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+publicationDate,title,abstract,id
+2021-12-15,Effect of magnetocrystalline anisotropy on magnetocaloric properties of AlFe$_{2}$B$_{2}$ compound,"It is well known that the temperature dependence of the effective
+magnetocrystalline anisotropy energy obeys the $l(l+1)/2$ power law of
+magnetization in the Callen-Callen theory. Therefore, according to the
+Callen-Callen theory, the magnetocrystalline anisotropy energy is assumed to be
+zero at the critical temperature where the magnetization is approximately zero.
+This study estimates the temperature dependence of the magnetocrystalline
+anisotropy energy by integrating the magnetization versus magnetic field
+($M$--$H$) curves, and found that the magnetocrystalline anisotropy is still
+finite even above the Curie temperature in the uniaxial anisotropy, whereas
+this does not appear in the cubic anisotropy case. The origin is the fast
+reduction of the anisotropy field, which is the magnetic field required to
+saturate the magnetization along the hard axis, in the case of cubic
+anisotropy. Therefore, the magnetization anisotropy and anisotropic magnetic
+susceptibility, those are the key factors of magnetic anisotropy, could not be
+established in the case of cubic anisotropy. In addition, the effect of
+magnetocrystalline anisotropy on magnetocaloric properties, as the difference
+between the entropy change curves of AlFe$_{2}$B$_{2}$ appears above the Curie
+temperature, which is in good agreement with a previous experimental study.
+This is proof of magnetic anisotropy at slightly above Curie temperature.",2112.08154v1
+2013-07-23,Mechanism of uniaxial magnetocrystalline anisotropy in transition metal alloys,"Magnetocrystalline anisotropy in transition metal alloys (FePt, CoPt, FePd,
+MnAl, MnGa, and FeCo) was studied using first-principles calculations to
+elucidate its specific mechanism. The tight-binding linear muffin-tin orbital
+method in the local spin-density approximation was employed to calculate the
+electronic structure of each compound, and the anisotropy energy was evaluated
+using the magnetic force theorem and the second-order perturbation theory in
+terms of spin-orbit interactions. We systematically describe the mechanism of
+uniaxial magnetocrystalline anisotropy in real materials and present the
+conditions under which the anisotropy energy can be increased. The large
+magnetocrystalline anisotropy energy in FePt and CoPt arises from the strong
+spin-orbit interaction of Pt. In contrast, even though the spin-orbit
+interaction in MnAl, MnGa, and FeCo is weak, the anisotropy energies of these
+compounds are comparable to that of FePd. We found that MnAl, MnGa, and FeCo
+have an electronic structure that is efficient in inducing the
+magnetocrystalline anisotropy in terms of the selection rule of spin-orbit
+interaction.",1307.5961v2
+2016-03-16,Illustrative view on the magnetocrystalline anisotropy of adatoms and monolayers,"Even though it has been known for decades that the magnetocrystalline
+anisotropy is linked to the spin-orbit coupling (SOC), the mechanism how it
+arises for specific systems is still subject of debate. We focused on finding
+markers of SOC in the density of states (DOS) and on employing them for
+understanding the source of magnetocrystalline anisotropy for the case of
+adatoms and monolayers. Fully relativistic ab-initio KKR-Green function
+calculations were performed for Fe, Co, and Ni adatoms and monolayers on
+Au(111) to investigate changes in the orbital-resolved DOS due to a rotation of
+magnetization. In this way one can see that a significant contribution to the
+magnetocrystalline anisotropy for adatoms comes from pushing of the SOC-split
+states above or below the Fermi level. As a result of this, the
+magnetocrystalline anisotropy energy crucially depends on the position of the
+energy bands of the adatom with respect to the Fermi level of the substrate.
+This view is supported by model crystal field Hamiltonian calculations.",1603.05053v2
+2018-09-29,Micromagnetic Simulations Study of Skyrmions in Magnetic FePt Nanoelements,"The magnetization reversal in 330 nm triangular prismatic magnetic
+nanoelements with variable magnetocrystalline anisotropy similar to that of
+partially chemically ordered FePt is studied using micromagnetic simulations
+employing Finite Element discretizations. Several magnetic properties including
+the evaluation of the magnetic skyrmion number $S$ are computed in order to
+characterize magnetic configurations exhibiting vortex-like formations.
+Magnetic vortices and skyrmions are revealed in different systems generated by
+the variation of the magnitude and relative orientation of the
+magnetocrystalline anisotropy direction, with respect to the normal to the
+triangular prism base. Micromagnetic configurations with skyrmion number
+greater than one have been detected for the case where magnetocrystalline
+anisotropy was normal to nanoelement's base. For particular magnetocrystalline
+anisotropy values three distinct skyrmions are formed and persist for a range
+of external fields. The simulation-based calculations of the skyrmion number S
+revealed that skyrmions can be created for magnetic nanoparticle systems
+lacking of chiral interactions such as Dzyaloshinsky-Moriya, but by only
+varying the magnetocrystalline anisotropy.",1810.00253v1
+2024-02-26,Efficient calculation of magnetocrystalline anisotropy energy using symmetry-adapted Wannier functions,"Magnetocrystalline anisotropy, a crucial factor in magnetic properties and
+applications like magnetoresistive random-access memory, often requires
+extensive $k$-point mesh in first-principles calculations. In this study, we
+develop a Wannier orbital tight-binding model incorporating crystal and spin
+symmetries and utilize time-reversal symmetry to divide magnetization
+components. This model enables efficient computation of magnetocrystalline
+anisotropy. Applying this method to $\mathrm{L1_0}$ $\mathrm{FePt}$ and
+$\mathrm{FeNi}$, we calculate the dependence of the anisotropic energy on
+$k$-point mesh size, chemical potential, spin-orbit interaction, and
+magnetization direction. The results validate the practicality of the models to
+the energy order of $10~[\mathrm{\mu eV}/f.u.]$.",2402.16331v1
+2017-08-04,Tunable dimensional crossover and magnetocrystalline anisotropy in Fe$_2$P-based alloys,"Electronic structure calculations are used to examine the magnetic properties
+of Fe$_2$P-based alloys and the mechanisms through which the Curie temperature
+and magnetocrystalline anisotropy can be optimized for specific applications.
+It is found that at elevated temperatures the magnetic interaction in pure
+Fe$_2$P develops a pronounced two-dimensional character due to the suppression
+of the magnetization in one of the sublattices, but the interlayer coupling is
+very sensitive to band filling and structural distortions. This feature
+suggests a natural explanation of the observed sharp enhancement of the Curie
+temperature by alloying with multiple elements, such as Co, Ni, Si, and B. The
+magnetocrystalline anisotropy is also tunable by electron doping, reaching a
+maximum near the electron count of pure Fe$_2$P. These findings enable the
+optimization of the alloy content, suggesting co-alloying of Fe$_2$P with Co
+(or Ni) and Si as a strategy for maximizing the magnetocrystalline anisotropy
+at and above room temperature.",1708.01683v2
+2020-06-07,Magnetocrystalline anisotropy of the easy-plane metallic antiferromagnet Fe$_2$As,"Magnetocrystalline anisotropy is a fundamental property of magnetic materials
+that determines the dynamics of magnetic precession, the frequency of spin
+waves, the thermal stability of magnetic domains, and the efficiency of
+spintronic devices. We combine torque magnetometry and density functional
+theory calculations to determine the magnetocrystalline anisotropy of the
+metallic antiferromagnet Fe$_2$As. Fe$_2$As has a tetragonal crystal structure
+with the N\'eel vector lying in the (001) plane. We report that the four-fold
+magnetocrystalline anisotropy in the (001)-plane of Fe$_2$As is extremely
+small, ${K_{22}} = - 150~{\rm{ J/}}{{\rm{m}}^{\rm{3}}}$ at T = 4 K, much
+smaller than perpendicular magnetic anisotropy of ferromagnetic structure
+widely used in spintronics device. ${K_{22}}$ is strongly temperature dependent
+and close to zero at T > 150 K. The anisotropy ${K_1}$ in the (010) plane is
+too large to be measured by torque magnetometry and we determine ${K_1} =
+-830~{\rm{ kJ/}}{{\rm{m}}^{\rm{3}}}$ using first-principles density functional
+theory. Our simulations show that the contribution to the anisotropy from
+classical magnetic dipole-dipole interactions is comparable to the contribution
+from spin-orbit coupling. The calculated four-fold anisotropy in the (001)
+plane ${K_{22}}$ ranges from $- 292~{\rm{ J/}}{{\rm{m}}^{\rm{3}}}$ to
+$280~{\rm{ J/}}{{\rm{m}}^{\rm{3}}}$, the same order of magnitude as the
+measured value. We use ${K_1}$ from theory to predict the frequency and
+polarization of the lowest frequency antiferromagnetic resonance mode and find
+that the mode is linearly polarized in the (001)-plane with $f = $ 670 GHz.",2006.04192v1
+1995-02-27,Magnetocrystalline Anisotropy Energy of a Transition Metal Monolayer: A Non-perturbative Theory,"The magnetocrystalline anisotropy energy $E_{anis}$ for a monolayer of Fe and
+Ni is determined using a fully convergent tight-binding calculation including
+$s$-$d$ hybridization. The spin-orbit interaction $\lambda_{so}$ is treated
+non-perturbatively. Remarkably, we find $E_{anis}\propto\lambda_{so}^2$ and
+important contributions to $E_{anis}$ due to the lifting of degeneracies near
+the Fermi-level. This is supported by the calculated decrease of the anisotropy
+energy with increasing temperature on a scale of several hundred K. Our results
+clarify the present debate on the origin of $E_{anis}$.",9502112v1
+2013-11-01,Strain-Tunable Magnetocrystalline Anisotropy in Epitaxial Y3Fe5O12 Thin Films,"We demonstrate strain-tuning of magnetocrystalline anisotropy over a range of
+more than one thousand Gauss in epitaxial Y3Fe5O12 films of excellent
+crystalline quality grown on lattice-mismatched Y3Al5O12 substrates.
+Ferromagnetic resonance (FMR) measurements reveal a linear dependence of both
+out-of-plane and in-plane uniaxial anisotropy on the strain-induced tetragonal
+distortion of Y3Fe5O12. Importantly, we find the spin mixing conductance G_r
+determined from inverse spin Hall effect and FMR linewidth broadening remains
+large: G_r = 3.33 x 10^14 Ohm^-1m^-2 in Pt/Y3Fe5O12/Y3Al5O12 heterostructures,
+quite comparable to the value found in Pt/Y3Fe5O12 grown on lattice-matched
+Gd3Ga5O12 substrates.",1311.0238v1
+2016-02-05,Skyrmions in thin films with easy-plane magnetocrystalline anisotropy,"We demonstrate that chiral skyrmionic magnetization configurations can be
+found as the minimum energy state in B20 thin film materials with easy-plane
+magnetocrystalline anisotropy with an applied magnetic field perpendicular to
+the film plane. Our observations contradict results from prior analytical work,
+but are compatible with recent experimental investigations. The size of the
+observed skyrmions increases with the easy-plane magnetocrystalline anisotropy.
+We use a full micromagnetic model including demagnetization and a
+three-dimensional geometry to find local energy minimum (metastable)
+magnetization configurations using numerical damped time integration. We
+explore the phase space of the system and start simulations from a variety of
+initial magnetization configurations to present a systematic overview of
+anisotropy and magnetic field parameters for which skyrmions are metastable and
+global energy minimum (stable) states.",1602.02064v2
+2003-10-10,Magnetocrystalline anisotropy and orbital polarization in ferromagnetic transition metals,"The magnetocrystalline anisotropy energies (MAEs) of the ferromagnetic metals
+bcc Fe, fcc and hcp Co, and fcc Ni have been calculated by using the {\it ab
+initio} tight-binding method. Disentangling the strong correlation among the
+$d$ orbitals with the Hamiltonian in the local spin-density approximation, we
+have investigated the orbital polarizations induced by the Hubbard $U$ and
+Racah $B$. The experimental MAE of fcc Ni is found with the value of $U$ close
+to that determined from experiments and used in other theories. With the
+optimized values of $U$ and $J$, both the MAEs and the orbital moments for Fe
+and Co are in close agreement with experiment.",0310249v1
+2005-08-31,Uniaxial magnetocrystalline anisotropy in ${\rm CaRuO_3}$,"${\rm CaRuO_3}$ is a paramagnetic metal and since its low temperature
+resistivity is described by $\rho=\rho_0+AT^\gamma $ with $\gamma \sim 1.5$, it
+is also considered a non-Fermi liquid (NFL) metal. We have performed extensive
+magnetoresistance and Hall effect measurements of untwinned epitaxial films of
+${\rm CaRuO_3}$. These measurements reveal that ${\rm CaRuO_3}$ exhibits
+uniaxial magnetocrystalline anisotropy. In addition, the low-temperature NFL
+behavior is most effectively suppressed when a magnetic field is applied along
+the easy axis, suggesting that critical spin fluctuations, possibly due to
+proximity of a quantum critical phase transition, are related to the NFL
+behavior.",0508038v1
+2011-09-30,An ultrafast image recovery and recognition system implemented with nanomagnets possessing biaxial magnetocrystalline anisotropy,"A circular magnetic disk with biaxial magnetocrystalline anisotropy has four
+stable magnetization states which can be used to encode a pixel's shade in a
+black/gray/white image. By solving the Landau-Lifshitz- Gilbert equation, we
+show that if moderate noise deflects the magnetization slightly from a stable
+state, it always returns to the original state, thereby automatically
+de-noising the corrupted image. The same system can compare a noisy input image
+with a stored image and make a matching decision using magneto-tunneling
+junctions. These tasks are executed at ultrahigh speeds (~2 ns for a
+512\times512 pixel image).",1109.6932v1
+2012-10-16,Degree of order dependence on magnetocrystalline anisotropy in bct FeCo alloys,"We investigate the magnetocrystalline anisotropy (MCA) energy of tetragonal
+distorted FeCo alloys depending on the degree of order by first-principles
+electronic structure calculation combined with the coherent potential
+approximation. The obtained results indicate that the MCA energy of FeCo alloys
+strongly depends on the degree of order under optimal conditions, where the
+axial ratio of the bct structure is 1.25 and the composition is Fe0.5Co0.5. We
+find that the modification of the electronic structure resulting from electron
+scattering by chemical disorder has a considerable influence on the MCA under
+these conditions.",1210.4386v1
+2016-02-26,Tuning the magnetocrystalline anisotropy in $R$CoPO by means of $R$ substitution: a ferromagnetic resonance study,"We report on broad-band electron spin resonance measurements performed within
+the itinerant ferromagnetic phase of $R$CoPO ($R$ = La, Pr, Nd and Sm). We
+reveal that the $R$ substitution is highly effective in gradually introducing a
+sizeable easy-plane magnetocrystalline anisotropy within the Co sublattice. We
+explain our results in terms of a subtle interplay of structural effects and of
+indirect interactions between the $f$ and $d$ orbitals from $R$ and Co,
+respectively.",1602.08377v1
+2016-12-27,Giant atomic magnetocrystalline anisotropy from degenerate orbitals around Fermi level,"Nano-structures with giant magnetocrystalline anisotropy energies (MAE) are
+desired in designing miniaturized magnetic storage and quantum computing
+devices. Through ab initio and model calculations, we propose that special
+p-element dimers and single-adatom on symmetry-matched substrates possess giant
+atomic MAE of 72-200 meV with room temperature structural stability. The huge
+MAE originates from degenerate orbitals around Fermi level. More importantly,
+we developed a simplified quantum mechanical model to understand the principle
+on how to obtain giant MAE for supported magnetic structures. These discoveries
+and mechanisms provide a paradigm to design giant atomic MAE in nanostructures.",1612.08679v1
+2022-01-27,Temperature Dependence of Magnetocrystalline Anisotropy in Itinerant Ferromagnets,"We theoretically investigated magnetocrystalline anisotropy (MA) at a finite
+temperature $T$ in ferromagnetic metals. Assuming a Rashba-type ferromagnet
+with uniaxial MA, we defined the MA constants $K_\mathrm{u}(T)$ derived from
+several different concepts. Our purpose was to examine the equality between
+them and to confirm a power law between $K_\mathrm{u}(T)$ and magnetization
+$M(T)$ in the form of $K_\mathrm{u}(T)/K_\mathrm{u}(0)=[M(T)/M(0)]^\alpha$. We
+demonstrate that $\alpha$ equals 2 in the itinerant-electron limit and
+increases with the localized feature of electrons passing through $\alpha=3$,
+predicted for the single-ion MA in spin models.",2201.11269v1
+2000-01-19,Fermi surface origin of the interrelationship between magnetocrystalline anisotropy and compositional order in transitional metal alloys,"Recently, we outlined a scheme to investigate the effects of compositional
+order on the magnetocrystalline anisotropy of alloys from a first-principles
+electronic structure point of view \{Phys. Rev. Lett. {\bf 83}, 5369 (1999)\}
+and showed that compositional order enhances the magnitude of
+magnetocrystalline anisotropy energy (MAE) of Co$_{0.5}$Pt$_{0.5}$ alloy by
+some two orders of magnitude as well as affecting the equilibrium magnetization
+direction. Here we describe our scheme in detail and present an in-depth study
+of the effect by demonstrating its Fermi surface origin. In
+Co$_{0.25}$Pt$_{0.75}$ alloy we find that the perfect $ L1_2 $ structure has a
+very small MAE whereas imposition of directional order enhances the MAE by two
+orders of magnitude. We also present the effect of lattice distortion
+(tetragonalization) on the MAE on the same footing and find that in the
+Co$_{0.5}$Pt$_{0.5}$ alloy it accounts for only about 20% of the observed MAE,
+thus confirming that compositional order is the major player in the enhancement
+of MAE. We also examine the directional chemical order that can be produced by
+magnetic annealing within the same framework. We extract a Fermi surface
+mechanism for the effect in an explicit study of permalloy. Finally, we propose
+that the Fermi surface plays a major role in the strong coupling between
+magnetocrystalline anisotropy and compositional order in many magnetic alloys.",0001271v1
+2005-04-20,Aligning spins in antiferromagnetic films using antiferromagnets,"We have explored the possibility to orient spins in antiferromagnetic thin
+films with low magnetocrystalline anisotropy via the exchange coupling to
+adjacent antiferromagnetic films with high magnetocrystalline anisotropy. We
+have used MnO as a prototype for a system with negligible single-ion
+anisotropy. We were able to control its spin direction very effectively by
+growing it as a film on antiferromagnetic CoO films with different
+predetermined spin orientations. This result may pave the way for tailoring
+antiferromagnets with low magnetocrystalline anistropy for applications in
+exchange bias systems. Very detailed information concerning the exchange
+coupling and strain effects was obtained from the Mn $L_{2,3}$ soft x-ray
+absorption spectroscopy.",0504520v2
+2010-03-30,Electric Field Effect on Magnetization and Magnetocrystalline Anisotropy at the Fe/MgO(001) Interface,"Density-functional calculations are performed to explore magnetoelectric
+effects originating from the influence of an external electric field on
+magnetic properties of the Fe/MgO(001) interface. It is shown that the effect
+on the interface magnetization and magnetocrystalline anisotropy can be
+substantially enhanced if the electric field is applied across a dielectric
+material with a large dielectric constant. In particular, we predict an
+enhancement of the interface magnetoelectric susceptibility by a factor of the
+dielectric constant of MgO over that of the free standing Fe (001) surface. We
+also predict a significant effect of electric field on the interface
+magnetocrystalline anisotropy due to the change in the relative occupancy of
+the 3d-orbitals of Fe atoms at the Fe/MgO interface. These results may be
+interesting for technological applications such as electrically controlled
+magnetic data storage.",1003.5870v1
+2014-09-17,Increased magnetocrystalline anisotropy in epitaxial Fe-Co-C thin films with spontaneous strain,"Rare earth free alloys are in focus of permanent magnet research since the
+accessibility of the elements needed for nowadays conventional magnets is
+limited. Tetragonally strained iron-cobalt (Fe-Co) has attracted large interest
+as promising candidate due to theoretical calculations. In experiments,
+however, the applied strain quickly relaxes with increasing film thickness and
+hampers stabilization of a strong magnetocrystalline anisotropy. In our study
+we show that already 2 at% of carbon substantially reduce the lattice
+relaxation leading to the formation of a spontaneously strained phase with 3 %
+tetragonal distortion. In these strained
+(Fe$_{0.4}$Co$_{0.6}$)$_{0.98}$C$_{0.02}$ films, a magnetocrystalline
+anisotropy above 0.4 MJ/m$^3$ is observed while the large polarization of 2.1 T
+is maintained. Compared to binary Fe-Co this is a remarkable improvement of the
+intrinsic magnetic properties. In this paper, we relate our experimental work
+to theoretical studies of strained Fe-Co-C and find a very good agreement.",1409.4952v1
+2017-06-12,Voltage-Controllable Colossal Magnetocrystalline Anisotropy in Single Layer Transition Metal Dichalcogenides,"Materials with large magnetocrystalline anisotropy and strong electric field
+effects are highly needed to develop new types of memory devices based on
+electric field control of spin orientations. Instead of using modified
+transition metal films, we propose that certain monolayer transition metal
+dichalcogenides are the ideal candidate materials for this purpose. Using
+density functional calculations, we show that they exhibit not only a large
+magnetocrystalline anisotropy (MCA), but also colossal voltage modulation under
+external field. Notably, in some materials like CrSe_2 and FeSe_2, where spins
+show a strong preference for in-plane orientation, they can be switched to
+out-of-plane direction. This effect is attributed to the large band character
+alteration that the transition metal d-states undergo around the Fermi energy
+due to the electric field. We further demonstrate that strain can also greatly
+change MCA, and can help to improve the modulation efficiency while combined
+with an electric field.",1706.03521v1
+2018-01-20,Magnetic Behaviour of Assemblies of Interacting Cobalt-Carbide Nanoparticles,"Recent work [1] demonstrated high coercivity and magnetic moment in cobalt
+carbide nanoparticle assemblies and explained the high coercivity from first
+principles in terms of the high magnetocrystalline anisotropy of the cobalt
+carbide nanoparticles. In this work, we comprehensively model the interaction
+between the nanoparticles comprising the assembly and systematically understand
+the effect of particle size, distribution of the orientations of the
+nanoparticles' magnetocrystalline anisotropy axis with respect to the applied
+magnetic field, and dipole coupling between nanoparticles on the temperature
+dependent magnetic behavior of the nanoparticle assembly. We show that
+magnetocrystalline anisotropy alone is not enough to explain the large
+hysteresis over the 50K-400K temperature range and suggest that defects and
+inhomogeneties that pin the magnetization could also play a significant role on
+this temperature dependent magnetic behavior.",1801.06672v1
+2018-02-22,Power law analysis for temperature dependence of magnetocrystalline anisotropy constants of Nd$_2$Fe$_{14}$B magnets,"Phenomenological analysis for the temperature dependence of the
+magnetocrystalline anisotropy (MA) in rare earth magnets is presented. We
+define phenomenological power laws applicable to compound magnets using the
+Zener theory, apply these laws to the magnetocrystalline anisotropy constants
+(MACs) of Nd$_2$Fe$_{14}$B magnets. The results indicate that the MACs obey the
+power law well, and a general understanding for the temperature-dependent MA in
+rare earth magnets is obtained through the analysis. Furthermore, to examine
+the validity of the power law, we discuss the temperature dependence of the
+MACs in Dy$_2$Fe$_{14}$B and Y$_2$Fe$_{14}$B magnets as examples wherein it is
+difficult to interpret the MA using the power law.",1802.07959v2
+2018-03-22,Large Perpendicular Magnetocrystalline Anisotropy at Fe/Pb(001) interface,"Search for ultrathin magnetic film with large perpendicular
+magnetocrystalline anisotropy (PMA) has been inspired for years by the
+continuous miniaturization of magnetic units in spintronics devices. The common
+magnetic materials used in research and applications are based on Fe because
+the pure Fe metal is the best yet simple magnetic material from nature. Through
+systematic first-principles calculations, we explored the possibility to
+produce large PMA with ultrathin Fe on non-noble and non-magnetic Pb(001)
+substrate. Interestingly, huge magnetocrystalline anisotropy energy (MAE) of
+7.6 meV was found in Pb/Fe/Pb(001) sandwich structure with only half monolayer
+Fe. Analysis of electronic structures reveals that the magnetic proximity
+effect at the interface is responsible for this significant enhancement of MAE.
+The MAE further increases to 13.6 meV with triply repeated capping Pb and
+intermediate Fe layers. Furthermore, the MAE can be tuned conveniently by
+charge injection.",1803.08219v1
+2020-09-01,Lattice dynamics effects on the magnetocrystalline anisotropy energy: application to MnBi,"Using a first-principles fully relativistic scheme based on ultrasoft
+pseudopotentials and density functional perturbation theory, we study the
+magnetocrystalline anisotropy free energy of the ferromagnetic binary compound
+MnBi. We find that differences in the phonon dispersions due to the different
+orientations of the magnetization (in-plane and perpendicular to the plane)
+give a difference between the vibrational free energies of the high-temperature
+and low-temperature phases. This vibrational contribution to the
+magnetocrystalline anisotropy energy (MAE) constant, $K_u$, is non-negligible.
+When the energy contribution to the MAE is calculated by the PBEsol exchange
+and correlation functional, the addition of the phonon contribution allows to
+get a $T = 0$ K $K_u$ and a spin-reorientation transition temperature in
+reasonable agreement with experiments.",2009.00410v1
+2014-04-22,First principles investigation of magnetocrystalline anisotropy at the L2$_1$ Full Heusler|MgO interfaces and tunnel junctions,"Magnetocrystalline anisotropy at Heusler alloy$|$MgO interfaces have been
+studied using first principles calculations. It is found that Co terminated
+Co$_{2}$FeAl$|$MgO interfaces show perpendicular magnetic anisotropy up to 1.31
+mJ/m$^2$, while those with FeAl termination exhibit in-plane magnetic
+anisotropy. Atomic layer resolved analysis indicates that the origin of
+perpendicular magnetic anisotropy in Co$_{2}$FeAl$|$MgO interfaces can be
+attributed to the out-of-plane orbital contributions of interfacial Co atoms.
+At the same time, Co$_{2}$MnGe and Co$_{2}$MnSi interfaced with MgO tend to
+favor in-plane magnetic anisotropy for all terminations.",1404.5646v2
+2018-05-29,Electronic structure and magnetic anisotropies of antiferromagnetic transition-metal difluorides,"We compare GGA+U calculations with available experimental data and analyze
+the origin of magnetic anisotropies in MnF$_2$, FeF$_2$, CoF$_2$, and NiF$_2$.
+We confirm that the magnetic anisotropy of MnF$_2$ stems almost completely from
+the dipolar interaction, while magnetocrystalline anisotropy energy plays a
+dominant role in the other three compounds, and discuss how it depends on the
+details of band structure. The latter is critically compared to available
+optical measurements. The case of CoF$_2$, where magnetocrystalline anisotropy
+energy strongly depends on $U$, is put into contrast with FeF$_2$ where
+theoretical predictions of magnetic anisotropies are nearly quantitative.",1805.11339v3
+2023-05-18,Giant coercivity induced by perpendicular anisotropy in Mn2.42Fe0.58Sn single crystals,"We report the discovery of a giant out-of-plane coercivity in the Fe-doped
+Mn3Sn single crystals. The compound of Mn2.42Fe0.58Sn exhibits a series of
+magnetic transitions accompanying with large magnetic anisotropy and electric
+transport properties. Compared with the ab-plane easy axis in Mn3Sn, it
+switches to the c-axis in Mn2.42Fe0.58Sn, producing a sufficiently large
+uniaxial anisotropy. At 2 K, a giant out-of-plane coercivity (Hc) up to 3 T was
+observed, which originates from the large uniaxial magnetocrystalline
+anisotropy. The modified Sucksmith-Thompson method was used to determine the
+values of the second-order and the fourth-order magnetocrystalline anisotropy
+constants K1 and K2, resulting in values of 6.0 * 104 J/m3 and 4.1 * 105 J/m3
+at 2 K, respectively. Even though the Curie temperature (TC) of 200 K for
+Mn2.42Fe0.58Sn is not high enough for direct application, our research presents
+a valuable case study of a typical uniaxial anisotropy material.",2305.10876v2
+1996-09-03,Magnetocrystalline Anisotropy Energy of Transition Metal Thin Films: A Non-perturbative Theory,"The magnetocrystalline anisotropy energy E(anis) of free-standing monolayers
+and thin films of Fe and Ni is determined using two different semi-empirical
+schemes. Within a tight-binding calculation for the 3d bands alone, we analyze
+in detail the relation between bandstructure and E(anis), treating spin-orbit
+coupling non-pertubatively. We find important contributions to E(anis) due to
+the lifting of band degeneracies near the Fermi level by SOC. The important
+role of degeneracies is supported by the calculation of the electron
+temperature dependence of the magnetocrystalline anisotropy energy, which
+decreases with the temperature increasing on a scale of several hundred K. In
+general, E(anis) scales with the square of the SOC constant. Including 4s bands
+and s-d hybridization, the combined interpolation scheme yields anisotropy
+energies that quantitatively agree well with experiments for Fe and Ni
+monolayers on Cu(001). Finally, the anisotropy energy is calculated for systems
+of up to 14 layers. Even after including s-bands and for multilayers, the
+importance of degeneracies persists. Considering a fixed fct-Fe structure, we
+find a reorientation of the magnetization from perpendicular to in-plane at
+about 4 layers. For Ni, we find the correct in-plane easy-axis for the
+monolayer. However, since the anisotropy energy remains nearly constant, we do
+not find the experimentally observed reorientation.",9609028v1
+2020-07-02,Interfacial giant tunnel magnetoresistance and bulk-induced large perpendicular magnetic anisotropy in (111)-oriented junctions with fcc ferromagnetic alloys: A first-principles study,"We study the tunnel magnetoresistance (TMR) effect and magnetocrystalline
+anisotropy in a series of magnetic tunnel junctions (MTJs) with $L1_1$-ordered
+fcc ferromagnetic alloys and MgO barrier along the [111] direction. Considering
+the (111)-oriented MTJs with different $L1_1$ alloys, we calculate their TMR
+ratios and magnetocrystalline anisotropies on the basis of the first-principles
+calculations. The analysis shows that the MTJs with Co-based alloys (CoNi,
+CoPt, and CoPd) have high TMR ratios over 2000$\%$. These MTJs have
+energetically favored Co-O interfaces where interfacial antibonding between Co
+$d$ and O $p$ states is formed around the Fermi level. We find that the
+resonant tunneling of the antibonding states, called the interface resonant
+tunneling, is the origin of the obtained high TMR ratios. Our calculation of
+the magnetocrystalline anisotropy shows that many $L1_1$ alloys have large
+perpendicular magnetic anisotropy (PMA). In particular, CoPt has the largest
+value of anisotropy energy $K_{\rm u} \approx 10\,{\rm MJ/m^3}$. We further
+conduct a perturbation analysis of the PMA with respect to the spin-orbit
+interaction and reveal that the large PMA in CoPt and CoNi mainly originates
+from spin-conserving perturbation processes around the Fermi level.",2007.01068v2
+2019-04-27,Critical Behavior and Anisotropy in Single Crystal SrRuO$_3$,"The magnetization of single crystal SrRuO3 is studied as a function of
+temperature along different crystallographic directions. The magnetocrystalline
+anisotropy and behavior near the critical transition temperature are analyzed
+in detail. The magnetization vs temperature is found to vary more like $T^2$
+rather than $T^{3/2}$ expected for spin waves.",1904.12193v1
+2019-06-21,Strain and thickness effects on magnetocrystalline anisotropy of CoFe(011) films,"We investigate MCA of CoFe(011) thin films as a function of strength of
+strain and film thickness has been studied. It is elucidated that perpendicular
+magnetocystalline anisotropy (MCA) energy (EMCA) is getting stronger with
+compressed xy-plane lattice constant while in-plane MCA is become an easy-axis
+by tensile strain on xy-plane. The reason of the EMCA behaviors can be
+explained by features of electronic structures.",1906.09153v1
+2009-11-15,Field induced resistivity anisotropy in SrRuO3 films,"SrRuO3 is an itinerant ferromagnet with orthorhombic structure and uniaxial
+magnetocrystalline anisotropy - features expected to yield resistivity
+anisotropy. Here we explore changes in the resistivity anisotropy of epitaxial
+SrRuO3 films due to induced magnetization in the paramagnetic state by using
+the planar Hall effect. We find that the effect of the induced magnetization on
+the in-plane anisotropy is strongly angular dependent, and we provide a full
+description of this behavior at 160 K for induced magnetization in the (001)
+plane.",0911.2879v1
+2019-01-14,First-principles calculations of the magnetocrystalline anisotropy of the prototype 2:17 cell boundary phase Y(Co$_{1-x-y}$Fe$_x$Cu$_y$)$_5$,"We present a computational study of the compound
+Y(Co$_{1-x-y}$Fe$_x$Cu$_y$)$_5$ for 0 $\leq x,y \leq 0.2$. This compound was
+chosen as a prototype for investigating the cell boundary phase believed to
+play a key role in establishing the high coercivity of commercial Sm-Co 2:17
+magnets. Using density-functional theory, we have calculated the magnetization
+and magnetocrystalline anisotropy at zero temperature for a range of
+compositions, modeling the doped compounds within the coherent potential
+approximation. We have also performed finite temperature calculations for
+YCo$_5$, Y(Co$_{0.838}$Cu$_{0.162}$)$_5$ and
+Y(Co$_{0.838}$Fe$_{0.081}$Cu$_{0.081}$)$_5$ within the disordered local moment
+picture. Our calculations find that substituting Co with small amounts of
+either Fe or Cu boosts the magnetocrystalline anisotropy $K$, but the change in
+$K$ depends strongly on the location of the dopants. Furthermore, the
+calculations do not show a particularly large difference between the magnetic
+properties of Cu-rich Y(Co$_{0.838}$Cu$_{0.162}$)$_5$ and equal Fe-Cu
+Y(Co$_{0.838}$Fe$_{0.081}$Cu$_{0.081}$)$_5$, despite these two compositions
+showing different coercivity behavior when found in the cell boundary phase of
+2:17 magnets. Our study lays the groundwork for studying the rare earth
+contribution to the anisotropy of Sm(Co$_{1-x-y}$Fe$_x$Cu$_y$)$_5$, and also
+shows how a small amount of transition metal substitution can boost the
+anisotropy field of YCo$_5$.",1901.04185v1
+2010-07-16,"Strain control of magnetic anisotropy in (Ga,Mn)As microbars","We present an experimental and theoretical study of magnetocrystalline
+anisotropies in arrays of bars patterned lithographically into (Ga,Mn)As
+epilayers grown under compressive lattice strain. Structural properties of the
+(Ga,Mn)As microbars are investigated by high-resolution X-ray diffraction
+measurements. The experimental data, showing strong strain relaxation effects,
+are in good agreement with finite element simulations. SQUID magnetization
+measurements are performed to study the control of magnetic anisotropy in
+(Ga,Mn)As by the lithographically induced strain relaxation of the microbars.
+Microscopic theoretical modeling of the anisotropy is performed based on the
+mean-field kinetic-exchange model of the ferromagnetic spin-orbit coupled band
+structure of (Ga,Mn)As. Based on the overall agreement between experimental
+data and theoretical modeling we conclude that the micropatterning induced
+anisotropies are of the magnetocrystalline, spin-orbit coupling origin.",1007.2766v1
+2022-04-29,"Controlled Curie temperature, magnetocrystalline anisotropy, and valley polarization in 2D ferromagnetic Janus 2H-VSeS monolayer","Inspired by the successful synthesis of two-dimensional (2D) V-based Janus
+dichloride monolayers with intrinsic ferromagnetism and high Curie temperature
+(T$_{c}$), the electronic structure, spin-valley splitting and magnetic
+anisotropy of Janus 2H-VSeS monolayers are investigated in detailed using
+first-principles calculations. The results show that the Janus 2H-VSeS
+monolayer exhibits a large valley splitting of 105meV, high T$_{c}$ of 278K and
+good magnetocrystalline anisotropy (0.31meV) contributed by the in-plane
+d$_{x^{2}-y^{2}}$/d$_{xy}$ orbitals of V atoms. The biaxial strain
+($-$8%<$\varepsilon$<8%) can effectively tune the magnetic moments of V atom,
+valley splitting $\Delta$E, T$_{c}$ and MAE of Janus 2H-VSeS monolayer. The
+corresponding $\Delta$E and T$_{c}$ are adjusted from 72meV to 106.8meV and
+from 180K to 340K, respectively. The electronic phase transition from bipolar
+magnetic semiconductor (BMS) to half-semiconductor (HSC), spin gapless
+semiconductor (SGS), and half-metal (HM) is also observed due to the change of
+V 3d-orbital occupation. Due to the broken space- and time-reversal symmetry,
+the opposite valley charge carriers carry opposite Berry curvature, which leads
+to prominent anomalous Hall conductivity at the K and K$^{\prime}$ valleys. The
+maximum modulation of Berry curvature can reach to 45% and 9.5% by applying the
+biaxial strain and charge carrier doping, respectively. The stable in-plane
+magnetocrystalline anisotropy and large spontaneous valley polarization make
+the ferromagnetic Janus 2H-VSeS monolayer a promising material for achieving
+the spintronics and valleytronics devices.",2205.00106v2
+2011-08-30,"Spin-orbit coupling effect in (Ga,Mn)As films: anisotropic exchange interactions and magnetocrystalline anisotropy","The magneto-crystalline anisotropy (MCA) of (Ga,Mn)As films has been studied
+on the basis of ab-initio electronic structure theory by performing magnetic
+torque calculations. An appreciable contribution to the in-plane uniaxial
+anisotropy can be attributed to an extended region adjacent to the surface.
+Calculations of the exchange tensor allow to ascribe a significant part to the
+MCA to the exchange anisotropy, caused either by a tetragonal distortion of the
+lattice or by the presence of the surface or interface.",1108.5870v1
+2012-02-14,Magnetic anisotropies of quantum dots,"Magnetic anisotropies in quantum dots (QDs) doped with magnetic ions are
+discussed in terms of two frameworks: anisotropic $g$-factors and
+magnetocrystalline anisotropy energy. It is shown that even a simple model of
+zinc-blende p-doped QDs displays a rich diagram of magnetic anisotropies in the
+QD parameter space. Tuning the confinement allows to control magnetic easy axes
+in QDs in ways not available for the better-studied bulk.",1202.3145v1
+2001-06-03,Magnetization reversal by uniform rotation (Stoner-Wohlfarth model) in f.c.c. cobalt nanoparticles,"The combination of high sensitive superconducting quantum interference device
+(SQUID) with high quality nanoparticles allowed to check the simplest classical
+model describing the magnetisation reversal by uniform rotation which were
+proposed more than 50 years ago by Neel, Stoner and Wohlfarth. The micrometer
+sized SQUIDs were elaborated by electron beam lithography and the nanoparticles
+were synthesised by arc-discharge. The measured angular dependence of switching
+fields of nearly all f.c.c. Co nanoparticles revealed a dominating uniaxial
+magnetic anisotropy. This result suggests that twin boundaries and stacking
+faults strongly alter the cubic magnetocrystalline anisotropy leading to
+dominating uniaxial anisotropy. However, few particles were sufficiently
+""perfect"" in order to show a more complex switching field surface and a field
+path dependence of the switching field which is the important signature of the
+cubic magnetocrystalline anisotropy.",0106035v1
+2007-07-23,"Magnetocrystalline anisotropy controlled local magnetic configurations in (Ga,Mn)As spin-transfer-torque microdevices","The large saturation magnetization in conventional dense moment ferromagnets
+offers flexible means of manipulating the ordered state through demagnetizing
+shape anisotropy fields but these dipolar fields, in turn, limit the
+integrability of magnetic elements in information storage devices. We show that
+in a (Ga,Mn)As dilute moment ferromagnet, with comparatively weaker magnetic
+dipole interactions, locally tunable magnetocrystalline anisotropy can take the
+role of the internal field which determines the magnetic configuration.
+Experiments and theoretical modeling are presented for lithographically
+patterned microchannels and the phenomenon is attributed to lattice relaxations
+across the channels. The utility of locally controlled magnetic anisotropies is
+demonstrated in current induced switching experiments. We report structure
+sensitive, current induced in-plane magnetization switchings well below the
+Curie temperature at critical current densities 10^5 Acm^-2. The observed
+phenomenology shows signatures of a contribution from domain-wall
+spin-transfer-torque effects.",0707.3329v1
+2011-03-19,Magnetic dynamics of single domain Ni nanoparticles,"The dynamic magnetic properties of Ni nanoparticles diluted in an amorphous
+SiO2 matrix prepared from a modified sol-gel method have been studied by the
+frequency f dependence of the ac magnetic susceptibility \c{hi}(T). For samples
+with similar average radii ~ 3-4 nm, an increase of the blocking temperature
+from TB ~ 20 to ~ 40 K was observed for Ni concentrations of ~ 1.5 and 5 wt.%,
+respectively, assigned to the effects of dipolar interactions. Both the
+in-phase \c{hi}'(T) and the out-of-phase \c{hi}""(T) maxima follow the
+predictions of the thermally activated N\'eel-Arrhenius model. The effective
+magnetic anisotropy constant Keff inferred from \c{hi}""(T) versus f data for
+the 1.5 wt.% Ni sample is close to the value of the magnetocrystalline
+anisotropy of bulk Ni, suggesting that surface effects are negligible in the
+present samples. In addition, the contribution from dipolar interactions to the
+total anisotropy energy Ea in specimens with 5 wt.% Ni was found to be
+comparable to the intrinsic magnetocrystalline anisotropy barrier.",1103.3783v1
+2013-09-18,"Magnetocrystalline anisotropy energy of Fe$(001)$, Fe$(110)$ slabs and nanoclusters: a detailed local analysis within a tight-binding model","We report tight-binding (TB) calculations of magnetocrystalline anisotropy
+energy (MAE) of Iron slabs and nanoclusters with a particuler focus on local
+analysis. After clarifying various concepts and formulations for the
+determination of MAE, we apply our realistic TB model to the analysis of the
+magnetic anisotropy of Fe$(001)$, Fe$(110)$ slabs and of two large Fe clusters
+with $(001)$ and $(110)$ facets only: a truncated pyramid and a truncated
+bipyramid containg 620 and 1096 atoms, respectively. It is shown that the MAE
+of slabs originates mainly from outer layers, a small contribution from the
+bulk gives rise, however, to an oscillatory behavior for large thicknesses.
+Interestingly, the MAE of the nanoclusters considered is almost solely due to
+$(001)$ facets and the base perimeter of the pyramid. We believe that this fact
+could be used to efficiently control the anisotropy of Iron nanoparticles and
+could also have consequences on their spin dynamics.",1309.4578v1
+2018-03-01,Calculating the Magnetic Anisotropy of Rare-Earth-Transition-Metal Ferrimagnets,"Magnetocrystalline anisotropy, the microscopic origin of permanent magnetism,
+is often explained in terms of ferromagnets. However, the best performing
+permanent magnets based on rare earths and transition metals (RE-TM) are in
+fact ferrimagnets, consisting of a number of magnetic sublattices. Here we show
+how a naive calculation of the magnetocrystalline anisotropy of the classic
+RE-TM ferrimagnet GdCo$_5$ gives numbers which are too large at 0 K and exhibit
+the wrong temperature dependence. We solve this problem by introducing a
+first-principles approach to calculate temperature-dependent magnetization vs.
+field (FPMVB) curves, mirroring the experiments actually used to determine the
+anisotropy. We pair our calculations with measurements on a recently-grown
+single crystal of GdCo$_5$, and find excellent agreement. The FPMVB approach
+demonstrates a new level of sophistication in the use of first-principles
+calculations to understand RE-TM magnets.",1803.00235v1
+2019-04-09,Ferromagnetic Resonance Studies of Strain tuned Bi:YIG Films,"Bismuth-doped Yttrium iron garnet (Bi:YIG) thin films known for large
+Magneto-optical activity with low losses still needs to get probed for its
+magnetization dynamics. We demonstrate a controlled tuning of
+magnetocrystalline anisotropy in Bi-doped Y_3 Fe_5 O_12 (Bi:YIG) films of high
+crystalline quality using growth induced epitaxial strain on [111]-oriented
+Gd_3 Ga_5 O_12 (GGG) substrate. We optimize a growth protocol to get thick
+highly-strained epitaxial films showing large magneto-crystalline anisotropy,
+compare to thin films prepared using a different protocol. Ferromagnetic
+resonance measurements establish a linear dependence of the out-of-plane
+uniaxial anisotropy on the strain induced rhombohedral distortion of Bi:YIG
+lattice. Interestingly, the enhancement in the magnetoelastic constant due to
+an optimum substitution of Bi^(3+) ions with strong spin orbit coupling does
+not strongly affect the precessional damping (~2x10^(-3) ). Large
+magneto-optical activity, reasonably low damping, large magnetocrystalline
+anisotropy and large magnetoelastic coupling in BiYIG are the properties that
+may help BiYIG emerge as a possible material for photo-magnonics and other
+spintronics applications.",1904.04800v2
+2021-06-22,Quantum-confined charge transfer that enhances magnetic anisotropy in lanthanum M-type hexaferrites,"Iron-based hexaferrites are critical-element-free permanent magnet components
+of magnetic devices. Of particular interest is electron-doped M-type
+hexaferrite i.e., LaFe$_{12}$O$_{19}$ (LaM) in which extra electrons introduced
+by lanthanum substitution of barium/strontium play a key role in uplifting the
+magnetocrystalline anisotropy. We investigate the electronic structure of
+lanthanum hexaferrite using a \textit{localized} density functional theory
+which reproduces semiconducting behavior and identifies the origin of the very
+large magnetocrystalline anisotropy. Localized charge transfer from lanthanum
+to the iron at the crystal's $2a$ site produces a narrow $3d_{z^2}$ valence
+band strongly locking the magnetization along the $c$ axis. The calculated
+uniaxial magnetic anisotropy energies from fully self-consistent calculations
+are nearly double the single-shot values, and agree well with available
+experiments. The chemical similarity of lanthanum to other rare earths suggests
+that LaM can host for other rare earths possessing non-trivial $4f$ electronic
+states for, \textit{e.g.,} microwave-optical quantum transduction.",2106.11947v1
+2021-04-05,Transverse Rashba Effect and Unconventional Magnetocrystalline Anisotropy in Double-Gd-adsorbed Zigzag Graphene Nanoribbon,"The transverse Rashba effect is proposed and investigated by the
+first-principle calculations based on density functional theory in a
+quasi-one-dimensional antiferromagnet with a strong perpendicular
+magnetocrystalline anisotropy, which is materialized by the Gd-adsorbed
+graphene nanoribbon with a centric symmetry. The Rashba effect in this system
+is associated with the local dipole field transverse to and in the plane of the
+nanoribbon. That dipole field is induced by the off-center adsorption of the Gd
+adatom above the hex-carbon ring near the nanoribbon edges. The transverse
+Rashba effect at the two Gd adatoms enhances each other in the
+antiferromagnetic (AFM) ground state and cancels each other in the
+ferromagnetic (FM) meta-stable state, because of the centrosymmetric atomic
+structure. The transverse Rashba parameter is 1.51 eV A. This system shows a
+strong perpendicular magnetocrystalline anisotropy (MCA), which is 1.4 meV per
+Gd atom in the AFM state or 2.2 meV per Gd atom in the FM state. The origin of
+the perpendicular MCA is analyzed in k-space by filtering out the contribution
+of the transverse Rashba effect from the band structures perturbed by the
+spin-orbit coupling interactions. The first-order perturbation of the orbit and
+spin angular momentum coupling is the major source of the MCA, which is
+associated with the one-dimensionality of the system. The transverse Rashba
+effect and the strong perpendicular magnetization hosted simultaneously by the
+proposed AFM Gd-adsorbed graphene nanoribbon lock the up- (or down-) spin
+quantization direction to the forward (or backward) movement. This finding
+offers a magnetic approach to a high coherency spin propagation in
+one-dimensionality, and open a new door to manipulating spin transportation in
+graphene-based spintronics.",2104.01922v1
+2022-04-11,DFT calculation of intrinsic properties of magnetically hard phase L1$\mathrm{_0}$ FePt,"Due to its strong magnetocrystalline anisotropy, FePt L1$\mathrm{_0}$ phase
+is considered as a promising magnetic recording media material. Although the
+magnetic properties of this phase have already been analyzed many times using
+density functional theory (DFT), we decided to study it again, emphasizing on
+full potential methods, including spin-polarized relativistic
+Korringa-Kohn-Rostoker (SPR-KKR) and full-potential local-orbital (FPLO)
+scheme. In addition to the determination of exact values of the
+magnetocrystalline anisotropy constants K$\mathrm{_1}$ and K$\mathrm{_2}$, the
+magnetic moments (m), the Curie temperature, and the magnetostriction
+coefficient, we focused on the investigation of the magnetocrystalline
+anisotropy energy (MAE) dependence on the magnetic moment values using the
+fully relativistic fixed spin moment (FSM) method with various
+exchange-correlation potentials. We present nearly identical MAE(m) curves near
+the equilibrium point, along with different equilibrium values of MAE and
+magnetic moments. For a magnetic moment reduced by about 10%, we determined a
+theoretical MAE maximum in the ground state (0 K) equal to about 20.3 MJ
+m$\mathrm{^{-3}}$ and independent of the choice of the exchange-correlation
+potential form. These calculations allow us to understand the discrepancies
+between the previous MAE results for different exchange-correlation potentials.",2204.05073v1
+2007-03-23,Magnetocrystalline anisotropy and magnetization reversal in GaMnP synthesized by ion implantation and pulsed-laser melting,"We report the observation of ferromagnetic resonance (FMR) and the
+determination of the magnetocrystalline anisotropy in (100)-oriented
+single-crystalline thin film samples of GaMnP with x=0.042. The contributions
+to the magnetic anisotropy were determined by measuring the angular- and the
+temperature-dependencies of the FMR resonance fields and by superconducting
+quantum interference device magnetometry. The largest contribution to the
+anisotropy is a uniaxial component perpendicular to the film plane; however, a
+negative contribution from cubic anisotropy is also found. Additional in-plane
+uniaxial components are observed at low temperatures, which lift the degeneracy
+between the in-plane [011] and [01-1] directions as well as between the
+in-plane [010] and [001] directions. Near T=5K, the easy magnetization axis is
+close to the in-plane [01-1] direction. All anisotropy parameters decrease with
+increasing temperature and disappear above the Curie temperature T_C. A
+consistent picture of the magnetic anisotropy of ferromagnetic GaMnP emerges
+from the FMR and magnetometry data. The latter can be successfully modeled when
+both coherent magnetization rotation and magnetic domain nucleation are
+considered.",0703625v1
+2011-06-09,Quantitative model for anisotropy and reorientation thickness of the magnetic moment in thin epitaxially strained metal films,"A quantitative mathematical model for the critical thickness of strained
+epitaxial metal films is presented, at which the magnetic moment experiences a
+reorientation from in-plane to perpendicular magnetic anisotropy. The model is
+based on the minimum of the magnetic anisotropy energy with respect to the
+orientation of the magnetic moment of the film. Magnetic anisotropy energies
+are taken as the sum of shape anisotropy, magnetocrystalline anisotropy and
+magnetoelastic anisotropy, the two latter ones being present as constant
+surface and variable volume contributions. Other than anisotropy materials
+constants, readily available from literature, only information about the strain
+in the films for the determination of the magnetoelastic anisotropy energy is
+required. Application of the epitaxial Bain path allows to express the strain
+in the film in terms of substrate lattice constant and film lattice parameter,
+and thus to obtain an approximate closed expression for the reorientation
+thickness in terms of lattice mismatch. The model can predict the critical spin
+reorientation transition thickness with surprising accuracy.",1106.1917v1
+2015-02-20,Magnetic properties of (Fe$_{1-x}$Co$_x$)$_2$B alloys and the effect of doping by 5$d$ elements,"We have explored, computationally and experimentally, the magnetic properties
+of \fecob{} alloys. Calculations provide a good agreement with experiment in
+terms of the saturation magnetization and the magnetocrystalline anisotropy
+energy with some difficulty in describing Co$_2$B, for which it is found that
+both full potential effects and electron correlations treated within dynamical
+mean field theory are of importance for a correct description. The material
+exhibits a uniaxial magnetic anisotropy for a range of cobalt concentrations
+between $x=0.1$ and $x=0.5$. A simple model for the temperature dependence of
+magnetic anisotropy suggests that the complicated non-monotonous temperature
+behaviour is mainly due to variations in the band structure as the exchange
+splitting is reduced by temperature. Using density functional theory based
+calculations we have explored the effect of substitutional doping the
+transition metal sublattice by the whole range of 5$d$ transition metals and
+found that doping by Re or W elements should significantly enhance the
+magnetocrystalline anisotropy energy. Experimentally, W doping did not succeed
+in enhancing the magnetic anisotropy due to formation of other phases. On the
+other hand, doping by Ir and Re was successful and resulted in magnetic
+anisotropies that are in agreement with theoretical predictions. In particular,
+doping by 2.5~at.\% of Re on the Fe/Co site shows a magnetocrystalline
+anisotropy energy which is increased by 50\% compared to its parent
+(Fe$_{0.7}$Co$_{0.3}$)$_2$B compound, making this system interesting, for
+example, in the context of permanent magnet replacement materials or in other
+areas where a large magnetic anisotropy is of importance.",1502.05916v3
+2000-05-02,Magnetoelastic coupling in epitaxial magnetic films: An ab-initio study,"A method is developed which allows to determine the first-order and the
+second-order magnetoelastic coefficients of a magnetic bulk material from the
+ab-initio calculation of the magnetocrystalline anisotropy energy as function
+of a prestrain. Excplicit results are given for bcc Fe, and they agree well
+with experimental data obtained from the magnetostrictive stress measurements
+for epitaxial Fe films.",0005053v1
+2002-10-31,Superradiant Operation of Spin Masers,"The theory of spin superradiance, developed earlier for nuclear magnets, is
+generalized to a wider class of spin systems, such as granular magnets and
+molecular magnets. The latter may possess strong single-site magnetocrystalline
+anisotropy, whose role in nonlinear spin dynamics is analysed. Transient as
+well as pulsing superradiant regimes are described. These coherent regimes may
+be employed in the operation of spin masers.",0210698v1
+2004-04-08,Stoner-Wohlfart model applied to bicrystal magnetoresistance hysteresis,"We calculate numerically the magnetization direction as function of magnetic
+field in the Stoner-Wohlfart theory and are able to reproduce the shape of the
+low-field magnetoresistance hysteresis observed in manganite grain boundary
+junctions. Moreover, we show that it is necessary to include biaxial
+magnetocrystalline anisotropy to fully describe the grain boundary
+magnetoresistance in La$_{0.7}$Sr$_{0.3}$MnO$_3$/SrTiO$_3$ bicrystal tunnel
+junctions.",0404193v1
+2014-02-22,LDA+DMFT Approach to Magnetocrystalline Anisotropy of Strong Magnets,"The new challenges posed by the need of finding strong rare-earth free
+magnets demand methods that can predict magnetization and magnetocrystalline
+anisotropy energy (MAE). We argue that correlated electron effects, which are
+normally underestimated in band structure calculations, play a crucial role in
+the development of the orbital component of the magnetic moments. Because
+magnetic anisotropy arises from this orbital component, the ability to include
+correlation effects has profound consequences on our predictive power of the
+MAE of strong magnets. Here we show that incorporating the local effects of
+electronic correlations with dynamical mean-field theory provides reliable
+estimates of the orbital moment, the mass enhancement and the MAE of YCo5.",1402.5543v2
+2015-01-14,Origin of the spin reorientation transitions in (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys,"Low-temperature measurements of the magnetocrystalline anisotropy energy $K$
+in (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys are reported, and the origin of this
+anisotropy is elucidated using a first-principles electronic structure
+analysis. The calculated concentration dependence $K(x)$ with a maximum near
+$x=0.3$ and a minimum near $x=0.8$ is in excellent agreement with experiment.
+This dependence is traced down to spin-orbital selection rules and the filling
+of electronic bands with increasing electronic concentration. At the optimal Co
+concentration, $K$ depends strongly on the tetragonality and doubles under a
+modest 3% increase of the $c/a$ ratio, suggesting that the magnetocrystalline
+anisotropy can be further enhanced using epitaxial or chemical strain.",1501.03483v2
+2015-03-16,Spin-fluctuation mechanism of anomalous temperature dependence of magnetocrystalline anisotropy in itinerant magnets,"The origins of the anomalous temperature dependence of magnetocrystalline
+anisotropy in (Fe$_{1-x}$Co$_{x}$)$_{2}$B alloys are elucidated using
+first-principles calculations within the disordered local moment model.
+Excellent agreement with experimental data is obtained. The anomalies are
+associated with the changes in band occupations due to Stoner-like band shifts
+and with the selective suppression of spin-orbit ""hot spots"" by thermal spin
+fluctuations. Under certain conditions, the anisotropy can increase, rather
+than decrease, with decreasing magnetization due to these peculiar electronic
+mechanisms, which contrast starkly with those assumed in existing models.",1503.04790v2
+2015-04-21,Tailoring the magnetodynamic properties of nanomagnets using magnetocrystalline and shape anisotropies,"Magnetodynamical properties of nanomagnets are affected by the demagnetizing
+fields created by the same nanoelements. In addition, magnetocrystalline
+anisotropy produces an effective field that also contributes to the spin
+dynamics. In this article we show how the dimensions of magnetic elements can
+be used to balance crystalline and shape anisotropies, and that this can be
+used to tailor the magnetodynamic properties. We study ferromagnetic ellipses
+patterned from a 10 nm thick epitaxial Fe film with dimensions ranging from 50
+x 150 nm to 150 x 450 nm. The study combines ferromagnetic resonance (FMR)
+spectroscopy with analytical calculations and micromagnetic simulations, and
+proves that the dynamical properties can be effectively controlled by changing
+the size of the nanomagnets. We also show how edge defects in the samples
+influence the magnetization dynamics. Dynamical edge modes localized along the
+sample edges are strongly influenced by edge defects, and this needs to be
+taken into account in understanding the full FMR spectrum",1504.05404v2
+2017-03-04,Impact of Anisotropy on Antiferromagnet Rotation in Heusler-type Ferromagnet/Antiferromagnet Epitaxial Bilayers,"We report the magnetotransport properties of ferromagnet (FM)/antiferromagnet
+(AFM) Fe$_2$CrSi/Ru$_2$MnGe epitaxial bilayers using current-in-plane
+configurations. Above the critical thickness of the Ru$_2$MnGe layer to induce
+exchange bias, symmetric and asymmetric curves were observed in response to the
+direction of FM magnetocrystalline anisotropy. Because each magnetoresistance
+curve showed full and partial AFM rotation, the magnetoresistance curves imply
+the impact of the Fe$_2$CrSi magnetocrystalline anisotropy to govern the AFM
+rotation. The maximum magnitude of the angular-dependent resistance-change
+ratio of the bilayers is more than an order of magnitude larger than that of
+single-layer Fe$_2$CrSi films, resulting from the reorientation of AFM spins
+via the FM rotation. These results highlight the essential role of controlling
+the AFM rotation and reveal a facile approach to detect the AFM moment even in
+current-in-plane configurations in FM/AFM bilayers.",1703.01406v2
+2017-05-09,"Ab initio study of magnetocrystalline anisotropy, magnetostriction, and Fermi surface of L10 FeNi (tetrataenite)","The ordered L1$_0$ FeNi phase (tetrataenite) is recently considered as a
+promising candidate for the rare-earth free permanent magnets applications. In
+this work we calculate several characteristics of the L1$_0$ FeNi, where most
+of the results come form the fully relativistic full potential FPLO method with
+the generalized gradient approximation (GGA). A special attention deserves the
+summary of the magnetocrystalline anisotropy energies (MAE's), the full
+potential calculations of the anisotropy constant $K_3$, and the combined
+analysis of the Fermi surface and three-dimensional $\mathbf{k}$-resolved MAE.
+Other calculated parameters presented in this article are the magnetic moments
+$m_{s}$ and $m_{l}$, magnetostrictive coefficient $\lambda_{001}$, bulk modulus
+B$_0$, and lattice parameters. The MAE's summary shows rather big discrepancies
+between the experimental MAE's from literature and also between the calculated
+MAE's.",1705.03371v2
+2017-06-22,Magnetocrystalline anisotropy in YCo5 and LaCo5: A choice of correlation parameters and the relativistic effects,"The dependence of the magnetocrystalline anisotropy energy (MAE) of MCo5 (M =
+Y, La) on the Coulomb correlations and strength of spin orbit (SO) interaction
+within the GGA + U scheme is investigated. A range of parameters suitable for
+the satisfactory description of key magnetic properties is determined. The
+origin of MAE in these materials is mostly related to the large orbital moment
+anisotropy of Co atoms on the 2c crystallographic site. Dependence of
+relativistic effects on Coulomb correlations, applicability of the second order
+perturbation theory for the description of MAE and effective screening of the
+SO interaction in these systems are discussed using a generalized virial
+theorem.",1706.07368v1
+2017-08-30,Micrometer thick soft magnetic films with magnetic moments restricted strictly in plane by negative magnetocrystalline anisotropy,"Stripe domains or any other type domain structures with part of their
+magnetic moments deviating from the film plane, which usually occur above a
+certain film thickness, are known problems that limit their potential
+applications for soft magnetic thin films (SMTFs). In this work, we report the
+growth of micrometer thick c-axis oriented hcp-Co84Ir16 SMTFs with their
+magnetic moments restricted strictly in plane by negative magnetocrystalline
+anisotropy. Extensive characterizations have been performed on these films,
+which show that they exhibit very good soft magnetic properties even for our
+micrometer thick films. Moreover, the anisotropy properties and high-frequency
+properties were thoroughly investigated and our results show very promising
+properties of these SMTFs for future applications.",1708.09179v1
+2017-12-06,First-principles investigation of magnetocrystalline anisotropy oscillations in Co$_{2}$FeAl/Ta heterostructures,"We report first-principles investigations of magnetocrystalline anisotropy
+energy (MCAE) oscillations as a function of capping layer thickness in Heusler
+alloy Co\textsubscript{2}FeAl/Ta heterostructures. Substantial oscillation is
+observed in FeAl-interface structure. According to $k$-space and
+band-decomposed charge density analyses, this oscillation is mainly attributed
+to the Fermi-energy-vicinal quantum well states (QWS) which are confined
+between Co\textsubscript{2}FeAl/Ta interface and Ta/vacuum surface. The smaller
+oscillation magnitude in the Co-interface structure can be explained by the
+smooth potential transition at the interface. These findings clarify that MCAE
+in Co\textsubscript{2}FeAl/Ta is not a local property of the interface and that
+the quantum well effect plays a dominant role in MCAE oscillations of the
+heterostructures. This work presents the possibility of tuning MCAE by QWS in
+capping layers, and paves the way for artificially controlling magnetic
+anisotropy energy in magnetic tunnel junctions.",1712.02139v2
+2018-08-02,Exchange interactions and Curie temperature of Ce-substituted SmCo5,"A partial substitution of Sm by Ce can have drastic effects on the magnetic
+performance, because it will introduce strain in the structure and breaks the
+lattice symmetry in a way that enhances the contribution of the Co atoms to
+magnetocrystalline anisotropy. However, Ce substitutions, which are benefit to
+improve the magnetocrystalline anisotropy, are detrimental to enhance the Curie
+temperature (TC). With the requirements of wide operating temperature range of
+magnetic devices, it is important to quantitatively explore the relationship
+between the TC and ferromagnetic exchange energy. In this paper we show, based
+on mean-field approximation, that Ce substitution-induced tensile strain in
+SmCo5 leads to enhanced effective ferromagnetic exchange energy and TC while Ce
+atom itself reduces TC.",1808.00988v1
+2019-02-03,Design of Face Centered Cubic Co81.8Si9.1B9.1 with High Magnetocrystalline Anisotropy,"Despite the composition close to glassy forming alloys, face centered cubic
+(FCC) Co81.8Si9.1B9.1, designed based on Co9B atomic cluster (polyhedral), are
+synthesized as singlephase ribbons successfully. These ribbons, with grain
+sizes of ca. 92 nm, show supreme ductility and strong orientation along (111),
+which couples with shape anisotropy leading to high magnetocrystalline
+anisotropy comparable to Co rich Co-Pt nanoscale thin films, with a coercivity
+of 430 Oe and squareness of 0.82 at room temperature. The stability and
+magnetic behaviors of the phase are discussed based on experimental electronic
+structure. This work not only develops low cost Co-based materials for hard
+magnetic applications, but also extends the atomic cluster model developed for
+amorphous alloys into the design of new crystalline materials.",1902.05120v1
+2019-10-16,"Temperature-dependent magnetocrystalline anisotropy of rare earth/transition metal permanent magnets from first principles: The light RCo$_5$ (R=Y, La-Gd) intermetallics","Computational design of more efficient rare earth/transition metal (RE-TM)
+permanent magnets requires accurately calculating the magnetocrystalline
+anisotropy (MCA) at finite temperature, since this property places an upper
+bound on the coercivity. Here, we present a first-principles methodology to
+calculate the MCA of RE-TM magnets which fully accounts for the effects of
+temperature on the underlying electrons. The itinerant electron TM magnetism is
+described within the disordered local moment picture, and the localized RE-4f
+magnetism is described within crystal field theory. We use our model, which is
+free of adjustable parameters, to calculate the MCA of the RCo$_5$ (R=Y, La-Gd)
+magnet family for temperatures 0--600 K. We correctly find a huge uniaxial
+anisotropy for SmCo$_5$ (21.3 MJm$^{-3}$ at 300 K) and two finite temperature
+spin reorientation transitions for NdCo$_5$. The calculations also demonstrate
+dramatic valency effects in CeCo$_5$ and PrCo$_5$. Our calculations provide
+quantitative, first-principles insight into several decades of RE-TM
+experimental studies.",1910.07436v1
+2019-11-04,DFT+U Investigation of magnetocrystalline anisotropy of Mn-doped transition-metal dichalcogenides monolayers,"Doped transition-metal dichalcogenides monolayers exhibit exciting magnetic
+properties for the benefit of two-dimensional spintronic devices. Using density
+functional theory (DFT) incorporating Hubbard-type of correction (DFT$+U$) to
+account for the electronic correlation, we study the magnetocrystalline
+anisotropy energy (MAE) characterizing Mn-doped MS$_2$ (M=Mo, W) monolayers. A
+single isolated Mn dopant exhibits a large perpendicular magnetic anisotropy of
+35 meV (8 meV) in the case of Mn-doped WS$_2$ (MoS$_2$) monolayer. This value
+originates from the Mn in-plane orbitals degeneracy lifting due to the
+spin-orbit coupling. In pairwise doping, the magnetization easy axis changes to
+the in-plane direction with a weak MAE compared to single Mn doping. Our
+results suggest that diluted Mn-doped MS$_2$ monolayers, where the Mn dopants
+are well separated, could potentially be a candidate for the realization of
+ultimate nanomagnet units.",1911.01173v2
+2019-12-06,Understanding the origin of magnetocrystalline anisotropy in pure and Fe/Si substituted SmCo5,"We report magnetocrystalline anisotropy of pure and Fe/Si substituted SmCo5.
+The calculations were performed using the advanced density functional theory
+(DFT) including onsite electron-electron correlation and spin orbit coupling.
+Si substitution substantially reduces both uniaxial magnetic anisotropy and
+magnetic moment. Fe substitution with the selective site, on the other hand,
+enhances the magnetic moment with limited chemical stability. The magnetic
+hardness of SmCo5 is governed by Sm 4f localized orbital contributions, which
+get flatten and split with the substitution of Co (2c) with Si/Fe atoms, except
+the Fe substitution at 3g site. It is also confirmed that Si substitutions
+favor the thermodynamic stability on the contrary to diminishing the magnetic
+and anisotropic effect in SmCo5 at either site.",1912.03368v1
+2020-09-02,"Phase transition in the magnetocrystalline anisotropy of tetragonal Heusler alloys: Rh$_2T$Sb, $T=$ Fe, Co","This work reports on first principles calculations of the electronic and
+magnetic structure of tetragonal Heusler compounds with the composition
+Rh$_2$Fe$_{x}$Co$_{1-x}$Sb ($0\leq x\leq1$). It is found that the magnetic
+moments increase from 2 to 3.4~$\mu_B$ and the Curie temperature decreases from
+500 to 464~K with increasing Fe content $x$. The $3d$ transition metals make
+the main contribution to the magnetic moments, whereas Rh contributes only
+approximately 0.2~$\mu_B$ per atom, independent of the composition. The paper
+focuses on the magnetocrystalline anisotropy of the borderline compounds
+Rh$_2$FeSb, Rh$_2$Fe$_{0.5}$Co$_{0.5}$Sb, and Rh$_2$CoSb. A transition from
+easy-axis to easy-plane anisotropy is observed when the composition changes
+from Rh$_2$CoSb to Rh$_2$FeSb. The transition occurs at an iron concentration
+of approximately 40\%.",2009.00920v1
+2021-06-16,Towards hexagonal $C_{2v}$ systems with anisotropic DMI: Characterization of epitaxial Co$(10\bar{1}0)$/Pt$(110)$ multilayer films,"Ferromagnet/heavy metal (FM/HM) multilayer thin films with $C_{2v}$ symmetry
+have the potential to host antiskyrmions and other chiral spin textures via an
+anisotropic Dzyaloshinkii-Moriya interaction (DMI). Here, we present a
+candidate material system that also has a strong uniaxial magnetocrystalline
+anisotropy aligned in the plane of the film. This system is based on a new
+Co/Pt epitaxial relationship, which is the central focus of this work:
+hexagonal closed-packed Co$(10\bar{1}0)[0001]$ $\parallel$ face-centered cubic
+Pt$(110)[001]$. We characterized the crystal structure and magnetic properties
+of our films using X-ray diffraction techniques and magnetometry respectively,
+including q-scans to determine stacking fault densities and their correlation
+with the measured magnetocrystalline anisotropy constant and thickness of Co.
+In future ultrathin multilayer films, we expect this epitaxial relationship to
+further enable an anisotropic DMI while supporting interfacial perpendicular
+magnetic anisotropy. The anticipated confluence of these properties, along with
+the tunability of multilayer films, make this material system a promising
+testbed for unveiling new spin configurations in FM/HM films.",2106.10249v2
+2021-07-23,Reduced magnetocrystalline anisotropy of CoFe$_2$O$_4$ thin films studied by angle-dependent x-ray magnetic circular dichroism,"Spinel-type CoFe$_2$O$_4$ is a ferrimagnetic insulator with the N\'eel
+temperature exceeding 790 K, and shows a strong cubic magnetocrystalline
+anisotropy (MCA) in bulk materials. However, when a CoFe$_2$O$_4$ film is grown
+on other materials, its magnetic properties are degraded so that so-called
+magnetically dead layers are expected to be formed in the interfacial region.
+We investigate how the magnetic anisotropy of CoFe$_2$O$_4$ is modified at the
+interface of CoFe$_2$O$_4$/Al$_2$O$_3$ bilayers grown on Si(111) using x-ray
+magnetic circular dichroism (XMCD). We find that the thinner CoFe$_2$O$_4$
+films have significantly smaller MCA values than bulk materials. The reduction
+of MCA is explained by the reduced number of Co$^{2+}$ ions at the $O_h$ site
+reported by a previous study [Y. K. Wakabayashi $\textit{et al.}$, Phys. Rev. B
+$\textbf{96}$, 104410 (2017)].",2107.11204v1
+2023-02-28,Bistable electric field control of single-atom magnetocrystalline anisotropy,"We reversibly switch the polar environment of an individual magnetic atom
+with an electric field to control the energy barrier for reversal of
+magnetization. By applying an electric field in the gap between the tip and
+sample of a scanning tunneling microscope, we induce bistable changes in the
+polarization of the region surrounding a chlorine vacancy in a monolayer of
+sodium chloride on copper terminated by a monolayer of copper nitride. The
+displacement of the sodium chloride ions alters the local electric polarization
+and modifies the magnetocrystalline anisotropy experienced by a single cobalt
+atom. When a cobalt atom is near a chlorine vacancy, spin-sensitive inelastic
+electron tunneling spectroscopy measurements can reveal the change in
+anisotropy. The demonstration of atomic-scale control of magnetic properties
+with electric fields opens new possibilities for probing the origins of
+magnetoelectric coupling and will stimulate the development of model artificial
+mutliferroic systems.",2302.14667v1
+2015-05-21,General Formalism for Magnetic Anisotropy Constants,"Direct expressions for the magnetic anisotropy constants are given at a
+finite temperature from microscopic viewpoints. In the present derivation, it
+is assumed that the Hamiltonian is a linear function with respect to the
+magnetization direction. We discuss in detail the first-order constant $K_1$
+and show that the results reproduce previous results. We also apply our method
+to Nd$_2$Fe$_{14}$B compounds and demonstrate that the temperature dependencies
+of the magnetocrystalline anisotropy constants $K_1$, $K_2$, and $K_3$ are
+successfully computed.",1505.05686v1
+2016-05-23,Large magnetic anisotropy in Fe_{0.25}TaS_2,"We present a first-principles study of the large magneto-crystalline
+anisotropy in the intercalated di-chalcogenide material \ce{Fe_{0.25}TaS_2},
+investigated with the DFT+U approach. We verify a uniaxial magnetocrystalline
+anisotropy energy(MAE) of 15meV/Fe. in the material. We further analyze the
+dependence of MAE on the constituent elements and the effect of spin-orbit
+coupling. Contrary to conventional intuition, we find a small contribution to
+MAE due to strong spin-orbit coupling in the heavier element, Ta. We show that
+the electronic configuration, crystal field environment and correlational
+effects of the magnetic ion are more important.",1605.07141v1
+2018-07-24,Pushing the limits of magnetic anisotropy in the Sm-Co system,"Materials based on the Sm-Co system exhibit remarkable magnetic performance
+due to their high Curie temperature, large saturation magnetization, and strong
+magnetic anisotropy, which are the result of the electronic structure in Co and
+Sm and their arrangement in the hexagonal lattice. In this paper we show, using
+first-principles calculations, mean-field theory, and atomistic Monte Carlo
+simulations that slight modifications of the SmCo5 crystal structure, induced
+by strain or partial substitution of Sm by Ce, change the exchange interaction
+energy and increase the magnetocrystalline anisotropy energy drastically. This
+finding shows how small changes in local-structure environments lead to
+substantial changes in macroscopic properties and enables the optimization of
+high-performance materials at the atomic level.",1807.09257v1
+2023-07-07,Anomalous Nernst effect in perpendicularly magnetised τ-MnAl thin films,"$\tau$-MnAl is interesting for spintronic applications as a ferromagnet with
+perpendicular magnetic anisotropy due to its high uniaxial magnetocrystalline
+anisotropy. Here we report on the anomalous Nernst effect of sputter deposited
+$\tau$-MnAl thin films. We demonstrate a robust anomalous Nernst effect at
+temperatures of 200 K and 300 K with a hysteresis similar to the anomalous Hall
+effect and the magnetisation of the material. The anomalous Nernst coefficient
+of (0.6$\pm$0.24) $\mu$V/K at 300 K is comparable to other perpendicular
+magnetic anisotropy thin films. Therefore $\tau$-MnAl is a promising candidate
+for spin-caloritronic research.",2307.03458v1
+2016-11-20,The effect of dynamical compressive and shear strain on magnetic anisotropy in low symmetry ferromagnetic film,"Dynamical strain generated upon excitation of a metallic film by a
+femtosecond laser pulse may become a versatile tool enabling control of
+magnetic state of thin films and nanostructures via inverse magnetostriction on
+a picosecond time scale. Here we explore two alternative approaches to
+manipulate magnetocrystalline anisotropy and excite magnetization precession in
+a low-symmetry film of a magnetic metallic alloy galfenol (Fe,Ga) either by
+injecting picosecond strain pulse into it from a substrate or by generating
+dynamical strain of complex temporal profile in the film directly. In the
+former case we realize ultrafast excitation of magnetization dynamics solely by
+strain pulses. In the latter case optically-generated strain emerged abruptly
+in the film modifies its magnetocrystalline anisotropy, competing with
+heat-induced change of anisotropy parameters. We demonstrate that the
+optically-generated strain remains efficient for launching magnetization
+precession, when the heat-induced changes of anisotropy parameters do not
+trigger the precession anymore. We emphasize that in both approaches the
+ultrafast change of magnetic anisotropy mediating the precession excitation
+relies on mixed, compressive and shear, character of the dynamical strain,
+which emerges due to low-symmetry of the metallic film under study.",1611.06599v3
+2017-07-10,Giant interfacial perpendicular magnetic anisotropy in Fe/CuIn$_{1-x}$Ga$_x$Se$_2$ beyond Fe/MgO,"We study interfacial magnetocrystalline anisotropies in various
+Fe/semiconductor heterostructures by means of first-principles calculations. We
+find that many of those systems show perpendicular magnetic anisotropy (PMA)
+with a positive value of the interfacial anisotropy constant $K_{\rm i}$. In
+particular, the Fe/CuInSe$_2$ interface has a large $K_{\rm i}$ of $\sim
+2.3\,{\rm mJ/m^2}$, which is about 1.6 times larger than that of Fe/MgO known
+as a typical system with relatively large PMA. We also find that the values of
+$K_{\rm i}$ in almost all the systems studied in this work follow the
+well-known Bruno's relation, which indicates that minority-spin states around
+the Fermi level provide dominant contributions to the interfacial
+magnetocrystalline anisotropies. Detailed analyses of the local density of
+states and wave-vector-resolved anisotropy energy clarify that the large
+$K_{\rm i}$ in Fe/CuInSe$_2$ is attributed to the preferable $3d$-orbital
+configurations around the Fermi level in the minority-spin states of the
+interfacial Fe atoms. Moreover, we have shown that the locations of interfacial
+Se atoms are the key for such orbital configurations of the interfacial Fe
+atoms.",1707.02694v3
+2021-11-03,Anisotropic magnetocaloric effect of CrI$_{3}$: A theoretical study,"CrI$_{3}$ is considered to be a promising candidate for spintronic devices
+and data storage. We derived the Heisenberg Hamiltonian for CrI$_{3}$ from
+density functional calculations using the Liechtenstein formula. Moreover, the
+Monte--Carlo simulations with the Sucksmith--Thompson method were performed to
+analyze the effect of magnetic anisotropy energy on the thermodynamic
+properties. Our method successfully reproduced the negative sign of isothermal
+magnetic entropy changes when a magnetic field was applied along the hard
+plane. We found that the temperature dependence of the magnetocrystalline
+anisotropy energy is not negligible at temperatures slightly above the Curie
+temperature. We clarified that the origin of this phenomenon is attributed to
+anisotropic magnetic susceptibility and magnetization anisotropy. The
+difference between the entropy change of the easy axis and the hard plane is
+proportional to the temperature dependence of the magnetic anisotropy energy,
+implying that the anisotropic entropy term is the main source of the
+temperature dependence of the free energy difference when magnetizing in a
+specific direction other than the easy axis. We also investigated the magnetic
+susceptibility that can be used for the characterization of the negative sign
+of the entropy change in the case of a hard plane. The competition of
+magnetocrystalline anisotropy energy and external magnetic field at low
+temperature and low magnetic field region causes a high magnetic susceptibility
+as the fluctuation of magnetization. Meanwhile, the anisotropy energy is
+suppressed at a sufficient magnetic field applied along the hard axis, the
+magnetization is fully rotated to the direction of the external magnetic field.",2111.02063v1
+2016-05-18,Interfacial magnetic anisotropy from a 3-dimensional Rashba substrate,"We study the magnetic anisotropy which arises at the interface between a thin
+film ferromagnet and a 3-d Rashba material. The 3-d Rashba material is
+characterized by the spin-orbit strength $\alpha$ and the direction of broken
+bulk inversion symmetry $\hat n$. We find an in-plane uniaxial anisotropy in
+the $\hat{z}\times\hat{n}$ direction, where $\hat z$ is the interface normal.
+For realistic values of $\alpha$, the uniaxial anisotropy is of a similar order
+of magnitude as the bulk magnetocrystalline anisotropy. Evaluating the uniaxial
+anisotropy for a simplified model in 1-d shows that for small band filling, the
+in-plane easy axis anisotropy scales as $\alpha^4$ and results from a twisted
+exchange interaction between the spins in the 3-d Rashba material and the
+ferromagnet. For a ferroelectric 3-d Rashba material, $\hat n$ can be
+controlled with an electric field, and we propose that the interfacial magnetic
+anisotropy could provide a mechanism for electrical control of the magnetic
+orientation.",1605.05739v1
+2016-07-21,Perpendicular magnetic anisotropy of two-dimensional Rashba ferromagnets,"We compute the magnetocrystalline anisotropy energy within two-dimensional
+Rashba models. For a ferromagnetic free-electron Rashba model, the magnetic
+anisotropy is exactly zero regardless of the strength of the Rashba coupling,
+unless only the lowest band is occupied. For this latter case, the model
+predicts in-plane anisotropy. For a more realistic Rashba model with finite
+band width, the magnetic anisotropy evolves from in-plane to perpendicular and
+back to in-plane as bands are progressively filled. This evolution agrees with
+first-principles calculations on the interfacial anisotropy, suggesting that
+the Rashba model captures energetics leading to anisotropy originating from the
+interface provided that the model takes account of the finite Brillouin zone.
+The results show that the electron density modulation by doping or an external
+voltage is more important for voltage-controlled magnetic anisotropy than the
+modulation of the Rashba parameter.",1607.06470v2
+2020-02-10,On the anisotropies of magnetization and electronic transport of magnetic Weyl semimetal Co3Sn2S2,"Co3Sn2S2, a quasi-two-dimensional system with kagome lattice, has been found
+as a magnetic Weyl semimetal recently. In this work, the anisotropies of
+magnetization and transport properties of Co3Sn2S2 were investigated. The high
+field measurements reveal a giant magnetocrystalline anisotropy with an
+out-of-plane saturation field of 0.9 kOe and an in-plane saturation field of
+230 kOe at 2 K, showing a magnetocrystalline anisotropy coefficient Ku up to
+8.3 * 10^5 J m-3, which indicates that it is extremely difficult to align the
+small moment of 0.29 {\mu}B/Co on the kagome lattice from c axis to ab plane.
+The out-of-plane angular dependences of Hall conductivity further reveal strong
+anisotropies in Berry curvature and ferromagnetism, and the vector directions
+of both are always parallel with each other. For in-plane situation, the
+longitudinal and transverse measurements for both I parallel a and I
+perpendicular a cases show that the transport on the kagome lattice is
+isotropic. These results provide essential understanding on the magnetization
+and transport behaviors for the magnetic Weyl semimetal Co3Sn2S2.",2002.03940v1
+2006-01-26,"Magnetic anisotropy switching in (Ga,Mn)As with increasing hole concentration","We study a possible mechanism of the switching of the magnetic easy axis as a
+function of hole concentration in (Ga,Mn)As epilayers. In-plane uniaxial
+magnetic anisotropy along [110] is found to exceed intrinsic cubic
+magnetocrystalline anisotropy above a hole concentration of p = 1.5 * 10^21
+cm^-3 at 4 K. This anisotropy switching can also be realized by post-growth
+annealing, and the temperature-dependent ac susceptibility is significantly
+changed with increasing annealing time. On the basis of our recent scenario
+[Phys. Rev. Lett. 94, 147203 (2005); Phys. Rev. B 73, 155204 (2006).], we
+deduce that the growth of highly hole-concentrated cluster regions with [110]
+uniaxial anisotropy is likely the predominant cause of the enhancement in [110]
+uniaxial anisotropy at the high hole concentration regime. We can clearly rule
+out anisotropic lattice strain as a possible origin of the switching of the
+magnetic anisotropy.",0601603v2
+1996-05-22,Theory of Magnetocrystalline Anisotropy Energy for Wires and Corrals of Fe adatoms: A Non-Perturbative Theory,"The magnetocrystalline anisotropy energy $E_{anis}$ for free-standing chains
+(quantum wires) and rings (quantum corrals) of Fe-adatoms $N=$(2...48) is
+determined using an electronic tight-binding theory. Treating spin-orbit
+coupling non-perturbatively, we analyze the relationship between the electronic
+structure of the Fe $d$-electrons and $E_{anis}(n_{d})$, for both the chain and
+ring conformations. We find that $E_{anis}(N)$ is larger for wires than for
+rings or infinite monolayers. Generally $E_{anis}(n_{d})$ decreases in chains
+upon increasing $N$, while for rings $E_{anis}(n_{d})$ is essentially
+independent of $N$. For increasing $N$, $E_{anis}(n_{d})$ in corrals approaches
+the results for freestanding monolayers. Small rings exhibit clear odd-even
+oscillations of $E_{anis}(N)$. Within our theoretical framework we are able to
+explain the experimentally observed oscillations of $E_{anis}(n_{d})$ during
+film growth with a period of one monolayer. Finally, a generalization of Hund's
+third rule on spin-orbit coupling to itinerant ferromagnets is proposed.",9605137v1
+2000-01-13,Ab-initio Theoretical Description of the Interrelation between Magnetocrystalline Anisotropy and Atomic Short-Range Order,"The cubic lattice symmetry of ferromagnetic homogeneously disordered alloys
+is when a compositional modulation is imposed. This can have a profound
+influence on the magnetocrystalline anisotropy energy (MAE). We describe our
+ab-initio theory of this effect and use the framework of concentration waves
+with the electronic structure described within the spin-polarised relativistic
+Korringa-Kohn-Rostoker coherent-potential approximation. We find that ordering
+produces a 2 order of magnitude increase in the MAE as well as altering the
+equilibrium direction of magnetisation. Using the same theoretical framework we
+also examine directional compositional order produced by magnetic annealing
+with an explicit study of permalloy.",0001181v1
+2010-01-09,Correlation induced half-metallicity in a ferromagnetic single-layered compound: Sr$_2$CoO$_4$,"The electronic and magnetic properties of Sr$_2$CoO$_4$ compound have been
+studied using $\emph{ab initio}$ electronic structure calculations. As opposed
+to GGA calculation, which gives ferromagnetic metallic solution, GGA+$U$
+calculations provide two kind of ferromagnetic solutions: (i) half-metallic and
+(ii) metallic. The half-metallic solution is a ground state of the system and
+the metallic one is a metastable state. The strong hybridization between Co
+3$d$ and O 2$p$ orbitals decides the electronic and magnetic properties of the
+compound. The total magnetic moment per formula unit is found to be $\sim$ 3
+$\mu_B$ ($S$ = 3/2). Our calculations give the magnetocrystalline anisotropy
+energy of $\sim$ 2.7 meV, which provides a good description of experimentally
+observed large magnetocrystalline anisotropy. The Heisenberg exchange
+parameters up to fourth nearest neighbours are also calculated. The mean-field
+theory gives the $T_C$ = 887 K. The possible physical implications of the
+ferromagnetic half-metallic ground state are also discussed.",1001.1405v1
+2010-03-11,High-temperature multiferroicity and strong magnetocrystalline anisotropy in 3d-5d double perovskites,"Using density functional calculations we explore the properties of
+as-yet-unsynthesized $3d - 5d$ ordered double perovskites ($A_2BB'$O$_6$) with
+highly polarizable Bi$^{3+}$ ions on the $A$ site. We find that the
+Bi$_2$NiReO$_6$ and Bi$_2$MnReO$_6$ compounds are insulating and exhibit a
+robust net magnetization that persists above room temperature. When the
+in-plane lattice vectors of the pseudocubic unit cell are constrained to be
+orthogonal (for example, by coherent heteroepitaxy), the ground states are
+ferroelectric with large polarization and a very large uniaxial
+magnetocrystalline anisotropy with easy axis along the ferroelectric
+polarization direction. Our results suggest a route to multiferroism and
+electrically controlled magnetization orientation at room temperature.",1003.2449v2
+2011-11-17,"Theory of magnetization precession induced by a picosecond strain pulse in ferromagnetic semiconductor (Ga,Mn)As","A theoretical model of the coherent precession of magnetization excited by a
+picosecond acoustic pulse in a ferromagnetic semiconductor layer of (Ga,Mn)As
+is developed. The short strain pulse injected into the ferromagnetic layer
+modifies the magnetocrystalline anisotropy resulting in a tilt of the
+equilibrium orientation of magnetization and subsequent magnetization
+precession. We derive a quantitative model of this effect using the
+Landau-Lifshitz equation for the magnetization that is precessing in the
+time-dependent effective magnetic field. After developing the general
+formalism, we then provide a numerical analysis for a certain structure and two
+typical experimental geometries in which an external magnetic field is applied
+either along the hard or the easy magnetization axis. As a result we identify
+three main factors, which determine the precession amplitude: the
+magnetocrystalline anisotropy of the ferromagnetic layer, its thickness, and
+the strain pulse parameters.",1111.4043v1
+2012-06-27,Effect of Pt impurities on the magnetocrystalline anisotropy of hcp Co: a first-principles study,"In terms of the fully relativistic screened Korringa-Kohn-Rostoker method we
+investigate the variation in the magnetocrystalline anisotropy energy (MAE) of
+hexagonal close-packed cobalt with the addition of platinum impurities. In
+particular, we perform calculations on a bulk cobalt system in which one of the
+atomic layers contains a fractional, substitutional platinum impurity. Our
+calculations show that at small concentrations of platinum the MAE is reduced,
+while at larger concentrations the MAE is enhanced. This change of the MAE can
+be attributed to an interplay between on-site Pt MAE contributions and induced
+MAE contributions on the Co sites. The latter ones are subject to pronounced,
+long-ranged Friedel-oscillations that can lead to significant size effects in
+the experimental determination of the MAE of nano-sized samples.",1206.6200v1
+2013-04-04,Effect of stacking faults on the magnetocrystalline anisotropy of hcp Co: a first-principles study,"In terms of the fully relativistic screened Korringa-Kohn-Rostoker method we
+investigate the effect of stacking faults on the magnetic properties of
+hexagonal close-packed cobalt. In particular, we consider the formation energy
+and the effect on the magnetocrystalline anisotropy energy (MAE) of four
+different stacking faults in hcp cobalt -- an intrinsic growth fault, an
+intrinsic deformation fault, an extrinsic fault and a twin-like fault. We find
+that the intrinsic growth fault has the lowest formation energy, in good
+agreement with previous first-principles calculations. With the exception of
+the intrinsic deformation fault which has a positive impact on the MAE, we find
+that the presence of a stacking fault generally reduces the MAE of bulk Co.
+Finally, we consider a pair of intrinsic growth faults and find that their
+effect on the MAE is not additive, but synergic.",1304.1353v1
+2013-04-19,Effects of composition and chemical disorder on the magnetocrystalline anisotropy of Fe_{x}Pt_{1-x} alloys,"We perform first principles calculations of the magnetocrystalline anisotropy
+energy (MAE) of the L1_{0}-like Fe_{x}Pt_{1-x} samples studied experimentally
+by Barmak and co-workers in [J. Appl. Phys. 98 (2005) 033904]. The variation of
+composition and long-range chemical order in the samples was studied in terms
+of the coherent potential approximation. In accordance with experimental
+observations, we find that, in the presence of long-range chemical disorder,
+Fe-rich samples exhibit a larger MAE than stoichiometric FePt. By considering
+the site- and species-resolved contributions to the MAE, we infer that the MAE
+is primarily a function of the degree of completeness of the nominal Fe layers
+in the L1_{0} FePt structure.",1304.5323v1
+2014-04-28,Electronic structure and magnetic properties of L1_0 binary alloys,"We present a systematic study of the magnetic properties of L1$_0$ binary
+alloys FeNi, CoNi, MnAl and MnGa via two different density functional theory
+approaches. Our calculations show large magnetocrystalline anisotropies in the
+order $1~\text{MJ/m}^3$ or higher for CoNi, MnAl and MnGa while FeNi shows a
+somewhat lower value in the range $0.48 - 0.77 ~\text{MJ/m}^3$. Saturation
+magnetization values of $1.3~\text{MA/m}$, $1.0~\text{MA/m}$, $0.8~\text{MA/m}$
+and $0.9~\text{MA/m}$ are obtained for FeNi, CoNi, MnAl and MnGa respectively.
+Curie temperatures are evaluated via Monte Carlo simulations and show
+$T_\text{C}=916~\text{K}$ and $T_\text{C}=1130~\text{K}$ for FeNi and CoNi
+respectively. For Mn-based compounds Mn-rich off-stoichiometric compositions
+are found to be important for the stability of a ferro or ferrimagnetic ground
+state with $T_\text{C}$ greater than $600~\text{K}$. The effect of
+substitutional disorder is studied and found to decrease both
+magnetocrystalline anisotropies and Curie temperatures in FeNi and CoNi.",1404.7097v2
+2014-05-02,Jahn-Teller driven perpendicular magnetocrystalline anisotropy in metastable Ruthenium,"A new metastable phase of the body-centered-tetragonal ruthenium ({\em
+bct}--Ru) is identified to exhibit a large perpendicular magnetocrystalline
+anisotropy (PMCA), whose energy, $E_{MCA}$, is as large as 150 $\mu$eV/atom,
+two orders of magnitude greater than those of 3$d$ magnetic metals. Further
+investigation over the range of tetragonal distortion suggests that the
+appearance of the magnetism in the {\em bct}--Ru is governed by the Jahn-Teller
+spit $e_g$ orbitals. Moreover, from band analysis, MCA is mainly determined by
+an interplay between two $e_g$ states, $d_{x^2-y^2}$ and $d_{z^2}$ states, as a
+result of level reversal associated with tetragonal distortion.",1405.0499v3
+2017-12-27,Effective reduction of the coercivity for Co$_{72}$Pt$_{28}$ thin film by exchange coupled Co$_{81}$Ir$_{19}$ soft layer with negative magnetocrystalline anisotropy,"We report on the investigation of coercivity changes of the
+Co$_{72}$Pt$_{28}$/Co$_{81}$Ir$_{19}$ exchange-coupled composite (ECC) media
+with negative soft-layer (SL) magnetocrystalline anisotropy (MA) . Our results
+show that the hard-layer (HL) of our sample exhibits a columnar type
+microstructure with well isolated grains and the SL with hcp-structure grows on
+top of the HL with the same texture. Therefore, strong coupling of the two
+layers have been realized as evidenced by the magnetic characterization.
+Importantly, we observe a more effective reduction of the coercivity of the ECC
+media by using SLs with negative MA when compared to the use of SLs with
+positive or negligible MA. The experimental results are corroborated by
+theoretical calculations.",1712.09504v1
+2018-01-25,Heusler compounds -- how to tune the magnetocrystalline anisotropy,"Tailoring and controlling magnetic properties is an important factor for
+materials design. Here, we present a case study for Ni-based Heusler compounds
+of the type Ni$_2$YZ with Y = Mn, Fe, Co and Z = B, Al, Ga, In, Si, Ge, Sn
+based on first principles electronic structure calculations. These compounds
+are interesting since the materials properties can be quite easily tuned by
+composition and many of them possess a non-cubic ground state being a
+prerequisite for a finite magnetocrystalline anisotropy (MAE). We discuss
+systematically the influence of doping at the Y and Z sublattice as well of
+lattice deformation on the MAE. We show that in case of Ni$_2$CoZ the phase
+stability and the MAE can be improved using quaternary systems with elements
+from group 13 and 14 on the Z sublattice whereas changing the Y sublattice
+occupation by adding Fe does not lead to an increase of the MAE. Furthermore,
+we studied the influence of the lattice ratio on the MAE. Showing that small
+deviations can lead to a doubling of the MAE as in case of Ni$_2$FeGe. Even
+though we demonstrate this for a limited set of systems the findings may carry
+over to other related systems.",1801.08511v1
+2018-06-05,Efficient technique for ab-initio calculation of magnetocrystalline anisotropy energy,"Ab-initio calculation of magnetocrystalline anisotropy energy (MCAE) often
+requires a strict convergence criterion and a dense k-point mesh to sample the
+Brillouin zone, making its convergence problematic and time-consuming. The
+force theorem for MCAE states that MCAE can be calculated by the band energy
+difference between two magnetization directions at a fixed potential. The
+maximally localized Wannier function can be utilized to construct a compact
+Hilbert space of low-lying electron states and interpolate band eigenvalues
+with high precession. We combine the force theorem and the Wannier
+interpolation of eigenvalues together to improve the efficiency of MCAE
+calculations with no loss of accuracy. We use a Fe chain, a Fe monolayer and a
+FeNi alloy as examples and demonstrate that the Wannier interpolation method
+for MCAE is able to reduce the computational cost significantly and remain
+accurate simultaneously, compared with a direct ab-initio calculation on a very
+dense k-point mesh. This efficient Wannier interpolation approach makes it
+possible for large-scale and high-throughput MCAE calculations, which could
+benefit the design of spintronics devices.",1806.01536v2
+2018-07-19,Magnetocrystalline anisotropy in the Kondo lattice compound CeAgAs$_2$,"We report on the single crystal growth and anisotropic physical properties of
+CeAgAs$_2$. The compound crystallizes as on ordered variant of the
+HfCuSi$_2$-type crystal structure and adopts the orthorhombic space group
+$Pmca$~(\#57) with two symmetry inequivalent cerium atomic positions in the
+unit cell. The orthorhombic crystal structure of our single crystal was
+confirmed from the powder x-ray diffraction and from electron diffraction
+patterns obtained from the transmission electron microscope. The anisotropic
+physical properties have been investigated on a good quality single crystal by
+measuring the magnetic susceptibility, isothermal magnetization, electrical
+transport and heat capacity. The magnetic susceptibility and magnetization
+measurements revealed that this compound orders antiferromagnetically with two
+closely spaced magnetic transitions at $T_{\rm N1} = 6$~K and $T_{\rm N2} =
+4.9$~K. Magnetization studies have revealed a large magnetocrystalline
+anisotropy due to the crystalline electric field (CEF) with an easy axis of
+magnetization along the [010] direction. The magnetic susceptibility measured
+along the [001] direction exhibited a broad hump in the temperature range 50 to
+250~K, while typical Curie-Weiss behaviour was observed along the other two
+orthogonal directions. The electrical resistivity and the heat capacity
+measurements revealed that CeAgAs$_2$ is a Kondo lattice system with a magnetic
+ground state.",1807.07265v1
+2018-11-29,Response of the skyrmion lattice in MnSi to cubic magnetocrystalline anisotropies,"We report high-precision small angle neutron scattering of the orientation of
+the skyrmion lattice in a spherical sample of MnSi under systematic changes of
+the magnetic field direction. For all field directions the skyrmion lattice may
+be accurately described as a triple-$\vec{Q}$ state, where the modulus $\vert
+\vec{Q} \vert$ is constant and the wave vectors enclose rigid angles of
+$120^{\circ}$. Along a great circle across $\langle 100\rangle$, $\langle
+110\rangle$, and $\langle 111\rangle$ the normal to the skyrmion-lattice plane
+varies systematically by $\pm3^{\circ}$ with respect to the field direction,
+while the in-plane alignment displays a reorientation by $15^{\circ}$ for
+magnetic field along $\langle 100\rangle$. Our observations are qualitatively
+and quantitatively in excellent agreement with an effective potential, that is
+determined by the symmetries of the tetrahedral point group $T$ and includes
+contributions up to sixth-order in spin-orbit coupling, providing a full
+account of the effect of cubic magnetocrystalline anisotropies on the skyrmion
+lattice in MnSi.",1811.12439v1
+2019-02-05,Intersublattice magnetocrystalline anisotropy using a realistic tight-binding method based on maximally localized Wannier functions,"Using a realistic tight-binding Hamiltonian based on maximally localized
+Wannier functions, we investigate the two-ion magnetocrystalline anisotropy
+energy (MAE) in $L1_0$ transition metal compounds. MAE contributions from
+throughout the Brillouin zone are obtained using magnetic force theorem
+calculations with and without perturbation theory. The results from either
+method agree with one another, and both reflect features of the Fermi surface.
+The intra-sublattice and inter-sublattice contributions to MAE are evaluated
+using a Green's function method. We find that the sign of the inter-sublattice
+contribution varies among compounds, and that its amplitude may be significant,
+suggesting MAE can not be resolved accurately in a single-ion manner. The
+results are further validated by scaling spin-orbit-coupling strength in
+density functional theory. Overall, this realistic tight-binding method provide
+an effective approach to evaluate and analyze MAE while retaining the accuracy
+of corresponding first-principles methods.",1902.01561v2
+2019-08-06,Strain controllable magnetocrystalline anisotropy in FeRh/MgO bilayers,"Ultra-thin film of FeRh on insulator MgO substrate has been investigated
+usingab-initio electronic structure calculations. From this calculation, we
+have found the interesting effect of epitaxial strain on the magnetocrystalline
+anisotropy (MCA). Analysis of the energy and k-resolved distribution of the
+orbital character of the band structure reveals that MCA largely arises from
+the spin-orbit coupling (SOC) between dx2-y2 andd xz,yz orbitals of Fe atoms at
+the FeRh/MgO interface. We demonstrate that the strain has significant effects
+on the MCA: It not only affects the value of the MCA but also induces a
+switching of the magnetic easy axis from perpendicular to in-plane direction.
+The mechanism is the strain-induced shifts of the SOC d-states. Our work
+demonstrates that strain engineering can open a viable pathway towards
+tailoring magnetic properties for antiferromagetic spintronic applications.",1908.04761v1
+2019-08-06,Prediction magnetocrystalline anisotripy Fe-Rh thin films via machine leaning,"Least absolute shrinkage and selection operator (Lasso) was originally
+formulated for least squares models and this simple case reveals a substantial
+amount about the behavior of the estimator. It also shows that the coefficient
+estimates need not be unique if covariates are collinear. Using this Lasso
+technique, we analyze a magnetocrystalline anisotropy energy which is a
+long-standing issue in transition-metal thin films, expectially for Fe-Rh thin
+film systems on a MgO substrate. Our LASSO regression took advantage of the
+data obtained from first principles calculations for single slabs with seven
+atomic-layers of binary Fe-Rh films on MgO(001). In the case of Fe-Rh thin
+films, we have successfully found a linear behavior between the MCA energy and
+the anisotropy of orbital moments.",1908.04762v1
+2019-11-26,Mapping Skyrmion Stability in Uniaxial Lacunar Spinel Magnets from First-Principles,"The identification of general principles for stabilizing magnetic skyrmion
+phases in bulk materials over wide ranges of temperatures is a prerequisite to
+the development of skyrmion-based spintronic devices. Lacunar spinels with the
+formula GaM4X8 with M=V, Mo; X=S, Se are a convenient case study towards this
+goal as they are some of the first bulk systems suggested to host equilibrium
+chiral skyrmions far from the paramagnetic transition. We derive the magnetic
+phase diagrams likely to be observed in these materials, accounting for all
+possible magnetic interactions, and prove that skyrmion stability in the
+lacunar spinels is a general consequence of their crystal symmetry rather than
+the details of the material chemistry. Our results are consistent with all
+experimental reports in this space and demonstrate that the differences in the
+phase diagrams of particular spinel chemistries are determined by
+magnetocrystalline anisotropy, up to a normalization factor. We conclude that
+skyrmion formation over wide ranges of temperatures can be expected in all
+lacunar spinels, as well as in a wide range of uniaxial systems with low
+magnetocrystalline anisotropy.",1911.11297v2
+2020-12-09,Spin-lattice model for cubic crystals,"We present a methodology based on the N\'{e}el model to build a classical
+spin-lattice Hamiltonian for cubic crystals capable of describing magnetic
+properties induced by the spin-orbit coupling like magnetocrystalline
+anisotropy and anisotropic magnetostriction, as well as exchange
+magnetostriction. Taking advantage of the analytical solutions of the N\'{e}el
+model, we derive theoretical expressions for the parameterization of the
+exchange integrals and N\'{e}el dipole and quadrupole terms that link them to
+the magnetic properties of the material. This approach allows to build accurate
+spin-lattice models with the desire magnetoelastic properties. We also explore
+a possible way to model the volume dependence of magnetic moment based on the
+Landau energy. This new feature can allow to consider the effects of
+hydrostatic pressure on the saturation magnetization. We apply this method to
+develop a spin-lattice model for BCC Fe and FCC Ni, and we show that it
+accurately reproduces the experimental elastic tensor, magnetocrystalline
+anisotropy under pressure, anisotropic magnetostrictive coefficients, volume
+magnetostriction and saturation magnetization under pressure at
+zero-temperature. This work could constitute a step towards large-scale
+modeling of magnetoelastic phenomena.",2012.05076v3
+2021-09-24,Impact of local arrangement of Fe and Ni on the phase stability and magnetocrystalline anisotropy in Fe-Ni-Al Heusler alloys,"On the basis of density functional calculations, we report on a comprehensive
+study of the influences of atomic arrangement and Ni substitution for Al on the
+ground state structural and magnetic properties for Fe$_2$Ni$_{1+x}$Al$_{1-x}$
+Heusler alloys. We discuss systematically the competition between five
+Heusler-type structures formed by shuffles of Fe and Ni atoms and their
+thermodynamic stability. All~Ni-rich Fe$_2$Ni$_{1+x}$Al$_{1-x}$ tend to
+decompose into a dual-phase mixture consisting of Fe$_2$NiAl and~FeNi.
+The~successive replacement of Ni by Al leads to a change of ground state
+structure and eventually an increase in magnetocrystalline anisotropy
+energy~(MAE). We predict for stoichiometric Fe$_2$NiAl a ground state structure
+with nearly cubic lattice parameters but alternating layers of Fe and Ni
+possessing an uniaxial MAE which is even larger than tetragonal L1$_0$-FeNi.
+This opens an alternative route for improving the phase stability and magnetic
+properties in FeNi-based permanent magnets.",2109.12005v2
+2022-03-22,A strategic high throughput search for identifying stable Li based half Heusler alloys for spintronics applications,"In this work, high throughput DFT calculations are performed on the alkali
+metal-based half Heusler alloys; LiY$_p$Y$^\prime_{1-p}$S (Y, Y$^\prime$ = V,
+Cr, Mn, Fe, Co, Ni and $\mathit{p}$ = 0, 0.25, 0.5, 0.75, 1). Starting with 243
+structural replica, systematic filters are designed to select the energetically
+and vibrationally favorable compositions by considering the contributions
+stemming from the magnetic alignments of the ions. Thereby, 26 dynamically
+stable magnetic compositions are identified, of which 10 are found to be
+ferromagnetic (FM), 4 antiferromagnetic (AFM) and 12 ferrimagnetic (FiM). 4 FM
+and 8 FiM ones are found to show 100 $\%$ spin polarization. Further,
+tetragonal distortion is found to be present in 4 FM, 3 FiM and 4 AFM
+compositions, which indicates the possibility of easy-axis magnetocrystalline
+anisotropy. The ferromagnetic LiFe$_{0.5}$Mn$_{0.5}$S and antiferromagnetic
+LiFeS are found to have the most prominent easy-axis magnetocrystalline
+anisotropy.",2203.11794v1
+2022-09-18,Magnetocrystalline Anisotropy and Magnetocaloric Effect Studies on the Room-temperature 2D Ferromagnetic Cr$_4$Te$_5$,"We present a thorough study on the magnetoanisotropic properties and
+magnetocaloric effect in the layered ferromagnetic Cr$_4$Te$_5$ single crystals
+by performing the critical behaviour analysis of magnetization isotherms. The
+critical exponents $\beta$=0.485(3), $\gamma$=1.202(5), and $\delta$=3.52(3)
+with a Curie temperature of $T_C \approx 340.73(4)$ K are determined by the
+modified Arrott plots. We observe a large magnetocrystalline anisotropy
+K$_u$=330 kJ/$m^3$ at 3 K which gradually decreases with increasing
+temperature. Maximum entropy change -$\Delta S_{M}^{max}$ and the relative
+cooling power (RCP) are found to be 2.77 $J/kg-K$ and 88.29 $J/kg$,
+respectively near $T_C$ when the magnetic field applied parallel to
+$\it{ab}$-plane. Rescaled -$\Delta S_M (T, H)$ data measured at various
+temperatures and fields collapse into a single universal curve, confirming the
+second order magnetic transition in this system. Following the renormalization
+group theory analysis, we find that the spin-coupling is of 3D Heisenberg-type,
+$\{d:n\}=\{3:3\}$, with long-range exchange interactions decaying as $J (r) =
+r^{-(d+\sigma)}= r^{-4.71}$.",2209.08477v1
+2023-06-09,Finite-temperature second-order perturbation analysis of magnetocrystalline anisotropy energy of L10-type ordered alloys,"We present a novel finite-temperature second-order perturbation method
+incorporating spin-orbit coupling to investigate the temperature-dependent
+site-resolved contributions to the magnetocrystalline anisotropy energy (MAE),
+specifically K1(T), in FePt, MnAl, and FeNi alloys. Our developed method
+successfully reproduces the results obtained using the force theorem from our
+previous work. By employing this method, we identify the key sites responsible
+for the distinctive behaviors of MAE in these alloys, shedding light on the
+inadequacy of the spin model in capturing the temperature dependence of MAE in
+itinerant magnets. Moreover, we explore the lattice expansion effect on the
+temperature dependence of on-site contributions to K1(T) in FeNi. Our results
+not only provide insights into the limitations of the spin model in explaining
+the temperature dependence of MAE in itinerant ferromagnets but also highlight
+the need for further investigations. These findings contribute to a deeper
+understanding of the complex nature of MAE in itinerant magnetic systems.",2306.05681v1
+2023-09-12,Predicting synthesizable manganese nitride with unprecedentedly giant magnetocrystalline anisotropy energy,"Using modern crystal structure prediction program (CALYPSO), we searched many
+experimentally synthesizable low-energy structures with perfect or nearly
+perfect easy-axis magnetocrystalline anisotropy energy (MAE) in manganese
+nitride, including MnN, Mn2N, Mn3N2, Mn5N2, Mn4N, respectively, which are the
+more frequently studied stoichiometries by experimental researchers. MnN (
+I-42d) shows giant MAE with values of E001=1006, E010=0, E100=920 ueV/atom
+(same hereinafter), respectively. One perfect easy-axis MAE in Mn3N2 (P42/mmc)
+with correspondent values of E010=E100=12 is observed, the other nearly perfect
+easy-axis MAE one (Ibam) with respective values of E001=324 and E010=345 is
+observed. Four almost totally perfect easy-axis MAE structures are obtained in
+Mn2N, including P4/mmm with individual E001=249 and E100=250, Pccm with
+E001=E100=62, P4/nmm with E001=58 and E100=60, Imma with E001=108 and E100=109,
+respectively. Three structures including one perfect candidates are found in
+Mn4N, including Fmmm with individual E001=126 and E010=121, I4/mmm with
+E010=127 and E100=133, I4/mmm with E001= E100=169, respectively. Too many
+valuable structures are deserved to be further studied by both theoretical and
+experimental scientists. The present study might attract close attention to
+these several compounds.",2309.06110v1
+2023-09-16,Investigation of the Anomalous and Topological Hall Effects in Layered Monoclinic Ferromagnet Cr$_{2.76}$Te$_4$,"We studied the electrical transport, Hall effect, and magnetic properties of
+monoclinic layered ferromagnet Cr$_{2.76}$Te$_4$. Our studies demonstrate
+Cr$_{2.76}$Te$_4$ to be a soft ferromagnet with strong magnetocrystalline
+anisotropy. Below 50 K, the system shows an antiferromagnetic-like transition.
+Interestingly, between 50 and 150 K, we observe fluctuating magnetic moments
+between in-plane and out-of-plane orientations, leading to non-coplanar spin
+structure. On the other hand, the electrical resistivity data suggest it to be
+metallic throughout the measured temperature range, except a $kink$ at around
+50 K due to AFM ordering. The Rhodes-Wohlfarth ratio
+$\frac{\mu_{eff}}{\mu_{s}}=1.89 (>1)$ calculated from our magnetic studies
+confirms that Cr$_{2.76}$Te$_4$ is an itinerant ferromagnet. Large anomalous
+Hall effect has been observed due to the skew-scattering of impurities and the
+topological Hall effect has been observed due to non-coplanar spin-structure in
+the presence of strong magnetocrystalline anisotropy. We examined the mechanism
+of anomalous Hall effect by employing the first principles calculations.",2309.08898v1
+2024-03-21,Magnetocrystalline anisotropy in metallic systems: fast and stable estimation in Green`s functions formalism,"In this work we suggest a theoretical approach, that allows to study the
+effects of magnetocrystalline anisotropy (MCA) in metallic systems using the
+Green`s functions formalism. We demonstrate that employment of the reciprocal
+space resolution instead of its reduction in the inter-site variant essentially
+improves the numerical stability of MCA energy by means of Monkhorst-Pack grid
+density and spatial convergence. The latter problem is able to be completely
+removed due to rigorous analytical replacement of pairwise atomic summation by
+simple composition of sublattices contributions, calculated as a whole. The
+approach is validated on the effective model of single atom, which nevertheless
+inherits the qualitative MCA picture of Co monolayer and Au/Co/Au sandwiched
+material. The numerical convergence is confirmed using the model of atomic
+chain in the strong metallic regime. For cobalt monoxide, described by ab
+initio calculations using GGA+U, the MCA energy angular profile reveals the
+prevailing role of ferromagnetically aligned Co sublattices in forming of the
+easy axis.",2403.14241v1
+2003-11-14,Large anisotropy in the paramagnetic susceptibility of SrRuO3 films,"By using the extraordinary Hall effect in SrRuO3 films we performed sensitive
+measurements of the paramagnetic susceptibility in this itinerant ferromagnet,
+from Tc (~ 150 K) to 300 K. These measurements, combined with measurements of
+magnetoresistance, reveal that the susceptibility, which is almost isotropic at
+300 K, becomes highly anisotropic as the temperature is lowered, diverging
+along a single crystallographic direction in the vicinity of Tc. The results
+provide a striking manifestation of the effect of exceptionally large
+magnetocrystalline anisotropy in the paramagnetic state of a 4d itinerant
+ferromagnet.",0311341v1
+2011-08-12,Magnetic anisotropy of FePt: effect of lattice distortion and chemical disorder,"We perform first principles calculations of the magnetocrystalline anisotropy
+energy in the five L10 FePt samples studied experimentally by Ding et al. [J.
+App. Phys. 97, 10H303 (2005)]. The effect of temperature-induced spin
+fluctuations is estimated by scaling the MAE down according to previous
+Langevin dynamics simulations. Including chemical disorder as given in
+experiment, the experimental correlation between MAE and lattice mismatch is
+qualitatively well reproduced. Moreover we determine the chemical order
+parameters that reproduce exactly the experimental MAE of each sample. We
+conclude that the MAE is determined by the chemical disorder rather than by
+lattice distortion.",1108.2572v1
+2013-01-17,Imaging the antiferromagnetic to ferromagnetic first order phase transition of FeRh,"The antiferromagnetic (AFM) to ferromagnetic (FM) first order phase
+transition of an epitaxial FeRh thin-film has been studied with x-ray magnetic
+circular dichroism using photoemission electron microscopy. The FM phase is
+magnetized in-plane due to shape anisotropy, but the magnetocrystalline
+anisotropy is negligible and there is no preferred in-plane magnetization
+direction. When heating through the AFM to FM phase transition the nucleation
+of the FM phase occurs at many independent nucleation sites with random domain
+orientation. The domains subsequently align to form the final FM domain
+structure. We observe no pinning of the FM domain structure.",1301.4164v1
+2013-04-19,First Principles Calculation of Magnetocrystalline Anisotropy Energy of MnBi and MnB_{1-x}Sn_x,"We calculated the magnetic anisotropy constant Ku of MnBi using a first
+principles approach, and obtained a negative Ku in agreeable with experimental
+results. Furthermore, we also found a band filling dependence indicating that a
+slight decrease in the valence electron number will change Ku from negative to
+positive. When some of the Bi is replaced with Sn to decrease the valence
+electron number, the Ku value of MnBi1-xSnx drastically changes to a positive
+value, Ku~2 MJ/m3, for x > 0.05.",1304.5307v1
+2013-07-10,Magnetocrystalline Anisotropy and the Magnetocaloric Effect in Fe2P,"Magnetic and magnetocaloric properties of high-purity, giant magnetocaloric
+polycrystalline and single-crystalline Fe2P are investigated. Fe2P displays a
+moderate magnetic entropy change which spans over 70 K and the presence of
+strong magnetization anisotropy proves this system is not fully itinerant but
+displays a mix of itinerant and localized magnetism. The properties of pure
+Fe2P are compared to those of giant magnetocaloric (Fe,Mn)2(P,A) compounds
+helping understand the exceptional characteristics shown by the latter which
+are so promising for heat pump and energy conversion applications.",1307.2784v1
+2014-05-22,Improvement of magnetic hardness at finite temperatures: ab initio disordered local moment approach for YCo$_5$,"Temperature dependence of the magnetocrystalline anisotropy energy and
+magnetization of the prototypical rare-earth magnet YCo$_5$ is calculated from
+first principles, utilizing the relativistic disordered local moment approach.
+We discuss a strategy to enhance the finite-temperature anisotropy field by
+hole doping, paving the way for an improvement of the coercivity near room
+temperature or higher.",1405.5673v2
+2007-05-20,Anisotropy and magnetization reversal with chains of submicron-sized Co hollow spheres,"Magnetic properties with chains of hcp Co hollow spheres have been studied.
+The diameter of the spheres ranges from 500 to 800 nm, with a typical shell
+thickness of about 60 nm. The shell is polycrystalline with an average
+crystallite size of 20 to 35 nm. The blocking temperature determined by the
+zero-field-cooling MZFC(T) measurement at H = 90 Oe is about 325 K. The
+corresponding effective anisotropy is determined as, Keff = 4.6*10^4 J/m^3. In
+addition, the blocking temperature and the effective anisotropy determined by
+the analysis on HC(T) are 395 K and 5.7*10^4 J/m^3, respectively. The
+experimentally determined anisotropy is smaller by one order of magnitude than
+the magnetocrystalline anisotropy of the bulk hcp Co, which is about 3 to
+5*10^5 J/m^3. A further analysis on HC(T) shows that the magnetization reversal
+follows a nucleation rotational mode with an effective switching volume, V* =
+2.3*10^3 nm^3. The corresponding effective diameter is calculated as 16.4 nm.
+It is slightly larger than the coherence length of Co, about 15 nm. The
+possible reason for the much reduced magnetic anisotropy is discussed briefly.",0705.2870v1
+2010-09-04,Uniaxial contribution to the magnetic anisotropy of La0.67Sr0.33MnO3 thin films induced by orthorhombic crystal structure,"La0.67Sr0.33MnO3 (LSMO) thin films under compressive strain have an
+orthorhombic symmetry with (1-10)o and (001)o in-plane orientations. (The
+subscript o denotes the orthorhombic symmetry.) Here, we grew LSMO on cubic
+(LaAlO3)0.3-(Sr2AlTaO6)0.7 (LSAT) substrates and observed a uniaxial
+contribution to the magnetic anisotropy which is related to the orthorhombic
+crystal structure. Since the lattice mismatch is equal in the two directions,
+the general understanding of anisotropy in LSMO, which relates the uniaxial
+anisotropy to differences in strain, cannot explain the results. These findings
+suggest that the oxygen octahedra rotations associated with the orthorhombic
+structure, possibly resulting in different Mn-O-Mn bond angles and therefore a
+change in magnetic coupling between the [1-10]o and [001]o directions,
+determine the anisotropy. We expect these findings to lead to a better
+understanding of the microscopic origin of the magnetocrystalline anisotropy in
+LSMO.",1009.0815v1
+2017-02-17,Magnetic anisotropy in Permalloy: hidden quantum mechanical features,"By means of relativistic, first principles calculations, we investigate the
+microscopic origin of the vanishingly low magnetic anisotropy of Permalloy,
+here proposed to be intrinsically related to the local symmetries of the alloy.
+It is shown that the local magnetic anisotropy of individual atoms in Permalloy
+can be several orders of magnitude larger than that of the bulk sample, and
+5-10 times larger than that of elemental Fe or Ni. We, furthermore, show that
+locally there are several easy axis directions that are favored, depending on
+local composition. The results are discussed in the context of perturbation
+theory, applying the relation between magnetic anisotropy and orbital moment.
+Permalloy keeps its strong ferromagnetic nature due to the exchange energy to
+be larger than the magnetocrystalline anisotropy. Our results shine light on
+the magnetic anisotropy of permalloy and of magnetic materials in general, and
+in addition enhance the understanding of pump-probe measurements and ultrafast
+magnetization dynamics.",1702.05414v1
+2018-10-12,Room temperature biaxial magnetic anisotropy in La0.67Sr0.33MnO3 thin films on SrTiO3 buffered MgO (001) substrates for spintronic applications,"Spintronics exploits the magnetoresistance effects to store or sense the
+magnetic information. Since the magnetoresistance strictly depends on the
+magnetic anisotropy of the system, it is fundamental to set a defined
+anisotropy to the system. Here, we investigate by means of vectorial
+Magneto-Optical Kerr Magnetometry (v-MOKE), half-metallic La0.67Sr0.33MnO3
+(LSMO) thin films that exhibit at room temperature pure biaxial magnetic
+anisotropy if grown onto MgO (001) substrate with a thin SrTiO3 (STO) buffer.
+In this way, we can avoid unwanted uniaxial magnetic anisotropy contributions
+that may be detrimental for specific applications. The detailed study of the
+angular evolution of the magnetization reversal pathways, critical fields
+(coercivity and switching) allows for disclosing the origin of the magnetic
+anisotropy, which is magnetocrystalline in nature and shows four-fold symmetry
+at any temperature.",1810.05435v1
+2019-08-30,"Magnetization reversal, damping properties and magnetic anisotropy of L10-ordered FeNi thin films","L10 ordered magnetic alloys such as FePt, FePd, CoPt and FeNi are well known
+for their large magnetocrystalline anisotropy. Among these, L10-FeNi alloy is
+economically viable material for magnetic recording media because it does not
+contain rare earth and noble elements. In this work, L10-FeNi films with three
+different strengths of anisotropy were fabricated by varying the deposition
+process in molecular beam epitaxy system. We have investigated the
+magnetization reversal along with domain imaging via magneto optic Kerr effect
+based microscope. It is found that in all three samples, the magnetization
+reversal is happening via domain wall motion. Further ferromagnetic resonance
+(FMR) spectroscopy was performed to evaluate the damping constant and magnetic
+anisotropy. It was observed that the FeNi sample with moderate strength of
+anisotropy exhibits low value of damping constant ~ 4.9X10^-3. In addition to
+this, it was found that the films possess a mixture of cubic and uniaxial
+anisotropies.",1908.11761v1
+2009-11-20,Magnetisation dynamics in exchange coupled spring systems with perpendicular anisotropy,"Magnetisation dynamics in exchange spring magnets have been studied using
+simulations of the FePt/Fe bilayer system. The FePt hard layer exhibits strong
+perpendicular magnetocrystalline anisotropy, while the soft (Fe) layer has
+negligible magnetocrystalline anisotropy. The variation of the local spin
+orientation in the Fe layer is determined by the competition of the exchange
+coupling interaction with the hard layer and the magnetostatic energy which
+favours in-plane magnetisation. Dynamics were studied by monitoring the
+response of the Fe layer magnetisation after the abrupt application of a
+magnetic field which causes the systems to realign via precessional motion.
+This precessional motion allows us to obtain the frequency spectrum and hence
+examine the dynamical magnetisation motion. Since the rotation of the spins in
+the soft layer does not have a well defined magnetic anisotropy, the system
+does not present the usual frequency field characteristics for a thin film.
+Additionally we obtain multi-peaked resonance spectra for the application of
+magnetic fields perpendicular to the film plane, though we discount the
+existence of spin wave modes and propose that this arises due to variations in
+the local effective field across the Fe layer. The dynamic response is only
+considered in the Fe layer, with the FePt layer held fixed in the perpendicular
+orientation.",0911.4137v2
+2012-08-21,High temperature structural and magnetic properties of cobalt nanowires,"We present in this paper the structural and magnetic properties of high
+aspect ratio Co nanoparticles (~10) at high temperatures (up to 623 K) using in
+situ X ray diffraction (XRD) and SQUID characterizations. We show that the
+anisotropic shapes, the structural and texture properties are preserved up to
+500 K. The coercivity can be modelled by u0Hc=2(Kmc+Kshape)/Ms with Kmc the
+magnetocrystalline anisotropy constant, Kshape the shape anisotropy constant
+and Ms the saturation magnetization. Hc decreases linearly when the temperature
+is increased due to the loss of the Co magnetocrystalline anisotropy
+contribution. At 500K, 50% of the room temperature coercivity is preserved
+corresponding to the shape anisotropy contribution only. We show that the
+coercivity drop is reversible in the range 300 - 500 K in good agreement with
+the absence of particle alteration. Above 525 K, the magnetic properties are
+irreversibly altered either by sintering or by oxidation.",1208.4403v2
+2014-07-06,Control of single-spin magnetic anisotropy by exchange coupling,"The properties of quantum systems interacting with their environment,
+commonly called open quantum systems, can be strongly affected by this
+interaction. While this can lead to unwanted consequences, such as causing
+decoherence in qubits used for quantum computation, it can also be exploited as
+a probe of the environment. For example, magnetic resonance imaging is based on
+the dependence of the spin relaxation times of protons in water molecules in a
+host's tissue. Here we show that the excitation energy of a single spin, which
+is determined by magnetocrystalline anisotropy and controls its stability and
+suitability for use in magnetic data storage devices, can be modified by
+varying the exchange coupling of the spin to a nearby conductive electrode.
+Using scanning tunnelling microscopy and spectroscopy, we observe variations up
+to a factor of two of the spin excitation energies of individual atoms as the
+strength of the spin's coupling to the surrounding electronic bath changes.
+These observations, combined with calculations, show that exchange coupling can
+strongly modify the magnetic anisotropy. This system is thus one of the few
+open quantum systems in which the energy levels, and not just the excited-state
+lifetimes, can be controllably renormalized. Furthermore, we demonstrate that
+the magnetocrystalline anisotropy, a property normally determined by the local
+structure around a spin, can be electronically tuned. These effects may play a
+significant role in the development of spintronic devices5 in which an
+individual magnetic atom or molecule is coupled to conducting leads.",1407.1542v1
+2018-09-04,Enhanced perpendicular magnetocrystalline anisotropy energy in an artificial magnetic material with bulk spin-momentum coupling,"We systematically investigate the perpendicular magnetocrystalline anisotropy
+(MCA) in Co$-$Pt/Pd-based multilayers. Our magnetic measurement data shows that
+the asymmetric Co/Pd/Pt multilayer has a significantly larger perpendicular
+magnetic anisotropy (PMA) energy compared to the symmetric Co/Pt and Co/Pd
+multilayer samples. We further support this experiment by first principles
+calculations on the CoPt$_2$, CoPd$_2$, and CoPtPd, which are composite bulk
+materials that consist of three atomic layers in a unit cell, Pt/Co/Pt,
+Pd/Co/Pd, Pt/Co/Pd, respectively. By estimating the contribution of bulk
+spin-momentum coupling to the MCA energy, we show that the CoPtPd multilayer
+with the symmetry breaking has a significantly larger perpendicular magnetic
+anisotropy (PMA) energy than the other multilayers that are otherwise similar
+but lack the symmetry breaking. This observation thus provides an evidence of
+the PMA enhancement due to the structural inversion symmetry breaking and
+highlights the asymmetric CoPtPd as the first artificial magnetic material with
+bulk spin-momentum coupling, which opens a new pathway toward the design of
+materials with strong PMA.",1809.00801v3
+2022-09-09,Understanding magnetocrystalline anisotropy based on orbital and quadrupole moments,"Understanding magnetocrystalline anisotropy (MCA) is fundamentally important
+for developing novel magnetic materials. Therefore, clarifying the relationship
+between MCA and local physical quantities observed by spectroscopic
+measurements, such as the orbital and quadrupole moments, is necessary. In this
+review, we discuss MCA and the distortion effects in magnetic materials with
+transition metals (TMs) based on the orbital and quadrupole moments, which are
+related to the spin-conserving and spin-flip terms in the second-order
+perturbation calculations, respectively. We revealed that orbital moment
+stabilized the spin moment in the direction of the larger orbital moment, while
+the quadrupole moment stabilized the spin moment along the longitudinal
+direction of the spin-density distribution. The MCA of the magnetic materials
+with TMs and their interfaces can be determined from the competition between
+these two contributions. We showed that the perpendicular MCA of the
+face-centered cubic (fcc) Ni with tensile tetragonal distortion arose from the
+orbital moment anisotropy, whereas that of Mn-Ga alloys originated from the
+quadrupole moment of spin density. In contrast, in the Co/Pd(111) multilayer
+and Fe/MgO(001), both the orbital moment anisotropy and quadrupole moment of
+spin density at the interfaces contributed to the perpendicular MCA.
+Understanding the MCA of magnetic materials and interfaces based on orbital and
+quadrupole moments is essential to design MCA of novel magnetic applications.",2209.04070v1
+2023-07-28,Revisiting Néel 60 years on: the magnetic anisotropy of $\mathrm{L}1_0$ FeNi (tetrataenite),"The magnetocrystalline anisotropy energy of atomically ordered
+$\mathrm{L}1_0$ FeNi (the meteoritic mineral tetrataenite) is studied within a
+first-principles electronic structure framework. Two compositions are examined:
+equiatomic Fe$_{0.5}$Ni$_{0.5}$ and an Fe-rich composition,
+Fe$_{0.56}$Ni$_{0.44}$. It is confirmed that, for the single crystals modelled
+in this work, the leading-order anisotropy coefficient $K_1$ dominates the
+higher-order coefficients $K_2$ and $K_3$. To enable comparison with
+experiment, the effects of both imperfect atomic long-range order and finite
+temperature are included. While our computational results initially appear to
+undershoot the measured experimental values for this system, careful scrutiny
+of the original analysis due to N\'{e}el et al. [J. Appl. Phys. 35, 873 (1964)]
+suggests that our computed value of $K_1$ is, in fact, consistent with
+experimental values, and that the noted discrepancy has its origins in the
+nanoscale polycrystalline, multivariant nature of experimental samples, that
+yields much larger values of $K_2$ and $K_3$ than expected a priori. These
+results provide fresh insight into the existing discrepancies in the literature
+regarding the value of tetrataenite's uniaxial magnetocrystalline anisotropy in
+both natural and synthetic samples.",2307.15470v2
+2009-10-22,Interplay between the magnetic anisotropy contributions of Cobalt nanowires,"We report on the magnetic properties and the crystallographic structure of
+the cobalt nanowire arrays as a function of their nanoscale dimensions. X-ray
+diffraction measurements show the appearance of an in-plane HCP-Co phase for
+nanowires with 50 nm diameter, suggesting a partial reorientation of the
+magnetocrystalline anisotropy axis along the membrane plane with increasing
+pore diameter. No significant changes in the magnetic behavior of the nanowire
+system are observed with decreasing temperature, indicating that the effective
+magnetoelastic anisotropy does not play a dominant role in the remagnetization
+processes of individual nanowires. An enhancement of the total magnetic
+anisotropy is found at room temperature with a decreasing nanowire
+diameter-to-length ratio (d/L), a result that is quantitatively analyzed on the
+basis of a simplified shape anisotropy model.",0910.4285v1
+2010-09-08,Controllable modification of the anisotropy energy in Laves phase YFe2 by Ar+ ion implantation,"Implanted 3.25 keV Ar+ ions have been used to modify the in-plane bulk
+anisotropy in thin films of epitaxially grown Laves phase YFe2. The magneto
+optical Kerr effect, vibrating sample magnetometry and computational modeling
+have been used to show that the dominant source of anisotropy changes from
+magnetoelastic in as-grown samples to magnetocrystalline in ion implanted
+samples. This change occurs at a critical fluence of order 1017 Ar+ ions cm-2.
+The change in source of the anisotropy is attributed to a relaxation of the
+strain inherent in the epitaxially grown thin-films. Atomic force microscopy
+shows that the samples' topography remains unchanged after ion implantation.
+The ability to control the dominant source of magnetic anisotropy without
+affecting the sample surface could have important consequences in the
+fabrication of patterned media for high use in density magnetic data storage
+devices.",1009.1520v1
+2014-11-10,Temperature evolution of the effective magnetic anisotropy in the MnCr$_2$O$_4$ spinel,"In this work we present a study of the low temperature magnetic phases of
+polycrystalline MnCr$_2$O$_4$ spinel through dc magnetization and ferromagnetic
+resonance spectroscopy (FMR). Through these experiments we determined the main
+characteristic temperatures: T$_C$ $\sim$41 K and T$_H$ $\sim$18 K
+corresponding, respectively, to the ferrimagnetic order and to the low
+temperature helicoidal transitions. The temperature evolution of the system is
+described by a phenomenological approach that considers the different terms
+that contribute to the free energy density. Below the Curie temperature the FMR
+spectra were modeled by a cubic magnetocrystalline anisotropy to the second
+order, with $K_1$ and $K_2$ anisotropy constants that define the easy
+magnetization axis along the <110> direction. At lower temperatures, the
+formation of a helicoidal phase was considered by including uniaxial anisotropy
+axis along the [1-10] propagation direction of the spiral arrange, with a $K_u$
+anisotropy constant. The values obtained from the fittings at 5 K are
+$K_1$=-2.3x10$^4$ erg/cm$^3$, $K^2$=6.4x10$^4$ erg/cm$^3$ and $K_u$=7.5x10$^4$
+erg/cm$^3$.",1411.2461v1
+2014-12-23,Tuning the magnetic anisotropy of single molecules,"The magnetism of single atoms and molecules is governed by the atomic scale
+environment. In general, the reduced symmetry of the surrounding splits the $d$
+states and aligns the magnetic moment along certain favorable directions. Here,
+we show that we can reversibly modify the magnetocrystalline anisotropy by
+manipulating the environment of single iron(II) porphyrin molecules adsorbed on
+Pb(111) with the tip of a scanning tunneling microscope. When we decrease the
+tip--molecule distance, we first observe a small increase followed by an
+exponential decrease of the axial anisotropy on the molecules. This is in
+contrast to the monotonous increase observed earlier for the same molecule with
+an additional axial Cl ligand. We ascribe the changes in the anisotropy of both
+species to a deformation of the molecules in the presence of the attractive
+force of the tip, which leads to a change in the $d$ level alignment. These
+experiments demonstrate the feasibility of a precise tuning of the magnetic
+anisotropy of an individual molecule by mechanical control.",1412.7454v2
+2015-11-24,Ferromagnetic Resonance of a YIG film in the Low Frequency Regime,"An improved method for characterizing the magnetic anisotropy of films with
+cubic symmetry is described and is applied to an yttrium iron garnet (111)
+film. Analysis of the FMR spectra performed both in-plane and out-of-plane from
+0.7 to 8 GHz yielded the magnetic anisotropy constants as well as the
+saturation magnetization. The field at which FMR is observed turns out to be
+quite sensitive to anisotropy constants (by more than a factor ten) in the low
+frequency (< 2 GHz) regime and when the orientation of the magnetic field is
+nearly normal to the sample plane; the restoring force on the magnetization
+arising from the magnetocrystalline anisotropy fields is then comparable to
+that from the external field, thereby allowing the anisotropy constants to be
+determined with greater accuracy. In this region, unusual dynamical behaviors
+are observed such as multiple resonances and a switching of FMR resonance with
+only a 1 degree change in field orientation at 0.7 GHz.",1511.07892v1
+2016-10-10,Origin of magnetic anisotropy in doped Ce$_2$Co$_{17}$ alloys,"Magnetocrystalline anisotropy (MCA) in doped Ce$_{2}$Co$_{17}$ and other
+competing structures was investigated using density functional theory. We
+confirmed that the MCA contribution from dumbbell Co sites is very negative.
+Replacing Co dumbbell atoms with a pair of Fe or Mn atoms greatly enhance the
+uniaxial anisotropy, which agrees quantitatively with experiment, and this
+enhancement arises from electronic-structure features near the Fermi level,
+mostly associated with dumbbell sites. With Co dumbbell atoms replaced by other
+elements, the variation of anisotropy is generally a collective effect and
+contributions from other sublattices may change significantly. Moreover, we
+found that Zr doping promotes the formation of 1-5 structure that exhibits a
+large uniaxial anisotropy, such that Zr is the most effective element to
+enhance MCA in this system.",1610.02767v2
+2018-07-18,Controlled anisotropic dynamics of tightly bound skyrmions in a synthetic ferrimagnet due to skyrmion-deformation mediated by induced uniaxial in-plane anisotropy,"We study speed and skew deflection-angle dependence on skyrmion deformations
+of a tightly bound two-skyrmion state in a synthetic ferrimagnet. We condsider
+here, an in-plane uniaxial magnetocrystalline anisotropy-term in order to
+induce lateral shape distortions and an overall size modulation of the
+skyrmions due to a reduction of the effective out-of-plane anisotropy, thus
+affecting the skyrmion speed, skew-deflection and inducing anisotropy in these
+quantities with respect to the driving current-angle. Because of frustrated
+dipolar interactions in a synthetic ferrimagnet, sizeable skyrmion deformations
+can be induced with relatively small induced anisotropy constants and thus a
+wide range of tuneability can be achieved. We also show analytically, that a
+consequence of the skyrmion deformation can, under certain conditions cause a
+skyrmion deflection with respect to driving-current angles, unrelated to the
+topological charge. Results are analyzed by a combination of micromagnetic
+simulations and a compound particle description within the Thiele-formalism
+from which an over-all mobility tensor is constructed. This work offers an
+additional path towards in-situ tuning of skyrmion dynamics.",1807.06884v2
+2018-07-24,Impact of magnetic moment and anisotropy of Co$_\textrm{1-x}$Fe$_\textrm{x}$ thin films on the magnetic proximity effect of Pt,"We present a systematic study of the magnetic proximity effect in Pt,
+depending on the magnetic moment and anisotropy of adjacent metallic
+ferromagnets. Element-selective x-ray resonant magnetic reflectivity
+measurements at the Pt absorption edge (11565$\,$eV) are carried out to
+investigate the spin polarization of Pt in Pt/Co$_\textrm{1-x}$Fe$_\textrm{x}$
+bilayers. We observe the largest magnetic moment of (0.72$\,\pm\,$0.03)$\,
+\mu_\textrm{B}$ per spin polarized Pt atom in
+Pt/Co$_\textrm{33}$Fe$_\textrm{67}$, following the Slater-Pauling curve of
+magnetic moments in Co-Fe alloys. In general, a clear linear dependence is
+observed between the Pt moment and the moment of the adjacent ferromagnet.
+Further, we study the magnetic anisotropy of the magnetized Pt which clearly
+adopts the magnetic anisotropy of the ferromagnet below. This is depicted for
+Pt on Fe(001) and on Co$_\textrm{50}$Fe$_\textrm{50}$(001), which have a
+45$^{\circ}$ relative rotation of the fourfold magnetocrystalline anisotropy.",1807.09032v2
+2004-07-14,An ab-initio theoretical investigation of the soft-magnetic properties of permalloys,"We study Ni80Fe20-based permalloys with the relativistic spin-polarized
+Korringa-Kohn-Rostoker electronic structure method. Treating the compositional
+disorder with the coherent potential approximation, we investigate how the
+magnetocrystalline anisotropy, K, and magnetostriction, lambda, of Ni-rich
+Ni-Fe alloys vary with the addition of small amounts of non-magnetic transition
+metals, Cu and Mo. From our calculations we follow the trends in K and lambda
+and find the compositions of Ni-Fe-Cu and Ni-Fe-Mo where both are near zero.
+These high permeability compositions of Ni-Fe-Cu and Ni-Fe-Mo match well with
+those discovered experimentally. We monitor the connection of the magnetic
+anisotropy with the number of minority spin electrons, Nmin. By raising Nmin
+via artificially increasing the band-filling of Ni80Fe20, we are able to
+reproduce the key features that underpin the magnetic softening we find in the
+ternary alloys. The effect of band-filling on the dependence of
+magnetocrystalline anisotropy on atomic short-range order in Ni80Fe20 is also
+studied. Our calculations, based on a static concentration wave theory,
+indicate that the susceptibility of the high permeability of the Ni-Fe-Cu and
+Ni-Fe-Mo alloys to their annealing conditions is also strongly dependent on the
+alloys' compositions. An ideal soft magnet appears from these calculations.",0407355v1
+2013-12-30,"Ground state search, hysteretic behaviour, and reversal mechanism of skyrmionic textures in confined helimagnetic nanostructures","Magnetic skyrmions have the potential to provide solutions for low-power,
+high-density data storage and processing. One of the major challenges in
+developing skyrmion-based devices is the skyrmions' magnetic stability in
+confined helimagnetic nanostructures. Through a systematic study of equilibrium
+states, using a full three-dimensional micromagnetic model including
+demagnetisation effects, we demonstrate that skyrmionic textures are the lowest
+energy states in helimagnetic thin film nanostructures at zero external
+magnetic field and in absence of magnetocrystalline anisotropy. We also report
+the regions of metastability for non-ground state equilibrium configurations.
+We show that bistable skyrmionic textures undergo hysteretic behaviour between
+two energetically equivalent skyrmionic states with different core orientation,
+even in absence of both magnetocrystalline and demagnetisation-based shape
+anisotropies, suggesting the existence of Dzyaloshinskii-Moriya-based shape
+anisotropy. Finally, we show that the skyrmionic texture core reversal dynamics
+is facilitated by the Bloch point occurrence and propagation.",1312.7665v3
+2014-03-17,Second-order Perturbation Formula for Magnetocrystalline Anisotropy using Orbital Angular Momentum Matrix,"We derive a second-order perturbation formula for an electronic system
+subject to spin-orbit interactions (SOI). The energy correction originates in
+the spin-conserving and the spin-flip transitions. The former are represented
+by the orbital angular momentum (OAM) acquired via the SOI. The latter come
+from the quantum fluctuation effect. By using our formula, we examine the
+relativistic electronic structures of a d orbital chain and L1_0 alloys. The
+appearance of OAM in the chain is understood by using a parabolic-bands model
+and the exact expressions of the single-particle states. The total energy is
+found to be accurately reproduced by the formula. The self-consistent fully
+relativistic first-principles calculations based on the density functional
+theory are performed for five L1_0 alloys. It is found that the formula
+reproduces qualitatively the behavior of their exact magnetocrystalline
+anisotropy (MCA) energies. While the MCA of FePt, CoPt, and FePd originates in
+the spin-conserving transitions, that in MnAl and MnGa originates in the
+spin-flip contributions. For FePt, CoPt, and FePd, the tendency of the MCA
+energy with the variation in the lattice constant obeys basically that of the
+spin-flip contributions. These results indicate that not only the anisotropy of
+OAM, but also that of spin-flip contributions must be taken into account for
+the understanding of the MCA of the L1_0 alloys.",1403.3987v1
+2016-11-22,Uranium ferromagnet with negligible magnetocrystalline anisotropy - $\mathrm{U_{4}Ru_{7}Ge_{6}}$,"Strong magnetocrystalline anisotropy is a well-known property of uranium
+compounds. The almost isotropic ferromagnetism in $\mathrm{U_{4}Ru_{7}Ge_{6}}$
+reported in this paper represents a striking exception. We present results of
+magnetization, AC susceptibility, thermal expansion, specific heat and
+electrical resistivity measurements performed on a $\mathrm{U_{4}Ru_{7}Ge_{6}}$
+single crystal at various temperatures and magnetic fields and discuss them in
+conjunction with results of first-principles electronic-structure calculations.
+$\mathrm{U_{4}Ru_{7}Ge_{6}}$ behaves as an itinerant 5$f$-electron ferromagnet
+($T_{\mathrm{C}}= 10.7 K$, $\mu_{\mathrm{S}}= 0.85 \mu_{\mathrm{B}}/f.u.$ at
+1.9 K. The ground-state easy-magnetization direction is along the [111] axis of
+the cubic lattice. The anisotropy field $\mu_{0}H_{\mathrm{a}}$ along the [001]
+direction is only of $\sim0.3 T$, which is at least 3 orders of magnitude
+smaller value than in other U ferromagnets. At $T_{r}=5.9 K$ the easy
+magnetization direction changes for [001] which holds at temperatures up to
+$T_{\mathrm{C}}$. The magnetoelastic interaction induces a rhombohedral
+(tetragonal) distortion of the paramagnetic cubic crystal lattice in case of
+the [111]([001]) easy-magnetization direction. The rhombohedral distortion is
+connected with two crystallographically inequivalent U sites. The ab initio
+calculated ground-state magnetic moment of $1.01 \mu_{\mathrm{B}}/f.u.$ is
+oriented along [111]. The two crystallographically inequivalent U sites are a
+consequence of spin-orbit coupling of the U 5$f$-electrons. In the excited
+state which is only 0.9 meV above the ground state the moment points to the
+[001] direction in agreement with experiment.",1611.07335v1
+2016-12-20,Magnetocrystalline anisotropy of Laves phase Fe$_2$Ta$_{1-x}$W$_x$ from first principles - the effect of 3d-5d hybridisation,"The magnetic properties of Fe$_2$Ta and Fe$_2$W in the hexagonal Laves phase
+are computed using density functional theory in the generalised gradient
+approximation, with the full potential linearised augmented plane wave method.
+The alloy Fe$_2$Ta$_{1-x}$W$_x$ is studied using the virtual crystal
+approximation to treat disorder. Fe$_2$Ta is found to be ferromagnetic with a
+saturation magnetization of $\mu_0 M_\text{s} = 0.66~\mathrm{T}$ while, in
+contrast to earlier computational work, Fe$_2$W is found to be ferrimagnetic
+with $\mu_0 M_\text{s} = 0.35~\mathrm{T}$. The transition from the ferri- to
+the ferromagnetic state occurs for $x \leq 0.1$. The magnetocrystalline
+anisotropy energy (MAE) is calculated to $1.25~\mathrm{MJ/m^3}$ for Fe$_2$Ta
+and $0.87~\mathrm{MJ/m^3}$ for Fe$_2$W. The MAE is found to be smaller for all
+values $x$ in Fe$_2$Ta$_{1-x}$W$_x$ than for the end compounds and it is
+negative (in-plane anisotropy) for $0.1 \leq x \leq 0.9$. The MAE is carefully
+analysed in terms of the electronic structure. Even though there are weak 5d
+contributions to the density of states at the Fermi energy in both end
+compounds, a reciprocal space analysis, using the magnetic force theorem,
+reveals that the MAE originates mainly from regions of the Brillouin zone with
+strong 3d-5d hybridisation near the Fermi energy. Perturbation theory and its
+applicability in relation to the MAE is discussed.",1612.06802v1
+2019-04-10,Optical excitation of propagating magnetostatic waves in an epitaxial Galfenol film by an ultrafast magnetic anisotropy change,"Using a time-resolved optically-pumped scanning optical microscopy technique
+we demonstrate the laser-driven excitation and propagation of spin waves in a
+20-nm film of a ferromagnetic metallic alloy Galfenol epitaxially grown on a
+GaAs substrate. In contrast to previous all-optical studies of spin waves we
+employ laser-induced thermal changes of magnetocrystalline anisotropy as an
+excitation mechanism. A tightly focused 70-fs laser pulse excites packets of
+magnetostatic surface waves with a $e^{-1}$ propagation length of 3.4 $\mu$m,
+which is comparable with that of permalloy. As a result, laser-driven
+magnetostatic spin waves are clearly detectable at distances up to 10 $\mu$m,
+which promotes epitaxial Galfenol films to the limited family of materials
+suitable for magnonic devices. A pronounced in-plane magnetocrystalline
+anisotropy of the Galfenol film offers an additional degree of freedom for
+manipulating the spin waves' parameters. Reorientation of an in-plane external
+magnetic field relative to the crystallographic axes of the sample tunes the
+frequency, amplitude and propagation length of the excited waves.",1904.05171v2
+2021-01-10,Magnetic anisotropy in van-der-Waals ferromagnet VI3,"A comprehensive study of magnetocrystalline anisotropy of a layered
+van-der-Waals ferromagnet VI3 was performed. We measured angular dependences of
+the torque and magnetization with respect to the direction of the applied
+magnetic field within the ""ac"" plane perpendicular to and within the basal ab
+plane, respectively. A two-fold butterfly-like signal was detected by
+magnetization in the perpendicular ""ac"" plane. This signal symmetry remains
+conserved throughout all magnetic regimes as well as through the known
+structural transition down to the lowest temperatures. The maximum of the
+magnetization signal and the resulting magnetization easy axis is significantly
+tilted from the principal c axis by ~40{\deg}. The close relation of the
+magnetocrystalline anisotropy to the crystal structure was documented. In
+contrast, a two-fold-like angular signal was detected in the paramagnetic
+region within the ab plane in the monoclinic phase, which transforms into a
+six-fold-like signal below the Curie temperature TC. With further cooling,
+another six-fold-like signal with an angular shift of ~30{\deg} grows
+approaching TFM. Below TFM, in the triclinic phase, the original six-fold-like
+signal vanishes, being replaced by a secondary six-fold-like signal with an
+angular shift of ~30{\deg}.",2101.03542v1
+2022-04-15,"First-principles Calculation of Magnetocrystalline Anisotropy of Y(Co,Fe,Ni,Cu)$_5$ Based on Full-potential KKR Green's Function Method","The performance of permanent magnets YCo$_5$ can be improved by replacing
+cobalt with other elements, such as iron, copper, and nickel. In order to
+determine its optimum composition, it is necessary to perform systematic
+theoretical calculations in a consistent framework. In this study, we
+calculated the magnetocrystalline anisotropy constant $K_{\rm u}$ of
+Y(Co$_{1-x-y}$Fe$_{x}$Cu$_{y}$)$_3$(Co$_{1-z}$Ni$_{z}$)$_2$ on the basis of the
+full-potential Korringa-Kohn-Rostoker Green's function method in conjunction
+with the coherent potential approximation. The calculated $K_{\rm u}$ of
+YCo$_5$ was smaller than the experimental value because of a missing
+enhancement due to orbital polarization. Although the value of $K_{\rm u}$ of
+Y(Co$_{1-x-y}$Fe$_{x}$Cu$_{y}$)$_3$(Co$_{1-z}$Ni$_{z}$)$_2$ was systematically
+underestimated compared to their experimental counterparts, the doping effect
+can be analyzed within a consistent framework. The results have shown that
+YFe$_3$Co$_2$ has much higher $K_{\rm u}=5.00$ MJ/m$^3$ than pristine YCo$_5$
+($K_{\rm u}=1.82$ MJ/m$^3$), and that nickel as a stabilization element
+decreases $K_{\rm u}$ and magnetization in YFe$_3$(Co$_{1-z}$Ni$_z$)$_2$.
+However, the anisotropy field of $z\sim0.5$ can compete with the value of
+YCo$_5$.",2204.07384v1
+2006-01-04,Prospect for room temperature tunneling anisotropic magnetoresistance effect: density of states anisotropies in CoPt systems,"Tunneling anisotropic magnetoresistance (TAMR) effect, discovered recently in
+(Ga,Mn)As ferromagnetic semiconductors, arises from spin-orbit coupling and
+reflects the dependence of the tunneling density of states in a ferromagnetic
+layer on orientation of the magnetic moment. Based on ab initio relativistic
+calculations of the anisotropy in the density of states we predict sizable TAMR
+effects in room-temperature metallic ferromagnets. This opens prospect for new
+spintronic devices with a simpler geometry as these do not require
+antiferromagnetically coupled contacts on either side of the tunnel junction.
+We focus on several model systems ranging from simple hcp-Co to more complex
+ferromagnetic structures with enhanced spin-orbit coupling, namely bulk and
+thin film L1$_0$-CoPt ordered alloys and a monatomic-Co chain at a Pt surface
+step edge. Reliability of the predicted density of states anisotropies is
+confirmed by comparing quantitatively our ab initio results for the
+magnetocrystalline anisotropies in these systems with experimental data.",0601071v1
+2009-04-06,"Magneto crystalline anisotropies in (Ga,Mn)As: A systematic theoretical study and comparison with experiment","We present a theoretical survey of magnetocrystalline anisotropies in
+(Ga,Mn)As epilayers and compare the calculations to available experimental
+data. Our model is based on an envelope function description of the valence
+band holes and a spin representation for their kinetic-exchange interaction
+with localised electrons on Mn ions, treated in the mean-field approximation.
+For epilayers with growth induced lattice-matching strains we study in-plane to
+out-of-plane easy-axis reorientations as a function of Mn local-moment
+concentration, hole concentration, and temperature. Next we focus on the
+competition of in-plane cubic and uniaxial anisotropies. We add an in-plane
+shear strain to the effective Hamiltonian in order to capture measured data in
+bare, unpatterned epilayers, and we provide microscopic justification for this
+approach. The model is then extended by an in-plane uniaxial strain and used to
+directly describe experiments with strains controlled by postgrowth lithography
+or attaching a piezo stressor. The calculated easy-axis directions and
+anisotropy fields are in semiquantitative agreement with experiment in a wide
+parameter range.",0904.0993v1
+2015-09-14,From soft to hard magnetic Fe-Co-B by spontaneous strain: A combined first principle and thin film study,"In order to convert the well-known Fe-Co-B alloy from a soft to a hard
+magnet, we propose tetragonal strain by interstitial boron. Density functional
+theory reveals that when B atoms occupy octahedral interstitial sites, the bcc
+Fe-Co lattice is strained spontaneously. Such highly distorted Fe-Co is
+predicted to reach a strong magnetocrystalline anisotropy which may compete
+with shape anisotropy. Probing this theoretical suggestion experimentally,
+epitaxial films are examined. A spontaneous strain up to 5 % lattice distortion
+is obtained for B contents up to 4 at%, which leads to uniaxial anisotropy
+constants exceeding 0.5 MJ/m^3. However, a further addition of B results in a
+partial amorphization, which degrades both anisotropy and magnetization.",1509.04126v1
+2015-10-19,Minimum Anisotropy of a Magnetic Nanoparticle out of Equilibrium,"In this article we study magnetotransport in single nanoparticles of Ni,
+Py=Ni$_{0.8}$Fe$_{0.2}$, Co, and Fe, with volumes $15\pm 6$nm$^3$, using
+sequential electron tunneling at 4.2K temperature. We measure current versus
+magnetic field in the ensembles of nominally the same samples, and obtain the
+abundances of magnetic hysteresis. The hysteresis abundance varies among the
+metals as Ni:Py:Co:Fe=4\,:50\,:100\,:100(\%), in good correlation with the
+magnetostatic and magnetocrystalline anisotropy. The abrupt change in the
+hysteresis abundance among these metals suggests a concept of minimum magnetic
+anisotropy required for magnetic hysteresis, which is found to be $\approx
+13$meV. The minimum anisotropy is explained in terms of the residual
+magnetization noise arising from the spin-orbit torques generated by sequential
+electron tunneling. The magnetic hysteresis abundances are weakly dependent on
+the tunneling current through the nanoparticle, which we attribute to current
+dependent damping.",1510.05325v1
+2016-03-11,Atomic-scale control of magnetic anisotropy via novel spin-orbit coupling effect in La2/3Sr1/3MnO3/SrIrO3 superlattices,"Magnetic anisotropy (MA) is one of the most important material properties for
+modern spintronic devices. Conventional manipulation of the intrinsic MA, i.e.
+magnetocrystalline anisotropy (MCA), typically depends upon crystal symmetry.
+Extrinsic control over the MA is usually achieved by introducing shape
+anisotropy or exchange bias from another magnetically ordered material. Here we
+demonstrate a pathway to manipulate MA of 3d transition metal oxides (TMOs) by
+digitally inserting non-magnetic 5d TMOs with pronounced spin-orbit coupling
+(SOC). High quality superlattices comprised of ferromagnetic La2/3Sr1/3MnO3
+(LSMO) and paramagnetic SrIrO3 (SIO) are synthesized with the precise control
+of thickness at atomic scale. Magnetic easy axis reorientation is observed by
+controlling the dimensionality of SIO, mediated through the emergence of a
+novel spin-orbit state within the nominally paramagnetic SIO.",1603.03794v2
+2018-08-03,Ferromagnetic resonance in thin films - cross-validation analysis of numerical solutions of Smit-Beljers equation. Application to GaMnAs,"(Dated: August 3, 2018) The new method of numerical analysis of experimental
+ferromagnetic resonance (FMR) spectra in thin films is developed and applied to
+(Ga,Mn)As thin films. Specifically, it starts with the finding of numerical
+solutions of Smit-Beljers (SB) equation and continues with their subsequent
+statistical analysis within the cross-validation (CV) approach taken from
+machine learning techniques. As a result of this treatment, we are able to
+reinterpret the available FMR experimental results in diluted ferromagnetic
+semiconductor (Ga,Mn)As thin films with the resulting determination of
+magnetocrystalline anisotropy constants. The outcome of CV analysis points out
+that it is necessary to take into account terms describing the bulk cubic
+anisotropy up to the fourth order to reproduce FMR experimental results for
+(Ga,Mn)As correctly. This finding contradicts the wide-spread conviction in the
+literature that only first order cubic anisotropy term is important in this
+material. We also provide numerical values of these higher order cubic
+anisotropy constants for (Ga,Mn)As thin films resulting from SB-CV approach.",1808.01347v1
+2019-02-14,Vectorial observation of the spin Seebeck effect in epitaxial NiFe$_2$O$_4$ thin films with various magnetic anisotropy contributions,"We have developed a vectorial type of measurement for the spin Seebeck effect
+(SSE) in epitaxial NiFe$_2$O$_4$ thin films which have been grown by pulsed
+laser deposition on MgGa$_2$O$_4$ (MGO) with (001) and (011) orientation as
+well as CoGa$_2$O$_4$ (011) (CGO), thus varying the lattice mismatch and
+crystal orientation. We confirm that a large lattice mismatch leads to strain
+anisotropy in addition to the magnetocrystalline anisotropy in the thin films
+using vibrating sample magnetometry and ferromagnetic resonance measurements.
+Moreover, we show that the existence of a magnetic strain anisotropy in
+NiFe$_2$O$_4$ thin films significantly impacts the shape and magnitude of the
+magnetic-field-dependent SSE voltage loops. We further demonstrate that
+bidirectional field-dependent SSE voltage curves can be utilized to reveal the
+complete magnetization reversal process, which establishes a vectorial
+magnetometry technique based on a spin caloric effect.",1902.05384v2
+2019-05-30,Predicting New Iron Garnet Thin Films with Perpendicular Magnetic Anisotropy,"Perpendicular magnetic anisotropy (PMA) is a necessary condition for many
+spintronic applications like spin-orbit torques switching, logic and memory
+devices. An important class of magnetic insulators with low Gilbert damping at
+room temperature are iron garnets, which only have a few PMA types such as
+terbium and samarium iron garnet. More and stable PMA garnet options are
+necessary for researchers to be able to investigate new spintronic phenomena.
+In this study, we predict 20 new substrate/magnetic iron garnet film pairs with
+stable PMA at room temperature. The effective anisotropy energies of 10
+different garnet films that are lattice-matched to 5 different commercially
+available garnet substrates have been calculated using shape, magnetoelastic
+and magnetocrystalline anisotropy terms. Strain type, tensile or compressive
+depending on substrate choice, as well as the sign and the magnitude of the
+magnetostriction constants of garnets determine if a garnet film may possess
+PMA. We show the conditions in which Samarium, Gadolinium, Terbium, Holmium,
+Dysprosium and Thulium garnets may possess PMA on the investigated garnet
+substrate types. Guidelines for obtaining garnet films with low damping are
+presented. New PMA garnet films with tunable saturation moment and field may
+improve spin-orbit torque memory and compensated magnonic thin film devices.",1905.13042v1
+2019-08-21,"Two-dimensional Ferromagnetic van der Waals CrX3 (X=Cl, Br, I) Monolayers with Enhanced Anisotropy and Curie Temperature","Among the recently widely studied van der Waals layered magnets CrX3 (X=Cl,
+Br, I), CrCl3 monolayer (ML) is particularly puzzling as it is solely shown by
+experiments to have an in-plane magnetic easy axis and, furthermore, all of
+previous first-principles calculation results contradict this. Through
+systematical first-principles calculations,we unveil that its in-plane shape
+anisotropy that dominates over its weak perpendicular magnetocrystalline
+anisotropy is responsible for the in-plane magnetic easy axis of CrCl3 ML. To
+tune the in-plane ferromagnetism of CrCl3 ML into the desirable perpendicular
+one, we propose substituting Cr with isovalent tungsten (W). We find that
+CrWCl6 has a strong perpendicular magnetic anisotropy and a high Curie
+temperature up to 76 K. Our work not only gives insight into understanding the
+two-dimensional ferromagnetism of van der Waals MLs but also sheds new light on
+engineering their performances for nanodevices.",1908.07710v2
+2022-05-16,Magnetic neutron scattering from spherical nanoparticles with Neel surface anisotropy: Analytical treatment,"The magnetization profile and the related magnetic small-angle neutron
+scattering cross section of a single spherical nanoparticle with Neel surface
+anisotropy is analytically investigated. We employ a Hamiltonian that comprises
+the isotropic exchange interaction, an external magnetic field, a uniaxial
+magnetocrystalline anisotropy in the core of the particle, and the Neel
+anisotropy at the surface. Using a perturbation approach, the determination of
+the magnetization profile can be reduced to a Helmholtz equation with Neumann
+boundary condition, whose solution is represented by an infinite series in
+terms of spherical harmonics and spherical Bessel functions. From the resulting
+infinite series expansion, we analytically calculate the Fourier transform,
+which is algebraically related to the magnetic small-angle neutron scattering
+cross section. The approximate analytical solution is compared to the numerical
+solution using the Landau-Lifshitz equation, which accounts for the full
+nonlinearity of the problem.",2205.07549v1
+2022-06-02,Anisotropic Gigahertz Antiferromagnetic Resonances of the Easy-Axis van der Waals Antiferromagnet CrSBr,"We report measurements of antiferromagnetic resonances in the van der Waals
+easy-axis antiferromagnet CrSBr. The interlayer exchange field and
+magnetocrystalline anisotropy fields are comparable to laboratory magnetic
+fields, allowing a rich variety of gigahertz-frequency dynamical modes to be
+accessed. By mapping the resonance frequencies as a function of the magnitude
+and angle of applied magnetic field we identify the different regimes of
+antiferromagnetic dynamics. The spectra show good agreement with a
+Landau-Lifshitz model for two antiferromagnetically-coupled sublattices,
+accounting for inter-layer exchange and triaxial magnetic anisotropy. Fits
+allow us to quantify the parameters governing the magnetic dynamics: at 5 K,
+the interlayer exchange field is $\mu_0 H_E =$ 0.395(2) T, and the hard and
+intermediate-axis anisotropy parameters are $\mu_0 H_c =$ 1.30(2) T and $\mu_0
+H_a =$ 0.383(7) T. The existence of within-plane anisotropy makes it possible
+to control the degree of hybridization between the antiferromagnetic resonances
+using an in-plane magnetic field.",2206.01286v2
+2022-08-04,Electric-field induced magnetic-anisotropy transformation to achieve spontaneous valley polarization,"Valleytronics has been widely investigated for providing new degrees of
+freedom to future information coding and processing. Here, it is proposed that
+valley polarization can be achieved by electric field induced magnetic
+anisotropy (MA) transformation. Through the first-principle calculations, our
+idea is illustrated by a concrete example of $\mathrm{VSi_2P_4}$ monolayer. The
+increasing electric field can induce a transition of MA from in-plane to
+out-of-plane by changing magnetic anisotropy energy (MAE) from negative to
+positive value, which is mainly due to increasing magnetocrystalline anisotropy
+(MCA) energy. The out-of-plane magnetization is in favour of spontaneous valley
+polarization in $\mathrm{VSi_2P_4}$. Within considered electric field range,
+$\mathrm{VSi_2P_4}$ is always ferromagnetic (FM) ground state. In a certain
+range of electric field, the coexistence of semiconductor and out-of-plane
+magnetization makes $\mathrm{VSi_2P_4}$ become a true ferrovalley (FV)
+material. The anomalous valley Hall effect (AVHE) can be observed under
+in-plane and out-of-plane electrical field in $\mathrm{VSi_2P_4}$. Our works
+pave the way to design the ferrovalley material by electric field.",2208.02425v1
+1995-08-25,Simple theory for spin-lattice relaxation in metallic rare earth ferromagnets,"The spin-lattice relaxation time $\tau_{SL}$ is a key quantity both for the
+dynamical response of ferromagnets excited by laser pulses and as the speed
+limit of magneto-optical recording. Extending the theory for the electron
+paramagnetic resonance of magnetic impurities to spin-lattice relaxation in
+ferromagnetic rare earths we calculate $\tau_{SL}$ for Gd and find a value of
+48 ps in very good agreement with time-resolved spin-polarized photoemission
+experiments. We argue that the time scale for $\tau_{SL}$ in metals is
+essentially given by the spin-orbit induced magnetocrystalline anisotropy
+energy.",9508120v1
+1998-08-21,Spin Reorientations Induced by Morphology Changes in Fe/Ag(001),"By means of magneto-optical Kerr effect we observe spin reorientations from
+in-plane to out-of-plane and vice versa upon annealing thin Fe films on Ag(001)
+at increasing temperatures. Scanning tunneling microscopy images of the
+different Fe films are used to quantify the surface roughness. The observed
+spin reorientations can be explained with the experimentally acquired roughness
+parameters by taking into account the effect of roughness on both the magnetic
+dipolar and the magnetocrystalline anisotropy.",9808236v1
+1999-12-22,Observation of domain wall resistivity in $\rm SrRuO_3$,"$\rm SrRuO_3$ is an itinerant ferromagnet with $T_c \sim 150 \rm K$. When
+$\rm SrRuO_3$ is cooled through $T_c$ in zero applied magnetic field, a stripe
+domain structure appears whose orientation is uniquely determined by the large
+uniaxial magnetocrystalline anisotropy. We find that the ferromagnetic domain
+walls clearly enhance the resisitivity of $\rm SrRuO_3$ and that the
+enhancement has different temperature dependence for currents parallel and
+perpendicular to the domain walls. We discuss possible interpretations of our
+results.",9912404v1
+2006-05-31,"Spin injection from perpendicular magnetized ferromagnetic $δ$-MnGa into (Al,Ga)As heterostructures","Electrical spin injection from ferromagnetic $\delta$-MnGa into an (Al,Ga)As
+p-i-n light emitting diode (LED) is demonstrated. The $\delta$-MnGa layers show
+strong perpendicular magnetocrystalline anisotropy, enabling detection of spin
+injection at remanence without an applied magnetic field. The bias and
+temperature dependence of the spin injection are found to be qualitatively
+similar to Fe-based spin LED devices. A Hanle effect is observed and
+demonstrates complete depolarization of spins in the semiconductor in a
+transverse magnetic field.",0606013v1
+2006-07-17,Magnetic transition and magnetic structure of Sr4Ru3O10,"We have investigated the magnetic transition and magnetic structure of
+triple-layered ruthenate Sr4Ru3O10 directly using neutron scattering
+techniques. Only one ferromagnetic phase is observed, and previously proposed
+antiferromagnetic phase transitions are ruled out. The complex anisotropic
+magnetotransport, magnetization and in-plane metamagnetic behaviors of this
+quasi two-dimensional (2D) material are most likely due to magnetic domain
+processes with strong magnetocrystalline anisotropy and a strongly anisotropic
+demagnetization factor.",0607428v1
+2008-04-26,Spin-torque oscillator based on tilted magnetization of the fixed layer,"The spin torque oscillator (STO), where the magnetization of the fixed layer
+is tilted out of the film plane, is capable of strong microwave signal
+generation in zero magnetic field. Through numerical simulations of the
+Landau-Lifshitz-Gilbert-Slonczewski equations, within a macro-spin
+approximation, we study the microwave signal generation as a function of drive
+current for two realistic tilt angles. The tilt magnetization of the fixed
+layer can be achieved by using a material with high out-of-plane
+magnetocrystalline anisotropy, such as L10 FePt.",0804.4213v1
+2008-08-06,Surface Magnetoelectric Effect in Ferromagnetic Metal Films,"A surface magnetoelectric effect is revealed by density-functional
+calculations that are applied to ferromagnetic Fe(001), Ni(001) and Co(0001)
+films in the presence of external electric field. The effect originates from
+spin-dependent screening of the electric field which leads to notable changes
+in the surface magnetization and the surface magnetocrystalline anisotropy.
+These results are of considerable interest in the area of
+electrically-controlled magnetism and magnetoelectric phenomena.",0808.0841v1
+2008-10-26,The magnetoresistance tensor of La(0.8)Sr(0.2)MnO(3),"We measure the temperature dependence of the anisotropic magnetoresistance
+(AMR) and the planar Hall effect (PHE) in c-axis oriented epitaxial thin films
+of La(0.8)Sr(0.2)MnO(3), for different current directions relative to the
+crystal axes, and show that both AMR and PHE depend strongly on current
+orientation. We determine a magnetoresistance tensor, extracted to 4th order,
+which reflects the crystal symmetry and provides a comprehensive description of
+the data. We extend the applicability of the extracted tensor by determining
+the bi-axial magnetocrystalline anisotropy in our samples.",0810.4679v1
+2011-01-05,Four-state nanomagnetic logic using multiferroics,"The authors show how to implement a 4-state universal logic gate (NOR) using
+three strain-coupled magnetostrictive-piezoelectric multiferroic nanomagnets
+(e.g. Ni/PZT) with biaxial magnetocrystalline anisotropy. Two of the
+nanomagnets encode the 2-state input bits in their magnetization orientations
+and the third nanomagnet produces the output bit via dipole interaction with
+the input nanomagnets. A voltage pulse alternating between -0.2 V and +0.2 V is
+applied to the PZT layer of the third nanomagnet and generates alternating
+tensile and compressive stress in its Ni layer to produce the output bit, while
+dissipating ~ 57,000 kT (0.24 fJ) of energy per gate operation.",1101.0980v1
+2011-03-25,Temperature dependence of spin resonance in cobalt substituted NiZnCu ferrites,"Cobalt substitutions were investigated in Ni0.4Zn0.4Cu0.2Fe2O4 ferrites,
+initial complex permeability was then measured from 1 MHz to 1 GHz. It appears
+that cobalt substitution led to a decrease in the permeability and an increase
+in the \mus\timesfr factor. As well, it gave to the permeability spectrum a
+sharp resonance character. We also observed a spin reorientation occurring at a
+temperature depending on the cobalt content. Study of the complex permeability
+versus temperature highlighted that the most resonant character was obtained at
+this temperature. This shows that cobalt contribution to second order
+magnetocrystalline anisotropy plays a leading role at this temperature.",1103.5024v1
+2011-11-27,Large Coercivity in Nanostructured Rare-earth-free MnxGa Films,"The magnetic hysteresis of MnxGa films exhibit remarkably large coercive
+fields as high as 2.5 T when fabricated with nanoscale particles of a suitable
+size and orientation. This coercivity is an order of magnitude larger than in
+well-ordered epitaxial film counterparts and bulk materials. The enhanced
+coercivity is attributed to the combination of large magnetocrystalline
+anisotropy and ~ 50 nm size nanoparticles. The large coercivity is also
+replicated in the electrical properties through the anomalous Hall effect. The
+magnitude of the coercivity approaches that found in rare-earth magnets, making
+them attractive for rare-earth-free magnet applications.",1111.6267v1
+2013-07-09,Giant magnetostriction in Tb-doped Fe83Ga17 melt-spun ribbons,"Giant magnetostriction is achieved in the slightly Tb-doped Fe83Ga17
+melt-spun ribbons. The tested average perpendicular magnetostriction is -886
+ppm along the melt-spun ribbon direction in the Fe82.89Ga16.88Tb0.23 alloy. The
+calculated parallel magnetostriction is 1772 ppm, more than 4 times as large as
+that of binary Fe83Ga17 alloy. The enhanced magnetostriction should be
+attributed to a small amount of Tb solution into the A2 matrix phase during
+rapid solidification. The localized strong magnetocrystalline anisotropy of Tb
+element is suggested to cause the giant magnetostriction.",1307.2385v1
+2016-11-01,Spin-Mechanical Inertia in Antiferromagnet,"Angular momentum conservation has served as a guiding principle in the
+interplay between spin dynamics and mechanical rotations. However, in an
+antiferromagnet with vanishing magnetization, new fundamental rules are
+required to properly describe spin-mechanical phenomena. Here we show that the
+N\'eel order dynamics affects the mechanical motion of a rigid body by
+modifying its inertia tensor in the presence of strong magnetocrystalline
+anisotropy. This effect depends on temperature when magnon excitations are
+considered. Such a spin-mechanical inertia can produce measurable consequences
+at small scales.",1611.00100v3
+2017-07-29,Thermodynamics of the SmCo5 compound doped with Fe and Ni: an ab initio study,"SmCo5 permanent magnets exhibit enormous uniaxial magnetocrystalline
+anisotropy energy and have a high Curie temperature. However, a low energy
+product presents a significant drawback in the performance of SmCo5 permanent
+magnets. In order to increase the energy product in SmCo5, we propose
+substituting fixed amount of cobalt with iron in a new magnet, SmFe3CoNi, where
+inclusion of nickel metal makes this magnet thermodynamically stable. We
+further discuss some basic theoretical magnetic properties of the SmCo5
+compound.",1707.09447v1
+2018-08-01,Long range dynamical coupling between magnetic adatoms mediated by a 2D topological insulator,"We study the spin excitation spectra and the dynamical exchange coupling
+between iron adatoms on a Bi bilayer nanoribbon. We show that the topological
+character of the edge states is preserved in the presence of the magnetic
+adatoms. Nevertheless, they couple significantly to the edge spin currents, as
+witnessed by the large and long-ranged dynamical coupling we obtain in our
+calcula- tions. The large effective magnetocrystalline anisotropy of the
+magnetic adatoms combined with the transport properties of the topologically
+protected edge states make this system a strong candidate for implementation of
+spintronics devices and quantum information and/or computation protocols.",1808.00347v1
+2019-03-05,Electronic structure and magnetism of transition metal dihalides: bulk to monolayer,"Based on first-principles calculations, the evolution of the electronic and
+magnetic properties of transition metal dihalides MX$_2$ (M= V, Mn, Fe, Co, Ni;
+X = Cl, Br, I) is analyzed from the bulk to the monolayer limit. A variety of
+magnetic ground states is obtained as a result of the competition between
+direct exchange and superexchange. The results predict that FeX$_2$, NiX$_2$,
+CoCl$_2$ and CoBr$_2$ monolayers are ferromagnetic insulators with sizable
+magnetocrystalline anisotropies. This makes them ideal candidates for robust
+ferromagnetism at the single layer level. Our results also highlight the
+importance of spin-orbit coupling to obtain the correct ground state.",1903.01789v1
+2019-11-08,Magnetic i-MXene: a new class of multifunctional two-dimensional materials,"Based on density functional theory calculations, we investigated the
+two-dimensional in-plane ordered MXene (i-MXenes), focusing particularly on the
+magnetic properties. It is observed that robust two-dimensional magnetism can
+be achieved by alloying nonmagnetic MXene with magnetic transition metal atoms.
+Moreover, both the magnetic ground states and the magnetocrystalline anisotropy
+energy of the i-MXenes can be effectively manipulated by strain, indicating
+strong piezomagnetic effect. Further studies on the transport properties reveal
+that i-MXenes provide an interesting playground to realize large thermoelectric
+response, antiferromagnetic topological insulator, and spin-gapless
+semiconductors. Thus, i-MXenes are a new class of multifunctional
+two-dimensional magnetic materials which are promising for future spintronic
+applications.",1911.03470v1
+2021-06-09,Unraveling the role of the magnetic anisotropy on thermoelectric response: a theoretical and experimental approach,"Magnetic anisotropies have key role to taylor magnetic behavior in
+ferromagnetic systems. Further, they are also essential elements to manipulate
+the thermoelectric response in Anomalous Nernst (ANE) and Longitudinal Spin
+Seebeck systems (LSSE). We propose here a theoretical approach and explore the
+role of magnetic anisotropies on the magnetization and thermoelectric response
+of noninteracting multidomain ferromagnetic systems. The magnetic behavior and
+the thermoelectric curves are calculated from a modified Stoner Wohlfarth model
+for an isotropic system, a uniaxial magnetic one, as well as for a system
+having a mixture of uniaxial and cubic magnetocrystalline magnetic
+anisotropies. It is verified remarkable modifications of the magnetic behavior
+with the anisotropy and it is shown that the thermoelectric response is
+strongly affected by these changes. Further, the fingerprints of the energy
+contributions to the thermoelectric response are disclosed. To test the
+robustness of our theoretical approach, we engineer films having the specific
+magnetic properties and compare directly experimental data with theoretical
+results. Thus, experimental evidence is provided to confirm the validity of our
+theoretical approach. The results go beyond the traditional reports focusing on
+magnetically saturated films and show how the thermoelectric effect behaves
+during the whole magnetization curve. Our findings reveal a promising way to
+explore the ANE and LSSE effects as a powerful tool to study magnetic
+anisotropies, as well as to employ systems with magnetic anisotropy as sensing
+or elements in technological applications.",2106.05063v1
+1999-03-19,Field dependence of the temperature at the peak of the ZFC magnetization,"The effect of an applied magnetic field on the temperature at the maximum of
+the ZFC magnetization, $M_{ZFC}$, is studied using the recently obtained
+analytic results of Coffey et al. (Phys. Rev. Lett. {\bf 80}(1998) 5655) for
+the prefactor of the N\'{e}el relaxation time which allow one to precisely
+calculate the prefactor in the N\'{e}el-Brown model and thus the blocking
+temperature as a function of the coefficients of the Taylor series expansion of
+the magnetocrystalline anisotropy. The present calculations indicate that even
+a precise determination of the prefactor in the N\'{e}el-Brown theory, which
+always predicts a monotonic decrease of the relaxation time with increasing
+field, is insufficient to explain the effect of an applied magnetic field on
+the temperature at the maximum of the ZFC magnetization. On the other hand, we
+find that the non linear field-dependence of the magnetization along with the
+magnetocrystalline anisotropy appears to be of crucial importance to the
+existence of this maximum.",9903302v3
+2007-03-29,Easy-plane magnetocrystalline anisotropy in the multi-step metamagnet CeIr3Si2,"Highly anisotropic properties of CeIr$_3$Si$_2$ have been observed by the
+magnetization $M$($B$), electrical resistivity $\rho$, and specific heat
+measurements on a single-crystalline sample. This compound with an orthorhombic
+structure having zigzag chains of Ce ions along the a-axis undergos magnetic
+transitions at 3.9 K and 3.1 K. At 0.3 K, metamagnetic transitions occur at
+0.68 T and 1.3 T for $B$$//$$b$ and 0.75 T for $B$$//$$c$. Easy-plane
+magnetocrystalline anisotropy is manifested as $M$($B//b$) $\cong$ $M$($B//c$)
+$\cong$ 11$M$($B//a$) at $B$ = 5 T. Electrical resistivity is also anisotropic;
+$\rho_{b}$ $\cong$ $\rho_{c}$ $\ge$ 2$\rho_{a}$. The magnetic part of $\rho$
+exhibits a double-peak structure with maxima at 15 K and 250 K. The magnetic
+entropy at $T$$\rm_{N1}$ = 3.9 K is a half of $R$ln2. These observations are
+ascribable to the combination of the Kondo effect with $T$$\rm_{K}$ $\sim$ 20 K
+and a strong crystal field effect. The analysis of $M$($B$) and paramagnetic
+susceptibility revealed unusually large energy splitting of 500 K and 1600 K
+for the two excited doublets, respectively.",0703776v1
+2012-03-28,"Multifunctional L10-Mn1.5Ga films with ultrahigh coercivity, giant perpendicular magnetocrystalline anisotropy and large magnetic energy product","We present the fascinating magnetic properties in homogenous noble-metal-free
+and rare-earth-free L10-Mn1.5Ga epitaxial films on GaAs (001), including
+ultrahigh perpendicular coercivity remarkably tunable from 8.1 to 42.8 kOe,
+giant perpendicular magnetocrystalline anisotropy with a maximum of 22.9
+Merg/cc, easily controllable magnetization from 27.3 to 270.5 emu/cc, excellent
+squareness exceeding 0.94 and large magnetic energy product up to 2.6 MGOe.
+These magnificent room-temperature magnetic characteristics make our
+L10-Mn1.5Ga films multifunctional as outstanding and cost-effective alternative
+for not only perpendicular magnetic recording bits with areal density over 30
+Tb inch-2 and thermal stability over 60 years, but variety of novel devices
+with high magnetic-noise immunity and thermal stability like spin-torque MRAMs
+and oscillators pillars below 5 nm in dimension, and giant magnetoresistance
+sensors able to measure high fileds up to 42 kOe . Moreover, this kind of
+materials can also be expected as permanent magnets for replacing the expensive
+rare-earth magnets widely used today.",1203.6176v5
+2012-05-24,Enhancing magnetocrystalline anisotropy of the Fe70Pd30 magnetic shape memory alloy by adding Cu,"Strained epitaxial growth provides the opportunity to understand the
+dependence of intrinsic and extrinsic properties of functional materials at
+frozen intermediate stages of a phase transformation. In this study, a
+combination of thin film experiments and first-principles calculations yields
+the binding energy and magnetic properties of tetragonal Fe70Pd30-xCux
+ferromagnetic shape memory thin films with x = 0, 3, 7 and structures ranging
+from bcc to beyond fcc (1.07<c/a_bct<1.57). We find that Cu enhances the
+quality of epitaxial growth, while spontaneous polarisation and Curie
+temperature are only moderately lowered as expected from our calculations.
+Beyond c/a_bct>1.41 the samples undergo structural relaxations through adaptive
+nanotwinning. For all tetragonal structures, we observe a significant increase
+of the magnetocrystalline anisotropy constant K1, which reaches a maximum of
+K1=-2.4*10^5 Jm^-3 at room temperature around c/a_bct=1.33 and is thus even
+larger than for binary Fe70Pd30 and the prototype Ni-Mn-Ga magnetic shape
+memory system. Since K1 represents the driving force for variant reorientation
+in magnetic shape memory systems, we conclude that Fe-Pd-Cu alloys offer a
+promising route towards microactuators applications with significantly improved
+work output.",1205.5422v1
+2017-02-27,Large magnetocrystalline anisotropy in tetragonally distorted Heuslers: a systematic study,"With a view to the design of hard magnets without rare earths we explore the
+possibility of large magnetocrystalline anisotropy energies in Heusler
+compounds that are unstable with respect to a tetragonal distortion. We
+consider the Heusler compounds Fe$_2$YZ with Y = (Ni, Co, Pt), and Co$_2$YZ
+with Y = (Ni, Fe, Pt) where, in both cases, Z = (Al, Ga, Ge, In, Sn). We find
+that for the Co$_2$NiZ, Co$_2$PtZ, and Fe$_2$PtZ families the cubic phase is
+always, at $T=0$, unstable with respect to a tetragonal distortion, while, in
+contrast, for the Fe$_2$NiZ and Fe$_2$CoZ families this is the case for only 2
+compounds -- Fe$_2$CoGe and Fe$_2$CoSn. For all compounds in which a tetragonal
+distortion occurs we calculate the MAE finding remarkably large values for the
+Pt containing Heuslers, but also large values for a number of the other
+compounds (e.g. Co$_2$NiGa has an MAE of -2.11~MJ/m$^3$). The tendency to a
+tetragonal distortion we find to be strongly correlated with a high density of
+states at the Fermi level in the cubic phase. As a corollary to this fact we
+observe that upon doping compounds for which the cubic structure is stable such
+that the Fermi level enters a region of high DOS, a tetragonal distortion is
+induced and a correspondingly large value of the MAE is then observed.",1702.08150v1
+2018-04-16,Strong orientation dependent spin-orbit torque in antiferromagnet Mn2Au,"Antiferromagnets with zero net magnetic moment, strong anti-interference and
+ultrafast switching speed have potential competitiveness in high-density
+information storage. Body centered tetragonal antiferromagnet Mn2Au with
+opposite spin sub-lattices is a unique metallic material for N\'eel-order
+spin-orbit torque (SOT) switching. Here we investigate the SOT switching in
+quasi-epitaxial (103), (101) and (204) Mn2Au films prepared by a simple
+magnetron sputtering method. We demonstrate current induced antiferromagnetic
+moment switching in all the prepared Mn2Au films by a short current pulse at
+room temperature, whereas different orientated films exhibit distinguished
+switching characters. A direction-independent reversible switching is attained
+in Mn2Au (103) films due to negligible magnetocrystalline anisotropy energy,
+while for Mn2Au (101) and (204) films, the switching is invertible with the
+current applied along the in-plane easy axis and its vertical axis, but becomes
+attenuated seriously during initially switching circles when the current is
+applied along hard axis, because of the existence of magnetocrystalline
+anisotropy energy. Besides the fundamental significance, the strong orientation
+dependent SOT switching, which was not realized irrespective of ferromagnet and
+antiferromagnet, provides versatility for spintronics.",1804.05465v1
+2018-11-29,Magnetocrystalline Anisotropy of Fe-based $L1_0$ Alloys: Validity of Approximate Methods to Treat the Spin-Orbit Interaction,"First-principles calculations are used to gauge different levels of
+approximation to calculate the magnetocrystalline anisotropy energies (MAE) of
+five $L1_0$ FeMe alloys (Me=Co, Cu, Pd, Pt, Au). We find that a second-order
+perturbation (2PT) treatment of the spin-orbit interaction (SOI) breaks down
+for the alloys containing heavier ions, while it provides a very accurate
+description of the MAE behaviour of FeCo, FeCu, and FePd. Moreover, the
+robustness of the 2PT approximation is such that in these cases it accounts for
+the MAE of highly-non-neutral alloys and, thus, it can be used to predict their
+performance when dopants are present or when they are subject to applied gate
+bias, which are typical conditions in working magnetoelectric devices. We also
+observe that switching of the easy axis direction can be induced in some of
+these alloys by addition or removal of, at least, one electron per cell. In all
+cases, the details of the bandstructure are responsible for the finally
+observed MAE value and, therefore, suggest a limited predicting power of models
+based on the expected orbital moment values and bandwidths. Finally, we have
+confirmed the importance of various calculation parameters to obtain converged
+MAE values, in particular, those related to the accuracy of the Fermi level
+determination.",1811.12100v1
+2018-12-10,Noncollinearity effects on magnetocrystalline anisotropy for $R_2$Fe$_{14}$B magnets,"We present a theoretical investigation of the magnetocrystalline anisotropy
+(MA) in $R_2$Fe$_{14}$B ($R$ is a rare-earth element) magnets in consideration
+of the non-collinearity effect (NCE) between the $R$ and Fe magnetization
+directions. In particular, the temperature dependence of the MA of
+Dy$_2$Fe$_{14}$B magnets is detailed in terms of the $n$th-order MA constant
+(MAC) $K_n(T)$ at a temperature $T$. The features of this constant are as
+follows: $K_1(T)$ has a broad plateau in the low-temperature range and $K_2(T)$
+persistently survives in the high-temperature range. The present theory
+explains these features in terms of the NCE on the MA by using numerical
+calculations for the entire temperature range, and further, by using a
+high-temperature expansion. The high-temperature expansion for $K_n(T)$ is
+expressed in the form of
+$K_n(T)=\kappa_1(T)\left[1+\delta(T)\right][-\delta(T)]^{n-1}$, where
+$\kappa_1(T)$ is the part without the NCE and $\delta(T)$ is a correction
+factor for the NCE introduced in this study. We also provide a convenient
+expression to evaluate $K_n(T)$, which can be determined only by a second-order
+crystalline electric field coefficient and an effective exchange field.",1812.03611v2
+2019-02-14,Database of novel magnetic materials for high-performance permanent magnet development,"This paper describes the open Novamag database that has been developed for
+the design of novel Rare-Earth free/lean permanent magnets. The database
+software technologies, its friendly graphical user interface, advanced search
+tools and available data are explained in detail. Following the philosophy and
+standards of Materials Genome Initiative, it contains significant results of
+novel magnetic phases with high magnetocrystalline anisotropy obtained by three
+computational high-throughput screening approaches based on a crystal structure
+prediction method using an Adaptive Genetic Algorithm, tetragonally distortion
+of cubic phases and tuning known phases by doping. Additionally, it also
+includes theoretical and experimental data about fundamental magnetic material
+properties such as magnetic moments, magnetocrystalline anisotropy energy,
+exchange parameters, Curie temperature, domain wall width, exchange stiffness,
+coercivity and maximum energy product, that can be used in the study and design
+of new promising high-performance Rare-Earth free/lean permanent magnets. The
+results therein contained might provide some insights into the ongoing debate
+about the theoretical performance limits beyond Rare-Earth based magnets.
+Finally, some general strategies are discussed to design possible experimental
+routes for exploring most promising theoretical novel materials found in the
+database.",1902.05241v1
+2019-03-02,"A spin dynamics study in layered van der Waals single crystal, Cr$_2$Ge$_2$Te$_6$","We study the magnetisation dynamics of a bulk single crystal
+Cr$_2$Ge$_2$Te$_6$ (CGT), by means of broadband ferromagnetic resonance (FMR),
+for temperatures from 60 K down to 2 K. We determine the Kittel relations of
+the fundamental FMR mode as a function of frequency and static magnetic field
+for the magnetocrystalline easy - and hard - axis. The uniaxial
+magnetocrystalline anisotropy constant is extracted and compared with the
+saturation magnetisation, when normalised with their low temperature values.
+The ratios show a clear temperature dependence when plotted in the logarithmic
+scale, which departs from the predicted Callen-Callen power law fit of a
+straight line, where the scaling exponent \textit{n}, $K_{u}(T) \propto
+[M_s(T)/M_s(2$ K$)]^n$, contradicts the expected value of 3 for uniaxial
+anisotropy. Additionally, the spectroscopic g-factor for both the magnetic easy
+- and hard - axis exhibits a temperature dependence, with an inversion between
+20 K and 30 K, suggesting an influence by orbital angular momentum. Finally, we
+qualitatively discuss the observation of multi-domain resonance phenomena in
+the FMR spectras, at magnetic fields below the saturation magnetisation.",1903.00584v2
+2021-07-08,"Magnetic properties of 3d, 4d, and 5d transition-metal atomic monolayers in Fe/TM/Fe sandwiches: Systematic first-principles study","Previous studies have accurately determined the effect of transition metal
+point defects on the properties of bcc iron. The magnetic properties of
+transition metal monolayers on the iron surfaces have been studied equally
+intensively. In this work, we investigated the magnetic properties of the 3d,
+4d, and 5d transition-metal (TM) atomic monolayers in Fe/TM/Fe sandwiches using
+the full-potential local-orbital (FPLO) scheme of density functional theory. We
+prepared models of Fe/TM/Fe structures using the supercell method. We selected
+the total thickness of our system so that the Fe atomic layers furthest from
+the TM layer exhibit bulk iron-bcc properties. Along the direction
+perpendicular to the TM layer, we observe oscillations of spin and charge
+density. For Pt and W we obtained the largest values of perpendicular
+magnetocrystalline anisotropy and for Lu and Ir the largest values of in-plane
+magnetocrystalline anisotropy. All TM layers, except Co and Ni, reduce the
+total spin magnetic moment in the generated models, which is in good agreement
+with the Slater-Pauling curve. Density of states calculations showed that for
+Ag, Pd, Ir, and Au monolayers, a distinct van Hove singularity associated with
+TM/Fe interface can be observed at the Fermi level.",2107.03768v1
+2021-07-19,Impact of local arrangement of Fe and Ni in Fe-Ni-Al Heusler alloys on the phase stability and magnetocrystalline anisotropy,"On the basis of the density functional calculations in combination with the
+supercell approach, we report on a complete study of the influences of atomic
+arrangement and Ni substitution for Al on the ground state structural and
+magnetic properties for Fe$_2$Ni$_{1+x}$Al$_{1-x}$ Heusler alloys. We discuss
+systematically the competition between five cubic Heusler-type structures
+formed by shuffles of Fe and Ni atoms to reveal routes for improving the phase
+stability and magnetic properties, in particular magnetocrystalline
+anisotropy~(MAE). We predict that in case of Fe$_2$NiAl the ground state cubic
+structure with alternated layers of Fe and Ni possesses the highest uniaxial
+MAE which twice larger than that for the tetragonal L1$_0$ FeNi. The successive
+Ni doping at Al sublattice leads to a change of ground state structure and to
+reduce of the MAE. In addition, the phase stability against the decomposition
+into the stable systems at finite-temperatures is discussed. All~Ni-rich
+Fe$_2$Ni$_{1+x}$Al$_{1-x}$ are turned to be decomposed into a dual-phase
+consisting of Fe$_2$NiAl and FeNi.",2107.08804v2
+2021-12-08,Lattice dynamics and its effects on magnetocrystalline anisotropy energy of pristine and hole-doped YCo$_5$ from first principles,"We study the lattice dynamics effects on the phase stability and
+magnetocrystalline anisotropy (MCA) energy of CaCu$_5$-type YCo$_5$ at finite
+temperatures using first-principles calculations based on density functional
+theory (DFT). Harmonic lattice dynamics (HLD) calculations indicate that
+YCo$_5$ with 56 full valance electrons is dynamically unstable and this
+instability can be cured by reducing the number of electrons ($N_e$). Crystal
+orbital Hamilton population analysis reveals that the observed phonon
+instability originates from the large population of antibonding states near the
+Fermi level, which is dominated by the Co atoms in the honeycomb layer. The
+antibonding state depopulates with decreasing $N_e$, resulting in stable
+phonons for hole-doped YCo$_5$ with $N_e$ $\leq$ 55. We then evaluate the
+temperature-dependent MCA energy using both HLD and $ab$ $initio$ molecular
+dynamics (AIMD) methods. For the pristine YCo$_5$, we observe a very weak
+temperature decay of the MCA energy, indicating little effect of lattice
+dynamics. Also, the MCA energies evaluated with AIMD at all target temperatures
+are larger than that of the static hexagonal lattice at 0 K, which is mainly
+attributed to the structural distortion driven by soft phonon modes. In the
+hole-doped YCo$_5$, where the distortion is suppressed, a considerable
+temperature decay in MCA energy is obtained both in HLD and AIMD methods,
+showing that lattice dynamics effects on MCA energy are non-negligible.",2112.04124v1
+2023-02-14,A theoretical perspective on the modification of the magnetocrystalline anisotropy at molecule-cobalt interfaces,"We study the modification of the magnetocrystalline anisotropy (MCA) of Co
+slabs induced by several different conjugated molecular overlayers, i.e.,
+benzene, cyclooctatetraene, naphthalene, pyrene and coronene. We perform
+first-principles calculations based on Density Functional Theory and the
+magnetic force theorem. Our results indicate that molecular adsorption tends to
+favour a perpendicular MCA at surfaces. A detailed analysis of various
+atom-resolved quantities, accompanied by an elementary model, demonstrates that
+the underlying physical mechanism is related to the metal-molecule interfacial
+hybridization and, in particular, to the chemical bonding between the molecular
+C $p_z$ and the out-of-plane Co $d_{z^2}$ orbitals. This effect can be
+estimated from the orbital magnetic moment of the surface Co atoms, a
+microscopic observable accessible to both theory and experiments. As such, we
+suggest a way to directly assess the MCA modifications at molecule-decorated
+surfaces, overcoming the limitations of experimental studies that rely on fits
+of magnetization hysteresis loops. Finally, we also study the interface between
+Co and both C$_{60}$ and Alq$_3$, two molecules that find widespread use in
+organic spintronics. We show that the modification of the surface Co MCA is
+similar upon adsorption of these two molecules, thereby confirming the results
+of recent experiments.",2302.07330v1
+2013-12-13,Micromagnetics of shape anisotropy based permanent magnets,"In the search for rare-earth free permanent magnets, various ideas related to
+shape anisotropy are being pursued. In this work we assess the limits of shape
+contributions to the reversal stability using micromagnetic simulations. In a
+first series of tests we altered the aspect ratio of single phase prolate
+spheroids from 1 to 16. Starting with a sphere of radius $4.3$ times the
+exchange length $ L_{\mathrm{ex}}$ we kept the total magnetic volume constant
+as the aspect ratio was modified. For a ferromagnet with zero
+magnetocrystalline anisotropy the maximum coercive field reached up to $0.5$
+times the magnetization $M_{\mathrm{s}}$. Therefore, in materials with moderate
+uniaxial magnetocrystalline anisotropy, the addition of shape anisotropy could
+even double the coercive field. Interestingly due to non-uniform magnetization
+reversal there is no significant increase of the coercive field for an aspect
+ratio greater than 5. A similar limit of the maximum aspect ratio was observed
+in cylinders. The coercive field depends on the wire diameter. By decreasing
+the wire diameter from $8.7 L_{\mathrm{ex}}$ to $2.2 L_{\mathrm{ex}}$ the
+coercive field increased by 40%. In the cylinders nucleation of a reversed
+domain starts at the corners at the end. Smoothing the edges can improve the
+coercive field by about 10%.
+  In further simulations we compacted soft magnetic cylinders into a bulk-like
+arrangement. Misalignment and magnetostatic interactions cause a spread of $0.1
+M_{\mathrm{s}}$ in the switching fields of the rods. Comparing the volume
+averaged hysteresis loops computed for isolated rods and the hysteresis loop
+computed for interacting rods, we conclude that magnetostatic interactions
+reduce the coercive field by up to 20%.",1312.3791v3
+2008-09-24,The role of magnetic anisotropy in the Kondo effect,"In the Kondo effect, a localized magnetic moment is screened by forming a
+correlated electron system with the surrounding conduction electrons of a
+non-magnetic host. Spin S=1/2 Kondo systems have been investigated extensively
+in theory and experiments, but magnetic atoms often have a larger spin. Larger
+spins are subject to the influence of magnetocrystalline anisotropy, which
+describes the dependence of the magnetic moment's energy on the orientation of
+the spin relative to its surrounding atomic environment. Here we demonstrate
+the decisive role of magnetic anisotropy in the physics of Kondo screening. A
+scanning tunnelling microscope is used to simultaneously determine the
+magnitude of the spin, the magnetic anisotropy and the Kondo properties of
+individual magnetic atoms on a surface. We find that a Kondo resonance emerges
+for large-spin atoms only when the magnetic anisotropy creates degenerate
+ground-state levels that are connected by the spin flip of a screening
+electron. The magnetic anisotropy also determines how the Kondo resonance
+evolves in a magnetic field: the resonance peak splits at rates that are
+strongly direction dependent. These rates are well described by the energies of
+the underlying unscreened spin states.",0809.4289v1
+2019-02-28,Effect of atomic ordering on the magnetic anisotropy of single crystal Ni80Fe20,"We investigate the effect of atomic ordering on the magnetic anisotropy of
+Ni80Fe20 at.% (Py). To this end, Py films were grown epitaxially on MgO (001)
+using dc magnetron sputtering (dcMS) and high power impulse magnetron
+sputtering (HiPIMS). Aside from twin boundaries observed in the latter case,
+both methods present high quality single crystals with cube-on-cube epitaxial
+relationship as verified by the polar mapping of important crystal planes.
+However, X-ray diffraction results indicate higher order for the dcMS deposited
+film towards L12 Ni3Fe superlattice. This difference can be understood by the
+very high deposition rate of HiPIMS during each pulse which suppresses adatom
+mobility and ordering. We show that the dcMS deposited film presents biaxial
+anisotropy while HiPIMS deposition gives well defined uniaxial anisotropy.
+Thus, higher order achieved in the dcMS deposition behaves as predicted by
+magnetocrystalline anisotropy i.e. easy axis along the [111] direction that
+forced in the plane along the [110] direction due to shape anisotropy. The
+uniaxial behaviour in HiPIMS deposited film then can be explained by pair
+ordering or more recent localized composition non-uniformity theories. Further,
+we studied magnetoresistance of the films along the [100] directions using an
+extended van der Pauw method. We find that the electrical resistivities of the
+dcMS deposited film are lower than in their HiPIMS counterparts verifying the
+higher order in the dcMS case.",1903.00105v1
+2021-08-24,Shape anisotropy effect on magnetization reversal induced by linear down chirp pulse,"We investigate the influence of shape anisotropy on the magnetization
+reversal of a single-domain magnetic nanoparticle driven by a circularly
+polarized linear down-chirp microwave field pulse (DCMP). Based on the
+Landau-Lifshitz-Gilbert equation, numerical results show that the three
+controlling parameters of DCMP, namely, microwave amplitude, initial frequency
+and chirp rate, decrease with the increase of shape anisotropy. For certain
+shape anisotropy, the reversal time significantly reduces. These findings are
+related to the competition of shape anisotropy and uniaxial magnetocrystalline
+anisotropy and thus to the height of energy barrier which separates the two
+stable states. The result of damping dependence of magnetization reversal
+indicates that for a certain sample shape, there exists an optimal damping
+situation at which magnetization is fastest. Moreover, it is also shown that
+the required microwave field amplitude can be lowered by applying the
+spin-polarized current simultaneously. The usage of an optimum combination of
+both microwave field pulse and current is suggested to achieve cost efficiency
+and faster switching. So these findings may provide the knowledge to fabricate
+the shape of a single domain nanoparticle for the fast and power-efficient
+magnetic data storage device.",2108.10965v2
+2023-08-25,Thermal effect on microwave pulse driven magnetization switching of Stoner particle,"Recently it has been demonstrated that the cosine chirp microwave pulse
+(CCMP) is capable of achieving fast and energy-efficient magnetization-reversal
+of a nanoparticle with zero-Temperature. However, we investigate the finite
+temperature, $T$ effect on the CCMP-driven magnetization reversal using the
+framework of the stochastic Landau Lifshitz Gilbert equation. At finite
+Temperature, we obtain the CCMP-driven fast and energy-efficient reversal and
+hence estimate the maximal temperature, $T_{max}$ at which the magnetization
+reversal is valid. $T_{max}$ increases with increasing the nanoparticle
+cross-sectional area/shape anisotropy up to a certain value, and afterward
+$T_{max}$ decreases with the further increment of nanoparticle cross-sectional
+area/shape anisotropy. This is because of demagnetization/shape anisotropy
+field opposes the magnetocrystalline anisotropy, i.e., reduces the energy
+barrier which separates the two stable states. For smaller cross-sectional
+area/shape anisotropy, the controlling parameters of CCMP show decreasing trend
+with temperature. We also find that with the increment easy-plane
+shape-anisotropy, the required initial frequency of CCMP significantly reduces.
+For the larger volume of nanoparticles, the parameters of CCMP remains constant
+for a wide range of temperature which are desired for the device application.
+Therefore, The above findings might be useful to realize the CCMP-driven fast
+and energy-efficient magnetization reversal in realistic conditions.",2308.13124v1
+2007-02-23,"Evolution of the magnetic anisotropy with carrier density in hydrogenated (Ga,Mn)As","The magnetic properties of (Ga,Mn)As thin films depend on both the Mn doping
+level and the carrier concentration. Using a post growth hydrogenation process
+we show that it is possible to decrease the hole density from 1.1021 cm-3 to
+<1017 cm-3 while maintaining the manganese concentration constant. For such a
+series of films we have investigated the variation of the magnetization, the
+easy and hard axes of magnetization, the critical temperatures, the coercive
+fields and the magnetocrystalline anisotropy constants as a function of
+temperature using magnetometry, ferromagnetic resonance and magneto-transport
+measurements. In particular, we evidenced that magnetic easy axes flipped from
+out-of-plane [001] to in-plane [100] axis, followed by the <110> axes, with
+increasing hole density and temperature. Our study concluded on a general
+agreement with mean-field theory predictions of the expected easy axis
+reversals, and of the weight of uniaxial and cubic anisotropies in this
+material.",0702548v1
+2008-12-19,Domain structure of epitaxial Co films with perpendicular anisotropy,"Epitaxial hcp Cobalt films with pronounced c-axis texture have been prepared
+by pulsed lased deposition (PLD) either directly onto Al2O3 (0001) single
+crystal substrates or with an intermediate Ruthenium buffer layer. The crystal
+structure and epitaxial growth relation was studied by XRD, pole figure
+measurements and reciprocal space mapping. Detailed VSM analysis shows that the
+perpendicular anisotropy of these highly textured Co films reaches the
+magnetocrystalline anisotropy of hcp-Co single crystal material. Films were
+prepared with thickness t of 20 nm < t < 100 nm to study the crossover from
+in-plane magnetization to out-of-plane magnetization in detail. The analysis of
+the periodic domain pattern observed by magnetic force microscopy allows to
+determine the critical minimum thickness below which the domains adopt a pure
+in-plane orientation. Above the critical thickness the width of the stripe
+domains is evaluated as a function of the film thickness and compared with
+domain theory. Especially the discrepancies at smallest film thicknesses show
+that the system is in an intermediate state between in-plane and out-of-plane
+domains, which is not described by existing analytical domain models.",0812.3797v1
+2011-03-28,The effect of chemical disorder on the magnetic anisotropy of strained Fe-Co films,"Strained Fe-Co films have recently been demonstrated to exhibit a large
+magnetocrystalline anisotropy (MCA) and thus to be of potential interest as
+magnetic storage material. Here, we show by means of density-functional (DF)
+calculations, that chemical order can remarkably enhance the MCA. We also
+investigate the effect of relaxation perpendicular to the applied strain and
+evaluate the strain energy as a function of Co concentration and substrate
+lattice parameter. On this basis, favourable preparation routes for films with
+a large perpendicular anisotropy are suggested.",1103.5303v1
+2013-03-21,"Co monolayers and adatoms on Pd(100), Pd(111) and Pd(110): Anisotropy of magnetic properties","We investigate to what extent the magnetic properties of deposited
+nanostructures can be influenced by selecting as a support different surfaces
+of the same substrate material. Fully relativistic ab initio calculations were
+performed for Co monolayers and adatoms on Pd(100), Pd(111), and Pd(110)
+surfaces. Changing the crystallographic orientation of the surface has a
+moderate effect on the spin magnetic moment and on the number of holes in the d
+band, a larger effect on the orbital magnetic moment but sometimes a dramatic
+effect on the magnetocrystalline anisotropy energy (MAE) and on the magnetic
+dipole term T_alpha. The dependence of T_alpha on the magnetization direction
+alpha can lead to a strong apparent anisotropy of the spin magnetic moment as
+deduced from the X-ray magnetic circular dichroism (XMCD) sum rules. For
+systems in which the spin-orbit coupling is not very strong, the T_alpha term
+can be understood as arising from the differences between components of the
+spin magnetic moment associated with different magnetic quantum numbers m.",1303.5262v1
+2014-03-20,Magnetization of densely packed interacting magnetic nanoparticles with cubic and uniaxial anisotropies: A Monte Carlo study,"The magnetization curves of densely packed single domain magnetic
+nanoparticles (MNP) are investigated by Monte Carlo simulations in the
+framework of an effective one spin model. The particles whose size
+polydispersity is taken into account are arranged in spherical clusters and
+both dipole dipole interactions (DDI) and magnetic anisotropy energy (MAE) are
+included in the total energy. Having in mind the special case of spinel
+ferrites of intrinsic cubic symmetry, combined cubic and uniaxial
+magnetocrystalline anisotropies are considered with different configurations
+for the orientations of the cubic and uniaxial axes. It is found that the DDI,
+together with a marked reduction of the linear susceptibility are responsible
+for a damping of the peculiarities due to the MAE cubic component on the
+magnetization. As an application, we show that the simulated magnetization
+curves compare well to experimental results for $\gamma$--Fe$_2$O$_3$ MNP for
+small to moderate values of the field.",1403.5157v1
+2014-07-22,Out- versus in-plane magnetic anisotropy of free Fe and Co nanocrystals: tight-binding and first-principles studies,"We report tight-binding (TB) and Density Function Theory (DFT) calculations
+of magnetocrystalline anisotropy energy (MAE) of free Fe (body centerd cubic)
+and Co (face centered cubic) slabs and nanocrystals. The nanocrystals are
+truncated square pyramids which can be obtained experimentally by deposition of
+metal on a SrTiO$_3$(001) substrate. For both elements our local analysis shows
+that the total MAE of the nanocrystals is largely dominated by the contribution
+of (001) facets. However, while the easy axis of Fe(001) is out-of-plane, it is
+in-plane for Co(001). This has direct consequences on the magnetic reversal
+mechanism of the nanocrystals. Indeed, the very high uniaxial anisotropy of Fe
+nanocrystals makes them a much better potential candidate for magnetic storage
+devices.",1407.5830v1
+2014-09-19,"Magnetic anisotropy of Fe_1-yX_yPt-L10 [X=Cr,Mn,Co,Ni,Cu] bulk alloys","We demonstrate by means of fully relativistic first principles calculations
+that, by substitution of Fe by Cr, Mn, Co, Ni or Cu in FePt-L10 bulk alloys,
+with fixed Pt content, it is possible to tune the magnetocrystalline anisotropy
+energy by adjusting the content of the non-magnetic species in the material.
+The changes in the geometry due to the inclusion of each element induces
+different values of the tetragonality and hence changes in the magnetic
+anisotropy and in the net magnetic moment. The site resolved magnetic moments
+of Fe increase with the X content whilst those of Pt and X are simultaneously
+reduced. The calculations are in good quantitative agreement with experimental
+data and demonstrate that models with fixed band structure but varying numbers
+of electrons per unit cell are insufficient to describe the experimental data
+for doped FePt-L10 alloys.",1409.5806v1
+2015-04-21,Anisotropic interactions opposing magnetocrystalline anisotropy in Sr$_3$NiIrO$_6$,"We report our investigation of the electronic and magnetic excitations of
+Sr$_3$NiIrO$_6$ by resonant inelastic x-ray scattering at the Ir L$_3$ edge.
+The intra-$t_{2g}$ electronic transitions are analyzed using an atomic model,
+including spin-orbit coupling and trigonal distortion of the IrO$_6$
+octahedron, confronted to {\it ab initio} quantum chemistry calculations. The
+Ir spin-orbital entanglement is quantified and its implication on the magnetic
+properties, in particular in inducing highly anisotropic magnetic interactions,
+is highlighted. These are included in the spin-wave model proposed to account
+for the dispersionless magnetic excitation that we observe at 90 meV. By
+counterbalancing the strong Ni$^{2+}$ easy-plane anisotropy that manifests
+itself at high temperature, the anisotropy of the interactions finally leads to
+the remarkable easy-axis magnetism reported in this material at low
+temperature.",1504.05420v2
+2016-10-11,Large magnetic anisotropy predicted for rare-earth free Fe16-xCoxN2 alloys,"Structures and magnetic properties of Fe16-xCoxN2 are studied using adaptive
+genetic algorithm and first-principles calculations. We show that substituting
+Fe by Co in Fe16N2 with Co/Fe ratio smaller than 1 can greatly improve the
+magnetic anisotropy of the material. The magnetocrystalline anisotropy energy
+from first-principles calculations reaches 3.18 MJ/m3 (245.6 {\mu}eV per metal
+atom) for Fe12Co4N2, much larger than that of Fe16N2 and is one of the largest
+among the reported rare-earth free magnets. From our systematic crystal
+structure searches, we show that there is a structure transition from
+tetragonal Fe16N2 to cubic Co16N2 in Fe16-xCoxN2 as the Co concentration
+increases, which can be well explained by electron counting analysis. Different
+magnetic properties between the Fe-rich (x < 8) and Co-rich (x > 8) Fe16-xCoxN2
+is closely related to the structural transition.",1610.03544v1
+2017-10-04,Ferromagnetic order in dipolar systems with anisotropy: application to magnetic nanoparticle supracrystals,"Single domain magnetic nanoparticles (MNP) interacting through dipolar
+interactions (DDI) in addition to the magnetocrystalline energy may present a
+low temperature ferromagnetic (SFM) or spin glass (SSG) phase according to the
+underlying structure and the degree of order of the assembly. We study, from
+Monte Carlo simulations in the framework of the effective one-spin or macrospin
+models, the case of a monodisperse assembly of single domain MNP fixed on the
+sites of a perfect lattice with fcc symmetry and randomly distributed easy
+axes. We limit ourselves to the case of a low anisotropy, namely the onset of
+the disappearance of the dipolar long-range ferromagnetic (FM) phase obtained
+in the absence of anisotropy due to the disorder introduced by the latter.",1710.01532v2
+2018-02-26,Multiferroic Micro-Motors with Deterministic Single Input Control,"This paper describes a method for achieving continuous deterministic
+360$^{\circ} $ magnetic moment rotations in single domain magnetoelastic discs,
+and examines the performance bounds for a mechanically lossless multiferroic
+bead-on-a-disc motor based on dipole coupling these discs to small magnetic
+nanobeads. The continuous magnetic rotations are attained by controlling the
+relative orientation of a four-fold anisotropy (e.g., cubic magnetocrystalline
+anisotropy) with respect to the two-fold magnetoelastic anisotropy. This
+approach produces continuous rotations from the quasi-static regime up through
+operational frequencies of several GHz. Driving strains of only $\approx$90 to
+180 ppm are required for operation of motors using existing materials. The
+large operational frequencies and small sizes, with lateral dimensions of
+$\approx$100s of nanometers, produce large power densities for the rotary
+bead-on-a-disc motor, and a newly proposed linear variant, in a size range
+where power dense alternative technologies do not currently exist.",1802.09420v1
+2018-10-02,Magnetocrystalline anisotropy and exchange probed by high-field anomalous Hall effect in fully-compensated half-metallic Mn2RuxGa thin films,"Magnetotransport is investigated in thin films of the half-metallic
+ferrimagnet Mn$_2$Ru$_x$Ga in pulsed magnetic fields of up to 58 T. A
+non-vanishing Hall signal is observed over a broad temperature range, spanning
+the compensation temperature 155 K, where the net magnetic moment is strictly
+zero, the anomalous Hall conductivity is 6673 $\Omega^{-1}.m^{-1}$ and the
+coercivity exceeds 9 T. Molecular field modelling is used to determine the
+intra- and inter-sublattice exchange constants and from the spin-flop
+transition we infer the anisotropy of the electrically active sublattice to be
+216 kJ/m$^3$ and predict the magnetic resonances frequencies. Exchange and
+anisotropy are comparable and hard-axis applied magnetic fields result in a
+tilting of the magnetic moments from their collinear ground state. Our analysis
+is applicable to collinear ferrimagnetic half-metal systems.",1810.01158v1
+2019-04-08,Magnetic anisotropy and entropy change in trigonal Cr$_{0.62}$Te,"We present a comprehensive investigation on anisotropic magnetic and
+magnetocaloric properties of the quasi-two-dimensional weak itinerant
+ferromagnet trigonal Cr$_{0.62}$Te single crystals. Magnetic-anisotropy-induced
+satellite transition $T^*$ is observed at low fields applied parallel to the
+$ab$ plane below $T_c$. The $T^*$ is featured by an anomalous magnetization
+downturn, similar to that in structurally related CrI$_3$, and shows a
+monotonous shift towards lower temperature with increasing field.
+Magnetocrystalline anisotropy is also reflected in magnetic entropy change
+$\Delta S_M(T,H)$ and relative cooling power RCP. Given the high $T_c$,
+Cr$_{0.62}$Te crystals are materials of interest for nanofabrication in basic
+science and applied technology.",1904.04247v3
+2019-06-26,Concentration tuned tetragonal strain in alloys: application to magnetic anisotropy of FeNi$_{1-x}$Co$_x$,"We explore an opportunity to induce and control tetragonal distortion in
+materials. The idea involves formation of a binary alloy from parent compounds
+having body-centered and face-centered symmetries. The concept is illustrated
+in the case of FeNi$_{1-x}$Co$_x$ magnetic alloy formed by substitutional
+doping of the L1$_0$ FeNi magnet with Co. Using electronic structure
+calculations we demonstrate that the tetragonal strain in this system can be
+controlled by concentration and it reaches maximum for $x=0.5$. This finding is
+then applied to create a large magnetocrystalline anisotropy (MAE) in
+FeNi$_{1-x}$Co$_x$ system by considering an interplay of the tetragonal
+distortion with electronic concentration and chemical anisotropy. In
+particular, we identify a new ordered FeNi$_{0.5}$Co$_{0.5}$ system with MAE
+larger by a factor 4.5 from the L1$_0$ FeNi magnet.",1906.11329v1
+2020-06-03,Superconductivity-induced change in magnetic anisotropy in epitaxial ferromagnet-superconductor hybrids with spin-orbit interaction,"The interaction between superconductivity and ferromagnetism in thin film
+superconductor/ferromagnet heterostructures is usually reflected by a change in
+superconductivity of the S layer set by the magnetic state of the F layers.
+Here we report the converse effect: transformation of the magnetocrystalline
+anisotropy of a single Fe(001) layer, and thus its preferred magnetization
+orientation, driven by the superconductivity of an underlying V layer through a
+spin-orbit coupled MgO interface. We attribute this to an additional
+contribution to the free energy of the ferromagnet arising from the controlled
+generation of triplet Cooper pairs, which depends on the relative angle between
+the exchange field of the ferromagnet and the spin-orbit field. This is
+fundamentally different from the commonly observed magnetic domain modification
+by Meissner screening or domain wall-vortex interaction and offers the ability
+to fundamentally tune magnetic anisotropies using superconductivity - a key
+step in designing future cryogenic magnetic memories.",2006.02118v2
+2020-11-11,Characterization of room-temperature in-plane magnetization in thin flakes of CrTe$_2$ with a single spin magnetometer,"We demonstrate room-temperature ferromagnetism with in-plane magnetic
+anisotropy in thin flakes of the CrTe$_2$ van der Waals ferromagnet. Using
+quantitative magnetic imaging with a single spin magnetometer based on a
+nitrogen-vacancy defect in diamond, we infer a room-temperature in-plane
+magnetization in the range of $M\sim 27$ kA/m for flakes with thicknesses down
+to $20$ nm. In addition, our measurements indicate that the orientation of the
+magnetization is not determined solely by shape anisotropy in micron-sized
+CrTe$_2$ flakes, which suggest the existence of a non-negligible
+magnetocrystalline anisotropy. These results make CrTe$_2$ a unique system in
+the growing family of van der Waals ferromagnets, as it is the only material
+platform known to date which offers an intrinsic in-plane magnetization and a
+Curie temperature above $300$ K in thin flakes.",2011.05722v2
+2021-09-14,Valence state determines the band magnetocrystalline anisotropy in 2D rare-earth/noble-metal compounds,"In intermetallic compounds with zero-orbital momentum ($L=0$) the magnetic
+anisotropy and the electronic band structure are interconnected. Here, we
+investigate this connection on divalent Eu and trivalent Gd intermetallic
+compounds. We find by X-ray magnetic circular dichroism an out-of-plane easy
+magetization axis in 2D atom-thick EuAu$_2$. Angle-resolved photoemission and
+density-functional theory prove that this is due to strong $f-d$ band
+hybridization and Eu$^{2+}$ valence. In contrast, the easy in-plane
+magnetization of the structurally-equivalent GdAu$_2$ is ruled by
+spin-orbit-split $d$-bands, notably Weyl nodal lines, occupied in the Gd$^{3+}$
+state. Regardless of the $L$ value, we predict a similar itinerant electron
+contribution to the anisotropy of analogous compounds.",2109.06769v2
+2022-10-21,A possible electronic state quasi-half-valley-metal in $\mathrm{VGe_2P_4}$ monolayer,"One of the key problems in valleytronics is to realize valley polarization.
+Ferrovalley (FV) semiconductor and half-valley-metal (HVM) have been proposed,
+which possess intrinsic spontaneous valley polarization. Here, we propose the
+concept of quasi-half-valley-metal (QHVM), including electron and hole carriers
+with only a type of carriers being valley polarized. The QHVM may realize
+separation function of electron and hole. A concrete example of
+$\mathrm{VGe_2P_4}$ monolayer is used to illustrate our proposal through the
+first-principle calculations. To better realize QHVM, the electric field is
+applied to tune related valley properties of $\mathrm{VGe_2P_4}$. Within
+considered electric field range, $\mathrm{VGe_2P_4}$ is always ferromagnetic
+(FM) ground state, which possesses out-of-plane magnetization by calculating
+magnetic anisotropy energy (MAE) including magnetic shape anisotropy (MSA) and
+magnetocrystalline anisotropy (MCA) energies. These out-of-plane FM properties
+guarantee intrinsic spontaneous valley polarization in $\mathrm{VGe_2P_4}$.
+Within a certain range of electric field, the QHVM can be maintained, and the
+related polarization properties can be effectively tuned. Our works pave the
+way toward two-dimensional (2D) functional materials design of valleytronics.",2210.11827v1
+2023-07-24,In-plane magnetocrystalline anisotropy in the van der Waals antiferromagnet FePSe$_3$ probed by magneto-Raman scattering,"Magnon gap excitations selectively coupled to phonon modes have been studied
+in FePSe$_3$ layered antiferromagnet with magneto-Raman scattering experiments
+performed at different temperatures. The bare magnon excitation in this
+material has been found to be split (by $\approx~1.2$ cm$^{-1}$) into two
+components each being selectively coupled to one of the two degenerated, nearby
+phonon modes. Lifting the degeneracy of the fundamental magnon mode points out
+toward the biaxial character of the FePS$_3$ antiferromagnet, with an
+additional in-plane anisotropy complementing much stronger, out-of-plane
+anisotropy. Moreover, the tunability, with temperature, of the phonon- versus
+the magnon-like character of the observed coupled modes has been demonstrated.",2307.12692v1
+2023-12-05,Iron and gold thin films: first-principles study,"Using density functional theory, we carried out systematic calculations for a
+series of ultrathin iron layers with thicknesses ranging from one atomic
+monolayer to eleven monolayers (up to about 1.5 nm). We considered three cases:
+(1) iron layers both on a gold substrate and coated with gold, (2) iron layers
+on a gold substrate but without coverage, and (3) freestanding iron layers
+adjacent to a vacuum. For our models, we chose initial bcc Fe(001) surfaces and
+fcc Au(001) substrates. Based on the calculations, we determined the details of
+the geometry and magnetic properties of the systems. We calculate lattice
+parameters, magnetic moments, Curie temperatures and magnetocrystalline
+anisotropy energies. From the thickness dependence, we determined the volume
+and surface contributions to the magnetic anisotropy constant. The further
+analysis allowed us to determine the thickness ranges of the occurrence of
+perpendicular magnetic anisotropy, as well as the effect of thickness and the
+presence of a substrate and cap layer on the direction of the magnetization
+easy axis.",2312.02701v1
+2020-12-09,Pressure control of the magnetic anisotropy of the quasi-two-dimensional van der Waals ferromagnet Cr$_2$Ge$_2$Te$_6$,"We report the results of the pressure-dependent measurements of the static
+magnetization and of the ferromagnetic resonance (FMR) of Cr$_2$Ge$_2$Te$_6$ to
+address the properties of the ferromagnetic phase of this quasi-two-dimensional
+van der Waals magnet. The static magnetic data at hydrostatic pressures up to
+3.4 GPa reveal a gradual suppression of ferromagnetism in terms of a reduction
+of the critical transition temperature, a broadening of the transition width
+and an increase of the field necessary to fully saturate the magnetization
+$M_{\rm s}$. The value of $M_{\rm s} \simeq 3\mu_{\rm B}$/Cr remains constant
+within the error bars up to a pressure of 2.8 GPa. The anisotropy of the FMR
+signal continuously diminishes in the studied hydrostatic pressure range up to
+2.39 GPa suggesting a reduction of the easy-axis type magnetocrystalline
+anisotropy energy (MAE). A quantitative analysis of the FMR data gives evidence
+that up to this pressure the MAE constant $K_{\rm U}$, although getting
+significantly smaller, still remains finite and positive, i.e. of the easy-axis
+type. Therefore, a recently discussed possibility of switching the sign of the
+magnetocrystalline anisotropy in Cr$_2$Ge$_2$Te$_6$ could only be expected at
+still higher pressures, if possible at all due to the observed weakening of the
+ferromagnetism under pressure. This circumstance may be of relevance for the
+design of strain-engineered functional heterostructures containing layers of
+Cr$_2$Ge$_2$Te$_6$.",2012.05193v2
+2021-02-02,"On the relationship between orbital moment anisotropy, magnetocrystalline anisotropy, and Dzyaloshinskii-Moriya interaction in W/Co/Pt trilayers","We have studied the Co layer thickness dependences of magnetocrystalline
+anisotropy (MCA), Dzyaloshinskii-Moriya interaction (DMI), and orbital moment
+anisotropy (OMA) in W/Co/Pt trilayers, in order to clarify their correlations
+with each other. We find that the MCA favors magnetization along the film
+normal and monotonically increases with decreasing effective magnetic layer
+thickness ($t_\mathrm{eff}$). The magnitude of the Dzyaloshinskii-Moriya
+exchange constant ($|D|$) increases with decreasing $t_\mathrm{eff}$ until
+$t_\mathrm{eff} \sim$1 nm, below which $|D|$ decreases. The MCA and $|D|$ scale
+with $1/t_\mathrm{eff}$ for $t_\mathrm{eff}$ larger than $\sim$1 nm, indicating
+an interfacial origin. The increase of MCA with decreasing $t_\mathrm{eff}$
+continues below $t_\mathrm{eff}$ $\sim$ 1 nm, but with a slower rate. To
+clarify the cause of the $t_\mathrm{eff}$ dependences of MCA and DMI, the OMA
+of Co in W/Co/Pt trilayers is studied using x-ray magnetic circular dichroism
+(XMCD). We find non-zero OMA when $t_\mathrm{eff}$ is smaller than $\sim$0.8
+nm. The OMA increases with decreasing $t_\mathrm{eff}$ more rapidly than what
+is expected from the MCA, indicating that factors other than OMA contribute to
+the MCA at small $t_\mathrm{eff}$. The $t_\mathrm{eff}$ dependence of the OMA
+also suggests that $|D|$ at $t_\mathrm{eff}$ smaller than $\sim$1 nm is not
+related to the OMA at the interface. We propose that the growth of Co on W
+results in a strain and/or texture that reduces the interfacial DMI, and, to
+some extent, MCA at small $t_\mathrm{eff}$.",2102.01283v2
+2021-08-26,Magnetoelastic anisotropy in Heusler-type Mn$_{2-δ}$CoGa$_{1+δ}$ films,"Perpendicular magnetization is essential for high-density memory application
+using magnetic materials. High-spin polarization of conduction electrons is
+also required for realizing large electric signals from spin-dependent
+transport phenomena. Heusler alloy is a well-known material class showing the
+half-metallic electronic structure. However, its cubic lattice nature favors
+in-plane magnetization and thus minimizes the perpendicular magnetic anisotropy
+(PMA), in general. This study focuses on an inverse-type Heusler alloy,
+Mn$_{2-\delta}$CoGa$_{1+\delta}$ (MCG) with a small off-stoichiometry
+($\delta$) , which is expected to be a half-metallic material. We observed
+relatively large uniaxial magnetocrystalline anisotropy constant
+($K_\mathrm{u}$) of the order of 10$^5$ J/m$^3$ at room temperature in MCG
+films with a small tetragonal distortion of a few percent. A positive
+correlation was confirmed between the $c/a$ ratio of lattice constants and
+$K_\mathrm{u}$. Imaging of magnetic domains using Kerr microscopy clearly
+demonstrated a change in the domain patterns along with $K_\mathrm{u}$. X-ray
+magnetic circular dichroism (XMCD) was employed using synchrotron radiation
+soft x-ray beam to get insight into the origin for PMA. Negligible angular
+variation of orbital magnetic moment ($\Delta m_\mathrm{orb}$) evaluated using
+the XMCD spectra suggested a minor role of the so-called Bruno's term to
+$K_\mathrm{u}$. Our first principles calculation reasonably explained the small
+$\Delta m_\mathrm{orb}$ and the positive correlation between the $c/a$ ratio
+and $K_\mathrm{u}$. The origin of the magnetocrystalline anisotropy was
+discussed based on the second-order perturbation theory in terms of the
+spin--orbit coupling, claiming that the mixing of the occupied $\uparrow$- and
+the unoccupied $\downarrow$-spin states is responsible for the PMA of the MCG
+films.",2108.11547v2
+2013-10-23,Magnetoelastic coupling induced magnetic anisotropy in Co$_2$(Fe/Mn)Si thin films,"The influence of epitaxial strain on uniaxial magnetic anisotropy of
+Co$_{2}$FeSi (CFS) and Co$_{2}$MnSi (CMS) Heusler alloy thin films grown on
+(001) SrTiO$_3$ (STO) and MgO is reported. The in-plane biaxial strain is
+susceptible to tune by varying the thickness of the films on STO, while on MgO
+the films show in-plane easy axis for magnetization (\overrightarrow{M})
+irrespective of their thickness. A variational analysis of magnetic free energy
+functional within the Stoner-Wohlfarth coherent rotation model with
+out-of-plane uniaxial anisotropy for the films on STO showed the presence of
+magnetoelastic anisotropy with magnetostriction constant $\approx$
+(12.22$\pm$0.07)$\times 10^{-6}$ and (2.02$\pm$0.06)$\times 10^{-6}$, in
+addition to intrinsic magnetocrystalline anisotropy $\approx$ -1.72$\times
+10^{6}$ erg/cm$^{3}$ and -3.94$\times 10^{6}$ erg/cm$^{3}$ for CFS and CMS,
+respectively. The single-domain phase diagram reveals a gradual transition from
+in-plane to out-of-plane orientation of magnetization with the decreasing film
+thickness. A maximum canting angle of 41.5$^{\circ}$ with respect to film plane
+is predicted for the magnetization of the thinnest (12 nm) CFS film on STO. The
+distinct behaviour of \overrightarrow{M} in the films with lower thickness on
+STO is attributed to strain-induced tetragonal distortion.",1310.6204v1
+2016-10-02,"Intrinsic magnetic properties of {$R$(Fe$_{1-x}$Co$_{x}$)$_{11}$Ti$Z$} ($R$ = Y and Ce; $Z$ = H, C, and N)","To guide improved properties coincident with reduction of critical materials
+in permanent magnets, we investigate via density functional theory (DFT) the
+intrinsic magnetic properties of a promising system,
+$R$(Fe$_{1-x}$Co$_{x}$)$_{11}$Ti$Z$ with $R$=Y, Ce and interstitial doping
+($Z$=H, C, N). The magnetization $M$, Curie temperature $T_\text{C}$, and
+magnetocrystalline anisotropy energy $K$ calculated in local density
+approximation to DFT agree well with measurements. Site-resolved contributions
+to $K$ reveal that all three Fe sublattices promote uniaxial anisotropy in
+YFe$_{11}$Ti, while competing anisotropy contributions exist in YCo$_{11}$Ti.
+As observed in experiments on $R$(Fe$_{1-x}$Co$_{x}$)$_{11}$Ti, we find a
+complex nonmonotonic dependence of $K$ on Co content, and show that anisotropy
+variations are a collective effect of MAE contributions from all sites and
+cannot be solely explained by preferential site occupancy. With interstitial
+doping, calculated $T_\text{C}$ enhancements are in the sequence of N$>$C$>$H,
+with volume and chemical effects contributing to the enhancement. The uniaxial
+anisotropy of $R$(Fe$_{1-x}$Co$_{x}$)$_{11}$Ti$Z$ generally decreases with C
+and N; although, for $R$=Ce, C doping is found to greatly enhance it for a
+small range of 0.7$<$$x$$<$0.9.",1610.00365v1
+2020-05-29,Electron spin resonance and ferromagnetic resonance spectroscopy in the high-field phase of the van der Waals magnet CrCl$_3$,"We report a comprehensive high-field/high-frequency electron spin resonance
+(ESR) study on single crystals of the van der Waals magnet CrCl$_3$. This
+material, although being known for quite a while, has received recent
+significant attention in a context of the use of van der Waals magnets in novel
+spintronic devices. Temperature-dependent measurements of the resonance fields
+were performed between 4 and 175 K and with the external magnetic field applied
+parallel and perpendicular to the honeycomb planes of the crystal structure.
+These investigations reveal that the resonance line shifts from the
+paramagnetic resonance position already at temperatures well above the
+transition into a magnetically ordered state. Thereby the existence of
+ferromagnetic short-range correlations above the transition is established and
+the intrinsically two-dimensional nature of the magnetism in the title compound
+is proven. To study details of the magnetic anisotropies in the field-induced
+effectively ferromagnetic state at low temperatures, frequency-dependent
+ferromagnetic resonance (FMR) measurements were conducted at 4 K. The observed
+anisotropy between the two magnetic-field orientations is analyzed by means of
+numerical simulations based on a phenomenological theory of FMR. These
+simulations are in excellent agreement with measured data if the shape
+anisotropy of the studied crystal is taken into account, while the
+magnetocrystalline anisotropy is found to be negligible in CrCl$_3$. The
+absence of a significant intrinsic anisotropy thus renders this material as a
+practically ideal isotropic Heisenberg magnet.",2005.14559v1
+2022-07-27,Importance of magnetic shape anisotropy in determining magnetic and electronic properties of monolayer $\mathrm{VSi_2P_4}$,"Two-dimensional (2D) ferromagnets have been a fascinating subject of
+research, and magnetic anisotropy (MA) is indispensable for stabilizing the 2D
+magnetic order. Here, we investigate magnetic anisotropy energy (MAE), magnetic
+and electronic properties of $\mathrm{VSi_2P_4}$ by using the generalized
+gradient approximation plus $U$ (GGA+$U$) approach. For large $U$, the magnetic
+shape anisotropy (MSA) energy has a more pronounced contribution to the MAE,
+which can overcome the magnetocrystalline anisotropy (MCA) energy to evince an
+easy-plane. For fixed out-of-plane MA, monolayer $\mathrm{VSi_2P_4}$ undergoes
+ferrovalley (FV), half-valley-metal (HVM), valley-polarized quantum anomalous
+Hall insulator (VQAHI), HVM and FV states with increasing $U$. However, for
+assumptive in-plane MA, there is no special quantum anomalous Hall (QAH) state
+and spontaneous valley polarization within considered $U$ range. According to
+the MAE and electronic structure with fixed out-of-plane or in-plane MA, the
+intrinsic phase diagram shows common magnetic semiconductor (CMS), FV and VQAHI
+in monolayer $\mathrm{VSi_2P_4}$. At representative $U$$=$3 eV widely used in
+references, $\mathrm{VSi_2P_4}$ can be regarded as a 2D-$XY$ magnet, not
+Ising-like 2D long-range order magnets predicted in previous works with only
+considering MCA energy. Our findings shed light on importance of MSA in
+determining magnetic and electronic properties of monolayer
+$\mathrm{VSi_2P_4}$.",2207.13420v1
+2022-12-15,Exploration of all-3d Heusler alloys for permanent magnets: an ab initio based high-throughput study,"Heusler alloys have attracted interest in various fields of functional
+materials since their properties can quite easily be tuned by composition.
+Here, we have investigated the relatively new class of all-3d Heusler alloys in
+view of its potential as permanent magnets. To identify suitable candidates, we
+performed a high-throughput study using an electronic structure database to
+search for X$_2$YZ-type Heusler systems with tetragonal symmetry and high
+magnetization. For the alloys which passed our selection filters, we have used
+a combination of density functional theory calculations and spin dynamics
+modelling to investigate their magnetic properties including the
+magnetocrystalline anisotropy energy and exchange interactions. The candidates
+which fulfilled all the search criteria served as input for the investigation
+of the temperature dependence of the magnetization and determination of Curie
+temperature. Based on our results, we suggest that Fe$_2$NiZn, Fe$_2$NiTi and
+Ni$_2$CoFe are potential candidates for permanent magnets with large
+out-of-plane magnetic anisotropy (1.23, 0.97 and 0.82 MJ/m$^3$ respectively)
+and high Curie temperatures lying more than 200 K above the room temperature.
+We further show that the magnitude and direction of anisotropy is very
+sensitive to the strain by calculating the values of anisotropy energy for
+several tetragonal phases. Thus, application of strain can be used to tune the
+anisotropy in these compounds.",2212.07845v3
+2023-02-06,Large ordered moment with strong easy-plane anisotropy and vortex-domain pattern in the kagome ferromagnet Fe$_3$Sn,"We report the structural and magnetic properties of high-quality bulk single
+crystals of the kagome ferromagnet Fe$_3$Sn. The dependence of magnetisation on
+the magnitude and orientation of the external field reveals strong easy-plane
+type uniaxial magnetic anisotropy, which shows a monotonous increase from
+$K_1=-0.99\times 10^6 J/m^3$ at 300\,K to $-1.23\times10^6 J/m^3$ at 2\,K. Our
+\textit{ab initio} electronic structure calculations yield the value of total
+magnetic moment of about 6.9 $\mu_B$/f.u. and a magnetocrystalline anisotropy
+energy density of 0.406\,meV/f.u. ($1.16\times10^6 J/m^3$) both being in good
+agreement with the experimental values. The self-consistent DFT computations
+for the components of the spin/orbital moments indicate that the small
+difference between the saturation magnetisations measured along and
+perpendicular to the kagome layers results from the subtle balance between the
+Fe and Sn spin/orbital moments on the different sites. In zero field, magnetic
+force microscopy reveals micrometer-scale magnetic vortices with weakly pinned
+cores that vanish at $\sim$3\,T applied perpendicular to the kagome plane. Our
+micromagnetic simulations, using the experimentally determined value of
+anisotropy, well reproduce the observed vortex-domain structure. The present
+study, in comparison with the easy-axis ferromagnet Fe$_3$Sn$_2$, shows that
+varying the stacking of kagome layers provides an efficient control over
+magnetic anisotropy in this family of Fe-based kagome magnets.",2302.13810v1
+2024-01-04,Anisotropy of the anomalous Hall effect in the altermagnet candidate Mn$_5$Si$_3$ films,"Altermagnets are compensated magnets belonging to spin symmetry groups that
+allow alternating spin polarizations both in the coordinate space of the
+crystal and in the momentum space of the electronic structure. In these
+materials the anisotropic local crystal environment of the different
+sublattices lowers the symmetry of the system so that the opposite-spin
+sublattices are connected only by rotations, which results in an unconventional
+spin-polarized band structure in the momentum space. This low symmetry of the
+crystal structure is expected to be reflected in the anisotropy of the
+anomalous Hall effect. In this work, we study the anisotropy of the anomalous
+Hall effect in epitaxial thin films of Mn$_5$Si$_3$, an altermagnetic candidate
+material. We first demonstrate a change in the relative N\'eel vector
+orientation when rotating the external field orientation through systematic
+changes in both the anomalous Hall effect and the anisotropic longitudinal
+magnetoresistance. We then show that the anomalous Hall effect in this material
+is anisotropic with the N\'eel vector orientation relative to the crystal
+structure and that this anisotropy requires high crystal quality and unlikely
+correlates with the magnetocrystalline anisotropy. Our results provide further
+systematic support to the case for considering epitaxial thin films of
+Mn$_5$Si$_3$ as an altermagnetic candidate material.",2401.02275v1
+2015-02-18,"Magnetocrystalline anisotropic effect in GdCo$_{1-x}$Fe$_x$AsO ($x = 0, 0.05$)","From a systematic study of the electrical resistivity $\rho(T,H)$, magnetic
+susceptibility $\chi(T,H)$, isothermal magnetization $M(H)$ and the specific
+heat $C(T,H)$, a temperature-magnetic field ($T$-$H$) phase diagram has been
+established for GdCo$_{1-x}$Fe$_x$AsO ($x = 0$ and $0.05$) polycrystalline
+compounds. GdCoAsO undergoes two long-range magnetic transitions: ferromagnetic
+(FM) transition of Co $3d$ electrons ($T_\textup{C}^\textup{Co}$) and
+antiferromagnetic (AFM) transition of Gd $4f$ electrons
+($T_\textup{N}^\textup{Gd}$). For the Fe-doped sample ($x=0.05$), an extra
+magnetic reorientation transition takes place below $T_\textup{N}^\textup{Gd}$,
+which is likely associated with Co moments. The two magnetic species of Gd and
+Co are coupled antiferromagnetically to give rise to ferrimagnetic (FIM)
+behavior in the magnetic susceptibility. Upon decreasing the temperature ($T <
+T_\textup{C}^\textup{Co}$), the magnetocrystalline anisotropy breaks up the FM
+order of Co by aligning the moments with the local easy axes of the various
+grains, leading to a spin reorientation transition at
+$T_\textup{R}^\textup{Co}$. By applying a magnetic field,
+$T_\textup{R}^\textup{Co}$ monotonically decreases to lower temperatures, while
+the $T_\textup{N}^\textup{Gd}$ is relatively robust against the external field.
+On the other hand, the applied magnetic field pulls the magnetization of grains
+from the local easy direction to the field direction via a first-order
+reorientation transition, with the transition field ($H_\textup{M}$) increasing
+upon cooling the temperature.",1502.05139v1
+2010-12-21,Magnetocrystalline anisotropy and uniaxiality of MnAs/GaAs(100) films,"We present an investigation of the magnetic behavior of epitaxial MnAs films
+grown on GaAs(100). We address the dependence of the magnetic moment,
+ferromagnetic transition temperature ($T_c$) and magnetocrystalline anisotropy
+constants on epitaxial conditions. From thorough structural and magnetic
+investigations, our findings indicate a more complex relationship between
+strain and magnetic properties in MnAs films than a simple stretch/compression
+of the unit cell axes. While a small increase is seen in the anisotropy
+constants the enhancement of the magnetic moment at saturation is significant.
+X-ray magnetic circular dichroism results show a behavior of the spin- and
+orbital-moment which is consistent with a structural transition at $T_c$. In
+particular, we find that the ratio of the orbital to spin moment shows a marked
+increase in the coexistence region of the ferromagnetic $\alpha$- and
+paramagnetic $\beta$-phases, a result that is well in accord with the observed
+increase of the $c/a$-ratio in the same temperature region. The \textit{ab
+initio} density functional calculations reveal that the magnetic properties are
+more sensitive towards change in in-plane axis as compared to a change of the
+out-of-plane axis, which is explained by the analysis of band structures. The
+effects of electron correlation in MnAs using \textit{ab initio} dynamical mean
+field theory are also presented.",1012.4717v1
+2018-03-22,Tuning magnetocrystalline anisotropy of Fe$_{3}$Sn by alloying,"The electronic structure, magnetic properties and phase formation of
+hexagonal ferromagnetic Fe$_{3}$Sn-based alloys have been studied from first
+principles and by experiment. The pristine Fe$_{3}$Sn compound is known to
+fulfill all the requirements for a good permanent magnet, except for the
+magnetocrystalline anisotropy energy (MAE). The latter is large, but planar,
+i.e. the easy magnetization axis is not along the hexagonal c direction,
+whereas a good permanent magnet requires the MAE to be uniaxial. Here we
+consider Fe$_{3}$Sn$_{0.75}$M$_{0.25}$, where M= Si, P, Ga, Ge, As, Se, In, Sb,
+Te and Bi, and show how different dopants on the Sn sublattice affect the MAE
+and can alter it from planar to uniaxial. The stability of the doped Fe$_{3}$Sn
+phases is elucidated theoretically via the calculations of their formation
+enthalpies. A micromagnetic model is developed in order to estimate the energy
+density product (BH)max and coercive field $\mu_{0}$H$_{c}$ of a potential
+magnet made of Fe$_{3}$Sn$_{0.75}$Sb$_{0.25}$, the most promising candidate
+from theoretical studies. The phase stability and magnetic properties of the
+Fe$_{3}$Sn compound doped with Sb and Mn has been checked experimentally on the
+samples synthesised using the reactive crucible melting technique as well as by
+solid state reaction. The Fe$_{3}$Sn-Sb compound is found to be stable when
+alloyed with Mn. It is shown that even small structural changes, such as a
+change of the c/a ratio or volume, that can be induced by, e.g., alloying with
+Mn, can influence anisotropy and reverse it from planar to uniaxial and back.",1803.08292v1
+2018-07-27,Magnetocrystalline anisotropy of Fe5PB2 and its alloys with Co and 5d elements: a combined first-principles and experimental study,"The Fe$_5$PB$_2$ compound offers tunable magnetic properties via the
+possibility of various combinations of substitutions on the Fe and P-sites.
+Here, we present a combined computational and experimental study of the
+magnetic properties of (Fe$_{1-x}$Co$_{x}$)$_5$PB$_2$. Computationally, we are
+able to explore the full concentration range, while the real samples were only
+obtained for 0 <= x <= 0.7. The calculated magnetic moments, Curie
+temperatures, and magnetocrystalline anisotropy energies (MAEs) are found to
+decrease with increasing Co concentration. Co substitution allows for tuning
+the Curie temperature in a wide range of values, from about six hundred to zero
+kelvins. As the MAE depends on the electronic structure in the vicinity of
+Fermi energy, the geometry of the Fermi surface of Fe$_5$PB$_2$ and the
+k-resolved contributions to the MAE are discussed. Low temperature measurements
+of an effective anisotropy constant for a series of
+(Fe$_{1-x}$Co$_{x}$)$_5$PB$_2$ samples determined the highest value of 0.94 MJ
+m$^{-3}$ for the terminal Fe$_5$PB$_2$ composition, which then decreases with
+increasing Co concentration, thus confirming the computational result that Co
+alloying of Fe$_5$PB$_2$ is not a good strategy to increase the MAE of the
+system. However, the relativistic version of the fixed spin moment method
+reveals that a reduction in the magnetic moment of Fe$_5$PB$_2$, by about 25%,
+produces a fourfold increase of the MAE. Furthermore, calculations for
+(Fe$_{0.95}$X$_{0.05}$)$_5$PB$_2$ (X = 5$d$ element) indicate that 5% doping of
+Fe$_5$PB$_2$ with W or Re should double the MAE. These are results of high
+interest for, e.g., permanent magnet applications, where a large MAE is
+crucial.",1807.10649v3
+2021-08-06,"Strong magneto-optical and anomalous transport manifestations in two-dimensional van der Waals magnets Fe$_n$GeTe$_2$ ($n$ = 3, 4, 5)","Utilizing the first-principles calculations together with the group theory
+analysis, we systematically investigate the magnetocrystalline anisotropy
+energy, magneto-optical effect, and anomalous transport properties (including
+anomalous Hall, Nernst, and thermal Hall effects) of monolayer and bilayer
+Fe$_n$GeTe$_2$ ($n$ = 3, 4, 5). The monolayer Fe$_n$GeTe$_2$ ($n$ = 3, 4, 5)
+exhibits the out-of-plane, in-plane, and in-plane ferromagnetic orders with
+considerable magnetocrystalline anisotropy energies of -3.17, 4.42, and 0.58
+meV/f.u., respectively. Ferromagnetic order is predicted in bilayer
+Fe$_4$GeTe$_2$ while antiferromagnetic order prefers in bilayer Fe$_3$GeTe$_2$
+and Fe$_5$GeTe$_2$. The group theory analysis reveals that in addition to
+monolayer ferromagnetic Fe$_n$GeTe$_2$ ($n$ = 3, 4, 5), the magneto-optical and
+anomalous transport phenomena surprisingly exist in bilayer antiferromagnetic
+Fe$_5$GeTe$_2$, which is much rare in realistic collinear antiferromagnets. If
+spin magnetic moments of monolayer and bilayer Fe$_n$GeTe$_2$ are reoriented
+from the in-plane to out-of-plane direction, the magneto-optical and anomalous
+transport properties enhance significantly, presenting strong magnetic
+anisotropy. We also demonstrate that the anomalous Hall effect decreases with
+the temperature increases. The gigantic anomalous Nernst and thermal Hall
+effects are found in monolayer and bilayer ferromagnetic Fe$_n$GeTe$_2$, and
+the largest anomalous Nernst and thermal Hall conductivities, respectively, of
+-3.31 A/Km and 0.22 W/Km at 130 K are observed in bilayer ferromagnetic
+Fe$_4$GeTe$_2$. Especially, bilayer antiferromagnetic Fe$_5$GeTe$_2$ exhibits
+large zero-temperature anomalous Hall conductivity of 2.63 e$^2$/h as well as
+anomalous Nernst and thermal Hall conductivities of 2.76 A/Km and 0.10 W/Km at
+130 K, respectively.",2108.02926v2
+2000-05-24,Crystal-field interactions in PrRu2Si2,"Ferromagnetic compound PrRu2Si2 exhibits a giant magnetocrystalline
+anisotropy of about 400 T. Its ordered moment below Tc=14K reaches 2.7 mB and
+is parallel to [0 0 1] crystalline direction. We have attributed the magnetism
+of PrRu2S2 to the Pr ions and performed calculations of the fine electronic
+structure of the Pr ion in the tetragonal symmetry, relevant to PrRu2Si2 taking
+into account crystal-field and inter-site, spin-dependent exchange
+interactions. Spin-dependent interactions have been taken into account by means
+of molecular-field approximation. The derived energy level scheme is associated
+with the removal of the degeneracy of the lowest multiplet given by Hund's
+rules, 3H4. Magnetic and electronic properties resulting from this fine
+structure are compared with all known experimental results. Our calculations
+reproduce well the zero-temperature moment, temperature dependence of the
+magnetic susceptibility, single-crystalline magnetization curves with the
+anisotropy field of 400T, the specific heat with the sharp peak at Tc as well
+as inelastic-neutron-scattering data.",0005406v1
+2000-06-26,Wess-Zumino-Berry phase interference in spin tunneling at excited levels with a magnetic field,"Macroscopic quantum coherence and spin-phase interference are studied between
+excited levels in single-domain ferromagnetic particles in a magnetic field
+along the hard anisotropy axis. The system has the general structure of
+magnetocrystalline anisotropy, such as biaxial, trigonal, tetragonal, and
+hexagonal symmetry. This study not only just yields the previous spin-phase
+interference results for the ground state tunneling, but also provide a
+generalization of the Kramers degeneracy to coherently spin tunneling at
+low-lying excited states. These analytical results are found to be in good
+agreement with the numerical diagonalization. We also discuss the transition
+from quantum to classical behavior and the possible relevance to experiment.",0006392v2
+2002-06-19,Magnetic structure of antiferromagnetic NdRhIn5,"The magnetic structure of antiferromagnetic NdRhIn5 has been determined using
+neutron diffraction. It has a commensurate antiferromagnetic structure with a
+magnetic wave vector (1/2,0,1/2) below T_N = 11K. The staggered Nd moment at
+1.6K is 2.6mu_B aligned along the c-axis. We find the magnetic structure to be
+closely related to that of its cubic parent compound NdIn3 below 4.6K. The
+enhanced T_N and the absence of additional transitions below T_N for NdRhIn5
+are interpreted in terms of an improved matching of the
+crystalline-electric-field (CEF), magnetocrystalline, and exchange interaction
+anisotropies. In comparison, the role of these competing anisotropies on the
+magnetic properties of the structurally related compound CeRhIn5 is discussed.",0206381v1
+2004-07-02,Large LFMR observed in twinned La2/3Ca1/3MnO3 thin films epitaxially grown on YSZ-buffered SOI substrates,"La2/3Ca1/3MnO3 thin films have been grown on yttria-stabilized zirconia (YSZ)
+buffered silicon-on-insulator (SOI) substrate by the pulsed laser deposition
+technique. While full cube-on-cube epitaxy was achieved for the YSZ layer, the
+top manganite layer was multi-domain-oriented, with a coexistence of
+cube-on-cube and cube-on-diagonal epitaxy. Due to a combined influence from the
+magnetocrystalline anisotropy and the magnetoelastic anisotropy, in zero field
+the local spin orientation varies across the twin boundaries. As a result, a
+quite large low-field magnetoresistance (LFMR) based on spin-dependent
+tunnelling was observed. The film shows a resistance change of ~20% in a
+magnetic field <1000 Oe at 50 K, which is promising for real applications.",0407053v1
+2006-03-22,"Out-of-plane magnetization reversal processes of (Ga,Mn)As with two different hole concentrations","We study magnetization reversal processes of in-plane magnetized (Ga,Mn)As
+epilayers with different hole concentrations in out-of-plane magnetic fields
+using magnetotransport measurements. A clear difference in the magnetization
+process is found in two separate samples with hole concentrations of 10^20
+cm^-3 and 10^21 cm^-3 as the magnetization rotates from the out-of-plane
+saturation to the in-plane remanence. Magnetization switching process from the
+in-plane remanence to the out-of-plane direction, on the other hand, shows no
+hole concentration dependence, where the switching process occurs via domain
+wall propagation. We show that the balance of <100> cubic magnetocrystalline
+anisotropy and uniaxial [110] anisotropy gives an understanding of the
+difference in the out-of-plane magnetization processes of (Ga,Mn)As epilayers.",0603568v1
+2006-03-28,Ferromagnetic one dimensional Ti atomic chain,"Using the full potential linearized augmented plane wave (FLAPW) method, we
+have explored the magnetic properties of one dimensional (1D) Ti atomic chain.
+Astonishingly, we for the first time observed that the 1D Ti atomic chain has
+ferromagnetic ground state even on NiAl(110) surface although the Ti has no
+magnetic moment in bulk or macroscopic state. It was found that the physical
+property of direct exchange interaction among Ti atoms occurred in free
+standing state is well preserved on NiAl(110) surface and this feature has an
+essential role in ferromagnetism of 1D Ti atomic chain. It was shown that the
+m=$|2|$ state has the largest contribution to the magnetic moment of Ti atom
+grown on NiAl(110) surface. In addition, we found that the magnetic dipole
+interaction is a key factor in the study of magnetic anisotropy, not the
+magnetocrystalline anisotropy arising from spin-orbit interaction.",0603740v1
+2007-05-03,"Domain imaging and domain wall propagation in (Ga,Mn)As thin films with tensile strain","We have performed spatially resolved Polar Magneto-Optical Kerr Effect
+Microscopy measurements on as-grown and annealed Ga0.95Mn0.05As thin films with
+tensile strain. We find that the films exhibit very strong perpendicular
+magnetic anisotropy which is increased upon annealing. During magnetic
+reversal, the domain walls propagate along the direction of surface ripples for
+the as-grown sample at low temperatures and along the [110] direction for the
+annealed sample. This indicates that the magnetic domain pattern during
+reversal is determined by a combination of magnetocrystalline anisotropy and a
+distribution of pinning sites along the surface ripples that can be altered by
+annealing. These mechanisms could lead to an effective method of controlling
+domain wall propagation.",0705.0474v1
+2008-01-06,Voltage control of magnetocrystalline anisotropy in ferromagnetic - semiconductor/piezoelectric hybrid structures,"We demonstrate dynamic voltage control of the magnetic anisotropy of a
+(Ga,Mn)As device bonded to a piezoelectric transducer. The application of a
+uniaxial strain leads to a large reorientation of the magnetic easy axis which
+is detected by measuring longitudinal and transverse anisotropic
+magnetoresistance coefficients. Calculations based on the mean-field
+kinetic-exchange model of (Ga,Mn)As provide microscopic understanding of the
+measured effect. Electrically induced magnetization switching and detection of
+unconventional crystalline components of the anisotropic magnetoresistance are
+presented, illustrating the generic utility of the piezo voltage control to
+provide new device functionalities and in the research of micromagnetic and
+magnetotransport phenomena in diluted magnetic semiconductors.",0801.0886v2
+2009-08-27,Magnetocrystalline anisotropy and antiferromagnetic phase transition in PrRh$_{2}$Si$_{2}$,"We present magnetic and transport properties of PrRh$_{2}$Si$_{2}$ single
+crystals which exhibit antiferromagnetic order below T$_{N}$ = 68 K. Well
+defined anomalies due to magnetic phase transition are observed in magnetic
+susceptibility, resistivity, and specific heat data. The T$_{N}$ of 68 K for
+PrRh$_{2}$Si$_{2}$ is much higher than 5.4 K expected on the basis of de-Gennes
+scaling. The magnetic susceptibility data reveal strong uniaxial anisotropy in
+this compound similar to that of PrCo$_{2}$Si$_{2}$. With increasing pressure
+T$_{N}$ increases monotonically up to T$_N$ = 71.5 K at 22.5 kbar.",0908.4017v1
+2010-01-26,Competing magnetic anisotropies in atomic-scale junctions,"Using first-principles calculations, we study the magnetism of 5d
+transition-metal atomic junctions including structural relaxations and
+spin-orbit coupling. Upon stretching monatomic chains of W, Ir, and Pt
+suspended between two leads, we find the development of strong magnetism and
+large values of the magnetocrystalline anisotropy energy (MAE) of up to 30 meV
+per chain atom. We predict that switches of the easy magnetization axis of the
+nanocontacts upon elongation should be observable by ballistic anisotropic
+magnetoresistance measurements. Due to the different local symmetry, the
+contributions to the MAE of the central chain atoms and chain atoms in the
+vicinity of the leads can have opposite signs which reduces the total MAE. We
+demonstrate that this effect occurs independent of the chain length or geometry
+of the electrodes.",1001.4618v1
+2010-08-12,Rotational Doppler Effect in Magnetic Resonance,"We compute the shift in the frequency of the spin resonance in a solid that
+rotates in the field of a circularly polarized electromagnetic wave. Electron
+spin resonance, nuclear magnetic resonance, and ferromagnetic resonance are
+considered. We show that contrary to the case of the rotating LC circuit, the
+shift in the frequency of the spin resonance has strong dependence on the
+symmetry of the receiver. The shift due to rotation occurs only when rotational
+symmetry is broken by the anisotropy of the gyromagnetic tensor, by the shape
+of the body, or by magnetocrystalline anisotropy. General expressions for the
+resonance frequency and power absorption are derived and implications for
+experiment are discussed.",1008.2142v1
+2010-10-25,High-temperature magnetic properties of noninteracting single-domain Fe3O4 nanoparticles,"Magnetic measurements have been performed on 40-nm sphere-like Fe3O4
+nanoparticles using a Quantum Design vibrating sample magnetometer. Coating
+Fe3O4 nanoparticles with SiO2 effectively eliminates magnetic interparticle
+interactions so that the coercive field HC in the hightemperature range between
+300 K and the Curie temperature (855 K) can be well fitted by an expression for
+noninteracting randomly oriented single-domain particles. From the fitting
+parameters, the effective anisotropy constant K is found to be (1.68 \pm 0.17)
+\times 105 erg/cm3, which is slightly larger than the bulk magnetocrystalline
+anisotropy constant of 1.35 \times 105 erg/cm3. Moreover, the inferred mean
+particle diameter from the fitting parameters is in quantitative agreement with
+that determined from transmission electron microscope. Such a quantitative
+agreement between data and theory suggests that the assemble of our SiO2-coated
+sphere-like Fe3O4 nanopartles represents a good system of noninteracting
+randomly-oriented single-domain particles.",1010.5264v2
+2010-12-21,"Detection of stacking faults breaking the [110]/[1-10] symmetry in ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P)","We report high resolution x-ray diffraction measurements of (Ga,Mn)As and
+(Ga,Mn)(As,P) epilayers. We observe a structural anisotropy in the form of
+stacking faults which are present in the (111) and (11-1) planes and absent in
+the (-111) and (1-11) planes. The stacking faults produce no macroscopic
+strain. They occupy 0.01 - 0.1 per cent of the epilayer volume. Full-potential
+density functional calculations evidence an attraction of Mn_Ga impurities to
+the stacking faults. We argue that the enhanced Mn density along the common
+[1-10] direction of the stacking fault planes produces sufficiently strong
+[110]/[1-10] symmetry breaking mechanism to account for the in-plane uniaxial
+magnetocrystalline anisotropy of these ferromagnetic semiconductors.",1012.4690v1
+2011-03-19,Magnetic properties and energy absorption of CoFe2O4 nanoparticles for magnetic hyperthermia,"We have studied the magnetic and power absorption properties of three samples
+of CoFe2O4 nanoparticles with sizes from 5 to 12 nm prepared by thermal
+decomposition of Fe (acac)3 and Co(acac)2 at high temperatures. The blocking
+temperatures TB estimated from magnetization M(T) curves spanned the range 180
+< TB < 320 K, reflecting the large magnetocrystalline anisotropy of these
+nanoparticles. Accordingly, high coercive fields HC \approx 1.4 - 1.7 T were
+observed at low temperatures. Specific Power Absorption (SPA) experiments
+carried out in ac magnetic fields indicated that, besides particle volume, the
+effective magnetic anisotropy is a key parameter determining the absorption
+efficiency. SPA values as high as 98 W/g were obtained for nanoparticles with
+average size of \approx12 nm.",1103.3786v1
+2011-11-23,Magnetic and structural characterization of nanosized BaCo_xZn_{2-x}Fe_{16}O_{27} hexaferrite in the vicinity of spin reorientation transition,"Numerous applications of hexagonal ferrites are related to their easy axis or
+easy plane magnetocrystalline anisotropy configurations. Certain W-type
+ferrites undergo spin reorientation transitions (SRT) between different
+anisotropy states on magnetic field or temperature variation. The transition
+point can be tuned by modifying the chemical composition, which suggests a
+potential application of hexaferrites in room temperature magnetic
+refrigeration. Here we present the results of structural and magnetic
+characterization of BaCo_xZn_{2-x}Fe_{16}O_{27} (0.7 \leq x \leq 2) doped
+barium ferrites. Fine powders were prepared using a sol-gel citrate precursor
+method. Crystal structures and particle size distributions were examined by
+X-ray diffraction and transmission electron microscopy. The optimal synthesis
+temperature ensuring complete formation of single W-phase with limited grain
+growth has been determined. Spin reorientation transitions were revealed by
+thermomagnetic analysis and AC susceptibility measurements.",1111.5453v1
+2012-01-17,Spin-orbit field switching of magnetization in ferromagnetic films with perpendicular anisotropy,"As an alternative to conventional magnetic field, the effective spin-orbit
+field in transition metals, derived from the Rashba field experienced by
+itinerant electrons confined in a spatial inversion asymmetric plane through
+the s-d exchange interaction, is proposed for the manipulation of
+magnetization. Magnetization switching in ferromagnetic thin films with
+perpendicular magnetocrystalline anisotropy can be achieved by current induced
+spin-orbit field, with small in-plane applied magnetic field. Spin-orbit field
+induced by current pulses as short as 10 ps can initiate ultrafast
+magnetization switching effectively, with experimentally achievable current
+densities. The whole switching process completes in about 100 ps.",1201.3505v4
+2012-09-12,Spin configurations in Co2FeAl0.4Si0.6 Heusler alloy thin film elements,"We determine experimentally the spin structure of half-metallic
+Co2FeAl0.4Si0.6 Heusler alloy elements using magnetic microscopy. Following
+magnetic saturation, the dominant magnetic states consist of quasi-uniform
+configurations, where a strong influence from the magnetocrystalline anisotropy
+is visible. Heating experiments show the stability of the spin configuration of
+domain walls in confined geometries up to 800 K. The switching temperature for
+the transition from transverse to vortex walls in ring elements is found to
+increase with ring width, an effect attributed to structural changes and
+consequent changes in magnetic anisotropy, which start to occur in the narrower
+elements at lower temperatures.",1209.2702v1
+2013-08-07,Magnetocrystalline anisotropy energy for adatoms and monolayers on non-magnetic substrates: where does it comes from?,"The substrate contribution to the magnetic anisotropy energy (MAE) of
+supported nanostructures can be quantified by a site-selective manipulation of
+the spin-orbit coupling (SOC) and the effective exchange field B_ex. A
+systematic study of Co adatoms and Co monolayers on the (111) surfaces of Cu,
+Ag, Au, Pd and Pt is performed to study common trends in this class of
+materials. It is found that for adatoms, the substrate contribution is
+relatively small (10-30% of the MAE) while for monolayers, the substrate
+contribution can be substantial. The contribution from the SOC is much more
+important than the contribution from the exchange field B_ex, except for highly
+polarizable substrates with a strong SOC (such as Pt). The substrate always
+promotes the tendency to an out-of-plane orientation of the easy magnetic axis
+for all the investigated systems.",1308.1597v3
+2014-10-23,Surface aligned magnetic moments and hysteresis of an endohedral single-molecule magnet on a metal,"The interaction between the endohedral unit in the single-molecule magnet
+Dy$_2$ScN@C$_{80}$ and a rhodium (111) substrate leads to alignment of the Dy
+4$f$ orbitals. The resulting orientation of the Dy$_2$ScN plane parallel to the
+surface is inferred from comparison of the angular anisotropy of x-ray
+absorption spectra and multiplet calculations in the corresponding ligand
+field. The x-ray magnetic circular dichroism (XMCD) is also angle dependent and
+signals strong magnetocrystalline anisotropy. This directly relates geometric
+and magnetic structure. Element specific magnetization curves from different
+coverages exhibit hysteresis at a sample temperature of $\sim4$ K. From the
+measured hysteresis curves we estimate the zero field remanence life-time
+during x-ray exposure of a sub-monolayer to be about 30 seconds.",1410.6272v2
+2015-02-28,Band-filling effect on magnetic anisotropy using a Green's function method,"We use an analytical model to describe the magnetocrystalline anisotropy
+energy (MAE) in solids as a function of band filling. The MAE is evaluated in
+second-order perturbation theory, which makes it possible to decompose the MAE
+into a sum of transitions between occupied and unoccupied pairs. The model
+enables us to characterize the MAE as a sum of contributions from different,
+often competing terms. The nitridometalates Li$_{2}$[(Li$_{1-x}$T$_{x}$)N],
+with $T$=Mn, Fe, Co, Ni, provide a system where the model is very effective
+because atomic like orbital characters are preserved and the decomposition is
+fairly clean. Model results are also compared against MAE evaluated directly
+from first-principles calculations for this system. Good qualitative agreement
+is found.",1503.00063v2
+2015-06-01,Evaluation of (BH)max and magnetic anisotropy of cobalt ferrite nanoparticles synthesized in gelatin,"CoFe2O4 nanoparticles were synthesized using gelatin as a polymerizing agent.
+Structural, morphological and magnetic properties of samples treated at
+different temperatures were investigated by X-ray diffraction, scanning
+electron microscopy, Mossbauer spectroscopy and magnetization measurements. Our
+results revealed that the samples annealed at 623 K and temperatures above 973
+K have a cation distributions given by (Co0.19Fe0.81)[Co0.81Fe1.19]O4 and
+(Co0.06Fe0.94)[Co0.94Fe1.06]O4, respectively. The particle sizes varied from 73
+to 296 nm and the magnetocrystalline anisotropy, K1, has values ranging from
+2.60x10^6 to 2.71x10^6 J/m3, as determined from the law of approach to
+saturation applied to the MxH data at high field. At 5 K, the saturation
+magnetization, coercive field and (BH)max varied from 76 to 95 Am2/kg, 479.9 to
+278.5 kA/m and 9.7 to 20.9 kJ/m3, respectively. The reported values are in good
+agreement with near-stoichiometric cobalt ferrite samples.",1506.00505v1
+2015-07-24,Theory of perpendicular magnetocrystalline anisotropy in Fe/MgO (001),"The origin of large perpendicular magneto-crystalline anisotropy (PMCA) in
+Fe/MgO (001) is revealed by comparing Fe layers with and without the MgO.
+Although Fe-O $p$-$d$ hybridization is weakly present, it cannot be the main
+origin of the large PMCA as claimed in previous study. Instead, perfect epitaxy
+of Fe on the MgO is more important to achieve such large PMCA. As an evidence,
+we show that the surface layer in a clean free-standing Fe (001) dominantly
+contributes to $E_{MCA}$, while in the Fe/MgO, those by the surface and the
+interface Fe layers contribute almost equally. The presence of MgO does not
+change positive contribution from $\langle xz|\ell_Z|yz\rangle$, whereas it
+reduces negative contribution from $\langle z^2|\ell_X|yz\rangle$ and $\langle
+xy|\ell_X|xz,yz\rangle$.",1507.06799v1
+2015-09-30,Magnetic anisotropy in Shiba bound states across a quantum phase transition,"The exchange coupling between magnetic adsorbates and a superconducting
+substrate leads to Shiba states inside the superconducting energy gap and a
+Kondo resonance outside the gap. The exchange coupling strength determines
+whether the quantum many-body ground state is a Kondo singlet or a singlet of
+the paired superconducting quasiparticles. Here, we use scanning tunneling
+spectroscopy to identify the different quantum ground states of Manganese
+phthalocyanine on Pb(111). We observe Shiba states, which are split into
+triplets by magnetocrystalline anisotropy. Their characteristic spectral weight
+yields an unambiguous proof of the nature of the quantum ground state.",1509.09108v1
+2016-02-09,Magnetocrystalline anisotropy of Fe and Co slabs and clusters on SrTiO$\_3$ by first-principles,"In this work, we present a detailed theoretical investigation of the
+electronic and magnetic properties of ferromagnetic slabs and clusters
+deposited on SrTiO$\_3$ via first-principles, with a particular emphasis on the
+magneto-crystalline anisotropy (MCA). We found that in the case of Fe films
+deposited on SrTiO$\_3$ the effect of the interface is to quench the MCA
+whereas for Cobalt we observe a change of sign of the MCA from in-plane to
+out-of-plane as compared to the free surface. We also find a strong enhancement
+of MCA for small clusters upon deposition on a SrTiO$\_3$ substrate. The
+hybridization between the substrate and the $d$-orbitals of the cluster
+extending in-plane for Fe and out-of-plane for Co is at the origin of this
+enhancement of MCA. As a consequence, we predict that the Fe nanocrystals (even
+rather small) should be magnetically stable and are thus good potential
+candidates for magnetic storage devices.",1602.03141v1
+2016-04-01,Magnetocrystalline anisotropy of FePt: a detailed view,"To get a reliable ab-initio value for the magneto-crystalline anisotropy
+(MCA) energy of FePt, we employ the full-potential linearized augmented plane
+wave (FLAPW) method and the full-potential Korringa-Kohn-Rostoker (KKR) Green
+function method. The MCA energies calculated by both methods are in a good
+agreement with each other. As the calculated MCA energy significantly differs
+from experiment, it is clear that many-body effects beyond the local density
+approximation are essential. It is not really important whether relativistic
+effects for FePt are accounted for by solving the full Dirac equation or
+whether the spin-orbit coupling (SOC) is treated as a correction to the
+scalar-relativistic Hamiltonian. From the analysis of the dependence of the MCA
+energy on the magnetization angle and on the SOC strength it follows that the
+main mechanism of MCA in FePt can be described within second order perturbation
+theory. However, a distinct contribution not accountable for by second order
+perturbation theory is present as well.",1604.00176v3
+2016-07-07,Giant perpendicular magnetic anisotropy energies in CoPt thin films: Impact of reduced dimensionality and imperfections,"The impact of reduced dimensionality on the magnetic properties of the
+tetragonal L1$_{0}$ CoPt alloy is investigated from ab-initio considering
+several kinds of surface defects. By exploring the dependence of the
+magnetocrystalline anisotropy energy (MAE) on the thickness of CoPt thin films,
+we demonstrate the crucial role of the chemical nature of the surface. For
+instance, Pt-terminated thin films exhibit huge MAEs which can be 1000% larger
+than those of Co-terminated films. Besides the perfect thin films, we
+scrutinize the effect of defective surfaces such as stacking faults or
+anti-sites on the surface layers. Both types of defects reduce considerably the
+MAE with respect to the one obtained for Pt-terminated thin films. A detailed
+analysis of the electronic structure of the thin films is provided with a
+careful comparison to the CoPt bulk case. The behavior of the MAEs is then
+related to the location of the different virtual bound states utilising second
+order perturbation theory.",1607.01919v2
+2016-11-26,Specific Heat of Spin Excitations Measured by FerromagneticResonance,"Using ferromagnetic-resonance spectroscopy (FMR), we investigate the
+anisotropic properties of epitaxial 3 nmPt/2 nmAg/10 nmFe/10 nmAg/GaAs(001)
+films in fully saturated meta-stable states at temperatures ranging from 70 K
+to 280 K. By comparison to spin-wave theory calculations, we identify the role
+of thermal fluctuation of magnons in overcoming the energy barrier associated
+with these meta-stable states. We show that the energy associated with the size
+of the barrier that bounds the meta-stable regime is proportional to the heat
+stored in the magnonic bath. Our findings offer the possibility to measure the
+magnonic contribution to the heat capacity by FMR, independent of other
+contributions at temperatures ranging from 0 K to ambient temperature and
+above. The only requirement being that the selected sample exhibits magnetic
+anisotropy, here, magnetocrystalline anisotropy.",1611.08713v2
+2017-02-22,Missing magnetism in Sr$_{4}$Ru$_{3}$O$_{10}$: Indication for Antisymmetric Exchange Interaction,"We report a detailed study of the magnetization modulus as a function of
+temperature and applied magnetic field under varying angle in
+Sr$_{4}$Ru$_{3}$O$_{10}$ close to the metamagnetic transition at
+$H_{c}\backsimeq 2.5\,$T for $H \perp c$. We confirm that the double-feature at
+$H_{c}$ is robust without further splitting for temperatures below 1.8 K down
+to 0.48 K. The metamagnetism in Sr$_{4}$Ru$_{3}$O$_{10}$ is accompanied by a
+reduction of the magnetic moment in the plane of rotation and large
+field-hysteretic behavior. The double anomaly shifts to higher fields by
+rotating the field from $H\,\perp \,c$ to $H\,\parallel\,c$. We compare our
+experimental findings with numerical simulations based on spin reorientation
+models caused by intrinsic magnetocrystalline anisotropy and Zeeman effect.
+Crystal anisotropy is able to explain a metamagnetic transition in the
+ferromagnetic ordered system Sr$_{4}$Ru$_{3}$O$_{10}$, but a
+Dzyaloshinskii-Moriya term is crucial to account for a reduction of the
+magnetic moment as discovered in the experiments.",1702.06882v1
+2017-08-28,Electric-field-induced changes of magnetic moments and magnetocrystalline anisotropy in ultrathin cobalt films,"In this study, the microscopic origins of the voltage-controlled magnetic
+anisotropy (VCMA) in 3d-ferromagnetic metals are revealed. Using in-situ X-ray
+fluorescence spectroscopy that provides a high quantum efficiency,
+electric-field-induced changes in orbital magnetic moment and magnetic dipole
+Tz terms in ultrathin Co films are demonstrated. An orbital magnetic moment
+difference of 0.013{\mu}B. was generated in the presence of electric fields of
++(-)0.2 V/nm. The VCMA of Co was properly estimated by the induced change in
+orbital magnetic moment, according to the perturbation theory model. The
+induced change in magnetic dipole Tz term only slightly contributed to the VCMA
+in 3d-ferromagnetic metals.",1708.08549v2
+2018-02-15,Origin of spin reorientation transitions in antiferromagnetic MnPt-based alloys,"Antiferromagnetic MnPt exhibits a spin reorientation transition (SRT) as a
+function of temperature, and off-stoichiometric Mn-Pt alloys also display SRTs
+as a function of concentration. The magnetocrystalline anisotropy in these
+alloys is studied using first-principles calculations based on the coherent
+potential approximation and the disordered local moment method. The anisotropy
+is fairly small and sensitive to the variations in composition and temperature
+due to the cancellation of large contributions from different parts of the
+Brillouin zone. Concentration and temperature-driven SRTs are found in
+reasonable agreement with experimental data. Contributions from specific
+band-structure features are identified and used to explain the origin of the
+SRTs.",1802.05685v2
+2018-05-16,Magnetic properties of single crystalline itinerant ferromagnet AlFe2B2,"Single crystals of AlFe$_{2}$B$_{2}$ have been grown using the self flux
+growth method and then measured the structural properties, temperature and
+field dependent magnetization, and temperature dependent electrical resistivity
+at ambient as well as high pressure. The Curie temperature of AlFe$_{2}$B$_{2}$
+is determined to be $274$~K. The measured saturation magnetization and the
+effective moment for paramagnetic Fe-ion indicate the itinerant nature of the
+magnetism with a Rhode-Wohlfarth ratio $ \frac{M_{C}}{M_{sat}}\approx 1.14$.
+Temperature dependent resistivity measurements under hydrostatic pressure shows
+that transition temperature \textit{T$_C$} is suppressed down to 255 K for $p =
+2.24$~GPa pressure with a suppression rate of $\sim -8.9$~K/GPa. The anisotropy
+fields and magnetocrystalline anisotropy constants are in reasonable agreement
+with density functional theory calculations.",1805.06373v1
+2019-02-10,Spin dynamics of anisotropic azimuthal modes in heterogeneous magnetic nanodisks,"It is well known that azimuthal spin wave modes of magnetic vortex state in
+permalloy nanodisks have circular symmetry. Intuitively, magnetic materials
+having magnetocrystalline anisotropy is not compatible with the circular
+symmetry of the azimuthal modes. In this article, however, we report cubic
+azimuthal modes in heterogeneous nanodisks consisting of a permalloy core and a
+Fe shell. The fourfold symmetry of azimuthal modes is due to the exchange, and
+magneto-static, interactions between the permalloy core and the Fe shell. In
+comparison to results of circular azimuthal mode, the vortex switching occurs
+considerably faster under the excitation of cubic azimuthal mode. The gyration
+path of vortex core turns into square under the influence of induced cubic
+anisotropy in the Py region. We find out periodic oscillation of the vortex
+core size and the gyration speed as well. Our findings may offer a new route
+for spintronic applications using heterogeneous magnetic nanostructures.",1902.03536v1
+2019-06-28,Zero-field propagation of spin waves in waveguides prepared by focused ion beam direct writing,"Metastable face-centered-cubic Fe78Ni22 thin films grown on Cu(001)
+substrates are excellent candidates for focused ion beam direct writing of
+magnonic structures due to their favorable magnetic properties after
+ion-beam-induced transformation. The focused ion beam transforms the originally
+nonmagnetic fcc phase into the ferromagnetic bcc phase with additional control
+over the direction of uniaxial magnetic in-plane anisotropy. The
+magnetocrystalline anisotropy in transformed areas is strong enough to
+stabilize the magnetization in transverse direction to the long axis of narrow
+waveguides. Therefore, it is possible to propagate spin waves in these
+waveguides without the presence of an external magnetic field in the favorable
+Demon-Eshbach geometry. Phase-resolved micro-focused Brillouin light scattering
+yields the dispersion relation of these waveguides in zero as well as in
+nonzero external magnetic fields.",1906.12254v2
+2019-10-23,Computational screening of Fe-Ta hard magnetic phases,"In this work we perform a systematic calculation of the Fe-Ta phase diagram
+to discover novel hard magnetic phases. By using structure prediction methods
+based on evolutionary algorithms, we identify two new energetically stable
+magnetic structures: a tetragonal Fe$_3$Ta (space group 122) and cubic Fe$_5$Ta
+(space group 216) binary phases. The tetragonal structure is estimated to have
+both high saturation magnetization ($\mu_0$M$_s$=1.14 T) and magnetocrystalline
+anisotropy (K$_1$=2.17 MJ/m$^3$) suitable for permanent magnet applications.
+The high-throughput screening of magneto-crystalline anisotropy also reveals
+two low energy metastable hard magnetic phases: Fe$_5$Ta$_2$ (space group 156)
+and Fe$_{6}$Ta (space group 194), that may exhibit intrinsic magnetic
+properties comparable to SmCo$_5$ and Nd$_2$Fe$_{14}$B, respectively.",1910.10531v1
+2019-11-02,Tuning Non-Gilbert-type damping in FeGa films on MgO(001) via oblique deposition,"The ability to tailor the damping factor is essential for spintronic and
+spin-torque applications. Here, we report an approach to manipulate the damping
+factor of FeGa/MgO(001) films by oblique deposition. Owing to the defects at
+the surface or interface in thin films, two-magnon scattering (TMS) acts as a
+non-Gilbert damping mechanism in magnetization relaxation. In this work, the
+contribution of TMS was characterized by in-plane angular dependent
+ferromagnetic resonance (FMR). It is demonstrated that the intrinsic Gilbert
+damping is isotropic and invariant, while the extrinsic mechanism related to
+TMS is anisotropic and can be tuned by oblique deposition. Furthermore, the two
+and fourfold TMS related to the uniaxial magnetic anisotropy (UMA) and
+magnetocrystalline anisotropy were discussed. Our results open an avenue to
+manipulate magnetization relaxation in spintronic devices.",1911.00728v1
+2020-02-26,Extreme narrow magnetic domain walls in U ferromagnets: The UCoGa case,"Surface magnetic domains of a UCoGa single crystal during
+magnetization/demagnetization processes in increasing/decreasing magnetic
+fields were investigated by means of magnetic-force-microscopy (MFM) images at
+low temperatures. The observed domain structure is typical for a ferromagnet
+with strong uniaxial anisotropy. The evolution of magnetic domains during
+cooling of the crystal below TC has also been manifested by MFM images.
+Analysis of the available data reveals that the high uniaxial
+magnetocrystalline energy in combination with the relatively small
+ferromagnetic exchange interaction in UCoGa gives rise to the formation of very
+narrow domain walls formed by the pairs of the nearest U neighbor ions with
+antiparallel magnetic moments within the basal plane. Since the very high
+anisotropy energy is a common feature of the majority of the uniaxial U
+ferromagnets, analogous domain-wall properties are expected for all these
+materials.",2002.11517v1
+2020-05-02,Lorentz microscopy and small-angle electron diffraction study of magnetic textures in La$_{1-x}$Sr$_x$MnO$_3$ (0.15 $< x <$ 0.30): the role of magnetic anisotropy,"Magnetic textures in the ferromagnetic phases of La$_{1-x}$Sr$_x$MnO$_3$ for
+0.15 $< x <$ 0.30 have been investigated by Lorentz microscopy combined with
+small-angle electron diffraction experiments. Various types of magnetic
+textures characterized by stripe, plate-shaped, and cylindrical (magnetic
+bubble) domains were found. Two distinct types of magnetic stripe domains
+appeared in the orthorhombic structure with an inversion symmetry of
+La$_{0.825}$Sr$_{0.175}$MnO$_3$, depending significantly on magnetocrystalline
+anisotropy. Based on in-situ observations as functions of temperature and the
+strength of the external magnetic field, a magnetic field-temperature phase
+diagram was constructed, showing the stabilization of magnetic bubbles in the
+ferromagnetic phase of La$_{0.825}$Sr$_{0.175}$MnO$_3$.",2005.00720v1
+2020-05-10,Anisotropic Magnetocaloric Properties of The Ludwigite Single Crystal Cu2MnBO5,"We present the results of a thorough study of the specific heat and
+magnetocaloric properties of a ludwigite crystal Cu2MnBO5 over a temperature
+range of 60 - 350 K and in magnetic fields up to 18 kOe. It is found that at
+temperatures below the Curie temperature (92 K), capacity possesses a linear
+temperature-dependent behavior, which is associated with the predominance of
+two-dimensional antiferromagnetic interactions of magnons. The temperature
+independence of capacity is observed in the temperature range of 95 - 160 K,
+which can be attributed to the excitation of the Wigner glass phase. The
+magnetocaloric effect (i.e. the adiabatic temperature change) was assessed
+through a direct measurement or an indirect method using the capacity data.
+Owing to its strong magnetocrystalline anisotropy, an anisotropic MCE or the
+rotating MCE is observed in Cu2MnBO5. A deep minimum in the rotating MCE near
+the TC is observed and may be associated with the anisotropy of the
+paramagnetic susceptibility.",2005.04572v1
+2020-11-10,Spin-waves in the collinear antiferromagnetic phase of Mn$_\bf{5}$Si$_\bf{3}$,"By combining two independent approaches, inelastic neutron scattering
+measurements and density functional theory calculations, we study the
+spin-waves in the high-temperature collinear antiferromagnetic phase (AFM2) of
+Mn$_5$Si$_3$. We obtain its magnetic ground-state properties and electronic
+structure. This study allowed us to determine the dominant magnetic exchange
+interactions and magnetocrystalline anisotropy in the AFM2 phase of
+Mn$_5$Si$_3$. Moreover, the evolution of the spin excitation spectrum is
+investigated under the influence of an external magnetic field perpendicular to
+the anisotropy easy-axis. The low energy magnon modes show a different magnetic
+field dependence which is a direct consequence of their different precessional
+nature. Finally, possible effects related to the Dzyaloshinskii-Moriya
+interaction are also considered.",2011.05455v3
+2021-04-03,"Predicting synthesizable cobalt and manganese silicides, germanide with desirable magnetic anisotropy energy","The nanoparticle Co3Si (P63/mmc) displays remarkable magnetism [Appl. Phys.
+Lett. 108, 152406 (2016)], we thus searched cobalt silicides and several phases
+are searched including a Cmcm with 60 meV/atom lower than that of P63/mmc. A
+lower-energy Co R3m (-7.03 eV/atom) is predicted, whose energy is higher than
+that of known P63/mmc (-7.04 eV/atom) but is lower than that of Fm3m (-7.02
+eV/atom). Three small-magnetism low-energy Fe5Si3 structures are searched with
+energies 30 meV/atom lower than that of experimental P63/mcm. The strong
+lattice shape dependence of magnetocrystalline anisotropy energy (MAE) is
+studied through X5Si3 (X=Mn, Fe, Co). The building-block shape and energy order
+of cobalt silicide is dominated by Co P63/mmc, Fm3m , R3m , respectively. The
+Co3C and Co3Sn have positive formation of energy, thus only Co3Ge has similar
+structures with those of counterparts of Co3Si. Several low-energy perfect or
+nearly-perfect easy-axis/plane MAE Mn3Si, Mn5Si2, and Mn5Si3 structures are
+searched and present important application, as is also the case in
+Ge-containing counterparts. A structure I4122 with energy 300 meV/atom lower
+than that of experimental Mn5Si3 P63/mcm is searched",2104.01333v2
+2021-05-19,Experimental Evidence of a change of Exchange Anisotropy Sign with Temperature in Zn-Substituted Cu2OSeO3,"We report small-angle neutron scattering from the conical state in a single
+crystal of Zn-substituted Cu2OSeO3. Using a 3D vector-field magnet to reorient
+the conical wavevector, our measurements show that the magnitude of the conical
+wavevector changes as a function of crystallographic direction. These changes
+are caused by the anisotropic exchange interaction (AEI), whose magnitude
+transitions from a maxima to a minima along the <111> and <100>
+crystallographic directions respectively. We further find that the AEI constant
+undergoes a change of sign from positive to negative with decreasing
+temperature. Unlike in the related compound FeGe, where similar behaviour of
+the AEI induces a reorientation of the helical wavevector, we show that the
+zero field helical wavevector in (Cu0.98Zn0.02)2OSeO3 remains along the <100>
+directions at all temperatures due to the competing fourth-order
+magnetocrystalline anisotropy becoming dominant at lower temperatures.",2105.09273v1
+2021-06-17,Computational Optimization of MnBi to Enhance Energy Product,"High energy density magnets are preferred over induction magnets for many
+applications, including electric motors used in flying rovers, electric
+vehicles, and wind turbines. However, several issues related to cost and supply
+with state-of-the-art rare-earth-based magnet necessities development of
+high-flux magnets containing low cost, earth-abundant materials. Here, we
+demonstrate the possibility of tuning magnetization and magnetocrystalline
+anisotropy of one of the candidate materials, MnBi, by alloying it with foreign
+elements. By using the density functional theory in the high-throughput
+fashion, we consider the possibility of alloying MnBi with all possible metal
+and non-metal elements in the periodic table and found that MnBi-based alloys
+with Pd, Pt, Rh, Li, and O are stable against decomposition to constituent
+elements and have larger magnetization, energy product compared and magnetic
+anisotropy compared to MnBi We consider the possibility of these elements
+occupying half and all of the available empty sites. Combined with other
+favorable properties of MnBi, such as high Curie temperature and earth
+abundancy of constituents elements, we envision the possibility of MnBi-based
+high-energy-density magnets.",2106.09631v1
+2021-08-25,$\textit{Ab initio}$ theory of magnetism in two-dimensional $1T$-TaS$_2$,"We investigate, using a first-principles density-functional methodology, the
+nature of magnetism in monolayer $1T$-phase of tantalum disulfide ($1T$-TaS$_2$
+). Magnetism in the insulating phase of TaS$_2$ is a longstanding puzzle and
+has led to a variety of theoretical proposals including notably the realization
+of a two-dimensional quantum-spin-liquid phase. By means of non-collinear spin
+calculations, we derive $\textit{ab initio}$ spin Hamiltonians including
+two-spin bilinear Heisenberg exchange, as well as biquadratic and four-spin
+ring-exchange couplings. We find that both quadratic and quartic interactions
+are consistently ferromagnetic, for all the functionals considered.
+Relativistic calculations predict substantial magnetocrystalline anisotropy.
+Altogether, our results suggest that this material may realize an easy-plane
+XXZ quantum ferromagnet with large anisotropy.",2108.11277v1
+2021-08-31,Antiferromagnetic Hysteresis above the Spin Flop Field,"Magnetocrystalline anisotropy is essential in the physics of antiferromagnets
+and commonly treated as a constant, not depending on an external magnetic
+field. However, we demonstrate that in CoO the anisotropy should necessarily
+depend on the magnetic field, which is shown by the spin Hall magnetoresistance
+of the CoO $|$ Pt device. Below the N\'eel temperature CoO reveals a spin-flop
+transition at 240 K at 7.0 T, above which a hysteresis in the angular
+dependence of magnetoresistance unexpectedly persists up to 30 T. This behavior
+is shown to agree with the presence of the unquenched orbital momentum, which
+can play an important role in antiferromagnetic spintronics.",2109.00093v2
+2021-09-23,The free energy of twisting spins in Mn$_3$Sn,"The magnetic free energy is usually quadratic in magnetic field and depends
+on the mutual orientation of the magnetic field and the crystalline axes. Tiny
+in magnitude, this magnetocrystalline anisotropy energy (MAE) is nevertheless
+indispensable for the existence of permanent magnets. Here, we show that in
+Mn$_3$Sn, a non-collinear antiferromagnet attracting much attention following
+the discovery of its large anomalous Hall effect, the free energy of spins has
+superquadratic components, which drive the MAE. We experimentally demonstrate
+that the thermodynamic free energy includes terms odd in magnetic field
+($\mathcal{O}(H^3)+\mathcal{O}(H^5)$) and generating sixfold and twelve-fold
+angular oscillations in the torque response. We show that they are
+quantitatively explained by theory, which can be used to quantify relevant
+energy scales (Heisenberg, Dzyaloshinskii-Moriya, Zeeman and single-ion
+anisotropy) of the system. Based on the theory, we conclude that, in contrast
+with common magnets, what drives the MAE in Mn$_3$Sn is the field-induced
+deformation of the spin texture.",2109.11122v1
+2022-03-02,Polaronic Conductivity in Cr$_2$Ge$_2$Te$_6$ Single Crystals,"Intrinsic, two-dimensional (2D) ferromagnetic semiconductors are an important
+class of materials for spin-charge conversion applications. Cr$_2$Ge$_2$Te$_6$
+retains long-range magnetic order in bilayer at cryogenic temperatures and
+shows complex magnetic interactions with considerable magnetic anisotropy.
+Here, we performed a series of structural, magnetic, X-ray scattering,
+electronic, thermal transport and first-principles calculation studies which
+reveal that localized electronic charge carriers in Cr$_2$Ge$_2$Te$_6$ are
+dressed by surrounding lattice and are involved in polaronic transport via
+hopping that is sensitive on details of magnetocrystalline anisotropy. This
+opens possibility for manipulation of charge transport in Cr$_2$Ge$_2$Te$_6$ -
+based devices by electron-phonon- and spin-orbit coupling-based tailoring of
+polaron properties.",2203.00817v1
+2022-05-06,Strain-induced Shape Anisotropy in Antiferromagnetic Structures,"We demonstrate how shape-induced strain can be used to control
+antiferromagnetic order in NiO/Pt thin films. For rectangular elements
+patterned along the easy and hard magnetocrystalline anisotropy axes of our
+film, we observe different domain structures and we identify magnetoelastic
+interactions that are distinct for different domain configurations. We
+reproduce the experimental observations by modeling the magnetoelastic
+interactions, considering spontaneous strain induced by the domain
+configuration, as well as elastic strain due to the substrate and the shape of
+the patterns. This allows us to demonstrate and explain how the variation of
+the aspect ratio of rectangular elements can be used to control the
+antiferromagnetic ground state domain configuration. Shape-dependent strain
+does not only need to be considered in the design of antiferromagnetic devices,
+but can potentially be used to tailor their properties, providing an additional
+handle to control antiferromagnets.",2205.02983v2
+2022-11-03,Magnetism in Two-Dimensional Ilmenenes: Intrinsic Order and Strong Anisotropy,"Iron ilmenene is a new two-dimensional material that has recently been
+exfoliated from the naturally-occurring iron titanate found in ilmenite ore, a
+material that is abundant on earth surface. In this work, we theoretically
+investigate the structural, electronic and magnetic properties of 2D
+transition-metal-based ilmenene-like titanates. The study of magnetic order
+reveals that these ilmenenes usually present intrinsic antiferromagnetic
+coupling between the 3d magnetic metals decorating both sides of the Ti-O
+layer. Furthermore, the ilmenenes based on late 3d brass metals, such as
+CuTiO$_3$ and ZnTiO$_3$, become ferromagnetic and spin compensated,
+respectively. Our calculations including spin-orbit coupling reveal that the
+magnetic ilmenenes have large magnetocrystalline anisotropy energies when the
+3d shell departs from being either filled or half-filled, with their spin
+orientation being out-of-plane for elements below half-filling of 3d states and
+in-plane above. These interesting magnetic properties of ilmenenes make them
+useful for future spintronic applications because they could be synthesized as
+already realized in the iron case.",2211.01732v1
+2022-11-20,Spin-wave spectra in antidot lattice with inhomogeneous perpendicular magnetocrystalline anisotropy,"Magnonic crystals are structures with periodically varied magnetic properties
+that are used to control collective spin-wave excitations. With micromagnetic
+simulations, we study spin-wave spectra in a 2D antidot lattice based on a
+multilayered thin film with perpendicular magnetic anisotropy (PMA). We show
+that the modification of the PMA near the antidot edges introduces interesting
+modifications to the spin-wave spectra, even in a fully saturated state. In
+particular, the spectra split in two types of excitations, bulk modes with
+amplitude concentrated in a homogeneous part of antidot lattice, and edge modes
+with an amplitude localized in the rims of reduced PMA at the antidot edges.
+Their dependence on the geometrical or material parameters is distinct but at
+resonance conditions fulfilled, we found strong hybridization between bulk and
+radial edge modes. Interestingly, the hybridization between the fundamental
+modes in bulk and rim is of magnetostatic origin but the exchange interactions
+determine the coupling between higher-order radial rim modes and the
+fundamental bulk mode of the antidot lattice.",2211.11002v1
+2023-06-30,Achiral dipoles on a ferromagnet can affect its magnetization direction,"We demonstrate the possibility of a coupling between the magnetization
+direction of a ferromagnet and the tilting angle of adsorbed achiral molecules.
+To illustrate the mechanism of the coupling, we analyze a minimal Stoner model
+that includes Rashba spin-orbit coupling due to the electric field on the
+surface of the ferromagnet. The proposed mechanism allows us to study magnetic
+anisotropy of the system with an extended Stoner-Wohlfarth model, and argue
+that adsorbed achiral molecules can change magnetocrystalline anisotropy of the
+substrate. Our research's aim is to motivate further experimental studies of
+the current-free chirality induced spin selectivity effect involving both
+enantiomers.",2306.17592v2
+2023-07-21,First-principles prediction of phase transition of YCo$_5$ from self-consistent phonon calculations,"Recent theoretical study has shown that the hexagonal YCo$_5$ is dynamically
+unstable and distorts into a stable orthorhombic structure. In this study, we
+show theoretically that the orthorhombic phase is energetically more stable
+than the hexagonal phase in the low-temperature region, while the phonon
+entropy stabilizes the hexagonal phase thermodynamically in the
+high-temperature region. The orthorhombic-to-hexagonal phase transition
+temperature is $\sim$165 K, which is determined using the self-consistent
+phonon calculations. We investigate the magnetocrystalline anisotropy energy
+(MAE) using the self-consistent and non-self-consistent (force theorem)
+calculations with the spin-orbit interaction (SOI) along with the Hubbard $U$
+correction. Then, we find that the orthorhombic phase has similar MAE, orbital
+moment, and its anisotropy to the hexagonal phase when the self-consistent
+calculation with the SOI is performed. Since the orthorhombic phase still gives
+magnetic properties comparable to the experiments, the orthorhombic distortion
+is potentially realized in the low-temperature region, which awaits
+experimental exploration.",2307.11304v1
+2023-10-20,Exchange-driven spin Hall effect in anisotropic ferromagnets,"Crystallographic anisotropy of the spin-dependent conductivity tensor can be
+exploited to generate transverse spin-polarized current in a ferromagnetic
+film. This ferromagnetic spin Hall effect is analogous to the spin-splitting
+effect in altermagnets and does not require spin-orbit coupling.
+First-principles screening of 41 non-cubic ferromagnets revealed that many of
+them, when grown as a single crystal with tilted crystallographic axes, can
+exhibit large spin Hall angles comparable with the best available
+spin-orbit-driven spin Hall sources. Macroscopic spin Hall effect is possible
+for uniformly magnetized ferromagnetic films grown on some low-symmetry
+substrates with epitaxial relations that prevent cancellation of contributions
+from different orientation domains. Macroscopic response is also possible for
+any substrate if magnetocrystalline anisotropy is strong enough to lock the
+magnetization to the crystallographic axes in different orientation domains.",2310.13688v2
+2024-01-05,Integrated ab initio modelling of atomic order and magnetic anisotropy for rare-earth-free magnet design: effects of alloying additions in $\mathrm{L}1_0$ FeNi,"We describe an integrated modelling approach to accelerate the search for
+novel, single-phase, multicomponent materials with high magnetocrystalline
+anisotropy (MCA). For a given system we predict the nature of atomic ordering,
+its dependence on the magnetic state, and then proceed to describe the
+consequent MCA. Crucially, within our modelling framework, the same ab initio
+description of the material's electronic structure determines both aspects. We
+demonstrate this holistic method by studying the effects of alloying additions
+in FeNi, examining systems with the general stoichiometry Fe$_4$Ni$_3X$,
+including $X = $ Pt, Pd, Al, and Co. The atomic ordering behaviour predicted on
+adding these elements, fundamental for determining a material's MCA, is rich
+and varied. Equiatomic FeNi has been reported to require ferromagnetic order to
+establish the tetragonal $\mathrm{L}1_0$ order suited for significant MCA. Our
+results show that when alloying additions are included in this material,
+annealing in an applied magnetic field and/or below a material's Curie
+temperature may also promote tetragonal order, along with an appreciable effect
+on the predicted MCA.",2401.02809v1
+2024-02-14,Manipulation of magnetic anisotropy of 2D magnetized graphene by ferroelectric In$_2$Se$_3$,"The capacity to externally manipulate magnetic properties is highly desired
+from both fundamental and technological perspectives, particularly in the
+development of magnetoelectronics and spintronics devices. Here, using
+first-principles calculations, we have demonstrated the ability of controlling
+the magnetism of magnetized graphene monolayers by interfacing them with a
+two-dimensional ferroelectric material. When the 3$d$ transition metal (TM) is
+adsorbed on the graphene monolayer, its magnetization easy axis can be flipped
+from in-plane to out-of-plane by the ferroelectric polarization reversal of
+In$_2$Se$_3$, and the magnetocrystalline anisotropy energy (MAE) can be high to
+-0.692 meV/atom when adopting the Fe atom at bridge site with downward
+polarization. This may be a universal method since the 3$d$ TM-adsorbed
+graphene has a very small MAE, which can be easily manipulated by the
+ferroelectric polarization. As a result, the inherent mechanism is analyzed by
+second variation method.",2402.09153v1
+2002-09-26,Magnetization orientation dependence of the quasiparticle spectrum and hysteresis in ferromagnetic metal nanoparticles,"We use a microscopic Slater-Koster tight-binding model with short-range
+exchange and atomic spin-orbit interactions that realistically captures generic
+features of ferromagnetic metal nanoparticles to address the mesoscopic physics
+of magnetocrystalline anisotropy and hysteresis in nanoparticle quasiparticle
+excitation spectra. Our analysis is based on qualitative arguments supported by
+self-consistent Hartree-Fock calculations for nanoparticles containing up to
+260 atoms. Calculations of the total energy as a function of magnetization
+direction demonstrate that the magnetic anisotropy per atom fluctuates by
+several percents when the number of electrons in the particle changes by one,
+even for the largest particles we consider. Contributions of individual
+orbitals to the magnetic anisotropy are characterized by a broad distribution
+with a mean more than two orders of magnitude smaller than its variance and
+with no detectable correlations between anisotropy contribution and
+quasiparticle energy. We find that the discrete quasiparticle excitation
+spectrum of a nanoparticle displays a complex non-monotonic dependence on an
+external magnetic field, with abrupt jumps when the magnetization direction is
+reversed by the field, explaining recent spectroscopic studies of magnetic
+nanoparticles. Our results suggests the existence of a broad cross-over from a
+weak spin-orbit coupling to a strong spin-orbit coupling regime, occurring over
+the range from approximately 200- to 1000-atom nanoparticles.",0209608v2
+2016-06-10,"Spin-orbit coupling control of anisotropy, ground state and frustration in 5d2 Sr2MgOsO6","The influence of spin-orbit coupling (SOC) on the physical properties of the
+5d2 system Sr2MgOsO6 is probed via a combination of magnetometry, specific heat
+measurements, elastic and inelastic neutron scattering, and density functional
+theory calculations. Although a significant degree of frustration is expected,
+we find that Sr2MgOsO6 orders in a type I antiferromagnetic structure at the
+remarkably high temperature of 108 K. The measurements presented allow for the
+first accurate quantification of the size of the magnetic moment in a 5d2
+system of 0.60(2) muB - a significantly reduced moment from the expected value
+for such a system. Furthermore, significant anisotropy is identified via a spin
+excitation gap, and we confirm by first principles calculations that SOC not
+only provides the magnetocrystalline anisotropy, but also plays a crucial role
+in determining both the ground state magnetic order and the size of the local
+moment in this compound. Through comparison to Sr2ScOsO6, it is demonstrated
+that SOC-induced anisotropy has the ability to relieve frustration in 5d2
+systems relative to their 5d3 counterparts, providing an explanation of the
+high TN found in Sr2MgOsO6.",1606.03231v1
+2016-09-09,Effect of lithographically-induced strain relaxation on the magnetic domain configuration in microfabricated epitaxially grown Fe81Ga19,"We investigate the role of lithographically-induced strain relaxation in a
+micron-scaled device fabricated from epitaxial thin films of the
+magnetostrictive alloy Fe81Ga19. The strain relaxation due to lithographic
+patterning induces a magnetic anisotropy that competes with the
+magnetocrystalline and shape induced anisotropies to play a crucial role in
+stabilising a flux-closing domain pattern. We use magnetic imaging,
+micromagnetic calculations and linear elastic modelling to investigate a region
+close to the edges of an etched structure. This highly-strained edge region has
+a significant influence on the magnetic domain configuration due to an induced
+magnetic anisotropy resulting from the inverse magnetostriction effect. We
+investigate the competition between the strain-induced and shape-induced
+anisotropy energies, and the resultant stable domain configurations, as the
+width of the bar is reduced to the nanoscale range. Understanding this
+behaviour will be important when designing hybrid magneto-electric spintronic
+devices based on highly magnetostrictive materials.",1609.02930v2
+2017-09-28,Magnetization and Anisotropy of Cobalt Ferrite Thin Films,"The magnetization of thin films of cobalt ferrite frequently falls far below
+the bulk value of 455 kAm-1, which corresponds to an inverse cation
+distribution in the spinel structure with a significant orbital moment of about
+0.6 muB that is associated with the octahedrally-coordinated Co2+ ions. The
+orbital moment is responsible for the magnetostriction and magnetocrystalline
+anisotropy, and its sensitivity to imposed strain. We have systematically
+investigated the structure and magnetism of films produced by pulsed-laser
+deposition on different substrates (TiO2, MgO, MgAl2O4, SrTiO3, LSAT, LaAlO3)
+and as a function of temperature (500-700 C) and oxygen pressure (10-4 - 10
+Pa). Magnetization at room-temperature ranges from 60 to 440 kAm-1, and
+uniaxial substrate-induced anisotropy ranges from +220 kJm-3 for films on
+deposited on MgO (100) to -2100 kJm-3 for films deposited on MgAl2O4 (100),
+where the room-temperature anisotropy field reaches 14 T. No rearrangement of
+high-spin Fe3+ and Co2+ cations on tetrahedral and octahedral sites can reduce
+the magnetization below the bulk value, but a switch from Fe3+ and Co2+ to Fe2+
+and low-spin Co3+ on octahedral sites will reduce the low-temperature
+magnetization to 120 kAm-1, and a consequent reduction of Curie temperature can
+bring the room-temperature value to near zero. Possible reasons for the
+appearance of low-spin cobalt in the thin films are discussed.
+  Keywords; Cobalt ferrite, thin films, pulsed-laser deposition, low-spin Co3+,
+strain engineering of magnetization.",1709.09965v1
+2018-03-28,Perpendicular magnetic anisotropy at the Fe/MgAl$_2$O$_4$ interface: Comparative first-principles study with Fe/MgO,"We present a theoretical study on interfacial magnetocrystalline anisotropy
+for Fe/MgAl$_2$O$_4$. This system has a very small lattice mismatch at the
+interface and therefore is suitable for realizing a fully coherent
+ferromagnet/oxide interface for magnetic tunnel junctions. On the basis of
+density functional theory, we calculate the interfacial anisotropy constant
+$K_{\rm i}$ and show that this system has interfacial perpendicular magnetic
+anisotropy (PMA) with $K_{\rm i} \approx 1.2\,{\rm mJ/m^2}$, which is a little
+bit smaller than that of Fe/MgO ($K_{\rm i} \approx$ 1.5--1.7$\,{\rm mJ/m^2}$).
+Second-order perturbation analysis with respect to the spin-orbit interaction
+clarifies that the difference in $K_{\rm i}$ between Fe/MgAl$_2$O$_4$ and
+Fe/MgO originates from the difference in contributions from spin-flip
+scattering terms at the interface. We propose that the insertion of tungsten
+layers into the interface of Fe/MgAl$_2$O$_4$ is a promising way to obtain huge
+interfacial PMA with $K_{\rm i} \gtrsim 3\,{\rm mJ/m^2}$.",1803.10428v5
+2018-06-06,High performance magnetic material with Ce and La: an alternative to Nd-Fe-B magnet,"A systematic study of magnetocrystalline anisotropy is performed for
+R(La/Ce/Nd)2Fe14B tetragonal compound with the site substitution mechanism.
+Theoretical calculation suggests the 50% doping with Ce at 4f-site can lead to
+competitive magnetic anisotropy to that of the champion magnet Nd2Fe14B.
+Electronic structure calculations are performed using the full-potential
+linearized augmented plane wave method by inclusion of the spin-orbit coupling
+and Hubbard (U) interaction in the calculation for the rare-earth elements to
+get the correct influence of the localized 4f orbitals. Detailed analysis of
+the magnetic moment and magnetic anisotropy change has been studied by
+individually inserting the La and Ce atoms at the two inequivalent sites (4g
+and 4f sites) of the 2-14-B tetragonal structure. Accurate prediction of the
+total magnetic moment with the orbital contribution in the 2-14-B structure
+shows the maximum moment for Ce2Fe14B (3.86 {\mu}B/f.u less) compared to
+Nd2Fe14B. Theoretical analysis confirms that regardless of the anti-parallel
+spin moment emerging in the Ce atom the complex structure of the Ce substituted
+compound at 4f-site gives the maximum anisotropy of 2.27 meV/cell with lowering
+the magnetic moment by 1.26 {\mu}B/f.u. compared to the Nd2Fe14B compound.",1806.01990v1
+2019-07-05,Tunability of domain structure and magnonic spectra in antidot arrays of Heusler alloy,"Materials suitable for magnonic crystals demand low magnetic damping and long
+spin wave (SW) propagation distance. In this context Co based Heusler compounds
+are ideal candidates for magnonic based applications. In this work, antidot
+arrays (with different shapes) of epitaxial
+$\mathrm{Co}_2\mathrm{Fe}_{0.4}\mathrm{Mn}_{0.6}\mathrm{Si}$ (CFMS) Heusler
+alloy thin films have been prepared using e-beam lithography and sputtering
+technique. Magneto-optic Kerr effect and ferromagnetic resonance analysis have
+confirmed the presence of dominant cubic and moderate uniaxial magnetic
+anisotropies in the thin films. Domain imaging via x-ray photoemission electron
+microscopy on the antidot arrays reveals chain like switching or correlated
+bigger domains for different shape of the antidots. Time-resolved MOKE
+microscopy has been performed to study the precessional dynamics and magnonic
+modes of the antidots with different shapes. We show that the optically induced
+spin-wave spectra in such antidot arrays can be tuned by changing the shape of
+the holes. The variation in internal field profiles, pinning energy barrier,
+and anisotropy modifies the spin-wave spectra dramatically within the antidot
+arrays with different shapes. We further show that by combining the
+magnetocrystalline anisotropy with the shape anisotropy, an extra degree of
+freedom can be achieved to control the magnonic modes in such antidot lattices.",1907.02746v1
+2021-07-28,Field tunable three-dimensional magnetic nanotextures in cobalt-nickel nanowires,"Cylindrical magnetic nanowires with large transversal magnetocrystalline
+anisotropy have been shown to sustain non-trivial magnetic configurations
+resulting from the interplay of spatial confinement, exchange, and
+anisotropies. Exploiting these peculiar 3D spin configurations and their
+solitonic inhomogeneities are prospected to improve magnetization switching in
+future spintronics, such as power-saving magnetic memory and logic
+applications. Here we employ holographic vector field electron tomography to
+reconstruct the remanent magnetic states in CoNi nanowires with 10 nm
+resolution in 3D, with a particular focus on domain walls between remanent
+states and ubiquitous real-structure effects stemming from irregular morphology
+and anisotropy variations. By tuning the applied magnetic field direction, both
+longitudinal and transverse multi-vortex states of different chiralities and
+peculiar 3D features such as shifted vortex cores are stabilized. The chiral
+domain wall between the longitudinal vortices of opposite chiralities exhibits
+a complex 3D shape characterized by a push out of the central vortex line and a
+gain in exchange and anisotropy energy. A similar complex 3D texture, including
+bent vortex lines, forms at the domain boundary between transverse-vortex
+states and longitudinal configurations. Micromagnetic simulations allow an
+understanding of the origin of the observed complex magnetic states.",2107.13201v1
+2021-11-13,Sensitive electronic correlation effects on electronic properties in ferrovalley material Janus FeClF monolayer,"The electronic correlation may have essential influence on electronic
+structures in some materials with special structure and localized orbital
+distribution. In this work, taking Janus monolayer FeClF as a concrete example,
+the correlation effects on its electronic structures are investigated by using
+generalized gradient approximation plus $U$ (GGA+$U$) approach. For
+perpendicular magnetic anisotropy (PMA), the increasing electron correlation
+effect can induce the ferrovalley (FV) to half-valley-metal (HVM) to quantum
+anomalous Hall (QAH) to HVM to FV transitions. For QAH state, there are a unit
+Chern number and a chiral edge state connecting the conduction and valence
+bands. The HVM state is at the boundary of the QAH phase, whose carriers are
+intrinsically 100\% valley polarized. With the in-plane magnetic anisotropy, no
+special QAH states and prominent valley polarization are observed. However, for
+both out-of-plane and in-plane magnetic anisotropy, sign-reversible Berry
+curvature can be observed with increasing $U$. It is found that these
+phenomenons are related with the change of $d_{xy}$/$d_{x^2-y^2}$ and $d_{z^2}$
+orbital distributions and different magnetocrystalline directions. It is also
+found that the magnetic anisotropy energy (MAE) and Curie temperature strongly
+depend on the $U$. With PMA, taking typical $U=$2.5 eV, the electron valley
+polarization can be observed with valley splitting of 109 meV, which can be
+switched by reversing the magnetization direction. The analysis and results can
+be readily extended to other nine members of monolayer FeXY (X/Y=F, Cl, Br and
+I) due to sharing the same Fe-dominated low-energy states and electronic
+correlations with FeClF monolayer.",2111.07110v1
+2019-09-10,Contributions of magnetic structure and nitrogen to perpendicular magnetocrystalline anisotropy in antiperovskite $ε$-Mn$_4$N,"To study how nitrogen contributes to perpendicular magnetocrystalline
+anisotropy (PMA) in the ferrimagnetic antiperovskite Mn$_4$N, we examined both
+the fabrication of epitaxial Mn$_4$N films with various nitrogen contents and
+first-principles density-functional calculations. Saturation magnetization
+($M_{\rm s}$) peaks of 110 mT and uniaxial PMA energy densities ($K_{\rm u}$)
+of 0.1 MJ/m$^3$ were obtained for a N$_2$ gas flow ratio ($Q$) of $\sim 10 \%$
+during sputtering deposition, suggesting nearly single-phase crystalline
+$\epsilon$-Mn$_4$N. Segregation of $\alpha$-Mn and nitrogen-deficient Mn$_4$N
+grains was observed for $Q \approx 6\%$, which was responsible for a decrease
+in the $M_{\rm s}$ and $K_{\rm u}$. The first-principles calculations revealed
+that the magnetic structure of Mn$_4$N showing PMA was ""type-B"" having a
+collinear structure, whose magnetic moments couple parallel within the c-plane
+and alternating along the c-direction. In addition, the $K_{\rm u}$ calculated
+using Mn$_{32}$N$_x$ supercells showed a strong dependence on nitrogen
+deficiency, in qualitative agreement with the experimental results. The
+second-order perturbation analysis of $K_{\rm u}$ with respect to the
+spin-orbit interaction revealed that not only spin-conserving but also
+spin-flip processes contribute significantly to the PMA in Mn$_4$N. We also
+found that both contributions decreased with increasing nitrogen deficiency,
+resulting in the reduction of $K_{\rm u}$. It was noted that the decrease in
+the spin-flip contribution occurred at the Mn atoms in face-centered sites.
+This is one of the specific PMA characteristics we found for
+antiperovskite-type Mn$_4$N.",1909.04308v3
+2021-01-26,Data-driven design of a new class of rare-earth free permanent magnets,"A new class of rare-earth-free permanent magnets is proposed. The parent
+compound of this class is Co$_3$Mn$_2$Ge, and its discovery is the result of
+first principles theory combined with experimental synthesis and
+characterisation. The theory is based on a high-throughput/data-mining search
+among materials listed in the ICSD database. From ab-initio theory of the
+defect free material it is predicted that the saturation magnetization is 1.71
+T, the uniaxial magnetocrystalline anisotropy is 1.44 MJ/m$^3$, and the Curie
+temperature is 700 K. Co$_3$Mn$_2$Ge samples were then synthesized and
+characterised with respect to structure and magnetism. The crystal structure
+was found to be the MgZn$_2$-type, with partial disorder of Co and Ge on the
+crystallographic lattice sites. From magnetization measurements a saturation
+polarization of 0.86 T at 10 K was detected, together with a uniaxial
+magnetocrystalline anisotropy constant of 1.18 MJ/m$^3$, and the Curie
+temperature of $T_{\rm C}$ = 359 K. These magnetic properties make
+Co$_3$Mn$_2$Ge a very promising material as a rare-earth free permanent magnet,
+and since we can demonstrate that magnetism depends critically on the amount of
+disorder of the Co and Ge atoms, a further improvement of the magnetism is
+possible. From the theoretical works, a substitution of Ge by neighboring
+elements suggest two other promising materials - Co$_3$Mn$_2$Al and
+Co$_3$Mn$_2$Ga. We demonstrate here that the class of compounds based on
+$T_3$Mn$_2$X (T = Co or alloys between Fe and Ni; X=Ge, Al or Ga) in the
+MgZn$_2$ structure type, form a new class of rare-earth free permanent magnets
+with very promising performance.",2101.10773v1
+2022-04-20,"The first- and second-order magneto-optical effects and intrinsically anomalous transport in 2D van der Waals layered magnets CrXY (X = S, Se, Te; Y = Cl, Br, I)","Recently, the two-dimensional magnetic semiconductor CrSBr has attracted
+considerable attention due to its excellent air-stable property and high
+magnetic critical temperature. Here, we systematically investigate the
+electronic structure, magnetocrystalline anisotropy energy, first-order
+magneto-optical effects (Kerr and Faraday effects) and second-order
+magneto-optical effects (Schafer-Hubert and Voigt effects) as well as
+intrinsically anomalous transport properties (anomalous Hall, anomalous Nernst,
+and anomalous thermal Hall effects) of two-dimensional van der Waals layered
+magnets CrXY (X = S, Se, Te; Y = Cl, Br, I) by using the first-principles
+calculations. Our results show that monolayer and bilayer CrXY (X = S, Se) are
+narrow band gap semiconductors, whereas monolayer and bilayer CrTeY are
+multi-band metals. The magnetic ground states of bilayer CrXY and the easy
+magnetization axis of monolayer and bilayer CrXY are confirmed by the
+magnetocrystalline anisotropy energy calculations. Utilizing magnetic group
+theory analysis, the first-order magneto-optical effects as well as anomalous
+Hall, anomalous Nernst, and anomalous thermal Hall effects are identified to
+exist in ferromagnetic state with out-of-plane magnetization. The second-order
+magneto-optical effects are not restricted by the above symmetry requirements,
+and therefore can arise in ferromagnetic and antiferromagnetic states with
+in-plane magnetization. The calculated results are compared with the available
+theoretical and experimental data of other two-dimensional magnets and some
+conventional ferromagnets. The present work reveals that monolayer and bilayer
+CrXY with superior magneto-optical responses and anomalous transport properties
+provide an excellent material platform for the promising applications of
+magneto-optical devices, spintronics, and spin caloritronics.",2204.09223v2
+2015-04-09,Site occupancy and magnetic properties of Al-substituted M-type strontium hexaferrite,"We use first-principles total-energy calculations based on density functional
+theory to study the site occupancy and magnetic properties of Al-substituted
+$M$-type strontium hexaferrite SrFe$_{12-x}$Al$_{x}$O$_{19}$ with $x=0.5$ and
+$x=1.0$. We find that the non-magnetic Al$^{3+}$ ions preferentially replace
+Fe$^{3+}$ ions at two of the majority spin sites, $2a$ and $12k$, eliminating
+their positive contribution to the total magnetization causing the saturation
+magnetization $M_s$ to be reduced as Al concentration $x$ is increased. Our
+formation probability analysis further provides the explanation for increased
+magnetic anisotropy field when the fraction of Al is increased. Although
+Al$^{3+}$ ions preferentially occupy the $2a$ sites at a low temperature, the
+occupation probability of the $12k$ site increases with the rise of the
+temperature. At a typical annealing temperature ($> 700\,^{\circ}{\rm C}$)
+Al$^{3+}$ ions are much more likely to occupy the $12k$ site than the $2a$
+site. Although this causes the magnetocrystalline anisotropy $K_1$ to be
+reduced slightly, the reduction in $M_s$ is much more significant. Their
+combined effect causes the anisotropy field $H_a$ to increase as the fraction
+of Al is increased, consistent with recent experimental measurements.",1504.02320v2
+2015-07-09,Validity of the Néel-Arrhenius model for highly anisotropic Co_xFe_{3-x}O_4 nanoparticles,"We report a systematic study on the structural and magnetic properties of
+Co_{x}Fe_{3-x}O_{4} magnetic nanoparticles with sizes between $5$ to $25$ nm,
+prepared by thermal decomposition of Fe(acac)_{3} and Co(acac)_{2}. The large
+magneto-crystalline anisotropy of the synthesized particles resulted in high
+blocking temperatures ($42$ K \leqq $T_B$ $\leqq 345$ K for $5 \leqq$ d $\leqq
+13$ nm ) and large coercive fields ($H_C \approxeq 1600$ kA/m for $T = 5$ K).
+The smallest particles ($<d>=5$ nm) revealed the existence of a magnetically
+hard, spin-disordered surface. The thermal dependence of static and dynamic
+magnetic properties of the whole series of samples could be explained within
+the N\'{e}el-Arrhenius relaxation framework without the need of ad-hoc
+corrections, by including the thermal dependence of the magnetocrystalline
+anisotropy constant $K_1(T)$ through the empirical Br\""{u}khatov-Kirensky
+relation. This approach provided $K_1(0)$ values very similar to the bulk
+material from either static or dynamic magnetic measurements, as well as
+realistic values for the response times ($\tau_0 \simeq 10^{-10}$ s).
+Deviations from the bulk anisotropy values found for the smallest particles
+could be qualitatively explained based on Zener\'{}s relation between $K_1(T)$
+and M(T).",1507.02711v1
+2016-12-08,Elucidating the Voltage Controlled Magnetic Anisotropy,"Voltage controlled magnetic anisotropy (VCMA) is an efficient way to
+manipulate the magnetization states in nanomagnets, promising for low-power
+spintronic applications. The underlying physical mechanism for VCMA is known to
+involve a change in the d-orbital occupation on the transition metal interface
+atoms with an applied electric field. However, a simple qualitative picture of
+how this occupation controls the magnetocrystalline anisotropy (MCA) and even
+why in certain cases the MCA has opposite sign still remains elusive. In this
+paper, we exploit a simple model of orbital populations to elucidate a number
+of features typical for the interface MCA and the effect of electric field on
+it, for 3d transition metal thin films used in magnetic tunnel junctions. We
+find that in all considered cases including the Fe (001) surface, clean
+Fe1-xCox(001)/MgO interface and oxidized Fe(001)/MgO interface, the effects of
+alloying and electric field enhance the MCA energy with electron depletion
+which is largely explained by the occupancy of the minority-spin dxz,yz
+orbitals. On the other hand, the hole doped Fe(001) exhibits an inverse VCMA,
+where the MCA enhancement is achieved when electrons are accumulated at the Fe
+(001)/MgO interface with applied electric field. In this regime we predict a
+significantly enhanced VCMA which exceeds 1pJ/Vm. Realizing this regime
+experimentally may be favorable for a practical purpose of voltage driven
+magnetization reversal.",1612.02724v1
+2018-04-27,Intrinsic permanent magnetic characteristics beyond Ce2Co17 with Ce/Co substitutions,"By understanding the small easy axis magnetocrystalline anisotropy energy
+(MAE) of hexagonal Ce2Co17, an attempt has been made to improve anisotropy and
+consequently to obtain better characteristics for a high energy permanent
+magnet via site selective substitutional doping of Ce/Co with suitable
+elements. The present calculations of the electronic and magnetic properties of
+Ce2Co17 and related substituted compounds have been performed using the full
+potential linear augmented plane wave (FPLAPW) method within the generalized
+gradient approximation (GGA). Sm-substituted compounds were simulated using
+Coulomb corrected GGA (GGA+U) to provide a better representation of energy
+bands due to the strongly correlated Sm-f electrons. The formation energies for
+all substituted compounds are found to be negative which indicate their
+structural stability. Of the substitutions, Zr substitution at the Co-dumbbell
+site enhances uniaxial anisotropy of Ce2Co17. Furthermore, Sm-substitution at
+Ce-2c sites favors incremental MAE whereas a La-substitution at both 2b- and
+2c-sites depletes the tiny MAE in Ce2Co17. These observed trends in the MAE
+have been examined in terms of contributions from various electronic states.
+Finally, Ce2Zr2Co15 and SmCeCo17 are foreseen as suitable materials for
+designing permanent magnets derived from the crystal lattice structure of
+hexagonal Ce2Co17.",1804.10310v2
+2018-08-17,Temperature Dependence of Magnetic Properties of an 18-nm-thick YIG Film Grown by Liquid Phase Epitaxy: Effect of a Pt Overlayer,"Liquid phase epitaxy of an 18 nm thick Yttrium Iron garnet (YIG) film is
+achieved. Its magnetic properties are investigated in the 100 -- 400 K
+temperature range, as well as the influence of a 3 nm thick Pt overlayer on
+them. The saturation magnetization and the magnetocrystalline cubic anisotropy
+of the bare YIG film behave similarly to bulk YIG. A damping parameter of only
+a few $10^{-4}$ is measured, together with a low inhomogeneous contribution to
+the ferromagnetic resonance linewidth. The magnetic relaxation increases upon
+decreasing temperature, which can be partly ascribed to impurity relaxation
+mechanisms. While it does not change its cubic anisotropy, the Pt capping
+strongly affects the uniaxial perpendicular anisotropy of the YIG film, in
+particular at low temperatures. The interfacial coupling in the YIG/Pt
+heterostructure is also revealed by an increase of the linewidth, which
+substantially grows by lowering the temperature.",1808.05785v2
+2019-05-16,Ultralow-loss domain wall motion driven by magnetocrystalline anisotropy gradient in antiferromagnetic nanowire,"Searching for new methods controlling antiferromagnetic (AFM) domain wall is
+one of the most important issues for AFM spintronic device operation. In this
+work, we study theoretically the domain wall motion of an AFM nanowire, driven
+by the axial anisotropy gradient generated by external electric field, allowing
+the electro control of AFM domain wall motion in the merit of ultra-low energy
+loss. The domain wall velocity depending on the anisotropy gradient magnitude
+and intrinsic material properties is simulated based on the
+Landau-Lifshitz-Gilbert equation and also deduced using the energy dissipation
+theorem. It is found that the domain wall moves at a nearly constant velocity
+for small gradient, and accelerates for large gradient due to the enlarged
+domain wall width. The domain wall mobility is independent of lattice dimension
+and types of domain wall, while it is enhanced by the Dzyaloshinskii-Moriya
+interaction. In addition, the physical mechanism for much faster AFM wall
+dynamics than ferromagnetic wall dynamics is qualitatively explained. This work
+unveils a promising strategy for controlling the AFM domain walls, benefiting
+to future AFM spintronic applications.",1905.06695v2
+2022-05-20,A feasibility analysis towards the simulation of hysteresis with spin-lattice dynamics,"We use spin-lattice dynamics simulations to study the possibility of modeling
+the magnetic hysteresis behavior of a ferromagnetic material. The temporal
+evolution of the magnetic and mechanical degrees of freedom is obtained through
+a set of two coupled Langevin equations. Hysteresis loops are calculated for
+different angles between the external field and the magnetocrystalline
+anisotropy axes. The influence of several relevant parameters is studied,
+including the field frequency, magnetic damping, magnetic anisotropy (magnitude
+and type), magnetic exchange, and system size. The role played by a moving
+lattice is also discussed. For a perfect bulk ferromagnetic system we find
+that, at low temperatures, the exchange and lattice dynamics barely affect the
+loops, while the field frequency and magnetic damping have a large effect on
+it. The influence of the anisotropy magnitude and symmetry are found to follow
+the expected behavior. We show that a careful choice of simulation parameters
+allows for an excellent agreement between the spin-lattice dynamics
+measurements and the paradigmatic Stoner-Wohlfarth model. Furthermore, we
+extend this analysis to intermediate and high temperatures for the perfect bulk
+system and for spherical nanoparticles, with and without defects, reaching
+values close to the Curie temperature. In this temperature range, we find that
+lattice dynamics has a greater role on the magnetic behavior, especially in the
+evolution of the defective samples. The present study opens the possibility for
+more accurate inclusion of lattice defects and thermal effects in hysteresis
+simulations",2205.10418v3
+2022-08-13,"2D-XY ferromagnetism with high transition temperature in Janus monolayer V$_{2}$XN (X = P, As)","Two-dimensional (2D) XY magnets with easy magnetization planes support the
+nontrivial topological spin textures whose dissipationless transport is highly
+desirable for 2D spintronic devices. Here, we predicted that Janus monolayer
+V$_{2}$XN (X = P, As) with a square lattice are 2D-XY ferromagnets by
+first-principles calculations. Both the magnetocrystalline anisotropy and
+magnetic shape anisotropy favor an in-plane magnetization, leading to an easy
+magnetization $xy$-plane in Janus monolayer V$_{2}$XN. Resting on the Monte
+Carlo simulations, we observed the Berezinskii-Kosterlitz-Thouless (BKT) phase
+transition in monolayer V$_{2}$XN with transition temperature $T_{\rm BKT}$
+being above the room temperature. Especially, monolayer V$_{2}$AsN has a
+magnetic anisotropy energy (MAE) of 292.0 $\mu$eV per V atom and a $T_{\rm
+BKT}$ of 434 K, which is larger than that of monolayer V$_{2}$PN. Moreover, a
+tensile strain of 5\% can further improve the $T_{\rm BKT}$ of monolayer
+V$_{2}$XN to be above 500 K. Our results indicated that Janus monolayer
+V$_{2}$XN (X = P, As) were candidate materials to realize high-temperature
+2D-XY ferromagnetism for spintronics applications.",2208.06745v2
+2023-08-08,Giant magnetic and optical anisotropy in cerium-substituted M-type strontium hexaferrite driven by 4$f$ electrons,"By performing density functional calculations, we find a giant
+magnetocrystalline anisotropy (MCA) constant in abundant element cerium (Ce)
+substituted M-type hexaferrite, in the energetically favorable strontium site,
+assisted by a quantum confined electron transfer from Ce to specific iron (2a)
+site. Remarkably, the calculated electronic structure shows that the electron
+transfer leads to the formation of Ce$^{3+}$ and Fe$^{2+}$ at the $2a$ site
+producing an occupied Ce($4f^1$) state below the Fermi level that adds a
+significant contribution to MCA and magnetic moment. A half Ce-substitution
+forms a metallic state, while a full substitution retains the semiconducting
+state of the strontium-hexaferrite (host). In the latter, the band gap is
+reduced due to the formation of charge transferred states in the gap region of
+the host. The optical absorption coefficient shows an enhanced anisotropy
+between light polarization in parallel and perpendicular directions. Calculated
+formation energies, including the analysis of probable competing phases, and
+elastic constants confirm that both compositions are chemically and
+mechanically stable. With successful synthesis, the Ce-hexaferrite can be a new
+high-performing critical-element-free permanent magnet material adapted for use
+in devices such as automotive traction drive motors.",2308.04594v2
+2024-02-15,Dimension-Dependent Critical Scaling Analysis and Emergent Competing Interaction Scales in a 2D Van der Waals magnet Cr$_{2}$Ge$_{2}$Te$_{6}$,"We investigate thickness-dependent transformation from a paramagnetic to
+ferromagnetic phase in Cr$_{2}$Ge$_{2}$Te$_{6}$ (CGT) in bulk and few-layer
+flake forms. 2D Ising-like critical transition in bulk CGT occurs at $T_{c}$ =
+67 K with out-of-plane magnetic anisotropy. Few-layer CGT on hBN/SiO$_{2}$/Si
+substrate displays the same $T_{c}$ but also exhibits a new critical transition
+at $T^{\prime}_c$ = 14.2 K. Here, critical scaling analysis reveals the
+critical exponents differ significantly from those in bulk and do not align
+with the known universality classes. Our Density Functional Theory (DFT) and
+classical calculations indicate competition between magnetocrystalline and
+dipolar anisotropy emerges with reduced dimensions. The observed behavior is
+due to minor structural distortions in low dimensional CGT, which modify the
+balance between spin-orbit coupling, exchange interactions and dipolar
+anisotropy. This triggers a critical crossover at $T^{\prime}_c$. Our study
+shows the emergence of a complex interplay of short- and long-range
+interactions below $T^{\prime}_c$ as CGT approaches the 2D limit.",2402.09741v1
+1995-08-26,Magnetic Properties of Epitaxial and Polycrystalline Fe/Si Multilayers,"Fe/Si multilayers with antiferromagnetic interlayer coupling have been grown
+via ion-beam sputtering on both glass and single-crystal substrates. High-angle
+x-ray diffraction measurements show that both sets of films have narrow Fe
+peaks, implying a large crystallite size and crystalline iron silicide spacer
+layers. Low-angle x-ray diffraction measurements show that films grown on glass
+have rougher interfaces than those grown on single-crystal substrates. The
+multilayers grown on glass have a larger remanent magnetization than the
+multilayers grown on single-crystal substrates. The observation of
+magnetocrystalline anisotropy in hysteresis loops and $(hkl)$ peaks in x-ray
+diffraction demonstrates that the films grown on MgO and Ge are epitaxial. The
+smaller remanent magnetization in Fe/Si multilayers with better layering
+suggests that the remanence is not an intrinsic property.",9508117v1
+1997-01-07,Magnetic Field Dependence of Macroscopic Quantum Tunneling and Coherence of Ferromagnetic Particle,"We calculate the quantum tunneling rate of a ferromagnetic particle of $\sim
+100 \AA$ diameter in a magnetic field of arbitrary angle. We consider the
+magnetocrystalline anisotropy with the biaxial symmetry and that with the
+tetragonal symmetry. Using the spin-coherent-state path integral, we obtain
+approximate analytic formulas of the tunneling rates in the small $\epsilon
+(=1- H/H_c)$-limit for the magnetic field normal to the easy axis ($\theta_H =
+\pi/2$), for the field opposite to the initial easy axis ($\theta_H = \pi$),
+and for the field at an angle between these two orientations ($\pi/2 <<
+\theta_H << \pi$). In addition, we obtain numerically the tunneling rates for
+the biaxial symmetry in the full range of the angle $\theta_H$ of the magnetic
+field ($\pi/2 < \theta_H \leq \pi$), for the values of \epsilon =0.01 and
+0.001.",9701030v1
+2000-05-23,Spin tunneling of trigonal and hexagonal ferromagnets in an arbitrarily directed magnetic field,"The quantum tunneling of the magnetization vector are studied theoretically
+in single-domain ferromagnetic nanoparticles placed in an external magnetic
+field at an arbitrarily directed angle in the $ZX$ plane. We consider the
+magnetocrystalline anisotropy with trigonal and hexagonal crystal symmetry,
+respectively. By applying the instanton technique in the spin-coherent-state
+path-integral representation, we calculate the tunnel splittings, the tunneling
+rates and the crossover temperatures in the low barrier limit for different
+angle ranges of the external magnetic field ($\theta_{H}=\pi/2$,
+$\pi/2\ll\theta_{H}\ll\pi$, and $\theta_{H}=\pi$). Our results show that the
+tunnel splittings, the tunneling rates and the crossover temperatures depend on
+the orientation of the external magnetic field distinctly, which provides a
+possible experimental test for magnetic quantum tunneling in nanometer-scale
+single-domain ferromagnets.",0005373v1
+2000-05-29,Quantum nucleation in ferromagnets with tetragonal and hexagonal symmetries,"The phenomenon of quantum nucleation is studied in a ferromagnet in the
+presence of a magnetic field at an arbitrary angle. We consider the
+magnetocrystalline anisotropy with tetragonal symmetry and that with hexagonal
+symmetry, respectively. By applying the instanton method in the
+spin-coherent-state path-integral representation, we calculate the dependence
+of the rate of quantum nucleation and the crossover temperature on the
+orientation and strength of the field for a thin film and for a bulk solid. Our
+results show that the rate of quantum nucleation and the crossover temperature
+depend on the orientation of the external magnetic field distinctly, which
+provides a possible experimental test for quantum nucleation in nanometer-scale
+ferromagnets.",0005491v2
+2000-11-01,"Magnetism, Spin-Orbit Coupling, and Superconducting Pairing in UGe$_2$","A consistent picture on the mean-field level of the magnetic properties and
+electronic structure of the superconducting itinerant ferromagnet UGe$_2$ is
+shown to require inclusion of correlation effects beyond the local density
+approximation (LDA). The ""LDA+U"" approach reproduces both the magnitude of the
+observed moment, composed of strongly opposing spin and orbital parts, and the
+magnetocrystalline anisotropy. The largest Fermi surface sheet is comprised
+primarily of spin majority states with orbital projection $m_{\ell}$=0,
+suggesting a much simpler picture of the pairing than is possible for general
+strong spin-orbit coupled materials. This occurrence, and the
+quasi-two-dimensional geometry of the Fermi surface, support the likelihood of
+magnetically mediated p-wave triplet pairing.",0011026v1
+2000-11-24,Relativistic corrections in magnetic systems,"We present a weak-relativistic limit comparison between the Kohn-Sham-Dirac
+equation and its approximate form containing the exchange coupling, which is
+used in almost all relativistic codes of density-functional theory. For these
+two descriptions, an exact expression of the Dirac Green's function in terms of
+the non-relativistic Green's function is first derived and then used to
+calculate the effective Hamiltonian, i.e., Pauli Hamiltonian, and effective
+velocity operator in the weak-relativistic limit. We point out that, besides
+neglecting orbital magnetism effects, the approximate Kohn-Sham-Dirac equation
+also gives relativistic corrections which differ from those of the exact
+Kohn-Sham-Dirac equation. These differences have quite serious consequences: in
+particular, the magnetocrystalline anisotropy of an uniaxial ferromagnet and
+the anisotropic magnetoresistance of a cubic ferromagnet are found from the
+approximate Kohn-Sham-Dirac equation to be of order $1/c^2$, whereas the
+correct results obtained from the exact Kohn-Sham-Dirac equation are of order
+$1/c^4$ . We give a qualitative estimate of the order of magnitude of these
+spurious terms.",0011426v3
+2002-01-22,Magnetocrystalline Anisotropy in a Single Crystal of CeNiGe2,"We report measurements on single crystals of orthorhombic CeNiGe2, which is
+found to exhibit highly anisotropic magnetic and transport properties. The
+magnetization ratio M(H//b)/M(H^b) at 2 K is observed to be about 18 at 4 T and
+the electrical resistivity ratio r//b/r^b is about 70 at room temperature. It
+is confirmed that CeNiGe2 undergoes two-step antiferromagnetic transition at 4
+and 3 K, as reported for polycrystalline samples. The application of magnetic
+field along the b axis (the easy magnetization axis) stabilizes a ferromagnetic
+correlation between the Ce ions and enhances the hopping of carriers. This
+results in large negative magnetoresistance along the b axis.",0201399v1
+2002-01-23,Spin tunneling properties in mesoscopic magnets: effects of a magnetic field,"The tunneling of a giant spin at excited levels is studied theoretically in
+mesoscopic magnets with a magnetic field at an arbitrary angle in the easy
+plane. Different structures of the tunneling barriers can be generated by the
+magnetocrystalline anisotropy, the magnitude and the orientation of the field.
+By calculating the nonvacuum instanton solution explicitly, we obtain the
+tunnel splittings and the tunneling rates for different angle ranges of the
+external magnetic field ($\theta_{H}=\pi/2$ and $\pi/2<\theta_{H}<\pi$). The
+temperature dependences of the decay rates are clearly shown for each case. It
+is found that the tunneling rate and the crossover temperature depend on the
+orientation of the external magnetic field. This feature can be tested with the
+use of existing experimental techniques.",0201406v1
+2003-02-20,Dynamical Nuclear Polarization by Electrical Spin Injection in Ferromagnet-Semiconductor Heterostructures,"Electrical spin injection from Fe into Al$_x$Ga$_{1-x}$As quantum well
+heterostructures is demonstrated in small (< 500 Oe) in-plane magnetic fields.
+The measurement is sensitive only to the component of the spin that precesses
+about the internal magnetic field in the semiconductor. This field is much
+larger than the applied field and depends strongly on the injection current
+density. Details of the observed hysteresis in the spin injection signal are
+reproduced in a model that incorporates the magnetocrystalline anisotropy of
+the epitaxial Fe film, spin relaxation in the semiconductor, and the dynamical
+polarization of nuclei by the injected spins.",0302391v1
+2003-11-19,Shape memory ferromagnets,"In ferromagnetic alloys with shape memory large reversible strains can be
+obtained by rearranging the martensitic domain structure by a magnetic field.
+Magnetization through displacement of domain walls is possible in the presence
+of high magnetocrystalline anisotropy, when martensitic structure rearrangement
+is energetically favorable compared to the reorientation of magnetic moments.
+In ferromagnetic Heusler alloys Ni$_{2+x}$Mn$_{1-x}$Ga the Curie temperature
+exceeds the martensitic transformation temperature. The fact that these two
+temperatures are close to room temperature offers the possibility of
+magnetically controlling the shape and size of ferromagnets in the martensitic
+state. In Ni$_{2+x}$Mn$_{1-x}$Ga single crystals, a reversible strain of $\sim
+6$% is obtained in fields of $\sim 1$ T.",0311433v1
+2005-04-19,Nature of magnetism in Ca$_3$Co$_2$O$_6$,"We find using LSDA+U band structure calculations that the novel
+one-dimensional cobaltate Ca$_3$Co$_2$O$_6$ is not a ferromagnetic half-metal
+but a Mott insulator. Both the octahedral and the trigonal Co ions are formally
+trivalent, with the octahedral being in the low-spin and the trigonal in the
+high-spin state. The inclusion of the spin-orbit coupling leads to the
+occupation of the minority-spin $d_{2}$ orbital for the unusually coordinated
+trigonal Co, producing a giant orbital moment (1.57 $\mu_{B}$). It also results
+in an anomalously large magnetocrystalline anisotropy (of order 70 meV),
+elucidating why the magnetism is highly Ising-like. The role of the oxygen
+holes, carrying an induced magnetic moment of 0.13 $\mu_{B}$ per oxygen, for
+the exchange interactions is discussed.",0504490v2
+2005-09-16,Mesoscopic Resistance Fluctuations in Cobalt Nanoparticles,"We present measurements of mesoscopic resistance fluctuations in cobalt
+nanoparticles and study how the fluctuations with bias voltage, bias
+fingerprints, respond to magnetization reversal processes. Bias fingerprints
+rearrange when domains are nucleated or annihilated. The domain-wall causes an
+electron wavefunction phase-shift of $\approx 5\pi$. The phase-shift is not
+caused by the Aharonov-Bohm effect; we explain how it arises from the
+mistracking effect, where electron spins lag in orientation with respect to the
+moments inside the domain-wall. Dephasing time in Co at $0.03K$ is short,
+$\tau_\phi\sim ps$, which we attribute to the strong magnetocrystalline
+anisotropy.",0509452v3
+2006-05-15,Domain Wall Assisted Magnetic Recording,"Using numerical and analytical micromagnetics we calculated the switching
+fields and energy barriers of the composite (exchange spring) magnetic
+recording media, which consist of layers with high and low magnetocrystalline
+anisotropy. We demonstrate that the ultimate potential of the composite media
+is realized if the interfacial domain wall fits inside the layers. The
+switching occurs via domain wall nucleation, compression in the applied field,
+de-pinning and propagation through the hard/soft interface. This domain wall
+assisted switching results in a significant reduction of the switching field
+without substantial decrease of the for thermal activation energy barrier. We
+demonstrate that the Domain Wall Assisted Magnetic Recording (DWAMR) offers up
+to a three-fold areal density gain over conventional single layer recording.",0605368v1
+2006-11-21,"Valence, spin, and orbital state of the Co ions in the one-dimensional Ca3Co2O6: an x-ray absorption and magnetic circular dichroism study","We have investigated the valence, spin, and orbital state of the Co ions in
+the one-dimensional cobaltate Ca3Co2O6 using x-ray absorption and x-ray
+magnetic circular dichroism at the Co-L2,3 edges. The Co ions at both the
+octahedral Co_oct and trigonal Co_trig sites are found to be in a 3+ state.
+  From the analysis of the dichroism we established a low-spin state for the
+Co_oct and a high-spin state with an anomalously large orbital moment of 1.7
+muB at the Co3+ trig ions. This large orbital moment along the c-axis chain and
+the unusually large magnetocrystalline anisotropy can be traced back to the
+double occupancy of the d2 orbital in trigonal crystal field.",0611545v1
+2006-11-22,Substrate effects on surface magetetism of Fe/W(110) from first principles,"Surface magnetic properties of the pseudomorphic Fe(110) monolayer on a
+W(110) substrate are investigated from first principles as a function of the
+substrate thickness (up to eight layers). Analyzing the magnetocrystalline
+anisotropy energies, we find stable (with respect to the number of substrate
+layers) in-plane easy and hard axes of magnetization along the [1[overline 1]0]
+and [001] directions, respectively, reaching a value in good agreement with
+experiment for thick substrates. Additionally, the changes to the magnetic spin
+moments and the density of the Fe d states are analyzed with respect to the
+number of substrate layers as well as with respect to the direction of
+magnetization. With respect to the number of W(110) substrate layers beneath
+the Fe(110) surface, we find that the first four substrate layers have a large
+influence on the electronic and magnetic properties of the surface. Beyond the
+fourth layer, the substrate has only marginal influence on the surface
+properties.",0611581v1
+2007-09-20,Local electronic structure and magnetic properties of LaMn0.5Co0.5O3 studied by x-ray absorption and magnetic circular dichroism spectroscopy,"We have studied the local electronic structure of LaMn0.5Co0.5O3 using
+soft-x-ray absorption spectroscopy at the Co-L_3,2 and Mn-L_3,2 edges. We found
+a high-spin Co^{2+}--Mn^{4+} valence state for samples with the optimal Curie
+temperature. We discovered that samples with lower Curie temperatures contain
+low-spin nonmagnetic Co^{3+} ions. Using soft-x-ray magnetic circular dichroism
+we established that the Co^{2+} and Mn^{4+} ions are ferromagnetically aligned.
+We revealed also that the Co^{2+} ions have a large orbital moment:
+m_orb/m_spin ~ 0.47. Together with model calculations, this suggests the
+presence of a large magnetocrystalline anisotropy in the material and predicts
+a non-trivial temperature dependence for the magnetic susceptibility.",0709.3243v2
+2008-02-12,"Domain walls in (Ga,Mn)As diluted magnetic semiconductor","We report experimental and theoretical studies of magnetic domain walls in an
+in-plane magnetized (Ga,Mn)As dilute moment ferromagnetic semiconductor. Our
+high-resolution electron holography technique provides direct images of domain
+wall magnetization profiles. The experiments are interpreted based on
+microscopic calculations of the micromagnetic parameters and
+Landau-Lifshitz-Gilbert simulations. We find that the competition of uniaxial
+and biaxial magnetocrystalline anisotropies in the film is directly reflected
+in orientation dependent wall widths, ranging from approximately 40 nm to 120
+nm. The domain walls are of the N\'eel type and evolve from near-$90^{\circ}$
+walls at low-temperatures to large angle [1$\bar{1}$0]-oriented walls and small
+angle [110]-oriented walls at higher temperatures.",0802.1574v1
+2008-02-22,"Lithographically and electrically controlled strain effects on anisotropic magnetoresistance in (Ga,Mn)As","It has been demonstrated that magnetocrystalline anisotropies in (Ga,Mn)As
+are sensitive to lattice strains as small as 10^-4 and that strain can be
+controlled by lattice parameter engineering during growth, through post growth
+lithography, and electrically by bonding the (Ga,Mn)As sample to a
+piezoelectric transducer. In this work we show that analogous effects are
+observed in crystalline components of the anisotropic magnetoresistance (AMR).
+Lithographically or electrically induced strain variations can produce
+crystalline AMR components which are larger than the crystalline AMR and a
+significant fraction of the total AMR of the unprocessed (Ga,Mn)As material. In
+these experiments we also observe new higher order terms in the
+phenomenological AMR expressions and find that strain variation effects can
+play important role in the micromagnetic and magnetotransport characteristics
+of (Ga,Mn)As lateral nanoconstrictions.",0802.3344v2
+2008-03-03,X-ray absorption and x-ray magnetic dichroism study on Ca3CoRhO6 and Ca3FeRhO6,"Using x-ray absorption spectroscopy at the Rh-L_2,3, Co-L_2,3, and Fe-L_2,3
+edges, we find a valence state of Co^2+/Rh^4+ in Ca3CoRhO6 and of Fe^3+/Rh^3+
+in Ca3FeRhO6. X-ray magnetic circular dichroism spectroscopy at the Co-L_2,3
+edge of Ca3CoRhO6 reveals a giant orbital moment of about 1.7mu_B, which can be
+attributed to the occupation of the minority-spin d_0d_2 orbital state of the
+high-spin Co^2+ (3d^7) ions in trigonal prismatic coordination. This active
+role of the spin-orbit coupling explains the strong magnetocrystalline
+anisotropy and Ising-like magnetism of Ca3CoRhO6.",0803.0293v1
+2009-02-20,Residual attractive force between superparamagnetic nanoparticles,"A superparamagnetic nanoparticle (SPN) is a nanometre-sized piece of a
+material that would, in bulk, be a permanent magnet. In the SPN the individual
+atomic spins are aligned via Pauli effects into a single giant moment that has
+easy orientations set by shape or magnetocrystalline anisotropy. Above a
+size-dependent blocking temperature $T_{b}(V,\tau_{obs})$, thermal fluctuations
+destroy the average moment by flipping the giant spin between easy orientations
+at a rate that is rapid on the scale of the observation time $\tau_{obs}$.
+  We show that, depite the vanising of the average moment, two SPNs experience
+a net attractive force of magnetic origin, analogous to the van der Waals force
+between molecules that lack a permanent electric dipole. This could be relevant
+for ferrofluids, for the clumping of SPNs used for drug delivery, and for
+ultra-dense magnetic recording media.",0902.3684v1
+2009-05-28,Tunneling anisotropic magnetoresistance in organic spin valves,"We report the observation of tunneling anisotropic magnetoresistance (TAMR)
+in an organic spin-valve-like structure with only one ferromagnetic electrode.
+The device is based on a new high mobility perylene diimide-based n-type
+organic semiconductor. The effect originates from the tunneling injection from
+the LSMO contact and can thus occur even for organic layers which are too thick
+to support the assumption of tunneling through the layer. Magnetoresistance
+measurements show a clear spin-valve signal, with the typical two step
+switching pattern caused by the magnetocrystalline anisotropy of the epitaxial
+magnetic electrode.",0905.4573v2
+2009-06-29,Adaptive modulations of martensites,"Modulated phases occur in numerous functional materials like giant
+ferroelectrics and magnetic shape memory alloys. To understand the origin of
+these phases, we review and generalize the concept of adaptive martensite. As a
+starting point, we investigate the coexistence of austenite, adaptive 14M phase
+and tetragonal martensite in Ni-Mn-Ga magnetic shape memory alloy epitaxial
+films. The modulated martensite can be constructed from nanotwinned variants of
+a tetragonal martensite phase. By combining the concept of adaptive martensite
+with branching of twin variants, we can explain key features of modulated
+phases from a microscopic view. This includes phase stability, the sequence of
+6M-10M-NM intermartensitic transitions, and magnetocrystalline anisotropy.",0906.5365v1
+2009-10-28,"Magnetocrystalline anisotropy in RAu_{2}Ge_{2} (R = La, Ce and Pr) single crystals","Anisotropic magnetic properties of single crystalline RAu_{2}Ge_{2} (R = La,
+Ce and Pr) compounds are reported. LaAu_{2}Ge_{2} exhibit a Pauli-paramagnetic
+behavior whereas CeAu_{2}Ge_{2} and PrAu_{2}Ge_{2} show an antiferromagnetic
+ordering with N\grave{e}el temperatures T_{N} = 13.5 and 9 K, respectively. The
+anisotropic magnetic response of Ce and Pr compounds establishes [001] as the
+easy axis of magnetization and a sharp spin-flip type metamagnetic transition
+is observed in the magnetic isotherms. The resistance and magnetoresistance
+behavior of these compounds, in particular LaAu_{2}Ge_{2}, indicate an
+anisotropic Fermi surface. The magnetoresistivity of CeAu_{2}Ge_{2} apparently
+reveals the presence of a residual Kondo interaction. A crystal electric field
+analysis of the anisotropic susceptibility in conjunction with the
+experimentally inferred Schottky heat capacity enables us to propose a crystal
+electric field level scheme for Ce and Pr compounds. For CeAu_{2}Ge_{2} our
+values are in excellent agreement with the previous reports on neutron
+diffraction. The heat capacity data in LaAu_{2}Ge_{2} show clearly the
+existence of Einstein contribution to the heat capacity.",0910.5310v1
+2010-11-03,Issues with J-dependence in the LSDA+U method for non-collinear magnets,"We re-examine the commonly used density functional theory plus Hubbard
+\textit{U} (DFT$+U$) method for the case of non-collinear magnets. While many
+studies neglect to explicitly include the exchange correction parameter
+\textit{J}, or consider its exact value to be unimportant, here we show that in
+the case of non-collinear magnetism calculations the \textit{J} parameter can
+strongly affect the magnetic ground state. We illustrate the strong
+\textit{J}-dependence of magnetic canting and magnetocrystalline anisotropy by
+calculating trends in the magnetic lithium orthophosphate family LiMPO$_4$ (M =
+Fe and Ni) and difluorite family MF$_2$ (M = Mn, Fe, Co and Ni). Our results
+can be readily understood by expanding the usual DFT$+U$ equations within the
+spinor scheme, in which the \textit{J} parameter acts directly on the
+off-diagonal components which determine the spin canting.",1011.0939v1
+2011-04-25,"Spin canted magnetism, decoupling of charge and spin ordering in NdNiO$_3$","We report detailed magnetization measurements on the perovskite oxide
+NdNiO$_3$. This system has a first order metal-insulator (M-I) transition at
+about 200 K which is associated with charge ordering. There is also a
+concurrent paramagnetic to antiferromagnetic spin ordering transition in the
+system. We show that the antiferromagnetic state of the nickel sublattice is
+spin canted. We also show that the concurrency of the charge ordering and spin
+ordering transitions is seen only while warming up the system from low
+temperature. The transitions are not concurrent while cooling the system
+through the M-I transition temperature. This is explained based on the fact
+that the charge ordering transition is first order while the spin ordering
+transition is continuous. In the magnetically ordered state the system exhibits
+ZFC-FC irreversibilities, as well as history-dependent magnetization and aging.
+Our analysis rules out the possibility of spin-glass or superparamagnetism and
+suggests that the irreversibilities originate from magnetocrystalline
+anisotropy and domain wall pinning.",1104.4766v2
+2011-05-09,An Energy-Efficient Bennett Clocking Scheme for 4-State Multiferroic Logic,"Nanomagnets with biaxial magnetocrystalline anisotropy have four stable
+magnetization orientations that can encode 4-state logic bits (00), (01), (11)
+and (10). Recently, a 4-state NOR gate derived from three such nanomagnets,
+interacting via dipole interaction, was proposed. Here, we devise a Bennett
+clocking scheme to propagate 4-state logic bits unidirectionally between such
+gates. The nanomagnets are assumed to be made of 2-phase strain-coupled
+magnetostrictive/piezoelectric multiferroic elements, such as nickel and lead
+zirconate titanate (PZT). A small voltage of 200 mV applied across the
+piezoelectric layer can generate enough mechanical stress in the
+magnetostrictive layer to rotate its magnetization away from one of the four
+stable orientations and implement Bennett clocking. We show that a particular
+sequence of positive and negative voltages will propagate 4-state logic bits
+unidirectionally down a chain of such multiferroic nanomagnets for logic flow.",1105.1818v1
+2011-07-29,Phase transitions in single-crystalline magnetoelectric LiCoPO4,"Specific heat, magnetic torque, and magnetization studies of LiCoPO4 olivine
+are presented. They show that an unique set of physical properties of LiCoPO4
+leads to the appearance of features characteristic of 2D Ising systems near the
+Neel temperature, T_N =21.6 K, and to the appearance of an uncommon effect of
+influence of magnetic field on the magnetocrystalline anisotropy. The latter
+effect manifests itself as a first-order transition, discovered at ~9 K,
+induced by magnetic field of 8 T. Physical nature of this transition was
+explained and a model describing experimental dependences satisfactorily was
+proposed.",1107.5960v1
+2011-08-30,Electrically tunable quantum anomalous Hall effect in 5d transition-metal adatoms on graphene,"The combination of the unique properties of graphene with spin polarization
+and magnetism for the design of new spintronic concepts and devices has been
+hampered by the small Coulomb interaction and the tiny spin-orbit coupling of
+carbon in pristine graphene. Such device concepts would take advantage of the
+control of the spin degree of freedom utilizing the widely available electric
+fields in electronics or of topological transport mechanisms such as the
+conjectured quantum anomalous Hall effect. Here we show, using first-principles
+methods, that 5d transition-metal (TM) adatoms deposited on graphene display
+remarkable magnetic properties. All considered TM adatoms possess significant
+spin moments with colossal magnetocrystalline anisotropy energies as large as
+50 meV per TM atom. We reveal that the magneto-electric response of deposited
+TM atoms is extremely strong and in some cases offers even the possibility to
+switch the spontaneous magnetization direction by a moderate external electric
+field. We predict that an electrically tunable quantum anomalous Hall effect
+can be observed in this type of hybrid materials.",1108.5915v1
+2011-09-26,Electric-field control of magnetic domain wall motion and local magnetization reversal,"Spintronic devices currently rely on magnetic switching or controlled motion
+of domain walls by an external magnetic field or spin-polarized current.
+Achieving the same degree of magnetic controllability using an electric field
+has potential advantages including enhanced functionality and low power
+consumption. Here, we report on an approach to electrically control local
+magnetic properties, including the writing and erasure of regular ferromagnetic
+domain patterns and the motion of magnetic domain walls, in multiferroic
+CoFe-BaTiO3 heterostructures. Our method is based on recurrent strain transfer
+from ferroelastic domains in ferroelectric media to continuous magnetostrictive
+films with negligible magnetocrystalline anisotropy. Optical polarization
+microscopy of both ferromagnetic and ferroelectric domain structures reveals
+that domain correlations and strong inter-ferroic domain wall pinning persist
+in an applied electric field. This leads to an unprecedented electric
+controllability over the ferromagnetic microstructure, an accomplishment that
+produces giant magnetoelectric coupling effects and opens the way to
+multiferroic spintronic devices.",1109.5514v1
+2012-12-13,"First-principles study of the structural stability of Mn3Z (Z=Ga, Sn and Ge) Heusler compounds","We investigate the structural stability and magnetic properties of cubic,
+tetragonal and hexagonal phases of Mn3Z (Z=Ga, Sn and Ge) Heusler compounds
+using first-principles density-functional theory. We propose that the cubic
+phase plays an important role as an intermediate state in the phase transition
+from the hexagonal to the tetragonal phases. Consequently, Mn3Ga and Mn3Ge
+behave differently from Mn3Sn, because the relative energies of the cubic and
+hexagonal phases are different. This result agrees with experimental
+observations from these three compounds. The weak ferromagnetism of the
+hexagonal phase and the perpendicular magnetocrystalline anisotropy of the
+tetragonal phase obtained in our calculations are also consistent with
+experiment.",1212.3144v1
+2013-04-08,Effects of alloying and strain on the magnetic properties of Fe$_{16}$N$_2$,"The electronic structure and magnetic properties of pure and doped
+{Fe$_{16}$N$_2$} systems have been studied in the local-density (LDA) and
+quasiparticle self-consistent {\emph{GW}} approximations. The {\emph{GW}}
+magnetic moment of pure {Fe$_{16}$N$_2$} is somewhat larger compared to LDA but
+not anomalously large. The effects of doping on magnetic moment and exchange
+coupling were analyzed using the coherent potential approximation. The
+theoretical Curie temperature in pure {Fe$_{16}$N$_2$} is significantly higher
+than the measured value, which is attributed to the quality of available
+samples and the interpretation of experimental results. We found that different
+Fe sites contribute very differently to the magnetocrystalline anisotropy
+energy (MAE), which offers a way to increase MAE by small additions of Co or
+Ti. MAE also increases under tetragonal strain.",1304.2428v2
+2013-04-24,Spin Resolution and Evidence for Superexchange on NiO(001) observed by Force Microscopy,"The spin order of the nickel oxide (001) surface is resolved, employing
+non-contact atomic force microscopy at 4.4 K using bulk Fe- and SmCo-tips
+mounted on a qPlus sensor that oscillates at sub-50 pm amplitudes. The
+spin-dependent signal is hardly detectable with Fe-tips. In contrast, SmCo-tips
+yield a height contrast of 1.35 pm for Ni ions with opposite spins. SmCo tips
+even show a small height contrast on the O atoms of 0.5 pm within the 2x1 spin
+unit cell, pointing to the observation of superexchange. We attribute this to
+the increased magnetocrystalline anisotropy energy of SmCo, which stabilizes
+the magnetic moment at the apex. Atomic force spectroscopy on the Ni up, Ni
+down and O lattice site reveals a magnitude of the exchange energy of merely 1
+meV at the closest accessible distance with an exponential decay length of
+\lambda_exc = 18 pm.",1304.6515v3
+2013-09-17,Tuning the Curie temperature of FeCo compounds by tetragonal distortion,"Combining density-functional theory calculations with a classical Monte Carlo
+method, we show that for B2-type FeCo compounds tetragonal distortion gives
+rise to a strong reduction of the Curie temperature $T_{\mathrm{C}}$. The
+$T_{\mathrm{C}}$ monotonically decreases from 1575 K (for $c/a=1$) to 940 K
+(for $c/a=\sqrtwo$). We find that the nearest neighbor Fe-Co exchange
+interaction is sufficient to explain the $c/a$ behavior of the
+$T_{\mathrm{C}}$. Combination of high magnetocrystalline anisotropy energy with
+a moderate $T_{\mathrm{C}}$ value suggests tetragonal FeCo grown on the Rh
+substrate with $c/a=1.24$ to be a promising material for heat-assisted magnetic
+recording applications.",1309.4232v1
+2014-02-11,Weak spin interactions in Mott insulating La2O2Fe2OSe2,"Identifying and characterizing the parent phases of iron-based
+superconductors is an important step towards understanding the mechanism for
+their high temperature superconductivity. We present an investigation into the
+magnetic interactions in the Mott insulator La2O2Fe2OSe2. This iron oxyselenide
+adopts a 2-k magnetic structure with low levels of magnetic frustration. This
+magnetic ground state is found to be dominated by next-nearest neighbor
+interactions J2 and J2' and the magnetocrystalline anisotropy of the Fe2+ site,
+leading to 2D-Ising-like spin S=2 fluctuations. In contrast to calculations,
+the values are small and confine the spin excitations below ~ 25 meV. This is
+further corroborated by sum rules of neutron scattering. This indicates that
+superconductivity in related materials may derive from a weakly coupled and
+unfrustrated magnetic structure.",1402.2684v1
+2014-07-05,Atomistic modeling of magnetization reversal modes in $L1_{0}$ FePt nanodots with magnetically soft edges,"Nanopatterned FePt nano-dots often exhibit low coercivity and a broad
+switching field distribution, which could arise due to edge damage during the
+patterning process causing a reduction in the $L1_{0}$ ordering required for a
+high magnetocrystalline anisotropy. Using an atomistic spin model, we study the
+magnetization reversal behavior of $L1_{0}$ FePt nanodots with soft magnetic
+edges. We show that reversal is initiated by nucleation for the whole range of
+edge widths studied. For narrow soft edges the individual nucleation events
+dominate reversal; for wider edges, multiple nucleation at the edge creates a
+circular domain wall at the interface which precedes complete reversal. Our
+simulations compare well with available analytical theories. The increased edge
+width further reduces and saturates the required nucleation field. The
+nucleation field and the activation volume manipulate the thermally induced
+switching field distribution. By control of the properties of dot edges using
+proper patterning methods, it should be possible to realize exchange spring bit
+patterned media without additional soft layers.",1407.1363v2
+2014-07-14,Magnetic / dielectric anomalies and magnetodielectric / magnetoelectric effects in Z- and W-type hexaferrites,"Two kinds of specimens, with the major phase of Sr3Co2Fe24O41 (Sr3Co2Z) and
+SrCo2Fe16O27 (SrCo2W) hexaferrites respectively, were fabricated through
+solid-state reaction. The phase composition, magnetic and dielectric
+properties, magnetodielectric (MD) effect, magnetoelectric (ME) effect and
+pyroelectric properties were studied. Results show that magnetic and dielectric
+anomalies are induced by the magnetocrystalline anisotropy (MCA) transition.
+They can be considered as characteristic properties (e.g., Sr3Co2Z at 370 K)
+but are not a sufficient condition for the MD and ME coupling. The T-block
+structure, existing in Sr3Co2Z but absent in SrCo2W, results in the dielectric
+response with ferroelectric (FE) and magnetic contributions.",1407.3605v2
+2014-08-04,55~Tesla coercive magnetic field in frustrated Sr$_3$NiIrO$_6$,"We have measured extremely large coercive magnetic fields of up to 55~T in
+Sr$_3$NiIrO$_6$, with a switched magnetic moment $\approx 0.8~\mu_{\rm B}$ per
+formula unit. As far as we are aware, this is the largest coercive field
+observed thus far. This extraordinarily hard magnetism has a completely
+different origin from that found in conventional ferromagnets. Instead, it is
+due to the evolution of a frustrated antiferromagnetic state in the presence of
+strong magnetocrystalline anisotropy due to the overlap of spatially-extended
+Ir$^{4+}$ 5$d$ orbitals with oxygen 2$p$ and Ni$^{2+}$ 3$d$ orbitals. This work
+highlights the unusual physics that can result from combining the extended $5d$
+orbitals in Ir$^{4+}$ with the frustrated behaviour of triangular lattice
+antiferromagnets.",1408.0758v1
+2014-10-24,Strong magnetic coupling in the hexagonal R5Pb3 compounds (R = Gd-Tm),"We have synthesized R5Pb3 (R = Gd-Tm) compounds in polycrystalline form and
+performed structural analysis, magnetization, and neutron scattering
+measurements. For all R5Pb3 reported here the Weiss temperatures {\theta}W are
+several times smaller than the ordering temperatures TORD, while the latter are
+remarkably high (TORD up to 275 K for R = Gd) compared to other known R-M
+binaries (M = Si, Ge, Sn and Sb). The magnetic order changes from ferromagnetic
+in R = Gd, Tb to antiferromagnetic in R = Dy-Tm. Below TORD, the magnetization
+measurements together with neutron powder diffraction show complex magnetic
+behavior and reveal the existence of up to three additional phase transitions.
+We believe this to be a result of crystal electric field effects responsible
+for high magnetocrystalline anisotropy. The R5Pb3 magnetic unit cells for R =
+Tb-Tm can be described with incommensurate magnetic wave vectors with spin
+modulation either along the c axis in R = Tb, Er and Tm or within the ab-plane
+in R = Dy and Ho.",1410.6732v1
+2015-04-16,Heat capacity study of the magnetic phases in a Nd$_5$Ge$_3$ single crystal,"The different magnetic phases of the intermetallic compound Nd$_5$Ge$_3$ are
+studied in terms of the specific heat, in a broad range of temperatures
+(350~mK--140~K) and magnetic fields (up to 40 kOe). The expected $T^{3}$ and
+$T^{3/2}$ terms are not found in the antiferromagnetic (AFM) and ferromagnetic
+(FM) phases respectively, but a gapped $T^2$ contribution that originates from
+a mixture of AFM and FM interactions in different dimensionalities under a
+large magnetocrystalline anisotropy, is present in both. An almost identical
+Schottky anomaly, that arises from the hyperfine splitting of the nuclear
+levels of the Nd$^{3+}$ ions, is observed in both phases, which leads us to
+state that the magnetic-field induced transition AFM$\to$FM that the system
+experiments below $26~\text{K}$ consists in the flip of the magnetic moments of
+the Nd ions, conserving the average local moment.",1504.04252v1
+2015-04-22,Structures and magnetic properties of Co-Zr-B magnets studied by first-principles calculations,"The structures and magnetic properties of the Co-Zr-B alloys near the Co5Zr
+composition were studied using adaptive genetic algorithm and first-principles
+calculations to guide further experimental effort on optimizing their magnetic
+performances. Through extensive structural searches, we constructed the contour
+maps of the energetics and magnetic moments of the Co-Zr-B magnet alloys as a
+function of composition. We found that the Co-Zr-B system exhibits the same
+structural motif as the ""Co11Zr2"" polymorphs, which plays a key role in
+achieving high coercivity. Boron atoms can either substitute selective cobalt
+atoms or occupy the interstitial sites. First-principles calculation shows that
+the magnetocrystalline anisotropy energies can be significantly improved
+through proper boron doping.",1504.05829v1
+2015-04-28,Surface-termination dependent magnetism and strong perpendicular magnetocrystalline anisotropy of a FeRh (001) thin film: A density-functional study,"Magnetism of FeRh (001) films strongly depends on film thickness and surface
+terminations. While magnetic ground state of bulk FeRh is G-type
+antiferromagnetism, the Rh-terminated films exhibit ferromagnetism with strong
+perpendicular MCA whose energy +2.1 meV/$\Box$ is two orders of magnitude
+greater than 3$d$ magnetic metals, where $\Box$ is area of two-dimensional unit
+cell. While Goodenough-Kanamori-Anderson rule on the superexchange interaction
+is crucial in determining the magnetic ground phases of FeRh bulk and thin
+films, the magnetic phases are results of interplay and competition between
+three mechanisms - the superexchange interaction, the Zener direct-interaction,
+and magnetic energy gain.",1504.07349v3
+2015-06-11,Magnetism in tetragonal manganese-rich Heusler compounds,"A comprehensive study of the total energy of manganese-rich Heusler compounds
+using density functional theory is presented. Starting from a large set of
+cubic parent systems, the response to tetragonal distortions is studied in
+detail. We single out the systems that remain cubic from those that most likely
+become tetragonal. The driving force of the tetragonal distortion and its
+effect on the magnetic properties, especially where they deviate from the
+Slater--Pauling rule, as well as the trends in the Curie temperatures, are
+highlighted. By means of partial densities of states, the electronic structural
+changes reveal the microscopic origin of the observed trends. We focus our
+attention on the magnetocrystalline anisotropy and find astonishingly high
+values for tetragonal Heusler compounds containing heavy transition metals
+accompanied by low magnetic moments, which indicates that these materials are
+promising candidates for spin-transfer torque magnetization-switching
+applications.",1506.03735v1
+2015-06-29,"Effect of Misfit Strain in (Ga,Mn)(Bi,As) Epitaxial Layers on their Magnetic and Magneto-Transport Properties","Effect of misfit strain in the layers of (Ga,Mn)(Bi,As) quaternary diluted
+magnetic semiconductor, epitaxially grown on either GaAs substrate or (In,Ga)As
+buffer, on their magnetic and magneto-transport properties has been
+investigated. High-resolution X-ray diffraction, applied to characterize the
+structural quality and misfit strain in the layers, proved that the layers were
+fully strained to the GaAs substrate or (In,Ga)As buffer under compressive or
+tensile strain, respectively. Ferromagnetic Curie temperature and
+magnetocrystalline anisotropy of the layers have been examined by using
+magneto-optical Kerr effect magnetometry and low-temperature magneto-transport
+measurements. Post-growth annealing treatment of the layers has been shown to
+enhance the hole concentration and Curie temperature in the layers.",1506.08718v1
+2015-07-27,A method for measuring the Neel relaxation time in a frozen ferrofluid,"We report a novel method of determining the average Neel relaxation time and
+its temperature dependence by calculating derivatives of the measured time
+dependence of temperature for a frozen ferrofluid exposed to an alternating
+magnetic field. The ferrofluid, composed of dextran-coated Fe3O4 nanoparticles
+(diameter 13.7 nm +/- 4.7 nm), was synthesized via wet chemical precipitation
+and characterized by x-ray diffraction and transmission electron microscopy. An
+alternating magnetic field of constant amplitude (H0 = 20 kA/m) driven at
+frequencies of 171 kHz, 232 kHz and 343 kHz was used to determine the
+temperature dependent magnetic energy absorption rate in the temperature range
+from 160 K to 210 K. We found that the specific absorption rate of the
+ferrofluid decreased monotonically with temperature over this range at the
+given frequencies. From these measured data, we determined the temperature
+dependence of the Neel relaxation time and estimate a room-temperature
+magnetocrystalline anisotropy constant of 40 kJ/m3, in agreement with
+previously published results.",1507.07471v1
+2015-09-03,Investigation of ferromagnetic domain behavior and phase transition at nanoscale in bilayer manganites,"Understanding the underlying mechanism and phenomenology of colossal
+magnetoresistance in manganites has largely focused on atomic and nanoscale
+physics such as double exchange, phase separation, and charge order. Here we
+consider a more macroscopic view of manganite materials physics, reporting on
+the ferromagnetic domain behavior in a bilayer manganite sample with a nominal
+composition of La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ with $x=0.38$, studied using
+in-situ Lorentz transmission electron microscopy. The role of
+magnetocrystalline anisotropy on the structure of domain walls was elucidated.
+On cooling, magnetic domain contrast was seen to appear first at the Curie
+temperature within the $a-b$ plane. With further reduction in temperature, the
+change in area fraction of magnetic domains was used to estimate the critical
+exponent describing the ferromagntic phase transition. The ferromagnetic phase
+transition was accompanied by a distinctive nanoscale granular contrast close
+to the Curie temperature, which we infer to be related to the presence of
+ferromagnetic nanoclusters in a paramagnetic matrix, which has not yet been
+reported in bilayer manganites.",1509.01106v1
+2015-11-06,"Structural, magnetic and electrical properties of sputter deposited Mn-Fe-Ga thin films","We investigated structural, magnetic and electrical properties of sputter
+deposited Mn-Fe-Ga compounds. The crystallinity of the Mn-Fe-Ga thin films was
+confirmed using x-ray diffraction. X-ray reflection and atomic force microscopy
+measurements were utilized to investigate the surface properties, roughness,
+thickness and density of the deposited Mn-Fe-Ga. Depending on the
+stoichiometry, as well as the used substrates (SrTiO3 (001) and MgO (001)) or
+buffer layer (TiN) the Mn-Fe-Ga crystallizes in the cubic or the tetragonally
+distorted phase. Anomalous Hall effect and alternating gradient magnetometry
+measurements confirmed strong perpendicular magnetocrystalline anisotropy. Low
+saturation magnetization and hard magnetic behavior was reached by tuning the
+composition. Temperature dependent anomalous Hall effect measurements in a
+closed cycle He-cryostat showed a slight increase in coercivity with decreasing
+temperature (300K to 2K). TiN buffered Mn2.7Fe0.3Ga revealed sharper switching
+of the magnetization compared to the unbuffered layers.",1511.02097v2
+2015-12-10,Piezomagnetic effect as a counterpart of negative thermal expansion in magnetically frustrated Mn-based antiperovskite nitrides,"Electric-field control of magnetization promises to substantially enhance the
+energy efficiency of device applications ranging from data storage to
+solid-state cooling. However, the intrinsic linear magnetoelectric effect is
+typically small in bulk materials. In thin films electric-field tuning of
+spin-orbit interaction phenomena (e.g., magnetocrystalline anisotropy) has been
+reported to achieve a partial control of the magnetic state. Here we explore
+the piezomagnetic effect (PME), driven by frustrated exchange interactions,
+which can induce a net magnetization in an antiferromagnet and reverse its
+direction via elastic strain generated piezoelectrically. Our $ab~initio$ study
+of PME in Mn-antiperovskite nitrides identified an extraordinarily large PME in
+Mn$_3$SnN available at room temperature. We explain the magnitude of PME based
+on features of the electronic structure and show an inverse-proportionality
+between the simulated zero-temperature PME and the negative thermal expansion
+at the magnetic (N\'eel) transition measured by Takenaka et al. in 9
+antiferromagnetic Mn$_3$AN systems.",1512.03470v2
+2016-04-25,Room temperature tetragonal noncollinear antiferromagnet Pt$_2$MnGa,"Here we present the tetragonal stoichiometric Heusler compound Pt$_2$MnGa
+with the noncollinear AFM order stable up to 350 K. It is resolved by the
+neutron diffraction as a helical spiral propagating along the tetragonal axis.
+Ab-initio calculations suggest a pure exchange origin of the spiral and explain
+its helical character being stabilized by a large basal plane
+magnetocrystalline anisotropy (MCA). Together with the inversion-symmetric
+crystal structure, this provides a bi-stability of a spiral with respect to the
+right- and left-handed magnetic helices. Despite the large MCA, the long period
+of a helix might greatly facilitate the switch of the helicity by the
+precessional reorientation, suggesting Pt$_2$MnGa as a potential candidate for
+the vector-helicity based non-volatile magnetic memory.",1604.07137v1
+2016-08-26,Optimization of nanocomposite materials for permanent magnets by micromagnetic simulations: effect of the intergrain exchange and the hard grains shape,"In this paper we perform the detailed numerical analysis of remagnetization
+processes in nanocomposite magnetic materials consisting of magnetically hard
+grains (i.e. grains made of a material with a high magnetocrystalline
+anisotropy) embedded into a magnetically soft phase. Such materials are widely
+used for the production of permanent magnets, because they combine the high
+remanence with the large coercivity. We perform simulations of nanocomposites
+with Sr-ferrite as the hard phase and Fe or Ni as the soft phase, concentrating
+our efforts on analyzing the effects of ({\it i}) the imperfect intergrain
+exchange and ({\it ii}) the non-spherical shape of hard grains. We demonstrate
+that - in contrast to the common belief - the maximal energy product is
+achieved not for systems with the perfect intergrain exchange, but for
+materials where this exchange is substantially weakened. We also show that the
+main parameters of the hysteresis loop - remanence, coercivity and the energy
+product - exhibit non-trivial dependencies on the shape of hard grains, and
+provide detailed explanations for our results. Simulation predictions obtained
+in this work open new ways for the optimization of materials for permanent
+magnets.",1608.07429v1
+2016-09-02,Potential Energy Driven Spin Manipulation via a Controllable Hydrogen Ligand,"Spin-bearing molecules can be stabilized on surfaces and in junctions with
+desirable properties such as a net spin that can be adjusted by external
+stimuli. Using scanning probes, initial and final spin states can be deduced
+from topographic or spectroscopic data, but how the system transitioned between
+these states is largely unknown. Here we address this question by manipulating
+the total spin of magnetic cobalt hydride complexes on a corrugated boron
+nitride surface with a hydrogen- functionalized scanning probe tip by
+simultaneously tracking force and conductance. When the additional hydrogen
+ligand is brought close to the cobalt monohydride, switching between a corre-
+lated S = 1 /2 Kondo state, where host electrons screen the magnetic moment,
+and a S = 1 state with magnetocrystalline anisotropy is observed. We show that
+the total spin changes when the system is transferred onto a new potential
+energy surface defined by the position of the hydrogen in the junction. These
+results show how and why chemically functionalized tips are an effective tool
+to manipulate adatoms and molecules, and a promising new method to selectively
+tune spin systems.",1609.00612v2
+2016-09-03,Domain structure of ultrathin ferromagnetic elements in the presence of Dzyaloshinskii-Moriya interaction,"Recent advances in nanofabrication make it possible to produce multilayer
+nanostructures composed of ultrathin film materials with thickness down to a
+few monolayers of atoms and lateral extent of several tens of nanometers. At
+these scales, ferromagnetic materials begin to exhibit unusual properties, such
+as perpendicular magnetocrystalline anisotropy and antisymmetric exchange, also
+referred to as Dzyaloshinskii-Moriya interaction (DMI), because of the
+increased importance of interfacial effects. The presence of surface DMI has
+been demonstrated to fundamentally alter the structure of domain walls. Here we
+use the micromagnetic modeling framework to analyse the existence and structure
+of chiral domain walls, viewed as minimizers of a suitable micromagnetic energy
+functional. We explicitly construct the minimizers in the one-dimensional
+setting, both for the interior and edge walls, for a broad range of parameters.
+We then use the methods of {$\Gamma$}-convergence to analyze the asymptotics of
+the two-dimensional mag- netization patterns in samples of large spatial extent
+in the presence of weak applied magnetic fields.",1609.00841v1
+2016-09-05,Critical Current Oscillations of Josephson Junctions Containing PdFe Nanomagnets,"Josephson junctions with ferromagnetic layers are vital elements in a new
+class of cryogenic memory devices. One style of memory device contains a spin
+valve with one ""hard"" magnetic layer and one ""soft"" layer. To achieve low
+switching fields, it is advantageous for the soft layer to have low
+magnetization and low magnetocrystalline anisotropy. A candidate class of
+materials that fulfills these criteria is the Pd$_{1-x}$Fe$_{x}$ alloy system
+with low Fe concentrations. We present studies of micron-scale
+elliptically-shaped Josephson junctions containing Pd$_{97}$Fe$_{3}$ layers of
+varying thickness. By applying an external magnetic field, the critical current
+of the junctions are found to follow characteristic Fraunhofer patterns. The
+maximum value of the critical current, extracted from the Fraunhofer patterns,
+oscillates as a function of the ferromagnetic barrier thickness, indicating
+transitions in the phase difference across the junction between values of zero
+and $\pi$.",1609.01330v1
+2016-12-14,"First-principles study of intersite magnetic couplings in NdFe$_{12}$ and NdFe$_{12}$X (X = B, C, N, O, F)","We present a first-principles investigation of NdFe$_{12}$ and NdFe$_{12}$X
+(X = B, C, N, O, F) crystals with the ThMn$_{12}$ structure. Intersite magnetic
+couplings in these compounds, so-called exchange couplings, are estimated by
+Liechtenstein's method. It is found that the Nd--Fe couplings are sensitive to
+the interstitial dopant X, with the Nd--Fe(8j) coupling in particular reduced
+significantly for X = N. This suggests that the magnetocrystalline anisotropy
+decays quickly with rising temperature in the X = N system although
+nitrogenation has advantages over the other dopants in terms of enhancing
+low-temperature magnetic properties. The Curie temperature is also calculated
+from the magnetic couplings by using the mean field approximation. Introduction
+of X enhances the Curie temperature, with both structural changes and chemical
+effects found to play important roles in this enhancement.",1612.04478v5
+2016-12-20,Discovery of room temperature multiferroicity and magneto-electric coupling in Fe3Se4 nanorods,"We report for the first time, that Fe3Se4 is a room temperature, type-II
+multiferroic with magnetoelectric coupling. We observed the coexistence of
+coupled ferrimagnetic and ferroelectric ordering in Fe3Se4nanorods well above
+room temperature, which is a hard magnet with large magnetocrystalline
+anisotropy. For the first time, we observed spontaneous, reversible
+ferroelectric polarization in Fe3Se4 nanorods below the magnetic Curie
+temperature. The coupling is manifested by an anomaly in the dielectric
+constant and Raman shift at Tc. We do not completely understand the origin of
+the ferroelectric ordering at this point however the simultaneous presence of
+magnetic and ferroelectric ordering at room temperature in Fe3Se4 along with
+hard magnetic properties will open new research areas for devices.",1612.06512v2
+2017-02-01,Superzone gap formation and low lying crystal electric field levels in PrPd$_2$Ge$_2$ single crystal,"The magnetocrystalline anisotropy exhibited in PrPd$_2$Ge$_2$ single crystal
+has been investigated by measuring the magnetization, magnetic susceptibility,
+electrical resistivity and heat capacity. PrPd$_2$Ge$_2$ crystallizes in the
+well known ThCr$_2$Si$_2$\--type tetragonal structure. The antiferromagnetic
+ordering is confirmed as 5.1~K with the [001]-axis as the easy axis of
+magnetization. A superzone gap formation is observed from the electrical
+resistivity measurement when the current is passed along the [001] direction.
+The crystal electric field (CEF) analysis on the magnetic susceptibility,
+magnetization and the heat capacity measurements confirms a doublet ground
+state with a relatively low over all CEF level splitting. The CEF level
+spacings and the Zeeman splitting at high fields become comparable and lead to
+metamagnetic transition at 34~T due to the CEF level crossing.",1702.00220v1
+2017-02-21,Human brain ferritin studied by muon Spin Rotation: a pilot study,"Muon Spin Rotation is employed to investigate the spin dynamics of ferritin
+proteins isolated from the brain of an Alzheimer's disease (AD) patient and of
+a healthy control, using a sample of horse-spleen ferritin as a reference. A
+model based on the N\'eel theory of superparamagnetism is developed in order to
+interpret the spin relaxation rate of the muons stopped by the core of the
+protein. Using this model, our preliminary observations show that ferritins
+from the healthy control are filled with a mineral compatible with
+ferrihydrite, while ferritins from the AD patient contain a crystalline phase
+with a larger magnetocrystalline anisotropy, possibly compatible with magnetite
+or maghemite.",1702.07222v2
+2017-03-06,"Spindynamics in the antiferromagnetic phases of the Dirac metals $A$MnBi$_2$ ($A=$ Sr, Ca)","The square Bi layers in $A$MnBi$_2$ ($A =$ Sr, Ca) host Dirac fermions which
+coexist with antiferromagnetic order on the Mn sublattice below $T_\mathrm{N} =
+290\,$K (Sr) and $270\,$K (Ca). We have measured the spin-wave dispersion in
+these materials by triple-axis neutron spectroscopy. The spectra show
+pronounced spin gaps of 10.2(2)$\,$meV (Sr) and 8.3(8)$\,$meV (Ca) and extend
+to a maximum energy transfer of 61 - 63$\,$meV. The observed spectra can be
+accurately reproduced by linear spin-wave theory from an Heisenberg effective
+spin Hamiltonian. Detailed global fits of the full magnon dispersion are used
+to determine the in-plane and inter-layer exchange parameters as well as on the
+magnetocrystalline anisotropy constant. To within experimental error we find no
+evidence that the magnetic dynamics are influenced by the Dirac fermions.",1703.01849v1
+2017-05-01,One-dimensional in-plane edge domain walls in ultrathin ferromagnetic films,"We study existence and properties of one-dimensional edge domain walls in
+ultrathin ferromagnetic films with uniaxial in-plane magnetic anisotropy. In
+these materials, the magnetization vector is constrained to lie entirely in the
+film plane, with the preferred directions dictated by the magnetocrystalline
+easy axis. We consider magnetization profiles in the vicinity of a straight
+film edge oriented at an arbitrary angle with respect to the easy axis. To
+minimize the micromagnetic energy, these profiles form transition layers in
+which the magnetization vector rotates away from the direction of the easy axis
+to align with the film edge. We prove existence of edge domain walls as
+minimizers of the appropriate one-dimensional micromagnetic energy functional
+and show that they are classical solutions of the associated Euler-Lagrange
+equation with Dirichlet boundary condition at the edge. We also perform a
+numerical study of these one-dimensional domain walls and uncover further
+properties of these domain wall profiles.",1705.00700v2
+2017-07-13,Simulation of alnico coercivity,"Micromagnetic simulations of alnico show substantial deviations from
+Stoner-Wohlfarth behavior due to the unique size and spatial distribution of
+the rod-like Fe-Co phase formed during spinodal decomposition in an external
+magnetic field. The maximum coercivity is limited by single-rod effects,
+especially deviations from ellipsoidal shape, and by interactions between the
+rods. Both the exchange interaction between connected rods and magnetostatic
+interaction between rods are considered, and the results of our calculations
+show good agreement with recent experiments. Unlike systems dominated by
+magnetocrystalline anisotropy, coercivity in alnico is highly dependent on
+size, shape, and geometric distribution of the Fe-Co phase, all factors that
+can be tuned with appropriate chemistry and thermal-magnetic annealing.",1707.04180v1
+2017-12-01,Spin waves and stability of zigzag order in the Hubbard model with spin-dependent hopping terms - Application to the honeycomb lattice compounds ${\rm Na_2 Ir O_3}$ and ${\rm α- Ru Cl_3}$,"Spin waves in the zigzag ordered state on a honeycomb lattice are
+investigated within a Hubbard model with spin-dependent hopping terms. Roles of
+the emergent Kitaev, Heisenberg, Dzyaloshinskii-Moriya, and
+symmetric-off-diagonal spin interactions are investigated on the stability of
+the zigzag order. While the DM interactions are found to destabilize the zigzag
+order, the secondary spin-dependent hopping terms (associated with structural
+distortions) are shown to strongly stabilize the zigzag order and account for
+magnetocrystalline anisotropy, easy axis, and spin wave gap. The calculated
+spin wave dispersion and energy scale are in good agreement with inelastic
+neutron scattering measurements on $\rm \alpha - RuCl_3$ and $\rm Na_2 Ir O_3$.",1712.00198v2
+2018-01-10,Quantum Theory of Rare-Earth Magnets,"Strong permanent magnets mainly consist of rare earths ($R$) and transition
+metals ($T$). The main phase of the neodymium magnet, which is the strongest
+magnet, is Nd$_2$Fe$_{14}$B. Sm$_{2}$Fe$_{17}$N$_{3}$ is another magnet
+compound having excellent magnetic properties comparable to those of
+Nd$_{2}$Fe$_{14}$B. Their large saturation magnetization, strong
+magnetocrystalline anisotropy, and high Curie temperature originate from the
+interaction between the $T$-3d electrons and $R$-4f electrons. This article
+discusses the magnetism of rare-earth magnet compounds. The basic theory and
+first-principles calculation approaches for quantitative description of the
+magnetic properties are presented, together with applications to typical
+compounds such as Nd$_2$Fe$_{14}$B, Sm$_{2}$Fe$_{17}$N$_{3}$, and the recently
+synthesized NdFe$_{12}$N.",1801.03455v1
+2018-01-12,Control of oxidation and spin state in a single-molecule junction,"The oxidation and spin state of a metal-organic molecule determine its
+chemical reactivity and magnetic properties. Here, we demonstrate the
+reversible control of the oxidation and spin state in a single Fe-porphyrin
+molecule in the force field of the tip of a scanning tunneling microscope.
+Within the regimes of half-integer and integer spin state, we can further track
+the evolution of the magnetocrystalline anisotropy. Our experimental results
+are corroborated by density functional theory and wave function theory. This
+combined analysis allows us to draw a complete picture of the molecular states
+over a large range of intramolecular deformations.",1801.04162v1
+2018-02-16,"Role of typical elements in Nd$_{2}$Fe$_{14}$$X$ ($X$ = B, C, N, O, F)","The magnetic properties and structural stability of Nd$_{2}$Fe$_{14}X$ ($X$ =
+B, C, N, O, F) are theoretically studied by first-principles calculations
+focusing on the role of $X$. We find that B reduces the magnetic moment (per
+formula unit) and magnetization (per volume) in Nd$_{2}$Fe$_{14}$B. The
+crystal-field parameter $A_2^0 \langle r^2 \rangle$ of Nd is not enhanced
+either, suggesting that B has minor roles in the uniaxial magnetocrystalline
+anisotropy of Nd. These findings are in contrast to the long-held belief that B
+works positively for the magnetic properties of Nd$_{2}$Fe$_{14}$B. As $X$
+changes from B to C, N, O and F, both the magnetic properties and stability
+vary significantly. The formation energies of Nd$_{2}$Fe$_{14}X$ and
+$\alpha$-Fe relative to that of Nd$_{2}$Fe$_{17}X$ are negative for $X$ = B and
+C, whereas they are positive when $X$ = N, O and F. This indicates that B plays
+an important role in stabilizing the Nd$_{2}$Fe$_{14}$B phase.",1802.05817v1
+2018-05-07,Revealing Controllable Anisotropic Magnetoresistance in Spin Orbit Coupled Antiferromagnet Sr2IrO4,"Antiferromagnetic spintronics actively introduces new principles of magnetic
+memory, in which the most fundamental spin-dependent phenomena, i.e.
+anisotropic magnetoresistance effects, are governed by an antiferromagnet
+instead of a ferromagnet. A general scenario of the antiferromagnetic
+anisotropic magnetoresistance effects mainly stems from the magnetocrystalline
+anisotropy related to spin-orbit coupling. Here we demonstrate magnetic field
+driven contour rotation of the fourfold anisotropic magnetoresistance in bare
+antiferromagnetic Sr2IrO4/SrTiO3 (001) thin films hosting a strong spin-orbit
+coupling induced Jeff=1/2 Mott state. Concurrently, an intriguing minimal in
+the magnetoresistance emerges. Through first principles calculations, the
+band-gap engineering due to rotation of the Ir isospins is revealed to be
+responsible for these emergent phenomena, different from the traditional
+scenario where relatively more conductive state was obtained usually when
+magnetic field was applied along the magnetic easy axis. Our findings
+demonstrate a new efficient route, i.e. via the novel Jeff=1/2 state, to
+realize controllable anisotropic magnetoresistance in antiferromagnetic
+materials.",1805.02394v1
+2018-06-16,First-principles prediction of sub-10 nm skyrmions in Pd/Fe bilayers on Rh(111),"We show that stable skyrmions with diameters of a few nanometers can emerge
+in atomic Pd/Fe bilayers on the Rh(111) surface. Based on density functional
+theory we calculate the exchange and the Dzyaloshinskii-Moriya interaction as
+well as the magnetocrystalline anisotropy energy. The later two terms are
+driven by spin-orbit coupling and significantly reduced compared to Pd/Fe
+bilayers on Ir(111) as expected since Rh and Ir are isoelectronic $4d$ and $5d$
+transition-metals. However, there is still a spin spiral ground state at zero
+magnetic field. Atomistic spin dynamics simulations show that a skyrmion phase
+occurs at small magnetic fields of $\sim$ 1 T. Skyrmion diameters amount to 2
+to 8 nm and skyrmion lifetimes are up to 1 hour at temperatures of 25 to 45 K.",1806.06234v1
+2018-06-29,Stability and magnetic properties of Fe double-layers on Ir (111),"We investigate the interplay between the structural reconstruction and the
+magnetic properties of Fe doublelayers on Ir (111)-substrate using
+first-principles calculations based on density functional theory and mapping of
+the total energies on an atomistic spin model. We show that, if a second Fe
+monolayer is deposited on Fe/Ir (111), the stacking may change from hexagonal
+close-packed to bcc (110)-like accompanied by a reduction of symmetry from
+trigonal to centered rectangular. Although the bcc-like surface has a lower
+coordination, we find that this is the structural ground state. This
+reconstruction has a major impact on the magnetic structure. We investigate in
+detail the changes in the magnetic exchange interaction, the magnetocrystalline
+anisotropy, and the Dzyaloshinskii Moriya interaction depending on the stacking
+sequence of the Fe double-layer. Based on our findings, we suggest a new
+technique to engineer Dzyaloshinskii Moriya interactions in multilayer systems
+employing symmetry considerations. The resulting anisotropic
+Dzyaloshinskii-Moriya interactions may stabilize higher-order skyrmions or
+antiskyrmions.",1806.11339v1
+2018-07-17,Extended exchange interactions stabilize long-period magnetic structures in Cr$_{1/3}$NbS$_2$,"The topologically-protected, chiral soliton lattice is a unique state of
+matter offering intriguing functionality and it may serve as a robust platform
+for storing and transporting information in future spintronics devices. While
+the monoaxial chiral magnet Cr$_{1/3}$NbS$_2$ is known to host this exotic
+state in an applied magnetic field, its detailed microscopic origin has
+remained a matter of debate. Here we work towards addressing this open question
+by measuring the spin wave spectrum of Cr$_{1/3}$NbS$_2$ over the entire
+Brillouin zone with inelastic neutron scattering. The well-defined spin wave
+modes allow us to determine the values of several microscopic interactions for
+this system. The experimental data is well-explained by a Heisenberg
+Hamiltonian with exchange constants up to third nearest neighbor and an easy
+plane magnetocrystalline anisotropy term. Our work shows that both the second
+and third nearest neighbor exchange interactions contribute to the formation of
+the helimagnetic and chiral soliton lattice states in this robust
+three-dimensional magnet.",1807.06665v1
+2018-10-01,Mediating exchange bias by Verwey transition in CoO/Fe3O4 thin film,"We report the tunability of the exchange bias effect by the first-order
+metal-insulator transition (known as the Verwey transition) of Fe3O4 in CoO (5
+nm)/Fe3O4 (40 nm)/MgO (001) thin film. In the vicinity of the Verwey
+transition, the exchange bias field is substantially enhanced because of a
+sharp increase in magnetocrystalline anisotropy constant from high-temperature
+cubic to lowtemperature monoclinic structure. Moreover, with respect to the
+Fe3O4 (40 nm)/MgO (001) thin film, the coercivity field of the CoO (5 nm)/Fe3O4
+(40 nm)/MgO (001) bilayer is greatly increased for all the temperature range,
+which would be due to the coupling between Co spins and Fe spins across the
+interface.",1810.00488v1
+2018-10-19,Ferromagnetic nodal-line metal in monolayer {\em h}-InC,"Based on first-principles calculations, we predict a new two-dimensional
+ferromagnetic material that exhibits exotic Fermi surface topology. We show
+that monolayer hexagonal indium carbide ({\em h}-InC) is thermodynamically and
+dynamically stable, and it energetically favors the ferromagnetic ordering of
+spins. The perfectly planar geometry in two dimensions, together with
+ferromagnetism, gives rise to a unique opportunity to encounter intriguing
+electronic properties, captured in the Fermi surface and band topology. We show
+that multiple nodal lines coexist in momentum space, accompanied by the
+electron and hole pockets that touch each other linearly at the nodal lines.
+Inclusion of spin-orbit coupling enriches the magnetic and electronic
+properties of {\em h}-InC. Spin-orbit coupling leads to an easy-plane type
+magnetocrystalline anisotropy, and the nodal lines can be tuned into
+topological nodal points, contingent upon the magnetization direction. Symmetry
+analysis and a tight-binding model are provided to explain the nodal structure
+of the bands. Our findings suggest {\em h}-InC as a new venue for supporting
+carbon-based magnetism and exotic band topology in two dimensions.",1810.08563v2
+2019-01-04,How to accurately determine a saturation magnetization of the sample in a ferromagnetic resonance experiment?,"The phenomenon of ferromagnetic resonance (FMR) is still being exploited for
+determining the magnetocrystalline anisotropy constants of magnetic materials.
+We show that one can also determine accurately the saturation magnetization of
+the sample using results of FMR experiments after taking into account the
+relationship between resonance frequency and curvature of the spatial
+distribution of free energy at resonance. Specifically, three examples are
+given of calculating saturation magnetization from FMR data: we use historical
+Bickford's measurements from 1950 for bulk magnetite, Liu's measurements from
+2007 for a 500 mn thin film of a weak ferromagnet (Ga, Mn)As, and Wang's
+measurements from 2014 for an ultrathin film of YIG. In all three cases, the
+magnetization values we have determined are consistent with the results of
+measurements.",1901.01207v1
+2019-01-09,Anisotropic magnetic entropy change in Cr$_2$X$_2$Te$_6$ (X = Si and Ge),"Intrinsic, two-dimensional (2D) ferromagnetic semiconductors are an important
+class of materials for spintronics applications. Cr$_2$X$_2$Te$_6$ (X = Si and
+Ge) semiconductors show 2D Ising-like ferromagnetism, which is preserved in
+few-layer devices. The maximum magnetic entropy change associated with the
+critical properties around the ferromagnetic transition for Cr$_2$Si$_2$Te$_6$
+$-\Delta S_M^{max} \sim$ 5.05 J kg$^{-1}$ K$^{-1}$ is much larger than $-\Delta
+S_M^{max} \sim$ 2.64 J kg$^{-1}$ K$^{-1}$ for Cr$_2$Ge$_2$Te$_6$ with an
+out-of-plane field change of 5 T. The rescaled $-\Delta S_M(T,H)$ curves
+collapse onto a universal curve independent of temperature and field for both
+materials. This indicates similar critical behavior and 2D Ising magnetism,
+confirming the magnetocrystalline anisotropy that could preserve the long-range
+ferromagnetism in few-layers of Cr$_2$X$_2$Te$_6$.",1901.02876v1
+2019-02-22,Strongly Enhanced Gilbert Damping in 3d Transition Metal Ferromagnet Monolayers in Contact with Topological Insulator Bi2Se3,"Engineering Gilbert damping of ferromagnetic metal films is of great
+importance to exploit and design spintronic devices that are operated with an
+ultrahigh speed. Based on scattering theory of Gilbert damping, we extend the
+torque method originally used in studies of magnetocrystalline anisotropy to
+theoretically determine Gilbert dampings of ferromagnetic metals. This method
+is utilized to investigate Gilbert dampings of 3d transition metal ferromagnet
+iron, cobalt and nickel monolayers that are contacted by the prototypical
+topological insulator Bi2Se3. Amazingly, we find that their Gilbert dampings
+are strongly enhanced by about one order in magnitude, compared with dampings
+of their bulks and free-standing monolayers, owing to the strong spin-orbit
+coupling of Bi2Se3. Our work provides an attractive route to tailoring Gilbert
+damping of ferromagnetic metallic films by putting them in contact with
+topological insulators.",1902.08700v1
+2019-02-26,Oriented Three-Dimensional Magnetic Biskyrmion in MnNiGa Bulk Crystals,"A biskyrmion consists of two bound, topologically stable skyrmion spin
+textures. These coffee-bean-shaped objects have been observed in real-space in
+thin plates using Lorentz transmission electron microscopy (LTEM). From LTEM
+imaging alone, it is not clear whether biskyrmions are surface-confined
+objects, or, analogously to skyrmions in non-centrosymmetric helimagnets,
+three-dimensional tube-like structures in bulk sample. Here, we investigate the
+biskyrmion form factor in single- and polycrystalline MnNiGa samples using
+small angle neutron scattering (SANS). We find that biskyrmions are not
+long-range ordered, not even in single-crystals. Surprisingly all of the
+disordered biskyrmions have their in-plane symmetry axis aligned along certain
+directions, governed by the magnetocrystalline anisotropy. This anisotropic
+nature of biskyrmions may be further exploited to encode information.",1902.09708v1
+2019-03-06,Isolated zero field sub-10 nm skyrmions in ultrathin Co films,"Due to their exceptional topological and dynamical properties magnetic
+skyrmions - localized stable spin structures on the nanometre scale - show
+great promise for future spintronic applications. To become technologically
+competitive, isolated skyrmions with diameters below 10 nm that are stable at
+zero magnetic field and room temperature are desired. Despite finding skyrmions
+in a wide spectrum of materials, the quest for a material with these envisioned
+properties is still ongoing. Here we report zero field isolated skyrmions with
+diameters smaller than 5 nm coexisting with 1 nm thin domain walls in Rh/Co
+atomic bilayers on the Ir(111) surface. These spin structures are characterized
+by spin-polarized scanning tunnelling microscopy and can also be detected using
+non-spin-polarized tips due to a large non-collinear magnetoresistance. We
+demonstrate that sub-10 nm skyrmions are stabilised in these ferromagnetic Co
+films at zero field due to strong frustration of exchange interaction, together
+with Dzyaloshinskii-Moriya interaction and a large magnetocrystalline
+anisotropy.",1903.02258v1
+2019-04-06,Anomalous Hall effect in antiferromagnetic/non-magnetic interfaces,"We report a combined theoretical and experimental investigation of magnetic
+proximity and Hall transport in Pt/Cr bilayers. Density functional theory
+indicates that an interfacial magnetization can be induced in the Pt layer and
+a strong magnetocrystalline anisotropy with an easy axis out of plane arises in
+the antiferromagnet. A signal ascribed to the anomalous Hall effect is detected
+and associated to the interface between Pt and Cr layers. We show that this
+effect originates from the combination of proximity-induced magnetization and a
+nontrivial topology of the band structure at the interface.",1904.03541v1
+2019-04-08,Anisotropic magnetocaloric effect in Fe$_{3-x}$GeTe$_2$,"We present a comprehensive study on anisotropic magnetocaloric porperties of
+the van der Waals weak-itinerant ferromagnet Fe$_{3-x}$GeTe$_2$ that features
+gate-tunable room-temperature ferromagnetism in few-layer device. Intrinsic
+magnetocrystalline anisotropy is observed to be temperature-dependent and most
+likely favors the long-range magnetic order in thin Fe$_{3-x}$GeTe$_2$ crsytal.
+The magnetic entropy change $-\Delta S_M$ also reveals an anisotropic
+characteristic between $H // ab$ and $H // c$, which could be well scaled into
+a universal curve. The peak value $-\Delta S_M^{max}$ of 1.20 J kg$^{-1}$
+K$^{-1}$ and the corresponding adiabatic temperature change $\Delta T_{ad}$ of
+0.66 K are deduced from heat capacity with out-of-plane field change of 5 T. By
+fitting of the field-dependent parameters of $-\Delta S_M^{max}$ and the
+relative cooling power RCP, it gives $-\Delta S_M^{max} \propto H^n$ with $n =
+0.603(6)$ and $RCP \propto H^m$ with $m = 1.20(1)$ when $H // c$. Given the
+high and tunable $T_c$, Fe$_{3-x}$GeTe$_2$ crystals are of interest for
+fabricating the heterostructure-based spintronics device.",1904.03873v2
+2019-06-10,Giant anisotropic magnetoresistance and nonvolatile memory in canted antiferromagnet Sr2IrO4,"Antiferromagnets have been generating intense interest in the spintronics
+community, owing to their intrinsic appealing properties like zero stray field
+and ultrafast spin dynamics. While the control of antiferromagnetic (AFM)
+orders has been realized by various means, applicably appreciated
+functionalities on the readout side of AFM-based devices are urgently desired.
+Here, we report the remarkably enhanced anisotropic magnetoresistance (AMR) as
+giant as ~ 160% in a simple resistor structure made of AFM Sr2IrO4 without
+auxiliary reference layer. The underlying mechanism for the giant AMR is an
+indispensable combination of atomic scale giant-MR-like effect and
+magnetocrystalline anisotropy energy, which was not accessed earlier.
+Furthermore, we demonstrate the bistable nonvolatile memory states that can be
+switched in-situ without the inconvenient heat-assisted procedure, and robustly
+preserved even at zero magnetic field, due to the modified interlayer coupling
+by 1% Ga-doping in Sr2IrO4. These findings represent a straightforward step
+toward the AFM spintronic devices.",1906.03782v1
+2019-06-18,Increased perpendicular magnetocrystalline anisotropy governed by magnetic boundary in an asymmetrically terminated FeRh(001) thin film,"Rh-terminated FeRh(001) film is known to be stable in a ferromagnetic (FM)
+state different from a G-type antiferromagnetic (G-AFM) bulk ground state,
+while an Fe-terminated FeRh(001) film has the same ground state as the bulk. In
+this paper, we investigate the magnetic properties of asymmetrically terminated
+FeRh(001) films: one surface is Fe-terminated and the other is Rh-terminated.
+Rh surface only ] (RhSO) FM state in asymmetrically terminated FeRh(001) film
+is identified to exhibit 40% increased perpendicular MCA energy as compare to
+that of the whole-layer (WL) FM state. This increased MCA energy is governed by
+Rh atom which is placed at the magnetic boundary. Since FM and G-AFM states are
+mixed up at the magnetic boundary, spin-orbit couplings which give positive
+contribution to perpendicular MCA are revealed.",1906.07566v1
+2019-07-09,"Magnetization reversal, giant exchange bias effect and magnetoresistance in oxygen vacancy ordered Sr$_{4}$Fe$_{3}$CoO$_{11}$","We report the structural, magnetic, exchange bias and magnetotransport effect
+in Sr$_{4}$Fe$_{3}$CoO$_{11}$. The material crystallizes in the orthorhombic
+$\textit{Cmmm}$ space group. It shows antiferromagnetic (G-type) transition
+(T$_{N}$ = 255 K) along with interesting temperature induced magnetization
+reversal (T$_{Comp.}$= 47 K measured at 100 Oe). The magnetic reversal can be
+elucidated considering the increased magnetocrystalline anisotropy with Co
+substitution. Magnetoresistance measurements shows an interesting crossover
+from negative to positive side at $\sim$ 100 K. The negative magnetoresistance
+reaches 80 $\%$ at 25 K in 7 T magnetic field. Giant exchange bias effect is
+observed below T$_{N}$ under field cooling condition. The origin of the
+negative magnetoresistance and giant exchange bias in this sample can be
+attributed to the magnetic frustration.",1907.03986v1
+2019-08-16,Two-dimensional magnetic semiconductors with room Curie temperatures,"We propose two-dimensional (2D) Ising-type ferromagnetic semiconductors
+TcSiTe3, TcGeSe3, and TcGeTe3 with high Curie temperatures around 200-0500 K.
+Owing to large spin-orbit couplings, the large magnetocrystalline anisotropy
+energy (MAE), large anomalous Hall conductivity, and large magneto-optical Kerr
+effect were discovered in these intriguing 2D materials. By comparing all
+possible 2D MGeTe3 materials (M = 3d, 4d, 5d transition metals), we found a
+large orbital moment around 0.5 $\mu$B per atom and a large MAE for TcGeTe3.
+The large orbital moments are revealed to be from the comparable crystal fields
+and electron correlations in these Tc-based 2D materials. The microscopic
+mechanism of the high Curie temperature is also addressed. Our findings reveal
+the unique magnetic behaviors of 2D Tc-based materials and present a family of
+2D ferromagnetic semiconductors with large MAE and Kerr rotation angles that
+would have wide applications in designing spintronic devices.",1908.05836v2
+2019-09-16,Dissipation-induced rotation of suspended ferromagnetic nanoparticles,"We report the precessional rotation of magnetically isotropic ferromagnetic
+nanoparticles in a viscous liquid that are subjected to a rotating magnetic
+field. In contrast to magnetically anisotropic nanoparticles, the rotation of
+which occurs due to coupling between the magnetic and lattice subsystems
+through magnetocrystalline anisotropy, the rotation of isotropic nanoparticles
+is induced only by magnetic dissipation processes. We propose a theory of this
+phenomenon based on a set of equations describing the deterministic magnetic
+and rotational dynamics of such particles. Neglecting inertial effects, we
+solve these equations analytically, find the magnetization and particle
+precessions in the steady state, determine the components of the particle
+angular velocity and analyze their dependence on the model parameters. The
+possibility of experimental observation of this phenomenon is also discussed.",1909.07450v2
+2019-12-07,Role of higher-order exchange interactions for skyrmion stability,"Transition-metal interfaces and multilayers are a very promising class of
+systems to realize nanometer-sized, stable magnetic skyrmions for future
+spintronic devices. For room temperature applications it is crucial to
+understand the interactions which control the stability of isolated skyrmions.
+Typically, skyrmion properties are explained by the interplay of pair-wise
+exchange interactions, the Dzyaloshinskii-Moriya interaction and the
+magnetocrystalline anisotropy energy. Here, we demonstrate that higher-order
+exchange interactions -- which have so far been neglected -- can play a key
+role for the stability of skyrmions. We use an atomistic spin model
+parametrized from first-principles and compare three different ultrathin film
+systems. We consider all fourth order exchange interactions and show that in
+particular the four-site four spin interaction has a giant effect on the energy
+barrier preventing skyrmion and antiskyrmion collapse into the ferromagnetic
+state. Our work opens new perspectives to enhance the stability of topological
+spin structures.",1912.03474v2
+2020-01-12,Magnetic Skyrmions in FePt Square-Based Nanoparticles Around Room-Temperature,"Magnetic skyrmions formed at temperatures around room temperature in
+square-based parallelepiped magnetic FePt nanoparticles with perpendicular
+magnetocrystalline anisotropy (MCA) were studied during the magnetization
+reversal using micromagnetic simulations. Finite Differences (FD) method were
+used for the solution of the Landau-Lifshitz-Gilbert equation. Magnetic
+configurations exhibiting N\'eel skyrmionic formations were detected. The
+magnetic skyrmions can be created in different systems generated by the
+variation of external field, side length and width of the squared-based
+parallelepiped magnetic nanoparticles. Micromagnetic configurations revealed a
+variety of states which include skyrmionic textures with one distinct skyrmion
+formed and being stable for a range of external fields around room-temperature.
+The size of the formed N\'eel skyrmion is calculated as a function of the
+external field, temperature, MCA and nanoparticle's geometrical characteristic
+lengths which can be adjusted to produce N\'eel type skyrmions on demand having
+diameters down to 12 nm. The micromagnetic simulations revealed that stable
+skyrmions at the temperature range 270 - 330 K can be created for FePt magnetic
+nanoparticle systems lacking of chiral interactions such as
+Dzyaloshinskii-Moriya.",2001.03902v3
+2020-05-02,Field-temperature phase diagram of magnetic bubbles spanning charge$/$orbital ordered and metallic phases in La$_{1-x}$Sr$_x$MnO$_3$ ($x = 0.125$),"We report formation of magnetic textures in the ferromagnetic (FM) phase of
+La$_{1-x}$Sr$_x$MnO$_3$ for $x =$ 0.125; these textures are magnetic bubbles,
+magnetic stripe domains, and forced FM states. In situ Lorentz microscopy (LM)
+observations show that magnetic bubbles exist in the FM insulating phase
+accompanying the formation of the charge$/$orbital ordering (CO$/$OO).
+Furthermore, stable magnetic bubbles still exist in an intermediate temperature
+region between the CO$/$OO ($T_{CO} =$ 155 K) and FM ($T_c =$ 190 K) transition
+temperatures. These magnetic bubbles are believed to originate from the
+magnetocrystalline anisotropy and the dipole-dipole interaction in the FM
+phase. Based on in situ LM observations as a function of both temperature and
+the strength of the external magnetic field applied, a magnetic
+field-temperature phase diagram is constructed, exhibiting the stabilizing
+regions of the magnetic bubbles in the FM phase of
+La$_{0.875}$Sr$_{0.125}$MnO$_{3}$.",2005.00716v1
+2020-07-15,Anisotropic magnetocaloric effect and critical behavior in CrSbSe$_3$,"We report anisotropic magnetocaloric effect and critical behavior in
+quasi-one-dimensional ferromagnetic CrSbSe$_3$ single crystal. The maximum
+magnetic entropy change $-\Delta S_M^{max}$ is 2.16 J kg$^{-1}$ K$^{-1}$ for
+easy $a$ axis (2.03 J kg$^{-1}$ K$^{-1}$ for hard $b$ axis) and the relative
+cooling power $RCP$ is 163.1 J kg$^{-1}$ for easy $a$ axis (142.1 J kg$^{-1}$
+for hard $b$ axis) near $T_c$ with a magnetic field change of 50 kOe. The
+magnetocrystalline anisotropy constant $K_u$ is estimated to be 148.5 kJ
+m$^{-3}$ at 10 K, decreasing to 39.4 kJ m$^{-3}$ at 70 K. The rescaled $\Delta
+S_M(T,H)$ curves along all three axes collapse onto a universal curve,
+respectively, confirming the second order ferromagnetic transition. Further
+critical behavior analysis around $T_c \sim$ 70 K gives that the critical
+exponents $\beta$ = 0.26(1), $\gamma$ = 1.32(2), and $\delta$ = 6.17(9) for
+$H\parallel a$, while $\beta$ = 0.28(2), $\gamma$ = 1.02(1), and $\delta$ =
+4.14(16) for $H\parallel b$. The determined critical exponents suggest that the
+anisotropic magnetic coupling in CrSbSe$_3$ is strongly dependent on
+orientations of the applied magnetic field.",2007.08624v1
+2020-08-03,Experimental evidence of hidden spin polarization in silicon by using strain gradient,"The centrosymmetric materials with hidden spin polarization are considered to
+be the promising candidates for realization of energy efficient spintronics
+systems and devices. However, the control of hidden spin polarization and
+resulting transport behavior is not well understood. We hypothesized that
+inhomogeneous strain can be the external knob to study and control hidden spin
+polarization. In this work, we demonstrate a strain gradient mediated symmetry
+breaking to discover the hidden spin polarization in centrosymmetric Si
+lattice. The hidden spin polarization gives rise to magnetocrystalline
+anisotropy and local magnetic moment along <111> directions in the Si. The
+local magnetic moment gives rise to spin-acoustic phonon coupling, which is the
+underlying cause of observed spin-Hall effect in both n-Si and p-Si. Discovery
+of hidden magnetic moment in Si not only challenges the fundamental
+understanding of the origin of the magnetism but also presents a giant leap in
+realization of spintronics systems.",2008.01033v3
+2020-08-12,Prediction on Properties of Rare-earth 2-17-X Magnets Ce2Fe17-xCoxCN : A Combined Machine-learning and Ab-initio Study,"We employ a combination of machine learning and first-principles calculations
+to predict magnetic properties of rare-earth lean magnets. For this purpose,
+based on training set constructed out of experimental data, the machine is
+trained to make predictions on magnetic transition temperature (Tc), largeness
+of saturation magnetization ({\mu}0Ms), and nature of the magnetocrystalline
+anisotropy (Ku). Subsequently, the quantitative values of {\mu}0Ms and Ku of
+the yet-to-be synthesized compounds, screened by machine learning, are
+calculated by first-principles density functional theory. The applicability of
+the proposed technique of combined machine learning and first-principles
+calculations is demonstrated on 2-17-X magnets, Ce2Fe17-xCoxCN. Further to this
+study, we explore stability of the proposed compounds by calculating vacancy
+formation energy of small atom interstitials (N/C). Our study indicates a
+number of compounds in the proposed family, offers the possibility to become
+solution of cheap, and efficient permanent magnet.",2008.05125v1
+2020-09-03,MAELAS: MAgneto-ELAStic properties calculation via computational high-throughput approach,"In this work, we present the program MAELAS to calculate magnetocrystalline
+anisotropy energy, anisotropic magnetostrictive coefficients and magnetoelastic
+constants in an automated way by Density Functional Theory calculations. The
+program is based on the length optimization of the unit cell proposed by Wu and
+Freeman to calculate the magnetostrictive coefficients for cubic crystals. In
+addition to cubic crystals, this method is also implemented and generalized for
+other types of crystals that may be of interest in the study of
+magnetostrictive materials. As a benchmark, some tests are shown for well-known
+magnetic materials.",2009.01638v3
+2020-09-28,Electronic and magnetic characterization of epitaxial CrBr$_3$ monolayers,"The ability to imprint a given material property to another through proximity
+effect in layered two-dimensional materials has opened the way to the creation
+of designer materials. Here, we use molecular-beam epitaxy (MBE) for a direct
+synthesis of a superconductor-magnet hybrid heterostructure by combining
+superconducting niobium diselenide (NbSe$_2$) with the monolayer ferromagnetic
+chromium tribromide (CrBr$_3$). Using different characterization techniques and
+density-functional theory (DFT) calculations, we have confirmed that the
+CrBr$_3$ monolayer retains its ferromagnetic ordering with a magnetocrystalline
+anisotropy favoring an out-of-plane spin orientation. Low-temperature scanning
+tunneling microscopy (STM) measurements show a slight reduction of the
+superconducting gap of NbSe$_2$ and the formation of a vortex lattice on the
+CrBr$_3$ layer in experiments under an external magnetic field. Our results
+contribute to the broader framework of exploiting proximity effects to realize
+novel phenomena in 2D heterostructures.",2009.13465v1
+2020-11-16,Topologically stable bimerons and skyrmions in vanadium dichalcogenide Janus monolayers,"We investigate the magnetic phase diagram of 1T-vanadium dichalcogenide
+monolayers in Janus configuration (VSeTe, VSSe, and VSTe) from first
+principles. The magnetic exchange, magnetocrystalline anisotropy and
+Dzyaloshinskii-Moriya interaction (DMI) are computed using density functional
+theory calculations, while the temperature- and field-dependent magnetic phase
+diagram is simulated using large-scale atomistic spin modeling in the presence
+of thermal fluctuations. The boundaries between magnetic ordered phases and
+paramagnetic phases are determined by cross-analyzing the average topological
+charge with the magnetic susceptibility and its derivatives. We find that in
+such Janus monolayers, DMI is large enough to stabilize non-trivial chiral
+textures. In VSeTe monolayer, an asymmetrical bimeron lattice state is
+stabilized for in-plane field configuration whereas skyrmion lattice is formed
+for out-of-plane field configuration. In VSSe monolayer, a skyrmion lattice is
+stabilized for out-of-plane field configuration. This study demonstrates that
+non-centrosymmetric van der Waals magnetic monolayers can support topological
+textures close to room temperature.",2011.07813v1
+2020-11-16,Microwave spectroscopy of the low-temperature skyrmion state in Cu2OSeO3,"In the cubic chiral magnet Cu2OSeO3 a low-temperature skyrmion state (LTS)
+and a concomitant tilted conical state are observed for magnetic fields
+parallel to <100>. In this work, we report on the dynamic resonances of these
+novel magnetic states. After promoting the nucleation of the LTS by means of
+field cycling, we apply broadband microwave spectroscopy in two experimental
+geometries that provide either predominantly in-plane or out-of-plane
+excitation. By comparing the results to linear spin-wave theory, we clearly
+identify resonant modes associated with the tilted conical state, the
+gyrational and breathing modes associated with the LTS, as well as the
+hybridization of the breathing mode with a dark octupole gyration mode mediated
+by the magnetocrystalline anisotropies. Most intriguingly, our findings suggest
+that under decreasing fields the hexagonal skyrmion lattice becomes unstable
+with respect to an oblique deformation, reflected in the formation of elongated
+skyrmions.",2011.07826v1
+2020-12-12,Electrically Controllable Crystal Chirality Magneto-Optical Effects in Collinear Antiferromagnets,"The spin chirality, created by magnetic atoms, has been comprehensively
+understood to generate and control the magneto-optical effects. In comparison,
+the role of the crystal chirality that relates to nonmagnetic atoms has
+received much less attention. Here, we theoretically discover the crystal
+chirality magneto-optical (CCMO) effects, which depend on the chirality of
+crystal structures that originates from the rearrangement of nonmagnetic atoms.
+We show that the CCMO effects exist in many collinear antiferromagnets, such as
+RuO$_{2}$ and CoNb$_{3}$S$_{6}$, which has a local and global crystal
+chirality, respectively. The key character of the CCMO effects is the sign
+change if the crystal chirality reverses. The magnitudes of the CCMO spectra
+can be effectively manipulated by reorienting the N\'eel vector with the help
+of an external electric field, and the spectral integrals are found to be
+proportional to magnetocrystalline anisotropy energy.",2012.06693v1
+2020-12-21,Magnetic order of Dy$^{3+}$ and Fe$^{3+}$ moments in antiferromagnetic DyFeO$_{3}$ probed by spin Hall magnetoresistance and spin Seebeck effect,"We report on spin Hall magnetoresistance (SMR) and spin Seebeck effect (SSE)
+in single crystal of the rare-earth antiferromagnet DyFeO$_{3}$ with a thin Pt
+film contact. The angular shape and symmetry of the SMR at elevated
+temperatures reflect the antiferromagnetic order of the Fe$^{3+}$ moments as
+governed by the Zeeman energy, the magnetocrystalline anisotropy and the
+Dzyaloshinskii-Moriya interaction. We interpret the observed linear dependence
+of the signal on the magnetic field strength as evidence for field-induced
+order of the Dy$^{3+}$ moments up to room temperature. At and below the Morin
+temperature of 50$\,$K, the SMR monitors the spin-reorientation phase
+transition of Fe$^{3+}$ spins. Below 23$\,$K, additional features emerge that
+persist below 4$\,$K, the ordering temperature of the Dy$^{3+}$ magnetic
+sublattice. We conclude that the combination of SMR and SSE is a simple and
+efficient tool to study spin reorientation phase transitions and sublattice
+magnetizations.",2012.11469v1
+2021-03-30,Thermal annealing enhancement of Josephson critical currents in ferromagnetic CoFeB,"The electrical and structural properties of Co40Fe40B20 (CoFeB) alloy are
+tunable with thermal annealing. This is key in the optimization of CoFeB-based
+spintronic devices, where the advantageously low magnetic coercivity, high spin
+polarization, and controllable magnetocrystalline anisotropy are utilised. So
+far, there has been no report on superconducting devices based on CoFeB. Here,
+we report Nb/CoFeB/Nb Josephson devices and demonstrate an enhancement of the
+critical current by up to 700% following thermal annealing due to increased
+structural ordering of the CoFeB. The results demonstrate that CoFeB is a
+promising material for the development of superconducting spintronic devices.",2103.16136v1
+2021-04-24,Electric-field driven stability control of skyrmions in an ultrathin transition-metal film,"To realize future spintronic applications with magnetic skyrmions --
+topologically nontrivial swirling spin structures -- it is essential to achieve
+efficient writing and deleting capabilities of these quasi-particles.
+Electric-field assisted nucleation and annihilation is a promising route,
+however, the understanding of the underlying microscopic mechanisms is still
+limited. Here, we show how the stability of individual magnetic skyrmions in an
+ultrathin transition-metal film can be controlled via external electric fields.
+We demonstrate based on density functional theory that it is important to
+consider the changes of all interactions with electric field, i.e., the
+pair-wise exchange, the Dzyaloshinskii-Moriya interaction, the
+magnetocrystalline anisotropy energy, and the higher-order exchange
+interactions. The energy barriers for electric-field assisted skyrmion writing
+and deleting obtained via atomistic spin simulations vary by up to a factor of
+three more than the variations of the interactions calculated from
+first-principles. This surprising effect originates from the electric-field
+dependent size of metastable skyrmions at a fixed magnetic field. The large
+changes of lifetimes allow the possibility of electric-field assisted thermally
+activated writing and deleting of skyrmions.",2104.11986v2
+2021-06-24,Large-scale epitaxy of two-dimensional van der Waals room-temperature ferromagnet Fe5GeTe2,"In recent years, two-dimensional van der Waals materials have emerged as an
+important platform for the observation of long-range ferromagnetic order in
+atomically thin layers. Although heterostructures of such materials can be
+conceived to harness and couple a wide range of magneto-optical and
+magneto-electrical properties, technologically relevant applications require
+Curie temperatures at or above room-temperature and the ability to grow films
+over large areas. Here we demonstrate the large-area growth of single-crystal
+ultrathin films of stoichiometric Fe5GeTe2 on an insulating substrate using
+molecular beam epitaxy. Magnetic measurements show the persistence of soft
+ferromagnetism up to room temperature, with a Curie temperature of 293 K, and a
+weak out-of-plane magnetocrystalline anisotropy. Surface, chemical, and
+structural characterizations confirm the layer-by-layer growth, 5:1:2 Fe:Ge:Te
+stoichiometric elementary composition, and single crystalline character of the
+films.",2106.12808v1
+2021-08-12,Magnetic interactions and spin excitations in van der Waals ferromagnet VI$_3$,"Using a combination of density functional theory (DFT) and spin-wave theory
+methods, we investigate the magnetic interactions and spin excitations in
+semiconducting VI$_3$. Exchange parameters of monolayer, bilayer, and bulk
+forms are evaluated by mapping the magnetic energies of various spin
+configurations, calculated using DFT+$U$, onto the Heisenberg model. The
+intralayer couplings remain largely unchanged in three forms of VI$_3$, while
+the interlayer couplings show stronger dependence on the dimensionality of the
+materials. We calculate the spin-wave spectra within a linear spin-wave theory
+and discuss how various exchange parameters affect the magnon bands. The
+magnon-magnon interaction is further incorporated, and the Curie temperature is
+estimated using a self-consistently renormalized spin-wave theory. To
+understand the roles of constituent atoms on magnetocrystalline anisotropy
+energy (MAE), we resolve MAE into sublattices and find that a strong negative
+V-I inter-sublattice contribution is responsible for the relatively small
+easy-axis MAE in VI$_3$.",2108.05528v1
+2021-09-15,Nonlinear One-Dimensional Constitutive Model for Magnetostrictive Materials,"This paper presents an analytic model of one dimensional magnetostriction. We
+show how specific assumptions regarding the symmetry of key micromagnetic
+energies (magnetocrystalline, magnetoelastic, and Zeeman) reduce a general
+three-dimensional statistical mechanics model to a one-dimensional form with an
+exact solution. We additionally provide a useful form of the analytic equations
+to help ensure numerical accuracy. Numerical results show that the model
+maintains accuracy over a large range of applied magnetic fields and stress
+conditions extending well outside those produced in standard laboratory
+conditions. A comparison to experimental data is performed for several
+magnetostrictive materials. The model is shown to accurately predict the
+behavior of Terfenol-D, while two compositions of Galfenol are modeled with
+varying accuracy. To conclude we discuss what conditions facilitate the
+description of materials with cubic crystalline anisotropy as transversely
+isotropic, to achieve peak model performance.",2109.07240v1
+2021-10-29,Two types of magnetic bubbles in MnNiGa observed via Lorentz microscopy,"Magnetic bubbles are remarkable spin structures that developed in uniaxial
+magnets with strong magnetocrystalline anisotropy. Several contradictory
+reports have been published concerning the magnetic bubble structure in a
+metallic magnet MnNiGa: Biskyrmions or type-II bubbles. Lorentz microscopy in
+polycrystalline MnNiGa was used to explain the magnetic bubble structure.
+Depending on the connection between the magnetic easy axis and the observation
+plane, two types of magnetic bubbles were formed. Magnetic bubbles with
+180{\deg} domains were formed if the easy axis was away from the direction
+perpendicular to the observation plane. The contrast of biskyrmion is
+reproduced by this form of a magnetic bubble. When the easy axis was
+approximately perpendicular to the observing plane, type-II bubbles were
+observed in the same specimen. The findings will fill a knowledge gap between
+prior reports on magnetic bubbles in MnNiGa.",2110.15507v1
+2021-11-09,Design of soft magnetic materials,"We present a strategy for the design of ferromagnetic materials with
+exceptionally low magnetic hysteresis, quantified by coercivity. In this
+strategy, we use a micromagnetic algorithm that we have developed in previous
+research and which has been validated by its success in solving the ""Permalloy
+Problem"" -- the well-known difficulty of predicting the composition 78.5% Ni of
+lowest coercivity in the Fe-Ni system -- and by the insight, it provides into
+the ""Coercivity Paradox"" of W. F. Brown. Unexpectedly, the design strategy
+predicts that cubic materials with large saturation magnetization $m_s$ and
+large magnetocrystalline anisotropy constant $\kappa_1$ will have low
+coercivity on the order of that of Permalloy, as long as the magnetostriction
+constants $\lambda_{100}, \lambda_{111}$ are tuned to special values. The
+explicit prediction for a cubic material with low coercivity is the
+dimensionless number $(c_{11}-c_{12}) \lambda_{100}^2/\kappa_1 = 81$ for
+$\langle 100 \rangle$ easy axes. The results would seem to have a broad
+potential application, especially to magnetic materials of interest in energy
+research.",2111.05456v1
+2021-11-16,Nature of Interfacial Dzyaloshinskii-Moriya Interactions in Graphene/Co/Pt(111) Multilayer Heterostructures,"DFT calculations within the generalized Bloch theorem approach show that
+interfacial Dzyaloshinskii-Moriya interactions (DMI) at both interfaces of
+Graphene/Co$_n$/Pt(111) multilayer heterostructures are decoupled for $n \geq
+3$. Unlike the property of magnetocrystalline anisotropy for this system, DMI
+is not affected by stacking defects in the Co layer. The effect of Graphene
+(Gr) is to invert the chirality of the vaccum/Co interfacial DMI, overall
+reducing the DMI of the heterostructure, which is nevertheless dominated by the
+strong spin-orbit coupling (SOC) of Pt. A spectral analysis in the reciprocal
+space shows that DMI at both the Gr/Co and Co/Pt interfaces have the same
+nature, namely SOC-split hybrid bands of $d$-orbital character. This proves
+that a DMI model based on a single band, such the Rashba DMI model, is
+insuficient to describe the behaviour of this family of Gr-capped $3d/5d$ metal
+heterostructures.",2111.08556v1
+2022-03-08,Breathing skyrmions in chiral antiferromagnets,"Breathing oscillations of skyrmions in chiral antiferromagnets can be excited
+by a temporal modification of the Dzyaloshinskii-Moriya interaction or
+magnetocrystalline anisotropy strength. We employ an adiabatic approximation
+and derive a formula for the potential that directly implies breathing
+oscillations. We study the nonlinear regime and the features of larger
+amplitude oscillations. We show that there is a maximum amplitude supported by
+the potential. As a consequence, we predict theoretically and observe
+numerically skyrmion annihilation events due to excitation of large amplitude
+breathing oscillations. The process is efficient when the skyrmion is mildly
+excited so that its radius initially grows, while the annihilation event is
+eventually induced by the internal breathing dynamics. We reveal the
+counter-intuitive property that the skyrmion possesses a nonzero kinetic energy
+at the moment of its annihilation. Finally, the frequency of small amplitude
+breathing oscillations is determined.",2203.04157v1
+2022-04-06,Sensitivity of the MnTe valence band to orientation of magnetic moments,"An effective model of the hexagonal (NiAs-structure) manganese telluride
+valence band in the vicinity of the A-point of the Brillouin zone is derived.
+It is shown that while for the usual antiferromagnetic order (magnetic moments
+in the basal plane) band splitting at A is small, their out-of-plane rotation
+enhances the splitting dramatically (to about 0.5 eV). We propose extensions of
+recent experiments (Moseley et al., Phys. Rev. Materials 6, 014404) where such
+inversion of magnetocrystalline anisotropy has been observed in Li-doped MnTe,
+to confirm this unusual sensitivity of a semiconductor band structure to
+magnetic order.",2204.04206v3
+2022-07-19,Micromagnetic simulation of neutron scattering from spherical nanoparticles: Effect of pore-type defects,"We employ micromagnetic simulations to model the effect of pore-type
+microstructural defects on the magnetic small-angle neutron scattering cross
+section and the related pair-distance distribution function of spherical
+magnetic nanoparticles. Our expression for the magnetic energy takes into
+account the isotropic exchange interaction, the magnetocrystalline anisotropy,
+the dipolar interaction, and an externally applied magnetic field. The
+signatures of the defects and the role of the dipolar energy are highlighted
+and the effect of a particle-size distribution is studied. The results serve as
+a guideline to the experimentalist.",2207.09164v1
+2022-07-23,Coexistence of Weyl semimetal and Weyl nodal loop semimetal phases in a collinear antiferromagnet,"Antiferromagnets (AFMs) with anomalous quantum responses have lead to new
+progress for the understanding of their magnetic and electronic structures from
+symmetry and topology points of view. Two typical topological states are the
+collinear antiferromagnetic Weyl semimetal (WSM) and Weyl nodal loop semimetal
+(WNLSM). In comparison with the counterparts in ferromagnets and non-collinear
+AFMs, the WSMs and WNLSMs in collinear AFMs are still waiting for experimental
+verification. In this work, we theoretically predicted the coexistence of Weyl
+points (WPs) and Weyl nodal loops (WNLs) in transition metal oxide RuO2. Owing
+to the small magnetocrystalline anisotropy energy, the WPs and WNLs can
+transform to each other via tuning the Neel vector. Moreover, since the WPs are
+very close to Fermi level and the WNLs are even crossing Fermi level, the
+topological states in RuO2 can be easily probed by photoemission and STM
+methods. Our result provides a promising material platform for the study of WSM
+and WNLSM states in collinear AFMs.",2207.11472v1
+2022-08-17,"Magnetic, electronic, and structural investigation of the strongly correlated Y$_{1-x}$Sm$_x$Co$_5$ system","SmCo$_5$ and YCo$_5$ are isostructural compounds both showing large
+magnetocrystalline anisotropy, where the former originates mainly from the
+crystal-electric field and magnetic interactions. We investigate the
+contribution of both interactions by partially substituting Y by Sm in as-cast
+polycrystalline Y$_{1-x}$Sm$_{x}$Co$_5$ (with $x$=0, 0.1, 0.2, 0.3, and 0.4)
+and measuring their structural, magnetic, and electrical properties through
+X-ray diffraction, magnetization, and electrical transport measurements. Our
+results suggest an interplay between microstructure strain in as-cast samples
+and the electronic and magnetic interactions.",2208.08545v1
+2022-08-19,Strain-Driven Zero-Field Near-10 nm Skyrmions in Two-Dimensional van der Waals Heterostructures,"Magnetic skyrmions $-$ localized chiral spin structures $-$ show great
+promise for spintronic applications. The recent discovery of two-dimensional
+(2D) magnetic materials opened new opportunities for exploring such topological
+spin structures in atomically thin van der Waals (vdW) materials. Despite
+recent progress in stabilizing metastable skyrmions in 2D magnets, their
+diameters are still beyond 100~nm and their lifetime, which is essential for
+applications, has not been explored yet. Here, using first-principles
+calculations and atomistic spin simulations, we predict that compressive
+mechanical strain leads to stabilizing zero-field skyrmions with diameters
+close to 10 nm in a Fe$_3$GeTe$_2$/germanene vdW heterostructure. The origin of
+these unique skyrmions is attributed to the high tunability of
+Dzyaloshinskii-Moriya interaction and magnetocrystalline anisotropy energy by
+strain, an effect which is shown to be general for Fe$_3$GeTe$_2$
+heterostructures with buckled substrates. Based on our first-principles
+parameters for the magnetic interactions, we calculate the energy barriers
+protecting skyrmions against annihilation and their lifetimes using
+transition-state theory. We show that nanoscale skyrmions in strained
+Fe$_3$GeTe$_2$/germanene can be stable for hours at temperatures up to 20 K.",2208.09210v1
+2022-09-01,Two-dimensional half Chern-Weyl semimetal with multiple screw axes,"Half topological states of matter and two-dimensional (2D) magnetism have
+gained much attention recently. In this paper, we propose a special topological
+semimetal phase called a 2D half Chern-Weyl semimetal (HCWS), which is a 2D
+magnetic Weyl semimetal bound to the half Chern insulator phase by symmetry,
+and the two phases can be converted to each other by manipulating the
+magnetization direction. We provide the symmetry conditions to realize this
+state in 2D systems with multiple screw axes. Tight-binding models with
+multiple basis and a predicted 2D material, monolayer TiTe, are shown as the
+concrete examples for HCWSs. The TiTe monolayer was shown to have a high
+ferremagnetic Curie temperature (~966 K) as well as a Coulomb
+correlation-enhanced spin-orbit coupling (SOC), and further demonstrates the
+effect of correlation-enhanced SOC on magnetocrystalline anisotropy energy and
+energy gap opening. Our work reveals a state with switchable and spin-resolved
+half body charge currents as well as half boundary charge currents, and will
+provide a platform for novel and high-performance topological spintronics
+devices.",2209.00330v1
+2022-10-20,Large orbital magnetic moment in VI3,"The existence of the V3+ ion orbital moment is the open issue of the nature
+of magnetism in the van der Waals ferromagnet VI3. The huge magnetocrystalline
+anisotropy in conjunction with the significantly reduced ordered magnetic
+moment compared to the spin-only value provides strong but indirect evidence of
+a significant V orbital moment. We used the unique capability of X-ray magnetic
+circular dichroism to determine the orbital component of the total magnetic
+moment and provide for the first time a direct proof of an exceptionally
+sizable orbital moment of the V3+ ion in VI3. Our ligand field multiplet
+simulations of the XMCD spectra in synergy with the results of DFT calculations
+agree with the existence of two V sites with different orbital occupations and
+therefore different OM magnitudes in the ground state.",2210.11278v1
+2022-10-25,Tuning of topological properties in the strongly correlated antiferromagnet Mn$_3$Sn via Fe doping,"Magnetic topological materials, in which strong correlations between magnetic
+and electronic properties of matter, give rise to various exotic phenomena such
+as anomalous Hall effect (AHE), topological Hall effect (THE), and skyrmion
+lattice. Here, we report on the electronic, magnetic, and topological
+properties of Mn$_{3-\it{x}}$Fe$_{\it{x}}$Sn single crystals ($\it{x}$=0, 0.25,
+and 0.35). Low temperature magnetic properties have been significantly changed
+with Fe doping. Most importantly, we observe that large uniaxial
+magnetocrystalline anisotropy that is induced by the Fe doping in combination
+with competing magnetic interactions at low temperature produce nontrivial
+spin-texture, leading to large topological Hall effect in the doped systems at
+low temperatures. Our studies further show that the topological properties of
+Mn$_{3-\it{x}}$Fe$_{\it{x}}$Sn are very sensitive to the Fe doping.",2210.14150v1
+2022-11-21,Inertial dynamics and equilibrium correlation functions of magnetization at short times,"The method of moments is developed and employed to analyze the equilibrium
+correlation functions of the magnetization of ferromagnetic nanoparticles in
+the case of inertial magnetization dynamics. The method is based on the Taylor
+series expansion of the correlation functions and the estimation of the
+expansion coefficients. This method significantly reduces the complexity of
+analysis of equilibrium correlation functions. Analytical expressions are
+derived for the first three coefficients for the longitudinal and transverse
+correlation functions for the uniaxial magnetocrystalline anisotropy of
+ferromagnetic nanoparticles with a longitudinal magnetic field. The limiting
+cases of very strong and negligibly weak external longitudinal fields are
+considered. The Gordon sum rule for inertial magnetization dynamics is
+discussed. In addition, we show that finite analytic series can be used as a
+simple and satisfactory approximation for the numerical calculation of
+correlation functions at short times.",2211.11515v2
+2023-01-24,Ru$_{2-x}$Mn$_{1+x}$Al thin films,"The cubic Heusler alloy Ru$_{2-x}$Mn$_{1+x}$Al is grown in thin film form on
+MgO and MgAl$_2$O$_4$ substrates. It is a highly spin-polarised ferrimagnetic
+metal, with weak magnetocrystalline anisotropy. Although structurally and
+chemically similar to $\text{Mn}_2\text{Ru}_x\text{Ga}$, it does not exhibit
+ferrimagnetic compensation, or large magneto galvanic effects. The differences
+are attributed to a combination of atomic order and the hybridisation with the
+group 13 element Al or Ga. The spin polarisation is around 50 to 60 %. There is
+a gap in the density of states just above the Fermi level in fully ordered
+compounds.",2301.10148v2
+2023-02-04,"Room Temperature Ferroelectricity, Ferromagnetism, and Anomalous Hall Effect in Half-metallic Monolayer CrTe","Two-dimensional materials hosting ferroelectricity and ferromagnetism are
+crucial for low-power and high-speed information processing technologies.
+However, intrinsic 2D multiferroics in the monolayer limit are rare. Here, we
+demonstrate that monolayer CrTe, obtained by cleaving the [002] surface, is
+dynamically stable multiferroic at temperatures beyond room temperature. We
+show that it orders ferromagnetically with significant in-plane
+magnetocrystalline anisotropy, and it is a half-metal featuring a large
+half-metal gap. Remarkably, the broken inversion symmetry and buckled geometry
+of monolayer CrTe make it a ferroelectric with a large spontaneous out-of-plane
+polarization and significant magnetoelectric coupling. In addition, we
+demonstrate polarization or electric field-induced tunability of the anomalous
+Hall effect, accompanied by substantial bandstructure modulation. Our findings
+establish monolayer CrTe as a room-temperature multiferroic with great
+potential for applications in spintronics and ferroelectric devices.",2302.02145v2
+2023-03-01,Tailed skyrmions -- an obscure branch of magnetic solitons,"We report tailed skyrmions -- a new class of stable soliton solutions of the
+2D chiral magnet model. Tailed skyrmions have elongated shapes and emerge in a
+narrow range of fields near the transition between the spin spirals and the
+saturated state. We analyze the stability range of these solutions in terms of
+external magnetic field and magnetocrystalline anisotropy. Minimum energy paths
+and the homotopies (continuous transitions) between tailed skyrmions of the
+same topological charge have been calculated using the geodesic nudged elastic
+bands method. The discovery of tailed skyrmions extends the diversity of
+already-known solutions illustrated by complex morphology solitons, such as
+tailed skyrmion bags with and without chiral kinks.",2303.00347v1
+2023-03-03,Magneto-optical sensing of the pressure driven magnetic ground states in bulk CrSBr,"Competition between exchange interactions and magnetocrystalline anisotropy
+may bring new magnetic states that are of great current interest. An applied
+hydrostatic pressure can further be used to tune their balance. In this work we
+investigate the magnetization process of a biaxial antiferromagnet in an
+external magnetic field applied along the easy axis. We find that the single
+metamagnetic transition of the Ising type observed in this material under
+ambient pressure transforms under hydrostatic pressure into two transitions, a
+first-order spin flop transition followed by a second order transition towards
+a polarized ferromagnetic state near saturation. This reversible tuning into a
+new magnetic phase is obtained in layered bulk CrSBr at low temperature by
+varying the interlayer distance using high hydrostatic pressure, which
+efficiently acts on the interlayer magnetic exchange, and is probed by
+magneto-optical spectroscopy.",2303.01823v2
+2023-04-24,Fast non-volatile electric control of antiferromagnetic states,"Electrical manipulation of antiferromagnetic states, a cornerstone of
+antiferromagnetic spintronics, is a great challenge, requiring novel material
+platforms. Here we report the full control over antiferromagnetic states by
+voltage pulses in the insulating Co$_3$O$_4$ spinel. We show that the strong
+linear magnetoelectric effect emerging in its antiferromagnetic state is fully
+governed by the orientation of the N\'eel vector. As a unique feature of
+Co$_3$O$_4$, the magnetoelectric energy can easily overcome the weak
+magnetocrystalline anisotropy, thus, the N\'eel vector can be manipulated on
+demand, either rotated smoothly or reversed suddenly, by combined electric and
+magnetic fields. We succeed with switching between antiferromagnetic states of
+opposite N\'eel vectors by voltage pulses within a few microsecond in
+macroscopic volumes. These observations render quasi-cubic antiferromagnets,
+like Co$_3$O$_4$, an ideal platform for the ultrafast (pico- to nanosecond)
+manipulation of microscopic antiferromagnetic domains and may pave the way for
+the realization of antiferromagnetic spintronic devices.",2304.12270v1
+2023-07-05,Multi-level recording in dual-layer FePt-C granular film for heat-assisted magnetic recording,"Multi-level magnetic recording is a new concept for increasing the data
+storage capacity of hard disk drives. However, its implementation has been
+limited by a lack of suitable media capable of storing information at multiple
+levels. Herein, we overcome this problem by developing dual FePt-C nanogranular
+films separated by a Ru-C breaking layer with a cubic crystal structure. The
+FePt grains in the bottom and top layers of the developed media exhibited
+different effective magnetocrystalline anisotropies and Curie temperatures. The
+former is realized by different degrees of ordering in the L10-FePt grains,
+whereas the latter was attributed to the diffusion of Ru, thereby enabling
+separate magnetic recordings at each layer under different magnetic fields and
+temperatures. Furthermore, the magnetic measurements and heat-assisted magnetic
+recording simulations showed that these media enabled 3-level recording and
+could potentially be extended to 4-level recording, as the up-down and down-up
+states exhibited non-zero magnetization.",2307.02213v1
+2023-08-22,Effect of Electron-Phonon Scattering on the Anomalous Hall Conductivity of Fe$_3$Sn: A Kagome Ferromagnetic Metal,"We report on magnetic and magnetotransport studies of a Kagome ferromagnetic
+metal, Fe$_3$Sn. Our studies reveal a large anomalous Hall conductivity
+($\sigma_{zx}$) in this system, mainly contributed by temperature independent
+intrinsic Hall conductivity ($\sigma^{int}_{zx}$=485$\pm$60 S/cm) and
+temperature dependent extrinsic Hall conductivity ($\sigma^{ext}_{zx}$) due to
+skew-scattering. Although $\sigma^{ext}_{zx}$ value is large and almost
+equivalent to the intrinsic Hall conductivity at low temperatures, it
+drastically decreases with increasing temperature, following the relation
+$\sigma^{ext}_{zx}=\frac{\sigma_{zx0}^{ext}}{(aT+1)^2}$, under the influence of
+electron-phonon scattering. The presence of electron-phonon scattering in this
+system is also confirmed by the linear dependence of longitudinal electrical
+resistivity at higher temperatures [$\rho(T)\propto T$]. We further find that
+Fe$_3$Sn is a soft ferromagnet with an easy-axis of magnetization lying in the
+$\it{ab}$ plane of the crystal with magnetocrystalline anisotropy energy
+density as large as 1.02 $\times$ 10$^6$",2308.11177v1
+2023-08-22,"Tuning of Electrical, Magnetic, and Topological Properties of Magnetic Weyl Semimetal Mn$_{3+x}$Ge by Fe doping","We report on the tuning of electrical, magnetic, and topological properties
+of the magnetic Weyl semimetal (Mn$_{3+x}$Ge) by Fe doping at the Mn site,
+Mn$_{(3+x)-\delta}$Fe$_{\delta}$Ge ($\delta$=0, 0.30, and 0.62). Fe doping
+significantly changes the electrical and magnetic properties of Mn$_{3+x}$Ge.
+The resistivity of the parent compound displays metallic behavior, the system
+with $\delta$=0.30 of Fe doping exhibits semiconducting or bad-metallic
+behavior, and the system with $\delta$=0.62 of Fe doping demonstrates a
+metal-insulator transition at around 100 K. Further, we observe that the Fe
+doping increases in-plane ferromagnetism, magnetocrystalline anisotropy, and
+induces a spin-glass state at low temperatures. Surprisingly, topological Hall
+state has been noticed at a Fe doping of $\delta$=0.30 that is not found in the
+parent compound or with $\delta$=0.62 of Fe doping. In addition, spontaneous
+anomalous Hall effect observed in the parent system is significantly reduced
+with increasing Fe doping concentration.",2308.11183v1
+2023-09-12,Probing spatial variation of magnetic order in strained SrMnO$_3$ thin films using Spin Hall Magnetoresistance,"SrMnO$_{3}$ (SMO) is a magnetic insulator and predicted to exhibit a
+multiferroic phase upon straining. Strained films of SMO display a wide range
+of magnetic orders, ranging from G-type to C-and A-type, indicative of
+competing magnetic interactions. The potential of spin Hall magnetoresistance
+(SMR) is exploited as an electrical probe for detecting surface magnetic order,
+to read surface magnetic moments in SMO and its spatial variation, by designing
+and positioning electrodes of different sizes on the film. The findings
+demonstrate antiferromagnetic domains with different magnetocrystalline
+anisotropies along with a ferromagnetic order, where the magnetization arises
+from double exchange mediated ferromagnetic order and canted antiferromagnetic
+moments. Further, from a complete analysis of the SMR, a predominance of
+antiferromagnetic domain sizes of 3.5 $\mu$m$^2$ is extracted. This work
+enhances the applicability of SMR in unraveling the richness of correlation
+effects in complex oxides, as manifested by the detection of coexisting and
+competing ground states and lays the foundation for the study of magnon
+transport for different magnetoelectric based computing applications.",2309.06279v1
+2023-09-16,Colossal linear magnetoelectricity in polar magnet Fe2Mo3O8,"Linear magnetoelectric effect is an attractive phenomenon in condensed
+matters and provides indispensable technological functionalities. Here a
+colossal linear magnetoelectric effect with diagonal component alfa_33 reaching
+up to ~480 ps/m is reported in a polar magnet Fe2Mo3O8, and this effect can
+persist in a broad range of magnetic field (~20 T) and is orders of magnitude
+larger than reported values in literature. Such an exceptional experimental
+observation can be well reproduced by a theoretical model affirmatively
+unveiling the vital contributions from the exchange striction, while the sign
+difference of magnetocrystalline anisotropy can also be reasonably figured out.",2309.08974v1
+2023-11-07,"Magnetism in AV3Sb5 (A = Cs, Rb, K): Complex Landscape of the Dynamical Magnetic Textures","We have investigated the dynamical magnetic properties of the V-based kagome
+stibnite compounds by combining the ab-initio calculated magnetic parameters of
+a spin Hamiltonian like inter-site exchange parameters, magnetocrystalline
+anisotropy and site projected magnetic moments, with full-fledged simulations
+of atomistic spin-dynamics. Our calculations reveal that in addition to a
+ferromagnetic order along the [001] direction, the system hosts a complex
+landscape of magnetic configurations comprised of commensurate and
+incommensurate spin-spirals along the [010] direction. The presence of such
+chiral magnetic textures may be the key to solve the mystery about the origin
+of the experimentally observed inherent breaking of the C6 rotational symmetry-
+and the time-reversal symmetry.",2311.04099v1
+2023-11-30,Growth of high-quality CrI3 single crystals and engineering of its magnetic properties via V and Mn doping,"CrI3, as a soft van der Waals layered magnetic material, has been widely
+concerned and explored for its magnetic complexity and tunability. In this
+work, high quality and large size thin CrI3, V and Mn doped single crystals
+were prepared by chemical vapor transfer method. A remarkable irreversible
+Barkhausen effect was observed in CrI3 and CrMn0.06I3, which can be attributed
+to the low dislocation density that facilitates movement of the domain walls.
+In addition, the introduction of the doping element Mn allows higher saturation
+magnetization intensity. Cr0.5V0.5I3 exhibits substantially increased
+coercivity force and larger magnetocrystalline anisotropy compared to CrI3,
+while kept similar Curie temperature and good environmental stability. The
+first principles calculations suggest direct and narrowed band gaps in
+Cr0.5V0.5I3 and VI3 comparing to CrI3. The smaller band gaps and good hard
+magnetic property make Cr0.5V0.5I3 an alternative choice to future research of
+spintronic devices.",2311.18360v1
+2024-01-29,"Magnetic, thermodynamic, and magnetotransport properties of CeGaGe and PrGaGe single crystals","We investigate the physical properties of high-quality single crystals CeGaGe
+and PrGaGe using magnetization, heat capacity, and magnetotransport
+measurements. Gallium-indium binary flux was used to grow these single crystals
+that crystallize in a body-centered tetragonal structure. Magnetic
+susceptibility data reveal a magnetic phase transition around 6.0 and 19.4 K in
+CeGaGe and PrGaGe, respectively, which is further confirmed by heat capacity
+and electrical resistivity data. A number of additional anomalies have been
+observed below the ordering temperature in the magnetic susceptibility data,
+indicating a complex magnetic structure. The magnetic measurements also reveal
+a strong magnetocrystalline anisotropy in both compounds. Our detailed analysis
+of the crystalline electric field (CEF) effect as observed in magnetic
+susceptibility and heat capacity data suggests that the $J$ = 5/2 multiplet of
+CeGaGe splits into three doublets, while the $J$ = 4 degenerate ground state of
+PrGaGe splits into five singlets and two doublets. The estimated energy levels
+from the CEF analysis are consistent with the magnetic entropy.",2401.15907v1
+2024-01-31,Prediction of stable nanoscale skyrmions in monolayer Fe$_5$GeTe$_2$,"Using first-principles calculations and atomistic spin simulations, we
+predict stable isolated skyrmions with a diameter below 10 nm in a monolayer of
+the two-dimensional van der Waals ferromagnet Fe$_5$GeTe$_2$, a material of
+significant experimental interest. A very large Dzyaloshinskii-Moriya
+interaction (DMI) is observed due to the intrinsic broken inversion symmetry
+and strong spin-orbit coupling for monolayer Fe$_5$GeTe$_2$. We show that the
+nearest-neighbor approximation, often used in literature, fails to describe the
+DMI. The strong DMI together with moderate in-plane magnetocrystalline
+anisotropy energy allows to stabilize nanoscale skyrmions in out-of-plane
+magnetic fields above $\approx 2$~T. The energy barriers of skyrmions in
+monolayer Fe$_5$GeTe$_2$ are comparable to those of state-of-the-art
+transition-metal ultra-thin films. We further predict that these nanoscale
+skyrmions can be stable for hours at temperatures up to 20 K.",2401.18000v1
+2024-02-09,Configuration of the magnetosome chain: a natural magnetic nanoarchitecture,"Magnetospirillum gryphiswaldense is a microorganism with the ability to
+biomineralize magnetite nanoparticles, called magnetosomes, and arrange them
+into a chain that behaves like a magnetic compass. Rather than straight lines,
+magnetosome chains are slightly bent, as evidenced by electron cryotomography.
+Our experimental and theoretical results suggest that due to the competition
+between the magnetocrystalline and shape anisotropies, the effective magnetic
+moment of individual magnetosomes is tilted out of the [111] crystallographic
+easy axis of magnetite. This tilt does not affect the direction of the chain
+net magnetic moment, which remains along the [111] axis, but explains the
+arrangement of magnetosomes in helical-like shaped chains. Indeed, we
+demonstrate that the chain shape can be reproduced by considering an interplay
+between the magnetic dipolar interactions between magnetosomes, ruled by the
+orientation of the magnetosome magnetic moment, and a lipid/protein-based
+mechanism, modeled as an elastic recovery force exerted on the magnetosomes.",2402.06375v1
+2024-02-29,Searching for magnetically hard monoborides (and finding a few): A first-principles investigation,"New hard magnetic materials with zero or low rare earth content are in demand
+due to the high prices of the rare earth metals. Among the candidates for such
+materials, we consider MnB, FeB and their alloys, because previous experiments
+suggest that FeB has a relatively high magnetic hardness of about 0.83 at room
+temperature. Using first-principles calculations, we examine the full range of
+alloys from CrB, through MnB, FeB, to CoB. Furthrmore, we consider alloys of
+MnB and FeB with substitutions of 3$d$, 4$d$ and 5$d$ transition metals. For
+the above ninety compositions, we determine magnetic moment, magnetocrystalline
+anisotropy energy and magnetic hardness. For (Fe-Co)B alloys, the calculated
+values of magnetic hardness exceed five, which is an exceptionally high. While
+these values are inflated by the virtual crystal approximation used, we still
+expect actual magnetic hardnesses well above unity. Furthermore, we classify
+considered MnB alloys substituted with transition metals as magnetically soft
+or semi-hard and FeB alloys with Sc, Ti, V, Zr, Nb, Mo, Hf, Ta or W as
+magnetically hard (with magnetic hardness exceeding unity).",2403.00138v1
+2006-03-06,Magnetism of iron: from the bulk to the monoatomic wire,"The magnetic properties of iron (spin and orbital magnetic moments,
+magnetocrystalline anisotropy energy) in various geometries and
+dimensionalities are investigated by using a parametrized tight-binding model
+in an $s$, $p$ and $d$ atomic orbital basis set including spin polarization and
+the effect of spin-orbit coupling. The validity of this model is well
+established by comparing the results with those obtained by using an ab-initio
+code. This model is applied to the study of iron in bulk bcc and fcc phases,
+$(110)$ and $(001)$ surfaces and to the monatomic wire, at several interatomic
+distances. New results are derived. The variation of the component of the
+orbital magnetic moment on the spin quantization axis has been studied as a
+function of depth, revealing a significant enhancement in the first two layers,
+especially for the $(001)$ surface. It is found that the magnetic anisotropy
+energy is drastically increased in the wire and can reach several meV. This is
+also true for the orbital moment, which in addition is highly anisotropic.
+Furthermore it is shown that when the spin quantization axis is neither
+parallel nor perpendicular to the wire the average orbital moment is not
+aligned with the spin quantization axis. At equilibrium distance the easy
+magnetization axis is along the wire but switches to the perpendicular
+direction under compression. The success of this model opens up the possibility
+of obtaining accurate results on other elements and systems with much more
+complex geometries.",0603121v1
+2009-03-13,Connection Between Magnetism and Structure in Fe Double Chains on the Ir(100) Surface,"The magnetic ground state of nanosized systems such as Fe double chains,
+recently shown to form in the early stages of Fe deposition on Ir(100), is
+generally nontrivial. Using ab initio density functional theory we find that
+the straight ferromagnetic (FM) state typical of bulk Fe as well as of isolated
+Fe chains and double chains is disfavored after deposition on Ir(100) for all
+the experimentally relevant double chain structures considered. So long as
+spin-orbit coupling (SOC) is neglected, the double chain lowest energy state is
+generally antiferromagnetic (AFM), a state which appears to prevail over the FM
+state due to Fe-Ir hybridization. Successive inclusion of SOC adds two further
+elements, namely a magnetocrystalline anisotropy, and a Dzyaloshinskii-Moriya
+(DM) spin-spin interaction, the former stabilizing the collinear AFM state, the
+second favoring a long-period spin modulation. We find that anisotropy is most
+important when the double chain is adsorbed on the partially deconstructed
+Ir(100) -- a state which we find to be substantially lower in energy than any
+reconstructed structure -- so that in this case the Fe double chain should
+remain collinear AFM. Alternatively, when the same Fe double chain is adsorbed
+in a metastable state onto the (5x1) fully reconstructed Ir(100) surface, the
+FM-AFM energy difference is very much reduced and the DM interaction is
+expected to prevail, probably yielding a helical spin structure.",0903.2348v1
+2013-06-16,Exchange coupling and magnetic anisotropy at Fe/FePt interfaces,"We perform fully relativistic first principles calculations of the exchange
+interactions and the magnetocrystalline anisotropy energy (MAE) in an
+Fe/FePt/Fe sandwich system in order to elucidate how the presence of Fe/FePt
+(soft/hard magnetic) interfaces impacts on the magnetic properties of
+Fe/FePt/Fe multilayers. Throughout our study we make comparisons between a
+geometrically unrelaxed system and a geometrically relaxed system. We observe
+that the Fe layer at the Fe/FePt interface plays a crucial role inasmuch its
+(isotropic) exchange coupling to the soft (Fe) phase of the system is
+substantially reduced. Moreover, this interfacial Fe layer has a substantial
+impact on the MAE of the system. We show that the MAE of the FePt slab,
+including the contribution from the Fe/FePt interface, is dominated by
+anisotropic inter-site exchange interactions. Our calculations indicate that
+the change in the MAE of the FePt slab with respect to the corresponding bulk
+value is negative, i.e., the presence of Fe/FePt interfaces appears to reduce
+the perpendicular MAE of the Fe/FePt/Fe system. However, for the relaxed
+system, this reduction is marginal. It is also shown that the relaxed system
+exhibits a reduced interfacial exchange. Using a simple linear chain model we
+demonstrate that the reduced exchange leads to a discontinuity in the
+magnetisation structure at the interface.",1306.3642v1
+2014-11-10,Symmetry-lowering lattice distortion at the spin-reorientation in MnBi single crystals,"Structural and physical properties determined by measurements on large single
+crystals of the anisotropic ferromagnet MnBi are reported. The findings support
+the importance of magneto-elastic effects in this material. X-ray diffraction
+reveals a structural phase transition at the spin reorientation temperature
+$T_{SR}$ = 90 K. The distortion is driven by magneto-elastic coupling, and upon
+cooling transforms the structure from hexagonal to orthorhombic. Heat capacity
+measurements show a thermal anomaly at the crystallographic transition, which
+is suppressed rapidly by applied magnetic fields. Effects on the transport and
+anisotropic magnetic properties of the single crystals are also presented.
+Increasing anisotropy of the atomic displacement parameters for Bi with
+increasing temperature above $T_{SR}$ is revealed by neutron diffraction
+measurements. It is likely that this is directly related to the anisotropic
+thermal expansion in MnBi, which plays a key role in the spin reorientation and
+magnetocrystalline anisotropy. The identification of the true ground state
+crystal structure reported here may be important for future experimental and
+theoretical studies of this permanent magnet material, which have to date been
+performed and interpreted using only the high temperature structure.",1411.2448v1
+2015-04-14,Magnetization induced local electric dipoles and multiferroic properties of Ba2CoGe2O7,"Ba2CoGe2O7, crystallizing in the noncentrosymmetric but nonpolar structure,
+belongs to a special class of multiferroic materials, whose properties are
+predetermined by the rotoinversion symmetry. Unlike inversion, the
+rotoinversion symmetry can be easily destroyed by the magnetization. Moreover,
+due to specific structural pattern, the magnetic structure of Ba2CoGe2O7 is
+relatively soft. Altogether, this leads to the rich variety of multiferroic
+properties, where the magnetic structure can be easily deformed by the magnetic
+field, inducing the electric polarization in the direction, which depends on
+the direction of the magnetic field. In this paper, we show that all these
+properties can be successfully explained on the basis of realistic low-energy
+model, derived from the first-principles electronic structure calculations for
+the magnetically active Co 3d bands, and the Berry-phase theory of electric
+polarization. Particularly, we argue that the magnetization induced electric
+polarization in Ba2CoGe2O7 is essentially local and expressed via the
+expectation values of some dipole matrices, calculated in the Wannier basis of
+the model, and the site-diagonal density matrices of the magnetic Co sites.
+Thus, the basic aspects of the behavior of Ba2CoGe2O7 can be understood already
+in the atomic limit, where both magnetic anisotropy and magnetoelectric
+coupling are specified by density matrix. Then, the macroscopic polarization
+can be found as a superposition of electric dipoles of the individual Co sites.
+We discuss the behavior of interatomic magnetic interactions, main
+contributions to the magnetocrystalline anisotropy and the spin canting, as
+well as the similarities and differences of the proposed picture from the
+phenomenological model of spin-dependent p-d hybridization.",1504.03540v1
+2017-04-24,Geometrical dependence of domain wall propagation and nucleation fields in magnetic domain wall sensor devices,"We study the key domain wall properties in segmented nanowires loop-based
+structures used in domain wall based sensors. The two reasons for device
+failure, namely the distribution of domain wall propagation field (depinning)
+and the nucleation field are determined with Magneto-Optical Kerr Effect (MOKE)
+and Giant Magnetoresistance (GMR) measurements for thousands of elements to
+obtain significant statistics. Single layers of Ni$_{81}$Fe$_{19}$, a complete
+GMR stack with Co$_{90}$Fe$_{10}$/Ni$_{81}$Fe$_{19}$ as a free layer and a
+single layer of Co$_{90}$Fe$_{10}$ are deposited and industrially patterned to
+determine the influence of the shape anisotropy, the magnetocrystalline
+anisotropy and the fabrication processes. We show that the propagation field is
+little influenced by the geometry but significantly by material parameters. The
+domain wall nucleation fields can be described by a typical Stoner-Wohlfarth
+model related to the measured geometrical parameters of the wires and fitted by
+considering the process parameters. The GMR effect is subsequently measured in
+a substantial number of devices (3000), in order to accurately gauge the
+variation between devices. This reveals a corrected upper limit to the
+nucleation fields of the sensors that can be exploited for fast
+characterization of working elements.",1704.07371v2
+2017-07-13,Role of Square Planar Coordination in the Magnetic Properties of Na4IrO4,"Iridates supply fertile grounds for unconventional phenomena and exotic
+electronic phases. With respect to well-studied octahedrally-coordinated
+iridates, we pay our attention to a rather unexplored iridate, Na4IrO4, showing
+an unusual square-planar coordination. The latter is key to rationalize the
+electronic structure and magnetic property of Na4IrO4, which is here explored
+by first-principles density functional theory and Monte Carlo simulations. Due
+to the uncommon square-planar crystal field, Ir 5d states adopt
+intermediate-spin state with double occupation of dz2 orbital, leading to a
+sizable local spin moment, at variance with many other iridates. The
+square-planar crystal field splitting is also crucial in opening a robust
+insulating gap in Na4IrO4, irrespective of the specific magnetic ordering or
+treatment of electronic correlations. Spin-orbit coupling plays a minor role in
+shaping the electronic structure, but leads to a strong magnetocrystalline
+anisotropy. The easy axis perpendicular to the IrO4 plaquette, well explained
+using perturbation theory, is again closely related to the square-planar
+coordination. Finally, the large single-ion anisotropy suppresses the spin
+frustration and stabilizes a collinear antiferromagnetic long-range magnetic
+ordering, as confirmed by Monte Carlo simulations predicting a quite low N\'eel
+temperature, expected from almost isolated IrO4 square-planar units as
+crystalline building blocks.",1707.04052v1
+2018-06-04,Site-Specific Spin Reorientation in Antiferromagnetic State of Quantum System SeCuO$_3$,"We report on the magnetocrystalline anisotropy energy (MAE) and spin
+reorientation in antiferromagnetic state of spin $S=1/2$ tetramer system
+SeCuO$_3$ observed in torque magnetometry measurements in magnetic fields
+$H<5$~T and simulated using density functional calculations. We employ simple
+phenomenological model of spin reorientation in finite magnetic field to
+describe our experimental torque data. Our results strongly support collinear
+model for magnetic structure in zero field with possibility of only very weak
+canting. Torque measurements also indicate that, contrary to what is expected
+for uniaxial antiferromagnet, in SeCuO$_3$ only part of the spins exhibit spin
+flop instead all of them, allowing us to conclude that AFM state of SeCuO$_3$
+is unconventional and comprised of two decoupled subsystems. Taking into
+account previously proposed site-selective correlations and dimer singlet state
+formation in this system, our results offer further proof that AFM state in
+SeCuO$_3$ is composed of a subsystem of AFM dimers forming singlets immersed in
+antiferromagnetically long-range ordered spins, where both states coexist on
+atomic scale. Furthermore, we show, using an ab-initio approach, that both
+subsystems contribute differently to the MAE, corroborating the existence of
+decoupled subnetworks in SeCuO$_3$. Combination of torque magnetometry,
+phenomenological approach and DFT simulations to magnetic anisotropy presented
+here represents a unique and original way to study site-specific reorientation
+phenomena in quantum magnets.",1806.01233v2
+2018-11-09,Correlation between site preference and magnetic properties of Zn-Sn-substituted strontium hexaferrite,"The site preference and magnetic properties of Zn, Sn and Zn-Sn substituted
+M-type strontium hexaferrite (SrFe$_{12}$O$_{19}$) have been investigated using
+first-principles total energy calculations based on density functional theory.
+The site occupancy of substituted atoms were estimated by calculating the
+substitution energies of different configurations. The distribution of
+different configurations during the annealing process at high temperature was
+determined using the formation probabilities of configurations to calculate
+magnetic properties of substituted strontium hexaferrite. We found that the
+magnetization and magnetocrystalline anisotropy are closely related to the
+distributions of Zn-Sn ions on the five Fe sites. Our calculation show that in
+SrFe$_{11.5}$Zn$_{0.5}$O$_{19}$, Zn atoms prefer to occupy $4f_1$, $12k$, and
+$2a$ sites with occupation probability of 78%, 19% and 3%, respectively, while
+in SrFe$_{11.5}$SnO$_{19}$, Sn atoms occupy the $12k$ and $4f_2$ sites with
+occupation probability of 54% and 46%, respectively. We also found that in
+SrFe$_{11}$Zn$_{0.5}$Sn$_{0.5}$O$_{19}$, (Zn,Sn) atom pairs prefer to occupy
+the ($4f_1$, $4f_2$), ($4f_1$, $12k$) and ($12k$, $12k$) sites with occupation
+probability of 82%, 8% and 6%, respectively. Our calculation shows that the
+increase of magnetization and the reduction of magnetic anisotropy in Zn-Sn
+substituted M-type strontium hexaferrite as observed experimentally is due to
+the occupation of (Zn,Sn) pairs at the ($4f_1$, $4f_2$) sites.",1811.04101v2
+2018-11-14,Unusual rotating magnetocaloric effect in the hexagonal ErMnO3 single crystal,"It is known that orthorhombic RMnO3 multiferroics (R = magnetic rare earth)
+with low symmetry exhibit a large rotating magnetocaloric effect because of
+their strong magnetocrystalline anisotropy. In this paper, we demonstrate that
+the hexagonal ErMnO3 single crystals also unveils a giant rotating
+magnetocaloric effect that can be obtained by spinning them in constant
+magnetic fields around their a or b axes. When the ErMnO3 crystal is rotated
+with the magnetic field initially parallel to the c-axis, the resulting entropy
+change reaches maximum values of 7, 17 and 20 J/kg K under a constant magnetic
+field of 2, 5 and 7 T, respectively. These values are comparable or even larger
+than those shown by some of the best orthorhombic phases. More interestingly,
+the generated anisotropic thermal effect is about three times larger than that
+exhibited by the hexagonal HoMnO3 single crystal. The enhancement of the
+rotating magnetocaloric effect in the hexagonal ErMnO3 compound arises from the
+unique features of Er3+ magnetic sublattice. In fact, the Er3+ magnetic moments
+located at 2a sites experience a first-order metamagnetic transition close to 3
+K along the c-axis resulting in a peaked magnetocaloric effect over a narrower
+temperature range. In contrast, the (paramagnetic) behaviour of Er3+ magnetic
+moments within the ab-plane, produces a larger magnetocaloric effect over a
+wider temperature range. Therefore, the magnetocaloric effect anisotropy is
+maximized between the c and the ab-directions, leading to a giant rotating
+magnetocaloric effect.",1811.05847v1
+2019-07-04,Micromagnetic modelling of magnetic domain walls and domains in cylindrical nanowires,"Magnetic cylindrical nanowires are very fascinating objects where the curved
+geometry allows many novel magnetic effects and a variety of non-trivial
+magnetic structures. Micromagnetic modelling plays an important role in
+revealing the magnetization distribution in magnetic nanowires, often not
+accessible by imaging methods with sufficient details. Here we review the
+magnetic properties of the shape anisotropy-dominated nanowires and the
+nanowires with competing shape and magnetocrystalline anisotropies, as revealed
+by micromagnetic modelling. We discuss the variety of magnetic walls and
+magnetic domains reported by micromagnetic simulations in cylindrical
+nanowires. The most known domain walls types are the transverse and vortex
+(Bloch point) domain walls and the transition between them is materials and
+nanowire diameter dependent. Importantly, the field or current-driven domain
+walls in cylindrical nanowires can achieve very high velocities. In recent
+simulations of nanowires with larger diameter the skyrmion tubes are also
+reported. In nanowires with large saturation magnetization the core of these
+tubes may form a helicoidal ('corkscrew') structure. The topology of the
+skyrmion tubes play an important role in the pinning mechanism, discussed here
+on the example of FeCo modulated nanowires. Other discussed examples include
+the influence of antinotches ('bamboo' nanowires) on the remanent magnetization
+configurations for hcp Co and FeCo nanowires and Co-Ni multisegmented
+nanowires.",1907.02318v1
+2019-11-27,Spin flop and crystalline anisotropic magnetoresistance in CuMnAs,"Recent research works have shown that the magnetic order in some
+antiferromagnetic materials can be manipulated and detected electrically, due
+to two physical mechanisms: Neel-order spin-orbit torques and anisotropic
+magnetoresistance. While these observations open up opportunities to use
+antiferromagnets for magnetic memory devices, different physical
+characterization methods are required for a better understanding of those
+mechanisms. Here we report a magnetic field induced rotation of the
+antiferromagnetic Neel vector in epitaxial tetragonal CuMnAs thin films. Using
+soft x-ray magnetic linear dichroism spectroscopy, x-ray photoemission electron
+microscopy, integral magnetometry and magneto-transport methods, we demonstrate
+spin-flop switching and continuous spin reorientation in antiferromagnetic
+films with uniaxial and biaxial magnetic anisotropies, respectively. From
+field-dependent measurements of the magnetization and magnetoresistance, we
+obtain key material parameters including the anisotropic magnetoresistance
+coefficients, magnetocrystalline anisotropy, spin-flop and exchange fields.",1911.12381v2
+2020-08-12,Metastable skyrmion lattices governed by magnetic disorder and anisotropy in $β$-Mn-type chiral magnets,"Magnetic skyrmions are vortex-like topological spin textures often observed
+in structurally chiral magnets with Dzyaloshinskii-Moriya interaction. Among
+them, Co-Zn-Mn alloys with a $\beta$-Mn-type chiral structure host skyrmions
+above room temperature. In this system, it has recently been found that
+skyrmions persist over a wide temperature and magnetic field region as a
+long-lived metastable state, and that the skyrmion lattice transforms from a
+triangular lattice to a square one. To obtain perspective on chiral magnetism
+in Co-Zn-Mn alloys and clarify how various properties related to the skyrmion
+vary with the composition, we performed systematic studies on
+Co$_{10}$Zn$_{10}$, Co$_9$Zn$_9$Mn$_2$, Co$_8$Zn$_8$Mn$_4$ and
+Co$_7$Zn$_7$Mn$_6$ in terms of magnetic susceptibility and small-angle neutron
+scattering measurements. The robust metastable skyrmions with extremely long
+lifetime are commonly observed in all the compounds. On the other hand,
+preferred orientation of a helimagnetic propagation vector and its temperature
+dependence dramatically change upon varying the Mn concentration. The
+robustness of the metastable skyrmions in these materials is attributed to
+topological nature of the skyrmions as affected by structural and magnetic
+disorder. Magnetocrystalline anisotropy as well as magnetic disorder due to the
+frustrated Mn spins play crucial roles in giving rise to the observed change in
+helical states and corresponding skyrmion lattice form.",2008.05075v1
+2021-02-25,Magnetic order and crystalline electric field excitations of the quantum critical heavy fermion ferromagnet CeRh$_6$Ge$_4$,"CeRh$_6$Ge$_4$ is an unusual example of a stoichiometric heavy fermion
+ferromagnet, which can be cleanly tuned by hydrostatic pressure to a quantum
+critical point. In order to understand the origin of this anomalous behavior,
+we have characterized the magnetic ordering and crystalline electric field
+(CEF) scheme of this system. While magnetic Bragg peaks are not resolved in
+neutron powder diffraction, coherent oscillations are observed in zero-field
+$\mu$SR below $T_{\rm C}$, which are consistent with in-plane ferromagnetic
+ordering consisting of reduced Ce moments. From analyzing the magnetic
+susceptibility and inelastic neutron scattering, we propose a CEF-level scheme
+which accounts for the easy-plane magnetocrystalline anisotropy, where the low
+lying first excited CEF exhibits significantly stronger hybridization than the
+ground state. These results suggest that the orbital anisotropy of the ground
+state and low lying excited state doublets are important for realizing
+anisotropic electronic coupling between the $f$- and conduction electrons,
+which gives rise to the highly anisotropic hybridization observed in
+photoemission experiments.",2102.12788v2
+2021-03-30,Thermodynamic evidence of a second skyrmion lattice phase and tilted conical phase in Cu$_2$0SeO$_3$,"Precision measurements of the magnetization and ac susceptibility of
+Cu$_2$0SeO$_3$ are reported for magnetic fields along different
+crystallographic directions, focussing on the border between the conical and
+the field-polarized state for a magnetic field along the $\langle 100 \rangle$
+axis, complemented by selected specific heat data. Clear signatures of the
+emergence of a second skyrmion phase and a tilted conical phase are observed,
+as recently identified by means of small-angle neutron scattering. The
+low-temperature skyrmion phase displays strongly hysteretic phase boundaries,
+but no dissipative effects. In contrast, the tilted conical phase is
+accompanied by strong dissipation and higher-harmonic contributions, while the
+transition fields are essentially nonhysteretic. The formation of the second
+skyrmion phase and tilted conical phase are found to be insensitive to a
+vanishing demagnetization factor. A quantitative estimate of the temperature
+dependence of the magnetocrystalline anisotropy may be consistently inferred
+from the magnetization and the upper critical field and agrees well with a
+stabilization of the low-temperature skyrmion phase and tilted conical state by
+conventional cubic magnetic anisotropies.",2103.16238v2
+2021-05-11,On the connection between magnetic interactions and the spin-wave gap of the insulating phase of NaOsO$_{3}$,"The scenario of a metal-insulator transition driven by the onset of
+antiferromagnetic order in NaOsO$_3$ calls for a trustworthy derivation of the
+underlying effective spin Hamiltonian. To determine the latter we rely on {\it
+ab initio} electronic-structure calculations, linear spin-wave theory, and
+comparison to experimental data of the corresponding magnon spectrum. We arrive
+this way to Heisenberg couplings that are $\lesssim$45\% to$\lesssim$63\%
+smaller than values presently proposed in the literature and
+Dzyaloshinskii-Moriya interactions in the region of 15\% of the Heisenberg
+exchange $J$. These couplings together with the symmetric anisotropic exchange
+interaction and single-ion magnetocrystalline anisotropy successfully reproduce
+the magnon dispersion obtained by resonant inelastic X-ray scattering
+measurements. In particular, the spin-wave gap fully agrees with the measured
+one. We find that the spin-wave gap is defined from a subtle interplay between
+the single-ion anisotropy, the Dzyaloshinskii-Moriya exchange and the symmetric
+anisotropic exchange interactions. The results reported here underpin the
+local-moment description of NaOsO$_3$, when it comes to analyzing the magnetic
+excitation spectra. Interestingly, this comes about from a microscopic theory
+that describes the electron system as Bloch states, adjusted to a mean-field
+solution to Hubbard-like interactions.",2105.04893v2
+2021-11-25,Tunable gigahertz dynamics of low-temperature skyrmion lattice in a chiral magnet,"Recently, it has been shown that the chiral magnetic insulator Cu$_2$OSeO$_3$
+hosts skyrmions in two separated pockets in temperature and magnetic field
+phase space. It has also been shown that the predominant stabilization
+mechanism for the low-temperature skyrmion (LTS) phase is via the crystalline
+anisotropy, opposed to temperature fluctuations that stabilize the
+well-established high-temperature skyrmion (HTS) phase. Here, we report on a
+detailed study of LTS generation by field cycling, probed by GHz spin dynamics
+in Cu$_2$OSeO$_3$. LTSs are populated via a field cycling protocol with the
+static magnetic field applied parallel to the $\langle{100}\rangle$ crystalline
+direction of plate and cuboid-shaped bulk crystals. By analyzing
+temperature-dependent broadband spectroscopy data, clear evidence of
+low-temperature skyrmion excitations with clockwise (CW), counterclockwise
+(CCW), and breathing mode (BR) character at temperatures below $T$ = 40 K are
+shown. We find that the mode intensities can be tuned with the number of
+field-cycles below the saturation field. By tracking the resonance frequencies,
+we are able to map out the field-cycle-generated LTS phase diagram, from which
+we conclude that the LTS phase is distinctly separated from the
+high-temperature counterpart. We also study the mode hybridization between the
+dark CW and the BR modes as a function of temperature. By using two
+Cu$_2$OSeO$_3$ crystals with different shapes and therefore different
+demagnetization factors, together with numerical calculations, we unambiguously
+show that the magnetocrystalline anisotropy plays a central role for the mode
+hybridization.",2111.13004v1
+2022-06-10,Topological spiral magnetism in the Weyl semimetal SmAlSi,"Weyl electrons are intensely studied due to novel charge transport phenomena
+such as chiral anomaly, Fermi arcs, and photogalvanic effect. Recent
+theoretical works suggest that Weyl electrons can also participate in magnetic
+interactions, and the Weyl-mediated indirect exchange coupling between local
+moments is proposed as a new mechanism of spiral magnetism that involves chiral
+electrons. Despite reports of incommensurate and non-collinear magnetic
+ordering in Weyl semimetals, an actual spiral order has remained hitherto
+undetected. Here, we present evidence of Weyl-mediated spiral magnetism in
+SmAlSi from neutron diffraction, transport, and thermodynamic data. We show
+that the spiral order in SmAlSi results from the nesting between topologically
+non-trivial Fermi pockets and weak magnetocrystalline anisotropy, unlike
+related materials (Ce,Pr,Nd)AlSi, where a strong anisotropy prevents the spins
+from freely rotating. We map the magnetic phase diagram of SmAlSi and reveal an
+A-phase where topological magnetic excitations may exist. This is corroborated
+by the observation of a topological Hall effect within the A-phase.",2206.05121v1
+2022-11-24,Unravelling the role of Sm 4f electrons in the magnetism of SmFeO$_3$,"Magnetic rare-earth orthoferrites $R$FeO$_3$ host a variety of functional
+properties from multiferroicity and strong magnetostriction, to
+spin-reorientation transitions and ultrafast light-driven manipulation of
+magnetism, which can be exploited in spintronics and next-generation devices.
+Among these systems, SmFeO$_3$ is attracting a particular interest for its rich
+phase diagram and the high temperature Fe-spin magnetic transitions, which
+combines with a very low temperature and as yet unclear Sm-spin ordering.
+Various experiments suggest that the interaction between the Sm and Fe magnetic
+moments (further supported by the magnetic anisotropy), is at the origin of the
+complex cascade of transitions, but a conclusive and clear picture has not yet
+been reached. In this work, by means of comprehensive first-principles
+calculations, we unravel the role of the magnetic Sm ions in the Fe-spin
+reorientation transition and in the detected anomalies in the lattice
+vibrational spectrum, which are a signature of a relevant spin-phonon coupling.
+By including both Sm-$f$ electrons and non-collinear magnetism, we find
+frustrated and anisotropic Sm interactions, and a large magnetocrystalline
+anisotropy mediated by the SOC of the Sm-$4f$ electrons, which drive the
+complex magnetic properties and phase diagram of SmFeO$_3$.",2211.13528v1
+2023-02-10,Correlation-driven topological transition in Janus VSiGeP2As2,"The appearance of intrinsic ferromagnetism in 2D materials opens the
+possibility of investigating the interplay between magnetism and topology. The
+magnetic anisotropy energy (MAE) describing the easy axis for magnetization in
+a particular direction is an important yardstick for nanoscale applications.
+Here, the first-principles approach is used to investigate the electronic band
+structures, the strain dependence of MAE in pristine VSi2Z4 (Z=P, As) and its
+Janus phase VSiGeP2As2 and the evolution of the topology as a function of the
+Coulomb interaction. In the Janus phase the compound presents a breaking of the
+mirror symmetry, which is equivalent to having an electric field, and the
+system can be piezoelectric. It is revealed that all three monolayers exhibit
+ferromagnetic ground state ordering, which is robust even under biaxial
+strains. A large value of coupling J is obtained, and this, together with the
+magnetocrystalline anisotropy, will produce a large critical temperature. We
+found an out-of-plane (in-plane) magnetization for VSi2P4 (VSi2As4), while
+in-plane magnetization for VSiGeP2As2. Furthermore, we observed a
+correlation-driven topological transition in the Janus VSiGeP2As2. Our analysis
+of these emerging pristine and Janus-phased magnetic semiconductors opens
+prospects for studying the interplay between magnetism and topology in
+two-dimensional materials.",2302.05146v2
+2023-02-23,The influence of crystalline electric field on the magnetic properties of CeCd3X3 (X = P and As),"CeCd$_3$P$_3$ and CeCd$_3$As$_3$ compounds adopt the hexagonal
+ScAl$_3$C$_3$-type structure, where magnetic Ce ions on a triangular lattice
+order antiferromagnetically below $T_\text{N} \sim$0.42~K. Their crystalline
+electric field (CEF) level scheme has been determined by fitting magnetic
+susceptibility curves, magnetization isotherms, and Schottky anomalies in
+specific heat. The calculated results, incorporating the CEF excitation, Zeeman
+splitting, and molecular field, are in good agreement with the experimental
+data. The CEF model, with Ce$^{3+}$ ions in a trigonal symmetry, explains the
+strong easy-plane magnetic anisotropy that has been observed in this family of
+materials. A detailed examination of the CEF parameters suggests that the
+fourth order CEF parameter $B_{4}^{3}$ is responsible for the strong CEF
+induced magnetocrystalline anisotropy, with a large $ab$-plane moment and a
+small $c$-axis moment. The reliability of our CEF analysis is assessed by
+comparing the current study with earlier reports of CeCd$_{3}$As$_{3}$. For
+both CeCd$_{3}X_{3}$ ($X$ = P and As) compounds, less than 40 \% of $R\ln(2)$
+magnetic entropy is recovered by $T_\text{N}$ and full $R\ln(2)$ entropy is
+achieved at the Weiss temperature $\theta_{p}$. Although the observed magnetic
+entropy is reminiscent of delocalized 4$f$-electron magnetism with significant
+Kondo screening, the electrical resistivity of these compounds follows a
+typical metallic behavior. Measurements of thermoelectric power further
+validate the absence of Kondo contribution in CeCd$_{3}X_{3}$.",2302.11714v1
+2023-02-28,"Epitaxial growth and characterization of (001) [NiFe/M]$_{20}$ (M = Cu, CuPt and Pt) superlattices","We present optimization of [(15 $\unicode{x212B}$) Ni$_{80}$Fe$_{20}$/(5
+$\unicode{xC5}$) M]$_{20}$ single crystal multilayers on (001) MgO, with M
+being Cu, Cu$_{50}$Pt$_{50}$ and Pt. These superlattices were characterized by
+high-resolution X-ray reflectivity (XRR) and diffraction (XRD) as well as polar
+mapping of important crystal planes. It is shown that cube on cube epitaxial
+relationship can be obtained when depositing at the substrate temperature of
+100 $^\circ$C regardless of the lattice mismatch (5% and 14% for Cu and Pt,
+respectively). At lower substrate temperatures poly-crystalline multilayers
+were obtained while at higher substrate temperatures {111} planes appear at
+$\sim$10$^\circ$ off normal to the film plane. It is also shown that as the
+epitaxial strain increases, the easy magnetization axis rotates towards the
+direction that previously was assumed to be harder, i.e. from [110] to [100],
+and eventually further increase in the strain makes the magnetic hysteresis
+loops isotropic in the film plane. Higher epitaxial strain is also accompanied
+with increased coercivity values. Thus, the effect of epitaxial strain on the
+magnetocrystalline anisotropy is much larger than what was observed previously
+in similar, but polycrystalline samples with uniaxial anisotropy (Kateb et al.
+2021).",2302.14745v1
+2023-05-08,Large magnetocaloric effect in the kagome ferromagnet Li$_9$Cr$_3$(P$_2$O$_7$)$_3$(PO$_4$)$_2$,"Single-crystal growth, magnetic properties, and magnetocaloric effect of the
+$S = 3/2$ kagome ferromagnet Li$_9$Cr$_3$(P$_2$O$_7$)$_3$(PO$_4$)$_2$
+(trigonal, space group: $P\bar{3}c1$) are reported. Magnetization data suggest
+dominant ferromagnetic intra-plane coupling with a weak anisotropy and the
+onset of ferromagnetic ordering at $T_{\rm C} \simeq 2.6$ K. Microscopic
+analysis reveals a very small ratio of interlayer to intralayer ferromagnetic
+couplings ($J_{\perp}/J \simeq 0.02$). Electron spin resonance data suggest the
+presence of short-range correlations above $T_{\rm C}$ and confirms
+quasi-two-dimensional character of the spin system. A large magnetocaloric
+effect characterized by isothermal entropy change of $-\Delta S_{\rm m}\simeq
+31$ J kg$^{-1}$ K$^{-1}$ and adiabatic temperature change of $-\Delta T_{\rm
+ad}\simeq 9$ K upon a field sweep of 7 T is observed around $T_{\rm C}$. This
+leads to a large relative cooling power of $RCP \simeq 284$ J kg$^{-1}$. The
+large magnetocaloric effect, together with negligible hysteresis render
+Li$_9$Cr$_3$(P$_2$O$_7$)$_3$(PO$_4$)$_2$ a promising material for magnetic
+refrigeration at low temperatures. The magnetocrystalline anisotropy constant
+$K \simeq -7.42 \times 10^4$ erg cm$^{-3}$ implies that the compound is an
+easy-plane type ferromagnet with the hard axis normal to the $ab$-plane,
+consistent with the magnetization data.",2305.04744v1
+2023-06-21,"First-principles prediction of structural, magnetic properties of Cr-substituted strontium hexaferrite, and its site preference","To investigate the structural and magnetic properties of Cr-doped M-type
+strontium hexaferrite (SrFe$_{12}$O$_{19}$) with x = (0.0, 0.5, 1.0), we
+perform first-principles total-energy calculations relied on density functional
+theory. Based on the calculation of the substitution energy of Cr in strontium
+hexaferrite and formation probability analysis, we conclude that the doped Cr
+atoms prefer to occupy the 2a, 12k, and 4f$_{2}$ sites which is in good
+agreement with the experimental findings. Due to Cr$^{3+}$ ion moment, 3
+{$\mu_B$}, smaller than that of Fe$^{3+}$ ion, 5 {$\mu_B$}, saturation
+magnetization (M$_{s}$) reduce rapidly as the concentration of Cr increases in
+strontium hexaferrite. The magnetic anisotropic field $\left(H_{a}\right)$
+rises with an increasing fraction of Cr despite a significant reduction of
+magnetization and a slight increase of magnetocrystalline anisotropy
+$\left(K_{1}\right)$.The cause for the rise in magnetic anisotropy field
+$\left(H_{a}\right)$ with an increasing fraction of Cr is further emphasized by
+our formation probability study. Cr$^{3+}$ ions prefer to occupy the 2a sites
+at lower temperatures, but as the temperature rises, it is more likely that
+they will occupy the 12k site. Cr$^{3+}$ ions are more likely to occupy the 12k
+site than the 2a site at a specific annealing temperature (>700{\deg}C).",2306.11952v1
+2023-11-22,Engineering magnetic domain wall energies in multiferroic BiFeO$_3$ via epitaxial strain,"Epitaxial strain has emerged as a powerful tool to tune magnetic and
+ferroelectric properties in functional materials such as in multiferroic
+perovskite oxides. Here, we use first-principles calculations to explore the
+evolution of magnetic interactions in the antiferromagnetic multiferroic
+BiFeO$_3$ (BFO), one of the most promising multiferroics for future technology.
+The epitaxial strain in BFO(001) oriented film is varied between
+$\varepsilon_{xx,yy}$ $\in$ $[-2\%, +2\%]$. We find that both strengths of the
+exchange interaction and Dzyaloshinskii-Moriya interaction (DMI) decrease
+linearly from compressive to tensile strain whereas the uniaxial
+magnetocrystalline anisotropy follows a parabolic behavior which lifts the
+energy degeneracy of the (111) easy plane of bulk BFO. From the trends of the
+magnetic interactions we can explain the destruction of cycloidal order in
+compressive strain as observed in experiments due to the increasing anisotropy
+energy. For tensile strain, we predict that the ground state remains unchanged
+as a function of strain. By using the domain wall (DW) energy, we envision the
+region where isolated chiral magnetic texture might occur as function of strain
+i.e. where the DW and the spin spiral energy are equal. This transition between
+$-1.5\%$ and $-0.5\%$ of strain should allow topologically stable magnetic
+states such as antiferromagnetic skyrmions and merons to occur. Hence, our work
+should trigger experimental and theoretical investigations in this range of
+strain.",2311.13215v1
+2024-03-01,Spin current control of magnetism,"Exploring novel strategies to manipulate the order parameter of magnetic
+materials by electrical means is of great importance, not only for advancing
+our understanding of fundamental magnetism, but also for unlocking potential
+practical applications. A well-established concept to date uses gate voltages
+to control magnetic properties, such as saturation magnetization, magnetic
+anisotropies, coercive field, Curie temperature and Gilbert damping, by
+modulating the charge carrier population within a capacitor structure. Note
+that the induced carriers are non-spin-polarized, so the control via the
+electric-field is independent of the direction of the magnetization. Here, we
+show that the magnetocrystalline anisotropy (MCA) of ultrathin Fe films can be
+reversibly modified by a spin current generated in Pt by the spin Hall effect.
+The effect decreases with increasing Fe thickness, indicating that the origin
+of the modification can be traced back to the interface. Uniquely, the change
+in MCA due to the spin current depends not only on the polarity of the charge
+current but also on the direction of magnetization, i.e. the change in MCA has
+opposite sign when the direction of magnetization is reversed. The control of
+magnetism by the spin current results from the modified exchange splitting of
+majority- and minority-spin bands, and differs significantly from the
+manipulation by gate voltages via a capacitor structure, providing a
+functionality that was previously unavailable and could be useful in advanced
+spintronic devices.",2403.00709v1
+2016-03-01,"Magnetic properties of Fe$_5$SiB$_2$ and its alloys with P, S, and Co","Fe$_5$SiB$_2$ has been synthesized and magnetic measurements have been
+carried out, revealing that M$_{\text{sat}}$ = 0.92 MA/m at T = 300 K. The M vs
+T curve shows a broad peak around T = 160 K. The anisotropy constant, K$_1$,
+estimated at T = 300 K, is 0.25 MJ/m$^3$. Theoretical analysis of Fe$_5$SiB$_2$
+system has been carried out and extended to the full range of
+Fe$_5$Si$_{1-x}$P$_x$B$_2$, Fe$_5$P$_{1-x}$S$_x$B$_2$, and
+(Fe$_{1-x}$Co$_x$)$_5$SiB$_2$ compositions. The electronic band structures have
+been calculated using the Full-Potential Local-Orbital Minimum-Basis Scheme
+(FPLO-14). The calculated total magnetic moments are 9.20, 9.15, 9.59 and
+2.42$\mu_B$ per formula units of Fe$_5$SiB$_2$, Fe$_5$PB$_2$, Fe$_5$SB$_2$, and
+Co$_5$SiB$_2$, respectively. In agreement with experiment, magnetocrystalline
+anisotropy energies (MAE's) calculated for T = 0 K changes from a negative
+(easy-plane) anisotropy -0.28 MJ/m$^3$ for Fe$_5$SiB$_2$ to the positive
+(easy-axis) anisotropy 0.35 MJ/m$^3$ for Fe$_5$PB$_2$. Further increase of the
+number of p-electrons in Fe$_5$P$_{1-x}$S$_x$B$_2$ leads to an increase of MAE
+up to 0.77 MJ/m$^3$ for the hypothetical Fe$_5$P$_{0.4}$S$_{0.6}$B$_2$
+composition. Volume variation and fixed spin moment calculations (FSM)
+performed for Fe$_5$SiB$_2$ show an inverse relation between MAE and magnetic
+moment in the region down to about 15\% reduction of the spin moment. The
+alloying of Fe$_5$SiB$_2$ with Co is proposed as a practical realization of
+magnetic moment reduction, which ought to increase MAE. MAE calculated in
+virtual crystal approximation (VCA) for a full range of
+(Fe$_{1-x}$Co$_x$)$_5$SiB$_2$ compositions reaches the maximum value of 1.16
+MJ/m$^3$ at Co concentration x = 0.3, with the magnetic moment 7.75$\mu_B$ per
+formula unit. Thus, (Fe$_{0.7}$Co$_{0.3}$)$_5$SiB$_2$ is suggested as a
+candidate for a rare-earth free permanent magnet.",1603.00253v1
+2018-10-05,Magnetic anisotropy and spin-polarized two-dimensional electron gas in the van der Waals ferromagnet Cr$_2$Ge$_2$Te$_6$,"We report a comprehensive experimental investigation on the magnetic
+anisotropy in bulk single crystals of Cr$_2$Ge$_2$Te$_6$, a
+quasi-two-dimensional ferromagnet belonging to the family of magnetic layered
+transition metal trichalcogenides that have attracted recently a big deal of
+interest with regard to the fundamental and applied aspects of two-dimensional
+magnetism. For this purpose electron spin resonance (ESR) and ferromagnetic
+resonance (FMR) measurements have been carried out over a wide frequency and
+temperature range. A gradual change in the angular dependence of the ESR
+linewidth at temperatures above the ferromagnetic transition temperature
+$T_{\rm c}$ reveals the development of two-dimensional spin correlations in the
+vicinity of $T_{\rm c}$ thereby proving the intrinsically low-dimensional
+character of spin dynamics in Cr$_2$Ge$_2$Te$_6$. Angular and frequency
+dependent measurements in the ferromagnetic phase clearly show an easy-axis
+type anisotropy of this compound. Furthermore, these experiments are compared
+with simulations based on a phenomenological approach, which takes into account
+results of static magnetization measurements as well as high temperature $g$
+factors obtained from ESR spectroscopy in the paramagnetic phase. As a result
+the determined magnetocrystalline anisotropy energy density (MAE) $K_U$ is
+$(0.48 \pm 0.02) \times10^6$ erg/cm$^3$. This analysis is complemented by
+density functional calculations which yield the experimental MAE value for a
+particular value of the electronic correlation strength $U$. The analysis of
+the electronic structure reveals that the low-lying conduction band carries
+almost completely spin-polarized, quasi-homogeneous, two-dimensional states.",1810.02560v3
+2020-02-01,Random magnetic anisotropy driven transitions in layered perovskite LaSrCoO$_4$,"Attempts to unravel the nature of magnetic ordering in LaSrCoO$_4$
+(Co$^{3+}$), a compound intermediate between antiferromagnetic (AFM)
+La$_2$CoO$_4$ (Co$^{2+}$) and ferromagnetic (FM) Sr$_2$CoO$_4$ (Co$^{4+}$),
+have met with a limited success so far. In this report, the results of a
+thorough investigation of dc magnetization and ac susceptibility (ACS) in
+single-phase LaSrCoO$_4$ provide clinching evidence for a thermodynamic
+paramagnetic (PM) - ferromagnetic (FM) phase transition at T$_{c}$ = 220.5 K,
+followed at lower temperature (T$_{g}$ = 7.7 K) by a transition to the cluster
+spin glass (CSG) state. Analysis of the low-field Arrott plot isotherms, in the
+critical region near T$_{c}$, in terms of the Aharony-Pytte scaling equation of
+state clearly establishes that the PM-FM transition is basically driven by
+random magnetic anisotropy (RMA). For temperatures below $\approx$ 30 K, large
+enough RMA destroys long-range FM order by breaking up the infinite FM network
+into FM clusters of finite size and leads to the formation of a CSG state at
+temperatures T $\lesssim$ 8 K by promoting freezing of finite FM clusters in
+random orientations. Increasing strength of the single-ion magnetocrystalline
+anisotropy (and hence RMA) with decreasing temperature is taken to reflect an
+increase in the number of low-spin (LS) Co$^{3+}$ ions at the expense of that
+of high-spin (HS) Co$^{3+}$ ions. At intermediate temperatures (30 K $\lesssim
+T \lesssim$ 180 K), spin dynamics has contributions from the infinite FM
+network (fast relaxation governed by a single anisotropy energy barrier) and
+finite FM clusters (extremely slow stretched exponential relaxation due to
+hierarchical energy barriers).",2002.00135v3
+2020-09-02,New highly-anisotropic Rh-based Heusler compound for magnetic recording,"The development of high-density magnetic recording media is limited by the
+superparamagnetism in very small ferromagnetic crystals. Hard magnetic
+materials with strong perpendicular anisotropy offer stability and high
+recording density. To overcome the difficulty of writing media with a large
+coercivity, heat assisted magnetic recording (HAMR) has been developed, rapidly
+heating the media to the Curie temperature Tc before writing, followed by rapid
+cooling. Requirements are a suitable Tc, coupled with anisotropic thermal
+conductivity and hard magnetic properties. Here we introduce Rh2CoSb as a new
+hard magnet with potential for thin film magnetic recording. A
+magnetocrystalline anisotropy of 3.6 MJm-3 is combined with a saturation
+magnetization of {\mu}0Ms = 0.52 T at 2 K (2.2 MJm-3 and 0.44 T at
+room-temperature). The magnetic hardness parameter of 3.7 at room temperature
+is the highest observed for any rare-earth free hard magnet. The anisotropy is
+related to an unquenched orbital moment of 0.42 {\mu}B on Co, which is
+hybridized with neighbouring Rh atoms with a large spin-orbit interaction.
+Moreover, the pronounced temperature-dependence of the anisotropy that follows
+from its Tc of 450 K, together with a high thermal conductivity of 20 Wm-1K-1,
+makes Rh2CoSb a candidate for development for heat assisted writing with a
+recording density in excess of 10 Tb/in2.",2009.01034v1
+2017-03-16,Discovery of intrinsic ferromagnetism in 2D van der Waals crystals,"It has been long hoped that the realization of long-range ferromagnetic order
+in two-dimensional (2D) van der Waals (vdW) crystals, combined with their rich
+electronic and optical properties, would open up new possibilities for
+magnetic, magnetoelectric and magneto-optic applications. However, in 2D
+systems, the long-range magnetic order is strongly hampered by thermal
+fluctuations which may be counteracted by magnetic anisotropy, according to the
+Mermin-Wagner theorem. Prior efforts via defect and composition engineering,
+and proximity effect only locally or extrinsically introduce magnetic
+responses. Here we report the first experimental discovery of intrinsic
+long-range ferromagnetic order in pristine Cr2Ge2Te6 atomic layers by scanning
+magneto-optic Kerr microscopy. In such a 2D vdW soft ferromagnet, for the first
+time, an unprecedented control of transition temperature of ~ 35% - 57%
+enhancement is realized via surprisingly small fields (<= 0.3 Tesla in this
+work), in stark contrast to the stiffness of the transition temperature to
+magnetic fields in the three-dimensional regime. We found that the small
+applied field enables an effective anisotropy far surpassing the tiny
+magnetocrystalline anisotropy, opening up a sizable spin wave excitation gap.
+Confirmed by renormalized spin wave theory, we explain the phenomenon and
+conclude that the unusual field dependence of transition temperature
+constitutes a hallmark of 2D soft ferromagnetic vdW crystals. Our discovery of
+2D soft ferromagnetic Cr2Ge2Te6 presents a close-to-ideal 2D Heisenberg
+ferromagnet for studying fundamental spin behaviors, and opens the door for
+exploring new applications such as ultra-compact spintronics.",1703.05753v1
+2023-03-21,Robust intralayer antiferromagnetism and tricriticality in a van der Waals compound: VBr3 case,"We studied magnetic states and phase transitions in the van der Waals
+antiferromagnet VBr3 by specific heat and magnetization measurements of single
+crystals in high magnetic fields and by ab initio density functional theory
+calculations focused on exchange interactions. The magnetization behavior
+resembles Ising antiferromagnets with magnetic moments kept in the out-of-plane
+direction by strong uniaxial magnetocrystalline anisotropy. The out-of-plane
+magnetic field induces a spin-flip metamagnetic transition, which is of
+first-order type at low temperatures while at higher temperatures the
+transition becomes continuous. The first-order and continuous transition
+segments in the field-temperature phase diagram meet at a tricritical point at
+= 12 K. The magnetization response to the in-plane field manifests a continuous
+spin-flop transition, which at 2 K terminates at a field mu0Hc = 27 T that can
+serve as an estimate of the anisotropy field in VBr3. The magnetization curves
+above the metamagnetic transition saturate at the same value of magnetic moment
+musat = 1.2 muB/f.u., which is much smaller than the spin-only (S = 1) moment
+of the V3+ ion. The reduced moment can be explained by the existence of a
+significant orbital magnetic moment antiparallel to the spin. The orbital
+moment is a key ingredient of a mechanism responsible for the observed large
+anisotropy. The exact energy evaluation of possible magnetic orders
+unambiguously shows that the magnetic ground state of VBr3 is the intralayer
+zigzag antiferromagnetic order that renders the antiferromagnetic ground state
+significantly more stable against the spin-flip transition than the other
+options. The calculations also predict that a minimal distortion of the Br ion
+sublattice causes a radical change of the orbital occupation in the ground
+state, connected with the formation of the orbital moment and the stability of
+magnetic order.",2303.11794v2
+2022-03-11,Hard ferromagnetism down to the thinnest limit of iron-intercalated tantalum disulfide,"Two-dimensional (2D) magnetic crystals hold promise for miniaturized and
+ultralow power electronic devices that exploit spin manipulation. In these
+materials, large, controllable magnetocrystalline anisotropy is a prerequisite
+for the stabilization and manipulation of long-range magnetic order. In known
+2D magnetic crystals, relatively weak magnetocrystalline anisotropy results in
+typically soft ferromagnetism. Here, we demonstrate that ferromagnetic order
+persists down to the thinnest limit of Fe$_x$TaS$_2$ (Fe-intercalated bilayer
+2H-TaS$_2$) with giant coercivities up to 3 tesla. We prepare Fe-intercalated
+TaS$_2$ by chemical intercalation of van der Waals layered 2H-TaS$_2$ crystals
+and perform variable-temperature quantum transport, transmission electron
+microscopy, and confocal Raman spectroscopy measurements to shed new light on
+the coupled effects of dimensionality, degree of intercalation, and intercalant
+order/disorder on the hard ferromagnetic behavior of Fe$_x$TaS$_2$. More
+generally, we show that chemical intercalation gives access to a rich synthetic
+parameter space for low-dimensional magnets, in which magnetic properties can
+be tailored by the choice of the host material and intercalant identity/amount,
+in addition to the manifold distinctive degrees of freedom available in
+atomically thin, van der Waals crystals.",2203.05747v2
+2007-03-22,Orbital contribution to the magnetic properties of iron as a function of dimensionality,"The orbital contribution to the magnetic properties of Fe in systems of
+decreasing dimensionality (bulk, surfaces, wire and free clusters) is
+investigated using a tight-binding hamiltonian in an $s, p,$ and $d$ atomic
+orbital basis set including spin-orbit coupling and intra-atomic electronic
+interactions in the full Hartree-Fock (HF) scheme, i.e., involving all the
+matrix elements of the Coulomb interaction with their exact orbital dependence.
+Spin and orbital magnetic moments and the magnetocrystalline anisotropy energy
+(MAE) are calculated for several orientations of the magnetization. The results
+are systematically compared with those of simplified hamiltonians which give
+results close to those obtained from the local spin density approximation. The
+full HF decoupling leads to much larger orbital moments and MAE which can reach
+values as large as 1$\mu_B$ and several tens of meV, respectively, in the
+monatomic wire at the equilibrium distance. The reliability of the results
+obtained by adding the so-called Orbital Polarization Ansatz (OPA) to the
+simplified hamiltonians is also discussed. It is found that when the spin
+magnetization is saturated the OPA results for the orbital moment are in
+qualitative agreement with those of the full HF model. However there are large
+discrepancies for the MAE, especially in clusters. Thus the full HF scheme must
+be used to investigate the orbital magnetism and MAE of low dimensional
+systems.",0703576v1
+2007-07-16,Magnetodipolar interlayer interaction effect on the magnetization dynamics of a trilayer square element with the Landau domain structure,"We present a detailed numerical simulation study of the effects caused by the
+magnetodipolar interaction between ferromagnetic (FM) layers of a trilayer
+magnetic nanoelement on its magnetization dynamics. As an example we use a
+Co/Cu/Ni80Fe20 element with a square lateral shape where the magnetization of
+FM layers forms a closed Landau-like domain pattern. First we show that when
+the thickness of the non-magnetic (NM) spacer is in the technology relevant
+region h ~ 10 nm, magnetodipolar interaction between 90o Neel domain walls in
+FM layers qualitatively changes the equilibrium magnetization state of these
+layers. In the main of the paper we compare the magnetization dynamics induced
+by a sub-nsec field pulse in a single-layer Ni80Fe20 (Py) element and in the
+Co/Cu/Py trilayer element. Here we show that (i) due to the spontaneous
+symmetry breaking of the Landau state in the FM/NM/FM trilayer its domains and
+domain walls oscillate with different frequencies and have different spatial
+oscillation patterns; (ii) magnetization oscillations of the trilayer domains
+are strongly suppressed due to different oscillation frequencies of domains in
+Co and Py; (iii) magnetization dynamics qualitatively depends on the relative
+rotation sense of magnetization states in Co and Py layers and on the
+magnetocrystalline anisotropy kind of Co crystallites. Finally we discuss the
+relation of our findings with experimental observations of magnetization
+dynamics in magnetic trilayers, performed using the element-specific
+time-resolved X-ray microscopy.",0707.2344v1
+2008-01-29,"Anisotropic magnetization studies of $R_2 Co Ga_8$ (R = Gd, Tb, Dy, Ho, Er, Tm, Y and Lu) single crystals","Single crystals of R$_2$CoGa$_8$ series of compounds were grown, for the
+first time, by high temperature solution growth (flux) method. These compounds
+crystallize in a tetragonal crystal structure with the space group $P4/mmm$. It
+has been found that R$_2$CoGa$_8$ phase forms only with the heavier rare
+earths, starting from Gd with a relatively large $c/a$ ratio of $\approx$ 2.6.
+The resultant anisotropic magnetic properties of the compounds were
+investigated along the two principal crystallographic directions of the crystal
+viz., along [100] and [001]. The nonmagnetic compounds Y$_2$CoGa$_8$ and
+Lu$_2$CoGa$_8$ show diamagnetic behavior down to the lowest temperature (1.8 K)
+pointing out the non-magnetic nature of Co in these compounds and a relatively
+low density of electronic states at the Fermi level. Compounds with the
+magnetic rare earths order antiferromagnetically at temperatures lower than 30
+K. The easy axis of magnetization for R$_2$CoGa$_8$ (R = Tb, Dy and Ho) is
+found to be along the [001] direction and it changes to [100] direction for
+Er$_2$CoGa$_8$ and Tm$_2$CoGa$_8$. The magnetization behavior is analyzed on
+the basis of crystalline electric field (CEF) model. The estimated crystal
+field parameters explains the magnetocrystalline anisotropy in this series of
+compounds.",0801.4518v1
+2009-09-09,Tuning of crystal structure and magnetic properties by exceptionally large epitaxial strains,"Huge deformations of the crystal lattice can be achieved in materials with
+inherent structural instability by epitaxial straining. By coherent growth on
+seven different substrates the in-plane lattice constants of 50 nm thick
+Fe70Pd30 films are continuously varied. The maximum epitaxial strain reaches
+8,3 % relative to the fcc lattice. The in-plane lattice strain results in a
+remarkable tetragonal distortion ranging from c/abct = 1.09 to 1.39, covering
+most of the Bain transformation path from fcc to bcc crystal structure. This
+has dramatic consequences for the magnetic key properties. Magnetometry and
+X-ray circular dichroism (XMCD) measurements show that Curie temperature,
+orbital magnetic moment, and magnetocrystalline anisotropy are tuned over broad
+ranges.",0909.1728v3
+2009-11-18,Structurally-driven magnetic state transition of biatomic Fe chains on Ir(001),"Using first-principles calculations, we demonstrate that the magnetic
+exchange interaction and the magnetocrystalline anisotropy of biatomic Fe
+chains grown in the trenches of the 5x1 reconstructed Ir(001) surface depend
+sensitively on the atomic arrangement of the Fe atoms. Two structural
+configurations have been considered which are suggested from recent
+experiments. They differ by the local symmetry and the spacing between the two
+strands of the biatomic Fe chain. Since both configurations are very close in
+total energy they may coexist in experiment. We have investigated collinear
+ferro- and antiferromagnetic solutions as well as a collinear state with two
+moments in one direction and one in the opposite direction (up-down-up-state).
+For the structure with a small interchain spacing, there is a strong exchange
+interaction between the strands and the ferromagnetic state is energetically
+favorable. In the structure with larger spacing, the two strands are
+magnetically nearly decoupled and exhibit antiferromagnetic order along the
+chain. In both cases, due to hybridization with the Ir substrate the exchange
+interaction along the chain axis is relatively small compared to freestanding
+biatomic iron chains. The easy magnetization axis of the Fe chains also
+switches with the structural configuration and is out-of-plane for the
+ferromagnetic chains with small spacing and along the chain axis for the
+antiferromagnetic chains with large spacing between the two strands. Calculated
+scanning tunneling microscopy images and spectra suggest the possibility to
+experimentally distinguish between the two structural and magnetic
+configurations.",0911.3526v1
+2010-01-25,Solution growth of Ce-Pd-In single crystals: characterization of the heavy-fermion superconductor Ce2PdIn8,"Solution growth of single crystals of the recently reported new compound
+Ce2PdIn8 was investigated. When growing from a stoichiometry in a range 2:1:20
+- 2:1:35, single crystals of CeIn3 covered by a thin (~50 um)
+single-crystalline layer of Ce2PdIn8 were mostly obtained. Using palladium
+richer compositions the thickness of the Ce2PdIn8 layers were increased, which
+allowed mechanical extraction of single-phase slabs of the desired compound
+suitable for a thorough study of magnetism and superconductivity. In some
+solution growth products also CePd3In6 (LaNi3In6 - type of structure) and
+traces of phases with the stoichiometry CePd2In7, Ce1.5Pd1.5In7 (determined
+only by EDX) have been identified. Magnetic measurements of the Ce2PdIn8 single
+crystals reveal paramagnetic behaviour of the Ce3+ ions with significant
+magnetocrystalline anisotropy. Above 70 K the magnetic susceptibility follows
+the Curie-Weiss law with considerably different values of the paramagnetic
+Curie temperature, for the magnetic field applied along the a- (-90 K) and
+c-(-50 K) axis. Below the reported critical temperature for superconductivity
+Tc (0.69 K) the electrical resistivity drops to zero. Comparative measurements
+of the electrical resistivity, heat capacity and AC susceptibility of several
+crystals reveal that the superconducting transition is strongly
+sample-dependent.",1001.4403v1
+2013-03-14,Spin-torque effects in thermally assisted magnetization reversal: Method of statistical moments,"Thermal fluctuations of nanomagnets driven by spin-polarized currents are
+treated via the Landau-Lifshitz-Gilbert equation generalized to include both
+the random thermal noise field and the Slonczewski spin-transfer torque term.
+By averaging this stochastic (Langevin) equation over its realizations, the
+explicit infinite hierarchy of differential-recurrence relations for
+statistical moments (averaged spherical harmonics) is derived for arbitrary
+demagnetizing factors and magnetocrystalline anisotropy for the generic
+nanopillar model of a spin-torque device comprising two ferromagnetic strata
+representing the free and fixed layers and a nonmagnetic conducting spacer all
+sandwiched between two ohmic contacts. The influence of thermal fluctuations
+and spin-transfer torques on relevant switching characteristics, such as the
+stationary magnetization, the magnetization reversal time, etc., is calculated
+by solving the hierarchy for wide ranges of temperature, damping, external
+magnetic field, and spin-polarized current indicating new spin-torque effects
+in the thermally assisted magnetization reversal comprising several orders of
+magnitude. In particular, a pronounced dependence of the switching
+characteristics on the directions of the external magnetic field and the spin
+polarization exists.",1303.3476v4
+2014-08-18,Unquenched $e_g^1$ orbital moment in the Mott insulating antiferromagnet KOsO4,"Applying the correlated electronic structure method based on density
+functional theory plus the Hubbard $U$ interaction, we have investigated the
+tetragonal scheelite structure Mott insulator KOsO$_4$, whose $e_g^1$
+configuration should be affected only slightly by spin-orbit couping (SOC). The
+method reproduces the observed antiferromagnetic Mott insulating state,
+populating the Os $d_{z^2}$ majority orbital. The quarter-filled $e_g$ manifold
+is characterized by a symmetry breaking due to the tetragonal structure, and
+the Os ion shows a crystal field splitting $\Delta_{cf}$ = 1.7 eV from the
+$t_{2g}$ complex, which is relatively small considering the high formal
+oxidation state Os$^{7+}$. The small magnetocrystalline anisotropy before
+including correlation (i.e., in the metallic state) is increased by more than
+an order of magnitude in the Mott-insulating state, a result of a strong
+interplay between large SOC and a strong correlation. In contrast to
+conventional wisdom that the $e_g$ complex will not support orbital magnetism,
+we find that for the easy axis [100] direction the substantial Os orbital
+moment $M_L\approx-0.2 \mu_B$ compensates half of the Os spin moment $M_S$ =
+0.4$\mu_B$. The origin of the orbital moment is analyzed and understood in
+terms of additional spin-orbital lowering of symmetry, and beyond that due to
+structural distortion, for magnetization along [100]. Further interpretation is
+assisted by analysis of the spin density and the Wannier function with SOC
+included.",1408.4078v2
+2015-01-09,Single crystal study of layered U$_{n}$RhIn$_{3n+2}$ materials: case of the novel U$_{2}$RhIn$_{8}$ compound,"We report on the single crystal properties of the novel U$_{2}$RhIn$_{8}$
+compound studied in the context of parent URhIn$_{5}$ and UIn$_{3}$ systems.
+The compounds were prepared by In self-flux method. U$_{2}$RhIn$_{8}$ adopts
+the Ho$_{2}$CoGa$_{8}$-type structure with lattice parameters a $= 4.6056(6)$
+\AA\ and c $= 11.9911(15)$ \AA. The behavior of U$_{2}$RhIn$_{8}$ strongly
+resembles that of the related URhIn$_{5}$ and UIn$_{3}$ with respect to
+magnetization, specific heat and resistivity except for magnetocrystalline
+anisotropy developing with lowering dimensionality in the series UIn$_{3}$ vs.
+U$_{2}$RhIn$_{8}$ and URhIn$_{5}$. U$_{2}$RhIn$_{8}$ orders
+antiferromagnetically below T$_{\textrm{N}}$ $= 117$ K and exhibits a slightly
+enhanced Sommerfeld coefficient $\gamma = 47$ mJ$\cdot$mol$^{-1}\cdot$K$^{-2}$.
+Magnetic field leaves the value of N\'{e}el temperature for both URhIn$_{5}$
+and U$_{2}$RhIn$_{8}$ unaffected up to 9 T. On the other hand, T$_{\textrm{N}}$
+is increasing with applying hydrostatic pressure up to 3.2 GPa. The weak
+temperature dependence of $\chi(T)$ in all studied compounds might be
+attributed to the mainly itinerant nature of 5f electrons. The character of
+uranium 5f electron states of U$_{2}$RhIn$_{8}$ was studied by first principles
+calculations based on the density functional theory. The overall phase diagram
+of U$_{2}$RhIn$_{8}$ is discussed in the context of magnetism in the related
+URhX$_{5}$ and UX$_{3}$ (X = In, Ga) compounds.",1501.02154v1
+2016-05-08,Exchange bias-like effect in TbFeAl intermetallic induced by atomic disorder,"Exchange bias-like effect observed in the intermetallic compound TbFeAl,
+which displays a magnetic phase transition at $T^h_c \approx$ 198~K and a
+second one at $T^l_c \approx$ 154~K, is reported. {\em Jump}-like features are
+observed in the isothermal magnetization, $M (H)$, at 2~K which disappear above
+8~K. The field-cooled magnetization isotherms below 10~K show loop-shifts that
+are reminiscent of exchange bias, also supported by {\em training effect}.
+Significant coercive field, $H_c \approx$ 1.5~T at 2~K is observed in TbFeAl
+which, after an initial increase, shows subsequent decrease with temperature.
+The exchange bias field, $H_{eb}$, shows a slight increase and subsequent
+leveling off with temperature. It is argued that the inherent crystallographic
+disorder among Fe and Al and the high magnetocrystalline anisotropy related to
+Tb$^{3+}$ lead to the exchange bias effect. TbFeAl is recently reported to show
+magnetocaloric effect and the present discovery of exchange bias makes this
+compound a multifunctional one. The result obtained on TbFeAl generalizes the
+observation of exchange bias in crystallographically disordered materials and
+gives impetus for the search for materials with {\em exchange bias induced by
+atomic disorder.}",1605.02381v1
+2016-07-07,Deciphering chemical order/disorder and material properties at the single-atom level,"Correlating 3D arrangements of atoms and defects with material properties and
+functionality forms the core of several scientific disciplines. Here, we
+determined the 3D coordinates of 6,569 iron and 16,627 platinum atoms in a
+model iron-platinum nanoparticle system to correlate 3D atomic arrangements and
+chemical order/disorder with material properties at the single-atom level. We
+identified rich structural variety and chemical order/disorder including 3D
+atomic composition, grain boundaries, anti-phase boundaries, anti-site point
+defects and swap defects. We show for the first time that experimentally
+measured 3D atomic coordinates and chemical species with 22 pm precision can be
+used as direct input for first-principles calculations of material properties
+such as atomic magnetic moments and local magnetocrystalline anisotropy. This
+work not only opens the door to determining 3D atomic arrangements and chemical
+order/disorder of a wide range of nanostructured materials with high precision,
+but also will transform our understanding of structure-property relationships
+at the most fundamental level.",1607.02051v1
+2016-09-12,Spin structures of textured and isotropic Nd-Fe-B-based nanocomposites: Evidence for correlated crystallographic and spin texture,"We report the results of a comparative study of the magnetic microstructure
+of textured and isotropic
+$\mathrm{Nd}_2\mathrm{Fe}_{14}\mathrm{B}/\alpha$-$\mathrm{Fe}$ nanocomposites
+using magnetometry, transmission electron microscopy, synchrotron x-ray
+diffraction, and, in particular, magnetic small-angle neutron scattering
+(SANS). Analysis of the magnetic neutron data of the textured specimen and
+computation of the correlation function of the spin misalignment SANS cross
+section suggests the existence of inhomogeneously magnetized regions on an
+intraparticle nanometer length scale, about $40-50 \, \mathrm{nm}$ in the
+remanent state. Possible origins for this spin disorder are discussed: it may
+originate in thin grain-boundary layers (where the materials parameters are
+different than in the $\mathrm{Nd}_2\mathrm{Fe}_{14}\mathrm{B}$ grains), or it
+may reflect the presence of crystal defects (introduced via hot pressing), or
+the dispersion in the orientation distribution of the magnetocrystalline
+anisotropy axes of the $\mathrm{Nd}_2\mathrm{Fe}_{14}\mathrm{B}$ grains. X-ray
+powder diffraction data reveal a crystallographic texture in the direction
+perpendicular to the pressing direction -- a finding which might be related to
+the presence of a texture in the magnetization distribution, as inferred from
+the magnetic SANS data.",1609.03383v1
+2016-11-28,Multiscale examination of strain effects in Nd-Fe-B permanent magnets,"We have performed a combined first-principles and micromagnetic study on the
+strain effects in Nd-Fe-B magnets. First-principles calculations on Nd2Fe14B
+reveal that the magnetocrystalline anisotropy (K) is insensitive to the
+deformation along c axis and the ab in-plane shrinkage is responsible for the K
+reduction. The predicted K is more sensitive to the lattice deformation than
+what the previous phenomenological model suggests. The biaxial and triaxial
+stress states have a greater impact on K. Negative K occurs in a much wider
+strain range in the ab biaxial stress state. Micromagnetic simulations of
+Nd-Fe-B magnets using first-principles results show that a 3-4% local strain in
+a 2-nm-wide region near the interface around the grain boundaries and triple
+junctions leads to a negative local K and thus decreases the coercivity by
+~60%. The local ab biaxial stress state is more likely to induce a large loss
+of coercivity. In addition to the local stress states and strain levels
+themselves, the shape of the interfaces and the intergranular phases also makes
+a difference in determining the coercivity. Smoothing the edge and reducing the
+sharp angle of the triple regions in Nd-Fe-B magnets would be favorable for a
+coercivity enhancement.",1611.08940v2
+2017-05-12,Pseudo-Goldstone magnons in the frustrated S=3/2 Heisenberg helimagnet ZnCr2Se4 with a pyrochlore magnetic sublattice,"Low-energy spin excitations in any long-range ordered magnetic system in the
+absence of magnetocrystalline anisotropy are gapless Goldstone modes emanating
+from the ordering wave vectors. In helimagnets, these modes hybridize into the
+so-called helimagnon excitations. Here we employ neutron spectroscopy supported
+by theoretical calculations to investigate the magnetic excitation spectrum of
+the isotropic Heisenberg helimagnet ZnCr2Se4 with a cubic spinel structure, in
+which spin-3/2 magnetic Cr3+ ions are arranged in a geometrically frustrated
+pyrochlore sublattice. Apart from the conventional Goldstone mode emanating
+from the (0 0 q) ordering vector, low-energy magnetic excitations in the
+single-domain proper-screw spiral phase show soft helimagnon modes with a small
+energy gap of ~0.17 meV, emerging from two orthogonal wave vectors (q 0 0) and
+(0 q 0) where no magnetic Bragg peaks are present. We term them
+pseudo-Goldstone magnons, as they appear gapless within linear spin-wave theory
+and only acquire a finite gap due to higher-order quantum-fluctuation
+corrections. Our results are likely universal for a broad class of symmetric
+helimagnets, opening up a new way of studying weak magnon-magnon interactions
+with accessible spectroscopic methods.",1705.04642v3
+2018-02-12,Canted ferrimagnetism and giant coercivity in the non-stoichiometric double perovskite La2Ni1.19Os0.81O6,"The non-stoichiometric double perovskite oxide La2Ni1.19Os0.81O6 was
+synthesized by solid state reaction and its crystal and magnetic structures
+were investigated by powder x-ray and neutron diffraction. La2Ni1.19Os0.81O6
+crystallizes in the monoclinic double perovskite structure (general formula
+A2BB'O6) with space group P21/n, where the B site is fully occupied by Ni and
+the B' site by 19 % Ni and 81 % Os atoms. Using x-ray absorption spectroscopy
+an Os4.5+ oxidation state was established, suggesting presence of about 50 %
+paramagnetic Os5+ (5d3, S = 3/2) and 50 % non-magnetic Os4+ (5d4, Jeff = 0)
+ions at the B' sites. Magnetization and neutron diffraction measurements on
+La2Ni1.19Os0.81O6 provide evidence for a ferrimagnetic transition at 125 K. The
+analysis of the neutron data suggests a canted ferrimagnetic spin structure
+with collinear Ni2+ spin chains extending along the c axis but a non-collinear
+spin alignment within the ab plane. The magnetization curve of
+La2Ni1.19Os0.81O6 features a hysteresis with a very high coercive field, HC =
+41 kOe, at T = 5 K, which is explained in terms of large magnetocrystalline
+anisotropy due to the presence of Os ions together with atomic disorder. Our
+results are encouraging to search for rare earth free hard magnets in the class
+of double perovskite oxides.",1802.03874v1
+2018-02-22,Temperature- and field-driven spin reorientations in triple-layer ruthenate Sr$_4$Ru$_3$O$_{10}$,"Sr$_4$Ru$_3$O$_{10}$, the $n$ = 3 member of the Ruddlesden-Popper type
+ruthenate Sr$_{n+1}$Ru$_n$O$_{3n+1}$, is known to exhibit a peculiar
+metamagnetic transition in an in-plane magnetic field. However, the nature of
+both the temperature- and field-dependent phase transitions remains as a topic
+of debate. Here, we have investigated the magnetic transitions of
+Sr$_4$Ru$_3$O$_{10}$ via single-crystal neutron diffraction measurements. At
+zero field, we find that the system undergoes a ferromagnetic transition with
+both in-plane and out-of-plane magnetic components at $T_{c}$ ~ 100 K. Below
+$T^{*}$ ~ 50 K, the magnetic moments incline continuously toward the
+out-of-plane direction. At $T$ ~ 1.5 K, where the spins are nearly aligned
+along the $c$ axis, a spin reorientation occurs above a critical field $B_c$,
+giving rise to a spin component perpendicular to the plane defined by the field
+direction and the $c$ axis. We suggest that both the temperature- and
+field-driven spin reorientations are associated with a change in the
+magnetocrystalline anisotropy, which is strongly coupled to the lattice degrees
+of freedom. This study elucidates the long-standing puzzles on the zero-field
+magnetic orders of Sr$_4$Ru$_3$O$_{10}$ and provides new insights into the
+nature of the field-induced metamagnetic transition.",1802.08293v1
+2018-03-06,Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe$_3$GeTe$_2$,"Material research has been a major driving force in the development of modern
+nano-electronic devices. In particular, research in magnetic thin films has
+revolutionized the development of spintronic devices; identifying new magnetic
+materials is key to better device performance and new device paradigm. The
+advent of two-dimensional van der Waals crystals creates new possibilities.
+This family of materials retain their chemical stability and structural
+integrity down to monolayers and, being atomically thin, are readily tuned by
+various kinds of gate modulation. Recent experiments have demonstrated that it
+is possible to obtain two-dimensional ferromagnetic order in insulating
+Cr$_2$Ge$_2$Te$_6$ and CrI$_3$ at low temperatures. Here, we developed a new
+device fabrication technique, and successfully isolated monolayers from layered
+metallic magnet Fe$_3$GeTe$_2$ for magnetotransport study. We found that the
+itinerant ferromagnetism persists in Fe$_3$GeTe$_2$ down to monolayer with an
+out-of-plane magnetocrystalline anisotropy. The ferromagnetic transition
+temperature, $T_c$, is suppressed in pristine Fe$_3$GeTe$_2$ thin flakes. An
+ionic gate, however, dramatically raises the $T_c$ up to room temperature,
+significantly higher than the bulk $T_c$ of 205 Kelvin. The gate-tunable
+room-temperature ferromagnetism in two-dimensional Fe$_3$GeTe$_2$ opens up
+opportunities for potential voltage-controlled magnetoelectronics based on
+atomically thin van der Waals crystals.",1803.02038v1
+2018-03-08,Direct imaging of antiferromagnetic domains in Mn$_2$Au manipulated by high magnetic fields,"In the field of antiferromagnetic (AFM) spintronics, information about the
+N\'eel vector, AFM domain sizes, and spin-flop fields is a prerequisite for
+device applications but is not available easily. We have investigated AFM
+domains and spin-flop induced changes of domain patterns in Mn2Au(001)
+epitaxial thin films by X-ray magnetic linear dichroism photoemission electron
+microscopy (XMLD-PEEM) using magnetic fields up to 70 T. As-prepared Mn$_2$Au
+films exhibit AFM domains with an average size $\sim$ 1 $\mu$m. Application of
+a 30T field, exceeding the spin-flop field, along a magnetocrystalline easy
+axis, dramatically increases the AFM domain size with N\'eel vectors
+perpendicular to the applied field direction. The width of N\'eel type domain
+walls (DW) is below the spatial resolution of the PEEM and therefore can only
+be estimated from an analysis of the DW profile to be smaller than 80 nm.
+Furthermore, using the values for the DW width and the spin-flop field, we
+evaluate an in-plane anisotropy constant ranging between 1 and 17 $\mu$eV/f.u.",1803.03022v1
+2018-04-10,Synthesis and magnetic properties of spin-$\frac{3}{2}$ $γ$-phase of SrCo$_{2}$(PO$_{4}$)$_{2}$ antiferromagnet,"We report on the synthesis of a new $\gamma$-phase of the spin
+$S$~=~$\frac{3}{2}$ compound SrCo$_2$(PO$_4$)$_2$ together with a detailed
+structural, magnetic and thermodynamic properties. The $\gamma$-phase of
+SrCo$_2$(PO$_4$)$_2$ crystallizes in a triclinic crystal structure with the
+space group $P\bar{1}$. Susceptibility and specific heat measurements reveal
+that SrCo$_2$(PO$_4$)$_2$ orders antiferromagnetically below $T_{\rm N}\simeq
+8.5$\,K and the nature of ordering is three dimensional (3D). The magnetic
+isotherm at temperatures below $T_{\rm N}$ shows a field-induced spin-flop
+transition, related to the magnetocrystalline anisotropy, at an applied field
+of $\sim$~4.5~Tesla. Remarkably, heat capacity shows magnetic-field-induced
+transitions at $T_{\rm N1}$ = 3.6 K and $T_{\rm N2}$ = 7.4 K. The magnetic long
+range ordering (LRO) is also confirmed in both the Knight shift and
+spin-lattice relaxation rate ($1/T_{1}$) of the $^{31}$P-NMR measurements.
+However, below the LRO we have not detected any NMR signal due to faster
+relaxation. We have detected two structurally different phosphorous sites in
+$\gamma$-phase of SrCo$_{2}$(PO$_{4}$)$_{2}$ and they shift differently with
+temperature.",1804.03464v2
+2018-04-24,Antiferromagnetism and phase transitions in non-centrosymmetric UIrSi$_3$,"Magnetization and specific heat measurements on a UIrSi3 single crystal
+reveal Ising-like antiferromagnetism below T$_N$ = 41.7 K with easy
+magnetization direction along the c-axis of tetragonal structure. The
+antiferromagentic ordering is suppressed by magnetic fields > H$_c$
+({\mu}$_0$H$_c$ = 7.3 T at 2 K) applied along the c-axis. The first-order
+metamagnetic transition at H$_c$ exhibits asymmetric hysteresis reflecting a
+slow reentry of the complex ground-state antiferromagnetic structure with
+decreasing field. The hysteresis narrows with increasing temperature and
+vanishes at 28 K. A second-order metamagnetic transition is observed at higher
+temperatures. The point of change of the order of transition in the established
+H-T magnetic phase diagram is considered as the tricritical point (at T$_{tc}$
+= 28 K and {\mu}$_0$H$_{tc}$ = 5.8 T). The modified-Curie-Weiss-law fits of
+temperature dependence of the a- and c-axis susceptibility provide opposite
+signs of Weiss temperatures, {\Theta}$_p^a$ ~ -51 K and {\Theta}$_p^c$ ~ +38 K,
+respectively. This result and the small value of {\mu}$_0$H$_c$ contrasting to
+the high T$_N$ indicate competing ferromagnetic and antiferromagnetic
+interactions responsible for the complex antiferromagnetic ground state. The
+simultaneous electronic-structure calculations focused on the total energy of
+ferromagentic and various antiferromagnetic states, the U magnetic moment and
+magnetocrystalline anisotropy provide results consistent with experimental
+findings and the suggested physical picture of the system.",1804.08832v1
+2018-09-13,Single-layer antiferromagnetic semiconductor CoS2 with the pentagonal structure,"Structure-property relationships have always been guiding principles in
+discovering new materials. Here we explore the relationships to discover novel
+two-dimensional (2D) materials with the goal of identifying 2D magnetic
+semiconductors for spintronics applications. In particular, we report a density
+functional theory + $U$ study of single-layer antiferromagnetic (AFM)
+semiconductor CoS$_2$ with the pentagonal structure forming the so-called Cairo
+Tessellation. We find that this single-layer magnet exhibits an indirect
+bandgap of 1.06 eV with light electron and hole effective masses of 0.03 and
+0.10 $m_0$, respectively, which may lead to high carrier mobilities. The hybrid
+density functional theory calculations correct the bandgap to 2.24 eV. We also
+compute the magnetocrystalline anisotropy energy (MAE), showing that the easy
+axis of the AFM ordering is out of plane with a sizable MAE of 153 $\mu$eV per
+Co ion. We further calculate the magnon frequencies at different spin-spiral
+vectors, based on which we estimate the N$\acute{e}$el temperatures to be 20.4
+and 13.3 K using the mean field and random phase approximations, respectively.
+We then apply biaxial strains to tune the bandgap of single-layer pentagonal
+CoS$_2$. We find that the energy difference between the ferromagnetic and AFM
+structures strongly depends on the biaxial strain, but the ground state remains
+the AFM ordering. Although the low critical temperature prohibits the magnetic
+applications of single-layer pentagonal CoS$_2$ at room temperature, the
+excellent electrical properties may find this novel single-layer semiconductor
+applications in optoelectronic nanodevices.",1809.05055v1
+2018-10-02,Building traps for skyrmions by the incorporation of magnetic defects into nanomagnets: pinning and scattering traps by magnetic properties engineering,"In this work we have used micromagnetic simulations to report four ways to
+build traps for magnetic skyrmions. Magnetic defects have been modeled as local
+variations in the material parameters, such as the exchange stiffness,
+saturation magnetization, magnetocrystalline anisotropy and
+Dzyaloshinskii-Moriya constant. We observe both pinning (potential well) and
+scattering (potential barrier) traps when tuning either a local increase or a
+local reduction for each one of these magnetic properties. It is found that the
+skyrmion-defect aspect ratio is a crucial parameter to build traps for
+skyrmions. In particular, the efficiency of the trap is compromised if the
+defect size is smaller than the skyrmion size, because they interact weakly. On
+the other hand, if the defect size is larger than the skyrmion diameter, the
+skyrmion-defect interaction becomes evident. Thus, the strength of the
+skyrmion-defect interaction can be tuned by the modification of the magnetic
+properties within a region with suitable size. Furthermore, the basic physics
+behind the mechanisms for pinning and for scattering is discussed. In
+particular, we discover that skyrmions move towards the magnetic region which
+tends to maximize its diameter; it enables the magnetic system to minimize its
+energy. Thus, we are able to explain why skyrmions are either attracted or
+repelled by a region with modified magnetic properties. Results here presented
+are of utmost significance for the development and realization of future
+spintronic devices, in which skyrmions will work as information carriers.",1810.03754v2
+2018-11-08,Single-Layer Ferromagnetic and Piezoelectric CoAsS with Pentagonal Structure,"Single-layer pentagonal materials are an emerging family of two-dimensional
+(2D) materials that could exhibit novel properties due to the building blocks
+being pentagons instead of hexagons as in numerous 2D materials. Based on our
+recently predicted single-layer pentagonal CoS$_2$ that is an antiferromagnetic
+(AFM) semiconductor, we replace two S atoms by As atoms in a unit cell to form
+single-layer pentagonal CoAsS. The resulting single-layer material is
+dynamically stable ac-cording to the phonon calculations. We find two drastic
+changes in the properties of single-layer pentagonal CoAsS in comparison with
+those of CoS$_2$. First, we find a magnetic transition from the AFM to FM
+ordering. We understand that the transition is caused by the lower
+electronegativity of As atoms, leading to the weakened bridging roles on the
+superexchange interactions be-tween Co ions. Single-layer pentagonal CoAsS also
+shows significantly stronger magnetocrystalline anisotropy energy due to
+stronger spin-orbit coupling. We additionally perform Monte Carlo simulations
+to calculate the Curie temperature of single-layer pentagonal CoAsS and the
+predicted Curie temperature is 103 K. Second, we find that single-layer
+pentagonal CoAsS exhibits piezoelectricity, which is absent in single-layer
+pentagonal CoS$_2$ due to its center of symmetry. The computed piezoelectric
+coefficients are also sizable. The rare coexistence of FM ordering and
+piezoelectric properties makes single-layer pentagonal CoAsS a promising
+multifunctional 2D material.",1811.03469v1
+2019-01-07,Field-induced phases in a heavy-fermion U(Ru$_{0.92}$Rh$_{0.08}$)$_{2}$Si$_{2}$ single crystal,"We report the high-field induced magnetic phases and phase diagram of a high
+quality \urxrs~single crystal prepared using a modified Czochralski method. Our
+study, that combines high-field magnetization and electrical resistivity
+measurements, shows for fields applied along the $c$-axis direction three
+field-induced magnetic phase transitions at $\mu_{0} H_{c1}$ = 21.60 T,
+$\mu_{0} H_{c2}$ = 37.90 T and $\mu_{0} H_{c3}$ = 38.25 T, respectively. In
+agreement with a microscopic up-up-down arrangement of the U magnetic moments
+the phase above $H_{c1}$ has a magnetization of about one third of the
+saturated value. In contrast the phase between $H_{c2}$ and $H_{c3}$ has a
+magnetization that is a factor of two lower than above the $H_{c3}$, where a
+polarized Fermi-liquid state with a saturated moment $M_{s}$ $\approx$ 2.1
+$\mu_{B}$/U is realized. Most of the respective transitions are reflected in
+the electrical resistivity as sudden drastic changes. Most notably, the phase
+between $H_{c1}$ and $H_{c2}$ exhibits substantially larger values. As the
+temperature increases, transitions smear out and disappear above $\approx$ 15
+K. However, a substantial magnetoresistance is observed even at temperatures as
+high as 80 K. Due to a strong uniaxial magnetocrystalline anisotropy a very
+small field effect is observed for fields apllied perpendicular to the $c$-axis
+direction.",1901.01750v1
+2019-03-27,Structural and magnetic properties of GdCo$_{5-x}$Ni$_x$,"GdCo$_5$ may be considered as two sublattices - one of Gd and one of Co -
+whose magnetizations are in antiparallel alignment, forming a ferrimagnet.
+Substitution of nickel in the cobalt sublattice of GdCo$_5$ has been
+investigated to gain insight into how the magnetic properties of this prototype
+rare-earth/transition-metal magnet are affected by changes in the transition
+metal sublattice. Polycrystalline samples of GdCo$_{5-x}$Ni$_x$ for 0 $ \leq x
+\leq $ 5 were synthesized by arc melting. Structural characterization was
+carried out by powder x-ray diffraction and optical and scanning electron
+microscope imaging of metallographic slides, the latter revealing a low
+concentration of Gd$_2$(Co, Ni)$_7$ lamellae for $x \leq 2.5$. Compensation -
+i.e. the cancellation of the opposing Gd and transition metal moments is
+observed for $1 \leq x \leq 3$ at a temperature which increases with Ni
+content; for larger $x$, no compensation is observed below 360 K. A peak in the
+coercivity is seen at $x \approx 1$ at 10K coinciding with a minimum in the
+saturation magnetization. Density-functional theory calculations within the
+disordered local moment picture reproduce the dependence of the magnetization
+on Ni content and temperature. The calculations also show a peak in the
+magnetocrystalline anisotropy at similar Ni concentrations to the
+experimentally observed coercivity maximum.",1903.11442v1
+2020-02-28,Traps for pinning and scattering of antiferromagnetic skyrmions via magnetic properties engineering,"Micromagnetic simulations have been performed to investigate the
+controllability of the skyrmion position in antiferromagnetic nanotracks with
+their magnetic properties modified spatially. In this study we have modeled
+magnetic defects as local variations on the material parameters, such as the
+exchange stiffness, saturation magnetization, perpendicular magnetocrystalline
+anisotropy and Dzyaloshinskii-Moriya constant. Thus, we have observed not only
+pinning (potential well) but also scattering (potential barrier) of
+antiferromagnetic skyrmions, when adjusting either a local increase or a local
+reduction for each material parameter. In order to control of the skyrmion
+motion it is very important to impose certain positions along the nanotrack
+where the skyrmion can stop. Magnetic defects incorporated intentionally in
+antiferromagnetic racetracks can be useful for such purpose. In order to
+provide guidelines for experimental studies, we vary both material parameters
+and size of the modified region. The found results show that the efficiency of
+skyrmion trap depends on a suitable combination of magnetic defect parameters.
+Furthermore, we discuss the reason why skyrmions are either attracted or
+repelled by a region magnetically modified.",2003.00907v2
+2020-04-17,Magnetic correlations in subsystems of the misfit [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$] cobaltate,"[Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$], a two dimensional misfit metallic
+compound, is famous for its rich phases accessed by temperature, $i.e.$ high
+temperature spin-state transition, metal-insulator transition (MIT) at
+intermediate temperature ($\sim$ 100 K) and low temperature spin density wave
+(SDW). It enters into SDW phase below T$_{MIT}$ which becomes long range at 27
+K. Information on the independent role of misfit layers (rocksalt/Ca$_2$CoO$_3$
+\& triangular/CoO$_2$) in these phases is scarce. By combining a set of
+complementary macroscopic (DC magnetization and resistivity) and microscopic
+(neutron diffraction and X-ray absorption fine structure spectroscopy)
+measurements on pure (CCO) and Tb substituted in the rocksalt layer of CCO
+(CCO1), magnetic correlations in both subsystems of this misfit compound are
+unraveled. CCO is found to exhibit glassiness, as well as exchange bias (EB)
+effects, while CCO1 does not exhibit glassiness, albeit it shows weaker EB
+effect. By combining local structure investigations from extended X-ray
+absorption fine structure (EXAFS) spectroscopy and neutron diffraction results
+on CCO, we confirm that the SDW arises in the CoO$_2$ layer. Our results show
+that the magnetocrystalline anisotropy associated with the rocksalt layer acts
+as a source of pinning, which is responsible for EB effect. Ferromagnetic
+clusters in the Ca$_2$CoO$_3$ affects SDW in CoO$_2$ and ultimately glassiness
+arises.",2004.08319v2
+2020-04-24,Observation of magnetic domain and bubble structures in magnetoelectric Sr$_3$Co$_2$Fe$_{24}$O$_{41}$,"The magnetic domain and bubble structures in the Z-type hexaferrite
+Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ were investigated using Lorentz microscopy. This
+hexaferrite exhibits a room-temperature magnetoelectric effect that is
+attributed to its transverse conical spin structure (TC phase). Upon heating,
+the TC phase transforms into a ferrimagnetic phase with magnetic moments in the
+hexagonal $ab$ plane between 410 and 480 K (FM2 phase) and into another
+ferrimagnetic phase with moments parallel to the $c$ axis between 490 and 680 K
+(FM1 phase). Accordingly, in this study, the magnetic domain structures in
+Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ were observed to change dramatically with
+temperature. In the TC phase, irregular fine magnetic domains were observed
+after cooling the specimen from the FM2 to TC phase. In the FM1 phase, striped
+magnetic domain walls with pairs of bright and dark contrast were formed
+parallel to the $c$ axis. Upon applying an external magnetic field, the striped
+magnetic domain walls transformed into magnetic bubbles. The topology of the
+magnetic bubbles was dependent on the angle between the external magnetic field
+($H$) direction and the easy $c$ axis. Namely, magnetic bubbles with the
+topological number $N$ = 1 (type I) were created for $H//c$, whereas magnetic
+bubbles with $N$ = 0 (type II) were created when the magnetic field was tilted
+from the c axis by 5{\deg}. We attribute the high magnetocrystalline anisotropy
+of Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ to the emergence of magnetic bubbles in the
+FM1 phase.",2004.11591v1
+2020-08-27,"Different universality classes of isostructural U$TX$ compounds ($T$ = Rh, Co, Co$_{0.98}$Ru$_{0.02}$; $X$ = Ga, Al)","Magnetization isotherms of the 5f-electron ferromagnets URhGa, UCoGa and
+UCo0.98Ru0.02Al were measured at temperatures in the vicinity of their Curie
+temperature in order to investigate the critical behavior near the
+ferromagnetic phase transition. These compounds adopt the layered hexagonal
+ZrNiAl-type structure and exhibit huge uniaxial magnetocrystalline anisotropy.
+The critical \b{eta}, {\gamma} and {\delta} exponents were determined by
+analyzing Arrott-Noakes plots, Kouvel-Fisher plots, critical isotherms, scaling
+theory and Widom scaling relations. The values obtained for URhGa and UCoGa can
+be explained by the results of the renormalization group theory for a 2D Ising
+system with long-range interactions similar to URhAl reported by other
+investigators. On the other hand, the critical exponents determined for
+UCo0.98Ru0.02Al are characteristic of a 3D Ising ferromagnet with short-range
+interactions suggested in previous studies also for the itinerant 5f-electron
+paramagnet UCoAl situated near a ferromagnetic transition. The change from the
+2D to the 3D Ising system is related to the gradual delocalization of 5f
+electrons in the series of the URhGa, URhAl, UCoGa to UCo0.98Ru0.02Al and UCoAl
+compounds and appears close to the strongly itinerant nonmagnetic limit. This
+indicates possible new phenomena that may be induced by the change of
+dimensionality in the vicinity of the quantum critical point.",2008.12061v1
+2020-09-14,Multifunctional Antiperovskites driven by Strong Magnetostructural Coupling,"Based on density functional theory calculations, we elucidated the origin of
+multifunctional properties for cubic antiperovskites with noncollinear magnetic
+ground states, which can be attributed to strong isotropic and anisotropic
+magnetostructural coupling. 16 out of 54 stable magnetic antiperovskites
+M$_3$XZ (M = Cr, Mn, Fe, Co, and Ni; X = selected elements from Li to Bi except
+for noble gases and 4f rare-earth metals; and Z = C and N) are found to exhibit
+the $\Gamma_{4g}$/$\Gamma_{5g}$ (i.e., characterized by irreducible
+representations) antiferromagnetic magnetic configurations driven by frustrated
+exchange coupling and strong magnetocrystalline anisotropy. Using the magnetic
+deformation as an effective proxy, the isotropic magnetostructural coupling is
+characterized, and it is observed that the paramagnetic state is critical to
+understand the experimentally observed negative thermal expansion and to
+predict the magnetocaloric performance. Moreover, the piezomagnetic and
+piezospintronic effects induced by biaxial strain are investigated. It is
+revealed that there is not a strong correlation between the induced
+magnetization and anomalous Hall conductivities by the imposed strain.
+Interestingly, the anomalous Hall/Nernst conductivities can be significantly
+tailored by the applied strain due to the fine-tuning of the Weyl points
+energies, leading to promising spintronic applications.",2009.06440v1
+2020-11-01,"Tunable magneto-optical effect, anomalous Hall effect and anomalous Nernst effect in two-dimensional room-temperature ferromagnet $1T$-CrTe$_2$","Utilizing the first-principles density functional theory calculations
+together with group theory analyses, we systematically investigate the spin
+order-dependent magneto-optical effect (MOE), anomalous Hall effect (AHE), and
+anomalous Nernst effect (ANE) in a recently discovered two-dimensional
+room-temperature ferromagnet $1T$-CrTe$_2$. We find that the spin prefers an
+in-plane direction by the magnetocrystalline anisotropy energy calculations.
+The MOE, AHE, and ANE display a period of $2\pi/3$ when the spin rotates within
+the atomic plane, and they are forbidden if there exists a mirror plane
+perpendicular to the spin direction. By reorienting the spin from in-plane to
+out-of-plane direction, the MOE, AHE, and ANE are enhanced by around one order
+of magnitude. Moreover, we establish the layer-dependent magnetic properties
+for multilayer $1T$-CrTe$_2$ and predict antiferromagnetism and ferromagnetism
+for bilayer and trilayer $1T$-CrTe$_2$, respectively. The MOE, AHE, and ANE are
+prohibited in antiferromagnetic bilayer $1T$-CrTe$_2$ due to the existence of
+the spacetime inversion symmetry, whereas all of them are activated in
+ferromagnetic trilayer $1T$-CrTe$_2$ and the MOE is significantly enhanced
+compared to monolayer $1T$-CrTe$_2$. Our results show that the magneto-optical
+and anomalous transports proprieties of $1T$-CrTe$_2$ can be effectively
+modulated by altering spin direction and layer number.",2011.00394v1
+2021-02-10,Magneto-electric Tuning of Pinning-Type Permanent Magnets through Atomic-Scale Engineering of Grain Boundaries,"Pinning-type magnets maintaining high coercivity, i.e. the ability to sustain
+magnetization, at high temperature are at the core of thriving clean-energy
+technologies. Among these, Sm2Co17-based magnets are excellent candidates owing
+to their high-temperature stability. However, despite decades of efforts to
+optimize the intragranular microstructure, the coercivity currently only
+reaches 20~30% of the theoretical limits. Here, the roles of the grain-interior
+nanostructure and the grain boundaries in controlling coercivity are
+disentangled by an emerging magneto-electric approach. Through hydrogen
+charging/discharging by applying voltages of only ~ 1 V, the coercivity is
+reversibly tuned by an unprecedented value of ~ 1.3 T. In situ
+magneto-structural measurements and atomic-scale tracking of hydrogen atoms
+reveal that the segregation of hydrogen atoms at the grain boundaries, rather
+than the change of the crystal structure, dominates the reversible and
+substantial change of coercivity. Hydrogen lowers the local magnetocrystalline
+anisotropy and facilitates the magnetization reversal starting from the grain
+boundaries. Our study reveals the previously neglected critical role of grain
+boundaries in the conventional magnetisation-switching paradigm, suggesting a
+critical reconsideration of strategies to overcome the coercivity limits in
+permanent magnets, via for instance atomic-scale grain boundary engineering.",2102.05315v1
+2021-03-05,Ferromagnetic Composite Self-Arrangement in Iron-Implanted Epitaxial Palladium Thin Films,"We report on the formation of the dilute $Pd_{1-x}Fe_x$ compositions with
+tunable magnetic properties under an ion-beam implantation of epitaxial Pd thin
+films. Binary $Pd_{1-x}Fe_x$ alloys with a mean iron content $x$ of $0.025$,
+$0.035$ or $0.075$ were obtained by the implantation of $40 keV$ $Fe^+$ ions
+into the palladium films on MgO (001) substrate to the doses of
+$0.5\cdot10^{16}, 1.0\cdot10^{16}$ and $3.0\cdot10^{16}$ $ions/cm^2$,
+respectively. Structural and magnetic studies have shown that iron atoms occupy
+regular fcc-lattice Pd-sites without the formation of any secondary
+crystallographic phase. All the iron implanted Pd films reveal ferromagnetism
+at low temperatures (below $200 K$) with both the Curie temperature and
+saturation magnetization determined by the implanted iron dose. In contrast to
+the magnetic properties of the molecular beam epitaxy grown $Pd_{1-x}Fe_x$
+alloy films with the similar iron contents, the Fe-implanted Pd films possess
+weaker in-plane magnetocrystalline anisotropy, and, accordingly, a lower
+coercivity. The observed multiple ferromagnetic resonances in the implanted
+$Pd_{1-x}Fe_x$ films indicate a formation of a magnetically inhomogeneous state
+due to spinodal decomposition into regions, presumably layers, with identical
+crystal symmetry but different iron contents. The multiphase magnetic structure
+is robust with respect to the vacuum annealing at $770 K$, though develops
+towards well-defined local $Pd-Fe$ compositions.",2103.03562v1
+2021-03-22,Field-induced reorientation of helimagnetic order in Cu$_2$OSeO$_3$ probed by magnetic force microscopy,"Cu$_2$OSeO$_3$ is an insulating skyrmion-host material with a magnetoelectric
+coupling giving rise to an electric polarization with a characteristic
+dependence on the magnetic field $\vec H$. We report magnetic force microscopy
+imaging of the helical real-space spin structure on the surface of a bulk
+single crystal of Cu$_2$OSeO$_3$. In the presence of a magnetic field, the
+helimagnetic order in general reorients and acquires a homogeneous component of
+the magnetization, resulting in a conical arrangement at larger fields. We
+investigate this reorientation process at a temperature of 10~K for fields
+close to the crystallographic $\langle 110\rangle$ direction that involves a
+phase transition at $H_{c1}$. Experimental evidence is presented for the
+formation of magnetic domains in real space as well as for the microscopic
+origin of relaxation events that accompany the reorientation process. In
+addition, the electric polarization is measured by means of Kelvin-probe force
+microscopy. We show that the characteristic field dependency of the electric
+polarization originates in this helimagnetic reorientation process. Our
+experimental results are well described by an effective Landau theory
+previously invoked for MnSi, that captures the competition between
+magnetocrystalline anisotropies and Zeeman energy.",2103.11953v1
+2021-04-27,Observation of a phase transition within the domain walls of ferromagnetic Co3Sn2S2,"The ferromagnetic phase of Co$_3$Sn$_2$S$_2$ is widely considered to be a
+topological Weyl semimetal, with evidence for momentum-space monopoles of Berry
+curvature from transport and spectroscopic probes. As the bandstructure is
+highly sensitive to the magnetic order, attention has focused on anomalies in
+magnetization, susceptibility and transport measurements that are seen well
+below the Curie temperature, leading to speculation that a ""hidden"" phase
+coexists with ferromagnetism. Here we report spatially-resolved measurements by
+Kerr effect microscopy that identify this phase. We find that the anomalies
+coincide with a deep minimum in domain wall (DW) mobility, indicating a
+crossover between two regimes of DW propagation. We demonstrate that this
+crossover is a manifestation of a 2D phase transition that occurs within the
+DW, in which the magnetization texture changes from continuous rotation to
+unidirectional variation. We propose that the existence of this 2D transition
+deep within the ferromagnetic state of the bulk is a consequence of a giant
+quality factor for magnetocrystalline anisotropy unique to this compound. This
+work broadens the horizon of the conventional binary classification of DWs into
+Bloch and N\'eel walls, and suggests new strategies for manipulation of domain
+walls and their role in electron and spin transport.",2104.13381v2
+2021-06-03,Macrospin model of an assembly of magnetically coupled core-shell nanoparticles,"Highly sophisticated synthesis methods and experimental techniques allow for
+precise measurements of magnetic properties of nanoparticles that can be
+reliably reproduced using theoretical models. Here, we investigate the magnetic
+properties of ferrite nanoparticles by using theoretical techniques based on
+Monte Carlo methods. We introduce three stages of sophistication in the
+macromagnetic model. First, by using tailor-made hamiltonians we study single
+nanoparticles. In a second stage, the internal structure of the nanoparticle is
+taken into consideration by defining an internal (core) and external (shell)
+region, respectively. In the last stage, an assembly of core/shell NPs are
+considered. All internal magnetic couplings such as inter and intra-atomic
+exchange interactions or magnetocrystalline anisotropies have been estimated.
+Moreover, the hysteresis loops of the aforementioned three cases have been
+calculated and compared with recent experimental measurements. In the case of
+the assembly of nanoparticles, the hysteresis loops together with the
+zero-field cooling and field cooling curves are shown to be in a very good
+agreement with the experimental data. The current model provides an important
+tool to understand the internal structure of the nanoparticles together with
+the complex internal spin interactions of the core-shell ferrite nanoparticles.",2106.01844v1
+2021-06-07,MAELAS 2.0: A new version of a computer program for the calculation of magneto-elastic properties,"MAELAS is a computer program for the calculation of magnetocrystalline
+anisotropy energy, anisotropic magnetostrictive coefficients and magnetoelastic
+constants in an automated way. The method originally implemented in version 1.0
+of MAELAS was based on the length optimization of the unit cell, proposed by Wu
+and Freeman, to calculate the anisotropic magnetostrictive coefficients. We
+present here a revised and updated version (v2.0) of MAELAS, where we added a
+new methodology to compute anisotropic magnetoelastic constants from a linear
+fitting of the energy versus applied strain. We analyze and compare the
+accuracy of both methods showing that the new approach is more reliable and
+robust than the one implemented in version 1.0, especially for non-cubic
+crystal symmetries. This analysis also help us to find that the accuracy of the
+method implemented in version 1.0 could be improved by using deformation
+gradients derived from the equilibrium magnetoelastic strain tensor, as well as
+potential future alternative methods like the strain optimization method.
+Additionally, we clarify the role of the demagnetized state in the fractional
+change in length, and derive the expression for saturation magnetostriction for
+polycrystals with trigonal, tetragonal and orthorhombic crystal symmetry. In
+this new version, we also fix some issues related to trigonal crystal symmetry
+found in version 1.0.",2106.03624v3
+2021-06-16,Magnetic and geometrical control of spin textures in the itinerant kagome magnet Fe$_3$Sn$_2$,"Magnetic materials with competing magnetocrystalline anisotropy and dipolar
+energies can develop a wide range of domain patterns, including classical
+stripe domains, domain branching, as well as topologically trivial and
+non-trivial (skyrmionic) bubbles. We image the magnetic domain pattern of
+Fe$_3$Sn$_2$ by magnetic force microscopy (MFM) and study its evolution due to
+geometric confinement, magnetic fields, and their combination. In Fe$_3$Sn$_2$
+lamellae thinner than 3 $\mu$m, we observe stripe domains whose size scales
+with the square root of the lamella thickness, exhibiting classical Kittel
+scaling. Magnetic fields turn these stripes into a highly disordered bubble
+lattice, where the bubble size also obeys Kittel scaling. Complementary
+micromagnetic simulations quantitatively capture the magnetic field and
+geometry dependence of the magnetic patterns, reveal strong reconstructions of
+the patterns between the surface and the core of the lamellae, and identify the
+observed bubbles as skyrmionic bubbles. Our results imply that geometrical
+confinement together with competing magnetic interactions can provide a path to
+fine-tune and stabilize different types of topologically trivial and
+non-trivial spin structures in centrosymmetric magnets.",2106.08791v1
+2021-07-14,Designing light-element materials with large effective spin-orbit coupling,"Spin-orbit coupling (SOC), the core of numerous condensed-matter phenomena
+such as nontrivial band gap, magnetocrystalline anisotropy, etc, is generally
+considered to be appreciable only in heavy elements, detrimental to the
+synthetization and application of functional materials. Therefore, amplifying
+the SOC effect in light elements is of great importance. Here, focusing on 3d
+and 4d systems, we demonstrate that the interplay between crystal symmetry and
+electron correlation can dramatically enhance the SOC effect in certain
+partially occupied orbital multiplets, through the self-consistently reinforced
+orbital polarization as a pivot. We then provide design principles and
+comprehensive databases, in which we list all the Wyckoff positions and site
+symmetries, in all two-dimensional (2D) and three-dimensional crystals that
+potentially have such enhanced SOC effect. As an important demonstration, we
+predict nine material candidates from our selected 2D material pool as
+high-temperature quantum anomalous Hall insulators with large nontrivial band
+gaps of hundreds of meV. Our work provides an efficient and straightforward way
+to predict promising SOC-active materials, releasing the burden of requiring
+heavy elements for next-generation spin-orbitronic materials and devices.",2107.06691v2
+2021-07-28,Effect of transition metal doping on magnetic hardness of CeFe$_{12}$-based compounds,"In this work, compositions of CeFe11X and CeFe10X2 with all 3d, 4d, and 5d
+transition metal substitutions are considered. Since many previous studies have
+focused on the CeFe11Ti compound, this particular compound became the starting
+point of our considerations and we gave it special attention. We first
+determined the optimal symmetry of the simplest CeFe11Ti structure model. We
+then observed that the calculated magnetocrystalline anisotropy energy (MAE)
+correlates with the magnetic moment, which in turn strongly depends on the
+choice of the exchange-correlation potential. MAE, magnetic moments, and
+magnetic hardness were determined for all compositions considered. Moreover,
+the calculated dependence of the MAE on the spin magnetic moment allowed us to
+predict the upper limits of the MAE. We also showed that it does not depend on
+the choice of the exchange-correlation potential form. The economically
+justifiable compositions with the highest magnetic hardness values are CeFe11W,
+CeFe10W2, CeFe11Mn, CeFe10Mn2, CeFe11Mo, CeFe10Mo2, and CeFe10Nb2. However,
+calculations suggest that, like CeFe12, these compounds are not chemically
+stable and could require additional treatments to stabilize the composition.
+Further alloying of the selected compositions with elements embedded in
+interstitial positions confirms the positive effect of such dopants on hard
+magnetic properties. Subsequent calculations performed for comparison for
+selected isostructural La-based compounds lead to similar MAE results as for
+Ce-based compounds, suggesting a secondary effect of 4f electrons. Calculations
+were performed using the full-potential local-orbital electronic structure code
+FPLO18, whose unique fully relativistic implementation of the fixed spin moment
+method allowed us to calculate the MAE dependence of the magnetic moment.",2107.13352v3
+2021-08-03,Tuning exchange interactions in antiferromagnetic Fe/W(001) by 4d transition-metal overlayers,"We use first-principles calculations based on density functional theory to
+study how the magnetic properties of an Fe monolayer on a W(001) surface --
+exhibiting a $c(2 \times 2)$ antiferromagnetic ground state -- can be modified
+by an additional 4d transition-metal overlayer. To obtain an overview of how
+the 4d-band filling influences the exchange interactions in the Fe layer we
+have calculated the energy dispersion of spin spirals for 4d/Fe/2W unsupported
+quadlayers, in which the W(001)substrate is represented by only two atomic
+layers. Hybridization with the overlayer leads to a reduced ferromagnetic
+nearest-neighbor exchange interaction and the next-nearest neighbor exchange
+gains in strength. Surprisingly, we find that the $c(2 \times 2)$
+antiferromagnetic state is unfavorable for all systems with a 4d overlayer. For
+4d overlayers from the beginning (Nb) or end (Pd) of the series we find a
+ferromagnetic ground state. As one moves to the center of the series there is a
+transition via a spin spiral (Mo, Rh) to a $p (2 \times 1)$ antiferromagnetic
+ground state (Tc, Ru). We have studied the Mo, Ru, and Pd overlayer on
+Fe/W(001) representing the surface by a sufficiently large number of W layers
+to obtain bulk like properties in its center. The energy dispersion of spin
+spirals show qualitatively the same results as those from the 4\textit{d}/Fe/2W
+quadlayers. The Dzyaloshinskii-Moriya interaction calculated upon including
+spin-orbit coupling shows significant strength and considerable frustration
+effects. The calculated magnetocrystalline anisotropy energy is large as well.
+All 4d/Fe/W(001) films are potential candidates for complex non-collinear spin
+structures.",2108.01359v1
+2021-08-18,Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators,"We investigate the effect of magnon-magnon interactions on the dispersion and
+polarization of magnons in collinear antiferromagnetic (AF) insulators at
+finite temperatures. In two-sublattice AF systems with either uniaxial or
+biaxial magnetocrystalline anisotropies, we implement a self-consistent
+Hartree-Fock mean-field approximation to explore the nonlinear thermal
+interactions. The resulting nonlinear magnon interactions separate into
+two-magnon intra- and interband scattering processes. Furthermore, we compute
+the temperature dependence of the magnon bandgap and AF resonance modes due to
+nonlinear magnon interactions for square and hexagonal lattices. In addition,
+we study the effect of magnon interactions on the polarization of magnon modes.
+We find that although the noninteracting eigenmodes in the uniaxial case are
+circularly polarized, but in the presence of nonlinear thermal interactions the
+local U(1) symmetry of the Hamiltonian is broken. The attractive nonlinear
+interactions squeeze the low-energy magnon modes and make them elliptical. In
+the biaxial case, on the other hand, the bare eigenmodes of low energy magnons
+are elliptically polarized but thermal nonlinear interactions squeeze them
+further. Direct measurements of the predicted temperature-dependent AF
+resonance modes and their polarization can be used as a tool to probe the
+nonlinear interactions. Our findings establish a framework for exploring the
+effect of thermal magnon interactions in technologically important magnetic
+systems, such as magnetic stability of recently discovered two-dimensional
+magnetic materials, coherent transport of magnons, Bose-Einstein condensation
+of magnons, and magnonic topological insulators.",2108.08374v4
+2021-10-25,Persistent large anisotropic magnetoresistance and insulator to metal transition in spin-orbit coupled antiferromagnets Sr2(Ir1-xGax)O4,"Antiferromagnetic (AFM) spintronics, where magneto-transport is governed by
+an antiferromagnet instead of a ferromagnet, opens fascinating new perspectives
+for both fundamental research and device technology, owing to their intrinsic
+appealing properties like rigidness to magnetic field, absence of stray field,
+and ultrafast spin dynamics. One of the urgent challenges, hindering the
+realization of the full potential of AFM spintronics, has been the performance
+gap between AFM metals and insulators. Here, we demonstrate the insulator-metal
+transition and persistently large anisotropic magnetoresistance (AMR) in single
+crystals Sr2(Ir1-xGax)O4 (0<x<0.09) which host the same basal-plane AFM lattice
+with strong spin-orbit coupling. The non-doped Sr2IrO4 shows the insulating
+transport with the AMR as big as ~16.8% at 50 K. The Ga substitution of Ir
+allows a gradual reduction of electrical resistivity, and a clear
+insulator-to-metal transition is identified in doped samples with x above 0.05,
+while the AMR can still have ~1%, sizable in comparison with those in AFM
+metals reported so far. Our experiments reveal that all the samples have the
+similar fourfold AMR symmetry, which can be well understood in the scenario of
+magnetocrystalline anisotropy. It is suggested that the spin-orbit coupled
+antiferromagnets Sr2(Ir1-xGax)O4 are promising candidate materials for AFM
+spintronics, providing a rare opportunity to integrate the superior spintronic
+functionalities of AFM metals and insulators.",2110.12852v1
+2021-12-01,Pressure dependent magnetic properties on bulk CrBr3 single crystals,"The van der Waals class of materials offer an approach to two-dimensional
+magnetism as their spin fluctuations can be tuned upon exfoliation of layers.
+Moreover, it has recently been shown that spin-lattice coupling and long-range
+magnetic ordering can be modified with pressure in van der Waals materials. In
+this work, the magnetic properties of quasi two-dimensional CrBr3 are reported
+applying hydrostatic pressure. The application of pressure (0 - 0.8 GPa) shows
+a 72 % decrease in saturation magnetization with small decrease in the Curie
+temperature from 33 to 29 K. Density functional theory calculations with
+pressure up to 1 GPa show a reduction in volume and interplanar distance as
+pressure increases. To further understand magnetic properties with applied
+pressure, the magnetocrystalline anisotropy energy (MAE) and exchange coupling
+parameter (J) are calculated. There is minimal decrease in MAE and the first
+nearest neighbor interaction (J1) (U = 2.7 eV and J = 0.7 eV), shows an
+increase in J1 with respect to pressure. Overall, CrBr3 displays ferromagnetic
+interlayer coupling and the calculated exchange coupling and MAE parameters
+match well with the observations from the experimental work.",2112.00233v1
+2021-12-06,A material view on extrinsic magnetic domain wall pinning in cylindrical CoNi nanowires,"Speed and reliability of magnetic domain wall (DW) motion are key parameters
+that must be controlled to realize the full potential of DW-based magnetic
+devices for logic and memory applications. A major hindrance to this is
+extrinsic DW pinning at specific sites related to shape and material defects,
+which may be present even if the sample synthesis is well controlled.
+Understanding the origin of DW pinning and reducing it is especially desirable
+in electrochemically-deposited cylindrical magnetic nanowires (NWs), for which
+measurements of the fascinating physics predicted by theoretical computation
+have been inhibited by significant pinning. We experimentally investigate DW
+pinning in Co$_x$Ni$_{100-x}$ NWs, by applying quasistatic magnetic fields.
+Wire compositions were varied with $x=20,30,40$, while the microstructure was
+changed by annealing or varying the pH of the electrolyte for deposition. We
+conclude that pinning due to grain boundaries is the dominant mechanism,
+decreasing inversely with both the spontaneous magnetization and grain size.
+Second-order effects include inhomogeneities in lattice strain and the residual
+magnetocrystalline anisotropy. Surface roughness, dislocations and impurities
+are not expected to play a significant role in DW pinning in these wire
+samples.",2112.03132v1
+2021-12-28,"Phonon, Electron, and Magnon Excitations in Antiferromagnetic L1$_{0}$-type MnPt","Antiferromagnetic L1$_{0}$-type MnPt is a material with relatively simple
+crystal and magnetic structure, recently attracting interest due to its high
+N{\'{e}}el temperature and wide usage as a pinning layer in magnetic devices.
+While it is experimentally well characterized, the theoretical understanding is
+much less developed, in part due to the challenging accuracy requirements
+dictated by the small underlying energy scales that govern magnetic ordering in
+antiferromagnetic metals. In this work, we use density functional theory, the
+Korringa-Kohn-Rostoker formalism, and a Heisenberg model to establish a
+comprehensive theoretical description of antiferromagnetic L1$_{0}$-type MnPt,
+along with accuracy limits, by thoroughly comparing to available literature
+data. Our simulations show that the contribution of the magnetic dipole
+interaction to the magnetocrystalline anisotropy energy of $K_{1}$=1.07$\times
+10^{6}$\,J/m$^3$ is comparable in magnitude to the spin-orbit contribution.
+Using our result for the magnetic susceptibility of $5.25\times10^{-4}$, a
+lowest magnon frequency of about 2.02\,THz is predicted, confirming THz spin
+dynamics in this material. From our data for electron, phonon, and magnon
+dispersion we compute the individual contributions to the total heat capacity
+and show that the dominant term at or above 2\,K arises from phonons. From the
+Landau-Lifshitz-Gilbert equation, we compute a N\'{e}el temperature of
+990--1070 K. Finally, we quantify the magnitude of the magneto-optical Kerr
+effect generated by applying an external magnetic field. Our results provide
+insight into the underlying physics, which is critical for a deep understanding
+of fundamental limits of the time scale of spin dynamics, stability of the
+magnetic ordering, and the possibility of magneto-optical detection of
+collective spin motion.",2112.13954v1
+2022-01-24,Direct observation of strong anomalous Hall effect and proximity-induced ferromagnetic state in SrIrO3,"The 5d iridium-based transition metal oxides have gained broad interest
+because of their strong spin-orbit coupling which favors new or exotic quantum
+electronic states. On the other hand, they rarely exhibit more mainstream
+orders like ferromagnetism due to generally weak electron-electron correlation
+strength. Here, we show a proximity-induced ferromagnetic (FM) state with TC =
+100 K and strong magnetocrystalline anisotropy in a SrIrO3 (SIO)
+heterostructure via interfacial charge transfer by using a ferromagnetic
+insulator in contact with SIO. Electrical transport allows to selectively probe
+the FM state of the SIO layer and the direct observation of a strong, intrinsic
+and positive anomalous Hall effect (AHE). For T < 20 K, the AHE displays
+unusually large coercive and saturation field, a fingerprint of a strong
+pseudospin-lattice coupling. A Hall angle, sxyAHE/sxx, larger by an order of
+magnitude than in typical 3d metals and a FM net moment of about 0.1 mB/Ir, is
+reported. This emphasizes how efficiently the nontrivial topological band
+properties of SIO can be manipulated by structural modifications and the
+exchange interaction with 3d TMOs.",2201.09570v2
+2022-06-07,Competition of Magnetocrystalline Anisotropy of Uranium Layers and Zig-Zag Chains in UNi$_{0.34}$Ge$_2$ Single Crystals,"Structural and thermodynamic properties of single-crystalline
+UNi$_{1-x}$Ge$_2$ with $x$\,=\,0.66 have been investigated by measuring
+magnetization, specific heat, and thermal expansion over a wide range of
+temperatures and magnetic fields. The measurements revealed the emergence of a
+long-range antiferromagnetic ordering of uranium magnetic moments below the
+N{\'e}el temperature $T_{\rm N}$\,=\,45.5\,K and the existence of two easy axes
+in the studied compound, namely $b$ and $c$, which correspond to the planes of
+the uranium zig-zag chains. Magnetic field applied along these two
+crystallographic directions induces in the system a first-order metamagnetic
+phase transition (from antiferromagnetism to field-polarized paramagnetism),
+and the width of the magnetic hysteresis associated with that transition
+reaches as much as 40 kOe at the lowest temperatures. A magnetic phase diagram
+developed from the experimental data showed that the metastable region
+associated with that magnetic hysteresis forms a funnel that narrows toward the
+N{\'e}el point in zero magnetic field. The four-layer Ising model has
+successfully predicted the collinear antiferromagnetic structure in
+UNi$_{0.34}$Ge$_2$ (known from earlier reports), its magnetic phase diagram,
+and temperature and field variations of its magnetization. Moreover, it
+suggests that the first-order phase transition extends down to zero magnetic
+field, although it is barely detectable in the experiments performed in low
+magnetic fields. According to this model, the second-order phase transition
+occurs in the compound only in zero field.",2206.03397v2
+2022-06-22,Spin wave stiffness and damping in a frustrated chiral helimagnet Co$_8$Zn$_8$Mn$_4$ as measured by small-angle neutron scattering,"Multiple intriguing low temperature phenomena have recently been discovered
+in the family of chiral cubic Co-Zn-Mn compounds with $\beta-$Mn-type
+structure. In particular, Co$_8$Zn$_8$Mn$_4$ displays a reduction of the
+helical spiral pitch on cooling, along with lattice shape transformations of
+metastable skyrmions and the manifestation of peculiar magnetic textures due to
+strong magnetocrystalline anisotropy. Here we report on temperature-dependent
+measurements of helimagnon excitations in the field polarized regime
+Co$_8$Zn$_8$Mn$_4$ using the spin wave small-angle neutron scattering (SWSANS)
+technique. By applying a new analytical expression to interpret the data,
+quantitative estimates for both spin wave stiffness and damping are extracted
+across a wide temperature range between 70 K and 250 K. We speculate that their
+non-trivial temperature-dependencies arise due to the effects of magnetic
+frustration arising from Mn magnetic moments, which is further reflected in
+continuous variations of both exchange and Dzyaloshinskii-Moriya interactions.",2206.11006v1
+2022-07-14,UI$_3$ -- 5f-electron magnetic van der Waals material,"We grew high-quality single crystals of the 5f electron van der Waals
+compound UI$_3$ and investigated them by measurements of specific heat and
+magnetization as functions of temperature and magnetic field. UI$_3$ behaves as
+an antiferromagnet with a first-order magnetic phase transition at the Ne\'el
+temperature $T_N$ = 2.65 K. It is characterized by a sharp symmetric
+specific-heat peak which is gradually shifted to lower temperatures by
+increasing magnetic field applied along either the a- or b-axis. The behavior
+in magnetic fields reveals orthorhombic magnetocrystalline anisotropy with the
+hard magnetization direction along the c-axis. The 2-K a- and b-axis
+magnetization curves exhibit a metamagnetic transition at the critical field
+$H_c$ = 3 T and 1.8 T, respectively. In higher fields, when the long-range
+antiferromagnetism is suppressed by a metamagnetic transition, signs of
+short-range magnetic ordering of antiferromagnetic correlations in the
+paramagnetic state show up both in specific heat and magnetization. The
+anomalous S-shape field dependence of a-axis magnetization well above $H_c$ can
+be understood as the crossover from the correlated paramagnetic regime to the
+high-field polarized paramagnet. The magnetic phase diagrams for the magnetic
+field applied along the a- and b-axis, respectively, designed using the
+mentioned experimental results are presented. We have also found that the
+UI$_3$ crystals are easily cleavable which predisposes this material for direct
+investigation of 5f electron magnetism in the 2D limit on exfoliated atomically
+thin samples.",2207.06880v1
+2022-10-25,"Au4Mn, a localized ferromagnet with strong spin-orbit coupling, long-range ferromagnetic exchange and high Curie temperature","Metallic Mn-based alloys with a nearest-neighbor Mn-Mn distance greater than
+0.4 nm exhibit large, well-localized magnetic moments. Here we investigate the
+magnetism of tetragonal Au4Mn with a Curie temperature of 385 K, where
+manganese has a spin moment of 4.1 muB and its orbital moment is quenched.
+Since 80% of the atoms are gold, the spin orbit interaction is strong and Au4Mn
+exhibits uniaxial magnetocrystalline anisotropy with surface maze domains at
+room temperature. The magnetic hardness parameter of 1.0 is sufficient to
+maintain the magnetization along the c-axis for a sample of any shape. Au also
+reduces the spin moment of Mn through 5d-3d orbital hybridization. An induced
+moment of 0.05 muB was found on Au under a pulsed field of 40 T. Density
+functional theory calculations indicate that the Mn-Mn exchange is mediated by
+spin-polarized gold 5d and 6p electrons. The distance-dependence shows that it
+is ferromagnetic or zero for the first ten shells of Mn neighbors out to 1.041
+nm (64 atoms), and very weak and oscillatory thereafter.",2210.14069v1
+2022-11-05,Designing magnetic properties in CrSBr through hydrostatic pressure and ligand substitution,"The ability to control magnetic properties of materials is crucial for
+fundamental research and underpins many information technologies. In this
+context, two-dimensional materials are a particularly exciting platform due to
+their high degree of tunability and ease of implementation into nanoscale
+devices. Here we report two approaches for manipulating the A-type
+antiferromagnetic properties of the layered semiconductor CrSBr through
+hydrostatic pressure and ligand substitution. Hydrostatic pressure compresses
+the unit cell, increasing the interlayer exchange energy while lowering the
+N\'eel temperature. Ligand substitution, realized synthetically through Cl
+alloying, anisotropically compresses the unit cell and suppresses the
+Cr-halogen covalency, reducing the magnetocrystalline anisotropy energy and
+decreasing the N\'eel temperature. A detailed structural analysis combined with
+first-principles calculations reveal that alterations in the magnetic
+properties are intricately related to changes in direct Cr-Cr exchange
+interactions and the Cr-anion superexchange pathways. Further, we demonstrate
+that Cl alloying enables chemical tuning of the interlayer coupling from
+antiferromagnetic to ferromagnetic, which is unique amongst known
+two-dimensional magnets. The magnetic tunability, combined with a high ordering
+temperature, chemical stability, and functional semiconducting properties, make
+CrSBr an ideal candidate for pre- and post-synthetic design of magnetism in
+two-dimensional materials.",2211.02788v1
+2023-02-07,Masterthesis: Ab Initio Magnetic Properties of Rare-Earth Lean Nd-based Hard Magnets,"Due to the resource criticality of rare-earths (RE), an alternative to the
+well-known Nd$_2$Fe$_{14}$B magnets with a lower amount of critical elements is
+required. In this work, density functional theory (DFT) calculations to
+investigate the influence of partial Nd substitution with more abundant
+elements (X: Y and Ce) in ThMn$_{12}$-type (Nd,X)Fe$_{11}$Ti compounds were
+performed. In order to have a systematic understanding, the intrinsic magnetic
+properties such as the saturation magnetization $M_S$, Curie temperature $T_C$
+and magnetocrystalline anisotropy energy, are screened starting from binaries
+RFe$_{12}$ (R: Y, Ce and Nd), and only considering the spin magnetic
+contribution in case of the $f$ electrons. Ti is considered for the
+thermodynamic stabilization and different concentrations of Ti are taken into
+account for ternaries RFe$_{12-y}$Ti$_y$ and quaternaries
+(Nd,X)Fe$_{12-y}$Ti$_y$ (0.5$\le$ $y$ $\le$1). In addition, the effect of
+nitrogenation is examined for each considered compound. In case of
+(Nd,Y)Fe$_{11}$Ti, $|BH|$$_{max}$ is found to be 384 kJ/m$^3$ and $T_C$ is
+calculated to be 595 K. Similarly, $|BH|$$_{max}$ and $T_C$ are calculated to
+be 365 kJ/m$^3$ and 593 K for (Nd,Ce)Fe$_{11}$Ti magnet, respectively. Both 50
+% Nd-lean magnets exhibit higher $|BH|$$_{max}$ compared to Sm$_2$Co$_{17}$ and
+$T_C$ than Nd$_2$Fe$_{14}$B. For both cases, the theoretical magnetic hardness
+factor $\kappa$ is calculated to be 1.20, which qualifies them as good
+candidates for RE-lean permanent magnets.",2302.03417v1
+2023-05-29,"Structural, Optical and Single-domain Magnetic Features of the Noncollinear Ferrimagnetic Nano-spinel Chromites ACr$_2$O$_4$ (A = Ni, Co, and Mn)","Spinel chromites ACr$_2$O$_4$ with inherent magnetic geometrical frustration
+usually exhibit a noncollinear ferrimagnetic ground state when A are magnetic
+ions, with possibly crystallite-size dependent intriguing magnetic features.
+Here, we report single-domain magnetic properties of ACr$_2$O$_4$ (A = Ni, Co,
+and Mn) nanocrystals, with an average crystallite size of 18, 15 and 10 nm,
+exhibiting an optical energy gap of 2.87, 3.05 and 2.9 eV, respectively. The
+temperature dependence of magnetization indicates the main bulk magnetic
+transitions with a commonly coexisting spin-glass-like state and finite-size
+effects on the noncolinear ferrimagnetic transitions. An anomaly observed at Ts
+= 15, 24 and 10 K is attributed to the bulk magnetic transition to a canted
+antiferromagnetic state in NiCr$_2$O$_4$ and incommensurate spiral orders in
+CoCr$_2$O$_4$ and MnCr$_2$O$_4$ NCs, respectively. A further bulk magnetic
+transition to a commensurate spiral order is observed for CoCr$_2$O$_4$ NCs at
+a lock-in temperature Tl = 5 K much lower than that reported using bulk
+samples, while it is completely suppressed in the MnCr$_2$O$_4$ NCs.
+Finite-size effects and single-domain magnetic behaviors indicated by anomalous
+temperature-dependences of the coercive field and the hysteresis-loop
+squareness, mainly driven by a magnetocrystalline anisotropy, are discussed in
+comparison to results reported using bulk counterparts.",2305.17856v1
+2023-07-20,Stray magnetic field imaging of thin exfoliated iron halides flakes,"Magnetic van der Waals materials are often proposed for use in future
+spintronic devices, aiming to leverage the combination of long-range magnetic
+order and near-atomic thinness to produce energy-efficient components. One
+class of material that has been discussed in this context are the iron halides
+FeCl$_2$ and FeBr$_2$, which are A-type antiferromagnets with strong uniaxial
+magnetocrystalline anisotropy. However, despite characterization of the bulk
+materials, the possibility for sustaining the magnetic behaviors that would
+underpin such applications in thin flakes has not been investigated. In this
+work, we use nitrogen-vacancy (NV) center microscopy to quantitatively image
+magnetism in individual exfoliated flakes of these iron halides, revealing the
+absence of magnetic remanence, a weak induced magnetization under bias field
+and variable behavior versus temperature. We show that our results are
+consistent with the antiferromagnetic behavior of the bulk material with a soft
+ferromagnetic uncompensated layer, indicating that extended ($>1~\mu$m)
+ferromagnetic domains are not sustained even at low temperatures (down to 4 K).
+Finally, we find that the magnetic order is strongly affected by the sample
+preparation, with a surprising diamagnetic order observed in a thin, hydrated
+sample.",2307.10561v1
+2023-07-28,Magnetic Antiskyrmions in Two-Dimensional van der Waals Magnets Engineered by Layer Stacking,"Magnetic skyrmions and antiskyrmions are topologically protected
+quasiparticles exhibiting a whirling spin texture in real space. Antiskyrmions
+offer some advantages over skyrmions as they are expected to have higher
+stability and can be electrically driven with no transverse motion. However,
+unlike the widely investigated skyrmions, antiskyrmions are rarely observed due
+to the required anisotropic Dzyaloshinskii-Moriya interaction (DMI). Here we
+propose to exploit the recently demonstrated van der Waals (vdW) assembly of
+two-dimensional (2D) materials that breaks inversion symmetry and creates
+conditions for anisotropic DMI. Using a 2D vdW magnet CrI${}_3$ as an example,
+we demonstrate, based on density functional theory (DFT) calculations, that
+this strategy is a promising platform to realize antiskyrmions. Polar layer
+stacking of two centrosymmetric magnetic monolayers of CrI${}_3$ efficiently
+lowers the symmetry, resulting in anisotropic DMI that supports antiskyrmions.
+The DMI is reversible by switching the ferroelectric polarization inherited
+from the polar layer stacking, offering the control of antiskyrmions by an
+electric field. Furthermore, we find that the magnetocrystalline anisotropy and
+DMI of CrI${}_3$ can be efficiently modulated by Mn doping, creating a
+possibility to control the size of antiskyrmions. Using atomistic spin dynamics
+simulations with the parameters obtained from our DFT calculations, we predict
+the formation of antiskyrmions in a Cr${}_{0.88}$Mn${}_{0.12}$I${}_3$ bilayer
+and switching their spin texture with polarization reversal. Our results open a
+new direction to generate and control magnetic antiskyrmions in 2D vdW magnetic
+systems.",2307.15769v1
+2023-09-16,Strain tuned magnetotransport of Jeff=1/2 antiferromagnetic Sr2IrO4 thin films,"In this work, we report observation of strain effect on physical properties
+of Sr2IrO4 thin films grown on SrTiO3 (001) and LaAlO3 (001) substrates. It is
+found that the film on LaAlO3 with compressive strain has a lower
+antiferromagnetic transition temperature (TN~210 K) than the film on SrTiO3
+(TN~230 K) with tensile strain, which is probably caused by modified interlayer
+coupling. Interestingly, magnetoresistance due to pseudospin-flip of the film
+on LaAlO3 is much larger than that of tensile-strained film on SrTiO3, and
+robust anisotropic magnetoresistance is observed in the former, but H-driven
+reversal behavior is seen in the latter. By performing first principles
+calculations, it is revealed that epitaxial strain plays an efficient role in
+tuning the canting angle of Jeff=1/2 moments and thus net moment at every IrO2
+layer, responsible for the difference in magnetoresistance between the films.
+The reversal of anisotropic magnetoresistance in the thin film on SrTiO3 can be
+ascribed to stabilization of a metastable stable with smaller bandgap as the
+Jeff=1/2 moments are aligned along the diagonal of basal plane by H. However,
+theoretical calculations reveal much higher magnetocrystalline anisotropy
+energy in the film on LaAlO3. This causes difficulties to drive the Jeff=1/2
+moments to reach the diagonal and thereby the metastable state, explaining the
+distinct anisotropic magnetoresistance between two samples in a qualitative
+sense. Our findings indicate that strain can be a highly efficient mean to
+engineer the functionalities of Jeff=1/2 antiferromagnet Sr2IrO4.",2309.08981v1
+2024-01-10,Observation of correlation induced metal to half-metal phase transition and large orbital moment in $\mathrm{Sr_2CoO_4}$,"We present a detailed mean-field study to address the fundamental discrepancy
+in the ground state magnetization of $\mathrm{Sr_{2}CoO_{4}}$ (SCO). In
+contrast to the ferromagnetic metallic ground state obtained from density
+functional theory (DFT), DFT+$U$ gives three ferromagnetic solutions converging
+to integer moment values (1, 2 \& 3 $\mu_B$/f.u) over a range of $U$.
+Interestingly, two of the solutions are found to exhibit half-metallicity with
+correspondingly $S$=1/2 and S=3/2 spin states. The half-metallic ferromagnetic
+state with $S$=3/2 is found to be the ground state solution for SCO. Co atoms
+show a large deviation from the formal +4 oxidation state indicating the
+presence of strong covalency effects. Our results suggest a plausible metal to
+half-metal phase transition around $U$($J$)=4.4(1.16) eV. The Fermi surface
+study shows gradual collapse in states leading to half-metallicity suggesting
+\textit{\textbf{k}}-dependence of effective $U$ around the critical region.
+Surprisingly, in the presence of spin-orbit coupling (SOC), unexpectedly large
+orbital moment ($L_{z}$=0.6) is noted in SCO putting it among the class of 3$d$
+based transition metal compounds exhibiting pronounced orbital magnetization.
+The calculations give large magnetocrystalline anisotropy energy (MAE) of
+$\sim$48 meV. Large values of orbital magnetic moment contribution and MAE, in
+the presence of strong correlation effects, provide a better interpretation of
+experimental magnetization observed in SCO.",2401.05149v1
+2024-03-27,"$J_{eff}$ states in a quasi one dimensional antiferromagnetic spin chain hexagonal Iridates Sr$_3$MIrO$_6$ (M=Mg, Zn, Cd): an $ab-initio$ comparative perspective","We employ first-principles density-functional theory, to perform a
+comparative investigation of the effect of the spin-orbit coupling (SOC) on the
+electronic and magnetic properties of three experimentally synthesized and
+characterized hexagonal perovskites Sr$_3$MIrO$_6$(M=Mg, Zn, Cd). The
+electronic structure calculations show that in all the compounds, Ir is the
+only magnetically active site in +4[5$d^5$] configuration, whereas M$^{+2}$
+(M=Cd, Zn, Mg), remains in nonmagnetic states with Cd/Zn and Mg featuring
+$d^{10}$ and $d^{0}$ electronic configurations, respectively. The insulating
+gap could be opened by switching on the correlation parameter $U$ for
+Sr$_3$CdrO$_6$ and Sr$_3$ZnIrO$_6$ which qualifies it to be a correlated Mott
+insulator. However, in the case of Sr$_3$MgIrO$_6$ both $U$ and
+antiferromagnetic ordering is not enough and the gap could only be opened by
+including the SOC which classifies it to fall under the category of a typical
+SOC Mott insulator. The $j_{eff}$ states are visualized from the orbital
+projected band structure. The magnetism is studied from the point of view of
+exchange interactions and magnetocrystalline anisotropy in the presence of the
+SOC. We also present the comparative analysis of the renormalized impact of SOC
+on the three compounds, which shows that all the three compounds fall under the
+$intermediate$ coupling regime, where Sr$_3$MgIrO$_6$ is comparatively closer
+to the atomic $j_{eff}=\frac{1}{2}$ picture from the others.",2403.18408v1
+2011-07-16,Intrinsic anomalous Hall effect in nickel: An GGA+U study,"The electronic structure and intrinsic anomalous Hall conductivity of nickel
+have been calculated based on the generalized gradient approximation (GGA) plus
+on-site Coulomb interaction (GGA+U) scheme. It is found that the intrinsic
+anomalous Hall conductivity ($\sigma_{xy}^H$) obtained from the GGA+U
+calculations with $U = 1.9$ eV and $J=1.2$ eV, is in nearly perfect agreement
+with that measured recently at low temperatures while, in contrast, the
+$\sigma_{xy}^H$ from the GGA calculations is about 100% larger than the
+measured one. This indicates that, as for the other spin-orbit interaction
+(SOI)-induced phenomena in 3$d$ itinerant magnets such as the orbital magnetic
+magnetization and magnetocrystalline anisotropy, the on-site electron-electron
+correlation, though moderate only, should be taken into account properly in
+order to get the correct anomalous Hall conductivity. The intrinsic
+$\sigma_{xy}^H$ and the number of valence electrons ($N_e$) have also been
+calculated as a function of the Fermi energy ($E_F$). A sign change is
+predicted at $E_F = -0.38$ eV ($N_e = 9.57$), and this explain qualitatively
+why the theoretical and experimental $\sigma_{xy}^H$ values for Fe and Co are
+positive. It is also predicted that fcc Ni$_{(1-x)}$Co(Fe,Cu)$_x$ alloys with
+$x$ being small, would also have the negative $\sigma_{xy}^H$ with the
+magnitude being in the range of $500\sim 1400$ $\Omega^{-1}$cm$^{-1}$. The most
+pronounced effect of including the on-site Coulomb interaction is that all the
+$d$-dominant bands are lowered in energy relative to the $E_F$ by about 0.3 eV,
+and consequently, the small minority spin X$_2$ hole pocket disappears. The
+presence of the small X$_2$ hole pocket in the GGA calculations is attributed
+to be responsible for the large discrepancy in the $\sigma_{xy}^H$ between
+theory and experiment.",1107.3242v2
+2016-04-28,Dynamics of skyrmionic states in confined helimagnetic nanostructures,"In confined helimagnetic nanostructures, skyrmionic states in the form of
+incomplete and isolated skyrmion states can emerge as the ground state in
+absence of both external magnetic field and magnetocrystalline anisotropy. In
+this work, we study the dynamic properties (resonance frequencies and
+corresponding eigenmodes) of skyrmionic states in thin film FeGe disk samples.
+We employ two different methods in finite-element based micromagnetic
+simulation: eigenvalue and ringdown method. The eigenvalue method allows us to
+identify all resonance frequencies and corresponding eigenmodes that can exist
+in the simulated system. However, using a particular experimentally feasible
+excitation can excite only a limited set of eigenmodes. Because of that, we
+perform ringdown simulations that resemble the experimental setup using both
+in-plane and out-of-plane excitations. In addition, we report the nonlinear
+dependence of resonance frequencies on the external magnetic bias field and
+disk sample diameter and discuss the possible reversal mode of skyrmionic
+states. We compare the power spectral densities of incomplete skyrmion and
+isolated skyrmion states and observe several key differences that can
+contribute to the experimental identification of the state present in the
+sample. We measure the FeGe Gilbert damping, and using its value we determine
+what eigenmodes can be expected to be observed in experiments. Finally, we show
+that neglecting the demagnetisation energy contribution or ignoring the
+magnetisation variation in the out-of-film direction - although not changing
+the eigenmode's magnetisation dynamics significantly - changes their resonance
+frequencies substantially. Apart from contributing to the understanding of
+skyrmionic states physics, this systematic work can be used as a guide for the
+experimental identification of skyrmionic states in confined helimagnetic
+nanostructures.",1604.08347v2
+2018-12-26,"Hydrodynamic description of long-distance spin transport through noncollinear magnetization states: the role of dispersion, nonlinearity, and damping","Nonlocal compensation of magnetic damping by spin injection has been
+theoretically shown to establish dynamic, noncollinear magnetization states
+that carry spin currents over micrometer distances. Such states can be
+generically referred to as dissipative exchange flows (DEFs) because spatially
+diffusing spin currents are established by the mutual exchange torque exerted
+by neighboring spins. Analytical studies to date have been limited to the weak
+spin injection assumption whereby the equation of motion for the magnetization
+is mapped to hydrodynamic equations describing spin flow and then linearized.
+Here, we analytically and numerically study easy-plane ferromagnetic channels
+subject to spin injection of arbitrary strength at one extremum under a unified
+hydrodynamic framework. We find that DEFs generally exhibit a nonlinear profile
+along the channel accompanied by a nonlinear frequency tuneability. At large
+injection strengths, we fully characterize a novel magnetization state we call
+a contact-soliton DEF (CS-DEF) composed of a stationary soliton at the
+injection site, which smoothly transitions into a DEF and exhibits a negative
+frequency tuneability. The transition between a DEF and a CS-DEF occurs at the
+maximum precessional frequency and coincides with the Landau criterion: a
+subsonic to supersonic flow transition. Leveraging the hydraulic-electrical
+analogy, the current-voltage characteristics of a nonlinear DEF circuit are
+presented. Micromagnetic simulations of nanowires that include
+magnetocrystalline anisotropy and non-local dipole fields are in qualitative
+agreement with the analytical results. The magnetization states found here
+along with their characteristic profile and spectral features provide
+quantitative guidelines to pursue an experimental demonstration of DEFs in
+ferromagnetic materials and establishes a unified description for long-distance
+spin transport.",1812.10438v3
+2019-12-07,Suppression of the skyrmion Hall effect in planar nanomagnets by the magnetic properties engineering: Skyrmion transport on nanotracks with magnetic strips,"Micromagnetic simulations have been performed to investigate the suppression
+of the skyrmion Hall effect in nanotracks with their magnetic properties
+strategically modified. In particular, we study two categories of magnetically
+modified nanotracks. One of them, repulsive edges have been inserted in the
+nanotrack and, in the other, an attractive strip has been placed exactly on the
+longest axis of the nanotrack. Attractive and repulsive interactions can be
+generated from the engineering of magnetic properties. For instance, it is
+known that the skyrmion can be attracted to a region where the exchange
+stiffness constant is decreased. On the other hand, the skyrmion can be
+repelled from a region characterized by a local increase in the exchange
+stiffness constant. In order to provide a background for experimental studies,
+we vary not only the magnetic material parameters (exchange stiffness,
+perpendicular magnetocrystalline anisotropy and the Dzyaloshinskii-Moriya
+constant) but also the width of the region magnetically modified, containing
+either a local reduction or a local increase for each one of these magnetic
+properties. In the numerical simulations, the skyrmion motion was induced by a
+spin-polarized current and the found results indicate that it is possible to
+transport skyrmions around the longest axis of the nanotrack. In practice, the
+skyrmion Hall effect can be completely suppressed in magnetic nanotracks with
+strategically modified magnetic properties. Furthermore, we discuss in detail 6
+ways to suppress the skyrmion Hall effect by the usage of nanotracks with
+repulsive edges and nanotracks with an attractive strip.",1912.03403v2
+2019-12-07,Tailoring magnetic interactions in atomic bilayers of Rh and Fe on Re(0001),"Using density functional theory, we investigate the interplay between the
+stacking order and sequence of bilayers composed of an Fe and a Rh layer on the
+Re(0001) and their magnetic properties. We find that fcc/ffc stacked bilayers
+are energetically very unfavorable, while all other combinations of hcp and fcc
+stacking are energetically close. The magnetic interactions are evaluated by
+mapping the DFT total energies onto a spin model, which contains Heisenberg
+exchange, Dzyaloshinskii-Moriya interaction, the magnetocrystalline anisotropy
+energy, and higher-order exchange interactions. We find that the stacking
+sequence of the bilayer significantly modifies the magnetic interactions. As a
+result, we find a DMI driven cycloidal spin spiral ground state with a period
+of 11~nm for hcp-Fe/hcp-Rh. For fcc-Fe/hcp-Rh and hcp-Fe/fcc-Rh, we obtain a
+ferromagnetic ground state. The spin spiral energy dispersion of hcp-Fe/hcp-Rh
+including spin-orbit coupling suggests that isolated skyrmions can be
+stabilized in the field-polarized ferromagnetic background at external magnetic
+fields. If the Fe layer is sandwiched between the Rh overlayer and the Re(0001)
+substrate, there is a competition between the ferromagnetic coupling preferred
+by the Rh-Fe hybridization and the antiferromagnetic coupling induced by the
+Fe-Re hybridization. Due to the Fe/Re interface the DMI can become very large.
+For fcc-Rh/hcp-Fe, we obtain a cycloidal spin spiral with a period of 1.7~nm
+which is induced by frustration of exchange interactions and further stabilized
+by the DMI. For hcp-Rh/hcp-Fe, we find a DMI driven cycloidal spin spiral with
+a period of 4~nm and locally nearly antiparallel magnetic moments due to
+antiferromagnetic nearest-neighbor exchange. The higher-order exchange
+constants can be significant in the considered films, however, they do not
+stabilize multi-$Q$ states.",1912.03465v2
+2019-12-20,Spontaneous and externally driven quantum spin fluctuations of 3d and 4d single atoms adsorbed on graphene,"At the heart of current information nanotechnology lies the search for ideal
+platforms hosting the smallest possible magnets, i.e. single atoms with
+magnetic moments pointing out-of-plane, as requested in a binary-type of
+memory. For this purpose, a 2D material such as graphene would be an ideal
+substrate thanks to its intrinsic low electron and phonon densities, as well as
+its 6-fold symmetry. Here we investigate, from first-principles, a fundamental
+mechanism detrimental for the magnetic stability: the zero-point
+spin-fluctuations modifying the effective energy landscape perceived by the
+local spin moments of 3$d$ and 4$d$ transition metal atoms deposited on a free
+standing graphene. Utilizing time-dependent density functional theory and by
+virtue of the fluctuation-dissipation theorem, these spontaneous quantum
+fluctuations are found to be negligible for most of the 3$d$ elements, in
+strong contrast to the 4$d$ atoms. Surprisingly, we find that such fluctuations
+can promote the magnetic stability by switching the easy direction of the
+magnetic moment of Tc from being initially in-plane to out-of-plane. The
+adatom-graphene complex gives rise to impurity states settling in some cases
+the magnetocrystalline anisotropy energy --- the quantity that defines the
+energy barrier protecting the magnetic moments and, consequently, the
+spin-excitation behavior detectable with inelastic scanning tunneling
+spectroscopy. A detailed analysis is provided on the impact of electron-hole
+excitations, damping and lifetime of the spin-excitations on the dynamical
+behavior of the adsorbed magnetic moments on graphene.",1912.09938v1
+2020-10-22,"Structure, magnetism and electronic properties in 3$d$-5$d$ based double perovskite (Sr$_{1-x}$Ca$_x$)$_2$FeIrO$_6$ (0 $\leq$ $x$ $\leq$ 1): A combined experimental and theoretical investigation","The 3$d$-5$d$ based double perovskites offer an ideal playground to study the
+interplay between electron correlation ($U$) and spin-orbit coupling (SOC)
+effect, showing exotic physics. The Sr$_2$FeIrO$_6$ is an interesting member in
+this family with ionic distribution of Fe$^{3+}$ (3$d^5$) and Ir$^{5+}$
+(5$d^4$) where the later is believed to be nonmagnetic under the picture of
+strong SOC. Here, we report detailed investigation of structural, magnetic and
+electronic transport properties along with electronic structure calculations in
+(Sr$_{1-x}$Ca$_x$)$_2$FeIrO$_6$ series with $x$ from 0 to 1. While the basic
+interactions such as, $U$ and SOC are unlikely to be modified but a structural
+modification is expected due to ionic size difference between Sr$^{2+}$ and
+Ca$^{2+}$ which would influence other properties such as crystal field effect
+and band widths. While a nonmonotonic changes in lattice parameters are
+observed across the series, the spectroscopic investigations reveal that 3+/5+
+charge state of Fe/Ir continue till end of the series. An analysis of magnetic
+data suggests similar nonmonotonic evolution of magnetic parameters with
+doping. Temperature dependent crystal structure as well as low temperature (5
+K) magnetic structure have been determined from neutron powder diffraction
+measurements. The whole series shows insulating behavior. The electronic
+structure calculations show, SOC enhanced, a noncollinear antiferromagnetic and
+Mott-type insulating state is the stable ground state for present series with a
+substantial amount of orbital moment, but less than the spin magnetic moment,
+at the Ir site and the magnetocrystalline anisotropy. The obtained results
+imply that the Ca$^{2+}$ has large influence on the magnetic and transport
+properties, further showing a large agreement between experimental results as
+well as theoretical calculations.",2010.11412v1
+2021-01-03,Magnetic surface reconstruction in the van-der-Waals antiferromagnet Fe$_{1+x}$Te,"Fe$_{1+x}$Te is a two dimensional van der Waals antiferromagnet that becomes
+superconducting on anion substitution on the Te site. The parent phase of
+Fe$_{1+x}$Te is sensitive to the amount of interstitial iron situated between
+the iron-tellurium layers displaying collinear magnetic order coexisting with
+low temperature metallic resistivity for small concentrations of interstitial
+iron $x$ and helical magnetic order for large values of $x$. While this phase
+diagram has been established through scattering [see for example E. E.
+Rodriguez $\textit{et al.}$ Phys. Rev. B ${\bf{84}}$, 064403 (2011) and S.
+R\""ossler $\textit{et al.}$ Phys. Rev. B ${\bf{84}}$, 174506 (2011)], recent
+scanning tunnelling microscopy measurements [C. Trainer $\textit{et al.}$ Sci.
+Adv. ${\bf{5}}$, eaav3478 (2019)] have observed a different magnetic structure
+for small interstitial iron concentrations $x$ with a significant canting of
+the magnetic moments along the crystallographic $c$ axis of $\theta$=28 $\pm$
+3$^{\circ}$. In this paper, we revisit the magnetic structure of Fe$_{1.09}$Te
+using spherical neutron polarimetry and scanning tunnelling microscopy to
+search for this canting in the bulk phase and compare surface and bulk
+magnetism. The results show that the bulk magnetic structure of Fe$_{1.09}$Te
+is consistent with collinear in-plane order ($\theta=0$ with an error of $\sim$
+5$^{\circ}$). Comparison with scanning tunnelling microscopy on a series of
+Fe$_{1+x}$Te samples reveals that the surface exhibits a magnetic surface
+reconstruction with a canting angle of the spins of $\theta=29.8^{\circ}$. We
+suggest that this is a consequence of structural relaxation of the surface
+layer resulting in an out-of-plane magnetocrystalline anisotropy. The magnetism
+in Fe$_{1+x}$Te displays different properties at the surface when the symmetry
+constraints of the bulk are removed.",2101.00569v1
+2021-04-06,Magnetic imaging and statistical analysis of the metamagnetic phase transition of FeRh with electron spins in diamond,"Magnetic imaging based on nitrogen-vacancy (NV) centers in diamond has
+emerged as a powerful tool for probing magnetic phenomena in fields ranging
+from biology to physics. A key strength of NV sensing is its local-probe
+nature, enabling high-resolution spatial images of magnetic stray fields
+emanating from a sample. However, this local character can also form a drawback
+for analysing the global properties of a system, such as a phase transition
+temperature. Here, we address this challenge by using statistical analyses of
+magnetic-field maps to characterize the first-order temperature-driven
+metamagnetic phase transition from the antiferromagnetic to the ferromagnetic
+state in FeRh. After imaging the phase transition and identifying the regimes
+of nucleation, growth, and coalescence of ferromagnetic domains, we
+statistically characterize the spatial magnetic-field maps to extract the
+transition temperature and thermal hysteresis width. By analysing the spatial
+correlations of the maps and their dependence on an external magnetic field, we
+investigate the magnetocrystalline anisotropy and detect a reorientation of
+domain walls across the phase transition. The employed statistical approach can
+be extended to the study of other magnetic phenomena with NV magnetometry or
+other sensing techniques.",2104.02814v1
+2021-04-28,Structural transformation and magnetic properties of (Fe$_{0.7}$Co$_{0.3}$)$_2$B alloys doped with 5$d$ elements: A combined first-principles and experimental study,"(Fe,Co)$_2$B-based compounds with specified 5$d$ substitutions are considered
+as promising materials for permanent magnets without rare-earth elements. We
+conducted a combined first-principles and experimental study focused on
+(Fe$_{0.7}$Co$_{0.3}$)$_2$B alloys doped with W and Re. First, we used
+full-potential local-orbital scheme to systematically investigate (Fe,Co)$_2$B
+alloys with 3$d$, 4$d$, and 5$d$ substitutions. Computational analyses showed a
+significant increase in magnetocrystalline anisotropy only for the Re doped
+sample. Simultaneously, the structural and magnetic properties of the
+(Fe$_{0.7-x}$Co$_{0.3-x}$M$_{2x}$)$_2$B ($M$ = W, Re; $x$ = 0, 0.025) alloys
+were investigated experimentally. The desired (Fe,Co)$_2$B tetragonal phase was
+synthesized by heat treatment of amorphous precursors. We observed that
+isothermal annealing increases the coercive field of all samples. However, the
+obtained values, without further optimization, are well below the threshold for
+permanent magnet applications. Nevertheless, annealing of substituted samples
+at 750$^o$C significantly improves saturation magnetization values.
+Furthermore, M\""{o}ssbauer spectroscopy revealed a reduction of the hyperfine
+field due to the presence of Co atoms in the (Fe,Co)$_2$B phase, where
+additional defect positions are formed by Re and W. Radio-frequency
+M\""{o}ssbauer studies showed that (Fe$_{0.7}$Co$_{0.3}$)$_2$B and the
+W-substituted sample began to crystallize when exposed to an radio frequency
+field of 12 Oe, indicating that the amorphous phase is stabilized by Re
+substitution. Improvement of thermal stability of
+(Fe$_{0.675}$Co$_{0.275}$Re$_{0.05}$)$_2$B alloy is consistent with the results
+of differential scanning calorimetry and thermomagnetic measurements.",2104.13724v2
+2022-07-22,FORC Diagram Features of Co Particles due to Reversal by Domain Nucleation,"First Order Reversal Curve (FORC) diagrams are a popular tool in geophysics
+and materials science for the characterization of magnetic particles of natural
+and synthetic origin. However, there is still a lot of controversy about the
+rigorous interpretation of the origin of certain features in a FORC diagram. In
+this study, we analyze FORCs computed by micromagnetic simulations of Co cubes
+with dimensions of 50, 100 and 150 nm and uniaxial magnetocrystalline
+anisotropy. For the larger cubes we observe the formation of a stable
+two-domain state. The nucleation of a reversed domain and its subsequent
+annihilation are clearly visible as separate peaks in the FORC diagram. They
+spread out along the coordinate axis in the FORC diagram, which is associated
+with the bias field $H_U$ of a Preisach hysteron. Based on our findings, we
+state that a FORC diagram peak spreading along the $H_U$ axis can have its
+origin in the step-wise magnetization reversal driven by nucleation of domains
+in a single particle. This means that we have identified another mechanism
+apart from the well-known magnetostatic interaction between a set of particles
+that leads to features in the FORC diagram extending along the $H_U$-axis. Our
+study demonstrates that if FORCs shall be used as a quantitative tool to assess
+the microstructure of samples containing magnetic material, more information
+from other methods will be required to identify the correct physical mechanism
+by which a certain ""fingerprint"" in a FORC diagram is produced.",2207.11011v1
+2022-10-27,Tuning the magnetic interactions in van der Waals Fe$_3$GeTe$_2$ heterostructures: A comparative study of \textit{ab initio} methods,"We investigate the impact of mechanical strain, stacking order, and external
+electric fields on the magnetic interactions of a two-dimensional (2D) van der
+Waals (vdW) heterostructure in which a 2D ferromagnetic metallic Fe$_3$GeTe$_2$
+monolayer is deposited on germanene. Three distinct computational approaches
+based on \textit{ab initio} methods are used, and a careful comparison is
+given: (i) The Green's function method, (ii) the generalized Bloch theorem, and
+(iii) the supercell approach. First, the shell-resolved exchange constants are
+calculated for the three Fe atoms within the unit cell of the freestanding
+Fe$_3$GeTe$_2$ monolayer. We find that the results between methods (i) and (ii)
+are in good qualitative agreement and also with previously reported values. An
+electric field of ${\cal E}= \pm 0.5$~V/{\AA} applied perpendicular to the
+Fe$_3$GeTe$_2$/germanene heterostructure leads to significant changes of the
+exchange constants. We show that the Dzyaloshinskii-Moriya interaction (DMI) in
+Fe$_3$GeTe$_2$/germanene is mainly dominated by the nearest neighbors,
+resulting in a good quantitative agreement between methods (i) and (ii).
+Furthermore, we demonstrate that the DMI is highly tunable by strain, stacking,
+and electric field, leading to a large DMI comparable to that of
+ferromagnetic/heavy metal (FM/HM) interfaces. The geometrical change and
+hybridization effect explain the origin of the high tunability of the DMI at
+the interface. The electric-field driven DMI obtained by method (iii) is in
+qualitative agreement with the more accurate \textit{ab initio} method used in
+approach (ii). However, the field-effect on the DMI is overestimated by method
+(iii) by about 50\%. The magnetocrystalline anisotropy energy can also be
+drastically changed by the application of compressive or tensile strain in the
+Fe$_3$GeTe$_2$/germanene heterostructure.",2210.15351v2
+2022-11-28,Orbital-selective Mott phase and spin nematicity in Ni-substituted FeTe$_{0.65}$Se$_{0.35}$ single crystals,"The normal state in iron chalcogenides is metallic but highly unusual, with
+orbital and spin degrees of freedom partially itinerant or localized depending
+on temperature, leading to many unusual features. In this work, we report on
+the observations of two of such features, the orbital selective Mott phase
+(OSMP) and spin nematicity, evidenced in magnetization and magnetotransport
+[resistivity, Hall effect, anisotropic magnetoresistance (AMR)] of
+Fe$_{1-y}$Ni$_y$Te$_{0.65}$Se$_{0.35}$ single crystals, with $0 < y < 0.21$.
+Substitution of Ni dopes crystals with electrons, what eliminates some of the
+hole pockets from Fermi level, leaving only one, originating from $d_{xy}$
+orbital. This leads to electron-dominated conduction at low $T$ for $y \gtrsim
+0.06$. However, at high temperatures, $T \gtrsim 125 \div 178$ K, the
+conduction reverses to hole-dominated. Anomalies in magnetization and
+resistivity are observed at temperatures which approach high-$T$ boundary of
+the electron-dominated region. Analysis of these effects suggests a link with
+the appearance of the $d_{z^2}$ hole pockets at X points of the Brillouin zone
+in the OSMP phase, facilitated by the localization of $d_{xy}$ orbital, as
+recently reported by angular resolved photoemission experiments ($\textit{J.
+Huang et al., Commun. Phys. 5, 29 (2022)}$). The low-$T$ AMR shows mixed 4-fold
+and 2-fold rotational symmetry of in-plane magnetocrystalline anisotropy, with
+the 4-fold term the largest at small $y$, and suppressed at intermediate $y$.
+These results are consistent with the mixed stripe/bicollinear magnetic
+correlations at small $y$, and suppression of stripe correlations at
+intermediate $y$, indicating development of spin nematicity with increasing Ni
+doping, which possibly contributes to the suppression of superconductivity.",2211.15189v3
+2023-06-16,Tailoring defects and nanocrystal transformation for optimal heating power in bimagnetic $Co_yFe_{1-y}O@Co_xFe_{3-x}O_4$ particles,"The effects of cobalt incorporation in spherical heterostructured iron oxide
+nanocrystals (NCs) of sub-critical size have been explored by colloidal
+chemistry methods. Synchrotron X-ray total scattering methods suggest that
+cobalt (Co) substitution in rock salt iron oxide NCs tends to remedy its vacant
+iron sites, offering a higher degree of resistance to oxidative conversion.
+Self-passivation still creates a spinel-like shell, but with higher volume
+fraction of the rock salt Co-containing phase in the core. The higher divalent
+metal stoichiometry in the rock salt phase, with increasing Co content, results
+in a population of unoccupied tetrahedral metal sites in the spinel part,
+likely through oxidative shell creation, involving an ordered defect-clustering
+mechanism, directly correlated to the core stabilization. To shed light on the
+effects of Co-substitution and atomic-scale defects (vacant sites), Monte Carlo
+simulations suggest that designed NCs, with desirable, enhanced magnetic
+properties (cf. exchange bias and coercivity), are developed with
+magnetocrystalline anisotropy raised at relatively low content of Co ions in
+the lattice. Growth of optimally performing candidates combines also a strongly
+exchange-coupled system, secured through a high volumetric ratio rock salt
+phase, interfaced by a not so defective spinel shell. In view of these
+requirements, Specific Absorption Rate (SAR) calculations demonstrate that the
+sufficiently protected from oxidation rock salt core and preserved over time
+heterostructure, play a key role in magnetically-mediated heating efficacies,
+for potential use of such NCs in magnetic hyperthermia applications.",2306.09684v1
+2023-07-11,Structural and magnetic properties of Fe-Co-C alloys with tetragonal deformation: a first-principle study,"Fe-Co alloys with induced tetragonal strain are promising materials for
+rare-earth-free permanent magnets. However, as ultrathin-film studies have
+shown, tetragonal Fe-Co structures tend to a rapid relaxation toward a cubic
+structure as the thickness of the deposited film increases. One of the main
+methods of inducing the stable strain in the bulk material is interstitial
+doping with small atoms, like B, C, or N. In this work, we present a full
+configuration space analysis in density functional theory approach for
+(Fe$_{1-x}$Co$_x$)$_{16}$C supercells with a single C impurity in one of the
+octahedral interstitial positions and for the full range of Co concentrations
+$x$. We discuss all assumptions and considerations leading to calculated
+lattice parameters, mixing enthalpies, magnetic moments, and averaged
+magnetocrystalline anisotropy energies (MAE). We present a comprehensive
+qualitative analysis of the structural and magnetic properties' dependence on
+short- and long-range ordering parameters. We analyzed all unique Fe/Co atoms
+occupancies at all stoichiometric concentrations possible in 2x2x2 supercell
+based on 2-atom tetragonal representation. We rely on the thermodynamic
+averaging method and large sample count to obtain accurate MAE values. We
+reevaluate several chemical disorder approximation methods, including effective
+medium methods (virtual crystal approximation and coherent potential
+approximation) and special quasirandom structures method applied to Fe-Co-based
+alloys. We observe a structural phase transition from the body-centered
+tetragonal structure above 70% Co concentration and confirm the structural
+stability of Fe-Co-C alloys in the tetragonal range. We show the presence of a
+broad MAE maximum of around 50% Co concentration and notably high MAE values
+for Co content $x$ as low as 25%. In addition, we show a positive correlation
+between MAE and mixing enthalpy.",2307.05709v1
+2023-12-07,Tuning magnetic interactions of Co and 4$d$ transition-metal atomic bilayers on Re(0001) via interface engineering,"Employing $\textit{ab-initio}$ density functional theory (DFT), we performed
+a systematic investigation of the electronic structures and the magnetic
+properties of atomic bilayers composed of a 4$d$ transition-metal layer (Rh, Pd
+and Ru) and a Co layer on the Re(0001) surface. Our DFT calculations reveal the
+influence of the bilayer composition and their stacking sequence on the
+magnetic ground state and magnetic interactions. We obtain the magnetic
+interactions by mapping the total energies onto an effective spin Hamiltonian
+which contains the exchange interaction and the Dzyaloshinskii-Moriya
+interaction (DMI) as well as the magnetocrystalline anisotropy energy (MAE). We
+observe noticeable changes in bilayer hybridization due to variation in bilayer
+composition and overlayer symmetry, leading to significant variation in
+magnetic interactions. In all considered systems, the nearest-neighbor exchange
+interaction is ferromagnetic, however, the value varies by up to a factor of 5.
+The effective, nearest-neighbor DMI constant exhibits variation in sign over
+the films considered, favoring either right- (clockwise) or left-handed
+(anticlockwise) cycloidal spin spirals. The value of the DMI changes by up to a
+factor of 27 among the films. For most of the systems, the MAE favors an
+out-of-plane easy magnetization axis, however, for hcp-Co/Rh and hcp-Co/Ru
+bilayers on Re(0001), it prefers an in-plane magnetization axis. The magnitude
+of the MAE varies from a small value of about 0.1 meV/Co atom up to about 2
+meV/Co atom for Co/Pd bilayers. The spin spiral energy dispersion curve rises
+quite quickly close to the ferromagnetic state for films in which the Co layer
+is adjacent to the vacuum indicating a large effective exchange constant which
+stabilizes a ferromagnetic ground state in Co/$4d$ bilayers on Re(0001).",2312.04409v1
+2024-02-29,"Magnetism, heat capacity and electronic structure of EuCd$_2$P$_2$ in view of its colossal magnetoresistance","The mechanism of the peculiar transport properties around the magnetic
+ordering temperature of semiconducting antiferromagnetic EuCd$_2$P$_2$ is not
+yet understood. With a huge peak in the resistivity observed above the N\'eel
+temperature, $T_{\rm N}=10.6\,\rm K$, it exhibits a colossal magnetoresistance
+effect. Recent reports on observations of ferromagnetic contributions above
+$T_{\rm N}$ as well as metallic behavior below this temperature have motivated
+us to perform a comprehensive characterization of this material, including its
+resistivity, heat capacity, magnetic properties and electronic structure. Our
+transport measurements revealed quite different temperature dependence of
+resistivity with the maximum at $14\,\rm K$ instead of previously reported
+$18\,\rm K$. Low-field susceptibility data support the presence of static
+ferromagnetism above $T_{\rm N}$ and show a complex behavior of the material at
+small applied magnetic fields. Namely, signatures of reorientation of magnetic
+domains are observed up to $T=16\,\rm K$. Our magnetization measurements
+indicate a magnetocrystalline anisotropy which also leads to a preferred
+alignment of the magnetic clusters above $T_{\rm N}$. The momentum-resolved
+photoemission experiments at temperatures from $24\,\rm K$ down to $2.5\,\rm K$
+indicate the permanent presence of a fundamental band gap without change of the
+electronic structure when going through $T_N$ that is in contradiction with
+previous results. We performed \textit{ab initio} band structure calculations
+which are in good agreement with the measured photoemission data when assuming
+an antiferromagnetic ground state. Calculations for the ferromagnetic phase
+show a much smaller bandgap, indicating the importance of possible
+ferromagnetic contributions for the explanation of the colossal
+magnetoresistance effect in the related EuZn$_2$P$_2$.",2402.18911v1
+2017-12-15,Anisotropic magneto-crystalline coupling of the skyrmion lattice in MnSi,"We investigate the anisotropic nature of magnetocrystalline coupling between
+the crystallographic and skyrmion crystal (SKX) lattices in the chiral magnet
+MnSi by magnetic field-angle resolved resonant ultrasound spectroscopy. Abrupt
+changes are observed in the elastic moduli and attenuation when the magnetic
+field is parallel to the [011] crystallographic direction. These observations
+are interpreted in a phenomenological Ginzburg-Landau theory that identifies
+switching of the SKX orientation to be the result of an anisotropic
+magnetocrystalline coupling potential. Our paper sheds new light on the nature
+of magnetocrystalline coupling potential relevant to future spintronic
+applications.",1712.05479v2
+1998-10-31,Charge screening and magnetic anisotropy in RCo5 compounds,"An analysis of magnetic anisotropy in RCo5 compounds is performed with
+account of screening of ion point charges by conduction electrons. A crucial
+role of non-uniform distribution of screening electrons (the terms containing
+derivatives of charge density) is demonstrated. Influence of anisotropy of
+screening, that is connected with the anisotropy of the Fermi surface, on the
+magnetic anisotropy sign is discussed.",9811004v1
+2008-06-03,A Theoretical Approach for Computing Magnetic Anisotropy in Single Molecule Magnets,"We present a theoretical approach to calculate the molecular magnetic
+anisotropy parameters, $D_M$ and $E_M$ for single molecule magnets in any
+eigenstate of the exchange Hamiltonian, treating the anisotropy Hamiltonian as
+a perturbation. Neglecting inter-site dipolar interactions, we calculate
+molecular magnetic anisotropy in a given total spin state from the known
+single-ion anisotropies of the transition metal centers. The method is applied
+to $Mn_{12}Ac$ and $Fe_8$ in their ground and first few excited eigenstates, as
+an illustration. We have also studied the effect of orientation of local
+anisotropies on the molecular anisotropy in various eigenstates of the exchange
+Hamiltonian. We find that, in case of $Mn_{12}Ac$, the molecular anisotropy
+depends strongly on the orientation of the local anisotropies and the spin of
+the state. The $D_M$ value of $Mn_{12}Ac$ is almost independent of the
+orientation of the local anisotropy of the core $Mn(IV)$ ions. In the case of
+$Fe_8$, the dependence of molecular anisotropy on the spin of the state in
+question is weaker.",0806.0432v1
+2000-07-14,Determination of Azimuthal Anisotropy of Neutral Pions from the Measured Anisotropy of Photons in Ultra-relativistic Nuclear Collisions,"A method is suggested to deduce the anisotropy in neutral pions by measuring
+the azimuthal anisotropy of photons in ultra-relativistic nuclear collisions.
+The ratio of the estimated anisotropy in photons to the anisotropy in neutral
+pions is seen to scale with a parameter which depends on photon multiplicity
+and anisotropy. This parameter can be determined from experimental data.",0007016v1
+2014-10-16,Anisotropy of Weakly Vibrated Granular Flows,"We experimentally probe the anisotropy of the fabric of weakly vibrated,
+flowing granular media. Depending on the driving parameters --- flow rate and
+vibration strength --- this anisotropy varies significantly. We show how the
+anisotropy collapses when plotted as function of the driving stresses,
+uncovering a direct link between stresses and anisotropy. Moreover, our data
+suggests that for small anisotropies, the shear stresses vanish. Anisotropy of
+the fabric of granular media thus plays a crucial role in determining the
+rheology of granular flows.",1410.4335v1
+2016-07-17,Magnetic anisotropy dependence of the energy of oriented thick ferromagnetic films,"Heisenberg Hamiltonian was employed to describe the variation of energy of
+thick ferromagnetic films with second and fourth order anisotropies. At angle
+of 1.36 degrees and anisotropies of 1.25, energy is minimum for thick film of
+sc(001) with 1000 layers. Energy becomes minimum at angle of 1.18 degrees and
+fourth order anisotropy of 1.15 for thick film of bcc(001) with the same
+thickness. According to these simulations, these lattices can be easily
+oriented in some certain directions under the influence of some particular
+values of anisotropies. Energy varies with second and fourth order anisotropies
+in similar passion for both types of lattices. The energy gradually decreases
+with second and fourth order anisotropy for both types of lattices in the range
+described here.",1611.02227v1
+2021-07-26,Anisotropy of localized states in an anisotropic disordered medium,"We study Anderson localization of a scalar wave in an ensemble of resonant
+point scatterers embedded in an anisotropic background medium. For uniaxial
+anisotropy of moderate strength, the mobility edges and the critical exponent
+of the localization transition are found to be unaffected by the anisotropy
+provided that the determinant of the anisotropy tensor is kept equal to one
+upon introducing the anisotropy. Localized modes have anisotropic spatial
+shapes although their anisotropy is weaker than the one expected from purely
+geometric considerations. The modes with the longest lifetimes are found to be
+the most anisotropic and their anisotropy increases with the size of the
+disordered medium.",2107.12199v1
+2016-09-09,On the origin of perpendicular magnetic anisotropy in strained Fe-Co(-X) films,"Very high magnetic anisotropies have been theoretically predicted for
+strained Fe-Co(-X) and indeed several experiments on epitaxial thin films
+seemed to confirm strain induced anisotropy enhancement. This study presents a
+critical analysis of the different contributions to perpendicular anisotropy:
+volume, interface and surface anisotropies. Tracing these contributions,
+thickness series of single layer films as well as multilayers with Au-Cu
+buffers/interlayers of different lattice parameters have been prepared. The
+analysis of their magnetic anisotropy reveals a negligible influence of the
+lattice parameter of the buffer. Electronic effects, originating from both, the
+Au-Cu interface and the film surface, outrange the elastic effects. Surface
+anisotropy, however, exceeds the interface anisotropy by more than a factor of
+three. A comparison with results from Density Functional Theory suggests, that
+the experimentally observed strong perpendicular surface anisotropy originates
+from a deviation from an ideal oxide-free surface. Accordingly, tailored
+Fe-Co-X/oxide interfaces may open a route towards high anisotropy in rare-earth
+free materials.",1609.02903v2
+2016-07-17,Thick ferromagnetic films and their anisotropies as described by second order perturbed Heisenberg Hamiltonian,"Second and fourth order anisotropy dependence of energy of thick simple cubic
+ferromagnetic films with 10000 layers is explained using Heisenberg Hamiltonian
+with second order perturbation in this manuscript. The second and fourth order
+anisotropy constants were assumed to be constants through out the film. When
+the fourth order anisotropy is given by fourth order anisotropy of 6, the
+sc(001) ferromagnetic thick films with 10000 layers can be easily oriented in
+0.6 radians direction for the energy parameters given this report. Under the
+influence of the second order anisotropy given by second order anisotropy of
+6.3, the easy direction of sc(001) film with 10000 layers is given by 0.66
+radians. Although the energy varies periodically in all cases, the maximum
+energy considerably decreases with fourth order anisotropy constant. According
+to 3-D plots, energy under influence of second order anisotropy is larger than
+energy under influence of fourth order anisotropy.",1611.02228v1
+2018-07-10,Modeling Molecular Magnets with Large Exchange and On-Site Anisotropies,"Spins in molecular magnets can experience both anisotropic exchange
+interactions and on-site magnetic anisotropy. In this paper we study the effect
+of exchange anisotropy on the molecular magnetic anisotropy both with and
+without on-site anisotropy. When both the anisotropies are small, we find that
+the axial anisotropy parameter $D_M$ in the effective spin Hamiltonian is the
+sum of the individual contributions due to exchange and on-site anisotropies.
+We find that even for axial anisotropy of about $15\%$, the low energy spectrum
+does not correspond to a single parent spin manifold but has intruders states
+arising from other parent spin. In this case, the low energy spectrum can not
+be described by an effective Hamiltonian spanning the parent spin space. We
+study the magnetic susceptibility, specific heat as a function of temperature
+and magnetization as a function of applied field to characterize the system in
+this limit. We find that there is synergy between the two anisotropies,
+particularly for large systems with higher site spins.",1807.03500v1
+2023-12-21,Effects of Heliolatitudinal Anisotropy of Solar FUV/EUV Emissions on Lyman-alpha Helioglow,"We present a study of the influence of solar UV anisotropy on the
+heliospheric backscatter helioglow generated by resonant scattering of solar
+Lyman-alpha photons on interstellar hydrogen atoms around the Sun. Simulations
+based on the WawHelioGlow model suggest that the response of the helioglow
+pole-to-ecliptic ratio to the anisotropy is linear, but 15% of the anisotropy
+(polar darkening) generates 30-40% change in the ratio in the solar minimum and
+15-20% in the solar maximum. We attribute this difference to an interplay
+between the solar UV anisotropy and the latitudinal structure of the solar wind
+in solar minima. The solar UV anisotropy also increases the helioglow intensity
+from the downwind direction by 5-10%, due to the influence of the anisotropy on
+the ionization losses and trajectories of atoms passing by the Sun in polar
+regions. Consequently, mid-latitude regions (in the heliographic and ecliptic
+coordinates) are least affected by the UV anisotropy. By comparison of the
+simulation results with observations of the SOHO/SWAN satellite instrument, we
+derive the day-by-day time evolution of the solar Lyman-alpha anisotropy for
+the north and south poles over two solar cycles from 1996 to 2022. The inferred
+anisotropy is ~5-10% in solar minima and ~15-25% in solar maxima, the northern
+anisotropy being stronger than the southern. Our study suggests that in solar
+minima a highly structured solar wind is associated with relatively small solar
+UV anisotropy, while in solar maxima the solar wind is more isotropic but a
+substantial solar UV anisotropy appears.",2312.14039v1
+2006-01-25,Primordial magnetic fields and CMB anisotropies,"Possible signatures of primordial magnetic fields on the Cosmic Microwave
+Background (CMB) temperature and polarization anisotropies are reviewed. The
+signals that could be searched for include excess temperature anisotropies
+particularly at small angular scales below the Silk damping scale, B-mode
+polarization, and non-Gaussian statistics. A field at a few nG level produces
+temperature anisotropies at the 5 micro Kelvin level, and B-mode polarization
+anisotropies 10 times smaller, and is therefore potentially detectable via the
+CMB anisotropies. An even smaller field, with B_0 < 0.1 nG, could lead to
+structure formation at high redshift z > 15, and hence naturally explain an
+early re-ionization of the Universe.",0601570v1
+2004-03-01,The anisotropy of granular materials,"The effect of the anisotropy on the elastoplastic response of two dimensional
+packed samples of polygons is investigated here, using molecular dynamics
+simulation. We show a correlation between fabric coefficients, characterizing
+the anisotropy of the granular skeleton, and the anisotropy of the elastic
+response. We also study the anisotropy induced by shearing on the subnetwork of
+the sliding contacts. This anisotropy provides an explanation to some features
+of the plastic deformation of granular media.",0403064v1
+2004-12-17,Mesoscopic bound on anisotropy in itinerant ferromagnets,"We calculate the anisotropy energy of a single-domain ferromagnetic particle
+in which the only source of anisotropy is the presence of non-magnetic
+impurities. We find that such anisotropy takes the form of combined easy-axis
+and easy-plane anisotropies, with random orientations of the axes. Typically
+the anisotropy energy is of order $N^{1/2} \hbar/tau_{so}$, where $N$ is the
+number of electrons in the ferromagnetic particle and $\tau_{so}$ is the
+spin-orbit time.",0412488v1
+2012-05-03,Anisotropy tuning with the Wilson flow,"We use the Wilson flow to define the gauge anisotropy at a given physical
+scale. We demonstrate the use of the anisotropic flow by performing the tuning
+of the bare gauge anisotropy in the tree-level Symanzik action for several
+lattice spacings and target anisotropies. We use this method to tune the
+anisotropy parameters in full QCD, where we also exploit the diminishing effect
+of a well chosen smearing on the renormalization of the fermion anisotropy.",1205.0781v1
+2012-11-19,Magnetic anisotropy of La0.7Sr0.3MnO3 nanopowders,"The magnetic anisotropy of La0.7Sr0.3MnO3 nanopowders was measured as a
+function of temperature by the modified singular point detection technique. In
+this method singularities indicating the anisotropy field were determined
+analyzing ac susceptibility data. The observed relationship between temperature
+dependence of anisotropy constant and temperature dependence of magnetization
+was used to deduce the origin of magnetic anisotropy in the nanopowders. It was
+shown that magnetic anisotropy of La0.7Sr0.3MnO3 nanopowder is determined by
+two-ion (dipolar or pseudodipolar) and single-ion mechanisms.",1211.4355v1
+2015-11-16,Transport anisotropy in Ge quantum wells in the absence of quantum oscillations,"Recent study of a high-mobility 2D hole gas in a strained Ge quantum well
+revealed strong transport anisotropy in the quantum Hall regime when the
+magnetic field was tilted away from the sample normal. In the present study we
+demonstrate that the anisotropy persists to such high temperatures and filling
+factors that quantum oscillations are no longer observed. This finding rules
+out the formation of a stripe phase as a possible origin for the observed
+anisotropy. However, we also show that the observed anisotropy is not
+consistent with other known anisotropies, such as those arising from finite
+thickness effects or surface roughness.",1511.05168v1
+2017-11-08,Effective uniaxial anisotropy in easy-plane materials through nanostructuring,"Permanent magnet materials require a high uniaxial magneto-crystalline
+anisotropy. Exchange coupling between small crystallites with easy-plane
+anisotropy induces an effective uniaxial anisotropy if arranged accordingly.
+Nanostructuring of materials with easy-plane anisotropy is an alternative way
+to create hard-magnetic materials. The coercivity increases with decreasing
+feature size. The resulting coercive field is about 12 percent of the
+anisotropy field for a crystal size of 3.4 times the Bloch parameter.",1711.03144v1
+2023-04-08,Integral Absorption of Microwave Power by Random-Anisotropy Magnets,"We study analytically and numerically on lattices containing $10^5$ spins,
+the integral absorption of microwaves by a random-anisotropy magnet, $\int
+d\omega P(\omega)$. It scales as $D^2_R/J$ on the random-anisotropy strength
+$D_R$ and the strength of the ferromagnetic exchange $J$ in low-anisotropy
+amorphous magnetic materials. At high anisotropy and in low-anisotropy
+materials sintered of sufficiently large ferromagnetic grains, the integral
+power scales linearly on $D_R$. The maximum bandwidth, combined with the
+maximum absorption power, is achieved when the amorphous structure factor, or
+grain size, is of an order of the domain wall thickness in a conventional
+ferromagnet that is of the order of $(J/D_R)^{1/2}$ lattice spacings.",2304.04121v1
+2010-02-02,"Magnetic anisotropy of epitaxial (Ga,Mn)As on (113)A GaAs","The temperature dependence of magnetic anisotropy in (113)A (Ga,Mn)As layers
+grown by molecular beam epitaxy is studied by means of superconducting quantum
+interference device (SQUID) magnetometry as well as by ferromagnetic resonance
+(FMR) and magnetooptical effects. Experimental results are described
+considering cubic and two kinds of uniaxial magnetic anisotropy. The magnitude
+of cubic and uniaxial anisotropy constants is found to be proportional to the
+fourth and second power of saturation magnetization, respectively. Similarly to
+the case of (001) samples, the spin reorientation transition from uniaxial
+anisotropy with the easy along the [-1, 1, 0] direction at high temperatures to
+the biaxial <100> anisotropy at low temperatures is observed around 25 K. The
+determined values of the anisotropy constants have been confirmed by FMR
+studies. As evidenced by investigations of the polar magnetooptical Kerr
+effect, the particular combination of magnetic anisotropies allows the
+out-of-plane component of magnetization to be reversed by an in-plane magnetic
+field. Theoretical calculations within the p-d Zener model explain the
+magnitude of the out-of-plane uniaxial anisotropy constant caused by epitaxial
+strain, but do not explain satisfactorily the cubic anisotropy constant. At the
+same time the findings point to the presence of an additional uniaxial
+anisotropy of unknown origin. Similarly to the case of (001) films, this
+additional anisotropy can be explained by assuming the existence of a shear
+strain. However, in contrast to the (001) samples, this additional strain has
+an out-of-the-(001)-plane character.",1002.0563v2
+2020-01-28,Intrinsic Anisotropy and Pinning Anisotropy in Nanostructured YBa$_2$Cu$_3$O$_{7-δ}$ from Microwave Measurements,"Anisotropy is an intrinsic factor that dictates the magnetic properties of
+YBCO, thus with great impact for many applications. Artificial pinning centres
+are often introduced in an attempt to mitigate its effect, resulting in less
+anisotropic electrical and magnetic properties. However, the nanoengineering of
+the superconductor makes the quantification of the anisotropy itself uncertain:
+the intrinsic anisotropy due to the layered structure, quantified by the
+anisotropy factor $\gamma$, mixes up with the additional anisotropy due to
+pinning. As a consequence, there is no consensus on the experimental anisotropy
+factor $\gamma$ that can result in YBCO when directional (twin planes,
+nanorods) or isotropic defects are present. We present here measurements of the
+magnetic field and angular dependent surface impedance in very different
+nanostructured YBCO films, grown by chemical route and by pulsed laser
+deposition, with different kind of defects (nanorods, twin planes,
+nanoparticles). We show that the surface impedance measurements are able to
+disentangle the intrinsic anisotropy from the directional pinning anisotropy,
+thanks to the possibility to extract the true anisotropic flux--flow
+resistivity and by correctly exploiting the angular scaling. We find in all
+films that the intrinsic anisotropy $\gamma = 5.3\pm0.7$. By contrast, the
+pinning anisotropy determines a much complex, feature--rich and nonuniversal,
+sample--dependent angular landscape.",2001.10299v1
+2020-04-02,Contrast-to-noise ratio analysis of microscopic diffusion anisotropy indices in q-space trajectory imaging,"Diffusion anisotropy in diffusion tensor imaging (DTI) is commonly quantified
+with normalized diffusion anisotropy indices (DAIs). Most often, the fractional
+anisotropy (FA) is used, but several alternative DAIs have been introduced in
+attempts to maximize the contrast-to-noise ratio (CNR) in diffusion anisotropy
+maps. Examples include the scaled relative anisotropy (sRA), the gamma variate
+anisotropy index (GV), the surface anisotropy (UAsurf), and the lattice index
+(LI). With the advent of multidimensional diffusion encoding it became possible
+to determine the presence of microscopic diffusion anisotropy in a voxel, which
+is theoretically independent of orientation coherence. In accordance with DTI,
+the microscopic anisotropy is typically quantified by the microscopic
+fractional anisotropy (uFA). In this work, in addition to the uFA, the four
+microscopic diffusion anisotropy indices (uDAIs) usRA, uGV, uUAsurf, and uLI
+are defined in analogy to the respective DAIs by means of the average diffusion
+tensor and the covariance tensor. Simulations with three representative
+distributions of microscopic diffusion tensors revealed distinct CNR
+differences when differentiating between isotropic and microscopically
+anisotropic diffusion. q-Space trajectory imaging (QTI) was employed to acquire
+brain in-vivo maps of all indices. For this purpose, a 15 min protocol
+featuring linear, planar, and spherical tensor encoding was used. The resulting
+maps were of good quality and exhibited different contrasts, e.g. between gray
+and white matter. This indicates that it may be beneficial to use more than one
+uDAI in future investigational studies.",2004.00892v1
+1997-05-03,Evolution of Tidally Truncated Globular Clusters with Anisotropy,"The evolution of tidally truncated globular clusters is investigated by
+integrating two-dimensional Fokker-Planck equation that allows the development
+of velocity anisotropy. We start from the isotropic Plummer model with tidal
+cut off and followed the evolution through the corecollapse. The heating by
+three-binary is included to obtain the evolution past the corecollapse. The
+anisotropy in velocity dispersion develops during the precollapse evolution.
+However, the anisotropy becomes highly depressed during the post-collapse
+evolution because of rapid loss of radial orbits. Maximum radial anisotropy
+appears just after the beginning of the expansion, and degree of anisotropy
+decreases slowly as the total mass of the cluster decreases. Thus it may be
+possible to determine the evolutionary status of a cluster if the velocity
+anisotropy can be measured in the sense that the postcollapse clusters always
+have very little degree of anisotropy. The structure of the post-collapse
+cluster can be well fitted to King models because the degree of anisotropy is
+rather small.",9705012v1
+2006-01-14,Cosmic Microwave Background Mini-Review,"A compact overview of the status of CMB anisotropy results and their
+cosmological interpretation up until the end of 2005. Sections headings:
+Introduction; Description of CMB Anisotropies; Cosmological Parameters; Physics
+of Anisotropies; Current Anisotropy Data; CMB Polarization; Complications;
+Constraints on Cosmologies; Particle Physics Constraints; Fundamental Lessons;
+and Future Directions.",0601307v1
+2003-11-13,Penetration depth anisotropy in two-band superconductors,"The anisotropy of the London penetration depth is evaluated for two-band
+superconductors with arbitrary inter- and intra-band scattering times. If one
+of the bands is clean and the other is dirty in the absence of inter-band
+scattering, the anisotropy is dominated by the Fermi surface of the clean band
+and is weakly temperature dependent. The inter-band scattering also suppress
+the temperature dependence of the anisotropy.",0311331v1
+2006-02-16,Ferromagnetic resonance in systems with competing uniaxial and cubic anisotropies,"We develop a model for ferromagnetic resonance in systems with competing
+uniaxial and cubic anisotropies. This model applies to (i) magnetic materials
+with both uniaxial and cubic anisotropies, and (ii) magnetic nanoparticles with
+effective core and surface anisotropies; We numerically compute the resonance
+frequency as a function of the field and the resonance field as a function of
+the direction of the applied field for an arbitrary ratio of cubic-to-uniaxial
+anisotropy. We also provide some approximate analytical expressions in the case
+of weak cubic anisotropy. We propose a method that uses these expressions for
+estimating the uniaxial and cubic anisotropy constants, and for determining the
+relative orientation of the cubic anisotropy axes with respect to the crystal
+principle axes. This method is applicable to the analysis of experimental data
+of resonance type measurements for which we give a worked example of an iron
+thin film with mixed anisotropy.",0602369v3
+2010-01-11,The influence of weak texture on the critical currents in polycrystalline MgB$_2$,"The current transport in polycrystalline MgB$_2$ is strongly influenced by
+the intrinsic anisotropy of this superconductor. Untextured bulks and wires are
+macroscopically isotropic, but the grains retain their anisotropic properties
+and the field dependence of the critical currents is much stronger than in
+isotropic superconductors. Weakly or partially textured tapes are
+macroscopically anisotropic, but the anisotropy of the zero resistivity (or
+irreversibility) field is smaller than the intrinsic upper critical field
+anisotropy, $\gamma$. The \Jc-anisotropy is field and temperature dependent and
+can be much larger than $\gamma$. The most suitable parameter for the
+quantification of the macroscopic anisotropy is, therefore, the anisotropy of
+the zero resistivity field. It is difficult to distinguish between a higher
+degree of texture at a lower intrinsic anisotropy and a weaker texture at
+higher anisotropy and hardly possible based on the field dependence of the
+critical current anisotropy alone. The knowledge of the upper critical field is
+crucial and angular resolved measurements of either the critical currents or,
+better, the resistive in-field transitions are favorable for this purpose.",1001.1678v1
+2010-03-09,Effect of induced shape anisotropy on magnetic properties of ferromagnetic cobalt nanocubes,"We report on the synthesis of ferromagnetic cobalt nanocubes of various sizes
+using thermal pyrolysis method and the effect of shape anisotropy on the static
+and dynamic magnetic properties were studied. Shape anisotropy of approximately
+10 % was introduced in nanocubes by making nanodiscs using a linear chain amine
+surfactant during synthesis process. It has been observed that, ferromagnetism
+persisted above room temperature and a sharp drop in magnetic moment at low
+temperatures in zero-field cooled magnetization may be associated with the spin
+disorder due to the effective anisotropy present in the system. Dynamic
+magnetic properties were studied using RF transverse susceptibility
+measurements at different temperatures and the singularities due to anisotropy
+fields were probed at low temperatures. Symmetrically located broad peaks are
+observed in the frozen state at the effective anisotropy fields and the peak
+structure is strongly affected by shape anisotropy and temperature.
+Irrespective of size the shape anisotropy gave rise to higher coercive fields
+and larger transverse susceptibility ratio at all temperatures. The role of
+shape anisotropy and the size of the particles on the observed magnetic
+behaviour were discussed.",1003.1855v1
+2019-02-19,Magnetic interaction and anisotropy axes arrangement in nanoparticle aggregates can enhance or reduce the effective magnetic anisotropy,"The magnetic response of nanostructures plays an important role on biomedical
+applications being strongly influenced by the magnetic anisotropy. In this work
+we investigate the role of temperature, particle concentration and nanoparticle
+arrangement forming aggregates in the effective magnetic anisotropy of Mn-Zn
+ferrite-based nanoparticles. Electron magnetic resonance and coercivity
+temperature dependence analyses, were critically compared for the estimation of
+the anisotropy. We found that the temperature dependence of the anisotropy
+follows the Callen-Callen model, while the symmetry depends on the particle
+concentration. At low concentration one observes only an uniaxial term, while
+increasing a cubic contribution has to be added. The effective anisotropy was
+found to increase the higher the particle concentration on magnetic colloids,
+as long as the easy axis was at the same direction of the nanoparticle chain.
+Increasing even further the concentration up to a highly packed condition
+(powder sample) one observes a decrease of the anisotropy, that was attributed
+to the random anisotropy axes configuration.",1902.07188v1
+2022-02-25,Skyrmion crystals in centrosymmetric triangular magnets under hexagonal and trigonal single-ion anisotropy,"We theoretically report an instability toward a skyrmion crystal in
+centrosymmetric magnets under hexagonal and trigonal single-ion anisotropy. The
+results are obtained for a minimal spin model with a crystal-dependent
+single-ion anisotropy on a triangular lattice by performing simulated
+annealing. By constructing magnetic phase diagrams in the presence of six
+different types of single-ion anisotropy while changing the amplitudes of
+external magnetic field and single-ion anisotropy in a systematic way, we find
+that the hexagonal and trigonal single-ion anisotropy becomes a source of the
+skyrmion crystal depending on the magnetic-field direction. We show that the
+skyrmion crystal is stabilized by the uniaxial-type or trigonal-type single-ion
+anisotropy under the out-of-plane magnetic field, while it is stabilized by the
+hexagonal-type inplane single-ion anisotropy under the inplane magnetic field.
+We also find various multiple-$Q$ spin states depending on the types of the
+single-ion anisotropy.",2202.12964v1
+2014-02-05,Numerical micromagnetism of strong inhomogeneities,"The size of micromagnetic structures, such as domain walls or vortices, is
+comparable to the exchange length of the ferromagnet. Both, the exchange length
+of the stray field $l_s$ and the magnetocrystalline exchange length $l_k$ are
+material-dependent quantities that usually lie in the nanometer range. This
+emphasizes the theoretical challenges associated with the mesoscopic nature of
+micromagnetism: the magnetic structures are much larger than the atomic lattice
+constant, but at the same time much smaller than the sample size. In computer
+simulations, the smallest exchange length serves as an estimate for the largest
+cell size admissible to prevent appreciable discretization errors. This general
+rule is not valid in special situations where the magnetization becomes
+particularly inhomogeneous. When such strongly inhomogeneous structures
+develop, micromagnetic simulations inevitably contain systematic and numerical
+errors. It is suggested to combine micromagnetic theory with a Heisenberg model
+to resolve such problems. We analyze cases where strongly inhomogeneous
+structures pose limits to standard micromagnetic simulations, arising from
+fundamental aspects as well as from numerical drawbacks.",1402.1142v1
+2015-07-30,Manipulating Magnetism at Organic/Ferromagnetic Interfaces by Fullerene-Induced Surface Reconstruction,"Fullerenes have several advantages as potential materials for organic
+spintronics. Through a theoretical first-principles study, we report that
+fullerene C$_{60}$ adsorption can induce a magnetic reconstruction in a Ni(111)
+surface and expose the merits of the reconstructed C$_{60}$/Ni(111)
+\emph{spinterface} for molecular spintronics applications. Surface
+reconstruction drastically modifies the magnetic properties at both sides of
+the C$_{60}$/Ni interface. Three outstanding properties of the reconstructed
+structure are revealed, which originate from reconstruction enhanced spin-split
+$\mathrm{\pi}$$-$d coupling between C$_{60}$ and Ni(111): 1) the C$_{60}$ spin
+polarization and conductance around the Fermi level are enhanced
+simultaneously, which can be important for read-head sensor miniaturization; 2)
+localized spin-polarized states appear in C$_{60}$ with a spin-filter
+functionality, and 3) magnetocrystalline anisotropic energy and exchange
+coupling in the outermost Ni layer are reduced enormously. Surface
+reconstruction can be realized simply by controlling the annealing temperature
+in experiments.",1507.08378v1
+2017-01-09,Six-fold crystalline anisotropic magnetoresistance in the (111) LaAlO$_3$/SrTiO$_3$ oxide interface,"We measured the magnetoresistance of the 2D electron liquid formed at the
+(111) LaAlO$_3$/SrTiO$_3$ interface. The hexagonal symmetry of the interface is
+manifested in a six-fold crystalline component appearing in the anisotropic
+magnetoresistance (AMR) and planar Hall data, which agree well with symmetry
+analysis we performed. The six-fold component increases with carrier
+concentration, reaching 15% of the total AMR signal. Our results suggest the
+coupling between higher itinerant electronic bands and the crystal as the
+origin of this effect and demonstrate that the (111) oxide interface is a
+unique hexagonal system with tunable magnetocrystalline effects.",1701.02153v2
+2017-03-24,Intrinsic ferromagnetism and quantum anomalous Hall effect in CoBr2 monolayer,"The electronic, magnetic, and topological properties of CoBr2 monolayer are
+studied in the frame-work of the density-functional theory (DFT) combined with
+tight-binding (TB) modeling in terms of Wannier basis. Our DFT investigation
+and Monte Carlo simulation show that there exists intrinsic two-dimensional
+ferromagnetism in the CoBr2 monolayer thanks to large out-of-plane
+magnetocrystalline anisotropic energy. Our further study shows that the
+spin-orbits coupling makes it become a topologically nontrivial insulator with
+quantum anomalous Hall effect and topological Chern number C=4, and its edge
+states can be manipulated by changing the width of its nanoribbons and applying
+strains. The CoBr2 monolayer can be exfoliated from the layered CoBr2 bulk
+material because its exfoliation energy is between those of graphene and MoS2
+monolayer and it is dynamically stable. These results make us believe that the
+CoBr2 monolayer can make a promising spintronic material for future
+high-performance devices.",1703.08565v2
+2019-09-13,Fully spin-polarized quadratic non-Dirac bands realized quantum anomalous Hall effect,"The quantum anomalous Hall effect is a intriguing quantum state which
+exhibits the chiral edge states in the absence of magnetic field. While the
+search for quantum anomalous Hall insulators is still active, the researchers
+mainly search for the systems containing magnetic atom. Here, based on
+first-principles density functional theory, we predict a new family of chern
+insulators with fully spin-polarized quadratic px;y non-Dirac bands in the
+alkali earth metal BaX (X = Si, Ge, Sn) system. We show that BaX monolayer has
+a half-metallic ferromagnetic ground state. The ferromagnetism is mainly
+originated from the p orbitals of Si, Ge and Sn atoms. The 2D BaSn monolayer
+exhibits a large magnetocrystalline anisotropic energy of 12.20 meV/cell and a
+nontrivial band gap of 159.10 meV. Interestingly, both the spin polarization of
+the chiral edge currents and the sign of Chern number can be tuned by doping.
+Furthermore, the 4 % compressive strain can drive structural phase transition
+but the nontrivial topological properties remain reserve in the 2D BaX systems.
+Our findings not only extend the novel concepts but also provide fascinating
+opportunities for the realization of quantum anomalous Hall effect
+experimentally.",1909.06071v2
+2020-01-24,Anisotropic magnetoresistance in spin-orbit semimetal SrIrO3,"SrIrO3, the three-dimensional member of the Ruddlesden-Popper iridates, is a
+paramagnetic semimetal characterised by a the delicate interplay between
+spin-orbit coupling and Coulomb repulsion. In this work, we study the
+anisotropic magnetoresistance (AMR) of SrIrO3 thin films, which is closely
+linked to spin-orbit coupling and probes correlations between electronic
+transport, magnetic order and orbital states. We show that the low-temperature
+negative magnetoresistance is anisotropic with respect to the magnetic field
+orientation, and its angular dependence reveals the appearance of a fourfold
+symmetric component above a critical magnetic field. We show that this AMR
+component is of magnetocrystalline origin, and attribute the observed
+transition to a field-induced magnetic state in SrIrO3.",2001.08939v1
+2022-12-22,Magnetoelasticity-driven phase inversion of ultrafast spin precession in NixFe100-x thin films,"We present strong evidences for the deterministic role of magnetoelasticity
+in ultrafast spin dynamics of ferromagnetic NixFe100-x alloy films. Without a
+change in the crystal structure, we observed sudden Pi-phase inversion of the
+spin precession in the range of x = 87.0 - 97.5. In addition, it was found that
+the phase was continuously changed and reversed its sign by varying the pump
+fluence. These cannot be explained simply by temperature dependence of
+magnetocrystalline, demagnetizing, and Zeeman fields which have been
+conventionally considered so far in describing the spin dynamics. Through the
+temperature- and composition-dependent simulations adding the magnetoelastic
+field generated from the lattice thermal strain, we revealed that the
+conventional and magnetoelastic fields were competing around x = 95.3, where
+the spin dynamics showed the largest phase shift. For analytic understanding,
+we further show that the temperature-dependent interplay of the Curie
+temperature, saturation magnetization, and magnetostriction, which are
+demonstrated to be the most important macroscopic parameters, determines the
+ultrafast spin dynamics. Our extensive study emphasizes that magnetoelasticity
+is the key ingredient for fully understanding the driving mechanism of
+ultrafast spin dynamics.",2212.11852v1
+2023-11-27,Coherent control of photomagnetic back-switching by double-pump laser pulses,"The control of nonthermal, all-optical magnetization switching under the
+regime with an independent state of laser polarization opens up new
+opportunities for ultrafast magnetic recording. Here, we investigate the
+photo-magnetic back-switching capabilities of the write and erase magnetic
+domain pattern using double-pump pulse excitations in an iron garnet film with
+pure cubic magnetocrystalline symmetry. It is essential to note that forward
+and backward magnetization switching is achievable in two distinctive
+scenarios: using identical linearly polarized laser pulses and with pulses
+having orthogonal polarization planes. By observing the switch of magnetization
+at domains independent of the initial state, one can nonthermally toggle the
+magnetization, equivalent to XOR logical operation, at frequencies reaching up
+to 50 GHz.",2311.16336v2
+2023-09-19,Probing the spatial and velocity anisotropies in stellar halos from the Aquarius simulations,"We analyze the spatial anisotropy and the velocity anisotropy in a set of
+mock stellar halos from the Aquarius simulations. The spatial anisotropy in
+each mock stellar halo rises progressively with the increasing distance from
+the halo centre, eventually reaching a maximum near the periphery. Excluding
+the bound satellites leads to a significant reduction of the spatial anisotropy
+in each halo. We compare the measured anisotropy in the mock stellar halos with
+that from their sphericalized versions where all the shape and substructure
+induced anisotropies are erased. The growth of spatial anisotropy persists
+throughout the entire halo when the bound satellites are present but remains
+limited within the inner halo ($<60 \, h^{-1}\, {\rm kpc}$) after their
+exclusion. This indicates that the spatial anisotropy in the inner halo is
+induced by the diffuse substructures and the halo shape whereas the outer halo
+anisotropy is dominated by the bound satellites. We find that the outer parts
+of the stellar halo are kinematically colder than the inner regions. The
+stellar orbits are predominantly radial but they become rotationally dominated
+at certain radii that are marked by the prominent $\beta$ dips. Most of the
+$\beta$ dips disappear after the removal of the satellites. A few shallow and
+broad $\beta$ dips arise occasionally due to the presence of diffuse streams
+and clouds. Our analysis suggests that a combined study of the spatial and
+velocity anisotropies can reveal the structure and the assembly history of the
+stellar halos.",2309.10798v1
+1995-07-06,Galaxy clusters and microwave background anisotropy,"Previous estimates of the microwave background anisotropies produced by
+freely falling spherical clusters are discussed. These estimates are based on
+the Swiss-Cheese and Tolman-Bondi models. It is proved that these models give
+only upper limits to the anisotropies produced by the observed galaxy clusters.
+By using spherically symmetric codes including pressureless matter and a hot
+baryonic gas, new upper limits are obtained. The contributions of the hot gas
+and the pressureless component to the total anisotropy are compared. The
+effects produced by the pressure are proved to be negligible; hence,
+estimations of the cluster anisotropies based on N-body simulations are
+hereafter justified. After the phenomenon of violent relaxation, any realistic
+rich cluster can only produce small anisotropies with amplitudes of order
+$10^{-7}$. During the rapid process of violent relaxation, the anisotropies
+produced by nonlinear clusters are expected to range in the interval
+$(10^{-6},10^{-5})$. The angular scales of these anisotropies are discussed.",9507019v2
+1996-03-01,DT/T beyond linear theory,"The major contribution to the anisotropy of the temperature of the Cosmic
+Microwave Background (CMB) radiation is believed to come from the interaction
+of linear density perturbations with the radiation previous to the decoupling
+time. Assuming a standard thermal history for the gas after recombination, only
+the gravitational field produced by the linear density perturbations present on
+a $\Omega\neq 1$ universe can generate anisotropies at low z (these
+anisotropies would manifest on large angular scales). However, secondary
+anisotropies are inevitably produced during the nonlinear evolution of matter
+at late times even in a universe with a standard thermal history. Two effects
+associated to this nonlinear phase can give rise to new anisotropies: the
+time-varying gravitational potential of nonlinear structures (Rees-Sciama RS
+effect) and the inverse Compton scattering of the microwave photons with hot
+electrons in clusters of galaxies (Sunyaev-Zeldovich SZ effect). These two
+effects can produce distinct imprints on the CMB temperature anisotropy. We
+discuss the amplitude of the anisotropies expected and the relevant angular
+scales in different cosmological scenarios. Future sensitive experiments will
+be able to probe the CMB anisotropies beyong the first order primary
+contribution.",9603001v1
+1997-07-29,Spin-Orbit-Induced Magnetic Anisotropy for Impurities in Metallic Samples I. Surface Anisotropy,"Motivated by the recent measurements of Kondo resistivity in thin films and
+wires, where the Kondo amplitude is suppressed for thinner samples, the surface
+anisotropy for magnetic impurities is studied. That anisotropy is developed in
+those cases where in addition to the exchange interaction with the impurity
+there is strong spin-orbit interaction for conduction electrons around the
+impurity in the ballistic region. The asymmetry in the neighborhood of the
+magnetic impurity exhibits the anisotropy axis $n$ which, in the case of a
+plane surface, is perpendicular to the surface. The anisotropy energy is
+$\Delta E=K_d (nS)^2$ for spin $S$, and the anisotropy constant $K_d$ is
+inversionally proportional to distance $d$ measured from the surface and
+$K_d>0$. Thus at low temperature the spin is frozen in a singlet or doublet of
+lowest energy. The influence of that anisotropy on the electrical resistivity
+is the subject of the following paper (part II).",9707298v1
+2001-02-28,In-plane upper critical field anisotropy in Sr2RuO4 and CeIrIn5,"Experiments on tetragonal Sr2RuO4 and CeIrIn5 indicate the presence of
+superconductivity with a multi-component superconducting order parameter. Such
+an order parameter should exhibit an in-plane anisotropy in the upper critical
+field near the superconducting transition temperature that does not occur for
+single-component superconductors. Here, this anisotropy is determined from
+microscopic calculations for arbitrary gap functions. It is shown that this
+anisotropy is generally not small and, in some cases, independent of impurity
+scattering. Furthermore, this anisotropy is calculated for many detailed
+microscopic models of Sr2RuO4. For these models this anisotropy is found to be
+large, which is in sharp contrast to the small anisotropy observed
+experimentally. However, an accidental cancellation of the anisotropy for gaps
+on different Fermi surface sheets can lead to a result that is consistent with
+experiment.",0102530v1
+2006-03-06,"Effect of the shape anisotropy on the magnetic configuration of (Ga,Mn)As and its evolution with temperature","We study the effect of the shape anisotropy on the magnetic domain
+configurations of a ferromagnetic semiconductor (Ga,Mn)As/GaAs(001) epitaxial
+wire as a function of temperature. Using magnetoresistance measurements, we
+deduce the magnetic configurations and estimate the relative strength of the
+shape anisotropy compared with the intrinsic anisotropies. Since the intrinsic
+anisotropy is found to show a stronger temperature dependence than the shape
+anisotropy, the effect of the shape anisotropy on the magnetic domain
+configuration is relatively enhanced with increasing temperature. This
+information about the shape anisotropy provides a practical means of designing
+nanostructured spin electronic devices using (Ga,Mn)As.",0603126v1
+2006-07-14,In-plane Anisotropy of the Magnetic Fluctuations in NaxCoO2-yH2O,"We report the $^{59}$Co NMR studies of the in-plane anisotropy of bilayer
+hydrated Na$_{x}\mathrm{CoO_{2}} \cdot$$y\mathrm{H_{2}O}$ using a oriented
+powder sample by a magnetic field in Fluorinert FC70. We found for the first
+time the $ab$-plane anisotropy of the $^{59}$Co NMR Knight shift $K$, the
+nuclear spin-lattice relaxation rate 1/$T_{1}$ and the nuclear spin-spin
+relaxation rate 1/$T_{2}$ at a magnetic field $H \sim$ 7.5 T up to 200K. Below
+75 K, the anisotropy of $K$ is large compared with that at high temperatures.
+The hyperfine coupling constants seem to change around the temperature 150 K,
+in which the bulk susceptibility $\chi$ shows broad minimum, suggesting a
+change of the electronic state of CoO$_{2}$ plane. 1/$T_{1}$ also shows a
+significant anisotropy, which cannot be explained only by the anisotropy of the
+hyperfine coupling constants nor the anisotropic uniform spin susceptibility.
+The difference in the in-plane anisotropy of $T_{1}$ from that of $K$ indicates
+that the magnetic fluctuation at a finite wave vector $\vec{q} \neq 0$ is also
+anisotropic and the anisotropy is different from that at $\vec{q} = 0$.",0607368v1
+2006-11-30,Influence of weak anisotropy on scaling regimes in a model of advected vector field,"Influence of weak uniaxial small-scale anisotropy on the stability of
+inertial-range scaling regimes in a model of a passive transverse vector field
+advected by an incompressible turbulent flow is investigated by means of the
+field theoretic renormalization group. Weak anisotropy means that parameters
+which describe anisotropy are chosen to be close to zero, therefore in all
+expressions it is enough to leave only linear terms in anisotropy parameters.
+Turbulent fluctuations of the velocity field are taken to have the Gaussian
+statistics with zero mean and defined noise with finite correlations in time.
+It is shown that stability of the inertial-range scaling regimes in the
+three-dimensional case is not destroyed by anisotropy but the corresponding
+stability of the two-dimensional system can be destroyed even by the presence
+of weak anisotropy. A borderline dimension $d_c$ below which the stability of
+the scaling regime is not present is calculated as a function of anisotropy
+parameters.",0611060v1
+2002-05-25,Flow with PMD: Past and Future,"Measurements of azimuthal distribution of inclusive photons using the fine
+granularity preshower photon multiplicity detector (PMD) at CERN SPS are used
+to obtain anisotropy in the azimuthal distributions. These results are used to
+estimate the anisotropy in the neutral pion distributions. The results are
+compared with results of charged particle data, both for first order and second
+order anisotropy. Assuming the same anisotropy for charged and neutral pions,
+the anisotropy in photons is estimated and compared with the measured
+anisotropy. The effect of neutral pion decay on the correlation between the
+first order and the second order event plane is also discussed. Data from PMD
+can also be used to estimate the reaction plane for studying any anisotropy in
+particle emission characteristics in the ALICE experiment at the Large Hadron
+Collider. In particular, we show that using the event plane from the PMD, it
+will be possible to measure the anisotropy in Jpsi absorption (if any) in the
+ALICE experiment.",0205017v1
+1997-03-05,A note on the light velocity anisotropy,"In the framework of linear transformations between inertial systems, there
+are no physical reasons for assuming any anisotropy in the one-way velocity of
+light.",9703006v1
+2007-05-11,Effective anisotropies and energy barriers of magnetic nanoparticles with Neel surface anisotropy,"Magnetic nanoparticles with Neel surface anisotropy, different internal
+structures, surface arrangements and elongation are modelled as many-spin
+systems. The results suggest that the energy of many-spin nanoparticles cut
+from cubic lattices can be represented by an effective one-spin potential
+containing uniaxial and cubic anisotropies. It is shown that the values and
+signs of the corresponding constants depend strongly on the particle's surface
+arrangement, internal structure and elongation. Particles cut from a simple
+cubic lattice have the opposite sign of the effective cubic term, as compared
+to particles cut from the face-centered cubic lattice. Furthermore, other
+remarkable phenomena are observed in nanoparticles with relatively strong
+surface effects: (i) In elongated particles surface effects can change the sign
+of the uniaxial anisotropy. (ii) In symmetric particles (spherical and
+truncated octahedral) with cubic core anisotropy surface effects can change its
+sign. We also show that the competition between the core and surface
+anisotropies leads to a new energy that contributes to both the 2nd- and
+4th-order effective anisotropies.",0705.1689v1
+2008-02-29,"Detailed transport investigation of the magnetic anisotropy of (Ga,Mn)As","This paper discusses transport methods for the investigation of the (Ga,Mn)As
+magnetic anisotropy. Typical magnetoresistance behaviour for different
+anisotropy types is discussed, focusing on an in depth discussion of the
+anisotropy fingerprint technique and extending it to layers with primarily
+uniaxial magnetic anisotropy. We find that in all (Ga,Mn)As films studied,
+three anisotropy components are always present. The primary biaxial along
+([100] and [010]) along with both uniaxial components along the [110] and [010]
+crystal directions which are often reported separately. Various fingerprints of
+typical (Ga,Mn)As transport samples at 4 K are included to illustrate the
+variation of the relative strength of these anisotropy terms. We further
+investigate the temperature dependence of the magnetic anisotropy and the
+domain wall nucleation energy with the help of the fingerprint method.",0802.4400v1
+2011-06-01,Enhancement of magnetic anisotropy barrier in long range interacting spin systems,"Magnetic materials are usually characterized by anisotropy energy barriers
+which dictate the time scale of the magnetization decay and consequently the
+magnetic stability of the sample. Here we present a unified description, which
+includes coherent rotation and nucleation, for the magnetization decay in
+generic anisotropic spin systems. In particular, we show that, in presence of
+long range exchange interaction, the anisotropy energy barrier grows as the
+volume of the particle for on site anisotropy, while it grows even faster than
+the volume for exchange anisotropy, with an anisotropy energy barrier
+proportional to $V^{2-\alpha/d}$, where $V$ is the particle volume, $\alpha
+\leq d $ is the range of interaction and $d$ is the embedding dimension. These
+results shows a relevant enhancement of the anisotropy energy barrier w.r.t.
+the short range case, where the anisotropy energy barrier grows as the particle
+cross sectional area for large particle size or large particle aspect ratio.",1106.0148v2
+2013-03-04,Switching of anisotropy and phase diagram of a Heisenberg square lattice S=1/2 antiferromagnet Cu(pz)2(ClO4)2,"Experiments in the antiferromagnetic phase of a quasi 2D $S=1/2$ quasi-square
+lattice antiferromagnet Cu(pz)2(ClO4)2 reveal a biaxial type of the anisotropy,
+instead of the easy-plane one, considered before. The weak in-plane anisotropy,
+found by means of electron spin resonance spectroscopy and magnetization
+measurements, is about an order of magnitude weaker, than the off-plane
+anisotropy. The weak in-plane anisotropy results in a spin-flop phase
+transition for the magnetic field aligned along easy axis, and, thereby, in a
+bicritical point on the phase diagram. A remarkable feature of the weak
+in-plane anisotropy is the abrupt change of its sign at the spin-flop point.
+This anisotropy switching disappears at the tilting of magnetic field to the
+easy axis by the angle of 10$^\circ$ within the plane. The nature of the abrupt
+anisotropy reversal remains unclear. The phase diagram is characterized by the
+increase of the ordering temperature in the magnetic field used, except for a
+dip near the bicritical point.",1303.0619v2
+2013-09-18,Chiral Symmetry Breaking: To Probe Anisotropy and Magnetic Field in QGP,"We discuss the (spontaneous) chiral symmetry breaking in a strongly coupled
+anisotropic quark-gluon plasma (QGP) in the presence of the magnetic field,
+using holography. The physical quantities related to the chiral symmetry
+breaking (m;B_c) distinguish between the effects of the anisotropy and magnetic
+field on the plasma. Anisotropy affects the system similar to the temperature
+and for its larger values heavier quarks can live in the QGP without getting
+condensed. Raising the anisotropy in the system will also increase the value of
+the critical magnetic field, B_c, at which the spontaneous chiral symmetry
+breaking happens. Both of these growths are even more when the magnetic field
+is applied perpendicular to the anisotropy direction. Such behaviour persists
+in the high temperature limit where the temperature is kept fixed. However,
+when the entropy density is held fixed, as one increases the anisotropy,
+lighter mesons melt when the magnetic field is applied along the anisotropy
+direction, in contrast to when the magnetic field is perpendicular to the
+anisotropy direction.",1309.4715v2
+2013-11-03,Primordial Anisotropies in Gauged Hybrid Inflation,"We study primordial anisotropies generated in the model of gauged hybrid
+inflation in which the complex waterfall field is charged under a $U(1)$ gauge
+field. Primordial anisotropies are generated either actively during inflation
+or from inhomogeneities modulating the surface of end of inflation during
+waterfall transition. We present a consistent $\delta N$ mechanism to calculate
+the anisotropic power spectrum and bispectrum. We show that the primordial
+anisotropies generated at the surface of end of inflation do not depend on the
+number of e-folds and therefore do not produce dangerously large anisotropies
+associated with the IR modes. Furthermore, one can find the parameter space
+that the anisotropies generated from the surface of end of inflation cancel the
+anisotropies generated during inflation, therefore relaxing the constrains on
+model parameters imposed from IR anisotropies. We also show that the gauge
+field fluctuations induce a red-tilted power spectrum so the averaged power
+spectrum from the gauge field can change the total power spectrum from blue to
+red. Therefore, hybrid inflation, once gauged under a $U(1)$ field, can be
+consistent with the cosmological observations.",1311.0493v2
+2014-04-05,Anisotropy-based mechanism for zigzag striped patterns in magnetic thin films,"In this work we studied a two dimensional ferromagnetic system using Monte
+Carlo simulations. Our model includes exchange and dipolar interactions, a
+cubic anisotropy term, and uniaxial out-of-plane and in-plane ones. According
+to the set of parameters chosen, the model including uniaxial out-of-plane
+anisotropy has a ground-state which consists of a canted state with stripes of
+opposite out-of-plane magnetization. When the cubic anisotropy is introduced
+zigzag patterns appear in the stripes at fields close to the remanence. An
+analysis of the anisotropy terms of the model shows that this configuration is
+related to specific values of the ratio between the cubic and the effective
+uniaxial anisotropy. The mechanism behind this effect is related to particular
+features of the anisotropy's energy landscape, since a global minima transition
+as a function of the applied field is required in the anisotropy terms. This
+new mechanism for zigzags formation could be present in monocrystal
+ferromagnetic thin films in a given range of thicknesses.",1404.1526v2
+2015-12-24,Magnetization of superparamagnetics in the state of mechanical anisotropy,"The internal energy of magnetic anisotropy for some nanoparticles dominates
+over the thermal energy even at room temperature. Strong magnetic anisotropy of
+nanoparticles can significantly affect the process of magnetization of the
+magnetic fluid. This influence is substantial if the system of nanoparticles is
+in a state of mechanical anisotropy in which the anisotropy axes of the
+particles have the same direction. In this work, it is shown that the
+magnetization curve of the magnetic fluid in a state of mechanical anisotropy
+is significantly different from that of Langevin. It is located between the
+Langevin and hyperbolic tangent curves and with increasing anisotropy takes
+progressively the hyperbolic tangent shape. It is also shown that in case of
+powder samples, the mechanical anisotropy leads to substantial quantitative
+changes in the Curie law.",1512.07751v2
+2016-10-18,Dichotomy between in-plane magnetic susceptibility and resistivity anisotropies in extremely strained $BaFe_{2}As_{2}$,"The in-plane resistivity and uniform magnetic susceptibility anisotropies of
+$BaFe_{2}As_{2}$ are obtained with a new method, in which a large
+symmetry-breaking uniaxial strain is applied using a substrate with a very
+anisotropic thermal expansion. The resistivity anisotropy and its corresponding
+elastoresistivity exhibit very similar diverging behavior as those obtained
+from piezo-stack experiments. This suggests that the resistivity anisotropy is
+more a direct measure of magnetism than of nematicity, since the nematic
+transition is no longer well-defined under a large strain. In strong contrast
+to the large resistivity anisotropy above $T_{N}$, the anisotropy of the
+in-plane magnetic susceptibility develops largely below $T_{N}$. Using an
+itinerant model, we show that the observed anisotropy ($\chi_{b}>\chi_{a}$) is
+determined by spin-orbit coupling and the orientation of the magnetic moments
+in the antiferromagnetic phase, and that the anisotropy is dominated by
+intra-orbital ($yz,yz$) contributions of the Umklapp susceptibility.",1610.05575v2
+2016-12-06,Origin of Small-Scale Anisotropies in Galactic Cosmic Rays,"The arrival directions of Galactic cosmic rays (CRs) are highly isotropic.
+This is expected from the presence of turbulent magnetic fields in our Galactic
+environment that repeatedly scatter charged CRs during propagation. However,
+various CR observatories have identified weak anisotropies of various angular
+sizes and with relative intensities of up to a level of 1 part in 1,000.
+Whereas large-scale anisotropies are generally predicted by standard diffusion
+models, the appearance of small-scale anisotropies down to an angular size of
+10 degrees is surprising. In this review, we summarise the current experimental
+situation for both the large-scale and small-scale anisotropies. We address
+some of the issues in comparing different experimental results and remaining
+questions in interpreting the observed large-scale anisotropies. We then review
+the standard diffusive picture and its difficulty in producing the small-scale
+anisotropies. Having set the stage, we review the various ideas and models put
+forward for explaining the small-scale anisotropies.",1612.01873v1
+2018-09-07,Anisotropy-driven collisional separation of impurities in magnetized compressing and expanding cylindrical plasmas,"When a cylindrically-symmetric magnetized plasma compresses or expands,
+velocity-space anisotropy is naturally generated as a result of the different
+adiabatic conservation laws parallel and perpendicular to the magnetic field.
+When the compression timescale is comparable to the collision timescale, and
+both are much longer than the gyroperiod, this pressure anisotropy can become
+significant. We show that this naturally-generated anisotropy can dramatically
+affect the transport of impurities in the compressing plasma, even in the
+absence of scalar temperature or density gradients, by modifying the azimuthal
+frictions that give rise to radial particle transport. Although the impurity
+transport direction depends only on the sign of the pressure anisotropy, the
+anisotropy itself depends on the pitch magnitude of the magnetic field and the
+sign of the radial velocity. Thus, pressure anisotropy effects can drive
+impurities either towards or away from the plasma core. These
+anisotropy-dependent terms represent a qualitatively new effect, influencing
+transport particularly in the sparse edge regions of dynamically-compressing
+screw pinch plasmas. Such plasmas are used for both X-ray generation and
+magneto-inertial fusion, applications which are sensitive to impurity
+concentrations.",1809.02528v1
+2024-02-01,Legendre Expansion for Scattering Anisotropy in Analytical 1D Multigroup $S_N$ Equations,"We demonstrate the scattering anisotropy treatment of the previously
+developed analytical solution for 1D multigroup $S_N$ equations.",2402.01017v1
+2003-05-29,Theoretical Overview of Cosmic Microwave Background Anisotropy,"The theoretical basis for the prediction of anisotropies in the cosmic
+microwave background is very well developed. Very low amplitude density and
+temperature perturbations produce small gravitational effects, leading to an
+anisotropy that is a combination of temperature fluctuations at the surface of
+last scattering and gravitational redshifts both at last scattering and along
+the path to the observer. All of the primary anisotropy can be handled by
+linear perturbation theory, which allows a very accurate calculation of the
+predicted anisotropy from different models of the Universe.",0305591v1
+2006-11-07,CMB anisotropies due to cosmological magnetosonic waves,"We study scalar mode perturbations (magnetosonic waves) induced by a helical
+stochastic cosmological magnetic field and derive analytically the
+corresponding cosmic microwave background (CMB) temperature and polarization
+anisotropy angular power spectra. We show that the presence of a stochastic
+magnetic field, or an homogeneous magnetic field, influences the acoustic
+oscillation pattern of the CMB anisotropy power spectrum, effectively acting as
+a reduction of the baryon fraction. We find that the scalar magnetic energy
+density perturbation contribution to the CMB temperature anisotropy is small
+compared to the contribution to the CMB $E$-polarization anisotropy.",0611247v2
+2007-01-17,Wind anisotropies and GRB progenitors,"We study the effect of wind anisotropies on the stellar evolution leading to
+collapsars. Rotating models of a 60 M$_\odot$ star with $\Omega/\Omega_{\rm
+crit}=0.75$ on the ZAMS, accounting for shellular rotation and a magnetic
+field, with and without wind anisotropies, are computed at $Z$=0.002 until the
+end of the core He-burning phase. Only the models accounting for the effects of
+the wind anisotropies retain enough angular momentum in their core to produce a
+Gamma Ray Burst (GRB). The chemical composition is such that a type Ic
+supernova event occurs. Wind anisotropies appear to be a key physical
+ingredient in the scenario leading to long GRBs.",0701494v1
+1992-09-18,Discrete to Continuous-Time Crossover due to Anisotropy in Diffusion-Limited Two-Particle Annihilation Reactions,"Diffusion-limited reaction A+A->inert with anisotropic hopping on the d=1
+lattice, is solved exactly for a simultaneous updating, discrete time-step
+dynamics. Diffusion-dominated processes slow down as the anisotropy increases.
+For large times or large anisotropy, one can invoke the appropriate continuum
+limits. In these limits the effects of the anisotropy on variation of particle
+density can be absorbed in time rescaling. However, in other regimes, when the
+discreteness of the time steps is nonnegligible, the anisotropy effects are
+nontrivial, although they are always quite small numerically.",9209024v1
+1996-02-19,Stress-free Spatial Anisotropy in Phase-Ordering,"We find spatial anisotropy in the asymptotic correlations of two-dimensional
+Ising models under non-equilibrium phase-ordering. Anisotropy is seen for
+critical and off-critical quenches and both conserved and non-conserved
+dynamics. We argue that spatial anisotropy is generic for scalar systems
+(including Potts models) with an anisotropic surface tension. Correlation
+functions will not be universal in these systems since anisotropy will depend
+on, e.g., temperature, microscopic interactions and dynamics, disorder, and
+frustration.",9602097v1
+1998-11-23,Giant enhancement of anisotropy by electron-phonon interaction,"Anisotropic electron-phonon interaction is shown to lead to the anisotropic
+polaron effect. The resulting anisotropy of the polaron band is an exponential
+function of the electron-phonon coupling and might be as big as $10^3$. This
+also makes anisotropy very sensitive to small changes of coupling and implies
+wide variations of anisotropy among compounds of similar structure. The isotope
+effect on mass anisotropy is predicted. Polaron masses are obtained by an exact
+Quantum Monte Carlo method. Implications for high-temperature superconductors
+are briefly discussed.",9811327v1
+1999-05-09,A simple solid-on-solid model of epitaxial thin films growth: surface morphology anisotropy,"In this paper we present a generalization of a simple solid-on-solid
+epitaxial model of thin films growth, when surface morphology anisotropy is
+provoked by anisotropy in model control parameters: binding energy and/or
+diffusion barrier. The anisotropy is discussed in terms of the height-height
+correlation function. It was experimentally confirmed that the difference in
+diffusion barriers yields anisotropy in morphology of the surface. We got
+antisymmetric correlations in the two in-plane directions for antisymmetric
+binding.",9905111v2
+2001-06-18,Phase Transition in the Random Anisotropy Model,"The influence of a local anisotropy of random orientation on a ferromagnetic
+phase transition is studied for two cases of anisotropy axis distribution. To
+this end a model of a random anisotropy magnet is analyzed by means of the
+field theoretical renormalization group approach in two loop approximation
+refined by a resummation of the asymptotic series. The one-loop result of
+Aharony indicating the absence of a second-order phase transition for an
+isotropic distribution of random anisotropy axis at space dimension $d<4$ is
+corroborated. For a cubic distribution the accessible stable fixed point leads
+to disordered Ising-like critical exponents.",0106334v1
+2002-10-04,Surface contribution to the anisotropy of magnetic nanoparticles,"We calculate the contribution of the Neel surface anisotropy to the effective
+anisotropy of magnetic nanoparticles of spherical shape cut out of a simple
+cubic lattice. The effective anisotropy arises because deviations of atomic
+magnetizations from collinearity and thus the energy depends on the orientation
+of the global magnetization. The result is second order in the Neel surface
+anisotropy, scales with the particle volume and has cubic symmetry with
+preferred directions [+-1,+-1,+-1].",0210098v1
+2003-04-08,Novel surface anisotropy term in the FMR spectra of amorphous microwires,"Some recent publications on ferromagnetic resonance in amorphous wires
+mention presumably new kind of anisotropy, called there circumferential
+anisotropy, as an explanation of various spectral features. In this paper we
+argue that there is no special reason to speak of the new kind of anisotropy,
+since the observed spectra can be well described in terms of more traditional
+uniaxial and surface anisotropies alone.",0304195v1
+2003-07-17,Surface anisotropy in nanomagnets: transverse or Néel ?,"Through the hysteresis loop and magnetization spatial distribution we study
+and compare two models for surface anisotropy in nanomagnets: a model with
+transverse anisotropy axes and N\'eel's model. While surface anisotropy in the
+transverse model induces several jumps in the hysteresis loop because of the
+cluster-wise switching of spins, in the N\'eel model the jumps correspond to
+successive {\it coherent partial rotations} of the whole bunch of spins. These
+calculations together with experimental results suggest that N\'eel's model for
+surface anisotropy is more appropriate.",0307436v2
+2004-10-04,Effects of Antiferromagnetic Spin Rotation on Anisotropy of Ferromagnetic/Antiferromagnetic Bilayers,"In epitaxial (111) oriented Ni$_{80}$Fe$_{20}$/Fe$_{50}$Mn$_{50}$ bilayers,
+we separate two distinct behaviors: unidirectional anisotropy (exchange bias)
+in thick Fe$_{50}$Mn$_{50}$, and enhanced coercivity in thin
+Fe$_{50}$Mn$_{50}$. By measuring the magnetization response to a rotating
+magnetic field, we quantitatively determine the relevant anisotropies, and
+demonstrate that the enhanced coercivity is related to the rotatable magnetic
+anisotropy of Fe$_{50}$Mn$_{50}$. We also demonstrate the consequences of the
+anisotropy changes with temperature.",0410091v1
+2005-10-03,Surface-induced cubic anisotropy in nanomagnets,"We investigate the effect of surface anisotropy in a spherical many-spin
+magnetic nanoparticle. By computing minor loops, two-dimensional (2D) and 3D
+energyscape, and by investigating the behavior of the net magnetization, we
+show that in the case of not too strong surface anisotropy the behavior of the
+many-spin particle may be modeled by that of a macrospin with an effective
+energy containing uniaxial and cubic anisotropy terms. This holds for both the
+transverse and N\'eel's surface anisotropy models.",0510047v3
+2005-10-21,ESR study of the single-ion anisotropy in the pyrochlore antiferromagnet Gd2Sn2O7,"Single-ion anisotropy is of importance for the magnetic ordering of the
+frustrated pyrochlore antiferromagnets Gd2Ti2O7 and Gd2Sn2O7. The anisotropy
+parameters for the Gd2Sn2O7 were measured using the electron spin resonance
+(ESR) technique. The anisotropy was found to be of the easy plane type, with
+the main constant D=140mK. This value is 35% smaller than the value of the
+corresponding anisotropy constant in the related compound Gd2Ti2O7.",0510575v1
+2006-09-13,Determination of the resistivity anisotropy of SrRuO$_{3}$ by measuring the planar Hall effect,"We have measured the planar Hall effect in epitaxial thin films of the
+itinerant ferromagnet SrRuO3 patterned with their current paths at different
+angles relative to the crystallographic axes. Based on the results, we have
+determined that SrRuO3 exhibits small resistivity anisotropy in the entire
+temperature range of our measurements (between 2 to 300 K); namely, both above
+and below its Curie temperature (~150 K). It means that in addition to
+anisotropy related to magnetism, the resistivity anisotropy of SrRuO3 has an
+intrinsic, nonmagnetic source. We have found that the two sources of anisotropy
+have competing effects.",0609321v1
+2006-12-17,"Lithographic engineering of anisotropies in (Ga,Mn)As","The focus of studies on ferromagnetic semiconductors is moving from material
+issues to device functionalities based on novel phenomena often associated with
+the anisotropy properties of these materials. This is driving a need for a
+method to locally control the anisotropy in order to allow the elaboration of
+devices. Here we present a method which provides patterning induced anisotropy
+which not only can be applied locally, but also dominates over the intrinsic
+material anisotropy at all temperatures.",0612439v1
+2007-05-10,Effective anisotropy of thin nanomagnets: beyond the surface anisotropy approach,"We study the effective anisotropy induced in thin nanomagnets by the nonlocal
+demagnetization field (dipole-dipole interaction). Assuming a magnetization
+independent of the thickness coordinate, we reduce the energy to an
+inhomogeneneous onsite anisotropy. Vortex solutions exist and are ground states
+for this model. We illustrate our approach for a disk and a square geometry. In
+particular, we obtain good agreement between spin-lattice simulations with this
+effective anisotropy and micromagnetic simulations.",0705.1555v2
+2007-07-28,Long-range order in the A-like phase of superfluid 3He in aerogel,"A mutual action of the random anisotropy brought in the superfluid 3He by
+aerogel and of the global anisotropy caused by its deformation is considered.
+Strong global anisotropy tends to suppress fluctuations of orientation of the
+order parameter and stabilizes ABM order parameter. In a limit of vanishing
+anisotropy these fluctuations are getting critical. It is argued that still in
+a region of small fluctuations the average order parameter can acquire ""robust""
+component. This component maintains a long-range order even in a limit of
+vanishing global anisotropy.",0707.4222v2
+2007-09-26,Single crystal growth and anisotropy of CeRuPO,"We report on the single crystal growth of the ferromagnetic Kondo lattice
+system CeRuPO using a Sn flux method. Magnetic susceptibility and electrical
+resistivity measurements indicate strong anisotropy of this structurally
+layered compound. They evidence that the magnetic moments order
+ferromagnetically along the c-direction of the tetragonal unit cell, whereas
+the crystal electric field (CEF) anisotropy favors the ab-plane. Therefore,
+CeRuPO presents the unusual case within rare earth systems, where the
+anisotropy of the interionic exchange interaction overcomes the single ion
+anisotropy due to the CEF interaction.",0709.4144v2
+2009-01-19,Local magnetic anisotropy controlled by a surface nano-modulation,"A topological modulation of magnetic thin films can induce a magnetic
+anisotropy of magnetostatic origin. In this letter, we report on the magnetic
+properties of NiFe layers deposited on wavy shaped Si substrates. Without any
+modulation, our films always present an intrinsic anisotropy. We show
+unambiguously that patterning the substrate can overcome this anisotropy and
+even impose a different easy axis of magnetization. This allows the definition
+of two orthogonal easy axes at different places on the same substrate. This
+control of anisotropy both in direction and intensity paves the way to the
+realization of high precision bidimensional magnetic sensors.",0901.2617v1
+2009-05-01,Finite electric field effects in the large perpendicular magnetic anisotropy surface Pt/Fe/Pt(001),"We have investigated crystalline magnetic anisotropy in the electric field
+(EF) for the Fe-Pt surface which have a large perpendicular anisotropy, by
+means of the first-principles approach. The anisotropy is reduced linearly with
+respect to the inward EF, associated with the induced spin density around the
+Fe layer. Although the magnetic anisotropy energy (MAE) density reveals the
+large variation around the atoms, the intrinsic contribution to the MAE is
+found to mainly come from the Fe layer.",0905.0060v1
+2009-11-26,Macrospin limit and configurational anisotropy in nanoscale Permalloy triangles,"In Permalloy submicron triangles, configurational anisotropy - a higher-order
+form of shape anisotropy - yields three equivalent easy axes, imposed by the
+structures' symmetry order. Supported by micromagnetic simulations, an
+experimental method was devised to evaluate the nanostructure dimensions for
+which a Stoner-Wohlfarth type of reversal could be used to describe this
+particular magnetic anisotropy. In this regime, a straightforward procedure
+using an in-plane rotating field allowed us to quantify experimentally the
+six-fold anisotropy fields for triangles of different thicknesses and sizes.",0911.5121v1
+2009-12-01,Vertically Graded Anisotropy in Co/Pd Multilayers,"Depth-grading of magnetic anisotropy in perpendicular magnetic media has been
+predicted to reduce the field required to write data without sacrificing
+thermal stability. To study this prediction, we have produced Co/Pd multilayers
+with depth-dependent Co layer thickness. Polarized neutron reflectometry shows
+that the thickness grading results in a corresponding magnetic anisotropy
+gradient. Magnetometry reveals that the anisotropy gradient promotes domain
+nucleation upon magnetization reversal - a clear experimental demonstration of
+the effectiveness of graded anisotropy for reducing write-field.",0912.0256v1
+2010-05-07,On non-linear CMB temperature anisotropy from gravitational perturbations,"Non-linear CMB temperature anisotropies up to the third-order on large scales
+are calculated. On large scales and in the Sachs-Wolfe limit, we give the
+explicit expression for the observed temperature anisotropy in terms of the
+primordial curvature perturbation up to the third-order. We derived the final
+bispectrum and trispectrum of anisotropies and the corresponding non-linear
+parameters, in which the contributions to the observed non-Gaussianity from
+primordial perturbations and from the non-linear mapping from primordial
+curvature perturbation to the temperature anisotropy are transparently
+separated.",1005.1219v1
+2010-08-30,Dynamical electronic nematicity from Mott physics,"Very large anisotropies in transport quantities have been observed in the
+presence of very small in-plane structural anisotropy in many strongly
+correlated electron materials. By studying the two-dimensional Hubbard model
+with dynamical-mean-field theory for clusters, we show that such large
+anisotropies can be induced without static stripe order if the interaction is
+large enough to yield a Mott transition. Anisotropy decreases at large
+frequency. The maximum effect on conductivity anisotropy occurs in the
+underdoped regime, as observed in high temperature superconductors.",1008.5118v2
+2012-12-05,"Influence of Magnetic Anisotropy on Laser-induced Precession of Magnetization in Ferromagnetic Semiconductor (Ga,Mn)As","The laser-induced precession of magnetization in (Ga,Mn)As samples with
+different magnetic anisotropy was studied by the time-resolved magneto-optical
+method. We observed that the dependence of the precession amplitude on the
+external magnetic field depends strongly on the magnetic anisotropy of
+(Ga,Mn)As and we explain this phenomenon in terms of competing cubic and
+uniaxial anisotropies. We also show that the corresponding anisotropy fields
+can be deduced from the magnetic field dependence of the precession frequency.",1212.0962v1
+2013-03-01,Electrically tunable three-dimensional g-factor anisotropy in single InAs self-assembled quantum dots,"Three-dimensional anisotropy of the Lande g-factor and its electrical
+modulation are studied for single uncapped InAs self-assembled quantum dots
+(QDs). The g-factor is evaluated from measurement of inelastic cotunneling via
+Zeeman substates in the QD for various magnetic field directions. We find that
+the value and anisotropy of the g-factor depends on the type of orbital state
+which arises from the three-dimensional confinement anisotropy of the QD
+potential. Furthermore, the g-factor and its anisotropy are electrically tuned
+by a side-gate which modulates the confining potential.",1303.0158v1
+2013-10-12,Inversion Phenomena of the Anisotropies of the Hamiltonian and the Wave Function in Quantum Spin Chains,"We investigate the inversion phenomena between the XXZ anisotropies of the
+Hamiltonian and the wave function in quantum spin chains. We focus on the S=1/2
+geometrically frustrated 3-leg ladder system with the XXZ interaction
+anisotropy. By use of the degenerate perturbation theory from the strong rung
+coupling limit, we have obtained the ground-state phase diagram. In some
+parameter regions, the Tomonaga-Luttinger spin liquid state is realized in
+spite of the Ising-like anisotropy, and the Neel state in spite of the XY-like
+anisotropy.",1310.3394v1
+2014-11-06,Phenomenological description of anisotropy effects in some ferromagnetic superconductors,"We study phenomenologically by using the previously derived Landau free
+energy, the role of anisotropy in ferromagnetic superconductors UGe2, URhGe,
+and UCoGe. The three compounds are separately discussed with the special stress
+on UGe2. The main effect comes from the strong uniaxial anisotropy of
+magnetization while the anisotropy of Cooper pairs and crystal anisotropy only
+slightly change the phase diagram in the vicinity of Curie temperature. The
+limitations of this approach are also discussed.",1411.1748v1
+2015-02-05,DFT calculations of magnetic anisotropy energy for GeMnTe ferromagnetic semiconductor,"Density functional theory (DFT) calculations of the energy of magnetic
+anisotropy for diluted ferromagnetic semiconductor GeMnTe were performed using
+using OpenMX package with fully relativistic pseudopotentials. The influence of
+hole concentration and magnetic ion neighborhood on magnetic anisotropy energy
+is presented. Analysis of microscopic mechanism of magnetic anisotropy is
+provided, in particular the role of spin-orbit coupling, spin polarization and
+spatial changes of electron density are discussed. The calculations are in
+accordance with the experimental observation of perpendicular magnetic
+anisotropy in rhombohedral GeMnTe (111) thin layers.",1502.01715v3
+2015-04-28,"""Switching"" of Magnetic Anisotropy in a fcc Antiferromagnet with Direction-Dependent Interactions","Direction-dependent anisotropic exchange is a common feature of magnetic
+systems with strong spin-orbit coupling. Here we study the effect of such
+exchange upon macroscopic magnetic anisotropy for a face-centered-cubic model.
+By several theoretical techniques, we show that, both in the paramagnetic and
+ordered phases, the magnetic anisotropy is induced by fluctuations. Moreover,
+the magnetic anisotropy differs in the paramagnetic and ordered phases: in the
+paramagnetic phase the susceptibility is maximum along the $\langle111\rangle$
+directions, while the magnetic moments orient along $\langle110\rangle$ or
+$\langle100\rangle$ in the ordered phase. We suggest that such ""anisotropy
+switching"" can be a common feature of strongly spin-orbit coupled magnets.",1504.07607v1
+2015-11-16,Strong Transport Anisotropy in a Ge/SiGe Quantum Well in Tilted Magnetic Fields,"We report on a strong transport anisotropy in a 2D hole gas in a Ge/SiGe
+quantum well, which emerges only when both perpendicular and in-plane magnetic
+fields are present. The ratio of resistances, measured along and perpendicular
+to the in-plane field, can exceed $3\times 10^4$. The anisotropy occurs in a
+wide range of filling factors where it is determined {\em primarily} by the
+tilt angle. The lack of significant anisotropy without an in-plane field, easy
+tunability, and persistence to higher temperatures and filling factors set this
+anisotropy apart from nematic phases in GaAs/AlGaAs.",1511.05167v1
+2017-08-05,Magnetization reversal of thin ferromagnetic elements with surface anisotropy,"The magnetization reversal process in thin-film ferromagnetic elements with
+surface anisotropy of various shapes and sizes is investigated by means of
+numerical simulation. The dependence of the perpendicular and in-plane
+hysteresis loops on the element thickness and the value of the surface
+anisotropy constant is obtained. For sufficiently large values of the surface
+anisotropy constant the magnetization reversal of thin-film elements is shown
+to occur due to the nucleation of the buckling mode. For an elongated
+rectangular element the nucleation field of the buckling mode is proportional
+to the absolute value of the surface anisotropy constant, and inversely
+proportional to the element thickness.",1708.01802v1
+2021-10-27,The nonlinear anisotropic model of the Universe with the linear potential,"In the Bianchi I cosmology some subclasses of the Horndeski theory allow for
+the non-standard anisotropy behavior. For example, the anisotropy is damped
+near the initial singularity instead of tending to infinity. In this article,
+we analyze the nonlinear anisotropic model with the linear potential.We have
+considered an example of such theory, for which the anisotropy is always
+finite. The anisotropy reaches its a maximum value at the initial moment. The
+anisotropy suppression occurs during the inflationary stage, and it approaches
+zero at later times. This cosmological model does not contain the singular
+point.",2110.14630v2
+2022-11-21,Giant Magnetochiral Anisotropy in Weyl-semimetal WTe2 Induced by Diverging Berry Curvature,"The concept of Berry curvature is essential for various transport phenomena.
+However, an effect of the Berry curvature on magnetochiral anisotropy, i.e.
+nonreciprocal magneto-transport, is still elusive. Here, we report the Berry
+curvature originates the large magnetochiral anisotropy. In Weyl-semimetal
+WTe2, we observed the strong enhancement of the magnetochiral anisotropy when
+the Fermi level is located near the Weyl points. Notably, the maximal figure of
+merit $\bar{\gamma}$ reaches $1.2\,{\times}10^{-6} \rm{m^2T^{-1}A^{-1}}$, which
+is the largest ever reported in bulk materials. Our semiclassical calculation
+shows that the diverging Berry curvature at the Weyl points strongly enhances
+the magnetochiral anisotropy.",2211.11231v1
+2022-12-29,Localized Spin-Wave Modes and Microwave Absorption in Random-Anisotropy Ferromagnets,"The theory of localized spin-wave excitations in random-anisotropy magnets
+has been developed. Starting with a pure Heisenberg ferromagnet, we study the
+evolution of standing spin waves in a finite-size sample towards localized
+modes on increasing the strength of random anisotropy. Profiles of the
+localized modes and their phases are analyzed and visualized in a 2D sample.
+Localization length is obtained by several methods and its dependence on random
+anisotropy is computed. The connection between the localization of spin
+excitations and the broadband nature of the absorption of microwave power by
+random-anisotropy magnets is elucidated.",2212.14301v1
+2024-01-09,Pulsar Kick by the Chiral Anisotropy Conversion,"We discuss a novel mechanism for the proto-neutron star acceleration assisted
+by the chiral separation effect which induces an axial vector current in a
+dense medium. We consider the process of neutrinos scattering off the
+background axial vector current of electrons. We show that anisotropy of either
+magnetic field or density in momentum space is essential for nonzero recoil and
+we call this mechanism the chiral anisotropy conversion. Assuming a strong
+magnetic field $B \simeq 10^{12}$ T and anisotropy by $\sim 10\%$, we find that
+the chiral anisotropy conversion can yield the velocity of order of typical
+pulsar kicks, i.e., $v_{\mathrm{kick}} \gtrsim 1000$ km/s.",2401.04568v1
+2011-12-06,Domain-Wall Pinning by Local Control of Anisotropy in Pt/Co/Pt strips,"We theoretically and experimentally analyze the pinning of a magnetic domain
+wall (DW) at engineered anisotropy variations in Pt/Co/Pt strips with
+perpendicular magnetic anisotropy. An analytical model is derived showing that
+a step in the anisotropy acts as an energy barrier for the DW. Quantitative
+measurements are performed showing that the anisotropy can be controlled by
+focused ion beam irradiation with Ga ions. This tool is used to experimentally
+study the field-induced switching of nanostrips which are locally irradiated.
+The boundary of the irradiated area indeed acts as a pinning barrier for the
+domain wall and the pinning strength increases with the anisotropy difference.
+Varying the thickness of the Co layer provides an additional way to tune the
+anisotropy, and it is shown that a thinner Co layer gives a higher starting
+anisotropy thereby allowing tunable DW pinning in a wider range of fields.
+Finally, we demonstrate that not only the anisotropy itself, but also the width
+of the anisotropy barrier can be tuned on the length scale of the domain wall.",1112.1259v2
+2019-03-29,Anisotropy of the Universe via the Pantheon supernovae sample revisited,"We employ the hemisphere comparison (HC) method and the dipole fitting (DF)
+method to investigate the cosmic anisotropy in the recently released Pantheon
+sample of type Ia supernovae (SNe Ia) and five combinations among Pantheon. For
+the HC method, we find the maximum anisotropy level in the full Pantheon sample
+is $\mathrm{AL}_{max}=0.361\pm0.070$ and corresponding direction
+$(l,b)=({123.05^{\circ}}^{+11.25^{\circ}}_{-4.22^{\circ}},
+{4.78^{\circ}}^{+1.80^{\circ}}_{-8.36^{\circ}})$. A robust check shows the
+statistical significance of maximum anisotropy level is about $2.1\sigma$. We
+also find that the Low-$z$ and SNLS subsamples have decisive impact on the
+overall anisotropy while other three subsamples have little impact. Moreover,
+the anisotropy level map significantly rely on the inhomogeneous distribution
+of SNe Ia in the sky. For the DF method, we find the dipole anisotropy in the
+Pantheon sample is very weak. The dipole magnitude is constrained to be less
+than $1.16\times10^{-3}$ at $95\%$ confidence level. However, the dipole
+direction is well inferred by MCMC method and it points towards
+$(l,b)=({306.00^{\circ}}^{+82.95^{\circ}}_{-125.01^{\circ}},
+{-34.20^{\circ}}^{+16.82^{\circ}}_{-54.93^{\circ}})$. This direction is very
+close to the axial direction to the plane of SDSS subsample. It may imply that
+SDSS subsample is the decisive part to the dipole anisotropy in the full
+Pantheon sample. All these facts imply that the cosmic anisotropy found in
+Pantheon sample significantly rely on the inhomogeneous distribution of SNe Ia
+in the sky. More homogeneous distribution of SNe Ia is necessary to search for
+a more convincing cosmic anisotropy.",1903.12401v2
+2022-08-05,Validation of EEG forward modeling approaches in the presence of anisotropy in the source space,"The quality of the inverse approach in electroencephalography (EEG) source
+analysis is - among other things - depending on the accuracy of the forward
+modeling approach, i.e., the simulation of the electric potential for a known
+dipole source in the brain. Here, we use multilayer sphere modeling scenarios
+to investigate the performance of three different finite element method (FEM)
+based EEG forward approaches - subtraction, Venant and partial integration - in
+the presence of tissue conductivity anisotropy in the source space. In our
+studies, the effect of anisotropy on the potential is related to model errors
+when ignoring anisotropy and to numerical errors, convergence behavior and
+computational speed of the different FEM approaches. Three different source
+space anisotropy models that best represent adult, child and premature baby
+volume conduction scenarios, are used. Major findings of the study include (1)
+source space conductivity anisotropy has a significant effect on electric
+potential computation: The effect increases with increasing anisotropy ratio;
+(2) with numerical errors far below anisotropy effects, all three FEM
+approaches are able to model source space anisotropy accordingly, with the
+Venant approach offering the best compromise between accuracy and computational
+speed; (3) FE meshes have to be fine enough in the subdomain between the source
+and the sensors that capture its main activity. We conclude that, especially
+for the analysis of cortical development, but also for more general
+applications using EEG source analysis techniques, source space conductivity
+anisotropy should be modeled and the FEM Venant approach is an appropriate
+method.",2208.03081v1
+2003-05-29,Evolution of In-Plane Magnetic Anisotropy In Sputtered FeTaN/TaN/FeTaN Sandwich Films,"FeTaN/TaN/FeTaN sandwich films, FeTaN/TaN and TaN/FeTaN bilayers were
+synthesized by using RF magnetron sputtering. The magnetic properties,
+crystalline structures, microstructures and surface morphologies of the
+as-deposited samples were characterized using angle-resolved M-H loop tracer,
+VSM, XRD, TEM, AES and AFM. An evolution of the in-plane anisotropy was
+observed with the changing thickness of the nonmagnetic TaN interlayer in the
+FeTaN/TaN/FeTaN sandwiches, such as the easy-hard axis switching and the
+appearing of biaxial anisotropy. It is ascribed to three possible mechanisms,
+which are interlayer magnetic coupling, stress, and interface roughness,
+respectively. Interlayer coupling and stress anisotropies may be the major
+reasons to cause the easy-hard axis switching in the sandwiches. Whereas,
+magnetostatic and interface anisotropies may be the major reasons to cause
+biaxial anisotropy in the sandwiches, in which magnetostatic anisotropy is the
+dominant one.",0305688v1
+2007-01-19,"Control of magnetic anisotropy in (Ga,Mn)As by lithography-induced strain relaxation","We obtain control of magnetic anisotropy in epitaxial (Ga,Mn)As by
+anisotropic strain relaxation in patterned structures. The strain in the
+structures is characterized using sophisticated X-ray techniques. The magnetic
+anisotropy before patterning of the layer, which shows biaxial easy axes along
+[100] and [010], is replaced by a hard axis in the direction of large elastic
+strain relaxation and a uniaxial easy axis in the direction where pseudomorphic
+conditions are retained. This strong anisotropy can not be explained by shape
+anisotropy and is attributed solely to lattice strain relaxation. Upon
+increasing the uniaxial strain anisotropy in the (Ga,Mn)As stripes, we also
+observe an increase in magnetic anisotropy.",0701479v1
+2008-04-11,Anisotropies in the Cosmic Neutrino Background after WMAP 5-year Data,"We search for the presence of cosmological neutrino background (CNB)
+anisotropies in recent WMAP 5-year data using their signature imprinted on
+modifications to cosmic microwave background (CMB) anisotropy power spectrum.
+By parametrizing the neutrino background anisotropies with the speed viscosity
+parameter $c_\vis$, we find that the WMAP 5-year data alone provide only a weak
+indication for CNB anisotropies with $c_\vis^2 > 0.06$ at the 95% confidence
+level. When we combine CMB anisotropy data with measurements of galaxy
+clustering, SN-Ia Hubble diagram, and other cosmological information, the
+detection increases to $c_\vis^2 > 0.16$ at the same 95% confidence level.
+Future data from Planck, combined with a weak lensing survey such as the one
+expected with DUNE from space, will be able to measure the CNB anisotropy
+parameter at about 10% accuracy. We discuss the degeneracy between neutrino
+background ansiotropies and other cosmological para meters such as the number
+of effective neutrinos species and the dark energy equation of state.",0804.1925v2
+2008-04-28,Anisotropy of Galactic Cosmic Rays and New Discoveries in Its Measurements,"We discuss recently published results of two-dimensional measurements of the
+cosmic ray anisotropy in the energy range 1-100 TeV. It is demonstrated that,
+in spite of pretence of the authors to measure the anisotropy in more detail
+than it was done in one-dimensional measurements of the first harmonic of CR
+intensity in sidereal time, new measurements give nothing essentially new.
+Moreover, two-dimensional picture is misleading creating an illusion that the
+true direction of the anisotropy is observed, while, as before, only the
+projection of the anisotropy onto the equatorial plane is measured and the
+phase of the anisotropy remains to be the only directly measured parameter. The
+sophisticated interpretations of the results of 2D measurements made by their
+authors are invalid, since they are based on the false assumption that the
+equatorial excess and deficit of CR intensity seen on the difference maps
+represent the real anisotropy.",0804.4381v1
+2008-05-14,Phenomenological theory of magnetization reversal in nanosystems with competing anisotropies,"The interplay between intrinsic and surface/interface-induced magnetic
+anisotropies strongly in- fluences magnetization processes in nanomagnetic
+systems. We develop a micromagnetic theory to describe the field-driven
+reorientation in nanomagnets with cubic and uniaxial anisotropies. Spin
+configurations in competing phases and parameters of accompanying multidomain
+states are calculated as functions of the applied field and the magnetic
+anisotropies. The constructed magnetic phase diagrams allow to classify
+different types of the magnetization reversal and to provide detailed analysis
+of the switching processes in magnetic nanostructures. The calculated
+magnetization profiles of isolated domain walls show that the equilibrium
+parameters of such walls are extremely sensitive to applied magnetic field and
+values of the competing anisotropies and can vary in a broad range. For
+nanolayers with perpendicular anisotropy the geometrical parameters of stripe
+domains have been calculated as functions of a bias field. The results are
+applied to analyse the magnetization processes as observed in various
+nanosystems with competing anisotropies, mainly, in diluted magnetic
+semiconductor films (Ga,Mn)As.",0805.1984v2
+2009-02-18,Splitting of the Kondo resonance in anisotropic magnetic impurities on surfaces,"Using the numerical renormalization group method, we study the splitting of
+the Kondo resonance by a magnetic field applied in different directions in the
+Kondo model for anisotropic magnetic impurities. Several types of magnetic
+anisotropy are considered: the XXZ exchange coupling anisotropy J_perp J_z, the
+longitudinal magnetic anisotropy DS_z^2, and the transverse magnetic anisotropy
+E(S_x^2-S_y^2). In the spin-1/2 model with the XXZ exchange coupling anisotropy
+we find very small direction dependence in the magnitude of the splitting. In
+the spin-3/2 model with the easy-plane (D>0) anisotropy, we observe very
+unequal magnitudes with further differences between x and y directions in the
+presence of an additional transverse anisotropy. A simple and rather intuitive
+interpretation is that the splitting is larger in magnetically soft directions.
+The magnitude of the splitting is directly related to the energy differences
+between spin states and it is only weakly modified by some multiplicative
+factor due to Kondo screening. The results for the S=3/2 model are in good
+agreement with recent scanning tunneling spectroscopy studies of Co impurities
+adsorbed on CuN islands on Cu(100) surfaces [A. F. Otte et al., Nature Physics
+4, 847 (2008)]",0902.3119v1
+2010-06-17,Constrained Monte Carlo Method and Calculation of the Temperature Dependence of Magnetic Anisotropy,"We introduce a constrained Monte Carlo method which allows us to traverse the
+phase space of a classical spin system while fixing the magnetization
+direction. Subsequently we show the method's capability to model the
+temperature dependence of magnetic anisotropy, and for bulk uniaxial and cubic
+anisotropies we recover the low-temperature Callen-Callen power laws in M. We
+also calculate the temperature scaling of the 2-ion anisotropy in L10 FePt, and
+recover the experimentally observed M^2.1 scaling. The method is newly applied
+to evaluate the temperature dependent effective anisotropy in the presence of
+the N'eel surface anisotropy in thin films with different easy axis
+configurations. In systems having different surface and bulk easy axes, we show
+the capability to model the temperature-induced reorientation transition. The
+intrinsic surface anisotropy is found to follow a linear temperature behavior
+in a large range of temperatures.",1006.3507v1
+2011-06-03,Single-ion versus two-ion anisotropy in magnetic compounds: A neutron scattering study,"Anisotropy effects can significantly control or modify the ground-state
+properties of magnetic systems. Yet the origin and the relative importance of
+the possible anisotropy terms is difficult to assess experimentally and often
+ambiguous. Here we propose a technique which allows a very direct distinction
+between single-ion and two-ion anisotropy effects. The method is based on
+high-resolution neutron spectroscopic investigations of magnetic cluster
+excitations. This is exemplified for manganese dimers and tetramers in the
+mixed compounds CsMnxMg1-xBr3 (0.05\leqx\leq0.40). Our experiments provide
+evidence for a pronounced anisotropy of the order of 3% of the dominant
+bilinear exchange interaction, and the anisotropy is dominated by the
+single-ion term. The detailed characterization of magnetic cluster excitations
+offers a convenient way to unravel anisotropy effects in any magnetic material.",1106.0615v1
+2011-11-16,Macrospin approximation and quantum effects in models for magnetization reversal,"The thermal activation of magnetization reversal in magnetic nanoparticles is
+controlled by the anisotropy-energy barrier. Using perturbation theory, exact
+diagonalization and stability analysis of the ferromagnetic spin-s Heisenberg
+model with coupling or single-site anisotropy, we study the effects of quantum
+fluctuations on the height of the energy barrier. Opposed to the classical
+case, there is no critical anisotropy strength discriminating between reversal
+via coherent rotation and via nucleation/domain-wall propagation. Quantum
+fluctuations are seen to lower the barrier depending on the anisotropy
+strength, dimensionality and system size and shape. In the weak-anisotropy
+limit, a macrospin model is shown to emerge as the effective low-energy theory
+where the microscopic spins are tightly aligned due to the ferromagnetic
+exchange. The calculation provides explicit expressions for the anisotropy
+parameter of the effective macrospin. We find a reduction of the
+anisotropy-energy barrier as compared to the classical high spin-s limit.",1111.3900v1
+2012-08-08,Effect of Co doping on the in-plane anisotropy in the optical spectrum of underdoped Ba(Fe1-xCox)2As2,"We investigated the anisotropy in the in-plane optical spectra of detwinned
+Ba(Fe1-xCox)2As2. The optical conductivity spectrum of BaFe2As2 shows
+appreciable anisotropy in the magnetostructural ordered phase, whereas the dc
+resistivity is almost isotropic at low temperatures. Upon Co doping, the
+resistivity becomes highly anisotropic, while the finite-energy intrinsic
+anisotropy is suppressed. It is found that anisotropy in resistivity arises
+from anisotropic impurity scattering from doped Co atoms, extrinsic in origin.
+Intensity of a specific optical phonon mode is also found to show striking
+anisotropy in the ordered phase. The anisotropy induced by Co impurity and that
+observed in the optical phonon mode are hallmarks of the highly polarizable
+electronic state in the ordered phase.",1208.1581v1
+2012-10-18,Single-domain shape anisotropy in near-macroscopic Ni$_{80}$Fe$_{20}$ thin-film rectangles,"Shape anisotropy provides a simple mechanism to adjust the local bias field
+in patterned structures. It is well known that for ellipsoidal particles $<1$
+$\mu$m in size, a quasi-single domain state can be realized with uniform
+anisotropy field. For larger patterned ferromagnetic thin-film elements, domain
+formation is thought to limit the effectiveness of shape anisotropy. In our
+work we show that very soft lithographically patterned Ni$_{80}$Fe$_{20}$ films
+with control of induced magnetic anisotropy can exhibit shape anisotropy fields
+in agreement with single-domain models, for both hysteresis loop measurements
+at low field and ferromagnetic resonance measurements at high field. We show
+the superiority of the fluxmetric form over the magnetometric form of
+anisotropy estimate for thin films with control dimensions from 10 $\mu$m to
+150 $\mu$m and in-plane aspect ratios above 10.",1210.5251v3
+2013-08-05,$π$ phase shift induced by interface anisotropy in precession of magnetization initiated by laser heating,"Laser-induced magnetization precession of a thick Pt/Co/Pt film with
+perpendicular interface anisotropy was studied using time resolved
+magneto-optical Kerr effect. Although the demagnetization energy dominates the
+interface anisotropy for the Co thickness considered, and the Co layer can be
+characterized by an effective easy-plane anisotropy, we found that an
+additional $\pi$ shift in the initial phase for the magnetization precession is
+needed to describe the measured data using only the effective easy-plane
+anisotropy. The additional $\pi$ phase is rendered by the dependence on the
+phonon temperature of the interface anisotropy, in contrast to the dependence
+on the electron temperature of the demagnetization energy. Our observation that
+the precession phase is affected by both the electron and phonon temperature
+warrants a detailed knowledge about the forms of anisotropy present in the
+system under investigation for a complete description of laser-induced
+magnetization precession.",1308.0976v5
+2013-09-05,A viable explanation of the CMB dipolar statistical anisotropy,"The presence of a dipolar statistical anisotropy in the spectrum of cosmic
+microwave background (CMB) fluctuations was reported by the Wilkinson Microwave
+Anisotropy Probe (WMAP), and has recently been confirmed in the Planck 2013
+analysis of the temperature anisotropies. At the same time, the Planck 2013
+results report a stringent bound on the amplitude of the local-type
+non-Gaussianity. We show that the non-linear effect of the dipolar anisotropy
+generates not only a quadrupole moment in the CMB but also a local-type
+non-Gaussianity. Consequently, it is not easy to build models having a large
+dipolar modulation and at the same time a sufficiently small quadrupole and
+level of local bispectral anisotropy to agree with the present data. In
+particular, most models proposed so far are almost excluded, or are at best
+marginally consistent with observational data. We present a simple alternative
+scenario that may explain the dipolar statistical anisotropy while satisfying
+the observational bounds on both the quadrupole moment and local-type
+non-Gaussianity.",1309.1350v2
+2013-12-26,Where is magnetic anisotropy field pointing to?,"The desired result of magnetic anisotropy investigations is the determination
+of value(s) of various anisotropy constant(s). This is sometimes difficult,
+especially when the precise knowledge of saturation magnetization is required,
+as it happens in ferromagnetic resonance (FMR) studies. In such cases we
+usually resort to `trick' and fit our experimental data to the quantity called
+\emph{anisotropy field}, which is strictly proportional to the ratio of the
+searched anisotropy constant and saturation magnetization. Yet, this quantity
+is scalar, simply a number, and is therefore of little value for modeling or
+simulations of the magnetostatic or micromagnetic structures. Here we show how
+to `translate' the values of magnetic anisotropy constants into the complete
+vector of magnetic anisotropy field. Our derivation is rigorous and covers the
+most often encountered cases, from uniaxial to cubic anisotropy.",1312.7130v1
+2014-09-11,Proton temperature-anisotropy-driven instabilities in weakly collisional plasmas: Hybrid simulations,"Kinetic instabilities in weakly collisional, high beta plasmas are
+investigated using two-dimensional hybrid expanding box simulations with
+Coulomb collisions modeled through the Langevin equation (corresponding to the
+Fokker-Planck one). The expansion drives a parallel or perpendicular
+temperature anisotropy (depending on the orientation of the ambient magnetic
+field). For the chosen parameters the Coulomb collisions are important with
+respect to the driver but are not strong enough to keep the system stable with
+respect to instabilities driven by the proton temperature anisotropy. In the
+case of the parallel temperature anisotropy the dominant oblique fire hose
+instability efficiently reduces the anisotropy in a quasilinear manner. In the
+case of the perpendicular temperature anisotropy the dominant mirror
+instability generates coherent compressive structures which scatter protons and
+reduce the temperature anisotropy. For both the cases the instabilities
+generate temporarily enough wave energy so that the corresponding (anomalous)
+transport coefficients dominate over the collisional ones and their properties
+are similar to those in collisionless plasmas.",1409.3407v1
+2015-06-10,Imprints of expansion onto the local anisotropy of solar wind turbulence,"We study the anisotropy of II-order structure functions defined in a frame
+attached to the local mean field in three-dimensional (3D) direct numerical
+simulations of magnetohydrodynamic turbulence, including or not the solar wind
+expansion. We simulate spacecraft flybys through the numerical domain by taking
+increments along the radial (wind) direction that forms an angle of $45^o$ with
+the ambient magnetic field. We find that only when expansion is taken into
+account, do the synthetic observations match the 3D anisotropy observed in the
+solar wind, including the change of anisotropy with scales. Our simulations
+also show that the anisotropy changes dramatically when considering increments
+oblique to the radial directions. Both results can be understood by noting that
+expansion reduces the radial component of the magnetic field at all scales,
+thus confining fluctuations in the plane perpendicular to the radial. Expansion
+is thus shown to affect not only the (global) spectral anisotropy, but also the
+local anisotropy of second-order structure functions by influencing the
+distribution of the local mean field, which enters this higher-order
+statistics.",1506.03450v1
+2015-07-17,Time evolution of the anisotropies of the hydrodynamically expanding sQGP,"In high energy heavy ion collisions of RHIC and LHC, a strongly interacting
+quark gluon plasma (sQGP) is created. This medium undergoes a hydrodynamic
+evolution, before it freezes out to form a hadronic matter. The initial state
+of the sQGP is determined by the initial distribution of the participating
+nucleons and their interactions. Due to the finite number of nucleons, the
+initial distribution fluctuates on an event-by-event basis. The transverse
+plane anisotropy of the initial state can be translated into a series of
+anisotropy coefficients or eccentricities: second, third, fourth-order
+anisotropy etc. These anisotropies then evolve in time, and result in
+measurable momentum-space anisotropies, to be measured with respect to their
+respective symmetry planes. In this paper we investigate the time evolution of
+the anisotropies. With a numerical hydrodynamic code, we analyze how the speed
+of sound and viscosity influence this evolution.",1507.05005v2
+2015-09-18,Three dimensional solar anisotropy of galactic cosmic rays near the recent solar minimum 23/24,"Three dimensional (3D) galactic cosmic ray (GCR) anisotropy has been studied
+for 2006- 2012. The GCR anisotropy, both in the ecliptic plane and in polar
+direction, were obtained based on the neutron monitors (NMs) and Nagoya muon
+telescopes (MT) data. We analyze two dimensional (2D) GCR anisotropy in the
+ecliptic plane and north-south anisotropy normal to the ecliptic plane. We
+reveal quasi-periodicities - the annual and 27-days waves in the GCR anisotropy
+in 2006-2012. We investigate the relationship of the 27-day variation of the
+GCR anisotropy in the ecliptic plane and in the polar direction with the
+parameters of solar activity and solar wind.",1509.05718v1
+2016-01-21,Multiscale model of global inner-core anisotropy induced by hcp-alloy plasticity,"$\bullet$ Multiscale model of inner-core anisotropy produced by hcp alloy
+deformation$\bullet$ 5 to 20% single-crystal elastic anisotropy and plastic
+deformation by pyramidal slip $\bullet$ Low-degree inner-core formation model
+with faster crystallization at the equatorThe Earth's solid inner-core exhibits
+a global seismic anisotropy of several percents. It results from a coherent
+alignment of anisotropic Fe-alloy crystals through the inner-core history that
+can be sampled by present-day seismic observations. By combining
+self-consistent polycrystal plasticity, inner-core formation models,
+Monte-Carlo search for elastic moduli, and simulations of seismic measurements,
+we introduce a multiscale model that can reproduce a global seismic anisotropy
+of several percents aligned with the Earth's rotation axis. Conditions for a
+successful model are an hexagonal-close-packed structure for the inner-core
+Fe-alloy, plastic deformation by pyramidal \textless{}c+a\textgreater{} slip,
+and large-scale flow induced by a low-degree inner-core formation model. For
+global anisotropies ranging between 1 and 3%, the elastic anisotropy in the
+single crystal ranges from 5 to 20% with larger velocities along the c-axis.",1601.05674v1
+2016-01-28,A New Maximum-Likelihood Technique for Reconstructing Cosmic-Ray Anisotropy at All Angular Scales,"The arrival directions of TeV-PeV cosmic rays show weak but significant
+anisotropies with relative intensities at the level of one per mille. Due to
+the smallness of the anisotropies, quantitative studies require careful
+disentanglement of detector effects from the observation. We discuss an
+iterative maximum-likelihood reconstruction that simultaneously fits cosmic ray
+anisotropies and detector acceptance. The method does not rely on detector
+simulations and provides an optimal anisotropy reconstruction for ground-based
+cosmic ray observatories located in the middle latitudes. It is particularly
+well suited to the recovery of the dipole anisotropy, which is a crucial
+observable for the study of cosmic ray diffusion in our Galaxy. We also provide
+general analysis methods for recovering large- and small-scale anisotropies
+that take into account systematic effects of the observation by ground-based
+detectors.",1601.07877v2
+2016-04-03,Spin relaxation signature of colossal magnetic anisotropy in platinum atomic chains,"Recent experimental data demonstrate emerging magnetic order in platinum
+atomically thin nanowires. Furthermore, an unusual form of magnetic anisotropy
+-- colossal magnetic anisotropy (CMA) -- was earlier predicted to exist in
+atomically thin platinum nanowires. Using spin dynamics simulations based on
+first-principles calculations, we here explore the spin dynamics of atomically
+thin platinum wires to reveal the spin relaxation signature of colossal
+magnetic anisotropy, comparing it with other types of anisotropy such as
+uniaxial magnetic anisotropy (UMA). We find that the CMA alters the spin
+relaxation process distinctly and, most importantly, causes a large speed-up of
+the magnetic relaxation compared to uniaxial magnetic anisotropy. The magnetic
+behavior of the nanowire exhibiting CMA should be possible to identify
+experimentally at the nanosecond time scale for temperatures below 5 K. This
+time-scale is accessible in e.g., soft x-ray free electron laser experiments.",1604.00626v1
+2017-01-02,Submicron scale tissue multifractal anisotropy in polarized light scattering,"A number of disordered systems exhibit local anisotropy in the fractal or
+multifractal correlation and in the resulting scaling behavior, which contain
+wealth of information on the system. Here, we demonstrate that the spatial
+dielectric fluctuations in a random medium like biological tissue exhibit such
+multifractal anisotropy, leaving its unique signature in the wavelength
+variation of the light scattering Mueller matrix and manifesting as an
+intriguing spectral diattenuation effect. We have thus developed an inverse
+analysis method for the quantification of the multifractal anisotropy from the
+scattering Mueller matrix. The method is based on processing the relevant
+Mueller matrix elements in Fourier domain using Born approximation followed by
+multifractal analysis. Application of this technique on tissues of human cervix
+ex vivo demonstrate the potential of the multifractal anisotropy parameters as
+novel biomarkers for screening subtle micro-structural changes associated with
+precancers. Sensing structural anisotropy in the sub-micron length scale via
+the multifractal anisotropy parameters may prove valuable for non-invasive
+characterization of a wide class of complex materials and disordered scattering
+media.",1701.00348v2
+2017-02-06,Higher-order anisotropies in the Blast-Wave Model - disentangling flow and density field anisotropies,"We formulate a generalisation of the blast-wave model which is suitable for
+the description of higher order azimuthal anisotropies of the hadron
+production. The model includes anisotropy in the density profile as well as an
+anisotropy in the transverse expansion velocity field. We then study how these
+two kinds of anisotropies influence the single-particle distributions and the
+correlation radii of two-particle correlation functions. Particularly we focus
+on the third-order anisotropy and consideration is given to the averaging over
+different orientation of the event plane.",1702.01735v2
+2017-03-03,Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope Data,"The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has
+collected the largest ever sample of high-energy cosmic-ray electron and
+positron events since the beginning of its operation. Potential anisotropies in
+the arrival directions of cosmic-ray electrons or positrons could be a
+signature of the presence of nearby sources. We use almost seven years of data
+with energies above 42 GeV processed with the Pass~8 reconstruction. The
+present data sample can probe dipole anisotropies down to a level of $10^{-3}$.
+We take into account systematic effects that could mimic true anisotropies at
+this level. We present a detailed study of the event selection optimization of
+the cosmic-ray electrons and positrons to be used for anisotropy searches.
+Since no significant anisotropies have been detected on any angular scale, we
+present upper limits on the dipole anisotropy. The present constraints are
+among the strongest to date probing the presence of nearby young and
+middle-aged sources.",1703.01073v1
+2017-11-04,Spin excitation anisotropy in optimal-isovalent-doped superconductor BaFe2(As0.7P0.3)2,"We use neutron polarization analysis to study spin excitation anisotropy in
+the optimal-isovalent-doped superconductor BaFe2(As0.7P0.3)2 (Tc = 30 K).
+Different from optimally hole and electron-doped BaFe2As2, where there is a
+clear spin excitation anisotropy in the paramagnetic tetragonal state well
+above Tc, we find no spin excitation anisotropy for energies above 2 meV in the
+normal state of BaFe2(As0.7P0.3)2. Upon entering the superconducting state,
+significant spin excitation anisotropy develops at the antiferromagnetic (AF)
+zone center QAF = (1, 0, L = odd), while magnetic spectrum is isotropy at the
+zone boundary Q = (1, 0, L = even). By comparing temperature, wave vector, and
+polarization dependence of the spin excitation anisotropy in BaFe2(As0.7P0.3)2
+and hole-doped Ba0.67K0.33Fe2As2 (Tc = 38 K), we conclude that such anisotropy
+arises from spin-orbit coupling and is associated with the nearby AF order and
+superconductivity.",1711.01497v1
+2018-04-19,Anisotropy of the DC conductivity due to orbital-selective spin fluctuations in the nematic phase of iron superconductors,"We study the dc conductivity of iron-based superconductors within the
+orbital-selective spin fluctuation scenario. Within this approach, the
+anisotropy of spin fluctuations below the spin-nematic transition at T$_S$ is
+also responsible for the orbital ordering, induced by nematic self-energy
+corrections to the quasiparticle dispersion. As a consequence, the anisotropy
+of the dc conductivity below T$_S$ is determined not only by the anisotropy of
+the scattering rates as expected within a spin-nematic scenario, but also by
+the modification of the Fermi velocity due to the orbital reconstruction. More
+interestingly, it turns out that these two effects contribute to the
+dc-conductivity anisotropy with opposite signs. By using realistic
+band-structure parameters we compute the conductivity anisotropy for both 122
+and FeSe compounds, discussing the possible origin of the different
+dc-conductivity anisotropy observed experimentally in these two families of
+iron-based superconductors.",1804.07293v4
+2018-10-09,Large nonvolatile control of magnetic anisotropy in CoPt by a ferroelectric ZnO-based tunneling barrier,"The electric control of magnetic anisotropy has important applications for
+nonvolatile memory and information processing. By first-principles
+calculations, we show a large nonvolatile control of magnetic anisotropy in
+ferromagnetic/ferroelectric CoPt/ZnO interface. Using the switched electric
+polarization of ZnO, the density-of-states and magnetic anisotropy at the CoPt
+surface show a large change. Due to a strong Co/Pt orbitals hybridization and a
+large spin-orbit coupling, a large control of magnetic anisotropy was found. We
+experimentally measured the change of effective anisotropy by tunneling
+resistance measurements in CoPt/Mg-doped ZnO/Co junctions. Additionally, we
+corroborate the origin of the control of magnetic anisotropy by observations on
+tunneling anisotropic magnetoresistance.",1810.03838v1
+2019-04-11,Fermi-Surface Selective Determination of the $\mathbf{g}$-Factor Anisotropy in URu$_2$Si$_2$,"The $g$-factor anisotropy of the heavy quasiparticles in the hidden order
+state of URu$_2$Si$_2$ has been determined from the superconducting upper
+critical field and microscopically from Shubnikov-de Haas (SdH) oscillations.
+We present a detailed analysis of the $g$-factor for the $\alpha$, $\beta$ and
+$\gamma$ Fermi-surface pockets. Our results suggest a strong $g$-factor
+anisotropy between the $c$ axis and the basal plane for all observed Fermi
+surface pockets. The observed anisotropy of the $g$-factor from the quantum
+oscillations is in good agreement with the anisotropy of the superconducting
+upper critical field at low temperatures, which is strongly limited by the
+paramagnetic pair breaking along the easy magnetization axis $c$. However, the
+anisotropy of the initial slope of the upper critical field near $T_c$ cannot
+be explained by the anisotropy of the effective masses and Fermi velocities
+derived from quantum oscillations.",1904.05567v1
+2019-05-13,Extraordinary temperature dependent magnetic anisotropy of the non-collinear antiferromagnet IrMn,"The magnetic anisotropy of antiferromagnets plays a crucial role in
+stabilising the magnetisation of many spintronic devices. In non-collinear
+antiferromagnets such as IrMn the symmetry and temperature dependence of the
+effective anisotropy are poorly understood. Theoretical and experimental
+calculations of the effective anisotropy constant for IrMn differ by two orders
+of magnitude, while the symmetry has been calculated as uniaxial in
+contradiction to the assumed relationship between crystallographic symmetry and
+temperature dependence of the anisotropy from the Callen-Callen law. In this
+letter we determine the effective anisotropy energy surface of \Lonetwo - \IrMn
+using an atomistic spin model and constrained Monte Carlo simulations. We find
+that meta-stable spin structures lower the overall energy barrier to a tenth of
+that estimated from simple geometrical considerations, significantly reducing
+the discrepancy between experiment and theory. The temperature scaling of the
+anisotropy energy barrier shows an exponent of \factor, close to a uniaxial
+exponent of 3. Our results demonstrate the importance of non-collinear spin
+states on the thermal stability of antiferromagnets with consequences for the
+practical application of antiferromagnets in devices operating at elevated
+temperatures.",1905.05069v1
+2020-01-10,Studying Anisotropy of Compressible Magnetohydrodynamic Turbulence by Synchrotron Polarization Intensity,"Based on statistical analysis of synchrotron polarization intensity, we study
+the anisotropic properties of compressible magnetohydrodynamic (MHD)
+turbulence. The second-order normalized structure function, quadrupole ratio
+modulus and anisotropic coefficient are synergistically used to characterize
+the anisotropy of the polarization intensity. On the basis of pre-decomposition
+data cubes, we first explore the anisotropy of the polarization intensity in
+different turbulence regimes and find that the most significant anisotropy
+occurs in the sub-Alfv\'enic regime. Using post-decomposition data cubes in
+this regime, we then study the anisotropy of the polarization intensity from
+Alfv\'en, slow and fast modes. Statistics of polarization intensity from
+Alfv\'en and slow modes demonstrate the significant anisotropy while statistics
+of polarization intensity from fast modes show isotropic structures, which is
+consistent with the earlier results provided in Cho & Lazarian (2002). As a
+result, both quadrupole ratio modulus and anisotropic coefficient for
+polarization intensities can quantitatively recover the anisotropy of
+underlying compressible MHD turbulence. The synergistic use of the two methods
+helps enhance the reliability of the magnetic field measurement.",2001.03276v1
+2020-01-20,The impact of anisotropy on ITER scenarios,"We report on the impact of anisotropy to tokamak plasma configuration and
+stability. Our focus is on analysis of the impact of anisotropy on ITER
+pre-fusion power operation 5~MA, $B=1.8$~T ICRH scenarios. To model ITER
+scenarios remapping tools are developed to distinguish the impact of pressure
+anisotropy from the change in magnetic geometry caused by an
+anisotropy-modified current profile. The remappings iterate the
+anisotropy-modified current profile to produce the same $q$ profile with
+matched thermal energy. The analysis is a step toward equilibria that are
+kinetically self-consistent for a prescribed scenario. We find characteristic
+detachment of flux surfaces from pressure surfaces, and an outboard (inboard)
+shift of peak density for $T_{\parallel}>T_\perp$ ( $T_{\parallel}<T_\perp$).
+Differences in the poloidal current profile are evident, albeit not as
+pronounced as for the spherical tokamak. We find that the incompressional
+continuum is largely unchanged in the presence of anisotropy, and the mode
+structure of gap modes is largely unchanged. The compressional branch however
+exhibits significant differences in the continuum. We report on the implication
+of these modifications.",2001.06996v1
+2022-02-15,Pressure and temperature dependence of fluorescence anisotropy of Green Fluorescent Protein,"We have studied the effect of high hydrostatic pressure and temperature on
+the steady state fluorescence anisotropy of Green Fluorescent Protein (GFP). We
+find that the fluorescence anisotropy of GFP at a constant temperature
+decreases with increasing pressure. At atmospheric pressure, anisotropy
+decreases with increasing temperature but exhibits a maximum with temperature
+for pressure larger than 20 MPa. The temperature corresponding to the maximum
+of anisotropy increases with increasing pressure. By taking into account of the
+rotational correlation time changes of GFP with the pressure-temperature
+dependent viscosity of the solvent, we argue that viscosity increase with
+pressure is not a major contributing factor to the decrease in anisotropy with
+pressure. Our results suggest that the decrease of fluorescence anisotropy with
+pressure may result from changes in H-bonding environment around the
+chromophore.",2202.07534v1
+2022-03-01,Driven Superconducting Vortex Dynamics in Systems with Two-Fold Anisotropy in the Presence of Pinning,"We examine the dynamics of superconducting vortices with two-fold anisotropic
+interaction potentials driven over random pinning and compare the behavior
+under drives applied parallel and perpendicular to the anisotropy direction.
+The number of topological defects reaches a maximum near depinning and then
+drops with increasing driving force as the vortices form one-dimensional
+chains. This coincides with a transition from a pinned nematic to a moving
+smectic aligned with the soft direction of the anisotropy. The system is
+generally more ordered when the drive is applied along the soft direction of
+the anisotropy, while for driving along the hard direction, there is a critical
+value of the anisotropy above which the system remains aligned with the soft
+direction. We also observe hysteresis in the dynamics, with one-dimensional
+aligned chains persisting during a decreasing drive sweep to drives below the
+threshold for chain formation during the increasing drive sweep. More
+anisotropic systems have a greater amount of structural disorder in the moving
+state. For lower anisotropy, the system forms a moving smectic-A state, while
+at higher anisotropy, a moving nematic state appears instead.",2203.00617v1
+2022-10-19,Generalised form of the magnetic anisotropy field in micromagnetic and atomistic spin models,"We present a general approach to the derivation of the effective anisotropy
+field which determines the dynamical behaviour of magnetic spins according to
+the Landau-Lifshitz-Gilbert equation. The approach is based on the gradient in
+spherical polar coordinates with the final results being expressed in Cartesian
+coordinates as usually applied in atomistic and micromagnetic model
+calculations. The approach is generally valid for all orders of anisotropies
+including higher order combinations of azimuthal and rotational anisotropies
+often found in functional magnetic materials such as permanent magnets and an
+emerging class of antiferromagnetic materials with applications in spintronics.
+Anisotropies are represented in terms of spherical harmonics which have the
+important property of rational temperature scaling. Effective field vectors are
+given for anisotropies up to sixth order, presenting a unified framework for
+implementing higher order magnetic anisotropies in numerical simulations.",2210.10916v4
+2022-12-27,Elastic anisotropy in heterogeneous materials,"Heterogeneous materials exhibit anisotropy to varying extent that is
+influenced by factors such as individual phase properties and microstructural
+configuration. A review of the existing anisotropy measures proposed in the
+context of single crystals reveal that they do not account for the material and
+microstructural descriptors influencing the extent of anisotropy in
+heterogeneous materials. To overcome this limitation, existing anisotropy
+indices have been re-interpreted by considering the effective elastic
+properties of heterogeneous materials obtained by appropriate homogenization
+techniques. Anisotropy quantification has been demonstrated considering two
+phase composite materials highlighting the role of constituent volume
+fractions, secondary phase shape and elastic contrast in influencing the extent
+of anisotropy. Specific cases leading to overall isotropy in two phase
+composite materials and extension of the approach to consider porosity and
+cracks have also been presented demonstrating the applicability of the approach
+to any class of heterogeneous materials thus filling a crucial gap in the
+existing literature.",2212.13503v3
+2023-03-21,Inducing or suppressing the anisotropy in multilayers based on CoFeB,"Controlling the uniaxial magnetic anisotropy is of practical interest to a
+wide variety of applications. We study Co$_{40}$Fe$_{40}$B$_{20}$ single films
+grown on various crystalline orientations of LiNbO$_3$ substrates and on
+oxidized silicon. We identify the annealing conditions that are appropriate to
+induce or suppress uniaxial anisotropy. Anisotropy fields can be increased by
+annealing up to 11 mT when using substrates with anisotropic surfaces. They can
+be decreased to below 1 mT when using isotropic surfaces. In the first case,
+the observed increase of the anisotropy originates from the biaxial strain in
+the film caused by the anisotropic thermal contraction of the substrate when
+back at room temperature after strain relaxation during annealing. In the
+second case, anisotropy is progressively removed by applying successive
+orthogonal fields that are assumed to progressively suppress any chemical
+ordering within the magnetic film. The method can be applied to CoFeB/Ru/CoFeB
+synthetic antiferromagnets but the tuning of the anisotropy comes with a
+decrease of the interlayer exchange coupling and a drastic change of the
+exchange stiffness.",2303.11718v1
+2024-01-01,Inverse anisotropic catalysis and complexity,"In this work the effect of anisotropy on computational complexity is
+considered by CA proposal in holographic two-sided black brane dual of a
+strongly coupled gauge theory. It is shown that due to
+confinement-deconfinement phase transition there are two different behaviors:
+by increase in anisotropy there would be an increase in complexity growth rate
+in small anisotropy and a decreases in the complexity growth rate in large
+anisotropy. In the extreme case the very large anisotropy leads to the unity of
+the complexity growth rate and complexity itself, it means that in this case
+getting the target state from the reference state is reachable by no effort.
+Moreover, we suggest that $\frac{1}{M}\frac{dC}{dt}$ is a better representation
+of system degrees of freedom rather than the complexity growth rate
+$\frac{dC}{dt}$ and show that how it is related to inverse anisotropic
+catalysis. In addition, we consider the one-sided black brane dual to the
+quantum quench and showed that increase in anisotropy comes with decrease in
+complexity regardless of the anisotropy value which is due to the fact that the
+system do not experience a phase transition.",2401.00732v1
+1998-01-05,Calculation of the Ostriker-Vishniac Effect in Cold Dark Matter Models,"We present a new derivation of the cosmic microwave background anisotropy
+spectrum from the Ostriker-Vishniac effect for an open, flat, or closed
+Universe, and calculate the anisotropy expected in cold dark-matter (CDM)
+models. We provide simple semi-analytic fitting formulas for the Vishniac power
+spectrum that can be used to evaluate the expected anisotropy in CDM models for
+any arbitrary ionization history. In a flat Universe, CDM models normalized to
+cluster abundances produce rms temperature anisotropies of 0.8--2.4 $\mu$K on
+arcminute angular scales for a constant ionization fraction of unity, whereas
+an ionization fraction of 0.2 yields rms anisotropies of 0.3--0.8 $\mu$K. In an
+open and/or high-baryon-density Universe, the level of anisotropy is somewhat
+higher. The signal in some of these models may be detectable with planned
+interferometry experiments. The damping of the acoustic peaks in the
+primary-anisotropy spectrum at degree angular scales depends primarily on the
+optical depth and only secondarily on the epoch of reionization. On the other
+hand, the amplitude of Ostriker-Vishniac anisotropies depends sensitively on
+the epoch of reionization. Therefore, when combined with the estimate of the
+reionization optical depth provided by maps of degree-scale anisotropies, the
+Ostriker-Vishniac effect can provide a unique probe of the epoch of
+reionization.",9801022v3
+2007-05-28,Dynamical models with a general anisotropy profile,"Both numerical simulations and observational evidence indicate that the outer
+regions of galaxies and dark matter haloes are typically mildly to
+significantly radially anisotropic. The inner regions can be significantly
+non-isotropic, depending on the dynamical formation and evolution processes. In
+an attempt to break the lack of simple dynamical models that can reproduce this
+behaviour, we explore a technique to construct dynamical models with an
+arbitrary density and an arbitrary anisotropy profile. We outline a general
+construction method and propose a more practical approach based on a
+parameterized anisotropy profile. This approach consists of fitting the density
+of the model with a set of dynamical components, each of which have the same
+anisotropy profile. Using this approach we avoid the delicate fine-tuning
+difficulties other fitting techniques typically encounter when constructing
+radially anisotropic models. We present a model anisotropy profile that
+generalizes the Osipkov-Merritt profile, and that can represent any smooth
+monotonic anisotropy profile. Based on this model anisotropy profile, we
+construct a very general seven-parameter set of dynamical components for which
+the most important dynamical properties can be calculated analytically. We use
+the results to look for simple one-component dynamical models that generate
+simple potential-density pairs while still supporting a flexible anisotropy
+profile. We present families of Plummer and Hernquist models in which the
+anisotropy at small and large radii can be chosen as free parameters. We also
+generalize these two families to a three-parameter family that
+self-consistently generates the set of Veltmann potential-density pairs.
+(Abridged...)",0705.4109v1
+2009-04-09,"Magnetic anisotropy in (Ga,Mn)As: Influence of epitaxial strain and hole concentration","We present a systematic study on the influence of epitaxial strain and hole
+concentration on the magnetic anisotropy in (Ga,Mn)As at 4.2 K. The strain was
+gradually varied over a wide range from tensile to compressive by growing a
+series of (Ga,Mn)As layers with 5% Mn on relaxed graded (In,Ga)As/GaAs
+templates with different In concentration. The hole density, the Curie
+temperature, and the relaxed lattice constant of the as-grown and annealed
+(Ga,Mn)As layers turned out to be essentially unaffected by the strain.
+Angle-dependent magnetotransport measurements performed at different magnetic
+field strengths were used to probe the magnetic anisotropy. The measurements
+reveal a pronounced linear dependence of the uniaxial out-of-plane anisotropy
+on both strain and hole density. Whereas the uniaxial and cubic in-plane
+anisotropies are nearly constant, the cubic out-of-plane anisotropy changes
+sign when the magnetic easy axis flips from in-plane to out-of-plane. The
+experimental results for the magnetic anisotropy are quantitatively compared
+with calculations of the free energy based on a mean-field Zener model. An
+almost perfect agreement between experiment and theory is found for the
+uniaxial out-of-plane and cubic in-plane anisotropy parameters of the as-grown
+samples. In addition, magnetostriction constants are derived from the
+anisotropy data.",0904.1565v1
+2012-03-22,Non-Parametric Approximations for Anisotropy Estimation in Two-dimensional Differentiable Gaussian Random Fields,"Spatially referenced data often have autocovariance functions with elliptical
+isolevel contours, a property known as geometric anisotropy. The anisotropy
+parameters include the tilt of the ellipse (orientation angle) with respect to
+a reference axis and the aspect ratio of the principal correlation lengths.
+Since these parameters are unknown a priori, sample estimates are needed to
+define suitable spatial models for the interpolation of incomplete data. The
+distribution of the anisotropy statistics is determined by a non-Gaussian
+sampling joint probability density. By means of analytical calculations, we
+derive an explicit expression for the joint probability density function of the
+anisotropy statistics for Gaussian, stationary and differentiable random
+fields. Based on this expression, we obtain an approximate joint density which
+we use to formulate a statistical test for isotropy. The approximate joint
+density is independent of the autocovariance function and provides conservative
+probability and confidence regions for the anisotropy parameters. We validate
+the theoretical analysis by means of simulations using synthetic data, and we
+illustrate the detection of anisotropy changes with a case study involving
+background radiation exposure data. The approximate joint density provides (i)
+a stand-alone approximate estimate of the anisotropy statistics distribution
+(ii) informed initial values for maximum likelihood estimation, and (iii) a
+useful prior for Bayesian anisotropy inference.",1203.5010v2
+2013-07-03,Self-Consistent Ion Cyclotron Anisotropy-Beta Relation for Solar Wind Protons,"We derive a set of self-consistent marginally stable states for a system of
+ion-cyclotron waves propagating parallel to the large-scale magnetic field
+through a homogeneous proton-electron plasma. The proton distributions and the
+wave dispersions are related through the condition that no further
+ion-cyclotron resonant particle scattering or wave growth/damping may take
+place. The thermal anisotropy of the protons in these states therefore defines
+the threshold value for triggering the proton-cyclotron anisotropy instability.
+A number of recent papers have noted that the anisotropy of solar wind protons
+at 1 AU does not seem to be limited by the proton-cyclotron anisotropy
+threshold, even at low plasma beta. However, this puzzle seems to be due solely
+to the estimation of this anisotropy threshold under the assumption that the
+protons have a bi-Maxwellian distribution. We note that bi-Maxwellian
+distributions are never marginally stable to the resonant cyclotron
+interaction, so these estimates do not represent physically valid thresholds.
+The threshold anisotropies obtained from our marginally stable states are much
+larger, as a function of proton parallel beta, than the bi-Maxwellian
+estimates, and we show that the measured data remains below these more rigorous
+thresholds. Thus, the results of this paper resolve the apparent contradiction
+presented by the solar wind anisotropy observations at 1 AU: The bi-Maxwellian
+anisotropies are not rigorous thresholds, and so do not limit the proton
+distributions in the solar wind.",1307.1059v1
+2013-07-25,Effects of anisotropy of turbulent convection in mean-field solar dynamo models,"We study how anisotropy of turbulent convection affects diffusion of
+large-scale magnetic fields and the dynamo process on the Sun. The effect of
+anisotropy is calculated in a mean-field magneto-hydrodynamics framework using
+the minimal $\tau$-approximation. We examine two types of mean-field dynamo
+models: the well-known benchmark flux-transport model, and a distributed-dynamo
+model with the subsurface rotational shear layer. For both models we
+investigate effects of the double-cell meridional circulation, recently
+suggested by helioseismology. We introduce a parameter of anisotropy as a ratio
+of the radial and horizontal intensity of turbulent mixing, to characterize the
+anisotropy effects. It is found that the anisotropy of turbulent convection
+affects the distribution of magnetic fields inside the convection zone. The
+concentration of the magnetic flux near the bottom and top boundaries of the
+convection zone is greater when the anisotropy is stronger. It is shown that
+the critical dynamo number and the dynamo period approach to constant values
+for the large anisotropy parameter. The anisotropy reduces the overlap of the
+toroidal fields of subsequent cycles in the time-latitude ``butterfly' diagram.
+If we assume that sunspots are formed in the vicinity of the subsurface shear
+layer, then the distributed dynamo model with anisotropic diffusivity satisfies
+the observational constraints from heloseismology results and is consistent
+with the value of effective turbulent diffusion, estimated from the dynamics of
+surface magnetic fields.",1307.6651v3
+2015-07-27,Interplay between effective mass anisotropy and Pauli paramagnetic effects in a multiband superconductor--Application to Sr2RuO4--,"We investigate the mixed state properties in a type II multiband
+superconductor with uniaxial anisotropy under the Pauli paramagnetic effects.
+Eilenberger theory extended to a multiband superconductor is utilized to
+describe the detailed vortex lattice properties, such as the flux line form
+factors, the vortex lattice anisotropy and magnetic torques. We apply this
+theory to Sr$_2$RuO$_4$ to analyze those physical quantities obtained
+experimentally, focusing on the interplay between the strong two-dimensional
+anisotropy and the Pauli paramagnetic effects. This study allows us to
+understand the origin of the disparity between the vortex lattice anisotropy
+($\sim$60) and the $H_{\rm c2}$ anisotropy ($\sim$20). Among the three bands;
+$\gamma$ with the effective mass anisotropy $\sim$180, $\alpha$ with $\sim$120,
+and $\beta$ with $\sim$60, the last one is found to be the major band,
+responsible for various magnetic responses while the minor $\gamma$ band plays
+an important role in the vortex formation. Namely, in a field orientation
+slightly tilted away from the two dimensional basal plane those two bands
+cooperatively form the optimal vortex anisotropy which exceeds that given by
+the effective mass formula with infinite anisotropy. This is observed by small
+angle neutron scattering experiments on Sr$_2$RuO$_4$. The pairing symmetry of
+Sr$_2$RuO$_4$ realized is either spin singlet or spin triplet with the d-vector
+strongly locked in the basal plane. The gap structure is that the major $\beta$
+band has a full gap and the minor $\gamma$ band has a $d_{x^2-y^2}$ like gap.",1507.07364v1
+2015-11-06,Velocity anisotropy in tidally limited star clusters,"We explore the long-term evolution of the anisotropy in the velocity space of
+star clusters starting with different structural and kinematical properties. We
+show that the evolution of the radial anisotropy strength and its radial
+variation within a cluster contain distinct imprints of the cluster initial
+structural properties, dynamical history, and of the external tidal field of
+its host galaxy. Initially isotropic and compact clusters with small initial
+values of the ratio of the half-mass to Jacobi radius, $r_h/r_J$, develop a
+strong radial anisotropy during their long-term dynamical evolution. Many
+clusters, if formed with small values of $r_h/r_J$, should now be characterized
+by a significant radial anisotropy increasing with the distance from the
+cluster centre, reaching its maximum at a distance between 0.2 $r_J$ and 0.4
+$r_J$, and then becoming more isotropic or mildly tangentially anisotropic in
+the outermost regions. A similar radial variation of the anisotropy can also
+result from an early violent relaxation phase. In both cases, as a cluster
+continues its evolution and loses mass, the anisotropy eventually starts to
+decrease and the system evolves toward an isotropic velocity distribution.
+However, in order to completely erase the strong anisotropy developed by these
+compact systems during their evolution, they must be in the advanced stages of
+their evolution and lose a large fraction of their initial mass. Clusters that
+are initially isotropic and characterized by larger initial values of
+$r_h/r_J$, on the other hand, never develop a significant radial anisotropy.",1511.02236v1
+2016-02-11,Ginzburg-Landau theory of the superheating field anisotropy of layered superconductors,"We investigate the effects of material anisotropy on the superheating field
+of layered superconductors. We provide an intuitive argument both for the
+existence of a superheating field, and its dependence on anisotropy, for
+$\kappa = \lambda / \xi$ (the ratio of magnetic to superconducting healing
+lengths) both large and small. On the one hand, the combination of our
+estimates with published results using a two-gap model for MgB${}_2$ suggests
+high anisotropy of the superheating field near zero temperature. On the other
+hand, within Ginzburg-Landau theory for a single gap, we see that the
+superheating field shows significant anisotropy only when the crystal
+anisotropy is large and the Ginzburg-Landau parameter $\kappa$ is small. We
+then conclude that only small anisotropies in the superheating field are
+expected for typical unconventional superconductors near the critical
+temperature. Using a generalized form of Ginzburg Landau theory, we do a
+quantitative calculation for the anisotropic superheating field by mapping the
+problem to the isotropic case, and present a phase diagram in terms of
+anisotropy and $\kappa$, showing type I, type II, or mixed behavior (within
+Ginzburg-Landau theory), and regions where each asymptotic solution is
+expected. We estimate anisotropies for a number of different materials, and
+discuss the importance of these results for radio-frequency cavities for
+particle accelerators.",1602.03752v3
+2016-04-20,Extending Velocity Channel Analysis for Studying Turbulence Anisotropies,"We extend the velocity channel analysis (VCA), introduced by Lazarian &
+Pogosyan, of the intensity fluctuations in the velocity slices of
+position-position-velocity (PPV) spectroscopic data from Doppler broadened
+lines to study statistical anisotropy of the underlying velocity and density
+that arises in a turbulent medium from the presence of magnetic field. In
+particular, we study analytically how the anisotropy of the intensity
+correlation in the channel maps changes with the thickness of velocity
+channels. In agreement with the earlier VCA studies we find that the anisotropy
+in the thick channels reflects the anisotropy of the density field, while the
+relative contribution of density and velocity fluctuations to the thin velocity
+channels depends on the density spectral slope. We show that the anisotropies
+arising from Alfven, slow and fast magnetohydrodynamical modes are different,
+in particular, the anisotropy in PPV created by fast modes is opposite to that
+created by Alfven and slow modes, and this can be used to separate their
+contributions. We successfully compare our results with the recent numerical
+study of the PPV anisotropies measured with synthetic observations. We also
+extend our study to the medium with self-absorption as well as to the case of
+absorption lines. In addition, we demonstrate how the studies of anisotropy can
+be performed using interferometers.",1604.06102v2
+2016-08-18,Anisotropies in the HI gas distribution toward 3C196,"The local Galactic HI gas was found to contain cold neutral medium (CNM)
+filaments that are aligned with polarized dust emission. These filaments appear
+to be dominated by the magnetic field and in this case turbulence is expected
+to show distinct anisotropies. We use the Galactic Effelsberg--Bonn HI Survey
+(EBHIS) to derive 2D turbulence spectra for the HI distribution in direction to
+3C196 and two more comparison fields. Prior to Fourier transform we apply a
+rotational symmetric 50% Tukey window to apodize the data. We derive average as
+well as position angle dependent power spectra. Anisotropies in the power
+distribution are defined as the ratio of the spectral power in orthogonal
+directions. We find strong anisotropies. For a narrow range in position angle,
+in direction perpendicular to the filaments and the magnetic field, the
+spectral power is on average more than an order of magnitude larger than
+parallel. In the most extreme case the anisotropy reaches locally a factor of
+130. Anisotropies increase on average with spatial frequency as predicted by
+Goldreich and Sridhar, at the same time the Kolmogorov spectral index remains
+almost unchanged. The strongest anisotropies are observable for a narrow range
+in velocity and decay with a power law index close to --8/3, almost identical
+to the average isotropic spectral index of $-2.9 < \gamma < -2.6$. HI
+filaments, associated with linear polarization structures in LOFAR observations
+in direction to 3C196, show turbulence spectra with marked anisotropies.
+Decaying anisotropies appear to indicate that we witness an ongoing shock
+passing the HI and affecting the observed Faraday depth.",1608.05369v3
+2017-01-23,Transference of Fermi Contour Anisotropy to Composite Fermions,"There has been a surge of recent interest in the role of anisotropy in
+interaction-induced phenomena in two-dimensional (2D) charged carrier systems.
+A fundamental question is how an anisotropy in the energy-band structure of the
+carriers at zero magnetic field affects the properties of the interacting
+particles at high fields, in particular of the composite fermions (CFs) and the
+fractional quantum Hall states (FQHSs). We demonstrate here tunable anisotropy
+for holes and hole-flux CFs confined to GaAs quantum wells, via applying
+\textit{in situ} in-plane strain and measuring their Fermi wavevector
+anisotropy through commensurability oscillations. For strains on the order of
+$10^{-4}$ we observe significant deformations of the shapes of the Fermi
+contours for both holes and CFs. The measured Fermi contour anisotropy for CFs
+at high magnetic field ($\alpha_\mathrm{CF}$) is less than the anisotropy of
+their low-field hole (fermion) counterparts ($\alpha_\mathrm{F}$), and closely
+follows the relation: $\alpha_\mathrm{CF} = \sqrt{\alpha_\mathrm{F}}$. The
+energy gap measured for the $\nu = 2/3$ FQHS, on the other hand, is nearly
+unaffected by the Fermi contour anisotropy up to $\alpha_\mathrm{F} \sim 3.3$,
+the highest anisotropy achieved in our experiments.",1701.06684v2
+2018-01-31,Anatomy of magnetic anisotropy induced by Rashba spin-orbit interactions,"Magnetic anisotropy controls the orientational stability and switching
+properties of magnetic states, and therefore plays a central role in
+spintronics. First-principles density-functional-theory calculations are able,
+in most cases, to provide a satisfactory description of bulk and interface
+contributions to the magnetic anisotropy of particular film/substrate
+combinations. In this paper we focus on achieving a simplified understanding of
+some trends in interfacial magnetic anisotropy based on a simple tight-binding
+model for quasiparticle states in a heavy-metal/ferromagnetic-metal bilayer
+film. We explain how to calculate the magnetic anisotropy energy of this model
+from the quasiparticle spin-susceptibility, compare with more conventional
+approaches using either a perturbative treatment of spin-orbit interactions or
+a direct calculation of the dependence of the energy on the orientation of the
+magnetization, and show that the magnetic anisotropy can be interpreted as a
+competition between a Fermi-sea term favoring perpendicular anisotropy and a
+Fermi-surface term favoring in-plane anisotropy. Based on this finding, we
+conclude that perpendicular magnetic anisotropy should be expected in an
+itinerant electron thin film when the spin magnetization density is larger than
+the product of the band exchange splitting and the Fermi level
+density-of-states of the magnetic state.",1801.10482v2
+2020-02-06,Temperature scaling of two-ion anisotropy in pure and mixed anisotropy systems,"Magnetic anisotropy plays an essential role in information technology
+applications of magnetic materials, providing a means to retain the long-term
+stability of a magnetic state in the presence of thermal fluctuations.
+Anisotropy consists of a single-ion contribution stemming from the crystal
+structure and two-ion terms attributed to the exchange interactions between
+magnetic atoms. A lack of robust theory crucially limits the understanding of
+the temperature dependence of the anisotropy in pure two-ion and mixed
+single-ion and two-ion systems. Here, we use Green's function theory and
+atomistic Monte Carlo simulations to determine the temperature scaling of the
+effective anisotropy in ferromagnets in these pure and mixed cases, from
+saturated to vanishing magnetization. At low temperature, we find that the pure
+two-ion anisotropy scales with the reduced magnetization as $k(m) \sim
+m^{2.28}$, while the mixed scenario describes the diversity of the temperature
+dependence of the anisotropy observed in real materials. The temperature
+dependence of the mixed anisotropy determined here is expected to considerably
+contribute to the understanding and the control of the thermal properties of
+magnetic materials.",2002.02548v2
+2020-03-20,"Anisotropy of the transport properties of NdFeAs(O,F) thin films grown on vicinal substrates","NdFeAs(O,F) thin films having different fluorine contents were grown on 5
+deg. or 10 deg. vicinal cut MgO and CaF2 single crystalline substrates by
+molecular beam epitaxy. Structural characterisations by reflection high-energy
+electron diffraction and x-ray diffraction confirmed the epitaxial growth of
+NdFeAs(O,F). The resistivities of the ab-plane and along the c-axis were
+derived from the resistivity measurements in the longitudinal and transversal
+directions. The c-axis resistivity was always higher than the ab-plane
+resistivity, resulting from the anisotropic electronic structure. The
+resistivity anisotropy at 300 K was almost constant in the range of 50-90
+irrespective of the F content. On the other hand, the resistivity anisotropy at
+56 K showed a strong fluorine dependence: the resistivity anisotropy was over
+200 for the films with optimum F contents (superconducting transition
+temperature Tc around 50 K), whereas the resistivity anisotropy was around 70
+for the films in the under-doped regime (Tc between 35 and 45 K). The mass
+anisotropy are the effective masses along the c-axis and on the ab-plane) close
+to Tc derived from the anisotropic Ginzburg-Landau approach using the
+angular-dependency of the ab-plane resistivity was in the range from 2 to 5. On
+the assumption that the square of the mass anisotropy is equal to the
+resistivity anisotropy, those values are small compared to the normal state
+anisotropy.",2003.09105v1
+2021-04-11,The Solar Cycle Variations of the Anisotropy of Taylor Scale and Correlation Scale in the Solar Wind Turbulence,"The field-aligned anisotropy of the solar wind turbulence, which is
+quantified by the ratio of the parallel to the perpendicular correlation (and
+Taylor) length scales, is determined by simultaneous two-point correlation
+measurements during the time period 2001-2017. Our results show that the
+correlation scale along the magnetic field is the largest, and the correlation
+scale in the field-perpendicular directions is the smallest, at both solar
+maximum and solar minimum. However, the Taylor scale reveals inconsistent
+results for different stages of the solar cycles. During the years 2001-2004,
+the Taylor scales are slightly larger in the field-parallel directions, while
+during the years 2004-2017, the Taylor scales are larger in the
+field-perpendicular directions. The correlation coefficient between the sunspot
+number and the anisotropy ratio is employed to describe the effects of solar
+activity on the anisotropy of solar wind turbulence. The results show that the
+correlation coefficient regarding the Taylor scale anisotropy (0.65) is larger
+than that regarding the correlation scale anisotropy (0.43), which indicates
+that the Taylor scale anisotropy is more sensitive to the solar activity. The
+Taylor scale and the correlation scale are used to calculate the effective
+magnetic Reynolds number, which is found to be systematically larger in the
+field-parallel directions than in the field-perpendicular directions. The
+correlation coefficient between the sunspot number and the magnetic Reynolds
+number anisotropy ratio is -0.75. Our results will be meaningful for
+understanding the solar wind turbulence anisotropy and its long-term
+variability in the context of solar activity.",2104.04920v1
+2021-12-23,Stress-tailoring magnetic anisotropy of V$_2$O$_3$/Ni bilayers,"We report on a temperature-driven reversible change of the in-plane magnetic
+anisotropy of V$_2$O$_3$/Ni bilayers. This is caused by the rhombohedral to
+monoclinic structural phase transition of V$_2$O$_3$ at $T_C$ = 160 K. The
+in-plane magnetic anisotropy is uniaxial above $T_C$, but as the bilayer is
+cooled through the structural phase transition, a secondary magnetic easy axis
+emerges. Ferromagnetic resonance measurements show that this change in magnetic
+anisotropy is reversible with temperature. We identify two structural
+properties of the V$_2$O$_3$/Ni bilayers affecting the in-plane magnetic
+anisotropy: (1) a growth-induced uniaxial magnetic anisotropy associated with
+step-like terraces in the bilayer microstructure and (2) a low-temperature
+strain-induced biaxial anisotropy associated with the V$_2$O$_3$ structural
+phase transition. Magnetoresistance measurements corroborate the change in
+magnetic anisotropy across the structural transition and suggest that the
+negative magnetostriction of Ni leads to the emergence of a strain-induced
+easy-axis. This shows that a temperature-dependent structural transition in
+V$_2$O$_3$ may be used to tune the magnetic anisotropy in an adjacent
+ferromagnetic thin film.",2112.12826v1
+2022-10-27,The influence of anisotropy on the evolution of interfacial morphologies in directional solidification: A phase-field study,"By adjusting the interface energy, curvature, and velocity, the anisotropy
+plays an important role in the interaction between interfacial processes and
+transport processes, determining the solidification structures. In this paper,
+through the quantitative phase-field model, the influence of anisotropy on the
+evolution of interfacial morphologies in directional solidification is
+investigated. To represent different interfacial anisotropies, the
+solidification processes with different preferred crystallographic orientations
+are performed. Then the effect of anisotropy on morphological evolution is
+discussed systematically. At the planar growth stage, the interfacial
+anisotropy makes no difference in the transport processes and morphological
+evolution. At the onset time of planar instability, the anisotropy determines
+the detailed evolution by adjusting the interface stiffness. At the
+planar-cellular-transition stage, with the influence of anisotropy, the
+interfacial curvature decreases from {\theta}0=0{\deg} to {\theta}0=40{\deg}.
+Hence, the solute concentration ahead of the interface increases from
+{\theta}0=0{\deg} to {\theta}0=40{\deg}, while the instantaneous velocity of
+the interface decreases from {\theta}0=0{\deg} to {\theta}0=40{\deg}. At the
+quasi-steady-state stage, the anisotropy determines the growth direction and
+tip velocity of the primary dendrite, as well as the onset of sidebranches.",2210.15673v1
+2023-04-15,Temperature-anisotropy conjugate magnon squeezing in antiferromagnets,"Quantum squeezing is an essential asset in the field of quantum science and
+technology. In this study, we investigate the impact of temperature and
+anisotropy on squeezing of quantum fluctuations in two-mode magnon states
+within uniaxial antiferromagnetic materials. Through our analysis, we discover
+that the inherent nonlinearity in these bipartite magnon systems gives rise to
+a conjugate magnon squeezing effect across all energy eigenbasis states, driven
+by temperature and anisotropy. We show that temperature induces amplitude
+squeezing, whereas anisotropy leads to phase squeezing. In addition, we observe
+that the two-mode squeezing characteristic of magnon eigenenergy states is
+associated with amplitude squeezing. This highlights the constructive impact of
+temperature and the destructive impact of anisotropy on two-mode magnon
+squeezing. Nonetheless, our analysis shows that the destructive effect of
+anisotropy is bounded. We demonstrate this by showing that, at a given
+temperature, the squeezing of the momentum (phase) quadrature (or equivalently,
+the stretching of the position (amplitude) quadrature) approaches a constant
+function of anisotropy after a finite value of anisotropy. Moreover, our study
+demonstrates that higher magnon squeeze factors can be achieved at higher
+temperatures, smaller levels of anisotropy, and closer to the Brillouin zone
+center. All these characteristics are specific to low-energy magnons in the
+uniaxial antiferromagnetic materials that we examine here.",2304.07602v2
+2023-09-18,Polarized anisotropic synchrotron emission and absorption and its application to Black Hole Imaging,"Low-collisionality plasma in a magnetic field generically develops anisotropy
+in its distribution function with respect to the magnetic field direction.
+Motivated by the application to radiation from accretion flows and jets, we
+explore the effect of temperature anisotropy on synchrotron emission. We derive
+analytically and provide numerical fits for the polarized synchrotron emission
+and absorption coefficients for a relativistic bi-Maxwellian plasma (we do not
+consider Faraday conversion/rotation). Temperature anisotropy can significantly
+change how the synchrotron emission and absorption coefficients depend on
+observing angle with respect to the magnetic field. The emitted linear
+polarization fraction does not depend strongly on anisotropy, while the emitted
+circular polarization does. We apply our results to black hole imaging of Sgr
+A* and M87* by ray-tracing a GRMHD simulation and assuming that the plasma
+temperature anisotropy is set by the thresholds of kinetic-scale
+anisotropy-driven instabilities. We find that the azimuthal asymmetry of the
+230 GHz images can change by up to a factor of 3, accentuating ($T_\perp >
+T_\parallel$) or counteracting ($T_\perp < T_\parallel$) the image asymmetry
+produced by Doppler beaming. This can change the physical inferences from
+observations relative to models with an isotropic distribution function, e.g.,
+by allowing for larger inclination between the line of sight and spin direction
+in Sgr A*. The observed image diameter and the size of the black hole shadow
+can also vary significantly due to plasma temperature anisotropy. We describe
+how the anisotropy of the plasma can affect future multi-frequency and photon
+ring observations. In Appendices we calculate kinetic anisotropy-driven
+instabilities (mirror, whistler, and firehose) for relativistically hot
+plasmas.",2309.10029v1
+1994-07-15,Temperature Anisotropies in a Universe with Global Defects,"We present a technique of calculating microwave anisotropies from global
+defects in a reionised universe. We concentrate on angular scales down to one
+degree where we expect the nongaussianity of the temperature anisotropy in
+these models to become apparent.",9407051v1
+1996-12-02,Coherence and Sakharov Oscillations in the Microwave Sky,"I discuss the origin of the ``Sakharov oscillations'' (or ``secondary Doppler
+peaks'') in standard angular power spectra of the Cosmic Microwave Background
+anisotropies calculated for inflationary models. I contrast this with the
+production of CMB anisotropies in `active' models and argue that the presence
+or absence of Sakharov oscillations will reveal fundamental properties of the
+primordial perturbations.",9612015v1
+2001-06-23,Interlayer pair tunneling and gap anisotropy in YBa$_2$Cu$_3$O$_{7-δ}$,"Recent ARPES measurement observed a large $ab$-axis gap anisotropy,
+$\Delta(0,\pi)/\Delta(\pi,0)=1.5$, in clean YBa$_2$Cu$_3$O$_{7-\delta}$. This
+indicates that some sub-dominant component may exist in the $d_{x^2-y^2}$-wave
+dominant gap. We propose that the interlayer pairing tunneling contribution can
+be determined through the investigation of the order parameter anisotropy.
+Their potentially observable features in transport and spin dynamics are also
+studied.",0106480v1
+2002-01-07,Temperature-dependent $H_{c2}$ anisotropy in MgB$_2$ as inferred from measurements on polycrystals,"We present data on temperature-dependent anisotropy of the upper critical
+field of MgB$_2$ obtained from the analysis of measurements on high purity, low
+resistivity polycrystals. The anisotropy decreases in a monotonic fashion with
+increase of temperature.",0201085v1
+2004-04-29,"Implications evinced by the phase diagram, anisotropy, magnetic penetration depths, isotope effects and conductivities of cuprate superconductors","Anisotropy, thermal and quantum fluctuations and their dependence on dopant
+concentration appear to be present in all cuprate superconductors, interwoven
+with the microscopic mechanisms responsible for superconductivity. Here we
+review anisotropy, in-plane and c-axis penetration depths, isotope effect and
+conductivity measurements to reassess the universal behavior of cuprates as
+revealed by the doping dependence of these phenomena and of the transition
+temperature.",0404702v1
+2002-09-24,Nano-constraints on the spatial anisotropy of the Gravitational Constant,"We present constraints from various experimental data that limit any spatial
+anisotropy of the Gravitational constant to less than a part per billion or
+even smaller. This rules out with a wide margin the recently reported claim of
+a spatial anisotropy of G with a diurnal temporal signature.",0209093v1
+2000-10-03,Isotropy vs anisotropy in small-scale turbulence,"The decay of large-scale anisotropies in small-scale turbulent flow is
+investigated. By introducing two different kinds of estimators we discuss the
+relation between the presence of a hierarchy for the isotropic and the
+anisotropic scaling exponents and the persistence of anisotropies. Direct
+measurements from a channel flow numerical simulation are presented.",0010006v1
+2006-05-16,Large-scale anisotropy in scalar turbulence,"The effect of anisotropy on the statistics of a passive tracer transported by
+a turbulent flow is investigated. We show that under broad conditions an
+arbitrarily small amount of anisotropy propagates to the large scales where it
+eventually dominates the structure of the concentration field. This result is
+obtained analytically in the framework of an exactly solvable model and
+confirmed by numerical simulations of scalar transport in two-dimensional
+turbulence.",0605033v1
+2004-05-19,Azimuthal anisotropy in high-energy heavy-ion collisions at RHIC energies,"Directed and elliptic event anisotropy parameters measured in the experiments
+at relativistic heavy-ion collider are presented. The possible origin of the
+measured elliptic anisotropy parameter $v_2$ and its sensitivity to the early
+phase of the high-energy heavy-ion collisions are discussed.",0405016v1
+2006-08-22,The effect of anisotropy and external magnetic filed on the thermal entanglement in a two-spin-qutrit system,"We study the thermal entanglement in a two-spin-qutrit system with anisotropy
+in the exchange coupling between two spins. We use the realignment criterion to
+distinguish the entangled states, and the negativity for measuring the
+entanglement in this system. We see that the anisotropy can provide an
+additional parameter for enhancing the entanglement.",0608169v1
+2008-02-01,"Rapid change of electronic anisotropy in overdoped (Y,Ca)Ba2Cu3O7-d","Electronic anisotropy was studied for overdoped (Y,Ca)Ba2Cu3O7-d with various
+doping levels (p). It was found that the pseudogap-like behavior in the
+resistivity disappear when p exceeds 0.17, independent of the oxygen
+deficiency. The anisotropy ratio (g) estimated from upper critical fields
+showed a rapid decrease at around p = 0.18, approaching g = 3 for p > 0.20.",0802.0061v1
+2008-07-07,Heisenberg antiferromagnets with uniaxial exchange and cubic anisotropies in a field,"Classical Heisenberg antiferromagnets with uniaxial exchange anisotropy and a
+cubic anisotropy term in a field on simple cubic lattices are studied with the
+help of ground state considerations and extensive Monte Carlo simulations.
+Especially, we analyze the role of non-collinear structures of biconical type
+occurring in addition to the well-known antiferromagnetic and spin-flop
+structures. Pertinent phase diagrams are determined, and compared to previous
+findings.",0807.1019v1
+2009-07-23,Heisenberg antiferromagnets with exchange and cubic anisotropies,"We study classical Heisenberg antiferromagnets with uniaxial exchange
+anisotropy and a cubic anisotropy term on simple cubic lattices in an external
+magnetic field using ground state considerations and extensive Monte Carlo
+simulations. In addition to the antiferromagnetic phase field--induced
+spin--flop and non--collinear, biconical phases may occur. Phase diagrams and
+critical as well as multicritical phenomena are discussed. Results are compared
+to previous findings.",0907.4173v1
+2010-11-13,Renormalization of the tunnel splitting in a rotating nanomagnet,"We study spin tunneling in a magnetic nanoparticle with biaxial anisotropy
+that is free to rotate about its anisotropy axis. Exact instanton of the
+coupled equations of motion is found that connects degenerate classical energy
+minima. We show that mechanical freedom of the particle renormalizes magnetic
+anisotropy and increases the tunnel splitting.",1011.3134v1
+2012-11-05,Multicritical points in the three-dimensional XXZ antiferromagnet with single-ion anisotropy,"The classical Heisenberg antiferromagnet with uniaxial exchange anisotropy,
+the XXZ model, and competing planar single-ion anisotropy in a magnetic field
+on a simple cubic lattice is studied with the help of extensive Monte Carlo
+simulations. The biconical (supersolid) phase, bordering the antiferromagnetic
+and spin-flop phases, is found to become thermally unstable well below the
+onset of the disordered, paramagnetic phase, leading to interesting
+multicritical points.",1211.1052v1
+2016-10-13,Development of Particle-in-Cell Simulation in a Two Dimensional Trench Geometry,"A two dimensional electrostatic Particle-in-Cell simulation code is developed
+to investigate anisotropy of ions in a trench geometry for plasma etching. The
+numerical simulation results suggest that if the trench width is larger than
+Debye length scale, anisotropy can be lost due to potential development across
+the trench. Furthermore, the effects of ion charge build up on the trench
+bottom is investigated, which can degrade the anisotropy.",1610.03918v1
+2020-11-25,Noncoplanar multiple-$Q$ spin textures by itinerant frustration: Effects of single-ion anisotropy and bond-dependent anisotropy,"We theoretically investigate multiple-$Q$ spin textures, which are composed
+of superpositions of spin density waves with different wave numbers, for an
+effective spin model of centrosymmetric itinerant magnets. Our focus is on the
+interplay between biquadratic interactions arising from the spin-charge
+coupling and magnetic anisotropy caused by the spin-orbit coupling. Taking into
+account two types of the magnetic anisotropy, single-ion anisotropy and
+bond-dependent anisotropy, we elucidate magnetic phase diagrams for an
+archetypal triangular-lattice system in the absence and presence of an external
+magnetic field. In the case of the single-ion anisotropy, we find a plethora of
+multiple-$Q$ instabilities depending on the strength and the sign of the
+anisotropy (easy plane or easy axis), including a skyrmion crystal with
+topological number of two. In an external magnetic field, we find that a
+skyrmion crystal with topological number of one is stabilized by the in-plane
+(out-of-plane) magnetic field under the easy-plane (easy-axis) anisotropy. We
+also examine the stability of the field-induced skyrmion crystal by rotating
+the field direction. As a biproduct, we show that a triple-$Q$ state with
+nonzero chirality appears in the presence of the biquadratic interaction and
+the easy-axis anisotropy. Meanwhile, we find that the bond-dependent anisotropy
+also stabilizes both types of skyrmion crystals. We show that, however, for the
+skyrmion crystal with topological number of one, Bloch- and N\'eel-type
+skyrmion crystals are selectively realized depending on the sign of the
+bond-dependent anisotropy. Moreover, we find yet another multiple-$Q$ states,
+including two types of meron crystals with the skyrmion numbers of one and two.
+The systematic investigation will provide a reference to complex magnetic
+textures in centrosymmetric magnetic metals.",2011.13040v2
+2021-04-22,Quasi-periodic changes of three dimensional solar anisotropy of galactic cosmic rays for 1965-2014,"We study features of the 3D anisotropy of galactic cosmic rays (GCR) for
+1965-2014. We analyze the 27-day variations of the 2D GCR anisotropy in the
+ecliptic plane, and the north-south anisotropy normal to the ecliptic plane. We
+study the dependence of the 27-day variation of the 3D GCR anisotropy on the
+solar cycle and solar magnetic cycle. We demonstrate that the 27-day variations
+of the GCR intensity and anisotropy can be used as an important tool to study
+solar wind, solar activity and heliosphere. We use the components of the 3D GCR
+anisotropy found based on hourly data of neutron monitors (NMs) and muon
+telescopes (MTs) using the harmonic analyses and spectrographic methods. We
+correct 2D diurnal variation of the GCR intensity for the influence of the
+Earth magnetic field. We derive the north-south component of the GCR anisotropy
+based on the GG index calculated as the difference in GCR intensities of Nagoya
+multidirectional MTs. We show that behavior of the 27-variation of the 3D
+anisotropy verifies an existence of a stable long-lived active heliolongitudes
+on the sun. This finding illustrates usefulness of the 27-day variation of the
+GCR anisotropy as a unique proxy to study solar wind, solar activity and
+heliosphere. We distinguish a tendency of the 22-year changes of the amplitudes
+of the 27-day variation of the 2D anisotropy connected with the solar magnetic
+cycle. We demonstrate that the amplitudes of the 27-day variation of the
+north-south component of the anisotropy vary upon the 11 year solar cycle,
+however, a dependence of the solar magnetic polarity hardly can be recognized.
+We show that the 27-day recurrences of the $GG$ index and At component are in a
+high positive correlation, and both are highly correlated with By component of
+the heliospheric magnetic field.",2104.11279v1
+2021-05-25,Study of Anisotropy on Ferromagnetic Electrodes of a Magnetic Tunnel Junction (MTJ)-Based Molecular Spintronics Device (MTJMSD),"Magnetic tunnel junction-based molecular spintronics devices (MTJMSDs) are
+designed by covalently connecting the paramagnetic molecules across two
+ferromagnets (FM) electrodes of a magnetic tunnel junction (MTJ). MTJMSD
+provides opportunities to connect FM electrodes of a vast range of anisotropy
+properties to a variety of molecules of length scale. Our prior studies showed
+that the paramagnetic molecules can produce strong antiferromagnetic coupling
+with FM electrodes. The device properties of MTJMSD depend upon various factors
+such as anisotropy, spin fluctuation, thermal energy, etc. In this paper, we
+report a theoretical Monte Carlo Simulation (MCS) study to explain the impact
+of anisotropy on the MTJMSD equilibrium properties. We studied the energy
+variation of the MTJMSD system with time as a function of FM electrode
+anisotropy. Experimentally designed FM electrodes of MTJMSD contain
+multi-layers of different ferromagnetic materials. These materials possess
+in-plane and out-of-plane magnetic anisotropy characteristics. To understand
+the competing effect of in-plane and out-of-plane anisotropy, we have
+computationally applied anisotropies on the left FM electrode. For the MCS
+study, the orientation of the device was kept along YZ plane. As a result, the
+applied anisotropy along the X-direction (\mathbit{A}_{\mathbit{Lx}}) and
+Y-direction (\mathbit{A}_{\mathbit{Ly}}) represent out-of-plane and in-plane
+anisotropy, respectively. We found that increasing anisotropy strength starts
+exhibiting diverse domain structures within an FM electrode. Increasing the
+magnitude of anisotropy was found to create stripe-shaped domains with opposite
+spins. These domains represent the different magnetic phases. However, the
+application of equal magnitude of in-plane and out-of-plane cancels the strip
+domain formation and lowers the magnetic moment of overall MTJMSD.",2105.11635v1
+2022-07-01,Extinction of the TeV Gamma-Ray Background by Sunlight,"I show that pair production on sunlight introduces a sizable anisotropy in
+the cosmic background of TeV gamma-rays. The anisotropy amplitude in the
+direction of the Sun exceeds the cosmic dipole anisotropy from the motion of
+the Sun relative to the cosmic rest-frame.",2207.00671v1
+1995-04-18,The Physics of Microwave Background Anisotropies,"Cosmic microwave background anisotropies provide a vast amount of information
+on both structure formation in the universe and the background dynamics and
+geometry. The full physical content and detailed structure of anisotropies can
+be understood in a simple and intuitive fashion through a systematic
+investigation of the individual mechanisms for anisotropy formation, based on
+elementary gravitational and fluid dynamics.",9504057v1
+1996-09-17,Results from the First Flight of BAM,"A new instrument, BAM (Balloon-borne Anisotropy Measurement), designed to
+measure cosmic microwave background (CMB) anisotropy at medium angular scales
+was flown for the first time in July of 1995. BAM is unique in that it uses a
+cryogenic differential Fourier transform spectrometer coupled to a lightweight
+off-axis telescope. The very successful first flight of BAM demonstrates the
+potential of the instrument for obtaining high quality CMB anisotropy data.",9609108v1
+1997-11-25,Microwave Background Anisotropy and Large Scale Structure in Warm Dark Matter Models,"Large scale structure and microwave background anisotropies are studied for
+warm dark matter models. Two warm dark matter candidates are considered:
+gravitinos and sterile neutrinos. Linear large scale structure properties such
+as $\sigma_{8}$ and the excess power are calculated, as well as microwave
+background anisotropies. A rather robust feature of warm dark matter models is
+that the large scale structure properties are similar to those of mixed dark
+matter, but that the microwave background anisotropy is very similar to that of
+standard cold dark matter.",9711304v1
+1998-06-01,Massless (pseudo-)scalar seeds of CMB anisotropy,"A primordial stochastic background of very weakly coupled massless
+(pseudo-)scalars can seed CMB anisotropy, when large-scale fluctuations of
+their stress-tensor re-enter the horizon during the matter-dominated era. A
+general relation between multipole coefficients of the CMB anisotropy and the
+seed's energy spectrum is derived. Magnitude and tilt of the observed
+anisotropies can be reproduced for the nearly scale-invariant axion spectra
+that are predicted in a particularly symmetric class of string cosmology
+backgrounds.",9806015v1
+1999-10-28,First Results from Viper: Detection of Small-Scale Anisotropy at 40 GHZ,"Results of a search for small-scale anisotropy in the cosmic microwave
+background (CMB) are presented. Observations were made at the South Pole using
+the Viper telescope, with a .26 degree (FWHM) beam and a passband centered at
+40 GHz. Anisotropy band-power measurements in bands centered at l = 108, 173,
+237, 263, 422 and 589 are reported. Statistically significant anisotropy is
+detected in all bands.",9910503v1
+2000-03-17,Non-Gaussian signature induced by the SZ effect of galaxy clusters,"We apply statistical tests, based on the study of thecoefficients in a
+wavelet decomposition, to a cosmological signal: the Cosmic Microwave
+Background (CMB) anisotropies. The latter represent the superposition of
+primary anisotropy imprints of the initial density perturbations and secondary
+anisotropies due to photon interactions after recombination. In an inflationary
+scenario with Gaussian distributed fluctuations, we study the statistical
+signature of the secondary effects. More specifically, we investigate the
+dominant effects arising from the Sunyaev-Zel'dovich effect of galaxy clusters.
+Our study predicts the non-Gaussian signature of these secondary anisotropies
+and its detectability in the context of the future CMB satellite Planck
+Surveyor.",0003256v1
+2001-05-19,The Imprint of Lithium Recombination on the Microwave Background Anisotropies,"Following Loeb (2001), we explore the imprint of the resonant 6708A line
+opacity of neutral lithium on the temperature and polarization anisotropies of
+the cosmic microwave background (CMB) at observed wavelengths of 250-350 micron
+(0.9-1.2 THz). We show that if lithium recombines in the redshift range of
+z=400-500 as expected, then the standard CMB anisotropies would be
+significantly modified in this wavelength band. The modified polarization
+signal could be comparable to the expected polarization anisotropies of the
+far-infrared background on sub-degree angular scales (l>100). Detection of the
+predicted signal can be used to infer the primordial abundance of lithium, and
+to probe structure in the Universe at z~500.",0105345v1
+2001-09-27,The theory of CMB anisotropies,"This is a review of the theory of CMB anisotropies, an updated version of a
+course given at the troisieme cycle de la Suisse Romande. An introduction to
+gauge invariant cosmological perturbation theory is given and the theory CMB
+anisotropies is develiped in this context. Simple analytical approximations for
+the acoustic peak positions for adiabatic and isocurvature perturbations are
+derived. Silk damping is discussed by an analytic approximation. A short
+description of the present status of observations and parameter estimation
+followed by a critical discussion terminate the review. The full system of
+differential equations for CMB anisotropies and polarization needed in a
+numerical treatment is also developed and given in an appendix.",0109522v1
+2002-03-07,TACMB-1: The Theory of Anisotropies in the Cosmic Microwave Background (Bibliographic Resource Letter),"This Resource Letter provides a guide to the literature on the theory of
+anisotropies in the cosmic microwave background. Journal articles, web pages,
+and books are cited for the following topics: discovery, cosmological origin,
+early work, recombination, general CMB anisotropy references, primary CMB
+anisotropies (numerical, analytical work), secondary effects,
+Sunyaev-Zel'dovich effect(s), lensing, reionization, polarization, gravity
+waves, defects, topology, origin of fluctuations, development of fluctuations,
+inflation and other ties to particle physics, parameter estimation, recent
+constraints, web resources, foregrounds, observations and observational issues,
+and gaussianity.",0203120v1
+2002-09-26,CMB observations using the SKA,"We examine the prospects for observations of CMB anisotropy with the SKA; we
+discuss the advantages of interferometric SKA imaging, observing strategies,
+calibration issues and the achievable sensitivity. Although the SKA will
+probably operate at cm wavelengths, where discrete source confusion dominates
+the CMB anisotropy, its extreme sensitivity to point sources will make it
+possible to subtract the source contamination at these wavelengths and thereby
+image the low surface brightness CMB anisotropies on small angular scales. The
+SKA, operating at 10-20 GHz, may usefully make high-l observations of the CMB
+anisotropy spectrum and survey the sky for Sunyaev-Zeldovich decrements.",0209569v1
+2004-06-24,Cosmic Background Radiation Mini-Review,"This is a complete re-write of the mini-review for the Review of Particle
+Physics (a.k.a the Partcicle Data Book), which includes an assessment of the
+CMB anisotropy results and their interpretation up until the end of 2003. It
+forms a compact overview of the field at this time. Sections headings are:
+Introduction; Description of CMB Anisotropies; Cosmological Parameters; Physics
+of Anisotropies; Current Anisotropy Data; CMB Polarization; Complications;
+Constraints on Cosmologies; Particle Physics Constraints; Fundamental Lessons;
+and Future Directions.",0406567v1
+2004-06-25,The Anisotropy of Electron MHD Turbulence,"We present numerical studies of 3-dimensional electron magnetohydrodynamic
+(EMHD) turbulence. We investigate cascade timescale and anisotropy of freely
+decaying strong EMHD turbulence with zero electron skin depth. Cascade time
+scales with $k^{-4/3}$. Our numerical results clearly show scale-dependent
+anisotropy. We discuss that the observed anisotropy is consistent with $k_{\|}
+\propto k_{\perp}^{1/3}$, where $k_{\|}$ and $k_{\perp}$ are wave numbers
+parallel and perpendicular to (local) mean magnetic field, respectively.",0406595v1
+2005-12-17,Light-cone anisotropy in 21cm fluctuations during the epoch of reionization,"The delay in light travel time along the line of sight generates an
+anisotropy in the power spectrum of 21cm brightness fluctuations from the epoch
+of reionization. We show that when the fluctuations in the neutral hydrogen
+fraction become non-linear at the later stages of reionization, the light-cone
+anisotropy becomes of order unity on scales >50 comoving Mpc. During this
+period the density fluctuations and the associated anisotropy generated by
+peculiar velocities are negligible in comparison.",0512453v2
+1994-02-04,Enhancement of Anisotropy due to Fluctuations in Quasi-One-Dimensional Antiferromagnets,"It is shown that the observed anisotropy of magnetization at high magnetic
+fields in RbMnBr3 , a quasi-one-dimensional antiferromagnet on a distorted
+stacked triangular lattice, is due to quantum and thermal fluctuations. These
+fluctuations are taken into account in the framework of linear spin-wave theory
+in the region of strong magnetic fields. In this region the divergent
+one-dimensional integrals are cut off by magnetic field and the bare easy-plane
+anisotropy. Logarithmical dependence on the cutoff leads to the ""enhancement""
+of the anisotropy in magnetization. Comparison between magnetization data and
+our theory with parameters obtained from neutron scattering experiments has
+been done.",9402024v1
+1998-05-19,Magnetic Anisotropy in Quantum Hall Ferromagnets,"We show that the sign of magnetic anisotropy energy in quantum Hall
+ferromagnets is determined by a competition between electrostatic and exchange
+energies. Easy-axis ferromagnets tend to occur when Landau levels whose states
+have similar spatial profiles cross. We report measurements of integer QHE
+evolution with magnetic-field tilt. Reentrant behavior observed for the $\nu =
+4$ QHE at high tilt angles is attributed to easy-axis anisotropy. This
+interpretation is supported by a detailed calculation of the magnetic
+anisotropy energy.",9805240v1
+2000-02-24,Numerical studies of domains and bubbles of Langmuir monolayers,"A numerical algorithm based on the finite element methods has been developed
+to accurately determine the shape of the boundary of a domain containing
+``boojum'' textures. Within the context of the simple model we adopt, the
+effects of both bulk elastic anisotropy and line-tension anisotropy on the
+domain boundary can be examined. It is found that line-tension anisotropy must
+be present in order to account for domains with protruding features. Both
+elastic anisotropy and anisotropic line-tension can result in domains with
+indentations. The numerical algorithm has been extended to investigate the
+problem of a bubble in extended region ordered phase.",0002367v1
+2000-12-03,Magnetic Anisotropy of a Single Cobalt Nanoparticle,"Using a new microSQUID set-up, we investigate magnetic anisotropy in a single
+1000-atoms cobalt cluster. This system opens new fields in the characterization
+and the understanding of the origin of magnetic anisotropy in such
+nanoparticles. For this purpose, we report three-dimensional switching field
+measurements performed on a 3 nm cobalt cluster embedded in a niobium matrix.
+We are able to separate the different magnetic anisotropy contributions and
+evidence the dominating role of the cluster surface.",0012029v1
+2001-03-01,Longitudinal and transversal piezoresistive response of granular metals,"In this paper, we study the piezoresistive response and its anisotropy for a
+bond percolation model of granular metals. Both effective medium results and
+numerical Monte Carlo calculations of finite simple cubic networks show that
+the piezoresistive anisotropy is a strongly dependent function of bond
+probability p and of bond conductance distribution width \Delta g. We find that
+piezoresistive anisotropy is strongly suppressed as p is reduced and/or \Delta
+g is enhanced and that it vanishes at the percolation thresold p=p_c. We argue
+that a measurement of the piezoresistive anisotropy could be a sensitive tool
+to estimate critical metallic concentrations in real granular metals.",0103035v1
+2002-05-01,Superconducting anisotropy and evidence for intrinsic pinning in single crystalline MgB$_2$,"We examine the superconducting anisotropy $\gamma_c = (m_c / m_{ab})^{1/2}$
+of a metallic high-$T_c$ superconductor MgB$_2$ by measuring the magnetic
+torque of a single crystal. The anisotropy $\gamma_c$ does not depend
+sensitively on the applied magnetic field at 10 K. We obtain the anisotropy
+parameter $\gamma_c = 4.31 \pm 0.14$. The torque curve shows the sharp
+hysteresis peak when the field is applied parallel to the boron layers. This
+comes from the intrinsic pinning and is experimental evidence for the
+occurrence of superconductivity in the boron layers.",0205010v1
+2002-06-10,Magnetic anisotropy of BaCu2Si2O7: theory and antiferromagnetic resonance,"Antiferromagnetic resonance (AFMR) of BaCu2Si2O7 and a microscopic theory of
+the magnetic anisotropy of spin 1/2 chain compounds with folded CuO3 geometry
+being in good agreement with the available data are presented. The AFMR studies
+at 4.2 K show the existence of two gaps (40 and 76 GHz) at zero magnetic field
+and of two spin re-orientation transitions for H||c. The microscopic origin of
+the two gaps is shown to be Hund's rule coupling which leads to a ""residual
+anisotropy"" beyond the compensation of the Dzyaloshinskii-Moriya term by the
+symmetric anisotropy which would be valid without Hund's coupling.",0206151v1
+2002-09-25,Crossed-anisotropy films for magnetic tunnel junctions and magnetic memory applications,"A prototype of magnetoresistive random access memory (MRAM) based on magnetic
+tunnel junctions (MTJ) was fabricated with crossed-anisotropy of magnetic
+layers on either side of the tunnelling barrier layer. It is demonstrated that
+the introduction of crossed-anisotropy results in smaller switching fields and
+better switching times compared to the conventional case of aligned
+anisotropies. The magnetoresistive properties of fabricated devices are in good
+agreement with the micromagnetic model.",0209578v1
+2002-11-14,Inhomogeneous States in a Small Magnetic Disk with Single-Ion Surface Anisotropy,"We investigate analytically and numerically the ground and metastable states
+for easy-plane Heisenberg magnets with single-ion surface anisotropy and disk
+geometry. The configurations with two half-vortices at the opposite points of
+the border are shown to be preferable for strong anisotropy. We propose a
+simple analytical description of the spin configurations for all values of a
+surface anisotropy. The effects of lattice pinning leads to appearance of a set
+of metastable configurations.",0211265v2
+2003-03-19,Many-body Green's function theory for thin ferromagnetic anisotropic Heisenberg films: treatment of the exchange anisotropy,"The many-body Green's function theory developed in our previous work for
+treating the reorientation of the magnetization of thin ferromagnetic films is
+extended to include the exchange anisotropy. This leads to additional momentum
+dependencies which require some non-trivial changes in the formalism. The
+theory is developed for arbitrary spin values S and for multilayers. The
+effects of the exchange anisotropy and the single-ion anisotropy, which was
+treated in our earlier work, on the magnetic properties of thin ferromagnetic
+films are compared.",0303389v1
+2003-07-16,Induced four fold anisotropy and bias in compensated NiFe/FeMn double layers,"A vector spin model is used to show how frustrations within a multisublattice
+antiferromagnet such as FeMn can lead to four-fold magnetic anisotropies acting
+on an exchange coupled ferromagnetic film. Possibilities for the existence of
+exchange bias are examined and shown to exist for the case of weak chemical
+disorder at the interface in an otherwise perfect structure. A sensitive
+dependence on interlayer exchange is found for anisotropies acting on the
+ferromagnet through the exchange coupling, and we show that a wide range of
+anisotropies can appear even for a perfect crystalline structure with an
+ideally flat interface.",0307384v1
+2003-11-17,Critical Hysteresis from Random Anisotropy,"Critical hysteresis in ferromagnets is investigated through a $N$-component
+spin model with random anisotropies, more prevalent experimentally than the
+random fields used in most theoretical studies. Metastability, and the
+tensorial nature of anisotropy, dictate its physics. Generically, random field
+Ising criticality occurs, but other universality classes exist. In particular,
+proximity to $\mathcal{O}(N)$ criticality may explain the discrepancy between
+experiment and earlier theories. The uniaxial anisotropy constant, which can be
+controlled in magnetostrictive materials by an applied stress, emerges as a
+natural tuning parameter.",0311393v2
+2003-11-20,Single-ion versus exchange anisotropy in calculating anisotropic susceptibilities of thin ferromagnetic Heisenberg films within many-body Green's function theory,"We compare transverse and parallel static susceptibilities of in-plane
+uniaxial anisotropic ferromagnetic Heisenberg films calculated in the framework
+of many-body Green's function theory using single-ion anisotropies with the
+previously investigated case of exchange anisotropies. On the basis of the
+calculated observables (easy and hard axes magnetizations and susceptibilities)
+no significant differences are found, i. e. it is not possible to propose an
+experiment that might decide which kind of anisotropy is acting in an actual
+ferromagnetic film.",0311482v1
+2004-01-26,"Evidence for granularity, anisotropy and lattice distortions in cuprate superconductors and their implications","Granularity, anisotropy, local lattice distortions and their dependence on
+dopant concentration appear to be present in all cuprate superconductors,
+interwoven with the microscopic mechanisms responsible for superconductivity.
+Here we review anisotropy and penetration depth measurements to reassess the
+evidence for granularity, as revealed by the notorious rounded phase
+transition, the evidence for the three dimensional nature of superconductivity,
+uncovered by the doping dependence of transition temperature and anisotropy,
+and to reassess the relevance of the electron-lattice coupling, emerging from
+the oxygen isotope effects.",0401505v1
+2004-04-30,In-Plane Conductivity Anisotropy in Underdoped Cuprates in the Spin-Charge Gauge Approach,"Applying the recently developed spin-charge gauge theory for the pseudogap
+phase in cuprates, we propose a self-consistent explanation of several peculiar
+features of the far-infrared in-plane AC conductivity, including a broad peak
+as a function of frequency and significant anisotropy at low temperatures,
+along with a similar temperature-dependent in-plane anisotropy of DC
+conductivity in lightly doped cuprates. The anisotropy of the metal-insulator
+crossover scale is considered to be responsible for these phenomena. The
+obtained results are in good agreement with experiments. An explicit proposal
+is made to further check the theory.",0404726v1
+2004-06-28,Critical properties of random anisotropy magnets,"The problem of critical behaviour of three dimensional random anisotropy
+magnets, which constitute a wide class of disordered magnets is considered.
+Previous results obtained in experiments, by Monte Carlo simulations and within
+different theoretical approaches give evidence for a second order phase
+transition for anisotropic distributions of the local anisotropy axes, while
+for the case of isotropic distribution such transition is absent. This outcome
+is described by renormalization group in its field theoretical variant on the
+basis of the random anisotropy model. Considerable attention is paid to the
+investigation of the effective critical behaviour which explains the
+observation of different behaviour in the same universality class.",0406692v1
+2004-07-07,Influence of surface anisotropy on the magnetization reversal of nanoparticles,"The influence of surface anisotropy on the magnetization processes of
+maghemite nanoparticles with ellipsoidal shape is studied by means of Monte
+Carlo simulations. Radial surface anisotropy is found to favor the formation of
+hedgehog-like spin structures that become more stable as the surface anisotropy
+constant at the surface $k_S$ is increased form the value at the core. We have
+studied the change in the low temperature hysteresis loops with the particle
+aspect ratio and with $k_S$, finding a change in the magnetization reversal
+mode as $k_S$ or the particle elongation is increased.",0407176v1
+2005-05-11,"Annealing-induced changes of the magnetic anisotropy of (Ga,Mn)As epilayers","The dependence of the magnetic anisotropy of As-capped (Ga,Mn)As epilayers on
+the annealing parameters - temperature and time - has been investigated. A
+uniaxial magnetic anisotropy is evidenced, whose orientation with respect to
+the crystallographic axes changes upon annealing from [-110] for the as-grown
+samples to [110] for the annealed samples. Both cubic an uniaxial anisotropies
+are tightly linked to the concentration of charge carriers, the magnitude of
+which is controlled by the annealing process.",0505278v1
+2005-12-02,Exchange enhanced anisotropy in ferromagnetic/antiferromagnetic multilayers: dynamic consequences,"The phenomena of exchange anisotropy is well known in terms of static
+magnetization properties such as enhanced coercivity and magnetization loop
+shifts. These effects are primarily associated with effective anisotropies
+introduced into the ferromagnet by exchange coupling with a strongly
+anisotropic antiferromagnet. These effective anisotropies can be understood as
+manifestations of a more fundamental exchange induced susceptibility. We show
+that a consequence of this view is that a class of unusual dynamic effects
+associated with the exchange susceptibility should also exist. The effects
+become apparent near the ordering temperature of the antiferromagnet and affect
+domain wall velocities, domain wall resonances, and precessional switching of
+the ferromagnet.",0512034v1
+2006-02-17,Theory of high-symmetry tetramer single molecule magnets,"We present a microscopic theory of single molecule magnets. From our exact
+single-ion spin matrix elements for four arbitrary spins, we study the
+single-ion anisotropy of equal spins exhibiting $T_d$, $D_{2d}$, or $C_{4v}$
+molecular group symmetry. Each group generates site-dependent single-ion
+anisotropy. For weak anisotropy, accurate Hartree expressions for the
+magnetization, specific heat, electron paramagnetic resonance (EPR) absorption,
+and inelastic neutron scattering cross-section are given. For $D_{2d}$,
+azimuthal single-ion anisotropy leads to the observed Ni$_4$ EPR splittings.",0602417v2
+2006-11-09,Phase diagram of the spin-1 XXZ Heisenberg ferromagnet with a single-ion anisotropy,"Phase diagram of the spin-1 quantum Heisenberg model with both exchange as
+well as single-ion anisotropy is constructed within the framework of pair
+approximation formulated as a variational procedure based on the
+Gibbs-Bogoliubov inequality. In this form adapted variational approach is used
+to obtain the results equivalent with the Oguchi's pair approximation. It is
+shown that the single-ion anisotropy induces a tricritical behaviour in the
+considered model system and a location of tricritical points is found in
+dependence on the exchange anisotropy strength.",0611254v3
+1997-12-19,Equilibrium of Spheres with Local Anisotropy in Postnewtonian Gravity. Application to White Dwarfs,"Static solutions of white dwarfs with spherical symmetry and local anisotropy
+are studied in the post-Newtonian approximation. It is argued that the
+condition for equilibrium must be that the total energy is a minimum for given
+baryon number and the question whether there is local isotropy or anisotropy
+inside the star should follow from that condition, rather than be postulated ""a
+priori"". It is shown show that, in post-Newtonian gravity, there are stable
+configurations with local anisotropy for masses above the Chandrasekhar limit.",9712081v1
+2001-08-29,Kaluza-Klein anisotropy in the CMB,"We show that 5-dimensional Kaluza-Klein graviton stresses can slow the decay
+of shear anisotropy on the brane to observable levels, and we use cosmic
+microwave background anisotropies to place limits on the initial anisotropy
+induced by these stresses. An initial shear to Hubble distortion of only \sim
+10^{-3}\Omega_0h_0^2 at the 5D Planck time would allow the observed large-angle
+CMB signal to be a relic mainly of KK tidal effects.",0108073v2
+2002-03-15,A method for analysing the jet azimuthal anisotropy in ultrarelativistic heavy ion collisions,"The azimuthal anisotropy of jet spectra due to energy loss of jet partons in
+azimuthally non-symmetric volume of dense quark-gluon matter is considered for
+semi-central nuclear interactions at collider energies. We develop the
+techniques for event-by-event analysing the jet azimuthal anisotropy using
+particle and energy elliptic flow, and suggest a method for calculation of
+coefficient of jet azimuthal anisotropy without reconstruction of nuclear
+reaction plane.",0203144v2
+1998-07-07,Event Anisotropy in High Energy Nucleus-Nucleus Collisions,"The predictions of event anisotropy parameters from transport model RQMD are
+compared with the recent experimental measurements for 158$A$ GeV Pb+Pb
+collisions. Using the same model, we study the time evolution of event
+anisotropy at 2$A$ GeV and 158$A$ GeV for several colliding systems. For the
+first time, both momentum and configuration space information are studied using
+the Fourier analysis of the azimuthal angular distribution. We find that, in
+the model, the initial geometry of the collision plays a dominant role in
+determining the anisotropy parameters.",9807021v1
+2007-08-11,Vorticity and Magnetic Field Generation from Initial Anisotropy in Ultrarelativistic Gamma-Ray Burst Blastwaves,"Because conical segments of quasispherical ultrarelativistic blastwaves are
+causally disconnected on angular scales larger than the blastwave inverse
+Lorentz factor, astrophysical blastwaves can sustain initial anisotropy,
+imprinted by the process that drives the explosion, while they remain
+relativistic. We show that initial angular energy fluctuations in
+ultrarelativistic blastwaves imply a production of vorticity in the blastwave,
+and calculate the vortical energy production rate. In gamma-ray burst (GRB)
+afterglows, the number of vortical eddy turnovers as the shocked fluid crosses
+the blastwave shell is about unity for marginally nonlinear anisotropy. Thus
+the anisotropy must be nonlinear to explain the magnetic energy density
+inferred in measured GRB spectra.",0708.1588v1
+2007-11-05,Polarization-anisotropy induced spatial anisotropy of polariton amplification in planar semiconductor microcavities,"Based on a microscopic many-particle theory we investigate the amplification
+of polaritons in planar semiconductor microcavities. We study a spatially
+perfectly isotropic microcavity system and excitation geometry. For this
+system, our analysis shows that a pump-induced vectorial polarization
+anisotropy can lead to a spatial anisotropy in the stimulated amplification of
+polaritons. This effect is brought about by the interplay of the
+longitudinal-transverse cavity mode splitting (TE-TM splitting) and the
+spin-dependence of the polariton-polariton scattering processes.",0711.0768v1
+2008-01-16,CMB Anisotropies: Their Discovery and Utilization,"This article is a written and modified version of a talk presented at the
+conference `A Century of Cosmology' held at San Servolo, Venice, Italy, in
+August 2007. The talk focuses on some of the cosmology history leading to the
+discovery and exploitation of Cosmic Microwave Background (CMB) Radiation
+anisotropies. We have made tremendous advances first in the development of the
+techniques to observe these anisotropies and in observing and interpreting them
+to extract their contained cosmological information. CMB anisotropies are now a
+cornerstone in our understanding of the cosmos and our future progress in the
+field. This is an outcome that Dennis Sciama hoped for and encouraged.",0801.2563v1
+2008-10-19,Magnetic anisotropy of single 3d spins on CuN surface,"First-principles calculations of the magnetic anisotropy energy for Mn- and
+Fe-atoms on CuN/Cu(001) surface are performed making use of the torque method.
+The easy magnetization direction is found to be different for Mn and Fe atoms
+in accord with the experiment. It is shown the magnetic anisotropy has a
+single-ion character and mainly originates from the local magnetic moment of
+Mn- and Fe-atoms. The uniaxial magnetic anisotropy constants are calculated in
+reasonable agreement with the experiment.",0810.3389v1
+2009-07-16,Galactic magnetic fields and the large-scale anisotropy at MILAGRO,"The air-shower observatory Milagro has detected a large-scale anisotropy of
+unknown origin in the flux of TeV cosmic rays. We propose that this anisotropy
+is caused by galactic magnetic fields, in particular, that it results from the
+combined effects of the regular and the turbulent (fluctuating) magnetic fields
+in our vicinity. Instead of a diffusion equation, we integrate Boltzmann's
+equation to show that the turbulence may define a preferred direction in the
+cosmic-ray propagation that is orthogonal to the local regular magnetic field.
+The approximate dipole anisotropy that we obtain explains well Milagro's data.",0907.2889v2
+2009-08-26,Magnetic anisotropy in Li-phosphates and origin of magnetoelectricity in LiNiPO4,"Li-based phosphates are paradigmatic materials for magnetoelectricity. By
+means of first-principles calculations, we elucidate the microscopic origin of
+spin anisotropy and of magnetoelectric effects in LiNiPO4. The comparison with
+LiCoPO4 reveals that Co-d7 and Ni-d8 electronic clouds show distinct orbital
+shapes, which in turn result in an opposite trend of the local spin anisotropy
+with respect to the surrounding O6 cages. Due to magnetic anisotropy, the
+Ni-based phosphate shows a peculiar ""angled-cross"" spin ground-state, which is
+responsible for magnetoelectricity. In this respect, we show that, under a
+magnetic field Hx, an electronic polarization Pz arises, with an estimated
+linear magneto-electric coefficient in good agreement with experiments.",0908.3802v1
+2010-02-10,Spin-orbit coupling induced anisotropy effects in bimetallic antiferromagnets: A route towards antiferromagnetic spintronics,"Magnetic anisotropy phenomena in bimetallic antiferromagnets Mn$_2$Au and
+MnIr are studied by first-principles density functional theory calculations. We
+find strong and lattice-parameter dependent magnetic anisotropies of the ground
+state energy, chemical potential, and density of states, and attribute these
+anisotropies to combined effects of large moment on the Mn 3$d$ shell and large
+spin-orbit coupling on the 5$d$ shell of the noble metal. Large magnitudes of
+the proposed effects can open a route towards spintronics in compensated
+antiferromagnets without involving ferromagnetic elements.",1002.2151v1
+2010-05-04,Cosmic Microwave Background Mini-review,"A compact overview of the status of CMB anisotropy results and their
+cosmological interpretation. Section headings: Introduction; CMB Spectrum;
+Description of CMB Anisotropies; Cosmological Parameters; Physics of
+Anisotropies; Current Anisotropy Data; CMB Polarization; Complications;
+Constraints on Cosmological Parameters; Particle Physics Constraints;
+Fundamental Lessons; and Future Directions. This 2023 replacement is a
+substantial update compared with earlier versions of this review posted to the
+arXiv.",1005.0555v2
+2010-08-19,Duality-based Asymptotic-Preserving method for highly anisotropic diffusion equations,"The present paper introduces an efficient and accurate numerical scheme for
+the solution of a highly anisotropic elliptic equation, the anisotropy
+direction being given by a variable vector field. This scheme is based on an
+asymptotic preserving reformulation of the original system, permitting an
+accurate resolution independently of the anisotropy strength and without the
+need of a mesh adapted to this anisotropy. The counterpart of this original
+procedure is the larger system size, enlarged by adding auxiliary variables and
+Lagrange multipliers. This Asymptotic-Preserving method generalizes the method
+investigated in a previous paper [arXiv:0903.4984v2] to the case of an
+arbitrary anisotropy direction field.",1008.3405v1
+2010-12-06,Anisotropies in the diffuse gamma-ray background measured by the Fermi-LAT,"The contribution of unresolved sources to the diffuse gamma-ray background
+could produce anisotropies in this emission on small angular scales. Recent
+studies have considered the angular power spectrum and other anisotropy metrics
+as tools for identifying contributions to diffuse emission from unresolved
+source classes, such as extragalactic and Galactic dark matter as well as
+various astrophysical gamma-ray source populations. We present preliminary
+results of an anisotropy analysis of the diffuse emission measured by the
+Fermi-LAT.",1012.1206v1
+2011-02-04,Anisotropy in transport and magnetic properties of K0.64Fe1.44Se2,"We report a study of anisotropy in transport and magnetic properties of
+K0.64Fe1.44Se2.00 single crystals. The anisotropy in resistivity is up to one
+order of magnitude between 1.8 K and 300 K. Magnetic susceptibility exhibits
+weak temperature dependence in the normal state with decrease in temperature
+with no significant anomalies. The lower critical fields Hc1 of
+K0.64Fe1.44Se2.00 are only about 3 Oe and the anisotropy of Hc1,c/Hc1,ab is
+about 1. The critical currents for H||ab and H||c are about 10-10^3 A/cm2,
+smaller than in iron pnictides and in FeTe_{1-x}Se_{x} and nearly isotropic.",1102.1010v3
+2011-02-17,The ordering of XY spin glasses,"Ordering properties of XY-like spin-glass magnets with an easy-plane magnetic
+anisotropy are studied based on a symmetry consideration and the results of
+recent numerical simulations on the pure Heisenberg and XY spin-glass models.
+The effects of an easy-plane-type uniaxial anisotropy, a random magnetic
+anisotropy and an applied magnetic field are investigated. In the XY regime in
+zero field, the ""spin-chirality decoupling"" persists even under the random
+magnetic anisotropy, escaping the ""spin-chirality recoupling"" phenomenon which
+inevitably occurs in the Heisenberg regime. Contrast between the scalar chiral
+order and the vector chiral order is emphasized. Implications to experiments
+are discussed.",1102.3496v1
+2011-05-31,Chemical order and size effects on the magnetic anisotropy of FePt and CoPt nanoparticles,"We investigate the consequence of the dimension reduction on the magnetic
+anisotropy of FePt and CoPt nanoparticles. Using an extension of the magnetic
+anisotropy model of N\'eel, we show that, due to a statistical finite size
+effect, chemically disordered clusters can display a magnetic anisotropy energy
+(MAE) as high as 0.5\times10^6 J/m3, more than one order of magnitude higher
+than the bulk MAE. Concerning L10 ordered clusters, we show that the surface
+induces a reduction of the MAE as compared to the bulk, due to the symmetry
+breaking at the cluster surface, which modifies the chemical order.",1105.6292v1
+2011-06-28,Anisotropies in the Gravitational-Wave Stochastic Background,"We consider anisotropies in the stochastic background of gravitational-waves
+(SBGW) arising from random fluctuations in the number of gravitational-wave
+sources. We first develop the general formalism which can be applied to
+different cosmological or astrophysical scenarios. We then apply this formalism
+to calculate the anisotropies of SBGW associated with the fluctuations in the
+number of cosmic string loops, considering both cosmic string cusps and kinks.
+We calculate the anisotropies as a function of angle and frequency.",1106.5555v2
+2011-08-31,Optical diode based on the one-way light-speed anisotropy,"We report that a triangular Fabry-Perot resonator filled with a parity-odd
+linear anisotropic medium exhibiting the one-way light speed anisotropy acts as
+a perfect diode. A Linear crystal such as the nematic liquid crystals whose
+molecular structures break parity can exhibit the one-way light speed
+anisotropy. The one-way light speed anisotropy also can be induced in a
+non-linear medium in the presence of constant electric and magnetic field
+strengths.",1108.6162v3
+2011-12-13,Phase Diagram of the mixed spin-2 and spin-5/2 Ising system with two different single-ion anisotropies,"In this paper we present a study of the effects of two different single-ion
+anisotropies in the phase diagram and in the compensation temperature of the
+mixed spin-2 and spin-5/2 Ising ferrimagnetic system. We employed the
+mean-field theory based on the Bogoliubov inequality for the Gibbs free energy.
+Also we found the Landau expansion of the free energy in the order parameter to
+describe the phase diagrams. In the plane critical temperature versus
+single-ion anisotropie the phase diagram displays tricritical behavior. The
+critical and compensation temperatures increase when the single-ion
+anisotropies increase.",1112.2989v1
+2012-04-11,On the large magnetic anisotropy of Fe_{2}P,"We present an investigation on the large magnetic anisotropy of Fe_{2}P,
+based on {\it Ab Initio} density-functional theory calculations, with a full
+potential linear muffin-tin orbital (FP-LMTO) basis. We obtain an uniaxial
+magnetic anisotropy energy (MAE) of 664 \mu eV/f.u., which is in decent
+agreement with experimental observations. Based on a band structure analysis
+the microscopical origin of the large magnetic anisotropy is explained. We also
+show that by straining the crystal structure, the MAE can be enhanced further.",1204.2419v2
+2012-10-02,Numerical resolution of an anisotropic non-linear diffusion problem,"This paper is devoted to the numerical resolution of an anisotropic
+non-linear diffusion problem involving a small parameter \varepsilon, defined
+as the anisotropy strength reciprocal. In this work, the anisotropy is carried
+by a variable vector function b. The equation being supplemented with Neumann
+boundary conditions, the limit \varepsilon \infty 0 is demonstrated to be a
+singular perturbation of the original diffusion equation. To address
+efficiently this problem, an Asymptotic-Preserving scheme is derived. This
+numerical method does not require the use of coordinates adapted to the
+anisotropy direction and exhibits an accuracy as well as a computational cost
+independent of the anisotropy strength.",1210.0681v1
+2012-10-09,Thermopower as sensitive probe of electronic nematicity in iron pnictides,"We study the in-plane anisotropy of the thermoelectric power and electrical
+resistivity on detwinned single crystals of isovalent substituted
+EuFe$_{2}$(As$_{1-x}$P$_{x}$)$_2$. Compared to the resistivity anisotropy the
+thermopower anisotropy is more pronounced and clearly visible already at
+temperatures much above the structural and magnetic phase transitions. Most
+remarkably, the thermopower anisotropy changes sign below the structural
+transition. This is associated with the interplay of two contributions due to
+anisotropic scattering and orbital polarization, which dominate at high- and
+low-temperatures, respectively.",1210.2634v2
+2013-02-12,Granular Brownian Motors: role of gas anisotropy and inelasticity,"We investigate the motion of a wedge-shaped object (a granular Brownian
+motor), which is restricted to move along the x-axis and cannot rotate, as gas
+particles collide with it. We show that its steady-state drift, resulting from
+inelastic gas-motor collisions, is dramatically affected by anisotropy in the
+velocity distribution of the gas. We identify the dimensionless parameter
+providing the dependence of this drift on shape, masses, inelasticity, and
+anisotropy: the anisotropy leads to a dramatic breaking of equipartition, which
+should easily be visible in experimental realizations.",1302.2877v2
+2013-05-07,Local control of single atom magneto-crystalline anisotropy,"Individual Fe atoms on a Cu2N/Cu(100) surface exhibit strong magnetic
+anisotropy due to the crystal field. Using atom manipulation in a
+low-temperature STM we demonstrate that the anisotropy of one Fe atom is
+significantly influenced by local strain due to a second Fe atom placed nearby.
+Depending on the relative positions of the two atoms on the Cu2N lattice we can
+controllably enhance or reduce the uniaxial anisotropy. We present a model that
+explains the observed behavior qualitatively in terms of first principles.",1305.1616v2
+2013-06-03,Non-Bunch-Davies Anisotropy,"We introduce a generic mechanism that can extend the effects of relic
+anisotropies at the beginning of inflation to relatively much shorter scales in
+density perturbations. This is induced by non-Bunch-Davies states of the
+quantum fluctuations, and can show up in the non-oscillatory components of the
+density perturbations. This mechanism works for general forms of anisotropies,
+and, to illustrate it, we use an example of relic vector field. The detailed
+scale-dependence of these anisotropies can be used to probe the initial quantum
+state of our universe.",1306.0609v1
+2013-06-11,Incompressible States of Dirac Fermions in Graphene with Anisotropic Interactions,"We report on the properties of incompressible states of Dirac fermions in
+graphene in the presence of anisotropic interactions and a quantizing magnetic
+field. We introduce the necessary formalism to incorporate the anisotropy in
+the system. The incopmpressible state in graphene is found to survive the
+anisotropy upto a critical value of the anisotropy parameter. The anisotropy
+also introduces two branches in the collective excitations of the corresponding
+Laughlin state. It strongly influences the short-range behavior of the
+pair-correlation functions in the incompressible ground state.",1306.2408v1
+2013-06-29,Perpendicular magnetization of Co20Fe50Ge30 films induced by MgO interface,"Epitaxial growth of Co20Fe50Ge30 thin film on single crystal MgO (001)
+substrate is reported. Structure characterization revealed (001)-oriented B2
+order of CoFeGe well lattice matched with the MgO barrier. Perpendicular
+magnetic anisotropy (PMA) was achieved in the MgO/CoFeGe/MgO structure with an
+optimized magnetic anisotropy energy density (K) of 3 106 erg/cm3. The magnetic
+anisotropy is found to depend strongly on the thickness of the MgO and CoFeGe
+layers, indicating that the PMA of CoFeGe is contributed by the interfacial
+anisotropy between CoFeGe and MgO. With reported low damping constant, CoFeGe
+films are promising spintronic materials for achieving low switching current.",1307.0104v1
+2014-04-02,Perpendicular magnetic anisotropy of cobalt films intercalated under graphene,"Magnetic properties of nanometer thick Co films intercalated at the
+graphene/Ir(111) interface are investigated using spin-polarized low-energy
+electron microscopy (SPLEEM) and Auger electron spectroscopy. We show that the
+graphene top layer promotes perpendicular magnetic anisotropy in the Co film
+underneath, even for relatively thick intercalated deposits. The magnetic
+anisotropy energy is significantly larger for the graphene/Co interface than
+for the free Co surface. Hybridization of the graphene and Co electron orbitals
+is believed to be at the origin of the observed perpendicular magnetic
+anisotropy.",1404.0705v1
+2014-05-11,Tuning perpendicular magnetic anisotropy in the MgO/CoFeB/Ta thin films,"Understanding the magnetic anisotropy at ferromagnetic metal/oxide interface
+is a fundamental and intriguing subject. Here we propose an approach to
+manipulate the strength of perpendicular magnetic anisotropy (PMA) by varying
+MgO thickness in the MgO/CoFeB/Ta thin films. We identify that the PMA at the
+MgO/CoFeB interface is tuned by the crystalline structure of bulk MgO layer and
+decreases dramatically due to the onset of crystalline MgO forming with the
+increase of MgO thickness. Our work opens an avenue to manipulate the magnetic
+anisotropy by the modification of the ferromagnetic metal/oxide interface.",1405.2551v2
+2014-05-16,Statistical Anisotropies in Gravitational Waves in Solid Inflation,"Solid inflation can support a long period of anisotropic inflation. We
+calculate the statistical anisotropies in the scalar and tensor power spectra
+and their cross-correlation in anisotropic solid inflation. The tensor-scalar
+cross-correlation can either be positive or negative, which impacts the
+statistical anisotropies of the TT and TB spectra in CMB map more significantly
+compared with the tensor self-correlation. The tensor power spectrum contains
+potentially comparable contributions from quadrupole and octopole angular
+patterns, which is different from the power spectra of scalar, the
+cross-correlation or the scalar bispectrum, where the quadrupole type
+statistical anisotropy dominates over octopole.",1405.4179v1
+2014-09-16,On the anisotropy of stress-distribution induced in glasses and crystals by non-ablative femtosecond laser exposure,"Femtosecond laser exposure in the non-ablative regime induces a variety of
+bulk structural modifications, in which anisotropy may depend on the
+polarization of the writing beam. In this work, we investigate the correlation
+between polarization state and stress anisotropy. In particular, we introduce a
+methodology that allows for rapid analysis and visualization of laser-induced
+stress anisotropy in glasses and crystals. Using radial and azimuthal
+polarization, we also demonstrate stress states that are nearly isotropic.",1409.4578v1
+2015-06-23,Effects of magnetic anisotropy on spin dynamics of ferromagnetic frustrated chain,"By exploiting density-matrix renormalization group techniques, we investigate
+the spin dynamics of a spin-1/2 one-dimensional J1-J2 XXZ model with competing
+ferromagnetic J1 and antiferromagnetic J2 exchange couplings under applied
+magnetic fields. Numerical results of spin excitation spectra show that in the
+field-induced spin quadrupole regime, the longitudinal component has a gapless
+mode and the transverse component has a gapped mode irrespective of the
+exchange anisotropy. The excitation gap of the transverse spin excitation
+increases as the exchange anisotropy increases over the XY-like and Ising-like
+regions, demonstrating that two-magnon bound states are stabilized due to the
+easy-axis anisotropy.",1506.06883v1
+2015-11-30,Mobility anisotropy in monolayer black phosphorus due to charged impurities,"We study the charged impurity limited mobility in black phosphorus, a highly
+anisotropic layered material. We compute the mobility within the Boltzmann
+transport equation under detailed balance condition, and taking into account
+the anisotropy in transport and electronic structure. For carrier densities
+accessible in experiments, we obtained an anisotropy ratio of 3 ~ 4 at zero
+temperature, two-folds larger than that observed in experiments on multilayers
+samples. We discuss also how the anisotropy depends on carrier density and
+impurity distribution.",1511.09151v1
+2015-12-22,Orbit anisotropy of dark matter haloes with Schwarzschild modelling,"We apply the Schwarzschild orbit superposition method to mock data in order
+to investigate the accuracy of recovering the profile of the orbit anisotropy.
+The mock data come from four numerical realizations of dark matter haloes with
+well defined anisotropy profiles. We show that when assuming a correct mass
+distribution we are able to determine the anisotropy with high precision and
+clearly distinguish between the models.",1512.07266v1
+2015-12-29,Solitary structures with ion and electron thermal anisotropy,"Formation of electrostatic solitary structures are analysed for a magnetised
+plasma with ion and electron thermal anisotropies. The ion thermal anisotropy
+is modelled with the help of the Chew-Goldberger-Low (CGL) double adiabatic
+equations of state while the electrons are treated as inertia-less species with
+an anisotropic bi-Maxwellian velocity distribution function. A negative
+electron thermal anisotropy $(T_{e\perp}/T_e{\parallel}>1)$ is found to help
+form large amplitude solitary structures which are in agreement with
+observational data.",1512.08633v1
+2016-02-03,Anisotropy in broad component of H$α$ line in the magnetospheric device RT-1,"Temperature anisotropy in broad component of H$\alpha$ line was found in the
+ring trap 1 (RT-1) device by Doppler spectroscopy. Since hot hydrogen neutrals
+emitting a broad component are mainly produced by charge exchange between
+neutrals and protons, the anisotropy in the broad component is the evidence of
+proton temperature anisotropy generated by betatron acceleration.",1602.01165v1
+2016-04-18,Phase field modelling of interfacial anisotropy driven faceting of precipitates,"We use extended Cahn-Hilliard (ECH) equations to study faceted precipitate
+morphologies; specifically, we obtain four sided precipitates (in 2-D) and
+dodecahedron (in 3-D) in a system with cubic anisotropy, and, six-sided
+precipitates (in 2-D, in the basal plane), hexagonal dipyramids and hexagonal
+prisms (in 3-D) in systems with hexagonal anisotropy. Our listing of these ECH
+equations is fairly comprehensive and complete (upto sixth rank tensor terms of
+the Taylor expansion of the free energy). We also show how the parameters that
+enter the model are to be obtained if either the interfacial energy anisotropy
+or the equilibrium morphology of the precipitate is known.",1604.05208v1
+2016-05-17,Effects of spin fluctuation on the magnetic anisotropy constant of itinerant electron magnets,"In the disordered local moment picture, we calculated the magnetization (M)
+and magnetic anisotropy energy (MAE) of FePt, CoPt, and MnAl ordered alloys and
+body-centered tegragonal FeCo (bct-FeCo) disordered alloy, assuming spatially
+fluctuated spin configurations at finite temperatures. All alloys exhibit the
+relation K1(T)/K1(0)=(M(T)/M(0))^n with the exponent (n) around 2. This is
+consistent with the two-ion anisotropy model, in contrast to the usual
+single-ion anisotropy model exhibiting n=3. Because these systems have
+different mechanisms of MAE, we suggest that this relation is a general rule
+for itinerant electron systems.",1605.05058v1
+2016-06-08,Magnetic energy of sc ferromagnetic films with three layers as described by third order perturbed Heisenberg Hamiltonian,"The solution of third order perturbed Heisenberg Hamiltonian of simple cubic
+ferromagnetic ultra-thin films with three layers were found. All the magnetic
+energy parameters such as spin exchange interaction, magnetic dipole
+interaction, second order magnetic anisotropy, fourth order magnetic
+anisotropy, applied magnetic field, demagnetization factor and stress induced
+anisotropy were included in the third order perturbed Heisenberg Hamiltonian.
+3-D plots of stress induced anisotropy, out of plane magnetic field,
+demagnetization factor and spin exchange interaction are presented in this
+manuscript. Magnetic easy and hard directions were determined using these 3-D
+plots. MATLAB program was employed to solve the equation with seven parameters.",1606.02439v1
+2016-09-26,Anisotropies of Gravitational Wave Backgrounds: A Line Of Sight Approach,"In the weak field regime, gravitational waves can be considered as being made
+up of collisionless, relativistic tensor modes that travel along null geodesics
+of the perturbed background metric. We work in this geometric optics picture to
+calculate the anisotropies in gravitational wave backgrounds resulting from
+astrophysical and cosmological sources. Our formalism yields expressions for
+the angular power spectrum of the anisotropies. We show how the anisotropies
+are sourced by intrinsic, Doppler, Sachs-Wolfe, and Integrated Sachs-Wolfe
+terms in analogy with Cosmic Microwave Background photons.",1609.08168v1
+2016-10-18,Engineering Curvature Induced Anisotropy in Thin Ferromagnetic Films,"The large curvature effects on micromagnetic energy of a thin ferromagnetic
+film with nonlocal dipolar energy are considered. We predict that the dipolar
+interaction and surface curvature can produce perpendicular anisotropy which
+can be controlled by engineering a special type of periodic surface shape
+structure. Similar effects can be achieved by a significant surface roughness
+in the film. We show that in general the anisotropy can point in an arbitrary
+direction depending on the surface curvature. We provide simple examples of
+these periodic surface structures to demonstrate how to engineer particular
+anisotropies in the film.",1610.05574v1
+2017-04-18,Quantitative analysis of the influence of keV He ion bombardment on exchange bias layer systems,"The mechanism of ion bombardment induced magnetic patterning of exchange bias
+layer systems for creating engineered magnetic stray field landscapes is still
+unclear. We compare results from vectorial magneto-optic Kerr effect
+measurements to a recently proposed model with time dependent rotatable
+magnetic anisotropy. Results show massive reduction of rotational magnetic
+anisotropy compared to all other magnetic anisotropies. We disprove the
+assumption of comparable weakening of all magnetic anisotropies and show that
+ion bombardment mainly influences smaller grains in the antiferromagnet.",1704.05487v1
+2017-06-29,The sign of the polarizability anisotropy of polar molecules is obtained faithfully from terahertz Kerr effect,"Optically heterodyned detected terahertz Kerr effect of gases of polar
+molecules is reported. Strikingly, the birefringence signal from fluoroform is
+found to have opposite polarity compared to water and acetonitrile. This
+behavior is a hallmark of the opposite sign of the polarizability anisotropy of
+these molecules. Resonant excitation of the rotational degrees of freedom of
+the molecules aligns their permanent dipoles along the terahertz electric
+field. This alignment is translated into an optical birefringence through the
+polarizability anisotropy of each molecule. Therefore, the resulting net signal
+scales with the polarizability anisotropy, whose sign is imprinted faithfully
+onto the transient birefringence signal.",1706.09623v1
+2017-07-20,General kinetic solution for the Biermann battery with an associated pressure anisotropy generation,"Fully kinetic analytic calculations of an initially Maxwellian distribution
+with arbitrary density and temperature gradients exhibit the development of
+temperature anisotropies and magnetic field growth associated with the Biermann
+battery. The calculation, performed by taking a small order expansion of the
+ratio of the Debye length to the gradient scale, predicts anisotropies and
+magnetic fields as a function of space given an arbitrary temperature and
+density profile. These predictions are shown to qualitatively match the values
+measured from particle-in-cell simulations, where the development of the Weibel
+instability occurs at the same location and with a wavenumber aligned with the
+predicted temperature anisotropy.",1707.06390v1
+2017-08-08,Reinvestigation on large perpendicular magnetic anisotropy in Fe/MgO interface from first-principles approach,"We investigated electronic structure and magnetic anisotropy in the Fe/MgO
+interface of magnetic metal and dielectric insulator under the Cr layer of
+small electronegativity, by means of the first-principles density functional
+approach. The result indicates that the interface resonance state gets occupied
+unlike a typical rigid band picture as the number of Fe layers decreases,
+finding large perpendicular anisotropies in the oscillating behavior for
+thickness dependence. We discuss scenarios of the two dimensional van Hove
+singularity associated with flat band dispersions, and also the accuracies of
+anisotropy energy in comparison with the available experimental data.",1708.02400v1
+2018-02-23,3D superconducting gap in FeSe from ARPES,"We present a systematic angle-resolved photoemission spectroscopy study of
+the superconducting gap in FeSe. The gap function is determined in a full
+Brillouin zone including all Fermi surfaces and kz-dependence. We find
+significant anisotropy of the superconducting gap in all momentum directions.
+While the in-plane anisotropy can be explained by both, nematicity-induced
+pairing anisotropy and orbital-selective pairing, the kz-anisotropy requires
+additional refinement of theoretical approaches.",1802.08668v1
+2018-09-23,Ferromagnetic resonance in thin ferromagnetic film with surface anisotropy,"The ferromagnetic resonance frequencies are obtained for a thin ferromagnetic
+film with surface anisotropy for the cases when the external magnetic field is
+applied perpendicularly or parallel to the film surface, and for various
+combinations of boundary conditions on the film surface. It is shown that in
+the presence of surface anisotropy the ferromagnetic resonance frequency
+essentially depends both on the film thickness and on the value of the surface
+anisotropy constant. The results obtained provide a basis for the correct
+interpretation of experimental data obtained by means of broadband
+ferromagnetic resonance in thin film structures.",1809.08644v1
+2019-02-11,Measuring hole g-factor anisotropies using transverse magnetic focusing,"Recent theoretical and experimental results from quasi-one dimensional heavy
+hole systems have suggested that heavy hole gases have a strongly anisotropic g
+factor. In this theoretical paper, we propose a method for measuring this
+anisotropy using transverse magnetic focusing (TMF). We demonstrate that for
+experimentally accessible fields, the g factor anisotropy leads to a relative
+variation in the characteristic of spin-splitting of the TMF spectrum which
+allows for the measurement of the anisotropy of the g factor. We show that this
+variation is insensitive to additional spin-orbit interactions, and is
+resolvable with current devices.",1902.03709v1
+2019-12-10,Study on Sub monolayer Epitaxy Growth under Anisotropic Detachment,"We have performed Kinetic Monte Carlo simulation to study the effect of
+diffusion anisotropy and bonding anisotropy on island formation at different
+temperatures during the sub-monolayer film growth in Molecular Beam Epitaxy. We
+use simple cubic solid on solid model and event based Bortz, Kalos and
+Labowitch (BKL) algorithm on Kinetic Monte Carlo method to simulate the
+physical phenomena. We have found that surface anisotropy has no significant
+role on island elongation however it influences on the island morphology,
+growth exponent and island size distribution. Elongated islands were obtained
+when bonding anisotropy was included.",1912.04877v1
+2020-06-08,The effect of anisotropy on phase transitions in graphene,"We study the effect of anisotropy (strain) on dynamical gap generation in
+graphene. We work with a low energy effective theory obtained from a
+tight-binding Hamiltonian expanded around the Dirac points in momentum space.
+We use a non-perturbative Schwinger-Dyson approach and calculate a coupled set
+of five momentum dependent dressing functions. Our results show that the
+critical coupling depends only weakly on the anisotropy parameter, and
+increases with greater anisotropy.",2006.04790v2
+2020-06-19,Anisotropy of Electric Field Fluctuations Spectrum of Solar Wind Turbulence,"To investigate the power and spectral index anisotropy in the inertial range
+of solar wind turbulence, we use 70 intervals of electric field data
+accumulated by Cluster spacecraft in the free solar wind. We compute the
+electric field fluctuation power spectra using wavelet analysis technique and
+study its spectral index variation with the change in angle between the
+heliocentric radial direction and the local mean magnetic field. We find clear
+power and spectral index anisotropy in the frequency ranging from 0.01 Hz to
+0.1 Hz, with more power in parallel fluctuations than perpendicular. We also
+report our study of anisotropy as a function of solar activity.",2006.10954v2
+2022-01-28,Theory of spin-excitation anisotropy in the nematic phase of FeSe obtained from RIXS measurements,"Recent resonant inelastic x-ray scattering (RIXS) experiments have detected a
+significant high-energy spin-excitation anisotropy in the nematic phase of the
+enigmatic iron-based superconductor FeSe, whose origin remains controversial.
+We apply an itinerant model previously used to describe the spin-excitation
+anisotropy as measured by neutron scattering measurements, with magnetic
+fluctuations included within the RPA approximation. The calculated RIXS cross
+section exhibits overall agreement with the RIXS data, including the high
+energy spin-excitation anisotropy.",2201.12008v2
+2022-05-03,"Tuning the perpendicular anisotropy of ferromagnetic films by thickness, width, and profile","Perpendicular magnetic anisotropy was found to be highly sensitive to the
+nominal thickness and morphology of laterally heterogeneous CoPd films in the
+vicinity of the metal insulator transition. We used the effect to tune the
+anisotropy by the width of lithographically patterned stripes with non-uniform
+cross-sectional thickness profiles. The phenomenon and the method can be
+suitable to control the local anisotropy of spintronic logic circuitry elements
+by their shape and lateral dimensions.",2205.01408v1
+2022-09-20,Field-Induced Spin Nematic Liquid of the $S=1/2$ Bond-Alternating Chain with the Anisotropy,"The $S=1/2$ ferromagnetic-antiferromagnetic bond-alternating spin chain with
+the anisotropy on the ferromagnetic exchange interaction in magnetic field is
+investigated using the numerical diagonalization and the density matrix
+renormalization group analyses. It is found that the nematic-spin-dominant
+Tomonaga-Luttinger liquid phase is induced by the external magnetic field for
+sufficiently large anisotropy. The phase diagram with respect to the anisotropy
+and the magnetization is presented.",2209.09740v1
+2009-06-26,Kinematic deprojection and mass inversion of spherical systems of known velocity anisotropy,"Traditionally, the mass / velocity anisotropy degeneracy (MAD) inherent in
+the spherical, stationary, non-streaming Jeans equation has been handled by
+assuming a mass profile and fitting models to the observed kinematical data.
+Here, the opposite approach is considered: the equation of anisotropic
+kinematic projection is inverted for known arbitrary anisotropy to yield the
+space radial velocity dispersion profile in terms of an integral involving the
+radial profiles of anisotropy and isotropic dynamical pressure. Then, through
+the Jeans equation, the mass profile is derived in terms of double integrals of
+observable quantities. Single integral formulas for both deprojection and mass
+inversion are provided for several simple anisotropy models (isotropic, radial,
+circular, general constant, Osipkov-Merritt, Mamon-Lokas and
+Diemand-Moore-Stadel). Tests of the mass inversion on NFW models with these
+anisotropy models yield accurate results in the case of perfect observational
+data, and typically better than 70% (in 4 cases out of 5) accurate mass
+profiles for the sampling errors expected from current observational data on
+clusters of galaxies. For the NFW model with mildly increasing radial
+anisotropy, the mass is found to be insensitive to the adopted anisotropy
+profile at 7 scale radii and to the adopted anisotropy radius at 3 scale radii.
+This anisotropic mass inversion method is a useful complementary tool to
+analyze the mass and anisotropy profiles of spherical systems. It provides the
+practical means to lift the MAD in quasi-spherical systems such as globular
+clusters, round dwarf spheroidal and elliptical galaxies, as well as groups and
+clusters of galaxies, when the anisotropy of the tracer is expected to be
+linearly related to the slope of its density.",0906.4971v3
+2011-05-23,Diffusive propagation of cosmic rays from supernova remnants in the Galaxy. II: anisotropy,"We investigate the effects of stochasticity in the spatial and temporal
+distribution of supernova remnants on the anisotropy of cosmic rays observed at
+Earth. The calculations are carried out for different choices of the diffusion
+coefficient D(E) for propagation in the Galaxy. The propagation and spallation
+of nuclei are taken into account. At high energies we assume that
+$D(E)\sim(E/Z)^{\delta}$, with $\delta=1/3$ and $\delta=0.6$ being the
+reference scenarios. The large scale distribution of supernova remnants in the
+Galaxy is modeled following the distribution of pulsars with and without
+accounting for the spiral structure of the Galaxy. Our calculations allow us to
+determine the contribution to anisotropy resulting from both the large scale
+distribution of SNRs in the Galaxy and the random distribution of the nearest
+remnants. The naive expectation that the anisotropy amplitude scales as D(E) is
+shown to be an oversimplification which does not reflect in the predicted
+anisotropy for any realistic distribution of the sources. The fluctuations in
+the anisotropy pattern are dominated by nearby sources, so that predicting or
+explaining the observed anisotropy amplitude and phase becomes close to
+impossible. We find however that the very weak energy dependence of the
+anisotropy amplitude below $10^{5}$ GeV and the rise at higher energies, can
+best be explained if the diffusion coefficient is $D(E)\sim E^{1/3}$. Faster
+diffusion, for instance with $\delta=0.6$, leads in general to an exceedingly
+large anisotropy amplitude. The spiral structure introduces interesting trends
+in the energy dependence of the anisotropy pattern, which qualitatively reflect
+the trend seen in the data. For large values of the halo size we find that the
+anisotropy becomes dominated by the large scale regular structure of the source
+distribution, leading indeed to a monotonic increase of $\delta_A$ with energy.",1105.4529v2
+2012-07-18,Spin transport in the Neel and collinear antiferromagnetic phase of the two dimensional spatial and spin anisotropic Heisenberg model on a square lattice,"We analyze and compare the effect of spatial and spin anisotropy on spin
+conductivity in a two dimensional S=1/2 Heisenberg quantum magnet on a square
+lattice. We explore the model in both the Neel antiferromagnetic (AF) phase and
+the collinear antiferromagnetic (CAF) phase. We find that in contrast to the
+effects of spin anisotropy in the Heisenberg model, spatial anisotropy in the
+AF phase does not suppress the zero temperature regular part of the spin
+conductivity in the zero frequency limit - rather it enhances it. We also
+explore the finite temperature effects on the Drude weight in the AF phase for
+various spatial and spin anisotropy parameters. We find that the Drude weight
+goes to zero as the temperature approaches zero. At finite temperatures (within
+the collision less approximation) enhancing spatial anisotropy increases the
+Drude weight value and increasing spin anisotropy decreases the Drude weight
+value. In the CAF phase (within the non-interacting approximation) the zero
+frequency spin conductivity has a finite value for non-zero values of the
+spatial anisotropy parameter. In the CAF phase increasing the spatial
+anisotropy parameter suppresses the regular part of the spin conductivity
+response at zero frequency. Furthermore, we find that the CAF phase displays a
+spike in the spin conductivity not seen in the AF phase. Inclusion of the
+smallest amount of spin anisotropy causes a gap to develop in the spin
+conductivity response of both the AF and CAF phase. Based on these studies we
+conclude that materials with spatial anisotropy are better spin conductors than
+those with spin anisotropy both at zero and finite temperatures. We utilize
+exchange parameter ratios for real material systems as inputs to the
+computation of spin conductivity.",1207.4389v1
+2019-01-12,"Revisit to electrical and thermal conductivities, Lorenz number and Knudsen number in thermal QCD in a strong magnetic field","We have explored how the electrical ($\sigma_{\rm el}$) and thermal
+($\kappa$) conductivities in a thermal QCD medium get affected in weak-momentum
+anisotropies arising either due to a strong magnetic field or due to asymptotic
+expansion. This study facilitates to understand the longevity of strong
+magnetic field through $\sigma_{el}$, Lorenz number in Wiedemann-Franz law, and
+the validity of equilibrium by the Knudsen number. We calculate the
+conductivities by solving relativistic Boltzmann transport equation in
+relaxation-time approximation within quasiparticle model at finite T and strong
+B. We have found that $\sigma_{el}$ and $\kappa$ get enhanced in a magnetic
+field-driven anisotropy, but $\sigma_{el}$ decreases with temperature, opposite
+to its faster increase in expansion-driven anisotropy. Whereas $\kappa$
+increases slowly with temperature, contrary to its rapid increase in
+expansion-driven anisotropy. The above findings are broadly attributed to three
+factors: the stretching and squeezing of distribution function in anisotropies
+generated by the magnetic field and asymptotic expansion, respectively, the
+dispersion relation and resulting phase-space factor, the relaxation-time in
+absence and presence of strong magnetic field. So $\sigma_{\rm el}$ extracts
+the time-dependence of magnetic field, which decays slower than in vacuum but
+expansion-driven anisotropy makes the decay faster. The variation in $\kappa$
+transpires that Knudsen number decreases with T but expansion-driven anisotropy
+reduces its value and magnetic field-driven anisotropy raises its value but to
+less than one, thus the system can still be in equilibrium. The ratio,
+$\kappa/\sigma_{el}$ in magnetic field-driven anisotropy increases linearly
+with temperature but with a value smaller than in expansion-driven anisotropy.
+Thus the Lorenz number can make the distinction between different anisotropies.",1901.03855v2
+2020-01-31,Momentum and its affiliated transport coefficients for a hot QCD matter in a strong magnetic field,"We have studied the effects of anisotropies on the momentum transport in a
+QCD matter by shear ($\eta$) and bulk ($\zeta$) viscosities. The anisotropies
+arise either by the strong magnetic field or by the preferential expansion.
+This study helps to understand the fluidity and location of transition point of
+matter through $\eta/s$ and $\zeta/s$ ($s$ is entropy density), respectively,
+the sound attenuation through the Prandtl number (Pl), the nature of flow by
+the Reynolds number (Rl), and the competition between momentum and charge
+diffusions. The viscosities are calculated in the relaxation time approximation
+of kinetic theory within the quasiparticle model. Compared to isotropic medium,
+both $\eta$ and $\zeta$ get increased in magnetic field-driven (B-driven)
+anisotropy, contrary to the decrease in expansion-driven anisotropy. $\eta$
+increases with temperature faster in former case than in latter case whereas
+$\zeta$ in former case decreases with temperature and in latter case, it is
+meagre and diminishes at a specific temperature. So the viscosities can
+distinguish aforesaid anisotropies. Thus, $\eta/s$ gets enhanced in former case
+and in latter case, it becomes smaller than isotropic one. Similarly $\zeta/s$
+gets amplified but decreases faster with the temperature in a strong magnetic
+field. The Prandtl number gets increased in B-induced anisotropy and gets
+decreased in expansion-induced anisotropy, compared to isotropic one. Since, Pl
+is found larger than 1, the sound attenuation is governed by momentum
+diffusion. The B-driven anisotropy makes the Reynolds number smaller than one,
+whereas the expansion-driven anisotropy makes it larger. The ratio
+($\frac{\eta}{s}/\frac{\sigma_{\rm el}}{T}$) gets amplified in B-driven
+anisotropy whereas it gets reduced in expansion-driven anisotropy. Since, the
+ratio is always more than one, the momentum diffusion prevails over the charge
+diffusion.",2001.11788v2
+1995-02-02,CMB ANISOTROPIES: AN OVERVIEW,"A brief outline of the current status of CMB anisotropies and what they might
+mean, heavily biased towards the perspective of Berkeley theorists. Based on a
+talk presented at the 17th Texas Symposium on Relativistic Astrophysics held in
+Munich, December 1994.",9502011v1
+1999-03-30,Are you sure that the anisotropies in the microwave background radiation are really cosmological rather than purely Galactic in origin?,"New calculations of the Galactic contamination over microwave background
+radiation anisotropies are carried out. On one hand, when a frequency-dependent
+contrast of molecular clouds with respect to the Galactic background of the
+diffuse interstellar medium is taken into account, the anisotropic amplitude
+produced by Galactic dust is increased with respect to previous calculations
+and this is of the same order as that of the data from the observations. On the
+other hand, if we take into account rotational dust emission, for instance, a
+frequency independence of anisotropies in the microwave range may be obtained.
+  This leads to the possibility that under some particular, but not impossible,
+conditions all the microwave background radiation anisotropies may be due to
+Galactic foregrounds rather than cosmological in origin. Moreover, a suspected
+coincidence between the typical angular sizes of the microwave background
+radiation anisotropies and those of nearby molecular clouds makes more
+plausible the hypothesis of a purely Galactic origin for these anisotropies. It
+is also argued that the correlation among structures at different frequencies,
+the comparison of the power spectrum at different frequencies and the galactic
+latitude dependence of the anisotropies are not yet proofs in favour of either
+a cosmological or Galactic origin.",9903460v2
+1999-04-25,The Limits on Cosmological Anisotropies and Inhomogeneities from COBE Data,"Assuming that the cosmological principle holds, Maartens, Ellis and Stoeger
+(MES) recently constructed a detailed scheme linking anisotropies in the cosmic
+background radiation (CMB) with anisotropies and inhomogeneities in the large
+scale structure of the universe and showed how to place limits on those
+anisotropies and inhomogeneities simply by using CMB quadrupole and octupole
+limits. First we indicate and discuss the connection between the covariant
+multipole moments of the temperature anisotropy used in the MES scheme and the
+quadrupole and octupole results from COBE. Then we introduce those results into
+the MES limit equations to obtain definite quantitative limits on the complete
+set of cosmological measures of anisotropy and inhomogeneity.
+  We find that all the anisotropy measures are less than 10^{-4} in the case of
+those not affected by the expansion rate H, and less than 10^{-6} Mpc^{-1} in
+the case of those which are. These results quantitatively demonstrate that the
+observable universe is indeed close to Friedmann-Lemaitre-Robertson-Walker
+(FLRW) on the largest scales, and can be adequately modelled by an almost-FLRW
+model -- that is, the anisotropies and inhomogeneities characterizing the
+observable universe on the largest scales are not too large to be considered
+perturbations to FLRW.",9904346v1
+1998-12-21,Cosmological Birefringence and the Microwave Background,"We show that significant anisotropy in electromagnetic propagation generates
+a distinctive signature in the microwave background. The anisotropy may be
+determined by looking at the cross correlator of the $E$-mode and $B$-mode
+polarisation spectrum.",9812077v1
+2005-10-03,Tuning anisotropies for dynamical gauge configurations,"We present methods and results for the tuning of quark and gluon anisotropies
+for improved actions in N_f = 2 QCD.",0510016v1
+2011-01-14,Observational Scan Induced Artificial CMB Anisotropy,"To reliably detect the cosmic microwave background (CMB) anisotropy is of
+great importance in understanding the birth and evolution of the Universe. One
+of the difficulties in CMB experiments is the domination of measured CMB
+anisotropy maps by the Doppler dipole moment from the motion of the antenna
+relative to the CMB. For each measured temperature the expected dipole
+component has to be calculated separately and then subtracted from the data. A
+small error in dipole direction, antenna pointing direction, sidelobe pickup
+contamination, and/or timing synchronism, can raise significant deviation in
+the dipole cleaned CMB temperature. After a full-sky observational scan, the
+accumulated deviations will be structured with a pattern closely correlated to
+the observation pattern with artificial anisotropies on large scales, including
+artificial quadrupole, octopole etc in the final CMB map. Such scan-induced
+anisotropies on large scales can be predicted by the true dipole moment and
+observational scan scheme. Indeed, the expected scan-induced quadrupole pattern
+of the WMAP mission is perfectly in agreement with the published WMAP
+quadrupole. With the scan strategy of the Planck mission, we predict that
+scan-induced anisotropies will also produce an artificially aligned quadrupole.
+The scan-induced anisotropy is a common problem for all sweep missions and,
+like the foreground emissions, has to be removed from observed maps. Without
+doing so, CMB maps from COBE, WMAP, and Planck as well, are not reliable for
+studying the CMB anisotropy.",1101.2720v2
+2013-08-26,Constraints on the source of ultra-high energy cosmic rays using anisotropy vs chemical composition,"The joint analysis of anisotropy signals and chemical composition of
+ultra-high energy cosmic rays offers strong potential for shedding light on the
+sources of these particles. Following up on an earlier idea, this paper studies
+the anisotropies produced by protons of energy >E/Z, assuming that anisotropies
+at energy >E have been produced by nuclei of charge Z, which share the same
+magnetic rigidity. We calculate the number of secondary protons produced
+through photodisintegration of the primary heavy nuclei. Making the extreme
+assumption that the source does not inject any proton, we find that the
+source(s) responsible for anisotropies such as reported by the Pierre Auger
+Observatory should lie closer than ~20-30, 80-100 and 180-200 Mpc if the
+anisotropy signal is mainly composed of oxygen, silicon and iron nuclei
+respectively. A violation of this constraint would otherwise result in the
+secondary protons forming a more significant anisotropy signal at lower
+energies. Even if the source were located closer than this distance, it would
+require an extraordinary metallicity >120, 1600, 1100 times solar metallicity
+in the acceleration zone of the source, for oxygen, silicon and iron
+respectively, to ensure that the concomitantly injected protons not to produce
+a more significant low energy anisotropy. This offers interesting prospects for
+constraining the nature and the source of ultra-high energy cosmic rays with
+the increase in statistics expected from next generation detectors.",1308.5699v2
+2015-01-28,In-plane anisotropy effect on critical transition field in nanogranular films with perpendicular anisotropy,"The influence of the in-plane anisotropy on the magnetization of a
+nanogranular film with perpendicular anisotropy has been studied. It is shown
+that if a magnetic field is tilted with respect to the film normal, a critical
+transition from the inhomogeneous magnetic state of granules with noncollinear
+directions of their moments to the homogeneous one with parallel orientation of
+granular magnetic moments takes place. The in-plane anisotropy is found to
+affect the angular dependence of the critical field. The ensemble of oriented
+biaxial particles is theoretically described in the double-well potential
+approximation. Despite the biaxial magnetic anisotropy of particles, their
+ensemble, if in the inhomogeneous state, is divided into two subensembles, with
+the magnetic moments of particles being collinear in each of them. In the
+critical field, a transition from the inhomogeneous state with two subensembles
+into the homogeneous one takes place. The results of theoretical calculations
+are compared with experimental data for a nanogranular Co/Al2On film with
+perpendicular anisotropy containing 74.5 at.% Co, which exceeds the percolation
+threshold. The magnetic moment of this film is a sum of two contributions: from
+nanogranules with biaxial anisotropy and a phase forming the percolation
+cluster. The magnetic properties of nanogranules, whose contribution is
+separated from the total film magnetization, agree well with the calculation
+data.",1501.07252v1
+2016-06-23,Molecules associated to Hardy spaces with pointwise variable anisotropy,"In this paper we introduce molecules associated to Hardy spaces with
+pointwise variable anisotropy, and prove that each molecule can be represented
+as a sum of atoms.",1606.07245v1
+2016-08-14,Axisymmetric equilibria with pressure anisotropy and plasma flow,"In this Master thesis we investigate the influence of pressure anisotropy and
+incompressible flow of arbitrary direction on the equilibrium properties of
+magnetically confined, axisymmetric toroidal plasmas. The main novel
+contribution is the derivation of a pertinent generalised Grad-Shafranov
+equation. This equation includes six free surface functions and recovers known
+Grad-Shafranov-like equations in the literature as well as the usual static,
+isotropic one. The form of the generalised equation indicates that pressure
+anisotropy and flow act additively on equilibrium. In addition, two sets of
+analytical solutions, an extended Solovev one with a plasma reaching the
+separatrix and an extended Hernegger-Maschke one for a plasma surrounded by a
+fixed boundary possessing an X-point, are constructed, particularly in
+relevance to the ITER and NSTX tokamaks. Furthermore, the impacts both of
+pressure anisotropy, through an anisotropy function assumed to be uniform on
+the magnetic surfaces, and plasma flow, via the variation of an Alfvenic Mach
+function, on these equilibria are examined.
+  It turns out that depending on the maximum value and the shape of an
+anisotropy function, the anisotropy can act either paramagnetically or
+diamagnetically. Also, in most of the cases considered both the anisotropy and
+the flow have stronger effects on NSTX equilibria than on ITER ones. We
+conjecture that these effects may have an influence on plasma stability and
+transport, and play a role in the transitions to the improved confinement
+regimes in tokamaks.",1608.04083v1
+2017-06-29,Characterization of the velocity anisotropy of accreted globular clusters,"Galactic globular clusters (GCs) are believed to have formed in-situ in the
+Galaxy as well as in dwarf galaxies later accreted onto the Milky Way. However,
+to date, there is no unambiguous signature to distinguish accreted GCs. Using
+specifically designed $N$-body simulations of GCs evolving in a variety of
+time-dependent tidal fields (describing the potential of a dwarf galaxy-Milky
+Way merger), we analyze the effects imprinted to the internal kinematics of an
+accreted GC. In particular, we look at the evolution of the velocity
+anisotropy. Our simulations show that at early phases, the velocity anisotropy
+is determined by the tidal field of the dwarf galaxy and subsequently the
+clusters will adapt to the new tidal environment, losing any signature of their
+original environment in a few relaxation times. At 10 Gyr, GCs exhibit a
+variety of velocity anisotropy profiles, namely, isotropic velocity
+distribution in the inner regions and either isotropy or radial/tangential
+anisotropy in the intermediate and outer regions. Independently of an accreted
+origin, the velocity anisotropy primarily depends on the strength of the tidal
+field cumulatively experienced by a cluster. Tangentially anisotropic clusters
+correspond to systems that have experienced stronger tidal fields and are
+characterized by higher tidal filling factor, $r_{50}/r_j\gtrsim0.17$, higher
+mass loss $\gtrsim60\%$ and relaxation times $t_{rel}\lesssim10^9$ Gyr.
+Interestingly, we demonstrate that the presence of tidal tails can
+significantly contaminate the measurements of velocity anisotropy when a
+cluster is observed in projection. Our characterization of the velocity
+anisotropy profiles in different tidal environments provides a theoretical
+benchmark for the interpretation of the unprecedented amount of
+three-dimensional kinematic data progressively available for Galactic GCs.",1706.09815v1
+2018-04-05,Phase-field modeling of equilibrium precipitate shapes under the influence of coherency stresses,"Coherency misfit stresses and their related anisotropies are known to
+influence the equilibrium shapes of precipitates. Additionally, mechanical
+properties of the alloys are also dependent on the shapes of the precipitates.
+Therefore, in order to investigate the mechanical response of a material which
+undergoes precipitation during heat treatment, it is important to derive the
+range of precipitate shapes that evolve. In this regard, several studies have
+been conducted in the past using sharp interface approaches where the influence
+of elastic energy anisotropy on the precipitate shapes has been investigated.
+In this paper, we propose a diffuse interface approach which allows us to
+minimize grid-anisotropy related issues applicable in sharp-interface methods.
+In this context, we introduce a novel phase-field method where we minimize the
+functional consisting of the elastic and surface energy contributions while
+preserving the precipitate volume. Using this method we reproduce the
+shape-bifurcation diagrams for the cases of pure dilatational misfit that have
+been studied previously using sharp interface methods and then extend them to
+include interfacial energy anisotropy with different anisotropy strengths which
+has not been a part of previous sharp-interface models. While we restrict
+ourselves to cubic anisotropies in both elastic and interfacial energies in
+this study, the model is generic enough to handle any combination of
+anisotropies in both the bulk and interfacial terms. Further, we have examined
+the influence of asymmetry in dilatational misfit strains along with
+interfacial energy anisotropy on precipitate morphologies.",1804.01763v1
+2018-11-28,Effect of magnetic anisotropy on Skyrmions with a high topological number in itinerant magnets,"We report our numerical results for the effect of magnetic anisotropy on a
+Skyrmion crystal with a high topological number of two, which was recently
+discovered in an itinerant electron model [R. Ozawa, S. Hayami, and Y. Motome,
+Phys. Rev. Lett. 118, 147205 (2017)]. By performing numerical simulations based
+on the kernel polynomial method and the Langevin dynamics for the Kondo lattice
+model on a triangular lattice, we find that the topological property remains
+robust against the single-ion anisotropy, while the magnetic texture is
+deformed continuously. The resultant spin structure is characterized by three
+wave numbers (triple-$Q$ state), in which the $xy$ component of spins forms a
+magnetic vortex crystal and the $z$ component of spins behaves a sinusoidal
+wave. For larger anisotropy, we show that the system exhibits a phase
+transition from the Skyrmion crystal to topologically trivial phases with
+vanishing scalar chirality: a single-$Q$ collinear and double-$Q$ noncoplanar
+states for the easy-axis and easy-plane anisotropy, respectively. We also
+examine the effect of the single-ion anisotropy in an external magnetic field,
+and find that the field range of the Skyrmion crystal is rather insensitive to
+the anisotropy, in contrast to another Skyrmion crystal with the topological
+number of one whose field range is considerably extended (reduced) by the
+easy-axis (easy-plane) anisotropy.",1811.11336v1
+2019-02-09,Antiferromagnetic phase transition in $Cr_{2}As$ via anisotropy of exchange interactions,"The electronic structure of anti-ferromagnetic $Cr_{2}As$ is investigated.
+Anisotropy of exchange interactions between chrome sub-lattices is determined
+($J^{X}(Cr_{I}-Cr_{II}) =4.77 meV,J^{Y}(Cr_{I}-Cr_{II}) =-6.36 meV$). The
+behavior of exchange integrals from magnetic structure is analyzed.",1902.03337v1
+2019-04-08,Three-dimensional local anisotropy of velocity fluctuations in the solar wind,"We analyse velocity fluctuations in the solar wind at magneto-fluid scales in
+two datasets, extracted from Wind data in the period 2005-2015, that are
+characterised by strong or weak expansion. Expansion affects measurements of
+anisotropy because it breaks axisymmetry around the mean magnetic field.
+Indeed, the small-scale three-dimensional local anisotropy of magnetic
+fluctuations ({\delta}B) as measured by structure functions (SF_B) is
+consistent with tube-like structures for strong expansion. When passing to weak
+expansion, structures become ribbon-like because of the flattening of SFB along
+one of the two perpendicular directions. The power-law index that is consistent
+with a spectral slope -5/3 for strong expansion now becomes closer to -3/2.
+This index is also characteristic of velocity fluctuations in the solar wind.
+We study velocity fluctuations ({\delta}V) to understand if the anisotropy of
+their structure functions (SF_V ) also changes with the strength of expansion
+and if the difference with the magnetic spectral index is washed out once
+anisotropy is accounted for. We find that SF_V is generally flatter than SF_B.
+When expansion passes from strong to weak, a further flattening of the
+perpendicular SF_V occurs and the small-scale anisotropy switches from
+tube-like to ribbon-like structures. These two types of anisotropy, common to
+SF_V and SF_B, are associated to distinct large-scale variance anisotropies of
+{\delta}B in the strong- and weak-expansion datasets. We conclude that SF_V
+shows anisotropic three-dimensional scaling similar to SF_B, with however
+systematic flatter scalings, reflecting the difference between global spectral
+slopes.",1904.04118v1
+2019-11-29,"Filaments and striations: anisotropies in observed, supersonic, highly-magnetised turbulent clouds","Stars form in highly-magnetised, supersonic turbulent molecular clouds. Many
+of the tools and models that we use to carry out star formation studies rely
+upon the assumption of cloud isotropy. However, structures like high-density
+filaments in the presence of magnetic fields, and magnetosonic striations
+introduce anisotropies into the cloud. In this study we use the two-dimensional
+(2D) power spectrum to perform a systematic analysis of the anisotropies in the
+column density for a range of Alfv\'en Mach numbers ($\mathcal{M}_A=0.1$--$10$)
+and turbulent Mach numbers ($\mathcal{M}=2$--$20$), with 20 high-resolution,
+three-dimensional (3D) turbulent magnetohydrodynamic simulations. We find that
+for cases with a strong magnetic guide field, corresponding to
+$\mathcal{M}_A<1$, and $\mathcal{M}\lesssim 4$, the anisotropy in the column
+density is dominated by thin striations aligned with the magnetic field, while
+for $\mathcal{M}\gtrsim 4$ the anisotropy is significantly changed by
+high-density filaments that form perpendicular to the magnetic guide field.
+Indeed, the strength of the magnetic field controls the degree of anisotropy
+and whether or not any anisotropy is present, but it is the turbulent motions
+controlled by $\mathcal{M}$ that determine which kind of anisotropy dominates
+the morphology of a cloud.",1911.13090v1
+2020-11-11,Vital role of anisotropy in cubic chiral skyrmion hosts,"The impact of magnetic anisotropy on the skyrmion lattice (SkL) state in
+cubic chiral magnets has been overlooked for long, partly because a
+semi-quantitative description of the thermodynamically stable SkL phase pocket
+forming near the Curie temperature could be achieved without invoking
+anisotropy effects. However, there has been a range of phenomena reported
+recently in these materials, such as the formation of low-temperature tilted
+conical and SkL states as well as temperature-induced transformations of
+lattice geometry in metastable SkL states, where anisotropy was suspected to
+play a key role. To settle this issue on experimental basis, we quantified the
+cubic anisotropy in a series of CoZnMn-type cubic chiral magnets. We found that
+the strength of anisotropy is highly enhanced towards low temperatures in all
+the compounds, moreover, not only the magnitude but also the character of cubic
+anisotropy drastically varies upon changing the Co/Mn ratio. We correlate these
+changes with temperature- and composition-induced variations of the helical
+modulation vectors, the anharmonicity and structural rearrangements of the
+metastable SkLs and the spin relaxation rates. Similar systematic studies on
+magnetic anisotropy may not only pave the way for a quantitative and unified
+description of the stable and metastable modulated spin textures in cubic
+chiral magnets but would also help exploring further topological spin textures
+in this large class of skyrmion hosts.",2011.05967v1
+2021-02-10,"Screening, Friedel oscillations, RKKY interaction, and Drude transport in anisotropic two-dimensional systems","We investigate the effect of the mass anisotropy on Friedel Oscillations,
+Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, screening properties, and
+Boltzmann transport in two dimensional (2D) metallic and doped semiconductor
+systems. We calculate the static polarizability and the dielectric function
+within the random phase approximation with the mass anisotropy fully taken into
+account without making any effective isotropic approximation in the theory. We
+find that carrier screening exhibits an isotropic behavior for small momenta
+despite the anisotropy of the system, and becomes strongly anisotropic above a
+certain threshold momentum. Such an anisotropy of screening leads to
+anisotropic Friedel oscillations, and an anisotropic RKKY interaction
+characterized by a periodicity dependent on the direction between the localized
+magnetic moments. We also explore the disorder limited dc transport properties
+in the presence of mass anisotropy based on the Boltzmann transport theory.
+Interestingly, we find that the anisotropy ratio of the short range disorder
+limited resistivity along the heavy- and light-mass directions is always the
+same as the mass anisotropy ratio whereas for the long range disorder limited
+resistivity the anisotropy ratio is the same as the mass ratio only in the low
+density limit, and saturates to the square root of the mass ratio in the high
+density limit. Our theoretical work should apply to many existing and
+to-be-discovered anisotropic 2D systems.",2102.05659v2
+2021-02-26,Evidence of a thick halo for the spatial-dependent propagation model with Cosmic Ray anisotropy,"The spatial-dependent propagation (SDP) model with a nearby source works well
+to reproduce the co-evolving features of both cosmic ray (CR) nuclei spectra
+and anisotropy. However, it is well known that the Sun is offset from the
+Galactic plane. This will lead to a dominating anisotropy in perpendicular
+direction, which is discrepant with observations. Thus it is necessary to
+reboot further investigation into the effect of the solar offset. In this work,
+for the first time the combined studies of the solar offset, nuclei spectra and
+anisotropy are performed based on the SDP model. As a result, to reproduce CR
+spectra and anisotropy, the thickness of the halo $\rm (\xi z_h)$ increases
+linearly with the displacement of the Sun. When the offset is $\rm \sim8~pc$ as
+estimated from the matter-borne methods, $\rm \xi z_h$ is about 0.9 kpc, which
+is a much thicker halo than usually. Moreover, the PeV anisotropy could
+estimate the value of diffusion coefficient, thus breaking the degeneracy of
+diffusion coefficient and halo thickness. Therefore it is a good messenger to
+constrain the halo thickness. On the other hand, the anisotropy in PeV energy
+region, as a new probe, might also shed new light to constrain the solar
+offset. We hope that the anisotropy at the energies of $\rm \sim TeV$ to $\rm
+PeV$ can be finely measured by LHAASO experiment, leading to a better
+understanding about the thick halo.",2102.13498v2
+2021-08-11,Instabilities of spin-1 Kitaev spin liquid phase in presence of single-ion anisotropies,"We study the spin-one Kitaev model on the honeycomb lattice in the presence
+of single-ion anisotropies. We consider two types of single ion anisotropies: A
+$D_{111}$ anisotropy which preserves the symmetry between $X$, $Y$, and $Z$
+bonds but violates flux conservation and a $D_{100}$ anisotropy that breaks the
+symmetry between $X$, $Y$, and $Z$ bonds but preserves flux conservation. We
+use series expansion methods, degenerate perturbation theory, and exact
+diagonalization to study these systems. Large positive $D_{111}$ anisotropy
+leads to a simple product ground state with conventional magnon-like
+excitations, while large negative $D_{111}$ leads to a broken symmetry and
+degenerate ground states. For both signs there is a phase transition at a small
+$|D_{111}| \approx 0.12$ separating the more conventional phases from the
+Kitaev spin liquid phase. With large $D_{100}$ anisotropy, the ground state is
+a simple product state, but the model lacks conventional dispersive excitations
+due to the large number of conservation laws. Large negative $D_{100}$ leads to
+decoupled one-dimensional systems and many degenerate ground states. No
+evidence of a phase transition is seen in our numerical studies at any finite
+$D_{100}$. Convergence of the series expansion extrapolations all the way to
+$D_{100}=0$ suggests that the nontrivial Kitaev spin liquid is a singular limit
+of this type of single-ion anisotropy going to zero, which also restores
+symmetry between the $X$, $Y$, and $Z$ bonds.",2108.05040v2
+2022-03-16,Theoretical analysis of single-ion anisotropy in $d^3$ Mott insulators,"An effective spin model for Mott insulators is determined by the symmetries
+involved among magnetic sites, electron fillings, and their interactions. Such
+a spin Hamiltonian offers insight to mechanisms of magnetic orders and magnetic
+anisotropy beyond the Heisenberg model. For a spin moment S bigger than 1/2,
+single-ion anisotropy is in principle allowed. However, for $d^3$ Mott
+insulators with large cubic crystal field splitting, the single-ion anisotropy
+is absent within the LS coupling, despite S = 3/2 local moment. On the other
+hand, preferred magnetic moment directions in $d^3$ materials have been
+reported, which calls for a further theoretical investigation. Here we derive
+the single-ion anisotropy interaction using the strong-coupling perturbation
+theory. The cubic crystal field splitting including $e_g$ orbitals, trigonal
+distortions, Hund's coupling, and spin-orbit coupling beyond the LS scheme are
+taken into account. For compressed distortion, the spin-orbit coupling at
+magnetic sites can favor either the easy-axis or the easy-plane while that of
+anions leads to easy-axis anisotropy. We apply the theory on $\rm{CrX}_3$ with
+X = Cl and I, and show the dependence of the single-ion anisotropy on the
+strength of the spin-orbit couplings of both magnetic and anion sites.
+Significance of the single-ion anisotropy in ideal two-dimensional magnets is
+also discussed.",2203.08836v3
+2022-08-06,Representing the stress and strain energy of elastic solids with initial stress and transverse texture anisotropy,"Real-world solids, such as rocks, soft tissues, and engineering materials,
+are often under some form of stress. Most real materials are also, to some
+degree, anisotropic due to their microstructure, a characteristic often called
+the `texture anisotropy'. This anisotropy can stem from preferential grain
+alignment in polycrystalline materials, aligned micro-cracks, or structural
+reinforcement, such as collagen bundles in biological tissues, steel rods in
+prestressed concrete and reinforcing fibres in composites. Here we establish a
+framework for initially stressed solids with transverse texture anisotropy. We
+consider that the strain energy per unit mass of the reference is an explicit
+function of the elastic deformation gradient, the initial stress tensor, and
+the texture anisotropy. We determine the corresponding constitutive relations
+and develop examples of nonlinear strain energies which depend explicitly on
+the initial stress and direction of texture anisotropy. As an application, we
+then employ these models to analyse the stress distribution of an inflated
+initially stressed cylinder with texture anisotropy, and the tension of a
+welded metal plate. We also deduce the elastic moduli needed to describe linear
+elasticity from stress reference with transverse texture anisotropy. As an
+example we show how to measure the stress with small-amplitude shear waves.",2208.03502v1
+2022-11-02,Electronic anisotropy in magic-angle twisted trilayer graphene,"Due to its potential connection with nematicity, electronic anisotropy has
+been the subject of intense research effort on a wide variety of material
+platforms. The emergence of spatial anisotropy not only offers a
+characterization of material properties of metallic phases, which cannot be
+accessed via conventional transport techniques, but it also provides a unique
+window into the interplay between Coulomb interaction and broken symmetry
+underlying the electronic order. In this work, we utilize a new scheme of
+angle-resolved transport measurement (ARTM) to characterize electron anisotropy
+in magic-angle twisted trilayer graphene. By analyzing the dependence of
+spatial anisotropy on moir\'e band filling, temperature and twist angle, we
+establish the first experimental link between electron anisotropy and the
+cascade phenomenon, where Coulomb interaction drives a number of isospin
+transitions near commensurate band fillings. Furthermore, we report the
+coexistence between electron anisotropy and a novel electronic order that
+breaks both parity and time reversal symmetry. Combined, the link between
+electron anisotropy, cascade phenomenon and PT-symmetry breaking sheds new
+light onto the nature of electronic order in magic-angle graphene moir\'e
+systems.",2211.01352v1
+2023-05-04,Is the Universe anisotropic right now? Comparing the real Universe with the Kasner's space-time,"We investigate possible astronomical manifestations of space-time anisotropy.
+The homogeneous vacuum Kasner solution was chosen as a reference anisotropic
+cosmological model because there are no effects caused by inhomogeneity in this
+simple model with a constant degree of anisotropy. This anisotropy cannot
+become weak. The study of its geodesic structure made it possible to clarify
+the properties of this space-time. It showed that the degree of manifestation
+of anisotropy varies significantly depending on the travel time of the light
+from the observed object. For nearby objects, for which it does not exceed half
+the age of the universe, the manifestations of anisotropy are very small.
+Distant objects show more pronounced manifestations, for example, in the
+distribution of objects over the sky and over photometric distances. These
+effects for each of the individual objects decrease with time, but in general,
+the manifestations of anisotropy in the Kasner space-time remain constant due
+to the fact that new sources emerging from beyond the cosmological horizon.We
+analyse observable signatures of the Kasner-type anisotropy and compare it to
+observations. These effects were not found in astronomical observations,
+including the study of the CMB. We can assume that the Universe has always been
+isotropic or almost isotropic since the recombination era. This does not
+exclude the possibility of its significant anisotropy at the moment of the Big
+Bang followed by rapid isotropization during the inflationary epoch.",2305.02726v2
+2023-05-09,Exploring the spectrum of stochastic gravitational-wave anisotropies with pulsar timing arrays,"Anisotropies in the nanohertz gravitational-wave background are a compelling
+next target for pulsar timing arrays (PTAs). Measurements or informative upper
+limits to the anisotropies are expected in the near future and can offer
+important clues about the origin of the background and the properties of the
+sources. Given that each source is expected (in the simplest scenario of
+circular inspirals) to emit at a fixed frequency, the anisotropy will most
+generally vary from one frequency to another. The main result presented in this
+work is an analytical model for the anisotropies produced by a population of
+inspiralling supermassive black-hole binaries (SMBHBs). This model can be
+immediately connected with parametrizations of the SMBHB mass function and can
+be easily expanded to account for new physical processes taking place within
+the PTA frequency band. We show that a variety of SMBHB models predict
+significant levels of anistropy at the highest frequencies accessible to PTA
+observations and that measurements of anisotropies can offer new information
+regarding this population beyond the isotropic component. We also model the
+impact of additional dynamical effects driving the binary towards merger and
+show that, if these processes are relevant within the PTA band, the
+detectability of anisotropies relative to the isotropic background will be
+enhanced. Finally, we use the formalism presented in this work to predict the
+level anisotropy of the circular and linear polarizations of the SGWB due to
+the distribution of binary orientation angles with respect to the line of
+sight.",2305.05690v1
+2023-09-27,Impact of surface anisotropy on the spin-wave dynamics in thin ferromagnetic film,"The spin-wave dynamics in the thin CoFeB film in Damon-Eshbach geometry are
+studied in three cases of boundary conditions -- free boundary conditions,
+symmetrical surface anisotropy, and one-sided surface anisotropy. The
+analytical model created by Wolfram and De Wames was extended to include
+perpendicular surface anisotropy in boundary conditions. Its comparison with
+numerical simulations demonstrate perfect agreement between the approaches. The
+analysis of the dispersion relation indicates that the presence of surface
+anisotropy increases the avoided crossing size between Damon-Eshbach mode and
+perpendicular standing modes. Additionally, asymmetrical one-sided surface
+anisotropy induces nonreciprocity in the dispersion relation. In-depth analysis
+of the avoided crossing size is conducted for systems with different boundary
+conditions, different thicknesses, surface anisotropy constant values, and
+external magnetic fields. It shows the significant role of the strength of
+surface localization of Damon-Eshbach mode and the symmetry of perpendicular
+standing modes in the avoided crossing broadening. Interestingly, for specific
+set of parameters the interaction between the particular modes can be
+suppressed, resulting in a mode crossing. Such a crossing, which occurs only on
+one side of the dispersion relation in a one-sided surface anisotropy system,
+can be utilized in nonreciprocal devices.",2309.15583v1
+2023-12-31,Anisotropy of quadratic forms over a global field of odd characteristic is diophantine,"We prove that the anisotropy of quadratic forms over any global field of
+characteristic not equal to 2 is diophantine, by using a generalization of the
+method of Koenigsmann and some known results in diophantine sets and quadratic
+forms.",2401.00537v1
+2024-03-11,On convex comparison for exterior Bernoulli problems with discontinuous anisotropy,"We give a new proof of a convex comparison principle for exterior Bernoulli
+free boundary problems with discontinuous anisotropy.",2403.07212v1
+2024-02-20,Exploring magnetic anisotropy in bcc-structured ferromagnetic thin films with three spin layers using the fourth order perturbed Heisenberg Hamiltonian,"This study investigates into the analysis of ferromagnetic thin films with a
+body centered cubic lattice and three spin layers, utilizing the solution of
+the fourth-order perturbed Heisenberg Hamiltonian equation with seven magnetic
+energy parameters. Spin-exchange interaction, magnetic dipole interaction,
+second-order magnetic anisotropy,fourth-order magnetic anisotropy, applied
+magnetic field, demagnetization energy, and stress-induced anisotropy were all
+taken into account. According to 3D plots, the minimum order of energy was
+observed when the second order magnetic anisotropy constant in the middle spin
+layer is less than those of the bottom and top spin layers. In all cases, the
+values of stress-induced anisotropy at the maxima of 3D plots are exactly the
+same when the values of the second-order magnetic anisotropy constants of the
+bottom, middle, and top spin layers are interchanged with each other. In 2D
+plots, the angle between consecutive magnetic easy and hard directions is
+approximately 90 degrees in all cases. Additionally, the magnetic easy and hard
+directions were observed to have exactly the same values when the second-order
+magnetic anisotropy constant of the spin layers changes. These results were
+compared with the results obtained using the second and third order perturbed
+Heisenberg Hamiltonian.",2403.13817v1
+2024-04-03,In-situ tunable giant electrical anisotropy in a grating gated AlGaN/GaN two-dimensional electron gas,"Materials with in-plane electrical anisotropy have great potential for
+designing artificial synaptic devices. However, natural materials with strong
+intrinsic in-plane electrical anisotropy are rare. We introduce a simple
+strategy to produce extremely large electrical anisotropy via grating gating of
+a semiconductor two-dimensional electron gas (2DEG) of AlGaN/GaN. We show that
+periodically modulated electric potential in the 2DEG induces in-plane
+electrical anisotropy, which is significantly enhanced in a magnetic field,
+leading to an ultra large electrical anisotropy. This is induced by a giant
+positive magnetoresistance and a giant negative magnetoresistance under two
+orthogonally oriented in-plane current flows, respectively. This giant
+electrical anisotropy is in-situ tunable by tailoring both the grating gate
+voltage and the magnetic field. Our semiconductor device with controllable
+giant electrical anisotropy will stimulate new device applications, such as
+multi-terminal memtransistors and bionic synapses.",2404.02427v1
+1994-06-17,A Two-Fluid Approximation for Calculating the Cosmic Microwave Background Anisotropies,"We present a simple, yet accurate approximation for calculating the cosmic
+microwave background anisotropy power spectrum in adiabatic models. It consists
+of solving for the evolution of a two-fluid model until the epoch of
+recombination and then integrating over the sources to obtain the CMB
+anisotropy power spectrum. The approximation is useful both for a physical
+understanding of CMB anisotropies, as well as for a quantitative analysis of
+cosmological models. Comparison with exact calculations shows that the accuracy
+is typically better than 20 percent over a large range of angles and
+cosmological models, including those with curvature and cosmological constant.
+Using this approximation we investigate the dependence of the CMB anisotropies
+on the cosmological parameters. We identify six dimensionless parameters that
+uniquely determine the anisotropy power spectrum within our approximation. CMB
+experiments on different angular scales could in principle provide information
+on all these parameters. In particular, mapping of the Doppler peaks would
+allow an independent determination of baryon mass density, matter mass density
+and Hubble constant.",9406050v1
+1996-09-05,Large Angular Scale CMB Anisotropy Induced by Cosmic Strings,"We simulate the anisotropy in the cosmic microwave background (CMB) induced
+by cosmic strings. By numerically evolving a network of cosmic strings we
+generate full-sky CMB temperature anisotropy maps. Based on $192$ maps, we
+compute the anisotropy power spectrum for multipole moments $\ell \le 20$. By
+comparing with the observed temperature anisotropy, we set the normalization
+for the cosmic string mass-per-unit-length $\mu$, obtaining $G\mu/c^2=1.05
+{}^{+0.35}_{-0.20} \times10^{-6}$, which is consistent with all other
+observational constraints on cosmic strings. We demonstrate that the anisotropy
+pattern is consistent with a Gaussian random field on large angular scales.",9609038v1
+1999-09-22,An intrinsic anisotropy in the angular distribution of gamma-ray bursts,"The anisotropy of the sky distribution of 2025 gamma-ray bursts (GRBs)
+collected in Current BATSE catalog is confirmed. It is shown that the
+quadrupole term being proportional to $\sim \sin 2b \sin l$ is non-zero with a
+probability 99.9%. The occurrence of this anisotropy term is then supported by
+the binomial test even with the probability 99.97%. It is also argued that this
+anisotropy cannot be caused exclusively by instrumental effects due to the
+non-uniform sky exposure of BATSE instrument; there should exist also some
+intrinsic anisotropy in the angular distribution of GRBs. Separating GRBs into
+short and long subclasses, it is shown that the 251 short ones are distributed
+anisotropically, but the 681 long ones seem to be distributed still
+isotropically. The 2-sample Kolmogorov-Smirnov test shows that they are
+distributed differently with a 98.7% probability. The character of anisotropy
+suggests that the cosmological origin of short GRBs further holds, and there is
+no evidence for their Galactical origin. The work in essence contains the key
+ideas and results of a recently published paper (\cite{balazs}), to which the
+new result following from the 2-sample Kolmogorov-Smirnov test is added, too.",9909379v1
+2000-05-02,Anisotropy of the Hubble Constant in a Cosmological Model with a Local Void on Scales of ~ 200 Mpc,"A spherical cosmological model with a local void on scales of $\sim 200$ Mpc
+and with an inhomogeneous Hubble constant was proposed in recent two papers.
+This model explains consistently the observed properties of the cosmic bulk
+flow, the accelerating behavior of type Ia supernovae and the CMB dipole
+anisotropy without invoking a cosmological constant. As we are in a position
+deviated from the center in the model, the anisotropy of the Hubble constant
+appears owing to the directional difference of the distance from the observer
+to the boundary of the void region. It is found that the anisotropy is
+maximally about 6% of the constant in the region of $200 \sim 500$ Mpc from us.
+This inhomogeneity and anisotropy of the Hubble constant are not so large as to
+be inconsistent with the present observation. The detection of this anisotropy
+in the future will be useful to clarify the implication of the inhomogeneity of
+the Hubble constant.",0005031v2
+2000-02-03,Band-theoretical prediction of magnetic anisotropy in uranium monochalcogenides,"Magnetic anisotropy of uranium monochalcogenides, US, USe and UTe, is studied
+by means of fully-relativistic spin-polarized band structure calculations
+within the local spin-density approximation. It is found that the size of the
+magnetic anisotropy is fairly large (about 10 meV/unit formula), which is
+comparable with experiment. This strong anisotropy is discussed in view of a
+pseudo-gap formation, of which crucial ingredients are the exchange splitting
+of U 5f states and their hybridization with chalcogen p states (f-p
+hybridization). An anomalous trend in the anisotropy is found in the series
+(US>>USe<UTe) and interpreted in terms of competition between localization of
+the U 5f states and the f-p hybridization. It is the spin-orbit interaction on
+the chalcogen p states that plays an essential role in enlarging the strength
+of the f-p hybridization in UTe, leading to an anomalous systematic trend in
+the magnetic anisotropy.",0002044v1
+2000-06-07,Theory of Magnetic Anisotropy in III_{1-x}Mn_{x}V Ferromagnets,"We present a theory of magnetic anisotropy in ${\rm III}_{1-x}{\rm
+Mn}_{x}{\rm V}$ diluted magnetic semiconductors with carrier-induced
+ferromagnetism. The theory is based on four and six band envelope functions
+models for the valence band holes and a mean-field treatment of their exchange
+interactions with ${\rm Mn}^{++}$ ions. We find that easy-axis reorientations
+can occur as a function of temperature, carrier density $p$, and strain. The
+magnetic anisotropy in strain-free samples is predicted to have a $p^{5/3}$
+hole-density dependence at small $p$, a $p^{-1}$ dependence at large $p$, and
+remarkably large values at intermediate densities. An explicit expression,
+valid at small $p$, is given for the uniaxial contribution to the magnetic
+anisotropy due to unrelaxed epitaxial growth lattice-matching strains. Results
+of our numerical simulations are in agreement with magnetic anisotropy
+measurements on samples with both compressive and tensile strains. We predict
+that decreasing the hole density in current samples will lower the
+ferromagnetic transition temperature, but will increase the magnetic anisotropy
+energy and the coercivity.",0006093v1
+2001-09-21,Hysteretic properties of a magnetic particle with strong surface anisotropy,"We study the influence of surface anisotropy on the zero-temperature
+hysteretic properties of a small single-domain magnetic particle, and give an
+estimation of the anisotropy constant for which deviations from the
+Stoner-Wohlfarth model are observed due to non-uniform reversal of the
+particle's magnetisation. For this purpose, we consider a spherical particle
+with simple cubic crystalline structure, a uniaxial anisotropy for core spins
+and radial anisotropy on the surface. The hysteresis loop is obtained by
+solving the local (coupled) Landau-Lifschitz equations for classical spin
+vectors. We find that when the surface anisotropy constant is at least of the
+order of the exchange coupling, large deviations are observed with respect to
+the Stoner-Wohlfarth model in the hysteresis loop and thereby the
+limit-of-metastability curve, since in this case the magnetisation reverses its
+direction in a non-uniform manner via a progressive switching of spin clusters.
+In this case the critical field, as a function of the particle's size, behaves
+as observed in experiments.",0109411v3
+2001-12-03,Effect of surface anisotropy on the hysteretic properties of a magnetic particle,"We study the influence of surface anisotropy on the zero-temperature
+hysteretic properties of a small single-domain magnetic particle, and give an
+estimation of the anisotropy constant for which deviations from the
+Stoner-Wohlfarth model are observed. We consider a spherical particle with
+simple cubic crystalline structure, a uniaxial anisotropy for core spins and
+radial anisotropy on the surface, and compute the hysteresis loop by solving
+the local Landau-Lifshitz equations for classical spin vectors. We find that
+when the surface anisotropy constant is at least of the order of the exchange
+coupling, large deviations are observed with respect to the Stoner-Wohlfarth
+model in the hysteresis loop and thereby the limit-of-metastability curve, due
+to the non-uniform cluster-wise reversal of the magnetisation.",0112032v1
+2002-07-14,Magnetoresistance and magnetic anisotropy in La$_{0.5}$Sr$_{0.5}$CoO$_{3-δ}$ film,"The magnetic and transport properties of La$_{0.5}$Sr$_{0.5}$CoO$_{3-\delta}$
+film grown on a LaAlO$_3$ substrate by pulsed-laser deposition are studied. The
+properties are found to be influenced by a combined influence of the magnetic
+anisotropy and inhomogeneity. Magnetoresistance anisotropy is determined by the
+shape anisotropy and the strain-induced magnetic anisotropy due to the
+film-substrate lattice interaction. Indications of the temperature-driven spin
+reorientation transition from an out-of plane orderded state at low
+temperatures to an in-plane ordered state at high temperatures as a result of
+competition between the mentioned anisotropy sources are found.",0207346v1
+2003-07-10,Axial and off-axial dynamic transitions in uniaxially anisotropic Heisenberg ferromagnet: A comparison,"Uniaxially anisotropic Heisenberg ferromagnet, in the presence of a magnetic
+fieldvarying sinusoidally in time, is studied by Monte Carlo Simulation. The
+axial (field applied only along the direction of anisotropy) and off-axial
+(field applied only along the direction which is prependicular to the direction
+of anisotropy) dynamic transitions are studied. By studying the distribution of
+the dynamic order parameter component, it is observed that the axial transition
+is discontinuous for low anisotropy and becomes continuous in high anisotropy.
+The off-axial transition is found to be continuous for all values of
+anisotropy. In the infinite anisotropy limit, both types of transitions are
+compared with athat observed in an Ising ferromagnet for the same value of the
+field and frequency. The infinitely anisotropic axial transition and dynamic
+transition in the Ising ferromagnet occur at different temperatures, whereas
+the infinitely anisotropic off-axial transition and the equilibrium ferro-para
+transition in the Ising model occur at the same temperature.",0307225v1
+2004-07-09,"Pressure Dependence of the Magnetic Anisotropy in the ""Single-Molecule Magnet"" [Mn4O3Br(OAc)3(dbm)3]","The anisotropy splitting in the ground state of the single-molecule magnet
+[Mn4O3Br(OAc)3(dbm)3] is studied by inelastic neutron scattering as a function
+of hydrostatic pressure. This allows a tuning of the anisotropy and thus the
+energy barrier for slow magnetisation relaxation at low temperatures. The value
+of the negative axial anisotropy parameter $D_{\rm cluster}$ changes from
+-0.0627(1) meV at ambient to -0.0603(3) meV at 12 kbar pressure, and in the
+same pressure range the height of the energy barrier between up and down spins
+is reduced from 1.260(5) meV to 1.213(9) meV. Since the $\rm Mn-Br$ bond is
+significantly softer and thus more compressible than the $\rm Mn-O$ bonds,
+pressure induces a tilt of the single ion Mn$^{3+}$ anisotropy axes, resulting
+in the net reduction of the axial cluster anisotropy.",0407235v1
+2005-04-14,Inversion phenomenon and phase diagram of the $S=1/2$ distorted diamond chain with the $XXZ$ interaction anisotropy,"We discuss the anisotropies of the Hamiltonian and the wave-function in an
+$S=1/2$ distorted diamond chain. The ground-state phase diagram of this model
+is investigated using the degenerate perturbation theory up to the first order
+and the level spectroscopy analysis of the numerical diagonalization data. In
+some regions of the obtained phase diagram, the anisotropy of the Hamiltonian
+and that of the wave-function are inverted, which we call inversion phenomenon;
+the N\'{e}el phase appears for the XY-like anisotropy and the spin-fluid phase
+appears for the Ising-like anisotropy. Three key words are important for this
+nature, which are frustration, the trimer nature, and the $XXZ$ anisotropy.",0504360v1
+2002-09-11,Semiclassical gravitation and quantization for the Bianchi type I universe with large anisotropy,"We use a perturbative method to evaluate the effective action of a free
+scalar field propagating in the Bianchi type I spacetime with large space
+anisotropy. The zeta- function regularization method is used to evaluate the
+action to the second order in the Schwinger perturbative formula. As the
+quantum corrections contain fourth derivative in the metric we apply the method
+of iterative reduction to reduce it to the second-order form to obtain the
+self-consistent solution of the semiclassical gravity theory, The reduced
+Einstein equation shows that the space anisotropy, which will be smoothed out
+during the evolution of universe, may play an important role in the dynamics of
+early universe. We quantize the corresponding minisuperspace model to
+investigate the behavior of the space anisotropy in the initial epoch. From the
+wavefunction of the Wheeler-DeWitt equation we see that the probability for the
+Bianchi type I spacetime with large anisotropy is less then that with a small
+anisotropy.",0209092v1
+2003-03-12,Cosmological Anisotropy and the Cycling of Universe,"In this paper, we analyze the anisotropy of the scale factor in the
+Kantowski-Sachs spacetime. We show that the anisotropy will not increase when
+the expansion rate is greater than certain values while it will increase when
+the expansion rate is less than that value or the Universe is contracting. It
+is manifested that the matter dominated and radiation dominated era favor the
+flat spacetime if the anisotropy does not develop significantly. The relation
+between the cosmological anisotropy and the red-shift of the supernovae, which
+could be used to verify the anisotropy through the observation, has been
+derived.",0303110v3
+2007-11-22,Globally Anisotropic High Porosity Silica Aerogels,"We discuss two methods by which high porosity silica aerogels can be
+engineered to exhibit global anisotropy. First, anisotropy can be introduced
+with axial strain. In addition, intrinsic anisotropy can result during growth
+and drying stages and, suitably controlled, it can be correlated with
+preferential radial shrinkage in cylindrical samples. We have performed small
+angle X-ray scattering (SAXS) to characterize these two types of anisotropy. We
+show that global anisotropy originating from either strain or shrinkage leads
+to optical birefringence and that optical cross-polarization studies are a
+useful characterization of the uniformity of the imposed global anisotropy.",0711.3495v1
+2008-02-28,"An extensive comparison of anisotropies in MBE grown (Ga,Mn)As material","This paper reports on a detailed magnetotransport investigation of the
+magnetic anisotropies of (Ga,Mn)As layers produced by various sources
+worldwide. Using anisotropy fingerprints to identify contributions of the
+various higher order anisotropy terms, we show that the presence of both a
+[100] and a [110] uniaxial anisotropy in addition to the primary ([100] +
+[010]) anisotropy is common to all medium doped (Ga,Mn)As layers typically used
+in transport measurement, with the amplitude of these uniaxial terms being
+characteristic of the individual layers.",0802.4206v1
+2008-05-21,Friedel oscillations induced surface magnetic anisotropy,"We present detailed numerical studies of the magnetic anisotropy energy of a
+magnetic impurity near the surface of metallic hosts (Au and Cu), that we
+describe in terms of a realistic tight-binding surface Green's function
+technique. We study the case when spin-orbit coupling originates from the
+d-band of the host material and we also investigate the case of a strong local
+spin-orbit coupling on the impurity itself. The splitting of the impurity's
+spin-states is calculated to leading order in the exchange interaction between
+the impurity and the host atoms using a diagrammatic Green's function
+technique. The magnetic anisotropy constant is an oscillating function of the
+separation d from the surface: it asymptotically decays as 1/d2 and its
+oscillation period is determined by the extremal vectors of the host's Fermi
+Surface. Our results clearly show that the host-induced magnetic anisotropy
+energy is by several orders of magnitude smaller than the anisotropy induced by
+the local mechanism, which provides sufficiently large anisotropy values to
+explain the size dependence of the Kondo resistance observed experimentally.",0805.3275v1
+2008-05-28,Primordial statistical anisotropy generated at the end of inflation,"We present a new mechanism for generating primordial statistical anisotropy
+of curvature perturbations. We introduce a vector field which has a non-minimal
+kinetic term and couples with a waterfall field in hybrid inflation model. In
+such a system, the vector field gives fluctuations of the end of inflation and
+hence induces a subcomponent of curvature perturbations. Since the vector has a
+preferred direction, the statistical anisotropy could appear in the
+fluctuations. We present the explicit formula for the statistical anisotropy in
+the primordial power spectrum and the bispectrum of curvature perturbations.
+Interestingly, there is the possibility that the statistical anisotropy does
+not appear in the power spectrum but does appear in the bispectrum. We also
+find that the statistical anisotropy provides the shape dependence to the
+bispectrum.",0805.4265v6
+2008-06-15,Tricritical transition in the classical XY model on Kagomé lattice under local anisotropy,"Using mean-field theory and high resolution Monte Carlo simulation technique
+based on multi-histogram method, we have investigated the critical properties
+of an antiferromagnetic XY model on the 2D Kagom\'e lattice, with single ion
+easy-axes anisotropy. The mean-field theory predicts second-order phase
+transition from disordered to all-in all-out state for any value of anisotropy
+for this model. However, Monte Carlo simulations result in first order
+transition for small values of anisotropy which turns to second order with
+increasing strength of anisotropy, indicating the existence of a tricritical
+point for this model. The critical exponents, obtained by finite-size scaling
+methods, show that the transition is in Ising universality class for large
+values of anisotropy, while the critical behaviour of the system deviates from
+2D-$\phi^6$ model near the tricritical point. This suggests the possibility for
+existence of a new tricritical universality in two-dimensions.",0806.2432v1
+2008-11-19,Transport Anisotropy as a Probe of the Interstitial Vortex State in Superconductors with Artificial Pinning Arrays,"We show using simulations that when interstitial vortices are present in
+superconductors with periodic pinning arrays, the transport in two
+perpendicular directions can be anisotropic. The degree of the anisotropy
+varies as a function of field due to the fact that the interstitial vortex
+lattice has distinct orderings at different matching fields. The anisotropy is
+most pronounced at the matching fields but persists at incommensurate fields,
+and it is most prominent for triangular, honeycomb, and kagome pinning arrays.
+Square pinning arrays can also show anisotropic transport at certain fields in
+spite of the fact that the perpendicular directions of the square pinning array
+are identical. We show that the anisotropy results from distinct vortex
+dynamical states and that although the critical depinning force may be lower in
+one direction, the vortex velocity above depinning may also be lower in the
+same direction for ranges of external drives where both directions are
+depinned. For honeycomb and kagome pinning arrays, the anisotropy can show
+multiple reversals as a function of field. We argue that when the pinning sites
+can be multiply occupied such that no interstitial vortices are present, the
+anisotropy is strongly reduced or absent.",0811.3178v1
+2008-11-25,Evidence for two distinct anisotropies in the oxypnictide superconductors SmFeAsO_(0.8)F_(0.2) and NdFeAsO_(0.8)F_(0.2),"Single crystals of the oxypnictide superconductors SmFeAsO_(0.8)F_(0.2) and
+NdFeAsO_(0.8)F_(0.2) with T_c in the range of 44 K to 48 K were investigated by
+torque magnetometry. An analysis of the data in terms of a recently proposed
+model for the anisotropic magnetization in the superconducting state, treating
+the penetration depth anisotropy differently than the upper critical field
+anisotropy, provides evidence that in the oxypnictide superconductors two
+distinct anisotropies are present. As a result the penetration depth anisotropy
+differs significantly in magnitude and in temperature dependence from the upper
+critical field anisotropy, analogous to MgB_2 but with a reversed sign of
+slope. This scenario strongly suggests a new multi-band mechanism in the novel
+class of oxypnictide high-temperature superconductors.",0811.4047v3
+2009-09-11,Consistency criteria for generalized Cuddeford systems,"General criteria to check the positivity of the distribution function
+(phase-space consistency) of stellar systems of assigned density and anisotropy
+profile are useful starting points in Jeans-based modeling. Here we
+substantially extend previous results, and we present the inversion formula and
+the analytical necessary and sufficient conditions for phase-space consistency
+of the family of multi-component Cuddeford spherical systems: the distribution
+function of each density component of these systems is defined as the sum of an
+arbitrary number of Cuddeford distribution functions with arbitrary values of
+the anisotropy radius, but identical angular momentum exponent. The radial
+trend of anisotropy that can be realized by these models is therefore very
+general. As a surprising by-product of our study, we found that the ``central
+cusp-anisotropy theorem'' (a necessary condition for consistency relating the
+values of the central density slope and of the anisotropy parameter) holds not
+only at the center, but at all radii in consistent multi-component generalized
+Cuddeford systems. This last result suggests that the so--called
+mass--anisotropy degeneracy could be less severe than what is sometimes feared.",0909.2156v1
+2010-08-30,Searches for Cosmic-Ray Electron Anisotropies with the Fermi Large Area Telescope,"The Large Area Telescope on board the \textit{Fermi} satellite
+(\textit{Fermi}-LAT) detected more than 1.6 million cosmic-ray
+electrons/positrons with energies above 60 GeV during its first year of
+operation. The arrival directions of these events were searched for
+anisotropies of angular scale extending from $\sim$ 10 $^\circ$ up to
+90$^\circ$, and of minimum energy extending from 60 GeV up to 480 GeV. Two
+independent techniques were used to search for anisotropies, both resulting in
+null results. Upper limits on the degree of the anisotropy were set that
+depended on the analyzed energy range and on the anisotropy's angular scale.
+The upper limits for a dipole anisotropy ranged from $\sim0.5%$ to $\sim10%$.",1008.5119v3
+2010-09-13,Radiative energy loss in an anisotropic Quark-Gluon-Plasma,"We calculate radiative energy loss of heavy and light quarks in anisotropic
+medium (static) in first order opacity expansion. Such an anisotropy can result
+from the initial rapid longitudinal expansion of the matter, created in
+relativistic heavy ion collisions. Significant dependency of the energy loss on
+the anisotropy parameter ($\xi$) and the direction of propagation of the
+partons with respect to the anisotropy axis is found. It is shown that the
+introduction of early time momentum-space anisotropy can enhance the fractional
+energy loss in the direction of the anisotropy, whereas it decreases when the
+parton propagates perpendicular to the direction of the anisotropy.",1009.2304v3
+2010-10-01,Ferromagnetic resonance study of Co/Pd/Co/Ni multilayers with perpendicular anisotropy irradiated with Helium ions,"We present a ferromagnetic resonance (FMR) study of the effect of Helium ion
+irradiation on the magnetic anisotropy, the linewidth and the Gilbert damping
+of a Co/Ni multilayer coupled to Co/Pd bilayers. The perpendicular magnetic
+anisotropy decreases linearly with He ion fluence, leading to a transition to
+in-plane magnetization at a critical fluence of 5x10^{14} ions/cm^2. We find
+that the damping is nearly independent of fluence but the FMR linewidth at
+fixed frequency has a maximum near the critical fluence, indicating that the
+inhomogeneous broadening of the FMR line is a non-monotonic function of the He
+ion fluence. Based on an analysis of the angular dependence of the FMR
+linewidth, the inhomogeneous broadening is associated with spatial variations
+in the magnitude of the perpendicular magnetic anisotropy. These results
+demonstrate that ion irradiation may be used to systematically modify the
+magnetic anisotropy and distribution of magnetic anisotropy parameters of
+Co/Pd/Co/Ni multilayers for applications and basic physics studies.",1010.0268v2
+2010-12-13,Distinct electronic nematicities between electron and hole underdoped iron pnictides,"We systematically investigated the in-plane resistivity anisotropy of
+electron-underdoped $EuFe_{2-x}Co_xAs_2$ and $BaFe_{2-x}Co_xAs_2$, and
+hole-underdoped $Ba_{1-x}K_xFe_2As_2$. Large in-plane resistivity anisotropy
+was found in the former samples, while {\it tiny} in-plane resistivity
+anisotropy was detected in the latter ones. When it is detected, the anisotropy
+starts above the structural transition temperature and increases smoothly
+through it. As the temperature is lowered further, the anisotropy takes a
+dramatic enhancement through the magnetic transition temperature. We found that
+the anisotropy is universally tied to the presence of non-Fermi liquid T-linear
+behavior of resistivity. Our results demonstrate that the nematic state is
+caused by electronic degrees of freedom, and the microscopic orbital
+involvement in magnetically ordered state must be fundamentally different
+between the hole and electron doped materials.",1012.2731v1
+2011-06-20,Effects of Single-site Anisotropy on Mixed Diamond Chains with Spins 1 and 1/2,"Effects of single-site anisotropy on mixed diamond chains with spins 1 and
+1/2 are investigated in the ground states and at finite temperatures. There are
+phases where the ground state is a spin cluster solid, i.e., an array of
+uncorrelated spin-1 clusters separated by singlet dimers. The ground state is
+nonmagnetic for the easy-plane anisotropy, while it is paramagnetic for the
+easy-axis anisotropy. Also, there are the N\'eel, Haldane, and large-$D$
+phases, where the ground state is a single spin cluster of infinite size and
+the system is equivalent to the spin-1 Heisenberg chain with alternating
+anisotropy. The longitudinal and transverse susceptibilities and entropy are
+calculated at finite temperatures in the spin-cluster-solid phases. Their
+low-temperature behaviors are sensitive to anisotropy.",1106.3846v2
+2011-07-30,Comprehensive Control of Optical Polarization Anisotropy in Semiconducting Nanowires,"The demonstration of strong photoluminescence polarization anisotropy in
+semiconducting nanowires embodies both technological promise and scientific
+challenge. Here we present progress on both fronts through the study of the
+photoluminescence polarization anisotropy of randomly oriented nanowire
+ensembles in materials without/with crystalline anisotropy, small/wide bandgap,
+and both III-V/II-VI chemistry (InP/ZnO nanowires, respectively). Comprehensive
+control of the polarization anisotropy is realized by dielectric matching with
+conformally deposited Ta2O5 (dielectric ratios of 9.6:4.41 and 4.0:4.41 for InP
+and ZnO, respectively). After dielectric matching, the polarization anisotropy
+of the nanowire ensembles is reduced by 86% for InP:Ta2O5 and 84% for
+ZnO:Ta2O5.",1108.0033v1
+2011-09-11,Mössbauer study of the field induced uniaxial anisotropy in electro-deposited FeCo alloy films,"Thin ferromagnetic films with in-plane magnetic anisotropy are promising
+materials for obtaining high microwave permeability. The paper reports on the
+M\""ossbauer study of the field induced in-plane uniaxial anisotropy in
+electro-deposited $FeCo$ alloy films. The $FeCo$ alloy films have been prepared
+by electro-deposition method with and without external magnetic field applied
+parallel to the film plane during deposition. The vibrating sample magnetometry
+and M\""ossbauer spectroscopy measurements at room temperature indicate that the
+film deposited in external field shows an in-plane uniaxial anisotropy with an
+easy direction coincides with the external field direction and a hard direction
+perpendicular to the field direction, whereas the film deposited without
+external field doesn't show any in-plane anisotropy. M\""ossbauer spectra taken
+in three geometric arrangements show that the magnetic moments are almost
+constrained in the film plane for the film deposited with applied magnetic
+field. And the magnetic moments are tend to align in the direction of the
+applied external magnetic field during deposition, indicating that the observed
+anisotropy should be attributed to directional ordering of atomic pairs.",1109.2286v1
+2011-11-10,Local Magnetic Turbulence and TeV-PeV Cosmic Ray Anisotropies,"In the energy range from ~ 10^12 eV to ~ 10^15 eV, the Galactic cosmic ray
+flux has anisotropies both on large scales, with an amplitude of the order of
+0.1%, and on scales between ~ 10 and ~ 30 degrees, with amplitudes smaller by a
+factor of a few. With a diffusion coefficient inferred from Galactic cosmic ray
+chemical abundances, the diffusion approximation predicts a dipolar anisotropy
+of comparable size, but does not explain the smaller scale anisotropies. We
+demonstrate here that energy dependent smaller scale anisotropies naturally
+arise from the local concrete realization of the turbulent magnetic field
+within the cosmic ray scattering length. We show how such anisotropies could be
+calculated if the magnetic field structure within a few tens of parsecs from
+Earth were known.",1111.2536v2
+2012-01-19,"Local Anisotropy, Higher Order Statistics, and Turbulence Spectra","Correlation anisotropy emerges dynamically in magnetohydrodynamics (MHD),
+producing stronger gradients across the large-scale mean magnetic field than
+along it. This occurs both globally and locally, and has significant
+implications in space and astrophysical plasmas, including particle scattering
+and transport, and theories of turbulence. Properties of local correlation
+anisotropy are further documented here by showing through numerical experiments
+that the effect is intensified in more localized estimates of the mean field.
+The mathematical formulation of this property shows that local anisotropy mixes
+second-order with higher order correlations. Sensitivity of local statistical
+estimates to higher order correlations can be understood in connection with the
+stochastic coordinate system inherent in such formulations. We demonstrate this
+in specific cases, illustrate the connection to higher order statistics by
+showing the sensitivity of local anisotropy to phase randomization, and thus
+establish that the local structure function is not a measure of the energy
+spectrum. Evidently the local enhancement of correlation anisotropy is of
+substantial fundamental interest, and this phenomenon must be understood in
+terms of higher order correlations, fourth-order and above.",1201.4127v1
+2012-05-08,Anisotropy of strong pinning in multi-band superconductors,"The field-angular dependence and anisotropy of the critical current density
+in iron-based superconductors is evaluated using a phenomenological approach
+featuring distinct anisotropy factors for the penetration depth and the
+coherence length. Both the weak collective pinning limit, and the strong
+pinning limit relevant for iron-based superconductors at low magnetic fields
+are considered. It is found that in the more anisotropic materials, such as
+SmFeAsO and NdFeAsO, the field-angular dependence is completely dominated by
+the coherence-length (upper-critical field) anisotropy, thereby explaining
+recent results on the critical current in these materials. In less anisotropic
+superconductors, strong pinning can lead to an apparent inversion of the
+anisotropy. Finally, it is shown that, under all circumstances, the ratio of
+c-axis and ab-plane critical current densities for magnetic field along the
+ab-plane directly yields the coherence length anisotropy factor
+{\epsilon}{\xi}.",1205.1741v3
+2012-08-08,Anisotropy of the in-plane resistivity of underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ superconductors induced by impurity scattering in the antiferromagnetic orthorhombic phase,"We investigated the in-plane resistivity anisotropy for underdoped
+Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals with improved quality. We
+demonstrate that the anisotropy in resistivity in the magnetostructural ordered
+phase arises from the anisotropy in the residual component which increases in
+proportion to the Co concentration $x$. This gives evidence that the anisotropy
+originates from the impurity scattering by Co atoms substituted for the Fe
+sites, rather than so far proposed mechanism such as the anisotropy of Fermi
+velocities of reconstructed Fermi surface pockets. As doping proceeds to the
+paramagnetic-tetragonal phase, a Co impurity transforms to a weak and isotropic
+scattering center.",1208.1575v2
+2012-09-24,Field Dependence of the Superconducting Basal Plane Anisotropy of TmNi2B2C,"The superconductor TmNi2B2C possesses a significant four-fold basal plane
+anisotropy, leading to a square Vortex Lattice (VL) at intermediate fields.
+However, unlike other members of the borocarbide superconductors, the
+anisotropy in TmNi2B2C appears to decrease with increasing field, evident by a
+reentrance of the square VL phase. We have used Small Angle Neutron Scattering
+measurements of the VL to study the field dependence of the anisotropy. Our
+results provide a direct, quantitative measurement of the decreasing
+anisotropy. We attribute this reduction of the basal plane anisotropy to the
+strong Pauli paramagnetic effects observed in TmNi2B2C and the resulting
+expansion of vortex cores near Hc2.",1209.5414v1
+2012-10-26,Novel Techniques for Decomposing Diffuse Backgrounds,"The total anisotropy of a diffuse background composed of two or more sources,
+such as the Fermi-LAT--measured gamma-ray background, is set by the anisotropy
+of each source population and the contribution of each population to the total
+intensity. The total anisotropy as a function of energy (the anisotropy energy
+spectrum) will modulate as the relative contributions of the sources change,
+implying that the anisotropy energy spectrum also encodes the intensity
+spectrum of each source class. We develop techniques, applicable to any such
+diffuse background, for unraveling the intensity spectrum of each component
+source population given a measurement of the total intensity spectrum and the
+total anisotropy energy spectrum, without introducing \emph{a priori}
+assumptions about the spectra of the source classes. We demonstrate the
+potential of these methods by applying them to example scenarios for the
+composition of the Fermi-LAT gamma-ray background consistent with current data
+and feasible within 10 years of observation.",1210.7239v2
+2012-11-29,"Electric-field control of the magnetic anisotropy in an ultrathin (Ga,Mn)As/(Ga,Mn)(As,P) bilayer","We report on the electric control of the magnetic anisotropy in an ultrathin
+ferromagnetic (Ga,Mn)As/(Ga,Mn)(As,P) bilayer with competing in-plane and
+out-of-plane anisotropies. The carrier distribution and therefore the strength
+of the effective anisotropy is controlled by the gate voltage of a field effect
+device. Anomalous Hall Effect measurements confirm that a depletion of carriers
+in the upper (Ga,Mn)As layer results in the decrease of the in-plane
+anisotropy. The uniaxial anisotropy field is found to decrease by a factor ~ 4
+over the explored gate-voltage range, so that the transition to an out-of-plane
+easy-axis configuration is almost reached.",1211.7055v1
+2013-02-10,Measurement of orbital asymmetry and strain in Co90Fe10/Ni multilayers and alloys: Origins of perpendicular anisotropy,"We use broadband ferromagnetic resonance spectroscopy and x-ray diffraction
+to investigate the fundamental origin of perpendicular anisotropy in
+Co90Fe10/Ni multilayers. By careful evaluation of the spectroscopic g-factor,
+we determine the orbital moment along the out-of-plane and in-plane directions.
+For the multilayers, we find a direct relationship between the orbital moment
+asymmetry and the perpendicular anisotropy, consistent with the theory of Bruno
+[P.Bruno, Phys. Rev. B, 39, 865 (1989)]. A systematic x-ray diffraction study
+revealed the presence of a trigonal strain as high as 0.7 % in some samples.
+However, we found no direct correlation between the strain and the anisotropy,
+indicating that the anisotropy is not dominated by magnetoelastic effects. In
+order to further study the interface structure on the anisotropy, we prepared a
+set of equivalent alloy samples. The strain in the alloy samples was comparable
+to that of the multilayer samples; however the orbital moment asymmetry in the
+alloy samples showed a very different trend allowing us to isolate the effect
+of the interfaces in the multilayers.",1302.2366v1
+2013-03-21,Asymptotic Preserving scheme for strongly anisotropic parabolic equations for arbitrary anisotropy direction,"This paper deals with the numerical study of a strongly anisotropic heat
+equation. The use of standard schemes in this situation leads to poor results,
+due to the high anisotropy. Furthermore, the recently proposed
+Asymptotic-Preserving method [arXiv:1203.6739] allows to perform simulations
+regardless of the anisotropy strength but its application is limited to the
+case, where the anisotropy direction is given by a field with all field lines
+open. In this paper we introduce a new Asymptotic-Preserving method, which
+overcomes those limitations without any loss of precision or increase in the
+computational costs. The convergence of the method is shown to be independent
+of the anisotropy parameter $0 < \eps <1$, and this for fixed coarse Cartesian
+grids and for variable anisotropy directions. The context of this work are
+magnetically confined fusion plasmas.",1303.5219v3
+2013-08-01,"Observation of TeV-PeV cosmic ray anisotropy with IceCube, IceTop and AMANDA","The study of cosmic ray anisotropy in the TeV-PeV energy range could provide
+clues about the origin and propagation of cosmic rays in our galactic
+neighborhood. Because the observed anisotropy is very small, below the
+per-mille level, large event volumes are needed in order to characterize it in
+sufficient detail. Over the last six years, the IceCube Observatory has
+collected 150 billion cosmic ray induced muon events. This large data sample
+made it possible to detect anisotropies in the southern hemisphere, down to the
+10$^{-5}$ level, at primary energies in excess of 10 TeV. The observed
+anisotropy is not a simple dipole, but it can be described as composed of
+multipole components of the spherical harmonic expansion, to about
+10$^{\circ}$. A change in topological structure of the cosmic ray arrival
+distribution is observed above 100 TeV. Data collected with the air shower
+array IceTop above 300 TeV confirm the observations up to the PeV energy scale.
+Moreover, the addition of data collected with the AMANDA neutrino telescope,
+which operated between 2000 and 2007, has enabled us to search for time
+variability in the observed TeV anisotropy.",1308.0246v1
+2013-08-13,Anatomy of perpendicular magnetic anisotropy in Fe/MgO magnetic tunnel junctions: First principles insight,"Using first-principles calculations, we elucidate microscopic mechanisms of
+perpendicular magnetic anisotropy (PMA)in Fe/MgO magnetic tunnel junctions
+through evaluation of orbital and layer resolved contributions into the total
+anisotropy value. It is demonstrated that the origin of the large PMA values is
+far beyond simply considering the hybridization between Fe-3d$ and O-2p
+orbitals at the interface between the metal and the insulator. On-site
+projected analysis show that the anisotropy energy is not localized at the
+interface but it rather propagates into the bulk showing an attenuating
+oscillatory behavior which depends on orbital character of contributing states
+and interfacial conditions. Furthermore, it is found in most situations that
+states with $d_{yz(xz)}$ and $d_{z^2}$ character tend always to maintain the
+PMA while those with $d_{xy}$ and $d_{x^2-y^2}$ character tend to favor the
+in-plane anisotropy. It is also found that while MgO thickness has no influence
+on PMA, the calculated perpendicular magnetic anisotropy oscillates as a
+function of Fe thickness with a period of 2ML and reaches a maximum value of
+3.6 mJ/m$^2$.",1308.2909v1
+2013-09-05,Voltage-induced strain control of the magnetic anisotropy in a Ni thin film on flexible substrate,"Voltage-induced magnetic anisotropy has been quantitatively studied in
+polycrystalline Ni thin film deposited on flexible substrate using microstrip
+ferromagnetic resonance. This anisotropy is induced by a piezoelectric actuator
+on which the film/substrate system was glued. In our work, the control of the
+anisotropy through the applied elastic strains is facilitated by the compliant
+elastic behavior of the substrate. The in-plane strains in the film induced by
+the piezoelectric actuation have been measured by the digital image correlation
+technique. Non-linear variation of the resonance field as function of the
+applied voltage is found and well reproduced by taking into account the non
+linear and hysteretic variations of the induced in-plane strains as function of
+the applied voltage. Moreover, we show that initial uniaxial anisotropy
+attributed to compliant substrate curvature is fully compensated by the voltage
+induced anisotropy.",1309.1417v1
+2013-12-23,Implications of primordial power spectra with statistical anisotropy on CMB temperature fluctuation and polarizations,"Both the Wilkinson Microwave Anisotropy Probe (WMAP) and Planck observations
+reported the hemispherical asymmetry of the cosmic microwave background (CMB)
+temperature fluctuation. The hemispherical asymmetry might be stemmed from the
+primordial statistical anisotropy during the inflationary era of the universe.
+In this paper, we study possible implications of the primordial power spectra
+with dipolar anisotropy on the CMB temperature fluctuation and polarizations.
+We explicitly show that the statistical dipolar anisotropy may induce the
+off-diagonal (\(\ell'\neq\ell\)) $TT$, $EE$, $BB$, and $TE$ correlations, as
+well as the diagonal (\(\ell'=\ell\)) $TB$ and $EB$ spectra. In particular,
+these correlation coefficients are expected to be \(m\)-dependent generically.
+These signals of statistical anisotropy might be tested by CMB observations in
+future.",1312.6575v2
+2014-02-28,Anisotropic optical properties of Fe/GaAs(001) nanolayers from first principles,"We investigate the anisotropy of the optical properties of thin Fe films on
+GaAs(001) from first-principles calculations. Both intrinsic and
+magnetization-induced anisotropy are covered by studying the system in the
+presence of spin-orbit coupling and external magnetic fields. We use the
+linearized augmented plane wave method, as implemented in the WIEN2k density
+functional theory code, to show that the $C_{2v}$ symmetric anisotropy of the
+spin-orbit coupling fields at the Fe/GaAs(001) interface manifests itself in
+the corresponding anisotropy of the optical conductivity and the polar
+magneto-optical Kerr effect. While their magnetization-induced anisotropy is
+negligible, the intrinsic anisotropy of the optical properties is significant
+and reflects the underlying $C_{2v}$ symmetry of the Fe/GaAs(001) interface.
+This suggests that the effects of anisotropic spin-orbit coupling fields in
+experimentally relevant Fe/GaAs(001) slabs can be studied by purely optical
+means.",1402.7370v1
+2014-03-28,On radial anisotropy limits in stellar systems,"Following earlier authors, we re-examine constraints on the radial velocity
+anisotropy of generic stellar systems using arguments for phase space density
+positivity, stability, and separability. It is known that although the majority
+of commonly used systems have an maximum anisotropy of less than half of the
+logarithmic density slope \emph{i.e.} $\beta < \gamma/2$, there are exceptions
+for separable models with large central anisotropy. Here we present a new
+exceptional case with above-threshold anisotropy locally but with an isotropic
+center nevertheless. These models are non-separable and we maintain positivity.
+Our analysis suggests that regions of above-threshold anisotropy are more
+related to regions of possible secular instability, which might be observed in
+self-consistent galaxies in a short-lived phase. s an equilibrium solution for
+a collisionless system.",1403.7396v2
+2014-05-19,An observable electron-positron anisotropy cannot be generated by dark matter,"I demonstrate that if an anisotropy in the arrival direction of high-energy
+cosmic-ray electrons and positrons is observed then, barring local anisotropic
+diffusion, dark matter annihilation is ruled out as an explanation to the
+positron excess. For an observable anisotropy to originate from dark matter
+annihilation, the high-energy electrons and positrons must be produced in a
+nearby clump. I consider the annihilation pathway producing the smallest flux
+of gamma rays versus electrons and positrons, and the combination of clump
+distance and luminosity that minimizes the gamma-ray flux. I show that if an
+anisotropy from such a clump were detected, and if such anisotropy did not
+generate from anisotropic diffusion effects, then the clump would be clearly
+detectable as an anomalous, bright gamma-ray source with the Fermi Large Area
+Telescope. I also point out that the non-detection of an anisotropy is
+perfectly compatible with an astrophysical origin for the excess positrons that
+has nothing to do with dark matter.",1405.4884v2
+2014-05-20,Resistive anisotropy due to spin-fluctuation scattering in the nematic phase of iron pnictides,"The large in-plane anisotropy of the resistivity is a hallmark of the nematic
+state of the iron pnictides. Solving the Boltzmann transport equation, we show
+that the prominent doping dependence as well as the large values of the
+anisotropy can be well explained by momentum-dependent spin-fluctuation
+scattering without assuming anisotropic impurity states. Due to the
+forward-scattering corrections, the hot spots contribute to the resistive
+anisotropy even in the case of strong spin fluctuations, which makes large
+values of the anisotropy possible. The ellipticity of the electron pockets
+plays an important role in explaining the dominance of positive values of the
+anisotropy, i.e., larger resistivity in the direction with weaker spin
+fluctuations, throughout the doping range.",1405.5084v3
+2014-07-03,Magnetic fields and cosmic ray anisotropies at TeV energies,"Several cosmic-ray observatories have provided a high accuracy map of the sky
+at TeV--PeV energies. The data reveals an O(0.1%) deficit from north galactic
+directions that peaks at 10 TeV and then evolves with the energy, together with
+other anisotropies at smaller angular scales. Using Boltzmann's equation we
+derive expressions for the cosmic-ray flux that fit most of these features. The
+anisotropies depend on the local interstellar magnetic field B_{IS}, on the
+average galactic field B_{R} in our vicinity, and on the distribution of
+dominant cosmic-ray sources. We show that the initial dipole anisotropy along
+B_{IS} can be modulated by changes in the global cosmic ray wind, and that a
+variation in the dipole direction would imply a given radius of coherence for
+B_{IS}. We also show that small and medium-scale anisotropies may appear when
+the full-sky anisotropy finds a turbulence acting as a magnetic lens.",1407.0850v3
+2014-07-09,AC susceptibility of an assembly of nanomagnets: combined effects of surface anisotropy and dipolar interactions,"We compute the AC susceptibility of a weakly dipolar-interacting monodisperse
+assembly of magnetic nanoclusters with oriented anisotropy. For this purpose we
+first compute the relaxation rate in a longitudinal magnetic field of a single
+nanomagnet taking account of both dipolar interactions in the case of dilute
+assemblies and surface anisotropy. We then study the behavior of the real and
+imaginary components of the AC susceptibility as functions of temperature,
+frequency, surface anisotropy and inter-particle interactions. We find that the
+surface anisotropy induces an upward shift of the temperature at the maximum of
+the AC susceptibility components and that its effects may be tuned so as to
+screen out the effects of interactions. The phenomenological Vogel-Fulcher law
+for the effect of dipolar interaction on the relaxation rate is revisited
+within our formalism and a semi-analytical expression is given for the
+effective temperature is given in terms of inter alia the applied field,
+surface anisotropy and dipolar interaction.",1407.2503v2
+2014-12-18,Can galactic dark matter substructure contribute to the cosmic gamma-ray anisotropy?,"The annihilation of dark matter (DM) particles in the Milky Way can
+contribute to the diffuse gamma-ray background (DGRB). Due to the presence of
+substructures, this emission will appear anisotropic in a predictable way. We
+generate full-sky maps of the gamma-ray emission in galactic substructures from
+results of the high-resolution Via Lactea II N-body simulation of the Milky Way
+DM halo. We calculate the anisotropy pattern, taking into account different
+radial profiles of the DM distribution in substructures, cosmic variance, and
+the detection threshold, and compare it to the anisotropy in the DGRB observed
+by the Fermi Large Area Telescope (LAT). By comparing the upper limits on the
+DM self-annihilation cross-section, <$\sigma v$>, implied by the anisotropy to
+the intensity of the DGRB and detected sources in the LAT 2-yr Point Source
+Catalog, we find that galactic substructure cannot contribute to the
+anisotropies in the DGRB without strongly violating these observations. Our
+results challenge the perception that small-scale anisotropies in the DGRB can
+be used as a probe of DM annihilation in galactic subhaloes.",1412.5749v1
+2015-01-26,Vortex Polarity Switching in Magnets with Surface Anisotropy,"Vortex core reversal in magnetic particle is essentially influenced by a
+surface anisotropy. Under the action of a perpendicular static magnetic field
+the vortex core undergoes a shape deformationof pillow- or barrel-shaped type,
+depending on the type of the surface anisotropy. This deformation plays a key
+point in the switching mechanism: We predict that the vortex polarity switching
+is accompanied (i) by a linear singularity in case of Heisenberg magnet with
+bulk anisotropy only and (ii) by a point singularities in case of surface
+anisotropy or exchange anisotropy. We study in details the switching process
+using spin-lattice simulations and propose a simple analytical description
+using a wired core model, which provides an adequate description of the Bloch
+point statics, its dynamics and the Bloch point mediated switching process. Our
+analytical predictions are confirmed by spin-lattice simulations for Heisenberg
+magnet and micromagnetic simulations for nanomagnet with account of a dipolar
+interaction.",1501.06548v1
+2015-02-04,Is inner core seismic anisotropy a marker of plastic flow of cubic iron?,"This paper investigates whether observations of seismic anisotropy are
+compatible with a cubic structure of the inner core Fe alloy. We assume that
+anisotropy is the result of plastic deformation within a large scale flow
+induced by preferred growth at the inner core equator. Based on elastic moduli
+from the literature, bcc- or fcc-Fe produce seismic anisotropy well below
+seismic observations ($\textless{}0.4\%$). A Monte-Carlo approach allows us to
+generalize this result to any form of elastic anisotropy in a cubic system.
+Within our model, inner core global anisotropy is not compatible with a cubic
+structure of Fe alloy. Hence, if the inner core material is indeed cubic, large
+scale coherent anisotropic structures, incompatible with plastic deformation
+induced by large scale flow, must be present.",1502.01270v1
+2015-04-26,Gaussian Anisotropy In Strange Quark Stars,"In this paper for studying the anisotropic strange quark stars, we assume
+that the radial pressure inside the anisotropic star is a superposition of
+pressure in an isotropic case plus a Gaussian perturbation term. Considering a
+proportionality between electric charge density and the density of matter, we
+solve the TOV equation for different cases numerically. Our results indicate
+that anisotropy increases the maximum mass $M_{max}$ and also its corresponding
+radius $R$ for a typical strange quark star. According to our calculations, an
+anisotropy amplitude of $A=3\times10^{33}Nm^{-2}$ with a standard deviation of
+$\sigma=3\times10^{3}m$ leads to a neutron star of 1.97$M_{\odot}$.
+Furthermore, electric charge not only increases the maximum mass and its
+corresponding radius, but also raises up the anisotropy factor. We can see that
+the tangential pressure $p_{t}$ and anisotropy factor $\Delta$ unlike the
+radial pressure $p_{r}$ have a maximum on the surface and this maximum
+increases by adding electric charge effect. However, we show that anisotropy
+can be more effective than electric charge in rasing maximum mass of strange
+quark stars.",1504.06805v1
+2015-07-02,Magnetic anisotropy energy in disordered Ge_{1-x}Mn_{x}Te,"We theoretically analyze the influence of chemical disorder on magnetic
+anisotropy in Ge_{1-x}Mn_{x}Te semiconductor layers known to exhibit
+carrier-induced ferromagnetism and ferroelectric distortion of rhombohedral
+crystal lattice. Using DFT method we determine the local changes in the crystal
+structure due to Mn ions substitution for Ge and due to the presence in
+Ge_{1-x}Mn_{x}Te of very high concentration of cation vacancies. We calculate
+the effect of this structural and chemical disorder on single ion magnetic
+anisotropy mechanism and show that its contribution is order of magnitude
+smaller as compared to magnetic anisotropy mechanism originating from the spin
+polarization induced by Mn ions into neighboring Te and Ge ions. We also
+discuss magnetic anisotropy effects due to pairs of Mn ions differently
+allocated in the lattice. The spatial averaging over chemical disorder strongly
+reduces the strength of this magnetic anisotropy mechanism and restores the
+global rhombohedral symmetry of magnetic system.",1507.00762v1
+2015-09-01,Generalization of the van der Waals equation for anisotropic fluids in porous media,"The generalized van der Waals equation of state for anisotropic liquids in
+porous media consists of two terms.One of them is based on the equation of
+state for hard spherocylinders in random porous media obtained from the scaled
+particle theory.The second term is expressed in terms of the mean value of
+attractive intermolecular interactions.The obtained equation is used for the
+investigation of the gas-liquid-nematic phase behavior of a molecular system
+depending on the anisotropy of molecule shapes, anisotropy of attractive
+intermolecular interactions, and porosity of a porous medium.It is shown that
+the anisotropic phase is formed by the anisotropy of attractive intermolecular
+interactions and by the anisotropy of molecular shapes.The anisotropy of
+molecular shapes shifts the phase diagram to lower densities and higher
+temperatures.The anisotropy of attractive interactions widens significantly the
+coexistence region between the isotropic and anisotropic phases and shifts it
+to the region of lower densities and higher temperatures.It is shown that, for
+sufficiently long spherocylinders, the liquid-gas transition is localized
+completely within the nematic region.For all the considered cases, the decrease
+of the porosity shifts the phase diagram to the region of lower densities and
+lower temperatures.",1509.00242v1
+2015-09-22,Nonlocal Response and Anamorphosis: the Case of Few-Layer Black Phosphorus,"Few-layer black phosphorus was recently rediscovered as a narrow-bandgap
+atomically thin semiconductor and has already attracted unprecedented attention
+due to its interesting properties. One feature of this material that sets it
+apart from other atomically thin crystals is its structural in-plane anisotropy
+which manifests in strongly anisotropic transport characteristics. However,
+traditional angle-resolved conductance measurements present a challenge for
+nanoscale systems such as black phosphorus, calling for new approaches in
+precision studies of transport anisotropy. Here we show that the nonlocal
+response, being exponentially sensitive to the anisotropy value, provides a
+powerful tool for determining the anisotropy. This is established by combining
+measurements of the orientation-dependent nonlocal resistance response with the
+analysis based on the anamorphosis relations. We demonstrate that the nonlocal
+response can differ by orders of magnitude for different crystallographic
+directions even when the anisotropy is at most order-one, allowing us to
+extract accurate anisotropy values.",1509.06537v1
+2015-11-15,Origin of the Resistivity Anisotropy in the Nematic Phase of FeSe,"The in-plane resistivity anisotropy is studied in strain-detwinned single
+crystals of FeSe. In contrast to other iron-based superconductors, FeSe does
+not develop long-range magnetic order below the nematic/structural transition
+at $T_{s}\approx$90~K. This allows for the disentanglement of the contributions
+to the resistivity anisotropy due to nematic and magnetic orders. Comparing
+direct transport and elastoresistivity measurements, we extract the intrinsic
+resistivity anisotropy of strain-free samples. The anisotropy peaks slightly
+below $T_{s}$ and decreases to nearly zero on cooling down to the
+superconducting transition. This behavior is consistent with a scenario in
+which the in-plane resistivity anisotropy in FeSe is dominated by inelastic
+scattering by anisotropic spin fluctuations.",1511.04757v1
+2016-01-09,Bubble and Skyrmion Crystals in Frustrated Magnets with Easy-Axis Anisotropy,"We clarify the conditions for the emergence of multiple-${\bf Q}$ structures
+out of lattice and easy-axis spin anisotropy in frustrated magnets. By
+considering magnets whose exchange interaction has multiple global minima in
+momentum space, we find that both types of anisotropy stabilize triple-${\bf
+Q}$ orderings. Moderate anisotropy leads to a magnetic field-induced skyrmion
+crystal, which evolves into a bubble crystal for increasing spatial or spin
+anisotropy. The bubble crystal exhibits a quasi-continuous (devil's staircase)
+temperature dependent ordering wave-vector, characteristic of the competition
+between frustrated exchange and strong easy-axis anisotropy.",1601.02064v2
+2016-01-11,Drag and Diffusion of Heavy Quarks in a hot and anisotropic QCD medium,"The propagation of heavy quarks (HQs) in a medium was quite often modeled by
+the Fokker-Plank (FP) equation. Since the transport coefficients, related to
+drag and diffusion processes are the main ingredients in the FP equation, the
+evolution of HQs is thus effectively controlled by them. At the initial stage
+of the relativistic heavy ion collisions, asymptotic weak-coupling causes the
+free-streaming motions of partons in the beam direction and the expansion in
+transverse directions are almost frozen, hence an anisotropy in the momentum
+space sets in. Since HQs are too produced in the same time therefore the study
+of the effect of momentum anisotropy on the drag and diffusion coefficients
+becomes advertently desirable. In this article we have thus studied the drag
+and diffusion of HQs in the anisotropic medium and found that the presence of
+the anisotropy reduces both drag and diffusion coefficients. In addition, the
+anisotropy introduces an angular dependence to both the drag and diffusion
+coefficients, as a result both coefficients get inflated when the partons are
+moving transverse to the direction of anisotropy than parallel to the direction
+of anisotropy.",1601.02341v1
+2016-03-01,Axisymmetric equilibria with pressure anisotropy and plasma flow,"A generalised Grad-Shafranov equation that governs the equilibrium of an
+axisymmetric toroidal plasma with anisotropic pressure and incompressible flow
+of arbitrary direction is derived. This equation includes six free surface
+functions and recovers known Grad-Shafranov-like equations in the literature as
+well as the usual static, isotropic one. The form of the generalised equation
+indicates that pressure anisotropy and flow act additively on equilibrium. In
+addition, two sets of analytical solutions, an extended Solovev one with a
+plasma reaching the separatrix and an extended Hernegger-Maschke one for a
+plasma surrounded by a fixed boundary possessing an X-point, are constructed,
+particularly in relevance to the ITER and NSTX tokamaks. Furthermore, the
+impacts both of pressure anisotropy and plasma flow on these equilibria are
+examined. It turns out that depending on the maximum value and the shape of an
+anisotropy function, the anisotropy can act either paramagnetically or
+diamagnetically. Also, in most of the cases considered both the anisotropy and
+the flow have stronger effects on NSTX equilibria than on ITER ones.",1603.00445v1
+2016-03-31,"Influence of the different strains components on the uniaxial magnetic anisotropy constants for (Ga,Mn)As bulk system: a First-Principles Study","We present a computational study of the magnetic anisotropy energy for a
+given concentration of the Mn ions in the GaAs host, in the framework of the
+density functional theory. We focus on the influence of a different kind of
+strains on the uniaxial magnetic anisotropy constants $K_1$ and $K_2$, which
+reflect the magnetic anisotropy energy out- and in- (001) plane, respectively.
+We have shown that the general trends for the applied biaxial strain on
+anisotropy constants are consistent with the experimental data. We have
+predicted the critical strains, for which the magnetization vector changes its
+direction. Our results have shown that it is not possible to modify
+considerably the uniaxial magnetic anisotropy constants, exposing (Ga,Mn)As to
+hydrostatic pressure of a magnitude reasonable from experimental point of view.",1603.09546v3
+2016-04-25,Higher order anisotropies in the Buda-Lund model: Disentangling flow and density field anisotropies,"The Buda-Lund hydro model describes an expanding ellipsoidal fireball, and
+fits the observed elliptic flow and oscillating HBT radii successfully. Due to
+fluctuations in energy depositions, the fireball shape however fluctuates on an
+event-by-event basis. The transverse plane asymmetry can be translated into a
+series of multipole anisotropy coefficients. These anisotropies then result in
+measurable momentum-space anisotropies, to be measured with respect to their
+respective symmetry planes. In this paper we detail an extension of the
+Buda-Lund model to multipole anisotropies and investigate the resulting flow
+coefficients and oscillations of HBT radii.",1604.07470v2
+2016-05-16,Polarization and dilepton anisotropy in pion-nucleon collisions,"Hadronic polarization and the related anisotropy of the dilepton angular
+distribution are studied for the reaction $\pi N \rightarrow Ne^+ e^-$. We
+employ consistent effective interactions for baryon resonances up to spin-5/2,
+where non-physical degrees of freedom are eliminated, to compute the anisotropy
+coefficients for isolated intermediate baryon resonances. It is shown that the
+spin and parity of the intermediate baryon resonance is reflected in the
+angular dependence of the anisotropy coefficient. We then compute the
+anisotropy coefficient including the $N(1520)$ and $N(1440)$ resonances, which
+are essential at the collision energy of the recent data obtained by the HADES
+collaboration on this reaction. We conclude that the anisotropy coefficient
+provides useful constraints for unravelling the resonance contributions to this
+process.",1605.04954v2
+2016-05-28,"Effects of $c/a$ Anisotropy and Local Crystal Structure on Superconductivity in $A\mathrm{Fe_{2}}(\mathrm{As}_{1-x}\mathrm{P}_{x}\mathrm{)_{2}}$ ($A$=Ba$_{1-y}$Sr$_y$, Sr$_{1-y}$Ca$_y$ and Eu)","We investigated the effects of $c/a$ anisotropy and local crystal structure
+on superconductivity (SC) in As/P solid solution systems,
+$A\mathrm{Fe_{2}}(\mathrm{As}_{1-x}\mathrm{P}_{x}\mathrm{)_{2}}$ ($A$122P) with
+various $A$ ions. With decreasing $A$ site atomic size from $A$=Ba to Eu, the
+structural anisotropy decreases, and the rate of decreasing with $x$ also
+increases. The rapid narrowing of the region of antiferromagnetic composition
+($x$) can be considered to be a result of this anisotropy change due mainly to
+the change in the Fermi surface (FS) nesting condition. By contrast, although
+the structural anisotropy systematically changes, the maximum $T_{\mathrm{c}}$
+values are almost the same in all $A$122P systems except for Eu122P. These
+results indicate that the modification of the FS topology via the structural
+anisotropy does not affect SC. However local structural parameters, such as
+pnictogen height, are crucial for $T_{\mathrm{c}}$.",1605.08914v1
+2016-05-30,"An integrated approach to doped thin films with strain tunable magnetic anisotropy: Powder synthesis, target preparation and pulsed laser deposition of Bi:YIG","We present a synthesis/processing method for fabricating ferrimagnetic
+insulator (Bi-doped yttrium iron garnet) thin films with tunable magnetic
+anisotropy. Since the desired magnetic properties rely on controllable
+thickness and successful doping, we pay attention to the entire
+synthesis/processing procedure (nanopowder synthesis, nanocrystalline target
+preparation and pulsed laser deposition (PLD)). Atomically flat films were
+deposited by PLD on (111)-orientated yttrium aluminum garnet. We show a
+significant enhancement of perpendicular anisotropy in the films, caused by
+strain-induced anisotropy. In addition, the perpendicular anisotropy is tunable
+by decreasing the film thickness and overwhelms the shape anisotropy at a
+critical thickness of 3.5 nm.",1605.09084v2
+2016-06-30,On anisotropy function in crystal growth simulations using Lattice Boltzmann equation,"In this paper, we present the ability of the Lattice Boltzmann (LB) equation,
+usually applied to simulate fluid flows, to simulate various shapes of
+crystals. Crystal growth is modeled with a phase-field model for a pure
+substance, numerically solved with a LB method in 2D and 3D. This study focuses
+on the anisotropy function that is responsible for the anisotropic surface
+tension between the solid phase and the liquid phase. The anisotropy function
+involves the unit normal vectors of the interface, defined by gradients of
+phase-field. Those gradients have to be consistent with the underlying lattice
+of the LB method in order to avoid unwanted effects of numerical anisotropy.
+Isotropy of the solution is obtained when the directional derivatives method,
+specific for each lattice, is applied for computing the gradient terms. With
+the central finite differences method, the phase-field does not match with its
+rotation and the solution is not any more isotropic. Next, the method is
+applied to simulate simultaneous growth of several crystals, each of them being
+defined by its own anisotropy function. Finally, various shapes of 3D crystals
+are simulated with standard and non standard anisotropy functions which favor
+growth in <100>-, <110>- and <111>-directions.",1606.09432v1
+2016-10-26,Effects of the Lorentz invariance violation in Coulomb interaction in nuclei and atoms,"Anisotropy in the speed of light that has been constrained by
+Michelson-Morley-type experiments also generates anisotropy in the Coulomb
+interactions. This anisotropy can manifest itself as an energy anisotropy in
+nuclear and atomic experiments. Here the experimental limits on Lorentz
+violation in 21Ne are used to improve the limits on the Lorentz symmetry in the
+photon sector, namely the anisotropy of the speed of light and the Coulomb
+interactions, by 7 orders of magnitude in comparison with previous experiments:
+the speed of light is isotropic to a part in E-28.",1610.08188v3
+2016-11-30,Temperature-dependent magnetic anisotropy from directional-dependent interactions,"Magnetic anisotropy of spin models with directional-dependent interactions in
+the high-temperature paramagnetic phase is theoretically studied. Using a high
+temperature expansion, we show that the Ising type directional-dependent
+interaction gives rise to magnetic anisotropy which depends on the temperature
+as $\propto T^{-5}$. This phenomenon arises from the anisotropic exchange
+interaction, and is distinct from the orbital effect, such as van Vleck
+susceptibility. It is shown that while the quadratic term in the magnetization
+favors to point the spins along the bond, the fourth order term in
+magnetization prefers to point spins to the perpendicular direction. The theory
+is applied to the Heisenberg-Kitaev model on the honeycomb lattice and a cubic
+lattice model that is potentially relevant to perovskite iridates. We show
+that, in these models, the anisotropic terms in quadratic order cancels out,
+and the leading order for the magnetic anisotropy arises from the fourth order
+contribution. The result shows that the anisotropy from the
+directional-dependent interaction gives rise to $\langle100\rangle$ magnetic
+anisotropy. These results are potentially relevant to heavy transition metal
+oxides such as iridates. Experimental observation of the magnitude of
+anisotropic interactions using magnetic torque measurement is also discussed.",1612.00057v1
+2017-02-13,Effective field theory of statistical anisotropies for primordial bispectrum and gravitational waves,"We present the effective field theory studies of primordial statistical
+anisotropies in models of anisotropic inflation. The general action in unitary
+gauge is presented to calculate the leading interactions between the gauge
+field fluctuations, the curvature perturbations and the tensor perturbations.
+The anisotropies in scalar power spectrum and bispectrum are calculated and the
+dependence of these anisotropies to EFT couplings are presented. In addition,
+we calculate the statistical anisotropy in tensor power spectrum and the
+scalar-tensor cross correlation. Our EFT approach incorporates anisotropies
+generated in models with non-trivial speed for the gauge field fluctuations and
+sound speed for scalar perturbations such as in DBI inflation.",1702.03744v1
+2017-03-02,Specific Heat and Effects of Uniaxial Anisotropy of a $p$-wave Pairing Interaction in a Strongly Interacting Ultracold Fermi Gas,"We investigate the specific heat $C_V$ at constant volume and effects of
+uniaxial anisotropy of a $p$-wave attractive interaction in the normal state of
+an ultracold Fermi gas. Within the framework of the strong-coupling theory
+developed by Nozi\`eres and Schmitt-Rink, we evaluate this thermodynamic
+quantity as a function of temperature, in the whole interaction regime. While
+the uniaxial anisotropy is not crucial for $C_V$ in the weak-coupling regime,
+$C_V$ is found to be sensitive to the uniaxial anisotropy in the
+strong-coupling regime. This originates from the population imbalance among
+$p_i$-wave molecules ($i=x,y,z$), indicating that the specific heat is a useful
+observable to see which kinds of $p$-wave molecules dominantly exist in the
+strong-coupling regime when the $p$-wave interaction has uniaxial anisotropy.
+Using this strong point, we classify the strong-coupling regime into some
+characteristic regions. Since a $p$-wave pairing interaction with uniaxial
+anisotropy has been discovered in a $^{40}$K Fermi gas, our results would be
+useful in considering strong-coupling properties of a $p$-wave interacting
+Fermi gas, when the interaction is uniaxially anisotropic.",1703.00585v1
+2017-04-12,On the origin of magnetic anisotropy in two dimensional CrI$_3$,"The observation of ferromagnetic order in a monolayer of CrI$_3$ has been
+recently reported, with a Curie temperature of 45 Kelvin and off-plane easy
+axis. Here we study the origin of magnetic anisotropy, a necessary ingredient
+to have magnetic order in two dimensions, combining two levels of modeling,
+density functional calculations and spin model Hamiltonians. We find two
+different contributions to the magnetic anisotropy of the material, both
+favoring off-plane magnetization and contributing to open a gap in the spin
+wave spectrum. First, ferromagnetic super-exchange across the $\simeq $ 90
+degree Cr-I-Cr bonds, are anisotropic, due to the spin orbit interaction of the
+ligand I atoms. Second, a much smaller contribution that comes from the single
+ion anisotropy of the $S=3/2$ Cr atom. Our results permit to establish the XXZ
+Hamiltonian, with a very small single ion anisotropy, as the adequate spin
+model for this system. Using spin wave theory we estimate the Curie temperature
+and we highlight the essential role played by the gap that magnetic anisotropy
+induces on the magnon spectrum.",1704.03849v4
+2017-05-26,Tuning of Fermi Contour Anisotropy in GaAs (001) 2D Holes via Strain,"We demonstrate tuning of the Fermi contour anisotropy of two-dimensional (2D)
+holes in a symmetric GaAs (001) quantum well via the application of in-plane
+strain. The ballistic transport of high-mobility hole carriers allows us to
+measure the Fermi wavevector of 2D holes via commensurability oscillations as a
+function of strain. Our results show that a small amount of in-plane strain, on
+the order of $10^{-4}$, can induce significant Fermi wavevector anisotropy as
+large as 3.3, equivalent to a mass anisotropy of 11 in a parabolic band. Our
+method to tune the anisotropy \textit{in situ} provides a platform to study the
+role of anisotropy on phenomena such as the fractional quantum Hall effect and
+composite fermions in interacting 2D systems.",1705.09430v1
+2017-06-26,Perpendicular magnetic anisotropy in insulating ferrimagnetic gadolinium iron garnet thin films,"We present experimental control of the magnetic anisotropy in a gadolinium
+iron garnet (GdIG) thin film from in-plane to perpendicular anisotropy by
+simply changing the sample temperature. The magnetic hysteresis loops obtained
+by SQUID magnetometry measurements unambiguously reveal a change of the
+magnetically easy axis from out-of-plane to in-plane depending on the sample
+temperature. Additionally, we confirm these findings by the use of temperature
+dependent broadband ferromagnetic resonance spectroscopy (FMR). In order to
+determine the effective magnetization, we utilize the intrinsic advantage of
+FMR spectroscopy which allows to determine the magnetic anisotropy independent
+of the paramagnetic substrate, while magnetometry determines the combined
+magnetic moment from film and substrate. This enables us to quantitatively
+evaluate the anisotropy and the smooth transition from in-plane to
+perpendicular magnetic anisotropy. Furthermore, we derive the temperature
+dependent $g$-factor and the Gilbert damping of the GdIG thin film.",1706.08488v1
+2017-08-23,Structural Transitions in Vortex Systems with Anisotropic Interactions,"We introduce a model of vortices in type-II superconductors with a four-fold
+anisotropy in the vortex-vortex interaction potential. Using numerical
+simulations we show that the vortex lattice undergoes structural transitions as
+the anisotropy is increased, with a triangular lattice at low anisotropy, a
+rhombic intermediate state, and a square lattice for high anisotropy. In some
+cases we observe a multi-$q$ state consisting of an Archimedean tiling that
+combines square and triangular local ordering. At very high anisotropy, domains
+of vortex chain states appear. We discuss how this model can be generalized to
+higher order anisotropy as well as its applicability to other particle-based
+systems with anisotropic particle-particle interactions.",1708.07116v1
+2017-09-06,Record High Magnetic Anisotropy in Chemically Engineered Iridium Dimer,"Exploring giant magnetic anisotropy in small magnetic nanostructures is of
+both fundamental interest and technological merit for information storage. To
+prevent spin flipping at room temperature due to thermal fluctuation, large
+magnetic anisotropy energy (MAE) over 50 meV in magnetic nanostructure is
+desired for practical applications. We chose one of the smallest magnetic
+nanostructures-Ir2 dimer, to investigate its magnetic properties and explore
+possible approach to engineer the magnetic anisotropy. Through systematic
+first-principles calculations, we found that the Ir2 dimer already possesses
+giant MAE of 77 meV. We proposed an effective way to enhance the MAE of the Ir2
+dimer to 223~294 meV by simply attaching a halogen atom at one end of the Ir-Ir
+bond. The underlying mechanism for the record high MAE is attributed to the
+modification of the energy diagram of the Ir2 dimer by the additional
+halogen-Ir bonding, which alters the spin-orbit coupling Hamiltonian and hence
+the magnetic anisotropy. Our strategy can be generalized to design other
+magnetic molecules or clusters with giant magnetic anisotropy.",1709.01878v1
+2017-11-30,On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials,"The scintillation anisotropy effect for proton recoil events has been
+investigated in five pure organic crystalline materials: anthracene,
+trans-stilbene, p-terphenyl, bibenzyl, and diphenylacetylene. These
+measurements include characterization of the scintillation response for one
+hemisphere of proton recoil directions in each crystal. In addition to standard
+measurements of the total light output and pulse shape at each angle, the
+prompt and delayed light anisotropies are analyzed, allowing for investigation
+of the singlet and triplet molecular excitation behaviors independently. This
+work provides new quantitative and qualitative observations that make progress
+toward understanding the physical mechanisms behind the scintillation
+anisotropy. These measurements show that the relationship between the prompt
+and delayed light anisotropies is correlated with crystal structure, as it
+changes between the pi-stacked crystal structure materials (anthracene and
+p-terphenyl) and the herringbone crystal structure materials (stilbene,
+bibenzyl, and diphenylacetylene). The observations are consistent with a model
+in which there are preferred directions of kinetic processes for the molecular
+excitations. These processes and the impact of their directional dependencies
+on the scintillation anisotropy are discussed.",1711.11188v2
+2018-03-12,Chiral skyrmions in an anisotropy gradient driven by spin-Hall effect,"A strategy to drive skyrmion motion by a combination of an anisotropy
+gradient and spin Hall effect has recently been demonstrated. Here, we study
+the fundamental properties of this type of motion by combining micromagnetic
+simulations and a generalized Thiele equation. We find that the anisotropy
+gradient drives the skyrmion mainly along the direction perpendicular to the
+gradient, due to the conservative part of the torque. There is some slower
+motion along the direction parallel to the anisotropy gradient due to damping
+torque. When an appropriate spin Hall torque is added, the skyrmion velocity in
+the direction of the anisotropy gradient can be enhanced. This motion gives
+rise to acceleration of the skyrmion as this moves to regions of varying
+anisotropy. This phenomenon should be taken into account in experiments for the
+correct evaluation of the skyrmion velocity. We employ a Thiele like formalism
+and derive expressions for the velocity and the acceleration of the skyrmion
+that match very well with micromagnetic simulation results.",1803.04160v1
+2018-03-14,Electronically Mediated Magnetic Anisotropy in Vibrating Magnetic Molecules,"We address the electronically induced anisotropy field acting on a spin
+moment comprised in a vibrating magnetic molecule located in the junction
+between ferromagnetic metals. Under weak coupling between the electrons and
+molecular vibrations, the nature of the anisotropy can be changed from favoring
+a high spin (easy axis) magnetic moment to a low spin (easy plane) by applying
+a temperature difference or a voltage bias across the junction. For unequal
+spin-polarizations in the ferromagnetic metals it is shown that the character
+of the anisotropy is essentially determined by the properties of the weaker
+ferromagnet. By increasing the temperature in this metal, or introducing a
+voltage bias, its influence can be suppressed such that the dominant
+contribution to the anisotropy is interchanged to the stronger ferromagnet.
+With increasing coupling strength between the molecular vibrations and the
+electrons, the nature of the anisotropy is locked into favoring easy plane
+magnetism.",1803.05480v1
+2018-03-28,Effective anisotropy due to the surface of magnetic nanoparticles,"Analytical solution has been found for the second-order effective anisotropy
+of magnetic nanoparticles of a cubic shape due to the surface anisotropy (SA)
+of the N\'eel type. Similarly to the spherical particles, for the simple cubic
+lattice the grand-diagonal directions $\left(\pm1,\pm1,\pm1\right)$ are favored
+by the effective cubic anisotropy but the effect is twice as strong. Uniaxial
+core anisotropy and applied magnetic field cause screening of perturbations
+from the surface at the distance of the domain-wall width and reduce the effect
+of SA near the energy minima. However, screening disappears near the uniaxial
+energy barrier, and the uniform barrier state of larger particles may become
+unstable. For these effects the analytical solution is obtained as well, and
+the limits of the additive formula with the uniaxial and effective cubic
+anisotropies for the particle are established. Thermally-activated
+magnetization-switching rates have been computed by the pulse-noise technique
+for the stochastic Landau-Lifshitz equation for a system of spins.",1803.10406v1
+2018-05-21,Searching for All-Scale Anisotropies in the Arrival Directions of Cosmic Rays above the Ankle,"The Pierre Auger Observatory has recently reported the detection of a dipole
+anisotropy in the arrival directions of cosmic rays above 8 EeV with a
+post-trial significance of more than 5.2$\sigma$. This observation has profound
+consequences for the distribution and composition of candidate sources of
+cosmic rays above the ankle (3-5 EeV). In this paper we search for the presence
+of anisotropies on all angular scales in public Auger data. The analysis
+follows a likelihood-based reconstruction method that automatically accounts
+for variations in the observatory's angular acceptance and background rate. Our
+best-fit dipole anisotropy in the equatorial plane has an amplitude of 5.3
+$\pm$ 1.3 percent and right ascension angle of 103 $\pm$ 15 degrees, consistent
+with the results of the Pierre Auger Collaboration. We do not find evidence for
+the presence of medium- or small-scale anisotropies. The method outlined in
+this paper is well-suited for the future analyses of cosmic ray anisotropies
+below the ankle, where cosmic ray detection in surface arrays is not fully
+efficient and dominated by systematic uncertainties.",1805.08220v2
+2018-07-13,Beaming electromagnetic (or heat-flux) instabilities from the interplay with the electron temperature anisotropies,"In space plasmas kinetic instabilities are driven by the beaming (drifting)
+components and/or the temperature anisotropy of charged particles. The
+heat-flux instabilities are known in the literature as electromagnetic modes
+destabilized by the electron beams (or strahls) aligned to the interplanetary
+magnetic field. A new kinetic approach is proposed here in order to provide a
+realistic characterization of heat-flux instabilities under the influence of
+electrons with temperature anisotropy. Numerical analysis is based on the
+kinetic Vlasov-Maxwell theory for two electron counter-streaming (core and
+beam) populations with temperature anisotropies, and stationary, isotropic
+protons. The main properties of electromagnetic heat-flux instabilities are
+found to be markedly changed by the temperature anisotropy of electron beam
+$A_b = T_\perp / T_\parallel \ne 1$, leading to stimulation of either the
+whistler branch if $A_b > 1$, or the firehose branch for $A_b<1$. For a high
+temperature anisotropy whistlers switch from heat-flux to a standard regime,
+when their instability is inhibited by the beam.",1807.05178v1
+2018-08-27,Dynamics of the antiferromagnetic skyrmion induced by a magnetic anisotropy gradient,"The dynamics of antiferromagnets is a current hot topic in condensed matter
+physics and spintronics. However, the dynamics of insulating antiferromagnets
+cannot be excited by an electric current, which is a method usually used to
+manipulate ferromagnetic metals. Here, we propose to use the voltage-controlled
+magnetic anisotropy gradient as an excitation source to manipulate insulating
+antiferromagnetic textures. We analytically and numerically study the dynamics
+of an antiferromagnetic skyrmion driven by a magnetic anisotropy gradient. Our
+analytical calculations demonstrate that such a magnetic anisotropy gradient
+can effectively drive an antiferromagnetic skyrmion towards the area of lower
+magnetic anisotropy. The micromagnetic simulations are in good agreement with
+our analytical solution. Furthermore, the magnetic anisotropy gradient induced
+velocity of an antiferromagnetic skyrmion is compared with that of a
+ferromagnetic skyrmion. Our results are useful for the understanding of
+antiferromagnetic skyrmion dynamics and may open a new way for the design of
+antiferromagnetic spintronic devices.",1808.08664v2
+2018-10-17,Testing isotropy in the Universe using photometric and spectroscopic data from the SDSS,"We analyze two volume limited galaxy samples from the SDSS photometric and
+spectroscopic data to test the isotropy in the local Universe. We use
+information entropy to quantify the global anisotropy in the galaxy
+distribution at different length scales and find that the galaxy distribution
+is highly anisotropic on small scales. The observed anisotropy diminishes with
+increasing length scales and nearly plateaus out beyond a length scale of 200
+Mpc/h in both the datasets. We compare these anisotropies with those predicted
+by the mock catalogues from the N-body simulations of the Lambda CDM model and
+find a fairly good agreement with the observations. We find a small residual
+anisotropy on large scales which decays in a way that is consistent with the
+linear perturbation theory. The slopes of the observed anisotropy converge to
+the slopes predicted by the linear theory beyond a length scale of ~ 200 Mpc/h
+indicating a transition to isotropy. We separately compare the anisotropies
+observed across the different parts of the sky and find no evidence for a
+preferred direction in the galaxy distribution.",1810.07410v2
+2019-01-02,Understanding the galactic cosmic ray dipole anisotropy with a nearby single source under the spatially-dependent propagation scenario,"Recently studies of the dipole anisotropy in the arrival directions of
+Galactic cosmic rays indicate that the TeV-PeV dipole anisotropy amplitude is
+not described by a simple power law, moreover a rapid phase change exists at an
+energy of $0.1\sim0.3$ PeV. In this work we argue that the dipole anisotropy
+amplitude and phase evolution with energies can be reproduced under the
+spatially-dependent propagation scenario with a nearby single source added. Our
+results indicate a nearby single source have significant influence to the
+cosmic ray gradient below $0.1\sim0.3$ PeV under the spatially-dependent
+propagation scenario, which leads the dipole anisotropy phase change at this
+energy region. The dipole anisotropy amplitude of the galactic cosmic rays can
+also be maintained at a lower level, which are consistent with observations by
+underground muons and air shower experiments.",1901.00249v1
+2019-02-08,Including off-diagonal anisotropies in anisotropic hydrodynamics,"In this paper we present a method for efficiently including the effects of
+off-diagonal local rest frame momentum anisotropies in leading-order
+anisotropic hydrodynamics. The method relies on diagonalization of the
+space-like block of the anisotropy tensor and allows one to reduce the
+necessary moments of the distribution function in the off-diagonal case to a
+linear combination of diagonal-anisotropy integrals. Once reduced to
+diagonal-anisotropy integrals, the results can be computed efficiently using
+techniques described previously in the literature. We present a general
+framework for how to accomplish this and provide examples for off-diagonal
+anisotropy moments entering into the energy-momentum tensor and viscous update
+equations which emerge when performing anisotropic pressure matching.",1902.03303v3
+2019-12-30,Magnetic resonance assessment of effective confinement anisotropy with orientationally-averaged single and double diffusion encoding,"Porous or biological materials comprise a multitude of micro-domains
+containing water. Diffusion-weighted magnetic resonance measurements are
+sensitive to the anisotropy of the thermal motion of such water. This
+anisotropy can be due to the domain shape, as well as the (lack of) dispersion
+in their orientations. Averaging over measurements that span all orientations
+is a trick to suppress the latter, thereby untangling it from the influence of
+the domains' anisotropy on the signal. Here, we consider domains whose
+anisotropy is modeled as being the result of a Hookean (spring) force, which
+has the advantage of having a Gaussian diffusion propagator while still
+retaining the fact of finite spatial range for the diffusing particles.
+Analytical expressions for the powder-averaged signal under this assumption are
+given for so-called single and double diffusion encoding schemes, which
+sensitize the MR signal to the diffusive displacement of particles in,
+respectively, one or two consecutive time intervals.",1912.12760v1
+2020-03-06,Anisotropy in Antiferromagnets,"Due to the advent of antiferromagnetic (AF) spintronics there is a burgeoning
+interest in AF materials for a wide range of potential and actual applications.
+Generally, AFs are characterized via the ordering at the Neel temperature (TN)
+but, to have a stable AF configuration, it is necessary that the material have
+a sufficient level of anisotropy so as to maintain the orientation of the given
+magnetic state fixed in one direction. Unlike the case for ferromagnets there
+is little established data on the anisotropy of AFs and in particular its
+origins and those factors which control it. In this paper these factors are
+reviewed in the light of recent and established experimental data.
+Additionally, there is no recognized technique for the first principle
+determination of the anisotropy of an AF which can only be found indirectly via
+the exchange bias phenomenon. This technique is reviewed and in particular the
+implications for the nature of the anisotropy that is measured and its
+distribution. Finally, a strategy is proposed that would allow for the
+development of AF materials with controlled anisotropy for future applications.",2003.03324v1
+2020-03-09,Interplay between chemical order and magnetic properties in L1$_0$ FeNi (tetrataenite): A First-Principles Study,"We use first-principles-based calculations to investigate the interplay
+between chemical order and the magnetic properties of $L1_0$ FeNi. In
+particular, we investigate how deviations from perfect chemical order affect
+the energy difference between the paramagnetic and ferromagnetic states as well
+as the important magneto-crystalline anisotropy energy. Our calculations
+demonstrate a strong effect of the magnetic order on the chemical
+order-disorder transition temperature, and conversely, a strong enhancement of
+the magnetic transition temperature by the chemical order. Most interestingly,
+our results indicate that the magnetic anisotropy does not decrease
+significantly as long as the deviations from perfect order are not too large.
+Moreover, we find that in certain cases a slight disorder can result in a
+higher anisotropy than for the fully ordered structure. We further analyze the
+correlation between the magneto-crystalline anisotropy and the orbital magnetic
+moment anisotropy, which allows to study the effect of the local chemical
+environment on both quantities, potentially enabling further optimization of
+the magneto-crystalline anisotropy with respect to chemical order and
+stoichiometric composition.",2003.04181v2
+2020-06-20,Two-fold symmetry of in-plane magnetoresistance anisotropy in the superconducting states of BiCh2-based LaO0.9F0.1BiSSe single crystal,"Recently, two-fold symmetric in-plane anisotropy of the superconducting
+properties have been observed in a single crystal of BiCh2-based (Ch: S, Se)
+layered superconductor LaO0.5F0.5BiSSe having a tetragonal
+(four-fold-symmetric) in-plane structure; the phenomena are very similar to
+those observed in nematic superconductors. To explore the origin of the
+two-fold symmetric anisotropy in the BiCh2-based system, we have investigated
+the electron-doping dependence on the anisotropy by examining the in-plane
+anisotropy of the magnetoresistance in the superconducting states for a single
+crystal of LaO0.9F0.1BiSSe under high magnetic fields up to 15 T. We observed a
+two-fold symmetry of in-plane anisotropy of magnetoresistance for
+LaO0.9F0.1BiSSe. The results obtained for LaO0.9F0.1BiSSe are quite similar to
+those observed for LaO0.5F0.5BiSSe, which has a higher electron doping
+concentration than LaO0.9F0.1BiSSe. Our present finding suggests that the
+emergence of the in-plane symmetry breaking in the superconducting state is
+robust to the carrier concentration in the series of LaO1-xFxBiSSe.",2006.11576v1
+2020-08-12,Velocity Centroids Anisotropy and the Signature of different MHD Modes in the Turbulent ISM,"Magnetic turbulence is anisotropic as the directions of motion are
+constrained by the magnetic field. Such anisotropy can be observed in velocity
+centroids obtained from spectroscopic observations. We use magnetohydrodynamics
+(MHD) simulations to produce synthetic spectroscopic observations
+(position-position-velocity data) and study the anisotropy in the structure
+function of velocity centroid maps. We decomposed the velocity in the
+simulations into Alfv\'en, slow and fast-modes and studied how each of them
+contribute to the observed anisotropy. We found that when the angle between the
+line of sight and the mean magnetic field is large the Alfv\'en-mode dominates
+the observed anisotropy, while for smaller angles the anisotropy is not large
+enough to be used to probe the magnetization of the media, and it is dominated
+by the slow-mode. Our results are in fair agreement with the theoretical
+predictions in Kandel et al.(2016,2017).",2008.05393v1
+2021-03-07,Bright correlated twin-beam generation and radiation shaping in high-gain parametric down-conversion with anisotropy,"Uniaxial anisotropy in nonlinear birefringent crystals limits the efficiency
+of nonlinear optical interactions and breaks the spatial symmetry of light
+generated in the parametric down-conversion (PDC) process. Therefore, this
+effect is usually undesirable and must be compensated for. However, high gain
+may be used to overcome the destructive role of anisotropy and instead to use
+it for the generation of bright two-mode correlated twin-beams. In this work,
+we provide a rigorous theoretical description of the spatial properties of
+bright squeezed light in the presence of strong anisotropy. We investigate a
+single-crystal and a two-crystal configuration and demonstrate the generation
+of bright correlated twin-beams in such systems at high gain due to anisotropy.
+We explore the mode structure of the generated light and show how anisotropy,
+together with crystal spacing, can be used for radiation shaping.",2103.04305v1
+2021-05-21,Stability of skyrmion crystal phase in antiferromagnetic triangular lattice with DMI and single-ion anisotropy,"We study a frustrated antiferromagnetic Heisenberg model on a triangular
+lattice with the Dzyaloshinskii-Moriya interaction (DMI) in the presence of an
+external magnetic field and a single-ion anisotropy. Phase diagrams in the
+temperature-field plane for both easy-axis and easy-plane anisotropy of a
+varying strength are constructed in the regimes of a moderate and strong DMI by
+parallel tempering Monte Carlo simulations. For the considered range of
+parameters the phase diagrams featuring up to four ordered phases are
+identified. A skyrmion lattice (SkX) phase is found to be stabilized within
+some temperature and field window for sufficiently large DMI and not too strong
+anisotropy. For the systems with moderate (larger) DMI, a small easy-plane
+(easy-axis) anisotropy is concluded to be beneficial by extending (shifting)
+the field window of the SkX appearance to lower values. The Metropolis dynamics
+is employed to probe the persistence of SkX upon quenching the field to zero or
+small finite values. The most favorable conditions for the skyrmions
+persistence are confirmed at low temperatures, small DMI and small easy-plane
+anisotropy values.",2105.10206v1
+2021-06-23,"Magnetic anisotropy in uranium monosulfide, probed by the magnetic torque measurements","We have studied the magnetic torque in uranium monosulfide (US) single
+crystals to explore the magnetic anisotropy in this material. Uranium
+monosulfide crystallizes in cubic, NaCl-type of crystal structure and exhibits
+the largest magneto-crystalline anisotropy observed in cubic systems. By
+performing detailed torque measurements we observe a strongly anisotropic
+behavior in the paramagnetic phase due to crystal defects and quadrupolar pair
+interactions. Our studies also confirm the presence of a large anisotropy in
+the ferromagnetic state of the US system with the <100>, <111>, and <110>
+directions being hard, easy, and intermediate axis, respectively. Furthermore,
+the anisotropy in the paramagnetic phase shows similar characteristics to the
+anisotropy observed in the ferromagnetic phase, as characterized by second and
+fourth rank susceptibility terms. The similarity of the anisotropic behaviors
+in paramagnetic and ferromagnetic phases is the consequence of strong
+magneto-elastic properties in this system, which possibly lead to the
+rhombohedral structural distortion, not only in the ferromagnetic phase but
+also in the paramagnetic phase (induced by applied magnetic fiield).",2106.12464v1
+2021-08-11,Enhancement of in-plane anisotropy in MoS2/CoFeB bilayers,"Transition metal dichalcogenides (TMD) possess novel properties which makes
+them potential candidates for various spintronic applications. Heterostructures
+of TMD with magnetic thin film have been extensively considered for
+spin-orbital torque, enhancement of perpendicular magnetic anisotropy etc.
+However, the effect of TMD on magnetic anisotropy in heterostructures of
+in-plane magnetization has not been studied so far. Further the effect of the
+TMD on the domain structure and magnetization reversal of the ferromagnetic
+system is another important aspect to be understood. In this context we study
+the effect of MoS2, a well-studied TMD material, on magnetic properties of
+CoFeB in MoS2/CoFeB heterostructures. The reference CoFeB film possess a weak
+in-plane anisotropy. However, when the CoFeB is deposited on MoS2 the in-plane
+anisotropy is enhanced as observed from magneto optic Kerr effect (MOKE)
+microscopy as well as ferromagnetic resonance (FMR). Magnetic domain structure
+and magnetization reversal have also been significantly modified for the
+MoS2/CoFeB bilayer as compared to the reference CoFeB layer. Frequency and
+angle dependent FMR measurement show that the magnetic anisotropy of CoFeB
+increases with increase in thickness of MoS2 in the MoS2/CoFeB
+heterostructures.",2108.05130v1
+2021-09-07,Testing the Early Universe with Anisotropies of the Gravitational Wave Background,"In this work we analyse in detail the possibility of using small and
+intermediate-scale gravitational wave anisotropies to constrain the
+inflationary particle content. First, we develop a phenomenological approach
+focusing on anisotropies generated by primordial tensor-tensor-scalar and
+purely gravitational non-Gaussianities. We highlight the quantities that play a
+key role in determining the detectability of the signal. To amplify the power
+of anisotropies as a probe of early universe physics, we consider
+cross-correlations with CMB temperature anisotropies. We assess the size of the
+signal from inflationary interactions against so-called induced anisotropies.
+In order to arrive at realistic estimates, we obtain the projected constraints
+on the non-linear primordial parameter $F_{\rm NL}$ for several upcoming
+gravitational wave probes in the presence of the astrophysical gravitational
+wave background. We further illustrate our findings by considering a concrete
+inflationary realisation and use it to underscore a few subtleties in the
+phenomenological analysis.",2109.03077v1
+2021-09-25,Phase transitions in rare-earth ferrimagnets with surface anisotropy near the magnetization compensation point,"We report of a theoretical model for calculating the H-T phase diagrams of a
+rare-earth ferrimagnet, taking into account anisotropies originated by both
+magnetization sublattices' and by the surface. The possibility of an exchange
+spring formation due to surface anisotropy is considered. This situation is
+realized in heterostructures containing a ferrimagnet and a heavy metal. We
+derive the stability lose lines of the collinear phase from the free energy of
+the two sublattice ferrimagnet. We numerical calculate the magnetic phase
+diagrams for the cases when the magnetic field applied along and perpendecular
+to the easy axis. We demonstrate that tricritical point down at the low field
+range due to surface anisotropy effect. Moreover, the line of the first order
+phase transition between angular and collinear phases reduces due to surface
+anisotropy. In the case when magnetic field is applied perpendicular to the
+easy axis we show the possibility of the first order phase transition between
+two collinear phases in contrast to the phase diagram without surface
+anisotropy.",2109.12377v2
+2021-10-26,The magnetic anisotropy of individually addressed spin states,"Controlling magnetic anisotropy is a key requirement for the fundamental
+understanding of molecular magnetism and is a prerequisite for numerous
+applications in magnetic storage, spintronics, and all-spin logic devices. In
+order to address the question of molecular magnetic anisotropy experimentally,
+we have synthesized single-crystals of a molecular spin system containing four
+antiferromagnetically coupled s = 5/2 manganese(II) ions. Using low-temperature
+cantilever magnetometry, we demonstrate the selective population of the S = 0,
+1, . . . , 10 spin states upon application of magnetic fields up to 33 T and
+map the magnetic anisotropy of each of these states. We observe a strong
+dependence of the shape and size of the magnetic anisotropy on the populated
+spin states, and, in particular, reveal an anisotropy reversal upon going from
+the lowest to the highest spin-state.",2110.13685v1
+2022-06-01,Scattering anisotropy in HgTe (013) quantum well,"We report on a detailed experimental study of the electron transport
+anisotropy in HgTe (013) quantum well of 22 nm width in the directions $[100]$
+and $[03\bar{1}]$ as the function of the electron density $n$. The anisotropy
+is absent at minimal electron density near the charge neutrality point. The
+anisotropy increases with the increase of n and reaches about 10% when the
+Fermi level is within the first subband H1. There is a sharp increase of the
+anisotropy (up to 60%) when the Fermi level reaches the second subband E2. We
+conclude that the first effect is due to the small intra-subband anisotropic
+interface roughness scattering, and the second one is due to the strongly
+anisotropic inter-subband roughness scattering, but the microscopical reason of
+such a strong change in the anisotropy remains unknown.",2206.00306v2
+2022-07-20,Modelling bubble collapse anisotropy in complex geometries,"A gas or vapor bubble collapsing in the vicinity of a rigid boundary
+displaces towards the boundary and produces a high-speed jet directed at the
+boundary. This behavior has been shown to be a function of the 'anisotropy' of
+the collapse, measured by a dimensionless representation of the Kelvin impulse
+known as the anisotropy parameter [Supponen et al., J. Fluid Mech. 802, 263-293
+(2016)]. However, characterisation of the anisotropy parameter in different
+geometries has been limited to simplified analytic solutions. In this work we
+develop an inexpensive numerical model, based on the Boundary Element Method,
+capable of predicting the anisotropy parameter for any rigid complex geometry.
+We experimentally explore a robust measure of bubble displacement, showing that
+the bubble displacement in a range of complex geometries behaves as a single
+function of the predicted anisotropy parameter values.",2207.09970v2
+2023-01-06,Interfacial magnetic anisotropy controlled spin pumping in Co60Fe20B20/Pt stack,"Controlled spin transport in magnetic stacks is required to realize pure spin
+current-driven logic and memory devices. The control over the generation and
+detection of the pure spin current is achieved by tuning the spin to charge
+conversion efficiency of the heavy metal interfacing with ferromagnets. Here,
+we demonstrate the direct tunability of spin angular momentum transfer and
+thereby spin pumping, in CoFeB/Pt stack, with interfacial magnetic anisotropy.
+The ultra-low thickness of CoFeB thin film tilts the magnetic easy axis from
+in-plane to out-of-plane due to surface anisotropy. The Ferromagnetic resonance
+measurements are performed to investigate the magnetic anisotropy and spin
+pumping in CoFeB/Pt stacks. We clearly observe tunable spin pumping effect in
+the CoFeB/Pt stacks with varying CoFeB thicknesses. The spin current density,
+with varying ferromagnetic layer thickness, is found to increase from 0.11 to
+0.24 MA/m2, with increasing in-plane anisotropy field. Such interfacial
+anisotropy-controlled generation of pure spin current can potentially lead to
+next-generation anisotropic spin current-controlled spintronic devices.",2301.02370v1
+2023-05-25,Origin of magnetic anisotropy in $La_{(1\-x)}Sr_{x}MnO_{3}$,"Here, we report the origin of magnetic anisotropy in Sr-doped infinite layer
+manganites $La_{(1\-x)}Sr_{x}MnO_{3}$ (0.125 \leq x \leq 0.400). Magnetic
+anisotropy is responsible for the large difference in the temperature
+dependence of field-cooled and zero-field-cooled magnetization. Translational
+symmetry breaking in the context of spins around the boundary between the
+ferromagnetic (FM) antiferromagnetic (AFM) region leads to FM-AFM interaction
+and results in magnetic anisotropy (exchange anisotropy). Here, we propose that
+FM-AFM interaction around the boundary between FM clusters or domains in the
+AFM background or between AFM clusters or domains in the ferromagnetic
+background is responsible for doping-dependent nonmonotonic behavior and the
+origin of magnetic anisotropy.",2305.16493v1
+2023-06-13,Is Anisotropy Inherent to Transformers?,"The representation degeneration problem is a phenomenon that is widely
+observed among self-supervised learning methods based on Transformers. In NLP,
+it takes the form of anisotropy, a singular property of hidden representations
+which makes them unexpectedly close to each other in terms of angular distance
+(cosine-similarity). Some recent works tend to show that anisotropy is a
+consequence of optimizing the cross-entropy loss on long-tailed distributions
+of tokens. We show in this paper that anisotropy can also be observed
+empirically in language models with specific objectives that should not suffer
+directly from the same consequences. We also show that the anisotropy problem
+extends to Transformers trained on other modalities. Our observations tend to
+demonstrate that anisotropy might actually be inherent to Transformers-based
+models.",2306.07656v1
+2023-07-27,Sensitivity of the IceCube-Gen2 Surface Array for Cosmic-Ray Anisotropy Studies,"The energy of the transition from Galactic to extra-galactic origin of cosmic
+rays is one of the major unresolved issues of cosmic-ray physics. However,
+strong constraints can be obtained from studying the anisotropy in the arrival
+directions of cosmic rays. The sensitivity to cosmic-ray anisotropy is, in
+particular, a matter of statistics. Recently, the cosmic ray anisotropy
+measurements in the TeV to PeV energy range were updated from IceCube using 11
+years of data. The IceCube-Gen2 surface array will cover an area about 8 times
+larger than the existing IceTop surface array with a corresponding increase in
+statistics and capability to investigate cosmic-ray anisotropy with higher
+sensitivity. In this contribution, we present details on the performed
+simulation studies and sensitivity to the cosmic-ray anisotropy signal for the
+IceCube-Gen2 surface array.",2307.14655v1
+2023-09-23,Anisotropies of Diffusive Ultra-high Energy Cosmic Rays in $f(R)$ Gravity Theory,"Understanding the anisotropy of ultra high-energy cosmic rays (UHECRs) is
+crucial for unraveling the origins and propagation mechanisms of these
+enigmatic particles. In this work, we studied the dipolar anisotropy of UHECRs
+in the diffusive regime by considering three cosmological models: the standard
+$\Lambda$CDM model, $f(R)$ gravity power-law model and the Starobinsky model.
+This work aims to see the role of the $f(R)$ gravity theory in understanding
+the anisotropy of UHECRs without condoning the standard cosmology. We found
+that the amplitude of the dipolar anisotropy is sensitive to these cosmological
+models, with the $f(R)$ power-law model predicting the largest amplitude, while
+the $\Lambda$CDM model predicting the smallest amplitude at most of the
+energies in the range considered. The predicted amplitude of the Starobinsky
+model lies within the range of the $\Lambda$CDM one. This work not only
+provides a way for exploration of UHECRs anisotropy within different
+cosmological contexts but also may pave the way for new avenues of research at
+the intersection of high-energy astrophysics.",2309.14361v1
+2023-11-15,Exotic magnetic anisotropy near digitized dimensional Mott boundary,"The magnetic anisotropy of low-dimensional Mott systems exhibits unexpected
+magnetotransport behavior useful for spin-based quantum electronics. Yet, the
+anisotropy of natural materials is inherently determined by the crystal
+structure, highly limiting its engineering. We demonstrate the magnetic
+anisotropy modulation near a digitized dimensional Mott boundary in artificial
+superlattices composed of a correlated magnetic monolayer SrRuO3 and
+nonmagnetic SrTiO3. The magnetic anisotropy is initially engineered by
+modulating the interlayer coupling strength between the magnetic monolayers.
+Interestingly, when the interlayer coupling strength is maximized, a nearly
+degenerate state is realized, in which the anisotropic magnetotransport is
+strongly influenced by both the thermal and magnetic energy scales. Our results
+offer a new digitized control for magnetic anisotropy in low-dimensional Mott
+systems, inspiring promising integration of Mottronics and spintronics.",2311.09322v1
+2023-12-22,Induced Cosmological Anisotropies and CMB Anomalies by a non-Abelian Gauge-Gravity Interaction,"We present a non-abelian cousin of the model presented in [1] which induces
+cosmological anisotropies on top of standard FLRW geometry. This is in some
+sense doing a cosmological mean field approximation, where the mean field
+cosmological model under consideration would be the standard FLRW, and the
+induced anisotropies are small perturbative corrections on top of it. Here we
+mostly focus on the non-abelian $SU(2)$ gauge fields coupled to the gravity to
+generate the anisotropies, which can be a viable model for the axion-like
+particle (ALP) dark sector. The induced anisotropies are consequences of the
+non-trivial back-reaction of the gauge fields on the gravity sector, and by a
+clever choice of the parametrization, one can generate the Bianchi model we
+have studied in this note. We also show that the anisotropies influence the
+Sachs-Wolfe effect and we discuss the implications.",2312.14513v2
+2024-01-22,Anisotropy Is Inherent to Self-Attention in Transformers,"The representation degeneration problem is a phenomenon that is widely
+observed among self-supervised learning methods based on Transformers. In NLP,
+it takes the form of anisotropy, a singular property of hidden representations
+which makes them unexpectedly close to each other in terms of angular distance
+(cosine-similarity). Some recent works tend to show that anisotropy is a
+consequence of optimizing the cross-entropy loss on long-tailed distributions
+of tokens. We show in this paper that anisotropy can also be observed
+empirically in language models with specific objectives that should not suffer
+directly from the same consequences. We also show that the anisotropy problem
+extends to Transformers trained on other modalities. Our observations suggest
+that anisotropy is actually inherent to Transformers-based models.",2401.12143v2
+2024-03-01,Cooperatively Modulating Magnetic Anisotropy and Colossal Magnetoresistance via Atomic-Scale Buffer Layers in Highly Strained La0.7Sr0.3MnO3 Films,"Simultaneous control of magnetic anisotropy and magnetoresistance, especially
+with atomic scale precision, remains a pivotal challenge for realizing advanced
+spintronic functionalities. Here we demonstrate cooperative continuous control
+over both magnetoresistance and magnetic anisotropy in highly strained
+La0.7Sr0.3MnO3 (LSMO) thin films. By inserting varying perovskite buffer
+layers, compressively strained LSMO films transition from a ferromagnetic
+insulator with out-of-plane magnetic anisotropy to a metallic state with
+in-plane anisotropy. Atomic-scale buffer layer insertion enables remarkably
+acute, precise control to sharply modulate this magnetic phase transformation.
+A gigantic 10,000% modulation of the colossal magnetoresistance (CMR) and an
+exceptionally sharp transition from out-of-plane to in-plane magnetic
+anisotropy are attained in just a few contiguous layers. These atomic-scale
+correlations among electronic, magnetic, and structural order parameters yield
+flexible multifunctional control promising for next-generation oxide
+spintronics.",2403.00361v1
+2008-09-01,Surface anisotropy broadening of the energy barrier distribution in magnetic nanoparticles,"The effect of surface anisotropy on the distribution of energy barriers in
+magnetic fine particles of nanometer size is discussed within the framework of
+the $T\ln(t/\tau_0)$ scaling approach. The comparison between the distributions
+of the anisotropy energy of the particle cores, calculated by multiplying the
+volume distribution by the core anisotropy, and of the total anisotropy energy,
+deduced by deriving the master curve of the magnetic relaxation with respect to
+the scaling variable $T\ln(t/\tau_0)$, enables the determination of the surface
+anisotropy as a function of the particle size. We show that the contribution of
+the particle surface to the total anisotropy energy can be well described by a
+size--independent value of the surface energy per unit area which permits the
+superimposition of the distributions corresponding to the particle core and
+effective anisotropy energies. The method is applied to a ferrofluid composed
+of non-interacting Fe$_{3-x}$O$_{4}$ particles of 4.9 nm in average size and
+$x$ about 0.07. Even though the size distribution is quite narrow in this
+system, a relatively small value of the effective surface anisotropy constant
+$K_{s}=2.9\times 10^{-2}$ erg cm$^{-2}$ gives rise to a dramatic broadening of
+the total energy distribution. The reliability of the average value of the
+effective anisotropy constant, deduced from magnetic relaxation data, is
+verified by comparing it to that obtained from the analysis of the shift of the
+ac susceptibility peaks as a function of the frequency.",0809.0203v2
+2016-03-03,Thermodynamic conditions during growth determine the magnetic anisotropy in epitaxial thin-films of La$_{0.7}$Sr$_{0.3}$MnO$_{3}$,"The suitability of a particular material for use in magnetic devices is
+determined by the process of magnetization reversal/relaxation, which in turn
+depends on the magnetic anisotropy. Therefore, designing new ways to control
+magnetic anisotropy in technologically important materials is highly desirable.
+Here we show that magnetic anisotropy of epitaxial thin-films of half-metallic
+ferromagnet La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) is determined by the proximity
+to thermodynamic equilibrium conditions during growth. We performed a series of
+X-ray diffraction and ferromagnetic resonance (FMR) experiments in two
+different sets of samples: the first corresponds to LSMO thin-films deposited
+under tensile strain on (001) SrTiO$_{3}$ by Pulsed Laser Deposition (PLD; far
+from thermodynamic equilibrium); the second were deposited by a slow Chemical
+Solution Deposition (CSD) method, under quasi-equilibrium conditions. Thin
+films prepared by PLD show a in-plane cubic anisotropy with an overimposed
+uniaxial term. A large anisotropy constant perpendicular to the film plane was
+also observed in these films. However, the uniaxial anisotropy is completely
+suppressed in the CSD films. The out of plane anisotropy is also reduced,
+resulting in a much stronger in plane cubic anisotropy in the chemically
+synthesized films. This change is due to a different rotation pattern of
+MnO$_{6}$ octahedra to accomodate epitaxial strain, which depends not only on
+the amount of tensile stress imposed by the STO substrate, but also on the
+growth conditions. Our results demonstrate that the nature and magnitude of the
+magnetic anisotropy in LSMO can be tuned by the thermodynamic parameters during
+thin-film deposition.",1603.01127v1
+2020-05-07,Correlations Between Fission Fragment and Neutron Anisotropies in Neutron-Induced Fission,"Several sources of angular anisotropy for fission fragments and prompt
+neutrons have been studied in neutron-induced fission reactions. These include
+kinematic recoils of the target from the incident neutron beam and the
+fragments from the emission of the prompt neutrons, preferential directions of
+the emission of the fission fragments with respect to the beam axis due to the
+population of particular transition states at the fission barrier, and
+forward-peaked angular distributions of pre-equilibrium neutrons which are
+emitted before the formation of a compound nucleus. In addition, there are
+several potential sources of angular anisotropies that are more difficult to
+disentangle: the angular distributions of prompt neutrons from fully
+accelerated fragments or from scission neutrons, and the emission of neutrons
+from fission fragments that are not fully accelerated. In this work, we study
+the effects of the first group of anisotropy sources, particularly exploring
+the correlations between the fission fragment anisotropy and the resulting
+neutron anisotropy. While kinematic effects were already accounted for in our
+Hauser-Feshbach Monte Carlo code, $\mathtt{CGMF}$, anisotropic angular
+distributions for the fission fragments and pre-equilibrium neutrons resulting
+from neutron-induced fission on $^{233,234,235,238}$U, $^{239,241}$Pu, and
+$^{237}$Np have been introduced for the first time. The effects of these
+sources of anisotropy are examined over a range of incident neutron energies,
+from thermal to 20 MeV, and compared to experimental data from the Chi-Nu
+liquid scintillator array. The anisotropy of the fission fragments is reflected
+in the anisotropy of the prompt neutrons, especially as the outgoing energy of
+the prompt neutrons increases, allowing for an extraction of the fission
+fragment anisotropy to be made from a measurement of the neutrons.",2005.03206v1
+1993-01-21,Minimal Microwave Anisotropy from Perturbations Induced at Late Times,"Aside from primordial gravitational instability of the cosmological fluid,
+various mechanisms have been proposed to generate large-scale structure at
+relatively late times, including, e.g., ``late-time'' cosmological phase
+transitions. In these scenarios, it is envisioned that the universe is nearly
+homogeneous at the time of last scattering and that perturbations grow rapidly
+sometime after the primordial plasma recombines. On this basis, it was
+suggested that large inhomogeneities could be generated while leaving
+relatively little imprint on the cosmic microwave background (MBR) anisotropy.
+In this paper, we calculate the minimal anisotropies possible in any
+``late-time'' scenario for structure formation, given the level of
+inhomogeneity observed at present. Since the growth of the inhomogeneity
+involves time-varying gravitational fields, these scenarios inevitably generate
+significant MBR anisotropy via the Sachs-Wolfe effect. Moreover, we show that
+the large-angle MBR anisotropy produced by the rapid post-recombination growth
+of inhomogeneity is generally greater than that produced by the same
+inhomogeneity grown via gravitational instability. In ``realistic'' scenarios
+one can decrease the anisotropy compared to models with primordial adiabatic
+fluctuations, but only on very small angular scales. The value of any
+particular measure of the anisotropy can be made small in late-time models, but
+only by making the time-dependence of the gravitational field sufficiently
+``pathological''.",9301011v1
+1996-01-26,On the microwave background anisotropy produced by big voids in open universes,"The Tolman-Bondi solution of the Einstein equations is used in order to model
+the time evolution of the void observed in Bo\""otes. The present density
+contrast of the central region ($\sim -0.75$) and its radius ($\sim 30h^{-1} \
+Mpc$) are fixed, while the density parameter of the Universe, the amplitude of
+the density contrast inside the void wall, the width of this wall and the
+distance from the void centre to the Local Group are appropriately varied. The
+microwave background anisotropy produced by Bo\""otes-like voids is estimated
+for a significant set of locations. All the voids are placed far from the last
+scattering surface. It is shown that the anisotropy generated by these voids
+strongly depends on the density parameter, the wall structure and the void
+location. The Doppler dipole and quadrupole are subtracted and the residual
+anisotropy is calculated. In the case of some isolated Bo\""otes-like voids
+placed at redshifts between 1 and 10 in an open universe with density parameter
+$\Omega_{0}=0.2$, the residual anisotropy appears to be a few times $10^{-6}$
+on scales of a few degrees. This anisotropy is about one order of magnitude
+greater than previous estimates corresponding to other cases. The anisotropy
+produced by a distribution of voids is qualitatively studied in the light of
+this result. Comparisons with previous estimates are discussed.",9601154v2
+2005-03-10,What will anisotropies in the clustering pattern in redshifted 21 cm maps tell us?,"The clustering pattern in high redshift HI maps is expected to be anisotropic
+due to two distinct reasons, the
+  Alcock-Paczynski effect and the peculiar velocities, both of which are
+sensitive to the cosmological parameters. The signal is also expected to be
+sensitive to the details of the HI distribution at the epoch when the radiation
+originated. We use simple models for the HI distribution at the epoch of
+reionizaation and the post-reionization era to investigate exactly what we hope
+to learn from future observations of the anisotropy pattern in HI maps. We find
+that such observations will probably tell us more about the HI distribution
+than about the background cosmological model. Assuming that reionization can be
+described by spherical, ionized bubbles all of the same size with their centers
+possibly being biased with respect to the dark matter, we find that the
+anisotropy pattern at small angles is expected to have a bump at the
+characteristic angular size of the individual bubbles whereas the large scale
+anisotropy pattern will reflect the size and the bias of the bubbles. The
+anisotropy also depends on the background cosmological parameters, but the
+dependence is much weaker. Under the assumption that the HI in the
+post-reionization era traces the dark matter with a possible bias, we find that
+changing the bias and changing the background cosmology has similar effects on
+the anisotropy pattern. Combining observations of the anisotropy with
+independent estimates of the bias, possibly from the bi-spectrum, may allow
+these observations to constrain cosmological parameters.",0503237v2
+1996-07-26,Detection of Anisotropies in the Gravitational-Wave Stochastic Background,"By correlating the signals from a pair of gravitational-wave detectors, one
+can undertake sensitive searches for a stochastic background of gravitational
+radiation. If the stochastic background is anisotropic, then this correlated
+signal varies harmonically with the earth's rotation. We calculate how the
+harmonics of this varying signal are related to the multipole moments which
+characterize the anisotropy, and give a formula for the signal-to-noise ratio
+of a given harmonic. The specific case of the two LIGO (Laser Interferometric
+Gravitational Observatory) detectors, which will begin operation around the
+year 2000, is analyzed in detail. We consider two possible examples of
+anisotropy. If the gravitational-wave stochastic background contains a dipole
+intensity anisotropy whose origin (like that of the Cosmic Background
+Radiation) is motion of our local system, then that anisotropy will be
+observable by the advanced LIGO detector (with 90% confidence in one year of
+observation) if \Omega_{gw} > 5.3 \times 10^{-8} h_{100}^{-2}. We also study
+the signal produced by stochastic sources distributed in the same way as the
+luminous matter in the galactic disk, and in the same way as the galactic halo.
+The anisotropy due to sources distributed as the galactic disk or as the
+galactic halo will be observable by the advanced LIGO detector (with 90%
+confidence in one year of observation) if \Omega_{gw} > 1.8 \times 10^{-10}
+h_{100}^{-2} or \Omega_{gw} > 6.7 \times 10^{-8} h_{100}^{-2}, respectively.",9607068v2
+2008-12-30,Anisotropy of the Optimally-Doped Iron Pnictide Superconductor Ba(Fe0.926Co0.074)2As2,"Anisotropies of electrical resistivity, upper critical field, London
+penetration depth and critical currents have been measured in single crystals
+of the optimally doped iron pnictide superconductor
+Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, $x$=0.074 and $T_c \sim$23 K. The normal state
+resistivity anisotropy was obtained by employing both the Montgomery technique
+and direct measurements on samples cut along principal crystallographic
+directions. The ratio $\gamma_{\rho} = \rho_c /\rho_a$ is about 4$\pm$1 just
+above $T_c$ and becomes half of that at room temperature. The anisotropy of the
+upper critical field, $\gamma_{H} = H_{c2,ab} /H_{c2,c} $, as determined from
+specific heat measurements close to $T_c$, is in the range of 2.1 to 2.6,
+depending on the criterion used. A comparable low anisotropy of the London
+penetration depth, $\gamma_{\lambda}=\lambda_{c}/\lambda_{ab}$, was recorded
+from TDR measurements and found to persist deep into the superconducting state.
+An anisotropy of comparable magnitude was also found in the critical currents,
+$\gamma_j=j_{c,ab}/j_{c,c}$, as determined from both direct transport
+measurements ($\sim$1.5) and from the analysis of the magnetization data
+($\sim$3). Overall, our results show that iron pnictide superconductors
+manifest anisotropies consistent with essentially three-dimensional
+intermetallic compound and bear little resemblance to cuprates.",0812.4991v1
+2011-02-06,Experimental study of the influence of anisotropy on the inertial scales of turbulence,"We ask whether the scaling exponents or the Kolmogorov constants depend on
+the anisotropy of the velocity fluctuations in a turbulent flow with no shear.
+According to our experiment, the answer is no for the Eulerian second-order
+transverse velocity structure function. The experiment consisted of 32
+loudspeaker-driven jets pointed toward the centre of a spherical chamber. We
+generated anisotropy by controlling the strengths of the jets. We found that
+the form of the anisotropy of the velocity fluctuations was the same as that in
+the strength of the jets. We then varied the anisotropy, as measured by the
+ratio of axial to radial root-mean-square (RMS) velocity fluctuations, between
+0.6 and 2.3. The Reynolds number was approximately constant at around
+$R_\lambda$ = 481. In a central volume with a radius of 50 mm, the turbulence
+was approximately homogeneous, axisymmetric, and had no shear and no mean flow.
+We observed that the scaling exponent of the structure function was $0.70 \pm
+0.03$, independent of the anisotropy and regardless of the direction in which
+we measured it. The Kolmogorov constant, $C_2$, was also independent of
+direction and anisotropy to within the experimental error of 4%.",1102.1197v2
+2011-03-01,Magnetothermal instabilities in magnetized anisotropic plasmas,"Using the transport equations for an ideal anisotropic collisionless plasma
+derived from the Vlasov equation by the 16-moment method, we analyse the
+influence of pressure anisotropy exhibited by collisionless magnetized plasmas
+on the magnetothermal (MTI) and heat-flux-driven buoyancy (HBI) instabilities.
+We calculate the dispersion relation and the growth rates for these
+instabilities in the presence of a background heat flux and for configurations
+with static pressure anisotropy, finding that when the frequency at which heat
+conduction acts is much larger than any other frequency in the system (i.e.
+weak magnetic field) the pressure anisotropy has no effect on the MTI/HBI,
+provided the degree of anisotropy is small. In contrast, when this ordering of
+timescales does not apply the instability criteria depend on pressure
+anisotropy. Specifically, the growth time of the instabilities in the
+anisotropic case can be almost one order of magnitude smaller than its
+isotropic counterpart. We conclude that in plasmas where pressure anisotropy is
+present the MTI/HBI are modified. However, in environments with low magnetic
+fields and small anisotropy such as the ICM the results obtained from the
+16-moment equations under the approximations considered are similar to those
+obtained from ideal MHD.",1103.0310v3
+2012-02-23,Joint anisotropy and source count constraints on the contribution of blazars to the diffuse gamma-ray background,"We place new constraints on the contribution of blazars to the large-scale
+isotropic gamma-ray background (IGRB) by jointly analyzing the measured source
+count distribution (logN-logS) of blazars and the measured intensity and
+anisotropy of the IGRB. We find that these measurements point to a consistent
+scenario in which unresolved blazars make less than 20% of the IGRB intensity
+at 1-10 GeV while accounting for the majority of the measured anisotropy in
+that energy band. These results indicate that the remaining fraction of the
+IGRB intensity is made by a component with a low level of intrinsic anisotropy.
+We determine upper limits on the anisotropy from non-blazar sources, adopting
+the best-fit parameters of the measured source count distribution to calculate
+the unresolved blazar anisotropy. In addition, we show that the anisotropy
+measurement excludes some recently proposed models of the unresolved blazar
+population.",1202.5309v2
+2012-10-17,Measurements of electron anisotropy in solar flares using albedo with RHESSI X-ray data,"The angular distribution of electrons accelerated in solar flares is a key
+parameter in the understanding of the acceleration and propagation mechanisms
+that occur there. However, the anisotropy of energetic electrons is still a
+poorly known quantity, with observational studies producing evidence for an
+isotropic distribution and theoretical models mainly considering the strongly
+beamed case. We use the effect of photospheric albedo to infer the pitch angle
+distribution of X-ray emitting electrons using Hard X-ray data from RHESSI. A
+bi-directional approximation is applied and a regularized inversion is
+performed for eight large flare events to deduce the electron spectra in both
+downward (towards the photosphere) and upward (away from the photosphere)
+directions. The electron spectra and the electron anisotropy ratios are
+calculated for broad energy range from about 10 and up to ~ 300 keV near the
+peak of the flares. The variation of electron anisotropy over short periods of
+time intervals lasting 4, 8 and 16 seconds near the impulsive peak has been
+examined. The results show little evidence for strong anisotropy and the mean
+electron flux spectra are consistent with the isotropic electron distribution.
+The 3-sigma level uncertainties, although energy and event dependent, are found
+to suggest that anisotropic distribution with anisotropy larger than ~ 3 are
+not consistent with the hard X-ray data. At energies above 150-200 keV, the
+uncertainties are larger and thus the possible electron anisotropies could be
+larger.",1210.4757v1
+2013-04-04,Reconnection and electron temperature anisotropy in sub-proton scale plasma turbulence,"Turbulent behavior at sub-proton scales in magnetized plasmas is important
+for a full understanding of the energetics of astrophysical flows such as the
+solar wind. We study the formation of electron temperature anisotropy due to
+reconnection in the turbulent decay of sub-proton scale fluctuations using two
+dimensional, particle-in-cell (PIC) plasma simulations with realistic
+electron-proton mass ratio and a guide field out of the simulation plane. A
+fluctuation power spectrum with approximately power law form is created down to
+scales of order the electron gyroradius. In the dynamic magnetic field
+topology, which gradually relaxes in complexity, we identify the signatures of
+collisionless reconnection at sites of X-point field geometry. The reconnection
+sites are generally associated with regions of strong parallel electron
+temperature anisotropy. The evolving topology of magnetic field lines connected
+to a reconnection site allows spatial mixing of electrons accelerated at
+multiple, spatially separated reconnection regions. This leads to the formation
+of multi-peaked velocity distribution functions with a strong parallel
+temperature anisotropy. In a three-dimensional system, supporting the
+appropriate wave vectors, the multi-peaked distribution functions would be
+expected to be unstable to kinetic instabilities, contributing to dissipation.
+The proposed mechanism of anisotropy formation is also relevant to space and
+astrophysical systems where the evolution of the plasma is constrained by
+linear temperature anisotropy instability thresholds. The presence of
+reconnection sites leads to electron energy gain, nonlocal velocity space
+mixing and the formation of strong temperature anisotropy; this is evidence of
+an important role for reconnection in the dissipation of turbulent
+fluctuations.",1304.1444v2
+2013-09-12,Origin and spectroscopic determination of trigonal anisotropy in a heteronuclear single-molecule magnet,"W-band ({\nu} ca. 94 GHz) electron paramagnetic resonance (EPR) spectroscopy
+was used for a single-crystal study of a star-shaped Fe3Cr single-molecule
+magnet (SMM) with crystallographically imposed trigonal symmetry. The high
+resolution and sensitivity accessible with W-band EPR allowed us to determine
+accurately the axial zero-field splitting terms for the ground (S =6) and first
+two excited states (S =5 and S =4). Furthermore, spectra recorded by applying
+the magnetic field perpendicular to the trigonal axis showed a pi/6 angular
+modulation. This behavior is a signature of the presence of trigonal transverse
+magnetic anisotropy terms whose values had not been spectroscopically
+determined in any SMM prior to this work. Such in-plane anisotropy could only
+be justified by dropping the so-called 'giant spin approach' and by considering
+a complete multispin approach. From a detailed analysis of experimental data
+with the two models, it emerged that the observed trigonal anisotropy directly
+reflects the structural features of the cluster, i.e., the relative orientation
+of single-ion anisotropy tensors and the angular modulation of single-ion
+anisotropy components in the hard plane of the cluster. Finally, since
+high-order transverse anisotropy is pivotal in determining the spin dynamics in
+the quantum tunneling regime, we have compared the angular dependence of the
+tunnel splitting predicted by the two models upon application of a transverse
+field (Berry-phase interference).",1309.3098v1
+2013-12-31,Orthogonal invariant sets of the diffusion tensor and the development of a curvilinear set suitable for low-anisotropy tissues,"We develop a curvilinear invariant set of the diffusion tensor which may be
+applied to Diffusion Tensor Imaging measurements on tissues and porous media.
+This new set is an alternative to the more common invariants such as fractional
+anisotropy and the diffusion mode. The alternative invariant set possesses a
+different structure to the other known invariant sets; the second and third
+members of the curvilinear set measure the degree of orthotropy and
+oblateness/prolateness, respectively. The proposed advantage of these
+invariants is that they may work well in situations of low diffusion anisotropy
+and isotropy, as is often observed in tissues such as cartilage.
+  We also explore the other orthogonal invariant sets in terms of their
+geometry in relation to eigenvalue space; a cylindrical set, a spherical set
+(including fractional anisotropy and the mode), and a log-Euclidean set. These
+three sets have a common structure. The first invariant measures the magnitude
+of the diffusion, the second and third invariants capture aspects of the
+anisotropy; the magnitude of the anisotropy and the shape of the diffusion
+ellipsoid (the manner in which the anisotropy is realised). We also show a
+simple method to prove the orthogonality of the invariants within a set.",1401.0165v1
+2014-01-19,Electronic nematic phase transition in the presence of anisotropy,"We study the phase diagram of electronic nematic instability in the presence
+of xy anisotropy. While a second order transition cannot occur in this case,
+mean-field theory predicts that a first order transition occurs near van Hove
+filling and its phase boundary forms a wing structure, which we term a
+Griffiths wing, referring to his original work of He3-He4 mixtures. When
+crossing the wing, the anisotropy of the electronic system exhibits a
+discontinuous change, leading to a meta-nematic transition, i.e., the analog to
+a meta-magnetic transition in a magnetic system. The upper edge of the wing
+corresponds to a critical end line, which shows a non-monotonic temperature
+dependence as a function of the external anisotropy and vanishes at a quantum
+critical end point for a strong anisotropy. The mean-field phase diagram is,
+however, very sensitive to fluctuations of the nematic order parameter,
+yielding a topologically different phase diagram. The Griffiths wing is broken
+into two pieces. A tiny wing appears close to zero anisotropy and the other is
+realized for a strong anisotropy. Consequently three quantum critical end
+points are realized. We discuss that these results can be related to various
+materials including a cold atom system.",1401.4628v3
+2014-05-06,Giant dielectric anisotropy via homogenization,"A random mixture of two isotropic dielectric materials, one composed of
+oriented spheroidal particles of relative permittivity $\epsilon_a$ and the
+other composed of oriented spheroidal particles of relative permittivity
+$\epsilon_b$, was considered in the long wavelength regime. The permittivity
+dyadic of the resulting homogenized composite material (HCM) was estimated
+using the Bruggeman homogenization formalism. The HCM was an orthorhombic
+biaxial material if the symmetry axes of the two populations of spheroids were
+mutually perpendicular and a uniaxial material if these two axes were mutually
+aligned. The degree of anisotropy of the HCM, as gauged by the ratio of the
+eigenvalues of the HCM's permittivity dyadic, increased as the shape of the
+constituent particles became more eccentric. The greatest degrees of HCM
+anisotropy were achieved for the limiting cases wherein the constituent
+particles were shaped as needles or discs. In these instances explicit formulas
+for the HCM anisotropy were derived from the dyadic Bruggeman equation. Using
+these formulas it was found that the degrees of HCM anisotropy are proportional
+to $\sqrt{\epsilon_b}$ or $\epsilon_b$, at fixed values of volume fraction and
+$\epsilon_a$, for $\epsilon_b > \epsilon_a$. Thus, in principle, there is no
+limit to degree of anisotropy that may be attained via homogenization. In
+practice, the degree of anisotropy would be limited by the available value of
+$\epsilon_b$ (and/or $\epsilon_a$).",1405.1198v1
+2014-07-11,Fermi-LAT gamma-ray anisotropy and intensity explained by unresolved Radio-Loud Active Galactic Nuclei,"Radio-loud active galactic nuclei (AGN) are expected to contribute
+substantially to both the intensity and anisotropy of the isotropic gamma-ray
+background (IGRB). In turn, the measured properties of the IGRB can be used to
+constrain the characteristics of proposed contributing source classes. We
+consider individual subclasses of radio-loud AGN, including low-,
+intermediate-, and high-synchrotron-peaked BL Lacertae objects, flat-spectrum
+radio quasars, and misaligned AGN. Using updated models of the gamma-ray
+luminosity functions of these populations, we evaluate the energy-dependent
+contribution of each source class to the intensity and anisotropy of the IGRB.
+We find that collectively radio-loud AGN can account for the entirety of the
+IGRB intensity and anisotropy as measured by the Fermi Large Area Telescope
+(LAT). Misaligned AGN provide the bulk of the measured intensity but a
+negligible contribution to the anisotropy, while high-synchrotron-peaked BL
+Lacertae objects provide the dominant contribution to the anisotropy. In
+anticipation of upcoming measurements with the Fermi-LAT and the forthcoming
+Cherenkov Telescope Array, we predict the anisotropy in the broader energy
+range that will be accessible to future observations.",1407.3275v2
+2014-08-21,Measuring the Alfvenic Nature of the Interstellar Medium: Velocity Anisotropy Revisited,"The dynamics of the interstellar medium (ISM) are strongly affected by
+turbulence, which shows increased anisotropy in the presence of a magnetic
+field. We expand upon the Esquivel & Lazarian method to estimate the Alfven
+Mach number using the structure function anisotropy in velocity centroid data
+from position-position-velocity maps. We utilize 3D magnetohydrodynamic (MHD)
+simulations of fully developed turbulence, with a large range of sonic and
+Alfvenic Mach numbers, to produce synthetic observations of velocity centroids
+with observational characteristics such as thermal broadening, cloud
+boundaries, noise, and radiative transfer effects of carbon monoxide. In
+addition, we investigate how the resulting anisotropy-Alfven Mach number
+dependency found in Esquivel & Lazarian (2011) might change when taking the
+second moment of the position-position-velocity cube or when using different
+expressions to calculate the velocity centroids. We find that the degree of
+anisotropy is related primarily to the magnetic field strength (i.e. Alfven
+Mach number) and the line-of-sight orientation, with a secondary effect on
+sonic Mach number. If the line-of-sight is parallel to up to ~45 deg off of the
+mean field direction, the velocity centroid anisotropy is not prominent enough
+to distinguish different Alfvenic regimes. The observed anisotropy is not
+strongly affected by including radiative transfer, although future studies
+should include additional tests for opacity effects. These results open up the
+possibility of studying the magnetic nature of the ISM using statistical
+methods in addition to existing observational techniques.",1408.4858v1
+2015-03-02,Anisotropy and Strong-Coupling Effects on the Collective Mode Spectrum of Chiral Superconductors: Application to Sr$_2$RuO$_4$,"Recent theories of Sr$_2$RuO$_4$ based on the interplay of strong
+interactions, spin-orbit coupling and multi-band anisotropy predict chiral or
+helical ground states with strong anisotropy of the pairing states, with deep
+minima in the excitation gap, as well as strong phase anisotropy for the chiral
+ground state. We develop time-dependent mean field theory to calculate the
+Bosonic spectrum for the class of 2D chiral superconductors spanning $^3$He-A
+to chiral superconductors with strong anisotropy. Chiral superconductors
+support a pair of massive Bosonic excitations of the time-reversed pairs
+labeled by their parity under charge conjugation. These modes are degenerate
+for 2D $^3$He-A. Crystal field anisotropy lifts the degeneracy. Strong
+anisotropy also leads to low-lying Fermions, and thus to channels for the decay
+of the Bosonic modes. Selection rules and phase space considerations lead to
+large asymmetries in the lifetimes and hybridization of the Bosonic modes with
+the continuum of un-bound Fermion pairs. We also highlight results for the
+excitation of the Bosonic modes by microwave radiation that provide clear
+signatures of the Bosonic modes of an anisotropic chiral ground state.",1503.00624v2
+2015-06-02,Clustering Fossil from Primordial Gravitational Waves in Anisotropic Inflation,"Inflationary models can correlate small-scale density perturbations with the
+long-wavelength gravitational waves (GW) in the form of the
+Tensor-Scalar-Scalar (TSS) bispectrum. This correlation affects the
+mass-distribution in the Universe and leads to the off-diagonal correlations of
+the density field modes in the form of the quadrupole anisotropy.
+Interestingly, this effect survives even after the tensor mode decays when it
+re-enters the horizon, known as the fossil effect. As a result, the
+off-diagonal correlation function between different Fourier modes of the
+density fluctuations can be thought as a way to probe the large-scale GW and
+the mechanism of inflation behind the fossil effect. Models of single field
+slow roll inflation generically predict a very small quadrupole anisotropy in
+TSS while in models of multiple fields inflation this effect can be observable.
+Therefore this large scale quadrupole anisotropy can be thought as a
+spectroscopy for different inflationary models. In addition, in models of
+anisotropic inflation there exists quadrupole anisotropy in curvature
+perturbation power spectrum. Here we consider TSS in models of anisotropic
+inflation and show that the shape of quadrupole anisotropy is different than in
+single field models. In addition in these models the quadrupole anisotropy is
+projected into the preferred direction and its amplitude is proportional to
+$g_* N_e$ where $N_e$ is the number of e-folds and $g_*$ is the amplitude of
+quadrupole anisotropy in curvature perturbation power spectrum. We use this
+correlation function to estimate the large scale GW as well as the preferred
+direction and discuss the detectability of the signal in the galaxy surveys
+like Euclid and 21 cm surveys.",1506.00958v1
+2015-06-17,"Consequences of viscous anisotropy in a deforming, two-phase aggregate. Why is porosity-band angle lowered by viscous anisotropy?","In laboratory experiments that impose shear deformation on partially molten
+aggregates of initially uniform porosity, melt segregates into high-porosity
+sheets (bands in cross-section). The bands emerge at 15-20 degrees to the shear
+plane. A model of viscous anisotropy can explain these low angles whereas
+previous, simpler models have failed to do so. The anisotropic model is
+complex, however, and the reason that it produces low-angle bands has not been
+understood. Here we show that there are two mechanisms: (i) suppression of the
+well-known tensile instability, and (ii) creation of a new, shear-driven
+instability. We elucidate these mechanisms using linearised stability analysis
+in a coordinate system that is aligned with the perturbations. We consider the
+general case of anisotropy that varies dynamically with deviatoric stress, but
+approach it by first considering uniform anisotropy that is imposed a priori
+and showing the difference between static and dynamic cases. We extend the
+model of viscous anisotropy to include a strengthening in the direction of
+maximum compressive stress. Our results support the hypothesis that viscous
+anisotropy is the cause of low band-angles in experiments.",1506.05286v2
+2015-08-23,Fire Hose instability driven by alpha particle temperature anisotropy,"We investigate properties of a solar wind-like plasma including a secondary
+alpha particle population exhibiting a parallel temperature anisotropy with
+respect to the background magnetic field, using linear and quasi-linear
+predictions and by means of one-dimensional hybrid simulations. We show that
+anisotropic alpha particles can drive a parallel fire hose instability
+analogous to that generated by protons, but that, remarkably, the instability
+can be triggered also when the parallel plasma beta of alpha particles is below
+unity. The wave activity generated by the alpha anisotropy affects the
+evolution of the more abundant protons, leading to their anisotropic heating.
+When both ion species have sufficient parallel anisotropies both of them can
+drive the instability, and we observe generation of two distinct peaks in the
+spectra of the fluctuations, with longer wavelengths associated to alphas and
+shorter ones to protons. If a non-zero relative drift is present, the unstable
+modes propagate preferentially in the direction of the drift associated with
+the unstable species. The generated waves scatter particles and reduce their
+temperature anisotropy to marginally stable state, and, moreover, they
+significantly reduce the relative drift between the two ion populations. The
+coexistence of modes excited by both species leads to saturation of the plasma
+in distinct regions of the beta/anisotropy parameter space for protons and
+alpha particles, in good agreement with in situ solar wind observations. Our
+results confirm that fire hose instabilities are likely at work in the solar
+wind and limit the anisotropy of different ion species in the plasma.",1508.05638v1
+2015-08-26,Anatomy and giant enhancement of the perpendicular magnetic anisotropy of cobalt-graphene heterostructures,"We report strongly enhanced perpendicular magnetic anisotropy (PMA) of Co
+films by graphene coating from both first-principles and experiments. Our
+calculations show that graphene can dramatically boost the surface anisotropy
+of Co films up to twice the value of its pristine counterpart and can extend
+the out-of-plane effective anisotropy up to unprecedented thickness of 25~\AA.
+These findings are supported by our experiments on graphene coating on Co films
+grown on Ir substrate. Furthermore, we report layer-resolved and
+orbital-hybridization-resolved anisotropy analysis which help understanding the
+physical mechanisms of PMA and more practically can help design structures with
+giant PMA. As an example, we propose super-exchange stabilized Co-graphene
+heterostructures with a robust out-of-plane constant effective PMA and linearly
+increasing interfacial anisotropy as a function of film thickness. These
+findings point towards possibilities to engineer graphene/ferromagnetic metal
+heterostructures with giant magnetic anisotropy more than 20 times larger
+compared to conventional multilayers, which constitutes a hallmark for future
+graphene and traditional spintronic technologies.",1508.06681v1
+2015-11-10,Primordial Statistical Anisotropies: The Effective Field Theory Approach,"In this work we present the effective field theory of primordial statistical
+anisotropies generated during anisotropic inflation involving a background
+$U(1)$ gauge field. Besides the usual Goldstone boson associated with the
+breaking of time diffeomorphism we have two additional Goldstone bosons
+associated with the breaking of spatial diffeomorphisms. We further identify
+these two new Goldstone bosons with the expected two transverse degrees of the
+$U(1)$ gauge field fluctuations. Upon defining the appropriate unitary gauge,
+we present the most general quadratic action which respects the remnant
+symmetry in the unitary gauge. The interactions between various Goldstone
+bosons leads to statistical anisotropy in curvature perturbation power
+spectrum. Calculating the general results for power spectrum anisotropy, we
+recover the previously known results in specific models of anisotropic
+inflation. In addition, we present novel results for statistical anisotropy in
+models with non-trivial sound speed for inflaton fluctuations. Also we identify
+the interaction which leads to birefringence-like effects in anisotropic power
+spectrum in which the speed of gauge field fluctuations depends on the
+direction of the mode propagation and the two polarization of gauge field
+fluctuations contribute differently in statistical anisotropy. As another
+interesting application, our EFT approach naturally captures interactions
+generating parity violating statistical anisotropies.",1511.03218v1
+2015-12-04,Measures of Three-Dimensional Anisotropy and Intermittency in Strong Alfvénic Turbulence,"We measure the local anisotropy of numerically simulated strong Alfv\'enic
+turbulence with respect to two local, physically relevant directions: along the
+local mean magnetic field and along the local direction of one of the
+fluctuating Elsasser fields. We find significant scaling anisotropy with
+respect to both these directions: the fluctuations are ""ribbon-like"" ---
+statistically, they are elongated along both the mean magnetic field and the
+fluctuating field. The latter form of anisotropy is due to scale-dependent
+alignment of the fluctuating fields. The intermittent scalings of the
+$n$th-order conditional structure functions in the direction perpendicular to
+both the local mean field and the fluctuations agree well with the theory of
+Chandran et al. 2015, while the parallel scalings are consistent with those
+implied by the critical-balance conjecture. We quantify the relationship
+between the perpendicular scalings and those in the fluctuation and parallel
+directions, and find that the scaling exponent of the perpendicular anisotropy
+(i.e., of the aspect ratio of the Alfv\'enic structures in the plane
+perpendicular to the mean magnetic field) depends on the amplitude of the
+fluctuations. This is shown to be equivalent to the anticorrelation of
+fluctuation amplitude and alignment at each scale. The dependence of the
+anisotropy on amplitude is shown to be more significant for the anisotropy
+between the perpendicular and fluctuation-direction scales than it is between
+the perpendicular and parallel scales.",1512.01461v1
+2016-01-15,Limits on the ions temperature anisotropy in turbulent intracluster medium,"Turbulence in the weakly collisional intracluster medium of galaxies (ICM) is
+able to generate strong thermal velocity anisotropies in the ions (with respect
+to the local magnetic field direction), if the magnetic moment of the particles
+is conserved in the absence of Coulomb collisions. In this scenario, the
+anisotropic pressure magnetohydrodynamic (AMHD) turbulence shows a very
+different statistical behaviour from the standard MHD one and is unable to
+amplify seed magnetic fields, in disagreement with previous cosmological MHD
+simulations which are successful to explain the observed magnetic fields in the
+ICM. On the other hand, temperature anisotropies can also drive plasma
+instabilities which can relax the anisotropy. This work aims to compare the
+relaxation rate with the growth rate of the anisotropies driven by the
+turbulence. We employ quasilinear theory to estimate the ions scattering rate
+due to the parallel firehose, mirror, and ion-cyclotron instabilities, for a
+set of plasma parameters resulting from AMHD simulations of the turbulent ICM.
+We show that the ICM turbulence can sustain only anisotropy levels very close
+to the instabilities thresholds. We argue that the AMHD model which bounds the
+anisotropies at the marginal stability levels can describe the Alfvenic
+turbulence cascade in the ICM.",1601.03837v3
+2016-07-17,Second order perturbed Heisenberg Hamiltonian of Fe3O4 ultra-thin films,"Due to the wide range of applications, theoretical models of Fe3O4 films are
+found to be important. Ultra thin Fe3O4 films with ferrite structure have been
+theoretically investigated using second order perturbed modified Heisenberg
+Hamiltonian. Matrices for ultra thin films with two and three spin layers are
+presented in this manuscript. Total magnetic energy was expressed in terms of
+spin exchange interaction, magnetic dipole interaction, second order magnetic
+anisotropy and stress induced magnetic anisotropy. Magnetic properties were
+observed for films with two spin layers and variant second order magnetic
+anisotropy. For the film with three spin layers, second order anisotropy
+constant was fixed to avoid tedious derivations. Magnetic easy axis rotates
+toward the in plane direction as the number of spin layers is increased from
+two to three because the stress induced anisotropy energy dominates at higher
+number of spin layers. According to some other experimental data, the magnetic
+easy axis of thin films rotates toward the in plane direction as the thickness
+is increased. For ferrite film with two spin layers, magnetic easy and hard
+directions can be observed at 0.75 and 1.2 radians, respectively, when the
+ratio of stress induced anisotropy to the long range dipole interaction
+strength is 3.9. For ferrite film with three spin layers, magnetic easy and
+hard directions can be observed at 2.4 and 2.3 radians, respectively, when the
+ratio of stress induced anisotropy to the long range dipole interaction
+strength is 4.2.",1611.02225v2
+2016-12-03,Shaping the solar wind temperature anisotropy by the interplay of electron and proton instabilities,"A variety of nonthermal characteristics like kinetic, e.g., temperature,
+anisotropies and suprathermal populations (enhancing the high energy tails of
+the velocity distributions) are revealed by the in-situ observations in the
+solar wind indicating quasistationary states of plasma particles out of thermal
+equilibrium. Large deviations from isotropy generate kinetic instabilities and
+growing fluctuating fields which should be more efficient than collisions in
+limiting the anisotropy (below the instability threshold) and explain the
+anisotropy limits reported by the observations. The present paper aims to
+decode the principal instabilities driven by the temperature anisotropy of
+electrons and protons in the solar wind, and contrast the instability
+thresholds with the bounds observed at 1~AU for the temperature anisotropy. The
+instabilities are characterized using linear kinetic theory to identify the
+appropriate (fastest) instability in the relaxation of temperature anisotropies
+$A_{e,p} = T_{e,p,\perp}/ T_{e,p,\parallel} \ne 1$. The analysis focuses on the
+electromagnetic instabilities driven by the anisotropic protons ($A_p \lessgtr
+1$) and invokes for the first time a dynamical model to capture the interplay
+with the anisotropic electrons by correlating the effects of these two species
+of plasma particles, dominant in the solar wind.",1612.01012v1
+2016-12-09,Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP,"ZrMnP and HfMnP single crystals are grown by a self-flux growth technique and
+structural as well as temperature dependent magnetic and transport properties
+are studied. Both compounds have an orthorhombic crystal structure. ZrMnP and
+HfMnP are ferromagnetic with Curie temperatures around $370$~K and $320$~K
+respectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined
+to be $1.9$~$\mu_\textrm{B}$/f.u. and $2.1$~$\mu_\textrm{B}$/f.u. respectively
+at $50$~K. The magnetocaloric effect of ZrMnP in term of entropy change
+($\Delta S$) is estimated to be $-6.7$ kJm$^{-3}$K$^{-1}$ around $369$~K. The
+easy axis of magnetization is [100] for both compounds, with a small anisotropy
+relative to the [010] axis. At $50$~K, the anisotropy field along the [001]
+axis is $\sim4.6$~T for ZrMnP and $\sim10$~T for HfMnP. Such large magnetic
+anisotropy is remarkable considering the absence of rare-earth elements in
+these compounds. The first principle calculation correctly predicts the
+magnetization and hard axis orientation for both compounds, and predicts the
+experimental HfMnP anisotropy field within 25 percent. More importantly, our
+calculations suggest that the large magnetic anisotropy comes primarily from
+the Mn atoms suggesting that similarly large anisotropies may be found in other
+3d transition metal compounds.",1612.03166v1
+2017-01-25,Northern sky Galactic Cosmic Ray anisotropy between 10-1000 TeV with the Tibet Air Shower Array,"We report the analysis of the $10-1000$ TeV large-scale sidereal anisotropy
+of Galactic cosmic rays (GCRs) with the data collected by the Tibet Air Shower
+Array from October, 1995 to February, 2010. In this analysis, we improve the
+energy estimate and extend the declination range down to $-30^{\circ}$. We find
+that the anisotropy maps above 100 TeV are distinct from that at multi-TeV
+band. The so-called ""tail-in"" and ""loss-cone"" features identified at low
+energies get less significant and a new component appears at $\sim100$ TeV. The
+spatial distribution of the GCR intensity with an excess (7.2$\sigma$
+pre-trial, 5.2$\sigma$ post-trial) and a deficit ($-5.8\sigma$ pre-trial) are
+observed in the 300 TeV anisotropy map, in a good agreement with IceCube's
+results at 400 TeV. Combining the Tibet results in the northern sky with
+IceCube's results in the southern sky, we establish a full-sky picture of the
+anisotropy in hundreds of TeV band. We further find that the amplitude of the
+first order anisotropy increases sharply above $\sim100$ TeV, indicating a new
+component of the anisotropy. All these results may shed new light on
+understanding the origin and propagation of GCRs.",1701.07144v2
+2017-02-20,Recovering the mass profile and orbit anisotropy of mock dwarf galaxies with Schwarzschild modelling,"We present a new study concerning the application of the Schwarzschild orbit
+superposition method to model spherical galaxies. The method aims to recover
+the mass and the orbit anisotropy parameter profiles of the objects using
+measurements of positions and line-of-sight velocities usually available for
+resolved stellar populations of dwarf galaxies in the Local Group. To test the
+reliability of the method, we used different sets of mock data extracted from
+four numerical realizations of dark matter haloes. The models shared the same
+density profile but differed in anisotropy profiles, covering a wide range of
+possibilities, from constant to increasing and decreasing with radius. The
+tests were done in two steps, first assuming that the mass profile of the dwarf
+is known and employing the method to retrieve the anisotropy only, and then
+varying also the mass distribution. We used two kinds of data samples:
+unrealistically large ones based on over 270 000 particles from the numerical
+realizations and small ones matching the amount of data available for the
+Fornax dwarf. For the large data samples we recover both the mass and the
+anisotropy profiles with very high accuracy. For the realistically small ones
+we also find a reasonably good agreement between the fitted and the input
+anisotropies, however the total density profiles can be significantly biased as
+a result of their oversensitivity to the available data. Our results therefore
+provide convincing evidence in favour of the applicability of the Schwarzschild
+method to break the mass-anisotropy degeneracy in dwarf galaxies.",1702.06065v2
+2017-04-10,Modeling Magnetic Anisotropy of Single Chain Magnets in $|d/J| \geq 1$ Regime,"Single molecule magnets (SMMs) with single-ion anisotropies $\mathbf d$,
+comparable to exchange interactions J, between spins have recently been
+synthesized. In this paper, we provide theoretical insights into the magnetism
+of such systems. We study spin chains with site spins, s=1, 3/2 and 2 and
+on-site anisotropy $\mathbf d$ comparable to the exchange constants between the
+spins. We find that large $\mathbf d$ leads to crossing of the states with
+different $M_S$ values in the same spin manifold of the $\mathbf d = 0$ limit.
+For very large $\mathbf d$'s we also find that the $M_S$ states of the higher
+energy spin states descend below the $M_S$ states of the ground state spin
+manifold. Total spin in this limit is no longer conserved and describing the
+molecular anisotropy by the constants $D_M$ and $E_M$ is not possible. However,
+the total spin of the low-lying large $M_S$ states is very nearly an integer
+and using this spin value it is possible to construct an effective spin
+Hamiltonian and compute the molecular magnetic anisotropy constants $D_M$ and
+$E_M$. We report effect of finite sizes, rotations of site anisotropies and
+chain dimerization on the effective anisotropy of the spin chains.",1704.02825v2
+2017-06-12,Discriminating Local Sources of High-Energy Cosmic Electrons and Positrons by Current and Future Anisotropy Measurements,"The Fermi-LAT detects no significant anisotropy of the cosmic-ray (CR)
+electrons and positrons ($e^-+e^+$) with seven years of data, which provides
+the strongest restriction to the $e^-+e^+$ anisotropy up to now. As next
+generation CR observatory, HERD is expected to have a better capability of
+anisotropy detection than Fermi-LAT. In this paper, we discuss several models
+aimed to explain the AMS-02 data by the present and future anisotropy
+measurements. We find that the upper limits of Fermi-LAT disfavor Vela SNR as
+the dominant source in sub-TeV, while other cases that remain safe under the
+constraint of Fermi-LAT are expected to be distinguished from each other by
+HERD. We then discuss the possibilities of remarkable TeV spectral features,
+and test the corresponding anisotropies. We find the conditions under which the
+TeV model can have a prominent spectral feature and avoid the constraint of
+Fermi-LAT at the same time. Furthermore, the expected performance of HERD is
+sensitive enough to detect the anisotropies of all these TeV models, and even
+for the case of a featureless TeV spectrum. Thus HERD may play a crucial part
+in the study of the origin of cosmic electrons and positrons.",1706.03745v2
+2018-06-28,Readout of field induced magnetic anisotropy in a magnetoactive elastomer,"It is shown that in external magnetic fields, a uniaxial magnetic anisotropy
+comes into being in a magnetoactive elastomer (MAE). The magnitude of the
+induced uniaxial anisotropy grows with the increasing external magnetic field.
+The filler particles are immobilized in the matrix if the MAE sample is cooled
+below 220 K, where the anisotropy can be read out. The cooling of the sample is
+considered as an alternative methodological approach to the experimental
+investigation of the magnetized state of MAEs. The appearance of magnetic
+anisotropy in MAE is associated with restructuring of the filler during
+magnetization, which leads to an additional effective field felt by the
+magnetization. It is found that the magnitude of the effective magnetic
+anisotropy constant of the MAE is approximately two times larger than its
+effective shear modulus in the absence of magnetic field. It is proposed that
+the experimentally observed large (about 40) ratio of the magnetic anisotropy
+constant of the filler to the shear modulus of the matrix deserves attention
+for the explanation of magnetic and magnetoelastic properties of MAEs. It may
+lead to additional rigidity of the elastic subsystem increasing the shear
+modulus of the composite material through the magnetomechanical coupling.",1806.11014v1
+2019-03-10,The decisive role of magnetic anisotropy in honeycomb layered Li$_3$Ni$_2$SbO$_6$ and Na$_3$Ni$_2$SbO$_6$,"The decisive role of magnetic anisotropy even in systems with small
+anisotropy is illustrated for the honeycomb-layered antiferromagnets The
+decisive role of magnetic anisotropy in honeycomb layered Li$_3$Ni$_2$SbO$_6$
+and Na$_3$Ni$_2$SbO$_6$ with $A$ = Li and Na. Both systems evolve long range
+magnetic order below $T_{\rm N}$ = 14 and 16.5~K, respectively. The magnetic
+phase diagrams obtained from static magnetisation studies up to 15~T imply
+competing antiferromagnetic phases and a tricritical point at $T_{\rm N}$. The
+phase boundaries are visible in the dynamic response of the antiferromagnetic
+resonance modes, too, which investigation by means of high frequency/high field
+electron spin resonance enables precise determination of magnetic anisotropy.
+The anisotropy gap amounts to $\Delta = 360 \pm 2$~GHz in Na$_3$Ni$_2$SbO$_6$
+while in Li$_3$Ni$_2$SbO$_6$ orthorhombicity is associated with $\Delta = 198
+\pm 4$ and $218 \pm 4$~GHz. Above $T_{\rm N}$, the data imply short-range
+antiferromagnetic order up to at least 80~K. The data suggest a crucial role of
+anisotropy for selecting the actual spin structure at $B=0$~T.",1903.04041v1
+2019-04-08,Estimating the dark matter velocity anisotropy to the cluster edge,"Dark matter dominates the properties of large cosmological structures such as
+galaxy clusters, and the mass profiles of the dark matter have been measured
+for these equilibrated structures for years using X-rays, lensing or galaxy
+velocities. A new method has been proposed, which should allow us to estimate a
+dynamical property of the dark matter, namely the velocity anisotropy. For the
+gas a similar velocity anisotropy is zero due to frequent collisions, however,
+the collisionless nature of dark matter allows it to be non-trivial. Numerical
+simulations have for years found non-zero and radially varying dark matter
+velocity anisotropies. Here we employ the method proposed by Hansen and
+Pifaretti (2007), and developed by Host et al. (2009) to estimate the dark
+matter velocity anisotropy in the bright galaxy cluster Perseus, to near 5
+times the radii previously obtained. We find the dark matter velocity
+anisotropy to be consistent with the results of numerical simulations, however,
+still with large error-bars. At half the virial radius we find the velocity
+anisotropy to be non-zero at 1.7 standard deviations, lending support to the
+collisionless nature of dark matter.",1904.04260v3
+2019-08-09,Magnetic and thermodynamic properties of the octanuclear nickel phosphonate-based cage,"We report a detailed theoretical investigation into the influence of
+anisotropy on the magnetic and thermodynamic properties of an octanuclear
+nickel phosphonate cage with butterfly-shaped molecular geometry, namely
+$\mathrm{Ni}_8(\mu_3-\mathrm{OH})_4(\mathrm{OMe})_2(\mathrm{O}_3\mathrm{PR}_1)_2
+(\mathrm{O}_2\mathrm{C}^t\mathrm{Bu})_6
+(\mathrm{HO}_2\mathrm{C}^t\mathrm{Bu})_8$. To validate our exact
+diagonalization approach, we firstly compare results with simulations and
+experiment in the isotropic case. Having established concurrence, we then
+introduce uniaxial single-ion anisotropy and Heisenberg exchange anisotropy
+between interacted nickel atoms. We then examine effects of both anisotropy
+parameters on the magnetization process, as well as on the specific heat of the
+model. We predict intermediate magnetization plateaus, including zero plateau,
+and magnetization jumps with magnetic ground-state phase transitions at low
+temperature $T=1$K. The magnetization plateaus are strongly dependent on both
+the levels of exchange anisotropy and single-ion anisotropy. Varying the former
+leads to change in width and magnetic position of all intermediate plateaus
+while they become wider upon increasing the latter. The specific heat of the
+model manifests a Schottky-type maximum at moderate temperature in the presence
+of weak magnetic fields, when the system is isotropic. The introducion of
+aniostropy results in substantial variations in the thermal behavior of the
+specific heat. Indeed, by tuning anisotropy parameters the Schottky peak
+convert to a double-peak temperature dependence that coincided with the
+magnetization jumps. We call for these theoretical predictions to be verified
+experimentally at low temperature.",1908.03614v2
+2020-05-30,Re-Examining the Evidence of the Hercules-Corona-Borealis Great Wall,"In the {\Lambda}-CDM paradigm of cosmology, anisotropies larger than 260 Mpc
+shouldn't exist. However, the existence of the Hercules-Corona Borealis Great
+Wall (HCB) is purported to challenge this principle by some with an estimated
+size exceeding 2000 Mpc. Recently, some have challenged the assertion of the
+existence of the HCB, attributing the anisotropy to sky exposure effects. It
+has never been explained why the original methods purporting the existence of
+the HCB produce anisotropies, even if sky-exposure effects are taken into
+account. In this paper, I apply the methods of the original papers purporting
+the existence of the HCB in various Monte-Carlo simulations that assume
+isotropy to analyze the empirical meaning of the significance levels of the
+original tests used. I find that, although the statistical tests at first
+glance show significant anisotropies present in the suspect sample, Monte-Carlo
+simulations can easily reproduce the sample in most cases, and if not, the
+differences can be accounted for by other statistical considerations. An
+updated sample raises the probability of drawing the observed clustering from
+an isotropic sample ten-fold in some cases. Thus the statistical tests used in
+prior studies overestimate the significance of the observed anisotropy, and an
+updated sample returns even less significant probabilities. Given the ability
+to reproduce the observed anisotropy in Monte-Carlo simulations, the new,
+higher probabilities of being drawn from isotropy for an updated sample, and
+the work of previous papers attributing anisotropies to sky-selection effects,
+the existence of the HCB must be treated as doubtful at best.",2006.00141v1
+2020-05-30,Magnetization dynamics in proximity-coupled superconductor/ferromagnet/superconductor multilayers,"In this work, magnetization dynamics is studied in
+superconductor/ferromagnet/superconductor three-layered films in a wide
+frequency, field, and temperature ranges using the broad-band ferromagnetic
+resonance measurement technique. It is shown that in presence of both
+superconducting layers and of superconducting proximity at both
+superconductor/ferromagnet interfaces a massive shift of the ferromagnetic
+resonance to higher frequencies emerges. The phenomenon is robust and
+essentially long-range: it has been observed for a set of samples with the
+thickness of ferromagnetic layer in the range from tens up to hundreds of
+nanometers. The resonance frequency shift is characterized by proximity-induced
+magnetic anisotropies: by the positive in-plane uniaxial anisotropy and by the
+drop of magnetization. The shift and the corresponding uniaxial anisotropy grow
+with the thickness of the ferromagnetic layer. For instance, the anisotropy
+reaches 0.27~T in experiment for a sample with 350~nm thick ferromagnetic
+layer, and about 0.4~T in predictions, which makes it a ferromagnetic film
+structure with the highest anisotropy and the highest natural resonance
+frequency ever reported. Various scenarios for the superconductivity-induced
+magnetic anisotropy are discussed. As a result, the origin of the phenomenon
+remains unclear. Application of the proximity-induced anisotropies in
+superconducting magnonics is proposed as a way for manipulations with a
+spin-wave spectrum.",2006.00348v1
+2020-06-10,Dynamical masses of brightest cluster galaxies I: stellar velocity anisotropy and mass-to-light ratios,"We investigate the stellar and dynamical mass profiles in the centres of 25
+brightest cluster galaxies (BCGs) at redshifts of 0.05 $\leq z \leq$ 0.30. Our
+spectroscopy enables us to robustly measure the Gauss-Hermite higher order
+velocity moments $h_{3}$ and $h_{4}$, which we compare to measurements for
+massive early-type galaxies, and central group galaxies. We measure positive
+central values for $h_{4}$ for all the BCGs. We derive the stellar
+mass-to-light ratio ($\Upsilon_{\star \rm DYN}$), and velocity anisotropy
+($\beta$) based on a Multi-Gaussian Expansion (MGE) and axisymmetric Jeans
+Anisotropic Methods (JAM, cylindrically- and spherically-aligned). We
+explicitly include a dark matter halo mass component, which is constrained by
+weak gravitational lensing measurements for these clusters. We find a strong
+correlation between anisotropy and velocity dispersion profile slope, with
+rising velocity dispersion profiles corresponding to tangential anisotropy and
+decreasing velocity dispersion profiles corresponding to radial anisotropy. The
+rising velocity dispersion profiles can also indicate a significant
+contribution from the intracluster light (ICL) to the total light (in
+projection) in the centre of the galaxy. For a small number of BCGs with rising
+velocity dispersion profiles, a variable stellar mass-to-light ratio can also
+account for the profile shape, instead of tangential anisotropy or a
+significant ICL contribution. We note that, for some BCGs, a variable
+$\beta_{z}(r)$ (from radial to tangential anisotropy) can improve the model fit
+to the observed kinematic profiles. The observed diversity in these properties
+illustrates that BCGs are not the homogeneous class of objects they are often
+assumed to be.",2006.05706v1
+2020-09-22,Numerical equilibria with pressure anisotropy and incompressible plasma rotation parallel to the magnetic field,"It is believed that plasma rotation can affect the transitions to the
+advanced confinement regimes in tokamaks. In addition, in order to achieve
+fusion temperatures modern tokamaks rely on auxiliary heating methods. These
+methods generate pressure anisotropy in the plasma. For incompressible rotation
+with pressure anisotropy the equilibrium is governed by a Generalized
+Grad-Shafranov (GGS) equation and a decoupled Bernoulli-type equation for the
+effective pressure, $\bar{p}=(p_\parallel+p_\perp)/2$, where $p_\parallel$
+($p_\perp$) is the pressure tensor element parallel (perpendicular) to the
+magnetic field. In the case of plasma rotation parallel to the magnetic field
+the GGS equation can be transformed to one equation identical in form with the
+GS equation. In this study by making use of the aforementioned property of the
+GGS equation for parallel plasma rotation we have constructed ITER-like
+numerical equilibria by extending HELENA, an equilibrium fixed-boundary solver
+and examined the impact of rotation and anisotropy on certain equilibrium
+quantities. The main conclusions are that the addition of pressure anisotropy
+to rotation allows the profile shaping of the equilibrium quantities in much
+more extent thus favouring the confinement and allows extension of the
+parametric space of the Mach number corresponding to higher values.
+Furthermore, the impact of pressure anisotropy in the equilibrium quantities is
+stronger than that of the rotation, for most of the quantities examined. For
+the pressure components the impact of the pressure anisotropy is the same
+regardless of whether the power is deposited parallel or perpendicular to the
+magnetic surfaces, thus implying that there is no preferable heating direction,
+while for the current density, the heating parallel to the magnetic surfaces
+seems to be beneficial for the current-gradient driven instabilities.",2009.10422v1
+2020-10-19,From high $p_\perp$ theory and data to inferring anisotropy of Quark-Gluon Plasma,"High $p_\perp$ theory and data are commonly used to study high $p_\perp$
+parton interactions with QGP, while low $p_\perp$ data and corresponding models
+are employed to infer QGP bulk properties. On the other hand, with a proper
+description of high $p_\perp$ parton-medium interactions, high $p_\perp$ probes
+become also powerful tomography tools, since they are sensitive to global QGP
+features, such as different temperature profiles or initial conditions. This
+tomographic role of high $p_\perp$ probes can be utilized to assess the spatial
+anisotropy of the QCD matter. With our dynamical energy loss formalism, we show
+that a (modified) ratio of $R_{AA}$ and $v_2$ presents a reliable and robust
+observable for straightforward extraction of initial state anisotropy. We
+analytically estimated the proportionality between the $v_2/(1-R_{AA})$ and
+anisotropy coefficient $\epsilon_{2L}$, and found surprisingly good agreement
+with full-fledged numerical calculations. Within the current error bars, the
+extraction of the anisotropy from the existing data using this approach is
+still inaccessible. However, with the expected accuracy improvement in the
+upcoming LHC runs, the anisotropy of the QGP formed in heavy ion collisions can
+be straightforwardly derived from the data. Such a data-based anisotropy
+parameter would present an important test to models describing the initial
+stages of heavy-ion collision and formation of QGP, and demonstrate the
+usefulness of high $p_\perp$ theory and data in obtaining QGP properties.",2010.09773v1
+2020-11-02,The chain length of anisotropic paramagnetic particles in a rotating field,"In this article, the maximal length of a chain of paramagnetic particles with
+magnetic anisotropy in a rotating magnetic field is studied. The theory of
+paramagnetic particle chains usually assumes that the particles are
+magnetically isotropic and do not rotate in a rotating field. In experiments it
+is seen that spherical paramagnetic particles rotate, which can be explained by
+small magnetic anisotropy. In this article, the maximal chain length is
+calculated for paramagnetic particles with magnetic anisotropy in a rotating
+magnetic field. Results show that the maximal chain length as a function of
+field frequency has the same trend for isotropic magnetic particles and
+particles with magnetic anisotropy if the field frequency is much higher or
+much lower than the critical frequency of an individual particle. blue
+Initially randomly distributed particles will form chains that will collide and
+exchange with particles till they obtain a typical chain length. The typical
+chain length of a small cluster is shorter than the maximal chain length of an
+isolated chain for the same field frequency. The distribution of chain lengths
+in a small cluster of chains is narrower for particles with higher magnetic
+anisotropy. Due to the narrower distribution of chain lengths, particles with
+magnetic anisotropy can suit better for mass-production. This article will show
+how magnetic anisotropy parameters of paramagnetic particles influence chain
+length of chains which form in a rotating magnetic field.",2011.01003v2
+2020-12-23,Small-scale CMB anisotropies induced by the primordial magnetic fields,"The primordial magnetic fields (PMFs) produced in the early universe are
+expected to be the origin of the large-scale cosmic magnetic fields. The PMFs
+are considered to leave a footprint on the cosmic microwave background (CMB)
+anisotropies due to both the electromagnetic force and gravitational
+interaction. In this paper, we investigate how the PMFs affect the CMB
+anisotropies on smaller scales than the mean-free-path of the CMB photons. We
+solve the baryon Euler equation with Lorentz force due to the PMFs, and we show
+that the vector-type perturbations from the PMFs induce the CMB anisotropies
+below the Silk scale as $\ell>3000$. Based on our calculations, we put a
+constraint on the PMFs from the combined CMB temperature anisotropies obtained
+by Planck and South Pole Telescope (SPT). We have found that the
+highly-resolved temperature anisotropies of the SPT 2017 bandpowers at $\ell
+\lesssim 8000$ favor the PMF model with a small scale-dependence. As a result,
+the Planck and SPT's joint-analysis puts a constraint on the PMF spectral index
+as $n_B<-1.14$ at 95% confidence level (C.L.), and this is more stringent
+compared with the Planck-only constraint $n_B<-0.28$. We show that the PMF
+strength normalized on the co-moving 1 Mpc scale is also tightly constrained as
+$B_{1\mathrm{Mpc}}<1.5$ nG with Planck and SPT at 95% C.L., while
+$B_{1\mathrm{Mpc}}<3.2$ nG only with the Planck data at 95% C.L. We also
+discuss the effects on the cosmological parameter estimate when including the
+SPT data and CMB anisotropies induced by the PMFs.",2012.12542v2
+2021-10-01,Statistically study the optimal local sources for cosmic ray nuclei and electron,"The local sources, such as Geminga SNR, may play important role for the
+anomaly of proton, electron and anisotropy in the past works. In fact, there
+exists twelve SNRs around solar system within $1$ kpc. One question is that can
+other SNRs also possibly contribute the spectra of nuclei and electron and
+explain the special structure of anisotropy? In this work, under the
+spatial-dependent propagation, we systematically study the contribution of all
+local SNRs within 1 kpc around solar to the spectra of nuclei and electron, as
+well as the energy dependence of anisotropy. As a result, only Geminga,
+Monogem, and Vela SNRs have quantitive contribution to the nuclei and electron
+spectra and anisotropy. Here, Geminga SNR is the sole optimal candidate and
+Monogem SNR is controversial due to the tension of anisotropy between model
+calculation and observations. The Vela SNR contributes a new spectral structure
+beyond TeV energy, hinted by HESS, VERITAS, DAMPE and CALET measurements. More
+interesting is that the electron anisotropy satisfies the Fermi-LAT limit below
+TeV energy, but rises greatly and reaches $10\%$ at several TeV. This new
+structure will shed new light to check our model. We hope that the new
+structure of electron spectrum and anisotropy can be observed by space-borne
+DAMPE and HERD and ground-based HAWC and LHAASO experiments in the near future.",2110.00501v2
+2021-12-02,Anisotropy of phase transition gravitational wave and its implication for primordial seeds of the Universe,"We quantitatively study how the primordial density fluctuations are imprinted
+on the anisotropy of the phase transition gravitational wave (PTGW). Generated
+long before recombination and free from Silk damping, the anisotropic PTGW
+might reveal the density perturbation seeded from inflation or alternatives. We
+find new behaviors of the PTGW anisotropy power spectrum. The PTGW anisotropy
+is stronger than the anisotropy of the cosmic microwave background temperature
+at all scales, and the high-$\ell$ multiples are enhanced about 1 order due to
+the early integrated Sachs-Wolfe effect. Furthermore, differences in primordial
+power spectra at small scales manifest themselves more significantly on the
+angular power spectrum of PTGW anisotropy compared to that of the cosmic
+microwave background. These properties might provide a novel clue to
+understanding the primordial density perturbation of our early Universe and
+thereby complete our understanding of inflation theory. Taking nanohertz PTGW
+from dark matter models as a typical example, we obtain amplitudes of PTGW
+anisotropy which are about 4 or 3 orders weaker than the isotropic PTGW energy
+spectra.",2112.01409v4
+2022-01-17,Understanding the phase reversals of Galactic cosmic ray anisotropies,"The energy spectra and anisotropies are very important probes of the origin
+of cosmic rays. Recent measurements show that complicated but very interesting
+structures exist, at similar energies, in both the spectra and energy-dependent
+anisotropies, indicating a common origin of these structures. Particularly
+interesting phenomenon is that there is a reversal of the phase of the dipole
+anisotropies, which challenges a theoretical modeling. In this work, for the
+first time, we identify that there might be an additional phase reversal at
+$\sim 100$ GeV energies of the dipole anisotropies as indicated by a few
+underground muon detectors and the first direct measurement by the Fermi
+satellite, coincident with the hundreds of GV hardenings of the spectra. We
+propose that these two phase reversals, together with the energy-evolution of
+the amplitudes and spectra, can be naturally explained with a nearby source
+overlapping onto the diffuse background. As a consequence, the spectra and
+anisotropies can be understood as the scalar and vector components of this
+model, and the two reversals of the phases characterize just the competition of
+the cosmic ray streamings between the nearby source and the background. The
+alignment of the cosmic ray streamings along the local large-scale magnetic
+field may play an important but sub-dominant role in regulating the cosmic ray
+propagation. More precise measurements of the anisotropy evolution at both low
+energies by space detectors and high energies by air shower experiments for
+individual species will be essential to further test this scenario.",2201.06234v2
+2022-02-15,Investigation of the magnetoelastic coupling anisotropy in the Kitaev material $α$-RuCl$_3$,"The Kitaev material $\alpha$-RuCl$_3$ is among the most prominent candidates
+to host a quantum spin-liquid state endowed with fractionalized excitations.
+Recent experimental and theoretical investigations have separately revealed the
+importance of both the magnetoelastic coupling and the magnetic anisotropy, in
+dependence of the applied magnetic field direction. In this combined
+theoretical and experimental research, we investigate the anisotropic magnetic
+and magnetoelastic properties for magnetic fields applied along the main
+crystallographic axes as well as for fields canted out of the honeycomb plane.
+We found that the magnetostriction anisotropy is unusually large compared to
+the anisotropy of the magnetization, which is related to the strong
+magnetoelastic $\widetilde{\Gamma'}$-type coupling in our \textit{ab-initio}
+derived model. We observed large, non-symmetric magnetic anisotropy for
+magnetic fields canted out of the honeycomb $ab$-plane in opposite directions,
+namely towards the $+c^*$ or $-c^*$ axes, respectively. The observed
+directional anisotropy is explained by considering the relative orientation of
+the magnetic field with respect to the co-aligned RuCl$_6$ octahedra.
+Magnetostriction measurements in canted fields support this non-symmetric
+magnetic anisotropy, however these experiments are affected by magnetic torque
+effects. Comparison of theoretical predictions with experimental findings allow
+us to recognize the significant contribution of torque effects in experimental
+setups where $\alpha$-RuCl$_3$ is placed in canted magnetic fields.",2202.07102v1
+2022-04-07,Orientation Controlled Anisotropy in Single Crystals of Quasi-1D BaTiS3,"Low-dimensional materials with chain-like (one-dimensional) or layered
+(twodimensional) structures are of significant interest due to their
+anisotropic electrical, optical, thermal properties. One material with
+chain-like structure, BaTiS3 (BTS), was recently shown to possess giant
+in-plane optical anisotropy and glass-like thermal conductivity. To understand
+the origin of these effects, it is necessary to fully characterize the optical,
+thermal, and electronic anisotropy of BTS. To this end, BTS crystals with
+different orientations (aand c-axis orientations) were grown by chemical vapor
+transport. X-ray absorption spectroscopy (XAS) was used to characterize the
+local structure and electronic anisotropy of BTS. Fourier transform infrared
+(FTIR) reflection/transmission spectra show a large inplane optical anisotropy
+in the a-oriented crystals, while the c-axis oriented crystals were nearly
+isotropic in-plane. BTS platelet crystals are promising uniaxial materials for
+IR optics with their optic axis parallel to the c-axis. The thermal
+conductivity measurements revealed a thermal anisotropy of ~4.5 between the c-
+and a-axis. Time-domain Brillouin scattering showed that the longitudinal sound
+speed along the two axes is nearly the same suggesting that the thermal
+anisotropy is a result of different phonon scattering rates.",2204.03680v1
+2022-08-22,Monte Carlo study of the phase transitions in the classical XY ferromagnets with random anisotropy,"The three-dimensional anisotropic classical XY ferromagnet has been
+investigated by extensive Monte Carlo simulation using the Metropolis single
+spin flip algorithm. The magnetization ($M$) and the susceptibility ($\chi$)
+are measured and studied as functions of the temperature of the system. For
+constant anisotropy, the ferro-para phase transition has been found to take
+place at a higher temperature than that observed in the isotropic case. The
+system gets ordered at higher temperatures for higher values of the strength of
+anisotropy. The opposite scenario is observed in the case of random anisotropy.
+For all three different kinds of statistical distributions (uniform, Gaussian,
+and bimodal) of random anisotropy, the system gets ordered at lower
+temperatures for higher values of the width of the distribution of anisotropy.
+We have provided the phase boundaries in the case of random anisotropy. The
+critical exponents for the scaling laws $M \sim L^{-{{\beta} \over {\nu}}}$ and
+$\chi \sim L^{{{\gamma} \over {\nu}}} $ are estimated through the finite size
+analysis.",2208.10109v8
+2022-09-01,Towards Morphologically Induced Anisotropy in Thermally Hysteretic Dielectric Properties of Vanadium Dioxide,"The Bruggeman homogenization formalism was used to numerically investigate
+the dielectric properties of a columnar thin film (CTF) made from vanadium
+dioxide. For visible and near-infrared wavelengths, the CTF is
+electromagnetically equivalent to a homogeneous orthorhombic material. Over the
+58 deg C -- 72 deg C temperature range, the eigenvalues of the CTF's relative
+permittivity dyadic are highly sensitive to temperature, and vary according to
+whether the CTF is being heated or cooled. The anisotropy revealed through the
+eigenvalues, and the anisotropy of the associated hysteresis, were investigated
+in relation to temperature for CTFs of different porosities and columnar cross
+sections. When the free-space wavelength is 800 nm, the CTF is a dissipative
+dielectric material that exhibits temperature-dependent anisotropy and
+anisotropic hysteresis. In contrast, when the free-space wavelength is 1550 nm,
+the CTF can be either a dissipative dielectric material, a hyperbolic material
+or a metal-like material, depending on the temperature and the porosity of the
+CTF. As the porosity of the CTF decreases from 0.55 to 0.3, the anisotropy of
+the CTF becomes more pronounced, as does the anisotropy of the hysteresis. Only
+relatively modest variations in anisotropy and hysteresis arise in response to
+varying the columnar cross-sectional shape, as compared to the variations
+induced by varying the porosity.",2209.00492v1
+2023-01-22,FCC structured ferromagnetic ultra-thin films with two spin layers described by fourth order perturbed Heisenberg Hamiltonian,"Fourth order perturbation was applied to study a small variation of the
+azimuthal angle of spin of fcc structured ferromagnetic thin films with two
+spin layers. The variation of magnetic energy and the orientation of magnetic
+easy axis with the fourth order magnetic anisotropy constant in two spin layers
+was investigated. When the second order magnetic anisotropy constant at the top
+spin layer is higher than that of bottom spin layer, the total magnetic energy
+is slightly higher. Some spikes appeared in the 2D plot of of magnetic energy
+versus azimuthal angle of spin. According to the 3D plots, the peak value of
+the magnetic energy gradually decreases with the increase of the stress induced
+anisotropy constant, and thereafter the peak value of the magnetic energy
+gradually increases with the increase of the stress induced anisotropy
+constant. The angle between magnetic easy and hard directions was not 90
+degrees. The magnetic easy and hard directions of the film with a higher second
+order magnetic anisotropy constant of top layer are different from the magnetic
+easy and hard directions of the film with a lower second order magnetic
+anisotropy constant of top layer. When the second order magnetic anisotropy
+constant of the bottom layer is increased, the total magnetic energy does not
+change.",2301.09137v1
+2023-10-11,Flux gradient relations and their dependence on turbulence anisotropy,"Monin-Obukhov similarity theory (MOST) is used in virtually every Earth
+System Model (ESM) to parameterize the near-surface turbulent exchanges,
+however there is high uncertainty in the literature about the appropriate
+parameterizations to be used. In addition, MOST has limitations in very stable
+and unstable regimes, over heterogeneous terrain and complex orography, and has
+been found to incorrectly represent the surface fluxes. A new approach
+including turbulence anisotropy as a scaling parameter has recently been
+developed, allowing to overcome these limitations and generalize the
+flux-variance relations to complex terrain. In this paper we analyze the
+flux-gradient relations for five well known datasets. The scaling relations
+show substantial scatter and highlight the uncertainty in the choice of
+parameterization even over canonical conditions. We show that by including
+information on turbulence anisotropy as an additional scaling parameter, the
+original scatter becomes well bounded and new formulations can be developed,
+that drastically improve the accuracy of the flux-gradient relations for wind
+shear ($\phi_M$) in unstable conditions, and for temperature gradient
+($\phi_H$) both in unstable and stable regime. This analysis shows that both
+$\phi_M$ and $\phi_H$ are strongly dependent on turbulence anisotropy and
+allows to finally settle the longly discussed free convection regime for
+$\phi_M$, which clearly exhibits a $-{1/3}$ power law when anisotropy is
+accounted for. Furthermore we show that the eddy diffusivities for momentum and
+heat and the turbulent Prandtl number are strongly dependent on anisotropy and
+that the latter goes to zero in the free convection limit. These results
+highlight the necessity to include anisotropy in the study of near surface
+atmospheric turbulence and lead the way for theoretically more robust
+simulations of the boundary layer over complex terrain.",2310.07503v1
+2023-12-01,Hydrogen-induced switching of perpendicular magnetic anisotropy in amorphous ferrimagnetic thin films,"Unraveling the mechanisms responsible for perpendicular magnetic anisotropy
+(PMA) in amorphous rare earth-transition metal alloys has proven challenging,
+primarily due to the intrinsic complexity of the amorphous structure. Here, we
+investigated the atomic origin of PMA by applying an approach of voltage-driven
+hydrogen insertion in interstitial sites, which serve as a perturbation and
+probe in local atomic structure. After hydrogen charging, PMA in amorphous TbCo
+thin films diminished and switched to in-plane anisotropy, accompanied by
+distinct magnetic domain structures. By analyzing the mechanism behind the
+anisotropy switching, we unveiled the decisive role of Tb-Co/Tb-Tb bonding in
+shaping the magnetic anisotropy using both angle-dependent X-ray magnetic
+dichroism and ab initio calculations. Hydrogen insertion induced a
+reorientation of the local anisotropy axis, initially along the Tb-Co bonding
+direction, due to the distortion of crystal field around Tb. Our approach not
+only shows the atomic origin of Tb-Co bonding in inducing PMA, but also enables
+the voltage-driven tailoring of magnetic anisotropy in amorphous alloys.",2312.00643v1
+2024-02-27,Measuring kinematic anisotropies with pulsar timing arrays,"Recent Pulsar Timing Array (PTA) collaborations show strong evidence for a
+stochastic gravitational wave background (SGWB) with the characteristic
+Hellings-Downs inter-pulsar correlations. The signal may stem from supermassive
+black hole binary mergers, or early universe phenomena. The former is expected
+to be strongly anisotropic while primordial backgrounds are likely to be
+predominantly isotropic with small fluctuations. In case the observed SGWB is
+of cosmological origin, our relative motion with respect to the SGWB rest frame
+is a guaranteed source of anisotropy, leading to $\mathcal{O}(10^{-3})$ energy
+density fluctuations of the SGWB. These kinematic anisotropies are likely to be
+larger than the intrinsic anisotropies, akin to the cosmic microwave background
+(CMB) dipole anisotropy. We assess the sensitivity of current PTA data to the
+kinematic dipole anisotropy and also provide forecasts with which the magnitude
+and direction of the kinematic dipole may be measured in the future with an
+SKA-like experiment. We also discuss how the spectral shape of the SGWB and the
+location of pulsar observed affects the prospects of detecting the kinematic
+dipole with PTA. A detection of this anisotropy may even help resolve the
+discrepancy in the magnitude of the kinematic dipole as measured by CMB and
+large-scale structure observations.",2402.17312v1
+2010-05-03,Tailoring magnetic anisotropy in epitaxial half metallic La0.7Sr0.3MnO3 thin films,"We present a detailed study on the magnetic properties, including anisotropy,
+reversal fields, and magnetization reversal processes, of well characterized
+half-metallic epitaxial La0.7Sr0.3MnO3 (LSMO) thin films grown onto SrTiO3
+(STO) substrates with three different surface orientations, i.e. (001), (110)
+and (1-18). The latter shows step edges oriented parallel to the [110]
+(in-plane) crystallographic direction. Room temperature high resolution
+vectorial Kerr magnetometry measurements have been performed at different
+applied magnetic field directions in the whole angular range. In general, the
+magnetic properties of the LSMO films can be interpreted with just the uniaxial
+term with the anisotropy axis given by the film morphology, whereas the
+strength of this anisotropy depends on both structure and film thickness. In
+particular, LSMO films grown on nominally flat (110)-oriented STO substrates
+presents a well defined uniaxial anisotropy originated from the existence of
+elongated in-plane [001]-oriented structures, whereas LSMO films grown on
+nominally flat (001)-oriented STO substrates show a weak uniaxial magnetic
+anisotropy with the easy axis direction aligned parallel to residual substrate
+step edges. Elongated structures are also found for LSMO films grown on vicinal
+STO(001) substrates. These films present a well-defined uniaxial magnetic
+anisotropy with the easy axis lying along the step edges and its strength
+increases with the LSMO thickness. It is remarkable that this step-induced
+uniaxial anisotropy has been found for LSMO films up to 120 nm thickness. Our
+results are promising for engineering novel half-metallic magnetic devices that
+exploit tailored magnetic anisotropy.",1005.0553v3
+2017-06-02,Small-scale anisotropy induced by spectral forcing and by rotation in non-helical and helical turbulence,"We study the effect of large-scale spectral forcing on the scale-dependent
+anisotropy of the velocity field in direct numerical simulations of homogeneous
+incompressible turbulence. Two forcing methods are considered: the steady ABC
+single wavenumber scheme and the unsteady non-helical or helical Euler scheme.
+The results are also compared with high resolution data obtained with the
+negative viscosity scheme. A fine-grained characterization of anisotropy,
+consisting in measuring some quantities related to the two-point velocity
+correlations, is used: we perform a modal decomposition of the spectral
+velocity tensor into energy, helicity and polarization spectra. Moreover, we
+include the explicit dependence of these three spectra on the wavevector
+direction. The conditions that allow anisotropy to develop in the small scales
+due to forcing alone are clearly identified. It is shown that, in turbulent
+flows expected to be isotropic, the ABC forcing yields significant energy and
+helicity directional anisotropy down to the smallest resolved scales, like the
+helical Euler scheme when an unfavourable forcing scale is used. The
+direction-and scale-dependent anisotropy is then studied in rotating
+turbulence. It is first shown that, in the ABC-forced simulations the slope of
+the energy spectrum is altered and the level of anisotropy is similar to that
+obtained at lower Rossby number in Euler-forced runs, a result due both to the
+nature of the forcing itself and to the fact that it allows an inverse cascade
+to develop. Second, we show that, even at low rotation rate, the natural
+anisotropy induced by the Coriolis force is visible at all scales. Finally, we
+identify two different wavenumber ranges in which anisotropy behaves
+differently, and show that if the Rossby number is not too low the
+characteristic lenghscale separating them is the one at which rotation and
+dissipation effects balance.",1706.00651v1
+2022-10-07,Giant and tunable excitonic optical anisotropy in single-crystal CsPbX$_3$ halide perovskites,"During the last years, giant optical anisotropy demonstrated its paramount
+importance for light manipulation which resulted in numerous applications
+ranging from subdiffraction light guiding to switchable nanolasers. In spite of
+recent advances in the field, achieving continuous tunability of optical
+anisotropy remains an outstanding challenge. Here, we present a solution to the
+problem through chemical alteration of the ratio of halogen atoms (X = Br or
+Cl) in single-crystal CsPbX$_3$ halide perovskites. It turns out that the
+anisotropy originates from an excitonic resonance in the perovskite, which
+spectral position and strength are determined by the halogens composition. As a
+result, we manage to continually modify the optical anisotropy by 0.14. We also
+discover that the halide perovskite can demonstrate optical anisotropy up to
+0.6 in the visible range -- the largest value among non-van der Waals
+materials. Moreover, our results reveal that this anisotropy could be in-plane
+and out-of-plane, depending on perovskite shape -- rectangular and square.
+Hence, it can serve as an additional degree of freedom for anisotropy
+manipulation. As a practical demonstration, we created perovskite anisotropic
+nanowaveguides and show a significant impact of anisotropy on high-order
+guiding modes. These findings pave the way for halide perovskites as a
+next-generation platform for tunable anisotropic photonics.",2210.03541v1
+1994-11-01,Toward Understanding CMB Anisotropies and Their Implications,"Working toward a model independent understanding of cosmic microwave
+background (CMB) anisotropies and their significance, we undertake a
+comprehensive and self-contained study of scalar perturbation theory. Initial
+conditions, evolution, thermal history, matter content, background dynamics,
+and geometry all play a role in determining the anisotropy. By employing {\it
+analytic} techniques to illuminate the numerical results, we are able to
+separate and identify each contribution. We thus bring out the nature of the
+{\it total} Sachs-Wolfe effect, acoustic oscillations, diffusion damping,
+Doppler shifts, and reionization, as well as their particular manifestation in
+a critical, curvature, or cosmological constant dominated universe. By studying
+the full angular {\it and} spatial content of the resultant anisotropies, we
+isolate the signature of these effects from the dependence on initial
+conditions. Whereas structure in the Sachs-Wolfe anisotropy depends strongly on
+the underlying power spectra, the acoustic oscillations provide features which
+are nearly model independent. This may allow for future determination of the
+matter content of the universe as well as the adiabatic and/or isocurvature
+nature of the initial fluctuations.",9411008v1
+1995-01-17,The Imprint of Proper Motion of Nonlinear Structures on the Cosmic Microwave Background,"We investigate the imprint of nonlinear matter condensations on the Cosmic
+Microwave Background (CMB) in an $\Omega=1$, Cold Dark Matter (CDM) model
+universe. Temperature anisotropies are obtained by numerically evolving matter
+inhomogeneities and CMB photons from the beginning of decoupling until the
+present epoch. The underlying density field produced by the inhomogeneities is
+followed from the linear, through the weakly clustered, into the fully
+nonlinear regime. We concentrate on CMB temperature distortions arising from
+variations in the gravitational potentials of nonlinear structures. We find two
+sources of temperature fluctuations produced by time-varying potentials: (1)
+anisotropies due to intrinsic changes in the gravitational potentials of the
+inhomogeneities and (2) anisotropies generated by the peculiar, bulk motion of
+the structures across the microwave sky. Both effects generate CMB anisotropies
+in the range of $10^{-7} \siml \Delta T/T \siml 10^{-6}$ on scales of $ \sim
+1^{\circ}$. For isolated structures, anisotropies due to proper motion exhibit
+a dipole-like signature in the CMB sky that in principle could yield
+information on the transverse velocity of the structures.",9501059v1
+1995-10-24,Anisotropy and inhomogeneity of the universe from $ΔT/T$,"A recent paper (Martinez--Gonzalez & Sanz 1995) showed that if the universe
+is homogeneous but anisotropic, then the small quadrupole anisotropy in the
+cosmic microwave background radiation implies that the spacetime anisotropy is
+very small. We point out that more general results may be established, without
+assuming a priori homogeneity. We have proved that small anisotropies in the
+microwave background imply that the universe is almost
+Friedmann--Robertson--Walker. Furthermore, the quadrupole and octopole place
+direct and explicit limits on the degree of anisotropy and inhomogeneity, as
+measured by the shear, vorticity, Weyl tensor and density gradients. In the
+presence of inhomogeneity, it is only possible to set a much weaker limit on
+the shear than that given by Martinez--Gonzalez & Sanz.",9510126v1
+1996-03-22,Contribution of Extragalactic Infrared Sources to CMB Foreground Anisotropy,"We estimate the level of confusion to Cosmic Microwave Background anisotropy
+measurements caused by extragalactic infrared sources. CMB anisotropy
+observations at high resolution and high frequencies are especially sensitive
+to this foreground. We use data from the COBE satellite to generate a Galactic
+emission spectrum covering mm and sub-mm wavelengths. Using this spectrum as a
+template, we predict the microwave emission of the 5319 brightest infrared
+galaxies seen by IRAS. We simulate skymaps over the relevant range of
+frequencies (30-900 GHz) and instrument resolutions (10'-10 degrees Full Width
+Half Max). Analysis of the temperature anisotropy of these skymaps shows that a
+reasonable observational window is available for CMB anisotropy measurements.",9603121v2
+1996-09-21,CMB anisotropy at degree angular scales and the thermal history of the Universe,"We study the anisotropy of the cosmic microwave background (CMB) in cold and
+mixed dark matter (CDM and MDM) models, with non scale-invariant primordial
+power spectra (i.e. $n \neq 1$) and a late, sudden reionization of the
+intergalactic medium at redshift $z_{rh}$. We test these models against recent
+detections of CMB anisotropy at large and intermediate angular scales. We find
+that current CMB anisotropy measurements cannot discriminate between CDM and
+MDM models. Our likelihood analysis indicates that models with blue power
+spectra ($n \simeq 1.2$) and a reionization at $z_{rh} \sim 20$ are most
+consistent with the anisotropy data considered here. Without reionization our
+analysis gives $1.0 \le n \le 1.26$ (95 % C.L.) for $\Omega_b = 0.05$.",9609154v1
+1996-10-29,Anisotropies in the Cosmic Microwave Background: Theoretical Foundations,"The analysis of anisotropies in the cosmic microwave background (CMB) has
+become an extremely valuable tool for cosmology. We even have hopes that
+planned CMB anisotropy experiments may revolutionize cosmology. Together with
+determinations of the CMB spectrum, they represent the first cosmological
+precision measurements. This is illustrated in the talk by Anthony Lasenby. The
+value of CMB anisotropies lies to a big part in the simplicity of the
+theoretical analysis. Fluctuations in the CMB can be determined almost fully
+within linear cosmological perturbations theory and are not severely influenced
+by complicated nonlinear physics. In this contribution the different physical
+processes causing or influencing anisotropies in the CMB are discussed. The
+geometry perturbations at and after last scattering, the acoustic oscillations
+in the baryon-photon-plasma prior to recombination, and the diffusion damping
+during the process of recombination. The perturbations due to the fluctuating
+gravitational field, the so called Sachs-Wolfe contribution, is described in a
+very general form using the Weyl tensor of the perturbed geometry.",9610234v1
+1996-12-19,The Power Spectrum of Microwave Background Temperature Anisotropies Measured by the Tenerife Experiment,"We determine the slope of the power spectrum of the matter perturbations from
+the Tenerife observations of the cosmic background radiation temperature
+anisotropies. We compute the projected radiation anisotropy power spectrum
+measured by this experiment and study its dependence with respect to the slope
+of the temperature anisotropy spectrum on the sky. We show that Tenerife alone
+implies the upper bound on the spectral index of $m \le 3$. Stronger
+conclusions can not be reached due to the small data set. The method proposed
+can be applied to any small scale experiment. Sampling the same region of the
+skywith different window functions could probe the slope of the radiation
+anisotropy power spectrum at different scales and confirm the presence of
+Doppler peaks.",9612195v1
+1997-03-29,Fokker-Planck Models of Star Clusters with Anisotropic Velocity Distributions. III. Multi-Mass Clusters,"The evolution of globular clusters driven by two-body relaxation is
+investigated by means of numerical integration of the two-dimensional
+Fokker-Planck equation in energy--angular momentum space. The two- dimensional
+Fokker-Planck equation allows the development of velocity anisotropy. We
+include a spectrum of stellar masses in this paper. The radial anisotropy
+develops, that is, the radial velocity dispersion exceeds the tangential one,
+in the outer halo of multi-mass clusters as in single-mass clusters. However,
+the evolution of the velocity anisotropy depends significantly on the stellar
+mass in some cases. In fact the tangential velocity dispersion becomes dominant
+around the half-mass radius for massive components in clusters with a steep
+mass function. The development of this tangential anisotropy is closely related
+to the initial cooling of the massive components toward energy equipartition.
+Our simulation results indicate that multi-mass anisotropic King-Michie models
+are not always appropriate for describing the velocity anisotropy in globular
+clusters.",9703190v1
+1997-04-16,CMB Anisotropy Induced by Cosmic Strings on Angular Scales $>~ 15'$,"We have computed an estimate of the angular power spectrum of the Cosmic
+Microwave Background (CMB) induced by cosmic strings on angular scales $>~
+15'$, using a numerical simulation of a cosmic string network; and decomposed
+this pattern into scalar, vector, and tensor parts. We find no evidence for
+strong acoustic oscillations in the scalar anisotropy but rather a broad peak.
+The anisotropies from vector modes dominate except on very small angular scales
+while the tensor anisotropies are sub-dominant on all angular scales. The
+anisotropies generated after recombination are even more important than in
+adiabatic models. We expect that these qualitative features are robust to the
+varying of cosmological parameters, a study which has not yet been done.",9704160v1
+1997-09-18,Secondary gravitational anisotropies in open universes,"The applicability of the potential approximation in the case of open
+universes is tested. Great Attractor-like structures are considered in the
+test. Previous estimates of the Cosmic Microwave background anisotropies
+produced by these structures are analyzed and interpreted. The anisotropies
+corresponding to inhomogeneous ellipsoidal models are also computed. It is
+proved that, whatever the spatial symmetry may be, Great Attractor-like objects
+with extended cores (radius $\sim 10h^{-1}$),located at redshift $z=5.9$ in an
+open universe with density parameter $\Omega_{0}=0.2$, produce secondary
+gravitational anisotropies of the order of $10^{-5}$ on angular scales of a few
+degrees. This anisotropy appears to be an integrated effect along the photon
+geodesics. Its angular scale is much greater than that subtended by the Great
+Attractor itself. This is understood taking into account that the integrated
+effect is produced by the variations of the gravitational potential, which seem
+to be important in large regions subtending angular scales of various degrees.
+As a result of the large size of these regions, the spatial curvature of the
+universe becomes important and, consequently, significant errors ($\sim 30$ per
+cent) arise in estimations based on the potential approximation.",9709181v1
+1997-12-11,Effect of Void Network on CMB Anisotropy,"We study the effect of a void network on the CMB anisotropy in the
+Einstein-de Sitter background using Thompson &Vishniac's model. We consider
+comprehensively the Sacks-Wolfe effect, the Rees-Sciama effect and the
+gravitational lensing effect. Our analysis includes the model of primordial
+voids existing at recombination, which is realized in some inflationary models
+associated with a first-order phase transition. If there exist primordial voids
+whose comoving radius is larger than $\sim10h^{-1}$Mpc at recombination, not
+only the Sachs-Wolfe effect but also the Rees-Sciama effect is appreciable even
+for multipoles $l\lsim1000$ of the anisotropy spectrum. The gravitational
+lensing effect, on the other hand, slightly smoothes the primary anisotropy;
+quantitatively, our results for the void model are similar to the previous
+results for a CDM model. All the effects, together, would give some constraints
+on the configuration or origin of voids with high-resolution data of the CMB
+anisotropy.",9712153v2
+1998-02-09,A Vishniac type contribution to the polarisation of the CMBR?,"Radiation which has a quadrupole component of anisotropy, can get polarized
+by Thomson scattering from charged particles. In the cosmological context, the
+microwave background photons develop significant quadrupole anisotropy as they
+free stream away from the the epoch of standard recombination. Reionization in
+the post recombination era can provide free electrons to Thomson scatter the
+incident anisotropic $CMBR$ photons. We compute the resulting polarisation
+anisotropy on small (arc-minute) angular scales. We look for significant
+non-linear contributions, as in the case of Vishniac effect in temperature
+anisotropy, due to the coupling of small-scale electron density fluctuations,
+at the new last scattering surface, and the temperature quadrupole. We show
+that, while, in cold dark matter type models, this does not lead to very
+significant signals ($\sim 0.02 - 0.04 \mu K$), a larger small angular scale
+polarization anisotropy, ($\sim 0.1 - 0.5\mu K$), can result in isocurvature
+type models.",9802099v1
+1998-11-19,Contribution of Bright Extragalactic Radio Sources to Microwave Anisotropy,"We estimate the contribution of extragalactic radio sources to fluctuations
+in sky temperature over the range of frequencies (10-300 GHz) used for Cosmic
+Microwave Background (CMB) anisotropy measurements. CMB anisotropy observations
+at high resolution and low frequencies are especially sensitive to this
+foreground. We have compiled a catalog of 2207 bright radio sources, including
+758 sources with flux measurements at 90 GHz. We develop a method to
+extrapolate the source spectra and predict skymaps of extragalactic radio
+sources at instrument resolutions of 10 arcmin to 10 degrees FWHM. Our results
+indicate that the brightest sources will dominate microwave anisotropy for a
+wide range of resolutions and frequencies. Our skymaps predict the location and
+flux of the brightest radio sources at each frequency, making it
+straightforward to develop a template for masking the pixels containing them.
+This masking should be sufficient to protect high resolution CMB anisotropy
+observations from unacceptable radio source confusion.",9811311v1
+2000-04-03,Cosmic Ray Anisotropy Analysis with a Full-Sky Observatory,"A cosmic ray observatory with full-sky coverage can exploit standard
+anisotropy analysis methods that do not work if part of the celestial sphere is
+never seen. In particular, the distribution of arrival directions can be fully
+characterized by a list of spherical harmonic coefficients. The dipole vector
+and quadrupole tensor are of special interest, but the full set of harmonic
+coefficients constitutes the anisotropy fingerprint that may be needed to
+reveal the identity of the cosmic ray sources. The angular power spectrum is a
+coordinate-independent synopsis of that fingerprint. The true cosmic ray
+anisotropy can be measured despite non-uniformity in celestial exposure,
+provided the observatory is not blind to any region of the sky. This paper
+examines quantitatively how the accuracy of anisotropy measurement depends on
+the number of arrival directions in a data set.",0004016v1
+2001-03-30,Probing the Universe After Cosmological Recombination Through the Effect of Neutral Lithium on the Microwave Background Anisotropies,"I show that neutral lithium couples strongly to the cosmic microwave
+background (CMB) through its 6708A resonant transition after it recombines at
+z~500. At observed wavelengths of <335 micron, the CMB anisotropies are
+significantly altered since the optical depth for resonant scattering by
+neutral lithium is substantial, of order 0.5. The scattering would suppress the
+original anisotropies, but will generate strong new anisotropies in the CMB
+temperature and polarization on sub-degree scales (l>100). Observations at
+different wavelengths in this spectral regime can probe different thin slices
+of the early universe. The anisotropy noise contributed by continuum radiation
+from foreground far--infrared sources could be taken out by subtracting maps at
+slightly different wavelengths. Detection of the above effects can be used to
+study structure at z<500 and to constrain the primordial abundance and
+recombination history of lithium.",0103505v2
+2003-02-07,MAXIMA: Observations of CMB Anisotropy,"This document describes the Millimeter Anisotropy eXperiment IMaging Array
+(MAXIMA), a balloon-borne experiment measuring the temperature anisotropy of
+the Cosmic Microwave Background (CMB) on angular scales of 10 arcminutes to 5
+degrees. MAXIMA maps the CMB using 16 bolometric detectors observing in
+spectral bands centered at 150 GHz, 230 GHz, and 410 GHz, with 10 arcminute
+resolution at all frequencies. The combined receiver sensitivity to CMB
+anisotropy is 40 micro-K*(sec^0.5). During two flights with a total of 8.5
+hours of CMB observations, 300 square degrees of the sky were mapped. MAXIMA
+data are used to discriminate between cosmological models and to determine
+cosmological parameters; results are presented from the 1998 flight. The
+angular power spectrum derived from these data shows a narrow peak near l=200,
+and is consistent with inflationary Big Bang models. Cosmological parameters
+are estimated, including total density Omega(total)=0.9(-0.16,+0.18), baryon
+density Omega(b)h^2=0.033(+/-0.013), and power spectrum normalization
+C(10)=690(-125,+200) micro-K^2. The final chapter is a discussion CMB
+polarization anisotropy, including an overview of MAXIPOL, the polarization
+sensitive follow-up to MAXIMA.",0302159v1
+2003-06-17,CMB Anisotropies in the Presence of Extra Dimensions,"We discuss the effect of the time evolution of extra dimensions on CMB
+anisotropies and large-scale structure formation. We study the impact of scalar
+fields in a low-energy effective description of a general class of brane world
+models on the temperature anisotropy power spectrum. We show that when the
+coupling between these scalar fields and matter evolves over cosmological
+timescales, current observations of the CMB anisotropies can constrain
+primordial values of the fields in a manner complementary to local, late-time
+tests of gravity. We also present the effect of these fields on the
+polarization anisotropy spectra and the growth of large-scale structure,
+showing that future CMB observations will constrain theories of the Universe
+involving extra dimensions even further.",0306343v1
+2003-09-10,The CMB Quadrupole in a Polarized Light,"The low quadrupole of the cosmic microwave background (CMB), measured by COBE
+and confirmed by WMAP, has generated much discussion recently. We point out
+that the well-known correlation between temperature and polarization
+anisotropies of the CMB further constrains the low multipole anisotropy data.
+This correlation originates from the fact that the low-multipole polarization
+signal is sourced by the CMB quadrupole as seen by free electrons during the
+relatively recent cosmic history. Consequently, the large-angle temperature
+anisotropy data make restrictive predictions for the large-angle polarization
+anisotropy, which depend primarily on the optical depth for electron scattering
+after cosmological recombination, tau. We show that if current cosmological
+models for the generation of large angle anisotropy are correct and the
+COBE/WMAP data are not significantly contaminated by non-CMB signals, then the
+observed C_te amplitude on the largest scales is discrepant at the 99.8% level
+with the observed C_tt for the concordance LCDM model with tau=0.10. Using
+tau=0.17, the preferred WMAP model-independent value, the discrepancy is at the
+level of 98.5%.",0309281v2
+2004-08-10,Observation by an Air-Shower Array in Tibet of the Multi-TeV Cosmic-Ray Anisotropy due to Terrestrial Orbital Motion Around the Sun,"We report on the solar diurnal variation of the galactic cosmic-ray intensity
+observed by the Tibet III air shower array during the period from 1999 to 2003.
+In the higher-energy event samples (12 TeV and 6.2 TeV), the variations are
+fairly consistent with the Compton-Getting anisotropy due to the terrestrial
+orbital motion around the sun, while the variation in the lower-energy event
+sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an
+additional anisotropy superposed at the multi-TeV energies, e.g. the solar
+modulation effect. This is the highest-precision measurement of the
+Compton-Getting anisotropy ever made.",0408187v1
+2004-11-02,The Physics of CMBR Anisotropies,"The observed structures in the universe are thought to have arisen from
+gravitational instability acting on small fluctuations generated in the early
+universe. These spatial fluctuations are imprinted on the CMBR as angular
+anisotropies. The physics which connects initial fluctuations in the early
+universe to the observed anisotropies is fairly well understood, since for most
+part it involves linear perturbation theory. This makes CMBR anisotropies one
+of the cleanest probes of the initial fluctuations, various cosmological
+parameters governing their evolution and also the geometry of the universe. We
+review here in a fairly pedagogical manner the physics of the CMBR anisotropies
+and explain the role they play in probing cosmological parameters, especially
+in the light of the latest observations from the WMAP satellite.",0411049v1
+2005-05-09,Second-order gravitational effects of local inhomogeneities on CMB anisotropies in nonzero-Lambda flat cosmological models,"Nonlinear gravitational effects of large-scale inhomogeneities on Cosmic
+Microwave Background (CMB) anisotropies are studied. based on the relativistic
+second-order theory of perturbations in nonzero-Lambda flat cosmological
+models, which has been analytically derived by the present author, and on the
+second-order formula of CMB anisotropies derived by Mollerach and Matarrese. In
+this paper we derive the components of the CMB anisotropy power spectra in the
+range of l = 1 -22 which are caused by asymmetric local inhomogeneities on
+scales of 300 Mpc. Using our results it is found that there is a possibility to
+explain the small north-south asymmetry of CMB anisotropies which has recently
+been observed.",0505157v6
+2005-07-13,A closer look at the spectrum and small scale anisotropies of UHECRs,"We present results of numerical simulations of the propagation of ultra high
+energy cosmic rays (UHECRs) over cosmological distances, aimed at quantifying
+the statistical significance of the highest energy data on the spectrum and
+small scale anisotropies as detected by the AGASA experiment. We assess the
+significance of the lack of a GZK feature and its compatibility with the
+reported small scale anisotropies.
+  Assuming that UHECRs are protons from extragalactic sources, we find that the
+small scale anisotropies are incompatible with the reported spectrum at a
+probability level of $2 \times 10^{-5}$. Our analysis of the AGASA results
+shows the power of combining spectrum and small scale anisotropy data in future
+high statistics experiments, such as Auger.",0507324v1
+2006-01-13,The Anisotropy of Galactic Cosmic Rays as a Product of Stochastic Supernova Explosions,"We study the effect of the stochastic character of supernova explosions on
+the anisotropy of galactic cosmic rays below the knee. We conclude that if the
+bulk of cosmic rays are produced in supernova explosions the observed small and
+nearly energy independent amplitude of the anisotropy and its phase are to the
+large extent determined by the history of these explosions in the vicinity of
+the solar system, namely by the location and the age of the supernova remnants,
+within a few kpc, which give the highest contribution to the total intensity at
+the present epoch. Among the most important factors which result in the small
+magnitude and the energy independence of the anisotropy amplitude are the mixed
+primary mass composition, the effect of the Single Source and the Galactic
+Halo. Special attention is given to the phase of the anisotropy. It is shown
+that the excessive flux from the Outer Galaxy can be due to the location of the
+solar system at the inner edge of the Orion Arm which has the enhanced density
+and rate of supernova explosions.",0601290v1
+2006-09-13,Imprint of spatial curvature on inflation power spectrum,"If the universe had a large curvature before inflation there is a deviation
+from the scale invariant perturbations of the inflaton at the beginning of
+inflation. This may have some effect on the CMB anisotropy at large angular
+scales. We calculate the density perturbations for both open and closed
+universe cases using the Bunch-Davies vacuum condition on the initial state. We
+use our power spectrum to calculate the temperature anisotropy spectrum and
+compare the results with the WMAP three year data. We find that our power
+spectrum gives a lower quadrupole anisotropy when $\Omega-1 >0$, but matches
+the temperature anisotropy calculated from the standard Ratra-Peebles power
+spectrum at large $l$. The determination of spatial curvature from temperature
+anisotropy data is not much affected by the different power spectra which arise
+from the choice of different boundary conditions for the inflaton perturbation.",0609349v4
+2006-10-05,Anisotropy of Magnetohydrodynamic Turbulence and Polarization of the Spectral Lines of Molecules,"The anisotropy of velocities in MHD turbulence is demonstrated explicitly by
+calculating the velocity gradients as a function of direction in representative
+simulations of decaying turbulence. It follows that the optical depths of
+spectral lines are anisotropic when there is MHD turbulence, and that this
+anisotropy influences the polarization characteristics of the emergent
+radiation. We calculate the linear polarization that results for the microwave
+lines of the CO molecule in star-forming gas and show that it is comparable to
+the polarization that is observed. This and our earlier result--that the
+anisotropy of MHD turbulence may be the cause for the absence of the Zeeman
+$\pi $-components in the spectra of OH mainline masers--are the first
+demonstrations of the occurrence of anisotropy in the optical depths caused by
+MHD turbulence. A non-local approximation is developed for the radiative
+transfer and the results are compared with those from a local (LVG)
+approximation.",0610144v1
+2006-10-23,Anisotropy and Corotation of Galactic Cosmic Rays,"The intensity of Galactic cosmic rays is nearly isotropic because of the
+influence of magnetic fields in the Milky Way. Here, we present two-dimensional
+high-precision anisotropy measurement for energies from a few to several
+hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air
+Shower Arrays. Besides revealing finer details of the known anisotropies, a new
+component of Galactic cosmic ray anisotropy in sidereal time is uncovered
+around the Cygnus region direction. For cosmic-ray energies up to a few hundred
+TeV, all components of anisotropies fade away, showing a corotation of Galactic
+cosmic rays with the local Galactic magnetic environment. These results have
+broad implications for a comprehensive understanding of cosmic rays,
+supernovae, magnetic fields, and heliospheric and Galactic dynamic
+environments.",0610671v1
+2007-01-29,The Signature of Patchy Reionization in the Polarization Anisotropy of the CMB,"The inhomogeneous ionization state of the universe when the first sources of
+ionizing radiation appeared should lead to anisotropies in the polarization of
+the cosmic microwave background. We use cosmological simulations of the process
+by which the first sources ionized the intergalactic medium to study the
+induced polarization anisotropies. We find that the polarization anisotropies
+have rms of order ~0.01 \mu K, and local peak values of ~0.1 \mu K, smaller
+than those due to gravitational lensing on small scales. The polarization
+direction is highly coherent over degree scales. This directional coherence is
+not expected from either primary anisotropy or gravitational lensing effects,
+making the largest signals due to inhomogeneous ionization relatively easy to
+isolate, should experiments achieve the necessary very low noise levels.",0701784v1
+2007-03-20,CMB Spectral Distortions from the Scattering of Temperature Anisotropies,"Thomson scattering of CMBR temperature anisotropies will cause the spectrum
+of the CMBR to differ from blackbody even when one resolves all anisotropies. A
+formalism for computing the anisotropic and inhomogeneous spectral distortions
+of intensity and polarization is derived in terms of Lorentz invariant central
+moments of the temperature distribution. The formalism is non-perturbative,
+requiring neither small anisotropies nor small metric or matter
+inhomogeneities; but it does assume cold electrons. The low order moments are
+not coupled to the higher order moments allowing one to truncate the equations
+without any loss of accuracy. This formalism is applied to a standard
+Lambda-CDM cosmology after reionization where the temperature anisotropies are
+dominated by the Doppler effect for the bulk motion of the gas with respect to
+the CMBR frame. The resultant spectral distortion is parameterized by u ~ 3e-8,
+where in this case u is observationally degenerate with the Sunyaev-Zel'dovich
+(SZ) y parameter. In comparison the expected thermal SZ y-distortion from the
+hot IGM is expected to be >30 times larger. However at z >5 the effect
+described here would have been the dominant source of spectral distortions. The
+effect could be much larger in non-standard cosmologies.",0703541v1
+1997-01-16,Exchange Anisotropy in Epitaxial and Polycrystalline NiO/NiFe Bilayers,"(001) oriented NiO/NiFe bilayers were grown on single crystal MgO (001)
+substrates by ion beam sputtering in order to determine the effect that the
+crystalline orientation of the NiO antiferromagnetic layer has on the
+magnetization curve of the NiFe ferromagnetic layer. Simple models predict no
+exchange anisotropy for the (001)-oriented surface, which in its bulk
+termination is magnetically compensated. Nonetheless exchange anisotropy is
+present in the epitaxial films, although it is approximately half as large as
+in polycrystalline films that were grown simultaneously. Experiments show that
+differences in exchange field and coercivity between polycrystalline and
+epitaxial NiFe/NiO bilayers couples arise due to variations in induced surface
+anisotropy and not from differences in the degree of compensation of the
+terminating NiO plane. Implications of these observations for models of induced
+exchange anisotropy in NiO/NiFe bilayer couples will be discussed.",9701115v1
+1998-10-15,Ordering in magnetic films with surface anisotropy,"Effects of the surface exchange anisotropy on ordering of ferromagnetic films
+are studied for the exactly solvable classical spin-vector model with D \to
+\infty components. For small surface anisotropy \eta'_s << 1 (defined relative
+to the exchange interaction), the shift of T_c in a film consisting of N >> 1
+layers behaves as T_c^{\rm bulk} - T_c(N) ~ (1/N)\ln(1/\eta'_s) in three
+dimensions. The finite-size-scaling limit T_c^{\rm bulk} - T_c(N) \propto
+1/(\eta'^{1/2}N^2), which is realized for the model with a bulk anisotropy
+\eta' << 1 in the range N\eta'^{1/2} >~ 1, never appears for the model with the
+pure surface anisotropy. Here for N\exp(-1/\eta'_s) >~ 1 in three dimensions,
+film orders at a temperature above T_c^{\rm bulk} (the surface phase
+transition). In the semi-infinite geometry, the surface phase transition occurs
+for whatever small values of \eta'_s (i.e., the special phase transition
+corresponds to T_c^{\rm bulk}) in dimensions three and lower.",9810182v1
+1999-03-02,Triangular anisotropies in Driven Diffusive Systems: reconciliation of Up and Down,"Deterministic coarse-grained descriptions of driven diffusive systems (DDS)
+have been hampered by apparent inconsistencies with kinetic Ising models of
+DDS. In the evolution towards the driven steady-state, ``triangular''
+anisotropies in the two systems point in opposite directions with respect to
+the drive field. We show that this is non-universal behavior in the sense that
+the triangular anisotropy ``flips'' with local modifications of the Ising
+interactions. The sign and magnitude of the triangular anisotropy also vary
+with temperature. We have also flipped the anisotropy of coarse-grained models,
+though not yet at the latest stages of evolution. Our results illustrate the
+comparison of deterministic coarse-grained and stochastic Ising DDS studies to
+identify universal phenomena in driven systems. Coarse-grained systems are
+particularly attractive in terms of analysis and computational efficiency.",9903049v1
+1999-12-16,Viscous fingering in liquid crystals: Anisotropy and morphological transitions,"We show that a minimal model for viscous fingering with a nematic liquid
+crystal in which anisotropy is considered to enter through two different
+viscosities in two perpendicular directions can be mapped to a two-fold
+anisotropy in the surface tension. We numerically integrate the dynamics of the
+resulting problem with the phase-field approach to find and characterize a
+transition between tip-splitting and side-branching as a function of both
+anisotropy and dimensionless surface tension. This anisotropy dependence could
+explain the experimentally observed (reentrant) transition as temperature and
+applied pressure are varied. Our observations are also consistent with previous
+experimental evidence in viscous fingering within an etched cell and
+simulations of solidification.",9912312v1
+2000-02-24,High Frequency EPR Spectra of [Fe8O2(OH)12(tacn)6]Br8. A Critical Appraisal of the Barrier for the Reorientation of the Magnetization in Single Molecule Magnets,"A detailed multifrequency high field - high frequency EPR (95-285 GHz) study
+has been performed on the single-molecule magnet of formula
+  [Fe8O2(OH)12(tacn)6]Br8 9H2O, where tacn=1,4,7-triazacyclononane.
+Polycrystalline powder spectra have allowed estimating the zero field splitting
+parameters up to the fourth order terms.
+  The single crystal spectra have provided the principal directions of the
+magnetic anisotropy of the cluster. These results have been compared to an
+evaluation of the intra-cluster dipolar contribution to the magnetic
+anisotropy, suggesting that single ion anisotropy is mainly contributing to the
+magnetic anisotropy.
+  The role of the transverse magnetic anisotropy in determining the height of
+the barrier for the reversal of the magnetization is also discussed.",0002386v1
+2000-05-26,Finite-temperature ordering in two-dimensional magnets,"We study the two dimensional quantum Heisenberg antiferromagnet on the square
+lattice with easy-axis exchange anisotropy. By the semiclassical method called
+pure-quantum self-consistent harmonic approximation we analyse several
+thermodynamic quantities and investigate the existence of a finite temperature
+transition, possibly describing the low-temperature critical behaviour
+experimentally observed in many layered real compounds.
+  We find that an Ising-like transition characterizes the model even when the
+anisotropy is of the order of $10^{-2}J$ ($J$ being the intra-layer exchange
+integral), as in most experimental situations. On the other hand, typical
+features of the isotropic Heisenberg model are observed for both values of
+anisotropy considered, one in the {\it quasi}-isotropic limit and the other in
+a more markedly easy-axis region.
+  The good agreement found between our theoretical results and the experimental
+data relative to the real compound Rb$_2$MnF$_4$ shows that the insertion of
+the easy-axis exchange anisotropy, with quantum effects properly taken into
+account, provides a quantitative description and explanation of the
+experimental data, thus allowing to recognize in such anisotropy the main agent
+for the observed onset of finite temperature long-range order.",0005464v1
+2000-12-29,Hysteresis and Avalanches in the Random Anisotropy Ising Model,"The behaviour of the Random Anisotropy Ising model at T=0 under local
+relaxation dynamics is studied. The model includes a dominant ferromagnetic
+interaction and assumes an infinite anisotropy at each site along local
+anisotropy axes which are randomly aligned. Two different random distributions
+of anisotropy axes have been studied. Both are characterized by a parameter
+that allows control of the degree of disorder in the system. By using numerical
+simulations we analyze the hysteresis loop properties and characterize the
+statistical distribution of avalanches occuring during the metastable evolution
+of the system driven by an external field. A disorder-induced critical point is
+found in which the hysteresis loop changes from displaying a typical
+ferromagnetic magnetization jump to a rather smooth loop exhibiting only tiny
+avalanches. The critical point is characterized by a set of critical exponents,
+which are consistent with the universal values proposed from the study of other
+simpler models.",0012508v1
+2001-08-31,Inversion Phenomena of the Anisotropies of the Hamiltonian and the Wave-Function in the Distorted Diamond Type Spin Chain,"We investigate the ground-sate phase diagram of the XXZ version of the S=1/2
+distorted diamond chain by use of the degenerate perturbation theory near the
+truncation point. In case of the XY-like interaction anisotropy, the phase
+diagram consists of the Neel phase and the spin-fluid phase. For the Ising-like
+interaction anisotropy case, it consists of three phases: the ferrimagnetic
+phase, the Neel phase and the spin-fluid phase. The magnetization in the
+ferrimagnetic phase is 1/3 of the saturation magnetization. The remarkable
+nature of the phase diagram is the existence of the Neel phase, although the
+interaction anisotropy is XY-like. And also, the spin-fluid phase appears in
+spite of the Ising-like interaction anisotropy. We call these regions
+""inversion regions"".",0108528v1
+2002-01-08,Many-body Green's function theory for thin ferromagnetic films: exact treatment of the single-ion anisotropy,"A theory for the magnetization of ferromagnetic films is formulated within
+the framework of many-body Green's funtion theory which considers all
+components of the magnetization. The model Hamiltonian includes a Heisenberg
+term, an external field, a second- and fourth-order uniaxial single-ion
+anisotropy, and the magnetic dipole-dipole coupling. The single-ion anisotropy
+terms can be treated exactly by introducing higher-order Green's functions and
+subsequently taking advantage of relations between products of spin operators
+which leads to an automatic closure of the hierarchy of the equations of motion
+for the Green's functions with respect to the anisotropy terms. This is an
+improvement on the method of our previous work, which treated the corresponding
+terms only approximately by decoupling them at the level of the lowest-order
+Green's functions. RPA-like approximations are used to decouple the exchange
+terms in both the low-order and higher-order Green's functions. As a first
+numerical example we apply the theory to a monolayer for spin S=1 in order to
+demonstrate the superiority of the present treatment of the anisotropy terms
+over the previous approximate decouplings.",0201097v1
+2002-04-09,In-plane anisotropy on the transport properties in the modulated Bi_2O_2-based conductors Bi-2212 and Bi-Sr-Co-O,"We investigated the in-plane anisotropy on the resistivity and thermopower of
+the Bi_2Sr_2CaCu_2O_{8+\delta} (Bi-2212) and Bi-Sr-Co-O (BiCo) single crystals.
+In Bi-2212, the b-axis resistivity is higher than the a-axis resistivity, and
+is expressed as a sum of the a-axis resistivity and an additional residual
+resistivity. A downward deviation due to pseudogap is observed below a
+characteristic temperature T^*, which is isotropic in the form of conductivity.
+These results suggest that the modulation structure along the b-axis works as
+an anisotropic scattering center, but does not affect the pseudogap formation.
+On the other hand, the anisotropy of the resistivity and the thermopower in
+Pb-doped BiCo is substantial, probably owing to the misfit structure between
+the hexagonal CoO_2 layer and the rock salt Bi_2O_2 layer. However, the
+anisotropy in the resistivity in Pb-free BiCo is very small, suggesting that
+the in-plane anisotropy is averaged by the modulation structure, whose
+direction is tilted by 45 deg from the a- and b-axes.",0204187v1
+2002-07-06,Square-lattice s=1/2 XY model and the Jordan-Wigner fermions: The ground-state and thermodynamic properties,"Using the 2D Jordan-Wigner transformation we reformulate the square-lattice
+s=1/2 XY (XZ) model in terms of noninteracting spinless fermions and examine
+the ground-state and thermodynamic properties of this spin system. We consider
+the model with two types of anisotropy: the spatial anisotropy interpolating
+between 2D and 1D lattices and the anisotropy of the exchange interaction
+interpolating between isotropic XY and Ising interactions. We compare the
+obtained (approximate) results with exact ones (1D limit, square-lattice Ising
+model) and other approximate ones (linear spin-wave theory and exact
+diagonalization data for finite lattices of up to N=36 sites supplemented by
+finite-size scaling). We discuss the ground-state and thermodynamic properties
+in dependence on the spatial and exchange interaction anisotropies. We pay
+special attention to the quantum phase transition driven by the exchange
+interaction anisotropy as well as to the appearance/disappearance of the
+zero-temperature magnetization in the quasi-1D limit.",0207179v1
+2002-08-16,In-plane dipole coupling anisotropy of a square ferromagnetic Heisenberg monolayer,"In this study we calculate the dipole-coupling-induced quartic in-plane
+anisotropy of a square ferromagnetic Heisenberg monolayer. This anisotropy
+increases with an increasing temperature, reaching its maximum value close to
+the Curie temperature of the system. At T=0 the system is isotropic, besides a
+small remaining anisotropy due to the zero-point motion of quantum mechanical
+spins. The reason for the dipole-coupling-induced anisotropy is the disturbance
+of the square spin lattice due to thermal fluctuations ('order-by-disorder'
+effect). For usual ferromagnets its strength is small as compared to other
+anisotropic contributions, and decreases by application of an external magnetic
+field. The results are obtained from a Heisenberg Hamiltonian by application of
+a mean field approach for a spin cluster, as well as from a many-body Green's
+function theory within the Tyablikov-decoupling (RPA).",0208324v1
+2002-12-20,"Temperature Dependent Magnetic Anisotropy in (Ga,Ma)As Layers","It is demonstrated by SQUID magnetization measurements that (Ga,Mn)As films
+can exhibit rich characteristics of magnetic anisotropy depending not only to
+the epitaxial strain but being strongly influenced by the hole and Mn
+concentration, and temperature. This behavior reflects the spin anisotropy of
+the valence subbands and corroborates predictions of the mean field Zener model
+of the carrier mediated ferromagnetism in III-V diluted magnetic semiconductors
+with Mn. At the same time the existence of in-plane uniaxial anisotropy with
+[110] the easy axis is evidenced. This is related to the top/bottom symmetry
+breaking, resulting in the lowering of point symmetry of (Ga,Mn)As to the
+C_{2v} symmetry group. The latter mechanism coexists with the hole-induced
+cubic anisotropy, but takes over close to T_C.",0212511v2
+2003-06-23,Anisotropic magnetoresistive and magnetic properties of La_{0.5}Sr_{0.5}CoO_{3-δ} film,"The magnetic and transport properties of La_{0.5}Sr_{0.5}CoO_{3-\delta} film
+grown on a LaAlO_3 substrate by pulsed-laser deposition are studied. The
+properties are found to be influenced by the magnetic anisotropy and
+inhomogeneity. Magnetoresistance anisotropy is determined by the shape
+anisotropy of the magnetization and the strain-induced magnetic anisotropy due
+to the film-substrate lattice interaction. Indications of the
+temperature-driven spin reorientation transition from an out-of plane orderded
+state at low temperatures to an in-plane ordered state at high temperatures as
+a result of competition between the mentioned sources of magnetic anisotropy
+are found.",0306565v1
+2003-10-29,Magnetic nanoparticles as many-spin systems,"We present a review of recent advances in the study of many-body effects in
+magnetic nanoparticles. Considering classical spins on a lattice coupled by the
+exchange interaction in the presence of the bulk and surface anisotropy, we
+investigate the effects of finite size, free boundaries, and surface anisotropy
+on the average and local magnetization for zero and finite temperatures and
+magnetic fields. Superparamagnetism of magnetic particles necessitates
+introducing two different, induced and intrinsic, magnetizations. We check the
+validity of the much used relation between them within different theoretical
+models. We show that the competition between the exchange and surface
+anisotropy leads to spin canting dependent on the orientation of the average
+magnetization with respect to the crystallographic axes and thus to a
+second-order effective anisotropy of the particle. We have also investigated
+the switching mechanism of the magnetization upon varying the surface
+anisotropy constant. Some cases of more realistic particles are also dealt
+with.",0310694v1
+2004-03-08,Reversible magnetization measurement of the anisotropy of the London penetration depth in MgB2 single crystals,"We have studied the anisotropy of the London penetration depth, which was
+obtained from reversible magnetization measurements with the magnetic field
+both parallel and perpendicular to the c-axis. The anisotropy of the London
+penetration depth has a smaller magnitude than the anisotropy of the upper
+critical field and increases with temperature while that of the upper critical
+field decreases as reported earlier. This behavior is in sharp contrast with
+the behaviors of superconductors with one superconducting energy gap. The
+temperature dependence of the anisotropies of the London penetration depth and
+of the upper critical field can be well explained within the theory of two-gap
+superconductivity in MgB2.",0403198v1
+2004-07-29,Anisotropy in Ferromagnetic Nanoparticles: Level-to-Level Fluctuations of a Collective Effect,"We calculate the mesoscopic fluctuations of the magnetic anisotropy of
+ferromagnetic nanoparticles. A microscopic spin-orbit Hamiltonian considered as
+a perturbation of the much stronger exchange interaction first yields an
+explicit expression for the anisotropy tensor. Then, assuming a simple random
+matrix model for the spin-orbit coupling allows us to describe the fluctuation
+of such a tensor. In the case of uniaxial anisotropy, we calculate the
+distribution of the anisotropy constant for a given number of electrons, and
+its variation upon increasing this number by one. The magnitude of the latter
+is sufficient to account for the experimental data.",0407771v2
+2004-09-13,Thermal and magnetic properties of spin-1 magnetic chain compounds with large single-ion and in-plane anisotropies,"The thermal and magnetic properties of spin-1 magnetic chain compounds with
+large single-ion and in-plane anisotropies are investigated via the integrable
+su(3) model in terms of the quantum transfer matrix method and the recently
+developed high temperature expansion method for exactly solved models. It is
+shown that large single-ion anisotropy may result in a singlet gapped phase in
+the spin-1 chain which is significantly different from the standard Haldane
+phase. A large in-plane anisotropy may destroy the gapped phase. On the other
+hand, in the vicinity of the critical point a weak in-plane anisotropy leads to
+a different phase transition than the Pokrovsky-Talapov transition. The
+magnetic susceptibility, specific heat and magnetization evaluated from the
+free energy are in excellent agreement with the experimental data for the
+compounds NiC_2H_8N_2)_2Ni(CN)_4 and Ni(C_{10}H_8N_2)_2Ni(CN)_4.H_2O.",0409310v1
+2005-02-28,Magnetization of nanomagnet assemblies: Effects of anisotropy and dipolar interactions,"We investigate the effect of anisotropy and weak dipolar interactions on the
+magnetization of an assembly of nanoparticles with distributed magnetic
+moments, i.e., assembly of magnetic nanoparticles in the one-spin
+approximation, with textured or random anisotropy.
+  The magnetization of a free particle is obtained either by a numerical
+calculation of the partition function or analytically in the low and high field
+regimes, using perturbation theory and the steepest-descent approximation,
+respectively. The magnetization of an interacting assembly is computed
+analytically in the range of low and high field, and numerically using the
+Monte Carlo technique.
+  Approximate analytical expressions for the assembly magnetization are
+provided which take account of the dipolar interactions, temperature, magnetic
+field, and anisotropy. The effect of anisotropy and dipolar interactions are
+discussed and the deviations from the Langevin law they entail are
+investigated, and illustrated for realistic assemblies with the lognormal
+moment distribution.",0502660v2
+2005-04-20,The loss of anisotropy in MgB2 with Sc substitution and its relationship with the critical temperature,"The electrical conductivity anisotropy of the sigma-bands is calculated for
+the (Mg,Sc)B2 system using a virtual crystal model. Our results reveal that
+anisotropy drops with relatively little scandium content (< 30%); this
+behaviour coincides with the lowering of Tc and the reduction of the Kohn
+anomaly. This anisotropy loss is also found in the Al and C doped systems. In
+this work it is argued that the anisotropy, or 2D character, of the sigma-bands
+is an important parameter for the understanding of the high Tc found in MgB2.",0504495v2
+2005-07-18,Single-ion anisotropy in the gadolinium pyrochlores studied by an electron paramagnetic resonance,"The electron paramagnetic resonance is used to measure the single-ion
+anisotropy of Gd3+ ions in the pyrochlore structure of (Y{1-x}Gdx)2Ti2O7. A
+rather strong easy-plane type anisotropy is found. The anisotropy constant D is
+comparable to the exchange integral J in the prototype Gd2Ti2O7, D~0.75J and
+exceeds the dipolar energy scale. Physical implications of an easy-plane
+anisotropy for a pyrochlore antiferromagnet are considered. We calculate the
+magnetization curves at T=0 and discuss phase transitions in magnetic field.",0507413v1
+2006-01-03,Ginzburg-Landau theory of crystalline anisotropy for bcc-liquid interfaces,"The weak anisotropy of the interfacial free-energy $\gamma$ is a crucial
+parameter influencing dendritic crystal growth morphologies in systems with
+atomically rough solid-liquid interfaces. The physical origin and quantitative
+prediction of this anisotropy are investigated for body-centered-cubic (bcc)
+forming systems using a Ginzburg-Landau theory where the order parameters are
+the amplitudes of density waves corresponding to principal reciprocal lattice
+vectors. We find that this theory predicts the correct sign,
+$\gamma_{100}>\gamma_{110}$, and magnitude, $(\gamma_{100}-\gamma_{110}) /
+(\gamma_{100}+\gamma_{110})\approx 1%$, of this anisotropy in good agreement
+with the results of MD simulations for Fe. The results show that the
+directional dependence of the rate of spatial decay of solid density waves into
+the liquid, imposed by the crystal structure, is a main determinant of
+anisotropy. This directional dependence is validated by MD computations of
+density wave profiles for different reciprocal lattice vectors for $\{110\}$
+crystal faces. Our results are contrasted with the prediction of the reverse
+ordering $\gamma_{100}<\gamma_{110}$ from an earlier formulation of
+Ginzburg-Landau theory [Shih \emph{et al.}, Phys. Rev. A {\bf 35}, 2611
+(1987)].",0601057v2
+2006-04-05,Critical behavior of the random-anisotropy model in the strong-anisotropy limit,"We investigate the nature of the critical behavior of the random-anisotropy
+Heisenberg model (RAM), which describes a magnetic system with random uniaxial
+single-site anisotropy, such as some amorphous alloys of rare earths and
+transition metals. In particular, we consider the strong-anisotropy limit
+(SRAM), in which the Hamiltonian can be rewritten as the one of an Ising
+spin-glass model with correlated bond disorder. We perform Monte Carlo
+simulations of the SRAM on simple cubic L^3 lattices, up to L=30, measuring
+correlation functions of the replica-replica overlap, which is the order
+parameter at a glass transition. The corresponding results show critical
+behavior and finite-size scaling. They provide evidence of a finite-temperature
+continuous transition with critical exponents $\eta_o=-0.24(4)$ and
+$\nu_o=2.4(6)$. These results are close to the corresponding estimates that
+have been obtained in the usual Ising spin-glass model with uncorrelated bond
+disorder, suggesting that the two models belong to the same universality class.
+We also determine the leading correction-to-scaling exponent finding $\omega =
+1.0(4)$.",0604124v2
+2006-05-07,Giant magnetic anisotropy at nanoscale: overcoming the superparamagnetic limit,"It has been recently observed for palladium and gold nanoparticles, that the
+magnetic moment at constant applied field does not change with temperature over
+the range comprised between 5 and 300 K. These samples with size smaller than
+2.5 nm exhibit remanence up to room temperature. The permanent magnetism for so
+small samples up to so high temperatures has been explained as due to blocking
+of local magnetic moment by giant magnetic anisotropies. In this report we
+show, by analysing the anisotropy of thiol capped gold films, that the orbital
+momentum induced at the surface conduction electrons is crucial to understand
+the observed giant anisotropy. The orbital motion is driven by localised charge
+and/or spin through spin orbit interaction, that reaches extremely high values
+at the surfaces. The induced orbital moment gives rise to an effective field of
+the order of 103 T that is responsible of the giant anisotropy.",0605171v1
+2006-06-30,Anisotropic Aerogels for Studying Superfluid $^3$He,"It may be possible to stabilize new superfluid phases of $^{3}$He with
+anisotropic silica aerogels. We discuss two methods that introduce anisotropy
+in the aerogel on length scales relevant to superfluid $^{3}$He. First,
+anisotropy can be induced with uniaxial strain. A second method generates
+anisotropy during the growth and drying stages. We have grown cylindrical
+$\sim$98% aerogels with anisotropy indicated by preferential radial shrinkage
+after supercritical drying and find that this shrinkage correlates with small
+angle x-ray scattering (SAXS). The growth-induced anisotropy was found to be
+$\sim90^\circ$ out of phase relative to that induced by strain. This has
+implications for the possible stabilization of superfluid phases with specific
+symmetry.",0606784v2
+2006-07-18,Magnetic properties of Fe/Dy multilayers: a Monte Carlo investigation,"We investigate the magnetic properties of a Heisenberg ferrimagnetic
+multilayer by using Monte Carlo simulations. The aim of this work is to study
+the local structural anisotropy model which is a possible origin of the
+perpendicular magnetic anisotropy in transition metal/rare earth amorphous
+multilayers. We have considered a face centered cubic lattice where each site
+is occupied by a classical Heisenberg spin. We have introduced in our model of
+amorphous multilayers a small fraction of crystallized Fe-Dy nanoclusters with
+a mean anisotropy axis along the deposition direction. We show that a
+competition in the energy terms takes place between the mean uniaxial
+anisotropy of the Dy atoms in the nanoclusters and the random anisotropy of the
+Dy atoms in the matrix.",0607437v1
+2006-09-23,Effects of spin non-collinearities in magnetic nanoparticles,"In a many-spin approach that takes account of the internal structure,
+microscopic interactions and single-site anisotropies, we investigate the
+effect of spin non-collinearities induced by the boundary and surface
+anisotropy on the behaviour of individual magnetic nanoparticles.
+  Through analytical and numerical calculations, we show that there are mainly
+two regimes separated by some critical value of the surface anisotropy constant
+$K_s$ which controls the intensity of spin non-collinearities: i) the so called
+Stoner-Wohlfarth or N\'eel-Brown regime of a macrospin undergoing a coherent
+switching, ii) the many-spin regime where the strong spin non-collinearities
+invalidate the coherent mechanism, and where the particle's magnetic state and
+switching mechanisms can no longer be modeled by a macrospin.
+  For small-to-intermediate values of $K_s$, and within two models of surface
+anisotropy (transverse and N\'eel), the behaviour of the nanoparticle can be
+modeled by that of a macrospin with an effective potential energy containing a
+uniaxial and cubic anisotropy terms. This effective spin model provides a
+crossover between the two regimes.",0609606v1
+2006-10-18,A new type of temperature driven reorientation transition in magnetic thin films,"We present a new type of temperature driven spin reorientation transition
+(SRT) in thin films. It can occur when the lattice and the shape anisotropy
+favor different easy directions of the magnetization. Due to different
+temperature dependencies of the two contributions the effective anisotropy may
+change its sign and thus the direction of the magnetization as a function of
+temperature may change. Contrary to the well-known reorientation transition
+caused by competing surface and bulk anisotropy contributions the reorientation
+that we discuss is also found in film systems with a uniform lattice
+anisotropy. The results of our theoretical model study may have experimental
+relevance for film systems with positive lattice anisotropy, as e.g. thin iron
+films grown on copper.",0610504v1
+2006-10-27,Optical response of high-$T_c$ cuprates: possible role of scattering rate saturation and in-plane anisotropy,"We present a generalized Drude analysis of the in-plane optical conductivity
+$\sigma_{ab}$($T$,$\omega$) in cuprates taking into account the effects of
+in-plane anisotropy. A simple ansatz for the scattering rate
+$\Gamma$($T$,$\omega$), that includes anisotropy, a quadratic frequency
+dependence and saturation at the Mott-Ioffe-Regel limit, is able to reproduce
+recent normal state data on an optimally doped cuprate over a wide frequency
+range. We highlight the potential importance of including anisotropy in the
+full expression for $\sigma_{ab}$($T$,$\omega$) and challenge previous
+determinations of $\Gamma$($\omega$) in which anisotropy was neglected and
+$\Gamma$($\omega$) was indicated to be strictly linear in frequency over a wide
+frequency range. Possible implications of our findings for understanding
+thermodynamic properties and self-energy effects in high-$T_c$ cuprates will
+also be discussed.",0610763v1
+2006-11-06,"Transport Characterization of the Magnetic Anisotropy of (Ga,Mn)As","The rich magnetic anisotropy of compressively strained (Ga,Mn)As has
+attracted great interest recently. Here we discuss a sensitive method to
+visualize and quantify the individual components of the magnetic anisotropy
+using transport. A set of high resolution transport measurements is compiled
+into color coded resistance polar plots, which constitute a fingerprint of the
+symmetry components of the anisotropy. As a demonstration of the sensitivity of
+the method, we show that these typically reveal the presence of both the [-110]
+and the [010] uniaxial magnetic anisotropy component in (Ga,Mn)As layers, even
+when most other techniques reveal only one of these components.",0611156v1
+2007-01-25,Theory of the in-plane anisotropy of magnetic excitations in YBa_{2}Cu_{3}O_{6+y},"A pronounced xy-anisotropy was observed in recent neutron scattering
+experiments for magnetic excitations in untwinned YBa_{2}Cu_{3}O_{6+y} (YBCO).
+The small anisotropy of the bare band structure due to the orthorhombic crystal
+symmetry seems to be enhanced by correlation effects. A natural possibility is
+that the system is close to a Pomeranchuk instability associated with a d-wave
+Fermi surface deformation (dFSD). We investigate this possibility in the
+bilayer t-J model within a self-consistent slave-boson mean-field theory. We
+show that the dFSD correlations drive a pronounced xy-anisotropy of magnetic
+excitations at low doping and at relatively high temperatures, providing a
+scenario for the observed xy-anisotropy in optimally doped as well as
+underdoped YBCO, including the pseudogap phase.",0701625v1
+1995-11-27,Statistics of the Microwave Background Anisotropies Caused by Cosmological Perturbations of Quantum-Mechanical Origin,"The genuine quantum gravity effects can already be around us. It is likely
+that the observed large-angular-scale anisotropies in the microwave background
+radiation are induced by cosmological perturbations of quantum-mechanical
+origin. Such perturbations are placed in squeezed vacuum quantum states and,
+hence, are characterized by large variances of their amplitude. The statistical
+properties of the anisotropies should reflect the underlying statistics of the
+squeezed vacuum quantum states. In this paper, the theoretical variances for
+the temperature angular correlation function are described in detail. It is
+shown that they are indeed large and must be present in the observational data,
+if the anisotropies are truly caused by the perturbations of quantum-mechanical
+origin. Unfortunately, these large theoretical statistical uncertainties will
+make the extraction of cosmological information from the measured anisotropies
+a much more difficult problem than we wanted it to be. This contribution to the
+Proceedings is largely based on references~[42,8]. The Appendix contains an
+analysis of the ``standard'' inflationary formula for density perturbations.",9511074v1
+2000-11-29,Anisotropy dissipation in brane-world inflation,"We examine the behavior of an anisotropic brane-world in the presence of
+inflationary scalar fields. We show that, contrary to naive expectations, a
+large anisotropy does not adversely affect inflation. On the contrary, a large
+initial anisotropy introduces more damping into the scalar field equation of
+motion, resulting in greater inflation. The rapid decay of anisotropy in the
+brane-world significantly increases the class of initial conditions from which
+the observed universe could have originated. This generalizes a similar result
+in general relativity. A unique feature of Bianchi I brane-world cosmology
+appears to be that for scalar fields with a large kinetic term the initial
+expansion of the universe is quasi-isotropic. The universe grows more
+anisotropic during an intermediate transient regime until anisotropy finally
+disappears during inflationary expansion.",0011105v3
+2006-09-16,Bounds on the basic physical parameters for anisotropic compact general relativistic objects,"We derive upper and lower limits for the basic physical parameters
+(mass-radius ratio, anisotropy, redshift and total energy) for arbitrary
+anisotropic general relativistic matter distributions in the presence of a
+cosmological constant. The values of these quantities are strongly dependent on
+the value of the anisotropy parameter (the difference between the tangential
+and radial pressure) at the surface of the star. In the presence of the
+cosmological constant, a minimum mass configuration with given anisotropy does
+exist. Anisotropic compact stellar type objects can be much more compact than
+the isotropic ones, and their radii may be close to their corresponding
+Schwarzschild radii. Upper bounds for the anisotropy parameter are also
+obtained from the analysis of the curvature invariants. General restrictions
+for the redshift and the total energy (including the gravitational
+contribution) for anisotropic stars are obtained in terms of the anisotropy
+parameter. Values of the surface redshift parameter greater than two could be
+the main observational signature for anisotropic stellar type objects.",0609061v1
+1998-08-25,Non-perturbative determination of anisotropy coefficients and pressure gap at the deconfining transition of QCD,"We propose a new non-perturbative method to compute derivatives of gauge
+coupling constants with respect to anisotropic lattice spacings (anisotropy
+coefficients). Our method is based on a precise measurement of the finite
+temperature deconfining transition curve in the lattice coupling parameter
+space extended to anisotropic lattices by applying the spectral density method.
+We determine the anisotropy coefficients for the cases of SU(2) and SU(3) gauge
+theories. A longstanding problem, when one uses the perturbative anisotropy
+coefficients, is a non-vanishing pressure gap at the deconfining transition
+point in the SU(3) gauge theory. Using our non-perturbative anisotropy
+coefficients, we find that this problem is completely resolved.",9808034v1
+1992-07-14,Contribution of Long Wavelength Gravitational Waves to the CMB Anisotropy,"We present an in depth discussion of the production of gravitational waves
+from an inflationary phase that could have occurred in the early universe,
+giving derivations for the resulting spectrum and energy density. We also
+consider the large-scale anisotropy in the cosmic microwave background
+radiation coming from these waves. Assuming that the observed quadrupole
+anisotropy comes mostly from gravitational waves (consistent with the
+predictions of a flat spectrum of scalar density perturbations and the measured
+dipole anisotropy) we describe in detail how to derive a value for the scale of
+inflation of $(1.5-5)\times 10^{16}$GeV, which is at a particularly interesting
+scale for particle physics. This upper limit corresponds to a 95\% confidence
+level upper limit on the scale of inflation assuming only that the quadrupole
+anisotropy from gravitational waves is not cancelled by another source. Direct
+detection of gravitational waves produced by inflation near this scale will
+have to wait for the next generation of detectors.",9207239v1
+2003-08-23,Braneworld cosmological models with anisotropy,"For a cosmological Randall-Sundrum braneworld with anisotropy, i.e., of
+Bianchi type, the modified Einstein equations on the brane include components
+of the five-dimensional Weyl tensor for which there are no evolution equations
+on the brane. If the bulk field equations are not solved, this Weyl term
+remains unknown, and many previous studies have simply prescribed it ad hoc. We
+construct a family of Bianchi braneworlds with anisotropy by solving the
+five-dimensional field equations in the bulk. We analyze the cosmological
+dynamics on the brane, including the Weyl term, and shed light on the relation
+between anisotropy on the brane and Weyl curvature in the bulk. In these
+models, it is not possible to achieve geometric anisotropy for a perfect fluid
+or scalar field -- the junction conditions require anisotropic stress on the
+brane. But the solutions can isotropize and approach a Friedmann brane in an
+anti-de Sitter bulk.",0308158v1
+2000-05-31,Anomalous scaling of a passive scalar in the presence of strong anisotropy,"Field theoretic renormalization group and the operator product expansion are
+applied to a model of a passive scalar field, advected by the Gaussian strongly
+anisotropic velocity field. Inertial-range anomalous scaling behavior is
+established, and explicit asymptotic expressions for the n-th order structure
+functions of scalar field are obtained; they are represented by superpositions
+of power laws with nonuniversal (dependent on the anisotropy parameters)
+anomalous exponents. In the limit of vanishing anisotropy, the exponents are
+associated with tensor composite operators built of the scalar gradients, and
+exhibit a kind of hierarchy related to the degree of anisotropy: the less is
+the rank, the less is the dimension and, consequently, the more important is
+the contribution to the inertial-range behavior. The leading terms of the even
+(odd) structure functions are given by the scalar (vector) operators. For the
+finite anisotropy, the exponents cannot be associated with individual operators
+(which are essentially ``mixed'' in renormalization), but the aforementioned
+hierarchy survives for all the cases studied. The second-order structure
+function is studied in more detail using the renormalization group and
+zero-mode techniques.",0005067v1
+2001-09-09,Light scattering by optically anisotropic scatterers II: T--matrix computations for radially and uniformly anisotropic droplets,"This is the second paper in a series on light scattering from optically
+anisotropic scatterers embedded in an isotropic medium. The apparently complex
+T-matrix theory involving mixing of angular momentum components turns out to be
+an efficient approach to calculating scattering in these systems. We present
+preliminary results of numerical calculations of the scattering by spherical
+droplets in some simple cases. The droplets contain optically anisotropic
+material with local radial or uniform anisotropy. We concentrate on cases in
+which the scattering is due only to the local optical anisotropy within the
+scatterer. For radial anisotropy we find non-monotonic dependence of the
+scattering cross-section on the degree of anisotropy can occur in a regime for
+which both the Rayleigh and semi-classical theories are inapplicable. For
+uniform anisotropy the cross-section is strongly dependent on the angle between
+the incident light and the optical axis, and for larger droplets this
+dependence is non-monotonic.",0109023v1
+2007-04-06,Model C critical dynamics of random anisotropy magnets,"We study the relaxational critical dynamics of the three-dimensional random
+anisotropy magnets with the non-conserved n-component order parameter coupled
+to a conserved scalar density. In the random anisotropy magnets the structural
+disorder is present in a form of local quenched anisotropy axes of random
+orientation. When the anisotropy axes are randomly distributed along the edges
+of the n-dimensional hypercube, asymptotical dynamical critical properties
+coincide with those of the random-site Ising model. However structural disorder
+gives rise to considerable effects for non-asymptotic critical dynamics. We
+investigate this phenomenon by a field-theoretical renormalization group
+analysis in the two-loop order. We study critical slowing down and obtain
+quantitative estimates for the effective and asymptotic critical exponents of
+the order parameter and scalar density. The results predict complex scenarios
+for the effective critical exponent approaching an asymptotic regime.",0704.0896v1
+2007-08-13,Angle dependent magnetoresistance measurements in Tl$_2$Ba$_2$CuO$_{6+δ}$ and the need for anisotropic scattering,"The angle-dependent interlayer magnetoresistance of overdoped
+Tl$_2$Ba$_2$CuO$_{6+\delta}$ has been measured in high magnetic fields up to 45
+Tesla. A conventional Boltzmann transport analysis with no basal-plane
+anisotropy in the cyclotron frequency $\omega_c$ or transport lifetime $\tau$
+is shown to be inadequate for explaining the data. We describe in detail how
+the analysis can be modified to incorporate in-plane anisotropy in these two
+key quantities and extract the degree of anisotropy for each by assuming a
+simple four-fold symmetry. While anisotropy in $\omega_c$ and other Fermi
+surface parameters may improve the fit, we demonstrate that the most important
+anisotropy is that in the transport lifetime, thus confirming its role in the
+physics of overdoped superconducting cuprates.",0708.1666v1
+2007-11-04,Secondary anisotropies of the CMB,"The Cosmic Microwave Background fluctuations provide a powerful probe of the
+dark ages of the universe through the imprint of the secondary anisotropies
+associated with the reionisation of the universe and the growth of structure.
+We review the relation between the secondary anisotropies and and the primary
+anisotropies that are directly generated by quantum fluctuations in the very
+early universe. The physics of secondary fluctuations is described, with
+emphasis on the ionisation history and the evolution of structure. We discuss
+the different signatures arising from the secondary effects in terms of their
+induced temperature fluctuations, polarisation and statistics. The secondary
+anisotropies are being actively pursued at present, and we review the future
+and current observational status.",0711.0518v1
+2007-12-08,Thermal and surface anisotropy effects on the magnetization reversal of a nanocluster,"The relaxation rate and temperature-dependent switching field curve of a
+spherical magnetic nanocluster are calculated by taking into account the effect
+of surface anisotropy via an effective anisotropy model. In particular, it is
+shown that surface anisotropy may change the thermally activated magnetization
+reversal by more than an order of magnitude, and that temperature-dependent
+switching field curves noticeably deviate from the Stoner-Wohlfarth astroid.
+With recent and future $\mu$-SQUID measurements in mind, we indicate how
+comparison of our results with experimental data on isolated clusters may allow
+one to obtain valuable information on surface anisotropy.",0712.1305v3
+2007-12-12,Analysis of anisotropy crossover due to oxygen in Pt/Co/MOx trilayer,"Extraordinary Hall effect and X-ray spectroscopy measurements have been
+performed on a series of Pt/Co/MOx trilayers (M=Al, Mg, Ta...) in order to
+investigate the role of oxidation in the onset of perpendicular magnetic
+anisotropy at the Co/MOx interface. It is observed that varying the oxidation
+time modifies the magnetic properties of the Co layer, inducing a magnetic
+anisotropy crossover from in-plane to out-of-plane. We focused on the influence
+of plasma oxidation on Pt/Co/AlOx perpendicular magnetic anisotropy. The
+interfacial electronic structure is analyzed via X-ray photoelectron
+spectroscopy measurements. It is shown that the maximum of out-of-plane
+magnetic anisotropy corresponds to the appearance of a significant density of
+Co-O bondings at the Co/AlOx interface.",0712.1905v1
+2008-01-22,The trispectrum of 21-cm background anisotropies as a probe of primordial non-Gaussianity,"The 21-cm anisotropies from the neutral hydrogen distribution prior to the
+era of reionization is a sensitive probe of primordial non-Gaussianity. Unlike
+the case with cosmic microwave background, 21-cm anisotropies provide
+multi-redshift information with frequency selection and is not damped at
+arcminute angular scales. We discuss the angular trispectrum of the 21-cm
+background anisotropies and discuss how the trispectrum signal generated by the
+primordial non-Gaussianity can be measured with the three-to-one correlator and
+the corresponding angular power spectrum. We also discuss the separation of
+primordial non-Gaussian information in the trispectrum with that generated by
+the subsequent non-linear gravitational evolution of the density field. While
+with the angular bispectrum of 21-cm anisotropies one can limit the second
+order corrections to the primordial fluctuations below f_NL< 1, using the
+trispectrum information we suggest that the third order coupling term, f_2 or
+g_NL, can be constrained to be arounde 10 with future 21-cm observations over
+the redshift interval of 50 to 100.",0801.3463v1
+2008-01-30,Particle-scale origins of shear strength in granular media,"The shear strength of cohesionless granular materials is generally attributed
+to the compactness or anisotropy of their microstructure. An open issue is how
+such compact or anisotropic microstructures, and thus the shear strength,
+depend on the particle properties. We first recall the role of fabric and force
+anisotropies with respect to the critical-state shear stress. Then, a model of
+accessible geometrical states in terms of particle connectivity and contact
+anisotropy is presented. This model incorporates in a simple way the fact that,
+due to steric exclusions, the highest levels of connectivity and anisotropy
+cannot be reached simultaneously, a property that affects seriously the shear
+strength. We also analyze the force anisotropy in the light of the specific
+role of weak forces in sustaining strong force chains and thus the main
+mechanism that underlies anisotropic force patterns. Finally, we briefly
+discuss the effect of interparticle friction, particle shape, size
+polydispersity and adhesion.",0801.4722v1
+2008-02-14,Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud,"Velocity anisotropy induced by MHD turbulence is investigated using
+computational simulations and molecular line observations of the Taurus
+molecular cloud. A new analysis method is presented to evaluate the degree and
+angle of velocity anisotropy using spectroscopic imaging data of interstellar
+clouds. The efficacy of this method is demonstrated on model observations
+derived from three dimensional velocity and density fields from the set of
+numerical MHD simulations that span a range of magnetic field strengths. The
+analysis is applied to 12CO J=1-0 imaging of a sub-field within the Taurus
+molecular cloud. Velocity anisotropy is identified that is aligned within 10
+degrees of the mean local magnetic field direction derived from optical
+polarization measurements. Estimated values of the field strength based on
+velocity anisotropy are consistent with results from other methods. When
+combined with new column density measurements for Taurus, our magnetic field
+strength estimate indicates that the envelope of the cloud is magnetically
+subcritical. These observations favor strong MHD turbulence within the low
+density, sub-critical, molecular gas substrate of the Taurus cloud.",0802.2084v1
+2008-07-08,Monte Carlo investigation of the magnetic anisotropy in Fe/Dy multilayers,"By Monte Carlo simulations in the canonical ensemble, we have studied the
+magnetic anisotropy in Fe/Dy amorphous multilayers. This work has been
+motivated by experimental results which show a clear correlation between the
+magnetic perpendicular anisotropy and the substrate temperature during
+elaboration of the samples. Our aim is to relate macroscopic magnetic
+properties of the multilayers to their structure, more precisely their
+concentration profile. Our model is based on concentration dependent exchange
+interactions and spin values, on random magnetic anisotropy and on the
+existence of locally ordered clusters that leads to a perpendicular
+magnetisation. Our results evidence that a compensation point occurs in the
+case of an abrupt concentration profile. Moreover, an increase of the
+noncollinearity of the atomic moments has been evidenced when the Dy anisotropy
+constant value grows. We have also shown the existence of inhomogeneous
+magnetisation profiles along the samples which are related to the concentration
+profiles.",0807.1262v1
+2008-08-28,Giant magnetic anisotropy of the bulk antiferromagnets IrMn and IrMn3,"Theoretical predictions of the magnetic anisotropy of antiferromagnetic
+materials are demanding due to a lack of experimental techniques which are
+capable of a direct measurement of this quantity. At the same time it is highly
+significant due to the use of antiferromagnetic components in magneto-resistive
+sensor devices where the stability of the antiferromagnet is of upmost
+relevance. We perform an ab-initio study of the ordered phases of IrMn and
+IrMn3, the most widely used industrial antiferromagnets. Calculating the form
+and the strength of the magnetic anisotropy allows the construction of an
+effective spin model, which is tested against experimental measurements
+regarding the magnetic ground state and the Neel temperature. Our most
+important result is the extremely strong second order anisotropy for IrMn3
+appearing in its frustrated triangular magnetic ground state, a surprising fact
+since the ordered L12 phase has a cubic symmetry. We explain this large
+anisotropy by the fact that cubic symmetry is locally broken for each of the
+three Mn sub-lattices.",0808.3900v1
+2008-09-04,Properties of anisotropic magnetic impurities on surfaces,"Using numerical renormalization group techniques, we study static and dynamic
+properties of a family of single-channel Kondo impurity models with axial
+magnetic anisotropy $DS_z^2$ terms; such models are appropriate to describe
+magnetic impurity atoms adsorbed on non-magnetic surfaces, which may exhibit
+surface Kondo effect. We show that for positive anisotropy $D$ and for any spin
+$S$, the systems behave at low temperatures as regular Fermi liquids with fully
+compensated impurity spin. The approach to the stable fixed point depends on
+the value of the spin $S$ and on the ratio $D/T_K^{(0)}$, where $T_K^{(0)}$ is
+the Kondo temperature in the absence of the anisotropy. For S=1, the screening
+occurs in two stages if $D<T_K^{(0)}$; the second Kondo temperature is
+exponentially reduced in this case. More generally, there is an effective
+spin-1/2 Kondo effect for any integer $S$ if $D<T_K^{(0)}$ and for any
+half-integer $S$ if $D>T_K^{(0)}$. For negative anisotropy $D$, the system is a
+non-Fermi liquid with residual anisotropic exchange interaction. However, the
+presence of transverse magnetic anisotropy $E(S_x^2-S_y^2)$ restores
+Fermi-liquid behavior in real systems.",0809.0759v1
+2008-10-28,Competition between Surface Energy and Elastic Anisotropies in the Growth of Coherent Solid State Dendrites,"A new phase field model of microstructural evolution is presented that
+includes the effects of elastic strain energy. The model's thin interface
+behavior is investigated by mapping it onto a recent model developed by
+Echebarria et al (Phys Rev E, 70:061604,2004). Exploiting this thin interface
+analysis the growth of solid state dendrites are simulated with diffuse
+interfaces and the phase field and mechanical equilibrium equations are solved
+in real space on an adaptive mesh. A morphological competition between surface
+energy anisotropy and elastic anisotropy is examined. Two dimensional
+simulations are reported that show that solid state dendritic structures
+undergo a transition from a surface dominated [10] growth direction to an
+elastically driven [11] growth direction by changes in the elastic anisotropy,
+the surface anisotropy and the supersaturation. Using the curvature and strain
+corrections to the equilibrium interfacial composition and linear stability
+theory for isotropic precipitates as calculated by Mullins and Sekerka, the
+dominant growth morphology is predicted.",0810.4978v1
+2008-11-03,Using CMBR analysis tools for flow anisotropies in relativistic heavy-ion collisions,"Recently we have shown that there are crucial similarities in the physics of
+cosmic microwave background radiation (CMBR) anisotropies and the flow
+anisotropies in relativistic heavy-ion collision experiments (RHICE). We also
+argued that, following CMBR anisotropy analysis, a plot of root-mean square
+values of the flow coefficients, calculated in a lab fixed frame for RHICE, can
+yield important information about the nature of initial state anisotropies and
+their evolution. Here we demonstrate the strength of this technique by showing
+that elliptic flow for non-central collisions can be directly determined from
+such a plot without any need for the determination of event-plane.",0811.0292v2
+2008-12-04,Might we eventually understand the origin of the dark matter velocity anisotropy?,"The density profile of simulated dark matter structures is fairly
+well-established, and several explanations for its characteristics have been
+put forward. In contrast, the radial variation of the velocity anisotropy has
+still not been explained. We suggest a very simple origin, based on the shapes
+of the velocity distributions functions, which are shown to differ between the
+radial and tangential directions. This allows us to derive a radial variation
+of the anisotropy profile which is in good agreement with both simulations and
+observations. One of the consequences of this suggestion is that the velocity
+anisotropy is entirely determined once the density profile is known. We
+demonstrate how this explains the origin of the \gamma-\beta relation, which is
+the connection between the slope of the density profile and the velocity
+anisotropy. These findings provide us with a powerful tool, which allows us to
+close the Jeans equations.",0812.1048v1
+2008-12-20,Magnetic anisotropy modulation of magnetite in Fe3O4/BaTiO3(100) epitaxial structures,"Temperature dependent magnetometry and transport measurements on epitaxial
+Fe3O4 films grown on BaTiO3(100) single crystals by molecular beam epitaxy show
+a series of discontinuities, that are due to changes in the magnetic anisotropy
+induced by strain in the different crystal phases of BaTiO3. The magnetite film
+is under tensile strain at room temperature, which is ascribed to the lattice
+expansion of BaTiO3 at the cubic to tetragonal transition, indicating that the
+magnetite film is relaxed at the growth temperature. From the magnetization
+versus temperature curves, the variation in the magnetic anisotropy is
+determined and compared with the magnetoelastic anisotropies. These results
+demonstrate the possibility of using the piezoelectric response of BaTiO3 to
+modulate the magnetic anisotropy of magnetite films.",0812.3930v1
+2009-02-02,Critical Anisotropies of a Geometrically-Frustrated Triangular-Lattice Antiferromagnet,"This work examines the critical anisotropy required for the local stability
+of the collinear ground states of a geometrically-frustrated triangular-lattice
+antiferromagnet (TLA). Using a Holstein-Primakoff expansion, we calculate the
+spin-wave frequencies for the 1, 2, 3, 4, and 8-sublattice (SL) ground states
+of a TLA with up to third neighbor interactions. Local stability requires that
+all spin-wave frequencies are real and positive. The 2, 4, and 8-SL phases
+break up into several regions where the critical anisotropy is a different
+function of the exchange parameters. We find that the critical anisotropy is a
+continuous function everywhere except across the 2-SL/3-SL and 3-SL/4-SL phase
+boundaries, where the 3-SL phase has the higher critical anisotropy.",0902.0359v1
+2009-03-04,"Resistivity Anisotropy of $AE$Fe$_2$As$_2$ ($AE$ =Ca, Sr, Ba): direct versus Montgomery technique measurements","The anisotropy of electrical resistivity was measured in parent compounds of
+the iron-arsenic high temperature superconductors, AEFe2As2 with Alkali Earth
+elements AE=Ca,Sr, Ba. Measurements were performed using both the Montgomery
+technique and direct resistivity measurements on samples cut along principal
+crystallographic directions. The anisotropy ratio \gamma_\rho=\rho_c/\rho_a is
+well below 10 for all compounds in the whole temperature range studied (4 to
+300 K), in notable contrast to previous reports. The anisotropy at room
+temperature increases from about 2 in Ca, to about 4 in Sr and Ba. In all
+compounds the resistivity ratio decreases on cooling through the
+structural/antiferromagnetic transition temperature T_{SM}, with the change
+mainly coming from stronger variation in \rho_a as compared with \rho_c. This
+suggests that the transitions stronger affect the two-dimensional parts of the
+Fermi surface. We compare our experimental observations with band structure
+calculations, and find similar trend in the evolution of anisotropy with the
+size of AE ion. Our results show that the electronic structure of the iron
+pnictides has large contribution from three-dimensional areas of the Fermi
+surface.",0903.0820v1
+2009-03-19,Magnetic Anisotropy and Magnetization Dynamics of Individual Atoms and Clusters of Fe and Co on Pt(111),"The recently discovered giant magnetic anisotropy of single magnetic Co atoms
+raises the hope of magnetic storage in small clusters. We present a joint
+experimental and theoretical study of the magnetic anisotropy and the spin
+dynamics of Fe and Co atoms, dimers, and trimers on Pt(111). Giant anisotropies
+of individual atoms and clusters as well as lifetimes of the excited states
+were determined with inelastic scanning tunneling spectroscopy. The short
+lifetimes due to hybridization-induced electron-electron scattering oppose the
+magnetic stability provided by the magnetic anisotropies.",0903.3337v1
+2009-06-08,Tunable magnetic properties of arrays of Fe(110) nanowires grown on kinetically-grooved W(110) self-organized templates,"We report a detailed magnetic study of a new type of self-organized nanowires
+disclosed briefly previously [B. Borca et al., Appl. Phys. Lett. 90, 142507
+(2007)]. The templates, prepared on sapphire wafers in a kinetically-limited
+regime, consist of uniaxially-grooved W(110) surfaces, with a lateral period
+here tuned to 15nm. Fe deposition leads to the formation of (110) 7 nm-wide
+wires located at the bottom of the grooves. The effect of capping layers (Mo,
+Pd, Au, Al) and underlayers (Mo, W) on the magnetic anisotropy of the wires was
+studied. Significant discrepancies with figures known for thin flat films are
+evidenced and discussed in terms of step anisotropy and strain-dependent
+surface anisotropy. Demagnetizing coeffcients of cylinders with a triangular
+isosceles cross-section have also been calculated, to estimate the contribution
+of dipolar anisotropy. Finally, the dependence of magnetic anisotropy with the
+interface element was used to tune the blocking temperature of the wires, here
+from 50K to 200 K.",0906.1510v1
+2009-07-02,Large Scale Cosmic Ray Anisotropy With IceCube,"We report on a study of the anisotropy in the arrival direction of cosmic
+rays with a median energy per Cosmic Ray (CR) particle of ~ 14 TeV using data
+from the IceCube detector. IceCube is a neutrino observatory at the
+geographical South Pole, when completed it will comprise 80 strings plus 6
+additional strings for the low energy array Deep Core. The strings are deployed
+in the deep ice between 1,450 and 2,450 meters depth, each string containing 60
+optical sensors. The data used in this analysis were collected from April 2007
+to March 2008 with 22 deployed strings. The data contain ~ 4.3 billion downward
+going muon events. A two-dimensional skymap is presented with an evidence of
+0.06% large scale anisotropy. The energy dependence of this anisotropy at
+median energies per CR particle of 12 TeV and 126 TeV is also presented in this
+work. This anisotropy could arise from a number of possible effects; it could
+further enhance the understanding of the structure of the galactic magnetic
+field and possible cosmic ray sources.",0907.0498v2
+2009-08-07,Estimators for CMB Statistical Anisotropy,"We use quadratic maximum-likelihood (QML) estimators to constrain models with
+Gaussian but statistically anisotropic Cosmic Microwave Background (CMB)
+fluctuations, using CMB maps with realistic sky-coverage and instrumental
+noise. This approach is optimal when the anisotropy is small, or when checking
+for consistency with isotropy. We demonstrate the power of the QML approach by
+applying it to the WMAP data to constrain several models which modulate the
+observed CMB fluctuations to produce a statistically anisotropic sky. We first
+constrain an empirically motivated spatial modulation of the observed CMB
+fluctuations, reproducing marginal evidence for a dipolar modulation pattern
+with amplitude 7% at L < 60, but demonstrate that the effect decreases at
+higher multipoles and is 1% at L~500. We also look for evidence of a
+direction-dependent primordial power spectrum, finding a very statistically
+significant quadrupole signal nearly aligned with the ecliptic plane; however
+we argue this anisotropy is largely contaminated by observational systematics.
+Finally, we constrain the anisotropy due to a spatial modulation of adiabatic
+and isocurvature primordial perturbations, and discuss the close relationship
+between anisotropy and non-Gaussianity estimators.",0908.0963v4
+2009-08-10,Magnetic fluctuation power near proton temperature anisotropy instability thresholds in the solar wind,"The proton temperature anisotropy in the solar wind is known to be
+constrained by the theoretical thresholds for pressure anisotropy-driven
+instabilities. Here we use approximately 1 million independent measurements of
+gyroscale magnetic fluctuations in the solar wind to show for the first time
+that these fluctuations are enhanced along the temperature anisotropy
+thresholds of the mirror, proton oblique firehose, and ion cyclotron
+instabilities. In addition, the measured magnetic compressibility is enhanced
+at high plasma beta ($\beta_\parallel \gtrsim 1$) along the mirror instability
+threshold but small elsewhere, consistent with expectations of the mirror mode.
+The power in this frequency (the 'dissipation') range is often considered to be
+driven by the solar wind turbulent cascade, an interpretation which should be
+qualified in light of the present results. In particular, we show that the
+short wavelength magnetic fluctuation power is a strong function of
+collisionality, which relaxes the temperature anisotropy away from the
+instability conditions and reduces correspondingly the fluctuation power.",0908.1274v1
+2009-09-07,Bianchi type III models with anisotropic dark energy,"The general form of the anisotropy parameter of the expansion for Bianchi
+type-III metric is obtained in the presence of a single diagonal imperfect
+fluid with a dynamically anisotropic equation of state parameter and a
+dynamical energy density in general relativity. A special law is assumed for
+the anisotropy of the fluid which reduces the anisotropy parameter of the
+expansion to a simple form. The exact solutions of the Einstein field
+equations, under the assumption on the anisotropy of the fluid, are obtained
+for exponential and power-law volumetric expansions. The isotropy of the fluid,
+space and expansion are examined. It is observed that the universe can approach
+to isotropy monotonically even in the presence of an anisotropic fluid. The
+anisotropy of the fluid also isotropizes at later times for accelerating models
+and evolves into the well-known cosmological constant in the model for
+exponential volumetric expansion.",0909.1025v1
+2010-01-07,Jet-photons from an anisotropic {\em Quark-Gluon-Plasma},"We calculate the $p_T$ distributions of jet conversion photons from {\em
+Quark Gluon Plasma} with pre-equilibrium momentum-space anisotropy. A
+phenomenological model has been used for the time evolution of hard momentum
+scale $p_{\rm hard}(\tau)$ and anisotropy parameter $\xi(\tau)$. As a result of
+pre-equilibrium momentum-space anisotropy, we find significant modification of
+the jet conversion photon $p_T$ distribution. For example, with {\em fixed
+initial condition} (FIC) pre-equilibrium anisotropy, we predict significant
+enhancement of the jet-photon $p_T$ distribution in the entire region, whereas
+for pre-equilibrium anisotropy with {\em fixed final multiplicity} (FFM),
+suppression of the jet conversion photons $p_T$ distribution is observed. The
+results with FFM (as it is the most realistic situation) have been compared
+with high $p_T$ PHENIX photon data. It is found that the data is reproduced
+well if the isotropization time lies within $1.5$ fm/c.",1001.1054v2
+2010-01-20,On the global density slope-anisotropy inequality,"Starting from the central density slope-anisotropy theorem of An and Evans
+(2006), recent investigations have shown that the involved density
+slope-anisotropy inequality holds not only at the center, but at all radii
+(i.e. globally) in a very large class of spherical systems with positive
+phase-space distribution function. Here we present some additional analytical
+cases that further extend the validity of the global density slope-anisotropy
+inequality. These new results, several numerical evidences, and the absence of
+known counter-examples, lead us to conjecture that the global density
+slope-anisotropy inequality could actually be a universal property of spherical
+systems with positive distribution function.",1001.3632v1
+2010-02-11,Electron temperature anisotropy in an expanding plasma: Particle-in-Cell simulations,"We perform fully-kinetic particle-in-cell simulations of an hot plasma that
+expands radially in a cylindrical geometry. The aim of the paper is to study
+the consequent development of the electron temperature anisotropy in an
+expanding plasma flow as found in a collisionless stellar wind. Kinetic plasma
+theory and simulations have shown that the electron temperature anisotropy is
+controlled by fluctuations driven by electromagnetic kinetic instabilities. In
+this study the temperature anisotropy is driven self-consistently by the
+expansion. While the expansion favors an increase of parallel anisotropy
+($T_\parallel>T_\perp$), the onset of the firehose instability will tend to
+decrease it. We show the results for a supersonic, subsonic, and static
+expansion flows, and suggest possible applications of the results for the solar
+wind and other stellar winds.",1002.2349v1
+2010-03-02,Non-detection of a statistically anisotropic power spectrum in large-scale structure,"We search a sample of photometric luminous red galaxies (LRGs) measured by
+the Sloan Digital Sky Survey (SDSS) for a quadrupolar anisotropy in the
+primordial power spectrum, in which P(\vec{k}) is an isotropic power spectrum
+P(k) multiplied by a quadrupolar modulation pattern. We first place limits on
+the 5 coefficients of a general quadrupole anisotropy. We also consider
+axisymmetric quadrupoles of the form P(\vec{k}) = P(k){1 +
+g_*[(\hat{k}\cdot\hat{n})^2-1/3]} where \hat{n} is the axis of the anisotropy.
+When we force the symmetry axis \hat{n} to be in the direction (l,b)=(94
+degrees,26 degrees) identified in the recent Groeneboom et al. analysis of the
+cosmic microwave background, we find g_*=0.006+/-0.036 (1 sigma). With uniform
+priors on \hat{n} and g_* we find that -0.41<g_*<+0.38 with 95% probability,
+with the wide range due mainly to the large uncertainty of asymmetries aligned
+with the Galactic Plane. In none of these three analyses do we detect evidence
+for quadrupolar power anisotropy in large scale structure.",1003.0673v2
+2010-04-19,Analytic formulae for the off-center CMB anisotropy in a general spherically symmetric universe,"The local void model has recently attracted considerable attention because it
+can explain the apparent accelerated expansion of the present universe without
+introducing dark energy. However, in order to justify this model as an
+alternative to the standard $\Lambda$CDM cosmology, the model should be tested
+by various observations, such as the CMB temperature anisotropy, besides the
+distance-redshift relation of SNIa. For this purpose, we derive analytic
+formulae for the dipole and quadrupole moments of the CMB temperature
+anisotropy that hold for any spherically symmetric universe model and can be
+used to compare consequences of such a model with observations of the CMB
+temperature anisotropy rigorously. We check that our formulae are consistent
+with the numerical studies previously made for the CMB temperature anisotropy
+in the void model. We also update the constraints concerning the location of
+the observers in the void model by applying our analytic dipole formula with
+the latest WMAP data.",1004.3089v2
+2010-05-10,Anisotropy of Magnetic Interactions in the Spin-Ladder Compound (C$_5$H$_{12}$N)$_2$CuBr$_4$,"Magnetic excitations in the spin-ladder material (C$_5$H$_{12}$N)$_2$CuBr$_4$
+[BPCB] are probed by high-resolution multi-frequency electron spin resonance
+(ESR) spectroscopy. Our experiments provide a direct evidence for a biaxial
+anisotropy ($\sim 5\%$ of the dominant exchange interaction), that is in
+contrast to a fully isotropic spin-ladder model employed for this system
+previously. It is argued that this anisotropy in BPCB is caused by spin-orbit
+coupling, which appears to be important for describing magnetic properties of
+this compound. The zero-field zone-center gap in the excitation spectrum of
+BPCB, $\Delta_0/k_{B}=16.5$ K, is detected directly. Furthermore, an ESR
+signature of the inter-ladder exchange interactions is obtained. The detailed
+characterization of the anisotropy in BPCB completes the determination of the
+full spin hamiltonian of this exceptional spin-ladder material and shows ways
+to study anisotropy effects in spin ladders.",1005.1474v1
+2010-06-11,How general is the global density slope-anisotropy inequality?,"Following the seminal result of An & Evans, known as the central density
+slope-anisotropy theorem, successive investigations unexpectedly revealed that
+the density slope-anisotropy inequality holds not only at the center, but at
+all radii in a very large class of spherical systems whenever the phase-space
+distribution function is positive. In this paper we derive a criterion that
+holds for all spherical systems in which the augmented density is a separable
+function of radius and potential: this new finding allows to unify all the
+previous results in a very elegant way, and opens the way for more general
+investigations. As a first application, we prove that the global density
+slope-anisotropy inequality is also satisfied by all the explored additional
+families of multi-component stellar systems. The present results, and the
+absence of known counter-examples, lead us to conjecture that the global
+density slope-anisotropy inequality could actually be a universal property of
+spherical systems with positive distribution function.",1006.2344v1
+2010-06-18,Azimuthal anisotropy of neutral pion production in Au+Au collisions at sqrt(s_NN) = 200 GeV: Path-length dependence of jet quenching and the role of initial geometry,"We have measured the azimuthal anisotropy of pi0's for 1 < pT < 18 GeV/c for
+Au+Au collisions at sqrt s_NN = 200 GeV. The observed anisotropy shows a
+gradual decrease in 3 < pT < 7 - 10 GeV/c, but remains positive beyond 10
+GeV/c. The magnitude of this anisotropy is under-predicted, up to at least 10
+GeV/c, by current perturbative QCD (pQCD) energy-loss model calculations. An
+estimate of the increase in anisotropy expected from initial-geometry
+modification due to gluon saturation effects and initial-geometry fluctuations
+is insufficient to account for this discrepancy. Calculations which implement a
+path length dependence steeper than what is implied by current pQCD energy-loss
+models, show reasonable agreement with the data.",1006.3740v1
+2010-07-20,Conductivity anisotropy in the antiferromagnetic state of iron pnictides,"Recent experiments on iron pnictides have uncovered a large in-plane
+resistivity anisotropy with a surprising result: the system conducts better in
+the antiferromagnetic x direction than in the ferromagnetic y direction. We
+address this problem by calculating the ratio of the Drude weight along the x
+and y directions, Dx/Dy, for the mean-field Q=(\pi,0) magnetic phase diagram of
+a five-band model for the undoped pnictides. We find that Dx/Dy ranges between
+0.3 < D_x/D_y < 1.4 for different interaction parameters. Large values of
+orbital ordering favor an anisotropy opposite to the one found experimentally.
+On the other hand D_x/D_y is strongly dependent on the topology and morfology
+of the reconstructed Fermi surface. Our results points against orbital ordering
+as the origin of the observed conductivity anisotropy, which may be ascribed to
+the anisotropy of the Fermi velocity.",1007.3483v2
+2010-09-09,A Theoretical Diagnosis on Light Speed Anisotropy from GRAAL Experiment,"The light speed anisotropy, i.e., the variation of the light speed with
+respect to the direction in an ""absolute"" reference frame, is a profound issue
+in physics. The one-way experiment, performed at the GRAAL facility of the
+European Synchrotron Radiation Facility (ESRF) in Grenoble, reported results on
+the light speed anisotropy by Compton scattering of laser photons on
+high-energy electrons. So far, most articles concerned with the GRAAL data have
+established only the upper bounds on the anisotropy parameters based on
+available theories. We use a new theory of the Lorentz invariance violation to
+analyse the available GRAAL data and obtain the stringent upper limit of the
+order $2.4\times10^{-14}$ on the Lorentz violation parameters. In the meantime,
+we also can reproduce the allowed light speed anisotropy appearing in the
+azimuthal distribution of the GRAAL experimental data, and find that the
+best-fit parameters are compatible with the competitive upper bounds.",1009.1675v2
+2010-09-09,Translation of collision geometry fluctuations into momentum anisotropies in relativistic heavy-ion collisions,"We develop a systematic framework for the study of the initial collision
+geometry fluctuations in relativistic heavy-ion collisions and investigate how
+they evolve through different stages of the fireball history and translate into
+final particle momentum anisotropies. We find in our event-by-event analysis
+that only the few lowest momentum anisotropy parameters survive after the
+hydrodynamical evolution of the system. The geometry of the produced medium is
+found to be affected by the pre-equilibrium evolution of the medium and the
+thermal smearing of the discretized event-by-event initial conditions, both of
+which tend to smear out the spatial anisotropies. We find such effects to be
+more prominent for higher moments than for lower moments. The correlations
+between odd and even spatial anisotropy parameters during the pre-equilibrium
+expansion are quantitatively studied and found to be small. Our study provides
+a theoretical foundation for the understanding of initial state fluctuations
+and the collective expansion dynamics in relativistic heavy-ion collisions.",1009.1847v2
+2010-09-29,Effects of the galactic magnetic field upon large scale anisotropies of extragalactic Cosmic Rays,"The large scale pattern in the arrival directions of extragalactic cosmic
+rays that reach the Earth is different from that of the flux arriving to the
+halo of the Galaxy as a result of the propagation through the galactic magnetic
+field. Two different effects are relevant in this process: deflections of
+trajectories and (de)acceleration by the electric field component due to the
+galactic rotation. The deflection of the cosmic ray trajectories makes the flux
+intensity arriving to the halo from some direction to appear reaching the Earth
+from another direction. This applies to any intrinsic anisotropy in the
+extragalactic distribution or, even in the absence of intrinsic anisotropies,
+to the dipolar Compton-Getting anisotropy induced when the observer is moving
+with respect to the cosmic rays rest frame. For an observer moving with the
+solar system, cosmic rays traveling through far away regions of the Galaxy also
+experience an electric force coming from the relative motion (due to the
+rotation of the Galaxy) of the local system in which the field can be
+considered as being purely magnetic. This produces small changes in the
+particles momentum that can originate large scale anisotropies even for an
+isotropic extragalactic flux.",1009.5891v1
+2010-10-20,On the universality of the global slope -- anisotropy inequality,"Recently, some intriguing results have lead to speculations whether the
+central density slope -- velocity dispersion anisotropy inequality (An & Evans)
+actually holds at all radii for spherical dynamical systems. We extend these
+studies by providing a complete analysis of the global slope -- anisotropy
+inequality for all spherical systems in which the augmented density is a
+separable function of radius and potential. We prove that these systems indeed
+satisfy the global inequality if their central anisotropy is $\beta_0\leq 1/2$.
+Furthermore, we present several systems with $\beta_0 > 1/2$ for which the
+inequality does not hold, thus demonstrating that the global density slope --
+anisotropy inequality is not a universal property. This analysis is a
+significant step towards an understanding of the relation for general spherical
+systems.",1010.4301v1
+2010-11-06,Effect of anisotropy on the field induced quantum critical properties of the three dimensional s=1/2 Heisenberg model,"The field induced quantum critical properties of the three dimensional
+spin-1/2 anisotropic antiferromagnetic Heisenberg model has been studied. We
+have investigated the quantum phase transition between the spiral order and
+field induced ferromagnetic order by means of Bose-Einstein condensation of
+magnons in terms of a bosonic representation. The effect of in-plane anisotropy
+on the critical properties has been studied via the bosonic model by Green's
+function approach. We have found an analytic expression for the gap exponent in
+addition to numerical results for the critical magnetic field in terms of
+anisotropy parameter. The in-plane anisotropy breaks the U(1) symmetry
+explicitly which changes the universal behavior by a drastic change on the gap
+exponent. Moreover, the critical magnetic field depends strongly on the
+in-plane anisotropies. The divergence of the transverse structure factor at the
+antiferromagnetic wave vector confirms the onset of the magnetic order which
+scales with the negative value of gap exponent as the magnetic field approaches
+the critical one. The transverse staggered magnetization as an order parameter
+vanishes with exponent $\beta=0.5$ when the magnetic field reaches its critical
+value in low field region.",1011.1574v1
+2010-11-24,Anisotropies in the gamma-ray sky from millisecond pulsars,"Pulsars emerge in the Fermi era as a sizable population of gamma-ray sources.
+Millisecond pulsars (MSPs) constitute an older subpopulation whose sky
+distribution extends to high Galactic latitudes, and it has been suggested that
+unresolved members of this class may contribute a significant fraction of the
+measured large-scale isotropic gamma-ray background (IGRB). We investigate the
+possible energy-dependent contribution of unresolved MSPs to the anisotropy of
+the Fermi-measured IGRB. For observationally-motivated MSP population models,
+we show that the preliminary Fermi anisotropy measurement places an interesting
+constraint on the abundance of MSPs in the Galaxy and the typical MSP flux,
+about an order of magnitude stronger than constraints on this population
+derived from the intensity of the IGRB alone. We also examine the possibility
+of a MSP component in the IGRB mimicking a dark matter signal in
+anisotropy-based searches, and conclude that the energy dependence of an
+anisotropy signature would distinguish MSPs from all but very light dark matter
+candidates.",1011.5501v2
+2010-12-06,Ab-initio description of the magnetic shape anisotropy due to the Breit interaction,"A quantum-mechanical description of the magnetic shape anisotropy, that is
+usually ascribed to the classical magnetic dipole-dipole interaction, has been
+developed. This is achieved by including the Breit-interaction, that can be
+seen as an electronic current-current interaction in addition to the
+conventional Coulomb interaction, within fully relativistic band structure
+calculations. The major sources of the magnetic anisotropy, spin-orbit coupling
+and the Breit-interaction, are treated coherently this way. This seems to be
+especially important for layered systems for which often both sources
+contribute with opposite sign to the magnetic anisotropy energy. Applications
+to layered transition metal systems are presented to demonstrate the
+implications of this new approach in treating the magnetic shape anisotropy.",1012.1115v1
+2011-03-15,Amplitudes of thermal and kinetic Sunyaev-Zel'dovich signals from small-scale CMB anisotropies,"While the arcminute-scale Cosmic Microwave Background (CMB) anisotropies are
+due to secondary effects, point sources dominate the total anisotropy power
+spectrum. At high frequencies the point sources are primarily in the form of
+dusty, star-forming galaxies. Both Herschel and Planck have recently measured
+the anisotropy power spectrum of cosmic infrared background (CIB) generated by
+dusty, star-forming galaxies from degree to sub-arcminute angular scales,
+including the non-linear clustering of these galaxies at multipoles of 3000 to
+6000 relevant to CMB secondary anisotropy studies. We scale the CIB angular
+power spectra to CMB frequencies and interpret the combined WMAP-7 year and
+arcminute-scale Atacama Cosmology Telescope (ACT) and South Pole Telescope
+(SPT) CMB power spectra measurements to constrain the Sunyaev-Zel'dovich (SZ)
+effects. Allowing the CIB clustering amplitude to vary, we constrain the
+amplitudes of thermal and kinetic SZ power spectra at 150 GHz.",1103.3051v2
+2011-03-31,Constraints on velocity anisotropy of spherical systems with separable augmented densities,"If the augmented density of a spherical anisotropic system is assumed to be
+multiplicatively separable to functions of the potential and the radius, the
+radial function, which can be completely specified by the behavior of the
+anisotropy parameter alone, also fixes the anisotropic ratios of every
+higher-order velocity moment. It is inferred from this that the non-negativity
+of the distribution function necessarily limits the allowed behaviors of the
+radial function. This restriction is translated into the constraints on the
+behavior of the anisotropy parameter. We find that not all radial variations of
+the anisotropy parameter satisfy these constraints and thus that there exist
+anisotropy profiles that cannot be consistent with any separable augmented
+density.",1104.0014v2
+2011-04-11,Asymmetric magnetization splitting in diamond domain structure: Dependence on exchange interaction and anisotropy,"The distributions of magnetization orientation for both Landau and diamond
+domain structures in nano-rectangles have been investigated by micromagnetic
+simulation with various exchange coefficient and anisotropy constant. Both
+symmetric and asymmetric magnetization splitting are found in diamond domain
+structure, as well as only symmetric magnetization splitting in Landau
+structure. In the Landau structure, the splitting angle increases with the
+exchange coefficient but decreases slightly with the anisotropy constant,
+suggesting that the exchange interaction mainly contributes to the
+magnetization splitting in Landau structure. However in the diamond structure,
+the splitting angle increases with the anisotropy constant but derceases with
+the exchange coefficient, indicating that the magnetization splitting in
+diamond structure is resulted from magnetic anisotropy.",1104.1819v1
+2011-05-23,Orbitally and Magnetically Induced Anisotropy in Iron-based Superconductors,"Recent experimental developments in the iron pnictides have unambiguously
+demonstrated the existence of in-plane electronic anisotropy in the absence of
+the long-range magnetic order. Such anisotropy can arise from orbital ordering,
+which is described by an energy splitting between the two otherwise degenerate
+$d_{xz}$ and $d_{yz}$ orbitals. By including this phenomenological orbital
+order into a five-orbital Hubbard model, we obtain the mean-field solutions
+where the magnetic order is determined self-consistently. Despite sensitivity
+of the resulting states to the input parameters, we find that a weak orbital
+order that places the $d_{yz}$ orbital slightly higher in energy than the
+$d_{xz}$ orbital, combined with intermediate on-site interactions, produces
+band dispersions that are compatible with the photoemission results. In this
+regime, the stripe antiferromagnetic order is further stabilized and the
+resistivity displays the observed anisotropy. We also calculate the optical
+conductivity and show that it agrees with the temperature evolution of the
+anisotropy seen experimentally.",1105.4630v3
+2011-07-14,Microstructure and magnetic anisotropy of electrospun Cu$_{1-x}$Zn$_x$Fe$_2$O$_4$ nanofibers: A local probe study,"Understanding the phenomena at the nanometer scale is of fundamental
+importance for future improvements of desired properties of nanomaterials. We
+report a detailed investigation of the microstructure and the resulting
+magnetic anisotropy by magnetic, transmission electron microscope (TEM) and
+M\""ossbauer measurements of the electrospun Cu$_{1-x}$Zn$_x$Fe$_2$O$_4$
+nanofibers. Our results show that the electrospun Cu$_{1-x}$Zn$_x$Fe$_2$O$_4$
+nanofibers exhibit nearly isotropic magnetic anisotropy. TEM measurements
+indicate that the nanofibers are composed of loosely connected and randomly
+aligned nanograins. As revealed by the Henkel plot, these nanofibers and the
+nanograins within the nanofibers are dipolar coupled, which reduces the
+effective shape anisotropy leading to a nearly random configuration of the
+magnetic moments inside the nanofibers, hence, the observed nearly isotropic
+magnetic anisotropy can be easily understood.",1107.2820v2
+2011-08-19,Magnetic and structural anisotropies of Co2FeAl Heusler alloy epitaxial thin films,"This paper shows the correlation between chemical order, lattice strains and
+magnetic properties of Heusler Co2FeAl films epitaxially grown on MgO(001). A
+detailed magnetic characterization has been performed using vector field
+magnetometery combined with numerical Stoner-Wohlfarth analysis. We demonstrate
+the presence of three types of in-plane anisotropies: one biaxial, as expected
+for the cubic symmetry, and other two uniaxial ones. The three anisotropies
+show different behavior with the annealing temperature. The biaxial anisotropy
+shows a monotonous increase. The uniaxial anisotropy, parallel with the hard
+biaxial axes, related to the chemical homogeneity, decreases, while the other,
+supposed to have magnetostatic origin, remains constant.",1108.4043v2
+2011-10-12,Origin of perpendicular anisotropy in thin Co/Pt bilayers grown on alumina,"We investigate in this paper the origin of perpendicular anisotropy in Co
+(1.6 nm)/Pt (3.0 nm) bilayers grown on alumina and annealed up to
+650$^{\circ}$C. Above 350$^{\circ}$C, all layers exhibit perpendicular
+anisotropy. Then coercive fields increase linearly with annealing temperature
+following two different rates: 0.05 T/100$^{\circ}$C below 550$^{\circ}$C and
+0.8 T/100$^{\circ}$C above. By making careful structural characterizations
+using x-ray diffraction and transmission electron microscopy, we demonstrate
+the presence of short range correlation of L1$_{1}$ type below 550$^{\circ}$C
+whereas above 550$^{\circ}$C, L1$_{0}$ chemical ordering is observed. We
+conclude that perpendicular anisotropy observed in Co/Pt bilayers grown on
+alumina and annealed may not only be due to interface anisotropy as usually
+invoked but also to CoPt alloying and chemical ordering that take place during
+post-growth annealing.",1110.2628v1
+2011-11-08,Issues on Generating Primordial Anisotropies at the End of Inflation,"We revisit the idea of generating primordial anisotropies at the end of
+inflation in models of inflation with gauge fields. To be specific we consider
+the charged hybrid inflation model where the waterfall field is charged under a
+U(1) gauge field so the surface of end of inflation is controlled both by
+inflaton and the gauge fields. Using delta N formalism properly we find that
+the anisotropies generated at the end of inflation from the gauge field
+fluctuations are exponentially suppressed on cosmological scales. This is
+because the gauge field evolves exponentially during inflation while in order
+to generate appreciable anisotropies at the end of inflation the spectator
+gauge field has to be frozen and scale invariant. We argue that this is a
+generic feature, that is, one can not generate observable anisotropies at the
+end of inflation within an FRW background.",1111.1919v3
+2011-10-26,Testing for Anisotropy of Space via an Extension of Special Relativity,"In special relativity, testing for spatial anisotropy usually means testing
+for anisotropic propagation of light. This paper explores a different
+possibility, in which light is still assumed to propagate isotropically in all
+frames with an invariant speed, yet other physical effects exhibit a direction
+dependence. If spatial isotropy is not assumed in the derivation of the
+coordinates transformations, the resulting equations differ from the Lorentz
+relations by an additional factor $(\dfrac{c - v}{c + v})^{\kappa}$, where
+$\kappa$ is the anisotropy exponent, which depends on the direction chosen as
+the x-axis. Time dilation and length contractions become direction dependent.
+The anisotropy exponent is frame-independent, so no preferred isotropic frame
+exists if $\kappa$ is non-vanishing. The Doppler shift can be used to measure
+this exponent and determine experimentally the degree of anisotropy our
+universe actually possesses.",1111.4423v1
+2012-01-20,The Relation between Ion Temperature Anisotropy and Formation of Slow Shocks in Collisionless Magnetic Reconnection,"We perform a two-dimensional simulation by using an electromagnetic hybrid
+code to study the formation of slow-mode shocks in collisionless magnetic
+reconnection in low beta plasmas, and we focus on the relation between the
+formation of slow shocks and the ion temperature anisotropy enhanced at the
+shock downstream region. It is known that as magnetic reconnection develops,
+the parallel temperature along the magnetic field becomes large in association
+with the anisotropic PSBL (plasma sheet boundary layer) ion beams, and this
+temperature anisotropy has a tendency to suppress the formation of slow shocks.
+Based on our simulation result, we found that the slow shock formation is
+suppressed due to the large temperature anisotropy near the X-type region, but
+the ion temperature anisotropy relaxes with increasing the distance from the
+magnetic neutral point. As a result, two pairs of current structures, which are
+the strong evidence of dissipation of magnetic field in slow shocks, are formed
+at the distance x > 115 ion inertial lengths from the neutral point.",1201.4213v1
+2012-03-12,A Search for Small-Scale Anisotropy of PeV Cosmic Rays,"Recent results of Milagro, Tibet, ARGO-YBJ and IceCube experiments on the
+small-scale anisotropy of Galactic cosmic rays (CRs) with energies from units
+up to a few hundred TeV arise a question on a possible nature of the observed
+phenomenon, as well as on the anisotropy of CRs at higher energies. An analysis
+of a small-scale anisotropy of CRs with energies at around PeV registered with
+the EAS MSU array presented in the article, reveals a number of regions with an
+excessive flux. A typical size of the regions varies from 3 up to 12 degrees.
+We study correlation of these regions with positions of potential astrophysical
+sources of CRs and discuss a possible origin of the observed anisotropy.",1203.2472v1
+2012-04-03,Tuning entanglement and ergodicity in two-dimensional spin systems using impurities and anisotropy,"We consider the entanglement in a two dimensional XY model in an external
+magnetic field h. The model consists of a set of 7 localized spin-1/2 particles
+in a two dimensional triangular lattice coupled through nearest neighbor
+exchange interaction J. We examine the effect of single and double impurities
+in the system as well as the degree of anisotropy on the nearest neighbor
+entanglement and ergodicity of the system. We have found that the entanglement
+of the system at the different degrees of anisotropy mimics that of the one
+dimensional spin systems at the extremely small and large values of the
+parameter h/J. The entanglement of the Ising and partially anisotropic system
+show phase transition in the vicinity of h/J = 2 while the entanglement of the
+isotropic system suddenly vanishes there. Also we investigate the dynamic
+response of the system containing single and double impurities to an external
+exponential magnetic field at different degrees of anisotropy. We have
+demonstrated that the ergodicity of the system can be controlled by varying the
+strength and location of the impurities as well as the degree of anisotropy of
+the coupling.",1204.0759v1
+2012-04-06,Measurement of the elliptic anisotropy of charged particles produced in PbPb collisions at nucleon-nucleon center-of-mass energy = 2.76 TeV,"The anisotropy of the azimuthal distributions of charged particles produced
+in PbPb collisions with a nucleon-nucleon center-of-mass energy of 2.76 TeV is
+studied with the CMS experiment at the LHC. The elliptic anisotropy parameter
+defined as the second coefficient in a Fourier expansion of the particle
+invariant yields, is extracted using the event-plane method, two- and
+four-particle cumulants, and Lee--Yang zeros. The anisotropy is presented as a
+function of transverse momentum (pt), pseudorapidity (eta) over a broad
+kinematic range: 0.3 < pt < 20 GeV, abs(eta) < 2.4, and in 12 classes of
+collision centrality from 0 to 80%. The results are compared to those obtained
+at lower center-of-mass energies, and various scaling behaviors are examined.
+When scaled by the geometric eccentricity of the collision zone, the elliptic
+anisotropy is found to obey a universal scaling with the transverse particle
+density for different collision systems and center-of-mass energies.",1204.1409v2
+2012-05-08,Asymmetric velocity anisotropies in remnants of collisionless mergers,"Dark matter haloes in cosmological N-body simulations are affected by
+processes such as mergers, accretion and the gravitational interaction with
+baryonic matter. Typically the analysis of dark matter haloes is performed in
+spherical or elliptical bins and the velocity distributions are often assumed
+to be constant within those bins. However, the velocity anisotropy, which
+describes differences between the radial and tangential velocity dispersion,
+has recently been show to have a strong dependence on direction in the triaxial
+halos formed in cosmological simulations. In this study we derive properties of
+particles in cones parallel or perpendicular to the collision axis of merger
+remnants. We find that the velocity anisotropy has a strong dependence on
+direction. The finding that the direction-dependence of the velocity anisotropy
+of a halo depends on the merger history, explains the existence of such trends
+in cosmological simulations. It also explains why a large diversity is seen in
+the velocity anisotropy profiles in the outer parts of high-resolution
+simulations of cosmological haloes.",1205.1799v2
+2012-05-17,Anisotropy of TeV and PeV cosmic rays with IceCube and IceTop,"The interaction of high energy cosmic rays with the Earth's atmosphere
+produces extensive air showers of secondary particles with a large muon
+component. By exploiting the sensitivity of neutrino telescopes to high energy
+muons, it is possible to use these detectors for precision cosmic ray studies.
+The high rate of cosmic-ray muon events provides a high-statistics data sample
+that can be used to look for anisotropy in the arrival directions of the parent
+particles at the per-mille level.
+  This paper reports on the observation of anisotropy in the cosmic ray data
+collected with the IceCube neutrino telescope in the 20-400 TeV energy range at
+multiple angular scales. New data from the IceTop air shower array, located on
+the ice surface above IceCube, shows an anisotropy that is consistent with the
+high-energy IceCube results. The sensitivity of IceTop to all the components of
+the extensive air shower will allow us to explore in more detail the
+characteristics of the primary cosmic rays associated with the observed
+anisotropy.",1205.3969v1
+2012-05-23,On the Accuracy of Anisotropic Fast Marching,"The fast marching algorithm, and its variants, solves numerically the
+generalized eikonal equation associated to an underlying riemannian metric. A
+major challenge for these algorithms is the non-isotropy of the riemannian
+metric. Applications of the eikonal equation to image processing often involve
+pronounced anisotropies, which motivated the design of new algorithms.
+  A recently introduced variant of the fast marching algorithm addresses the
+problem of large anisotropies using an algebraic tool named lattice basis
+reduction. The numerical complexity of this algorithm is insensitive to
+anisotropy, under weak assumptions. We establish in this paper, in the
+simplified setting of a constant riemannian metric, that the accuracy of this
+algorithm is also extremely robust to anisotropy : in an average sense, it is
+independent of the anisotropy ratio. We also extend this algorithm to higher
+dimension.",1205.5300v1
+2012-07-06,Ferromagnetic Quantum critical behavior in three-dimensional Hubbard model with transverse anisotropy,"One-band Hubbard model with transverse anisotropy is considered at density of
+electrons $n=0.4$. It is shown that when the anisotropy is appropriately
+chosen, the ground state is ferromagnetic with magnetic order perpendicular to
+the anisotropy. The increasing of the ratio $\frac tU$, where $t$ is the
+hopping parameter and $U$ is the Coulomb repulsion, decreases the Curie
+temperature, and the system arrives at the quantum critical point $(T_C=0)$.
+The result is obtained introducing Schwinger bosons and slave Fermions
+representation of the electron operators. Integrating out the spin-singlet
+Fermi fields an effective Heisenberg model with ferromagnetic exchange constant
+is obtained for vectors which identifies the local orientation of the spin of
+the itinerant electrons. The amplitude of the spin vectors is an effective spin
+of the itinerant electrons accounting for the fact that some sites, in the
+ground state, are doubly occupied or empty. Owing to the anisotropy, the magnon
+fluctuations drive the system to quantum criticality and when the effective
+spin is critically small these fluctuations suppress the magnetic order.",1207.1674v1
+2013-01-10,Spectrum and Anisotropy of Cosmic Rays at TeV-PeV-energies and Contribution of Nearby Sources,"The role of nearby galactic sources, the supernova remnants, in formation of
+observed energy spectrum and anisotropy of high-energy cosmic rays is studied.
+The list of these sources is made up based on radio, X-ray and gamma-ray
+catalogues. The distant sources are treated statistically as ensemble of
+sources with random positions and ages. The source spectra are defined based on
+the modern theory of cosmic ray acceleration in supernova remnants while the
+propagation of cosmic rays in the interstellar medium is described in the
+frameworks of galactic diffusion model. Calculations of anisotropy are made to
+reproduce the experimental procedure of getting the two-dimensional anisotropy.
+The detailed comparison of calculations with cosmic ray data is made. We
+explained simultaneously the new cosmic ray data on a fine structure of all
+particle spectra around the knee and the amplitude and direction of the dipole
+component of anisotropy in the wide energy range 1 TeV - 1 EeV. Made
+assumptions do not look exotic, and they confirm the modern understanding of
+cosmic ray origin.",1301.2028v2
+2013-01-20,Anisotropy in a Nonsingular Bounce,"Following recent claims relative to the question of large anisotropy
+production in regular bouncing scenarios, we study the evolution of such
+anisotropies in a model where an Ekpyrotic phase of contraction is followed by
+domination of a Galileon-type Lagrangian which generates a non-singular bounce.
+We show that the anisotropies decrease during the phase of Ekpyrotic
+contraction (as expected) and that they can be constrained to remain small
+during the non-singular bounce phase (a non-trivial result). Specifically, we
+derive the e-folding number of the phase of Ekpyrotic contraction which leads
+to a present-day anisotropy in agreement with current observational bounds.",1301.4703v2
+2013-06-27,Amorphous GdFeCo Films Exhibiting Large and Tunable Perpendicular Magnetic Anisotropy,"We report the compositional and temperature dependence of magnetic
+compensation in amorphous GdFeCo films. Magnetic compensation is attributed to
+the competition between antiferromagnetic coupling of rare-earth with
+transition-metal (TM) ions and ferromagnetic interaction between the TM ions.
+The low-Gd region from 20 to 34 at. % was found to exhibit compensation
+phenomena characterized by a low saturation magnetization and perpendicular
+magnetic anisotropy (PMA) near the compensation temperature. Compensation
+temperature was not observed in previously unreported high-Gd region from 52 to
+59 at. %, in qualitative agreement with results from recent model calculations.
+However, low magnetization was achieved at room temperature, accompanied by a
+large PMA with coercivity reaching ~6.6 kOe. The observed perpendicular
+magnetic anisotropy of amorphous GdFeCo films probably has a structural origin
+consistent with certain aspects of the atomic-scale anisotropy. Our findings
+have broadened the composition range of transition metal-rare earth alloys for
+designing PMA films, making it attractive for tunable magnetic anisotropy in
+nanoscale devices.",1306.6451v1
+2013-07-01,Interplay between surface anisotropy and dipolar interactions in an assembly of nanomagnets,"We study the interplay between the effects of surface anisotropy and dipolar
+interactions in monodisperse assemblies of nanomagnets with oriented
+anisotropy. We derive asymptotic formulas for the assembly magnetization taking
+account of temperature, applied field, core and surface anisotropy, and dipolar
+inter-particle interactions. We find that the interplay between surface
+anisotropy and dipolar interactions is well described by the analytical
+expression of the assembly magnetization derived here: the overall sign of the
+product of the two parameters governing the surface and the dipolar
+contributions determines whether intrinsic and collective terms compete or have
+synergistic effects on the magnetization. This is illustrated by the
+magnetization curves of $\gamma-Fe_{2}O_{3}$ nanoparticles assemblies in the
+low concentration limit.",1307.0342v2
+2013-08-15,Shape-induced anisotropy in antiferromagnetic nanoparticles,"High fraction of the surface atoms considerably enhances the influence of
+size and shape on the magnetic and electronic properties of nanoparticles.
+Shape effects in ferromagnetic nanoparticles are well understood and allow to
+set and control the parameters of a sample that affect its magnetic anisotropy
+during production. In the present paper we study the shape effects in the other
+widely used magnetic materials -- antiferromagnets, -- which possess
+vanishingly small or zero macroscopic magnetization. We take into account the
+difference between the surface and bulk magnetic anisotropy of a nanoparticle
+and show that the effective magnetic anisotropy depends on the particle shape
+and crystallographic orientation of its faces. Corresponding shape-induced
+contribution to the magnetic anisotropy energy is proportional to the particle
+volume, depends on magnetostriction, and can cause formation of equilibrium
+domain structure. Crystallographic orientation of the nanoparticle surface
+determines the type of domain structure. The proposed model allows to predict
+the magnetic properties of antiferromagnetic nanoparticles depending on their
+shape and treatment.",1308.3327v1
+2013-09-04,On the Anisotropy of the Gravitational Wave Background from Massless Preheating,"When a light scalar field is present during inflation, its value will vary on
+superhorizon scales, modulating the preheating process at the end of inflation.
+Consequently, the amplitude of the gravitational wave (GW) background produced
+during preheating will also be modulated. The observed energy density of this
+background will therefore appear anisotropic at different angles in the sky. We
+provide a master formula for the angular power spectrum C_l of the anisotropies
+in the GW background from preheating, valid for any scenario where the
+anisotropies are due to the superhorizon modulation of a light degree of
+freedom. Using lattice field theory simulations of massless preheating with
+g^2/\lambda = 2, we find a flat angular spectrum l(l+1)C_l \approx 3x10^{-4},
+which represents a strong anisotropy of order 1% variations on large angular
+scales. For our choice of couplings, long wavelengths are amplified most
+strongly during parametric resonance, which is crucial for the development of
+the anisotropies. If future direct detection GW observatories are capable of
+detecting backgrounds of cosmological origin, they should be able to detect
+this effect. This could eventually become a powerful tool to discriminate among
+inflationary and preheating scenarios.",1309.1148v1
+2013-11-01,"Derivation of the anisotropy profile, constraints on the local velocity dispersion, and implications for direct detection","We study the implications of a pseudo-phase-space density power-law for the
+anisotropy profile of a Milky Way-like dark matter halo. Requiring that the
+anisotropy parameter does not take non-physical values within the virial radius
+places a maximum value on the local radial velocity dispersion. For a plausible
+range of halo parameters, it is possible to take a local total velocity
+dispersion of up to about $300\,\mathrm{km/s}$. Making this choice uniquely
+specifies the anisotropy and dispersion profiles. We introduce a way to model
+the local velocity distribution that incorporates this anisotropy and study the
+impact on direct detection.",1311.0256v3
+2013-11-05,Chiral skyrmions in cubic helimagnet films: the role of uniaxial anisotropy,"This paper reports on magnetometry and magnetoresistance measurements of MnSi
+epilayers performed in out-of-plane magnetic fields. We present a theoretical
+analysis of the chiral modulations that arise in confined cubic helimagnets
+where the uniaxial anisotropy axis and magnetic field are both out-of-plane. In
+contrast to in-plane field measurements (Wilson et al., Phys. Rev. B 86, 144420
+(2012)), the hard-axis uniaxial anisotropy in MnSi/Si(111) increases the energy
+of (111)-oriented skyrmions and in-plane helicoids relative to the cone phase,
+and makes the cone phase the only stable magnetic texture below the saturation
+field. While induced uniaxial anisotropy is important in stabilizing skyrmion
+lattices and helicoids in other confined cubic helimagnets, the particular
+anisotropy in MnSi/Si(111) entirely suppresses these states in an out-of-plane
+magnetic field. However, it is predicted that isolated skyrmions with enlarged
+sizes exist in MnSi/Si(111) epilayers in a broad range of out-of-plane magnetic
+fields.",1311.1191v2
+2013-12-09,Memory function approach to in-plane anisotropic resistivity in the antiferromagnetic phase of iron arsenide superconductors,"We theoretically examine anisotropy of in-plane resistivity in the striped
+antiferromagnetic phase of an iron arsenide superconductor by applying a memory
+function approach to the ordered phase with isotropic nonmagnetic impurity. We
+find that the anisotropy of the scattering rate is independent of carrier
+density when the topology of the Fermi surface is changed after the
+introduction of holes. On the other hand, the anisotropy of the Drude weight
+monotonically decreases reflecting the distortion of the Dirac Fermi surface
+and eventually leads to the reverse of anisotropy of resistivity, being
+consistent with experiment. The origin of the anisotropy is thus attributed to
+the interplay of impurity scattering and anisotropic electronic states.",1312.2322v3
+2013-12-13,Phase diagram of a three-dimensional antiferromagnet with random magnetic anisotropy,"Three-dimensional (3D) antiferromagnets with random magnetic anisotropy (RMA)
+experimentally studied to date do not have random single-ion anisotropies, but
+rather have competing two-dimensional and three-dimensional exchange
+interactions which can obscure the authentic effects of RMA. The magnetic phase
+diagram Fe$_{x}$Ni$_{1-x}$F$_{2}$ epitaxial thin films with true random
+single-ion anisotropy was deduced from magnetometry and neutron scattering
+measurements and analyzed using mean field theory. Regions with uniaxial,
+oblique and easy plane anisotropies were identified. A RMA-induced glass region
+was discovered where a Griffiths-like breakdown of long-range spin order
+occurs.",1312.3687v2
+2013-12-17,Control of the in-plane anisotropy in off-stoichiometric NiMnSb,"NiMnSb is a ferromagnetic half-metal which, because of its rich anisotropy
+and very low Gilbert damping, is a promising candidate for applications in
+information technologies. We have investigated the in-plane anisotropy
+properties of thin, MBE-grown NiMnSb films as a function of their Mn
+concentration. Using ferromagnetic resonance (FMR) to determine the uniaxial
+and four-fold anisotropy fields, 2KU/Ms and 2K1/Ms, we find that a small
+variation in composition is sufficient to change the film from primarily
+four-fold to primarily uniaxial behavior, allowing for continuous tuning of the
+anisotropy. This provides valuable flexibility in designing new device
+geometries.",1312.4781v2
+2014-02-24,Spiraling elliptic breathers in saturable nonlinear media with linear anisotropy,"We have introduced a class of spiraling elliptic breathers in saturable
+nonlinear media with linear anisotropy. Two kinds of evolution behaviors of the
+breathers, rotating and pendulum-like librating, are both predicted by the
+variational approach, and confirmed by the numerical simulation.The spiraling
+elliptic breathers can rotate even though they have no initial orbital angular
+momentum (OAM). Due to the linear anisotropy of the media, the OAM is no longer
+conserved. Therefore, the angular velocity is found to be not a constant but a
+periodic function of the propagation distance. When the linear anisotropy is
+large enough, the spiraling elliptic breathers can librate like the pendulum.
+The spiraling elliptic breathers exist in the media with not only the saturable
+nonlinearity but also the nonlocal nonlinearity, as a matter of fact, they are
+universal in the nonlinear media with the linear anisotropy.",1402.5736v1
+2014-03-10,Effective anisotropy gradient in pressure graded [Co/Pd] multilayers,"A vertically graded anisotropy profile has been proposed as an optimized
+balance of low coercivity and thermal stability for multilayers used in
+magnetic media. Deposition pressure is known to have a profound effect on the
+magnetic reversal properties of Co/Pd multilayers, making it an attractive
+control parameter for achieving an anisotropy gradient. We have used polarized
+neutron reflectometry to study the depth-dependent reversal behavior of
+""pressure-graded"" Co/Pd, and observed pronounced gradients in the saturation
+magnetization and in the rate at which magnetization changes with field (the
+effective anisotropy). While the anisotropy gradient likely arises from a
+combination of factors intrinsic to deposition pressure, micromagnetic
+simulations indicate that the observed saturation magnetization gradient alone
+has a major effect on the resulting coercivity.",1403.2126v2
+2014-03-19,Low anisotropy of the upper critical field in a strongly anisotropic layered cuprate: Evidence for paramagnetically limited superconductivity,"We study angular-dependent magnetoresistance in a low $T_c$ layered cuprate
+Bi$_{2.15}$Sr$_{1.9}$CuO$_{6+\delta}$. The low $T_c$ ~ 4 K allows complete
+suppression of superconductivity by modest magnetic fields and facilitate
+accurate analysis of the upper critical field $H_{c2}$. We observe an universal
+exponential decay of fluctuation conductivity in a broad range of temperatures
+above $T_c$ and propose a new method for extraction of $H_{c2}(T)$ from the
+scaling analysis of the fluctuation conductivity at $T>T_c$. Our main result is
+observation of a surprisingly low $H_{c2}$ anisotropy ~ 2, which is much
+smaller than the effective mass anisotropy of the material ~ 300. We show that
+the anisotropy is decreasing with increasing field and saturates at a small
+value when the field reaches the paramagnetic limit. We argue that the dramatic
+discrepancy of high field and low field anisotropies is a clear evidence for
+paramagnetically limited superconductivity.",1403.4817v2
+2014-03-25,Large-Scale Distribution of Arrival Directions of Cosmic Rays Detected at the Pierre Auger Observatory Above $10~$PeV,"Searches for large-scale anisotropies in the distribution of arrival
+directions of cosmic rays detected above $\simeq 10 $PeV at the Pierre Auger
+Observatory are presented. Although no significant deviation from isotropy is
+revealed at present, some of the measurements suggest that future data will
+provide hints for large-scale anisotropies over a wide energy range. Those
+anisotropies would have amplitudes which are too small to be significantly
+observed within the current statistics. Assuming that the cosmic ray anisotropy
+is dominated by dipole and quadrupole moments in the EeV-energy range, some
+consequences of the present upper limits on their amplitudes are presented.",1403.6314v1
+2014-04-14,Impurity induced enhancement of perpendicular magnetic anisotropy in Fe/MgO tunnel junctions,"Using first-principles calculations, we investigated the impact of chromium
+(Cr) and vanadium (V) impurities on the magnetic anisotropy and spin
+polarization in Fe/MgO magnetic tunnel junctions. It is demonstrated using
+layer resolved anisotropy calculation technique, that while the impurity near
+the interface has a drastic effect in decreasing the perpendicular magnetic
+anisotropy (PMA), its position within the bulk allows maintaining high surface
+PMA. Moreover, the effective magnetic anisotropy has a strong tendency to go
+from in-plane to out-of-plane character as a function of Cr and V concentration
+favoring out-of-plane magnetization direction for ~1.5 nm thick Fe layers at
+impurity concentrations above 20 %. At the same time, spin polarization is not
+affected and even enhanced in most situations favoring an increase of tunnel
+magnetoresistance (TMR) values.",1404.3523v1
+2014-05-19,Beyond the Ginzburg-Landau theory of freezing: Anisotropy of the interfacial free energy in the Phase-Field Crystal model,"This paper re-visits the weakly fourth order anisotropic Ginzburg-Landau (GL)
+theory of freezing. First we determine the anisotropy of the interfacial free
+energy in the Phase-Field Crystal (PFC) model analytically, and prove that it
+remains finite at the critical point as a direct consequence of the one-mode
+dominance of the model. Next, we derive the leading order PFC amplitude model
+and show the formal analogy to traditional weakly 4th order anisotropic GL
+theories. We conclude that the material-independent anisotropy appearing in
+emergent GL theory coincides with the remnant anisotropy of the generating PFC
+model. As a result, we show that the reduced temperature {\epsilon} does not
+enter into the interfacial free energy anisotropy for metallic materials in
+both the Phase-Field Crystal model and the emerging Ginzburg-Landau theories.
+Finally, we investigate the possible pathways of calibrating anisotropic
+Ginzburg-Landau theories.",1405.4680v1
+2014-06-08,Perpendicular magnetic anisotropy and magnetization process in CoFeB/Pd multilayer films,"Perpendicular magnetic anisotropy (PMA) and dynamic magnetization reversal
+process in [CoFeB $t$ nm/Pd 1.0 nm]$_n$ ($t$ = 0.4, 0.6, 0.8, 1.0, and 1.2 nm;
+$n$ = 2 - 20) multilayer films have been studied by means of magnetic
+hysteresis and Kerr effect measurements. Strong and controllable PMA with an
+effective uniaxial anisotropy up to 7.7$\times$ 10$^6$ J.m$^{-3}$ and a
+saturation magnetization as low as 200 emu/cc are achieved. Surface/interfacial
+anisotropy of CoFeB/Pd interfaces, the main contribution to the PMA, is
+separated from the effective uniaxial anisotropy of the films, and appears to
+increase with the number of the CoFeB/Pd bilayers. Observation of the magnetic
+domains during a magnetization reversal process using polar magneto-optical
+Kerr microscopy shows the detailed behavior of nucleation and displacement of
+the domain walls.",1406.2028v1
+2014-08-11,Hole spin dynamics and hole $g$ factor anisotropy in coupled quantum well systems,"Due to its p-like character, the valence band in GaAs-based heterostructures
+offers rich and complex spin-dependent phenomena. One manifestation is the
+large anisotropy of Zeeman spin splitting. Using undoped, coupled quantum wells
+(QWs), we examine this anisotropy by comparing the hole spin dynamics for high-
+and low-symmetry crystallographic orientations of the QWs. We directly measure
+the hole $g$ factor via time-resolved Kerr rotation, and for the low-symmetry
+crystallographic orientations (110) and (113a), we observe a large in-plane
+anisotropy of the hole $g$ factor, in good agreement with our theoretical
+calculations. Using resonant spin amplification, we also observe an anisotropy
+of the hole spin dephasing in the (110)-grown structure, indicating that
+crystal symmetry may be used to control hole spin dynamics.",1408.2360v1
+2014-10-01,Transverse anisotropy effects on spin-resolved transport through large-spin molecules,"The transport properties of a large-spin molecule strongly coupled to
+ferromagnetic leads in the presence of transverse magnetic anisotropy are
+studied theoretically. The relevant spectral functions, linear-response
+conductance and the tunnel magnetoresistance are calculated by means of the
+numerical renormalization group method. We study the dependence of transport
+characteristics on orbital level position, uniaxial and transverse
+anisotropies, external magnetic field and temperature. It is shown that while
+uniaxial magnetic anisotropy leads to the suppression of the Kondo effect,
+finite transverse anisotropy can restore the Kondo resonance. The effect of
+Kondo peak restoration strongly depends on the magnetic configuration of the
+device and leads to nontrivial behavior of the tunnel magnetoresistance. We
+show that the temperature dependence of the conductance at points where the
+restoration of the Kondo effect occurs is universal and shows a scaling typical
+for usual spin-one-half Kondo effect.",1410.0315v1
+2014-12-15,Antagonistic in-plane resistivity anisotropies from competing fluctuations in underdoped cuprates,"One of the prime manifestations of an anisotropic electronic state in
+underdoped cuprates is the in-plane resistivity anisotropy
+$\Delta\rho\equiv(\rho_{a}-\rho_{b})/\rho_{b}$. Here we use a
+Boltzmann-equation approach to compute the contribution to $\Delta\rho$ arising
+from scattering by anisotropic charge and spin fluctuations, which have been
+recently observed experimentally. While the anisotropy in the charge
+fluctuations is manifested in the correlation length, the anisotropy in the
+spin fluctuations emerges only in the structure factor. As a result, we find
+that spin fluctuations favor $\Delta\rho>0$, whereas charge fluctuations
+promote $\Delta\rho<0$, which are both consistent with the doping dependence of
+$\Delta\rho$ observed in YBa$_{2}$Cu$_{3}$O$_{7}$. We also discuss the role
+played by CuO chains in these materials, and propose transport experiments in
+strained HgBa$_{2}$CuO$_{4}$ and Nd$_{2}$CuO$_{4}$ to probe directly the
+different resistivity anisotropy regimes.",1412.4745v2
+2015-01-05,Magnetization of Quantum Dots: A Measure of Anisotropy and the Rashba Interaction,"The magnetization of anisotropic quantum dots in the presence of the Rashba
+spin-orbit interaction has been studied for three interacting electrons in the
+dot. We observe unique behaviors of magnetization that are direct reflections
+of the anisotropy and the spin-orbit interaction parameters independently or
+concurrently. In particular, there are saw-tooth structures in the magnetic
+field dependence of the magnetization, as caused by the electron-electron
+interaction, that are strongly modified in the presence of large anisotropy and
+high strength of the spin-orbit interactions. We report the temperature
+dependence of magnetization that indicates the temperature beyond which these
+structures due to the interactions disappear. Additionally, we found the
+emergence of a weak saw-tooth structure in magnetization in the high anisotropy
+and large spin-orbit interaction limit that was explained as a result of
+merging of two low-energy curves when the level spacings evolve with increasing
+values of the anisotropy and the spin-orbit interaction strength.",1501.01025v1
+2015-02-12,Effects of Interatomic Coupling on Magnetic Anisotropy and Order of Spins on Metallic Surfaces,"Both quantum and classical behavior of single atomic spins on surfaces is
+determined by the local anisotropy of adatoms and their coupling to the
+immediate electronic environment. Yet adatoms seldom reside on surfaces alone
+and it is generally acknowledged that substrated-mediated interactions can
+couple single spins among each other impacting their magnetic behavior. Here we
+show that also magnetic anisotropy, which is usually considered to be a
+constant determined by the local crystal field, can be extremely sensitive to
+such interactions. By the example of Co dimers on Cu(001) and Pt(001) surfaces
+we highlight the intricate interplay of exchange coupling and magnetic
+anisotropy providing a much sought possibility to tune the latter through
+deliberate adjustment of the adatoms' separation. As a technologically relevant
+implication we demonstrate the impact of such emergent non-local anisotropy on
+the hysterectic properties of single-atom magnetization curves.",1502.03743v2
+2015-02-27,Accurate calculation of the transverse anisotropy in perpendicularly magnetized multilayers,"The transverse anisotropy constant and the related D\""oring mass density are
+key parameters of the one-dimensional model to describe the motion of magnetic
+domain walls. So far, no general framework is available to determine these
+quantities from static characterizations such as magnetometry measurements.
+Here, we derive a universal analytical expression to calculate the transverse
+anisotropy constant for the important class of perpendicular magnetic
+multilayers. All the required input parameters of the model, such as the number
+of repeats, the thickness of a single magnetic layer, and the layer
+periodicity, as well as the effective perpendicular anisotropy, the saturation
+magnetization, and the static domain wall width are accessible by static sample
+characterizations. We apply our model to a widely used multilayer system and
+find that the effective transverse anisotropy constant is a factor 7 different
+from the when using the conventional approximations, showing the importance of
+using our analysis scheme.",1502.07937v1
+2015-05-13,Benefits of Carrier Pocket Anisotropy to Thermoelectric Performance: The case of $p$-type AgBiSe$_2$,"We study theoretically the effects of anisotropy on the thermoelectric
+performance of $p$-type AgBiSe$_2$. We present an apparent realization of the
+thermoelectric benefits of one-dimensional ""plate-like"" carrier pocket
+anisotropy in the valence band of this material. Based on first principles
+calculations we find a substantial anisotropy in the electronic structure,
+likely favorable for thermoelectric performance, in the valence bands of the
+hexagonal phase of the silver chalcogenide thermoelectric AgBiSe$_2$, while the
+conduction bands are more isotropic, and in our experiments do not attain high
+performance. AgBiSe$_2$ has already exhibited a $ZT$ value of 1.5 in a
+high-temperature disordered fcc phase, but room-temperature performance has not
+been demonstrated. We develop a theory for the ability of anisotropy to
+decouple the density-of-states and conductivity effective masses, pointing out
+the influence of this effect in the high performance thermoelectrics
+Bi$_2$Te$_3$ and PbTe. From our first principles and Boltzmann transport
+calculations we estimate the performance of $p$-type AgBiSe$_{2}$.",1505.03379v1
+2015-06-24,Implications of a temperature-dependent magnetic anisotropy for superparamagnetic switching,"The macroscopic magnetic moment of a superparamagnetic system has to overcome
+an energy barrier in order to switch its direction. This barrier is formed by
+magnetic anisotropies in the material and may be surmounted typically after
+10^9 to 10^12 attempts per second by thermal fluctuations. In a first step, the
+associated switching rate may be described by a Neel-Brown-Arrhenius law, in
+which the energy barrier is assumed as constant or a given temperature. Yet,
+magnetic anisotropies in general depend on temperature themselves which is
+known to modify the Neel-Brown-Arrhenius law. We illustrate quantitatively the
+implications of a temperature-dependent anisotropy on the switching rate and in
+particular for the interpretation of the prefactor as an attempt frequency. In
+particular, we show that realistic numbers for the attempt frequency are
+obtained when the temperature dependence of the anisotropy is taken into
+account.",1506.07333v2
+2015-06-24,Effects of anisotropy and disorder on the conductivity of Weyl semimetals,"We study dc conductivity of a Weyl semimetal with uniaxial anisotropy (Fermi
+velocity ratio $\xi= v_\bot/v_\parallel\neq1$) considering the scattering of
+charge carriers by a wide class of impurity potentials, both short- and
+long-range. We obtain the ratio of transverse and longitudinal (with respect to
+the anisotropy axis) conductivities as a function of both $\xi$ and
+temperature. We find that the transverse and longitudinal conductivities
+exhibit different temperature dependence in the case of short-range disorder.
+For general long-range disorder, the temperature dependence ($\sim T^4$) of the
+conductivity turns out to be insensitive of the anisotropy in the limits of
+strong ($\xi\gg$ and $\ll1$) and weak ($\xi\approx1$) anisotropy.",1506.07556v1
+2015-08-12,A Dzyaloshinskii-Moriya Anisotropy in Nanomagnets with in-plane Magnetization,"We report on a new source of in-plane anisotropy in nanomagnets due to the
+presence of Dzyaloshinskii-Moriya interaction (DMI). This anisotropy depends on
+the shape of the magnet, and is orthogonal to the demagnetization shape
+anisotropy. This effect originates from the DMI energy reduction due to an
+out-of-plane tilt of the spins at edges oriented perpendicular to the
+magnetization. Our investigation combining experimental, numerical and
+analytical results demonstrate that this energy reduction can compensate the
+demagnetization shape anisotropy energy in magnets of elongated shape, provided
+that their volumes is small enough and thus that their magnetization is
+quasi-uniform.",1508.02961v1
+2015-09-14,Thickness-Dependent Magnetoelasticity and its Effects on Perpendicular Magnetic Anisotropy in Ta|CoFeB|MgO Thin Films,"We report measurements of the in-plane magnetoelastic coupling in ultra-thin
+Ta|CoFeB|MgO layers as a function of uniaxial strain, conducted using a
+four-point bending apparatus. For annealed samples, we observe a strong
+dependence on the thickness of the CoFeB layer in the range 1.3-2.0 nm, which
+can be modeled as arising from a combination of effective surface and volume
+contributions to the magnetoelastic coupling. We point out that if similar
+thickness dependence exists for magnetoelastic coupling in response to biaxial
+strain, then the standard N\'eel model for the magnetic anisotropy energy
+acquires a term inversely proportional to the magnetic layer thickness. This
+contribution can significantly change the overall magnetic anisotropy, and
+provides a natural explanation for the strongly nonlinear dependence of
+magnetic anisotropy energy on magnetic layer thickness that is commonly
+observed for ultrathin annealed CoFeB|MgO films with perpendicular magnetic
+anisotropy.",1509.04134v1
+2015-10-14,Full-Sky Analysis of Cosmic-Ray Anisotropy with IceCube and HAWC,"During the past two decades, experiments in both the Northern and Southern
+hemispheres have observed a small but measurable energy-dependent sidereal
+anisotropy in the arrival direction distribution of galactic cosmic rays. The
+relative amplitude of the anisotropy is $10^{-4} - 10^{-3}$. However, each of
+these individual measurements is restricted by limited sky coverage, and so the
+pseudo-power spectrum of the anisotropy obtained from any one measurement
+displays a systematic correlation between different multipole modes $C_\ell$.
+To address this issue, we present the preliminary status of a joint analysis of
+the anisotropy on all angular scales using cosmic-ray data from the IceCube
+Neutrino Observatory located at the South Pole ($90^\circ$ S) and the
+High-Altitude Water Cherenkov (HAWC) Observatory located at Sierra Negra,
+Mexico ($19^\circ$ N). We describe the methods used to combine the IceCube and
+HAWC data, address the individual detector systematics and study the region of
+overlapping field of view between the two observatories.",1510.04134v2
+2015-11-09,Energy dependence of the spin excitation anisotropy in uniaxial-strained BaFe1.9Ni0.1As2,"We use inelastic neutron scattering to study the temperature and energy
+dependence of the spin excitation anisotropy in uniaxial-strained
+electron-doped iron pnictide BaFe$_{1.9}$Ni$_{0.1}$As$_2$ near optimal
+superconductivity ($T_c=20$ K). Our work has been motivated by the observation
+of in-plane resistivity anisotropy in the paramagnetic tetragonal phase of
+electron-underdoped iron pnictides under uniaxial pressure, which has been
+attributed to a spin-driven Ising-nematic state or orbital ordering. Here we
+show that the spin excitation anisotropy, a signature of the spin-driven
+Ising-nematic phase, exists for energies below $\sim$60 meV in
+uniaxial-strained BaFe$_{1.9}$Ni$_{0.1}$As$_2$. Since this energy scale is
+considerably larger than the energy splitting of the $d_{xz}$ and $d_{yz}$
+bands of uniaxial-strained Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ near optimal
+superconductivity, spin Ising-nematic correlations is likely the driving force
+for the resistivity anisotropy and associated electronic nematic correlations.",1511.02759v1
+2015-11-30,Small-scale anisotropies of cosmic rays from relative diffusion,"The arrival directions of multi-TeV cosmic rays show significant anisotropies
+at small angular scales. It has been argued that this small scale structure is
+reflecting the local, turbulent magnetic field in the presence of a global
+dipole anisotropy in cosmic rays as determined by diffusion. This effect is
+analogous to weak gravitational lensing of temperature fluctuations of the
+cosmic microwave background. We show that the non-trivial power spectrum in
+this setup can be related to the properties of relative diffusion and we study
+the convergence of the angular power spectrum to a steady-state as a function
+of backtracking time. We also determine the steady-state solution in an
+analytical approach based on a modified BGK ansatz. A rigorous mathematical
+treatment of the generation of small scale anisotropies will help in unraveling
+the structure of the local magnetic field through cosmic ray anisotropies.",1511.09451v1
+2015-12-21,Elliptic Anisotropy $v_2$ May Be Dominated by Particle Escape instead of Hydrodynamic Flow,"It is commonly believed that azimuthal anisotropies in relativistic heavy ion
+collisions are generated by hydrodynamic evolution of the strongly interacting
+quark-gluon plasma. Here we use transport models to study how azimuthal
+anisotropies depend on the number of collisions that each parton suffers. We
+find that the majority of $v_2$ comes from the anisotropic escape of partons,
+not from the parton collective flow, for semi-central Au+Au collisions at 200A
+GeV. As expected, the fraction of $v_2$ from the anisotropic particle escape is
+even higher for smaller systems such as d+Au. Our transport model results also
+confirm that azimuthal anisotropies would be dominated by hydrodynamic flow at
+unrealistically-high parton cross sections. Our finding thus naturally explains
+the similarity of azimuthal anisotropies in small and large systems; however,
+it presents a challenge to the paradigm of anisotropic flow.",1512.06465v1
+2015-12-22,Large Angular Scale CMB Anisotropy from an Excited Initial Mode,"According to inflationary cosmology, the CMB anisotropy gives an opportunity
+to test predictions of new physics hypotheses. The initial state of quantum
+fluctuations is one of the important options at high energy scale, as it can
+affect observables such as the CMB power spectrum. In this study a quasi-de
+Sitter inflationary background with approximate de Sitter mode function built
+over the Bunch-Davies mode is applied to investigate the scale-dependency of
+the CMB anisotropy. The recent Planck constraint on spectral index motivated us
+to examine the effect of a new excited mode function (instead of pure de Sitter
+mode) on the CMB anisotropy at large angular scales. In so doing, it is found
+that the angular scale-invariance in the CMB temperature fluctuations is broken
+and in the limit $ \ell<200 $ a tiny deviation appears. Also, it is shown that
+the power spectrum of CMB anisotropy is dependent on a free parameter with mass
+dimension $H<<M_{*}<M_{p}$ and on the slow-roll parameter $\epsilon $.",1512.07018v2
+2016-01-02,Field theory and anisotropy of cubic ferromagnet near Curie point,"Critical fluctuations are known to change the effective anisotropy of cubic
+ferromagnet near the Curie point. If the crystal undergoes phase transition
+into orthorhombic phase and the initial anisotropy is not too strong, effective
+anisotropy acquires at T_c the universal value A* = v*/u* where u* and v* are
+coordinates of the cubic fixed point entering the scaling equation of state and
+expressions for nonlinear susceptibilities. In the paper, the numerical value
+of the anisotropy parameter A at the critical point is estimated using the
+\epsilon-expansion and pseudo-\epsilon-expansion techniques. Pade resummation
+of six-loop pseudo-$\epsilon$-expansions for u*, v*, and A* leads to the
+estimate A* = 0.13 close to that extracted from the five-loop
+\epsilon-expansion but differing considerably from the value A* = 0.089 given
+by the analysis of six-loop expansions of the \beta-functions themselves. This
+discrepancy is discussed and its roots are cleared up.",1601.00147v2
+2016-02-10,Effects of electron temperature anisotropy on proton mirror instability evolution,"Proton mirror modes are large amplitude nonpropagating structures frequently
+observed in the magnetosheath. It has been suggested that electron temperature
+anisotropy can enhance the proton mirror instability growth rate while leaving
+the proton cyclotron instability largely unaffected, therefore causing the
+proton mirror instability to dominate the proton cyclotron instability in
+Earth's magnetosheath. Here, we use particle-in-cell simulations to investigate
+the electron temperature anisotropy effects on proton mirror instability
+evolution. Contrary to the hypothesis, electron temperature anisotropy leads to
+excitement of the electron whistler instability. Our results show that the
+electron whistler instability grows much faster than the proton mirror
+instability and quickly consumes the electron free energy, so that there is no
+electron temperature anisotropy left to significantly impact the evolution of
+the proton mirror instability.",1602.03411v1
+2016-02-22,Effect of transverse anisotropy on inelastic tunneling spectroscopy of atomic-scale magnetic chains,"We theoretically investigate the effect of transverse magnetic anisotropy on
+spin-flip assisted tunneling through atomic spin chains. Using a
+phenomenological approach and first-order perturbation theory, we analytically
+calculate the inelastic tunneling current, differential conductance and atomic
+spin transition rates. We predict the appearance of additional steps in the
+differential conductance and a pronounced increase in the spin-flip transition
+rate which at low voltages scale quadratically with the ratio of the transverse
+anisotropy energy and the sum of the longitudinal anisotropy energy and the
+exchange energy. Our results provide intuitive quantitative insight in the role
+played by transverse anisotropy in inelastic tunneling spectroscopy of atomic
+chains and can be observed under realistic experimental conditions.",1602.06839v2
+2016-02-29,Tunable magnetic anisotropy from higher-harmonics exchange scattering on the surface of a topological insulator,"We show that higher-harmonics exchange scattering from a magnetic adatom on
+the surface of a three dimensional topological insulator leads to a magnetic
+anisotropy whose magnitude and sign may be tuned by adjusting the chemical
+potential of the helical surface band. As chemical potential moves from the
+Dirac point towards the surface band edge, the surface normal is found to
+change from magnetic easy, to hard axis. Hexagonal warping is shown to diminish
+the region with easy axis anisotropy, and to suppress the anisotropy
+altogether. This indirect contribution can be comparable in magnitude to the
+intrinsic term arising from crystal field splitting and atomic spin-orbit
+coupling, and its tunability with chemical potential makes the two
+contributions experimentally discernible, and endows this source of anisotropy
+with potentially interesting magnetic functionality.",1602.08926v2
+2016-04-01,Anisotropies in the gravitational wave background as a probe of the cosmic string network,"Pulsar timing arrays are one of the powerful tools to test the existence of
+cosmic strings through searching for the gravitational wave background. The
+amplitude of the background connects to information on cosmic strings such as
+the tension and string network properties. In addition, one may be able to
+extract more information on properties of cosmic strings by measuring
+anisotropies in the gravitational wave (GW) background. In this paper, we
+provide estimates of the level of anisotropy expected in the GW background
+generated by cusps on cosmic strings. We find that the anisotropy level
+strongly depends on the initial loop size $\alpha$, and thus we may be able to
+put constraint on $\alpha$ by measuring the anisotropy of the GW background. We
+also find that certain regions of the parameter space can be probed by shifting
+the observation frequency of GWs.",1604.00332v2
+2016-04-04,"Imry-Ma disordered state induced by defects of ""random local anisotropy"" type in the system with O(n) symmetry","For the system with the n-component order parameter (O(n)-model), conditions
+for initiation of the Imry-Ma disordered state resulting from the influence of
+defects of the ""random local anisotropy"" type were discovered. The initiation
+of such a state was shown to be possible if the distribution of local
+anisotropy axes directions in the order parameter space is nearly isotropic,
+and the limiting degree of the distribution anisotropy was found. For a higher
+anisotropy in the distribution of local axes directions, the long-range order
+in the system holds true even in the presence of defects of the given type.",1604.00957v1
+2016-05-10,Grain size correlated rotatable magnetic anisotropy in polycrystalline exchange bias systems,"Angular resolved measurements of the exchange bias field and the coercive
+field are a powerful tool to distinguish between different competing magnetic
+anisotropies in polycrystalline exchange bias layer systems. No simple
+analytical model is as yet available, which considers time dependent effects
+like enhanced coercivity arising from the grain size distribution of the
+antiferromagnet. In this work we expand an existing model class describing
+polycrystalline exchange bias systems by a rotatable magnetic anisotropy term
+to describe grain size correlated effects. Additionally, we performed angular
+resolved magnetization curve measurements using vectorial magnetooptic Kerr
+magnetometry. Comparison of the experimental data with the proposed model shows
+excellent agreement and reveals the ferromagnetic anisotropy and properties
+connected to the grain size distribution of the antiferromagnet. Therefore, a
+distinction between the different influences on coercivity and anisotropy
+becomes available.",1605.02958v2
+2016-05-18,Chiral anomaly and giant magnetochiral anisotropy in noncentrosymmetric Weyl semimetals,"We theoretically propose that giant magnetochiral anisotropy is achieved in
+Weyl semimetals in noncentrosymmetric crystals as a consequence of the chiral
+anomaly. The magnetochiral anisotropy is the nonlinearity of the resistivity
+$\rho$ that depends on the current $\boldsymbol{I}$ and the magnetic field
+$\boldsymbol{B}$ as $\rho=\rho_0 (1 + \gamma \boldsymbol{I} \cdot
+\boldsymbol{B})$, and can be applied to rectifier devices controlled by
+$\boldsymbol{B}$. We derive the formula for the coefficient $\gamma$ in
+noncentrosymmetric Weyl semimetals. The obtained formula for $\gamma$ shows
+that the magnetochiral anisotropy is strongly enhanced when the chemical
+potential is tuned to Weyl points, and that noncentrosymmetric Weyl semimetals
+such as TaAs can exhibit much larger magnetochiral anisotropy than that
+observed in other materials so far.",1605.05409v2
+2016-07-01,Evolution of superconducting gap anisotropy in hole-doped 122 iron pnictides,"Motivated by recent experimental findings, we investigate the evolution of
+the superconducting gap anisotropy in 122 iron pnictides as a function of hole
+doping. Employing both a functional and a weak coupling renormalization group
+approach (FRG and WRG), we analyse the Fermi surface instabilities of an
+effective 122 model band structure at different hole dopings x, and derive the
+gap anisotropy from the leading superconducting instability. In the transition
+regime from collinear magnetism to s_{\pm}-wave, where strong correlations are
+present, we employ FRG to identify a non- monotonous change of the gap
+anisotropy in qualitative agreement with new experimental findings. From the
+WRG, which is asymptotically exact in the weak coupling limit, we find an
+s_{\pm}-wave to d-wave transition as a function of hole doping, complementing
+previous findings from FRG [Thomale et al., Phys. Rev. Lett. 107, 117001
+(2011)]. The gap anisotropy of the s_{\pm}-wave monotonously increases towards
+the transition to d-wave as a function of x.",1607.00412v1
+2016-08-18,The role of electron confinement in Pd films for the oscillatory magnetic anisotropy in an adjacent Co layer,"We demonstrate the interplay between quantum well states in Pd and the
+magnetic anisotropy in Pd/Co/Cu(001) by combined scanning tunneling
+spectroscopy (STS) and magneto optical Kerr effect (MOKE) measurements. Low
+temperature scanning tunneling spectroscopy reveals occupied and unoccupied
+quantum well states (QWS) in atomically flat Pd films on Co/Cu(001). These
+states give rise to sharp peaks in the differential conductance spectra. A
+quantitative analysis of the spectra reveals the electronic dispersion of the
+Pd(001) d-band ($\Delta$$_5$-type) along the $\Gamma$-X direction.
+\textit{In-situ} MOKE experiments on Pd/Co/Cu(1, 1, 13) uncover a periodic
+variation of the in-plane uniaxial magnetic anisotropy as a function of Pd
+thickness with a period of 6 atomic layers Pd. STS shows that QWS in Pd cross
+the Fermi level with the same periodicity of 6 atomic layers. Backed by
+previous theoretical work we ascribe the variation of the magnetic anisotropy
+in Co to QWS in the Pd overlayer. Our results suggest a novel venue towards
+tailoring uniaxial magnetic anisotropy of ferromagnetic films by exploiting QWS
+in an adjacent material with large spin-orbit coupling.",1608.05227v1
+2016-08-22,Quark self-energy in an ellipsoidally anisotropic quark-gluon plasma,"We calculate the quark self-energy in a quark-gluon plasma that possesses an
+ellipsoidal momentum-space anisotropy in the local rest frame. By introducing
+additional transverse momentum anisotropy parameters into the parton
+distribution functions, we generalize previous results which were obtained for
+the case of a spheroidal anisotropy. Our results demonstrate that the presence
+of anisotropies in the transverse directions affects the real and imaginary
+parts of quark self-energy and, consequently, the self-energy depends on both
+the polar and azimuthal angles in the local rest frame of the matter. Our
+results for the quark self-energy set the stage for the calculation of the
+effects of ellipsoidal momentum-space anisotropy on quark-gluon plasma photon
+spectra and collective flow.",1608.06018v1
+2016-09-07,Thermodynamics of anisotropic branes,"We study the thermodynamics of flavor D7-branes embedded in an anisotropic
+black brane solution of type IIB supergravity. The flavor branes undergo a
+phase transition between a `Minkowski embedding', in which they lie outside of
+the horizon, and a `black hole embedding', in which they fall into the horizon.
+This transition depends on the black hole temperature, its degree of
+anisotropy, and the mass of the flavor degrees of freedom. It happens either at
+a critical temperature or at a critical anisotropy. A general lesson we learn
+from this analysis is that the anisotropy, in this particular realization,
+induces similar effects as the temperature. In particular, increasing the
+anisotropy bends the branes more and more into the horizon. Moreover, we
+observe that the transition becomes smoother for higher anisotropies.",1609.02167v2
+2016-09-30,Precision ESR Measurements of Transverse Anisotropy in the Single-molecule Magnet Ni$_4$,"We present a method for precisely measuring the tunnel splitting in
+single-molecule magnets using electron-spin resonance, and use these
+measurements to precisely and independently determine the underlying transverse
+anisotropy parameter, given a certain class of transitions. By diluting samples
+of the SMM Ni$_4$ via co-crystallization in a diamagnetic isostructural
+analogue we obtain markedly narrower resonance peaks than are observed in
+undiluted samples. Using custom loop-gap resonators we measure the transitions
+at several frequencies, allowing a precise determination of the tunnel
+splitting. Because the transition under investigation occurs at zero field, and
+arises due to a first-order perturbation from the transverse anisotropy, we can
+determine the magnitude of this anisotropy independent of any other Hamiltonian
+parameters. This method can be applied to other SMMs with tunnel splittings
+arising from first-order transverse anisotropy perturbations.",1609.09859v2
+2016-10-14,Anisotropy of a Cubic Ferromagnet at Criticality,"Critical fluctuations change the effective anisotropy of cubic ferromagnet
+near the Curie point. If the crystal undergoes phase transition into
+orthorhombic phase and the initial anisotropy is not too strong, reduced
+anisotropy of nonlinear susceptibility acquires at $T_c$ the universal value
+$\delta_4^* = {{2v^*} \over {3(u^* + v^*)}}$ where $u^*$ and $v^*$ --
+coordinates of the cubic fixed point on the flow diagram of renormalization
+group equations. In the paper, the critical value of the reduced anisotropy is
+estimated within the pseudo-$\epsilon$ expansion approach. The six-loop
+pseudo-$\epsilon$ expansions for $u^*$, $v^*$, and $\delta_4^*$ are derived for
+the arbitrary spin dimensionality $n$. For cubic crystals ($n = 3$)
+higher-order coefficients of the pseudo-$\epsilon$ expansions obtained turn out
+to be so small that use of simple Pad\'e approximants yields reliable numerical
+results. Pad\'e resummation of the pseudo-$\epsilon$ series for $u^*$, $v^*$,
+and $\delta_4^*$ leads to the estimate $\delta_4^* = 0.079 \pm 0.006$
+indicating that detection of the anisotropic critical behavior of cubic
+ferromagnets in physical and computer experiments is certainly possible.",1610.04332v1
+2016-10-19,Large-Scale Cosmic-Ray Anisotropy as a Probe of Interstellar Turbulence,"We calculate the large-scale cosmic-ray (CR) anisotropies predicted for a
+range of Goldreich-Sridhar (GS) and isotropic models of interstellar
+turbulence, and compare them with IceTop data. In general, the predicted CR
+anisotropy is not a pure dipole; the cold spots reported at 400 TeV and 2 PeV
+are consistent with a GS model that contains a smooth deficit of
+parallel-propagating waves and a broad resonance function, though some other
+possibilities cannot, as yet, be ruled out. In particular, isotropic fast
+magnetosonic wave turbulence can match the observations at high energy, but
+cannot accommodate an energy dependence in the shape of the CR anisotropy. Our
+findings suggest that improved data on the large-scale CR anisotropy could
+provide a valuable probe of the properties - notably the power-spectrum - of
+the interstellar turbulence within a few tens of parsecs from Earth.",1610.06134v2
+2016-10-27,Evolution of CMB spectral distortion anisotropies and tests of primordial non-Gaussianity,"Anisotropies in distortions to the frequency spectrum of the cosmic microwave
+background (CMB) can be created through spatially varying heating processes in
+the early Universe. For instance, the dissipation of small-scale acoustic modes
+does create distortion anisotropies, in particular for non-Gaussian primordial
+perturbations. In this work, we derive approximations that allow describing the
+associated distortion field. We provide a systematic formulation of the problem
+using Fourier-space window functions, clarifying and generalizing previous
+approximations. Our expressions highlight the fact that the amplitudes of the
+spectral-distortion fluctuations induced by non-Gaussianity depend also on the
+homogeneous value of those distortions. Absolute measurements are thus required
+to obtain model-independent distortion constraints on primordial
+non-Gaussianity. We also include a simple description for the evolution of
+distortions through photon diffusion, showing that these corrections can
+usually be neglected. Our formulation provides a systematic framework for
+computing higher order correlation functions of distortions with CMB
+temperature anisotropies and can be extended to describe correlations with
+polarization anisotropies.",1610.08711v2
+2016-11-27,Theoretical study on the stimulated Brillouin scattering in a sub-wavelength anisotropic waveguide: Acousto-optical coupling coefficients and effects of transverse anisotropies,"A theoretical study on the stimulated Brillouin scattering (SBS) in a
+sub-wavelength anisotropic waveguide is conducted. The optical, photoelastic
+and mechanical anisotropies of the waveguide materials are all taken into
+account. First, the integral formulae for calculating the acousto-optical
+coupling coefficients (AOCCs) due to the photoelastic and moving interface
+effects in SBS are extended to an optically anisotropic waveguide. Then, with
+the extended formulae, the SBSs in an elliptical nanowire with strong
+transverse anisotropies are simulated. In the simulations, the elastic fields
+are computed with the inclusion of mechanical anisotropy. Observable effects of
+the strong transverse anisotropies are found in numerical results. Most
+notably, the SBS gains of some elastic modes are found to be very sensitive to
+the small misalignment between the waveguide axes and the principal material
+axes. Detailed physical interpretations of this interesting phenomenon are
+provided. This interesting phenomenon implies an attractive way for more
+sensitive tuning of the SBS gain without significantly changing the phononic
+frequency.",1611.08792v3
+2016-12-28,In-plane anisotropy of transport coefficients in the electronic nematic states: Universal origin of the nematicity in Fe-based superconductors,"The origin of the electronic nematicity and its remarkable
+material-dependence are famous longstanding unsolved issues in Fe-based
+superconductors. To attack these issues, we focus on the in-plane anisotropy of
+the resistivity: In the nematic state in FeSe, the relation $\rho_x>\rho_y$
+holds, where $\rho_{x(y)}$ is the resistivity along the longer (shorter) Fe-Fe
+axis. In contrast, the opposite anisotropy $\rho_x<\rho_y$ is realized in other
+undoped Fe-based superconductors. Such nontrivial material dependence is
+naturally explained in terms of the strongly orbital-dependent inelastic
+quasiparticle scattering realized in the orbital-ordered state. The opposite
+anisotropy between FeSe ($\rho_x>\rho_y$) and other undoped compounds
+($\rho_x<\rho_y$) reflects the difference in the number of hole-pockets. We
+also explain the large in-plane anisotropy of the thermoelectric power in the
+nematic state.",1612.08841v1
+2016-12-31,Enhancement of perpendicular magnetic anisotropy and its electric field-induced change through interface engineering in Cr/Fe/MgO,"Recently, perpendicular magnetic anisotropy (PMA) and its voltage control
+(VC) was demonstrated for Cr/Fe/MgO (Physical Review Applied 5, 044006 (2016)).
+In this study, we shed a light on the origin of large voltage-induced
+anisotropy change in Cr/Fe/MgO. Analysis of the chemical structure of Cr/Fe/MgO
+revealed the existence of Cr atoms in the proximity of the Fe/MgO interface,
+which can affect both magnetic anisotropy (MA) and its VC. We showed that PMA
+and its VC can be enhanced by controlled Cr doping at the Fe/MgO interface. For
+Cr/Fe (5.9 {\AA})/Cr (0.7 {\AA})/MgO with an effective PMA of 0.8 MJ/m3, a
+maximum value of the voltage-controlled magnetic anisotropy (VCMA) effect of
+370 fJ/Vm was demonstrated.",1701.00048v1
+2017-01-05,Anisotropies in GeV-TeV cosmic ray electrons and positrons,"High energy cosmic ray electrons and positrons probe the local properties of
+our Galaxy. In fact, electromagnetic energy losses limit the typical
+propagation scale of GeV-TeV electrons and positrons to a few kpc. In the
+diffusion model, nearby and dominant sources may produce an observable dipole
+anisotropy in the cosmic ray fluxes. We present a detailed study on the role of
+anisotropies from nearby sources in the interpretation of the observed GeV-TeV
+cosmic ray electron and positrons fluxes. We compute predictions for the
+anisotropies from known astrophysical sources as supernova remnants and pulsar
+wind nebulae of the ATNF catalog. Our results are compared with current
+anisotropy upper limits from the Fermi- LAT, AMS-02 and PAMELA experiments.",1701.01418v1
+2017-01-20,The Wavefunction of Anisotropic Inflationary Universes With No-Boundary Conditions,"We study the emergence of anisotropic (Bianchi IX) inflationary universes
+with no-boundary conditions in the path integral approach to quantum gravity.
+In contrast to previous work, we find no evidence for any limit to how large
+the anisotropies can become, although for increasing anisotropies the shape of
+the instantons becomes significantly different from Hawking's original
+no-boundary instanton. In all cases an inflationary phase is reached, with the
+anisotropies decaying away. Larger anisotropies are associated with a much
+larger imaginary part of the action, implying that the highly anisotropic
+branches of the wavefunction are heavily suppressed. Interestingly, the
+presence of anisotropies causes the wavefunction to become classical much more
+slowly than for isotropic inflationary universes. We derive the associated
+scaling of the WKB classicality conditions both numerically and analytically.",1701.05753v1
+2017-01-15,Anisotropic inflation in Brans-Dicke gravity,"We study anisotropic inflation in the Brans-Dicke gravity in the presence of
+an abelian gauge field where the gauge field is non-minimally coupled to the
+inflaton. We show that the degree of anisotropy, under slow-roll
+approximations, is proportional to slow roll parameter of the theory. As
+demonstration, we consider the displaced quadratic potential for the inflation.
+We do the numerical calculation of the model to investigate the behavior of
+anisotropy by changing the parameter in the Brans-Dicke model. We find out
+that, the solution is an attractor in the phase space, and anisotropy grows
+with number of e-folds. Anisotropy depends on Brans-Dicke parameter, $ \omega
+$, initial values of the scalar field and constant parameter of the coupling
+function of the scalar field and the abelian gauge field, $ c $. If we consider
+upper bound on the number of e-folds from CMB i.e. $ 60 $ e-folds, by
+increasing $ \omega $ and $ c $, anisotropy do not have time to exit the
+horizon and suppressed.",1701.06890v3
+2017-02-04,Direction-Dependent Stability of skyrmion lattice in helimagnets induced by Exchange Anisotropy,"Exchange anisotropy provides a direction dependent mechanism for the
+stability of the skyrmion lattice phase in noncentrosymmetric bulk chiral
+magnets. Based on the Fourier representation of the skyrmion lattice, we
+explain the direction dependence of the temperature-magnetic field phase
+diagram for bulk MnSi through a phenomenological mean-field model incorporating
+exchange anisotropy. Through quantitative comparison with experimental results,
+we clarify that the stability of the skyrmion lattice phase in bulk MnSi is
+determined by a combined effect of negative exchange anisotropy and thermal
+fluctuation. The effect of exchange anisotropy and the order of Fourier
+representation on the equilibrium properties of the skyrmion lattice is
+discussed in detail.",1702.01212v3
+2017-02-08,Spin-valley skyrmions in graphene at filling factor $ν=-1$,"We model quantum Hall skyrmions in graphene monolayer at quarter filling by a
+theory of CP3 fields and study the energy minimizing skyrmions in presence of
+valley pseudospin anisotropy and Zeeman coupling. We present a diagram of all
+types of skyrmions in a wide range of the anisotropy parameters. For each type
+of skyrmion, we visualize it on three Bloch spheres, and present the profiles
+of its texture on the graphene honeycomb lattice, thus providing references for
+the STM/STS imaging of spin-pseudospin textures in graphene monolayer in
+quantum Hall regime. Besides the spin and pseudospin skyrmions for the
+corresponding degrees of freedom of an electron in the N=0 Landau level, we
+discuss two unusual types -- the ""entanglement skyrmion"" whose texture lies in
+the space of the entanglement of spin and pseudospin, as well as the ""deflated
+pseudospin skyrmion"" with partial entanglement. For all skyrmion types, we
+study the dependence of the energy and the size of a skyrmion on the anisotropy
+parameters and perpendicular magnetic field. We also propose three ways to
+modify the anisotropy energy, namely the sample tilting, the substrate
+anisotropy and the valley pseudospin analogue of Zeeman coupling.",1702.02438v1
+2017-02-09,Gate Switchable Transport and Optical Anisotropy in 90° Twisted Bilayer Black Phosphorus,"Anisotropy describes the directional dependence of a material's properties
+such as transport and optical response. In conventional bulk materials,
+anisotropy is intrinsically related to the crystal structure, and thus not
+tunable by the gating techniques used in modern electronics. Here we show that,
+in bilayer black phosphorus with an interlayer twist angle of 90{\deg}, the
+anisotropy of its electronic structure and optical transitions is tunable by
+gating. Using first-principles calculations, we predict that a
+laboratory-accessible gate voltage can induce a hole effective mass that is 30
+times larger along one Cartesian axis than along the other axis, and the two
+axes can be exchanged by flipping the sign of the gate voltage. This
+gate-controllable band structure also leads to a switchable optical linear
+dichroism, where the polarization of the lowest-energy optical transitions
+(absorption or luminescence) is tunable by gating. Thus, anisotropy is a
+tunable degree of freedom in twisted bilayer black phosphorus.",1702.02679v1
+2017-02-20,Virtual photon polarization in ultrarelativistic heavy-ion collisions,"The polarization of direct photons produced in an ultrarelativistic heavy-ion
+collision reflects the momentum anisotropy of the quark-gluon plasma created in
+the collision. This paper presents a general framework, based on the photon
+spectral functions in the plasma, for analyzing the angular distribution and
+thus the polarization of dileptons in terms of the plasma momentum
+anisotropies. The rates of dilepton production depend, in general, on four
+independent spectral functions, corresponding to two transverse polarizations,
+one longitudinal polarization, and -- in plasmas in which the momentum
+anisotropy is not invariant under parity in the local rest frame of the matter
+-- a new spectral function, $\rho_n$, related to the anisotropy direction in
+the collision. The momentum anisotropy appears in the difference of the two
+transverse spectral functions, as well as in $\rho_n$. As an illustration, we
+delineate the spectral functions for dilepton pairs produced in the lowest
+order Drell-Yan process of quark-antiquark annihilation to a virtual photon.",1702.05906v1
+2017-02-25,Unveiling the role of Co-O-Mg bond in magnetic anisotropy of Pt/Co/MgO using atomically controlled deposition and in-situ electrical measurement,"Despite the crucial role of interfacial perpendicular magnetic anisotropy in
+Co(Fe)/MgO based magnetic tunnel junction, the underlying mechanism is still
+being debated. Here, we report an anatomical study of oxygen and Mg effect on
+Pt/Co bilayers through repeated in-situ anomalous Hall effect measurements,
+controlled oxygen exposure and Mg deposition in an ultrahigh vacuum system. We
+found that chemisorbed oxygen not only quenches the effective magnetic moment
+of the Co surface layer, but also softens its magnetic anisotropy. However, a
+subsequent Mg dusting on the oxygen pre-exposed Pt/Co surface can recover the
+magnetic anisotropy. The ab initio calculations on the exchange splitting and
+orbital hybridization near the Fermi level give a clear physical explanation of
+the experimental observations. Our results suggest that Co(Fe)-O-M bond plays a
+more important role than the widely perceived Co(Fe)-O bond does in realizing
+interfacial perpendicular magnetic anisotropy in Co(Fe)/MgO heterostructures.",1702.07852v1
+2017-03-03,Testing isotropy in the Two Micron All-Sky redshift survey with information entropy,"We use information entropy to test the isotropy in the nearby galaxy
+distribution mapped by the Two Micron All-Sky redshift survey (2MRS). We find
+that the galaxy distribution is highly anisotropic on small scales. The radial
+anisotropy gradually decreases with increasing length scales and the observed
+anisotropy is consistent with that expected for an isotropic Poisson
+distribution beyond a length scale of $90 \, h^{-1}\, {\rm Mpc}$. Using mock
+catalogues from N-body simulations, we find that the galaxy distribution in the
+2MRS exhibits a degree of anisotropy compatible with that of the $\Lambda$CDM
+model after accounting for the clustering bias of the 2MRS galaxies. We also
+quantify the polar and azimuthal anisotropies and identify two directions
+$(l,b)=(150^{\circ}, -15^{\circ})$, $(l,b)=(310^{\circ},-15^{\circ})$ which are
+significantly anisotropic compared to the other directions in the sky. We
+suggest that their preferential orientations on the sky may indicate a possible
+alignment of the Local Group with two nearby large scale structures. Despite
+the differences in the degree of anisotropy on small scales, we find that the
+galaxy distributions in both the 2MRS and the $\Lambda$CDM model are isotropic
+on a scale of $90 \, h^{-1}\, {\rm Mpc}$.",1703.01184v1
+2017-06-26,Spin excitation anisotropy in the paramagnetic tetragonal phase of BaFe2 As2,"We use neutron polarization analysis to study temperature dependence of the
+spin excitation anisotropy in BaFe$_2$As$_2$, which has a
+tetragonal-to-orthorhombic structural distortion at $T_s$ and antiferromagnetic
+(AF) phase transition at $T_N$ with ordered moments along the orthorhombic
+$a$-axis below $T_s\approx T_N\approx 136$ K. In the paramagnetic tetragonal
+state at 160 K, spin excitations are isotropic in spin space with
+$M_a=M_b=M_c$, where $M_a$, $M_b$, and $M_c$ are spin excitations polarized
+along the $a$, $b$, and $c$-axis directions of the orthorhombic lattice,
+respectively. On cooling towards $T_N$, significant spin excitation anisotropy
+with $M_a>M_b\approx M_c$ develops below 3 meV with a diverging $M_a$ at $T_N$.
+The in-plane spin excitation anisotropy in the tetragonal phase of
+BaFe$_2$As$_2$ is similar to those seen in the tetragonal phase of its electron
+and hole-doped superconductors, suggesting that spin excitation anisotropy is a
+direct probe of doping dependence of spin-orbit coupling and its connection to
+superconductivity in iron pnictides.",1706.08258v1
+2017-08-25,A Search for Cosmic-ray Proton Anisotropy with the Fermi Large Area Telescope,"In eight years of operation, the Fermi Large Area Telescope (LAT) has
+detected a large sample of cosmic-ray protons. The LAT's wide field of view and
+full-sky coverage make it an excellent instrument for studying anisotropy in
+the arrival directions of protons at all angular scales. These capabilities
+enable the LAT to make a full-sky 2D measurement of cosmic-ray proton
+anisotropy complementary to many recent TeV measurements, which are only
+sensitive to the right ascension component of the anisotropy. Any detected
+anisotropy probes the structure of the local interstellar magnetic field or
+could indicate the presence of a nearby source. We present the first results
+from the Fermi-LAT Collaboration on the full-sky angular power spectrum of
+protons from approximately 100 GeV - 10 TeV.",1708.07796v1
+2017-09-25,Dynamical vs geometric anisotropy in relativistic heavy-ion collisions: which one prevails?,"We study the influence of geometric and dynamical anisotropies on the
+development of flow harmonics and, simultaneously, on the second- and
+third-order oscillations of femtoscopy radii. The analysis is done within the
+Monte Carlo event generator HYDJET++, which was extended to dynamical
+triangular deformations. It is shown that the merely geometric anisotropy
+provides the results which anticorrelate with the experimental observations of
+either $v_2$ (or $v_3$) or second-order (or third-order) oscillations of the
+femtoscopy radii. Decays of resonances significantly increase the emitting
+areas but do not change the phases of the radii oscillations. In contrast to
+the spatial deformations, the dynamical anisotropy alone provides the correct
+qualitative description of the flow and the femtoscopy observables
+simultaneously. However, one needs both types of the anisotropy to match
+quantitatively the experimental data.",1709.08602v2
+2017-10-22,Nonlinear anisotropy growth in Bianchi-I spacetime in metric $f(R)$ cosmology,"The present work is related to anisotropic cosmological evolution in metric
+$f(R)$ theory of gravity. The initial part of the paper develops the general
+cosmological dynamics of homogeneous anisotropic Bianchi-I spacetime in $f(R)$
+cosmology. The anisotropic spacetime is pervaded by a barotropic fluid which
+has isotropic pressure. The paper predicts nonlinear growth of anisotropy in
+such spacetimes. In the later part of the paper we display the predictive power
+of the nonlinear differential equation responsible for the cosmological
+anisotropy growth in various relevant cases. We present the exact solutions of
+anisotropy growth in Starobinsky inflation driven by quadratic gravity and
+exponential gravity theory. Semi-analytical results are presented for the
+contraction phase in quadratic gravity bounce. The various examples of
+anisotropy growth in Bianchi-I model universe shows the complex nature of the
+problem at hand.",1710.07906v4
+2017-11-10,Impact of organic capping layer on the magnetic anisotropy of ultrathin Co films,"Using combined magnetometry and ferromagnetic resonance studies, it is shown
+that introduction of a hydrocarbon cover layer leads to an increase of the
+contribution of the surface anisotropy to the effective magnetic anisotropy
+energy of hexagonal close-packed 0001 cobalt films, largely enhancing the
+perpendicular anisotropy. Due to a weak electronic interaction of the organic
+molecules with the Co atoms, an increase of surface anisotropy could be
+explained by the presence of an electric field at the organic-material/Co
+interface and by modification of surface atoms charge configuration.",1711.03858v1
+2017-11-30,Magnetic anisotropy by Rashba spin-orbit coupling in antiferromagnetic thin films,"Magnetic anisotropy in an antiferromagnet (AFM) with inversion symmetry
+breaking (ISB) is investigated. The magnetic anisotropy energy (MAE) resulting
+from the Rashba spin-orbit and s-d type exchange interactions is determined for
+two different models of AFMs. The global ISB model, representing the effect of
+a surface, an interface, or a gating electric field, results in an easy-plane
+magnetic anisotropy. In contrast, for a local ISB model, i.e., for a
+noncentrosymmetric AFM, perpendicular magnetic anisotropy (PMA) arises. Both
+results differ from the ferromagnetic case, in which the result for PMA depends
+on the band structure and dimensionality. These MAE contributions play a key
+role in determining the direction of the Neel order parameter in
+antiferromagnetic nanostructures, and reflect the possibility of
+electrical-field control of the Neel vector.",1711.11184v2
+2017-12-13,Anisotropy and spin-fluctuation effects on the spectral properties of Shiba impurities,"We theoretically consider a quantum magnetic impurity coupled to a
+superconductor, and obtain the local density of states at the position of the
+impurity taking into account the effect of spin-fluctuations and single-ion
+magnetic anisotropy. We particularly focus on the spectrum of subgap
+Yu-Shiba-Rusinov (YSR or Shiba) states induced by a quantum impurity with easy-
+or hard-axis uniaxial anisotropy. Although this is a relevant experimental
+situation in, e.g., magnetic adatoms on the surface of clean metals, it is
+customary that theoretical descriptions assume a classical-spin approximation
+which is not able to account for single-ion anisotropy and other quantum
+effects. Here, quantum fluctuations of the spin are taken into account in the
+equations of motion of the electronic Green's function in the weak-coupling
+limit, and considerably modify the energy of the Shiba states compared to the
+classical-spin approximation. Our results point towards the importance of
+incorporating quantum fluctuations and anisotropy effects for the correct
+interpretation of scanning tunneling microscopy (STM) experiments.",1712.04920v2
+2017-12-23,Shape anisotropy revisited in single-digit nanometer magnetic tunnel junctions,"Nanoscale magnetic tunnel junction plays a pivotal role in magnetoresistive
+random access memories. Successful implementation depends on a simultaneous
+achievement of low switching current for the magnetization switching by
+spin-transfer torque and high thermal stability, along with a continuous
+reduction of junction size. Perpendicular-easy-axis CoFeB/MgO stacks possessing
+interfacial anisotropy have paved the way down to 20-nm scale, below which a
+new approach needs to be explored. Here we show magnetic tunnel junctions that
+satisfy the requirements at ultrafine scale by revisiting shape anisotropy,
+which is a classical part of magnetic anisotropy but has not been fully
+utilized in the current perpendicular systems. Magnetization switching solely
+driven by current is achieved for junctions smaller than 10 nm where sufficient
+thermal stability is provided by shape anisotropy without adopting new material
+systems. This work is expected to push forward the development of magnetic
+tunnel junctions towards single-digit-nm-scale nano-magnetics/spintronics.",1712.08774v1
+2018-01-04,Properties of polycrystalline nanoparticles with uniaxial and cubic types of magnetic anisotropy of individual grains,"The influence of the crystal structure inhomogeneities on the magnetic
+properties of cobalt nanoparticles with different aspect ratio and spherical
+nanoparticles of chromium dioxide, cobalt ferrite and magnetite has been
+studied by means of numerical simulation. The polycrystalline nanoparticles are
+modeled by means of subdivision of the nanoparticle volume into tightly bound
+single-crystal granules with randomly distributed directions of the easy
+anisotropy axes. The probability of appearance of quasi uniform and vortex
+states in sufficiently large assemblies of polycrystalline nanoparticles of
+various types have been calculated depending on the nanoparticle diameter. It
+is shown that the subdivision of a nanoparticle into single-crystal granules
+with different orientations of the easy anisotropy axes substantially reduces
+the effective single-domain diameters for particles with uniaxial type of
+anisotropy of individual granules. However, for particles with cubic type of
+magnetic anisotropy the influence of the crystal structure inhomogeneities on
+the equilibrium properties of the particles is not so important even for
+magnetically hard cobalt ferrite nanoparticles. It is practically absent for
+magnetically soft magnetite nanoparticles.",1801.01266v1
+2018-01-11,General relativistic polytropes in anisotropic stars,"Spherically symmetric relativistic stars with the polytropic equation of
+state (EoS), which possess the local pressure anisotropy, are considered within
+the framework of general relativity. The generalized Lane-Emden equations are
+derived for the arbitrary anisotropy parameter $\Delta=p_t-p_r$ ($p_t$ and
+$p_r$ being the transverse and radial pressure, respectively). They are then
+applied to some special ansatz for the anisotropy parameter in the form of the
+differential relation between the anisotropy parameter $\Delta$ and the metric
+function $\nu$. The analytical solutions of the obtained equations are found
+for incompressible fluid stars and then used for getting their mass-radius
+relation, gravitational and binding energy. Also, following the Chandrasekhar
+variational approach, the dynamical stability of incompressible anisotropic
+fluid stars with the polytropic EoS against radial oscillations is studied. It
+is shown that the local pressure anisotropy with $p_t>p_r$ can make the
+incompressible fluid stars unstable with respect to radial oscillations, in
+contrast to incompressible isotropic fluid stars with the polytropic EoS which
+are dynamically stable.",1801.03745v1
+2018-01-13,Quantum phase transitions in spin-1 XXZ chains with rhombic single-ion anisotropy,"We explore the fidelity susceptibility and the quantum coherence along with
+the entanglement entropy in the ground-state of one-dimensional spin-1 XXZ
+chains with the rhombic single-ion anisotropy. By using the techniques of
+density matrix renormalization group, effects of the rhombic single-ion
+anisotropy on a few information theoretical measures are investigated, such as
+the fidelity susceptibility, the quantum coherence and the entanglement
+entropy. Their relations with the quantum phase transitions are also analyzed.
+The phase transitions from the Y-N\'{e}el phase to the Large-$E_x$ or the
+Haldane phase can be well characterized by the fidelity susceptibility. The
+second-order derivative of the ground-state energy indicates all the
+transitions are of second order. We also find that the quantum coherence, the
+entanglement entropy, the Schmidt gap can be used to detect the critical points
+of quantum phase transitions. Conclusions drawn from these quantum information
+observables agree well with each other. Finally we provide a ground-state phase
+diagram as functions of the exchange anisotropy $\Delta$ and the rhombic
+single-ion anisotropy $E$.",1801.04922v2
+2018-01-31,Polarization and dilepton angular distribution in pion-nucleon collisions,"We study hadronic polarization and the related anisotropy of the dilepton
+angular distribution for the reaction $\pi N \to Ne^+e^-$. We employ consistent
+effective interactions for baryon resonances up to spin-5/2 to compute their
+contribution to the anisotropy coefficient. We show that the spin and parity of
+the intermediate baryon resonance is reflected in the angular dependence of the
+anisotropy coefficient. We present results for the anisotropy coefficient
+including the $N(1520)$ and $N(1440)$ resonances, which are essential at the
+collision energy of the recent data obtained by the HADES collaboration on this
+reaction. We conclude that the anisotropy coefficient provides useful
+constraints for unraveling the resonance contributions to this process.",1802.00062v1
+2018-03-05,Reconstruction method of $f(R)$ gravity for isotropic and anisotropic spacetimes,"We present the reconstruction method of $f(R)$ gravity for the homogeneous
+and anisotropic Bianchi-I spacetime, which was previously formulated only for
+homogeneous and isotropic FLRW spacetime. We argue in this paper that for
+anisotropic spacetimes, the total anisotropy behaves as an independent metric
+degree of freedom on top of the average scale factor in $f(R)$ gravity. This is
+not like $GR$, where specifying the form of the average scale factor as a
+function of time also specify the total anisotropy as a function of time
+uniqely. We link this peculiar fact to an interesting intertwining between the
+definition of Ricci scalar for anisotropic metric and anisotropy evolution
+equation in $f(R)$ gravity. Consequently, specifying an anisotropic solution of
+$f(R)$ gravity implies specifying both the average scale factor and the total
+anisotropy as functions of time. The reconstruction method hence formulated is
+applied to two scenarios where anisotropy suppression is important, namely, a
+quasi de-Sitter expansion as required in inflation, and a power law contraction
+as required in ekpyrotic bounce models.",1803.01594v2
+2018-03-22,Searching for a possible dipole anisotropy on acceleration scale with 147 rotationally supported galaxies,"We report a possible dipole anisotropy on acceleration scale $g_{\dag}$ with
+147 rotationally supported galaxies in local Universe. It is found that a
+monopole and dipole correction for the radial acceleration relation can better
+describe the SPARC data set. The monopole term is negligible but the dipole
+magnitude is significant. It is also found that the dipole correction is mostly
+induced by the anisotropy on the acceleration scale. The magnitude of
+$\hat{g}_{\dag}$-dipole reaches up to $0.25\pm0.04$, and its direction is
+aligned to $(l,b) = (171.30^{\circ}\pm7.18^{\circ},
+-15.41^{\circ}\pm4.87^{\circ})$, which is very close to the maximum anisotropy
+direction from the hemisphere comparison method. Furthermore, robust check
+shows that the dipole anisotropy couldn't be reproduced by isotropic mock data
+set. However, it is still premature to claim that the Universe is anisotropic
+due to the small data samples and uncertainty in the current observations.",1803.08344v2
+2018-05-03,Symmetry broken spin reorientation transition in epitaxial MgO/Fe/MgO layers with competing anisotropies,"The observation of perpendicular magnetic anisotropy (PMA) at MgO/Fe
+interfaces boosted the development of spintronic devices based on ultrathin
+ferromagnetic layers. Yet, magnetization reversal in the standard magnetic
+tunnel junctions (MTJs) with competing PMA and in-plane anisotropies remains
+unclear. Here we report on the field induced nonvolatile broken symmetry
+magnetization reorientation transition from the in-plane to the perpendicular
+(out of plane) state at temperatures below 50K. The samples were 10 nm thick Fe
+in MgO/Fe(100)/MgO as stacking components of V/MgO/Fe/MgO/Fe/Co double barrier
+MTJs. Micromagnetic simulations with PMA and different second order
+anisotropies at the opposite Fe/MgO interfaces qualitatively reproduce the
+observed broken symmetry spin reorientation transition. Our findings open the
+possibilities to develop multistate epitaxial spintronics based on competing
+magnetic anisotropies.",1805.01304v2
+2018-05-22,Thermoelectric anisotropy in Ba(Fe1-xCox)2As2 iron-based superconductor,"We report the in-plane anisotropy of the Seebeck and Nernst coefficients as
+well as of the electrical resistivity determined for the series of the
+strain-detwinned single crystals of Ba(Fe1-xCox)2As2. Two underdoped samples (x
+= 0.024, 0.045) exhibiting the transition from the tetragonal paramagnetic
+phase to the orthorhombic spin density wave (SDW) phase (at Ttr = 100 and 60 K,
+respectively) show an onset of the Nernst anisotropy at temperatures above 200
+K, which is significantly higher than Ttr. In the optimally doped sample (x =
+0.06) the transport properties also appear to be in-plane anisotropic below T =
+120 K, despite the fact that this particular composition does not show any
+evidence of long-range magnetic order. However, the anisotropy observed in the
+optimally doped crystal is rather small and for the Seebeck and Nernst
+coefficients the difference between values measured along and across the
+uniaxial strain has opposite sign to those observed for underdoped crystals
+with x = 0.024 and 0.045. For these two samples, insensitivity of the Nernst
+anisotropy to the SDW transition suggests that the nematicity might be of other
+than magnetic origin.",1805.08510v1
+2018-05-23,Testing the anisotropy of cosmic acceleration from Pantheon supernovae sample,"In this paper, we study the anisotropy of cosmic acceleration the using
+Pantheon sample, which includes 1048 spectroscopically confirmed Type Ia
+supernovae (SNe Ia) covering the redshift range $0.01 < z < 2.3$. In hemisphere
+comparison method, we find the dipole direction is $(l = 37 \pm 40^{\circ}, b =
+33 \pm 16^{\circ})$ with the maximum anisotropy level of $\delta=0.136
+{}^{+0.009}_{-0.005}$. From the dipole fitting method, we find that the
+magnitude of anisotropy is $A = (3.7 {}^{+2.5}_{-3.7}) \times 10^{-4}$, and the
+direction of the dipole $(l = 329^{\circ}{}^{+ 101^{\circ}}_{-28^{\circ}}, b =
+37^{\circ}{}^{+ 52^{\circ}}_{-21^{\circ}})$ in the galactic coordinate system.
+The result is weakly dependent on redshift from the redshift tomography
+analysis. The anisotropy is small and the isotropic cosmological model is an
+excellent approximation.",1805.09195v2
+2018-06-18,Current-driven domain wall motion along ferromagnetic strips with periodically-modulated perpendicular anisotropy,"The dynamics of magnetic domain walls along ferromagnetic strips with
+spatially modulated perpendicular magnetic anisotropy is theoretically studied
+by means of micromagnetic simulations. Ferromagnetic layers with a periodic
+sawtooth profile of the anisotropy depict a well-defined set of energy minima
+where the walls are pinned in the absence of external stimuli, and favor the
+unidirectional propagation of domain walls. The performance of the
+current-driven domain wall motion along these ratchet-like systems is compared
+to the field-driven case. Our study indicates that the current-driven domain
+wall motion exhibits significant improvements with respect to the field-driven
+case in terms of bit shifting speed and storage density, and therefore, it is
+suggested for the development of novel devices. The feasibility of these
+current-driven ratchet devices is studied by means of realistic micromagnetic
+simulations and supported by a one-dimensional model updated to take into
+account the periodic sawthooth anisotropy profile. Finally, the current-driven
+domain wall motion is also evaluated in systems with a triangular modulation of
+the anisotropy designed to promote the bidirectional shifting of series of
+walls, a functionality that cannot be achieved by magnetic fields.",1806.06585v1
+2018-07-09,Engineering Phonon Polaritons in van der Waals Heterostructures to Enhance In-Plane Optical Anisotropy,"Van der Waals heterostructures assembled from layers of 2D materials have
+attracted considerable interest due to their novel optical and electrical
+properties. Here we report a scattering-type scanning near field optical
+microscopy study of hexagonal boron nitride on black phosphorous (h-BN/BP)
+heterostructures, demonstrating the first direct observation of in-plane
+anisotropic phonon polariton modes in vdW heterostructures. Strikingly, the
+measured in-plane optical anisotropy along armchair and zigzag crystal axes
+exceeds the ratio of refractive indices of BP in the x-y plane. We explain that
+this enhancement is due to the high confinement of the phonon polaritons in
+h-BN. We observe a maximum in-plane optical anisotropy of {\alpha}_max=1.25 in
+the 1405-1440 cm-1 frequency spectrum. These results provide new insights on
+the behavior of polaritons in vdW heterostructures, and the observed anisotropy
+enhancement paves the way to novel nanophotonic devices and to a new way to
+characterize optical anisotropy in thin films.",1807.03339v1
+2018-08-29,On the effect of turbulent anisotropy on pulsation stability of stars,"Within the framework of non-local time-dependent stellar convection theory,
+we study in detail the effect of turbulent anisotropy on stellar pulsation
+stability. The results show that anisotropy has no substantial influence on
+pulsation stability of g modes and low-order (radial order $n_\mathrm{r}<5$) p
+modes. The effect of turbulent anisotropy increases as the radial order
+increases. When turbulent anisotropy is neglected, most of high-order
+($n_\mathrm{r}>5$) p modes of all low-temperature stars become unstable.
+Fortunately, within a wide range of the anisotropic parameter $c_3$, stellar
+pulsation stability is not sensitive to the specific value of $c_3$. Therefore
+it is safe to say that calibration errors of the convective parameter $c_3$ do
+not cause any uncertainty in the calculation of stellar pulsation stability.",1808.09625v1
+2018-09-19,Large phase-transition-induced magnetic anisotropy change in (Co/Pt)2/VO2 heterostructure,"We report the phase-transition controlled magnetic anisotropy modulation in
+the (Co/Pt)2/VO2 heterostructure, where VO2 is introduced into the system to
+applied an interfacial strain by its metal-insulator transition. A large
+reversible modulation of the perpendicular magnetic anisotropy (PMA) reaching
+38 kJ/m3 is observed during this process. The calculated energy density
+variation of interfacial anisotropy reaches 100 mJ/m2, which shows significant
+advantage over traditional modulation strategies. Further experimental results
+including magnetization change versus temperature, strain buffered modulation
+and pre-strained sample comparison prove that the interfacial coupling between
+VO2 and PMA layers plays a crucial role in this modulation. This work,
+demonstrating the great potential of phase-transition material in efficient
+magnetic anisotropy modulation, would benefit the exploration for low-power
+consumption devices.",1809.06999v1
+2018-09-29,Perpendicular magnetic anisotropy in bulk and thin-film CuMnAs for antiferromagnetic memory applications,"CuMnAs with perpendicular magnetic anisotropy is proposed as an active
+material for antiferromagnetic memory. Information can be stored in the
+antiferromagnetic domain state, while writing and readout can rely on the
+existence of the surface magnetization. It is predicted, based on
+first-principles calculations, that easy-axis anisotropy can be achieved in
+bulk CuMnAs by substituting a few percent of As atoms by Ge, Si, Al, or B. This
+effect is attributed to the changing occupation of certain electronic bands
+near the Fermi level induced by the hole doping. The calculated temperature
+dependence of the magnetic anisotropy does not exhibit any anomalies. Thin
+CuMnAs(001) films are also predicted to have perpendicular magnetic anisotropy.",1810.00249v1
+2018-10-09,Statistical anisotropy in CMB spectral distortions,"Measurements of the cosmic microwave background (CMB) spectral $y$-distortion
+anisotropy offer a test for the statistical isotropy of the primordial density
+perturbations on $0.01\lesssim k{\rm Mpc}\lesssim 1$. We compute the 1-point
+ensemble averages of the $y$-distortion anisotropies which vanish for the
+statistically isotropic perturbations. For the quadrupole statistical
+anisotropy, we find $4\pi\langle y_{2m}\rangle=-6.8A_2\times
+10^{-9}Y_{2m}(\mathbf d )$ with the quadruple Legendre coefficient of the
+anisotropic powerspectrum $A_2$ and the $\ell=2$ spherical harmonics
+$Y_{2m}(\mathbf d )$ for the preferred direction $\mathbf d $. Also, we discuss
+the cosmic variance of the $y$-distortion anisotropy in the statistically
+anisotropic Universe.",1810.03928v2
+2018-10-31,Visualizing Intramolecular Distortions as the Origin of Transverse Magnetic Anisotropy,"The magnetic properties of metal-organic complexes are strongly influenced by
+conformational changes in the ligand. The flexibility of
+Fe-tetra-pyridyl-porphyrin molecules leads to different adsorption
+configurations on a Au(111) surface. By combining low-temperature scanning
+tunneling spectroscopy and atomic force microscopy, we resolve a correlation of
+the molecular configuration with different spin states and magnitudes of
+magnetic anisotropy. When the macrocycle exhibits a laterally-undistorted
+saddle shape, the molecules lie in a S=1 state with axial anisotropy arising
+from a square-planar ligand field. If the symmetry in the molecular ligand
+field is reduced by a lateral distortion of the molecule, we find a finite
+contribution of transverse anisotropy. Some of the distorted molecules lie in a
+S=2 state, again exhibiting substantial transverse anisotropy.",1811.00059v1
+2018-11-19,Small Anisotropy in Stellar Objects in Modified Theories of Gravity,"Interior structures of stellar objects might have small pressure anisotropy
+due to several reasons, including rotation and the presence of magnetic fields.
+Here, retaining the approximation of spherical symmetry, we study the possible
+role of small anisotropy in stellar interiors in theories of modified gravity,
+that are known to alter the hydrostatic equilibrium condition inside stars. We
+show how anisotropy may put lower and upper bounds on the modified gravity
+parameter depending on the polytropic equation of state, and determine them
+numerically. We also study the mass of stellar objects in these theories,
+assuming such equations of state, and find that the Chandrasekhar mass limit in
+white dwarf stars gets substantially modified compared to the isotropic case,
+even without assuming the presence of extreme magnetic fields. Effects of small
+pressure anisotropy on the Hydrogen burning limit in low mass stars are also
+briefly commented upon. It is shown that here the isotropic case can predict a
+theoretical lower bound on the scalar tensor parameter, in addition to a known
+upper bound.",1811.07685v1
+2018-12-23,Indication of nearby source signatures of cosmic rays from energy spectra and anisotropies,"The origin of Galactic cosmic rays (GCRs) remains a mystery after more than
+one century of their discovery. The diffusive propagation of charged particles
+in the turbulent Galactic magnetic field makes us unable to trace back to their
+acceleration sites. Nevertheless, nearby GCR source(s) may leave imprints on
+the locally measured energy spectra and the anisotropies of the arrival
+direction. In this work we propose a simple but natural description of the GCR
+production and propagation, within a two-zone disk-halo diffusion scenario
+together with a nearby source, to understand the up-to-date precise
+measurements of the energy spectra and anisotropies of GCRs. We find that a
+common energy scale of $\sim100$ TeV appears in both energy spectra of protons
+and Helium nuclei measured recently by CREAM and large-scale anisotropies
+detected by various experiments. These results indicate that one or more local
+sources are very likely important contributors to GCRs below $100$ TeV. This
+study provides a probe to identify source(s) of GCRs by means of joint efforts
+of spectral and anisotropy measurements.",1812.09673v2
+2018-12-31,Electric field switching of the uniaxial magnetic anisotropy of an antiferromagnet,"Electric field control of magnetic anisotropy in ferromagnets has been
+intensively pursued in spintronics to achieve efficient memory and computing
+devices with low energy consumption. Compared with ferromagnets,
+antiferromagnets hold huge potential in high-density information storage for
+their ultrafast spin dynamics and vanishingly small stray field. However, the
+switching of magnetic anisotropy of antiferromagnets via electric field remains
+elusive. Here we use ferroelastic strain from piezoelectric materials to switch
+the uniaxial magnetic anisotropy and the N\'eel order reversibly in
+antiferromagnetic Mn2Au films with an electric field of only a few kV/cm at
+room temperature. Owing to the uniaxial magnetic anisotropy, a ratchet-like
+switching behavior driven by the N\'eel spin-orbit torque is observed in the
+Mn2Au, which can be reversed by electric fields.",1812.11868v1
+2019-02-26,Tensor-valued diffusion MRI in under 3 minutes: An initial survey of microscopic anisotropy and tissue heterogeneity in intracranial tumors,"Purpose: To evaluate the feasibility of a 3-minute b-tensor encoding protocol
+for diffusion MRI-based assessment of the microscopic anisotropy and tissue
+heterogeneity in a wide range of intracranial tumors. Methods: B-tensor
+encoding was performed in 42 patients with intracranial tumors (gliomas,
+meningiomas, adenomas, metastases). Microscopic anisotropy and tissue
+heterogeneity were evaluated by estimating the anisotropic kurtosis ($MK_A$)
+and isotropic kurtosis ($MK_I$), respectively. An extensive imaging protocol
+was compared with a faster 3-minute protocol. Results: The fast imaging
+protocol yielded parameters with characteristics in terms of bias and precision
+similar to the full protocol. Glioblastomas had lower microscopic anisotropy
+than meningiomas $(MK_A = 0.29 \pm 0.06$ versus $0.45\pm0.08, p = 0.003)$.
+Metastases had higher tissue heterogeneity $(MK_I = 0.57\pm0.07)$ than both the
+glioblastomas $(0.44\pm0.06, p < 0.001)$ and meningiomas $(0.46\pm0.06, p =
+0.03)$. Conclusion: Evaluation of the microscopic anisotropy and tissue
+heterogeneity in intracranial tumor patients is feasible in clinically relevant
+times frames.",1902.09986v1
+2019-03-05,Anisotropy-based robust performance criteria for statistically uncertain linear continuous time invariant stochastic systems,"This paper is concerned with robust performance criteria for linear
+continuous time invariant stochastic systems driven by statistically uncertain
+random processes. The uncertainty is understood as the deviation of imprecisely
+known probability distributions of the input disturbance from those of the
+standard Wiener process. Using a one-parameter family of conformal maps of the
+unit disk in the complex plane onto the right half-plane for discrete and
+continuous time transfer functions, the deviation from the nominal Gaussian
+white-noise model is quantified by the mean anisotropy for the input of a
+discrete-time counterpart of the original system. The parameter of this
+conformal correspondence specifies the time scale for filtered versions of the
+input and output of the system, in terms of which the worst-case root mean
+square gain is formulated subject to an upper constraint on the mean
+anisotropy. The resulting two-parameter counterpart of the
+anisotropy-constrained norm of the system for the continuous time case is
+amenable to state-space computation using the methods of the anisotropy-based
+theory of stochastic robust filtering and control, originated by the author in
+the mid 1990s.",1903.01692v1
+2019-04-02,On temperature-dependent anisotropies of upper critical field and London penetration depth,"We show on a few examples of one-band materials with spheroidal Fermi
+surfaces and anisotropic order parameters that anisotropies $\gamma_H$ of the
+upper critical field and $\gamma_\lambda$ of the London penetration depth
+depend on temperature, the feature commonly attributed to multi-band
+superconductors. The parameters $\gamma_H$ and $\gamma_\lambda$ may have
+opposite temperature dependencies or may change in the same direction depending
+on Fermi surface shape and on character of the gap nodes. For two-band systems,
+the behavior of anisotropies is affected by the ratios of bands densities of
+states, Fermi velocities, anisotropies, and order parameters. We investigate in
+detail the conditions determining the directions of temperature dependences of
+the two anisotropy factors.",1904.01161v2
+2019-04-11,Triangular array of iron-oxide nanoparticles: A simulation study of intra- and inter-particle magnetism,"A study of spherical maghemite nanoparticles on a two dimensional triangular
+array was carried out using a stochastic Landau-Lifshitz-Gilbert (sLLG)
+approach. The simulation method was first validated with a triangular array of
+simple dipoles, where results show the expected phase transition to a
+ferromagnetic state at a finite temperature. The ground state exhibited a
+continuous degeneracy that was lifted by an order-from-disorder mechanism at
+infinitesimal temperatures with the appearance of a six-fold planar anisotropy.
+The nanoparticle array consisted of 7.5 nm diameter maghemite spheres with
+bulk-like superexchange interactions between Fe-ions in the core, and weaker
+exchange between surface Fe-ions and a radial anisotropy. The triangular
+nanoparticle array ordered at the same reduced temperature as the simple dipole
+array, but exhibited different behaviour at low temperatures due to the surface
+anisotropy. We find that the vacancies on the octahedral sites in the
+nanoparticles combine with the surface anisotropy to produce an effective
+random temperature-dependent anisotropy for each particle. This leads to a
+reduction in the net magnetization of the nanoparticle array at zero
+temperature compared to the simple dipole array.",1904.05515v1
+2019-04-16,Stochastic gravitational wave background anisotropies in the mHz band: astrophysical dependencies,"We show that the anisotropies of the astrophysical stochastic gravitational
+wave background in the mHz band have a strong dependence on the modelling of
+galactic and sub-galactic physics. We explore a wide range of self-consistent
+astrophysical models for stellar evolution and for the distribution of orbital
+parameters, all calibrated such that they predict the same number of resolved
+mergers to fit the number of detections during LIGO/Virgo O1+O2 observations
+runs. We show that different physical choices for the process of black hole
+collapse and cut-off in the black hole mass distribution give fractional
+differences in the angular power spectrum of anisotropies up to 50\% on all
+angular scales. We also point out that the astrophysical information which can
+be extracted from anisotropies is complementary to the isotropic background and
+individual mergers. These results underline the interest in the anisotropies of
+the stochastic gravitational wave background as a new and potentially rich
+field of research, at the cross-road between astrophysics and cosmology.",1904.07757v2
+2019-04-22,Strain-Induced Reversible Manipulation of Orbital Magnetic Moments in Ni/Cu Multilayers on Ferroelectric BaTiO3,"Controlling magnetic anisotropy by orbital magnetic moments related to
+interfacial strains has considerable potential for the development of future
+devices using spins and orbitals. For the fundamental physics, the relationship
+between strain and orbital magnetic moment is still unknown, because there are
+few tools to probe changes of orbital magnetic moment. In this study, we
+developed an electric-field- (E)-induced X-ray magnetic circular dichroism
+(EXMCD) technique to apply E to a ferroelectric BaTiO3 substrate. We reversibly
+tuned the interfacial lattice constants of Ni/Cu multilayers on BaTiO3 using
+this technique. As the domain structures in BaTiO3 are modulated by E, EXMCD
+measurements reveal that the changes in the magnetic anisotropy of Ni/Cu films
+are induced through the modulation of orbital magnetic moments in Ni with
+magneto-elastic contributions. The strained Ni layer that induces the
+perpendicular magnetic anisotropy without E is released at E = 8 kV/cm, and
+in-plane magnetization also occurs. We observed that EXMCD measurements
+clarified the origin of the reversible changes in perpendicular magnetic
+anisotropy and established the relationship between macroscopic inverse
+magnetostriction effects and microscopic orbital moment anisotropy.",1904.09719v1
+2019-06-01,Influence of initial-state momentum anisotropy on the final-state collectivity in small collision systems,"A multi-phase transport model is used to understand the origin of long-range
+collective azimuthal correlations in small-system collisions. To disentangle
+between collectivity associated with initial-state intrinsic momentum
+anisotropy and the collectivity arising as a final-state response to the
+collision geometry, we studied the development of collectivity in 5.02 TeV
+$p$+Pb collisions with both initial-state and final-state effects included. We
+find that the initial momentum anisotropy may not be fully isotropized through
+parton interactions, and the final-state partonic collectivity in general are
+correlated with both the initial momentum anisotropy and the shape of the
+collision geometry. The initial momentum anisotropy also influences the event
+by event fluctuation of collective flow. Therefore the mere evidence of
+geometry response of the collective flow can not rule out the presence of large
+contributions from the initial state.",1906.01422v1
+2019-09-05,The role of faceting and elongation on the magnetic anisotropy of magnetite Fe3O4 nanocrystals,"Fe3O4 nanoparticles are one of the most promising candidates for biomedical
+applications such as magnetic hyperthermia and theranostics due to their
+bio-compatibility, structural stability and good magnetic properties. However,
+much is unknown about the nanoscale origins of the observed magnetic properties
+of particles due to the dominance of surface and finite size effects. Here we
+have developed an atomistic spin model of elongated magnetite nanocrystals to
+specifically address the role of faceting and elongation on the magnetic shape
+anisotropy. We find that for faceted particles simple analytical formulae
+overestimate the magnetic shape anisotropy and that the underlying cubic
+anisotropy makes a significant contribution to the energy barrier for
+moderately elongated particles. Our results enable a better estimation of the
+effective magnetic anisotropy of highly crystalline magnetite nanoparticles and
+is a step towards quantitative prediction of the heating effects of magnetic
+nanoparticles.",1909.02470v1
+2019-09-19,Large- and Medium-Scale Anisotropies in the Arrival Directions of Cosmic Rays observed with KASCADE-Grande,"We search for anisotropies in the arrival directions of cosmic rays observed
+by the KASCADE-Grande air shower experiment. The analysis is based on public
+data of about 23.7 million events with reconstructed primary energies above 1
+PeV. We apply a novel maximum-likelihood reconstruction method for the cosmic
+ray anisotropy, that compensates for spurious anisotropies induced by local
+detector effects. We find no evidence for a large-scale dipole anisotropy in
+the data, consistent with official results based on the conventional East-West
+derivative method. On the other hand, a subset of cosmic rays with median
+energy of 33 PeV shows strong evidence for a medium-scale feature with an
+angular diameter of 40 degrees. After accounting for the look-elsewhere effect,
+the post-trial significance of this medium-scale feature is at the level of
+4$\sigma$.",1909.09222v2
+2019-10-03,Photoemission Spectrum of Ca2RuO4: Spin Polaron Physics in an S=1 Antiferromagnet with Anisotropies,"We derive an S=1 spin polaron model which describes the motion of a single
+hole introduced into the S=1 spin antiferromagnetic ground state of Ca2RuO4. We
+solve the model using the self-consistent Born approximation and show that its
+hole spectral function qualitatively agrees with the experimentally observed
+high-binding energy part of the Ca2RuO4 photoemission spectrum. We explain the
+observed peculiarities of the photoemission spectrum by linking them to two
+anisotropies present in the employed model---the spin anisotropy and the
+hopping anisotropy. We verify that these anisotropies, and not the possible
+differences between the ruthenate (S=1) and the cuprate (S=1/2) spin polaron
+models, are responsible for the strong qualitative differences between the
+photoemission spectrum of Ca2RuO4 and of the undoped cuprates.",1910.01605v1
+2019-10-15,Constraining the anisotropy of the Universe via Pantheon supernovae sample,"We test the possible dipole anisotropy of a Finslerian cosmological model and
+other three dipole-modulated cosmological models, i.e., the dipole-modulated
+$\rm{\Lambda}$CDM, $w$CDM and Chevallier--Polarski--Linder (CPL) model by using
+the recently released Pantheon sample of SNe Ia. The Markov chain Monte Carlo
+(MCMC) method is used to explore the whole parameter space. We find that the
+dipole anisotropy is very weak in all cosmological models used. Although the
+dipole amplitudes of four cosmological models are consistent with zero within
+$1\sigma$ uncertainty, the dipole directions are close to the axial direction
+to the plane of SDSS subsample among Pantheon. It may imply that the weak
+dipole anisotropy in the Pantheon sample originates from the inhomogeneous
+distribution of the SDSS subsample. More homogeneous distribution of SNe Ia is
+necessary to constrain the cosmic anisotropy.",1910.06883v1
+2019-12-10,Effects of substrate anisotropy and edge diffusion on submonolayer growth during molecular beam epitaxy: A Kinetic Monte Carlo study,"We have performed Kinetic Monte Carlo simulation work to study the effect of
+diffusion anisotropy, bonding anisotropy and edge diffusion on island formation
+at different temperatures during the sub-monolayer film growth in Molecular
+Beam Epitaxy. We use simple cubic solid on solid model and event based Bortz,
+Kalos and Labowitch (BKL) algorithm on the Kinetic Monte Carlo method to
+simulate the physical phenomena. We have found that the island morphology and
+growth exponent are found to be influenced by substrate anisotropy as well as
+edge diffusion, however they do not play a significant role in island
+elongation. The growth exponent and island size distribution are observed to be
+influenced by substrate anisotropy but are negligibly influenced by edge
+diffusion. We have found fractal islands when edge diffusion is excluded and
+compact islands when edge diffusion is included.",1912.05918v1
+2020-01-10,Unidirectional tilt of domain walls in equilibrium in biaxial stripes with Dzyaloshinskii-Moriya interaction,"The orientation of a chiral magnetic domain wall in a racetrack determines
+its dynamical properties. In equilibrium, magnetic domain walls are expected to
+be oriented perpendicular to the stripe axis. We demonstrate the appearance of
+a unidirectional domain wall tilt in out-of-plane magnetized stripes with
+biaxial anisotropy and Dzyaloshinskii--Moriya interaction (DMI). The tilt is a
+result of the interplay between the in-plane easy-axis anisotropy and DMI. We
+show that the additional anisotropy and DMI prefer different domain wall
+structure: anisotropy links the magnetization azimuthal angle inside the domain
+wall with the anisotropy direction in contrast to DMI, which prefers the
+magnetization perpendicular to the domain wall plane. Their balance with the
+energy gain due to domain wall extension defines the equilibrium magnetization
+the domain wall tilting. We demonstrate that the Walker field and the
+corresponding Walker velocity of the domain wall can be enhanced in the system
+supporting tilted walls.",2001.03408v1
+2020-02-10,"Phase diagram of the mixed-spin (1,3/2) Ising ferrimagnetic system with two different anisotropies","In this work, we have performed Monte Carlo simulations to study phase
+transitions in a mixed spin-1 and spin-3/2 Ising ferrimagnetic system on the
+square and cubic lattices and with two different single-ion anisotropies. This
+lattice is divided in two interpenetrating sublattices with spins $S^A = 1$
+(states $\pm1$ and 0) on the sublattice $A$ and $S^B = 3/2$ (states $\pm 3/2$,
+$\pm 1/2$) on the sublattice $B$. We have used single-ion anisotropies $D_{A}$
+and $D_{B}$ acting on the sites of the sublattice $A$ and $B$, receptively. We
+have determined the phase diagrams of the model in the temperature $T$ versus
+the single-ion anisotropies strength $D_A$ and $D_B$ plane and shown that the
+system exhibits both second- and first-order phase transitions. We also have
+shown that this system displays compensation points for some values of the
+anisotropies.",2002.08421v1
+2020-02-20,Dynamics of quantum anisotropies in a Taub Universe in the WKB approximation,"We analyze the dynamics of a Taub cosmological model in the presence of a
+massless minimally coupled scalar field and a cosmological constant, in the
+limit when both the Universe volume and the scalar field live in a
+quasi-classical approximation. By other words, we study the dynamics of a
+quantum small anisotropy evolving on a de Sitter background and in the presence
+of a kinetic term of the inflaton field. We demonstrate that the quantum
+anisotropy exponentially decays during the Universe expansion, approaching a
+finite and small value. This result suggests that the quantum isotropization of
+the Universe during a de Sitter phase is much weaker than the corresponding
+classical evolution, favouring the survival of certain degree of anisotropy to
+the de Sitter phase. Finally we analyze the case when also the scalar field is
+considered as quantum variable, by showing how its variance naturally spreads
+because of no potential term significantly affects its dynamics. This behaviour
+results to be different from the anisotropy which is subjected to the potential
+coming out from the spatial curvature.",2002.08687v3
+2020-02-28,Experimental determination of the orientation of tilted magnetic anisotropy by measuring Hall voltage,"The orientation of the tilted magnetic anisotropy has crucial importance in
+many spintronic devices. However, it is very challenging to determine it
+especially in very small structures produced by lithography. Here, we propose a
+new experimental method to directly and accurately measure both the polar and
+azimuthal angles of a tilted magnetic anisotropy. By using the proposed
+experimental method, we have successfully determined the out-of-plane and
+in-plane angles of the tilted magnetic anisotropy in a micro-structured
+multilayer thin film. The orientation of the tilted magnetic anisotropy in the
+sample has also been confirmed by the theoretical simulations proving the
+accuracy of the method.",2003.00038v1
+2020-03-27,Effect of random anisotropy in stabilization of topological chiral textures,"Ever increasing demand of skyrmion manipulation in nanodevices has brought up
+interesting research to 8 understand the stabilization of these topologically
+protected chiral structures. To understand the actual shape 9 and size of
+skyrmion observed experimentally, we have performed micromagnetic simulations
+to investigate 10 skyrmion stabilization in presence of random anisotropy in
+magnetic thin film system. Previous experimental 11 reports of skyrmion imaging
+in thin films depicts that the skyrmion shape is not perfectly circular. Here
+we 12 show via simulations that the shape of a skyrmion can get distorted due
+to the presence of different local 13 anisotropy energy. The values of uniaxial
+anisotropy constant (Ku) and random aniostropy constant (Kr) 14 are varied to
+understand the change in shape and size of a skyrmion and an antiskyrmion
+stabilized in a 15 square magnetic nanoelement. The skyrmion shape gets
+distorted and the size gets constant for high random 16 anisotropy energy in
+the system.",2003.12481v1
+2020-04-11,Studying the local magnetic field and anisotropy of magnetic turbulence by synchrotron polarization derivative,"Due to the inevitable accumulation of the observed information in the
+direction of the line of sight, it is difficult to measure the local magnetic
+field of MHD turbulence. However, the correct understanding of the local
+magnetic field is a prerequisite for reconstructing the Galactic 3D magnetic
+field. We study how to reveal the local magnetic field direction and the eddy
+anisotropy on the basis of the statistics of synchrotron polarization
+derivative with respect to the squared wavelength $dP/d\lambda^2$. In the low
+frequency and strong Faraday rotation regime, we implement numerical
+simulations in the combination of multiple statistic techniques, such as
+structure function, quadrupole ratio modulus, spectral correlation function,
+correlation function anisotropy and spatial gradient techniques. We find that
+(1) statistic analysis of $dP/d\lambda^2$ indeed reveals the anisotropy of
+underlying MHD turbulence, the degree of which increases with the increase of
+the radiation frequency; (2) the synergy of both correlation function
+anisotropy and gradient calculation of $dP/d\lambda^2$ enables the measurement
+of the local magnetic field direction.",2004.05270v1
+2020-06-22,Searching for anisotropy in the distribution of binary black hole mergers,"The standard model of cosmology is underpinned by the assumption of the
+statistical isotropy of the Universe. Observations of the cosmic microwave
+background, galaxy distributions, and supernovae, among other media, support
+the assumption of isotropy at scales $\gtrsim 100$\,Mpc. The recent detections
+of gravitational waves from merging stellar-mass binary black holes provide a
+new probe of anisotropy; complementary and independent of all other probes of
+the matter distribution in the Universe. We present an analysis using a
+spherical harmonic model to determine the level of anisotropy in the first
+LIGO/Virgo transient catalog. We find that the ten binary black hole mergers
+within the first transient catalog are consistent with an isotropic
+distribution. We carry out a study of simulated events to assess the prospects
+for future probes of anisotropy. Within a single year of operation,
+third-generation gravitational-wave observatories will probe anisotropies with
+an angular scale of $\sim36^\circ$ at the level of $\lesssim0.1\%$.",2006.11957v2
+2020-07-19,Isostructural spin-density-wave and superconducting gap anisotropies in iron-arsenide superconductors,"When passing through a phase transition, electronic system saves energy by
+opening energy gaps at the Fermi level. Delineating the energy gap anisotropy
+provides insights into the origin of the interactions that drive the phase
+transition. Here, we report the angle-resolved photoemission spectroscopy
+(ARPES) study on the detailed gap anisotropies in both the tetragonal magnetic
+and superconducting phases in Sr$_{1-x}$Na$_x$Fe$_2$As$_2$. First, we found
+that the spin-density-wave (SDW) gap is strongly anisotropic in the tetragonal
+magnetic phase. The gap magnitude correlates with the orbital character of
+Fermi surface closely. Second, we found that the SDW gap anisotropy is
+isostructural to the superconducting gap anisotropy regarding to the angular
+dependence, gap minima locations, and relative gap magnitudes. Our results
+indicate that the superconducting pairing interaction and magnetic interaction
+share the same origin. The intra-orbital scattering plays an important role in
+constructing these interactions resulting in the orbital-selective magnetism
+and superconductivity in iron-based superconductors.",2007.09572v1
+2020-07-27,Effect of momentum anisotropy on quark matter in the quark-meson model,"We investigate the chiral phase structure of quark matter with spheroidal
+momentum-space anisotropy specified by one anisotropy parameter $\xi$ in the
+2+1 flavor quark-meson model. We find that the chiral phase diagram and the
+location of the critical endpoint (CEP) are affected significantly by the value
+of $\xi$. With the increase of $\xi$, the CEP is shifted to smaller
+temperatures and larger quark chemical potentials. And the temperature of the
+CEP is more sensitive to the anisotropy parameter than the corresponding quark
+chemical potential, which is opposite to the study for finite system volume
+effect. Furthermore, the effects of momentum anisotropy on the thermodynamic
+properties and scalar (pseudoscalar) meson masses are also studied at vanishing
+quark chemical potential. The numerical results show that an increase of $\xi$
+can hinder the restoration of chiral symmetry. We also find that shear
+viscosity and electrical conductivity decrease as $\xi$ grows. However, bulk
+viscosity exhibits a significant non-trivial behavior with $\xi$ in the entire
+temperature domain of interest.",2007.13580v3
+2020-08-20,Two-dimensional ferromagnetic semiconductor VBr3 with tunable anisotropy,"Two-dimensional (2D) ferromagnets (FMs) have attracted widespread attention
+due to their prospects in spintronic applications. Here we explore the
+electronic structure and magnetic properties of the bulk and monolayer of
+VBr$_{3}$ in the honeycomb lattice, using first-principles calculations,
+crystal field level analyses, and Monte Carlo simulations. Our results show
+that VBr$_{3}$ bulk has the $e'_{g}$$^2$ ($S$=1) ground state and possesses a
+small orbital moment and weak in-plane magnetic anisotropy. Those results well
+explain the recent experiments. More interestingly, we find that a tensile
+strain on the semiconducting VBr$_{3}$ monolayer tunes the ground state into
+$a_{1g}$$^1$$e'_{g}$$^1$ and thus produces a large orbital moment and a strong
+out-of-plane anisotropy. Then, the significantly enhanced FM superexchange and
+single ion anisotropy (SIA) would raise $T_{\rm C}$ from 20 K for the bare
+VBr$_{3}$ monolayer to 100-115 K under a 2.5$\%$-5$\%$ strain. Therefore,
+VBr$_{3}$ would be a promising 2D FM semiconductor with a tunable anisotropy.",2008.09232v2
+2020-09-28,Bi-directional streaming of particles accelerated at the STEREO-A shock on 9th March 2008,"We present an interpretation of anisotropy and intensity of supra-thermal
+ions near a fast quasi-perpendicular reverse shock measured by Solar
+Terrestrial Relations Observatory Ahead (ST-A) on 2008 March 9th. The measured
+intensity profiles of the supra-thermal particles exhibit an enhancement, or
+""spike"", at the time of the shock arrival and pitch-angle anisotropies before
+the shock arrival are bi-modal, jointly suggesting trapping of
+near-scatter-free ions along magnetic field lines that intersect the shock at
+two locations. We run test-particle simulations with pre-existing upstream
+magnetostatic fluctuations advected across the shock. The measured bi-modal
+upstream anisotropy, the nearly field-aligned anisotropies up to ~15 minutes
+upstream of the shock, as well as the ""pancake-like"" anisotropies up to ~10
+minutes downstream of the shock are well reproduced by the simulations. These
+results, in agreement with earlier works, suggest a dominant role of the
+large-scale structure (100s of supra-thermal proton gyroradii) of the magnetic
+field in forging the early-on particle acceleration at shocks.",2009.13662v1
+2020-10-01,"Anisotropic spin distribution and perpendicular magnetic anisotropy in the layered ferromagnetic semiconductor (Ba,K)(Zn,Mn)$_{2}$As$_{2}$","Perpendicular magnetic anisotropy of the new ferromagnetic semiconductor
+(Ba,K)(Zn,Mn)$_{2}$As$_{2}$ is studied by angle-dependent x-ray magnetic
+circular dichroism measurements. The large magnetic anisotropy with the
+anisotropy field of 0.85 T is deduced by fitting the Stoner-Wohlfarth model to
+the magnetic-field-angle dependence of the projected magnetic moment.
+Transverse XMCD spectra highlights the anisotropic distribution of Mn 3$d$
+electrons, where the $d_{xz}$ and $d_{yz}$ orbitals are less populated than the
+$d_{xy}$ state because of the $D_{2d}$ splitting arising from the elongated
+MnAs$_{4}$ tetrahedra. It is suggested that the magnetic anisotropy originates
+from the degeneracy lifting of $p$-$d_{xz}$, $d_{yz}$ hybridized states at the
+Fermi level and resulting energy gain due to spin-orbit coupling when spins are
+aligned along the $z$ direction.",2010.00158v1
+2020-10-08,Anisotropy and multifractal analysis of turbulent velocity and temperature in the roughness sublayer of a forested canopy,"Anisotropy and multifractality in velocity and temperature time series
+sampled at multiple heights in the roughness sublayer (RSL) over a boreal
+mixed-coniferous forest are reported. In particular, a turbulent-stress
+invariant analysis along with a scalewise version of it are conducted to
+elucidate the nature of relaxation of large-scale anisotropy to quasi-isotropic
+states at small scales. As the return to isotropy is linked to nonlinear
+interactions and correlations between different fluctuating velocity components
+across scales, we study the velocity and temperature time series by using
+multifractal detrended fluctuation analysis and multiscale multifractal
+analysis to assess the effects of thermal stratification and surface roughness
+on turbulence in the RSL. The findings are compared so as to quantify the
+anisotropy and multifractality ubiquitous to RSL turbulent flow. As we go up in
+the RSL, (a) the length scale at which return to isotropy commences increases
+because of the weakening of the surface effects and (b) the largest scales
+become increasingly anisotropic. The anisotropy in multifractal exponents for
+the velocity fluctuations is diminished when we use the
+extended-self-similarity procedure to extract the multifractal-exponent ratios.",2010.04194v1
+2020-11-11,Field and anisotropy driven transformations of spin spirals in cubic skyrmion hosts,"We discuss distinctive features of spiral states in bulk chiral magnets such
+as MnSi and Cu$_2$OSeO$_3$ that stem from the effect of the cubic
+magneto-crystalline anisotropy. First of all, at both the helical-to-conical
+and the conical-to-ferromagnetic transitions, taking place at H$_{c1}$ and
+H$_{c2}$, respectively, the cubic anisotropy leads to reversible or
+irreversible jump-like reorientations of the spiral wavevectors. The subtle
+interplay between the easy and hard anisotropy axes gives rise to a phase
+transition between elliptically distorted conical states almost without any
+detectable change in the period. We show that the competition between on-site
+cubic and exchange anisotropy terms can also lead to oblique spiral states. Our
+work gives clear directions for further experimental studies to reveal
+theoretically predicted spiral states in cubic helimagnets beyond the
+aforementioned well-established states thus, can help to understand the
+magnetic phase diagram of these archetypal skyrmion hosts. In addition, we show
+that properties of isolated skyrmions such as inter-skyrmion attraction,
+orientation and/or nucleation are also rooted in the properties of host spirals
+states, in which skyrmions are stabilized.",2011.05501v1
+2020-11-13,Magnetic anisotropy of individual maghemite mesocrystals,"Interest in creating magnetic metamaterials has led to methods for growing
+superstructures of magnetic nanoparticles. Mesoscopic crystals of maghemite
+($\gamma\text{-Fe}_2\text{O}_3$) nanoparticles can be arranged into highly
+ordered body-centered tetragonal lattices of up to a few micrometers. Although
+measurements on disordered ensembles have been carried out, determining the
+magnetic properties of individual mesoscopic crystals is challenging due to
+their small total magnetic moment. Here, we overcome these challenges by
+utilizing sensitive dynamic cantilever magnetometry to study individual
+micrometer-sized $\gamma\text{-Fe}_2\text{O}_3$ mesocrystals. These
+measurements reveal an unambiguous cubic anisotropy, resulting from the
+crystalline anisotropy of the constituent maghemite nanoparticles and their
+alignment within the mesoscopic lattice. The signatures of anisotropy and its
+orgins come to light because we combine the self-assembly of highly ordered
+mesocrystals with the ability to resolve their individual magnetism. This
+combination is promising for future studies of the magnetic anisotropy of other
+nanoparticles, which are too small to investigate individually.",2011.06885v1
+2020-11-18,Suppression of transport anisotropy at the Anderson localization transition in three-dimensional anisotropic media,"We study the transport of classical waves through three-dimensional (3D)
+anisotropic media close to the Anderson localization transition. Time-,
+frequency-, and position-resolved ultrasonic measurements are performed on
+anisotropic slab-shaped mesoglass samples to probe the dynamics and the
+anisotropy of the multiple scattering halo, and hence to investigate the
+influence of disorder on the nature of wave transport and its anisotropy. These
+experiments allow us to address conflicting theoretical predictions that have
+been made about whether or not the transport anisotropy is affected by the
+interference effects that lead to Anderson localization. We find that the
+transport anisotropy is significantly reduced as the mobility edge is
+approached---a behavior similar to the one predicted recently for matter waves
+in infinite anisotropic 3D media.",2011.09560v1
+2021-01-07,Mechanisms behind large Gilbert damping anisotropies,"A method with which to calculate the Gilbert damping parameter from a
+real-space electronic structure method is reported here. The anisotropy of the
+Gilbert damping with respect to the magnetic moment direction and local
+chemical environment is calculated for bulk and surfaces of Fe$_{50}$Co$_{50}$
+alloys from first principles electronic structure in a real space formulation.
+The size of the damping anisotropy for Fe$_{50}$Co$_{50}$ alloys is
+demonstrated to be significant. Depending on details of the simulations, it
+reaches a maximum-minimum damping ratio as high as 200%. Several microscopic
+origins of the strongly enhanced Gilbert damping anisotropy have been examined,
+where in particular interface/surface effects stand out, as do local
+distortions of the crystal structure. Although theory does not reproduce the
+experimentally reported high ratio of 400% [Phys. Rev. Lett. 122, 117203
+(2019)], it nevertheless identifies microscopic mechanisms that can lead to
+huge damping anisotropies.",2101.02794v2
+2021-01-25,Correlation between initial spatial anisotropy and final momentum anisotropies in relativistic heavy ion collisions,"The particle momentum anisotropy ($v_n$) produced in relativistic nuclear
+collisions is considered to be a response of the initial geometry or the
+spatial anisotropy $\epsilon_n$ of the system formed in these collisions. The
+linear correlation between $\epsilon_n$ and $v_n$ quantifies the efficiency at
+which the initial spatial eccentricity is converted to final momentum
+anisotropy in heavy ion collisions. We study the transverse momentum, collision
+centrality, and beam energy dependence of this correlation for different
+charged particles using a hydrodynamical model framework. The ($\epsilon_n
+-v_n$) correlation is found to be stronger for central collisions and also for
+n=2 compared to that for n=3 as expected. However, the transverse momentum
+($p_T$) dependent correlation coefficient shows interesting features which
+strongly depends on the mass as well as $p_T$ of the emitted particle. The
+correlation strength is found to be larger for lighter particles in the lower
+$p_T$ region. We see that the relative fluctuation in anisotropic flow depends
+strongly in the value of $\eta/s$ specially in the region $p_T <1$ GeV unlike
+the correlation coefficient which does not show significant dependence on
+$\eta/s$.",2101.09998v1
+2021-03-10,Anisotropy with respect to the applied magnetic field of spin qubit decoherence times,"Electron spin qubits are a promising platform for quantum computation.
+Environmental noise impedes coherent operations by limiting the qubit
+relaxation ($T_1$) and dephasing ($T_{\phi}$) times. There are multiple sources
+of such noise, which makes it important to devise experimental techniques that
+can detect the spatial locations of these sources and determine the type of
+source. In this paper, we propose that anisotropy in $T_1$ and $T_{\phi}$ with
+respect to the direction of the applied magnetic field can reveal much about
+these aspects of the noise. We investigate the anisotropy patterns of charge
+noise, evanescent-wave Johnson noise, and hyperfine noise in hypothetical
+devices. It is necessary to have a rather well-characterized sample to get the
+maximum benefit from this technique. The general anisotropy patterns are
+elucidated. We calculate the expected anisotropy for a particular model of a
+Si/SiGe quantum dot device.",2103.05865v3
+2021-03-14,Fusion yield of plasma with velocity-space anisotropy at constant energy,"Velocity-space anisotropy can significantly modify fusion reactivity. The
+nature and magnitude of this modification depends on the plasma temperature, as
+well as the details of how the anisotropy is introduced. For plasmas that are
+sufficiently cold compared to the peak of the fusion cross-section, anisotropic
+distributions tend to have higher yields than isotropic distributions with the
+same thermal energy. At higher temperatures, it is instead isotropic
+distributions that have the highest yields. However, the details of this
+behavior depend on exactly how the distribution differs from an isotropic
+Maxwellian. This paper describes the effects of anisotropy on fusion yield for
+the class of anisotropic distribution functions with the same energy
+distribution as a 3D isotropic Maxwellian, and compares those results with the
+yields from bi-Maxwellian distributions. In many cases, especially for plasmas
+somewhat below reactor-regime temperatures, the effects of anisotropy can be
+substantial.",2103.07834v2
+2021-03-16,Complete mapping of magnetic anisotropy for prototype Ising van der Waals FePS$_3$,"Several Ising-type magnetic van der Waals (vdW) materials exhibit stable
+magnetic ground states. Despite these clear experimental demonstrations, a
+complete theoretical and microscopic understanding of their magnetic anisotropy
+is still lacking. In particular, the validity limit of identifying their
+one-dimensional (1-D) Ising nature has remained uninvestigated in a
+quantitative way. Here we performed the complete mapping of magnetic anisotropy
+for a prototypical Ising vdW magnet FePS$_3$ for the first time. Combining
+torque magnetometry measurements with their magnetostatic model analysis and
+the relativistic density functional total energy calculations, we successfully
+constructed the three-dimensional (3-D) mappings of the magnetic anisotropy in
+terms of magnetic torque and energy. The results not only quantitatively
+confirm that the easy axis is perpendicular to the $ab$ plane, but also reveal
+the anisotropies within the $ab$, $ac$, and $bc$ planes. Our approach can be
+applied to the detailed quantitative study of magnetism in vdW materials.",2103.09029v1
+2021-03-29,Controlling anisotropy in 2D microscopic models of growth,"The quantitative knowledge of interface anisotropy in lattice models is a
+major issue, both for the parametrization of continuum interface models, and
+for the analysis of experimental observations. In this paper, we focus on the
+anisotropy of line tension and stiffness, which plays a major role both in
+equilibrium shapes and fluctuations, and in the selection of nonequilibrium
+growth patterns. We consider a 2D Ising Hamiltonian on a square lattice with
+first and second-nearest-neighbor interactions. The surface stiffness and line
+tension are calculated by means of a broken-bond model for arbitrary
+orientations. The analysis of the interface energy allows us to determine the
+conditions under which stiffness anisotropy is minimal. These results are
+supported by a quantitative comparison with kinetic Monte Carlo simulations,
+based on the coupling of a field of mobile atoms to a condensed phase.
+Furthermore, we introduce a generic smoothing parameter which allows one to
+mimic the finite resolution of experimental microscopy techniques. Our results
+provide a method to fine-tune the interface energy in models of nanoscale
+non-equilibrium processes, where anisotropy and fluctuations combine and give
+rise to non-trivial morphologies.",2103.15535v2
+2021-04-15,Geminga SNR: Possible candidate of local cosmic-ray factory,"The precise measurements of energy spectra and anisotropy could help us
+uncover the local cosmic-ray accelerators. Our recent works have shown that
+spectral hardening above $200$ GeV in the energy spectra and transition of
+large-scale anisotropy at $\sim 100$ TeV are of local source origin. Less than
+$100$ TeV, both spectral hardening and anisotropy explicitly indicate the
+dominant contribution from nearby sources. In this work, we further investigate
+the parameter space of sources allowed by the observational energy spectra and
+anisotropy amplitude. To obtain the best-fit source parameters, a numerical
+package to compute the parameter posterior distributions based on Bayesian
+inference, which is applied to perform an elaborate scan of parameter space. We
+find that by combining the energy spectra and anisotropy data, the permissible
+range of location and age of local source is considerably reduced. When
+comparing with the current local SNR catalog, only Geminga SNR could be the
+proper candidate of the local cosmic-ray source.",2104.07321v1
+2021-04-16,CMB anisotropies generated by cosmic string loops,"We investigate the contribution of cosmic string loops to the Cosmic
+Microwave Background (CMB) anisotropies. This is done by extending the
+Unconnected Segment Model (USM) to include the contribution of the cosmic
+string loops created throughout the cosmological evolution of a cosmic string
+network to the stress-energy tensor. We then implement this extended USM in the
+publicly available CMBACT code and obtain the linear CDM power spectrum and the
+CMB angular power spectra generated by cosmic string loops. We find that the
+shape of the angular power spectra generated by loops is, in general, similar
+to that of long strings. However, there is generally an enhancement of the
+anisotropies on small angular scales. Vector modes produced by loops dominate
+over those produced by long strings for large multipole moments $\ell$. The
+contribution of loops to the CMB anisotropies generated by cosmic string
+networks may reach a level of $10\%$ for large loops but decreases as the size
+of loops decreases. This contribution may then be significant and, thus, this
+extension provides a more accurate prediction of the CMB anisotropies generated
+by cosmic string networks.",2104.08375v2
+2021-05-30,Anisotropy in interface stress at the BCC-iron solid-melt interface: molecular dynamics and phase field crystal modelling,"The interface stresses at of the solid-melt interface are, in general,
+anisotropic. The anisotropy in the interfacial stress can be evaluated using
+molecular dynamics (MD) and phase field crystal (PFC) models. In this paper, we
+report our results on the evaluation of the anisotropy in interface stress in a
+BCC solid with its melt. Specifically, we study Fe using both MD and PFC
+models. We show that while both MD and PFC can be used for the evaluation, and
+the PFC and the amplitude equations based on PFC give quantitatively consistent
+results, the MD and PFC results are qualitatively the same but do not match
+quantitatively. We also find that even though the interfacial free energy is
+only weakly anisotropic in BCC interfacial stress anisotropy is strong. This
+strong anisotropy has implications for the equilibrium shapes, growth
+morphologies and other properties at nano-scale in these materials.",2105.14521v1
+2021-07-01,Large-scale anisotropy of Galactic cosmic rays as a probe of local cosmic-ray propagation,"Recent studies have shown that the anisotropy is of great value to decipher
+cosmic rays' origin and propagation. We have built an unified scenario to
+describe the observations of the energy spectra and the large-scale anisotropy
+and called attention to their synchronously evolution with energy. In this
+work, the impact of of the local regular magnetic field (LRMF) and
+corresponding anisotropic diffusion on large-scale anisotropy have been
+investigated. When the perpendicular diffusion coefficient is much smaller than
+the parallel one, the dipole anisotropy points to the LRMF and the
+observational phase below $100$ TeV could be reproduced. Moreover we find that
+the dipole phase above $100$ TeV strongly depends on the evolution of local
+diffusion. But the current measurements at that energy are still scarce. We
+suggest that more precise measurements at that energy could be carried out to
+unveil the local diffusion and further the local turbulence.",2107.00313v4
+2021-07-15,Hierarchical single-ion anisotropies in spin-1 Heisenberg antiferromagnets on the honeycomb lattice,"We examine the thermal properties of the spin-1 Heisenberg antiferromagnet on
+the honeycomb lattice in the presence of an easy-plane single-ion anisotropy as
+well as the effects of an additional weak in-plane easy-axis anisotropy. In
+particular, using large-scale quantum Monte Carlo simulations, we analyze the
+scaling of the correlation length near the thermal phase transition into the
+ordered phase. This allows us to quantify the temperature regime above the
+critical point in which -- in spite of the additional in-plane easy-axis
+anisotropy -- characteristic easy-plane physics, such as near a
+Berezinskii-Kosterlitz-Thouless transition, can still be accessed. Our
+theoretical analysis is motivated by recent neutron scattering studies of the
+spin-1 compound BaNi${}_2$V${}_2$O${}_8$ in particular, and it addresses basic
+quantum spin models for generic spin-1 systems with weak anisotropies, which we
+probe over the full range of experimentally relevant correlation length scales.",2107.07182v2
+2021-07-30,"Effect of an uniaxial single-ion anisotropy on the quantum and thermal entanglement of a mixed spin-(1/2,$S$) Heisenberg dimer","Exact analytical diagonalization is used to study the bipartite entanglement
+of the antiferromagnetic mixed spin-(1/2,$S$) Heisenberg dimer (MSHD) with the
+help of negativity. Under the assumption of uniaxial single-ion anisotropy
+affecting higher spin-$S$ ($S\!>\!1/2$) entities only, the ground-state
+degeneracy $2S$ is partially lifted and the ground state is two-fold degenerate
+with the total magnetization per dimer $\pm(S\!-\!1/2)$. It is shown that the
+largest quantum entanglement is reached for the antiferromagnetic ground state
+of MSHD with arbitrary half-odd-integer spins $S$, regardless of the exchange
+and single-ion anisotropies. Contrary to this, the degree of a quantum
+entanglement in MSHD with an integer spin $S$ for the easy-plane single-ion
+anisotropy, exhibits an increasing tendency with an obvious spin-$S$ driven
+crossing point. It is shown that the increasing spin magnitude is a crucial
+driving mechanism for an enhancement of a threshold temperature above which the
+thermal entanglement vanishes. The easy-plane single-ion anisotropy together
+with an enlargement of the spin-$S$ magnitude is other significant driving
+mechanism for an enhancement of the thermal entanglement in MSHD.",2107.14620v1
+2021-11-08,All-carbon approach to inducing electrical and optical anisotropy in graphene,"Owing to its array of unique properties, graphene is a promising material for
+a wide variety of applications. Being two-dimensional, the properties of
+graphene are also easily tuned via proximity to other materials. In this work,
+we investigate the possibility of inducing electrical and optical anisotropy in
+graphene by interfacing it with other anisotropic carbon systems, including
+nanoporous graphene and arrays of graphene nanoribbons. We find that such
+materials do indeed induce such anisotropy in graphene, while also preserving
+the unique properties offered by graphene's Dirac band structure, namely its
+superior charge transport and long-wavelength optical absorption. The optical
+anisotropy makes such heterostructures interesting for their use in
+applications related to long-wavelength polarimetry, while the electrical
+anisotropy may be valuable for enhancing the performance of graphene
+photothermoelectric detectors.",2111.04571v1
+2022-01-20,Small-angle neutron scattering by spatially inhomogeneous ferromagnets with a nonzero average uniaxial anisotropy,"Micromagnetic small-angle neutron scattering theory is well established for
+analyzing spin-misalignment scattering data of bulk ferromagnets. Here, this
+theory is extended to allow for a global uniaxial magnetic anisotropy (texture)
+of the material, in addition to the already included random zero-average local
+anisotropy. Macroscopic cross-sections and spin-misalignment response functions
+are computed analytically for several practically relevant mutual anisotropy
+and external magnetic field orientations in both parallel and perpendicular
+scattering geometries for field magnitudes both above and below the rotational
+saturation. Some of these expressions are tested on published experimental data
+of magnetic-field-annealed Vitroperm and plastically-deformed Ni, allowing to
+determine the corresponding global uniaxial anisotropy quality factors.",2201.08334v1
+2022-03-07,Detection of Travel Time Anisotropy from Subsurface Horizontal Magnetic Fields,"A time-distance measurement technique is derived to isolate phase travel time
+anisotropy caused by subsurface horizontal magnetic fields, and a method which
+uses the measured anisotropy to estimate the field's orientation is also
+derived. A simulation of acoustic waves propagating in a uniform, inclined
+magnetic field with solar background structure is used to verify the derived
+technique. Then, the procedure is applied to a numerical simulation of a
+sunspot, for which the subsurface state is known, to provide context for the
+results obtained from the study of several sunspots observed by the
+Helioseismic and Magnetic Imager. Significant anisotropies are detected, on the
+order of one minute, and the subsurface field's azimuth is estimated and
+compared with the azimuth of the surface magnetic field. In all cases, the
+subsurface azimuth is found to be well-aligned with that of the surface, and
+the results from the numerical simulation are used to interpret features in the
+detected travel time anisotropy.",2203.03495v1
+2022-03-18,Prediction of novel two-dimensional rare-earth material with room-temperature ferromagnetism and large perpendicular magnetic anisotropy,"Novel 2D ferromagnets with high Curie temperature and large perpendicular
+magnetic anisotropy are especially attractive owing to the future promising
+application in modern spintronics, but meanwhile the 2D ferromagnetic materials
+with high Curie temperature and large perpendicular magnetic anisotropy are
+rarely reported. Based on density functional theory (DFT) calculations, we
+predict a new kind of 2D ferromagnetic materials - GdB2N2, which possesses
+large magnetic moment, high Curie temperature (335 K) and large perpendicular
+magnetic anisotropy (10.38 meV/f.u.). Biaxial strain ranging from -0.5% to 5%
+and different concentrations of charge-carrier doping are applied to reveal the
+influence on the Curie temperature and magnetic anisotropy energy (MAE).
+Besides, magnetic coupling process within GdB2N2 is found to be via a
+Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism. In summary, our work here
+predicts a novel 2D rare-earth material GdB2N2, which not only enriches the
+category of 2D room-temperature ferromagnets, but also proposes a new
+possibility of combining traditional 2D materials and rare-earth materials to
+achieve more intriguing magnetic properties, finally it carves out the path for
+the next-generation spintronic devices and sensors.",2203.10969v1
+2022-03-31,Primordial Stochastic Gravitational Wave Background Anisotropies: in-in Formalization and Applications,"Primordial non-Gaussianities of the scalar(tensor)-tensor-tensor type
+supporting a non-trivial squeezed component are known to induce anisotropies in
+the stochastic gravitational wave background. We derive the explicit form of
+such anisotropies by making use, for the first time in this context, of the
+in-in formalism for cosmological correlation functions. After illustrating the
+general method and using it for the minimal single-field slow-roll case, we
+apply it to multi-field models, providing both a tree-level and a one-loop
+example. First, we make contact with previous results on anisotropies due to
+the presence of an extra spin-2 field during inflation. Secondly, we calculate
+the 1-loop scalar-tensor-tensor three-point function in the context of
+so-called supersolid inflation. The corresponding gravitational wave anisotropy
+is induced atop a gravitational signal that may be sufficiently large for
+detection.",2203.17192v2
+2022-04-20,Collective modes of gluons in an anisotropic thermo-magnetic medium,"We study the collective modes of gluons in an anisotropic thermal medium in
+the presence of a constant background magnetic field using the hard-thermal
+loop (HTL) perturbation theory. The momentum space anisotropy of the medium has
+been incorporated through the generalized $`$Romatschke-Strickland' form of the
+distribution function, whereas, the magnetic modification arising from the
+quark loop contribution has been taken into account in the lowest Landau level
+approximation. We consider two special cases: (i) a spheroidal anisotropy with
+the anisotropy vector orthogonal to the external magnetic field and (ii) an
+ellipsoidal anisotropy with two mutually orthogonal vectors describing
+aniostropies along and orthogonal to the field direction. The general structure
+of the polarization tensor in both cases are equivalent and consists of six
+independent basis tensors. We find that the introduction of momentum anisotropy
+ingrains azimuthal angular dependence in the thermo-magnetic collective modes.
+Our study suggests that the presence of a strong background magnetic field can
+significantly reduce the growth rate of the unstable modes which may have
+important implications in the equilibration of magnetized quark-gluon plasma.",2204.09646v2
+2022-05-09,Primordial Clocks within Stochastic Gravitational Wave Anisotropies,"A first-order phase transition in the early universe can give an observable
+stochastic gravitational background (SGWB), which will necessarily have
+primordial anisotropies across the sky. In multi-field inflationary scenarios,
+these anisotropies may have a significant isocurvature component very different
+from adiabatic fluctuations, providing an alternate discovery channel for high
+energy physics at inflationary scales. Here, we consider classically
+oscillating heavy fields during inflation that can imprint distinctive
+scale-invariance-breaking features in the power spectrum of primordial
+anisotropies. While such features are highly constrained in the cosmic
+microwave background, we show that their amplitude can be observably large in
+isocurvature SGWB, despite both probing a similar period of inflation.
+Measuring SGWB multipoles at the required level, $\ell \sim {\cal O}(10-100)$,
+will be technologically challenging. However, we expect that early detection of
+a strong isotropic SGWB, and the guarantee of anisotropies, would spur
+development of next-generation detectors with sufficient sensitivity, angular
+resolution, and foreground discrimination.",2205.04482v1
+2022-06-07,The Origin of Deformation Induced Topological Anisotropy in Silica Glass,"Oxide glasses with a network structure are omnipresent in daily life. Often,
+they are regarded as isotropic materials; however, structural anisotropy can be
+induced through processing in mechanical fields and leads to unique materials
+properties. Unfortunately, due to the lack of local, atomic-scale analysis
+methods, the microscopic mechanisms leading to anisotropy remained elusive.
+Using novel analysis methods on glasses generated by molecular dynamics
+simulations, this paper provides a microscopic understanding of topological
+anisotropy in silica (SiO$_2$) glass under mechanical loads. The anisotropy
+observed in silica glass originates from a preferred orientation of SiO$_4$
+tetrahedra at both short- and medium-range levels that can be controlled via
+the mode of mechanical loading. The findings elucidate the relation between the
+deformation protocol and the resulting anisotropic structure of the silica
+network (involving both persistent and transient effects), and thus provide
+important insight for the design of oxide glasses with tailored materials
+properties.",2206.03039v2
+2022-06-08,Observational constraints on anisotropies for bouncing alternatives to inflation,"We calculate how primordial anisotropies in the background space-time affect
+the evolution of cosmological perturbations for bouncing alternatives to
+inflation, like ekpyrosis and the matter bounce scenario. We find that the
+leading order effect of anisotropies in the contracting phase of the universe
+is to induce anisotropies in the cosmic microwave background with a very
+concrete form: a scale-invariant quadrupolar angular distribution. Sub-leading
+effects are the generation of higher-order moments in the angular distribution,
+as well as cross-correlations between scalar and tensor modes. We also find
+that observational constraints from the cosmic microwave background on the
+quadrupole moment provide strong bounds on allowed anisotropies for bouncing
+alternatives to inflation that are significantly more constraining than the
+bounds previously obtained using scaling arguments based on the conjectured
+Belinski-Khalatnikov-Lifshitz instability.",2206.04037v3
+2022-07-22,Frustrated ferromagnetic transition in AB-stacked honeycomb bilayer,"In two-dimensional (2D) ferromagnets, anisotropy is essential for the
+magnetic ordering as dictated by the Mermin-Wagner theorem. But when competing
+anisotropies are present, the phase transition becomes nontrivial. Here,
+utilizing highly sensitive susceptometry of scanning superconducting quantum
+interference device microscopy, we probe the spin correlations of ABC-stacked
+CrBr3 under zero magnetic field. We identify a plateau feature in
+susceptibility above the critical temperature (Tc) in thick samples. It
+signifies a crossover regime induced by the competition between easy-plane
+intralayer exchange anisotropy versus uniaxial interlayer anisotropy. The
+evolution of the critical behavior from the bulk to 2D shows that the
+competition between the anisotropies is magnified in the reduced dimension. It
+leads to a strongly frustrated ferromagnetic transition in the bilayer with
+fluctuation on the order of Tc, which is distinct from both the monolayer and
+the bulk. Our observation potentially offers a 2D localized spin system on
+honeycomb lattice to explore magnetic frustration.",2207.10945v1
+2022-08-15,The origin of enhanced interfacial perpendicular magnetic anisotropy in LiF-inserted Fe/MgO interface,"The Fe/MgO interface is an essential ingredient in spintronics as it shows
+giant tunneling magnetoresistance and strong perpendicular magnetic anisotropy
+(PMA). A recent study demonstrated that the insertion of an ultra-thin LiF
+layer between the Fe and MgO layers enhances PMA significantly. In this study,
+we perform x-ray magnetic circular dichroism measurements on Fe/LiF/MgO
+multilayers to reveal the origin of the PMA enhancement. We find that the LiF
+insertion increases the orbital-magnetic-moment anisotropy and thus the
+magnetic anisotropy energy. We attribute the origin of this
+orbital-magnetic-moment-anisotropy enhancement to the stronger electron
+localization and electron-electron correlation or the better interface quality
+with fewer defects.",2208.07007v1
+2022-09-03,Cosmic-Ray Convection-Diffusion Anisotropy,"Under nonuniform convection, the distribution of diffusive particles can
+exhibit dipole and quadrupole anisotropy induced by the fluid inertial and
+shear force, respectively. These convection-related anisotropies, unlike the
+Compton-Getting effect, typically increase with the cosmic-ray (CR) energy, and
+are thus candidate contributors for the CR anisotropy. In consideration of the
+inertial effect, CR observational data can be used to set an upper limit on the
+average acceleration of the local interstellar medium in the equatorial plane
+to be on the order of 100 $ \mu \text{m}/\text{s}^2 $. Using Oort constants,
+the quadrupole anisotropy above 200 TeV may be modeled with the shear effect
+arising from the Galactic differential rotation.",2209.01412v2
+2022-10-16,Magnetic damping anisotropy in the two-dimensional van der Waals material Fe$_3$GeTe$_2$ from first principles,"Magnetization relaxation in the two-dimensional itinerant ferromagnetic van
+der Waals material Fe$_3$GeTe$_2$, below the Curie temperature, is
+fundamentally important for applications to low-dimensional spintronics
+devices. We use first-principles scattering theory to calculate the
+temperature-dependent Gilbert damping for bulk and single-layer Fe$_3$GeTe$_2$.
+The calculated damping frequency of bulk Fe$_3$GeTe$_2$ increases monotonically
+with temperature because of the dominance of resistivitylike behavior. By
+contrast, a very weak temperature dependence is found for the damping frequency
+of a single layer, which is attributed to strong surface scattering in this
+highly confined geometry. A systematic study of the damping anisotropy reveals
+that orientational anisotropy is present in both bulk and single-layer
+Fe3GeTe2. Rotational anisotropy is significant at low temperatures for both the
+bulk and a single layer and is gradually diminished by temperature-induced
+disorder. The rotational anisotropy can be significantly enhanced by up to 430%
+in gated single-layer Fe$_3$GeTe$_2$.",2210.08429v1
+2023-01-30,Constraining the Surface Curvature of an Anisotropic Neutron Star,"The anisotropy of pressure arises due to the various complex phenomena that
+happen inside the neutron star (NS). In this study, we calculate the degree of
+anisotropy inside the NS using the scalar pressure anisotropy model.
+Macroscopic properties such as mass, radius, compactness, redshift, tidal
+deformability, the moment of inertia, and surface curvature (SC) are computed
+for the anisotropic NS with the equation of states spanning from relativistic
+to nonrelativistic cases. The variation of SC as the functions of the
+above-mentioned quantities are computed by changing the degree of anisotropy.
+Pressure anisotropy has significant effects on the magnitude of SC. The
+universal relations between the canonical SC$-\Lambda$ and SC$-\bar{I}$ are
+studied. From the GW170817 tidal deformability data constraints on SC are found
+to be SC$_{1.4}(10^{14}) = 3.44_{-1.0}^{+0.4}, 2.85_{-1.20}^{+0.62}, \ {\rm
+and} \ 2.52_{-1.02}^{+0.61}$ for $\lambda_{\rm BL} = 0.0, 1.0$, and $2.0$
+respectively.",2301.12673v2
+2023-03-14,Cosmic Microwave Background anisotropies generated by cosmic strings with small-scale structure,"We study the impact of kinks on the cosmic microwave background (CMB)
+anisotropies generated by cosmic string networks. To do so, we extend the
+Unconnected Segment Model to describe the stress-energy tensor of a network of
+cosmic strings with kinks and implement this extension in CMBACT to compute the
+CMB anisotropies generated by these wiggly string networks. Our results show
+that the inclusion of kinks leads, in general, to an enhancement of the
+temperature and polarization angular power spectra, when compared to those
+generated by cosmic string networks without small-scale structure with the same
+energy density, on scales corresponding to the distance between kinks. This
+enhancement, that is more prominent in the case of the temperature
+anisotropies, is essentially caused by a significant increase of the
+vector-mode anisotropies, since kinks, due to their shape, generate vortical
+motions of matter -- a phenomenon that is not taken into account when resorting
+to an effective description of wiggly cosmic strings.",2303.07548v2
+2023-05-22,Fluid pulsation modes and tidal deformability of anisotropic strange stars in light of the GW$170817$ event,"The effects of the anisotropy on the fluid pulsation modes adopting the
+so-called Cowling approximation and tidal deformability of strange quark stars
+are investigated by using the numerical integration of the hydrostatic
+equilibrium, nonradial oscillations, and tidal deformability equations, being
+these equations modified from their standard form to include the anisotropic
+effects. The fluid matter inside the compact stars is described by the MIT bag
+model equation of state. For the anisotropy profile, we consider a local
+anisotropy that is both regular at the center and null at the star's surface.
+We find that the effect of the anisotropy is reflected in the fluid pulsation
+modes and tidal deformability. Finally, we analyze the correlation between the
+tidal deformability of the GW$170817$ event with the anisotropy.",2305.13468v2
+2023-07-07,Effects of anisotropy on the high field magnetoresistance of Weyl semimetals,"We study the effects of anisotropy on the magnetoresistance of Weyl
+semimetals (WSMs) in the ultraquantum regime. We utilize the fact that many
+Weyl semimetals are approximately axially anisotropic. We find that anisotropy
+manifests itself in the strong dependence of the magnetoresistance on the polar
+and azimuthal angles determining the orientation of the anisotropy axis with
+respect to the applied magnetic field and electric current. We also predict
+that the ratio of magnetoresistances in the geometries, where the magnetic
+field and anisotropy axes are aligned and where they are orthogonal, scales as
+$(v_\bot/v_\parallel)^2$ where $v_\bot$ and $v_\parallel$ are the corresponding
+Fermi velocities.",2307.03772v1
+2023-07-18,Measuring Scale-dependent Shape Anisotropy by Coarse-Graining: Application to Inhomogeneous Rayleigh-Taylor Turbulence,"We generalize the `filtering spectrum' [1] to probe scales along different
+directions by spatial coarse-graining. This multi-dimensional filtering
+spectrum quantifies the spectral content of flows that are not necessarily
+homogeneous. From multi-dimensional spectral information, we propose a simple
+metric for shape anisotropy at various scales. The method is applied to
+simulations of 2D and 3D Rayleigh-Taylor (RT) turbulence, which is
+inhomogeneous and anisotropic. We show that 3D RT has clear shape anisotropy at
+large scales with approximately $4:3$ vertical to horizontal aspect ratio, but
+tends toward isotropy at small scales as expected [2,3,4]. In sharp contrast,
+we find that RT in 2D simulations, which are still the main modeling framework
+for many applications, is isotropic at large scales and its shape anisotropy
+increases at smaller scales where structures tend to be horizontally elongated.
+While this may be surprising, it is consistent with recent results in [5];
+large-scale isotropy in 2D RT is due to the generation of a large-scale
+overturning circulation via an upscale cascade, while small scale anisotropy is
+due to the stable stratification resultant from such overturning and the
+inefficient mixing in 2D.",2307.08918v2
+2023-09-11,Magnetic anisotropy driven by ligand in 4d transition metal oxide SrRuO3,"The origin of magnetic anisotropy in magnetic compounds is a longstanding
+issue in solid state physics and nonmagnetic ligand ions are considered to
+contribute little to magnetic anisotropy. Here, we introduce the concept of
+ligand driven magnetic anisotropy in a complex transition-metal oxide. We
+conducted X ray absorption and X ray magnetic circular dichroism spectroscopies
+at the Ru and O edges in the 4d ferromagnetic metal SrRuO3. Systematic
+variation of the sample thickness in the range below 10 nm allowed us to
+control the localization of Ru 4d t2g states, which affects the magnetic
+coupling between the Ru and O ions. We found that the orbital magnetization of
+the ligand induced via hybridization with the Ru 4d orbital determines the
+magnetic anisotropy in SrRuO3.",2309.05228v2
+2023-10-24,Cubic anisotropy of hole Zeeman splitting in semiconductor nanocrystals,"We study theoretically cubic anisotropy of Zeeman splitting of a hole
+localized in semiconductor nanocrystal. This anisotropy originates from three
+contributions: crystallographic cubically-symmetric spin and kinetic energy
+terms in the bulk Luttinger Hamiltonian and the spatial wave function
+distribution in a cube-shaped nanocrystal. From symmetry considerations, an
+effective Zeeman Hamiltonian for the hole lowest even state is introduced,
+containing a spherically symmetric and a cubically symmetric term. The values
+of these terms are calculated numerically for spherical and cube-shaped
+nanocrystals as functions of the Luttinger Hamiltonian parameters. We
+demonstrate that the cubic shape of the nanocrystal and the cubic anisotropy of
+hole kinetic energy (so called valence band warping) significantly affect
+effective $g$ factors of hole states. In both cases, the effect comes from the
+cubic symmetry of the hole wave functions in zero magnetic field. Estimations
+for the effective $g$ factor values in several semiconductors with zinc-blende
+crystal lattices are made. Possible experimental manifestations and potential
+methods of measurement of the cubic anisotropy of the hole Zeeman splitting are
+suggested.",2310.15876v1
+2023-11-10,The Shape of Learning: Anisotropy and Intrinsic Dimensions in Transformer-Based Models,"In this study, we present an investigation into the anisotropy dynamics and
+intrinsic dimension of embeddings in transformer architectures, focusing on the
+dichotomy between encoders and decoders. Our findings reveal that the
+anisotropy profile in transformer decoders exhibits a distinct bell-shaped
+curve, with the highest anisotropy concentrations in the middle layers. This
+pattern diverges from the more uniformly distributed anisotropy observed in
+encoders. In addition, we found that the intrinsic dimension of embeddings
+increases in the initial phases of training, indicating an expansion into
+higher-dimensional space. Which is then followed by a compression phase towards
+the end of training with dimensionality decrease, suggesting a refinement into
+more compact representations. Our results provide fresh insights to the
+understanding of encoders and decoders embedding properties.",2311.05928v2
+2024-01-08,Atom-by-Atom Mapping and Understanding of In-Plane Anisotropy in GaTe,"Main-group chalcogenides with layered crystal structures and high in-plane
+anisotropy are attracting increasing interest for a range of practical
+applications. The III-VI semiconductor, monoclinic gallium monotelluride
+(m-GaTe), has been recently used in high-sensitivity
+photodetectors/phototransistors and electronic memory applications due to its
+anisotropic properties yielding superior optical and electrical performance.
+Despite these applications, the origin of such anisotropy, namely the complex
+structural and bonding environments in GaTe nanostructures remain to be fully
+understood. In the present work, we report a comprehensive atomic-scale
+characterization of m-GaTe by state-of-the-art element-resolved atomic-scale
+microscopy experiments. By performing imaging for two different view
+directions, we are able to directly measure the in-plane anisotropy of m-GaTe
+at the sub-Angstrom level, and show that it compares well with the results of
+first-principles modeling. Quantum-chemical bonding analyses provide a detailed
+picture of the atomic neighbor interactions within the layers, revealing that
+vertical Ga-Ga homopolar bonds get stronger when they are distorted and
+rotated, inducing the strong in-plane anisotropy.",2401.03731v1
+2024-01-18,Realistic Anisotropic Neutron Stars: Pressure Effects,"In this paper, we study the impact of anisotropy on neutron stars with
+different equations of state, which have been modeled by a piecewise polytropic
+function with continuous sound speed. Anisotropic pressure in neutron stars is
+often attributed to interior magnetic fields, rotation, and the presence of
+exotic matter or condensates. We quantify the presence of anisotropy within the
+star by assuming a quasi-local relationship. We find that the radial and
+tangential sound velocities constrain the range of anisotropy allowed within
+the star. As expected, the anisotropy affects the macroscopic properties of
+stars, and it can be introduced to reconcile them with astrophysical
+observations. For instance, the maximum mass of anisotropic neutron stars can
+be increased by up to 15\% compared to the maximum mass of the corresponding
+isotropic configuration. This allows neutron stars to reach masses greater than
+$2.5M_\odot$, which may explain the secondary compact object of the GW190814
+event. Additionally, we propose a universal relation for the binding energy of
+an anisotropic neutron star as a function of the star's compactness and the
+degree of anisotropy.",2401.10311v1
+2024-03-20,Hydrodynamics of a disk in a thin film of weakly nematic fluid subject to linear friction,"To make progress towards the development of a theory on the motion of
+inclusions in thin structured films and membranes, we here consider as an
+initial step a circular disk in a two-dimensional, uniaxially anisotropic fluid
+layer. We assume overdamped dynamics, incompressibility of the fluid, and
+global alignment of the axis of anisotropy. Motion within this layer is
+affected by additional linear friction with the environment, for instance, a
+supporting substrate. We investigate the induced flows in the fluid when the
+disk is translated parallel or perpendicular to the direction of anisotropy.
+Moreover, expressions for corresponding mobilities and resistance coefficients
+of the disk are derived. Our results are obtained within the framework of a
+perturbative expansion in the parameters that quantify the anisotropy of the
+fluid. Good agreement is found for moderate anisotropy when compared to
+associated results from finite-element simulations. At pronounced anisotropy,
+the induced flow fields are still predicted qualitatively correctly by the
+perturbative theory, although quantitative deviations arise. We hope to
+stimulate with our investigations corresponding experimental analyses, for
+example, concerning fluid flows in anisotropic thin films on uniaxially rubbed
+supporting substrates.",2403.13755v1
+2012-10-04,Structural and Correlation Effects in the Itinerant Insulating Antiferromagnetic Perovskite NaOsO3,"The orthorhombic perovskite NaOsO3 undergoes a continuous metal-insulator
+transition (MIT), accompanied by antiferromagnetic (AFM) order at T_N=410 K,
+suggested to be an example of the rare Slater (itinerant) MIT. We study this
+system using ab initio and related methods, focusing on the origin and nature
+of magnetic ordering and the MIT. The rotation and tilting of OsO6 octahedra in
+the GdFeO3 structure result in moderate narrowing the band width of the t_{2g}
+manifold, but sufficient to induce flattening of bands and AFM order within the
+local spin density approximation (LSDA), where it remains metallic but with a
+deep pseudogap. Including on-site Coulomb repulsion U, at U_c ~2 eV a MIT
+occurs only in the AFM state. Effects of spin-orbit coupling (SOC) on the band
+structure seem minor as expected for a half-filled $t_{2g}^{3}$ shell, but SOC
+doubles the critical value U_c necessary to open a gap and also leads to large
+magnetocrystalline energy differences in spite of normal orbital moments no
+greater than 0.1$\mu_B$. Our results are consistent with a Slater MIT driven by
+magnetic order, induced by a combination of structurally-induced band narrowing
+and moderate Coulomb repulsion, with SOC necessary for a full picture. Strong
+p-d hybridization reduces the moment, and when bootstrapped by the reduced
+Hund's rule coupling (proportional to the moment) gives a calculated moment of
+~1 $\mu_B$, consistent with the observed moment and only a third of the formal
+$d^3$ value. We raise and discuss one important question: since this AFM
+ordering is at q=0 (in the 20 atom cell) where nesting is a moot issue, what is
+the microscopic driving force for ordering and the accompanying MIT?",1210.1286v2
+1993-03-26,The Imprint of Gravitational Waves on the Cosmic Microwave Background,"Long-wavelength gravitational waves can induce significant temperature
+anisotropy in the cosmic microwave background. Distinguishing this from
+anisotropy induced by energy density fluctuations is critical for testing
+inflationary cosmology and theories of large-scale structure formation. We
+describe full radiative transport calculations of the two contributions and
+show that they differ dramatically at angular scales below a few degrees. We
+show how anisotropy experiments probing large- and small-angular scales can
+combine to distinguish the imprint due to gravitational waves.",9303014v1
+1993-10-29,Reionization and Cosmic Microwave Anisotropies,"The effects of reionization, occurring after standard recombination in cold
+dark matter-dominated models, on CMB anisotropies are investigated. Late-time
+reionization reduces the CMB anisotropies, in particular, on degree scales. It
+is found that constraints on cold dark matter-dominated models from the highest
+frequency channel of the 9-point South Pole data are significantly relaxed for
+models which are consistent with Big Bang nucleosynthesis if reionization is
+assumed to have occurred by redshift $\sim 20.$",9310051v1
+1994-05-11,Microwave background anisotropy in low-$Ω_0$ inflationary models and the scale of homogeneity in the Universe,"We study the microwave background anisotropy due to superhorizon-size
+perturbations (the Grischuk-Zel'dovich effect) in open universes with negative
+spatial curvature. Using COBE results on the low-order temperature multipole
+moments, we find that if the homogeneity of the observable Universe arises from
+an early epoch of inflation, the present density parameter cannot differ from
+unity by more than the observed quadrupole anisotropy, $|1-\Omega_0| \alt Q
+\simeq 5\times 10^{-6}$. Thus, inflation models with low $\Omega_0$ either do
+not fit the microwave background observations or they do not solve the horizon
+problem.",9405024v1
+1994-07-14,Cosmic Microwave Background Radiation Anisotropy Induced by Cosmic Strings,"We report on a current investigation of the anisotropy pattern induced by
+cosmic strings on the cosmic microwave background radiation (MBR). We have
+numerically evolved a network of cosmic strings from a redshift of $Z = 100$ to
+the present and calculated the anisotropies which they induce. Based on a
+limited number of realizations, we have compared the results of our simulations
+with the observations of the COBE-DMR experiment. We have obtained a
+preliminary estimate of the string mass-per-unit-length $\mu$ in the cosmic
+string scenario.",9407042v1
+1994-07-20,Cosmic Microwave Background Anisotropies and the Geometry of the Universe,"In this talk, I review some recent work on cosmic microwave background (CMB)
+anisotropies in an open universe. I emphasize that the observed CMB
+anisotropies are still consistent with a low value of $\Omega$, and I address
+the question of whether future CMB measurements will be able to provide
+information on the geometry of the Universe.",9407062v1
+1994-10-12,Foreground Contributions to 0.2-2 Degree CMB Anisotropies,"We examine the extent to which galactic and extragalactic foregrounds can
+hamper the detection of primordial Cosmic Microwave Background (CMB)
+anisotropies. We limit our discussion to intermediate angular scales,
+$10^{\prime}\lsim \theta \lsim 2^{\circ}$, since many current as well as future
+experiments have been designed to map CMB anisotropies at these angular scales.
+In fact, scales of $\gsim 10^{\prime}$ are of crucial importance to test both
+the conditions in the early Universe and current theories of the gravitational
+collapse.",9410037v1
+1995-01-06,"LIMITS ON ANISOTROPY AND INHOMOGENEITY FROM THE COSMIC BACKGROUND RADIATION,","We consider directly the equations by which matter imposes anisotropies on
+freely propagating background radiation, leading to a new way of using
+anisotropy measurements to limit the deviations of the Universe from a
+Friedmann-Robertson-Walker (FRW) geometry. This approach is complementary to
+the usual Sachs-Wolfe approach: the limits obtained are not as detailed, but
+they are more model-independent. We also give new results about combined
+matter-radiation perturbations in an almost-FRW universe, and a new exact
+solution of the linearised equations.",9501016v1
+1995-05-22,Echoes of Gravity,"The study of anisotropies in the Cosmic Microwave Background radiation is
+progressing at a phenomenal rate, both experimentally and theoretically. These
+anisotropies can teach us an enormous amount about the way that fluctuations
+were generated and the way they subsequently evolved into the clustered
+galaxies which are observed today. In particular, on sub-degree scales the rich
+structure in the anisotropy spectrum is the consequence of gravity-driven
+acoustic oscillations occurring before the matter in the universe became
+neutral. The frozen-in phases of these sound waves imprint a dependence on many
+cosmological parameters, that we may be on the verge of extracting.",9505102v1
+1995-06-20,Gravitational Lensing and Anisotropies of CBR on the Small Angular Scales,"We investigate the effect of gravitational lensing, produced by linear
+density perturbations, for anisotropies of the Cosmic Background Radiation
+(CBR) on scales of arcminutes. In calculations, a flat universe ($\Omega=1$)
+and the Harrison-Zel'dovich spectrum ($n=1$) are assumed. The numerical results
+show that on scales of a few arcminutes, gravitational lensing produces only
+negligible anisotropies in the temperature of the CBR. Our conclusion disagrees
+with that of Cay\'{o}n {\it et al.} who argue that the amplification of $\Delta
+T/T$ on scales $\le 3'$ may even be larger than 100\%.",9506102v1
+1995-12-23,CMB Anisotropy in COBE-DMR-Normalized Flat $Λ$ CDM Cosmogony,"We compute the cosmic microwave background (CMB) anisotropy in a low-density,
+flat, cosmological constant, cold dark matter model which is normalized to the
+two-year COBE DMR sky map. Although conclusions regarding model viability must
+remain tentative until systematic effects are better understood, there are mild
+indications that these models have more intermediate scale power than is
+indicated by presently available CMB anisotropy observational data, with old
+($t_0 \geq 15-16$Gyr), high baryon density ($\Omega_B \geq 0.0175 h^{-2}$), low
+density ($\Omega_0 \sim 0.2-0.4$) models doing the worst.",9512157v1
+1996-04-28,The Physics of Microwave Background Anisotropies,"Cosmic microwave background anisotropies provide a vast amount of
+cosmological information. Their full physical content and detailed structure
+can be understood in a simple and intuitive fashion through a systematic
+investigation of the individual mechanisms for anisotropy formation.",9604166v1
+1996-05-20,How Anisotropic is our Universe?,"Large-scale cosmic microwave background anisotropies in homogeneous, globally
+anisotropic cosmologies are investigated. We perform a statistical analysis in
+which the four-year data from the Cosmic Background Explorer satellite is
+searched for the specific anisotropy patterns predicted by these models and
+thereby set definitive upper limits on the amount of shear, $(\sigma/H)_0$ and
+vorticity, $(\omega/H)_0$, which are orders of magnitude stronger than previous
+constraints. We comment on how these results might impact our understanding of
+primordial global anisotropy.",9605123v1
+1996-09-10,The Damping Tail of CMB Anisotropies,"By decomposing the damping tail of CMB anisotropies into a series of transfer
+functions representing individual physical effects, we provide ingredients that
+will aid in the reconstruction of the cosmological model from small-scale CMB
+anisotropy data. We accurately calibrate the model-independent effects of
+diffusion and reionization damping which provide potentially the most robust
+information on the background cosmology. Removing these effects, we uncover
+model-dependent processes such as the acoustic peak modulation and
+gravitational enhancement that can help distinguish between alternate models of
+structure formation and provide windows into the evolution of fluctuations at
+various stages in their growth.",9609079v1
+1996-10-24,Small-angle anisotropies in the CMBR from active sources,"We consider the effects of photon diffusion on the small-angle microwave
+background anisotropies due to active source models. We find that fluctuations
+created just before the time of last scattering allow anisotropy to be created
+on scales much smaller than allowed by standard Silk damping. Using simple
+models for string and texture structure functions as examples, we illustrate
+the differences in the angular power spectrum at scales of order a few
+arcminutes. In particular, we find that the Doppler peak heights are modified
+by 10-50% and the small-angle fall-off is power law rather than exponential.",9610197v1
+1996-12-20,Microwave Background Anisotropies Induced by Global Scalar Fields: The Large N Limit,"We present an analysis of CMB anisotropies induced by global scalar fields in
+the large N limit. In this limit, the CMB anisotropy spectrum can be determined
+without cumbersome 3D simulations. We determine the source functions and their
+unequal time correlation functions and show that they are quite similar to the
+corresponding functions in the texture model. This leads us to the conclusion
+that the large N limit provides a 'cheap approximation' to the texture model of
+structure formation.",9612202v1
+1997-02-19,Cosmic microwave background measurements can discriminate among inflation models,"Quantum fluctuations during inflation may be responsible for temperature
+anisotropies in the cosmic microwave background (CMB). Observations of CMB
+anisotropies can be used to falsify many currently popular models. In this
+paper we discuss the prospectus for observations of CMB anisotropies at the
+accuracy of planned satellite missions to reject currently popular inflation
+models and to provide some direction for model building.",9702166v1
+1997-02-21,Using SuZIE arcminute-scale CMB anisotropy data to probe open and flat-ΛCDM cosmogonies,"We use arcminute-scale data from the Sunyaev-Zel'dovich Infrared Experiment
+to set limits on anisotropies in the cosmic microwave background radiation in
+open and spatially-flat-Lambda cold dark matter cosmogonies. There are no
+2-sigma detections for the models tested. The upper limits obtained are
+consistent with the amplitude of anisotropy detected by the COBE/DMR
+experiment.",9702186v1
+1998-07-09,Microwave Background Anisotropies from Alfven waves,"We investigate microwave background anisotropies in the presence of
+primordial magnetic fields. We show that a homogeneous field with fixed
+direction can amplify vector perturbations. We calculate the correlations of
+$\delta T/T$ explicitly and show that a large scale coherent field induces
+correlations between $a_{\ell-1,m}$ and $a_{\ell+1,m}$. We discuss constraints
+on amplitude and spectrum of a primordial magnetic field imposed by
+observations of CMB anisotropies.",9807089v1
+2000-02-02,The Cosmic Microwave Background Radiation,"We summarize the theoretical and observational status of the study of the
+Cosmic Microwave Background radiation. Its thermodynamic spectrum is a robust
+prediction of the Hot Big Bang cosmology and has been confirmed
+observationally. There are now 76 observations of Cosmic Microwave Background
+anisotropy, which we present in a table with references. We discuss the
+theoretical origins of these anisotropies and explain the standard jargon
+associated with their observation.",0002044v1
+2000-06-26,Cosmic Microwave Background Radiation anisotropy with primordial magnetic fields,"Galactic magnetic fields are observed of order $\sim 10^{-6}G$, but their
+origin is not definitely known yet. In this paper we consider the primordial
+magnetic fields generated in the early universe and analyse their effects on
+the density perturbations and the CMBR anisotropy. We assume that the random
+magnetic fields have the power law spectrum and satisfy the force-free field
+condition.
+  The peak heights of the CMBR anisotropy are shown to be shifted upward
+depending on the magnetic field strengths relative to the no-magnetic field
+case.",0006357v1
+2000-08-30,Secondary CMB Anisotropies from Cosmological Reionization,"We use numerical simulation of cosmological reionization to calculate the
+secondary CMB anisotropies in a representative flat low density cosmological
+model. We show that the kinetic Sunyaev-Zel'dovich effect (scattering off of
+moving electrons in the ionized intergalactic medium) is dominated by the
+nonlinear hydrodynamic and gravitational evolution of the density and velocity
+fields, rather than the detailed distribution of the ionization fraction
+(``patchy reionization'') on all angular scales. Combining our results with the
+recent calculation of secondary CMB anisotropies by Springel et al., we are
+able to accurately predict the power spectrum of the kinetic SZ effect on
+almost all angular scales.",0008469v3
+2000-10-31,Reproducing the observed Cosmic microwave background anisotropies with causal scaling seeds,"During the last years it has become clear that global O(N) defects and U(1)
+cosmic strings do not lead to the pronounced first acoustic peak in the power
+spectrum of anisotropies of the cosmic microwave background which has recently
+been observed to high accuracy. Inflationary models cannot easily accommodate
+the low second peak indicated by the data. Here we construct causal scaling
+seed models which reproduce the first and second peak. Future, more precise CMB
+anisotropy and polarization experiments will however be able to distinguish
+them from the ordinary adiabatic models.",0010633v2
+2000-11-28,Peculiarities of anisotropy and polarization as an indicator of noises in the CMB maps,"We discuss some new problems of the modern cosmology which arose after the
+BOOMERANG and MAXIMA-1 successful missions. Statistics of high peaks of the CMB
+anisotropy is analyzed and we discuss possible inner structure of such peaks in
+the observational data of future MAP and PLANCK missions. We have investigated
+geometrical and statistical properties of the CMB polarization around such high
+isolated peaks of anisotropy in the presence of a polarized pixel noise and
+point sources. The structure of polarization fields in the vicinity of singular
+points with zero polarization is very sensitive to the level of pixel noises
+and point sources in the CMB maps.",0011521v1
+2000-12-11,The MAP satellite mission to map the CMB anisotropy,"The Microwave Anisotropy Probe (MAP) satellite is scheduled to launch in
+mid-2001. MAP's goal is to produce a map of the anisotropy in the cosmic
+microwave background of unprecedented accuracy and precision. The guiding
+design principle has been the minimization of systematic effects. The
+instrument design and mapping strategy work in concert to take advantage of the
+unique opportunities afforded by deep space. We give an overview of the mission
+and compare the projected MAP error bars to recent measurements.",0012214v1
+2001-07-19,Observing the CMB with the AMiBA,"I discuss the capabilities and limitations of the AMiBA for imaging CMB
+anisotropies. Michael Kesteven (ATNF-CSIRO) has proposed drift-scanning as an
+observing strategy for measuring and rejecting any instrumental response that
+the close-packed interferometers may have to the local environment. The
+advantages of mosaic imaging CMB anisotropies using a co-mounted
+interferometric array in a drift-scanning observing mode are discussed. A
+particular case of mosaic imaging a sky strip using a two-element AMiBA
+prototype interferometer is considered and the signal-to-noise ratio in the
+measurement of sky anisotropy using this observing strategy is analysed.",0107363v1
+2001-08-17,Small Scale Anisotropies of UHECRs from Super-Heavy Halo Dark Matter,"The decay of very heavy metastable relics of the Early Universe can produce
+ultra-high energy cosmic rays (UHECRs) in the halo of our own Galaxy. In this
+model, no Greisen-Zatsepin-Kuzmin cutoff is expected because of the short
+propagation distances. We show here that, as a consequence of the hierarchical
+build up of the halo, this scenario predicts the existence of small scale
+anisotropies in the arrival directions of UHECRs, in addition to a large scale
+anisotropy, known from previous studies. We also suggest some other observable
+consequences of this scenario which will be testable with upcoming experiments,
+as Auger, EUSO and OWL.",0108288v1
+2001-08-27,ATCA and CMB anisotropies,"Australia Telescope Compact Array (ATCA) observations in sky regions selected
+to be low in foreground confusion have been used to infer limits on
+arcmin-scale CMB anisotropy in total intensity and polarization. These deep
+searches have, hitherto, been made using the East-West ATCA in an ultra-compact
+1-D array configuration and in the highest available frequency band at 3-cm
+wavelength. The ATCA is being upgraded for operation at mm wavelengths and in
+2-D array configurations: the enhanced capabilities present a new opportunity
+for pursuing CMB anisotropy related observations with reduced foreground
+confusion and at smaller angular scales.",0108409v1
+2001-09-10,Principal Component Analysis of the Cosmic Microwave Background Anisotropies: Revealing The Tensor Degeneracy,"A principal component analysis of cosmic microwave background (CMB)
+anisotropy measurements is used to investigate degeneracies among cosmological
+parameters. The results show that a degeneracy with tensor modes -- the `tensor
+degeneracy' -- dominates uncertainties in estimates of the baryon and cold dark
+matter densities, omega_b = Omega_b h2, omega_c = \Omega_c h^2, from an
+analysis of CMB anisotropies alone. The principal component analysis agrees
+well with a maximum likelihood analysis of the observations, identifying the
+main degeneracy directions and providing an impression of the effective
+dimensionality of the parameter space.",0109151v1
+2001-12-11,The primordial baryonic clouds and their contribution to the CMB anisotropy and polarization formation,"We discuss possible distortions of the ionization history of the Universe in
+the model with small scale baryonic clouds. The corresponding scales of the
+clouds are much smaller than the typical galactic mass scales. These clouds are
+considered in a framework of the cosmological model with the isocurvature and
+adiabatic perturbations. In this model the baryonic clouds do not influence on
+the cosmic microwave background anisotropy formation directly as an additional
+sources of perturbations, but due to change of the kinetics of the hydrogen
+recombination . We also study the corresponding distortions of the anisotropy
+and polarization power spectra in connection with the launched MAP and future
+PLANCK missions.",0112247v1
+2002-07-31,Braneworld Tensor Anisotropies in the CMB,"Cosmic microwave background (CMB) observations provide in principle a
+high-precision test of models which are motivated by M theory. We set out the
+framework of a program to compute the tensor anisotropies in the CMB that are
+generated in braneworld models. In the simplest approximation, we show the
+braneworld imprint as a correction to the power spectra for standard
+temperature and polarization anisotropies.",0208015v2
+2003-03-10,Anisotropy in the angular distribution of the long gamma-ray bursts?,"The gamma-ray bursts detected by the BATSE instrument may be separated into
+""short"", ""intermediate"" and ""long"" subgroups. Previous statistical tests found
+an anisotropic sky-distribution on large angular scales for the intermediate
+subgroup, and probably also for the short subgroup. In this article the
+description and the results of a further statistical test - namely the nearest
+neighbour analysis - are given. Surprisingly, this test gives an anisotropy for
+the long subgroup on small angular scales. The discussion of this result
+suggests that this anisotropy may be real.",0303207v1
+2003-12-15,Large scale cosmic-ray anisotropy with KASCADE,"The results of an analysis of the large scale anisotropy of cosmic rays in
+the PeV range are presented. The Rayleigh formalism is applied to the right
+ascension distribution of extensive air showers measured by the KASCADE
+experiment.The data set contains about 10^8 extensive air showers in the energy
+range from 0.7 to 6 PeV. No hints for anisotropy are visible in the right
+ascension distributions in this energy range. This accounts for all showers as
+well as for subsets containing showers induced by predominantly light
+respectively heavy primary particles. Upper flux limits for Rayleigh amplitudes
+are determined to be between 10^-3 at 0.7 PeV and 10^-2 at 6 PeV primary
+energy.",0312375v1
+2004-03-25,Hyperbolic Universes with a Horned Topology and the CMB Anisotropy,"We analyse the anisotropy of the cosmic microwave background (CMB) in
+hyperbolic universes possessing a non-trivial topology with a fundamental cell
+having an infinitely long horn. The aim of this paper is twofold. On the one
+hand, we show that the horned topology does not lead to a flat spot in the CMB
+sky maps in the direction of the horn as stated in the literature. On the other
+hand, we demonstrate that a horned topology having a finite volume could
+explain the suppression of the lower multipoles in the CMB anisotropy as
+observed by COBE and WMAP.",0403597v2
+2004-11-01,Are Clusters as Indicators of the Cosmic Ray Anisotropy ?,"The clusters (doublets) in ultrahigh energy cosmic rays are considered based
+on Yakutsk and AGASA extensive air shower array data. The problem of cluster
+origin is discussed. It is found that arrival directions of the clusters can
+point to a cosmic ray anisotropy. As a result of analysis of clusters, the
+conclusion on composition and origin of ultrahigh energy cosmic rays has been
+made.",0411022v1
+2004-12-02,Indication for Primordial Anisotropies in the Neutrino Background from WMAP and SDSS,"We demonstrate that combining Cosmic Microwave Background anisotropy
+measurements from the 1st year WMAP observations with clustering data from the
+SLOAN galaxy redshift survey yields an indication for primordial anisotropies
+in the cosmological Neutrino Background.",0412066v2
+2005-12-12,The Big Bang Problems: Anisotropy of z <= 6 Redshifts,"The three-dimensional space distribution of 48921 quasars and 16113 Seyfert
+galaxies with redshifts z <= 6 is investigated. The global anisotropy caused by
+the shift of the observer place by \simeq 50 Mpc from a center of their
+symmetry (supposed center of the Metagalaxy) to the side of the vector with
+equatorial coordinates \alpha \simeq 13 degrees and \delta \simeq 70 degrees
+has been found in the placement of these objects. In the opposite direction
+there exists the extensive region where the progressive decrease of redshifts
+up to a minimum (near \alpha \simeq 193 degrees, \delta \simeq -70 degrees) is
+observed. The influence of gravitational potential and possible rotation of the
+Metagalaxy on the anisotropy of redshifts of the cosmological objects has been
+considered.",0512276v1
+2006-09-14,CMB Anisotropies from Outflows in Lyman Break Galaxies,"Thomson scattering of the Cosmic Microwave Background (CMB) on moving
+electrons in the outflows of Lyman Break Galaxies (LBGs) at redshifts 2-8
+contributes to the small-scale CMB anisotropies. The net effect produced by
+each outflow depends on its level of deviation from spherical symmetry, caused
+either by an anisotropic energy injection from the nuclear starburst or quasar
+activity, or by an inhomogeneous intergalactic environment. We find that for
+plausible outflow parameters consistent with spectroscopic observations of
+LBGs, the induced CMB anisotropies on arcminute scales reach up to $\sim 1
+\mu$K, comparable to the level produced during the epoch of reionization.",0609399v1
+2006-10-05,Anisotropy studies around the galactic center,"We present the first results for anisotropy searches around the galactic
+center at EeV energies using data from the Pierre Auger Observatory. Our
+analysis, based on a substantially larger data set, do not support previous
+claim of anisotropy found in this region by the AGASA and Sugar experiment.
+Furthermore we place un upper limit on a possible point like source located at
+the galactic center which exclude several scenarios predicting neutron sources
+in this location.",0610160v1
+2006-10-05,Cosmic Microwave Background anisotropies: the power spectrum and beyond,"Most of the cosmological information extracted from the CMB has been obtained
+through the power spectrum, however there is much more to be learnt from the
+statistical distribution of the temperature random field. We review some recent
+developments in the study of the Cosmic Microwave Background (CMB) anisotropies
+and present a description of the novel tools developed to analyse the
+properties of the CMB anisotropies beyond the power spectrum.",0610162v1
+2006-10-29,Anisotropies and clustering of extragalactic cosmic rays,"Deviations from isotropy have been a key tool to identify the sources and the
+primary type of cosmic rays (CRs) at low energies. We argue that anisotropies
+due to blind regions induced by the Galactic magnetic field, the cosmological
+Compton-Getting effect, medium-scale anisotropies reflecting the large-scale
+distribution of CR sources and the small-scale clustering of the CR arrival
+directions at the highest energies may play the same role for extragalactic
+CRs.",0610862v1
+1994-10-25,Thermal Conductivity Anisotropy in Superconducting $UPt_3$,"Recent thermal conductivity measurements on $UPt_3$ single crystals by
+Lussier et al. indicate the existence of a strong b--c anisotropy in the
+superconducting state. We calculate the thermal conductivity in various
+unconventional candidate states appropriate for the $UPt_3$ ``B phase"" and
+compare with experiment, specifically the $E_{2u}$ and $E_{1g}$ $(1,i)$ states
+predicted in some Ginzburg-Landau analyses of the phase diagram. For the
+simplest realizations of these states over spherical or ellipsoidal Fermi
+surfaces, the normalized $E_{2u}$ conductivity is found, surprisingly, to be
+completely isotropic. We discuss the effects of inelastic scattering and
+realistic Fermi surface anisotropy, and deduce constraints on the symmetry
+class of the $UPt_3$ ground state.",9410087v1
+1996-06-18,Partially Solvable Anisotropic t-J Model with Long-Range Interactions,"A new anisotropic t-J model in one dimension is proposed which has long-range
+hopping and exchange. This t-J model is only partially solvable in contrast to
+known integrable models with long-range interaction. In the high-density limit
+the model reduces to the XXZ chain with the long-range exchange. Some exact
+eigenfunctions are shown to be of Jastrow-type if certain conditions for an
+anisotropy parameter are satisfied. The ground state as well as the excitation
+spectrum for various cases of the anisotropy parameter and filling are derived
+numerically. It is found that the Jastrow-type wave function is an excellent
+trial function for any value of the anisotropy parameter.",9606128v1
+1997-02-26,Effect of randomness and anisotropy on Turing patterns in reaction-diffusion systems,"We study the effect of randomness and anisotropy on Turing patterns in
+reaction-diffusion systems. For this purpose, the Gierer-Meinhardt model of
+pattern formation is considered. The cases we study are: (i)randomness in the
+underlying lattice structure, (ii)the case in which there is a probablity p
+that at a lattice site both reaction and diffusion occur, otherwise there is
+only diffusion and lastly, the effect of (iii) anisotropic and (iv) random
+diffusion coefficients on the formation of Turing patterns. The general
+conclusion is that the Turing mechanism of pattern formation is fairly robust
+in the presence of randomness and anisotropy.",9702230v1
+1997-03-24,A theoretical investigation of the specific heat of superlattices in a magnetic field,"We analyze the specific heat variations as a function of an external magnetic
+field of a simple model of superlattice that includes (i) in--plane
+ferromagnetic exchange, (ii) interplane ferromagnetic exchange, (iii) dipolar
+interactions, (iv) magnetocristalline anisotropy. The calculations are carried
+out at the spin wave level. The interplay between the existence of a canting
+transition and the anisotropy of the structure generates non trivial behavior
+for the spin wave contribution to the low temperature specific heat as a
+function of an external magnetic field when dipolar interactions and
+magnetocristalline anisotropy are taken into account.",9703202v1
+1997-04-14,The Effect of Anisotropy on Vortex Lattice Structure and Flux Flow in d-Wave Superconductors,"We describe effects of anisotropy caused by the crystal lattice in d-wave
+superconductors using effective free energy approach in which only one order
+parameter, the d-wave order parameter field, is used. All the effects of
+rotational symmetry breaking, including that of the s-wave mixing, can be
+parametrized by a single four derivative term. We find solutions for single
+vortex and the vortex lattice. Extending the formalism to include the time
+dependence, effects of anisotropy on moving vortex structure are calculated.
+Both direct and Hall I-V curves as functions of the angle between the current
+and the crystal lattice orientation are obtained.",9704116v1
+1997-06-30,Anisotropy effects in a mixed quantum-classical Heisenberg model in two dimensions,"We analyse a specific two dimensional mixed spin Heisenberg model with
+exchange anisotropy, by means of high temperature expansions and Monte Carlo
+simulations. The goal is to describe the magnetic properties of the compound
+(NBu_{4})_{2}Mn_{2}[Cu(opba)]_{3}\cdot 6DMSO\cdot H_{2}O which exhibits a
+ferromagnetic transition at $T_{c}=15K$. Extrapolating our analysis on the
+basis of renormalisation group arguments, we find that this transition may
+result from a very weak anisotropy effect.",9706298v1
+1997-11-18,Combined effect of nonmagnetic and magnetic scatterers on critical temperatures of superconductors with different gap anisotropy,"The combined effect of nonmagnetic and magnetic defects and impurities on
+critical temperatures of superconductors with different gap anisotropy is
+studied theoretically within the weak coupling limit of the BCS model. An
+expression is derived which relates the critical temperature to relaxation
+rates of charge carriers by nonmagnetic and magnetic scatterers, as well as to
+the coefficient of anisotropy of the superconducting order parameter on the
+Fermi surface. Particular cases of d-wave, (s+d)-wave, and anisotropic s-wave
+superconductors are briefly discussed.",9711175v1
+1998-04-01,Magnetic Reversal on Vicinal Surfaces,"We present a theoretical study of in-plane magnetization reversal for vicinal
+ultrathin films using a one-dimensional micromagnetic model with
+nearest-neighbor exchange, four-fold anisotropy at all sites, and two-fold
+anisotropy at step edges. A detailed ""phase diagram"" is presented that catalogs
+the possible shapes of hysteresis loops and reversal mechanisms as a function
+of step anisotropy strength and vicinal terrace length. The steps generically
+nucleate magnetization reversal and pin the motion of domain walls. No sharp
+transition separates the cases of reversal by coherent rotation and reversal by
+depinning of a ninety degree domain wall from the steps. Comparison to
+experiment is made when appropriate.",9804009v1
+1998-08-26,Evolution of the pairing pseudogap in the spectral function with interplane anisotropy,"We study the pairing pseudogap in the spectral function as a function of
+interplane coupling. The analytical expressions for the self-energy in the
+critical regime are obtained for any degree of anisotropy. The frequency
+dependence of the self-energy is found to be qualitatively different in two and
+three dimensions, and the crossover from two to three dimensional behavior is
+discussed. In particular, by considering the anisotropy of the Fermi velocity
+and gap along the Fermi surface, we can qualitatively explain recent
+photoemission experiments on high temperature superconductors concerning the
+temperature dependent Fermi arcs seen in the pseudogap phase.",9808298v1
+1998-09-25,Absence of anisotropic universal transport in YBCO,"There exists significant in-plane anisotropy between $a$ and $b$ axis for
+various properties in YBCO. However recent thermal conductivity measurement by
+Chiao et al. which confirms previous microwave conductivity measurement by
+Zhang et al., shows no obvious anisotropy in the context of universal
+transport. We give a possible explanation of why the anisotropy is seen in most
+properties but not seen in the universal transport.",9809341v1
+1998-10-19,Polymer Shape Anisotropy and the Depletion Interaction,"We calculate the second and third virial coefficients of the effective
+sphere-sphere interaction due to polymer depletion. By utilizing the anisotropy
+of a typical polymer conformation, we can consider polymers that are roughly
+the same size as the spherical inclusions. We argue that recent experiments can
+confirm this anisotropy.",9810234v2
+1998-12-15,Self-consistent calculation of the autolocalization barrier for quasiparticles in anisotropic crystal,"The energy of the electron wave packet interacting with lattice distortion,
+is considered in anisotropic crystal. Anisotropy of the electron and phonon
+spectra as well as of the electron-phonon interaction are taken into account.
+The height of the barrier between free and self-trapped states is calculated in
+dependence on the anisotropy parameters. The calculation is done numerically,
+using continual aproximation. The analytical solution is obtained for some
+cases of quasi-two and quasi-one-dimensional spectra. Key words: anisotropy;
+polarons; barrier.",9812246v1
+1998-12-16,Quasi-long range order in the random anisotropy Heisenberg model,"The large distance behaviors of the random field and random anisotropy
+Heisenberg models are studied with the functional renormalization group in
+$4-\epsilon$ dimensions. The random anisotropy model is found to have a phase
+with the infinite correlation radius at low temperatures and weak disorder. The
+correlation function of the magnetization obeys a power law $<{\bf m}({\bf
+r}_1) {\bf m}({\bf r}_2)>\sim| {\bf r}_1-{\bf r}_2|^{-0.62\epsilon}$. The
+magnetic susceptibility diverges at low fields as $\chi\sim
+H^{-1+0.15\epsilon}$. In the random field model the correlation radius is found
+to be finite at the arbitrarily weak disorder.",9812280v1
+1999-04-08,Magnetic and quadrupolar order in a one-dimensional ferromagnet with cubic crystal-field anisotropy,"The zero temperature phase diagram of a one-dimensional S=2 Heisenberg
+ferromagnet with single-ion cubic anisotropy is studied numerically using the
+density-matrix renormalization group method. Evidence is found that although
+the model does not involve quadrupolar couplings, there is a purely quadrupolar
+phase for large values of the anisotropy. The phase transition between the
+magnetic and quadrupolar phases is continuous and it seems to be characterized
+by Ising critical exponents.",9904109v1
+1999-05-25,Field-tilt Anisotropy Energy in Quantum Hall Stripe States,"Recently reported giant anisotropy in the longitudinal resistivity of a 2D
+electron system with valence Landau level index $N \ge 2$ has been interpreted
+as a signal of unidirectional charge density wave (UCDW) ground states. We
+report on detailed Hartree-Fock calculations of the UCDW orientation energy
+induced by a tilted magnetic field. We find that for current experimental
+samples stripes are oriented perpendicular to the in-plane field, consistent
+with experiment. For wider 2D electron systems we predict tilt-induced stripe
+states with variable anisotropy energy sign.",9905353v2
+1999-08-31,Four-fold basal plane anisotropy of the nonlocal magnetization of YNi2B2C,"Studies of single crystal YNi2B2C have revealed a four-fold anisotropy of the
+equilibrium magnetization in the square crystallographic basal plane. This pi/2
+periodicity occurs deep in the superconductive mixed state. In this crystal
+symmetry, an ordinary superconductive mass anisotropy (as in usual London
+theory) allows only a constant, isotropic response. In contrast, the
+experimental results are well described by generalized London theory
+incorporating non-local electrodynamics, as needed for this clean,
+intermediate-k superconductor.",9908483v1
+1999-11-01,Competing effects of mass anisotropy and spin Zeeman coupling on the upper critical field of a mixed $d$- and s-wave superconductor,"Based on the linearized Eilenberger equations, the upper critical field
+$(H_{c2})$ of mixed d- and s-wave superconductors has been microscopically
+studied with an emphasis on the competing effects of mass anisotropy and spin
+Zeeman coupling. We find the mass anisotropy always enhance $H_{c2}$ while the
+Zeeman interaction suppresses $H_{c2}$. As required by the thermodynamics, we
+find $H_{c2}$ is saturated at zero temperature. We compare the theoretical
+calculations with recent experimental data of
+YBa$_{2}$Cu$_{3}$O$_{7-+AFw-delta}$.",9910522v1
+2000-03-03,Breakdown of the Onsager reaction field theory in two dimensions,"It is shown that for the spin 1/2 anisotropic Heisenberg model the result for
+the transition temperature is completely insensitive to the anisotropy within
+the Onsager reaction field theory, which yields a vanishing T_c in two
+dimensions, in total conflict with the expected finite T_c, increasing with
+anisotropy. This establishes that the breakdown of the Onsager reaction field
+theory in two dimensions is not limited to the Ising model, but actually
+extends over the whole range of anisotropy. Therefore, for the isotropic case,
+the results of vanishing T_c and exponential dependence of spin correlation
+length should be seen as mere coincidence.",0003040v1
+2001-01-04,Strong anisotropy of superexchange in the copper-oxygen chains of La_{14-x}Ca_{x}Cu_{24}O_{41},"Electron spin resonance data of Cu^{2+} ions in La_{14-x}Ca_{x}Cu_{24}O_{41}
+crystals (x=9,11,12) reveal a very large width of the resonance line in the
+paramagnetic state. This signals an unusually strong anisotropy of ~10% of the
+isotropic Heisenberg superexchange in the Cu-O chains of this compound. The
+strong anisotropy can be explained by the specific geometry of two symmetrical
+90 degree Cu-O-Cu bonds, which boosts the importance of orbital degrees of
+freedom. Our data show the apparent limitations of the applicability of an
+isotropic Heisenberg model to the low dimensional cuprates.",0101040v1
+2001-01-24,Effects of geometric anisotropy on local field distribution: Ewald-Kornfeld formulation,"We have applied the Ewald-Kornfeld formulation to a tetragonal lattice of
+point dipoles, in an attempt to examine the effects of geometric anisotropy on
+the local field distribution. The various problems encountered in the
+computation of the conditionally convergent summation of the near field are
+addressed and the methods of overcoming them are discussed. The results show
+that the geometric anisotropy has a significant impact on the local field
+distribution. The change in the local field can lead to a generalized
+Clausius-Mossotti equation for the anisotropic case.",0101361v1
+2001-03-16,Mean-field theory of magnetic properties of Mn$_x$III$_{1-x}$V semiconductors,"We present a mean-field theory of carrier-induced ferromagnetism in
+Mn$_x$III$_{1-x}$V diluted magnetic semiconductors with a special emphasis
+placed on the magnetic anisotropy. The valence band holes are described using
+the six band Kohn-Luttinger model. We find that the magnetic anisotropy is a
+complicated function of sample parameters such as hole density or strain.
+Results of our numerical simulations are in agreement with magnetic anisotropy
+measurements on samples with both compressive and tensile strains.",0103341v1
+2001-06-15,Real-Space Renormalization Group Study of Effects of Anisotropy on S=1 Random Antiferromagnetic Chain,"We investigate S=1 antiferromagnetic quantum spin chain, whose exchange
+couplings are strongly disordered. By the real-space renomalization group
+method, introduced by Ma, Dasgupta, and Hu, the renormalization group flows are
+analyzed numerically in a plain of the anisotoropy of the exchange coupling vs.
+the staggered magnetic field. As the result, the Heisenberg point, which has a
+zero average of the exchange coupling anisotropy, is specified as the unstable
+fixed point against the anisotropy.",0106289v2
+2001-06-23,Anisotropy of Quasiparticle Lifetimes and the Role of Disorder for Ultrafast Electron Dynamics in Graphite,"Femtosecond time-resolved photoemission of photoexcited electrons in highly
+oriented pyrolytic graphite (HOPG) provides strong evidence for anisotropies of
+quasiparticle (QP) lifetimes. Indicative of such anisotropies is a pronounced
+anomaly in the energy dependence of QP lifetimes between 1.1 eV and 1.5 eV -
+the vicinity of a saddle point in the graphite bandstructure. This is supported
+by recent ab initio calculations and a comparison with experiments on
+defect-enriched HOPG which reveal that disorder, e.g. defects or phonons,
+increases electron energy relaxation rates.",0106486v1
+2001-08-13,Stripes and spin-incommensurabilities are favored by lattice anisotropies,"Structural distortions in cuprate materials give a natural origin for
+anisotropies in electron properties. We study a modified one-band t-J model in
+which we allow for different hoppings and antiferromagnetic couplings in the
+two spatial directions ($t_x \ne t_y$ and $J_x \ne J_y$). Incommensurate peaks
+in the spin structure factor show up only in the presence of a lattice
+anisotropy, whereas charge correlations, indicating enhanced fluctuations at
+incommensurate wave vectors, are almost unaffected with respect to the
+isotropic case.",0108198v1
+2002-01-08,Field dependent anisotropy change in a supramolecular Mn(II)-[3x3] grid,"The magnetic anisotropy of a novel Mn(II)-[3x3] grid complex was investigated
+by means of high-field torque magnetometry. Torque vs. field curves at low
+temperatures demonstrate a ground state with S > 0 and exhibit a torque step
+due to a field induced level-crossing at B* \approx 7.5 T, accompanied by an
+abrupt change of magnetic anisotropy from easy-axis to hard-axis type. These
+observations are discussed in terms of a spin Hamiltonian formalism.",0201090v1
+2002-01-19,Vibrationally induced fourth-order magnetic anisotropy and tunnel splittings in Mn_{12},"From density-functional-theory (DFT) based methods we calculate the
+vibrational spectrum of the Mn_{12}O_{12}(COOH)_{16}(H_2 O)_4 molecular magnet.
+Calculated infrared intensities are in accord with experimental studies. There
+have been no ab initio attempts at determining which interactions account for
+the fourth-order anisotropy. We show that vibrationally induced distortions of
+the molecule contribute to the fourth-order anisotropy Hamiltonian and that the
+magnitude and sign of the effect (-6.2 K) is in good agreement with all
+experiments. Vibrationally induced tunnel splittings in isotopically pure and
+natural samples are predicted.",0201353v2
+2002-02-25,Spin Relaxation Anisotropy in Two-Dimensional Semiconductor Systems,"Spin relaxation is investigated theoretically in two-dimensional systems.
+Various semiconductor structures of both n- and p-types are studied in detail.
+The most important spin relaxation mechanisms are considered. The spin
+relaxation times are calculated taking into account the contributions to the
+spin--orbit interaction due to both the bulk inversion asymmetry and the
+structure inversion asymmetry. It is shown that in-plane anisotropy of electron
+spin relaxation appears in III--V asymmetrical heterostructures. This
+anisotropy may be controlled by external parameters, and the spin relaxation
+times differ by several orders of magnitude.",0202437v1
+2002-02-28,Anisotropy of ultra-thin ferromagnetic films and the spin reorientation transition,"The influence of uniaxial anisotropy and the dipole interaction on the
+direction of the magnetization of ultra-thin ferromagnetic films in the
+ground-state is studied. The ground-state energy can be expressed in terms of
+anisotropy constants which are calculated in detail as function of the system
+parameters and the film thickness. In particular non-collinear spin
+arrangements are taken into account. Conditions for the appearance of a spin
+reorientation transition are given and analytic results for the width of the
+canted phase and its shift in applied magnetic fields associated with this
+transition are derived.",0202534v1
+2002-03-27,Piezoresistive anisotropy of percolative granular metals,"The piezoresistive response of granular metals under uniaxial strain is
+strongly dependent on the concentration of the conducting phase. Here we show
+that the piezoresistive anisotropy is reduced as the system approaches its
+percolation thresold, following a power law behavior in the critical region. We
+propose a simple relation between the conductance and the piezoresistive
+anisotropy which could be used in relation to real materials and notably to the
+thick film resistors.",0203557v1
+2002-04-01,Macroscopic anisotropy in superconductors with anisotropic gaps,"It is shown within the weak-coupling model that the macroscopic
+superconducting anisotropy for materials with the gap varying on the Fermi
+surface cannot be characterized by a single number, unlike the case of clean
+materials with isotropic gaps. For clean uniaxial materials, the anisotropy
+parameter $\gamma (T)$ defined as the ratio of London penetration depths,
+$\lambda_c/\lambda_{ab}$, is evaluated for all $T$'s. Within the two-gap model
+of MgB$_2$, $\gamma (T)$ is an increasing function of $T$.",0204038v1
+2002-04-25,"Comment on ""Anisotropic s-wave superconductivity in MgB_2""","An analytical result for renormalization of the jump of the heat capacity
+Delta C/C_N by the anisotropy of the order parameter is derived in the
+framework of the model proposed by Haas and Maki [Phys. Rev. B 65, 020502(R)
+(2001)], for both prolate and oblate anisotropy. The graph of Delta C/C_N
+versus the ratio of the gaps on the equator and the pole, Delta_e/Delta_p, of
+the Fermi surface allows a direct determination of the gap anisotropy parameter
+Delta_e/Delta_p using data from specific heat measurements.",0204545v1
+2002-05-08,Superconductor-to-Spin-Density-Wave Transition in Quasi-One-Dimensional Metals with Ising Anisotropy,"We study a mechanism for superconductivity in quasi-one-dimensional materials
+with Ising anisotropy. In an isolated chain Ising anisotropy opens a spin gap;
+if inter-chain coupling is sufficiently weak, single particle hopping is
+suppressed and the physics of coupled chains is controlled by a competition
+between pair hopping and exchange interaction. Spin density wave and triplet
+superconductivity phases are found separated by a first order phase transition.
+For particular parameter values a second order transition described by SO(4)
+symmetry is found.",0205166v1
+2002-07-26,Coherence lengths and anisotropy in MgB2 superconductor,"Field and temperature microwave measurements have been carried out on MgB2
+thin film grown on Al2O3 substrate. The analysis reveals the mean field
+coherence length xi_{MF} in the mixed state and a temperature independent
+anisotropy ratio gamma_{MF} = xi_{MF}^{ab} / xi_{MF}^c approximately 2. At the
+superconducting transition, the scaling of the fluctuation conductivity yields
+the Ginzburg-Landau coherence length with a different anisotropy ratio
+gamma_{GL} = 2.8, also temperature independent.",0207655v1
+2002-07-29,Free energy and torque for superconductors with different anisotropies of H_{c2} and lambda,"The free energy is evaluated for a uniaxial superconductor with the
+anisotropy of the upper critical field, gamma_H = H_{c2,ab}/H_{c2,c}, different
+from the anisotropy of the penetration depth gamma_{lambda} =
+lambda_c/lambda_{ab}. With increasing difference between gamma_H and
+gamma_{lambda}, the equilibrium orientation of the crystal relative to the
+applied field may shift from theta = pi/2 (theta is the angle between the field
+and the c axis) to lower angles and reach theta = 0 for large enough gamma_H.
+These effects are expected to take place in MgB_2.",0207688v1
+2002-09-04,Correlation Effects on Magnetic Anisotropy in Fe and Ni,"We calculate magnetic anisotropy energy of Fe and Ni by taking into account
+the effects of strong electronic correlations, spin-orbit coupling, and
+non-collinearity of intra-atomic magnetization. The LDA+U method is used and
+its equivalence to dynamical mean-field theory in the static limit is derived.
+The effects of strong correlations are studied along several paths in $(U,J)$
+parameter space. Both experimental magnitude of MAE and direction of
+magnetization are predicted correctly near $U=1.9 eV$, $J=1.2 eV$ for Ni and
+$U=1.2 eV$, $J=0.8 eV$ for Fe. The modified one-electron spectra by strong
+correlations are emphasized in conjunction with magnetic anisotropy.",0209073v1
+2002-11-11,Possible Jahn-Teller effect in Si-inverse layers,"Jahn-Teller effect in bivalley Si(100) MOSFET under conditions of quantum
+Hall effect at integer filling factors nu=1,2,3 is studied. This system is
+described by SU(4) hidden symmetry. At nu=2 static and dynamic lattice
+deformation creates an easy-plane anisotropy and antiferromagnetic exchange and
+lifts the valley degeneracy. At nu=1,3 Coulomb interaction is essential to
+produce weak easy-plane anisotropy. Three phases: ferromagnetic, canted
+antiferromagnetic and spin-singlet, have been found. Anisotropy energy of
+charged skyrmion excitation in every phase is found.",0211214v1
+2002-12-13,Step bunching during Si(001) homoepitaxy caused by the surface diffusion anisotropy,"Scanning tunneling microscopy experiments show that the unstable growth
+morphology observed during molecular beam homoepitaxy on slightly vicinal
+Si(001) surfaces consists of straight step bunches. The instability occurs
+under step- flow growth conditions and vanishes both during low-temperature
+island growth and at high temperatures. An instability with the same
+characteristics is observed in a 2D Kinetic Monte Carlo model of growth with
+incorporated Si(001)- like diffusion anisotropy. This provides strong evidence
+that the diffusion anisotropy destabilizes growth on Si(001) and similar
+surfaces towards step bunching. This new instability mechanism is operational
+without any additional step edge barriers.",0212331v1
+2003-01-07,Anisotropy of the Mobility of Pentacene from Frustration,"The bandstructure of pentacene is calculated using first-principles density
+functional theory. A large anisotropy of the hole and electron effective masses
+within the molecular planes is found. The band dispersion of the HOMO and the
+LUMO is analyzed with the help of a tight-binding fit. The anisotropy is shown
+to be intimately related to the herringbone structure.",0301078v1
+2003-03-17,Anisotropic susceptibility of ferromagnetic ultrathin Co films on vicinal Cu,"We measure the magnetic susceptibility of ultrathin Co films with an in-plane
+uniaxial magnetic anisotropy grown on a vicinal Cu substrate. Above the Curie
+temperature the influence of the magnetic anisotropy can be investigated by
+means of the parallel and transverse susceptibilities along the easy and hard
+axes. By comparison with a theoretical analysis of the susceptibilities we
+determine the isotropic exchange interaction and the magnetic anisotropy. These
+calculations are performed in the framework of a Heisenberg model by means of a
+many-body Green's function method, since collective magnetic excitations are
+very important in two-dimensional magnets.",0303320v1
+2003-04-15,Shape and surface anisotropy effects on the hysteresis of ferrimagnetic nanoparticles,"We present the results of Monte Carlo simulations of a model of a single
+maghemite ferrimagnetic nanoparticle with the aim to clarify the role played by
+the increased anisotropy at the surface and by the shape (spherical or
+elliptical) of the particle on the magnetization processes at low temperatures.
+The formation of hedgehog-like structures for high enough surface anisotropy is
+responsible for a change in the reversal mechanism of the particles.",0304330v1
+2003-05-08,Current percolation and anisotropy in polycrystalline MgB$_2$,"The influence of anisotropy on the transport current in MgB$_2$
+polycrystalline bulk samples and wires is discussed. A model for the critical
+current density is proposed, which is based on anisotropic London theory, grain
+boundary pinning and percolation theory. The calculated currents agree
+convincingly with experimental data and the fit parameters, especially the
+anisotropy, obtained from percolation theory agree with experiment or
+theoretical predictions.",0305168v1
+2003-07-11,Quantum phase transition in easy-axis antiferromagnetic integer-spin chains,"Antiferromagnetic Heisenberg integer-spin chains are characterized by a
+spin-liquid ground state with no long-range order, due to the relevance of
+quantum fluctuations. Spin anisotropy, however, freezes quantum fluctuations,
+and the system is magnetized in the presence of a sufficiently large easy-axis
+anisotropy. We numerically investigate the case S=1, by means of the
+density-matrix renormalization group, and find that the freezing of the spin
+liquid into a N\'eel spin solid, with increasing easy-axis anisotropy, is a
+continuous quantum phase transition. Numerical evidence indicates that the
+transition is not in the two-dimensional Ising universality class.",0307266v1
+2003-07-17,"Anisotropy and universality: the Oslo model, the rice pile experiment and the quenched Edwards-Wilkinson equation","We show that any amount of anisotropy moves the Oslo model to another known
+universality class, the exponents of which can be derived exactly. This amounts
+to an exact solution of the quenched Edwards-Wilkinson equation with a drift
+term. We argue that anisotropy is likely to be experimentally relevant and may
+explain why consistent exponents have not been extracted in the rice pile
+experiments.",0307443v1
+2003-07-27,Anisotropy of the incommensurate fluctuations in Sr2RuO4: a study with polarized neutrons,"The anisotropy of the magnetic incommensurate fluctuations in Sr2RuO4 has
+been studied by inelastic neutron scattering with polarized neutrons. We find a
+sizeable enhancement of the out of plane component by a factor of two for
+intermediate energy transfer which appears to decrease for higher energies. Our
+results qualitatively confirm calculations of the spin-orbit coupling, but the
+experimental anisotropy and its energy dependence are weaker than predicted.",0307662v1
+2003-08-14,Anisotropy and percolation threshold in a multifractal support,"Recently a multifractal object, $Q_{mf}$, was proposed to study percolation
+properties in a multifractal support. The area and the number of neighbors of
+the blocks of $Q_{mf}$ show a non-trivial behavior. The value of the
+probability of occupation at the percolation threshold, $p_{c}$, is a function
+of $\rho$, a parameter of $Q_{mf}$ which is related to its anisotropy. We
+investigate the relation between $p_{c}$ and the average number of neighbors of
+the blocks as well as the anisotropy of $Q_{mf}$.",0308291v1
+2003-10-08,Magnetic Anisotropy of SrCu$_2$(BO$_3$)$_2$ System as Revealed by X-Band ESR,"X-band ESR measurements on a single crystal of the highly frustrated
+SrCu$_2$(BO$_3$)$_2$ system are shown to provide an essential inspection of the
+magnetic anisotropy present in this compound. The very broad absorption lines
+seem to be consistent with the largest anisotropy term, namely, the
+antisymmetric Dzyaloshinsky-Moriya (DM) interaction allowed by symmetry.
+However, the previously well-accepted model of only interdimer interaction is
+generalized with additional intradimer DM terms. Moreover, spin-phonon coupling
+is recognized as the cause on the linewidth broadening with increasing
+temperature.",0310178v1
+2004-04-07,Temperature Anisotropy in a Driven Granular Gas,"When smooth granular material is fluidized by vertically shaking a container,
+we find that the temperature in the direction of energy input always exceeds
+the temperature in the other directions. An analytical model is presented which
+shows how the anisotropy can be traced back to the inelasticity of the
+interparticle collisions and the collisions with the wall. The model compares
+very well with molecular dynamics simulations. It is concluded that any
+non-isotropic driving of a granular gas in a steady state necessarily causes
+anisotropy of the granular temperature.",0404174v2
+2004-08-04,Quasiparticle dynamics and in-plane anisotropy in $Y Ba_2 Cu_3 O_y$ system near onset of superconductivity,"We report on an infrared study of carrier dynamics within the CuO$_{2}$
+planes in heavily underdoped detwinned single crystals of YBa$_{2}$Cu$_{3}$O$%
+_{y}$. In an effort to reveal the electronic structure near the onset of
+superconductivity, we investigate the strong anisotropy of the electromagnetic
+response due to an enhancement of the scattering rate along the a-axis. We
+propose that the origin of this anisotropy is related to a modulation of the
+electron density within the CuO$_{2}$ planes.",0408097v1
+2004-10-01,"Mixed magnetic phases in (Ga,Mn)As epilayers","Two different ferromagnetic-paramagnetic transitions are detected in
+(Ga,Mn)As/GaAs(001) epilayers from ac susceptibility measurements: transition
+at a higher temperature results from (Ga,Mn)As cluster phases with [110]
+uniaxial anisotropy and that at a lower temperature is associated with a
+ferromagnetic (Ga,Mn)As matrix with <100> cubic anisotropy. A change in the
+magnetic easy axis from [100] to [110] with increasing temperature can be
+explained by the reduced contribution of <100> cubic anisotropy to the magnetic
+properties above the transition temperature of the (Ga,Mn)As matrix.",0410022v1
+2004-11-18,Giant optical anisotropy in a single InAs quantum dot in a very dilute quantum-dot ensemble,"We present the experimental evidence of giant optical anisotropy in single
+InAs quantum dots. Polarization-resolved photoluminescence spectroscopy reveals
+a linear polarization ratio with huge fluctuations, from one quantum dot to
+another, in sign and in magnitude with absolute values up to 82%. Systematic
+measurements on hundreds of quantum dots coming from two different laboratories
+demonstrate that the giant optical anisotropy is an intrinsic feature of dilute
+quantum-dot arrays.",0411484v1
+2004-12-02,One-Dimensional S=1 Spin-Orbital Model with Uniaxial Single-Ion Anisotropy,"We investigate ground-state properties of a one-dimensional S=1 spin-orbital
+model with or without uniaxial single-ion anisotropy. By means of the density
+matrix renormalization group method, we compute the ground-state energy, the
+magnetization curves and the correlation functions. We discuss how the
+ground-state properties depend on the two exchange couplings for orbital and
+spin sectors. The phase diagram obtained is compared with that for the S=1/2
+model. We also address the effect of uniaxial single-ion anisotropy.",0412067v1
+2005-02-08,Pressure and isotope effect on the anisotropy of MgB$_{2}$,"We analyze the data for the pressure and boron isotope effect on the
+temperature dependence of the magnetization near $T_{c}$. Invoking the
+universal scaling relation for the magnetization at fixed magnetic field it is
+shown that the relative shift of $T_{c}$, induced by pressure or boron isotope
+exchange, mirrors essentially that of the anisotropy. This uncovers a novel
+generic property of anisotropic type II superconductors, inexistent in the
+isotropic case. For MgB$_{2}$ it implies that the renormalization of the Fermi
+surface topology due to pressure or isotope exchange is dominated by a
+mechanism controlling the anisotropy.",0502202v1
+2005-04-11,Lattice pinning of magnetic domains in the helimagnet Ba_2CuGe_2O_7,"The layered magnetic compound Ba_2CuGe_2O_7 exhibits spiral antiferromagnetic
+order thanks to a Dzyaloshinskii-Moriya (DM) anisotropy that is allowed by
+crystal symmetry. Here we theoretically examine some finer issues such as the
+experimentally observed lattice pinning of the propagation vector of helical
+magnetic domains. We find that DM anisotropy alone would lead to incorrect
+pinning, but agreement with experiment is restored upon including an additional
+exchange anisotropy that is also consistent with symmetry. The present results
+shed light on the so-called bisection rule which has been abstracted from
+experiment in presence of an in-plane magnetic field.",0504262v1
+2005-04-19,Spin-glass behavior in the random-anisotropy Heisenberg model,"We perform Monte Carlo simulations in a random anisotropy magnet at a
+intermediate exchange to anisotropy ratio. We focus on the out of equilibrium
+relaxation after a sudden quenching in the low temperature phase, well below
+the freezing one. By analyzing both the aging dynamics and the violation of the
+Fluctuation Dissipation relation we found strong evidence of a spin--glass like
+behavior. In fact, our results are qualitatively similar to those
+experimentally obtained recently in a Heisenberg-like real spin glass.",0504483v2
+2005-07-07,Magnetic plateaus in the 1D antiferromagnetic spin-3/2 and spin-2 Ising chains with single-ion anisotropy,"In this study, we have employed the classical transfer matrix technique to
+investigate the magnetization plateaus, phase diagrams and other
+thermodynamical properties of the one-dimensional antiferromagnetic spin-3/2
+and spin-2 Ising chains with single-ion anisotropy in the presence of an
+external magnetic field at very low temperature. We have showed that single
+ion-anisotropy is one of the indispensable ingredients for an energy gap which
+leads to magnetic plateau mechanism in one-dimensional antiferromagnetic Ising
+spin chains. Other thermodynamical predictions seem to be provide this
+argument.",0507177v1
+2005-07-07,"Reorientation Transition in Single-Domain (Ga,Mn)As","We demonstrate that the interplay of in-plane biaxial and uniaxial anisotropy
+fields in (Ga,Mn)As results in a magnetization reorientation transition and an
+anisotropic AC susceptibility which is fully consistent with a simple single
+domain model. The uniaxial and biaxial anisotropy constants vary respectively
+as the square and fourth power of the spontaneous magnetization across the
+whole temperature range up to T_C. The weakening of the anisotropy at the
+transition may be of technological importance for applications involving
+thermally-assisted magnetization switching.",0507187v1
+2005-08-01,Investigation of the anisotropy of dissipation processes in single crystal of Yba2Cu3O7-d system,"By means of contactless mechanical method of the measurement of energy losses
+in superconductors, the anisotropy of dissipation processes has been studied in
+single crystal high-temperature layered superconductors of Yba2Cu3O7-d system,
+being in mixed state. The observed anisotropy of energy losses indicates the
+possibility of the existence of the symmetry of order parameter of dx2-y2 type
+in these single crystals.",0508050v1
+2005-11-11,Pairing States of Superfluid 3He in Uniaxially Anisotropic Aerogel,"Stable pairing states of superfluid 3He in aerogel are examined in the case
+with a global uniaxial anisotropy which may be created by applying an uniaxial
+stress to the aerogel. Due to such a global anisotropy, the stability region of
+an ABM pairing state becomes wider. In an uniaxially stretched aerogel, the
+pure polar pairing state with a horizontal line node is predicted to occur, as
+a 3d superfluid phase, over a measurable width just below the superfluid
+transition at T_c(P). A possible relevance of the present results to the case
+with no global anisotropy is also discussed.",0511280v2
+2005-12-06,Hc2 of anisotropy two-band superconductors by Ginzburg-Landau approach,"The purpose of this research is to study the upper critical field (Hc2) of
+two-band superconductors by two-band Ginzburg - Landau approach. The analytical
+formula of Hc2 included anisotropy of order parameter and anisotropy of
+effective-mass are found . The parameters of the upper critical field in
+ab-plane and c-axis can be found by fitting to the experimental data . Finally,
+we can find the ratio of upper critical field that temperature dependent in the
+range of experimental result .",0512105v1
+2006-01-19,A significant influence of the substrate on the magnetic anisotropy of monatomic nanowires,"The magnetic anisotropy energy of Fe and Co monatomic nanowires both
+free-standing and at the step edge of a Pt surface is investigated within the
+framework of the density-functional theory and local-spin-density (LSDA)
+approximation. Various types of the analysis of the calculated data reveal that
+the spin-orbit interaction of the Pt atoms and the hybridization between the
+electronic states have an important impact on the direction of the easy axis
+and on the magnitude of the magnetic anisotropy, both by a direct contribution
+localized at the Pt atoms and by an indirect contribution due to the
+modification of the Co-localized part via hybridization effects.",0601445v1
+2006-02-07,Angular dependence of the magnetic-field driven superconductor-insulator transition in thin films of amorphous indium-oxide,"A significant anisotropy of the magnetic-field driven
+superconductor-insulator transition is observed in thin films of amorphous
+indium-oxide. The anisotropy is largest for more disordered films which have a
+lower transition field. At higher magnetic field the anisotropy reduces and
+even changes sign beyond a sample specific and temperature independent magnetic
+field value. The data are consistent with the existence of more that one
+mechanism affecting transport at high magnetic fields.",0602160v1
+2006-05-03,Anisotropic Elastic Model for Short DNA Loops,"Effect of bending anisotropy on a planar DNA loop, using energy minimization
+and neglecting entropic effects, is studied. We show that the anisotropy
+results in polygonal shape of the loop and increasing the anisotropy makes the
+edges sharper. Calculating the energy of such a loop lets us to find effective
+persistence length as the geometrical mean of hard and soft rigidities, which
+is quite different from harmonic mean for an unconstrained long DNA.",0605086v2
+2006-10-31,Magnetic anisotropies of late transition metal atomic clusters,"We analyze the impact of the magnetic anisotropy on the geometric structure
+and magnetic ordering of small atomic clusters of palladium, iridium, platinum
+and gold, using Density Functional Theory. Our results highlight the absolute
+need to include self-consistently the spin orbit interaction in any simulation
+of the magnetic properties of small atomic clusters, and a complete lack of
+universality in the magnetic anisotropy of small-sized atomic clusters.",0610879v2
+2000-05-09,Cosmic microwave background anisotropies seeded by incoherent sources,"The cosmic microwave background anisotropies produced by active seeds, such
+as topological defects, have been computed recently for a variety of models by
+a number of authors. In this paper we show how the generic features of the
+anisotropies caused by active, incoherent, seeds (that is the absence of
+acoustic peaks at small scales) can be obtained semi-analytically, without
+entering into the model dependent details of their formation, structure and
+evolution.",0005024v1
+2001-10-19,Anisotropic Lattices and Dynamical Fermions,"We report results from full QCD calculations with two flavors of dynamical
+staggered fermions on anisotropic lattices. The physical anisotropy as
+determined from spatial and temporal masses, their corresponding dispersion
+relations, and spatial and temporal Wilson loops is studied as a function of
+the bare gauge anisotropy and the bare velocity of light appearing in the Dirac
+operator. The anisotropy dependence of staggered fermion flavor symmetry
+breaking is also examined. These results will then be applied to the study of
+2-flavor QCD thermodynamics.",0110171v1
+1998-02-20,Galactic Anisotropy as Signature of ``Top-Down'' Mechanisms of Ultra-High Energy Cosmic Rays,"We show that ``top-down'' mechanisms of Ultra-High Energy Cosmic Rays which
+involve heavy relic particle-like objects predict Galactic anisotropy of
+highest energy cosmic rays at the level of minimum $\sim 20%$. This anisotropy
+is large enough to be either observed or ruled out in the next generation of
+experiments.",9802382v2
+1998-10-19,Galactic anisotropy of Ultra-High Energy Cosmic Rays produced by CDM-related mechanisms,"We briefly review current theoretical and experimental status of Ultra-High
+Energy Cosmic Rays. We show that ``top-down'' mechanisms of UHE CR which
+involve heavy relic particle-like objects predict Galactic anisotropy of
+highest energy cosmic rays at the level of minimum $\sim 20%$. This anisotropy
+is large enough to be either observed or ruled out in the next generation of
+experiments.",9810401v1
+2000-02-24,Anisotropy of Dynamical Fluctuations as a Probe for Soft and Hard Processes in High Energy Collisions,"It is shown using Lund Monte Carlo that, unlike the average properties of the
+hadronic system inside jets, the anisotropy of dynamical fluctuations in these
+systems changes abruptly with the variation of the cut parameter $y_cut$. A
+transition point exists, where the dynamical fluctuations in the hadronic
+system inside jet behave like those in soft hadronic collisions. Thus the
+anisotropy property of the dynamical fluctuations can serve as a probe for the
+soft and hard processes in high energy collisions.",0002244v2
+2001-02-13,Pressure and intermittency in passive vector turbulence,"We investigate the scaling properties a model of passive vector turbulence
+with pressure and in the presence of a large-scale anisotropy. The leading
+scaling exponents of the structure functions are proven to be anomalous. The
+anisotropic exponents are organized in hierarchical families growing without
+bound with the degree of anisotropy. Nonlocality produces poles in the
+inertial-range dynamics corresponding to the dimensional scaling solution. The
+increase with the P\'{e}clet number of hyperskewness and higher odd-dimensional
+ratios signals the persistence of anisotropy effects also in the inertial
+range.",0102017v1
+2001-05-01,Rectangular microwave resonators with magnetic anisotropy. Mapping onto pseudo integrable rhombus,"The rectangular microwave resonator filed by a ferrite with uniaxial magnetic
+anisotropy is considered. It is shown that this task can be reduced to an empty
+rhombus resonator with vertex angle defined by external magnetic field provided
+the magnetic anisotropy of the ferrite is strong. Therefore statistics of eigen
+frequencies for TM modes is described by the Brody or semi-Poisson distribution
+with some exceptional cases.",0105001v1
+2005-06-16,Scaling properties of azimuthal anisotropy of mesons and baryons at RHIC,"Detailed measurements of the azimuthal anisotropy (\v2) for identified
+charged particles are reported as a function of transverse momentum ($p_T$) and
+centrality for Au+Au collisions at \sqrtsNN = 200 GeV. The measurements
+indicate clear evidence for eccentricity and particle flavor scaling over a
+broad range of centralities and transverse rapidity $y_T$, indicating a
+hydrodynamical origin of the fine structure of azimuthal anisotropy at RHIC.
+The observed scaling supports the picture of a suddenly hadronizing
+(recombining) fluid of quarks. An apparent breaking of flavor scaling at
+relatively large values of $y_T$ points to an important change in the mechanism
+for particle emission.",0506019v1
+2005-10-08,The azimuthal anisotropy of electrons from heavy flavor decays in sqrt(s_NN) = 200 GeV Au-Au collisions by PHENIX,"The transverse momentum dependence of the azimuthal anisotropy parameter
+v_{2}, the second harmonic of the azimuthal distribution, for electrons at
+mid-rapidity (|eta|<0.35) has been measured with the PHENIX detector in Au+Au
+collisions at sqrt(s_NN) = 200 GeV with respect to the reaction plane defined
+at high rapidities (|eta|=3-4). From the result we have calculated non-photonic
+electron v_{2}, which is expected to reflect the heavy-flavor azimuthal
+anisotropy, by subtracting v_{2} of electrons from other sources such as photon
+conversions, Dalitz decay etc.",0510027v1
+2006-07-18,Centrality Dependence of Azimuthal Anisotropy of Strange Hadrons in 200 GeV Au+Au Collisions,"Measurements of azimuthal anisotropy for strange and multi-strange hadrons
+are presented for the first time in their centrality dependence. The high
+statistics results of v2(pT) allow for a more detailed comparison to
+hydrodynamical model calculations. Number-of-constituent-quark scaling was
+tested for different centrality classes separately. Higher order anisotropies
+like v4(pT) are measured for multi-strange hadrons. While we observe agreement
+between measured data and models a deeper understanding and refinement of the
+models seem to be necessary in order to fully understand the details of the
+data.",0607021v1
+2001-04-05,Is there elliptic flow without transverse flow?,"Azimuthal anisotropy of final particle distributions was originally
+introduced as a signature of transverse collective flow. We show that finite
+anisotropy in momentum space can result solely from the shape of the particle
+emitting source. However, by comparing the differential anisotropy to recent
+data from STAR collaboration we can exclude such a scenario, but instead show
+that the data favour strong flow as resulting from a hydrodynamical evolution.",0104020v1
+2005-09-30,Azimthally sensitive femtoscopy and v2,"I investigate the correlation between spatial and flow anisotropy in
+determining the elliptic flow and azimuthal dependence of the HBT correlation
+radii in non-central nuclear collisions. It is shown that the correlation radii
+are in most cases dominantly sensitive to the anisotropy in space. In case of
+v2, the correlation depends strongly on particle species. A procedure for
+disentangling the spatial and the flow anisotropy is proposed.",0509100v1
+2006-03-13,Finite driving rate and anisotropy effects in landslide modeling,"In order to characterize landslide frequency-size distributions and
+individuate hazard scenarios and their possible precursors, we investigate a
+cellular automaton where the effects of a finite driving rate and the
+anisotropy are taken into account. The model is able to reproduce observed
+features of landslide events, such as power-law distributions, as
+experimentally reported. We analyze the key role of the driving rate and show
+that, as it is increased, a crossover from power-law to non power-law behaviors
+occurs. Finally, a systematic investigation of the model on varying its
+anisotropy factors is performed and the full diagram of its dynamical behaviors
+is presented.",0603100v1
+2006-07-13,Persistence of small-scale anisotropy of magnetic turbulence as observed in the solar wind,"The anisotropy of magnetophydrodynamic turbulence is investigated by using
+solar wind data from the Helios 2 spacecraft. We investigate the behaviour of
+the complete high-order moment tensors of magnetic field increments and we
+compare the usual longitudinal structure functions which have both isotropic
+and anisotropic contributions, to the fully anisotropic contribution. Scaling
+exponents have been extracted by an interpolation scaling function. Unlike the
+usual turbulence in fluid flows, small-scale magnetic fluctuations remain
+anisotropic. We discuss the radial dependence of both anisotropy and
+intermittency and their relationship.",0607128v1
+2007-05-01,Non-abelian plasma instabilities for strong anisotropy,"We numerically investigate gauge field instabilities in anisotropic SU(2)
+plasmas using weak field initial conditions. The growth of unstable modes is
+stopped by non-abelian effects for moderate anisotropy. If we increase the
+anisotropy the growth continues beyond the non-abelian saturation bound. We
+find strong indications that the continued growth is not due to over-saturation
+of infrared field modes, but instead due to very rapid growth of high momentum
+modes which are not unstable in the weak field limit. The saturation amplitude
+strongly depends on the initial conditions. For strong initial fields we do not
+observe the sustained growth.",0705.0180v1
+2007-06-18,Search for large-scale anisotropies with the Auger Observatory,"We use more than two years of data from the Pierre Auger Observatory to
+search for anisotropies on large scales in different energy windows. We account
+for various systematics in the acceptance, in particular due to the array
+growth and weather variations. We present the results of analyses and
+consistency checks looking for patterns in the right ascension modulation of
+the cosmic ray distribution. No significant anisotropies of this kind are
+observed.",0706.2640v1
+2007-07-13,Multiphoton antiresonance in large-spin systems,"We study nonlinear response of a spin $S>1/2$ with easy-axis anisotropy. The
+response displays sharp dips or peaks when the modulation frequency is
+adiabatically swept through multiphoton resonance. The effect is a consequence
+of a special symmetry of the spin dynamics in a magnetic field for the
+anisotropy energy $\propto S_z^2$. The occurrence of the dips or peaks is
+determined by the spin state. Their shape strongly depends on the modulation
+amplitude. Higher-order anisotropy breaks the symmetry, leading to sharp steps
+in the response as function of frequency. The results bear on the dynamics of
+molecular magnets in a static magnetic field.",0707.2107v1
+2008-01-09,Anisotropy in the magnetic and electrical transport properties of Fe1-xCrxSb2,"We have investigated anisotropy in magnetic and electrical transport
+properties of Fe1-xCrxSb2 (0<= x <=1) single crystals. The magnetic ground
+state of the system evolves from paramagnetic to antiferromagnetic with gradual
+substitution of Fe with Cr. Anisotropy in electrical transport diminishes with
+increased Cr substitution and fades away by x=0.5. We find that the variable
+range hopping (VRH) conduction mechanism dominates at low temperatures for
+0.4<= x <=0.75.",0801.1351v2
+2008-03-02,Dewetting of an ultrathin solid film on a lattice-matched or amorphous substrate,"An evolution partial differential equation for the surface of a non-wetting
+single-crystal film in an attractive substrate potential is derived and used to
+study the dynamics of a pinhole for the varying initial depth of a pinhole and
+the strengths of the potential and the surface energy anisotropy. The results
+of the simulations demonstrate how the corresponding parameters may lead to
+complete or partial dewetting of the film. Anisotropy of the surface energy,
+through faceting of the pinhole walls, is found to most drastically affect the
+time to film rupture. In particular, the similations support the conjecture
+that the strong anisotropy is capable of the complete suppression of dewetting
+even when the attractive substrate potential is strong.",0803.0126v1
+2008-03-11,Metastable anisotropy orientation of nematic quantum Hall fluids,"We analyze the experimental observation of metastable anisotropy resistance
+orientation at half filled quantum Hall fluids by means of a model of a quantum
+nematic liquid in an explicit symmetry breaking potential. We interpret the
+observed ``rotation'' of the anisotropy axis as a process of nucleation of
+nematic domains and compute the nucleation rate within this model. By comparing
+with experiment, we are able to predict the critical radius of nematic bubbles,
+$R_c\sim 2.6 \mu m $. Each domain contains about $10^4$ electrons.",0803.1578v2
+2008-04-09,Electric field control of spin-orbit splittings in GaAs/AlGaAs coupled quantum wells,"Electron spin dynamics is investigated in n-i-n GaAs/AlGaAs coupled quantum
+wells. The electron spin dephasing time is measured as a function of an
+external electrical bias under resonant excitation of the 1sHH intrawell
+exciton using a time-resolved Kerr rotation technique. It is found a strong
+electron spin dephasing time anisotropy caused by an interference of the
+structure inversion asymmetry and the bulk inversion asymmetry. This anisotropy
+is shown to be controlled by an electrical bias. A theoretical analysis of
+electron spin dephasing time anisotropy is developed. The ratio of Rashba and
+Dresselhaus spin splittings is studied as a function of applied bias.",0804.1483v1
+2008-04-24,Current-induced domain wall motion in a nanowire with perpendicular magnetic anisotropy,"We study theoretically the current-induced magnetic domain wall motion in a
+metallic nanowire with perpendicular magnetic anisotropy. The anisotropy can
+reduce the critical current density of the domain wall motion. We explain the
+reduction mechanism and identify the maximal reduction conditions. This result
+facilitates both fundamental studies and device applications of the current-
+induced domain wall motion.",0804.3864v1
+2008-08-26,Magnetic anisotropy and reversal in epitaxial Fe/MgO(001) films revisited,"We investigate the magnetization reversal in Fe/MgO(001) films with fourfold
+in-plane magnetic anisotropy and an additional uniaxial anisotropy whose
+orientation and strength are tuned using different growth geometries and post
+growth treatments. The previously adopted mechanism of 180^{o} domain wall
+nucleation clearly fails to explain the observed 180^{o} magnetization
+reversal. A new reversal mechanism with two successive domain wall nucleations
+consistently predicts the switching fields for all field orientations. Our
+results are relevant for a correct interpretation of magnetization reversal in
+many other epitaxial metallic and semiconducting thin films.",0808.3543v2
+2008-08-29,The anisotropy of two dimensional percolation clusters of self-affine models,"The anisotropy parameter of two-dimensional equilibrium clusters of site
+percolation process in long-range self-affine correlated structures are studied
+numerically. We use a fractional Brownian Motion(FBM) statistic to produce both
+persistent and anti-persistent long-range correlations in 2-D models. It is
+seen that self affinity makes the shape of percolation clusters slightly more
+isotropic. Moreover, we find that the sign of correction to scaling term is
+determined by the nature of correlation. For persistent correlation the
+correction to scaling term adds a negative contribution to the anisotropy of
+percolation clusters, while for the anti-persistent case it is positive.",0808.4033v1
+2008-09-05,Interplay between one-dimensional confinement and crystallographic anisotropy in ballistic hole quantum wires,"We study the Zeeman splitting in induced ballistic 1D quantum wires aligned
+along the [233] and [011] axes of a high mobility (311)A undoped
+heterostructure. Our data shows that the g-factor anisotropy for magnetic
+fields applied along the high symmetry [011] direction can be explained by the
+1D confinement only. However when the magnetic field is along [233] there is an
+interplay between the 1D confinement and 2D crystal anisotropy. This is
+highlighted for the [233] wire by an unusual non-monotonic behavior of the
+g-factor as the wire is made narrower.",0809.0969v1
+2008-10-08,Mixed spin-1/2 and spin-1 Ising model with uniaxial and biaxial single-ion anisotropy on Bethe lattice,"The mixed spin-1/2 and spin-1 Ising model on the Bethe lattice with both
+uniaxial as well as biaxial single-ion anisotropy terms is exactly solved by
+combining star-triangle and triangle-star mapping transformations with exact
+recursion relations. Magnetic properties (magnetization, phase diagrams and
+compensation phenomenon) are investigated in detail. The particular attention
+is focused on the effect of uniaxial and biaxial single-ion anisotropies that
+basically influence the magnetic behavior of the spin-1 atoms.",0810.1371v2
+2008-10-11,Polarization singularity anisotropy: determining monstardom,"C points, that is isolated points of circular polarization in transverse
+fields of varying polarization, are classified morphologically into three
+distinct types, known as lemons, stars and monstars. These morphologies are
+interpreted here according to two natural parameters associated with the
+singularity, namely the anisotropy of the C point, and the polarization azimuth
+on the anisotropy axis. In addition to providing insight into singularity
+morphology, this observation applies to the densities of the various
+morphologies in isotropic random polarization speckle fields.",0810.2002v1
+2008-11-20,Effect of Bending Anisotropy on the 3D Conformation of Short DNA Loops,"The equilibrium three dimensional shape of relatively short loops of DNA is
+studied using an elastic model that takes into account anisotropy in bending
+rigidities. Using a reasonable estimate for the anisotropy, it is found that
+cyclized DNA with lengths that are not integer multiples of the pitch take on
+nontrivial shapes that involve bending out of planes and formation of kinks.
+The effect of sequence inhomogeneity on the shape of DNA is addressed, and
+shown to enhance the geometrical features. These findings could shed some light
+on the role of DNA conformation in protein--DNA interactions.",0811.3315v1
+2009-02-13,Exposing the Noncollectivity in Elliptic Flow,"We show that backward-forward elliptic anisotropy correlation provides an
+experimentally accessible observable which distinguishes between collective and
+non-collective contributions to the observed elliptic anisotropy $v_2$ in
+relativistic heavy ion collisions. The measurement of this observable will
+reveal the momentum scale at which collective expansion seizes and where the
+elliptic anisotropy is dominated by (semi)-hard processes.",0902.2377v2
+2009-03-28,An asymptotic preserving scheme for strongly anisotropic elliptic problems,"In this article we introduce an asymptotic preserving scheme designed to
+compute the solution of a two dimensional elliptic equation presenting large
+anisotropies. We focus on an anisotropy aligned with one direction, the
+dominant part of the elliptic operator being supplemented with Neumann boundary
+conditions. A new scheme is introduced which allows an accurate resolution of
+this elliptic equation for an arbitrary anisotropy ratio.",0903.4984v2
+2009-06-06,Stable two-dimensional ferromagnets made of regular single-layered lattices of single-molecule nanomagnets on substrates,"We propose that stable two-dimensional (2D) ferromagnets can be made of
+regular single-layered lattices of single-molecule nanomagnets with enough
+uniaxial magnetic anisotropy on appropriate substrates by controlling the
+inter-nanomagnet magnetic interaction. Our Monte Carlo simulated results show
+that such ideal 2D ferromagnets are thermodynamically stable when the
+anisotropy is strong enough. If the anisotropy energy equals 80 K,
+approximately that of the Mn12, the T_c varies from zero to 15 K depending on
+different inter-nanomagnet coupling constants. Such stable spin systems,
+experimentally accessible, should be promising for information applications.",0906.1298v1
+2009-06-06,Memory and aging effects in interacting sub-10nm nanomagnets with large uniaxial anisotropy,"Using a nonequilibrium Monte Carlo method suitable to nanomagnetism, we
+investigate representative systems of interacting sub-10nm grained nanomagnets
+with large uniaxial anisotropy. Various magnetization memory and aging effects
+are found in such systems. We explain these dynamical effects using the
+distributed relaxation times of the interacting nanomagnets due to their large
+anisotropy energies.",0906.1300v1
+2009-07-07,"Tunneling Anisotropic Spin Polarization in lateral (Ga,Mn)As/GaAs spin Esaki diode devices","We report here on anisotropy of spin polarization obtained in lateral
+all-semiconductor all-electrical spin injection devices, employing
+$p^{+}-$(Ga,Mn)As/$n^{+}-$GaAs Esaki diode structures as spin aligning
+contacts, resulting from the dependence of the efficiency of spin tunneling on
+the orientation of spins with respect to different crystallographic directions.
+We observed an in-plane anisotropy of $~8%$ in case of spins oriented either
+along $[1\bar{1}0]$ or $[110]$ directions and $~25%$ anisotropy between
+in-plane and perpendicular-to-plane orientation of spins.",0907.1202v1
+2009-07-23,Quantum Heisenberg antiferromagnetic chains with exchange and single--ion anisotropies,"Using density matrix renormalization group calculations, ground state
+properties of the spin-1 Heisenberg chain with exchange and quadratic
+single-ion anisotropies in an external field are studied, for special choices
+of the two kinds of anisotropies. In particular, the phase diagram includes
+antiferromagnetic, spin-liquid (or spin-flop), (10), and supersolid (or
+biconical) phases. Especially, new features of the spin-liquid and supersolid
+phases are discussed. Properties of the quantum chains are compared to those of
+corresponding classical spin chains.",0907.4168v1
+2009-08-10,Phase diagram of an anisotropic frustrated ferromagnetic spin-1/2 chain in a magnetic field: a density matrix renormalization group study,"We study the phase diagram of a frustrated spin-1/2 ferromagnetic chain with
+anisotropic exchange interactions in an external magnetic field, using the
+density matrix renormalization group method. We show that an easy-axis
+anisotropy enhances the tendency towards multimagnon bound states, while an
+easy-plane anisotropy favors chirally ordered phases. In particular, a moderate
+easy-plane anisotropy gives rise to a quantum phase transition at intermediate
+magnetization. We argue that this transition is related to the finite-field
+phase transition experimentally observed in the spin-1/2 compound LiCuVO_4.",0908.1281v2
+2009-08-12,On quarkonium in an anisotropic quark gluon plasma,"We reconsider a plasma with an anisotropy imposed on the momentum
+distribution of the system and study the real time static potential for
+quarkonia. The distribution function is normalised so as to preserve the
+particle number in an ideal gas, as required in the Keldysh-Schwinger
+formalism. In contrast to recent findings without this normalisation, a weak
+anisotropy does not lead to an increase in the melting temperature for bound
+states. To test for the maximal effect, we also investigate a gluonic medium in
+the limit of an asymptotically strong anisotropy. The spectral function of
+quarkonium is calculated for this case and found to be in remarkable agreement
+with the corresponding results for an isotropic medium.",0908.1746v1
+2009-09-25,Nernst effect anisotropy as a sensitive probe of Fermi surface distortions from electron-nematic order,"We analyze the thermoelectric response in layered metals with spontaneously
+broken rotation symmetry. We identify the anisotropy of the quasiparticle
+Nernst signal as an extremely sensitive probe of Fermi surface distortions
+characteristic of the ordered state. This is due to a subtle interplay of
+different transport anisotropies which become additionally enhanced near
+van-Hove singularities. Applied to recent experiments, our results reinforce
+the proposal that the underdoped cuprate superconductor YBCO displays such
+``electron-nematic'' order in the pseudogap regime.",0909.4534v2
+2009-10-17,Intrinsic anisotropy of thermal conductance in graphene nanoribbons,"Thermal conductance of graphene nanoribbons (GNRs) with the width varying
+from 0.5 to 35 nm is systematically investigated using nonequilibrium Green's
+function method. Anisotropic thermal conductance is observed with the room
+temperature thermal conductance of zigzag GNRs up to ~ 30% larger than that of
+armchair GNRs. At room temperature, the anisotropy is found to disappear until
+the width is larger than 100 nm. This intrinsic anisotropy originate from
+different boundary condition at ribbon edges, and can be used to tune thermal
+conductance, which have important implications for the applications of GNRs in
+nanoelectronics and thermoelectricity.",0910.3267v1
+2009-10-22,Theory of exciton fine structure in semiconductor quantum dots: quantum dot anisotropy and lateral electric field,"Theory of exciton fine structure in semiconductor quantum dots and its
+dependence on quantum dot anisotropy and external lateral electric field is
+presented. The effective exciton Hamiltonian including long range electron-hole
+exchange interaction is derived within the k*p effective mass approximation
+(EMA). The exchange matrix elements of the Hamiltonian are expressed explicitly
+in terms of electron and hole envelope functions. The matrix element
+responsible for the ""bright"" exciton splitting is identified and analyzed. An
+excitonic fine structure for a model quantum dot with quasi- two-dimensional
+anisotropic harmonic oscillator (2DLAHO) confining potential is analyzed as a
+function of the shape anisotropy, size and applied lateral electric field.",0910.4345v1
+2009-11-30,Magnetization reversal in amorphous Fe/Dy multilayers: a Monte Carlo study,"The Monte Carlo method in the canonical ensemble is used to investigate
+magnetization reversal in amorphous transition metal - rare earth multilayers.
+Our study is based on a model containing diluted clusters which exhibit an
+effective uniaxial anisotropy in competition with random magnetic anisotropy in
+the matrix. We simulate hysteresis loops for an abrupt profile and a diffuse
+one obtained from atom probe tomography analyses. Our results evidence that the
+atom probe tomography profile favors perpendicular magnetic anisotropy in
+agreement with magnetic measurements. Moreover, the hysteresis loops calculated
+at several temperatures qualitatively agree with the experimental ones.",0911.5653v1
+2010-03-30,Colossal anisotropy in diluted magnetic topological insulators,"We consider dilute magnetic doping in the surface of a three dimensional
+topological insulator where a two dimensional Dirac electron gas resides. We
+find that exchange coupling between magnetic atoms and the Dirac electrons has
+a strong and peculiar effect on both. First, the exchange-induced single ion
+magnetic anisotropy is very large and favors off-plane orientation. In the case
+of ferromagnetically ordered phase we find a colossal magnetic anisotropy
+energy, of the order of the critical temperature. Second, a persistent
+electronic current circulates around the magnetic atom and, in the case of a
+ferromagnetic phase, around the edges of the surface.",1003.5931v1
+2010-04-02,Late-time anisotropy and radiation drag within the cosmic microwave background,"I investigate the effect of the radiation drag force on a star moving
+relative to the Cosmic Microwave Background (CMB) at z = 0. As expected, the
+perturbation is extremely small and has no observable consequences on orbital
+motions of stars within a galaxy or on orbital motions of galaxies within a
+cluster. The energy dissipated by cubic meter in a galaxy via this mechanism is
+10^{14} smaller than the energy density of the CMB and, thus, is a negligible
+source of anisotropy. However, from the last scattering surface to population
+III stars (30 < z < 1000), radiation drag on particles may have played a major
+role in the apparition of anisotropy and rapid formation of densities.",1004.0328v1
+2010-05-10,Impact on cosmology of the celestial anisotropy of the short gamma-ray bursts,"Recently the anisotropy of the short gamma-ray bursts detected by BATSE was
+announced (Vavrek et al. 2008). The impact of this discovery on cosmology is
+discussed. It is shown that the anisotropy found may cause the breakdown of the
+cosmological principle.",1005.1558v1
+2010-07-19,CMB anisotropies in the presence of a stochastic magnetic field,"Primordial magnetic fields present since before the epoch of matter-radiation
+equality have an effect on the anisotropies of the cosmic microwave background.
+The CMB anisotropies due to scalar perturbations are calculated in the gauge
+invariant formalism for magnetized adiabatic initial conditions. Furthermore
+the linear matter power spectrum is calculated. Numerical solutions are
+complemented by a qualitative analysis.",1007.3163v2
+2010-09-29,Cosmic microwave anisotropies in an inhomogeneous compact flat universe,"The anisotropies of the cosmic microwave background (CMB) are computed for
+the half-turn space E_2 which represents a compact flat model of the Universe,
+i.e. one with finite volume. This model is inhomogeneous in the sense that the
+statistical properties of the CMB depend on the position of the observer within
+the fundamental cell. It is shown that the half-turn space describes the
+observed CMB anisotropies on large scales better than the concordance model
+with infinite volume. For most observer positions it matches the temperature
+correlation function even slightly better than the well studied 3-torus
+topology.",1009.5880v2
+2010-10-01,"Mapping the magnetic exchange interactions from first principles: Anisotropy anomaly and application to Fe, Ni, and Co","Mapping the magnetic exchange interactions from model Hamiltonian to density
+functional theory is a crucial step in multi-scale modeling calculations.
+Considering the usual magnetic force theorem but with arbitrary rotational
+angles of the spin moments, a spurious anisotropy in the standard mapping
+procedure is shown to occur provided by bilinear-like contributions of high
+order spin interactions. The evaluation of this anisotropy gives a hint on the
+strength of non-bilinear terms characterizing the system under investigation.",1010.0273v2
+2010-11-11,Anisotropic spin Hall effect from first principles,"We report on first principles calculations of the anisotropy of the intrinsic
+spin Hall conductivity (SHC) in nonmagnetic hcp metals and in antiferromagnetic
+Cr. For most of the metals of this study we find large anisotropies. We derive
+the general relation between the SHC vector and the direction of spin
+polarization and discuss its consequences for hcp metals. Especially, it is
+predicted that for systems where the SHC changes sign due to the anisotropy the
+spin Hall effect may be tuned such that the spin polarization is parallel
+either to the electric field or to the spin current.",1011.2714v2
+2011-01-10,Magnetic measurement of the critical current anisotropy in coated conductors,"We determine the critical current anisotropy at maximum Lorentz force from
+hysteresis loops in a vibrating sample magnetometer. To eliminate the signal of
+spurious variable Lorentz force currents it is sufficient to cut the sample to
+a specific length, which is calculated from the position dependent sensitivity
+of the instrument. The procedure increases the resolution of the measurement
+and the results compare well to transport data on the same sample. As the
+electric field in magnetisation measurements is lower than in transport
+experiments the anisotropy at high currents (low temperatures and fields) can
+be measured without the need of making current contacts or any special sample
+preparation.",1101.1788v1
+2011-02-18,Perpendicular magnetic anisotropy of full-Heusler films in Pt/Co2FeAl/MgO trilayers,"We report on perpendicular magnetic anisotropy (PMA) in a Pt/Co2FeAl/MgO
+sandwiched structure with a thick Co2FeAl layer of 2-2.5 nm. The PMA is
+thermally stable that the anisotropy energy density Ku is 1.3{\times}106
+erg/cm3 for the structure with 2 nm Co2FeAl after annealing at 350 oC. The
+thicknesses of Co2FeAl and MgO layers greatly affect the PMA. Our results
+provide an effective way to realize relative thick perpendicularly magnetized
+Heusler alloy films.",1102.3802v1
+2011-05-09,A multiscale autocorrelation function for anisotropy studies,"In recent years many procedures have been proposed to check the anisotropy of
+a dataset. We present a new simple procedure, based on a scale dependent
+approach, to detect anisotropy signatures in a given distribution with
+particular attention to small dataset. The method provides a good
+discrimination power for both large and small datasets, even in presence of
+strong contaminating isotropic background. We present some applications to
+simulated datasets of events to investigate statistical features of the method
+and present and inspect its behavior under both the null or the alternative
+hypothesis.",1105.1604v1
+2011-06-22,Anisotropic super-spin at the end of a carbon nanotube,"Interaction-induced magnetism at the ends of carbon nanotubes is studied
+theoretically, with a special focus on magnetic anisotropies. Spin-orbit
+coupling, generally weak in ordinary graphene, is strongly enhanced in
+nanotubes. In combination with Coulomb interactions, this enhanced spin-orbit
+coupling gives rise to a super-spin at the ends of carbon nanotubes with an XY
+anisotropy on the order of 10 mK. Furthermore, it is shown that this anisotropy
+can be enhanced by more than one order of magnitude via a partial suppression
+of the super-spin.",1106.4549v1
+2011-07-29,Electron spin resonance shift in spin ladder compounds,"We analyze the effects of different coupling anisotropies in spin-1/2 ladder
+on the Electron Spin Resonance (ESR) shift. Combining a perturbative expression
+in the anisotropies with temperature dependent Density Matrix Renormalization
+Group (T-DMRG) computation of the short range correlations, we provide the full
+temperature and magnetic field evolution of the ESR paramagnetic shift. We show
+that for well chosen parameters the ESR shift can be in principle used to
+extract quantitatively the anisotropies and, as an example, discuss the
+material $\mathrm{(C_5H_{12}N)_2CuBr_4}$ (BPCB).",1107.5965v2
+2011-08-10,A route towards finding large magnetic anisotropy in nano-composites: application to a W$_{1-x}$Re$_x$/Fe multilayer,"We suggest here a novel nano-laminate, 5[Fe]/2[W$_x$Re$_{1-x}$] (x=0.6-0.8),
+with enhanced magnetic hardness in combination with a large saturation moment.
+The calculated magnetic anisotropy of this material reaches values of 5.3-7.0
+MJ/m$^3$, depending on alloying conditions. We also propose a recipe in how to
+identify other novel magnetic materials, such as nano-laminates and
+multilayers, with large magnetic anisotropy in combination with a high
+saturation moment.",1108.2105v1
+2011-09-07,Magnetic-field tuned anisotropy in superconducting Rb(x)Fe(2-y)Se(2),"The anisotropic superconducting properties of a Rb(x)Fe(2-y)Se(2) single
+crystal with transition temperature 32 K were investigated by means of SQUID
+and torque magnetometry, probing the effective magnetic penetration depth and
+the magnetic penetration depth anisotropy. Interestingly, the anisotropy is
+found to be temperature independent in the superconducting state, but strongly
+field dependent. This unusual anisotropic behavior, together with a large
+zero-temperature effective magnetic penetration depth is possibly related to a
+superconducting state heavily biased by the coexisting antiferromagnetic phase.",1109.1430v2
+2011-11-14,Electron spin resonance study of anisotropic interactions in a two-dimensional spin gap magnet PHCC,"Fine details of the excitation spectrum of the two-dimensional spin-gap
+magnet PHCC are revealed by electron spin resonance investigations. The values
+of anisotropy parameters and the orientations of the anisotropy axes are
+determined by accurate measurements of the angular, frequency-field and
+temperature dependences of the resonance absorption. The properties of a
+spin-gap magnet in the vicinity of critical field are discussed in terms of
+sublevel splittings and g-factor anisotropy.",1111.3223v1
+2012-01-06,Anisotropic magneto-resistance in a GaMnAs-based single impurity tunnel diode: a tight binding approach,"Using an advanced tight-binding approach, we estimate the anisotropy of the
+tunnel transmission associated with the rotation of the 5/2 spin of a single Mn
+atom forming an acceptor state in GaAs and located near an AlGaAs tunnel
+barrier. Significant anisotropies in both in-plane and out-of-plane geometries
+are found, resulting from the combination of the large spin-orbit coupling
+associated with the p-d exchange interaction, cubic anisotropy of heavy-hole
+dispersion and the low C2v symmetry of the chemical bonds.",1201.1439v1
+2012-01-11,Local magnetic anisotropy in BaFe$_2$As$_2$: a polarized inelastic neutron scattering study,"The anisotropy of the magnetic excitations in BaFe$_2$As$_2$ was studied by
+polarized inelastic neutron scattering which allows one to separate the
+components of the magnetic response. Despite the in-plane orientation of the
+static ordered moment we find the in-plane polarized magnons to exhibit a
+larger gap than the out-of-plane polarized ones indicating very strong
+single-ion anisotropy within the layers. It costs more energy to rotate a spin
+within the orthorhombic {\it a-b} plane than rotating it perpendicular to the
+FeAs layers.",1201.2332v1
+2012-01-23,Strong Enhancement of Rashba spin-orbit coupling with increasing anisotropy in the Fock-Darwin states of a quantum dot,"We have investigated the electronic properties of elliptical quantum dots in
+a perpendicular external magnetic field, and in the presence of the Rashba
+spin-orbit interaction. Our work indicates that the Fock-Darwin spectra display
+strong signature of Rashba spin-orbit coupling even for a low magnetic field,
+as the anisotropy of the quantum dot is increased. An explanation of this
+pronounced effect with respect to the anisotropy is presented. The strong
+spin-orbit coupling effect manifests itself prominently in the corresponding
+dipole-allowed optical transitions, and hence is susceptible to direct
+experimental observation.",1201.4842v2
+2012-01-26,Self-assembly of anisotropic soft particles in two dimensions,"The self assembly of core-corona discs interacting via anisotropic potentials
+is investigated using Monte Carlo computer simulations. A minimal interaction
+potential that incorporates anisotropy in a simple way is introduced. It
+consists in a core-corona architecture in which the center of the core is
+shifted with respect to the center of the corona. Anisotropy can thus be tuned
+by progressively shifting the position of the core. Despite its simplicity, the
+system self organize in a rich variety of structures including stripes,
+triangular and rectangular lattices, and unusual plastic crystals. Our results
+indicate that the amount of anisotropy does not alter the lattice spacing and
+only influences the type of clustering (stripes, micells, etc.) of the
+individual particles.",1201.5440v1
+2012-02-15,Origin of bulk uniaxial anisotropy in zinc-blende dilute magnetic semiconductors,"It is demonstrated that the nearest neighbor Mn pair on the GaAs (001)
+surface has a lower energy for the [-110] direction comparing to the [110]
+case. According to the group theory and the Luttinger's method of invariants,
+this specific Mn distribution results in bulk uniaxial in-plane and
+out-of-plane anisotropies. The sign and magnitude of the corresponding
+anisotropy energies determined by a perturbation method and ab initio
+computations are consistent with experimental results.",1202.3295v1
+2012-02-29,Dynamic Critical Behavior of the Heisenberg Model with Strong Easy Plane Anisotropy,"The dynamic critical behavior of the Heisenberg model with a strong
+anisotropy of the exchange constant in the z direction is investigated. The
+main features of the time evolution of this model are revealed. The static and
+dynamic critical behavior of planar magnetic models is shown to be described
+well by the Heisenberg model with strong easy plane anisotropy.",1202.6509v1
+2012-03-23,Magnetic dispersion and anisotropy in multiferroic BiFeO3,"We have determined the full magnetic dispersion relations of multiferroic
+BiFeO3. In particular, two excitation gaps originating from magnetic
+anisotropies have been clearly observed. The direct observation of the gaps
+enables us to accurately determine the Dzyaloshinskii-Moriya (DM) interaction
+and the single ion anisotropy. The DM interaction supports a strong
+magneto-electric coupling in this compound.",1203.5294v3
+2012-03-30,Highly anisotropic temperature balance equation and its asymptotic-preserving resolution,"This paper deals with the numerical study of a nonlinear, strongly
+anisotropic heat equation. The use of standard schemes in this situation leads
+to poor results, due to the high anisotropy. An Asymptotic-Preserving method is
+introduced in this paper, which is second-order accurate in both, temporal and
+spacial variables. The discretization in time is done using an L-stable
+Runge-Kutta scheme. The convergence of the method is shown to be independent of
+the anisotropy parameter $0 < \eps <1$, and this for fixed coarse Cartesian
+grids and for variable anisotropy directions. The context of this work are
+magnetically confined fusion plasmas.",1203.6739v1
+2012-04-17,Magnetic anisotropy of YbNi4P2,"We report on transport and magnetic measurements between 1.8 and 400 K on
+single crystalline YbNi4P2, which was recently reported to be a heavy fermion
+system with a low lying ferromagnetic transition at T_C=0.17 K, based on data
+from polycrystals. The tetragonal crystal structure of YbNi4P2 presents
+quasi-one-dimensional Yb chains along the c direction. Here we show that at
+high temperatures, the magnetic anisotropy of YbNi4P2 is dominated by the
+crystal electrical field effect with an Ising-type behaviour, which gets more
+pronounced towards lower temperatures. The electrical resistivity also reflects
+the strong anisotropy of the crystal structure and favours transport along c,
+the direction of the Yb chains.",1204.3759v1
+2012-06-05,Cosmic ray transport and anisotropies,"We show that the large-scale cosmic ray anisotropy at ~10 TeV can be
+explained by a modified Compton-Getting effect in the magnetized flow field of
+old supernova remnants. This approach suggests an optimum energy scale for
+detecting the anisotropy. Two key assumptions are that propagation is based on
+turbulence following a Kolmogorov law and that cosmic ray interactions are
+dominated by transport through stellar winds of the exploding stars. A
+prediction is that the amplitude is smaller at lower energies due to incomplete
+sampling of the velocity field and also smaller at larger energies due to
+smearing.",1206.0828v1
+2012-06-26,Entanglement and Sources of Magnetic Anisotropy in Radical Pair-Based Avian Magnetoreceptors,"One of the principal models of magnetic sensing in migratory birds rests on
+the quantum spin-dynamics of transient radical pairs created photochemically in
+ocular cryptochrome proteins. We consider here the role of electron spin
+entanglement and coherence in determining the sensitivity of a radical
+pair-based geomagnetic compass and the origins of the directional response. It
+emerges that the anisotropy of radical pairs formed from spin-polarized
+molecular triplets could form the basis of a more sensitive compass sensor than
+one founded on the conventional hyperfine-anisotropy model. This property
+offers new and more flexible opportunities for the design of biologically
+inspired magnetic compass sensors.",1206.5946v1
+2012-07-17,The anisotropy properties of a background radiation in the fractal cosmological model,"We consider the anisotropy properties of a background radiation in the
+fractal cosmological model. The space of this model includes self-similar
+domains. The metric tensors of any two domains are connected by the discrete
+scaling transformation. Photons of the background radiation cross the domain
+and their energy change. Any observer receives these photons from different
+domains and detects spots with different brightness. The power spectrum of the
+brightness anisotropy of the background radiation in the fractal cosmological
+model is calculated. It is shown this spectrum is closed to the observed
+angular power spectrum of the SDSS-quasar distribution on the celestial sphere.
+Only qualitatively it conforms to the angular power spectrum of CMB (WMAP-7).",1207.4615v1
+2012-08-10,Transversal Magnetic Anisotropy in Nanoscale PdNi-Strips,"We investigate submicron ferromagnetic PdNi thin-film strips intended as
+contact electrodes for carbon nanotube-based spintronic devices. The magnetic
+anisotropy and micromagnetic structure are measured as function of temperature
+and aspect ratio. Contrary to the expectation from shape anisotropy, magnetic
+hysteresis measurements of Pd0.3Ni0.7 on arrays containing strips of various
+width point towards a magnetically easy axis in the sample plane, but
+transversal to the strip direction. Anisotropic magnetoresistance measured on
+individual Pd0.3Ni0.7 contact strips and magnetic force microscopy images
+substantiate that conclusion.",1208.2163v2
+2012-08-29,Implications of mirror dark matter kinetic mixing for CMB anisotropies,"Mirror dark matter is a dissipative and self-interacting multiparticle dark
+matter candidate which can explain the DAMA, CoGeNT and CRESST-II direct
+detection experiments. This explanation requires photon-mirror photon kinetic
+mixing of strength $\epsilon \sim 10^{-9}$. Mirror dark matter with such
+kinetic mixing can potentially leave distinctive signatures on the CMB
+anisotropy spectrum. We show that the most important effect of kinetic mixing
+on the CMB anisotropies is the suppression of the height of the third and
+higher odd peaks. If $\epsilon \stackrel{>}{\sim} 10^{-9}$ then this feature
+can be observed by the PLANCK mission in the near future.",1208.6022v2
+2012-09-12,Coherent spin control by electrical manipulation of the magnetic anisotropy,"High-spin paramagnetic manganese defects in polar piezoelectric zinc oxide
+exhibit a simple almost axial anisotropy and phase coherence times of the order
+of a millisecond at low temperatures. The anisotropy energy is tunable using an
+externally applied electric field. This can be used to control electrically the
+phase of spin superpositions and to drive spin transitions with resonant
+microwave electric fields.",1209.2745v2
+2012-10-24,Origin of the Large Anisotropy in the χ_3 Anomaly in URu_2Si_2,"Motivated by recent quantum oscillations experiments on URu_2Si_2, we discuss
+the microscopic origin of the large anisotropy observed many years ago in the
+anomaly of the nonlinear susceptibility in this same material. We show that the
+magnitude of this anomaly emerges naturally from hastatic order, a proposal for
+hidden order that is a two-component spinor arising from the hybridization of a
+non-Kramers Gamma_5 doublet with Kramers conduction electrons. A prediction is
+made for the angular anisotropy of the nonlinear susceptibility anomaly as a
+test of this proposed order parameter for URu_2Si_2.",1210.6425v1
+2012-11-22,Power spectrum and anisotropy of super inflation in loop quantum cosmology,"We investigate the scalar mode of perturbation of super inflation in the
+version of loop quantum cosmology in which the gauge invariant holonomy
+corrections are considered. Given a background solution, we calculate the power
+spectrum of the perturbation in the classical and LQC conditions. Then we
+compute the anisotropy originated from the perturbation. It is found that in
+the presence of the gauge invariant holonomy corrections the power spectrum is
+exponentially blue and the anisotropy also grows exponentially in the epoch of
+super inflation.",1211.5310v2
+2012-12-28,A Study on Anisotropy in the Arrival Directions of Ultra-High-Energy Cosmic Rays Observed by Pierre Auger Observatory,"We study the anisotropy in the arrival directions of PAO UHECRs, using the
+point source correlational angular distance distribution. The result shows that
+the anisotropy is characterized by one prominent excess region and one void
+region. The excess region is located near the Centaurus A direction, supporting
+that the Centaurus A is a promising UHECR source. The void region near the
+south pole direction may be used to limit the diffuse isotropic background
+contribution.",1212.6479v1
+2013-02-02,Physics in a general length space-time geometry: Call for experimental revision of the light speed anisotropy,"We present a phenomenological model for the nature in the Finsler and Randers
+space-time geometries. We show that the parity-odd light speed anisotropy
+perpendicular to the gravitational equipotential surfaces encodes the deviation
+from the Riemann geometry toward the Randers geometry. We utilize an
+asymmetrical ring resonator and propose a setup in order to directly measure
+this deviation. We address the constraints that the current technology will
+impose on the deviation should the anisotropy be measured on the Earth surface
+and the orbits of artificial satellites.",1302.1194v1
+2013-05-23,Searches for Large-Scale Anisotropies of Cosmic Rays: Harmonic Analysis and Shuffling Technique,"The measurement of large scale anisotropies in cosmic ray arrival directions
+is generally performed through harmonic analyses of the right ascension
+distribution as a function of energy. These measurements are challenging due to
+the small expected anisotropies and meanwhile the relatively large modulations
+of observed counting rates due to experimental effects. In this paper, we
+present a procedure based on the shuffling technique to carry out these
+measurements, applicable to any cosmic ray detector without any additional
+corrections for the observed counting rates.",1305.5401v1
+2013-06-21,Specific Heat and Upper Critical Field of Sc5Ir4Si10 Superconductor,"Temperature and magnetic field dependent specific heat of textured Sc5Ir4Si10
+superconductor was investigated in detail. Based on the fitting of zero-field
+electronic specific heat by different gap structures as well as the discussion
+on field-induced specific heat coefficient, Sc5Ir4Si10 is proved to be an
+anisotropic s-wave superconductor with a gap anisotropy of 0.53. The anisotropy
+of upper critical field suggests the weakly one-dimensional Fermi surface, and
+the value is consistent with the gap anisotropy result obtained from the
+specific heat data.",1306.5027v1
+2013-07-12,Non-Stationary Measurements of Chiral Magnetic Effect,"We discuss Chiral Magnetic Effect from quantum theory of measurements point
+of view for non-stationary measurements. The effect of anisotropy for
+fluctuations of electric currents in magnetic field is addressed. It is shown
+that anisotropy caused by nonzero axial chemical potential is indistinguishable
+in this framework from anisotropy caused by finite measurement time or finite
+lifetime of the magnetic field, and in all cases it is related to abelian
+triangle anomaly. Possible P-odd effects for central heavy ions collisions
+(where Chiral Magnetic Effect is absent) are discussed in this context.",1307.3444v1
+2013-09-11,Non compound nucleus fission events and standard saddle-point statistical model,"The large body of experimental data on the fission fragments anisotropies are
+analyzed in several heavy-ion induced fission reaction systems. The entrance
+channel mass asymmetry parameters of these systems put on the both sides of the
+Businaro-Gallone mass asymmetry parameters. The role of the mass numbers of the
+projectile and the target in the prediction of a normal or an anomalous
+behavior in angular anisotropy, as well as the validity of standard
+saddle-point statistical model are considered. The average contribution of non
+compound nucleus fission for the systems with an anomalous behavior in
+anisotropy are also determined. PACS numbers: 25.70.Jj *Corresponding author:
+s.soheyli@basu.ac.ir",1309.2738v1
+2013-09-11,Geometry of Compressible and Incompressible Quantum Hall States: Application to Anisotropic Composite Fermion Liquids,"Haldane's geometrical description of fractional quantum Hall states is
+generalized to compressible states. It is shown that anisotropy in the
+composite fermion Fermi surface is a direct reflection of this intrinsic
+geometry. A simple model is introduced in which the geometric parameter can be
+obtained exactly from other parameters including electron mass anisotropy. Our
+results compare favorably with recent measurements of anisotropy in composite
+fermion Fermi surface [D. Kamburov, Y. Liu, M. Shayegan, L. N. Pfeiffer, K. W.
+West, and K. W. Baldwin, Phys. Rev. Lett. 110, 206801 (2013)]. Broader
+implications of our results are discussed.",1309.2830v2
+2013-09-12,Structural control of magnetic anisotropy in a strain driven multiferroic EuTiO3 thin film,"Octahedral distortion plays a key role in engineering the physical properties
+of heterostructures composed of perovskite oxides. We observe a strong in-plane
+uniaxial magnetic anisotropy in a strain-enabled multiferroic EuTiO3 thin film
+epitaxially grown on a (110)o DyScO3 substrate. First principles calculations
+show that the magnetic anisotropy is closely correlated with the uniaxial TiO6
+octahedral tilting and the ferroelectric polarization of the film, indicating
+potential strong magnetoelectric coupling in the strain-engineered multiferroic
+system.",1309.3185v1
+2013-11-27,Effects of Surface Anisotropy on Magnetic Vortex Core,"The vortex core shape in the three dimensional Heisenberg magnet is
+essentially influenced by a surface anisotropy. We predict that depending of
+the surface anisotropy type there appears barrel- or pillow-shaped deformation
+of the vortex core along the magnet thickness. Our theoretical study is well
+confirmed by spin-lattice simulations.",1311.6882v1
+2014-01-06,Anisotropic Hydrodynamics: Motivation and Methodology,"In this proceedings contribution I review recent progress in our
+understanding of the bulk dynamics of relativistic systems that possess
+potentially large local rest frame momentum-space anisotropies. In order to
+deal with these momentum-space anisotropies, a reorganization of relativistic
+viscous hydrodynamics can been made around an anisotropic background, and the
+resulting dynamical framework has been dubbed ""anisotropic hydrodynamics."" I
+also discuss expectations for the degree of momentum-space anisotropy of the
+quark gluon plasma generated in relativistic heavy ion collisions at RHIC and
+LHC from second-order viscous hydrodynamics, strong-coupling approaches, and
+weak-coupling approaches.",1401.1188v1
+2014-01-25,A holographic superconductor model in a spatially anisotropic background,"We investigate an anisotropic model of superconductors in the
+Einstein-Maxwell-dilaton theory with a charged scalar field. It is found that
+the critical temperature decreases as the anisotropy becomes large. We then
+estimate the energy gap of the superconductor, and find that the ratio of the
+energy gap to the critical temperature increases as the anisotropy increases
+and so it is larger than that in the isotropic case. We also find that peudogap
+appears due to the anisotropy.",1401.6501v3
+2014-02-24,Compensation of anisotropy effects in the generation of two-photon light,"We analyse a method to compensate for anisotropy effects in the spatial
+distribution of parametric down-conversion (PDC) radiation in bulk crystals. In
+this method, a single nonlinear crystal is replaced by two consecutive crystals
+with opposite transverse walk-off directions. We implement a simple numerical
+model to calculate the spatial distribution of intensity and correlations, as
+well as the Schmidt mode structure, with an account for the anisotropy.
+Experimental results are presented which prove the validity of both the model
+and the method.",1402.5888v1
+2014-08-27,Anderson Localization of Matter Waves in 3D Anisotropic Disordered Potentials,"Using a cutoff-free formulation of the coherent transport theory, we show
+that the interference terms at the origin of localization strongly affect the
+transport anisotropy. In contrast to the common hypothesis, we then find that
+the anisotropies of incoherent and coherent diffusion are significantly
+different, in particular at criticality. There, we show that the coherent
+transport anisotropy is mainly determined by the properties of the
+disorder-averaged effective scattering medium while the incoherent transport
+contributions become irrelevant.",1408.6387v2
+2014-10-05,Models for Quark Stars with Charged Anisotropic Matter,"In this paper, we found new exact solutions to the Einstein- Maxwell system
+of equations within the framework of MIT Bag Model considering a particular
+form for the measure of anisotropy and a gravitational potential which depends
+on an adjustable parameter {\alpha}. Variables as the energy density, radial
+pressure, tangential pressure, electric field intensity and the metric
+functions are written in terms of elementary and polinominal functions. We show
+that the form chosen for the gravitational potential and the anisotropy allows
+obtain physically acceptable solutions with any value of the adjustable
+parameter.",1410.1524v1
+2014-10-26,"Drag force in strongly coupled, anisotropic plasma at finite chemical potential","We employ methods of gauge/string duality to analyze the drag force on a
+heavy quark moving through a strongly coupled, anisotropic \mathcal{N}=4, SU(N)
+super Yang- Mills plasma in the presence of a finite U(1) chemical potential.
+We present numerical results valid for any value of the anisotropy parameter
+and the U(1) charge density and arbitrary direction of the quark velocity with
+respect to the direction of anisotropy. In the small anisotropy limit we are
+also able to furnish analytical results.",1410.7040v1
+2014-11-30,Spin dynamics of the anisotropic spin-1 antiferromagnetic chain at finite magnetic fields,"We present results of a study of the antiferromagnetic spin-1 chain, subject
+to the simultaneous presence of single-ion anisotropy and external magnetic
+fields. Using quantum Monte-Carlo based on the stochastic series expansion
+method we first uncover a rich quantum phase diagram comprising N\'eel,
+Haldane, Luttinger liquid, and large anisotropy phases. Second, we scan across
+this phase diagram over a wide range of parameters, evaluating the transverse
+dynamic structure factor, which we show to exhibit sharp massive modes, as well
+as multi particle continua. For vanishing anisotropy and fields, comparison
+with existing results from other analytic and numerical approaches shows
+convincing consistency.",1412.0208v2
+2014-12-11,Possible origin of nonlinear magnetic anisotropy variation in electric field effect in a double interface system,"We investigated the effect of an electric field on the interface magnetic
+anisotropy of a thin MgO/Fe/MgO layer using density functional theory. The
+perpendicular magnetic anisotropy energy (MAE) increases not only under
+electron depletion but also under some electron accumulation conditions,
+showing a strong correlation with the number of electrons on the interface Fe
+atom. The reverse variation in the MAE under the electric field is ascribed to
+novel features on the charged interface, such as electron leakage. We discuss
+the origin of the variation in terms of the electronic structures.",1412.3577v1
+2015-01-08,Theoretical evaluation on the temperature dependence of magnetic anisotropy constants of Nd2Fe14B - Effects of exchange field and crystal field strength -,"To identify the possible mechanism of coercivity (Hc) degradation of Nd-Fe-B
+sintered magnets, we study the roles of the exchange field acting on the 4f
+electrons in Nd ions and theoretically investigate how the variation of the
+exchange field affects the values of the magnetic anisotropy constants K1 and
+K2. We find that, with decreasing exchange field strength, both values decrease
+as a result of the lower asphericity of the 4f electron cloud, indicating that
+the local anisotropy constants might become small around the grain boundaries
+where the exchange fields are decreased owing to the smaller coordination
+number.",1501.01782v1
+2015-03-04,Geodesic Acoustic Mode in Toroidally Rotating Anisotropic Tokamaks,"Effects of anisotropy on the geodesic acoustic mode (GAM) is analyzed by
+using gyro-kinetic equations applicable to low-frequency microinstabilities in
+a toroidally rotating tokamak plasma. Dispersion relation in the presence of
+arbitrary Mach number $M$, anisotropy strength $\sigma$, and the temperature
+ration $\tau$ is analytically derived. It is shown that when $\sigma$ is less
+than $ 3 + 2 \tau$, the increased electron temperature with fixed ion parallel
+temperature increases the normalized GAM frequency. When $\sigma$ is larger
+than $ 3 + 2 \tau$, the increasing of electron temperature decreases the GAM
+frequency. The anisotropy $\sigma$ always tends to enlarge the GAM frequency.
+The Landau damping rate is dramatically decreased by the increasing $\tau$ or
+$\sigma$.",1503.01315v1
+2015-05-20,Ultra-directional super-scattering of homogenous spherical particles with radial anisotropy,"We study the light scattering of homogenous radially-anisotropic spherical
+particles. It is shown that radial anisotropy can be employed to tune
+effectively the electric resonances, and thus enable flexible overlapping of
+electric and magnetic dipoles of various numbers, which leads to unidirectional
+forward super-scattering at different spectral positions. We further reveal
+that through adjusting the radial anisotropy parameters, electric and magnetic
+resonances of higher orders can be also made overlapped, thus further
+collimating the forward scattering lobes. The ultra-directional
+super-scattering we have obtained with individual homogenous radially
+anisotropic spherical particles may shed new light to the design of compact and
+efficient nanoantennas, which may find various applications in solar cells,
+bio-sensing and many other antenna based researches.",1505.05340v1
+2015-12-07,Power spectrum of flow fluctuations in relativistic heavy-ion collisions,"We carry out hydrodynamical simulation of the evolution of fluid in
+relativistic heavy-ion collisions with random initial fluctuations. The time
+evolution of power spectrum of momentum anisotropies shows very strong
+correspondence with the physics of cosmic microwave anisotropies as was earlier
+predicted by some of us. In particular our results demonstrate suppression of
+superhorizon fluctuations and the correspondence between the location of the
+first peak in the power spectrum of momentum anisotropies and the length scale
+of fluctuations and expected freezeout time scale (more precisely, the sound
+horizon size at freezeout).",1512.02136v1
+2015-12-08,Anisotropic Inflation with General Potentials,"Anomalies in recent observational data indicate that there might be some
+""anisotropic hair"" generated in an inflation period. To obtain general
+information about the effects of this anisotropic hair to inflation models, we
+studied anisotropic inflation models that involve one vector and one scalar
+using several types of potentials. We determined the general relationship
+between the degree of anisotropy and the fraction of the vector and scalar
+fields, and concluded that the anisotropies behave independently of the
+potentials. We also generalized our study to the case of multi-directional
+anisotropies.",1512.02316v1
+2015-12-09,Pressure anisotropy generation in a magnetized plasma configuration with a shear flow velocity,"The nonlinear evolution of the Kelvin Helmholtz instability in a magnetized
+plasma with a perpendicular flow close to, or in, the supermagnetosonic regime
+can produce a significant parallel-to-perpendicular pressure anisotropy. This
+anisotropy, localized inside the flow shear region, can make the configuration
+unstable either to the mirror or to the firehose instability and, in general,
+can affect the development of the KHI. The interface between the solar wind and
+the Earth's magnetospheric plasma at the magnetospheric equatorial flanks
+provides a relevant setting for the development of this complex nonlinear
+dynamics.",1512.02917v1
+2016-02-29,Anisotropic thermal expansion of bismuth from first principles,"Some anisotropy in both mechanical and thermodynamical properties of bismuth
+is expected. A combination of density functional theory total energy
+calculations and density functional perturbation theory in the local density
+approximation is used to compute the elastic constants at 0 K using a finite
+strain approach and the thermal expansion tensor in the quasiharmonic
+approximation. The overall agreement with experiment is good. Furthermore, the
+anisotropy in the thermal expansion is found to arise from the anisotropy in
+both the directional compressibilities and the directional Gr\""uneisen
+functions.",1602.08959v1
+2016-03-10,"The anisotropy induced by defects of ""random local field"" type in O(n) models and suppression of the Imry-Ma inhomogeneous state","We demonstrate that in the system with anisotropic distribution of the
+defect-induced random local field directions in the n-dimensional space of
+vector order parameter with the O(n) symmetry, the defect-induced effective
+anisotropy arises for the space dimensionality 2<d<4. If the anisotropy
+constant exceeds the threshold value, then an inhomogeneous state predicted by
+Imry and Ma becomes energetically unfavorable, and the system goes back to the
+state with the long-range order.",1603.03360v1
+2016-03-13,Perpendicular magnetic anisotropy in Co$_2$Fe$_{0.4}$Mn$_{0.6}$Si,"We report perpendicular magnetic anisotropy (PMA) in the half-metallic
+ferromagnetic Heusler alloy Co$_2$Fe$_{0.4}$Mn$_{0.6}$Si (CFMS) in a
+MgO/CFMS/Pd trilayer stack. PMA is found for CFMS thicknesses between 1 and 2
+nm, with a magnetic anisotropy energy density of $K_U = 1.5\times 10^6$
+erg/cm$^3$ for t$_{\tiny \textrm{CFMS}} = 1.5$ nm. Both the MgO and Pd layer
+are necessary to induce the PMA. We measure a tunable anomalous Hall effect,
+where its sign and magnitude vary with both the CFMS and Pd thickness.",1603.04072v1
+2016-04-12,Magnetization distribution and domain wall dynamics in nanotube with surface anisotropy,"The period of magnetization oscillations that occur near the surface of a
+nanotube or nanowire under the influence of surface magnetic anisotropy is
+determined by means of numerical simulation as a function of nanowire geometry
+and material parameters. The hopping mode is observed for stationary movement
+of a head-to-head domain wall along nanowire axis in applied magnetic field.
+The average speed of the domain wall in the hopping mode is found to be several
+times less than the stationary velocity of the wall in the absence of surface
+anisotropy.",1604.03523v1
+2016-04-14,A comparison of functional summary statistics to detect anisotropy of three-dimensional point patterns,"The growing availability of three-dimensional point process data asks for a
+development of suitable analysis techniques. In this paper, we focus on two
+recently developed summary statistics, the conical and the cylindrical
+$K$-function, which may be used to detect anisotropies in 3D point patterns. We
+give some recommendations on choosing their arguments and investigate their
+ability to detect two special types of anisotropy. Finally, both functions are
+compared on some real data sets from neuroscience and glaciology.",1604.04211v1
+2016-04-16,Beyond the upper limit of magnetic anisotropy in two-dimensional transition metal dichalcogenides,"Exploring an upper limit of magnetic anisotropy in two-dimensional materials,
+such as graphene and transition metal dichalcogenides, is at the heart of
+spintronics research. Herein, an atomic-scale perpendicular magnetic anisotropy
+up to an order of 100 meV per atom, which is far beyond the ordinarily obtained
+value in graphene and pristine transition metal dichalcogenides, is
+demonstrated in individual ruthenium and osmium adatoms at a monosulfur vacancy
+in molybdenum disulfide. We further propose a phenomenological model where a
+spin state transition that involves hybridization between molybdenum a1 and
+adatomic e' orbitals is a possible mechanism for magnetization reorientation.",1604.04708v1
+2016-04-19,Multichannel Scattering and Loss Processes of Ultracold Atoms in Anisotropic Harmonic Waveguides,"We have developed the general grid method for multi-channel scattering of
+bosonic atoms inside a harmonic waveguide with transverse anisotropy. This
+approach is employed to analyze elastic as well as inelastic multi-channel
+confined scattering. For the elastic scattering, the effects of the range and
+form of interatomic potential and the waveguide anisotropy on the confinement
+induced resonance are studied. We have also investigated quantitatively the
+reactive rate constant in confined atom-atom collisions. It is found that a
+slight anisotropy to the confining trap considerably enhances the reactive rate
+constant in multi-channel regime.",1604.05457v2
+2016-05-20,Interlayer interaction in multilayer CoPt/Co structures,"We report a study of interlayer exchange interaction in multilayer CoPt/Co
+structures consisting of periodic CoPt multilayer film with an ""easy axis""
+anisotropy and thick Co layer with an ""easy plane"" anisotropy separated by Pt
+spacer with variable thickness. The magnetooptical Kerr effect (MOKE) and
+ferromagnetic resonance (FMR) measurements show up the essentially
+non-collinear state of magnetic moments of the layers and strong exchange
+coupling between CoPt and Co subsystems. The estimation of effective anisotropy
+and exchange coupling in a simple model based on the Landau-Lifshitz-Gilbert
+equation describing magnetization dynamics was performed.",1605.06468v1
+2016-06-09,Spacetime anisotropy affects cosmological entanglement,"Most existing cosmological entanglement studies are focused on the isotropic
+Robertson-Walker (RW) spacetime. Here we go beyond this limitation and study
+the influence of anisotropy on entanglement generated by dynamical spacetime.
+Since the isotropic spacetime is viewed as a background medium and the
+anisotropy is incorporated as perturbation, we decompose entanglement entropy
+into isotropic and anisotropic contributions. The latter is shown to be
+non-negligible by analyzing two cosmological models with weak and conformal
+coupling. We also show the possibility of using entanglement to infer about
+universe features.",1606.03005v1
+2016-06-10,Self-induced glassiness and pattern formation in spin systems subject to long-range interactions,"We study the glass formation in two- and three-dimensional Ising and
+Heisenberg spin systems subject to competing interactions and uniaxial
+anisotropy with a mean-field approach. In three dimensions, for sufficiently
+strong anisotropy the systems always modulates in a striped phase. Below a
+critical strength of the anisotropy, a glassy phase exists in a finite range of
+temperature, and it becomes more stable as the system becomes more isotropic.
+In two dimension the criticality is always avoided and the glassy phase always
+exists.",1606.03458v1
+2016-06-30,"Helicity, anisotropies and their competition in a multiferroic magnet: insight from the phase diagram","Motivated by the complex phase diagram of MnWO4, we investigate competition
+between anisotropy, magnetic field, and helicity for the anisotropic
+next-nearest-neighbor Heisenberg model. Apart from two competing exchanges,
+which favor a spiral magnetic structure, the model features the bi-axial
+single-ion anisotropy. The model is treated in the real-space mean-field
+approximation and the phase diagram containing various incommensurate and
+commensurate states is obtained for different field orientations. We discuss
+similarities and differences of the theoretical phase diagram and the
+experimental diagram of MnWO4.",1606.09381v2
+2016-08-25,Thermodynamic Measurement of Angular Anisotropy at the Hidden Order Transition of URu$_2$Si$_2$,"The heavy fermion compound URu$_2$Si$_2$ continues to attract great interest
+due to the unidentified hidden order it develops below 17.5K. The unique Ising
+character of the spin fluctuations and low temperature quasiparticles is well
+established. We present detailed measurements of the angular anisotropy of the
+nonlinear magnetization that reveal a $\cos^4 \theta$ Ising anisotropy both at
+and above the ordering transition. With Landau theory, we show this implies a
+strongly Ising character of the itinerant hidden order parameter.",1608.07009v1
+2016-09-09,Probing pre-inflationary anisotropy with directional variations in the gravitational wave background,"We perform a detailed analysis on a primordial gravitational-wave background
+amplified during a Kasner-like pre-inflationary phase allowing for general
+triaxial anisotropies. It is found that the predicted angular distribution map
+of gravitational-wave intensity on large scales exhibits topologically
+distinctive patterns according to the degree of the pre-inflationary
+anisotropy, thereby serving as a potential probe for the pre-inflationary early
+universe with future all-sky observations of gravitational waves. We also
+derive an observational limit on the amplitude of such anisotropic
+gravitational waves from the B-mode polarisation of the cosmic microwave
+background.",1609.02785v1
+2016-09-21,Mobility anisotropy of two-dimensional semiconductors,"The carrier mobility of anisotropic two-dimensional (2D) semiconductors under
+longitudinal acoustic (LA) phonon scattering was theoretically studied with the
+deformation potential theory. Based on Boltzmann equation with relaxation time
+approximation, an analytic formula of intrinsic anisotropic mobility was
+deduced, which shows that the influence of effective mass to the mobility
+anisotropy is larger than that of deformation potential constant and elastic
+modulus. Parameters were collected for various anisotropic 2D materials (black
+phosphorus, Hittorf's phosphorus, BC$_2$N, MXene, TiS$_3$, GeCH$_3$) to
+calculate their mobility anisotropy. It was revealed that the anisotropic ratio
+was overestimated in the past.",1609.06416v1
+2016-10-26,Classical spin liquid instability driven by off-diagonal exchange in strong spin-orbit magnets,"We show that the off-diagonal exchange anisotropy drives Mott insulators with
+strong spin-orbit coupling to a classical spin liquid regime, characterized by
+an infinite number of ground states and Ising variables living on closed or
+open strings. Depending on the sign of the anisotropy, quantum fluctuations
+either fail to lift the degeneracy down to very low temperatures, or select
+non-collinear magnetic states with unconventional spin correlations. The
+results apply to all 2D and 3D tri-coordinated materials with bond-directional
+anisotropy, and provide a consistent interpretation of the suppression of the
+x-ray magnetic circular dichroism signal reported recently for
+$\beta$-Li$_2$IrO$_3$ under pressure.",1610.08463v1
+2016-11-16,Perpendicular magnetic anisotropy in Co$_2$MnGa,"We report perpendicular magnetic anisotropy in the ferromagnetic Heusler
+alloy Co$_2$MnGa in a MgO/Co$_2$MnGa/Pd trilayer stack for Co$_2$MnGa
+thicknesses up to 3.5 nm. There is a thickness- and temperature-dependent spin
+reorientation transition from perpendicular to in-plane magnetic anisotropy
+which we study through the anomalous Hall effect. From the temperature
+dependence of the anomalous Hall effect, we observe the expected scaling of
+$\rho_{xy}^{AHE}$ with $\rho_{xx}$, suggesting the intrinsic and side-jump
+mechanisms are largely responsible for the anomalous Hall effect in this
+material.",1611.05110v1
+2016-12-28,Search for Cosmic Ray Anisotropy with the Alpha Magnetic Spectrometer on the International Space Station,"The search for cosmic ray anisotropy has been performed using particles
+collected by the Alpha Magnetic Spectrometer after the first five years of
+operation. The positron to electron ratio is consistent with isotropy at all
+energies and angular scales. The limit on the dipole anisotropy at the 95%
+confidence level for energies above 16GeV is $\delta<0.020$ for positrons and
+$\delta<0.006$ for electrons. In the case of high rigidity protons the upper
+limit in the rigidity range from 80 to 1800GV is $\delta<0.003$. No indication
+of seasonal excess is observed for all particle species within the present
+statistics.",1612.08957v1
+2017-01-31,Effect of radiation-like solid on small-scale CMB anisotropies,"We compute the CMB angular power spectrum in the presence of a radiation-like
+solid - elastic matter with the same pressure to energy density ratio as
+radiation but with nonzero shear modulus. For the values of shear modulus that
+are close enough to zero, so that the effect of the solid on large-scale
+anisotropies remains within cosmic variance, we find that there is an
+observable effect of the solid on small-scale anisotropies.",1701.09061v2
+2017-02-06,Polarimetric analysis of stress anisotropy in nanomechanical silicon nitride resonators,"We realise a circular gray-field polariscope to image stress-induced
+birefringence in thin (submicron thick) silicon nitride (SiN) membranes and
+strings. This enables quantitative mapping of the orientation of principal
+stresses and stress anisotropy, complementary to, and in agreement with, finite
+element modeling (FEM). Furthermore, using a sample with a well known stress
+anisotropy, we extract a new value for the photoelastic (Brewster) coefficient
+of silicon nitride, $C \approx (3.4~\pm~0.1)\times~10^{-6}~\mathrm{MPa}^{-1}$.
+We explore possible applications of the method to analyse and quality-control
+stressed membranes with phononic crystal patterns",1702.01732v1
+2017-04-14,Structure of virtual photon polarization in ultrarelativistic heavy-ion collisions,"Anisotropy in heavy-ion collisions leads to polarization of both direct and
+virtual photons, the latter detected via internal conversion to dileptons
+pairs. Thus measurement of photon polarization probes the anisotropy at all
+stages of collisions. In order to characterize the polarization of virtual
+photons, we derive here the general structure of the photon polarization
+operator, rho^(mu nu), in an anisotropic medium, in terms of the four spectral
+functions, two transverse and one longitudinal, as usual, plus a new spectral
+function that reflects anisotropy in asymmetric collisions; and derive the
+local production rate of dilepton pairs in terms of these four functions.",1704.04526v1
+2017-06-05,Study of the one-way speed of light anisotropy with particle beams,"Concepts of high precision studies of the one-way speed of light anisotropy
+are discussed. The high energy particle beam allows measurement of a one-way
+speed of light anisotropy (SOLA) via analysis of the beam momentum variation
+with sidereal phase without the use of synchronized clocks. High precision beam
+position monitors could provide accurate monitoring of the beam orbit and
+determination of the particle beam momentum with relative accuracy on the level
+of $10^{-10}$, which corresponds to a limit on SOLA of $10^{-18}$ with existing
+storage rings. A few additional versions of the experiment are also presented.",1706.01267v1
+2017-07-19,The fully kinetic Biermann battery and associated generation of pressure anisotropy,"The dynamical evolution of a fully kinetic, collisionless system with imposed
+background density and temperature gradients is investigated analytically. The
+temperature gradient leads to the generation of temperature anisotropy, with
+the temperature along the gradient becoming larger than that in the direction
+perpendicular to it. This causes the system to become unstable to pressure
+anisotropy driven instabilities, dominantly to electron Weibel. When both
+density and temperature gradients are present and non-parallel to each other,
+we obtain a Biermann-like linear in time magnetic field growth. Accompanying
+particle in cell numerical simulations are shown to confirm our analytical
+results.",1707.06069v1
+2017-08-05,Phase field modelling of precipitate morphologies in systems with tetragonal interfacial free energy anisotropy,"A wide variety of morphologies arise due to the tetragonal anisotropy in
+interfacial free energy. In this paper, we report on a family of Extended
+Cahn-Hilliard (ECH) models for incorporating tetragonal anisotropy in
+interfacial free energy. We list the non-zero and independent parameters that
+are introduced in our model and list the constraints on them. For appropriate
+choice of these parameters, our model can produce a many of the morphologies
+seen in tetragonal systems such as di-pyramids, rods, plates and their
+truncated variants. We analyse these morphologies and show that they indeed are
+equilibrium morphologies consistent with the Wulff construction.",1708.01712v1
+2017-09-25,Dynamics of elastically strained islands in presence of an anisotropic surface energy,"The equilibrium solutions and coarsening dynamics of strained semi-conductor
+islands are investigated analytically and numerically. We develop an analytical
+model to study the effect of surface energy anisotropy on the dynamics
+coarsening of islands. We propose a simple model to explain the effect of this
+anisotropy on the coarsening time. We find that the anisotropy slows down the
+coarsening. This effect is rationalised using a quasi-analytical description of
+the island profile.",1709.08570v1
+2017-10-30,Tunneling Devices with Perpendicular Magnetic Anisotropy Electrodes on Atomically Thin van der Waals Heterostructures,"We report the fabrication of perpendicular ferromagnetic electrodes for
+tunneling devices consist of van der Waals heterostructure. We found MgO/Co/Pt
+films on Hexagonal BN shows perpendicular magnetic anisotropy (PMA) with the
+easy axis perpendicular to the substrate. Vacuum annealing enhances the
+perpendicular anisotropy. The easy axis along the perpendicular direction
+persists up to room temperature with the Pt layer thickness ranges from 1.5 to
+5 nm. We employed the PMA electrodes to construct tunneling devices on graphene
+and monolayer WSe2, where spin injection characteristics and field effect
+transistor behavior were demonstrated without strong Schottky barrier
+formation.",1710.10743v1
+2017-12-15,Effect of the Canting of Local Anisotropy Axes on Ground-State Properties of a Ferrimagnetic Chain with Regularly Alternating Ising and Heisenberg Spins,"The effect of the canting of local anisotropy axes on the ground-state phase
+diagram and magnetization of a ferrimagnetic chain with regularly alternating
+Ising and Heisenberg spins is exactly examined in an arbitrarily oriented
+magnetic field. It is shown that individual contributions of Ising and
+Heisenberg spins to the total magnetization basically depend on the spatial
+orientation of the magnetic field and the canting angle between two different
+local anisotropy axes of the Ising spins.",1712.05622v1
+2018-02-13,Integrable Toda system as a quantum approximation to the anisotropy of Mixmaster,"We present a regularisation approach to the study of the quantum dynamics of
+the Mixmaster universe which allows to approximate the anisotropy potential
+with the explicitly integrable periodic 3-particle Toda system. This approach
+is based on a covariant Weyl-Heisenberg integral quantization. Such a procedure
+naturally amplifies the dynamical role of the underlying Toda system by
+smoothing out the three canyons of the anisotropy potential. Since the
+respective eigenfunctions can be explicitly constructed, our finding paves the
+way to a novel perturbative approach to the quantum Mixmaster dynamics.",1802.04662v2
+2018-07-26,Are 10 EeV cosmic rays extragalactic? Theory of cosmic ray diffusion at high energy,"Auger Collaboration has reported a large-scale anisotropy in the arrival
+directions of cosmic rays above 8 EeV. The dipole direction, at 125$^\circ$
+from the Galactic center, is taken as an indication of an extragalactic origin
+of these cosmic rays. We show, both theoretically and by direct numerical
+simulations, that this is not necessarily true. Intermediate mass nuclei
+originating in the Galaxy and diffusing in the Galactic magnetic field can have
+a dipole anisotropy pointing away from the Galactic center. Our theory predicts
+a quadrupole anisotropy of the same order of magnitude as the dipole.",1808.00041v1
+2018-08-24,Hunting for Statistical Anisotropy in Tensor Modes with B-mode Observations,"We investigate a possibility of constraining statistical anisotropies of the
+primordial tensor perturbations by using future observations for the Cosmic
+Microwave Background (CMB) B-mode polarization. By parameterizing a
+statistically-anisotropic tensor power spectrum as $P_h ({\boldsymbol{k}}) =
+P_h (k) \sum_n g_n \cos^n \theta_{\boldsymbol{k}}$, where
+$\theta_{\boldsymbol{k}}$ is an angle of the direction of
+$\hat{k}={\boldsymbol{k}}/k$ from a preferred direction, we find that it would
+be possible for future B-mode observations such as CMB-S4 to detect the tensor
+statistical anisotropy at the level of $g_n \sim {\mathcal O} (0.1)$.",1808.08044v1
+2018-09-05,Spiral plane flops in frustrated helimagnets in external magnetic field,"We discuss theoretically frustrated Heisenberg spiral magnets in magnetic
+field $\bf H$. We demonstrate that small anisotropic spin interactions
+(single-ion biaxial anisotropy or dipolar forces) select the plane in which
+spins rotate (spiral plane) and can lead to the spiral plane flop upon in-plane
+field increasing. Expressions for the critical fields $H_{flop}$ are derived.
+It is shown that measuring of $H_{flop}$ is an efficient and simple method of
+quantifying the anisotropy in the system (as the measurement of spin-flop
+fields in collinear magnets with axial anisotropy). Corresponding recent
+experiments are considered in spiral magnets some of which are multiferroics of
+spin origin.",1809.01680v1
+2018-11-02,New magnetic states in nanorings created by anisotropy gradients,"Magnetic nanorings have been widely studied due to their potential
+applications in spintronic and magnonic devices. In this work, by means of
+analytical calculations and micromagnetic simulations we have analyzed the
+magnetic energy of nanorings with variable anisotropy along their radius. Four
+magnetic states, including two new magnetic configurations, here called meron
+and knot-like states, are considered, looking to the relative lower energy
+states as a function of anisotropy. Phase diagrams with this states are
+presented.",1811.01069v1
+2018-11-06,Anisotropic diffusion and the cosmic ray anisotropy,"We argue that the diffusion of cosmic rays in the Galactic magnetic field has
+to be strongly anisotropic. As a result, the number of CR sources contributing
+to the local CR flux is reduced by a factor $\sim 200$. The CR density is
+therefore less smooth, and the contribution of individual sources to the CR
+dipole anisotropy becomes more prominent. In the case of anisotropic diffusion,
+the observed plateau in the CR dipole anisotropy around 2-20 TeV can be
+explained by a 2-3 Myr old CR source which dominates the local CR flux in this
+energy range.",1811.02419v1
+2018-11-20,The Dipole Anisotropy of Galactic Cosmic Rays,"The arrival directions of Galactic cosmic rays exhibit anisotropies up to the
+level of one per-mille over various angular scales. Recent observations of
+TeV-PeV cosmic rays show that the dipole anisotropy has a strong energy
+dependence with a phase-flip around 100 TeV. We argue that this behavior can be
+well understood by the combination of various effects: the anisotropic
+diffusion of cosmic rays, the presence of nearby sources, the Compton-Getting
+effect from our relative motion and the reconstruction bias of ground-based
+observatories.",1811.08136v1
+2018-11-30,Giant superconducting proximity effect on spintronic anisotropy,"We investigate theoretically the interplay of proximity effects due to the
+presence of a superconductor and normal ferromagnetic leads on the formation of
+the spintronic quadrupolar exchange field in a large-spin molecule. We show
+that the spintronic anisotropy can be enhanced by a few orders of magnitude,
+and tuned by changing the strength of coupling to the superconductor.
+Especially large anisotropy is generated in the vicinity of the charge parity
+changing transition of the molecule. We also provide predictions of measurable
+spectral properties being the hallmarks of these phenomena.",1811.12733v2
+2018-12-17,Symmetry and polarity of the voltage-controlled magnetic anisotropy studied by the Anomalous Hall effect,"The voltage-controlled magnetic anisotropy (VCMA) effect in FeB and FeB/W
+films was measured by four independent methods. All measurements are consistent
+and show the same tendency. The coercive field, Hall angle, anisotropy field,
+the magnetization switching time and retention time linearly decrease when the
+gate voltage increases and they linearly increase when the gate voltage
+decreases.",1812.07077v1
+2019-01-01,Puzzles of the cosmic ray anisotropy,"We discuss three of the known puzzles of the cosmic ray anisotropy in the PeV
+and sub-PeV energy region. They are: (1) the so called inverse anisotropy, (2)
+the irregularity in the energy dependence of the amplitude and phase of the
+first harmonic and (3) the contribution of the single source.",1901.00160v4
+2019-01-24,Weak Lensing Effect on CMB in the Presence of a Dipole Anisotropy,"We investigate weak lensing effect on cosmic microwave background (CMB) in
+the presence of dipole anisotropy. The approach of flat-sky approximation is
+considered. We determine the functions $\sigma_0^2$ and $\sigma_2^2$ that
+appear in expressions of the lensed CMB power spectrum in the presence of a
+dipole anisotropy. We determine the correction to B-mode power spectrum which
+is found to be appreciable at low multipoles ($l$). However, the temperature
+and E-mode power spectrum are not altered significantly.",1901.08595v1
+2019-06-24,On relations of anisotropy and linear inhomogeneity using Backus average,"The anisotropy of an equivalent medium resulting from the Backus (1962)
+average is induced by the vertical inhomogeneity among its constituent layers.
+The velocity field of the constituent isotropic layers increases linearly with
+depth, which is assumed to be a good seismological description of sedimentary
+layers Slotnick (1959). We derive an analytical relationship between the
+anisotropy, characterized by the Thomsen (1986) parameters, and the linear
+inhomogeneity parameters, which forms a system of three equations for nine
+unknowns. To obtain well-posedness, we constrain the problem by considering two
+seismological methods applied to field data. We use the results from the two
+methods, for a particular region of interest, to assess the validity of the
+analytical relation.",1906.10196v1
+2019-08-30,Turbulence in a stably stratified fluid: Onset of global anisotropy as a function of the Richardson number,"It is necessary to introduce an external forcing to induce turbulence in a
+stably stratified fluid. The Heisenberg eddy viscosity technique should in this
+case suffice to calculate a space-time averaged quantity like the global
+anisotropy parameter as a function of the Richardson number. We find
+analytically that the anisotropy increases linearly with the Richardson number,
+with a small quadratic correction. A numerical simulation of the complete
+equations shows the linear behaviour.",1908.11767v1
+2019-11-12,On the future of solutions to the massless Einstein-Vlasov system in a Bianchi I cosmology,"We show that massless solutions to the Einstein-Vlasov system in a Bianchi I
+space-time with small anisotropy, i.e. small shear and small trace-free part of
+the spatial energy momentum tensor, tend to a radiation fluid in an Einstein-de
+Sitter space-time with the anisotropy $\Sigma^a_b\Sigma^b_a$ and $\tilde{w}^i_j
+\tilde{w}^j_i$ decaying as $O(t^{-\frac12})$.",1911.04937v2
+2020-02-05,Spherical harmonic analysis of anisotropies in polarized stochastic gravitational wave background with interferometry experiments,"We study the interferometric observation of intensity and polarization
+anisotropies of a stochastic gravitational wave background (SGWB). We show that
+the observed correlated data is defined in the group manifold of the
+three-dimensional rotation. Explicit correlation between two detectors in the
+interferometry experiments such as LIGO-Virgo and KAGRA is constructed in terms
+of the Wigner D-functions. Our results may provide a tool for constructing data
+pipelines to estimate the power spectra of the SGWB anisotropies.",2002.01606v3
+2020-03-27,Substrate Induced Optical Anisotropy in Monolayer MoS$_2$,"In-plane optical anisotropy has been detected from monolayer MoS$_2$ grown on
+a-plane (11-20) sapphire substrate in the ultraviolet-visible wavelength range.
+Based on the measured optical anisotropy, the energy differences between the
+optical transitions polarized along the ordinary and extraordinary directions
+of the underlying sapphire substrate have been determined. The results
+corroborate comprehensively with the dielectric environment induced
+modification on the electronic band structure and exciton binding energy of
+monolayer MoS$_2$ predicted recently by first principle calculations. The
+output of this study proposes the symmetry as a new degree of freedom for
+dielectric engineering of the two-dimensional materials.",2003.12235v1
+2020-04-07,Critical behavior of the spin-3/2 Blume Capel quantum model with two random transverse single-ion anisotropies,"Using the approach based on the Bogoliubov inequality for free energy, we
+have studied the magnetic properties of the spin-3/2 Blume-Capel quantum model
+in the presence of the random transverse single-ion anisotropy (RTSIA). By
+analyzis of the phase diagrams in $\tau \times \varphi_{x} $, $m \times
+\varphi_{x}$ and $m \times \tau$ plans, we have obtained information about how
+the presence of anisotropy affects the properties of the system. We have shown
+that the RTSIA is responsible for changing the topology of the phase diagrams,
+compared to the pure model, leading to the appearance tricritical point (TCP).",2004.03527v1
+2020-06-19,Anisotropic generalization of Vaidya-Tikekar superdense star,"We study superdense relativistic stars with anisotropic matter distributions
+with spheroidal spatial hypersurfaces. We propose a methodology to make an
+anisotropic generalization of the Vaidya-Tikekar superdense star model. The
+anisotropic Einstein field equations can be solved in terms of hypergeometric
+functions for our choice of gravitational potential and anisotropy. Particular
+parameter choices allow us to generate models of anisotropic stars in terms of
+elementary functions. Also, isotropic stars can be generated in the limit of
+vanishing anisotropy. In particular, we obtain the well known superdense models
+of Tikekar which are isotropic and have specific spheroidal geometries. The
+impact of anisotropy on the gross physical behaviour of a compact star is
+studied.",2006.12266v1
+2020-10-13,Modeling evolution of composition patterns in a binary surface alloy,"Evolution of composition patterns in the annealed, single-crystal surface
+alloy film is considered in the presence of the spinodal decomposition, the
+compositional stress and the diffusion anisotropy. While the former two effects
+contribute to overall phase separation, the anisotropy, correlated with the
+surface crystallographic orientation, guides the in-plane formation and
+orientation of a pattern. The impacts of the anisotropy parameters on patterns
+are systematically computed for [110], [100], and [111]-oriented fcc cubic
+alloy surfaces.",2010.06838v1
+2021-03-29,Atomistic modelling of frictional anisotropy of palladium nanoparticles on graphene,"This article is a continuation of our previous studies of the frictional
+anisotropy of metal nanoparticles on the surface of a graphene substrate for
+other temperature conditions. The friction force acting on palladium
+nanoparticles on a graphene sheet in various lateral directions is investigated
+using classical molecular dynamics modelling. Anisotropy is studied at high
+sliding speeds of nanoparticles consisting of 10000 atoms on the surface of
+graphene. The effect of incommensurability and short-range order of the contact
+surfaces of nanoparticles, as well as the graphene deformation lead to the
+absence of an expressed angular dependence of the friction force.",2103.15494v1
+2021-05-03,Anisotropy-Exchange Resonance as a Mechanism for Entangled State Switching,"We explore the three-particle spin model of an $S_{1}=\frac{1}{2}$ particle
+(e.g. a stationary electron) interacting with two spin-coupled $S_{\text{2,3}}$
+particles with exchange coupling and magnetic anisotropy. We find that in the
+case of $S_{2,3}=1$ particles, the coupled particle entanglement states can be
+prepared, controlled, and read by the $S_{1}$ particle. We also find that for
+particular resonance conditions of the magnetic anisotropy strength $D$ and
+exchange coupling strength $J$, the entanglement state switching behavior is
+maximized and is robust against a range of anisotropic application of the
+exchange coupling.",2105.01126v1
+2021-09-10,An Efficient High-order Numerical Solver for Diffusion Equations with Strong Anisotropy,"In this paper, we present an interior penalty discontinuous Galerkin finite
+element scheme for solving diffusion problems with strong anisotropy arising in
+magnetized plasmas for fusion applications. We demonstrate the accuracy
+produced by the high-order scheme and develop an efficient preconditioning
+technique to solve the corresponding linear system, which is robust to the mesh
+size and anisotropy of the problem. Several numerical tests are provided to
+validate the accuracy and efficiency of the proposed algorithm.",2109.05085v1
+2021-10-05,Jet-temperature anisotropy revealed through high-$p_\perp$ data,"We explore to what extent, and how, high-$p_\perp$ data and predictions
+reflect the shape and anisotropy of the QCD medium formed in ultrarelativistic
+heavy-ion collisions. To this end, we use our recently developed DREENA-A
+framework, which can accommodate any temperature profile within the dynamical
+energy loss formalism. We show that the ratio of high-$p_\perp$ $v_2$ and
+$(1-R_{AA})$ predictions reaches a well-defined saturation value, which is
+directly proportional to the time-averaged anisotropy of the evolving QGP, as
+seen by the jets.",2110.02029v2
+2022-05-16,Magnetic neutron scattering from spherical nanoparticles with Neel surface anisotropy: Atomistic simulations,"We consider a dilute ensemble of randomly-oriented noninteracting spherical
+nanomagnets and investigate its magnetization structure and ensuing
+neutron-scattering response by numerically solving the Landau-Lifshitz
+equation. Taking into account the isotropic exchange interaction, an external
+magnetic field, a uniaxial magnetic anisotropy for the particle core, and in
+particular the Neel surface anisotropy, we compute the magnetic small-angle
+neutron scattering cross section and pair-distance distribution function from
+the obtained equilibrium spin structures. The numerical results are compared to
+the well-known analytical expressions for uniformly magnetized particles and
+provide guidance to the experimentalist. Moreover, the effect of a
+particle-size distribution function is modeled.",2205.07552v1
+2022-05-16,Feedback of non-local $d_{xy}$ nematicity on the magnetic anisotropy in FeSe,"We analyze theoretically the magnetic anisotropy in the nematic phase of FeSe
+by computing the spin and the orbital susceptibilities from the microscopic
+multiorbital model. In particular, we take into account both the $xz/yz$ and
+the recently proposed non-local $xy$ nematic ordering and show that the latter
+one could play a crucial role in reproducing the experimentally-measured
+temperature dependence of the magnetic anisotropy. This provides a direct
+fingerprint of the different nematic scenarios on the magnetic properties of
+FeSe.",2205.07718v1
+2022-06-15,Optimization of the anisotropic Cheeger constant with respect to the anisotropy,"Given an open, bounded set $\Omega$ in $\mathbb{R}^N$, we consider the
+minimization of the anisotropic Cheeger constant $h_K(\Omega)$ with respect to
+the anisotropy $K$, under a volume constraint on the associated unit ball. In
+the planar case, under the assumption that $K$ is a convex, centrally symmetric
+body, we prove the existence of a minimizer. Moreover, if $\Omega$ is a ball,
+we show that the optimal anisotropy $K$ is not a ball and that, among all
+regular polygons, the square provides the minimal value.",2206.07436v2
+2022-10-16,On the angular anisotropy of the randomly-averaged magnetic neutron scattering cross section of nanoparticles,"We calculate the magnetic SANS cross section of dilute ensembles of uniformly
+magnetized and randomly-oriented Stoner-Wohlfarth particles using the
+Landau-Lifshitz equation. The focus of our study is on the angular anisotropy
+of the magnetic SANS signal as it can be seen on a two-dimensional
+position-sensitive detector. Depending on the symmetry of the magnetic
+anisotropy of the particles (e.g. uniaxial, cubic), an anisotropic magnetic
+SANS pattern may result, even in the demagnetized state or at the coercive
+field. The case of inhomogeneously magnetized particles and the effects of a
+particle-size distribution and interparticle correlations are discussed.",2210.08406v1
+2022-10-30,Controlling magnetic anisotropy in amplitude expansion of phase field crystal model,"The amplitude expansion for a magnetic phase-field-crystal (magnetic APFC)
+model enables a convenient coarse-grained description of crystalline structures
+under the influence of magnetic fields. Considering higher-order magnetic
+coupling terms, we demonstrate the possibility of tuning the magnetic
+anisotropy in these models. This allows for reproducing the easy and hard
+direction of magnetization. Such a result can be achieved without increasing
+the computational cost, enabling simulations of the manipulation of dislocation
+networks and microstructures in ferromagnetic materials. As a demonstration, we
+report on the simulation of the shrinkage of a spherical grain with the
+magnetic anisotropy of Fe.",2210.16855v1
+2022-11-24,Effects of target anisotropy on harmonic measure and mean first-passage time,"In this paper, we investigate the influence of target anisotropy on two
+characteristics of diffusion-controlled reactions: harmonic measure density and
+mean first-passage time. First, we compute the volume-averaged harmonic measure
+density on prolate and oblate spheroidal targets inside a confining domain in
+three dimensions. This allows us to quantify the uniformity of this density in
+the small target limit. Second, we derive an explicit expression of the mean
+first-passage time to such targets and analyze the effect of anisotropy. In
+particular, we illustrate the accuracy of the capacitance approximation for
+small targets.",2212.00011v2
+2023-06-08,Magnetic anisotropy of superconducting transition in S/AF heterostructures with spin-orbit coupling,"The influence of Rashba spin-orbit coupling (SOC) on superconducting
+correlations in thin-film superconductor/antiferromagnet (S/AF) structures with
+compensated interfaces is studied. A unique effect of anisotropic enhancement
+of proximity-induced triplet correlations by the SOC is predicted. It manifests
+itself in the anisotropy of the superconducting critical temperature Tc with
+respect to orientation of the Neel vector relative to the S/AF interface, which
+is opposite to the behaviour of Tc in superconductor/ferromagnet structures. We
+show that the anisotropy is controlled by the chemical potential of the
+superconductor and, therefore, can be adjusted in (quasi)2D structures.",2306.05055v1
+2023-08-14,Probing extreme astrophysical accelerators through neutrino anisotropy,"We present the extent to which anisotropies in the ultrahigh energy neutrino
+sky can probe the distribution of extreme astrophysical accelerators in the
+universe. In this talk, we discuss the origin of an anisotropic neutrino sky
+and show how observers can use this anisotropy to measure the evolution of
+ultrahigh energy neutrino sources - and therefore, the sources of ultrahigh
+energy cosmic rays - for the very first time.",2308.07211v2
+2023-08-30,Neutrino anisotropy as a probe of extreme astrophysical accelerators,"We consider how the cutoff of the ultrahigh energy neutrino spectrum
+introduces an effective neutrino horizon, allowing for future neutrino
+detectors to measure an anisotropy in neutrino arrival directions driven by the
+local large-scale structure. We show that measurement of the level of this
+anisotropy along with features of the neutrino spectrum will allow for a
+measurement of the evolution of ultrahigh energy neutrino sources, which are
+expected to also be the sources of ultrahigh energy cosmic rays.",2308.16225v1
+2023-10-03,Analysis of Local Anisotropy Fluctuations in Compact Objects,"Mathematical modeling within the framework of the general theory of
+relativity has been used to explain the behavior and structure of massive
+objects as neutron stars, quasars, black holes, pulsars and white dwarfs and
+requires finding the exact solutions of the Einstein-Maxwell system. In this
+paper we study the effects induced by fluctuations of local anisotropy in a new
+family of anisotropic solutions depending on a parameter, with a specific value
+that provides a radial pressure having the same functional dependence on the
+radial coordinate as the Schwarzschild solution. It is shown the effect the
+functional dependence on the radial coordinate has in the occurrence of
+cracking within the sphere when anisotropy fluctuations are allowed.",2310.01730v1
+2023-12-03,Thermally Averaged Magnetic Anisotropy Tensors via Machine Learning Based on Gaussian Moments,"We propose a machine learning method to model molecular tensorial quantities,
+namely the magnetic anisotropy tensor, based on the Gaussian-moment
+neural-network approach. We demonstrate that the proposed methodology can
+achieve an accuracy of 0.3--0.4 cm$^{-1}$ and has excellent generalization
+capability for out-of-sample configurations. Moreover, in combination with
+machine-learned interatomic potential energies based on Gaussian moments, our
+approach can be applied to study the dynamic behavior of magnetic anisotropy
+tensors and provide a unique insight into spin-phonon relaxation.",2312.01415v1
+2023-12-18,Peculiarities of spin-orbit interaction systematically measured in FeCoB nanomagnets,"This study introduces a method to measure strength of spin-orbit interaction
+(SO) in a nanomagnet, investigating fundamental phenomena governing magnetic
+anisotropy. The method explores the fundamental property of SO in its linear
+proportionality to the external magnetic field, a relationship validated
+through experimental observation. Systematic study of SO in FeCoB nanomagnets
+reveals distinct SO behaviors in bulk and at an interface, its substantial
+disparities in single- and multi-layer nanomagnets, intriguing periodic
+oscillations in SO strength, and the systematic relationship between SO
+strength, demagnetization field, and magnetic anisotropy based on surface
+imperfections. These findings provide crucial insights into diverse spin-orbit
+interaction behaviors, crucial for understanding and optimizing magnetic
+anisotropy and nanomagnet properties.",2312.11056v1
+1993-12-08,Large-Angle Cosmic Microwave Background Anisotropies in an Open Universe,"If the Universe is open, scales larger than the curvature scale may be probed
+by large-angle fluctuations in the cosmic microwave background (CMB). We
+consider primordial adiabatic perturbations and discuss power spectra that are
+power laws in volume, wavelength, and eigenvalue of the Laplace operator. The
+resulting large-angle anisotropies of the CMB are computed. The amplitude
+generally increases as $\Omega$ is decreased, but decreases as $h$ is
+increased. Interestingly enough, for all three ansatzes, anisotropies on
+angular scales larger than the curvature scale are suppressed relative to the
+anisotropies on scales smaller than the curvature scale. Models with
+$0.2<\Omega h<0.3$ appear compatible with CMB fluctuations detected by COBE and
+Tenerife and with the amplitude and spectrum of fluctuations of galaxy counts
+in galaxy surveys. COBE normalization for these models yields $\sigma_8\simeq
+0.5-0.7$. Models with smaller values of $\Omega h$ when normalized to COBE
+require bias factors in excess of 2 to be compatible with the observed galaxy
+counts on the $8/h$ Mpc scale. Requiring that the age of the universe exceed 10
+Gyr implies that $\Omega>0.25$, while requiring that the age exceed 13 Gyr
+implies that $\Omega>0.35$. Unlike in the flat-Universe case where the
+anisotropy comes only from the last-scattering term in the Sachs-Wolfe formula,
+large-angle anisotropies come primarily from the decay of potential
+fluctuations at $z<1/\Omega$. Thus, if the Universe is open, COBE has been
+detecting fluctuations produced at moderate redshift rather than at $z\sim
+1300$.",9312017v1
+1995-10-04,Cosmic Microwave Background Anisotropies from the Rees-Sciama Effect in $Ω_{0} \le 1$ Universes,"We investigate the imprint of nonlinear matter condensations on the Cosmic
+Microwave Background (CMB) in $\Omega_{0}<1$ cold dark matter (CDM) model
+universes. We consider simulation domains ranging from $120h^{-1}$ Mpc to
+$360h^{-1}$ Mpc in size. We concentrate on the secondary temperature
+anisotropies induced by time varying gravitational potentials occurring after
+decoupling. Specifically, we investigate the importance of the Rees-Sciama
+effect due to: (1) intrinsic changes in the gravitational potential of forming,
+nonlinear structures, (2) proper motion of nonlinear structures, and (3) late
+time decay of gravitational potential perturbations in open universes. CMB
+temperature anisotropies are obtained by numerically evolving matter
+inhomogeneities and CMB photons from an early, linear epoch ($z=100$) to the
+present, nonlinear epoch $(z=0)$. We test the dependence and relative
+importance of these secondary temperature anisotropies as a function of the
+scale of the underlying matter (voids, superclusters) and as a function of
+$\Omega_{0}$. The results of the $\Omega_{0}<1$ models are compared to a
+similarly executed $\Omega_{0}=1.0$ simulation. We find that in low density
+models all three sources of anisotropy could be relevant and reach levels of
+$\Delta T/T \sim 10^{-6}$. In particular, we find that for $\Omega_{0}<1$ at
+large scales, secondary temperature anisotropies are dominated by the decaying
+potential.",9510019v1
+1996-10-30,"Stellar systems following the R^{1/m} luminosity law. II Anisotropy, velocity profiles, and the FP of elliptical galaxies","We study the dynamical properties of spherical galaxies with surface
+luminosity profile described by the R^{1/m}-law, in which a variable degree of
+orbital anisotropy is allowed. The parameter m for the present models covers
+the range [1,10]. For these models we study the self-consistently generated
+phase-space distribution function (DF), and we derive - as a function of m -
+the minimum value of the anisotropy radius for the model consistency (i.e., in
+order to have a nowhere negative DF). Then we study the region in the parameter
+space where the R^{1/m} models are likely to be stable against radial-orbit
+instability, and we compare its size with that of the larger region
+corresponding to the consistency requirement. For stable anisotropic models the
+spatial and projected velocity dispersion profiles are obtained solving the
+Jeans equation, and compared to those of the globally isotropic case, already
+discussed in Paper I. The relevance of the results in connection with the
+Fundamental Plane (FP) of elliptical galaxies is pointed out: the effect on the
+projected velocity dispersion due to the maximum orbital anisotropy allowed by
+the stability requirement is well within the FP thickness, and so no
+fine-tuning for anisotropy is required. Finally, the Velocity Profiles are
+constructed as function of the projected radius and for various degrees of
+anisotropy, and their deviations from a gaussian discussed.",9610251v1
+1997-08-02,Skewness in the Cosmic Microwave Background Anisotropy from Inflationary Gravity Wave Background,"In the context of inflationary scenarios, the observed large angle anisotropy
+of the Cosmic Microwave Background (CMB) temperature is believed to probe the
+primordial metric perturbations from inflation. Although the perturbations from
+inflation are expected to be gaussian random fields, there remains the
+possibility that nonlinear processes at later epochs induce ``secondary''
+non-gaussian features in the corresponding CMB anisotropy maps. The
+non-gaussianity induced by nonlinear gravitational instability of scalar
+(density) perturbations has been investigated in existing literature. In this
+paper, we highlight another source of non-gaussianity arising out of higher
+order scattering of CMB photons off the metric perturbations. We provide a
+simple and elegant formalism for deriving the CMB temperature fluctuations
+arising due to the Sachs-Wolfe effect beyond the linear order. In particular,
+we derive the expression for the second order CMB temperature fluctuations. The
+multiple scattering effect pointed out in this paper leads to the possibility
+that tensor metric perturbation, i.e., gravity waves (GW) which do not exhibit
+gravitational instability can still contribute to the skewness in the CMB
+anisotropy maps. We find that in a flat $\Omega =1$ universe, the skewness in
+CMB contributed by gravity waves via multiple scattering effect is comparable
+to that from the gravitational instability of scalar perturbations for equal
+contribution of the gravity waves and scalar perturbations to the total rms CMB
+anisotropy. The secondary skewness is found to be smaller than the cosmic
+variance leading to the conclusion that inflationary scenarios do predict that
+the observed CMB anisotropy should be statistically consistent with a gaussian
+random distribution.",9708015v1
+1999-06-25,"Projection, Spatial Correlations, and Anisotropies in a Large and Complete Sample of Abell Clusters","An analysis of R >= 1 Abell clusters is presented for samples containing
+recent redshifts from the MX Northern Abell Cluster Survey. The newly obtained
+redshifts from the MX Survey as well as those from the ESO Nearby Abell Cluster
+Survey (ENACS) provide the necessary data for the largest magnitude-limited
+correlation analysis of rich clusters in the entire sky (excluding the galactic
+plane) to date. We find 19.4 <= r_0 <= 23.3 h^-1Mpc, -1.92 <= gamma <= -1.83
+for four different subsets of Abell/ACO clusters, including a large sample
+(N=104) of cD clusters. We have used this dataset to look for line-of-sight
+anisotropies within the Abell/ACO catalogs. We show that the strong
+anisotropies present in previously studied Abell cluster datasets are not
+present in our R >= 1 samples. There are, however, indications of residual
+anisotropies which we show are the result of two elongated superclusters, Ursa
+Majoris and Corona Borealis, whose axes lie near the line-of-sight. After
+rotating these superclusters so that their semi-major axes are prependicular to
+the line-of-sight, we find no anisotropies as indicated by the correlation
+function. The amplitude and slope of the two-point correlation function remain
+the same before and after these rotations. We also remove a subset of R = 1
+Abell/ACO clusters that show sizable foreground/background galaxy contamination
+and again find no change in the amplitude or slope of the correlation function.
+We conclude that the correlation length of R >= 1 Abell clusters is not
+artificially enhanced by line-of-sight anisotropies.",9906414v1
+2001-02-23,Gaussianity of Degree-Scale Cosmic Microwave Background Anisotropy Observations,"We present results from a first test of the Gaussianity of degree-scale
+cosmic microwave background (CMB) anisotropy. We investigate Gaussianity of the
+CMB anisotropy by studying the topology of CMB anisotropy maps from the QMAP
+and Saskatoon experiments. We also study the QMASK map, a combination map of
+the QMAP and Saskatoon data. We measure the genus from noise-suppressed
+Wiener-filtered maps at an angular scale of about 1.5 degrees. To test the
+Gaussianity of the observed anisotropy, we compare these results to those
+derived from a collection of simulated maps for each experiment in a Gaussian
+spatially-flat cosmological constant dominated cold dark matter model. The
+genus-threshold level relations of the QMAP and Saskatoon maps are consistent
+with Gaussianity. While the combination QMASK map has a mildly non-Gaussian
+genus curve which is not a consequence of known foreground contamination, this
+result is not statistically significant at the 2 sigma level. These results
+extend previous upper limits on the non-Gaussianity of the large angular scale
+(> 10 degrees) CMB anisotropy (measured by the COBE DMR experiment) down to
+degree angular scales.",0102406v2
+2002-10-22,Microwave anisotropies from the Galactic halo,"Models in which a large fraction of the Galactic dark matter takes the form
+of cold gas clouds imply that there is thermal microwave emission from the
+Galactic dark halo. Such models can therefore be directly constrained by data
+on the microwave sky, and in particular the very sensitive observations of
+microwave anisotropies which are now being made. To this end we have computed
+the anisotropy power-spectrum expected for a Galactic dark halo made of cold,
+dense gas clouds, including the effects of clustering with a CDM-like mass
+spectrum of mini-halo substructure. The power-spectrum displays two peaks: one,
+at l~50, is the Poisson noise for the mini-halos, and the second, much larger
+and at much higher l, is the Poisson noise of the individual clouds. Because it
+appears on small (milli-arcsecond) angular scales, where the instrumental
+sensitivity is inevitably very poor, the latter signal is not directly
+detectable. By contrast, clusters of cold gas clouds may contribute
+significantly to the observed anisotropies if their emission has a grey-body
+spectrum. In this case the peak fluctuation, at l~50, amounts to 4/|sin b|
+micro-K in the Rayleigh-Jeans limit, and is the dominant Galactic foreground
+between 40 and 80 GHz. It will be possible to constrain this foreground
+component using low-latitude data from the MAP satellite, providing that its
+spectrum conforms to a grey-body. If the spectrum is ``dusty'' there will be
+relatively little power at frequencies below the thermal peak, and in this case
+the predicted anisotropies are shown to be negligible.",0210483v2
+2005-02-28,Cosmic 21-cm Delensing of Microwave Background Polarization and the Minimum Detectable Energy Scale of Inflation,"The curl (B) modes of cosmic microwave background (CMB) polarization
+anisotropies are a unique probe of the primordial background of inflationary
+gravitational waves (IGWs). Unfortunately, the B-mode polarization anisotropies
+generated by gravitational waves at recombination are confused with those
+generated by the mixing of gradient-mode (E-mode) and B-mode polarization
+anisotropies as CMB photons propagate through the Universe and are
+gravitationally lensed. We describe here a method for delensing CMB
+polarization anisotropies using observations of anisotropies in the cosmic
+21-cm radiation emitted or absorbed by neutral hydrogen atoms at redshifts 10
+to 200. While the detection of cosmic 21-cm anisotropies at high resolution is
+challenging, a combined study with a relatively low-resolution (but
+high-sensitivity) CMB polarization experiment could probe inflationary energy
+scales well below the Grand Unified Theory (GUT) scale of 10^{16} GeV --
+constraining models with energy scales below 10^{15} GeV (the detectable limit
+derived from CMB observations alone). The ultimate theoretical limit to the
+detectable inflationary energy scale via this method may be as low as 3 \times
+10^{14} GeV.",0502549v1
+2007-03-22,Anisotropy Studies of the Unresolved Far-infrared Background,"Dusty, starforming galaxies and active galactic nuclei that contribute to the
+integrated background intensity at far-infrared wavelengths trace the
+large-scale structure. Below the point source detection limit, correlations in
+the large-scale structure lead to clustered anisotropies in the unresolved
+component of the far-infrared background (FIRB). The angular power spectrum of
+the FIRB anisotropies could be measured in large-area surveys with the Spectral
+and Photometric Imaging Receiver (SPIRE) on the upcoming Herschel observatory.
+To study statistical properties of these anisotropies, the confusion from
+foreground Galactic dust emission needs to be reduced even in the ``cleanest''
+regions of the sky.The multi-frequency coverage of SPIRE allows the foreground
+dust to be partly separated from the extragalactic background composed of dusty
+starforming galaxies as well as faint normal galaxies. The separation improves
+for fields with sizes greater than a few hundred square degrees and when
+combined with Planck data. We show that an area of about $\sim$ 400 degrees$^2$
+observed for about 1000 hours with Herschel-SPIRE and complemented by Planck
+provides maximal information on the anisotropy power spectrum. We discuss the
+scientific studies that can be done with measurements of the unresolved FIRB
+anisotropies including a determination of the large scale bias and the
+small-scale halo occupation distribution of FIRB sources with fluxes below the
+point-source detection level.",0703592v2
+1995-07-17,Magneto-Conductance Anisotropy and Interference Effects in Variable Range Hopping,"We investigate the magneto-conductance (MC) anisotropy in the variable range
+hopping regime, caused by quantum interference effects in three dimensions.
+When no spin-orbit scattering is included, there is an increase in the
+localization length (as in two dimensions), producing a large positive MC. By
+contrast, with spin-orbit scattering present, there is no change in the
+localization length, and only a small increase in the overall tunneling
+amplitude. The numerical data for small magnetic fields $B$, and hopping
+lengths $t$, can be collapsed by using scaling variables $B_\perp t^{3/2}$, and
+$B_\parallel t$ in the perpendicular and parallel field orientations
+respectively. This is in agreement with the flux through a `cigar'--shaped
+region with a diffusive transverse dimension proportional to $\sqrt{t}$. If a
+single hop dominates the conductivity of the sample, this leads to a
+characteristic orientational `finger print' for the MC anisotropy. However, we
+estimate that many hops contribute to conductivity of typical samples, and thus
+averaging over critical hop orientations renders the bulk sample isotropic, as
+seen experimentally. Anisotropy appears for thin films, when the length of the
+hop is comparable to the thickness. The hops are then restricted to align with
+the sample plane, leading to different MC behaviors parallel and perpendicular
+to it, even after averaging over many hops. We predict the variations of such
+anisotropy with both the hop size and the magnetic field strength. An
+orientational bias produced by strong electric fields will also lead to MC
+anisotropy.",9507066v1
+2002-02-26,Increasing Superconducting Tc's by a Factor of 1000 with StripeLike Hopping Anisotropies,"We have studied the enhancement of the superconducting transition
+temperature, Tc, in a t-J-U model of electrons moving on a square lattice in
+which anisotropic electronic hopping is introduced. The inclusion of such
+hopping mimics, in a approximate fashion, a potentially important
+characteristic of materials possessing stripelike charge and spin correlations.
+For this model we have calculated Tc for singlet pairing using the non
+self-consistent Thouless criterion, and find a dramatic enhancement of Tc
+induced by hopping anisotropies. Further, the maximum increase in Tc is
+obtained when the system is pushed towards the extreme anisotropy limit, that
+is, when the hopping of electrons is confined to occur in 1+0^+ dimensions. We
+demonstrate that in this limit the increase in Tc, with respect to the
+isotropic system, can be of the order of 1000. We have also determined that in
+the extreme anisotropy limit the superconducting gap is an equal mixture of s
+and d pairing symmetries (two choices of such a combination being s + d and s +
+id) owing to the reduced (square to rectangular) symmetry of the system in the
+presence of hopping anisotropies. Thus, the presence of d-wave superconducting
+features in materials whose symmetry is very different from that of a
+two-dimensional square lattice, with the anisotropy produced by the appearance
+of stripes, is not unexpected.",0202478v1
+2003-05-29,Magnetic anisotropy and magnetoresistance of sputtered [(FeTaN)/(TaN)](n) multilayers,"We studied the in-plane magnetic anisotropy of rf (radio frequency) sputtered
+[(FeTaN)/(TaN)](n) multilayers synthesized on Si substrates. In the multilayers
+where n=5, the FeTaN thickness is fixed at 30 nm and the thickness of TaN,
+t(TaN), is varied from 0 to 6.0 nm, we observed a clear trend that, with
+increasing t(TaN), the values of coercivity, grain size, and amplitude of
+maximum magnetoresistance (MR) of the samples all decrease first and then
+increase after reaching a minimum when t(TaN) is around 2.0-4.0 nm. This trend
+is also associated with an evolution of in-plane magnetic anisotropy, where the
+multilayers change from uniaxial anisotropy to biaxial at t(TaN) around 4.0 nm
+and above. We attribute the phenomena to the interlayer coupling effect of
+FeTaN films as a function of the coupling layer (TaN) thickness, rather than to
+the thickness dependence observed in single-layered FeTaN films, where the
+direction of easy axis switches 90degrees when the film is thicker than 300 nm.
+The in-plane anisotropy of the [(FeTaN)/(TaN)](n) multilayers also shows signs
+of oscillation when the number of coupling layers varies. The MR effects
+observed are mainly due to anisotropy MR (AMR), while the grain size and
+exchange coupling may also contribute to the change of maximum MR ratios in the
+multilayers with changing t(TaN).",0305687v2
+2004-04-14,Flux melting in BSCCO: Incorporating both electromagnetic and Josephson couplings,"Multilevel Monte Carlo simulations of a BSCCO system are carried out
+including both Josephson as well as electromagnetic couplings for a range of
+anisotropies. A first order melting transition of the flux lattice is seen on
+increasing the temperature and/or the magnetic field. The phase diagram for
+BSCCO is obtained for different values of the anisotropy parameter $\gamma$.
+The best fit to the experimental results of D. Majer {\it et al.} [Phys. Rev.
+Lett. {\bf 75}, 1166 (1995)] is obtained for $\gamma\approx 250$ provided one
+assumes a temperature dependence $\lambda^2(0)/\lambda^2(T)=1-t$ of the
+penetration depth with $t=T/T_c$. Assuming a dependence
+$\lambda^2(0)/\lambda^2(T)=1-t^2$ the best fit is obtained for $ \gamma\approx
+450$. For finite anisotropy the data is shown to collapse on a straight line
+when plotted in dimensionless units which shows that the melting transition can
+be satisfied with a single Lindemann parameter whose value is about 0.3. A
+different scaling applies to the $\gamma=\infty$ case. The energy jump is
+measured across the transition and for large values of $\gamma$ it is found to
+increase with increasing anisotropy and to decrease with increasing magnetic
+field. For infinite anisotropy we see a 2D behavior of flux droplets with a
+transition taking place at a temperature independent of the magnetic field. We
+also show that for smaller values of anisotropy it is reasonable to replace the
+electromagnetic coupling with an in-plane interaction represented by a Bessel
+function of the second kind ($K_0$), thus justifying our claim in a previous
+paper.",0404336v1
+2004-07-07,Many-body Green's function theory of ferromagnetic Heisenberg systems with single-ion anisotropies in more than one direction,"The behaviour of ferromagnetic systems with single-ion anisotropies in more
+than one direction is investigated with many-body Green's function theory
+generalizing earlier work with uniaxial anisotropies only. It turns out to be
+of advantage to construct Green's functions in terms of the spin operators S^x,
+S^y and S^z, instead of the commonly used S^+,S^- and S^z operators. The
+exchange energy terms are decoupled by RPA and the single-ion anisotropy terms
+by a generalization of the Anderson-Callen decoupling. We stress that in the
+derivation of the formalism none of the three spatial axes is special, so that
+one is always able to select a reference direction along which a magnetization
+component is not zero. Analytical expressions are obtained for all three
+components of the magnetization and the expectation values <(S^x)^2>, <(S^y)^2>
+and <(S^z)^2> for any spin quantum number S. The formalism considers both
+in-plane and out-of-plane anisotropies. Numerical calculations illustrate the
+behaviour of the magnetization for 3-dimensional and 2-dimensional systems for
+various parameters. In the 2-dimensional case, the magnetic dipole-dipole
+coupling is included, and a comparison is made between in-plane and
+out-of-plane anisotropies.",0407171v2
+2005-05-23,Anisotropy of incommensurate spin and charge fluctuations in detwinned YBa$_2$Cu$_3$O$_{6+δ}$,"Motivated by a recent neutron scattering experiment on detwinned
+YBa$_2$Cu$_3$O$_{6+\delta}$ superconductor, we examine the frequency and doping
+dependence of the anisotropy in the spin and charge fluctuation arising from
+the coupling between the plane and the chain. Starting from the two-dimensional
+$t$-$t^{'}$-$J$ model and using the random-phase approximation (RPA), we find a
+pronounced anisotropy of the incommensurate (IC) peaks in the spin channel,
+namely the peak intensity at the $(\pi\pm\delta,\pi)$ direction is stronger
+than that at the $(\pi,\pi\pm\delta)$ direction in a wide frequency range from
+$\omega=0.2J$ to the resonance frequency $\omega_r=0.35J$. Above the resonance
+frequency, the IC peaks reemerge. Their intensities shift to the diagonal
+direction and no anisotropy exists along the two diagonal directions. We find
+that this anisotropy is robust with respect to the possible variation of the
+RPA correction factor and to the dopings. The charge fluctuation is also found
+to be incommensurate for all energies considered and peak at $(0,\delta)$ and
+$(\delta,0)$. An anisotropy in its IC peak intensity along the $k_x$ and the
+$k_y$ direction exists, but in sharp contrast to the spin channel, the maximum
+intensity of the IC peak is along the $k_y$ direction. Moreover, the IC peak in
+the charge channel exhibits an upward dispersion, in contrast to the downward
+dispersion below the spin resonance frequency for the spin IC peak. We explain
+these features based on the effect of the plane-chain coupling on the topology
+of the Fermi surface.",0505545v1
+2004-01-16,Anisotropy in Bianchi-type brane cosmologies,"The behavior near the initial singular state of the anisotropy parameter of
+the arbitrary type, homogeneous and anisotropic Bianchi models is considered in
+the framework of the brane world cosmological models. The matter content on the
+brane is assumed to be an isotropic perfect cosmological fluid, obeying a
+barotropic equation of state. To obtain the value of the anisotropy parameter
+at an arbitrary moment an evolution equation is derived, describing the
+dynamics of the anisotropy as a function of the volume scale factor of the
+Universe. The general solution of this equation can be obtained in an exact
+analytical form for the Bianchi I and V types and in a closed form for all
+other homogeneous and anisotropic geometries. The study of the values of the
+anisotropy in the limit of small times shows that for all Bianchi type
+space-times filled with a non-zero pressure cosmological fluid, obeying a
+linear barotropic equation of state, the initial singular state on the brane is
+isotropic. This result is obtained by assuming that in the limit of small times
+the asymptotic behavior of the scale factors is of Kasner-type. For brane
+worlds filled with dust, the initial values of the anisotropy coincide in both
+brane world and standard four-dimensional general relativistic cosmologies.",0401069v1
+2000-09-07,Jet Quenching and Azimuthal Anisotropy of Large $p_T$ Spectra in Non-central High-energy Heavy-ion Collisions,"Parton energy loss inside a dense medium leads to the suppression of large
+$p_T$ hadrons and can also cause azimuthal anisotropy of hadron spectra at
+large transverse momentum in non-central high-energy heavy-ion collisions. Such
+azimuthal anisotropy is studied qualitatively in a parton model for heavy-ion
+collisions at the RHIC energies. The coefficient $v_2(p_T)$ of the elliptic
+anisotropy at large $p_T$ is found to be very sensitive to parton energy loss.
+It decreases slowly with $p_T$ contrary to its low $p_T$ behavior where $v_2$
+increases very rapidly with $p_T$. The turning point signals the onset of
+contributions of hard processes and the magnitude of parton energy loss. The
+centrality dependence of $v_2(p_T)$ is shown to be sensitive to both size and
+density dependence of the parton energy loss and the later can also be studied
+via variation of the colliding energy. The anisotropy coefficient
+$v_2/\epsilon$ normalized by the spatial ellipticity $\epsilon$ is found to
+decrease significantly toward semi-peripheral collisions, differing from the
+hydrodynamic results for low $p_T$ hadrons. Constrained by the existing WA98
+experimental data at the SPS energy on parton energy loss, both hadron spectra
+suppression and azimuthal anisotropy at high $p_T$ are predicted to vanish for
+$b>$7-8 fm in $Au+Au$ collisions at $\sqrt{s}=$130-200 GeV when the hadron
+rapidity density per unit area of the initial overlapped region is less than
+what is achieved in the central $Pb+Pb$ collisions at the SPS energy.",0009019v2
+2008-06-11,Study of reconnection-associated multi-scale fluctuations with Cluster and Double Star,"The objective of the paper is to asses the specific spectral scaling
+properties of magnetic reconnection associated fluctuations/turbulence at the
+Earthward and tailward outflow regions observed simultaneously by the Cluster
+and Double Star (TC-2) spacecraft on September 26, 2005. Systematic comparisons
+of spectral characteristics, including variance anisotropy and scale-dependent
+spectral anisotropy features in wave vector space were possible due to the
+well-documented reconnection events, occurring between the positions of Cluster
+(X = -14--16 $R_e$) and TC-2 (X = -6.6 $R_e$). Another factor of key importance
+is that the magnetometers on the spacecraft are similar. The comparisons
+provide further evidence for asymmetry of physical processes in
+Earthward/tailward reconnection outflow regions. Variance anisotropy and
+spectral anisotropy angles estimated from the multi-scale magnetic fluctuations
+in the tailward outflow region show features which are characteristic for
+magnetohydrodynamic cascading turbulence in the presence of a local mean
+magnetic field. The multi-scale magnetic fluctuations in the Earthward outflow
+region are exhibiting more power, lack of variance and scale dependent
+anisotropies, but also having larger anisotropy angles. In this region the
+magnetic field is more dipolar, the main processes driving turbulence are flow
+breaking/mixing, perhaps combined with turbulence ageing and non-cascade
+related multi-scale energy sources.",0806.1829v1
+2008-11-03,Two-component galaxy models: the effect of density profile at large radii on the phase-space consistency,"It is well known that the density and anisotropy profile in the inner regions
+of a stellar system with positive phase-space distribution function are not
+fully independent. Here we study the interplay between density profile and
+orbital anisotropy at large radii in physically admissible (consistent) stellar
+systems. The analysis is carried out by using two-component (n-gamma,gamma_1)
+spherical self-consistent galaxy models, in which one density distribution
+follows a generalized gamma profile with external logarithmic slope n, and the
+other a standard gamma_1 profile (with external slope 4). The necessary and
+sufficient conditions for phase-space consistency are determined analytically,
+also in presence of a dominant massive central black hole, and the analytical
+phase-space distribution function of (n-gamma,1) models, and of n-gamma models
+with a central black hole, is derived for gamma=0,1,2. It is found that the
+density slope in the external regions of a stellar system can play an important
+role in determining the amount of admissible anisotropy: in particular, for
+fixed density slopes in the central regions, systems with a steeper external
+density profile can support more radial anisotropy than externally flatter
+models. This is quantified by an inequality formally identical to the ``cusp
+slope-central anisotropy'' theorem (An & Evans 2006), relating at all radii
+(and not just at the center) the density logarithmic slope and the anisotropy
+indicator in all Osipkov-Merritt systems [Abridged].",0811.0322v1
+2009-01-30,Ferromagnetism in Co7(TeO3)4Br6: A byproduct of complex antiferromagnetic order and single-ion anisotropy,"Pronounced anisotropy of magnetic properties and complex magnetic order of a
+new oxi-halide compound Co7(TeO3)4Br6 has been investigated by powder and
+single crystal neutron diffraction, magnetization and ac susceptibility
+techniques. Anisotropy of susceptibility extends far into the paramagnetic
+temperature range. A principal source of anisotropy are anisotropic properties
+of the involved octahedrally coordinated single Co(2+) ions, as confirmed by
+angular-overlap-model calculations presented in this work. Incommensurate
+antiferromagnetic order sets in at TN=34 K. Propagation vector is strongly
+temperature dependent reaching k1=(0.9458(6), 0, 0.6026(5)) at 30 K. A
+transition to a ferrimagnetic structure with k2=0 takes place at TC=27 K.
+Magnetically ordered phase is characterized by very unusual anisotropy as well:
+while M-H scans along b-axis reveals spectacularly rectangular but otherwise
+standard ferromagnetic hysteresis loops, M-H studies along other two principal
+axes are perfectly reversible, revealing very sharp spin flop (or spin flip)
+transitions, like in a standard antiferromagnet (or metamagnet). Altogether,
+the observed magnetic phenomenology is interpreted as an evidence of competing
+magnetic interactions permeating the system, first of all of the single ion
+anisotropy energy and the exchange interactions. Different coordinations of the
+Co(2+)-ions involved in the low-symmetry C2/c structure of Co7(TeO3)4Br6 render
+the exchange-interaction network very complex by itself. Temperature dependent
+changes in the magnetic structure, together with an abrupt emergence of a
+ferromagnetic component, are ascribed to continual spin reorientations
+described by a multi-component, but yet unknown, spin Hamiltonian.",0901.4878v1
+2009-05-04,Magnetization Plateaux in the Antiferromagnetic Ising Chain with Single-Ion Anisotropy,"Two one-dimensional spin-1 antiferromagnetic Ising models with a single-ion
+anisotropy under external magnetic field at low temperatures are exactly
+investigated by the transfer-matrix technique. The magnetization per spin ($m$)
+is obtained for the two types of models (denoted by model 1 and 2) as an
+explicit function of the magnetic field ($H$%) and of the anisotropy parameter
+($D$). Model 1 is an extension of the recently one treated by Ohanyan and
+Ananikian [\emph{Phys. Lett. A} \textbf{% 307} (2003) 76]: we have generalized
+their model to the spin-1 case and a single-ion anisotropy term have been
+included. In the limit of positive (or null) anisotropy ($D\geq 0$) and strong
+antiferromagnetic coupling ($\alpha =J_{A}/J_{F}\geq 3$) the $m \times H$
+curves are qualitatively the same as for the spin $S=1/2$ case, with the
+presence of only one plateau at $m/m_{sat}=1/3$. On the other hand, for
+negative anisotropy ($D<0$) we observe more plateaux ($m=1/6$ and 2/3), which
+depend on the values of $D$ and $% \alpha $. The second model (model 2) is the
+same as the one recently studied by Chen et al. [\emph{J. Mag. Mag. Mat.
+}\textbf{262} (2003) 258)] using Monte Carlo simulation; here, the model is
+treated within an exact transfer-matrix framework.",0905.0505v1
+2009-07-29,"Domain walls, canted states and stripe width variation in ultrathin magnetic films with perpendicular anisotropy","Stripe width variation in ultrathin magnetic films is a well known phenomenon
+still not well understood. We analyze this problem considering a 2D Heisenberg
+model with ferromagnetic exchange interactions, dipolar interactions and
+perpendicular anisotropy, relevant e.g. in Fe/Cu(001) films. By extending a
+classic result of Yafet & Gyorgy (YG) and using Monte Carlo simulations we
+calculate the complete zero temperature phase diagram of the model. Through
+this calculation we analyze the correlation between domain walls structure and
+stripe width variation, as the perpendicular anisotropy changes. In particular,
+we found evidences that the recently detected canted state becomes the ground
+state of the system close to the Spin Reorientation Transition (SRT) for any
+value of the exchange to dipolar couplings ratio. Far away of the SRT the
+canted ground state is replaced by a saturated stripes state, in which
+in--plane magnetization components are only present inside the walls. We find
+that the domain wall structure strongly depends on the perpendicular
+anisotropy: close to SRT it is well described by YG approximation, but a strong
+departure is observed in the large anisotropy limit. Moreover, we show that
+stripe width variation is directly related to domain wall width variation with
+the anisotropy.",0907.5153v1
+2010-01-22,Non-Gaussianity and the Cosmic Microwave Background Anisotropies,"We review in a pedagogical way the present status of the impact of
+non-Gaussianity (NG) on the Cosmic Microwave Background (CMB) anisotropies. We
+first show how to set the initial conditions at second-order for the (gauge
+invariant) CMB anisotropies when some primordial NG is present. However, there
+are many sources of NG in CMB anisotropies, beyond the primordial one, which
+can contaminate the primordial signal. We mainly focus on the NG generated from
+the post-inflationary evolution of the CMB anisotropies at second-order in
+perturbation theory at large and small angular scales, such as the ones
+generated at the recombination epoch. We show how to derive the equations to
+study the second-order CMB anisotropies and provide analytical computations to
+evaluate their contamination to primordial NG (complemented with numerical
+examples). We also offer a brief summary of other secondary effects. This
+review requires basic knowledge of the theory of cosmological perturbations at
+the linear level.",1001.3957v1
+2010-04-22,Numerical study on the emergence of anisotropy in artificial flocks: A BOIDS modeling and simulations of empirical findings,"In real flocks, it was revealed that the angular density of nearest neighbors
+shows a strong {\it anisotropic structure} of individuals by very recent
+extensive field studies by Ballerini et al [{\it Proceedings of the National
+Academy of Sciences USA} {\bf 105}, pp.1232-1237 (2008)]. In this paper, we
+show that this empirical evidence in real flocks, namely, the structure of
+anisotropy also emerges in an artificial flock simulation based on the {\it
+BOIDS} by Reynolds [{\it Computer Graphics} {\bf 21}, pp.25-34 (1987)]. We
+numerically find that appropriate combinations of the weights for just only
+three essential factors of the BOIDS, namely, `Cohesion', `Alignment' and
+`Separation' lead to a strong anisotropy in the flock. This result seems to be
+highly counter-intuitive and also provides a justification of the hypothesis
+that the anisotropy emerges as a result of self-organization of interacting
+intelligent agents (birds for instance). To quantify the anisotropy, we
+evaluate a useful statistics (a kind of {\it order parameters} in statistical
+physics), that is to say, the so-called $\gamma$-value defined as an inner
+product between the vector in the direction of the lowest angular density of
+flocks and the vector in the direction of the moving of the flock. Our results
+concerning the emergence of the anisotropy through the $\gamma$-value might
+enable us to judge whether an arbitrary flock simulation seems to be {\it
+realistic} or not.",1004.3837v1
+2010-05-04,CMB in a box: causal structure and the Fourier-Bessel expansion,"This paper makes two points. First, we show that the line-of-sight solution
+to cosmic microwave anisotropies in Fourier space, even though formally defined
+for arbitrarily large wavelengths, leads to position-space solutions which only
+depend on the sources of anisotropies inside the past light-cone of the
+observer. This happens order by order in a series expansion in powers of the
+visibility $\gamma=e^{-\mu}$, where $\mu$ is the optical depth to Thompson
+scattering. We show that the CMB anisotropies are regulated by spacetime window
+functions which have support only inside the past light-cone of the point of
+observation. Second, we show that the Fourier-Bessel expansion of the physical
+fields (including the temperature and polarization momenta) is an alternative
+to the usual Fourier basis as a framework to compute the anisotropies. In that
+expansion, for each multipole $l$ there is a discrete tower of momenta
+$k_{i,l}$ (not a continuum) which can affect physical observables, with the
+smallest momenta being $k_{1,l} ~ l$. The Fourier-Bessel modes take into
+account precisely the information from the sources of anisotropies that
+propagates from the initial value surface to the point of observation - no
+more, no less. We also show that the physical observables (the temperature and
+polarization maps), and hence the angular power spectra, are unaffected by that
+choice of basis. This implies that the Fourier-Bessel expansion is the optimal
+scheme with which one can compute CMB anisotropies. (Abridged)",1005.0563v1
+2010-08-07,T=0 phase diagram and nature of domains in ultrathin ferromagnetic films with perpendicular anisotropy,"We present the complete zero temperature phase diagram of a model for
+ultrathin films with perpendicular anisotropy. The whole parameter space of
+relevant coupling constants is studied in first order anisotropy approximation.
+Because the ground state is known to be formed by perpendicular stripes
+separated by Bloch walls, a standard variational approach is used, complemented
+with specially designed Monte Carlo simulations. We can distinguish four
+regimes according to the different nature of striped domains: a high anisotropy
+Ising regime with sharp domain walls, a saturated stripe regime with thicker
+walls inside which an in-plane component of the magnetization develops, a
+narrow canted-like regime, characterized by a sinusoidal variation of both the
+in-plane and the out of plane magnetization components, which upon further
+decrease of the anisotropy leads to an in-plane ferromagnetic state via a spin
+reorientation transition (SRT). The nature of domains and walls are described
+in some detail together with the variation of domain width with anisotropy, for
+any value of exchange and dipolar interactions. Our results, although strictly
+valid at $T=0$, can be valuable for interpreting data on the evolution of
+domain width at finite temperature, a still largely open problem.",1008.1353v1
+2010-11-30,Dark matter electron anisotropy: a universal upper limit,"We study the dipole anisotropy in the arrival directions of high energy CR
+electrons and positrons (CRE) of Dark Matter (DM) origin. We show that this
+quantity is very weakly model dependent and offers a viable criterion to
+discriminate among CRE from DM or from local discrete sources, like e.g.
+pulsars. In particular, we find that the maximum anisotropy which DM can
+provide is to a very good approximation a universal quantity and, as a
+consequence, if a larger anisotropy is detected, this would constitute a strong
+evidence for the presence of astrophysical local discrete CRE sources, whose
+anisotropy, instead, can be naturally larger than the DM upper limit. We
+further find that the main source of anisotropy from DM is given by the
+fluctuation in the number density of DM sub-structures in the vicinity of the
+observer and we thus devote special attention to the study of the variance in
+the sub-structures realization implementing a dedicated Montecarlo simulation.
+Such scenarios will be probed in the next years by Fermi-LAT, providing new
+hints, or constraints, about the nature of DM.",1012.0041v3
+2011-01-27,Anisotropy as a Probe of the Galactic Cosmic Ray Propagation and the Galactic Halo Magnetic Field,"The anisotropy of cosmic rays (CRs) in the solar vicinity is generally at-
+tributed to the CR streaming due to the discrete distribution of CR sources or
+local magnetic field modulation. Recently, the two dimensional large scale CR
+anisotropy has been measured by many experiments in TeV-PeV energy range in
+both hemispheres. The tail-in excess along the tangential direction of the
+local spiral arm and the loss cone deficit pointing to the north Galactic pole
+direction agree with what have been obtained in tens to hundreds of GeV. The
+persistence of the two large scale anisotropy structures in such a wide range
+of energy suggests that the anisotropy might be due to a global streaming of
+the Galactic CRs (GCRs). This work tries to extend the observed CR anisotropy
+picture from solar system to the whole galaxy. In such a case, we can find a
+new interesting signature, a loop of GCR streaming, of the GCR propagation. We
+further calculate the overall GCR streaming induced magnetic field, and find a
+qualitative consistence with the observed structure of the halo magnetic field.",1101.5273v3
+2011-06-14,The East-West method: an exposure-independent method to search for large scale anisotropies of cosmic rays,"The measurement of large scale anisotropies in cosmic ray arrival directions
+at energies above 10^13 eV is performed through the detection of Extensive Air
+Showers produced by cosmic ray interactions in the atmosphere. The observed
+anisotropies are small, so accurate measurements require small statistical
+uncertainties, i.e. large datasets. These can be obtained by employing ground
+detector arrays with large extensions (from 10^4 to 10^9 m^2) and long
+operation time (up to 20 years). The control of such arrays is challenging and
+spurious variations in the counting rate due to instrumental effects (e.g. data
+taking interruptions or changes in the acceptance) and atmospheric effects
+(e.g. air temperature and pressure effects on EAS development) are usually
+present. These modulations must be corrected very precisely before performing
+standard anisotropy analyses, i.e. harmonic analysis of the counting rate
+versus local sidereal time. In this paper we discuss an alternative method to
+measure large scale anisotropies, the ""East-West method"", originally proposed
+by Nagashima in 1989. It is a differential method, as it is based on the
+analysis of the difference of the counting rates in the East and West
+directions. Besides explaining the principle, we present here its mathematical
+derivation, showing that the method is largely independent of experimental
+effects, that is, it does not require corrections for acceptance and/or for
+atmospheric effects. We explain the use of the method to derive the amplitude
+and phase of the anisotropy and we demonstrate its power under different
+conditions of detector operation.",1106.2651v1
+2011-07-21,An Estimator for statistical anisotropy from the CMB bispectrum,"Various data analyses of the Cosmic Microwave Background (CMB) provide
+observational hints of statistical isotropy breaking. Some of these features
+can be studied within the framework of primordial vector fields in inflationary
+theories which generally display some level of statistical anisotropy both in
+the power spectrum and in higher-order correlation functions. Motivated by
+these observations and the recent theoretical developments in the study of
+primordial vector fields, we develop the formalism necessary to extract
+statistical anisotropy information from the three-point function of the CMB
+temperature anisotropy. We employ a simplified vector field model and
+parametrize the bispectrum of curvature fluctuations in such a way that all the
+information about statistical anisotropy is encoded in some parameters
+lambda_{LM} (which measure the anisotropic to the isotropic bispectrum
+amplitudes). For such a template bispectrum, we compute an optimal estimator
+for lambda_{LM} and the expected signal-to-noise ratio. We estimate that, for
+f_{NL} ~ 30, an experiment like Planck can be sensitive to a ratio of the
+anisotropic to the isotropic amplitudes of the bispectrum as small as 10%. Our
+results are complementary to the information coming from a power spectrum
+analysis and particularly relevant for those models where statistical
+anisotropy turns out to be suppressed in the power spectrum but not negligible
+in the bispectrum.",1107.4304v2
+2012-06-20,Models of the Contribution of Blazars to the Anisotropy of the Extragalactic Diffuse Gamma-ray Background,"We study the relation between the measured anisotropies in the extragalactic
+diffuse gamma-ray background (DGRB) and the DGRB spectral intensity, and their
+potential origin from the unresolved blazar population. Using a
+physical-evolution model for blazars with a luminosity dependent evolution
+(LDDE) and an observationally-determined luminosity-dependent blazar spectral
+energy distribution (SED), we find that blazars can account for the observed
+anisotropy of the DGRB consistent with their observed source-count
+distribution, but are in turn constrained in contributing significantly to the
+observed DGRB intensity. For the best-fit LDDE model accounting for the DGRB
+anisotropy and source-count distribution, blazars only contribute
+5.7^{+2.1}_{-1.0}% (68% CL) of the DGRB intensity above 1 GeV. Requiring a
+higher fraction of the DGRB intensity contribution by blazars overproduces the
+DGRB anisotropy, and therefore blazars in the LDDE+SED-sequence model cannot
+simultaneously account for the DGRB intensity as well as anisotropy. We discuss
+the limitations of LDDE models. However, these models do not require the many
+unjustified and observationally-inconsistent simplifying
+assumptions---including a single power law for all blazar spectra and a simple
+broken power-law model for their source-count distribution---that are present
+in much previous work.",1206.4734v2
+2012-10-08,Magnetic anisotropy in strained manganite films and bicrystal junctions,"Transport and magnetic properties of LSMO manganite thin films and bicrystal
+junctions were investigated. Manganite films were epitaxially grown on STO,
+LAO, NGO and LSAT substrates and their magnetic anisotropy were determined by
+two techniques of magnetic resonance spectroscopy. Compare with cubic
+substrates a small (about 0.3 persentage), the anisotropy of the orthorhombic
+NGO substrate leads to a uniaxial anisotropy of the magnetic properties of the
+films in the plane of the substrate. Samples with different tilt of
+crystallographic basal planes of manganite as well as bicrystal junctions with
+rotation of the crystallographic axes (RB - junction) and with tilting of basal
+planes (TB - junction) were investigated. It was found that on vicinal NGO
+substrates the value of magnetic anisotropy could be varied by changing the
+substrate inclination angle from 0 to 25 degrees. Measurement of magnetic
+anisotropy of manganite bicrystal junction demonstrated the presence of two
+ferromagnetically ordered spin subsystems for both types of bicrystal
+boundaries RB and TB. The magnitude of the magnetoresistance for TB - junctions
+increased with decreasing temperature and with the misorientation angle even
+misorientation of easy axes in the parts of junction does not change. Analysis
+of the voltage dependencies of bicrystal junction conductivity show that the
+low value of the magnetoresistance for the LSMO bicrystal junctions can be
+caused by two scattering mechanisms with the spin- flip of spin - polarized
+carriers due to the strong electron - electron interactions in a disordered
+layer at the bicrystal boundary at low temperatures and the spin-flip by anti
+ferromagnetic magnons at high temperatures.",1210.2261v1
+2012-10-08,The behaviour of shape and velocity anisotropy in dark matter haloes,"Dark matter haloes from cosmological N-body simulations typically have
+triaxial shapes and anisotropic velocity distributions. Recently it has been
+shown that the velocity anisotropy, beta, of cosmological haloes and major
+merger remnants depends on direction in such a way that beta is largest along
+the major axis and smallest along the minor axis. In this work we use a wide
+range of non-cosmological N-body simulations to examine halo shapes and
+direction-dependence of velocity anisotropy profiles. For each of our simulated
+haloes we define 48 cones pointing in different directions, and from the
+particles inside each cone we compute velocity anisotropy profiles. We find
+that elongated haloes can have very distinct velocity anisotropies. We group
+the behaviour of haloes into three different categories, that range from
+spherically symmetric profiles to a much more complex behaviour, where
+significant differences are found for beta along the major and minor axes. We
+encourage future studies of velocity anisotropies in haloes from cosmological
+simulations to calculate beta-profiles in cones, since it reveals information,
+which is hidden from a spherically averaged profile. Finally, we show that
+spherically averaged profiles often obey a linear relation between beta and the
+logarithmic density slope in the inner parts of haloes, but this relation is
+not necessarily obeyed, when properties are calculated in cones.",1210.2392v1
+2013-01-21,Increase of magnetic hyperthermia efficiency due to dipolar interactions in low anisotropy magnetic nanoparticles : theoretical and experimental results,"When magnetic nanoparticles (MNPs) are single-domain and magnetically
+independent, their magnetic properties and the conditions to optimize their
+efficiency in magnetic hyperthermia applications are now well-understood.
+However, the influence of magnetic interactions on magnetic hyperthermia
+properties is still unclear. Here, we report hyperthermia and high-frequency
+hysteresis loop measurements on a model system consisting of MNPs with the same
+size but a varying anisotropy, which is an interesting way to tune the relative
+strength of magnetic interactions. A clear correlation between the MNP
+anisotropy and the squareness of their hysteresis loop in colloidal solution is
+observed : the larger the anisotropy, the smaller the squareness. Since low
+anisotropy MNPs display a squareness higher than the one of magnetically
+independent nanoparticles, magnetic interactions enhance their heating power in
+this case. Hysteresis loop calculations of independent and coupled MNPs are
+compared to experimental results. It is shown that the observed features are a
+natural consequence of the formation of chains and columns of MNPs during
+hyperthermia experiments: in these structures, when the MNP magnetocristalline
+anisotropy is small enough to be dominated by magnetic interactions, the
+hysteresis loop shape tends to be rectangular, which enhance their efficiency.
+On the contrary, when MNPs do not form chains and columns, magnetic
+interactions reduces the hysteresis loop squareness and the efficiency of MNPs
+compared to independent ones. The present work should improve the understanding
+and interpretation of magnetic hyperthermia experiments.",1301.5590v1
+2013-06-20,"Magnetic orders, excitations, and phase transitions in Fe_1+yTe","We study the magnetic properties of Fe_1+y Te, a parent compound of the
+iron-based high-temperature superconductors. Motivated by recent neutron
+scattering experiments, we show that a spin-1 exchange model, supplemented by a
+single-ion spin anisotropy, accounts well for the experimentally observed low
+temperature magnetic phase diagram, that exhibits a commensurate bicollinear
+order at low Fe dopings (y < 0.12) and an incommensurate spin-spiral order at
+high Fe dopings (y > 0.12). We suggest that the commensurate-incommensurate
+transition at y = 0.12 is due to the competition between the exchange
+interaction and the local spin anisotropy. At low Fe dopings, the single-ion
+spin anisotropy is strong and pins the spins along the easy axis, which,
+together with the spatially anisotropic exchanges, induces a unusual
+bicollinear commensurate magnetic order. The low-energy spin-wave excitation is
+gapped due to the explict breaking of spin-rotational symmetry by the local
+spin anisotropy. At high Fe dopings, the single-ion anisotropy is weak, and the
+exchange favors an incommensurate coplanar state. The incommensurate magnetic
+wavevector averages out the spin anisotropy so that a gapless low-energy
+spin-wave excitation is obtained. We also analyze the low-energy hydrodynamic
+model and use it to describe the magneto-structural transition and the static
+and dynamical spin structure factors across the magnetic ordering transitions.",1306.4730v2
+2013-06-23,Characterising gravitational wave stochastic background anisotropy with Pulsar Timing Arrays,"Detecting a stochastic gravitational wave background, particularly radiation
+from individually unresolvable super-massive black hole binary systems, is one
+of the primary targets for Pulsar Timing Arrays. Increasingly more stringent
+upper limits are being set on these signals under the assumption that the
+background radiation is isotropic. However, some level of anisotropy may be
+present and the characterisation of the power at different angular scales
+carries important information. We show that the standard analysis for isotropic
+backgrounds can be generalised in a conceptually straightforward way to the
+case of generic anisotropic background radiation by decomposing the angular
+distribution of the gravitational wave power on the sky into multipole moments.
+We introduce the concept of generalised overlap reduction functions which
+characterise the effect of the anisotropy multipoles on the correlation of the
+timing residuals from the pulsars timed by a Pulsar Timing Array. In a search
+for a signal characterised by a generic anisotropy, the generalised overlap
+reduction functions play the role of the so-called Hellings and Downs curve
+used for isotropic radiation. We compute the generalised overlap reduction
+functions for a generic level of anisotropy and Pulsar Timing Array
+configuration. We also provide an order of magnitude estimate of the level of
+anisotropy that can be expected in the background generated by super-massive
+black hole binary systems.",1306.5394v2
+2013-08-19,Dipole Anisotropy in Integrated Linearly Polarized Flux Density in NVSS Data,"We study the dipole anisotropy in integrated linearly polarization flux
+density in NRAO VLA Sky Survey (NVSS). We extract the anisotropy parameters in
+the number counts, number counts weighted by polarization observables, i.e.
+degree of polarization (p) and polarization flux (P). We also determine the
+anisotropy in the degree of polarization per source and polarization flux per
+source. We consider data with several different cuts on the flux density,
+S>10,20,30,40,50 mJy. For studies with degree of polarization we impose the
+additional cut 0.01<p<1. Similarly for polarization flux we impose, 0.5<P<100
+mJy. We find a very significant signal of dipole, both in number counts and P
+(or p) weighted number counts. For the case of P weighted number counts the
+significance ranges from 8 \sigma to 5 \sigma for S>20 mJy to S>50 mJy. The
+corresponding direction parameters are found to be stable with the cut on flux
+density. The significance is even higher for the case of p weighted number
+counts. The observed anisotropy is found to be much larger in comparison to the
+CMBR expectations. We find that polarization observables show a much higher
+level of anisotropy in comparison to pure number counts or flux weighted number
+counts.",1308.3970v2
+2013-09-27,The Effect of 45° Grain Boundaries and associated Fe particles on Jc and resistivity in Ba(Fe0.9Co0.1)2As2 Thin Films,"The anisotropy of the critical current density Jc depends in general on both
+the properties of the flux lines (such as line tension, coherence length and
+penetration depth) and the properties of the defects (such as density, shape,
+orientation etc.). Whereas the Jc anisotropy in microstructurally clean films
+can be scaled to an effective magnetic field containing the Ginzburg-Landau
+anisotropy term, it is in general not possible (or only in a limited field
+range) for samples containing extended defects. Here, the Jc anisotropy of a
+Co-doped BaFe2As2 sample with 45{\deg} [001] tilt grain boundaries (GBs), i.e.
+grain boundaries created by 45{\deg} in-plane rotated grains, as well as
+extended Fe particles is investigated. This microstructure leads to c-axis
+correlated pinning, both due to the GBs and the Fe particles and manifests in a
+c-axis peak in the Jc anisotropy at low magnetic fields and a deviation from
+the anisotropic Ginzburg-Landau scaling at higher fields. Strong pinning at
+ellipsoidal extended defects, i.e. the Fe particles, is discussed, and the full
+Jc anisotropy is fitted successfully with the vortex path model. The results
+are compared to a sample without GBs and Fe particles. 45{\deg} GBs seem to be
+good pinning centers rather than detrimental to current flow.",1309.7182v1
+2014-04-07,Cross-correlation of cosmic far-infrared background anisotropies with large scale structures,"We measure the cross-power spectra between luminous red galaxies (LRGs) from
+the Sloan Digital Sky Survey (SDSS)-III Data Release Eight (DR8) and cosmic
+infrared background (CIB) anisotropies from Planck and data from the Improved
+Reprocessing (IRIS) of the Infrared Astronomical Satellite (IRAS) at 353, 545,
+857, and 3000 GHz, corresponding to 850, 550, 350 and 100 micron, respectively,
+in the multipole range 100<l<1000. Using approximately 6.5 10^5 photometrically
+determined LRGs in 7760 deg^2 of the northern hemisphere in the redshift range
+0.45 < z < 0.65, we model the far-infrared background (FIRB) anisotropies with
+an extended version of the halo model. With these methods, we confirm the basic
+picture obtained from recent analyses of FIRB anisotropies with Herschel and
+Planck, that the most efficient halo mass at hosting star forming galaxies is
+log(M_ eff/M_\odot)=12.84+/-0.15. We estimate the percentage of FIRB
+anisotropies correlated with LRGs as approximately 11.8 %, 3.9 %, 1.8 %, and
+1.0 % of the total at 3000, 857, 545, and 353 GHz, respectively. At redshift
+z~0.55, the bias of FIRB galaxies with respect to the dark matter density field
+has the value b_{FIRB}~1.45, and the mean dust temperature of FIRB galaxies is
+T_d=26 K. Finally, we discuss the impact of present and upcoming
+cross-correlations with far-infrared background anisotropies on the
+determination of the global star formation history and the link between
+galaxies and dark matter.",1404.1933v2
+2014-04-15,Anisotropic upper critical field of BiS2-based superconductor LaO0.5F0.5BiS2,"Superconducting properties under high magnetic fields for the novel
+BiS2-based layered superconductor LaO0.5F0.5BiS2 (polycrystalline sample
+prepared using the high-pressure synthesis method) have been investigated. The
+anisotropy of the upper critical field was discussed by analyzing the
+temperature dependence of the temperature derivative of resistivity. The
+temperature dependence of upper critical field showed an anomalous behavior
+with a characteristic magnetic field of 8 T. We revealed that the anomalous
+behavior was caused by the existence of three kinds of upper critical field,
+HC2max, HC2mid and HC2min in LaO0.5F0.5BiS2. The lowest upper critical field
+HC2min is regarded as the Hc2 where the superconducting states of the grains
+with an orientation of H // c are suppressed. The HC2max and HC2mid are
+regarded as the Hc2 where the superconducting states of the grains with an
+orientation of H // ab are suppressed. The difference between the HC2max and
+HC2mid could be explained by the anisotropy of superconducting states within
+the Bi-S plane. The estimated anisotropy parameter of the upper critical fields
+was about 7.4 for the high-pressure-synthesized LaO0.5F0.5BiS2 polycrystalline
+sample. Since the value was clearly lower than the anisotropy parameter of over
+30 observed in the previous report on the LaO0.5F0.5BiS2 single crystals grown
+under ambient pressure, we concluded that a larger anisotropy of
+superconductivity was not essential for the enhancement of Tc, and lower
+anisotropy might be important for a higher Tc in LaO1-xFxBiS2.",1404.3798v1
+2014-05-14,Shrinkage anisotropy characteristics from soil structure and initial sample/layer size,"The objective of this work is a physical prediction of such soil shrinkage
+anisotropy characteristics as variation with drying of (i) different
+sample/layer sizes and (ii) the shrinkage geometry factor. With that, a new
+presentation of the shrinkage anisotropy concept is suggested through the
+sample/layer size ratios. The work objective is reached in two steps. First,
+the relations are derived between the indicated soil shrinkage anisotropy
+characteristics and three different shrinkage curves of a soil relating to:
+small samples (without cracking at shrinkage), sufficiently large samples (with
+internal cracking), and layers of similar thickness. Then, the results of a
+recent work with respect to the physical prediction of the three shrinkage
+curves are used. These results connect the shrinkage curves with the initial
+sample size/layer thickness as well as characteristics of soil texture and
+structure (both inter- and intra-aggregate) as physical parameters. The
+parameters determining the reference shrinkage curve (relating to the small
+samples) and initial sample size/layer thickness are needed for the prediction
+of the above soil shrinkage anisotropy characteristics. Using the available
+data on two soils and samples of two essentially different sizes, illustrative
+estimates of the relative sample sizes, new characteristic of the shrinkage
+anisotropy, and shrinkage geometry factor are given as the physically predicted
+values.",1405.3409v1
+2015-05-11,Imprint of a 2 Myr old source on the cosmic ray anisotropy,"We study numerically the anisotropy of the cosmic ray (CR) flux emitted by a
+single source calculating the trajectories of individual CRs. We show that the
+contribution of a single source to the observed anisotropy is instead
+determined solely by the fraction the source contributes to the total CR
+intensity, its age and its distance,and does not depend on the CR energy at
+late times. Therefore the observation of a constant dipole anisotropy indicates
+that a single source dominates the CR flux in the corresponding energy range. A
+natural explanation for the plateau between 2--20 TeV observed in the CR
+anisotropy is thus the presence of a single, nearby source. For the source age
+of 2 Myr, as suggested by the explanation of the antiproton and positron data
+from PAMELA and AMS-02 through a local source [arXiv:astro-ph/1504.06472], we
+determine the source distance as $\sim 200$ pc. Combined with the contribution
+of the global CR sea calculated in the escape model, we can explain
+qualitatively the data for the dipole anisotropy. Our results suggest that the
+assumption of a smooth CR source distribution should be abandoned between 200
+GeV and 1 PeV.",1505.02720v2
+2015-06-09,Macroscopic model with anisotropy based on micro-macro informations,"Physical experiments can characterize the elastic response of granular
+materials in terms of macroscopic state-variables, namely volume (packing)
+fraction and stress, while the microstructure is not accessible and thus
+neglected. Here, by means of numerical simulations, we analyze dense,
+frictionless, granular assemblies with the final goal to relate the elastic
+moduli to the fabric state, i.e., to micro-structural averaged contact network
+features as contact number density and anisotropy.
+  The particle samples are first isotropically compressed and later
+quasi-statically sheared under constant volume (undrained conditions). From
+various static, relaxed configurations at different shear strains, now
+infinitesimal strain steps are applied to ""measure"" the effective elastic
+response; we quantify the strain needed so that plasticity in the sample
+develops as soon as contact and structure rearrangements happen. Because of the
+anisotropy induced by shear, volumetric and deviatoric stresses and strains are
+cross-coupled via a single anisotropy modulus, which is proportional to the
+product of deviatoric fabric and bulk modulus (i.e. the isotropic fabric).
+Interestingly, the shear modulus of the material depends also on the actual
+stress state, along with the contact configuration anisotropy.
+  Finally, a constitutive model based on incremental evolution equations for
+stress and fabric is introduced. By using the previously measured dependence of
+the stiffness tensor (elastic moduli) on the microstructure, the theory is able
+to predict with good agreement the evolution of pressure, shear stress and
+deviatoric fabric (anisotropy) for an independent undrained cyclic shear test,
+including the response to reversal of strain.",1506.02992v2
+2015-07-27,Ultrafast laser-induced changes of the magnetic anisotropy in a low-symmetry iron garnet film,"We explore a thermal mechanism of changing the anisotropy by femtosecond
+laser pulses in dielectric ferrimagnetic garnets by taking a low symmetry
+(YBiPrLu)3(FeGa)5O12 film grown on the (210)-oriented Gd3Ga5O12 substrate as a
+model media. We demonstrate by means of spectral magneto-optical pump-probe
+technique and phenomenological analysis, that the magnetization precession in
+such a film is triggered by laser-induced changes of the growth-induced
+magnetic anisotropy along with the well-known ultrafast inverse Faraday effect.
+The change of magnetic anisotropy is mediated by the lattice heating induced by
+laser pulses of arbitrary polarization on a picosecond time scale. We show that
+the orientation of the external magnetic field with respect to the
+magnetization easy plane noticeably affects the precession excited via the
+anisotropy change. Importantly, the relative contributions from the ultrafast
+inverse Faraday effect and the change of different growth-induced anisotropy
+parameters can be controlled by varying the applied magnetic field strength and
+direction. As a result, the amplitude and the initial phase of the excited
+magnetization precession can be gradually tuned.",1507.07437v2
+2015-09-02,Cosmic Ray Small Scale Anisotropies and Local Turbulent Magnetic Fields,"Cosmic ray anisotropy has been observed in a wide energy range and at
+different angular scales by a variety of experiments over the past decade.
+However, no comprehensive or satisfactory explanation has been put forth to
+date. The arrival distribution of cosmic rays at Earth is the convolution of
+the distribution of their sources and of the effects of geometry and properties
+of the magnetic field through which particles propagate. It is generally
+believed that the anisotropy topology at the largest angular scale is
+adiabatically shaped by diffusion in the structured interstellar magnetic
+field. On the contrary, the medium- and small-scale angular structure could be
+an effect of non-diffusive propagation of cosmic rays in perturbed magnetic
+fields. In particular, a possible explanation of the observed small-scale
+anisotropy observed at TeV energy scale, may come from the effect of particle
+scattering in turbulent magnetized plasmas. We perform numerical integration of
+test particle trajectories in low-$\beta$ compressible magnetohydrodynamic
+turbulence to study how the cosmic rays arrival direction distribution is
+perturbed when they stream along the local turbulent magnetic field. We utilize
+Liouville's theorem for obtaining the anisotropy at Earth and provide the
+theoretical framework for the application of the theorem in the specific case
+of cosmic ray arrival distribution. In this work, we discuss the effects on the
+anisotropy arising from propagation in this inhomogeneous and turbulent
+interstellar magnetic field.",1509.00892v2
+2015-09-15,Overlap distributions for quantum quenches in the anisotropic Heisenberg chain,"The dynamics after a quantum quench is determined by the weights of the
+initial state in the eigenspectrum of the final Hamiltonian, i.e., by the
+distribution of overlaps in the energy spectrum. We present an analysis of such
+overlap distributions for quenches of the anisotropy parameter in the
+one-dimensional anisotropic spin-1/2 Heisenberg model (XXZ chain). We provide
+an overview of the form of the overlap distribution for quenches from various
+initial anisotropies to various final ones, using numerical exact
+diagonalization. We show that if the system is prepared in the
+antiferromagnetic N\'eel state (infinite anisotropy) and released into a
+non-interacting setup (zero anisotropy, XX point) only a small fraction of the
+final eigenstates gives contributions to the post-quench dynamics, and that
+these eigenstates have identical overlap magnitudes. We derive expressions for
+the overlaps, and present the selection rules that determine the final
+eigenstates having nonzero overlap. We use these results to derive concise
+expressions for time-dependent quantities (Loschmidt echo, longitudinal and
+transverse correlators) after the quench. We use perturbative analyses to
+understand the overlap distribution for quenches from infinite to small nonzero
+anisotropies, and for quenches from large to zero anisotropy.",1509.04666v1
+2015-10-29,Strain-induced perpendicular magnetic anisotropy in La$_2$CoMnO$_{6-ε}$ thin films and its dependence with film thickness,"Ferromagnetic insulating La$_2$CoMnO$_{6-\epsilon}$ (LCMO) epitaxial thin
+films grown on top of SrTiO$_3$ (001) substrates presents a strong magnetic
+anisotropy favoring the out of plane orientation of the magnetization with a
+strong anisotropy field ($\sim 70$ kOe for film thickness of about 15 nm) and
+with a coercive field of about 10 kOe. The anisotropy can be tuned by modifying
+the oxygen content of the film which indirectly has two effects on the unit
+cell: i) change of the orientation of the LCMO crystallographic axis over the
+substrate (from c in-plane to c out-of-plane) and ii) shrinkage of the out of
+plane cell parameter, which implies increasing tensile strain of the films. In
+contrast, LCMO films grown on (LaAlO$_3$)$_{0.3}$(Sr$_2$AlTaO$_6$)$_{0.7}$ and
+LaAlO$_3$ substrates (with a larger out-of-plane lattice parameter and
+compressive stress) display in-plane magnetic anisotropy. Thus, we link the
+strong magnetic anisotropy observed in La$_2$CoMnO$_{6-\epsilon}$ to the
+relation between in-plane and out-of-plane parameters and so to the film
+stress.",1510.08685v4
+2015-12-11,Large anisotropy of electron and hole g factors in infrared-emitting InAs/InAlGaAs self-assembled quantum dots,"A detailed study of the $g$-factor anisotropy of electrons and holes in
+InAs/In$_{0.53}$Al$_{0.24}$Ga$_{0.23}$As self-assembled quantum dots emitting
+in the telecom spectral range of $1.5-1.6$ $\mu$m (around 0.8 eV photon energy)
+is performed by time-resolved pump-probe ellipticity technique using a
+superconducting vector magnet. All components of the $g$-factor tensors are
+measured, including their spread in the quantum dot (QD) ensemble.
+Surprisingly, the electron $g$ factor shows a large anisotropy changing from
+$g_{\mathrm{e},x}= -1.63$ to $g_{\mathrm{e},z}= -2.52$ between directions
+perpendicular and parallel to the dot growth axis, respectively, at an energy
+of 0.82 eV. The hole $g$-factor anisotropy at this energy is even stronger:
+$|g_{\text{h},x}|= 0.64$ and $|g_{\text{h},z}|= 2.29$. On the other hand, the
+in-plane anisotropies of electron and hole $g$ factors are small. The
+pronounced out-of-plane anisotropy is also observed for the spread of the $g$
+factors, determined from the spin dephasing time. The hole longitudinal $g$
+factors are described with a theoretical model that allows us to estimate the
+QD parameters. We find that the QD height-to-diameter ratio increases while the
+indium composition decreases with increasing QD emission energy.",1512.03544v3
+2016-02-12,Effects of suprathermal electrons on the proton temperature anisotropy in space plasmas: Electromagnetic ion-cyclotron instability,"In collision-poor plasmas from space, e.g., the solar wind and planetary
+magnetospheres, the kinetic anisotropy of the plasma particles is expected to
+be regulated by the kinetic instabilities. Driven by an excess of ion (proton)
+temperature perpendicular to the magnetic field $(~T_\perp >T_\parallel)$, the
+electromagnetic ion-cyclotron (EMIC) instability is fast enough to constrain
+the proton anisotropy, but the observations do not conform to the instability
+thresholds predicted by the standard theory for bi-Maxwellian models of the
+plasma particles. This paper presents an extended investigation of the EMIC
+instability in the presence of suprathermal electrons which are ubiquitous in
+these environments. The analysis is based on the kinetic (Vlasov-Maxwell)
+theory assuming that both species, protons and electrons, may be anisotropic,
+and the EMIC unstable solutions are derived numerically providing an accurate
+description for conditions typically encountered in space plasmas. The effects
+of suprathermal populations are triggered by the electron anisotropy and the
+temperature contrast between electrons and protons. For certain conditions the
+anisotropy thresholds exceed the limits of the proton anisotropy measured in
+the solar wind considerably restraining the unstable regimes of the EMIC modes.",1602.04051v2
+2016-02-18,Second order anisotropy contribution in perpendicular magnetic tunnel junctions,"Magnetoresistance loops under in-plane applied field were measured on
+perpendicularly magnetized magnetic tunnel junction (pMTJ) pillars with nominal
+diameters ranging from 50 to 150 nm. By fitting the hard-axis magnetoresistance
+loops to an analytical model, the effective anisotropy fields in both free and
+reference layers were derived and their variations in temperature range between
+340K and 5K were determined. It is found that an accurate fitting is possible
+only if a second-order anisotropy term of the form $-K_{2}cos^4{\theta}$, is
+added to the fitting model. This higher order contribution exists both in the
+free and reference layers and its sign is opposite to that of the first order
+anisotropy constant, $K_{1}$. At room temperatures the estimated $-K_{2}/K_{1}$
+ratios are 0.1 and 0.24 for the free and reference layers, respectively. The
+ratio is more than doubled at low temperatures altering the ground state of the
+reference layer from 'easy-axis' to 'easy-cone' regime. Easy-cone state has
+clear signatures in the shape of the hard-axis magnetoresistance loops. The
+same behavior was observed in all measured devices regardless of their
+diameter. The existence of this higher order anisotropy was confirmed
+experimentally on FeCoB/MgO sheet films by ferromagnetic resonance technique.
+It is of interfacial nature and is believed to be linked to spatial
+fluctuations at the nanoscale of the anisotropy parameter at the FeCoB/MgO
+interface, in agreement with Dieny-Vedyayev model.",1602.05815v1
+2016-04-10,Entanglement robustness in Heisenberg spin chains coupled to dissipative environment at finite temperature,"We consider a finite one-dimensional Heisenberg XYZ spin chain under the
+influence of dissipative Lindblad environment obeying the Born-Markovian
+constrain in presence of an external magnetic field. We apply both closed and
+open boundary conditions at zero and finite temperature. We present an exact
+numerical solution for the Lindblad master equation of the system in the
+Liouville space. we find that, in the free spin chain (in absence of any
+environment), the entanglement at all ranges evolve in time in a non-uniform
+oscillatory form that changes significantly depending on the initial state,
+system size and the spatial anisotropy. The oscillatory behavior is suppressed
+once the system is coupled to the environment. Furthermore, the asymptotic
+behavior of the entanglement, nearest neighbor and beyond, in the system under
+the influence of the environment at zero temperature is very sensitive to the
+x-y spatial anisotropy, which causes them to reach either a zero or a finite
+sustainable steady state value regardless of the initial state of the system.
+The anisotropy in the $z-$direction may enhance the entanglement depending on
+the interplay with the magnetic field applied in the same direction. As the
+temperature is raised, the steady state of the short range entanglements is
+found to be robust within very small non-zero temperature range, which depends
+critically on the spatial anisotropy of the system. The entanglement at each
+range depends differently on the spatial anisotropy. Moreover, the end to end
+entanglement transfer time and speed through the open boundary chain vary
+significantly based on the degree of anisotropy and the temperature of the
+environment.",1604.02689v1
+2016-07-18,Effects of Crystal Anisotropy on Optical Phonon Resonances in the Mid-Infrared Second Harmonic Response of SiC,"We study the effects of crystal anisotropy on optical phonon resonances in
+the second harmonic generation (SHG) from silicon carbide (SiC) in its
+Reststrahl region. By comparing experiments and simulations for isotropic
+3C-SiC and anisotropic 4H-SiC in two crystal cuts, we identify several
+pronounced effects in the nonlinear response which arise solely from the
+crystal anisotropy. Specifically, we demonstrate that the axial and planar
+transverse optical phonon resonances selectively and exclusively appear in the
+corresponding tensor elements of the nonlinear susceptibility, enabling
+observation of an intense SHG peak originating from a weak phonon mode due to
+zone-folding along the c-axis of 4H-SiC. Similarly, we identify an anisotropy
+factor $\zeta \equiv \epsilon_\perp/\epsilon_\parallel$ responsible for a steep
+enhancement of the transmitted fundamental fields at the axial longitudinal
+optical phonon frequency, resulting in strongly enhanced SHG. We develop a
+general recipe to extract all these features that is directly applicable to all
+wurtzite-structure polar dielectrics, where a very similar behavior is
+expected. Our model study illustrates the opportunities for utilizing the
+crystal anisotropy for selectively enhancing nonlinear-optical effects in polar
+dielectrics, which could potentially be extended to built-in anisotropy in
+artificially designed hybrid materials.",1607.05207v2
+2016-09-17,Magnetic-anisotropy induced spin blockade in a single-molecule transistor,"We present a new mechanism for a spin blockade effect associated with a
+change in the type of magnetic anisotropy over oxidation state in a single
+molecule transistor, by taking an example of an individual
+Eu$_{2}$(C$_{8}$H$_{8}$)$_{3}$ molecule weakly coupled to non-magnetic
+electrodes without linker groups. The molecule switches its magnetization
+direction from in-plane to out-of-plane when it is charged. In other words, the
+magnetic anisotropy of the molecule changes from easy plane to easy axis when
+the molecule is charged. By solving the master equation based on model
+Hamiltonian, we find that current through the molecule is highly suppressed at
+low bias independently of gate voltage due to the interplay between spin
+selection rules and the change in the type of magnetic anisotropy. Transitions
+between the lowest magnetic levels in successive charge states are forbidden
+because the magnetic levels differ by $|\Delta M| > 1/2$ due to the change in
+the type of magnetic anisotropy, although the total spins differ by $|\Delta
+S|=1/2$. This current suppression can be lifted by significant B field, and the
+threshold B field varies as a function of the field direction and the strength
+of magnetic anisotropy. The spin blockade effect shed light on switching the
+magnetization direction by non-spin-polarized current and on exploring effects
+of this property coupled to other molecular degrees of freedom.",1609.05269v1
+2016-11-17,Anisotropy induces non-Fermi-liquid behavior and nematic magnetic order in three-dimensional Luttinger semimetals,"We illuminate the intriguing role played by spatial anisotropy in
+three-dimensional Luttinger semimetals featuring quadratic band touching and
+long-range Coulomb interactions. We observe the anisotropy to be subject to an
+exceptionally slow renormalization group (RG) evolution so that it can be
+considered approximately constant when computing the impact of quantum
+fluctuations on the remaining couplings of the system. Using perturbative RG we
+then study the competition of all local short-range interactions that are
+generated from the long-range interactions for fixed anisotropy. Two main
+effects come to light for sufficiently strong anisotropy. First, the
+three-dimensional system features an Abrikosov non-Fermi liquid ground state.
+Second, there appear qualitatively new fixed points which describe quantum
+phase transitions into phases with nemagnetic orders - higher-rank tensor
+orders that break time-reversal symmetry, and thus have both nematic and
+magnetic character. In real materials these phases may be realized through
+sufficiently strong microscopic short-range interactions. On the pyrochlore
+lattice, the anisotropy-induced fixed points determine the onset of
+all-in-all-out or spin ice ordering of local magnetic moments of the electrons.",1611.05904v2
+2016-11-23,"Cubic anisotropy created by defects of ""random local anisotropy"" type, and phase diagram of the O(n) model","The expression for the cubic-type-anisotropy constant created by defects of
+""random local anisotropy"" type is derived. It is shown that the Imry-Ma theorem
+stating that in space dimensions d<4 the introduction of an arbitrarily small
+concentration of defects of the ""random local anisotropy"" type in a system with
+continuous symmetry of the n-component vector order parameter (O(n) model)
+leads to the long-range order collapse and to occurrence of a disordered state,
+is not true if an anisotropic distribution of the defect-induced random easy
+axes directions in the order parameter space creates a global effective
+anisotropy of the ""easy axis"" type. For a weakly anisotropic distribution of
+the easy axes, in space dimensions 2<d<4 there exists some critical defect
+concentration, when exceeded, the inhomogeneous Imry-Ma state can exist as an
+equilibrium one. At lower defect concentration the long-range order takes place
+in the system. For a strongly anisotropic distribution of the easy axes, the
+Imry-Ma state is suppressed completely and the long-range order state takes
+place at any defect concentration.",1611.07948v1
+2016-12-01,Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba$_{0.67}$K$_{0.33}$Fe$_{2}$As$_{2}$,"We use polarized inelastic neutron scattering to study the temperature and
+energy dependence of spin space anisotropies in the optimally hole-doped iron
+pnictide Ba$_{0.67}$K$_{0.33}$Fe$_{2}$As$_{2}$ ($T_{{\rm c}}=38$ K). In the
+superconducting state, while the high-energy part of the magnetic spectrum is
+nearly isotropic, the low-energy part displays a pronouced anisotropy,
+manifested by a $c$-axis polarized resonance. We also observe that the spin
+anisotropy in superconducting Ba$_{0.67}$K$_{0.33}$Fe$_{2}$As$_{2}$ extends to
+higher energies compared to electron-doped BaFe$_{2-x}TM_{x}$As$_{2}$ ($TM=$Co,
+Ni) and isovalent-doped BaFe$_{2}$As$_{1.4}$P$_{0.6}$, suggesting a connection
+between $T_{\rm c}$ and the energy scale of the spin anisotropy. In the normal
+state, the low-energy spin anisotropy for optimally hole- and electron-doped
+iron pnictides onset at temperatures similar to the temperatures at which the
+elastoresistance deviate from Curie-Weiss behavior, pointing to a possible
+connection between the two phenomena. Our results highlight the relevance of
+the spin-orbit coupling to the superconductivity of the iron pnictides.",1612.00379v2
+2017-01-07,Velocity Anisotropy in Self-Gravitating Molecular Clouds. I: Simulation,"The complex interplay between turbulence, magnetic fields, and self-gravity
+leads to the formation of molecular clouds out of the diffuse interstellar
+medium (ISM). One avenue of studying this interplay is by analyzing statistical
+features derived from observations, where the interpretation of these features
+is greatly facilitated by comparisons with numerical simulations. Here we focus
+on the statistical anisotropy present in synthetic maps of velocity centroid
+data, which we derive from three-dimensional magnetohydrodynamic simulations of
+a turbulent, magnetized, self-gravitating patch of ISM. We study how the
+orientation and magnitude of the velocity anisotropy correlate with the
+magnetic field and with the structures generated by gravitational collapse.
+  Motivated by recent observational constraints, our simulations focus on the
+supersonic (sonic Mach number $\mathcal{M} \approx 2 - 17$) but sub- to
+trans-alfvenic (alfvenic Mach number $\mathcal{M}_A \approx 0.2 - 1.2$)
+turbulence regime, and we consider clouds which are barely to mildly
+magnetically supercritical (mass-to-flux ratio equal to once or twice the
+critical value). Additionally we explore the impact of the turbulence driving
+mechanism (solenoidal or compressive) on the velocity anisotropy.
+  While we confirm previous findings that the velocity anisotropy generally
+aligns well with the plane-of-sky magnetic field, our inclusion of the effects
+of self-gravity reveals that in regions of higher column density, the velocity
+anisotropy may be destroyed or even reoriented to align with the
+gravitationally formed structures. We provide evidence that this effect is not
+necessarily due to the increase of $\mathcal{M}_A$ inside the high-density
+regions.",1701.01806v1
+2017-05-08,The influence of magnetic order on the magnetoresistance anisotropy of Fe$_{1+δ-x}$Cu$_{x}$Te,"We performed resistance measurements on Fe$_{1+\delta-x}$Cu$_{x}$Te with
+$x_{EDX}\leq 0.06$ in the presence of in-plane applied magnetic fields,
+revealing a resistance anisotropy that can be induced at a temperature far
+below the structural and magnetic zero-field transition temperatures. The
+observed resistance anisotropy strongly depends on the field orientation with
+respect to the crystallographic axes, as well as on the field-cooling history.
+Our results imply a correlation between the observed features and the
+low-temperature magnetic order. Hysteresis in the angle-dependence indicates a
+strong pinning of the magnetic order within a temperature range that varies
+with the Cu content. The resistance anisotropy vanishes at different
+temperatures depending on whether an external magnetic field or a remnant field
+is present: the closing temperature is higher in the presence of an external
+field. For $x_{EDX} = 0.06$ the resistance anisotropy closes above the
+structural transition, at the same temperature at which the zero-field
+short-range magnetic order disappears and the sample becomes paramagnetic. Thus
+we suggest that under an external magnetic field the resistance anisotropy
+mirrors the magnetic order parameter. We discuss similarities to nematic order
+observed in other iron pnictide materials.",1705.02849v1
+2018-01-11,Modeling the Oblique Spin Precession in Lateral Spin Valves for Accurate Determination of Spin Lifetime Anisotropy: Effect of Finite Contact Resistance and Channel Length,"The spin lifetime anisotropy is an important quantity for investigating the
+spin relaxation mechanisms in graphene and in heterostructures of
+two-dimensional materials. We generalize the diffusive spin transport equations
+of oblique spin precession in a lateral spin valve with finite contact
+resistance. This yields a method to determine the spin lifetime anisotropy
+ratio {\xi}={\tau}$_{\perp}$/{\tau}$_{\parallel}$, which is the ratio between
+lifetimes of spin polarized perpendicular and parallel to the graphene surface.
+By solving the steady-state Bloch equations, we show that the line-shape of the
+oblique spin precession signal can be described with six dimensionless
+parameters, which can be solved analytically. We demonstrate that the
+anisotropic spin precession characteristics can be strongly suppressed by
+contact induced spin relaxation originating from conductance mismatch between
+the channel material and electrodes. To extract the spin lifetime anisotropy
+ratio accurately, we develop a closed form equation that includes the effect of
+finite contact resistance. Furthermore, we demonstrate that in the high contact
+resistance regime, the minimum channel length required for accurately
+determining the spin lifetime anisotropy for a sufficiently low external
+magnetic field is only determined by the diffusion coefficient of the channel
+material, as opposed to the spin diffusion length. Our work provides an
+accurate model to extract the spin lifetime anisotropy ratio from the oblique
+spin precession measurement, and can be used to guide the device design for
+such measurements.",1801.03606v1
+2018-02-27,"3D Anisotropy of Solar Wind Turbulence, Tubes, or Ribbons?","We study the anisotropy with respect to the local magnetic field of turbulent
+magnetic fluctuations at magnetofluid scales in the solar wind. Previous
+measurements in the fast solar wind obtained axisymmetric anisotropy, despite
+that the analysis method allows nonaxisymmetric structures. These results are
+probably contaminated by the wind expansion that introduces another symmetry
+axis, namely, the radial direction, as indicated by recent numerical
+simulations. These simulations also show that while the expansion is strong,
+the principal fluctuations are in the plane perpendicular to the radial
+direction. Using this property, we separate 11 yr of Wind spacecraft data into
+two subsets characterized by strong and weak expansion and determine the
+corresponding turbulence anisotropy. Under strong expansion, the small-scale
+anisotropy is consistent with the Goldreich & Sridhar critical balance. As in
+previous works, when the radial symmetry axis is not eliminated, the turbulent
+structures are field-aligned tubes. Under weak expansion, we find 3D anisotropy
+predicted by the Boldyrev model, that is, turbulent structures are ribbons and
+not tubes. However, the very basis of the Boldyrev phenomenology, namely, a
+cross-helicity increasing at small scales, is not observed in the solar wind:
+the origin of the ribbon formation is unknown.",1802.09837v2
+2018-06-05,Observing small-scale $γ$-ray anisotropies with the Cherenkov Telescope Array,"Disentangling the composition of the diffuse gamma-ray background (DGRB) is a
+major challenge in gamma-ray astronomy. It is presumed that at the highest
+energies, the DGRB is dominated by relatively few, still unresolved point
+sources. This conjecture has recently been supported by the measurement of
+small-scale anisotropies in the DGRB by the Fermi Large Area Telescope (LAT) up
+to energies of 500 GeV. We show how such anisotropies can be searched for with
+the forthcoming Earth-bound Cherenkov Telescope Array (CTA) up to the TeV
+range. We investigate different observation modes to analyse CTA data for
+small-scale anisotropies and propose the projected extragalactic large-area sky
+survey as the most promising data set. Relying on an up-to-date model of the
+performance of the southern CTA, we find that CTA will be able to probe
+anisotropies in the DGRB from unresolved point sources at a relative amplitude
+of $C_{\rm P}^I/I^2_{\rm DGRB}\gtrsim 4\times 10^{-3}\,{\rm sr}$ at energies
+above 30 GeV and angular scales $\lesssim 1.5^{\circ}$. Such DGRB anisotropies
+have not yet been ruled out by the Fermi-LAT. The proposed analysis would
+primarily clarify the contribution from blazars and misaligned active galactic
+nuclei to the very-high-energy regime of the DGRB, as well as provide insight
+into dark matter annihilation in Galactic and extragalactic density structures.
+Finally, it constitutes a measurement with complementary systematic
+uncertainties compared to the Fermi-LAT.",1806.01839v2
+2018-11-28,Inverse Anisotropic Catalysis in Holographic QCD,"We investigate the effects of anisotropy on the chiral condensate in a
+holographic model of QCD with a fully backreacted quark sector at vanishing
+chemical potential. The high temperature deconfined phase is a neutral and
+anisotropic plasma showing different pressure gradients along different spatial
+directions, similar to the state produced in noncentral heavy-ion collisions.
+We find that the chiral transition occurs at a lower temperature in the
+presence of anisotropy. Equivalently, we find that anisotropy acts
+destructively on the chiral condensate near the transition temperature. These
+are precisely the same footprints as the ""inverse magnetic catalysis"" i.e. the
+destruction of the condensate with increasing magnetic field observed earlier
+on the lattice, in effective field theory models and in holography. Based on
+our findings we suggest, in accordance with the conjecture of [1], that the
+cause for the inverse magnetic catalysis may be the anisotropy caused by the
+presence of the magnetic field instead of the charge dynamics created by it. We
+conclude that the weakening of the chiral condensate due to anisotropy is more
+general than that due to a magnetic field and we coin the former ""inverse
+anisotropic catalysis"". Finally, we observe that any amount of anisotropy
+changes the IR physics substantially: the geometry is $\text{AdS}_4 \times
+\mathbb{R}$ up to small corrections, confinement is present only up to a
+certain scale, and the particles acquire finite widths.",1811.11724v3
+2018-12-06,CMB statistical isotropy confirmation at all scales using multipole vectors,"We present an efficient numerical code and conduct, for the first time, a
+null and model-independent CMB test of statistical isotropy using Multipole
+Vectors (MVs) at all scales. Because MVs are insensitive to the angular power
+spectrum $C_\ell$, our results are independent from the assumed cosmological
+model. We avoid a posteriori choices and use pre-defined ranges of scales
+$\ell\in[2,30]$, $\ell\in[2,600]$ and $\ell\in[2,1500]$ in our analyses. We
+find that all four masked Planck maps, from both 2015 and 2018 releases, are in
+agreement with statistical isotropy for $\ell\in[2,30]$, $\ell\in[2,600]$. For
+$\ell\in[2,1500]$ we detect anisotropies but this is indicative of simply the
+anisotropy in the noise: there is no anisotropy for $\ell < 1300$ and an
+increasing level of anisotropy at higher multipoles. Our findings of no
+large-scale anisotropies seem to be a consequence of avoiding \emph{a
+posteriori} statistics. We also find that the degree of anisotropy in the full
+sky (i.e. unmasked) maps vary enormously (between less than 5 and over 1000
+standard deviations) among the different mapmaking procedures and data
+releases.",1812.02654v5
+2018-12-08,Resolution-induced anisotropy in LES,"Large eddy simulation (LES) of turbulence in complex geometries and domains
+is often conducted with high aspect ratio resolution cells of varying shapes
+and orientations. The effects of such anisotropic resolution are often
+simplified or neglected in subgrid model formulation. Here, we examine
+resolution induced anisotropy and demonstrate that, even for isotropic
+turbulence, anisotropic resolution induces mild resolved Reynolds stress
+anisotropy and significant anisotropy in second-order resolved velocity
+gradient statistics. In large eddy simulations of homogeneous isotropic
+turbulence with anisotropic resolution, it is shown that commonly used subgrid
+models, including those that consider resolution anisotropy in their
+formulation, perform poorly. The one exception is the anisotropic minimum
+dissipation model proposed by Rozema et al. (Phys. of Fluids 27, 085107, 2015).
+A simple new model is presented here that is formulated with an anisotropic
+eddy diffusivity that depends explicitly on the anisotropy of the resolution.
+It also performs well, and is remarkable because unlike other LES subgrid
+models, the eddy diffusivity only depends on statistical characteristics of the
+turbulence (in this case the dissipation rate), not on fluctuating quantities.
+In other subgrid modeling formulations, such as the dynamic procedure, limiting
+flow dependence to statistical quantities in this way could have advantages.",1812.03261v2
+2019-01-04,Anisotropies and magnetic phase transitions in insulating antiferromagnets determined by a Spin-Hall magnetoresistance probe,"We demonstrate that we can determine the antiferromagnetic anisotropies and
+the bulk Dzyaloshinskii-Moriya fields of the insulating iron oxide hematite,
+{\alpha}-Fe2O3, using a surface sensitive spin-Hall magnetoresistance (SMR)
+technique. We develop an analytical model that in combination with SMR
+measurements, allow for the identification of the material parameters of this
+prototypical antiferromagnet over a wide range of temperatures and magnetic
+field values. Using devices with different orientations, we demonstrate that
+the SMR response strongly depends on the direction of the charge current with
+respect to the magneto-crystalline anisotropies axis. We show that we can
+extract the anisotropies over a wide temperature range including across the
+Morin phase transition. We observe that the electrical response is dominated by
+the orientation of the antiferromagnetic N\'eel order parameter, rather than by
+the emergent weak magnetic moment. Our results highlight that the surface
+sensitivity of the SMR allows accessing the magnetic anisotropies of
+antiferromagnetic crystals and in particular thin films where other methods to
+determine anisotropies such as bulk-sensitive magnetic susceptibility
+measurements do not provide sufficient sensitivity.",1901.01213v1
+2019-03-07,A Search for Cosmic-ray Proton Anisotropy with the Fermi Large Area Telescope,"The Fermi Large Area Telescope (LAT) has amassed a large data set of primary
+cosmic-ray protons throughout its mission. The LAT's wide field of view and
+full-sky survey capabilities make it an excellent instrument for studying
+cosmic-ray anisotropy. As a space-based survey instrument, the LAT is sensitive
+to anisotropy in both right ascension and declination, while ground-based
+observations only measure the anisotropy in right ascension. We present the
+results of the first ever proton anisotropy search using Fermi LAT. The data
+set uses eight years of data and consists of approximately 179 million protons
+above 78 GeV, enabling it to probe dipole anisotropy below an amplitude of
+$10^{-3}$, resulting in the most stringent limits on the declination dependence
+of the dipole to date. We measure a dipole amplitude $\delta = 3.9\pm1.5 \times
+10^{-4}$ with a p-value of 0.01 (pre-trials) for protons with a minimum energy
+of 78 GeV. We discuss various systematic effects that could give rise to a
+dipole excess and calculate upper limits on the dipole amplitude as a function
+of minimum energy. The 95% CL upper limit on the dipole amplitude is
+$\delta_{UL}=1.3\times 10^{-3}$ for protons with a minimum energy of 78 GeV and
+$\delta_{UL}=1.2 \times 10^{-3}$ for protons with a minimum energy of 251 GeV.",1903.02905v1
+2019-05-29,Anisotropies of different mass compositions of cosmic rays,"The spectral hardenings of cosmic ray nuclei above $\sim 200$ GV followed by
+softenings around 10 TV, the knee of the all-particle spectrum around PeV
+energies, as well as the pattern change of the amplitude and phase of the
+large-scale anisotropies around 100 TeV indicate the complexities of the origin
+and transportation of Galactic cosmic rays. It has been shown that nearby
+source(s) are most likely to be the cause of such spectral features of both the
+spectra and the anisotropies. In this work, we study the anisotropy features of
+different mass composition (or mass groups) of cosmic rays in this nearby
+source model. We show that even if the spectral features from the nearby source
+component is less distinctive compared with the background component from e.g.,
+the population of distant sources, the anisotropy features are more remarkable
+to be identified. Measurements of the anisotropies of each mass composition
+(group) of cosmic rays by the space experiments such as DAMPE and HERD and the
+ground-based experiments such as LHAASO in the near future are expected to be
+able to critically test this scenario.",1905.12505v3
+2019-07-19,Particle-In-Cell simulations of the parallel proton firehose instability influenced by the electron temperature anisotropy in solar wind conditions,"In situ observations of the solar wind show a limited level of particle
+temperature anisotropy with respect to the interplanetary magnetic field
+direction. Kinetic electromagnetic instabilities are efficient to prevent the
+excessive growth of the anisotropy of particle velocity distribution functions.
+Among them, the firehose instabilities are often considered to prevent the
+increase of the parallel temperature and hence to shape the velocity
+distribution functions of electrons and protons in the solar wind. We present a
+non-linear modeling of the parallel firehose instability, retaining a kinetic
+description for both the electrons and protons. One-dimensional (1D) fully
+kinetic Particle-In-Cell simulations using the Energy Conserving semi-implicit
+method (ECsim) are performed to clarify the role of the electron temperature
+anisotropy in the development of the parallel proton firehose instability. We
+found that in the presence of an electron temperature anisotropy, such that the
+temperature parallel to the background magnetic field is higher than the
+temperature in the perpendicular direction, the onset of the parallel proton
+firehose instability occurs earlier and its growth rate is faster. The enhanced
+wave fluctuations contribute to the particle scattering reducing the
+temperature anisotropy to a stable, nearly isotropic state. The simulation
+results compare well with linear theory. A test case of 1D simulations at
+oblique angles with respect to the magnetic field is also considered, as a
+first step to study the cumulative effect of protons and electrons on the full
+spectrum of instabilities.",1907.08502v2
+2019-08-17,Hybrid Color Glass Condensate and hydrodynamic description of the Relativistic Heavy Ion Collider small system scan,"Multi-particle correlation observables in the Relativistic Heavy Ion Collider
+small system scan are computed in a framework that contains both initial state
+momentum anisotropies from the Color Glass Condensate effective theory and
+final state hydrodynamic evolution. The initial state is computed using the
+IP-Glasma model and coupled to viscous relativistic hydrodynamic simulations,
+which are followed by microscopic hadronic transport. All parameters of the
+calculation were previously constrained using experimental data on Au+Au
+collisions at the same center of mass energy. We find that the qualitative
+features of the experimental data, such as the system and centrality dependence
+of the charged hadron momentum anisotropy, can only be reproduced when final
+state interactions are present. On the other hand, we also demonstrate that the
+details of the initial state are crucially important for the quantitative
+description of observables in the studied small systems, as neglecting the
+initial transverse flow profile or the initial shear stress tensor, which
+contain information on the momentum anisotropy from the Color Glass Condensate,
+has dramatic effects on the produced final state anisotropy. We further show
+that the initial state momentum anisotropy is correlated with the observed
+elliptic flow in all small systems, with the effect increasing with decreasing
+multiplicity. We identify the precise measurement of $v_2$ in d+Au and Au+Au
+collisions at RHIC energy at the same multiplicity as a means to reveal effects
+of the initial state momentum anisotropy.",1908.06212v1
+2019-10-30,Transverse momentum and process dependent azimuthal anisotropies in $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV $p$+Pb collisions with the ATLAS detector,"The azimuthal anisotropy of charged particles produced in
+$\sqrt{s_{\mathrm{NN}}}=8.16$ TeV $p$+Pb collisions is measured with the ATLAS
+detector at the LHC. The data correspond to an integrated luminosity of $165$
+$\mathrm{nb}^{-1}$ that was collected in 2016. Azimuthal anisotropy
+coefficients, elliptic $v_2$ and triangular $v_3$, extracted using two-particle
+correlations with a non-flow template fit procedure, are presented as a
+function of particle transverse momentum ($p_\mathrm{T}$) between $0.5$ and
+$50$ GeV. The $v_2$ results are also reported as a function of centrality in
+three different particle $p_\mathrm{T}$ intervals. The results are reported
+from minimum-bias events and jet-triggered events, where two jet $p_\mathrm{T}$
+thresholds are used. The anisotropies for particles with $p_\mathrm{T}$ less
+than about $2$ GeV are consistent with hydrodynamic flow expectations, while
+the significant non-zero anisotropies for $p_\mathrm{T}$ in the range $9$-$50$
+GeV are not explained within current theoretical frameworks. In the
+$p_\mathrm{T}$ range $2$-$9$ GeV, the anisotropies are larger in minimum-bias
+than in jet-triggered events. Possible origins of these effects, such as the
+changing admixture of particles from hard scattering and the underlying event,
+are discussed.",1910.13978v2
+2019-12-21,Extreme acoustic anisotropy in crystals visualized by diffraction tensor,"Acoustic wave propagation in single crystals, metamaterials and composite
+structures is a basic mechanism in acoustic, acousto-electronic and
+acousto-optic devices. Acoustic anisotropy of crystals provides a variety of
+device performances and application fields, but its role in pre-estimation of
+achievable device characteristics and location of crystal orientations with
+desired properties is often underestimated. A geometrical image of acoustic
+anisotropy can be an important tool in design of devices based on wave
+propagation in single crystals or combinations of anisotropic materials. We
+propose a fast and robust method for survey and visualization of acoustic
+anisotropy based on calculation of the eigenvalues of bulk acoustic wave (BAW)
+diffraction tensor (curvature of the slowness surface). The stereographic
+projection of these eigenvalues clearly reveals singular directions of BAW
+propagation (acoustic axes) in anisotropic media and areas of fast or slow
+variation of wave velocities. The method is illustrated by application to three
+crystals of different symmetry used in different types of acoustic devices:
+paratellurite, lithium niobate, and potassium gadolinium tungstate. The
+specific features of acoustic anisotropy are discussed for each crystal in
+terms of their potential application in devices. In addition, we demonstrate
+that visualization of acoustic anisotropy of lithium niobate helps to find
+orientations supporting propagation of high-velocity surface acoustic waves.",1912.10270v1
+2020-02-25,Strain-Tuned Magnetic Anisotropy in Sputtered Thulium Iron Garnet Ultrathin Films and TIG/Au/TIG Valve Structures,"Defining the magnetic anisotropy for in-plane or out-of-plane easy axis in
+ferrimagnetic insulators films by controlling the strain, while maintaining
+high-quality surfaces, is desirable for spintronic and magnonic applications.
+We investigate ways to tune the anisotropy of amorphous sputtered ultrathin
+thulium iron garnet (TIG) films, and thus tailor their magnetic properties by
+the thickness (7.5 to 60 nm), substrate choice (GGG and SGGG), and
+crystallization process. We correlate morphological and structural properties
+with the magnetic anisotropy of post-growth annealed films. 30 nm thick films
+annealed at 600 {\deg}C show compressive strain favoring an in-plane magnetic
+anisotropy (IPMA), whereas films annealed above 800 {\deg}C are under a tensile
+strain leading to a perpendicular magnetic anisotropy (PMA). Air-annealed films
+present a high degree of crystallinity and magnetization saturation close to
+the bulk value. These results lead to successful fabrication of trilayers
+TIG/Au/TIG, with coupling between the TIG layers depending on Au thickness.
+These results will facilitate the use of TIG to create various in situ clean
+hybrid structures for fundamental interface exchange studies, and towards the
+development of complex devices. Moreover, the sputtering technique is
+advantageous as it can be easily scaled up for industrial applications.",2002.10608v2
+2020-06-28,Observable signatures of initial state momentum anisotropies in nuclear collisions,"We show that the correlation between the elliptic momentum anisotropy, $v_2$,
+and the average transverse momentum, $[p_T]$, at fixed multiplicity in small
+system nuclear collisions carries information on the origin of the observed
+momentum anisotropy. A calculation using a hybrid
+IP-Glasma+\textsc{Music}+UrQMD model that includes contributions from final
+state response to the initial geometry as well as initial state momentum
+anisotropies of the Color Glass Condensate, predicts a characteristic sign
+change of the correlator $\hat{\rho}(v_2^2,[p_T])$ as a function of charged
+particle multiplicity in p+Au and d+Au collisions at $\sqrt{s}=200\,{\rm GeV}$,
+and p+Pb collisions at $\sqrt{s}=5.02\,{\rm TeV}$. This sign change is absent
+in calculations without initial state momentum anisotropies. The model further
+predicts a qualitative difference between the centrality dependence of
+$\hat{\rho}(v_2^2,[p_T])$ in Au+Au collisions at $\sqrt{s}=200\,{\rm GeV}$ and
+Pb+Pb collisions at $\sqrt{s}=5.02\,{\rm TeV}$, with only the latter showing a
+sign change in peripheral events. Predictions for O+O collisions at different
+collision energy show a similar behavior. Experimental observation of these
+distinct qualitative features of $\hat{\rho}(v_2^2,[p_T])$ in small and large
+systems would constitute strong evidence for the presence and importance of
+initial state momentum anisotropies predicted by the Color Glass Condensate
+effective theory.",2006.15721v1
+2020-07-22,Study of magnetization relaxation in molecular spin clusters using an innovative kinetic Monte Carlo method,"Modeling blocking temperature in molecular magnets has been a long standing
+problem in the field of molecular magnetism. We investigate this problem using
+a kinetic Monte Carlo (kMC) approach on an assembly of 100,000 short molecular
+magnetic chains (SMMCs), each of six identical spins with nearest neighbour
+anisotropic ferromagnetic exchange interactions. Each spin is also anisotropic
+with an uniaxial anisotropy. The site spin on these SMMCs take values $1$,
+$3/2$ or $2$. Using eigenstates of these SMMCs as the states of Markov chain,
+we carry out a kMC simulation starting with an initial state in which all SMMCs
+are completely spin polarized and assembled on a one-dimensional lattice so as
+to experience ferromagnetic spin-dipolar interaction with each other. From
+these simulations we obtain the relaxation time $\tau_r$ as a function of
+temperature and the associated blocking temperature. We study this for
+different exchange anisotropy, on-site anisotropy and strength of dipolar
+interactions. The magnetization relaxation times show non-Arrhenius behaviour
+for weak on-site interactions. The energy barrier to magnetization relaxation
+increases with increase in on-site anisotropy, exchange anisotropy and strength
+of spin dipolar interactions; more strongly on the last parameter. In all cases
+the barrier saturates at large on-site anisotropy. The barrier also increases
+with site spin. The large barrier observed in rare-earth single ion magnets can
+be attributed to large dipolar interactions due to short intermolecular
+distances, owing to their small size and large spin of the rare earth ion in
+the molecule.",2007.11342v4
+2020-08-28,Testing cosmic anisotropy with Pantheon sample and quasars at high redshifts,"In this paper, we investigate the cosmic anisotropy from the SN-Q sample,
+consisting of the Pantheon sample and quasars, by employing the hemisphere
+comparison (HC) method and the dipole fitting (DF) method. Compared to the
+Pantheon sample, the new sample has a larger redshift range, a more homogeneous
+distribution, and a larger sample size. For the HC method, we find that the
+maximum anisotropy level is $AL_{max}=0.142\pm0.026$ in the direction ($l$,
+$b$) = $({316.08^{\circ}}^{+27.41}_{-129.48}$,
+${4.53^{\circ}}^{+26.29}_{-64.06})$. The magnitude of anisotropy is $A$ =
+($-$8.46 $^{+4.34}_{-5.51}$)$\times$$10^{-4}$ and the corresponding preferred
+direction points toward $(l$, $b)$ = ($29.31^{\circ}$$^{+30.59}_{-30.54}$,
+$71.40^{\circ}$$^{+9.79}_{-9.72}$) for the quasar sample from the DF method.
+The combined SN and quasar sample is consistent with the isotropy hypothesis.
+The distribution of the dataset might impact the preferred direction from the
+dipole results. The result is weakly dependent on the redshift from the
+redshift tomography analysis. There is no evidence of cosmic anisotropy in the
+SN-Q sample. Though some results obtained from the quasar sample are not
+consistent with the standard cosmological model, we still do not find any
+distinct evidence of cosmic anisotropy in the SN-Q sample.",2008.12439v1
+2020-09-18,The effect of the surface magnetic anisotropy of the neodymium atoms on the coercivity in the neodymium permanent magnet,"The Nd permanent magnet (Nd$_{2}$Fe$_{14}$B) is an indispensable material
+used in modern energy conversion devices. The realization of high coercivity at
+finite temperatures is a burning issue. One of the important ingredients for
+controlling the coercive force is the surface property of magnetic grains. It
+has been reported by first-principles studies that the Nd atoms in the first
+(001) surface layer facing the vacuum have in-plane anisotropy perpendicular to
+the $c$ axis, which may decrease the coercivity. Focusing on the surface
+anisotropy effect on the coercivity, we examine the coercivity at zero and
+finite temperatures by using an atomistic model reflecting the lattice
+structure of the Nd magnet with a stochastic Landau-Lifshitz-Gilbert equation
+method. We study general three cases, in which the Nd atoms in surface layers
+have (1) no anisotropy, (2) in-plane anisotropy, and (3) reinforced anisotropy
+for two types of surfaces, (001) and (100) surfaces. We find that in contrast
+to the zero-temperature case, due to the thermal fluctuation effect, the
+modification of only the first surface layer has little effect on the
+coercivity at finite temperatures. However, the modification of a few layers
+results in significant effects. We discuss the details of the dependence of the
+coercivity on temperature, type of surface, and modified layer depth, and also
+the features of domain growth in magnetization reversal.",2009.08572v1
+2020-10-16,"Physical Explanation for the Galaxy Distribution on the $(λ_{\rm R}, \varepsilon)$ and $(V/σ, \varepsilon)$ Diagrams or for the Limit on Orbital Anisotropy","In the $(\lambda_{\rm R}, \varepsilon)$ and $(V/\sigma, \varepsilon)$
+diagrams for characterizing dynamical states, the fast-rotator galaxies (both
+early-type and spirals) are distributed within a well-defined leaf-shaped
+envelope. This was explained as due to an upper limit to the orbital anisotropy
+increasing with galaxy intrinsic flattening. However, a physical explanation
+for this empirical trend was missing. Here we construct Jeans Anisotropic
+Models (JAM), with either cylindrically or spherically aligned velocity
+ellipsoid (two extreme assumptions), and each with either spatially-constant or
+-variable anisotropy. We use JAM to build mock samples of axisymmetric
+galaxies, assuming on average an oblate shape for the velocity ellipsoid (as
+required to reproduce the rotation of real galaxies), and limiting the radial
+anisotropy $\beta$ to the range allowed by physical solutions. We find that all
+four mock samples naturally predict the observed galaxy distribution on the
+$(\lambda_{\rm R}, \varepsilon)$ and $(V/\sigma, \varepsilon)$ diagrams,
+without further assumptions. Given the similarity of the results from quite
+different models, we conclude that the empirical anisotropy upper limit in real
+galaxies, and the corresponding observed distributions in the $(\lambda_{\rm
+R}, \varepsilon)$ and $(V/\sigma, \varepsilon)$ diagrams, are due to the lack
+of physical axisymmetric equilibrium solutions at high $\beta$ anisotropy when
+the velocity ellipsoid is close to oblate.",2010.08586v1
+2020-10-20,The primordial information content of Rayleigh Anisotropies,"Anisotropies in the cosmic microwave background (CMB) are primarily generated
+by Thomson scattering of photons by free electrons. Around recombination, the
+Thomson scattering probability quickly diminishes as the free electrons combine
+with protons to form neutral hydrogen off which CMB photons can scatter through
+Rayleigh scattering. Unlike Thomson scattering, Rayleigh scattering is
+frequency dependent resulting in the generation of anisotropies with a
+different spectral dependence. Unfortunately the Rayleigh scattering efficiency
+rapidly decreases with the expansion of the neutral universe, with the result
+that only a small percentage of photons are scattered by neutral hydrogen.
+Although the effect is very small, future CMB missions with higher sensitivity
+and improved frequency coverage are poised to measure Rayleigh scattering
+signal. The uncorrelated component of the Rayleigh anisotropies contains unique
+information on the primordial perturbations that could potentially be leveraged
+to expand our knowledge of the early universe. In this paper we explore whether
+measurements of Rayleigh scattering anisotropies can be used to constrain
+primordial non-Gaussianity (NG) and examine the hints of anomalies found by
+WMAP and \textit{Planck} satellites. We show that the additional Rayleigh
+information has the potential to improve primordial NG constraints by $30\%$,
+or more. Primordial bispectra that are not of the local type benefit the most
+from these additional scatterings, which we attribute to the different scale
+dependence of the Rayleigh anisotropies. Unfortunately this different scaling
+means that Rayleigh measurements can not be used to constrain anomalies or
+features on large scales. On the other hand, anomalies that may persist to
+smaller scales, such as the potential power asymmetry seen in WMAP and
+\textit{Planck}, could be improved by the addition of Rayleigh measurements.",2010.10481v1
+2020-11-10,Frictional anisotropy of 3D-printed fault surfaces,"The surface morphology of faults controls the spatial anisotropy of their
+frictional properties, and hence their mechanical stability. Such anisotropy is
+only rarely studied in seismology models of fault slip, although it might be
+paramount to understand the seismic rupture in particular areas, notably where
+slip occurs in a direction different from that of the main striations of the
+fault. To quantify how the anisotropy of fault surfaces affects the friction
+coefficient during sliding, we sheared synthetic fault planes made of plaster
+of Paris. These fault planes were produced by 3D-printing real striated fault
+surfaces whose 3D roughness was measured in the field at spatial scales from
+millimeters to meters. Here, we show how the 3D-printing technology can help
+for the study of frictional slip. Results show that fault anisotropy controls
+the coefficient of static friction, with the friction coefficient along the
+striations being three to four times smaller than the friction coefficient
+along the direction perpendicular to the striations. This is true both at the
+meter and the millimeter scales. The anisotropy in friction and the average
+coefficient of static friction are also shown to decrease with the normal
+stress applied to the faults, as a result of the increased surface wear under
+increased loading.",2011.05012v2
+2020-12-16,A tool to predict coercivity in magnetic materials,"Magnetic coercivity is often viewed to be lower in alloys with negligible (or
+zero) values of the anisotropy constant. However, this explains little about
+the dramatic drop in coercivity in FeNi alloys at a non-zero anisotropy value.
+Here, we develop a theoretical and computational tool to investigate the
+fundamental interplay between material constants that govern coercivity in bulk
+magnetic alloys. The two distinguishing features of our coercivity tool are
+that: (a) we introduce a large localized disturbance, such as a spike-like
+magnetic domain, that provides a nucleation barrier for magnetization reversal;
+and (b) we account for magneto-elastic energy -- however small -- in addition
+to the anisotropy and magnetostatic energy terms. We apply this coercivity tool
+to show that the interactions between local instabilities and material
+constants, such as anisotropy and magnetostriction constants, are key factors
+that govern magnetic coercivity in bulk alloys. Using our model, we show that
+coercivity is minimum at the permalloy composition (Fe-21.5Ni-78.5) at which
+the alloy's anisotropy constant is not zero. We systematically vary the values
+of the anisotropy and magnetostriction constants, around the permalloy
+composition, and identify new combinations of material constants at which
+coercivity is small. More broadly, our coercivity tool provides a theoretical
+framework to potentially discover novel magnetic materials with low coercivity.",2012.09320v1
+2021-01-08,"Stability, Evolution and Switching of Ferroelectric Domain Structures in Lead-free BaZr$_{0.2}$Ti$_{0.8}$O$_3$-Ba$_{0.7}$Ca$_{0.3}$TiO$_3$ System: Thermodynamic Analysis and Phase-field Simulations","Enhanced room-temperature electromechanical coupling in the lead-free
+ferroelectric system $(1-x)$BaZr$_{0.2}$Ti$_{0.8}$O$_{3}$ -
+$x$Ba$_{0.7}$Ca$_{0.3}$TiO$_{3}$ (abbreviated as BZCT) at $x=0.5$ is attributed
+to the existence of a morphotropic phase region (MPR) containing an
+intermediate orthorhombic ($O$) phase between terminal rhombohedral ($R$) BZT
+and tetragonal ($T$) BCT phases. However, there is ambiguity regarding the
+morphotropic phase transition in BZCT at room temperature - while some
+experiments suggest a single $O$ phase within the MPR, others indicate
+coexistence of three polar phases ($T+R+O$). Therefore, to understand the
+thermodynamic stability of polar phases and its relation to electromechanical
+switching during morphotropic phase transition in BZCT, we develop a Landau
+potential based on the theory of polar anisotropy. Since intrinsic
+electrostrictive anisotropy changes as a function of electromechanical
+processing, we establish a correlation between the parameters of our potential
+and the coefficients of electrostriction. We also conducted phase-field
+simulations based on this potential to demonstrate changes in domain
+configuration from single-phase $O$ to three-phase $T+R+O$ at the equimolar
+composition with the increase in electrostrictive anisotropy. Diffusionless
+phase diagrams and the corresponding piezoelectric coefficients obtained from
+our model compare well with the experimental findings. Increase in
+electrostrictive anisotropy increases the degeneracy of the free energy at
+ambient temperature and pressure leading to decreasing polar anisotropy,
+although there is an accompanying increase in the electromechanical anisotropy
+manifested by an increase in the difference between effective longitudinal and
+transverse piezo-coefficients, $d_{33}$ and $d_{31}$.",2101.03066v1
+2021-02-26,Anisotropy of Solar-Wind Turbulence in the Inner Heliosphere at Kinetic Scales: PSP Observations,"The anisotropy of solar wind turbulence is a critical issue in understanding
+the physics of energy transfer between scales and energy conversion between
+fields and particles in the heliosphere. Using the measurement of \emph{Parker
+Solar Probe} (\emph{PSP}), we present an observation of the anisotropy at
+kinetic scales in the slow, Alfv\'enic, solar wind in the inner heliosphere.
+\textbf{The magnetic compressibility behaves as expected for kinetic Alfv\'enic
+turbulence below the ion scale.} A steepened transition range is found between
+the inertial and kinetic ranges in all directions with respect to the local
+background magnetic field direction. The anisotropy of $k_\perp \gg
+k_\parallel$ is found evident in both transition and kinetic ranges, with the
+power anisotropy $P_\perp/P_\parallel > 10$ in the kinetic range leading over
+that in the transition range and being stronger than that at 1 au. The spectral
+index varies from $\alpha_{t\parallel}=-5.7\pm 1.0$ to $\alpha_{t\perp}=-3.7\pm
+0.3$ in the transition range and $\alpha_{k\parallel}=-3.12\pm 0.22$ to
+$\alpha_{k\perp}=-2.57\pm 0.09$ in the kinetic range. The corresponding
+wavevector anisotropy has the scaling of $k_\parallel \sim k_\perp^{0.71\pm
+0.17}$ in the transition range, and changes to $k_\parallel \sim
+k_\perp^{0.38\pm 0.09}$ in the kinetic range, consistent with the kinetic
+Alfv\'enic turbulence at sub-ion scales.",2102.13294v2
+2021-03-04,WawHelioGlow: a model of the heliospheric backscatter glow. II. The helioglow buildup and the potential significance of the anisotropy in the solar EUV output,"The helioglow is a fluorescence of interstellar atoms inside the heliosphere,
+where they are excited by the solar EUV. Because the mean free path between
+collisions for the interstellar gas is comparable to the size of the
+heliosphere, the distribution function of this gas inside the heliosphere
+strongly varies in space and with time and is non-Maxwellian. Coupling between
+realistically modeled solar factors and the distribution function of
+interstellar neutral gas is accounted for in a helioglow model that we have
+developed. WawHelioGlow is presented in the accompanying Paper I. Here, we
+present the evolution of the gas density, solar illumination, helioglow source
+function, and other relevant parameters building up the helioglow signal for
+selected lines of sight observed at 1 au. We compare these elements for various
+phases of the solar cycle and we present the sensitivity of the results to
+heliolatitudinal anisotropy of the solar EUV output. We assume a realistic
+latitudinal anisotropy of the solar wind flux using results from analysis of
+interplanetary scintillations. We compare the simulated helioglow with with
+selected maps observed by the SOHO/SWAN instrument. We demonstrate that
+WawHelioGlow is able to reproduce fundamental features of the sky distribution
+of the helioglow. For some phases of the solar cycle, the model with an
+anisotropy of the solar EUV output better reproduces the observations, while
+for other phases no EUV anisotropy is needed. In all simulated cases, the solar
+wind anisotropy following insight from interplanetary scintillation
+measurements is present.",2103.02802v1
+2021-05-01,Anisotropy and Current Control of Magnetization in SrRuO$_3$ SrTiO$_3$ Heterostructures for Spin-Memristors,"Spintronics-based nonvolatile components in neuromorphic circuits offer the
+possibility of realizing novel functionalities at low power. Current-controlled
+electrical switching of magnetization is actively researched in this context.
+Complex oxide heterostructures with perpendicular magnetic anisotropy (PMA),
+consisting of SrRuO$_3$ (SRO) grown on SrTiO$_3$ (STO) are strong material
+contenders. Utilizing the crystal orientation, magnetic anisotropy in such
+simple heterostructures can be tuned to either exhibit a perfect or slightly
+tilted PMA. Here, we investigate current-induced magnetization modulation in
+such tailored ferromagnetic layers with a material with strong spin-orbit
+coupling (Pt), exploiting the spin Hall effect. We find significant differences
+in the magnetic anisotropy between the SRO/STO heterostructures, as manifested
+in the first and second harmonic magnetoresistance measurements.
+Current-induced magnetization switching can be realized with spin-orbit
+torques, but for systems with perfect PMA this switching is probabilistic as a
+result of the high symmetry. Slight tilting of the PMA can break this symmetry
+and allow the realization of deterministic switching. Control over the magnetic
+anisotropy of our heterostructures therefore provides control over the manner
+of switching. Based on our findings, we propose a three-terminal spintronic
+memristor, with a magnetic tunnel junction design, that shows several resistive
+states controlled by electric charge. Non-volatile states can be written
+through SOT by applying an in-plane current, and read out as a tunnel current
+by applying a small out-of-plane current. Depending on the anisotropy of the
+SRO layer, the writing mechanism is either deterministic or probabilistic
+allowing for different functionalities to emerge. We envisage that the
+probabilistic MTJs could be used as synapses while the deterministic devices
+can emulate neurons",2105.00269v1
+2021-05-05,Superconductivity assisted change of the perpendicular magnetic anisotropy in V/MgO/Fe junctions,"Controlling the perpendicular magnetic anisotropy (PMA) in thin films has
+received considerable attention in recent years due to its technological
+importance. PMA based devices usually involve heavy-metal
+(oxide)/ferromagnetic-metal bilayers, where, thanks to interfacial spin-orbit
+coupling (SOC), the in-plane (IP) stability of the magnetization is broken.
+Here we show that in V/MgO/Fe(001) epitaxial junctions with competing in-plane
+and out-of-plane (OOP) magnetic anisotropies, the SOC mediated interaction
+between a ferromagnet (FM) and a superconductor (SC) enhances the effective PMA
+below the superconducting transition. This produces a partial magnetization
+reorientation without any applied field for all but the largest junctions,
+where the IP anisotropy is more robust; for the smallest junctions there is a
+reduction of the field required to induce a complete OOP transition
+($H_\text{OOP}$) due to the stronger competition between the IP and OOP
+anisotropies. Our results suggest that the degree of effective PMA could be
+controlled by the junction lateral size in the presence of superconductivity
+and an applied electric field. We also discuss how the $H_\text{OOP}$ field
+could be affected by the interaction between magnetic stray fields and
+superconducting vortices. Our experimental findings, supported by numerical
+modelling of the ferromagnet-superconductor interaction, open pathways to
+active control of magnetic anisotropy in the emerging dissipation-free
+superconducting spin electronics.",2105.02050v4
+2021-05-17,On the Temperature-dependent Characteristics of Perpendicular Shape Anisotropy-Spin Transfer Torque-Magnetic Random Access Memories (PSA-STT-MRAMs),"The perpendicular shape anisotropy-spin transfer torque-magnetic random
+access memories (PSASTT-MRAMs) takes advantage of the nanopillar free-layer
+geometry for securing a good thermal stability factor from the shape anisotropy
+of the nanomagnet. Such a concept is particularly well-suited for small
+junctions down to a few nanometers. At such a volume size, the nanopillar can
+be effectively modeled as a Stoner-Wohlfarth (SW) particle, and the shape
+anisotropy scales with the spontaneous magnetization by ~ Ms^2. For almost all
+ferromagnets, Ms is a strong function of temperature, therefore, the
+temperature-dependent shape anisotropy is an important factor to be considered
+in any modeling of the temperature-dependent performance of PSA-STT-MRAMs. In
+this work, we summarize and discuss various possible temperature-dependent
+contributions to the thermal stability factor and coercivity of the
+PSA-STT-MRAMs by modeling and comparing different temperature scaling and
+parameters. We reveal nontrivial corrections to the thermal stability factor by
+considering both temperature-dependent shape and interfacial anisotropies. The
+coercivity, blocking temperature, and electrical switching characteristics that
+resulted from incorporating such a temperature dependence are also discussed,
+in conjugation with the nanomagnet dimension and coherence volume.",2105.07801v1
+2021-08-27,Effects of anisotropy on strongly magnetized neutron and strange quark stars in general relativity,"We investigate the properties of anisotropic, spherically symmetric compact
+stars, especially neutron stars and strange quark stars, made of strongly
+magnetized matter. The neutron stars are described by SLy equation of state,
+the strange quark stars by an equation of state based on the MIT Bag model. The
+stellar models are based on an a priori assumed density dependence of the
+magnetic field and thus anisotropy. Our study shows that not only the presence
+of a strong magnetic field and anisotropy, but also the orientation of the
+magnetic field itself, have an important influence on the physical properties
+of stars. Two possible magnetic field orientations are considered, a radial
+orientation, where the local magnetic fields point in the radial direction, and
+a transverse orientation, where the local magnetic fields are perpendicular to
+the radial direction. Interestingly, we find that for a transverse orientation
+of the magnetic field, the stars become more massive with increasing anisotropy
+and magnetic field strength and increase in size, since the repulsive,
+effective anisotropic force increases in this case. In the case of a radially
+orientated magnetic field, however, the masses and radii of the stars decrease
+with increasing magnetic field strength, because of the decreasing effective
+anisotropic force. Importantly, we also show that in order to achieve
+hydrostatic equilibrium configurations of magnetized matter, it is essential to
+account for both the local anisotropy effects as well as the anisotropy effects
+caused by a strong magnetic field. Otherwise, hydrostatic equilibrium is not
+achieved for magnetized stellar models.",2108.12436v1
+2021-11-08,Anisotropy and quench dynamics of quasiholes in fractional quantum Hall liquids,"We present a microscopic study of quasiholes in bosonic fractional quantum
+Hall (FQH) liquids at filling factor $\nu=1/2$ in the lowest Landau level with
+anisotropic band mass tensors. We use the spatial density profile to
+characterize the shape of a quasihole and analyze its anisotropy. We then
+compare the quasihole's anisotropy with the intrinsic geometric metric of the
+system that is extracted from the maximal overlap between the numerically
+obtained quasihole ground state and a set of model wave functions of
+anisotropic quasiholes. For a static system, we find that the quasihole's
+anisotropy, similar to the intrinsic metric, grows with the anisotropy of the
+band mass tensor. When the quasihole develops well, we observe a correspondence
+between the anisotropy of the quasihole and the intrinsic metric of the
+underlying anisotropic FQH state. We also drive the system out of equilibrium
+by suddenly changing the band mass tensor. In this case, the shape of the
+quasihole evolves with time and shows similar dynamics with the intrinsic
+metric of the postquench state. The evolving frequency matches the energy of a
+spin-$2$ quadrupole degree of freedom in the system. Our results suggest that
+the density profile of a quasihole is a useful tool to estimate the intrinsic
+metric and capture the dynamics of an FQH system.",2111.04214v2
+2022-01-06,Impact of Warm Dark Matter on the Cosmic Neutrino Background Anisotropies,"The Cosmic Neutrino Background (C$\nu$B) anisotropies for massive neutrinos
+are a unique probe of large-scale structure formation. The redshift-distance
+measure is completely different for massive neutrinos as compared to
+electromagnetic radiation. The C$\nu$B anisotropies in massive neutrinos grow
+in response to non-relativistic motion in gravitational potentials seeded by
+relatively high $k$-modes. Differences in the early phases of large-scale
+structure formation in Warm Dark Matter (WDM) versus Cold Dark Matter (CDM)
+cosmologies have an impact on the magnitude of the C$\nu$B anisotropies for
+contributions to the angular power spectrum that peak at high $k$-modes. We
+take the examples of WDM consisting of 2, 3 or 7 keV sterile neutrinos and show
+that the C$\nu$B anisotropies for 0.05 eV neutrinos drop off at high-$l$
+multipole moment in the angular power spectrum relative to CDM. At the same
+angular scales that one can observe baryonic acoustical oscillations in the
+CMB, the C$\nu$B anisotropies begin to become sensitive to differences in WDM
+and CDM cosmologies. The precision measurement of high-$l$ multipoles in the
+C$\nu$B neutrino sky map is a potential possibility for the PTOLEMY experiment
+with thin film targets of spin-polarized atomic tritium superfluid that exhibit
+significant quantum liquid amplification for non-relativistic relic neutrino
+capture.",2201.01888v2
+2022-02-08,Tunable Magnetic Anisotropy in Patterned SrRuO3 Quantum Structures: Competition between Lattice Anisotropy and Oxygen Octahedral Rotation,"Artificial perovskite-oxide nanostructures possess intriguing magnetic
+properties due to their tailorable electron-electron interactions, which are
+extremely sensitive to the oxygen coordination environment. To date,
+perovskite-oxide nanodots with sizes below 50 nm have rarely been reported.
+Furthermore, the oxygen octahedral distortion and its relation to magnetic
+properties in perovskite oxide nanodots remain unexplored yet. Here, we have
+studied the magnetic anisotropy in patterned SrRuO3 (SRO) nanodots as small as
+30 nm while performing atomic-resolution electron microscopy and spectroscopy
+to directly visualize the constituent elements, in particular oxygen ions. We
+observe that the magnetic anisotropy and RuO6 octahedra distortion in SRO
+nanodots are both nanodots' size-dependent but remain unchanged in the first
+3-unit-cell interfacial SRO monolayers regardless of the dots' size. Combined
+with the first principle calculations, we unravel a unique structural mechanism
+behind the nanodots' size-dependent magnetic anisotropy in SRO nanodots,
+sugguesting that the competition between lattice anisotropy and oxygen
+octahedral rotation mediates anisotropic exchange interactions in SRO nanodots.
+These findings demonstrate a new avenue towards tuning magnetic properties of
+correlated perovskite oxides and imply that patterned nanodots could be a
+promising playground for engineering emergent functional behaviors.",2202.03820v1
+2022-05-13,Isotropic orbital magnetic moments in magnetically anisotropic SrRuO3 films,"Epitaxially strained SrRuO3 films have been a model system for understanding
+the magnetic anisotropy in metallic oxides. In this paper, we investigate the
+anisotropy of the Ru 4d and O 2p electronic structure and magnetic properties
+using high-quality epitaxially strained (compressive and tensile) SrRuO3 films
+grown by machine-learning-assisted molecular beam epitaxy. The element-specific
+magnetic properties and the hybridization between the Ru 4d and O 2p orbitals
+were characterized by Ru M2,3-edge and O K-edge soft X-ray absorption
+spectroscopy and X-ray magnetic circular dichroism measurements. The
+magnetization curves for the Ru 4d and O 2p magnetic moments are identical,
+irrespective of the strain type, indicating the strong magnetic coupling
+between the Ru and O ions. The electronic structure and the orbital magnetic
+moment relative to the spin magnetic moment are isotropic despite the
+perpendicular and in-plane magnetic anisotropy in the compressive-strained and
+tensile-strained SrRuO3 films; i.e., the orbital magnetic moments have a
+negligibly small contribution to the magnetic anisotropy. This result
+contradicts Bruno model, where magnetic anisotropy arises from the difference
+in the orbital magnetic moment between the perpendicular and in-plane
+directions. Contributions of strain-induced electric quadrupole moments to the
+magnetic anisotropy are discussed, too.",2205.06563v1
+2022-08-01,Observation of gigantic spin conversion anisotropy in bismuth,"Whilst the g-factor can be anisotropic due to the spin-orbit interaction
+(SOI), its existence in solids cannot be simply asserted from a band structure,
+which hinders progress on studies from such the viewpoints. The g-factor in
+bismuth (Bi) is largely anisotropic; especially for holes at T-point, the
+g-factor perpendicular to the trigonal axis is negligibly small (< 0.112),
+whereas the g-factor along the trigonal axis is very large (62.7). We clarified
+in this work that the large g- factor anisotropy gives rise to the gigantic
+spin conversion anisotropy in Bi from experimental and theoretical approaches.
+Spin-torque ferromagnetic resonance was applied to estimate the spin conversion
+efficiency in rhombohedral (110) Bi to be 17%, which is unlike the negligibly
+small efficiency in Bi(111). Harmonic Hall measurements supports the large spin
+conversion efficiency in Bi(110). This is the first observation of gigantic
+spin conversion anisotropy as the clear manifestation of the g-factor
+anisotropy. Beyond the emblematic case of Bi, our study unveiled the
+significance of the g-factor anisotropy in condensed-matter physics and can
+pave a pathway toward establishing novel spin physics under g-factor control.",2208.00589v3
+2022-08-31,Large Magnetic Anisotropy and Magnetostriction in Thin Films of CoV$_2$O$_4$,"Spinel Cobalt Vanadate CoV$_2$O$_4$ has been grown on (001) SrTiO$_3$
+substrates. Using torque magnetometry experiments, we find that the previously
+observed temperature induced anisotropy change, where the easy axis changes
+from the out of plane [001] direction to a biaxial anisotropy with planar <100>
+easy axes, occurs in a gradual second-order structural phase transition. This
+work characterizes this transition and the magnetic anisotropies in the (001),
+(100), and (-110) rotation planes, and explores their field dependence up to
+30~T. Below 80~K, hysteretic features appear around the hard axes, i.e., the
+out-of-plane direction in (-110) and (010) rotations and the planar <110>
+directions in (001) rotations. This is due to a Zeeman Energy that originates
+from the lag of the magnetization with respect to the applied magnetic field as
+the sample is rotated. The appearance of the hysteresis, which persist up to
+very high fields, shows that the anisotropy at low temperature is rather
+strong. Additionally, field dependent distortions to the symmetry of the torque
+response in increasing applied fields shows that magnetostriction plays a large
+role in determining the direction and magnitude of the anisotropy.",2209.00047v2
+2022-11-16,Continuous Electrical Manipulation of Magnetic Anisotropy and Spin Flopping in van der Waals Ferromagnetic Devices,"Controlling the magnetic anisotropy of ferromagnetic materials plays a key
+role in magnetic switching devices and spintronic applications. Examples of
+spin-orbit torque devices with different magnetic anisotropy geometries
+(in-plane or out-of-plane directions) have been demonstrated with novel
+magnetization switching mechanisms for extended device functionalities.
+Normally, the intrinsic magnetic anisotropy in ferromagnetic materials is
+unchanged within a fixed direction, and thus, it is difficult to realize
+multifunctionality devices. Therefore, continuous modulation of magnetic
+anisotropy in ferromagnetic materials is highly desired but remains
+challenging. Here, we demonstrate a gate-tunable magnetic anisotropy transition
+from out-of-plane to canted and finally to in-plane in layered Fe$_5$GeTe$_2$
+by combining the measurements of the angle-dependent anomalous Hall effect and
+magneto-optical Kerr effect with quantitative Stoner-Wohlfarth analysis. The
+magnetic easy axis continuously rotates in a spin-flop pathway by gating or
+temperature modulation. Such observations offer a new avenue for exploring
+magnetization switching mechanisms and realizing new spintronic
+functionalities.",2211.08909v1
+2023-01-22,Easy-plane spin Hall oscillator,"Spin Hall oscillators (SHOs) based on bilayers of a ferromagnet (FM) and a
+non-magnetic heavy metal (HM) are electrically tunable nanoscale microwave
+signal generators. Achieving high output power in SHOs requires driving
+large-amplitude magnetization dynamics by a direct spin Hall current. The
+maximum possible amplitude of such oscillations with the precession cone angle
+nearing $90^\circ$ is predicted for FM layers with easy-plane magnetic
+anisotropy and spin Hall current polarization perpendicular to the easy plane.
+While many FMs exhibit natural easy-plane anisotropy in the FM film plane, the
+spin Hall current in a HM|FM bilayer is polarized in this plane and thus cannot
+drive large-amplitude magneto-dynamics. Here we present a new type of SHO
+engineered to have the easy-plane anisotropy oriented normal to the film plane,
+enabling large-amplitude easy-plane dynamics driven by spin Hall current. Our
+experiments and micromagnetic simulations demonstrate that the desired
+easy-plane anisotropy can be achieved by tuning the magnetic shape anisotropy
+and perpendicular magnetic anisotropy in a nanowire SHO, leading to a
+significant enhancement of the generated microwave power. The easy-plane SHO
+experimentally demonstrated here is an ideal candidate for realization of a
+spintronic spiking neuron. Our results provide a new approach to design of
+high-power SHOs for wireless communications, neuromorphic computing, and
+microwave assisted magnetic recording.",2301.09228v1
+2023-04-26,Exploring the origins of perpendicular magnetic anisotropy in amorphous Tb-Co via changes in medium-range ordering,"Amorphous thin films of Tb$_{17}$Co$_{83}$ (a-Tb-Co) grown by magnetron
+co-sputtering exhibit changes in magnetic anisotropy with varying growth and
+annealing temperatures. The magnetic anisotropy constant increases with
+increasing growth temperature, which is reduced or vanishes upon annealing at
+temperatures above the growth temperature. The proposed explanation for this
+growth-induced anisotropy in high orbital moment Tb-based transition metal
+alloys such as a-Tb-Co is an amorphous phase texturing with preferential
+in-plane and out-of-plane local bonding configurations for the rare-earth and
+transition metal atoms. Scanning nanodiffraction performed in a transmission
+electron microscope (TEM) is applied to a-Tb$_{17}$Co$_{83}$ films deposited
+over a range of temperatures to measure relative changes in medium-range
+ordering (MRO). These measurements reveal an increase in MRO with higher growth
+temperatures and a decrease in MRO with higher annealing temperatures. The
+trend in MRO indicates a relationship between the magnetic anisotropy and local
+atomic ordering. Tilting select films between 0$^{\circ}$ and 40$^{\circ}$ in
+the TEM measures variations in the local atomic structure a function of
+orientation within the films. The findings support claims that preferential
+ordering along the growth direction results from temperature-mediated adatom
+configurations during deposition, and that oriented MRO correlates with the
+larger anisotropy constants.",2304.13208v3
+2023-04-26,Bond-dependent anisotropy and magnon decay in cobalt-based Kitaev triangular antiferromagnet,"The Kitaev model, a honeycomb network of spins with bond-dependent
+anisotropic interactions, is a rare example of having a quantum spin liquid
+ground state. Although most Kitaev model candidate materials eventually order
+magnetically due to inevitable non-Kitaev terms, their bond-dependent
+anisotropy manifests in unusual spin dynamics. It has recently been suggested
+that bond-dependent anisotropy can stabilise novel magnetic phases and exotic
+spin dynamics on the geometrically frustrated triangular lattice. However, few
+materials have been identified with simultaneous geometric frustration and
+bond-dependent anisotropy. Here, we report a frustrated triangular lattice with
+bond-dependent anisotropy in the cobalt-based triangular van der Waals
+antiferromagnet CoI2. Its momentum and energy-resolved spin dynamics exhibit
+substantial magnon breakdown and complex level repulsion, as measured by
+inelastic neutron scattering. A thorough examination of excitations in both the
+paramagnetic and magnetically ordered states reveals that the bond-dependent
+anisotropy is the origin of the spiral order and the magnon breakdown found in
+CoI2. Our result paves the way toward a new research direction for the Kitaev
+model with geometrical frustration.",2304.13236v3
+2023-05-22,On the isotropy of SnIa absolute magnitudes in the Pantheon+ and SH0ES samples,"We use the hemisphere comparison method to test the isotropy of the SnIa
+absolute magnitudes of the Pantheon+ and SH0ES samples in various
+redshift/distance bins. We compare the identified levels of anisotropy in each
+bin with Monte-Carlo simulations of corresponding isotropised data to estimate
+the frequency of such levels of anisotropy in the context of an underlying
+isotropic cosmological. We find that the identified levels of anisotropy in all
+bins are consistent with the Monte-Carlo isotropic simulated samples. However,
+in the real samples for both the Pantheon+ and the SH0ES cases we find sharp
+changes of the level of anisotropy occuring at distances less than $40Mpc$. For
+the Pantheon+ sample we find that the redshift bin $[0.005,0.01]$ is
+significantly more anisotropic than the other 5 redshift bins considered. For
+the SH0ES sample we find a sharp drop of the anisotropy level at distances
+larger than about $30Mpc$. These anisotropy transitions are relatively rare in
+the Monte-Carlo isotropic simulated data and occur in $2\%$ of the SH0ES
+simulated data and at about $7\%$ of the Pantheon+ isotropic simulated samples.
+This effect is consistent with the experience of an off center observer in a
+$30Mpc$ bubble of distinct physics or systematics.",2305.12819v1
+2023-10-30,Strong in-plane magnetic anisotropy (Co0.15Fe0.85)5GeTe2/graphene van der Waals heterostructure spin-valve at room temperature,"Van der Waals (vdW) magnets are promising owing to their tunable magnetic
+properties with doping or alloy composition, where the strength of magnetic
+interactions, their symmetry, and magnetic anisotropy can be tuned according to
+the desired application. However, most of the vdW magnet based spintronic
+devices are so far limited to cryogenic temperatures with magnetic anisotropies
+favouring out-of-plane or canted orientation of the magnetization. Here, we
+report room-temperature lateral spin-valve devices with strong in-plane
+magnetic anisotropy of the vdW ferromagnet (Co0.15Fe0.85)5GeTe2 (CFGT) in
+heterostructures with graphene. Magnetization measurements reveal above
+room-temperature ferromagnetism in CFGT with a strong in-plane magnetic
+anisotropy. Density functional theory calculations show that the magnitude of
+the anisotropy depends on the Co concentration and is caused by the
+substitution of Co in the outermost Fe layer. Heterostructures consisting of
+CFGT nanolayers and graphene were used to experimentally realize basic building
+blocks for spin valve devices such as efficient spin injection and detection.
+The spin transport and Hanle spin precession measurements prove a strong
+in-plane and negative spin polarization at the interface with graphene, which
+is supported by the calculated spin-polarized density of states of CFGT. The
+in-plane magnetization of CFGT at room temperature proves its usefulness in
+graphene lateral spin-valve devices, thus opening further opportunities for
+spintronic technologies.",2310.19618v1
+2023-11-09,Signature of surface anisotropy in the spin-flip neutron scattering cross section of spherical nanoparticles: atomistic simulations and analytical theory,"We investigate the signature of magnetic surface anisotropy in nanoparticles
+in their spin-flip neutron scattering cross section. Taking into account the
+isotropic exchange interaction, an external magnetic field, a uniaxial or cubic
+magnetic anisotropy for the particle's core, and several models for the surface
+anisotropy (N\'eel, conventional, random), we compute the spin-flip small-angle
+neutron scattering (SANS) cross section from the equilibrium spin structures
+obtained using the Landau-Lifshitz equation. The sign of the surface anisotropy
+constant, which is related to the appearance of tangential- or radial-like spin
+textures, can be distinguished from the momentum-transfer dependence of the
+spin-flip signal. The data cannot be described by the well-known and often-used
+analytical expressions for uniformly magnetized spherical or core-shell
+particles, in particular at remanence or at the coercive field. Based on a
+second-order polynomial expansion for the magnetization vector field, we
+develop a novel minimal model for the azimuthally-averaged magnetic SANS cross
+section. The theoretical expression considers a general magnetization
+inhomogeneity and is not restricted to the presence of surface anisotropy. It
+is shown that the model describes very well our simulation data as well as more
+complex spin patterns such as vortex-like structures. Only seven expansion
+coefficients and some basis functions are sufficient to describe the scattering
+behavior of a very large number of atomic spins.",2311.05706v1
+2023-11-30,Effects of anisotropic pressure on interacting quark star structure,"Perturbative Quantum Chromodynamics (pQCD) corrections and color
+superconductivity predict that strongly interacting matter can reveal new
+physical phenomena under extreme conditions. Taking into account these
+interaction effects, we investigate the role of anisotropic pressure in quark
+stars composed of interacting quark matter. Adopting two physically
+well-motivated anisotropy profiles, we numerically solve the stellar structure
+equations in order to explore the consequences of anisotropic pressure on
+various macroscopic properties such as radius, gravitational mass, surface
+redshift, moment of inertia, tidal Love number and oscillation spectrum.
+Remarkably, for both anisotropy models, negative anisotropies increase the
+radial stability of interacting quark stars, while the opposite occurs for
+positive anisotropies. However, for the Bowers-Liang profile, the central
+density corresponding to the maximum-mass point does not coincide with the
+central density where the squared oscillation frequency vanishes, indicating
+that the existence of stable anisotropic interacting quark stars is possible
+beyond the maximum mass for negative anisotropies. Additionally, we compare our
+theoretical predictions with several observational mass-radius measurements and
+tidal deformability constraints, which suggest that both strong interaction
+effects and anisotropy effects play a crucial role in describing compact stars
+observed in the Universe.",2311.18770v2
+2024-02-03,Magnetosheath ion field-aligned anisotropy and implications for ion leakage to the foreshock,"The ion foreshock is highly dynamic, disturbing the bow shock and the
+magnetosphere-ionosphere system. To forecast foreshock-driven space weather
+effects, it is necessary to model foreshock ions as a function of upstream
+shock parameters. Case studies in the accompanying paper show that
+magnetosheath ions sometimes exhibit strong field-aligned anisotropy towards
+the upstream direction, which may be responsible for enhancing magnetosheath
+leakage and therefore foreshock ion density. To understand the conditions
+leading to such an anisotropy and the potential for enhanced leakage, we
+perform case studies and a statistical study of magnetosheath and foreshock
+region data surrounding ~500 THEMIS bow shock crossings. We quantify the
+anisotropy using the heat flux along the field-aligned direction. We show that
+the strong field-aligned heat flux persists across the entire magnetosheath
+from the magnetopause to the bow shock. Ion distribution functions reveal that
+the strong heat flux is caused by a secondary thermal population. We find that
+stronger anisotropy events exhibit heat flux preferentially towards the
+upstream direction near the bow shock and occur under larger IMF strength and
+larger solar wind dynamic pressure and/or energy flux. Additionally, we show
+that near the bow shock, magnetosheath leakage is a significant contributor to
+foreshock ions, and through enhancing the leakage the magnetosheath ion
+anisotropy can modulate the foreshock ion velocity and density. Our results
+imply that likely due to field line draping and compression against the
+magnetopause that leads to a directional mirror force, modeling the foreshock
+ions necessitates a more global accounting of downstream conditions.",2402.01978v1
+2024-03-16,Nonequilibrium tricritical behaviour in anisotropic XY ferromagnet driven by elliptically polarised propagating magnetic field wave,"Three dimensional anisotropic XY ferromagnet driven by elliptically polarized
+propagating magnetic field wave has been extensively investigated by Monte
+Carlo simulation with Metropolis single spin flip algorithm. Both the effects
+of the bilinear exchange type and the single site anisotropies are thoroughly
+investigated. The time average magnetisation (over the complete cycle of the
+elliptically polarized propagating magnetic field wave) components play the
+role of dynamic order parameter. For fixed set of values of the strength of
+anisotropy and the field amplitudes, the system has been found to get
+dynamically ordered at a pseudocritical temperature. The pseudocritical
+temperature of such dynamic nonequilibrium phase transition has been found to
+depend on both the strength of anisotropy and the amplitudes of the
+elliptically polarized propagating magnetic field wave. A comprehensive phase
+diagram is represented here in the form of image plot of the pseudocritical
+temperature in the plane formed by the strength of anisotropy and field
+amplitudes. Interestingly, this nonequilibrium phase transition has been found
+discontinuous (first order) for higher values of the field amplitude and lower
+values of the anisotropy. On the other hand, the continuous (second order)
+transition has been noticed for lower values of the field amplitude and higher
+values of the anisotropy.",2403.10975v2
+1995-01-24,A Calculation of Cosmic Variance in Cosmic Microwave Background Anisotropy,"We present a theoretical calculation of the variance $\Delta C_l$ of the CMB
+anisotropy power spectrum $\langle C_l\rangle$ caused by gravitational waves
+based on quantum field theory in an inflationary cosmology.",9501088v2
+1996-06-11,Microwave Anisotropies from Random Sources,"I report on recent developments in the theory of cosmic background radiation
+perturbations. I describe ways of modeling alternatives to the canonical
+Gaussian theories within the standard framework of cosmological perturbation
+theory. Some comments are made on using these techniques to resolve the
+uncertainties in theories of structure formation with topological defects. (To
+appear in the proceedings of the XXXIth Moriond meeting, ``Microwave Background
+Anisotropies'')",9606068v1
+1996-11-27,Theoretical implications of microwave background radiation anisotropy experiments,"Observational results from several experiments such as COBE, SP, Saskatoon,
+PYTHON, ARGO, MAX, MSAM, Tenerife and CAT are considered and a comparison is
+made with predictions from several models. Conclusions are reached about the
+viability of current structure formation models.",9611228v1
+1997-05-13,The Cosmic Microwave Background Spectrum,"This paper given at the Strasbourg NATO school on the CMB and cosmology
+reports the contents of four hours of lectures on the CMB spectrum, potential
+distortions, and implications. It was followed by 6 hours of lectures on CMB
+anisotropy. This paper reviews the observations and theoretical implications
+for the CMB frequency spectrum - both for the monopole (essentially total
+power) and the dipole and higher order anisotropies including the
+Sunyaev-Zeldovich effect.",9705101v2
+1997-05-21,On the Computation of CMBR Anisotropies from Simulations of Topological Defects,"Techniques for computing the CMBR anisotropy from simulations of topological
+defects are discussed with an eye to getting as much information from a
+simulation as possible. Here we consider the practical details of which sums
+and multiplications to do and how many terms there are.",9705177v1
+1997-07-09,Polarization-Temperature Correlation from a Primordial Magnetic Field,"We propose a new method for constraining a primordial homogeneous magnetic
+field with the cosmic microwave background. Such a field will induce an
+observable parity odd cross correlation between the polarization anisotropy and
+the temperature anisotropy by Faraday rotation. We analyze the necessary
+experimental features to match, and improve, current constraints of such a
+field by measuring this correlation.",9707115v1
+1998-04-14,CMB anisotropy measurements using stratospheric balloons,"We review the topic of Cosmic Microwave Background Anisotropy measurements
+carried out by means of balloon-borne telescopes. After a short description of
+the experimental methodology, we outline the peculiar problems of these
+experiments, and we describe the main results obtained and the perspects for
+future developments.",9804138v1
+1998-10-30,Polarization of the CMB Anisotropy,"I review why we expect the CMB anisotropy to be polarized, what we can learn
+from studying polarization and the level of the experimental challenge it
+presents. A discussion of current and future polarization sensitive experiments
+will focus on the expected sensitivity of PLANCK.",9810506v1
+1999-11-29,Cosmic Microwave Background Anisotropies: Inflation versus Topological Defects,"I present a briefly summary of the current status of inflationary models
+versus topological defects scenarios, as the mechanisms which could have
+induced the initial density perturbations, which left an imprint on the cosmic
+microwave backgound radiation anisotropies.",9911497v1
+2000-02-15,Sachs-Wolfe effect in space-times with torsion,"Cartan torsion contribution to Sachs-Wolfe effect in the inflationary phase
+of the Universe is discussed.From the COBE data of the microwave anisotropy is
+possible to compute the spin-density in the Universe as $10^{16}$ mks units.The
+spin-density fluctuations at the hadron era is shown to coincide with the
+anisotropy temperature fluctuations.",0002301v1
+2000-09-18,Complex Visibilities of Cosmic Microwave Background Anisotropies,"We study the complex visibilities of the cosmic microwave background
+anisotropies that are observables in interferometric observations of the cosmic
+microwave background, using the multipole expansion methods commonly adopted in
+analyzing single-dish experiments. This allows us to recover the properties of
+the visibilities that is obscured in the flat-sky approximation. Discussions of
+the window function, multipole resolution, instrumental noise, pixelization,
+and polarization are given.",0009277v1
+2000-10-23,Precision of inflationary predictions and recent CMB anisotropy data,"Inflationary predictions of the cosmic microwave background anisotropy are
+often based on the slow-roll approximation. We study the precision of these
+predictions and compare them with the recent data from BOOMERanG and MAXIMA-1.",0010453v1
+2000-11-23,Issues and methods for CMB anisotropy data reduction,"Major issues and existing methods for the reduction of CMB anisotropy data
+are reviewed. An emphasis is put on the proper modelling of the data. It is
+suggested that the robustness of methods could be improved by taking into
+account the uncertainty of the model for finding optimal solutions.",0011444v1
+2001-05-16,Window Function for Non-Circular Beam CMB Anisotropy Experiment,"We develop computationally rapid methods to compute the window function for a
+cosmic microwave background anisotropy experiment with a non-circular beam
+which scans over large angles on the sky. To concretely illustrate these
+methods we compute the window function for the Python V experiment which scans
+over large angles on the sky with an elliptical Gaussian beam.",0105270v1
+2001-06-07,Anisotropy analysis of EAS data in the knee region,"Based on MAKET-ANI EAS data the distributions of equatorial coordinates of
+EAS core directions are obtained in the knee region. Anisotropy of primary
+cosmic rays is displayed only by declination equatorial coordinates (20+/-3
+degrees) at primary energies more than 5-10 PeV. The fraction of anisotropic
+component turns out ~10% in the knee region.",0106124v1
+2001-09-17,Physics of Cosmic Microwave Background anisotropies and primordial fluctuations,"The physics of the origin and evolution of CMB anisotropies is described. I
+explain the idea and status of cosmic parameter estimation and follow it up
+with critical comments on its dependence on model assumptions and initial
+conditions.",0109274v1
+2003-02-13,Probing the star formation epoch with Wilkinson Microwave Anisotropy Probe (WMAP) data and high-redshift QSOs,"Using the values of the cosmological parameters obtained from Wilkinson
+Microwave Anisotropy Probe (WMAP) and the cosmological chemical clock observed
+by high-redshift quasars, it is shown that star formation should have started
+by the redshift $z_F > 9.5$, and that $z_F$ is sensitive only to $\omegamz h^2$
+in flat $\Lambda$CDM cosmology.",0302263v1
+2004-01-30,Anisotropies in Ultrahigh Energy Cosmic Rays,"The present status of anisotropy studies for the highest energy cosmic rays
+is presented including the first full sky survey. Directions and prospects for
+the future are also discussed in light of new statistical methods and the last
+quantities of data expected in the near future from the Pierre Auger
+Observatory.",0401632v1
+2004-12-01,Initial power spectrum shape,"Mainly used to set constraints on cosmological parameters, CMB anisotropies
+can give information on primordial universe. Unfortunately, initial conditions
+and late time cosmology are degenerated. I focus on the effect of the shape of
+the initial power spectrum of fluctuations on the cosmological parameter
+estimation from CMB temperature anisotropies. Strong constraints obtained using
+a priori knowledge of the initial spectrum disappear when the latter is let
+free.",0412022v1
+2006-07-05,A No-Truncation Approach to Cosmic Microwave Background Anisotropies,"We offer a method of calculating the source term in the line-of-sight
+integral for cosmic microwave background anisotropies without using a truncated
+partial-wave expansion in the Boltzmann hierarchy.",0607076v2
+2007-02-11,Ellipsoidal Universe Induces Large Scale CMB Polarization,"We calculate the large scale polarization of the cosmic microwave background
+induced by the anisotropy of the spatial geometry of our universe. Assuming an
+eccentricity at decoupling of about $0.64 10^{-2}$, we find $\Delta T_{pol}/
+T_0 \simeq 0.53 10^{-6}$ quite close to the average level of polarization
+detected by the Wilkinson Microwave Anisotropy Probe.",0702293v2
+1997-10-28,Field-induced quasi-particle coherence effects in certain small magnets,"Small ferromagnets and anti-ferromagnets with an easy-plane anisotropy have a
+ground to first excited state (tunnel) splitting which is quasi-periodic in the
+magnitude of a field applied perpendicular to a principal anisotropy axis. The
+associated oscillations in thermodynamic quantities might be used to prove the
+existence of a coherent ground state even when the tunnel splitting itself
+cannot be directly detected.",9710302v1
+1998-05-15,Gauge Equivalence between Two-Dimensional Heisenberg Ferromagnets with Single-Site Anisotropy and Zakharov Equations,"Gauge equivalence between the two-dimensional continuous classical Heisenberg
+ferromagnets(CCHF) of spin 1/2 - the M-I equation with single site anisotropy
+and the Zakharov equation(ZE) is established for the easy axis case. The
+anisotropic CCHF is shown to be gauge equivalent to the isotropic CCHF.",9805188v1
+1999-04-18,Orientational phase transitions in anisotropic rare-earth magnets at low temperatures,"Orientational phase transitions are investigated within the Heisenberg model
+with single-site anisotropy. The temperature dependence of the cone angle is
+calculated within the spin-wave theory. The role of the quantum
+renormalizations of anisotropy constants is discussed. A comparison with the
+experimental data on the cone-plane orientational transition in holmium is
+performed.",9904251v1
+2001-01-31,Spin-orbit induced anisotropy in the magnetoconductance of two-dimensional metals,"It is shown that the spin-orbit coupling due to structure inversion asymmetry
+leads to a characteristic anisotropy in the magnetoconductance of
+two-dimensional metals. Relevance for recent experiments is discussed.",0101473v1
+2001-04-13,Dipolar induced anisotropy in the random-field Ising model,"The crystalline ferromagnet with dipole-dipole interactions is studied within
+the framework of the three-dimensional random-field Ising model. The field
+distribution function and the analytic expression for temperature dependent
+free energy are found. The dipolar induced magnetic anisotropy energy of bulk
+cubic ferromagnetic materials is calculated.",0104246v1
+2001-06-18,A microscopic model for exchange bias,"The domain state model for exchange bias has been further investigated by
+considering vector spins for the antiferromagnet instead of Ising spins used in
+the earlier studies. The qualitative results are similar to those with infinite
+anisotropy for the antiferromagnet. However, under certain conditions softer
+spins can lead to an even stronger bias field. The study shows a nontrivial
+dependence of the exchange bias on the antiferromagnetic anisotropy.",0106333v1
+2001-08-05,Low Energy Behaviour of XXZ Antiferromagnetic Spin Chain,"Zero temperature phase diagram of XXZ spin chain in external magnetic field
+is investigated at low energies using path integral approach.It has been shown
+by spin wave analysis and then by nonlinear sigma model transformation that
+below some critical field the system undergoes quantum Kosterlitz-Thouless
+phase transition.Above that critical field for low anisotropies the system is
+saturated while at strong anisotropy the system has Ising antiferromagnetic
+order.",0108086v1
+2002-03-13,Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane Magnetoresistance in High-Mobility (100) Si Inversion Layers,"Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane
+Magnetoresistance in High-Mobility (100) Si Inversion Layers",0203276v1
+2002-07-05,Anisotropy of the upper critical field in superconductors with anisotropic gaps. Anisotropy parameters of MgB2,"The upper critical field Hc2 is evaluated for weakly-coupled two-band
+superconductors. By modeling the actual bands and the gap distribution of MgB2
+by two Fermi surface spheroids with average parameters of the real material, we
+show that H_{c2,ab}/H_{c2,c} increases with decreasing temperature in agreement
+with available data.",0207146v1
+2004-02-09,Evidence of large anisotropy in the magnetization of Na0.35CoO2.1.3H2O quasi-single-crystal superconductors,"Quasi-single crystals (up to 2x2x1 mm3) of Na0.35CoO2.1.3H2O-superconductor
+have been grown. Magnetization M(H, T) and M(T, H) curves with magnetic field
+approximately parallel and perpendicular to c-axis indicates on large
+anisotropy, comparable with Bi-based high-temperature superconducting (HTS)
+phases.",0402235v1
+2005-11-21,Magnetization reversal in the anisotropy-dominated regime using time-dependent magnetic fields,"We study magnetization reversal using various r.f. magnetic pulses. We show
+numerically that switching is possible with simple sinusoidal pulses; however
+the optimum approach is to use a frequency-swept (chirped) r.f. magnetic pulse,
+the shape of which can be derived analytically. Switching times of the order of
+nanoseconds can be achieved with relatively small r.f. fields, independent of
+the anisotropy's strength.",0511497v1
+2006-06-14,Anisotropy of heat capacity in Pauli limited unconventional superconductors,"Diamagnetically coupled magnetic field can be used as a probe of nodal
+positions in unconventional superconductors. The heat capacity depends on the
+angle $\phi_0$ between the magnetic field and the nodal directions. We show
+that the anisotropy $C(\phi_0)$ persists even in systems with strong
+paramagnetic coupling to the electrons's spins.",0606390v1
+2007-03-11,Time-dependent fields and anisotropy dominated magnetic media,"We use a single dipole approximation to analyze the behavior of
+anisotropy-dominated magnetic nanoparticles subjected to an external r.f.
+field. We identify the steady state oscillations and analyze their stability.
+We also analyze the case when the external r.f. field has a time-dependent
+frequency which insures the most effective switching of the magnetization.",0703272v1
+1994-05-25,Density Perturbations of Quantum Mechanical Origin and Anisotropy of the Microwave Background,"If the large-angular-scale anisotropy in the cosmic microwave background
+radiation is caused by the long-wavelength cosmological perturbations of
+quantum mechanical origin, they are, most likely, gravitational waves, rather
+than density perturbations or rotational perturbations.",9405059v1
+1998-11-03,A note on light velocity anisotropy,"It is proved that in experiments on or near the Earth, no anisotropy in the
+one-way velocity of light may be detected. The very accurate experiments which
+have been performed to detect such an effect are to be considered significant
+tests of both special relativity and the equivalence principle",9811008v1
+2003-06-23,Modern Michelson-Morley experiments and gravitationally-induced anisotropy of c,"The recent, precise Michelson-Morley experiment performed by Muller et al.
+suggests a tiny anisotropy of the speed of light. I propose a quantitative
+explanation of the observed effect based on the interpretation of gravity as a
+density fluctuation of the Higgs condensate.",0306105v1
+2005-01-11,"Quasi-spherical gravitational collapse and the role of initial data, anisotropy and inhomogeneity","In this paper, the role of anisotropy and inhomogeneity has been studied in
+quasi-spherical gravitational collapse. Also the role of initial data has been
+investigated in characterizing the final state of collapse. Finally, a linear
+transformation on the initial data set has been presented and its impact has
+been discussed.",0501035v1
+1999-12-01,Seeds of Large Scale Anisotropy in Pre-Big-Bang Cosmology,"Within a string cosmology context, the large scale temperature anisotropies
+may arise from the contribution of seeds to the metric fluctuations. We study
+the cases of electromagnetic and axion seeds. We find that massless or very
+light axions can lead to a flat or slightly tilted blue spectrum, that fits
+current data.",9912207v1
+2003-11-25,Cosmological constraints from Microwave Background Anisotropy and Polarization,"The recent high-quality measurements of the Cosmic Microwave Background
+anisotropies have presented cosmologists with the possibility of studying the
+large scale properties of our universe with unprecedented precision. Here I
+review the current status of observations and constraints on theoretical
+models.",0311319v1
+2004-01-22,Noncommutative inflation and the large-scale damping in the CMB anisotropy,"We show that a certain class of short-distance cutoff can give rise to large
+suppression on the CMB anisotropies at large angular scales.",0401153v2
+2005-09-25,Hamiltonian formalism of the Landau-Lifschitz equation for a spin chain with full anisotropy,"The Hamiltonian formalism of the Landau-Lifschitz equation for a spin chain
+with full anisotropy is formulated completely, which constructs a stable base
+for further investigations.",0509042v1
+2004-04-08,"Event anisotropy of identified $π^{0}$, photon and electron compared to charged $π$, $K$, $p$ and deuteron in $\sqrt{s_{NN}}$ = 200 GeV Au+Au at PHENIX","We report the recent results of event anisotropy analysis focused on $v_2$ in
+$\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions at PHENIX.",0404014v1
+2001-02-14,Effects of anisotropy on thermal entanglement,"We study the thermal entanglement in the two-qubit anisotropic XXZ model and
+the Heisenberg model with Dzyaloshinski-Moriya (DM) interactions. The DM
+interaction is another kind of anisotropic antisymmetric exchange interaction.
+The effects of these two kinds of anisotropies on the thermal entanglement are
+studied in detail for both the antiferromagnetic and ferromagnetic cases.",0102072v1
+2007-05-20,Anisotropy and asymmetry in fully developed turbulence,"Using experimental longitudinal and transverse velocities data for very high
+Reynolds number turbulence, we study both anisotropy and asymmetry of
+turbulence. These both seem to be related to small scale turbulent structures,
+and to intermittency. We may assume that the large scale velocity shear gives
+an impact into the small scale turbulence, resulting in non-locality, and
+related anomalous events.",0705.2890v1
+2007-10-08,Lensing and CMB Anisotropies by Cosmic Strings at a Junction,"The metric around straight arbitrarily-oriented cosmic strings forming a
+stationary junction is obtained at the linearized level. It is shown that the
+geometry is flat. The sum rules for lensing by this configuration and the
+anisotropies of the CMB are obtained.",0710.1636v1
+2008-01-10,Order parameter configurations in the Lifshitz-type incommensurate ferroelectric thin films,"The Dzialoshinskii model of periodic and helicoidal structures has been
+analyzed without neglecting of the amplitude function oscillations. The
+amplitude function oscillations are shown to be important for understanding of
+the nature of the phase function. Analytic consideration is carried out in the
+limit of small anisotropy (neglecting the cosine term in the Hamiltonian).
+Surprisingly, the phase jumps survive even in the limit of the vanishing
+anisotropy.",0801.1583v1
+2008-05-20,A Search for Cosmic Microwave Background Anisotropies on Arcminute Scales with Bolocam,"We have surveyed two science fields totaling one square degree with Bolocam
+at 2.1 mm to search for secondary CMB anisotropies caused by the Sunyaev-
+Zel'dovich effect (SZE). The fields are in the Lynx and Subaru/XMM SDS1 fields.
+Our survey is sensitive to angular scales with an effective angular multipole
+of l_eff = 5700 with FWHM_l = 2800 and has an angular resolution of 60
+arcseconds FWHM. Our data provide no evidence for anisotropy. We are able to
+constrain the level of total astronomical anisotropy, modeled as a flat
+bandpower in C_l, with frequentist 68%, 90%, and 95% CL upper limits of 590,
+760, and 830 uKCMB^2. We statistically subtract the known contribution from
+primary CMB anisotropy, including cosmic variance, to obtain constraints on the
+SZE anisotropy contribution. Now including flux calibration uncertainty, our
+frequentist 68%, 90% and 95% CL upper limits on a flat bandpower in C_l are
+690, 960, and 1000 uKCMB^2. When we instead employ the analytic spectrum
+suggested by Komatsu and Seljak (2002), and account for the non-Gaussianity of
+the SZE anisotropy signal, we obtain upper limits on the average amplitude of
+their spectrum weighted by our transfer function of 790, 1060, and 1080
+uKCMB^2. We obtain a 90% CL upper limit on sigma8, which normalizes the power
+spectrum of density fluctuations, of 1.57. These are the first constraints on
+anisotropy and sigma8 from survey data at these angular scales at frequencies
+near 150 GHz.",0805.3151v2
+2008-05-26,Magnetic anisotropy in ferromagnetic Josephson junctions,"Magnetotransport measurements were done on $\Nb/\Al_2\O_3/\Cu/\Ni/\Nb$
+superconductor-insulator-ferromagnet-superconductor Josephson tunnel junctions.
+Depending on ferromagnetic $\Ni$ interlayer thickness and geometry the standard
+(1d) magnetic field dependence of critical current deviates from the text-book
+model for Josephson junctions. The results are qualitatively explained by a
+short Josephson junction model based on anisotropy and 2d remanent
+magnetization.",0805.3925v2
+2008-07-26,CMB Temperature Anisotropy from Broken Spatial Isotropy due to an Homogeneous Cosmological Magnetic Field,"We derive the cosmic microwave background temperature anisotropy two-point
+correlation function (including off-diagonal correlations) from broken spatial
+isotropy due to an arbitrarily oriented homogeneous cosmological magnetic
+field.",0807.4239v2
+2009-05-23,Influence of a Transport Current on Magnetic Anisotropy in Gyrotropic Ferromagnets,"Current-induced torques are commonly used to manipulate non-collinear
+magnetization configurations. In this article we discuss current-induced
+torques present in a certain class of collinear magnetic systems, relating them
+to current-induced changes in magnetic anisotropy energy. We present a
+quantitative estimate of their characteristics in uniform strained
+ferromagnetic (Ga,Mn)As.",0905.3856v1
+2009-06-27,The mass and anisotropy profiles of galaxy clusters from the projected phase space density: testing the method on simulated data,"We present a new method of constraining the mass and velocity anisotropy
+profiles of galaxy clusters from kinematic data. The method is based on a model
+of the phase space density which allows the anisotropy to vary with radius
+between two asymptotic values. The characteristic scale of transition between
+these asymptotes is fixed and tuned to a typical anisotropy profile resulting
+from cosmological simulations. The model is parametrized by two values of
+anisotropy, at the centre of the cluster and at infinity, and two parameters of
+the NFW density profile, the scale radius and the scale mass. In order to test
+the performance of the method in reconstructing the true cluster parameters we
+analyze mock kinematic data for 20 relaxed galaxy clusters generated from a
+cosmological simulation of the standard LCDM model. We use Bayesian methods of
+inference and the analysis is carried out following the Markov Chain Monte
+Carlo approach. The parameters of the mass profile are reproduced quite well,
+but we note that the mass is typically underestimated by 15 percent, probably
+due to the presence of small velocity substructures. The constraints on the
+anisotropy profile for a single cluster are in general barely conclusive.
+Although the central asymptotic value is determined accurately, the outer one
+is subject to significant systematic errors caused by substructures at large
+clustercentric distance. The anisotropy profile is much better constrained if
+one performs joint analysis of at least a few clusters. In this case it is
+possible to reproduce the radial variation of the anisotropy over two decades
+in radius inside the virial sphere.",0906.5071v1
+2009-08-03,Killing vectors and anisotropy,"We consider an action that can generate fluids with three unequal stresses
+for metrics with a spacelike Killing vector. The parameters in the action are
+directly related to the stress anisotropies. The field equations following from
+the action are applied to an anisotropic cosmological expansion and an
+extension of the Gott-Hiscock cosmic string.",0908.0354v1
+2009-09-01,Effects of anisotropy in geostrophic turbulence,"The Boussinesq model of convection in a flat layer with heating from below is
+considered. We analyze the effects of anisotropy caused by rapid rotation in
+physical and wave spaces and demonstrate the suppression of energy transfer by
+rotation. We also examine the structure of the wave triangle in nonlinear
+interaction. The range of parameters is adapted to the models of convection in
+the geodynamo.",0909.0149v1
+2009-10-26,The Cosmic Neutrino Background Anisotropy - Linear Theory,"The cosmic neutrino background anisotropy is calculated for massive neutrino
+states by solving the full Boltzmann equation. The effect of weak gravitational
+lensing, including the Limber approximation, is also derived for massive
+particles, and subsequently applied to the case of massive neutrinos.",0910.4578v1
+2009-11-02,Dynamical Toroidal Hopfions in a Ferromagnet with Easy-Axis Anisotropy,"Three-dimensional toroidal precession solitons with a nonzero Hopf index,
+which uniformly move along the anisotropy axis in a uniaxial ferromagnet, have
+been found. The structure and existence region of the solitons have been
+numerically determined by solving the Landau-Lifshitz equation.",0911.0451v1
+2010-01-20,Note on Anisotropy of Resistivity in Hidden Ordered State of URu_2Si_2,"On an assumption that the HO is the antiferro-quadrupolar order with
+\Gamma_{5} (Q_{z(x+y)} and Q_{z(x-y)}) symmetry, the anisotropy in temperature
+dependence of resistivity (\rho_{c}\propto T^{2}, and \rho_{ab}\propto T) in
+the HO phase of URu_2Si_2 is explained.",1001.3516v1
+2010-05-06,The importance of anisotropy for relativistic fluids with spherical symmetry,"It is shown that an effective anisotropic spherically symmetric fluid model
+with heat flow can absorb the addition to a perfect fluid of pressure
+anisotropy, heat flow, bulk and shear viscosity, electric field and null fluid.
+In most cases the induction of effective heat flow can be avoided.",1005.1047v1
+2010-08-12,Anisotropy of DC Electric Field Influence on Acoustic Wave Propagation in Piezoelectric Plate,"Anisotropy of dc electric field influence on the different types of acoustic
+waves in piezoelectric plate has been investigated by means of computer
+simulation. Detail calculations have made for bismuth germanium oxide crystals.",1008.2058v1
+2011-04-29,90-Degree Bloch Domain Wall Structure in a Cubic Crystal with a Negative Magnetic Anisotropy,"An influence of strong sample demagnetization field on the structure of plane
+90-degree Bloch domain walls in a cubic (001)-crystal with a negative first
+constant of magnetic anisotropy is considered.",1105.0013v1
+2011-08-05,On discrete symmetries and relic radiation anisotropy,"It is argued that large scale angle correlations of the Cosmic Microwave
+Background Radiation (CMBR) temperature fluctuations measured by Wilkinson
+Microwave Anisotropy Probe (WMAP) mission may have a trace of discrete
+symmetries of quantum gravity",1108.1254v2
+2012-02-17,CMB Tensor Anisotropies in Metric f(R) Gravity,"We present a description of CMB anisotropies generated by tensor
+perturbations in f(R) theories of gravity. The temperature power spectrum in
+the special case of $f(R)=R^n$ is computed using a modified version of CAMB
+package.",1202.3862v1
+2012-09-11,Towards azimuthal anisotropy of direct photons,"Intensive radiation of magnetic bremsstrahlung type (synchrotron radiation)
+resulting from the interaction of escaping quarks with the collective confining
+colour field is discussed as a new possible mechanism of observed direct photon
+anisotropy.",1209.2380v3
+2012-12-25,Hysteresis behavior of the anisotropic quantum Heisenberg model,"The effect of the anisotropy in the exchange interaction on the hysteresis
+loops within the anisotropic quantum Heisenberg model has been investigated
+with the effective field theory for two spin cluster. Particular attention has
+been devoted on the behavior of the hysteresis loop area, coercive field and
+remanent magnetization with the anisotropy in the exchange interaction for both
+ferromagnetic and paramagnetic phases.",1212.5997v1
+2013-02-04,An optimality result about sample path properties of Operator Scaling Gaussian Random Fields,"We study the sample paths properties of Operator scaling Gaussian random
+fields. Such fields are anisotropic generalizations of anisotropic self-similar
+random fields as anisotropic Fractional Brownian Motion. Some characteristic
+properties of the anisotropy are revealed by the regularity of the sample
+paths. The sharpest way of measuring smoothness is related to these
+anisotropies and thus to the geometry of these fields.",1302.0818v1
+2013-02-04,A strong optimality result for anisotropic self--similar textures,"In previous works, we proposed a method to characterize jointly
+self-similarity and anisotropy properties of a large class of self--similar
+Gaussian random fields. We provide here a mathematical analysis of our
+approach, proving that the sharpest way of measuring smoothness is related to
+these anisotropies and thus to the geometry of these fields.",1302.0819v1
+2013-02-12,Anisotropy and superconductivity,"The mean field method is applied for analysis of valence electrons in metals.
+It is shown that at low temperatures electrons have two wave-vector
+distribution patterns. Isotropic distribution refers to the first pattern.
+Anisotropic distribution refers to another pattern, particularly to specific
+wave-vector values occurred nearby the Fermi sphere. It is shown that it is the
+anisotropy that makes the metal obtain its specific superconductor features.",1302.5066v1
+2013-02-22,CMB Anisotropies by Collapsing Textures,"CMB photons passing through a collapsing texture knot receive an energy
+shift, creating characteristic cold and hot spots on the sky. We calculate the
+anisotropy pattern produced by collapsing texture knots of arbitrary shape. The
+texture dynamics are solved numerically on a Minkowski background.",1302.5627v1
+2013-05-29,The problem of small angular scale structure in the cosmic ray anisotropy data,"Recent observations have revealed structure on small angular scales in the
+anisotropy data of cosmic rays at multi TeV energies. Even though the absolute
+amplitudes are very small, these effects are somewhat surprising and a wide
+range of possible causes have been discussed. A possible origin associated with
+heliospheric electric fields is proposed.",1305.6752v1
+2013-06-27,The anisotropy of a three- and a one-form,"We calculate the anisotropic signal associated with the coupling of a
+three-form with an Abelian vector gauge field. In the simplest examples of
+three-form inflation the amplification of the vector fluctuations is
+exponential; this makes it almost certain that a large anisotropy will develop,
+severely constraining the viability of the coupling.",1306.6429v1
+2014-01-08,Light cone anisotropy in 21 cm signal from the epoch of reionization,"Using a suite of detailed numerical simulations we estimate the level of
+anisotropy generated by the time evolution along the light cone of the 21cm
+signal from the epoch of reionization. Our simulations include the physics
+necessary to model the signal during both the late emission regime and the
+early absorption regime, namely X-ray and Lyman-band 3D radiative transfer in
+addition to the usual dynamics and ionizing UV transfer. The signal is analysed
+using correlation functions perpendicular and parallel to the line of sight
+(LOS). We reproduce general findings from previous theoretical studies: the
+overall amplitude of the correlations and the fact that the light cone
+anisotropy is visible only on large scales (100 cMpc). However, the detailed
+behaviour is different. At 3 different epochs, the amplitude of the
+correlations along and perpendicular to the LOS differ from each other,
+indicating anisotropy. These 3 epochs are associated with 3 events of the
+global reionization history: the overlap of ionized bubbles, the onset of mild
+heating by X-rays in regions around the sources, and the onset of efficient
+Lyman-alpha coupling in regions around the sources. A 20x20 deg^2 survey area
+may be necessary to mitigate sample variance when we use the directional
+correlation functions. On a 100 cMpc scale the light cone anisotropy dominates
+over the anisotropy generated by peculiar velocity gradients computed in the
+linear regime. By modelling instrumental noise and limited resolution, we find
+that the anisotropy should be easily detectable by the SKA, assuming perfect
+foreground removal, the limiting factor being a large enough survey size. In
+the case of the LOFAR, it is likely that only first anisotropy episode will
+fall in the observing frequency range and will be detectable only if sample
+variance is much reduced (i.e. a larger than 20x20 deg^2 survey, which is not
+presently planned).",1401.1807v1
+2014-05-21,Anisotropy results from 193 GeV U+U collisions at RHIC,"We report the measurement of azimuthal anisotropy $v_{n}$ for n = 1-5 as a
+function of transverse momentum $p_{T}$ and centrality in U+U collisions at
+$\sqrt{s_{NN}}$ = 193 GeV, recorded with the STAR detector at RHIC. We also
+present results on $v_{2}$ and azimuthal correlator related to charge
+separation across the reaction plane due to local parity violation(LPV) in the
+ultra-central collisions.",1405.5510v1
+2014-07-21,Implications of the primordial anisotropy for a scalar field with non-minimal kinetic coupling,"We consider a scalar field with a kinetic term non-minimally coupled to
+gravity in an anisotropic background. Various potentials for the scalar field
+are considered. By explicit examples, we show that how the anisotropy can
+change the dynamics of the scalar field compared with the isotropic background.",1407.5421v1
+2015-03-24,Nuclear modification and azimuthal anisotropy of D mesons produced in relativistic heavy ion collision,"In this paper we present a phenomenological treatment of charm quark energy
+loss before fragmenting into D mesons and calculate nuclear modification
+factor, '$R_{AA}$' and azimuthal anisotropy, '$v_2$' of D mesons for lead on
+lead collision at LHC energy of $\sqrt{s}$=2.76 A TeV.",1503.06936v1
+2015-06-11,Hysteresis Behavior of Anisotropic Heisenberg Model in Thin Film Geometry,"The effect of the anisotropy in the exchange interaction and film thickness
+on the hysteresis behavior of the anisotropic Heisenberg thin film has been
+investigated with effective field formulation in a two spin cluster using the
+decoupling approximation. The behaviors of the hysteresis loop area, coersive
+field and remanent magnetization with the film thickness and anisotropy in the
+exchange interaction have been obtained.",1506.03641v2
+2015-09-18,27-day Variation of the Three Dimensional Solar Anisotropy of Galactic Cosmic Ray: 1965-2014,"The temporal evaluation of the 27-day variation of the three dimensional (3D)
+galactic cosmic ray (GCR) anisotropy has been studied for 1965-2014. 3D
+anisotropy vector was obtained based on the neutron monitors and Nagoya muon
+telescopes data. We analyze the 27-day variation of the (1) two dimensional
+(2D) GCR anisotropy in the ecliptic plane, and (2) north-south anisotropy
+normal to the ecliptic plane. Studying the time line of the 27-day variation of
+the 2D GCR anisotropy, we confirm that the average amplitude in the minimum
+epoch of solar activity is polarity dependent, as it is expected from the drift
+theory. The amplitude in the negative polarity epochs is less as we had shown
+before. The feeble 11-year variation connected with solar cycle and strong
+22-year pattern connected with solar magnetic cycle is visible in the 27-day
+variation of the 2D anisotropy for 1965-2014. We show that the 27-day variation
+of the GG index (being a measure of the north-south asymmetry) varies in
+accordance to solar cycle with a period of 11-years, being in good agreement
+with the 27-day variation of the At component of the GCR anisotropy calculated
+by the IZMIRAN group. Detailed analysis are presented for the solar minimum
+2007-2008 of solar cycle no.23 and solar maximum 2013-2015 of solar cycle no
+24. In the solar cycle no. 24 GG index, calculated by Nagoya telescopes data,
+is highly anticorrelated with By component of the interplanetary magnetic field
+(IMF) and shows a clear recurrent changes related to the Sun's rotation.",1509.05770v1
+2015-12-04,Primordial gravity wave background anisotropies,"We consider the primordial gravity wave background produced by inflation. We
+compute the small anisotropy produced by the primordial scalar fluctuations.",1512.01531v3
+2016-03-28,Electric-field modulation of exchange stiffness in MgO/CoFeB with perpendicular anisotropy,"We observe magnetic domain structures of MgO/CoFeB with a perpendicular
+magnetic easy axis under an electric field. The domain structure shows a maze
+pattern with electric-field dependent isotropic period. We find that the
+electric-field modulation of the period is explained by considering the
+electric-field modulation of the exchange stiffness constant in addition to the
+known magnetic anisotropy modulation.",1603.08280v1
+2016-09-05,Numerical examination of commutativity between Backus and Gazis et al. averages,"Dalton and Slawinski (2016) show that, in general, the Backus (1962) average
+and the Gazis et al. (1963) average do not commute. Herein, we examine the
+extent of this noncommutativity. We illustrate numerically that the extent of
+noncommutativity is a function of the strength of anisotropy. The averages
+nearly commute in the case of weak anisotropy.",1609.01034v1
+2016-11-28,Numerical Study of Pseudo-gap Anisotropy for a Tight Binding Band,"The Fermi surface anisotropy of a pseudo-gap in the spectral weight, caused
+by superconducting fluctuations or anti-ferromagnetic fluctuations, is
+calculated for a tight binding band. The importance of the Fermi surface saddle
+point, or hot spot, is illustrated. A peak-dip-hump structure due to a finite
+frequency mode, is briefly explored. The connection to high temperature
+superconducting copper-oxides is discussed.",1611.09305v1
+2017-08-01,Effect of radiation-like solid on CMB anisotropies,"We compute the CMB angular power spectrum in the presence of the
+radiation-like solid with the same pressure to energy density ratio as for the
+radiation but with nonzero shear modulus. The effect can be observable not only
+for large-angle anisotropies as shown by Balek and \v{S}kovran [2015] but also
+for very small-angle ones.",1708.00237v1
+2017-11-14,Generalized crystalline evolutions as limits of flows with smooth anisotropies,"We prove existence and uniqueness of weak solutions to anisotropic and
+crystalline mean curvature flows, obtained as limit of the viscosity solutions
+to flows with smooth anisotropies.",1711.04997v1
+2018-07-04,Magnetic properties in the metallic magnets with large anisotropy,"We study low temperature properties in the metallic magnets, considering the
+itinerant electron mediated ferromagnetism. Applying the Monte Carlo
+simulations to the extended double exchange model, we discuss reorientation
+phase transition and anisotropy field for the metallic magnets.",1807.01405v1
+2018-10-30,Q-operators for higher spin eight vertex models with a rational anisotropy parameter,"Q-operators for generalised eight vertex models associated to higher spin
+representations of the Sklyanin algebra are constructed by Baxter's first
+method and Fabricius's method, when the anisotropy parameter is rational.",1810.12969v1
+2019-04-12,Quasilinear approach of the cumulative whistler instability in fast solar winds: Constraints of electron temperature anisotropy,"Context. Solar outflows are a considerable source of free energy which
+accumulates in multiple forms like beaming (or drifting) components and/or
+temperature anisotropies. However, kinetic anisotropies of plasma particles do
+not grow indefinitely and particle-particle collisions are not efficient enough
+to explain the observed limits of these anisotropies. Instead, the
+self-generated wave instabilities can efficiently act to constrain kinetic
+anisotropies, but the existing approaches are simplified and do not provide
+satisfactory explanations. Thus, small deviations from isotropy shown by the
+electron temperature ($T$) in fast solar winds are not explained yet.
+  Aims. This paper provides an advanced quasilinear description of the whistler
+instability driven by the anisotropic electrons in conditions typical for the
+fast solar winds. The enhanced whistler-like fluctuations may constrain the
+upper limits of temperature anisotropy $A \equiv T_\perp /T_\parallel > 1$,
+where $\perp, \parallel$ are defined with respect to the magnetic field
+direction.
+  Methods. Studied are the self-generated whistler instabilities, cumulatively
+driven by the temperature anisotropy and the relative (counter)drift of the
+electron populations, e.g., core and halo electrons. Recent studies have shown
+that quasi-stable states are not bounded by the linear instability thresholds
+but an extended quasilinear approach is necessary to describe them in this
+case.
+  Results. Marginal conditions of stability are obtained from a quasilinear
+theory of the cumulative whistler instability, and approach the quasi-stable
+states of electron populations reported by the observations.The instability
+saturation is determined by the relaxation of both the temperature anisotropy
+and the relative drift of electron populations.",1904.06202v2
+2019-07-24,"Exact Thermodynamic Properties of (1,1/2) Mixed Diamond Chains with Strong Single-Site Anisotropy","The ground states and finite-temperature properties of mixed diamond chains
+with spins 1 and 1/2 are investigated in the limit of strong easy-axis
+anisotropy on the spin-1 sites. Magnetization curves, entropy, specific heat
+and magnetic susceptibility are exactly calculated using the method of
+\v{C}anov\`a et al. [J. Phys.: Condens. Matter 18 4967 (2006)].",1907.10467v1
+2019-11-01,Discrimination of Dark Matter Mass and Velocity Distribution by Directional Detection,"The velocity distribution of dark matter is supposed to be isotropic Maxwell-
+Boltzmann distribution in most cases, however, its anisotropy is suggested by
+some simulations. We investigate conditions to give constraints on the
+anisotropy with directional direct detections.",1911.00170v1
+2020-11-18,On the interplay between magnetic field and anisotropy in holographic QCD,"We investigate the combined effects of anisotropy and a magnetic field in
+strongly interacting gauge theories by the gauge/gravity correspondence. Our
+main motivation is the quark-gluon plasma produced in off-central heavy-ion
+collisions which exhibits large anisotropy in pressure gradients as well as
+large external magnetic fields. We explore two different configurations, with
+the anisotropy either parallel or perpendicular to the magnetic field, focusing
+on the competition and interplay between the two. A detailed study of the RG
+flow in the ground state reveals a rich structure where depending on which of
+the two, anisotropy or magnetic field, is stronger, intermediate geometries
+with approximate AdS$_4\times \mathbb{R}$ and AdS$_3\times \mathbb{R}^2$
+factors arise. This competition is also manifest in the phase structure at
+finite temperature, specifically in the dependence of the chiral transition
+temperature on anisotropy and magnetic field, from which we infer the presence
+of inverse magnetic and anisotropic catalyses of the chiral condensate.
+Finally, we consider other salient observables in the theory, including the
+quark-antiquark potential, shear viscosity, entanglement entropy and the
+butterfly velocity. We demonstrate that they serve as good probes of the
+theory, in particular, distinguishing between the effects of the magnetic field
+and anisotropy in the ground and plasma states. We also find that the butterfly
+velocity, which codifies how fast information propagates in the plasma,
+exhibits a rich structure as a function of temperature, anisotropy and magnetic
+field, exceeding the conformal value in certain regimes.",2011.09474v3
+2021-04-22,Features of the Galactic Cosmic Ray Anisotropy in the Solar Cycle 24 and Solar Minima 23/24 and 24/25,"We study the role of drift effect in the temporal changes of the anisotropy
+of galactic cosmic rays (GCRs) and the influence of the sector structure of the
+heliospheric magnetic field on it. We analyze the GCRs anisotropy in the Solar
+Cycle 24 and solar minimum 23_24 with negative polarity for the period of
+2007-2009 and near minimum 24_25 with positive polarity in 2017-2018 using data
+of global network of Neutron Monitors. We use the harmonic analyses method to
+calculate the radial and tangential components of the anisotropy of GCRs for
+different sectors (plus corresponds to the positive and minus to the negative
+directions) of the heliospheric magnetic field. We compare the analysis of GCRs
+anisotropy using different evaluations of the mean GCRs rigidity related to
+Neutron Monitor observations. Then the radial and tangential components are
+used for characterizing the GCRs modulation in the heliosphere. We show that in
+the solar minimum 23_24 in 2007-2009 when negative, the drift effect is not
+visibly evident in the changes of the radial component, i.e. the drift effect
+is found to produce 4 % change in the radial component of the GCRs anisotropy
+for 2007-2009. Hence the diffusion dominated model of GCRs transport is more
+acceptable in 2007-2009. In turn, near the solar minimum 24_25 in 2017-2018
+when positive, the drift effect is evidently visible and produce 40% change in
+the radial component of the GCRs anisotropy for 2017-2018. So in the period of
+2017-2018 diffusion model with noticeably manifested drift is acceptable. The
+results of this work are in good agreement with the drift theory of GCRs
+modulation, according to which during negative (positive) polarity cycles, a
+drift stream of GCRs is directed toward (away from) the Sun, thus giving rise
+to a 22-year cycle variation of the radial GCRs anisotropy.",2104.11277v1
+2022-02-12,Renormalization group analysis of the finite 2DXY model with fourfold anisotropy: Application to the magnetic susceptibility of a ferromagnetic ultrathin film,"The renormalization group equations describing a finite 2DXY system with
+fourfold anisotropy are solved in two steps, in order to study the magnetic
+transition to paramagnetism in an ultrathin film. First, the equations are
+linearized near the critical coupling $K=J/k_BT=2/\pi$. An exact solution of
+the linearized equations confirms that a finite-size Kosterlitz-Thouless (KT)
+transition occurs in the presence of weak fourfold anisotropy, and that an
+Ising transition occurs for strong anisotropy. The behaviour of a given system
+is determined by the product of an anisotropy parameter and the logarithm of
+the system size. The linearized RG equations are not quantitatively reliable
+across the full temperature range of the finite-size transition, but they
+define the parameter space where a second approach, where the fourfold
+anisotropy is treated as a perturbation, is valid. This perturbative treatment
+provides a quantitative determination of the renormalized exchange coupling,
+vortex density, and anisotropy throughout the transition. In particular, the
+coupling has a universal point of inflection where vortex-antivortex pairs
+unbind (as opposed to a ""universal jump""), and goes to zero asymptotically in
+the paramagnetic state, as is expected for a finite system. These results are
+used to calculate the magnetic susceptibility as the system moves from one
+dominated by spin waves to one dominated by a free vortex gas. The presence of
+anisotropy makes it necessary to include both the susceptibility $\chi_{||}$
+due to fluctuations of the magnitude of the magnetization, and $\chi_\perp$ due
+to angular fluctuations of the magnetization about a fourfold easy axis. A
+comparison to recent measurements of the magnetic susceptibility of ultrathin
+Fe/W(001) films is very encouraging.",2202.06100v2
+2022-02-24,Temperature Anisotropy of the CMBR and the Non-zero Cosmological Constant,"We analyze the effect of a spherically symmetric clump on the anisotropy of
+the cosmic microwave background radiation temperature in the framework of the
+standard model of cosmology with a non-zero cosmological constant $\Lambda$ and
+we show that it weakens the Rees-Sciama effect.",2202.12105v2
+2022-04-18,Tomography of stellar halos: what does anisotropy in a stellar halo tell us?,"The stellar halo of the Milky Way is known to have a highly lumpy structure
+due to the presence of tidal debris and streams accreted from the satellite
+galaxies. The abundance and distribution of these substructures can provide a
+wealth of information on the assembly history of the Milky Way. We use some
+information-theoretic measures to study the anisotropy in a set of Milky
+Way-sized stellar halos from the Bullock & Johnston suite of simulations that
+uses a hybrid approach coupling semi-analytic and N-body techniques. Our
+analysis shows that the whole-sky anisotropy in each stellar halo increases
+with the distance from its centre and eventually plateaus out beyond a certain
+radius. All the stellar halos have a very smooth structure within a radius of
+$\sim 50$ kpc and a highly anisotropic structure in the outskirts. At a given
+radius, the anisotropies at a fixed polar or azimuthal angle have two distinct
+components: (i) an approximately isotropic component and (ii) a component with
+large density fluctuations on small spatial scales. We remove the contributions
+of the substructures and any non-spherical shape of the halo by randomizing the
+polar and azimuthal coordinates of the stellar particles while keeping their
+radial distances fixed. We observe that the fluctuating part of the anisotropy
+is completely eliminated, and the approximately uniform component of the
+anisotropy is significantly reduced after the sphericalization. A comparison
+between the original halos and their sphericalized versions reveals that the
+approximately uniform part of the anisotropy originates from the discreteness
+noise and the non-spherical shape of the halo whereas the substructures
+contribute to the fluctuating part. We show that such distinction between the
+anisotropies has the potential to constrain the shape of the stellar halo and
+its substructures.",2204.08425v2
+2022-07-31,Possible Enhancements of Collective Flow Anisotropy Induced by Uncertainty Relation for Fluid Element,"In the stochastic formulation of viscous hydrodynamics, the velocity of a
+fluid element fluctuates satisfying a similar relation to the
+quantum-mechanical uncertainty relation. Using a non-relativistic toy model, we
+show that the presence of such a velocity fluctuation increases the local
+anisotropy of the momentum distributions of produced hadrons, and thus the
+collective flow parameters such as $v_2$ is emphasized.",2208.00452v1
+2023-03-11,Instability of a plane Poiseuille flow bounded between inhomogeneous anisotropic porous layers,"The linear stability analysis of a plane Poiseuille flow in a channel with
+anisotropic and inhomogeneous porous layers is performed. The effect of
+anisotropy and inhomogeneous permeability on the stability characteristics is
+addressed in detail. The stability characteristics of the anisotropy parameter
+(the ratio of permeability in the streamwise and the transverse direction) and
+the inhomogeneity function are presented in detail",2305.07654v1
+2023-05-25,Detector induced anisotropies on the angular distribution of gravitational wave sources and opportunities of constraining horizon scale anisotropies,"The cosmological principle has been verified using electromagnetic (EM)
+observations. However its verification with high accuracy is challenging due to
+various foregrounds and selection effects, and possible violation of the
+cosmological principle has been reported in the literature. In contrast,
+gravitational wave (GW) observations are free of these foregrounds and related
+selection biases. This may enable future GW experiments to test the
+cosmological principle robustly with full sky distribution of millions of
+standard bright/dark sirens. However, the sensitivities of GW detectors are
+highly anisotropic, resulting in significant instrument induced anisotropies in
+the observed GW catalog. We investigate these instrumental effects for 3rd
+generation detector networks in term of multipoles $a_{\ell m}$ of the observed
+GW source distribution, using Monte Carlo simulations. (1) We find that the
+instrument induced anisotropy primarily exists at the $m=0$ modes on large
+scales ($\ell \lesssim 10$), with amplitude $\langle |a_{\ell 0}|^2 \rangle
+\sim 10^{-3}$ for two detectors (ET-CE) and $\sim 10^{-4}$ for three detectors
+(ET-2CE). This anisotropy is correlated with the sky distribution of
+signal-to-noise ratio (SNR) and localization accuracy. Such anisotropy sets a
+lower limit on the detectable cosmological $a_{\ell 0}$. (2) However, we find
+that the instrument induced anisotropy is efficiently canceled by rotation of
+the Earth in $m\neq 0$ components of $a_{\ell m}$. Therefore $a_{\ell m}$
+($m\neq 0$) are clean windows to detect cosmological anisotropies. (3) We
+investigate the capability of 3rd generation GW experiments to measure the
+cosmic dipole. Through Monte Carlo simulations, we find that cosmic dipole with
+an amplitude of $\sim 10^{-2}$ reported in the literature can be detected/ruled
+out by ET-CE and ET-2CE robustly, through the measurement of $a_{11}$.",2305.15946v2
+2023-08-09,Concave solutions to Finsler $p$-Laplace type equations,"We prove concavity properties for solutions to anisotropic quasi-linear
+equations, extending previous results known in the Euclidean case. We focus the
+attention on nonsmooth anisotropies and in particular we also allow the
+functions describing the anisotropies to be not even.",2308.05069v2
+1993-03-19,Cosmic Variance in CMB Anisotropies: From $1^{\circ}$ to COBE,"Cosmic Microwave Background (CMB) anisotropies that result from quantum
+fluctuations during inflation are explored and the impact of their ``cosmic
+variance'' on the ability to use existing data to probe inflationary models is
+studied. We calculate the rms temperature fluctuation, and its cosmic variance,
+for a number of experiments and for models with primordial power spectra which
+range from $n={1\over 2}$ to $1$. We find: (1) cosmic variance obscures the
+information which can be extracted, so a comparison of the rms temperature
+fluctuation on small scales with the COBE result can fix $n$ to only
+$\approx\pm 0.2$ at best; (2) measurements of the rms fluctuation on
+$1^{\circ}$ scales may not allow one to unambiguously infer the tensor
+contribution to the COBE anisotropy; (3) comparison of this contribution with
+the predictions of inflation are ambiguous if the quadrupole anisotropy alone
+is utilized. We discuss means for minimizing the uncertainty due to cosmic
+variance in comparisons between experiments.",9303009v2
+1994-01-04,Small-Scale Cosmic Microwave Background Anisotropies as a Probe of the Geometry of the Universe,"We perform detailed calculations of cosmic microwave background (CMB)
+anisotropies in a CDM-dominated open universe with primordial adiabatic density
+perturbations for a variety of reionization histories. We show that to a great
+extent, the CMB anisotropies depend only on the geometry of the Universe, which
+in a matter dominated universe is determined by $\Omega$, and the optical depth
+to the surface of last scattering. In particular, the location of the primary
+Doppler peak depends primarily on $\Omega$ and is fairly insensitive to the
+other unknown parameters, such as $\Omega_b$, $h$, $\Lambda$, and the shape of
+the power spectrum. Therefore, measurements of CMB anisotropies on small scales
+may be used to determine $\Omega$.",9401003v1
+1994-09-27,The Effect of Gravitational Scattering on the Anisotropy of the Cosmic Background Radiation,"The homogeneity of the cosmic microwave background radiation (CBR) is one of
+the most severe constraint for theories of the structure formation in the
+universe. We investigated the effect of the gravitational scattering (lensing)
+of galaxies, clusters of galaxies, and superclusters on the anisotropy of the
+CBR by numerical simulations. Although this effect was thought to be
+unimportant, we found that the gravitational scatterings by superclusters can
+significantly reduce the anisotropy of the CBR. We took into account the
+exponential growth of the distance between two rays due to multiple
+scatterings. The bending angle of each ray grows through the random walk
+process. On the other hand, difference between two rays grows exponentially
+while it is small. This exponential growth is caused by coherent scatterings
+that two rays suffer, and was neglected in the previous studies. The
+gravitational scattering by superclusters reduces the observed temperature
+anisotropy of the CBR at present time approximately by 40--60 $\%$ from that at
+the recombination time for angular scale up to a few degrees if the
+supercluster were formed at $z=$2--4.",9409069v1
+1995-11-27,Concepts in CMB Anisotropy Formation,"These lecture notes form a primer on the theory of cosmic microwave
+background (CMB) anisotropy formation. With emphasis on conceptual aspects
+rather than technical issues, we examine the physical foundations of anisotropy
+evolution in relativistic kinetic and perturbation theory as well as the
+manifestation of these principles in primary and secondary anisotropies. We
+discuss gauge choice and gauge invariance and their use in understanding the
+CMB. Acoustic, gravitational redshift and ionization effects have robust
+signatures in the CMB spectrum and may allow determination of classical
+cosmological parameters as well as reveal general distinctions between models
+for structure formation. We develop the tight and weak coupling approximations
+as analytic tools to help understand these effects and the robustness of their
+signatures.",9511130v1
+1996-06-16,Sub-degree Scale Microwave Anisotropies from Cosmic Defects,"If current ideas about unified field theories are correct, macroscopic cosmic
+defects may well exist. The observation of such an entity would have enormous
+significance for our understanding of fundamental physics. This paper points
+out a novel observable signature of cosmic texture and global monopoles, namely
+strong hot spots in the cosmic microwave anisotropy pattern on subdegree
+scales. This signal should be readily detectable by the next generation of
+anisotropy mapping experiments. The signature arises from overdensities in the
+photon-baryon fluid generated by the gravitational attraction of the defects.
+The angular power spectrum of the anisotropy fluctuations on subdegree scales
+is also calculated, for cosmic string, global monopoles, and texture.",9606087v1
+1996-09-04,Fokker-Planck Models of Star Clusters with Anisotropic Velocity Distributions. II. Post-Collapse Evolution,"The evolution of spherical single-mass star clusters driven by two-body
+relaxation was followed beyond core collapse by numerically solving the
+orbit-averaged Fokker-Planck equation in energy--angular momentum space. The
+heating effect by three-body binaries was incorporated in the Fokker-Planck
+models. The development of velocity anisotropy after the core collapse is
+discussed in detail. The anisotropy in the outer regions continues to increase
+slowly after the collapse. In clusters comprising a relatively small number of
+stars ($N \ltsim 10000$), the post-collapse expansion is nearly self-similar
+and the anisotropy at each of inner Lagrangian radii is nearly constant. In
+clusters comprising a larger number of stars ($N \gtsim 10000$), gravothermal
+oscillations occur and the anisotropy at each of the inner radii oscillates
+with the core oscillations. There is no qualitative difference in the nature of
+the gravothermal oscillations between the isotropic and anisotropic
+Fokker-Planck models.",9609025v1
+1996-11-27,Anisotropy in the Microwave Sky: Results from the First Flight of BAM,"Results are reported from the first flight of a new balloon-borne instrument,
+BAM (Balloon-borne Anisotropy Measurement), designed to search for cosmic
+microwave background (CMB) anisotropy. The instrument uses a cryogenic
+differential Fourier transform spectrometer to obtain data in five spectral
+channels whose central frequencies lie in the range 3.7 cm^{-1} to 8.5 cm^{-1}.
+The spectrometer is coupled to an off-axis prime focus telescope; the
+combination yields difference spectra of two regions on the sky defined by
+0\fdg 7 FWHM beams separated by 3\fdg 6. Single differences obtained at ten sky
+positions show statistically significant fluctuations. Assuming Gaussian
+correlated anisotropy, for the band average 3.1 cm^{-1} to 9.2 cm^{-1}, one
+finds $\Delta T/T = 3.1^{+3.1}_{1.1}\times 10^{-5}$ (90% confidence interval)
+for a correlation angle of 1\fdg 2. This corresponds to $Q_{flat} =
+35.9^{17.7}_{6.3} \mu K$ (1\sigma).",9611225v1
+1997-01-13,Constraints on a Primordial Magnetic Field,"We derive an upper limit of $B_0<3.4\times 10^{-9}(\Omega_0h_{50}^2)^{1/2}$
+Gauss on the present strength of any primordial homogeneous magnetic field. The
+microwave background anisotropy created by cosmological magnetic fields is
+calculated in the most general flat and open anisotropic cosmologies containing
+expansion-rate and 3-curvature anisotropies. Our limit is derived from a
+statistical analysis of the 4-year Cosmic Background Explorer data for
+anisotropy patterns characteristic of homogeneous anisotropy averaged over all
+possible sky orientations with respect to the COBE receiver. The limits we
+obtain are considerably stronger than those imposed by primordial
+nucleosynthesis and ensure that other magnetic field effects on the microwave
+background structure are unobservably small.",9701063v1
+1997-02-24,Open inflation models and gravitational wave anisotropies in the CMB,"We study the large scale power spectrum of gravitational wave perturbations
+of the microwave background in the context of single-bubble open inflation
+models. We compute the ratio of tensor to scalar contributions to the CMB
+anisotropies as a function of $\Omega_0$, the spectral index $n_S$ and the
+tunneling parameter $2\pi GS_1/H$. We find that gravitational wave anisotropies
+can be very large at small values of this tunneling parameter. We also consider
+the contribution of supercurvature and bubble wall modes and find constraints
+on the parameters of open inflation models from the observed temperature
+anisotropies of the CMB. We show that the induced gravity and open hybrid
+scenarios are compatible with present observations for a reasonable range of
+parameters.",9702211v2
+1997-02-26,CMB anisotropies caused by gravitational waves: A parameter study,"Anisotropies in the cosmic microwave background radiation due to gravity
+waves are investigated. An initial spectrum of gravity waves may have been
+induced during an epoch of inflation. We study the propagation of such a
+spectrum in a Friedmann background of hot and cold dark matter, radiation and
+(possibly) a cosmological constant. We finally calculate its imprint as
+anisotropies on the cosmic microwave background. We also take into account that
+massless particles can source gravity waves by their anisotropic stresses. We
+consider general mixed dark matter models with and without cosmological
+constant. For a given, scale invariant input spectrum of gravity we determine
+the dependence of the resulting spectrum of CMB anisotropies on the different
+model parameters.",9702226v2
+1997-02-27,Cosmic Microwave Background anisotropies from second order gravitational perturbations,"This paper presents a complete analysis of the effects of second order
+gravitational perturbations on Cosmic Microwave Background anisotropies, taking
+explicitly into account scalar, vector and tensor modes. We also consider the
+second order perturbations of the metric itself obtaining them, for a universe
+dominated by a collision-less fluid, in the Poisson gauge, by transforming the
+known results in the synchronous gauge. We discuss the resulting second order
+anisotropies in the Poisson gauge, and analyse the possible relevance of the
+different terms. We expect that, in the simplest scenarios for structure
+formation, the main effect comes from the gravitational lensing by scalar
+perturbations, that is known to give a few percent contribution to the
+anisotropies at small angular scales.",9702234v2
+1997-05-13,Cosmology with Sunyaev-Zeldovich observations from space,"In order to assess the potential of future microwave anisotropy space
+experiments for detecting clusters by their Sunyaev-Zeldovich (SZ) thermal
+effect, we have simulated maps of the large scale distribution of their Compton
+parameter $y$ and of the temperature anisotropy $\Delta T/T$ induced by their
+proper motion. Our model is based on a predicted distribution of clusters per
+unit redshift and flux density using a Press-Schecter approach. These maps were
+used to create simulated microwave sky by adding them to the microwave
+contributions of the emissions of our Galaxy and the primary Cosmic Microwave
+Background (CMB) anisotropies. In order to simulate measurements representative
+of what current technology should achieve, ``observations'' were performed
+according to the instrumental characteristics of the COBRAS/SAMBA space
+mission. We then analyzed the resulting $y$ and $\Delta T/T$ maps which now
+include both the primary anisotropies and those superimposed due to cluster
+motions.",9705092v1
+1997-06-25,"The Scalar, Vector and Tensor Contributions to CMB anisotropies from Cosmic Defects","Recent work has emphasised the importance of vector and tensor contributions
+to the large scale microwave anisotropy fluctuations produced by cosmic
+defects. In this paper we provide a general discussion of these contributions,
+and how their magnitude is constrained by the fundamental assumptions of
+causality, scaling, and statistical isotropy. We discuss an analytic model
+which illustrates and explains how the ratios of isotropic and anisotropic
+scalar, vector and tensor microwave anisotropies are determined. This provides
+a check of the results from large scale numerical simulations, confirming the
+numerical finding that vector and tensor modes provide substantial
+contributions to the large angle anisotropies. This leads to a suppression of
+the scalar normalisation and consequently of the Doppler peaks.",9706250v2
+1997-09-09,A Complete Treatment of CMB Anisotropies in a FRW Universe,"We generalize the total angular momentum method for computing Cosmic
+Microwave Background anisotropies to Friedman-Robertson-Walker (FRW) spaces
+with arbitrary geometries. This unifies the treatment of temperature and
+polarization anisotropies generated by scalar, vector and tensor perturbations
+of the fluid, seed, or a scalar field, in a universe with constant comoving
+curvature. The resulting formalism generalizes and simplifies the calculation
+of anisotropies and, in its integral form, allows for a fast calculation of
+model predictions in linear theory for any FRW metric.",9709066v2
+1997-10-01,Correlation Functions of CMB Anisotropy and Polarization,"We give a full analysis of the auto- and cross-correlations between the
+Stokes parameters of the cosmic microwave background. In particular, we derive
+the windowing function for an antenna with Gaussian response in polarization
+experiment, and construct correlation function estimators corrected for
+instrumental noise. They are applied to calculate the signal to noise ratios
+for future anisotropy and polarization measurements. While the
+small-angular-scale anisotropy-polarization correlation would be likely
+detected by the MAP satellite, the detection of electric and magnetic
+polarization would require higher experimental sensitivity. For
+large-angular-scale measurements such as the being planned SPOrt/ISS, the
+expected signal to noise ratio for polarization is greater than one only for
+reionized models with high reionization redshifts, and the ratio is less for
+anisotropy-polarization correlation. Correlation and covariance matrices for
+likelihood analyses of ground-based and satellite data are also given.",9710012v2
+1998-03-17,Secondary CMB anisotropies in a universe reionized in patches,"In a universe reionized in patches, the Doppler effect from Thomson
+scattering off free electrons generates secondary cosmic microwave background
+(CMB) anisotropies. For a simple model with small patches and late
+reionization, we analytically calculate the anisotropy power spectrum. Patchy
+reionization can, in principle, be the main source of anisotropies on arcminute
+scales. On larger angular scales, its contribution to the CMB power spectrum is
+a small fraction of the primary signal and is only barely detectable in the
+power spectrum with even an ideal, i.e. cosmic variance limited, experiment and
+an extreme model of reionization. Consequently patchy reionization is unlikely
+to affect cosmological parameter estimation from the acoustic peaks in the CMB.
+Its detection on small angles would help determine the ionization history of
+the universe, in particular the typical size of the ionized region and the
+duration of the reionization process.",9803188v1
+1998-07-01,Anisotropy of the sky distribution of gamma-ray bursts,"The isotropy of gamma-ray bursts collected in Current BATSE catalog is
+studied. It is shown that the quadrupole term being proportional to $\sim \sin
+2b \sin l$ is non-zero with a probability 99.9%. The occurrence of this
+anisotropy term is then confirmed by the binomial test even with the
+probability 99.97 %. Hence, the sky distribution of all known gamma-ray bursts
+is anisotropic. It is also argued that this anisotropy cannot be caused
+exclusively by instrumental effects due to the nonuniform sky exposure of BATSE
+instrument. Separating the GRBs into short and long subclasses, it is shown
+that the short ones are distributed anisotropically, but the long ones seem to
+be distributed still isotropically. The character of anisotropy suggests that
+the cosmological origin of short GRBs further holds, and there is no evidence
+for their Galactical origin.",9807006v1
+1998-07-04,The Anisotropy of Cosmic Ray Arrival Directions around 10$^{18}$eV,"Anisotropy in the arrival directions of cosmic rays with energies above
+10$^{17}$eV is studied using data from the Akeno 20 km$^2$ array and the Akeno
+Giant Air Shower Array (AGASA), using a total of about 117,000 showers observed
+during 11 years. In the first harmonic analysis, we have found strong
+anisotropy of $\sim$ 4% around 10$^{18}$eV, corresponding to a chance
+probability of 0.2%. With two dimensional analysis in right ascension and
+declination, this anisotropy is interpreted as an excess of showers near the
+directions of the Galactic Center and the Cygnus region.",9807045v2
+1998-10-19,Anisotropy of Ultra High Energy Cosmic Rays in the Dark Matter Halo Model,"The harmonic analysis of anisotropy of Ultra High Energy Cosmic Rays is
+performed for the Dark Matter halo model. In this model the relic superheavy
+particles comprise part of the Dark Matter and are concentrated in the Galactic
+halo. The Ultra High Energy Cosmic Rays are produced by the decays of these
+particles. Anisotropy is caused by the non-central position of the Sun in the
+Galactic halo. The calculated anisotropy is in reasonable agreement with the
+AGASA data. For more precise test of the model a comparison of fluxes in the
+directions of the Galactic Center and Anticenter is needed.",9810277v3
+1998-11-10,Observational Constraints on Microwave Anisotropy from Point Sources,"Applying basic physical principles to recent observational results, we derive
+upper and lower limits on microwave anisotropy from point sources over the
+range of frequencies 10-1000 GHz. We examine the level of noise in the
+observations as a possible indication of source confusion at subarcminute
+scales. We also derive an upper limit on microwave anisotropy caused by the
+sources responsible for the Far-Infrared Background radiation detected in FIRAS
+data. Our upper limit on point source confusion of DeltaT/T=10^{-5} for a 10'
+beam at 100 GHz would cause severe foreground contamination for CMB anisotropy
+observations, although the actual contamination level is probably much lower.
+This upper limit constrains the long-feared possibility of an undetected
+population of sources with emission peaking near 100 GHz. Source detections
+closer to 100 GHz are needed to improve our knowledge of galaxy evolution at
+high redshift and to predict the level of point source confusion.",9811148v1
+1999-01-17,The Gravitational-Wave contribution to the CMB anisotropies,"We study the possible contribution of a stochastic gravitational wave
+background to the anisotropy of the cosmic microwave background (CMB) in cold
+and mixed dark matter (CDM and MDM) models. We test this contribution against
+recent detections of CMB anisotropy at large and intermediate angular scales.
+Our likelihood analysis indicates that models with blue power spectra ($n
+\simeq 1.2$) and a tensor to the scalar quadrupole ratio of $R = C_2^T /C_2^S
+\sim 2$ are most consistent with the anisotropy data considered here. We find
+that by including the possibility of such background in CMB data analysis it
+can drastically alter the conclusion on the remaining cosmological parameters.",9901220v1
+1999-04-19,An almost isotropic cosmic microwave temperature does not imply an almost isotropic universe,"In this letter we will show that, contrary to what is widely believed, an
+almost isotropic cosmic microwave background (CMB) temperature does not imply
+that the universe is ``close to a Friedmann-Lemaitre universe''. There are two
+important manifestations of anisotropy in the geometry of the universe, (i) the
+anisotropy in the overall expansion, and (ii) the intrinsic anisotropy of the
+gravitational field, described by the Weyl curvature tensor, although the
+former usually receives more attention than the latter in the astrophysical
+literature. Here we consider a class of spatially homogeneous models for which
+the anisotropy of the CMB temperature is within the current observational
+limits but whose Weyl curvature is not negligible, i.e. these models are not
+close to isotropy even though the CMB temperature is almost isotropic.",9904252v1
+1999-12-01,Limits on Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array,"We have used the Berkeley-Illinois-Maryland-Association (BIMA) millimeter
+array outfitted with sensitive cm-wave receivers to search for Cosmic Microwave
+Background (CMB) anisotropies on arcminute scales. The interferometer was
+placed in a compact configuration which produces high brightness sensitivity,
+while providing discrimination against point sources. Operating at a frequency
+of 28.5 GHz, the FWHM primary beam of the instrument is 6.6 arcminutes. We have
+made sensitive images of seven fields, five of which where chosen specifically
+to have low IR dust contrast and be free of bright radio sources. Additional
+observations with the Owens Valley Radio Observatory (OVRO) millimeter array
+were used to assist in the location and removal of radio point sources.
+Applying a Bayesian analysis to the raw visibility data, we place limits on CMB
+anisotropy flat-band power Q_flat = 5.6 (+3.0 -5.6) uK and Q_flat < 14.1 uK at
+68% and 95% confidence. The sensitivity of this experiment to flat band power
+peaks at a multipole of l = 5470, which corresponds to an angular scale of
+approximately 2 arcminutes. The most likely value of Q_flat is similar to the
+level of the expected secondary anisotropies.",9912010v1
+1999-12-01,On the existence of the intrinsic anisotropies in the angular distributions of gamma-ray bursts,"This articles is concerned primarily with the intrinsic anisotropy in the
+angular distribution of 2281 gamma-ray bursts (GRBs) collected in Current BATSE
+Gamma-Ray Burst Catalog until the end of year 1998, and, second, with intrinsic
+anisotropies of three subclasses (""short"", ""intermediate"", ""long"") of GRBs.
+Testing based on spherical harmonics of each class, in equatorial coordinates,
+is presented. Because the sky exposure function of BATSE instrument is not
+dependent on the right ascension $\alpha$, any non-zero spherical harmonic
+proportional either to $P_n^m(\sin \delta) \sin m \alpha$ or to $P_n^m(\sin
+\delta) \cos m\alpha$ with $m \neq 0$ ($\delta$ is the declination),
+immediately indicates an intrinsic non-zero term. It is a somewhat surprising
+result that the ""intermediate"" subclass shows an intrinsic anisotropy at the
+$97\%$ significance level caused by the high non-zero $P_3^1(\sin \delta) \sin
+m \alpha$ harmonic. The remaining two subclasses, and the full sample of GRBs,
+remain isotropic.",9912037v1
+2000-06-24,Ultra High Energy Cosmic Rays: propagation in the Galaxy and anisotropy,"We considered propagation of Ultra High Energy Cosmic Rays (UHECR) through
+the galaxy. We investigated models with sources of UHECR distributed in the
+same way as Cold Dark Matter (CDM) in a self-consistent way, taking into
+account both extra-galactic and Galactic contributions. Using a very simple toy
+model of galactic magnetic field we showed that in the case of galactic origin
+of UHECRs the anisotropy can reach considerable values. In the case of
+extragalactic UHECRs origin the anisotropy appears to be non-vanishing only for
+electron and photon components due to synchrotron losses, but it hardly can be
+reassured. The reason is an extremely low flux of UHE electrons and a too low
+level of gamma-ray anisotropy.",0006349v3
+2001-12-01,Archeops: A balloon experiment to measure CMB anisotropies with a broad range of angular sizes,"The Cosmic Microwave Background Radiation is the oldest photon radiation that
+can be observed, having been emitted when the Universe was about 300,000 year
+old. It is a blackbody at 2.73 K, and is almost perfectly isotropic, the
+anisotropies being about one part to 100,000. However, these anisotropies,
+detected by the COBE satellite in 1992, constrain the cosmological parameters
+such as the curvature of the Universe.
+  Archeops is a balloon-borne experiment designed to map these anisotropies.
+The instrument is composed of a 1.5 m telescope and bolometers cooled at 85 mK
+to detect radiation between 150 and 550 GHz. To lower atmosphere parasitic
+signal, the instrument is lifted at 32 km altitude with a stratospheric balloon
+during the arctic night. This instrument is also a preparation for the Planck
+satellite mission, as its design is similar.
+  We discuss here the results of the first scientific flight from Esrange (near
+Kiruna, Sweden) to Russia on January 29th 2001, which led to a 22 %
+(sub)millimetre sky coverage unprecedented at this resolution.",0112012v1
+2002-03-07,Cosmic Microwave Background anisotropies beyond the third peak,"Forthcoming CMB experiments will allow us to accurately investigate the power
+spectrum at very small scales ($\ell > 1000$). We predict the level of the
+primary anisotropies, given the actual CMB measurements. The secondary
+anisotropies generated after matter-radiation decoupling contribute additional
+power in the tail of the CMB power spectrum. Together with the primary
+anisotropies, we compute the predicted power spectra for three dominant
+secondary effects induced by photon scattering. We predict these secondary
+contributions in flat cosmological models for parameters in agreement (to
+$2\sigma$) with the values allowed by current parameter estimates.",0203112v2
+2002-10-31,CMB Temperature and Polarization Anisotropy Fundamentals,"The tremendous experimental progress in cosmic microwave background (CMB)
+temperature and polarization anisotropy studies over the last few years has
+helped establish a standard paradigm for cosmology at intermediate epochs and
+has simultaneously raised questions regarding the physical processes at the two
+opposite ends of time. What is the physics behind the source of structure in
+the universe and the dark energy that is currently accelerating its expansion?
+We review the acoustic phenomenology that forms the cornerstone of the standard
+cosmological model and discuss internal consistency relations which lend
+credence to its interpretation. We discuss future milestones in the study of
+CMB anisotropy that have implications for inflationary and dark energy models.
+These include signatures of gravitational waves and gravitational lensing in
+the polarization fields and secondary temperature anisotropy from the transit
+of CMB photons across the large-scale structure of the universe.",0210696v1
+2003-08-27,The Anisotropy Search Program For the Pierre Auger Observatory,"The Pierre Auger Southern Observatory in Argentina has begun taking data as
+it is being developed up to a final enclosed area of 3000 square kilometres. A
+key aspect of the project is to provide information on the origin of the
+highest energy cosmic rays through understanding the arrival directions of
+those particles. To avoid claims of a spurious anisotropy detection because
+trials have not been properly accounted, the Auger Collaboration has agreed 'a
+priori' to the analysis prescription presented here. It specifies the
+following:
+  1. The accumulation time for the (future) data set to be analyzed.
+  2. The anisotropy 'targets', each assigned a chance probability level.
+  3. The analysis procedure for each trial.
+  A positive result will be claimed for any target search only if its chance
+probability is less than its assigned level. The levels are chosen so that the
+total chance probability for one or more positive results is 0.001.
+  Exploratory searches beyond this prescription will be encouraged, but the
+Auger Collaboration will not assign any confidence level to anisotropies that
+may be discovered that way. Any such discovery would identify a good target for
+a prescription to be used with a subsequent Auger data set.",0308494v1
+2003-09-29,Interpretation of the Global Anisotropy in the Radio Polarizations of Cosmologically Distant Sources,"We present a detailed statistical study of the observed anisotropy in radio
+polarizations from distant extragalactic objects. This anisotropy was earlier
+found by Birch (1982) and reconfirmed by Jain and Ralston (1999) in a larger
+data set. A very strong signal was seen after imposing the cut
+$|RM-\bar{RM}|>6$ rad/m$^2$, where $RM$ is the rotation measure and $\bar{RM}$
+its mean value. In this paper we show that there are several indications that
+this anisotropy cannot be attributed to bias in the data.
+  We also find that a generalized statistic shows a very strong signal in the
+entire data without imposing the RM dependent cut. Finally we argue that an
+anisotropic background pseudoscalar field can explain the observations.",0309776v2
+2004-03-15,Anisotropies in the Cosmic Microwave Background,"The linear anisotropies in the temperature of the cosmic microwave background
+(CMB) radiation and its polarization provide a clean picture of fluctuations in
+the universe some 370 kyr after the big bang. Simple physics connects these
+fluctuations with those present in the ultra-high-energy universe, and this
+makes the CMB anisotropies a powerful tool for constraining the fundamental
+physics that was responsible for the generation of structure. Late-time effects
+also leave their mark, making the CMB temperature and polarization useful
+probes of dark energy and the astrophysics of reionization. In this review we
+discuss the simple physics that processes primordial perturbations into the
+linear temperature and polarization anisotropies. We also describe the role of
+the CMB in constraining cosmological parameters, and review some of the
+highlights of the science extracted from recent observations and the
+implications of this for fundamental physics.",0403344v1
+2004-04-13,Angular Power Spectrum Estimation of Cosmic Ray Anisotropies with Full or Partial Sky Coverage,"We study the angular power spectrum estimate in order to search for large
+scale anisotropies in the arrival directions distribution of the highest-energy
+cosmic rays. We show that this estimate can be performed even in the case of
+partial sky coverage and validated over the full sky under the assumption that
+the observed fluctuations are statistically spatial stationary. If this
+hypothesis - which can be tested directly on the data - is not satisfied, it
+would prove, of course, that the cosmic ray sky is non isotropic but also that
+the power spectrum is not an appropriate tool to represent its anisotropies,
+whatever the sky coverage available. We apply the method to simulations of the
+Pierre Auger Observatory, reconstructing an input power spectrum with the
+Southern site only and with both Northern and Southern ones. Finally, we show
+the improvement that a full-sky observatory brings to test an isotropic
+distribution, and we discuss the sensitivity of the Pierre Auger Observatory to
+large scale anisotropies.",0404253v2
+2004-06-16,Statistical Isotropy of the Wilkinson Microwave Anisotropy Probe Data: A Bipolar Power Spectrum Analysis,"The statistical expectation values of the temperature fluctuations of the
+Cosmic Microwave Background (CMB) are assumed to be preserved under rotations
+of the sky. We investigate the Statistical Isotropy (SI) of the CMB anisotropy
+maps recently measured by the Wilkinson Microwave Anisotropy Probe (WMAP) using
+Bipolar Power Spectrum (BiPS) proposed in [Hajian & Souradeep 2003]. The method
+can probe specific regions in multipole space using appropriate window
+functions. The BiPS is estimated for full sky CMB anisotropy maps based on the
+first year WMAP data using a range of window functions. The BiPS spectra
+computed for both full sky maps for all our window functions are consistent
+with zero, roughly within $2 \sigma$. The null BiPS results may be interpreted
+as an absence of strong violation of statistical isotropy in the first-year
+WMAP data on angular scales larger than that corresponding to $l\sim60$.
+However, pending a careful direct comparison, our results do not necessarily
+conflict with the specific SI related anomalies reported using other
+statistical tests.",0406354v2
+2005-02-12,Statistical isotropy of CMB anisotropy from WMAP,"The statistical expectation values of the temperature fluctuations of cosmic
+microwave background (CMB) are assumed to be preserved under rotations of the
+sky. We investigate the statistical isotropy of the CMB anisotropy maps
+recently measured by the Wilkinson Microwave Anisotropy Probe (WMAP) using
+bipolar spherical harmonic power spectrum proposed in Hajian & Souradeep 2003.
+The Bipolar Power Spectrum (BiPS) is estimated for the full sky CMB anisotropy
+maps of the first year WMAP data. The method allows us to isolate regions in
+multipole space and study each region independently. This search shows no
+evidence for violation of statistical isotropy in the first-year WMAP data on
+angular scales larger than that corresponding to l~60.",0502248v1
+2005-04-01,CMB Anisotropy Due to Tangled magnetic fields in re-ionized models,"Primordial tangled cosmological Magnetic Fields source rotational velocity
+perturbations of the baryon fluid, even in the post-recombination universe.
+These vortical modes inturn leave a characteristic imprint on the temperature
+anisotropy of the Cosmic Microwave Background (CMB), if the CMB photons can be
+re-scatterred after recombination. Observations from WMAP indicate that the
+Universe underwent a relatively early re-ionization ($z_{ri} \sim 15$), which
+does indeed lead to a significant optical depth for re-scattering of CMB
+photons after the re-ionization epoch. We compute the resulting additional
+temperature anisotropies, induced by primordial magnetic fields in the
+post-recombination universe. We show that in models with early re-ionization, a
+nearly scale-invariant spectrum of tangled magnetic fields which redshift to a
+present value of $B_0 \sim 3 \times 10^{-9}$ Gauss, produce vector mode
+perturbations which in turn induce additional temperature anisotropy of about
+0.3 to 0.4 $ \mu$K over very small angular scales, with $ l$ upto $\sim 10000 $
+or so.",0504007v1
+2005-07-21,Coverage and large scale anisotropies estimation methods for the Pierre Auger Observatory,"When searching for anisotropies in the arrival directions of Ultra High
+Energy Cosmic Rays, one must estimate the number of events expected in each
+direction of the sky in the case of a perfect isotropy. We present in this
+article a new method, developed for the Auger Observatory, based on a smooth
+estimate of the zenith angle distribution obtained from the data itself (which
+is essentially unchanged in the case of the presence of a large scale
+anisotropy pattern). We also study the sensitivity of several methods to detect
+large-scale anisotropies in the cosmic ray arrival direction distribution :
+Rayleigh analysis, dipole fitting and angular power spectrum estimation.",0507517v1
+2005-09-26,Separate the Tensor Perturbation From the CMB Temperature Anisotropy Power Spectrum,This paper has been withdrawn.,0509753v3
+2005-09-27,A universal density slope - velocity anisotropy relation,"One can solve the Jeans equation analytically for equilibrated dark matter
+structures, once given two pieces of input from numerical simulations. These
+inputs are 1) a connection between phase-space density and radius, and 2) a
+connection between velocity anisotropy and density slope, the \alpha-\beta
+relation. The first (phase-space density v.s. radius) has been analysed through
+several different simulations, however the second (\alpha-\beta relation) has
+not been quantified yet. We perform a large set of numerical experiments in
+order to quantify the slope and zero-point of the \alpha-\beta relation. When
+combined with the assumption of phase-space being a power-law in radius this
+allows us to conclude that equilibrated dark matter structures indeed have zero
+central velocity anisotropy, central density slope of \alpha_0 = -0.8, and
+outer anisotropy of approximately \beta_\infinity = 0.5.",0509799v1
+2005-10-05,Did WMAP see Moving Local Structures?,"The divergence of the momentum density field of the large scale structure
+generates a secondary anisotropy contribution to the Cosmic Microwave
+Background (CMB). While the effect is best described as a non-linear extension
+to the well-known integrated Sachs-Wolfe effect, due to mathematical
+coincidences, the anisotropy contribution is also described as the lensing of
+the dipole seen in the rest-frame of a moving mass. Given the closeness, there
+is a remote possibility that local concentrations of mass in the form of the
+Great Attractor and the Shapley concentration generate large angular scale
+fluctuations in CMB and could potentially be responsible, at least partly, for
+some of the low-multipole anomalies in WMAP data. While the local anisotropy
+contribution peaks at low multipoles, for reasonable models of the mass and
+velocity distributions associated with local super structures we find that the
+amplitude of temperature anisotropies is at most at a level of 10$^{-2}$ $\mu$K
+and is substantially smaller than primordial fluctuations. It is extremely
+unlikely that the momentum density of local mass concentrations is responsible
+for any of the large angular scale anomalies in WMAP data.",0510137v1
+2005-10-12,CMB Temperature Anisotropy Quadrupole Generated by Tensor Perturbation,This paper has been withdrawn.,0510355v2
+2005-10-21,The velocity anisotropy - density slope relation,"One can solve the Jeans equation analytically for equilibrated dark matter
+structures, once given two pieces of input from numerical simulations. These
+inputs are 1) a connection between phase-space density and radius, and 2) a
+connection between velocity anisotropy and density slope, the \alpha-\beta
+relation. The first (phase-space density v.s. radius) has already been analysed
+through several different simulations, however the second (\alpha-\beta
+relation) has not been quantified yet. We perform a large set of numerical
+experiments in order to quantify the slope and zero-point of the \alpha-\beta
+relation. We find strong indication that the relation is indeed an attractor.
+When combined with the assumption of phase-space being a power-law in radius,
+this allows us to conclude that equilibrated dark matter structures indeed have
+zero central velocity anisotropy \beta_0 = 0, central density slope of \alpha_0
+= -0.8, and outer anisotropy of \beta_\infty = 0.5.",0510656v1
+2005-10-24,Anisotropic thermal emission from magnetized neutron stars,"The thermal emission from isolated neutron stars is not well understood. The
+X-ray spectrum is very close to a blackbody but there is a systematic optical
+excess flux with respect to the extrapolation to low energy of the best
+blackbody fit. This fact, in combination with the observed pulsations in the
+X-ray flux, can be explained by anisotropies in the surface temperature
+distribution.We study the thermal emission from neutron stars with strong
+magnetic fields in order to explain the origin of the anisotropy. We find
+(numerically) stationary solutions in axial symmetry of the heat
+transportequations in the neutron star crust and the condensed envelope. The
+anisotropy in the conductivity tensor is included consistently. The presence of
+magnetic fields of the expected strength leads to anisotropy in the surface
+temperature. Models with toroidal components similar to or larger than the
+poloidal field reproduce qualitatively the observed spectral properties and
+variability of isolated neutron stars. Our models also predict spectral
+features at energies between 0.2 and 0.6 keV.",0510684v2
+2005-10-28,Search for Global Metric Anisotropy in Type Ia Supernova Data,"We examine the Type 1a supernova data in order to determine if it shows any
+signal of large scale anisotropy. The anisotropy is modelled by an extended
+G\""{o}del metric, which incorporates expansion along with rotation. The model
+is smoothly connected to the usual FRW type, while expressing anisotropic
+metric effects depending on certain parameters. We find no significant signal
+of anisotropy in the data. We obtain bounds on an anisotropic redshift versus
+magnitude relationship, and accompanying parameters of the G\""{o}del-Obukhov
+metric.",0510803v3
+2006-07-07,Angular distribution of satellite galaxies from the Sloan Digital Sky Survey Data Release 4,"We explore the angular distribution of two samples of satellite galaxies
+orbiting isolated hosts extracted from the Sloan Digital Sky Survey Data
+Release 4. We find a clear alignment of the satellites along the major axis of
+their hosts when restricting the analysis to red hosts. The anisotropy is most
+pronounced for red satellites of red hosts. We find that the distribution of
+the satellites about blue, isolated hosts is consistent with isotropy. We show
+that under the assumption that the true, underlying distribution of satellites
+of blue hosts exhibits the same anisotropy as the satellites of red hosts, the
+sample of blue hosts is too small to measure this anisotropy at a
+statistically-significant level. The anisotropy that we detect for satellites
+about red primaries is independent of the projected radius. In particular, it
+is evident at large projected distances from primaries (300 < r_p < 500 kpc).",0607139v1
+2006-08-25,The r-Process in the Proto-Neutron-Star Winds with Anisotropic Neutrino Emission,"The astrophysical origin of the r-process nuclei is still unknown. Even the
+most promising scenario, the neutrino-driven winds from a nascent neutron star,
+encounters severe difficulties in obtaining requisite entropy and short dynamic
+timescale for the r-process. In this study, the effect of anisotropy in
+neutrino emission from a proto-neutron star surface is examined with
+semi-analytic neutrino-driven wind models. The increase of neutrino number
+density in the wind owing to the anisotropy is modeled schematically by
+enhancing the effective neutrino luminosity. It is shown that the neutrino
+heating rate from neutrino-antineutrino pair annihilation into
+electron-positron pairs can significantly increase owing to the anisotropy and
+play a dominant role for the heating of wind material. A factor of five
+increase in the effective neutrino luminosity results in 50% higher entropy and
+a factor of ten shorter dynamic timescale owing to this enhanced neutrino
+heating. The nucleosynthesis calculations show that this change is enough for
+the robust r-process, producing the third abundance peak A = 195 and beyond.
+Future multi-dimensional studies with accurate neutrino transport will be
+needed if such anisotropy relevant for the current scenario (more than a factor
+of a few) is realized during the wind phase (~1-10 s).",0608539v1
+2006-09-29,Separating the Weak Lensing and Kinetic SZ Effects from CMB Temperature Maps,"A new generation of CMB experiments will soon make sensitive high resolution
+maps of the microwave sky. At angular scales less than $\sim$10 arcminutes,
+most CMB anisotropies are generated at z $< 1000$, rather than at the surface
+of last scattering. Therefore, these maps potentially contain an enormous
+amount of information about the evolution of structure. Whereas spectral
+information can distinguish the thermal Sunyaev-Zeldovich (tSZ) effect from
+other anisotropies, the spectral form of anisotropies generated by the
+gravitational lensing and the kinetic Sunyaev-Zeldovich (kSZ) effects are
+identical. While spectrally identical, the statistical properties of these
+effects are different. We introduce a new real-space statistic, $<\theta
+(\hat{n})^3 \theta (\hat{m})>_c$, and show that it is identically zero for
+weakly lensed primary anisotropies and, therefore, allows a direct measurement
+of the kSZ effect. Measuring this statistic can offer a new tool for studing
+the reionization epoch. Models with the same optical depth, but different
+reionization histories, can differ by more than a factor of 3 in the amplitude
+of the kSZ-generated non-Gaussian signal.",0610007v2
+2006-12-13,Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies: The Effect of a Cosmological Constant,"We explore the large angular scale temperature anisotropies in the cosmic
+microwave background (CMB) due to homogeneous local dust-filled voids in a flat
+Friedmann-Robertson-Walker universe with a cosmological constant. In comparison
+with the equivalent dust-filled void model in the Einstein-de Sitter
+background, we find that the anisotropy for compensated asymptotically
+expanding local voids can be larger because second-order effects enhance the
+linear integrated Sachs-Wolfe (ISW) effect. However, for local voids that
+expand sufficiently faster than the asymptotic velocity of the wall, the
+second-order effect can suppress the fluctuation due to the linear ISW effect.
+A pair of quasi-linear compensated asymptotic local voids with radius
+(2-3)*10^2 ~h^{-1} Mpc and a matter density contrast ~-0.3 can be observed as
+cold spots with a temperature anisotropy Delta T/T~O(10^{-5}) that might help
+explain the observed large-angle CMB anomalies. We predict that the associated
+anisotropy in the local Hubble constant in the direction of the voids could be
+as large as a few percent.",0612347v2
+2006-12-26,Anisotropy of dark matter annihilation with respect to the Galactic plane,"We describe the anisotropy of dark matter clump distribution caused by tidal
+destruction of clumps in the Galactic disk. A tidal destruction of clumps with
+orbit planes near the disk plane occurs more efficiently as compared with
+destruction of clumps at near-polar orbits. A corresponding annihilation of
+dark matter particles in small-scale clumps produces the anisotropic gamma-ray
+signal with respect to the Galactic disk. This anisotropy is rather small, 9%,
+and superimposed on that due to off-centering position of the Sun in the
+Galaxy. The anisotropy of annihilation signal with respect to the Galactic disk
+provides a possibility to discriminate dark matter annihilation from the
+diffuse gamma-ray backgrounds of other origin.",0612733v2
+1994-11-04,Theoretical Study of Time-Resolved Fluorescence Anisotropy from Coupled Chromophore Pairs,"Calculations of time-resolved fluorescence anisotropy from a pair of
+chromophores coupled by an excitation transfer interaction are presented. For
+the purpose of investigating the effects of nuclear motion on the energy
+transfer and anisotropy, an illustrative model is developed that provides each
+chromophore with a single intramolecular vibrational mode. Account is taken of
+non-instantaneous excitation and time- and frequency-resolved detection.
+Effects of excitation pulse duration, detection window duration and frequency
+resolution, and excitation transfer coupling strength on the time-resolved
+anisotropy are examined in detail. Effects of vibrational relaxation and
+dephasing are also examined using a simplified Redfield description of the
+effects of coupling to a thermal bath.",9411004v1
+1995-07-14,Density of States Driven Anisotropies Induced by Momentum Decoupling in High-Tc Superconductors,"Momentum decoupling arises when small momentum transfer processes dominate
+the electron-phonon scattering and implies that anisotropies in
+superconductivity are driven by the anisotropies of the density of states.
+Considering an isotropic s-wave interaction in the momentum decoupling regime
+we give a natural simultaneous explanation to various aspects of ARPES and
+tunnel experiments on $Bi_2Sr_2CaCu_2O_8$, including the correlation of gap
+magnitude and visibility of the dip above the gap, the enhancement of
+anisotropy with temperature, the presence of gap minima away from the
+$\Gamma-X$ direction and a gap maximum in the $\Gamma-X$ direction, the
+similarity of tunnel and ARPES spectra in the $\Gamma-\bar{M}$ direction and
+the asymmetry in the SIN tunnel spectra where the dip structure is present only
+at negative sample bias.",9507052v1
+1996-07-29,Spin-one ferromagnets with single-ion anisotropy in a perpendicular external field,"In this paper, the conventional Holstein-Primakoff method is generalized with
+the help of the characteristic angle transformation [Lei Zhou and Ruibao Tao,
+J. Phys. A {\bf 27} 5599 (1994)] for the spin-one magnetic systems with
+single-ion anisotropies. We find that the weakness of the conventional method
+for such systems can be overcome by the new approach. Two models will be
+discussed to illuminate the main idea, which are the ``easy-plane"" and the
+``easy-axis"" spin-one ferromagnet, respectively. Comparisons show that the
+current approach can give reasonable ground state properties for the magnetic
+system with ``easy-plane"" anisotropy though the conventional method never can,
+and can give a better representation than the conventional one for the magnetic
+system with ``easy-axis"" anisotropy though the latter is usually believed to be
+a good approximation in such case. Study of the easy-plane model shows that
+there is a phase transition induced by the external field, and the
+low-temperature specific heat may have a peak as the field reaches the critical
+value.",9607207v1
+1997-07-29,Spin-Orbit-Induced Magnetic Anisotropy for Impurities in Metallic Samples II. Finite Size Dependence in the Kondo Resistivity,"The electrical resistivity including the Kondo resistivity increase at low
+temperature is calculated for thin films of dilute magnetic alloys. Assuming
+that in the non-magnetic host the spin-orbit interaction is strong like in Au
+and Cu, the magnetic impurities have a surface anisotropy calculated in part I.
+That anisotropy hinders the motion of the spin. Including that anisotropy the
+effective electron-impurity coupling is calculated by using the second order
+renormalization group equations. The amplitude of the Kondo resistivity
+contribution is reduced as the position of the impurity approaches the surface
+but the increase occurs approximately at the bulk Kondo temperature. Different
+proximity effects observed by Giordano are also explained qualitatively where
+the films of magnetic alloys are covered by pure second films with different
+mean free path. The theory explains the experimental results in those cases
+where a considerable amount of impurities is at the surface inside the
+ballistic region.",9707299v1
+1997-11-12,Phase-transitions induced by easy-plane anisotropy in the classical Heisenberg antiferromagnet on a triangular lattice: a Monte Carlo simulation,"We present the results of Monte Carlo simulations for the antiferromagnetic
+classical XXZ model with easy-plane exchange anisotropy on the triangular
+lattice, which causes frustration of the spin alignment. The behaviour of this
+system is similar to that of the antiferromagnetic XY model on the same
+lattice, showing the signature of a Berezinskii-Kosterlitz-Thouless transition,
+associated to vortex-antivortex unbinding, and of an Ising-like one due to the
+chirality, the latter occurring at a slightly higher temperature. Data for
+internal energy, specific heat, magnetic susceptibility, correlation length,
+and some properties associated with the chirality are reported in a broad
+temperature range, for lattice sizes ranging from 24x24 to 120x120; four values
+of the easy-plane anisotropy are considered. Moving from the strongest towards
+the weakest anisotropy (1%) the thermodynamic quantities tend to the isotropic
+model behaviour, and the two transition temperatures decrease by about 25% and
+22%, respectively.",9711104v2
+1998-01-15,Magnetization switching in a Heisenberg model for small ferromagnetic particles,"We investigate the thermally activated magnetization switching of small
+ferromagnetic particles driven by an external magnetic field. For low uniaxial
+anisotropy the spins can be expected to rotate coherently, while for sufficient
+large anisotropy they should behave Ising-like, i.e., the switching should then
+be due to nucleation. We study this crossover from coherent rotation to
+nucleation for the classical three-dimensional Heisenberg model with a finite
+anisotropy. The crossover is influenced by the size of the particle, the
+strength of the driving magnetic field, and the anisotropy. We discuss the
+relevant energy barriers which have to be overcome during the switching, and
+find theoretical arguments which yield the energetically favorable reversal
+mechanisms for given values of the quantities above. The results are confirmed
+by Monte Carlo simulations of Heisenberg and Ising models.",9801154v2
+1998-05-01,Band structures and optical properties of GaInAs quantum wires grown by strain-induced lateral ordering,"Band structures and optical matrix elements of strained multiple
+quantum-wires (QWR's) are investigated theoretically via the effective
+bond-orbital model, which takes into account the effects of valence-band
+anisotropy and the band mixing. In particular, the Ga$_{1-x}$In$_x$As QWR's
+grown by strain-induced lateral ordering (SILO) are considered. Recently, long
+wavelength Ga$_{1-x}$In$_x$As QWR lasers have been fabricated via a single step
+molecular beam epitaxy technique which uses the SILO process.[1] Low threshold
+current and high optical anisotropy have been achieved. Multi-axial strains
+[combinations of biaxial strains in the (001) and (110) planes] for QWR's are
+considered, Our calculated anisotropy in optical matrix elements (for light
+polarized parallel versus perpendicular to the QWR's axis) is in good agreement
+with experiment. We also find that the strain tends to increase the quantum
+confinement and enhance the anisotropy of the optical transitions.",9805016v1
+1998-05-29,Scaling theory of magnetic ordering in the Kondo lattices with anisotropic exchange interactions,"The lowest-order scaling consideration of the magnetic state formation in the
+Kondo lattices is performed within the $s-f$ model with inclusion of anisotropy
+for both the $f-f$ coupling and $s-f$ exchange interaction. The Kondo
+renormalizations of the effective transverse and longitudinal $s-f$ coupling
+parameters, spin-wave frequency, gap in the magnon spectrum and ordered moment
+are calculated in the case of both ferro- and antiferromagnets. The
+anisotropy-driven change of the scaling behavior (e.g., critical value of $g$
+for entering the strong-coupling region and the corresponding critical
+exponents) is investigated numerically for N=2 and analytically in the large-N
+limit. The dependence of the effective Kondo temperature on the bare $s-f$
+coupling parameter $g$ weakens in the presence of anisotropy. The relative
+anisotropy parameters for both the $s-f$ and $f-f$ coupling are demonstrated to
+decrease during the renormalization process. The role of next-nearest exchange
+interactions for this effect in the antiferromagnet is discussed.",9805390v2
+1998-09-17,Magnetization Switching in Small Ferromagnetic Particles: Nucleation and Coherent Rotation,"The mechanisms of thermally activated magnetization switching in small
+ferromagnetic particles driven by an external magnetic field are investigated.
+For low uniaxial anisotropy the spins rotate coherently while for sufficiently
+large uniaxial anisotropy they behave Ising-like, i.e. the switching then is
+due to nucleation. The crossover from coherent rotation to nucleation is
+studied for the classical three-dimensional Heisenberg model with uniaxial
+anisotropy by Monte Carlo simulations. From the temperature dependence of the
+metastable lifetime the energy barrier of a switching process can be
+determined. For the case of infinite anisotropy we compare numerical results
+from simulations of the Ising model with theoretical results for energy
+barriers for both, single-droplet and multi-droplet nucleation. The simulated
+barriers are in agreement with the theoretical predictions.",9809237v1
+1999-02-11,A Comparative Study of the Magnetization Process of Two-Dimensional Antiferromagnets,"Plateaux in the magnetization curves of the square, triangular and hexagonal
+lattice spin-1/2 XXZ antiferromagnet are investigated. One finds a zero
+magnetization plateau (corresponding to a spin-gap) on the square and hexagonal
+lattice with Ising-like anisotropies, and a plateau with one third of the
+saturation magnetization on the triangular lattice which survives a small
+amount of easy-plane anisotropy. Here we start with transfer matrix
+computations for the Ising limit and continue with series in the XXZ-anisotropy
+for plateau-boundaries using the groundstates of the Ising limit. The main
+focus is then a numerical computation of the magnetization curves with
+anisotropies in the vicinity of the isotropic situation. Finally, we discuss
+the universality class associated to the asymptotic behaviour of the
+magnetization curve close to saturation, as observed numerically in two and
+higher dimensions.",9902163v1
+1999-02-16,Dependence of Magnetic Anisotropy and Magnetoresistance of Ni81Fe19-Films on Annealing,"Permalloy (Py:Ni81Fe19) exhibits an anisotropic magnetoresistance (AMR) which
+is very often used to read magnetic signals from storage devices. Py-films of
+thickness 20nm were prepared by dc-magnetron sputtering in a magnetic field
+onto thermally oxidized Si-wafers and annealed ex situ at temperatures up to
+1000K in order to investigate the dependence of the magnetic anisotropy and the
+AMR on heat treatments. The films exhibit an uniaxial anisotropy after
+preparation which changes during annealing above 520K. The AMR along the former
+magnetically easy axis as well as the corresponding field sensitivity are
+increased by a heat treatment around 700K reaching maxima of about 8% and a
+maximum sensitivity of 1.5%/Oe, respectively. We discuss possible sources for
+the change in anisotropy, i.e. strain effects, inhomogeneities, and changes of
+the local atomic order.",9902222v1
+1999-05-12,Effects of dimensionality and anisotropy on the Holstein polaron,"We apply weak-coupling perturbation theory and strong-coupling perturbation
+theory to the Holstein molecular crystal model in order to elucidate the
+effects of anisotropy on polaron properties in D dimensions. The ground state
+energy is considered as a primary criterion through which to study the effects
+of anisotropy on the self-trapping transition, the self-trapping line
+associated with this transition, and the adiabatic critical point. The effects
+of dimensionality and anisotropy on electron-phonon correlations and polaronic
+mass enhancement are studied, with particular attention given to the polaron
+radius and the characteristics of quasi-1D and quasi-2D structures.
+Perturbative results are confirmed by selected comparisons with variational
+calculations and quantum Monte Carlo data.",9905148v2
+1999-05-31,Magnetoelastic mechanism of spin-reorientation transitions at step-edges,"The symmetry-induced magnetic anisotropy due to monoatomic steps at strained
+Ni films is determined using results of first - principles relativistic
+full-potential linearized augmented plane wave (FLAPW) calculations and an
+analogy with the N\'eel model. We show that there is a magnetoelastic
+anisotropy contribution to the uniaxial magnetic anisotropy energy in the
+vicinal plane of a stepped surface. In addition to the known spin-direction
+reorientation transition at a flat Ni/Cu(001) surface, we propose a
+spin-direction reorientation transition in the vicinal plane for a stepped
+Ni/Cu surface due to the magnetoelastic anisotropy. We show that with an
+increase of Ni film thickness, the magnetization in the vicinal plane turns
+perpendicular to the step edge at a critical thickness calculated to be in the
+range of 16-24 Ni layers for the Ni/Cu(1,1,13) stepped surface.",9905437v1
+1999-10-18,Field-induced magnetic reorientation and effective anisotropy of a ferromagnetic monolayer within spin wave theory,"The reorientation of the magnetization of a ferromagnetic monolayer is
+calculated with the help of many-body Green's function theory. This allows, in
+contrast to other spin wave theories, a satisfactory calculation of magnetic
+properties over the entire temperature range of interest since interactions
+between spin waves are taken into account. A Heisenberg Hamiltonian plus a
+second-order uniaxial single-ion anisotropy and an external magnetic field is
+treated by the Tyablikov (Random Phase Approximation: RPA) decoupling of the
+exchange interaction term and the Anderson-Callen decoupling of the anisotropy
+term. The orientation of the magnetization is determined by the spin components
+$\la S^\alpha\ra$ ($\alpha=x,y,z$), which are calculated with the help of the
+spectral theorem. The knowledge of the orientation angle $\Theta_0$ allows a
+non-perturbative determination of the temperature dependence of the effective
+second-order anisotropy coefficient. Results for the Green's function theory
+are compared with those obtained with mean-field theory (MFT). We find
+significant differences between these approaches.",9910280v1
+1999-11-19,Superconducting properties of Y_xLu_(1-x)Ni2B2C and La3Ni2B2N3: A comparison between experiment and Eliashberg theory,"Specific heat and resistivity measurements were performed on polycrystalline
+samples of the solid-solution Y_xLu_(1-x)Ni2B2C in order to determine
+thermodynamic properties such as the specific-heat difference, the
+thermodynamic critical field H_c(T), as well as the upper critical field
+H_{c2}(T). These properties were analyzed within the Eliashberg theory
+including anisotropy effects, yielding electron-phonon coupling anisotropy
+parameters <a_k^2> ranging beween 0.02 and 0.03 for the whole series, and Fermi
+velocity anisotropy parameters of <b_k^2> = 0.245-0.3. Excellent agreement
+between theory and experiment was achieved for these parameters, the Sommerfeld
+constant and model phonon spectra determined from specific heat measurements.
+An analysis of the previously investigated boronitride La3Ni2B2N3 for
+comparison revealed the electron-phonon anisotropy to be of great significance
+in describing its thermodynamic properties and the calculations yielded <a_k^2>
+\~ 0.08 and <b_k^2> ~ 0.245. The T_c-behavior within the series
+Y_xLu_(1-x)Ni2B2C is discussed in terms of coupling and impurity effects, and
+the density of states at the Fermi level N(0).",9911305v2
+1999-12-02,Generalized Phase Field Model for Computer Simulation of Grain Growth in Anisotropic Systems,"We study the dynamics and morphology of grain growth with anisotropic energy
+and mobility of grain boundaries using a generalized phase field model. In
+contrast to previous studies, both inclination and misorientation of the
+boundaries are considered. The model is first validated against exact
+analytical solutions for the classical problem of an island grain embedded in
+an infinite matrix. It is found that grain boundary energy anisotropy has a
+much stronger effect on grain shape than that of mobility anisotropy. In a
+polycrystalline system with mobility anisotropy, we find that the system
+evolves in a non-self-similar manner and grain shape anisotropy develops.
+However, the average area of the grains grows linearly with time, as in an
+isotropic system.",9912044v1
+1999-12-21,Schwinger boson theory of anisotropic ferromagnetic ultrathin films,"Ferromagnetic thin films with magnetic single-ion anisotropies are studied
+within the framework of Schwinger bosonization of a quantum Heisenberg model.
+Two alternative bosonizations are discussed. We show that qualitatively correct
+results are obtained even at the mean-field level of the theory, similar to
+Schwinger boson results for other magnetic systems. In particular, the
+Mermin-Wagner theorem is satisfied: a spontaneous magnetization at finite
+temperatures is not found if the ground state of the anisotropic system
+exhibits a continuous degeneracy. We calculate the magnetization and effective
+anisotropies as functions of exchange interaction, magnetic anisotropies,
+external magnetic field, and temperature for arbitrary values of the spin
+quantum number. Magnetic reorientation transitions and effective anisotropies
+are discussed. The results obtained by Schwinger boson mean-field theory are
+compared with the many-body Green's function technique.",9912382v2
+2000-08-17,Vortex Lines or Vortex-Line Chains at the Lower Critical Field in Anisotropic Superconductors?,"The vortex state at the lower critical field, H_{c1}, in clean anisotropic
+superconductors placed in an external field tilted with respect to the axis of
+anisotropy (c-axis) is considered assuming two possible arrangements: dilute
+vortex-lines or dilute vortex-line chains. By minimizing the Gibbs free
+energies in the London limit for each possibility we obtain the corresponding
+lower critical fields as a function of the tilt angle. The equilibrium
+configuration at H_{c1} for a given tilt angle is identified with that for
+which H_{c1} is the smallest. We report results for parameter values typical of
+strong and moderate anisotropy. We find that for strong anisotropy vortex-line
+chains are favored for small tilt angles (< 7.9^o) and that at 7.9^o there is
+coexistence between this configuration and a vortex-line one. For moderate
+anisotropy we find that there is little difference between the vortex-line and
+the vortex-chain lower critical fields.",0008261v1
+2000-08-23,Weak ferromagnetism and field-induced spin reorientation in K2V3O8,"Magnetization and neutron diffraction measurements indicate long-range
+antiferromagnetic ordering below TN=4 K in the 2D, S=1/2 Heisenberg
+antiferromagnet K2V3O8. The ordered state exhibits ``weak ferromagnetism'' and
+novel, field-induced spin reorientations. These experimental observations are
+well described by a classical, two-spin Heisenberg model incorporating
+Dzyaloshinskii-Moriya interactions and an additional c-axis anisotropy. This
+additional anisotropy can be accounted for by inclusion of the symmetric
+anisotropy term recently described by Kaplan, Shekhtman, Entin-Wohlman, and
+Aharony. This suggests that K2V3O8 may be a very unique system where the
+qualitative behavior relies on the presence of this symmetric anisotropy.",0008351v1
+2001-01-17,Phenomenological theory of magnetic anisotropy in thin films and multilayers,"Within a phenomenological approach the density of induced uniaxial anisotropy
+in nanostructures K(r) is treated as a physical field additional to the
+magnetization M(r). The equilibrium distributions of K(r) are formed under the
+influence of the surfaces and internal interactions. The functions K(r) and
+M(r) are calculated for a magnetic layer between two nonmagnetic spacers. It is
+shown that the transition from the phase with magnetization in plane to the
+perpendicular phase occurs continuously via an intermediate phase which is
+inhomogeneous across the layer-thickness. The theory explains experimentally
+observed thickness dependences of the effective anisotropy and gives a method
+to obtain values of the characteristic parameters for the theory from
+experimental data. It is shown that the separation of the induced anisotropy
+into volume and surface contribution is valid only for thick films.",0101262v1
+2001-02-12,Lattice anisotropy as microscopic origin of static stripes in cuprates,"Structural distortions in cuprate materials offer a microscopic origin for
+anisotropies in electron transport in the basal plane. Using a real-space
+Hartree-Fock approach, we consider the ground states of the anisotropic Hubbard
+(t_x \ne t_y) and t-J (t_x \ne t_y, J_x \ne J_y) models. Symmetrical but
+inhomogeneous (``polaronic'') charge structures in the isotropic models are
+altered even by rather small anisotropies to one-dimensional, stripe-like
+features. We find two distinct types of stripe, namely uniformly filled,
+antiphase domain walls and non-uniform, half-filled, in-phase ones. We
+characterize their properties, energies and dependence on the model parameters,
+including filling and anisotropy in t (and J). We discuss the connections among
+these results, other theoretical studies and experimental observation.",0102201v1
+2001-06-08,Reduced symmetry of heterointerfaces and orientational pinning of quantum Hall stripe phase,"In a 2D electron system in (001) GaAs/AlGaAs upon filling high Landau levels,
+it was recently observed a new class of collective states, which are recognized
+now to relate to the spontaneous formation of a charge density wave (``stripe
+phase''). Here we analyze one of the possible mechanisms of the stripe pinning
+along the crystallographic direction [110]--the native effective mass
+anisotropy of 2D electrons. It is shown that for a symmetric quantum well this
+anisotropy is a linear function of applied perpendicular-to-plane electric
+field. So, if it is the anisotropy that defines the direction of the stripes,
+the critical in-plane magnetic field, when the stripes rotate, will strongly
+depend on the bias. The proper experiment will answer the question whether the
+native anisotropy of the effective mass is the mechanism of the pinning.",0106162v1
+2001-08-03,Electrical Resistivity Anisotropy from Self-Organized One-Dimensionality in High-Temperature Superconductors,"We investigate the manifestation of the stripes in the in-plane resistivity
+anisotropy in untwinned single crystals of La_{2-x}Sr_{x}CuO_{4} (x = 0.02 -
+0.04) and YBa_{2}Cu_{3}O_{y} (y = 6.35 - 7.0). It is found that both systems
+show strongly temperature-dependent in-plane anisotropy in the lightly
+hole-doped region and that the anisotropy in YBa_{2}Cu_{3}O_{y} grows with
+decreasing y below about 6.60 despite the decreasing orthorhombicity, which
+gives most direct evidence that electrons self-organize into a macroscopically
+anisotropic state. The transport is found to be easier along the direction of
+the spin stripes already reported, demonstrating that the stripes are
+intrinsically conducting in cuprates.",0108053v2
+2001-11-07,Critical behavior of the two-dimensional N-component Landau-Ginzburg Hamiltonian with cubic anisotropy,"We study the two-dimensional N-component Landau-Ginzburg Hamiltonian with
+cubic anisotropy. We compute and analyze the fixed-dimension perturbative
+expansion of the renormalization-group functions to four loops. The relations
+of these models with N-color Ashkin-Teller models, discrete cubic models,
+planar model with fourth order anisotropy, and structural phase transition in
+adsorbed monolayers are discussed. Our results for N=2 (XY model with cubic
+anisotropy) are compatible with the existence of a line of fixed points joining
+the Ising and the O(2) fixed points. Along this line the exponent $\eta$ has
+the constant value 1/4, while the exponent $\nu$ runs in a continuous and
+monotonic way from 1 to $\infty$ (from Ising to O(2)). For N\geq 3 we find a
+cubic fixed point in the region $u, v \geq 0$, which is marginally stable or
+unstable according to the sign of the perturbation. For the physical relevant
+case of N=3 we find the exponents $\eta=0.17(8)$ and $\nu=1.3(3)$ at the cubic
+transition.",0111118v2
+2001-12-10,Temperature and field dependence of the anisotropy of MgB2,"The anisotropy gamma of the superconducting state of high quality
+single-crystals of MgB2 was determined, using torque magnetometry with two
+different methods. The anisotropy of the upper critical field was found to be
+temperature dependent, decreasing from gamma = 6 at 15 K to 2.8 at 35 K.
+Reversible torque data near Tc reveal a field dependent anisotropy, increasing
+nearly linearly from gamma = 2 in zero field to 3.7 in 10 kOe. The unusual
+temperature dependence is a true bulk property and can be explained by
+non-local effects of anisotropic pairing and/or the wave vector dependence of
+the effective mass tensor.",0112166v3
+2002-01-02,Anisotropies of the Hamiltonian and the Wave Function: Inversion Phenomena in Quantum Spin Chains,"We investigate the inversion phenomenon between the XXZ anisotropies of the
+Hamiltonian and the wave function in quantum spin chains, mainly focusing on
+the S=1/2 trimerized XXZ model with the next-nearest-neighbor interactions. We
+have obtained the ground-state phase diagram by use of the degenerate
+perturbation theory and the level spectroscopy analysis of the numerical data
+calculated by the Lanczos method. In some parameter regions, the spin-fluid is
+realized for the Ising-like anisotropy, and the Neel state for the XY-like
+anisotropy, against the ordinary situation.",0201014v1
+2002-04-11,In-plane Anisotropy on Resistivity and Thermopower in The Misfit Layered Oxide Bi2-xPbxSr2Co2Oy,"We investigated the in-plane anisotropy on the resistivity and thermopower of
+Bi2-xPbxSr2Co2Oy single crystals, which have a misfit structure between the
+hexagonal CoO2 layer and the rock salt Bi2Sr2O4 layer. The resistivity and
+thermopower show significantly large anisotropy, which exceeds two at maximum.
+This anisotropy would come from the anisotropic pseudogap formation enhanced by
+the misfit structure. The thermopower changes with Pb doping to take a maximum
+at x=0.4. The misfit structure improves the thermoelectric properties through
+chemical pressure. The power factor is as large as 9 muW/cmK2 at 100 K for
+x=0.6, which is the highest value for thermoelectric oxides at 100 K.",0204245v1
+2002-06-11,Dynamics of Low Anisotropy Morphologies in Directional Solidification,"We report experimental results on quasi-two-dimensional diffusion limited
+growth in directionally solidified succinonitrile with small amounts of
+poly(ethylene oxide), acetone, or camphor as a solute. Seaweed growth, or dense
+branching morphology, is selected by growing grains close to the $\{111\}$
+plane, where the in-plane surface tension is nearly isotropic. The observed
+growth morphologies are very sensitive to small anisotropies in surface tension
+caused by misorientations from the $\{111\}$ plane. Different seaweed
+morphologies are found, including the degenerate, the stabilized, and the
+strongly tilted seaweeds. The degenerate seaweeds show a limited fractal
+scaling range and, with increased undercooling, suggests a transition from
+""fractal"" to ""compact"" seaweed. Strongly tilted seaweeds demonstrate a
+significant twofold anisotropy. In addition, seaweed-dendrite transitions are
+observed in low anisotropy growth.",0206179v1
+2002-06-21,"Comment on ""Superconducting anisotropy and evidence for intrinsic pinning in single crystalline MgB2""","In a recent paper [Phys. Rev. B 66, 012501 (2002)], torque data measured on a
+MgB2 single crystal in fields from 10 to 60 kOe at 10 K were presented. The
+authors obtained the anisotropy gamma by fitting a theoretical expression to
+the data and concluded that the anisotropy is field independent gamma \approx
+4.3. They also reported the observation of ""intrinsic pinning"", which they take
+as experimental evidence for the occurence of superconductivity in the boron
+layers. In this comment, we discuss the range of validity of the theoretical
+expression used by the authors and show that the conclusion of a field
+independent anisotropy does not hold. Furthermore, we present torque data
+measured on two crystals of MgB2, establishing the extrinsic nature of the peak
+in the irreversible torque observed in some crystals.",0206407v1
+2002-07-25,Ground State Phase Diagram of the Distorted S=1 Kagomé Heisenberg Antiferromagnets with Single-site Anisotropy,"The ground state phase transitions in the distorted S=1 kagome Heisenberg
+antiferromagnet (KHAF) with single-site anisotropy D are studied by the
+numerical exact diagonalization method. For strong easy plane anisotropy, the
+hexgonal singlet solid (HSS) ground state of the uniform KHAF is destroyed and
+large-D state is realized. The quantum phase transition between these two
+states is analogous to the Haldane-large-D transition in the S=1
+antiferromagnetic Heisenberg chain. The combined effect of the sqrt(3) times
+sqrt(3) lattice distortion and single site anisotropy is also investigated. The
+ground state phase diagram expected from the numerical results is presented.
+The presence of this transition is consistent with the HSS picture of the
+ground state of the uniform S=1 KHAF and supports its validity.",0207595v1
+2002-08-12,"Fe/V and Fe/Co (001) superlattices: growth, anisotropy, magnetisation and magnetoresistance","Some physical properties of bcc Fe/V and Fe/Co (001) superlattices are
+reviewed. The dependence of the magnetic anisotropy on the in-plane strain
+introduced by the lattice mismatch between Fe and V is measured and compared to
+a theoretical derivation. The dependence of the magnetic anisotropy (and
+saturation magnetisation) on the layer thickness ratio Fe/Co is measured and a
+value for the anisotropy of bcc Co is derived from extrapolation. The
+interlayer exchange coupling of Fe/V superlattices is studied as a function of
+the layer thickness V (constant Fe thickness) and layer thickness of Fe
+(constant V thickness). A region of antiferromagnetic coupling and GMR is found
+for V thicknesses 12-14 monolayers. However, surprisingly, a 'cutoff' of the
+antiferromagnetic coupling and GMR is found when the iron layer thickness
+exceeds about 10 monolayers.",0208229v1
+2002-10-08,Microwave Surface Resistance and Upper-Critical-Field Anisotropy of MgB2 Superconductor,"The field-induced variations of the microwave surface resistance are
+investigated in two different samples of powdered MgB2. The experimental
+results can be justified in the framework of the Coffey and Clem model with
+fluxons moving in the flux-flow regime, provided that the anisotropy of the
+upper critical field is taken into due account. Assuming the angular dependence
+of the upper critical field expected from the anisotropic Ginzburg-Landau
+theory, we determine the anisotropy factor by fitting the experimental data of
+the field dependence of the microwave surface resistance. We show that the
+anisotropy factor is constant in a range of temperatures of about 3 K below Tc
+and it takes on different values for the two samples, even though they have
+similar shape.",0210178v1
+2002-10-31,Anisotropy of the superconducting state properties and phase diagram of MgB2 by torque magnetometry on single crystals,"The angular and temperature dependence of the upper critical field Hc2 in
+MgB2 was determined from torque magnetometry measurements on single crystals.
+The Hc2 anisotropy gamma_H was found to decrease with increasing temperature,
+in disagreement with the anisotropic Ginzburg-Landau theory, which predicts
+that the gamma_H is temperature independent. This behaviour can be explained by
+the two band nature of superconductivity in MgB2. An analysis of measurements
+of the reversible torque in the mixed state yields a field dependent effective
+anisotropy gamma_eff, which can be at least partially explained by different
+anisotropies of the penetration depth and the upper critical field. It is shown
+that a peak effect in fields of about 0.85 Hc2 is a manifestation of an
+order-disorder phase transition of vortex matter. The H-T phase diagram of MgB2
+for H//c correlates with the intermediate strength of thermal fluctuations in
+MgB2, as compared to those in high and low Tc superconductors.",0210701v1
+2003-02-26,In-plane magnetic reorientation in coupled ferro- and antiferromagnetic thin films,"By studying coupled ferro- (FM) and antiferromagnetic (AFM) thin film
+systems, we obtain an in-plane magnetic reorientation as a function of
+temperature and FM film thickness. The interlayer exchange coupling causes a
+uniaxial anisotropy, which may compete with the intrinsic anisotropy of the FM
+film. Depending on the latter the total in-plane anisotropy of the FM film is
+either enhanced or reduced. Eventually a change of sign occurs, resulting in an
+in-plane magnetic reorientation between a collinear and an orthogonal magnetic
+arrangement of the two subsystems. A canted magnetic arrangement may occur,
+mediating between these two extremes. By measuring the anisotropy below and
+above the N\'eel temperature the interlayer exchange coupling can be
+determined. The calculations have been performed with a Heisenberg-like
+Hamiltonian by application of a two-spin mean-field theory.",0302535v1
+2003-03-18,Calculation of magnetic anisotropy energy in SmCo5,"SmCo5 is an important hard magnetic material, due to its large magnetic
+anisotropy energy (MAE). We have studied the magnetic properties of SmCo5 using
+density functional theory (DFT) calculations where the Sm f-bands, which are
+difficult to include in DFT calculations, have been treated within the LDA+U
+formalism. The large MAE comes mostly from the Sm f-shell anisotropy, stemming
+from an interplay between the crystal field and the spin-orbit coupling. We
+found that both are of similar strengths, unlike some other Sm compounds,
+leading to a partial quenching of the orbital moment (f-states cannot be
+described as either pure lattice harmonics or pure complex harmonics), an
+optimal situation for enhanced MAE. A smaller portion of the MAE can be
+associated with the Co-d band anisotropy, related to the peak in the density of
+states at the Fermi energy. Our result for the MAE of SmCo5, 21.6 meV/f.u.,
+agrees reasonably with the experimental value of 13-16 meV/f.u., and the
+calculated magnetic moment (including the orbital component) of 9.4 mu_B agrees
+with the experimental value of 8.9 mu_B.",0303368v1
+2003-04-09,Field-induced magnetic anisotropy in La0.7Sr0.3CoO3,"Magnetic anisotropy has been measured for the ferromagnetic La0.7Sr0.3CoO3
+perovskite from an analysis of the high-field part of the magnetization vs.
+field curves, i.e., the magnetic saturation regime. These measurements give a
+magnetic anistropy one order of magnitude higher than that of reference
+manganites. Surprisingly, the values of the magnetic anisotropy calculated in
+this way do not coincide with those estimated from measurements of coercive
+fields which are one order of magnitude smaller. It is proposed that the reason
+of this anomalous behaviour is a transition of the trivalent Co ions under the
+external magnetic field from a low-spin to an intermediate-spin state. Such a
+transition converts the Co3+ ions into Jahn-Teller ions having an only
+partially quenched orbital angular momentum, which enhances the intra-atomic
+spin-orbit coupling and magnetic anisotropy.",0304211v1
+2003-05-05,Spin Anisotropy and Slow Dynamics in Spin Glasses,"We report on an extensive study of the influence of spin anisotropy on spin
+glass aging dynamics. New temperature cycle experiments allow us to compare
+quantitatively the memory effect in four Heisenberg spin glasses with various
+degrees of random anisotropy and one Ising spin glass. The sharpness of the
+memory effect appears to decrease continuously with the spin anisotropy.
+Besides, the spin glass coherence length is determined by magnetic field change
+experiments for the first time in the Ising sample. For three representative
+samples, from Heisenberg to Ising spin glasses, we can consistently account for
+both sets of experiments (temperature cycle and magnetic field change) using a
+single expression for the growth of the coherence length with time.",0305088v2
+2003-06-13,Modification of the classical Heisenberg helimagnet by weak uniaxial anisotropy and magnetic field,"Classical ground state of the isotropic Heisenberg spin Hamiltonian on a
+primitive Bravais lattice is known to be a single-Q planar spin spiral. A
+uniaxial anisotropy and external magnetic field distort this structure by
+generating the higher-order Fourier harmonics at wave-vectors nQ in the spatial
+spin configuration. These features are not captured in the formalism based on
+the Luttinger-Tisza theorem, where the classical ground state energy is
+minimized under the ``weak'' condition on the length of the spins. We discuss
+why the correct solution is lost in that approach and present an alternative
+microscopic treatment of the problem. It allows to find the classical ground
+state for general Q for both easy-axis and easy-plane uniaxial second-order
+anisotropy, and for any orientation of the magnetic field, by treating the
+effect of anisotropy (but not the field) as a perturbation to the exchange
+structure. As a result, the classical ground state energy, the uniform
+magnetization, and the magnetic Bragg peak intensities that are measured in
+experiment, are calculated.",0306370v1
+2003-06-19,Exchange anisotropy and the dynamic phase transition in thin ferromagnetic Heisenberg films,"Monte Carlo simulations have been performed to investigate the dependence of
+the dynamic phase behavior on the bilinear exchange anisotropy of a classical
+Heisenberg spin system. The system under consideration is a planar thin
+ferromagnetic film with competing surface fields subject to a pulsed
+oscillatory external field. The results show that the films exhibit a single
+discontinuous dynamic phase transition (DPT) as a function of the anisotropy of
+the bilinear exchange interaction in the Hamiltonian. Furthermore there is no
+evidence of stochastic resonance (SR) associated with the DPT. These results
+are in marked contrast to the continuous DPT observed in the same system as a
+function of temperature and applied field strength for a fixed bilinear
+exchange anisotropy.",0306502v1
+2003-07-17,Vortex-vacancy interactions in two-dimensional easy-plane magnets,"For a model with isotropic nearest neighbor exchange combined with easy-plane
+exchange or single-ion anisotropies, the static effects of a magnetic vacancy
+site on a nearby magnetic vortex are analyzed on square, hexagonal and
+triangular lattices. Numerical energy minimization and linear stability
+analysis using the vortex instability mode are employed. When the vortex is
+centered on a vacancy, the critical anisotropies where the stable vortex
+structure switches from out-of-plane to planar form are determined, and the
+vortex energies and magnetizations are found as functions of anisotropy.
+Consistent with square lattice calculations by Zaspel et al, the strength of
+anisotropy needed to stabilize a vortex in the planar form is reduced when the
+vortex is centered on a vacancy, for all three lattices studied. The
+vortex-on-vacancy energy is found to be smaller than the typical energy of a
+vortex centered between lattice sites in a system without vacancies. For a
+vortex separated from a vacancy, the energy found as a function of separation
+demonstrates an attractive potential between the two.",0307448v1
+2003-08-14,In-Plane Magnetic Anisotropy In RF Sputtered Fe-N Thin Films,"We have fabricated Fe(N) thin films with varied N2 partial pressure and
+studied the microstructure, morphology, magnetic properties and resistivity by
+using X-ray diffraction, atomic force microscopy, transmission electron
+microscopy, vibrating-sample magnetometer and angle-resolved M-H hysteresis
+Loop tracer and standard four-point probe method. In the presence of low N2
+partial pressure, Fe(N) films showed a basic bcc a-Fe structure with a
+preferred (110) texture. A variation of in-plane magnetic anisotropy of the
+Fe(N) films was observed with the changing of N component. The evolution of
+in-plane anisotropy in the films was attributed to the directional order
+mechanism. Nitrogen atoms play an important role in refining the a-Fe grains
+and inducing uniaxial anisotropy.",0308274v1
+2003-08-31,Josephson vortices and solitons inside pancake vortex lattice in layered superconductors,"In very anisotropic layered superconductors a tilted magnetic field generates
+crossing vortex lattices of pancake and Josephson vortices (JVs). We study the
+properties of an isolated JV in the lattice of pancake vortices. JV induces
+deformations in the pancake vortex crystal, which, in turn, substantially
+modify the JV structure. The phase field of the JV is composed of two types of
+phase deformations: the regular phase and vortex phase. The phase deformations
+with smaller stiffness dominate. The contribution from the vortex phase
+smoothly takes over with increasing magnetic field. We find that the structure
+of the cores experiences a smooth yet qualitative evolution with decrease of
+the anisotropy. At large anisotropies pancakes have only small deformations
+with respect to position of the ideal crystal while at smaller anisotropies the
+pancake stacks in the central row smoothly transfer between the neighboring
+lattice positions forming a solitonlike structure. We also find that even at
+high anisotropies pancake vortices strongly pin JVs and strongly increase their
+viscous friction.",0309021v1
+2003-09-04,Orbital-dependent two-band superconductivity in MgB2,"We show that a two-band model with ${\bf k}$-dependent superconducting gaps
+well describes the transmission and optical conductivity measured for MgB$_2$
+thin films. It is also shown that the two-band anisotropic model consistently
+describes the specific-heat jump and thermodynamic critical magnetic field
+$H_c$. A single-gap anisotropic model is shown to be insufficient to understand
+consistently optical and thermodynamic behaviors. In our model, the pairing
+symmetry in each band has an anisotropic characteristic which is determined
+almost uniquely; the superconducting gap in the $\sigma$-band has anisotropy in
+the ab-plane and the gap in the $\pi$-band has a prolate form exhibiting
+anisotropy in the c-direction. The anisotropy in the $\sigma$-band produces
+rather small effects on the physical properties compared to the anisotropy in
+the $\pi$-band.",0309095v1
+2003-10-08,The Role of Nonlocality in the Pinning Properties of Borocarbides Materials,"An experimental review on the influence of nonlocal electrodynamics in the
+vortex pinning properties of non-magnetic borocarbide superconductors is
+presented. We show that the pinning force density Fp exhibits a rich and
+complex anisotropic behavior that sharply contrast with the small mass
+anisotropy of these compounds. For magnetic fields H applied parallel to the
+crystallographic c-axis, the first order reorientation transition between two
+rhombic lattices manifests itself as a kink in Fp(H). For H perpendicular to
+the c-axis, a much larger Fp(H) and a slower relaxation rate is observed. In
+this field configuration, nonlocality induces a fourfold periodicity in Fp when
+H is rotated within the square basal plane. Unlike the out-of-plane anisotropy,
+which persists for increasing impurity levels, the in-plane fourfold anisotropy
+can be strongly suppressed by reducing the electronic mean free path. This
+result unambiguously demonstrate that the in-plane anisotropy is a consequence
+of nonlocal effects.",0310188v2
+2003-10-31,Instability of planar vortices in two-dimensional easy-plane Heisenberg model with distance-dependent interactions,"It is known that magnetic vortices in two dimensional Heisenberg models with
+easy-plane anisotropy exhibit an instability depending on the anisotropy
+strength. In this paper, we study the statistic behavior of the two-dimensional
+easy-plane Heisenberg models with distance-dependent interactions, $J_{xy}(r)$
+and $J_z(r)$ for in-plane and out-of-plane components. We develop analytical
+and numerical methods for accurate determination of critical anisotropy, above
+which out-of-plane vortices are stable. In particular, we explore the vortex
+formation of the Gaussian-type interaction model and determine the critical
+anisotropy accurately for square, hexagonal and triangular lattices.",0310753v2
+2003-12-18,Anisotropy of the orbital methods and the magnetic dipole term $T_z$ in ${\rm CrO_2}$: An {\it ab-initio} studt,"A systematic study is performed by the {\it ab-initio} density functional
+theory of the anisotropy of the orbital moments $<l_z>$ and the magnetic dipole
+term $<T_z>$ in bulk ${\rm CrO_2}$. Two different band-structure techniques are
+used (FLAPW and LMTO-ASA), and the electronic correlations are treated by the
+local-spin-density approximation (LSDA), the LSDA+ orbital polarization method,
+and the LSDA+$U$ method. The calculated anisotropies of $<l_z>$ and $<T_z>$ are
+very large compared to Fe, Ni and Co but still a factor of 5 and 2 smaller than
+the anisotropies obtained from a recently suggested analysis of the X-ray
+magnetic circular dichroism spectra for a thick layer of ${\rm CrO_2}$.",0312468v1
+2004-04-16,Symmetry of Magnetic Quantum Tunneling in the Single-Molecule Magnet Mn12-Acetate,"The symmetry of magnetic quantum tunneling (MQT) in the single molecule
+magnet Mn12-acetate has been determined by sensitive low-temperature magnetic
+measurements in the pure quantum tunneling regime and high frequency EPR
+spectroscopy in the presence of large transverse magnetic fields. The combined
+data set definitely establishes the transverse anisotropy terms responsible for
+the low temperature quantum dynamics. MQT is due to a disorder induced locally
+varying quadratic transverse anisotropy associated with rhombic distortions in
+the molecular environment (2nd order in the spin-operators). This is
+superimposed on a 4th order transverse magnetic anisotropy consistent with the
+global (average) S4 molecule site symmetry. The hard axes associated with these
+forms of the transverse anisotropy are not collinear, leading to a complex
+interplay between local and global symmetries, the consequences of which are
+analyzed in detail.",0404390v2
+2004-05-20,Anisotropy and internal field distribution of MgB2 in the mixed state at low temperatures,"Magnetization and muon spin relaxation on MgB2 were measured as a function of
+field at 2 K. Both indicate an inverse-squared penetration depth strongly
+decreasing with increasing field H below about 1 T. Magnetization also suggests
+the anisotropy of the penetration depth to increase with increasing H,
+interpolating between a low Hc1 and a high Hc2 anisotropy. Torque vs angle
+measurements are in agreement with this finding, while also ruling out drastic
+differences between the mixed state anisotropies of the two basic length scales
+penetration depth and coherence length.",0405495v1
+2004-06-30,Helical anisotropy and magnetoimpedance of CoFeSiB wires under torsional stress,"Recent measurements of the magnetoimpedance (at a fixed frequency of 1 MHz)
+of cobalt-rich wires subjected to torsion stress show an asymmetry as a
+function of torsion angle stemming from residual anisotropies induced during
+wire fabrication. We interpret these measurements with a simple model based on
+the competition between a circumferential magnetic anisotropy and another one
+induced by torsional and residual stress. This allows extraction of the
+physical parameters of the wire and explains the positive and negative torsion
+cases. The agreement between theoretical and experimental results provides a
+firm support for the model describing the behaviour of the anisotropy field
+versus static magnetic field for all torsion angles.",0406767v2
+2004-07-14,Ferromagnetic resonance study of free hole contribution to magnetization and magnetic anisotropy in modulation-doped Ga$_{1 - x}$Mn$_{x}$As/Ga$_{1 - y}$Al$_{y}$As:Be,"Ferromagnetic resonance (FMR) is used to study magnetic anisotropy of GaMnAs
+in a series of Ga$_{1 - x}$Mn$_{x}$As/Ga$_{1 - y}$Al$_{y}$As heterostructures
+modulation-doped by Be. The FMR experiments provide a direct measure of cubic
+and uniaxial magnetic anisotropy fields, and their dependence on the doping
+level. It is found that the increase in doping -- in addition to rising the
+Curie temperature of the Ga$_{1 - x}$Mn$_{x}$As layers -- also leads to a very
+significant increase of their uniaxial anisotropy field. The FMR measurements
+further show that the effective $g$-factor of Ga$_{1 - x}$Mn$_{x}$As is also
+strongly affected by the doping. This in turn provides a direct measure of the
+contribution from the free hole magnetization to the magnetization of Ga$_{1 -
+x}$Mn$_{x}$As system as a whole.",0407371v1
+2004-07-19,Fermi-liquid based theory for the in-plane magnetic anisotropy in untwinned high-T$_c$ superconductors,"Using a generalized RPA-type theory we calculate the in-plane anisotropy of
+the magnetic excitations in hole-doped high-$T_c$ superconductors. Extending
+our earlier Fermi-liquid based studies on the resonance peak by inclusion of
+orthorhombicity we still find two-dimensional spin excitations, however, being
+strongly anisotropic. This reflects the underlying anisotropy of the hopping
+matrix elements and of the resultant superconducting gap function. We compare
+our calculations with new experimental data on {\it fully untwinned}
+${YBa}_2{Cu}_3{O}_{6.85}$ and find good agreement. Our results are in contrast
+to earlier interpretations on the in-plane anisotropy in terms of stripes (H.
+Mook {\it et al.}, Nature {\bf 404}, 729 (2000)), but reveal a conventional
+solution to this important problem.",0407487v2
+2004-10-05,Micellar shape anisotropy and elastic constants in discotic lyotropic liquid crystals,"The elastic constants of a discotic lyotropic nematic liquid crystal are
+calculated by means of a pseudo-molecular approach as functions of the micellar
+shape anisotropy. By assuming that the temperature dependence of the ratio of
+the elastic constants comes from the temperature dependence of the micellar
+shape anisotropy, the theoretical predictions are connected with experimental
+measurements for the ratio $K_{33}/K_{11}$. This procedure permits to
+determine, in a phenomenological way, the temperature dependence for the ratio
+of elastic constants and for the micellar shape anisotropy near the
+nematic-isotropic transition in agreement with the experimental data.",0410128v1
+2004-10-22,Influence of disorder on Hc2-anisotropy and flux pinning in MgB2,"The upper critical field and flux pinning in MgB2 single crystals were
+investigated. The implications of these properties for technical applications
+are discussed and compared with transport properties of polycrystalline bulk
+samples and wires. In these untextured materials current percolation is
+important, especially at high magnetic fields. It is shown that the anisotropy
+of the upper critical field influences the ""irreversibility line"" and that the
+application range of MgB2 is limited by the smallest upper critical field
+(i.e., for the field direction perpendicular to the boron planes). Disorder,
+introduced by irradiation with neutrons, enhances the upper critical field,
+reduces the anisotropy and drastically changes flux pinning. While the enhanced
+Hc2 and the reduced anisotropy generally improve the transport properties of
+the polycrystalline samples, the contribution of the radiation-induced defects
+to flux pinning is small compared to the as-grown defect structure (grain
+boundary pinning).",0410573v1
+2004-11-21,Anisotropy of in-plane magnetization due to nodal gap structure in the vortex state,"We examine the interplay between anisotropy of the in-plane magnetization and
+the nodal gap structure on the basis of the approximate analytic solution in
+the quasiclassical formalism. We show that a four-fold oscillation appears in
+the magnetization, and its amplitude changes sign at an intermediate field. The
+high-field oscillation originates from the anisotropy of the upper critical
+field, while the low-field behavior can be understood by the thermally
+activated quasiparticles near nodes depending on the applied field angles. The
+temperature dependence of the magnetization also shows a similar sign change.
+The anisotropy of the magnetization offers a possible measurement to identify
+the gap structure directly for a wide class of type II superconductors.",0411540v1
+2004-12-21,Permeability anisotropy induced by a shear displacement,"The permeability anisotropy that results from a shear displacement 'u'
+between the complementary self-affine walls of a rough fracture is
+investigated. Experiments in which a dyed fluid displaces a transparent one as
+it is radially injected into a transparent fracture exhibit a clear anisotropy
+in the presence of shear displacements, and allow us to estimate the ratio of
+the permeabilities for flows parallel and perpendicular to 'u'. A simple model
+which accounts for the development of channels perpendicular to 'u'
+qualitatively explains these results, and predicts a permeability decreasing
+(increasing) linearly with the variance of the aperture field for flow parallel
+(perpendicular) to the shear displacement. These predictions are then compared
+to the results of numerical simulations performed using a lattice-Boltzmann
+technique and to the anisotropies measured in displacement experiments.",0412586v1
+2005-01-26,Anisotropic diffusion limited aggregation in three dimensions - universality and non-universality,"We explore the macroscopic consequences of lattice anisotropy for Diffusion
+Limited Aggregation (DLA) in three dimensions. Simple cubic and BCC lattice
+growths are shown to approach universal asymptotic states in a coherent
+fashion, and the approach is accelerated by the use of noise reduction. These
+states are strikingly anisotropic dendrites with a rich hierarchy of structure.
+For growth on an FCC lattice, our data suggest at least two stable fixed points
+of anisotropy, one matching the BCC case. Hexagonal growths, favouring six
+planar and two polar directions, appear to approach a line of asymptotic states
+with continuously tunable polar anisotropy. The more planar of these growths
+visually resemble real snowflake morphologies.
+  Our simulations use a new and dimension-independent implementation of the
+Diffusion Limited Aggregation (DLA) model. The algorithm maintains a hierarchy
+of sphere-coverings of the growth, supporting efficient random walks onto the
+growth by spherical moves. Anisotropy was introduced by restricting growth to
+certain preferred directions.",0501645v2
+2005-02-03,Current distribution and giant magnetoimpedance in composite wires with helical magnetic anisotropy,"The giant magnetoimpedance effect in composite wires consising of a
+non-magnetic inner core and soft magnetic shell is studied theoretically. It is
+assumed that the magnetic shell has a helical anisotropy. The current and field
+distributions in the composite wire are found by means of a simultaneous
+solution of Maxwell equations and the Landau-Lifshitz equation. The expressions
+for the diagonal and off-diagonal impedance are obtained for low and high
+frequencies. The dependences of the impedance on the anisotropy axis angle and
+the shell thickness are analyzed. Maximum field sensitivity is shown to
+correspond to the case of the circular anisotropy in the magnetic shell. It is
+demonstrated that the optimum shell thickness to obtain maximum impedance ratio
+is equal to the effective skin depth in the mahnetic material.",0502086v2
+2005-06-10,Anisotropy of the antiferromagnetic spin correlations in the superconducting state of YBa_2Cu_3O_7 and YBa_2Cu_4O_8,"We present evidence that the antiferromagnetic spin correlations in optimally
+doped YBa_2Cu_3O_7 and underdoped YBa_2Cu_4O_8 develop a surprisingly strong
+anisotropy in the superconducting state. Comparing the ratio of the nuclear
+spin-lattice relaxation rates of the planar copper and oxygen, measured at the
+lowest and highest temperatures as well as at T_c, we conclude that the
+antiferromagnetic in-plane correlations vanish as the temperature goes to zero.
+This observation is corroborated by the measurement of the copper linewidth in
+YBa_2Cu_4O_8. In contrast, the out-of-plane correlations do not change
+appreciably between T=T_c and T=0. Within a model of fluctuating fields this
+extreme anisotropy of the antiferromagnetic correlations also explains the
+observed temperature dependence of the anisotropy of the copper relaxation
+measured in a low external magnetic field.",0506245v2
+2005-06-10,"Anisotropic Magnetoresistance and Magnetic Anisotropy in High-quality (Ga,Mn)As Films","We have performed a systematic investigation of magnetotransport of a series
+of as-grown and annealed Ga1-xMnxAs samples with 0.011 <= x <= 0.09. We find
+that the anisotropic magnetoresistance (AMR) generally decreases with
+increasing magnetic anisotropy, with increasing Mn concentration and on low
+temperature annealing. We show that the uniaxial magnetic anisotropy can be
+clearly observed from AMR for the samples with x >= 0.02. This becomes the
+dominant anisotropy at elevated temperatures, and is shown to rotate by 90o on
+annealing. We find that the in-plane longitudinal resistivity depends not only
+on the relative angle between magnetization and current direction, but also on
+the relative angle between magnetization and the main crystalline axes. The
+latter term becomes much smaller after low temperature annealing. The planar
+Hall effect is in good agreement with the measured AMR indicating the sample is
+approximately in a single domain state throughout most of the magnetisation
+reversal, with a two-step magnetisation jump ascribed to domain wall nucleation
+and propagation.",0506250v1
+2005-06-22,Influence of the upper critical field anisotropy on the transport properties of polycrystalline MgB$_{2}$,"The intrinsic properties of MgB$_2$ form the basis for all applications of
+this superconductor. We wish to emphasize that the application range of
+polycrystalline MgB$_2$ is limited by the upper critical field H$_{c2}$ and its
+anisotropy. In wires or tapes, the MgB$_2$ grains are randomly oriented or only
+slightly textured and the anisotropy of the upper critical field leads to
+different transport properties in different grains, if a magnetic field is
+applied and the current transport becomes percolative. The irreversibility line
+is caused by the disappearance of a continuous superconducting current path and
+not by depinning as in high temperature superconductors. Based on a percolation
+model, we demonstrate how changes of the upper critical field and its
+anisotropy and how changes of flux pinning will influence the critical currents
+of a wire or a tape. These predictions are compared to results of neutron
+irradiation experiments, where these parameters were changed systematically.",0506562v1
+2005-08-03,Effects of an external magnetic field on the gaps and quantum corrections in an ordered Heisenberg antiferromagnet with Dzyaloshinskii-Moriya anisotropy,"We study the effects of external magnetic field on the properties of an
+ordered Heisenberg antiferromagnet with the Dzyaloshinskii-Moriya (DM)
+interaction. Using the spin-wave theory quantum correction to the energy,
+on-site magnetization, and uniform magnetization are calculated as a function
+of the field H and the DM anisotropy constant D. It is shown that the spin-wave
+excitations exhibit an unusual field-evolution of the gaps. This leads to
+various non-analytic dependencies of the quantum corrections on H and D. It is
+also demonstrated that, quite generally, the DM interaction suppresses quantum
+fluctuations, thus driving the system to a more classical ground state. Most of
+the discussion is devoted to the spin-S, two-dimensional square lattice
+antiferromagnet, whose S=1/2 case is closely realized in K2V3O8 where at H=0
+the DM anisotropy is hidden by the easy-axis anisotropy but is revealed in a
+finite field. The theoretical results for the field-dependence of the
+spin-excitation gaps in this material are presented and the implications for
+other systems are discussed.",0508114v2
+2005-11-01,Quasi-uniform in plane magnetization state of thin cylindrical dots in a square array and related anisotropy,"The energy (magnetostatic, exchange and Zeeman terms) of a square array of
+cylindrical sub-micron dots made of soft ferromagnetic material is calculated
+analytically and minimized, taking into account quasi-uniformity of dots
+magnetization. The dependence of the equilibrium energy of the array on the
+direction of the externally applied magnetic field in the array plane is
+recovered, exhibiting the four-fold anisotropy. The anisotropy constant is
+calculated. Its values for different array geometries are in excellent
+agreement to the recent independent experiments. New eight-fold anisotropy
+effect is predicted. Theory involves no adjustable parameters.",0511020v3
+2006-04-14,Can the Ising critical behavior survive in non-equilibrium synchronous cellular automata?,"Universality classes of Ising-like phase transitions are investigated in
+series of two-dimensional synchronously updated probabilistic cellular automata
+(PCAs), whose time evolution rules are either of Glauber type or of
+majority-vote type, and degrees of anisotropy are varied. Although early works
+showed that coupled map lattices and PCAs with synchronously updating rules
+belong to a universality class distinct from the Ising class, careful
+calculations reveal that synchronous Glauber PCAs should be categorized into
+the Ising class, regardless of the degree of anisotropy. Majority-vote PCAs for
+the system size considered yield exponents $\nu$ which are between those of the
+two classes, closer to the Ising value, with slight dependence on the
+anisotropy. The results indicate that the Ising critical behavior is robust
+with respect to anisotropy and synchronism for those types of non-equilibrium
+PCAs. There are no longer any PCAs known to belong to the non-Ising class.",0604379v3
+2006-04-27,Frozen metastable states in ordered systems of ultrafine magnetic particles,"For studying the interplay of dipolar interaction and anisotropy energy in
+systems of ultrafine magnetic particles we consider simple cubic systems of
+magnetic dipoles with anisotropy axes pointing into the $z$-direction. Using
+Monte Carlo simulations we study the magnetic relaxation from several initial
+states. We show explicitely that, due to the combined influence of anisotropy
+energy and dipole interaction, magnetic chains are formed along the
+$z$-direction that organize themselves in frozen metastable domains of columnar
+antiferromagnetic order. We show that the domains depend explicitely on the
+history and relax only at extremely large time scales towards the ordered
+state. We consider this as an indication for the appearence of frozen
+metastable states also in real sytems, where the dipoles are located in a
+liquid-like fashion and the anisotropy axes point into random directions.",0604620v1
+2006-05-08,Antiferromagnetic and spin gap phases of the anisotropic Kondo necklace model,"We have studied the effect of anisotropies on the quantum phase transition of
+the Kondo necklace model in dimensions D=1, 2 and 3. Both the anisotropy
+$\delta$ of the inter-site interaction term and anisotropy $\Delta$ of the
+on-site Kondo interaction have been included. We use a bond operator method
+with constraints implemented in mean field approximation. Starting from the
+paramagnetic phase we determine the critical ratio $(t/J)_c$ of the quantum
+critical point and associated scaling exponents of the Kondo-singlet gap. We
+show that in the case of easy-axis type anisotropy $\delta >1$ a qualitatively
+new behavior in comparison to the conventional Kondo necklace model with
+($\delta$,$\Delta$)=(0,1) appears. We have also obtained the antiferromagnetic
+order parameter in the long range ordered phase for $t > t_c$.",0605191v2
+2006-06-08,An ab-initio theory for the temperature dependence of magnetic anisotropy,"We present a first-principles theory of the variation of magnetic anisotropy,
+K, with temperature, T, in metallic ferromagnets. It is based on relativistic
+electronic structure theory and calculation of magnetic torque. Thermally
+induced `local moment' magnetic fluctuations are described within the
+relativistic generalisation of the `disordered local moment' (R-DLM) theory
+from which the T dependence of the magnetisation, m, is found. We apply the
+theory to a uniaxial magnetic material with tetragonal crystal symmetry,
+L1_0-ordered FePd, and find its uniaxial K consistent with a magnetic easy axis
+perpendicular to the Fe/Pd layers for all m and proportional to m squared for a
+broad range of values of m. This is the same trend that we have previously
+found in L1_0-ordered FePt and which agrees with experiment. This account,
+however, differs qualitatively from that extracted from a single ion anisotropy
+model. We also study the magnetically soft cubic magnet, the Fe(50)Pt(50) solid
+solution, and find that its small magnetic anisotropy constant K_1 rapidly
+diminishes from 8 micro-eV to zero. K evolves from being proportional to the
+seventh power of m at low T to the fourth power near the Curie temperature.",0606219v1
+2006-07-03,Monte Carlo study of the transverse susceptibility in ordered arrays of magnetic nanoparticles,"We present Monte Carlo simulations of the reversible transverse
+susceptibility (RTS) for a hexagonal array of dipolar interacting magnetic
+nanoparticles with random anisotropy. RTS curves with the bias-field in-plane
+and out-of-plane are compared. With increasing temperature the RTS curves
+evolve from a three-peak structure to a double-peak and eventually a
+single-peak at the blocking temperature of the system. This trend is preserved
+for weak interactions. Dipolar interactions at low temperature are responsible
+for the suppression of the coercivity peak in the out-of-plane geometry and its
+progressive merge to the anisotropy peak with decreasing interparticle
+separation in the in-plane geometry. The anisotropy peaks are located at higher
+field values in the out-of-plane geometry relative to the in-plane one. When
+the bias field lies in-plane (out-of-plane) the anisotropy peaks are shown to
+shift to lower (higher) field values with decreasing interparticle separation.
+The coercivity peak shifts to lower field values in both geometries. Our
+results are compared with recent experimental findings in self-assembled arrays
+of Fe nanoparticles.",0607037v2
+2006-10-06,Sensitivity of the interlayer magnetoresistance of layered metals to intralayer anisotropies,"Many of the most interesting and technologically important electronic
+materials discovered in the past two decades have two common features: a
+layered crystal structure and strong interactions between electrons. Two of the
+most fundamental questions about such layered metals concern the origin of
+intralayer anisotropies and the coherence of interlayer charge transport. We
+show that angle dependent magnetoresistance oscillations (AMRO) are sensitive
+to anisotropies around an intralayer Fermi surface. Hence, AMRO can be a probe
+of intralayer anisotropies that is complementary to angle-resolved
+photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM).
+However, AMRO are not very sensitive to the coherence of the interlayer
+transport. We illustrate this with comparisons to recent AMRO experiments on an
+overdoped cuprate.",0610191v2
+2006-11-08,Phase diagram of the spin-1 anisotropic Heisenberg model with a single-ion anisotropy,"The spin-1 anisotropic Heisenberg model with a single-ion anisotropy is
+studied using the Oguchi's pair approximation. Although the theory is developed
+for lattices with general coordination number, we treat in detail the
+three-dimensional lattice with the lowest coordination number, i.e. diamond
+lattice, where the critical and tricritical behavior of the system is analyzed
+as a function of both the single-ion anisotropy and exchange anisotropy.",0611212v2
+2006-11-10,Rotational hysteresis of the exchange anisotropy direction in Co/FeMn thin films,"We have investigated the effects of rotating an applied field on the exchange
+anisotropy in Co/FeMn thin films. When the applied field is initially along the
+cooling field direction, the longitudinal hysteresis loop has a maximum
+coercivity and the transverse hysteresis loop is flat, indicating that the
+exchange field is along the cooling field direction. When the applied field
+angle is rotated away and then restored to the original field cooling
+direction, the exchange anisotropy direction has changed. The rotation of the
+exchange field direction trails the applied field and is hysteretic. The
+rotational hysteresis of the exchange field direction is due to the weak
+anisotropy in thin FeMn layers, and decreases with increasing FeMn thickness.",0611294v1
+2006-11-17,Anisotropy and Penetration Depth of MgB$_{2}$ from ${}^{11}$B NMR,"The ${}^{11}$B NMR spectra in polycrystalline MgB$_2$ were measured for
+several magnetic fields (1.97 T and 3.15 T) as a function of temperature from 5
+K to 40 K. The composite spectra in the superconducting state can be understood
+in terms of anisotropy of the upper critical field, $\gamma_{H}$, which is
+determined to be 5.4 at low temperature. Using Brandt's algorithm\cite{Brandt}
+the full spectrum, including satellites, was simulated for the temperature 8 K
+and a magnetic field of 1.97 T. The penetration depth $\lambda$ was determined
+to be $1,152\pm50$ {\AA}, and the anisotropy of the penetration depth,
+$\gamma_{\lambda}$, was estimated to be close to one at low temperature.
+Therefore, our findings establish that there are two different anisotropies for
+upper critical field and penetration depth at low temperatures.",0611473v2
+2006-12-14,Importance of In-Plane Anisotropy in the Quasi Two-Dimensional Antiferromagnet BaNi$_{2}$V$_{2}$O$_{8}$,"The phase diagram of the quasi two-dimensional antiferromagnet
+BaNi$_{2}$V$_{2}$O$_{8}$ is studied by specific heat, thermal expansion,
+magnetostriction, and magnetization for magnetic fields applied perpendicular
+to $\mathbf{c}$. At $\mu_0H^{*}\simeq1.5$ T, a crossover to a high-field state,
+where $T_N(H)$ increases linearly, arises from a competition of intrinsic and
+field-induced in-plane anisotropies. The pressure dependences of $T_N$ and
+$H^{*}$ are interpreted using the picture of a pressure-induced in-plane
+anisotropy. Even at zero field and ambient pressure, in-plane anisotropy cannot
+be neglected, which implies deviations from pure
+Berezinskii-Kosterlitz-Thouless behavior.",0612357v2
+2007-01-10,Anisotropic susceptibility of the geometrically frustrated spin-chain compound Ca3Co2O6,"Ca3Co2O6 is a system exhibiting a series of fascinating properties, including
+magnetization plateaus and remarkably slow dynamics at low-T. These properties
+are intimately related to the geometrical frustration, which results from a
+particular combination of features: (i) the chains are arranged on a triangular
+lattice; (ii) there is a large uniaxial anisotropy; (iii) the intrachain and
+interchain couplings are ferromagnetic and antiferromagnetic, respectively.
+  The uniaxial anisotropy is thus an issue of crucial importance for the
+analysis of the physical properties of Ca3Co2O6. However, it turns out that no
+precise investigation of this magnetic anisotropy has been performed so far. On
+the basis of susceptibility data directly recorded on single crystals, the
+present study reports on quantitative information about the anisotropy of
+Ca3Co2O6.",0701192v1
+2007-01-25,Shape-induced phenomena in the finite size antiferromagnets,"It is of common knowledge that the direction of easy axis in the finite-size
+ferromagnetic sample is controlled by its shape. In the present paper we show
+that a similar phenomenon should be observed in the compensated
+antiferromagnets with strong magnetoelastic coupling. Destressing energy which
+originates from the long-range magnetoelastic forces is analogous to
+demagnetization energy in ferromagnetic materials and is responsible for the
+formation of equilibrium domain structure and anisotropy of macroscopic
+magnetic properties. In particular, crystal shape may be a source of additional
+uniaxial magnetic anisotropy which removes degeneracy of antiferromagnetic
+vector or artificial 4th order anisotropy in the case of a square cross-section
+sample. In a special case of antiferromagnetic nanopillars shape-induced
+anisotropy can be substantially enhanced due to lattice mismatch with the
+substrate. These effects can be detected by the magnetic rotational torque and
+antiferromagnetic resonance measurements.",0701631v2
+2007-01-29,"Magnetic Anisotropy, Spin Pinning and Exchange Constants of (Ga,Mn)As films","We present a detailed investigation of exchange-dominated nonpropagating
+spin-wave modes in a series of 100 nm Ga$_{1 - x}$Mn$_{x}$As films with Mn
+concentrations $x$ ranging from 0.02 to 0.08. The angular and Mn concentration
+dependences of spin wave resonance modes have been studied for both as-grown
+and annealed samples. Our results indicate that the magnetic anisotropy terms
+of Ga$_{1 - x}$Mn$_{x}$As depend on the Mn concentration $x$, but are also
+strongly affected by sample growth conditions; moreover, the magnetic
+anisotropy of Ga$_{1 - x}$Mn$_{x}$As films is found to be clearly linked to the
+Curie temperature. The spin wave resonance spectra consist of a series of well
+resolved standing spin-wave modes. The observed mode patterns are consistent
+with the Portis volume-inhomogeneity model, in which a spatially nonuniform
+anisotropy field acts on the Mn spins. The analysis of these exchange-dominated
+spin wave modes, including their angular dependences, allows us to establish
+the exchange stiffness constants for Ga$_{1 - x}$Mn$_{x}$As films.",0701717v1
+2007-02-12,Anisotropy and Order of Epitaxial Self-Assembled Quantum Dots,"Epitaxial self-assembled quantum dots (SAQDs) represent an important step in
+the advancement of semiconductor fabrication at the nanoscale that will allow
+breakthroughs in electronics and optoelectronics. In these applications, order
+is a key factor. Here, the role of crystal anisotropy in promoting order during
+early stages of SAQD formation is studied through a linear analysis of a
+commonly used surface evolution model. Elastic anisotropy is used a specific
+example. It is found that there are two relevant and predictable correlation
+lengths. One of them is related to crystal anisotropy and is crucial for
+determining SAQD order. Furthermore, if a wetting potential is included in the
+model, it is found that SAQD order is enhanced when the deposited film is
+allowed to evolve at heights near the critical surface height for
+three-dimensional film growth.",0702278v1
+1995-04-26,Statistics of the Microwave Background Anisotropies Caused by the Squeezed Cosmological Perturbations,"It is likely that the observed large-angular-scale anisotropies in the
+microwave background radiation are induced by the cosmological perturbations of
+quantum-mechanical origin. Such perturbations are now placed in squeezed vacuum
+quantum states and, hence, are characterized by large variances of their
+amplitude. The statistical properties of the anisotropies should reflect the
+underlying statistics of the squeezed vacuum quantum states. The theoretical
+variances for the temperature angular correlation function are derived and
+described quantitatively. It is shown that they are indeed large.
+Unfortunately, these large theoretical statistical uncertainties will make the
+extraction of cosmological information from the measured anisotropies a much
+more difficult problem than we wanted it to be.",9504045v1
+2005-09-16,Evidence for an anisotropy of the speed of light,"By comparing with the most recent experimental results, we point out the
+model dependence of the present bounds on the anisotropy of the speed of light.
+In fact, by replacing the CMB with a class of preferred frames that can better
+account for the experimental data, one obtains values of the RMS anisotropy
+parameter (1/2 -beta + delta) that are one order of magnitude larger than the
+presently quoted ones. The resulting non-zero anisotropy can be understood
+starting from the observation that the speed of light in the Earth's
+gravitational field is not the basic parameter c=1 entering Lorentz
+transformations. In this sense, light can propagate isotropically only in one
+`preferred' frame.",0509066v1
+1998-06-06,Non-perturbative determination of anisotropy coefficients in lattice gauge theories,"We propose a new non-perturbative method to compute derivatives of gauge
+coupling constants with respect to anisotropic lattice spacings (anisotropy
+coefficients), which are required in an evaluation of thermodynamic quantities
+from numerical simulations on the lattice. Our method is based on a precise
+measurement of the finite temperature deconfining transition curve in the
+lattice coupling parameter space extended to anisotropic lattices by applying
+the spectral density method. We test the method for the cases of SU(2) and
+SU(3) gauge theories at the deconfining transition point on lattices with the
+lattice size in the time direction $N_t=4$ -- 6. In both cases, there is a
+clear discrepancy between our results and perturbative values. A longstanding
+problem, when one uses the perturbative anisotropy coefficients, is a
+non-vanishing pressure gap at the deconfining transition point in the SU(3)
+gauge theory. Using our non-perturbative anisotropy coefficients, we find that
+this problem is completely resolved: we obtain $\Delta p/T^4 = 0.001(15)$ and
+$-0.003(17)$ on $N_t=4$ and 6 lattices, respectively.",9806007v1
+2001-08-06,Classically Perfect Gauge Actions on Anisotropic Lattices,"We present a method for constructing classically perfect anisotropic actions
+for SU(3) gauge theory based on an isotropic Fixed Point Action. The action is
+parametrised using smeared (``fat'') links. The construction is done explicitly
+for anisotropy $\xi=a_s/a_t=2$ and 4. The corresponding renormalised
+anisotropies are determined using the torelon dispersion relation. The
+renormalisation of the anisotropy is small and the parametrisation describes
+the true action well. Quantities such as the static quark-antiquark potential,
+the critical temperature of the deconfining phase transition and the low-lying
+glueball spectrum are measured on lattices with anisotropy $\xi=2$. The mass of
+the scalar $0^{++}$ glueball is determined to be 1580(60) MeV, while the tensor
+$2^{++}$ glueball is at 2430(60) MeV.",0108005v1
+2002-08-06,One loop calculation of the renormalised anisotropy for improved anisotropic gluon actions on a lattice,"Using the infrared dispersion relation of the on shell gluon, we calculate
+the renormalisation of the the anisotropy to one loop in perturbation theory
+for lattice Yang-Mills theories, including the Wilson action and actions with
+Symanzik and/or tadpole improvement. Using twisted boundary conditions as a
+gauge invariant infrared regulator, we show for an SU(3) gauge group in D=3+1
+dimensions that the one loop anisotropy is accurate to O(3%) for a range of g^2
+and chi covering current simulations. In doing so we also present Feynman rules
+for SU(N) gauge groups with generic anisotropy structure (including `3+1' and
+`2+2' cases).",0208010v2
+2004-01-06,Numerical study of staggered quark action on quenched anisotropic lattices,"The staggered quark action on anisotropic lattices is studied. We carry out
+numerical simulations in the quenched approximation at three values of lattice
+spacing ($a_{\sigma}^{-1}=1-2$ GeV) with the anisotropy $\xi=
+a_{\sigma}/a_{\tau}=4$, where $a_{\sigma}$ and $a_{\tau}$ are the spatial and
+temporal lattice spacings, respectively. The bare anisotropy $\gamma_F$ in the
+quark action is numerically tuned through the ratio of meson masses in the fine
+and coarse directions, and through the dispersion relation of a meson, so that
+the renormalized fermionic anisotropy coincides with that of the gauge field.
+The discrepancy between these two calibration schemes provides an estimate of
+the finite lattice artifact, which is found to be sizable in the range of
+cutoff explored in this work. We also compute the meson masses using
+correlators with the wall source at the tuned anisotropy parameter. The flavor
+symmetry breaking effect smoothly decreases as $\beta$ increases. The effect of
+uncertainty in $\gamma_F$ on the meson masses are examined. We also discuss a
+perspective on dynamical simulations.",0401009v1
+2005-09-13,Fermion propagators in QED3 with velocity anisotropies,"QED3 with fermi and gap anisotropies is considered to be a candidate
+effective field theory of high temperature superconductors. Simulations of a
+variant of the theory have demonstrated that there is evidence consistent with
+a phase transition to a chirally restored phase as the velocity anisotropy
+increases, and that the correlation lengths of pions in spatial directions
+behave in a manner consistent with the anisotropy being a relevant parameter of
+the theory. We present the first measurements of the fermion propagator in
+Landau gauge for this theory and suggest that the structure of this theory is
+more complex than previously thought.",0509038v2
+1993-05-13,Degree Scale Microwave Anisotropies in NonGaussian Theories of Cosmic Structure Formation,"The COBE satellite's maps of the cosmic microwave background (CMB) anisotropy
+do not have the resolution to discriminate between theories of cosmic structure
+formation based on inflation, and those based on field ordering following a
+symmetry breaking phase transition. For this purpose it is critical to resolve
+the CMB anisotropy on degree scales. In this paper we report on detailed
+calculations of the degree scale anisotropies predicted in the global string,
+monopole, texture and nontopological texture scenarios of structure formation,
+emphasising their distinct character from those predicted by inflation, and
+commenting on the prospects of their detection in the near future.",9305261v1
+2004-06-17,Collective modes of an Anisotropic Quark-Gluon Plasma II,"We continue our exploration of the collective modes of an anisotropic quark
+gluon plasma by extending our previous analysis to arbitrary Riemann sheets. We
+demonstrate that in the presence of momentum-space anisotropies in the parton
+distribution functions there are new relevant singularities on the neighboring
+unphysical sheets. We then show that for sufficiently strong anisotropies that
+these singularities move into the region of spacelike momentum and their effect
+can extend down to the physical sheet. In order to demonstrate this explicitly
+we consider the polarization tensor for gluons propagating parallel to the
+anisotropy direction. We derive analytic expressions for the gluon structure
+functions in this case and then analytically continue them to unphysical
+Riemann sheets. Using the resulting analytic continuations we numerically
+determine the position of the unphysical singularities. We then show that in
+the limit of infinite contraction of the distribution function along the
+anisotropy direction that the unphysical singularities move onto the physical
+sheet and result in real spacelike modes at large momenta for all
+""out-of-plane"" angles of propagation.",0406188v1
+2004-08-25,Collisional Energy Loss of a Heavy Quark in an Anisotropic Quark-Gluon Plasma,"We compute the leading-order collisional energy loss of a heavy quark
+propagating through a quark-gluon plasma in which the quark and gluon
+distributions are anisotropic in momentum space. Following the calculation
+outlined for QED in an earlier work we indicate the differences encountered in
+QCD and their effect on the collisional energy loss results. For a 20 GeV
+bottom quark we show that momentum space anisotropies can result in the
+collisional heavy quark energy loss varying with the angle of propagation by up
+to 50%. For low velocity quarks we show that anisotropies result in energy gain
+instead of energy loss with the energy gain focused in such a way as to
+accelerate particles along the anisotropy direction thereby reducing the
+momentum-space anisotropy. The origin of this negative energy loss is
+explicitly identified as being related to the presence of plasma instabilities
+in the system.",0408275v1
+2004-11-17,Anomalous scaling of passively advected magnetic field in the presence of strong anisotropy,"Inertial-range scaling behavior of high-order (up to order N=51) structure
+functions of a passively advected vector field has been analyzed in the
+framework of the rapid-change model with strong small-scale anisotropy with the
+aid of the renormalization group and the operator-product expansion. It has
+been shown that in inertial range the leading terms of the structure functions
+are coordinate independent, but powerlike corrections appear with the same
+anomalous scaling exponents as for the passively advected scalar field. These
+exponents depend on anisotropy parameters in such a way that a specific
+hierarchy related to the degree of anisotropy is observed. Deviations from
+power-law behavior like oscillations or logarithmic behavior in the corrections
+to structure functions have not been found.",0411040v1
+2005-07-23,Discrete Solitons and Vortices on Anisotropic Lattices,"We consider effects of anisotropy on solitons of various types in
+two-dimensional nonlinear lattices, using the discrete nonlinear
+Schr{\""{o}}dinger equation as a paradigm model. For fundamental solitons, we
+develop a variational approximation, which predicts that broad quasi-continuum
+solitons are unstable, while their strongly anisotropic counterparts are
+stable. By means of numerical methods, it is found that, in the general case,
+the fundamental solitons and simplest on-site-centered vortex solitons (""vortex
+crosses"") feature enhanced or reduced stability areas, depending on the
+strength of the anisotropy. More surprising is the effect of anisotropy on the
+so-called ""super-symmetric"" intersite-centered vortices (""vortex squares""),
+with the topological charge $S$ equal to the square's size $M$: we predict in
+an analytical form by means of the Lyapunov-Schmidt theory, and confirm by
+numerical results, that arbitrarily weak anisotropy results in dramatic changes
+in the stability and dynamics in comparison with the \emph{degenerate}, in this
+case, isotropic limit.",0507048v1
+2006-09-28,Numerical Investigation of Scaling Regimes in a Model of Anisotropically Advected Vector Field,"Influence of strong uniaxial small-scale anisotropy on the stability of
+inertial-range scaling regimes in a model of a passive transverse vector field
+advected by an incompressible turbulent flow is investigated by means of the
+field theoretic renormalization group. Turbulent fluctuations of the velocity
+field are taken in the form of a Gaussian statistics with zero mean and defined
+noise with finite correlations in time. It is shown that stability of the
+inertial-range scaling regimes in the three-dimensional case is not destroyed
+by anisotropy but the corresponding stability of the two-dimensional system can
+be corrupted by the presence of anisotropy. A borderline dimension $d_c$ below
+which the stability of the scaling regime is not present is calculated as a
+function of anisotropy parameters.",0609067v1
+2004-06-21,Azimuthal Anisotropy of Photon and Charged Particle Emission in Pb+Pb Collisions at 158 A GeV/c,"The azimuthal distributions of photons and charged particles with respect to
+the event plane are investigated as a function of centrality in Pb + Pb
+collisions at 158 A GeV/c in the WA98 experiment at the CERN SPS. The
+anisotropy of the azimuthal distributions is characterized using a Fourier
+analysis. For both the photon and charged particle distributions the first two
+Fourier coefficients are observed to decrease with increasing centrality. The
+observed anisotropies of the photon distributions compare well with the
+expectations from the charged particle measurements for all centralities.",0406022v2
+1996-01-12,Dilepton anisotropy from $p + Be$ and $Ca + Ca$ collisions at BEVALAC energies,"A full calculation of lepton-pair angular characteristics is carried out for
+$e^+e^-$ pairs created in $p + Be$ and $Ca + Ca$ collisions from 1.0 to 2.1
+GeV/A. It is demonstrated that the dilepton decay anisotropy depends
+sensitively on the different sources and may be used for their disentangling.
+Due to the dominance of the $\eta$-and $\Delta$-Dalitz decays and only a small
+anisotropy coefficient for $\pi^+\pi^-$ annihilation, the expected anisotropy
+coefficients show a decrease with invariant mass of the dilepton pair and
+change only moderately when comparing $p + Be$ and $Ca + Ca$ reactions at the
+same bombarding energy.",9601018v1
+1996-05-17,Probing Hadronic Polarizations with Dilepton Anisotropies,"We investigate the production of $e^+e^-$ pairs from $p + Be$ and
+nucleus-nucleus collisions from 2 GeV/A to 200 GeV/A within a covariant
+transport approach and focus on the dilepton angular anisotropies as a function
+of the dilepton invariant mass. Whereas the low mass regime yields information
+about the Dalitz decays of the $\Delta, \eta$ and $\omega$, above M $\approx
+$0.5 GeV the angular anisotropies provide additional information about the
+$\pi^+\pi^- \to \rho^0 \to e^+e^-$ channel in the medium. The anisotropy
+coefficient is found to change its sign for M $>$ 0.5 GeV in case of
+nucleus-nucleus reactions when increasing the bombarding energy from 2 GeV/A to
+200 GeV/A which sheds some light on the $\pi \pi \to \rho$ dynamics.",9605025v1
+2001-06-04,Passive scalar anisotropy in a heated turbulent wake: new observations and implications for LES,"The effects of passive scalar anisotropy on subgrid-scale (SGS) physics and
+modeling for Large-Eddy Simulations are studied experimentally. Measurements
+are performed across a moderate Reynolds number wake flow generated by a heated
+cylinder, using an array of four X-wire and four cold-wire probes. By varying
+the separation distance among probes in the array, we obtain filtered and
+subgrid quantities at three different filter sizes. We compute several terms
+that comprise the subgrid dissipation tensor of kinetic energy and
+scalar-variance and test for isotropic behavior, as a function of filter scale.
+We find that whereas the kinetic energy dissipation tensor tends towards
+isotropy at small scales, the SGS scalar-variance dissipation remains
+anisotropic independent of filter scale. The eddy-diffusion model predicts
+isotropic behavior, whereas the nonlinear (or tensor eddy diffusivity) model
+reproduces the correct trends, but overestimates the level of scalar
+dissipation anisotropy. These results provide some support for so-called mixed
+models but raise new questions about the causes of the observed anisotropy.",0106014v1
+2001-11-21,Interpreting Compton anisotropy of ice Ih: a cluster partitioning method,"We propose a simple cluster-based method with application to calculations of
+Compton profile anisotropies of ice. The convergence of the method is checked
+with respect to Crystal95 results. Increasing both basis-set quality and
+cluster sizes results in a decrease of the magnitude of theoretical Compton
+anisotropies. The agreement with experimental data is therefore improved
+towards previously calculated anisotropies. Moreover, analyzing directional
+autocorrelation functions shows an evidence for both anti-bonding and
+polarization effects.",0111157v2
+2006-12-21,Re-Analysis of the Marinov Light-Speed Anisotropy Experiment,"The anisotropy of the speed of light at 1 part in 10^3 has been detected by
+Michelson and Morley (1887), Miller (1925/26), Illingworth (1927), Joos (1930),
+Jaseja et al. (1964), Torr and Kolen (1984), De Witte (1991) and Cahill (2006)
+using a variety of experimental techniques, from gas-mode Michelson
+interferometers (with the relativistic theory for these only determined in
+2002) to one-way RF coaxial cable propagation timing. All agree on the speed,
+right ascension and declination of the anisotropy velocity. The Stephan Marinov
+experiment (1984) detected a light speed anisotropy using a mechanical coupled
+shutters technique which has holes in co-rotating disks, essentially a one-way
+version of the Fizeau mechanical round-trip speed-of-light experiment. The
+Marinov data is re-analysed herein because the velocity vector he determined is
+in a very different direction to that from the above experiments. No
+explanation for this difference has been uncovered.",0612201v2
+2007-05-29,A Study on anisotropy of cosmic ray distribution with a small array of water-cherenkov detectors,"The study of the anisotropy of the arrival directions is an essential tool to
+investigate the origin and propagation of cosmic rays primaries. A simple way
+of recording many cosmic rays is to record coincidences between a number of
+detectors. We have monitored multi-TeV cosmic rays by a small array of water
+cherenkov detectors in Tehran(35 43 N, 51 20 E, 1200m a.s.l). More than
+1.1*10^6 extensive air shower events were recorded. In addition to the Compton-
+Getting effect due to the motion of the earth in the Galaxy, an anisotropy has
+been observed which is due to a unidirectional anisotropy of cosmic ray flow
+along the Galactic arms.",0705.4234v1
+2007-06-21,Tuning the domain wall orientation in thin magnetic strips by induced anisotropy,"We report on a method to tune the orientation of in-plane magnetic domains
+and domain walls in thin ferromagnetic strips by manipulating the magnetic
+anisotropy. Uniaxial in-plane anisotropy is induced in a controlled way by
+oblique evaporation of magnetic thin strips. A direct correlation between the
+magnetization direction and the domain wall orientation is found experimentally
+and confirmed by micromagnetic simulations. The domain walls in the strips are
+always oriented along the oblique evaporation-induced easy axis, in spite of
+the shape anisotropy. The controlled manipulation of domain wall orientations
+could open new possibilities for novel devices based on domain-wall
+propagation.",0706.3106v1
+2007-07-06,Zero-temperature behavior of the random-anisotropy model in the strong-anisotropy limit,"We consider the random-anisotropy model on the square and on the cubic
+lattice in the strong-anisotropy limit. We compute exact ground-state
+configurations, and we use them to determine the stiffness exponent at zero
+temperature; we find $\theta = -0.275(5)$ and $\theta \approx 0.2$ respectively
+in two and three dimensions. These results show that the low-temperature phase
+of the model is the same as that of the usual Ising spin-glass model. We also
+show that no magnetic order occurs in two dimensions, since the expectation
+value of the magnetization is zero and spatial correlation functions decay
+exponentially. In three dimensions our data strongly support the absence of
+spontaneous magnetization in the infinite-volume limit.",0707.1005v1
+2007-07-17,The behavior of non-linear anisotropies in bouncing Bianchi I models of loop quantum cosmology,"In homogeneous and isotropic loop quantum cosmology, gravity can behave
+repulsively at Planckian energy densities leading to the replacement of the big
+bang singularity with a big bounce. Yet in any bouncing scenario it is
+important to include non-linear effects from anisotropies which typically grow
+during the collapsing phase. We investigate the dynamics of a Bianchi I
+anisotropic model within the framework of loop quantum cosmology. Using
+effective semi-classical equations of motion to study the dynamics, we show
+that the big bounce is still predicted with only differences in detail arising
+from the inclusion of anisotropies. We show that the anisotropic shear term
+grows during the collapsing phase, but remains finite through the bounce.
+Immediately following the bounce, the anisotropies decay and with the inclusion
+of matter with equation of state $w < +1$, the universe isotropizes in the
+expanding phase.",0707.2548v1
+2007-09-17,X-Ray Analysis of Oxygen-induced Perpendicular Magnetic Anisotropy in Pt/Co/AlOx trilayer,"X-ray spectroscopy measurements have been performed on a series of Pt/Co/AlOx
+trilayers to investigate the role of Co oxidation in the perpendicular magnetic
+anisotropy of the Co/AlOx interface. It is observed that high temperature
+annealing modifies the magnetic properties of the Co layer, inducing an
+enhancement of the perpendicular magnetic anisotropy. The microscopic
+structural properties are analyzed via X-ray Absorption Spectroscopy, X-ray
+Magnetic Circular Dichroism and X-ray Photoelectron Spectroscopy measurements.
+It is shown that annealing enhances the amount of interfacial oxide, which may
+be at the origin of a strong perpendicular magnetic anisotropy.",0709.2581v2
+2007-10-03,Evidence of random magnetic anisotropy in ferrihydrite nanoparticles based on analysis of statistical distributions,"We show that the magnetic anisotropy energy of antiferromagnetic ferrihydrite
+depends on the square root of the nanoparticles volume, using a method based on
+the analysis of statistical distributions. The size distribution was obtained
+by transmission electron microscopy, and the anisotropy energy distributions
+were obtained from ac magnetic susceptibility and magnetic relaxation. The
+square root dependence corresponds to random local anisotropy, whose average is
+given by its variance, and can be understood in terms of the recently proposed
+single phase homogeneous structure of ferrihydrite.",0710.0864v1
+2007-12-08,The shape of invasion perclation clusters in random and correlated media,"The shape of two-dimensional invasion percolation clusters are studied
+numerically for both non-trapping (NTIP) and trapping (TIP) invasion
+percolation processes. Two different anisotropy quantifiers, the anisotropy
+parameter and the asphericity are used for probing the degree of anisotropy of
+clusters. We observe that in spite of the difference in scaling properties of
+NTIP and TIP, there is no difference in the values of anisotropy quantifiers of
+these processes. Furthermore, we find that in completely random media, the
+invasion percolation clusters are on average slightly less isotropic than
+standard percolation clusters. Introducing isotropic long-range correlations
+into the media reduces the isotropy of the invasion percolation clusters. The
+effect is more pronounced for the case of persisting long-range correlations.
+The implication of boundary conditions on the shape of clusters is another
+subject of interest. Compared to the case of free boundary conditions, IP
+clusters of conventional rectangular geometry turn out to be more isotropic.
+Moreover, we see that in conventional rectangular geometry the NTIP clusters
+are more isotropic than TIP clusters.",0712.1287v2
+2007-12-13,Breakdown of an intermediate plateau in the magnetization process of anisotropic spin-1 Heisenberg dimer: theory vs. experiment,"The magnetization process of the spin-1 Heisenberg dimer model with axial and
+rhombic single-ion anisotropy terms is particularly investigated in connection
+with recent experimental high-field measurements performed on the
+single-crystal sample of the homodinuclear nickel(II) compound
+[Ni2(Medpt)2(ox)(H2O)2](ClO4)2.2H2O (Medpt=methyl-bis(3-aminopropyl)amine). The
+results obtained from the exact numerical diagonalization reveal a striking
+magnetization process with a marked spatial dependence on the applied magnetic
+field for arbitrary but non-zero single-ion anisotropy. It is demonstrated that
+the field range, which corresponds to an intermediate magnetization plateau
+emerging at a half of the saturation magnetization, basically depends on
+single-ion anisotropy terms as well as a spatial orientation of the applied
+field. The breakdown of the intermediate magnetization plateau is discussed at
+length in relation to the single-ion anisotropy strength.",0712.2109v2
+2007-12-14,The Spin Reorientation Transition and Phase Diagram of Ultrathin Ferromagnetic Films,"We show results from Monte Carlo simulations of a two dimensional Heisenberg
+model for ultrathin films with perpendicular anisotropy. A complete phase
+diagram is obtained as a function of anisotropy and temperature, spanning a
+wide range of behavior. We discuss our results in relation with experimental
+findings in different ultrathin films. We observe and characterize a line of
+Spin Reorientation Transitions . This transition from out of plane stripe order
+to in plane ferromagnetic order presents a paramagnetic gap in between in a
+finite region in parameter space, as reported in experiments. For large
+anisotropies direct transitions from a low temperature stripe phase to a
+paramagnetic or tetragonal phase with dominant perpendicular magnetization is
+observed, also in agreement with experiments.
+  We also show the phase diagram for a system without exchange, i.e. with pure
+dipolar and anisotropy interactions. It shows a similar behavior to the
+ferromagnetic case with antiferromagnetic instead of stripe phases at low
+temperatures. A Spin Reorientation Transition is also found in this case.",0712.2426v1
+2007-12-15,Second-order power spectra of CMB anisotropies due to primordial random perturbations in flat cosmological models,"Second-order power spectra of Cosmic Microwave Background (CMB) anisotropies
+due to random primordial perturbations at the matter dominant stage are
+studied, based on the relativistic second-order theory of perturbations in flat
+cosmological models and on the second-order formula of CMB anisotropies derived
+by Mollerach and Matarrese. So far the second-order integrated Sachs-Wolfe
+effect has been analyzed using the three-point correlation or bispectrum. In
+this paper we derive the second-order term of power spectra given using the
+two-point correlation of temperature fluctuations.
+  The second-order density perturbations are small, compared with the
+first-order ones. The second-order power spectra of CMB anisotropies, however,
+are not small at all, compared with the first-order power spectra, because at
+the early stage the first-order integrated Sachs-Wolfe effect is very small and
+the second-order integrated Sachs-Wolfe effect may be dominant over the
+first-order ones. So their characteristic behaviors may be measured through the
+future precise observation and bring useful informations on the structure and
+evolution of our universe in the future.",0712.2511v3
+2008-01-30,Femtosecond Control of the Magnetization in Ferromagnetic Semiconductors,"We develop a theory of collective spin dynamics triggered by ultrafast
+optical excitation of ferromagnetic semiconductors. Using the density matrix
+equations of motion in the mean field approximation and including magnetic
+anisotropy and hole spin dephasing effects, we predict the development of a
+light--induced magnetization tilt during ultra--short time intervals comparable
+to the pulse duration. This femtosecond dynamics in the coherent temporal
+regime is governed by the interband nonlinear optical polarizations and is
+followed by a second temporal regime governed by the magnetic anisotropy of the
+Fermi sea. We interpret our numerical results by deriving a
+Landau--Gilbert--like equation for the collective spin, which demonstrates an
+ultrafast correction to the magnetic anisotropy effective field due to second
+order coherent nonlinear optical processes. Using the Lindblad semigroup
+method, we also derive a contribution to the interband polarization dephasing
+determined by the Mn spin and the hole spin dephasing. Our predicted
+magnetization tilt and subsequent nonlinear dynamics due to the magnetic
+anisotropy can be controlled by varying the optical pulse intensity, duration,
+and helicity and can be observed with pump--probe magneto--optical
+spectroscopy.",0801.4641v1
+2008-03-27,Tuning for Three-flavors of Anisotropic Clover Fermions with Stout-link Smearing,"In this work we perform the parameter tuning of three flavors of dynamical
+clover quarks on anisotropic lattices. The fermion action uses
+three-dimensional spatial stout-link smearing. The gauge anisotropy is
+determined in a small box with Schr\""odinger background using Wilson-loop
+ratios. The fermion anisotropy is obtained from studying the meson dispersion
+relation with antiperiodic boundary conditions in the time direction. The
+spatial and temporal clover coefficients are fixed to the tree-level
+tadpole-improved values, and we demonstrate that they satisfy the
+nonperturbative conditions as determined by the Schr\""odinger functional
+method. For the desired lattice spacing $a_s\approx 0.12$ fm and renormalized
+anisotropy $\xi=3.5$, we find the gauge and fermionic anisotropies can be fixed
+to quark mass independent values up through the strange quark mass. This work
+lays the foundation needed for further studies of the excited-state hadron
+spectrum.",0803.3960v2
+2008-04-07,Cosmic Strings as the Source of Small-Scale Microwave Background Anisotropy,"Cosmic string networks generate cosmological perturbations actively
+throughout the history of the universe. Thus, the string sourced anisotropy of
+the cosmic microwave background is not affected by Silk damping as much as the
+anisotropy seeded by inflation. The spectrum of perturbations generated by
+strings does not match the observed CMB spectrum on large angular scales
+(l<1000) and is bounded to contribute no more than 10% of the total power on
+those scales. However, when this bound is marginally saturated, the anisotropy
+created by cosmic strings on small angular scales l>2000 will dominate over
+that created by the primary inflationary perturbations. This range of angular
+scales in the CMB is presently being measured by a number of experiments; their
+results will test this prediction of cosmic string networks soon.",0804.0810v2
+2008-04-15,Anisotropy and Morphology of Strained III-V Heteroepitaxial Films,"Strained coherent heteroepitaxy of III-V semiconductor films such as
+In$_x$Ga$_{1-x}$As/GaAs has potential for electronic and optoelectronic
+applications such as high density logic, quantum computing architectures, laser
+diodes, and other optoelectronic devices. Crystal symmetry can have a large
+effect on the morphology of these films and their spatial order. Often the
+formation of group IV strained heterostructures such as Ge deposited on Si is
+analyzed using analytic models based on the Asaro-Tiller-Grinfeld instability.
+However, the governing dynamics of III-V 3D heterostructure formation has
+different symmetry and is more anisotropic. The additional anisotropy appears
+in both the surface energy and the diffusivity. Here, the resulting anisotropic
+governing dynamics are studied to linear order. The resulting possible film
+morphologies are compared with experimentally observed In$_x$Ga$_{1-x}$As/GaAs
+films. Notably it is found that surface-energy anisotropy plays a role at least
+as important as surface diffusion anisotropy if not more so, in contrast to
+previous suppositions.",0804.2438v3
+2008-04-18,Effect of anisotropic hopping on the Bose Hubbard model phase diagram: strong-coupling perturbation theory on a square lattice,"There has been a recent resurgence of experimental efforts to quantitatively
+determine the phase diagram of the Bose Hubbard model by carefully analyzing
+experiments with ultracold bosonic atoms on an optical lattice. In many
+realizations of these experiments, the hopping amplitudes are not homogeneous
+throughout the lattice, but instead, the lattice has an anisotropy where
+hopping along one direction is not exactly equal to hopping along a
+perpendicular direction. In this contribution, we examine how an anisotropy in
+the hopping matrix elements affects the Mott lobes of the Bose Hubbard model.
+For weak anisotropy, we find the phase diagram is only slightly modified when
+expressed in terms of the average hopping, while for strong anisotropy, one
+expects to ultimately see dimensional crossover effects.",0804.3040v1
+2008-06-18,Space-time anisotropy: theoretical issues and the possibility of an observational test,"The specific astrophysical data collected during the last decade causes the
+need for the modification of the expression for the Einstein-Hilbert action,
+and several attempts sufficing this need are known. The modification suggested
+in this paper stems from the possible anisotropy of space-time and this means
+the natural change of the simplest scalar in the least action principle. To
+provide the testable support to this idea, the optic-metrical parametric
+resonance is regarded - an experiment on the galactic scale based on the
+interaction between the electromagnetic radiation of cosmic masers and
+periodical gravitational waves emitted by close double systems or pulsars.
+Since the effect depends on the space-time metric, the possible anisotropy
+could reveal itself through observations. To give the corresponding theory
+predicting the corrections to the expected results of the experiment, the
+specific mathematical formalism of Finsler geometry was chosen. It was found
+that in case the anisotropy of the space-time exists, the orientation of the
+astrophysical systems suitable for observations would show it. In the obtained
+geodesics equation there is a direction dependent term.",0806.3066v2
+2008-09-05,CMB Anisotropy Induced by a Moving Straight Cosmic String,"We showed that the part of strings could be detected by optical method is
+only 20% from the total available amount of such objects, therefore the
+gravitational lensing method has to be ""completed"" by CMB one. We found the
+general structure of the CMB anisotropy generated by a cosmic string for simple
+model of straight string moving with constant velocity. For strings with
+deficit angle 1-2 arcsec the amplitude of generated anisotropy has to be 15-30
+muK (the corresponding string linear density is (G mu) ~ 10^{-7} and energy is
+GUT one, 10^{15} GeV). To use both radio and optical methods the deficit angle
+has to be from 0.1 arcsec to 5-6 arcsec. If cosmic string can be detected by
+optical method, the length of corresponding brightness spot of anisotropy has
+to be no less than 100 degrees.",0809.0992v1
+2008-09-26,Photons from anisotropic Quark-Gluon-Plasma,"We calculate medium photons due to Compton and annihilation processes in an
+anisotropic media. The effects of time-dependent momentum-space anisotropy of
+{\em Quark-Gluon-Plasma} (QGP) on the medium photon production are discussed.
+Such an anisotropy can results from the initial rapid longitudinal expansion of
+the matter, created in relativistic heavy ion collisions. A phenomenological
+model for the time-dependence of the parton hard momentum scale,
+$p_{hard}(\tau)$, and anisotropy parameter, $\xi(\tau)$, has been used to
+describe the plasma space-time evolution. We find significant dependency of
+photon yield on the isotropization time ($\tau_{iso}$). It is shown that the
+introduction of early time momentum-space anisotropy can enhance the photon
+production by a factor of $10 (1.5)$ (in the central rapidity region) for {\em
+free streaming} ({\em collisionally-broadened}) {\em interpolating} model if we
+assume fixed initial condition. On the other hand, enforcing the fixed final
+multiplicity significantly reduces the enhancement of medium photon production.",0809.4596v3
+2008-12-30,Quasistatic behavior and force transmission in packing of irregular polyhedral particles,"Dense packings composed of irregular polyhedral particles are investigated by
+numerical simulations under quasistatic triaxial compression. The Contact
+Dynamics method is used for this investigation with 40 000 particles. The
+effect of particle shape is analyzed by comparing this packing with a packing
+of similar particle size distribution but with spherical particles. We analyze
+the origin of the higher shear strength of the polyhedra packing by considering
+various anisotropy parameters characterizing the microstructure and force
+transmission. Remarkably, we find that the polyhedra packing has a lower fabric
+anisotropy in terms of branch vectors (joining the particle centers) than the
+sphere packing. In contrast, the polyhedra packing shows a much higher force
+anisotropy which is at the origin of its higher shear strength. The force
+anisotropy in the polyhedra packing is shown to be related to the formation of
+face-face contacts. In particular, most face-face contacts belong to strong
+force chains along the major principal stress direction whereas vertex-face and
+edge-edge contacts are correlated with weak forces and oriented on average
+along the minor principal stress direction in steady shearing.",0812.5060v1
+2009-01-05,Anisotropic spatially heterogeneous dynamics on the $α$ and $β$ relaxation time scales studied via a four-point correlation function,"We examine the anisotropy of a four-point correlation function
+$G_4(\vec{k},\vec{r};t)$ and it's associated structure factor
+$S_4(\vec{k},\vec{q};t)$ calculated using Brownian Dynamics computer
+simulations of a model glass forming system. These correlation functions
+measure the spatial correlations of the relaxation of different particles, and
+we examine the time and temperature dependence of the anisotropy. We find that
+the anisotropy is strongest at nearest neighbor distances at time scales
+corresponding to the peak of the non-Gaussian parameter $\alpha_2(t) = 3 <
+\delta r^4(t) >/[ 5 < \delta r^2(t) >^2] - 1$, but is still pronounced around
+the $\alpha$ relaxation time. We find that the structure factor
+$S_4(\vec{k},\vec{q};t)$ is anisotropic even for the smallest wave vector
+accessible in our simulation suggesting that our system (and other systems
+commonly used in computer simulations) may be too small to extract the $\vec{q}
+\to 0$ limit of the structure factor. We find that the determination of a
+dynamic correlation length from $S_4(\vec{k},\vec{q};t)$ is influenced by the
+anisotropy. We extract an effective anisotropic dynamic correlation length from
+the small $q$ behavior of $S_4(\vec{k},\vec{q};t)$.",0901.0493v1
+2009-01-21,Finite-size anisotropy in statistically uniform porous media,"Anisotropy of the permeability tensor in statistically uniform porous media
+of sizes used in typical computer simulations is studied. Although such systems
+are assumed to be isotropic by default, we show that de facto their anisotropic
+permeability can give rise to significant changes of transport parameters such
+as permeability and tortuosity. The main parameter controlling the anisotropy
+is $a/L$, being the ratio of the obstacle to system size. Distribution of the
+angle $\alpha$ between the external force and the volumetric fluid stream is
+found to be approximately normal, and the standard deviation of $\alpha$ is
+found to decay with the system size as $(a/L)^{d/2}$, where $d$ is the space
+dimensionality. These properties can be used to estimate both
+anisotropy-related statistical errors in large-scale simulations and the size
+of the representative elementary volume.",0901.3219v1
+2009-02-17,"10-100 TeV cosmic ray anisotropy measured at Baksan EAS ""Carpet"" array","Preliminary results of one year anisotropy measurement in the energy range
+10^{13} -10^{14} eV as a function of energy are presented. The results are
+compared for two methods of data analysis: the standard one with meteo
+correction approach in use and another one so-called ""East minus West"" method.
+Amplitudes and phases of anisotropy for three median energies E = 25 TeV, E =
+75 TeV and E = 120 TeV are reported. Brief consideration of amplitude-phase
+dependence of anisotropy on energy is expounded.",0902.2967v1
+2009-03-20,Quarkonium dissociation in the presence of a small momentum space anisotropy,"We consider the dissociation of heavy quarkonium in a medium close to thermal
+equilibrium but with a small momentum space anisotropy. Dissociation is defined
+to take place when the width of the ground state equals its binding energy. We
+show that if the anisotropic medium is obtained isentropically from the
+equilibrium one, then to first order in the anisotropy parameter the
+dissociation temperature remains unchanged. If, in contrast, the
+non-equilibrium system has a smaller entropy density than the equilibrium one,
+then the dissociation temperature increases with respect to the isotropic case,
+by up to 10% for modest anisotropies.",0903.3467v2
+2009-05-22,Semiclassical suppression of weak anisotropies of a generic Universe,"A semiclassical mechanism which suppresses the weak anisotropies of an
+inhomogeneous cosmological model is developed. In particular, a wave function
+of this Universe having a meaningful probabilistic interpretation is obtained
+that is in agreement with the Copenhagen School. It describes the evolution of
+the anisotropies with respect to the isotropic scale factor which is regarded
+as a semiclassical variable playing an observer-like role. Near the
+cosmological singularity the solution spreads over all values of the
+anisotropies while, when the Universe expands sufficiently, the closed
+Friedmann-Robertson-Walker model appears to be the favorite state.",0905.3695v2
+2009-05-25,Sky maps without anisotropies in the cosmic microwave background are a better fit to WMAP's uncalibrated time ordered data than the official sky maps,"The purpose of this reanalysis of the WMAP uncalibrated time ordered data
+(TOD) was two fold. The first was to reassess the reliability of the detection
+of the anisotropies in the official WMAP sky maps of the cosmic microwave
+background (CMB). The second was to assess the performance of a proposed
+criterion in avoiding systematic error in detecting a signal of interest. The
+criterion was implemented by testing the null hypothesis that the uncalibrated
+TOD was consistent with no anisotropies when WMAP's hourly calibration
+parameters were allowed to vary. It was shown independently for all 20 WMAP
+channels that sky maps with no anisotropies were a better fit to the TOD than
+those from the official analysis. The recently launched Planck satellite should
+help sort out this perplexing result.",0905.3971v3
+2009-06-15,Appearance of classical Mixmaster Universe from the No-Boundary Quantum State,"We investigate the appearance of the classical anisotropic universe from the
+no-boundary quantum state according to the prescription proposed by Hartle,
+Hawking and Hertog. Our model is homogeneous, anisotropic, closed universes
+with a minimally coupled scalar field and cosmological constant. We found that
+there are an ensemble of classical Lorentzian histories with anisotropies and
+experience inflationary expansion at late time, and the probability of
+histories with anisotropies are lower than isotropic histories. Thus the
+no-boundary condition may be able to explain the emergence of our universe. If
+the classical late time histories are extended back, some become singular by
+the existence of initial anisotropies with large accelerations. However we do
+not find any chaotic behavior of anisotropies near the initial singularity.",0906.2616v1
+2009-08-10,CMB anisotropies induced by tensor modes in Massive Gravity,"We study Gravitational Waves (GWs) in the context of Massive Gravity, an
+extension to General Relativity (GR) where the fluctuations of the metric have
+a nonzero mass, and specifically investigate the effect of the tensor modes on
+the Cosmic Microwave Background (CMB) anisotropies. We first study the time
+evolution of the tensor modes in Massive Gravity and show that there is a
+graviton mass limit $m_l=10^{-66}g\sim 10^{-29}cm^{-1}$, so that for masses
+$m\leq m_l$ the tensor perturbations in Massive Gravity are indistinguishable
+from the corresponding ones in GR. Also, we show that short wavelength massive
+modes behave almost indistinguishably from their massless counterparts. Later
+on, we show that massive gravitons with masses within the range $m=
+10^{-27}cm^{-1}$ - $m=10^{-26}cm^{-1}$ would leave a clear signature on the
+lower multipoles ($\ell< 30$) in the CMB anisotropy power spectrum. Hence, our
+results show that CMB anisotropies measurements might be decisive to show
+whether the tensor modes are massive or not.",0908.1360v2
+2009-08-24,Anisotropic microwave conductivity of cuprate superconductors in the presence of CuO chain induced impurities,"The anisotropy in the microwave conductivity of the ortho-II
+YBa$_2$Cu$_3$O$_{6.50}$ is studied within the kinetic energy driven
+superconducting mechanism. The ortho-II YBa$_2$Cu$_3$O$_{6.50}$ is
+characterized by a periodic alternative of filled and empty $\hat{b}$-axis CuO
+chains. By considering the CuO chain induced extended anisotropy impurity
+scattering, the main features of the anisotropy in the microwave conductivity
+of the ortho-II YBa$_2$Cu$_3$O$_{6.50}$ are reproduced based on the nodal
+approximation of the quasiparticle excitations and scattering processes,
+including the intensity and lineshape of the energy and temperature dependence
+of the $\hat{a}$-axis and $\hat{b}$-axis microwave conductivities. Our results
+also confirm that the $\hat{b}$-axis CuO chain induced impurity is the main
+source of the anisotropy.",0908.3355v1
+2009-09-09,Nonequilibrium dynamics of vortex arrest in a finite-temperature Bose-Einstein condensate,"We perform finite-temperature dynamical simulations of the arrest of a
+rotating Bose-Einstein condensate by a fixed trap anisotropy, using a
+Hamiltonian classical-field method. We consider a quasi-two-dimensional
+condensate containing a single vortex in equilibrium with a rotating thermal
+cloud. Introducing an elliptical deformation of the trapping potential leads to
+the loss of angular momentum from the system. We identify the condensate and
+the complementary thermal component of the nonequilibrium field, and compare
+the evolution of their angular momenta and angular velocities. By varying the
+trap anisotropy we alter the relative efficiencies of the vortex-cloud and
+cloud-trap coupling. For strong trap anisotropies the angular momentum of the
+thermal cloud may be entirely depleted before the vortex begins to decay. For
+weak trap anisotropies, the thermal cloud exhibits a long-lived steady state in
+which it rotates at an intermediate angular velocity.",0909.1683v2
+2009-09-14,Interpreting Power Anisotropy Measurements in Plasma Turbulence,"A relationship is derived between power anisotropy and wavevector anisotropy
+in turbulent fluctuations. This can be used to interpret plasma turbulence
+measurements, for example in the solar wind. If fluctuations are anisotropic in
+shape then the ion gyroscale break point in spectra in the directions parallel
+and perpendicular to the magnetic field would not occur at the same frequency,
+and similarly for the electron gyroscale break point. This is an important
+consideration when interpreting solar wind observations in terms of anisotropic
+turbulence theories. Model magnetic field power spectra are presented assuming
+a cascade of critically balanced Alfven waves in the inertial range and kinetic
+Alfven waves in the dissipation range. The variation of power anisotropy with
+scale is compared to existing solar wind measurements and the similarities and
+differences are discussed.",0909.2683v2
+2009-09-30,A solution to the anisotropy problem in bouncing cosmologies,"Bouncing cosmologies are often proposed as alternatives to standard inflation
+for the explanation of the homogeneity and flatness of the universe. In such
+scenarios, the present cosmological expansion is preceded by a contraction
+phase. However, during the contraction, in general the anisotropy of the
+universe grows and eventually leads to a chaotic mixmaster behavior. This would
+either be hard to reconcile with observations or even lead to a singularity
+instead of the bounce. In order to preserve a smooth and isotropic bounce, the
+source for the contraction must have a super-stiff equation of state with
+$P/\rho=w>1$. In this letter we propose a new mechanism to solve the anisotropy
+problem for any low-energy value of $w$ by arguing that high energy physics
+leads to a modification of the equation of state, with the introduction of
+non-linear terms. In such a scenario, the anisotropy is strongly suppressed
+during the high energy phase, allowing for a graceful isotropic bounce, even
+when the low-energy value of $w$ is smaller than unity.",0909.5611v1
+2009-11-17,"Anisotropy of Earth's D"" layer and stacking faults in the MgSiO3 post-perovskite phase","The post-perovskite phase of (Mg,Fe)SiO3 is believed to be the main mineral
+phase of the Earth's lowermost mantle (the D"" layer). Its properties explain
+numerous geophysical observations associated with this layer - for example, the
+D'' discontinuity, its topography and seismic anisotropy within the layer. Here
+we use a novel simulation technique, first-principles metadynamics, to identify
+a family of low-energy polytypic stacking-fault structures intermediate between
+the perovskite and post-perovskite phases. Metadynamics trajectories identify
+plane sliding involving the formation of stacking faults as the most favourable
+pathway for the phase transition, and as a likely mechanism for plastic
+deformation of perovskite and postperovskite. In particular, the predicted slip
+planes are (010) for perovskite (consistent with experiment) and (110) for
+postperovskite (in contrast to the previously expected (010) slip planes).
+Dominant slip planes define the lattice preferred orientation and elastic
+anisotropy of the texture. The (110) slip planes in post-perovskite require a
+much smaller degree of lattice preferred orientation to explain geophysical
+observations of shear-wave anisotropy in the D"" layer.",0911.3185v1
+2009-11-19,Magnetic Anistropy due to the Casimir Effect,"We consider the Casimir interaction between a ferromagnetic and a
+non-magnetic mirror, and show how the Casimir effect gives rise to a magnetic
+anisotropy in the ferromagnetic layer. The anisotropy is out-of-plane if the
+non-magnetic plate is optically isotropic. If the non-magnetic plate shows a
+uniaxial optical anisotropy (with optical axis in the plate plane), we find an
+in-plane magnetic anisotropy. In both cases, the energetically most favorable
+magnetization orientation is given by the competition between polar,
+longitudinal and transverse contributions to the magneto-optical Kerr effect,
+and will therefore depend on the interplate distance. Numerical results will be
+presented for a magnetic plate made out of iron, and non-magnetic plates of
+gold (optically isotropic), quartz, calcite and barium titanate (all uniaxially
+birefringent).",0911.3854v1
+2009-12-09,The detectability of dark matter annihilation with Fermi using the anisotropy energy spectrum of the gamma-ray background,"The energy-dependence of the anisotropy (the anisotropy energy spectrum) of
+the large-scale diffuse gamma-ray background can reveal the presence of
+multiple source populations. Annihilating dark matter in the substructure of
+the Milky Way halo could give rise to a modulation in the anisotropy energy
+spectrum of the diffuse gamma-ray emission measured by Fermi, enabling the
+detection of a dark matter signal. We determine the detectability of a
+dark-matter-induced modulation for scenarios in which unresolved blazars are
+the primary contributor to the measured emission above ~1 GeV and find that in
+some scenarios pair-annihilation cross sections of order the value expected for
+thermal relic dark matter can produce a detectable feature. We anticipate that
+the sensitivity of this technique to specific dark matter models could be
+improved by tailored likelihood analysis methods.",0912.1854v3
+2010-01-04,The single-ion anisotropy in LaFeAsO,"We use Green's function method to study the Heisenberg model of LaFeAsO with
+the striped antiferromagnetic collinear spin structure. In addition to the
+intra-layer spin couplings $J_{1a},J_{1b},J_2$ and the inter-layer coupling
+$J_c$, we further consider the contributions of the single-ion anisotropy
+$J_s$. The analytical expressions for the magnetic phase-transition temperature
+$T_N$ and the spin spectrum gap $\Delta$ are obtained. According to the
+experimental temperature $T_N=138$K and the previous estimations of the
+coupling interactions, we make a further discussion about the magnitude and the
+effects of the single-ion anisotropy $J_s$. We find that the magnitudes of
+$J_s$ and $J_c$ can compete. The dependences of the transition temperature
+$T_N$, the zero-temperature average spin and the spin spectrum gap on the
+single-ion anisotropy are investigated. We find they both increase as $J_s$
+increases. The spin spectrum gap at low temperature $T\to0$ is calculated as a
+function of $J_s$, the result of which is a useful reference for the future
+experimental researches.",1001.0431v1
+2010-01-04,Large Magnetic Susceptibility Anisotropy of Metallic Carbon Nanotubes,"Through magnetic linear dichroism spectroscopy, the magnetic susceptibility
+anisotropy of metallic single-walled carbon nanotubes has been extracted and
+found to be 2-4 times greater than values for semiconducting single-walled
+carbon nanotubes. This large anisotropy is consistent with our calculations and
+can be understood in terms of large orbital paramagnetism of electrons in
+metallic nanotubes arising from the Aharonov-Bohm-phase-induced gap opening in
+a parallel field. We also compare our values with previous work for
+semiconducting nanotubes, which confirm a break from the prediction that the
+magnetic susceptibility anisotropy increases linearly with the diameter.",1001.0524v1
+2010-01-05,Power law behavior for the zigzag transition in a Yukawa cluster,"We provide direct experimental evidence that the one-dimensional (1D) to
+two-dimensional (2D) zigzag transition in a Yukawa cluster exhibits power law
+behavior. Configurations of a six-particle dusty (complex) plasma confined in a
+biharmonic potential well are characterized as the well anisotropy is reduced.
+When the anisotropy is large the particles are in a 1D straight line
+configuration. As the anisotropy is decreased the cluster undergoes a zigzag
+transition to a 2D configuration. The measured dependence of cluster width on
+anisotropy is well described by a power law. A second transition from the
+zigzag to an elliptical configuration is also observed. The results are in very
+good agreement with a model for particles interacting through a Yukawa
+potential.",1001.0753v1
+2010-01-17,Variational Studies of Triangular Heisenberg Antiferromagnet in Magnetic Field,"We present a variational study of the Heisenberg antiferromagnet on the
+spatially anisotropic triangular lattice in magnetic field. First we construct
+a simple yet accurate wavefunction for the 1/3-magnetization plateau uud phase
+on the isotropic lattice. Beginning with this state, we obtain natural
+extensions to nearby commensurate coplanar phases on either side of the
+plateau. The latter occur also for low lattice anisotropy, while the uud state
+extends to much larger anisotropy. Far away from the 1/3 plateau and for
+significant anisotropy, incommensurate states have better energetics, and we
+address competition between coplanar and non-coplanar states in the high field
+regime. For very strong anisotropy, our study is dominated by quasi-1d physics.
+The variational study is supplemented by exact diagonalization calculations
+which provide a reference for testing the energetics of our trial wavefunctions
+as well as helping to identify candidate phases.",1001.2863v2
+2010-03-19,Anisotropy of the superconducting state parameters and intrinsic pinning in low-level Pr-doped YBa2Cu3O(7-delta) single crystals,"The influence of low-level Pr substitution in Y1-xPrxBa2Cu3O(7-delta) single
+crystals on the anisotropy of the superconducting state parameters was
+investigated by torque magnetometry in magnetic fields of up to 9 T. An
+averaged anisotropy parameter, \gamma, of 7.4 was found and no influence of the
+Pr ion concentration on \gamma was observed up to a Pr content of 2.4%. A
+pronounced maximum at angles between 0.5 and 1 degree out of the ab-plane was
+observed in all crystals in the irreversible angular dependence of the torque.
+This maximum is attributed to intrinsic pinning associated with kinked
+vortices. The variation of the irreversible torque with the substitution level
+indicates the influence of the Pr content on pinning within the CuO2 planes,
+even though the anisotropy of the superconducting state parameters is not
+affected.",1003.3793v1
+2010-04-27,Nonequilibrium relaxation study of the anisotropic antiferromagnetic Heisenberg model on the triangular lattice,"Effect of exchange anisotropy on the relaxation time of spin and vector
+chirality is studied for the antiferromagnetic classical Heisenberg model on
+the triangular lattice by using the nonequilibrium relaxation Monte Carlo
+method. We identify the Berezinskii-Kosterlitz-Thouless (BKT) transition and
+the chiral transition in a wide range of the anisotropy, even for very small
+anisotropy of $\sim$ 0.01%. As the anisotropy decreases, both the critical
+temperatures steeply decrease, while the BKT critical region becomes
+divergently wide. We elucidate a sharp ""V shape"" of the phase diagram around
+the isotropic Heisenberg point, which suggests that the isotropic case is
+exceptionally singular and the associated Z vortex transition will be isolated
+from the BKT and chiral transitions. We discuss the relevance of our results to
+peculiar behavior of the spin relaxation time observed experimentally in
+triangular antiferromagnets.",1004.4927v1
+2010-06-18,Magnetic anisotropy in thin films of Prussian blue analogues,"The magnetic anisotropy of thin (~ 200 nm) and thick (~ 2 $\mu$m) films and
+of polycrystalline (diameters ~ 60 nm) powders of the Prussian blue analogue
+Rb$_{0.7}$Ni$_{4.0}$[Cr(CN)$_6$]$_{2.9} \cdot n$H$_2$O, a ferromagnetic
+material with $T_c \sim 70$ K, have been investigated by magnetization, ESR at
+50 GHz and 116 GHz, and variable-temperature x-ray diffraction (XRD). The
+origin of the anisotropic magnetic response cannot be attributed to the direct
+influence of the solid support, but the film growth protocol that preserves an
+organized two-dimensional film is important. In addition, the anisotropy does
+not arise from an anisotropic g-tensor nor from magneto-lattice variations
+above and below $T_c$. By considering effects due to magnetic domains and
+demagnetization factors, the analysis provides reasonable descriptions of the
+low and high field data, thereby identifying the origin of the magnetic
+anisotropy.",1006.3801v2
+2010-07-19,Evidence for a temperature dependent anisotropy of the superconducting state parameters in underdoped SmBa2Cu3Ox,"The temperature dependence of the anisotropy of the superconducting state
+parameters, {\gamma}, was studied by torque magnetometry for the high
+temperature superconductor SmBa2Cu3Ox in magnetic fields of up to 9 T. The
+measurements were performed on four underdoped single crystals with oxygen
+contents corresponding to Tc's varying from 42.8 to 63.6 K. The anisotropy was
+found to be strongly temperature dependent, while only a weak dependence on the
+magnetic field was observed. No evidence for a field dependent superfluid
+density was found. Possible origins of the temperature dependence of the
+anisotropy are discussed.",1007.3152v1
+2010-09-14,Anisotropy-axis orientation effect on the magnetization of γ-Fe2O3 frozen ferrofluid,"The effect of magnetic anisotropy-axis alignment on the superparamagnetic
+(SPM) and superspin glass (SSG) states in a frozen ferrofluid has been
+investigated. The ferrofluid studied here consists of maghemite nanoparticles
+(\gamma-Fe2O3, mean diameter = 8.6 nm) dispersed in glycerine at a volume
+fraction of ~15%. In the high temperature SPM state, the magnetization of
+aligned ferrofluid increased by a factor varying between 2 and 4 with respect
+to that in the randomly oriented state. The negative interaction energy
+obtained from the Curie-Weiss fit to the high temperature susceptibility in the
+SPM states as well as the SSG phase onset temperature determined from the
+linear magnetization curves were found to be rather insensitive to the
+anisotropy axis alignment. The low temperature aging behaviour, explored via
+""zero-field cooled magnetization"" (ZFCM) relaxation measurements, however, show
+distinct difference in the aging dynamics in the anisotropy-axis aligned and
+randomly oriented SSG states.",1009.2610v1
+2010-10-01,"Surface morphology and magnetic anisotropy in (Ga,Mn)As","Atomic Force Microscopy and Grazing incidence X-ray diffraction measurements
+have revealed the presence of ripples aligned along the $[1\bar{1}0]$ direction
+on the surface of (Ga,Mn)As layers grown on GaAs(001) substrates and buffer
+layers, with periodicity of about 50 nm in all samples that have been studied.
+These samples show the strong symmetry breaking uniaxial magnetic anisotropy
+normally observed in such materials. We observe a clear correlation between the
+amplitude of the surface ripples and the strength of the uniaxial magnetic
+anisotropy component suggesting that these ripples might be the source of such
+anisotropy.",1010.0112v2
+2010-11-24,Impact of anisotropy on vortex clusters and their dynamics,"We investigate the effects of anisotropy on the stability and dynamics of
+vortex cluster states which arise in Bose-Einstein condensates. Sufficiently
+strong anisotropies are shown to stabilize states with arbitrary numbers of
+vortices that are highly unstable in the isotropic limit. Conversely,
+anisotropy can be used to destabilize states which are stable in the isotropic
+limit. Near the linear limit, we identify the bifurcations of vortex states
+including their emergence from linear eigenstates, while in the strongly
+nonlinear limit, a particle-like description of the dynamics of the vortices in
+the anisotropic trap is developed. Both are in very good agreement with
+numerical results. Collective modes of stabilized many vortex cluster states
+are demonstrated.",1011.5350v1
+2010-12-27,Transport properties and anisotropy of Rb0.8Fe2Se2 single crystals,"Single crystals of Rb{0.8}Fe2Se2 are successfully synthesized with the
+superconducting transition temperatures T_c{onset}= 31 K and T_c{zero}= 28 K. A
+clear anomaly of resistivity was observed in the normal state at about 150 K,
+as found in a similar system KxFe2Se2. The upper critical field has been
+determined with the magnetic field along ab-plane and c-axis, yielding an
+anisotropy of about 3.5. The angle dependent resistivity measured below T_c
+allow a perfect scaling feature based on the anisotropic Ginzburg-Landau
+theory, leading to a consistent value of the anisotropy which decreases from
+about 3.6 at around T_c to 2.9 at 27 K. Comparing to the anisotropy determined
+for Ba0.6K0.4Fe2As2 and Ba(Fe0.92Co0.08)2As2 using the same method, we find
+that the present sample is more anisotropic and the Fermi surfaces with
+stronger two dimensional characters are expected.",1012.5637v3
+2011-02-15,Magnetic torque study of the temperature dependent anisotropy parameter in overdoped superconducting single-crystal YBa_2Cu_3O_7,"An overdoped YBa2Cu3O7 single crystal was studied by SQUID and torque
+magnetometry in order to investigate the temperature dependence of the
+anisotropy parameter close to the transition temperature T_c (0.87 T_c < T <
+T_c). Angle dependent torque measurements were performed and analyzed with the
+widely used Kogan model [Phys. Rev. B 38, 7049 (1988)] as well as with an
+extended model by Hao and Clem [Phys. Rev. Lett. 67, 2371 (1991)], taking into
+account the influence of the vortex cores on the magnetization. Both approaches
+yield similar results, with an out-of-plane anisotropy parameter around 6.5
+which slightly increases with decreasing temperature, and a temperature
+independent in-plane anisotropy parameter gamma_ab}= 1.12(5).",1102.2990v3
+2011-02-24,The role of magnetic anisotropy in spin filter junctions,"We have fabricated oxide based spin filter junctions in which we demonstrate
+that magnetic anisotropy can be used to tune the transport behavior of spin
+filter junctions. Until recently, spin filters have been largely comprised of
+polycrystalline materials where the spin filter barrier layer and one of the
+electrodes are ferromagnetic. These spin filter junctions have relied on the
+weak magnetic coupling between one ferromagnetic electrode and a barrier layer
+or the insertion of a nonmagnetic insulating layer in between the spin filter
+barrier and electrode. We have demonstrated spin filtering behavior in
+La0.7Sr0.3MnO3/chromite/Fe3O4 junctions without nonmagnetic spacer layers where
+the interface anisotropy plays a significant role in determining transport
+behavior. Detailed studies of chemical and magnetic structure at the interfaces
+indicate that abrupt changes in magnetic anisotropy across the
+non-isostructural interface is the cause of the significant suppression of
+junction magnetoresistance in junctions with MnCr2O4 barrier layers.",1102.4978v1
+2011-03-04,Temporal response to harmonic driving in electroconvection,"The temporal evolution of the spatially periodic electroconvection (EC)
+patterns has been studied within the period of the driving ac voltage by
+monitoring the light intensity diffracted from the pattern. Measurements have
+been carried out on a variety of nematic systems, including those with negative
+dielectric and positive conductivity anisotropy, exhibiting ""standard EC""
+(s-EC), those with both anisotropies negative exhibiting ""non-standard EC""
+(ns-EC), as well as those with the two anisotropies positive. Theoretical
+predictions have been confirmed for stationary s-EC and ns-EC patterns.
+Transitions with Hopf bifurcation have also been studied. While traveling had
+no effect on the temporal evolution of dielectric s-EC, traveling conductive
+s-EC and ns-EC patterns exhibited a substantially altered temporal behavior
+with a dependence on the Hopf frequency. It has also been shown that in
+nematics with both anisotropies positive, the pattern develops and decays
+within an interval much shorter than the period, even at relatively large
+driving frequencies.",1103.0898v1
+2011-03-31,Anisotropy of magnetic emulsions induced by magnetic and electric fields,"The anisotropy of magnetic emulsions induced by simultaneously acting
+electric and magnetic fields is theoretically and experimentally investigated.
+Due to the anisotropy, the electric conductivity and magnetic permeability of a
+magnetic emulsion are no longer scalar coefficients, but are tensors. The
+electric conductivity and magnetic permeability tensors of sufficiently diluted
+emulsions in sufficiently weak electric and magnetic fields are found as
+functions of the electric and magnetic intensity vectors. The theoretically
+predicted induced anisotropy was verified experimentally. The experimental data
+are analyzed and compared with theoretical predictions. The results of the
+analysis and comparison are discussed.",1103.6251v2
+2011-05-02,Quantifying the anisotropy in the infrared emission of powerful AGN,"We use restframe near- and mid-IR data of an isotropically selected sample of
+quasars and radio galaxies at 1.0 \leq z \leq 1.4, which have been published
+previously, to study the wavelength-dependent anisotropy of the IR emission.
+For that we build average SEDs of the quasar subsample (= type 1 AGN) and radio
+galaxies (= type 2 AGN) from ~1-17 {\mu}m and plot the ratio of both average
+samples. From 2 to 8 {\mu}m restframe wavelength the ratio gradually decreases
+from 20 to 2 with values around 3 in the 10{\mu}m silicate feature. Longward of
+12{\mu}m the ratio decreases further and shows some high degree of isotropy at
+15 {\mu}m (ratio ~1.4). The results are consistent with upper limits derived
+from the X-ray/mid-IR correlation of local Seyfert galaxies. We find that the
+anisotropy in our high-luminosity radio-loud sample is smaller than in
+radio-quiet lower-luminosity AGN which may be interpreted in the framework of a
+receding torus model with luminosity-dependent obscuration properties. It is
+also shown that the relatively small degree of anisotropy is consistent with
+clumpy torus models.",1105.0429v1
+2011-05-09,Properties of magnetic nanodots with perpendicular anisotropy,"Nanodots with magnetic vortices have many potential applications, such as
+magnetic memories (VRAMs) and spin transfer nano-oscillators (STNOs). Adding a
+perpendicular anisotropy term to the magnetic energy of the nanodot it becomes
+possible to tune the vortex core properties. This can be obtained, e.g., in Co
+nanodots by varying the thickness of the Co layer in a Co/Pt stack. Here we
+discuss the spin configuration of circular and elliptical nanodots for
+different perpendicular anisotropies; we show for nanodisks that micromagnetic
+simulations and analytical results agree. Increasing the perpendicular
+anisotropy, the vortex core radii increase, the phase diagrams are modified and
+new configurations appear; the knowledge of these phase diagrams is relevant
+for the choice of optimum nanodot dimensions for applications. MFM measurements
+on Co/Pt multilayers confirm the trend of the vortex core diameters with
+varying Co layer thicknesses.",1105.1813v1
+2011-06-03,Origin of in-plane uniaxial magnetic anisotropy in CoFeB amorphous ferromagnetic thin-films,"Describing the origin of uniaxial magnetic anisotropy (UMA) is generally
+problematic in systems other than single crystals. We demonstrate an in-plane
+UMA in amorphous CoFeB films on GaAs(001) which has the expected symmetry of
+the interface anisotropy in ferromagnetic films on GaAs(001), but strength
+which is independent of, rather than in inverse proportion to, the film
+thickness. We show that this volume UMA is consistent with a bond-orientational
+anisotropy, which propagates the interface-induced UMA through the thickness of
+the amorphous film. It is explained how, in general, this mechanism may
+describe the origin of in-plane UMAs in amorphous ferromagnetic films.",1106.0606v1
+2011-06-07,Evolution of curvature and anisotropy near a nonsingular bounce,"We consider bouncing cosmologies in which an ekpyrotic contraction phase with
+w >> 1 is followed by a bouncing phase with w < -1 that violates the null
+energy condition. The bouncing phase, induced by ghost condensation, is
+designed to produce a classically nonsingular bounce at a finite value of the
+scale factor. We show that the initial curvature and anisotropy, though diluted
+during the ekpyrotic phase, grow back exponentially during the bouncing phase.
+Moreover, curvature perturbations and anisotropy are generated by quantum
+fluctuations during the ekpyrotic phase. In the bouncing phase, however, an
+adiabatic curvature perturbation grows to dominate and contributes a blue
+spectrum that spoils the scale-invariance. Meanwhile, a scalar shear
+perturbation grows nonlinear and creates an overwhelming anisotropy that
+disrupts the nonsingular bounce altogether.",1106.1416v2
+2011-06-17,Electromagnetic signatures of a strongly coupled anisotropic plasma,"In heavy-ion collisions, quark-gluon plasma is likely to be produced with
+sizable initial pressure anisotropy, which may leave an imprint on
+electromagnetic observables. In order to model a strongly coupled anisotropic
+plasma, we use the AdS/CFT correspondence to calculate the current-current
+correlator of a weakly gauged U(1) subgroup of R symmetry in an N=4
+super-Yang-Mills plasma with a (temporarily) fixed anisotropy. The dual
+geometry, obtained previously by Janik and Witaszczyk, contains a naked
+singularity which however permits purely infalling boundary conditions and
+therefore the usual definition of a retarded correlator. We obtain numerical
+results for the cases of wave vector parallel and orthogonal to the direction
+of anisotropy, and we compare with previous isotropic results. In the
+(unphysical) limit of vanishing frequency (infinite time) we obtain a vanishing
+DC conductivity for any amount of anisotropy, but the anisotropic AC
+conductivities smoothly approach the isotropic case in the limit of high
+frequencies. We also discuss hard photon production from an anisotropic plasma
+and compare with existing hard-loop resummed calculations.",1106.3539v3
+2011-07-29,$Bi_2Te_3$: Implications of the rhombohedral k-space texture on the evaluation of the in-plane/out-of-plane conductivity anisotropy,"Different computational scheme for calculating surface integrals in
+anisotropic Brillouin zones are compared. The example of the transport
+distribution function (plasma frequency) of the thermoelectric Material \BiTe
+near the band edges will be discussed. The layered structure of the material
+together with the rhombohedral symmetry causes a strong anisotropy of the
+transport distribution function for the directions in the basal (in-plane) and
+perpendicular to the basal plane (out-of-plane). It is shown that a thorough
+reciprocal space integration is necessary to reproduce the
+in-plane/out-of-plane anisotropy. A quantitative comparison can be made at the
+band edges, where the transport anisotropy is given in terms of the anisotropic
+mass tensor.",1108.0023v1
+2011-07-30,Spiraling elliptic solitons in nonlocal nonlinear media without anisotropy,"The optical spatial solitons with ellipse-shaped spots have generally been
+considered to be a result of either linear or nonlinear anisotropy. In this
+paper, we introduce a class of spiraling elliptic solitons in the nonlocal
+nonlinear media without both linear and nonlinear anisotropy. The spiraling
+elliptic solitons carry the orbital angular momentum, which plays a key role in
+the formation of such solitons, and are stable for any degree of nonlocality
+except the local case when the response function of the material is Gaussian
+function. The formation of such solitons can be attributable to the effective
+anisotropic diffraction (linear anisotropy) resulting from the orbital angular
+momentum. Our variational analytical result is confirmed by direct numerical
+simulation of the nonlocal nonlinear Schrodinger equation.",1108.0055v1
+2011-08-17,Magnetic properties of Mn impurities on GaAs (110) surfaces,"We present a computational study of individual and pairs of substitutional Mn
+impurities on the (110) surface of GaAs samples based on density functional
+theory. We focus on the anisotropy properties of these magnetic centers and
+their dependence on on-site correlations, spin-orbit interaction and
+surface-induced symmetry-breaking effects. For a Mn impurity on the surface,
+the associated acceptor-hole wavefunction tends to be more localized around the
+Mn than for an impurity in bulk GaAs. The magnetic anisotropy energy for
+isolated Mn impurities is of the order of 1 meV, and can be related to the
+anisotropy of the orbital magnetic moment of the Mn acceptor hole. Typically Mn
+pairs have their spin magnetic moments parallel aligned, with an exchange
+energy that strongly depends on the pair orientation on the surface. The spin
+magnetic moment and exchange energies for these magnetic entities are not
+significantly modified by the spin-orbit interaction, but are more sensitive to
+on-site correlations. Correlations in general reduce the magnetic anisotropy
+for most of the ferromagnetic Mn pairs.",1108.3440v2
+2011-08-29,Anisotropy of the coherence length from critical currents in the stoichiometric superconductor LiFeAs,"Miniature Hall-probe arrays were used to measure the critical current
+densities for the three main directions of vortex motion in the stoichiometric
+LiFeAs superconductor. These correspond to vortices oriented along the c-axis
+moving parallel to the ab-plane, and to vortices in the ab-plane moving
+perpendicular to, and within the plane, respectively. The measurements were
+carried out in the low-field regime of strong vortex pinning, in which the
+critical current anisotropy is solely determined by the coherence length
+anisotropy parameter, {\epsilon}_{\xi}. This allows extraction of
+{\epsilon}_{\xi} at magnetic fields far below the upper critical field B_c2. We
+find that increasing magnetic field decreases the anisotropy of the coherence
+length.",1108.5583v3
+2011-09-01,Electronic structure and transport anisotropy of Bi2Te3 and Sb2Te3,"On the basis of detailed ab initio studies the influence of strain on the
+anisotropy of the transport distribution of the thermoelectrics Bi$_2$Te$_3$
+and Sb$_2$Te$_3$ was investigated. Both tellurides were studied in their own,
+as well as in their co-partners lattice structure to gain insight to the
+electrical transport in epitaxial heterostructures composed of both materials.
+It is shown, that the anisotropy of the transport distribution overestimates
+the experimental findings for Bi$_2$Te$_3$, implying anisotropic scattering
+effects. An increase of the in-plane lattice constant leads to an enhancement
+of the transport anisotropy for $p$-doping, whereas the opposite occurs for
+$n$-doping. The recent findings and special features of the transport
+distribution are discussed in detail in relation to the topology of the band
+structures.",1109.0186v1
+2011-09-05,Direction Dependence of the Deceleration Parameter,"In this paper we study the possibly existing anisotropy in the acceleration
+expansion by use of the full sample of Union2 data. Using the hemisphere
+comparison method to search for a preferred direction, we take the deceleration
+parameter q0 as the diagnostic to quantify the anisotropy level in the wCDM
+model. We find that the maximum accelerating expansion direction is
+$(l,b)=(314_{+20^{\circ}}^{\circ-13^{\circ}},28_{+11^{\circ}}^{\circ-33^{\circ}})$,with
+the maximum anisotropy level of $\delta
+q_{0,max}/\bar{q}_0=0.79_{+0.27}^{-0.28}$, and that the anisotropy is more
+prominent when only low redshift data ($z\leq0.2$) are used. We also discuss
+this issue in the $CPL$ parameterized model, showing a similar result.",1109.0941v6
+2011-09-24,Interface-Roughening Phase Diagram of the Three-Dimensional Ising Model for All Interaction Anisotropies from Hard-Spin Mean-Field Theory,"The roughening phase diagram of the d=3 Ising model with uniaxially
+anisotropic interactions is calculated for the entire range of anisotropy, from
+decoupled planes to the isotropic model to the solid-on-solid model, using
+hard-spin mean-field theory. The phase diagram contains the line of ordering
+phase transitions and, at lower temperatures, the line of roughening phase
+transitions, where the interface between ordered domains roughens. Upon
+increasing the anisotropy, roughening transition temperatures settle after the
+isotropic case, whereas the ordering transition temperature increases to
+infinity. The calculation is repeated for the d=2 Ising model for the full
+range of anisotropy, yielding no roughening transition.",1109.5294v2
+2011-10-03,Phase transitions in spin-orbital models with spin-space anisotropies for iron-pnictides: A study through Monte Carlo simulations,"The common phase diagrams of superconducting iron pnictides show interesting
+material specificities in the structural and magnetic phase transitions. In
+some cases the two transitions are separate and second order, while in others
+they appear to happen concomitantly as a single first order transition. We
+explore these differences using Monte Carlo simulations of a two-dimensional
+Hamiltonian with coupled Heisenberg-spin and Ising-orbital degrees of freedom.
+In this spin-orbital model, the finite-temperature orbital-ordering transition
+results in a tetragonal-to-orthorhombic symmetry reduction and is associated
+with the structural transition in the iron-pnictide materials. With a zero or
+very small spin space anisotropy, the magnetic transition separates from the
+orbital one in temperature, and the orbital transition is found to be in the
+Ising universality class. With increasing anisotropy, the two transitions
+rapidly merge together and tend to become weakly first order. We also study the
+case of a single-ion anisotropy and propose that the preferred spin-orientation
+along the antiferromagnetic direction in these materials is driven by orbital
+order.",1110.0434v2
+2011-10-04,Trans-Alfvenic Motions in the Taurus Molecular Cloud,"Magnetically aligned velocity anisotropy over varying physical conditions and
+environments within the Taurus Molecular Cloud is evaluated from analysis of
+wide field spectroscopic imaging of 12CO and 13CO J=1-0 emission. Such
+anisotropy is a result of MHD turbulence in the strong magnetic field regime
+and provides an indirect measure of the role of magnetic fields upon the gas.
+Velocity anisotropy aligned with the local, projected mean magnetic field
+direction is limited to fields with low surface brightness 12CO emission
+corresponding to regions of low visual extinction and presumably, low gas
+volume density. The more optically thin 13CO J=1-0 emission shows little
+evidence for velocity anisotropy. We compare our results with computational
+simulations with varying degrees of magnetic field strength and Alfvenic Mach
+numbers. In the diffuse, molecular envelope of the cloud, a strong magnetic
+field and sub-Alfvenic turbulent motions are inferred. Super-Alfvenic motions
+are present within the high column density filaments of the Taurus cloud. From
+this trans-Alfvenic flow, we constrain the scaling exponent, kappa, of the
+magnetic field density relation (B ~ n^kappa) to be near zero as expected for
+ambipolar diffusion or material loading of magnetic flux tubes.",1110.0808v1
+2011-10-10,Observation of Anisotropy in the Arrival Direction Distribution of Cosmic Rays above TeV Energies with Icecube,"Between May 2009 and May 2010, the IceCube neutrino detector recorded 32
+billion of atmospheric muons generated in air showers produced by cosmic rays
+in the TeV energy range. With such high statistics sample it is possible to
+observe, for the first time in the southern hemisphere, an energy dependence in
+the Galactic cosmic ray anisotropy up to a few hundred TeV. This study shows
+that the same large-scale anisotropy observed at median energies around 20 TeV
+is not present at 400 TeV; the anisotropy observed at 400 TeV shows substantial
+differences with respect to that at lower energy. In addition to the
+large-scale features observed at 20 TeV in the form of strong dipole and
+quadrupole moments, the data include several localized regions of excess and
+deficit on scales between 10{\degree} to 30{\degree}. The features observed at
+both large and small scale are statistically significant, but their origin is
+currently unknown.",1110.2079v1
+2011-10-13,Nonaxisymmetric Anisotropy of Solar Wind Turbulence as a Direct Test for the Models of Magnetohydrodynamic Tubulence,"Single point spacecraft observations of the turbulent solar wind flow exhibit
+a characteristic nonaxisymmetric anisotropy that depends sensitively on the
+perpendicular power spectral exponent. For the first time we use this
+nonaxisymmetric anisotropy as a function of wave vector direction to test
+models of magnetohydrodynamic (MHD) turbulence. Using Ulysses magnetic field
+observations in the fast, quiet polar solar wind we find that the
+Goldreich-Sridhar model of MHD turbulence is not consistent with the observed
+anisotropy, whereas the observations are well reproduced by the ""Slab + 2D""
+model. The Golderich-Sridhar model alone can not account for the observations
+unless an additional component is also present.",1110.2932v1
+2011-10-25,"Magnetoresistance of individual ferromagnetic GaAs/(Ga,Mn)As core-shell nanowires","We investigate, angle dependent, the magnetoresistance (MR) of individual
+self-assembled ferromagnetic GaAs/(Ga,Mn)As core-shell nanowires at cryogenic
+temperatures. The shape of the MR traces and the observed strong anisotropies
+in transport can be ascribed to the interplay of the negative magnetoresistance
+effect and a strong uniaxial anisotropy with the magnetic easy direction
+pointing along the wire axis. The magnetoresistance can be well described by a
+quantitative analysis based on the concept of the effective magnetic field,
+usually used to describe ferromagnetic resonance phenomena. The nanowires we
+investigate exhibit a uniaxial anisotropy which is approximately 5 times larger
+than the strain induced anisotropy observed in lithographically prepared
+(Ga,Mn)As stripes.",1110.5507v1
+2011-11-03,Doping - dependent superconducting gap anisotropy in the two-dimensional 10-3-8 pnictide Ca$_{10}$(Pt$_3$As$_8$)[(Fe$_{1-x}$Pt$_{x}$)$_2$As$_2$]$_5$,"The characteristic features of
+Ca$_{10}$(Pt$_3$As$_8$)[(Fe$_{1-x}$Pt$_x$)$_2$As$_2$]$_5$ (""10-3-8"")
+superconductor are relatively high anisotropy and a clear separation of
+superconductivity and structural/magnetic transitions, which allows studying
+the superconducting gap without complications due to the coexisting order
+parameters. The London penetration depth, measured in underdoped single
+crystals of 10-3-8 ($x =$ 0.028, 0.041, 0.042, and 0.097), shows behavior
+remarkably similar to other Fe-based superconductors, exhibiting robust
+power-law, $\Delta \lambda(T) = A T^n$. The exponent $n$ decreases from 2.36
+($x =$ 0.097, close to optimal doping) to 1.7 ($x =$ 0.028, a heavily
+underdoped composition), suggesting that the superconducting gap becomes more
+anisotropic at the dome edge. A similar trend is found in low-anisotropy
+superconductors based on BaFe$_2$As$_2$ (""122""), implying that it is an
+intrinsic property of superconductivity in iron pnictides, unrelated to the
+coexistence of magnetic order and superconductivity or the anisotropy of the
+normal state. Overall this doping dependence is consistent with $s_{\pm}$
+pairing competing with intra-band repulsion.",1111.1003v1
+2011-11-11,Temperature anisotropy and differential streaming of solar wind ions -- Correlations with transverse fluctuations,"We study correlations of the temperature ratio (which is an indicator for
+perpendicular ion heating) and the differential flow of the alpha particles
+with the power of transverse fluctuations that have wave numbers between 0.01
+and 0.1 (normalized to $k_p=1/l_p$, where $l_p$ is the proton inertial length).
+We found that both the normalized differential ion speed, $V_{\alpha
+p}/V_\mathrm{A}$ (where $V_\mathrm{A}$ is the Alfv\'en speed) and the proton
+temperature anisotropy, $T_{\perp p}/T_{\parallel p}$, increase when the
+relative wave power is growing. Furthermore, if the normalized differential ion
+speed stays below 0.5, the alpha-particle temperature anisotropy, $T_{\perp
+\alpha}/T_{\parallel \alpha}$, correlates positively with the relative power of
+the transverse fluctuations. However, if $V_{\alpha p}/V_\mathrm{A}$ is higher
+than 0.6, then the alpha-particle temperature anisotropy tends to become lower
+and attain even values below unity despite the presence of transverse
+fluctuations of relatively high amplitudes. Our findings appear to be
+consistent with the expectations from kinetic theory for the resonant
+interaction of the ions with Alfv\'en/ion-cyclotron waves and the resulting
+wave dissipation.",1111.2724v1
+2011-11-13,Anisotropy of TeV Cosmic Rays and the Outer Heliospheric Boundaries,"Cosmic rays in the energy range from about 10's GeV to several 100's TeV are
+observed on Earth with an energy-dependent anisotropy of order 0.01-0.1%, and a
+consistent topology that appears to significantly change at higher energy. The
+nearest and most recent galactic cosmic ray sources might stochastically
+dominate the observation and possibly explain a change in orientation of the
+anisotropy as a function of energy. However, the diffusion approximation is not
+able to explain its non-dipolar structure and, in particular, the significant
+contribution of small angular scale features. Particle propagation within the
+mean free path in the local interstellar medium might have a major role in
+determining the properties of galactic cosmic rays, such as their arrival
+distribution. In particular, scattering on perturbations induced in the local
+interstellar magnetic field by the heliosphere wake, may cause a
+re-distribution of anisotropic cosmic rays below about 100 TeV toward the
+direction of the elongated heliotail and of the local interstellar magnetic
+field in the outer heliosphere. Such scattering processes are considered
+responsible of the observed TeV cosmic ray global anisotropy and its fine
+angular structure.",1111.3075v2
+2011-11-17,Field-induced Magnetic Transition in Cobalt-Ferrite,"We present magnetostriction and magnetization measurements of a cobalt
+ferrite Co0.8Fe2.2O4 single crystal. We observe unusual behaviour in the
+magnetic hard axis of the single crystal which manifests in a jump of the
+magnetization curve at a critical field. This first order magnetization process
+(FOMP) which is explained as an anisotropy driven transition is visible at
+temperatures lower than 150 K. By analyzing the anisotropy constants we found
+that the higher order anisotropy constant K2 dominates the anisotropy energy.
+In the magnetostriction measurements the FOMP is clearly visible as a huge jump
+in the [111] direction, which can be explained by means of a geometric model.",1111.4027v2
+2011-12-03,Observation of CR Anisotropy with ARGO-YBJ,"The measurement of the anisotropies of cosmic ray arrival direction provides
+important informations on the propagation mechanisms and on the identification
+of their sources. In this paper we report the observation of anisotropy regions
+at different angular scales. In particular, the observation of a possible
+anisotropy on scales between $\sim$ 10 $^{\circ}$ and $\sim$ 30 $^{\circ}$
+suggests the presence of unknown features of the magnetic fields the charged
+cosmic rays propagate through, as well as potential contributions of nearby
+sources to the total flux of cosmic rays. Evidence of new weaker few-degree
+excesses throughout the sky region $195^{\circ}\leq$ R.A. $\leq 315^{\circ}$ is
+reported for the first time.",1112.0666v2
+2011-12-11,Anisotropies in the cosmic radiation observed with ARGO-YBJ,"Important informations on the origin and the propagation mechanisms of cosmic
+rays may be provided by the measurement of the anisotropies of their arrival
+direction. In this paper the observation of anisotropy regions at different
+angular scales is reported. In particular, the observation of a possible
+anisotropy on scales between $\sim10^{\circ}$ and $\sim30^{\circ}$ may be a
+key-detection for speculations on the presence of unknown features of the
+magnetic fields the charged cosmic rays propagate through, as well as to
+potential contributions of nearby sources to the total flux of cosmic rays.
+Evidence of new weaker few-degree excesses throughout the sky region
+$195^{\circ}\leq$ R.A. $\leq 315^{\circ}$ is also reported.",1112.2375v1
+2011-12-22,Initial state anisotropies and their uncertainties in ultrarelativistic heavy-ion collisions from the Monte Carlo Glauber model,"In hydrodynamical modeling of heavy-ion collisions, the initial-state spatial
+anisotropies are translated into momentum anisotropies of the final-state
+particle distributions. Thus, understanding the origin of the initial-state
+anisotropies and their uncertainties is important before extracting specific
+QCD matter properties, such as viscosity, from the experimental data. In this
+work we review the wounded nucleon approach based on the Monte Carlo Glauber
+model, charting in particular the uncertainties arising from modeling of the
+nucleon-nucleon interactions between the colliding nucleon pairs and
+nucleon-nucleon correlations inside the colliding nuclei. We discuss the
+differences between the black disk model and a probabilistic profile function
+approach for the inelastic nucleon-nucleon interactions, and investigate the
+influence of initial-state correlations using state-of-the-art modeling of
+these.",1112.5306v2
+2011-12-26,Different types of the dimensional crossover in the quasi-one-dimensional spinless fermion systems,"It is known that many-body correlations qualitatively modify the properties
+of a one-dimensional metal. However, for a quasi-one-dimensional metal these
+correlations are suppressed, at least partially. We study conditions under
+which the one-dimensional effects significantly influence the dimensional
+crossover of a quasi-one-dimensional metal. It is proved (i) that even a system
+with very high anisotropy of the single-particle hopping might behave on both
+sides of the crossover as an ordinary weakly non-ideal Fermi gas. Further, (ii)
+to demonstrate well-developed signatures of one-dimensional correlations the
+system must have extremely (exponentially) high anisotropy. Between cases (i)
+and (ii) an intermediate regime lies: (iii) the one-dimensional phenomena
+affect the two-particle susceptibilities, but do not reveal themselves in
+single-particle quantities. Unlike the normal state properties, (iv) the
+ordering transition is always very sensitive to the anisotropy: the mean field
+theory quickly becomes invalid as the anisotropy increases. An expression for
+the transition temperature is derived. The attributes (i-iv) are used to
+classify the weakly interacting quasi-one-dimensional fermion systems.",1112.5852v1
+2012-01-10,Effect of anisotropy on small magnetic clusters,"The effect of dipolar interaction and local uniaxial anisotropy on the
+magnetic response of small spin clusters where spins are located on the
+vertices of icosahedron, cuboctahedron, tetrahedron and square geometry have
+been investigated. We consider the ferromagnetic and antiferromagnetic spin-1/2
+and spin-1 Heisenberg model with uniaxial anisotropy and dipolar interaction
+and apply numerical exact diagonalization technique in order to study the
+influence of frustration and anisotropy on the ground state properties of the
+spin-clusters. The ground state magnetization, spin-spin correlation and
+several thermodynamic quantities such as entropy and specific heat are
+calculated as a function of temperature and magnetic field.",1201.2088v1
+2012-01-13,Strong single-ion anisotropy and anisotropic interactions of magnetic adatoms induced by topological surface states,"The nature of the magnetism brought about by Fe adatoms on the surface of the
+topological insulator Bi2Se3 was examined in terms of density functional
+calculations. The Fe adatoms exhibit strong easy-axis magnetic anisotropy in
+the dilute adsorption limit due to the topological surface states (TSS). The
+spin exchange J between the Fe adatoms follows a Ruderman-Kittel-Kasuya-Yosida
+(RKKY) behavior with substantial anisotropy, and the Dzyaloshinskii-Moriya (DM)
+interaction between them is quite strong with |D/J|~0.3 under the mediation by
+the TSS, and can be further raised to ~0.6 by an external electric field. The
+apparent single-ion anisotropy of a Fe adatom is indispensable in determining
+the spin orientation.",1201.2857v1
+2012-01-20,Probing the Intergalactic Magnetic Field with the Anisotropy of the Extragalactic Gamma-ray Background,"The intergalactic magnetic field (IGMF) may leave an imprint on the angular
+anisotropy of the extragalactic gamma-ray background through its effect on
+electromagnetic cascades triggered by interactions between very high energy
+photons and the extragalactic background light. A strong IGMF will deflect
+secondary particles produced in these cascades and will thus tend to isotropize
+lower energy cascade photons, thereby inducing a modulation in the anisotropy
+energy spectrum of the gamma-ray background. Here we present a simple,
+proof-of-concept calculation of the magnitude of this effect and demonstrate
+that current Fermi data already seem to prefer non-negligible IGMF values. The
+anisotropy energy spectrum of the Fermi gamma-ray background could thus be used
+as a probe of the IGMF strength.",1201.4405v3
+2012-01-30,"Fractional calculus, completely monotonic functions, a generalized Mittag-Leffler function and phase-space consistency of separable augmented densities","Under the separability assumption on the augmented density, a distribution
+function can be always constructed for a spherical population with the
+specified density and anisotropy profile. Then, a question arises, under what
+conditions the distribution constructed as such is non-negative everywhere in
+the entire accessible subvolume of the phase-space. We rediscover necessary
+conditions on the augmented density expressed with fractional calculus. The
+condition on the radius part R(r^2) -- whose logarithmic derivative is the
+anisotropy parameter -- is equivalent to R(1/w)/w being a completely monotonic
+function whereas the condition on the potential part is stated as its
+derivative up to the order not greater than 3/2-b being non-negative (where b
+is the central limiting value for the anisotropy parameter). We also derive the
+set of sufficient conditions on the separable augmented density for the
+non-negativity of the distribution, which generalizes the condition derived for
+the generalized Cuddeford system by Ciotti & Morganti to arbitrary separable
+systems. This is applied for the case when the anisotropy is parameterized by a
+monotonic function of the radius of Baes & Van Hese. The resulting criteria are
+found based on the complete monotonicity of generalized Mittag-Leffler
+functions.",1201.6113v1
+2012-03-02,Single Magnetic Atom on a Surface: Anisotropy Energy and Spin Density,"Studying single-atom magnetic anisotropy on surfaces enables the exploration
+of the smallest magnetic storage bit that can be built. In this work, magnetic
+anisotropy of a single rare-earth atom on a surface is studied computationally
+for the first time. The single adatom and its substrate surface are chosen to
+be a Dysprosium (Dy) atom and a copper-nitrite surface, respectively, where
+single transition-metal magnetic atoms on the same surface were previously
+studied one atom at a time by scanning tunneling microscopes. We propose
+unconventional f and d subshell symmetries so that following the
+first-principles calculations, simple pictorial analyses of the spin-density
+distribution can be performed for the first time, independently for both a
+rare-earth atom Dy and a transition-metal Fe. The magnetic anisotropy energy of
+Dy on the surface is calculated to be a factor of five larger than the previous
+highest one, reaching a record-high value of 31 meV.",1203.0420v1
+2012-03-02,Mismatch of conductivity anisotropy in the mixed and normal states of type-II superconductors,"We have calculated the Bardeen-Stephen contribution to the vortex viscosity
+for uniaxial anisotropic superconductors within the time-dependent
+Ginzburg-Landau (TDGL) theory. We focus our attention on superconductors with a
+mismatch of anisotropy of normal and superconducting characteristics. Exact
+asymptotics for the Bardeen-Stephen contribution have been derived in two
+limits: the cases of small and large electric field penetration depth (as
+compared to the coherence length). Also we suggest a variational procedure
+which allows us to calculate the vortex viscosity for superconductors with
+arbitrary ratio of the coherence lenght to the electric field penetration
+depth. The approximate analytical result is compared with numerical
+calculations. Finally, using a generalized TDGL theory, we prove that the
+viscosity anisotropy and, thus, the flux-flow conductivity anisotropy may
+depend on temperature.",1203.0459v2
+2012-03-09,Fractional quantum Hall states in two-dimensional electron systems with anisotropic interactions,"We study the anisotropic effect of the Coulomb interaction on a 1/3-filling
+fractional quantum Hall system by using an exact diagonalization method on
+small systems in torus geometry. For weak anisotropy the system remains to be
+an incompressible quantum liquid, although anisotropy manifests itself in
+density correlation functions and excitation spectra. When the strength of
+anisotropy increases, we find the system develops a Hall-smectic-like phase
+with a one-dimensional charge density wave order and is unstable towards the
+one-dimensional crystal in the strong anisotropy limit. In all three phases of
+the Laughlin liquid, Hall-smectic-like, and crystal phases the ground state of
+the anisotropic Coulomb system can be well described by a family of model wave
+functions generated by an anisotropic projection Hamiltonian. We discuss the
+relevance of the results to the geometrical description of fractional quantum
+Hall states proposed by Haldane [ Phys. Rev. Lett. 107 116801 (2011)].",1203.1982v2
+2012-03-09,Role of Fermi surface anisotropy in the study of gap anisotropy using magnetic-field-angle dependence of thermal oscillations in AyFe2-xSe2 superconductors,"We present a numerical study of the field-angle resolved oscillations of the
+thermal conductivity and specific heat under rotated magnetic field in the
+$A_y$Fe$_{2-x}$Se$_2$ [$A$=K,Rb,Cs,(Tl,K)] superconductors, using realistic
+two-band Fermi surface parameterization. Our key finding is that even for
+isotropic pairing on an anisotropic Fermi surface, the thermodynamic quantities
+exhibit substantial oscillatory behavior in the superconducting state, even
+much below the upper critical field. Furthermore, in multiband systems the
+competition of anisotropies between two Fermi surfaces can cause a double sign
+reversal of oscillations as a function of temperature, irrespective of gap
+anisotropy. Our findings put severe constraints on simple interpretations of
+field-angle resolved measurements widely used to identify the angular structure
+of the superconducting gap.",1203.2211v2
+2012-03-15,Azimuthal anisotropy in a jet absorption model with fluctuating initial geometry in heavy ion collisions,"The azimuthal anisotropy due to path-length dependent jet energy loss is
+studied in a simple jet absorption model that include event by event
+fluctuating Glauber geometry. Significant anisotropy coefficients v_n are
+observed for n=1,2 and 3, but they are very small for n>3. These coefficients
+are expected to result in a ""ridge"" for correlations between two independently
+produced jets. The correlations between the orientation of the n^{th}-order
+anisotropy induced by jet absorption (\Phi_n^{QP}) and the n^{th}-order
+participant plane (\Phi_n^{PP}) responsible for harmonic flow are studied.
+Tight correlations are observed for n=2 in mid-central collisions, but they
+weaken significantly for n\neq2. The correlations are positive for n>=3, but
+become negative in central collisions for n>3. The dispersion between
+\Phi_n^{QP} and \Phi_n^{PP} is expect to break the factorization of the Fourier
+coefficients from two-particle correlation v_{n,n} into the single particle
+v_n, and has important implications for the high-pT ridge phenomena.",1203.3265v2
+2012-04-09,Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV,"The azimuthal anisotropy of charged particles in PbPb collisions at
+nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS
+detector at the LHC over an extended transverse momentum (pt) range up to
+approximately 60 GeV. The data cover both the low-pt region associated with
+hydrodynamic flow phenomena and the high-pt region where the anisotropies may
+reflect the path-length dependence of parton energy loss in the created medium.
+The anisotropy parameter (v2) of the particles is extracted by correlating
+charged tracks with respect to the event-plane reconstructed by using the
+energy deposited in forward-angle calorimeters. For the six bins of collision
+centrality studied, spanning the range of 0-60% most-central events, the
+observed v2 values are found to first increase with pt, reaching a maximum
+around pt = 3 GeV, and then to gradually decrease to almost zero, with the
+decline persisting up to at least pt = 40 GeV over the full centrality range
+measured.",1204.1850v2
+2012-05-03,Cosmic Topology of Prism Double-Action Manifolds,"The cosmic microwave background (CMB) anisotropies in spherical 3-spaces with
+a non-trivial topology are studied. This paper discusses the special class of
+the so-called double-action manifolds, which are for the first time analysed
+with respect to their CMB anisotropies. The CMB anisotropies are computed for
+all prism double-action manifolds generated by a binary dihedral and a cyclic
+group with a group order of up to 180 leading to 33 different topologies.
+Several spaces are found which show a suppression of the CMB anisotropies on
+large angular distances as it is found on the real CMB sky. It turns out that
+two of these spaces possess Dirichlet domains which are not very far from
+highly symmetric polyhedra like Platonic or Archimedean ones.",1205.0660v2
+2012-05-10,"Multiboson spin-wave theory for Ba2CoGe2O7, a spin-3/2 easy-plane Neel antiferromagnet with strong single-ion anisotropy","We consider the square-lattice antiferromagnetic Heisenberg Hamiltonian
+extended with a single-ion axial anisotropy term as a minimal model for the
+multiferroic Ba2CoGe2O7. Developing a multiboson spin-wave theory, we
+investigate the dispersion of the spin excitations in this spin-3/2 system. As
+a consequence of a strong single-ion anisotropy, a stretching (longitudinal)
+spin-mode appears in the spectrum. The inelastic neutron scattering spectra of
+Zheludev et al. [Phys. Rev. B 68, 024428 (2003)] are successfully reproduced by
+the low energy modes in the multiboson spin-wave theory, and we anticipate the
+appearance of the spin stretching modes at 4meV that can be identified using
+the calculated dynamical spin structure factors. We expect the appearance of
+spin stretching modes for any S>1/2 compound where the single-ion anisotropy is
+significant.",1205.2196v2
+2012-05-21,Theoretical study of magnetic domain walls through a cobalt nanocontact,"To calculate the magnetic ground state of nanoparticles we present a
+self-consistent first principles method in terms of a fully relativistic
+embedded cluster multiple scattering Green's function technique. Based on the
+derivatives of the band energy, a Newton-Raphson algorithm is used to find the
+ground state configuration. The method is applied to a cobalt nanocontact that
+turned out to show a cycloidal domain wall configuration between oppositely
+magnetized leads. We found that a wall of cycloidal spin-structure is about 30
+meV lower in energy than the one of helical spin-structure. A detailed analysis
+revealed that the uniaxial on-site anisotropy of the central atom is mainly
+responsible to this energy difference. This high uniaxial anisotropy energy is
+accompanied by a huge enhancement and anisotropy of the orbital magnetic moment
+of the central atom. By varying the magnetic orientation at the central atom,
+we identified the term related to exchange couplings (Weiss-field term),
+various on-site anisotropy terms, and also those due to higher order
+spin-interactions.",1205.4579v1
+2012-06-25,Initial state anisotropies in ultrarelativistic heavy-ion collisions from the Monte Carlo Glauber model,"In hydrodynamicalmodeling of heavy-ion collisions the initial state spatial
+anisotropies translate into momentum anisotropies of the final state particle
+distributions. Thus, understanding the origin of the initial anisotropies and
+quantifying their uncertainties is important for the extraction of specific QCD
+matter properties, such as viscosity, from the experimental data. In this work
+we study the wounded nucleon approach in the Monte Carlo Glauber model
+framework, focusing especially on the uncertainties which arise from the
+modeling of the nucleon-nucleon interactions between the colliding nucleon
+pairs and nucleon-nucleon correlations inside the colliding nuclei. We compare
+the black disk model and a probabilistic profile function approach for the
+inelastic nucleon-nucleon interactions, and study the effects of initial state
+correlations using state-of-theart modeling of these.",1206.5720v1
+2012-06-29,Light-induced magnetization reversal of high-anisotropy TbCo alloy films,"Magnetization reversal using circularly polarized light provides a new way to
+control magnetization without any external magnetic field and has the potential
+to revolutionize magnetic data storage. However, in order to reach ultra-high
+density data storage, high anisotropy media providing thermal stability are
+needed. Here, we evidence all-optical magnetization switching for different
+TbxCo1-x ferrimagnetic alloy composition and demonstrate all-optical switching
+for films with anisotropy fields reaching 6 T corresponding to anisotropy
+constants of 3x106 ergs/cm3. Optical magnetization switching is observed only
+for alloys which compensation temperature can be reached through sample
+heating.",1206.6978v1
+2012-08-12,Measurement of the azimuthal anisotropy of neutral pions in PbPb collisions at sqrt(s(NN)) = 2.76 TeV,"First measurements of the azimuthal anisotropy of neutral pions produced in
+PbPb collisions at a center-of-mass energy of sqrt(s(NN)) = 2.76 TeV are
+presented. The amplitudes of the second Fourier component (v2) of the neutral
+pion azimuthal distributions are extracted using an event-plane technique. The
+values of v2 are studied as a function of the neutral pion transverse momentum
+(pt) for different classes of collision centrality in the kinematic range 1.6 <
+pt < 8.0 GeV, within the pseudorapidity interval abs(eta) < 0.8. The CMS
+measurements of v2(pt) are similar to previously reported neutral pion
+azimuthal anisotropy results from sqrt(s(NN)) = 200 GeV AuAu collisions at
+RHIC, despite a factor of about 14 increase in the center-of-mass energy. In
+the momentum range 2.5 < pt < 5.0 GeV, the neutral pion anisotropies are found
+to be smaller than those observed by CMS for inclusive charged particles.",1208.2470v2
+2012-08-27,Understanding TeV-band cosmic-ray anisotropy,"We investigate the temporal and spectral correlations between flux and
+anisotropy fluctuations of TeV-band cosmic rays in the light of recent data
+taken with IceCube. We find that for a conventional distribution of cosmic-ray
+sources the dipole anisotropy is higher than observed, even if source
+discreteness is taken into account. Moreover, even for a shallow distribution
+of galactic cosmic-ray sources and a reacceleration model, fluctuations arising
+from source discreteness provide a probability only of the order of 10% that
+the cosmic-ray anisotropy limits of the recent IceCube analysis are met. This
+probability estimate is nearly independent of the exact choice of source rate,
+but generous for a large halo size. The location of the intensity maximum far
+from the Galactic Center is naturally reproduced.",1208.5338v1
+2012-08-27,Anisotropy of photon production: Initial eccentricity or magnetic field,"Recent measurements of the azimuthal anisotropy of direct photons in
+heavy-ion collisions at the energies of RHIC show that it is of the same order
+as the hadronic one. This finding appears to contradict the expected dominance
+of photon production from a quark-gluon plasma at an early stage of a heavy-ion
+collision. A possible explanation of the strong azimuthal anisotropy of the
+photons, given recently, is based on the presence of a large magnetic field in
+the early phase of a collision. In this letter, we propose a method to
+experimentally measure the degree to which a magnetic field in heavy-ion
+collisions is responsible for the observed anisotropy of photon production. The
+experimental test proposed in this letter may potentially change our
+understanding of the non-equilibrium stage and possible thermalization in
+heavy-ion collisions.",1208.5502v3
+2012-09-01,Anisotropy and universality: Critical Binder cumulant of the two-dimensional Ising model,"We reanalyze transfer matrix and Monte Carlo results for the critical Binder
+cumulant U* of an anisotropic two-dimensional Ising model on a square lattice
+in a square geometry with periodic boundary conditions. Spins are coupled
+between nearest neighboring sites and between next-nearest neighboring sites
+along one of the lattice diagonals. We find that U* depends only on the
+asymptotic critical long-distance features of the anisotropy, irrespective of
+its realization through ferromagnetic or antiferromagnetic next-nearest
+neighbor couplings. We modify an earlier renormalization-group calculation to
+obtain a quantitative description of the anisotropy dependence of U*. Our
+results support our recent claim towards the validity of universality for
+critical phenomena in the presence of a weak anisotropy.",1209.0105v2
+2012-10-05,Anisotropy of spin relaxation in metals,"The concept of anisotropy of spin relaxation in non-magnetic metals with
+respect to the spin direction of the injected electrons relative to the crystal
+orientation is introduced. The effect is related to an anisotropy of the
+Elliott-Yafet parameter, arising from a modulation of the decomposition of the
+spin-orbit Hamiltonian into spin-conserving and spin-flip terms as the spin
+quantization axis is varied. This anisotropy, reaching gigantic values for
+uniaxial transition-metals (e.g. 830% for hcp Hf) as density-functional
+calculations show, is related to extended ""spin-flip hot areas"" on the Fermi
+surface created by the proximity of extended sheets of the surface, or
+""spin-flip hot loops"" at the Brillouin zone boundary, and has no theoretical
+upper limit. Possible ways of measuring the effect as well as consequences in
+application are briefly outlined.",1210.1801v1
+2012-10-10,Distance-Redshift Relations in an Anisotropic Cosmological Model,"In this paper we study an anisotropic model generated from a particular
+Bianchi type-III metric, which is a generalization of G\""odel's metric and an
+exact solution of Einstein's field equations. We analyse type Ia supernova
+data, namely the SDSS sample calibrated with the MLCS2k2 fitter, and we verify
+in which ranges of distances and redshifts the anisotropy could be observed. We
+also consider, in a joint analysis, the position of the first peak in the CMB
+anisotropy spectrum, as well as current observational constraints on the Hubble
+constant. We conclude that a small anisotropy is permitted by the data, and
+that more accurate measurements of supernova distances above z = 2 might
+indicate the existence of such anisotropy in the universe.",1210.2909v2
+2012-10-24,Alternating domains with uniaxial and biaxial magnetic anisotropy in epitaxial Fe films on BaTiO3,"We report on domain formation and magnetization reversal in epitaxial Fe
+films on ferroelectric BaTiO3 substrates with ferroelastic a-c stripe domains.
+The Fe films exhibit biaxial magnetic anisotropy on top of c domains with
+out-of-plane polarization, whereas the in-plane lattice elongation of a domains
+induces uniaxial magnetoelastic anisotropy via inverse magnetostriction. The
+strong modulation of magnetic anisotropy symmetry results in full imprinting of
+the a-c domain pattern in the Fe films. Exchange and magnetostatic interactions
+between neighboring magnetic stripes further influence magnetization reversal
+and pattern formation within the a and c domains.",1210.6533v2
+2012-11-02,Symmetry Conditions for Non-reciprocal Light Propagation in Magnetic Crystals,"Recent studies demonstrated the violation of reciprocity in optical processes
+in low-symmetry magnetic crystals. In these crystals the speed of light can be
+different for counter-propagating beams. Correspondingly, they can show strong
+directional anisotropies such as direction dependent absorption also called
+directional dichroism[S. Bord\'acs et al., Nat. Phys. 8, 734 (2012); M. Saito
+et al., J. Phys. Soc. Jpn. 77, 013705 (2008)]. Based on symmetry
+considerations, we identify the magnetic point groups of materials which can
+host such directional anisotropies and also provide a list of possible
+candidate materials to observe these phenomena. In most of these cases, the
+symmetry of the crystal allows directional anisotropy not only for optical
+processes but also for the propagation of beams of particles and scalar waves.
+We also predict new types of directional optical anisotropies -- besides the
+optical magnetoelectric effect and the magnetochiral dichroism investigated so
+far -- and specify the magnetic point groups of crystals where they can emerge.",1211.0530v2
+2012-11-27,Monte Carlo simulation of the effects of higher order anisotropy on the spin reorientation transition in the two dimensional Heisenberg model with long range interactions,"The strength of perpendicular anisotropy is known to drive the spin
+reorientation in thin magnetic films. Here we consider the effect different
+order anisotropies have on two phase transitions; the spin reorientation
+transition and the orientational order transition. We find that the relative
+magnitude of different order anisotropies can significantly enhance or suppress
+the degree to which the system reorients. Specifically Monte Carlo simulations
+reveal significant changes in the cone angle and planar magnetization. In order
+to facilitate rapid computation we have developed a stream processing
+technique, suitable for use on GPU systems, for computing the transition
+probabilities in two dimensional systems with dipole interactions.",1211.6234v1
+2012-12-13,Constraints on the origin of cosmic rays above $10^{18}$ eV from large scale anisotropy searches in data of the Pierre Auger Observatory,"A thorough search for large scale anisotropies in the distribution of arrival
+directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger
+Observatory is reported. For the first time, these large scale anisotropy
+searches are performed as a function of both the right ascension and the
+declination and expressed in terms of dipole and quadrupole moments. Within the
+systematic uncertainties, no significant deviation from isotropy is revealed.
+Upper limits on dipole and quadrupole amplitudes are derived under the
+hypothesis that any cosmic ray anisotropy is dominated by such moments in this
+energy range. These upper limits provide constraints on the production of
+cosmic rays above $10^{18}$ eV, since they allow us to challenge an origin from
+stationary galactic sources densely distributed in the galactic disk and
+emitting predominantly light particles in all directions.",1212.3083v1
+2012-12-24,Excited states of the quasi-one-dimensional hexagonal quantum antiferromagnets,"We investigate the excited states of the quasi-one-dimensional quantum
+antiferromagnets on hexagonal lattices, including the longitudinal modes based
+on the magnon-density waves. A model Hamiltonian with a uniaxial single-ion
+anisotropy is first studied by a spin-wave theory based on the one-boson
+method; the ground state thus obtained is employed for the study of the
+longitudinal modes. The full energy spectra of both the transverse modes (i.e.,
+magnons) and the longitudinal modes are obtained as functions of the
+nearest-neighbor coupling and the anisotropy constants. We have found two
+longitudinal modes due to the non-collinear nature of the triangular
+antiferromagnetic order, similar to that of the phenomenological field theory
+approach by Affleck. The excitation energy gaps due to the anisotropy and the
+energy gaps of the longitudinal modes without anisotropy are then investigated.
+We then compare our results for the longitudinal energy gaps at the magnetic
+wavevectors with the experimental results for several antiferromagnetic
+compounds with both integer and non-integer spin quantum numbers, and we find
+good agreement after the higher-order contributions are included in our
+calculations.",1212.5924v3
+2012-12-28,Study of the magnetic anisotropy in a planar model of the La2CuO4,"We study the anisotropy energy in a planar model for the Cu-O layers of the
+La2CuO4 investigated in previous works. The Tight-Binding (TB) potential of the
+model was extended out of the validity region with the purpose of incorporate
+it in the potential. Next, the spin-orbit operator was considered in the
+Hartree Fock solution of the full HF problem. It follows that in spite of the
+fact that the extended potential possesses the square symmetry of the
+crystalline structure, the anisotropy energy vanishes in its purely 2D
+formulation. The result indicates that for the prediction by the model of the
+observed non vanishing magnetic anisotropy at zero doping and temperature in
+La2CuO4, its formulation requires of a 3D representation of its Wannier
+orbitals and the use of d like orbitals. The consideration of more realistic 3D
+character of the model, by including multiple CuO planes, also could be
+important due to the argued absence of long range order in 2D.",1212.6460v1
+2013-01-23,The investigations of anisotropy in orientations of galaxies,"In 1994 Parnovsky, Karachentsev and Karachentseva suggested a modified method
+for investigation of the orientations of galaxies. Using this method they
+analyzed galaxies from the UGC and ESO catalogues, as well as from their's own
+catalogue inclusive of flat, edge-on galaxies. They found statistically
+significant anisotropy in the galaxies orientations'. In 1995 Flin suggested
+that this anisotropy has to be specific to LOcal Supercluster (LSC) In the
+present paper, using the method proposed by Parnovsky, Karachentsev and
+Karachentseva in 1994, we analyzed orientation of galaxies in the sample of
+galaxies belonging to LSC founding only a weak anisotropy. The relation of this
+method to Hawley and Peebles (1975) method of the investigation of the
+orientation of galaxies was discussed as well.",1301.5477v1
+2013-02-22,Constraints on spacetime anisotropy and Lorentz violation from the GRAAL experiment,"The GRAAL experiment could constrain the variations of the speed of light.
+The anisotropy of the speed of light may imply that the spacetime is
+anisotropic. Finsler geometry is a reasonable candidate to deal with the
+spacetime anisotropy. In this paper, the Lorentz invariance violation (LIV) of
+the photon sector is investigated in the locally Minkowski spacetime. The
+locally Minkowski spacetime is a class of flat Finsler spacetime and refers a
+metric with the anisotropic departure from the Minkowski one. The LIV matrices
+used to fit the experimental data are represented in terms of these metric
+deviations. The GRAAL experiment constrains the spacetime anisotropy to be less
+than \(10^{-14}\). In addition, we find that the simplest Finslerian photon
+sector could be viewed as a geometric representation of the photon sector in
+the minimal standard model extension (SME).",1302.5486v2
+2013-03-14,Thermal Stability and Electrical Control of Magnetization of Heusler/Oxide Interface and Non-collinear Spin Transport of Its Junction,"Towards next-generation spintronics devices, such as computer memories and
+logic chips, it is necessary to satisfy high thermal stability, low-power
+consumption and high spin-polarization simultaneously. Here, from
+first-principles, we investigate thermal stability (both structure and
+magnetization) and the electric field control of magnetic anisotropy on Co2FeAl
+(CFA)/MgO. A phase diagram of structural thermal stability of the CFA/MgO
+interface is illustrated. An interfacial perpendicular-anisotropy, coming from
+the Fe-O orbital hybridization, provides high magnetic thermal stability and a
+low stray field. We find an electric-field-induced giant modification of such
+perpendicular-anisotropy via a great magnetoelectric effect (the anisotropy
+energy coefficient beta~10-7 erg/V cm). Our spin electronic-structure and
+non-collinear transport calculations indicate high spin-polarized interfacial
+states and good magnetoresistance properties of CFA/MgO/CFA perpendicular
+magnetic tunnel junctions.",1303.3473v2
+2013-03-25,Field-angle-resolved anisotropy in superconducting CeCoIn5 using realistic Fermi surfaces,"We compute the field-angle-resolved specific heat and thermal conductivity
+using realistic model band structure for the heavy-fermion superconductor
+CeCoIn5 to identify the gap structure and location of nodes. We use a two-band
+tight-binding parametrization of the band dispersion as input for the
+self-consistent calculations in the quasiclassical formulation of the
+superconductivity. Systematic analysis shows that modest in-plane anisotropy in
+the density of states and Fermi velocity in tetragonal crystals significantly
+affects the fourfold oscillations in thermal quantities, when the magnetic
+field is rotated in the basal plane. The Fermi surface anisotropy substantially
+shifts the location of the lines in the H-T plane, where the oscillations
+change sign compared to quasicylindrical model calculations. In particular, at
+high fields, the anisotropy and sign reversal are found even for isotropic
+gaps. Our findings imply that a simultaneous analysis of the specific heat and
+thermal conductivity, with an emphasis on the low energy sector, is needed to
+restrict potential pairing scenarios in multiband superconductors. We discuss
+the impact of our results on recent measurements of the Ce-115 family, namely
+CeTIn5 with T=Co,Rh,Ir.",1303.6258v1
+2013-03-29,Anisotropic Non-Gaussianity from a Two-Form Field,"We study an inflationary scenario with a two-form field to which an inflaton
+couples non-trivially. First, we show that anisotropic inflation can be
+realized as an attractor solution and that the two-form hair remains during
+inflation. A statistical anisotropy can be developed because of a cumulative
+anisotropic interaction induced by the background two-form field. The power
+spectrum of curvature perturbations has a prolate-type anisotropy, in contrast
+to the vector models having an oblate-type anisotropy. We also evaluate the
+bispectrum and trispectrum of curvature perturbations by employing the in-in
+formalism based on the interacting Hamiltonians. We find that the non-linear
+estimators $f_{NL}$ and $\tau_{NL}$ are correlated with the amplitude $g_*$ of
+the statistical anisotropy in the power spectrum. Unlike the vector models,
+both $f_{NL}$ and $\tau_{NL}$ vanish in the squeezed limit. However, the
+estimator $f_{NL}$ can reach the order of 10 in the equilateral and enfolded
+limits. These results are consistent with the latest bounds on $f_{NL}$
+constrained by Planck.",1303.7340v2
+2013-04-11,Theory of magnetic small-angle neutron scattering of two-phase ferromagnets,"Based on micromagnetic theory we have derived analytical expressions for the
+magnetic small-angle neutron scattering (SANS) cross section of a two-phase
+particle-matrix-type ferromagnet. The approach---valid close to magnetic
+saturation---provides access to several features of the spin structure such as
+perturbing magnetic anisotropy and magnetostatic fields. Depending on the
+applied magnetic field and on the magnitude $H_p$ of the magnetic anisotropy
+field relative to the magnitude $\Delta M$ of the jump in the longitudinal
+magnetization at the particle-matrix interface, we observe a variety of angular
+anisotropies in the magnetic SANS cross section. In particular, the model
+explains the ""clover-leaf""-shaped angular anisotropy which was previously
+observed for several nanostructured magnetic materials, and it provides access
+to the magnetic interaction parameters such as the average exchange-stiffness
+constant. It is also shown that the ratio $H_p / \Delta M$ decisively
+determines the asymptotic power-law exponent and the range of spin-misalignment
+correlations.",1304.3214v1
+2013-04-10,Environment-induced anisotropy and the sensitivity of the radical pair mechanism in the avian compass,"Several experiments over the years have shown that the Earth's magnetic field
+is essential for orientation in birds migration. The most promising explanation
+for this orientation is the photo-stimulated radical pair (RP) mechanism. In
+order to define a reference frame for the orientation task radicals must have
+an intrinsic anisotropy. We show that this kind of anisotropy, and consequently
+the entanglement in the model, are not necessary for the proper functioning of
+the compass. Classically correlated initial conditions for the RP, subjected to
+a fast decoherence process, are able to provide the anisotropy required. Even a
+dephasing environment can provide the necessary frame for the compass to work,
+and also implies fast decay of any quantum correlation in the system without
+damaging the orientation ability. This fact significantly expands the range of
+applicability of the RP mechanism providing more elements for experimental
+search.",1304.3452v2
+2013-04-19,Energetic Particle Diffusion In Critically Balanced Turbulence,"Observations and modelling suggest that the fluctuations in magnetised
+plasmas exhibit scale-dependent anisotropy, with more energy in the
+fluctuations perpendicular to the mean magnetic field than in the parallel
+fluctuations and the anisotropy increasing at smaller scales. The
+scale-dependence of the anisotropy has not been studied in full-orbit
+simulations of particle transport in turbulent plasmas so far. In this paper,
+we construct a model of critically balanced turbulence, as suggested by
+\cite{GoSr1995}, and calculate energetic particle spatial diffusion
+coefficients using full-orbit simulations. The model uses an enveloped
+turbulence approach, where each 2-dimensional wave mode with wavenumber
+$k_\perp$ is packed into envelopes of length $L$ following the critical balance
+condition, $L\propto k_\perp^{-2/3}$, with the wave mode parameters changing
+between envelopes. Using full-orbit particle simulations, we find that both the
+parallel and perpendicular diffusion coefficients increase by a factor 2,
+compared to previous models with scale-independent anisotropy.",1304.5399v1
+2013-05-08,Magnetic Exchange Coupling and Anisotropy of 3d Transition-Metal Nanowire on the Surface of Graphyne Sheet,"Using density functional theory plus Hubbard-U (DFT+U) approach, we find that
+quasi one-dementation(1D) 3d transition metal(TM) zigzag nanowire can be
+constructed by TM adsorbed on the surface of graphyne sheet. The results show
+that the TM exchange coupling of the zigzag nanowire mediated by sp hybridized
+carbon atoms gives rise to long range ferromagnetic order except for Cr with
+anti-ferromagnetic order. The magnetic exchange interaction of TM chains
+follows like-Zener's p_z-d exchange mechanism: the coexistence of out-of plane
+p_z-d and in-plane p_x-y-d exchange. Finally, by including spin-orbit
+interactions within spin-DFT, we calculate the magnetic anisotropy energy of
+the TM chain on graphyne. We find that the Fe and Co chains show considerable
+magnetic anisotropy energy (MAE) and orbital magnetic moment. The easy axis of
+V, Cr, Mn and Fe chains is perpendicular to the surface, whereas the easy axis
+of Co lies in the surface. Moreover, only V chain shows relatively larger
+in-plane anisotropy. Our results open a new route to realize the applications
+of graphyne in spintronics.",1305.1791v2
+2013-05-09,Review of Anisotropic Terahertz Material Response,"Anisotropy is ubiquitous in solids and enhanced in low-dimensional materials.
+In response to an electromagnetic wave, anisotropic absorptive and refractive
+properties result in dichroic and birefringent optical phenomena both in the
+linear and nonlinear optics regimes. Such material properties have led to a
+diverse array of useful polarization components in the visible and
+near-infrared, but mature technology is non-existent in the terahertz (THz).
+Here, we review several novel types of anisotropic material responses observed
+in the THz frequency range, including both linear and circular anisotropy,
+which have long-term implications for the development of THz polarization
+optics. We start with the extreme linear anisotropy of macroscopically aligned
+carbon nanotubes, arising from their intrinsically anisotropic dynamic
+conductivity. Magnetically induced anisotropy will then be reviewed, including
+the giant Faraday effects observed in semiconductors, semimetals, and
+two-dimensional electron systems.",1305.1987v1
+2013-05-10,Effects of spacetime anisotropy on the galaxy rotation curves,"The observations on galaxy rotation curves show significant discrepancies
+from the Newtonian theory. This issue could be explained by the effect of the
+anisotropy of the spacetime. Conversely, the spacetime anisotropy could also be
+constrained by the galaxy rotation curves. Finsler geometry is a kind of
+intrinsically anisotropic geometry. In this paper, we study the effect of the
+spacetime anisotropy at the galactic scales in the Finsler spacetime. It is
+found that the Finslerian model has close relations with the Milgrom's MOND. By
+performing the best-fit procedure to the galaxy rotation curves, we find that
+the anisotropic effects of the spacetime become significant when the Newtonian
+acceleration \(GM/r^2\) is smaller than the critical acceleration \(a_0\).
+Interestingly, the critical acceleration \(a_0\), although varies between
+different galaxies, is in the order of magnitude \(cH_0/2\pi\sim 10^{-10}
+\rm{m\,\, s^{-2}}\).",1305.2314v2
+2013-06-05,Constraints on Spatial Variations in the Fine-Structure constant from Planck,"We use the Cosmic Microwave Background (CMB) anisotropy data from Planck to
+constrain the spatial fluctuations of the fine-structure constant \alpha.
+Through Thompson scattering of CMB photons, spatial anisotropies of \alpha lead
+to higher-order correlations in the CMB anisotropies. We use a quadratic
+estimator based on the four-point correlation function of the CMB temperature
+anisotropy to extract the angular power spectrum of the spatial variation of
+the fine-structure constant projected along the line of sight at the last
+scattering surface. At tens of degree angular scales and above, we constrain
+the rms fluctuations of the fine structure constant to be \delta
+\alpha/\alpha_0= (1.34 +/- 5.82) x 10^-2 at the 95% confidence level with
+respect to the standard value \alpha_0. We find no evidence for a spatially
+varying \alpha at a redshift of 10^3.",1306.1232v1
+2013-06-20,Review of the anisotropy working group at UHECR-2012,"The study of ultra-high energy cosmic rays (UHECRs) has recently experienced
+a jump in statistics as well as improved instrumentation. This has allowed a
+better sensitivity in searching for anisotropies in the arrival directions of
+cosmic rays. In this written version of the presentation given by the
+inter-collaborative ""Anisotropy Working Group"" at the International Symposium
+on Future Directions in UHECR physics at CERN in February 2012, we report on
+the current status for anisotropy searches in the arrival directions of UHECRs.",1306.4998v1
+2013-06-28,Velocity Anisotropy and Shape Bias in the Caustic Technique,"We use the Millennium Simulation to quantify the statistical accuracy and
+precision of the escape velocity technique for measuring cluster-sized halo
+masses at z~0.1. We show that in 3D, one can measure nearly unbiased (<4%) halo
+masses (>1.5x10^14 M_solar h^-1) with 10-15% scatter. Line-of-sight projection
+effects increase the scatter to ~25%, where we include the known velocity
+anisotropies. The classical ""caustic"" technique incorporates a calibration
+factor which is determined from N-body simulations. We derive and test a new
+implementation which eliminates the need for calibration and utilizes only the
+observables: the galaxy velocities with respect to the cluster mean v, the
+projected positions r_p, an estimate of the Navarro-Frenk-White (NFW) density
+concentration and an estimate of the velocity anisotropies, beta. We find that
+differences between the potential and density NFW concentrations induce a 10%
+bias in the caustic masses. We also find that large (100%) systematic errors in
+the observed ensemble average velocity anisotropies and concentrations
+translate to small (5%-10%) biases in the inferred masses.",1307.0018v1
+2013-07-09,Effects of anisotropy in a nonlinear crystal for squeezed vacuum generation,"Squeezed vacuum (SV) can be obtained by an optical parametric amplifier (OPA)
+with the quantum vacuum state at the input. We are interested in a degenerate
+type-I OPA based on parametric down-conversion (PDC) where due to phase
+matching requirements, an extraordinary polarized pump must impinge onto a
+birefringent crystal with a large \chi(2) nonlinearity. As a consequence of the
+optical anisotropy of the medium, the direction of propagation of the pump
+wavevector does not coincide with the direction of propagation of its energy,
+an effect known as transverse walk-off. For certain pump sizes and crystal
+lengths, the transverse walk-off has a strong influence on the spatial spectrum
+of the generated radiation, which in turn affects the outcome of any experiment
+in which this radiation is employed. In this work we propose a method that
+reduces the distortions of the two-photon amplitude (TPA) of the states
+considered, by using at least two consecutive crystals instead of one. We show
+that after anisotropy compensation the TPA becomes symmetric, allowing for a
+simple Schmidt expansion, a procedure that in practice requires states that
+come from experimental systems free of anisotropy effects.",1307.2405v1
+2013-07-09,Temperature dependence of the switching field distributions in all-perpendicular spin-valve nanopillars,"We present temperature dependent switching measurements of the Co/Ni
+multilayered free element of 75 nm diameter spin-valve nanopillars. Angular
+dependent hysteresis measurements as well as switching field measurements taken
+at low temperature are in agreement with a model of thermal activation over a
+perpendicular anisotropy barrier. However, the statistics of switching (mean
+switching field and switching variance) from 20 K up to 400 K are in
+disagreement with a N\'{e}el-Brown model that assumes a temperature independent
+barrier height and anisotropy field. We introduce a modified N\'{e}el-Brown
+model thats fit the experimental data in which we take a $T^{3/2}$ dependence
+to the barrier height and the anisotropy field due to the temperature dependent
+magnetization and anisotropy energy.",1307.2496v1
+2013-07-10,Cherenkov sound on a surface of a topological insulator,"Topological insulators are currently of considerable interest due to peculiar
+electronic properties originating from helical states on their surfaces. Here
+we demonstrate that the sound excited by helical particles on surfaces of
+topological insulators has several exotic properties fundamentally different
+from sound propagating in non-helical or even isotropic helical systems.
+Specifically, the sound may have strictly forward propagation absent for
+isotropic helical states. Its dependence on the anisotropy of the realistic
+surface-states is of distinguished behavior which may be used as an alternative
+experimental tool to measure the anisotropy strength. Fascinating from the
+fundamental point of view backward, or anomalous, Cherenkov sound is excited
+above the critical angle $\pi/2$ when the anisotropy exceeds a critical value.
+Strikingly, at strong anisotropy the sound localizes into a few forward and
+backward beams propagating along specific directions.",1307.2777v2
+2013-08-04,Anisotropy studies with the Pierre Auger Observatory,"We report recent results from the Pierre Auger Observatory about the study of
+the anisotropy in the arrival directions of ultra-high energy cosmic rays. We
+present the results of the search for a dipolar anisotropy at the EeV energy
+scale. Measurements of the phase and the amplitude of the first harmonic
+modulation in the right-ascension distribution are discussed. For cosmic rays
+with energies above 55 EeV, we present an update of the search for correlations
+between their arrival directions and the positions of active galactic nuclei
+from the Veron-Cetty and Veron catalog. We also discuss the results of
+correlation analyses applied to other populations of extragalactic objects.
+Finally we present the search for anisotropies in the data without the usage of
+astronomical catalogues.",1308.0820v1
+2013-08-15,Magnetic fields from inflation: The CMB temperature anisotropies,"The cosmic microwave background (CMB) temperature anisotropies from
+primordial magnetic fields are studied. In addition to the known passive and
+the compensated mode we discuss an inflationary magnetic mode in the curvature
+perturbation, present when magnetic fields are generated during inflation. This
+mode is absent if the generation mechanism is causal, e.g. a phase transition.
+We compute and discuss the effect of this mode on the observed CMB anisotropy
+spectrum, in comparison with the passive and compensated ones. We find that it
+dominates the CMB anisotropy, and consequently leads to stronger constraints on
+the amplitude $B_{1\,{\rm Mpc}}$ and spectral index $n_B$ of the magnetic field
+than what usually found in CMB analyses from the compensated mode. This happens
+in particular for spectral indexes $n_B>-3$: the inflationary magnetic mode is
+always scale invariant, therefore through this mode even a magnetic field with
+a spectrum which is not scale invariant can leave a detectable signal in the
+CMB at large scales.",1308.3348v2
+2013-08-18,Spin excitation anisotropy as a probe of orbital ordering in the paramagnetic tetragonal phase of superconducting BaFe1.904Ni0.096As2,"We use polarized neutron scattering to demonstrate that in-plane spin
+excitations in electron doped superconducting BaFe1.904Ni0.096As2 (Tc=19.8 K)
+change from isotropic to anisotropic in the tetragonal phase well above the
+antiferromagnetic (AF) ordering and tetragonal-to-orthorhombic lattice
+distortion temperatures (Tn=Ts=33 K) without an uniaxial pressure. While the
+anisotropic spin excitations are not sensitive to the AF order and
+tetragonal-to-orthorhombic lattice distortion, superconductivity induces
+further anisotropy for spin excitations along the [1,1,0] and [1,-1,0]
+directions. These results indicate that the spin excitation anisotropy is a
+probe of the electronic anisotropy or orbital ordering in the tetragonal phase
+of iron pnictides.",1308.3858v1
+2013-09-16,Optical Anisotropy in Bismuth Titanate: An Experimental and Theoretical Study,"We report experimental and theoretical investigation of anisotropy in optical
+properties and their origin in the ferroelectric and paraelectric phases of
+bismuth titanate. Room temperature ellipsometric measurements performed on
+pulsed laser deposited bismuth titanate thin films of different orientations
+show anisotropy in the dielectric and optical constants, Subsequent
+first-principles calculations performed on the ground state structures of
+ferroelectric and high temperature paraelectric phases of bismuth titanate show
+that the material demonstrates anisotropic optical behavior in both
+ferroelectric and paraelectric phases. We further show that O 2p to Ti 3d
+transition is the primary origin of optical activity of the material while
+optical anisotropy results from the asymmetrically oriented Ti-O bonds in TiO6
+octehdra in the unit cell.",1309.4056v1
+2013-10-04,In-plane spin excitation anisotropy in the paramagnetic phase of NaFeAs,"We use unpolarized and polarized inelastic neutron scattering to study
+low-energy spin excitations in NaFeAs, which exhibits a
+tetragonal-to-orthorhombic lattice distortion at $T_s\approx 58$ K followed by
+a collinear antiferromagnetic (AF) order below $T_N\approx 45$ K. In the AF
+ordered state ($T<T_N$), spin waves are entirely c-axis polarized below
+$\sim$10 meV, exhibiting a gap of $\sim4$ meV at the AF zone center and
+disperse to $\sim$7 meV near the c-axis AF zone boundary. On warming to the
+paramagnetic state with orthorhombic lattice distortion ($T_N<T<T_s$), spin
+excitations become anisotropic within the FeAs plane. Upon further warming to
+the paramagnetic tetragonal state ($T>T_s$), spin excitations become more
+isotropic. Since similar magnetic anisotropy is also observed in the
+paramagnetic tetragonal phase of superconducting
+BaFe$_{1.904}$Ni$_{0.096}$As$_2$, our results suggest that the spin excitation
+anisotropy in superconducting iron pnictides originates from similar anisotropy
+already present in their parent compounds.",1310.1143v1
+2013-10-23,Anisotropy parameters in two-colour two-photon above threshold ionization,"We employ the time-dependent R-Matrix (TDRM) method to calculate anisotropy
+parameters for positive and negative sidebands of selected harmonics generated
+by two-color two-photon above threshold ionization of argon. We consider odd
+harmonics of an 800 nm field ranging from the 13th to 19th harmonic, overlapped
+by a fundamental 800 nm IR field. The anisotropy parameters obtained using the
+TDRM method are compared with those obtained using a second order perturbation
+theory with a model potential (MP) approach and a soft photon approximation
+(SPA) approach. Where available, a comparison is also made to published
+experimental results. All three theoretical approaches provide similar values
+for anisotropy parameters. The TDRM approach obtains values that are closest to
+published experimental values. At high photon energies, the differences between
+each of the theoretical methods become less significant.",1310.6190v1
+2013-11-05,Effect of disorder on the resistivity anisotropy near the electronic nematic phase transition in pure and electron-doped BaFe$_2$As$_2$,"We show that the strain-induced resistivity anisotropy in the tetragonal
+state of the representative underdoped Fe-arsenides BaFe$_2$As$_2$,
+Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ and Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$ is
+independent of disorder over a wide range of defect and impurity
+concentrations. This result demonstrates that the anisotropy in the in-plane
+resistivity in the paramagnetic orthorhombic state of this material is not due
+to elastic scattering from anisotropic defects, and is most easily understood
+in terms of an intrinsic anisotropy in the electronic structure.",1311.0933v2
+2013-11-22,Full-Heusler Co2FeSi alloy thin films with perpendicular magnetic anisotropy induced by MgO-interface,"The authors demonstrated that L21-ordered full-Heusler Co2FeSi (CFS) alloy
+film with thickness of 100 nm were formed by facing targets sputtering (FTS)
+method at a substrate temperature TS = 300 deg C. Degrees of L21- and B2- order
+for the film were 0.37, and 0.96, respectively. Furthermore, full-Heusler CFS
+alloy thin films with perpendicular magnetic anisotropy (PMA) induced by
+MgO-interface magnetic anisotropy were successfully formed by the FTS method.
+The CFS/MgO stacking layers showed PMA when dCFS was 0.6 nm <= dCFS <= 1.0 nm.
+The PMA in these structures resulted from the CFS/MgO interfacial perpendicular
+magnetic anisotropy.",1311.5670v2
+2013-12-03,Depth dependent magnetization profiles of hybrid exchange springs,"We report on the magnetization depth profile of a hybrid exchange spring
+system in which a Co/Pd multilayer with perpendicular anisotropy is coupled to
+a CoFeB thin film with in-plane anisotropy. The competition between these two
+orthogonal anisotropies promotes a strong depth dependence of the magnetization
+orientation. The angle of the magnetization vector is sensitive both to the
+strength of the individual anisotropies and to the local exchange constant, and
+is thus tunable by changing the thickness of the CoFeB layer and by
+substituting Ni for Pd in one layer of the Co/Pd stack. The resulting magnetic
+depth profiles are directly probed by element specific x-ray magnetic circular
+dichroism (XMCD) of the Co, Fe, and Ni layers located at different average
+depths. The experimental results are corroborated by micromagnetic simulations.",1312.0878v1
+2013-12-04,Rashba Spin-Orbit Anisotropy and the Electric Field Control of Magnetism,"The control of the magnetism of ultra-thin ferromagnetic layers using an
+electric field rather than a current, if large enough, would lead to many
+technologically important applications. To date, while it is usually assumed
+the changes in the magnetic anisotropy, leading to such a control, arises from
+surface charge doping of the magnetic layer, a number of key experiments cannot
+be understood within such a scenario. Much studied is the fact that, for
+non-magnetic metals or semi-conductors, a large surface electric field gives
+rise to a Rashba spin-orbit coupling which leads to a spin-splitting of the
+conduction electrons. For a magnet, this splitting is modified by the exchange
+field resulting in a large magnetic anisotropy energy via the
+Dzyaloshinskii-Moriya mechanism. This different, yet traditional, path to an
+electrically induced anisotropy energy can explain the electric field,
+thickness, and material dependence reported in many experiments.",1312.1021v1
+2013-12-04,Anisotropies of ultra-high energy cosmic rays diffusing from extragalactic sources,"We obtain the dipolar anisotropies in the arrival directions of ultra-high
+energy cosmic rays diffusing from nearby extragalactic sources. We discuss both
+the energy regime of spatial diffusion and the quasi-rectilinear one leading to
+just angular diffusion at higher energies. We obtain analytic results for the
+anisotropies from a single source which are validated using two different
+numerical simulations. For a scenario with a few sources in the local
+supercluster (with the closest source at a typical distance of few to tens of
+Mpc), we discuss the possible transition between the case in which the
+anisotropies are dominated by a few sources at energies below few EeV towards
+the regime in which many sources contribute at higher energies. The effect of a
+non-isotropic source distribution is also discussed, showing that it can
+significantly affect the observed dipole.",1312.1366v1
+2013-12-05,Hysteresis behavior of the anisotropic quantum Heisenberg model driven by periodic magnetic field,"Dynamic behavior of a quantum Heisenberg ferromagnet in the presence of a
+periodically oscillating magnetic field has been analyzed by means of the
+effective field theory with two spin cluster. The dynamic equation of motion
+has been constructed with the help of a Glauber type stochastic process and
+solved for a simple cubic lattice. After the phase diagrams given, the behavior
+of the hysteresis loop area, coercive field and remanent magnetization with the
+anisotropy in the exchange interaction has been investigated in detail.
+Especially, by comparing of the magnitudes of the hysteresis loop area in the
+high anisotropy limit (i.e. Ising model) and low anisotropy limit (i.e.
+isotropic Heisenberg model), detailed description of the hysteresis loop area
+with the anisotropy in the exchange interaction given. Some interesting
+features have been obtained about this behavior as well as in phase diagrams
+such as tricritical points.",1312.1647v1
+2013-12-13,Combined Flux and Anisotropy Searches Improve Sensitivity to Gamma Rays from Dark Matter,"Searches for dark matter annihilation signals in the diffuse gamma-ray
+background are promising. We present the first comprehensive study utilizing
+both flux and anisotropy, using the example of a spectral line signal. Besides
+improving sensitivity, a combined analysis will help separately determine the
+particle properties of dark matter and the cosmological aspects of its clumping
+into halo substructure. The significance of a signal in a shot-noise-dominated
+anisotropy analysis increases linearly with time $t$, as opposed to $\sqrt{t}$
+for a flux analysis, so a flux hint might be confirmed with an anisotropy
+signal. A first combined line search with Fermi-LAT would provide powerful new
+sensitivity; one with the proposed GAMMA-400 would be dramatically better.",1312.3945v1
+2013-12-28,Heavy Quark Diffusion in Strongly Coupled Anisotropic Plasmas,"We study the Langevin diffusion of a relativistic heavy quark in anisotropic
+strongly coupled theories in the local limit. Firstly, we use the axion
+space-dependent deformed anisotropic N=4 sYM, where the geometry anisotropy is
+always prolate, while the pressure anisotropy may be prolate or oblate. For
+motion along the anisotropic direction we find that the effective temperature
+for the quark can be larger than the heat bath temperature, in contrast to what
+happens in the isotropic theory. The longitudinal and transverse Langevin
+diffusion coefficients depend strongly on the anisotropy, the direction of
+motion and the transverse direction considered. We analyze the anisotropy
+effects to the coefficients and compare them to each other and to them of the
+isotropic theory. To examine the dependence of the coefficients on the type of
+the geometry, we consider another bottom-up anisotropic model. Changing the
+geometry from prolate to oblate, certain diffusion coefficients interchange
+their behaviors. In both anisotropic backgrounds we find cases that the
+transverse diffusion coefficient is larger than the longitudinal, but we find
+no negative excess noise.",1312.7474v1
+2014-01-04,Anisotropy of Conductivity in Bilayer Graphene with Relatively Shifted Layers,"A transformation of the band structure in bilayer graphene (BLG) with
+relatively shifted layers has been studied in the framework of the
+tight-binding model. BLG is demonstrated to remain a zero-gap material in the
+whole range of experimentally attainable shifts, but the positions of contact
+points between the conduction and valence bands depend substantially on the
+shift direction. The shift results in a considerable anisotropy of the band
+spectrum, which is, in turn, responsible for a substantial (10-20%) anisotropy
+of the conductivity in BLG. A possibility of using this anisotropy in
+high-sensitive sensors of a mechanical tension and for the generation of a
+purely valley current in multivalley anisotropic BLG in the case where both the
+average spin and the average current of electrons are equal to zero is
+discussed.",1401.0820v1
+2013-12-10,Anisotropy mapping in rat brains using Intermolecular Multiple Quantum Coherence Effects,"This document reports an unconventional and rapidly developing approach to
+magnetic resonance imaging (MRI) using intermolecular multiple-quantum
+coherences (iMQCs). Rat brain images are acquired using iMQCs. We detect iMQCs
+between spins that are 10 {\mu}m to 500 {\mu}m apart. The interaction between
+spins is dependent on different directions. We can choose the directions on
+physical Z, Y and X axis by choosing correlation gradients along those
+directions. As an important application, iMQCs can be used for anisotropy
+mapping. In the rat brains, we investigate tissue microstructure. We simulated
+images expected from rat brains without microstructure. We compare those with
+experimental results to prove that the dipolar field from the overall shape
+only has small contributions to the experimental iMQC signal. Because of the
+underlying low signal to noise ratio (SNR) in iMQCs, this anisotropy mapping
+method still has comparatively large potentials to grow. The ultimate goal of
+my project is to develop creative and effective methods of tissue
+microstructure anisotropy mapping. Recently we found that combining phase data
+of iMQCs images with phase data of modified-crazed images is very promising to
+construct microstructure maps. Some information and initial results are shown
+in this document.",1401.3772v1
+2014-01-21,Analysing the impact of anisotropy pressure on tokamak equilibria,"Neutral beam injection or ion cyclotron resonance heating induces pressure
+anisotropy. The axisymmetric plasma equilibrium code HELENA has been upgraded
+to include anisotropy and toroidal flow. With both analytical and numerical
+methods, we have studied the determinant factors in anisotropic equilibria and
+their impact on flux surfaces, magnetic axis shift, the displacement of
+pressures and density contours from flux surface. With $p_\parallel/p_\perp
+\approx 1.5$, $p_\perp$ can vary 20% on $s=0.5$ flux surface, in a MAST like
+equilibrium. We have also re-evaluated the widely applied approximation to
+anisotropy in which $p^*=(p_\parallel + p_\perp)/2$, the average of parallel
+and perpendicular pressure, is taken as the approximate isotropic pressure. We
+find the reconstructions of the same MAST discharge with $p_\parallel/p_\perp
+\approx 1.25$, using isotropic and anisotropic model respectively, to have a 3%
+difference in toroidal field but a 66% difference in poloidal current.",1401.5520v2
+2014-01-22,Sensitivity of orbiting JEM-EUSO to large-scale cosmic-ray anisotropies,"The two main advantages of space-based observation of extreme-energy
+($\gtrsim 10^{19}$~eV) cosmic-rays (EECRs) over ground-based observatories are
+the increased field of view, and the all-sky coverage with nearly uniform
+systematics of an orbiting observatory. The former guarantees increased
+statistics, whereas the latter enables a partitioning of the sky into spherical
+harmonics. We have begun an investigation, using the spherical harmonic
+technique, of the reach of \J\ into potential anisotropies in the
+extreme-energy cosmic-ray sky-map. The technique is explained here, and
+simulations are presented. The discovery of anisotropies would help to identify
+the long-sought origin of EECRs.",1401.5757v1
+2014-01-31,Phase diagram of the Hubbard model on the anisotropic triangular lattice,"We investigate the Hubbard model on the anisotropic triangular lattice as a
+suggested effective description of the Mott phase in various triangular organic
+compounds. Employing the variational cluster approximation and the ladder
+dual-fermion approach as complementary methods to adequately treat the
+zero-temperature and the finite-temperature domains, we obtain a consistent
+picture of the phase diagram as a function of anisotropy and interaction
+strength. The metal-insulator transition substantially depends on the
+anisotropy, and so does the nature of magnetism and the emergence of a
+nonmagnetic insulating phase. We further find that geometric anisotropy
+significantly influences the thermodynamics of the system. For increased
+frustration induced by anisotropy, the entropy of the system increases with
+interaction strength, opening the possibility of adiabatically cooling a
+frustrated system by an enhancement of electronic correlations.",1401.8198v3
+2014-02-04,Self-gravitating Newtonian models of fermions with anisotropy and cutoff energy in their distribution function,"Systems of self-gravitating fermions constitute a topic of great interest in
+astrophysics, due to the wide field of applications. In this paper, we consider
+the gravitational equilibrium of spherically symmetric Newtonian models of
+collisionless semidegenerate fermions. We construct numerical solutions by
+taking into account the effects of the anisotropy in the distribution function
+and considering the prevalence of tangential velocity. In this way, our models
+generalize the solutions obtained for isotropic Fermi-Dirac statistics. We also
+extend the analysis to equilibrium configurations in the classical regime and
+in the fully degenerate limit, recovering, for different levels of anisotropy,
+hollow equilibrium configurations obtained in Maxwellian regime. Moreover, in
+the limit of full degeneracy, we find a direct expression relating the
+anisotropy with the mass of the particles composing the system.",1402.0756v5
+2014-02-12,Magnetic anisotropy of thin sputtered MgB2 films on MgO substrates in high magnetic fields,"We investigated the magnetic anisotropy ratio of thin sputtered
+polycrystalline MgB2 films on MgO substrates. Using high magnetic field
+measurements, we estimated an anisotropy ratio of 1.35 for T=0 K with an upper
+critical field of 31.74 T in the parallel case and 23.5 T in the perpendicular
+case. Direct measurements of a magnetic-field sweep at 4.2 K show a linear
+behavior, confirmed by a linear fit for magnetic fields perpendicular to the
+film plane. Furthermore, we observed a change of up to 12% of the anisotropy
+ratio in dependence of the film thickness.",1402.2901v1
+2014-03-21,Anisotropy enhancement of the Casimir-Polder force between a nanoparticle and graphene,"We derive the analytical expressions for the thermal Casimir-Polder energy
+and force between a spheroidal nanoparticle above a semi-infinite material and
+a graphene covered interface. We analyze in detail the Casimir-Polder force
+between a gold nanoparticle and a single sheet of pristine graphene focusing on
+the impact of anisotropy. We show that the effect of anisotropy, i.e. the shape
+and orientation of the spheroidal nanoparticle, has a much larger influence on
+the force than the tunability of graphene. The effect of tuning and anisotropy
+both add up such that we observe a force which is between 20-50% of that in the
+ideal metal case which is much larger than the results found for the Casimir
+force between a metal halfspace and a layer of graphene.",1403.5476v2
+2014-03-28,Magnetic and structural properties of Co2FeAl thin films grown on Si substrate,"The correlation between magnetic and structural properties of Co_{2} FeAl
+(CFA) thin films of different thickness (10 nm<d< 100 nm) grown at room
+temperature on MgO-buffered Si/SiO2 substrates and annealed at
+600\lyxmathsym{\textdegree}C has been studied. XRD measurements revealed an
+(011) out-of-plane texture growth of the films. The deduced lattice parameter
+increases with the film thickness. Moreover, pole figures showed no in-plane
+preferential growth orientation. The magneto-optical Kerr effect hysteresis
+loops showed the presence of a weak in-plane uniaxial anisotropy with a random
+easy axis direction. The coercive field measured with an applied field along
+the easy axis direction and the uniaxial anisotropy field increase linearly
+with the inverse of the CFA thickness. The microstrip line ferromagnetic
+resonance measurements for in-plane and perpendicular applied magnetic fields
+revealed that the effective magnetization and the uniaxial in-palne anisotropy
+field follow a linear variation versus the inverse CFA thickness. This allows
+deriving a perpendicular surface anisotropy coefficient of -1.86 erg/cm2",1403.7566v1
+2014-04-22,Constituents of magnetic anisotropy and a screening of spin-orbit coupling in solids,"Using quantum mechanical perturbation theory (PT) we analyze how the energy
+of perturbation of different orders is renormalized in solids. We test the
+validity of PT analysis by considering a specific case of spin-orbit coupling
+as a perturbation. We further compare the relativistic energy and the magnetic
+anisotropy from the PT approach with direct density functional calculations in
+FePt, CoPt, FePd, MnAl, MnGa, FeNi, and tetragonally strained FeCo. In addition
+using decomposition of anisotropy into contributions from individual sites and
+different spin components we explain the microscopic origin of high anisotropy
+in FePt and CoPt magnets.",1404.5546v2
+2014-04-23,The role of the Galactic Halo and the Single Source in the formation of the cosmic ray anisotropy,"The existence of the cosmic ray Halo in our Galaxy has been discussed for
+more than half a century. If it is real it could help to explain some puzzling
+features of the cosmic ray flux: its small radial gradient, nearly perfect
+isotropy and the low level of the fine structure in the energy spectra of the
+various particles. All these features could be understood if: (a) the Halo has
+a big size (b) cosmic rays in the Halo have a unform spatial distribution and
+(c) the cosmic ray density in the Halo is comparable or even higher than that
+in the Galactic Disk. The main topic of the paper concerns the present status
+of the anisotropy and a model for its formation. In our model the extremely
+small amplitude of the dipole anisotropy is due to the dilution of the
+anisotropy in the Disk by the dominating isotropic cosmic rays from the Halo.
+Some minor deviations from complete isotropy in the sub-PeV and PeV energy
+regions point out to the possible contribution of the Single Source with the
+phase of its first harmonic opposite to the phase produced by the Disk.",1404.5918v1
+2014-04-28,Effect of anisotropy in the $S=1$ underscreened Kondo lattice,"We study the effect of crystal field anisotropy in the underscreened $S=1$
+Kondo lattice model. Starting from the two orbital Anderson lattice model and
+including a local anisotropy term, we show, through Schrieffer-Wolff
+transformation, that local anisotropy is equivalent to an anisotropic Kondo
+interaction ($J_{\parallel} \neq{J_{\perp}}$). The competition and coexistence
+between ferromagnetism and Kondo effect in this effective model is studied
+within a generalized mean-field approximation. Several regimes are obtained,
+depending on the parameters, exhibiting or not coexistence of magnetic order
+and Kondo effect. Particularly, we show that a re-entrant Kondo phase at low
+temperature can be obtained. We are also able to describe phases where the
+Kondo temperature is smaller than the Curie temperature ($T_K<T_C$). We propose
+that some aspects of uranium and neptunium compounds that present coexistence
+of Kondo effect and ferromagnetism, can be understood within this model.",1404.6864v1
+2014-05-05,Planar array of self-assembled Ga$_{x}$Fe$_{4-x}$N nanocrystals in GaN: Magnetic anisotropy determined via ferromagnetic resonance,"The magnetic anisotropy of a planar array of Ga$_{x}$Fe$_{4-x}$N nanocrystals
+(NCs) embedded in a GaN host is studied by ferromagnetic resonance. X-ray
+diffraction and transmission electron microscopy are employed to determine the
+phase and distribution of the nanocrystals. The magnetic anisotropy is found to
+be primarily uniaxial with the hard axis normal to the NCs plane and to have a
+comparably weak in-plane hexagonal symmetry. The origin of the magnetic
+anisotropy is discussed taking into consideration the morphology of the
+nanocrystals, the epitaxial relations, strain effects and magnetic coupling
+between the NCs.",1405.0906v2
+2014-05-09,Deformed Flux Tubes Produce Azimuthal Anisotropy in Heavy Ion Collisions,"We investigate the azimuthal anisotropy $v_2$ of particle production in
+nucleus-nucleus collisions in the maximum entropy approach. This necessitates
+two new phenomenological input parameters $\delta$ and $\lambda_2$ compared
+with integrated multiplicity distributions. The parameter $\delta$ describes
+the deformation of a flux tube and can be theoretically calculated in a bag
+model with a bag constant which depends on the density of surrounding flux
+tubes. The parameter $\lambda_2$ defines the anisotropy of the particle
+distribution in momentum space and can be connected to $\delta$ via the
+uncertainty relation. In this framework we compute the anisotropy $v_2$ as a
+function of centrality, transverse momentum and rapidity in qualitative
+agreement with LHC data.",1405.2248v2
+2014-05-09,Effect of equatorial line nodes on upper critical field and London penetration depth,"The upper critical field $H_{c2}$ and its anisotropy are calculated for order
+parameters with line nodes at equators, $k_z=0$, of the Fermi surface of
+uniaxial superconductors. It is shown that characteristic features found in
+Fe-based materials -- a nearly linear $H_{c2}(T)$ in a broad $T$ domain, a low
+and increasing on warming anisotropy $\gamma_H= H_{c2,ab}/ H_{c2,c}\, $ -- can
+be caused by competing effects of the equatorial nodes and of the Fermi surface
+anisotropy. For certain material parameters, $\gamma_H(T)-1$ may change sign on
+warming in agreement with recorded behavior of FeTeS system. It is also shown
+that the anisotropy of the penetration depth $\gamma_\lambda=
+\lambda_c/\lambda_{ab} $ decreases on warming to reach $\gamma_H$ at $T_c$ in
+agreement with data available. For some materials $\gamma_\lambda(T)$ may
+change on warming from $\gamma_\lambda>1$ at low $T$s to $\gamma_\lambda<1$ at
+high $T$s.",1405.2359v1
+2014-05-13,Constraining the Anisotropy of the Universe from Supernovae and Gamma-ray Bursts,"Recently, an anisotropic cosmological model was proposed. An arbitrary
+1-form, which picks out a privileged axis in the universe, was added to the
+Friedmann-Robertson-Walker line element. The distance-redshift relation was
+modified such that it is direction dependent. In this paper, we use the Union2
+dataset and 59 high-redshift gamma-ray bursts to give constraints on the
+anisotropy of the universe. The results show that the magnitude of anisotropy
+is about $D=-0.044\pm0.018$, and the privileged axis points towards the
+direction $(l_0,b_0)=(306.1^{\circ}\pm 18.7^{\circ},-18.2^{\circ}\pm
+11.2^{\circ})$ in the galactic coordinate system. The anisotropy is small and
+the isotropic cosmological model is an excellent approximation.",1405.3074v1
+2014-05-17,Application of the Enhanced Semidefinite Relaxation Method to Construction of the Optimal Anisotropy Function,"In this paper we propose and apply the enhanced semidefinite relaxation
+technique for solving a class of non-convex quadratic optimization problems.
+The approach is based on enhancing the semidefinite relaxation methodology by
+complementing linear equality constraints by quadratic-linear constrains. We
+give sufficient conditions guaranteeing that the optimal values of the primal
+and enhanced semidefinite relaxed problems coincide. We apply this approach to
+the problem of resolving the optimal anisotropy function. The idea is to
+construct an optimal anisotropy function as a minimizer for the anisotropic
+interface energy functional for a given Jordan curve in the plane. We present
+computational examples of resolving the optimal anisotropy function. The
+examples include boundaries of real snowflakes.",1405.4382v3
+2014-06-02,CMB $μ$ distortion from primordial gravitational waves,"We propose a new mechanism of generating the $\mu$ distortion in cosmic
+microwave background (CMB) originated from primordial gravitational waves. Such
+$\mu$ distortion is generated by the damping of the temperature anisotropies
+through the Thomson scattering, even on scales larger than that of Silk
+damping. This mechanism is in sharp contrast with that from the primordial
+curvature (scalar) perturbations, in which the temperature anisotropies mainly
+decay by Silk damping effects. We estimate the size of the $\mu$ distortion
+from the new mechanism, which can be used to constrain the amplitude of
+primordial gravitational waves on smaller scales independently from the CMB
+anisotropies, giving more wide-range constraint on their spectral index by
+combining the amplitude from the CMB anisotropies.",1406.0451v2
+2014-06-26,Spin-torque diode radio-frequency detector with voltage tuned resonance,"We report on a voltage tunable radio-frequency (RF) detector based on a
+magnetic tunnel junction (MTJ). The spin-torque diode effect is used to excite
+and/or detect RF oscillations in the magnetic free layer of the MTJ. In order
+to reduce the overall in-plane magnetic anisotropy of the free layer, we take
+advantage of the perpendicular magnetic anisotropy at the interface between
+ferromagnetic and insulating layers. The applied bias voltage is shown to have
+a significant influence on the magnetic anisotropy, and thus on the resonance
+frequency of the device. This influence also depends on the voltage polarity.
+The obtained results are accounted for in terms of the interplay of
+spin-transfer-torque and voltage-controlled magnetic anisotropy effects.",1406.6935v1
+2014-07-01,Measuring Anisotropies in the Cosmic Neutrino Background,"Neutrino capture on tritium has emerged as a promising method for detecting
+the cosmic neutrino background (CvB). We show that relic neutrinos are captured
+most readily when their spin vectors are anti-aligned with the polarization
+axis of the tritium nuclei and when they approach along the direction of
+polarization. As a result, CvB observatories may measure anisotropies in the
+cosmic neutrino velocity and spin distributions by polarizing the tritium
+targets. A small dipole anisotropy in the CvB is expected due to the peculiar
+velocity of the lab frame with respect to the cosmic frame and due to late-time
+gravitational effects. The PTOLEMY experiment, a tritium observatory currently
+under construction, should observe a nearly isotropic background. This would
+serve as a strong test of the cosmological origin of a potential signal. The
+polarized-target measurements may also constrain non-standard neutrino
+interactions that would induce larger anisotropies and help discriminate
+between Majorana versus Dirac neutrinos.",1407.0393v1
+2014-07-20,Probing Transverse Magnetic Anisotropy by Electronic Transport through a Single-Molecule Magnet,"By means of electronic transport, we study the transverse magnetic anisotropy
+of an individual Fe$_4$ single-molecule magnet (SMM) embedded in a
+three-terminal junction. In particular, we determine in situ the transverse
+anisotropy of the molecule from the pronounced intensity modulations of the
+linear conductance, which are observed as a function of applied magnetic field.
+The proposed technique works at temperatures exceeding the energy scale of the
+tunnel splittings of the SMM. We deduce that the transverse anisotropy for a
+single Fe$_4$ molecule captured in a junction is substantially larger than the
+bulk value.",1407.5265v2
+2014-07-28,Collective effects in light-heavy ion collisions,"We present results for the azimuthal anisotropy of charged hadron
+distributions in A+A, p+A, d+A, and He3+A collisions within the IP-Glasma+MUSIC
+model. Obtained anisotropies are due to the fluid dynamic response of the
+system to the fluctuating initial geometry of the interaction region. While the
+elliptic and triangular anisotropies in peripheral Pb+Pb collisions at
+root-s=2.76 TeV are well described by the model, the same quantities in
+root-s=5.02 TeV p+Pb collisions underestimate the experimental data. This
+disagreement can be due to neglected initial state correlations or the lack of
+a detailed description of the fluctuating spatial structure of the proton, or
+both. We further present predictions for azimuthal anisotropies in p+Au, d+Au,
+and He3+Au collisions at root-s=200 GeV. For d+Au and 3He+Au collisions we
+expect the detailed substructure of the nucleon to become less important.",1407.7557v1
+2014-08-07,Ferromagnetic resonance of a magnetic dimer with dipolar coupling,"We develop a general formalism for analyzing the ferromagnetic resonance
+characteristics of a magnetic dimer consisting of two magnetic elements (in a
+horizontal or vertical configuration) coupled by dipolar interaction, taking
+account of their finite-size and aspect ratio. We study the effect on the
+resonance frequency and resonance field of the applied magnetic field (in
+amplitude and direction), the inter-element coupling, and the uniaxial
+anisotropy in various configurations. We obtain analytical expressions for the
+resonance frequency in various regimes of the interlayer coupling. We
+(numerically) investigate the behavior of the resonance field in the
+corresponding regimes. The critical value of the applied magnetic field at
+which the resonance frequency vanishes may be an increasing or a decreasing
+function of the dimer's coupling, depending on the anisotropy configuration. It
+is also a function of the nanomagnets aspect ratio in the case of in-plane
+anisotropy. This and several other results of this work, when compared with
+experiments using the standard ferromagnetic resonance with fixed frequency, or
+the network analyzer with varying frequency and applied magnetic field, provide
+a useful means for characterizing the effective anisotropy and coupling within
+systems of stacked or assembled nanomagnets.",1408.1594v1
+2014-08-07,Tuning Perpendicular Anisotropy Gradient in Co/Pd Multilayers by Ion Irradiation,"The tunability of Ar+ ion irradiation of Co/Pd multilayers has been employed
+to create depth-dependent perpendicular anisotropy gradients. By adjusting the
+Ar+ kinetic energy and fluence, the depth and lateral density of the local
+structural modification are controlled. First-order reversal curve analysis
+through X-ray magnetic circular dichroism and conventional magnetometry studies
+show that the local structural damage weakens the perpendicular anisotropy near
+the surface, leading to a magnetization tilting towards the in-plane direction.
+The ion irradiation method is complementary to, and may be used in conjunction
+with, other synthesis approaches to maximize the anisotropy gradient.",1408.1659v1
+2014-08-13,Temperature-Dependent Interplay of Dzyaloshinskii-Moriya Interaction and Single-Ion Anisotropy in Multiferroic BiFeO$_3$,"Low-energy magnon excitations in multiferroic BiFeO$_3$ were measured in
+detail as a function of temperature around several Brillouin zone centers by
+inelastic neutron scattering experiments on single crystals. Unique features
+around 1 meV are directly associated with the interplay of the
+Dzyaloshinskii-Moriya interaction and a small single-ion anisotropy. The
+temperature dependence of these and the exchange interactions were determined
+by fitting the measured magnon dispersion with spin-wave calculations. The
+spectra best fits an easy-axis type magnetic anisotropy and the deduced
+exchange and anisotropy parameters enable us to determine the anharmonicity of
+the magnetic cycloid. We then draw a direct connection between the changes in
+the parameters of spin Hamiltonian with temperature and the physical properties
+and structural deformations of BiFeO$_3$.",1408.2942v2
+2014-09-09,Most spin-1/2 transition-metal ions do have single ion anisotropy,"The cause for the preferred spin orientation in magnetic systems containing
+spin-1/2 transition-metal ions was explored by studying the origin of the
+easy-plane anisotropy of the spin-1/2 Cu2+ ions in CuCl2.2H2O, LiCuVO4, CuCl2
+and CuBr2 on the basis of density functional theory and magnetic dipole-dipole
+energy calculations as well as a perturbation theory treatment of the
+spin-orbit coupling. We find that the spin orientation observed for these
+spin-1/2 ions is not caused by their anisotropic spin exchange interactions,
+nor by their magnetic dipole-dipole interactions, but by the spin-orbit
+coupling associated with their crystal-field split d-states. Our study also
+predicts in-plane anisotropy for the Cu2+ ions of Bi2CuO4 and Li2CuO2. The
+results of our investigations dispel the mistaken belief that magnetic systems
+with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.",1409.2795v2
+2014-10-15,Low artificial anisotropy cellular automaton model and its applications to the cell-to-dendrite transition in directional solidification,"A low artificial anisotropy cellular automaton (CA) model is developed for
+the simulation of microstructure evolution in directional solidification. The
+CA model's capture rule was modified by a limited neighbor solid fraction
+(LNSF) method. Various interface curvature calculation methods have been
+compared. The simulated equilibrium shapes agree with the theoretical shapes,
+when the interface energy anisotropy coefficient is {\epsilon}=0.01,
+{\epsilon}=0.03 and {\epsilon}=0.05, respectively.The low artificial anisotropy
+CA model is used in the numerical simulation of the cell-to-dendrite transition
+(CDT) in directional solidification. The influence of physical parameters
+({\Gamma}, Dl, k0, ml) on CDT has been investigated. The main finding in this
+paper is the discovery of the changing behavior of the Vcd when the solute
+partition coefficient k0 is larger than a critical value. When k0 is less than
+0.125, the Vcd follows the Kurz and Fisher criterion Vc/k0; while when
+k0>0.125, the Vcd equals to 8Vc. The experimental data of
+succinonitrile-acetone (SCN-ace, k0=0.1) and SCN-camphor (k0=0.33) support the
+conclusion from CA simulations.",1410.3907v1
+2014-10-21,Anisotropic fluid star model in isotropic coordinates,"We present a spherically symmetric solution of the general relativistic field
+equations in isotropic coordinates for anisotropic neutral fluid, compatible
+with a super dense star modeling by considering a specific choice of anisotropy
+factor that includes a positive constant defined as anisotropy parameter, which
+varies the relation between the radial and tangential pressure. Further, we
+have constructed a super-dense star model with all degree of suitability. We
+have found that the maximum mass decreases with the increase of anisotropy
+parameter. The robustness of our result is that it matches with the recent
+discoveries.",1410.5808v1
+2014-11-03,Curvature effects in statics and dynamics of low dimensional magnets,"We develop an approach to treat magnetic energy of a ferromagnet for
+arbitrary curved wires and shells on the assumption that the anisotropy
+contribution much exceeds the dipolar and other weak interactions. We show that
+the curvature induces two effective magnetic interactions: effective magnetic
+anisotropy and effective Dzyaloshinskii-like interaction. We derive an equation
+of magnetisation dynamics and propose a general static solution for the limit
+case of strong anisotropy. To illustrate our approach we consider the
+magnetisation structure in a ring wire and a cone surface: ground states in
+both systems essentially depend on the curvature excluding strictly tangential
+solutions even in the case of strong anisotropy. We derive also the spectrum of
+spin waves in such systems.",1411.0646v2
+2014-11-26,Electrical manipulation of orbital occupancy and magnetic anisotropy in manganites,"Electrical manipulation of lattice, charge, and spin has been realized
+respectively by the piezoelectric effect, field-effect transistor, and electric
+field control of ferromagnetism, bringing about dramatic promotions both in
+fundamental research and industrial production. However, it is generally
+accepted that the orbital of materials are impossible to be altered once they
+have been made. Here we use electric-field to dynamically tune the electronic
+phase transition in (La,Sr)MnO3 films with different Mn^4+/(Mn^3+ + Mn^4+)
+ratios. The orbital occupancy and corresponding magnetic anisotropy of these
+thin films are manipulated by gate voltage in a reversible and quantitative
+manner. Positive gate voltage increases the proportion of occupancy of the
+orbital and magnetic anisotropy that were initially favored by strain
+(irrespective of tensile and compressive), while negative gate voltage reduces
+the concomitant preferential orbital occupancy and magnetic anisotropy. Besides
+its fundamental significance in orbital physics, our findings might advance the
+process towards practical oxide-electronics based on orbital.",1411.7128v1
+2014-12-18,Scaling of Coercivity in a 3d Random Anisotropy Model,"The random-anisotropy Heisenberg model is numerically studied on lattices
+containing over ten million spins. The study is focused on hysteresis and
+metastability due to topological defects, and is relevant to magnetic
+properties of amorphous and sintered magnets. We are interested in the limit
+when ferromagnetic correlations extend beyond the size of the grain inside
+which the magnetic anisotropy axes are correlated. In that limit the coercive
+field computed numerically roughly scales as the fourth power of the random
+anisotropy strength and as the sixth power of the grain size. Theoretical
+arguments are presented that provide an explanation of numerical results. Our
+findings should be helpful for designing amorphous and nanosintered materials
+with desired magnetic properties.",1412.6182v1
+2014-12-23,The Anisotropy of the Extragalactic Radio Background from Dark Matter Annihilation,"Observations of the extragalactic radio background have uncovered a
+significant isotropic emission across multiple frequencies spanning from 22 MHz
+to 10 GHz. The intensity of this non-thermal emission component significantly
+exceeds the expected contribution from known astrophysical sources.
+Interestingly, models have indicated that the annihilation of dark matter
+particles may reproduce both the flux and spectrum of the excess. However, the
+lack of a measurable anisotropy in the residual emission remains challenging
+for both dark matter and standard astrophysical interpretations of the ARCADE-2
+data. We calculate the expected synchrotron anisotropy from dark matter
+annihilation and show that these models can produce very small anisotropies,
+though this requires galaxy clusters to have large substructure contributions
+and strong magnetic fields. We show that this constraint can be significantly
+relaxed, however, in scenarios where electrons produced via dark matter
+annihilation can be efficiently reaccelerated by Alfv\'en waves in the
+intra-Cluster medium. Our analysis indicates that any source capable of
+explaining the intensity and isotropy of the extragalactic radio excess must
+have a spatial extension far larger than typical for baryons in galaxies,
+suggesting a novel physics interpretation.",1412.7545v1
+2015-01-05,Reversed anisotropy of the in-plane resistivity in the antiferromagnetic phase of iron tellurides,"We systematically investigated the anisotropic in-plane resistivity of the
+iron telluride including three kinds of impurity atoms: excess Fe, Se
+substituted for Te, and Cu substituted for Fe. Sizable resistivity anisotropy
+was found in the magneto-structurally ordered phase whereas the sign is
+opposite ($\rho_a$ $>$ $\rho_b$, where the $b$-axis parameter is shorter than
+the $a$-axis one) to that observed in the transition-metal doped iron arsenides
+($\rho_a$ $<$ $\rho_b$). On the other hand, our results demonstrate that the
+magnitude of the resistivity anisotropy in the iron tellurides is correlated
+with the amount of impurities, implying that the resistivity anisotropy
+originates from an exotic impurity effect like that in the iron arsenides. This
+suggests that the anisotropic carrier scattering by impurities is a universal
+phenomenon in the magneto-structurally ordered phase of the iron-based
+materials.",1501.00774v1
+2015-01-14,Dilepton production from the quark-gluon plasma using (3+1)-dimensional anisotropic dissipative hydrodynamics,"We compute dilepton production from the deconfined phase of the quark-gluon
+plasma using leading-order (3+1)-dimensional anisotropic hydrodynamics. The
+anisotropic hydrodynamics equa- tions employed describe the full spatiotemporal
+evolution of the transverse temperature, spheroidal momentum-space anisotropy
+parameter, and the associated three-dimensional collective flow of the matter.
+The momentum-space anisotropy is also taken into account in the computation of
+the dilepton production rate, allowing for a self-consistent description of
+dilepton production from the quark-gluon plasma. For our final results, we
+present predictions for high-energy dilepton yields as a function of invariant
+mass, transverse momentum, and pair rapidity. We demonstrate that high- energy
+dilepton production is extremely sensitive to the assumed level of initial
+momentum-space anisotropy of the quark-gluon plasma. As a result, it may be
+possible to experimentally constrain the early-time momentum-space anisotropy
+of the quark-gluon plasma generated in relativistic heavy ion collisions using
+high-energy dilepton yields.",1501.03418v1
+2015-01-21,Universal distribution of magnetic anisotropy of impurities in ordered and disordered nano-grains,"We examine the distribution of the magnetic anisotropy (MA) experienced by a
+magnetic impurity embedded in a metallic nano-grain. As an example of a generic
+magnetic impurity with partially filled $d$-shell, we study the case of $d^{1}$
+impurities imbedded into ordered and disordered Au nano-grains, described in
+terms of a realistic band structure. Confinement of the electrons induces a
+magnetic anisotropy that is large, and can be characterized by 5 real
+parameters, coupling to the quadrupolar moments of the spin. In ordered
+(spherical) nano-grains, these parameters exhibit symmetrical structures and
+reflect the symmetry of the underlying lattice, while for disordered grains
+they are randomly distributed and, - for stronger disorder, - their
+distribution is found to be characterized by random matrix theory. As a result,
+the probability of having small magnetic anisotropies $K_L$ is suppressed below
+a characteristic scale $\Delta_E$, which we predict to scale with the number of
+atoms $N$ as $\Delta_E\sim 1/N^{3/2}$. This gives rise to anomalies in the
+specific heat and the susceptibility at temperatures $T\sim \Delta_E$ and
+produces distinct structures in the magnetic excitation spectrum of the
+clusters, that should be possible to detect experimentally.",1501.05346v1
+2015-02-23,Can modified gravity models reconcile the tension between CMB anisotropy and lensing maps in Planck-like observations?,"Planck-2015 data seem to favour a large value of the lensing amplitude
+parameter, $A_{\rm L}=1.22\pm0.10$, in CMB spectra. This result is in $2\sigma$
+tension with the lensing reconstruction result, $A_{\rm
+L}^{\phi\phi}=0.95\pm0.04$. In this paper, we simulate several CMB anisotropy
+and CMB lensing spectra based on Planck-2015 best-fit cosmological parameter
+values and Planck blue book beam and noise specifications. We analyse several
+modified gravity models within the effective field theory framework against
+these simulations and find that models whose effective Newton constant is
+enhanced can modulate the CMB anisotropy spectra in a way similar to that of
+the $A_{\rm L}$ parameter. However, in order to lens the CMB anisotropies
+sufficiently, like in the Planck-2015 results, the growth of matter
+perturbations is substantially enhanced and gives a high $\sigma_8$ value. This
+in turn proves to be problematic when combining these data to other probes,
+like weak lensing from CFHTLenS, that favour a smaller amplitude of matter
+fluctuations.",1502.06599v1
+2015-03-09,"Alternating magnetic anisotropy of Li$_2$(Li$_{1-x}T_x$)N with $T$ = Mn, Fe, Co, and Ni","Substantial amounts of the transition metals Mn, Fe, Co, and Ni can be
+substituted for Li in single crystalline Li$_2$(Li$_{1-x}T_x$)N. Isothermal and
+temperature-dependent magnetization measurements reveal local magnetic moments
+with magnitudes significantly exceeding the spin-only value. The additional
+contributions stem from unquenched orbital moments that lead to rare-earth-like
+behavior of the magnetic properties. Accordingly, extremely large magnetic
+anisotropies have been found. Most notably, the magnetic anisotropy alternates
+as easy-plane $\rightarrow$ easy-axis $\rightarrow$ easy-plane $\rightarrow$
+easy-axis when progressing from $T$ = Mn $\rightarrow$ Fe $\rightarrow$ Co
+$\rightarrow$ Ni. This behavior can be understood based on a perturbation
+approach in an analytical, single-ion model. The calculated magnetic
+anisotropies show a surprisingly good agreement with the experiment and capture
+the basic features observed for the different transition metals.",1503.02501v2
+2015-04-04,Design of Black Phosphorus 2D Nanomechanical Resonators by Exploiting the Intrinsic Mechanical Anisotropy,"Black phosphorus (P), a layered material that can be isolated down to
+individual 2D crystalline sheets, exhibits highly anisotropic mechanical
+properties due to its corrugated crystal structure in each atomic layer, which
+are intriguing for 2D nanomechanical devices. Here we lay the framework for
+describing the mechanical resonant responses in free-standing black P
+structures, by using a combination of analytical modeling and numerical
+simulation. We find that thicker devices (>100nm) operating in the elastic
+plate regime exhibit pronounced signatures of mechanical anisotropy, and can
+lead to new multimode resonant characteristics in terms of mode sequences,
+shapes, and orientational preferences that are unavailable in nanomechanical
+resonators made of isotropic materials. In addition, through investigating
+devices with different geometries, we identify the resonant response's
+dependence on crystal orientation in asymmetric devices, and evaluate the
+effects from the degree of anisotropy. The results suggest a pathway towards
+harnessing the mechanical anisotropy in black P for building novel 2D
+nanomechanical devices and resonant transducers with engineerable multimode
+functions.",1504.01060v1
+2015-04-10,Influence of magnetic surface anisotropy on spin wave reflection from the edge of ferromagnetic film,"We study propagation of the Gaussian beam of spin waves and its reflection
+from the edge of thin yttrium-iron-garnet film with in-plane magnetization
+perpendicular to this edge. We have performed micromagnetic simulations
+supported by analytical calculations to investigate influence of the surface
+magnetic anisotropy present at the film edge on the reflection, especially in
+the context of the Goos-Hanchen effect. We have shown the appearance of a
+negative lateral shift between reflected and incident spin wave beams' spots.
+This shift is particularly sensitive to the surface magnetic anisotropy value
+and is a result of the Goos-Hanchen shift which is sensitive to the magnitude
+of the anisotropy and of the bending of spin wave beam. We have demonstrated
+that the demagnetizing field provide graded increase of the refractive index
+for spin waves, which is responsible for the bending.",1504.02668v2
+2015-04-26,Origin of the resistive anisotropy in the electronic nematic phase of BaFe$_2$As$_2$ revealed by optical spectroscopy,"We perform, as a function of uniaxial stress, an optical-reflectivity
+investigation of the representative 'parent' ferropnictide BaFe$_2$As$_2$ in a
+broad spectral range, across the tetragonal-to-orthorhombic phase transition
+and the onset of the long-range antiferromagnetic order (AFM). The infrared
+response reveals that the $dc$ transport anisotropy in the orthorhombic AFM
+state is determined by the interplay between the Drude spectral weight and the
+scattering rate, but that the dominant effect is clearly associated with the
+metallic spectral weight. In the paramagnetic tetragonal phase, though, the
+$dc$ resistivity anisotropy of strained samples is almost exclusively due to
+stress-induced changes in the Drude weight rather than in the scattering rate,
+definitively establishing the anisotropy of the Fermi surface parameters as the
+primary effect driving the $dc$ transport properties in the electronic nematic
+state.",1504.06829v1
+2015-05-05,In-plane transport anisotropy in BSCCO-Ag multi-filamentary tapes,"Composite structures such as High-Tc multi-filamentary tapes display a
+complex anisotropy arising from the combination of the intrinsic anisotropy of
+the Bi-2223 grains, and that associated to the superconducting phase
+distribution in the superconductor-metal composite, as well as cracks and other
+defects. In this paper we characterize the in-plane anisotropy of BSCCO-Ag
+tapes, i.e., the difference between the transport properties along the
+longitudinal axis and those along the transverse direction also lying on the
+wide face of the tape. In particular, we demonstrate that the dissipation
+associated to transport along the transverse direction approaches that of the
+longitudinal direction as the temperature or the current increase, which may be
+relevant to transport applications in situations where the superconducting
+properties have significantly degraded.",1505.01190v1
+2015-05-13,The electronic origin of shear-induced direct to indirect gap transition and anisotropy diminution in phosphorene,"Artificial monolayer black phosphorus, the so-called phosphorene has
+attracted global interest with its distinguished anisotropic optoelectronic and
+electronic properties. Here, we unraveled the shear-induced direct to indirect
+gap transition and anisotropy diminution in phosphorene based on
+first-principles calculations. Lattice dynamic analysis demonstrated that
+phosphorene can sustain up to 10% applied shear strain. The band gap of
+phosphorene experiences a direct to indirect transition when 5% shear strain is
+applied. The electronic origin of direct to indirect gap transition from 1.54
+eV at ambient condition to 1.22 eV at 10% shear strains for phosphorene was
+explored and the anisotropy diminution in phosphorene is discussed by
+calculating the maximum sound velocities, effective mass and decomposed charge
+density, which signals the undesired shear-induced direct to indirect gap
+transition in the applications of phosphorene for electronics and
+optoelectronics. On the other hand, the shear-induced electronic anisotropy
+properties suggest that phosphorene can be applied as the switcher in the nano
+electronic applications.",1505.03353v1
+2015-06-17,Small-Scale Anisotropies of Cosmic Rays from Relative Diffusion,"The arrival directions of multi-TeV cosmic rays show significant anisotropies
+at small angular scales. It has been argued that this small-scale structure can
+naturally arise from cosmic ray scattering in local turbulent magnetic fields
+that distort a global dipole anisotropy set by diffusion. We study this effect
+in terms of the power spectrum of cosmic ray arrival directions and show that
+the strength of small-scale anisotropies is related to properties of relative
+diffusion. We provide a formalism for how these power spectra can be inferred
+from simulations and motivate a simple analytic extension of the
+ensemble-averaged diffusion equation that can account for the effect.",1506.05488v2
+2015-06-19,Statistics of the CMB polarised anisotropies,"This PhD thesis (defended in 2014) is focused on the estimation of the CMB
+polarised anisotropies power spectra on a masked sky and on forecasts of
+constraints set on the primordial universe physics thanks to these
+anisotropies. After an introduction on the light polarisation, the standard
+model of cosmology and the CMB properties, I show the results obtained on the
+use and efficiency of pseudospectrum methods to correct for the so-called
+E-to-B leakage. Afterwards, I present the forecasts obtained on the detection
+of the tensor-to-scalar ratio r and on the detection of chiral gravity, using
+the pure pseudospectrum method. The study of forecasts of a primordial magnetic
+field detection using the CMB polarised anisotropies is finally briefly
+tackled.",1506.05940v1
+2015-06-25,Dirac electrons and domain walls: a realization in junctions of ferromagnets and topological insulators,"We study a system of Dirac electrons with finite density of charge carriers
+coupled to an external electromagnetic field in two spatial dimensions, with a
+domain wall (DW) mass term. The interface between a thin-film ferromagnet and a
+three-dimensional topological insulator provides a condensed-matter realization
+of this model, when an out-of-plane domain wall magnetization is coupled to the
+TI surface states. We show how, for films with very weak intrinsic in-plane
+anisotropies, the torque generated by the edge electronic current flowing along
+the DW competes with an effective in-plane anisotropy energy, induced by
+quantum fluctuations of the chiral electrons bound to the wall, in a mission to
+drive the internal angle of the DW from a Bloch configuration towards a N\'eel
+configuration. Both the edge current and the induced anisotropy contribute to
+stabilize the internal angle, so that for weak intrinsic in-plane anisotropies
+DW motion is still possible without suffering from an extremely early Walker
+breakdown.",1506.07668v1
+2015-07-19,Fabrication of Flexible Oriented Magnetic Thin Films with Large in-plane Uniaxial Anisotropy by Roll-to-roll Nanoimprint Lithography,"Here, we report wafer scale fabrication of densely packed Fe nanostripe-based
+magnetic thin films on a flexible substrate and their magnetic anisotropy
+properties. We find that Fe nanostripes exhibit large in-plane uniaxial
+anisotropy and nearly square hysteresis loops with energy products (BH)max
+exceeding 3 MGOe at room temperature. High density Fe nanostripes were
+fabricated on 70 nm flexible polyethylene terephthalate (PET) gratings, which
+were made by roll-to-roll (R2R) UV nanoimprintlithography technique. Observed
+large in-plane uniaxial anisotropies along the long dimension of nanostripes
+are attributed to the shape. Temperature dependent hysteresis measurements
+confirm that the magnetization reversal is driven by non-coherent rotation
+reversal processes.",1507.05252v1
+2015-07-23,Anisotropies of ultra-high energy cosmic ray nuclei diffusing from extragalactic sources,"We obtain the dipolar anisotropies in the arrival directions of ultra-high
+energy cosmic ray nuclei diffusing from nearby extragalactic sources. We
+consider mixed-composition scenarios in which different cosmic ray nuclei are
+accelerated up to the same maximum rigidity, so that $E<ZE_\text{max}^p$, with
+$Z$ the atomic number and $E_\text{max}^p$ the maximum proton energy. We adopt
+$E_\text{max}^p\simeq 6$ EeV so as to account for an increasingly heavier
+composition above the ankle. We obtain the anisotropies through Monte Carlo
+simulations that implement the cosmic ray diffusion in extragalactic turbulent
+fields as well as the effects of photo-disintegrations and other energy losses.
+Dipolar anisotropies at the level of 5 to 10\% at energies $\sim 10$~EeV are
+predicted for plausible values of the source density and magnetic fields.",1507.06585v1
+2015-08-19,Observation of Anisotropy in the Arrival Direction Distribution of TeV Cosmic Rays with HAWC,"The High-Altitude Water Cherenkov (HAWC) Observatory, located 4100 m above
+sea level near Sierra Negra (19$^\circ$ N) in Mexico, is sensitive to gamma
+rays and cosmic rays at TeV energies. The arrival direction distribution of
+cosmic rays at these energies shows significant anisotropy on several angular
+scales, with a relative intensity ranging between 10$^{-3}$ and 10$^{-4}$. We
+present the results of a study of cosmic-ray anisotropy based on more than 86
+billion cosmic-ray air showers recorded with HAWC since June 2013. The HAWC
+cosmic-ray sky map, which has a median energy of 2 TeV, exhibits several
+regions of significantly enhanced cosmic-ray flux. We present the energy
+dependence of the anisotropy and the cosmic-ray spectrum in the regions of
+significant excess.",1508.04781v1
+2015-08-31,Edge-modulated perpendicular magnetic anisotropy in [Co/Pd]n and L10-FePt thin film wires,"Thickness modulation at the edges of nanostructured magnetic thin films is
+shown to have important effects on their perpendicular magnetic anisotropy.
+Thin film wires with tapered edges were made from [Co/Pd]20 multilayers or
+L10-FePt films using liftoff with a double layer resist. The effect of edge
+taper on the reversal process was studied using magnetic force microscopy and
+micromagnetic modeling. In [Co/Pd]20 the anisotropy was lower in the tapered
+edge regions which switched at a lower reverse field compared to the center of
+the wire. The L10-FePt wires showed opposite behavior with the tapered regions
+exhibiting higher anisotropy.",1508.07948v2
+2015-09-03,Magnetic alignment of block copolymer microdomains by intrinsic chain anisotropy,"We examine the role of intrinsic chain susceptibility anisotropy in magnetic
+field directed self-assembly of a block copolymer using \textit{in situ} X-ray
+scattering. Alignment of a lamellar mesophase is observed on cooling across the
+disorder-order transition with the resulting orientational order inversely
+proportional to the cooling rate. We discuss the origin of the susceptibility
+anisotropy, $\Delta\chi$, that drives alignment, and calculate its magnitude
+using coarse-grained molecular dynamics to sample conformations of
+surface-tethered chains, finding $\Delta\chi\approx 2\times10^{-8}$. From
+field-dependent scattering data we estimate grains of $\approx1.2$ $\mu$m are
+present during alignment. These results demonstrate that intrinsic anisotropy
+is sufficient to support strong field-induced mesophase alignment and suggest a
+versatile strategy for field control of orientational order in block
+copolymers.",1509.01292v1
+2015-09-22,Long-lived Neel states in antiferromagnetic quantum spin chains with strong uniaxial anisotropy for atomic-scale antiferromagnetic spintronics,"It has been experimentally established that magnetic adatoms on surfaces can
+be arranged to form antiferromagnetic quantum spin chains with strong uniaxial
+anisotropy and Neel states in such spin systems can be used to realize
+information storage. Here, we investigate eigen states, quantum spin dynamics,
+and life times of Neel states in short antiferromagnetic quantum spin chains
+with strong uniaxial anisotropy on the basis of numerical exact diagonalization
+method. We show rigorously that as long as the uniaxial anisotropy is very
+strong, the ground state and the first excitation state, being nearly
+degenerate, are safely separated from the other states and thus dominate the
+quantum dynamics of the Neel states. Through further numerical analysis, we
+achieve a powerful life-time expression of the Neel states for arbitrary spin
+and model parameters. It is interesting that for the famous Fe adatom chains on
+Cu$_2$N surface, 14 or 16 Fe adatoms are enough to obtain a practical long
+life-time for Neel state storage of information. These should be applicable to
+other similar antiferromagnetic spin systems for atomic-scale antiferromagnetic
+spintronics.",1509.06597v1
+2015-10-20,Monte Carlo Simulations of ABC Stacked Kagome Lattice Thin Films,"Properties of thin films of geometrically frustrated ABC stacked
+antiferromagnetic kagome layers are examined using Metropolis Monte Carlo
+simulations. The impact of having an easy-axis anisotropy on the surface layers
+and cubic anisotropy in the interior layers is explored. The spin structure at
+the surface is shown to be different from that of the bulk 3D fcc system, where
+surface axial anisotropy tends to align spins along the surface [111] normal
+axis. This alignment tendency then propagates only weakly to the interior
+layers through exchange coupling. Results are shown for the specific heat,
+magnetization and sub-lattice order parameters for both surface and interior
+spins in three and six layer films as a function of increasing axial surface
+anisotropy. Relevance to the exchange bias phenomenon in IrMn$_3$ thin films is
+discussed.",1510.05924v1
+2015-10-31,"Investigating the anisotropic scintillation response in anthracene through neutron, gamma-ray, and muon measurements","This paper reports a series of measurements that characterize the directional
+dependence of the scintillation response of crystalline anthracene to incident
+DT neutrons, DD neutrons, Cs-137 gamma rays, and, for the first time, cosmic
+ray muons. The neutron measurements give the amplitude and pulse shape
+dependence on the proton recoil direction over one hemisphere of the crystal,
+confirming and extending previous results in the literature. In similar
+measurements using incident gamma rays, no directional effect is evident, and
+any anisotropy with respect to the electron recoil direction is constrained to
+have a magnitude of less than a tenth of that present in the proton recoil
+events. Cosmic muons are measured at two directions, and no anisotropy is
+observed. This set of observations indicates that high dE/dx is necessary for
+an anisotropy to be present for a given type of scintillation event, which in
+turn could be used to discriminate among different hypotheses for the
+underlying causes of the anisotropy, which are not well understood.",1511.00081v1
+2015-12-08,Orbital anisotropy underlying the superconducting dome in BaFe$_2$(As$_{1-x}$P$_x$)$_2$ superconductors,"We investigate the in-plane anisotropy of Fe 3d orbitals occurring in a wide
+temperature and composition range of BaFe2(As1-xPx)2 system. By employing the
+angle-resolved photoemission spectroscopy, the lifting of degeneracy in dxz and
+dyz orbitals at the Brillouin zone corners can be obtained as a measure of the
+orbital anisotropy. In the underdoped regime, it starts to evolve on cooling
+from high temperatures above both antiferromagnetic and orthorhombic
+transitions. With increasing x, it well survives into the superconducting
+regime, but gradually gets suppressed and finally disappears around the
+non-superconducting transition (x = 0.7). The observed spontaneous in-plane
+orbital anisotropy, possibly coupled with anisotropic lattice and magnetic
+fluctuations, implies the rotational-symmetry broken electronic state working
+as the stage for the superconductivity in BaFe2(As1-xPx)2.",1512.02389v1
+2015-12-11,A new method for testing isotropy with Shannon entropy,"We propose a novel method for testing isotropy of a three-dimensional
+distribution using Shannon entropy. We test the method on some Monte Carlo
+simulations of isotropic and anisotropic distributions and find that the method
+can effectively identify and characterize different types of hemispherical
+asymmetry inputted in a distribution. We generate anisotropic distributions by
+introducing pockets of different densities inside homogeneous and isotropic
+distributions and find that the proposed method can effectively quantify the
+degree of anisotropy and determine the geometry of the pockets introduced. We
+also considered spherically symmetric radially inhomogeneous distributions
+which are anisotropic at all points other than the centre and find that such
+anisotropy can be easily characterized by our method. We use a semi analytic
+galaxy catalogue from the Millennium simulation to study the anisotropies
+induced by the redshift space distortions and find that the method can separate
+such anisotropies from a general one. The method may be also suitably adapted
+for any two dimensional maps on the celestial sphere to study the hemispherical
+asymmetry in other cosmological observations.",1512.03562v2
+2015-12-16,"On the existence conditions of surface spin wave modes in (Ga,Mn)As thin films","Spin-wave resonance (SWR) is a newly emerged method for studying surface
+magnetic anisotropy and surface spin-wave modes (SSWMs) in (Ga,Mn)As thin
+films. The existence of SSWMs in (Ga,Mn)As thin films has recently been
+reported in the literature; SSWMs have been observed in the in-plane
+configuration (with variable azimuth angle $\phi_M$ between the in-plane
+magnetization of the film and the surface [100] crystal axis), in the azimuth
+angle range between two in-plane critical angles $\phi_{c1}$ and $\phi_{c2}$.
+We show here that cubic surface anisotropy is an essential factor determining
+the existence conditions of the above-mentioned SSWMs: conditions favorable for
+the occurrence of surface spin-wave modes in a (Ga,Mn)As thin film in the
+in-plane configuration are fulfilled for those azimuth orientations of the
+magnetization of the sample that lie around the hard axes of cubic magnetic
+anisotropy. This implies that a hard cubic anisotropy axis can be regarded in
+(Ga,Mn)As thin films as an easy axis for surface spin pinning.",1512.05140v1
+2016-01-06,Strain-assisted magnetization reversal in Co/Ni multilayers with perpendicular magnetic anisotropy,"Multifunctional materials composed of ultrathin magnetic films with
+perpendicular magnetic anisotropy combined with ferroelectric substrates
+represent a new approach toward low power, fast, high density spintronics. Here
+we demonstrate Co/Ni multilayered films with tunable saturation magnetization
+and perpendicular anisotropy grown directly on ferroelectric PZT
+[Pb(Zr_xTi_1-x)O_3] substrate plates. Electric fields up to +/- 2 MV/m expand
+the PZT by 0.1% and generate at least 0.02% in-plane compression in the Co/Ni
+multilayered film. Modifying the strain with a voltage can reduce the coercive
+field by over 30%. We also demonstrate that alternating in-plane tensile and
+compressive strains (less than 0.01%) can be used to propagate magnetic domain
+walls. This ability to manipulate high anisotropy magnetic thin films could
+prove useful for lowering the switching energy for magnetic elements in future
+voltage-controlled spintronic devices.",1601.01349v1
+2016-01-12,Ultrafast magneto-photocurrents as probe of anisotropy relaxation in GaAs,"We induce ultrafast photocurrents in a GaAs crystal exposed to a magnetic
+field by optical femtosecond excitation. The magneto-photocurrents are studied
+by time-resolved detection of the simultaneously emitted THz radiation. We find
+that their dynamics differ considerably from the dynamics of other
+photocurrents which are expected to follow the temporal shape of the optical
+intensity. We attribute this difference to the influence of carrier-anisotropy
+relaxation on the magneto-photocurrents. Our measurements show that the
+anisotropy relaxation for carrier densities ranging between $10^{16}$ cm$^{-3}$
+and $5 \times 10^{17}$ cm$^{-3}$ occurs on two different time scales. While the
+slow time constant is approximately 100 fs long and most likely governed by
+electron-phonon scattering, the fast time constant is on the order of 10 fs and
+presumably linked to the valence band. Our studies not only help to better
+understand the microscopic origins of optically induced currents but - being
+even more important - show that magneto-photocurrents can be employed as novel
+probe of anisotropy relaxation in GaAs. This technique is applicable to all
+non-centrosymmetric bulk semiconductors.",1601.02962v1
+2016-01-25,"Fermi surfaces, spin-mixing parameter, and colossal anisotropy of spin relaxation in transition metals from ab initio theory","The Fermi-surfaces and Elliott-Yafet spin-mixing parameter (EYP) of several
+elemental metals are studied by \emph{ab initio} calculations. We focus first
+on the anisotropy of the EYP as a function of the direction of the
+spin-quantization axis [Phys.~Rev.~Lett.\ \textbf{109}, 236603 (2012)]. We
+analyze in detail the origin of the gigantic anisotropy in $5d$ hcp metals as
+compared to $5d$ cubic metals by band-structure calculations and discuss the
+stability of our results against an applied magnetic field. We further present
+calculations of light (4$d$ and 3$d$) hcp crystals, where we find a huge
+increase of the EYP anisotropy, reaching colossal values as large as $6000\%$
+in hcp Ti. We attribute these findings to the reduced strength of spin-orbit
+coupling, which promotes the anisotropic spin-flip hot loops at the Fermi
+surface.
+  In order to conduct these investigations, we developed an adapted
+tetrahedron-based method for the precise calculation of Fermi surfaces of
+complicated shape and accurate Fermi-surface integrals within the
+full-potential relativistic Korringa-Kohn-Rostoker Green-function method.",1601.06605v1
+2016-02-23,Impact of momentum anisotropy and turbulent chromo-fields on thermal particle production in quark-gluon plasma medium,"Momentum anisotropy present during the hydrodynamic evolution of Quark-Gluon
+Plasma (QGP) in RHIC may lead to chromo-Weibel instability and turbulent
+chromo-fields.The dynamics of the quark and gluon momentum distributions in
+this case is governed by an effective diffusive Vlasov equation (linearized).
+The solution of this linearized transport equation for the modified momentum
+distribution functions lead to the mathematical form of non-equilibrium
+momentum distribution functions of quarks/antiquarks and gluons. The
+modification to these distributions encode the physics of turbulent color
+fields and momentum anisotropy. In the present manuscript, we employ these
+distribution functions to to estimate thermal dilepton production rate in the
+QGP medium. The production rate is seen to have appreciable sensitivity to the
+strength of the anisotropy.",1602.07142v3
+2016-03-02,Blocking temperature of interacting magnetic nanoparticles with uniaxial and cubic anisotropies from Monte Carlo simulations,"The low temperature behavior of densely packed interacting spherical single
+domain nanoparticles (MNP) is investigated by Monte Carlo simulations in the
+framework of an effective one spin model. The particles are distributed through
+a hard sphere like distribution with periodic boundary conditions and interact
+through the dipole dipole interaction (DDI) with an anisotropy energy including
+both cubic and uniaxial symmetry components. The cubic component is shown to
+play a sizable role on the value of the blocking temperature $T_b$ only when
+the MNP easy axes are parallel to the cubic easy direction ([111] direction for
+a negative cubic anisotropy constant). The nature of the collective low
+temperature state, either ferromagnetic or spin glass like, is found to depend
+on the ratio of the anisotropy to the dipolar energies characterizing partly
+the disorder in the system.",1603.00605v1
+2016-03-11,A Mechanism of Long-Range Order Induced by Random Local Fields: Effective Anisotropy Created by Defects,"We propose a microscopic mechanism of the long-range order in two-dimensional
+space induced by random local fields of crystal defects. The anisotropic
+distribution of defect-induced random local field directions in the
+n-dimensional space of vector order parameter with the O(n) symmetry is shown
+to give rise to the defect-induced effective anisotropy in the system. The
+expression for the effective anisotropy constant is found. A weak anisotropy of
+the ""easy axis"" type transforms the X-Y model and the Heisenberg model to the
+class of Ising models, and brings into existence the long-range order in the
+system.",1603.03687v1
+2016-03-20,Reconstruction of CMB Temperature Anisotropies with Primordial CMB Induced Polarization in Galaxy Clusters,"Scattering of cosmic microwave background (CMB) radiation in galaxy clusters
+induces polarization signals determined by the quadrupole anisotropy in the
+photon distribution at the location of clusters. This ""remote quadrupole""
+derived from the measurements of the induced polarization in galaxy clusters
+provides an opportunity of reconstruction of local CMB temperature
+anisotropies. In this {\em Letter} we develop an algorithm of the
+reconstruction through the estimation of the underlying primordial
+gravitational potential, which is the origin of the CMB temperature and
+polarization fluctuations and CMB induced polarization in galaxy clusters. We
+found a nice reconstruction for the quadrupole and octopole components of the
+CMB temperature anisotropies with the assistance of the CMB induced
+polarization signals. The reconstruction can be an important consistency test
+on the puzzles of CMB anomaly, especially for the low quadrupole and axis of
+evil problems reported in WMAP and Planck data.",1603.06166v1
+2016-04-01,Conductivities in an anisotropic medium,"In order to imitate anisotropic medium of a condensed matter system, we take
+into account an Einstein-Maxwell-dilaton-axion model as a dual gravity theory
+where the anisotropy is caused by different momentum relaxations. This gravity
+model allows an anisotropic charged black hole solution. On this background, we
+investigate how the linear responses of vector modes like electric,
+thermoelectric, and thermal conductivities rely on the anisotropy. We find that
+the electric conductivity in low frequency limit shows a Drude peak and that in
+the intermediate frequency regime it reveals the power law behavior.
+Especially, when the anisotropy increases the exponent of the power law becomes
+smaller. In addition, we find that there exist a critical value for the
+anisotropy at which the DC conductivity reaches to its maximum value.",1604.00156v1
+2016-04-23,Interplay between anisotropy and spatial dispersion in metamaterial waveguide,"We analyze spectrum of waveguide modes of an arbitrary uniaxial anisotropic
+metamaterial slab with non-local electromagnetic response whose permittivity
+tensor could be described within Drude approximation. Spatial dispersion was
+introduced within the hydrodynamical model. Both anisotropy and spatial
+dispersion were considered as perturbations. This helps to distinguish their
+effect on the spectrum of the slab and to analyze lifting of the degeneracy of
+eigenmodes at plasma frequency in detail. Spatial dispersion is shown to result
+in break of the singularity in the den- sity of optical states in the
+hyperbolic regime and in suppression of negative dispersion induced by
+anisotropy. Mutual effect of spatial dispersion and anisotropy can bring light
+to a complete stop at certain frequencies.",1604.06925v1
+2016-05-02,A computational scheme to evaluate Hamaker constants of molecules with practical size and anisotropy,"We propose a computational scheme to evaluate Hamaker constants, $A$, of
+molecules with practical sizes and anisotropies. Upon the increasing
+feasibility of diffusion Monte Carlo (DMC) methods to evaluate binding curves
+for such molecules to extract the constants, we discussed how to treat the
+averaging over anisotropy and how to correct the bias due to the
+non-additivity. We have developed a computational procedure for dealing with
+the anisotropy and reducing statistical errors and biases in DMC valuations,
+based on possible validations on predicted $A$. We applied the scheme to
+cyclohexasilane molecule, Si$_6$H$_{12}$, used in 'printed electronics'
+fabrications, getting $A \sim 105 \pm 2$ [zJ], being in plausible range
+supported even by other possible extrapolations. The scheme provided here would
+open a way to use handy {\it ab initio} evaluations to predict wettabilities as
+in the form of materials informatics over broader molecules.",1605.00580v3
+2016-05-10,Latent heat at the first order phase transition point of SU(3) gauge theory,"We calculate the energy gap (latent heat) and pressure gap between the hot
+and cold phases of the SU(3) gauge theory at the first order deconfining phase
+transition point. We perform simulations around the phase transition point with
+the lattice size in the temporal direction Nt=6, 8 and 12 and extrapolate the
+results to the continuum limit. We also investigate the spatial volume
+dependence. The energy density and pressure are evaluated by the derivative
+method with non-perturabative anisotropy coefficients. We adopt a multi-point
+reweighting method to determine the anisotropy coefficients. We confirm that
+the anisotropy coefficients approach the perturbative values as Nt increases.
+We find that the pressure gap vanishes at all values of Nt when the
+non-perturbative anisotropy coefficients are used. The spatial volume
+dependence in the latent heat is found to be small on large lattices.
+Performing extrapolation to the continuum limit, we obtain $ \Delta
+\epsilon/T^4 = 0.75 \pm 0.17 $ and $ \Delta (\epsilon -3 p)/T^4 = 0.623 \pm
+0.056.$",1605.02997v1
+2016-05-11,Anisotropy of spin coherence in high mobility quantum wells with arbitrary magnetic fields,"We present a theoretical study of the anisotropy of the spin relaxation and
+decoherence in typical quantum wells with an arbitrary magnetic field. In such
+systems, the orientation of the magnetic field relative to the main
+crystallographic directions is crucial, owing to the lack of spin-rotation
+symmetry. For typical high mobility samples, relaxation anisotropies in the
+motional narrowing limit owing to the interplay of Rashba and Dresselhaus spin
+orbit coupling are calculated. We also include the effect of the
+cubic-in-momentum terms. Although commonly ignored in literature, the latter
+were experimentally evidenced by the observation of strong anisotropy in spin
+decoherence measurements by different experimental groups and has long remained
+unexplained.",1605.03399v2
+2016-05-25,Linear theory of random textures of 3He-A in aerogel,"Spacial variation of the orbital part of the order parameter of $^3$He-A in
+aerogel is represented as a random walk of the unit vector $\mathbf{l}$ in a
+field of random anisotropy produced by the strands of aerogel. For a range of
+distances, where variation of $\mathbf{l}$ is small in comparison with its
+absolute value correlation function of directions of $\mathbf{l}(\mathbf{r})$
+is expressed in terms of the correlation function of the random anisotropy
+field. With simplifying assumptions about this correlation function a spatial
+dependence of the average variation $\langle\delta\mathbf{l}^2\rangle$ is found
+analytically for isotropic and axially anisotropic aerogels. Average
+projections of $\mathbf{l}$ on the axes of anisotropy are expressed in terms of
+characteristic parameters of the problem. Within the ""model of random
+cylinders"" numerical estimations of characteristic length for disruption of the
+long-range order and of the critical anisotropy for restoration of this order
+are made and compared with other estimations .",1605.07828v3
+2016-07-24,Morphology dependent optical anisotropies in the n-type polymer P(NDI2OD-T2),"Organic semiconductors tend to self-assemble into highly ordered and oriented
+morphologies with anisotropic optical properties. Studying these optical
+anisotropies provides insight into processing-dependent structural properties
+and informs the photonic design of organic photovoltaic and light-emitting
+devices. Here, we measure the anisotropic optical properties of spin-cast films
+of the n-type polymer P(NDI2OD-T2) using momentum-resolved absorption and
+emission spectroscopies. We quantify differences in the optical anisotropies of
+films deposited with distinct face-on and edge-on morphologies. In particular,
+we infer a substantially larger out-of-plane tilt angle of the optical
+transition dipole moment in high temperature annealed, edge-on films.
+Measurements of spectral differences between in-plane and out-of-plane dipoles,
+further indicate regions of disordered polymers in low temperature annealed
+face-on films that are otherwise obscured in traditional X-ray and optical
+characterization techniques. The methods and analysis developed in this work
+provide a way to identify and quantify subtle optical and structural
+anisotropies in organic semiconductors that are important for understanding and
+designing highly efficient thin film devices.",1607.07066v1
+2016-08-24,Anisotropic spin fluctuations in Sr$_2$RuO$_4$: role of spin-orbit coupling and induced strain,"We analyze the spin anisotropy of the magnetic susceptibility of Sr$_2$RuO$4$
+in presence of spin-orbit coupling and anisotropic strain using
+quasi-two-dimensional tight-binding parametrization fitted to the ARPES
+results. Similar to the previous observations we find the in-plane polarization
+of the low ${\bf q}$ magnetic fluctuations and the out-of-plane polarization of
+the incommensurate magnetic fluctuation at the nesting wave vector ${\bf Q}_1 =
+(2/3 \pi ,2/3 \pi)$ but also nearly isotropic fluctuations near ${\bf
+Q}_2=(\pi/6,\pi/6)$. Furthermore, one finds that apart from the high-symmetry
+direction of the tetragonal Brillouin zone the magnetic anisotropy is maximal,
+i.e. $\chi^{xx} \neq \chi^{yy} \neq \chi^{zz}$. This is the consequence of the
+orbital anisotropy of the $xz$ and $yz$ orbitals in the momentum space. We also
+study how the magnetic anisotropy evolves in the presence of the strain and
+find strong Ising-like ferromagnetic fluctuations near the Lifshitz transition
+for the $xy$-band.",1608.06786v1
+2016-09-25,Resolving and Tuning Mechanical Anisotropy in Black Phosphorus via Nanomechanical Multimode Resonance Spectromicroscopy,"Black phosphorus (P) has emerged as a layered semiconductor with a unique
+crystal structure featuring corrugated atomic layers and strong in-plane
+anisotropy in its physical properties. Here, we demonstrate that the crystal
+orientation and mechanical anisotropy in free-standing black P thin layers can
+be precisely determined by spatially resolved multimode nanomechanical
+resonances. This offers a new means for resolving important crystal orientation
+and anisotropy in black P device platforms in situ beyond conventional optical
+and electrical calibration techniques. Furthermore, we show that
+electrostatic-gating-induced straining can continuously tune the mechanical
+anisotropic effects on multimode resonances in black P electromechanical
+devices. Combined with finite element modeling (FEM), we also determine the
+Young's moduli of multilayer black P to be 116.1 and 46.5 GPa in the zigzag and
+armchair directions, respectively.",1609.07801v1
+2016-09-26,Ferromagnetic resonance study of composite Co/Ni - FeCoB free layers with perpendicular anisotropy,"We study the properties of composite free layers with perpendicular
+anisotropy. The free layers are made of a soft FeCoB layer ferromagnetically
+coupled by a variable spacer (Ta, W, Mo) to a very anisotropic [Co/Ni]
+multilayer embodied in a magnetic tunnel junction meant for spin torque memory
+applications. For this we use broadband ferromagnetic resonance to follow the
+field dependence of the acoustical and optical excitation of the composite free
+layer in both in-plane and out-of-plane applied fields. The modeling provides
+the interlayer exchange coupling, the anisotropies and the damping factors. The
+popular Ta spacer are outperformed by W and even more by Mo, which combines the
+strongest interlayer exchange coupling without sacrificing anisotropies,
+damping factors and transport properties.",1609.07863v1
+2016-09-26,Supernovae anisotropy power spectrum,"We contribute another anisotropy study to this field of research using Type
+Ia supernovae (SNe Ia). In this work, we utilise the power spectrum calculation
+method and apply it to both the current SNe Ia data and simulation. Using the
+Union2.1 data set at all redshifts, we compare the spectrum of the residuals of
+the observed distance moduli to that expected from an isotropic universe
+affected by the Union2.1 observational uncertainties at low multipoles. Through
+this comparison we find a dipolar anisotropy with tension of less that
+$2\sigma$ towards $l =171^\circ \pm 21^\circ$ and $b=-26^\circ \pm 28^\circ$
+which is mainly induced by anisotropic spatial distribution of the SNe with $z
+> 0.2$ rather than being a cosmic effect. Furthermore, we find a tension of
+$\sim 4\sigma$ at $\ell=4$ between the two spectra. Our simulations are
+constructed with the characteristics of the upcoming surveys like the Large
+Synoptic Survey Telescope (LSST), which shall bring us the largest SNe Ia
+collection to date. We make predictions for the amplitude of a possible dipolar
+anisotropy that would be detectable by future SNe Ia surveys.",1609.08012v3
+2016-10-10,Determination of the resistivity anisotropy of orthorhombic materials via transverse resistivity measurements,"Measurements of the resistivity anisotropy can provide crucial information
+about the electronic structure and scattering processes in anisotropic and
+low-dimensional materials, but quantitative measurements by conventional means
+often suffer very significant systematic errors. Here we describe a novel
+approach to measuring the resistivity anisotropy of orthorhombic materials,
+using a single crystal and a single measurement, that is derived from a
+$\frac{\pi}{4}$ rotation of the measurement frame relative to the
+crystallographic axes. In this new basis the transverse resistivity gives a
+direct measurement of the resistivity anisotropy, which combined with the
+longitudinal resistivity also gives the in-plane elements of the conventional
+resistivity tensor via a 5-point contact geometry. This is demonstrated through
+application to the charge-density wave compound ErTe$_3$, and it is concluded
+that this method presents a significant improvement on existing techniques in
+many scenarios.",1610.03122v1
+2016-10-19,Anomalous Thermal Diffusivity in Underdoped YBa$_2$Cu$_3$O$_{6+x}$,"We present local optical measurements of thermal diffusivity in the $ab$
+plane of underdoped YBCO crystals. We find that the diffusivity anisotropy is
+comparable to reported values of the electrical resistivity anisotropy,
+suggesting that the anisotropies have the same origin. The anisotropy drops
+sharply below the charge order transition. We interpret our results through a
+strong electron-phonon scattering picture and find that both electronic and
+phononic contributions to the diffusivity saturate a proposed bound. Our
+results suggest that neither well-defined electron nor phonon quasiparticles
+are present in this material.",1610.05845v2
+2016-10-27,Giant variation of the perpendicular magnetic anisotropy at Fe/MgO interfaces by oxygen migration: a first-principles study,"A characteristic dependence of voltage control of perpendicular magnetic
+anisotropy (VCMA) on oxygen migration at Fe/MgO interfaces was revealed by
+performing systematic {\it ab initio} study of the energetics of the oxygen
+path around the interface. We find that the surface anisotropy energy exhibits
+a Boltzmann sigmoidal behavior as a function of the migrated O-atoms
+concentration. The obtained variation of the VCMA efficiency factor $\beta$
+reveals a saturation limit beyond a critical concentration of migrated O, about
+$54\%$, at which the anisotropy switches from perpendicular to in plane.
+Furthermore, depending on the range of variation of the applied voltage, two
+regimes associated with reversible or irreversible ions displacement are
+predicted to occur, yielding different VCMA response. According to our
+findings, one can distinguish from the order of magnitude of $\beta$ the VCMA
+driving mechanism: an effect of several tens of fJ/(V.m) is likely associated
+to charge-mediated effect combined with slight reversible oxygen displacements
+whereas an effect of the order of thousands of fJ/(V.m) is more likely
+associated with irreversible oxygen ionic migration.",1610.08859v2
+2016-11-15,Recent progress in anisotropic hydrodynamics,"The quark-gluon plasma created in a relativistic heavy-ion collisions
+possesses a sizable pressure anisotropy in the local rest frame at very early
+times after the initial nuclear impact and this anisotropy only slowly relaxes
+as the system evolves. In a kinetic theory picture, this translates into the
+existence of sizable momentum-space anisotropies in the underlying partonic
+distribution functions, <p_L^2> << <p_T^2>. In such cases, it is better to
+reorganize the hydrodynamical expansion by taking into account momentum-space
+anisotropies at leading-order in the expansion instead of as a perturbative
+correction to an isotropic distribution. The resulting anisotropic
+hydrodynamics framework has been shown to more accurately describe the dynamics
+of rapidly expanding systems such as the quark-gluon plasma. In this
+proceedings contribution, I review the basic ideas of anisotropic
+hydrodynamics, recent progress, and present a few preliminary phenomenological
+predictions for identified particle spectra and elliptic flow.",1611.05056v1
+2016-11-25,Flow anisotropy due to momentum deposition in ultra-relativistic nuclear collisions,"Minijets and jets are produced in large numbers in nuclear collisions at TeV
+energies, so that there are many of them in a single fireball. They deposit
+non-negligible amount of momentum and energy into the hydrodynamically
+expanding bulk and cause anisotropies of the expansion. Moreover, due to their
+multiple production in a single event the resulting anisotropies are correlated
+with the collision geometry and thus contribute positively also to
+event-averaged anisotropies in non-central collisions. Using simulations with
+three-dimensional ideal hydrodynamic model we demonstrate the importance of
+this effect. It must be taken into account if conclusions about the properties
+of the hot matter are to be drawn.",1611.08577v1
+2016-11-28,Fine-tuning challenges for the matter bounce scenario,"A bouncing universe with a long period of contraction during which the
+average density is pressureless (the same equation of state as matter) as
+cosmologically observable scales exit the Hubble horizon has been proposed as
+an explanation for producing a nearly scale-invariant spectrum of adiabatic
+scalar perturbations. A well-known problem with this scenario is that, unless
+suppressed, the energy density associated with anisotropy grows faster than
+that of the pressureless matter, so the matter-like phase is unstable. Previous
+models introduce an ekpyrotic phase after the matter-like phase to prevent the
+anisotropy from generating chaotic mixmaster behavior. In this work, though, we
+point out that, unless the anisotropy is suppressed first, the matter-like
+phase will never start and that suppressing the anisotropy requires
+extraordinary, exponential fine-tuning.",1611.08972v1
+2016-12-07,Size-Resolved Photoelectron Anisotropy of Gas Phase Water Clusters and Predictions for Liquid Water,"We report the first measurement of size-resolved photoelectron angular
+distributions for the valence orbitals of water clusters with up to 20
+molecules. A systematic decrease of the photoelectron anisotropy is found for
+clusters with up to 5-6 molecules, and most remarkably, convergence of the
+anisotropy for larger clusters. We suggest the latter to be the result of a
+local short-range scattering potential that is fully described by a unit of 5-6
+molecules. The cluster data and a detailed electron scattering model are used
+to predict liquid water anisotropies. Reasonable agreement with experimental
+liquid jet data is found.",1612.02338v1
+2017-01-16,Electric field modulation of the non-linear areal magnetic anisotropy energy,"We study the ferromagnetic layer thickness dependence of the
+voltage-controlled magnetic anisotropy (VCMA) in gated CoFeB/MgO
+heterostructures with heavy metal underlayers. When the effective CoFeB
+thickness is below ~1 nm, the VCMA efficiency of Ta/CoFeB/MgO heterostructures
+considerably decreases with decreasing CoFeB thickness. We find that a high
+order phenomenological term used to describe the thickness dependence of the
+areal magnetic anisotropy energy can also account for the change in the areal
+VCMA efficiency. In this structure, the higher order term competes against the
+common interfacial VCMA, thereby reducing the efficiency at lower CoFeB
+thickness. The areal VCMA efficiency does not saturate even when the effective
+CoFeB thickness exceeds ~1 nm. We consider the higher order term is related to
+the strain that develops at the CoFeB/MgO interface: as the average strain of
+the CoFeB layer changes with its thickness, the electronic structure of the
+CoFeB/MgO interface varies leading to changes in areal magnetic anisotropy
+energy and VCMA efficiency.",1701.04150v1
+2017-01-26,Numerical study of anisotropy in a composite Fermi liquid,"We perform density-matrix renormalization group studies of a two-dimensional
+electron gas in a high magnetic field and with an anisotropic band mass. At
+half-filling in the lowest Landau level, such a system is a Fermi liquid of
+composite fermions. By measuring the Fermi surface of these composite fermions,
+we determine a relationship between the anisotropy of composite fermion
+dispersion, $\alpha_{CF}$, and the original anisotropy $\alpha_F$ of the
+fermion dispersion at zero magnetic field. For systems where the electrons
+interact via a Coulomb interaction, we find $\alpha_{CF}=\sqrt{\alpha_F}$
+within our numerical accuracy. The same result has been found concurrently in
+recent experiments. We also show results with other forms of the
+electron-electron interaction; this allows us (a) to benchmark our procedure
+against known exact results and (b) to show that the relationship between the
+anisotropies is dependent on the form of the interaction.",1701.07832v2
+2017-01-16,Bianchi-V String Cosmological model with Dark Energy Anisotropy,"The role of anisotropic components on the dark energy and the dynamics of the
+universe is investigated. An anisotropic dark energy fluid with different
+pressures along different spatial directions is assumed to incorporate the
+effect of anisotropy. One dimensional cosmic strings aligned along x-direction
+supplement some kind of anisotropy. Anisotropy in the dark energy pressure is
+found to evolve with cosmic expansion at least at late times. At an early
+phase, the anisotropic effect due to the cosmic strings substantially affect
+the dynamics of the accelerating universe.",1701.08632v4
+2017-02-02,Radial anisotropy in omega Cen limiting the room for an intermediate-mass black hole,"Finding an intermediate-mass black hole (IMBH) in a globular cluster (or
+proving its absence) would provide valuable insights into our understanding of
+galaxy formation and evolution. However, it is challenging to identify a unique
+signature of an IMBH that cannot be accounted for by other processes.
+Observational claims of IMBH detection are indeed often based on analyses of
+the kinematics of stars in the cluster core, the most common signature being a
+rise in the velocity dispersion profile towards the centre of the system.
+Unfortunately, this IMBH signal is degenerate with the presence of
+radially-biased pressure anisotropy in the globular cluster. To explore the
+role of anisotropy in shaping the observational kinematics of clusters, we
+analyse the case of omega Cen by comparing the observed profiles to those
+calculated from the family of LIMEPY models, that account for the presence of
+anisotropy in the system in a physically motivated way. The best-fit radially
+anisotropic models reproduce the observational profiles well, and describe the
+central kinematics as derived from Hubble Space Telescope proper motions
+without the need for an IMBH.",1702.00725v1
+2017-02-03,Cosmic-Ray Anisotropy and the Local Interstellar Turbulence,"We study the role of local interstellar turbulence in shaping the large-scale
+anisotropy in the arrival directions of TeV-PeV cosmic-rays (CRs) on the sky.
+Assuming pitch-angle diffusion of CRs in a magnetic flux tube containing the
+Earth, we compute the CR anisotropy for Goldreich-Sridhar turbulence, and for
+isotropic fast modes. The narrow deficits in the 400 TeV and 2 PeV data sets of
+IceTop can be fitted for some parameters of the turbulence. The data also rule
+out a part of the parameter space. The shape of the CR anisotropy may be used
+as a local probe of the still poorly known properties of the interstellar
+turbulence and of CR transport.",1702.01001v1
+2017-02-12,"Micromagnetic study of a feasibility of the magnetic anisotropy engineering in nano-structured epitaxial films of (III,Mn)V ferromagnetic semiconductors","The attainability of modification of the apparent magnetic anisotropy in
+(III,Mn)V ferromagnetic semiconductors is probed by means of the
+finite-elements-based modelling. The most representative case of (Ga,Mn)As and
+its in-plane uniaxial anisotropy is investigated. The hysteresis loops of the
+continuous films of a ferromagnetic semiconductor as well as films structured
+with the elliptic antidots are modelled for various eccentricity, orientation,
+and separation of the anti dots. The effect of anti-dots on the magnetic
+anisotropy is confirmed but overall is found to be very weak. The subsequent
+modelling for (Ga,Mn)As film with the elliptic dots comprising of metallic NiFe
+shows much stronger effect, revealing switching of the magnetic moment in the
+ferromagnetic semiconductor governed by the switching behavior of the metallic
+inclusions.",1702.03509v1
+2017-02-12,Excitonic mass gap in uniaxially strained graphene,"We study the conditions for spontaneously generating an excitonic mass gap
+due to Coulomb interactions between anisotropic Dirac fermions in uniaxially
+strained graphene. The mass gap equation is realized as a self-consistent
+solution for the self-energy within the Hartree-Fock mean-field and static
+random phase approximations. It depends not only on momentum, due to the
+long-range nature of the interaction, but also on the velocity anisotropy
+caused by the presence of uniaxial strain. We solve the nonlinear integral
+equation self-consistently by performing large scale numerical calculations on
+variable grid sizes. We evaluate the mass gap at the charge neutrality (Dirac)
+point as a function of the dimensionless coupling constant and anisotropy
+parameter. We also obtain the phase diagram of the critical coupling, at which
+the gap becomes finite, against velocity anisotropy. Our numerical study
+indicates that with an increase in uniaxial strain in graphene the strength of
+critical coupling decreases, which suggests anisotropy supports formation of
+excitonic mass gap in graphene.",1702.03551v2
+2017-03-21,Experimental determination of Rashba and Dresselhaus parameters and $g^*$-factor anisotropy via Shubnikov-de Haas oscillations,"The spin splitting of conduction band electrons in inversion-asymmetric
+InGaAs/InP quantum wells is studied by Shubnikov-de Haas measurements combining
+the analysis of beating patterns and coincidence measurements in doubly tilted
+magnetic fields. The method allows us to determine the absolute values of the
+Rashba and linear Dresselhaus spin-orbit interaction coefficients, their
+relative sign and the full Land\'e g-tensor. This is achieved by analyzing the
+anisotropy of the beat node positions with respect to both polar and azimuthal
+angles between the magnetic field direction and the quantum well normal. We
+show that the spin-orbit interaction is dominated by a large Rashba coefficient
+together with a linear Dresselhaus coefficient that is 10 $\%$ of the Rashba
+coefficient. Their relative sign is found to be positive. The g-tensor is found
+to have a marked out-of-plane anisotropy and a smaller but distinct in-plane
+anisotropy due to spin-orbit interaction.",1703.07143v1
+2017-03-23,Effect of anisotropy distribution on local nucleation field in bistable ferromagntic microwires,"Critical parameters defining the local nucleation field in amorphous
+ferromagnetic microwires with positive magnetostriction are obtained
+analytically through scaling procedures. Exact value of the nucleation field is
+obtained numerically as a function of geometric parameters of anisotropy
+distribution, which is fully taken into account instead of being averaged out.
+It is established that the value of nucleation field depends predominantly on
+the steepness of anisotropy change withing the boundary between axial and
+radial domains, while the maximal value of anisotropy inside the wire or an
+overall average is not relevant.",1703.08066v5
+2017-04-10,Limits on statistical anisotropy from BOSS DR12 galaxies using bipolar spherical harmonics,"We measure statistically anisotropic signatures imprinted in
+three-dimensional galaxy clustering using bipolar spherical harmonics (BipoSHs)
+in both Fourier space and configuration space. We then constrain a well-known
+quadrupolar anisotropy parameter $g_{2M}$ in the primordial power spectrum,
+parametrized by $P(\vec{k}) = \bar{P}(k) [ 1 + \sum_{M} g_{2M} Y_{2M}(\hat{k})
+]$, with $M$ determining the direction of the anisotropy. Such an anisotropic
+signal is easily contaminated by artificial asymmetries due to specific survey
+geometry. We precisely estimate the contaminated signal and finally subtract it
+from the data. Using the galaxy samples obtained by the Baryon Oscillation
+Spectroscopic Survey Data Release 12, we find no evidence for violation of
+statistical isotropy, $g_{2M}$ for all $M$ to be of zero within the $2\sigma$
+level. The $g_{2M}$-type anisotropy can originate from the primordial curvature
+power spectrum involving a directional-dependent modulation $g_* (\hat{k} \cdot
+\hat{p})^2$. The bound on $g_{2M}$ is translated into $g_*$ as $-0.09 < g_* <
+0.08$ with a $95\%$ confidence level when $\hat{p}$ is marginalized over.",1704.02868v2
+2017-04-18,Heavy decaying dark matter and large-scale anisotropy of high-energy cosmic rays,"We examine the role of the large--scale anisotropy of the high--energy cosmic
+ray distribution in a search for the heavy decaying dark matter (DM) signal.
+Using recent anisotropy measurements from the extensive air shower (EAS)
+observatories we constrain the lifetime of the DM particles with masses
+$10^{7}~\leq~M_X~\leq~10^{16}$ GeV. These constraints appear to be weaker than
+that obtained with the high energy gamma-ray limits. We also estimate the
+desired precision level for the anisotropy measurements to discern the decaying
+DM signal marginally allowed by the gamma-ray limits and discuss the prospects
+of the DM search with the modern EAS facilities.",1704.05300v2
+2017-04-18,Instability constraints for the electron temperature anisotropy in the slow solar wind. Thermal core vs. suprathermal halo,"This letter presents the results of an advanced parametrization of the solar
+wind electron temperature anisotropy and the instabilities resulting from the
+interplay of the (bi-)Maxwellian core and (bi-)Kappa halo populations in the
+slow solar wind. A large set of observational data (from the Ulysses, Helios
+and Cluster missions) is used to parametrize these components and establish
+their correlations. The instabilities are significantly stimulated in the
+presence of suprathermals, and the instability thresholds shape the limits of
+the temperature anisotropy for both the core and halo populations re-stating
+the incontestable role that the selfgenerated instabilities can play in
+constraining the electron anisotropy. These results confirm a particular
+implication of the suprathermal electrons which are less dense but hotter than
+thermal electrons.",1704.05311v2
+2017-04-18,On commutativity and near commutativity of translational and rotational averages: Analytical proofs and numerical examinations,"We show that, in general, the translational average over a spatial
+variable---discussed by Backus \cite{backus}, and referred to as the
+equivalent-medium average---and the rotational average over a symmetry group at
+a point---discussed by Gazis et al. \cite{gazis}, and referred to as the
+effective-medium average---do not commute. However, they do commute in special
+cases of particular symmetry classes, which correspond to special relations
+among the elasticity parameters. We also show that this noncommutativity is a
+function of the strength of anisotropy. Surprisingly, a perturbation of the
+elasticity parameters about a point of weak anisotropy results in the
+commutator of the two types of averaging being of the order of the {\it
+square\/} of this perturbation. Thus, these averages nearly commute in the case
+of weak anisotropy, which is of interest in such disciplines as quantitative
+seismology, where the weak-anisotropy assumption results in empirically
+adequate models.",1704.05541v3
+2017-04-21,Charge/quadrupole fluctuations and gap anisotropy in BiS$_2$-based superconductors,"Recent angle-resolved spectroscopy in BiS$_2$-based superconductors has
+indicated that the superconducting gap amplitude possesses remarkable
+anisotropy and/or a sign change on a small Fermi pocket around $X$ point. It
+implies a possibility of an unconventional pairing state. Here we study the gap
+anisotropy in superconductivity mediated by inherent charge/quadrupole
+fluctuations in an extended Hubbard model, which includes inter-site
+interaction between Bi and S atoms. The first-principles downfolded band
+structure is composed of Bi $6p_x/p_y$ and S $3p_x/p_y$ orbitals on a BiS$_2$
+single layer. Evaluating the linearized gap equation, we find that the ferroic
+charge/quadrupole fluctuation driven by the inter-site interaction leads to a
+fully-gapped $d_{x^2-y^2}$-wave pairing state, in which the gap amplitude has
+sizable anisotropy on the Fermi surface.",1704.06396v1
+2017-05-08,Angular dependence of magnetization reversal in epitaxial chromium telluride thin films with perpendicular magnetic anisotropy,"We investigate magnetic anisotropy and magnetization reversal mechanism in
+chromium telluride thin films grown by molecular beam epitaxy. We report
+existence of strong perpendicular anisotropy in these thin films, along with a
+relatively strong second order anisotropy contribution. The angular variation
+of the switching field observed from the magnetoresistance measurement is
+explained quantitatively using a one-dimensional defect model. The model
+reveals the relative roles of nucleation and pinning in the magnetization
+reversal, depending on the applied field orientation. Micromagnetic simulations
+are performed to visualize the domain structure and switching process.",1705.03121v1
+2017-05-09,Large magnetic anisotropy in $Fe_xTaS_2$ single crystals,"In intercalated transition metal dichalcogenide $Fe_xTaS_2$ (0.2 $\leq$ x
+$\leq$ 0.4) single crystals, large magnetic anisotropy is observed. Transport
+property measurements indicate that heavy Fe-doping leads to a large anisotropy
+of resistivity ($\rho$$_{c}$/$\rho$$_{ab}$). A sharp M-H hysteresis curve is
+observed with magnetic field along c-axis, while a linear magnetization appears
+with magnetic field applied in the ab-plane. The angular dependent magnetic
+susceptibility from in-plane to out-of-plane indicates that magnetic moments
+are strongly pinned along the c-axis in an unconventional manner and the
+coercive field reaches as large as 6 T at T = 5 K. First-principles calculation
+clearly suggests that the strong spin-orbital coupling give rise to such a
+large anisotropy of magnetism. The strong pinning effect of magnetic moments
+along c-axis makes this material a very promising candidate for the development
+of spin-aligner in spintronics devices.",1705.03139v1
+2017-05-31,Giant Spin Lifetime Anisotropy in Graphene Induced by Proximity Effects,"We report on fundamental aspects of spin dynamics in graphene interfaced with
+transition metal dichalcogenides (TMDCs). By using realistic models derived
+from first principles we compute the spin lifetime anisotropy, defined as the
+ratio of lifetimes for spins pointing out of the graphene plane to those
+pointing in the plane. In the presence of strong intervalley scattering the
+anisotropy can reach unprecedented values of tens to hundreds, while it reduces
+to 1/2 for weak disorder. This behavior is mediated by spin-valley locking,
+which is strong in TMDCs and is imprinted onto graphene. Such giant spin
+transport anisotropy, driven by proximity effects, provides an exciting
+paradigm for designing novel spin device functionalities.",1705.10972v2
+2017-06-08,Current-Voltage Characteristics of Borophene and Borophane Sheets,"Motivated by recent experimental and theoretical research on a monolayer of
+Boron atoms, Borophene, current-voltage characteristics of three different
+Borophene sheets, 2Pmmn, 8Pmmn and 8Pmmm, are calculated using density
+functional theory combined with nonequilibriumGreen function formalism.
+Borophene sheets with two and eight atoms in a unit cell are considered and
+bandstructure, electron density and structural anisotropy of them are analyzed
+in details. Results show that 8Pmmn and 8Pmmm structures which have eight atoms
+in the unit cell have less anisotropy than 2Pmmn. In addition, although 8Pmmn
+shows a Dirac cone in the bandstructure, its current is lower than two others.
+We also consider a fully hydrogenated Borophene, Borophane, and find that the
+hydrogenation process reduces the structural anisotropy and the current
+significantly. Our findings reveal that the current-voltage characteristics of
+the Borophene sheets can be used to detect the kind and the growth direction of
+the sample because it is strongly dependent on the direction of the electron
+transport, anisotropy and details of the unit cell of the Borophene.",1706.02511v1
+2017-06-26,CMB anisotropies at all orders: the non-linear Sachs-Wolfe formula,"We obtain the non-linear generalization of the Sachs-Wolfe + integrated
+Sachs-Wolfe (ISW) formula describing the CMB temperature anisotropies. Our
+formula is valid at all orders in perturbation theory, is also valid in all
+gauges and includes scalar, vector and tensor modes. A direct consequence of
+our results is that the maps of the logarithmic temperature anisotropies are
+much cleaner than the usual CMB maps, because they automatically remove many
+secondary anisotropies. This can for instance, facilitate the search for
+primordial non-Gaussianity in future works. It also disentangles the non-linear
+ISW from other effects. Finally, we provide a method which can iteratively be
+used to obtain the lensing solution at the desired order.",1706.08428v2
+2017-06-30,Stability of the spin-$1/2$ kagome ground state with breathing anisotropy,"We numerically study the spin-$1/2$ breathing kagome lattice. In this
+variation of the kagome Heisenberg antiferromagnet, the spins belonging to
+upward and downward facing triangles have different coupling strengths. Using
+the density matrix renormalization group (DMRG) method and exact
+diagonalization, we show that the kagome antiferromagnet spin liquid is
+extremely robust to this anisotropy. Materials featuring this anisotropy -- and
+especially the recently studied vanadium compound
+$[{\mathrm{NH}}_{4}{]}_{2}[{\mathbf{C}}_{7}{\mathbf{H}}_{14}\mathbf{N}][{\mathbf{V}}_{7}{\mathbf{O}}_{6}{\mathbf{F}}_{18}]$
+(DQVOF) -- may thus be very good candidates to realize the much studied kagome
+spin liquid. Further, we closely examine the limit of strong breathing
+anisotropy and find indications of a transition to a nematic phase.",1706.10105v1
+2017-07-07,Nonlinear electric field effect on perpendicular magnetic anisotropy in Fe/MgO interfaces,"The electric field effect on magnetic anisotropy was studied in an ultrathin
+Fe(001) monocrystalline layer sandwiched between Cr buffer and MgO tunnel
+barrier layers, mainly through post-annealing temperature and measurement
+temperature dependences. A large coefficient of the electric field effect of
+more than 200 fJ/Vm was observed in the negative range of electric field, as
+well as an areal energy density of perpendicular magnetic anisotropy (PMA) of
+around 600 uJ/m2. More interestingly, nonlinear behavior, giving rise to a
+local minimum around +100 mV/nm, was observed in the electric field dependence
+of magnetic anisotropy, being independent of the post-annealing and measurement
+temperatures. The insensitivity to both the interface conditions and the
+temperature of the system suggests that the nonlinear behavior is attributed to
+an intrinsic origin such as an inherent electronic structure in the Fe/MgO
+interface. The present study can contribute to the progress in theoretical
+studies, such as ab initio calculations, on the mechanism of the electric field
+effect on PMA.",1707.02067v1
+2017-07-18,Large Magnetic Anisotropy of an Iron-Porphyrin Complex on Metal Substrate,"Single magnetic atoms or molecules with large single-ion magnetic anisotropy
+are highly desired for future applications in high-density data storage and
+quantum computation. Here we have synthesized an Fe-porphyrin complex on
+Au(111) substrate in a controlled way, and revealed large magnetic anisotropy
+energy of more than 15 meV by low-temperature scanning tunneling microscopy and
+spectroscopy. Two magnetic states with opposite spin directions are
+discriminated by inelastic electron tunneling spectroscopy in varied magnetic
+field, and are found to have long spin lifetimes. First-principle calculations
+reveal that the weak ligand filed in this complex keeps the Fe atom in a
+high-spin state and preserves its large orbital angular momentum, which gives
+rise to an easy-axis perpendicular to the molecular plane and large magnetic
+anisotropy energy by spin-orbit coupling.",1707.05434v1
+2017-07-23,A core-shell-surface layer model to explain the size dependence of effective magnetic anisotropy in magnetic nanoparticles,"The particle size (D) dependence of the effective magnetic anisotropy Keff of
+magnetic nanoparticles (NPs) usually shows Keff increasing with decreasing D.
+This dependence is often interpreted using the Eq.: Keff = Kb + (6Ks/D) where
+Kb and Ks are the anisotropy constants of the spins in the bulk-like core and
+surface layer, respectively. Here, we show that this model is inadequate to
+explain the observed size-dependency of Keff for smaller nanoparticles with D <
+5 nm. Instead the results in NPs of maghemite ({\gamma}-Fe2O3), NiO and Ni are
+best described by an extension of the above model leading to the variation
+given by Keff = Kb + (6Ks/D) +Ksh{[1-(2d/D)]^(-3) -1}, where the last term is
+due to the spins in a shell of thickness d with anisotropy Ksh. The validation
+of this core-shell-surface layer (CSSL) model for three different magnetic NPs
+systems viz. ferrimagnetic {\gamma}-Fe2O3, ferromagnetic Ni and
+antiferromagnetic NiO suggests its possible applicability for all magnetic
+nanoparticles.",1707.07241v1
+2017-07-28,An Introduction to the Planck Mission,"The Cosmic Microwave Background (CMB) is the oldest light in the universe. It
+is seen today as black body radiation at a near-uniform temperature of 2.73K
+covering the entire sky. This radiation field is not perfectly uniform, but
+includes within it temperature anisotropies of order delta(T)/T ~ 10E-5.
+Physical processes in the early universe have left their fingerprints in these
+CMB anisotropies, which later grew to become the galaxies and large scale
+structure we see today. CMB anisotropy observations are thus a key tool for
+cosmology. The Planck Mission was the European Space Agency's (ESA) probe of
+the CMB. Its unique design allowed CMB anisotropies to be measured to greater
+precision over a wider range of scales than ever before. This article provides
+an introduction to the Planck Mission, including its goals and motivation, its
+instrumentation and technology, the physics of the CMB, how the contaminating
+astrophysical foregrounds were overcome, and the key cosmological results that
+this mission has so far produced.",1707.09220v1
+2017-08-05,Third order perturbed Heisenberg Hamiltonian of sc ferromagnetic films with fifty spin layers,"Magnetic energy of simple cubic structured ferromagnetic films with 10 to 50
+spin layers was determined using third order perturbed Heisenberg Hamiltonian.
+By plotting 3-D plot of energy versus angle and stress induced anisotropy, the
+values of stress induced anisotropy corresponding to energy minimums and
+maximums were determined. By plotting the graphs of energy versus angle at
+these different stress induced anisotropy values, the easy and hard directions
+were determined. Magnetic easy and hard directions are related to energy
+minimums and maximums of the curve. Similar graphs were plotted for spin
+exchange interaction to determine the easy and hard directions. Graphs of
+energy versus angle were plotted by keeping all the magnetic energy parameters
+at constant values for each number of spin layers to determine the variation of
+magnetic easy directions, hard direction and corresponding energies with the
+number of spin layers. The magnetic easy axis gradually rotates from out of
+plane to in plane direction as the number of spin layers is increased. In
+addition, the magnetic anisotropy energy increases with the number of spin
+layers.",1708.02996v1
+2017-08-31,Antiferromagnetic anisotropy determination by spin Hall magnetoresistance,"An electric method for measuring magnetic anisotropy in antiferromagnetic
+insulators (AFIs) is proposed. When a metallic film with strong spin-orbit
+interactions, e.g., platinum (Pt), is deposited on an AFI, its resistance
+should be affected by the direction of the AFI N eel vector due to the spin
+Hall magnetoresistance (SMR). Accordingly, the direction of the AFI N eel
+vector, which is affected by both the external magnetic field and the magnetic
+anisotropy, is reflected in resistance of Pt. The magnetic field angle
+dependence of the resistance of Pt on AFI is calculated by consider- ing the
+SMR, which indicates that the antiferromagnetic anisotropy can be obtained
+experimentally by monitoring the Pt resistance in strong magnetic fields.
+Calculations are performed for realistic systems such as Pt/Cr2O3, Pt/NiO, and
+Pt/CoO.",1708.09564v1
+2017-09-05,Semianalytic calculation of cosmic microwave background anisotropies from wiggly and superconducting cosmic strings,"We study how the presence of world-sheet currents affects the evolution of
+cosmic string networks, and their impact on predictions for the cosmic
+microwave background (CMB) anisotropies generated by these networks. We provide
+a general description of string networks with currents and explicitly
+investigate in detail two physically motivated examples: wiggly and
+superconducting cosmic string networks. By using a modified version of the
+CMBact code, we show quantitatively how the relevant network parameters in both
+of these cases influence the predicted CMB signal. Our analysis suggests that
+previous studies have overestimated the amplitude of the anisotropies for
+wiggly strings. For superconducting strings the amplitude of the anisotropies
+depends on parameters which presently are not well known - but which can be
+measured in future high-resolution numerical simulations.",1709.01839v4
+2017-09-23,"Electron Mobility in Monoclinic β-Ga2O3 - Effect of Plasmon-phonon Coupling, Anisotropy, and Confinement","This work reports an investigation of electron transport in monoclinic
+\beta-Ga2O3 based on a combination of density functional perturbation theory
+based lattice dynamical computations, coupling calculation of lattice modes
+with collective plasmon oscillations and Boltzmann theory based transport
+calculations. The strong entanglement of the plasmon with the different
+longitudinal optical (LO) modes make the role LO-plasmon coupling crucial for
+transport. The electron density dependence of the electron mobility in
+\beta-Ga2O3 is studied in bulk material form and also in the form of
+two-dimensional electron gas. Under high electron density a bulk mobility of
+182 cm2/ V.s is predicted while in 2DEG form the corresponding mobility is
+about 418 cm2/V.s when remote impurities are present at the interface and
+improves further as the remote impurity center moves away from the interface.
+The trend of the electron mobility shows promise for realizing high electron
+mobility in dopant isolated electron channels. The experimentally observed
+small anisotropy in mobility is traced through a transient Monte Carlo
+simulation. It is found that the anisotropy of the IR active phonon modes is
+responsible for giving rise to the anisotropy in low-field electron mobility.",1709.08117v1
+2017-10-18,Collective modes in multicomponent condensates with anisotropy,"We report the effects of anisotropy in the confining potential on two
+component Bose-Einstein condensates (TBECs) through the properties of the low
+energy quasiparticle excitations. Starting from generalized Gross Pitaevskii
+equation, we obtain the Bogoliubov de-Gennes (BdG) equation for TBECs using the
+Hartree-Fock-Bogoliubov (HFB) theory. Based on this theory, we present the
+influence of radial anisotropy on TBECs in the immiscible or the
+phase-separated domain. In particular, the TBECs of $^{85}$Rb~-$^{87}$Rb and
+$^{133}$Cs~-$^{87}$Rb TBECs are chosen as specific examples of the two possible
+interface geometries, shell-structured and side by side, in the immiscible
+domain. We also show that the dispersion relation for the TBEC shell-structured
+interface has two branches, and anisotropy modifies the energy scale and
+structure of the two branches.",1710.06673v1
+2017-10-20,Out-of-plane Enhanced Magnetic Anisotropy Energy in Ni$_{3}$Bz$_{3}$ molecule,"Organometallic complexes formed by transition metals clusters and benzene
+molecules have already been synthesized, and in selected cases display magnetic
+properties controlled by external magnetic fields. We have studied Ni$_n$Bz$_n$
+complexes made of nickel atoms surrounded by benzene molecules and here we
+focus specifically on the magnetic molecule Ni$_{3}$Bz$_{3}$. By means of
+calculations including relativistic spin-orbit terms, we show that this
+molecule reveals a large magnetic anisotropy energy of approximately 8 meV,
+found with the easy axis perpendicular to the metal atoms plane. Note that the
+matching bare Ni$_{3}$ cluster have similar magnetic anisotropy, however the
+easy axis is in-plane. Covering with benzene molecules is thus switching the
+easy axis from in-plane for Ni$_3$ to out-of-plane for Ni$_{3}$Bz$_{3}$. The
+large out-of-plane magnetic anisotropy of Ni$_{3}$Bz$_{3}$ suggests that this
+molecule could indeed be used as part in the design of molecular magnetic
+memories.",1710.07519v2
+2017-10-31,Constraints on Patchy Reionization from Planck CMB Temperature Trispectrum,"We present constraints on the patchy reionization by measuring the
+trispectrum of the Planck 2015 cosmic microwave background (CMB) temperature
+anisotropies. The patchy reionization leads to anisotropies in the CMB optical
+depth, and the statistics of the observed CMB anisotropies is altered. We
+estimate the trispectrum of the CMB temperature anisotropies to constrain
+spatial variation of the optical depth. We show that the measured trispectrum
+is consistent with that from the standard lensed CMB simulation at $2\sigma$.
+While no evidence of the patchy reionization is found in the Planck 2015
+temperature trispectrum, the CMB constraint on the patchy reionization is
+significantly improved from previous works. Assuming the analytic bubble-halo
+model of Wang and Hu (2006), the constraint obtained in this work rules out the
+typical bubble size at the ionization fraction of $\sim0.5$ as $R\gtrsim 10$
+Mpc. Further, our constraint implies that large-scale $B$-modes from the patchy
+reionization are not a significant contamination in detecting the primordial
+gravitational waves of $r\gtrsim0.001$ if the $B$ mode induced by the patchy
+reionization is described by Dvorkin et al. (2009). The CMB trispectrum data
+starts to provide meaningful constraints on the patchy reionization.",1711.00058v2
+2017-11-17,The parametric instability of Alfvén waves: effects of temperature anisotropy,"We study the stability of large amplitude, circularly polarized Alfv\'en
+waves in an anisotropic plasma described by the double-adiabatic/CGL closure,
+and in particular the effect of a background thermal pressure anisotropy on the
+well-known properties of Alfv\'en wave parametric decay in Magnetohydrodynamics
+(MHD). Anisotropy allows instability over a much wider range of values of
+parallel plasma beta ($\beta_\parallel$) when $\xi=p_{0\bot}/p_{0\parallel} >
+1$. When the pressure anisotropy exceeds a critical value, $\xi\geq\xi^*$ with
+$\xi^*\simeq2.7$, there is a new regime in which the parametric instability is
+no longer quenched at high $\beta_\parallel$ and in the limit
+$\beta_\parallel\gg1$ the growth rate becomes independent of $\beta_\parallel$.
+In the opposite case of $\xi< \xi^*$, the instability is strongly suppressed
+with increasing parallel plasma beta, similarly to the MHD case. We analyze
+marginal stability conditions for parametric decay in the
+$(\xi,\,\beta_\parallel)$ parameter space, and discuss possible implications
+for Alfv\'enic turbulence in the solar wind.",1711.06371v1
+2017-11-27,Deriving galaxy cluster velocity anisotropy profiles from a joint analysis of dynamical and weak lensing data,"We present an analytic approach to lift the mass-anisotropy degeneracy in
+clusters of galaxies by utilizing the line-of-sight velocity dispersion of
+clustered galaxies jointly with weak lensing inferred masses. More
+specifically, we solve the spherical Jeans equation by assuming a simple
+relation between the line-of-sight velocity dispersion and the radial velocity
+dispersion and recast the Jeans equation as a Bernoulli differential equation
+that has a well-known analytic solution. We first test our method in
+cosmological N-body simulations and then derive the anisotropy profiles for 35
+archival data galaxy clusters with an average redshift of $\langle
+{z}_{c}\rangle =0.25$. The resulting profiles yield a weighted average global
+value of $\langle \beta (0.2\leqslant R/{R}_{200}\leqslant 1)\rangle =0.35\pm
+0.28$ (stat) \pm 0.15 (sys). This indicates that clustered galaxies tend to
+globally fall on radially anisotropic orbits. We note that this is the first
+attempt to derive velocity anisotropy profiles for a cluster sample of this
+size utilizing joint dynamical and weak lensing data",1711.10018v2
+2018-01-03,Effect of low anisotropy on cosmological models by using supernova data,"By using the supernovae type Ia data we study influence of the anisotropy
+(although low) on the evolution of the universe and compare ${\Lambda}$CDM
+model with 6 representative parametrizations of the recent Hubble expansion
+history $H(z)$. To compare these models we use the the maximum likelihood
+method for find that the best fit dynamical $\omega(z)$ and $q(z)$ obtained
+from the SNIa dataset. In particular we find the best fit value of $\Lambda$CDM
+model $(\Omega_{\sigma_0}= 0.013$, $\chi^2_{min}=197.56)$. The analysis shows
+that by considering the anisotropy, it leads to more best fit parameters in all
+models (except of SCDM) with SNIa data. We also use two statistical tests such
+as the usual $\chi^2_{min}/dof$ and p-test to compare different dark energy
+models. According to both statistical tests and considering anisotropy, the
+linear parametrization model that is providing the best fit to $\Lambda$CDM
+model.",1801.01094v3
+2018-02-02,Testing the anisotropy of the universe using the simulated gravitational wave events from advanced LIGO and Virgo,"The detection of gravitational waves (GWs) provides a powerful tool to
+constrain the cosmological parameters. In this paper, we investigate the
+possibility of using GWs as standard sirens in testing the anisotropy of the
+universe. We consider the GW signals produced by the coalescence of binary
+black hole systems and simulate hundreds of GW events from the advanced Laser
+Interferometer Gravitational-Wave Observatory (LIGO) and Virgo. It is found
+that the anisotropy of the universe can be tightly constrained if the redshift
+of the GW source is precisely known. The anisotropic amplitude can be
+constrained with an accuracy comparable to the Union2.1 complication of type-Ia
+supernovae if $\gtrsim 400$ GW events are observed. As for the preferred
+direction, $\gtrsim 800$ GW events are needed in order to achieve the accuracy
+of Union2.1. With 800 GW events, the probability of pseudo anisotropic signals
+with an amplitude comparable to Union2.1 is negligible. These results show that
+GWs can provide a complementary tool to supernovae in testing the anisotropy of
+the universe.",1802.00642v2
+2018-02-02,Spin-orbit coupling induced magnetic anisotropy and large spin wave gap in $\rm Na Os O_3$,"The role of spin-orbit coupling and Hund's rule coupling on magnetic
+ordering, anisotropy, and excitations are investigated within a minimal
+three-orbital model for the $5d^3$ compound $\rm Na Os O_3$. Asymmetry between
+the magnetic moments for the $xy$ and $xz,yz$ orbitals, arising from the
+hopping asymmetry generated by the $\rm Os O_6$ octahedral tilting and
+rotation, together with the weak correlation effect, are shown to be crucial
+for the large SOC induced magnetic anisotropy and spin wave gap observed in
+this compound. Due to the intrinsic SOC-induced changes in the electronic
+densities under rotation of the staggered field, their coupling with the
+orbital energy offset is also found to contribute significantly to the magnetic
+anisotropy energy.",1802.01449v2
+2018-02-22,Gravitational decoupled anisotropies in compact stars,"Simple generic extensions of isotropic Durgapal--Fuloria stars to the
+anisotropic domain are presented. These anisotropic solutions are obtained by
+guided minimal deformations over a self gravitating isotropic system. When the
+isotropic and the anisotropic sector interacts in a purely gravitational
+manner, the conditions to decouple both sectors by means of the minimal
+geometric deformation approach are satisfied. Hence the anisotropic field
+equations are isolated resulting a more treatable set. The simplicity of the
+equations allows one to manipulate the anisotropies that can be implemented in
+a systematic way to obtain different realistic models for anisotropic
+configurations. Later on, observational effects of such anisotropies when
+measuring the redshift are discussed. To conclude, the application of the
+method over anisotropic solutions is generalized. In this manner, different
+anisotropic sectors can be isolated of each other and modeled in a simple and
+systematic way. Besides, a generic property of the minimal geometric
+deformation approach, its noncommutativity, is discussed. This property
+duplicates the solutions obtained through this approach; anisotropies applied
+in the reversed order give different physically acceptable configurations.",1802.08000v1
+2018-03-26,Uniaxial anisotropy and enhanced magnetostriction of CoFe$_2$O$_4$ induced by reaction under uniaxial pressure with SPS,"In this study, we have compared magnetic and magnetostrictive properties of
+polycrystalline CoFe$_2$O$_4$ pellets, produced by three different methods,
+focusing on the use of Spark Plasma Sintering (SPS). This technique allows a
+very short heat treatment stage while a uniaxial pressure is applied. SPS was
+utilized to sinter cobalt ferrite but also to make the reaction and the
+sintering (reactive sintering) of the same ceramic composition. Magnetic and
+magnetostrictive measurements show that the reactive sintering with SPS induces
+a uniaxial anisotropy, while it is not the case with a simple sintering
+process. The induced anisotropy is then expected to be a consequence of the
+reaction under uniaxial pressure. This anisotropy enhanced the magnetostrictive
+properties of the sample, where a maximum longitudinal magnetostriction of
+$-229$~ppm is obtained. This process can be a promising alternative to the
+magnetic-annealing because of the short processing time required (22 minutes).",1803.09656v1
+2018-03-30,Gate-controlled anisotropy in Aharonov-Casher spin interference: signatures of Dresselhaus spin-orbit inversion and spin phases,"The coexistence of Rashba and Dresselhaus spin-orbit interactions (SOIs) in
+semiconductor quantum wells leads to an anisotropic effective field coupled to
+carriers' spins. We demonstrate a gate-controlled anisotropy in Aharonov-Casher
+(AC) spin interferometry experiments with InGaAs mesoscopic rings by using an
+in-plane magnetic field as a probe. Supported by a perturbation-theory
+approach, we find that the Rashba SOI strength controls the AC resistance
+anisotropy via spin dynamic and geometric phases and establish ways to
+manipulate them by employing electric and magnetic tunings. Moreover, assisted
+by two-dimensional numerical simulations, we identify a remarkable anisotropy
+inversion in our experiments attributed to a sign change in the renormalized
+linear Dresselhaus SOI controlled by electrical means, which would open a door
+to new possibilities for spin manipulation.",1803.11371v2
+2018-03-31,Vibration-induced modulation of magnetic anisotropy in a magnetic molecule,"We theoretically analyze the spectrum of a magnetic molecule when its charge
+and spin can couple to the molecular vibrations. More specifically, we show
+that the interplay between charge-vibron and spin-vibron coupling leads to a
+renormalization of the magnetic anisotropy parameters of the molecule. This
+effect is discussed for a model device consisting of an individual magnetic
+molecule embedded in a junction. We study the transport properties of the
+device and illustrate how the differential conductance is affected by the
+vibrationally induced renormalization of the magnetic anisotropy. Depending on
+the total molecular spin and the bare (intrinsic) magnetic anisotropy, the
+induced modulation can lead to visible shifts and crossings in the spectrum,
+and it can even be the cause of a transport blockade. It is therefore of
+particular interest to use mechanically controllable break junctions, since in
+such a case, the relevant coupling between the molecular spin and vibrations
+can be controlled via deformations of the molecule when stretching or
+compressing the junction.",1804.00142v2
+2018-04-18,Ferromagnetic resonance linewidth in coupled layers with easy-plane and perpendicular magnetic anisotropies,"Magnetic bilayers with different magnetic anisotropy directions are
+interesting for spintronic appli- cations as they offer the possibility to
+engineer tilted remnant magnetization states. We investigate the ferromagnetic
+resonance (FMR) linewidth of modes associated with two interlayer exchange-
+coupled ferromagnetic layers, the first a CoNi multilayer with a perpendicular
+magnetic anisotropy, and the second a CoFeB layer with an easy-plane
+anisotropy. For antiferromagnetic interlayer ex- change coupling, elevated FMR
+linewidths are observed below a characteristic field. This is in contrast to
+what is found in uncoupled, ferromagnetically coupled and single ferromagnetic
+layers in which the FMR linewidth increases monotonically with field. We show
+that the characteristic field at which there is a dramatic increase in FMR
+linewidth can be understood using a macrospin model with Heisenberg-type
+exchange coupling between the layers.",1804.06796v1
+2018-04-25,Spin precession in anisotropic media,"We generalize the diffusive model for spin injection and detection in
+nonlocal spin structures to account for spin precession under an applied
+magnetic field in an anisotropic medium, for which the spin lifetime is not
+unique and depends on the spin orientation.We demonstrate that the spin
+precession (Hanle) line shape is strongly dependent on the degree of anisotropy
+and on the orientation of the magnetic field. In particular, we show that the
+anisotropy of the spin lifetime can be extracted from the measured spin signal,
+after dephasing in an oblique magnetic field, by using an analytical formula
+with a single fitting parameter. Alternatively, after identifying the
+fingerprints associated with the anisotropy, we propose a simple scaling of the
+Hanle line shapes at specific magnetic field orientations that results in a
+universal curve only in the isotropic case. The deviation from the universal
+curve can be used as a complementary means of quantifying the anisotropy by
+direct comparison with the solution of our generalized model. Finally, we
+applied our model to graphene devices and find that the spin relaxation for
+graphene on silicon oxide is isotropic within our experimental resolution.",1804.09426v1
+2018-05-04,GETMe.anis: On geometric polygon transformations leading to anisotropy,"This work contributes to the analysis of linear geometric polygon
+transformations with the aim to force a desired shape by an iterative
+procedure.",1805.01767v1
+2018-05-10,Zener Pinning through Coherent Precipitates: A Phase Field Study,"A novel phase field model has been developed to study the effect of coherent
+precipitate on the Zener pinning of matrix grain boundaries. The model accounts
+for misfit strain between precipitate and matrix as well as the elastic
+inhomogeneity and anisotropy between them. The results show that increase in
+elastic misfit, elastic inhomogeneity, and elastic anisotropy increases the
+coarsening rate of the precipitates. Increased coarsening of precipitates in
+turn decreases the pinning of grain boundaries. Therefore, increase in misfit
+strain, elastic inhomogeneity and anisotropy negatively affect the Zener
+pinning through coherent precipitate. This study shows elastic anisotropy gives
+rise to the needle shape precipitate. It has also been shown that these needle
+shaped precipitates are not very effective in Zener pinning. This study
+provides an understanding into the effect of coherent precipitate on the Zener
+pinning of matrix grain boundaries.",1805.03831v2
+2018-05-31,Observation of spin-valley coupling induced large spin lifetime anisotropy in bilayer graphene,"We report the first observation of a large spin lifetime anisotropy in
+bilayer graphene (BLG) fully encapsulated between hexagonal boron nitride. We
+characterize the out-of-plane ($\tau_\perp$) and in-plane ($\tau_\parallel$)
+spin lifetimes by oblique Hanle spin precession. At 75~K and the charge
+neutrality point (CNP) we observe a strong anisotropy of
+$\tau_\perp/\tau_\parallel$ = 8 $\pm$ 2. This value is comparable to
+graphene/TMD heterostructures, whereas our high quality BLG provides with
+$\tau_\perp$ up to 9~ns, a more than two orders of magnitude larger spin
+lifetime. The anisotropy decreases to 3.5 $\pm$ 1 at a carrier density of n =
+$6\times 10^{11}~$cm$^{-2}$. Temperature dependent measurements show above 75~K
+a decrease of $\tau_\perp/\tau_\parallel$ with increasing temperature, reaching
+the isotropic case close to room temperature. We explain our findings with
+electric field induced spin-valley coupling arising from the small intrinsic
+spin orbit fields in BLG of 12~$\mu$eV at the CNP.",1805.12420v1
+2018-06-05,Anisotropies in the astrophysical gravitational-wave background: Predictions for the detection of compact binaries by LIGO and Virgo,"We develop a detailed anisotropic model for the astrophysical
+gravitational-wave background, including binary mergers of two stellar-mass
+black holes, two neutron stars, or one of each, which are expected to be the
+strongest contributions in the LIGO-Virgo frequency band. The angular spectrum
+of the anisotropies, quantified by the $C_\ell$ components, is calculated using
+two complementary approaches: (i) a simple, closed-form analytical expression,
+and (ii) a detailed numerical study using an all-sky mock light cone galaxy
+catalogue from the Millennium simulation. The two approaches are in excellent
+agreement at large angular scales, and differ by a factor of order unity at
+smaller scales. These anisotropies are considerably larger in amplitude than
+e.g. those in the temperature of the cosmic microwave background, confirming
+that it is important to model these anisotropies, and indicating that this is a
+promising avenue for future theoretical and observational work.",1806.01718v2
+2018-06-08,The measurements of matter density perturbations amplitude from cosmological data,"We compare various physically different measurements of linear matter density
+perturbation amplitude, $sigma_8$, which are obtained from the observations of
+CMB anisotropy, galaxy cluster mass function, weak gravitation lensing, matter
+power spectrum and redshift space distortions. We show that $\sigma_8$
+measurement from CMB gravitational lensing signal based on Planck CMB
+temperature anisotropy data at high multipoles, $\ell>1000$, contradict to all
+other measurements obtained both from remaining Planck CMB anisotropy data and
+from other cosmological data, at about $3.7\sigma$ significance level.
+Therefore, these data currently should not be combined with other data to
+constrain cosmological parameters.
+  With the exception of Planck CMB temperature anisotropy data at high
+multipoles, all other measurements are in good agreement between each other and
+give the following measurements of linear density perturbation amplitude:
+$\sigma_8=0.792\pm0.006$, mean density of the Universe:
+$\Omega_m=0.287\pm0.007$, and Hubble constant: $H_0 = 69.4\pm
+0.6$~km~s$^{-1}$~Mpc$^{-1}$. Taking in account the data on baryon acoustic
+oscillations and (or) direct measurements of the Hubble constant, one can
+obtain different constraints on sum of neutrino mass and number of relativistic
+species.",1806.03261v3
+2018-07-05,Domain wall dynamics for an in-plane magnetized thin film with large perpendicular hard axis anisotropy including Dzyaloshinskii-Moriya interaction,"We consider a thin ferromagnetic layer to which an external field or a
+current are applied along an in plane easy axis. The perpendicular hard axis
+anisotropy constant is large so that the out of plane magnetization component
+is smaller than the in plane components. A perturbation approach is used to
+obtain the profile and velocity of the moving domain wall. The dynamics of the
+in plane components of the magnetization is governed by a reaction diffusion
+equation which determines the speed of the profile. We find a simple analytic
+expression for the out of plane magnetization showing a symmetric distortion
+due to the motion in addition to the asymmetric component due to the
+Dzyaloshinskii--Moriya interaction. The results obtained complement previous
+studies in which either the Dzyalozhinskii vector or the out of plane hard axis
+anisotropy were assumed small. In the regime studied the Walker breakdown is
+not observed but the reaction diffusion dynamics predicts a slowing down of the
+domain wall for sufficiently large magnetic field. The transition point depends
+on the applied field, saturation magnetization and easy axis anisotropy.",1807.02032v1
+2018-07-30,Surface anisotropy in a magnetic cylinder induced by the displacement of a vortex core,"In this article we investigate the induction of a surface anisotropy due to
+the displacement of the vortex core in a cylindrical nanostructure. In fact,
+the effect of the displacement of the vortex core in the dipolar energy can be
+modeled simply as a surface anisotropy of the form $E_s = K_s
+\int_{\mathcal{S}_m} d\mathcal{S} \, (\hat{n} \cdot \hat{m})^2/2$. Moreover,
+the surface anisotropy constant $K_s$ is proportional to the cylinder in-plane
+demagnetizing factor in the direction of the core deviation, $N_y(L/R)$, i.e.,
+$K_s = \mu_0 M_0^2 R \, N_y(L/R)$, where $R$ and $L$ are the radius and the
+thickness of the cylinder, respectively. Our results show that the term of the
+nontrivial dipolar energy caused by the charges in the cylinder mantle can be
+replaced by a simple integral $E_s$ that increases the efficiency of the
+numerical calculations in the analytical study of the displacement of the
+vortex core in magnetic vortices.",1807.11349v1
+2018-08-02,Longitudinal and transverse magnetoresistance in films with tilted out-of-plane magnetic anisotropy,"Tilted off-plane magnetic anisotropy induces two unusual characteristic
+magnetotransport phenomena: extraordinary Hall effect in the presence of an
+in-plane magnetic field, and non-monotonic anisotropic magnetoresistance in the
+presence of a field normal to the sample plane. We show experimentally that
+these effects are generic, appearing in multiple ferromagnetic systems with
+tilted anisotropy introduced either by oblique deposition from a single source
+or in binary systems co-deposited from separate sources. We present a
+theoretical model demonstrating that these observations are natural results of
+the standard extraordinary Hall effect and anisotropic magnetoresistance, when
+the titled anisotropy is properly accounted for. Such a scenario may help
+explaining various previous intriguing measurements by other groups.",1808.00846v2
+2018-08-09,Helical edge transport in the presence of a magnetic impurity: the role of local anisotropy,"Helical edge modes of 2D topological insulators are supposed to be protected
+from time-reversal invariant elastic backscattering. Yet substantial deviations
+from the perfect conductance are typically observed experimentally down to very
+low temperatures. To resolve this conundrum we consider the effect of a single
+magnetic impurity with arbitrary spin on the helical edge transport. We
+consider the most general structure of the exchange interaction between the
+impurity and the edge electrons. Moreover, for the first time, we take into the
+account the local anisotropy for the impurity and show that it strongly affects
+the backscattering current in a wide range of voltages and temperatures. We
+show that the sensitivity of the backscattering current to the presence of the
+local anisotropy is different for half-integer and integer values of the
+impurity spin. In the latter case the anisotropy can significantly increase the
+backscattering correction to the current.",1808.03084v2
+2018-08-30,CMB anisotropy power spectrum of 3-sphere universe for low $l$,"We calculate the CMB anisotropy power spectrum of a closed universe for large
+angle (i.e., low $l$) due to a scale invariant fluctuation of primordial
+universe by considering the spherical harmonics for 3-sphere. In particular,
+contrary to the wide belief, we show that this consideration affects the CMB
+anisotropy power spectrum; instead of constant $l(l+1)C_l$, our consideration
+results in the supression for $l=2$, currently explained by the cosmic
+variance. As a more concrete proof of our analysis, from the low $l$ CMB
+anisotropy data \emph{alone}, we obtained
+$\Omega_{\mathrm{tot}}=1.0018^{+0.0031}_{-0.0007}$, which agrees with
+$\Omega_{\mathrm{tot}}=1.0023^{+ 0.0056}_{- 0.0054}$ from the previous anlaysis
+of WMAP+BAO+$H_0$. Thus, we conclude that our Universe is closed.",1808.10757v4
+2018-09-11,Scaling behavior in interacting systems: joint effect of anisotropy and compressibility,"Motivated by the ubiquity of turbulent flows in realistic conditions, effects
+of turbulent advection on two models of classical non-linear systems are
+investigated. In particular, we analyze model A (according to the
+Hohenberg-Halperin classification [1]) of a non-conserved order parameter and a
+model of the direct bond percolation process. Having two paradigmatic
+representatives of distinct stochastic dynamics, our aim is to elucidate to
+what extent velocity fluctuations affect their scaling behavior. The main
+emphasis is put on an interplay between anisotropy and compressibility of the
+velocity flow on their respective scaling regimes. Velocity fluctuations are
+generated by means of the Kraichnan rapid-change model, in which the anisotropy
+is due to a distinguished spatial direction n and a correlator of the velocity
+field obeys the Gaussian distribution law with prescribed statistical
+properties. As the main theoretical tool, the field-theoretic perturbative
+renormalization group is adopted. Actual calculations are performed in the
+leading (one-loop) approximation. Having obtained infra-red stable asymptotic
+regimes, we have found four possible candidates for macroscopically observable
+behavior for each model. In contrast to the isotropic case, anisotropy brings
+about enhancement of non-linearities and non-trivial regimes are proved to be
+more stable.",1809.03781v1
+2018-09-13,Magnetic anisotropy of ferromagnetic metals in low-symmetry systems,"We have constructed an analytic formula to treat the perpendicular magnetic
+anisotropy energy in ferromagnetic metals with low symmetry, such as C4V and
+C3V. We find that the anisotropy energy is proportional to a part of the
+expectation values of the orbital angular momentum and magnetic dipole
+operator. Although the result is similar to the model proposed by Laan [J.
+Phys.: Condens. Matter 10, 3239 (1998)], we have derived a concrete expression
+for the spin-flip virtual excitation process term, which can be dominant in
+atoms with small magnetic moments and/or small exchange splitting. Pt monatomic
+layer with proximity-induced spin polarization grown on Fe is an example of
+this. Other multilayer systems such as Co/Pd and Co/Ni and bilayer systems such
+as Fe(CoB)/MgO can be discussed similarly. Moreover, the relation between
+perpendicular magnetic anisotropy energy and measurable physical parameters is
+discussed based on X-ray magnetic circular dichroism spectroscopy.",1809.04749v4
+2018-09-27,On conditions for long-wave equivalent medium to be isotropic and on analysis of parameters indicating anisotropy of equivalent TI medium,"In this paper, we consider a long-wave equivalent medium to a finely
+parallel-layered inhomogeneous medium, obtained using the Backus average.
+Following the work of Postma and Backus, we show explicitly the derivations of
+the conditions to obtain the equivalent isotropic medium. We demonstrate that
+there cannot exist a transversely isotropic (TI) equivalent medium with the
+coefficients $c^{\overline{\rm TI}}_{1212} \neq c^{\overline{\rm TI}}_{2323}$,
+$c^{\overline{\rm TI}}_{1111} = c^{\overline{\rm TI}}_{3333}$ and
+$c^{\overline{\rm TI}}_{1122} = c^{\overline{\rm TI}}_{1133}$. Moreover, we
+consider a new parameter, $\varphi$, indicating the anisotropy of the
+equivalent medium, and we show its range and properties. Subsequently, we
+compare $\varphi$ to the Thomsen parameters, emphasizing its usefulness as a
+supportive parameter showing the anisotropy of the equivalent medium or as an
+alternative parameter to $\delta$. We argue with certain Berryman et al.
+considerations regarding the properties of the anisotropy parameters $\epsilon$
+and $\delta$. Additionally, we show an alternative way---to the one mentioned
+by Berryman et al.---of indicating changing fluid content in layered Earth.",1809.10385v1
+2018-09-27,Crystalline anisotropy induces a second antiferromagnetic phase in the absence of SDW in the heavily hydrogen-doped LaFeAsO$_{1-x}$H$_x$ $(x\sim0.5 )$,"Electronic and magnetic properties of the heavily H-doped
+LaFeAsO$_{1-x}$H$_x$ $(x\sim0.5 )$ were studied in the framework of the density
+functional theory combined with the dynamical mean field theory (DFT+DMFT). We
+found a stripe-like-ordered structure of hydrogen and oxygen atoms, as a ground
+state, with the same configuration as the antiferromagnetic (AF) order. The new
+configuration could explain the existing experimental results related to the
+heavily H-doped LaFeAsO$_{1-x}$H$_x$, such as an in-plane electronic anisotropy
+and a non-uniform magnetic behavior. A significant anisotropy was observed
+between Fe- 3d$_{xz}$ (xz) and Fe-3d$_{yz}$ (yz) orbitals in the ground state
+in the absence of the pseudogap resulting from the spin density wave phase,
+which was found to originate from the crystalline anisotropy. Magnetic moments
+were not spatially uniform and were sensitive to the crystal configuration. We
+found that a non-uniform magnetic behavior is associated with the As-Fe-As bond
+angle in the structure. Our findings would clarify the importance of crystal
+details and orbital degrees of freedom in iron-based superconductors.",1809.10641v1
+2018-10-12,Controlling solid-liquid interfacial energy anisotropy through the isotropic liquid,"Although the anisotropy of the solid-liquid interfacial free energy for most
+alloy systems is very small, it plays a crucial role in the growth rate,
+morphology and crystallographic growth direction of dendrites. Previous work
+posited a dendrite orientation transition via compositional additions. In this
+work we examine experimentally the change in dendrite growth behaviour in the
+Al-Sm (Samarium) system as a function of solute concentration and study its
+interfacial properties using molecular dynamics simulations. We observe a
+dendrite growth direction which changes from <100> to <110> as Sm content
+increases. The observed change in dendrite orientation is consistent with the
+simulation results for the variation of the interfacial free energy anisotropy
+and thus provides definitive confirmation of conjecture in previous works. In
+addition, our results provide physical insight into the atomic structural
+origin of the concentration dependent anisotropy, and deepens our fundamental
+understanding of solid-liquid interfaces in binary alloys.",1810.05298v2
+2018-10-15,TeV-PeV Cosmic-Ray Anisotropy and Local Interstellar Turbulence,"We calculate the shape of the large-scale anisotropy of TeV-PeV cosmic-rays
+(CR) in different models of the interstellar turbulence. In general, the
+large-scale CR anisotropy (CRA) is not a dipole, and its shape can be used as a
+new probe of the turbulence. The 400 TeV and 2 PeV data sets of IceTop can be
+fitted with Goldreich-Sridhar turbulence and a broad resonance function, but
+other possibilities are not excluded. We then present our first numerical
+calculations of the CRA down to 3 TeV energies in 3D isotropic Kolmogorov
+turbulence. At these low energies, the large-scale CRA aligns well with the
+direction of local magnetic field lines around the observer. In this type of
+turbulence, the CR intensity is flat in a broad region perpendicular to field
+lines. Even though the CRA is quite gyrotropic, we show that the local
+configuration of the turbulence around the observer does result in the
+appearance of weak, ""non-gyrotropic"" small-scale anisotropies, which contain
+information on the local turbulence level.",1810.06396v1
+2018-10-16,Drude weight anisotropy in the doped iron pnictides: the primary role of orbital weight redistribution along the reconstructed Fermi surfaces,"We explore the anisotropy in low frequency conductivity as a function of hole
+doping in multiorbital models of pnictides by analyzing the Drude weight in the
+$x$ and $y$ directions of a ($\pi$, 0) spin-density wave state. A reduction in
+the conductivity anisotropy with increased hole doping, and subsequent sign
+reversal, both observed in experiments, is found to be a common trend in these
+models. This behavior arises due to the interplay of low energy
+orbitally-resolved density of states and the geometrical features of the Fermi
+surface. An understanding of anisotropy in the electron doped regime, however,
+would require additional ingredients.",1810.06842v2
+2018-10-26,Reliable mass calculation in spherical gravitating systems,"We present an innovative approach to the methodology of dynamical modelling,
+allowing practical reconstruction of the underlying dark matter mass without
+assuming both the density and anisotropy functions. With this, the
+mass-anisotropy degeneracy is reduced to simple model inference, incorporating
+the uncertainties inherent with observational data, statistically circumventing
+the mass-anisotropy degeneracy in spherical collisionless systems. We also
+tackle the inadequacy that the Jeans method of moments has on small datasets,
+with the aid of Generative Adversarial Networks: we leverage the power of
+artificial intelligence to reconstruct non-parametrically the projected
+line-of-sight velocity distribution. We show with realistic numerical
+simulations of dwarf spheroidal galaxies that we can distinguish between
+competing dark matter distributions and recover the anisotropy and mass profile
+of the system.",1810.11375v1
+2018-10-05,Zero-field dynamics stabilized by in-plane shape anisotropy in MgO-based spin-torque oscillators,"Here we demonstrate numerically that shape anisotropy in MgO-based
+spin-torque nano-oscillators consisting of an out-of-plane magnetized free
+layer and an in-plane polarizer is necessary to stabilize out-of-plane
+magnetization precession without the need of external magnetic fields. As the
+in-plane anisotropy is increased, a gradual tilting of the magnetization
+towards the in-plane easy direction is introduced, favouring zero-field
+dynamics over static in-plane states. Above a critical value, zero-field
+dynamics are no longer observed. The optimum ratio of in-plane shape to
+out-of-plane uniaxial anisotropy, for which large angle out-of-plane zero-field
+dynamics occur within the widest current range, is reported.",1811.00106v1
+2018-11-08,Thermodynamics at Strong Coupling on Anisotropic Lattices,"Lattice QCD with staggered fermions at strong coupling has long been studied
+in a dual representation to circumvent the finite baryon density sign problem.
+Monte Carlo simulations at finite temperature and density require anisotropic
+lattices. Recent results that established the non-perturbative functional
+dependence between the bare anisotropy $\gamma$ and the physical anisotropy
+$a_s/a_t$ in the chiral limit are now extended to finite quark mass. We
+illustrate how the calibration of the anisotropy works and discuss the
+consequences of the anisotropy on thermodynamic observables. We also show first
+results on the energy density and pressure in the QCD phase diagram in the
+strong coupling regime.",1811.03584v1
+2018-11-12,Current direction anisotropy of the spin Hall magnetoresistance in nickel ferrite thin films with bulk-like magnetic properties,"We utilize spin Hall magnetoresistance (SMR) measurements to experimentally
+investigate the pure spin current transport and magnetic properties of nickel
+ferrite (NiFe2O4,NFO)/normal metal (NM) thin film heterostructures. We use
+(001)-oriented NFO thin films grown on lattice-matched magnesium gallate
+substrates by pulsed laser deposition, which significantly improves the
+magnetic and structural properties of the ferrimagnetic insulator. The NM in
+our experiments is either Pt or Ta. A comparison of the obtained SMR magnitude
+for charge currents applied in the [100]- and [110]-direction of NFO yields a
+change of 50% for Pt at room temperature. We also investigated the temperature
+dependence of this current direction anisotropy and find that it is
+qualitatively different for the conductivity and the SMR magnitude. From our
+results we conclude that the observed current direction anisotropy may
+originate from an anisotropy of the spin mixing conductance or of the spin Hall
+effect in these Pt and Ta layers, and/or additional spin-galvanic contributions
+from the NFO/NM interface.",1811.04696v1
+2018-11-17,Unconventional anisotropic even-denominator fractional quantum Hall state in a system with mass anisotropy,"The fractional quantum Hall state (FQHS) observed at a half-filled Landau
+level in an interacting two-dimensional electron system (2DES) is among the
+most exotic states of matter as its quasiparticles are expected to be Majoranas
+with non-Abelian statistics. We demonstrate here the unexpected presence of
+such a state in a novel 2DES with a strong band-mass anisotropy. The FQHS we
+observe has unusual characteristics. While its Hall resistance is
+well-quantized at low temperatures, it exhibits highly-anisotropic in-plane
+transport resembling compressible stripe/nematic charge-density-wave phases.
+More striking, the anisotropy sets in suddenly below a critical temperature,
+suggesting a finite-temperature phase transition. Our observations highlight
+how anisotropy modifies the many-body phases of a 2DES, and should further fuel
+the discussion surrounding the enigmatic even-denominator FQHS.",1811.07094v1
+2018-11-22,On the Emission Pattern of Nanoscopic Emitters in Planar Anisotropic Matrix and Nanoantenna Structures,"Single nanoscopic emitters embedded in crystalline matrix have become a
+valuable resource for emerging nanophotonic and quantum technologies. The
+generally anisotropic nature of the matrix strongly affects the emission
+properties of the quantum emitters, in particular, when the matrix is assembled
+in nanophotonic structures. We report on rigorous analysis and engineering of
+spontaneous emission from single emitters coupled to nanoantenna and planar
+anisotropic antenna structures. By developing a convenient theoretical method
+with efficient numerical implementation, we show that accurate modeling of the
+anisotropy is essential in predicting the emission pattern for many important
+systems, such as single molecules in solid-state matrix, isolated defects in 2D
+materials and so on. In particular, we illustrate the amplified effects of
+material anisotropy and geometrical anisotropy for emitters coupled to planar
+antenna and nanoantenna structures. We show that with proper design of the
+anisotropies strong enhancement of the emission rate and nearly collimated beam
+from single emitters can be simultaneously achieved.",1811.09052v1
+2019-01-01,Micro-mechanics of fabric and failure in granular materials,"The paper addresses the underlying source of two forms of induced anisotropy
+in granular materials: contact orientation anisotropy and contact force
+anisotropy. A rational, mathematical structure is reviewed for the manner in
+which fabric anisotropy emerges and evolves during loading. Fabric is expressed
+as an orientation density, and transport phenomena such as convection, contact
+generation, and diffusion control the rate of fabric evolution during loading.
+The paper proposes specific measurable forms for all terms, based upon the
+micro-mechanics of particle interactions. Discrete element (DEM) simulations
+are used to verify and quantify these terms, so that the theory can be applied
+to general loading conditions. The DEM simulations are of densely packed
+durable spheres, and the emphasis is on soil behavior at large strains,
+specifically on fabric and strength at the critical state. Once the theory has
+been developed and quantified, it is applied to predict the effect of the
+intermediate principal stress on strength.",1901.07341v1
+2019-01-25,Current-Induced Torques with Dresselhaus Symmetry Due to Resistance Anisotropy in 2D Materials,"We report measurements of current-induced torques in heterostructures of
+Permalloy (Py) with TaTe$_2$, a transition-metal dichalcogenide (TMD) material
+possessing low crystal symmetry, and observe a torque component with
+Dresselhaus symmetry. We suggest that the dominant mechanism for this
+Dresselhaus component is not a spin-orbit torque, but rather the Oersted field
+arising from a component of current that flows perpendicular to the applied
+voltage due to resistance anisotropy within the TaTe$_2$. This type of
+transverse current is not present in wires made from a single uniform layer of
+a material with resistance anisotropy, but will result whenever a material with
+resistance anisotropy is integrated into a heterostructure with materials
+having different resistivities, thereby producing a spatially non-uniform
+pattern of current flow. This effect will therefore influence measurements in a
+wide variety of heterostructures incorporating 2D TMD materials and other
+materials with low crystal symmetries.",1901.08908v1
+2019-02-07,Unidirectional anisotropy in cubic FeGe with antisymmetric spin-spin-coupling,"We report strong unidirectional anisotropy in bulk polycrystalline B20 FeGe
+measured by ferromagnetic resonance spectroscopy. Bulk and micron-sized samples
+were produced and analytically characterized. FeGe is a B20 compound with
+inherent Dzyaloshinskii-Moriya interaction. Lorenz microscopy confirms a
+skyrmion lattice at $190 \; \text{K}$ in a magnetic field of 150 mT.
+Ferromagnetic resonance was measured at $276 \; \text{K} \pm 1 \; \text{K}$,
+near the Curie temperature. Two resonance modes were observed, both exhibit a
+unidirectional anisotropy of $K=1153 \; \text{J/m}^3 \pm 10 \; \text{J/m}^3$ in
+the primary, and $K=28 \; \text{J/m}^3 \pm 2 \; \text{J/m}^3$ in the secondary
+mode, previously unknown in bulk ferromagnets. Additionally, about 25 standing
+spin wave modes are observed inside a micron-sized FeGe wedge, measured at room
+temperature ($\sim \; 293$ K). These modes also exhibit unidirectional
+anisotropy.",1902.02665v2
+2019-02-12,Numerical Anisotropy in Finite Differencing,"Numerical solutions to hyperbolic partial differential equations, involving
+wave propagations in one direction, are subject to several specific errors,
+such as numerical dispersion, dissipation or aliasing. In multi-dimensions,
+where the waves propagate in all directions, there is an additional specific
+error resulting from the discretization of spatial derivatives along grid
+lines. Specifically, waves or wave packets in multi-dimensions propagate at
+different phase or group velocities, respectively, along different directions.
+A commonly used term for the aforementioned multidimensional discretization
+error is the numerical anisotropy or isotropy error. In this review, the
+numerical anisotropy is briefly described in the context of the wave equation
+in multi-dimensions. Then, several important studies that were focused on
+optimizations of finite difference schemes with the objective of reducing the
+numerical anisotropy are discussed.",1902.04466v1
+2019-02-21,Mean flow anisotropy without waves in rotating turbulence,"We tackle the question of how anisotropy in flows subject to background
+rotation favours structures elongated along the rotation axis, especially in
+turbulent flows. A new, wave-free mechanism is identified that challenges the
+current understanding of the process. Inertial waves propagating near the
+rotation axis are generally accepted as the most efficient mechanism to
+transport energy anisotropically. They have been shown to transfer energy to
+large anisotropic, columnar structures. Nevertheless, they cannot account for
+the formation of simpler steady anisotropic phenomena such as Taylor columns.
+Here, we experimentally show that more than one mechanism involving the
+Coriolis force may promote anisotropy. In particular, in the limit of fast
+rotation, that is at low Rossby number, anisotropy favouring the direction of
+rotation of the average of a turbulent flow arises neither because of inertial
+waves nor following the same mechanism as in steady Taylor columns, but from an
+interplay between the Coriolis force and average advection.",1902.07984v2
+2019-03-02,Evolution of Internal Granular Structure at the Flow-Arrest Transition,"The evolution of the internal granular structure in shear-arrested and
+shear-flowing states of granular materials is characterized using fabric
+tensors as descriptors of the internal contact and force networks. When a
+dilute system of frictional grains is subjected to a constant pressure and
+shear stress, the bulk stress ratio is well-predicted from the anisotropy of
+its contact and force networks during transient flow prior to steady shear flow
+or shear arrest. Although the onset of shear arrest is a stochastic process,
+the fabric tensors upon arrest are distributed around nearly equal
+contributions of force and contact network anisotropy to the bulk stress ratio.
+The distribution becomes seemingly narrower with increasing system size. The
+anisotropy of the contact network in shear-arrested states is reminiscent of
+the fabric anisotropy observed in shear-jammed packings.",1903.00599v2
+2019-03-11,Effect of Anisotropy on Defect Mode Peculiariries in Chiral Liquid Crystals,"The effect of anisotropy on defect mode peculiarities in cholesteric liquid
+crystals is investigated. The problem is solved by Ambartsumians layer addition
+modified method. Two cases are considered. In the first case, it is assumed
+that the defect layer is not absorbing and the effect of refraction anisotropy
+on the reflection, relative photonic density of states and the total field
+intensity aroused in the defect layer are studied . In the second case, defect
+layer is assumed to be isotropic for refraction and anisotropic for absorption,
+and the influence of defect layer absorption anisotropy on reflection,
+absorption, relative photonic density of states and the total field intensity
+aroused in the defect layer are investigated.",1903.04924v1
+2019-04-06,The prospects of gravitational waves on constraining the anisotropy of the Universe,"The observation of GW150914 indicated a new independent measurement of the
+luminosity distance of a gravitational wave event. In this paper, we constrain
+the anisotropy of the Universe by using gravitational wave events. We simulate
+hundreds of events of binary neutron star merging that may be observed by
+Einstein Telescope. Full simulation for producing process of gravitational wave
+data is employed. We find that 200 of binary neutron star merging in redshift
+$(0,1)$ observed by Einstein Telescope may constrain the anisotropy with an
+accuracy comparable to the result from Union2.1 supernovae. This result shows
+that gravitational waves can be a powerful tool in investigating the
+cosmological anisotropy.",1904.03460v1
+2019-04-09,\txtit{In situ} determination of the anisotropy field in ferromagnetic films using magnetic susceptibility measurements by MOKE,"An alternate method of measuring anisotropy fields in thin film ferromagnets
+is demonstrated. The method relies on the magnetic susceptibility in a small
+a.c. magnetic field, measured \txtit{in situ} using the magneto-optic Kerr
+effect (MOKE), and will be useful in situations where more specialized
+apparatus are not available, or constraints discourage the use of a large,
+static magnetic field. The method is demonstrated for Co/W(110) films, where it
+yields anisotropy fields in agreement with previous studies using more
+conventional torque magnetometry. The sensitivity of the method is demonstrated
+using CoO/Co/W(110) bilayer films, where the anisotropy due to interfacial
+exchange coupling is detected and used to find the N\'{e}el temperature of the
+thin CoO layer.",1904.04855v1
+2019-04-25,Low damping magnetic properties and perpendicular magnetic anisotropy with strong volume contribution in the Heusler alloy Fe1.5CoGe,"We present a study of the dynamic magnetic properties of TiN-buffered
+epitaxial thin films of the Heusler alloy Fe$_{1.5}$CoGe. Thickness series
+annealed at different temperatures are prepared and the magnetic damping is
+measured, a lowest value of $\alpha=2.18\times 10^{-3}$ is obtained. The
+perpendicular magnetic anisotropy properties in Fe$_{1.5}$CoGe/MgO are also
+characterized. The evolution of the interfacial perpendicular anisotropy
+constant $K^{\perp}_{\rm S}$ with the annealing temperature is shown and
+compared with the widely used CoFeB/MgO interface. A large volume contribution
+to the perpendicular anisotropy of $(4.3\pm0.5)\times 10^{5}$ $\rm J/m^3$ is
+also found, in contrast with vanishing bulk contribution in common Co- and
+Fe-based Heusler alloys.",1904.11247v1
+2019-05-01,A partial inventory of observational anisotropies in single-dish line-intensity mapping,"Line-intensity mapping, being an imperfect observation of the line-intensity
+field in a cosmological volume, will be subject to various anisotropies
+introduced in observation. Existing literature in the context of CO and [C II]
+line-intensity mapping often predicts only the real-space, spherically averaged
+line-intensity power spectrum, with some works considering anisotropies while
+examining projection of interloper emission. We explicitly consider a
+simplified picture of redshift-space distortions and instrumental effects due
+to limited resolution, and how these distort an isotropic line-intensity signal
+in real space and introduce strong apparent anisotropies. The results suggest
+that while signal loss due to limited instrumental resolution is unavoidable,
+measuring the quadrupole power spectrum in addition to the monopole would still
+break parameter degeneracies present in monopole-only constraints, even without
+a measurement of the full anisotropic power spectrum.",1905.00209v3
+2019-05-22,Magnetic ripple domain structure in FeGa/MgO thin films,"The magnetic domain structure is studied in epitaxial
+Fe$_{100-x}$Ga$_x$/MgO(001) films with 0 $<$ x $<$ 30 and thicknesses below 60
+nm by magnetic force microscopy. For low gallium content, domains with the
+magnetization lying in the film plane and domain walls separating micrometric
+areas are observed. Above x $\approx$ 20, the magnetic contrast shows a fine
+corrugation, ranging from 300 to 900 nm, suggesting a ripple substructure with
+a periodic oscillation of the magnetization. We discuss the presence of a
+random magnetic anisotropy contribution, that superimposed to the cubic
+coherent anisotropy, is able to break the uniform orientation of the
+magnetization. The origin of that random anisotropy is attributed to several
+factors: coexistence of crystal phases in the films, inhomogeneous distribution
+of both internal strain and Ga-Ga next nearest neighbor pairs and interface
+magnetic anisotropy due to the Fe-O bond.",1905.09180v2
+2019-06-06,Interaction-dependent anisotropy of fractional quantum Hall states,"A fractional quantum Hall (FQH) system with broken rotational symmetry
+exploits its geometric degree of freedom to minimize its ground state energy.
+The mass anisotropy of bare particles interacting isotropically is partially
+inherited by the many-body FQH state, and the extent to which it does so
+depends on the type of interaction, filling fraction and ground state phase.
+Using numerical infinite density matrix renormalization group simulations, we
+investigate the transference of elliptical ($C_2$-symmetric) anisotropy from
+the band mass of the bare particles to the FQH states, for various power law
+interactions. We map out the response of FQH states to small anisotropy as a
+function of power law exponent, filling, and statistics (bosonic or fermionic)
+of the constituents. Interestingly, we find a non-analyticity in the linear
+response of the FQH state at a special filling-dependent value of the power law
+exponent, above which the interaction effectively becomes zero-range
+(point-like). We also investigate the the effect of $C_4$-symmetric band
+distortions, where we observe a strikingly different dependence on filling.",1906.02835v1
+2019-06-20,High-energy cosmic rays from compact galactic star clusters: particle fluxes and anisotropy,"It has been shown that supernova blast waves interacting with winds from
+massive stars in compact star clusters may be capable of producing cosmic-ray
+(CR) protons to above $10^{17}$ eV. We give a brief description of the
+colliding-shock-flows mechanism and look at generalizations of the diffusion of
+~ 100 PeV CRs in the turbulent galactic magnetic field present in the galactic
+disk. We calculate the temporal evolution of the CR anisotropy from a possible
+distribution of young compact massive star clusters assuming the sources are
+intermittent on time scales of a few million years, i.e., comparable to their
+residence time in the Milky Way. Within the confines of our model, we determine
+the galactic/extra-galactic fraction of high-energy CRs resulting in
+anisotropies consistent with observed values. We find that galactic star
+clusters may contribute a substantial fraction of ~ 100 PeV CRs without
+producing anisotropies above observed limits.",1906.08813v1
+2019-06-23,Effect of elastic anisotropy on phase separation in ternary alloys: A phase-field study,"The precipitate shape, size and distribution are crucial factors which
+determine the properties of several technologically important alloys. Elastic
+interactions between the inclusions modify their morphology and align them
+along elastically favourable crystallographic directions. Among the several
+factors contributing to the elastic interaction energy between precipitating
+phases, anisotropy in elastic moduli is decisive in the emergence of modulated
+structures during phase separation in elastically coherent alloy systems. We
+employ a phase-field model incorporating elastic interaction energy between the
+misfitting phases to study microstructural evolution in ternary three-phase
+alloy systems when the elastic moduli are anisotropic. The spatiotemporal
+evolution of the composition field variables is governed by solving a set of
+coupled Cahn-Hilliard equations numerically using a semi-implicit Fourier
+spectral technique. We methodically vary the misfit strains, alloy chemistry
+and elastic anisotropy to investigate their influence on domain morphology
+during phase separation. The coherency strains between the phases and alloy
+composition alter the coherent phase equilibria and decomposition pathways. The
+degree of anisotropy in elastic moduli modifies the elastic interaction energy
+between the precipitates depending on the sign and magnitude of relative
+misfits, and thus determines the shape and alignment of the inclusions in the
+microstructure.",1906.09637v1
+2019-07-03,Large spin-relaxation anisotropy in bilayer-graphene/WS$_2$ heterostructures,"We study spin-transport in bilayer-graphene (BLG), spin-orbit coupled to a
+tungsten di sulfide (WS$_2$) substrate, and measure a record spin lifetime
+anisotropy ~40-70, i.e. ratio between the out-of-plane $\tau_{\perp}$ and
+in-plane spin relaxation time $\tau_{||}$. We control the injection and
+detection of in-plane and out-of-plane spins via the shape-anisotropy of the
+ferromagnetic electrodes. We estimate $\tau_{\perp}$ ~ 1-2 ns via Hanle
+measurements at high perpendicular magnetic fields and via a new tool we
+develop: Oblique Spin Valve measurements. Using Hanle spin-precession
+experiments we find a low $\tau_{||}$ ~ 30 ps in the electron-doped regime
+which only weakly depends on the carrier density in the BLG and conductivity of
+the underlying WS$_2$, indicating proximity-induced spin-orbit coupling (SOC)
+in the BLG. Such high $\tau_{\perp}$ and spin lifetime anisotropy are clear
+signatures of strong spin-valley coupling for out-of-plane spins in BLG/WS$_2$
+systems in the presence of SOC, and unlock the potential of BLG/transition
+metal dichalcogenide heterostructures for developing future spintronic
+applications.",1907.01975v1
+2019-07-08,Metadynamics study of the temperature dependence of magnetic anisotropy and spin-reorientation transitions in ultrathin films,"We employ metadynamics simulations to calculate the free energy landscape of
+thin ferromagnetic films and perform a systematic study of the temperature
+dependence of magnetic anisotropy and of the spin-reorientation transitions. By
+using a simple spin model we recover the well-known power-law behavior of the
+magnetic anisotropy energy against magnetization and present a rather detailed
+analysis of the spin-reorientation transitions in ultrathin films. Based on
+tensorial exchange interactions and anisotropy parameters derived from
+first-principles calculations we perform simulations for Fe double layers
+deposited on Au(001) and W(110). In case of Fe$_2$W(110) our simulations
+display an out-of-plane to in-plane spin-reorientation transition in agreement
+with experiments.",1907.03616v1
+2019-07-17,Suppression of twinning and enhanced electronic anisotropy of SrIrO3 films,"The spin-orbit coupling and electron correlation in perovskite SrIrO3 (SIO)
+strongly favor new quantum states and make SIO very attractive for next
+generation quantum information technology. In addition, the small electronic
+band-width offers the possibility to manipulate anisotropic electronic
+transport by strain. However, twinned film growth of SIO often masks electronic
+anisotropy which could be very useful for device applications. We demonstrate
+that the twinning of SIO films on (001) oriented SrTiO3 (STO) substrates can be
+strongly reduced for thin films with thickness t less than 30 nm by using
+substrates displaying a TiO2-terminated surface with step-edge alignment
+parallel to the a- or b-axis direction of the substrate. This allows us to
+study electronic anisotropy of strained SIO films which hitherto has been
+reported only for bulk-like SIO. For films with t < 30 nm electronic anisotropy
+increases with increasing t and becomes even twice as large compared to nearly
+strain-free films grown on (110) DyScO3. The experiments demonstrate the high
+sensitivity of electronic transport towards structural distortion and the
+possibility to manipulate transport by substrate engineering.",1907.07520v1
+2019-07-27,Magnetization plateau of the $S=2$ antiferromagnetic Heisenberg chain with anisotropies,"We investigate the $S=2$ antiferromagnetic quantum spin chain with the
+exchange and single-ion anisotropies in a magnetic field, using the numerical
+exact diagonalization of finite-size clusters and the level spectroscopy
+analysis. It is found that a magnetization plateau possibly appears at a half
+of the saturation magnetization for some suitable anisotropy parameters. The
+level spectroscopy analysis indicates that the 1/2 magnetization plateau is
+formed by two different mechanisms, depending on the anisotropy parameters. The
+phase diagram of the 1/2 plateau states and some typical magnetization curves
+are also presented. In addition the biquadratic interaction is revealed to
+enhance the plateau induced by the Haldane mechanism.",1907.11931v2
+2019-08-01,Anisotropies and non-Gaussianity of the Cosmological Gravitational Wave Background,"The Stochastic Gravitational Wave Background (SGWB) is expected to be a key
+observable for Gravitational Wave (GW) interferometry. Its detection will open
+a new window on early universe cosmology and on the astrophysics of compact
+objects. Using a Boltzmann approach, we study the angular anisotropies of the
+GW energy density, which is an important tool to disentangle the different
+cosmological and astrophysical contributions to the SGWB. Anisotropies in the
+cosmological background are imprinted both at its production, and by GW
+propagation through the large-scale scalar and tensor perturbations of the
+universe. The first contribution is not present in the Cosmic Microwave
+Background (CMB) radiation (as the universe is not transparent to photons
+before recombination), causing an order one dependence of the anisotropies on
+frequency. Moreover, we provide a new method to characterize the cosmological
+SGWB through its possible deviation from a Gaussian statistics. In particular,
+the SGWB will become a new probe of the primordial non-Gaussianity of the
+large-scale cosmological perturbations.",1908.00527v1
+2019-09-23,Criticality of the $O(2)$ model with cubic anisotropies from nonperturbative renormalization,"We study the $O(2)$ model with $\mathbb{Z}_4$-symmetric perturbations within
+the framework of nonperturbative renormalization group (RG) for spatial
+dimensionality $d=2$ and $d=3$. In a unified framework we resolve the
+relatively complex crossover behavior emergent due to the presence of multiple
+RG fixed points. In $d=3$ the system is controlled by the $XY$, Ising, and
+low-$T$ fixed points in presence of a dangerously irrelevant anisotropy
+coupling $\lambda$. In $d=2$ the anisotropy coupling is marginal and the
+physical picture is governed by the interplay between two distinct lines of RG
+fixed points, giving rise to nonuniversal critical behavior; and an isolated
+Ising fixed point. In addition to inducing crossover behavior in universal
+properties, the presence of the Ising fixed point yields a generic, abrupt
+change of critical temperature at a specific value of the anisotropy field.",1909.10600v1
+2019-09-30,Effects of exchange and weak Dzyaloshinsky-Moriya anisotropies on thermodynamic characteristics of spin-gapped magnets,"We study the modification of low temperature properties of quantum magnets
+such as magnetization, heat capacity, energy spectrum, and densities of
+condensed and noncondensed quasiparticles (triplons) due to anisotropies in the
+framework of mean-field based approach. We show that in contrast to exchange
+anisotropy (EA) interaction, Dzyaloshinsky-Moriya (DM) interaction modifies the
+physics dramatically. Particularly, it changes the sign of the anomalous
+density in the whole range of temperatures. Its critical behavior is slightly
+modified also by the EA. We have found that the shift of the critical
+temperature of phase transition (or crossover caused by DM interaction) is
+positive and significant. Using the experimental data on the magnetization of
+the compound TlCuCl$_3$, we have found optimal values for the strengths of EA
+and DM interactions. The spectrum of the energy of low lying excitations has
+also been investigated and found to develop a linear dispersion similar to
+Goldstone mode with a negligibly small anisotropy gap.",1909.13641v2
+2019-10-25,Local magnetic anisotropy by polarized neutron powder diffraction: application of magnetically induced preferred crystallite orientation,"Polarized neutron diffraction allows to determine the local susceptibility
+tensor on the magnetic site both in single crystals and powders. It is widely
+used in the studies of single crystals, but it is still hardly applicable to a
+number of highly interesting powder materials, like molecular magnets or
+nanoscale systems because of the low luminosity of existing instruments and the
+absence of an appropriate data analysis software. We show that these
+difficulties can be overcome by using a large area detector in combination with
+the two-dimensional Rietveld method and powder samples with magnetically
+induced preferred crystallite orientation. This is demonstrated by revisiting
+two test powder compounds, namely, low anisotropy (soft) ferrimagnetic compound
+Fe3O4 and spin-ice compound Ho2Ti2O7 with high local anisotropy. The values of
+magnetic moments in Fe3O4 and the susceptibility tensors of Ho2Ti2O7 at various
+temperatures and fields were found in perfect agreement with these found
+earlier in single crystal experiments. The magnetically induced preferred
+crystallite orientation was used to study the local susceptibility of a
+single-molecule magnet Co([(CH3)2N]2CS)2Cl2. Hence, the studies of local
+magnetic anisotropy in powder systems might now become accessible.",1910.11822v1
+2019-10-30,"Anomalous Gravitational TTT Vertex, Temperature Inhomogeneity, and Pressure Anisotropy","The conformal anomaly in curved spacetime generates a nontrivial anomalous
+vertex, given by the three-point correlation function $TTT$ of the
+energy-momentum tensor $T^{\mu\nu}$. We show that a temperature inhomogeneity
+in a gas of charged massless particles generates, via the $TTT$ vertex, a
+pressure anisotropy with respect to the axis of the temperature variation. This
+very particular signature may provide an experimental access to the elusive
+gravitational coefficient $b$ which determines the anomaly contribution of the
+Weyl tensor to the trace of the energy-momentum tensor in curved spacetime. We
+present an estimate of the pressure anisotropy both for fermionic
+quasiparticles in the solid-state environment of Dirac semimetals as well as
+for a quark-gluon plasma in relativistic heavy-ion collisions. In both cases,
+the pressure anisotropy is small compared to the mean thermal pressure.",1910.13727v3
+2019-11-26,Preserving the accuracy of numerical methods discretizing anisotropic elliptic problems,"In this paper we study the loss of precision of numerical methods
+discretizing anisotropic problems and propose alternative approaches free from
+this drawback. The deterioration of the accuracy is observed when the
+coordinates and the mesh are unrelated to the anisotropy direction. While this
+issue is commonly addressed by increasing the scheme approximation order, we
+demonstrate that, though the gains are evident, the precision of these
+numerical methods remain far from optimal and limited to moderate anisotropy
+strengths. This is analysed and explained by an amplification of the
+approximation error related to the anisotropy strength. We propose an approach
+consisting in the introduction of an auxiliary variable aimed at removing the
+amplification of the discretization error. By this means the precision of the
+numerical approximation is demonstrated to be independent of the anisotropy
+strength.",1911.11482v1
+2019-11-29,Reflection anisotropy experiments to study non-equilibrium dynamics of electronic nematicity,"Electronic nematicity have attracted a great deal of interest in the
+unconventional superconductivity research. We present an experimental method to
+investigate reflectivity anisotropy by the electronic nematicity and its
+non-equilibrium dynamics. Our experimental results on
+Ba(Fe$_{0.955}$Co$_{0.045}$)$_{2}$As$_{2}$ single crystal clearly feature the
+broken four-fold symmetry along directions parallel to Fe-Fe bonding. Numerical
+simulations using WVASE from Woollam Co. demonstrate that our method is highly
+reliable under various experimental conditions. Finally, we perform
+time-resolved reflectivity anisotropy measurement confirming that
+photo-excitation by 1.55 eV photons suppresses the reflectivity anisotropy due
+to nematic order.",1911.12920v1
+2019-12-19,Characterizing the Cosmological Gravitational Wave Background Anisotropies and non-Gaussianity,"A future detection of the Stochastic Gravitational Wave Background (SGWB)
+with GW experiments is expected to open a new window on early universe
+cosmology and on the astrophysics of compact objects. In this paper we study
+SGWB anisotropies, that can offer new tools to discriminate between different
+sources of GWs. In particular, the cosmological SGWB inherits its anisotropies
+both (i) at its production and (ii) during its propagation through our
+perturbed universe. Concerning (i), we show that it typically leads to
+anisotropies with order one dependence on frequency. We then compute the effect
+of (ii) through a Boltzmann approach, including contributions of both
+large-scale scalar and tensor linearized perturbations. We also compute for the
+first time the three-point function of the SGWB energy density, which can allow
+one to extract information on GW non-Gaussianity with interferometers. Finally,
+we include non-linear effects associated with long wavelength scalar
+fluctuations, and compute the squeezed limit of the 3-point function for the
+SGWB density contrast. Such limit satisfies a consistency relation,
+conceptually similar to what found in the literature for the case of CMB
+perturbations.",1912.09433v1
+2019-12-22,"Two-dimensional O(n) Models with Defects of ""Random Local Anisotropy"" Type","The phase diagram of two-dimensional systems with continuous symmetry of the
+vector order parameter containing defects of the ""random local anisotropy"" type
+is investigated. In the case of a weakly anisotropic distribution of the easy
+anisotropy axes in the space of the order parameter, with decreasing
+temperature, a smooth transition takes place from the paramagnetic phase with
+dynamic fluctuations of the order parameter to the Imri-Ma phase with its
+static fluctuations. In the case when the anisotropic distribution of the easy
+axes induces a global anisotropy of the ""easy axis"" type that exceeds a
+critical value, the system goes into the Ising class of universality, and a
+phase transition to the ordered state occurs in it at a finite temperature.",1912.10444v1
+2019-12-23,Spin-$\frac{1}{2}$ kagome Heisenberg antiferromagnet with strong breathing anisotropy,"We study the zero-temperature phase diagram of the spin-$\frac{1}{2}$
+Heisenberg model with breathing anisotropy (i.e., with different coupling
+strength on the upward and downward triangles) on the kagome lattice. Our study
+relies on large scale tensor network simulations based on infinite projected
+entangled-pair state and infinite projected entangled-simplex state methods
+adapted to the kagome lattice. Our energy analysis suggests that the U(1)
+algebraic quantum spin-liquid (QSL) ground-state of the isotropic Heisenberg
+model is stable up to very large breathing anisotropy until it breaks down to a
+critical lattice-nematic phase that breaks rotational symmetry in real space
+through a first-order quantum phase transition. Our results also provide
+further insight into the recent experiment on vanadium oxyfluoride compounds
+which has been shown to be relevant platforms for realizing QSL in the presence
+of breathing anisotropy.",1912.10756v2
+2020-01-06,Galactic Magnetic Field Bias on Inferences from UHECR Data,"A consequence of Liouville's theorem indicates that the recently observed
+large scale anisotropy in the arrival direction of Ultra-High-Energy Cosmic
+Rays (UHECRs) cannot be produced by the Galactic magnetic field, thus this
+anisotropy already needs to be present outside our Galaxy. But in this case,
+the observed energy spectrum and composition of UHECRs differs from the one
+outside of the Milky Way, due to the suppression or the amplification of the
+UHECR flux from certain directions by the Galactic magnetic field. In this
+work, we investigate this effect for the case of a dipole and a quadrupole
+anisotropy, respectively, for the widely-used JF12 magnetic field model. We
+investigate boundaries on the maximal amplitude of the observed anisotropy and
+the maximal charge number of UHECRs. Furthermore, the flux modification is
+discussed in the light of the Auger data on the recent dipole and also the
+chemical composition. We find that this modification effect yields a
+modification of the observed flux of up to $\sim 10\%$ for the investigated
+magnetic field model and the observed dipole, in particular for a heavy
+chemical composition of UHECRs as suggested by the 'EPOS-LHC' model.",2001.01530v2
+2020-01-14,Low power switching of magnetization using enhanced magnetic anisotropy with short-voltage-pulse application,"A low power magnetization switching scheme based on the voltage control of
+magnetic anisotropy (VCMA) is proposed. In contrast to the conventional
+switching scheme using VCMA, where the magnetic anisotropy is eliminated during
+the voltage pulse, the magnetic anisotropy is enhanced to induce precession
+around the axis close to the easy axis. After turning off the voltage
+proximately at a half of precession period, the magnetization relaxes to the
+opposite equilibrium direction. We perform numerical simulations and show that
+the pulse duration of the proposed switching scheme is as short as a few tens
+of pico seconds. Such a short pulse duration is beneficial for low power
+consumption because of the reduction of energy loss by Joule heating.",2001.11088v1
+2020-03-31,Discrimination of Dark Matter Mass and Velocity Distribution by Directional Detection,"Velocity distribution of dark matter is assumed to be isotropic in most
+cases, however, anisotropy is suggested in some simulations. Directional direct
+detection of dark matter is a hopeful way to discriminate the anisotropy of
+dark matter velocity distribution. We simulate the dark matter and target
+scattering in the directional direct detection, and investigate conditions
+required to discriminate the anisotropy. If dark matter mass is known,
+$O(10^3)-O(10^4)$ events are required for the discrimination if the dark matter
+mass is known by other experiments. We also study the case that the dark matter
+mass is not known, and in analysis using both the recoil energy and the
+scattering angle data, both the dark matter mass and the anisotropy can be
+restricted much better than the analysis only with either of them.",2003.14220v1
+2020-04-03,Spin-Excitations Anisotropy in the Bilayer Iron-Based Superconductor CaKFe$_4$As$_4$,"We use polarized inelastic neutron scattering to study the spin-excitations
+anisotropy in the bilayer iron-based superconductor CaKFe$_4$As$_4$ ($T_c$ = 35
+K). In the superconducting state, both odd and even $L-$modulations of spin
+resonance have been observed in our previous unpolarized neutron scattering
+experiments (T. Xie {\it et al.} Phys. Rev. Lett. {\bf 120}, 267003 (2018)).
+Here we find that the high-energy even mode ($\sim 18$ meV) is isotropic in
+spin space, but the low-energy odd modes consist of a $c-$axis polarized mode
+around 9 meV along with another partially overlapped in-plane mode around 12
+meV. We argue that such spin anisotropy is induced by the spin-orbit coupling
+in the spin-vortex-type fluctuations of this unique compound. The spin
+anisotropy is strongly affected by the superconductivity, where it is weak
+below 6 meV in the normal state and then transferred to higher energy and
+further enhanced in the odd mode of spin resonance below $T_c$.",2004.01405v1
+2020-04-06,Growth morphology and symmetry selection of interfacial instabilities in anisotropic environments,"The displacement of a fluid by another less viscous one in a quasi-two
+dimensional geometry typically leads to complex fingering patterns. In an
+isotropic system, dense-branching growth arises, which is characterized by
+repeated tip-splitting of evolving fingers. When anisotropy is present in the
+interfacial dynamics, the growth morphology changes to dendritic growth
+characterized by regular structures. We introduce anisotropy by engraving a
+six-fold symmetric lattice of channels on a Hele-Shaw cell. We show that the
+morphology transition in miscible fluids depends not only on the previously
+reported degree of anisotropy set by the lattice topography, but also on the
+viscosity ratio between the two fluids. Remarkably, the viscosity ratio and the
+degree of anisotropy also govern the global features of the dendritic patterns,
+inducing a systematic change from six-fold towards twelve-fold symmetric
+dendrites. Varying either control parameter provides a new method to tune the
+symmetry of complex patterns, which may also have relevance for analogous
+phenomena of gradient-driven interfacial dynamics, such as directional
+solidification or electrodeposition.",2004.02371v2
+2020-04-06,Theoretical Study of the Anisotropy Spectra of the Valine Zwitterion and Glyceraldehyde,"The electronic absorption (EA), circular dichroism (ECD), and anisotropy
+spectra of the L-valine zwitterion and D-glyceraldehyde are calculated by
+time-dependent density functional theory (TDDFT) with the M06-2X and B3LYP
+functionals. It is found that the absorption and ECD spectra from TDDFT/M06-2X
+agree well with experimental results measured from amorphous film of L-valine.
+Moreover, the calculations reproduce all three major peaks observed in the
+experimental anisotropy spectra. For D-glyceraldehyde, the TDDFT/M06-2X
+calculations indicate that the excitation wavelengths of the first excited
+state of 32 stable conformers distribute from 288 to 322 nm, giving rise to two
+ECD peaks with opposite signs centered at 288 nm and 322 nm. The very weak
+absorption of the first excited state (S1) induces two high peaks in the
+anisotropy spectra of D-glyceraldehyde, which should be seen in future
+experimental works.",2004.02455v3
+2020-04-21,Magnetization plateaux cascade in the frustrated quantum antiferromagnet Cs$_2$CoBr$_4$,"We have found an unusual competition of two frustration mechanisms in the 2D
+quantum antiferromagnet Cs$_2$CoBr$_4$. The key actors are the alternation of
+single-ion planar anisotropy direction of the individual magnetic Co$^{2+}$
+ions, and their arrangement in a distorted triangular lattice structure. In
+particular, the uniquely oriented Ising-type anisotropy emerges from the
+competition of easy-plane ones, and for a magnetic field applied along this
+axis one finds a cascade of five ordered phases at low temperatures. Two of
+these phases feature magnetization plateaux. The low-field one is supposed to
+be a consequence of a collinear ground state stabilized by the anisotropy,
+while the other plateau bears characteristics of an ""up-up-down"" state
+exclusive for lattices with triangular exchange patterns. Such coexistence of
+the magnetization plateaux is a fingerprint of competition between the
+anisotropy and the geometric frustration in Cs$_2$CoBr$_4$.",2004.09893v2
+2020-04-25,Pulse-assisted magnetization switching in magnetic nanowires at picosecond and nanosecond timescales with low energy,"Detailed understanding of spin dynamics in magnetic nanomaterials is
+necessary for developing ultrafast, low-energy and high-density spintronic
+logic and memory. Here, we develop micromagnetic models and analytical
+solutions to elucidate the effect of increasing damping and uniaxial anisotropy
+on magnetic field pulse-assisted switching time, energy and field requirements
+of nanowires with perpendicular magnetic anisotropy and yttrium iron
+garnet-like spin transport properties. A nanowire is initially magnetized using
+an external magnetic field pulse (write) and self-relaxation. Next, magnetic
+moments exhibit deterministic switching upon receiving 2.5 ns-long external
+magnetic pulses in both vertical polarities. Favorable damping
+({\alpha}~0.1-0.5) and anisotropy energies (10^4-10^5 J m^-3) allow for as low
+as picosecond magnetization switching times. Magnetization reversal with fields
+below coercivity was observed using spin precession instabilities. A
+competition or a nanomagnetic trilemma arises among the switching rate, energy
+cost and external field required. Developing magnetic nanowires with optimized
+damping and effective anisotropy could reduce the switching energy barrier down
+to 3163kBT at room temperature. Thus, pulse-assisted picosecond and low energy
+switching in nanomagnets could enable ultrafast nanomagnetic logic and cellular
+automata.",2004.12243v1
+2020-05-19,Magnetic hard-direction ordering in anisotropic Kondo systems,"We present a generic mechanism that explains why many Kondo materials show
+magnetic ordering along directions that are not favoured by the crystal-field
+anisotropy. Using a renormalization-group (RG) analysis of single impurity
+Kondo models with single-ion anisotropy, we demonstrate that strong
+fluctuations above the Kondo temperature drive a moment re-orientation over a
+wide range of parameters, e.g. for different spin values $S$ and number of
+Kondo channels $N$. In tetragonal systems this can happen for both easy-plane
+or easy axis anisotropy. The characteristic crossing of magnetic
+susceptibilities is not an artefact of the weak-coupling RG treatment but can
+be reproduced in brute-force perturbation theory. Employing numerical
+renormalization group (NRG), we show that for an under-screened moment ($S=1$,
+$N=1$) with easy-plane anisotropy, a crossing of magnetic susceptibilities can
+also occur in the strong-coupling regime (below the Kondo temperature). This
+suggests that collective magnetic ordering of such under-screened moments would
+develop along the magnetic hard axis.",2005.09533v3
+2020-05-22,The nonlinear patterns of the cosmic anisotropy in the late time universe,"In this manuscript, we investigate the patterns satisfied by the cosmological
+anisotropy under the hypothesis of the observers being co-moving with a perfect
+fluid whose induced space sections are homogeneous with vanishing scalar
+curvature. We describe the positive increment $\Delta R$ that the Hubble
+parameter in the anisotropic model will have as it is compared to its isotropic
+counterpart. In general, it has an exponential awakening at a specific redshift
+$z_A$. We also show that the deceleration and the jerk along the principal
+directions of the anisotropy are constrained by simple algebraic equations that
+do not depend on the type of matter present. These characteristic patterns form
+a valuable framework to distinguish the cosmological anisotropy from any other
+kind, thus adding a useful tool to probe its upper limits in the supernovae
+surveys, which are orders of magnitude away from those observed in the CMB.",2005.11250v2
+2020-05-26,Classifying local anisotropy formed by rigid molecules: symmetries and tensors,"We consider an infinitesimal volume where there are many rigid molecules of
+the same kind, and discuss the description and classification of the local
+anisotropy in this volume by tensors. First, we examine the symmetry of a rigid
+molecule, which is described by a point group in $SO(3)$. For each point group
+in $SO(3)$, we find the tensors invariant under the rotations in the group.
+These tensors shall be symmetric and traceless. We write down the explicit
+expressions. The order parameters to describe the local anisotropy are then
+chosen as some of the invariant tensors averaged about the density function.
+Next, we discuss the classification of local anisotropy by the symmetry of the
+whole infinitesimal volume. This mesoscopic symmetry can be recognized by the
+value of the order parameter tensors in the sense of maximum entropy state. For
+some sets of order parameter tensors involving different molecular symmetries,
+we give the classification of mesoscopic symmetries, in which the three-fold,
+four-fold and polyhedral symmetries are examined.",2005.12480v1
+2020-06-22,Spin-orbit torque induced magnetisation dynamics and switching in CoFeB/Ta/CoFeB system with mixed magnetic anisotropy,"Spin-orbit torque (SOT) induced magnetisation switching in CoFeB/Ta/CoFeB
+trilayer with two CoFeB layers exhibiting in-plane magnetic anisotropy (IPMA)
+and perpendicular magnetic anisotropy (PMA) is investigated. Interlayer
+exchange coupling (IEC), measured using ferromagnetic resonance technique is
+modified by varying thickness of Ta spacer. The evolution of the IEC leads to
+different orientation of the magnetic anisotropy axes of two CoFeB layers: for
+thicker Ta layer where magnetisation prefers antiferromagnetic ordering and for
+thinner Ta layer where ferromagnetic coupling exists. Magnetisation state of
+the CoFeB layer exhibiting PMA is controlled by the spin-polarized current
+originating from SOT in $\mu m$ sized Hall bars. The evolution of the critical
+SOT current density with Ta thickness is presented, showing an increase with
+decreasing $t_\mathrm{Ta}$, which coincides with the coercive field dependence.
+In a narrow range of $t_\mathrm{Ta}$ corresponding to the ferromagnetic IEC,
+the field-free SOT-induced switching is achieved.",2006.12068v1
+2020-07-08,Anisotropic properties of monolayer 2D materials: an overview from the C2DB database,"We analyze the occurrence of in-plane anisotropy in the electronic, magnetic,
+elastic and transport properties of more than one thousand 2D materials from
+the C2DB database. We identify hundreds of anisotropic materials and classify
+them according to their point group symmetry and degree of anisotropy. A
+statistical analysis reveals that a lower point group symmetry and a larger
+amount of different elements in the structure favour all types of anisotropies,
+which could be relevant for future materials design approaches. Besides, we
+identify novel compounds, predicted to be easily exfoliable from a parent bulk
+compound, with anisotropies that largely outscore those of already known 2D
+materials. Our findings provide a comprehensive reference for future studies of
+anisotropic response in atomically-thin crystals and point to new previously
+unexplored materials for the next generation of anisotropic 2D devices.",2007.04152v2
+2020-07-08,Susceptibility anisotropy and its disorder evolution in models for Kitaev materials,"Mott insulators with strong spin-orbit coupling display a strongly
+anisotropic response to applied magnetic fields. This applies in particular to
+Kitaev materials, with $\alpha$-RuCl$_3$ and Na$_2$IrO$_3$ representing two
+important examples. Both show a magnetically ordered zigzag state at low
+temperatures, and considerable effort has been devoted to properly modeling
+these systems in order to identify routes towards realizing a quantum spin
+liquid. Here, we investigate the relevant Heisenberg-Kitaev-$\Gamma$ model
+primarily at elevated temperatures, focusing on the characteristic anisotropy
+between the in-plane and out-of-plane uniform susceptibility. For
+$\alpha$-RuCl$_3$, we find that the experimentally observed anisotropy,
+including its temperature dependence, can be reproduced by combining a large
+off-diagonal $\Gamma_1$ coupling with a moderate $g$-factor anisotropy.
+Moreover, we study in detail the effect of magnetic dilution and provide
+predictions for the doping evolution of the temperature-dependent
+susceptibilities.",2007.04339v2
+2020-07-21,Orbital anisotropy of heavy fermion Ce$_{2}$IrIn$_{8}$ under crystalline electric field and its energy scale,"We investigate the temperature ($T$)-evolution of orbital anisotropy and its
+effect on spectral function and optical conductivity in Ce$_{2}$IrIn$_{8}$,
+using a first principles dynamical mean field theory combined with density
+functional theory. The orbital anisotropy develops by lowering $T$ and it is
+intensified below a temperature corresponding to the crystalline-electric field
+(CEF) splitting size. Interestingly, the depopulation of CEF excited states
+leaves a spectroscopic signature, ""shoulder"", in the $T$-dependent spectral
+function at the Fermi level. From the two-orbital Anderson impurity model, we
+demonstrate that CEF splitting size is the key ingredient influencing the
+emergence and the position of the ""shoulder"". Besides the two conventional
+temperature scales $T_{K}$ and $T^{*}$, we introduce an additional temperature
+scale to deal with the orbital anisotropy in heavy fermion systems.",2007.10641v3
+2020-08-07,Voltage-controlled magnetic anisotropy in antiferromagnetic MgO-capped MnPt films,"The magnetic anisotropy in MgO-capped MnPt films and its voltage control are
+studied using first-principles calculations. Sharp variation of the magnetic
+anisotropy with film thickness, especially in the Pt-terminated film, suggests
+that it may be widely tuned by adjusting the film thickness. In thick films the
+linear voltage control coefficient is as large as 1.5 and $-0.6$ pJ/Vm for
+Pt-terminated and Mn-terminated interfaces, respectively. The combination of a
+widely tunable magnetic anisotropy energy and a large voltage-control
+coefficient suggest that MgO-capped MnPt films can serve as a versatile
+platform for magnetic memory and antiferromagnonic applications.",2008.03249v2
+2020-08-12,"Equilibrium, radial stability and non-adiabatic gravitational collapse of anisotropic neutron stars","In this work we construct families of anisotropic neutron stars for an
+equation of state compatible with the constraints of the gravitational-wave
+event GW170817 and for four anisotropy ansatze. Such stars are subjected to a
+radial perturbation in order to study their stability against radial
+oscillations and we develop a dynamical model to describe the non-adiabatic
+gravitational collapse of the unstable anisotropic configurations whose
+ultimate fate is the formation of a black hole. We find that the standard
+criterion for radial stability $dM/d\rho_c >0$ is not always compatible with
+the calculation of the oscillation frequencies for some anisotropy ansatze, and
+each anisotropy parameter is constrained taking into account the recent
+restriction of maximum mass of neutron stars. We further generalize the TOV
+equations within a non-adiabatic context and we investigate the dynamical
+behaviour of the equation of state, heat flux, anisotropy factor and mass
+function as an unstable anisotropic star collapses. After obtaining the
+evolution equations we recover, as a static limit, the background equations.",2008.05331v1
+2020-09-09,Magnetic Anisotropy in Spin-3/2 with Heavy Ligand in Honeycomb Mott Insulators: Application to CrI$_3$,"Ferromagnetism in the two-dimensional CrI$_3$ has generated a lot of
+excitement, and it was recently proposed that the spin-orbit coupling (SOC) in
+Iodine may generate bond-dependent spin interactions leading to magnetic
+anisotropy. Here we derive a microscopic spin model of S=3/2 on transition
+metals surrounded by heavy ligands in honeycomb Mott insulators using a
+strong-coupling perturbation theory. For ideal octahedra we find Heisenberg and
+Kitaev interactions, which favor the magnetic moment along the cubic axis via
+quantum fluctuations. When a slight trigonal distortion of the octahedra is
+present together with the SOC, three additional interactions arise, comprised
+of the off-diagonal symmetric $\Gamma$ and $\Gamma^\prime$, and single-ion
+anisotropy. The resulting magnetic anisotropy pins the moment perpendicular to
+the honeycomb plane as observed in a single-layer of CrI$_3$, suggesting the
+significance of SOC and trigonal distortion in understanding magnetism of two
+dimensional Mott insulators. Comparison to the spin-orbit coupled $J_{\rm
+eff}$= 1/2 and S=1 models is also presented.",2009.04475v2
+2020-10-01,Charge density waves and their transitions in anisotropic quantum Hall systems,"In recent experiments, external anisotropy has been a useful tool to tune
+different phases and study their competitions. In this paper, we look at the
+quantum Hall charge density wave states in the $N=2$ Landau level. Without
+anisotropy, there are two first-order phase transitions between the Wigner
+crystal, the $2$-electron bubble phase, and the stripe phase. By adding mass
+anisotropy, our analytical and numerical studies show that the $2$-electron
+bubble phase disappears and the stripe phase significantly enlarges its domain
+in the phase diagram. Meanwhile, a regime of stripe crystals that may be
+observed experimentally is unveiled after the bubble phase gets out. Upon
+increase of the anisotropy, the energy of the phases at the transitions becomes
+progressively smooth as a function of the filling. We conclude that all
+first-order phase transitions are replaced by continuous phase transitions,
+providing a possible realisation of continuous quantum crystalline phase
+transitions.",2010.00611v2
+2020-10-05,"Properties of amorphous CoZr(RE) (RE=Gd, Sm, Dy) films with various uniaxial anisotropies, prepared by a new process","If a DC magnetic field is applied parallel to the plane of amorphous CoZr(RE)
+thin films during sputter depositing, a uniaxial anisotropy is formed the
+direction of which depends upon the choice of RE substituted and its
+concentration. When RE = Gd a perpendicular anisotropy K, forms over a large
+concentration range, a spin reorientation process being at the origin of the
+process. A well-defined K, is developed also in CoFeZrGd and CoZrGdSm films.
+CoZrGdDy films exhibit simultaneously a perpendicular and an in-plane uniaxial
+anisotropy. The related magnetization process and domain structures are quite
+peculiar.",2010.01831v1
+2020-10-30,"Phase transitions between helices, vortices, and hedgehogs driven by spatial anisotropy in chiral magnets","Superpositions of spin helices can yield topological spin textures, such as
+two-dimensional vortices and skyrmions, and three-dimensional hedgehogs. Their
+topological nature and spatial dimensionality depend on the number and relative
+directions of the constituent helices. This allows mutual transformation
+between the topological spin textures by controlling the spatial anisotropy.
+Here we theoretically study the effect of anisotropy in the magnetic
+interactions for an effective spin model for chiral magnetic metals. By
+variational calculations for both cases with triple and quadruple
+superpositions, we find that the hedgehog lattices, which are stable in the
+isotropic case, are deformed by the anisotropy, and eventually changed into
+other spin textures with reduced dimension, such as helices and vortices. We
+also clarify the changes of topological properties by tracing the real-space
+positions of magnetic monopoles and antimonopoles as well as the emergent
+magnetic field generated by the noncoplanar spin textures. Our results suggest
+possible control of the topological spin textures, e.g., by uniaxial pressure
+and chemical substitution in chiral materials.",2010.16187v1
+2020-11-04,Large angle precession of magnetization maintained by a microwave voltage,"Effects of a microwave voltage on magnetization precession are analyzed based
+on a macrospin model. The microwave voltage induces the oscillating anisotropy
+field through the voltage controlled magnetic anisotropy (VCMA) effect, and
+then stimulates the magnetization. The large angle precession is maintained if
+the magnetization synchronizes with the microwave voltage. The effective
+equations of motion of the magnetization with an oscillating anisotropy field
+are derived, and the mechanism of the synchronization is clarified by analyzing
+the derived equations of motion. The conditions of the angular frequency
+detuning and the amplitude of the oscillating anisotropy field for
+synchronization are obtained. The results are useful for development of the
+VCMA-based energy-efficient spintronics devices using magnetization precession
+such as a VCMA-based magnetoresistive random access memory and a nano-scale
+microwave magnetic field generator.",2011.02104v1
+2020-11-05,Antiferromagnetic resonance in a spin-gap magnet with strong single-ion anisotropy,"Quasi-one-dimensional magnet NiCl$_2\cdot$4SC(NH$_2$)$_2$, usually
+abbreviated as DTN, does not order at zero field down to $T=0$: due to the
+strong single-ion anisotropy of the ""easy plane"" type acting on $S=1$ Ni$^{2+}$
+ions, the $S_z=0$ ground state is separated from $S_z=\pm 1$ excitations by an
+energy gap. Once the magnetic field is applied along the main anisotropy axis,
+the gap closes at $B_{c1}=2.18$ T and the field-induced antiferromagnetic order
+arises. The low-energy excitations spectrum of this field-induced ordered state
+includes two branches of excitations, one of them have to be a gapless
+Goldstone mode. Recent studies of excitations spectrum in a field-induced
+ordered state of DTN (T.Soldatov et.al, Phys.Rev.B 101, 104410 (2020)) have
+revealed that Goldstone mode became gapped as magnetic field deviates from the
+main symmetry axis. This paper proposes simple description of antiferromagnetic
+resonance modes of quasi-one-dimensional quantum $S=1$ magnet with strong
+single-ion anisotropy. The approach used is based on a combination of the
+strong coupling model for the anisotropic spin chain with the conventional
+mean-field model of antiferromagnetic resonance. The resulting model fits to
+the known experimental results without additional tuning parameters.",2011.02715v1
+2020-11-05,Testing Short Distance Anisotropy in Space,"The isotropy of space is not a logical requirement but rather is an empirical
+question; indeed there is suggestive evidence that universe might be
+anisotropic. A plausible source of these anisotropies could be quantum gravity
+corrections. If these corrections happen to be between the electroweak scale
+and the Planck scale, then these anisotropies can have measurable consequences
+at short distances and their effects can be measured using ultra sensitive
+condensed matter systems. We investigate how such anisotropic quantum gravity
+corrections modify low energy physics through an anisotropic deformation of the
+Heisenberg algebra. We discuss how such anisotropies might be observed using a
+scanning tunneling microscope.",2011.03340v2
+2020-11-06,Covariant formulation of gluon self-energy in presence of ellipsoidal anisotropy,"In this work, a covariant formulation of the gluon self-energy in presence of
+ellipsoidal anisotropy is considered. It is shown that the general structure of
+the gluon self-energy can be written in terms of six linearly independent
+projection tensors. Similar to the spheroidal anisotropy, mass scales can be
+introduced for each of the collective modes considering the static limits. With
+a simplified ellipsoidal generalization of the Romatschke-Strickland form, the
+angular dependencies of the mass scales are studied. It is observed that,
+compared to the spheroidal case, additional unstable mode may appear in
+presence of ellipsoidal anisotropy depending upon the choice of the parameters.",2011.03374v2
+2020-11-14,Voltage-controlled magnetic anisotropy under the electronic structure modulation in quantum wells,"Voltage-controlled magnetic anisotropy (VCMA) offers an emerging approach to
+realize energy-efficient magnetization switching in spintronic devices such as
+magnetic random access memories (MRAMs). Here, we show that manipulating the
+condensed states, i.e., introducing quantum well (QW) can significantly
+influence the VCMA in a Cr/Fe-QW/MgAl2O4 based magnetic tunnel junction (MTJ).
+Only for the MTJ with an even number of Fe atomic layers, we observed a novel
+A-shaped VCMA curve for a particular QW state, where magnetic anisotropy energy
+(MAE) reaches a local maximum at zero bias and reduces when applying both
+positive and negative bias, i.e., a novel bi-polar VCMA effect. Our ab initio
+calculations demonstrate that the QW states give an additional contribution to
+perpendicular magnetic anisotropy (PMA), which can explain not only the
+A-shaped VCMA but also the Fe-layer-number parity dependence of VCMA. The
+present study suggests that the QW-modulated VCMA should open a new pathway to
+design VCMA-assisted MRAM.",2011.07217v1
+2020-11-25,Investigation of superconducting properties and possible nematic superconductivity in self-doped BiCh2-based superconductor CeOBiS1.7Se0.3,"We investigate the superconducting properties and possible nematic
+superconductivity of self-doped BiCh2-based (Ch: S, Se) superconductor
+CeOBiS1.7Se0.3 through the measurements of in-plane anisotropy of
+magnetoresistance. Single crystals of CeOBiS1.7Se0.3 were grown using a flux
+method. Single-crystal structural analysis revealed that the crystal structure
+at room temperature is tetragonal (P4/nmm). Bulk superconductivity with a
+transition temperature of 3.3 K was observed through electrical resistivity and
+magnetization measurements. Investigation of anisotropy of upper critical field
+suggested relatively low anisotropy in the crystal as compared to other
+BiCh2-based superconductors. In the superconducting states of CeOBiS1.7Se0.3,
+two-fold symmetric in-plane anisotropy of magnetoresistance was observed, which
+indicates the in-plane rotational symmetry breaking in the tetragonal structure
+and hence the possibility of nematic superconductivity in CeOBiS1.7Se0.3.",2011.12708v1
+2020-12-24,Relationship between polytropic index and temperature anisotropy in space plasmas,"The paper develops a theoretical relationship between the polytropic index
+and the temperature anisotropy that may characterize space plasmas. The
+derivation is based on the correlation among the kinetic energies of particles
+with velocities described by anisotropic kappa distributions. The correlation
+coefficient depends on the effective dimensionality of the velocity
+distribution function, having its shape determined by the temperature
+anisotropies caused by the ambient magnetic field; on the other hand, the
+effective dimensionality is directly dependent on the polytropic index. This
+analysis leads to the connection between the correlation coefficient, effective
+dimensionality of velocity space, and the polytropic index, with the ratio of
+temperature anisotropy. Moreover, a data and statistical analysis is performed
+to test the application of the theoretically developed model, in the solar wind
+proton plasma near 1 AU. The derived theoretical relationship is in good
+agreement with observations, showing that the lowest and classical value of the
+adiabatic polytropic index occurs in the isotropic case, while higher indices
+characterize anisotropic plasmas. Finally, possible extensions of the theory
+considering (i) non-adiabatic polytropic behavior, and (ii) more general
+distributions, are further discussed.",2012.13222v1
+2021-01-04,Absorption of Microwaves by Random-Anisotropy Magnets,"Microscopic model of the interaction of spins with a microwave field in a
+random-anisotropy magnet has been developed. Numerical results show that
+microwave absorption occurs in a broad range of frequencies due to the
+distribution of Imry-Ma domains on sizes and effective anisotropy. That
+distribution is also responsible for the weak dependence of the absorption on
+the damping. At a fixed frequency of the ac-field the spatial pattern of the
+amplitude of spin oscillations exhibits maxima corresponding to the
+oscillations of resonant magnetic domains. The dependence of the peak
+absorption frequency on the ratio of the magnitude of per-spin random
+anisotropy to the strength of the ferromagnetic exchange agrees with the
+scaling derived from the Imry-Ma argument. The effect noticeably increases in
+low-dimensional systems, suggesting that materials comprised of microscopic
+amorphous leaves and wires can be promising candidates for enhanced microwave
+absorption.",2101.01230v1
+2021-01-05,Tunable Single-Ion Anisotropy in Spin-1 Models Realized with Ultracold Atoms,"Mott insulator plateaus in optical lattices are a versatile platform to study
+spin physics. Using sites occupied by two bosons with an internal degree of
+freedom, we realize a uniaxial single-ion anisotropy term proportional to
+$(S^z)^2$, which plays an important role in stabilizing magnetism for
+low-dimensional magnetic materials. Here we explore non-equilibrium spin
+dynamics and observe a resonant effect in the spin anisotropy as a function of
+lattice depth when exchange coupling and on-site anisotropy are similar. Our
+results are supported by many-body numerical simulations and are captured by
+the analytical solution of a two-site model.",2101.01316v1
+2021-01-07,Optically Facet-Resolved Reaction Anisotropy in Two-Dimensional Transition Metal Dichalcogenides,"Quantifying anisotropy in the chemical reactions of mesoscopic crystals has
+mostly resorted on the combination of electron microscopy and diffraction. In
+this work, we established crystal-facet-resolved kinetic measurements of
+oxidation reactions in 2D transition metal dichalcogenides (TMDs) using optical
+second-harmonic generation spectroscopy and scanning probe microscopy. We show
+the in-plane anisotropy of their bond-breaking reactions is governed by their
+structure and strongly material-dependent among four TMDs. The facet-resolved
+analysis directly revealed that the reactions proceed fastest (slowest) for
+chalcogen (metal)-terminated zigzag edges with armchair edges in the middle.
+The degree of the anisotropy inducing trigonal oxidation patterns was much
+higher in MoS2 and MoSe2 than WS2 and WSe2. Kinetic Wulff construction based on
+edge-specific reaction rates verified the material-dependent mesoscopic
+reaction patterns. We also show that the reactions are initiated at
+substrate-mediated defects located on the bottom and top surfaces of 2D TMDs.",2101.02376v2
+2021-01-13,Self-organization in the one-dimensional Landau-Lifshitz-Gilbert-Slonczewski equation with non-uniform anisotropy fields,"In magnetic films driven by spin-polarized currents, the
+perpendicular-to-plane anisotropy is equivalent to breaking the time
+translation symmetry, i.e., to a parametric pumping. In this work, we
+numerically study those current-driven magnets via the
+Landau-Lifshitz-Gilbert-Slonczewski equation in one spatial dimension. We
+consider a space-dependent anisotropy field in the parametric-like regime. The
+anisotropy profile is antisymmetric to the middle point of the system. We find
+several dissipative states and dynamical behavior and focus on localized
+patterns that undergo oscillatory and phase instabilities. Using numerical
+simulations, we characterize the localized states' bifurcations and present the
+corresponding diagram of phases.",2101.05263v1
+2021-01-19,Cosmic Ray transport in mixed magnetic fields and their role on the observed anisotropies,"There is a growing set of observational data demonstrating that cosmic rays
+exhibit small-scale anisotropies (5-30 deg) with amplitude deviations lying
+between 0.01-0.1 percent that of the average cosmic ray flux. A broad range of
+models have been proposed to explain these anisotropies ranging from
+finite-scale magnetic field structures to dark matter annihilation. The
+standard diffusion transport methods used in cosmic ray propagation do not
+capture the transport physics in a medium with finite-scale or coherent
+magnetic field structures. Here, we present a Monte Carlo transport method,
+applying it to a series of finite-scale magnetic field structures to determine
+the requirements of such fields in explaining the observed cosmic
+ray,small-scale anisotropies.",2101.07759v1
+2021-02-08,Nanoscale decoupling of electronic nematicity and structural anisotropy in FeSe thin films,"In a material prone to a nematic instability, anisotropic strain in principle
+provides a preferred symmetry-breaking direction for the electronic nematic
+state to follow. This is consistent with experimental observations, where
+electronic nematicity and structural anisotropy typically appear hand-in-hand.
+In this work, we discover that electronic nematicity can be locally decoupled
+from the underlying structural anisotropy in strain-engineered iron-selenide
+(FeSe) thin films. We use heteroepitaxial molecular beam epitaxy to grow FeSe
+with a nanoscale network of modulations that give rise to spatially varying
+strain. We map local anisotropic strain by analyzing scanning tunneling
+microscopy topographs, and visualize electronic nematic domains from
+concomitant spectroscopic maps. While the domains form so that the energy of
+nemato-elastic coupling is minimized, we observe distinct regions where
+electronic nematic ordering fails to flip direction, even though the underlying
+structural anisotropy is locally reversed. The findings point towards a
+nanometer-scale stiffness of the nematic order parameter.",2102.04381v1
+2021-02-14,Heavy quark transport in an anisotropic hot QCD medium: Collisional and Radiative processes,"The impact of momentum anisotropy on the heavy quark transport coefficients
+due to collisional and radiative processes in the QCD medium has been studied
+within the ambit of kinetic theory. Anisotropic aspects (momentum) are
+incorporated into the heavy quark dynamics through the non-equilibrium momentum
+distribution function of quarks, antiquarks, and gluons. These non-equilibrium
+distribution functions that encode the physics of momentum anisotropy and
+turbulent chromo-fields have been obtained by solving the ensemble-averaged
+diffusive Vlasov-Boltzmann equation. The momentum dependence of heavy quark
+transport coefficients in the medium is seen to be sensitive to the strength of
+the anisotropy for both collisional and radiative processes. In addition, the
+collisional and radiative energy loss of the heavy quark in the anisotropic hot
+QCD medium have been analyzed. The effects of anisotropy on the drag and
+diffusion coefficients are observed to have a visible impact on the nuclear
+suppression factor both at the RHIC and LHC.",2102.07082v2
+2021-03-07,"Magnetic anisotropy and exchange interactions of two-dimensional FePS$_3$, NiPS$_3$ and MnPS$_3$ from first principles calculations","The van der Waals bonded transition metal phosphorous trichalcogenides
+FePS$_3$, NiPS$_3$ and MnPS$_3$ have recently attracted renewed attention due
+to the possibility of exfoliating them into their monolayers. Although the
+three compounds have similar electronic structure, the magnetic structure
+differs due to subtle differences in exchange and magnetic anisotropy and the
+materials thus comprise a unique playground for studying different aspects of
+magnetism in 2D. Here we calculate the exchange and anisotropy parameters of
+the three materials from first principles paying special attention to the
+choice of Hubbard parameter U. We find a strong dependence of the choice of U
+and show that the calculated N\'eel temperature of FePS$_3$ varies by an order
+of magnitude over commonly applied values of U for the Fe $d$-orbitals. The
+results are compared with parameters fitted to experimental spin-wave spectra
+of the bulk materials and we find excellent agreement between the exchange
+constants when a proper value of U is chosen. However, the anisotropy
+parameters are severely underestimated by DFT and we discuss possible origins
+of this discrepancy.",2103.04474v1
+2021-03-24,Quantifying the anisotropic density structure of the Central Molecular Zone -- a 2D correlation function approach,"The Central Molecular Zone (CMZ) is a ring-like structure sitting at the
+center of the Milky Way. Using the 870 $\mu$m continuum map from the APEX
+Telescope Large Area Survey of the Galaxy (ATLASGAL), we study the anisotropy
+of the density structure of the gas in the Central Molecular Zone (CMZ) using
+the 2D correlation function. To quantify the spatial anisotropy, we define the
+critical angle $\theta_{\rm half}$, as well as the anisotropy parameter
+$A\equiv \frac{\pi}{4\theta_{\rm half}}-1$. We find that the density structure
+is strongly anisotropic at the large scale (~ 100 pc), and the degree of
+spatial anisotropy decreases with the decreasing scale. At the scale of ~ 10
+pc, the structure is still mildly anisotropic. In our analyses, we provide a
+quantitative description of the anisotropic density structure of gas in the
+CMZ, and the formalism can be applied to different regions to study their
+differences.",2103.13048v2
+2021-04-19,Anisotropic quantum Hall states in the presence of interactions with fourfold rotational symmetry,"We study the effects of anisotropic interactions in the quantum Hall effect
+in the presence of a fourfold discrete rotational ($C_4$) symmetry. Employing
+the density matrix renormalization group technique on an infinite cylinder
+geometry (iDMRG), we calculate the anisotropy response of the Laughlin state at
+$\nu=1/3$ and the composite-Fermi liquid (CFL) state at $\nu=1/2$. We find that
+the anisotropy transferred from the interaction potential to the $\nu=1/3$
+state is stronger when compared to the complementary case of an anisotropic
+band. Further, the strength of anisotropy reduces as the interaction is made
+shorter ranged. Quite surprisingly, at $\nu=1/2$, we find that the deformation
+in the CF Fermi-surface changes sign as the interaction range is reduced. Our
+results imply that the short-distance and long-distance parts of the
+interaction potential have opposite effects on the CFL state in the presence of
+$C_4$-symmetric anisotropy.",2104.09670v2
+2021-04-26,Switching between Magnetic Bloch and Néel Domain Walls with Anisotropy Modulations,"It has been shown previously that the presence of a Dzyaloshinskii-Moriya
+interaction in perpendicularly magnetized thin films stabilizes N\'eel type
+domain walls. We demonstrate, using micromagnetic simulations and analytical
+modeling, that the presence of a uniaxial in-plane magnetic anisotropy can also
+lead to the formation of N\'eel walls in the absence of a Dzyaloshinskii-Moriya
+interaction. It is possible to abruptly switch between Bloch and N\'eel walls
+via a small modulation of both the in-plane, but also the perpendicular
+magnetic anisotropy. This opens up a route towards electric field control of
+the domain wall type with small applied voltages through electric field
+controlled anisotropies.",2104.12400v2
+2021-05-07,CMB Mode Coupling with Isotropic Polarization Rotation,"We provide a new analysis technique to measure the effect of the isotropic
+polarization rotation, induced by e.g. the isotropic cosmic birefringence from
+axion-like particles and a miscalibration of CMB polarization angle, via mode
+coupling in the cosmic microwave background (CMB). Several secondary effects
+such as gravitational lensing and CMB optical-depth anisotropies lead to mode
+coupling in observed CMB anisotropies, i.e., non-zero off-diagonal elements in
+the observed CMB covariance. To derive the mode coupling, however, we usually
+assume no parity violation in the observed CMB anisotropies. We first derive a
+new contribution to the CMB mode coupling arising from parity violation in
+observed CMB. Since the isotropic polarization rotation leads to parity
+violation in the observed CMB anisotropies, we then discuss the use of the new
+mode coupling for constraining the isotropic polarization angle. We find that
+constraints on the isotropic polarization angle by measuring the new
+mode-coupling contribution are comparable to that using the $EB$ cross-power
+spectrum in future high-sensitivity polarization experiments such as CMB-S4 and
+LiteBIRD. Thus, this technique can be used to cross-check results obtained by
+the use of the $EB$ cross-power spectrum.",2105.03367v1
+2021-05-08,Breaking of Ginzburg-Landau description in the temperature dependence of the anisotropy in the nematic superconductor,"Nematic superconductors are characterized by an apparent crystal symmetry
+breaking that results in the anisotropy of the in-plane upper critical magnetic
+field $H_{c2}$. The symmetry breaking is usually attributed to the strain of
+the crystal lattice. The nature and the value of the strain are debatable. We
+perform systematic measurements of the $H_{c2}$ anisotropy in the high-quality
+Sr$_x$Bi$_2$Se$_3$ single crystals in the temperature range 1.8~K$<T<T_c\approx
+2.7$~K using temperature stabilization with an accuracy of 0.0001 K. We observe
+that in all tested samples the anisotropy is weakly temperature dependent when
+$T<0.8\,T_c$ and smoothly decreases at higher temperatures without any sign of
+singularity when $T\rightarrow T_c$. Such a behavior {is in a drastic
+contradiction with the prediction of} the Ginzburg-Landau theory for the
+nematic superconductors. We discuss possible reasons for this discrepancy.",2105.03696v2
+2021-05-10,Role of Majorana fermions in spin transport of anisotropic Kitaev model,"We study a quantum spin Kitaev model with zigzag edges to clarify the effects
+of anisotropy in the exchange couplings on the spin propagation. We simulate
+the spin and Majorana dynamics triggered by a magnetic pulse, using the
+real-space time-dependent Majorana mean-field theory. When the anisotropy is
+small, the dispersion of the itinerant Majorana fermions remains gapless, where
+the velocity of the spin propagation matches the group velocity of the
+itinerant Majorana fermions at the nodal points. On the other hand, in the
+gapped system with a large anisotropy, the spin propagation is strongly
+suppressed although its nature depends on the shape of the pulse. The spin
+transport in the junction system described by the Kitaev models with distinct
+anisotropies is also dressed.",2105.04094v1
+2021-05-10,Is there Anisotropy in Structural Bias?,"Structural Bias (SB) is an important type of algorithmic deficiency within
+iterative optimisation heuristics. However, methods for detecting structural
+bias have not yet fully matured, and recent studies have uncovered many
+interesting questions. One of these is the question of how structural bias can
+be related to anisotropy. Intuitively, an algorithm that is not isotropic would
+be considered structurally biased. However, there have been cases where
+algorithms appear to only show SB in some dimensions. As such, we investigate
+whether these algorithms actually exhibit anisotropy, and how this impacts the
+detection of SB. We find that anisotropy is very rare, and even in cases where
+it is present, there are clear tests for SB which do not rely on any
+assumptions of isotropy, so we can safely expand the suite of SB tests to
+encompass these kinds of deficiencies not found by the original tests.
+  We propose several additional testing procedures for SB detection and aim to
+motivate further research into the creation of a robust portfolio of tests.
+This is crucial since no single test will be able to work effectively with all
+types of SB we identify.",2105.04480v1
+2021-05-18,Bumblebee field as a source of cosmological anisotropies,"In this work, a bumblebee field is adopted in order to generate cosmological
+anisotropies. For that purpose, we assume a Bianchi I cosmology, as the
+background geometry, and a bumblebee field coupled to it. Bumblebee models are
+examples of a mechanism for the Lorentz symmetry violation by assuming a
+nonzero vacuum expectation value for the bumblebee field. When coupled to the
+Bianchi I geometry, which is not in agreement with a cosmological principle,
+the bumblebee field plays the role of a source of anisotropies and produces a
+preferred axis. Thus, a fraction of the cosmic anisotropies would come from the
+Lorentz symmetry violation. In the last part of the article, we try to assume
+an upper bound on the bumblebee field using the quadrupole and octopole moments
+of the cosmic microwave background radiation.",2105.08659v3
+2021-05-21,Elastic anisotropy of nematic liquid crystals in the two-dimensional Landau-de Gennes model,"We study the effects of elastic anisotropy on the Landau-de Gennes critical
+points for nematic liquid crystals, in a square domain. The elastic anisotropy
+is captured by a parameter, $L_2$, and the critical points are described by
+three degrees of freedom. We analytically construct a symmetric critical point
+for all admissible values of $L_2$, which is necessarily globally stable for
+small domains i.e., when the square edge length, $\lambda$, is small enough. We
+perform asymptotic analyses and numerical studies to discover at least $5$
+classes of these symmetric critical points - the $WORS$, $Ring^{\pm}$,
+$Constant$ and $pWORS$ solutions, of which the $WORS$, $Ring^+$ and $Constant$
+solutions can be stable. Furthermore, we demonstrate that the novel $Constant$
+solution is energetically preferable for large $\lambda$ and large $L_2$, and
+prove associated stability results that corroborate the stabilising effects of
+$L_2$ for reduced Landau-de Gennes critical points. We complement our analysis
+with numerically computed bifurcation diagrams for different values of $L_2$,
+which illustrate the interplay of elastic anisotropy and geometry for nematic
+solution landscapes, at low temperatures.",2105.10253v1
+2021-05-26,Quarkonium dissociation properties of hot QCD medium at momentum-anisotropy in the N-dimensional space using Quasi-particle Debye mass with finite baryonic chemical potential,"The analytical exact iteration method (AEIM) have been used to calculate the
+N-dimensional radial schrodinger equation with the real part of complex-valued
+potential and it is generalized to the finite value of anisotropy ({\xi}),
+temperature and baryonic chemical potential. In N-dimensional space the energy
+eigen values have been calculated for any states (n,l). The present results
+have been used to study the properties of quarkonium states (i.e, the binding
+energy and mass spectra in the N-dimensional space). The influences of
+anisotropy ({\xi}) on the dissociation temperature(TD) has been also calculated
+for the ground state of quarkonia at N=0 and \mu = 300MeV . The anisotropy in
+oblate case, thus obtained, makes the dissociation temperature(TD) lower as
+compared to the isotropic case . We also seen that Leading order Debye mass is
+greater than that of Quasi-particle Debye mass after introducing the baryonic
+chemical potential.",2105.12346v3
+2021-05-28,Anisotropic Magnon Spin Transport in Ultra-thin Spinel Ferrite Thin Films -- Evidence for Anisotropy in Exchange Stiffness,"We report measurements of magnon spin transport in a spinel ferrite,
+magnesium aluminum ferrite $\mathrm{MgAl_{0.5}Fe_{1.5}O_4}$ (MAFO), which has a
+substantial in-plane four-fold magnetic anisotropy. We observe spin diffusion
+lengths $> 0.8$ $\mathrm{\mu m}$ at room temperature in 6 nm films, with spin
+diffusion length 30% longer along the easy axes compared to the hard axes. The
+sign of this difference is opposite to the effects just of anisotropy in the
+magnetic energy for a uniform magnetic state. We suggest instead that
+accounting for anisotropy in exchange stiffness is necessary to explain these
+results.",2105.13943v1
+2021-06-07,Influence of microstructural and crystallographic inhomogeneity on tensile anisotropy in thick-section Al-Li-Cu-Mg plates,"Thick-section plates made from a recently developed Al-Cu-Mg-Li alloy have
+been evaluated to understand the influence of microstructure on the anisotropy
+of tensile strengths after natural and artificial ageing treatment.
+Pancake-shaped grains with a coarse substructure and strong crystallographic
+texture with a beta-fibre orientation at the mid-thickness position are
+observed. In addition, an inhomogeneous distribution of T1 precipitates through
+the plate thickness has been revealed with the volume fraction of intragranular
+precipitates ~ 40% higher at the plate centre than the thickness position.
+Altogether these microstructural features contribute to the in-plane anisotropy
+of tensile strengths that is ~ 5% higher at the mid-thickness position than the
+1/4 thickness position. The variation of ageing-induced T1 precipitates through
+the plate thickness further contributes to the through-thickness anisotropy
+that is ~ 3% higher in T8 temper as compared to T3 temper.",2106.03644v1
+2021-07-07,Shape anisotropy enhances the elasticity of colloidal gels through mechanisms that act multiplicatively,"The physical gelation of colloids produces elastic structures that are
+commonly used to stabilize complex fluids in multiple industries. However, the
+ability to control the level of elastic modulus of these materials is limited
+by the universality of the arrested spinodal decomposition mechanism that
+governs their formation. We demonstrate that manipulating particle shape can
+yield very large shifts in gel elasticity relative to this universal behavior,
+and that these changes are generated by a set of independent mechanisms that
+act multiplicatively. Modeling demonstrates that this efficient generation of
+elasticity is the consequence of the combined effects of shape anisotropy on
+the hierarchical fractal microstructure of the gel network, the anisotropy of
+the attractive interparticle pair potentials, and the volumetric compactness of
+the fractal cluster. The findings show how and why particle anisotropy can be
+exploited to generate elasticity at ultra-low colloidal volume fractions in
+this important class of soft matter.",2107.03422v1
+2021-07-08,Nontrivial temperature dependence of magnetic anisotropy in multiferroics Ba$_2$MnGe$_2$O$_7$,"We measured the temperature dependences of the static magnetization and the
+spin excitation in a square-lattice multiferroics Ba$_2$MnGe$_2$O$_7$. An
+anisotropy gap of the observed low energy mode is scaled by electric
+polarization rather than a power of sublattice moment. Spin nematic interaction
+in effective spin Hamiltonian, which is equivalent to interaction of electric
+polarization, is responsible for the easy-axis anisotropy. The nontrivial
+behavior of the anisotropy gap can be rationalized as change of the hybridized
+$d$-$p$ orbital with temperature, leading to the temperature dependence of the
+spin nematic interaction.",2107.03928v1
+2021-08-20,Probing anisotropy in epitaxial Fe/Pt bilayers by spin-orbit torque ferromagnetic resonance,"We report the generation and detection of spin-orbit torque ferromagnetic
+resonance (STFMR) in micropatterned epitaxial Fe/Pt bilayers grown by molecular
+beam epitaxy. The magnetic field dependent measurements at an in-plane magnetic
+field angle of 45 degrees with respect to the microwave-current direction
+reveal the presence of two distinct voltage peaks indicative of a strong
+magnetic anisotropy. We show that STFMR can be employed to probe the underlying
+magnetic properties including the anisotropies in the Fe layer. We compare our
+STFMR results with broadband ferromagnetic resonance spectroscopy of the
+unpatterned bilayer thin films. The experimental STFMR measurements are
+interpreted using an analytical formalism and further confirmed using
+micromagnetic modeling, which shed light on the field-dependent magnetization
+alignment in the microstructures responsible for the STFMR rectification. Our
+results demonstrate a simple and efficient method for determining magnetic
+anisotropies in microstructures by means of rf spectroscopy.",2108.09132v1
+2021-08-24,Out-of-plane magnetic anisotropy in bulk ilmenite $\text{CoTiO}_3$,"Structural, electronic and magnetic properties of bulk ilmenite CoTiO$_3$ are
+analyzed in the framework of density functional theory (DFT), using the
+generalized gradient approximation (GGA) and Hubbard-corrected approaches. We
+find that the G-type antiferromagnetic (G-AFM) structure, which consists of
+antiferromagnetically coupled ferromagnetic $ab$ planes, is the ground-state of
+the system, in agreement with experiments. Furthermore, cobalt titanates
+present two critical temperatures related to the breaking of the inter- and
+intra-layer magnetic ordering. This would result in the individual planes
+remaining ferromagnetic even at temperatures above the N\'{e}el temperature.
+When spin-orbit coupling is included in our calculations, we find an
+out-of-plane magnetic anisotropy, which can be converted to an in-plane
+anisotropy with a small doping of electrons corresponding to about 2.5% Ti
+substitution for Co, consistent with experimental expectations. We thus present
+a disorder-dependent study of the magnetic anisotropy in bulk $\text{CoTiO}_3$,
+which will determine its magnon properties, including topological aspects.",2108.10847v2
+2021-09-06,On optimal cloaking-by-mapping transformations,"A central ingredient of cloaking-by-mapping is the diffeomorphisn which
+transforms an annulus with a small hole into an annulus with a finite size
+hole, while being the identity on the outer boundary of the annulus. The
+resulting meta-material is anisotropic, which makes it difficult to
+manufacture. The problem of minimizing anisotropy among radial transformations
+has been studied in [4]. In this work, as in [4], we formulate the problem of
+minimizing anisotropy as an energy minimization problem. Our main goal is to
+provide strong evidence for the conjecture that for cloaks with circular
+boundaries, non-radial transformations do not lead to lower degree of
+anisotropy. In the final section, we consider cloaks with non-circular
+boundaries and show that in this case, non-radial cloaks may be advantageous,
+when it comes to minimizing anisotropy.",2109.02397v1
+2021-09-21,Effect of uniaxial single-ion anisotropy on a stability of intermediate magnetization plateaus of a spin-1 Heisenberg diamond cluster,"Ground-state phase diagrams and magnetization curves of a spin-1 Heisenberg
+diamond cluster with two different coupling constants and uniaxial single-ion
+anisotropy are investigated in a presence of the external magnetic field with
+the help of exact diagonalization methods. It is shown that the spin-1
+Heisenberg diamond cluster exhibits several remarkable quantum ground states,
+which are manifested in zero- and low-temperature magnetization curves as
+intermediate plateaus at one-quarter, one-half and three-quarters of the
+saturation magnetization. It is found that the width of the fractional
+magnetization plateaus depends basically on a relative strength of the coupling
+constants as well as uniaxial single-ion anisotropy, which may substantially
+shrink or even cause full breakdown of some intermediate magnetization
+plateaus. It is evidenced that a relatively weak uniaxial single-ion anisotropy
+of the easy-axis type considerably improves a theoretical fit of
+low-temperature magnetization curves of the tetranuclear nickel complex
+[Ni4(CO3)2(aetpy)8](ClO4)4 in a low-field region without spoiling the previous
+fit based on the fully isotropic Heisenberg model in a high-field region.",2109.10030v1
+2021-10-25,Emergent anisotropy in the Fulde-Ferrell-Larkin-Ovchinnikov state,"Exotic superconductivity is formed by unconventional electron pairing and
+exhibits various unique properties that cannot be explained by the basic
+theory. The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state is known as an exotic
+superconducting state in that the electron pairs have a finite center-of-mass
+momentum leading to a spatially modulated pattern of superconductivity. The
+spatial modulation endows the FFLO state with emergent anisotropy. However, the
+anisotropy has never been experimentally verified despite numerous efforts over
+the years. Here, we report detection of anisotropic acoustic responses
+depending on the sound propagation direction appearing above the Pauli limit.
+This anisotropy reveals that the two-dimensional FFLO state has a
+center-of-mass momentum parallel to the nesting vector on the Fermi surface.
+The present findings will facilitate our understanding of not only
+superconductivity in solids but also exotic pairings of various particles.",2110.12774v2
+2021-10-29,"Stripe order, impurities, and symmetry breaking in a diluted frustrated magnet","We investigate the behavior of the frustrated $J_1$-$J_2$ Ising model on a
+square lattice under the influence of random dilution and spatial anisotropies.
+Spinless impurities generate a random-field type disorder for the spin-density
+wave (stripe) order parameter. These random fields destroy the long-range
+stripe order in the case of spatially isotropic interactions. Combining
+symmetry arguments, percolation theory and large-scale Monte Carlo simulations,
+we demonstrate that arbitrarily weak spatial interaction anisotropies restore
+the stripe phase. More specifically, the transition temperature $T_c$ into the
+stripe phase depends on the interaction anisotropy $\Delta J$ via $T_c \sim
+1/|\ln (\Delta J)|$ for small $\Delta J$. This logarithmic dependence implies
+that very weak anisotropies are sufficient to restore the transition
+temperature to values comparable to that of the undiluted system. We analyze
+the critical behavior of the emerging transition and find it to belong to the
+disordered two-dimensional Ising universality class, which features the clean
+Ising critical exponents and universal logarithmic corrections. We also discuss
+the generality of our results and their consequences for experiments.",2111.00101v2
+2021-11-15,On the phase diagram of a three-dimensional dipolar model,"The magnetic phase diagram at zero external field of an ensemble of dipoles
+with uniaxial anisotropy on a FCC lattice has been investigated from tempered
+Monte Carlo simulations. The uniaxial anisotropy is characterized by a random
+distribution of easy axes and its magnitude $\lambda_u$ is the driving force of
+disorder and consequently frustration. The phase diagram, separating the
+paramagnetic, ferromagnetic and spin-glass regions, was thus considered in the
+temperature, $\lambda_u$ plane. Here we interpret this phase diagram in terms
+of the more convenient variables namely the bare dipolar interaction and
+anisotropy energies $\epsilon_d$ and $\epsilon_u$ on the one hand and the
+volume fraction $\Phi$ on the other hand and compare the result with that
+corresponding to the random distribution of particles in the absence of
+anisotropy. We also display the nature of the ordered phase reached at low
+temperature by the ensemble of dipoles on the FCC lattice in terms of both the
+dipolar coupling and the texturation of the easy axes distribution when the
+latter is no more random. This system is aimed at modeling the magnetic phase
+diagram of supracrystals of magnetic nanoparticles.",2111.07709v1
+2022-01-03,Susceptibility of Polar Flocks to Spatial Anisotropy,"We consider the effect of spatial anisotropy on polar flocks by investigating
+active $q$-state clock models in two dimensions. In contrast to what happens in
+equilibrium, we find that, in the large-size limit, any amount of anisotropy
+changes drastically the phenomenology of the rotationally-invariant case,
+destroying long-range correlations, pinning the direction of global order, and
+transforming the traveling bands of the coexistence phase into a single moving
+domain. All this happens beyond a lengthscale that diverges in the $q\to\infty$
+limit. A phenomenology akin to that of the Vicsek model can thus be observed in
+a finite system for large enough values of $q$. We provide a scaling argument
+which rationalizes why anisotropy has so different effects in the passive and
+active cases.",2201.00704v2
+2022-01-11,Non-resonant relaxation of anisotropic globular clusters,"Globular clusters are dense stellar systems whose core slowly contracts under
+the effect of self-gravity. The rate of this process was recently found to be
+directly linked to the initial amount of velocity anisotropy: tangentially
+anisotropic clusters contract faster than radially anisotropic ones.
+Furthermore, initially anisotropic clusters are found to generically tend
+towards more isotropic distributions during the onset of contraction.
+Chandrasekhar's ""non-resonant"" (NR) theory of diffusion describes this
+relaxation as being driven by a sequence of local two-body deflections along
+each star's orbit. We explicitly tailor this NR prediction to anisotropic
+clusters, and compare it with $N$-body realisations of Plummer spheres with
+varying degrees of anisotropy. The NR theory is shown to recover remarkably
+well the detailed shape of the orbital diffusion and the associated initial
+isotropisation, up to a global multiplicative prefactor which increases with
+anisotropy. Strikingly, a simple effective isotropic prescription provides
+almost as good a fit, as long as the cluster's anisotropy is not too strong.
+For these more extreme clusters, accounting for long-range resonant relaxation
+may be necessary to capture these clusters' long-term evolution.",2201.03985v1
+2022-02-17,A Three-component Model for Cosmic-ray Spectrum and Dipole Anisotropy,"Using a three-component, multi-scale diffusion model, we show that the
+cosmic-ray (CR) proton and helium spectra and the dipole anisotropy can be
+explained with reasonable parameters. The model includes a nearby source
+associated with the supernova remnant (SNR) that gave rise to the Geminga
+pulsar, a source at the Galactic center, and a component associated with the
+Galactic disk. The CR flux below TeV is dominated by the disk component. The
+center source with a continuous injection of CRs starting about 18 Myr ago is
+needed to explain the anisotropy above 100 TeV. With the assumption of
+universal CR spectra injected by all SNRs, the nearby source can produce a TeV
+spectral bump observed at Earth via slow diffusion across the interstellar
+magnetic field, which needs to have an angle $ \theta \approx 5^{\circ} $
+between the field line and the line of sight toward the source, and have weak
+magnetic turbulence with the Alfv\'{e}n Mach number $ M_{\text{A}}\approx 0.1
+$. Considering the modulation of the Galactic-scale anisotropy by this magnetic
+field, in a quasi-local approach the field may be directed at a right ascension
+about $ -90^{\circ} $ and a declination about $ -7.4^{\circ} $ in the
+equatorial coordinate system.",2202.08491v1
+2022-04-15,Dipole Anisotropy in Gravitational Wave Source Distribution,"Our local motion with respect to the cosmic frame of rest is believed to be
+dominantly responsible for the observed dipole anisotropy in the Cosmic
+Microwave Background Radiation (CMBR). We study the effect of this motion on
+the sky distribution of gravitational wave (GW) sources. We determine the
+resulting dipole anisotropy in GW source number counts, mass weighted number
+counts, which we refer to as mass intensity, and mean mass per source. The mass
+M dependence of the number density n(M) distribution of BBH is taken directly
+from the data. We also test the anisotropy in the observable mean mass per
+source along the direction of the CMB dipole. The current data sample is
+relatively small and consistent with isotropy. The number of sources required
+for this test is likely to become available in the near future.",2204.07472v3
+2022-04-16,On the anisotropy theorem of Papadakis and Petrotou,"We study the anisotropy theorem for Stanley-Reisner rings of simplicial
+homology spheres in characteristic 2 by Papadakis and Petrotou. This theorem
+implies the Hard Lefschetz theorem as well as McMullen's g-conjecture for such
+spheres. Our first result is an explicit description of the quadratic form. We
+use this description to prove a conjecture stated by Papadakis and Petrotou.
+All anisotropy theorems for homology spheres and pseudo-manifolds in
+characteristic 2 follow from this conjecture. Using a specialization argument,
+we prove anisotropy for certain homology spheres over the field $\mathbb{Q}$.
+These results provide another self-contained proof of the g-conjecture for
+homology spheres in characteristic 2.",2204.07758v3
+2022-05-11,Enhancing gravitational wave anisotropies with peaked scalar sources,"Gravitational wave (GW) backgrounds of cosmological origin are expected to be
+nearly isotropic, with small anisotropies resembling those of the cosmic
+microwave background. We analyse the case of a scalar-induced GW background and
+clarify in the process the relation between two different approaches to
+calculating GW anisotropies. We focus on GW scenarios sourced by a
+significantly peaked scalar spectrum, which are frequently considered in the
+context of primordial black holes production. We show that the resulting GW
+anisotropies are characterised by a distinct frequency dependence. We explore
+the observational consequences concentrating on a GW background enhanced in the
+frequency band of space-based GW detectors. We study the detectability of the
+signal through both cross-correlations among different space-based GW
+detectors, and among GW and CMB experiments.",2205.05644v2
+2022-05-22,Rashba spin-orbit interaction induced modulation of magnetic anisotropy,"In past few decades, Rashba spin-orbit coupling (SOC) has been successfully
+employed for the emergence of exotic phenomena at the quantum oxide interfaces.
+In these systems, the combined effect of charge transfer, broken symmetries and
+SOC yields intriguing interfacial magnetism and transport properties. Here, we
+provide an insight to control and tune interfacial phenomena in CaMnO3/CaIrO3
+based 3d-5d oxide heterostructures by the charge transfer driven Rashba SOC.
+Anomalous Hall effect in these canted antiferromagnetic heterostructures
+originates from the intrinsic contribution associated with the topology of the
+electronic band structure and it is mostly confined to the interface. Rashba
+SOC reconstructs the Berry curvature and enhances the anomalous Hall
+conductivity by two orders of magnitude. From the anisotropy magnetoresistance
+measurements we demonstrate that Rashba SOC is instrumental in tailoring
+magnetic anisotropy where magnetization easy-axis rotates from the out-of-plane
+direction to the in-plane direction. The ability to tune Rashba SOC and
+resulting competing magnetic anisotropy provides a route to manipulate
+electronic band structure for the origin of non-trivial spin texture useful for
+spin-orbitronics applications.",2205.10859v1
+2022-06-01,Spectral Recognition of Magnetic Nanoparticles with Artificial Neural Networks,"Ferromagnetic resonance (FMR) spectroscopy is a powerful method for
+quantifying internal magnetic anisotropy fields in nanoparticles, which is
+important in a wide range of biomedical and storage applications. The
+interpretation of FMR spectra, however, can only be achieved with the use of an
+appropriate model, and no inverse methods are available to extract internal
+fields from FMR spectra. Here, we present the use of artificial neural networks
+for spectral recognition, i.e., to identify the internal magnetic anisotropy
+field from the FMR spectrum. We trained two different types of networks, a
+convolutional neural network and a multi-layer perceptron, by feeding the
+networks pre-computed FMR spectra labeled with the corresponding anisotropy
+fields. Testing of the trained networks with unseen spectra showed that they
+successfully predict the correct anisotropy fields and, surprisingly, the
+networks performed well for data that was beyond their training range. These
+results show the promise of using artificial neural networks for accelerated
+high-throughput analysis of magnetic materials and nanostructures; for example
+they could serve in automatizing and optimizing exploration missions where
+nanomagnetic signals are often used as proxies.",2206.00166v1
+2022-06-05,Evidence of Magnon-Mediated Orbital Magnetism in a Quasi-2D Topological Magnon Insulator,"We explore spin dynamics in Cu(1,3-bdc), a quasi-2D topological magnon
+insulator. The results show that the thermal evolution of Land\'e $g$-factor
+($g$) is anisotropic: $g_\textrm{in-plane}$ reduces while
+$g_\textrm{out-plane}$ increases with increasing temperature $T$. Moreover, the
+anisotropy of the $g$-factor ($\Delta g$) and the anisotropy of saturation
+magnetization ($\Delta M_\textrm{s}$) are correlated below 4 K, but they
+diverge above 4 K. We show that the electronic orbital moment contributes to
+the $g$ anisotropy at lower $T$, while the topological orbital moment induced
+by thermally excited spin chirality dictates the $g$ anisotropy at higher $T$.
+Our work suggests an interplay among topology, spin chirality, and orbital
+magnetism in Cu(1,3-bdc).",2206.02191v1
+2022-06-30,Ce and Dy substitutions in Nd$_{2}$Fe$_{14}$B: site-specific magnetic anisotropy from first-principles,"A first-principles approach combining density functional and dynamical
+mean-field theories in conjunction with a quasi-atomic approximation for the
+strongly localized 4$f$ shell is applied to Nd$_{2}$Fe$_{14}$B-based hard
+magnets in order to evaluate crystal-field and exchange-field parameters at
+rare-earth sites and their corresponding single-ion contribution to the
+magnetic anisotropy. In pure Nd$_2$Fe$_{14}$B, our calculations reproduce the
+easy-cone to easy axis transition; theoretical magnetization curves agree
+quantitatively with experiment. Our study reveals that the rare-earth
+single-ion anisotropy in the ""2-14-1"" structure is strongly site-dependent,
+with the $g$ rare-earth site exhibiting a larger value. In particular, we
+predict that increased $f$ and $g$-site occupancy of $R=$ Ce and Dy,
+respectively, leads to an increase of the magnetic anisotropy of the
+corresponding (Nd,$R$)$_{2}$Fe$_{14}$B substituted compounds.",2206.15093v1
+2022-08-02,Novel setup for detecting short-range anisotropic corrections to gravity,"In this paper we argue that, even though there are strong theoretical and
+empirical reasons to expect a violation of spatial isotropy at short distances,
+contemporary setups for probing gravitational interactions at short distances
+have not been configured to measure such spatial anisotropies. We propose a
+simple modification to the state-of-the-art torsion pendulum design and
+numerically demonstrate that it suppresses signals due to the large
+spatially-isotropic component of the gravitational force while maintaining a
+high sensitivity to short-range spatial anisotropies. We incorporate anisotropy
+using both Yukawa-type and power-law-type short-distance corrections to
+gravity. The proposed differential torsion pendulum is shown to be capable of
+making sensitive measurements of small gravitational anisotropies and the
+resulting anisotropic torques are largely independent of the details of the
+underlying short-distance modification to gravity. Thus, if there is an
+anisotropic modification to gravity, from any theory, in any form of the
+modified potential, the proposed setup provides a practical means of detecting
+it.",2208.01645v3
+2022-08-11,Nearby active galactic nuclei and starburst galaxies as sources of the measured UHECRs anisotropy signal,"The Pierre Auger and the Telescope Array observatories have measured
+independent and statistical significant anisotropy in the arrival direction of
+ultra-high-energy cosmic rays (UHECR). Three hotspot regions with relative
+excess of events and a dipole signal have been identified in different regions
+of the sky and energy ranges. In this paper, we investigate the conditions
+under which these anisotropy signal could be generated by nearby (<23 Mpc)
+active galactic nuclei (AGN) and/or starburst galaxies (SBG). We studied a wide
+range of possibilities including injected nuclei (p, He, N, Si, and Fe), three
+UHECR luminosity proxies and three extragalactic magnetic field models. The
+results shows that both local AGN and SBG are needed to describe all the
+anisotropy signal. The contribution of AGN to hotspots and to the generation of
+the dipole is dominant in most cases. SBG is required only to explain the
+hotspot measured by the Telescope Array Observatory.",2208.05849v2
+2022-08-16,Anisotropy of the Optical Properties of Pentacene:Black Phosphorus Interfaces,"Black phosphorus (BP) is a layered material with anisotropic properties. We
+study interfaces formed by a pentacene monolayer adsorbed on monolayer BP, a
+prototypical system for BP surface passivation. We place the pentacene
+monolayer along the zigzag and armchair directions of the BP substrate,
+respectively, to examine the anisotropy of the heterogeneous interfaces. We
+perform first-principles $GW$ plus Bethe-Salpeter equation ($GW$-BSE)
+calculations to determine the quasiparticle and optical properties. To
+quantitatively analyze the anisotropy of the optical properties, we develop a
+general computational scheme to decompose the interface excitons into different
+contributions. We find a distinct charge-transfer exciton formed when the
+monolayer pentacene is placed along the armchair direction, and discuss how the
+anisotropy of each component is modulated by the interface. Our results shine a
+light on the understanding of the BP surface passivation via molecular
+adsorption and provide a benchmark for future experimental and computational
+studies.",2208.07780v1
+2022-08-31,Bose-Einstein condensation in honeycomb dimer magnets and $\rm Yb_2 \rm Si_2 \rm O_7$,"An asymmetric Bose-Einstein condensation (BEC) dome was observed in a recent
+experiment on the quantum dimer magnet $\rm Yb_2Si_2O_7$, which is modeled by a
+""breathing"" honeycomb lattice Heisenberg model with possible anisotropies. We
+report a remarkable agreement between key experimental features and predictions
+from numerical simulations of the magnetic model. Both critical fields, as well
+as critical temperatures of the BEC dome, can be accurately captured, as well
+as the occurrence of two regimes inside the BEC phase. Furthermore, we
+investigate the role of anisotropies in the exchange coupling and the
+$g$-tensor. While we confirm a previous proposal that anisotropy can induce a
+zero temperature phase transition at magnetic fields smaller than the fully
+polarizing field strength, we find that this effect becomes negligible at
+temperatures above the anisotropy scale. Instead, the two regimes inside the
+BEC dome are found to be due to a non-linear magnetization behavior of the
+isotropic breathing honeycomb Heisenberg antiferromagnet. Our analysis is
+performed by combining the density matrix renormalization group (DMRG) method
+with the finite-temperature techniques of minimally entangled typical thermal
+states (METTS) and quantum Monte Carlo (QMC).",2209.00032v1
+2022-09-13,On the response of the Einstein Telescope to Doppler anisotropies,"We study the response function of the Einstein Telescope to kinematic Doppler
+anisotropies, which represent one of the guaranteed properties of the
+stochastic gravitational wave background. If the frequency dependence of the
+stochastic background changes slope within the detector frequency band, the
+Doppler anisotropic contribution to the signal can not be factorized in a part
+depending on frequency, and a part depending on direction. For the first time,
+we study the detector response function to Doppler anisotropies without making
+any factorizable Ansatz. Moreover, we do not assume that kinematic effects are
+small, and we derive general formulas valid for any relative velocity among
+frames. We apply our findings to three well-motivated examples of background
+profiles: power-law, broken power-law, and models with a resonance motivated by
+primordial black hole scenarios. We derive the signal-to-noise ratio associated
+with an optimal estimator for the detection of non-factorizable kinematic
+anisotropies, and we study it for representative examples.",2209.05770v2
+2022-09-29,Effect of temperature anisotropy on the dynamics of geodesic acoustic modes,"In this work, we revisit the linear gyro-kinetic theory of geodesic acoustic
+modes (GAMs) and derive a general dispersion relation for an arbitrary
+equilibrium distribution function of ions. A bi-Maxwellian distribution of ions
+is then used to study the effects of ion temperature anisotropy on GAM
+frequency and growth rate. We find that ion temperature anisotropy yields
+sensible modifications to both the GAM frequency and growth rate as both tend
+to increase with anisotropy and these results are strongly affected by the
+electron to ion temperature ratio.",2209.14874v2
+2022-10-11,Disorder effects on the metastability of classical Heisenberg ferromagnets,"In the present work, we investigate the effects of disorder on the reversal
+time ($\tau$) of classical anisotropic Heisenberg ferromagnets in three
+dimensions by means of Monte Carlo simulations. Starting from the pure system,
+our analysis suggests that $\tau$ increases with increasing anisotropy
+strength. On the other hand, for the case of randomly distributed anisotropy,
+generated from various statistical distributions, a set of results is obtained:
+(i) For both bimodal and uniform distributions the variation of $\tau$ with the
+strength of anisotropy strongly depends on temperature. (ii) At lower
+temperatures, the decrement in $\tau$ with increasing width of the distribution
+is more prominent. (iii) For the case of normally distributed anisotropy, the
+variation of $\tau$ with the width of the distribution is non-monotonic,
+featuring a minimum value that decays exponentially with the temperature.
+Finally, we elaborate on the joint effect of longitudinal ($h_z$) and
+transverse ($h_x$) fields on $\tau$, which appear to obey a scaling behavior of
+the form $\tau h_z^{n} \sim f(h_x)$.",2210.05510v2
+2022-10-14,Higher-order magnetic anisotropy in soft-hard magnetic materials,"We have computationally studied the properties of higher-order magnetic
+anisotropy constants in an L10/A1-FePt coreshell system which is characterized
+by a strong second-order 2-ion Fe-Pt anisotropy component. We show that the
+coreshell structure induces an unexpected fourth-order anisotropy constant K2
+the magnitude of which varies non-monotonically with the core-size ratio R
+reaching a peak at R = 0.50. Furthermore, we find that K2 scales with the
+normalized magnetization by (M/Ms)^2.2 at temperatures below the Curie
+temperature - a remarkable deviation from the established Callen-Callen theory
+which instead predicts a scaling exponent of 10. We construct an analytic model
+which demonstrates K2 arises from the canting of the core and shell
+magnetization, and successfully reproduces and justifies the scaling exponent
+obtained from numerical simulation.",2210.07875v1
+2022-10-25,How can we explain last UHERC anisotropies?,"We consider the recent results on UHECR (Ultra High Energy Cosmic Ray),
+clustering, composition, distribution in the sky, from the energy of several
+EeV with the dipole anisotropy up to the highest ones. We have suggested since
+2008 and we reconfirm here that UHECR at 40 up to 70 EeV are mostly made by
+light and lightest nuclei. The remarkable Virgo absence and the few localized
+nearby extragalactic sources as CenA, NG 253, M82 may be well understood by the
+lightest nuclei fragility and opacity within Mpc distances. We comment also on
+the role of a few galactic UHECR sources at ten EeV that may be partially
+feeding the Auger dipole UHECR anisotropy. The recent anisotropy in the UHECR
+spectral composition of lightest and heavy nuclei, outside and along the
+galactic plane, could also be a first confirmation of our previous claims
+(2012). The interplay of the heavier and most energetic UHECR galactic nuclei
+with the mainly local (Mpcs) extragalactic signals ruled by lightest nuclei,
+seems to fit the main pieces of UHECR puzzle.",2210.14365v1
+2022-10-27,Spectro-spatial evolution of the CMB II: generalised Boltzmann hierarchy,"In this paper, we formulate a generalised photon Boltzmann hierarchy that
+allows us to model the evolution and creation of spectral distortion
+anisotropies in the early Universe. We directly build on our first paper in
+this series, extending the thermalisation Green's function treatment to the
+anisotropic case. We show that the problem can be described with the common
+Boltzmann hierarchy for the photon field extended by new spectral parameters --
+a step that reduces the complexity of the calculation by at least two orders of
+magnitude. Our formalism describes the effects of i) Doppler and potential
+driving, ii) spectral evolution by Compton scattering, iii) perturbed
+thermalisation and iv) anisotropic heating on the distortion anisotropies. We
+highlight some of the main physical properties of the equations and also
+outline the steps for computing CMB power spectra including distortion
+anisotropies. Limitations and extensions of the formulation are also briefly
+discussed. The novel Boltzmann hierarchy given here is the basis for a series
+of companion papers studying how distortion anisotropies evolve in the
+perturbed Universe and which physical processes could be constrained using
+future CMB imaging techniques.",2210.15308v1
+2022-11-07,Simulation of the Einstein-de Haas effect combining molecular and spin dynamics,"The spin and lattice dynamics of a ferromagnetic nanoparticle are studied via
+molecular dynamics and with semi-classical spin dynamics simulations where spin
+and lattice degrees of freedom are coupled via a dynamic uniaxial anisotropy
+term. We show that this model conserves total angular momentum, whereas spin
+and lattice angular momentum are not conserved. We carry out simulations of the
+the Einstein-de Haas effect for a Fe nanocluster with more than 500 atoms that
+is free to rotate, using a modified version of the open-source spinlattice
+dynamics code (SPILADY). We show that the rate of angular momentum transfer
+between spin and lattice is proportional to the strength of the magnetic
+anisotropy interaction. The addition of the anisotropy allows full spin-lattice
+relaxation to be achieved on previously reported timescales of \sim 100 ps and
+for tight-binding magnetic anisotropy energies comparable to those of small Fe
+nanoclusters.",2211.03706v1
+2022-11-09,Anomalous anisotropy of spin current in a cubic spin source with noncollinear antiferromagnetism,"Cubic materials host high crystal symmetry and hence are not expected to
+support anisotropy in transport phenomena. In contrast to this common
+expectation, here we report an anomalous anisotropy of spin current can emerge
+in the (001) film of Mn${_3}$Pt, a noncollinear antiferromagnetic spin source
+with face-centered cubic structure. Such spin current anisotropy originates
+from the intertwined time reversal-odd ($T$-odd) and time reversal-even
+($T$-even) spin Hall effects. Based on symmetry analyses and experimental
+characterizations of the current-induced spin torques in Mn${_3}$Pt-based
+heterostructures, we find that the spin current generated by Mn${_3}$Pt (001)
+exhibits exotic dependences on the current direction for all the spin
+components, deviating from that in conventional cubic systems. We also
+demonstrate that such an anisotropic spin current can be used to realize
+low-power spintronic applications such as the efficient field-free switching of
+the perpendicular magnetizations.",2211.04970v1
+2023-01-07,Crucial role of Fe in determining the hard magnetic properties of Nd$_2$Fe$_{14}$B,"Nd$_2$Fe$_{14}$B's unsurpassed, hard magnetic properties for a wide range of
+temperatures result from a combination of a large volume magnetization from Fe
+and a strong single-ion anisotropy from Nd. Here, using finite temperature
+first-principles calculations, we focus on the other crucial roles played by
+the Fe atoms in maintaining the magnetic order on the Nd sublattices, and hence
+the large magnetic anisotropy, and directly generating significant uniaxial
+anisotropy at high temperatures. We identify effective spins for atomistic
+modelling from the material's interacting electrons and {quantify pairwise and
+higher order, non-pairwise magnetic interactions among them. We find the Nd
+spins couple most strongly to spins on sites belonging to two specific Fe
+sublattices, 8$j_1$, 8$j_2$. Moreover the Fe 8$j_1$ sublattice also provides
+the electronic origin of the unusual, nonmonotonic temperature dependence of
+the anisotropy of Y$_2$Fe$_{14}$B.} Our work provides atomic-level resolution
+of the properties of this fascinating magnetic material.",2301.02868v1
+2023-01-08,Diffusive Pseudo-Conformal Mapping: Anisotropy-Free Transformation Thermal Media with Perfect Interface Matching,"Transformation media provide a fundamental paradigm for field regulation, but
+their tricky anisotropy challenges fabrication. Though optical conformal
+mapping has been utilized to eliminate anisotropy, two key factors still hinder
+its development in thermotics, i.e., the distinct diffusion nature and
+inevitable interface mismatching. Here, we put forth the concept of diffusive
+pseudo-conformal mapping, overcoming the inherent difference between diffusion
+and waves and achieving perfect interface matching. The proposed mapping
+directly leads to heat guiding and expanding functions with anisotropy-free
+transformation thermal media, whose feasibility is confirmed by experiments or
+simulations. Besides diverse applications, we provide a unified perspective for
+two distinct types of prevailing bilayer cloaks by uncovering their profound
+ties with pseudo-conformal mapping. These results greatly simplify the
+preparation of transformation thermotics and have implications for regulating
+other diffusion and wave phenomena.",2301.02963v1
+2023-01-16,Possible realization of hyperbolic plasmons in a few-layered rhenium disulfide,"The in-plane structural anisotropy in low-symmetric layered compound rhenium
+disulfide ($\text{ReS}_2$) makes it a candidate to host and tune
+electromagnetic phenomena specific for anisotropic media. In particular,
+optical anisotropy may lead to the appearance of hyperbolic plasmons, a highly
+desired property in optoelectronics. The necessary condition is a strong
+anisotropy of the principal components of the dielectric function, such that at
+some frequency range, one component is negative and the other is positive,
+i.e., one component is metallic, and the other one is dielectric. Here, we
+study the effect of anisotropy in $\text{ReS}_2$ and show that it can be a
+natural material to host hyperbolic plasmons in the ultraviolet frequency
+range. The operating frequency range of the hyperbolic plasmons can be tuned
+with the number of $\text{ReS}_2$ layers.",2301.06521v1
+2023-01-19,Intrinsic limits on the detection of the anisotropies of the Stochastic Gravitational Wave Background,"For any given network of detectors, and for any given integration time, even
+in the idealized limit of negligible instrumental noise, the intrinsic time
+variation of the isotropic component of the Stochastic Gravitational Wave
+Background (SGWB) induces a limit on how accurately the anisotropies in the
+SGWB can be measured. We show here how this sample limit can be calculated and
+apply this to three separate configurations of ground-based detectors placed at
+existing and planned sites. Our results show that in the idealized, best-case
+scenario individual multipoles of the anisotropies at $\ell \leq 8$ can only be
+measured to $\sim 10^{-5} - 10^{-4}$ level over 5 years of observation as a
+fraction of the isotropic component. As the sensitivity improves as the square
+root of the observation time, this poses a very serious challenge for the
+measurement of the anisotropies of SGWB of cosmological origin, even in the
+case of idealised detectors with arbitrarily low instrumental noise.",2301.08074v1
+2023-02-11,Spatial magnetization profile in spherical nanomagnets with surface anisotropy: Green's function approach,"We consider a single spherical nanomagnet and investigate the spatial
+magnetization profile $\mathbf{m}\left(\mathbf{r}\right)$ in the continuum
+approach, using the Green's function formalism. The energy of the (many-spin)
+nanomagnet comprises an isotropic exchange interaction, a uniaxial anisotropy
+in the core and N\'eel's surface anisotropy, and an external magnetic field. We
+derive a semi-analytical expression for the magnetization vector field
+$\mathbf{m}\left(\mathbf{r}\right)$ for an arbitrary position $\mathbf{r}$
+within and on the boundary of the nanomagnet, as a solution of a homogeneous
+Helmholtz equation with inhomogeneous Neumann boundary conditions.
+  ...
+  For a more plausible comparison with experiments, e.g. using the technique of
+small-angle magnetic neutron scattering, we have averaged over the direction
+solid angle and derived the spatial profile in terms of the distance $r$. We
+believe that the predictions of the present study could help to characterize
+and understand the effects of size and surface anisotropy on the magnetization
+configurations in nanomagnet assemblies such as arrays of well-spaced
+platelets.",2302.05773v3
+2023-02-13,Density jump as a function of magnetic field strength for parallel collisionless shocks with anisotropic upstream pressure,"The properties of collisionless shocks are frequently assessed in the
+magnetohydrodynamics (MHD) model. Yet, in a collisionless plasma, an ambient
+magnetic field can sustain a stable anisotropy in the upstream or the
+downstream, resulting in a departure from the MHD predicted behavior. We
+present a model allowing to derive the downstream anisotropy, hence the shock
+density jump, in terms of the upstream quantities. For simplicity, the case of
+a parallel shock in pair plasma is considered. Contrary to previous works where
+the upstream was assumed isotropic, here the upstream anisotropy
+$A=T_\perp/T_\parallel$ is a free parameter. The strong sonic shock regime is
+formally identical to the isotropic upstream case. Yet, for intermediate sonic
+Mach numbers, a variety of behaviors appear as a result of the anisotropy of
+the upstream.",2302.06521v1
+2023-02-23,In-situ Growth of Ultrathin Magnetic Films and Tuning the Magnetic Properties by Ion-sculpting,"Magnetic anisotropy is a key parameter of magnetic materials as it decides
+the response in the presence of an external magnetic field. The artificial
+tailoring of magnetic anisotropy by manipulating surface and interface
+morphology is attracting widespread interest for its application in spintronic
+and magnetic memory devices. In this perspective, the primary focus of this
+thesis has been inducing and tailoring magnetic anisotropy in thin film-based
+systems via the engineering of structure and surface/interfacial morphology.
+For this purpose, instead of multistep, expensive lithographic techniques, we
+have utilized low-energy IBE as a handy, cost-effective, and useful tool for
+producing magnetic nanostructures and tailoring its surface structure,
+morphology and magnetic anisotropy. Furthermore, we have also proposed various
+new and unconventional methods (oblique angle deposition on the rippled
+substrate, sequential deposition-erosion) for enhancement of UMA and proved its
+effectiveness via experiments. We have performed most of the present thesis
+work in-situ utilizing a UHV chamber to get genuine characteristics and
+understand their interdependencies. However, advanced synchrotron-based
+techniques such as GISAXS and NFS were also utilized to complement the in-situ
+observations.",2302.11941v1
+2023-05-02,GW_CLASS: Cosmological Gravitational Wave Background in the Cosmic Linear Anisotropy Solving System,"The anisotropies of the Cosmological Gravitational Wave Background (CGWB)
+retain information about the primordial mechanisms that source the
+gravitational waves and about the geometry and the particle content of the
+universe at early times. In this work, we discuss in detail the computation of
+the angular power spectra of CGWB anisotropies and of their cross correlation
+with Cosmic Microwave Background (CMB) anisotropies, assuming different
+processes for the generation of these primordial signals. We present an
+efficient implementation of our results in a modified version of CLASS which
+will be publicly available. By combining our new code GW_CLASS with
+MontePython, we forecast the combined sensitivity of future gravitational wave
+interferometers and CMB experiments to the cosmological parameters that
+characterize the cosmological gravitational wave background.",2305.01602v2
+2023-05-02,Probing the global 21-cm background by velocity-induced dipole and quadrupole anisotropies,"The motion of an observer in the rest frame of the cosmic 21-cm background
+induces an anisotropy in the observed background, even when the background is
+isotropic. The induced anisotropy includes a dipole and a quadrupole, in the
+order decreasing in amplitude. If observed, these multipole anisotropies can be
+used as additional probes of the spectral shape of the global 21-cm background
+for mitigating the ambiguity in the monopole spectrum probed by single-element
+radio telescopes such as EDGES and SARAS. This could also help with
+understanding the astrophysical and cosmological processes that occurred during
+the cosmic dawn and the epoch of reionization, and even improving on the
+estimation of the solar velocity and the foreground spectra. Here, we study the
+feasibility of such observations and present science drivers for the
+measurement of the 21-cm dipole and quadrupole.",2305.01672v2
+2023-05-15,Post-growth shaping and transport anisotropy in 2D InAs nanofins,"We report on the post-growth shaping of free-standing 2D InAs nanofins that
+are grown by selective-area epitaxy and mechanically transferred to a separate
+substrate for device fabrication. We use a citric acid based wet etch that
+enables complex shapes, e.g., van der Pauw cloverleaf structures, with
+patterning resolution down to 150 nm as well as partial thinning of the nanofin
+to improve the gate response. We exploit the high sensitivity of the cloverleaf
+structures to transport anisotropy to address the fundamental question of
+whether there is a measurable transport anisotropy arising from
+wurtzite/zincblende polytypism in 2D InAs nanostructures. We demonstrate a
+mobility anisotropy of order 2-4 at room temperature arising from polytypic
+stacking faults in our nanofins. Our work highlights a key materials
+consideration for devices featuring self-assembled 2D III-V nanostructures
+using advanced epitaxy methods.",2305.08309v1
+2023-05-25,The Impact of Anisotropy on Neutron Star Properties: Insights from I-f-C Universal Relations,"This study presents a universal relation for anisotropic neutron stars,
+called the $I-f-C$ relation, which accounts for the local anisotropic pressure
+using the Quasi-Local (QL) Model proposed by Horvat et al. \cite{QL_Model} to
+describe the anisotropy inside the neutron star. This study analyzes
+approximately 60 unified tabulated EoS-ensembles, spanning from relativistic to
+non-relativistic mean-field models, that comply with multimessenger constraints
+and cover a broad range of stiffness. The results indicate that the
+relationship between the parameters becomes more robust with positive
+anisotropy, while it weakens with negative anisotropy. With the help of the
+GW170817 \& GW190814 tidal deformability limit, a theoretical limit for the
+canonical $f$-mode frequency for both isotropic and anisotropic stars is
+established. For isotropic case the canonical $f$-mode frequency for event
+GW170817 \& GW190814 is $f_{1.4} = 2.605^{+0.487} _ {-0.459}\ \mathrm{kHz}$ and
+$ f_{1.4} = 2.093^{+0.150} _ {-0.125} \ \mathrm{kHz}$ respectively. These
+established relationships have the potential to serve as a reliable tool to
+limit the equation of state of nuclear matter when measurements of relevant
+observables are obtained.",2305.15724v2
+2023-06-01,Anisotropic behavior of S-wave and P-wave states of heavy quarkonia at finite magnetic field,"We studied the effect of momentum space anisotropy on heavy quarkonium states
+using an extended magnetized effective fugacity quasiparticle model (EQPM).
+Both the real and imaginary part of the potential has been modified through the
+dielectric function by including the anisotropic parameter $\xi$. The real part
+of the medium modified potential becomes more attractive in the presence of the
+anisotropy and constant magnetic field. The binding energy of the 1S, 2S, and
+1P quarkonium states including anisotropy effects for both the oblate and the
+isotropic case were studied. We find that the binding energy of quarkonium
+states becomes stronger in the presence of anisotropy. However, the magnetic
+field is found to reduce the binding energy. The thermal width of the
+charmonium and bottomonium 1S states have been studied at constant magnetic
+field eB = 0.3 GeV2 for isotropic and prolate cases. The effect of magnetic
+field on the mass spectra of the 1P state for the oblate case was also
+examined. The dissociation temperature for the 1S, 2S, and 1P charmonium and
+bottomonium have been determined to be higher for the oblate case with respect
+to the isotropic case",2306.00908v1
+2023-06-13,Heavy quark radiation in an anisotropic hot QCD medium,"The impact of momentum anisotropy on the heavy quarks (HQs) dynamics has been
+investigated in a hot QCD medium while considering both collisional and
+radiative processes within the ambit of the Fokker-Planck approach. The
+relative orientation of the HQs motion (momentum vector) with respect to the
+direction of anisotropy is responsible for the character of transport
+coefficients. Therefore, the drag and diffusion coefficients of the HQs are
+decomposed, respectively, into two and four components by considering a general
+tensor basis. Each component of the drag and diffusion coefficient of the HQs
+has been analyzed in detail. It is observed that the anisotropy has a
+significant impact on the transport coefficients of the HQ for both the
+collisional and the radiational processes. The nuclear suppression factor,
+$R_{AA}$, has been computed considering the anisotropic medium. It is observed
+that the momentum anisotropy affects the $R_{AA}$ of the HQs significantly in
+both elastic and inelastic cases.",2306.07966v2
+2023-06-20,Engineering magnetic anisotropy and the surface of epitaxial Fe films using ion beam erosion; unveiling self-assembly and tunability,"The engineering of surface morphology and structure of the thin film is one
+of the essential technological assets for regulating the physical properties
+and functionalities of thin film-based devices. This study investigates the
+evolution of surface structure and magnetic anisotropy in epitaxially grown
+ultrathin Fe films on MgO (001) substrates subjected to multiple cycles of ion
+beam erosion (IBE) after growth. Ultrathin Fe film grows in 3D island mode and
+exhibits intrinsic fourfold magnetic anisotropy. After a few cycles of IBE, the
+film displays an induced uniaxial magnetic anisotropy that leads to a split in
+the hysteresis loop. In addition, clear and conclusive evidence of IBE mediated
+(2x2) reconstruction of the Fe surface has been observed. We also demonstrate
+that thermal annealing can reversibly tune the induced UMA and surface
+reconstruction. The feasibility of the IBE technique by properly selecting ion
+beam parameters for modification of surface structure has been highlighted
+apart from conventional methods of tailoring the morphology for tuning of UMA.
+Thus, the present work paves a way to explore the IBE-induced self-assembling
+phenomena further.",2306.11516v1
+2023-07-14,Photon and dilepton emission anisotropy for magnetized quark-gluon plasma,"We study the higher-order anisotropy coefficients $v_4$ and $v_6$ in the
+photon and dilepton emission from a hot magnetized quark-gluon plasma. Together
+with the earlier predictions for $v_2$, these results show a distinctive
+pattern of the anisotropy coefficients in several kinematic regimes. In the
+case of photon emission, nonzero coefficients $v_n$ (with even $n$) have
+opposite signs at small and large values of the transverse momentum (i.e.,
+$k_T\lesssim \sqrt{|eB|}$ and $k_T\gtrsim \sqrt{|eB|}$, respectively).
+Additionally, the $v_n$ signs alternate with increasing $n$, and their
+approximate values decrease as $1/n^2$ in magnitude. The anisotropy of dilepton
+emission is well-pronounced only at large transverse momenta and small
+invariant masses (i.e., when $k_T\gtrsim \sqrt{|eB|}$ and $M\lesssim
+\sqrt{|eB|}$). The corresponding $v_4$ and $v_6$ coefficients are of the same
+magnitude and show a similar sign-alternative pattern with increasing $n$ as in
+the photon emission.",2307.07557v1
+2023-07-21,Tailoring giant quantum transport anisotropy in disordered nanoporous graphenes,"During the last 15 years bottom-up on-surface synthesis has been demonstrated
+as an efficient way to synthesize carbon nanostructures with atomic precision,
+opening the door to unprecedented electronic control at the nanoscale.
+Nanoporous graphenes (NPGs) fabricated as two-dimensional arrays of graphene
+nanoribbons (GNRs) represent one of the key recent breakthroughs in the field.
+NPGs interestingly display in-plane transport anisotropy of charge carriers,
+and such anisotropy was shown to be tunable by modulating quantum interference.
+Herein, using large-scale quantum transport simulations, we show that
+electrical anisotropy in NPGs is not only resilient to disorder but can further
+be massively enhanced by its presence. This outcome paves the way to systematic
+engineering of quantum transport in NPGs as a novel concept for efficient
+quantum devices and architectures.",2307.11480v1
+2023-07-31,"Multi-particle correlations, cumulants, and moments sensitive to fluctuations in rare-probe azimuthal anisotropy in heavy ion collisions","Correlations of two or more particles have been an essential tool for
+understanding the hydrodynamic behavior of the quark-gluon plasma created in
+ultra-relativistic nuclear collisions. In this paper, we extend that framework
+to introduce a mathematical construction of multi-particle correlators that
+utilize correlations between arbitrary numbers of particles of interest (e.g.
+particles selected for their strangeness, heavy flavor, and conserved charges)
+and inclusive reference particles to estimate the azimuthal anisotropies of
+rare probes. To estimate the fluctuations and correlations in the azimuthal
+anisotropies of these particle of interest, we use these correlators in a
+system of cumulants, raw moments, and central moments. We finally introduce two
+classes of observables that can compare the fluctuations in the azimuthal
+anisotropies of particles of interest with reference particles at each order.",2307.16796v2
+2023-08-07,Frustration relief and reorientation transition in the kagome-like dolerophanite Cu$_2$OSO$_4$,"We present a theoretical study of dolerophanite Cu$_2$OSO$_4$, a layered
+kagome-like spin-$\frac{1}{2}$ magnetic insulator that can be described either
+as a system of chains coupled through dimers or as a kagome lattice where every
+third spin is replaced by a ferromagnetic spin dimer. Building on insights from
+ab initio calculations, classical numerical minimizations, and semiclassical
+expansions, we arrive at a minimal microscopic description that accounts for
+the experimental data reported so far, including the nature of the magnetic
+order, the reported spin length, and the observed anisotropy. The latter arises
+by a peculiar competition between the antisymmetric (Dzyaloshinskii-Moriya) and
+the symmetric part of the exchange anisotropy, which gives rise to a two-step
+re-orientation process involving two successive continuous phase transitions.
+Our work uncovers mechanisms stabilizing canted ferrimagnetic order in kagome
+systems, and highlights strong magnetic anisotropy in the presence if
+dissimilar magnetic orbitals on crystallographically nonequivalent Cu sites. We
+also show how these anisotropy terms affect the spin-wave spectrum and how they
+can be tracked experimentally.",2308.03599v2
+2023-08-21,"Anisotropies, large and small","We report on several new results using anisotropies of UHECRs. We improve and
+extend the work of Ding, Globus and Farrar, who modeled the UHECR dipole
+assuming sources follow the dark matter distribution, accounting for
+deflections in the Galactic and extragalactic magnetic fields but using a
+simplified treatment of interactions during propagation. The work presented
+here employs an accurate and self-consistent treatment of the evolution of
+composition during propagation, allows for and explores the impact of ""bias"" in
+the relation between UHECR sources and the dark matter distribution, and
+investigates the possible generation of arrival-direction-dependent composition
+anisotropies. Limits on the source number density consistent with the observed
+anisotropies are derived for the case where UHECR sources follow the dark
+matter distribution, and compared to a homogeneous source distribution case.",2308.10678v1
+2023-08-22,Measures of azimuthal anisotropy in high-energy collisions,"Azimuthal anisotropy is a key observation made in ultrarelativistic heavy-ion
+collisions. This phenomenon has played a crucial role in the development of the
+field over the last two decades. In addition to its interest for studying the
+quark-gluon plasma, which was the original motivation, it is sensitive to the
+properties of incoming nuclei, in particular to the nuclear deformation and to
+the nuclear skin. The azimuthal anisotropy is therefore of crucial importance
+when relating low-energy nuclear structure to high-energy nuclear collisions.
+This article is an elementary introduction to the various observables used in
+order to characterize azimuthal anisotropy, which go under the names of
+$v_2\{2\}$, $v_3\{2\}$, $v_2\{4\}$, etc. The intended audience is primarily
+physicists working in the field of nuclear structure.",2308.11674v2
+2023-08-28,Azimuthal Anisotropy at high transverse momentum in $p$-$p$ and $p$-$A$ collisions,"We explore the possibility that the initial transverse momentum distribution
+of unpolarized and polarized partons within unpolarized nucleons, both with and
+without the anisotropy of unpolarized hadrons produced in the fragmentation of
+outgoing partons, could lead to the observed azimuthal anisotropy of high
+transverse momentum (high-$p_T$) hadrons produced in high energy proton-proton
+($p$-$p$) or proton-ion ($p$-$A$) collisions. Including simple Gaussian forms
+for transverse momentum dependent parton distribution functions (PDF) and
+fragmentation functions, and assuming an $A^{1/3}$ enhancement of a PDF in
+$p$-$Pb$ collisions, we show that the observed anisotropy, with \emph{no
+modification} to the angle integrated spectra ($R_{pA}=1$) for 5~GeV~$\lesssim
+p_T\lesssim 50$~GeV, can be straightforwardly understood as arising from a few
+processes dominated by gluon-gluon to gluon-gluon scattering.",2308.14702v4
+2023-09-01,Kinematic anisotropies and pulsar timing arrays,"Doppler anisotropies, induced by our relative motion with respect to the
+source rest frame, are a guaranteed property of stochastic gravitational wave
+backgrounds of cosmological origin. If detected by future pulsar timing array
+measurements, they will provide interesting information on the physics sourcing
+gravitational waves, which is hard or even impossible to extract from
+measurements of the isotropic part of the background only. We analytically
+determine the pulsar response function to kinematic anisotropies, including
+possible effects due to parity violation, to features in the frequency
+dependence of the isotropic part of the spectrum, as well as to the presence of
+extra scalar and vector polarizations. For the first time, we show how the
+sensitivity to different effects crucially depends on the pulsar configuration
+with respect to the relative motion among frames. Correspondingly, we propose
+examples of strategies of detection, each aimed at exploiting future
+measurements of kinematic anisotropies for characterizing distinct features of
+the cosmological gravitational wave background.",2309.00403v3
+2023-09-06,Shaping magnetization dynamics in a planar square dot by adjusting its surface anisotropy,"A planar square dot is one of the simplest structures confined to three
+dimensions. Despite its geometrical simplicity, the description of the spin
+wave modes in this structure is not trivial due to the competition of dipolar
+and exchange interactions. An additional factor that makes this description
+challenging are the boundary conditions depend both on non-local dipolar
+interactions and local surface parameters such as surface anisotropy. In the
+presented work, we showed how the surface anisotropy applied at the lateral
+faces of the dot can tune the frequency of fundamental mode in the planar CoFeB
+dot, magnetized in an out-of-plane direction. Moreover, we analyzed the spin
+wave profile of the fundamental mode and the corresponding dynamic stray field.
+We showed that the asymmetric application of surface anisotropy produces an
+asymmetric profile of dynamic stray field for square dot and can be used to
+tailor inter-dot coupling. The calculations were performed with the use of the
+finite-element method.",2309.02984v1
+2023-09-09,Anisotropy-assisted thermodynamic advantage of a local-spin thermal machine,"We study quantum Otto thermal machines with a two-spin working system coupled
+by anisotropic interaction. Depending on the choice of different parameters,
+the quantum Otto cycle can function as different thermal machines, including a
+heat engine, refrigerator, accelerator and heater. We aim to investigate how
+the anisotropy plays a fundamental role in the performance of the quantum Otto
+engine operating in different time scales. We find that while the efficiency of
+the engine efficiency increases with the increase in anisotropy for the
+quasistatic operation, quantum internal friction and incomplete thermalization
+degrade the performance in a finite time cycle. Further, we study the QOE with
+one of the spins, the local spin, as the working system. We show that the
+efficiency of such an engine can surpass the standard quantum Otto limit, along
+with maximum power, thanks to the anisotropy. This can be attributed to quantum
+interference effects. We demonstrate that the enhanced performance of a
+local-spin QOE originates from the same interference effects, as in a
+measurement-based QOE for their finite time operation.",2309.04757v1
+2023-09-12,Anisotropy-assisted magnon condensation in ferromagnetic thin films,"We theoretically demonstrate that adding an easy-axis magnetic anisotropy
+facilitates magnon condensation in thin yttrium iron garnet (YIG) films.
+Dipolar interactions in a quasi-equilibrium state stabilize room-temperature
+magnon condensation in YIG. Even though the out-of-plane easy-axis anisotropy
+generally competes with the dipolar interactions, we show that adding such
+magnetic anisotropy may even assist the generation of the magnon condensate
+electrically via the spin transfer torque mechanism. We use analytical
+calculations and micromagnetic simulations to illustrate this effect. Our
+results may explain the recent experiment on Bi-doped YIG and open a pathway
+toward applying current-driven magnon condensation in quantum spintronics.",2309.05982v3
+2023-10-18,"First-principles study of the magnetic anisotropy of ultrathin B-, C-, and N-doped FeCo films","Iron-based layered systems are of great interest because of their ability to
+tune effective material parameters such as magnetic anisotropy energy (MAE).
+The influence of the crystallographic structure of Fe, its thickness, and the
+presence of other layers above and below the Fe layer on magnetic parameters,
+such as the MAE of the studied system, is an intriguing and important topic
+from an application point of view. Here, we present a density functional theory
+(DFT) study of the magnetic anisotropy of nine-monolayer Fe, FeCo, and FeCo
+films with B, C, and N dopants placed in octahedral interstitial positions. The
+theoretical study is based on calculations using the full-potential
+local-orbital code FPLO and the generalized gradient approximation. The
+chemical disorder in the FeCo layers was modeled using the virtual crystal
+approximation. The structures of the layers were subjected to optimization of
+the geometry of the interlayer spacings and the neighborhood of the dopant
+sites. We determined the local magnetic moments and the excess charge at each
+layer position. We also identified the influence of dopant atoms on the
+magnetic properties of FeCo layers, such as magnetization and magnetic
+anisotropy.",2310.12242v1
+2023-10-23,Anisotropies in Scalar-Induced Gravitational-Wave Background from Inflaton-Curvaton Mixed Scenario with Sound Speed Resonance,"We propose a new model to generate large anisotropies in the scalar-induced
+gravitational wave (SIGW) background via sound speed resonance in the
+inflaton-curvaton mixed scenario. Cosmological curvature perturbations are not
+only exponentially amplified at a resonant frequency, but also preserve
+significant non-Gaussianity of local type described by $f_{\mathrm{nl}}$.
+Besides a significant enhancement of energy-density fraction spectrum, large
+anisotropies in SIGWs can be generated, because of super-horizon modulations of
+the energy density due to existence of primordial non-Gaussianity. A reduced
+angular power spectrum $\tilde{C}_{\ell}$ could reach an amplitude of
+$[\ell(\ell+1)\tilde{C}_{\ell}]^{1/2} \sim 10^{-2}$, leading to potential
+measurements via planned gravitational-wave detectors such as DECIGO. The large
+anisotropies in SIGWs would serve as a powerful probe of the early universe,
+shedding new light on the inflationary dynamics, primordial non-Gaussianity,
+and primordial black hole dark matter.",2310.14606v3
+2023-10-25,Intrinsic Piezoelectric Anisotropy of Tetragonal ABO3 Perovskites: A High-Throughput Study,"A comprehensive understand of the intrinsic piezoelectric anisotropy stemming
+from diverse chemical and physical factors is a key step for the rational
+design of highly anisotropic materials. We performed high-throughput
+calculations on tetragonal ABO3 perovskites to investigate the piezoelectricity
+and the interplay between lattice, displacement, polarization and elasticity.
+Among the 123 types of perovskites, the structural tetragonality is naturally
+divided into two categories: normal tetragonal (c/a ratio < 1.1) and
+super-tetragonal (c/a ratio > 1.17), exhibiting distinct ferroelectric,
+elastic, and piezoelectric properties. Charge analysis revealed the mechanisms
+underlying polarization saturation and piezoelectricity suppression in the
+super-tetragonal region, which also produces an inherent contradiction between
+high d33 and large piezoelectric anisotropy ratio |d33/d31|. The polarization
+axis and elastic softness direction jointly determine the maximum longitudinal
+piezoelectric response d33 direction. The validity and deficiencies of the
+widely utilized |d33/d31| ratio for representing piezoelectric anisotropy were
+reevaluated.",2310.16591v1
+2023-10-29,Impact of Medium Anisotropy on Quarkonium Dissociation and Regeneration,"Quarkonium production in ultra-relativistic collisions plays a crucial role
+in probing the existence of hot QCD matter. This study explores quarkonia
+states dissociation and regeneration in the hot QCD medium while considering
+momentum anisotropy. The net quarkonia decay width ($\Gamma_{D}$) arises from
+two essential processes: collisional damping and gluonic dissociation. The
+quarkonia regeneration includes the transition from octet to singlet states
+within the anisotropic medium. Our study utilizes a medium-modified potential
+that incorporates anisotropy via particle distribution functions. This modified
+potential gives rise to collisional damping for quarkonia due to the
+surrounding medium, as well as the transition of quarkonia from singlet to
+octet states due to interactions with gluons. Furthermore, we employ the
+detailed balance approach to investigate the regeneration of quarkonia within
+this medium. Our comprehensive analysis spans various temperature settings,
+transverse momentum values, and anisotropic strengths. Notably, we find that,
+in addition to medium temperatures and heavy quark transverse momentum,
+anisotropy significantly influences the dissociation and regeneration of
+various quarkonia states.",2310.18909v1
+2023-11-11,Single-Phase L1$_{0}$-Ordered High Entropy Thin Films with High Magnetic Anisotropy,"The vast high entropy alloy (HEA) composition space is promising for
+discovery of new material phases with unique properties. We explore the
+potential to achieve rare-earth-free high magnetic anisotropy materials in
+single-phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally
+oxidized Si/SiO$_{2}$ substrates at room temperature are magnetically soft,
+with a coercivity on the order of 10 Oe. After post-deposition rapid thermal
+annealing (RTA), the films exhibit a single face-centered-cubic (fcc) phase,
+with an almost 40-fold increase in coercivity. Inclusion of 50 at.% Pt in the
+film leads to ordering of a single L1$_{0}$ high entropy intermetallic phase
+after RTA, along with high magnetic anisotropy and a 3 orders of magnitude
+coercivity increase. These results demonstrate a promising HEA approach to
+achieve high magnetic anisotropy materials using RTA.",2311.06618v2
+2023-11-13,Magnetogenesis from Anisotropic Universe,"The existence of large-scale anisotropy can not be ruled out by the cosmic
+microwave background (CMB) radiation. Over the years, several models have been
+proposed in the context of anisotropic inflation to account for CMB's cold spot
+and hemispheric asymmetry. However, any small-scale anisotropy, if exists
+during inflation, is not constrained due to its nonlinear evolution in the
+subsequent phase. This small-scale anisotropy during inflation can play a
+non-trivial role in giving rise to the cosmic magnetic field, which is the
+subject of our present study. Assuming a particular phenomenological form of an
+anisotropic inflationary universe, we have shown that it can generate a
+large-scale magnetic field at $1$-Mpc scale with a magnitude $\sim 4\times
+10^{-20}~G$, within the observed bound. Because of the anisotropy, the
+conformal flatness property is lost, and the Maxwell field is generated even
+without explicit coupling. This immediately resolves the strong coupling
+problem in the standard magnetogenesis scenario. In addition, assuming very low
+conductivity during the reheating era, we can further observe the evolution of
+the electromagnetic field with the equation of state (EoS) $\omega_{eff}$ and
+its effects on the present-day magnetic field.",2311.07685v1
+2023-12-05,Magnetic instability under ferroaxial moment,"Magnetic anisotropy is one of the important factors in determining magnetic
+structures. A type of magnetic anisotropy is closely related to the symmetry of
+crystals. We theoretically investigate magnetic anisotropy and its related
+magnetic instability arising from an electric axial moment, which appears under
+the breaking of the mirror symmetry parallel to the moment but does not require
+the breakings of both spatial inversion and time-reversal symmetries. By
+performing perturbation and mean-field calculations in a complementary way, we
+show the appearance of the in-plane magnetic anisotropy when the electric axial
+moment occurs, which tends to tilt in-plane spin moments from the crystal axes
+in collaboration with relativistic spin--orbit coupling. We demonstrate such a
+tendency for single-site and four-site cluster models, the latter of which
+leads to the instability toward a spin vortex phase accompanying magnetic
+monopole and magnetic toroidal dipole.",2312.02444v1
+2024-01-23,Universal relations for anisotropic interacting quark stars,"Interacting quark stars, which are entirely composed of interacting quark
+matter including perturbative QCD corrections and color superconductivity, can
+meet constraints from various pulsar observations. In realistic scenarios,
+pressure anisotropies are expected in the star's interior. Recently, the
+stellar structural properties of anisotropic interacting quark stars have been
+investigated. In this study, we further explore the universal relations (URs)
+related to the moment of inertia $I$, tidal deformability $\Lambda$,
+compactness $C$, and the $f$-mode nonradial pulsation frequency for such stars.
+Our results reveal that these approximate URs generally hold, being insensitive
+to both the EOS variations as well as to the presence of anisotropy.
+Specifically, we find that more positive anisotropy tends to enhance the
+$I-\Lambda$ and $I-C$ URs, but weakens the $C-\Lambda$ UR. For all the URs
+involving $f$-mode frequency, we find that they are enhanced by the inclusion
+of anisotropy (whether positive or negative).",2401.12519v1
+2024-02-05,Bifurcation to complex dynamics in largely modulated voltage-controlled parametric oscillator,"An experimental demonstration of a parametric oscillation of a magnetization
+in a ferromagnet was performed recently by applying a microwave voltage,
+indicating the potential to be applied in a switching method in non-volatile
+memories. In the previous works, the modulation of a perpendicular magnetic
+anisotropy field produced by the microwave voltage was small compared with an
+external magnetic field pointing in an in-plane direction. A recent trend is,
+however, opposite, where an efficiency of the voltage controlled magnetic
+anisotropy (VCMA) effect is increased significantly by material research and
+thus, the modulated magnetic anisotropy field can be larger than the external
+magnetic field. Here, we solved the Landau-Lifshitz-Gilbert equation
+numerically and investigated the magnetization dynamics driven under a wide
+range of the microwave VCMA effect. We evaluated bifurcation diagrams, which
+summarize local maxima of the magnetization dynamics. For low modulation
+amplitudes, the local maximum is a single point because the dynamics is the
+periodic parametric oscillation. The bifurcation diagrams show distributions of
+the local maxima when the microwave magnetic anisotropy field becomes larger
+than the external magnetic field. The appearance of this broadened distribution
+indicates complex dynamics such as chaotic and transient-chaotic behaviors,
+which were confirmed from an analysis of temporal dynamics.",2402.02742v1
+2024-02-12,Quarkonia dissociation at finite magnetic field in the presence of momentum anisotropy,"In this study, we investigate the potential of heavy quarkonia within a
+magnetized hot QGP medium having finite momentum anisotropy. The phenomenon of
+inverse magnetic catalysis is introduced into the system, influencing the
+magnetic field-modified Debye mass and thereby altering the effective quark
+masses. Concurrently, the impact of momentum anisotropy in the medium is
+considered that influence the particle distribution in the medium. The thermal
+decay width and dissociation temperature of quarkonium states, specifically the
+1S and 2S states of charmonium and bottomonium, are computed. Our results
+reveal that both momentum anisotropy and the inverse magnetic catalysis effects
+play a significant role in modifying the thermal decay width and dissociation
+temperature of these heavy quarkonia states.",2402.07848v1
+2024-02-14,Anisotropy Scaling Functions in Heavy-Ion Collisions: Insights into the `Ultra-Central Flow Puzzle' and Constraints on Transport Coefficients and Nuclear Deformation,"Anisotropy scaling functions, derived from extensive measurements of
+transverse momentum- and centrality-dependent anisotropy coefficients
+$v_2(p_T,\text{cent})$ and $v_3(p_T,\text{cent})$ in Pb+Pb collisions at 5.02
+and 2.76 TeV, and Xe+Xe collisions at 5.44 TeV at the LHC, shed light on the
+'ultra-central flow puzzle'. These functions amalgamate diverse measurements
+into a unified curve, elucidating anisotropy attenuation across the full $p_T$
+and centrality range and unveiling dependencies on key factors including
+initial-state eccentricities ($\varepsilon_{n}$), dimensionless size
+($\mathbb{R}$), radial flow, viscous correction to the thermal distribution
+function ($\delta_f$), the medium's stopping power ($\hat{q}$), and specific
+shear viscosity ($\eta/s$). Their analysis provides distinct insights into
+transport coefficients and nucleus deformation constraints.",2402.09389v1
+2024-02-25,Effect of Magnetic Anisotropy Constants on Skyrmion Formation in Co/Pt,"Skyrmions, which are topologically stable magnetic structures, have
+manifested promising features to be used as an information carrier in new-age,
+non-volatile data storage devices. In this article, we show how the creation
+and stability of skyrmion can be manipulated by external stimuli (here,
+nano-second current pulse). Co/Pt square nano-structure with Co free layer
+thickness in the range 1 nm to 5 nm and first and second-order anisotropy
+constants are taken to study the controlled creation of skyrmions. The
+magnetization dynamics controlled by the current-induced spin transfer torque
+help to nucleate skyrmions by transformation from perpendicularly magnetized
+ground state to a stable state of isolated skyrmions via complex transformation
+of Neel wall following its image inversion. Compared with the first-order
+anisotropy alone, how the higher-order anisotropy constants (up to second
+order) impact the relaxed state of a system has been discussed.",2402.16060v1
+2024-02-27,"Impact of strong magnetic field, baryon chemical potential, and medium anisotropy on polarization and spin alignment of hadrons","The recent observation of global polarization of $\Lambda$ ($\bar{\Lambda}$)
+hyperons and spin alignment of $\phi$ and $K^{*0}$ vector mesons create
+remarkable interest in investigating the particle polarization in the
+relativistic fluid produced in heavy-ion collisions at GeV/TeV energies. Among
+other sources of polarization, the Debye mass of a medium plays a crucial role
+in particle polarization. Any modification brought to the effective mass due to
+the temperature, strong magnetic field (eB), baryonic chemical potential
+($\mu_{B}$), and medium anisotropy ($\xi$), vorticity, etc., certainly affects
+the particle polarization. In this work, we explore the global hyperon
+polarization and the spin alignment of vector mesons corresponding to the
+strong magnetic field, baryonic chemical potential, and medium anisotropy. We
+find that the degree of polarization is flavor-dependent for hyperons.
+Meanwhile, vector meson spin alignment depends on the hadronization mechanisms
+of initially polarized quarks and anti-quarks. Medium anisotropy significantly
+changes the degree of polarization in comparison with the magnetic field and
+baryon chemical potential.",2402.17344v1
+2001-06-30,Effects of Foreground Contamination on the Cosmic Microwave Background Anisotropy Measured by MAP,"We study the effects of diffuse Galactic, far-infrared extragalactic source,
+and radio point source emission on the cosmic microwave background (CMB)
+anisotropy data anticipated from the MAP experiment. We focus on the
+correlation function and genus statistics measured from mock MAP
+foreground-contaminated CMB anisotropy maps generated in a spatially-flat
+cosmological constant dominated cosmological model. Analyses of the simulated
+MAP data at 90 GHz (0.3 deg FWHM resolution smoothed) show that foreground
+effects on the correlation function are small compared with cosmic variance.
+However, the Galactic emission, even just from the region with |b| > 20 deg,
+significantly affects the topology of CMB anisotropy, causing a negative genus
+shift non-Gaussianity signal. Given the expected level of cosmic variance, this
+effect can be effectively reduced by subtracting existing Galactic foreground
+emission models from the observed data. IRAS and DIRBE far-infrared
+extragalactic sources have little effect on the CMB anisotropy. Radio point
+sources raise the amplitude of the correlation function considerably on scales
+below 0.5 deg. Removal of bright radio sources above a 5 \sigma detection limit
+effectively eliminates this effect. Radio sources also result in a positive
+genus curve asymmetry (significant at 2 \sigma) on 0.5 deg scales. Accurate
+radio point source data is essential for an unambiguous detection of CMB
+anisotropy non-Gaussianity on these scales. Non-Gaussianity of cosmological
+origin can be detected from the foreground-subtracted CMB anisotropy map at the
+2 \sigma level if the measured genus shift parameter |\Delta\nu| >= 0.02 (0.04)
+or if the measured genus asymmetry parameter |\Delta g| >= 0.03 (0.08) on a 0.3
+(1.0) deg FWHM scale.",0107004v2
+2006-10-05,Fundamental Magnetic Properties and Structural Implications for Nanocrystalline Fe-Ti-N Thin Films,"The magnetization (M) as a function of temperature (T) from 2 to 300 K and
+in-plane field (H) up to 1 kOe, room temperature easy and hard direction
+in-plane field hysteresis loops for fields between -100 and +100 Oe, and 10 GHz
+ferromagnetic resonance (FMR) profiles have been measured for a series of
+soft-magnetic nano-crystalline 50 nm thick Fe-Ti-N films made by magnetron
+sputtering in an in-plane field. The nominal titanium concentration was 3 at. %
+and the nitrogen concentrations (xN) ranged from zero to 12.7 at. %. The
+saturation magnetization (Ms) vs. T data and the extracted exchange parameters
+as a function of xN are consistent with a lattice expansion due to the addition
+of interstitial nitrogen in the body-centered-cubic (bcc) lattice and a
+structural transition to body-centered-tetragonal (bct) in the 6-8 at. %
+nitrogen range. The hysteresis loop and FMR data show a consistent picture of
+the changes in both the uniaxial and cubic anisotropy as a function of xN.
+Films with xN > 1.9 at. % show an overall uniaxial anisotropy, with an
+anisotropy field parameter Hu that increases with xN. The corresponding
+dispersion averaged uniaxial anisotropy energy density parameter <Ku> = HuMs/2
+is a linear function of xN, with a rate of increase of 950 erg/cm3 per at. %
+nitrogen. The estimated uniaxial anisotropy energy per nitrogen atom is 30
+J/mol, a value consistent with other systems. For xN below 6 at. %, the scaling
+of coercive force Hc data with the sixth power of the grain size D indicate a
+grain averaged effective cubic anisotropy energy density parameter <K1> that is
+about an order of magnitude smaller that the nominal K1 values for iron, and
+give a quantitative <K1> vs. D response that matches predictions for exchange
+coupled random grains with cubic anisotropy.",0610160v1
+2007-03-29,Anomalous scaling of a passive scalar advected by the turbulent velocity field with finite correlation time and uniaxial small-scale anisotropy,"The influence of uniaxial small-scale anisotropy on the stability of the
+scaling regimes and on the anomalous scaling of the structure functions of a
+passive scalar advected by a Gaussian solenoidal velocity field with finite
+correlation time is investigated by the field theoretic renormalization group
+and operator product expansion within one-loop approximation. Possible scaling
+regimes are found and classified in the plane of exponents $\epsilon-\eta$,
+where $\epsilon$ characterizes the energy spectrum of the velocity field in the
+inertial range $E\propto k^{1-2\epsilon}$, and $\eta$ is related to the
+correlation time of the velocity field at the wave number $k$ which is scaled
+as $k^{-2+\eta}$. It is shown that the presence of anisotropy does not disturb
+the stability of the infrared fixed points of the renormalization group
+equations which are directly related to the corresponding scaling regimes. The
+influence of anisotropy on the anomalous scaling of the structure functions of
+the passive scalar field is studied as a function of the fixed point value of
+the parameter $u$ which represents the ratio of turnover time of scalar field
+and velocity correlation time. It is shown that the corresponding one-loop
+anomalous dimensions, which are the same (universal) for all particular models
+with concrete value of $u$ in the isotropic case, are different (nonuniversal)
+in the case with the presence of small-scale anisotropy and they are continuous
+functions of the anisotropy parameters, as well as the parameter $u$. The
+dependence of the anomalous dimensions on the anisotropy parameters of two
+special limits of the general model, namely, the rapid-change model and the
+frozen velocity field model, are found when $u\to \infty$ and $u\to 0$,
+respectively.",0703063v1
+2008-08-29,Needlet Detection of Features in WMAP CMB Sky and the Impact on Anisotropies and Hemispherical Asymmetries,"We apply spherical needlets to the Wilkinson Microwave Anisotropy Probe
+5-year cosmic microwave background (CMB) dataset, to search for imprints of
+non-isotropic features in the CMB sky. We use the needlets localization
+properties to resolve peculiar features in the CMB sky and to study how these
+features contribute to the anisotropy power spectrum of the CMB. In addition to
+the now well-known ""cold spot"" of the CMB map in the southern hemisphere, we
+also find two hot spots at greater than 99% confidence level, again in the
+southern hemisphere and closer to the Galactic plane. While the cold spot
+contributes to the anisotropy power spectrum in the multipoles between l=6 to
+l=33, the hot spots are found to be dominating the anisotropy power in the
+range between l=6 and l=18. Masking both the cold and the two hot spots results
+in a reduction by about 15% in the amplitude of the angular power spectrum of
+CMB around l=10. The resulting changes to the cosmological parameters when the
+power spectrum is estimated masking these features (in addition to the WMAP
+team's KQ85 mask) are within the 1$\sigma$ errors published with the WMAP mask
+only. We also study the asymmetry between the angular power spectra evaluated
+on the northern and southern hemispheres. When the features detected by
+needlets are masked, we find that the difference in the power, measured in
+terms of the anisotropy variance between l=4 and l=18, is reduced by a factor
+2. We make available a mask related to needlet features for more detailed
+studies on asymmetries in the CMB anisotropy sky.",0809.0010v2
+2013-07-08,Dipole anisotropy in sky brightness and source count distribution in radio NVSS data,"We study the dipole anisotropy in number counts and flux density weighted
+number counts {or sky brightness} in the NRAO VLA Sky Survey (NVSS) data. The
+dipole anisotropy is expected due to our local motion with respect to the CMBR
+rest frame. We analyse data with an improved fit to the number density, n(S),
+as a function of the flux density S, which allows deviation from a pure power
+law behaviour. We also impose more stringent cuts to remove the contribution
+due to clustering dipole. In agreement with earlier results, we find that the
+amplitude of anisotropy is significantly larger in comparison to the prediction
+based on CMBR measurements. The extracted speed is found to be roughly 3 times
+the speed corresponding to CMBR. The significance of deviation is smaller,
+roughly 2 sigma, in comparison to earlier estimates. For the cut, S>30 mJy, the
+speed is found to be $1110\pm370$ Km/s using the source count analysis. The
+direction of the dipole anisotropy is found to be approximately in agreement
+with CMBR. We find that the results are relatively insensitive to the lower as
+well as upper limit imposed on the flux density. Our results suggest that the
+Universe is intrinsically anisotropic with the axis of anisotropy axis pointing
+roughly towards the CMBR dipole direction. Finally we present a method which
+may allow an independent extraction of the local speed and an intrinsic dipole
+anisotropy, provided a larger data set becomes available in future.",1307.1947v4
+2013-11-22,Effects of anisotropy on gravitational infall in galaxy clusters using an exact general relativistic model,"We study the effects and implications of anisotropies at the scale of galaxy
+clusters by building an exact general relativistic model of a cluster using the
+inhomogeneous and anisotropic Szekeres metric. The model is built from a
+modified Navarro-Frenk-White (NFW) density profile. We compare this to a
+corresponding spherically symmetric structure in the Lemaitre-Tolman (LT) model
+and quantify the impact of introducing varying levels of anisotropy. We examine
+two physical measures of gravitational infall -- the growth rate of density and
+the velocity of the source dust in the model. We introduce a generalization of
+the LT dust velocity profile for the Szekeres metric and demonstrate its
+consistency with the growth rate of density. We find that the growth rate of
+density in one substructure increases by 0.5%, 1.5%, and 3.75% for 5%, 10%, and
+15% levels of introduced anisotropy, which is measured as the fractional
+displaced mass relative to the spherically symmetric case. The infall velocity
+of the dust is found to increase by 2.5, 10, and 20 km/s (0.5%, 2%, and 4.5%),
+respectively, for the same three levels of anisotropy. This response to the
+anisotropy in a structure is found to be strongly nonlinear with respect to the
+strength of anisotropy. These relative velocities correspond to an equivalent
+increase in the total mass of the spherically symmetric structure of 1%, 3.8%,
+and 8.4%, indicating that not accounting for the presence of anisotropic mass
+distributions in cluster models can strongly bias the determination of physical
+properties like the total mass.",1311.5651v2
+2015-12-09,Anisotropy of X-ray bursts from neutron stars with concave accretion disks,"Emission from neutron stars and accretion disks in low-mass X-ray binaries is
+not isotropic. The non-spherical shape of the disk as well as blocking of the
+neutron star by the disk and vice versa cause the observed flux to depend on
+the inclination angle of the disk with respect to the line of sight. This is of
+special importance for the interpretation of Type I X-ray bursts, which are
+powered by the thermonuclear burning of matter accreted onto the neutron star.
+Because part of the X-ray burst is reflected off the disk, the observed burst
+flux depends on the anisotropies for both direct emission from the neutron star
+and reflection off the disk. This influences measurements of source distance,
+mass accretion rate, and constraints on the neutron star equation of state.
+Previous studies made predictions of the anisotropy factor for the total burst
+flux, assuming a geometrically flat disk. Recently, detailed observations of
+two exceptionally long bursts (so-called superbursts) allowed for the first
+time for the direct and the reflected burst flux to each be measured, as
+opposed to just their sum. The ratio of the reflected and direct flux (the
+reflection fraction) was much higher than what the anisotropies of a flat disk
+can account for. We create numerical models to calculate the anisotropy factors
+for different disk shapes, including concave disks. We present the anisotropy
+factors of the direct and reflected burst flux separately, as well as the
+anisotropy of the persistent flux. Reflection fractions substantially larger
+than unity are produced in case the inner accretion disk steeply increases in
+height, such that part of the star is blocked from view. Such a geometry could
+possibly be induced by the X-ray burst, if X-ray heating causes the inner disk
+to puff up.",1512.02889v2
+2017-06-25,"Magnetic anisotropy of $L1_0$-ordered FePt thin films studied by Fe and Pt $L_{2,3}$-edges x-ray magnetic circular dichroism","The strong perpendicular magnetic anisotropy of $L{\rm1_0}$-ordered FePt has
+been the subject of extensive studies for a long time. However, it is not known
+which element, Fe or Pt, mainly contributes to the magnetic anisotropy energy
+(MAE). We have investigated the anisotropy of the orbital magnetic moments of
+Fe 3$d$ and Pt 5$d$ electrons in $L{\rm1_0}$-ordered FePt thin films by Fe and
+Pt $L_{2,3}$-edge x-ray magnetic circular dichroism (XMCD) measurements for
+samples with various degrees of long-range chemical order $S$. Fe
+$L_{2,3}$-edge XMCD showed that the orbital magnetic moment was larger when the
+magnetic field was applied perpendicular to the film than parallel to it, and
+that the anisotropy of the orbital magnetic moment increased with $S$. Pt
+$L_{2,3}$-edge XMCD also showed that the orbital magnetic moment was smaller
+when the magnetic field was applied perpendicular to the film than parallel to
+it, opposite to the Fe $L_{2,3}$-edge XMCD results although the anisotropy of
+the orbital magnetic moment increases with $S$ like the Fe edge. These results
+are qualitatively consistent with the first-principles calculation by Solovyev
+${\it et\ al.}$ [Phys. Rev. B $\bf{52}$, 13419 (1995).], which also predicts
+the dominant contributions of Pt 5$d$ to the magnetic anisotropy energy rather
+than Fe 3$d$ due to the strong spin-orbit coupling and the small spin splitting
+of the Pt 5$d$ bands in $L{\rm1_0}$-ordered FePt.",1706.08183v1
+2017-07-18,HI anisotropies associated with radio-polarimetric filaments. Steep power spectra associated with cold gas,"LOFAR detected toward 3C 196 linear polarization structures which were found
+subsequently to be closely correlated with cold filamentary HI structures. The
+derived direction-dependent HI power spectra revealed marked anisotropies for
+narrow ranges in velocity, sharing the orientation of the magnetic field as
+expected for magneto hydrodynamical turbulence. Using the Galactic portion of
+the Effelsberg-Bonn HI Survey we continue our study of such anisotropies in the
+HI distribution in direction of two WSRT fields, Horologium and Auriga; both
+are well known for their prominent radio-polarimetric depolarization canals. At
+349 MHz the observed pattern in total intensity is insignificant but polarized
+intensity and polarization angle show prominent ubiquitous structures with so
+far unknown origin. Apodizing the HI survey data by applying a rotational
+symmetric 50 percent Tukey window, we derive average and position angle
+dependent power spectra. We fit power laws and characterize anisotropies in the
+power distribution. We use a Gaussian analysis to determine relative abundances
+for the cold and warm neutral medium. For the analyzed radio-polarimetric
+targets significant anisotropies are detected in the HI power spectra; their
+position angles are aligned to the prominent depolarization canals, initially
+detected by WSRT. HI anisotropies are associated with steep power spectra.
+Steep power spectra, associated with cold gas, are detected also in other
+fields. Radio-polarimetric depolarization canals are associated with
+filamentary HI structures that belong to the cold neutral medium (CNM).
+Anisotropies in the CNM are in this case linked to a steepening of the
+power-spectrum spectral index, indicating that phase transitions in a turbulent
+medium occur on all scales. Filamentary HI structures, driven by thermal
+instabilities, and radio-polarimetric filaments are associated with each other.",1707.05672v2
+2018-04-29,Stress anisotropy in shear-jammed packings of frictionless disks,"We perform computational studies of repulsive, frictionless disks to
+investigate the development of stress anisotropy in mechanically stable (MS)
+packings. We focus on two protocols for generating MS packings: 1) isotropic
+compression and 2) applied simple or pure shear strain $\gamma$ at fixed
+packing fraction $\phi$. MS packings of frictionless disks occur as geometric
+families (i.e. parabolic segments with positive curvature) in the
+$\phi$-$\gamma$ plane. MS packings from protocol 1 populate parabolic segments
+with both signs of the slope, $d\phi/d\gamma >0$ and $d\phi/d\gamma <0$. In
+contrast, MS packings from protocol 2 populate segments with $d\phi/d\gamma <0$
+only. For both simple and pure shear, we derive a relationship between the
+stress anisotropy and dilatancy $d\phi/d\gamma$ obeyed by MS packings along
+geometrical families. We show that for MS packings prepared using isotropic
+compression, the stress anisotropy distribution is Gaussian centered at zero
+with a standard deviation that decreases with increasing system size. For shear
+jammed MS packings, the stress anisotropy distribution is a convolution of
+Weibull distributions that depend on strain, which has a nonzero average and
+standard deviation in the large-system limit. We also develop a framework to
+calculate the stress anisotropy distribution for packings generated via
+protocol 2 in terms of the stress anisotropy distribution for packings
+generated via protocol 1. These results emphasize that for repulsive
+frictionless disks, different packing-generation protocols give rise to
+different MS packing probabilities, which lead to differences in macroscopic
+properties of MS packings.",1804.10962v2
+2018-06-21,"The electrical conductivity tensor of $β$-Ga2O3 analyzed by van der Pauw measurements: Inherent anisotropy, off-diagonal element, and the impact of grain boundaries","The semiconducting oxide $\beta$-Gallium Oxide ($\beta$-Ga$_{2}$O$_{3}$)
+possesses a monoclinic unit cell whose low symmetry generally leads to
+anisotropic physical properties. For example, its electrical conductivity is
+generally described by a polar symmetrical tensor of second rank consisting of
+four independent components. Using van der Pauw measurements in a well-defined
+square geometry on differently-oriented high-quality bulk samples and the
+comparison to finite element simulations we precisely determine the ratio of
+all elements of the $\beta$-Ga$_{2}$O$_{3}$ 3-dimensional electrical
+conductivity tensor. Despite the structural anisotropy a nearly isotropic
+conductivity at and above room temperature was found with the principal
+conductivities deviating from each other by less than 6% and the off-diagonal
+element being $\approx3$% of the diagonal ones. Analysis of the temperature
+dependence of the anisotropy and mobility of differently doped samples allows
+us to compare the anisotropy for dominant phonon-scattering to that for
+dominant ionized-impurity scattering. For both scattering mechanisms, the
+conductivites along the $a$ and $b$-direction agree within 2%. In contrast, the
+conductivity along $c$-direction amounts to $0.96\times$ and up to $1.12\times$
+that along the $b$-direction for phonon and ionized impurity scattering,
+respectively. The determined transport anisotropies are larger than the
+theoretically predicted effective mass anisotropy, suggesting slightly
+anisotropic scattering mechanisms. We demonstrate that significantly higher
+anisotropies can be caused by oriented extended structural defects in the form
+of low-angle grain boundaries for which we determined energy barriers of
+multiple 10 meV.",1806.08162v2
+2018-12-19,"Stress-induced anisotropy in granular materials: fabric, stiffness, and permeability","The loading of a granular material induces anisotropies of the particle
+arrangement (fabric) and of the material's strength, incremental stiffness, and
+permeability. Thirteen measures of fabric anisotropy are developed, which are
+arranged in four categories: as preferred orientations of the particle bodies,
+the particle surfaces, the contact normals, and the void space. Anisotropy of
+the voids is described through image analysis and with Minkowski tensors. The
+thirteen measures of anisotropy change during loading, as determined with
+three-dimensional discrete element simulations of biaxial plane strain
+compression with constant mean stress. Assemblies with four different particle
+shapes were simulated. The measures of contact orientation are the most
+responsive to loading, and they change greatly at small strains, whereas the
+other measures lag the loading process and continue to change beyond the state
+of peak stress and even after the deviatoric stress has nearly reached a steady
+state. The paper implements a methodology for characterizing the incremental
+stiffness of a granular assembly during biaxial loading, with orthotropic
+loading increments that preserve the principal axes of the fabric and stiffness
+tensors. The linear part of the hypoplastic tangential stiffness is monitored
+with oedometric loading increments. This stiffness increases in the direction
+of the initial compressive loading but decreases in the direction of extension.
+Anisotropy of this stiffness is closely correlated with a particular measure of
+the contact fabric. Permeabilities are measured in three directions with
+lattice Boltzmann methods at various stages of loading and for assemblies with
+four particle shapes. Effective permeability is negatively correlated with the
+directional mean free path and is positively correlated with pore width.",1812.08267v1
+2019-09-30,Simultaneous individual and dipolar collective properties in binary assemblies of magnetic nanoparticles,"Applications based on aggregates of magnetic nanoparticles are becoming
+increasingly widespread, ranging from hyperthermia to magnetic recording.
+However, although some uses require a collective behavior, other need a more
+individual-like response, the conditions leading to either of these behaviors
+are still poorly understood. Here we use nanoscale-uniform binary random dense
+mixtures with different proportions of oxide magnetic nanoparticles with
+low$/$high anisotropy as a valuable tool to explore the crossover from
+individual to collective behavior. Two different anisotropy scenarios have been
+studied in two series of binary compacts: M1, comprising maghemite
+($\gamma$-Fe$_2$O$_3$) nanoparticles of different sizes (9.0 nm $/$ 11.5 nm)
+with barely a factor of 2 between their anisotropy energies and M2, mixing
+equally-sized pure maghemite (low-anisotropy) and Co-doped maghemite
+(high-anisotropy) nanoparticles with a large difference in anisotropy energy
+(ratio $>$ 8). Interestingly, while the M1 series exhibits collective behavior
+typical of strongly-coupled dipolar systems, the M2 series presents a more
+complex scenario where different magnetic properties resemble either
+""individual-like"" or ""collective"", crucially emphasizing that the collective
+character must be ascribed to specific properties and not to the system as a
+whole. The strong differences between the two series, offer new insight
+(systematically ratified by simulations) into the subtle interplay between
+dipolar interactions, local anisotropy and sample heterogeneity, to determine
+the behavior of dense assemblies of magnetic nanoparticles.",1909.13500v1
+2020-05-12,"Constraints on the assembly history of the Milky Way's smooth, diffuse stellar halo from the metallicity-dependent, radially-dominated velocity anisotropy profiles probed with K giants and BHB stars using LAMOST, SDSS/SEGUE, and Gaia","We analyze the anisotropy profile of the Milky Way's smooth, diffuse stellar
+halo using SDSS/SEGUE blue horizontal branch stars and SDSS/SEGUE and LAMOST K
+giants. These intrinsically luminous stars allow us to probe the halo to
+approximately 100 kpc from the Galactic center. Line-of-sight velocities,
+distances, metallicities, and proper motions are available for all stars via
+SDSS/SEGUE, LAMOST, and Gaia, and we use these data to construct a full 7D set
+consisting of positions, space motions, and metallicity. We remove substructure
+from our samples using integrals of motion based on the method of Xue et al. We
+find radially dominated kinematic profiles with nearly constant anisotropy
+within 20 kpc, beyond which the anisotropy profile gently declines although
+remains radially dominated to the furthest extents of our sample. Independent
+of star type or substructure removal, the anisotropy depends on metallicity,
+such that the orbits of the stars become less radial with decreasing
+metallicity. For $-1.7<$ [Fe/H] $<-1$, the smooth, diffuse halo anisotropy
+profile begins to decline at Galactocentric distances $\sim20$ kpc, from
+$\beta\sim0.9$ to 0.7 for K giants and from $\beta\sim0.8$ to 0.1 for blue
+horizontal branch stars. For [Fe/H] $<-1.7$, the smooth, diffuse halo
+anisotropy remains constant along all distances with $0.2<\beta<0.7$ depending
+on the metallicity range probed, although independent on star type. These
+samples are ideal for estimating the total Galactic mass as they represent the
+virialized stellar halo system.",2005.05980v2
+2020-06-18,Interplay of Turbulence and Proton-Microinstability Growth in Space Plasmas,"Numerous prior studies have shown that as proton beta increases, a narrower
+range of proton temperature anisotropy values is observed. This effect has
+often been ascribed to the actions of kinetic microinstabilities because the
+distribution of observational data aligns with contours of constant instability
+growth rates in the beta-anisotropy plane. However, the linear Vlasov theory of
+instabilities assumes a uniform background in which perturbations grow. The
+established success of linear-microinstability theories suggests that the
+conditions in regions of extreme temperature anisotropy may remain uniform for
+a long enough time so that the instabilities have the chance to grow to
+sufficient amplitude. Turbulence, on the other hand, is intrinsically
+non-uniform and non-linear. Thin current sheets and other coherent structures
+generated in a turbulent plasma, may destroy the uniformity fast enough. It is
+therefore not a-priori obvious whether the presence of intermittency and
+coherent structures favors or disfavors instabilities. To address this
+question, we examined the statistical distribution of growth rates associated
+with proton temperature-anisotropy driven microinstabilities and local
+nonlinear time scales in turbulent plasmas. Linear growth rates are, on
+average, substantially less than the local nonlinear rates. However, at the
+regions of extreme values of temperature anisotropy, near the ""edges"" of the
+populated part of the proton temperature anisotropy-parallel beta plane, the
+instability growth rates are comparable or faster than the turbulence time
+scales. These results provide a possible answer to the question as to why the
+linear theory appears to work in limiting plasma excursions in anisotropy and
+plasma beta.",2006.10316v2
+2020-09-02,3D modeling from the onset of the SN to the full-fledged SNR: Role of an initial ejecta anisotropy on matter mixing,"The aim of this work is to bridge the gap between CC SNe and their remnants
+by investigating how post-explosion anisotropies in the ejecta influence the
+structure and chemical properties of the remnant at later times. We performed
+three-dimensional magneto-hydrodynamical simulations starting soon after the SN
+event and following the evolution of the system in the circumstellar medium
+(consisting of the wind of the stellar progenitor), for 5000 years, obtaining
+the physical scenario of a SNR. Here we focused the analysis on the case of a
+progenitor red supergiant of 19.8 M_sun. We also investigated how a
+post-explosion large-scale anisotropy in the SN affects the ejecta distribution
+and the matter mixing of heavy elements in the remnant, during the first 5000
+years of evolution. In the case of a spherically symmetric SN explosion without
+large-scale anisotropies, the remnant roughly keeps memory of the original
+onion-like layering of ejecta soon after the SN event. Nevertheless, as the
+reverse shock hits the ejecta, the element distribution departs from a
+homologous expansion, because of the slowing down of the outermost ejecta
+layers due to interaction with the reverse shock. In the case of a large-scale
+anisotropy developed after the SN, we found that the chemical stratification in
+the ejecta can be strongly modified and the original onion-like layering is not
+preserved. The anisotropy may cause spatial inversion of ejecta layers, for
+instance leading to Fe/Si-rich ejecta outside the O shell, and may determine
+the formation of Fe/Si-rich jet-like features that may protrude the remnant
+outline. The level of matter mixing and the properties of the jet-like feature
+are sensitive to the initial physical (density and velocity) and geometrical
+(size and position) initial characteristics of the anisotropy.",2009.01157v1
+2020-11-04,Unveiling temperature dependence mechanisms of perpendicular magnetic anisotropy at Fe/MgO interfaces,"The perpendicular magnetic anisotropy (PMA) at magnetic transition
+metal/oxide interfaces is a key element in building out-of-plane magnetized
+magnetic tunnel junctions for spin-transfer-torque magnetic random access
+memory (STT-MRAM). Size downscaling renders magnetic properties more sensitive
+to thermal effects. Thus, understanding the temperature dependence of the
+magnetic anisotropy is crucial. In this work, we theoretically address the
+correlation between temperature dependence of PMA and magnetization in typical
+Fe/MgO-based structures. In particular, the possible mechanisms behind the
+experiments reporting deviations from the Callen and Callen scaling power law
+are analyzed. At ideal interfaces, first-principles calculations reveal (i)
+small high-order anisotropy constants compared to first order and (ii) enhanced
+exchange constants. Considering these two intrinsic effects in the atomistic
+simulations, the temperature-dependence of the total and layer-resolved
+anisotropy are found to follow the Callen and Callen scaling power law, thus
+ruling out an intrinsic microscopic mechanism underlying deviations from this
+law. Besides, two possible extrinsic macroscopic mechanisms are unveiled namely
+the influence of the dead layer, often present in the storage layer of STT-MRAM
+cells, and the spatial inhomogeneities of the interfacial magnetic anisotropy.
+About the first mechanism, we show that the presence of a dead layer tends to
+reduce the scaling exponents. In the second mechanism, increasing the
+percentage of inhomogeneity in the interfacial PMA is revealed to decrease the
+scaling exponent. These results allow us to explain the difference in scaling
+exponents relating anisotropy and magnetization thermal variations reported in
+earlier experiments. This is crucial for the understanding of the thermal
+stability of the storage layer magnetization in STT-MRAM applications.",2011.02220v3
+2021-05-21,Comparative study of superconducting and normal-state anisotropy in Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$ superconductors with controlled amounts of interstitial excess Fe,"We report a systematic study of the superconducting (SC) and normal-state
+anisotropy of Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$ single crystals with controlled
+amounts of excess Fe ($y$ = 0, 0.07, and 0.14). The SC state anisotropy
+$\gamma_{H}$ was obtained by measuring the upper critical fields under high
+magnetic fields over 50 T for both $H\parallel ab$ and $H\parallel c$. On the
+other hand, the normal state anisotropy $\gamma_{\rho}$ was obtained by
+measuring the resistivity with current flowing in the $ab$ plane ($\rho_{ab}$)
+and along the $c$ axis ($\rho_c$). To precisely measure $\rho_{ab}$ and
+$\rho_c$ in the same part of a specimen avoiding the variation dependent on
+pieces or parts, we adopt a new method using a micro-fabricated bridge with an
+additional neck part along $c$ axis. The $\gamma_{H}$ decreases from a value
+dependent on the amount of excess Fe at $T_{\rm{c}}$ to a common value $\sim$ 1
+at 2 K. The different $\gamma_{H}$ at $T_{\rm{c}}$ ($\sim$1.5 for $y$ = 0, and
+2.5 for $y$ = 0.14) suggests that the anisotropy of effective mass
+$m_c^*/m_{ab}^*$ increases from $\sim$ 2.25 ($y$ = 0) to 6.25 ($y$ = 0.14) with
+the excess Fe. The almost isotropic $\gamma_{H}$ at low temperatures is due to
+the strong spin paramagnetic effect at $H\parallel ab$. By contrast, the
+$\gamma_{\rho}$ shows a much larger value of $\sim$ 17 ($y$ = 0) to $\sim$ 50
+($y$ = 0.14) at the temperature just above $T_{\rm{c}}$. Combined the results
+of $\gamma_{H}$ and $\gamma_{\rho}$ near $T_{\rm{c}}$, we found out that the
+discrepant anisotropies between the SC and normal states originates from a
+large anisotropy of scattering time $\tau_{ab}$/$\tau_c$ $\sim$ 7.8. The
+$\tau_{ab}$/$\tau_c$ is found to be independent of the excess Fe.",2105.10093v1
+2021-08-10,Spin-excitation anisotropy in the nematic state of detwinned FeSe,"The origin of the electronic nematicity in FeSe is one of the most important
+unresolved puzzles in the study of iron-based superconductors. In both spin-
+and orbital-nematic models, the intrinsic magnetic excitations at
+$\mathbf{Q}_1=(1, 0)$ and $\mathbf{Q}_2=(0, 1)$ of twin-free FeSe are expected
+to provide decisive criteria for clarifying this issue. Although a
+spin-fluctuation anisotropy below 10 meV between $\mathbf{Q}_1$ and
+$\mathbf{Q}_2$ has been observed by inelastic neutron scattering around
+$T_c\sim 9$ K ($<<T_s\sim 90$ K), it remains unclear whether such an anisotropy
+also persists at higher energies and associates with the nematic transition
+$T_{\rm s}$. Here we use resonant inelastic x-ray scattering (RIXS) to probe
+the high-energy magnetic excitations of uniaxial-strain detwinned FeSe and
+{\BFA}. A prominent anisotropy between the magnetic excitations along the $H$
+and $K$ directions is found to persist to $\sim200$ meV in FeSe, which is even
+more pronounced than the anisotropy of spin waves in {\BFA}. This anisotropy
+decreases gradually with increasing temperature and finally vanishes at a
+temperature around the nematic transition temperature $T_{\rm s}$. Our results
+reveal an unprecedented strong spin-excitation anisotropy with a large energy
+scale well above the $d_{xz}/d_{yz}$ orbital splitting, suggesting that the
+nematic phase transition is primarily spin-driven. Moreover, the measured
+high-energy spin excitations are dispersive and underdamped, which can be
+understood from a local-moment perspective. Our findings provide the
+much-needed understanding of the mechanism for the nematicity of FeSe and
+points to a unified description of the correlation physics across seemingly
+distinct classes of Fe-based superconductors.",2108.04484v2
+2021-10-20,What can be learnt from UHECR anisotropies observations? Paper I : large-scale anisotropies and composition features,"We investigate the implications of the current data regarding large scale
+anisotropies, and examine to what extent they can be used to constrain the
+origin of UHECRs and the astrophysical parameters of the source scenarios. We
+discuss the possibility of observing an associated anisotropy of the
+composition, the potential benefit of the separation of the different nuclear
+components and the interest of observing the UHECR sky with larger exposure
+future observatories. We simulate UHECR sky maps for various astrophysical
+scenarios satisfying the current observational constraints, taking into account
+the energy losses of the UHE protons and nuclei and their deflections by
+intervening magnetic fields. We investigate scenarios in which the UHECR source
+distribution follows that of the galaxies, varying the source composition and
+spectrum, the source density and the magnetic field models. We apply similar
+analyses as those used by the Auger collaboration. We find that: i) reproducing
+the observed dipole anisotropy and its energy evolution is relatively easy
+within our assumptions; ii) this agreement can be obtained with different sets
+of assumptions on the astrophysical parameters, and is thus not, at this stage,
+very constraining for UHECR source scenarios; iii) the actual reconstructed
+direction of the dipole appears non natural in essentially all scenarios
+investigated, and challenges their main assumptions on the source distribution
+or the assumed magnetic field configuration, especially in the Galaxy; iv)
+except for protons, the energy range in which the GZK horizon strongly reduces
+is a key target for anisotropy searches for each given nuclear species; v) The
+composition anisotropy naturally expected in our models is unlikely to account
+for that recently reported by Auger unless the observed amplitude is a strong
+positive statistical fluctuation of an intrinsically weaker signal.",2110.10761v1
+1994-03-18,Anisotropies of the Cosmic Background Radiation in a Reionized Universe,"We trace the evolution of cosmic microwave background photons propagating
+through a reionized model universe. The reionization of the intergalactic
+medium is achieved by UV photons emitted from the decaying `hot' dark matter
+neutrinos. The model universe is represented by a comoving cube through which
+we propagate photons and subject them to the Sachs-Wolfe effect and Thomson
+scattering off the ionized fraction of the IGM, beginning at z=1900 until the
+present z=0. The simulation follows the evolving matter inhomogeneities and
+microwave background photons into the present nonlinear regime and yields
+temperature maps of the microwave sky as a comoving observer would detect. Our
+temperature maps display anisotropies on scales ranging from 2 to 8 degrees
+with rms amplitudes ranging from DT/T_{rms} =2.8 to 3.4 times 10^{-5} without
+reionization. If we allow the neutrinos to decay and subsequently reionize the
+IGM, the level of the temperature anisotropies is reduced to DT/T=0.8 to 1.1
+times 10^{-5}. This includes the Doppler shifts suffered by the CMB photons as
+they scatter off the moving ionized fraction of the IGM. If, however,
+reionization is caused by a late and sudden energy input into the IGM, we find
+that some reduction in $\Delta T/T$ occurs, but not enough to make this
+scenario consistent with observations. We find that the decaying neutrino
+hypothesis is more efficient at reducing primordial anisotropies and generates
+smaller Doppler anisotropies than a model reionized via a late and sudden
+energy input into the IGM.",9403040v1
+1997-02-03,Microwave Background Anisotropies from Scaling Seed Perturbations,"We study microwave background anisotropies induced by scaling seed
+perturbations in a universe dominated by cold dark matter. Using a gauge
+invariant linear perturbation analysis, we solve the perturbation equations on
+super-horizon scales, for CMB anisotropies triggered by generic gravitational
+seeds. We find that perturbations induced by seeds --- under very mild
+restrictions --- are nearly isocurvature. Thus, compensation, which is mainly
+the consequence of physically sensible initial conditions, is very generic.
+  We then restrict our study to the case of scaling sources, motivated by
+global scalar fields. We parameterize the energy momentum tensor of the source
+by ``seed functions'' and calculate the Sachs-Wolfe and acoustic contributions
+to the CMB anisotropies. We discuss the dependence of the anisotropy spectrum
+on the parameters of the model considered. Even within the restricted class of
+models investigated in this work, we find a surprising variety of results for
+the position and height of the first acoustic peak as well as for the overall
+amplitude. In particular, for certain choices of parameters, the spectrum
+resembles very much the well known adiabatic inflationary spectrum, whereas for
+others, the position of the first acoustic peak is significantly shifted
+towards smaller angular scales.",9702028v4
+1997-05-07,Detection of Cosmic Microwave Background Anisotropy by the Third Flight of MSAM,"The third flight of the Medium Scale Anisotropy Measurement (MSAM1), in June
+1995, observed a new strip of sky, doubling the sky coverage of the original
+MSAM1 dataset. MSAM1 observes with a 0.5 deg beam size in four bands from 5-20
+icm. From these four bands we derive measurements of cosmic microwave
+background radiation (CMBR) anisotropy and interstellar dust emission. Our
+measurement of dust emission correlates well with the 100 um IRAS Sky Survey
+Atlas; from this comparison we determine an effective emissivity spectral index
+between 100 um and 444 um of 1.46 +/- 0.28. Analysis of our measurement of CMBR
+anisotropy shows that for Gaussian-shaped correlation functions with theta_c =
+0.3 deg, we place a limit on total rms anisotropy of 2.2 x 10^{-5} < Delta T/T
+< 3.9 x 10^{-5} (90% confidence interval, including calibration error). The
+band-power limits are <delta T> = <l (l+1)C_l/2 pi>^{1/2} = 50^{+16}_{-11} uK
+at l = 160, and <delta T> = 65^{+18}_{-13} uK at l = 270 (1 sigma limits,
+including calibration error). The corresponding limits with statistical errors
+only are <delta T> = 50^{+13}_{-9} uK and <delta T> = 65^{+14}_{-10} uK
+respectively. These measurements are consistent with a standard adiabatic cold
+dark matter model; we discuss constraints on h, n, and the redshift of
+reionization.",9705041v2
+1997-11-04,Recent developments in the calculation of CMB anisotropies,"We discuss three recent developments in the calculation of CMB anisotropies.
+First, we consider relativistic corrections to the Sunyaev-Zel'dovich effect.
+By extending the Kompaneets equation to the relativistic domain we are able to
+derive simple analytic forms for the SZ spectral distortion. Second, we discuss
+covariant kinetic theory methods for the gauge-invariant calculation of CMB
+anisotropies. We present a covariant version of the Boltzmann equation which we
+use to derive covariant and gauge-invariant equations describing a CDM model,
+which are independent of background curvature and type of perturbation (scalar,
+vector or tensor). By integrating the covariant Boltzmann equation along the
+line of sight, and using the instantaneous recombination approximation, we
+obtain an expression for the large-scale anisotropy which agrees with an
+expression derived recently by Dunsby. Third, we discuss recent accurate
+calculations of the CMB anisotropy in global defect models of cosmic structure
+formation. In such models the effects of vector modes are significant and when
+combined with the effects of decoherence lead to a suppression of the Doppler
+peaks. The result is that global defect models may already be at variance with
+the growing volume of CMB and large scale structure data.",9711028v3
+1997-11-10,Sub-degree CMB anisotropies from inflationary bubbles,"It is well known that processes of first order phase transitions may have
+occurred in the inflationary era. If one or more occurred well before the end
+of inflation, the nucleated bubbles are stretched to large scales and the
+primordial power spectrum contains a scale dependent non-Gaussian component
+provided by the remnants of the bubbles. We predict the anisotropies in the
+cosmic microwave background (CMB) induced by inflationary bubbles. We build a
+general analytic model for describing a bubbly perturbation; we evolve each
+Fourier mode using the linear theory of perturbations from reheating until
+decoupling; we get the CMB anisotropies by considering the bubbly perturbation
+intersecting the last scattering surface. The CMB image of an inflationary
+bubble is a series of concentric isothermal rings of different color (sign of
+$\delta T/T$) on the scale of the sound horizon at decoupling ($\le 1^{o}$ in
+the sky); the resulting anisotropy is therefore strongly non-Gaussian. The mean
+amplitude of $\delta T/T$ for a bubble of size $L$ follows the known estimates
+for linear perturbations, $\delta T/T\simeq\delta\rho /\rho\cdot
+(L/H^{-1})^{2}$. In particular, bubbles with size corresponding to the seeds of
+the observed large scale voids (tens of comoving Mpc) induce an interesting
+pattern of CMB anisotropies on the sub-degree angular scale, to be further
+investigated and compared with the forthcoming high resolution CMB maps
+provided by the MAP and the Planck experiments.",9711095v1
+1998-06-17,Gravothermal Catastrophe in Anisotropic Spherical Systems,"In this paper we investigate the gravothermal instability of spherical
+stellar systems endowed with a radially anisotropic velocity distribution. We
+focus our attention on the effects of anisotropy on the conditions for the
+onset of the instability and in particular we study the dependence of the
+spatial structure of critical models on the amount of anisotropy present in a
+system. The investigation has been carried out by the method of linear series
+which has already been used in the past to study the gravothermal instability
+of isotropic systems.
+  We consider models described by King, Wilson and Woolley-Dickens distribution
+functions. In the case of King and Woolley-Dickens models, our results show
+that, for quite a wide range of amount of anisotropy in the system, the
+critical value of the concentration of the system (defined as the ratio of the
+tidal to the King core radius of the system) is approximately constant and
+equal to the corresponding value for isotropic systems. Only for very
+anisotropic systems the critical value of the concentration starts to change
+and it decreases significantly as the anisotropy increases and penetrates the
+inner parts of the system. For Wilson models the decrease of the concentration
+of critical models is preceded by an intermediate regime in which critical
+concentration increases, it reaches a maximum and then it starts to decrease.
+The critical value of the central potential always decreases as the anisotropy
+increases.",9806233v2
+1999-03-17,The Standard Cosmological Model and CMB Anisotropies,"This is a course on cosmic microwave background (CMB) anisotropies in the
+standard cosmological model, designed for beginning graduate students and
+advanced undergraduates. ``Standard cosmological model'' in this context means
+a Universe dominated by some form of cold dark matter (CDM) with adiabatic
+perturbations generated at some initial epoch, e.g., Inflation, and left to
+evolve under gravity alone (which distinguishes it from defect models). The
+course is primarily theoretical and concerned with the physics of CMB
+anisotropies in this context and their relation to structure formation. Brief
+presentations of the uniform Big Bang model and of the observed large--scale
+structure of the Universe are given. The bulk of the course then focuses on the
+evolution of small perturbations to the uniform model and on the generation of
+temperature anisotropies in the CMB. The theoretical development is performed
+in the (pseudo--)Newtonian gauge because it aids intuitive understanding by
+providing a quick reference to classical (Newtonian) concepts. The fundamental
+goal of the course is not to arrive at a highly exact nor exhaustive
+calculation of the anisotropies, but rather to a good understanding of the
+basic physics that goes into such calculations.",9903260v1
+1999-05-11,Searching for the non-gaussian signature of the CMB secondary anisotropies,"In a first paper (Forni & Aghanim 1999), we developed several statistical
+discriminators to test the non-gaussian nature of a signal. These tests are
+based on the study of the coefficients in a wavelet decomposition basis. In
+this paper, we apply them in a cosmological context, to the study of the nature
+of the Cosmic Microwave Background (CMB) anisotropies. The latter represent the
+superposition of primary anisotropy imprints of the initial density
+perturbations and secondary ones due to photon interactions after
+recombination. In an inflationary scenario (standard Cold Dark Matter) with
+gaussian distributed fluctuations, we study the statistical signature of the
+secondary effects. More specifically, we investigate the dominant effects
+arising from the Compton scattering of CMB photons in ionised regions of the
+Universe: the Sunyaev-Zel'dovich effect of galaxy clusters and the effects of a
+spatially inhomogeneous re-ionisation of the Universe. Our study specifies and
+predicts the non-gaussian signature of the secondary anisotropies induced by
+these scattering effects. We find that our statistical discriminators allow us
+to distinguish and highlight the non-gaussian signature of a process even if it
+is combined with a larger gaussian one. We investigate the detectability of the
+secondary anisotropy non-gaussian signature in the context of the future CMB
+satellites (MAP and Planck Surveyor).",9905124v1
+1999-06-03,The Anisotropy of Cosmic Ray Arrival Direction around 10^18eV,"Anisotropy in the arrival directions of cosmic rays around 10^{18}eV is
+studied using data from the Akeno 20 km^2 array and the Akeno Giant Air Shower
+Array (AGASA), using a total of about 216,000 showers observed over 15 years
+above 10^{17}eV. In the first harmonic analysis, we have found significant
+anisotropy of $\sim$ 4 % around 10^{18}eV, corresponding to a chance
+probability of $\sim 10^{-5}$ after taking the number of independent trials
+into account. With two dimensional analysis in right ascension and declination,
+this anisotropy is interpreted as an excess of showers near the directions of
+the Galactic Center and the Cygnus region. This is a clear evidence for the
+existence of the galactic cosmic ray up to the energy of 10^{18}eV. Primary
+particle which contribute this anisotropy may be proton or neutron.",9906056v1
+1999-07-08,Reionization Revisited: Secondary CMB Anisotropies and Polarization,"Secondary CMB anisotropies and polarization provide a laboratory to study
+structure formation in the reionized epoch. We consider the kinetic
+Sunyaev-Zel'dovich effect from mildly nonlinear large-scale structure and show
+that it is a natural extension of the perturbative Vishniac effect. If the gas
+traces the dark matter to overdensities of order 10, as expected from
+simulations, this effect is at least comparable to the Vishniac effect at
+arcminute scales. On smaller scales, it may be used to study the thermal
+history-dependent clustering of the gas. Polarization is generated through
+Thomson scattering of primordial quadrupole anisotropies, kinetic (second order
+Doppler) quadrupole anisotropies and intrinsic scattering quadrupole
+anisotropies. Small scale polarization results from the density and ionization
+modulation of these sources. These effects generically produce comparable E and
+B-parity polarization, but of negligible amplitude (0.001-0.01 uK) in adiabatic
+CDM models. However, the primordial and kinetic quadrupoles are observationally
+comparable today so that a null detection of B-polarization would set
+constraints on the evolution and coherence of the velocity field. Conversely, a
+detection of a cosmological B-polarization even at large angles does not
+necessarily imply the presence of gravity waves or vorticity. For these
+calculations, we develop an all-sky generalization of the Limber equation that
+allows for an arbitrary local angular dependence of the source for both scalar
+and symmetric trace-free tensor fields on the sky.",9907103v2
+2000-05-08,MAXIMA-1: A Measurement of the Cosmic Microwave Background Anisotropy on angular scales of 10 arcminutes to 5 degrees,"We present a map and an angular power spectrum of the anisotropy of the
+cosmic microwave background (CMB) from the first flight of MAXIMA. MAXIMA is a
+balloon-borne experiment with an array of 16 bolometric photometers operated at
+100 mK. MAXIMA observed a 124 square degrees region of the sky with 10
+arcminute resolution at frequencies of 150, 240 and 410 GHz. The data were
+calibrated using in-flight measurements of the CMB dipole anisotropy. A map of
+the CMB anisotropy was produced from three 150 and one 240 GHz photometer
+without need for foreground subtractions. Analysis of this CMB map yields a
+power spectrum for the CMB anisotropy over the range 36 < l < 785. The spectrum
+shows a peak with an amplitude of 78 +/- 6 micro-Kelvin at l ~ 220 and an
+amplitude varying between ~40 micro-Kelvin and ~50 micro-Kelvin for 400 < l <
+785.",0005123v3
+2001-02-15,Binned Cosmic Microwave Background Anisotropy Power Spectra: Peak Location,"We use weighted mean and median statistics techniques to combine individual
+cosmic microwave background (CMB) anisotropy detections and determine binned,
+multipole-space, CMB anisotropy power spectra. The resultant power spectra are
+peaked. The derived weighted-mean CMB anisotropy power spectrum is not a good
+representation of the individual measurements in a number of multipole-space
+bins, if the CMB anisotropy is Gaussian and correlations between individual
+measurements are small. This could mean that some observational error bars are
+underestimated, possibly as a consequence of undetected systematic effects.
+Discarding the most discrepant 5% of the measurements alleviates but does not
+completely resolve this problem. The median-statistics power spectrum of this
+culled data set is not as constraining as the weighted-mean power spectrum.
+Nevertheless it indicates that there is more power at multipoles $\ell \sim
+150-250$ than is expected in an open cold dark matter (CDM) model, and it is
+more consistent with a flat CDM model. Unlike the weighted-mean power spectrum,
+the median-statistics power spectrum at $\ell \sim 400-500$ does not exclude a
+second peak in the flat CDM model.",0102264v1
+2002-12-12,High Resolution Observations of the CMB Power Spectrum with ACBAR,"We report the first measurements of anisotropy in the cosmic microwave
+background (CMB) radiation with the Arcminute Cosmology Bolometer Array
+Receiver (ACBAR). The instrument was installed on the 2.1m Viper telescope at
+the South Pole in January 2001; the data presented here are the product of
+observations up to and including July 2002. The two deep fields presented here,
+have had offsets removed by subtracting lead and trail observations and cover
+approximately 24 deg^2 of sky selected for low dust contrast. These results
+represent the highest signal to noise observations of CMB anisotropy to date;
+in the deepest 150GHz band map, we reached an RMS of 8.0\mu K per 5' beam. The
+3 degree extent of the maps, and small beamsize of the experiment allow the
+measurement of the CMB anisotropy power spectrum over the range \ell = 150-3000
+with resolution of \Delta \ell=150. The contributions of galactic dust and
+radio sources to the observed anisotropy are negligible and are removed in the
+analysis. The resulting power spectrum is found to be consistent with the
+primary anisotropy expected in a concordance \Lambda CDM Universe.",0212289v1
+2003-04-01,Decaying neutron propagation in the Galaxy and the Cosmic Ray anisotropy at 1 EeV,"We study the cosmic ray arrival distribution expected from a source of
+neutrons in the galactic center at energies around 1 EeV and compare it with
+the anisotropy detected by AGASA and SUGAR. Besides the point-like signal in
+the source direction produced by the direct neutrons, an extended signal due to
+the protons produced in neutron decays is expected. This associated proton
+signal also leads to an excess in the direction of the spiral arm. For
+realistic models of the regular and random galactic magnetic fields, the
+resulting anisotropy as a function of the energy is obtained. We find that for
+the anisotropy to become sufficiently suppressed below E\sim 10^{17.9}eV, a
+significant random magnetic field component is required, while on the other
+hand, this also tends to increase the angular spread of the associated proton
+signal and to reduce the excess in the spiral arm direction. The source
+luminosity required in order that the right ascension anisotropy be 4% for the
+AGASA angular exposure corresponds to a prediction for the point-like flux from
+direct neutrons compatible with the flux detected by SUGAR. We also analyse the
+distinguishing features predicted for a large statistics southern observatory.",0304023v2
+2003-05-09,Trade-off between angular resolution and straylight contamination in CMB anisotropy experiments. I. Pattern simulations,"The study of Cosmic Microwave Background (CMB) anisotropies represents one of
+the most powerful Cosmological tools. After the great success of the two NASA's
+satellite missions COBE and WMAP, Planck represents the third generation of
+mm-wave instruments designed for space observations of CMB anisotropies within
+the new Cosmic Vision 2020 ESA Science Programme. The Planck survey will cover
+the whole sky with unprecedented sensitivity, angular resolution and frequency
+coverage, using two instruments that share the focal region of a 1.5 m off-axis
+dual reflector telescope: the Low Frequency Instrument (LFI) and the High
+Frequency Instrument (HFI). Within the LFI optical interfaces optimisation
+activity, two concurrent demands have to be satisfied: the best angular
+resolution (which impacts the ability to reconstruct the anisotropy power
+spectrum of the CMB anisotropies at high multipoles) and the lowest level of
+straylight contamination (that may be one of the most critical sources of
+systematic effects). We present the results of the optical simulations aimed to
+establish the trade-off between angular resolution and straylight rejection,
+carried out for the 100 GHz channel of Planck Low Frequency Instrument. Antenna
+pattern of different models of dual profiled corrugated conical feed horns have
+been simulated using advanced simulation techniques, considering the whole
+spacecraft geometry in order to obtain truthful sidelobe predictions. Optical
+computation accuracy necessary to provide strong straylight evaluation in
+reasonable computational time is shown and the inadequacy of a Gaussian feed
+model in realistic far pattern predictions is demonstrated. This paper is based
+on LFI activities.",0305152v1
+2004-02-17,The origin and implications of dark matter anisotropic cosmic infall on ~L* haloes,"We measure the anisotropy of dark matter flows on small scales in the near
+environment of haloes using a large set of simulations. We rely on two
+different approaches to quantify the anisotropy of the cosmic infall: we
+measure the flows at the haloes' virial radius while describing the infalling
+matter via fluxes through a spherical shell; we measure the spatial and
+kinematical distributions of satellites and substructures around haloes
+detected by the subclump finder ADAPTAHOP first described in the appendix. The
+two methods are found to be in agreement both qualitatively and quantitatively
+via one and two points statistics.The infall takes place preferentially in the
+plane perpendicular to the direction defined by the halo's spin. We computed
+the excess of equatorial accretion both through rings and via a harmonic
+expansion of the infall. The level of anisotropy of infalling matter is found
+to be ~15 %. The substructures have their spin orthogonal to their velocity
+vector in the halo's rest frame at a level of about 5%, suggestive of an image
+of a flow along filamentary structures which provides an explanation for the
+measured anisotropy. We conclude that a halo does not see its environment as an
+isotropic perturbation, investigate how the anisotropy is propagated inwards
+using perturbation theory, and discuss briefly implications for weak lensing,
+warps and the thickness of galactic disks.",0402405v1
+2004-04-21,Statistical Significance of Small Scale Anisotropy in Arrival Directions of Ultra-High Energy Cosmic Rays,"Recently, the High Resolution Fly's Eye (HiRes) experiment claims that there
+is no small scale anisotropy in the arrival distribution of ultra-high energy
+cosmic rays (UHECRs) above $E>10^{19}$ eV contrary to the Akeno Giant Air
+Shower Array (AGASA) observation. In this paper, we discuss the statistical
+significance of this discrepancy between the two experiments. We calculate
+arrival distribution of UHECRs above $10^{19}$ eV predicted by the source
+models constructed using the Optical Redshift Survey galaxy sample. We apply
+the new method developed by us for calculating arrival distribution in the
+presence of the galactic magnetic field. The great advantage of this method is
+that it enables us to calculate UHECR arrival distribution with lower energy
+($\sim 10^{19}$ eV) than previous studies within reasonable time by following
+only the trajectories of UHECRs actually reaching the earth. It has been
+realized that the small scale anisotropy observed by the AGASA can be explained
+with the source number density $\sim 10^{-5 \sim -6}$ Mpc$^{-3}$ assuming weak
+extragalactic magnetic field ($B \le 1$ nG). We find that the predicted small
+scale anisotropy for this source number density is also consistent with the
+current HiRes data. We thus conclude that the statement by the HiRes experiment
+that they do not find small scale anisotropy in UHECR arrival distribution is
+not statistically significant at present. We also show future prospect of
+determining the source number density with increasing amount of observed data.",0404411v2
+2004-05-26,Cross-Correlation Studies between CMB Temperature Anisotropies and 21 cm Fluctuations,"During the transition from a neutral to a fully reionized universe,
+scattering of cosmic microwave background (CMB) photons via free-electrons
+leads to a new anisotropy contribution to the temperature distribution. If the
+reionization process is inhomogeneous and patchy, the era of reionization is
+also visible via brightness temperature fluctuations in the redshifted 21 cm
+line emission from neutral Hydrogen. Since regions containing electrons and
+neutral Hydrogen are expected to trace the same underlying density field, the
+two are (anti) correlated and this is expected to be reflected in the
+anisotropy maps via a correlation between arcminute-scale CMB temperature and
+the 21 cm background. In terms of the angular cross-power spectrum,
+unfortunately, this correlation is insignificant due to a geometric
+cancellation associated with second order CMB anisotropies. The same
+cross-correlation between ionized and neutral regions, however, can be studied
+using a bispectrum involving large scale velocity field of ionized regions from
+the Doppler effect, arcminute scale CMB anisotropies during reionization, and
+the 21 cm background. While the geometric cancellation is partly avoided, the
+signal-to-noise ratio related to this bispectrum is reduced due to the large
+cosmic variance related to velocity fluctuations traced by the Doppler effect.
+Unless the velocity field during reionization can be independently established,
+it is unlikely that the correlation information related to the relative
+distribution of ionized electrons and regions containing neutral Hydrogen can
+be obtained with a combined study involving CMB and 21 cm fluctuations.",0405528v1
+2005-04-27,"The Surprising Anisotropy of Fast Rotating, Disky Elliptical Galaxies","The projected kinematical properties of unequal-mass merger remnants of disk
+galaxies are analysed and shown to agree well with observations of disky, fast
+rotating elliptical galaxies. This supports the major merger hypothesis of
+early-type galaxy formation. However, in contrast to previous claims, the
+merger remnants are very anisotropic with values of the anisotropy parameter
+that are similar to equal-mass merger remnants that form boxy, slowly rotating
+ellipticals. Including gas in the simulations does not change this result
+although the line-of-sight velocity profile and the intrinsic orbital structure
+are strongly affected by the presenceof gas. The kinematical difference between
+boxy and disky ellipticals appears not to be the amount of anisotropy but
+rather rotation and the shape of the velocity dispersion tensor. The apparent
+isotropy of observed disky ellipticals is shown to result from inclination
+effects. Even small inclination angles strongly reduce the measured anisotropy
+of fast rotating systems, seen in projection. A second problem is the limited
+amount of information that is available when measuring only the central
+velocity dispersion and a characteristic rotation and ellipticity. Methods are
+investigated that allow a better determination of the intrinsic anisotropy of
+fast rotating early-type galaxies with known inclination angles.",0504595v1
+2005-08-08,The trail of discrete X-ray sources in the early-type galaxy NGC4261: anisotropy in the globular cluster distribution?,"Chandra images of the elliptical galaxy NGC4261 have revealed an anisotropy
+in the spatial distribution of the off-nuclear X-ray sources, interpreted by
+Zezas et al. as evidence of an association with a young stellar population. Our
+independent analysis of archive X-ray (Chandra) and optical (INT and HST)
+observations confirms the anisotropy of the X-ray sources but conducts to a
+different interpretation for their origin. We find that nearly half of the
+X-ray sources are associated to a globular cluster (optical counterpart)
+suggesting that they are accreting low-mass X-ray binaries. Where color index
+information is available, the X-ray sources are found to reside in red
+(metal-rich) systems. The luminosity function of the X-ray sources is also
+consistent with the one drawn from a population of Low Mass X-ray Binaries. We
+further investigate the properties of the sample of point-like sources obtained
+from archival optical images that we suggest are good globular cluster
+candidates and for which we find that the projected spatial distribution is
+non-homogeneous. In addition, we show that the distributions of the optical and
+X-ray populations are very similar, which leads us to conclude that the spatial
+anisotropy of the X-ray sources in NGC4261 is mostly a reflection of the
+anisotropy of the globular cluster population.",0508189v1
+2005-11-22,Mapping the large-scale anisotropy in the WMAP data,"Analyses of recent cosmic microwave background (CMB) observations have
+provided increasing indications for the existence of large scale anisotropy in
+the universe. Given the far reaching consequences of such an anisotropy for our
+understanding of the universe, it is important to employ alternative indicators
+in order to determine whether the reported anisotropy is cosmological in
+origin, and if so extract further information that may be helpful for
+identifying its causes. Here we propose a new directional indicator, based on
+angular-separation histograms of pairs of pixels with similar temperatures in
+the CMB map, which provides a measure of departure from statistical isotropy.
+The main advantage of this indicator is that it can be used to generate a sky
+map of large-scale anisotropies in the CMB temperature map, thus allowing a
+possible additional window into their causes. Using this indicator, we find a
+statistically significant (at 95% CL) preferred direction in the CMB data and
+discuss how it compares with other such axes recently reported. We also show
+that our findings are robust with respect to both the details of the method
+used, and the choice of the WMAP CMB maps employed, including the three-year
+CMB data released recently.",0511666v4
+2006-01-19,The Contribution of the Intergalactic Medium to Cosmic Microwave Background Anisotropies,"We compute the power spectrum of the Cosmic Microwave Background temperature
+anisotropies generated by the Intergalactic Medium. To estimate the electron
+pressure along the line of sight and its contribution to the Sunyaev-Zeldovich
+component of the CMB anisotropies, we assume the non-linear baryonic density
+contrast is well described by a log-normal distribution. For model parameters
+in agreement with observations and for an experiment operating in the
+Rayleigh-Jeans regime, the largest IGM contribution is expected at scales
+corresponding to multipole numbers of about 2000. The amplitude is rather
+uncertain and could be as large as 100-200 [mikroK]^2, comparable to the
+contribution of galaxy clusters. The actual value is strongly dependent on the
+gas polytropic index and the amplitude of the matter power spectrum sigma_8. At
+all redshifts, the largest contribution comes from scales very close to the
+comoving baryon Jeans length. This scale is not yet resolved in numerical
+simulations that follow the evolution of gas on cosmological scales. The
+anisotropy generated by the Intergalactic Medium could make compatible the
+excess of power measured by Cosmic Background Imager (CBI) on scales of l >
+2000 with sigma_8=0.9. Taking the CBI result as an upper limit, the polytropic
+index can be constrained to < 1.5 at 2-sigma level at redshifts z ~ 0.1-0.4.
+With its large frequency coverage, the PLANCK satellite will be able to measure
+the secondary anisotropies coming from hot gas. Cluster and Intergalactic
+Medium contributions could be separated by cross correlating galaxy/cluster
+catalogs with CMB maps. This measurement will determine the state of the gas at
+low and intermediate redshifts.",0601424v1
+2006-04-13,Unveiling Hidden Patterns in CMB Anisotropy Maps,"Bianchi VII_h models have been recently proposed to explain potential
+anomalies in the CMB anisotropy as observed by WMAP. We investigate the
+violation of statistical isotropy due to an embedded Bianchi VII_h templates in
+the CMB anisotropy maps to determine whether the existence of a hidden Bianchi
+template in the WMAP data is consistent with the previous null detection of the
+bipolar power spectrum in the WMAP first year maps. We argue that although
+correcting the WMAP maps for the Bianchi template may explain some features in
+the WMAP data it may cause other anomalies such as preferred directions leading
+to detectable levels of violation of statistical isotropy in the Bianchi
+corrected maps. We compute the bipolar power spectrum for the low density
+Bianchi VII_h models embedded in the background CMB anisotropy maps with the
+power spectrum that have been shown in recent literature to best fit the first
+year WMAP data. By examining statistical isotropy of these maps, we put a limit
+of {\sigma/H}_0 < 2.77E-10 (99% CL) on the shear parameter in Bianchi VII_h
+models.",0604279v2
+2006-07-20,Is there a chance that the anisotropies in the cosmic microwave background detected by COBE are an artefact of COBE's image reconstruction?,"The COBE time ordered data (TOD) was reanalysed for anisotropies in the
+cosmic microwave background with a novel technique that is much simpler and
+more robust than used in the official analysis of the COBE TOD. The technique
+extends the statistical concept of rejecting the null hypothesis to image
+reconstruction by asking if the TOD is consistent with no anisotropies outside
+the galactic band. If it is assumed that the instrumentation noise is ideal, as
+appears to be the case in the official analysis, the null hypothesis can be
+rejected to 28 sigma, a highly significant detection. However, the official
+analysis presents no information supporting the ideal noise assumption to the
+level required to reject the null hypothesis. The interaction of COBE's
+calibration error of roughly 3.0% with the brightest regions of the galactic
+band in combination with the reconstruction algorithm may have introduced
+artefacts roughly of the size and spectral signature of the 10ppm anisotropies
+reported by COBE. Data from follow up missions have similar problems with
+calibration errors that may have resulted in similar sky maps to COBE. It is
+pointed out that either a few hours of repetitive circular scans using the WMAP
+satellite or the single beam antenna of the soon-to-be-launched Planck
+satellite should provide definitive evidence as to the existence or non
+existence of the 10ppm anisotropies without the use of image reconstruction.",0607484v5
+2006-12-16,Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of cosmic gamma-ray background,"The origin of the cosmic gamma-ray background (CGB) is a longstanding mystery
+in high-energy astrophysics. Possible candidates include ordinary astrophysical
+objects such as unresolved blazars, as well as more exotic processes such as
+dark matter annihilation. While it would be difficult to distinguish them from
+the mean intensity data alone, one can use anisotropy data instead. We
+investigate the CGB anisotropy both from unresolved blazars and dark matter
+annihilation (including contributions from dark matter substructures), and find
+that the angular power spectra from these sources are very different. We then
+focus on detectability of dark matter annihilation signals using the anisotropy
+data, by treating the unresolved blazar component as a known background. We
+find that the dark matter signature should be detectable in the angular power
+spectrum of the CGB from two-year all-sky observations with the Gamma Ray Large
+Area Space Telescope (GLAST), as long as the dark matter annihilation
+contributes to a reasonable fraction, e.g., >~ 0.3, of the CGB at around 10
+GeV. We conclude that the anisotropy measurement of the CGB with GLAST should
+be a powerful tool for revealing the CGB origin, and potentially for the first
+detection of dark matter annihilation.",0612467v2
+2000-03-13,Bond and charge density waves in the isotropic interacting two-dimensional quarter-filled band and the insulating state proximate to organic superconductivity,"We report two surprising results regarding the nature of the spatial broken
+symmetries in the two-dimensional (2D), quarter-filled band with strong
+electron-electron interactions. First, in direct contradiction to the
+predictions of one-electron theory, we find a coexisting ``bond-order and
+charge density wave'' (BCDW) insulating ground state in the 2D rectangular
+lattice for all anisotropies, including the isotropic limit. Second, we find
+that the BCDW further coexists with a spin-density wave (SDW) in the range of
+large anisotropy. Further, in contrast to the interacting half-filled band, in
+the interacting quarter-filled band there are two transitions: first, a similar
+singlet-to-AFM/SDW transition for large anisotropy and second, an
+AFM/SDW-to-singlet transition at smaller anisotropy. We discuss how these
+theoretical results apply to the insulating states that are proximate to the
+superconducting states of 2:1 cationic charge-transfer solids (CTS).
+  An important consequence of this work is the suggestion that organic
+superconductivity is related to the proximate Coulomb-induced BCDW, with the
+SDW that coexists for large anisotropies being also a consequence of the BCDW,
+rather than the driver of superconductivity.",0003200v2
+2000-10-07,Enhanced Bound State Formation in Two Dimensions via Stripe-Like Hopping Anisotropies,"We have investigated two-electron bound state formation in a square
+two-dimensional t-J-U model with hopping anisotropies for zero electron
+density; these anisotropies are introduced to mimic the hopping energies
+similar to those expected in stripe-like arrangements of holes and spins found
+in various transition metal oxides. In this report we provide analytical
+solutions to this problem, and thus demonstrate that bound-state formation
+occurs at a critical exchange coupling, J_c, that decreases to zero in the
+limit of extreme hopping anisotropy t_y/t_x -> 0. This result should be
+contrasted with J_c/t = 2 for either a one-dimensional chain, or a
+two-dimensional plane with isotropic hopping. Most importantly, this behaviour
+is found to be qualitatively similar to that of two electrons on the two-leg
+ladder problem in the limit of t_interchain/t_intrachain -> 0. Using the latter
+result as guidance, we have evaluated the pair correlation function, thus
+determining that the bound state corresponds to one electron moving along one
+chain, with the second electron moving along the opposite chain, similar to two
+electrons confined to move along parallel, neighbouring, metallic stripes. We
+emphasize that the above results are not restricted to the zero density limit -
+we have completed an exact diagonalization study of two holes in a 12 X 2
+two-leg ladder described by the t-J model and have found that the
+above-mentioned lowering of the binding energy with hopping anisotropy persists
+near half filling.",0010116v1
+2003-07-05,Domain-wall profile in the presence of anisotropic exchange interactions: Effective on-site anisotropy,"Starting from a D-dimensional XXZ ferromagnetic Heisenberg model in an
+hypercubic lattice, it is demonstrated that the anisotropy in the exchange
+coupling constant leads to a D-dependent effective on-site anisotropy
+interaction often ignored for D>1. As a result the effective width of the wall
+depends on the dimensionality of the system. It is shown that the effective
+one-dimensional Hamiltonian is not the one-dimensional XXZ version as assumed
+in previous theoretical work. We derive a new expression for the wall profile
+that generalizes the standard Landau-Lifshitz form. Our results are found to be
+in very good agreement with earlier numerical work using the Monte Carlo
+method. Preceding theories concerning the domain wall contribution to
+magnetoresistance have considered the role of D only through the modification
+of the density of states in the electronic band structure. This Brief Report
+reveals that the wall profile itself contains an additional D dependence for
+the case of anisotropic exchange interactions.",0307120v2
+2005-05-12,"Perpendicular magnetization reversal, magnetic anisotropy, multi-step spin switching, and domain nucleation and expansion in Ga1-xMnxAs films","We present a comprehensive study of the reversal process of perpendicular
+magnetization in thin layers of the ferromagnetic semiconductor Ga1-xMnxAs. For
+this investigation we have purposely chosen Ga1-xMnxAs with a low Mn
+concentration (x ~ 0.02), since in such specimens contributions of cubic and
+uniaxial anisotropy parameters are comparable, allowing us to identify the role
+of both types of anisotropy in the magnetic reversal process. As a first step
+we have systematically mapped out the angular dependence of ferromagnetic
+resonance in thin Ga1-xMnxAs layers, which is a highly effective tool for
+obtaining the magnetic anisotropy parameters of the material. The process of
+perpendicular magnetization reversal was then studied by magneto-transport
+(i.e., Hall effect and planar Hall effect measurements). These measurements
+enable us to observe coherent spin rotation and non-coherent spin switching
+between the (100) and (010) planes. A model is proposed to explain the observed
+multi-step spin switching. The agreement of the model with experiment indicates
+that it can be reliably used for determining magnetic anisotropy parameters
+from magneto-transport data. An interesting characteristic of perpendicular
+magnetization reversal in Ga1-xMnxAs with low x is the appearance of a double
+hysteresis loops in the magnetization data. This double-loop behavior can be
+understood by generalizing the proposed model to include the processes of
+domain nucleation and expansion.",0505322v1
+2005-12-12,Angular Dependence of Exchange Anisotropy on Cooling Field in FM/Fluoride Thin Films,"Exchange anisotropy in ferromagnet/antiferromagnet (FM/AF) films is usually
+introduced along the cooling field or FM magnetization direction. Here we
+investigate the dependence of the exchange anisotropy, loop bifurcation, and
+reversal mechanism on the cooling field direction using vector magnetometry.
+Three types of samples (FM=Fe, Ni /AF = FeF2, MnF2) have been studied where the
+AF layer is epitaxial (110), twinned (110), and polycrystalline. With an
+epitaxial AF which has one spin axis, the cooling field orients the exchange
+field along the spin axis. Applying the cooling field perpendicular to the spin
+axis results in bifurcated loops, whose shape evolves with the cooling field
+geometry and strength. With a twinned AF where there are two orthogonal spin
+axes, the exchange field direction is along the bisector of the spin axes that
+encompass the cooling field. With a polycrystalline AF, the exchange field
+direction is the same as the cooling field. Transverse hysteresis loops show
+that when the exchange field has a component perpendicular to the applied
+field, the magnetization reversal occurs by rotation in the direction of the
+perpendicular component. Our results demonstrate that in fluoride films, the
+exchange field is established primarily by the AF anisotropy direction, and
+only to a lesser extent the cooling field or the magnetization direction. The
+bifurcated loops are due to a distribution of AF anisotropies and large AF
+domain sizes. Furthermore, the magnetization reversal process is extremely
+sensitive to the exchange field direction.",0512257v1
+2006-06-28,The random-anisotropy model in the strong-anisotropy limit,"We investigate the nature of the critical behaviour of the random-anisotropy
+Heisenberg model (RAM), which describes a magnetic system with random uniaxial
+single-site anisotropy, such as some amorphous alloys of rare earths and
+transition metals. In particular, we consider the strong-anisotropy limit
+(SRAM), in which the Hamiltonian can be rewritten as the one of an Ising
+spin-glass model with correlated bond disorder: H = - J \sum_{< xy >} j_{xy}
+\sigma_x \sigma_y, where j_{xy} = \vec{u}_x \cdot \vec{u}_y and \vec{u}_x is a
+random three-component unit vector. We performed Monte Carlo simulations of the
+SRAM on simple cubic L^3 lattices, up to L=30, measuring correlation functions
+of the replica-replica overlap, which is the order parameter at a glass
+transition. The corresponding results show critical behaviour and finite-size
+scaling. They provide evidence of a finite-temperature continuous transition
+with critical exponents \eta_o=-0.24(4) and \nu_o=2.4(6). These results are
+close to the corresponding estimates that have been obtained in the usual Ising
+spin-glass model with uncorrelated bond disorder, suggesting that the two
+models belong to the same universality class. This is consistent with arguments
+that suggest that the disorder correlations present in the SRAM are irrelevant.",0606728v1
+2004-11-03,Probing anisotropies of gravitational-wave backgrounds with a space-based interferometer: geometric properties of antenna patterns and their angular power,"We discuss the sensitivity to anisotropies of stochastic gravitational-wave
+backgrounds (GWBs) observed via space-based interferometer. In addition to the
+unresolved galactic binaries as the most promising GWB source of the planned
+Laser Interferometer Space Antenna (LISA), the extragalactic sources for GWBs
+might be detected in the future space missions. The anisotropies of the GWBs
+thus play a crucial role to discriminate various components of the GWBs. We
+study general features of antenna pattern sensitivity to the anisotropies of
+GWBs beyond the low-frequency approximation. We show that the sensitivity of
+space-based interferometer to GWBs is severely restricted by the data
+combinations and the symmetries of the detector configuration. The spherical
+harmonic analysis of the antenna pattern functions reveals that the angular
+power of the detector response increases with frequency and the detectable
+multipole moments with effective sensitivity h_{eff} \sim 10^{-20} Hz^{-1/2}
+may reach $\ell \sim$ 8-10 at $f \sim f_*=10$ mHz in the case of the single
+LISA detector. However, the cross correlation of optimal interferometric
+variables is blind to the monopole (\ell=0) intensity anisotropy, and also to
+the dipole (\ell=1) in some case, irrespective of the frequency band. Besides,
+all the self-correlated signals are shown to be blind to the odd multipole
+moments (\ell=odd), independently of the frequency band.",0411017v2
+2007-01-27,Thermodynamics of Ideal Boson and Fermion Gases in the Static Taub Universe,"Some thermodynamic quantities of nonrelativistic ideal boson and fermion
+gases in the static Taub universe are derived to first order in a small
+anisotropy parameter d which measuring the deformation from the spherical
+Einstein universe. They are used to investigate the problem of how the
+curvature anisotropy affects the thermodynamic behaviors of an ideal gas. It is
+found that, when the universe is in the oblate configuration (i.e., d > 0), the
+effect of curvature anisotropy is to increase the number of the fraction in the
+Bose-Einstein condensation and to decrease the fermion distribution function at
+low temperature. When the universe is in the prolate configuration (i.e., d <
+0), the effects of curvature anisotropy on the thermodynamic quantities is
+contrary to that in the oblate configuration. The density matrix of a two
+particle system is evaluated and it is used to define the ""statistical
+interparticle potential"" as an attempt to give a ""statistical interpretation""
+about the found thermodynamic behaviors. It is found that when the universe is
+in the oblate (prolate) configuration the curvature anisotropy will enhance
+(reduce) both the ""statistic attraction"" among the bosons and ""statistical
+repulsion"" among the fermions. It is expected that such a behavior will also be
+shown in the relativistic system.",0701147v1
+2000-10-16,Anomalous scaling in two models of the passive scalar advection: Effects of anisotropy and compressibility,"The problem of the effects of compressibility and large-scale anisotropy on
+anomalous scaling behavior is considered for two models describing passive
+advection of scalar density and tracer fields. The advecting velocity field is
+Gaussian, $\delta$-correlated in time, and scales with a positive exponent
+$\epsilon$. Explicit inertial-range expressions for the scalar correlation
+functions are obtained; they are represented by superpositions of power laws
+with nonuniversal amplitudes and universal (dependent only on $\epsilon$ and
+$\alpha$, the compressibility parameter) anomalous exponents. The complete set
+of anomalous exponents for the pair correlation functions is found
+nonperturbatively, in any space dimension d, using the zero-mode technique. For
+higher-order correlation functions, the anomalous exponents are calculated to
+$O(\epsilon^{2})$ using the renormalization group. Like in the incompressible
+case, the exponents exhibit a hierarchy related to the degree of anisotropy:
+the leading contributions to the even correlation functions are given by the
+exponents from the isotropic shell, in agreement with the idea of restored
+small-scale isotropy. As the degree of compressibility increases, the
+corrections become closer to the leading terms. The small-scale anisotropy
+reveals itself in the odd ratios of correlation functions: the skewness factor
+is slowly decreasing going down to small scales for the incompressible case,
+but becomes increasing if $\alpha$ is large enough. The higher odd
+dimensionless ratios (hyperskewness etc.) increase, thus signalling the
+persistent small-scale anisotropy; this effect becomes more pronounced for
+larger values of $\alpha$.",0010029v1
+2002-08-02,Field-dependent surface impedance tensor in amorphous wires with two types of magnetic anisotropy: helical and circumferential,"This paper concerns the theoretical and experimental investigation of the
+magneto-impedance (MI) effect in amorphous wires in terms of the surface
+impedance tensor. Physical concepts of MI and problems of significant practical
+importance are discussed using the results obtained. The theoretical analysis
+is based on employing the asymptotic-series expansion method of solving the
+Maxwell equations for a ferromagnetic wire with an ac permeability tensor of a
+general form associated with magnetisation rotation. The magnetic
+structure-dependent impedance tensor is calculated for any frequency and
+external magnetic field, and is not restricted to the case when only strong
+skin-effect is present. This approach allows us to develop a rigorous
+quantitative analysis of MI characteristics in wires, depending on the type of
+magnetic anisotropy, the magnitude of dc bias current, and an excitation
+method. The theoretical model has been tested by comparing the obtained results
+with experiment. For the sake of an adequate comparison, the full impedance
+tensor is measured in CoFeSiB and CoSiB amorphous wires having a
+circumferential and helical anisotropy, respectively, by determining the S21
+parameter. In cases, when the rotational dynamics is responsible for the
+impedance behaviour, there is a reasonable agreement between the experimental
+and theoretical results. Such effects as the ac biased asymmetrical MI in wires
+with a circumferential anisotropy, the transformation in MI behaviour caused by
+a dc current (from that having a symmetric hysteresis to an asymmetric
+anhysteretic one) in wires with a helical anisotropy are discussed.",0208012v1
+2006-10-11,A New Light-Speed Anisotropy Experiment: Absolute Motion and Gravitational Waves Detected,"Data from a new experiment measuring the anisotropy of the one-way speed of
+EM waves in a coaxial cable, gives the speed of light as 300,000+/-400+/-20km/s
+in a measured direction RA=5.5+/-2hrs, Dec=70+/-10deg S, is shown to be in
+excellent agreement with the results from seven previous anisotropy
+experiments, particularly those of Miller (1925/26), and even those of
+Michelson and Morley (1887). The Miller gas-mode interferometer results, and
+those from the RF coaxial cable experiments of Torr and Kolen (1983), De Witte
+(1991) and the new experiment all reveal the presence of gravitational waves,
+as indicated by the last +/- variations above, but of a kind different from
+those supposedly predicted by General Relativity. The understanding of the
+operation of the Michelson interferometer in gas-mode was only achieved in 2002
+and involved a calibration for the interferometer that necessarily involved
+Special Relativity effects and the refractive index of the gas in the light
+paths. The results demonstrate the reality of the Fitzgerald-Lorentz
+contraction as an observer independent relativistic effect. A common
+misunderstanding is that the anisotropy of the speed of light is necessarily in
+conflict with Special Relativity and Lorentz symmetry - this is explained. All
+eight experiments and theory show that we have both anisotropy of the speed of
+light and relativistic effects, and that a dynamical 3-space exists - that
+absolute motion through that space has been repeatedly observed since 1887.
+These developments completely change fundamental physics and our understanding
+of reality.",0610076v1
+1997-03-19,Quantum Noise and Polarization Fluctuations in Vertical Cavity Surface Emitting Lasers,"We investigate the polarization fluctuations caused by quantum noise in
+quantum well vertical cavity surface emitting lasers (VCSELs). Langevin
+equations are derived on the basis of a generalized rate equation model in
+which the influence of competing gain-loss and frequency anisotropies is
+included. This reveals how the anisotropies and the quantum well confinement
+effects shape the correlations and the magnitude of fluctuations in ellipticity
+and in polarization direction. According to our results all parameters used in
+the rate equations may be obtained experimentally from precise time resolved
+measurements of the intensity and polarization fluctuations in the emitted
+laser light. To clarify the effects of anisotropies and of quantum well
+confinement on the laser process in VCSELs we therefore propose time resolved
+measurements of the polarization fluctuations in the laser light. In
+particular, such measurements allow to distinguish the effects of frequency
+anisotropy and of gain-loss anisotropy and would provide data on the spin
+relaxation rate in the quantum well structure during cw operation as well as
+representing a new way of experimentally determinig the linewidth enhancement
+factor alpha.",9703034v1
+2007-04-09,Excitation Spectrum Gap and Spin-Wave Stiffness of XXZ Heisenberg Chains: Global Renormalization-Group Calculation,"The anisotropic XXZ spin-1/2 Heisenberg chain is studied using
+renormalization-group theory. The specific heats and nearest-neighbor spin-spin
+correlations are calculated thoughout the entire temperature and anisotropy
+ranges in both ferromagnetic and antiferromagnetic regions, obtaining a global
+description and quantitative results. We obtain, for all anisotropies, the
+antiferromagnetic spin-liquid spin-wave velocity and the Isinglike
+ferromagnetic excitation spectrum gap, exhibiting the spin-wave to spinon
+crossover. A number of characteristics of purely quantum nature are found: The
+in-plane interaction s_i^x s_j^x + s_i^y s_j^y induces an antiferromagnetic
+correlation in the out-of-plane s_i^z component, at higher temperatures in the
+antiferromagnetic XXZ chain, dominantly at low temperatures in the
+ferromagnetic XXZ chain, and, in-between, at all temperatures in the XY chain.
+We find that the converse effect also occurs in the antiferromagnetic XXZ
+chain: an antiferromagnetic s_i^z s_j^z interaction induces a correlation in
+the s_i^xy component. As another purely quantum effect, (i) in the
+antiferromagnet, the value of the specific heat peak is insensitive to
+anisotropy and the temperature of the specific heat peak decreases from the
+isotropic (Heisenberg) with introduction of either type (Ising or XY)
+anisotropy; (ii) in complete contrast, in the ferromagnet, the value and
+temperature of the specific heat peak increase with either type of anisotropy.",0704.1064v2
+2007-06-18,Some physical displays of the space anisotropy relevant to the feasibility of its being detected at a laboratory,"The impact of local space anisotropy on the transverse Doppler effect is
+examined. Two types of laboratory experiments aimed at seeking and measuring
+the local space anisotropy are proposed. In terms of the conventional special
+relativity theory, which treats 3D space to be locally isotropic, the
+experiments are of the type of ``null-experiments''. In the first-type
+experiments, a feasible Doppler shift of frequency is measured by the
+M\""ossbauer effect, with the M\""ossbauer source and absorber being located at
+two identical and diametrically opposed distances from the center of a rapidly
+rotating rotor, while the $\gamma$-quanta are recorded by two stationary and
+oppositely positioned proportional counters. Either of the counters records
+only those $\gamma$-quanta that passed through the absorber at the moment of
+the passage of the latter near a counter. The second-type experiments are made
+using the latest radio physics techniques for generating monochromatic
+oscillations and for recording weak signals. The effect expected due to space
+anisotropy consists in frequency modulation of the harmonic oscillations coming
+to a receiver that rotates at a constant velocity around the monochromatic wave
+emitter. In this case the modulation depth proves to be proportional to the
+space anisotropy magnitude.",0706.2621v1
+2008-04-08,Piezo-control of magnetic anisotropy in GaMnAs: Reversible manipulation of magnetization orientation and irreversible magnetization switching,"We have investigated the magnetic properties of a piezoelectric
+actuator/ferromagnetic semiconductor hybrid structure. Using a GaMnAs epilayer
+as the ferromagnetic semiconductor and applying the piezo-stress along its
+[110] direction, we quantify the magnetic anisotropy as a function of the
+voltage V_p applied to the piezoelectric actuator using anisotropic
+magnetoresistance techniques. We find that the easy axis of the strain-induced
+uniaxial magnetic anisotropy contribution can be inverted from the [110] to the
+[1-10] direction via the application of appropriate voltages V_p. At T=5K the
+magnetoelastic term is a minor contribution to the magnetic anisotropy.
+Nevertheless, we show that the switching fields of rho(H) loops are shifted as
+a function of V_p at this temperature. At 50K - where the magnetoelastic term
+dominates the magnetic anisotropy - we are able to tune the magnetization
+orientation by about 70 degree solely by means of the electrical voltage V_p
+applied. Furthermore, we derive the magnetostrictive constant lambda_111 as a
+function of temperature and find values consistent with earlier results. We
+argue that the piezo-voltage control of magnetization orientation is directly
+transferable to other ferromagnetic/piezoelectric hybrid structures, paving the
+way to innovative multifunctional device concepts. As an example, we
+demonstrate piezo-voltage induced irreversible magnetization switching at
+T=40K, which constitutes the basic principle of a nonvolatile memory element.",0804.1336v1
+2009-01-28,A Measurement of Arcminute Anisotropy in the Cosmic Microwave Background with the Sunyaev-Zel'dovich Array,"We present 30 GHz measurements of the angular power spectrum of the cosmic
+microwave background (CMB) obtained with the Sunyaev-Zel'dovich Array. The
+measurements are sensitive to arcminute angular scales, where secondary
+anisotropy from the Sunyaev-Zel'dovich effect (SZE) is expected to dominate.
+For a broad bin centered at multipole 4066 we find 67+77-50 uK^2, of which
+26+/-5 uK^2 is the expected contribution from primary CMB anisotropy and
+80+/-54 uK^2 is the expected contribution from undetected radio sources. These
+results imply an upper limit of 155 uK^2 (95% CL) on the secondary contribution
+to the anisotropy in our maps. This level of SZE anisotropy power is consistent
+with expectations based on recent determinations of the normalization of the
+matter power spectrum, i.e., sigma_8~0.8.",0901.4342v2
+2009-05-18,Structure of energy level degeneracy of a single-spin model from a view point of symmetry of the spin anisotropy and its nontrivial spin($S$)-dependence on the higher order anisotropy,"We study structure of the gapless points (diabolical points) at zero magnetic
+field ($H_z=0$) of single-spin models with spin anisotropies. Nontrivial
+appearance of diabolical points at finite transverse field $H_x$ has been
+studied from the view point of interference of the Berry phase, and related
+phenomena have been experimentally found in the single molecular magnet Fe$_8$.
+We study effects of the orthorhombic single-ion anisotropy $E(S_+^2+S_-^2)$ and
+find a symmetry associated with the degeneracy, which provides a clear picture
+of the global structure of energy level diagram including the excited states.
+Moreover, we study effects of the higher order anisotropy $C(S_+^4+S_-^4)$, and
+find that, in contrast to the semiclassical limit $(S\to\infty)$, location of a
+pair annihilation of the diabolical point does not coincides with a point at
+which a pair of diabolical points appears in nonzero $H_y$ space(bifurcation
+points). Distance between the annihilation and bifurcation points vanishes when
+$S\to\infty$, which restores the semiclassical result. We obtain a complete
+structure of the diabolical points in the $(C,H_x)$ plane.",0905.2780v2
+2009-09-18,Detecting Gamma-Ray Anisotropies from Decaying Dark Matter: Prospects for Fermi LAT,"Decaying dark matter particles could be indirectly detected as an excess over
+a simple power law in the energy spectrum of the diffuse extragalactic
+gamma-ray background. Furthermore, since the Earth is not located at the center
+of the Galactic dark matter halo, the exotic contribution from dark matter
+decay to the diffuse gamma-ray flux is expected to be anisotropic, offering a
+complementary method for the indirect search for decaying dark matter
+particles. In this paper we discuss in detail the expected dipole-like
+anisotropies in the dark matter signal, taking also into account the radiation
+from inverse Compton scattering of electrons and positrons from dark matter
+decay. A different source for anisotropies in the gamma-ray flux are the dark
+matter density fluctuations on cosmic scales. We calculate the corresponding
+angular power spectrum of the gamma-ray flux and comment on observational
+prospects. Finally, we calculate the expected anisotropies for the decaying
+dark matter scenarios that can reproduce the electron/positron excesses
+reported by PAMELA and the Fermi LAT, and we estimate the prospects for
+detecting the predicted gamma-ray anisotropy in the near future.",0909.3514v2
+2009-11-18,Anisotropic nonlinear elasticity in a spherical bead pack: influence of the fabric anisotropy,"Stress-strain measurements and ultrasound propagation experiments in glass
+bead packs have been simultaneously conducted to characterize the
+stress-induced anisotropy under uniaxial loading. These measurements, realized
+respectively with finite and incremental deformations of the granular assembly,
+are analyzed within the framework of the effective medium theory based on the
+Hertz-Mindlin contact theory. Our work shows that both compressional and shear
+wave velocities and consequently the incremental elastic moduli agree fairly
+well with the effective medium model by Johnson et al. [J. Appl. Mech. 65, 380
+(1998)], but the anisotropic stress ratio resulting from finite deformation
+does not at all. As indicated by numerical simulations, the discrepancy may
+arise from the fact that the model doesn't properly allow the grains to relax
+from the affine motion approximation. Here we find that the interaction nature
+at the grain contact could also play a crucial role for the relevant prediction
+by the model; indeed, such discrepancy can be significantly reduced if the
+frictional resistance between grains is removed. Another main experimental
+finding is the influence of the inherent anisotropy of granular packs, realized
+by different protocols of the sample preparation. Our results reveal that
+compressional waves are more sensitive to the stress-induced anisotropy,
+whereas the shear waves are more sensitive to the fabric anisotropy, not being
+accounted in analytical effective medium models.",0911.3542v1
+2010-05-05,Anisotropies in the Diffuse Gamma-Ray Background from Dark Matter with Fermi LAT: a closer look,"We perform a detailed study of the sensitivity to the anisotropies related to
+Dark Matter (DM) annihilation in the Isotropic Gamma-Ray Background (IGRB) as
+measured by the Fermi Large Area Telescope (Fermi-LAT). For the first time, we
+take into account the effects of the Galactic foregrounds and use a realistic
+representation of the Fermi-LAT. We consider DM anisotropies of extra-galactic
+origin and of Galactic origin (which can be generated through annihilation in
+the Milky Way sub-structures) as opposed to a background of anisotropies
+generated by sources of astrophysical origin, blazars for example. We find that
+with statistics from 5 years of observation Fermi is sensitive to a DM
+contribution at the level of the thermal-relic cross section depending on the
+DM mass and annihilation mode. The anisotropy method for DM searches has a
+sensitivity comparable to the usual methods based only on the energy spectrum
+and thus constitutes an independent and complementary piece of information in
+the DM puzzle. (abridged)",1005.0843v2
+2010-07-28,Cosmological density perturbations from conformal scalar field: infrared properties and statistical anisotropy,"We consider a scenario in which primordial scalar perturbations are generated
+when complex conformal scalar field rolls down its negative quartic potential.
+Initially, these are the perturbations of the phase of this field; they are
+converted into the adiabatic perturbations at a later stage. A potentially
+dangerous feature of this scenario is the existence of perturbations in the
+radial field direction, which have red power spectrum. We show, however, that
+to the linear order in the small parameter - the quartic self-coupling - the
+infrared effects are completely harmless, as they can be absorbed into field
+redefinition. We then evaluate the statistical anisotropy inherent in the model
+due to the existence of the long-ranged radial perturbations. To the linear
+order in the quartic self-coupling the statistical anisotropy is free of the
+infrared effects. The latter show up at the quadratic order in the
+self-coupling and result in the mild (logarithmic) enhancement of the
+corresponding contribution to the statistical anisotropy. The resulting
+statistical anisotropy is a combination of a larger term which, however, decays
+as momentum increases, and a smaller term which is independent of momentum.",1007.4949v2
+2010-09-03,Local Anisotropy of Fluids using Minkowski Tensors,"Statistics of the free volume available to individual particles have
+previously been studied for simple and complex fluids, granular matter,
+amorphous solids, and structural glasses. Minkowski tensors provide a set of
+shape measures that are based on strong mathematical theorems and easily
+computed for polygonal and polyhedral bodies such as free volume cells (Voronoi
+cells). They characterize the local structure beyond the two-point correlation
+function and are suitable to define indices $0\leq \beta_\nu^{a,b}\leq 1$ of
+local anisotropy. Here, we analyze the statistics of Minkowski tensors for
+configurations of simple liquid models, including the ideal gas (Poisson point
+process), the hard disks and hard spheres ensemble, and the Lennard-Jones
+fluid. We show that Minkowski tensors provide a robust characterization of
+local anisotropy, which ranges from $\beta_\nu^{a,b}\approx 0.3$ for vapor
+phases to $\beta_\nu^{a,b}\to 1$ for ordered solids. We find that for fluids,
+local anisotropy decreases monotonously with increasing free volume and
+randomness of particle positions. Furthermore, the local anisotropy indices
+$\beta_\nu^{a,b}$ are sensitive to structural transitions in these simple
+fluids, as has been previously shown in granular systems for the transition
+from loose to jammed bead packs.",1009.0601v2
+2010-11-11,Competition between supersolid phases and magnetisation plateaux in the frustrated easy-axis antiferromagnet on a triangular lattice,"The majority of magnetic materials possess some degree of magnetic
+anisotropy, either at the level of a single ion, or in the exchange
+interactions between different magnetic ions. Where these exchange interactions
+are also frustrated, the competition between them and anisotropy can stabilize
+a wide variety of new phases in applied magnetic field. Motivated by the
+hexagonal delafossite 2H-AgNiO 2, we study the Heisenberg antiferromagnet on a
+layered triangular lattice with competing first- and second-neighbour
+interactions and single-ion easy-axis anisotropy. Using a combination of
+classical Monte Carlo simulation, mean-field analysis, and Landau theory, we
+establish the magnetic phase diagram of this model as a function of temperature
+and magnetic field for a fixed ratio of exchange interactions, but with values
+of easy-axis anisotropy D extending from the Heisenberg (D =0) to the Ising
+(D=&#8734) limits. We uncover a rich variety of different magnetic phases.
+These include several phases which are magnetic supersolids (in the sense of
+Matsuda and Tstuneto or Liu and Fisher), one of which may already have been
+observed in AgNiO 2. We explore how this particular supersolid arises through
+the closing of a gap in the spin-wave spectrum, and how it competes with rival
+collinear phases as the easy-axis anisotropy is increased. The finite
+temperature properties of this phase are found to be different from those of
+any previously studied magnetic supersolid.",1011.2698v2
+2011-03-22,Dipolar Interactions between Iron-Oxide Nanoparticles in Frozen Ferrofluids and Ferronematics,"We present a detailed study of the magnetic behavior of iron-oxide
+(gamma-Fe2O3 and Fe3O4) nanoparticles constituents of ferrofluids (FF's) with
+average particle sizes <d> = 2.5 and 10 nm. The particles were dispersed in the
+frozen liquid carrier (pure FF) and in a frozen lyotropic liquid crystalline
+matrix in the nematic phase or ferronematic (FN) (ferrolyomesophase). Both FF
+and FN phases displayed superparamagnetic (SPM) behaviour at room temperature,
+with blocking temperatures T_B ~ 10 and 100 K for <d> = 2.5 and 10 nm,
+respectively. Dynamic ac susceptibility measurements showed a thermally
+activated N\'eel-Brown dependence of the blocking temperature with applied
+frequency. Our results show that dipolar interactions are small, but
+non-negligible, as compared to the single-particle energy barriers from
+magnetic anisotropy. From the fit of ac susceptibility we calculated the
+effective magnetic anisotropy constant K_{eff} for 2.5 nm maghemite particles.
+Although interparticle interactions present in highly diluted samples do not
+appreciably modify the dynamic magnetic behavior of isolated particles, the
+calculated magnetic anisotropy were abut one order of magnitude larger that the
+bulk materials, suggesting the existence of large surface anisotropy. Using the
+thermally activated model to fit the dynamic data yielded effective energy
+barriers Ea = 3.5x10^{-21} J. From these data, we obtained K_{eff} = 422 kJ/m^3
+for the single-particle effective magnetic anisotropy.",1103.4403v1
+2011-03-23,"On the origin of non-monotonic doping dependence of the in-plane resistivity anisotropy in Ba(Fe$_{1-x}T_x$)$_2$As$_2$, $T$ = Co, Ni and Cu","The in-plane resistivity anisotropy has been measured for detwinned single
+crystals of Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$ and Ba(Fe$_{1-x}$Cu$_x$)$_2$As$_2$.
+The data reveal a non-monotonic doping dependence, similar to previous
+observations for Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. Magnetotransport measurements
+of the parent compound reveal a non-linear Hall coefficient and a strong linear
+term in the transverse magnetoresistance. Both effects are rapidly suppressed
+with chemical substitution over a similar compositional range as the onset of
+the large in-plane resistivity anisotropy. It is suggested that the relatively
+small in-plane anisotropy of the parent compound in the spin density wave state
+is due to the presence of an isotropic, high mobility pocket of reconstructed
+Fermi surface. Progressive suppression of the contribution to the conductivity
+arising from this isotropic pocket with chemical substitution eventually
+reveals the underlying in-plane anisotropy associated with the remaining FS
+pockets.",1103.4535v2
+2011-03-31,Phase diagram for the $ν=0$ quantum Hall state in monolayer graphene,"The $\nu=0$ quantum Hall state in a defect-free graphene sample is studied
+within the framework of quantum Hall ferromagnetism. We perform a systematic
+analysis of the pseudospin anisotropies, which arise from the valley and
+sublattice asymmetric short-range electron-electron (e-e) and electron-phonon
+(e-ph) interactions. The phase diagram, obtained in the presence of generic
+pseudospin anisotropy and the Zeeman effect, consists of four phases
+characterized by the following orders: spin-polarized ferromagnetic, canted
+antiferromagnetic, charge density wave, and Kekul\'{e} distortion. We take into
+account the Landau level mixing effects and show that they result in the key
+renormalizations of parameters. First, the absolute values of the anisotropy
+energies become greatly enhanced and can significantly exceed the Zeeman
+energy. Second, the signs of the anisotropy energies due to e-e interactions
+can change upon renormalization. A crucial consequence of the latter is that
+the short-range e-e interactions alone could favor any state on the phase
+diagram, depending on the details of interactions at the lattice scale. On the
+other hand, the leading e-ph interactions always favor the Kekul\'{e}
+distortion order. The possibility of inducing phase transitions by tilting the
+magnetic field is discussed.",1103.6285v2
+2011-08-02,Velocity Anisotropy as a Diagnostic of the Magnetization of the Interstellar Medium and Molecular clouds,"We use a set of magnetohydrodynamics (MHD) simulations of fully-developed
+(driven) turbulence to study the anisotropy in the velocity field that is
+induced by the presence of the magnetic field. In our models we study
+turbulence characterized by sonic Mach numbers M_s from 0.7 to 7.5, and Alfven
+Mach numbers M_A from 0.4 to 7.7. These are used to produce synthetic
+observations (centroid maps) that are analyzed. To study the effect of large
+scale density fluctuations and of white noise we have modified the density
+fields and obtained new centroid maps, which are analyzed. We show that
+restricting the range of scales at which the anisotropy is measured makes the
+method robust against such fluctuations. We show that the anisotropy in the
+structure function of the maps reveals the direction of the magnetic field for
+M_A \lesssim 1.5, regardless of the sonic Mach number. We found that the degree
+of anisotropy can be used to determine the degree of magnetization (i.e. M_A)
+for M_A \lesssim 1.5. To do this, one needs an additional measure of the sonic
+Mach number and an estimate of the LOS magnetic field, both feasible by other
+techniques, offering a new opportunity to study the magnetization state of the
+interstellar medium.",1108.0693v1
+2011-09-19,Anisotropic spin-fluctuations in SmCoPO revealed by 31^P NMR measurement,"31^P NMR spectral features in polycrystalline SmCoPO reveal an axially
+symmetric local magnetic field. At low temperature, the anisotropy of the
+internal magnetic field increases rapidly, with K_ab increasing faster than
+that of K_c. The dominant contribution to this anisotropy arises from Sm-4f
+electron contribution over that of Co-3d. The intrinsic width 2*(Beta) deviates
+from linearity with respect to bulk susceptibility below 170 K due to the
+enhancement of (1/T_2)dynamic, which along with the continuous increase of
+anisotropy in the internal magnetic field is responsible for the wipe out
+effect of the NMR signal, well above T_C. 1/T_1 shows large anisotropy
+confirming a significant contribution of Sm-4f electron spin fluctuations to
+1/T_1, arising from indirect RKKY type exchange interaction indicating a
+non-negligible hybridization between Sm-4f orbitals and the conduction band,
+over the itinerant character of the Co-3d spins. This anisotropy in originates
+from the orientation dependence of chi""(q,omega). The 3d-spin fluctuations in
+the ab plane is 2D FM in nature, while along the c-axis, a signature of a weak
+2D AFM spin fluctuations superimposed on weak FM spin-fluctuations even in a
+field of 7 T and far above T_N is observed. The enhancement of this AFM
+fluctuations of the Co-3d spins along c-axis, at further low temperature is
+responsible to drive the system to an AFM ordered state.",1109.3955v3
+2011-10-28,Large peculiar motion of the solar system from the dipole anisotropy in sky brightness due to distant radio sources,"According to the cosmological principle, the Universe should appear
+isotropic, without any preferred directions, to an observer whom we may
+consider to be fixed in the co-moving co-ordinate system of the expanding
+Universe. Such an observer is stationary with respect to the average
+distribution of the matter in the Universe and the sky brightness at any
+frequency should appear uniform in all directions to such an observer. However
+a peculiar motion of such an observer, due to a combined effect of Doppler
+boosting and aberration, will introduce a dipole anisotropy in the observed sky
+brightness; in reverse an observed dipole anisotropy in the sky brightness
+could be used to infer the peculiar velocity of the observer with respect to
+the average Universe. We determine the peculiar velocity of the solar system
+relative to the frame of distant radio sources, by studying the anisotropy in
+the sky brightness from discrete radio sources, i.e., an integrated emission
+from discrete sources per unit solid angle. Our results give a direction of the
+velocity vector in agreement with the Cosmic Microwave Background Radiation
+(CMBR) value, but the magnitude ($\sim 1600\pm 400$ km/s) is $\sim 4$ times the
+CMBR value ($369\pm 1$ km/s) at a statistically significant ($\sim 3\sigma$)
+level. A genuine difference between the two dipoles would imply anisotropic
+Universe, with the anisotropy changing with the epoch. This would violate the
+cosmological principle where the isotropy of the Universe is assumed for all
+epochs, and on which the whole modern cosmology is based upon.",1110.6260v1
+2012-02-24,Band mass anisotropy and the intrinsic metric of fractional quantum Hall systems,"It was recently pointed out that topological liquid phases arising in the
+fractional quantum Hall effect (FQHE) are not required to be rotationally
+invariant, as most variational wavefunctions proposed to date have been.
+Instead, they possess a geometric degree of freedom corresponding to a shear
+deformation that acts like an intrinsic metric. We apply this idea to a system
+with an anisotropic band mass, as is intrinsically the case in many-valley
+semiconductors such as AlAs and Si, or in isotropic systems like GaAs in the
+presence of a tilted magnetic field, which breaks the rotational invariance. We
+perform exact diagonalization calculations with periodic boundary conditions
+(torus geometry) for various filling fractions in the lowest, first and second
+Landau levels. In the lowest Landau level, we demonstrate that FQHE states
+generally survive the breakdown of rotational invariance by moderate values of
+the band mass anisotropy. At 1/3 filling, we generate a variational family of
+Laughlin wavefunctions parametrized by the metric degree of freedom. We show
+that the intrinsic metric of the Laughlin state adjusts as the band mass
+anisotropy or the dielectric tensor are varied, while the phase remains robust.
+In the n=1 Landau level, mass anisotropy drives transitions between
+incompressible liquids and compressible states with charge density wave
+ordering. In n>=2 Landau levels, mass anisotropy selects and enhances stripe
+ordering with compatible wave vectors at partial 1/3 and 1/2 fillings.",1202.5586v1
+2012-06-05,"Underscreened Kondo effect in S=1 magnetic quantum dots: Exchange, anisotropy and temperature effects","We present a theoretical analysis of the effects of uniaxial magnetic
+anisotropy and contact-induced exchange field on the underscreened Kondo effect
+in S=1 magnetic quantum dots coupled to ferromagnetic leads. First, by using
+the second-order perturbation theory we show that the coupling to
+spin-polarized electrode results in an effective exchange field $B_{\rm eff}$
+and an effective magnetic anisotropy $D_{\rm eff}$. Second, we confirm these
+findings by using the numerical renormalization group method, which is employed
+to study the dependence of the quantum dot spectral functions, as well as
+quantum dot spin, on various parameters of the system. We show that the
+underscreened Kondo effect is generally suppressed due to the presence of
+effective exchange field and can be restored by tuning the anisotropy constant,
+when $|D_{\rm eff}| = |B_{\rm eff}|$. The Kondo effect can also be restored by
+sweeping an external magnetic field, and the restoration occurs twice in a
+single sweep. From the distance between the restored Kondo resonances one can
+extract the information about both the exchange field and the effective
+anisotropy. Finally, we calculate the temperature dependence of linear
+conductance for the parameters where the Kondo effect is restored and show that
+the restored Kondo resonances display a universal scaling of $S=1/2$ Kondo
+effect.",1206.1034v2
+2012-06-21,A Novel Approach to Constrain the Escape Fraction and Dust Content at High Redshift Using the Cosmic Infrared Background Fractional Anisotropy,"The Cosmic Infrared Background (CIB) provides an opportunity to constrain
+many properties of the high redshift (z>6) stellar population as a whole. This
+background, specifically, from 1 to 200 microns, will contain any information
+about the era of reionization and the stars responsible for producing these
+ionizing photons. In this paper, we look at the fractional anisotropy delta I/I
+of this high redshift population, which is the ratio of the magnitude of the
+fluctuations (delta I) and the mean intensity (I). We show that this can be
+used to constrain the escape fraction of the population as a whole. The
+magnitude of the fluctuations of the CIB depend on the escape fraction, while
+the mean intensity does not. This results in lower values of the escape
+fraction producing higher values of the fractional anisotropy. This difference
+is predicted to be larger at the longer wavelengths bands (above 10 microns),
+albeit it is also much harder to observe in that range. We show that the
+fractional anisotropy can also be used to separate a dusty from a dust-free
+population. Finally, we discuss the constraints provided by current
+observations on the CIB fractional anisotropy.",1206.4934v2
+2012-07-23,Vlasov simulations of multi-ion plasma turbulence in the solar wind,"Hybrid Vlasov-Maxwell simulations are employed to investigate the role of
+kinetic effects in a two-dimensional turbulent multi-ion plasma, composed of
+protons, alpha particles and fluid electrons. In the typical conditions of the
+solar-wind environment, and in situations of decaying turbulence, the numerical
+results show that the velocity distribution functions of both ion species
+depart from the typical configuration of thermal equilibrium. These
+non-Maxwellian features are quantified through the statistical analysis of the
+temperature anisotropy, for both protons and alpha particles, in the reference
+frame given by the local magnetic field. Anisotropy is found to be higher in
+regions of high magnetic stress. Both ion species manifest a preferentially
+perpendicular heating, although the anisotropy is more pronounced for the alpha
+particles, according with solar wind observations. Anisotropy of the alpha
+particle, moreover, is correlated to the proton anisotropy, and also depends on
+the local differential flow between the two species. Evident distortions of the
+particle distribution functions are present, with the production of bumps along
+the direction of the local magnetic field. The physical phenomenology recovered
+in these numerical simulations reproduces very common measurements in the
+turbulent solar wind, suggesting that the multi-ion Vlasov model constitutes a
+valid approach to the understanding of the nature of complex kinetic effects in
+astrophysical plasmas.",1207.5379v1
+2012-09-04,On the orbital and internal evolution of cluster galaxies,"Galaxies inhabiting a cluster environment experience significant evolution in
+their orbital motions throughout time; this is accompanied by changes in the
+anisotropy parameter, measuring the relative importance of radial and
+tangential motions for a given class of objects. Along with orbital changes,
+galaxies in clusters are well known to undergo severe alteration in their
+hot/cold gas content and star formation properties. Understanding the link
+between the changes in the internal properties of galaxies and their orbital
+motion is of crucial importance in the study of galaxy evolution, as it could
+unveil the primary mechanism responsible for its environmental dependence. Do
+the changes in the internal properties happen in parallel with those in the
+orbital motion? Or are the orbital features at the time of infall what
+determines the fate of the member galaxies? Alternatively: are the properties
+of galaxies at a given time related to the coeval orbital anisotropy or are
+they better related to the anisotropy at infall? In order to answer these
+questions, we studied the orbital evolution of different galaxy populations in
+the semi-analytic models of Guo et al. (2011) applied on to the Millennium
+Simulation. For each class of objects, characterised by different internal
+properties (such as age, star formation rate and colour), we studied the
+anisotropy profile at redshift zero and its evolution by tracing the
+progenitors back in time. We conclude that the orbital properties at infall
+strongly influence the subsequent evolution of the internal features of
+galaxies and that the overall anisotropy of the galaxy population tends to
+increase with time.",1209.0586v1
+2012-10-12,A search for anisotropy in the arrival directions of ultra high energy cosmic rays recorded at the Pierre Auger Observatory,"Observations of cosmic ray arrival directions made with the Pierre Auger
+Observatory have previously provided evidence of anisotropy at the 99% CL using
+the correlation of ultra high energy cosmic rays (UHECRs) with objects drawn
+from the Veron-Cetty Veron catalog. In this paper we report on the use of three
+catalog independent methods to search for anisotropy. The 2pt-L, 2pt+ and 3pt
+methods, each giving a different measure of self-clustering in arrival
+directions, were tested on mock cosmic ray data sets to study the impacts of
+sample size and magnetic smearing on their results, accounting for both angular
+and energy resolutions. If the sources of UHECRs follow the same large scale
+structure as ordinary galaxies in the local Universe and if UHECRs are
+deflected no more than a few degrees, a study of mock maps suggests that these
+three methods can efficiently respond to the resulting anisotropy with a
+P-value = 1.0% or smaller with data sets as few as 100 events. Using data taken
+from January 1, 2004 to July 31, 2010 we examined the 20, 30,..., 110 highest
+energy events with a corresponding minimum energy threshold of about 49.3 EeV.
+The minimum P-values found were 13.5% using the 2pt-L method, 1.0% using the
+2pt+ method and 1.1% using the 3pt method for the highest 100 energy events. In
+view of the multiple (correlated) scans performed on the data set, these
+catalog-independent methods do not yield strong evidence of anisotropy in the
+highest energy cosmic rays.",1210.3602v1
+2012-12-10,Proton temperature anisotropy and magnetic reconnection in the solar wind: effects of kinetic instabilities on current sheet stability,"We investigate the role of kinetic instabilities driven by a proton
+anisotropy on the onset of magnetic reconnection by means of 2-D hybrid
+simulations. The collisionless tearing of a current sheet is studied in the
+presence of a proton temperature anisotropy in the surrounding plasma. Our
+results confirm that anisotropic protons within the current sheet region can
+significantly enhance/stabilize the tearing instability of the current.
+Moreover, fluctuations associated to linear instabilities excited by large
+proton temperature anisotropies can significantly influence the stability of
+the plasma and perturb the current sheets, triggering the tearing instability.
+We find that such a complex coupling leads to a faster tearing evolution in a
+regime with larger perpendicular temperature when an ion-cyclotron instability
+is generated by the anisotropic proton distribution functions. On the contrary,
+in the presence of the opposite anisotropy, fire hose fluctuations excited by
+the unstable background protons with larger parallel temperature are not able
+to efficiently destabilize the current sheets, which remain stable for a long
+time after fire hose saturation. We discuss possible influences of this novel
+coupling on the solar wind and heliospheric plasma dynamics.",1212.2101v1
+2013-04-11,Sign-reversal of the in-plane resistivity anisotropy in iron pnictides,"The concept of an electronically-driven breaking of the rotational symmetry
+of a crystal, without involving magnetic order, has found experimental support
+in several systems, from semiconductor heterostructures and ruthenates, to
+cuprate and iron-pnictide superconductors. In the pnictide BaFe$_{2}$As$_{2}$,
+such an ""electronic nematic state"" appears above the magnetic transition dome,
+over a temperature range that can be controlled by external strain. Here, by
+measuring the in-plane resistivity anisotropy, we probe the electronic
+anisotropy of this material over the entire nematic/magnetic dome, whose end
+points coincide with the optimal superconducting transition temperatures.
+Counter-intuitively, we find that, unlike other materials, the resistivity
+anisotropy in BaFe$_{2}$As$_{2}$ changes sign across the doping phase diagram,
+even though the signs of the magnetic, nematic, and orthorhombic order
+parameters are kept fixed. This behavior is explained by the Fermi surface
+reconstruction in the magnetic phase and spin-fluctuation scattering in the
+nematic phase. The unique behavior of the transport anisotropy unveils that the
+primary role is played by magnetic scattering in the normal state transport
+properties of the iron pnictides, suggesting a close connection between
+magnetism, nematicity, and unconventional superconductivity.",1304.3490v1
+2013-05-04,Effect of perpendicular uniaxial anisotropy on the annihilation fields of magnetic vortices,"The magnetic vortex structure, that is present in several nanoscopic systems,
+is stable and can be manipulated through the application of a magnetic field or
+a spin polarized current. The size and shape of the core are strongly affected
+by the anisotropy, however its role on the core behavior has not yet been
+clarified. In the present work we investigate the influence of a perpendicular
+anisotropy on the annihilation and shape of magnetic vortex cores in permalloy
+disks. We have used both micromagnetic simulations with the OOMMF code, and an
+analytical model that assumes that the shape of the core does not change during
+the hysteresis cycle, known as the rigid core model, to calculate the
+annihilation fields. In both cases we found that the annihilation fields
+decrease with increasing perpendicular anisotropy for almost all the structures
+investigated. The simulations show that for increasing anisotropy or dot
+thickness, or both, the vortex core profile changes its shape, becoming
+elongated. For every dot thickness, this change does not depend on the dot
+radius, but on the relative distance of the core from the center of the dot.",1305.0942v2
+2013-05-19,Self-Similar Anisotropic Texture Analysis: the Hyperbolic Wavelet Transform Contribution,"Textures in images can often be well modeled using self-similar processes
+while they may at the same time display anisotropy. The present contribution
+thus aims at studying jointly selfsimilarity and anisotropy by focusing on a
+specific classical class of Gaussian anisotropic selfsimilar processes. It will
+first be shown that accurate joint estimates of the anisotropy and
+selfsimilarity parameters are performed by replacing the standard 2D-discrete
+wavelet transform by the hyperbolic wavelet transform, which permits the use of
+different dilation factors along the horizontal and vertical axis. Defining
+anisotropy requires a reference direction that needs not a priori match the
+horizontal and vertical axes according to which the images are digitized, this
+discrepancy defines a rotation angle. Second, we show that this rotation angle
+can be jointly estimated. Third, a non parametric bootstrap based procedure is
+described, that provides confidence interval in addition to the estimates
+themselves and enables to construct an isotropy test procedure, that can be
+applied to a single texture image. Fourth, the robustness and versatility of
+the proposed analysis is illustrated by being applied to a large variety of
+different isotropic and anisotropic self-similar fields. As an illustration, we
+show that a true anisotropy built-in self-similarity can be disentangled from
+an isotropic self-similarity to which an anisotropic trend has been
+superimposed.",1305.4384v1
+2013-06-11,Bethe ansatz description of edge-localization in the open-boundary XXZ spin chain,"At large values of the anisotropy \Delta, the open-boundary Heisenberg
+spin-1/2 chain has eigenstates displaying localization at the edges. We present
+a Bethe ansatz description of this `edge-locking' phenomenon in the entire
+\Delta>1 region. We focus on the simplest spin sectors, namely the highly
+polarized sectors with only one or two overturned spins, i.e., one-particle and
+two-particle sectors. Edge-locking is associated with pure imaginary solutions
+of the Bethe equations, which are not commonly encountered in periodic chains.
+In the one-particle case, at large anisotropies there are two eigenstates with
+imaginary Bethe momenta, related to localization at the two edges. For any
+finite chain size, one of the two solutions become real as the anisotropy is
+lowered below a certain value. For two particles, a richer scenario is
+observed, with eigenstates having the possibility of both particles locked on
+the same or different edge, one locked and the other free, and both free either
+as single magnons or as bound composites corresponding to `string' solutions.
+For finite chains, some of the edge-locked spins get delocalized at certain
+values of the anisotropy (`exceptional points'), corresponding to imaginary
+solutions becoming real. We characterize these phenomena thoroughly by
+providing analytic expansions of the Bethe momenta for large chains, large
+anisotropy, and near the exceptional points. In the large-chain limit all the
+exceptional points coalesce at the isotropic point (\Delta=1) and edge-locking
+becomes stable in the whole \Delta>1 region.",1306.2666v3
+2013-07-07,Instabilities Driven by the Drift and Temperature Anisotropy of Alpha Particles in the Solar Wind,"We investigate the conditions under which parallel-propagating
+Alfv\'en/ion-cyclotron (A/IC) waves and fast-magnetosonic/whistler (FM/W) waves
+are driven unstable by the differential flow and temperature anisotropy of
+alpha particles in the solar wind. We focus on the limit in which $w_{\parallel
+\alpha} \gtrsim 0.25 v_{\mathrm A}$, where $w_{\parallel \alpha} $ is the
+parallel alpha-particle thermal speed and $v_{\mathrm A}$ is the Alfv\'en
+speed. We derive analytic expressions for the instability thresholds of these
+waves, which show, e.g., how the minimum unstable alpha-particle beam speed
+depends upon $w_{\parallel \alpha}/v_{\mathrm A}$, the degree of alpha-particle
+temperature anisotropy, and the alpha-to-proton temperature ratio. We validate
+our analytical results using numerical solutions to the full hot-plasma
+dispersion relation. Consistent with previous work, we find that temperature
+anisotropy allows A/IC waves and FM/W waves to become unstable at significantly
+lower values of the alpha-particle beam speed $U_\alpha$ than in the
+isotropic-temperature case. Likewise, differential flow lowers the minimum
+temperature anisotropy needed to excite A/IC or FM/W waves relative to the case
+in which $U_\alpha =0$. We discuss the relevance of our results to alpha
+particles in the solar wind near 1 AU.",1307.1823v2
+2013-08-06,Anisotropic Lyman-alpha Emission,"As a result of resonant scatterings off hydrogen atoms, Lyman-alpha (Lya)
+emission from star-forming galaxies provides a probe of the (hardly isotropic)
+neutral gas environment around them. We study the effect of the environmental
+anisotropy on the observed Lya emission by performing radiative transfer
+calculations for models of neutral hydrogen clouds with prescriptions of
+spatial and kinematic anisotropies. The environmental anisotropy leads to
+corresponding anisotropy in the Lya flux and spectral properties and induces
+correlations among them. The Lya flux (or observed luminosity) depends on the
+viewing angle and shows an approximate correlation with the initial Lya optical
+depth in the viewing direction relative to those in all other directions. The
+distribution of Lya flux from a set of randomly oriented clouds is skewed to
+high values, providing a natural contribution to the Lya equivalent width (EW)
+distribution seen in observation. A narrower EW distribution is found at a
+larger peak offset of the Lya line, similar to the trend suggested in
+observation. The peak offset appears to correlate with the line shape (full
+width at half maximum and asymmetry), pointing to a possibility of using Lya
+line features alone to determine the systemic redshifts of galaxies. The study
+suggests that anisotropies in the spatial and kinematic distributions of
+neutral hydrogen can be an important ingredient in shaping the observed
+properties of Lya emission from star-forming galaxies. We discuss the
+implications of using Lya emission to probe the circumgalactic and
+intergalactic environments of galaxies.",1308.1405v2
+2014-02-19,"Solar wind protons at 1 AU: trends and bounds, constraints and correlations","The proton temperature anisotropy in the solar wind exhibits apparent bounds
+which are compatible with the theoretical constraints imposed by
+temperature-anisotropy driven kinetic instabilities. Recent statistical
+analyses based on conditional averaging indicate that near these theoretical
+constraints the solar wind protons have typically enhanced temperatures and a
+weaker collisionality. Here we carefully analyze the solar wind data and show
+that these results are a consequence of superposition of multiple correlations
+in the solar wind, namely, they mostly result from the correlation between the
+proton temperature and the solar wind velocity and from the superimposed
+anti-correlation between the proton temperature anisotropy and the proton
+parallel beta in the fast solar wind. Colder and more collisional data are
+distributed around temperature isotropy whereas hotter and less collisional
+data have a wider range of the temperature anisotropy anti-correlated with the
+proton parallel beta with signatures of constraints owing to the
+temperature-anisotropy driven instabilities. However, most of the hot and
+weakly collisional data, including the hottest and least collisional ones, lies
+far from the marginal stability regions. Consequently, we conclude that there
+is no clear relation between the enhanced temperatures and instability
+constraints and that the conditional averaging used for these analyses must be
+used carefully and need to be well tested.",1402.4611v1
+2014-05-19,Peculiar motion of the solar system derived from a dipole anisotropy in the redshift distribution of distant quasars,"An observer stationary with respect to comoving coordinates of the expanding
+universe should find the redshift distribution to be isotropic. However, a
+peculiar motion of the observer would introduce a dipole anisotropy in the
+observed redshift distribution. Conversely, a dipole anisotropy in observed
+redshift distribution could be exploited to infer our peculiar motion, or
+rather of our solar system. We determine here our peculiar velocity by studying
+the dipole anisotropy in the redshift distribution of a large sample of
+quasars. The magnitude of the peculiar velocity thus determined turns out to be
+$2350\pm280$ km s$^{-1}$, not only much larger than 370 km s$^{-1}$ determined
+from the dipole anisotropy in the Cosmic Microwave Background Radiation (CMBR),
+but also nearly in an opposite direction. Such large values for peculiar
+velocity have been found in a couple of radio surveys too, but with a direction
+along the CMBR dipole. Large genuine differences in the inferred motion,
+whether in magnitude or direction, are rather disconcerting since a solar
+peculiar velocity should not depend upon the method of its determination. Such
+discordant dipoles imply perhaps an anisotropic universe, violating the
+cosmological principle, a cornerstone of the modern cosmology.",1405.4796v4
+2014-06-13,Kinematical fingerprints of star cluster early dynamical evolution,"We study the effects of the external tidal field on the violent relaxation
+phase of star clusters dynamical evolution, with particular attention to the
+kinematical properties of the equilibrium configurations emerging at the end of
+this phase.We show that star clusters undergoing the process of violent
+relaxation in the tidal field of their host galaxy can acquire significant
+internal differential rotation and are characterized by a distinctive radial
+variation of the velocity anisotropy. These kinematical properties are the
+result of the symmetry breaking introduced by the external tidal field in the
+collapse phase and of the action of the Coriolis force on the orbit of the
+stars. The resulting equilibrium configurations are characterized by
+differential rotation, with a peak located between one and two half-mass radii.
+As for the anisotropy, similar to clusters evolving in isolation, the systems
+explored in this Letter are characterized by an inner isotropic core, followed
+by a region of increasing radial anisotropy. However for systems evolving in an
+external tidal field the degree of radial anisotropy reaches a maximum in the
+cluster intermediate regions and then progressively decreases, with the cluster
+outermost regions being characterized by isotropy or a mild tangential
+anisotropy. Young or old but less-relaxed dynamically young star clusters may
+keep memory of these kinematical fingerprints of their early dynamical
+evolution.",1406.3634v1
+2014-10-09,A CMB Gibbs sampler for localized secondary anisotropies,"As well as primary fluctuations, CMB temperature maps contain a wealth of
+additional information in the form of secondary anisotropies. Secondary effects
+that can be identified with individual objects, such as the thermal and kinetic
+Sunyaev-Zel'dovich (SZ) effects due to galaxy clusters, are difficult to
+unambiguously disentangle from foreground contamination and the primary CMB
+however. We develop a Bayesian formalism for rigorously characterising
+anisotropies that are localised on the sky, taking the TSZ and KSZ effects as
+an example. Using a Gibbs sampling scheme, we are able to efficiently sample
+from the joint posterior distribution for a multi-component model of the sky
+with many thousands of correlated physical parameters. The posterior can then
+be exactly marginalised to estimate properties of the secondary anisotropies,
+fully taking into account degeneracies with the other signals in the CMB map.
+We show that this method is computationally tractable using a simple
+implementation based on the existing Commander component separation code, and
+also discuss how other types of secondary anisotropy can be accommodated within
+our framework.",1410.2544v2
+2014-11-23,Slowly Rotating Anisotropic Neutron Stars in General Relativity and Scalar-Tensor Theory,"Some models (such as the Skyrme model, a low-energy effective field theory
+for QCD) suggest that the high-density matter prevailing in neutron star
+interiors may be significantly anisotropic. Anisotropy is known to affect the
+bulk properties of nonrotating neutron stars in General Relativity. In this
+paper we study the effects of anisotropy on slowly rotating stars in General
+Relativity. We also consider one of the most popular extensions of Einstein's
+theory, namely scalar-tensor theories allowing for spontaneous scalarization (a
+phase transition similar to spontaneous magnetization in ferromagnetic
+materials). Anisotropy affects the moment of inertia of neutron stars (a
+quantity that could potentially be measured in binary pulsar systems) in both
+theories. We find that the effects of scalarization increase (decrease) when
+the tangential pressure is bigger (smaller) than the radial pressure, and we
+present a simple criterion to determine the onset of scalarization by
+linearizing the scalar-field equation. Our calculations suggest that binary
+pulsar observations may constrain the degree of anisotropy or even, more
+optimistically, provide evidence for anisotropy in neutron star cores.",1411.6286v3
+2015-01-16,Direct measurement of the magnetic anisotropy field in Mn--Ga and Mn--Co--Ga Heusler films,"The static and dynamic magnetic properties of tetragonally distorted Mn--Ga
+based alloys were investigated. Static properties are determined in magnetic
+fields up to 6.5~T using SQUID magnetometry. For the pure Mn$_{1.6}$Ga film,
+the saturation magnetisation is 0.36~MA/m and the coercivity is 0.29~T. Partial
+substitution of Mn by Co results in Mn$_{2.6}$Co$_{0.3}$Ga$_{1.1}$. The
+saturation magnetisation of those films drops to 0.2~MA/m and the coercivity is
+increased to 1~T.
+  Time-resolved magneto-optical Kerr effect (TR-MOKE) is used to probe the
+high-frequency dynamics of Mn--Ga. The ferromagnetic resonance frequency
+extrapolated to zero-field is found to be 125~GHz with a Gilbert damping,
+$\alpha$, of 0.019. The anisotropy field is determined from both SQUID and
+TR-MOKE to be 4.5~T, corresponding to an effective anisotropy density of
+0.81~MJ/m$^3$.
+  Given the large anisotropy field of the Mn$_{2.6}$Co$_{0.3}$Ga$_{1.1}$ film,
+pulsed magnetic fields up to 60~T are used to determine the field strength
+required to saturate the film in the plane. For this, the extraordinary Hall
+effect was employed as a probe of the local magnetisation. By integrating the
+reconstructed in--plane magnetisation curve, the effective anisotropy energy
+density for Mn$_{2.6}$Co$_{0.3}$Ga$_{1.1}$ is determined to be 1.23~MJ/m$^3$.",1501.03973v1
+2015-03-02,Predicted Impacts of Proton Temperature Anisotropy on Solar Wind Turbulence,"Particle velocity distributions measured in the weakly collisional solar wind
+are frequently found to be non-Maxwellian, but how these non-Maxwellian
+distributions impact the physics of plasma turbulence in the solar wind remains
+unanswered. Using numerical solutions of the linear dispersion relation for a
+collisionless plasma with a bi-Maxwellian proton velocity distribution, we
+present a unified framework for the four proton temperature anisotropy
+instabilities, identifying the associated stable eigenmodes, highlighting the
+unstable region of wavevector space, and presenting the properties of the
+growing eigenfunctions. Based on physical intuition gained from this framework,
+we address how the proton temperature anisotropy impacts the nonlinear dynamics
+of the \Alfvenic fluctuations underlying the dominant cascade of energy from
+large to small scales and how the fluctuations driven by proton temperature
+anisotropy instabilities interact nonlinearly with each other and with the
+fluctuations of the large-scale cascade. We find that the nonlinear dynamics of
+the large-scale cascade is insensitive to the proton temperature anisotropy,
+and that the instability-driven fluctuations are unlikely to cause significant
+nonlinear evolution of either the instability-driven fluctuations or the
+turbulent fluctuations of the large-scale cascade.",1503.00695v2
+2015-03-10,In-plane electronic anisotropy in the antiferromagnetic-orthorhombic phase of isovalent-substituted Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$,"We have studied the anisotropy in the in-plane resistivity and the electronic
+structure of isovalent Ru-substituted BaFe$_2$As$_2$ in the
+antiferromagnetic-orthorhombic phase using well-annealed crystals. The
+anisotropy in the residual resistivity component increases in proportional to
+the Ru dopant concentration, as in the case of Co-doped compounds. On the other
+hand, both the residual resistivity and the resistivity anisotropy induced by
+isovalent Ru substitution is found to be one order of magnitude smaller than
+those induced by heterovalent Co substitution. Combined with angle-resolved
+photoemission spectroscopy results, which show almost the same anisotropic band
+structure both for the parent and Ru-substituted compounds, we confirm the
+scenario that the anisotropy in the residual resistivity arises from
+anisotropic impurity scattering in the magneto-structurally ordered phase
+rather than directly from the anisotropic band structure of that phase.",1503.02855v1
+2015-06-29,Influence of interphase anisotropy on lamellar eutectic growth patterns,"It is well documented in many experiments that crystallographic effects play
+an important role in the generation of two-phase patterns during the
+solidification of eutectic alloys. In particular, in lamellar composites, large
+patches of perfectly aligned lamellae are frequently observed. Moreover, the
+growth direction of the lamellae often markedly differs from the direction of
+the temperature gradient (the lamellae are tilted with respect to the main
+growth direction). Both of these effects cannot be explained either by the
+standard theory or the available numerical models of eutectic growth, which all
+assume the interfaces to be isotropic. We have developed a phase-field model in
+which the anisotropy of each interface (solid-liquid and solid-solid) can be
+separately controlled, and we have investigated the effect of interface
+anisotropy on the growth dynamics. We have found that anisotropy of the
+solid-solid interphase boundary free energy dramatically alters the growth
+dynamics. Tilted lamellae result from the modified equilibrium condition at the
+triple lines, in good agreement with a theoretical conjecture proposed
+recently. In three dimensions, the interphase boundaries tend to align with
+directions of minimal energy. We have also performed simulations in which two
+grains with different anisotropies are in competition. In all cases, the grain
+containing the boundaries with the lowest energies was selected after a
+transient. These results shed new light on the selection of growth patterns in
+eutectic solidification.",1506.08893v1
+2015-10-09,Magnetic anisotropy of polycrystalline high-temperature ferromagnetic Mn$_x$Si$_{1-x}$ ($x\approx0.5$) alloy films,"A set of thin film Mn$_x$Si$_{1-x}$ alloy samples with different manganese
+concentration x = 0.44 - 0.63 grown by the pulsed laser deposition (PLD) method
+onto the Al$_2$O$_3$(0001) substrate was investigated in the temperature range
+4 - 300 K using ferromagnetic resonance (FMR) measurements in the wide range of
+frequencies (f = 7 - 60 GHz) and magnetic fields (H = 0 - 30 kOe). For samples
+with x = 0.52 - 0.55, FMR data show clear evidence of ferromagnetism with high
+Curie temperatures T$_\text{C}$ ~ 300 K. These samples demonstrate complex and
+unusual character of magnetic anisotropy described in the frame of
+phenomenological model as a combination of the essential second order easy
+plane anisotropy contribution and the additional forth order uniaxial
+anisotropy contribution with easy direction normal to the film plane. We
+explain the obtained results by a polycrystalline (mosaic) structure of the
+films caused by the film-substrate lattice mismatch. The existence of extra
+strains at the crystallite boundaries leads to an essential inhomogeneous
+magnetic anisotropy in the film plane.",1510.02634v1
+2015-11-01,RKKY-like contributions to the magnetic anisotropy energy: 3d adatoms on Pt(111) surface,"The magnetic anisotropy energy defines the energy barrier that stabilizes a
+magnetic moment. Utilizing density functional theory based simulations and
+analytical formulations, we establish that this barrier is strongly modified by
+long-range contributions very similar to Frieden oscillations and
+Rudermann-Kittel-Kasuya-Yosida interactions. Thus, oscillations are expected
+and observed, with different decaying factors and highly anisotropic in
+realistic materials, which can switch non-trivially the sign of the magnetic
+anisotropy energy. This behavior is general and for illustration we address
+transition metals adatoms, Cr, Mn, Fe and Co deposited on Pt(111) surface. We
+explain in particular the mechanisms leading to the strong site-dependence of
+the magnetic anisotropy energy observed for Fe adatoms on Pt(111) surface as
+revealed previously via first-principles based simulations and inelastic
+scanning tunneling spectroscopy (A. A. Khajetoorians et al. Phys. Rev. Lett.
+111, 157204 (2013)). The same mechanisms are probably active for the
+site-dependence of the magnetic anisotropy energy obtained for Fe adatoms on Pd
+or Rh(111) surfaces and for Co adatoms on Rh(111) surface (P. Blonski et al.
+Phys. Rev. B 81, 104426 (2010)).",1511.00232v2
+2016-02-10,Orientational ordering of confined hard rods: the effect of shape anisotropy on surface ordering and capillary nematization,"We examine the ordering properties of rectangular hard rods with length L and
+diameter D at a single planar wall and between two parallel hard walls using
+the second-virial density functional theory. The theory is implemented in the
+three-state Zwanzig approximation, where only three mutually perpendicular
+directions are allowed for the orientations of hard rods. The effect of varying
+shape anisotropy is examined at L/D=10, 15 and 20. In contact with a single
+hard wall, the density profiles show planar ordering, damped oscillatory
+behavior, and wall induced surface ordering transition below the coexisting
+isotropic density of bulk isotropic-nematic (I-N) phase transition. Upon
+approaching the coexisting isotropic density, the thickness of nematic film
+diverges logarithmically, i.e. the nematic wetting is complete for any shape
+anisotropy. In the case of confinement between two parallel hard walls, it is
+found that the continuous surface ordering transition depends strongly on the
+distance between confining walls (H) for H<L, while it depends weakly on H for
+H>L. The minimal density at which a surface ordering transition can be realized
+is located at around H~2D for all studied shape anisotropies due to the strong
+interference effect between the two hard walls. The first order I-N phase
+transition of the bulk system becomes surface ordered isotropic (IB)-capillary
+nematic (NB) phase transition in the slit pore. This first order IB-NB
+transition weakens with decreasing pore width and terminates in a critical
+point for all studied shape anisotropies.",1602.03485v1
+2016-03-12,Non-monotonic anisotropy in charge conduction induced by antiferrodistortive transition in metallic SrTiO$_{3}$,"Cubic SrTiO$_{3}$ becomes tetragonal below 105 K. The antiferrodistortive
+(AFD) distortion leads to clockwise and counter-clockwise rotation of adjacent
+TiO$_{6}$ octahedra. This insulator becomes a metal upon the introduction of
+extremely low concentration of n-type dopants. However, signatures of the
+structural phase transition in charge conduction have remained elusive.
+Employing the Montgomery technique, we succeed in resolving the anisotropy of
+charge conductivity induced by the AFD transition, in the presence of different
+types of dopants. We find that the slight lattice distortion ($<6 \times
+10^{-4}$) gives rise to a twenty percent anisotropy in charge conductivity, in
+agreement with the expectations of band calculations. Application of uniaxial
+strain amplifies the detectable anisotropy by disfavoring one of the three
+possible tetragonal domains. In contrast with all other known anisotropic Fermi
+liquids, the anisotropy has opposite signs for elastic and inelastic
+scattering. Increasing the concentration of dopants leads to a drastic shift in
+the temperature of the AFD transition either upward or downward. The latter
+result puts strong constraints on any hypothetical role played by the AFD soft
+mode in the formation of Cooper pairs and the emergence of superconductivity in
+SrTiO$_3$.",1603.03831v2
+2016-02-26,The Electron Temperature and Anisotropy in the Solar Wind. I. Comparison of the Core and Halo Populations,"Estimating the temperature of the solar wind particles and their anisotropies
+is particularly important for understanding the origin of these deviations from
+thermal equilibrium as well as their effects. In the absence of energetic
+events the velocity distribution of electrons reveal a dual structure with a
+thermal (Maxwellian) core and a suprathermal (Kappa) halo. This paper presents
+a detailed observational analysis of these two components, providing
+estimations of their temperatures and temperature anisotropies and decoding any
+potential interdependence that their properties may indicate. The data set used
+in this study includes more than 120$\,$000 the events detected by three
+missions in the ecliptic within an extended range of heliocentric distances
+from 0.3 to over 4~AU. The anti-correlation found for the core and halo
+temperatures is consistent with the radial evolution of the Kappa model,
+clarifying an apparent contradiction in previous observational analysis and
+providing valuable clues about the temperature of the Kappa-distributed
+populations. However, these two components manifest a clear tendency to deviate
+from isotropy in the same direction, that seems to confirm the existence of
+mechanisms with similar effects on both components, e.g., the solar wind
+expansion, or the particle heating by the fluctuations. On the other hand, the
+existence of plasma states with anti-correlated anisotropies of the core and
+halo populations suggests a dynamic interplay of these components, mediated,
+most probably, by the anisotropy-driven instabilities.",1603.08392v1
+2016-05-05,Anisotropy of the monomer random walk in a polymer melt: local-order and connectivity effects,"The random walk of a bonded monomer in a polymer melt is anisotropic due to
+local order and bond connectivity. We investigate both effects by
+molecular-dynamics simulations on melts of fully-flexible linear chains ranging
+from dimers ($M=2$) up to entangled polymers ($M=200$). The corresponding
+atomic liquid is also considered as reference system. To disentangle the
+influence of the local geometry and the bond arrangements, and reveal their
+interplay, we define suitable measures of the anisotropy emphasising either the
+former or the latter aspect. Connectivity anisotropy, as measured by the
+correlation between the initial bond orientation and the direction of the
+subsequent monomer displacement, shows a slight enhancement due to the local
+order at times shorter than the structural relaxation time. At intermediate
+times - when the monomer displacement is comparable to the bond length - a
+pronounced peak and then decays slowly as $t^{-1/2}$, becoming negligible when
+the displacements is as large as about five bond lengths, i.e. about four
+monomer diameters or three Kuhn lengths. Local-geometry anisotropy, as measured
+by the correlation between the initial orientation of a characteristic axis of
+the Voronoi cell and the subsequent monomer dynamics, is affected at shorter
+times than the structural relaxation time by the cage shape with antagonistic
+disturbance by the connectivity. Differently, at longer times, the connectivity
+favours the persistence of the local-geometry anisotropy which vanishes when
+the monomer displacement exceeds the bond length. Our results strongly suggest
+that the sole consideration of the local order is not enough to understand the
+microscopic origin of the rattling amplitude of the trapped monomer in the cage
+of the neighbours.",1605.01568v1
+2016-07-11,Significance of Natural Scene Statistics in Understanding the Anisotropies of Perceptual Filling-in at the Blind Spot,"Psychophysical experiments reveal our horizontal preference in perceptual
+filling-in at the blind spot. On the other hand, vertical preference is
+exhibited in the case of tolerance in filling-in. What causes this anisotropy
+in our perception? Building upon the general notion, that the functional
+properties of the early visual system are shaped by the innate specification as
+well as the statistics of the environment, we reasoned that the anisotropy in
+filling-in could be understood in terms of anisotropy in orientation
+distribution inherent to natural scene statistics. We examined this proposition
+by investigating filling-in of bar stimuli on a Hierarchical Predictive Coding
+model network. In response to bar stimuli, the model network, trained with
+natural images, exhibited anisotropic filling-in performance at the blind spot
+similar to reported in psychophysical experiments i.e. horizontal preference in
+filling-in and vertical preference in tolerance of filling-in. We suggest that
+the over-representation of horizontal contours in the natural scene contribute
+to the observed horizontal superiority while the broader distribution of
+vertical contours contributes to the observed vertical superiority in
+tolerance. These results indicate that natural scene statistics plays a
+significant role in determining the filling-in performance at the blind spot
+and shaping the associated anisotropies.",1607.02865v2
+2016-07-14,Study of velocity centroids based on the theory of fluctuations in position-position-velocity space,"We study possibility of obtaining velocity spectra by studying turbulence in
+an optically thick medium using velocity centroids (VCs).We find that the
+regime of universal, i.e. independent of underlying turbulence statistics,
+fluctuations discovered originally within the velocity channel analysis (VCA)
+carries over to the statistics of VCs. In other words, for large absorptions
+the VC lose their ability to reflect the spectra of turbulence. Combining our
+present study with the earlier studies of centroids in Esquivel & Lazarian, we
+conclude that centroids are applicable for studies subsonic/transsonic
+turbulence for the range of scales that is limited by the absorption effects.
+We also consider VCs based on absorption lines and define the range of their
+applicability. We address the problem of analytical description of spectra and
+anisotropies of fluctuations that are available through studies using VC. We
+obtain spectra and anisotropy of VC fluctuations arising from Alfv\'en, slow
+and fast modes that constitute the compressible MHD cascade to address the
+issue of anisotropy of VC statistics, and show how the VC anisotropy can be
+used to find the media magnetization as well as to identify and separate
+contributions from Alfv\'en, slow and fast modes. Our study demonstrates that
+VCs are complementary to the tools provided by the VCA. In order to study
+turbulent volume for which the resolution of single dish telescopes is
+insufficient, we demonstrate how the studies of anisotropy can be performed
+using interferometers.",1607.04316v1
+2016-09-20,Magnetic anisotropy and the phase diagram of chiral MnSb2O6,"The magnetic phase diagram and low-energy magnon excitations of structurally
+and magnetically chiral MnSb2O6 are reported. The specific heat and the static
+magnetization are investigated in magnetic fields up to 9 and 30 T,
+respectively, while the dynamicmagnetic properties are probed by X-band as well
+as tunable high-frequency electron spin-resonance spectroscopy. Below TN = 11.5
+K, we observe antiferromagnetic resonance modes which imply small but finite
+planar anisotropy showing up in a zero-field splitting of 20 GHz. The data are
+well described by means of an easy-plane two-sublattice model with the
+anisotropy field BA = 0.02 T. The exchange field BE = 13 T is obtained from the
+saturation field derived from the pulsed-field magnetization. A crucial role of
+the small anisotropy for the spin structure is reflected by competing
+antiferromagnetic phases appearing, at T = 2 K, in small magnetic fields at BC1
+$\approx$ 0.5 T and BC2 = 0.9 T. We discuss the results in terms of spin
+reorientation and of small magnetic fields favoring helical spin structure over
+the cycloidal ground state which, at B = 0, is stabilized by the planar
+anisotropy. Above TN, short-range magnetic correlations up to >=60 K and
+magnetic entropy changes well above TN reflect the frustrated triangular
+arrangement of Mn2+ ions in MnSb2O6.",1609.06105v1
+2016-11-18,Dipole anisotropy in cosmic electrons and positrons: inspection on local sources,"The cosmic electrons and positrons have been measured with unprecedented
+statistics up to several hundreds GeV, thus permitting to explore the role that
+close single sources can have in shaping the flux at different energies. In the
+present analysis, we consider electrons and positrons in cosmic rays to be
+produced by spallations of hadron fluxes with the interstellar medium, by a
+smooth Supernova Remnant (SNR) population, by all the ATNF catalog pulsars, and
+by few discrete, local SNRs. We test several source models on the $e^++e^-$ and
+$e^+$ AMS-02 flux data. For the configurations compatible with the data, we
+compute the dipole anisotropy in $e^++e^-$, $e^+$, $e^+/e^-$ from single
+sources. Our study includes a dedicated analysis to the Vela SNR. We show that
+Fermi-LAT present data on dipole anisotropy of $e^++e^-$ start to explore some
+of the models for the Vela SNR selected by AMS-02 flux data. We also
+investigate how the observed anisotropy could result from a combination of
+local sources. Our analysis shows that the search of anisotropy in the lepton
+fluxes up to TeV energies can be an interesting tool for the inspection of
+properties of close SNRs, complementary to the high precision flux data.",1611.06237v1
+2017-02-28,Measuring X-ray anisotropy in solar flares. Prospective stereoscopic capabilities of STIX and MiSolFA,"During the next solar maximum, two upcoming space-borne X-ray missions, STIX
+on board Solar Orbiter and MiSolFA, will perform stereoscopic X-ray
+observations of solar flares at two different locations: STIX at 0.28 AU (at
+perihelion) and up to inclinations of $\sim25^{\circ}$, and MiSolFA in a
+low-Earth orbit. The combined observations from these cross-calibrated
+detectors will allow us to infer the electron anisotropy of individual flares
+confidently for the first time. We simulated both instrumental and physical
+effects for STIX and MiSolFA including thermal shielding, background and X-ray
+Compton backscattering (albedo effect) in the solar photosphere. We predict the
+expected number of observable flares available for stereoscopic measurements
+during the next solar maximum. We also discuss the range of useful spacecraft
+observation angles for the challenging case of close-to-isotropic flare
+anisotropy. The simulated results show that STIX and MiSolFA will be capable of
+detecting low levels of flare anisotropy, for M1-class or stronger flares, even
+with a relatively small spacecraft angular separation of 20-30{\deg}. Both
+instruments will directly measure the flare X-ray anisotropy of about 40 M- and
+X-class solar flares during the next solar maximum. Near-future stereoscopic
+observations with Solar Orbiter/STIX and MiSolFA will help distinguishing
+between competing flare-acceleration mechanisms, and provide essential
+constraints regarding collisional and non-collisional transport processes
+occurring in the flaring atmosphere for individual solar flares.",1702.08795v2
+2017-03-12,GdRh$_2$Si$_2$: An exemplary tetragonal system for antiferromagnetic order with weak in-plane anisotropy,"The anisotropy of magnetic properties commonly is introduced in textbooks
+using the case of an antiferromagnetic system with Ising type anisotropy. This
+model presents huge anisotropic magnetization and a pronounced metamagnetic
+transition and is well-known and well-documented both, in experiments and
+theory. In contrast, the case of an antiferromagnetic $X$-$Y$ system with weak
+in-plane anisotropy is only poorly documented. We studied the anisotropic
+magnetization of the compound GdRh$_2$Si$_2$ and found that it is a perfect
+model system for such a weak-anisotropy setting because the Gd$^{3+}$ ions in
+GdRh$_2$Si$_2$ have a pure spin moment of S=7/2 which orders in a simple AFM
+structure with ${\bf Q} = (001)$. We observed experimentally in $M(B)$ a
+continuous spin-flop transition and domain effects for field applied along the
+$[100]$- and the $[110]$-direction, respectively. We applied a mean field model
+for the free energy to describe our data and combine it with an Ising chain
+model to account for domain effects. Our calculations reproduce the
+experimental data very well. In addition, we performed magnetic X-ray
+scattering and X-ray magnetic circular dichroism measurements, which confirm
+the AFM propagation vector to be ${\bf Q} = (001)$ and indicate the absence of
+polarization on the rhodium atoms.",1703.04114v1
+2017-06-04,The uncertainty of local background magnetic field orientation in anisotropic plasma turbulence,"In order to resolve and characterize anisotropy in turbulent plasma flows a
+proper estimation of the background magnetic field is crucially important.
+Various approaches to calculate the background magnetic fields, ranging from
+local fields to globally averaged fields, are commonly used in the analysis of
+turbulent data. Here we investigate how the uncertainty in the orientation of a
+scale dependent background magnetic field influences the ability to resolve
+anisotropy. Therefore we introduce a quantitative measure, the angle
+uncertainty, which characterizes the uncertainty of the orientation of the
+background magnetic field which turbulent structures are exposed to. The angle
+uncertainty can be used as a condition to estimate the ability to resolve
+anisotropy with certain accuracy. We apply our description to resolve spectral
+anisotropy in fast solar wind data. We show that if the angle uncertainty grows
+too large, the power of the turbulent fluctuations is attributed to false local
+magnetic field angles, which may lead to an incorrect estimation of spectral
+indices. In our results an apparent robustness of the spectral anisotropy to
+false local magnetic field angles is observed, which can be explained by a
+stronger increase of power for lower frequencies when the scale of the local
+magnetic field is increased. The frequency dependent angle uncertainty is a
+measure which can be applied to any turbulent system.",1706.01126v1
+2017-07-03,Searching for a cosmological preferred direction with 147 rotationally supported galaxies,"It is well known that the Milgrom's MOND (modified Newtonian dynamics)
+explains well the mass discrepancy problem in galaxy rotation curves. The MOND
+predicts a universal acceleration scale below which the Newtonian dynamics is
+invalid yet. The universal acceleration scale we got from the SPARC dataset is
+$g_{\dag}=1.02\times10^{-10} \rm m~s^{-2}$. Milgrom suggested that the
+acceleration scale may be a fingerprint of cosmology on local dynamics and
+related with the Hubble constant $g_{\dag}\sim cH_0$. In this paper, we use the
+hemisphere comparison method with the SPARC dataset to investigate the spatial
+anisotropy on the acceleration scale. We find that the hemisphere of the
+maximum acceleration scale is in the direction $(l,b) =
+({175.5^\circ}^{+6^\circ}_{-10^\circ}, {-6.5^\circ}^{+8^\circ}_{-3^\circ})$
+with $g_{\dag,max}=1.10\times10^{-10} \rm m~s^{-2}$, while the hemisphere of
+the minimum acceleration scale is in the opposite direction $(l,b) =
+({355.5^\circ}^{+6^\circ}_{-10^\circ}, {6.5^\circ}^{+3^\circ}_{-8^\circ})$ with
+$g_{\dag,min}=0.76\times10^{-10} \rm m~s^{-2}$. The maximum anisotropy level
+reaches up to $0.37\pm0.04$. Robust tests present that such a level of
+anisotropy can't be reproduced by a statistically isotropic data. In addition,
+we show that the spatial anisotropy on the acceleration scale has little
+correlation with the non-uniform distribution of the SPARC data points in sky.
+We also find that the maximum anisotropy direction is close with other
+cosmological preferred directions, especially the direction of the ""Australia
+dipole"" for the fine structure constant.",1707.00417v1
+2017-08-18,Skyrmion robustness in non-centrosymmetric magnets with axial symmetry: The role of anisotropy and tilted magnetic fields,"We investigate the stability of N\'eel skyrmions against tilted magnetic
+fields, in polar magnets with uniaxial anisotropy ranging from easy-plane to
+easy-axis type. We construct the corresponding phase diagrams and investigate
+the internal structure of skewed skyrmions with displaced cores. We find that
+moderate easy-plane anisotropy increases the stability range of N\'eel
+skyrmions for fields along the symmetry axis, while moderate easy-axis
+anisotropy enhances their robustness against tilted magnetic fields. We stress
+that the direction, along which the skyrmion cores are shifted, depends on the
+symmetry of the underlying crystal lattice. The cores of N\'eel skyrmions,
+realized in polar magnets with C$_{nv}$ symmetry, are displaced either along or
+opposite to the off-axis (in-plane) component of the magnetic field depending
+on the rotation sense of the magnetization, dictated by the sign of the
+Dzyaloshinskii constant. The core shift of antiskyrmions, present in chiral
+magnets with D$_{2d}$ symmetry, depends on the in-plane orientation of the
+magnetic field and can be parallel, anti-parallel, or perpendicular to it. We
+argue that the role of anisotropy in magnets with axially symmetric crystal
+structure is different from that in cubic helimagnets. Our results can be
+applied to address recent experiments on polar magnets with C$_{3v}$ symmetry,
+GaV$_4$S$_8$ and GaV$_4$Se$_8$.",1708.05505v1
+2017-10-16,Anisotropies of Ultra-high Energy Cosmic Rays Dominated by a Single Source in the Presence of Deflections,"This work presents a scenario of ultra-high energy cosmic ray source
+distribution where a nearby source is solely responsible for the anisotropies
+in arrival directions of cosmic rays while the rest of the sources contribute
+only isotropically. An analytical approach focused on large-scale anisotropies,
+which are influenced by deflections in a Kolmogorov-type turbulent magnetic
+field, is employed to provide more general results. When the recent Pierre
+Auger Observatory angular power spectrum above 8 EeV is used the restricted
+model gives, under the assumption of the small angle approximation, a solution
+where the RMS deflection with respect to the line of sight is $\alpha_{\rm rms}
+= \left(50^{+11}_{-10}\right)^\circ$, while the relative flux from the single
+source $\eta=0.03\pm 0.01$. Furthermore, the solution can be translated into
+constraints on the source distance, luminosity, and extra-galactic magnetic
+field strength. For Centaurus A and the Virgo cluster the required relation
+between the coherence length and the RMS magnetic field strength is obtained: a
+coherence length of $~\sim 100\,\mathrm{kpc}$ would imply the RMS field
+strength around $1\,\mathrm{nG}$ for iron dominated and above $10\,\mathrm{nG}$
+for proton dominated composition. We also performed trajectory simulations with
+our publicly available code CRPropa to show that our analytical model can serve
+as a good approximation as long as the deflections in cosmic magnetic fields
+can be described as a random walk. The simulations showed that generally
+structured fields tend to suppress large-scale anisotropies, especially the
+dipole, compared to anisotropies at smaller scales described by higher
+multipoles.",1710.05517v3
+2017-11-08,Polarization of Sunyaev-Zeldovich signal due to electron pressure anisotropy in galaxy clusters,"We describe polarization of the Sunyaev-Zel'dovich (SZ) effect associated
+with electron pressure anisotropy likely present in the intracluster medium
+(ICM). The ICM is an astrophysical example of a weakly collisional plasma where
+the Larmor frequencies of charged particles greatly exceed their collision
+frequencies. This permits formation of pressure anisotropies, driven by
+evolving magnetic fields via adiabatic invariance, or by heat fluxes. SZ
+polarization arises in the process of Compton scattering of the cosmic
+microwave background (CMB) photons off the thermal ICM electrons due to the
+difference in the characteristic thermal velocities of the electrons along two
+mutually orthogonal directions in the sky plane. The signal scales linearly
+with the optical depth of the region containing large-scale correlated
+anisotropy, and with the degree of anisotropy itself. It has the same spectral
+dependence as the polarization induced by cluster motion with respect to the
+CMB frame (kinematic SZ effect polarization), but can be distinguished by its
+spatial pattern. { For the illustrative case of a galaxy cluster with a cold
+front, where electron transport is mediated by Coulomb collisions, we estimate
+the CMB polarization degree at the level of 10$^{-8}$ ($\sim 10$ nK). An
+increase of the effective electron collisionality due to plasma instabilities
+will reduce the effect. Such polarization, therefore, may be an independent
+probe of the electron collisionality in the ICM, which is one of the key
+properties of a high-$\beta$ weakly collisional plasma from the point of view
+of both astrophysics and plasma theory.",1711.03084v1
+2017-11-25,Tilted vortex cores and superconducting gap anisotropy in 2H-NbSe2,"Superconducting vortex cores have been extensively studied for magnetic
+fields applied perpendicular to the surface by mapping the density of states
+(DOS) through Scanning Tunneling Microscopy (STM). Vortex core shapes are often
+linked to the superconducting gap anisotropy---quasiparticle states inside
+vortex cores extend along directions where the superconducting gap is smallest.
+The superconductor 2H-NbSe$_2$ crystallizes in a hexagonal structure and
+vortices give DOS maps with a sixfold star shape for magnetic fields
+perpendicular to the surface and the hexagonal plane. This has been associated
+to a hexagonal gap anisotropy located on quasi two-dimensional Fermi surface
+tubes oriented along the $c$ axis. The gap anisotropy in another,
+three-dimensional, pocket is unknown. However, the latter dominates the STM
+tunneling conductance. Here we measure DOS in magnetic fields parallel to the
+surface and perpendicular to the $c$ axis. We find patterns of stripes due to
+in-plane vortex cores running nearly parallel to the surface. The patterns
+change with the in-plane direction of the magnetic field, suggesting that the
+sixfold gap anisotropy is present over the whole Fermi surface. Due to a slight
+misalignment between the vector of the magnetic field and the surface, our
+images also show outgoing vortices. Their shape is successfully compared to
+detailed calculations of vortex cores in tilted fields. Their features merge
+with the patterns due to in plane vortices, suggesting that they exit at an
+angle with the surface. Measuring the DOS of vortex cores in highly tilted
+magnetic fields with STM can thus be used to study the superconducting gap
+structure.",1711.09269v1
+2018-05-01,Black Arsenic: A Layered Semiconductor with Extreme in-plane Anisotropy,"Two-dimensional (2D) layered materials emerge in recent years as a new
+platform to host novel electronic, optical or excitonic physics and develop
+unprecedented nanoelectronic and energy applications. By definition, these
+materials are strongly anisotropic between within the basal plane and cross the
+plane. The structural and property anisotropies inside their basal plane,
+however, are much less investigated. Herein, we report a rare chemical form of
+arsenic, called black-arsenic (b-As), as an extremely anisotropic layered
+semiconductor. We have performed systematic characterization on the structural,
+electronic, thermal and electrical properties of b-As single crystals, with
+particular focus on its anisotropies along two in-plane principle axes,
+armchair (AC) and zigzag (ZZ). Our analysis shows that b-As exhibits higher or
+comparable electronic, thermal and electric transport anisotropies between the
+AC and ZZ directions than any other known 2D crystals. Such extreme in-plane
+anisotropies are able to potentially implement novel ideas for scientific
+research and device applications.",1805.00418v1
+2018-05-13,Pressure-induced spin reorientation transition in layered ferromagnetic insulator Cr2Ge2Te6,"Anisotropic magnetoresistance (AMR) of Cr2Ge2Te6 (CGT), a layered
+ferromagnetic insulator, is investigated under an applied hydrostatic pressure
+up to 2 GPa. The easy axis direction of the magnetization is inferred from the
+AMR saturation feature in the presence and absence of the applied pressure. At
+zero applied pressure, the easy axis is along the c-direction or perpendicular
+to the layer. Upon application of a hydrostatic pressure>1 GPa, the uniaxial
+anisotropy switches to easy-plane anisotropy which drives the equilibrium
+magnetization from the c-axis to the ab-plane at zero magnetic field, which
+amounts to a giant magnetic anisotropy energy change (>100%). As the
+temperature is increased across the Curie temperature, the characteristic AMR
+effect gradually decreases and disappears. Our first-principles calculations
+confirm the giant magnetic anisotropy energy change with moderate pressure and
+assign its origin to the increased off-site spin-orbit interaction of Te atoms
+due to a shorter Cr-Te distance. Such a pressure-induced spin reorientation
+transition is very rare in three-dimensional ferromagnets, but it may be common
+to other layered ferromagnets with similar crystal structures to CGT, and
+therefore offers a unique way to control magnetic anisotropy.",1805.04937v1
+2018-05-23,Detection and Removal of B-mode Dust Foregrounds with Signatures of Statistical Anisotropy,"Searches for inflationary gravitational wave signals in the CMB B-mode
+polarisation are expected to reach unprecedented power over the next decade. A
+major difficulty in these ongoing searches is that galactic foregrounds such as
+dust can easily mimic inflationary signals. Though typically foregrounds are
+separated from primordial signals using the foregrounds' different frequency
+dependence, in this paper we investigate instead the extent to which the
+galactic dust B-modes' statistical anisotropy can be used to distinguish them
+from inflationary B-modes, building on the work of Kamionkowski and Kovetz
+(2014). In our work, we extend existing anisotropy estimators and apply them to
+simulations of polarised dust to forecast their performance for future
+experiments. Considering the application of this method as a null-test for dust
+contamination to CMB-S4, we find that we can detect residual dust levels
+corresponding to $r\sim0.001$ at $2\sigma$, which implies that statistical
+anisotropy estimators will be a powerful diagnostic for foreground residuals
+(though our results show some dependence on the dust simulation used). Finally,
+considering applications beyond a simple null test, we demonstrate how
+anisotropy statistics can be used to construct an estimate of the dust B-mode
+map, which could potentially be used to clean the B-mode sky.",1805.09177v2
+2018-06-07,Null Signal for the Cosmic Anisotropy in the Pantheon Supernovae Data,"The cosmological principle assumes that the universe is homogeneous and
+isotropic on cosmic scales. There exist many works testing the cosmic
+homogeneity and/or the cosmic isotropy of the universe in the literature. In
+fact, some observational hints of the cosmic anisotropy have been claimed.
+However, we note that the paucity of the data considered in the literature
+might be responsible for the `found' cosmic anisotropy. So, it might disappear
+in a large enough sample. Very recently, the Pantheon sample consisting of 1048
+type Ia supernovae (SNIa) has been released, which is the largest
+spectroscopically confirmed SNIa sample to date. In the present work, we test
+the cosmic anisotropy in the Pantheon SNIa sample by using three methods, and
+hence the results from different methods can be cross-checked. All the results
+obtained by using the hemisphere comparison (HC) method, the dipole fitting
+(DF) method and HEALPix suggest that no evidence for the cosmic anisotropy is
+found in the Pantheon SNIa sample.",1806.02773v3
+2018-07-29,"A family of high-temperature ferromagnetic monolayers with locked spin-dichroism-mobility anisotropy: MnNX and CrCX (X=Cl, Br, I; C=S, Se, Te)","Two-dimensional magnets have received increasing attention since Cr2Ge2Te6
+and CrI3 were experimentally exfoliated and measured in 2017. Although layered
+ferromagnetic metals were demonstrated at room temperature, a layered
+ferromagnetic semiconductor with high Curie temperature (Tc) is yet to be
+unveiled. Here, we theoretically predicted a family of high Tc ferromagnetic
+monolayers, namely MnNX and CrCX (X=Cl, Br and I; C=S, Se and Te). Their Tc
+values were predicted from over 100 K to near 500 K with Monte Carlo
+simulations using an anisotropic Heisenberg model. Eight members among them
+show semiconducting bandgaps varying from roughly 0.23 to 1.85 eV. These
+semiconducting monolayers also show extremely large anisotropy, i.e. ~101 for
+effective masses and ~102 for carrier mobilities, along the two in-plane
+lattice directions of these layers. Additional orbital anisotropy leads to a
+spin-locked linear dichroism, in different from previously known circular and
+linear dichroisms in layered materials. Together with the mobility anisotropy,
+it offers a spin-, dichroism- and mobility-anisotropy locking. These results
+manifest the potential of this 2D family for both fundamental research and high
+performance spin-dependent electronic and optoelectronic devices.",1807.11000v3
+2018-08-06,Cosmic-Ray Anisotropy from Large Scale Structure and the effect of magnetic horizons,"Motivated by the ~7 % dipole anisotropy in the distribution of ultra-high
+energy cosmic-rays (UHECRs) above 8 EeV, we explore the anisotropy induced by
+the large scale structure, using constrained simulations of the local Universe
+and taking into account the effect of magnetic fields. The value of the
+intergalactic magnetic field (IGMF) is critical as it determines the UHECR
+cosmic horizon. We calculate the UHECR sky maps for different values of the
+IGMF variance and show the effect of the UHECR horizon on the observed
+anisotropy. The footprint of the local ($\lesssim350$ Mpc) Universe on the
+UHECR background, a small angular scale enhancement in the Northern Hemisphere,
+is seen. At 11.5 EeV (the median value of the energy bin at which the dipole
+has been reported), the LSS-induced dipole amplitude is $A_1\sim10\%$, for IGMF
+in the range [0.3-3] nG for protons, helium and nitrogen, compatible with the
+rms value derived from the cosmic power spectrum. However at these energies the
+UHECRs are also influenced by the Galactic Magnetic Field (GMF) and we discuss
+its effect on the LSS-induced anisotropy.",1808.02048v2
+2018-09-02,Probing physical origin of anisotropic thermal transport in black phosphorus nanoribbons,"Black phosphorus (BP) has emerged as a promising candidate for next
+generation electronics and optoelectronics among the 2D family materials due to
+its extraordinary electrical/optical/optoelectronic properties. Interestingly,
+BP shows strong anisotropic transport behaviour because of its puckered
+honeycomb structure. Previous studies have demonstrated the thermal transport
+anisotropy of BP and theoretically attribute this to the anisotropy in both
+phonon dispersion relation and phonon relaxation time. However, the exact
+origin of such strong anisotropy lacks clarity and has yet to be proven
+experimentally. In this work, we probe the thermal transport anisotropy of BP
+nanoribbons (NRs) by an electron beam technique. We provide direct evidence
+that the origin of this anisotropy is dominated by the anisotropic phonon group
+velocity for the first time, verified by Young modulus measurements along
+different directions. It turns out that the ratio of thermal conductivity
+between zigzag (ZZ) and armchair (AC) ribbons is almost same as that of the
+corresponding Young modulus values. The results from first-principles
+calculation are consistent with this experimental observation, where
+anisotropic phonon group velocity between ZZ and AC is shown. Our results
+provide fundamental insight into the anisotropic thermal transport in low
+symmetric crystals.",1809.00302v1
+2018-10-30,Anisotropy effects on the critical magnetic field in CaC$_{6}$ superconductor,"The calcium intercalated graphite (CaC$_{6}$) is considered to be a
+representative material of the graphite intercalated superconductors, which
+exhibits sizable anisotropy of the Fermi surface (FS). Herein, the influence of
+the FS anisotropy on the critical magnetic field ($H_{C}$) in CaC$_{6}$
+superconductor is comprehensively analyzed within the Migdal-Eliashberg (M-E)
+formalism. To precisely account for the mentioned anisotropy effects, the
+analysis is conducted in the framework of the six-band approximation, hitherto
+not employed for calculations of the $H_{C}$ function in CaC$_{6}$ material.
+For convenience, the obtained results are compared with the available one- and
+three-band estimates reported by using the M-E theory. A notable signatures of
+the increased number of bands are observed for the temperature dependent
+$H_{C}$ functions. In particular, the $H_{C}$ function decreases at T=0 K as
+the number of the considered bands is higher. Moreover, it is argued that the
+six-band formalism yields the most physically relevant shape of the $H_{C}$
+function among all considered approximations. Therefore, the six-band model
+introduces not only quantitative but also qualitative changes to the results,
+in comparison to the other discussed FS approximations. This observation
+supports postulate that the six-band model constitutes minimal structure for FS
+of CaC$_{6}$, but also magnify importance of anisotropy effects for the
+critical magnetic field calculations.",1810.12878v1
+2018-11-13,Interplay between Kitaev interaction and single ion anisotropy in ferromagnetic CrI$_3$ and CrGeTe$_3$ monolayers,"Magnetic anisotropy is crucially important for the stabilization of
+two-dimensional (2D) magnetism, which is rare in nature but highly desirable in
+spintronics and for advancing fundamental knowledge. Recent works on CrI$_3$
+and CrGeTe$_3$ monolayers not only led to observations of the long-time-sought
+2D ferromagnetism, but also revealed distinct magnetic anisotropy in the two
+systems, namely Ising behavior for CrI$_3$ versus Heisenberg behavior for
+CrGeTe$_3$. Such magnetic difference strongly contrasts with structural and
+electronic similarities of these two materials, and understanding it at a
+microscopic scale should be of large benefits. Here, first-principles
+calculations are performed and analyzed to develop a simple Hamiltonian, to
+investigate magnetic anisotropy of CrI$_3$ and CrGeTe$_3$ monolayers. The
+anisotropic exchange coupling in both systems is surprisingly determined to be
+of Kitaev-type. Moreover, the interplay between this Kitaev interaction and
+single ion anisotropy (SIA) is found to naturally explain the different
+magnetic behaviors of CrI$_3$ and CrGeTe$_3$. Finally, both the Kitaev
+interaction and SIA are further found to be induced by spin-orbit coupling of
+the heavy ligands (I of CrI$_3$ or Te of CrGeTe$_3$) rather than the commonly
+believed 3d magnetic Cr ions.",1811.05413v1
+2019-01-21,Paramagnetic squeezing of a uniformly expanding quark-gluon plasma in and out of equilibrium,"The plasma of quarks and gluons created in ultrarelativistic heavy-ion
+collisions turns out to be paramagnetic. In the presence of a background
+magnetic field, this paramagnetism thus leads to a pressure anisotropy, similar
+to anisotropies appearing in a viscous fluid. In the present paper, we use this
+analogy, and develop a framework similar to anisotropic hydrodynamics, to take
+the pressure anisotropy caused, in particular, by the nonvanishing
+magnetization of a plasma of quarks and gluons into account. We consider the
+first two moments of the classical Boltzmann equation in the presence of an
+electromagnetic source in the relaxation-time approximation, and derive a set
+of coupled differential equations for the anisotropy parameter $\xi_0$ and the
+effective temperature $\lambda_0$ of an ideal fluid with nonvanishing
+magnetization. We also extend this method to a dissipative fluid with finite
+magnetization in the presence of a strong and dynamical magnetic field. We
+present a systematic method leading to the one-particle distribution function
+of this magnetized dissipative medium in a first-order derivative expansion,
+and arrive at analytical expressions for the shear and bulk viscosities in
+terms of the anisotropy parameter $\xi$ and effective temperature $\lambda$. We
+then solve the corresponding differential equations for $(\xi_0,\lambda_0)$ and
+$(\xi,\lambda)$ numerically, and determine, in this way, the proper time and
+temperature dependence of the energy density, directional pressures, speed of
+sound, and the magnetic susceptibility of a longitudinally expanding magnetized
+quark-gluon plasma in and out of equilibrium.",1901.06928v2
+2019-03-26,The orbital anisotropy profiles of nearby globular clusters from Gaia Data Release 2,"Gaia Data Release 2 provides a wealth of data to study the internal structure
+of nearby globular clusters. We use this data to investigate the internal
+kinematics of 11 nearby globular clusters, with a particular focus on their
+poorly-studied outer regions. We apply a strict set of selection criteria to
+remove contaminating sources and create pure cluster-member samples over a
+significant fraction of the radial range of each cluster. We confirm previous
+measurements of rotation (or a lack thereof) in the inner regions of several
+clusters, while extending the detection of rotation well beyond where it was
+previously measured and finding a steady decrease in rotation with radius. We
+also determine the orbital anisotropy profile and determine that clusters have
+isotropic cores, are radially anisotropic out to $\approx$ 4 half-light radii
+or $35\%$ of their limiting radii, and are then isotropic out to the limits of
+our datasets. We detect for the first time the presence of radial anisotropy in
+M 22, while confirming previous detections of radial anisotropy in 47 Tuc, M 3,
+M 13, M 15, and $\omega$ Cen's innermost regions. The implications of these
+measurements are that clusters can be separated into two categories: 1)
+clusters with observed radial anisotropy that likely formed tidally
+under-filling or are dynamically young, and 2) clusters that are primarily
+isotropic that likely formed tidally filling or are dynamically old.",1903.11070v1
+2019-04-05,Tailoring anomalous Nernst effect in stressed magnetostrictive film grown onto flexible substrate,"The anomalous Nernst effect in nanostructured magnetic materials is a key
+phenomenon to optimally control and employ the internal energy dissipated in
+electronic devices, being dependent on for instance the magnetic anisotropy of
+the active element. Thereby, here we report a theoretical and experimental
+investigation of the magnetic properties and anomalous Nernst effect in a
+flexible magnetostrictive film with induced uniaxial magnetic anisotropy and
+under external stress. Specifically, we calculate the magnetization behavior
+and the thermoelectric voltage response from a theoretical approach for a
+planar geometry and with a magnetic free energy density which takes into
+account the induced uniaxial and magnetoelastic anisotropy contributions.
+Experimentally, we verify modifications of the effective magnetic anisotropy
+and thermoelectric voltage with the stress and explore the possibility of
+tailoring the anomalous Nernst effect in a flexible magnetostrictive film by
+modifying both, the magnetic field and external stress. We find quantitative
+agreement between experiment and numerical calculations, thus elucidating the
+magnetic and thermoelectric voltage behaviors, as well as providing evidence to
+confirm the validity of the theoretical approach to describe the magnetic
+properties and anomalous Nernst effect in ferromagnetic magnetostrictive films
+having uniaxial magnetic anisotropy and submitted to external stress. Hence,
+the results place flexible magnetostrictive systems as a promising candidate
+for active elements in functionalized touch electronic devices.",1904.03125v1
+2019-04-10,The search for anisotropy in the gravitational-wave background with pulsar-timing arrays,"Pulsar-timing arrays (PTAs) are seeking gravitational waves from
+supermassive-black-hole binaries, and there are prospects to complement these
+searches with stellar-astrometry measurements. Theorists still disagree,
+however, as to whether the local gravitational-wave background will be
+statistically isotropic, as arises if it is the summed contributions from many
+SMBH binaries, or whether it exhibits the type of statistical anisotropy that
+arises if the local background is dominated by a handful (or even one) bright
+source. Here we derive, using bipolar spherical harmonics, the optimal PTA
+estimators for statistical anisotropy in the GW background and simple estimates
+of the detectability of this anisotropy. We provide results on the smallest
+detectable amplitude of a dipole anisotropy (and several other low-order
+multipole moments) and also the smallest detectable amplitude of a ""beam"" of
+gravitational waves. Results are presented as a function of the signal-to-noise
+with which the GW signal is detected and as a function of the number of pulsars
+(assuming uniform distribution on the sky and equal sensitivity per pulsar). We
+provide results first for measurements with a single time-domain window
+function and then show how the results are augmented with the inclusion of
+time-domain information. The approach here is intended to be conceptually
+straightforward and to complement the results of more detailed (but
+correspondingly less intuitive) modeling of the actual measurements.",1904.05348v3
+2019-04-12,"Unusual thermoelectric transport anisotropy in quasi-2D, rhombohedral GeTe","In this study, we calculate the $T$=300 K scattering and thermoelectric
+transport properties of rhombohedral GeTe using first-principles modeling. The
+room-temperature phase of GeTe has a layered structure, with cross-plane and
+in-plane directions oriented parallel and perpendicular to [111], respectively.
+Based on rigorous electron-phonon scattering, our transport calculations reveal
+unusual anisotropic properties; n-type GeTe has a cross-plane electrical
+conductivity that is roughly 3$\times$ larger than in-plane. p-type GeTe,
+however, displays opposite anisotropy with in-plane conducting roughly
+2$\times$ more than cross-plane, as is expected in quasi-2D materials. The
+power factor shows the same anisotropy as the electrical conductivity, since
+the Seebeck coefficient is relatively isotropic. Interestingly, cross-plane
+n-GeTe shows the largest mobility and power factor approaching 500 cm$^2$/V-s
+and 32 $\mu$W/cm-K$^2$, respectively. The thermoelectric figure-of-merit, $zT$,
+is enhanced as a result of this unusual anisotropy in n-GeTe since the lattice
+thermal conductivity is minimized along cross-plane. This decouples the
+preferred transport directions of electrons and phonons, leading to a threefold
+increase in $zT$ along cross-plane compared to in-plane. The n-type anisotropy
+results from high-velocity electron states formed by Ge p-orbitals that span
+across the interstitial region. This surprising behavior, that would allow the
+preferential conduction direction to be controlled by doping, could be observed
+in other quasi-2D materials and exploited to achieve higher-performance
+thermoelectrics.",1904.06439v2
+2019-06-02,Comparison of Shear and Compression Jammed Packings of Frictional Disks,"We compare the structural and mechanical properties of mechanically stable
+(MS) packings of frictional disks in two spatial dimensions (2D) generated with
+isotropic compression and simple shear protocols from discrete element modeling
+(DEM) simulations. We find that the average contact number and packing fraction
+at jamming onset are similar (with relative deviations $< 0.5\%$) for MS
+packings generated via compression and shear. In contrast, the average stress
+anisotropy $\langle {\hat \Sigma}_{xy} \rangle = 0$ for MS packings generated
+via isotropic compression, whereas $\langle {\hat \Sigma}_{xy} \rangle >0$ for
+MS packings generated via simple shear. To investigate the difference in the
+stress state of MS packings, we develop packing-generation protocols to first
+unjam the MS packings, remove the frictional contacts, and then rejam them.
+Using these protocols, we are able to obtain rejammed packings with nearly
+identical particle positions and stress anisotropy distributions compared to
+the original jammed packings. However, we find that when we directly compare
+the original jammed packings and rejammed ones, there are finite stress
+anisotropy deviations $\Delta {\hat \Sigma}_{xy}$. The deviations are smaller
+than the stress anisotropy fluctuations obtained by enumerating the force
+solutions within the null space of the contact networks generated via the DEM
+simulations. These results emphasize that even though the compression and shear
+jamming protocols generate packings with the same contact networks, there can
+be residual differences in the normal and tangential forces at each contact,
+and thus differences in the stress anisotropy.",1906.00438v1
+2019-07-17,Neutron Scattering Study of Magnetic Anisotropy in a Tetragonal Antiferromagnet Bi$_2$CuO$_4$,"We present a comprehensive study of magnon excitations in the tetragonal
+easy-plane anti-ferromagnet Bi$_2$CuO$_4$ using inelastic neutron scattering
+and spin wave analyses. The nature of low energy magnons, and hence the
+anisotropy in this material, has been controversial. We show unambiguously that
+the low energy magnon spectrum consists of a gapped and a gapless mode, which
+we attribute to out-of-plane and in-plane spin fluctuations, respectively. We
+modelled the observed magnon spectrum using linear spin wave analysis of a
+minimal anisotropic spin model motivated by the lattice symmetry. By studying
+the magnetic field dependence of the (1, 0, 0) Bragg peak intensity and the
+in-plane magnon intensity, we observed a spin-flop transition in the $ab$ plane
+at $\sim0.4$~T which directly indicates the existence of a small in-plane
+anisotropy that is classically forbidden. It is only by taking into account
+magnon zero-point fluctuations beyond the linear spin wave approximation, we
+could explain this in-plane anisotropy and its magnitude, the latter of which
+is deduced from critical field of the spin-flop transition. The microscopic
+origins of the observed anisotropic interactions are also discussed. We found
+that our data is inconsistent with a large Dzyaloshinskii-Moriya interaction,
+which suggests a potential departure of Bi$_2$CuO$_4$ from the conventional
+theories of magnetic anisotropy for other cuprates.",1907.07784v2
+2019-09-23,Effective macrospin model for $Co_{x}Fe_{3-x}O_{4}$ nanoparticles: decreasing the anisotropy by Co-doping?,"$Co$-doping of $Fe_{3}O_{4}$ magnetic nanoparticles is an effective way to
+tailor their magnetic properties. When considering the two extreme cases of the
+$Co_{x}Fe_{3-x}O_{4}$ series, i.e. the $x=0$ and $x=1$ values, one finds that
+the system evolves from a negative cubic-anisotropy energy constant,
+$K_{C}^{-}<0$, to a positive one, $K_{C}^{+}>0$. Thus, what happens for
+intermediate $x$-compositions? In this work we present a very simple
+phenomenological model for the anisotropy, under the \textit{macrospin}
+approximation, in which the resultant anisotropy is just directly proportional
+to the amount of $Co$. First, we perform a detailed analysis on a rather ideal
+system in which the extreme values have the same magnitude (i.e.
+$|K_{C}^{-}|=|K_{C}^{+}|$) and then we focus on the real $Co_{x}Fe_{3-x}O_{4}$
+system, for which $|K_{C}^{+}|\sim 18|K_{C}^{-}|$. Remarkably, the approach
+reproduces rather well the experimental values of the heating performance of
+$Co_{x}Fe_{3-x}O_{4}$ nanoparticles, suggesting that our simple approach may in
+fact be a good representation of the real situation. This gives rise to an
+intriguing related possibility arises: a $Co$-doping composition should exist
+for which the effective anisotropy tends to zero, estimated here as 0.05.",1909.10643v1
+2019-10-04,Spin-wave directional anisotropies in antiferromagnetic Ba$_{3}$NbFe$_{3}$Si$_{2}$O$_{14}$,"Ba$_{3}$NbFe$_{3}$Si$_{2}$O$_{14}$ (langasite) is structurally and
+magnetically single domain chiral with the magnetic helicity induced through
+competing symmetric exchange interactions. Using neutron scattering, we show
+that the spin-waves in antiferromagnetic langasite display directional
+anisotropy. On applying a time reversal symmetry breaking magnetic field along
+the $c$-axis, the spin wave energies differ when the sign is reversed for
+either the momentum transfer $\pm$ $\vec{Q}$ or applied magnetic field $\pm$
+$\mu_{0}$H. When the field is applied within the crystallographic $ab$-plane,
+the spin wave dispersion is directionally \textit{isotropic} and symmetric in
+$\pm$ $\mu_{0}$H. However, a directional anisotropy is observed in the spin
+wave intensity. We discuss this directional anisotropy in the dispersion in
+langasite in terms of a field induced precession of the dynamic unit cell
+staggered magnetization. Directional anisotropy, or often referred to as non
+reciprocal responses, can occur in antiferromagnetic phases in the absence of
+the Dzyaloshinskii-Moriya interaction or other effects resulting from
+spin-orbit coupling.",1910.01977v2
+2019-10-14,Ultrafast domain wall motion in ferrimagnets induced by magnetic anisotropy gradient,"The ultrafast magnetic dynamics in compensated ferrimagnets not only provides
+information similar to antiferromagnetic dynamics, but more importantly opens
+new opportunities for future spintronic devices [Kim et al., Nat. Mater. 16,
+1187 (2017)]. One of the most essential issues for device design is searching
+for low-power-consuming and high-efficient methods of controlling domain wall.
+In this work, we propose to use the voltage-controlled magnetic anisotropy
+gradient as an excitation source to drive the domain wall motion in
+ferrimagnets. The ultrafast wall motion under the anisotropy gradient is
+predicted theoretically based on the collective coordinate theory, which is
+confirmed by the atomistic micromagnetic simulations. The antiferromagnetic
+spin dynamics is realized at the angular momentum compensation point, and the
+wall shifting has a constant speed under small gradient and can be slightly
+accelerated under large gradient due to the broadened wall width during the
+motion. For nonzero net angular momentum, the Walker breakdown occurs at a
+critical anisotropy gradient significantly depending on the second anisotropy
+and interfacial Dzyaloshinkii-Moriya interaction, which is highly appreciated
+for further experiments including the materials selection and device geometry
+design. More importantly, this work unveils a low-power-consuming method of
+controlling the domain wall in ferrimagnets, benefiting to future spintronic
+applications.",1910.05918v1
+2019-10-14,CMB anisotropy and BBN constraints on pre-recombination decay of dark matter to visible particles,"Injection of high energy electromagnetic particles around the recombination
+epoch can modify the standard recombination history and therefore the CMB
+anisotropy power spectrum. Previous studies have put strong constraints on the
+amount of electromagnetic energy injection around the recombination era
+(redshifts $z\lesssim 4500$). However, energy injected in the form of energetic
+($>$ keV) visible standard model particles is not deposited instantaneously.
+The considerable delay between the time of energy injection and the time when
+all energy is deposited to background baryonic gas and CMB photons, together
+with the extraordinary precision with which the CMB anisotropies have been
+measured, means that CMB anisotropies are sensitive to energy that was injected
+much before the epoch of recombination. We show that the CMB anisotropy power
+spectrum is sensitive to energy injection even at $z = 10000$, giving stronger
+constraints compared to big bang nucleosynthesis and CMB spectral distortions.
+We derive, using Planck CMB data, the constraints on long-lived unstable
+particles decaying at redshifts $z\lesssim 10000$ (lifetime $\tau_X\gtrsim
+10^{11}$s) by explicitly evolving the electromagnetic cascades in the expanding
+Universe, thus extending previous constraints to lower particle lifetimes. We
+also revisit the BBN constraints and show that the delayed injection of energy
+is important for BBN constraints. We find that the constraints can be weaker by
+a factor of few to almost an order of magnitude, depending on the energy, when
+we relax the quasi-static or on-the-spot assumptions.",1910.06272v2
+2019-10-19,Mixed higher-order anisotropic flow and nonlinear response coefficients of charged particles in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 2.76 and 5.02 TeV,"Anisotropies in the initial energy density distribution of the quark-gluon
+plasma created in high energy heavy ion collisions lead to anisotropies in the
+azimuthal distributions of the final-state particles known as collective flow.
+Fourier harmonic decomposition is used to quantify these anisotropies. The
+higher-order harmonics can be induced by the same order anisotropies (linear
+response) or by the combined influence of several lower order anisotropies
+(nonlinear response) in the initial state. The mixed higher-order anisotropic
+flow and nonlinear response coefficients of charged particles are measured as
+functions of transverse momentum and centrality in PbPb collisions at
+nucleon-nucleon center-of-mass energies $\sqrt{s_\mathrm{NN}} =$ 2.76 and 5.02
+TeV with the CMS detector. The results are compared with viscous hydrodynamic
+calculations using several different initial conditions, as well as microscopic
+transport model calculations. None of the models provides a simultaneous
+description of the mixed higher-order flow harmonics and nonlinear response
+coefficients.",1910.08789v2
+2019-10-21,Overlooked transportation anisotropies in d-band correlated rare-earth perovskite nickelates,"Anisotropies in electronic transportations conventionally originate from the
+nature of low symmetries in crystal structures, and were not anticipated for
+perovskite oxides, the crystal asymmetricity of which is far below, e.g. van
+der Waals or topological crystal. Beyond conventional expectations, herein we
+demonstrate pronounced anisotropies in the inter-band coulomb repulsion
+dominated electronic transportation behaviors under low-dimensional confinement
+for the perovskite family of rare-earth nickelates (ReNiO3). From one aspect,
+imparting bi-axial interfacial strains upon various lattice planes results in
+extrinsic anisotropies in the abrupt orbital transitions of ReNiO3, and their
+metal to insulator transition behaviors that elevates the transition
+temperature beyond the existing merit. From the other aspect, the in-plane
+orbital entropy associated to the in-plane symmetry of the NiO6 octahedron
+within ReNiO3 causes intrinsic anisotropies for the gradually orbital
+transition with temperature to further improve their thermistor transportation
+properties. The present work unveils the overlooked role of the electronic
+orbital directionality within low dimensional correlated perovskites that can
+trigger anisotropic transportation behaviors, in spite of their relatively
+symmetric crystal structures. Establishing anisotropic transportations
+integrating the electron correlation and quantum confinement effects will bring
+in a new freedom for achieving further improvement in transportation properties
+of multi-functional perovskite oxides.",1910.09160v1
+2019-11-04,Validation and noise robustness assessment of microscopic anisotropy estimation with clinically feasible double diffusion encoding MRI,"Purpose: Double diffusion encoding (DDE) MRI enables the estimation of
+microscopic diffusion anisotropy, yielding valuable information on tissue
+microstructure. A recent study proposed that the acquisition of rotationally
+invariant DDE metrics, typically obtained using a spherical ""5-design"", could
+be greatly simplified by assuming Gaussian diffusion, facilitating reduced
+acquisition times that are more compatible with clinical settings. Here, we aim
+to validate the new minimal acquisition scheme against the standard DDE
+5-design, and to quantify the proposed method's noise robustness to facilitate
+future clinical use. Methods: DDE MRI experiments were performed on both ex
+vivo and in vivo rat brains at 9.4 T using the 5-design and the proposed
+minimal design and taking into account the difference in the number of
+acquisitions. The ensuing microscopic fractional anisotropy ({\mu}FA) maps were
+compared over a range of b-values up to 5000 s/mm2. Noise robustness was
+studied using analytical calculations and numerical simulations. Results: The
+minimal protocol quantified {\mu}FA at an accuracy comparable to the estimates
+obtained via the more theoretically robust DDE 5-design. {\mu}FA's sensitivity
+to noise was found to strongly depend on compartment anisotropy and tensor
+magnitude in a non-linear fashion. When {\mu}FA < 0.75 or when mean diffusivity
+is particularly low, very high signal to noise ratio (SNR) is required for
+precise quantification of {\mu}FA. Conclusion: Our work supports using DDE for
+quantifying microscopic diffusion anisotropy in clinical settings but raises
+hitherto overlooked precision issues when measuring {\mu}FA with DDE and
+typical clinical SNR.",1911.01148v1
+2019-11-13,Extended FLRW Models: dynamical cancellation of cosmological anisotropies,"We investigate a corner of the Bianchi models that has not received much
+attention: ""extended FLRW models"" (eFLRW) defined as a cosmological model with
+underlying anisotropic Bianchi geometry that nevertheless expands isotropically
+and can be mapped onto a reference FLRW model with the same expansion history.
+In order to investigate the stability and naturalness of such models in a
+dynamical systems context, we consider spatially homogeneous models that
+contain a massless scalar field $\varphi$ and a non-tilted perfect fluid
+obeying an equation of state $p=w\rho$. Remarkably, we find that matter
+anisotropies and geometrical anisotropies tend to cancel out dynamically.
+Hence, the expansion is asymptotically isotropic under rather general
+conditions. Although extended FLRW models require a special matter sector with
+anisotropies that are 'fine-tuned"" relative to geometrical anisotropies, our
+analysis shows that such solutions are dynamically preferred attractors in
+general relativity. Specifically, we prove that all locally rotationally
+symmetric Bianchi type III universes with space-like $\nabla_\mu\varphi$ are
+asymptotically shear-free, for all $w\in[-1,1]$. Moreover, all shear-free
+equilibrium sets with anisotropic spatial curvature are proved to be stable
+with respect to all homogeneous perturbations for $w\geq -1/3$.",1911.05793v2
+2020-01-29,Stationary and dynamical properties of two harmonically trapped bosons in the crossover from two dimensions to one,"We unravel the stationary properties and the interaction quench dynamics of
+two bosons, confined in a two-dimensional anisotropic harmonic trap. A
+transcendental equation is derived giving access to the energy spectrum and
+revealing the dependence of the energy gaps on the anisotropy parameter. The
+relation between the two and the one dimensional scattering lengths as well as
+the Tan contacts is established. The contact, capturing the two-body short
+range correlations, shows an increasing tendency for a larger anisotropy.
+Subsequently, the interaction quench dynamics from attractive to repulsive
+values and vice versa is investigated for various anisotropies. A closed
+analytical form of the expansion coefficients of the two-body wavefunction,
+during the time evolution is constructed. The response of the system is studied
+by means of the time-averaged fidelity, the spectra of the spatial extent of
+the cloud in each direction and the one-body density. It is found that as the
+anisotropy increases, the system becomes less perturbed independently of the
+interactions while for fixed anisotropy quenches towards the non-interacting
+regime perturb the system in the most efficient manner. Furthermore, we
+identify that in the tightly confined direction more frequencies are involved
+in the dynamics stemming from higher-lying excited states.",2001.10722v3
+2020-02-16,Using anisotropic 3D Minkowski functionals for trabecular bone characterization and biomechanical strength prediction in proximal femur specimens,"The ability of Anisotropic Minkowski Functionals (AMFs) to capture local
+anisotropy while evaluating topological properties of the underlying gray-level
+structures has been previously demonstrated. We evaluate the ability of this
+approach to characterize local structure properties of trabecular bone
+micro-architecture in ex vivo proximal femur specimens, as visualized on
+multi-detector CT, for purposes of biomechanical bone strength prediction. To
+this end, volumetric AMFs were computed locally for each voxel of volumes of
+interest (VOI) extracted from the femoral head of 146 specimens. The local
+anisotropy captured by such AMFs was quantified using a fractional anisotropy
+measure; the magnitude and direction of anisotropy at every pixel was stored in
+histograms that served as a feature vectors that characterized the VOIs. A
+linear multi-regression analysis algorithm was used to predict the failure load
+(FL) from the feature sets; the predicted FL was compared to the true FL
+determined through biomechanical testing. The prediction performance was
+measured by the root mean square error (RMSE) for each feature set. The best
+prediction performance was obtained from the fractional anisotropy histogram of
+AMF Euler Characteristic (RMSE = 1.01 +- 0.13), which was significantly better
+than MDCT-derived mean BMD (RMSE = 1.12 +- 0.16, p<0.05). We conclude that such
+anisotropic Minkowski Functionals can capture valuable information regarding
+regional trabecular bone quality and contribute to improved bone strength
+prediction, which is important for improving the clinical assessment of
+osteoporotic fracture risk.",2002.07156v1
+2020-02-24,A Generalized framework of weak value amplification in path interference of polarized light for the enhancement of all possible polarization anisotropy effects,"Using the profound interferometric philosophy of weak value amplification, we
+propose a simple, general and a robust polarization method for the
+amplification and quantification of small magnitudes of all possible
+polarization anisotropy effects in a single experimental embodiment. The
+approach is experimentally realized by introducing a weak coupling between the
+polarization degree of freedom of light and the path degree of freedom in a
+Mach-Zehnder interferometer in the presence of a weak anisotropy effect. Real
+and imaginary weak value amplifications of different polarization anisotropy
+effects are manifested as characteristic changes in relevant Stokes vector
+elements at the exit port of the interferometer, which follow orthogonal
+trajectories in the Poincare sphere. The proof of concept experiment
+demonstrates that using this scheme, one can faithfully extract and quantify
+anisotropy parameter that is smaller than the typical sensitivity of
+measurement of a given Stokes parameter of a traditional polarimeter by a large
+weak value amplification factor. This opens up possibility of a sample
+measuring weak value polarimeter for studying rich variety of fundamental
+optical effects and for materials characterization and precision metrology.",2002.10093v2
+2020-03-28,Acoustic Wave Induced FMR Assisted Spin-Torque Switching of Perpendicular MTJs with Anisotropy Variation,"We have investigated Surface Acoustic Wave (SAW) induced ferromagnetic
+resonance (FMR) assisted Spin Transfer Torque (STT) switching of perpendicular
+MTJ (p-MTJ) with inhomogeneities using micromagnetic simulations that include
+the effect of thermal noise. With suitable frequency excitation, the SAW can
+induce ferromagnetic resonance in magnetostrictive materials, and the
+magnetization can precesses in a cone with high deflection from the
+perpendicular direction. With incorporation of inhomogeneity via lateral
+anisotropy variation as well as room temperature thermal noise, the
+magnetization precession in different gains can be significantly incoherent.
+Interestingly, the precession in different grains are found to be in phase,
+even though the precession amplitude (angle of deflection from the
+perpendicular direction) vary across grains of different anisotropy.
+Nevertheless, the high mean deflection angle can complement the STT switching
+by reducing the STT current significantly; even though the applied stress
+induced change in anisotropy is much lower than the total anisotropy barrier.
+This work indicates that SAW assisted switching can improve energy efficiency
+while being scalable to very small dimensions, which is technologically
+important for STT-RAM and elucidates the physical mechanism for the potential
+robustness of this paradigm in realistic scenarios with thermal noise and
+material inhomogeneity",2003.12903v1
+2020-04-11,Investigation of Magnetic Anisotropy and Heat Dissipation in Thin Films of Compensated Antiferromagnet CuMnAs by Pump-probe Experiment,"We recently reported on a method to determine the easy axis position in a 10
+nm thick film of the fully compensated antiferromagnet CuMnAs. The film had a
+uniaxial magnetic anisotropy and the technique utilized a magneto-optical pump
+and probe experiment [Nature Photonics 11, 91 (2017)]. In this contribution we
+discuss the applicability of this method for the investigation of a broader set
+of epitaxial CuMnAs films having different thicknesses. This work reveals that
+the equilibrium magnetic anisotropy can be studied only in samples where this
+anisotropy is rather strong. However, in the majority of CuMnAs films, the
+impact of a strong pump pulse induces nano-fragmentation of the magnetic
+domains and, therefore, the magnetic anisotropy measured by the pump-probe
+technique differs substantially from that in the equilibrium conditions. We
+also demonstrate that optical pump-probe experiment can be used very
+efficiently to study the local heating and heat dissipation in CuMnAs epitaxial
+layers. In particular, we determined the electron-phonon relaxation time in
+CuMnAs. We also observed that for a local film heating by a focused laser the
+thinner films are heated more, but the heat is dissipated considerably faster
+than in the case of thicker films. This illustrates that the optical pump-probe
+experiment is a valuable characterization tool for the heat management
+optimization in the CuMnAs memory devices and can be applied in a similar way
+to those used during heat-assisted magnetic recording (HAMR) technology
+development for the latest generation of hard drive disks.",2004.05360v2
+2020-04-23,Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer,"Engineering magnetic anisotropy in two-dimensional systems has enormous
+scientific and technological implications. The uniaxial anisotropy universally
+exhibited by two-dimensional magnets has only two stable spin directions,
+demanding 180 degrees spin switching between states. We demonstrate a novel
+eightfold anisotropy in magnetic SrRuO3 monolayers by inducing a spin
+reorientation in (SrRuO3)1/(SrTiO3)N superlattices, in which the magnetic easy
+axis of Ru spins is transformed from uniaxial <001> direction (N = 1 and 2) to
+eightfold <111> directions (N = 3, 4 and 5). This eightfold anisotropy enables
+71 and 109 degrees spin switching in SrRuO3 monolayers, analogous to 71 and 109
+degrees polarization switching in ferroelectric BiFeO3. First-principle
+calculations reveal that increasing the SrTiO3 layer thickness induces an
+emergent correlation-driven orbital ordering, tuning spin-orbit interactions
+and reorienting the SrRuO3 monolayer easy axis. Our work demonstrates that
+correlation effects can be exploited to substantially change spin-orbit
+interactions, stabilizing unprecedented properties in two-dimensional magnets
+and opening rich opportunities for low-power, multi-state device applications.",2004.10939v1
+2020-05-04,Anisotropy of electronic correlations: On the applicability of local theories to layered materials,"Besides the chemical constituents, it is the lattice geometry that controls
+the most important material properties. In many interesting compounds, the
+arrangement of elements leads to pronounced anisotropies, which reflect into a
+varying degree of quasi two-dimensionality of their low-energy excitations.
+Here, we start by classifying important families of correlated materials
+according to a simple measure for the tetragonal anisotropy of their ab initio
+electronic (band) structure. Second, we investigate the impact of a
+progressively large anisotropy in driving the non-locality of many-body
+effects. To this end, we tune the Hubbard model from isotropic cubic in three
+dimensions to the two-dimensional limit and analyze it using the dynamical
+vertex approximation. For sufficiently isotropic hoppings, we find the
+self-energy to be well separable into a static non-local and a dynamical local
+contribution. While the latter could potentially be obtained from dynamical
+mean-field approaches, we find the former to be non-negligible in all cases.
+Further, by increasing the model-anisotropy, we quantify the degree of quasi
+two-dimensionality which causes this ""space-time separation"" to break down. Our
+systematic analysis improves the general understanding of electronic
+correlations in anisotropic materials, heterostructures and ultra-thin films,
+and provides useful guidance for future realistic studies.",2005.01369v1
+2020-05-11,Skyrmion confinement and dynamics in tracks patterned with magnetic anisotropy: theory and simulations,"Skyrmion is a topologically protected spin texture excited in magnetic thin
+films. The radii of skyrmions are typically 10-100 nm. Because of the size, the
+skyrmion is expected to be a candidate for memory and novel-device usages. To
+realize the futuristic devices that will be using the skyrmion circuit, the
+tracks which guide the motion of skyrmions are needed. The tracks patterned
+with differences in the magnetic-anisotropy energy are well-paved without a
+potential pocket, whereas the tracks carved out of magnetic films have the
+potential pockets at corners due to the demagnetizing field. Therefore, the
+tracks patterned with the magnetic anisotropy plays a key role in making the
+skyrmion circuits. The experiment along this idea has been conducted for the
+hub and bent tracks. However, we have little known the motion of skyrmions in
+these tracks. This work aims to identify the forces acting between skyrmions
+and walls of the tracks. The static force on a skyrmion can be expressed as
+minus the gradient of the potential energy caused by the magnetic-anisotropy
+undulation. The potential can be estimated numerically, modeling the shape of
+skyrmions with their radii and domain wall widths. We find that the forces
+depend not only on the distance from the wall but also on the shape of
+skyrmions. We have also performed micromagnetic simulations where the Magnus
+force and the acceleration by the magnetic-anisotropy gradient are taken into
+account as well as the force by the walls. The simulation results show good
+agreement with those calculated from the modeled skyrmions.",2005.04860v1
+2020-06-01,Giant optical anisotropy in transition metal dichalcogenides for next-generation photonics,"Large optical anisotropy observed in a broad spectral range is of paramount
+importance for efficient light manipulation in countless devices. Although a
+giant anisotropy was recently observed in the mid-infrared wavelength range,
+for visible and near-infrared spectral intervals, the problem remains acute
+with the highest reported birefringence values of 0.8 in BaTiS3 and h-BN
+crystals. This inspired an intensive search for giant optical anisotropy among
+natural and artificial materials. Here, we demonstrate that layered transition
+metal dichalcogenides (TMDCs) provide an answer to this quest owing to their
+fundamental differences between intralayer strong covalent bonding and weak
+interlayer van der Walls interaction. To do this, we carried out a correlative
+far- and near-field characterization validated by first-principle calculations
+that reveals an unprecedented birefringence of 1.5 in the infrared and 3 in the
+visible light for MoS2. Our findings demonstrate that this outstanding
+anisotropy allows for tackling the diffraction limit enabling an avenue for
+on-chip next-generation photonics.",2006.00884v3
+2020-06-04,Observational quantification of three-dimensional anisotropies and scalings of space plasma turbulence at kinetic scales,"A statistical survey of spectral anisotropy of space plasma turbulence is
+performed using five years measurements from MMS in the magnetosheath. By
+measuring the five-point second-order structure functions of the magnetic
+field, we have for the first time quantified the three-dimensional anisotropies
+and scalings at sub-ion-scales ($<$ 100 km). In the local reference frame
+$(\hat L_{\perp}, \hat l_{\perp}, \hat l_{\parallel})$ defined with respect to
+local mean magnetic field $\boldsymbol {B}_0$ (Chen et al. 2012), the
+""statistical eddies"" are found to be mostly elongated along $\boldsymbol {B}_0$
+and shortened in the direction perpendicular to both $\boldsymbol {B}_0$ and
+local field fluctuations. From several $d_i$ (ion inertial length) toward
+$\sim$ 0.05 $d_i$, the ratio between eddies' parallel and perpendicular lengths
+features a trend of rise then fall, whereas the anisotropy in the perpendicular
+plane appears scale-invariant. Specifically, the anisotropy relations for the
+total magnetic field at 0.1-1.0 $d_i$ are obtained as $l_{\parallel} \simeq
+2.44 \cdot l_{\perp}^{0.71}$, and $L_{\perp} \simeq 1.58 \cdot
+l_{\perp}^{1.08}$, respectively. Our results provide new observational evidence
+to compare with phenomenological models and numerical simulations, which may
+help to better understand the nature of kinetic scale turbulence.",2006.02722v1
+2020-07-14,QCD Axions and CMB Anisotropy,"In this paper, we consider a possibility that the temperature anisotropy of
+cosmic microwave background (CMB) is dominantly generated by the primordial
+fluctuations of QCD-axion like particles under a circumstance that inflaton's
+perturbation is too small to explain the CMB anisotropy. Since the axion
+potential is generated by acquiring its energy from radiation, the primordial
+fluctuations of the axion field generated in the inflation era are correlated
+with the CMB anisotropies. Consequently, the observations stringently constrain
+a model of the axion and the early universe scenario. The following conditions
+must be satisfied: (i) sufficient amplitudes of the CMB anisotropy (ii)
+consistency with the axion isocurvature constraint and (iii) the
+non-Gaussianity constraint. To satisfy these conditions, a large energy
+fraction $\Omega_A^{}$ of the axion is necessary at the QCD scale when the
+axion-potential is generated, but simultaneously, it must become tiny at the
+present era due to the isocurvature constraint. Thus an additional scenario of
+the early universe, such as low scale thermal inflation, is inevitable to
+dilute the axions after the QCD scale. We investigate such a model and obtain
+its allowed parameter region.",2007.06802v2
+2020-07-16,Stability of in-plane and out-of-plane chiral skyrmions in epitaxial MnSi(111)/Si(111) thin films: surface twists versus easy-plane anisotropy,"The revisited theoretical phase diagrams for thin films of cubic helimagnets
+with the easy-plane anisotropy are shown to have different topology as
+previously reported [Phys. Rev. B 85, 094429 (2012)]. For both in-plane and
+out-of-plane directions of an applied magnetic field, the phase diagrams
+exhibit extensive areas of stable skyrmions, which overlap for a wide range of
+anisotropy parameters. Although the existence of the out-of-plane skyrmions was
+contradicted within the previous theoretical models, we prove that additional
+surface twists lead to their stability, while the moderate easy-plane
+anisotropy increases the stability range of in-plane skyrmions. Moreover, the
+interplay between the anisotropy and the surface twists gives rise to a stable
+spiral state canted with respect to the surfaces. Being absent in bulk
+helimagnets, this oblique spiral occupies vast areas at the phase diagrams in
+thin-film nanosystems and serves as a connecting-link between cones and
+helicoids. Our theory gives clear directions for renewed experimental studies
+of in-plane and out-of-plane skyrmions in epitaxial MnSi(111)/Si(111) thin
+films.",2007.08065v1
+2020-08-31,Single-ion anisotropy effects on the critical behaviors of quantum entanglement and correlation in the spin-1 Heisenberg chain,"Quantum entanglement and correlations in the spin-1 Heisenberg chain with
+single-ion anisotropy are investigated using the quantum renormalization group
+method. Negativity and quantum discord (QD) are calculated with various
+anisotropy parameters $\bigtriangleup$ and single-ion anisotropy parameters
+$D$. We focus on the relations between two abovementioned physical quantities
+and on transitions between the N\'eel, Haldane, and Large-D phases. It is found
+that both negativity and QD exhibit step-like patterns in different phases as
+the size of the system increases. Interestingly, the single-ion anisotropy
+parameter $D$, which can be modulated using nuclear electric resonance (2020
+\textit{Nature} \textbf{579} 205), plays an important role in tuning the
+quantum phase transition (QPT) of the system. Both the first partial derivative
+of the negativity and quantum discord with respect to $D$ or $\bigtriangleup$
+exhibit nonanalytic behavior at the phase transition points, which corresponds
+directly to the divergence of the correlation length. The quantum correlation
+critical exponents derived from negativity and QD are equal, and are the
+reciprocal of the correlation length exponent at each critical point. This work
+extends the application of quantum entanglement and correlations as tools for
+depicting QPTs in spin-1 systems.",2008.13641v3
+2020-09-09,Minimum variance estimation of statistical anisotropy via galaxy survey,"We consider the benefits of measuring cosmic statistical anisotropy from
+redshift-space correlators of the galaxy number density fluctuation and the
+peculiar velocity field without adopting the plane-parallel (PP) approximation.
+Since the correlators are decomposed using the general tripolar spherical
+harmonic (TripoSH) basis, we can deal with wide-angle contributions untreatable
+by the PP approximation, and at the same time, target anisotropic signatures
+can be cleanly extracted. We, for the first time, compute the covariance of the
+TripoSH decomposition coefficient and the Fisher matrix to forecast the
+detectability of statistical anisotropy. The resultant expression of the
+covariance is free from nontrivial mixings between each multipole moment caused
+by the PP approximation and hence the detectability is fully optimized.
+Compared with the analysis under the PP approximation, the superiority in
+detectability is always confirmed, and it is highlighted, especially in the
+cases that the shot noise level is large and that target statistical anisotropy
+has a blue-tilted shape in Fourier space. The application of the TripoSH-based
+analysis to forthcoming all-sky survey data could result in constraints on
+anisotropy comparable to or tighter than the current cosmic microwave
+background ones.",2009.04355v2
+2020-09-14,"Effect of controlled point-like disorder induced by 2.5 MeV electron irradiation on nematic resistivity anisotropy of hole-doped (Ba,K)Fe$_2$As$_2$","In-plane anisotropy of electrical resistivity was studied in samples of the
+hole-doped Ba$_{1-x}$K$_x$Fe$_2$As$_2$ in the composition range $0.21 \leq x
+\leq 0.26$ where anisotropy changes sign. Low-temperature ($\sim$20~K)
+irradiation with relativistic 2.5 MeV electrons was used to control the level
+of disorder and residual resistivity of the samples. Modification of the
+stress-detwinning technique enabled measurements of the same samples before and
+after irradiation, leading to conclusion of anisotropic character of
+predominantly inelastic scattering processes. Our main finding is that the
+resistivity anisotropy is of the same sign irrespective of residual
+resistivity, and remains the same in the orthorhombic $C_2$ phase above the
+re-entrant tetragonal transition. Unusual $T$-linear dependence of the
+anisotropy $\Delta \rho \equiv \rho_a(T)-\rho_b(T)$ is found in pristine
+samples with $x=$0.213 and $x=$0.219, without similar signatures in either
+$\rho_a(T)$ or $\rho_b(T)$. We show that this feature can be reproduced by a
+phenomenological model of R.~M.~Fernandes {\it et al.} Phys. Rev. Lett. {\bf
+107},217002 (2011). We speculate that onset of fluctuations of nematic order on
+approaching the instability towards the re-entrant tetragonal phase contributes
+to this unusual dependence.",2009.06753v1
+2020-10-02,Singular magnetic anisotropy in the nematic phase of FeSe,"FeSe is arguably the simplest, yet the most enigmatic, iron-based
+superconductor. Its nematic but non-magnetic ground state is unprecedented in
+this class of materials and stands out as a current puzzle. Here, our NMR
+measurements in the nematic state of mechanically detwinned FeSe reveal that
+both the Knight shift and the spin-lattice relaxation rate 1/T_1 possess an
+in-plane anisotropy opposite to that of the iron pnictides LaFeAsO and
+BaFe2As2. Using a microscopic electron model that includes spin-orbit coupling,
+our calculations show that an opposite quasiparticle weight ratio between the
+d_xz and d_yz orbitals leads to an opposite anisotropy of the orbital magnetic
+susceptibility, which explains our Knight shift results. We attribute this
+property to a different nature of nematic order in the two compounds,
+predominantly bond-type in FeSe and onsite ferro-orbital in pnictides. The T_1
+anisotropy is found to be inconsistent with existing neutron scattering data in
+FeSe, showing that the spin fluctuation spectrum reveals surprises at low
+energy, possibly from fluctuations that do not break C_4 symmetry. Therefore,
+our results reveal that important information is hidden in these anisotropies
+and they place stringent constraints on the low-energy spin correlations as
+well as on the nature of nematicity in FeSe.",2010.01020v1
+2020-10-02,Electron Temperature Anisotropy and Electron Beam Constraints From Electron Kinetic Instabilities in the Solar Wind,"Electron temperature anisotropies and electron beams are nonthermal features
+of the observed nonequilibrium electron velocity distributions in the solar
+wind. In collision-poor plasmas these nonequilibrium distributions are expected
+to be regulated by kinetic instabilities through wave-particle interactions.
+This study considers electron instabilities driven by the interplay of core
+electron temperature anisotropies and the electron beam, and firstly gives a
+comprehensive analysis of instabilities in arbitrary directions to the
+background magnetic field. It clarifies the dominant parameter regime (e.g.,
+parallel core electron plasma beta $\beta_{\mathrm{ec\parallel}}$, core
+electron temperature anisotropy $A_{\mathrm{ec}}\equiv
+T_{\mathrm{ec\perp}}/T_{\mathrm{ec\parallel}}$, and electron beam velocity
+$V_{\mathrm{eb}}$) for each kind of electron instability (e.g., the electron
+beam-driven electron acoustic/magnetoacoustic instability, the electron
+beam-driven whistler instability, the electromagnetic electron cyclotron
+instability, the electron mirror instability, the electron firehose
+instability, and the ordinary-mode instability). It finds that the electron
+beam can destabilize electron acoustic/magnetoacoustic waves in the
+low-$\beta_{\mathrm{ec\parallel}}$ regime, and whistler waves in the medium-
+and large-$\beta_{\mathrm{ec\parallel}}$ regime. It also finds that a new
+oblique fast-magnetosonic/whistler instability is driven by the electron beam
+with $V_{\mathrm{eb}}\gtrsim7V_{\mathrm{A}}$ in a regime where
+$\beta_{\mathrm{ec\parallel}}\sim0.1-2$ and $A_{\mathrm{ec}}<1$. Moreover, this
+study presents electromagnetic responses of each kind of electron instability.
+These results provide a comprehensive overview for electron instability
+constraints on core electron temperature anisotropies and electron beams in the
+solar wind.",2010.01066v1
+2020-10-10,Highly anisotropic two-dimensional metal in monolayer MoOCl$_2$,"Anisotropy is a general feature in materials. Strong anisotropy could lead to
+interesting physical properties and useful applications. Here, based on
+first-principles calculations and theoretical analysis, we predict a stable
+two-dimensional (2D) material---the monolayer MoOCl$_2$, and show that it
+possesses intriguing properties related to its high anisotropy. Monolayer
+MoOCl$_2$ can be readily exfoliated from the van der Waals layered bulk, which
+has already been synthesized. We show that a high in-plane anisotropy manifests
+in the structural, phononic, mechanical, electronic, and optical properties of
+monolayer MoOCl$_2$. The material is a metal with highly anisotropic Fermi
+surfaces, giving rise to open orbits at the Fermi level, which can be probed in
+magneto-transport. Remarkably, the combination of high anisotropy and metallic
+character makes monolayer MoOCl$_2$ an almost ideal hyperbolic material. It has
+two very wide hyperbolic frequency windows from 0.41 eV (99 THz) to 2.90 eV
+(701 THz), and from 3.63 eV (878 THz) to 5.54 eV (1340 THz). The former window
+has a large overlap with the visible spectrum, and the dissipation for most
+part of this window is very small. The window can be further tuned by the
+applied strain, such that at a chosen frequency, a transition between elliptic
+and hyperbolic character can be induced by strain. Our work discovers a highly
+anisotropic 2D metal with extraordinary properties, which holds great potential
+for electronic and optical applications.",2010.04923v1
+2020-10-30,Effect of Single-ion Anisotropy on Magnetocaloric Properties of Frustrated Spin-$s$ Ising Nanoclusters,"Effects of a single-ion anisotropy on magnetocaloric properties of selected
+spin-$s\geq 1$ antiferromagnetic Ising clusters with frustration-inducing
+triangular geometry are studied by exact enumeration. It is found that
+inclusion of the single-ion anisotropy parameter $D$ can result in a much more
+complex ground-state behavior, which is also reflected in a magnetocaloric
+effect (MCE) at finite temperatures. For negative $D$ (easy-plane anisotropy)
+with increasing $s$ the ground-state magnetization as a function of the
+external field gradually shows increasing number of plateaus of various
+heights. Except for the cases of integer $s$ with $D < D_0 \leq 0$, the first
+magnetization plateau is of non-zero height. This property facilitates an
+enhanced MCE in the adiabatic demagnetization process in the form of an abrupt
+decrease in temperature as the magnetic field vanishes to zero. The cooling
+rate can be considerably enhanced in the systems with larger $s$ and $D>0$
+(easy-axis anisotropy), albeit its dependence on these parameters is strongly
+dependent on the cluster geometry. From the studied systems more favorable
+conditions for observing a giant MCE were found in the 2CS cluster, consisting
+of two corner-sharing tetrahedra, the experimental realization of which could
+be technologically used for efficient refrigeration to ultra-low temperatures.",2010.16287v1
+2021-02-18,The relationship between transport anisotropy and nematicity in FeSe,"The mechanism behind the nematicity of FeSe is not known. Through
+elastoresitivity measurements it has been shown to be an electronic
+instability. However, so far measurements have extended only to small strains,
+where the response is linear. Here, we apply large elastic strains to FeSe, and
+perform two types of measurements. (1) Using applied strain to control
+twinning, the nematic resistive anisotropy at temperatures below the nematic
+transition temperature Ts is determined. (2) Resistive anisotropy is measured
+as nematicity is induced through applied strain at fixed temperature above Ts.
+In both cases, as nematicity strengthens the resistive anisotropy peaks about
+about 7%, then decreases. Below ~40 K, the nematic resistive anisotropy changes
+sign. We discuss possible implications of this behaviour for theories of
+nematicity. We report in addition: (1) Under experimentally accessible
+conditions with bulk crystals, stress, rather than strain, is the conjugate
+field to the nematicity of FeSe. (2) At low temperatures the twin boundary
+resistance is ~10% of the sample resistance, and must be properly subtracted to
+extract intrinsic resistivities. (3) Biaxial inplane compression increases both
+in-plane resistivity and the superconducting critical temperature Tc,
+consistent with a strong role of the yz orbital in the electronic correlations.",2102.09212v1
+2021-03-22,Intensity and anisotropies of the stochastic Gravitational Wave background from merging compact binaries in galaxies,"We investigate the isotropic and anisotropic components of the Stochastic
+Gravitational Wave Background (SGWB) originated from unresolved merging compact
+binaries in galaxies. We base our analysis on an empirical approach to galactic
+astrophysics that allows to follow the evolution of individual systems. We then
+characterize the energy density of the SGWB as a tracer of the total matter
+density, in order to compute the angular power spectrum of anisotropies with
+the Cosmic Linear Anisotropy Solving System (CLASS) public code in full
+generality. We obtain predictions for the isotropic energy density and for the
+angular power spectrum of the SGWB anisotropies, and study the prospect for
+their observations with advanced Laser Interferometer Gravitational-Wave and
+Virgo Observatories and with the Einstein Telescope. We identify the
+contributions coming from different type of sources (binary black holes, binary
+neutron stars and black hole-neutron star) and from different redshifts. We
+examine in detail the spectral shape of the energy density for all types of
+sources, comparing the results for the two detectors. We find that the power
+spectrum of the SGWB anisotropies behaves like a power law on large angular
+scales and drops at small scales: we explain this behaviour in terms of the
+redshift distribution of sources that contribute most to the signal, and of the
+sensitivities of the two detectors. Finally, we simulate a high resolution full
+sky map of the SGWB starting from the power spectra obtained with CLASS and
+including Poisson statistics and clustering properties.",2103.12037v2
+2021-04-01,"Scale-dependent anisotropy, energy transfer and intermittency in bubble-laden turbulent flows","Data from Direct Numerical Simulations of disperse bubbly flows in a vertical
+channel are used to study the effect of the bubbles on the carrier-phase
+turbulence. A new method is developed, based on the barycentric map approach,
+that allows to quantify the anisotropy and componentiality of the flow at any
+scale. Using this the bubbles are found to significantly enhance flow
+anisotropy at all scales compared with the unladen case, and for some bubble
+cases, very strong anisotropy persists down to the smallest flow scales. The
+strongest anisotropy observed was for the cases involving small bubbles.
+Concerning the inter-scale energy transfer, our results indicate that for the
+bubble-laden cases, the energy transfer is from large to small scales, just as
+for the unladen case. However, there is evidence of an upscale transfer when
+considering the transfer of energy associated with particular components of the
+velocity field. Although the direction of the energy transfer is the same with
+and without the bubbles, the transfer is much stronger for the bubble-laden
+cases, suggesting that the bubbles play a strong role in enhancing the activity
+of the nonlinear term in the flow. The normalized forms of the fourth and
+sixth-order structure functions are also considered, and reveal that the
+introduction of bubbles into the flow strongly enhances intermittency in the
+dissipation range, but suppresses it at larger scales. This strong enhancement
+of the dissipation scale intermittency has significant implications for
+understanding how the bubbles might modify the mixing properties of turbulent
+flows.",2104.00449v1
+2021-05-17,Computing Curie temperature of two-dimensional ferromagnets in the presence of exchange anisotropy,"We compare three first-principles methods of calculating the Curie
+temperature in two-dimensional (2D) ferromagnetic materials (FM), modeled using
+the Heisenberg model, and propose a simple formula for estimating the Curie
+temperature with high accuracy that works for all common 2D lattice types.
+First, we study the effect of exchange anisotropy on the Curie temperature
+calculated using the Monte-Carlo (MC), the Green's function method, and the
+renormalized spin-wave (RNSW). We find that the Green's function overestimates
+the Curie temperature in high-anisotropy regimes compared to MC, whereas RNSW
+underestimates the Curie temperature compared to the MC and the Green's
+function. Next, we propose a closed-form formula for calculating the Curie
+temperature of 2D FMs, which provides an estimate of the Curie temperature
+greatly improving over the mean-field expression for magnetic material
+screening. We apply the closed-form formula to predict the Curie temperature 2D
+magnets screened from the C2DB database and discover several high Curie
+temperature FMs with Fe2F2 and MoI2 emerging as the most promising 2D
+ferromagnets. Finally, comparing to experimental results for CrI3, CrCl3, and
+CrBr3, we conclude that for small effective anisotropies, the Green's
+function-based equations are preferable, while, for larger anisotropies
+MC-based results are more predictive.",2105.07958v3
+2021-05-24,Tuning of magnetic structures topology via single-ion anisotropy and magnetic field in frustrated 2D semiconductors,"The effects of competing magnetic interactions in stabilizing different spin
+configurations are drawing a renewed attention in order to both unveil emerging
+topological spin textures and to highlight microscopic mechanisms leading to
+their stabilization. The possible key role of the two-site exchange anisotropy
+in selecting specific helicity and vorticity of skyrmionic lattices has only
+recently been proposed. In this work we explore the phase diagram of a
+frustrated localized magnet on a two-dimensional centrosymmetric triangular
+lattice, focusing on the interplay between the two-ion anisotropy (TIA) and the
+single-ion anisotropy (SIA). The effects of an external magnetic field applied
+perpendicularly to the magnetic layer are also investigated. By means of Monte
+Carlo simulations, we find a profusion of different spin configurations, going
+from trivial to high-order Q skyrmionic and meronic lattices. In closer detail,
+we find that a dominant role is played by the two-ion over the single-ion
+anisotropy in determining the planar spin texture, whereas the strength and
+sign of SIA, together with the magnitude of the magnetic field, tune the
+perpendicular spin components, mostly affecting the polarity (and, in turn, the
+topology) of the spin-texture. Our analysis confirms the crucial role of
+anisotropic symmetric exchange in systems with dominant short-range
+interactions, at the same time predicting a rich variety of complex magnetic
+textures that may arise from a fine tuning of competing anisotropic mechanisms.",2105.11411v1
+2021-07-01,Controllable inter-skyrmion attractions and resulting skyrmion-lattice structures in two-dimensional chiral magnets with in-plane anisotropy,"We study inter-skyrmion interactions and stable spin configurations in a 2D
+chiral magnet with in-plane anisotropies of a tilted magnetic field and the
+magneto-crystalline anisotropy on a (011) thin film. We find that in both cases
+a small deformation of a skyrmion shape makes the inter-skyrmion interaction
+anisotropic, and that the skyrmions are weakly bounded along a certain
+direction due to an emergent attractive interaction. Furthermore, when the
+magneto-crystalline anisotropy is comparable to the Zeeman energy, skyrmions
+embedded in a uniform magnetization are tightly bound by creating a magnetic
+domain between them. The formation of the magnetic domain, and thus the
+strength of the inter-skyrmion interaction, can be controlled by the direction
+of an external magnetic field. The anisotropic interaction also affects the
+skyrmion alignment in the skyrmion crystal (SkX) phase. By employing the Monte
+Carlo simulation and the micromagnetic simulation, we obtain an elongated
+triangular lattice structure in the SkX phase. In particular, in the presence
+of a strong magneto-crystalline anisotropy, magnetic domains appear in the
+background of the lattice structure, and bimerons aligned on the domain walls
+form an elongated triangular lattice. We also find a parameter region that the
+SkX phase is stabilized due to the inter-skyrmion attraction.",2107.00201v1
+2021-08-05,Metamagnetic Transitions in Few-Layer CrOCl Controlled by Magnetic Anisotropy Flipping,"The pivotal role of magnetic anisotropy in stabilising two-dimensional (2D)
+magnetism has been widely accepted, however, direct correlation between
+magnetic anisotropy and long-range magnetic ordering in the 2D limit is yet to
+be explored. Here, using angle- and temperature-dependent tunnelling
+magnetoresistance, we report unprecedented metamagnetic phase transitions in
+atomically-thin CrOCl, triggered by magnetic easy-axis flipping instead of the
+conventional spin flop mechanism. Few-layer CrOCl tunnelling devices of various
+thicknesses consistently show an in-plane antiferromagnetic (AFM) ground state
+with the easy axis aligned along the Cr-O-Cr direction (b-axis). Strikingly,
+with the presence of a magnetic field perpendicular to the easy-axis (H||c),
+magnetization of CrOCl does not follow the prevalent spin rotation and
+saturation pattern, but rather exhibits an easy-axis flipping from the in-plane
+to out-of-plane directions. Such magnetic anisotropy controlled metamagnetic
+phase transitions are manifested by a drastic upturn in tun- nelling current,
+which shows anomalous shifts towards higher H when temperature increases. By 2D
+mapping of tunnelling currents as a function of both temperature and H, we
+determine a unique ferrimagnetic state with a superstructure periodicity of
+five unit cells after the field-induced metam- agnetic transitions. The
+feasibility to control 2D magnetism by manipulating magnetic anisotropy may
+open enormous opportunities in spin-based device applications.",2108.02825v1
+2021-09-05,Lateral modulation of magnetic anisotropy in tricolor 3d-5d oxide superlattices,"Manipulating magnetic anisotropy (MA) purposefully in transition metal oxides
+(TMOs) enables the development of oxide-based spintronic devices with practical
+applications. Here, we report a pathway to reversibly switch the lateral
+magnetic easy-axis via interfacial oxygen octahedral coupling (OOC) effects in
+3d-5d tricolor superlattices, i.e. [SrIrO3,mRTiO3,SrIrO3,2La0.67Sr0.33MnO3]10
+(RTiO3: SrTiO3 and CaTiO3). In the heterostructures, the anisotropy energy
+(MAE) is enhanced over one magnitude to ~106 erg/cm3 compared to
+La0.67Sr0.33MnO3 films. Moreover, the magnetic easy-axis is reversibly
+reoriented between (100)- and (110)-directions by changing the RTiO3. Using
+first-principles density functional theory calculations, we find that the
+SrIrO3 owns a large single-ion anisotropy due to its strong spin-orbit
+interaction. This anisotropy can be reversibly controlled by the OOC, then
+reorient the easy-axis of the superlattices. Additionally, it enlarges the MAE
+of the films via the cooperation with a robust orbital hybridization between
+the Ir and Mn atoms. Our results indicate that the tricolor superlattices
+consisting of 3d and 5d oxides provide a powerful platform to study the MA and
+develop oxide-based spintronic devices.",2109.02062v1
+2021-10-01,Measurement of the Anisotropy Power Spectrum of the Radio Synchrotron Background,"We present the first targeted measurement of the power spectrum of
+anisotropies of the radio synchrotron background, at 140 MHz where it is the
+overwhelmingly dominant photon background. This measurement is important for
+understanding the background level of radio sky brightness, which is dominated
+by steep-spectrum synchrotron radiation at frequencies below 0.5 GHz and has
+been measured to be significantly higher than that which can be produced by
+known classes of extragalactic sources and most models of Galactic halo
+emission. We determine the anisotropy power spectrum on scales ranging from 2
+degrees to 0.2 arcminutes with LOFAR observations of two 18 square degree
+fields -- one centered on the Northern hemisphere coldest patch of radio sky
+where the Galactic contribution is smallest and one offset from that location
+by 15 degrees. We find that the anisotropy power is higher than that
+attributable to the distribution of point sources above 100 micro-Jy in flux.
+This level of radio anisotropy power indicates that if it results from point
+sources, those sources are likely at low fluxes and incredibly numerous, and
+likely clustered in a specific manner.",2110.00499v3
+2021-11-11,"No longer ballistic, not yet diffusive--the formation of cosmic ray small-scale anisotropies","The arrival directions of TeV-PeV cosmic rays are remarkably uniform due to
+the isotropization of their directions by scattering on turbulent magnetic
+fields. Small anisotropies can exist in standard diffusion models, however,
+only on the largest angular scales. Yet, high-statistics observatories like
+IceCube and HAWC have found significant deviations from isotropy down to small
+angular scales. Here, we explain the formation of small-scale anisotropies by
+considering pairs of cosmic rays that get correlated by their transport through
+the same realisation of the turbulent magnetic field. We argue that the
+formation of small-scale anisotropies is the reflection of the particular
+realisation of the turbulent magnetic field experienced by cosmic rays on time
+scales intermediate between the early, ballistic regime and the late, diffusive
+regime. We approach this problem in two different ways: First, we run test
+particle simulations in synthetic turbulence, covering for the first time the
+TV rigidities of observations with realistic turbulence parameters. Second, we
+extend the recently introduced mixing matrix approach and determine the
+steady-state angular power spectrum. Throughout, we adopt magneto-static,
+slab-like turbulence. We find excellent agreement between the predicted angular
+power spectra in both approaches over a large range of rigidities. In the
+future, measurements of small-scale anisotropies will be valuable in
+constraining the nature of the turbulent magnetic field in our Galactic
+neighborhood.",2111.06419v1
+2022-03-01,Bianchi Type I model of universe with customized scale factors,"According to standard cosmology, the universe is homogeneous and isotropic at
+large scales. However, some anisotropies can be observed at the local scale in
+the universe through various ways. Here we have studied the Bianchi type I
+model with customizing the scale factors to understand the anisotropic nature
+of the universe. We have considered two cases with slight modifications of
+scale factors in different directions in the generalized Bianchi Type I metric
+equation, and compared the results with the $\Lambda$CDM model and also with
+available cosmological observational data. Through this study, we also want to
+predict the possible degree of anisotropy present in the early universe and its
+evolution to current time by calculating the value of density parameter for
+anisotropy ($\Omega_{\sigma}$) for both low and high redshift (z) along with
+the possible relative anisotropy that exist among different directions. It is
+found that there was a significant amount of anisotropy in the early universe
+and the anisotropic nature of the universe vanishes at the near past and the
+present epochs. Thus at near past and present stages of the universe there is
+no effective distinction between this anisotropic model and the standard
+$\Lambda$CDM model.",2203.00385v2
+2022-03-20,Anisotropy of Magnetic Field Spectra at Kinetic Scales of Solar Wind Turbulence as Revealed by Parker Solar Probe in the Inner Heliosphere,"Using the Parker Solar Probe data taken in the inner heliosphere, we
+investigate the power and spatial anisotropy of magnetic-field spectra at
+kinetic scales (i.e., around sub-ion scales) in solar wind turbulence in the
+inner heliosphere. We find that strong anisotropy of magnetic spectra occurs at
+kinetic scales with the strongest power in the perpendicular direction with
+respect to the local magnetic field (forming an angle theta_B with the mean
+flow velocity). The spectral index of magnetic spectra varies from -3.2 to -5.8
+when the angle theta_B changes from 90 to 180 (or 0) deg, indicating that
+strong anisotropy of the spectral indices occurs at kinetic scales in the solar
+wind turbulence. Using a diagnosis based on the magnetic helicity, we show that
+the anisotropy of the spectral indices can be explained by the nature of the
+plasma modes that carry the cascade at kinetic scales. We discuss our findings
+in light of existing theories and current development in the field.",2203.10475v1
+2022-03-25,Phase diagrams and excitations of anisotropic $S=1$ quantum magnets on the triangular lattice,"The $S=1$ bilinear-biquadratic Heisenberg exchange model on the triangular
+lattice with a single-ion anisotropy has previously been shown to host a number
+of exotic magnetic and nematic orders [Moreno-Cardoner $\textit{et al.}$, Phys.
+Rev. B $\textbf{90}$, 144409 (2014)], including an extensive region of
+""supersolid"" order. In this work, we amend the model by an XXZ anisotropy in
+the exchange interactions. Tuning to the limit of an exactly solvable $S=1$
+generalized Ising-/Blume-Capel-type model provides a controlled limit to access
+phases at finite transverse exchange. Notably, we find an additional
+macroscopically degenerate region in the phase diagram and study its fate under
+perturbation theory. We further map out phase diagrams as a function of the XXZ
+anisotropy parameter, ratio of bilinear and biquadratic interactions and
+single-ion anisotropy, and compute corrections to the total ordered moment in
+various phases using systematically constructed linear flavor-wave theory. We
+also present linear flavor-wave spectra of various states, finding that the
+lowest-energy band in three-sublattice generalized (i.e. with $S^z=\pm1,0$)
+Ising/Blume-Capel states, stabilized by strong exchange anisotropies, is
+remarkably flat, opening up the way to flat-band engineering of magnetic
+excitation via stabilizing non-trivial Ising-ordered ground states.",2203.13490v1
+2022-06-20,Forecasting pulsar timing array sensitivity to anisotropy in the stochastic gravitational wave background,"Statistical anisotropy in the nanohertz-frequency gravitational-wave
+background (GWB) is expected to be detected by pulsar timing arrays (PTAs) in
+the near future. By developing a frequentist statistical framework that
+intrinsically restricts the GWB power to be positive, we establish scaling
+relations for multipole-dependent anisotropy decision thresholds that are a
+function of the noise properties, timing baselines, and cadences of the pulsars
+in a PTA. We verify that $(i)$ a larger number of pulsars, and $(ii)$ factors
+that lead to lower uncertainty on the cross-correlation measurements between
+pulsars, lead to a higher overall GWB signal-to-noise ratio, and lower
+anisotropy decision thresholds with which to reject the null hypothesis of
+isotropy. Using conservative simulations of realistic NANOGrav datasets, we
+predict that an anisotropic GWB with angular power $C_{l=1} > 0.3\,C_{l=0}$ may
+be sufficient to produce tension with isotropy at the $p = 3\times10^{-3}$
+($\sim3\sigma$) level in near-future NANOGrav data with a $20$~yr baseline. We
+present ready-to-use scaling relationships that can map these thresholds to any
+number of pulsars, configuration of pulsar noise properties, and sky coverage.
+We discuss how PTAs can improve the detection prospects for anisotropy, as well
+as how our methods can be adapted for more versatile searches.",2206.09936v1
+2022-06-28,Probing parity-odd bispectra with anisotropies of GW $V$ modes,"It is well known that non-trivial squeezed tensor bispectra can lead to
+anisotropies in the inflationary stochastic gravitational wave (GW) background,
+providing us with an alternative and complementary window to primordial
+non-Gaussianities (NGs) with respect to the CMB. Previous works have
+highlighted the detection prospects of parity-even tensor NGs via the GW
+$I$-mode anisotropies. In this work we extend this by analysing for the first
+time the additional information carried by GW $V$-mode anisotropies due to
+squeezed NGs. We show that GW $V$ modes allow us to probe parity-odd squeezed
+$\langle \rm tts \rangle$ and $\langle \rm ttt \rangle$ bispectra. These
+bispectra break parity at the non-linear level and can be introduced by
+allowing alternative symmetry breaking patterns during inflation, like those
+comprised in solid inflation. Considering a BBO-like experiment, we find that a
+non-zero detection of squeezed $\langle \rm tts \rangle$ parity-odd bispectra
+in the $V$ modes dipole is possible without requiring any short-scale
+enhancement of the GW power spectrum amplitude over the constraints set by the
+CMB. We also briefly discuss the role of $V$-CMB cross-correlations. Our work
+can be extended in several directions and motivates a systematic search for
+polarized GW anisotropies in the next generations of GW experiments.",2206.14173v3
+2022-07-23,Large-scale anisotropies of extragalactic cosmic rays below the ankle,"We study the anisotropies on large angular scales which can be present in the
+flux of cosmic rays reaching the Earth from a population of extragalactic
+sources, focusing on the energy range between the second knee and the ankle. In
+this energy range the particles are significantly affected by the Galactic
+magnetic field, which then plays a relevant role in shaping the expected
+anisotropies. The Galactic magnetic field deflects the cosmic-ray trajectories
+and thus modifies the anisotropies present outside the halo of the Galaxy, in
+particular the dipolar one associated with the translational motion of the
+observer (Compton-Getting effect). Also, due to the Galactic rotation, in the
+reference frame of an observer at Earth there is an electric component of the
+Galactic field that produces a small change in the particles' momentum. This
+acceleration depends on the cosmic-ray arrival direction and it hence induces
+anisotropies in the flux observed in a given energy range. We analyse the
+expected amplitude and phase of the resulting dipolar component of the flux and
+discuss the possibility to explain via these effects the change in the phase of
+the right-ascension distribution which is observed at energies around 1 EeV.",2207.11540v2
+2022-09-30,Induced cosmological anisotropy by a gauge-gravity interaction,"We present a simple model which generates cosmological anisotropies on top of
+standard FLRW geometry. This is in some sense reminiscent of the mean field
+approximation, where the mean field cosmological model under consideration
+would be the standard FLRW, and the anisotropy is a small perturbative
+correction on top of it. Using a supergravity-inspired model, we confirm that
+the stable fixed point of our model corresponds to standard FLRW cosmology. We
+use a Bianchi VII$_0$-type model supplemented with a scalar and $U(1)$ gauge
+fields, and we show that the anisotropies of the geometry are generated by the
+non-trivial interaction between the gravity sector and the $U(1)$ gauge sector.
+Studying the attractor flow, we show that the anisotropies are present at early
+times (high redshift) and decay asymptotically to an FLRW attractor fixed
+point. With such a mechanism, observations of non-isotropy are not
+contradictory to FLRW geometry or indeed the $\Lambda$CDM model. Such models
+could in principle shed some insights on the present cosmological tensions.",2209.15225v3
+2022-11-24,A Simplified Method of the Assessment of Magnetic Anisotropy of Commonly Used Sapphire Substrates in SQUID Magnetometers,"Solid state wafers are indispensable components in material science as
+substrates for epitaxial homo- or hetero-structures or carriers for
+two-dimensional materials. However, a reliable determination of magnetic
+properties of nanomaterials in volume magnetometry is frequently affected by
+unexpectedly rich magnetism of these substrates, including significant magnetic
+anisotropy. Here, we describe a simplified experimental routine of magnetic
+anisotropy assessment, which we exemplify and validate for epi-ready sapphire
+wafers from various sources. Both the strength and the sign of magnetic
+anisotropy is obtained from carefully designed temperature dependent
+measurements, which mitigate all known pitfalls of volume SQUID magnetometry
+and are substantially faster than traditional approaches. Our measurements
+indicate that in all the samples two types of net paramagnetic contributions
+coexists with diamagnetism. The first one can be as strong as 10% of the base
+diamagnetism of sapphire [-3.7(1) x 10-7 emu/gOe], and, when exceeds 2% mark,
+it exhibits pronounced magnetic anisotropy with the easy axis oriented
+perpendicularly to the face of c-plane wafers. The other is much weaker but
+exhibit ferromagnetic-like appearance. These findings form an important message
+that non-standard magnetism of common substrates can significantly influence
+the results of precise magnetometry of nanoscale materials and its existence
+must be taken for granted by both industry and academia.",2211.13690v1
+2022-12-08,"Thin film epitaxial [111] Co$_{50}$Pt$_{50}$: Structure, magnetisation, and spin polarisation","Ferromagnetic films with perpendicular magnetic anisotropy are of interest in
+spintronics and superconducting spintronics. Perpendicular magnetic anisotropy
+can be achieved in thin ferromagnetic multilayer structures, when the
+anisotropy is driven by carefully engineered interfaces. Devices with multiple
+interfaces are disadvantageous for our application in superconducting
+spintronics, where the current perpendicular to plane is affected by the
+interfaces. Robust intrinsic PMA can be achieved in certain Co$_x$Pt$_{100-x}$
+alloys and compounds at any thickness, without increasing the number of
+interfaces. Here, we grow equiatomic Co$_{50}$Pt$_{50}$ and report a
+comprehensive study on the structural, magnetic, and spin-polarisation
+properties in the $L1_1$ and $L1_0$ ordered compounds. Primarily, interest in
+Co$_{50}$Pt$_{50}$ has been in the $L1_0$ crystal structure, where layers of Pt
+and Co are stacked alternately in the [100] direction. There has been less work
+on $L1_1$ crystal structure, where the stacking is in the [111] direction. For
+the latter $L1_1$ crystal structure, we find magnetic anisotropy perpendicular
+to the film plane. For the former $L1_0$ crystal structure, the magnetic
+anisotropy is perpendicular to the [100] plane, which is neither in-plane or
+out-of-plane in our samples. We obtain a value for the ballistic spin
+polarisation of the $L1_1$ and $L1_0$ Co$_{50}$Pt$_{50}$ to be $47\pm3\%$.",2212.04370v2
+2023-02-01,Temperature-independent ferromagnetic resonance shift in Bi-doped YIG garnets through magnetic anisotropy tuning,"Thin garnet films are becoming central for magnon-spintronics and
+spin-orbitronics devices as they show versatile magnetic properties together
+with low magnetic losses. These fields would benefit from materials in which
+heat does not affect the magnetization dynamics, an effect known as the
+non-linear thermal frequency shift. In this study, low damping Bi substituted
+Iron garnet (Bi:YIG) ultra-thin films have been grown using Pulsed Laser
+Deposition. Through a fine tuning of the growth parameters, the precise control
+of the perpendicular magnetic anisotropy allows to achieve a full compensation
+of the dipolar magnetic anisotropy. Strikingly, once the growth conditions are
+optimized, varying the growth temperature from 405 {\deg}C to 475 {\deg}C as
+the only tuning parameter induces the easy-axis to go from out-of-plane to
+in-plane. For films that are close to the dipolar compensation, Ferromagnetic
+Resonance measurements yield an effective magnetization $\mu _{0}M_{eff} (T)$
+that has almost no temperature dependence over a large temperature range (260 K
+to 400 K) resulting in an anisotropy temperature exponent of 2. These findings
+put Bi:YIG system among the very few materials in which the temperature
+dependence of the magnetic anisotropy varies at the same rate than the
+saturation magnetization. This interesting behavior is ascribed
+phenomenologically to the sizable orbital moment of $Bi^{3+}$.",2302.00585v1
+2023-02-17,Significantly increased magnetic anisotropy in Co nano-columnar multilayer structure via a unique sequential oblique-normal deposition approach,"Oblique/normal sequential deposition technique is used to create Co based
+unique multilayer structure [Co-oblique(4.4nm)/Co-normal (4.2 nm)]x10, where
+each Co-oblique layer is deposited at an oblique angle of 75deg, to induce
+large in-plane uniaxial magnetic anisotropy (UMA). Compared to the previous
+ripple, stress and oblique angle deposition (OAD) related studies on Cobalt in
+literature, one-order higher UMA with the easy axis of magnetization along the
+projection of the tilted nano-columns in the multilayer plane is observed. The
+multilayer retains magnetic anisotropy even after annealing at 450C. The
+in-plane UMA in this multilayer is found to be the combination of shape, and
+magneto-crystalline anisotropy (MCA) confirmed by the temperature-dependent
+grazing incidence small angle X-ray scattering (GISAXS), in situ reflection
+high energy electron diffraction (RHEED) and grazing incidence X-ray
+diffraction (GIXRD) measurements. The crystalline texturing of hcp Co in the
+multilayer minimizes spin-orbit coupling energy along the column direction,
+which couples with the shape anisotropy energies and results in preferential
+orientation of the easy magnetic axis along the projection of the columns in
+the multilayer plane. Reduction in UMA after annealing is attributed to
+diffusion/merging of columns and annihilating crystallographic texturing. The
+obtained one-order high UMA demonstrates the potential application of the
+unique structure engineering technique, which may have far-reaching advantages
+in magnetic thin films/multilayers and spintronic devices.",2302.08739v1
+2023-04-30,Feedback-driven anisotropy in the circumgalactic medium for quenching galaxies in the SIMBA simulations,"We use the SIMBA galaxy formation simulation suite to explore anisotropies in
+the properties of circumgalactic gas that result from accretion and feedback
+processes. We particularly focus on the impact of bipolar active galactic
+nuclei (AGN) jet feedback as implemented in SIMBA, which quenches galaxies and
+has a dramatic effect on large-scale gas properties. We show that jet feedback
+at low redshifts is most common in the stellar mass range $(1-5)\times
+10^{10}M_\odot$, so we focus on galaxies with active jets in this mass range.
+In comparison to runs without jet feedback, jets cause lower densities and
+higher temperatures along the galaxy minor axis (SIMBA jet direction) at radii
+>=$0.5r_{200c}-4r_{200c}$ and beyond. This effect is less apparent at higher or
+lower stellar masses, and is strongest within green valley galaxies. The
+metallicity also shows strong anisotropy out to large scales, driven by star
+formation feedback. We find substantially stronger anisotropy at
+<=$0.5r_{200c}$, but this also exists in runs with no explicit feedback,
+suggesting that it is due to anisotropic accretion. Finally, we explore
+anisotropy in the bulk radial motion of the gas, finding that both star
+formation and AGN wind feedback contribute to pushing the gas outwards along
+the minor axis at <=1 Mpc, but AGN jet feedback further causes bulk outflow
+along the minor axis out to several Mpc, which drives quenching via gas
+starvation. These results provide observational signatures for the operation of
+AGN feedback in galaxy quenching.",2305.00602v2
+2023-05-18,Compass-like manipulation of electronic nematicity in Sr$_3$Ru$_2$O$_7$,"Electronic nematicity has been found in a wide range of strongly correlated
+electron materials, resulting in the electronic states having a symmetry that
+is lower than that of the crystal that hosts them. One of the most astonishing
+examples is Sr$_3$Ru$_2$O$_7$, in which a small in-plane component of a
+magnetic field induces significant resistivity anisotropy. The direction of
+this anisotropy follows the direction of the in-plane field. The microscopic
+origin of this field-induced nematicity has been a long-standing puzzle, with
+recent experiments suggesting a field-induced spin density wave driving the
+anisotropy. Here, we report spectroscopic imaging of a field-controlled
+anisotropy of the electronic structure at the surface of Sr$_3$Ru$_2$O$_7$. We
+track the electronic structure as a function of the direction of the field,
+revealing a continuous change with the angle. This continuous evolution
+suggests a mechanism based on spin-orbit coupling resulting in compass-like
+control of the electronic bands. The anisotropy of the electronic structure
+persists to temperatures about an order of magnitude higher compared to the
+bulk, demonstrating novel routes to stabilize such phases over a wider
+temperature range.",2305.11210v2
+2023-07-12,Quasi-static magnetization dynamics in a compensated ferrimagnetic half-metal -- Mn$_2$Ru$_x$Ga,"Exploring anisotropy and diverse magnetization dynamics in specimens with
+vanishing magnetic moments presents a significant challenge using traditional
+magnetometry, as the low resolution of existing techniques hinders the ability
+to obtain accurate results. In this study, we delve deeper into the examination
+of magnetic anisotropy and quasi-static magnetization dynamics in \mrg\,(MRG)
+thin films, as an example of a compensated ferrimagnetic half-metal, by
+employing anomalous Hall effect measurements within a tetragonal crystal
+lattice system. Our research proposes an innovative approach to accurately
+determine the complete set of anisotropy constants of these MRG thin films. To
+achieve this, we perform anomalous Hall voltage curve fitting, using torque
+models under the macrospin approximation, which allow us to obtain out-of-plane
+anisotropy constants $K_1=4.0\times10^4$ J m$^{-3}$ ($K_1/M=0.655$\,T) and
+$K_2=2.54\times10^4$ J m$^{-3}$ ($K_2/M=0.416$\,T), along with a weaker
+in-plane anisotropy constant $K_3=3.48\times10^3$ J m$^{-3}$
+($K_3/M=0.057$\,T). By additionally employing first-order reversal curves
+(FORC) and classical Preisach hysteresis (hysterons) models, we are able to
+validate the efficacy of the macrospin model in capturing the magnetic behavior
+of MRG thin films. Furthermore, our investigation substantiates that the
+complex quasi-static magnetization dynamics of MRG thin films can be
+effectively modelled using a combination of hysteronic and torque models. This
+approach facilitates the exploration of both linear and non-linear quasi-static
+magnetization dynamics, in the presence of external magnetic field and/or
+current-induced effective fields, generated by the spin-orbit torque and spin
+transfer torque mechanisms.",2307.06403v1
+2023-08-11,Piezostrain-induced in-plane anisotropy of superconducting transition temperature for FeSe0.5Te0.5 thin films,"Superconductivity is a macroscopic quantum phenomenon and it is commonly
+believed that the in-plane superconducting transition temperature (Tc) should
+be isotropic for superconductors with crystal structures of stacking layers
+(quasi two-dimensional). Here, we report the observation of piezostrain-induced
+in-plane anisotropy of Tc in FeSe0.5Te0.5 (FST) thin films grown on
+ferroelectrics. The as-prepared FST shows tetragonal phase with equal in-plane
+lattice parameters and absence of in-plane anisotropy of Tc. Upon applying
+electric fields, piezostrain induces difference of the in-plane lattice
+parameters (a-b) and in-plane anisotropy of Tc. The in-plane anisotropy of Tc
+correlates with a-b and becomes more remarkable for larger values of a-b. Some
+possible extrinsic effects were ruled out by experiments and analysis. It is
+suggested that electronic nematicity with one direction induced by piezostrain
+and inhomogeneous superconductivity in FST are involved in this unusual
+phenomenon. This work reveals the exotic behavior of FST and will stimulate
+exploration of similar behavior in other unconventional superconductors.",2308.05919v1
+2023-09-22,Influence of surface energy anisotropy on nucleation and crystallographic texture of polycrystalline deposits,"This paper aims to elucidate the role of interface energy anisotropy in
+orientation selection during nucleation of new grains in a polycrystalline film
+growth. An assessment of (heterogeneous) nucleation probability as function of
+orientation of both the bottom grain and of the nucleus was developed (using
+the concepts of classical nucleation theory). Novel solutions to the
+generalized Winterbottom construction were described in cases of very strong
+anisotropy and arbitrary orientations. In order to demonstrate the effect on
+the film crystallographic texture, a 2D Monte Carlo algorithm for anisotropic
+polycrystalline growth was used to simulate growth of films with columnar
+microstructure. The effect of strength of anisotropy, the deposition rate and
+initial texture were investigated. Results showed that with larger strength of
+anisotropy, the nucleation rate is less dependent on the driving force, but
+more dependent on the initial texture. With certain initial textures, the
+anisotropic nucleation may even be either impossible or having probability
+close to one irrespective of the driving force. Depending on the conditions,
+the anisotropic nucleation could hasten the evolution towards the
+interface-energy minimizing texture or retard it. Based on these insights, a
+hypothesis was offered to explain a peculiar texture evolution in
+electrodeposited nickel.",2309.12889v2
+2023-10-24,Spin wave excitations in low dimensional systems with large magnetic anisotropy,"The low energy excitation spectrum of a two-dimensional ferromagnetic
+material is dominated by single-magnon excitations that show a gapless
+parabolic dispersion relation with the spin wave vector. This occurs as long as
+magnetic anisotropy and anisotropic exchange are negligible compared to
+isotropic exchange. However, to maintain magnetic order at finite temperatures,
+it is necessary to have sizable anisotropy to open a gap in the spin wave
+excitation spectrum. We consider four real two-dimensional systems for which
+ferromagnetic order at finite temperature has been observed or predicted.
+Density functional theory calculations of the total energy differences for
+different spin configurations permit us to extract the relevant parameters and
+connect them with a spin Hamiltonian. The corresponding values of the Curie
+temperature are estimated using a simple model and found to be mostly
+determined by the value of the isotropic exchange. The exchange and anisotropy
+parameters are used in a toy model of finite-size periodic chains to study the
+low-energy excitation spectrum, including single-magnon and two-magnon
+excitations. At low energies we find that single-magnon excitations appear in
+the spectrum together with two-magnon excitations. These excitations present a
+gap that grows particularly for large values of the magnetic anisotropy or
+anisotropic exchange, relative to the isotropic exchange.",2310.15942v1
+2023-10-26,Pitch-Angle Anisotropy Imprinted by Relativistic Magnetic Reconnection,"Radiation emitted by nonthermal particles accelerated during relativistic
+magnetic reconnection is critical for understanding the nonthermal emission in
+a variety of astrophysical systems, including blazar jets, black hole coronae,
+pulsars, and magnetars. By means of fully kinetic Particle-in-Cell (PIC)
+simulations, we demonstrate that reconnection-driven particle acceleration
+imprints an energy-dependent pitch-angle anisotropy and gives rise to broken
+power laws in both the particle energy spectrum and the pitch-angle anisotropy.
+The particle distributions depend on the relative strength of the
+non-reconnecting (guide field) versus the reconnecting component of the
+magnetic field ($B_g/B_0$) and the lepton magnetization ($\sigma_0$). Below the
+break Lorentz factor $\gamma_0$ (injection), the particle energy spectrum is
+ultra-hard ($p_< < 1$), while above $\gamma_0$, the spectral index $p_>$ is
+highly sensitive to $B_g/B_0$. Particles' velocities align with the magnetic
+field, reaching minimum pitch angles $\alpha$ at a Lorentz factor $\gamma_{\min
+\alpha}$ controlled by $B_g/B_0$ and $\sigma_0$. The energy-dependent
+pitch-angle anisotropy, evaluated through the mean of $\sin^2 \alpha$ of
+particles at a given energy, exhibits power-law ranges with negative ($m_<$)
+and positive ($m_>$) slopes below and above $\gamma_{\min \alpha}$, becoming
+steeper as $B_g/B_0$ increases. The generation of anisotropic pitch angle
+distributions has important astrophysical implications. We address their
+effects on regulating synchrotron luminosity, spectral energy distribution,
+polarization, particle cooling, the synchrotron burnoff limit, emission
+beaming, and temperature anisotropy.",2310.17560v2
+2023-12-05,Constraints on UHECR sources and extragalactic magnetic fields from directional anisotropies,"A dipole anisotropy in ultra-high-energy cosmic ray (UHECR) arrival
+directions, of extragalactic origin, is now firmly established at energies E >
+8 EeV. Furthermore, the UHECR angular power spectrum shows no power at smaller
+angular scales than the dipole, apart from hints of possible individual hot or
+warm spots for energy thresholds $\gtrsim$40 EeV. Here, we exploit the
+magnitude of the dipole and the limits on smaller-scale anisotropies to place
+constraints on two quantities: the extragalactic magnetic field (EGMF) and the
+number density of UHECR sources or the volumetric event rate if UHECR sources
+are transient. We also vary the bias between the extragalactic matter and the
+UHECR source densities, reflecting whether UHECR sources are preferentially
+found in over- or under-dense regions, and find that little or no bias is
+favored. We follow Ding et al. (2021) in using the Cosmic Flows 2 density
+distribution of the local universe as our baseline distribution of UHECR
+sources, but we improve and extend that work by employing an accurate and
+self-consistent treatment of interactions and energy losses during propagation.
+Deflections in the Galactic magnetic field are treated using both the full JF12
+magnetic field model, with random as well as coherent components, or just the
+coherent part, to bracket the impact of the GMF on the dipole anisotropy. This
+Large Scale Structure (LSS) model gives good agreement with both the direction
+and magnitude of the measured dipole anisotropy and forms the basis for
+simulations of discrete sources and the inclusion of EGMF effects.",2312.02645v3
+2023-12-08,Role of initial transverse momentum in a hybrid approach,"The purpose of this work is to study the effect of exchanging initial
+condition models in a modular hybrid approach. The focus lies on the
+event-by-event correlations of elliptic and triangular flow. This study is
+performed in the hybrid approach SMASH-vHLLE, composed of the hadronic
+transport approach SMASH and the (3+1)d viscous hydrodynamic code vHLLE. The
+initial condition models investigated are SMASH IC, Trento and IP-Glasma.
+Correlations are calculated on an event-by-event basis between the
+eccentricities and momentum anisotropies of the initial state as well as the
+momentum anisotropies in the final state, both for ultra-central and
+off-central collisions for AuAu collisions at $\sqrt{s_{NN}} = 200$ GeV. This
+work demonstrates that, although averaged values for the eccentricities of
+these models are very similar, substantial differences exist both in the
+distributions of eccentricities, the correlations amongst the initial state
+properties as well as in the correlations between initial state and final state
+properties. Notably, whereas initial state momentum anisotropy is shown to not
+affect the final state flow, the presence of radial flow affects the emergence
+of final state momentum anisotropies. Inclusion of radial flow in the linear
+fit improves the prediction of final state flow from initial state properties.
+The presence of momentum in the initial state has an effect on the emergence of
+flow and is therefore a relevant part of initial state models, challenging the
+common understanding of final state momentum anisotropies being a linear
+response to initial state eccentricity only.",2312.05001v1
+2024-01-06,From ergodicity to Stark many-body localization in spin chains with single-ion anisotropy,"The principles of ergodicity and thermalization constitute the foundation of
+statistical mechanics, positing that a many-body system progressively loses its
+local information as it evolves. Nevertheless, these principles can be
+disrupted when thermalization dynamics lead to the conservation of local
+information, as observed in the phenomenon known as many-body localization.
+Quantum spin chains provide a fundamental platform for exploring the dynamics
+of closed interacting quantum many-body systems. This study explores the
+dynamics of a spin chain with $S\geq 1/2$ within the Majumdar-Ghosh model,
+incorporating a non-uniform magnetic field and single-ion anisotropy. Through
+the use of exact numerical diagonalization, we unveil that a nearly
+constant-gradient magnetic field suppress thermalization, a phenomenon termed
+Stark many-body localization (SMBL), previously observed in $S=1/2$ chains.
+Furthermore, our findings reveal that the sole presence of single-ion
+anisotropy is sufficient to prevent thermalization in the system.
+Interestingly, when the magnitudes of the magnetic field and anisotropy are
+comparable, they compete, favoring delocalization. Despite the potential
+hindrance of SMBL by single-ion anisotropy in this scenario, it introduces an
+alternative mechanism for localization. Our interpretation, considering local
+energetic constraints and resonances between degenerate eigenstates, not only
+provides insights into SMBL but also opens avenues for future experimental
+investigations into the enriched phenomenology of disordered free localized
+$S\geq 1/2$ systems.",2401.03111v1
+2024-01-08,On using the counting method to constrain the anisotropy of kilonova radiation,"A large number of binary neutron star (BNS) mergers are expected to be
+detected by gravitational wave (GW) detectors and the electromagnetic (EM)
+counterparts (e.g., kilonovae) of a fraction of these mergers may be detected
+in multi-bands by large area survey telescopes. For a given number of BNS
+mergers detected by their GW signals, the expected numbers of their EM
+counterparts that can be detected by a survey with given selection criteria
+depend on the kilonova properties, including the anisotropy. In this paper, we
+investigate whether the anisotropy of kilonova radiation and the kilonova model
+can be constrained statistically by the counting method, i.e., using the
+numbers of BNS mergers detected via GW and multi-band EM signals. Adopting
+simple models for the BNS mergers, afterglows, and a simple two (blue and
+red)-component model for kilonovae, we generate mock samples for GW detected
+BNS mergers, their associated kilonovae and afterglows detected in multi-bands.
+By assuming some criteria for searching the EM counterparts, we simulate the
+observations of these EM counterparts and obtain the EM observed samples in
+different bands. With the numbers of BNS mergers detected by GW detectors and
+EM survey telescopes in different bands, we show that the anisotropy of
+kilonova radiation and the kilonova model can be well constrained by using the
+Bayesian analysis. Our results suggest that the anisotropy of kilonova
+radiation may be demographically and globally constrained by simply using the
+detection numbers of BNS mergers by GW detectors and EM survey telescopes in
+multi-bands.",2401.03710v1
+2024-01-24,Reversible out-of-plane to in-plane magnetic transition by electrical and thermal cycling in Ni$_{90}$Fe$_{10}$/BaTiO$_3$(001),"The study investigates the manipulation of the magnetic anisotropy in a thick
+(1 $\mu$m) Ni$_{90}$Fe$_{10}$ layer electrodeposited on a ferroelectric
+BaTiO$_3$(001) substrate, using a combination of Magneto-optical Kerr Effect,
+Photoemission Electron Microscopy with X-ray circular magnetic dichroism and
+X-ray diffraction. In the as-grown state, the system shows weak perpendicular
+magnetic anisotropy and characteristic stripe domains. Upon out-of-plane
+electrical poling of the BaTiO$_3$ substrate, the magnetic anisotropy switches
+to in-plane with a strong uniaxial behavior. This change is ascribed to the
+magnetoelastic effect due to the switching of the BaTiO$_3$ ferroelectric [001]
+axis into the sample plane, as evidenced by XRD. The strong mechanical
+interaction with the thick Ni$_{90}$Fe$_{10}$ overlayer prevents the full
+inversion of the substrate. The perpendicular magnetic anisotropy can be
+recovered by a mild thermal annealing above the BaTiO$_3$ tetrahedral to cubic
+phase transition and can be cycled by repeated electrical poling/thermal
+annealing. This method opens the path to a reversible control of the magnetic
+anisotropy in Ni$_{90}$Fe$_{10}$/BaTiO$_3$ heterostructures from perpendicular
+to in-plane.",2401.13487v2
+2024-01-29,Superexchange interactions and magnetic anisotropy in MnPSe$_3$ monolayer,"Two-dimensional van der Waals magnetic materials are of great current
+interest for their promising applications in spintronics. In this work, using
+density functional theory calculations in combination with the maximally
+localized Wannier functions method and the magnetic anisotropy analyses, we
+study the electronic and magnetic properties of MnPSe$_3$ monolayer. Our
+results show that it is a charge transfer antiferromagnetic (AF) insulator. For
+this Mn$^{2+}$ $3d^5$ system, although it seems straightforward to explain the
+AF ground state using the direct exchange, we find that the near 90$^\circ$
+Mn-Se-Mn charge transfer type superexchange plays a dominant role in
+stabilizing the AF ground state. Moreover, our results indicate that although
+the shape anisotropy favors an out-of-plane spin orientation, the spin-orbit
+coupling (SOC) leads to the experimentally observed in-plane spin orientation.
+We prove that the actual dominant contribution to the magnetic anisotropy comes
+from the second-order perturbation of the SOC, by analyzing its distribution
+over the reciprocal space. Using the AF exchange and anisotropy parameters
+obtained from our calculations, our Monte Carlo simulations give the N\'eel
+temperature $T_{\rm N}=47$ K for MnPSe$_3$ monolayer, which agrees with the
+experimental 40 K. Furthermore, our calculations show that under a uniaxial
+tensile (compressive) strain, N\'eel vector would be parallel (perpendicular)
+to the strain direction, which well reproduces the recent experiments. We also
+predict that $T_{\rm N}$ would be increased by a compressive strain.",2401.16154v1
+2024-02-05,The nonflow issue in connecting anisotropy measurements to hydrodynamics in relativistic heavy-ion collisions,"Hydrodynamics can describe majority of the measured azimuthal anisotropies in
+relativistic heavy-ion collisions. Many of the anisotropy measurements are
+contaminated by nonflow correlations (i.e., those unrelated to global
+event-wise correlations). Those nonflow contamination can cause incorrectness
+or compromise the accuracy of the physics extracted from data-hydrodynamics
+comparison, particularly when one relies on subtle difference in the
+measurements. In the recent preprint by STAR (arXiv:2401.06625) extracting the
+Uranium nucleus deformation parameter, nonflow contamination is assessed by
+subevents in the limited STAR acceptance. In this note, we demonstrate that
+such assessment is inadequate and illustrate how large an effect nonflow can
+cause by using the HIJING model, in which all correlations are nonflow and
+non-hydrodynamic. We thereby conclude that the extracted Uranium deformation
+parameter is premature and emphasize the importance of an earnest assessment of
+or correction for nonflow contamination, not only for this STAR analysis but
+more generally for studies relying on comparing anisotropy measurements to
+hydrodynamic calculations.",2402.03222v1
+2024-02-07,Anisotropy of Density Fluctuations in the Solar Wind at 1 au,"A well-known property of solar wind plasma turbulence is the observed
+anisotropy of the autocorrelations, or equivalently the spectra, of velocity
+and magnetic field fluctuations. Here we explore the related but apparently not
+well-studied issue of the anisotropy of plasma density fluctuations in the
+energy-containing and inertial ranges of solar wind turbulence. Using 10 years
+(1998-2008) of in situ data from the Advanced Composition Explorer (ACE)
+mission, we find that the density correlation scale is slightly larger in
+directions quasi-parallel to the large-scale mean magnetic field as compared to
+quasi-perpendicular directions. The effect is present in both fast and slow
+winds. The anisotropy as a function of the level of correlation is also
+explored. We find at small correlation levels, i.e., at energy-containing
+scales and larger, the density fluctuations are close to isotropy, but in fact
+slightly favor more rapid decorrelation in perpendicular directions. At
+relatively smaller turbulence inertial range scales where the correlation
+values are larger, the sense of anisotropy is reversed in all speed ranges,
+implying a more ``slab-like'' structure, especially prominent in the fast wind
+samples. We contrast this finding with published results on velocity and
+magnetic field correlations.",2402.05191v1
+2024-02-12,Jet Suppression and Azimuthal Anisotropy from RHIC to LHC,"Azimuthal anisotropies of high-$p_T$ particles produced in heavy-ion
+collisions are understood as an effect of a geometrical selection bias.
+Particles oriented in the direction in which the QCD medium formed in these
+collisions is shorter, suffer less energy loss, and thus, are over-represented
+in the final ensemble compared to those oriented in the direction in which the
+medium is longer. In this work we present the first semi-analytical
+predictions, including propagation through a realistic, hydrodynamical
+background, of the azimuthal anisotropies for jets, obtaining a quantitative
+agreement with available experimental data as function of the jet $p_T$, its
+cone size $R$ and the collisions centrality. Jets are multi-partonic, extended
+objects and their energy loss is sensitive to substructure fluctuations. This
+is determined by the physics of color coherence that relates to the ability of
+the medium to resolve those partonic fluctuations. Namely, color dipoles whose
+angle is smaller than a critical angle, $\theta_c$, are not resolved by the
+medium and they effectively act as a coherent source of energy loss. We find
+that jet azimuthal anisotropies have a specially strong dependence on coherence
+physics due to the marked length-dependence of $\theta_c$. By combining our
+predictions for the collision systems and center of mass energies studied at
+RHIC and the LHC, covering a wide range of typical values of $\theta_c$, we
+show that the relative size of jet azimuthal anisotropies for jets with
+different cone-sizes $R$ follow a universal trend that indicates a transition
+from a coherent regime of jet quenching to a decoherent regime. These results
+suggest a way forward to reveal the role played by the physics of jet color
+decoherence in probing deconfined QCD matter.",2402.07869v1
+2024-03-23,The role of rare-earth atoms in the anisotropy and antiferromagnetic exchange coupling at a hybrid metal-organic interface,"Magnetic anisotropy and magnetic exchange interactions are crucial parameters
+that characterize the hybrid metal-organic interface, key component of an
+organic spintronic device. We show that the incorporation of 4$f$ RE atoms to
+hybrid metal-organic interfaces of CuPc/REAu$_2$ type (RE= Gd, Ho) constitutes
+a feasible approach towards on-demand magnetic properties and functionalities.
+The GdAu$_2$ and HoAu$_2$ substrates differ in their magnetic anisotropy
+behavior. Remarkably, the HoAu$_2$ surface boosts the inherent out-of-plane
+anisotropy of CuPc, owing to the match between the anisotropy axis of substrate
+and molecule. Furthermore, the presence of RE atoms leads to a spontaneous
+antiferromagnetic (AFM) exchange coupling at the interface, induced by the
+3$d$-4$f$ superexchange interaction between the unpaired 3$d$ electron of CuPc
+and the 4$f$ electrons of the RE atoms. We show that 4$f$ RE atoms with
+unquenched quantum orbital momentum ($L$), as it is the case of Ho, induce an
+anisotropic interfacial exchange coupling.",2403.15774v1
+2024-04-04,Towards tailored magnetic anisotropy: A first-principles study of L1$_0$ FeNi ultrathin films,"In previous experiments, thin films of L1$\mathrm{_0}$ FeNi with different
+surfaces, including (001), (110) and (111), were produced and studied. Each
+surface defines a different alignment of the crystallographic tetragonal axis
+with respect to the film's plane, resulting in different magnetic anisotropies.
+In this study, we use density functional theory calculations to examine three
+series of L1$\mathrm{_0}$ FeNi films with surfaces (001), (010), and (111), and
+with thicknesses ranging from 0.5 to 3 nm (from 4 to 16 atomic monolayers). Our
+results show that films (001) have perpendicular magnetic anisotropy, while
+(010) favor in-plane magnetization, with a clear preference for the tetragonal
+axis [001]. We propose calling this type of in-plane anisotropy fixed in plane.
+A film with surface (111) and a thickness of four atomic monolayers has the
+magnetization easy axis almost perpendicular to the plane of the film. As the
+thickness of the (111) film increases, the direction of magnetization rotates
+towards a tetragonal axis [001], positioned at an angle of about 45$^{o}$ to
+the plane of the film. Furthermore, the magnetic moment of ultrathin films
+increases by a maximum of 5%, and the most significant changes in spin and
+orbital magnetic moments occur at a depth of about three near-surface atomic
+monolayers. The presented results could be useful for experimental efforts to
+synthesize ultrathin L1$\mathrm{_0}$ FeNi films with different surfaces.
+Ultrathin L1$\mathrm{_0}$ FeNi films with varying magnetic anisotropies may
+find applications in spintronic devices.",2404.03416v1
+1995-12-12,Measurements of Anisotropy in the Cosmic Microwave Background Radiation at 0\fdg5 Scales near the Stars HR5127 and Phi Herculis,"We present measurements of cosmic microwave background (CMB) anisotropy near
+the stars HR5127 and Phi Herculis from the fifth flight of the Millimeter-wave
+Anisotropy eXperiment (MAX). We scanned 8\arcdeg\ strips of the sky with an
+approximately Gaussian 0\fdg5 FWHM beam and a 1\fdg4 peak to peak sinusoidal
+chop. The instrument has four frequency bands centered at 3.5, 6, 9, and
+14~cm$^{-1}$. The IRAS 100~\micron\ map predicts that these two region have low
+interstellar dust contrast. The HR5127 data are consistent with CMB anisotropy.
+The Phi Herculis data, which were measured at lower flight altitudes, show time
+variability at 9 and 14~cm$^{-1}$ which we believe to be due to atmospheric
+emission. However, the Phi Herculis data at 3.5 and 6~cm$^{-1}$ are essentially
+independent of this atmospheric contribution and are consistent with CMB
+anisotropy. Confusion from galactic foregrounds is unlikely based on the
+spectrum and amplitude of the structure at these frequencies. If the observed
+HR5127 structure and the atmosphere independent Phi Herculis structure are
+attributed to CMB anisotropy, then we find $\Delta T/T =
+\langle\frac{l(l+1)C_l}{2\pi}\rangle^{1/2} = 1.2^{+0.4}_{-0.3}\times 10^{-5}$
+for HR5127 and $1.9^{+0.7}_{-0.4}\times 10^{-5}$ for Phi Herculis in the flat
+band approximation. The upper and lower limits represent a 68\% confidence
+interval added in quadrature with a 10\% calibration uncertainty.",9512067v1
+2003-05-02,Two band superconductivity in MgB2: basic anisotropic properties and phase diagram,"Magnesium diboride MgB2 has been an extraordinarily hot research topic since
+the discovery of superconductivity below 40 K, due to the vast amount of
+unusual properties originating from the involvement in superconductivity of two
+sets of bands that are of a different dimensionality. We review, with a strong
+focus on results obtained by torque magnetometry, how this leads to a complex
+behavior of the anisotropic superconducting state properties. The different
+dimensionality of the two sets of bands is manifested in the upper critical
+field Hc2 anisotropy, which was found to strongly decrease with increasing
+temperature. While the angular dependence of Hc2 follows roughly the
+predictions of anisotropic Ginzburg-Landau theory AGLT, small, but systematic
+deviations were observed near Tc. This, and the temperature dependent
+anisotropy, witness a breakdown of the AGLT description of MgB2, even close to
+Tc. Theoretical calculations are in qualitative agreement with the observed
+angle dependence, but suggest a much lower penetration depth anisotropy at low
+temperatures. Reversible torque vs angle curves in the mixed state indicate
+that the penetration depth anisotropy in intermediate fields has to be higher
+than currently available theoretical estimates. The observed field dependent
+effective anisotropies can be accounted for qualitatively by the faster
+depression of superconductivity in the more isotropic bands by the applied
+field. The vortex matter phase diagram is drawn, based on measurements of the
+reversible and irreversible torque in the mixed state. In the irreversible
+torque, a peak effect (PE) was observed in fields of about 0.85 Hc2. History
+effects of the critical current density in the PE region suggest that the PE
+signifies an order-disorder transition of vortex matter.",0305048v2
+2007-08-08,Small-Angle CMB Temperature Anisotropies Induced by Cosmic Strings,"We use Nambu-Goto numerical simulations to compute the cosmic microwave
+background (CMB) temperature anisotropies induced at arcminute angular scales
+by a network of cosmic strings in a Friedmann-Lemaitre-Robertson-Walker (FLRW)
+expanding universe. We generate 84 statistically independent maps on a 7.2
+degree field of view, which we use to derive basic statistical estimators such
+as the one-point distribution and two-point correlation functions. At high
+multipoles, the mean angular power spectrum of string-induced CMB temperature
+anisotropies can be described by a power law slowly decaying as \ell^{-p}, with
+p=0.889 (+0.001,-0.090) (including only systematic errors). Such a behavior
+suggests that a nonvanishing string contribution to the overall CMB
+anisotropies may become the dominant source of fluctuations at small angular
+scales. We therefore discuss how well the temperature gradient magnitude
+operator can trace strings in the context of a typical arcminute
+diffraction-limited experiment. Including both the thermal and nonlinear
+kinetic Sunyaev-Zel'dovich effects, the Ostriker-Vishniac effect, and the
+currently favored adiabatic primary anisotropies, we find that, on such a map,
+strings should be ``eye visible,'' with at least of order ten distinctive
+string features observable on a 7.2 degree gradient map, for tensions U down to
+GU \simeq 2 x 10^{-7} (in Planck units). This suggests that, with upcoming
+experiments such as the Atacama Cosmology Telescope (ACT), optimal
+non-Gaussian, string-devoted statistical estimators applied to small-angle CMB
+temperature or gradient maps may put stringent constraints on a possible cosmic
+string contribution to the CMB anisotropies.",0708.1162v2
+2008-11-04,Sky-maps of the sidereal anisotropy of galactic cosmic ray intensity and its energy dependence,"We analyze the sidereal daily variations observed between 1985 and 2006 at
+Matsushiro, Japan (MAT) and between 1993 and 2005 at Liapootah, Tasmania (LPT).
+These stations comprise the two hemisphere network (THN) of underground muon
+detectors in Japan and Australia. Yearly mean harmonic vectors at MAT and LPT
+are more or less stable without any significant change in phase and amplitude
+in correlation with either the solar activity- or magnetic-cycles. In this
+paper, therefore, we analyze the average anisotropy over the entire observation
+periods, i.e. 1985-2006 for MAT and 1993-2005 for LPT. We apply to the THN data
+a best-fitting analysis based on a model anisotropy in space identical to that
+adopted by Amenomori et al. (2007) for Tibet III data. The median energies of
+primary cosmic rays recorded are ~0.5 TeV for THN and ~5 TeV for the Tibet III
+experiment. It is shown that the intensity distribution of the best-fit
+anisotropy is quite similar to that derived from Tibet III data, regardless of
+the order of magnitude difference in energies of primary particles. This,
+together with the THN observations, confirms that the analysis by Amenomori et
+al. (2007) based on the Tibet III experiment in the northern hemisphere is not
+seriously biased. The best-fit amplitudes of the anisotropy, on the other hand,
+are only one third or less of those reported by the Tibet III experiment,
+indicating attenuation due to solar modulation. The rigidity dependence of the
+anisotropy amplitude in the sub-TeV region is consistent with the spectrum
+reported by Hall et al. (1999), smoothly extending to the Tibet III result in
+the multi-TeV region. The amplitude at higher energies appears almost constant
+or gradually decreasing with increasing rigidity.",0811.0422v2
+2009-07-09,Anisotropy vs chemical composition at ultra-high energies,"This paper proposes and discusses a test of the chemical composition of
+ultra-high energy cosmic rays that relies on the anisotropy patterns measured
+as a function of energy. In particular, we show that if one records an
+anisotropy signal produced by heavy nuclei of charge Z above an energy E_{thr},
+one should record an even stronger (possibly much stronger) anisotropy at
+energies >E_{thr}/Z due to the proton component that is expected to be
+associated with the sources of the heavy nuclei. This conclusion remains robust
+with respect to the parameters characterizing the sources and it does not
+depend at all on the modelling of astrophysical magnetic fields. As a concrete
+example, we apply this test to the most recent data of the Pierre Auger
+Observatory. Assuming that the anisotropy reported above 55EeV is not a
+statistical accident, and that no significant anisotropy has been observed at
+energies <10EeV, we show that the apparent clustering toward Cen A cannot be
+attributed to heavy nuclei. Similar conclusions are drawn regarding the
+apparent excess correlation with nearby active galactic nuclei. We then discuss
+a robust lower bound to the magnetic luminosity that a source must possess in
+order to be able to accelerate particles of charge Z up to 100EeV,
+L_B>10^{45}Z^{-2}erg/s. Using this bound in conjunction with the above
+conclusions, we argue that the current PAO data does not support the model of
+cosmic ray origin in active radio-quiet or even radio-loud galaxies. Finally,
+we demonstrate that the apparent clustering in the direction of Cen A can be
+explained by the contribution of the last few gamma-ray bursts or magnetars in
+the host galaxy thanks to the scattering of the cosmic rays on the magnetized
+lobes.",0907.1354v1
+2010-03-11,Magnetic moment and magnetic anisotropy of linear and zigzag 4{\it d} and 5{\it d} transition metal nanowires: First-principles calculations,"An extensive {\it ab initio} study of the physical properties of both linear
+and zigzag atomic chains of all 4$d$ and 5$d$ transition metals (TM) within the
+GGA by using the accurate PAW method, has been carried out. All the TM linear
+chains are found to be unstable against the corresponding zigzag structures.
+All the TM chains, except Nb, Ag and La, have a stable (or metastable) magnetic
+state in either the linear or zigzag or both structures. Magnetic states appear
+also in the sufficiently stretched Nb and La linear chains and in the largely
+compressed Y and La chains. The spin magnetic moments in the Mo, Tc, Ru, Rh, W,
+Re chains could be large ($\geq$1.0 $\mu_B$/atom). Structural transformation
+from the linear to zigzag chains could suppress the magnetism already in the
+linear chain, induce the magnetism in the zigzag structure, and also cause a
+change of the magnetic state (ferromagnetic to antiferroamgetic or vice verse).
+The calculations including the spin-orbit coupling reveal that the orbital
+moments in the Zr, Tc, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir and Pt chains could be
+rather large ($\geq$0.1 $\mu_B$/atom). Importantly, large magnetic anisotropy
+energy ($\geq$1.0 meV/atom) is found in most of the magnetic TM chains,
+suggesting that these nanowires could have fascinating applications in
+ultrahigh density magnetic memories and hard disks. In particular, giant
+magnetic anisotropy energy ($\geq$10.0 meV/atom) could appear in the Ru, Re,
+Rh, and Ir chains. Furthermore, the magnetic anisotropy energy in several
+elongated linear chains could be as large as 40.0 meV/atom. A
+spin-reorientation transition occurs in the Ru, Ir, Ta, Zr, La and Zr, Ru, La,
+Ta and Ir linear chains when they are elongated. Remarkably, all the 5$d$ as
+well as Tc and Pd chains show the colossal magnetic anisotropy (i.e., it is
+impossible to rotate magnetization into certain directions). Finally, the
+electronic band structure and density of states of the nanowires have also been
+calculated in order to understand the electronic origin of the large magnetic
+anisotropy and orbital magnetic moment as well as to estimate the conduction
+electron spin polarization.",1003.2254v1
+2010-07-12,Simple models for dynamic hysteresis loops calculation: Application to hyperthermia optimization,"To optimize the heating properties of magnetic nanoparticles (MNPs) in
+magnetic hyperthermia applications, it is necessary to calculate the area of
+their hysteresis loops in an alternating magnetic field. The three types of
+theories suitable for describing the hysteresis loops of MNPs are presented and
+compared to numerical simulations: equilibrium functions, Stoner-Wohlfarth
+model based theories (SWMBTs) and linear response theory (LRT). Suitable
+formulas to calculate the hysteresis area of major cycles are deduced from
+SWMBTs and from numerical simulations; the domain of validity of the analytical
+formula is explicitly studied. In the case of minor cycles, the hysteresis area
+calculations are based on the LRT. A perfect agreement between LRT and
+numerical simulations of hysteresis loops is obtained. The domain of validity
+of the LRT is explicitly studied. Formulas to calculate the hysteresis area at
+low field valid for any anisotropy of the MNP are proposed. Numerical
+simulations of the magnetic field dependence of the area show it follows
+power-laws with a large range of exponents. Then, analytical expressions
+derived from LRT and SWMBTs are used for a theoretical study of magnetic
+hyperthermia. It is shown that LRT is only pertinent for MNPs with strong
+anisotropy and that SWMBTs should be used for weak anisotropy MNPs. The optimum
+volume of MNPs for magnetic hyperthermia as function of material and
+experimental parameters is derived. The maximum specific absorption rate (SAR)
+achievable is calculated versus the MNP anisotropy. It is shown that an optimum
+anisotropy increases the SAR and reduces the detrimental effects of size
+distribution. The optimum anisotropy is simple to calculate and depends on the
+magnetic field used in the hyperthermia experiments and on the MNP
+magnetization only. The theoretical optimum parameters are compared to the one
+of several magnetic materials.",1007.2009v2
+2011-05-07,An accurate measurement of the anisotropies and mean level of the Cosmic Infrared Background at 100 and 160 um,"The measurement of the anisotropies in the cosmic infrared background (CIB)
+is a powerful mean of studying the evolution of galaxies and large-scale
+structures. These anisotropies have been measured by a number of experiments,
+from the far-infrared to the millimeter. One of the main impediments to an
+accurate measurement on large scales is the contamination of the foreground
+signal by Galactic dust emission. Our goal is to show that we can remove the
+Galactic cirrus contamination using HI data, and thus accurately measure the
+clustering of starburst galaxies in the CIB. We use observations of the ELAIS
+N1 field at far-infrared (100 and 160{\mu}m) and radio (21 cm) wavelengths. We
+compute the correlation between dust emission, traced by far-infrared
+observations, and HI gas traced by 21cm observations, and derive dust
+emissivities that enable us to subtract the cirrus emission from the
+far-infrared maps. We then derive the power spectrum of the CIB anisotropies,
+as well as its mean level at 100{\mu}m and 160{\mu}m. We also combine the HI
+data and Spitzer total power mode absolute measurements to determine the CIB
+mean level at 160{\mu}m. We find B160=0.77\pm0.04\pm0.12MJy/sr,where the first
+error is statistical and the second systematic. Combining this measurement with
+the B100/B160 color of the correlated anisotropies, we also derive the CIB mean
+at 100 {\mu}m, B100=0.24\pm0.08\pm0.04 MJy/sr. This measurement is in line with
+values obtained with recent models of infrared galaxy evolution and
+Herschel/PACS data, but is much smaller than the previous DIRBE measurements.
+The use of high-angular resolution Hi data is mandatory to accurately
+differentiate the cirrus from the CIB emission. The 100 {\mu}m IRAS map (and
+thus the map developed by Schlegel and collaborators) in such extragalactic
+fields is highly contaminated by the CIB anisotropies and hence cannot be used
+as a Galactic cirrus tracer.",1105.1463v3
+2011-06-29,Profiles of Dark Matter Velocity Anisotropy in Simulated Clusters,"We report statistical results for dark matter (DM) velocity anisotropy,
+\beta, from a sample of some 6000 cluster-size halos (at redshift zero)
+identified in a \Lambda CDM hydrodynamical adaptive mesh refinement simulation
+performed with the Enzo code. These include profiles of \beta\ in clusters with
+different masses, relaxation states, and at several redshifts, modeled both as
+spherical and triaxial DM configurations. Specifically, although we find a
+large scatter in the DM velocity anisotropy profiles of different halos (across
+elliptical shells extending to at least ~$1.5 r_{vir}$), universal patterns are
+found when these are averaged over halo mass, redshift, and relaxation stage.
+These are characterized by a very small velocity anisotropy at the halo center,
+increasing outward to about 0.27 and leveling off at about $0.2 r_{vir}$.
+Indirect measurements of the DM velocity anisotropy fall on the upper end of
+the theoretically expected range. Though measured indirectly, the estimations
+are derived by using two different surrogate measurements - X-ray and galaxy
+dynamics. Current estimates of the DM velocity anisotropy are based on very
+small cluster sample. Increasing this sample will allow testing theoretical
+predictions, including the speculation that the decay of DM particles results
+in a large velocity boost. We also find, in accord with previous works, that
+halos are triaxial and likely to be more prolate when unrelaxed, whereas
+relaxed halos are more likely to be oblate. Our analysis does not indicate that
+there is significant correlation (found in some previous studies) between the
+radial density slope, \gamma, and \beta\ at large radii, $0.3 r_{vir} < r <
+r_{vir}$.",1106.6048v2
+2012-09-26,Radioactivity and fragmentation of UHECR: Correlating gamma anisotropy and neutrino PeV events,"UHECR (Ultra High Energy Cosmic Rays) were expected to be protons, to fly
+straight and to suffer from a GZK (opacity on CMB radiation) cut off. AUGER
+suggested in 2007 that such early UHECR anisotropy was compatible with the
+foreseen Super-Galactic plane, while both HIRES and AUGER confirmed this
+apparent GZK cut-off in the spectra. However, the same AUGER composition since
+2007 had favored nuclei (and not nucleons). The recent absence of narrow angle
+clustering in UHECR maps, as it should be expected for protons, the missing of
+events along the nearest Cluster Virgo, the wide spread (nearly 16 degree
+angle) of UHECR along Cen A are in disagreement with the first proton-UHECR
+AUGER understanding. Since 2008 we had claimed a light nuclei role for the Cen
+A crowded area. However the ICECUBE absence of TeV neutrino clustering or
+anisotropy, its spectra steepening favors mostly a ruling atmospheric neutrino
+noise up to tens TeV. However two recent PeV neutrino event, cannot easily
+coexist or been extrapolated with such an atmospheric ruling scenario, or with
+GZK (either nucleons or nuclei) secondary expected spectra. Finally tens of TeV
+gamma anisotropy in ARGO-MILAGRO-ICECUBE maps may hardly be associated with
+known hadronic sources. We imagine such anisotropy ruled by diffused gamma
+secondaries, shining along UHECR bending and flight: radioactive (Ni,Co,Al,D,
+neutron) light and heavy UHECR nuclei in GRB-SGRs-jet, while scattering or
+decaying in flight, may paint in the sky (by gamma, electrons and neutrinos
+secondaries) their trajectories and bending, connecting UHECR spread events
+with TeV anisotropy, and also offering a very realistic source of first,
+otherwise puzzling, observed PeV neutrinos. Evidences for such relativistic Ni
+jet in 4U1630-47 system has been observed recently by D\'iaz Trigo
+collaboration.",1209.6090v3
+2013-03-08,Orbital anisotropy in cosmological haloes revisited,"The velocity anisotropy of particles inside dark matter (DM) haloes is an
+important physical quantity, which is required for the accurate modelling of
+mass profiles of galaxies and clusters of galaxies. It is typically measured
+using the ratio of the radial-to-tangential velocity dispersions at a given
+distance from the halo centre. However, this measure is insufficient to
+describe the dynamics of realistic haloes, which are typically quite elongated.
+Studying the velocity distribution in massive DM haloes in cosmological
+simulations, we find that in the inner parts of the haloes the local velocity
+ellipsoids are strongly aligned with the major axis of the halo, the alignment
+being stronger for more relaxed haloes. In the outer regions of the haloes, the
+alignment becomes gradually weaker and the orientation is more random. These
+two distinct regions of different degree of the alignment coincide with two
+characteristic regimes of the DM density profile: shallower and steeper than
+\rho r^{-2}. This alignment of the local velocity ellipsoids requires
+reinterpretation of features found in measurements based on the spherically
+averaged ratio of the radial-to-tangential velocity dispersions. In particular,
+we show that the velocity distribution in the central halo regions is highly
+anisotropic. For cluster-size haloes with mass 10^{14}-10^{15} h^-1 Msun, the
+velocity anisotropy along the major axis is nearly independent of radius and is
+equal to \beta=1-\sigma^2_{perp}/\sigma^2_{radial}=0.4, which is significantly
+larger than the previously estimated spherically averaged velocity anisotropy.
+The alignment of density and velocity anisotropies, and the radial trends may
+also have some implications for the mass modelling based on kinematical data of
+such objects as galaxy clusters or dwarf spheroidals, where the orbital
+anisotropy is a key element in an unbiased mass inference.",1303.2056v2
+2013-07-31,Lower Limits on the Anisotropy of the Extragalactic Gamma-Ray Background implied by the 2FGL and 1FHL Catalogs,"In principle, the angular anisotropy in the extragalactic gamma-ray
+background (EGRB) places severe constraints upon putative populations of
+unresolved gamma-ray point sources. Existing estimates of the EGRB anisotropy
+have been constructed by excising known point sources, e.g., taken from the
+First or 2 Year Fermi-LAT Source Catalog (1FGL or 2FGL, respectively) and
+statistically analyzing the residual gamma-ray sky maps. We perform an
+independent check of the EGRB anisotropy limits by comparing the values
+obtained from the 1FGL-masked sky maps to the signal implied by sources that
+lie below the 1FGL detection threshold in the more sensitive 2FGL and 1FHL
+(First Fermi-LAT catalog of >10 GeV sources). As such, our analysis provides an
+internal consistency check of implications for source counts and spectral index
+distributions of gamma-ray bright active galactic nuclei obtained from
+Fermi-LAT data. Based on this, we find evidence for substantially larger
+anisotropies than those previously reported at energies above 5 GeV, where BL
+Lac objects are likely to provide the bulk of their contribution to the EGRB.
+This uncertainty in the EGRB anisotropy cautions against using it as an
+independent constraint for the high-redshift gamma-ray universe. Moreover, this
+would suggest that contrary to previous claims, smooth extensions of the
+resolved point-source population may be able to simultaneously explain both the
+isotropic and anisotropic components of the EGRB.",1308.0015v2
+2014-01-06,Anisotropy expectations for ultra-high-energy cosmic rays with future high statistics experiments,"UHECRs have attracted a lot of attention due to their challengingly high
+energies and their potential value to constrain physical processes and
+astrophysical parameters in the most energetic sources of the universe. Current
+detectors have failed to detect significant anisotropies which had been
+expected to allow source identification. Some indications about the UHECR
+composition, which may become heavier at the highest energies, has even put
+into question the possibility that such a goal could be achieved soon.
+  We investigate the potential value of a new-generation detector, with 10
+times larger exposure, to overcome the current situation and make significant
+progress in the detection of anisotropies and thus in the study of UHECRs. We
+take as an example the expected performances of the JEM-EUSO, assuming a
+uniform full-sky coverage with a total exposure of 300,000 km2 sr yr.
+  We simulate realistic UHECR sky maps for a wide range of possible
+astrophysical scenarios allowed by the current constraints, taking into account
+the energy losses and photo-dissociation of the UHECRs, as well as their
+deflections by magnetic fields. These sky maps, built for the expected
+statistics of JEM-EUSO as well as for the current Auger statistics, as a
+reference, are analyzed from the point of view of their intrinsic anisotropies,
+using the two-point correlation function. A statistical study of the resulting
+anisotropies is performed for each astrophysical scenario, varying the UHECR
+source composition and spectrum as well as the source density.
+  We find that significant anisotropies are expected to be detected by a
+next-generation UHECR detector, for essentially all the astrophysical scenarios
+studied, and give precise, quantitative meaning to this statement. Our results
+show that a gain of one order of magnitude in exposure would make a significant
+difference compared to the existing detectors.",1401.1119v1
+2014-05-28,Scale and shape dependent non-Gaussianity in the presence of inflationary vector fields,"We consider cosmological inflationary models in which vector fields play some
+role in the generation of the primordial curvature perturbation $\zeta$. Such
+models are interesting because the involved vector fields naturally seed
+statistical anisotropy in the primordial fluctuations which could eventually
+leave a measurable imprint on the cosmic microwave background fluctuations. In
+this article, we estimate the scale and shape dependent effects on the
+non-Gaussianity (NG) parameters due to the scale dependent statistical
+anisotropy in the distribution of the fluctuations. For concreteness, we use a
+power spectrum (PS) of the fluctuations of the quadrupolar form:
+$P_\zeta(\vec{k})\equiv P_\zeta(k)[1+g_\zeta(k)(\hat{n} \cdot \hat{k})^2 ]$,
+where $g_{\zeta}(k)$ is the only quantity which parametrizes the level of
+statistical anisotropy and $\hat{n}$ is a unitary vector which points towards
+the preferred direction. Then, we evaluate the contribution of the running of
+$g_{\zeta}(k)$ on the NG parameters by means of the $\delta N$ formalism. We
+focus specifically on the details for the $f_{\rm NL}$ NG parameter, associated
+with the bispectrum $B_\zeta$, but the structure of higher order NG parameters
+is straightforward to generalize. Although the level of statistical anisotropy
+in the PS is severely constrained by recent observations, the importance of
+statistical anisotropy signals in higher order correlators remains to be
+determined, this being the main task that we address here. The precise
+measurement of the shape and scale dependence (or running) of statistical
+parameters such as the NG parameters and the statistical anisotropy level could
+provide relevant elements for model building and for the determination of the
+presence (or nonpresence) of inflationary vector fields and their role in the
+inflationary mechanism.",1405.7374v2
+2014-07-30,The expected anisotropy in solid inflation,"Solid inflation is an effective field theory of inflation in which isotropy
+and homogeneity are accomplished via a specific combination of anisotropic
+sources (three scalar fields that individually break isotropy). This results in
+specific observational signatures that are not found in standard models of
+inflation: a non-trivial angular dependence for the squeezed bispectrum, and a
+possibly long period of anisotropic inflation (to drive inflation, the ""solid""
+must be very insensitive to any deformation, and thus background anisotropies
+are very slowly erased). In this paper we compute the expected level of
+statistical anisotropy in the power spectrum of the curvature perturbations of
+this model. To do so, we account for the classical background values of the
+three scalar fields that are generated on large (superhorizon) scales during
+inflation via a random walk sum, as the perturbation modes leave the horizon.
+Such an anisotropy is unavoidably generated, even starting from perfectly
+isotropic classical initial conditions. The expected level of anisotropy is
+related to the duration of inflation and to the amplitude of the squeezed
+bispectrum. If this amplitude is close to its current observational limit (so
+that one of the most interesting predictions of the model can be observed in
+the near future), we find that a level of statistical anisotropy $\gtrsim 3\%$
+in the power spectrum is to be expected, if inflation lasted $\gtrsim 20-30$
+e-folds more than the final $50-60$ efolds required to generare the CMB modes.
+We also comment and point out various similarities between solid inflation and
+models of inflation where a suitable coupling of the inflaton to a vector
+kinetic term $F^{2}$ gives frozen and scale invariant vector perturbations on
+superhorizon scales.",1407.8053v1
+2015-09-21,Search for anisotropies in cosmic-ray positrons detected by the PAMELA experiment,"The PAMELA detector was launched on board of the Russian Resurs-DK1 satellite
+on June 15, 2006. Data collected during the first four years have been used to
+search for large-scale anisotropies in the arrival directions of cosmic-ray
+positrons. The PAMELA experiment allows for a full sky investigation, with
+sensitivity to global anisotropies in any angular window of the celestial
+sphere. Data samples of positrons in the rigidity range 10 GV $\leq$ R $\leq$
+200 GV were analyzed. This article discusses the method and the results of the
+search for possible local sources through analysis of anisotropy in positron
+data compared to the proton background. The resulting distributions of arrival
+directions are found to be isotropic. Starting from the angular power spectrum,
+a dipole anisotropy upper limit \delta = 0.166 at 95% C.L. is determined.
+Additional search is carried out around the Sun. No evidence of an excess
+correlated with that direction was found.",1509.06249v2
+2016-06-14,Direct probe of anisotropy in atom-molecule collisions via quantum scattering resonances,"Anisotropy is a fundamental property of particle interactions. It occupies a
+central role in cold and ultra-cold molecular processes, where long range
+forces have been found to significantly depend on orientation in ultra-cold
+polar molecule collisions. Recent experiments have demonstrated the emergence
+of quantum phenomena such as scattering resonances in the cold collisions
+regime due to quantization of the intermolecular degrees of freedom. Although
+these states have been shown to be sensitive to interaction details, the effect
+of anisotropy on quantum resonances has eluded experimental observation so far.
+Here, we directly measure the anisotropy in atom-molecule interactions via
+quantum resonances by changing the quantum state of the internal molecular
+rotor. We observe that a quantum scattering resonance at a collision energy of
+$k_B$ x 270 mK appears in the Penning ionization of molecular hydrogen with
+metastable helium only if the molecule is rotationally excited. We use state of
+the art ab initio and multichannel quantum molecular dynamics calculations to
+show that the anisotropy contributes to the effective interaction only for
+$H_2$ molecules in the first excited rotational state, whereas rotationally
+ground state $H_2$ interacts purely isotropically with metastable helium.
+Control over the quantum state of the internal molecular rotation allows us to
+switch the anisotropy on or off and thus disentangle the isotropic and
+anisotropic parts of the interaction. These quantum phenomena provide a
+challenging benchmark for even the most advanced theoretical descriptions,
+highlighting the advantage of using cold collisions to advance the microscopic
+understanding of particle interactions.",1606.04384v1
+2016-10-13,When the Jeans don't fit: How stellar feedback drives stellar kinematics and complicates dynamical modeling in low-mass galaxies,"In low-mass galaxies, stellar feedback can drive gas outflows that generate
+non-equilibrium fluctuations in the gravitational potential. Using cosmological
+zoom-in baryonic simulations from the Feedback in Realistic Environments (FIRE)
+project, we investigate how these fluctuations affect stellar kinematics and
+the reliability of Jeans dynamical modeling in low-mass galaxies. We find that
+stellar velocity dispersion and anisotropy profiles fluctuate significantly
+over the course of galaxies' starburst cycles. We therefore predict an
+observable correlation between star formation rate and stellar kinematics:
+dwarf galaxies with higher recent star formation rates should have systemically
+higher stellar velocity dispersions. This prediction provides an observational
+test of the role of stellar feedback in regulating both stellar and dark-matter
+densities in dwarf galaxies. We find that Jeans modeling, which treats galaxies
+as virialized systems in dynamical equilibrium, overestimates a galaxy's
+dynamical mass during periods of post-starburst gas outflow and underestimates
+it during periods of net inflow. Short-timescale potential fluctuations lead to
+typical errors of $\sim 20\%$ in dynamical mass estimates, even if full
+3-dimensional stellar kinematics -- including the orbital anisotropy -- are
+known exactly. When orbital anisotropy is $\textit{not}$ known a priori,
+typical mass errors arising from non-equilibrium fluctuations in the potential
+are larger than those arising from the mass-anisotropy degeneracy. However,
+Jeans modeling alone $\textit{cannot}$ reliably constrain the orbital
+anisotropy, and problematically, it often favors anisotropy models that do not
+reflect the true profile. If galaxies completely lose their gas and cease
+forming stars, fluctuations in the potential subside, and Jeans modeling
+becomes much more reliable.",1610.04232v2
+2016-11-27,Features of collisionless turbulence in the intracluster medium from simulated Faraday rotation maps II: the effects of instabilities feedback,"Statistical analysis of Faraday Rotation Measure (RM) maps of the
+intracluster medium (ICM) of galaxy clusters provides a unique tool to evaluate
+some spatial features of the magnetic fields there. Its combination with
+numerical simulations of magnetohydrodynamic (MHD) turbulence allows the
+diagnosis of the ICM turbulence. Being the ICM plasma weakly collisional, the
+thermal velocity distribution of the particles naturally develops anisotropies
+as a consequence of the large scale motions and the conservation of the
+magnetic moment of the charged particles. A previous study (Paper I) analyzed
+the impact of large scale thermal anisotropy on the statistics of RM maps
+synthesized from simulations of turbulence; these simulations employed a
+collisionless MHD model which considered a tensor pressure with uniform
+anisotropy. In the present work, we extend that analysis to a collisionless MHD
+model in which the thermal anisotropy develops according to the conservation of
+the magnetic moment of the thermal particles. We also consider the effect of
+anisotropy relaxation caused by the micro-scale mirror and firehose
+instabilities. We show that if the relaxation rate is fast enough to keep the
+anisotropy limited by the threshold values of the instabilities, the dispersion
+and power spectrum of the RM maps are indistinguishable from those obtained
+from collisional MHD. Otherwise, there is a reduction in the dispersion and
+steepening of the power spectrum of the RM maps (compared to the collisional
+case). Considering the first scenario, the use of collisional MHD simulations
+for modeling the RM statistics in the ICM becomes better justified.",1611.10183v1
+2017-01-06,Magnetization in narrow ribbons: curvature effects,"A ribbon is a surface swept out by a line segment turning as it moves along a
+central curve. For narrow magnetic ribbons, for which the length of the line
+segment is much less than the length of the curve, the anisotropy induced by
+the magnetostatic interaction is biaxial, with hard axis normal to the ribbon
+and easy axis along the central curve. The micromagnetic energy of a narrow
+ribbon reduces to that of a one-dimensional ferromagnetic wire, but with
+curvature, torsion and local anisotropy modified by the rate of turning. These
+general results are applied to two examples, namely a helicoid ribbon, for
+which the central curve is a straight line, and a M\""obius ribbon, for which
+the central curve is a circle about which the line segment executes a
+$180^\circ$ twist. In both examples, for large positive tangential anisotropy,
+the ground state magnetization lies tangent to the central curve. As the
+tangential anisotropy is decreased, the ground state magnetization undergoes a
+transition, acquiring an in-surface component perpendicular to the central
+curve. For the helicoid ribbon, the transition occurs at vanishing anisotropy,
+below which the ground state is uniformly perpendicular to the central curve.
+The transition for the M\""obius ribbon is more subtle; it occurs at a positive
+critical value of the anisotropy, below which the ground state is nonuniform.
+For the helicoid ribbon, the dispersion law for spin wave excitations about the
+tangential state is found to exhibit an asymmetry determined by the geometric
+and magnetic chiralities.",1701.01691v1
+2017-06-16,Anisotropic spin-density distribution and magnetic anisotropy of strained La$_{1-x}$Sr$_x$MnO$_3$ thin films: Angle-dependent x-ray magnetic circular dichroism,"Magnetic anisotropies of ferromagnetic thin films are induced by epitaxial
+strain from the substrate via strain-induced anisotropy in the orbital magnetic
+moment and that in the spatial distribution of spin-polarized electrons.
+However, the preferential orbital occupation in ferromagnetic metallic
+La$_{1-x}$Sr$_x$MnO$_3$ (LSMO) thin films studied by x-ray linear dichroism
+(XLD) has always been found out-of-plane for both tensile and compressive
+epitaxial strain and hence irrespective of the magnetic anisotropy. In order to
+resolve this mystery, we directly probed the preferential orbital occupation of
+spin-polarized electrons in LSMO thin films under strain by angle-dependent
+x-ray magnetic circular dichroism (XMCD). Anisotropy of the spin-density
+distribution was found to be in-plane for the tensile strain and out-of-plane
+for the compressive strain, consistent with the observed magnetic anisotropy.
+The ubiquitous out-of-plane preferential orbital occupation seen by XLD is
+attributed to the occupation of both spin-up and spin-down out-of-plane
+orbitals in the surface magnetic dead layer.",1706.05183v5
+2017-09-15,Pressure-anisotropy-induced nonlinearities in the kinetic magnetorotational instability,"In collisionless and weakly collisional plasmas, such as hot accretion flows
+onto compact objects, the magnetorotational instability (MRI) can differ
+significantly from the standard (collisional) MRI. In particular, pressure
+anisotropy with respect to the local magnetic-field direction can both change
+the linear MRI dispersion relation and cause nonlinear modifications to the
+mode structure and growth rate, even when the field and flow perturbations are
+small. This work studies these pressure-anisotropy-induced nonlinearities in
+the weakly nonlinear, high-ion-beta regime, before the MRI saturates into
+strong turbulence. Our goal is to better understand how the saturation of the
+MRI in a low collisionality plasma might differ from that in the collisional
+regime. We focus on two key effects: (i) the direct impact of self-induced
+pressure-anisotropy nonlinearities on the evolution of an MRI mode, and (ii)
+the influence of pressure anisotropy on the ""parasitic instabilities"" that are
+suspected to cause the mode to break up into turbulence. Our main conclusions
+are: (i) The mirror instability regulates the pressure anisotropy in such a way
+that the linear MRI in a collisionless plasma is an approximate nonlinear
+solution once the mode amplitude becomes larger than the background field (just
+as in MHD). This implies that differences between the collisionless and
+collisional MRI become unimportant at large amplitudes. (ii) The break up of
+large amplitude MRI modes into turbulence via parasitic instabilities is
+similar in collisionless and collisional plasmas. Together, these conclusions
+suggest that the route to magnetorotational turbulence in a collisionless
+plasma may well be similar to that in a collisional plasma, as suggested by
+recent kinetic simulations. As a supplement to these findings, we offer
+guidance for the design of future kinetic simulations of magnetorotational
+turbulence.",1709.05428v2
+2018-05-11,Anisotropy of the Milky Way's stellar halo using K giants from LAMOST and $Gaia$,"The anisotropy parameter $\beta$ characterizes the extent to which orbits in
+stellar systems are predominantly radial or tangential, and is likely to
+constrain, for the stellar halo of the Milky Way, scenarios for its formation
+and evolution. We have measured the anisotropy $\beta$ as a function of
+Galactocentric radius from $5-100$ kpc for over 8600 metal poor ([Fe/H]
+$<-1.3$) halo K giants from the LAMOST catalog with line-of-sight velocities
+and distances, matched to proper motions from the second $Gaia$ data release.
+We construct full 6-D positions and velocities for the K giants to directly
+measure the 3 components of the velocity dispersion $(\sigma_r, \sigma_\theta,
+\sigma_\phi)$ (in spherical coordinates). We find that the orbits in the halo
+are radial over our full Galactocentric distance range reaching over 100 kpc.
+The anisotropy remains remarkably unchanged with Galactocentric radius from
+approximately 5 to 25 kpc, with an amplitude that depends on the metallicity of
+the stars, dropping from $\beta \approx 0.9$ for $-1.8 \leq$ [Fe/H] $< -1.3$
+(for the bulk of the stars) to $\beta \approx 0.6$ for the lowest metallicities
+([Fe/H] $< -1.8$). Considering our sample as a whole, $\beta\approx0.8$ and,
+beyond 25 kpc, the orbits gradually become less radial and anisotropy decreases
+to $\beta<0.3$ past 100 kpc. Within 8 kpc, $\beta<0.8$. The measurement of
+anisotropy is affected by substructure and streams, particularly beyond a
+Galactocentric distance of approximately 25 kpc, where the Sagittarius stream
+is prominent in the data. These results are complimentary to recent analysis of
+simulations by Loebman et al. and of SDSS/$Gaia$ DR1 data by Belokurov et al.",1805.04503v2
+2018-07-25,A mass-velocity anisotropy relation in galactic stellar disks,"The ellipsoid of stellar random motions is a fundamental ingredient of galaxy
+dynamics. Yet it has long been difficult to constrain this component in disks
+others than the Milky Way. This article presents the modeling of the
+azimuthal-to-radial axis ratio of the velocity ellipsoid of galactic disks from
+stellar dispersion maps using integral field spectroscopy data of the CALIFA
+survey. The measured azimuthal anisotropy is shown to be not strongly dependent
+on the assumed vertical-to-radial dispersion ratio of the ellipsoid. The
+anisotropy distribution shows a large diversity in the orbital structure of
+disk galaxies from tangential to radial stellar orbits. Globally, the orbits
+are isotropic in inner disk regions and become more radial as a function of
+radius, although this picture tends to depend on galaxy morphology and
+luminosity. The Milky Way orbital anisotropy profile measured from the Second
+Gaia Data Release is consistent with those of CALIFA galaxies. A new
+correlation is evidenced, linking the absolute magnitude or stellar mass of the
+disks to the azimuthal anisotropy. More luminous disks have more radial orbits
+and less luminous disks have isotropic and somewhat tangential orbits. This
+correlation is consistent with the picture in galaxy evolution in which orbits
+become more radial as the mass grows and is redistributed as a function of
+time. With the help of circular velocity curves, it is also shown that the
+epicycle theory fails to reproduce the diversity of the azimuthal anisotropy of
+stellar random motions, as it predicts only nearly radial orbits in the
+presence of flat curves. The origin of this conflict is yet to be identified.
+It also questions the validity of the vertical-to-radial axis ratio of the
+velocity ellipsoid derived by many studies in the framework of the epicyclic
+approximation.",1807.09833v2
+2018-08-15,Large magneto-optical effects and magnetic anisotropy energy in two-dimensional Cr$_2$Ge$_2$Te$_6$,"By performing systematic $ab$ $initio$ density functional calculations, here
+we study two relativity-induced properties of atomically thin ferromagnetic
+(FM) Cr$_2$Ge$_2$Te$_6$ films [monolayer (ML), bilayer (BL) and trilayer (TL)
+as well as bulk], namely, magnetic anisotropy energy (MAE) and magneto-optical
+(MO) effects. Competing contributions of both magneto-crystalline anisotropy
+energy (C-MAE) and magnetic dipolar anisotropy energy (D-MAE) to the MAE, are
+computed. Calculated MAEs of these materials are large, being in the order of
+$\sim$0.1 meV/Cr. Interestingly, we find that the out-of-plane magnetic
+anisotropy is preferred in all the systems except the ML where an in-plane
+magnetization is favored because here the D-MAE is larger than the C-MAE.
+Crucially, this explains why long-range FM order was observed in all the
+few-layer Cr$_2$Ge$_2$Te$_6$ except the ML because the out-of-plane magnetic
+anisotropy would open a spin-wave gap and thus suppress magnetic fluctuations
+so that long-range FM order could be stabilized at finite temperature. In the
+visible frequency range, large Kerr rotations up to $\sim$1.0 deg in these
+materials are predicted and they are comparable to that observed in famous MO
+materials such as PtMnSb and Y$_3$Fe$_5$O$_{12}$. Moreover, they are $\sim$100
+times larger than that of 3$d$ transition metal MLs deposited on Au surfaces.
+Faraday rotation angles in these 2D materials are also large, being up to
+$\sim$120 deg/$\mu$m, and are thus comparable to the best-known MO
+semiconductor Bi$_3$Fe$_5$O$_{12}$. These findings thus suggest that with large
+MAE and MO effects, atomically thin Cr$_2$Ge$_2$Te$_6$ films would have
+potential applications in novel magnetic, MO and spintronic nanodevices.",1808.05086v1
+2019-12-09,Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with First Parker Solar Probe Observations,"We report proton temperature anisotropy variations in the inner heliosphere
+with Parker Solar Probe (PSP) observations. Using a linear fitting method, we
+derive proton temperature anisotropy with temperatures measured by the Solar
+Probe Cup (SPC) from the SWEAP instrument suite and magnetic field observations
+from the FIELDS instrument suite. The observed radial dependence of temperature
+variations in the fast solar wind implies stronger perpendicular heating and
+parallel cooling than previous results from Helios measurements made at larger
+radial distances. The anti-correlation between proton temperature anisotropy
+and parallel plasma beta is retained in fast solar wind. However, the
+temperature anisotropies of the slow solar wind seem to be well constrained by
+the mirror and parallel firehose instabilities. The perpendicular heating of
+the slow solar wind inside 0.24 AU may contribute to its same trend up against
+mirror instability thresholds as fast solar wind. These results suggest that we
+may see stronger anisotropy heating than expected in inner heliosphere.",1912.03871v2
+2020-01-07,Full-sky searches for anisotropies in UHECR arrival directions with the Pierre Auger Observatory and the Telescope Array,"The arrival directions of ultra-high-energy cosmic rays appear to be
+approximately isotropically distributed over the whole sky, but the
+last-generation UHECR detector arrays, the Pierre Auger Observatory (Auger) and
+the Telescope Array (TA), have detected thousands of events, allowing us to
+study small deviations from isotropy. So far, Auger has detected a large-scale
+anisotropy consistent with a $\sim 6.5\%$ dipole moment in the distribution of
+cosmic rays with $E > 8$~EeV, and both collaborations have reported indications
+for smaller-scale anisotropies at higher energies. On the other hand, neither
+array has full-sky coverage, the Auger field of view being limited to
+declinations $\delta < +45^\circ$ and the TA one to $\delta > -16^\circ$.
+Searches for anisotropies with full-sky coverage thus require combining data
+from both arrays. A working group with members from both collaborations has
+been established for this task. Since even a minor systematic error in the
+energy determinations at either of the arrays could result in a sizeable
+spurious anisotropy along the north--south axis, we devised a method to
+cross-calibrate the energy scales of the two experiments with respect to each
+other by using events in a declination band within the intersection of their
+fields of view. In this contribution, we report on both updates on blind
+searches for anisotropies and the first full-sky studies of flux models based
+on possible local extragalactic sources.",2001.01864v1
+2020-04-02,Introducing Anisotropic Minkowski Functionals and Quantitative Anisotropy Measures for Local Structure Analysis in Biomedical Imaging,"The ability of Minkowski Functionals to characterize local structure in
+different biological tissue types has been demonstrated in a variety of medical
+image processing tasks. We introduce anisotropic Minkowski Functionals (AMFs)
+as a novel variant that captures the inherent anisotropy of the underlying
+gray-level structures. To quantify the anisotropy characterized by our
+approach, we further introduce a method to compute a quantitative measure
+motivated by a technique utilized in MR diffusion tensor imaging, namely
+fractional anisotropy. We showcase the applicability of our method in the
+research context of characterizing the local structure properties of trabecular
+bone micro-architecture in the proximal femur as visualized on multi-detector
+CT. To this end, AMFs were computed locally for each pixel of ROIs extracted
+from the head, neck and trochanter regions. Fractional anisotropy was then used
+to quantify the local anisotropy of the trabecular structures found in these
+ROIs and to compare its distribution in different anatomical regions. Our
+results suggest a significantly greater concentration of anisotropic trabecular
+structures in the head and neck regions when compared to the trochanter region
+(p < 10-4). We also evaluated the ability of such AMFs to predict bone strength
+in the femoral head of proximal femur specimens obtained from 50 donors. Our
+results suggest that such AMFs, when used in conjunction with multi-regression
+models, can outperform more conventional features such as BMD in predicting
+failure load. We conclude that such anisotropic Minkowski Functionals can
+capture valuable information regarding directional attributes of local
+structure, which may be useful in a wide scope of biomedical imaging
+applications.",2004.01185v1
+2020-06-23,Unlocking the synergy between CMB spectral distortions and anisotropies,"Measurements of the cosmic microwave background (CMB) spectral distortions
+(SDs) will open a new window on the very early universe, providing new
+information complementary to that gathered from CMB temperature and
+polarization anisotropies. In this paper, we study their synergy as a function
+of the characteristics of the considered experiments. In particular, we examine
+a wide range of sensitivities for possible SD measurements, spanning from FIRAS
+up to noise levels 1000 times better than PIXIE, and study their constraining
+power when combined with current or future CMB anisotropy experiments such as
+Planck or LiteBIRD plus CMB-S4. We consider a number of different cosmological
+models such as the $\Lambda$CDM, as well as its extensions with the running of
+the scalar spectral index, the decay or the annihilation of dark matter (DM)
+particles. While upcoming CMB anisotropy experiments will be able to decrease
+the uncertainties on inflationary parameters such as $A_s$ and $n_s$ by about a
+factor 2 in the $\Lambda$CDM case, we find that an SD experiment 100 times more
+sensitive than PIXIE (comparable to the proposed Super-PIXIE satellite) could
+potentially further contribute to constrain these parameters. This is even more
+significant in the case of the running of the scalar spectral index.
+Furthermore, as expected, constraints on DM particles decaying at redshifts
+probed by SDs will improve by orders of magnitude even with an experiment 10
+times worse than PIXIE as compared to CMB anisotropies or Big Bang
+Nucleosynthesis bounds. On the contrary, DM annihilation constraints will not
+significantly improve over CMB anisotropy measurements. Finally, we forecast
+the constraints obtainable with sensitivities achievable either from the ground
+or from a balloon.",2006.12886v2
+2021-04-09,"Joint Gas and Stellar Dynamical Models of WLM: An isolated dwarf galaxy within a cored, prolate DM halo","We present multi-tracer dynamical models of the low mass ($M_{*} \sim
+10^{7}$), isolated dwarf irregular galaxy WLM in order to simultaneously
+constrain the inner slope of the dark matter (DM) halo density profile
+($\gamma$) and flattening ($q_\mathrm{DM}$), and the stellar orbital anisotropy
+($\beta_{z}, \beta_{r}$). For the first time, we show how jointly constraining
+the mass distribution from the HI gas rotation curve and solving the Jeans'
+equations with discrete stellar kinematics leads to a factor of $\sim2$
+reduction in the uncertainties on $\gamma$. The mass-anisotropy degeneracy is
+also partially broken, leading to reductions on uncertainty by $\sim 30\%$ on
+$M_\mathrm{vir}$ (and $\sim 70\%$ at the half-light radius) and $\sim 25\%$ on
+anisotropy. Our inferred value of $\gamma = 0.3 \pm 0.1$ is robust to the halo
+geometry, and in excellent agreement with predictions of stellar feedback
+driven DM core creation. The derived prolate geometry of the DM halo with
+$q_\mathrm{DM} = 2 \pm 1$ is consistent with $\Lambda$CDM simulations of dwarf
+galaxy halos. While self-interacting DM (SIDM) models with $\sigma/m_{X} \sim
+0.6$ can reproduce this cored DM profile, the interaction events may
+sphericalise the halo. The simultaneously cored and prolate DM halo may
+therefore present a challenge for SIDM. Finally we find that the radial profile
+of stellar anisotropy in WLM ($\beta_{r}$) follows a nearly identical trend of
+increasing tangential anisotropy to the classical dSphs, Fornax and Sculptor.
+Given WLM's orbital history, this result may call into question whether such
+anisotropy is a consequence of tidal stripping in only one pericentric passage
+or if it instead is a feature of the largely self-similar formation and
+evolutionary pathways for some dwarf galaxies.",2104.04273v1
+2021-08-31,Strain-controlled Domain Wall injection into nanowires for sensor applications,"We investigate experimentally the effects of externally applied strain on the
+injection of 180$^\circ$ domain walls (DW) from a nucleation pad into magnetic
+nanowires, as typically used for DW-based sensors. In our study the strain,
+generated by substrate bending, induces in the material a uniaxial anisotropy
+due to magnetoelastic coupling. To compare the strain effects,
+$Co_{40}Fe_{40}B_{20}$, $Ni$ and $Ni_{82}Fe_{18}$ samples with in-plane
+magnetization and different magnetoelastic coupling are deposited. In these
+samples, we measure the magnetic field required for the injection of a DW, by
+imaging differential contrast in a magneto-optical Kerr microscope. We find
+that strain increases the DW injection field, however, the switching mechanism
+depends strongly on the direction of the strain with respect to the wire axis.
+We observe that low magnetic anisotropy facilitates the creation of a domain
+wall at the junction between the pad and the wire, whereas a strain-induced
+magnetic easy axis significantly increases the coercive field of the nucleation
+pad. Additionally, we find that the effects of mechanical strain can be
+counteracted by a magnetic uniaxial anisotropy perpendicular to the
+strain-induced easy axis. In $Co_{40}Fe_{40}B_{20}$, we show that this
+anisotropy can be induced by annealing in a magnetic field. We perform
+micromagnetic simulations to support the interpretation of our experimental
+findings. Our simulations show that the above described observations can be
+explained by the effective anisotropy in the device. The anisotropy influences
+the switching mechanism in the nucleation pad as well as the pinning of the DW
+at the wire entrance. As the DW injection is a key operation for sensor
+performances, the observations show that strain is imposing a lower limit for
+the sensor field operating window.",2108.13881v1
+2021-10-27,Leverage on small-scale primordial non-Gaussianity through cross-correlations between CMB $E$-mode and $μ$-distortion anisotropies,"Multi-field inflation models and non-Bunch-Davies vacuum initial conditions
+both predict sizeable non-Gaussian primordial perturbations and anisotropic
+$\mu$-type spectral distortions of the cosmic microwave background (CMB)
+blackbody. While CMB anisotropies allow us to probe non-Gaussianity at
+wavenumbers $k\simeq 0.05\,{\rm Mpc^{-1}}$, $\mu$-distortion anisotropies are
+related to non-Gaussianity of primordial perturbation modes with much larger
+wavenumbers, $k\simeq 740\,{\rm Mpc^{-1}}$. Through cross-correlations between
+CMB and $\mu$-distortion anisotropies, one can therefore shed light on the
+aforementioned inflation models. We investigate the ability of a future CMB
+satellite imager like LiteBIRD to measure $\mu T$ and $\mu E$ cross-power
+spectra between anisotropic $\mu$-distortions and CMB temperature and $E$-mode
+polarization anisotropies in the presence of foregrounds, and derive LiteBIRD
+forecasts on ${f_{\rm NL}^\mu(k\simeq 740\,{\rm Mpc^{-1}})}$. We show that $\mu
+E$ cross-correlations with CMB polarization provide more constraining power on
+$f_{\rm NL}^\mu$ than $\mu T$ cross-correlations in the presence of
+foregrounds, and the joint combination of $\mu T$ and $\mu E$ observables adds
+further leverage to the detection of small-scale primordial non-Gaussianity. We
+find that LiteBIRD would detect ${f_{\rm NL}^\mu}=4500$ at $5\sigma$
+significance after foreground removal, and achieve a minimum error of
+${\sigma(f_{\rm NL}^\mu=0) \simeq 800}$ at 68\% CL by combining CMB temperature
+and polarization. Due to the huge dynamic range of wavenumbers between CMB and
+$\mu$-distortion anisotropies, such large $f^\mu_{\rm NL}$ values would still
+be consistent with current CMB constraints in the case of very mild
+scale-dependence of primordial non-Gaussianity. Anisotropic spectral
+distortions thus provide a new path, complementary to CMB $B$-modes, to probe
+inflation with LiteBIRD.",2110.14664v2
+2022-01-19,On the Energy Dependence of Galactic Cosmic Ray Anisotropies in the Very Local Interstellar Medium,"We report on the energy dependence of galactic cosmic rays (GCRs) in the very
+local interstellar medium (VLISM) as measured by the Low Energy Charged
+Particle (LECP) instrument on the Voyager 1 (V1) spacecraft. The LECP
+instrument includes a dual-ended solid state detector particle telescope
+mechanically scanning through 360 deg across eight equally-spaced angular
+sectors. As reported previously, LECP measurements showed a dramatic increase
+in GCR intensities for all sectors of the >=211 MeV count rate (CH31) at the V1
+heliopause (HP) crossing in 2012, however, since then the count rate data have
+demonstrated systematic episodes of intensity decrease for particles around
+90{\deg} pitch angle. To shed light on the energy dependence of these GCR
+anisotropies over a wide range of energies, we use V1 LECP count rate and pulse
+height analyzer (PHA) data from >=211 MeV channel together with lower energy
+LECP channels. Our analysis shows that while GCR anisotropies are present over
+a wide range of energies, there is a decreasing trend in the amplitude of
+second-order anisotropy with increasing energy during anisotropy episodes. A
+stronger pitch-angle scattering at the higher velocities is argued as a
+potential cause for this energy dependence. A possible cause for this velocity
+dependence arising from weak rigidity dependence of the scattering mean free
+path and resulting velocity-dominated scattering rate is discussed. This
+interpretation is consistent with a recently reported lack of corresponding GCR
+electron anisotropies.",2201.07844v1
+2022-01-20,Event-by-event jet anisotropy and hard-soft tomography of the quark-gluon plasma,"Suppression of jet spectra or jet quenching in high-energy heavy-ion
+collisions is caused by jet energy loss in the dense medium. The azimuthal
+anisotropy of jet energy loss in non-central heavy-ion collisions can lead to
+jet anisotropy which in turn can provide insight into the path-length
+dependence of jet quenching. This is investigated within the Linear Boltzmann
+Transport (LBT) model which simulates both elastic scattering and
+medium-induced gluon radiation based on perturbative QCD for jet shower and
+medium recoil partons as well as radiated gluons as they propagate through the
+quark-gluon plasma (QGP). The dynamical evolution of the QGP in each event of
+heavy-ion collisions is provided by the (3+1)D CLVisc hydrodynamic model with
+fully fluctuating initial conditions. This framework has been shown to describe
+the suppression of single inclusive jet spectra well. We calculate in this
+study the elliptic ($v_{2}^{\rm jet}$) and triangular ($v_{3}^{\rm jet}$)
+anisotropy coefficients of the single inclusive jet spectra in Pb+Pb collisions
+at the LHC energies. We investigate the colliding energy, centrality, jet
+transverse momentum dependence of the jet anisotropy, as well as their
+event-by-event correlation with the flow coefficients of the soft bulk hadrons.
+An approximate linear correlation between jet and bulk $v_2$ is found. Effect
+of the bulk $v_n$ fluctuation on $v_n^{\rm jet}$ is found negligible. The
+jet-induced medium excitation, which is influenced by radial flow, is shown to
+enhance $v_{2}^{\rm jet}$ and the enhancement increases with the jet cone size.
+The jet elliptic anisotropy $v_{2}^{\rm jet}$ is also found to be slightly
+enhanced by the shear viscosity of the bulk medium in comparison to the LBT
+results when jets propagate through an ideal hydrodynamic QGP medium.",2201.08408v1
+2022-02-17,"Doping control of magnetic anisotropy for stable antiskyrmion formation in schreibersite (Fe,Ni)$_3$P with $S_4$ symmetry","Magnetic skyrmions, vortex-like topological spin textures, have attracted
+much interest in a wide range of research fields from fundamental physics to
+spintronics applications. Recently, growing attention has also been paid to
+antiskyrmions emerging in opposite topological charge in non-centrosymmetric
+magnets with $D_{2\mathrm{d}}$ or $S_4$ symmetry. In these magnets, complex
+interplay among anisotropic Dzyaloshinskii-Moriya interaction, uniaxial
+magnetic anisotropy, and magnetic dipolar interactions generates a variety of
+magnetic structures. However, the relation between the stability of
+antiskyrmions and these magnetic interactions remains to be elucidated. In this
+work, we control the uniaxial magnetic anisotropy of schreibersite (Fe,Ni)$_3$P
+with $S_4$ symmetry by doping and investigate its impact on the stability of
+antiskyrmions. Our magnetometry study, supported by ferromagnetic resonance
+spectroscopy, shows that the variation of the Ni content and slight doping with
+4$d$ transition metals considerably change the magnetic anisotropy. In
+particular, doping with Pd induces easy-axis anisotropy, giving rise to
+formation of antiskyrmions, while a temperature-induced spin reorientation is
+observed in a Rh-doped compound. In combination with Lorentz transmission
+electron microscopy and micromagnetic simulations, we quantitatively analyze
+the stability of antiskyrmion as functions of uniaxial anisotropy and
+demagnetization energy, and demonstrate that subtle balance between them is
+necessary to stabilize the antiskyrmions.",2202.08483v1
+2023-02-20,Pressure anisotropy and viscous heating in weakly collisional plasma turbulence,"Pressure anisotropy can strongly influence the dynamics of weakly
+collisional, high-beta plasmas, but its effects are missed by standard
+magnetohydrodynamics (MHD). Small changes to the magnetic-field strength
+generate large pressure-anisotropy forces, heating the plasma, driving
+instabilities, and rearranging flows, even on scales far above the particles'
+gyroscales where kinetic effects are traditionally considered important. Here,
+we study the influence of pressure anisotropy on turbulent plasmas threaded by
+a mean magnetic field (Alfv\'enic turbulence). Extending previous results that
+were concerned with Braginskii MHD, we consider a wide range of regimes and
+parameters using a simplified fluid model based on drift kinetics with heat
+fluxes calculated using a Landau-fluid closure. We show that viscous
+(pressure-anisotropy) heating dissipates between a quarter and half of the
+turbulent cascade power injected at large scales; this does not depend strongly
+on either plasma beta or the ion-to-electron temperature ratio. This will in
+turn influence the plasma's thermodynamics by regulating energy partition
+between different dissipation channels (e.g., electron and ion heat). Due to
+the pressure anisotropy's rapid dynamical feedback onto the flows that create
+it -- an effect we term `magneto-immutability' -- the viscous heating is
+confined to a narrow range of scales near the forcing scale, supporting a
+nearly conservative, MHD-like inertial-range cascade, via which the rest of the
+energy is transferred to small scales. Despite the simplified model, our
+results -- including the viscous heating rate, distributions, and turbulent
+spectra -- compare favourably to recent hybrid-kinetic simulations. This is
+promising for the more general use of extended-fluid (or even MHD) approaches
+to model weakly collisional plasmas such as the intracluster medium, hot
+accretion flows, and the solar wind.",2303.00468v2
+2023-09-13,Beyond the Background: Gravitational Wave Anisotropy and Continuous Waves from Supermassive Black Hole Binaries,"Pulsar timing arrays have found evidence for a low-frequency gravitational
+wave background (GWB). Assuming the GWB is produced by supermassive black hole
+binaries (SMBHBs), the next gravitational wave (GW) signals astronomers
+anticipate are Continuous Waves (CWs) from single SMBHBs and their associated
+GWB anisotropy. The prospects for detecting CWs and anisotropy are highly
+dependent on the astrophysics of SMBHB populations. Thus, information from
+single sources can break degeneracies in astrophysical models and place much
+more stringent constraints than the GWB alone. We simulate and evolve SMBHB
+populations, model their GWs, and calculate their anisotropy and detectability.
+We investigate how varying components of our semi-analytic model, including the
+galaxy stellar mass function, the SMBH--host galaxy relation
+($M_\mathrm{BH}$--$M_\mathrm{bulge}$), and the binary evolution prescription
+impact the expected detections. The CW occurrence rate is greatest for few
+total binaries, high SMBHB masses, large scatter in
+$M_\mathrm{BH}$--$M_\mathrm{bulge}$, and long hardening times. The occurrence
+rate depends most on the binary evolution parameters, implying that CWs offer a
+novel avenue to probe binary evolution. The most detectable CW sources are in
+the lowest frequency bin for a 16.03-year PTA, have masses from
+$\sim\!\!10^9-10^{10}\mathrm{M}_\odot$, and are $\sim\!\!1$ Gpc away. The level
+of anisotropy increases with frequency, with the angular power spectrum over
+multipole modes $\ell$ varying in low-frequency $C_{\ell>0}/C_0$ from
+$\sim\!\!5\times 10^{-3}$ to $\sim\!\!2\times10^{-1}$, depending on the model;
+typical values are near current upper limits. Observing this anisotropy would
+support SMBHB models for the GWB over cosmological models, which tend to be
+isotropic.",2309.07227v2
+2024-02-09,Crossover From Individual to Collective Magnetism in Dense Nanoparticle Systems: Local Anisotropy Versus Dipolar Interactions,"Dense systems of magnetic nanoparticles may exhibit dipolar collective
+behavior. However, two fundamental questions remain unsolved: i) whether the
+transition temperature may be affected by the particle anisotropy or it is
+essentially determined by the intensity of the interparticle dipolar
+interactions, and ii) what is the minimum ratio of dipole-dipole interaction
+($E_\text{dd}$) to nanoparticle anisotropy ($K_{\text{ef}}V$, anisotropy
+$\times$ volume) energies necessary to crossover from individual to collective
+behavior. A series of particle assemblies with similarly intense dipolar
+interactions but widely varying anisotropy is studied. The $K_\text{ef}$ is
+tuned through different degrees of cobalt-doping in maghemite nanoparticles,
+resulting in a variation of nearly an order of magnitude. All the bare particle
+compacts display collective behavior, except the one made with the highest
+anisotropy particles, which presents ``marginal'' features. Thus, a threshold
+of $K_{\text{ef}} V/E_{\text{dd}} \approx 130$ to suppress collective behavior
+is derived, in good agreement with Monte Carlo simulations. This translates
+into a crossover value of $\approx 1.7$ for the easily accessible parameter
+$T_\text{MAX}$(interacting)$/T_\text{MAX}$(non-interacting) (ratio of the peak
+temperatures of the zero-field-cooled magnetization curves of interacting and
+dilute particle systems), which is successfully tested against the literature
+to predict the individual-like$/$collective behavior of any given interacting
+particle assembly comprising relatively uniform particles.",2402.06583v1
+2024-03-29,Influence of pressure anisotropy and non-metricity parameter on mass-radius relation and stability of millisecond pulsar in $f(Q)$ gravity,"In this study we explore the astrophysical implications of pressure
+anisotropy on the physical characteristics of millisecond pulsars within the
+framework of $f(Q)$ gravity. Starting off with the field equations for
+anisotropic matter distributions, we adopt the physically salient
+Durgapal-Fuloria ansatz together with a well-motivated anisotropic factor for
+the interior matter distribution. This leads to a nonlinear second order
+differential equation which is integrated to give the complete gravitational
+and thermodynamical properties of the stellar object. The resulting model is
+subjected to rigorous tests to ensure that it qualifies as a physically viable
+compact object within the $f(Q)$-gravity framework. We study in detail two
+factors, one being non-metricity (gravitational interaction) and the other the
+pressure anisotropy (matter variation) and their contributions to the mass,
+radius and stability of the star. Our analyses indicate that our models are
+well-behaved, singularity-free and can account for the existence of a wide
+range of observed pulsars with masses ranging from 2.08 to 2.67 $M_{\odot}$,
+with the upper value being in the so-called {\em mass gap} regime observed in
+gravitational events such as GW190814. A novel finding of this work is
+two-fold: an increase in the non-metricity factor (fixed anisotropy) leads to a
+spectrum of pulsars with radii ranging from a minimum of 10 km whereas a
+variation in anisotropy (fixed non-metricity) restricts the radii to a narrow
+window between ($12 - 13.2$) km for a 450 Hz pulsar. In addition, contributions
+from anisotropy outweigh the impact of nonmetricity in predicting the masses of
+pulsars with the ratio, $\left(\frac{M_\Delta}{M_Q}\right)_{max} \approx 2.43 $
+for low mass pulsars.",2403.20011v1
+1993-05-09,Testing for Gaussianity Through the Three Point Temperature Correlation Function,"One of the crucial aspects of density perturbations that are produced by the
+standard inflation scenario is that they are Gaussian where seeds produced by
+topological defects tend to be non-Gaussian. The three point correlation
+function of the temperature anisotropy of the cosmic microwave background
+radiation (CBR) provides a sensitive test of this aspect of the primordial
+density field. In this paper, this function is calculated in the general
+context of various allowed non-Gaussian models. It is shown that by COBE and
+the forthcoming South Pole and Balloon CBR anisotropy data may be able to test
+provide a crucial test of Gaussianity.",9305009v1
+1993-09-01,Implications of MAX for CDM,"We analyze the Gamma Ursae Minoris (GUM) and Mu Pegasii (MuP) scans of the
+Millimeter-wave Anisotropy eXperiment in the context of cold dark matter (CDM)
+models of structure formation, paying particular attention to the
+two-dimensional nature of the GUM scan. If all of the structure in the
+(foreground subtracted) data is attributed to cosmic microwave background
+anisotropy, then there is a detection in each scan. For a standard CDM model,
+the amplitudes of the signals are individually compatible with the COsmic
+Background Explorer measurement, but marginally inconsistent with each other.",9309006v1
+1993-09-28,Measuring Cosmological Parameters with Cosmic Microwave Background Experiments,"The cosmic microwave background anisotropy is sensitive to the slope and
+amplitude of primordial energy density and gravitational wave fluctuations, the
+baryon density, the Hubble constant, the cosmological constant, the ionization
+history, {\it etc.} In this Letter, we examine the degree to which these
+factors can be separately resolved from combined small- and large-angular scale
+anisotropy observations. We isolate directions of degeneracy in this cosmic
+parameter space, but note that other cosmic observations can break the
+degeneracy. (Correction to Eq. 4)",9309041v2
+1993-10-26,Gravitational Waves and the Polarisation of the Cosmic Microwave Background,"We discuss the influence of gravitational waves (GWs) upon the polarisation
+of the Cosmic Microwave Background Radiation (CMBR). We show how to compute the
+{\em rms} temperature anisotropy and polarisation of the CMBR induced by GWs of
+arbitrary wavelength. We find that the ratio of polarisation, $\Pi$, to
+anisotropy, $A$, can be as large as $\sim 40$\%, but is sensitively dependent
+upon the GW spectrum and the cosmological ionisation history. We argue that
+CMBR polarisation measurements can provide useful constraints on cosmological
+models.",9310045v1
+1994-02-16,How Well Can Cosmological Parameters Be Estimated from CMB Observations?,"The CMB anisotropy depends sensitively upon the slope and amplitude of
+primordial density and gravitational wave fluctuations, the baryon density, the
+Hubble constant, the cosmological constant, the ionization history, {\it etc.}
+We report on recent work showing how well multi-scale measurements of the
+anisotropy power spectrum can resolve these factors. We identify a hypersurface
+in cosmic parameter space that can be accurately localized by observations, but
+along which the likelihood will hardly vary. Other cosmic observations will be
+needed to break this degeneracy.",9402041v1
+1994-04-29,On Fractal Structure of Quantum Gravity and Relic Radiation Anisotropy,"It is argued that large-scale ($>7^o$) cosmic microwave background anisotropy
+detected in COBE cosmic experiment can be considered as a trace of the quantum
+gravity fractal structure.",9404076v3
+1994-06-21,Quoting Experimental Information,"There was a question raised at this meeting as to the best way to present the
+results of experiments measuring anisotropies in the CMB. Here we will make
+some simple comments about the 3 main competing methods and some suggestions.
+In particular we will give an over-simplified but hopefully useful method of
+comparing GACF numbers with other power spectra, and a simple rule-of-thumb for
+converting between the two main conventions.",9406060v1
+1994-06-27,"CBR Anisotropy in an Open Inflation, CDM Cosmogony","We compute the cosmic background radiation anisotropy, produced by
+energy-density fluctuations generated during an early epoch of inflation, in an
+open cosmological model based on the cold dark matter scenario. At $\Omega_0
+\sim$ 0.3 -- 0.4, the COBE normalized open model appears to be consistent with
+most observations.",9406069v1
+1994-07-13,Detectability of Tensor Perturbations Through CBR Anisotropy (final published version),"Detection of the tensor perturbations predicted in inflationary models is
+important for testing inflation as well as for reconstructing the inflationary
+potential. We show that because of cosmic variance the tensor contribution to
+the square of the CBR quadrupole anisotropy must be greater than about 20\% of
+the scalar contribution to ensure a statistically significant detection of
+tensor perturbations. This sensitivity could be achieved by full-sky
+measurements on angular scales of $3^{\circ}$ and $0.5^\circ$.",9407037v3
+1994-07-15,Skewness of CMB Anisotropies in an Inflationary Isocurvature Baryon Model,"We investigate the cosmic variance of the skewness of the cosmic microwave
+background (CMB) anisotropies in an inflationary model which leads to the
+baryon isocurvature scenario for the cosmic structure formation. In this model,
+the baryon number fluctuations are given by a sinusoidal function of a random
+Gaussian field. We find that the skewness is very small in comparison with that
+of the fluctuations which obey Gaussian statistics.",9407046v1
+1995-01-13,"SUB--DEGREE ANISOTROPY OBSERVATIONS: GROUND--BASED, BALLOON--BORNE AND SPACE EXPERIMENTS","Extensive, accurate imaging of the Cosmic Background Radiation temperature
+anisotropy at sub--degree angular resolution is widely recognized as one of the
+most crucial goals for cosmology and astroparticle physics in the next decade.
+We review the scientific case for such measurements in relation with sky
+coverage, attainable sensitivity, confusing foreground radiation components,
+and experimental strategies. Although ground--based and balloon--borne
+experiments will provide valuable results, only a well--designed, far--Earth
+orbit space mission covering a wide spectral range and a significant part of
+all the sky will provide decisive answers on the mechanism of structure
+formation.",9501043v1
+1995-08-16,Anisotropy of the Microwave Sky at 90 GHz: Results from Python II,"We report on additional observations of degree scale anisotropy at 90~GHz
+from the Amundsen-Scott South Pole Station in Antarctica. Observations during
+the first season with the Python instrument yielded a statistically significant
+sky signal; in this paper we report the confirmation of that signal with data
+taken in the second year, and on results from an interleaving set of fields.",9508065v1
+1995-09-02,The Topology of The Cosmic Microwave Background Anisotropy on The Scale 1 degree,"In this paper we develop the theory of clusterization of peaks in a Gaussian
+random field. We have obtained new mathematical results from this theory and
+the theory of percolation and have proposed a topological method of analysis of
+sky maps based on these results. We have simulated $10^o\times10^o$ sky maps of
+the cosmic microwave background anisotropy expected from different cosmological
+models with $0.5^o-1^o$ resolution in order to demonstrate how this method can
+be used for detection of non-Gaussian noise in the maps and detection of the
+Doppler-peak in the spectrum of perturbation of $\gD T/T$.",9509008v1
+1995-09-07,"CMB Anisotropies, Large-Scale Structure and the Future","We are now beginning to learn detailed information about cosmological
+parameters from the shapes of the matter and radiation power spectra, together
+with their relative normalization. As more high quality data are gathered from
+galaxy surveys and from microwave anisotropies, the range of allowed models is
+expected to get incrementally smaller. The amount of information potentially
+available from a high-resolution satellite experiment should allow a
+determination of essentially {\it all} currently discussed cosmological
+parameters to less than ~10%.",9509035v1
+1995-12-22,CMB Anisotropy in COBE-DMR-Normalized Open CDM Cosmogony,"We compute the CMB anisotropy in an open inflation CDM model which is
+normalized to the two-year DMR sky map. Presently available CMB data is
+consistent with $\Omega_0 \sim 0.3 - 0.4$, but does not strongly disfavour
+either $\Omega_0 \sim 0.1$ or $\Omega_0 \sim 1$. Accumulating CMB data should
+strengthen the observational discriminative power, however, a better
+understanding of systematic effects will be needed before it will be possible
+to draw robust conclusions about model viability.",9512148v1
+1996-03-15,"Comment on a Paper by Fang, Huang, and Wu","Before decoupling in the early universe, the tightly coupled photon/electron
+gas underwent acoustic oscillations. These oscillations should be visible today
+in the spectrum of anisotropies. Recently Fang, Huang, and Wu (1996) claimed
+that when random processes are accounted for, the phases of these oscillations
+are no longer coherent. In fact, they claim that the well-defined peaks will be
+completely smoothed out. We show here that their claim is incorrect. The
+standard Boltzmann treatment determining the anisotropies is sufficient; random
+processes do not change the standard result.",9603079v1
+1996-06-21,Testing Inflation with Small Scale CMB Anisotropies,"We discuss ability of the harmonic pattern of peaks in the CMB angular power
+spectrum to test inflation. By studying robust features of alternate models,
+which must all be isocurvature in nature, we reveal signatures unique to
+inflation. Inflation thus could be validated by the next generation of
+experiments.",9606138v1
+1996-07-22,A Causal Source which Mimics Inflation,"How unique are the inflationary predictions for the cosmic microwave
+anisotropy pattern? In this paper, it is asked whether an arbitrary causal
+source for perturbations in the standard hot big bang could effectively mimic
+the predictions of the simplest inflationary models. A surprisingly simple
+example of a `scaling' causal source is found to closely reproduce the
+inflationary predictions. This letter extends the work of a previous paper
+(ref. 6) to a full computation of the anisotropy pattern, including the Sachs
+Wolfe integral. I speculate on the possible physics behind such a source.",9607109v1
+1996-10-12,Cosmic Parameter Estimation Combining Sub-Degree CMB Experiments with COBE,"We describe the Bayesian-based signal-to-noise eigenmode method for
+cosmological parameter estimation, show how it can be used to optimally
+compress large CMB anisotropy data sets to manageable sizes, and apply it to
+the DMR 4-year, South Pole and Saskatchewan data, individually and in
+combination. A simple prior probability method is used to include large scale
+structure observations. Estimates of the Hubble parameter, vacuum energy
+density, baryon fraction and primordial spectral tilt derived from the combined
+data are given.",9610091v1
+1996-11-26,Radio frequency foreground emission and the separation of microwave anisotropies from foreground contamination,"The effects on CMB measurements of foreground contamination due to
+synchrotron radiation, free-free emission and discrete sources are considered.
+Estimates of the level and power spectrum of the Galactic fluctuations are made
+using low frequency maps and recent Tenerife data. New methods for achieving a
+frequency-based separation of Galactic and CMB components are discussed, and a
+positive/negative maximum entropy algorithm shown to be particularly powerful
+in this respect.",9611214v1
+1997-01-27,Tensor Anisotropies in an Open Universe,"We calculate the anisotropies in the cosmic microwave background induced by
+long-wavelength primordial gravitational waves in a universe with negative
+spatial curvature, such as are produced in the ``open inflation'' scenario. The
+impact of these results on the COBE normalization of open models is discussed.",9701210v2
+1997-03-12,"Fast Spherical Harmonic Analysis: a quick algorithm for generating and/or inverting full sky, high resolution CMB Anisotropy maps","We present a fast algorithm for generating full sky, high resolution ($\sim
+5'$) simulations of the CMB anisotropy pattern. We also discuss the inverse
+problem, that of evaluating from such a map the full set of $a_{\ell m}$'s and
+the spectral coefficients $C_\ell$. We show that using an Equidistant
+Cylindrical Projection of the sky substantially speeds up the calculations.
+Thus, generating and/or inverting a full sky, high resolution map can be easily
+achieved with present day computer technology.",9703084v1
+1997-04-18,CMB Experiment Baseline Determination by Minimizing Pixel Observations Dispersion,"This paper discusses a couple of approaches to removing instrument gain and
+baseline variation from observations of the CMB anisotropy. These techniques
+were tested on the COBE DMR data, a balloon experiment, and by monte carlo
+simulations. This work, though considered technical, is made available because
+CMB anisotropy mapping data processing is currently very active and a
+significant number of groups are working on this issue. Specifically,
+time-ordered estimates of the gain and baseline via fitting to limited sections
+of data or to the full or a large section of data are considered and compared.
+An expression is given for the correlation between pixels introduced by the
+residual baseline and removal technique.",9704193v2
+1997-06-04,Primordial torsion fields as an explanation of the anisotropy in cosmological electromagnetic propagation,"In this note we provide a simple explanation of the recent finding of
+anisotropy in electromagnetic (EM) propagation claimed by Nodland and Ralston
+(astro-ph/9704196). We consider, as a possible origin of such effect, the
+effective coupling between EM fields and some tiny background torsion field.
+The coupling is obtained after integrating out charged fermions, it is gauge
+invariant and does not require the introduction of any new physics.",9706044v2
+1997-10-24,Using White Dish CMB Anisotropy Data to Probe Open and Flat-Lambda CDM Cosmogonies,"We use data from the White Dish experiment to set limits on cosmic microwave
+background radiation anisotropies in open and spatially-flat-Lambda cold dark
+matter cosmogonies. We account for the White Dish calibration uncertainty, and
+marginalize over the offset and gradient removed from the data. Our 2-sigma
+upper limits are larger than those derived previously. These upper limits are
+consistent with those derived from the $COBE$-DMR data for all models tested.",9710270v1
+1997-11-19,The CMBR and the Seeds of Galaxies,"The Cosmic Microwave Background Radiation (CMBR) is the radiation left over
+from the hot Big Bang. Its blackbody spectrum and small anisotropy provide
+clues about the origin and early evolution of the Universe. In particular, the
+spectrum of the CMBR rules out many non-gravitational models of structure
+formation, and the anisotropy of the CMBR provides a measure of the
+gravitational potential at the time of last scattering, about 300,000 years
+after the Big Bang. The density inhomogeneities needed to produce the
+gravitational potential perturbations traced by the CMBR have grown to become
+the galaxies, clusters of galaxies, and superclusters that we see today.",9711220v1
+1997-12-05,The Two-Point Angular Correlation Function and BATSE Sky Exposure,"The Two-Point Angular Correlation Function is a standard analysis tool used
+to study angular anisotropies. Since BATSE's sky exposure (the angular sampling
+of gamma-ray bursts) is anisotropic, the TPACF should at some point identify
+anisotropies in BATSE burst catalogs due to sky exposure. The effects of BATSE
+sky exposure are thus explored here for BATSE 3B and 4B catalogs. Sky-exposure
+effects are found to be small.",9712094v1
+1997-12-15,Interferometric Observation of Cosmic Microwave Background Anisotropies,"We present a formalism for analyzing interferometric observations of Cosmic
+Microwave Background (CMB) anisotropy and polarization data. The formalism is
+based upon the ell-space expansion of the angular power spectrum favoured in
+recent years. Explicit discussions of maximum likelihood analysis, power
+spectrum reconstruction, parameter estimation, imaging and polarization are
+given. As an example, several calculations for the Degree Angular Scale
+Interferometer (DASI) and Cosmic Background Interferometer (CBI) experiments
+are presented.",9712195v2
+1998-01-13,The anisotropy of inverse beta decay and antineutrino detection,"The anisotropy of the positrons emitted in the reaction $\bar{\nu}_{e}+p\to
+n+e^{+}$ has to be taken into account for extracting an antineutrino signal in
+Superkamiokande. For the Sun, this effect allows a sensitivity to
+$\nu_{e}\to\bar{\nu}_{e}$ transition probability at the 3% level already with
+the statistics collected in the first hundred days. For a supernova in the
+Galaxy, the effect is crucial for extracting the correct ratio of $\nu-e$ to
+$\bar\nu_{e}-p$ events.",9801111v1
+1998-06-08,Cosmic Background Radiation Temperature Anisotropy: Position of First Doppler Peak,"The purpose of the Cosmic Background Radiation (CBR) experiments is to
+measure the temperature anisotropy via the autocorrelation function. The
+partial wave $l_1$ corresponding to the first Doppler peak caused by
+baryon-photon oscillations at the surface of last scattering depends on the
+present density $\Omega_0$ and the cosmological constant contribution
+$\Omega_{\Lambda}$. We discuss this dependence on the basis of perspicuous
+figures.",9806118v1
+1998-08-25,Cosmic microwave background anisotropy power spectrum statistics for high precision cosmology,"As the era of high precision cosmology approaches, the empirically determined
+power spectrum of the microwave background anisotropy, $C_l$, will provide a
+crucial test for cosmological theories. We present a unified semi-analytic
+framework for the study of the statistical properties of the $C_l$ coefficients
+computed from the results of balloon, ground based, and satellite experiments.
+An illustrative application shows that commonly used approximations {\it bias}
+the estimation of the baryon parameter $\Omega_b$ at the 1% level even for a
+satellite capturing as much as $\sim 70$% of the sky.",9808292v1
+1998-11-04,COBE-DMR constraints on a inflation model with non-minimal scalar field,"We derive the power spectra of the scalar- and tensor-type structures
+generated in a chaotic-type inflation model based on non-minimally coupled
+scalar field with a self interaction. By comparing contributions of
+both-structures to the anisotropy of the cosmic microwave background radiation
+with the four-year COBE-DMR data on quadrupole anisotropy we derive constraints
+on the ratio of self-coupling and non-minimal coupling constants, and the
+expansion rate in the inflation era, Eq. (12). The requirement of successful
+amount of inflation further constrains the relative amount of tensor-type
+contribution, Eq. (16).",9811069v1
+1999-03-23,Generating Non-Gaussian Adiabatic Fluctuations from Inflation,"As the quality of cosmological data continue to improve, it is natural to
+test the statistics of primordial fluctuations: are they Gaussian or
+non-Gaussian? I review a model which generates non-Gaussian adiabatic
+fluctuations from inflation. Current investigations suggest that there may
+possibly be a non-Gaussian signal in large angle cosmic microwave background
+anisotropy data. Statistics of microwave anisotropies could thus serve as a
+powerful probe of the very early Universe.",9903327v1
+1999-08-04,Inhomogeneous reionization and the polarization of the cosmic microwave background,"In a universe with inhomogeneous reionization, the ionized patches create a
+second order signal in the cosmic microwave background polarization anisotropy.
+This signal originates in the coupling of the free electron fluctuation to the
+quadruple moment of the temperature anisotropy. We examine the contribution
+from a simple inhomogeneous reionization model and find that the signal from
+such a process is below the detectable limits of the Planck Surveyor mission.
+However t he signal is above the fundamental uncertainty limit from cosmic
+variance, so th at a future detection with a high accuracy experiment on
+sub-arcminute scales is possible.",9908033v2
+1999-10-15,Topological Defects and CMB anisotropies : Are the predictions reliable ?,"We consider a network of topological defects which can partly decay into
+neutrinos, photons, baryons, or Cold Dark Matter. We find that the degree-scale
+amplitude of the cosmic microwave background (CMB) anisotropies as well as the
+shape of the matter power spectrum can be considerably modified when such a
+decay is taken into account. We conclude that present predictions concerning
+structure formation by defects might be unreliable.",9910290v2
+1999-11-10,Efficient Computation of CMB anisotropies in closed FRW models,"We implement the efficient line of sight method to calculate the anisotropy
+and polarization of the cosmic microwave background for scalar and tensor modes
+in almost-Friedmann-Robertson-Walker models with positive spatial curvature. We
+present new results for the polarization power spectra in such models.",9911177v2
+2000-02-11,CMB Anisotropies and the Determination of Cosmological Parameters,"I review the basic theory of the cosmic microwave background anisotropies in
+adiabatic cold dark matter cosmologies. The latest observational results on the
+CMB power spectrum are consistent with the simplest inflationary models and
+indicate that the Universe is close to spatially flat with a nearly scale
+invariant fluctuation spectrum. We are also beginning to see interesting
+constraints on the density of CDM, with a best fit value of omega_c = Omega_c
+h^2 of about 0.1. The CMB constraints, when combined with observations of
+distant Type Ia supernovae, are converging on a Lambda-dominated Universe with
+Omega_m approx 0.3 and Omega_Lambda approx 0.7.",0002249v1
+2000-03-22,Correlated mixtures of adiabatic and isocurvature cosmological perturbations,"The Cosmic Microwave Background (CMB) anisotropies measurements can provide
+many clues about the Universe. Although the common belief is that they will
+allow a very precise measurement of the cosmological parameters (that is, the
+current state of the Universe), they will alternatively give interesting
+informations about the state of the initial perturbations (that is, the state
+of the Universe at the end of inflation). In this paper, we study the
+observational consequences on the CMB anisotropies of some wide set of inital
+conditions, with a correlated mixture of adiabatic and isocurvature
+perturbations.",0003339v1
+2000-11-29,Cosmic Microwave Background in Closed Multiply Connected Universes,"We have investigated the cosmic microwave background (CMB) anisotropy in
+closed multiply connected universes
+  (flat and hyperbolic) with low matter density. We show that the COBE
+constraints on these low matter density models with non-trivial topology are
+less stringent since a large amount of CMB anisotropy on large angular scales
+can be produced due to the decay of the gravitational potential at late time.",0011539v1
+2000-11-29,Data Analysis for the Microwave Anisotropy Probe (MAP) Mission,"We present an overview of the upcoming Microwave Anisotropy Probe (MAP)
+mission, with an emphasis on those aspects of the mission that simplify the
+data analysis. The method used to make sky maps from the differential
+temperature data is reviewed and we present some of the noise properties
+expected from these maps. An overview of the method we plan to use to mine the
+angular power spectrum from the mega-pixel sky maps closes the paper.",0011555v1
+2001-04-02,Reproducing Cosmic Microwave Background anisotropies with mixed isocurvature perturbations,"Recently high quality data of the cosmic microwave background anisotropies
+have been published. In this work we study to which extent the cosmological
+parameters determined by using this data depend on assumptions about the
+initial conditions. We show that for generic initial conditions, not only the
+best fit values are very different but, and this is our main result, the
+allowed parameter range enlarges dramatically.",0104017v2
+2001-06-28,Studying the anisotropy of the gravitational wave stochastic background with LISA,"A plethora of gravitational wave stochastic backgrounds populate the
+sensitivity window of the Laser Interferometer Space Antenna. We show that LISA
+can detect the anisotropy of the background corresponding to the multipole
+moments of order l=2 and 4. The signal-to-noise ratio generated by galactic
+white dwarf binary systems could be as high as 60 for 3 yrs of integration, and
+LISA could provide valuable information on the spatial distribution of a
+variety of galactic sources. We also show that the cross-correlation of the
+data sets from two interferometers could marginally lead to meaningful
+upper-limits on the degree of isotropy of the primordial gravitational wave
+background.",0106538v1
+2001-10-09,Archeops: a large sky coverage millimeter experiment for mapping Cosmic Microwave Background anisotropies,"We present Archeops, a balloon-borne bolometer experiment designed to map a
+large part of the sky at millimeter and submillimeter wavelengths. The main
+scientific goal is to study the Cosmic Microwave Background anisotropies on all
+scales, in order to properly derive the cosmological parameters of the
+Universe. We present the sky coverage map of the first scientific flight.",0110221v1
+2001-10-30,CMB anisotropy: deviations from Gaussianity due to non-linear gravity,"Non-linear evolution of cosmological energy density fluctuations triggers
+deviations from Gaussianity in the temperature distribution of the cosmic
+microwave background. A method to estimate these deviations is proposed. N-body
+simulations -- in a $\Lambda$CDM cosmology -- are used to simulate the strongly
+non-linear evolution of cosmological structures. It is proved that these
+simulations can be combined with the potential approximation to calculate the
+statistical moments of the CMB anisotropies produced by non-linear gravity.
+Some of these moments are computed and the resulting values are different from
+those corresponding to Gaussianity.",0110664v1
+2001-11-08,Cosmic Microwave Background Anisotropy in models with Quintessence,"We study the Cosmic Microwave Background (CMB) anisotropies produced by
+cosine-type quintessence models. In our analysis, effects of the adiabatic and
+isocurvature fluctuations are both taken into account. For purely adiabatic
+fluctuations with scale invariant spectrum, we obtain a stringent constraint on
+the model parameters using the CMB data from COBE, BOOMERanG and MAXIMA.
+Furthermore, it is shown that isocurvature fluctuations have significant
+effects on the CMB angular power spectrum at low multipoles in some parameter
+space, which may be detectable in future satellite experiments. Such a signal
+may be used to test the cosine-type quintessence models.",0111159v1
+2001-12-06,What's Behind Acoustic Peaks in the Cosmic Microwave Background Anisotropies,"We give a brief review of the physics of acoustic oscillations in Cosmic
+Microwave Background (CMB) anisotropies. As an example of the impact of their
+detection in cosmology, we show how the present data on CMB angular power
+spectrum on sub-degree scales can be used to constrain dark energy cosmological
+models.",0112149v1
+2002-03-19,Dynamical effects of the neutrino gravitational clustering at Planck angular scales,"We study the CMB anisotropy induced by the non-linear perturbations in the
+massive neutrino density associated to the non-linear gravitational clustering
+proceses. Our results show that for the neutrino fraction in agreement with
+that indicated by the astroparticle and nuclear physics experiments and a
+cosmological accreting mass comparable with the mass of known clusters, the
+angular resolution and the sensitivity of the CMB anisotropy measurements from
+the Planck surveyor will allow the detection of the dynamical effects of the
+neutrino gravitational clustering.",0203306v1
+2002-04-25,New Limits on the Polarized Anisotropy of the Cosmic Microwave Background at Subdegree Angular Scales,"We update the limit from the 90 GHz PIQUE ground-based polarimeter on the
+magnitude of any polarized anisotropy of the cosmic microwave radiation. With a
+second year of data, we have now limited both Q and U on a ring of 1 degree
+radius. The window functions are broad: for E-mode polarization, the effective
+l is <l> = 191 +143 -132. We find that the E-mode signal can be no greater than
+8.4 microK (95% CL), assuming no B-mode polarization. Limits on a possible
+B-mode signal are also presented.",0204438v1
+2002-07-05,"Cosmic ray drift, the second knee and galactic anisotropies","We show that the second knee in the cosmic ray spectrum (i.e. the steepening
+occurring at $E\simeq 4\times 10^{17}$ eV) could be related to drift effects
+affecting the heaviest nuclear component, the iron group nuclei, in a scenario
+in which the knee at $3\times 10^{15}$ eV indicates the onset of drift effects
+in the lighter proton component. We also study the anisotropies resulting from
+diffusion and drift currents in the Galaxy, showing their potential relevance
+to account for the AGASA observations at $E\sim 10^{18}$ eV, before the
+extragalactic component becomes dominant.",0207143v1
+2002-09-25,"Effects of halo triaxiality, anisotropy and small scale clumping on WIMP direct detection exclusion limits","Weakly Interacting Massive Particle (WIMP) direct detection experiments are
+closing in on the region of parameter space where neutralinos may constitute
+the Galactic halo dark matter. Numerical simulations and observations of galaxy
+halos indicate that the standard Maxwellian halo model is likely to be a poor
+approximation to the dark matter distribution. We examine how halo models with
+triaxiality and/or velocity anisotropy affect exclusion limits, before
+discussing the consequences of the possible survival of small scale clumps.",0209528v2
+2002-12-12,Cosmological Constraints from a Combined Analysis of the Cluster Mass Function and Microwave Background Anisotropies,"We present constraints on several cosmological parameters from a combined
+analysis of the most recent Cosmic Microwave Background anisotropy data and the
+Sloan Digital Sky Survey cluster mass function. We find that the combination of
+the two data sets breaks several degeneracies among the parameters and provides
+the following constraints: $\sigma_8=0.76\pm0.09$,
+$\Omega_m=0.26^{+0.06}_{-0.07}$, $h=0.66^{+0.05}_{-0.06}$, $n=0.96 \pm 0.05$,
+$\tau_c=0.07^{+0.07}_{-0.05}$.",0212276v1
+2003-03-05,Is the Low CMB Quadrupole a Signature of Spatial Curvature?,"The temperature anisotropy power spectrum measured with the Wilkinson
+Microwave Anisotropy Probe (WMAP) at high multipoles is in spectacular
+agreement with an inflationary Lambda-dominated cold dark matter cosmology.
+However, the low order multipoles (especially the quadrupole) have lower
+amplitudes than expected from this cosmology, indicating a need for new
+physics. Here we speculate that the low quadrupole amplitude is associated with
+spatial curvature. We show that positively curved models are consistent with
+the WMAP data and that the quadrupole amplitude can be reproduced if the
+primordial spectrum truncates on scales comparable to the curvature scale.",0303127v2
+2003-05-12,Numerical Likelihood Analysis of Cosmic Ray Anisotropies,"A numerical likelihood approach to the determination of cosmic ray
+anisotropies is presented which offers many advantages over other approaches.
+It allows a wide range of statistically meaningful hypotheses to be compared
+even when full sky coverage is unavailable, can be readily extended in order to
+include measurement errors, and makes maximum unbiased use of all available
+information.",0305206v1
+2003-05-19,Cosmic Microwave Background and Supernova Constraints on Quintessence: Concordance Regions and Target Models,"We perform a detailed comparison of the Wilkinson Microwave Anisotropy Probe
+(WMAP) measurements of the cosmic microwave background (CMB) temperature and
+polarization anisotropy with the predictions of quintessence cosmological
+models of dark energy. We consider a wide range of quintessence models,
+including: a constant equation-of-state; a simply-parametrized, time-evolving
+equation-of-state; a class of models of early quintessence; scalar fields with
+an inverse-power law potential. We also provide a joint fit to the CBI and
+ACBAR CMB data, and the type 1a supernovae. Using these select constraints we
+identify viable, target models for further analysis.",0305334v1
+2003-05-22,Goodness--of--fit Statistics and CMB Data Sets,"Application of a Goodness--of--fit (GOF) statistic is an essential element of
+parameter estimation. We discuss the computation of GOF when estimating
+parameters from anisotropy measurements of the cosmic microwave background
+(CMB), and we propose two GOF statistics to be used when employing approximate
+band--power likelihood functions. They are based on an approximate form for the
+distribution of band--power estimators that requires only minimal experimental
+information to construct. Monte Carlo simulations of CMB experiments show that
+the proposed form describes the true distributions quite well. We apply these
+GOF statistics to current CMB anisotropy data and discuss the results.",0305428v1
+2003-05-26,Observing the CMB at High-l using the VSA and AMI,"We discuss two experiments - the Very Small Array (VSA) and the Arcminute
+MicroKelvin Imager (AMI) - and their prospects for observing the CMB at high
+angular multipoles. Whilst the VSA is primarily designed to observe primary
+anisotropies in the CMB, AMI is designed to image secondary anisotropies via
+the Sunyaev-Zel'dovich effect. The combined l-range of these two instruments is
+between l = 150 and ~10000.",0305485v1
+2003-06-20,Constraining superheavy dark matter model of UHECR with SUGAR data,"Models which associate the origin of the ultra-high energy cosmic rays
+(UHECR) with decays of relic superheavy particles predict the anisotropy of
+UHECR flux toward the Galactic center. We use the existing SUGAR data, which
+covered the Galactic center best so far, to look for such a signal and limit
+the fraction of UHECR produced by this mechanism. The absence of anisotropy
+toward the Galactic center in the SUGAR data implies at 95% confidence level
+that the fraction of SHDM-related cosmic rays should be less than 20% at
+$E>1\times10^{19}$ eV and less than 50% at $E>4\times10^{19}$ eV.",0306413v1
+2003-07-18,Model-independent dark energy test with sigma_8 using results from the Wilkinson Microwave Anisotropy Probe,"By combining the recent WMAP measurements of the cosmic microwave background
+anisotropies and the results of the recent luminosity distance measurements to
+type-Ia supernovae, we find that the normalization of the matter power spectrum
+on cluster scales, sigma_8, can be used to discriminate between dynamical
+models of dark energy (quintessence models) and a conventional cosmological
+constant model (LCDM).",0307346v2
+2003-08-12,Correlated Isocurvature Fluctuation in Quintessence and Suppressed CMB Anisotropies at Low Multipoles,"We consider cosmic microwave background (CMB) anisotropy in models with
+quintessence taking into account of isocurvature fluctuation in the
+quintessence. It is shown that, if the primordial fluctuation of the
+quintessence has a correlation with the adiabatic density fluctuations, CMB
+angular power spectrum $C_l$ at low multipoles can be suppressed without
+affecting $C_l$ at high multipoles. Possible scenario of generating correlated
+mixture of the quintessence and adiabatic fluctuations is also discussed.",0308208v2
+2003-10-15,Early Quintessence and the CMB,"We examine the cosmic microwave background (CMB) anisotropy for signatures of
+early quintessence dark energy -- a non-negligible quintessence energy density
+during the recombination and structure formation eras. In contrast to a
+$\Lambda$CDM cosmology, early quintessence leads to a larger suppression of
+structure growth. Because of this influence on the clustering of dark matter
+and the baryon-photon fluid, we may expect to find trace signals in the CMB and
+the mass fluctuation power spectrum. In detail, we demonstrate that suppressed
+clustering power on small length-scales, as suggested by the combined Wilkinson
+Microwave Anisotropy Probe (WMAP) / CMB / large scale structure data set, is
+characteristic of early quintessence.",0310412v1
+2003-11-19,Extended self-similarity of the small-scale cosmic microwave background anisotropy,"The Extended Self-Similarity (ESS) of cosmic microwave background (CMB)
+radiation has been studied using recent data obtained by the space-craft based
+Wilkinson Microwave Anisotropy Probe. Using the ESS and the high angular scale
+resolution (arcminutes) of the data it is shown that the CMB temperature space
+{\it increments} exhibit considerable and systematic declination from
+Gaussianity for high order moments at the small angular scales. Moreover, the
+CMB space increment ESS exponents have remarkably close values to the ESS
+exponents observed in turbulence (in magnetohydrodynamic turbulence).",0311444v1
+2004-05-17,Global Anisotropies in Supernova Explosions and Pulsar Recoil,"We show by two-dimensional and first three-dimensional simulations of
+neutrino-driven supernova explosions that low (l=1,2) modes can dominate the
+flow pattern in the convective postshock region on timescales of hundreds of
+milliseconds after core bounce. This can lead to large global anisotropy of the
+supernova explosion and pulsar kicks in excess of 500 km/s.",0405311v2
+2004-06-02,Mean diurnal variations of cosmic ray intensity as measured by Andyrchi air shower array and Baksan underground scintillation telescope,"The results of measuring diurnal variations of extensive air showers with
+energy above 100 TeV detected by the Andyrchi air shower array in 1995-2002 are
+presented. It is shown that solar diurnal wave of intensity is formed by
+pressure variations and Compton-Getting effect (due to the orbital motion of
+the Earth). The data on cosmic ray anisotropy of the Baksan underground
+scintillation telescope (BUST) are also presented for energies above 2.5 TeV
+covering the period 1982-1998. The diurnal sidereal wave measured by both
+Andyrchi and BUST is due to anisotropy of the cosmic rays.",0406059v1
+2004-06-21,Search for Cosmic Strings in CMB Anisotropies,"We have searched the 1st-year WMAP W-Band CMB anisotropy map for evidence of
+cosmic strings. We have set a limit of $\delta = 8 \pi G \mu / c^2 < 8.2 \times
+10^{-6}$ at 95% CL for statistical search for a significant number of strings
+in the map. We also have set a limit using the uniform distribution of strings
+model in the WMAP data with $\delta = 8 \pi G \mu / c^2 < 7.34 \times 10^{-5}$
+at 95% CL. And the pattern search technique we developed here set a limit
+$\delta = 8 \pi G \mu / c^2 < 1.54 \times 10^{-5}$ at 95% CL.",0406432v2
+2004-09-01,Full-sky correlation functions for CMB experiments with asymmetric window functions,"We discuss full-sky convolution of the instrumental beam with the CMB sky
+signal in CMB single-dish and interferometry experiments, using the method
+(Challinor et al. 2000) that the measured temperature and polarization
+anisotropies are defined globally on the group manifold of the
+three-dimensional rotation by means of Wigner D-functions. We re-derive the
+anisotropy and polarization correlation functions incorporated with asymmetric
+window functions, which are then explicitly calculated for a single-dish
+elliptical Gaussian beam and an interferometric Gaussian beam.",0409007v2
+2004-11-01,Magnetic turbulence in compressible fluids,"We present high resolution numerical simulations of compressible
+magnetohydrodynamic (MHD) turbulence. We concentrate on studies of spectra and
+anisotropy of velocity and density. We describe a technique of separating
+different magnetohydrodynamic (MHD) modes (slow, fast and Alfven) and apply it
+to our simulations. For the mildly supersonic case, velocity and density show
+anisotropy. However, for the highly supersonic case, we observe steepening of
+the slow mode velocity spectrum and isotropization of density. Our present
+studies show that the spectrum of density gets substantially
+  {\it flatter} than the Kolmogorov one.",0411031v1
+2005-04-18,Rotation and anisotropy of galaxies revisited,"The use of the tensor virial theorem (TVT) as a diagnostic of anisotropic
+velocity distributions in galaxies is revisited. The TVT provides a rigorous
+global link between velocity anisotropy, rotation and shape, but the quantities
+appearing in it are not easily estimated observationally. Traditionally use has
+been made of a centrally averaged velocity dispersion and the peak rotation
+velocity. Although this procedure cannot be rigorously justified, tests on
+model galaxies show that it works surprisingly well. With the advent of
+integral-field spectroscopy it is now possible to establish a rigorous
+connection between the TVT and observations. The TVT is reformulated in terms
+of sky-averages, and the new formulation is tested on model galaxies.",0504387v1
+2005-09-29,Footprints of Statistical Anisotropies,"We propose and develop a formalism to describe and constrain statistically
+anisotropic primordial perturbations. Starting from a decomposition of the
+primordial power spectrum in spherical harmonics, we find how the temperature
+fluctuations observed in the CMB sky are directly related to the coefficients
+in this harmonic expansion. Although the angular power spectrum does not
+discriminate between statistically isotropic and anisotropic perturbations, it
+is possible to define analogous quadratic estimators that are direct measures
+of statistical anisotropy. As a simple illustration of our formalism we test
+for the existence of a preferred direction in the primordial perturbations
+using full-sky CMB maps. We do not find significant evidence supporting the
+existence of a dipole component in the primordial spectrum.",0509893v1
+2005-12-19,The Full Second-Order Radiation Transfer Function for Large-Scale CMB Anisotropies,"We calculate the full second-order radiation transfer function for Cosmic
+Microwave Background anisotropies on large angular scales in a flat universe
+filled with matter and cosmological constant. It includes (i) the second-order
+generalization of the Sachs-Wolfe effect, and of (ii) both the early and late
+Integrated Sachs-Wolfe effects, (iii) the contribution of the second-order
+tensor modes, and is valid for a generic set of initial conditions specifying
+the level of primordial non-Gaussianity.",0512481v1
+2006-02-14,Contribution of a nearby Pulsar to Cosmic Rays observed at Earth,"Contribution of nearby pulsars to the cosmic rays observed at Earth has been
+studied. It is found that the experimental bound on amplitude of cosmic ray
+anisotropy may produce significant constraint on the efficiency of converting
+pulsar rotational energy to emitted particles kinetic energy. Cosmic ray fluxes
+from two well known nearby gamma ray pulsars, namely the Vela and Geminga
+pulsars, are estimated. The analysis suggests that observed bound on cosmic ray
+anisotropy restricts the contributions of the Vela and the Geminga pulsars to
+at most 1 % of the observed cosmic rays below the knee.",0602301v1
+2006-05-01,Anisotropy of the primary cosmic-ray flux in Super-Kamiokande,"A first-ever 2-dimensional celestial map of primary cosmic-ray flux was
+obtained from 2.10x10^8 cosmic-ray muons accumulated in 1662.0 days of
+Super-Kamiokande. The celestial map indicates an (0.104 \pm 0.020)% excess
+region in the constellation of Taurus and a -(0.094 \pm 0.014)% deficit region
+toward Virgo. Interpretations of this anisotropy are discussed.",0605020v2
+2006-06-27,Cosmological science enabled by Planck,"Planck will be the first mission to map the entire cosmic microwave
+background (CMB) sky with mJy sensitivity and resolution better than 10'. The
+science enabled by such a mission spans many areas of astrophysics and
+cosmology. In particular it will lead to a revolution in our understanding of
+primary and secondary CMB anisotropies, the constraints on many key
+cosmological parameters will be improved by almost an order of magnitude (to
+sub-percent levels) and the shape and amplitude of the mass power spectrum at
+high redshift will be tightly constrained.",0606643v1
+2006-07-07,Testing Global Isotropy of Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Data: Temperature Analysis,"We examine statistical isotropy of large scale anisotropies of the Internal
+Linear Combination (ILC) map, based on three year WMAP data. Our study reveals
+no significant deviation from statistical isotropy on large angular scales of
+3-year ILC map. Comparing statistical isotropy of 3-year ILC map and 1-year ILC
+map, we find a significant improvement in 3-year ILC map which can be due to
+the gain model, improved ILC map processing and foreground minimization.",0607153v1
+2006-09-20,The signature of local cosmic structures on the ultra-high energy cosmic ray anisotropies,"Current experiments collecting high statistics in ultra-high energy cosmic
+rays (UHECRs) are opening a new window on the universe facing the possibility
+to perform UHECR astronomy. Here we discuss a large scale structure (LSS) model
+for the UHECR origin for which we evaluate the expected large scale anisotropy
+in the UHECR arrival distribution. Employing the IRAS PSCz catalogue as tracer
+of the LSS, we derive the minimum statistics needed to reject or assess the
+correlation of the UHECRs with the baryonic distribution in the universe, in
+particular providing a forecast for the Auger experiment.",0609577v1
+2006-12-12,CMB Alignment in Multi-Connected Universes,"The low multipoles of the cosmic microwave background (CMB) anisotropy
+possess some strange properties like the alignment of the quadrupole and the
+octopole, and the extreme planarity or the extreme sphericity of some
+multipoles, respectively. In this paper the CMB anisotropy of several
+multi-connected space forms is investigated with respect to the maximal angular
+momentum dispersion and the Maxwellian multipole vectors in order to settle the
+question whether such spaces can explain the low multipole anomalies in the
+CMB.",0612308v1
+2006-12-23,Hemispherical transport equation: modeling of quasiparallel collisionless shocks,"Using a so-called hemispherical model we derive a general transport equation
+for cosmic ray and thermal particles scattered in pitch angle by magnetic
+inhomogeneities in a moving collisionless plasma. The weak scattering through
+90 degrees results in isotropic particle distributions in each hemisphere. The
+consideration is not limited by small anisotropies and by the condition that
+particle velocities are higher than characteristic flow velocity differences.
+For high velocities and small anisotropies the standard cosmic ray transport
+equation is recovered. We apply the equations derived for investigation of
+injection and acceleration of particles by collisionless shocks.",0612715v1
+1992-04-21,Image of the Energy Gap Anisotropy in the Vibrational Spectum of a High Temperature Superconductor,"We present a new method of determining the anisotropy of the gap function in
+layered high-Tc superconductors. Careful inelastic neutron scattering
+measurements at low temperature of the phonon dispersion curves in the (100)
+direction in La_(1.85)Sr_(.15)CuO_4 would determine whether the gap is
+predominately s-wave or d-wave. We also propose an experiment to determine the
+gap at each point on a quasi-two-dimensional Fermi surface.",9204008v1
+1993-02-09,Kinetics of Ordering in Cu3Au: An Atomistic Approach,"We study the kinetics of ordering in Cu3Au using a model Hamiltonian derived
+from the effective medium theory of chemical bonding. Monte Carlo simulations
+are used to investigate universal and non-universal features of the growth
+kinetics. Anisotropic scaling of the structure factor is observed in late-stage
+growth of ordered domains. The anisotropy is a non-universal feature determined
+by details of the microscopic model, and we find that the anisotropy observed
+in the simulations is in excellent agreement with experiments on Cu3Au. The
+simulations are discussed in the context of theories of unstable growth. To our
+knowledge, this is the first study of kinetics in a realistic model Hamiltonian
+describing the material-specific properties of Cu3Au.",9302014v1
+1993-08-13,Boundary-induced anisotropy of the avalanches in the sandpile automaton,"We study numerically the avalanches in a two--dimensional critical height
+sandpile model with sand grains added at the center of the system. Smaller
+avalanches near the center of the system are isotropic. Larger avalanches are,
+however, affected by the boundary of the system, to a degree that increases
+with the avalanche size. Up to linear system size $L=1001$, we did not find an
+obvious indication for lattice--induced anisotropy.",9308021v1
+1994-06-07,Temperature Dependent Gap Anisotropy from Interlayer Tunneling,"A recent experiment by Ma and collaborators shows that the gap anisotropy in
+${\rm Bi}_2 {\rm Sr}_2 {\rm Ca}_1 {\rm Cu}_2 {\rm O}_{8+x}$ is strongly
+temperature dependent. In particular, the superconducting gap along the $\Gamma
+- M$ direction shows a weaker temperature dependence than the gap along the
+$\Gamma - X$ direction which decreases rapidly with temperature. We explain
+this novel feature as a natural consequence of the interlayer tunneling
+mechanism of superconductivity.",9406046v1
+1994-09-19,The Role of Spin Anisotropy in the Unbinding of Interfaces,"We study the ground state of a classical X-Y model with $p \ge 3$-fold spin
+anisotropy $D$ in a uniform external field, $H$. An interface is introduced
+into the system by a suitable choice of boundary conditions. For large $D$, as
+$H \to 0$, we prove using an expansion in $D^{-1}$ that the interface unbinds
+from the surface through an infinite series of layering transitions. Numerical
+work shows that the transitions end in a sequence of critical end points.",9409078v1
+1994-10-27,Multiparticle Reactions with Spatial Anisotropy,"We study the effect of anisotropic diffusion on the one-dimensional
+annihilation reaction kA->inert with partial reaction probabilities when
+hard-core particles meet in groups of k nearest neighbors. Based on scaling
+arguments, mean field approaches and random walk considerations we argue that
+the spatial anisotropy introduces no appreciable changes as compared to the
+isotropic case. Our conjectures are supported by numerical simulations for slow
+reaction rates, for k=2 and 4.",9410103v1
+1995-04-05,Josephson Junction Ladders: Ground State and Relaxation Phenomena,"This paper considers a Josephson Junction array with the geometry of a ladder
+and anisotropy in the Josephson couplings. The ground state problem for the
+ladder corresponds to the one for the one-dimensional chiral XY model in a
+two-fold anisotropy field, which allows of a rigorous characterization of the
+ground state phase diagram and the relevant elementary excitations for the
+system. The approach to equilibrium, which we study using Langevin dynamics,
+shows slow relaxation, typical of systems whose energy landscape in the
+configuration space consists of a wealthy of metastable states, dynamically
+disconnected.",9504015v1
+1995-08-23,Acoustic Attenuation in High-$T_c$ Superconductors,"We analyze the acoustic attenuation rate in high-$T_c$ superconductors, and
+find that this method offers an additional way to examine the anisotropy of the
+superconducting order parameter in these materials. We argue that it should be
+possible to distinguish the electronic contribution to the acoustic
+attenuation, which has a strong temperature dependence near $T_c$, from the
+lattice contribution, which does not show a strong temperature dependence near
+$T_c$. We propose that this can be utilized to measure the anisotropy of the
+order parameter by measuring the attenuation rate near $T_c$ in different
+directions.",9508102v1
+1995-08-29,Characterization of the reorientation transition in classical Heisenberg models with dipole interaction,"In this paper the thermodynamics of thin ferromagnetic films are studied in
+the framework of the classical Heisenberg model with uniaxial anisotropy and
+long--range dipole interaction. The dependence of the order of the
+reorientation transition in these systems on the number of layers and on the
+distribution of anisotropies is investigated using both mean field theory and
+Monte-Carlo simulations.",9508131v1
+1995-09-08,Heat Transport and the Nature of the Order Parameter in Superconducting $UPt_3$,"Recent thermal conductivity data on the heavy fermion superconductor $UPt_3$
+have been interpreted as offering support for an $E_{2u}$ model of the order
+parameter as opposed to an $E_{1g}$ model. In this paper, we analyze this issue
+from a theoretical standpoint including the detailed effects of Fermi surface
+and gap anisotropy. Our conclusion is that although current data put strong
+constraints on the gap anisotropy, they cannot definitively distinguish between
+these two models. Measurements on samples of varying quality could be decisive
+in this regard, however.",9509045v1
+1996-06-03,Vortex-Loop Unbinding and Flux-Line Lattice Melting in Superconductors,"We study the interplay between a novel vortex-loop unbinding in finite
+magnetic field at T=T_V and flux-line lattice (FLL) melting at T=T_M in type-II
+superconductors. The FLL melts due to nucleation of vortex loops parallel to
+c-axis, connected to flux lines. For moderate anisotropy, phase coherence along
+c-axis is lost at T_V > T_M due to an ab-plane vortex-loop unbinding with loops
+located close to thermal FLL fluctuations. For large anisotropy, phase
+coherence along c-axis is lost at T_V < T_M due to nucleation of ab-plane
+vortex-loops uncorrelated to flux lines.",9606002v1
+1996-07-30,The phase diagram of high-Tc's: Influence of anisotropy and disorder,"We propose a phase diagram for the vortex structure of high temperature
+superconductors which incorporates the effects of anisotropy and disorder. It
+is based on numerical simulations using the three-dimensional Josephson
+junction array model. We support the results with an estimation of the internal
+energy and configurational entropy of the system. Our results give a unified
+picture of the behavior of the vortex lattice, covering from the very
+anysotropic BiSrCaCuO to the less anisotropic YBaCuO, and from the first order
+melting ocurring in clean samples to the continuous transitions observed in
+samples with defects.",9607219v1
+1996-09-20,Exact results for quantum phase transitions in random XY spin chains,"The effect of disorder on the quantum phase transitions induced by a
+transverse field, anisotropy, and dimerization in XY spin chains is
+investigated. The low-energy behavior near the critical point is described by a
+Dirac-type equation with a random mass for which an exact analytic treatment is
+possible. Results obtained for the dynamical critical exponent, the specific
+heat, and transverse susceptibility agree with results recently obtained using
+a real space renormalization group decimation technique, supporting Fisher's
+claim that it is exact. A non-zero transverse field changes the universality
+class of the anisotropy transition.",9609195v1
+1996-10-30,A unified treatment of Ising model magnetizations,"We show how the spontaneous bulk, surface and corner magnetizations in the
+square lattice Ising model can all be obtained within one approach. The method
+is based on functional equations which follow from the properties of corner
+transfer matrices and vertex operators and which can be derived graphically. In
+all cases, exact analytical expressions for general anisotropy are obtained.
+Known results, including several for which only numerical computation was
+previously possible, are verified and new results related to general anisotropy
+and corner angles are obtained.",9610212v2
+1997-01-08,Reorientation transition of ultrathin ferromagnetic films,"We demonstrate that the reorientation transition from out-of-plane to
+in-plane magnetization with decreasing temperature as observed experimentally
+in Ni-films on Cu(001) can be explained on a microscopic basis. Using a
+combination of mean field theory and perturbation theory, we derive an analytic
+expression for the temperature dependent anisotropy. The reduced magnetization
+in the film surface at finite temperatures plays a crucial role for this
+transition as with increasing temperature the influence of the uniaxial
+anisotropies is reduced at the surface and is enhanced inside the film.",9701043v2
+1997-01-10,Effect of Anisotropy on the Localization in a Bifractal System,"Bifractal is a highly anisotropic structure where planar fractals are stacked
+to form a 3-dimensional lattice. The localization lengths along fractal
+structure for the Anderson model defined on a bifractal are calculated. The
+critical disorder and the critical exponent of the localization lengths are
+obtained from the finite size scaling behavior. The numerical results are in a
+good agreement with previous results which have been obtained from the
+localization lengths along the perpendicular direction. This suggests that the
+anisotropy of the embedding lattice structure is irrelevant to the critical
+properties of the localization.",9701065v1
+1997-10-30,Magnetization plateau in S=3/2 antiferromagnetic Heisenberg chain with anisotropy,"The magnetization process of the S=3/2 antiferromagnetic Heisenberg chain
+with the single-ion anisotropy D at T=0 is investigated by the exact
+diagonalization of finite clusters and finite-size scaling analyses. It is
+found that a magnetization plateau appears at m=1/2 for $D>D_c=0.93 \pm 0.01$.
+The phase transition with respect to D at D_c is revealed to be the
+Kosterlitz-Thouless-type. The magnetization curve of the infinite system is
+also presented for some values of D.",9710327v1
+1997-12-15,Shape anisotropy and magnetic domain structures in striped monolayers,"We study the effect of dipolar interactions on a magnetic striped monolayer
+with a microscopic unit cell of square symmetry, and of size $(N_x\times N_y)$
+spins. Even if the aspect ratio $r=N_x/N_y$ is very large, an in-plane shape
+anisotropy is always negligible, except if $N_y$ is fairly small $(N_y<40)$.
+In-plane domains are not possible, except for values of the dipolar coupling
+larger than the domain wall energy.",9712158v1
+1997-12-17,Domain structures in ultrathin magnetic films,"Domain structures appear in ultrathin magnetic films, if an easy-axis
+anisotropy, favouring the direction perpendicular to the film, overcomes the
+shape anisotropy. We will study the nature of the magnetic ground state and how
+the different parameters influence the domain structure. Both Ising and
+Heisenberg spins will be considered: in the latter case, a reorientation phase
+transition may take place. Domains are expected to appear just before such
+transition. Domain structures at finite temperature will be described in terms
+of a two dimensional array of domain walls, whose behaviour resembles a liquid
+crystal.",9712207v1
+1998-01-13,Skyrmion in a real magnetic film,"Skyrmions are the magnetic defects in an ultrathin magnetic film, similar to
+the bubble domains in the thicker films. Even weak uniaxial anisotropy
+determines its radius unambiguously. We consider the dynamics of the skyrmion
+decay. We show that the discreteness of the lattice in an isotropic 2D magnet
+leads to a slow rotation of the local magnetization in the skyrmion and,
+provided a small dissipation, to decay of the skyrmion. The radius of such a
+skyrmion as a function of time is calculated. We prove that uniaxial anisotropy
+stabilizes the skyrmion and study the relaxation process.",9801114v1
+1998-01-27,Electronic Structure of Ladder Cuprates,"We study the electronic structure of the ladder compounds (SrCa)CuO 14-24-41
+and SrCuO 123. LDA calculations for both give similar Cu 3d-bands near the
+Fermi energy. The hopping parameters estimated by fitting LDA energy bands show
+a strong anisotropy between the t_perp t_par intra-ladder hopping and small
+inter-ladder hopping. A downfolding method shows that this anisotropy arises
+from the ladder structure.The conductivity perpendicular to the ladders is
+computed assuming incoherent tunneling giving a value close to experiment.",9801280v1
+1998-02-12,Behavior of a polymer chain in a critical binary solvent,"We present a field-theoretic renormalization group analysis of a polymer
+chain immersed in a binary good solvent close to its critical demixing point.
+We first show that this problem can be mapped on a bicritical field theory,
+i.e. a $(\Phi^{2})^{2}$-model with a mass anisotropy. This implies that the
+end-to-end distance of the polymer is now controlled by a new critical exponent
+$\nu_{B}$ related to the quadratic mass anisotropy operator $B$. To show this
+we solve the RG equation and calculate explicitly the exponents and the mean
+end-to-end length of the chain.",9802130v1
+1998-03-02,Field induced transition of the S=1 antiferromagnetic chain with anisotropy,"The ground state magnetization process of the S=1 antiferromagnetic chain
+with the easy-axis single-ion anisotropy described by negative $D$ is
+investigated. It is numerically found that a phase transition between two
+different gapless phases occurs at an intermediate magnetic field between the
+starting and saturation points of the magnetization for $-1.49<D<-0.35$. The
+transition is similar to the spin flopping, but it is second-order and not
+accompanied with any significant anomalous behaviors in the magnetization
+curve. We also present the phase diagrams in the m-D and H-D planes which
+reveal a possible re-entrant transition.",9803022v2
+1998-03-31,Crossover between polariton and phonon local states. Anisotropy-induced localization threshold,"We consider the impurity-induced polariton local states in a dipole-active
+medium. These states present the local optical vibrations which are coherently
+coupled with the induced electromagnetic field. We show that the crossover
+between the polariton and phonon local states takes place within the
+relativistically narrow interval near the bottom of the polariton gap. However,
+the resonant phonon-photon interaction leads to the absence of the lower
+threshold of the impurity strength. These results are due to the singularity of
+the density of the polariton states, which is generic for any isotropic
+dipole-active phonon mode with the negative dispersion. We show that a weak
+anisotropy removes this singularity and sets a finite threshold for the local
+polariton states.",9803375v1
+1998-04-06,Stochastic equation for the erosion of inclined topography,"We present a stochastic equation to model the erosion of topography with
+fixed inclination. The inclination causes the erosion to be anisotropic. A
+zero-order consequence of the anisotropy is the dependence of the prefactor of
+the surface height-height correlations on direction. The lowest higher-order
+contribution from the anisotropy is studied by applying the dynamic
+renormalization group. In this case, assuming an inhomogenous distribution of
+soil material, we find a one-loop estimate of the roughness exponents. The
+predicted exponents are in good agreement with new measurements made from
+seafloor topography.",9804066v1
+1998-05-21,Two-Coupled Chains with Spin-Anisotropic Backward Scattering,"By applying renormalization group method to the bosonized Hamiltonian of
+two-coupled chains with repulsive intrachain interaction, we have examined a
+role of backward scattering with a spin-anisotropy which competes with
+interchain hopping. From calculation of a dominant state in the limit of low
+energy, it is found that superconducting state moves into spin density wave
+state when the anisotropy becomes larger than a critical value. Further phase
+diagram is shown on the plane of g-ology.",9805270v2
+1998-10-31,The Kosterlitz-Thouless and magnetic transition temperatures in layered magnets with a weak easy-plane anisotropy,"The two-dimensional (2D) Heisenberg magnet with a weak easy-plane anisotropy
+is considered. A renormalization group (RG) analysis in this model is performed
+for both quantum and classical cases. A crossover from the Heisenberg to 2D XY
+model is discussed. The magnetic transition owing to the interlayer coupling is
+considered. Analytical results for the Kosterlitz-Thouless and Curie (Neel)
+temperatures are derived with account of two-loop corrections. The results are
+compared with experimental data, e.g. on K2CuF4, and turn out to provide a
+quantitative description, unlike the standard one-loop results.",9811003v1
+1998-12-04,Fundamental constraints for the mechanism of superconductivity in cuprates,"Considerable progress has been made over the last decade in understanding the
+phenomenological properties of the cuprate high-T$_{c}$ superconductors and in
+producing well characterized high quality materials. Nevertheless, the pairing
+mechanism itself remains controversial. We establish a criterion to test
+theories for layered superconductors relying on a substantial interlayer
+contribution. The criterion is based on the ratio of the interlayer
+contribution to the total superfluid density, which is traced back to the
+inverse squared effective mass anisotropy. The anisotropy can be measured
+rather accurately by various experimental techniques. It turns out that models
+relying on interlayer pairing cannot be considered as serious candidates for
+the mechanism of superconductivity in cuprate superconductors.",9812081v1
+1999-01-04,On the magnetoresistance anisotropy of a 2-dimensional electron gas with large half-integer filling factors,"The unsymmetric confinement of the electrons in a typical 2-dimensional
+electron gas (2DEG) breaks the full cubic symmetry of the in-plane transport
+properties. A rigorous invariance of the transport under rotation by pi/2 about
+the cubic axis perpendicular to the plane of the gas no longer holds, even for
+structurally perfect samples, and asymmetries under rotation by pi/2 are
+allowed. It is proposed that this symmetry breaking plays a role in the recent
+observation, by Little et al., of the pronounced anisotropy of the
+magnetoresistance of a 2DEG at very low temperatures, at large half-integer
+filling factors of the Landau levels in such a system.",9901016v1
+1999-02-22,Broken Symmetries in Scanning Tunneling Images of Carbon Nanotubes,"Scanning tunneling images of carbon nanotubes frequently show electron
+distributions which break the local sixfold symmetry of the graphene sheet. We
+present a theory of these images which relates these anisotropies to the off
+diagonal correlations in the single particle density matrix, and allows one to
+extract these correlations from the observed images. The theory is applied to
+images of the low energy states reflected at the end of a tube or by point
+defects, and to states propagating on defect free semiconducting tubes. The
+latter exhibit a novel switching of the anisotropy in the tunneling image with
+the sign of the tunneling bias.",9902303v1
+1999-03-28,Anisotropic Transport of Two-Dimensional Holes in High Landau Levels,"Magnetoresistance data taken along $[\bar{2}33]$ and $[01\bar{1}]$ directions
+in a GaAs/AlGaAs two-dimensional hole sample with van der Pauw geometry exhibit
+significant anisotropy at half-integer filling factors. The anisotropy appears
+to depend on both the density and symmetry of the hole charge distribution.",9903405v2
+1999-04-01,First principles calculation of uniaxial magnetic anisotropy and magnetostriction in strained CMR films,"We performed first - principles relativistic full-potential linearized
+augmented plane wave calculations for strained tetragonal ferromagnetic
+La(Ba)MnO$_3$ with an assumed experimental structure of thin strained
+tetragonal La$_{0.67}$Ca$_{0.33}$MnO$_3$ (LCMO) films grown on SrTiO$_3$[001]
+and LaAlO$_3$[001] substrates. The calculated uniaxial magnetic anisotropy
+energy (MAE) values, are in good quantitative agreement with experiment for
+LCMO films on SrTiO$_3$ substrate. We also analyze the applicability of linear
+magnetoelastic theory for describing the stain dependence of MAE, and estimate
+magnetostriction coefficient $\lambda_{001}$.",9903460v1
+1999-04-19,"Dynamic transverse susceptibility in Au-Fe-Au ""nano-onions""","A precision radio-frequency (RF) transverse modulation technique based on a
+resonant tunnel diode oscillator (TDO) has been used to study the dynamic
+susceptibility in novel ring-shaped single domain Fe nanoparticles synthesized
+using reverse-micelle chemistry. Hysteresis loops measured using a SQUID
+magnetometer indicate a large coercivity (Hc = 400Oe) below the blocking
+temperature (TB ~52K). The dynamic susceptibility shows remarkable consistency
+with the M-H data and exhibits peaks at characteristic anisotropy fields.
+Overall, these RF experiments are well suited to probe the magnetic anisotropy
+in nanophase materials.",9904267v1
+1999-04-30,Does spin-orbit coupling play a role in metal-nonmetal transition in two-dimensional systems?,"We propose an experiment, which would allow to pinpoint the role of
+spin-orbit coupling in the metal-nonmetal transition observed in a number of
+two-dimensional systems at low densities. Namely, we demonstrate that in a
+parallel magnetic field the interplay between the spin-orbit coupling and the
+Zeeman splitting leads to a characteristic anisotropy of resistivity with
+respect to the direction of the in-plane magnetic field. Though our analytic
+calculation is done in the deeply insulating regime, the anisotropy is expected
+to persist far beyond that regime.",9904451v2
+1999-05-21,Breakdown of a Magnetization Plateau due to Anisotropy in Heisenberg Mixed-Spin Chains,"We discuss the critical behavior of the spin-(1,1/2) Heisenberg ferrimagnetic
+chain in a magnetic field, whose magnetization curve exhibits a plateau at a
+third of the full magnetization. A bond alternation stabilizes the massive
+state, whereas an exchange anisotropy causes the breakdown of the plateau and
+the onset of a gapless spin-fluid state, where the transition, lying in the XY
+but ferromagnetic region, is of Kosterlitz-Thouless type. In order to elucidate
+significant quantum effects, we investigate the model of classical version as
+well.",9905311v1
+1999-07-20,Conductivity of Layered Crystals,"We show that the resistive anisotropy of an anisotropic medium is determined
+by the ratio of the phase coherence lengths. In layered crystals in which the
+interlayer transport is incoherent, the out-of-plane phase coherence length is
+fixed and temperature independent. This leads to a temperature dependent
+resistive anisotropy and to the coexistence of metallic in-plane and
+non-metallic out-of-plane conductivities. Our approach provides a description
+of the c-axis conductivity in the highly nonclassical regime, characteristic of
+layered cuprates.",9907306v1
+1999-11-23,Magnetization-plateau state of the S=3/2 spin chain with single ion anisotropy,"We reexamine the numerical study of the magnetized state of the S=3/2 spin
+chain with single ion anisotropy D(> 0) for the magnetization M=M_{S}/3, where
+M_{S} is the saturation magnetization. We find at this magnetization that for
+D<D_{c1}=0.387 the system is critical and the magnetization plateau does not
+appear. For D > D_{c1}, the parameter region is divided into two parts D_{c1} <
+D < D_{c2}=0.943 and D_{c2} < D. In each region, the system is gapful and the
+M=M_{S}/3 magnetization plateau appears in the magnetization process. From our
+numerical calculation, the intermediate region D_{c1} < D < D_{c2} should be
+characterized by a magnetized valence-bond-solid state.",9911364v1
+1999-12-13,Spin Anisotropy and Quantum Hall Effect in the Kagome Lattice - Chiral Spin State based on a Ferromagnet-,"A ferromagnet with spin anisotropies on the 2D Kagome lattice is
+theoretically studied. This is a typical example of the flat-band ferromagnet.
+The Berry phase induced by the tilting of the spins opens the band gap and
+quantized Hall conductance \sigma_{xy}=\pm e^2/h is realized without external
+magnetic field. This is the most realistic chiral spin state based on the
+ferromagnetism. We also discuss the implication of our results to anomalous
+Hall effect observed in the metallic pyrochlore ferromagnets R_2Mo_2O_7(R=Nd,
+Sm, Gd).",9912206v1
+2000-01-14,Anisotropy of the Energy Gap in the Insulating Phase of the U-t-t' Hubbard Model,"We apply a diagrammatic expansion method around the atomic limit (U >> t) for
+the U-t-t' Hubbard model at half filling and finite temperature by means of a
+continued fraction representation of the one-particle Green's function. From
+the analysis of the spectral function A(\vec{k},\omega) we find an energy
+dispersion relation with a (cos k_x-cos k_y)^2 modulation of the energy gap in
+the insulating phase. This anisotropy is compared with experimental ARPES
+results on insulating cuprates.",0001210v2
+2000-02-09,Fluctuating spin g-tensor in small metal grains,"In the presence of spin-orbit scattering, the splitting of an energy level in
+a generic small metal grain due to the Zeeman coupling to a magnetic field B
+depends on the direction of B, as a result of mesoscopic fluctuations. The
+anisotropy is described by the eigenvalues g_j^2 (j=1,2,3) of a tensor G,
+corresponding to the (squares of) g-factors along three principal axes. We
+consider the statistical distribution of G and find that the anisotropy is
+enhanced by eigenvalue repulsion between the g_j.",0002139v1
+2000-02-10,Shape anisotropy and Voids,"Numerical simulations on a 2-dimensional model system showed that voids are
+induced primarily due to shape anisotropy in binary mixtures of interacting
+disks. The results of such a simple model account for the key features seen in
+a variety of flux experiments using liposomes and biological membranes.",0002148v1
+2000-03-02,Spinning up and down a Boltzmann gas,"Using the average method, we derive a close set of linear equations that
+describes the spinning up of an harmonically trapped gas by a rotating
+anisotropy. We find explicit expressions for the needed to transfer angular
+momentum as well as the decay time induced by a static residual anisotropy.
+These different time scales are compared with the measured nucleation time and
+lifetime of vortices by the ENS group. We find a good agreement that may
+emphasize the role played by the non-condensed component in thoses experiments.",0003024v1
+2000-03-17,Spin-triplet superconductivity due to antiferromagnetic spin-fluctuation in Sr_2RuO_4,"A mechanism leading to the spin-triplet superconductivity is proposed based
+on the antiferromagnetic spin fluctuation. The effects of anisotropy in spin
+fluctuation on the Cooper pairing and on the direction of d vector are examined
+in the one-band Hubbard model with RPA approximation. The gap equations for the
+anisotropic case are derived and applied to Sr_2RuO_4. It is found that a
+nesting property of the Fermi surface together with the anisotropy leads to the
+triplet superconductivity with the d=z(sin{k_x}\pm isin{k_y}), which is
+consistent with experiments.",0003296v1
+2000-03-30,Observation of harmonic generation and nonlinear coupling in the collective dynamics of a Bose condensate,"We report the observation of harmonic generation and strong nonlinear
+coupling of two collective modes of a condensed gas of rubidium atoms. Using a
+modified TOP trap we changed the trap anisotropy to a value where the frequency
+of the m=0 high-lying mode corresponds to twice the frequency of the m=0
+low-lying mode, thus leading to strong nonlinear coupling between these modes.
+By changing the anisotropy of the trap and exciting the low-lying mode we
+observed significant frequency shifts of this fundamental mode and also the
+generation of its second harmonic.",0003495v1
+2000-06-23,Importance of Correlation Effects on Magnetic Anisotropy in Fe and Ni,"We calculate magnetic anisotropy energy of Fe and Ni by taking into account
+the effects of strong electronic correlations, spin-orbit coupling, and
+non-collinearity of intra-atomic magnetization. The LDA+U method is used and
+its equivalence to dynamical mean-field theory in the static limit is
+emphasized. Both experimental magnitude of MAE and direction of magnetization
+are predicted correctly near U=4 eV for Ni and U=3.5 eV for Fe. Correlations
+modify one-electron spectra which are now in better agreement with experiments.",0006385v1
+2000-07-10,Experimental evidence for the formation of stripe phases in Si/SiGe,"We observe pronounced transport anisotropies in magneto-transport experiments
+performed in the two-dimensional electron system of a Si/SiGe heterostructure.
+They occur when an in-plane field is used to tune two Landau levels with
+opposite spin to energetic coincidence. The observed anisotropies disappear
+drastically for temperatures above 1 K. We propose that our experimental
+findings may be caused by the formation of a unidirectional stripe phase
+oriented perpendicular to the in-plane field.",0007148v1
+2000-07-14,Dissipative dynamics of vortex arrays in anisotropic traps,"We discuss the dissipative dynamics of vortex arrays in trapped
+Bose-condensed gases and analyze the lifetime of the vortices as a function of
+trap anisotropy and the temperature. In particular, we distinguish the two
+regimes of the dissipative dynamics, depending on the relative strength of the
+mutual friction between the vortices and the thermal component, and the
+friction of the thermal particles on the trap anisotropy. We study the effects
+of heating of the thermal cloud by the escaping vortices on the dynamics of the
+system.",0007246v1
+2000-09-22,Highly anisotropic commensurability oscillations in two-dimensional holes at the GaAs/AlGaAs (311)A interface,"Measurements of commensurability oscillations in GaAs/AlGaAs two-dimensional
+(2D) hole systems grown on GaAs (311)A substrates reveal a remarkable
+anisotropy: the amplitude of the measured commensurability oscillations along
+the [$\bar{2}$33] direction is about 100 times larger than along [01$\bar{1}$].
+For 2D electron systems at similar interfaces, however, we observe nearly
+isotropic oscillations, suggesting that the anomalous anisotropy is intrinsic
+to GaAs 2D holes at the (311)A interface.",0009363v1
+2000-12-10,Anisotropic scattering and quantum magnetoresistivities of a periodically modulated 2D electron gas,"We calculate the longitudinal conductivities of a two-dimensional
+noninteracting electron gas in a uniform magnetic field and a lateral electric
+or magnetic periodic modulation in one spatial direction, in the quantum
+regime. We consider the effects of the electron-impurity scattering anisotropy
+through the vertex corrections on the Kubo formula, which are calculated with
+the Bethe-Salpeter equation, in the self-consistent Born approximation. We find
+that due to the scattering anisotropy the band conductivity increases, and the
+scattering conductivities decrease and become anisotropic. Our results are in
+qualitative agreement with recent experiments.",0012165v1
+2001-02-19,Phase diagram of a random-anisotropy mixed-spin Ising model,"We investigate the phase diagram of a mixed spin-1/2--spin-1 Ising system in
+the presence of quenched disordered anisotropy. We carry out a mean-field and a
+standard self-consistent Bethe--Peierls calculation. Depending on the amount of
+disorder, there appear novel transition lines and multicritical points. Also,
+we report some connections with a percolation problem and an exact result in
+one dimension.",0102336v1
+2001-02-28,Stripe orientation in an anisotropic t-J model,"The tilt pattern of the CuO_6 octahedra in the LTT phase of the cuprate
+superconductors leads to planar anisotropies for the exchange coupling and
+hopping integrals. Here, we show that these anisotropies provide a possible
+structural mechanism for the orientation of stripes. A t_x-t_y-J_x-J_y model
+thus serves as an effective Hamiltonian to describe stripe formation and
+orientation in LTT-phase cuprates.",0102524v1
+2001-03-13,Anisotropic superconducting properties of aligned MgB2 crystallites,"Samples of aligned MgB2 crystallites have been prepared, allowing for the
+first time the direct identification of an upper critical field anisotropy
+Hc2^{ab}/Hc2^{c}= xi_{ab}/xi_{c} ~ 1.73; with xi_{o,ab} ~ 70 A, xi_{o,c} ~ 40
+A, and a mass anisotropy ratio m_{ab}/m_{c} ~ 0.3. A ferromagnetic background
+signal was identified, possibly related to the raw materials purity.",0103287v4
+2001-05-17,"Anisotropy of p states and 11B nuclear spin-lattice relaxation in (Mg,Al)B2","We calculated the nuclear spin-lattice relaxation rate in the (Mg,Al)B2
+system and found that the orbital relaxation mechanism dominates over the
+dipolar and Fermi-contact mechanisms in MgB2, whereas in AlB2 due to a smaller
+density of states and strong anisotropy of boron p orbitals the relaxation is
+completely determined by Fermi-contact interaction. The results for MgB2 are
+compared with existing experimental data, whereas our results for the doped
+alloy and AlB2 can be used in future experiments to verify the theoretical
+predictions about the electronic structure of this system.",0105356v1
+2001-05-26,Time-resolved ferromagnetic resonance in epitaxial Fe1-xCox films,"Magnetodynamics in epitaxial Fe1-xCox films on GaAs (100) are studied using
+time-resolved ferromagnetic resonance, in which the free precession of the
+magnetization after an impulsive excitation is measured using the polar Kerr
+effect. The sample is rotated with respect to the static and pulsed field
+directions, providing a complete mapping of the free energy surface and
+characteristic relaxation times. The magnetic response can be simulated with a
+simple coherent rotation model except in the immediate vicinity of switching
+fields. Bulk and surface anisotropies are identified, and unusual dynamics
+associated with the coexistence of cubic and uniaxial anisotropies are
+observed.",0105513v1
+2001-07-03,Importance of Correlation Effects on Magnetic Anisotropy in Fe and Ni,"We calculate magnetic anisotropy energy of Fe and Ni by taking into account
+the effects of strong electronic correlations, spin-orbit coupling, and
+non-collinearity of intra--atomic magnetization. The LDA+U method is used and
+its equivalence to dynamical mean--field theory in the static limit is
+emphasized. Both experimental magnitude of MAE and direction of magnetization
+are predicted correctly near U=1.9 eV, J=1.2 eV for Ni and U=1.2 eV, J=0.8 eV
+for Fe. Correlations modify the one--electron spectra which are now in better
+agreement with experiments.",0107063v1
+2001-07-05,Magnetization in quasiperiodic magnetic multilayers with biquadratic exchange and uniaxial anisotropy,"A theoretical study is made of the magnetization versus applied field curves
+of ferromagnetic/nonmagnetic multilayers constructed according to a Fibonacci
+quasiperiodic sequence. The ferromagnetic films are assumed to have uniaxial
+anisotropy and are coupled by both bilinear and biquadratic effective exchange.
+The effects of quasiperiodicity in the magnetic phases are illustrated
+numerically for Fe/Cr systems.",0107127v1
+2001-07-25,Complementary Theories of Energy Gaps in HTSC,"We examine experiments on energy gaps in high temperature superconductors
+(HTSC) in terms of experimental probes that utilize momentum, position, or
+neither. Experiments on very high quality mechanical tunnel junctions show a
+sharp energy gap with a maximum anisotropy of ~ 10%, while ultrahigh precision
+ARPES experiments show 100% anisotropy (d-wave pairing). We resolve this
+conbflict by showing that the latter result is caused by the
+momentum-projective nature of ARPES and glassy orthorhombic dopant
+correlations. The latter appear to be a universal feature of the intermediate
+phase tha is responsible for HTSC. Apparent large inconsistencies between
+position-projective STM gap data and tunnel junction data on severely
+underdoped BSCCO are also resolved.",0107531v1
+2001-07-26,Direct Investigation of Superparamagnetism in Co Nanoparticle Films,"A direct probe of superparamagnetism was used to determine the complete
+anisotropy energy distribution of Co nanoparticle films. The films were
+composed of self-assembled lattices of uniform Co nanoparticles 3 nm or 5 nm in
+diameter, and a variable temperature scanning-SQUID microscope was used to
+measure temperature-induced spontaneous magnetic noise in the samples. Accurate
+measurements of anisotropy energy distributions of small volume samples will be
+critical to magnetic optimization of nanoparticle devices and media.",0107556v1
+2001-07-30,Giant Spin Relaxation Anisotropy in Zinc-Blende Heterostructures,"Spin relaxation in-plane anisotropy is predicted for heterostructures based
+on zinc-blende semiconductors. It is shown that it manifests itself especially
+brightly if the two spin relaxation mechanisms (D'yakonov-Perel' and Rashba)
+are comparable in efficiency. It is demonstrated that for the quantum well
+grown along the [0 0 1] direction, the main axes of spin relaxation rate tensor
+are [1 1 0] and [1 -1 0].",0107599v1
+2001-08-05,Studies on the Anisotropic Properties of MgB2,"This paper presents a brief review on the reported anisotropic properties of
+MgB2, in the superconducting state (e.g. upper critical field Hc2, field
+penetration depth, coherence length, energy gap) as well as in the normal state
+(e.g., magnetoresistance, compressibility, thermal expansion). So far, the
+reported results have been obtained using aligned crystallites, c-axis oriented
+thin films and sub-millimeter crystals. Since impurity scattering affects
+directly the gap anisotropy it could be one of the main reasons for the
+different values observed in the Hc2 anisotropy ratio, ranging between 1.3 and
+2.6.",0108093v1
+2001-08-09,Magnetic Anisotropy Variations and Non-Equilibrium Tunneling in a Cobalt Nanoparticle,"We present detailed measurements of the discrete electron-tunneling level
+spectrum within nanometer-scale cobalt particles as a function of magnetic
+field and gate voltage, in this way probing individual quantum many-body
+eigenstates inside ferromagnetic samples. Variations among the observed levels
+indicate that different quantum states within one particle are subject to
+different magnetic anisotropy energies. Gate-voltage studies demonstrate that
+the low-energy tunneling spectrum is affected dramatically by the presence of
+non-equilibrium spin excitations.",0108166v1
+2001-11-12,Quadratic transverse anisotropy term due to dislocations in Mn12-Ac directly obtained by EPR spectroscopy,"High-Sensitivity Electron Paramagnetic Resonance experiments have been
+carried out in fresh and stressed Mn12-Acetate single crystals for frequencies
+ranging from 40 GHz up to 110 GHz. The high number of crystal dislocations
+formed in the stressing process introduces a E(S_x^2-S_y^2) transverse
+anisotropy term in the spin hamiltonian. From the behaviour of the resonant
+absorptions on the applied transverse magnetic field we have obtained an
+average value for E = 22 mK, corresponding to a concentration of dislocations
+per unit cell of c = 10^-3.",0111208v1
+2001-11-23,Optical responses through dilute anisotropic composites: Numerical calculations via Green's-function formalism,"We investigate the linear and nonlinear optical responses of dilute
+anisotropic networks using the Green's-function formalism (GFF)[Gu Y et al.
+1999 Phys. Rev. B 59 12847]. For the different applied fields, numerical
+calculations indicate that a large third order nonlinear enhancement and a
+broad infrared absorption arise from the geometric anisotropy. It is also shown
+the overlap and separation between the absorption peak and nonlinear
+enhancement peak when the applied field is parallel, perpendicular to the
+anisotropy respectively. In terms of the inverse participation ratios (IPR)
+with q=2 and spectral distribution of optical responses, the results can be
+understood.",0111459v1
+2001-12-03,Multiple Field-Induced Phase Transitions in a Geometrically-Frustrated Dipolar Magnet - Gd2Ti2O7,"Field-driven phase transitions generally arise from competition between
+Zeeman energy and exchange or crystal-field anisotropy.
+  Here we present the phase diagram of a frustrated pyrochlore magnet Gd2Ti2O7,
+where crystal field splitting is small compared to the dipolar energy. We find
+good agreement between zero-temperature critical fields and those obtained from
+a mean-field model. Here, dipolar interactions couple real-space and
+spin-space, so the transitions in Gd2Ti2O7 arise from field-induced
+""cooperative anisotropy"" reflecting the broken spatial symmetries of the
+pyrochlore lattice.",0112022v1
+2002-01-15,Rigorous Bounds to Retarded Learning,"We show that the lower bound to the critical fraction of data needed to infer
+(learn) the orientation of the anisotropy axis of a probability distribution,
+determined by Herschkowitz and Opper [Phys.Rev.Lett. 86, 2174 (2001)], is not
+always valid. If there is some structure in the data along the anisotropy axis,
+their analysis is incorrect, and learning is possible with much less data
+points.",0201256v1
+2002-03-14,Modeling exchange bias microscopically,"Exchange bias is a horizontal shift of the hysteresis loop observed for a
+ferromagnetic layer in contact with an antiferromagnetic layer. Since exchange
+bias is related to the spin structure of the antiferromagnet, for its
+fundamental understanding a detailed knowledge of the physics of the
+antiferromagnetic layer is inevitable. A model is investigated where domains
+are formed in the volume of the AFM stabilized by dilution. These domains
+become frozen during the initial cooling procedure carrying a remanent net
+magnetization which causes and controls exchange bias. Varying the anisotropy
+of the antiferromagnet we find a nontrivial dependence of the exchange bias on
+the anisotropy of the antiferromagnet.",0203297v2
+2002-04-01,Ground-State Phase Diagram of Frustrated Antiferromagnetic S=1 Chain with Uniaxial Single-Ion-Type Anisotropy,"The ground-state phase diagram of a frustrated S=1 Heisenberg spin chain with
+uniaxial single-ion-type anisotropy is studied using the infinite-system
+density-matrix renormalization-group method. Particular attention is paid to
+""chiral"" phases, in which the long-range order parameter is a vector chirality.
+It is found that, in addition to the Haldane, large-D (LD), and double-Haldane
+phases, the phase diagram includes three different chiral phases, i.e., the
+gapless chiral, chiral-Haldane, and chiral-LD phases. These chiral phases are
+distinguished from each other by the energy gap and the string long-range
+order.",0204020v1
+2002-04-02,Effects of La substitution on superconducting state of CeCoIn5,"We report effects of La substitution on superconducting state of heavy
+fermion superconductor CeCoIn5, as seen in transport and magnetization
+measurements. As opposed to the case of conventional superconductors, pair
+breaking by nonmagnetic La results in depression of Tc and indicates strong gap
+anisotropy. Upper critical field Hc2 values decrease with increased La
+concentration, but the critical field anisotropy, gamma=Hc2(a)/Hc2(c), does not
+change in the Ce_{1-x}La_xCoIn5 (x=0-0.15). The electronic system is in the
+clean limit for all values of x.",0204059v1
+2002-04-14,Raman scattering through surfaces having biaxial symmetry,"Magnetic Raman scattering in two-leg spin ladder materials and the
+relationship between the anisotropic exchange integrals are analyzed by P. J.
+Freitas and R. R. P. Singh in Phys. Rev. B, {\bf 62}, 14113 (2000). The angular
+dependence of the two-magnon scattering is shown to provide information for the
+magnetic anisotropy in the Sr_14Cu_24O_41 and La_6Ca_8Cu_24O_41 compounds. We
+point out that the experimental results of polarized Raman measurements at
+arbitrary angles with respect to the crystal axes have to be corrected for the
+light ellipticity induced inside the optically anisotropic crystals. We refer
+quantitatively to the case of Sr_14Cu_24O_41 and discuss potential implications
+for spectroscopic studies in other materials with strong anisotropy.",0204312v1
+2002-06-15,Effect of a Staggered Magnetic Field on the S=1 Haldane Chain with Single-ion Anisotropy,"We analyze the gaps in the excitation spectrum of a Haldane chain with
+single-ion anisotropy in a staggered field. We show that the gap along the
+direction of the field increases at a faster rate than the others, while its
+spectral weight decreases, being transferred to a two-magnon continuum.",0206288v1
+2002-07-02,Internal localized eigenmodes on spin discrete breathers in antiferromagnetic chains with on-site easy axis anisotropy,"We investigate internal localized eigenmodes of the linearized equation
+around spin discrete breathers in 1D antiferromagnets with on-site easy axis
+anisotropy. The threshold of occurrence of the internal localized eigenmodes
+has a typical structure in parameter space depending on the frequency of the
+spin discrete breather. We also performed molecular dynamics simulation in
+order to show the validity of our linear analysis.",0207053v1
+2002-07-19,Nonlinear Mechanical Response of DNA due to Anisotropic Bending Elasticity,"The response of a short DNA segment to bending is studied, taking into
+account the anisotropy in the bending rigidities caused by the double-helical
+structure. It is shown that the anisotropy introduces an effective nonlinear
+twist-bend coupling that can lead to the formation of kinks and modulations in
+the curvature and/or in the twist, depending on the values of the elastic
+constants and the imposed deflection angle. The typical wavelength for the
+modulations, or the distance between the neighboring kinks is found to be set
+by half of the DNA pitch.",0207477v1
+2002-07-19,"Conduction Anisotropy, Hall Effect, and Magnetoresistance of (TMTSF)2ReO4 at High Temperatures","We investigated the transport properties of the quasi one-dimensional organic
+metal (TMTSF)2ReO4 above the anion-ordering metal-insulator transition (T_{AO}
+\approx 180K). The pronounced conductivity anisotropy, a small and smoothly
+temperature dependent Hall effect, and a small, positive and temperature
+dependent magnetoresistance are analyzed within the existing Fermi-liquid and
+non-Fermi liquid models. We propose that the transport properties of quasi
+one-dimensional Bechgaard salts at high temperatures can be described within
+the Fermi liquid description.",0207479v2
+2002-07-28,Anisotropy of Mott-Hubbard gap transitions due to spin and orbital ordering in LaVO3 and YVO3,"Anisotropic optical spectra coupled with antiferromagnetic spin ordering (SO)
+and orbital ordering (OO) have been investigated for single crystals of
+LaVO_{3} and YVO_{3}. The orbital-dependent Mott-Hubbard gap transitions are
+observed around 2 eV. The transitions composed of the two peaks show distinct
+anisotropy and selection rules, reflecting the respective SO and OO patterns.
+The temperature dependence of the anisotropic transitions clearly indicates the
+SO/OO correlation and the evolution of the order parameters.",0207664v1
+2002-09-11,Magnetic Anisotropy in La_0.8Sr_0.2MnO_3: Electron Spin Resonance,"We report on Ferromagnetic-Resonance experiments in a single crystal of
+La_0.8Sr_0.2MnO_3 in the temperature range from 4 to 300 K. The observed
+anisotropy of the resonance line changes on crossing the transition from the
+orthorhombic O-phase to the rhombohedral R-phase at T~100 K and indicates a
+reorientation of the spins at about 130 K.",0209257v1
+2002-10-04,The Effects of the Misfit Structure on Thermoelectric Properties of Bi2-xPbxSr2Co2Oy Single Crystals,"In-plane anisotropy of the resistivity and thermopower was measured for
+single crystal Bi2-xPbxSr2Co2Oy. There is large in-plane anisotropy, which is
+attributed to the anisotropic pseudogap formation due to the different crystal
+symmetry between the square Bi2Sr2O4 layer and the triangular CuO2 layer. The
+magnitude of the thermopower both along a- and b-axis direction increases with
+Pb doping from x=0 to 0.4, where we observe discontinuous shrink of b-axis
+length. We attribute this to the enhancement of the misfitness. Thus, we can
+improve the thermoelectric properties by tuning the misfitness.",0210087v1
+2002-10-08,Coulomb Correlations and Magnetic Anisotropy in ordered $L1_0$ CoPt and FePt alloys,"We present results of the magneto-crystalline anisotropy energy (MAE)
+calculations for chemically ordered $L1_0$ CoPt and FePt alloys taking into
+account the effects of strong electronic correlations and spin-orbit coupling.
+The local spin density + Hubbard U approximation (LSDA+U) is shown to provide a
+consistent picture of the magnetic ground state properties when intra-atomic
+Coulomb correlations are included for both 3$d$ and 5$d$ elements. Our results
+demonstrate significant and complex contribution of correlation effects to
+large MAE of these material.",0210157v2
+2002-11-07,Piezoresistivity and conductance anisotropy of tunneling-percolating systems,"Percolating networks based on interparticle tunneling conduction are shown to
+yield a logarithmic divergent piezoresistive response close to the critical
+point as long as the electrical conductivity becomes nonuniversal. At the same
+time, the piezoresistivity or, equivalently, the conductivity anisotropy
+exponent $\lambda$ remains universal also when the conductive exponent is not,
+suggesting a purely geometric origin of $\lambda$. We discuss our results in
+relation to the nature of transport for a variety of materials such as
+carbon-black--polymer composites and RuO_2-glass systems which show
+nonuniversal transport properties and coexistence between tunneling and
+percolating behaviors.",0211133v2
+2002-11-12,Electronic structure and magnetic anisotropy of the [Co_4(hmp)_4(CH_3OH)_4Cl_4] molecule,"Accurate density-functional based calculations have been performed on the
+Co_4(hmp)_4(CH_3OH)_4Cl_4 molecular magnet where hmp is deprotonated
+hydroxymethyl pyridine. In addition to the experimentally observed staggered
+geometry, we identify two isomers, referred to as eclipsed and
+half-staggered/half-eclipsed, that are reasonably low in energy. Our
+calculations show that the magnetic anisotropy is strongly dependent on the
+pyridine-pyridine separation and that the three structures exhibit easy axis,
+easy plane and triaxial behavior. Other effects such as partial reprotonation
+of the hmp is considered.",0211221v1
+2002-11-29,Anisotropic Magnetoresistance in GaMnAs films,"The magnetoresistance in a series of Ga1-xMnxAs samples with 0.2 =< x =< 0.8
+have been measured for three mutually orthogonal orientations of the external
+magnetic field. The anisotropy magnetoresistance decreases with increasing of
+the Mn content, which means that the magnetic disorder or defects scattering
+increases with increasing of Mn content. And also the magneto-crystalline
+anisotropy increases with increasing of Mn concentration.",0211697v1
+2002-12-03,Thermal stability of coupled ferromagnetic and superparamagnetic particles,"We consider a single-domain ferromagnetic particle with uniaxial anisotropy
+coupled to a single-domain soft ferromagnetic particle (superparamagnetic
+particle). The problem of thermally agitated magnetization reversal in this
+case can be reduced to the random magnetization dynamics of the first particle
+with an effectively larger anisotropy field. The magnetic external field is
+also altered in a manner that depends on the sign of the coupling and can be
+either enhanced or suppressed.",0212041v1
+2002-12-16,Anisotropy parameters of superconducting MgB$_2$,"Data on macroscopic superconducting anisotropy of MgB$_2$ are reviewed. The
+data are described within a weak coupling two-gaps anisotropic s-wave model of
+superconductivity. The calculated ratio of the upper critical fields
+$\gamma_H=H_{c2,ab}/H_{c2,c}$ increases with decreasing temperature in
+agreement with available data, whereas the calculated ratio of London
+penetration depths $\gamma_{\lambda}=\lambda_c/\lambda_{ab}$ decreases to reach
+$\approx 1.1$ at T=0. Possible macroscopic consequences of
+$\gamma_{\lambda}\ne\gamma_H$ are discussed.",0212383v1
+2002-12-17,"Comment on ""First-principles calculation of the superconducting transition in MgB2 within the anisotropic Eliashberg formalism""","Choi et al. [Phys. Rev. B 66, 020513 (2002)] recently presented first
+principles calculations of the electron-phonon coupling and superconductivity
+in MgB2, emphasizing the importance of anisotropy and anharmonicity. We point
+out that (1) variation of the superconducting gap inside the sigma- or the
+pi-bands can hardly be observed in real samples, and (2) taking the anisotropy
+of the Coulomb repulsion into account influences the size of the small gap,
+Delta_pi.",0212417v3
+2003-03-20,On a dual model for 5f electrons,"We study the effect of intra-atomic correlations on anisotropies of hopping
+of 5f electrons. It is shown that they may considerably enhance these
+anisotropies to the extend that electrons in some of the 5f orbitals remain
+localized. This provide a microscopic basis for a previously made assumption
+that some of the 5f electrons must be partially localized when Fermi surfaces
+and effective masses of the component are calculated. Calculations are
+performed on two- and three-sites clusters. They include phase diagrams in the
+presence and absence of an external magnetic field as function of anisotropic
+hopping.",0303414v1
+2003-05-01,"Reply to the comment on the paper ""Thermodynamics of two-dimensional magneto nanoparticles (P. Vargas, D. Altbir, M.Knobel and D. Laroze)"" by H. Buettner and Yu. Gaididei","It is shown that there is bi-stability in a two dimensional system consisting
+of non interacting magnetic nanoparticles with equal uniaxial anisotropies. It
+is also shown that bi-stability still remains in three dimensions. The only
+consideration is that the applied magnetic field has to be perpendicular to the
+anisotropy axis.",0305023v1
+2003-06-24,Doping dependence of the gap anisotropy in LCCO studied by millimeter-wave spectroscopy,"We measure the penetration depth of optimally doped and underdoped
+La2-xCexCuO4 in the millimeter frequency domain (4 - 7 cm-1) and for
+temperatures 2 K < T < 300 K. The penetration depth as function of temperature
+reveals significant changes on electron doping. It shows quadratic temperature
+dependence in underdoped samples, but increases almost exponentially at optimal
+doping. Significant changes in the gap anisotropy (or even in the gap symmetry)
+may account for this transition.",0306606v1
+2003-09-23,On the Field Dependence of the Interface Energy in Af/FM Bilayers,"In the investigations of antiferromagnetic (AF)/ ferromagnetic (FM) bilayer
+samples, often distinct experimental techniques yield different values for the
+measured exchange anisotropy field (HE). We propose that the observed
+discrepancy may be accounted in part by the dependence of the unidirectional
+anisotropy with the value of the external applied field (h). Using a simple
+microscopic model for representing the AF/FM interface, which incorporates the
+effect of interface roughness, we show that the interface energy between the AF
+and FM layer indeed varies with h, as recently observed in anisotropic
+magnetoresistance measurements, lending support to our proposal.",0309535v1
+2003-12-18,Controlled normal and inverse magnetoresistance and current-driven magnetization switching in magnetic nanopillars,"Combining pairs of ferromagnetic metals with different signs of scattering
+anisotropies, let us independently invert the magnetoresistance and the
+direction of current-driven switching in
+ferromagnetic/non-magnetic/ferromagnetic metal nanopillars. We show all four
+combinations of normal and inverse behaviors, at both room temperature and
+4.2K. In all cases studied, the direction of switching is set by the net
+scattering anisotropy of the fixed (polarizing) ferromagnet. We provide simple
+arguments for what we see.",0312475v1
+2004-02-14,Depolarization of backscattered linearly polarized light,"We formulate a quantitative description of backscattered linearly polarized
+light using an extended photon diffusion formalism taking explicitly into
+account the scattering anisotropy parameter g of the medium. From diffusing
+wave spectroscopy measurements the characteristic depolarization length for
+linearly polarized light is deduced. We investigate the dependance of this
+length on the scattering anisotropy parameter g spanning an extended range from
+-1 (backscattering) to 1 (forward scattering). Good agreement is found with
+Monte Carlo simulations of multiply scattered light.",0402391v1
+2004-02-16,Triplet superconductivity vs. easy-plane ferromagnetism in a 1D itinerant electron system with transverse spin anisotropy,"In this paper we study the ground state phase diagram of a one-dimensional
+$t-U-J$ model, at half-filling. In the large-bandwidth limit and for
+ferromagnetic exchange with easy-plane anisotropy, a phase with gapless charge
+and massive spin excitations, characterized by the coexistence of triplet
+superconducting and spin density wave instabilities is realized in the ground
+state. With reduction of the bandwidth, a transition into an insulating phase
+showing properties of the spin-1/2 XY model takes place.",0402405v1
+2004-02-25,Spin Dynamics of a Canted Antiferromagnet in a Magnetic Field,"The spin dynamics of a canted antiferromagnet with a quadratic spin-wave
+dispersion near $\vq =0$ is shown to possess a unique signature. When the
+anisotropy gap is negligible, the spin-wave stiffness $\dsw (\vq, B) =
+(\omega_{\vq}-B)/q^2$ depends on whether the limit of zero field or zero
+wavevector is taken first. Consequently, $\dsw $ is a strong function of
+magnetic field at a fixed wavevector. Even in the presence of a sizeable
+anisotropy gap, the field dependence of both $\dsw $ and the gap energy
+distinguishes a canted antiferromagnet from a phase-separated mixture
+containing both ferromagnetic and antiferromagnetic regions.",0402633v2
+2004-03-16,Anisotropy-induced ordering in the quantum J1-J2 antiferromagnet,"We study the effect of spin anisotropies on a frustrated quantum
+antiferromagnet using the J_1-J_2^{XXZ} model on the square lattice. The T=0
+and finite-T phase diagrams of this model are obtained utilizing spin-wave
+theory, exact diagonalization, and quantum Monte Carlo. We find that
+anisotropic frustration tends to stabilize XY- and Ising-like ordered phases,
+while the disordered spin-liquid phase is restricted to a small region of the
+phase diagram. The ordered phases are separated by first-order transitions and
+exhibit a non-trivial reentrance phenomenon.",0403375v1
+2004-03-23,Field dependence of the zero energy density of states around vortices in an anisotropic gap superconductor,"It is shown theoretically that the Sommerfeld coefficient $\gamma(B)$ in the
+mixed state contains useful information on the gap topology in a
+superconductor. We accurately evaluate $\gamma(B)$ against magnetic induction
+$B$ by using microscopic quasi-classical theory. The linear portion in
+{$\gamma(\propto B)$} relative to $B_{\rm c2}$ and its slope in low field
+faithfully corresponds to the gap anisotropy, so that we can distinguish the
+nodal gap and the anisotropic full gap, and estimate the magnitude of the gap
+anisotropy.",0403589v1
+2004-04-03,"Pinning a Domain Wall in (Ga,Mn)As with Focused Ion Beam Lithography","We utilize a focused beam of Ga+ ions to define magnetization pinning sites
+in a ferromagnetic epilayer of (Ga,Mn)As. The nonmagnetic defects locally
+increase the magneto-crystalline anisotropy energies, by which a domain wall is
+pinned at a given position. We demonstrate techniques for manipulating domain
+walls at these pinning sites as probed with the giant planar Hall effect
+(GPHE). By varying the magnetic field angle relative to the crystal axes, an
+upper limit is placed on the local effective anisotropy energy.",0404068v1
+2004-04-14,Evidence of gap anisotropy in superconducting YNi2B2C using directional point contact spectroscopy,"We present a study of the anisotropy in the superconducting energy gap in a
+single crystal of YNi2B2C (Tc~14.6K) using directional point contact
+spectroscopy. The superconducting energy gap at 2.7K, when measured for I||c,
+is 4.5 times larger than that for I||a. The energy gaps in the two directions
+also have different temperature dependences. Our results support a scenario
+with s+g like symmetry.",0404322v1
+2004-04-16,Changes in magnetic scattering anisotropy at a ferromagnetic/superconducting interface,"We show that some metals and alloys (X = Cu, Ag, FeMn, or Cu and Ag combined
+with each other), sputtered between ferromagnetic Co and superconducting Nb,
+produce no change in current-perpendicular-to-plane magnetoresistance (CPP-MR)
+in a carefully designed CPP-spin-valve. In contrast, other metals (Ru or Au) or
+combinations (Cu or Ag combined with Au, Ru, or FeMn) change the CPP-MR, in
+some cases even reversing its sign. We ascribe these changes to activation of
+magnetic scattering anisotropies at a ferromagnetic/superconducting interface,
+apparently by strong spin-flipping between the Co and Nb layers.",0404396v1
+2004-04-18,Anisotropy of superconductivity of as-grown MgB$_2$ thin films by molecular beam epitaxy,"Superconducting thin films of magnesium diboride (MgB$_2$) were prepared on
+MgO (001) substrate by a molecular beam epitaxy (MBE) method with the
+co-evaporation conditions of low deposition rate in ultra-high vacuum. The
+structural and physical properties of the films were studied by RHEED, XRD,
+XPS, resistivity and magnetization measurements.All films demonstrated
+superconductivity without use of any post-annealing process.The highest {\it
+T}$_{c,onset}$ determined by resistivity measurement was about 33K in the
+present samples.Anisotropic superconducting properties were evaluated by the
+resistivity and magnetic measurements.We will discuss the anisotropy of
+superconductivity for as-grown MgB$_2$ thin films.",0404415v1
+2004-05-01,Anisotropy of Resonant Inelastic X-Ray Scattering at the K Edge of Si:Theoretical Analysis,"We investigate theoretically the resonant inelastic x-ray scattering (RIXS)
+at the $K$ edge of Si on the basis of an ab initio calculation. We calculate
+the RIXS spectra with systematically varying transfered-momenta,
+incident-photon energy and incident-photon polarization. We confirm the
+anisotropy of the experimental spectra by Y. Ma {\it et al}. (Phys. Rev. Lett.
+74, 478 (1995)), providing a quantitative explanation of the spectra.",0405009v4
+2004-05-24,Determination of the magnetic anisotropy axes of single-molecule magnets,"Simple methods are presented allowing the determination of the magnetic
+anisotropy axes of a crystal of a single-molecule magnet (SMM). These methods
+are used to determine an upper bound of the easy axis tilts in a standard
+Mn12-Ac crystal. The values obtained in the present study are significately
+smaller than those reported in recent high frequency electron paramagnetic
+resonance (HF-EPR) studies which suggest distributions of hard-axes tilts.",0405565v1
+2004-06-09,Anisotropy in double negative permittivity and permeability materials or left-handed materials : the effect on guided wave propagating electromagnetic fields,"Effect of anisotropy in the physical tensor description of the negative index
+of refraction material (left-handed material, LHM) acting as a substrate is
+found on the electromagnetic field distributions. Field distributions are
+provided in the GHz region in the cross-section of the uniform microstrip
+guided wave structure. It is found from ab initio Green's function calculations
+that modifying the tensor can allow control because the wave changes
+volumetrically, or switches from volumetric to surface, in its distribution of
+fields. Comparison is made of the LHM results to ordinary right-handed material
+(RHM) acting as a substrate.",0406219v2
+2004-07-09,Magnetic order in lightly doped La_{2-x}Sr_{x}CuO_{4},"We study long wavelength magnetic excitations in lightly doped
+La_{2-x}Sr_{x}CuO_{4} (x < 0.03) detwinned crystals. The lowest energy magnetic
+anisotropy induced gap can be understood in terms of the antisymmetric spin
+interaction inside the antiferromagnetic (AF) phase. The second magnetic
+resonace, analyzed in terms of in-plane spin anisotropy, shows unconventional
+behavior within the AF state and led to the discovery of collective spin
+excitations pertaining to a field induced magnetically ordered state. This
+state persists in a 9 T field to more than 100 K above the N\'{e}el temperature
+in x = 0.01.",0407248v1
+2004-08-13,Finite lattice size effect in the ground state phase diagram of quasi-two-dimensional magnetic dipolar dots array with perpendicular anisotropy,"A prototype Hamiltonian for the generic patterned magnetic structures, of
+dipolar interaction with perpendicular anisotropy, is investigated within the
+finite-size framework by Landau-Lifshift-Gilbert classical spin dynamics.
+Modifications on the ground state phase diagram are discussed with an emphasis
+on the disappearance of continuous degeneracy in the ground state of in-plane
+phase due to the finite lattice size effect. The symmetry-governed ground state
+evolution upon the lattice size increase provides a critical insight into the
+systematic transition to the infinite extreme.",0408324v1
+2004-09-01,Momentum space anisotropy in doped Mott insulators,"We study the single hole tt't''J-model numerically to address the momentum
+space anisotropy found in doped Mott insulators. A simple two band picture to
+understand how the doped hole is screened by the spin background in states of
+different momenta is proposed. In this picture, the disparity between the nodal
+and antinodal regions, observed by experiments in the underdoped cuprate
+superconductors, follows from local energetic considerations and amounts to the
+distinction between well defined quasiparticle behavior and spin-charge
+separation related phenomenology.",0409002v3
+2004-10-21,"Implications of the isotope effects on the magnetization, magnetic torque and susceptibility","We analyze the magnetization, magnetic torque and susceptibility data of
+La2-xSrxCu(16,18)O4 and YBa2(63,65)CuO7-x near Tc in terms of the universal
+3D-XY scaling relations. It is shown that the isotope effect on Tc mirrors that
+on the anisotropy. Invoking the generic behavior of the anisotropy the doping
+dependence of the isotope effects on the critical properties, including Tc,
+correlation lengths and magnetic penetration depths are traced back to a change
+of the mobile carrier concentration.",0410547v1
+2004-10-28,Complex shape evolution of electromigration-driven single-layer islands,"The shape evolution of two-dimensional islands through periphery diffusion
+biased by an electromigration force is studied numerically using a continuum
+approach. We show that the introduction of crystal anisotropy in the mobility
+of edge atoms induces a rich variety of migration modes, which include
+oscillatory and irregular behavior. A phase diagram in the plane of anisotropy
+strength and island size is constructed. The oscillatory motion can be
+understood in terms of stable facets which develop on one side of the island
+and which the island then slides past. The facet orientations are determined
+analytically.",0410745v2
+2004-11-11,Anisotropic Diamagnetic Response in Type-II Superconductors with Gap and Fermi-Surface Anisotropies,"Effects of anisotropic gap structures on a diamagnetic response are
+investigated in order to demonstrate that the field-angle-resolved
+magnetization ($M_L(\chi)$) measurement can be used as a spectroscopic method
+to detect gap structures. Our microscopic calculation based on the
+quasiclassical Eilenberger formalism reveals that $M_L(\chi)$ in a
+superconductor with four-fold gap displays a four-fold oscillation reflecting
+the gap and Fermi surface anisotropies, and the sign of this oscillation
+changes at a field between $H_{c1}$ and $H_{c2}$. As a prototype of
+unconventional superconductors, magnetization data for borocarbides are also
+discussed.",0411290v2
+2004-11-25,Magnetoresistance in metals with embedded magnetic nano-clusters,"We propose a kinetic theory of transport in metals embedded with
+ferromagnetic nanoclusters, describing the dependence of the form of
+magnetoresistance on anisotropy characteristics of the ensemble of clusters and
+the influence of the electron spin depolarisation by clusters. We note that
+this effect is strongest when all the clusters have the same intrinsic
+easy-axis anisotropy.",0411655v2
+2004-12-15,Effects of edges in spin-1/2 bond-alternating Heisenberg chains: Matrix-product variational approach,"We make a matrix-product variational approach to spin-1/2
+ferromagnetic-antiferromagnetic bond-alternating chains with anisotropy on
+their ferromagnetic bonds, especially under the open boundary condition. The
+rich phase diagram containing the Haldane, large-D, and two types of Neel
+phases is well reproduced with only two variational parameters. The on-bond
+anisotropy has a significant effect on the ferromagnetic coupling between
+neighboring spins and induces novel edge states peculiar to spin-1/2 chains.",0412390v1
+2004-12-17,Hysteresis loops of magnetic thin films with perpendicular anisotropy,"We model the magnetization of quasi two-dimensional systems with easy
+perpendicular (z-)axis anisotropy upon change of external magnetic field along
+z. The model is derived from the Landau-Lifshitz-Gilbert equation for
+magnetization evolution, written in closed form in terms of the z component of
+the magnetization only. The model includes--in addition to the external
+field--magnetic exchange, dipolar interactions and structural disorder. The
+phase diagram in the disorder/interaction strength plane is presented, and the
+different qualitative regimes are analyzed. The results compare very well with
+observed experimental hysteresis loops and spatial magnetization patterns, as
+for instance for the case of Co-Pt multilayers.",0412461v1
+2005-02-12,Does Optical Anisotropy Lead to Negative Refraction at an Interface?,"This is a comment inspired by recently published results [Y. Zhang et al.,
+Phys. Rev. Lett. 91, 157404 (2003)] that introduced the name ""amphoteric
+refraction"" for the fact that at the interface with an optically anisotropic
+material there can be a range of incidence angles for which the component of
+the Poynting vector parallel to the interface changes sign upon refraction. The
+latter effect is a well-known consequence of optical anisotropy, but it was
+described as a new negative refraction phenomenon that can be put in the same
+class as the negative refraction observed at an interface with a left-handed
+material with negative refractive index.",0502308v2
+2005-02-24,Pressure effects on the superconducting properties of YBa_2Cu_4O_8,"Measurements of the magnetization under high hydrostatic pressure (up to 10.2
+kbar) in YBa_2Cu_4O_8 were carried out. From the scaling analysis of the
+magnetization data the pressure induced shifts of the transition temperature
+T_c, the volume V and the anisotropy \gamma have been obtained. It was shown
+that the pressure induced relative shift of T_c mirrors essentially that of the
+anisotropy. This observation uncovers a novel generic property of anisotropic
+type II superconductors, that inexistent in the isotropic case.",0502576v1
+2005-05-10,"Nanomechanical Measurements of Magnetostriction and Magnetic Anisotropy in (Ga,Mn)As","A (Ga,Mn)As nanoelectromechanical resonator is used to obtain the first
+direct measurement of magnetostriction in a dilute magnetic semiconductor.
+Field-dependent magnetoelastic stress induces shifts in resonance frequency
+that can be discerned with a high resolution electromechanical transduction
+scheme. By monitoring the field dependence, the magnetostriction and anisotropy
+field constants can be simultaneously mapped over a wide range of temperatures.
+These results, when compared with theoretical predictions, appear to provide
+insight into a unique form of magnetoelastic behavior mediated by holes.",0505222v1
+2005-06-10,Spin-charge-orbital ordering on triangle-based lattices,"We investigate the ground-state property of an e_g-orbital Hubbard model at
+quarter filling on a zigzag chain by exploiting the density matrix
+renormalization group method. When two orbitals are degenerate, the zigzag
+chain is decoupled to a doble-chain spin system to suppress the spin
+frustration due to the spatial anisotropy of the occupied orbital. On the other
+hand, when the level splitting is increased and the orbital anisotropy
+disappears, a characteristic change in the spin incommnsurability is observed
+due to the revival of the spin frustration.",0506242v1
+2005-06-15,Enhanced Magnetic Anisotropy of Mn12-acetate,"Thin films of the Single Molecule Magnet (Mn12-acetate) have been fabricated
+on a Si-substrate by the Dip-and-Dry method, a simple and robust technique.
+Atomic force microscopy and X-ray photoelectron spectroscopy characterizations
+reveal that homogeneous, thin films of a few molecular layers with smoothness
+at the molecular level are deposited. Significant changes in magnetic
+properties of Mn12-acetate exposed to the same solvent were observed in
+zero-field-cooled and field-cooled magnetization, as well as ac-susceptibility
+measurements. The blocking temperature was found to increase to TB > 10 K at
+low magnetic fields, indicating an enhanced magnetic anisotropy.",0506378v1
+2005-06-16,Orbital order and spin-orbit coupling in BaVS3,"The correlated 3d sulphide BaVS3 undergoes a sequence of three symmetry
+breaking transitions which are reflected in the temperature dependence of the
+magnetic susceptibility, and its anisotropy. We introduce a microscopic model
+based on the coexistence of wide band a(1g) and localized e(g) d-electrons, and
+give the classification of the order parameters under the double space group
+and time reversal symmetries. Allowing for the relativistic spin-orbit
+coupling, the d-shell multipoles acquire a mixed spin-orbital character. It
+follows that orbital ordering is accompanied by a change in the susceptibility
+anisotropy",0506409v1
+2005-06-19,Anisotropic Hubbard model on a triangular lattice -- spin dynamics in Ho Mn O_3,"The recent neutron-scattering data for spin-wave dispersion in $\rm Ho Mn
+O_3$ are well described by an anisotropic Hubbard model on a triangular lattice
+with a planar (XY) spin anisotropy. Best fit indicates that magnetic
+excitations in $\rm Ho Mn O_3$ correspond to the strong-coupling limit $U/t >
+\sim 15$, with planar exchange energy $J=4t^2/U \simeq 2.5$meV and planar
+anisotropy $\Delta U \simeq 0.35$meV.",0506475v3
+2005-07-06,Orientational symmetry-breaking correlations in square lattice t-J model,"We study a tendency to orientational symmetry breaking of the square lattice
+t-J model by applying the exact diagonalization technique. We introduce a small
+external anisotropy to t and J, and calculate the induced anisotropy of
+hole-hole correlations as a response. It is found that the response is strongly
+enhanced for particular band parameters, meaning that the system has a strong
+tendency to orientational symmetry breaking. The analysis of the momentum
+distribution function indicates that the correlation develops when the Fermi
+surface is close to (pi,0) and (0,pi). Some properties of high-Tc cuprates
+previously attributed to stripes can also be understood from orientational
+symmetry breaking alone.",0507146v1
+2005-08-15,Opening of pseudogaps due to superconducting critical fluctuations in quasi-two dimensions,"We examine the role of the anisotropy of superconducting thermal critical
+fluctuations in the opening of pseudogaps in quasi-two dimensions. When the
+anisotropy of coherence or correlation lengths of the fluctuations is large
+enough and critical temperatures T_c are high enough, the energy dependence of
+the selfenergy deviates from that of Landau's normal Fermi liquid in critical
+regions; its imaginary part has no minimum at the chemical potential. Prominent
+pseudogaps open in such a non-Fermi liquid phase. Pseudogaps must be absent or
+subtle in quasi-two dimensional superconductors with low T_c and almost
+isotropic three dimensional superconductors.",0508344v1
+2005-08-15,Electronic structure and anisotropic transport properties in hexagonal YPtIn and LuAgGe ternary compounds,"We present anisotropic, zero applied magnetic field, temperature dependent
+resistivity measurements on hexagonal, non-magnetic, YPtIn and LuAgGe single
+crystals. For these materials the in-plane resistivity, $\rho_{ab}$, is
+significantly higher than the $c$ - axis one, $\rho_c$, with $\rho_{ab}/\rho_c
+\approx 1.4$ for YPtIn and $\approx 4.2 - 4.7$ for LuAgGe. The connection
+between the electronic structure and the anisotropic transport properties is
+discussed using density functional calculations that link the observed
+anisotropy with a specific shape of Fermi surface and anisotropy of the Fermi
+velocities.",0508346v1
+2005-09-29,Comment to: Correlation Between Superfluid Density and T_{c} of Underdoped YBa2Cu3O6+x Near the Superconductor-Insulator Transition,"Zuev et al. reported measurements of the in-plane magnetic penetration depth
+of supposedly underdoped films of YBa2Cu3O6+x, with Tc from 6 to 50 K. They
+argue that their data is inconsistent with a linear relationship between Tc and
+the inversw of the T=0 in-plane penetration depth squared, as expected for a
+two dimensional quantum superconductor to insulator (2D-QSI) transition where
+Tc vanishes and the anisotropy diverges. It is shown that the data of Zuev et
+al. do not fall onto the regime where the linear relationship applies, because
+the observed reduction of Tc is not associated with an increase of the
+anisotropy.",0509768v1
+2005-10-07,Perpendicular magnetic anisotropy in nanoclusters caused by surface segregation and shape,"The growth of binary alloy clusters on a weakly interacting substrate through
+codeposition of two atomic species is studied by kinetic Monte Carlo
+simulation. Our model describes salient features of CoPt$_3$-nanoclusters, as
+obtained recently by the molecular-beam epitaxy technique. The clusters display
+perpendicular magnetic anisotropy (PMA) in a temperature window of growth
+favorable for applications. This temperature window is found to arise from the
+interplay of Pt surface segregation and aspect ratio for cluster shapes.
+Conclusions are drawn how to optimize growth parameters with respect to PMA.",0510196v1
+2005-11-22,Influence of anisotropic next-nearest-neighbor hopping on diagonal charge-striped phases,"We consider the model of strongly-correlated system of electrons described by
+an extended Falicov-Kimball Hamiltonian where the stability of some axial and
+diagonal striped phases was proved. Introducing a next-nearest-neighbor
+hopping, small enough not to destroy the striped structure, we examine
+rigorously how the presence of the next-nearest-neighbor hopping anisotropy
+reduces the $\pi/2$-rotation degeneracy of the diagonal-striped phase. The
+effect appears to be similar to that in the case of anisotropy of the
+nearest-neighbor hopping: the stripes are oriented in the direction of the
+weaker next-nearest-neighbor hopping.",0511557v1
+2005-11-23,Phase separation in the trapped spinor gases with anisotropic spin-spin interaction,"We investigate the effect of the anisotropic spin-spin interaction on the
+ground state density distribution of the one dimensional spin-1 bosonic gases
+within a modified Gross-Pitaevskii theory both in the weakly interaction regime
+and in the Tonks-Girardeau (TG) regime. We find that for ferromagnetic spinor
+gas the phase separation occurs even for weak anisotropy of the spin-spin
+interaction, which becomes more and more obvious and the component of $m_F=0$
+diminishes as the anisotropy increases. However, no phase separation is found
+for anti-ferromagnetic spinor gas in both regimes.",0511581v2
+2005-11-28,Quantum tunneling induced Kondo effect in single molecular magnets,"We consider transport through a single-molecule magnet strongly coupled to
+metallic electrodes. We demonstrate that for half-integer spin of the molecule
+electron- and spin-tunneling \emph{cooperate} to produce both quantum tunneling
+of the magnetic moment and a Kondo effect in the linear conductance. The Kondo
+temperature depends sensitively on the ratio of the transverse and easy-axis
+anisotropies in a non-monotonic way. The magnetic symmetry of the transverse
+anisotropy imposes a selection rule on the total spin for the occurrence of the
+Kondo effect which deviates from the usual even-odd alternation.",0511664v2
+2005-12-07,Finite-size scaling in anisotropic systems,"We present analytical results for the finite-size scaling in d--dimensional
+O(N) systems with strong anisotropy where the critical exponents (e.g. \nu_{||}
+and \nu_{\perp}) depend on the direction. Prominent examples are systems with
+long-range interactions, decaying with the interparticle distance r as
+r^{-d-\sigma} with different exponents \sigma in corresponding spatial
+directions, systems with space-""time""a anisotropy near a quantum critical point
+and systems with Lifshitz points. The anisotropic properties involve also the
+geometry of the systems. We consider systems confined to a d-dimensional layer
+with geometry L^{m}\times\infty^{n}; m+n=d and periodic boundary conditions
+across the finite m dimensions. The arising difficulties are avoided using a
+technics of calculations based on the analytical properties of the generalized
+Mittag-Leffler functions.",0512146v1
+2005-12-07,Effect of spin-orbit interaction on a magnetic impurity in the vicinity of a surface,"We propose a new mechanism for surface-induced magnetic anisotropy to explain
+the thickness-dependence of the Kondo resistivity of thin films of dilute
+magnetic alloys. The surface anisotropy energy, generated by spin-orbit
+coupling on the magnetic impurity itself, is an oscillating function of the
+distance d from the surface and decays as 1/d^2. Numerical estimates based on
+simple models suggest that this mechanism, unlike its alternatives, gives rise
+to an effect of the desired order of magnitude.",0512154v1
+2006-02-15,Effect of step stiffness and diffusion anisotropy on the meandering of a growing vicinal surface,"We study the step meandering instability on a surface characterized by the
+alternation of terraces with different properties, as in the case of Si(001).
+The interplay between diffusion anisotropy and step stiffness induces a finite
+wavelength instability corresponding to a meandering mode. The instability sets
+in beyond a threshold value which depends on the relative magnitudes of the
+destabilizing flux and the stabilizing stiffness difference. The meander
+dynamics is governed by the conserved Kuramoto-Sivashinsky equation, which
+display spatiotemporal coarsening.",0602353v1
+2006-03-07,Reentrant anisotropic phases in a two-dimensional hole system,"Anisotropic charge transport is observed in a two-dimensional (2D) hole
+system in a perpendicular magnetic field at filling factors nu=7/2 and nu=11/2
+for temperatures below 150mK. In stark contrast, the transport at nu=9/2 is
+isotropic for all temperatures. Our results for a two-dimensional hole system
+differ substantially from 2D electron transport where no anisotropy has been
+observed at nu=7/2, the strongest anisotropy occurs at nu=9/2, and reentrant
+behavior is not evident. We attribute this difference to strong spin-orbit
+coupling in the hole system.",0603173v1
+2006-03-20,Triplet superconductivity in a 1D itinerant electron system with transverse spin anisotropy,"In this paper we study the ground state phase diagram of a one-dimensional
+t-J-U model away from half-filling. In the large-bandwidth limit and for
+ferromagnetic exchange with easy-plane anisotropy a phase with gapless charge
+and massive spin excitations, characterized by the coexistence of triplet
+superconducting and spin density wave instabilities is realized in the ground
+state. With increasing ferromagnetic exchange transitions into a ferrometallic
+and then a spin gapped triplet superconducting phase take place.",0603504v1
+2006-05-06,Nutations of spin in the quasi-isotropic superfluid A-like phase of 3He,"The order parameter of the quasi-isotropic superfluid A-like phase of 3He is
+rewritten in a simple form. Effect of anisotropy of magnetic susceptibility of
+this phase on the frequencies of the spatially uniform oscillations of spin and
+the spin part of its order parameter are found. Anisotropy of susceptibility
+has pronounced effect on the low-frequency mode, which is analogous to
+nutations of the asymmetric top. Possibility of observation of the
+nutation-like mode is discussed.",0605126v1
+2006-05-22,Kondo-transport spectroscopy of single molecule magnets,"We demonstrate that in a single molecule magnet (SMM) strongly coupled to
+electrodes the Kondo effect involves all magnetic excitations. This Kondo
+effect is induced by the quantum tunneling of the magnetic moment (QTM).
+Importantly, the Kondo temperature $T_K$ can be much larger than the magnetic
+splittings. We find a strong modulation of the Kondo effect as function of the
+transverse anisotropy parameter or a longitudinal magnetic field. For both
+integer and half-integer spin this can be used for an accurate transport
+spectroscopy of the magnetic states in low magnetic fields on the order of the
+easy-axis anisotropy parameter. We set up a relationship between the Kondo
+effects for successive integer and half-integer spins.",0605514v1
+2006-06-27,Compressed Silica Aerogels for the Study of Superfluid 3He,"We have performed Small Angle X-ray Scattering (SAXS) on uniaxially strained
+aerogels and measured the strain-induced structural anisotropy. We use a model
+to connect our SAXS results to anisotropy of the 3He quasiparticle mean free
+path in aerogel.",0606702v1
+2006-08-19,Spin dynamics in molecular ring nanomagnets: Significant effect of acoustic phonons and magnetic anisotropies,"The nuclear spin-lattice relaxation rate 1/T_1_ is calculated for magnetic
+ring clusters by fully diagonalizing their microscopic spin Hamiltonians.
+Whether the nearest-neighbor exchange interaction J is ferromagnetic or
+antiferromagnetic, 1/T_1_ versus temperature T in ring nanomagnets may be
+peaked at around k_B_T=|J| provided the lifetime broadening of discrete energy
+levels is in proportion to T^3^. Experimental findings for ferromagnetic and
+antiferromagnetic Cu^II^ rings are reproduced with crucial contributions of
+magnetic anisotropies as well as acoustic phonons.",0608438v1
+2006-08-23,Influence of impurity on isotope coefficient of superconductors,"We study the influence of anisotropy of the impurity potential on isotope
+coefficient of an impure superconductor in Born limit. From the isotope
+coefficient of non-magnetic and magnetic impurities including an angle-resolved
+Fermi surface density of state, anisotropy order parameter and impure
+potential, we make the assumption that the form of them are in the harmonic
+form and are investigated. Our numerical calculation of isotope coefficient can
+fit well with experimental data of high-Tc superconductors.",0608497v1
+2006-09-06,"Magnitude and crystalline anisotropy of hole magnetization in (Ga,Mn)As","Theory of hole magnetization Mc in zinc-blende diluted ferromagnetic
+semiconductors is developed relaxing the spherical approximation of earlier
+approaches. The theory is employed to determine Mc for (Ga,Mn)As over a wide
+range of hole concentrations and a number of crystallographic orientations of
+Mn magnetization. It is found that anisotropy of Mc is practically negligible
+but the obtained magnitude of Mc is significantly greater than that determined
+in the spherical approximation. Its sign and value compares favorably with the
+results of available magnetization measurements and ferromagnetic resonance
+studies.",0609128v1
+2006-09-25,"Light-Induced Magnetic Precession in (Ga,Mn)As Slabs: Hybrid Standing-Wave Damon-Eshbach Modes","Coherent oscillations associated with spin precessions were observed in
+ultrafast optical experiments on ferromagnetic (Ga,Mn)As films. Using a
+complete theoretical description of the processes by which light couples to the
+magnetization, values for the exchange and anisotropy constants were obtained
+from the field-dependence of the magnon frequencies and the
+oscillation-amplitude ratios. Results reveal a relatively large negative
+contribution to the energy due to surface anisotropy leading to excitations
+that are a mixture of bulk waves and surface modes.",0609646v1
+2006-10-23,Mechanism of temperature dependence of the magnetic anisotropy energy in ultrathin Cobalt and Nickel films,"Temperature dependent FMR-measurements of Ni and Co films are analysed using
+a microscopic theory for ultrathin metallic systems. The mechanism governing
+the temperature dependence of the magnetic anisotropy energy is identified and
+discussed. It is reduced with increasing temperature. This behavior is found to
+be solely caused by magnon excitations.",0610649v1
+2006-10-27,Charge and spin transport in spin valves with anisotropic spin relaxation,"We investigate effects of spin-orbit splitting on electronic transport in a
+spin valve consisting of a large quantum dot defined on a two-dimensional
+electron gas with two ferromagnetic contacts. In the presence of both structure
+inversion asymmetry (SIA) and bulk inversion asymmetry (BIA) a giant anisotropy
+in the spin-relaxation times has been predicted. We show how such an anisotropy
+affects the electronic transport properties such as the angular
+magnetoresistance and the spin-transfer torque. Counterintuitively, anisotropic
+spin-relaxation processes sometimes enhance the spin accumulation.",0610770v1
+2006-11-30,NMR of superfluid 3He in anisotropic aerogel,"We report on orientation of the order parameter in the 3He-A and 3He-B phases
+caused by aerogel anisotropy. In 3He-A we have observed relatively homogeneous
+NMR line with an anomalously large negative frequency shift. We can attribute
+this effect to an orientation of orbital momentum along the axis of density
+anisotropy. The similar orientation effect we have seen in 3He-B. We can
+measure the A-phase Leggett frequency, which shows the same energy gap
+suppression as in the B-phase. We observe a correlation of A - B transition
+temperature and NMR frequency shift.",0612007v1
+2006-12-22,Magnon Dispersion and Anisotropies in SrCu$_2$(BO$_3$)$_2$,"We study the dispersion of the magnons (triplet states) in
+SrCu$_2$(BO$_3$)$_2$ including all symmetry-allowed Dzyaloshinskii-Moriya
+interactions. We can reduce the complexity of the general Hamiltonian to a new
+simpler form by appropriate rotations of the spin operators. The resulting
+Hamiltonian is studied by both perturbation theory and exact numerical
+diagonalization on a 32-site cluster. We argue that the dispersion is dominated
+by Dzyaloshinskii-Moriya interactions. We point out which combinations of these
+anisotropies affect the dispersion to linear-order, and extract their
+magnitudes.",0612598v2
+2007-01-19,"Exploiting Locally Imposed Anisotropies in (Ga,Mn)As: a Non-volatile Memory Device","Progress in (Ga,Mn)As lithography has recently allowed us to realize
+structures where unique magnetic anisotropy properties can be imposed locally
+in various regions of a given device. We make use of this technology to
+fabricate a device in which we study transport through a constriction
+separating two regions whose magnetization direction differs by 90 degrees. We
+find that the resistance of the constriction depends on the flow of the
+magnetic field lines in the constriction region and demonstrate that such a
+structure constitutes a non-volatile memory device.",0701478v1
+2007-02-12,Multicritical behavior of two-dimensional anisotropic antiferromagnets in a magnetic field,"We study the phase diagram and multicritical behavior of anisotropic
+Heisenberg antiferromagnets on a square lattice in the presence of a magnetic
+field along the easy axis. We argue that, beside the Ising and XY critical
+lines, the phase diagram presents a first-order spin-flop line starting from
+T=0, as in the three-dimensional case. By using field theory we show that the
+multicritical point where these transition lines meet cannot be O(3) symmetric
+and occurs at finite temperature. We also predict how the critical temperature
+of the transition lines varies with the magnetic field and the uniaxial
+anisotropy in the limit of weak anisotropy.",0702273v1
+2007-02-17,Magnetic Anisotropy of Co2+ as Signature of Intrinsic Ferromagnetism in ZnO:Co,"We report on the magnetic properties of thoroughly characterized Zn1-xCoxO
+epitaxial thin films, with low Co concentration, x=0.003-0.005. Magnetic and
+EPR measurements, combined with crystal field theory, reveal that isolated Co2+
+ions in ZnO possess a strong single ion anisotropy which leads to an ""easy
+plane"" ferromagnetic state when the ferromagnetic Co-Co interaction is
+considered. We suggest that the peculiarities of the magnetization process of
+this state can be viewed as a signature of intrinsic ferromagnetism in ZnO:Co
+materials.",0702410v1
+2007-02-21,Magnetic Anisotropy of Deposited Transition Metal Clusters,"We present results of magnetic torque calculations using the fully
+relativistic spin-polarized Korringa-Kohn-Rostoker approach applied to small Co
+and Fe clusters deposited on the Pt(111) surface. From the magnetic torque one
+can derive among others the magnetic anisotropy energy (MAE). It was found that
+this approach is numerically much more stable and also computationally less
+demanding than using the magnetic force theorem that allows to calculate the
+MAE directly. Although structural relaxation effects were not included our
+results correspond reasonably well to recent experimental data.",0702483v1
+1993-10-06,Cosmological Rotation of Quantum-Mechanical Origin and Anisotropy of the Microwave Background,"It is shown that rotational cosmological perturbations can be generated in
+the early Universe, similarly to gravitational waves. The generating mechanism
+is quantum-mechanical in its nature, and the created perturbations should now
+be placed in squeezed vacuum quantum states. The physical conditions under
+which the phenomenon can occur are formulated. The generated perturbations can
+contribute to the large-angular-scale anisotropy of the cosmic microwave
+background radiation. An exact formula is derived for the angular correlation
+function of the temperature variations caused by the quantum-mechanically
+generated rotational perturbations. The multipole expansion begins from the
+dipole component. The comparison with the case of gravitational waves is made.",9310011v1
+1994-10-18,Cosmological Perturbations of Quantum Mechanical Origin and Anisotropy of the Microwave Background Radiation,"A theory of quantum-mechanical generation of cosmological perturbations is
+considered. The conclusion of this study is that if the large-angular-scale
+anisotropy in the cosmic microwave background radiation is caused by the
+long-wavelength cosmological perturbations of quantum mechanical origin, they
+are, most likely, gravitational waves, rather than density perturbations or
+rotational perturbations. Some disagreements with previous publications are
+clarified. This contribution to the Proceedings is based on Reference~[34].",9410025v1
+1996-04-05,Stochastic Processes and Diffusion on Spaces with Local Anisotropy,"The purpose of this work is to extend the formalism of stochastic calculus to
+the case of spaces with local anisotropy (modeled as vector bundles with
+compatible nonlinear and distinguished connections and metric structures and
+containing as particular cases different variants of Kaluza--Klein and
+generalized Lagrange and Finsler spaces). We shall examine nondegenerate
+diffusions on the mentioned spaces and theirs horizontal lifts.",9604014v1
+1996-09-27,The Implications of the Microwave Background Anisotropies for Laser-Interferometer-Tested Gravitational Waves,"The observed microwave background anisotropies in combination with the theory
+of quantum mechanically generated cosmological perturbations predict a well
+measurable amount of relic gravitational waves in the frequency intervals
+tested by LISA and ground-based laser interferometers.",9609062v2
+1996-11-29,Inflation for Bianchi IX model,"The influence of Inflation on initial (i.e. at Planck's epoch) large
+anisotropy of the Universe is studied, considering a more general metric than
+the isotropic one: the locally rotationally symmetric (L.R.S.) Bianchi IX
+metric. We find, then, a large set of initial conditions of intrinsic curvature
+and shear allowing an inflationary epoch that make the anisotropy negligible.
+These are not trivial because of the non-linearity of the Einstein's equations.",9612001v1
+1997-11-03,On the role of density inhomogeneity and local anisotropy in the fate of spherical collapse,"We obtain an expression for the active gravitational mass of a collapsing
+fluid distribution, which brings out the role of density inhomogeneity and
+local anisotropy in the fate of spherical collapse.",9711002v1
+1998-06-25,Local anisotropy of space in a frame of reference co-moving with the Earth,"We consider, in the framework of General Relativity, the linear approximation
+of the gravitational field of the Earth taking into account its mass, its
+quadrupole moment, its shape and its diurnal rotation.
+  We conclude that in the frame of reference co-moving with the Earth the local
+anisotropy of the space is of the order of $10^{-12}-10^{-13}$ and could be
+observed.",9806099v1
+2000-01-21,Quantum Evolution of the Bianchi Type I Model,"The behaviour of the flat anisotropic model of the Universe with a scalar
+field is explored within the framework of quantum cosmology. The principal
+moment of the account of an anisotropy is the presence either negative
+potential barrier or positive repelling wall. In the first case occur the above
+barrier reflection of the wave function of the Universe, in the second one
+there is bounce off a potential wall. The further evolution of the Universe
+represents an exponential inflating with fast losses of an anisotropy and
+approach to the standard cosmological scenario.",0001065v2
+2000-10-06,General Relativistic Contribution to Polarization of the Cosmic Microwave Background Anisotropy,"We solve the wave equation for the electromagnetic field tensors associated
+with the CMBR photons in a universe with scalar metric perturbations. We show
+that the coupling of the electromagnetic fields with the curvature associated
+with the scalar perturbations gives rise to an optical rotation of the
+microwave background photons. The magnitude of the gravitationally generated
+V-Stokes parameter anisotropy $\Delta_V$, is however very small compared to the
+linear polarisation caused by Thomson scattering.",0010022v1
+2002-10-22,Bianchi type I universes with dilaton and magnetic fields,"We consider the dynamics of a Bianchi type I spacetime in the presence of
+dilaton and magnetic fields. The general solution of the Einstein-Maxwell
+dilaton field equations can be obtained in an exact parametric form. Depending
+on the numerical values of the parameters of the model there are three distinct
+classes of solutions. The time evolution of the mean anisotropy, shear and
+deceleration parameter is considered in detail and it is shown that a
+magnetic-dilaton anisotropic Bianchi type I geometry does not isotropize, the
+initial anisotropy being present in the universe for all times.",0210073v1
+2004-03-02,Annual modulation of the Galactic binary confusion noise bakground and LISA data analysis,"We study the anisotropies of the Galactic confusion noise background and its
+effects on LISA data analysis. LISA has two data streams of the gravitational
+waves signals relevant for low frequency regime. Due to the anisotropies of the
+background, the matrix for their confusion noises has off-diagonal components
+and depends strongly on the orientation of the detector plane. We find that the
+sky-averaged confusion noise level $\sqrt {S(f)}$ could change by a factor of 2
+in three months, and would be minimum when the orbital position of LISA is
+either around the spring or autumn equinox.",0403014v1
+2005-09-07,A locally anisotropic geometrical model of space-time based on CMBR,"We study a locally anisotropic model of General Relativity in the framework
+of a more general geometrical structure than the Riemannian one. In this model
+the observable anisotropy of the CMBR (WMAP) is represented by a tensor of
+anisotropy and it is included in the metric structure of space-time. As well,
+some interesting special cases of spaces are considered.",0509020v3
+2005-11-30,Indications for a preferred reference frame from an ether-drift experiment,"We present a fully model-independent analysis of the extensive observations
+reported by a recent ether-drift experiment in Berlin. No a priori assumption
+is made on the nature of a hypothetical preferred frame. We find a remarkable
+consistency with an Earth's cosmic motion exhibiting an average declination
+angle |\gamma|\sim 43^o and with values of the RMS anisotropy parameter
+(1/2-\beta+\delta) that are one order of magnitude larger than the presently
+quoted ones. This might represent the first modern indication for a preferred
+frame and for a non-zero anisotropy of the speed of light.",0511160v1
+2002-05-22,Azimuthal anisotropy of K0s and Lambda prduction at mid-rapidity from Au+Au collisions at root s = 130 GeV,"We report STAR results on the azimuthal anisotropy parameter v2 for strange
+particles K0S, L and Lbar at midrapidity in Au+Au collisions at sNN = 130 GeV
+at RHIC. The value of v2 as a function of transverse momentum of the produced
+particles pt and collision centrality is presented for both particles up to pt
+3.0 GeV/c. A strong pt dependence in v2 is observed up to 2.0 GeV/c. The v2
+measurement is compared with hydrodynamic model calculations. The physics
+implications of the pt integrated v2 magnitude as a function of particle mass
+are also discussed.",0205072v1
+1996-10-28,One-loop anisotropy for improved actions,"We determine the one-loop correction to the anisotropy factor for the square
+Symanzik improved lattice action, extracted fromthe finite volume effective
+action for SU(N) gauge theories in the background of a zero-momentum gauge
+field. The result is smaller by approximately a factor 3 than the one-loop
+correction for the anisotropic Wilson action. We also comment on the
+Hamiltonian limit.",9610036v1
+1999-08-30,Some effects of the anisotropy in a simple lattice gauge model at finite temperature,"Monte Carlo simulations are carried out on the (3+1)-dimensional Z(2)
+anisotropic lattice model, and a new method to simulate extremely anisotropic
+lattice systems with discrete symmetries is proposed. Dependence of the
+temporal and spatial average plaquette, Wilson loops on the anisotropy
+parameter is presented.",9908053v1
+2000-06-22,Casimir scaling of SU(3) static potentials,"Potentials between static colour sources in eight different representations
+are computed in four dimensional SU(3) gauge theory. The simulations have been
+performed with the Wilson action on anisotropic lattices where the renormalised
+anisotropies have been determined non-perturbatively. After an extrapolation to
+the continuum limit we are able to exclude any violations of the Casimir
+scaling hypothesis that exceed 5% for source separations of up to 1 fm.",0006022v2
+2001-03-29,Non-perturbative computation of the bubble nucleation rate in the cubic anisotropy model,"At first order phase transitions the transition proceeds through droplet
+nucleation and growth. We discuss a lattice method for calculating the droplet
+nucleation rate, including the complete dynamical factors. The method is
+especially suitable for very strongly suppressed droplet nucleation, which is
+often the case in physically interesting transitions. We apply the method to
+the 3-dimensional cubic anisotropy model in a parameter range where the model
+has a radiatively induced strong first order phase transition, and compare the
+results with analytical approaches.",0103036v1
+2002-09-03,Dynamical fermions on anisotropic lattices,"We report on our study of two-flavor full QCD on anisotropic lattices using
+$O(a)$-improved Wilson quarks coupled with an RG-improved glue. The bare gauge
+and quark anisotropies corresponding to the renormalized anisotropy
+$\xi=a_s/a_t = 2$ are determined as functions of $\beta$ and $\kappa$, using
+the Wilson loop and the meson dispersion relation at several lattice cutoffs
+and quark masses.",0209026v2
+2003-12-06,Numerical study of staggered fermion on anisotropic lattices,"We study calibration procedures of the staggered quarks on anisotropic
+lattices in the quenched approximation and in $N_f = 2$ dynamical simulations.
+For the calibration conditions we adopt the hadronic radii $r_0$ and the meson
+masses in the temporal and spatial directions. On the quenched lattice, we
+calibrate the quark field and compare the result with the result determined
+using the meson dispersion relation. In dynamical simulations, we determine the
+anisotropy parameters $\gamma_G$ and $\gamma_F$ simultaneously within 1%
+accuracy at renormalized anisotropy $\xi = a_s/a_t = 4$.",0312010v1
+2006-03-15,Static Quark Potential and the Renormalized Anisotropy on Tadpole Improved Anisotropic Lattices,"Static quark potential is studied using a tadpole improved gauge lattice
+action. The scale is set using the potential for a wide range of bare
+parameters.
+  The renormalized anisotropy of the lattice is also measured.",0603015v1
+1992-07-16,"COBE, Inflation, and Light Scalars","Comparison of theobservedanisotropy with that predicted iadiabaticDM models
+suggest that much of thserved signal may be due to long wavelenh gravitational
+waves. In inflationary models this requires the generation of tensor
+fluctuations to be at least comparable to scalar density fltuations. This i is
+feasible, but depends sensitively on the inflaton potential. Alternatively,
+isocurvature quantum fluctuations in an axion-like field could produce a
+quadrupole anisotropy proportional to the gravitational wave anisotropy,k
+independent of the inflaton potential. These could also produce large scale
+structure with more power on larger scales than their adiabatic counterparts.",9207243v1
+1992-10-24,Topological Defect Models of Structure Formation After the COBE Discovery of CMB Anisotropies,"The COBE satellite has discovered anisotropies in the cosmic microwave
+background (CMB) consistent with a scale invariant spectrum of density
+perturbations. As reviewed in this lecture, topological defect models of
+structure formation generically produce such a spectrum. We give a summary of
+the cosmic string and global texture models, focusing on distinct observational
+signatures in large-scale structure surveys and in the microwave background. It
+is shown that the amplitude of the CMB quadrupole detected by COBE is in good
+agreement with the predictions of the cosmic string model.",9210261v1
+1996-10-22,"$ε$ expansion analysis of very weak first-order transitions in the cubic anisotropy model, Part II","A companion article analyzed very weakly first-order phase transitions in the
+cubic anisotropy model using $\eps$ expansion techniques. We extend that
+analysis to a calculation of the relative discontinuity of specific heat across
+the transition.",9610448v2
+2001-12-13,Azimuthal anisotropy of jet quenching at LHC,"We analyze the azimuthal anisotropy of jet spectra due to energy loss of hard
+partons in quark-gluon plasma, created initially in nuclear overlap zone in
+collisions with non-zero impact parameter. The calculations are performed for
+semi-central Pb-Pb collisions at LHC energy.",0112180v1
+2003-04-01,Extracting the jet azimuthal anisotropy from higher order cumulants,"We analyze the method for calculation of a coefficient of jet azimuthal
+anisotropy without reconstruction of the nuclear reaction plane considering the
+higher order correlators between the azimuthal position of jet axis and the
+angles of particles not incorporated in the jet. The reliability of this
+technique in the real physical situation under LHC conditions is illustrated.",0304009v1
+2003-10-31,"Detectability of the Sgr Dwarf Leading Tidal Stream with Auger, EUSO or OWL","We point out that if heavy metastable particles composing the dark matter of
+our galaxy are responsible for the ultra-high energy cosmic rays (UHECR) then
+the leading tidal stream of the Sagittarius dwarf galaxy could be detected
+through UHECR. The signal would be an anisotropy in the UHECR flux smaller than
+the telltale anisotropy towards the galactic center that would first establish
+unstable dark matter as the origin of the UHECR.",0311001v2
+1992-03-12,New Integrable Deformations of Higher Spin Heisenberg-Ising Chains,"We show that the anisotropic Heisenberg-Ising chains with higher spin allow,
+for special values of the anisotropy, integrable deformations intimately
+related to the theory of quantum groups at roots of unity. For the spin one
+case we construct and study the symmetries of the hamiltonian which depends on
+a spectral variable belonging to an elliptic curve. One of the points of this
+curve yields the Fateev-Zamolodchikov hamiltonian of spin one and anisotropy
+$\Delta = \frac{ q^2 + q^{-2}}{2} $ with $q$ a cubic root of unity. In some
+other special points the spin degrees of freedom as well as the hamiltonian
+splits into pieces governed by a larger symmetry.",9203035v1
+1999-12-27,Ground State of the Quantum Symmetric Finite Size XXZ Spin Chain with Anisotropy Parameter $Δ= {1/2}$,"We find an analytic solution of the Bethe Ansatz equations (BAE) for the
+special case of a finite XXZ spin chain with free boundary conditions and with
+a complex surface field which provides for $U_q(sl(2))$ symmetry of the
+Hamiltonian. More precisely, we find one nontrivial solution, corresponding to
+the ground state of the system with anisotropy parameter $\Delta = {1/2}$
+corresponding to $q^3 = -1$.",9912252v1
+2001-05-10,Chiral stabilization of the renormalization group for flavor and color anisotropic current interactions,"We propose an all-orders beta function for current-current interactions in 2d
+with flavor anisotropy. When the number of left-moving and right-moving flavors
+are unequal, the beta function has a non-trivial fixed point at finite values
+of the couplings. We also extend the computation to simple cases with both
+flavor and color anisotropy.",0105092v2
+1996-07-11,Anisotropy of Growth of the Close-Packed Surfaces of Silver,"The growth morphology of clean silver exhibits a profound anisotropy: The
+growing surface of Ag(111) is typically very rough while that of Ag(100) is
+smooth and flat. This serious and important difference is unexpected, not
+understood, and hitherto not observed for any other metal. Using density
+functional theory calculations of self-diffusion on flat and stepped Ag(100) we
+find, for example, that at flat regions a hopping mechanism is favored, while
+across step edges diffusion proceeds by an exchange process. The calculated
+microscopic parameters explain the experimentally reported growth properties.",9607007v1
+2000-04-09,A twist localizes three-dimensional patterns,"A mechanism for the localization of spatially periodic, self-organized
+patterns in anisotropic media which requires systems extended in all three
+spatial dimensions is presented: When the anisotropy axis is twisted the
+pattern becomes localized in planes parallel to the anisotropy axis. An
+analytic description of the effect is developed and used to interpret recent
+experiments in the high-frequency regime of electroconvection by Bohatsch and
+Stannarius [Phys. Rev. E {\bf 60}, 5591 (1999)]. The localization width is
+found to be of the order of magnitude of the geometrical average of pattern
+wavelength and the inverse twist.",0004014v2
+2000-05-09,Manifestation of anisotropy persistence in the hierarchies of MHD scaling exponents,"The first example of a turbulent system where the failure of the hypothesis
+of small-scale isotropy restoration is detectable both in the `flattening' of
+the inertial-range scaling exponent hierarchy, and in the behavior of odd-order
+dimensionless ratios, e.g., skewness and hyperskewness, is presented.
+Specifically, within the kinematic approximation in magnetohydrodynamical
+turbulence, we show that for compressible flows, the isotropic contribution to
+the scaling of magnetic correlation functions and the first anisotropic ones
+may become practically indistinguishable. Moreover, skewness factor now
+diverges as the P\'eclet number goes to infinity, a further indication of
+small-scale anisotropy.",0005019v1
+1997-11-07,Reconstructing azimuthal distributions in nucleus-nucleus collisions,"Azimuthal distributions of particles produced in nucleus-nucleus collisions
+are measured with respect to an estimated reaction plane which, because of
+finite multiplicity fluctuations, differs in general from the true reaction
+plane. It follows that the measured distributions do not coincide with the true
+ones. I propose a general method of reconstructing the Fourier coefficients of
+the true azimuthal distributions from the measured ones. This analysis suggests
+that the Fourier coefficients are the best observables to characterize
+azimuthal anisotropies because, unlike other observables such as the in-plane
+anisotropy ratio or the squeeze-out ratio, they can be reconstructed
+accurately.",9711003v2
+2002-06-10,Azimuthal anisotropy and correlations in the hard scattering regime at RHIC,"Azimuthal anisotropy ($v_2$) and two-particle angular correlations of high
+$p_T$ charged hadrons have been measured in Au+Au collisions at
+$\sqrt{s_{NN}}$=130 GeV for transverse momenta up to 6 GeV/c, where hard
+processes are expected to contribute significantly. The two-particle angular
+correlations exhibit elliptic flow and a structure suggestive of fragmentation
+of high $p_T$ partons. The monotonic rise of $v_2(p_T)$ for $p_T<2$ GeV/c is
+consistent with collective hydrodynamical flow calculations. At $\pT>3$ GeV/c a
+saturation of $v_2$ is observed which persists up to $p_T=6$ GeV/c.",0206006v2
+2002-08-22,Azimuthal anisotropy of K^0_S and Lambda production at mid-rapidity from Au+Au collisions at root s_NN = 130 GeV,"We report STAR results on the azimuthal anisotropy parameter v2 for strange
+particles K0S and Lambda at midrapidity in Au+Au collisions at /s_NN = 130 GeV
+at RHIC. The value of v2 as a function of transverse momentum pt and collision
+centrality is presented for both particles and compared to model calculations.
+A strong pt dependence in v2 is observed up to pt ~2.0 GeV/c where v2 begins to
+saturate.",0208013v1
+2002-10-02,Two Particle Azimuthal Correlation Measurements in PHENIX,"Two particle azimuthal correlation functions are presented for charged
+hadrons produced in Au-Au collisions at RHIC sqrt(s_NN)=200 GeV.The correlation
+functions indicate sizeable asymmetries and anisotropies. The trend of the
+asymmetries is compatible with the presence of emission patterns associated
+with mini-jets. The magnitude and the trend of the differential anisotropies
+v_2(p_T) and v_2(N_Part), provide important model constraints.",0210007v2
+2002-10-18,Azimuthal Anisotropy of Charged and Identified High $p_T$ Hadrons in Au+Au Collisions at RHIC,"We report new results on $v_2(p_T)$ for Au+Au collisions at
+$\sqrt{s_{NN}}$=200 GeV for charged hadrons, pions, kaons, (anti)protons,
+$K^0_s$, and $\Lambda$. The analysis is extended to $p_T=12$ GeV/c for charged
+hadrons and $p_T=4$ GeV/c for identified particles. A comparison of the
+azimuthal anisotropy of charged hadrons measured at \sqrtsNN=130 and 200 GeV is
+presented. The $p_T$-dependence of baryon versus meson elliptic flow is
+discussed.",0210027v2
+2002-11-13,Transverse Dynamics at RHIC,"Studies of <p_{T}>, transverse momentum spectra and anisotropy flow from
+nuclear collisions at RHIC indicate early thermalization and strong collective
+expansion. We propose a systematic study of the anisotropy parameter $v_2$ and
+the transverse momentum distributions of $\phi, \Omega, D^0, \Lambda_C$ and $J
+/ \psi$ in order to extract information on partonic collective flow.",0211012v1
+2002-12-12,Flow and non-flow event anisotropies at the SPS,"A study of differential elliptic event anisotropies (v_2) of charged
+particles and high-pt pions in 158 AGeV/c Pb+Au collisions is presented.
+Results from correlations with respect to the event plane and from two-particle
+azimuthal correlations are compared. The latter give systematically higher v_2
+values at pt>1.2GeV/c providing possibly an evidence of a non-flow semihard
+component.",0212013v2
+2005-02-26,Effect of Finite Granularity of Detectors on Anisotropy Coefficients,"The coefficients that describe the anisotropy in the azimuthal distribution
+of particles are lower when the particles are recorded in a detector with
+finite granularity and measures only hits. This arises due to loss of
+information because of multiple hits in any channel. The magnitude of this loss
+of signal depends both on the occupancy and on the value of the coefficient.
+These correction factors are obtained for analysis methods differing in detail,
+and are found to be different.",0502023v2
+2005-11-21,PHENIX Measurement of Particle Yields at High pT with Respect toReaction Plane in Au+Au Collisions at sqrt(s) = 200 GeV,"The PHENIX Run 4 Au+Au dataset provides a powerful opportunity for exploring
+the angular anisotropy of identified particle yields at high pT. Complementing
+traditional v2 measurements, we present pi0 yields as a function of angle with
+reaction plane, up to pT 10 GeV/c. The centrality dependence of the angular
+anisotropy allows us to probe the density and path-length dependence of the
+energy loss of hard-scattered partons. We will discuss various mechanisms for
+particle production in this high pT region.",0511039v1
+2006-07-10,High-pT Particle Production with Respect to the Reaction Plane,"The PHENIX Run4 data-set provides a powerful opportunity for exploring the
+angular anisotropy of identified particle yields at high pT. Complementing
+traditional v2 measurements, we present pi0 yields as a function of emission
+angle with respect to the reaction plane in Au+Au collisions at sqrt(s) = 200
+GeV/c. The centrality dependence of the angular anisotropy allows us to probe
+the density and path-length dependence of the energy loss of hard-scattered
+partons.",0607009v1
+1994-12-14,Fragment Flow and the Nuclear Equation of State,"We use the Boltzmann-Uehling-Uhlenbeck model with a momentum-dependent
+nuclear mean field to simulate the dynamical evolution of heavy ion collisions.
+We re-examine the azimuthal anisotropy observable, proposed as sensitive to the
+equation of state of nuclear matter. We obtain that this sensitivity is maximal
+when the azimuthal anisotropy is calculated for nuclear composite fragments, in
+agreement with some previous calculations. As a test case we concentrate on
+semi-central $^{197}{\rm Au}\ +\ ^{197}{\rm Au}$ collisions at 400 $A$ MeV.",9412020v1
+2001-08-14,Hydrodynamical analysis of flow at RHIC,"We use a hydrodynamical model to describe the evolution of the collision
+system at collision energies sqrt{s}=130 and 200 GeV. At lower sqrt{s}=130 GeV
+energy we compare the results obtained assuming fast or slow thermalization
+(thermalization times tau_0=0.6 and 4.1 fm/c, respectively) and show that slow
+thermalization fails to reproduce the observed anisotropy of particle
+distribution. At sqrt{s}=200 GeV collision energy our results show anisotropies
+similar to those observed at sqrt{s}=130 GeV.",0108033v1
+2004-02-13,Momentum anisotropies in the quark coalescence model,"Based on the quark coalescence model, we derive relations among the momentum
+anisotropies of mesons and baryons in relativistic heavy ion collisions from a
+given, but arbitrary azimuthal distribution for the partons. Besides the
+familiar even Fourier coefficients such as the elliptic flow, we also pay
+attention to odd Fourier coefficients such as the directed flow, which has been
+observed at finite rapidity even at RHIC energies.",0402049v1
+2004-09-30,Disentangling spatial and flow anisotropy,"Two generalisations of the blast-wave model to non-central nuclear collisions
+are constructed, and elliptic flow as well as azimuthal dependence of
+correlation radii are calculated. Particular attention is paid to how different
+azimuthal dependences of transverse flow direction can cause qualitatively
+different anisotropic fireballs to give same v_2 as a function of the
+transverse momentum. The simultaneous dependence of v_2 and the oscillation of
+correlation radii on both spatial and flow anisotropy is studied in great
+detail.",0409074v2
+2003-06-05,Statistical anisotropy of magnetohydrodynamic turbulence,"Direct numerical simulations of decaying and forced magnetohydrodynamic (MHD)
+turbulence without and with mean magnetic field are analyzed by higher-order
+two-point statistics. The turbulence exhibits statistical anisotropy with
+respect to the direction of the local magnetic field even in the case of global
+isotropy. A mean magnetic field reduces the parallel-field dynamics while in
+the perpendicular direction a gradual transition towards two-dimensional MHD
+turbulence is observed with $k^{-3/2}$ inertial-range scaling of the
+perpendicular energy spectrum. An intermittency model based on the Log-Poisson
+approach, $\zeta_p=p/g^2 +1 -(1/g)^{p/g}$, is able to describe the observed
+structure function scalings.",0306045v1
+2003-09-15,Local phase structure of wave dislocation lines: twist and twirl,"Generic wave dislocations (phase singularities, optical vortices) in three
+dimensions have anisotropic local structure, which is analysed, with emphasis
+on the twist of surfaces of equal phase along the singular line, and the
+rotation of the local anisotropy ellipse (twirl). Various measures of twist and
+twirl are compared in specific examples, and a theorem is found relating the
+(quantised) topological twist and twirl for a closed dislocation loop with the
+anisotropy C line index threading the loop.",0309069v2
+2004-11-21,Plateau Instability of Liquid Crystalline Cylinder in Magnetic Field,"The capillary instability of a LC cylinder in magnetic field is considered
+using an energy approach. The boundary problem is solved in the linear
+approximation of the anisotropy $\chi_a$ of the magnetic susceptibility $\chi$.
+The effect of anisotropy, in the region $1\gg|\chi|>|\chi_a|\gg \chi^2$, can be
+strong enough to counteract and even reverse the tendency of the field to
+enhance stabilization by enlarging the cut--off wave number $k_s$ beyond the
+conventional one set by Rayleigh.",0411200v1
+2004-07-17,Quantum teleportation via two qubit Heisenberg XY chain - Effects of anisotropy and magnetic field,"In this paper, we study the influence of anisotropy on the usefulness, of the
+entanglement in a two-qubit Heisenberg XY chain at thermal equilibrium in the
+presence of an external magnetic field, as resource for quantum teleportation
+via the standard teleportation protocol. We show that the nonzero thermal
+entanglement produced by adjusting the external magnetic field strength beyond
+some critical strength is a useful resource. We also considered entanglement
+teleportation via two two-qubit Heisenberg XY chains.",0407137v1
+2007-04-22,Sm2Al: Another ferromagnet with spin-orbital compensation?,"We report the observation of a compensation point in the temperature
+dependence of magnetization data of polycrystalline Sm2Al. Magnetization
+measurements show that this compound magnetically orders at about 150 K. Below
+this temperature, the magnetization data shows a compensation point, which
+shifts with field. Hysteresis loops obtained below the compensation temperature
+show that the compound possesses exchange anisotropy. Both the exchange
+anisotropy field and the coercive field are found to be quite large and
+comparable to those of the classical spin-orbit compensated ferromagnet
+(Sm,Gd)Al2. The heat capacity data also suggest that there are similarities
+between (Sm,Gd)Al2 and Sm2Al.",0704.2864v1
+2007-04-23,Dynamical stability for finite quantum spin chains against a time-periodic inhomogeneous perturbation,"We investigate dynamical stability of the ground state against a
+time-periodic and spatially-inhomogeneous magnetic field for finite quantum XXZ
+spin chains. We use the survival probability as a measure of stability and
+demonstrate that it decays as $P(t) \propto t^{-1/2}$ under a certain
+condition. The dynamical properties should also be related to the level
+statistics of the XXZ spin chains with a constant spatially-inhomogeneous
+magnetic field. The level statistics depends on the anisotropy parameter and
+the field strength. We show how the survival probability depends on the
+anisotropy parameter, the strength and frequency of the field.",0704.2922v1
+2007-05-08,Anisotropic probabilistic cellular automaton for a predator-prey system,"We consider a probabilistic cellular automaton to analyze the stochastic
+dynamics of a predator-prey system. The local rules are Markovian and are based
+in the Lotka-Volterra model. The individuals of each species reside on the
+sites of a lattice and interact with an unsymmetrical neighborhood. We look for
+the effect of the space anisotropy in the characterization of the oscillations
+of the species population densities. Our study of the probabilistic cellular
+automaton is based on simple and pair mean-field approximations and explicitly
+takes into account spatial anisotropy.",0705.1053v1
+2007-05-27,The transition temperature of Ising ferromagnetic thin film with aniaxial anisotropy,"The magnetic properties in the Ising ferromagnetic thin films are studied. By
+transfer matrix method, the transition temperatures are calculated as a
+function of the intra- and interlayer exchange interactions. The transition
+temperatures in the Ising ferromagnetic thin films with uniaxial anisotropy are
+also studied. The results show that the transition temperature changes with the
+film thickness.",0705.3955v3
+2007-06-04,Non-Abelian Plasma Instabilities for Extreme Anisotropy,"Thermalization of quark-gluon plasmas in heavy-ion collisions is a difficult
+theoretical problem. One theoretical goal has been to understand the physics of
+thermalization in the relatively simplifying limit of arbitrarily high energy
+collisions, where the running coupling alpha_s is weak. One of the current
+roadblocks to achieving this goal is lack of knowledge about the behavior of
+plasma instabilities when particle distributions are highly anisotropic. In
+particular, it has not been known how the magnetic fields generated by plasma
+instabilities scale with anisotropy. In this paper, we use numerical
+simulations in a first attempt to determine this scaling.",0706.0490v1
+2007-06-12,Temperature dependence of magnetic anisotropy in bulk and nanoparticles of Pr_0.5Sr_0.5MnO_3,"Nanoparticles (size 20, 40 and 60 nm) of Pr_0.5Sr_0.5MnO_3 are prepared by
+sol-gel technique and their magnetic properties are studied using ferromagnetic
+resonance and magnetization measurements. A comparison with the properties of
+the bulk material shows that the ferromagnetic transition at 265 K remains
+unaffected but the anti-ferromagnetic transition at T_N = 150 K disappears in
+the nanoparticles. Further, the temperature dependence of magnetic anisotropy
+shows a complex behavior, being higher in the nanoparticles at high
+temperatures and lower at lower temperatures in comparison with the bulk.",0706.1662v1
+2007-06-15,Evolution of Anisotropy of Parton System from Relativistic Heavy-Ion Collisions,"Evolution of anisotropy in momentum and coordinate space of the parton system
+produced in relativistic heavy-ion collisions is discussed within the
+free-streaming approximation. The momentum distribution evolves from the
+prolate shape - elongated along the beam - to the oblate one - squeezed along
+the beam. At the same time the eccentricity in the coordinate space, which
+occurs at finite values of impact parameter, decreases. It is argued that the
+parton system reaches local thermodynamic equilibrium before the momentum
+distribution becomes oblate.",0706.2273v3
+2007-06-16,Maxwell Equations with Accounting of Tensor Properties of Time,"The Maxwell equations with accounting for tensors properties of time have
+been considered. The effects that follow from such consideration are described.
+These are the appearance of vacuum polarization, anisotropy of electromagnetic
+wave velocity in vacuum, anisotropy of the vacuum dielectric permittivity,
+rotation of light polarization plane, as well as the existence of longitudinal
+components of electromagnetic wave and the rotational (non-potential) component
+of electric field caused by electric charges.",0706.2414v1
+2007-06-19,A search for possible anisotropies of cosmic rays with 0.1<E<10 EeV in the region of the Galactic Centre,"We present updated results for anisotropy searches in the direction of the
+Galactic Center (GC) at energies in the ranges: 0.1<E<1 EeV and 1<E<10 EeV. We
+use data from the Pierre Auger Observatory up to March, 2007. Present analyzes
+are therefore based on a substantially larger data set than our previous
+published results. A limit on the flux coming from a hypothetical point-like
+neutron source at the GC for 1<E<10 EeV was imposed, and searches for extended
+excesses were also performed.",0706.2669v2
+2007-06-24,Gabay-Toulouse Phase Transition in Heisenberg Spin-Glasses in Three Dimensions,"We examine three-dimensional $\pm J$ Heisenberg models with and without
+random anisotropies in a magnetic field. We calculate both the stiffness
+exponent $\theta_s$ at absolute zero temperature and spin-glass correlation
+lengths for the longitudinal and transverse spin components at finite
+temperatures. We suggest that, contrary to a chirality scenario predicted by
+Kawamura and his co-workers, a Gabay-Toulouse phase transition occurs when the
+anisotropies are absent, although no phase transition occurs when they are
+present.",0706.3493v1
+2007-06-26,Measuring the Expansion of the Universe Through Changes in the CMB Photosphere,"The expansion of the universe may be observed in ``realtime'' by measuring
+changes in the patterns of the anisotropy in the CMB. As the universe ages, the
+surface of decoupling--or the CMB photosphere--moves away from us and samples a
+different gravitational landscape. The response of the CMB to this new
+landscape results in a different pattern than we observe today. The largest
+change occurs at l~900. We show that with an array of detectors that we may
+envision having in a couple of decades, one can in principle measure the change
+in the anisotropy with two high precision measurements separated by a century.",0706.3908v1
+2007-06-27,Correlation in the velocity of a Brownian particle induced by frictional anisotropy and magnetic field,"We study the motion of charged Brownian particles in an external magnetic
+field. It is found that a correlation appears between the components of
+particle velocity in the case of anisotropic friction, approaching
+asymptotically zero in the stationary limit. If magnetic field is smaller
+compared to the critical value, determined by frictional anisotropy, the
+relaxation of the correlation is non-oscillating in time. However, in a larger
+magnetic field this relaxation becomes oscillating. The phenomenon is related
+to the statistical dependence of the components of transformed random force
+caused by the simultaneous influence of magnetic field and anisotropic
+dissipation.",0706.4090v2
+2007-07-11,Orbital-Driven Electronic Structure Changes and the Resulting Optical Anisotropy of the Quasi-Two-Dimensional Spin Gap Compound La4Ru2O10,"We investigated the electronic response of the quasi-two-dimensional spin gap
+compound La4Ru2O10 using optical spectroscopy. We observed drastic changes in
+the optical spectra as the temperature decreased, resulting in anisotropy in
+the electronic structure of the spin-singlet ground state. Using the
+orbital-dependent hopping analysis, we found that orbital ordering plays a
+crucial role in forming the spin gap state in the non-one-dimensional material.",0707.1564v1
+2007-07-27,"Photo-induced precession of magnetization in ferromagnetic (Ga,Mn)As","Precession of magnetization induced by pulsed optical excitation is observed
+in a ferromagnetic semiconductor (Ga,Mn)As by time-resolved magneto-optical
+measurements. It appears as complicated oscillations of polarization plane of
+linearly-polarized probe pulses, but is reproduced by gyromagnetic theory
+incorporating an impulsive change in an effective magnetic field due to changes
+in magnetic anisotropy. It is inferred from the shape of the impulse that the
+changes in anisotropy result from non-equilibrium carrier population: cooling
+of hot photo-carriers and subsequent annihilation of photo-carriers.",0707.4055v2
+2007-08-24,The role of pressure anisotropy on the maximum mass of cold compact stars,"We study the physical features of a class of exact solutions for cold compact
+anisotropic stars. The effect of pressure anisotropy on the maximum mass and
+surface redshift is analysed in the Vaidya-Tikekar model. It is shown that
+maximum compactness, redshift and mass increase in the presence of anisotropic
+pressures; numerical values are generated which are in agreement with
+observation.",0708.3305v1
+2007-08-24,On surface tension for compact stars,"In an earlier treatment it was demonstrated that general relativity gives
+higher values of surface tension in strange stars with quark matter than
+neutron stars.We generate the modified Tolman-Oppenheimer-Volkoff equation to
+incorporate anisotropic matter and use this to show that pressure anisotropy
+provides for a wide range of behaviour in the surface tension than is the case
+with isotropic pressures. In particular it is possible that anisotropy
+drastically decreases the value of the surface tension.",0708.3317v1
+2007-08-27,Anisotropic conductivity of disordered 2DEGs due to spin-orbit interactions,"We show that the conductivity tensor of a disordered two-dimensional electron
+gas becomes anisotropic in the presence of both Rashba and Dresselhaus
+spin-orbit interactions (SOI). This anisotropy is a mesoscopic effect and
+vanishes with vanishing charge dephasing time. Using a diagrammatic approach
+including zero, one, and two-loop diagrams, we show that a consistent
+calculation needs to go beyond a Boltzmann equation approach. In the absence of
+charge dephasing and for zero frequency, a finite anisotropy \sigma_{xy}
+e^2/lhpf arises even for infinitesimal SOI.",0708.3504v2
+2007-09-20,Spin wave resonances in La_{0.7}Sr_{0.3}MnO_{3} films: measurement of spin wave stiffness and anisotropy field,"We studied magnetic field dependent microwave absorption in epitaxial
+La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ films using an X-band Bruker ESR spectrometer. By
+analyzing angular and temperature dependence of the ferromagnetic and spin-wave
+resonances we determine spin-wave stiffness and anisotropy field. The spin-wave
+stiffness as found from the spectrum of the standing spin-wave resonances in
+thin films is in fair agreement with the results of inelastic neutron
+scattering studies on a single crystal of the same composition [Vasiliu-Doloc
+et al., J. Appl. Phys. \textbf{83}, 7343 (1998)].",0709.3204v2
+2007-10-12,Probing Non-Gaussianity In The Cosmic Microwave Background Anisotropies: One Point Distribution Function,"We analyze WMAP 3 year data using the one-point distribution functions to
+probe the non-Gaussianity in the Cosmic Microwave Background (CMB) Anisotropy
+data. Computer simulations are performed to determine the uncertainties of the
+results. We report the non-Gaussianity parameter f_NL is constrained to
+26<f_NL<82 for Q-band, 12<f_NL<67 for V-band, 7<f_NL<64 for W-band and
+23<f_NL<75 for Q+V+W combined data at 95% confidence level (CL).",0710.2371v3
+2007-11-05,Magnetic excitations in vanadium spinels,"We study magnetic excitations in vanadium spinel oxides AV$_2$O$_4$ (A=Zn,
+Mg, Cd) using two models: first one is a superexchange model for vanadium S=1
+spins, second one includes in addition spin-orbit coupling, and crystal
+anisotropy. We show that the experimentally observed magnetic ordering can be
+obtained in both models, however the orbital ordering is different with and
+without spin-orbit coupling and crystal anisotropy. We demonstrate that this
+difference strongly affects the spin-wave excitation spectrum above the
+magnetically ordered state, and argue that the neutron measurement of such
+dispersion is a way to distinguish between the two possible orbital orderings
+in AV$_2$O$_4$.",0711.0732v1
+2007-11-06,Quantum Weibel Instability,"The Weibel instability is analyzed for quantum plasmas described by the
+Wigner-Maxwell model. For a suitable class of electromagnetic potentials, the
+Wigner-Maxwell system is linearized yielding a general dispersion relation for
+transverse electromagnetic waves. For a double Gaussian equilibrium with
+temperature anisotropy, the derived dispersion relation generalizes the
+classical Weibel instability equation. More detailed analytical results are
+obtained for the cases of extreme temperature anisotropy and for a
+three-dimensional water bag distribution. In all cases, quantum effects tends
+to weaken or suppress the instability. Applications are discussed for dense
+astrophysical objects like white dwarfs and neutron stars as well as for
+tunnel-ionized plasmas with controllable perpendicular plasma temperature.",0711.0851v1
+2007-11-19,Azimuthal anisotropy of direct photons,"The electromagnetic bremsstrahlung produced by a quark interacting with
+nucleons or nuclei is azimuthally asymmetric. In the light-cone dipole approach
+this effect is related to the orientation dependent dipole cross section. Such
+a radiation anisotropy is expected to contribute to the azimuthal asymmetry of
+direct photons in pA and AA collisions, as well as in DIS and in the production
+of dileptons.",0711.3010v4
+2007-12-03,In-plane magnetic field phase diagram of superconducting Sr2RuO4,"We develop the Ginzburg - Landau theory of the upper critical field in the
+basal plane of a tetragonal multiband metal in two-component superconducting
+state. It is shown that typical for the two component superconducting state the
+upper critical field basal plane anisotropy and the phase transition splitting
+still exist in a multiband case. However, the value of anisotropy can be
+effectively smaller than in the single band case. The results are discussed in
+the application to the superconducting Sr2RuO4.",0712.0286v3
+2007-12-23,Orthogonalization Properties of Linear Deterministic Polarization Elements,"The conditions under which a linear anisotropic polarization element
+orthogonalizes several polarization states of input totally polarized light
+were studied in the paper. The criterion for orthogonalization was obtained in
+the form of inequality for anisotropy parameters. Orthogonalization properties
+of polarization elements with the most important anisotropy types were
+investigated. The parameters under which orthogonalization occurs, and the
+states that are orthogonalized were found. The loci of these states on the
+Poincare sphere were given for sake of illustration in each case.",0712.3888v1
+2008-01-04,Diagonal charge modulation in the insulating La$_{2-x}$Sr$_x$CuO$_4$,"We show that, due to the Dzyaloshinskii-Moriya and the XY anisotropies, the
+disordered diagonal spin spiral in the insulating La$_{2-x}$Sr$_x$CuO$_4$
+generates a diagonal charge density wave (CDW) with the wave vector twice of
+that of the spin spiral. The amplitude of the CDW depends on values of the
+anisotropies, the doping level, and on the density of states at the chemical
+potential. Based on available experimental data we estimate that for 4% doping
+the amplitude of CDW is about 1/10 of the doping level. We believe that this
+mechanism explains the CDW observed recently in Zn-codoped detwinned
+La$_{2-x}$Sr$_x$CuO$_4$.",0801.0614v1
+2008-01-09,Anisotropy in magnetic and transport properties of Fe1-xCoxSb2,"Anisotropic magnetic and electronic transport measurements were carried out
+on large single crystals of Fe1-xCoxSb2 (0<= x <=1). The semiconducting state
+of FeSb2 evolves into metallic and weakly ferromagnetic by substitution of Fe
+with Co for x<0.5. Further doping induces structural transformation from
+orthorhombic Pnnm structure of FeSb2 to monoclinic P21/c structure of CoSb2
+where semiconducting and diamagnetic ground state is restored again. Large
+magnetoresistance and anisotropy in electronic transport were observed.",0801.1350v2
+2008-01-11,Anisotropy of Electrical Transport and Superconductivity in Metal Chains of Nb2Se3,"In this work we have shown bulk superconductivity and studied the anisotropy
+in both the normal and superconducting states in quasi-1D conductor Nb2Se3.
+Electron - electron Umklapp scattering dominates electronic transport along the
+direction of Nb metal chains as well as perpendicular to it. The
+superconducting state is rather anisotropic with possible multi - band
+features.",0801.1682v1
+2008-01-12,Critical fluctuations and random-anisotropy glass transition in nematic elastomers,"We carry out a detailed deuterium NMR study of local nematic ordering in
+polydomain nematic elastomers. This system has a close analogy to the
+random-anisotropy spin glass. We find that, in spite of the quadrupolar nematic
+symmetry in 3-dimensions requiring a first-order transition, the order
+parameter in the quenched ``nematic glass'' emerges via a continuous phase
+transition. In addition, by a careful analysis of the NMR line shape, we deduce
+that the local director fluctuations grow in a critical manner around the
+transition point. This could be the experimental evidence for the Aizenman-Wehr
+theorem about the quenched impurities changing the order of discontinuous
+transition.",0801.1894v1
+2008-01-20,Strain-induced Fermi contour anisotropy of GaAs 2D holes,"We report measurements of magneto-resistance commensurability peaks, induced
+by a square array of anti-dots, in GaAs (311)A two-dimensional holes as a
+function of applied in-plane strain. The data directly probe the shapes of the
+Fermi contours of the two spin subbands that are split thanks to the spin-orbit
+interaction and strain. The experimental results are in quantitative agreement
+with the predictions of accurate energy band calculations, and reveal that the
+majority spin-subband has a severely distorted Fermi contour whose anisotropy
+can be tuned with strain.",0801.3106v1
+2008-01-29,Interplay among the azimuthally dependent HBT radii and the elliptic flow,"We present a calculation of the elliptic flow and azimuthal dependence of the
+correlation radii in the ellipsoidally symmetric generalization of the
+Buda-Lund model. The elliptic flow is shown to depend only on the flow
+anisotropy while in case of correlation radii both flow and space anisotropy
+play an important role in determining their azimuthal oscillation. We also
+outline a simple procedure for determining the parameters of the model from
+data.",0801.4434v2
+2008-02-08,Theory of reduced singlet pairing without the underlying state of charge stripes in the high-temperature superconductor YBa_2Cu_3O_6.45,"Recently, a strongly enhanced xy anisotropy of magnetic excitations was
+observed in YBa_2Cu_3O_y (YBCO_y) with y=6.45 and Tc=35 K [Science 319, 597
+(2008)]. Unlike the observation in YBCO_6.6 and YBCO_6.85, the anisotropy grows
+to be pronounced at lower temperature and at lower energy, and is not
+suppressed by the onset of superconductivity. We propose that the effect of
+singlet pairing is substantially reduced in YBCO_6.45. This reduction
+concomitantly enhances an order competing with singlet pairing, a strong
+tendency of the so-called d-wave Pomeranchuk instability, leading to the
+magnetic excitations observed experimentally.",0802.1149v2
+2008-02-25,Lecture Notes on CMB Theory: From Nucleosynthesis to Recombination,"These lecture notes comprise an informal but pedagogical introduction to the
+well established physics and phenomenology of the cosmic microwave background
+(CMB) between big bang nucleosynthesis and recombination. The dominant
+properties of the spectrum, temperature anisotropy and polarization anisotropy
+of the CMB all arise from this period. We review the physical processes
+involved and show how they are related to the observed phenomenology.",0802.3688v1
+2008-03-06,Swap Action in a Solid-State Controllable Anisotropic Heisenberg Model,"Correct swap action can be realized via the control of the anisotropic
+Heisenberg interaction in solid-state quantum systems. The conditions of
+performing a swap are derived by the dynamics of arbitrary bipartite pure
+state. It is found that swap errors can be eliminated in the presence of
+symmetric anisotropy. In realistic quantum computers with unavoidable
+fluctuations, the gate fidelity of swap action is estimated. The scheme of
+quantum computation via the anisotropic Heisenberg interaction is implemented
+in a one dimensional quantum dots. The slanting and static magnetic field can
+be used to adjust the anisotropy.",0803.0767v1
+2008-03-07,Strong electron-phonon interaction in multiband superconductors,"We discuss the effects of anisotropy on superconducting critical temperature
+and order parameter in a strongly coupled regime. The multiband representation
+is used as a model for anisotropy. We show that strong coupling effects in
+multiband superconductors lead to pair-breaking due to interband coupling
+because soft phonon modes play the same role as usual impurities. This effect
+makes the order parameters in different bands equal to each other and limits
+the upper bound on critical temperature.",0803.1103v1
+2008-03-08,The Impact of Stochastic Primordial Magnetic Fields on the Scalar Contribution to Cosmic Microwave Background Anisotropies,"We study the impact of a stochastic background of primordial magnetic fields
+on the scalar contribution of CMB anisotropies and on the matter power
+spectrum. We give the correct initial conditions for cosmological perturbations
+and the exact expressions for the energy density and Lorentz force associated
+to the stochastic background of primordial magnetic fields, given a power-law
+for their spectra cut at a damping scale. The dependence of the CMB temperature
+and polarization spectra on the relevant parameters of the primordial magnetic
+fields is illustrated.",0803.1246v1
+2008-04-22,Anisotropic spectra of acoustic type turbulence,"We consider the problem of spectra for acoustic type of turbulence generated
+by shocks being randomly distributed in space. We show that for turbulence with
+a weak anisotropy such spectra have the same dependence in $k$-space as the
+Kadomtsev-Petviashvili (KP) spectrum: $E(k)\sim k^{-2}$. However, the frequency
+spectrum has always the falling $\sim \omega^{-2}$, independently on
+anisotropy. In the strong anisotropic case the energy distribution relative to
+wave vectors takes anisotropic dependence forming in the large $% k $ region
+the spectra of the jet type.",0804.3540v1
+2008-04-26,"Comments on gap anisotropy and nodal constant Fermi velocity in a superconductor, BSCCO","On the basis of both the inhomogeneity of a superconductor, BSCCO-2212, and
+the effect of measurement, we reveal that an anomalously large gap anisotropy
+known as evidence of dx2-y2-wave symmetry [Phys. Rev. Lett. 70 (1993) 1553] is
+not intrinsic, and that the constant Fermi velocity at node as an unsolved
+problem [Nature 423 (2003) 398] is due to the dx2-y2-wave insulator-metal
+transition.",0804.4209v1
+2008-05-13,Correlation of the HIghest Energy Cosmic Rays with the Supergalactic Plane,"We examine the anisotropy of the arrival directions of twenty seven ultra
+high energy cosmic rays detected by the Pierre Auger Collaboration. We confirm
+the anisotropy of the arrival directions of these events and find a significant
+correlation with the updated definition of the supergalactic plane at distances
+up to 70 Mpc, A Monte Carlo calculation of isotropic source distribution
+suggests a chance probability for isotropic event arrival direction
+distribution of 2-6$\times10^{-4}$.",0805.1746v2
+2008-05-14,Giant optical anisotropy in cylindrical self-assembled InAs/GaAs quantum rings,"Using a single-particle atomistic pseudopotential method followed by a
+many-particle configuration interaction method, we investigate the geometry,
+electronic structure and optical transitions of a self-assembled InAs/GaAs
+quantum ring (QR), changing its shape continously from a lens-shaped quantum
+dot (QD) to a nearly one dimensional ring. We find that the biaxial strain in
+the ring is strongly asymmetric in the plane perpendicular to the QR growth
+direction, leading to giant optical anisotropy.",0805.1962v1
+2008-05-14,Enhancement of evanescent waves inside media with extreme optical anisotropy,"Significant enhancement of evanescent spatial harmonics inside the slabs of
+media with extreme optical anisotropy is revealed. This phenomenon results from
+the pumping of standing waves and has the feature of being weakly sensitive to
+the material losses. Such characteristics may enable subwavelength imaging at
+considerable distances away from the objects.",0805.2080v3
+2008-06-05,Jet quenching and broadening: the transport coefficient $\hat{q}$ in an anisotropic plasma,"The jet quenching parameter $\hat{q}$ is analyzed for a quark jet propagating
+in an anisotropic plasma. The momentum anisotropy is calculated at high
+temperature of the underlying quark-gluon plasma. $\hat{q}$ is explicitly
+estimated in leading-logarithmic approximation by the broadening of the
+massless quark interacting via gluon exchange. A plasma instability is present.
+Strong indications are found that $\hat{q}$ is increasing with increasing
+anisotropy. Possible implications for the saturation scale $Q_s$ in $A-A$
+collisions are pointed out.",0806.0954v1
+2008-06-16,Spontaneous order in the highly frustrated spin-1/2 Ising-Heisenberg model on the triangulated Kagome lattice due to the Dzyaloshinskii-Moriya anisotropy,"The spin-1/2 Ising-Heisenberg model on the triangulated Kagome
+(triangles-in-triangles) lattice is exactly solved by establishing a precise
+mapping correspondence to the simple spin-1/2 Ising model on Kagome lattice. It
+is shown that the disordered spin liquid state, which otherwise occurs in the
+ground state of this frustrated spin system on assumption that there is a
+sufficiently strong antiferromagnetic intra-trimer interaction, is eliminated
+from the ground state by arbitrary but non-zero Dzyaloshinskii-Moriya
+anisotropy.",0806.2568v1
+2008-06-25,Anomalous Anisotropic Magnetoresistance in Heavy-Fermion PrFe4P12,"We have investigated the anisotropy of the magnetoresistance in the Pr-based
+HF compound PrFe4P12. The large anisotropy of effective mass and its strong
+field dependence have been confirmed by resistivity measurements. Particularly
+for H||[111], where the effective mass is most strongly enhanced, the non-Fermi
+liquid behavior has been observed. Also, we have found the angular dependence
+of the magnetoresistance sharply enhanced at H||[111], which is evidently
+correlated with both the non-Fermi liquid behavior and the high-field ordered
+state (B-phase).",0806.4047v1
+2008-07-16,Analytical solution of the equation of motion for a rigid domain wall in a magnetic material with perpendicular anisotropy,"This paper reports the solution of the equation of motion for a domain wall
+in a magnetic material which exhibits high magneto-crystalline anisotropy.
+Starting from the Landau-Lifschitz-Gilbert equation for field-induced motion,
+we solve the equation to give an analytical expression, which specifies the
+domain wall position as a function of time. Taking parameters from a Co/Pt
+multilayer system, we find good quantitative agreement between calculated and
+experimentally determined wall velocities, and show that high field uniform
+wall motion occurs when wall rigidity is assumed.",0807.2604v3
+2008-07-28,Gap anisotropy and universal pairing scale in a spin fluctuation model for cuprates,"We consider the evolution of d-wave pairing, mediated by nearly critical spin
+fluctuations, with the coupling strength. We show that the onset temperature
+for pairing, T*, smoothly evolves between weak and strong coupling, passing
+through a broad maximum at intermediate coupling. At strong coupling, T* is of
+order the magnetic exchange energy J. We argue that for all couplings, pairing
+is confined to the vicinity of the Fermi surface. We also find that thermal
+spin fluctuations only modestly reduce T*, even at criticality, but they
+substantially smooth the gap anisotropy. The latter evolves with coupling,
+being the largest at weak coupling.",0807.4404v1
+2008-08-11,Superhorizon Perturbations and the Cosmic Microwave Background,"Superhorizon perturbations induce large-scale temperature anisotropies in the
+cosmic microwave background (CMB) via the Grishchuk-Zel'dovich effect. We
+analyze the CMB temperature anisotropies generated by a single-mode adiabatic
+superhorizon perturbation. We show that an adiabatic superhorizon perturbation
+in a LCDM universe does not generate a CMB temperature dipole, and we derive
+constraints to the amplitude and wavelength of a superhorizon potential
+perturbation from measurements of the CMB quadrupole and octupole. We also
+consider constraints to a superhorizon fluctuation in the curvaton field, which
+was recently proposed as a source of the hemispherical power asymmetry in the
+CMB.",0808.1570v1
+2008-08-18,Quantum teleportation via a two-qubit Heisenberg XXZ chain-effects of anisotropy and magnetic field,"We study quantum teleportation via a two-qubit Heisenberg XXZ chain under an
+inhomogeneous magnetic field. We first consider entanglement teleportation, and
+then focus on the teleportation fidelity under different conditions. The
+effects of anisotropy and the magnetic field, both uniform and inhomogeneous,
+are discussed. We also find that, though entanglement teleportation does
+require an entangled quantum channel, a nonzero critical value of minimum
+entanglement is not always necessary.",0808.2406v1
+2008-08-21,On the role of pressure anisotropy for relativistic stars admitting conformal motion,"We investigate the spacetime of anisotropic stars admitting conformal motion.
+The Einstein field equations are solved using different ansatz of the surface
+tension. In this investigation, we study two cases in details with the
+anisotropy as: [1] $p_t = n p_r$ [2] $p_t - p_r = \frac{1}{8
+\pi}(\frac{c_1}{r^2} + c_2)$ where, n, $c_1$ and $c_2$ are arbitrary constants.
+The solutions yield expressions of the physical quantities like pressure
+gradients and the mass.",0808.2927v3
+2008-08-26,Spin-Orbit Integrated Ground State and Magnetic Anisotropy in Sr$_2$IrO$_4$,"We present a microscopic model for the anisotropic exchange interactions in
+Sr$_{2}$IrO$_{4}$. A direct construction of Wannier functions from
+first-principles calculations proves the $j_{\mathrm{eff}}$=1/2 character of
+the spin-orbit integrated states at the Fermi level. An effective
+$j_{\mathrm{eff}}$-spin Hamiltonian explains the observed weak ferromagnetism
+and anisotropy of antiferromagnetically ordered magnetic state, which arise
+naturally from the $j_{\mathrm{eff}}$=1/2 state with a rotation of IrO$_{6}$
+octahedra. It is suggested that Sr$_{2}$IrO$_{4}$ is a unique class of
+materials with effective exchange interactions in the spin-orbital Hilbert
+space.",0808.3491v2
+2008-08-30,Control of Domain Wall Position by Electrical Current in Structured Co/Ni Wire with Perpendicular Magnetic Anisotropy,"We report the direct observation of the current-driven domain wall (DW)
+motion by magnetic force microscopy in a structured Co/Ni wire with
+perpendicular magnetic anisotropy. The wire has notches to define the DW
+position. It is demonstrated that single current pulses can precisely control
+the DW position from notch to notch with high DW velocity of 40 m/s.",0809.0047v1
+2008-10-31,Optical Anisotropy of Electronic Excitations in Elliptical Quantum Dots,"The authors report that anisotropic confining potentials in laterally-coupled
+semiconductor quantum dots (QDs) have large impacts in optical transitions and
+energies of inter-shell collective electronic excitations. The observed
+anisotropies are revealed by inelastic light scattering as a function of the
+in-plane direction of light polarization and can be finely controlled by
+modifying the geometrical shape of the QDs. These experiments show that the
+tuning of the QD confinement potential offers a powerful method to manipulate
+electronic states and far-infrared inter-shell optical transitions in quantum
+dots.",0810.5649v1
+2008-11-04,Three-Component Fermi Gas in a one-dimensional Optical Lattice,"We investigate the effect of the anisotropy between the s-wave scattering
+lengths of a three-component atomic Fermi gas loaded into a one-dimensional
+optical lattice. We find four different phases which support trionic
+instabilities made of bound states of three fermions. These phases distinguish
+themselves by the relative phases between the 2$k_F$ atomic density waves
+fluctuations of the three species. At small enough densities or strong
+anisotropies we give further evidences for a decoupling and the stabilization
+of more conventional BCS phases. Finally our results are discussed in light of
+a recent experiment on $^{6}$Li atoms.",0811.0555v2
+2008-11-05,Quantum Phase Diagram and Excitations for the One-Dimensional S=1 Heisenberg Antiferromagnet with Single-Ion Anisotropy,"We investigate the zero-temperature phase diagram of the one-dimensional S=1
+Heisenberg antiferromagnet with single-ion anisotropy. By employing high-order
+series expansions and quantum Monte Carlo simulations we obtain accurate
+estimates for the critical points separating different phases in the quantum
+phase diagram. Additionally, excitation spectra and gaps are obtained.",0811.0646v2
+2008-11-07,Translational Invariance and the Anisotropy of the Cosmic Microwave Background,"Primordial quantum fluctuations produced by inflation are conventionally
+assumed to be statistically homogeneous, a consequence of translational
+invariance. In this paper we quantify the potentially observable effects of a
+small violation of translational invariance during inflation, as characterized
+by the presence of a preferred point, line, or plane. We explore the imprint
+such a violation would leave on the cosmic microwave background anisotropy, and
+provide explicit formulas for the expected amplitudes $<a_{lm}a_{l'm'}^*>$ of
+the spherical-harmonic coefficients.",0811.1086v3
+2008-11-11,Anisotropy due to Brans-Dicke Theory,"It is well known that the viscous Bianchi type-I metric of the Kasner form is
+not able to describe an anisotropic universe, which satisfies the second law of
+thermodynamics and the dominant energy condition in Einstein's theory of
+gravity. We investigate this problem in Brans-Dicke theory of gravity using the
+Bianchi type-I metric with the perfect fluid. We show that it is possible to
+have the dominant energy condition and the growth of entropy in this model.
+Also we apply this model to explain the anomaly concerning the low quadrupole
+amplitude of the angular power spectrum of the temperature anisotropy observed
+in WMAP data.",0811.1643v1
+2008-11-13,Effects of anisotropy on optimal dense coding,"We study optimal dense coding with thermal entangled states of a two-qubit
+anisotropic \emph{XXZ} model and a Heisenberg model with Dzyaloshinski-Moriya
+(DM) interactions. The DM interaction is another kind of anisotropic
+antisymmetric exchange interaction. The effects of these two kinds of
+anisotropies on dense coding are studied in detail for both the
+antiferromagnetic and ferromagnetic cases. For the two models, we give the
+conditions that the parameters of the models have to satisfy for a valid dense
+coding. We also found that even though there is entanglement, it is unavailable
+for our optimal dense coding, which is the same as entanglement teleportation.",0811.2017v1
+2008-11-13,Magnetoelastic coupling in BaTiO3-based multiferroic structures,"Analytical expressions for the magnetoelastic anisotropy constants of cubic
+magnetic systems are derived for rectangular and oblique distortions
+originating from epitaxial growth on substrates with lower crystal symmetry. In
+particular, the temperature variation of the magnetic properties of magnetic
+films grown on barium titanate (BaTiO3) substrates are explained in terms of
+strain-induced magnetic anisotropies caused by the temperature dependent phase
+transitions of BaTiO3. Our results quantify the experimental observations in
+ferromagnet/\bto-based structures, which have been proposed as templates for
+magnetoelectric composite heterostructures.",0811.2146v1
+2008-11-26,Gate control of a quantum dot single-electron spin in realistic confining potentials: anisotropy effects,"Among recent proposals for next-generation, non-charge-based logic is the
+notion that a single electron can be trapped and its spin can be manipulated
+through the application of gate potentials. In this paper, we present numerical
+simulations of such spins in single electron devices for realistic (asymmetric)
+confining potentials in two-dimensional electrostatically confined quantum
+dots. Using analytical and numerical techniques we show that breaking the
+in-plane rotational symmetry of the confining potential leads to a significant
+effect on the tunability of the g-factor with applied gate potentials. In
+particular, anisotropy extends the range of tunability to larger quantum dots.",0811.4201v1
+2008-12-10,Magnetic Bianchi I Universe in Loop Quantum Cosmology,"We examine the dynamical consequences of homogeneous cosmological magnetic
+fields in the framework of loop quantum cosmology. We show that a big-bounce
+occurs in a collapsing magnetized Bianchi I universe, thus extending the known
+cases of singularity-avoidance. Previous work has shown that perfect fluid
+Bianchi I universes in loop quantum cosmology avoid the singularity via a
+bounce. The fluid has zero anisotropic stress, and the shear anisotropy in this
+case is conserved through the bounce. By contrast, the magnetic field has
+nonzero anisotropic stress, and shear anisotropy is not conserved through the
+bounce. After the bounce, the universe enters a classical phase. The addition
+of a dust fluid does not change these results qualitatively.",0812.1889v1
+2008-12-13,A Novel Temperature-Induced Magnetization Transition in Pt/Co/Pt Sandwiches,"It is found in the Pt/Co/Pt(111) sandwiches that perpendicular magnetic
+anisotropy weakens associated with the dramatic magnetization enhancement as
+the temperature decreases below a critical temperature, T_cri, which increases
+with the Pt overlayer thickness t_Pt. For the sandwich with enough thick Pt
+overlayer, it trends to an unusual state with weak perpendicular magnetic
+anisotropy in the absence of obvious easy direction behavior at low
+temperature. It suggests that Pt is more significantly polarized in the film
+with thicker Pt overlayer. The results reveal the strong influence of both
+thick nonmagnetic coverage and temperature on the electronic structure of the
+Pt/Co/Pt(111) sandwich.",0812.2512v1
+2009-01-11,Magnetic soliton transport over topological spin texture in chiral helimagnet with strong easy-plane anisotropy,"We show the existence of an isolated soliton excitation over the topological
+ground state configuration in chiral helimagnet with the Dzyaloshinskii-Moryia
+exchange and the strong easy-plane anisotropy. The magnetic field perpendicular
+to the helical axis stabilizes the kink crystal state which plays a role of
+""topological protectorate"" for the traveling soliton with a definite
+handedness. To find new soliton solution, we use the B\""{a}cklund
+transformation technique. It is pointed out that the traveling soliton carries
+the magnon density and a magnetic solition transport may be realized.",0901.1423v1
+2009-01-14,Spin-1 Heisenberg antiferromagnetic chain with exchange and single-ion anisotropies,"Using density matrix renormalization group calculations, ground state
+properties of the spin-1 Heisenberg chain with exchange and single-ion
+anisotropies in an external field are studied. Our findings confirm and refine
+recent results by Sengupta and Batista, Physical Review Letters 99, 217205
+(2007) (2007), on the same model applying Monte Carlo techniques. In
+particular, we present evidence for two types of biconical (or supersolid) and
+for two types of spin-flop (or superfluid) structures. Basic features of the
+quantum phase diagram may be interpreted qualitatively in the framework of
+classical spin models.",0901.2081v2
+2009-01-15,On Anisotropy of Ultra-High Energy Cosmic-Rays,"We briefly summarize our study on anisotropy of Ultra-High Energy Cosmic-Rays
+(UHECRs), in which we define a statistics that measures the correlation between
+UHECRs and Large Scale Structure (LSS). We also comment here on recently
+published paper by Koers and Tinyakov that compared our statistics to improved
+KS statistics.",0901.2256v2
+2009-01-21,"Lateral magnetic anisotropy superlattice out of a single (Ga,Mn)As layer","We use lithographically induced strain relaxation to periodically modulate
+the magnetic anisotropy in a single (Ga,Mn)As layer. This results in a lateral
+magnetoresistance device where two non-volatile magnetic states exist at zero
+external magnetic field with resistances resulting from the orientation of two
+lithographically defined regions in a single and contiguous layer.",0901.3210v1
+2009-03-12,Simulation of a spin-wave instability from atomistic spin dynamics,"We study the spin dynamics of a Heisenberg model at finite temperature in the
+presence of an external field or a uniaxial anisotropy. For the case of the
+uniaxial anisotropy our simulations show that the macro moment picture breaks
+down. An effect which we refer to as a spin-wave instability (SWI) results in a
+non-dissipative Bloch-Bloembergen type relaxation of the macro moment where the
+size of the macro moment changes, and can even be made to disappear. This
+relaxation mechanism is studied in detail by means of atomistic spin dynamics
+simulations.",0903.2186v1
+2009-03-25,On the Experimental Substantiation of Anisotropy of Inertial Mass of Body in the Earth Gravitation Field,"On the basis of the field concept of gravitation and gravitational analogue
+of the Faradays induction law the difference of inertial mass of a body at its
+accelerated movement in horizontal and vertical directions relative to the
+Earth is shown. For an illustration of such a distinction the results of
+comparison of a motion of balance mechanical watch at horizontal and vertical
+orientations of balance axis are given. The expediency of statement of
+precision mechanical experiments with measurement of anisotropy of the inertial
+mass is noted, allowing to estimate the validity of the field approach in the
+description of gravitation.",0903.4433v1
+2009-03-30,Lecture notes on the physics of cosmic microwave background anisotropies,"We review the theory of the temperature anisotropy and polarization of the
+cosmic microwave background (CMB) radiation, and describe what we have learned
+from current CMB observations. In particular, we discuss how the CMB is being
+used to provide precise measurements of the composition and geometry of the
+observable universe, and to constrain the physics of the early universe. We
+also briefly review the physics of the small-scale CMB fluctuations generated
+during and after the epoch of reionization, and which are the target of a new
+breed of arcminute-resolution instruments.",0903.5158v1
+2009-03-30,Origin of Gap Anisotropy in Spin Fluctuation Models of the Fe-pnictides,"We discuss the large gap anisotropy found for the A1g (s-wave) state in RPA
+spin-fluctuation and functional renormalization group calculations and show how
+the simple arguments leading to isotropic sign-switched s-wave states in these
+systems need to be supplemented by a consideration of pair scattering within
+Fermi surface sheets and between the individual electron sheets as well. In
+addition, accounting for the orbital makeup of the states on the Fermi surface
+is found to be crucial.",0903.5216v1
+2009-04-01,Current-induced microwave excitation of a domain wall confined in a magnetic wire with bi-axial anisotropy,"We studied the current-induced magnetization dynamics of a domain wall
+confined in a magnetic wire with bi-axial anisotropy. We showed that above the
+threshold current density, breathing-mode excitation, where the thickness of
+the domain wall oscillates, is induced by spin-transfer torque. We found that
+the breathing-mode can be applied as a source of microwave oscillation because
+the resistance of the domain wall is a function of the domain wall thickness.
+In a current sweep simulation, the frequency of the breathing-mode exhibits
+hysteresis because of the confinement.",0904.0044v1
+2009-05-14,Plasticity-induced structural anisotropy of silica glass,"Amorphous silica density at ambient pressure is known to depend on thermal
+history (through the quenching rate) but also, at room temperature, on the
+maximum pressure applied in the past. Here we show that beyond density, a
+mechanical loading can endow the structure with an orientational order.
+Molecular dynamics simulations show evidence that amorphous silica develops a
+permanent anisotropic structure after extended shear plastic flow. This
+anisotropy which survives for an unstressed specimen is revealed markedly by
+the fabric tensor computed over the Si-O-Si orientations, albeit the SiO4
+tetrahedra microstructure remains mostly unaltered.",0905.2319v1
+2009-05-15,Planar superconductor/ferromagnet hybrids: Anisotropy of resistivity induced by magnetic templates,"We investigated experimentally the transport properties of a superconducting
+cross-shaped aluminium microbridge fabricated on top of ferromagnetic BaFe12O19
+single crystal. It was demonstrated that a one-dimensional domain structure in
+the ferromagnetic substrate can induce the formation of superconducting
+channels above magnetic domains. This leads to a giant anisotropy of
+resistivity of the superconducting bridge, caused by the appearance of
+continuous paths of supercurrents flowing along domain walls.",0905.2590v1
+2009-05-27,Magnetic response of magnetic molecules with non-collinear local d-tensors,"Investigations of molecular magnets are driven both by prospective
+applications in future storage technology or quantum computing as well as by
+fundamental questions. Nowadays numerical simulation techniques and computer
+capabilities make it possible to investigate spin Hamiltonians with realistic
+arrangements of local anisotropy tensors. In this contribution I will discuss
+the magnetic response of a small spin system with special emphasis on
+non-collinear alignments of the local anisotropy axes.",0905.4375v2
+2009-05-28,Anisotropy of the interface tension of the three-dimensional Ising model,"We determine the interface tension for the 100, 110 and 111 interface of the
+simple cubic Ising model with nearest-neighbour interaction using novel
+simulation methods. To overcome the droplet/strip transition and the droplet
+nucleation barrier we use a newly developed combination of the multimagnetic
+algorithm with the parallel tempering method. We investigate a large range of
+inverse temperatures to study the anisotropy of the interface tension in
+detail.",0905.4569v1
+2009-06-12,Six-fold configurational anisotropy and magnetic reversal in nanoscale Permalloy triangles,"Six-fold configurational anisotropy was studied in Permalloy triangles, in
+which the shape symmetry order yields two energetically non-degenerate
+micromagnetic configurations of the spins, the so-called ""Y"" and ""buckle""
+states. A twelve pointed switching astroid was measured using magneto-optical
+experiments and successfully reproduced numerically, with different polar
+quadrants identified as specific magnetic transitions, thereby giving a
+comprehensive view of the magnetic reversal in these structures. A detailed
+analysis highlighted the necessity to include the physical rounding of the
+structures in the simulations to account for the instability of the Y state.",0906.2322v1
+2009-06-22,Anisotropy in the sky distributions of the short and intermediate gamma-ray bursts: Breakdown of the cosmological principle?,"After the discovery of the anisotropy in the sky-distribution of intermediate
+gamma-ray bursts recently also the distribution of the short gamma-ray bursts
+is proven to be anisotropic. The impact of these behaviors on the validity of
+the cosmological principle is shortly discussed.",0906.4034v1
+2009-07-26,Nematic Anchoring on Carbon Nanotubes,"A dilute suspension of carbon nanotubes (CNTs) in a nematic liquid crystal
+(LC) does not disturb the LC director. Due to a strong LC-CNT anchoring energy
+and structural symmetry matching, CNT long axis follows the director field,
+possessing enhanced dielectric anisotropy. This strong anchoring energy
+stabilizes local pseudo-nematic domains, resulting in non-zero dielectric
+anisotropy in the isotropic phase. These anisotropic domains respond to
+external electric fields and show intrinsic frequency response. The presence of
+these domains makes the isotropic phase field-responsive, giving rise to a
+large dielectric hysteresis effect.",0907.4455v2
+2009-09-10,Circumstantial evidence for a non-Maxwellian plasma from femtosecond laser-matter interaction,"We study ion acceleration mechanisms in laser-plasma interactions using
+neutron spectroscopy. We consider different types of ion-collision mechanisms
+in the plasma, which cause the angular anisotropy of the observed neutron
+spectra. These include the collisions between an ion in the plasma and an ion
+in the target, and the collisions between two ions in the hot plasma. By
+analyzing the proton spectra, we suggest that the laser-generated plasma
+consists of at least two components, one of which collectively accelerated and
+can also produce anisotropy in the angular distribution of fusion neutrons.",0909.2048v1
+2009-09-25,Tunable steady-state domain wall oscillator with perpendicular magnetic anisotropy,"We theoretically study domain wall oscillations upon the injection of a dc
+current through a geometrically constrained wire with perpendicular magnetic
+anisotropy. The oscillation frequency spectrum can be tuned by the injected
+current density, but additionally by the application of an external magnetic
+field independent of the power. The results of analytical calculations are
+supported by micromagnetic simulations based on the Landau-Lifshitz-Gilbert
+equation. The simple concept of our localized steady-state oscillator might
+prove useful as a nanoscale microwave generator with possible applications in
+telecommunication or for rf-assisted writing in magnetic hard drives.",0909.4733v1
+2009-09-30,Collapse of triaxial bright solitons in atomic Bose-Einstein condensates,"We study triaxial bright solitons made of attractive Bose-condensed atoms
+characterized by the absence of confinement in the longitudinal axial direction
+but trapped by an anisotropic harmonic potential in the transverse plane. By
+numerically solving the three-dimensional Gross-Pitaevskii equation we
+investigate the effect of the transverse trap anisotropy on the critical
+interaction strength above which there is the collapse of the condensate. The
+comparison with previous predictions [Phys. Rev. A {\bf 66}, 043619 (2002)]
+shows significant differences for large anisotropies.",0910.0035v1
+2009-10-02,Single-Species Weibel Instability of Radiationless Plasma,"A Particle-in-Cell (PIC) numerical simulation of the electron Weibel
+instability is applied in a frame of Darwin (radiationless) approximation of
+the self-consistent fields of sparse plasma. As a result, we were able to
+supplement the classical picture of the instability and, in particular, to
+obtain the dependency of the basic characteristics (the time of development and
+the maximum field energy) of the thermal anisotropy parameter, to trace the
+dynamic restructuring of current filaments accompanying the nonlinear stage of
+the instability and to trace in detail the evolution of the initial anisotropy
+of the electron component of plasma.",0910.0361v2
+2009-11-10,Direct and inverse measurement of thin films magnetostriction,"Two techniques of measurements of thin film magnetostriction are compared:
+direct, when changes of the substrate curvature caused by the film
+magnetization are controlled, and inverse (""indirect""), when the modification
+of the magnetic anisotropy induced by the substrate deformation (usually
+bending) is measured. We demonstrate how both the elastic strength of the
+substrate and the effective magneto-mechanical coupling between the substrate
+deformation and magnetic anisotropy of the film depend on different conditions
+of bending. Equations to be used for magnetostriction value determination in
+typical cases are given and critical parameters for the corresponding
+approximations are identified.",0911.1914v1
+2009-11-14,Rotational States of Magnetic Molecules,"We study a magnetic molecule that exhibits spin tunneling and is free to
+rotate about its anisotropy axis. Exact low-energy eigenstates of the molecule
+that are superpositions of spin and rotational states are obtained. We show
+that parameter $\alpha = 2(\hbar S)^2/(I\Delta)$ determines the ground state of
+the molecule. Here $\hbar S$ is the spin, $I$ is the moment of inertia, and
+$\Delta$ is the tunnel splitting. The magnetic moment of the molecule is zero
+at $\alpha < \alpha_c = [1-1/(2S)^{2}]^{-1}$ and non-zero at $\alpha >
+\alpha_c$. At $\alpha \to \infty$ the spin of the molecule localizes in one of
+the directions along the anisotropy axis.",0911.2810v1
+2009-12-21,Polarization dependent spontaneous-emission rate of single quantum dots in photonic crystal membranes,"We have measured the variation of the spontaneous emission rate with
+polarization for self-assembled single quantum dots in two-dimensional photonic
+crystal membranes. We observe a maximum anisotropy factor of 6 between the
+decay rates of the two bright exciton states. This large anisotropy is
+attributed to the substantially different projected local density of optical
+states for differently oriented dipoles in the photonic crystal.",0912.4109v2
+2009-12-29,On asimuthal anisotropy in fragmentation of classical relativistic string,"A fragmenting relativistic string is widely used for modelling particle
+production via quark-gluon strings formed in hadron inelastic interactions of
+high energies. In this note we focus on motion and fragmentation of
+relativistic string with non-zero transverse separation of its ends and study
+this scenario as a possible mechanism bringing anisotropy into the asimuthal
+angle disribution of produced particles in inelastic interactions of hadrons.",0912.5377v1
+2010-01-11,Nonlocal effects on magnetism in the diluted magnetic semiconductor Ga_{1-x}Mn_{x}As,"The magnetic properties of the diluted magnetic semiconductor
+Ga_{1-x}Mn_{x}As are studied within the dynamical cluster approximation. We use
+the k-dot-p Hamiltonian to describe the electronic structure of GaAs with
+spin-orbit coupling and strain effects. We show that nonlocal effects are
+essential for explaining the experimentally observed transition temperature and
+saturation magnetization. We also demonstrate that the cluster anisotropy is
+very strong and induces rotational frustration and a cube-edge direction
+magnetic anisotropy at low temperature. With this, we explain the
+temperature-driven spin reorientation in this system.",1001.1716v1
+2010-01-29,Variations of decay rates of radio-active elements and their connections with global anisotropy of physical space,"The analysis of correlations between fluctuations of alpha- and beta-decay
+rates for different radio-active elements is carried out. These fluctuations
+exceed significantly errors of measurements in many cases. They have the
+periodical character and reveal definite spatial directions. We suggest that
+the observed fluctuations are caused by the unique physical reason connected
+with the global anisotropy of physical space and by the new force.",1001.5383v1
+2010-02-26,25 years of Cosmic Microwave Background research at INPE,"This article is a report of 25 years of Cosmic Microwave Background
+activities at INPE. Starting from balloon flights to measure the dipole
+anisotropy caused by the Earth's motion inside the CMB radiation field, whose
+radiometer was a prototype of the DMR radiometer on board COBE satellite,
+member of the group cross the 90s working both on CMB anisotropy and foreground
+measurements. In the 2000s, there was a shift to polarization measurements and
+to data analysis, mostly focusing on map cleaning, non-gaussianity studies and
+foreground characterization.",1002.4902v1
+2010-02-28,Asymmetric Beams and CMB Statistical Anisotropy,"Beam asymmetries result in statistically-anisotropic cosmic microwave
+background (CMB) maps. Typically, they are studied for their effects on the CMB
+power spectrum, however they more closely mimic anisotropic effects such as
+gravitational lensing and primordial power asymmetry. We discuss tools for
+studying the effects of beam asymmetry on general quadratic estimators of
+anisotropy, analytically for full-sky observations as well as in the analysis
+of realistic data. We demonstrate this methodology in application to a
+recently-detected 9 sigma quadrupolar modulation effect in the WMAP data,
+showing that beams provide a complete and sufficient explanation for the
+anomaly.",1003.0198v2
+2010-03-01,Anisotropy of the Stone-Wales Defect and Warping of Graphene Nano-ribbons: A First-principles Analysis,"Stone-Wales (SW) defects, analogous to dislocations in crystals, play an
+important role in mechanical behavior of $sp^2$-bonded carbon based materials.
+Here, we show using first-principles calculations that a marked anisotropy in
+the interaction among the SW defects has interesting consequences when such
+defects are present near the edges of a graphene nano-ribbon: depending on
+their orientation with respect to edge, they result in compressive or tensile
+stress, and the former is responsible to depression or warping of the graphene
+nano-ribbon. Such warping results in delocalization of electrons in the defect
+states.",1003.0479v1
+2010-06-01,Geometric signature of reversal modes in ferromagnetic nanowires,"Magnetic nanowires are a good platform to study fundamental processes in
+Magnetism and have many attractive applications in recording such as
+perpendicular storage and in spintronics such as non-volatile magnetic memory
+devices (MRAM) and magnetic logic devices. In this work, nanowires are used to
+study magnetization reversal processes through a novel geometric approach.
+Reversal modes imprint a definite signature on a parametric curve representing
+the locus of the critical switching field. We show how the different modes
+affect the geometry of this curve depending on the nature of the anisotropy
+(uniaxial or cubic anisotropy), demagnetization and exchange effects. The
+samples we use are electrochemically grown Nickel and Cobalt nanowires.",1006.0105v1
+2010-06-08,Strong-interaction approximation for transfer matrix method,"Using transfer-matrix method a correspondence between $2D$ classical spin
+systems ($2D$ Ising model and six-vertex model) and $1D$ quantum spin systems
+is considered. We find the transfer matrix in two limits - in a well-known
+strong-anisotropy limit and a novel strong-interaction limit. In contrast to
+the usual strong-anisotropy approximation, within the strong-interaction
+approximation we take into account the non-commutativity of transfer-matrix
+components. The latter approximation is valid for low temperatures or strong
+interaction in one spatial dimension. We observe that the Hamiltonian of the
+corresponding quantum chains contains multispin interactions.",1006.1608v1
+2010-06-08,Horava-Lifshitz modifications of the Casimir effect,"We study the modifications induced by spacetime anisotropy on the Casimir
+effect in the case of two parallel plates. Nonperturbative and perturbative
+regimes are analyzed. In the first case the Casimir force either vanishes or it
+reverses its direction which, in any case, makes the proposal untenable. On the
+other hand, the perturbative model enables us to incorporate appropriately the
+effects of spacetime anisotropy.",1006.1635v1
+2010-07-13,Current-induced exchange switching magnetic junctions with cubic anisotropy of the free layer,"The stability is analyzed of the equilibrium configurations of a magnetic
+junction with a free layer that has cubic symmetry and two anisotropy axes in
+the layer plane. Different variants of the switching between various
+configurations are considered. A possibility is shown of the substantial
+lowering of the threshold current density needed for the switching. Numerical
+simulation is made of the switching dynamics for various configurations.",1007.2097v1
+2010-07-16,"Equation of State, Stability, Anisotropy and Nonlinear Elasticity of Diamond-Cubic (ZB) Silicon by Phonon Imaging at High Pressure","Experimental phonon imaging in diamond anvils cell is demonstrated to be an
+adequate tool to extract the complete set of elastic constants of
+single-crystalline silicon up to the ZB$\rightarrow \beta-$Sn transition (10
+GPa). Contrary to what was commonly admitted, we demonstrate that the
+development of the strain-energy density in terms of strains cannot be stopped,
+for silicon, after the terms containing the third-order elastic constants.
+Nonlinear elasticity, degree of anisotropy and pressure-induced mechanical
+stability of the cubic silicon structure are thus revisited and investigated in
+more detail.",1007.2730v1
+2010-08-02,Elliptic flow from color strings,"It is shown that the elliptic flow can be successfully described in the color
+string picture with fusion and percolation provided anisotropy of particle
+emission from the fused string is taken into account. Two possible sources of
+this anisotropy are considered, propagation of the string in the transverse
+plane and quenching of produced particles in the strong color field of the
+string. Calculations show that the second source gives an overwhelming
+contribution to the flow at accessible energies.",1008.0245v1
+2010-08-05,Anisotropic magnetocaloric effect in all-ferromagnetic (La0.7Sr0.3MnO3/SrRuO3) superlattices,"We exploit the magnetic interlayer coupling in La0.7Sr0.3MnO3/SrRuO3
+superlattices to realize a crossover between inverse and conventional magnetic
+entropy changes. Our data reveal a strong anisotropic nature of the
+magnetocaloric effect due to the magnetic anisotropy of the superlattice.
+Therefore, artificial superlattices built from ferromagnetic materials that can
+be used to alter the magnetic structure as well as the magnetic anisotropy,
+could also be utilized for tuning the magnetocaloric properties, which may open
+a constructive approach for magnetic refrigeration applications.",1008.1041v1
+2010-08-26,Two-electron entanglement in elliptically deformed quantum dots,"Entropic entanglement measures of a two-dimensional system of two
+Coulombically interacting particles confined in an anisotropic harmonic
+potential are discussed in dependence on the anisotropy and the interaction
+strength. The harmonic approximation appears exact in the strong interaction
+limit, allowing determination of the asymptotic expression for the linear
+entropy. Entanglement properties are dramatically influenced by the anisotropy
+of the confining potential in the strong-correlation regime.",1008.4605v1
+2010-09-11,Anisotropic charge transport in non-polar GaN QW: polarization induced charge and interface roughness scattering,"Charge transport in GaN quantum well (QW) devices grown in non-polar
+direction has been theoretically investigated . Emergence of anisotropic line
+charge scattering mechanism originating as a result of anisotropic rough
+surface morphology in conjunction with in-plane built-in polarization has been
+proposed. It has shown that in-plane growth anisotropy leads to large
+anisotropic carrier transport at low temperatures. At high temperatures, this
+anisotropy in charge transport is partially washed out by strong isotropic
+optical phonon scattering in GaN QW.",1009.2156v2
+2010-09-22,Shape anisotropy of polymers in disordered environment,"We study the influence of structural obstacles in a disordered environment on
+the size and shape characteristics of long flexible polymer macromolecules. We
+use the model of self-avoiding random walks on diluted regular lattices at the
+percolation threshold in space dimensions d=2, 3. Applying the Pruned-Enriched
+Rosenbluth Method (PERM), we numerically estimate rotationally invariant
+universal quantities such as the averaged asphericity A_d and prolateness S of
+polymer chain configurations. Our results quantitatively reveal the extent of
+anisotropy of macromolecules due to the presence of structural defects.",1009.4358v2
+2010-09-28,Spin-orbit anisotropy measured using ballistic spin resonance,"Spin relaxation can be greatly enhanced in narrow channels of two-dimensional
+electron gas due to ballistic spin resonance, which is mediated by spin-orbit
+interaction for trajectories that bounce rapidly between channel walls. The
+channel orientation determines which momenta affect the relaxation process, so
+comparing relaxation for two orientations provides a direct determination of
+spin-orbit anisotropy. Electrical measurements of pure spin currents are shown
+to reveal an order of magnitude stronger relaxation for channels fabricated
+along the [110] crystal axis in a GaAs electron gas compared to [-110]
+channels, believed to result from interference between structural and bulk
+inversion asymmetries.",1009.5702v1
+2010-09-29,Spin quadrupoletronics: moving spin anisotropy around,"We show that spin anisotropy can be transferred to an isotropic system by
+transport of spin quadrupole moment. We derive the quadrupole moment current
+and continuity equation and study a high-spin valve structure consisting of two
+ferromagnets coupled to a quantum dot probing an impurity spin. The quadrupole
+back-action on their coupled spin results in spin torques and anisotropic spin
+relaxation which do not follow from standard spin current considerations. We
+demonstrate the detection of the impurity spin by charge transport and its
+manipulation by electric fields.",1009.5874v2
+2010-10-19,Third-order Elsässer moments in axisymmetric MHD turbulence,"Incompressible MHD turbulence is investigated under the presence of a uniform
+magnetic field $\bb0$. Such a situation is described in the correlation space
+by a divergence relation which expresses the statistical conservation of the
+Els\""asser energy flux through the inertial range. The ansatz is made that the
+development of anisotropy, observed when $B_0$ is strong enough, implies a
+foliation of space correlation. A direct consequence is the possibility to
+derive a vectorial law for third-order Els\""asser moments which is parametrized
+by the intensity of anisotropy. We use the so-called critical balance
+assumption to fix this parameter and find a unique expression.",1010.3823v1
+2010-10-21,The effect of Dzyaloshinskii-Moriya interactions on the phase diagram and magnetic excitations of SrCu2(BO3)2,"The orthogonal dimer structure in the SrCu2(BO3)2 spin-1/2 magnet provides a
+realization of the Shastry-Sutherland model. Using a dimer-product variational
+wave function, we map out the phase diagram of the Shastry-Sutherland model
+including anisotropies. Based on the variational solution, we construct a
+bond-wave approach to obtain the excitation spectra as a function of magnetic
+field. The characteristic features of the experimentally measured neutron and
+ESR spectra are reproduced, like the anisotropy induced zero field splittings
+and the persistent gap at higher fields.",1010.4476v2
+2010-10-23,High spin polarization in epitaxial films of ferrimagnetic Mn3Ga,"Ferrimagnetic Mn3Ga exhibits a unique combination of low saturation
+magnetization (Ms = 0.11 MA m-1) and high perpendicular anisotropy with a
+uniaxial anisotropy constant of Ku = 0.89 MJ m-3. Epitaxial c-axis films
+exhibit spin polarization as high as 58%, measured using point contact Andreev
+reflection. These epitaxial films will be able to support thermally stable
+sub-10 nm bits for spin transfer torque memories.",1010.4872v1
+2010-10-27,CoIr-carbon complexes with magnetic anisotropies larger than 0.2 eV: a density-functional-theory prediction,"We report a density-functional study of the heteronuclear CoIr dimer adsorbed
+on benzene or graphene. In either case CoIr prefers an upright position above
+the center of a carbon hexagon with the Co atom next to it. The Ir atom stays
+away from the carbon ring and thus preserves its free-atom-like properties.
+This results in a very large magnetic anisotropy of more than 0.2 eV per dimer.
+So high a value should suffice for long-term data storage at the temperature of
+liquid nitrogen.",1010.5663v1
+2010-11-12,"Comprehensive transport studies of anisotropy and ordering phenomena in quasi-one-dimensional (TMTTF)2X salts (X = PF6, AsF6, SbF6; BF4, ClO4, ReO4)","The temperature dependent dc resistivity of the quasi-one-dimensional organic
+salts (TMTTF)2X ( X = PF6, AsF6, SbF6; BF4, ClO4, ReO4) has been measured in
+all three crystal directions in order to investigate anisotropy, localization
+effects, charge and anion ordering phenomena at low temperatures. For all
+compounds and directions we extract the transport mechanisms in different
+regimes. The data are thoroughly analyzed, related to structural properties,
+and extensively discussed in view of previous studies and latest theories. It
+becomes apparent that the anions have a severe influence on the physical
+properties of the TMTTF salts.",1011.2856v1
+2010-11-18,Lost and found: The missing diabolical points in the Fe$_8$ molecular magnet,"Certain diabolical points in the tunneling spectrum of the single-molecule
+magnet Fe$_8$ were previously believed to be have been eliminated as a result
+of a weak fourth-order anisotropy. As shown by Bruno, this is not so, and the
+points are only displaced in the magnetic field space along the medium
+anisotropy direction. The previously missing points are numerically located by
+following the lines of the Berry curvature. The importance of an experimental
+search for these rediscovered points is discussed.",1011.4326v2
+2010-11-19,"Anisotropic spin fluctuations and superconductivity in ""115'' heavy fermion compounds: 59Co NMR study in PuCoGa5","We report results of $^{59}$Co nuclear magnetic resonance measurements on a
+single crystal of superconducting PuCoGa5 in its normal state. The nuclear
+spin-lattice relaxation rates and the Knight shifts as a function of
+temperature reveal an anisotropy of spin fluctuations with finite wave vector
+q. By comparison with the isostructural members, we conclude that
+antiferromagnetic XY-type anisotropy of spin fluctuations plays an important
+role in mediating superconductivity in these heavy fermion materials.",1011.4466v1
+2010-11-29,Measuring the thermalization time,"A new method of measuring the pressure anisotropy in the early stage of
+heavy-ion collisions is discussed. It is shown that the transverse momentum
+spectra, elliptic flow and interferometry radii are not sensitive to the early
+anisotropy. We propose the directed flow as a measure of the early transverse
+and longitudinal pressures. Calculations indicate that the transverse and
+longitudinal pressures equilibrate in less than 0.25 fm/c.",1011.6210v1
+2010-12-01,Size dependent electric voltage-controlled magnetic anisotropy in multiferroic heterostructures: Interface-charge and strain co-mediated magnetoelectric coupling,"We present a phenomenological scheme to study the size-dependent electric
+voltage-controlled magnetic anisotropy in ferromagnetic (FM)/ferroelectric (FE)
+heterostructures. The FM layers are either metallic Fe(001), Ni(001), Co(0001),
+or half-metallic (La, Sr)MnO3 films. Two magnetoelectric mechanisms, i.e.,
+interface-charge and strain-mediated couplings, are considered. We show that
+the interface-charge mediated coupling is the main mechanism for the
+magnetoelectic coupling when the FM film thickness is below a certain
+transition thickness dtr while the strain-mediated coupling dominates above
+dtr.",1012.0088v1
+2010-12-08,Directional Anisotropy of Swift Gamma-Ray Bursts,"Swift satellite measurements contributed substantially to the gamma-ray burst
+(GRB) redshift observations through fast slewing to the source of the GRBs.
+Still, a large number of bursts are without redshift. We study the celestial
+distribution of bursts with various methods and compare them to a random
+catalog using Monte-Carlo simulations. We find an anisotropy in the
+distribution of the intermediate class of bursts and find that the short and
+long population are distributed isotropically.",1012.1757v2
+2010-12-22,Transport properties of the new Fe-based superconductor KxFe2Se2 (Tc = 33 K),"We synthesized the new Fe-based superconductor K0.8Fe2Se2 single crystals.
+The obtained single crystal exhibited a sharp superconducting transition, and
+the onset and zero-resistivity temperature was estimated to be 33 and 31.8 K,
+respectively. A high upper critical field of 192 T was obtained. Anisotropy of
+superconductivity of K0.8Fe2Se2 was ~3.6. Both the high upper critical field
+and comparably low anisotropy are advantageous for the application under high
+magnetic field.",1012.4950v1
+2011-01-06,Towards a first observation of magneto-electric directional anisotropy and linear birefringence in gases,"In this contribution to PSAS'2010 we report on recent progress on an
+experiment aimed at measuring small optical directional anisotropies by
+frequency metrology in a high finesse ring cavity. We focus on our first
+experimental goal, the measurement of magneto-electric effects in gases. After
+a review of the expected effects in our set-up, we present the apparatus and
+the measurement procedure, showing that we already have the necessary
+sensitivity to start novel experiments.",1101.1174v1
+2011-01-11,Deconfined criticality for the S=1 spin model on the spatially anisotropic triangular lattice,"The quantum S=1 spin model on the spatially anisotropic triangular lattice is
+investigated numerically. The nematic and valence-bond-solid (VBS) phases are
+realized by adjusting the spatial anisotropy and the biquadratic interaction.
+The phase transition between the nematic and VBS phases is expected to be a
+continuous one with unconventional critical indices (deconfined criticality).
+The geometrical character (spatial anisotropy) is taken into account by
+imposing the screw-boundary condition (Novotny's method). Diagonalizing the
+finite-size cluster with N \le 20 spins, we observe a clear indication of
+continuous phase transition. The correlation-length critical exponent is
+estimated as \nu=0.92(10).",1101.1999v1
+2011-01-13,The three dimensional Heisenberg spin glass under a weak random anisotropy,"We perform a finite size scaling study of the three-dimensional Heisenberg
+spin glass in the presence of weak random anisotropic interactions, up to sizes
+L=32. Anisotropies have a major impact on the phase transition. The
+chiral-glass susceptibility does not diverge, due to a large anomalous
+dimension. It follows that the anisotropic spin-glass belongs to a Universality
+Class different from the isotropic model, which questions the applicability of
+the chirality scenario.",1101.2509v2
+2011-02-14,Interaction of spin and vibrations in transport through single-molecule magnets,"We study linear electron transport through a single-molecule magnet (SMM) and
+the interplay of its anisotropic spin with quantized vibrational distortions of
+the molecule. We show that, despite the longitudinal anisotropy barrier and
+small transverse anisotropy, vibrational fluctuations can induce quantum
+spin-tunneling (QST) and a QST-Kondo effect. The interplay of spin scattering,
+QST and molecular vibrations can strongly enhance the Kondo effect and induce
+an anomalous magnetic field dependence of vibrational Kondo side-bands.",1102.2798v1
+2011-02-15,Adaptation to anisotropy and inhomogeneity via dyadic piecewise polynomial selection,"This article is devoted to nonlinear approximation and estimation via
+piecewise polynomials built on partitions into dyadic rectangles. The
+approximation rate is studied over possibly inhomogeneous and anisotropic
+smoothness classes that contain Besov classes. Highlighting the interest of
+such a result in statistics, adaptation in the minimax sense to both
+inhomogeneity and anisotropy of a related multivariate density estimator is
+proved. Besides, that estimation procedure can be implemented with a
+computational complexity simply linear in the sample size.",1102.3108v1
+2011-02-24,Anisotropy studies with multiscale autocorrelation function,"We present a novel method, based on a multiscale approach, for detecting
+anisotropy signatures in the arrival direction distribution of the highest
+energy cosmic rays. This method is catalog independent, i.e. it does not depend
+on the choice of a particular catalog of candidate sources, and it provides a
+good discrimination power even in presence of contaminating isotropic
+background. We present applications to simulated data sets of events
+corresponding to plausible scenarios for events detected, in the last decades,
+by world-wide surface detector-based observatories for charged particles.",1102.5007v1
+2011-03-06,Spin-wave energy dispersion of a frustrated spin-1/2 Heisenberg antiferromagnet on a stacked square lattice,"Effects of interlayer coupling and spatial anisotropy on spin-wave excitation
+spectra of a three-dimensional spatially anisotropic, frustrated spin-$\half$
+Heisenberg antiferromagnet (HAFM) is investigated for the two ordered phases
+using second-order spin-wave expansion. We show that the second-order
+corrections to the spin-wave energies are significant and find that the energy
+spectra of the three-dimensional HAFM shares similar qualitative features with
+the energy spectra of the two-dimensional HAFM on a square lattice. We also
+discuss the features that can provide experimental measures for the strength of
+the interlayer coupling, spatial anisotropy parameter, and magnetic
+frustration.",1103.1155v1
+2011-03-08,Quantum Phase Transitions around the Staggered Valence Bond Solid,"Motivated by recent numerical results, we study the quantum phase transitions
+between Z_2 spin liquid, Neel ordered, and various valence bond solid (VBS)
+states on the honeycomb and square lattices, with emphasis on the staggered
+VBS. In contrast to the well-understood columnar VBS order, the staggered VBS
+is not described by an XY order parameter with Z_N anisotropy close to these
+quantum phase transitions. Instead, we demonstrate that on the honeycomb
+lattice, the staggered VBS is more appropriately described as an O(3) or CP(2)
+order parameter with cubic anisotropy, while on the square lattice it is
+described by an O(4) or CP(3) order parameter.",1103.1638v1
+2011-03-15,Ellipsoidal anisotropy in elasticity for rocks and rock masses,"One of the interesting features with the ellipsoidal models of anisotropy
+presented in this paper is their acceptance of analytical solutions for some of
+the basic elasticity problems. It was shown by Pouya (2000) and Pouya and Zaoui
+(2006) that many closed-form solutions for basic problems involving linear
+isotropic materials could be extended by linear transformation to cover a
+variety of ""ellipsoidal"" materials. This paper will describe two main varieties
+of ellipsoidal elastic models and show how well they fit the in situ data for
+sedimentary rocks; numerical homogenization results for several varieties of
+fractured rock masses will also be provided.",1103.3033v1
+2011-04-12,Upper critical fields and superconducting anisotropy of K0.70Fe1.55Se1.01S0.99 and K0.76Fe1.61Se0.96S1.04 single crystals,"We have investigated temperature and angular dependence of resistivity of
+K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2) and K0.76(5)Fe1.61(5)Se0.96(4)S1.04(5)
+single crystals. The upper critical fields Hc2(T) for both field directions
+decrease with the increase in S content. On the other hand, the angle-dependent
+magnetoresistivity for both compounds can be scaled onto one curve using the
+anisotropic Ginzburg-Landau theory. The obtained anisotropy of Hc2(T) increases
+with S content, implying that S doping might decrease the dimensionality of
+certain Fermi surface parts, leading to stronger two dimensional character.",1104.2318v2
+2011-04-14,The Cosmic Linear Anisotropy Solving System (CLASS) I: Overview,"The Cosmic Linear Anisotropy Solving System (CLASS) is a new accurate
+Boltzmann code, designed to offer a more user-friendly and flexible coding
+environment to cosmologists. CLASS is very structured, easy to modify, and
+offers a rigorous way to control the accuracy of output quantities. It is also
+incidentally a bit faster than other codes. In this overview, we present the
+general principles of CLASS and its basic structure. We insist on the
+friendliness and flexibility aspects, while accuracy, physical approximations
+and performances are discussed in a series of companion papers.",1104.2932v2
+2011-04-28,Temperature dependent anisotropy and elastic effects in ferromagnetic nanowire arrays,"Temperature dependent Ferromagnetic Resonance measurements performed as a
+function of diameter on Nickel nanowire arrays reveal several interesting
+features in these systems. With diameter decrease from 100 nm to 15 nm, a
+transition induced by surface anisotropy increase is observed at 50 nm in easy
+axis orientation from parallel to perpendicular with respect to individual
+nanowire geometric axis. Analysis of resonance field $H_{res}$ temperature
+variation (between liquid Helium and room temperature) reveals underlying
+strong magneto-elastic effects in small and large diameter nanowire arrays with
+potential applications in recording and spintronics.",1104.5348v3
+2011-06-21,Josephson effect through an anisotropic magnetic molecule,"We study the Josephson effect through a magnetic molecule with anisotropic
+properties. Performing calculations in the tunneling regime, we show that the
+exchange coupling between the electron spin on the molecule and the molecular
+spin can trigger a transition from the $\pi$ state to the 0 state, and we study
+how the spin anisotropy affects this transition. We show that the behavior of
+the critical current as a function of an external magnetic field can give
+access to valuable information about the spin anisotropy of the molecule.",1106.4193v2
+2011-06-22,Magnetic anisotropy at nanoscale,"Nanoscale objects often behave differently than their 'normal-sized'
+counterparts. Sometimes it is enough to be small in just one direction to
+exhibit unusual features. One example of such a phenomenon is a very specific
+in-plane magnetic anisotropy observed sometimes in very thin layers of various
+materials. Here we recall a peculiar form of the free energy functional nicely
+describing the experimental findings but completely irrelevant and thus never
+observed in larger objects.",1106.4515v1
+2011-07-13,Multichannel Effects near Confinement-Induced Resonances in Harmonic Waveguides,"We analyze the impact of multichannel scattering in harmonic waveguides on
+the positions and widths of confinement-induced resonances for both isotropic
+and anisotropic transversal confinement. Multichannel scattering amplitudes and
+transmission coefficients are calculated and used to characterize the resonant
+behaviour of atomic collisions with varying anisotropy. A mechanism is
+established which leads to a splitting of the confinement-induced resonance in
+the presence of anisotropy.",1107.2501v2
+2011-08-12,Universal amplitude ratios for scaling corrections on Ising strips with fixed boundary conditions,"We study the (analytic) finite-size corrections in the Ising model on the
+strip with fixed ($+ -$) boundary conditions. We find that subdominant
+finite-size corrections to scaling should be to the form $a_k/N^{2k-1}$ for the
+free energy $f_N$ and $b_k^{(n)}/N^{2k-1}$ for inverse correlation length
+$\xi_n^{-1}$, with integer value of $k$. We investigate the set $\{a_k,
+b_k^{(n)}\}$ by exact evaluation and their changes upon varying anisotropy of
+coupling. We find that the amplitude ratios $b_k^{(n)}/a_k$ remain constant
+upon varying coupling anisotropy. Such universal behavior are correctly
+reproduced by the conformal perturbative approach.",1108.2574v1
+2011-08-31,Extensibility enables locomotion under isotropic drag,"Anisotropic viscous drag is usually believed to be a requirement for the low
+Reynolds number locomotion of slender bodies such as flagella and cilia. Here
+we show that locomotion under isotropic drag is possible for extensible slender
+bodies. After general considerations, a two-ring swimmer and a model
+dinoflagellate flagellum are studied analytically to illustrate how
+extensibility can be exploited for self-propulsion without drag anisotropy.
+This new degree of freedom could be useful for some complex swimmer geometries
+and locomotion in complex fluid environments where drag anisotropy is weak or
+even absent.",1109.0047v1
+2011-09-03,Thermomagnetic instability of standing flux-antiflux front in layered type-II superconductors,"Stability of standing flux-antiflux front in anisotropic layered
+superconductors is considered. We describe two assisting mechanisms
+destabilizing the standing vortex-antivortex front. There are anisotropy of the
+layered superconductors and the heat, released by the vortex dynamics. We
+present the conditions of the front stability for various anisotropy and
+heating parameters. We predict that even small vortex-antivortex heating can
+result in front instability. The characteristic size of the unstable pattern is
+estimated.",1109.0637v1
+2011-09-09,Theoretical Investigation of the Magnetic Order in FeAs,"The magnetic structure of the iron monoarsenide FeAs is studied using
+first-principles calculations. We consider the collinear and non-collinear
+(spin-spiral wave) magnetic ordering and magnetic anisotropy. It is
+analitically shown that a magnetic triaxial anisotropy results in a sum of two
+spin-spiral waves with opposite directions of wave vectors and different spin
+amplitudes, so that the magnetic moments in two perpendicular directions do not
+equal each other.",1109.1924v1
+2011-09-09,Non-Gaussianity in the Cosmic Microwave Background Anisotropies at Recombination in the Squeezed limit,"We estimate analytically the second-order cosmic microwave background
+temperature anisotropies at the recombination epoch in the squeezed limit and
+we deduce the contamination to the primordial local non-Gaussianity. We find
+that the level of contamination corresponds to f_NL^{con}=O(1) which is below
+the sensitivity of present experiments and smaller than the value O(5) recently
+claimed in the literature.",1109.2043v2
+2011-11-07,"Spatially fractional-order viscoelasticity, non-locality and a new kind of anisotropy","Spatial non-locality of space-fractional viscoelastic equations of motion is
+studied. Relaxation effects are accounted for by replacing second-order time
+derivatives by lower-order fractional derivatives and their generalizations. It
+is shown that space-fractional equations of motion of an order strictly less
+than 2 allow for a new kind anisotropy, associated with angular dependence of
+non-local interactions between stress and strain at different material points.
+Constitutive equations of such viscoelastic media are determined. Explicit
+fundamental solutions of the Cauchy problem are constructed for some cases
+isotropic and anisotropic non-locality.",1111.1680v1
+2011-11-22,Role of anisotropy in the Förster energy transfer from a semiconductor quantum well to an organic crystalline overlayer,"We consider the non-radiative resonant energy transfer from a two-dimensional
+Wannier exciton (donor) to a Frenkel exciton of a molecular crystal overlayer
+(acceptor). We characterize the effect of the optical anisotropy of the organic
+subsystem on this process. Using realistic values of material parameters, we
+show that it is possible to change the transfer rate within typically a factor
+of two depending on the orientation of the crystalline overlayer. The resonant
+matching of donor and acceptor energies is also partly tunable via the organic
+crystal orientation.",1111.5154v1
+2011-11-22,Basic Properties of MHD Turbulence in the Inertial Range,"We revisit the issue of spectral slope of MHD turbulence in the inertial
+range and argue that numerics favor Goldreich-Sridhar -5/3 slope rather than
+-3/2 slope. We also did precision measurements of anisotropy of MHD turbulence
+and determined the anisotropy constant C_A=0.34 of Alfvenic turbulence.
+Together with previously measured Kolmogorov constant C_K=4.2, or 3.3 for
+purely Alfvenic case, it constitutes a full description of MHD cascade in terms
+of spectral quantities, which is of high practical value for astrophysics.",1111.5329v2
+2011-11-26,Orientation selection of equiaxed dendritic growth by three-dimensional cellular automaton model,"A three-dimensional (3-D) adaptive mesh refinement (AMR) cellular automata
+(CA) model is developed to simulate the equiaxed dendritic growth of pure
+substance. In order to reduce the mesh induced anisotropy by CA capture rules,
+a limited neighbor solid fraction (LNSF) method is presented. An expansion
+description using two interface free energy anisotropy parameters (\epsilon1,
+\epsilon2) is used in present 3-D CA model. The dendrite growths with the
+orientation selection between <100> and <110> are discussed using the different
+\epsilon1 with \epsilon2=-0.02. It is found that the simulated morphologies by
+present CA model are as expected from the minimum stiffness criterion.",1111.6159v1
+2011-12-16,Competition between superconductivity and nematic order : anisotropy of superconducting coherence length,"We study the interplay between nematic order and superconductivity, motivated
+by a recent experiment on FeSe observing strongly distorted vortex shapes (Song
+et al., Science 332, 1410 (2011)). We show that the nematic order strongly
+enhances the anisotropy in the superconducting coherence length, beyond that
+expected from considerations of the Ginzburg-Landau theory. We obtain universal
+functions describing the coupling between the nematic order and
+superconductivity, and discuss connections of our results to the experiments.",1112.3973v2
+2012-01-17,Spin wave excitation in magnetic insulators by spin-transfer torque,"We study the excitation of spin waves in magnetic insulators by the
+current-induced spin-transfer torque. We predict preferential excitation of
+surface spin waves induced by an easy-axis surface anisotropy with critical
+current inversely proportional to the penetration depth and surface anisotropy.
+The surface modes strongly reduce the critical current and enhance the
+excitation power of the current-induced magnetization dynamics.",1201.3442v1
+2012-01-23,Local lattice distortions around $\rm{Mn^{2+}}$ cause in-plane uniaxial magnetic anisotropy in Ga(Mn)As,"We theoretically investigate the interplay between local lattice distortions
+around $\rm{Mn^{2+}}$ ion impurity and the ion's magnetic polarization,
+mediated through spin-orbit coupling of hole. We show that the tetrahedral
+symmetry around $\rm{Mn^{2+}}$ ion impurity is spontaneously broken even in the
+paramagnetic regime. Modest local lattice distortions around the impurity
+$\rm{Mn^{2+}}$ ion, along with the growth strain, stabilize magnetization along
+$< 110 >$ directions, in the ferromagnetic regime. We explain the
+experimentally observed in-plane uniaxial magnetic anisotropy seen in this
+system using this symmetry-breaking mechanism.",1201.4879v2
+2012-01-26,Thermal switching rate of a ferromagnetic material with uniaxial anisotropy,"The field dependence of the thermal switching rate of a ferromagnetic
+material with uniaxial anisotropy was studied by solving the Fokker-Planck
+equation. We derived the analytical expression of the thermal switching rate
+using the mean first-passage time approach, and found that Brown's formula
+[Phys. Rev. 130, 1677 (1963)] is applicable even in the low barrier limit by
+replacing the attempt frequency with the proper factor which is expressed by
+the error function.",1201.5460v2
+2012-01-26,Ground-state correlation properties of charged bosons trapped in strongly anisotropic harmonic potentials,"We study systems of a few charged bosons contained within a strongly
+anisotropic harmonic trap. A detailed examination of the ground-state
+correlation properties of two-, three-, and four-particle systems is carried
+out within the framework of the single-mode approximation of the transverse
+components. The linear correlation entropy of the quasi-1D systems is discussed
+in dependence on the confinement anisotropy and compared with a strictly 1D
+limit. Only at weak interaction the correlation properties depend strongly on
+the anisotropy parameter.",1201.5504v1
+2012-01-31,Statistical Anisotropy from Anisotropic Inflation,"We review an inflationary scenario with the anisotropic expansion rate. An
+anisotropic inflationary universe can be realized by a vector field coupled
+with an inflaton, which can be regarded as a counter example to the cosmic
+no-hair conjecture. We show generality of anisotropic inflation and derive a
+universal property. We formulate cosmological perturbation theory in
+anisotropic inflation. Using the formalism, we show anisotropic inflation gives
+rise to the statistical anisotropy in primordial fluctuations. We also explain
+a method to test anisotropic inflation using the cosmic microwave background
+radiation (CMB).",1201.6434v2
+2012-02-15,Measurement of Cosmic Ray spectrum and Anisotropy with ARGO-YBJ,"In this paper we report on the observation of the anisotropy of cosmic ray
+arrival direction at different angular scales with ARGO-YBJ. Evidence of new
+few-degree excesses throughout the sky region 195$^{\circ}\leq$ R.A. $\leq$
+315$^{\circ}$ is presented for the first time. We report also on the
+measurement of the light-component (p+He) spectrum of primary cosmic rays in
+the range 5 - 200 TeV.",1202.3379v1
+2012-02-21,High-Directional Wave Propagation in Periodic Gain/Loss Modulated Materials,"Amplification/attenuation of light waves in artificial materials with a
+gain/loss modulation on the wavelength scale can be sensitive to the
+propagation direction. We give a numerical proof of the high anisotropy of the
+gain/loss in two dimensional periodic structures with square and rhombic
+lattice symmetry by solving the full set of Maxwell's equations using the
+finite difference time domain method. Anisotropy of amplification/attenuation
+leads to the narrowing of the angular spectrum of propagating radiation with
+wavevectors close to the edges of the first Brillouin Zone. The effect provides
+a novel and useful method to filter out high spatial harmonics from noisy
+beams.",1202.4585v1
+2012-02-23,Domain structure in CoFeB thin films with perpendicular magnetic anisotropy,"Domain structures in CoFeB-MgO thin films with a perpendicular easy
+magnetization axis were observed by magneto-optic Kerr-effect microscopy at
+various temperatures. The domain wall surface energy was obtained by analyzing
+the spatial period of the stripe domains and fitting established domain models
+to the period. In combination with SQUID measurements of magnetization and
+anisotropy energy, this leads to an estimate of the exchange stiffness and
+domain wall width in these films. These parameters are essential for
+determining whether domain walls will form in patterned structures and devices
+made of such materials.",1202.5128v1
+2012-04-04,CMBR anisotropy in the framework of cosmological extrapolation of MOND,"A modified gravity involving a critical acceleration, as empirically
+established at galactic scales and successfully tested by data on supernovae of
+type Ia, can fit the measured multipole spectrum of anisotropy in the cosmic
+microwave background radiation, so that a dark sector of Universe is
+constructively mimicked as caused by the dynamics beyond the general
+relativity. Physical consequences, verifiable predictions and falsifiable
+issues are listed and discussed.",1204.0869v2
+2012-04-30,Statistically anisotropic curvature perturbation generated during the waterfall,"If the waterfall field of hybrid inflation couples to a U(1) gauge field, the
+waterfall can generate a statistically anisotropic contribution to the
+curvature perturbation. We investigate this possibility, generalising in
+several directions the seminal work of Yokoyama and Soda. The statistical
+anisotropy of the bispectrum could be detectable by PLANCK even if the
+statistical anisotropy of the spectrum is too small to detect.",1204.6619v1
+2012-05-25,Higher order spectra from an initially anisotropic universe,"In this paper, we present the higher order spectra of a scalar field produced
+through the higher derivative interactions in the initially anisotropic
+universe. Although we ignore the backreaction of the scalar field on the
+geometry, our analysis should have much overlap with the quantum fluctuations
+of the inflaton field in the anisotropic universe. We also include the planar
+modes whose momenta are along the plane which is perpendicular to the
+primordial preferred direction, for which effects of the initial anisotropy are
+not suppressed. The presence of a negative frequency mode produces features
+distinguishable from the case of the de Sitter inflation. We also show that
+richer features appear in the trispectra due to the primordial anisotropy.",1205.5600v1
+2012-05-27,Superfluid state of repulsively interacting three-component fermionic atoms in optical lattices,"We investigate the superfluid state of repulsively interacting
+three-component (color) fermionic atoms in optical lattices. When the
+anisotropy of the three repulsive interactions is strong, atoms of two of the
+three colors form Cooper pairs and atoms of the third color remain a Fermi
+liquid. An effective attractive interaction is induced by density fluctuations
+of the third-color atoms. This superfluid state is stable against changes in
+filling close to half filling. We determine the phase diagrams in terms of
+temperature, filling, and the anisotropy of the repulsive interactions.",1205.5964v1
+2012-05-29,Anisotropic excitation spectrum of a dipolar quantum Bose gas,"We measure the excitation spectrum of a dipolar Chromium Bose Einstein
+Condensate with Raman-Bragg spectroscopy. The energy spectrum depends on the
+orientation of the dipoles with respect to the excitation momentum,
+demonstrating an anisotropy which originates from the dipole-dipole
+interactions between the atoms. We compare our results with the Bogoliubov
+theory based on the local density approximation, and, at large excitation
+wavelengths, with numerical simulations of the time dependent Gross-Pitaevskii
+equation. Our results show an anisotropy of the speed of sound",1205.6305v1
+2012-06-13,Anisotropic Friedmann-Robertson-Walker universe from nonlinear massive gravity,"In the scope of the nonlinear massive gravity, we study fixed points of
+evolution equations for a Bianchi type--I universe. We find a new attractor
+solution with non-vanishing anisotropy, on which the physical metric is
+isotropic but the Stuckelberg configuration is anisotropic. As a result, at the
+background level, the solution describes a homogeneous and isotropic universe,
+while a statistical anisotropy is expected from perturbations, suppressed by
+smallness of the graviton mass.",1206.2723v2
+2012-06-23,Interacting Anisotropic Dirac Fermions in Strained Graphene and Related Systems,"We study the role of long-range electron-electron interactions in a system of
+two-dimensional anisotropic Dirac fermions, which naturally appear in
+uniaxially strained graphene, graphene in external potentials, some strongly
+anisotropic topological insulators, and engineered anisotropic graphene
+structures. We find that while for small interactions and anisotropy the system
+restores the conventional isotropic Dirac liquid behavior, strong enough
+anisotropy can lead to the formation of a quasi-one dimensional electronic
+phase with dominant charge order (anisotropic excitonic insulator).",1206.5427v2
+2012-06-27,Domain wall propagation through spin wave emission,"We theoretically study field-induced domain wall (DW) motion in an
+electrically insulating ferromagnet with hard- and easy-axis anisotropies. DWs
+can propagate along a dissipationless wire through spin wave emission locked
+into the known soliton velocity at low fields. In the presence of damping, the
+mode appears before the Walker breakdown field for strong out-of-plane magnetic
+anisotropy, and the usual Walker rigid-body propagation mode becomes unstable
+when the field is between the maximal-DW-speed field and Walker breakdown
+field.",1206.6244v1
+2012-07-27,A Theory for Diffusionless Structural Phase Transitions in BaTiO3 and PZT Single Crystals,"A phenomenological theory has been proposed for the diffusionless structural
+phase transitions in crystalline solids here. It has been found that for BaTiO3
+single crystal, both the phase transitions and the crystal structures can be
+predicted with the crystalline anisotropy constants and order parameter
+dependent strain constants that depend on the temperature. The results have
+also shown that the morphotropic phase boundaries in PZT crystals arise from
+the crystalline anisotropy.",1207.6532v2
+2012-08-03,Quantum measurements and chiral magnetic effect,"The effect of anisotropy for fluctuations of electric currents in magnetic
+field is addressed within framework of quantum measurements theory. It is shown
+that for free fermions in uniform magnetic field the anisotropy is of the same
+sign as one expects for chiral magnetic effect and is related to triangle
+anomaly. The corresponding decoherence functional contains anomalous
+off-diagonal terms leading to correlation of fluctuations between observables
+of opposite P-parity.",1208.0777v2
+2012-08-13,Highly anisotropic dissipative hydrodynamics,"The quark gluon plasma generated in ultrarelativistic heavy ion collisions
+may possess sizable momentum-space anisotropies that cause the longitudinal and
+transverse pressures in the local rest frame to be significantly different. We
+review recent attempts to derive a dynamical framework that can reliably
+describe systems that possess a high degree of momentum-space anisotropy. The
+dynamical framework that has been developed can describe the evolution of the
+quark gluon plasma ranging from the longitudinal free-streaming limit to the
+ideal hydrodynamical limit.",1208.2626v2
+2012-09-24,Control of the magnetism and magnetic anisotropy of a single-molecule magnet with an electric field,"Through systematics density functional calculations, the mechanism of the
+substrate induced spin reorientation transition in FePc/O-Cu(110) was explained
+in terms of charge transfer and rearrangement of Fe-d orbitals. Moreover, we
+found giant magnetoelectric effects in this system, manifested by the sensitive
+dependences of its magnetic moment and magnetic anisotropy energy on external
+electric field. In particular, the direction of magnetization of FePc/O-Cu(110)
+is switchable between in-plane and perpendicular axes, simply by applying an
+external electric field of 0.5 eV/{\AA} along the surface normal.",1209.5453v3
+2012-10-05,Anisotropic Fermi Contour of (001) GaAs Holes in Parallel Magnetic Fields,"We report a severe, spin-dependent, Fermi contour anisotropy induced by
+parallel magnetic field in a high-mobility (001) GaAs two-dimensional hole
+system. Employing commensurability oscillations created by a unidirectional,
+surface-strain-induced, periodic potential modulation, we directly probe the
+anisotropy of the two spin subband Fermi contours. Their areas are obtained
+from the Fourier transform of the Shubnikov-de Haas oscillations. Our findings
+are in semi-quantitative agreement with the results of parameter-free
+calculations of the energy bands.",1210.1672v1
+2012-10-17,Topological transition of Dirac points in a microwave experiment,"By means of a microwave tight-binding analogue experiment of a graphene-like
+lattice, we observe a topological transition between a phase with a point-like
+band gap characteristic of massless Dirac fermions and a gapped phase. By
+applying a controlled anisotropy on the structure, we investigate the
+transition directly via density of states measurements. The wave function
+associated with each eigenvalue is mapped and reveals new states at the Dirac
+point, localized on the armchair edges. We find that with increasing
+anisotropy, these new states are more and more localized at the edges.",1210.4642v2
+2012-10-27,Nonlinear optical anisotropy due to freed electrons,"We present a computational study of the pump-probe response of a single atom
+to assess any microscopic nonlinear optical anisotropy due to freed electrons
+for non-resonant optical excitation. Using simulations of the Schr\""odinger
+equation for an atom exposed to a strong, short-duration linearly polarized
+pump, we calculate the induced dipole moment along probe directions parallel
+and perpendicular to the pump polarization. Our simulations show birefringence
+ratios of approximately 0.78-0.9 on the timescale of tens of femtoseconds
+following the excitation pulse.",1210.7285v1
+2012-11-06,Spin Wave Scattering in Ferromagnetic Cross,"Spin wave scattering in the right angle ferromagnetic cross was measured.
+Shape anisotropy defined magnetization ground states at zero biasing magnetic
+fields. Scattering of the spin waves in the center of ferromagnetic cross is
+strongly dependent on the amplitude and angle of the biasing magnetic field.
+Micromagnetic simulations indicate that low in-plane biasing magnetic fields
+rotate the magnetization of the cross center while the arms stay axially
+magnetized due to the shape anisotropy. We discuss effect of biasing magnetic
+fields on the spin wave scattering and approaches to an effective spin wave
+switch based on the fabricated structure.",1211.1259v1
+2012-11-20,Novel Two-dimensional Carbon Allotrope with Strong Electronic Anisotropy,"Two novel two-dimensional carbon allotropes comprised of octagons and
+pentagons are proposed based on the first-principles calculations. The two
+carbon allotropes, named OPG-L and OPG-Z, are found to have distinct
+properties. OPG-L is metallic, while OPG-Z is a gapless semimetal. Remarkably,
+OPG-Z exhibits pronounced electronic anisotropy with highly anisotropic Dirac
+points at the Fermi level. A tight-binding model is suggested to describe the
+low-energy quasiparticles, which clarifies the origin of the anisotropic Dirac
+points. Such an anisotropic electronic characteristic of OPG-Z is expected to
+have wide implications in nano-electronics.",1211.4680v2
+2012-11-30,Ab initio study of magnetic anisotropy in cobalt doped zinc oxide with electron-filling,"Based on first-principles calculation, it has been predicted that the
+magnetic anisotropy energy (MAE) in Co-doped ZnO (Co:ZnO) depends on
+electron-filling. Results show that the charge neutral Co:ZnO presents a ""easy
+plane"" magnetic state. While modifying the total number of electrons, the easy
+axis rotates from in-plane to out-of-plane. The alternation of the MAE is
+considered to be the change of the ground state of Co ion, resulting from the
+relocating of electrons on Co d-orbitals with electron-filling.",1211.7287v2
+2012-12-13,Measurement of J/{psi} Azimuthal Anisotropy in Au+Au Collisions at {sqrt{s_{NN}}} = 200 GeV,"The measurement of J/{psi} azimuthal anisotropy is presented as a function of
+transverse momentum for different centralities in Au+Au collisions at
+{sqrt{s_{NN}}} = 200 GeV. The measured J/{psi} elliptic flow is consistent with
+zero within errors for transverse momentum between 2 and 10 GeV/c. Our
+measurement suggests that J/{psi} with relatively large transverse momentum are
+not dominantly produced by coalescence from thermalized charm quarks, when
+comparing to model calculations.",1212.3304v2
+2012-12-15,Event plane resolution correction for azimuthal anisotropy in wide centrality bins,"We provide a method to correct the observed azimuthal anisotropy in heavy-ion
+collisions for the event plane resolution in a wide centrality bin. This new
+procedure is especially useful for rare particles, such as Omega baryons and
+J/psi mesons, which are difficult to measure in small intervals of centrality.
+Based on a Monte Carlo calculation with simulated v_2 and multiplicity, we show
+that some of the commonly used methods have a bias of up to 15%.",1212.3650v2
+2013-01-17,Electric-field control of domain wall nucleation and pinning in a metallic ferromagnet,"The electric (E) field control of magnetic properties opens the prospects of
+an alternative to magnetic field or electric current activation to control
+magnetization. Multilayers with perpendicular magnetic anisotropy (PMA) have
+proven to be particularly sensitive to the influence of an E-field due to the
+interfacial origin of their anisotropy. In these systems, E-field effects have
+been recently applied to assist magnetization switching and control domain wall
+(DW) velocity. Here we report on two new applications of the E-field in a
+similar material : controlling DW nucleation and stopping DW propagation at the
+edge of the electrode.",1301.4007v1
+2013-01-24,Pressure effects in hollow and solid iron oxide nanoparticles,"We report a study on the pressure response of the anisotropy energy of hollow
+and solid maghemite nanoparticles. The differences between the maghemite
+samples are understood in terms of size, magnetic anisotropy and shape of the
+particles. In particular, the differences between hollow and solid samples are
+due to the different shape of the nanoparticles and by comparing both pressure
+responses it is possible to conclude that the shell has a larger pressure
+response when compared to the core.",1301.5708v1
+2013-01-29,Continuum random sequential adsorption of polymer on a flat and homogeneous surface,"Random sequential adsorption (RSA) of polymer, modeled as a chain of
+identical spheres, is systematically studied. In order to control precisely
+anisotropy and number of degrees of freedom, two different kinds of polymers
+are used. In the first one, monomers are placed along a straight line, whereas
+in the second, relative orientations of particles are random. Such polymers
+fill a flat homogeneous surface randomly. The paper focuses on maximal random
+coverage ratio and adsorption kinetics dependence on polymer size, shape
+anisotropy, and numbers of degrees of freedom. Obtained results were discussed
+and compared with other numerical experiments and theoretical predictions.",1301.6964v2
+2013-02-07,CMB Tensor Anisotropies in f(R) Gravity,"The cosmic microwave background (CMB) carries information from the last
+scattering surface that puts constraints on the multitude of proposed
+cosmological models and the gravitation theories they are based on. One class
+of such theories is $f(R)$ gravity, which has become an interesting endeavour
+to correct for the degeneracies of the concordance model.
+  We presents a description of CMB anisotropies generated by tensor
+perturbations in $f(R)$ theories of gravity. The temperature and the $E$-mode
+polarisation power spectra in the special case of $f(R)=R^n$ are computed using
+a modified version of CAMB package.",1302.1887v1
+2013-02-09,Existence and uniqueness for planar anisotropic and crystalline curvature flow,"We prove short-time existence of \phi-regular solutions to the planar
+anisotropic curvature flow, including the crystalline case, with an additional
+forcing term possibly unbounded and discontinuous in time, such as for instance
+a white noise. We also prove uniqueness of such solutions when the anisotropy
+is smooth and elliptic. The main tools are the use of an implicit variational
+scheme in order to define the evolution, and the approximation with flows
+corresponding to regular anisotropies.",1302.2216v1
+2013-02-28,Polarization dependences of terahertz radiation emitted by hot charge carriers in p-Te,"Polarization dependences of the terahertz radiation emitted by hot charge
+carriers in p-Te have been studied both theoretically and experimentally. The
+angular dependences of the spontaneous radiation emission by hot carriers is
+shown to originate from the anisotropy of their dispersion law and the
+anisotropy of the dielectric permittivity of a tellurium crystal. We have shown
+that the polarization dependences of radiation are determined by the angle
+between the crystallographic axis C3 in p-Te and the polarization vector; they
+are found to have a periodic character.",1302.7182v1
+2013-03-08,Central compact objects in magnetic lethargy,"Central Compact Objects are peculiar young neutron stars, with very low
+external magnetic fields combined with high fluxes in the X-ray band and
+surface temperature anisotropies. However, in their crust the magnetic field
+can be strong, result of its burial during a short post-supernova hypercritical
+accretion episode. The implications of this latter scenario for the temperature
+anisotropy, pulsed fraction and luminosity are discussed.",1303.1997v1
+2013-04-04,Spin-orbit coupling induced Fulde-Ferrell-Larkin-Ovchinnikov-like Cooper pairing and skyrmion-like polarization textures in trapped optical lattices,"We study the interplay between the Zeeman field and spin-orbit coupling (SOC)
+in harmonically trapped Fermi gases loaded into a two-dimensional single-band
+tight-binding optical lattice. Using the Bogoliubov-de Gennes theory, we find
+that the Zeeman field combined with a Rashba SOC gives rise to $(i)$
+Fulde-Ferrell-like superfluidity and $(ii)$ skyrmion-like polarization textures
+near the edges of the system. We also discussed the effects of interaction,
+temperature, SOC anisotropy and Zeeman field anisotropy on the superfluid
+ground state and polarization textures.",1304.1473v2
+2013-04-10,Effect of anisotropic Fermi surface on the flux-flow resistivity under rotating magnetic field,"We numerically investigate the effect of in-plane anisotropic Fermi surface
+(FS) on the flux-flow resistivity $\rho_{\rm f}$ under rotating magnetic field
+on the basis of the quasiclassical Green's function method. We demonstrate that
+one can detect the phase in pairing potential of Cooper pair through the
+field-angular dependence of $\rho_{\rm f}$ even if the FS has in-plane
+anisotropy. In addition, we point out one can detect the gap-node directions
+irrespective of the FS anisotropy by measuring $\rho_{\rm f}$ under rotating
+field.",1304.3164v1
+2013-04-19,Spin nematic states in spin-1 antiferromagnets with easy-axis anisotropy,"It is well known that spin nematic phases can appear in either frustrated
+magnets or in those described by Hamiltonians with large exotic non-Heisenberg
+terms like biquadratic exchange. We show in the present study that
+non-frustrated spin-1 1D, 2D and 3D antiferromagnets with single-ion easy-axis
+anisotropy can show nematic phases in strong magnetic field. For 1D case we
+support our analytical results by numerical ones.",1304.5467v1
+2013-05-01,Azimuthal Anisotropy in U+U Collisions at $\sqrt{s_{NN}} = 193 $ GeV with STAR Detector at RHIC,"We report the measurement of first (\textit {n} = 1) and higher
+order(\textit{n} = 2-5) harmonic coefficients ($v_{n}$) of the azimuthal
+anisotropy in the distribution of the particles produced in U+U collisions at
+$\sqrt{s_{NN}}$ =193 GeV, recorded with the STAR detector at RHIC. The
+differential measurement of $(v_{n})$ is presented as a function of transverse
+momentum ($p_{T}$) and centrality. We also present $v_{n}$ measurement in the
+ultra-central collisions. These data may provide strong constraints on the
+theoretical models of the initial condition in heavy ion collisions and the
+transport properties of the produced medium.",1305.0173v1
+2013-05-06,Anisotropy of Interfacial Energy in Five Dimensions,"Anisotropy of interfacial energy is the principal driving force for material
+microstructure evolution yet its origins remain uncertain and a quantitative
+description lacking. We present and justify a concise hypothesis on the
+topography and topology of the functional space of grain boundary energies and,
+based on this hypothesis, construct a closed-form function that quantitatively
+describes energy variations in the entire 5-space of macroscopic parameters
+defining grain boundary geometry. The new function is found to be universal for
+the crystallography class of face-centered cubic metals.",1305.1282v1
+2013-05-07,Spin Wave Excitation in Magnetic Insulator Thin Films by Spin-Transfer Torque,"We describe excitation of dipole-exchange spin waves in insulating magnetic
+thin films by spin current injection at the surface of the film. An easy-axis
+magnetic surface anisotropy can induce a non-chiral surface spin wave mode with
+penetration depth inversely proportional to the strength of the surface
+anisotropy, which strongly reduces the critical current and enhances the
+excitation power. The importance of the interface spin wave modes on the
+excitation spectrum is reduced by spin pumping, which depends on the quality of
+the interface as expressed by the spin mixing conductance.",1305.1364v2
+2013-06-27,Speed of sound of a Bose--Einstein condensate with dipole--dipole interactions,"In the present work the case of a chromium Bose-Einstein condensate is
+considered. The model includes not only the presence of the so-called contact
+interaction but also a long range and anisotropic dipole-dipole interaction has
+been included. Some thermodynamical properties are analyzed. For instance, the
+size of the condensate, chemical potential, speed of sound, number of
+particles, etc., are deduced. It will be shown that this dipole-dipole
+interaction implies the emergence of anisotropy, for example, in the speed of
+sound. The possible use of this anisotropy as a tool for the analyze of
+dissipative mechanisms, for instance, Landau's criterion for superfluidity,
+will be also discussed.",1306.6680v1
+2013-07-02,Size Dependence of Domain Pattern Transfer in Multiferroic Heterostructures,"Magnetoelectric coupling in multiferroic heterostructures can produce large
+lateral modulations of magnetic anisotropy enabling the imprinting of
+ferroelectric domains into ferromagnetic films. Exchange and magnetostatic
+interactions within ferromagnetic films oppose the formation of such domains.
+Using micromagnetic simulations and a 1-D model, we demonstrate that competing
+energies lead to the breakdown of domain pattern transfer below a critical
+domain width. Moreover, rotation of the magnetic field results in abrupt
+transitions between two scaling regimes with different magnetic anisotropy.",1307.0605v2
+2013-07-24,Measurement of magnetization using domain compressibility in CoFeB films with perpendicular anisotropy,"We present a method to map the saturation magnetization of soft ultrathin
+films with perpendicular anisotropy, and we illustrate it to assess the
+compositional dependence of the magnetization of CoFeB(1 nm)/MgO films. The
+method relies on the measurement of the dipolar repulsion of parallel domain
+walls that define a linear domain. The film magnetization is linked to the
+field compressibility of the domain. The method also yields the minimal
+distance between two walls before their merging, which sets a practical limit
+to the storage density in spintronic devices using domain walls as storage
+entities.",1307.6479v1
+2013-08-12,Anisotropic Heisenberg Model on Core-Shell Structured Nanotube Geometry,"The effect of the anisotropy in the exchange interaction on the critical
+temperature and the order parameter of the anisotropic Heisenberg model on a
+core-shell structured nanotube geometry has been investigated. As a
+formulation, effective field theory with the differential operator technique
+and decoupling approximation within the 4-spin cluster (EFT-4) has been used.
+The variation of the critical temperature with the anisotropy in the exchange
+interaction has been obtained. Besides, suitability of the effective field
+theory in small clusters as a formulation for the Heisenberg nanotube has been
+discussed and it is concluded that minimum size of the cluster is 4-spin
+cluster, which can give the correct critical description of the system.",1308.2511v2
+2013-09-05,Fine structures in the spectrum of the open-boundary Heisenberg chain at large anisotropies,"At large anisotropies, the spectrum of the Heisenberg XXZ spin chain
+separates into `bands' with energies largely determined by the number of domain
+walls. The band structure is richer with open boundary conditions: there are
+more bands and the bands develop intricate fine structures. We characterize and
+explain these structures and substructures in the open-boundary chain. The fine
+structures are explained using degenerate perturbation theory. We also present
+some dynamical consequences of these sub-band structures, through explicit time
+evolution of the wavefunction from initial states motivated by the fine
+structure analysis.",1309.1471v2
+2013-10-23,Magnetization Characteristic of Ferromagnetic Thin Strip by Measuring Anisotropic Magnetoresistance and Ferromagnetic Resonance,"The magnetization characteristic in a permalloy thin strip is investigated by
+electrically measuring the anisotropic magnetoresistance and ferromagnetic
+resonance in in-plane and out-of-plane configurations. Our results indicate
+that the magnetization vector can rotate in the film plane as well as out of
+the film plane by changing the intensity of external magnetic field of certain
+direction. The magnetization characteristic can be explained by considering
+demagnetization and magnetic anisotropy. Our method can be used to obtain the
+demagnetization factor, saturated magnetic moment and the magnetic anisotropy.",1310.6117v1
+2013-10-23,Hamiltonian Theory of Anisotropic Fractional Quantum Hall States,"Rotationally invariant fractional quantum Hall (FQH) states have long been
+understood in terms of composite bosons or composite fermions. Recent
+investigations of both incompressible and compressible states in highly tilted
+fields, which renders them anisotropic, have revealed puzzling features which
+have so far defied quantitative explanation. The author's work with R. Shankar
+in constructing and analyzing an operator-based theory in the rotationally
+invariant FQHE is generalized here to the anisotropic case. We compute the
+effective anisotropies of many principal fraction states in the lowest and the
+first Landau levels and find good agreement with previous theoretical results.
+We compare the effective anisotropy in a model potential with finite sample
+thickness and find good agreement with experimental results.",1310.6215v1
+2013-11-14,Chromo-Natural Model in Anisotropic Background,"In this work we study the chromo-natural inflation model in the anisotropic
+setup. Initiating inflation from Bianchi type-I cosmology, we analyze the
+system thoroughly during the slow-roll inflation, from both analytical and
+numerical points of view. We show that the isotropic FRW inflation is an
+attractor of the system. In other words, anisotropies are damped within few
+$e$--folds and the chromo-natural model respects the cosmic no-hair conjecture.
+Furthermore, we demonstrate that in the slow-roll limit, the anisotropies in
+both chromo-natural and gauge-flation models share the same dynamics.",1311.3361v2
+2013-11-20,"Brownian motion in strongly coupled, anisotropic Yang-Mills plasma: A holographic approach","We employ methods of gauge/string duality to analyze the Brownian motion and
+the concomitant Langevin equation of a heavy quark in a strongly coupled,
+thermal, anisotropic Yang-Mills plasma. We consider fluctuations both along and
+perpendicular to the direction of anisotropy and study the effects of
+anisotropy on the drag coefficient, the diffusion constant and the Langevin
+coefficient for both the directions. We also verify the fluctuation-dissipation
+theorem for Brownian motion in an anisotropic medium.",1311.5023v2
+2013-12-09,"Full susceptibility tensor for localized spin models with S=1, 3/2, 2, 5/2 and with rhombic anisotropy","A general discussion of the simulation procedure of the full susceptibility
+tensor and isothermal magnetization pseudovector for compounds comprising
+weakly-interacting magnetic centers is presented. A single-crystal-sample as
+well as a powder-sample case are considered. The procedure is used to obtain
+explicit expressions for the full susceptibility tensor for spins S=1, 3/2, 2,
+and 5/2 for non-vanishing rhombic local anisotropy and any form of
+spectroscopic tensor.",1312.2401v1
+2014-01-30,Optical fiber Sagnac interferometer for sensing scalar directional refraction: application to magnetochiral birefringence,"We present a set-up dedicated to the measurement of the small scalar
+directional anisotropies associated to the magnetochiral interaction. The
+apparatus, based on a polarization-independent fiber Sagnac interferometer, is
+optimized to be insensitive to circular anisotropies and to residual
+absorption. It can thus characterize samples of biological interests, for which
+the two enantiomers are not available and/or which present poor transmission.
+The signal-to-noise ratio is shown to be limited only by the source intensity
+noise, leading to a detection limit of Df = 500 nrad.Hz-1/2. It yields a limit
+on the magnetochiral index nMC < 4 10-13 T-1 at 1550 nm for the organic
+molecules tested.",1401.7765v1
+2014-02-03,Magnetism and Magnetic Anisotropy of Transition Metal-Phthalocyanine Molecules,"Search for single-molecule magnets (SMMs) with high blocking temperature (TB)
+is urgent for practical applications in magnetic recording, molecular
+spintronics and quantum computing. Based on the First-principles calculations,
+magnetic anisotropy energies (MAE) of the transition metal-Phthalocyanine
+(TM-Pc) molecules are investigated and the mechanism that determines the MAE of
+TM-Pc molecules is established. In particular, colossal MAE > 100 meV can be
+obtained by adding an Os atom on RuPc and OsPc, so these molecules may offer
+ultrahigh thermal stability in devices.",1402.0278v1
+2014-02-05,Tunable Thermal Conduction in Graphane Nanoribbons,"Graphane and graphene are both two-dimensional materials but of different
+bonding configurations, which can result in distinct thermal conduction
+properties. We simulate thermal conduction in graphane nanoribbons (GANRs)
+using the nonequilibrium Green's function method. It is found that GANRs have
+lower ballistic thermal conductance and stronger thermal conductance anisotropy
+than the graphene counterparts. Furthermore, hydrogen vacancies of GANRs
+considerably suppress thermal conduction, accompanied by enhanced thermal
+conductance anisotropy. The tunable thermal conduction, realized by controlling
+the width, edge shape and hydrogen vacancy concentration of GANRs, could be
+useful for thermal management and thermoelectric applications.",1402.1212v1
+2014-02-07,Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at $\sqrt{s_{_{NN}}} = 200$ GeV,"We report on the first measurement of the azimuthal anisotropy ($v_2$) of
+dielectrons ($e^{+}e^{-}$ pairs) at mid-rapidity from $\sqrt{s_{_{NN}}} = 200$
+GeV Au+Au collisions with the STAR detector at RHIC, presented as a function of
+transverse momentum ($p_T$) for different invariant-mass regions. In the mass
+region $M_{ee}\!<1.1$ GeV/$c^2$ the dielectron $v_2$ measurements are found to
+be consistent with expectations from $\pi^{0}$, $\eta$, $\omega$ and $\phi$
+decay contributions. In the mass region $1.1\!<M_{ee}\!<2.9$ GeV/$c^2$, the
+measured dielectron $v_2$ is consistent, within experimental uncertainties,
+with that from the $c\bar{c}$ contributions.",1402.1791v2
+2014-02-18,Effect of radiation-like solid on CMB anisotropies,"We compute the power in the lowest multipoles of CMB anisotropies in the
+presence of radiation-like solid, a hypothetical new kind of radiation with
+nonzero shear modulus. If only the ordinary Sachs-Wolfe effect is taken into
+account, the shear modulus to energy density ratio must be in absolute value of
+order $10^{-5}$ or less for the theory to be consistent with observations
+within cosmic variance. With the integrated Sachs-Wolfe effect switched on, the
+constraint is relaxed almost by two orders of magnitude.",1402.4434v2
+2014-02-26,Spin nematic interaction in multiferroic compound Ba$_{2}$CoGe$_{2}$O$_{7}$,"We demonstrate the existence of the spin nematic interactions in an
+easy-plane type antiferromagnet Ba$_{2}$CoGe$_{2}$O$_{7}$ by exploring the
+magnetic anisotropy and spin dynamics. Combination of neutron scattering and
+magnetic susceptibility measurements reveals that the origin of the in-plane
+anisotropy is an antiferro-type interaction of the spin nematic operator. The
+relation between the nematic operator and the electric polarization in the
+ligand symmetry of this compound is presented. The introduction of the spin
+nematic interaction is useful to understand the physics of spin and electric
+dipole in multiferroic compounds.",1402.6436v1
+2014-03-10,Nematicons in liquid crystals with negative dielectric anisotropy,"We report a theoretical and experimental work on the nematicon in the planar
+cell containing the nematic liquid crystal with negative dielectric anisotropy,
+aligned homeotropically in the presence of an externally applied voltage. The
+formation of the soliton is resulted from the balance between the linear
+difrraction and the nonlocal nonlinearity due to molecular reorientation.",1403.2154v2
+2014-03-14,Cosmology from weak lensing of CMB,"The weak lensing effect on the cosmic microwave background (CMB) induces
+distortions in spatial pattern of CMB anisotropies, and statistical properties
+of CMB anisotropies become a weakly non-Gaussian field. We first summarize the
+weak lensing effect on the CMB (CMB lensing) in the presence of scalar, vector
+and tensor perturbations. Then we focus on the lensing effect on CMB statistics
+and methods to estimate deflection angles and their power spectrum. We end by
+summarizing recent observational progress and future prospect.",1403.3569v1
+2014-03-20,Anisotropic Atom-Surface Interactions in the Casimir-Polder Regime,"The distance-dependence of the anisotropic atom-wall interaction is studied.
+The central result is the 1/z^6 quadrupolar anisotropy decay in the retarded
+Casimir-Polder regime. Analysis of the transition region between non-retarded
+van der Waals regime (in 1/z^3) and Casimir-Polder regime shows that the
+anisotropy cross-over occurs at very short distances from the surface, on the
+order of 0.03 Lambda, where Lambda is the atom characteristic wavelength.
+Possible experimental verifications of this distance dependence are discussed.",1403.5216v1
+2014-03-26,Large Scale Anisotropy of Cosmic Rays and Directional Neutrino Signals from Galactic Sources,"We investigate the neutrino - cosmic ray connection for sources in the Galaxy
+in terms of two observables: the shape of the energy spectrum and the
+distribution of arrival directions. We also study the associated gamma ray
+emission from these sources.",1403.6628v2
+2014-04-04,Thermally assisted domain wall nucleation in perpendicular anisotropy trilayer nanowires,"We study thermally assisted domain wall generation in perpendicular magnetic
+anisotropy CoFeB trilayer nanowires by the effect of Joule heating. The
+anomalous Hall effect is utilized to detect magnetization reversal in order to
+study the domain wall generation. We observe a statistical distribution in the
+switching process which is consistent with the thermal activation process. Our
+results show that the proposed method provides an efficient way for generating
+domain walls in perpendicular magnetic nanowires at predefined locations.",1404.1135v1
+2014-05-01,Multi-region relaxed magnetohydrodynamics with anisotropy and flow,"We present an extension of the multi-region relaxed magnetohydrodynamics
+(MRxMHD) equilibrium model that includes pressure anisotropy and general plasma
+flows. This anisotropic extension to our previous isotropic model is motivated
+by Sun and Finn's model of relaxed anisotropic magnetohydrodynamic equilibria.
+We prove that as the number of plasma regions becomes infinite, our anisotropic
+extension of MRxMHD reduces to anisotropic ideal MHD with flow. The
+continuously nested flux surface limit of our MRxMHD model is the first
+variational principle for anisotropic plasma equilibria with general flow
+fields.",1405.0061v1
+2014-05-03,Axial quadrupole phase of a uniaxial spin-1 magnet,"Uniaxial phase of the axial quadrupole spin-1 magnet in an external magnetic
+field is investigated. A case where the system includes single-ion anisotropy
+and anisotropic biquadratic exchange interaction the most general form, is
+considered. It is proved, that the molecular field approximation of the
+relative magnetization does not depend on temperature and increases linearly
+with the external magnetic field. Two branches of the spin excitation spectrum
+are derived. Condition of mitigation of the spectrum defines the boundary
+between the axial quadrupole and angular phases. The critical temperature of
+the corresponding phase transition depends considerably on the anisotropy
+constants of the biquadratic exchange interaction.",1405.0606v1
+2014-05-08,Anisotropy of acoustooptic figure of merit in optically isotropic media,"We suggest a new approach for analyzing spatial anisotropy of acoustooptic
+figure of merit (AOFM). The relations for the effective elastooptic
+coefficients and the AOFM are derived for all possible types of acoustooptic
+(AO) interactions in optically isotropic media, including non-solid-state and
+solid-state amorphous media, and crystals belonging to the cubic system. Our
+approach allows for finding the optimal geometries of AO interactions
+characterized by the highest AOFM for a given material. The analysis is carried
+out on the examples of cubic KBr and KAl(SO4)2x12H2O crystals which represent
+different subgroups of the cubic symmetry class.",1405.1919v1
+2014-06-04,Growth and superconducting anisotropies of F-substituted LaOBiSe2 single crystals,"F-substituted LaOBiSe2 single crystals were grown using CsCl flux. The
+obtained single crystals showed a plate-like shape with a size of about 1.0 mm
+square. The c-axis lattice constant of the grown crystals was determined to be
+14.114(3) {\AA}. The superconducting critical temperature of the single crystal
+was approximately 3.5 K. The superconducting anisotropies were determined to be
+49 and 24 using the upper critical field and the effective mass model,
+respectively.",1406.0921v1
+2014-06-07,Anisotropy in Inflation with Non-minimal Coupling,"We study a new anisotropic inflation model, with an inflaton field
+nonminimally coupled with the gravity and a vector field. We find that the
+anisotropic attractor solution exists not only in the weak curvature coupling
+limit, but more interestingly in the strong curvature coupling limit as well.
+We show that in the strong curvature coupling limit, the contribution from the
+anisotropy is greatly suppressed.",1406.1874v2
+2014-06-13,Low thermal conductivity and triaxial phononic anisotropy of SnSe,"In this theoretical study, we investigate the origins of the very low thermal
+conductivity of tin selenide (SnSe) using ab-initio calculations. We obtained
+high-temperature lattice thermal conductivity values that are close to those of
+amorphous compounds. We also found a strong anisotropy between the three
+crystallographic axes: one of the in-plane directions conducts heat much more
+easily than the other. Our results are compatible with most of the experimental
+literature on SnSe, and differ markedly from the more isotropic values reported
+by a recent study.",1406.3532v2
+2014-07-04,Hexagonal type Ising nanowire with spin-1 core and spin-2 shell structure,"}Thermodynamic properties and phase diagrams of a mixed spin-(1, 2) Ising
+ferrimagnetic system with single ion anisotropy on hexagonal nanowire are
+studied by using effective-field theory with correlations. The susceptibility,
+internal energy and specific heat of the system are numerically examined and
+some interesting phenomena in these quantities are found. The effect of the
+Hamiltonian parameters on phase diagrams are examined in detail. Besides
+second-order phase transition, lines of first-order transition and tricritical
+points are found. In particular, we found that for some negative values of
+single-ion anisotropies, there exist first-order phase transitions.",1407.1147v1
+2014-07-26,Late time Acceleration and Role of Skewness in Anisotropic models,"We study cosmological models with anisotropy in expansion rates in the
+context of the recent observations predicting an accelerating universe. In the
+absence of any anisotropy in the cosmic fluid, it is shown that the role of
+skewness in directional Hubble rates is crucial in deciding the behavior of the
+model. We find that incorporation of skewness leads to a more evolving
+effective equation of state parameter.",1407.7791v1
+2014-08-04,Universal parameterization of initial-state fluctuations and its applications to event-by-event anisotropy,"We propose Elliptic Power and Power parameterizations for the probability
+distribution of initial state anisotropies in heavy-ion collisions. By assuming
+a linear eccentricity scaling, the new parameterizations can also be applied to
+fluctuations of harmonic flow. In particular, we analyze flow multi-particle
+cumulants and event-by-event distributions, both of which are recently measured
+at the LHC.",1408.0709v1
+2014-08-05,Non-Local Transport Mediated by Spin-Supercurrents,"In thin film ferromagnets with perfect easy-plane anisotropy, the component
+of total spin perpendicular to the easy plane is a good quantum number and the
+corresponding spin supercurrent can flow without dissipation. In this Letter we
+explain how spin supercurrents couple spatially remote spin-mixing vertical
+transport channels, even when easy-plane anisotropy is imperfect, and discuss
+the possibility that this effect can be used to fabricate new types of
+electronic devices.",1408.1100v1
+2014-08-06,Medium-induced optical effects for prompt photons,"Electromagnetic aspects of a QCD matter have been a hot topic in recent
+years. High-energy heavy-ion experiments revealed that flow harmonics of direct
+photons are not explained by most hydrodynamic models. In this work I discuss
+possible effects of refraction by the hot medium since it can work as a lens
+which converts its geometrical anisotropy into momentum anisotropy of photons.
+Then elliptic flow and higher-order harmonics of prompt photons are estimated
+numerically. The results indicate that they could be small but have
+phenomenologically non-trivial consequences.",1408.1410v1
+2014-08-10,Anisotropy universe in doubly warped product scheme,"We study the GMGHS spacetimes to analyze the evolution of the anisotropy
+universe, which can be treated as a doubly warped products manifold possessing
+warping functions (or scale factor) having the Kantowski-Sachs solution which
+represents homogeneous but anisotropically expanding(contracting) cosmology. We
+investigate the curvature associated with three phases in the evolution of the
+universe.",1408.2182v4
+2014-08-21,Evidence of a small crystal field anisotropy in GdCoIn$_5$,"We investigate the effects of an applied magnetic field on the magnetic
+properties of the antiferromagnet GdCoIn$_5$. The prominent anisotropy observed
+in the susceptibility below $T_N$ is rapidly suppressed by a field of just a
+few Tesla. Further evidence of this low energy-scale is obtained from
+magnetoresistance and magnetostriction experiments. The lattice lenght,
+particulary, shows a sudden change below 2 Tesla when the magnetic field is
+applied perpendicular to the crystallographic $\hat{c}$-axis. The experimental
+results as a whole can be attributed to a small but non negligible higher-order
+crystalline electric field.",1408.5156v1
+2014-09-12,Nowhere to hide: closing in on cosmological homogeneity,"Homogeneity is a crucial, but poorly tested, assumption in cosmology. We
+introduce a new approach which allows us to place limits on the presence of
+localized structures within essentially our entire observable volume, using
+cosmic microwave background secondary anisotropies. We find that structures
+cannot exceed roughly 20 times their expected amplitude over most of our
+observable volume. Similarly, we place tight constraints on statistical
+inhomogeneity within our volume, performing the first power spectrum
+reconstruction using secondary anisotropies alone. We find that the standard
+model passes this important new consistency test. Our approach probes
+homogeneity over vastly larger volumes and scales than previous studies based
+on surveys.",1409.3831v1
+2014-09-22,Anisotropic flow of the fireball fed by hard partons,"In nuclear collisions at highest accessible LHC energies, often more than one
+dijet pairs deposit momentum into the deconfined expanding medium. With the
+help of 3+1 dimensional relativistic hydrodynamic simulation we show that this
+leads to measurable contribution to the anisotropy of collective transverse
+expansion. Hard partons generate streams in plasma which merge if they come
+close to each other. This mechanism correlates the resulting contribution to
+flow anisotropy with the fireball geometry and causes an increase of the
+elliptic flow in non-central collisions.",1409.6116v2
+2014-09-22,Are EeV cosmic rays isotropic at intermediate scales?,"We study anisotropy of cosmic rays in the energy range 0.2-1.4 EeV at
+intermediate angular scales using the public data set of the Pierre Auger
+Observatory. At certain scales, the analysis reveals a number of deviations
+from the isotropic distribution with the statistical significance above three
+standard deviations. It also demonstrates that the anisotropy evolves with
+energy. If confirmed with the complete Auger or Telescope Array data sets, the
+result can shed new light on the structure of galactic magnetic fields and the
+problem of transition from galactic to extragalactic cosmic rays.",1409.6138v1
+2014-09-30,Relativistic Viscous Universe Models,"The research on relativistic universe models with viscous fluids is reviewed.
+Viscosity may have been of significance during the early inflationary era, and
+may also be of importance for the late time evolution of the Universe. Bulk
+viscosity and shear viscosity cause exponential decay of anisotropy, while
+nonlinear viscosity causes power-law decay of anisotropy. We consider also the
+influence from turbulence, in connection with future singularities of the
+universe (Big Rip and Little Rip). Finally, we review some recent developments
+of causal cosmology theories.",1409.8561v1
+2014-10-13,Eilenberger theory and London theory for transverse components of flux line lattice form factors in uniaxial superconductors,"We theoretically study the magnetic field orientation dependence of
+longitudinal and transverse flux line lattice form factors in uniaxial
+superconductors with anisotropy ratio corresponding to YBa_2_Cu_3_O_{7-delta}.
+We discuss influences of the anisotropy ratio of coherence length, and
+differences between the s-wave and the d_{x^2-y^2}-wave pairings. The
+calculations are performed by two methods, the Eilenberger theory and the
+London theory comparatively, and we study the cutoff function of the extended
+London theory, which will be helpful in the analysis of the small angle neutron
+scattering in the vortex states.",1410.3204v1
+2014-10-14,Skyrmion-like states in multilayer exchange coupled ferromagnetic nanostructures with distinct anisotropy directions,"We report the experimental observation of magnetic skyrmion-like states in
+patterned ferromagnetic nanostructures consisting of perpendicular magnetized
+Co/Pt multilayer film exchange coupled with Co nanodisks in vortex state. The
+magnetic force microscopy and micromagnetic simulations show that depending on
+the magnitude of Co/Pt perpendicular anisotropy in these systems two different
+modes of skyrmion formation are realized.",1410.4174v1
+2014-10-23,Conductivity anisotropy helps to reveal the microscopic structure of a density wave at imperfect nesting,"Superconductivity or metallic state may coexist with density wave ordering at
+imperfect nesting of the Fermi surface. In addition to the macroscopic spatial
+phase separation, there are, at least, two possible microscopic structures of
+such coexistence: (i) the soliton-wall phase and (ii) the ungapped
+Fermi-surface pockets. We show that the conductivity anisotropy allows to
+distinguish between these two microscopic density-wave structures. The results
+obtained may help to analyze the experimental observations in layered organic
+metals (TMTSF)$_{2}$PF$_{6}$, (TMTSF)$_{2}$ClO$_{4}$, $\alpha
+$-(BEDT-TTF)$_{2}$KHg(SCN)$_{4}$ and in other compounds.",1410.6314v1
+2014-10-31,Elliptic flow of thermal photons in chemically non-equilibrated QCD medium,"Heavy-ion experiments have recently revealed that azimuthal momentum
+anisotropy -- elliptic flow -- of direct photons from a QCD medium is a few
+times larger than hydrodynamic predictions. I present a possible explanation
+for the enhancement based on late quark chemical equilibration. The color glass
+theory indicates that the medium is initially gluon-rich. Thermal photons are
+then mainly produced after quarks are produced, at which point large flow
+anisotropy is developed. The numerical estimations indicate that slow chemical
+equilibration visibly enhances the elliptic flow of thermal photons.",1410.8621v1
+2014-12-05,A Relativistic Plasma Polarizer: Impact of Temperature Anisotropy on Relativistic Transparency,"3D particle-in-cell simulations demonstrate that the enhanced transparency of
+a relativistically hot plasma is sensitive to how the energy is partitioned
+between different degrees of freedom. For an anisotropic electron distribution,
+propagation characteristics, like the critical density, will depend on the
+polarization of the electromagnetic wave. Despite the onset of the Weibel
+instability in such plasmas, the anisotropy can persist long enough to affect
+laser propagation. This plasma can then function as a polarizer or a waveplate
+to dramatically alter the pulse polarization.",1412.1865v1
+2015-02-03,Modeling anisotropic charged neutron star in isotropic coordinates,"We present a spherically symmetric solution of the general relativistic field
+equations in isotropic coordinates for charged fluid with pressure anisotropy,
+compatible with a super dense star modeling. Further, we have constructed an
+anisotropic model of super dense star with all degree of suitability. We also
+observed that by increasing anisotropy, the maximum mass of super dense stars
+also decreases.",1502.03378v1
+2015-02-24,Spin rectification for collinear and non-collinear magnetization and external magnetic field configurations,"Spin rectification in a single crystal Fe/Au/Fe sandwich is electrically
+detected for collinear and non-collinear magnetization and external magnetic
+field configurations. The line shape, line width and signal polarity are
+analysed. The spin rectication theory has been much extended by taking the
+magneto-crystalline anisotropy and shape anisotropy into account, which
+explained non-collinear resonances and agrees very well with experimental data.
+Thus, a comprehensive understanding of spin rectification in ferromagnetic
+metal was demonstrated in this work.",1502.06859v1
+2015-04-20,URu2Si2: hidden order and amplitude of quantum oscillations,"It is shown that the hidden ordered (HO) state in heavy fermionic metal
+URu2Si2 is either nonconventional charge density wave (CDW) or
+antiferroelectric (AFE) commensurate ordering. Similar to antiferromagnetic
+(AF) order an antiferroelectric order creates momentum dependence of conducting
+electrons $g$-factor. This even modest anisotropy along with the anisotropy of
+heavy cyclotron mass can produce multiple effect of so called zero-spin
+splitting in the amplitude of the de Haas - van Alphen and the Shubnikov - de
+Haas signals as function of direction of magnetic field.",1504.05020v2
+2015-04-29,"L1$_0$ stacked binaries as candidates for hard magnets: FePt, MnAl and MnGa","A novel strategy of stacking binary magnets to enhance the magneto
+crystalline anisotropy is explored. This strategy is used in the search for
+hard magnets by studying FePt/MnGa and FePt/MnAl stacks. The choice of these
+binaries is motivated by the fact that they already possess large magneto
+crystalline anisotropy. Several possible alternative structures for these
+materials are explored in order to reduce the amount of Pt owing to its high
+cost.",1504.07827v1
+2015-05-15,Dilepton production from the quark-gluon plasma using leading-order (3+1)D anisotropic hydrodynamics,"Dilepton production from the quark-gluon plasma (QGP) phase of
+ultra-relativistic heavy-ion collisions is computed using the leading-order
+(3+1)-dimensional anisotropic hydrodynamics. It is shown that high-energy
+dilepton spectrum is sensitive to the initial local-rest-frame momentum-space
+anisotropy of the QGP. Our findings suggest that it may be possible to
+constrain the early-time momentum-space anisotropy in relativistic heavy-ion
+collisions using high-energy dilepton yields.",1505.04018v1
+2015-05-26,Quantum correlations in Ising-XYZ diamond chain structure under an external magnetic field,"In this paper, we consider an entangled Ising-XYZ diamond chain structure.
+Quantum correlations for this model is investigated by using of quantum discord
+and trace distance discord. Quantum correlations is obtained for different
+values of the anisotropy parameter, magnetic field and temperature. By
+comparison between quantum correlations, we show trace distance discord is
+always larger than quantum discord. Finally, some novel effects, such as
+increasing the quantum correlations with temperature and constructive role of
+anisotropy parameter which may paly to the quantum correlations were observed.",1505.06820v2
+2015-05-27,Excitation of magnetic precession in bismuth iron garnet via a polarization-independent impulsive photomagnetic effect,"A polarization-independent, nonthermal optical effect on the magnetization in
+bismuth iron garnet is found, in addition to the circular
+polarization-dependent inverse Faraday effect and the linear
+polarization-dependent photoinduced magnetic anisotropy. Its impulsive
+character is demonstrated by the field dependence of the amplitude of the
+resulting precession, which cannot be explained by a long-living photo or
+heat-induced anisotropy.",1505.07447v1
+2015-06-09,Hysteresis behaviors of a spin-1 anisotropic Heisenberg model,"The hysteresis behaviors of anisotropic S-1 Heisenberg model have been
+studied within the effective field theory with two spin cluster. After giving
+the phase diagrams, the effect of the crystal field and anisotropy in the
+exchange interaction on the hysteresis loops have been determined. One
+important finding is double hysteresis loop behavior of the system in the low
+temperature and negative crystal field region, which disappears with the
+decreasing anisotropy in the exchange interaction. This behavior was carefully
+investigated and physical explanation has also been given.",1506.02859v1
+2015-06-24,Inflation after Planck and BICEP2,"We discuss the inflationary paradigm, how it can be tested, and how various
+models of inflation fare in the light of data from Planck and BICEP2. We
+introduce inflation and reheating, and discuss temperature and polarisation
+anisotropies in the cosmic microwave background radiation due to quantum
+fluctuations during inflation. Fitting observations of the anisotropies with
+theoretical realisations obtained by varying various parameters of the
+curvature power spectrum and cosmological parameters enables one to obtain the
+allowed ranges of these parameters. We discuss how to relate these parameters
+to inflation models which allows one to rule in or out specific models of
+inflation.",1506.07433v1
+2015-07-02,Flow anisotropies due to momentum deposition from hard partons,"In nuclear collisions at the LHC large number of hard partons are created in
+initial partonic interactions, so that it is reasonable to suppose that they do
+not thermalise immediately but deposit their energy and momentum later into the
+evolving hot quark-gluon fluid. We show that this mechanism leads to
+contribution to flow anisotropies at all orders which are non-negligible and
+should be taken into account in realistic simulations.",1507.00499v1
+2015-09-03,Dynamic Entanglement Evolution of Two-qubit XYZ Spin Chain in Markovian Environment,"We propose a new approach called Ket-Bra Entangled State (KBES) Method for
+converting master equation into Schr\""{o}dinger-like equation. With this
+method, we investigate decoherence process and entanglement dynamics induced by
+a $2$-qubit spin chain that each qubit coupled with reservoir. The spin chain
+is an anisotropy $XYZ$ Heisenberg model in the external magnetic field $B$, the
+corresponding master equation is solved concisely by KBES method; Furthermore,
+the effects of anisotropy, temperature, external field and initial state on
+concurrence dynamics is analyzed in detail for the case that initial state is
+Extended Wenger-Like(EWL) state. Finally we research the coherence and
+concurrence of the final state (namely the density operator for time tend to
+infinite)",1509.01001v1
+2015-09-16,High-speed measurement of rotational anisotropy nonlinear optical harmonic generation using position sensitive detection,"We present a method of performing high-speed rotational anisotropy nonlinear
+optical harmonic generation experiments at rotational frequencies of several
+hertz by projecting the harmonic light reflected at different angles from a
+sample onto a stationary position sensitive detector. The high rotational speed
+of the technique, $10^3$ to $10^4$ times larger than existing methods, permits
+precise measurements of the crystallographic and electronic symmetries of
+samples by averaging over low frequency laser power, beam pointing, and pulse
+width fluctuations. We demonstrate the sensitivity of our technique by
+resolving the bulk four-fold rotational symmetry of GaAs about its [001] axis
+using second harmonic generation.",1509.04779v1
+2015-09-17,On anisotropic black branes with Lifshitz scaling,"In this paper, based on the method of scalar perturbations, we construct the
+\textit{anisotropic} charged Lifshitz background perturbatively upto leading
+order in the anisotropy. We perform our analysis both in the extremal as well
+as in the non extremal limit. Finally, we probe the so called superfluid phase
+of the boundary theory and explore the effects of anisotropy on the
+superconducting condensate.",1509.05229v2
+2015-10-11,Crystal Field Excitations in Breathing Pyrochlore Antiferromagnet Ba3Yb2Zn5O11,"Inelastic neutron scattering measurement is performed on a breathing
+pyrochlore antiferromagnet Ba3Yb2Zn5O11. The observed dispersionless
+excitations are explained by a crystalline electric field (CEF) Hamiltonian of
+Kramers ion Yb3+ of which the local symmetry exhibits C3v point group symmetry.
+The magnetic susceptibility previously reported is consistently reproduced by
+the energy scheme of the CEF excitations. The obtained wave functions of the
+ground state Kramers doublet exhibit the planer-type anisotropy. The result
+demonstrates that Ba3Yb2Zn5O11 is an experimental realization of breathing
+pyrochlore antiferromagnet with a pseudospin S = 1/2 having easy-plane
+anisotropy.",1510.03049v1
+2015-10-13,Probing strongly coupled anisotropic plasmas from higher curvature gravity,"We consider five-dimensional AdS-axion-dilaton gravity with a Gauss-Bonnet
+term and use a black brane solution displaying spatial anisotropy as the
+gravity dual of a strongly coupled anisotropic plasma. We compute several
+observables relevant to the study of the plasma, namely, the drag force, the
+jet quenching parameter, the quarkonium potential and the thermal photon
+production. The effects of higher derivative corrections and of the anisotropy
+are discussed and compared with previous results.",1510.03774v3
+2015-10-16,Reaction diffusion dynamics and the Schryer-Walker solution for domain walls of the Landau-Lifshitz-Gilbert equation,"We study the dynamics of the equation obtained by Schryer and Walker for the
+motion of domain walls. The reduced equation is a reaction diffusion equation
+for the angle between the applied field and the magnetization vector. If the
+hard axis anisotropy $K_d$ is much larger than the easy axis anisotropy $K_u$,
+there is a range of applied fields where the dynamics does not select the
+Schryer-Walker solution. We give analytic expressions for the speed of the
+domain wall in this regime and the conditions for its existence.",1510.04927v1
+2015-11-14,Incoherent magnetization dynamics in strain mediated switching of magnetostrictive nanomagnets,"Micromagnetic studies of the magnetization change in magnetostrictive
+nanomagnets subjected to stress are performed for nanomagnets of different
+sizes. The interplay between demagnetization, exchange and stress anisotropy
+energies is used to explain the rich physics of size-dependent magnetization
+dynamics induced by modulating stress anisotropy in planar nanomagnets. These
+studies have important implications for strain mediated ultralow energy
+magnetization change in nanomagnets and its application in energy-efficient
+nanomagnetic computing systems.",1511.04617v1
+2015-11-21,Hybridization and anisotropy in the exchange interaction in 3D Dirac semimetals,"We study the Ruderman-Kittel-Kasuya-Yosida interaction in 3D Dirac
+semimetals. Using retarded Green's functions in real space, we obtain and
+analyze asymptotic expressions for the interaction, with magnetic impurities at
+different distances and relative angle with respect to high symmetry directions
+on the lattice. We show that the Fermi velocity anisotropy in these materials
+produces a strong renormalization of the magnitude of the interaction, as well
+as a correction to the frequency of oscillation in real space. Hybridization of
+the impurities to different conduction electron orbitals are shown to result in
+interesting anisotropic spin-spin interactions which can generate spiral spin
+structures in doped samples.",1511.06933v1
+2015-12-01,Wave Propagation in Undulated Structural Lattices,"This work investigates wave propagation in undulated square structural
+lattices. The undulated pattern is obtained by imposing an initial curvature to
+the lattice's elements. The study considers both periodic undulated structures,
+in which the undulation is uniform throughout the structure as well as graded
+undulated patterns, in which the undulation is modulated within the lattice.
+Undulation is specifically considered in relation to its ability to induce
+anisotropy in the equivalent mechanical properties and to break the symmetry of
+the straight square lattice. Results show that wave motion is inhibited within
+specified frequency ranges owing to the generation of band gaps, and in
+specific directions as a result of the undulation-induced anisotropy.",1512.00114v1
+2015-12-07,Anisotropy of the magnetic properties of the FeTe0.65Se0.35 superconductor,"The magnetization anisotropy of a layered superconductor FeTe0.65Se0.35
+sample is experimentally studied in a magnetic field directed either along the
+layers of the plane, or perpendicular to them. The value of the vortex pinning
+potential in a weak magnetic field, and the critical current density ratio are
+determined for these directions. The results are discussed within the framework
+of presenting the sample as layers of fine single crystals, divided by weak
+interlayer superconducting bonds with magnetic inclusions.",1512.02027v1
+2015-12-09,Scaling laws for the critical current density in anisotropic biaxial superconductors,"To understand the anisotropy of flux pinning and critical current density in
+technological superconductors, the scaling law for the anisotropy of
+single-vortex collective pinning in uniaxial superconductors is extended to
+flux-bundle collective pinning in biaxial superconductors. The scaling results
+show that in a system of random uncorrected point defects, the critical current
+density is described by a unified function with the magnetic field of the
+scaled isotropic superconductor. The obtained angular dependence of the
+critical current density depicts the main features of experimental
+observations, considering possible corrections due to the strong-pinning
+interaction.",1512.02774v1
+2015-12-19,The effect of momentum deposition during fireball evolution on flow anisotropy,"The highest LHC energies give rise to production of many pairs of hard
+partons which deposit four-momentum into the expanding fireball matter. We
+argue that it is necessary to include momentum deposition during fireball
+evolution into 3+1 dimensional hydrodynamic simulations of the collision. This
+influence cannot be accounted for simply by modifying initial conditions of the
+simulation. The resulting contribution to flow anisotropy is correlated with
+the fireball geometry and causes an increase of the elliptic flow in
+non-central collisions. The results are presented for various scenarios with
+energy and momentum deposition to clearly demonstrate this effect.",1512.06215v2
+2016-01-18,Anisotropic solutions in f(R) Gravity,"Anisotropic cosmological models are investigated in the frame work of $f(R)$
+gravity in the metric formalism. Plane symmetric models are considered to
+incorporate anisotropy in the expansion rates along different spatial
+directions. The anisotropy in expansion rates are assumed to be maintained
+throughout the cosmic evolution. Two accelerating models are constructed by
+considering different functional forms for f(R). The viability of these models
+are tested through a stability analysis.",1601.05019v1
+2016-02-26,Reorientation of quantum Hall stripes within a partially filled Landau level,"We investigate the effect of the filling factor on transport anisotropies,
+known as stripes, in high Landau levels of a two-dimensional electron gas. We
+find that at certain in-plane magnetic fields, the stripes orientation is
+sensitive to the filling factor within a given Landau level. This sensitivity
+gives rise to the emergence of stripes away from half-filling while an
+orthogonally-oriented, native stripes reside at half-filling. This switching of
+the anisotropy axes within a single Landau level can be attributed to a strong
+dependence of the native symmetry breaking potential on the filling factor.",1602.08395v1
+2016-04-03,Soliton collisions in soft magnetic nanotube with uniaxial anisotropy,"The structure of stable magnetic solitons of various orders in soft magnetic
+nanotube with uniaxial magnetic anisotropy has been studied using numerical
+simulation. Solitons of even order are immobile in axially applied magnetic
+field. Odd solitons show decreased mobility with respect to that of head-to
+head domain wall. Solitons of various orders can participate in nanotube
+magnetization reversal process. Various coalescence and decomposition processes
+in soliton assembly are considered. It is shown that the general magnetization
+state of magnetic nanotube consists of chains of magnetic solitons of various
+orders.",1604.00614v1
+2016-04-17,Angular anisotropy of time delay in XUV/IR photoionization of H$_2^+$,"We develop a novel technique for modeling of atomic and molecular ionization
+in superposition of XUV and IR fields with characteristics typical for
+attosecond streaking and RABBITT experiments. The method is based on solving
+the time-dependent Schr\""odinger equation in the coordinate frame expanding
+along with the photoelectron wave packet. The efficiency of the method is
+demonstrated by calculating angular anisotropy of photoemission time delay of
+the H$_2^+$ ion in a field configuration of recent RABBITT experiments.",1604.04938v1
+2016-04-19,Ultrahigh Energy Cosmic Rays: A Galactic Origin?,"It is suggested that essentially all of the UHECRs we detect, including those
+at the highest energy, originate in our Galaxy. It is shown that even if the
+density of sources decreases with Galactic radius, then the anisotropy and
+composition can be understood. Inward anisotropy, as recently reported by the
+Auger collaboration can be understood as drift along the current sheet of
+UHECRs originating outside the solar circle, as predicted in Kumar and Eichler
+(2014), while those originating within the solar circle exit the Galaxy at high
+latitudes.",1604.05721v1
+2016-05-03,Ion collisional transport coefficients in the solar wind at 1 AU,"Proton and alpha particle collisional transport coefficients (isotropization,
+relative deceleration frequencies and heating rates) at 1 AU are quantified
+using the WIND/SWE data. In agreement with previous studies the ion-ion Coulomb
+collisions are generally important for slow solar wind streams and tend to
+reduce the temperature anisotropies, the differential streaming and the
+differences between proton and alpha particle temperatures. In slow solar wind
+streams the Coulomb collisions between protons and alpha particles are
+important for the overall proton energetics as well as for the relative
+deceleration between the two species. It is also shown that ion temperature
+anisotropies and differential streaming need to be generally taken into account
+for evaluation of the collisional transport coefficients.",1605.00804v1
+2016-05-11,Proton structure in high-energy high-multiplicity p-p collisions,"A few-body proton image, expected to be derivable from QCD in the
+renormalization group procedure for effective particles, is used within the
+Monte Carlo Glauber model to calculate the anisotropy coefficients in the
+initial collision-state of matter in high-energy high-multiplicity
+proton-proton interaction events. We estimate the ridge-like correlations in
+the final hadronic state by assuming their proportionality to the initial
+collision-state anisotropy. In our estimates, some distinct few-body proton
+structures appear capable of accounting for the magnitude of p-p ridge effect,
+with potentially discernible differences in dependence on multiplicity.",1605.03488v1
+2016-05-28,Unidirectional superscattering by multilayered cavities of effective radial anisotropy,"We achieve unidirectional forward superscattering by multilayered spherical
+cavities which are effectively radially anisotropic. It is demonstrated that,
+relying on the large effective anisotropy, the electric and magnetic dipoles
+can be tuned to spectrally overlap in such cavities, which satisfies the
+Kerker's condition of simultaneous backward scattering suppression and forward
+scattering enhancement. We show such scattering pattern shaping can be obtained
+in both all-dielectric and plasmonic multilayered cavities, and believe that
+the mechanism we have revealed provides extra freedom for scattering shaping,
+which may play a significant role in many scattering related applications and
+also in optoelectronic devices made up of intrinsically anisotropic two
+dimensional materials.",1605.08895v1
+2016-06-21,Characterization of the scintillation anisotropy in crystalline stilbene scintillator detectors,"This paper reports a series of measurements that characterize the directional
+dependence of the scintillation response of crystalline melt-grown and
+solution-grown stilbene to incident DT and DD neutrons. These measurements give
+the amplitude and pulse shape dependence on the proton recoil direction over
+one hemisphere of the crystal, confirming and extending previous results in the
+literature for melt-grown stilbene and providing the first measurements for
+solution-grown stilbene. In similar measurements of liquid and plastic
+detectors, no directional dependence was observed, confirming the hypothesis
+that the anisotropy in stilbene and other organic crystal scintillators is a
+result of internal effects due to the molecular or crystal structure and not an
+external effect on the measurement system.",1606.06715v1
+2016-06-30,The effect of minijet on hadron spectra and azimuthal anisotropy in heavy-ion collisions,"Here I review the transverse momentum distributions of identified hadrons
+produced in Au-Au collisions at RHIC and Pb-Pb collisions at LHC in the
+framework of recombination model. Minijets play an important role in generating
+shower partons in the intermediate $p_T$ region. At LHC, the resultant soft
+shower partons are even found to dominate over the thermal partons in the
+non-strange sector. The azimuthal anisotropy of the produced hadrons could also
+be explained as the consequence of the effects of minijets. Harmonic analysis
+of the $\phi$ dependence leads to $v_n(p_T, b)$ that can be well produced
+without reference to flow.",1606.09373v1
+2016-07-28,The random anisotropy model revisited,"We revisit the thermodynamic behavior of the random-anisotropy O($N$) model
+by investigating its large-$N$ limit. We focus on the system at zero
+temperature where the mean-field-like artifacts of the large-$N$ limit are less
+severe. We analyze the connection between the description in terms of
+self-consistent Schwinger-Dyson equations and the functional renormalization
+group. We provide a unified description of the phase diagram and critical
+behavior of the model and clarify the nature of the possible ""glassy"" phases.
+Finally we discuss the implications of our findings for the finite-$N$ and
+finite-temperature systems.",1607.08515v1
+2016-10-21,Concurrency of anisotropy and spatial dispersion in low refractive index dielectric composites,"The article demonstrates uncommon manifestation of spatial dispersion in low
+refractive index contrast 3D periodic dielectric composites with periods of
+about one tenth of the wavelength. First principles simulations by the well
+established plane wave method reveal that spatial dispersion leads to
+appearance of additional optical axes and can compensate anisotropy in certain
+directions.",1610.06828v2
+2016-11-04,Spontaneous generation of a temperature anisotropy in a strongly coupled magnetized plasma,"A magnetic field was recently shown to enhance field-parallel heat conduction
+in a strongly correlated plasma whereas cross-field conduction is reduced. Here
+we show that in such plasmas, the magnetic field has the additional effect of
+inhibiting the isotropization process between field-parallel and cross-field
+temperature components thus leading to the emergence of strong and long-lived
+temperature anisotropies when the plasma is locally perturbed. An extended heat
+equation is shown to describe this process accurately.",1611.01397v1
+2016-11-29,Odd Azimuthal Anisotropy of the Glasma for pA Scattering,"In this paper we analytically extract the odd azimuthal anisotropy in the
+Classical Yang-Mills equations for the Glasma for pA collisions. We compute the
+first non-trivial term in the expansion of the proton sources of color charge.
+The computation is valid in the limit of a large nucleus when the produced
+particle momenta are larger than the saturation momentum of the proton.",1611.09870v4
+2016-11-30,Two-dimensional Phononic Crystals with Acoustic-Band Negative Refraction,"A two-dimensional phononic crystal (PC) can exhibit longitudinal-mode
+negative energy refraction on its lowest (acoustical) frequency pass band. The
+effective elastodynamic properties of a typical PC are calculated and it is
+observed that the components of the effective density tensor can achieve
+negative values at certain low frequencies on the acoustical branches for the
+longitudinal-mode pass-band, and that negative refraction may be accompanied by
+either positive or negative effective density. Furthermore, such a PC has a
+high anisotropy ratio at certain low frequencies, offering potential for
+application to acoustic cloaking where effective material anisotropy is
+essential.",1612.00037v1
+2016-11-28,On Cracking of Charged Anisotropic Polytropes,"Recently in \cite{34}, the role of electromagnetic field on the cracking of
+spherical polytropes has been investigated without perturbing charge parameter
+explicitly. In this study, we have examined the occurrence of cracking of
+anisotropic spherical polytropes through perturbing parameters like anisotropic
+pressure, energy density and charge. We consider two different types of
+polytropes in this study. We discuss the occurrence of cracking in two
+different ways $(i)$ by perturbing polytropic constant, anisotropy and charge
+parameter $(ii)$ by perturbing polytropic index, anisotropy and charge
+parameter for each case. We conclude that cracking appears for a wide range of
+parameters in both cases. Also, our results are reduced to \cite{33} in the
+absence of charge.",1612.00290v1
+2016-12-22,Spin Superfluidity in Biaxial Antiferromagnetic Insulators,"Antiferromagnets may exhibit spin superfluidity since the dipole interaction
+is weak. We seek to establish that this phenomenon occurs in insulators such as
+NiO, which is a good spin conductor according to previous studies. We
+investigate nonlocal spin transport in a planar antiferromagnetic insulator
+with a weak uniaxial anisotropy. The anisotropy hinders spin superfluidity by
+creating a substantial threshold that the current must overcome. Nevertheless,
+we show that applying a high magnetic field removes this obstacle near the
+spin-flop transition of the antiferromagnet. Importantly, the spin
+superfluidity can then persist across many micrometers, even in dirty samples.",1612.07440v2
+2017-01-01,Electrical Transport of perpendicularly magnetized L10-MnGa and MnAl films,"Ferromagnetic films of L10-ordered MnGa and MnAl that exhibit giant
+perpendicular magnetic anisotropy and great controllability in the magnetism
+and structural disorders show promise not only in the applications in magnetic
+recording, permanent magnets and spintronics, but also in controllable studies
+of disorder-relevant electrical transport phenomena. In this article, we review
+the intriguing experimental observations of the orbital two-channel Kondo
+effect and anomalous Hall effect in L10-ordered MnGa and MnAl thin films with
+perpendicular magnetic anisotropy. We also give a perspective with regards to
+the future technological and fundamental applications of these perpendicularly
+magnetized Mn-based binary alloy films.",1701.00191v1
+2017-02-16,Domain wall nucleation in ferromagnetic nanowire with perpendicular magnetization stimulated by stray field of V-shaped magnetic particle,"We report the results of micromagnetic simulations of domain wall (DW)
+nucleation and pinning/depinning processes in ferromagnetic planar structure
+consisting of nanowire (NW) with perpendicular anisotropy and special V-shaped
+nanoparticle (NP) with in-plane anisotropy located on top of NW. The
+magnetization reversal features of this system in an external magnetic field
+are investigated depending on the direction of particle magnetic moment.
+Possible variants of magnetic logic cells (LCs) based on such system are
+discussed.",1702.05416v1
+2017-02-19,Width of the confinement-induced resonance in a quasi-one-dimensional trap with transverse anisotropy,"We theoretically study the width of the s-wave confinement-induced resonance
+(CIR) in quasi-one-dimensional atomic gases under tunable transversely
+anisotropic confinement. We find that the width of the CIR can be tuned by
+varying the transverse anisotropy. The change in the width of the CIR can
+manifest itself in the position of the discontinuity in the interaction energy
+density, which can be probed experimentally.",1702.05761v3
+2017-03-10,Effects on the CMB from magnetic field dissipation before recombination,"Magnetic fields present before decoupling are damped due to radiative
+viscosity. This energy injection affects the thermal and ionization history of
+the cosmic plasma. The implications for the CMB anisotropies and polarization
+are investigated for different parameter choices of a non helical stochastic
+magnetic field. Assuming a Gaussian smoothing scale determined by the magnetic
+damping wave number at recombination it is found that magnetic fields with
+present day strength less than 0.1 nG and negative magnetic spectral indices
+have a sizeable effect on the CMB temperature anisotropies and polarization.",1703.03650v1
+2017-04-26,Superscattering pattern shaping for radially anisotropic nanowires,"We achieve efficient shaping of superscattering by radially anisotropic
+nanowires relying on resonant multipolar interferences. It is shown that the
+radial anisotropy of refractive index can be employed to resonantly overlap
+electric and magnetic multipoles of various orders, and as a result effective
+superscattering with different engineered angular patterns can be obtained. We
+further demonstrate that such superscattering shaping relying on unusual radial
+anisotropy parameters can be directly realised with isotropic multi-layered
+nanowires, which may shed new light to many fundamental researches and various
+applications related to scattering particles.",1704.07994v2
+2017-05-04,Reduced models for ferromagnetic thin films with periodic surface roughness,"We investigate the influence of periodic surface roughness in thin
+ferromagnetic films on shape anisotropy and magnetization behavior inside the
+ferromagnet. Starting from the full micromagnetic energy and using methods of
+homogenization and $\Gamma$-convergence we derive a two dimensional local
+reduced model. Investigation of this model provides an insight on the formation
+mechanism of {\it perpendicular magnetic anisotropy} and uniaxial anisotropy
+with an {\it arbitrary} preferred direction of magnetization.",1705.01742v1
+2017-06-10,Dynamical features of an anisotropic cosmological model,"The dynamical features of Bianchi type $VI_h$ $(BVI_h)$ universe are
+investigated in $f(R,T)$ theory of gravity. The field equations and the
+physical properties of the model are derived considering a power law expansion
+of the universe. The effect of anisotropy on the dynamics of the universe as
+well on the energy conditions are studied. The assumed anisotropy of the model
+is found to have substantial effects on the energy condition and dynamical
+parameters.",1706.03767v2
+2017-06-15,Can decaying particle explain cosmic infrared background excess?,"Recently the CIBER experiment measured the diffuse cosmic infrared background
+(CIB) flux and claimed an excess compared with integrated emission from
+galaxies. We show that the CIB spectrum can be fitted by the additional photons
+produced by the decay of a new particle. However, it also contributes too much
+to the anisotropy of the CIB, which is in contradiction with the anisotropy
+measurements by the CIBER and Hubble Space Telescope.",1706.04921v1
+2017-06-16,Nanoconstriction spin-Hall oscillator with perpendicular magnetic anisotropy,"We experimentally study spin-Hall nano-oscillators based on [Co/Ni]
+multilayers with perpendicular magnetic anisotropy. We show that these devices
+are capable of single-frequency auto-oscillations at current densities
+comparable to those in the in-plane magnetized oscillators. The demonstrated
+oscillators exhibit large magnetization precession amplitudes, and their
+oscillation frequency is highly tunable by the electric current. These features
+make them promising for applications in high-speed integrated microwave
+circuits.",1706.05302v1
+2017-06-21,Quantum Phase Transition in the Twisted Three-Leg Spin Tube,"We investigate the spin-1/2 twisted three-leg antiferromagnetic quantum spin
+tube in the presence of the easy-plane anisotropy, using the numerical
+diagonalization of finite-size clusters. And we observe cases of the existence
+and the absence of magnetization plateau at 1/3 height of saturation
+magnetization when the anisotropy is tuned. The
+phenomenological-renormalization analysis indicates a quantum phase transition
+between the 1/3 magnetization plateau phase and the plateauless one. The phase
+diagram is also presented.",1706.06947v1
+2017-08-10,Control of the gyration dynamics of magnetic vortices by the magnetoelastic effect,"The influence of a strain-induced uniaxial magnetoelastic anisotropy on the
+magnetic vortex core dynamics in microstructured magnetostrictive
+Co$_{40}$Fe$_{40}$B$_{20}$ elements was investigated with time-resolved
+scanning transmission x-ray microscopy. The measurements revealed a
+monotonically decreasing eigenfrequency of the vortex core gyration with the
+increasing magnetoelastic anisotropy, which follows closely the predictions
+from micromagnetic modeling.",1708.03123v1
+2017-08-16,The Microscopic Model of BiFeO$_3$,"Many years and great effort have been spent constructing the microscopic
+model for the room temperature multiferroic BiFeO3 However, earlier models
+implicitly assumed that the cycloidal wavevector q was confined to one of the
+three-fold symmetric axis in the hexagonal plane normal to the electric
+polarization. Because recent measurements indicate that q can be rotated by a
+magnetic field, it is essential to properly treat the anisotropy that confines
+q at low fields. We show that the anisotropy energy $-K_3 S^6 \sin^6 \theta
+\cos 6 \phi $ confines the wavevectors q to the three-fold axis $\phi =0$ and
+$+-2 \pi/3$ within the hexagonal plane with $\theta = \pi /2$.",1708.04925v1
+2017-08-25,"Classification of symmetry properties of waveguide modes in presence of gain/losses, anisotropy/bianisotropy, or continuous/discrete rotational symmetry","We study the symmetric properties of waveguide modes in presence of
+gain/losses, anisotropy/bianisotropy, or continuous/discrete rotational
+symmetry. We provide a comprehensive approach to identity the modal symmetry by
+constructing a $4\times4$ waveguide Hamiltonian and searching the symmetric
+operation in association with the corresponding waveguides. We classify the
+chiral/time reversal/parity/parity time/rotational symmetry for different
+waveguides, and provide the criterion for the aforementioned symmetry
+operations. Lastly, we provide examples to illustrate how the symmetry
+operations can be used to classify the modal properties from the symmetric
+relation between modal profiles of several different waveguides.",1708.07600v1
+2017-08-27,Direct Photon Production and Azimuthal Anisotropy at Low Transverse Momentum measured in PHENIX,"The PHENIX experiment discovered a large excess of low-$p_{T}$ direct photons
+in Au+Au collisions at 200 GeV compared to reference p+p collisions, which has
+been attributed to thermal radiation from the medium produced in the
+collisions. At the same time the excess photons show a large azimuthal
+anisotropy, expressed as Fourier coefficients $v_{2}$ and $v_{3}$. These
+surprising results have not yet been fully described by theoretical models. We
+will present the results obtained from real photons in the electromagnetic
+calorimeter and photons converted on the outer shell of the Hadron Blind
+Detector. PHENIX has also developed a new technique to identify conversion
+photons without assuming the radius where the conversion happened. This method
+greatly increases the available statistics and reduces systematic
+uncertainties.",1708.08088v1
+2017-09-24,"Anisotropic cosmological reconstruction in $f(R,T)$ gravity","Anisotropic cosmological models are constructed in $f(R,T)$ gravity theory to
+investigate the dynamics of universe concerning the late time cosmic
+acceleration. Using a more general and simple approach, the effect of the
+coupling constant and anisotropy on the cosmic dynamics have been investigated.
+Cosmic anisotropy is found affect substantially the cosmic dynamics.",1709.10399v2
+2017-10-25,Flux tubes in $N_f=2+1$ QCD with external magnetic fields,"We study the behavior of the confining flux tube in $N_f=2+1$ QCD at the
+physical point, discretized with the stout smearing improved staggered quark
+action and the tree level Symanzik gauge action. We discuss how it depends on a
+uniform external magnetic field, showing how it displays anisotropies with
+respect to the magnetic field direction. Moreover, we compare the observed
+anisotropy pattern with that of the static quark-antiquark potential we
+obtained in our previous works.",1710.09215v1
+2017-11-15,Anisotropy of thermal dileptons,"The meaningful specific anisotropy in the angle distribution of leptons with
+respect to the three-momentum of pair is predicted as a feasibility signature
+of synchrotron-like mechanism resulting from the quarks interacting with a
+collective confining color field in the heavy ion collisions. The lepton pair
+production rate and the spectrum of pair invariant mass are presented for this
+new dilepton source that is apparently not taken into consideration in the
+available phenomenological estimates.",1711.05459v2
+2017-11-28,Massive gravity and the suppression of anisotropies and gravitational waves in a matter-dominated contracting universe,"We consider a modified gravity model with a massive graviton, but which
+nevertheless only propagates two gravitational degrees of freedom and which is
+free of ghosts. We show that non-singular bouncing cosmological background
+solutions can be generated. In addition, the mass term for the graviton
+prevents anisotropies from blowing up in the contracting phase and also
+suppresses the spectrum of gravitational waves compared to that of the scalar
+cosmological perturbations. This addresses two of the main problems of the
+matter bounce scenario.",1711.10472v1
+2017-11-30,"Does Anisotropic ""Inflation"" Produce a Small Statistical Anisotropy?","Anisotropic inflation is an interesting model with an U(1) gauge field and it
+predicts the statistical anisotropy of the curvature perturbation characterized
+by a parameter $g_*$. However, we find that the background gauge field does not
+follow the classical attractor solution due to the stochastic effect. We
+develop the stochastic formalism of a vector field and solve Langevin and
+Fokker-Planck equations. It is shown that this model is excluded by the CMB
+constraint $g_*\le 10^{-2}$ with a high probability about $99.999\%$.",1711.11539v1
+2018-02-06,Co/Ni multilayers for spintronics: high spin-polarization and tunable magnetic anisotropy,"In this paper we analyze in details the electronic properties of (Co/Ni)
+multilayers, a model system for spintronics devices. We use magneto-optical
+Kerr (MOKE), spin-polarized photoemission spectroscopy (SRPES), x-ray magnetic
+circular dichroism (XMCD) and anomalous surface diffraction experiments to
+investigate the electronic properties and perpendicular magnetic anisotropy
+(PMA) in [Co(x)/Ni(y)] single-crystalline stacks grown by molecular beam
+epitaxy.",1802.02020v1
+2018-02-07,Virtual photon polarization and dilepton anisotropy in relativistic nucleus-nucleus collisions,"The polarization of virtual photons produced in relativistic nucleus-nucleus
+collisions provides information on the conditions in the emitting medium. In a
+hydrodynamic framework, the resulting angular anisotropy of the dilepton final
+state depends on the flow as well as on the transverse momentum and invariant
+mass of the photon. We illustrate these effects in dilepton production from
+quark-antiquark annihilation in the QGP phase and $\pi^+\pi^-$ annihilation in
+the hadronic phase for a static medium in global equilibrium and for a
+longitudinally expanding system.",1802.02479v2
+2018-03-05,Holographic Entanglement Entropy Decomposition in an Anisotropic Gauge Theory,"We study holographic entanglement entropy in spatially anisotropic field
+theory. We observe that for the background we consider in this paper, to a good
+approximation, the holographic entanglement entropy can be decomposed into two
+terms. One of them is the entanglement entropy of the isotropic field theory at
+fixed temperature and the other term is only a function of anisotropy
+parameter. Moreover, for large enough values of anisotropy parameter, our
+numerical results indicate that the entanglement entropy in the perpendicular
+direction to anisotropic direction is greater than the parallel case.",1803.01754v1
+2018-03-18,Effect of gap anisotropy on the spin resonance peak in the superconducting state of iron-based materials,"Spin resonance in the superconducting state of Fe-based materials within the
+multiorbital model with unequal anisotropic gaps on different Fermi surface
+sheets is studied. On the basis of the model gap function and the one
+calculated within the spin fluctuation theory of pairing, I show that the
+resonance peak shifts to higher frequencies with increasing the zero-amplitude
+gap magnitude. On the contrary, with increasing the gap anisotropy, it shifts
+to lower frequencies and lose some intensity.",1803.06736v2
+2018-03-22,Hyperbolic Blockade: Suppression of the Photonic Density of States and the Spontaneous Emission Rate at the Interface with Conducting Medium,"Surface scattering of free electrons strongly modifies the electromagnetic
+response near the interface. Due to the inherent anisotropy of the surface
+scattering that necessarily reverses the normal the interface component of the
+electron velocity while its tangential component may remain the same, a thin
+layer near a high-quality interface shows strong dielectric anisotropy. The
+formation of the resulting hyperbolic dispersion layers near the
+metal-dielectric interface strongly modifies the local density of states, and
+leads to orders of magnitude changes in all associated phenomena.",1803.08191v1
+2018-03-22,Engineering giant magnetic anisotropy in single-molecule magnets by dimerizing heavy transition-metal atoms,"Search for single-molecule magnets with large magnetic anisotropy energy
+(MAE) is essential for the development of molecular spintronics devices used at
+room temperature. Through systematic first-principles calculations, we found
+that an Os-Os or Ir-Ir dimer embedded in the (5,5'-Br2-Salophen) molecule gives
+rise to large MAE of 41.6 or 51.4 meV which is large enough to hold the spin
+orientation at room temperature. Analysis of electronic structures reveals that
+the top Os and Ir atoms are most responsible for the spin moments and large
+MAEs of the molecules.",1803.08213v1
+2018-05-07,Anisotropy of dark matter velocity distribution,"Direct detection of dark matter with directional sensitivity has the
+potential to discriminate the dark matter velocity distribution. Especially, it
+will be suitable to discriminate isotropic distribution from anisotropic one.
+Analyzing data produced with Monte-Carlo simulation, required conditions for
+the discrimination is estimated. If energy threshold of detector is optimized,
+$O(10^3-10^4)$ event number is required to discriminate the anisotropy.",1805.02472v1
+2018-07-15,"Anisotropy of Neel ""orange-peel"" coupling in magnetic multilayers","We calculate the energy of the magnetostatic interaction between two
+ferromagnetic films with uniform magnetization and correlated interfaces (the
+""orange-peel"" effect). The ""orange-peel"" coupling is anisotropic: the
+interaction is ferromagnetic when the films are magnetized in-plane; and it is
+antiferromagnetic when magnetization is out-of-plane. The interaction
+anisotropy can be used to distinguish the ""orange-peel"" effect from the
+interlayer exchange coupling.",1807.05590v1
+2018-09-27,Measurements of Fourier harmonics of azimuthal anisotropy in Pb+Pb and Xe+Xe collisions,"The high-statistics data sets collected by the LHC experiments during the
+heavy-ion runs allow for a detailed study of the azimuthal anisotropy of
+charged particles. This report presents the selected results of $v_{n}$
+measured in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV and Xe+Xe
+collisions at $\sqrt{s_\mathrm{NN}} = 5.44$ TeV, with emphasis on the higher
+order Fourier coefficients, $v_{n}$, sensitive to initial state fluctuations of
+the medium created in ultra-relativistic heavy-ion collisions.",1809.10648v2
+2018-10-03,Orbital-Flop Transition of Angular Momentum in a Topological Superfluid,"The direction of the orbital angular momentum of the $B$-phase of superfluid
+$^3$He can be controlled by engineering the anisotropy of the silica aerogel
+framework within which it is imbibed. In this work, we report our discovery of
+an unusual and abrupt `orbital-flop' transition of the superfluid angular
+momentum between orientations perpendicular and parallel to the anisotropy
+axis. The transition has no hysteresis, warming or cooling, as expected for a
+continuous thermodynamic transition, and is not the result of a competition
+between strain and magnetic field. This demonstrates the spontaneous
+reorientation of the order parameter of an unconventional BCS condensate.",1810.01901v1
+2018-10-17,Interface enhanced magnetic anisotropy in Pt/EuO films,"We report proximity effects of spin-orbit coupling in EuO$_{1-x}$ films
+capped with a Pt overlayer. Transport measurements suggest that current flows
+along a conducting channel at the interface between the Pt and EuO. The
+temperature dependence of the resistivity picks up the critical behaviors of
+EuO, i.e., the metal-to-insulator transition. We also find an unusual
+enhancement of the magnetic anisotropy in this structure from its bulk value
+which results from strong spin-orbit coupling across the Pt/EuO interface.",1810.07336v1
+2018-11-13,Confinement transition in a Kitaev-like honeycomb model with bond anisotropy,"The honeycomb $K-\Gamma$ model is known to have both deconfined spin liquid
+and confined phases. We study here a confinement transition between the Kitaev
+spin liquid and a dimerized phase in the limit of strong bond anisotropy. By
+partially projecting out Majorana states we are able to map the model onto a
+model of weakly coupled Ising chains in a transverse field. Within this mapping
+the ordered Ising phase corresponds to the condensation of $Z_2$ fluxes, or
+confinement. Our results may improve our understanding of the extensively
+studied spin liquid candidate material $\alpha$-RuCl$_3$, where $K-\Gamma$
+interactions are dominant.",1811.05499v1
+2018-11-19,Dilepton production and elliptic flow from an anisotropic quark-gluon plasma,"We calculate the yield and elliptic flow of mid-rapidity dileptons emitted
+from the quark-gluon plasma generated in Pb-Pb collisions at LHC. We use
+relativistic anisotropic hydrodynamics for the 3+1 dimensional evolution of the
+quark-gluon plasma and convolve this with the momentum-anisotropic local rest
+frame production rate for dileptons. The effects of momentum anisotropy of the
+quark distribution functions, viscosity to entropy density ratio, centrality of
+the collisions, and initial momentum anisotropy on the results are investigated
+and discussed.",1811.07486v2
+2018-11-26,Fluctuating shapes of the fireballs in heavy-ion collisions,"We argue that energy and momentum deposition from hard partons into
+quark-gluon plasma induces an important contribution to the final state hadron
+anisotropies. We also advocate a novel method of Event Shape Sorting which
+allow to analyse the azimuthal anisotropies of the fireball dynamics in more
+detail. A use of the method in femtoscopy is demonstrated.",1811.10349v1
+2018-12-06,Entanglement in anisotropic expanding spacetime,"We study the effect of space anisotropy in the entanglement generated by
+expanding universe on spin 0 and 1/2 fields. For massive scalar field we find
+revivals of entanglement entropy vs momentum after decreasing from the maximum
+at k = 0. In massive Dirac field the effect is a slight distortion of the
+non-monotonic profile giving rise to the maximum of entanglement entropy at k >
+0. More interestingly, massless field of both type can only get entangled
+through anisotropy, with a maximum of entanglement entropy occurring at k > 0.",1812.02835v1
+2018-12-14,The cubic Schr{ö}dinger regime of the Landau-Lifshitz equation with a strong easy-axis anisotropy,"We pursue our work on the asymptotic regimes of the Landau-Lifshitz equation
+for bi-axial ferromagnets. We put the focus on the cubic Schr{\""o}dinger
+equation, which is known to describe the dynamics in a regime of strong
+easy-axis anisotropy. In any dimension, we rigorously prove this claim for
+solutions with sufficient regularity. In this regime, we additionally classify
+the one-dimensional solitons of the Landau-Lifshitz equation and quantify their
+convergence towards the solitons of the one-dimensional cubic Schr{\""o}dinger
+equation.",1812.05854v1
+2019-01-17,$\mathbb{B}_0$-Valued Monogenic Functions to the theory of Plane Anisotropy,"A solution of the elliptic type PDE of the 4th order, being a reduction of
+the Eqs. of stress function corresponding to any case of plane anisotropy which
+is not equal to isotropy (proved by S.\,G.~Mikhlin), is described in terms of
+hypercomplex `analytic' functions with values in two-dimensional semisimple
+algebra over the field of complex numbers in case when a domain under
+consideration is bounded and simply-connected. A boundary value problem on
+finding a function which satisfies this PDE in the considered domain (bounded
+and simply-connected) and permits continuations (to the boundary) of operators
+$\frac{\partial}{\partial x}$ and $\frac{\partial}{\partial y}$ acted to it, is
+reduced to certain BVP for these hypercomplex functions.",1901.05882v1
+2019-01-23,Cracking and Stability of Non-Rotating Relativistic Spheres with Anisotropic Internal Stresses,"The stability of static uncharged spheres with anisotropic internal stresses
+is studied in general relativity. It has been noticed that pressure anisotropy
+plays an important role for stability of stellar structure. It is shown that
+radial profile of the stress anisotropy can be considered to decide potentially
+stable/unstable regions. Finally, pontentially stable/unstable regions of two
+known models of relativistic star have been examined.",1901.09808v2
+2019-03-01,Recent results from the Pierre Auger Observatory,"In this paper some recent results from the Pierre Auger Collaboration are
+presented. These are the measurement of the energy spectrum of cosmic rays over
+a wide range of energies ($10^{17.5}$ to above $10^{20}$ eV), studies of the
+cosmic-ray mass composition with the fluorescence and surface detector of the
+Observatory, the observation of a large-scale anisotropy in the arrival
+direction of cosmic rays above 8 x $10^{18}$ eV and indications of anisotropy
+at intermediate angular scales above 4 x $10^{19}$ eV. The astrophysical
+implications of the spectrum and composition results are also discussed.
+Finally the progress of the upgrade of the Observatory, AugerPrime is
+presented.",1903.00529v1
+2019-03-08,Anisotropy and controllable band structure in supra-wavelength polaritonic metasurfaces,"In this letter we exploit the extended coherence length of mixed
+plasmon/exciton states to generate active metasurfaces. For this purpose,
+periodic stripes of organic dye are deposited on a continuous silver film.
+Typical metasurface effects, such as effective behavior and geometry
+sensitivity, are measured for periods exceeding the polaritonic wavelength by
+more than one order of magnitude. By adjusting the metasurface geometry,
+anisotropy, modified band structure and unidimensional polaritons are
+computationally simulated and experimentally observed in reflectometry as well
+as in emission.",1903.03328v1
+2019-04-13,Reversible electric-field-driven magnetization in a columnar nanocomposite film,"Magnetic hysteresis loops show a moderate perpendicular anisotropy of the
+magnetostrictive CFO pillars, which is related to their vertical compression.
+The application of an electric field to the electromechanical PMN-PT substrate
+produced significant and reversible changes in the magnetization due to an
+additional strain-induced magnetic anisotropy. This demonstrates completely
+reversible, room-temperature electric-field-assisted control of magnetization
+in self-assembled vertical nanocomposites of CFO and BFO.",1904.06568v1
+2019-05-16,The Effect of Anisotropy on Holographic Entanglement Entropy and Mutual Information,"We study the effect of anisotropy on holographic entanglement entropy (HEE)
+and holographic mutual information (MI) in the Q-lattice model, by exploring
+the HEE and MI for infinite strips along arbitrary directions. We find that the
+lattice always enhances the HEE. The MI, however, is enhanced by lattice for
+large sub-regions; while for small sub-regions, the MI is suppressed by the
+lattice. We also discuss how these phenomena result from the deformation of
+geometry caused by Q-lattices.",1905.06808v2
+2019-06-04,Deterministic magnetization switching by voltage-control of magnetic anisotropy and Dzyaloshinskii-Moriya interaction under in-plane magnetic field,"Based on the micromagnetic simulations the magnetization switching in a
+triangle magnetic element by voltage-control of magnetic anisotropy and
+Dzyaloshinskii-Moriya interaction under in-plane magnetic field is proposed.
+The proposed switching scheme is not the toggle switching but the deterministic
+switching where the magnetic state is determined by the polarity of the applied
+voltage pulse. The mechanism and conditions for the switching are clarified.
+The results provide a fast and low-power writing method for magnetoresistive
+random access memories.",1906.01254v1
+2019-06-10,"Linking dissipation, anisotropy and intermittency in rotating stratified turbulence","Analyzing a large data base of high-resolution three-dimensional direct
+numerical simulations of decaying rotating stratified flows, we show that
+anomalous mixing and dissipation, marked anisotropy, and strong intermittency
+are all observed simultaneously in an intermediate regime of parameters in
+which both waves and eddies interact nonlinearly. A critical behavior governed
+by the stratification occurs at Richardson numbers of order unity, and with the
+flow close to being in a state of instability. This confirms the central
+dynamical role, in rotating stratified turbulence, of large-scale
+intermittency, which occurs in the vertical velocity and temperature
+fluctuations, as an adjustment mechanism of the energy transfer in the presence
+of strong waves.",1906.04302v2
+2019-06-19,Anisotropic Tolman VII solution by gravitational decoupling,"Using the gravitational decoupling by the minimal geometric deformation
+approach, we build an anisotropic version of the well-known Tolman VII
+solution, determining an exact and physically acceptable interior two-fluid
+solution that can represent behavior of compact objects. Comparison of the
+effective density and density of the perfect fluid is demonstrated explicitly.
+We show that the radial and tangential pressure are different in magnitude
+giving thus the anisotropy of the modified Tolman VII solution. The dependence
+of the anisotropy on the coupling constant is also shown.",1906.08368v1
+2019-06-28,Fine-tuning of orbital angular momentum in an optical parametric oscillator,"We investigate the dynamical properties of a type-II optical parametric
+oscillator pumped by a structured light beam carrying orbital angular momentum.
+Different dynamical regimes are theoretically derived and experimentally
+demonstrated, depending on the anisotropy effects imposed by the nonlinear
+medium. In a weakly anisotropic regime, fine-tuning of the orbital angular
+momentum transfer is obtained by adjusting the crystal parameters. Under strong
+anisotropy, orbital angular momentum transfer is not possible and a sharp
+dynamical behavior is observed, with abrupt switching between different
+transverse modes.",1907.00026v1
+2019-07-06,Angle-resolved broadband ferromagnetic resonance apparatus enabled through a spring-loaded sample mounting manipulator,"Broadband ferromagnetic resonance is a useful technique to determine the
+magnetic anisotropy and study the magnetization dynamics of magnetic thin
+films. We report a spring-loaded sample loading manipulator for reliable sample
+mounting and rotation. The manipulator enables maximum signal, enhances system
+stability and is particularly useful for fully automated in-plane-field
+angle-resolved measurements. This angle-resolved broadband ferromagnetic
+resonance apparatus provides a viable method to study anisotropic damping and
+weak magnetic anisotropies, both vital for fundamental research and
+applications.",1907.03097v1
+2019-08-06,Position-space curved-sky anisotropy quadratic estimation,"This document supplements the release of the Planck 2018 CMB lensing
+pipeline, now made publicly available. It collects calculations relevant to
+curved-sky separable quadratic estimators in the spin-weight, position-space
+correlation function formalism, including analytic calculations of estimator
+responses and Gaussian noise biases between arbitrary pairs of quadratic
+estimators. It also contains the derivation of optimal, joint gradient and curl
+mode quadratic estimators for parametrized anisotropy of arbitrary spin.",1908.02016v1
+2019-09-02,Extreme anisotropy and gyrotropy of surface polaritons in Weyl semimetals,"Weyl semimetals possess unique electrodynamic properties due to a combination
+of strongly anisotropic and gyrotropic bulk conductivity, surface conductivity,
+and surface dipole layer. We explore the potential of popular tip-enhanced
+optical spectroscopy techniques for studies of bulk and surface topological
+electron states in these materials. Anomalous dispersion, extreme anisotropy,
+and the optical Hall effect for surface polaritons launched by a nanotip
+provides information about Weyl node position and separation in the Brillouin
+zone, the value of the Fermi momentum, and the matrix elements of the optical
+transitions involving both bulk and surface electron states.",1909.00861v1
+2019-09-19,Dark Matter Mass and Anisotropy in Directional Detector,"Velocity distribution of dark matter is supposed to be isotropic
+Maxwell-Boltzmann distribution in most cases, however, other distribution
+models including anisotropic one are suggested by simulations. Directional
+direct detection of dark matter is expected to be a hopeful way to discriminate
+isotropic distribution from anisotropic one. We investigate the possibility to
+obtain the anisotropy and WIMP mass by Monte-Carlo simulation supposing the
+directional detector.",1909.08861v1
+2019-11-22,Modeling anisotropic magnetized strange quark stars,"Compact objects have an intrinsic anisotropy due to the presence of strong
+magnetic fields that cause considerable modifications on the equations of state
+(EoS). In this work, we study the impact of this anisotropy in the size and
+shape of magnetized strange quark stars using an axially symmetric metric in
+spherical coordinates, the gamma-metric. The results are compared with those
+obtained with the standard Tolman-Oppenheimer-Volkoff (TOV) equations for the
+parallel and perpendicular pressures independently. Differences in the results
+are discussed.",1911.10224v1
+2020-01-22,Beyond classical anisotropy and a new look to relativistic stars: a gravitational decoupling approach,"In this article, we propose a physical condition to extend interior isotropic
+solutions to anisotropic domains by gravitational decoupling in the framework
+of the Minimal Geometric Deformation approach. In particular, it is found that
+by using an expression reminiscent of the classical anisotropy factor, we can
+close the decoupling system of equations and a new anisotropic solution can be
+found. As an example, we extend the well--known Tolman IV.",2001.07961v2
+2020-01-27,Bidirectional switching assisted by interlayer exchange coupling in asymmetric magnetic tunnel junctions,"We study the combined effects of spin transfer torque, voltage modulation of
+interlayer exchange coupling and magnetic anisotropy on the switching behavior
+of perpendicular magnetic tunnel junctions (p-MTJs). In asymmetric p-MTJs, a
+linear-in-voltage dependence of interlayer exchange coupling enables the
+effective perpendicular anisotropy barrier to be lowered for both voltage
+polarities. This mechanism is shown to reduce the critical switching current
+and effective activation energy. Finally, we analyze the possibility of having
+switching via interlayer exchange coupling only.",2001.10024v1
+2020-02-18,Polarization loss in reflecting coating,"In laser gravitational waves detectors optical loss restricts sensitivity. We
+discuss polarization scattering as one more possible mechanism of optical
+losses. Circulated inside interferometer light is polarized and after
+reflection its plane of polarization can turn a little due to reflecting
+coating of mirror can have slightly different refraction index along axes $x,\,
+y$ in plane of mirror surface (optical anisotropy). This anisotropy can be
+produced during manufacture of coating (elasto-optic effect). This orthogonal
+polarized light, enhanced in cavity, produces polarization optical loss.
+Polarization map of mirrors is very important and we propose to measure it.
+Polarization loss can be important in different precision optical experiments
+based on usage of polarized light, for example, in quantum speed meter.",2002.08271v1
+2020-03-12,Minimizing movements for forced anisotropic mean curvature flow of partitions with mobilities,"Under suitable assumptions on the family of anisotropies, we prove the
+existence of a weak global $\frac{1}{n+1}$-H\""older continuous in time mean
+curvature flow with mobilities of a bounded anisotropic partition in any
+dimension using the method of minimizing movements. The result is extended to
+the case when suitable driving forces are present. We improve the H\""older
+exponent to $\frac12$ in the case of partitions with the same anisotropy and
+the same mobility and provide a weak comparision result in this setting for a
+weak anisotropic mean curvature flow of a partition and an anisotropic mean
+curvature two-phase flow.",2003.05761v1
+2020-04-08,Role of anisotropy to the compensation in the Blume-Capel trilayered ferrimagnet,"The trilayered Blume-Capel ($S=1$) magnet with nearest neighbour intralayer
+ferromagnetic and nearest neighbour interlayer antiferromagnetic interaction is
+studied by Monte Carlo simulation. Depending on the relative interaction
+strength and the value of anisotropy the critical temperature (where all the
+sublattice magnetisations and consequently the total magnetisation vanishes)
+and the compensation temperature (where the total magnetisation vanishes for a
+special combination of nonzero sublattice magnetisations) are estimated. The
+comprehensive phase diagrams with lines of critical temperatures and
+compensation temperatures for different parameter values are drawn.",2004.03930v3
+2020-04-28,The effects of collisions on the generation and suppression of temperature anisotropies and the Weibel instability,"The expansion of plasma with non-parallel temperature and density gradients,
+and the generation of magnetic field via the Biermann battery is modeled using
+particle-in-cell simulations that include collisional effects via Monte Carlo
+methods. A scaling of the degree of collisionality shows that an anisotropy can
+be produced, and drive the Weibel instability, for gradient scales shorter than
+the mean free path. For larger collision rates, the Biermann battery dominates
+as the cause of magnetic field generation. When the most energetic particles
+remain collisionless, the Nernst effect causes the Biermann field to be dragged
+with the heat flux, piled up, and enhanced.",2004.13365v1
+2020-07-23,Mathematical modeling of glioma invasion: acid- and vasculature mediated go-or-grow dichotomy and the influence of tissue anisotropy,"Starting from kinetic transport equations and subcellular dynamics we deduce
+a multiscale model for glioma invasion relying on the go-or-grow dichotomy and
+the influence of vasculature, acidity, and brain tissue anisotropy. Numerical
+simulations are performed for this model with multiple taxis, in order to
+assess the solution behavior under several scenarios of taxis and growth for
+tumor and endothelial cells. An extension of the model to incorporate the
+macroscopic evolution of normal tissue and necrotic matter allows us to perform
+tumor grading.",2007.12204v1
+2020-07-28,Maximal Function Characterizations of Hardy Spaces on ${\mathbb{R}}^{n}$ with Pointwise Variable Anisotropy,"In 2011, Dekel et al. developed highly geometric Hardy spaces $H^p(\Theta)$,
+for the full range $0<p\leq 1$, which are constructed by continuous multi-level
+ellipsoid covers $\Theta$ of $\mathbb{R}^n$ with high anisotropy in the sense
+that the ellipsoids can change shape rapidly from point to point and from level
+to level. In this article, if the cover $\Theta$ is pointwise continuous, then
+the authors further obtain some real-variable characterizations of
+$H^p(\Theta)$ in terms of the radial, the non-tangential and the tangential
+maximal functions, which generalize the known results on the anisotropic Hardy
+spaces of Bownik.",2007.14211v2
+2020-09-07,Anomalous In-plane Magnetic Anisotropy in Strain-mediated Converse Magnetoelectric Coupling,"Magnetic axis rotation (MAR) in ferromagnetic (FM) layers is crucial for
+strain-mediated converse magnetoelectric coupling. Employing the density
+functional theory (DFT), we computationally study the magnetic anisotropy of
+selected deformed FM materials such as body-centered iron. The results show
+that the short axis is more energy-favorable at high in-plane strain difference
+than previously predicted phenomenologically. This anomalous trend and the
+complex energy behaviors at different strain conditions explain why
+spin-lattice dynamics (SLD) simulation does not produce in-plane MAR and imply
+couplings between different energy terms together with high order coefficient
+contributions.",2009.03045v2
+2020-09-08,Critical dynamics of non-conserved strongly anisotropic permutation symmetric three-vector model,"We explore, employing the renormalization-group theory, the critical scaling
+behavior of the permutation symmetric three-vector model that obeys
+non-conserving dynamics and has a relevant anisotropic perturbation which
+drives the system into a non-equilibrium steady state. We explicitly find the
+independent critical exponents with corrections up to two loops. They include
+the static exponents $\nu$ and $\eta$, the off equilibrium exponent
+$\widetilde{\eta}$, the dynamic exponent $z$ and the strong anisotropy exponent
+$\Delta$. We also express the other anisotropy exponents in terms of these.",2009.03965v1
+2020-10-20,Cosmic ray anisotropies from transient extragalactic sources,"We study the spectrum and anisotropies of ultrahigh energy cosmic ray
+transient sources, accounting for the effects of their propagation through the
+turbulent extragalactic magnetic fields. We consider either bursting sources or
+sources emitting since a given initial time. We analyse in detail the
+transition between the diffusive and the quasi-rectilinear regimes, describing
+some new features that could be present",2010.10629v2
+2020-12-13,Tunneling magnetoresistance in ensembles of ferromagnetic granules with exchange interaction and random easy axes of magnetic anisotropy,"We study the tunneling magnetoresistance in the ensembles of ferromagnetic
+granules with random easy axes of magnetic anisotropy taking into account the
+exchange interaction between granules. It is shown that due to the exchange
+interaction magnetoresistance is effectively decoupled from magnetization, i.e.
+the strongest negative magnetoresistance can be observed at the field where
+magnetization is almost saturated. Under some conditions, the sign of
+magnetoresistance can be reversed and tunneling magnetoresistance can become
+positive at certain magnetic fields. Our theory agrees with measurements of
+magnetoresistance in ensembles of Fe granules in SiCxNy matrix.",2012.07114v1
+2020-12-21,Chiral Bosonic Topological Insulator on the Honeycomb Lattice with Anisotropic Interactions,"We study hard-core bosons on the honeycomb lattice in the presence of
+anisotropic nearest-neighbor repulsive interactions. Using a quantum Monte
+Carlo (QMC) technique, we extract the phase diagram of the model in terms of
+the filling and the anisotropy. At half-filling we find a dimer insulator phase
+near maximum anisotropy that is characterized by a finite topological
+entanglement entropy $\ln(2)/2$, indicative of a fractional quantum Hall state
+for bosons. We identify the presence of edge states and derive a QMC-based
+method to extract and verify their chirality. Remarkably, this phase arises in
+the absence of magnetic flux and without explicit lattice frustration.",2012.11461v1
+2020-12-27,On volume-preserving crystalline mean curvature flow,"In this work we consider the global existence of volume-preserving
+crystalline curvature flow in a non-convex setting. We show that a natural
+geometric property, associated with reflection symmetries of the Wulff shape,
+is preserved with the flow. Using this geometric property, we address global
+existence and regularity of the flow for smooth anisotropies. For the
+non-smooth case we establish global existence results for the types of
+anisotropies known to be globally well-posed.",2012.13839v1
+2021-02-10,Weibel instability beyond bi-Maxwellian anisotropy,"The shape of the anisotropic velocity distribution function, beyond the realm
+of strict Maxwellians can play a significant role in determining the evolution
+of the Weibel instability dictating the dynamics of self-generated magnetic
+fields. For non-Maxwellian distribution functions, we show that the direction
+of the maximum growth rate wavevector changes with shape. We investigate
+different laser-plasma interaction model distributions which show that their
+Weibel generated magnetic fields may require closer scrutiny beyond the second
+moment (temperature) anisotropy ratio characterization.",2102.05499v3
+2021-02-15,From n-layer planar ordering to the monolayer homeotropic structure of confined hard rods: The effect of shape anisotropy and wall-to-wall separation,"Using the Parsons Lee theory we examined the effect of shape anisotropy and
+the wall to wall separation on the phase behavior of the hard parallelepiped
+rods with dimensions L, D, and D (L>D) in such narrow slitlike pores which only
+one homeotropic layer can form. The phase structures, including biaxiality,
+planar nematic layering transition as well as planar to homeotropic, were
+studied for some separations in the range 2.5D<H<10.0D for H-D<L<H.",2102.07853v1
+2021-02-26,Distinctive magnetic properties of CrI3 and CrBr3 monolayers caused by spin-orbit coupling,"After the discovery of magnetism in monolayer CrI3, the magnetic properties
+of different 2D materials from the chromium-trihalide family are intuitively
+assumed to be similar, yielding magnetic anisotropy from the spin-orbit
+coupling on halide ligands. Here we reveal significant differences between the
+CrI3 and CrBr3 magnetic monolayers in their magnetic anisotropy, resulting
+Curie temperature, hysteresis in external magnetic field, and evolution of
+magnetism with strain, all predominantly attributed to distinctly different
+interplay of atomic contributions to spin-orbit coupling in two materials.",2102.13325v1
+2021-04-29,Thickness Dependence of Magneto-transport Properties in Tungsten Ditelluride,"We investigate the electronic structure of tungsten ditelluride (WTe$_2$)
+flakes with different thicknesses in magneto-transport studies. The
+temperature-dependent resistance and magnetoresistance (MR) measurements both
+confirm the breaking of carrier balance induced by thickness reduction, which
+suppresses the `turn-on' behavior and large positive MR. The Shubnikov-de-Haas
+oscillation studies further confirm the thickness-dependent change of
+electronic structure of WTe$_2$ and reveal a possible temperature-sensitive
+electronic structure change. Finally, we report the thickness-dependent
+anisotropy of Fermi surface, which reveals that multi-layer WTe$_2$ is an
+electronic 3D material and the anisotropy decreases as thickness decreases.",2104.14464v1
+2021-06-03,Magnon spin transport around the compensation magnetic field in easy-plane antiferromagnetic insulators,"In this work, we theoretically study the magnon spin transport in easy-plane
+antiferromagnetic insulators in the presence of an in-plane magnetic field. By
+exactly calculating the magnon spectrum, we find the band splitting due to the
+magnetic anisotropy can be fully compensated by the external field at a
+particular strength, which makes its dynamics nearly equivalent to an easy-axis
+antiferromagnet. As a result, the intrinsic magnon spin Hall effect due to the
+dipole-dipole interaction, previously predicted in easy-axis antiferromagnets
+is activated in easy-plane antiferromagnets. The compensation feature also
+allows the field control of magnon spin lifetime and hence the spin diffusion
+length. The compensation feature is robust against the biaxial anisotropy.",2106.02178v1
+2021-06-12,Anisotropic generalization of Buchdahl bound for specific stellar models,"Anisotropy is one factor that appears to be significantly important in the
+studies of relativistic compact stars. In this paper, we make a generalization
+of the Buchdahl limit by incorporating an anisotropic effect for a selected
+class of exact solutions describing anisotropic stellar objects. In the
+isotropic case of a homogeneous distribution, we regain the Buchdahl limit
+$2M/R \leq 8/9$. Our investigation shows a direct link between the maximum
+allowed compactness and pressure anisotropy vi-a-vis geometry of the associated
+$3$-space.",2106.08156v1
+2021-08-30,Anisotropic Optical Properties of Hexagonal Boron Nitride Thin Films,"Few-layer flakes of hexagonal boron nitride were prepared by ultrasonication
+of bulk crystals and agglomerated to form thin films. The transmission and
+reflection spectra of the thin films were measured. The spectral dependences of
+the linear and circular polarization revealed a hidden anisotropy of the films
+over the whole sample area which could not be explained by the anisotropy of
+the chaotically-oriented individual particles. Statistical analysis of optical
+microscopy images showed a macroscopic particle density distribution with
+ordering corresponding to the optical axis observed in the polarization data.",2108.13267v1
+2021-09-05,Pearl vortices in anisotropic superconducting films,"The magnetic field of vortices in anisotropic superconducting films is
+considered in the framework of anisotropic London approach. It is found that at
+distances large relative to the core size, the magnetic field normal to the
+film surface may change sign.
+  We find that the magnetic field attenuates at large distances as $1/r^3$ as
+it does in isotropic films, but the anisotropy induces an angular dependence to
+the supercurrents which causes the sign of the field to change for anisotropy
+parameters $\gamma=\lambda_2/\lambda_1>\sqrt{2}$ in some parts of the $(x,y)$
+plane.",2109.01966v1
+2021-10-13,Signatures of electronic correlations and spin-susceptibility anisotropy in nuclear magnetic resonance,"We present a methodology for probing the details of electronic susceptibility
+through minimally-invasive nuclear magnetic resonance techniques. Specifically,
+we classify electron-mediated long-range interactions in an ensemble of nuclear
+spins by revealing their effect on simple spin echo experiments. We find that
+pulse strength and applied field orientation dependence of these spin echo
+measurements resolves the spatial extent and anisotropy of electronic spin
+susceptibility. This work provides an alternate explanation to NMR results in
+superconducting and magnetically-ordered systems. The methodology has direct
+applications for sensing and characterizing emergent electronic phases.",2110.06811v1
+2021-10-19,Recent results of $\text{D}^{0}$ mesons azimuthal anisotropy using the CMS detector,"In a relativistic heavy ion collision, heavy flavor (charm and bottom) quarks
+are mostly created via hard processes at the early stage of the collisions. We
+present the latest results of the azimuthal anisotropy coefficients
+$v_{\text{n}}$ for prompt and nonprompt $\text{D}^{0}$ mesons in PbPb, pPb, and
+pp collisions from the CMS experiment. The studies are about collectivity
+phenomena in smaller systems (pp and pPb collisions), searches for the effects
+of very strong electromagnetic fields created in the initial stages of
+ultrarelativistic PbPb collisions, and charm quark energy loss in the
+quark-gluon plasma.",2110.09878v1
+2021-10-27,Planar Hall effect in Cu intercalated PdTe$_2$,"We present the Planar Hall effect studies on the Cu intercalated type-II
+Dirac semimetal PdTe$_{2}$. The electrical resistivity exhibits a positive
+field dependence both in perpendicular and parallel field directions, causing
+non-zero anisotropy. The longitudinal magnetoresistance shows almost linear
+field dependence at low temperatures. A tilted prolate spheroid shaped orbits
+are observed in parametric plot between transverse and longitudinal
+resistivities. Our study suggest that for the type-II Dirac semimetal materials
+with positive longitudinal magnetoresistance, the origin of Planar Hall effect
+cannot be asserted with certainty to the topological or non-topological without
+taking into account the anisotropy of Fermi surface.",2110.14251v1
+2021-11-08,Azimuthal anisotropy measurement of multi-strange hadrons in Au+Au collision at $\sqrt{s_{NN}}$ = 27 and 54.4 GeV at STAR,"In these proceedings, we present the second order ($v_{2}$) and the third
+order ($v_{3}$) azimuthal anisotropy measurements of strange and multi-strange
+hadrons such as $K^{0}_{S}$, $\Lambda$, $\bar{\Lambda}$, $\phi$, $\Xi^{-}$,
+$\bar{\Xi}^{+}$, $\Omega^{-}$, $\bar{\Omega}^{+}$ in Au+Au collisions at
+$\sqrt{s_{NN}}$ = 27 and 54.4 GeV at STAR. The centrality dependence of $v_{2}$
+and $v_{3}$ as well as the number of constituent quark scaling (NCQ scaling)
+for all the particles mentioned above are discussed. The ratio of $v_{2}$ of
+$\phi$ mesons to that of $\bar{p}$ is presented at $\sqrt{s_{NN}}$ = 54.4 GeV
+which gives a hint of mass ordering violation at low $p_{T}$.",2111.04743v1
+2022-01-12,The Ellipsoidal Universe and the Hubble tension,"The Hubble tension resides in a statistically significant discrepancy between
+early time and late time determinations of the Hubble constant. We discuss the
+Hubble tension within the Ellipsoidal Universe cosmological model. We suggest
+that allowing small anisotropies in the large-scale spatial geometry could
+alleviate the tension. We, also, show that the discrepancy in the measurements
+of the Hubble constant is reduced to a statistically acceptable level if we
+assume sizeable cosmological anisotropies during the Dark Age. In addition, we
+argue that the Ellipsoidal Universe cosmological model should resolve the $S_8$
+tension.",2201.04548v4
+2022-02-09,Electron Beam Weibel Instability in the Collisionless Shock with Low Mach Number,"The electron beam Weibel instability in the electrostatic collisionless shock
+is studied via particle in cell simulation. When the non-relativistic incoming
+plasmas collide with cold dilute plasmas, an electrostatic shock forms near the
+interface. Following that, a filamentary out-of-plane magnetic field is formed
+as a result of the Weibel instability. It is demonstrated that the anisotropy
+of incoming hot electrons is insufficient to trigger the Weibel instability.
+And the Weibel instability is excited by cold electrons in dilute plasmas.
+After being accelerated to relativistic velocities by the shock electric field
+into the dense plasmas, electrons in the dilute plasma have considerable
+anisotropy and can trigger the Weibel instability",2202.04341v1
+2022-02-27,Dual function spin-wave logic gates based on electric field control magnetic anisotropy boundary,"Spin waves (SWs) have been considered a promising candidate for encoding
+information with lower power consumption. Here, we propose the dual function SW
+logic gates based on the electric field controlling the SW propagation in the
+Fe film of Fe/BaTiO3 heterostructure with the motion of magnetic anisotropy
+boundary (MAB). We show micromagnetic simulations to validate the AND-OR and
+NAND-NOR logic gates. Our research may find a path for simplifying integrated
+logic circuits using such dual function SW logic gates.",2202.13258v1
+2022-03-04,Effect of the field self-interaction of General Relativity on the Cosmic Microwave Background Anisotropies,"Field self-interactions are at the origin of the non-linearities inherent to
+General Relativity. We study their effects on the Cosmic Microwave Background
+anisotropies. We find that they can reduce or alleviate the need for dark
+matter and dark energy in the description of the Cosmic Microwave Background
+power spectrum.",2203.02350v2
+2022-04-30,Piezoelectric ferromagnetism in two dimensional FeCl$_2$,"We predict that monolayer FeCl$_2$ is a two-dimensional piezoelectric
+ferromagnet (PFM) with easy-axis magnetism and a Curie temperature of 260 K.
+Our ab-initio calculations combined with data mining reveal 2H-FeCl$_2$ as the
+only easy-axis 2D monolayer PFM, and that its magnetic anisotropy increases
+many-fold with moderate hole doping. We develop an analysis based on magnetic
+anisotropy energy densities that explain the magnetic and doping-dependent
+behavior of FeCl$_2$, as well as VSe$_2$ and CrI$_3$, and can enable the design
+of future 2D magnetically ordered materials.",2205.00300v1
+2022-05-06,Emergent anisotropy in magnetic metamaterials,"We demonstrate directional dependence of the self-modification of internal
+mesospin textures in magnetic metamaterials, arising from the coupling of the
+atomic- and mesoscopic length-scales. Dressing the mesospins in different
+directions enables the quantification of the degree of texture in the internal
+magnetization and its impact on the interaction energy of the mesospins. The
+emerging anisotropy is manifested in a directional dependence of the remanent
+magnetization with temperature.",2205.03134v1
+2022-05-14,Magnetization Plateau of the Distorted Diamond Spin Chain with Anisotropic Ferromagnetic Interaction,"The $S=1/2$ distorted diamond spin chain with the anisotropic ferromagnetic
+interaction is investigated using the numerical diagonalization and the level
+spectroscopy analysis. It is known that the system exhibits a plateau of the
+magnetization curve at the 1/3 of the saturation. The present study indicates
+that as the anisotropy is varied the quantum phase transition occurs between
+two different mechanisms of the 1/3 magnetization plateau. The phase diagram
+with respect to the anisotropy and the ferromagnetic coupling is also
+presented.",2205.07027v1
+2022-05-18,Anisotropy of Halo Main Sequence Turnoff Stars Measured with New MMT Radial Velocities and Gaia Proper Motions,"We measure the anisotropy of the Milky Way stellar halo traced by a dense
+sample of 18<r<21 mag F-type main sequence turnoff stars using Gaia eDR3 proper
+motions and new radial velocity measurements published here.",2205.09755v1
+2022-06-21,Phase transitions in anisotropic graphene,"We study the effect of anisotropy on phase transitions in graphene. We work
+with an low energy effective field theory which is strongly coupled, and solve
+a coupled set of Schwinger-Dyson equations. We show that the effect of
+anisotropy is to reduce the critical coupling.",2206.10111v1
+2022-07-11,Contribution to the theory of waves in multi-dimensional linear dispersive media,"The asymptotic solutions for linear waves generated by oscillating source of
+elliptic shape in the motionless media is constructed with the recently
+developed Reference Solution Approach (RSA). Pronounced anisotropy of the
+solutions is found for elongated sources both for amplitudes and phases of the
+resulting wave pattern. The classic Kelvin angles of the ship wave patterns
+determine specific directions of this anisotropy, thus, demonstrating the role
+of wave dispersion. The analytical results within the RSA are shown to agree
+remarkably well with exact solutions of the linear wave problem.",2207.04938v1
+2022-08-18,Giant thermoelectric power factor anisotropy in PtSb$_{1.4}$Sn$_{0.6}$,"We report giant anisotropy in thermoelectric power factor ($S^2\sigma$) of
+marcasite structure-type PtSb$_{1.4}$Sn$_{0.6}$. PtSb$_{1.4}$Sn$_{0.6}$,
+synthesized using ambient pressure flux growth method upon mixing Sb and Sn on
+the same atomic site, is a new phase different from both PtSb$_2$ and PtSn$_2$
+that crystallize in the cubic $Pa\bar{3}$ pyrite and $Fm\bar{3}m$ fluorite unit
+cell symmetry, respectively. Giant difference in $S^2\sigma$ for heat flow
+applied along different principal directions of the orthorhombic unit cell
+mostly stems from anisotropic Seebeck coefficients.",2208.08647v1
+2022-11-14,Studies of decoherence in strongly anisotropic spin triangles with toroidal or general non-collinear easy axes,"Magnetic molecules are investigated with respect to their usability as units
+in future quantum devices. In view of quantum computing, a necessary
+prerequisite is a long coherence time of superpositions of low-lying levels. In
+this article, we investigate by means of numerical simulations whether a
+toroidal structure of single-ion easy anisotropy axes is advantageous as often
+conjectured. Our results demonstrate that there is no general advantage of
+toroidal magnetic molecules, but that arrangements of tilted anisotropy axes
+perform best in many cases.",2211.07281v2
+2022-11-18,Temperature dependence of spin-model parameters in antiferromagnets,"The temperature dependence of mesoscopic spin-model parameters is derived in
+two-sublattice antiferromagnetically aligned systems based on Green's function
+theory. It is found that transversal spin correlations decrease the anisotropy
+terms while increasing the Heisenberg and Dzyaloshinsky--Moriya exchange
+interactions and the latter's contribution to the anisotropy. The obtained
+temperature dependences show quantitative agreement with the results for
+ferromagnets, and they also agree well with numerical atomistic simulations
+which treat the spin correlations without approximations. Possible applications
+of the results in multiscale modelling are discussed.",2211.10204v2
+2022-12-03,Bulk ReSe2: record high refractive index and biaxially anisotropic material for all-dielectric nanophotonics,"We show that bulk rhenium diselenide, ReSe2 is characterized by record high
+value of the refractive index exceeding 5 in near-infrared frequency range. We
+use back focal plane reflection spectroscopy to extract the components of the
+ReSe2 permittivity tensor and reveal its extreme biaxial anisotropy. We also
+demonstrate the good agreement between the experimental data and the
+predictions of the density functional theory. The combination of the large
+refractive index and giant optical anisotropy makes ReSe2 a perspective
+material for all-dielectric nanophotonics in the near-infrared frequency range.",2212.01501v2
+2022-12-24,Anisotropic acoustics in dipolar Fermi gases,"We consider plane wave modes in ultracold, but not quantum degenerate,
+dipolar Fermi gases in the hydrodynamic limit. Longitudinal waves present
+anisotropies in both the speed of sound and their damping, and experience a
+small, undulatory effect in their flow velocity. Two distinct types of shear
+waves appear, a ``familiar"" one, and another that is accompanied by nontrivial
+density and temperature modulations. We propose these shear modes as an
+experimental means to measure the viscosity coefficients, including their
+anisotropies.",2212.12659v1
+2022-12-29,Magnetically enhanced thin film coarsening by a magnetic XPFC model allowing to decouple magnetic anisotropy and magnetostriction,"External magnetic fields provide a macroscopic control mechanism to influence
+the microstructure of polycrystalline materials. We model the influence of
+strong magnetic fields on grain growth in thin films with a magnetic extended
+phase field crystal (XPFC) model. The magneto-structural effects are
+incorporated into the correlation function in reciprocal space. With this
+approach magnetic anisotropy, magnetostriction and mobility of grain boundary
+can be controlled and a variety of geometrical and topological properties
+consistent with experimental results can be determined.",2212.14416v1
+2023-01-10,Semi-Classical quantisation of 3-particles Toda lattice augmented; Application to the Mixmaster anisotropy Hamiltonian,"Usual approaches to quantisation of a 3-Toda lead to numerical calculations
+requiring many steps that can be time consuming to insure their reliability. In
+order to reduce as much as possible the numerical part of the EKB quantisation
+procedure, and then to ease numerical calculations, we propose a reformulation
+of the mathematical framework with more adapted variables. The resulting
+equations and procedure might be easily implemented in a short Mathematica
+code. This more explicit framework will be useful for studying quantum
+Toda-Bianchi IX models in quantum cosmology where the true Bianchi IX
+anisotropy Hamiltonian can be approximated by a 3-particle Toda system.",2301.03929v1
+2023-02-14,Anisotropy effects on the quantum transport of atomic matter waves,"We discuss effects of anisotropic scattering in transport properties of
+ultracold atoms in three-dimensional optical potentials. Within the realm of
+the first Born approximation, we calculate the self energy, the scattering mean
+free time, the scattering mean free path, and the anisotropy factor. The
+behavior of the diffusion constant as a function of the wavenumber is also
+examined in diffusive and weak localization regimes. We show that these
+quantities are affected by quantum corrections due to the interference caused
+by disorder. The dimensionless conductance is also evaluated using the scaling
+theory of localization. Our results are compared with previous theoretical and
+the experimental results.",2302.07367v1
+2023-03-08,Majorana Gap Formation in the Anisotropic Kitaev Model with Ordered Flux Configuration,"We study the Kitaev model with direction dependent interactions to
+investigate how the flux configuration and/or the anisotropy in the exchanges
+affect the Majorana excitations. Systematic numerical calculations demonstrate
+how the anisotropy of the exchange couplings and flux configuration make the
+Majorana excitation gapped. The induced gapped quantum spin liquid states are
+distinct from the gapped one realized in the large anisotropic limit. The
+nature of gapped states can be explained by the superlattice potential due to
+flux configuration.",2303.04295v1
+2023-03-21,Unique Itinerant Ferromagnetism in 4d-electron System Ca2RuO4,"We have studied the magnetic properties of pressure-induced ferromagnet
+Ca2RuO4 to reveal the uniqueness of the 4d-electron ferromagnetism in the
+quasi-two-dimensional conductor. The magnetic parameters have been estimated
+from the paramagnetic susceptibility and the magnetisation process under
+pressure up to 2 GPa. The parameters can well be interpreted on the basis of
+the self-consistent renormalization theory of spin fluctuation for 3D-itinerant
+ferromagnet. Nevertheless, the metallic Ca2RuO4 shows quite strong anisotropy
+not only in the conductivity but also in the magnetisation process. Such the
+strong anisotropy is rare for an itinerant ferromagnet and is a unique
+characteristic of the 4d electron system Ca2RuO4.",2303.11604v1
+2023-03-18,Some new models of anisotropic relativistic stars in linear and quadratic regime,"Taking local anisotropy into consideration, in this paper, some new
+analytical models of relativistic anisotropic charged quark stars in linear and
+quadratic regime have been developed. The Einstein-Maxwell field equations have
+been solved with a particular form of metric potential and electric field
+intensity. The plots generated show that physical variables such as metric
+potentials, radial pressure, energy density, charge density, anisotropy, radial
+speed sound are consistent with realistic stellar models. We obtained some
+models consistent with stellar objects as 4U 1538-52, Cyg X-2, OGLE-TR-122b and
+red dwarf Proxima Centauri.",2303.12161v1
+2023-06-07,Versatile Parametric Classes of Covariance Functions that Interlace Anisotropies and Hole Effects,"Covariance functions are a fundamental tool for modeling the dependence
+structure of spatial processes. This work investigates novel constructions for
+covariance functions that enable the integration of anisotropies and hole
+effects in complex and versatile ways, having the potential to provide more
+accurate representations of dependence structures arising with real-world data.
+We show that these constructions extend widely used covariance models,
+including the Mat\'ern, Cauchy, compactly-supported hypergeometric and cardinal
+sine models. We apply our results to a geophysical data set from a
+rock-carbonate aquifer and demonstrate that the proposed models yield more
+accurate predictions at unsampled locations compared to basic covariance
+models.",2306.04483v1
+2023-06-17,Polarized Photons from the Early Stages of Relativistic Heavy-Ion Collisions,"The polarization of real photons emitted from early-time heavy-ion collisions
+is calculated, concentrating on the contribution from bremsstrahlung and
+quark-antiquark annihilation processes at leading order in the strong coupling.
+The effect of an initial momentum space anisotropy of the parton distribution
+is evaluated using a model for the non-equilibrium scattering kernel for
+momentum broadening. The effect on the photon polarization is reported for
+different degrees of anisotropy. The real photons emitted early during
+in-medium interactions will be dominantly polarized along the beam axis.",2306.10307v1
+2023-07-28,Analysis of magneto-optical Kerr spectra of ferrimagnetic Mn$_4$N,"Simulations of magneto-optical Kerr effect in biaxially strained Mn$_4$N are
+performed using density functional theory and linear response theory. We
+consider three ferrimagnetic phases, two collinear and one noncollinear, which
+have been corroborated separately by earlier studies. The simulated spectra are
+compared to magneto-optical data available in recent literature. A collinear
+ferrimagnetic phase with a small saturation magentization, a large
+perpendicular anisotropy, and Curie temperature above 700~K is found to be
+consistent with the measured spectra. We hypothesise that an admixture of the
+noncollinear phase, which could explain the lower than predicted net moment and
+magnetic anisotropy observed experimentally, is also present.",2307.15246v1
+2023-11-15,"Ultralight vector dark matter, anisotropies and cosmological adiabatic modes","In this work we study the early-time behavior and the background evolution of
+ultra-light vector dark matter. We present a model for vector dark matter in an
+anisotropic Bianchi type I universe. Vector fields source anisotropies in the
+early universe characterized by a shear tensor which rapidly decays once the
+fields start oscillating, making them viable dark matter candidates. We present
+the set of equations needed to evolve scalar cosmological perturbations in the
+linear regime, both in Synchronous gauge and Newtonian gauge. We show that the
+shear tensor has to be taken into account in the calculation of adiabatic
+initial conditions.",2311.09373v1
+2023-12-11,Experimental verification of the inverse Anomalous spin Hall effect with perpendicular magnetic anisotropy Materials,"In this work, the spin pumping technique was employed to investigate the
+anomalous inverse spin Hall effect in BIG/NiO/Fe samples where
+BIG[(Bi,Tm)3(Fe,Ga)5O12] exhibits perpendicular magnetic anisotropy. Our
+results reveal an intriguing phenomenon: when the magnetizations of both
+ferromagnetic layers align perpendicularly, a distinct spin-to-charge current
+conversion mechanism occurs. This conversion is intricately linked to the
+magnetization of the converting layer, spin polarization, and the spin current
+orientation.",2312.06819v1
+2023-12-17,Thermal leptogenesis in anisotropic cosmology,"There is no evidence that the universe must have been homogeneous and
+isotropic before the big bang nucleosynthesis. The Bianchi type-I cosmology is
+the simplest homogeneous but anisotropic cosmology. In this work, we
+investigate thermal leptogenesis, as a baryogenesis scenario, in the Bianchi
+type-I cosmology. Our results show that for specific values of the anisotropy,
+the modified thermal leptogenesis generated more baryon asymmetry than the
+standard one. In this way, anisotropy can help to achieve low-scale
+leptogenesis.",2312.10677v1
+2023-12-18,On the consequences of Raychaudhuri equation in Kantowski-Sachs space-time,"The paper aims to study the geometry and physics of the Raychaudhuri equation
+(RE) in the background of a homogeneous and anisotropic space-time described by
+Kantowski-Sachs (KS) metric. Role of anisotropy/shear in the context of
+convergence and possible avoidance of singularity has been analyzed subject to
+a physically motivated constraint. Moreover, using a suitable transformation
+the first order RE has been converted to a second order differential equation
+analogous to a Harmonic Oscillator and criterion for convergence has been shown
+to be associated with the time varying frequency of the Oscillator. Finally,
+the paper points out a geometric and physical notion of anisotropy along with
+their corresponding behavior towards convergence.",2312.11134v1
+2023-12-19,Measurements of azimuthal anisotropies in $^{16}$O+$^{16}$O and $γ$+Au collisions from STAR,"In this proceeding, we present the first measurements of azimuthal
+anisotropies, $v_2$ and $v_3$, in $^{16}$O+$^{16}$O collisions at 200 GeV as a
+function of transverse momentum and multiplicity, by using two- and
+four-particle correlation methods. We compare our measurements with STAR
+measurements of $v_n$ in \dau and \heau collisions to provide insight into the
+impact of system symmetry on initial condition for small systems. We also
+investigate the ratio $v_2\{4\}/v_2\{2\}$ as a function of centrality, which is
+expected to be sensitive to nucleon-nucleon correlation in the $^{16}$O
+nucleus.",2312.12167v1
+2023-12-24,A Novel Field-Free SOT Magnetic Tunnel Junction With Local VCMA-Induced Switching,"By integrating the local voltage-controlled magnetic anisotropy (VCMA)
+effect, Dzyaloshinskii-Moriya interaction (DMI) effect, and spin-orbit torque
+(SOT) effect, we propose a novel device structure for field-free magnetic
+tunnel junction (MTJ). Micromagnetic simulation shows that the device utilizes
+the chiral symmetry breaking caused by the DMI effect to induce a non-collinear
+spin texture under the influence of SOT current. This, combined with the
+perpendicular magnetic anisotropy (PMA) gradient generated by the local VCMA
+effect, enables deterministic switching of the MTJ state without an external
+field. The impact of variations in DMI strength and PMA gradient on the
+magnetization dynamics is analyzed.",2312.15481v1
+2024-01-09,Modelling the elliptical instability of magnetic skyrmions,"Two recently developed methods of modelling chiral magnetic soliton
+elliptical instability are applied in two novel scenarios, the tilted
+ferromagnetic phase of chiral magnets dominated by easy-plane anisotropy and
+the general case of the chiral magnet with tilted applied field and arbitrary
+uniaxial anisotropy. In the former case, the analytical predictions are found
+to exactly match previous numerical results. In the latter case, instability of
+isolated chiral skyrmions has not yet been studied, although the predictions
+correspond interestingly to previous numerical investigation of the phase
+diagram.",2401.04569v1
+2024-01-21,Structure-property relationships for weak-ferromagnetic perovskites,"Despite several decades of active experimental and theoretical studies of
+rare-earth orthoferrites, the mechanism of the formation of specific magnetic,
+magnetoelastic, optical, and magneto-optical properties remains a subject of
+discussion. This paper provides an overview of simple theoretical model
+approaches to quantitatively describing the structure-property relationships,
+in particular, interplay between FeO$_6$ octahedral deformations/rotations and
+main magnetic and optic characteristics such as N\'{e}el temperature, overt and
+hidden canting of magnetic sublattices, magnetic and magnetoelastic anisotropy,
+optic and photoelastic anisotropy.",2401.11424v1
+2024-02-26,Small-Scale Anisotropies of Cosmic Rays from Turbulent Flow,"Within the classical convection--diffusion approximation, we show that the
+angular distribution of cosmic rays (CRs) in a highly turbulent flow may
+exhibit significant small-scale anisotropies. The CR intensity angular power
+spectrum $ C_\ell $ is then a direct reflection of interstellar turbulence,
+from which one expects $ C_\ell\propto\ell^{-\gamma -1} $ for $ \ell\gg 1 $,
+where $ \gamma $ is the power-law turbulence spectral index. Observations by
+IceCube and HAWC at TeV energies can be explained approximately with the
+Kolmogorov law $ \gamma =5/3 $ with a convection velocity dispersion of 20 km/s
+on the scale of 10 pc.",2402.16554v1
+2024-02-26,On the causal discontinuity of Morse spacetimes,"Morse spacetime is a model of singular Lorentzian manifold, built upon a
+Morse function which serves as a global time function outside its critical
+points. The Borde-Sorkin conjecture states that a Morse spacetime is causally
+continuous if and only if the index and coindex of critical points of the
+corresponding Morse function are both different from 1. The conjecture has
+recently been confirmed by Garcia Heveling for the case of small anisotropy and
+Euclidean background metric. Here, we provide a complementary counterexample: a
+four dimensional Morse spacetime whose critical point has index 2 and large
+enough anisotropy is causally discontinuous and thus the Borde-Sorkin
+conjecture does not hold. The proof features a low regularity causal structure
+and causal bubbling.",2402.16571v1
+2024-02-20,Effects of anisotropy in an anisotropic extension of $w$CDM model,"In this paper, we derive observational constraints on an anisotropic $w$CDM
+model from observational data including Baryonic Acoustic Oscillations (BAOs),
+Cosmic Chronometer (CC), Big Bang Nucleosynthesis (BBN), Pantheon Plus (PP)
+compilation of Type Ia supernovae, and SH0ES Cepheid host distance anchors. We
+find that anisotropy is of the order $10^{-13}$, and its presence in the $w$CDM
+model reduces $H_0$ tension by $\sim 2\sigma$ and $\sim 1\sigma$ in the
+analyses with BAO+CC+BBN+PP and BAO+CC+BBN+PPSH0ES data combinations,
+respectively. In both analyses, the quintessence form of dark energy is favored
+at 95\% CL.",2402.16885v1
+1994-06-28,The Nature versus Nurture of Anisotropies,"With the rapidly growing number of cosmic microwave background measurements
+on various scales, there is real hope that the number of acceptable models for
+structure formation will be limited to a very few in the near future. Yet any
+given model can always be saved by introducing and tuning extraneous free
+parameters. To better understand this question of ``nature versus nurture'' for
+temperature fluctuations, it is useful to know not only the general features of
+anisotropy predictions but also their causes. Extracting the physical content
+of our other works, we present here a {\it simple} account of cosmic microwave
+background anisotropies on all scales. In particular, we show that analytic
+approximations can trace the structure of the so-called ``Doppler peaks,''
+which arise due to the {\it adiabatic} oscillations in the photon-baryon fluid.
+We also show how the finite thickness of the last scattering surface and the
+Silk damping mechanism can be described in a unified way by photon diffusion.
+In order to present a specific example, we focus on comparing the primordial
+isocurvature baryon (PIB) model with the standard cold dark matter model (CDM).
+In particular, we explain why PIB generically predicts larger {\it
+non}-oscillatory anisotropies from the 1$^\circ$ to 10$^\circ$ scale which may
+already be in conflict with experiments.",9406071v1
+1994-07-28,Anisotropies in the Cosmic Microwave Background: An Analytic Approach,"We introduce a simple yet powerful {\it analytic} method which obtains the
+structure of cosmic microwave background anisotropies to better than 5-10\% in
+temperature fluctuations on {\it all} scales. It is applicable to {\it any}
+model in which the potential fluctuations at recombination are both linear and
+known. Moreover, it recovers and explains the presence of the ``Doppler peaks''
+at degree scales as {\it driven} acoustic oscillations of the photon-baryon
+fluid. We treat in detail such subtleties as the time dependence of the
+gravitational driving force, anisotropic stress from the neutrino quadrupole,
+and damping during the recombination process, again all from an analytic
+standpoint. We apply this formalism to the standard cold dark matter model to
+gain physical insight into the anisotropies, including the dependence of the
+peak locations and heights on cosmological parameters such as $\Omega_b$ and
+$h$, as well as model parameters such as the ionization history. Damping due to
+the finite thickness of the last scattering surface and photon diffusion are
+further more shown to be identical. In addition to being a powerful probe into
+the nature of anisotropies, this treatment can be used in place of the standard
+Boltzmann code where 5-10\% accuracy in temperature fluctuations is
+satisfactory and/or speed is essential. Equally importantly, it can be used as
+a portable standard by which numerical codes can be tested and compared.",9407093v1
+1994-12-31,Large-angle Polarization of the Cosmic Microwave Background Radiation and Reionization,"We discuss the effect of matter reionization on the large-angular-scale
+anisotropy and polarization of the cosmic microwave background radiation (CMBR)
+in the standard CDM model. We separate three cases in which the anisotropy is
+induced by pure scalar, pure tensor, and mixed metric perturbations
+respectively. It is found that, if reionization occurs early enough, the
+polarization can reach a detectable level of sequentially $6\%$, $9\%$, and
+$6.5\%$ of the anisotropy. In general, a higher degree of polarization implies
+a dominant contribution from the tensor mode or reionization at high redshift.
+Since early reionization will suppress small-scale CMBR anisotropies and
+polarizations significantly, measuring the polarization on few degree scales
+can be a direct probe of the reionization history of the early universe.",9412097v2
+1995-07-13,Perturbation growth and cosmic microwave background anisotropies in the string-like matter dominated universe,"It is well known that the $\Lambda$-term is a very good candidate for the
+smooth component of the universe since it resolves the so-called
+``$\Omega$-problem'' giving, at the same time, sufficiently large age of the
+universe. However, the constant $\Lambda$-term is not the only possibility.
+Some people consider the $\Lambda$-term varying in time according to the law
+$\Lambda\approx R^{-2}$. Moreover the global texture in a closed universe and
+the network of cosmic strings obeying the same law of variation ($\rho\approx
+R^{-2}$) seem to be good candidates as well. We call the ``exotic'' form of
+matter scaling according to this law -- string-like matter. In the paper we
+discuss perturbation growth and anisotropies of the CMB in the string-like
+dominated universe. One can show that the perturbations cannot grow in the
+curvature dominated universe. Since the energy density of the string-like
+matter scales with the expansion in the same way as the curvature term one
+asserts that the perturbations cannot grow in the string-like matter dominated
+universe either. We find this generally accepted statement not quite correct
+and one of the purposes of the paper is to clear up this point. The second
+purpose of the paper is to check whether the eventual existence of the
+string-like matter may have an impact on the large-angular-scale anisotropies
+of the CMB. We show that such exotic matter has no effect on the value of the
+anisotropy amplitude $\delta T/T(theta).$",9507049v1
+1997-02-19,CMB Anisotropies: Total Angular Momentum Method,"A total angular momentum representation simplifies the radiation transport
+problem for temperature and polarization anisotropy in the CMB. Scattering
+terms couple only the quadrupole moments of the distributions and each moment
+corresponds directly to the observable angular pattern on the sky. We develop
+and employ these techniques to study the general properties of anisotropy
+generation from scalar, vector and tensor perturbations to the metric and the
+matter, both in the cosmological fluids and from any seed perturbations (e.g.
+defects) that may be present. The simpler, more transparent form and derivation
+of the Boltzmann equations brings out the geometric and model-independent
+aspects of temperature and polarization anisotropy formation. Large angle
+scalar polarization provides a robust means to distinguish between isocurvature
+and adiabatic models for structure formation in principle. Vector modes have
+the unique property that the CMB polarization is dominated by magnetic type
+parity at small angles (a factor of 6 in power compared with 0 for the scalars
+and 8/13 for the tensors) and hence potentially distinguishable independent of
+the model for the seed. The tensor modes produce a different sign from the
+scalars and vectors for the temperature-polarization correlations at large
+angles. We explore conditions under which one perturbation type may dominate
+over the others including a detailed treatment of the photon-baryon fluid
+before recombination.",9702170v3
+1997-03-24,The Anisotropy of Low Prandtl Number Turbulent Convection,"A model for homogeneous anisotropic incompressible turbulence is proposed.
+The model generalizes the GISS model of homogeneous isotropic turbulence; the
+generalization involves the solution of the GISS equations along a set of
+integration paths in wavenumber (k-) space. In order to make the problem
+tractable, these integration paths (""cascade lines"") must be chosen in such a
+way that the behaviour of the energy spectral function along different cascade
+lines should be reasonably similar. In practice this is realized by defining
+the cascade lines as the streamlines of a cascade flow; in the simplest case
+the source of this flow may be identified with the source function of the
+turbulence. Owing to the different approximations involved, the resulting
+energy spectral function is not exact but is expected to give good
+approximative values for the bulk quantities characterising the turbulent
+medium, and for the measure of the anisotropy itself in particular.
+  The model is then applied to the case of low Prandtl number thermal
+convection. The energy spectral function and the bulk quantities characterizing
+the flow are derived for different values of the parameter $S=Ra \sigma$. The
+most important new finding is that unlike the anisotropy of the most unstable
+mode in linear stability analysis the anisotropy of the turbulence does not
+grow indefinitely with increasing S but it rather saturates to a relatively
+moderate finite asymptotic value.",9703155v1
+1997-04-17,The Spectrum of the CMB Anisotropy from the Combined COBE FIRAS and DMR Observations,"We analyze the Cosmic Microwave Background (CMB) anisotropy data from the
+independent COBE FIRAS and DMR observations. We extract the frequency spectrum
+of the FIRAS signal that has the spatial distribution seen by DMR and show that
+it is consistent with CMB temperature fluctuations in the radiation well into
+the Wien region of the spectrum. Conversely, we form a map of the Planckian
+component of the sky temperature from FIRAS and show that it correlates with
+the DMR anisotropy map. The rms fluctuations at angular scales of 7 degrees are
+48 \pm 14 uK for the FIRAS data compared with 35 \pm 2 uK for the DMR data and
+31 \pm 6 uK for the correlated combination (1 sigma uncertainties). The
+consistency of these data, from very different instruments with very different
+observing strategies, provide compelling support for the interpretation that
+the signal seen by DMR is, in fact, temperature anisotropy of cosmological
+origin. The data also limit rms fluctuations in the Compton y parameter,
+observable via the Sunyaev- Zel'dovich effect, to Delta_y < 3 x 10^{-6} (95%
+CL) on 7 degree angular scales.",9704176v1
+1997-05-07,Multi-component models for disk galaxies. I. Stellar rotation and anisotropy,"We present here a self-consistent, tridimensional model of a disc galaxy
+composed by a number of ellipsoidal distributions of matter having different
+flattening and density profile. The model is self-consistent and takes into
+account the observed luminosity distribution, the flattening profile and the
+stellar rotation- and velocity dispersion- curves. In this paper we considered
+the particular case of a disc galaxy composed by two spheroidal bodies: an
+exponential disc and a bulge following the r^{1/4} law. We studied the behavior
+of the stellar rotation- and velocity dispersion- profiles along the sequence
+of S0s and Spirals, identified by an increasing disc-to-bulge ratio. Inside
+every class, kinematic curves were produced by changing the relative
+concentration of the two components and the inclination of the galaxy with
+respect to the line of sight. The comparison with observational data requires
+only two scaling factors: the total mass of the galaxy, and the effective
+radius.
+  The model allows also to detect the presence of anisotropy in the velocity
+distribution. In the special case of S0s, we explored the sensitivity of the
+kinematics of the model by changing the anisotropy and the flattening of the
+bulge. For intermediate flattening (0.4<b/a<0.85) it is possible to distinguish
+a change of anisotropy of 15%.
+  To show a real case, the model has been applied to the photometric and
+kinematic data of NGC 5866. We plan to apply these models to a larger database
+of S0 galaxies in a future paper.",9705042v2
+1997-06-25,Bayesian Analysis of the Polarization of Distant Radio Sources: Limits on Cosmological Birefringence,"A recent study of the rotation of the plane of polarization of light from 160
+cosmological sources claims to find significant evidence for cosmological
+anisotropy. We point out methodological weaknesses of that study, and reanalyze
+the same data using Bayesian methods that overcome these problems. We find that
+the data always favor isotropic models for the distribution of observed
+polarizations over counterparts that have a cosmological anisotropy of the type
+advocated in the earlier study. Although anisotropic models are not completely
+ruled out, the data put strong lower limits on the length scale $\lambda$ (in
+units of the Hubble length) associated with the anisotropy; the lower limits of
+95% credible regions for $\lambda$ lie between 0.43 and 0.62 in all anisotropic
+models we studied, values several times larger than the best-fit value of
+$\lambda \approx 0.1$ found in the earlier study. The length scale is not
+constrained from above. The vast majority of sources in the data are at
+distances closer than 0.4 Hubble lengths (corresponding to a redshift of
+$\approx$0.8); the results are thus consistent with there being no significant
+anisotropy on the length scale probed by these data.",9706258v1
+1997-08-22,MAX 4 and MAX 5 CMB anisotropy measurement constraints on open and flat-Lambda CDM cosmogonies,"We account for experimental and observational uncertainties in likelihood
+analyses of cosmic microwave background (CMB) anisotropy data from the MAX 4
+and MAX 5 experiments. These analyses use CMB anisotropy spectra predicted in
+open and spatially-flat Lambda cold dark matter cosmogonies. Amongst the models
+considered, the combined MAX data set is most consistent with the CMB
+anisotropy shape in Omega_0 ~ 0.1-0.2 open models and less so with that in old
+(t_0 >~ 15 - 16 Gyr, i.e., low h), high baryon density (Omega_B >~ 0.0175/h^2),
+low density (Omega_0 ~ 0.2 - 0.4), flat-Lambda models. The MAX data alone do
+not rule out any of the models we consider at the 2-sigma level.
+  Model normalizations deduced from the combined MAX data are consistent with
+those drawn from the UCSB South Pole 1994 data, except for the flat bandpower
+model where MAX favours a higher normalization. The combined MAX data
+normalization for open models with Omega_0 ~ 0.1-0.2 is higher than the upper
+2-sigma value of the DMR normalization. The combined MAX data normalization for
+old (low h), high baryon density, low-density flat-Lambda models is below the
+lower 2-sigma value of the DMR normalization. Open models with Omega_0 ~
+0.4-0.5 are not far from the shape most favoured by the MAX data, and for these
+models the MAX and DMR normalizations overlap. The MAX and DMR normalizations
+also overlap for Omega_0 = 1 and some higher h, lower Omega_B, low-density
+flat-Lambda models.",9708202v1
+1998-04-29,1+3 Covariant Cosmic Microwave Background anisotropies I: Algebraic relations for mode and multipole representations,"This is the first of a series of papers extending a covariant and gauge
+invariant (CGI) treatment of kinetic theory in curved space-times to a
+treatment of Cosmic Background Radiation (CBR) temperature anisotropies arising
+from inhomogeneities in the early universe. This paper deals with algebraic
+issues, both generically and in the context of models linearised about RW
+geometries.
+  The approach represents radiation anisotropies by PSTF tensors. The Angular
+correlation functions for the mode coefficients are found in terms of these
+quantities, following the Wilson-Silk approach, but derived and dealt with in
+CGI form. The covariant multipole and mode-expanded angular correlation
+functions are related to the usual treatments in the literature. The CGI mode
+expansion is related to the coordinate approach by linking the Legendre
+functions to the PSTF representation, using a covariant addition theorem for
+the tensors to generate the Legendre Polynomial recursion relation.
+  This paper lays the foundation for further papers in the series, which use
+this formalism in a CGI approach to develop solutions of the Boltzmann and
+Liouville equations for the CBR before and after decoupling, thus providing a
+unified CGI derivation of the variety of approaches to CBR anisotropies in the
+current literature.",9804316v3
+1999-01-13,CMB in Open Inflation,"The possibility to have an infinite open inflationary universe inside a
+bubble of a finite size is one of the most interesting realizations extensively
+discussed in the literature. The original idea was based on the theory of
+tunneling and bubble formation in the theories of a single scalar field.
+However, for a long time we did not have any consistent models of this type, so
+it was impossible to compare predictions of such models with the observational
+data on the CMB anisotropy. The first semi-realistic model of this type was
+proposed only very recently, in hep-ph/9807493. Here we present the results of
+our investigation of the scalar and tensor perturbation spectra and the
+resulting CMB anisotropy in such models. In all models which we have studied
+there are no supercurvature perturbations. The spectrum of scalar CMB
+anisotropies has a minimum at small l and a plateau at l > O(10) for low
+Omega_0. Meanwhile tensor CMB anisotropies are peaked at l=2. Relative
+magnitude of the scalar CMB spectra versus tensor CMB spectra at small l
+depends on the parameters of the models.",9901135v2
+1999-03-09,"Modelling elliptical galaxies: phase-space constraints on two-component (gamma1,gamma2) models","In the context of the study of the properties of the mutual mass distribution
+of the bright and dark matter in elliptical galaxies, present a family of
+two-component, spherical, self-consistent galaxy models, where one density
+distribution follows a gamma_1 profile, and the other a gamma_2 profile
+[(gamma_1,gamma_2) models], with different total masses and ``core'' radii. A
+variable amount of Osipkov-Merritt (radial) orbital anisotropy is allowed in
+both components. For these models, I derive analytically the necessary and
+sufficient conditions that the model parameters must satisfy in order to
+correspond to a physical system. Moreover, the possibility of adding a black
+hole at the center of radially anisotropic gamma models is discussed,
+determining analytically a lower limit of the anisotropy radius as a function
+of gamma. The analytical phase-space distribution function for (1,0) models is
+presented, together with the solution of the Jeans equations and the quantities
+entering the scalar virial theorem. It is proved that a globally isotropic
+gamma=1 component is consistent for any mass and core radius of the
+superimposed gamma=0 model; on the contrary, only a maximum value of the core
+radius is allowed for the gamma=0 model when a gamma=1 density distribution is
+added. The combined effects of mass concentration and orbital anisotropy are
+investigated, and an interesting behavior of the distribution function of the
+anisotropic gamma=0 component is found: there exists a region in the parameter
+space where a sufficient amount of anisotropy results in a consistent model,
+while the structurally identical but isotropic model would be inconsistent.",9903123v1
+1999-03-23,Cosmic microwave background anisotropy from wiggly strings,"We investigate the effect of wiggly cosmic strings on the cosmic microwave
+background radiation anisotropy and matter power spectrum by modifying the
+string network model used by Albrecht et al.. We employ the wiggly equation of
+state for strings and the one-scale model for the cosmological evolution of
+certain network characteristics. For the same choice of simulation parameters
+we compare the results with and without including wiggliness in the model and
+find that wiggliness together with the accompanying low string velocities lead
+to a significant peak in the microwave background anisotropy and to an
+enhancement in the matter power spectrum. For the cosmologies we have
+investigated (standard CDM, and, CDM plus cosmological constant), and within
+the limitations of our modeling of the string network, the anisotropy is in
+reasonable agreement with current observations but the COBE normalized
+amplitude of density perturbations is lower than what the data suggests. In the
+case of a cosmological constant and CDM model, a bias factor of about 2 is
+required.",9903361v4
+1999-06-26,Line-of-Sight Anisotropies within X-ray Luminous Cluster Samples,"We present the results from two-point spatial correlation analyses on X-ray
+confirmed northern Abell clusters. The cluster samples are subsets of a
+volume-limited ROSAT All-Sky Survey study of 294 Abell clusters of which 240
+are X-ray luminous. We examined magnitude- and volume-complete samples for
+differences according to richness and X-ray luminosity. For R>=1 clusters, we
+find r_0 = 22h^-1Mpc and gamma = -1.7, which is consistent with previous
+analyses of visually selected clusters. We also find no indications of
+line-of-sight anisotropies. For R >= 0 clusters, we find r_0= 17.5h^-1Mpc which
+is considerably lower than recent determinations of r_0 for similar X-ray
+bright cluster samples (e.g. the XBACs and the RASS1 clusters). All of the R>=0
+X-ray confirmed samples, including the XBACs and RASS1 clusters, show
+line-of-sight anisotropies. Since X-ray emissions confirm a cluster's reality,
+we conclude that these anisotropies are not the result of spuriously selected
+clusters. We also examine the Abell clusters for the depedence of r_0 and gamma
+on X-ray luminosity, and find no evidence for r_0 to grow with increasing X-ray
+luminosity thresholds. This is contrary to similar L_x vs. r_0 analyses of the
+RASS1 and XBACs cluster samples. We describe selection effects within the
+flux-limited XBACs and RASS1 samples and suggest how they can affect both the
+size of r_0 and its dependence on L_x.",9906423v1
+1999-11-01,Polarization of Thermal Emission from Aligned Dust Grains Under an Anisotropic Radiation Field,"If aspherical dust grains are immersed in an anisotropic radiation field,
+their temperature depends on the cross-sections projected in the direction of
+the anisotropy.It was shown that the temperature difference produces polarized
+thermal emission even without alignment, if the observer looks at the grains
+from a direction different from the anisotropic radiation. When the dust grains
+are aligned, the anisotropy in the radiation makes various effects on the
+polarization of the thermal emission, depending on the relative angle between
+the anisotropy and alignment directions. If the both directions are parallel,
+the anisotropy produces a steep increase in the polarization degree at short
+wavelengths. If they are perpendicular, the polarization reversal occurs at a
+wavelength shorter than the emission peak. The effect of the anisotropic
+radiation will make a change of more than a few % in the polarization degree
+for short wavelengths and the effect must be taken into account in the
+interpretation of the polarization in the thermal emission. The anisotropy in
+the radiation field produces a strong spectral dependence of the polarization
+degree and position angle, which is not seen under isotropic radiation. The
+dependence changes with the grain shape to a detectable level and thus it will
+provide a new tool to investigate the shape of dust grains. This paper presents
+examples of numerical calculations of the effects and demonstrates the
+importance of anisotropic radiation field on the polarized thermal emission.",9910560v1
+1999-12-07,CMB Anisotropy in Compact Hyperbolic Universes I: Computing Correlation Functions,"CMB anisotropy measurements have brought the issue of global topology of the
+universe from the realm of theoretical possibility to within the grasp of
+observations. The global topology of the universe modifies the correlation
+properties of cosmic fields. In particular, strong correlations are predicted
+in CMB anisotropy patterns on the largest observable scales if the size of the
+Universe is comparable to the distance to the CMB last scattering surface. We
+describe in detail our completely general scheme using a regularized method of
+images for calculating such correlation functions in models with nontrivial
+topology, and apply it to the computationally challenging compact hyperbolic
+spaces. Our procedure directly sums over images within a specified radius,
+ideally many times the diameter of the space, effectively treats more distant
+images in a continuous approximation, and uses Cesaro resummation to further
+sharpen the results. At all levels of approximation the symmetries of the space
+are preserved in the correlation function. This new technique eliminates the
+need for the difficult task of spatial eigenmode decomposition on these spaces.
+Although the eigenspectrum can be obtained by this method if desired, at a
+given level of approximation the correlation functions are more accurately
+determined. We use the 3-torus example to demonstrate that the method works
+very well. We apply it to power spectrum as well as correlation function
+evaluations in a number of compact hyperbolic (CH) spaces. Application to the
+computation of CMB anisotropy correlations on CH spaces, and the observational
+constraints following from them, are given in a companion paper.",9912124v1
+2000-03-27,The Anisotropy of MHD Alfvénic Turbulence,"We perform direct 3-dimensional numerical simulations for magnetohydrodynamic
+(MHD) turbulence in a periodic box of size $2\pi$ threaded by strong uniform
+magnetic fields. We use a pseudo-spectral code with hyperviscosity and
+hyperdiffusivity to solve the incompressible MHD equations. We analyze the
+structure of the eddies as a function of scale. A straightforward calculation
+of anisotropy in wavevector space shows that the anisotropy is scale-{\it
+independent}. We discuss why this is {\it not} the true scaling law and how the
+curvature of large-scale magnetic fields affects the power spectrum and leads
+to the wrong conclusion. When we correct for this effect, we find that the
+anisotropy of eddies depends on their size: smaller eddies are more elongated
+than larger ones along {\it local} magnetic field lines. The results are
+consistent with the scaling law $\tilde{k}_{\parallel} \sim
+\tilde{k}_{\perp}^{2/3}$ proposed by Goldreich and Sridhar (1995, 1997). Here
+$\tilde{k}_{\|}$ (and $\tilde{k}_{\perp}$) are wavenumbers measured relative to
+the local magnetic field direction. However, we see some systematic deviations
+which may be a sign of limitations to the model, or our inability to fully
+resolve the inertial range of turbulence in our simulations.",0003403v2
+2000-09-04,Secondary CMB anisotropies from the kinetic SZ effect,"We present an analytic model, based on previous works which tackled the
+reionization history of the universe, which allows us to describe the
+generation of the secondary CMB anisotropies due to the kinetic SZ effect. We
+take into account the ""patchy pattern"" of reionization (HII bubbles), the
+cross-correlations of these ionized regions, the small-scale fluctuations of
+the matter density field and the contribution from collapsed objects. For an
+open universe, we find that the power-spectrum $l(l+1)C_l/(2\pi)$ exhibits a
+plateau of height $10^{-13}$ in the range $10^3 < l < 10^6$. We find that for
+large wavenumbers $l > 10^4$ the signal is dominated by the contribution from
+collapsed halos while for $l < 10^4$ it is governed by the large-scale
+correlations of HII bubbles. This implies that one cannot discriminate
+reionization by stars from a quasar-driven scenario since the size of ionized
+regions never dominates the behaviour of the anisotropies. Moreover, the
+secondary CMB anisotropies arise from a broad range of redshifts (7.5<z<10 for
+the IGM and 0<z<7 for galactic halos). The signal expected in our model might
+bias the cosmological parameter estimation from CMB experiments such as Planck
+and could be detected by future mm-wavelength interferometers (e.g., ALMA).",0009040v2
+2000-12-04,Mass profiles and anisotropies of early-type galaxies,"We discuss the problem of using stellar kinematics of early-type galaxies to
+constrain the galaxies' orbital anisotropies and radial mass profiles. We
+demonstrate that compressing a galaxy's light distribution along the line of
+sight produces approximately the same signature in the line-of-sight velocity
+profiles as radial anisotropy. In particular, fitting spherically symmetric
+dynamical models to apparently round, isotropic face-on flattened galaxies
+leads to a spurious bias towards radial orbits in the models, especially if the
+galaxy has a weak face-on stellar disk. Such face-on stellar disks could
+plausibly be the cause of the radial anisotropy found in spherical models of
+intermediate luminosity ellipticals such as NGC 2434, NGC 3379 and NGC 6703.
+  In the light of this result, we use simple dynamical models to constrain the
+outer mass profiles of a sample of 18 round, early-type galaxies. The galaxies
+follow a Tully-Fisher relation parallel to that for spiral galaxies, but
+fainter by at least 0.8 mag (I-band) for a given mass. The most luminous
+galaxies show clear evidence for the presence of a massive dark halo, but the
+case for dark haloes in fainter galaxies is more ambiguous. We discuss the
+observations that would be required to resolve this ambiguity.",0012071v1
+2000-12-06,A Preliminary Detection of Arcminute Scale Cosmic Microwave Background Anisotropy with the BIMA Array,"We have used the Berkeley-Illinois-Maryland-Association (BIMA) array
+outfitted with sensitive cm-wave receivers to expand our search for arcminute
+scale anisotropy of the Cosmic Microwave Background (CMB). The interferometer
+was placed in a compact configuration toobtain high brightness sensitivity on
+arcminute scales over its 6.6' FWHM field of view. The sensitivity of this
+experiment to flat band power peaks at a multipole of l=5530 which corresponds
+to an angular scale of ~2'. We present the analysis of a total of 470 hours of
+on-source integration time on eleven independent fields which were selected
+based on their low IR contrast and lack of bright radio sources. Applying a
+Bayesian analysis to the visibility data, we find CMB anisotropy flat band
+power Q_flat = 6.1(+2.8/-4.8) microKelvin at 68% confidence. The confidence of
+a non- zero signal is 76% and we find an upper limit of Q_flat < 12.4
+microKelvin at 95% confidence. We have supplemented our BIMA observations with
+concurrent observations at 4.8 GHz with the VLA to search for and remove point
+sources. We find the point sources make an insignificant contribution to the
+observed anisotropy.",0012151v2
+2001-11-14,Cosmic Background Anisotropy due to Neutrino Oscillations Revisited,"This paper has been withdrawn by the author due to a crucial error in several
+equations.",0111264v3
+2001-12-01,Archeops: A CMB anisotropy balloon experiment measuring a broad range of angular scales,"The Cosmic Microwave Background Radiation is the oldest photon radiation that
+can be observed, having been emitted when the Universe was about 300,000 year
+old. It is a blackbody at 2.73 K, and is almost perfectly isotropic, the
+anisotropies being about one part to 100,000. However, these anisotropies,
+detected by the COBE satellite in 1992, constrain the cosmological parameters
+such as the curvature of the Universe. Archeops is a balloon-borne experiment
+designed to map these anisotropies. The instrument is composed of a 1.5 m
+telescope and bolometers cooled at 85 mK to detect radiation between 150 and
+550 GHz. To lower parasitic signals, the instrument is borne by a stratospheric
+balloon during the arctic night. This instrument is also a preparation for the
+Planck satellite mission, as its design is similar to HFI. We discuss here the
+results of the first scientific flight from Esrange (near Kiruna, Sweden) to
+Russia on January 29th 2001, which led to a 22 % (sub)millimetre sky coverage
+unprecedented at this resolution. Here, we put some emphasis on interstellar
+dust foreground emission observations.",0112010v1
+2001-12-17,High precision cosmology,"I review the current status of cosmology as emerging from recent observations
+of cosmic microwave background anisotropies as well as from other sources of
+cosmological information.",0112394v1
+2002-01-24,Radial orbital anisotropy and the Fundamental Plane of elliptical galaxies,"The existence of the Fundamental Plane (FP) imposes strong constraints on the
+structure and dynamics of elliptical galaxies, and thus contains important
+information on the processes of their formation and evolution. Here we focus on
+the relations between the FP thinness and tilt and the amount of radial orbital
+anisotropy. By using N-body simulations of galaxy models characterized by
+observationally motivated density profiles, and also allowing for the presence
+of live, massive dark matter halos, we explore the impact of radial orbital
+anisotropy and instability on the FP properties. The numerical results confirm
+a previous semi--analytical finding: the requirement of stability matches
+almost exactly the thinness of the FP. In other words, galaxy models that are
+radially anisotropic enough to be found outside the observed FP (with their
+isotropic parent models lying on the FP) are unstable, and their end--products
+fall back on the FP itself. We also find that a systematic increase of radial
+orbit anisotropy with galaxy luminosity cannot explain by itself the whole tilt
+of the FP, becoming the galaxy models unstable at moderately high luminosities:
+at variance with the previous case their end--products are found well outside
+the FP itself (abridged).",0201402v1
+2002-05-16,Measuring CMB Polarization with ESA PLANCK SubMM-Wave Telescope,"We analyze the polarization properties of the tilted off-axis dual-reflector
+submillimeter-wave telescope on the ESA PLANCK Surveyor designed for measuring
+the temperature anisotropies and polarization characteristics of the cosmic
+microwave background.",0205262v1
+2002-05-20,Small-scale microwave background anisotropies due to tangled primordial magnetic fields,"An inhomogeneous cosmological magnetic field creates vortical perturbations
+that survive Silk damping on much smaller scales than compressional modes. This
+ensures that there is no sharp cut-off in anisotropy on arc-minute scales. As
+we had pointed out earlier, tangled magnetic fields, if they exist, will then
+be a potentially important contributor to small-angular scale CMBR
+anisotropies. Several ongoing and new experiments, are expected to probe the
+very small angular scales, corresponding to multipoles with l>1000. In view of
+this observational focus, we revisit the predicted signals due to primordial
+tangled magnetic fields, for different spectra and different cosmological
+parameters. We also identify a new regime, where the photon mean-free path
+exceeds the scale of the perturbation, which dominates the predicted signal at
+very high l. A scale-invariant spectrum of tangled fields which redshifts to a
+present value B_{0}=3\times 10^{-9} Gauss, produces temperature anisotropies at
+the 10 micro Kelvin level between l ~ 1000-3000. Larger signals result if the
+univese is lambda dominated, if the baryon density is larger, or if the
+spectral index of magnetic tangles is steeper, n > -3. The signal will also
+have non-Gaussian statistics. We predict the distinctive form of the increased
+power expected in the microwave background at high l in the presence of
+significant tangled magnetic fields. We may be on the verge of detecting or
+ruling out the presence of tangled magnetic fields which are strong enough to
+influence the formation of large-scale structure in the Universe.",0205312v1
+2002-12-30,Dark Energy: Is it Q or Lambda ?,"New observations of Cosmic Microwave Background Anisotropies, Supernovae
+luminosity distances and Galaxy Clustering are sharpening our knowledge about
+dark energy. Here we present the latest constraints.",0212566v1
+2003-01-29,Statistical Isotropy of CMB and Cosmic Topology,"The breakdown of statistical homogeneity and isotropy of cosmic perturbations
+is a generic feature of ultra large scale structure of the cosmos, in
+particular, of non trivial cosmic topology. The statistical isotropy (SI) of
+the Cosmic Microwave Background temperature fluctuations (CMB anisotropy) is
+sensitive to this breakdown on largest scales comparable to, and even beyond
+the cosmic horizon. We study a set of measures, $\kappa_\ell$ ($\ell=1,2,3,
+>...$) which for non-zero values indicate and quantify statistical isotropy
+violations in a CMB map. The main goal here is to interpret the $\kappa_\ell$
+spectrum and relate it to characteristic patterns in the correlation function
+of CMB anisotropy arising from cosmic topology. We numerically compute the
+predicted $\kappa_\ell$ spectrum for CMB anisotropy in flat torus universe
+models. The essential features are captured in the leading order approximation
+to the correlation function where $\kappa_\ell$ can be calculated analytically.
+The $\kappa_\ell$ spectrum is shown to reflect the number, importance and
+relative orientation of principal directions in the CMB correlation dictated by
+the shape of the Dirichlet domain (DD) of the compact space and its size
+relative to cosmic horizon. Hence, besides detecting cosmic topology,
+$\kappa_\ell$ can discriminate between different topology of the universe
+complementing ongoing search for cosmic topology in CMB anisotropy data.",0301590v2
+2003-05-19,3-point temperature anisotropies in WMAP: Limits on CMB non-Gaussianities and non-linearities,"We present a study of the 3-pt angular correlation function w_3= <delta_1
+delta_2 delta_3> of (adimensional) temperature anisotropies measured by the
+Wilkinson Microwave Anisotropy Probe (WMAP). Results can be normalized to the
+2-point function w_2 = <delta_1 delta_2> in terms of the hierarchical: q_3 ~
+w_3/w_2^2 or dimensionless: d_3 ~ w_2/w_2^{3/2}$ amplitudes. Strongly
+non-Gaussian models are generically expected to show d_3 > 1 or q_3 > 10^3 d_3.
+Unfortunately, this is comparable to the cosmic variance on large angular
+scales. For Gaussian primordial models, q_3 gives a direct measure of the
+non-linear corrections to temperature anisotropies in the sky: delta = delta_L
++ f_{NLT} (delta_L^2 - <delta_L^2>) with f_{NLT} = q_3/2 for the leading order
+term in w_2^2. We find good agreement with the Gaussian hypothesis d_3 ~ 0
+within the cosmic variance of LCDM simulations (with or without a low
+quadrupole). The strongest constraints on q_3 come from scales smaller than 1
+degree. We find q_3 =19 +/-141 for (pseudo) collapsed configurations and an
+average of q_3 = 336 +/-218 for non-collapsed triangles. The corresponding
+non-linear coupling parameter, f_{NL}, for curvature perturbations Phi, in the
+Sachs-Wolfe (SW) regime is: f_{NL}^{SW} = q_3/6, while on degree scales, the
+extra power in acoustic oscillations produces f_{NL} ~ q_3/30 in the LCM model.
+Errors are dominated by cosmic variance, but for the first time they begin to
+be small enough to constrain the leading order non-linear effects with coupling
+of order unity.",0305327v2
+2003-06-04,The effect of imperfect corrections of PSF anisotropy on cosmic shear measurements,"Current measurements of the weak lensing signal induced by large scale
+structure provide useful constraints on a range of cosmological parameters.
+However, the ultimate succes of this technique depends on the accuracy with
+which one can correct for the effect of the Point Spread Function (PSF). In
+this paper we examine the accuracy of the PSF anisotropy correction using
+images of fields with a large number of stars. The ellipticity correlation
+function of the residuals is studied to quantify the effect of imperfect
+corrections for PSF anisotropy on cosmic shear studies. These imperfections
+occur on the chip scale and consequently the systematic signal decreases
+rapidly with increasing angular scale. Separation of the signal into ``E''
+(curl-free) and ``B'' (curl) components can help to identify the presence of
+residual systematics, but in general, the amplitude of the ``B''-mode is
+different from that of the ``E''-mode. The study of fields with many stars can
+be beneficial in finding a proper description of the variation of PSF
+anisotropy, and consequently help to significantly improve the accuracy with
+which the cosmic shear signal can be measured. We show that with such an
+approach it is feasible that the accuracy of future cosmic shear studies is
+limited by the statistical noise introduced by the intrinsic shapes of the
+sources. In particular, the prospects for accurate measurements of the cosmic
+shear signal on scales larger than ~10 arcminutes are excellent.",0306097v1
+2003-06-25,"How reliable is the kinematical evidence for dark matter: the effects of non-sphericity, substructure and streaming motions","Using cosmological $N$-body simulations of dark matter haloes, we study the
+effects of non-sphericity, substructure and streaming motions in reproducing
+the structure and internal kinematics of clusters of galaxies from kinematical
+measurements. Fitting an NFW model to the 3D density profile, we determine the
+virial mass, concentration parameter and velocity anisotropy of the haloes, and
+then calculate the profiles of projected velocity moments, as they would be
+measured by a distant observer. Using these mock data, we apply a Jeans
+analysis for spherical objects to reproduce the line-of-sight velocity
+dispersion and kurtosis and fit the three parameters. We find that the
+line-of-sight velocity dispersion and kurtosis profiles of a given halo can
+vary considerably with the angle of view of the observer. We show that the
+virial mass, concentration parameter and velocity anisotropy of the haloes can
+be reproduced satisfactorily independently of the halo shape, although the
+virial mass tends to be underestimated, the concentration parameter
+overestimated, while the recovered anisotropy is typically more tangential than
+the true one. The mass, concentration and velocity anisotropy of haloes are
+recovered with better precision when their mean velocity profiles are near
+zero.",0306520v2
+2003-08-20,Correlations Between the WMAP and MAXIMA Cosmic Microwave Background Anisotropy Maps,"We cross-correlate the cosmic microwave background temperature anisotropy
+maps from the WMAP, MAXIMA-I, and MAXIMA-II experiments. We use the
+cross-spectrum, which is the spherical harmonic transform of the angular
+two-point correlation function, to quantify the correlation as a function of
+angular scale. We find that the three possible pairs of cross-spectra are in
+close agreement with each other and with the power spectra of the individual
+maps. The probability that there is no correlation between the maps is smaller
+than 1 * 10^(-8). We also calculate power spectra for maps made of differences
+between pairs of maps, and show that they are consistent with no signal. The
+results conclusively show that the three experiments not only display the same
+statistical properties of the CMB anisotropy, but also detect the same features
+wherever the observed sky areas overlap. We conclude that the contribution of
+systematic errors to these maps is negligible and that MAXIMA and WMAP have
+accurately mapped the cosmic microwave background anisotropy.",0308355v3
+2003-08-22,First Star Signature in Infrared Background Anisotropies,"(Abridged) Recent cosmic microwave background anisotropy results from the
+Wilkinson Microwave Anisotropy Probe suggest that the universe was reionized at
+a redshift around 20. Such an early reionization could arise through the
+ionizing radiation emitted by metal-free population III stars at redshifts of
+10 and higher. We discuss infrared background (IRB) surface brightness spatial
+fluctuations from such a generation of early star formation. We show that the
+spatial clustering of these stars at tens of arcminute scales generates a
+contribution to the angular power spectrum of the IRB anisotropies at the same
+angular scales. This excess can be potentially detected when resolved
+foreground galaxies out to a redshift of a few is removed from the clustering
+analysis. Additionally, assuming a population III stellar spectrum, we suggest
+that the clustering excess related to the first generation of stars can be
+separated from brightness fluctuations resulting from other foreground sources
+and galaxies using multifrequency observations in the wavelength range of ~ 1
+to 5 microns. In addition to removing the low-redshift galaxy population, the
+multifrequency data are essential to account for certain foreground
+contaminants such zodiacal light, which, if varying spatially over degree
+scales, can be a significant source of confusion for the proposed study. Using
+various instruments, we study the extent to which spatial fluctuations of the
+IRB can be studied in the near future.",0308407v2
+2003-09-15,MAXIMA: A Balloon-Borne Cosmic Microwave Background Anisotropy Experiment,"We describe the Millimeter wave Anisotropy eXperiment IMaging Array (MAXIMA),
+a balloon-borne experiment designed to measure the temperature anisotropy of
+the Cosmic Microwave Background (CMB) on angular scales of 10' to 5 degrees .
+MAXIMA mapped the CMB using 16 bolometric detectors in spectral bands centered
+at 150 GHz, 240 GHz, and 410 GHz, with 10' resolution at all frequencies. The
+combined receiver sensitivity to CMB anisotropy was ~40 microK/rt(sec).
+Systematic parasitic contributions were minimized by using four uncorrelated
+spatial modulations, thorough crosslinking, multiple independent CMB
+observations, heavily baffled optics, and strong spectral discrimination.
+Pointing reconstruction was accurate to 1', and absolute calibration was better
+than 4%. Two MAXIMA flights with more than 8.5 hours of CMB observations have
+mapped a total of 300 deg^2 of the sky in regions of negligible known
+foreground emission. MAXIMA results have been released in previous
+publications. MAXIMA maps, power spectra and correlation matrices are publicly
+available at http://cosmology.berkeley.edu/maxima",0309414v1
+2003-10-29,The Effect of Proton Temperature Anisotropy on the Solar Minimum Corona and Wind,"A semi-empirical, axisymmetric model of the solar minimum corona is developed
+by solving the equations for conservation of mass and momentum with prescribed
+anisotropic temperature distributions. In the high-latitude regions, the proton
+temperature anisotropy is strong and the associated mirror force plays an
+important role in driving the fast solar wind; the critical point where the
+outflow velocity equals the parallel sound speed is reached already at 1.5 Rsun
+from Sun center. The slow wind arises from a region with open field lines and
+weak anisotropy surrounding the equatorial streamer belt. The model parameters
+were chosen to reproduce the observed latitudinal extent of the equatorial
+streamer in the corona and at large distance from the Sun. We find that the
+magnetic cusp of the closed-field streamer core lies at about 1.95 Rsun. The
+transition from fast to slow wind is due to a decrease in temperature
+anisotropy combined with the non-monotonic behavior of the non-radial expansion
+factor in flow tubes that pass near the streamer cusp. In the slow wind, the
+plasma beta is of order unity and the critical point lies at about 5 Rsun, well
+beyond the magnetic cusp. The predicted outflow velocities are consistent with
+OVI Doppler dimming measurements from UVCS/SOHO. We also find good agreement
+with polarized brightness (pB) measurements from LASCO/SOHO and HI Ly-alpha
+images from UVCS/SOHO.",0310846v1
+2003-11-10,Anisotropy in the Distribution of Satellite Galaxy Orbits,"Nearby clusters such as Virgo and Coma possess galaxy distributions which
+tend to be aligned with the principal axis of the cluster itself. This has also
+been confirmed by a recent statistical analysis of some 300 Abell clusters
+where the effect has been linked to the dynamical state of the cluster.
+Moreover, the orbits of satellite galaxies in galactic systems like our own
+Milky Way also demonstrate a high degree of anisotropy - the so-called Holmberg
+effect, the origin of which has been the subject of debate for more than 30
+years. This study presents the analysis of cosmological simulations focusing on
+the orbits of satellite galaxies within dark matter halos. The apocentres of
+the orbits of these satellites are preferentially found within a cone of
+opening angle ~40 around the major axis of the host halo, in accordance with
+the observed anisotropy found in galaxy clusters. We do, however, note that a
+link to the dynamical age of the cluster is not well established as both our
+oldest dark matter halos do show a clear anisotropy signal. Further analysis
+connects this distribution to the infall pattern of satellites along the
+filaments: the orbits are determined rather by the environment of the host halo
+than some ""dynamical selection"" during their life within the host's virial
+radius.",0311202v1
+2003-11-26,Detection and discrimination of cosmological non-Gaussian signatures by multi-scale methods,"Recent Cosmic Microwave Background (CMB) observations indicate that the
+temperature anisotropies arise from quantum fluctuations in the inflationary
+scenario. In the simplest inflationary models, the distribution of CMB
+temperature fluctuations should be Gaussian. However, non-Gaussian signatures
+can be present. They might have different origins and thus different
+statistical and morphological characteristics.
+  In this context and motivated by recent and future CMB experiments, we search
+for, and discriminate between, different non-Gaussian signatures. We analyse
+simulated maps of three cosmological sources of temperature anisotropies:
+Gaussian distributed CMB anisotropies from inflation, temperature fluctuations
+from cosmic strings and anisotropies due to the kinetic Sunyaev-Zel'dovich (SZ)
+effect both showing a non-Gaussian character. We use different multi-scale
+methods, namely, wavelet, ridgelet and curvelet transforms. The sensitivity and
+the discriminating power of the methods is evaluated using simulated data sets.
+  We find that the bi-orthogonal wavelet transform is the most powerful for the
+detection of non-Gaussian signatures and that the curvelet and ridgelet
+transforms characterise quite precisely and exclusively the cosmic strings.
+They allow us thus to detect them in a mixture of CMB + SZ + cosmic strings. We
+show that not one method only should be applied to understand non-Gaussianity
+but rather a set of different robust and complementary methods should be used.",0311577v1
+2003-12-31,CMB Observational Techniques and Recent Results,"The Cosmic Microwave Background (CMB) consists of photons that were last
+created about 2 months after the Big Bang, and last scattered about 380,000
+years after the Big Bang. The spectrum of the CMB is very close to a blackbody
+at 2.725 K and upper limits on any deviations of the CMB from a blackbody place
+strong constraints on energy transfer between the CMB and matter at all
+redshifts less than 2,000,000. The CMB is very nearly isotropic, but a dipole
+anisotropy of +/-3.346(17) mK shows that the Solar System barycenter is moving
+at 368+/-2 km/sec relative to the observable Universe. The dipole corresponds
+to a spherical harmonic index l=1. The higher indices l geq 2 indicate
+intrinsic inhomogeneities in the Universe that existed at the time of last
+scattering. While the photons have traveled freely only since the time of last
+scattering, the inhomogeneities traced by the CMB photons have been in place
+since the inflationary epoch only 10^{-35} sec after the Big Bang. These
+intrinsic anisotropies are much smaller in amplitude than the dipole
+anisotropy, with Delta T leq 100 microK. Electron scattering of the anisotropic
+radiation field produces an anisotropic linear polarization in the CMB with
+amplitudes less than 5 microK. Detailed studies of the angular power spectrum
+of the temperature and linear polarization anisotropies have yielded precise
+values for many cosmological parameters. This paper will discuss the techniques
+necessary to measure signals that are 100 million times smaller than the
+emission from the instrument and briefly describe results from experiments up
+to WMAP.",0401001v1
+2004-01-20,Detecting Population III stars through observations of near-IR cosmic infrared background anisotropies,"Following the successful mapping of the last scattering surface by WMAP and
+balloon experiments, the epoch of the first stars, when Population III stars
+formed, is emerging as the next cosmological frontier. It is not clear what
+these stars' properties were, when they formed or how long their era lasted
+before leading to the stars and galaxies we see today. We show that these
+questions can be answered with the current and future measurements of the
+near-IR cosmic infrared background (CIB). Theoretical arguments suggest that
+Population III stars were very massive and short-lived stars that formed at
+$z\sim 10-20$ at rare peaks of the density field in the cold-dark-matter
+Universe. Because Population III stars probably formed individually in small
+mini-halos, they are not directly accessible to current telescopic studies. We
+show that these stars left a strong and measurable signature via their
+contribution to the CIB anisotropies for a wide range of their formation
+scenarios. The excess in the recently measured near-IR CIB anisotropies over
+that from normal galaxies can be explained by contribution from early
+Population III stars. These results imply that Population III were indeed very
+massive stars and their epoch started at $z\sim 20$ and lasted past $z\lsim
+13$. We show the importance of accurately measuring the CIB anisotropies
+produced by Population III with future space-based missions.",0401401v2
+2004-02-23,Imaging the first light: experimental challenges and future perspectives in the observation of the Cosmic Microwave Background Anisotropy,"Measurements of the cosmic microwave background (CMB) allow high precision
+observation of the Last Scattering Surface at redshift $z\sim$1100. After the
+success of the NASA satellite COBE, that in 1992 provided the first detection
+of the CMB anisotropy, results from many ground-based and balloon-borne
+experiments have showed a remarkable consistency between different results and
+provided quantitative estimates of fundamental cosmological properties. During
+2003 the team of the NASA WMAP satellite has released the first improved
+full-sky maps of the CMB since COBE, leading to a deeper insight into the
+origin and evolution of the Universe. The ESA satellite Planck, scheduled for
+launch in 2007, is designed to provide the ultimate measurement of the CMB
+temperature anisotropy over the full sky, with an accuracy that will be limited
+only by astrophysical foregrounds, and robust detection of polarisation
+anisotropy. In this paper we review the experimental challenges in high
+precision CMB experiments and discuss the future perspectives opened by second
+and third generation space missions like WMAP and Planck.",0402528v1
+2004-05-10,Cosmological Magnetic Fields vs. CMB,"I present a short review of the effects of a cosmological magnetic field on
+the CMB temperature and polarization anisotropies. Various possibilities for
+constraining the magnetic field amplitude are discussed.",0405184v1
+2005-04-07,The Kinetic Sunyaev-Zel'dovich Effect from Reionization,"During the epoch of reionization, local variations in the ionized fraction
+(patchiness) imprint arcminute-scale temperature anisotropies in the CMB
+through the kinetic Sunyaev-Zel'dovich (kSZ) effect. We employ an improved
+version of an analytic model of reionization devised in Furlanetto et al.(2004)
+to calculate the kSZ anisotropy from patchy reionization. This model uses
+extended Press-Schechter theory to determine the distribution and evolution of
+HII bubbles and produces qualitatively similar reionization histories to those
+seen in recent numerical simulations. We find that the angular power spectrum
+of the kSZ anisotropies depends strongly on the size distribution of the HII
+bubbles and on the duration of reionization. In addition, we show that upcoming
+measurements of the kSZ effect should be able to distinguish between several
+popular reionization scenarios. In particular, the amplitude of the patchy
+power spectrum for reionization scenarios in which the IGM is significantly
+ionized by Population III stars (or by mini-quasars/decaying particles) can be
+larger (or smaller) by over a factor of 3 than the amplitude in more
+traditional reionization histories (with temperature anisotropies that range
+between 0.5 and 3 micro-Kelvin at l = 5000). We highlight the differences in
+the kSZ signal between many possible reionization morphologies and discuss the
+constraints that future observations of the kSZ will place on this epoch.",0504189v2
+2005-04-13,An indirect limit on the amplitude of primordial Gravitational Wave Background from CMB-Galaxy Cross Correlation,"While large scale cosmic microwave background (CMB) anisotropies involve a
+combination of the scalar and tensor fluctuations, the scalar amplitude can be
+independently determined through the CMB-galaxy cross-correlation. Using
+recently measured cross-correlation amplitudes, arising from the
+cross-correlation between galaxies and the Integrated Sachs Wolfe effect in CMB
+anisotropies, we obtain a constraint r < 0.5 at 68% confidence level on the
+tensor-to-scalar fluctuation amplitude ratio. The data also allow us to exclude
+gravity waves at a level of a few percent, relative to the density field, in a
+low - Lambda dominated universe(Omega_Lambda~0.5). In future, joining
+cross-correlation ISW measurements, which captures cosmological parameter
+information, with independent determinations of the matter density and CMB
+anisotropy power spectrum, may constrain the tensor-to-scalar ratio to a level
+above 0.05. This value is the ultimate limit on tensor-to-scalar ratio from
+temperature anisotropy maps when all other cosmological parameters except for
+the tensor amplitude are known and the combination with CMB-galaxy correlation
+allows this limit to be reached easily by accounting for degeneracies in
+certain cosmological parameters.",0504290v2
+2005-05-08,Radio Emission from Anisotropic Electron Distributions,"The effect of pitch-angle anisotropy of fast electrons on generation of
+nonthermal radio emission is studied. Incoherent gyrosynchrotron radiation is
+shown to depend strongly on the anisotropy. In particular, the spectral index
+of gyrosynchrotron radiation increases up to a factor of 3-4 compared with the
+isotropic case. The degree of polarization (X-mode) increases for loss-cone
+distributions, while decreases for beam-like distributions. Ample evidence of
+the pitch-angle anisotropy effect on (1) spatial distribution of the radio
+brightness, (2) spatially resolved light curves of the intensity and
+polarization, (3) spectral hardness of microwave bursts, is found by exploring
+observations performed with Nobeyama Radioheliograph and Owens Valley Solar
+Array. Above some threshold in the angular gradient, the electron cyclotron
+maser instability (coherent gyrosynchrotron emission) can develop, provided
+that standard gyrosynchrotron emission is accompanied by a lower-frequency
+intense coherent emission. The coherent emission is studied in detail for a
+realistic distribution of fast electrons over the energy and pitch-angle. In
+agreement with observations of narrowband radio spikes, it is found that (1)
+hard (power-law) distributions over energy are preferable to produce the
+coherent emission, (2) the threshold of the instability corresponds to quite an
+anisotropic electron distribution, thus, the pitch-angle anisotropy derived
+from the properties of the continuum gyrosynchrotron radiation will not
+necessarily give rise to coherent emission (either enhanced isotropization
+implied by quasilnear saturation of the instability).",0505146v1
+2005-08-22,Observation of the Anisotropy of 10 TeV Primary Cosmic Ray Nuclei Flux with the Super-Kamiokande-I Detector,"The relative sidereal variation in the arrival direction of primary cosmic
+ray nuclei of median energy 10 TeV was measured using downward, through-going
+muons detected with the Super-Kamiokande-I detector. The projection of the
+anisotropy map onto the right ascension axis has a first harmonic amplitude of
+$(6.64 \pm 0.98 {stat.} \pm 0.55 {syst.}) \times 10^{-4}$ and a phase at
+maximum at $(33.2^\circ \pm 8.2^\circ {stat.} \pm 5.1^\circ {syst.})$ right
+ascension. A sky map in equatorial coordinates indicates an excess region in
+the constellation of Taurus and a deficit region toward Virgo. The excess
+region is centered at $(\alpha_T, \delta_T) = (75^\circ \pm 7^\circ, -5^\circ
+\pm 9^\circ)$ with a half opening angle $\chi_T = (39 \pm 7)^\circ$; the excess
+flux is ($0.104 \pm 0.020$)% above the isotropic expectation. The corresponding
+parameters for the deficit region are $(\alpha_V, \delta_V) = (205^\circ \pm
+7^\circ, 5^\circ \pm 10^\circ)$, $\chi_V = (54 \pm 7)^\circ$, and $(-0.094 \pm
+0.014)$%. The data do not allow us to rule out a pure dipole form for the
+anisotropy (allowed at 13% confidence level); they are better described by the
+excess and deficit cones described above. We explored the implications under
+the assumption that the true anisotropy is not distorted too much by the
+analysis filter so that it is well-described by the observed excess and deficit
+cones.",0508468v4
+2005-09-08,Nonlinear Evolution of Cosmic Magnetic Fields and Cosmic Microwave Background Anisotropies,"In this work we investigate the effects of the primordial magnetic fields on
+cosmic microwave background anisotropies (CMB). Based on cosmological
+magnetohydrodynamic (MHD) simulations we calculate the CMB anisotropy spectra
+and polarization induced by fluid fluctuations (Alfv\'en modes) generated by
+primordial magnetic fields. The strongest effect on the CMB spectra comes from
+the transition epoch from a turbulent regime to a viscous regime. The balance
+between magnetic and kinetic energy until the onset of the viscous regime
+provides a one to one relation between the comoving coherence length $L$ and
+the comoving magnetic field strength $B$, such as $L \sim 30 (B/10^{-9}{\rm
+G})^3 \rm pc$. The resulting CMB temperature and polarization anisotropies are
+somewhat different from the ones previously obtained by using linear
+perturbation theory. Our calculation gives a constraint on the magnetic field
+strength in the intermediate scale of CMB observations. Upper limits are set by
+WMAP and BOOMERANG results for comoving magnetic field strength of $B < 28 \rm
+nG$ with a comoving coherence length of $L > 0.7 \rm Mpc$ for the most extreme
+case, or $B < 30 \rm nG$ and $L> 0.8 \rm Mpc$ for the most conservative case.",0509220v2
+2005-11-02,Searching For Integrated Sachs-Wolfe Effect Beyond Temperature Anisotropies: CMB E-mode Polarization-Galaxy Cross Correlation,"The cross-correlation between cosmic microwave background (CMB) temperature
+anisotropies and the large scale structure (LSS) traced by the galaxy
+distribution, or sources at different wavelengths, is now well known. This
+correlation results from the integrated Sachs-Wolfe (ISW) effect in CMB
+anisotropies generated at late times due to the dark energy component of the
+Universe. In a reionized universe, the ISW quadrupole rescatters and
+contributes to the large-scale polarization signal. Thus, in principle, the
+large-scale polarization bump in the E-mode should also be correlated with the
+galaxy distribution. Unlike CMB temperature-LSS correlation that peaks for
+tracers at low redshifts this correlation peaks mostly at redshifts between 1
+and 3. Under certain conditions, mostly involving a low optical depth to
+reionization, if the Universe reionized at a redshift around 6, the cross
+polarization-source signal is marginally detectable, though challenging as it
+requires all-sky maps of the large scale structure at redshifts between 1 and
+3. If the Universe reionized at a redshift higher than 10, it is unlikely that
+this correlation will be detectable even with no instrumental noise all-sky
+maps. While our estimates do not guarantee a detection unknown physics related
+to the dark energy as well as still uncertain issues related to the large
+angular scale CMB and polarization anisotropies may motivate attempts to
+measure this correlation using upcoming CMB polarization E-mode maps.",0511054v2
+2006-02-09,Constraints on the Evolution of the Primordial Magnetic Field from the Small-Scale Cosmic Microwave Background Angular Anisotropy,"Recent observations of the cosmic microwave background (CMB) have extended
+the measured power spectrum to higher multipoles $l\gtrsim$1000, and there
+appears to be possible evidence for excess power on small angular scales. The
+primordial magnetic field (PMF) can strongly affect the CMB power spectrum and
+the formation of large scale structure. In this paper, we calculate the CMB
+temperature anisotropies generated by including a power-law magnetic field at
+the photon last-scattering surface (PLSS). We then deduce an upper limit on the
+PMF based on our theoretical analysis of the power excess on small angular
+scales. We have taken into account several important effects such as the
+modified matter sound speed in the presence of a magnetic field. An upper limit
+to the field strength of $|B_\lambda|\lesssim$ 4.7 nG at the present scale of 1
+Mpc is deduced. This is obtained by comparing the calculated theoretical result
+including the Sunyaev-Zeldovich (SZ) effect with recent observed data on the
+small-scale CMB anisotropies from the $Wilkinson Microwave Anisotropy Probe$
+(WMAP), the Cosmic Background Imager (CBI), and the Arcminute Cosmology
+Bolometer Array Receiver (ACBAR). We discuss several possible mechanisms for
+the generation and evolution of the PMF.",0602224v5
+2006-03-30,The velocity dispersion and mass profile of the Milky Way,"We re-analyse the velocity-dispersion profile sigma(r) at radii r>10 kpc in
+the Galactic stellar halo, recently derived by Battaglia et al. (2005), who
+concluded that, for constant velocity anisotropy of the tracers, these data
+rule out a flat circular-speed curve for the Milky Way. However, we demonstrate
+that if one makes the natural assumption that the tracer density is truncated
+at r_t >~ 160 kpc and falls off significantly more steeply than r^-3.5 at r >~
+80 kpc, then these data are consistent with a flat circular-speed curve and a
+constant velocity anisotropy comparable to that observed for halo stars in the
+Solar neighbourhood. We also consider a more detailed mass model with an
+exponential stellar disc and an extended non-isothermal dark-matter halo. In
+this two-component model, the Milky Way's virial radius and mass are r_vir =
+200 kpc and M_vir = 1.5 x 10^12 M_sun. Still assuming the tracers' velocity
+anisotropy to be constant (at beta=0.5) we again find good agreement with the
+observed sigma(r), so long as the tracer density is truncated near the virial
+radius. These data by themselves do not allow to differentiate between
+different dark-halo or total-mass models for the Milky Way, nor between
+different velocity-anisotropy profiles for the tracers.",0603825v1
+2006-04-07,Weak Lensing of the Cosmic Microwave Background by Foreground Gravitational Waves,"Weak lensing distortion of the background cosmic microwave background (CMB)
+temperature and polarization patterns by the foreground density fluctuations is
+well studied in the literature. We discuss the gravitational lensing
+modification to CMB anisotropies and polarization by a stochastic background of
+primordial gravitational waves between us and the last scattering surface.
+While density fluctuations perturb CMB photons via gradient-type deflections
+only, foreground gravitational waves distort CMB anisotropies via both
+gradient- and curl-type displacements. The latter is a rotation of background
+images, while the former is related to the lensing convergence. For a
+primordial background of inflationary gravitational waves, with an amplitude
+corresponding to a tensor-to-scalar ratio below the current upper limit of
+$\sim$ 0.3, the resulting modifications to the angular power spectra of CMB
+temperature anisotropy and polarization are below the cosmic variance limit. At
+tens of arcminute angular scales and below, these corrections, however, are
+above the level at which systematics must be controlled in all-sky anisotropy
+and polarization maps with no instrumental noise and other secondary and
+foreground signals.",0604179v5
+2006-07-25,Measuring Statistical Isotropy of CMB Anisotropy,"The statistical expectation values of the temperature fluctuations and
+polarization of cosmic microwave background (CMB) are assumed to be preserved
+under rotations of the sky. We investigate the statistical isotropy (SI) of the
+CMB maps recently measured by the Wilkinson Microwave Anisotropy Probe (WMAP)
+using the bipolar spherical harmonic formalism proposed in Hajian & Souradeep
+2003 for CMB temperature anisotropy and extended to CMB polarization in Basak,
+Hajian & Souradeep 2006. The Bipolar Power Spectrum (BiPS) had been measured
+for the full sky CMB anisotropy maps of the first year WMAP data and now for
+the recently released three years of WMAP data. We also introduce and measure
+directional sensitive reduced Bipolar coefficients on the three year WMAP ILC
+map. Consistent with our published results from first year WMAP data we have no
+evidence for violation of statistical isotropy on large angular scales.
+Preliminary analysis of the recently released first WMAP polarization maps,
+however, indicate significant violation of SI even when the foreground
+contaminated regions are masked out. Further work is required to confirm a
+possible cosmic origin and rule out the (more likely) origin in observational
+artifact such as foreground residuals at high galactic latitude.",0607577v1
+2006-10-09,"Primordial magnetic field constrained from CMB anisotropies,and its generation and evolution before, during and after the BBN","The primordial magnetic field (PMF) can strongly affect the cosmic microwave
+background (CMB) power spectrum and the formation of large scale structure. In
+this presentation, we calculate the CMB temperature anisotropies generated by
+including a power-law magnetic field at the photon last scattering surface
+(PLSS). We then deduce an upper limit on the primordial magnetic field based
+upon our theoretical analysis of the power excess on small angular scales. We
+have taken into account several important effects such as the modified matter
+sound speed in the presence of a magnetic field. An upper limit to the field
+strength of $|B_\lambda|\lesssim$ 4.7 nG at the present scale of 1 Mpc is
+deduced. This is obtained by comparing the calculated theoretical result
+including the Sunyaev-Zeldovich (SZ) effect with recent observed data on the
+small scale CMB anisotropies from the Wilkinson Microwave Anisotropy Probe
+(WMAP), the Cosmic Background Imager (CBI) and the Arcminute Cosmology
+Bolometer Array Receiver (ACBAR). We discuss several possible mechanisms for
+the generation and evolution of the PMF before, during and after the BBN.",0610234v1
+2006-11-15,On the Influence of Resonant Scattering on Cosmic Microwave Background Polarisation Anisotropies,"We implement the theory of resonant scattering in the context of Cosmic
+Microwave Background (CMB) polarisation anisotropies. We compute the changes in
+the E-mode polarisation (EE) and Temperature E-mode (TE) CMB power spectra
+introduced by the scattering on a resonant transition with a given optical
+depth $\tau_X$ and polarisation coefficient $E_1$. The latter parameter,
+accounting for how anisotropic the scattering is, depends on the exchange of
+angular momentum in the transition and enables, {\it a priori}, to distinguish
+among different possible resonances. We use this formalism in two different
+scenarios: cosmological recombination and cosmological reionisation. In the
+context of cosmological recombination, we compute predictions in frequency and
+multipole space for the change in the TE and EE power spectra introduced by
+scattering on the $H_{\alpha}$ and $P_{\alpha}$ lines of Hydrogen. This
+constitutes a fundamental test for the standard model of recombination, and the
+sensitivity it requires is comparable to that needed in measuring the
+primordial CMB B-mode polarisation component. In the context of reionisation,
+we study the scattering off metals and ions produced by the first stars, and
+find that polarisation anisotropies, apart from providing a consistency test
+for intensity measurements, give some insight on how reionisation evolved:
+since they keep memory of how anisotropic the line scattering is, they should
+be able to discern the OI 63.2$\mu$m transition from other possible transitions
+associated to OIII, NII, NIII, etc. The amplitude of these signals are,
+however, between 10 to 100 times below the (already challenging) level of CMB
+B-mode polarisation anisotropies.",0611497v1
+2006-12-01,Slow evolution of elliptical galaxies induced by dynamical friction III. Role of density concentration and pressure anisotropy,"In this paper we study the infall, by dynamical friction, of rigid
+""satellites"" taken in a variety of initial configurations and models. We thus
+measure how dynamical friction depends on the density concentration and on the
+pressure anisotropy of the host galaxy and, separately, the response of the
+galaxy during the process.
+  The investigation is carried out by using a numerical laboratory set up in
+previous papers of this series.
+  We find that the pressure anisotropy present in the host galaxy has little
+effect on dynamical friction. Instead, the shape of the galaxy density profile
+is very important. The classical idealized description appears to be applicable
+to galaxy models characterized by a small density gradient but not to
+concentrated models. In contrast to the behavior found in small density
+gradient models, the orbits of satellites captured in concentrated models are
+not circularized by dynamical friction.
+  The induced evolution in the host galaxy reflects the initial conditions
+adopted for the captured satellite. Satellites spiraling in on quasi-circular
+orbits tend to modify the pressure tensor of the host galaxy in the tangential
+direction and the galaxy shape from spherical to oblate, while satellites
+captured along quasi-radial orbits tend to induce pressure anisotropy in the
+radial direction and to generate a prolate shape. This result suggests that the
+shape of early-type galaxies may result from occasional mergers rather than
+being directly related to the effectiveness of the radial-orbit instability
+during the process of formation via collisionless collapse, as often argued in
+the past.",0612020v1
+2007-01-18,The haloes of merger remnants,"We perform collisionless N-body simulations of 1:1 galaxy mergers, using
+models which include a galaxy halo, disc and bulge, focusing on the behaviour
+of the halo component. The galaxy models are constructed without recourse to a
+Maxwellian approximation. We investigate the effect of varying the galaxies'
+orientation, their mutual orbit, and the initial velocity anisotropy or cusp
+strength of the haloes upon the remnant halo density profiles and shape, as
+well as on the kinematics. We observe that the halo density profile (determined
+as a spherical average, an approximation we find appropriate) is exceptionally
+robust in mergers, and that the velocity anisotropy of our remnant haloes is
+nearly independent of the orbits or initial anisotropy of the haloes. The
+remnants follow the halo anisotropy - local density slope (\beta-\gamma)
+relation suggested by Hansen & Moore (2006} in the inner parts of the halo, but
+\beta is systematically lower than this relation predicts in the outer parts.
+Remnant halo axis ratios are strongly dependent on the initial parameters of
+the haloes and on their orbits. We also find that the remnant haloes are
+significantly less spherical than those described in studies of simulations
+which include gas cooling.",0701541v2
+1995-11-27,Superconducting state properties of a d-wave superconductor with mass anisotropy,"YBa$_2$Cu$_3$O$_7$ (YBCO) exhibits a large anisotropy between the $a$ and $b$
+axes in the CuO$_2$ planes because of the presence of CuO chains. In order to
+account for such an anisotropy we develop a Ginzburg-Landau (GL) theory for an
+anisotropic d-wave superconductor in an external magnetic field, based on an
+anisotropic effective mass approximation within CuO$_2$ planes. The anisotropic
+parameter $\lambda=m_x/m_y$, where $m_x$ ($m_y$) is the effective mass in the
+$x$ ($y$) direction, is found to have significant physical consequences: In the
+bulk case, there exist both the $s$- and $d$-wave order parameters with the
+same transition temperature, as long as $\lambda\ne 1$. The GL equations are
+also solved both analytically and numerically for the vortex state, and it is
+shown that both the $s$- and $d$-wave components show a two-fold symmetry, in
+contrast to the four-fold symmetry around the vortex, as expected for the
+purely $d$-wave vortex. With the deviation of $\lambda$ from unity, the
+opposite winding between the $s$- and $d$-wave components observed in the
+purely $d$-wave case is gradually taken over by the same winding number. The
+vortex lattice is found to have oblique structure in a wide temperature range
+with the precise shape depending on the anisotropy.",9511130v1
+1997-04-15,Static and Dynamical Anisotropy Effects in Mixed State of D - Wave Superconductors,"We describe effects of anisotropy caused by the crystal lattice in d-wave
+superconductors with s-wave mixing using the effective free energy approach.
+Only the d-wave order parameter field $d$ is introduced, while the effect of
+the s wave mixing as well as other effects breaking the rotational symmetry
+down to the fourfold symmetry of the crystal are represented by a single four
+(covariant) derivative term: $\eta d^{*}(\Pi _{y}^{2}-\Pi_{x}^{2})^{2}d $. The
+single vortex solution in a phenomenologically interesting range of parameters
+is almost identical to the two order parameters approach. We analytically
+consider the most general oblique lattice and orientation, but find that only
+rectangular body centered lattices are realized. A critical value $\eta _{c} $
+at which a phase transition from the rectangular lattice to the square lattice
+takes place. The influence on the phase transition line is discussed. The
+formalism is extended to the time dependent anisotropic Ginzburg-Landau
+equations in order to calculate the effect of the anisotropy on the flux flow.
+The moving vortex structure is established and the magnetization as function of
+the current is calculated. Although the linear conductivity tensor is
+rotationally invariant due to the fourfold symmetry, the nonlinear one shows
+anisotropy. We calculate dependence of both direct and Hall I-V curves on the
+angle between the current and the crystal lattice orientation.",9704131v1
+2001-05-16,Angular dependence of the bulk nucleation field Hc2 of aligned MgB2 crystallites,"Studies on the new MgB2 superconductor, with a critical temperature Tc ~ 39
+K, have evidenced its potential for applications although intense magnetic
+relaxation effects limit the critical current density, Jc, at high magnetic
+fields. This means that effective pinning centers must be added into the
+material microstructure, in order to halt dissipative flux movements.
+Concerning the basic microscopic mechanism to explain the superconductivity in
+MgB2, several experimental and theoretical works have pointed to the relevance
+of a phonon-mediated interaction, in the framework of the BCS theory. Questions
+have been raised about the relevant phonon modes, and the gap and Fermi surface
+anisotropies, in an effort to interpret spectroscopic and thermal data that
+give values between 2.4 and 4.5 for the gap energy ratio. Preliminary results
+on the anisotropy of Hc2 have shown a ratio, between the in-plane and
+perpendicular directions, around 1.7 for aligned MgB2 crystallites and 1.8 for
+epitaxial thin films. Here we show a study on the angular dependence of Hc2
+pointing to a Fermi velocity anisotropy around 2.5. This anisotropy certainly
+implies the use of texturization techniques to optimize Jc in MgB2 wires and
+other polycrystalline components.",0105332v2
+2001-09-04,Magnetotransport of CeRhIn5,"We report measurements of the temperature-dependent anisotropic resistivity
+and in-plane magnetoresistance on single crystals of the tetragonal
+heavy-fermion antiferromagnet (TN = 3.8 K) CeRhIn5. The measurements are
+reported in the temperature range 1.4 K to 300 K and in magnetic fields to 18
+tesla. The resistivity is moderately anisotropic, with a room-temperature
+c-axis to in-plane resistivity ratio rho_c/rho_a(300 K) = 1.7. rho(T)
+measurements on the non-magnetic analog LaRhIn5 indicate that the anisotropy in
+the CeRhIn5 resistivity stems predominately from anisotropy in Kondo-derived
+magnetic scattering. In the magnetically ordered regime an applied field H
+reduces TN only slightly due to the small ordered moment (0.37mu_B) and
+magnetic anisotropy. The magnetoresistance (MR) below TN is positive and varies
+linearly with H. In the paramagnetic state a positive MR is present below 7.5
+K, while a high-field negative contribution is evident at higher temperatures.
+The positive contribution decreases in magnitude with increasing temperature.
+Above 40 K the positive contribution is no longer observable, and the MR is
+negative. The low-T positive MR results from interactions with the
+Kondo-coherent state, while the high-T negative MR stems from single-impurity
+effects. The H and T-dependent magnetotransport reflects the magnetic
+anisotropy and Kondo interactions at play in CeRhIn5.",0109062v1
+2002-05-02,Super-conducting critical fields and anisotropy of a MgB2 single crystal,"Despite the intense activity in the year since the discovery of
+superconductivity in MgB2, key parameters, in particular the upper and lower
+critical fields Hc2 and Hc1 and their anisotropies, are not well-established,
+largely because of the difficulty of growing MgB2 crystals. Attempts have been
+made to deduce these parameters from experiments on polycrystalline material,
+but they have substantial uncertainties. Hc2 is particularly important for
+applications, as it is the field which quenches bulk super-conductivity. In
+terms of understanding MgB2, it is now clear that the conventional
+electron-phonon interaction is strong enough to account for the high transition
+temperature Tc, but the consequences of the double super-conducting gap for the
+anisotropy and its dependence on temperature, are uncertain. Here we describe
+detailed direct measurements of Hc1(T) and Hc2(T) for the two principal
+crystallographic directions in a clean single crystal of MgB2. For fields in
+the c-direction, $\mu_0 H^c_{c1}(0)$ = $0.28 +- 0.01T$ and $\mu_0 H^c_{c2}(0)$
+is $3 +- 0.5T$; this ratio of critical fields is rather low and implies that
+MgB2 is only just a Type II super-conductor. The anisotropies of both critical
+fields are close to 2.",0205036v2
+2002-06-14,"Reply to Comment on ""Weak anisotropy and disorder dependence of the in-plane magnetoresistance in high mobility (100) Si-inversion layers""",Reply to the Comment by V.T. Dolgopolov and A.V. Gold [cond-mat/0203276].,0206279v1
+2002-09-06,The Transition State in Magnetization Reversal,"We consider a magnet with uniaxial anisotropy in an external magnetic field
+along the anisotropy direction, but with a field magnitude smaller than the
+coercive field. There are three representative magnetization configurations
+corresponding to three extrema of the free energy. The equilibrium and
+metastable configurations, which are magnetized approximately parallel and
+antiparallel to the applied field, respectively, both correspond to local
+free-energy minima. The third extremum configuration is the saddle point
+separating these minima. It is also called the transition state for
+magnetization reversal. The free-energy difference between the metastable and
+transition-state configurations determines the thermal stability of the magnet.
+However, it is difficult to determine the location of the transition state in
+both experiments and numerical simulations. Here it is shown that the
+computational Projective Dynamics method, applied to the time dependence of the
+total magnetization, can be used to determine the transition state. From
+large-scale micromagnetic simulations of a simple model of magnetic nanowires
+with no crystalline anisotropy, the magnetization associated with the
+transition state is found to be linearly dependent on temperature, and the
+free-energy barrier is found to be dominated by the entropic contribution at
+reasonable temperatures and external fields. The effect of including
+crystalline anisotropy is also discussed. Finally, the influence of the spin
+precession on the transition state is determined by comparison of the
+micromagnetic simulations to kinetic Monte Carlo simulations of precession-free
+(overdamped) dynamics.",0209166v1
+2002-09-13,Quantum Monte Carlo study of S=1/2 weakly-anisotropic antiferromagnets on the square lattice,"We study the finite-temperature behaviour of two-dimensional S=1/2 Heisenberg
+antiferromagnets with very weak easy-axis and easy-plane exchange anisotropies.
+By means of quantum Monte Carlo simulations, based on the continuous-time loop
+and worm algorithm, we obtain a rich set of data that allows us to draw
+conclusions about both the existence and the type of finite-temperature
+transition expected in the considered models. We observe that the essential
+features of the Ising universality class, as well as those of the
+Berezinskii-Kosterlitz-Thouless (BKT) one, are preserved even for anisotropies
+as small as 10^{-3} times the exchange integral; such outcome, being referred
+to the most quantum case S=1/2, rules out the possibility for quantum
+fluctuations to destroy the long or quasi-long range order, whose onset is
+responsible for the Ising or BKT transition, no matter how small the
+anisotropy. Besides this general issue, we use our results to extract, out of
+the isotropic component, the features which are peculiar to weakly anisotropic
+models, with particular attention for the temperature region immediately above
+the transition. By this analysis we aim to give a handy tool for understanding
+the experimental data relative to those real compounds whose anisotropies are
+too weak for a qualitative description to accomplish the goal of singling out
+the genuinely two-dimensional critical behaviour.",0209316v2
+2003-10-14,"Exchange anisotropy, disorder and frustration in diluted, predominantly ferromagnetic, Heisenberg spin systems","Motivated by the recent suggestion of anisotropic effective exchange
+interactions between Mn spins in Ga$_{1-x}$Mn$_x$As (arising as a result of
+spin-orbit coupling), we study their effects in diluted Heisenberg spin
+systems. We perform Monte Carlo simulations on several phenomenological model
+spin Hamiltonians, and investigate the extent to which frustration induced by
+anisotropic exchanges can reduce the low temperature magnetization in these
+models and the interplay of this effect with disorder in the exchange. In a
+model with low coordination number and purely ferromagnetic (FM) exchanges, we
+find that the low temperature magnetization is gradually reduced as exchange
+anisotropy is turned on. However, as the connectivity of the model is
+increased, the effect of small-to-moderate anisotropy is suppressed, and the
+magnetization regains its maximum saturation value at low temperatures unless
+the distribution of exchanges is very wide. To obtain significant suppression
+of the low temperature magnetization in a model with high connectivity, as is
+found for long-range interactions, we find it necessary to have both
+ferromagnetic and antiferromagnetic (AFM) exchanges (e.g. as in the RKKY
+interaction). This implies that disorder in the sign of the exchange
+interaction is much more effective in suppressing magnetization at low
+temperatures than exchange anisotropy.",0310322v1
+2004-05-04,Effect of extra electrons on the exchange and magnetic anisotropy in the anionic single-molecule magnet Mn12,"To understand the effect of molecular environment on the electronic and
+magnetic properties of the single-molecule magnet (SMM) Mn$_{12}$, we explore
+two possible means for adding extra electrons to molecule. We explore both
+substitution of Mn ions by Fe ions and the inclusion of neighboring electronic
+donors. For both possibilities we calculate, within density-functional theory,
+the electronic structure, the total ground-state spin and ordering, the
+magnetic anisotropy barrier, the transverse magnetic anisotropy parameter $E$
+which is responsible for some measured tunneling, and the tilting angle of the
+easy axis from the z axis. Our calculations show that the total spin increases
+with increasing number of extra electrons except for the case of Mn$_{8}$Fe$_4$
+where the resulting ground state has a low spin. The calculated energy gaps
+between the unoccupied and the occupied orbitals exhibit no clear trend as a
+function of number of extra electrons. The calculated magnetic anisotropy
+barrier decreases with increasing number of extra electrons and can be directly
+chased to a quenching of Jahn-Teller distortions at the sites where the
+additional electrons are localized. The values of $E$ and the easy-axis tilting
+angles for the geometries with one- and two-extra electrons are significantly
+larger than those induced by solvent disorder.",0405059v1
+2005-07-30,GaMnAs grown on (311) GaAs substrates: modified Mn incorporation and new magnetic anisotropies,"We report the results of a detailed study of the structural, magnetic and
+magnetotransport properties of as-grown and annealed Ga0.91Mn0.09As thin films
+grown on (311)A and (311)B GaAs substrates. The high Curie temperature and hole
+density of the (311)B material are comparable to those of GaMnAs grown on (001)
+GaAs under the same growth conditions, while they are much lower for the (311)A
+material. We find evidence that Mn incorporation is more efficient for (311)B
+than for (001) and significantly less efficient for (311)A which is consistent
+with the bonding on these surfaces. This indicates that growth on (311)B may be
+a route to increased Curie temperatures in GaMnAs. A biaxial magnetic
+anisotropy is observed for the (311) material with easy axes along the [010]
+and [001] out-of-plane directions. An additional uniaxial in-plane anisotropy
+is also observed with the easy axis along for the (311)A material, and along
+for the (311)B material. This new observation may be of importance for the
+resolution of the outstanding problem of the origin of uniaxial anisotropy in
+(001) GaMnAs.",0508021v1
+2005-10-25,Effective Electrostatic Interactions in Solutions of Polyelectrolyte Stars with Rigid Rodlike Arms,"In solutions of star-branched polyelectrolytes, electrostatic interactions
+between charged arms on neighboring stars can compete with intra-star
+interactions and rotational entropy to induce anisotropy in the orientational
+distribution of arms. For model stars comprising rigid rodlike arms with evenly
+spaced charged monomers interacting via an effective screened-Coulomb (Yukawa)
+potential, we explore the influence of arm orientational anisotropy on
+effective star-star interactions. Monte Carlo simulation and density-functional
+theory are used to compute arm orientational distributions and effective pair
+potentials between weakly charged stars. The degree of anisotropy is found to
+increase with the strength of electrostatic interactions and proximity of the
+stars. As two stars begin to overlap, the forward arms are pushed back by
+inter-star arm-arm repulsion, but partially interdigitate due to rotational
+entropy. At center-center separations approaching complete overlap, the arms
+relax to an isotropic distribution. For nonoverlapping stars,
+anisotropy-induced changes in intra- and inter-star arm-arm interactions
+largely cancel and the effective pair interactions are then well approximated
+by a simple Yukawa potential, as predicted by linear response theory for a
+continuum model of isotropic stars [A. R. Denton, Phys. Rev. E 67, 11804
+(2003)]. For overlapping stars, the effective pair interactions in the simple
+rigid-arm-Yukawa model agree closely with simulations of a molecular model that
+includes flexible arms and explicit counterions [A. Jusufi, C. N. Likos, and H.
+Lowen, Phys. Rev. Lett. 88, 018301 (2002); J. Chem. Phys. 116, 11011 (2002)].",0510678v1
+2006-01-25,Spin anisotropy effects in dimer single molecule magnets,"We present a model of equal spin $s_1$ dimer single molecule magnets. The
+spins within each dimer interact via the Heisenberg and the most general set of
+four quadratic anisotropic spin interactions with respective strengths $J$ and
+$\{J_j\}$, and with the magnetic induction ${\bf B}$. We solve the model
+exactly for $s_1=1/2, 1, 5/2$, and for antiferromagnetic Heisenberg couplings
+($J<0$), present ${\bf M}({\bf B})$ curves at low $T$ for these cases. Low-$T$
+$C_V({\bf B})$ curves for $s_1=1/2$ and electron paramagnetic susceptibility
+$\chi({\bf B},\omega)$ for $s_1=1$ are also provided. For weak anisotropy
+interactions, we employ a perturbative treatment, and show that the Hartree and
+extended Hartree approximations lead to reliable analytic results at low $T$
+and large $B$ for these quantities and for the inelastic neutron scattering
+cross-section $S({\bf B}, {\bf q},\omega)$. Our results are discussed with
+regard to existing ${\bf M}({\bf B})$ experiments on $s_1=5/2$ Fe$_2$ dimer
+single molecule magnets, and suggest that one of them contains a substantial
+amount of single-ion anisotropy, without any sizeable global spin anisotropy.
+We urge further experiments of the above types on single crystals of Fe$_2$ and
+on some $s_=9/2$ [Mn$_4$]$_2$ dimers, in order to elucidate the precise values
+of the various microscopic interactions.",0601591v1
+2006-03-08,Is it really possible to grow isotropic on-lattice diffusion-limited aggregates?,"In a recent paper (Bogoyavlenskiy V A 2002 \JPA \textbf{35} 2533), an
+algorithm aiming to generate isotropic clusters of the on-lattice
+diffusion-limited aggregation (DLA) model was proposed. The procedure consists
+of aggregation probabilities proportional to the squared number of occupied
+sites ($k^2$). In the present work, we analyzed this algorithm using the noise
+reduced version of the DLA model and large scale simulations. In the noiseless
+limit, instead of isotropic patterns, a $45^\circ$ ($30^\circ$) rotation in the
+anisotropy directions of the clusters grown on square (triangular) lattices was
+observed. A generalized algorithm, in which the aggregation probability is
+proportional to $k^\nu$, was proposed. The exponent $\nu$ has a nonuniversal
+critical value $\nu_c$, for which the patterns generated in the noiseless limit
+exhibit the original (axial) anisotropy for $\nu<\nu_c$ and the rotated one
+(diagonal) for $\nu>\nu_c$. The values $\nu_c = 1.395\pm0.005$ and $\nu_c =
+0.82\pm 0.01$ were found for square and triangular lattices, respectively.
+Moreover, large scale simulations show that there are a nontrivial relation
+between noise reduction and anisotropy direction. The case $\nu=2$ (\bogo's
+rule) is an example where the patterns exhibit the axial anisotropy for small
+and the diagonal one for large noise reduction.",0603218v1
+2006-05-19,Spin-flop transition in antiferromagnetic multilayers,"A comprehensive theoretical investigation on the field-driven reorientation
+transitions in uniaxial multilayers with antiferromagnetic coupling is
+presented. It is based on a complete survey of the one-dimensional solutions
+for the basic phenomenological (micromagnetic) model that describes the
+magnetic properties of finite stacks made from ferromagnetic layers coupled
+antiferromagnetically through spacer layers. The general structure of the phase
+diagrams is analysed. At a high ratio of uniaxial anisotropy to
+antiferromagnetic interlayer exchange, only a succession of collinear magnetic
+states is possible. With increasing field first-order (metamagnetic)
+transitions occur from the antiferromagnetic ground-state to a set of
+degenerate ferrimagnetic states and to the saturated ferromagnetic state. At
+low anisotropies, a first-order transition from the antiferromagnetic
+ground-state to an inhomogeneous spin-flop state occurs. Between these two
+regions, transitional magnetic phases occupy the range of intermediate
+anisotropies. Detailed and quantitative phase diagrams are given for the basic
+model of antiferromagnetic multilayer systems with N = 2 to 16 layers. The
+connection of the phase diagrams with the spin-reorientation transitions in
+bulk antiferromagnets is discussed. The limits of low anisotropy and large
+numbers of layers are analysed by two different representations of the magnetic
+energy, namely, in terms of finite chains of staggered vectors and in a general
+continuum form. It is shown that the phenomena widely described as ``surface
+spin-flop'' are driven only by the cut exchange interactions and the
+non-compensated magnetic moment at the surface layers of a stacked
+antiferromagnetic system.",0605493v1
+2006-06-10,Topological solitons in highly anisotropic two dimensional ferromagnets,"e study the solitons, stabilized by spin precession in a classical
+two--dimensional lattice model of Heisenberg ferromagnets with non-small
+easy--axis anisotropy. The properties of such solitons are treated both
+analytically using the continuous model including higher then second powers of
+magnetization gradients, and numerically for a discrete set of the spins on a
+square lattice. The dependence of the soliton energy $E$ on the number of spin
+deviations (bound magnons) $N$ is calculated. We have shown that the
+topological solitons are stable if the number $N$ exceeds some critical value
+$N_{\rm{cr}}$. For $N < N_{\rm{cr}}$ and the intermediate values of anisotropy
+constant $K_{\mathrm{eff}} <0.35J$ ($J$ is an exchange constant), the soliton
+properties are similar to those for continuous model; for example, soliton
+energy is increasing and the precession frequency $ \omega (N)$ is decreasing
+monotonously with $N$ growth. For high enough anisotropy $K_{\mathrm{eff}} >
+0.6 J$ we found some fundamentally new soliton features absent for continuous
+models incorporating even the higher powers of magnetization gradients. For
+high anisotropy, the dependence of soliton energy E(N) on the number of bound
+magnons become non-monotonic, with the minima at some ""magic"" numbers of bound
+magnons. Soliton frequency $\omega (N)$ have quite irregular behavior with
+step-like jumps and negative values of $\omega $ for some regions of $N$. Near
+these regions, stable static soliton states, stabilized by the lattice effects,
+exist.",0606263v1
+2006-07-24,Effect of Y substitution on the structural and magnetic properties of Dy1-xYxCo5 compounds,"Structural and magnetization studies were carried out on Dy1-xYxCo5 [x = 0,
+0.2, 0.4, 0.6, 0.8, 1] compounds which crystallize in the hexagonal CaCu5-type
+structure. Lattice parameters and unit-cell volume increase with Y
+concentration. Large thermomagnetic irreversibility between the field-cooled
+and the zero-field cooled magnetization data has been observed in all the
+compounds, which has been attributed to the domain wall pinning effect.
+Temperature dependence of magnetization data shows that except DyCo5 and YCo5,
+all the compounds show spin reorientation transitions in the range of 5-300 K.
+The spin reorientation temperature decreases from 266 K for x=0.2 to 100 K for
+x=0.8. Powder x-ray diffractograms of the magnetically aligned samples show
+that DyCo5 has planar anisotropy at room temperature whereas all the other
+compounds possess axial anisotropy. The spin reorientation transition has been
+attributed to a change in the easy magnetization direction from the ab-plane to
+the c-axis, as the temperature is increased. The anisotropy field and the first
+order anisotropy constant are found to be quite high in all the compounds
+except DyCo5. The magnetic properties have been explained by taking into
+account the variations in contributions arising from the rare earth and
+transition metal sublattices.",0607597v1
+2006-08-18,Influence of external flows on crystal growth: numerical investigation,"We use a combined phase-field/lattice-Boltzmann scheme [D. Medvedev, K.
+Kassner, Phys. Rev. E {\bf 72}, 056703 (2005)] to simulate non-facetted crystal
+growth from an undercooled melt in external flows. Selected growth parameters
+are determined numerically.
+  For growth patterns at moderate to high undercooling and relatively large
+anisotropy, the values of the tip radius and selection parameter plotted as a
+function of the Peclet number fall approximately on single curves. Hence, it
+may be argued that a parallel flow changes the selected tip radius and growth
+velocity solely by modifying (increasing) the Peclet number. This has
+interesting implications for the availability of current selection theories as
+predictors of growth characteristics under flow.
+  At smaller anisotropy, a modification of the morphology diagram in the plane
+undercooling versus anisotropy is observed. The transition line from dendrites
+to doublons is shifted in favour of dendritic patterns, which become faster
+than doublons as the flow speed is increased, thus rendering the basin of
+attraction of dendritic structures larger.
+  For small anisotropy and Prandtl number, we find oscillations of the tip
+velocity in the presence of flow. On increasing the fluid viscosity or
+decreasing the flow velocity, we observe a reduction in the amplitude of these
+oscillations.",0608430v1
+2006-10-30,Revised theory of the magnetic surface anisotropy of impurities in metallic mesoscopic samples,"In several experiments the magnitude of the contribution of magnetic
+impurities to the Kondo resistivity shows size dependence in mesoscopic
+samples. It was suggested ten years ago that magnetic surface anisotropy can be
+responsible for the size dependence in cases where there is strong spin-orbit
+interaction in the metallic host. The anisotropy energy has the form $\Delta
+E=K_d ({\bf n}{\bf S})^2$ where ${\bf n}$ is the vector perpendicular to the
+plane surface, ${\bf S}$ is the spin of the magnetic impurity and $K_d>0$ is
+inversely proportional to distance $d$ measured from the surface. It has been
+realized that in the tedious calculation an unjustified approximation was
+applied for the hybridizations of the host atom orbitals with the conduction
+electrons which depend on the position of the host atoms. Namely, the momenta
+of the electrons were replaced by the Fermi momentum $k_F$. That is
+reinvestigated considering the $k$-dependence which leads to singular energy
+integrals and in contrary to the previous result $K_d$ is oscillating like
+$\sin (2 k_F d)$ and the distance dependence goes like $1/d^3$ in the
+asymptotic region. As the anisotropy is oscillating, for integer spin the
+ground state is either a singlet or a doublet depending on distance $d$, but in
+the case of the doublet there is no direct electron induced transition between
+those two states at zero temperature. Furthermore, for half-integer ($S > 1/2$)
+spin it is always a doublet with direct transition only in half of the cases.",0610843v2
+2007-01-04,Exact solution of the mixed-spin Ising model on a decorated square lattice with two different kinds of decorating spins on horizontal and vertical bonds,"The mixed spin-(1/2, S_B, S_C) Ising model on a decorated square lattice with
+two different kinds of decorating spins S_B and S_C placed on its horizontal
+and vertical bonds, respectively, is exactly solved by establishing a precise
+mapping relationship with the corresponding spin-1/2 Ising model on an
+anisotropic square (rectangular) lattice. The effect of uniaxial single-ion
+anisotropy acting on both types of decorating spins S_B and S_C is examined in
+particular. If decorating spins S_B and S_C are integer and half-odd-integer,
+respectively, or if the reverse is the case, the model under investigation
+displays a very peculiar critical behavior beared on the spontaneously ordered
+'quasi-1D' spin system, which appears as a result of the single-ion anisotropy
+strengthening. We have found convincing evidence that this remarkable
+spontaneous ordering virtually arises even though all integer-valued decorating
+spins tend towards their 'non-magnetic' spin state S=0 and the system becomes
+disordered only upon further increase of the single-ion anisotropy. The
+single-ion anisotropy parameter is also at an origin of various temperature
+dependences of the total magnetization when imposing the pure ferrimagnetic or
+the mixed ferro-ferrimagnetic character of the spin arrangement.",0701071v2
+1992-11-19,Tunneling in Anisotropic Cosmological Models,"Tunneling rate is investigated in homogenous and anisotropic cosmologies. The
+calculations is done by two methods: Euclidean and Hamiltonian approaches. It
+is found that the probability decreases exponentialy as anisotropy is
+increased.",9211024v1
+1997-07-10,A fully covariant description of CMB anisotropies,"Starting from the exact non-linear description of matter and radiation, a
+fully covariant and gauge-invariant formula for the observed temperature
+anisotropy of the cosmic microwave background (CBR) radiation, expressed in
+terms of the electric ($E_{ab}$) and magnetic ($H_{ab}$) parts of the Weyl
+tensor, is obtained by integrating photon geodesics from last scattering to the
+point of observation today. This improves and extends earlier work by Russ et
+al where a similar formula was obtained by taking first order variations of the
+redshift. In the case of scalar (density) perturbations, $E_{ab}$ is related to
+the harmonic components of the gravitational potential $\Phi_k$ and the usual
+dominant Sachs-Wolfe contribution $\delta T_R/\bar{T}_R\sim\Phi_k$ to the
+temperature anisotropy is recovered, together with contributions due to the
+time variation of the potential (Rees-Sciama effect), entropy and velocity
+perturbations at last scattering and a pressure suppression term important in
+low density universes. We also explicitly demonstrate the validity of assuming
+that the perturbations are adiabatic at decoupling and show that if the surface
+of last scattering is correctly placed and the background universe model is
+taken to be a flat dust dominated Friedmann-Robertson-Walker model (FRW), then
+the large scale temperature anisotropy can be interpreted as being due to the
+motion of the matter relative to the surface of constant temperature which
+defines the surface of last scattering on those scales.",9707022v1
+1998-03-13,The Anisotropic Wilson Gauge Action,"Anisotropic lattices, with a temporal lattice spacing smaller than the
+spatial one, allow precision Monte Carlo calculations of problems that are
+difficult to study otherwise: heavy quarks, glueballs, hybrids, and high
+temperature thermodynamics, for example. We here perform the first step
+required for such studies with the (quenched) Wilson gauge action, namely, the
+determination of the renormalized anisotropy $\xi$ as a function of the bare
+anisotropy $\xi_0$ and the coupling. By, essentially, comparing the
+finite-volume heavy quark potential where the quarks are separated along a
+spatial direction with that where they are separated along the time direction,
+we determine the relation between $\xi$ and $\xi_0$ to a fraction of 1% for
+weak and to 1% for strong coupling. We present a simple parameterization of
+this relation for $1\leq \xi \leq 6$ and $5.5 \leq \beta \leq \infty$, which
+incorporates the known one-loop result and reproduces our non-perturbative
+determinations within errors. Besides solving the problem of how to choose the
+bare anisotropies if one wants to take the continuum limit at fixed
+renormalized anisotropy, this parameterization also yields accurate estimates
+of the derivative $\partial\xi_0/\partial\xi$ needed in thermodynamic studies.",9803010v2
+2001-07-02,Numerical study of O(a) improved Wilson quark action on anisotropic lattice,"The $O(a)$ improved Wilson quark action on the anisotropic lattice is
+investigated. We carry out numerical simulations in the quenched approximation
+at three values of lattice spacing ($a_{\sigma}^{-1}=1$--2 GeV) with the
+anisotropy $\xi=a_{\sigma}/a_{\tau}=4$, where $a_{\sigma}$ and $a_{\tau}$ are
+the spatial and the temporal lattice spacings, respectively. The bare
+anisotropy $\gamma_F$ in the quark field action is numerically tuned by the
+dispersion relation of mesons so that the renormalized fermionic anisotropy
+coincides with that of gauge field. This calibration of bare anisotropy is
+performed to the level of 1 % statistical accuracy in the quark mass region
+below the charm quark mass. The systematic uncertainty in the calibration is
+estimated by comparing the results from different types of dispersion
+relations, which results in 3 % on our coarsest lattice and tends to vanish in
+the continuum limit. In the chiral limit, there is an additional systematic
+uncertainty of 1 % from the chiral extrapolation.
+  Taking the central value $\gamma_F=\gamma_F^*$ from the result of the
+calibration, we compute the light hadron spectrum. Our hadron spectrum is
+consistent with the result by UKQCD Collaboration on the isotropic lattice. We
+also study the response of the hadron spectrum to the change of anisotropic
+parameter, $\gamma_F \to \gamma_F^* + \delta\gamma_F$. We find that the change
+of $\gamma_F$ by 2 % induces a change of 1 % in the spectrum for physical quark
+masses. Thus the systematic uncertainty on the anisotropic lattice, as well as
+the statistical one, is under control.",0107001v1
+2004-12-03,Lattice Study of Anisotropic QED-3,"We present results from a Monte Carlo simulation of non-compact lattice QED
+in 3 dimensions on a $16^3$ lattice in which an explicit anisotropy between $x$
+and $y$ hopping terms has been introduced into the action. This formulation is
+inspired by recent formulations of anisotropic QED$_3$ as an effective theory
+of the non-superconducting portion of the cuprate phase diagram, with
+relativistic fermion degrees of freedom defined near the nodes of the gap
+function on the Fermi surface, and massless photon degrees of freedom
+reproducing the dynamics of the phase disorder of the superconducting order
+parameter. Using a parameter set corresponding to broken chiral symmetry in the
+isotropic limit, our results show that the renormalised anisotropy, defined in
+terms of the ratio of correlation lengths of gauge invariant bound states in
+the $x$ and $y$ directions, exceeds the explicit anisotropy $\kappa$ introduced
+in the lattice action, implying in contrast to recent analytic results that
+anisotropy is a relevant deformation of QED$_3$. There also appears to be a
+chiral symmetry restoring phase transition at $\kappa_c\simeq4.5$, implying
+that the pseudogap phase persists down to T=0 in the cuprate phase diagram.",0412009v2
+1997-01-29,Symmetries of BFKL Equation,"We discuss the algebraic structure of the spin chains related to high energy
+scattering in QCD. We study the sl(2) Yangian symmetry and possible
+generalizations to nonzero spin and anisotropy parameter.",9701174v1
+2006-11-28,On the Dirichlet problem of Landau-Lifshitz-Maxwell equations,"We prove the existence and uniqueness of non-trivial stable solutions to
+Landau-Lifshitz-Maxwell equations with Dirichlet boundary condition for large
+anisotropies and small domains, where the domains are non-simply connected.",0611844v1
+2000-01-19,Persistence of small-scale anisotropies and anomalous scaling in a model of magnetohydrodynamics turbulence,"The problem of anomalous scaling in magnetohydrodynamics turbulence is
+considered within the framework of the kinematic approximation, in the presence
+of a large-scale background magnetic field. The velocity field is Gaussian,
+$\delta$-correlated in time, and scales with a positive exponent $\xi$.
+Explicit inertial-range expressions for the magnetic correlation functions are
+obtained; they are represented by superpositions of power laws with
+non-universal amplitudes and universal (independent of the anisotropy and
+forcing) anomalous exponents. The complete set of anomalous exponents for the
+pair correlation function is found non-perturbatively, in any space dimension
+$d$, using the zero-mode technique. For higher-order correlation functions, the
+anomalous exponents are calculated to $O(\xi)$ using the renormalization group.
+The exponents exhibit a hierarchy related to the degree of anisotropy; the
+leading contributions to the even correlation functions are given by the
+exponents from the isotropic shell, in agreement with the idea of restored
+small-scale isotropy. Conversely, the small-scale anisotropy reveals itself in
+the odd correlation functions : the skewness factor is slowly decreasing going
+down to small scales and higher odd dimensionless ratios (hyperskewness etc.)
+dramatically increase, thus diverging in the $r\to 0$ limit.",0001039v1
+2000-07-12,"""Toy models"" of turbulent convection and the hypothesis of the local isotropy restoration","A brief review is given of recent results devoted to the effects of
+large-scale anisotropy on the inertial-range statistics of the passive scalar
+quantity $\theta(t,{\bf x})$, advected by the synthetic turbulent velocity
+field with the covariance $\propto\delta(t-t')|{\bf x}-{\bf x'}|^{\eps}$.
+Inertial-range anomalous scaling behavior is established, and explicit
+asymptotic expressions for the structure functions $ S_n (\r) \equiv <
+[\theta(t,{\bf x}+\r)-\theta(t,{\bf x})]^{n}>$ are obtained; they are
+represented by superpositions of power laws with universal (independent of the
+anisotropy parameters) anomalous exponents, calculated to the first order in
+$\eps$ in any space dimension. The exponents are associated with tensor
+composite operators built of the scalar gradients, and exhibit a kind of
+hierarchy related to the degree of anisotropy: the less is the rank, the less
+is the dimension and, consequently, the more important is the contribution to
+the inertial-range behavior. The leading terms of the even (odd) structure
+functions are given by the scalar (vector) operators. The small-scale
+anisotropy reveals itself in odd correlation functions: for the incompressible
+velocity field, $S_{3}/S_{2}^{3/2}$ decreases going down towards to the depth
+of the inertial range, while the higher-order odd ratios increase; if the
+compressibility is strong enough, the skewness factor also becomes increasing.",0007015v1
+2007-01-03,On the angular distribution and spin polarization of the photoelectrons from semi-filled shell atoms,"We present here the results of calculations of photoelectrons' angular
+anisotropy and spin-polarization parameters for a number of semi-filled shell
+atoms. We consider ionization of outer or in some cases next to the outer
+electrons in a number of elements from I, V, and VI groups of the Periodic
+Table. All calculations are performed with account of multi-electron
+correlations in the frame of the Spin Polarized version of the Random Phase
+Approximation with Exchange - SP RPAE. We consider the dipole angular
+distribution and spin polarization of photoelectrons from semi-filled subshells
+and from closed shells that are neighbors to the semi-filled shells. We have
+considered also angular anisotropy and spin-polarization of photoelectrons from
+some excited atoms that are formed by spin-flip of one of the outer electrons.
+To check the accuracy and consistency of the applied SP RPAE approach and to
+see the role of the nuclear charge variation only, we have calculated the
+dipole angular anisotropy and spin-polarization parameters of 3p - electrons in
+K and compare them to Ar and K+ that have the same configuration. Entirely, we
+have calculated the angular anisotropy and spin-polarization parameters for
+following subshells of atoms N (2p), P (3p), Ar (3p), K+(3p), K(3p), Cr(3p,
+3d), Cr*(3d), Mn(3p, 3d), As(3d, 4p), Mo(4p, 4d), Mo*(4d), Tc(4p, 4d), Sb(4d,
+5p), Eu(4f). The peculiarities of obtained parameters as function of photon
+frequencies are discussed, as well as some specific features of considered
+semi-filled shell objects.",0701040v1
+2007-05-18,Angular anisotropy of the fusion-fission and quasifission fragments,"The anisotropy in the angular distribution of the fusion-fission and
+quasifission fragments for the $^{16}$O+$^{238}$U, $^{19}$F+$^{208}$Pb and
+$^{32}$S+$^{208}$Pb reactions is studied by analyzing the angular momentum
+distributions of the dinuclear system and compound nucleus which are formed
+after capture and complete fusion, respectively. The orientation angles of
+axial symmetry axes of colliding nuclei to the beam direction are taken into
+account for the calculation of the variance of the projection of the total spin
+onto the fission axis. It is shown that the deviation of the experimental
+angular anisotropy from the statistical model picture is connected with the
+contribution of the quasifission fragments which is dominant in the
+$^{32}$S+$^{208}$Pb reaction. Enhancement of anisotropy at low energies in the
+$^{16}$O+$^{238}$U reaction is connected with quasifission of the dinuclear
+system having low temperature and effective moment of inertia.",0705.2748v1
+2007-06-05,A note on the large-angle anisotropies in the WMAP cut-sky maps,"Recent analyses of the WMAP data seem to indicate the possible presence of
+large-angle anisotropy in the Universe. If confirmed, these can have important
+consequences for our understanding of the Universe. A number of attempts have
+recently been made to establish the reality and nature of such anisotropies in
+the CMB data. Among these is a directional indicator recently proposed by the
+authors. A distinctive feature of this indicator is that it can be used to
+generate a sky map of the large-scale anisotropies of the CMB maps. Applying
+this indicator to full-sky temperature maps we found a statistically
+significant preferred direction. The full-sky maps used in these analyses are
+known to have residual foreground contamination as well as complicated noise
+properties. Thus, here we performed the same analysis for a map where regions
+with high foreground contamination were removed. We find that the main feature
+of the full-sky analysis, namely the presence of a significant axis of
+asymmetry, is robust with respect to this masking procedure. Other subtler
+anomalies of the full-sky are on the other hand no longer present.",0706.0575v1
+2007-06-14,Bianchi Model CMB Polarization and its Implications for CMB Anomalies,"We derive the CMB radiative transfer equation in the form of a multipole
+hierarchy in the nearly-Friedmann-Robertson-Walker limit of homogeneous, but
+anisotropic, universes classified via their Bianchi type. Compared with
+previous calculations, this allows a more sophisticated treatment of
+recombination, produces predictions for the polarization of the radiation, and
+allows for reionization. Our derivation is independent of any assumptions about
+the dynamical behaviour of the field equations, except that it requires
+anisotropies to be small back to recombination; this is already demanded by
+observations.
+  We calculate the polarization signal in the Bianchi VIIh case, with the
+parameters recently advocated to mimic the several large-angle anomalous
+features observed in the CMB. We find that the peak polarization signal is ~
+1.2 micro K for the best-fit model to the temperature anisotropies, and is
+mostly confined to multipoles l<10. Remarkably, the predicted large-angle EE
+and TE power spectra in the Bianchi model are consistent with WMAP observations
+that are usually interpreted as evidence of early reionization. However, the
+power in B-mode polarisation is predicted to be similar to the E-mode power and
+parity-violating correlations are also predicted by the model; the WMAP
+non-detection of either of these signals casts further strong doubts on the
+veracity of attempts to explain the large-angle anomalies with global
+anisotropy. On the other hand, given that there exist further dynamical degrees
+of freedom in the VIIh universes that are yet to be compared with CMB
+observations, we cannot at this time definitively reject the anisotropy
+explanation.",0706.2075v2
+2007-08-30,Some doubts on the validity of the foreground Galactic contribution subtraction from microwave anisotropies,"The Galactic foreground contamination in CMBR anisotropies, especially from
+the dust component, is not easily separable from the cosmological or
+extragalactic component. In this paper, some doubts will be raised concerning
+the validity of the methods used to date to remove Galactic dust emission in
+order to show that none of them achieves its goal.
+  First, I review the recent bibliography on the topic and discuss critically
+the methods of foreground subtraction: the cross-correlation with templates,
+analysis assuming the spectral shape of the Galactic components, the ""maximum
+entropy method"", ""internal linear combination"", and ""wavelet-based high
+resolution fitting of internal templates"". Second, I analyse the galactic
+latitude dependence from WMAP data. The frequency dependence is discussed with
+the data in the available literature. The result is that all methods of
+subtracting the Galactic contamination are inaccurate. The galactic latitude
+dependence analysis or the frequency dependence of the anisotropies in the
+range 50-250 GHz put a constraint on the maximum Galactic contribution in the
+power spectrum to be less than a ~10% (68% C. L.) for a ~1 degree scale, and
+possibly higher for larger scales.
+  The origin of most of the signal in the CMBR anisotropies is not Galactic. In
+any case, the subtraction of the Galaxy is not accurate enough to allow a
+""precision Cosmology""; other sources of contamination (extragalactic, solar
+system) are also present.",0708.4133v2
+2007-10-23,"Three-electron anisotropic quantum dots in variable magnetic fields: exact results for excitation spectra, spin structures, and entanglement","Exact-diagonalization calculations for N=3 electrons in anisotropic quantum
+dots, covering a broad range of confinement anisotropies and strength of
+inter-electron repulsion, are presented for zero and low magnetic fields. The
+excitation spectra are analyzed as a function of the strength of the magnetic
+field and for increasing quantum-dot anisotropy. Analysis of the intrinsic
+structure of the many-body wave functions through spin-resolved two-point
+correlations reveals that the electrons tend to localize forming Wigner
+molecules. For certain ranges of dot parameters (mainly at strong anisotropy),
+the Wigner molecules acquire a linear geometry, and the associated wave
+functions with a spin projection S_z=1/2 are similar to the representative
+class of strongly entangled states referred to as W-states. For other ranges of
+parameters (mainly at intermediate anisotropy), the Wigner molecules exhibit a
+more complex structure consisting of two mirror isosceles triangles. This
+latter structure can be viewed as an embryonic unit of a zig-zag Wigner crystal
+in quantum wires. The degree of entanglement in three-electron quantum dots can
+be quantified through the use of the von Neumann entropy.",0710.4325v1
+2007-12-15,Single-ion and exchange anisotropy effects and multiferroic behavior in high-symmetry tetramer single molecule magnets,"We study single-ion and exchange anisotropy effects in equal-spin $s_1$
+tetramer single molecule magnets exhibiting $T_d$, $D_{4h}$, $D_{2d}$,
+$C_{4h}$, $C_{4v}$, or $S_4$ ionic point group symmetry. We first write the
+group-invariant quadratic single-ion and symmetric anisotropic exchange
+Hamiltonians in the appropriate local coordinates. We then rewrite these local
+Hamiltonians in the molecular or laboratory representation, along with the
+Dzyaloshinskii-Moriay (DM) and isotropic Heisenberg, biquadratic, and
+three-center quartic Hamiltonians. Using our exact, compact forms for the
+single-ion spin matrix elements, we evaluate the eigenstate energies
+analytically to first order in the microscopic anisotropy interactions,
+corresponding to the strong exchange limit, and provide tables of simple
+formulas for the energies of the lowest four eigenstate manifolds of
+ferromagnetic (FM) and anitiferromagnetic (AFM) tetramers with arbitrary $s_1$.
+For AFM tetramers, we illustrate the first-order level-crossing inductions for
+$s_1=1/2,1,3/2$, and obtain a preliminary estimate of the microscopic
+parameters in a Ni$_4$ from a fit to magnetization data.
+  Accurate analytic expressions for the thermodynamics, electron paramagnetic
+resonance absorption and inelastic neutron scattering cross-section are given,
+allowing for a determination of three of the microscopic anisotropy
+interactions from the second excited state manifold of FM tetramers. We also
+predict that tetramers with symmetries $S_4$ and $D_{2d}$ should exhibit both
+DM interactions and multiferroic states, and illustrate our predictions for
+$s_1=1/2, 1$.",0712.2518v2
+2008-01-08,Kinematic Sunyaev-Zeldovich Cosmic Microwave Background Temperature Anisotropies Generated by Gas in Cosmic Structures,"If the gas in filaments and halos shares the same velocity field than the
+luminous matter, it will generate measurable temperature anisotropies due to
+the Kinematic Sunyaev-Zeldovich effect. We compute the distribution function of
+the KSZ signal produced by a typical filament and show it is highly
+non-gaussian. The combined contribution of the Thermal and Kinematic SZ effects
+of a filament of size $L\simeq 5$Mpc and electron density $n_e\simeq
+10^3m^{-3}$ could explain the cold spots of $\delta\sim -200\mu$K on scales of
+30' found in the Corona Borealis Supercluster by the VSA experiment. PLANCK,
+with its large resolution and frequency coverage, could provide the first
+evidence of the existence of filaments in this region. The KSZ contribution of
+the network of filaments and halo structures to the radiation power spectrum
+peaks around $l\sim 400$, a scale very different from that of clusters of
+galaxies, with a maximum amplitude $l(l+1)C_l/2\pi\sim 10-25 (\mu K)^2$,
+depending on model parameters, i.e., $\sigma_8$ and the Jeans length. About 80%
+of the signal comes from filaments with redshift $z\le 0.1$. Adding this
+component to the intrinsic Cosmic Microwave Background temperature anisotropies
+of the concordance model improves the fit to WMAP 3yr data by
+$\Delta\chi^2\simeq 1$. The improvement is not statistically significant but a
+more systematic study could demonstrate that gas could significantly contribute
+to the anisotropies measured by WMAP.",0801.1198v1
+2008-04-30,Coinage-metal capping effects on the spin-reorientations of Co/Ru(0001),"Thin films of Co/Ru(0001) are known to exhibit an unusual spin reorientation
+transition (SRT) coupled to the completion of Co atomic layers for Co
+thicknesses under 4 layers. By means of spin-polarized low-energy electron
+microscopy, we follow in real space the magnetization orientation during the
+growth of atomically thick capping layers on Co/Ru(0001). Capping with
+coinage-metal (Cu, Ag, Au) elements modifies the SRT depending on the Co and
+overlayer thickness and on the overlayer material, resulting in an expanded
+range of structures with high perpendicular magnetic anisotropy. The origin of
+the SRT can be explained in terms of ab-initio calculations of the
+layer-resolved contributions to the magnetic anisotropy energy. Besides the
+changes in the SRT introduced by the capping, a quantitative enhancement of the
+magnetic anisotropy is identified. A detailed analysis of the interplay between
+strain and purely electronic effects allows us to identify the conditions that
+lead to a high perpendicular magnetic anisotropy in thin hcp Co films.",0804.4777v2
+2008-05-27,Gaussianity,"In this chapter we review the present status of the Gaussianity studies of
+the CMB anisotropies, including physical effects producing non-Gaussianity,
+methods to test it and observational constraints.",0805.4157v1
+2008-06-03,Mass distribution and orbital anisotropy of early-type galaxies: constraints from the Mass Plane,"Massive early-type galaxies are observed to lie on the Mass Plane (MP), a
+two-dimensional manifold in the space of effective radius R_e, projected mass
+M_p (measured via strong gravitational lensing) and projected velocity
+dispersion sigma within R_e/2. The MP is less `tilted' than the Fundamental
+Plane, and the two have comparable associated scatter. This means that
+c_e2=2*G*M_p/(R_e*sigma^2) is a nearly universal constant in the range
+sigma=175-400 km/s. This finding can be used to constrain the mass distribution
+and internal dynamics of early-type galaxies. We find that a relatively wide
+class of spherical galaxy models has values of c_e2 in the observed range,
+because c_e2 is not very strongly sensitive to the mass distribution and
+orbital anisotropy. If the total mass distribution is isothermal, a broad range
+of stellar luminosity profile and anisotropy is consistent with the
+observations, while NFW dark-matter halos require more fine tuning of the
+stellar mass fraction, luminosity profile and anisotropy. If future data can
+cover a broader range of masses, the MP could be seen to be tilted and the
+value of any such tilt would provide a discriminant between models for the
+total mass-density profile of the galaxies. [Abridged]",0806.0570v2
+2008-06-24,Superfluid Phase Stability of $^3$He in Axially Anisotropic Aerogel,"Measurements of superfluid $^3$He in 98% aerogel demonstrate the existence of
+a metastable \emph{A}-like phase and a stable \emph{B}-like phase. It has been
+suggested that the relative stability of these two phases is controlled by
+anisotropic quasiparticle scattering in the aerogel. Anisotropic scattering
+produced by axial compression of the aerogel has been predicted to stabilize
+the axial state of superfluid $^3$He. To explore this possiblity, we used
+transverse acoustic impedance to map out the phase diagram of superfluid $^3$He
+in a $\sim 98$% porous silica aerogel subjected to 17% axial compression. We
+have previously shown that axial anisotropy in aerogel leads to optical
+birefringence and that optical cross-polarization studies can be used to
+characterize such anisotropy. Consequently, we have performed optical
+cross-polarization experiments to verify the presence and uniformity of the
+axial anisotropy in our aerogel sample. We find that uniform axial anisotropy
+introduced by 17% compression does not stabilize the \emph{A}-like phase. We
+also find an increase in the supercooling of the \emph{A}-like phase at lower
+pressure, indicating a modification to \emph{B}-like phase nucleation in
+\emph{globally} anisotropic aerogels.",0806.3927v1
+2008-09-25,Two-component galaxies with flat rotation curve,"Dynamical properties of two-component galaxy models whose stellar density
+distribution is described by a gamma-model while the total density distribution
+has a pure r^(-2) profile, are presented. The orbital structure of the stellar
+component is described by Osipkov-Merritt anisotropy, while the dark matter
+halo is isotropic. After a description of minimum halo models, the positivity
+of the phase-space density (the model consistency) is investigated, and
+necessary and sufficient conditions for consistency are obtained analytically
+as a function of the stellar inner density slope gamma and anisotropy radius.
+The explicit phase-space distribution function is recovered for integer values
+of gamma, and it is shown that while models with gamma>4/17 are consistent when
+the anisotropy radius is larger than a critical value (dependent on gamma), the
+gamma=0 models are unphysical even in the fully isotropic case. The Jeans
+equations for the stellar component are then solved analytically; in addition,
+the projected velocity dispersion at the center and at large radii are also
+obtained analytically for generic values of the anisotropy radius, and it is
+found that they are given by remarkably simple expressions. The presented
+models, even though highly idealized, can be useful as starting point for more
+advanced modeling of the mass distribution of elliptical galaxies in studies
+combining stellar dynamics and gravitational lensing.",0809.4444v1
+2008-10-24,Detecting the Cosmic Dipole Anisotropy in Large-Scale Radio Surveys,"The detection of a dipole anisotropy in the sky distribution of sources in
+large-scale radio surveys can be used to constrain the magnitude and direction
+of our local motion with respect to an isotropically distributed extragalactic
+radio source population. Such a population is predicted to be present at
+cosmological redshifts in an isotropically expanding universe. The
+extragalactic radio source population is observed to have a median redshift of
+z ~ 1, a much later epoch than the cosmic microwave background (z ~ 1100). I
+consider the detectability of a velocity dipole anisotropy in radio surveys
+having a finite number of source counts. The statistical significance of a
+velocity dipole detection from radio source counts is also discussed in detail.
+I find that existing large-scale radio survey catalogs do not have a sufficient
+number of sources to detect the expected velocity dipole with statistical
+significance, even if survey masking and flux calibration complications can be
+completely eliminated (i.e., if both the surveys and observing instruments are
+perfect). However, a dipole anisotropy should be easily detectable in future
+radio surveys planned with next-generation radio facilities, such as the Low
+Frequency Array and the Square Kilometer Array; tight constraints on the dipole
+magnitude and direction should be possible if flux calibration problems can be
+sufficiently minimized or corrected and contamination from local sources
+eliminated.",0810.4520v1
+2009-02-20,Techniques to study cosmic ray anisotropies,"These lectures review some of the techniques used to analyze the arrival
+direction distribution of Cosmic Rays, and some relevant results on the field.",0902.3601v1
+2009-05-11,Cosmic ray electron anisotropies as a tool to discriminate between exotic and astrophysical sources,"Recent results from the PAMELA, ATIC, PPB BETS and Fermi collaborations
+extend the energy range in the electron flux measurement up to unexplored
+energies in the hundred GeVs range confirming the bump starting at about 10GeV
+already suggested by HEAT and AMS01 data . This bump can be explained by
+annihilating dark matter in the context of exotic physics, or by nearby
+astrophysical sources e.g. pulsars. In order to discriminate between competing
+models for primary positron production, the study of anisotropies
+,complementary to the spectrum determination, shows up as new tool to look for
+the origin of the lepton excess. In this letter we calculate the contribution
+to the electron flux given by the collection of all known gamma ray pulsars (as
+listed in the ATNF catalogue) and by annihilating dark matter both in case of a
+clumpy halo or in case the excess can be atributed to a nearby sizeable dark
+matter clump. We address the problem of the electron anisotropy in both
+scenarios and estimate the prospect that a small dipole anisotropy can be found
+by the Fermi observatory.",0905.1653v3
+2009-06-29,"Zero modes, energy gap, and edge states of anisotropic honeycomb lattice in a magnetic field","We present systematic study of zero modes and gaps by introducing effects of
+anisotropy of hopping integrals for a tight-binding model on the honeycomb
+lattice in a magnetic field. The condition for the existence of zero modes is
+analytically derived. From the condition, it is found that a tiny anisotropy
+for graphene is sufficient to open a gap around zero energy in a magnetic
+field. This gap behaves as a non-perturbative and exponential form as a
+function of the magnetic field. The non-analytic behavior with respect to the
+magnetic field can be understood as tunneling effects between energy levels
+around two Dirac zero modes appearing in the honeycomb lattice, and an explicit
+form of the gap around zero energy is obtained by the WKB method near the
+merging point of these Dirac zero modes. Effects of the anisotropy for the
+honeycomb lattices with boundaries are also studied. The condition for the
+existence of zero energy edge states in a magnetic field is analytically
+derived. On the basis of the condition, it is recognized that anisotropy of the
+hopping integrals induces abrupt changes of the number of zero energy edge
+states, which depend on the shapes of the edges sensitively.",0906.5027v2
+2009-07-09,Ground states of anisotropic antiferromagnets with single ion and cubic anisotropy,"Anisotropic antiferromagnets in an external magnetic field show a rich
+variety of different ground states meeting in transition lines and
+multicritical points. We study the dependence of the ground states of these
+systems in the three dimensional space on physical parameters as exchange,
+single ion and cubic anisotropy.
+  One identifies four different ground states: the paramagnetic (PM), the
+antiferromagnetic (AF), the spin flop (SF) and the biconical (BC) ground state.
+In the case of absence of a cubic anisotropy the transition lines separating
+the different ground states can be calculated analytically, otherwise they have
+to be calculated numerically. We also considered the behavior of the staggered
+magnetization which characterizes the different ground states. From its
+behavior the order of the transition from one state to the other is determined.
+But also the order of the transition changes along the transition lines when
+including the cubic anisotropy, especially at the reeentrant region where a
+transition from SF to BC and back to SF by increasing the external field $H$
+occurs. Multicritical points are founded which are assumed to be tricritical or
+critical endpoints. The results obtained may be relevant for other systems
+since the antiferromagnetic model can be mapped to a lattice gas model where
+the biconical ground state is interpreted as supersolid phase. Recent
+renormalization group calculations show that such a phase would indicate the
+existence of a tetracritical point.",0907.1480v1
+2009-09-05,The sidereal anisotropy of multi-TeV cosmic rays in an expanding Local Interstellar Cloud,"The sidereal anisotropy of galactic cosmic ray (GCR) intensity observed with
+the Tibet Air Shower (AS) experiment still awaits theoretical interpretation.
+The observed global feature of the anisotropy is well reproduced by a
+superposition of the bi-directional and uni-directional flows (BDF and UDF,
+respectively) of GCRs. If the orientation of the deduced BDF represents the
+orientation of the local interstellar magnetic field (LISMF), as indicated by
+best-fitting a model to the data, the UDF deviating from the BDF orientation
+implies a significant contribution from the streaming perpendicular to the
+LISMF. This perpendicular streaming is probably due to the drift anisotropy,
+because the contribution from the perpendicular diffusion is expected to be
+much smaller than the drift effect. The large amplitude deduced for the UDF
+indicates a large spatial gradient of the GCR density. We suggest that such a
+density gradient can be expected at the heliosphere sitting close to the
+boundary of the Local Interstellar Cloud (LIC), if the LIC is expanding. The
+spatial distribution of GCR density in the LIC reaches a stationary state
+because of the balance between the inward cross-field diffusion and the
+adiabatic cooling due to the expansion. We derive the steady-state distribution
+of GCR density in the LIC based on radial transport of GCRs in a spherical LIC
+expanding at a constant rate. By comparing the expected gradient with the
+observation by Tibet experiment, we estimate the perpendicular diffusion
+coefficient of multi-TeV GCRs in the local interstellar space.",0909.1029v1
+2009-10-30,Resonant x-ray scattering in 3d-transition-metal oxides: Anisotropy and charge orderings,"The structural, magnetic and electronic properties of transition metal oxides
+reflect in atomic charge, spin and orbital degrees of freedom. Resonant x-ray
+scattering (RXS) allows us to perform an accurate investigation of all these
+electronic degrees. RXS combines high-Q resolution x-ray diffraction with the
+properties of the resonance providing information similar to that obtained by
+atomic spectroscopy (element selectivity and a large enhancement of scattering
+amplitude for this particular element and sensitivity to the symmetry of the
+electronic levels through the multipole electric transitions). Since electronic
+states are coupled to the local symmetry, RXS reveals the occurrence of
+symmetry breaking effects such as lattice distortions, onset of electronic
+orbital ordering or ordering of electronic charge distributions. We shall
+discuss the strength of RXS at the K absorption edge of 3d transition-metal
+oxides by describing various applications in the observation of local
+anisotropy and charge disproportionation. Examples of these resonant effects
+are (I) charge ordering transitions in manganites, Fe3O4 and ferrites and (II)
+forbidden reflections and anisotropy in Mn3+ perovskites, spinel ferrites and
+cobalt oxides. In all the studied cases, the electronic (charge and/or
+anisotropy) orderings are determined by the structural distortions.",0910.5789v1
+2009-11-05,Layer World: Living on a layer in 5D SU(3),"We suggest another approach to five-dimensional non-isotropic gauge theory.
+Using non-perturbative technique we show that already modest interaction
+anisotropy confines heavy bound states to four-dimensional layers, while free
+quarks propagate with almost no penalty into the fifth dimension.",0911.1071v1
+2009-11-13,Landau hydrodynamic solution for non-central heavy ion collisions,"The manuscript presents generalization of the Landau hydrodynamic solution
+for multiparticle production applied for non-central relativistic heavy ion
+collisions. Obtained solution enables to calculate anisotropy parameter $v_2$
+for different rapidities with respect to the initial conditions for
+hydrodynamics.",0911.2677v1
+2009-12-12,The fundamental spherically symmetric fluid model,"It is shown that an effective anisotropic spherically symmetric fluid model
+with heat flow can absorb the addition to a perfect fluid of pressure
+anisotropy, heat flow, bulk and shear viscosity, electric field and null fluid.",0912.2447v1
+2010-05-07,Vortex Dynamics in Anisotropic Traps,"We investigate the dynamics of linear vortex lattices in anisotropic traps in
+two-dimensions and show that the interplay between the rotation and the
+anisotropy leads to a rich but highly regular dynamics.",1005.1262v1
+2010-05-25,"Structural, static and dynamic magnetic properties of CoMnGe thin films on a sapphire a-plane substrate","Magnetic properties of CoMnGe thin films of different thicknesses (13, 34,
+55, 83, 100 and 200 nm), grown by RF sputtering at 400{\deg}C on single crystal
+sapphire substrates, were studied using vibrating sample magnetometry (VSM) and
+conventional or micro-strip line (MS) ferromagnetic resonance (FMR). Their
+behavior is described assuming a magnetic energy density showing twofold and
+fourfold in-plane anisotropies with some misalignment between their principal
+directions. For all the samples, the easy axis of the fourfold anisotropy is
+parallel to the c-axis of the substrate while the direction of the twofold
+anisotropy easy axis varies from sample to sample and seems to be strongly
+influenced by the growth conditions. Its direction is most probably monitored
+by the slight unavoidable angle of miscut the Al2O3 substrate. The twofold
+in-plane anisotropy field is almost temperature independent, in contrast with
+the fourfold field which is a decreasing function of the temperature. Finally,
+we study the frequency dependence of the observed line-width of the resonant
+mode and we conclude to a typical Gilbert damping constant of 0.0065 for the
+55-nm-thick film.",1005.4595v3
+2010-07-19,Gauge field back-reaction in Born Infeld cosmologies,"In this paper, we investigate the back-reaction of $U(1)$ gauge fields into a
+class of inflationary settings. To be more precise, we employ a Bianchi-I
+geometry (taken as an anisotropic perturbation of a flat FRW model) within two
+types of Born-Infeld theories. Firstly we consider pure Born-Infeld
+electromagnetism. For either a constant or a $b(\phi)$ coupling, inflationary
+trajectories are modified but anisotropies increase; In particular, for the
+former coupling we find that a quadratic inflaton potential, within a constant
+ratio for the scalar and gauge energy densities, does not induce sufficient
+inflation, while in the latter the back-reaction in the cosmology determines
+(from the tensor-scalar ratio) a narrow range where inflation can occur. A
+Dirac-Born-Infeld framework is afterwards analysed in both non-relativistic and
+relativistic regimes. In the former, for different cases of the coupling
+(richer with respect to mere BI setups) between scalar and gauge sectors, we
+find that inflationary trajectories are modified, with anisotropy increasing or
+decreasing. In particular, a tachyonic solution is studied, allowing for a non
+standard ratio between scalar and gauge matter densities, enhancing sufficient
+inflation, but with the anisotropy increasing. For the relativistic limit,
+inflationary trajectories are also modified and anisotropies increase faster
+than in the non-relativistic limit. Finally we discuss how magnetic seed fields
+could evolve in these settings.",1007.3299v2
+2010-11-02,Electron transport and anisotropy of the upper critical magnetic field in a Ba0.68K0.32Fe2As2 single crystals,"Early work on the iron-arsenide compounds supported the view, that a reduced
+dimensionality might be a necessary prerequisite for high-Tc superconductivity.
+Later, however, it was found that the zero-temperature upper critical magnetic
+field, Hc2(0), for the 122 iron pnictides is in fact rather isotropic. Here, we
+report measurements of the temperature dependence of the electrical
+resistivity, \Gamma(T), in Ba0.5K0.5Fe2As2 and Ba0.68K0.32Fe2As2 single
+crystals in zero magnetic field and for Ba0.68K0.32Fe2As2 as well in static and
+pulsed magnetic fields up to 60 T. We find that the resistivity of both
+compounds in zero field is well described by an exponential term due to
+inter-sheet umklapp electron-phonon scattering between light electrons around
+the M point to heavy hole sheets at the \Gamma point in reciprocal space. From
+our data, we construct an H-T phase diagram for the inter-plane (H || c) and
+in-plane (H || ab) directions for Ba0.68K0.32Fe2As2. Contrary to published data
+for underdoped 122 FeAs compounds, we find that Hc2(T) is in fact anisotropic
+in optimally doped samples down to low temperatures. The anisotropy parameter,
+{\gamma} = Habc2/Hcc2, is about 2.2 at Tc. For both field orientations we find
+a concave curvature of the Hc2 lines with decreasing anisotropy and saturation
+towards lower temperature. Taking into account Pauli spin paramagnetism we
+perfectly can describe Hc2(T) and its anisotropy.",1011.0698v1
+2010-11-12,Age- and time-varying proportional hazards models for employment discrimination,"We use a discrete-time proportional hazards model of time to involuntary
+employment termination. This model enables us to examine both the continuous
+effect of the age of an employee and whether that effect has varied over time,
+generalizing earlier work [Kadane and Woodworth J. Bus. Econom. Statist. 22
+(2004) 182--193]. We model the log hazard surface (over age and time) as a
+thin-plate spline, a Bayesian smoothness-prior implementation of penalized
+likelihood methods of surface-fitting [Wahba (1990) Spline Models for
+Observational Data. SIAM]. The nonlinear component of the surface has only two
+parameters, smoothness and anisotropy. The first, a scale parameter, governs
+the overall smoothness of the surface, and the second, anisotropy, controls the
+relative smoothness over time and over age. For any fixed value of the
+anisotropy parameter, the prior is equivalent to a Gaussian process with linear
+drift over the time--age plane with easily computed eigenvectors and
+eigenvalues that depend only on the configuration of data in the time--age
+plane and the anisotropy parameter. This model has application to legal cases
+in which a company is charged with disproportionately disadvantaging older
+workers when deciding whom to terminate. We illustrate the application of the
+modeling approach using data from an actual discrimination case.",1011.2851v1
+2010-11-25,Effects of magnetic field and transverse anisotropy on full counting statistics in single-molecule magnet,"We have theoretically studied the full counting statistics of electron
+transport through a single-molecule magnet (SMM) with an arbitrary angle
+between the applied magnetic field and the SMM's easy axis above the sequential
+tunneling threshold, since the angle $\theta$ cannot be controlled in
+present-day SMM experiments. In the absence of the small transverse anisotropy,
+when the coupling of the SMM with the incident-electrode is stronger than that
+with the outgoing-electrode, i.e., $\Gamma_{L}/\Gamma_{R}\gg1$, the maximum
+peak of shot noise first increases and then decreases with increasing $\theta$
+from 0 to $0.5\pi$. In particular, the shot noise can reach up to
+super-Poissonian value from sub-Poissonian value when considering the small
+transverse anisotropy. For $\Gamma_{L}/\Gamma_{R}\ll1$, the maximum peaks of
+the shot noise and skewness can be reduced from a super-Poissonian to a
+sub-Poissonian value with increasing $\theta$ from 0 to $0.5\pi$; the
+super-Poissonian behavior of the skewness is more sensitive to the small
+$\theta$ than shot noise, which is suppressed when taking into account the
+small transverse anisotropy. These characteristics of shot noise can be
+qualitatively attributed to the competition between the fast and slow transport
+channels. The predictions regarding of the $\theta$-dependence of high order
+current cumulants are very interesting for a better understanding electron
+transport through SMM, and will allow for experimental tests in the near
+future.",1011.5546v2
+2010-12-17,Phenomenology of magnetically active superconductors,"The thermodynamical phenomenological theory of magnetically active
+superconducting materials and magnetic-superconducting heterostructures is
+presented. The materials may exhibit arbitrarily strong anisotropy, parametric
+or structural. Exact anisotropic similarity transformations are found for both
+the continuum and layered hybrid systems.",1012.3869v1
+2010-12-23,Ellipsoidal anisotropies in linear elasticity Extension of Saint Venant's work to phenomenological modelling of materials,"Several families of elastic anisotropies were introduced by Saint Venant
+(1863) for which the polar diagram of elastic parameters in different
+directions of the material (indicator surface) are ellipsoidal. These families
+recover a large variety of models introduced in recent years for damaged
+materials or as effective modulus of heterogeneous materials. On the other
+hand, ellipsoidal anisotropy has been used as a guideline in phenomenological
+modeling of materials. A question that then naturally arises is to know in
+which conditions the assumption that some indicator surfaces are ellipsoidal
+allows one to entirely determine the elastic constants. This question has not
+been rigorously studied in the literature. In this paper, first several basic
+classes of ellipsoidal anisotropy are presented. Then the problem of
+determination of the elastic parameters from indicator surfaces is discussed in
+several basic cases that can occur in phenomenological modelling. Finally the
+compatibility between the assumption of ellipsoidal form for different
+indicator surfaces is discussed and in particular, it is shown that if the
+indicator surfaces of the fourth root of E(n) and of 1/c(n) where E(n) and c(n)
+are respectively the Young's modulus and the elastic coefficient in the
+direction n) are ellipsoidal, then the two ellipsoids have necessarily the same
+principal axes and the material in this case is orthotropic.",1012.5148v1
+2010-12-23,Deep Core muon neutrino rate and anisotropy by mixing and CPT violation,"Neutrinos are allowed to mix and to oscillate among their flavor. Muon and
+tau in particular oscillate at largest values.Last Minos experiment claimed
+possible difference among their matter and anti-matter masses, leading to a
+first violation of the most believed CPT symmetry.Isotropically born
+atmospheric muon neutrino at 20-80 GeV, while up-going, they might be partially
+suppressed by mixing in analogy to historical SuperKamiokande muon neutrino
+disappearance into tau, leading to large scale anisotropy signals. Here we show
+an independent muon rate foreseen in Deep Core based on observed SK signals
+extrapolated to DeepCore mass and its surrounding. Our rate prediction
+partially differ from previous ones. The neutrino muon disappearance into tau
+is leading to an anisotropy in vertical up-going muon track: in particular
+along channel 3-5 we expect a huge rate (tens of thousand of events) of neutral
+current events, charged current electron and inclined crossing muons. Moreover
+at channel 6-9 we expect a severe suppression of the rate due to muon
+disappearance (in CPT conserved frame). Such an anisotropy might be partially
+tested by more than one string detection at E> 45 GeV energy. A CPT violation
+may induce a more remarkable suppression of vertical up-going tracks because of
+larger anti-neutrino muon reduction for E> 35 GeV.",1012.5271v1
+2010-12-31,In-plane anisotropy of electrical resistivity in the strain-detwinned SrFe2As2,"Intrinsic, in-plane anisotropy of electrical resistivity was studied on
+mechanically detwinned single crystals of SrFe$_2$As$_2$ above and below the
+temperature of the coupled structural/magnetic transition, $T_{\textrm{TO}}$.
+Resistivity is smaller for electrical current flow along the orthorhombic $a_o$
+direction (direction of antiferromagnetically alternating magnetic moments) and
+is larger for transport along the $b_o$ direction (direction of ferromagnetic
+chains), which is similar to CaFe$_2$As$_2$ and BaFe$_2$As$_2$ compounds. A
+strongly first order structural transition in SrFe$_2$As$_2$ was confirmed by
+high-energy x-ray measurements, with the transition temperature, and character
+unaffected by moderate strain. For small strain levels, which are just
+sufficient to detwin the sample, we find a negligible effect on the resistivity
+above $T_{\textrm{TO}}$. With the increase of strain, the resistivity
+anisotropy starts to develop above $T_{\textrm{TO}}$, clearly showing the
+relation of anisotropy to an anomalously strong response to strain. Our study
+suggests that electronic nematicity cannot be observed in the FeAs based
+compounds in which the structural transition is strongly first order.",1101.0274v1
+2011-01-14,How to distinguish the Haldane/Large-D state and the intermediate-D state in an S=2 quantum spin chain with the XXZ and on-site anisotropies,"We numerically investigate the ground-state phase diagram of an S=2 quantum
+spin chain with the $XXZ$ and on-site anisotropies described by ${\mathcal
+H}=\sum_j (S_j^x S_{j+1}^x+S_j^y S_{j+1}^y+\Delta S_j^z S_{j+1}^z) + D \sum_j
+(S_j^z)^2$, where $\Delta$ denotes the XXZ anisotropy parameter of the
+nearest-neighbor interactions and $D$ the on-site anisotropy parameter. We
+restrict ourselves to the $\Delta>0$ and $D>0$ case for simplicity. Our main
+purpose is to obtain the definite conclusion whether there exists or not the
+intermediate-$D$ (ID) phase, which was proposed by Oshikawa in 1992 and has
+been believed to be absent since the DMRG studies in the latter half of 1990's.
+In the phase diagram with $\Delta>0$ and $D>0$ there appear the XY state, the
+Haldane state, the ID state, the large-$D$ (LD) state and the N\'eel state. In
+the analysis of the numerical data it is important to distinguish three gapped
+states; the Haldane state, the ID state and the LD state. We give a physical
+and intuitive explanation for our level spectroscopy method how to distinguish
+these three phases.",1101.2799v2
+2011-01-20,"Ultra-thin SWNTs Films with Tunable, Anisotropic Transport Properties","Directional transport properties at the nanoscale remain a challenge
+primarily due to issues associated with control over the underlying anisotropy
+and scalability to macroscopic scales. In this letter, we develop a facile
+approach based on template-guided fluidic assembly of high mobility building
+blocks - single walled carbon nanotubes (SWNTs) - to fabricate ultra-thin and
+anisotropic SWNT films. A major advancement is the complete control over the
+anisotropy in the assembled nanostructure, realized by three-dimensional
+engineering of dip-coated SWNT thin films into alternating hydrophilic and
+hydrophobic micro-line patterns with prescribed intra/inter-line widths and
+line thicknesses. Variations in the contact line profile results in an
+evaporation-controlled assembly mechanism that leads to the formation of an
+alternating, and more importantly, contiguous SWNT network. Evidently, the
+nanoscopic thickness modulations are direct reflections of the substrate
+geometry and chemistry. The nanostructured film exhibits significant anisotropy
+in their electrical and thermal transport properties as well as optical
+transparency, as revealed by characterization studies. The direct interplay
+between the anisotropy and the 3D micro-line patterns of the substrate combined
+with the wafer-level scalability of the fluidic assembly allows us to tune the
+transport properties for a host of nanoelectronic applications.",1101.3805v1
+2011-04-20,Oscillating Bianchi IX Universe in Horava-Lifshitz Gravity,"We study a vacuum Bianchi IX universe in the context of Ho\v{r}ava-Lifshitz
+(HL) gravity. In particular, we focus on the classical dynamics of the universe
+and analyze how anisotropy changes the history of the universe. For small
+anisotropy, we find an oscillating universe as well as a bounce universe just
+as the case of the Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime.
+However, if the initial anisotropy is large, we find the universe which ends up
+with a big crunch after oscillations if a cosmological constant $\Lambda$ is
+zero or negative. For $\Lambda>0$, we find a variety of histories of the
+universe, that is de Sitter expanding universe after oscillations in addition
+to the oscillating solution and the previous big crunch solution. This fate of
+the universe shows sensitive dependence of initial conditions, which is one of
+the typical properties of a chaotic system. If the initial anisotropy is near
+the upper bound, we find the universe starting from a big bang and ending up
+with a big crunch for $\Lambda\leq 0$, while de Sitter expanding universe
+starting from a big bang for $\Lambda>0$.",1104.3978v2
+2011-05-25,Properties of Turbulence in the Very Local Interstellar Clouds,"We have investigated the degree to which turbulence in the Very Local
+Interstellar Clouds resembles the highly-studied turbulence in the solar corona
+and the solar wind. The turbulence diagnostics for the Local Clouds are the
+absorption line widths measured along 32 lines of sight to nearby stars,
+yielding measurements for 53 absorption components (Redfield and Linsky 2004).
+We have tested whether the Local Cloud turbulence has the following properties
+of turbulence in the solar corona or the solar wind: (a) velocity fluctuations
+mainly perpendicular to the average magnetic field, (b) a temperature
+anisotropy in the sense that the perpendicular temperature is larger than the
+parallel temperature (or at least enhanced relative to expectation), and (c) an
+ion temperature which is dependent on the ion Larmor radius, in the sense that
+more massive ions have higher temperatures. Our analysis of the data does not
+show compelling evidence for any of these properties in Local Cloud turbulence,
+indicating possible differences with heliospheric plasmas. In the case of
+anisotropy of velocity fluctuations, although the expected observational
+signature is not seen, we cannot exclude the possibility of relatively high
+degrees of anisotropy (anisotropy parameter $\epsilon \sim 0.50 - 0.70$), if
+some other process in the the Local Clouds is causing variations in the
+turbulent line width from one line of sight to another. We briefly consider
+possible reasons for differences between coronal and solar wind turbulence and
+that in the Local Clouds.",1105.5077v1
+2011-05-29,Conductance anisotropy and linear magnetoresistance in La2-xSrxCuO4 thin films,"We have performed a detailed study of conductance anisotropy and
+magnetoresistance (MR) of La2-xSrxCuO4 (LSCO) thin films (0.10 < x < 0.25).
+These two observables are promising for the detection of stripes. Subtle
+features of the conductance anisotropy are revealed by measuring the transverse
+resistance Rxy in zero magnetic field. It is demonstrated that the sign of Rxy
+depends on the orientation of the LSCO Hall bar with respect to the terrace
+structure of the substrate. Unit-cell-high substrate step edges must therefore
+be a dominant nucleation source for antiphase boundaries during film growth. We
+show that the measurement of Rxy is sensitive enough to detect the
+cubic-tetragonal phase transition of the SrTiO3(100) (STO) substrate at 105 K.
+The MR of LSCO thin films shows for 0.10 < x < 0.25 a non-monotonic temperature
+dependence, resulting from the onset of a linear term in the MR above 90 K. We
+show that the linear MR scales with the absolute Hall resistivity, with the
+constant of proportionality independent of temperature. Such scaling suggests
+that the linear MR originates from current distortions induced by structural or
+electronic inhomogeneities. The possible role of stripes for both the MR and
+the conductance anisotropy is discussed throughout the paper.",1105.6090v1
+2011-06-24,Unprecedented anisotropic metallic state in BaFe2As2 revealed by optical spectroscopy,"An ordered phase showing remarkable electronic anisotropy in proximity to the
+superconducting phase is now a hot issue in the field of
+high-transition-temperature superconductivity. As in the case of copper oxides,
+superconductivity in iron arsenides competes or coexists with such an ordered
+phase. Undoped and underdoped iron arsenides have a magnetostructural ordered
+phase exhibiting stripe-like antiferromagnetic spin order accompanied by an
+orthorhombic lattice distortion; both the spin order and lattice distortion
+break the tetragonal symmetry of crystals of these compounds. In this ordered
+state, anisotropy of in-plane electrical resistivity is anomalous and difficult
+to attribute simply to the spin order and/or the lattice distortion. Here, we
+present the anisotropic optical spectra measured on detwinned BaFe2As2 crystals
+with light polarization parallel to the Fe planes. Pronounced anisotropy is
+observed in the spectra, persisting up to an unexpectedly high photon energy of
+about 2 eV. Such anisotropy arises from an anisotropic energy gap opening below
+and slightly above the onset of the order. Detailed analysis of the optical
+spectra reveals an unprecedented electronic state in the ordered phase.",1106.4967v1
+2011-06-24,Note on a class of anisotropic Einstein metrics,"A class of anisotropic Einstein metrics is presented. These metrics are axial
+symmetric and contains an anisotropy parameter $\alpha$, which is identified as
+the amplitude of the proper acceleration of the origin, thus explaining the
+ellipsoid shape of the horizon.",1106.5027v1
+2011-07-04,Anisotropic in-plane optical conductivity in detwinned Ba(Fe1-xCox)2As2,"We study the anisotropic in-plane optical conductivity of detwinned
+Ba(Fe1-xCox)2As2 single crystals for x=0, 2.5% and 4.5% in a broad energy range
+(3 meV-5 eV) across their structural and magnetic transitions. For temperatures
+below the Neel transition, the topology of the reconstructed Fermi surface,
+combined with the distinct behavior of the scattering rates, determines the
+anisotropy of the low frequency optical response. For the itinerant charge
+carriers, we are able to disentangle the evolution of the Drude weights and
+scattering rates and to observe their enhancement along the orthorhombic
+antiferromagnetic a-axis with respect to the ferromagnetic b-axis. For
+temperatures above Ts, uniaxial stress leads to a finite in-plane anisotropy.
+The anisotropy of the optical conductivity, leading to a significant dichroism,
+extends to high frequencies in the mid- and near-infrared regions. The
+temperature dependence of the dichroism at all dopings scales with the
+anisotropy ratio of the dc conductivity, suggesting the electronic nature of
+the structural transition. Our findings bear testimony to a large nematic
+susceptibility that couples very effectively to the uniaxial lattice strain. In
+order to clarify the subtle interplay of magnetism and Fermi surface topology
+we compare our results with theoretical calculations obtained from density
+functional theory within the full-potential linear augmented plane-wave method.",1107.0670v1
+2011-09-07,Improved Models for Cosmic Infrared Background Anisotropies: New Constraints on the IR Galaxy Population,"The power spectrum of cosmic infrared background (CIB) anisotropies is
+sensitive to the connection between star formation and dark matter halos over
+the entire cosmic star formation history. Here we develop a model that
+associates star-forming galaxies with dark matter halos and their subhalos. The
+model is based on a parameterized relation between the dust-processed infrared
+luminosity and (sub)halo mass. By adjusting 3 free parameters, we attempt to
+simultaneously fit the 4 frequency bands of the Planck measurement of the CIB
+anisotropy power spectrum. To fit the data, we find that the star-formation
+efficiency must peak on a halo mass scale of ~ 5x10^12 solar mass and the
+infrared luminosity per unit mass must increase rapidly with redshift. By
+comparing our predictions with a well-calibrated phenomenological model for
+shot noise, and with a direct observation of source counts, we show that the
+mean duty cycle of the underlying infrared sources must be near unity,
+indicating that the CIB is dominated by long-lived quiescent star formation,
+rather than intermittent short ""star bursts"". Despite the improved flexibility
+of our model, the best simultaneous fit to all four Planck channels remains
+relatively poor. We discuss possible further extensions to alleviate the
+remaining tension with the data. Our model presents a theoretical framework for
+a future joint analysis of both background anisotropy and source count
+measurements.",1109.1522v1
+2011-09-22,Cosmic String constraints from WMAP and the South Pole Telescope,"The predictions of the inflationary LCDM paradigm match today's
+high-precision measurements of the cosmic microwave background anisotropy
+extremely well. The same data put tight limits on other sources of anisotropy.
+Cosmic strings are a particularly interesting alternate source to constrain.
+Strings are topological defects, remnants of inflationary-era physics that
+persist after the big bang. They are formed in a variety of models of
+inflation, including string theory models such as brane inflation. We assume a
+""Nambu-Goto"" model for strings, approximated by a collection of unconnected
+segments with zero width, and show that measurements of temperature anisotropy
+by the South Pole Telescope break a parameter degeneracy in the WMAP data,
+permitting us to place a strong upper limit on the possible string contribution
+to the CMB anisotropy: the power sourced by zero-width strings must be <1.75%
+(95% CL) of the total or the string tension Gmu <1.7x10^{-7}. These limits
+imply that the best hope for detecting strings in the CMB will come from B-mode
+polarization measurements at arcminute scales rather than the degree scale
+measurements pursued for gravitational wave detection.",1109.4947v2
+2011-10-05,Anisotropies in the diffuse gamma-ray background measured by Fermi LAT,"The small angular scale fluctuations of the (on large scale) isotropic
+gamma-ray background (IGRB) carry information about the presence of unresolved
+source classes. A guaranteed contribution to the IGRB is expected from the
+unresolved gamma-ray AGN while other extragalactic sources, Galactic gamma-ray
+source populations and dark matter Galactic and extragalactic structures (and
+sub-structures) are candidate contributors. The IGRB was measured with
+unprecedented precision by the Large Area Telescope (LAT) on-board of the Fermi
+gamma-ray observatory, and these data were used for measuring the IGRB angular
+power spectrum (APS). Detailed Monte Carlo simulations of Fermi-LAT all-sky
+observations were performed to provide a reference against which to compare the
+results obtained for the real data set. The Monte Carlo simulations are also a
+method for performing those detailed studies of the APS contributions of single
+source populations, which are required in order to identify the actual IGRB
+contributors. We present preliminary results of an anisotropy search in the
+IGRB. At angular scales <2deg (e.g. above multipole 155), angular power above
+the photon noise level is detected, at energies between 1 and 10 GeV in each
+energy bin, with statistical significance between 7.2 and 4.1 sigmas. The
+energy not dependence of the fluctuation anisotropy is pointing to the presence
+of one or more unclustered source populations, while the energy dependence of
+the intensity anisotropy is consistent with source populations having average
+photon index 2.40\pm0.07.",1110.1047v2
+2011-10-11,Bianchi type II models in the presence of perfect fluid and anisotropic dark energy,"Spatially homogeneous but totally anisotropic and non-flat Bianchi type II
+cosmological model has been studied in general relativity in the presence of
+two minimally interacting fluids; a perfect fluid as the matter fluid and a
+hypothetical anisotropic fluid as the dark energy fluid. The Einstein's field
+equations have been solved by applying two kinematical ans\""{a}tze: we have
+assumed the variation law for the mean Hubble parameter that yields a constant
+value of deceleration parameter, and one of the components of the shear tensor
+has been considered proportional to the mean Hubble parameter. We have
+particularly dwelled on the accelerating models with non-divergent expansion
+anisotropy as the Universe evolves. Yielding anisotropic pressure, the fluid we
+consider in the context of dark energy, can produce results that can be
+produced in the presence of isotropic fluid in accordance with the \Lambda CDM
+cosmology. However, the derived model gives additional opportunities by being
+able to allow kinematics that cannot be produced in the presence of fluids that
+yield only isotropic pressure. We have obtained well behaving cases where the
+anisotropy of the expansion and the anisotropy of the fluid converge to finite
+values (include zero) in the late Universe. We have also showed that although
+the metric we consider is totally anisotropic, the anisotropy of the dark
+energy is constrained to be axially symmetric, as long as the overall energy
+momentum tensor possesses zero shear stress.",1110.2408v2
+2011-10-12,High-precision CTE measurement of hybrid C/SiC composite for cryogenic space telescopes,"This paper presents highly precise measurements of thermal expansion of a
+""hybrid"" carbon-fiber reinforced silicon carbide composite,
+HB-Cesic\textregistered - a trademark of ECM, in the temperature region of
+\sim310-10K. Whilst C/SiC composites have been considered to be promising for
+the mirrors and other structures of space-borne cryogenic telescopes, the
+anisotropic thermal expansion has been a potential disadvantage of this
+material. HB-Cesic\textregistered is a newly developed composite using a
+mixture of different types of chopped, short carbon-fiber, in which one of the
+important aims of the development was to reduce the anisotropy. The
+measurements indicate that the anisotropy was much reduced down to 4% as a
+result of hybridization. The thermal expansion data obtained are presented as
+functions of temperature using eighth-order polynomials separately for the
+horizontal (XY-) and vertical (Z-) directions of the fabrication process. The
+average CTEs and their dispersion (1{\sigma}) in the range 293-10K derived from
+the data for the XY- and Z-directions were 0.805$\pm$0.003\times10$^{-6}$
+K$^{-1}$ and 0.837\pm0.001\times10$^{-6}$ K$^{-1}$, respectively. The absolute
+accuracy and the reproducibility of the present measurements are suggested to
+be better than 0.01\times10$^{-6}$ K$^{-1}$ and 0.001\times(10)^{-6} K^{-1},
+respectively. The residual anisotropy of the thermal expansion was consistent
+with our previous speculation regarding carbon-fiber, in which the residual
+anisotropy tended to lie mainly in the horizontal plane.",1110.2620v1
+2012-01-31,Local 2D Particle-in-cell simulations of the collisionless MRI,"The magnetorotational instability (MRI) is a crucial mechanism of angular
+momentum transport in a variety of astrophysical accretion disks. In systems
+accreting at well below the Eddington rate, such as the central black hole in
+the Milky Way (Sgr A*), the rate of Coulomb collisions between particles is
+very small, making the disk evolve essentially as a collisionless plasma. We
+present a nonlinear study of the collisionless MRI using first-principles
+particle-in-cell (PIC) plasma simulations. In this initial study we focus on
+local two-dimensional (axisymmetric) simulations, deferring more realistic
+three-dimensional simulations to future work. For simulations with net vertical
+magnetic flux, the MRI continuously amplifies the magnetic field until the
+Alfv\'en velocity, v_A, is comparable to the speed of light, c (independent of
+the initial value of v_A/c). This is consistent with the lack of saturation of
+MRI channel modes in analogous axisymmetric MHD simulations. The amplification
+of the magnetic field by the MRI generates a significant pressure anisotropy in
+the plasma (with the perpendicular pressure being larger than the parallel
+pressure). We find that this pressure anisotropy in turn excites mirror modes
+and that the volume averaged pressure anisotropy remains near the threshold for
+mirror mode excitation. Particle energization is due to both reconnection and
+viscous heating associated with the pressure anisotropy. Reconnection produces
+a distinctive power-law component in the energy distribution function of the
+particles, indicating the likelihood of non-thermal ion and electron
+acceleration in collisionless accretion disks. This has important implications
+for interpreting the observed emission -- from the radio to the gamma-rays --
+of systems such as Sgr A*.",1201.6407v1
+2012-02-20,Statistical anisotropy of CMB as a probe of conformal rolling scenario,"Search for the statistical anisotropy in the CMB data is a powerful tool for
+constraining models of the early Universe. In this paper we focus on the
+recently proposed cosmological scenario with conformal rolling. We consider two
+sub-scenarios, one of which involves a long intermediate stage between
+conformal rolling and conventional hot epoch. Primordial scalar perturbations
+generated within these sub-scenarios have different direction-dependent power
+spectra, both characterized by a single parameter h^2. We search for the
+signatures of this anisotropy in the seven-year WMAP data using quadratic
+maximum likelihood method, first applied for similar purposes by Hanson and
+Lewis. We confirm the large quadrupole anisotropy detected in V and W bands,
+which has been argued to originate from systematic effects rather than from
+cosmology. We construct an estimator for the parameter h^2. In the case of the
+sub-scenario with the intermediate stage we set an upper limit h^2 < 0.045 at
+the 95% confidence level. The constraint on h^2 is much weaker in the case of
+another sub-scenario, where the intermediate stage is absent.",1202.4357v3
+2012-03-21,Implication of the lopsided growth for the viscosity of Earth's inner core,"Two main seismic features characterize the Earth's inner core: a North-South
+polar anisotropy and an East-West asymmetry of P-wave velocity and attenuation.
+Anisotropy is expected if shear deformation is induced by convective motions.
+Translation has recently been put forward as an important mode of convection of
+the inner core. Combined with a simple diffusive grain growth model, this
+mechanism is able to explain the observed seismic asymmetry, but not the bulk
+anisotropy. The source of anisotropy has therefore to be sought in the shear
+motions caused by higher modes of convection. Using a hybrid finite-difference
+spherical harmonics Navier-Stokes solver, we investigate the interplay between
+translation and convection in a 3D spherical model with permeable boundary
+conditions at the inner core boundary. Three parameters act independently:
+viscosity, internal heating and convection velocity in the outer core. Our
+numerical simulations show the dominance of pure translation for viscosities of
+the inner core higher than $10^{20}$ Pas. Translation is almost completely
+hampered by convective motions for viscosities lower than $10^{18}$ Pas.
+Between these values, translation and convection develop, but convective
+downwellings are restricted to the coldest hemisphere where crystallization
+occurs. On the opposite side, shear is almost absent, thereby allowing grain
+growth. We propose that the coexistence of translation and convection observed
+in our numerical models leads to a seismic asymmetry but localizes deformation
+only in one hemisphere.",1203.4708v1
+2012-03-30,"Transport properties, upper critical field and anisotropy of Ba(Fe$_{0.75}$Ru$_{0.25}$)$_2$As$_2$ single crystals","The temperature and angle dependent resistivity of
+Ba(Fe$_{0.75}$Ru$_{0.25}$)$_2$As$_2$ single crystals were measured in magnetic
+fields up to 14 T. The temperature dependent resistivity with the magnetic
+field aligned parallel to c-axis and ab-planes allow us to derive the slope of
+d$H_{c2}^{ab}/dT$ and d$H_{c2}^c/dT$ near $T_c$ yielding an anisotropy ratio
+$\Gamma=dH_{c2}^{ab}/dT/dH_{c2}^c/dT \approx$ 2. By scaling the curves of
+resistivity vs. angle measured at a fixed temperature but different magnetic
+fields within the framework of the anisotropic Ginzburg-Landau theory, we
+obtained the anisotropy in an alternative way. Again we found that the
+anisotropy $(m_c/m_{ab})^{1/2}$ was close to 2. This value is very similar to
+that in Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ (K-doped Ba122) and
+Ba(Fe$_{0.92}$Co$_{0.08}$)$_2$As$_2$ (Co-doped Ba122). This suggests that the
+3D warping effect of the Fermi surface in Ru-doped samples may not be stronger
+than that in the K-doped or Co-doped Ba122 samples, therefore the possible
+nodes appearing in Ru-doped samples cannot be ascribed to the 3D warping effect
+of the Fermi surface.",1203.6793v1
+2012-04-17,"Comment on ""Joint Anisotropy and Source Count Constraints on the Contribution of Blazars to the Diffuse Gamma-Ray Background""","We show the conclusions claimed in the manuscript arXiv:1202.5309v1 by Cuoco,
+Komatsu and Siegal-Gaskins (CKS) are not generally valid. The results in CKS
+are based on a number of simplifying assumptions regarding the source
+population below the detection threshold and the threshold flux itself, and do
+not apply to many physical models of the blazar population. Physical blazar
+population models that match the measured source counts above the observational
+threshold can account for 60% of the diffuse gamma-ray background intensity
+between 1-10 GeV, while the assumptions in CKS limit the intensity to <30%. The
+shortcomings of the model considered in CKS arise from an over-simplified
+blazar source model. A number of the simplifying assumptions are unjustified,
+including: first, the adoption of an assumed power-law source-count
+distribution, dN/dS, to arbitrary low source fluxes, which is not exhibited in
+physical models of the blazar population; and, second, the lack of blazar
+spectral information in calculating the anisotropy of unresolved gamma-ray
+blazar emission. We also show that the calculation of the unresolved blazars'
+anisotropy is very sensitive to the spectral distribution of the unresolved
+blazars through the adopted source resolution threshold value, and must be
+taken into account in an accurate anisotropy calculation.",1204.3870v1
+2012-05-02,CMB polarization anisotropies from cosmological reionization: extension to B-modes,"The accurate understanding of the ionization history of the Universe plays a
+fundamental role in modern cosmology. It includes a phase of cosmological
+reionization after the standard recombination epoch, possibly associated to the
+early stages of structure and star formation. While the simple
+""{\tau}-parametrization"" of the reionization process and, in particular, of its
+imprints on the CMB anisotropy likely represents a sufficiently accurate
+modelling for the interpretation of current CMB data, a great attention has
+been recently posed on the accurate computation of the reionization signatures
+in the CMB for a large variety of astrophysical scenarios and physical
+processes. This work is aimed at a careful characterization of the imprints
+introduced in the polarization anisotropy, with particular attention to the
+B-modes. We have implemented a modified version of CAMB, the Cosmological
+Boltzmann code for computing the angular power spectrum (APS) of the
+anisotropies of the CMB, to introduce the hydrogen and helium ionization
+fractions predicted in astrophysical and phenomenological reionization
+histories, beyond the simple {\tau}-parametrization. We compared the results
+obtained for these models for all the non-vanishing (in the assumed scenarios)
+modes of the CMB APS. The amplitude and shape of the B-mode APS depends, in
+particular, on the tensor-to-scalar ratio, r, and on the reionization history,
+thus an accurate modeling of the reionization process will have implications
+for the precise determination of r or to set more precise constraints on it
+through the joint analysis of E and B-mode polarization data available in the
+next future and from a mission of next generation. Considering also the
+limitation from potential residuals of astrophysical foregrounds, we discussed
+the capability of next data to disentangle between different reionization
+scenarios in a wide range of r.",1205.0463v1
+2012-10-16,The effect of perception anisotropy on particle systems describing pedestrian flows in corridors,"We consider a microscopic model (a system of self-propelled particles) to
+study the behaviour of a large group of pedestrians walking in a corridor. Our
+point of interest is the effect of anisotropic interactions on the global
+behaviour of the crowd. The anisotropy we have in mind reflects the fact that
+people do not perceive (i.e. see, hear, feel or smell) their environment
+equally well in all directions. The dynamics of the individuals in our model
+follow from a system of Newton-like equations in the overdamped limit. The
+instantaneous velocity is modelled in such a way that it accounts for the angle
+under which an individual perceives another individual. We investigate the
+effects of this perception anisotropy by means of simulations, very much in the
+spirit of molecular dynamics. We define a number of characteristic quantifiers
+(including the polarization index and Morisita index) that serve as measures
+for e.g. organization and clustering, and we use these indices to investigate
+the influence of anisotropy on the global behaviour of the crowd. The goal of
+the paper is to investigate the potentiality of this model; extensive
+statistical analysis of simulation data, or reproducing any specific real-life
+situation are beyond its scope.",1210.4530v2
+2012-11-29,The sensitivity of Cherenkov telescopes to dark matter and astrophysical anisotropies in the diffuse gamma-ray background,"In this article, the capability of present (H.E.S.S., MAGIC, VERITAS) and
+planned (CTA) ground-based Cherenkov telescope systems for detecting angular
+anisotropies in the diffuse gamma-ray background is investigated. Following up
+on a study of the impact of instrumental characteristics (effective area, field
+of view, angular resolution, and background rejection efficiency), the first
+part examines the influence of different observational strategies, i.e. whether
+a single deep observation or a splitting over multiple shallow fields is
+preferred. In the second part, the sensitivity to anisotropies generated by
+self-annihilating dark matter is studied for different common dark matter
+models. We find that a relative contribution of ~10% from dark matter
+annihilation to the extra-galactic diffuse gamma-ray background can be detected
+with planned configurations of CTA. In terms of the thermally-averaged
+self-annihilation cross section, the sensitivity of CTA corresponds to values
+below the thermal freeze-out expectation <sigma v> = 3 x 10-26 cm3s-1 for dark
+matter particles lighter than ~200 GeV. We stress the importance of
+constraining anisotropies from unresolved astrophysical sources with currently
+operating instruments already, as a novel and complementary method for
+investigating the properties of TeV sources.",1211.6922v2
+2012-12-20,Numerical Renormalization Group calculations of the magnetization of isotropic and anisotropic Kondo impurities,"We study a Kondo impurity model with additional uniaxial anisotropy D in a
+non-zero magnetic field B using the Numerical Renormalization Group (NRG). The
+ratio g_e/g_S of electron and impurity g-factor is regarded as a free parameter
+and, in particular, the special cases of a ""local"" (g_e=0) and ""bulk"" (g_e=g_S)
+field are considered. For a bulk field, the relationship between the impurity
+magnetization M and the impurity contribution to the magnetization M_imp is
+investigated. Furthermore, we study how the value of g_e affects the impurity
+magnetization curves. In case of an isotropic impurity with g_e=g_S, it is
+demonstrated that at zero temperature M(B), unlike M_imp(B), does not display
+universal behavior. With additional ""easy axis"" anisotropy, the impurity
+magnetization is well described by a shifted and rescaled Brillouin function on
+energy scales that are small compared to |D|. In case of ""hard axis""
+anisotropy, the magnetization curves can feature steps which are due to
+field-induced pseudo-spin-1/2 Kondo effects. For large anisotropy and a local
+field, these screening effects are described by an anisotropic spin-1/2 Kondo
+model with an additional scattering term that is spin-dependent (in contrast to
+ordinary potential scattering). Our study is motivated by the question how the
+magnetic properties of a deposited magnetic molecule are modified by the
+interaction with a non-magnetic metallic surface.",1212.5007v1
+2013-01-08,Magnetic anisotropy in hole-doped superconducting Ba 0.67K 0.33Fe 2As2 probed by polarized inelastic neutron scattering,"We use polarized inelastic neutron scattering (INS) to study spin excitations
+of optimally hole-doped superconductor Ba$_{0.67}$K$_{0.33}$Fe$_2$As$_{2}$
+($T_c=38$ K).
+  In the normal state, the imaginary part of the dynamic susceptibility,
+$\chi^{\prime\prime}(Q,\omega)$, shows magnetic anisotropy for energies below
+$\sim$7 meV with c-axis polarized spin excitations larger than that of the
+in-plane component. Upon entering into the superconducting state, previous
+unpolarized INS experiments have shown that spin gaps at $\sim$5 and 0.75 meV
+open at wave vectors $Q=(0.5,0.5,0)$ and $(0.5,0.5,1)$, respectively, with a
+broad neutron spin resonance at $E_r=15$ meV. Our neutron polarization analysis
+reveals that the large difference in spin gaps is purely due to different spin
+gaps in the c-axis and in-plane polarized spin excitations, resulting resonance
+with different energy widths for the c-axis and in-plane spin excitations. The
+observation of spin anisotropy in both opitmally electron and hole-doped
+BaFe$_2$As$_2$ is due to their proximity to the AF ordered BaFe$_2$As$_2$ where
+spin anisotropy exists below $T_N$.",1301.1397v1
+2013-02-04,The flattening of globular clusters: internal rotation or velocity anisotropy?,"Internal rotation is considered to play a major role in determining the
+structure and dynamics of some globular clusters. We present a dynamical
+analysis of the photometry and three-dimensional kinematics of 47 Tuc and omega
+Cen, by means of a new family of self-consistent axisymmetric rotating models.
+The combined use of line-of-sight velocities and proper motions allows us to
+obtain a global description of the internal dynamical structure of the objects
+together with an estimate of their dynamical distances. The well-relaxed
+cluster 47 Tuc is very well interpreted by our dynamical models; in particular,
+internal rotation is found to explain the observed morphology. For the
+partially relaxed cluster omega Cen, the selected model provides a good
+representation of its complex three-dimensional kinematics, in general
+qualitative agreement with the observed anisotropy profile, which is
+characterized by tangential anisotropy in the outer parts; discrepancies are
+found between the observed and the expected ellipticity profile and are
+ascribed to the presence of a high degree of radial anisotropy in the
+intermediate region and to its interplay with rotation.",1302.0717v1
+2013-03-06,Magnetic field-induced gluonic (inverse) catalysis and pressure (an)isotropy in QCD,"We study the influence of strong external magnetic fields on gluonic and
+fermionic observables in the QCD vacuum at zero and nonzero temperatures, via
+lattice simulations with N_f=1+1+1 staggered quarks of physical masses. The
+gluonic action density is found to undergo magnetic catalysis at low
+temperatures and inverse magnetic catalysis near and above the transition
+temperature, similar to the quark condensate. Moreover, the gluonic action
+develops an anisotropy: the chromo-magnetic field parallel to the external
+field is enhanced, while the chromo-electric field in this direction is
+suppressed. We demonstrate that the same hierarchy is obtained using the
+Euler-Heisenberg effective action. Conversely, the topological charge density
+correlator does not reveal a significant anisotropy up to magnetic fields eB~1
+GeV^2. Furthermore, we show that the pressure remains isotropic even for
+nonzero magnetic fields, if it is defined through a compression of the system
+at fixed external field. In contrast, if the flux of the field is kept fixed
+during the compression -- which is the situation realized in the lattice
+simulation -- the pressure develops an anisotropy. We estimate the quark and
+gluonic contributions to this anisotropy, and relate them to the magnetization
+of the QCD vacuum. After performing electric charge renormalization, we obtain
+an estimate for the magnetization, which indicates that QCD is paramagnetic.",1303.1328v2
+2013-04-05,Probing the Pulsar Origin of the Anomalous Positron Fraction with AMS-02 and Atmospheric Cherenkov Telescopes,"Recent observations by PAMELA, Fermi-LAT, and AMS-02 have conclusively
+indicated a rise in the cosmic-ray positron fraction above 10 GeV, a feature
+which is impossible to mimic under the paradigm of secondary positron
+production with self-consistent Galactic cosmic-ray propagation models. A
+leading explanation for the rising positron fraction is an additional source of
+electron-positron pairs, for example one or more mature, energetic, and
+relatively nearby pulsars. We point out that any one of two well-known nearby
+pulsars, Geminga and Monogem, can satisfactorily provide enough positrons to
+reproduce AMS-02 observations. A smoking-gun signature of this scenario is an
+anisotropy in the arrival direction of the cosmic-ray electrons and positrons,
+which may be detectable by existing, or future, telescopes. The predicted
+anisotropy level is, at present, consistent with limits from Fermi-LAT and
+AMS-02. We argue that the large collecting area of Atmospheric Cherenkov
+Telescopes (ACTs) makes them optimal tools for detecting such an anisotropy.
+Specifically, we show that much of the proton and gamma-ray background, which
+affects measurements of the cosmic-ray electron-positron spectrum with ACTs,
+may be controlled in the search for anisotropies. We conclude that observations
+using archival ACT data could already constrain or substantiate the pulsar
+origin of the positron anomaly, while upcoming instruments (such as the
+Cherenkov Telescope Array) will provide strong constraints on the source of the
+rising positron fraction.",1304.1791v2
+2013-04-10,Constraints on the Sunyaev-Zel'dovich signal from the Warm Hot Intergalactic Medium from WMAP and SPT data,"The fraction of ionized gas in the Warm Hot Intergalactic Medium induces
+temperature anisotropies on the Cosmic Microwave Background similar to those of
+clusters of galaxies. The Sunyaev-Zel'dovich anisotropies due to these low
+density, weakly non-linear, baryon filaments can not be distinguished from that
+of clusters using frequency information, but they can be separated since their
+angular scales are very different. To determine the relative contribution of
+the WHIM SZ signal to the radiation power spectrum of temperature anisotropies,
+we explore the parameter space of the concordance LCDM model using Monte Carlo
+Markov Chains and the Wilkinson Microwave Anisotropy Probe 7yr and South Pole
+Telescope data. We find marginal evidence of a contribution by diffuse gas,
+with amplitudes of A_WHIM=10-20 muK^2, but the results are also compatible with
+a null contribution from the WHIM, allowing to set an upper limit of A_WHIM <
+43 muK^2 (95.4% C.L.). The signal produced by galaxy clusters remains at
+A_CL=4.5 muK^2, a value similar to what is obtained when no WHIM is included.
+From the measured WHIM amplitude we constrain the temperature-density phase
+diagram of the diffuse gas, and find it to be compatible with numerical
+simulations. The corresponding baryon fraction in the WHIM varies from 0.43 to
+0.47, depending on model parameters. Planck data could set tighter constraints
+on the temperature-density relation.",1304.2901v1
+2013-05-23,Holographic Photon Production with Magnetic Field in Anisotropic Plasmas,"We investigate the thermal photon production from constant magnetic field in
+a strongly coupled and anisotropic plasma via the gauge/gravity duality. The
+dual geometry with pressure anisotropy is generated from the axion-dilaton
+gravity action introduced by Mateos and Trancancelli and the magnetic field is
+coupled to fundamental matters(quarks) through the D3/D7 embeddings. We find
+that the photon spectra with different quark mass are enhanced at large
+frequency when the photons are emitted parallel to the anisotropic direction
+with larger pressure or perpendicular to the magnetic field. However, in the
+opposite conditions for the emitted directions, the spectra approximately
+saturate isotropic results in the absence of magnetic field. On the other hand,
+a resonance emerges at moderate frequency for the photon spectrum with heavy
+quarks when the photons move perpendicular to the magnetic field. The resonance
+is more robust when the photons are polarized along the magnetic field. On the
+contrary, in the presence of pressure anisotropy, the resonance will be
+suppressed. There exist competing effects of magnetic field and pressure
+anisotropy on meson melting in the strongly coupled super Yang-Mills plasma,
+while we argue that the suppression led by anisotropy may not be applied to the
+quark gluon plasma.",1305.5509v3
+2013-05-26,Rotating Globular Clusters,"Internal rotation is considered to play a major role in the dynamics of some
+globular clusters. However, in only few cases it has been studied by
+quantitative application of realistic and physically justified global models.
+Here we present a dynamical analysis of the photometry and three-dimensional
+kinematics of omega Cen, 47 Tuc, and M15, by means of a recently introduced
+family of self-consistent axisymmetric rotating models. The three clusters,
+characterized by different relaxation conditions, show evidence of differential
+rotation and deviations from sphericity. The combination of line-of-sight
+velocities and proper motions allows us to determine their internal dynamics,
+predict their morphology, and estimate their dynamical distance. The
+well-relaxed cluster 47 Tuc is very well interpreted by our model; internal
+rotation is found to explain the observed morphology. For M15, we provide a
+global model in good agreement with the data, including the central behavior of
+the rotation profile and the shape of the ellipticity profile. For the
+partially relaxed cluster omega Cen, the selected model reproduces the complex
+three-dimensional kinematics; in particular the observed anisotropy profile,
+characterized by a transition from isotropy, to weakly-radial anisotropy, and
+then to tangential anisotropy in the outer parts. The discrepancy found for the
+steep central gradient in the observed line-of-sight velocity dispersion
+profile and for the ellipticity profile is ascribed to the condition of only
+partial relaxation of this cluster and the interplay between rotation and
+radial anisotropy.",1305.6025v1
+2013-06-05,Statistical Anisotropy in Inflationary Models with Many Vector Fields and/or Prolonged Anisotropic Expansion,"We study the most general contributions due to scalar field perturbations,
+vector field perturbations, and anisotropic expansion to the generation of
+statistical anisotropy in the primordial curvature perturbation \zeta. Such a
+study is done using the \delta N formalism where only linear terms are
+considered. Here, we consider two specific cases that lead to determine the
+power spectrum P_\zeta(k) of the primordial curvature perturbation. In the
+first one, we consider the possibility that the n-point correlators of the
+field perturbations in real space are invariant under rotations in space
+(statistical isotropy); as a result, we obtain as many levels of statistical
+anisotropy as vector fields present and, therefore, several preferred
+directions. The second possibility arises when we consider anisotropic
+expansion, which leads us to obtain I+a additional contributions to the
+generation of statistical anisotropy of \zeta compared with the former case,
+being I and a the number of scalar and vector fields involved respectively.",1306.1150v1
+2013-07-29,Chiral Phases of Superfluid 3He in an Anisotropic Medium,"I report theoretical analysis and predictions for the equilibrium phases of
+superfluid 3He infused into a low-density, homogeneous uniaxial aerogel.
+Ginzburg-Landau (GL) theory for a class of equal-spin-pairing (ESP) states in a
+medium with uniaxial anisotropy is developed and used to analyze recent
+experiments on uniaxially strained aerogels. For 3He in an axially ""stretched""
+aerogel GL theory predicts a transition from normal liquid into a chiral ABM
+phase at T_c1 in which the chirality axis, l, is aligned along the strain axis.
+This orbitally aligned state, is protected from random fluctuations in the
+anisotropy direction, has a positive NMR frequency shift, a sharp NMR resonance
+line and is identified with the high-temperature ESP-1 phase of superfluid 3He
+in axially stretched aerogel. A second transition into a biaxial phase is
+predicted to onset at a slightly lower temperature, T_c2 < T_c1. This phase is
+an ESP state, breaks time-reversal symmetry, and is defined by an orbital order
+parameter that spontaneously breaks axial rotation symmetry. This transition is
+driven by the coupling of an axially aligned 1D ""polar"" order parameter to the
+two time-reversed 2D axial ABM states. The biaxial phase has a continuous
+degeneracy associated with the projection of its chiral axis in the plane
+normal to the anisotropy axis. Theoretical predictions for the NMR frequency
+shifts of the biaxial phase provide an identification of the ESP-2 as the
+biaxial state, partially disordered by random anisotropy (Larkin-Imry-Ma
+effect). The ""width"" of the jump in the NMR frequency shift at T_c2 provides an
+estimate of the orbital domain size, xi_LIM ~ 5 mu-m at 18 bar.",1307.7656v1
+2013-08-05,Thermally driven domain wall motion in Fe on W(1 1 0),"It has recently been shown that domain walls in ferromagnets can be moved in
+the presence of thermal gradients. In this work we study the motion of narrow
+domain walls in low-dimensional systems when subjected to thermal gradients.
+The system chosen is a monolayer of Fe on W(1 1 0) which is known to exhibit a
+large anisotropy while having a soft exchange, resulting in a very narrow
+domain wall. The study is performed by means of atomistic spin dynamics
+simulations coupled to first-principles calculations. By subjecting the systems
+to a thermal gradient we observe a temperature dependent movement of the domain
+wall as well as changes of the spatial magnetization profile of the system. The
+thermal gradient always makes the domain wall move towards the hotter region of
+the sample with a velocity proportional to the gradient. The material specific
+study is complemented by model simulations to discern the interplay between the
+thermal gradient, magnetic anisotropy and the exchange interaction, and shows
+that the larger DW velocities are found for materials with low magnetic
+anisotropy. The relatively slow DW motion of the Fe/W(1 1 0) system is hence
+primarily caused by its large magnetic anisotropy.",1308.0986v1
+2013-09-16,Limits on Alpha Particle Temperature Anisotropy and Differential Flow from Kinetic Instabilities: Solar Wind Observations,"Previous studies have shown that the observed temperature anisotropies of
+protons and alpha particles in the solar wind are constrained by theoretical
+thresholds for pressure-anisotropy-driven instabilities such as the
+Alfv\'en/ion-cyclotron (A/IC) and fast-magnetosonic/whistler (FM/W)
+instabilities. In this letter, we use a long period of in-situ measurements
+provided by the {\em Wind} spacecraft's Faraday cups to investigate the
+combined constraint on the alpha-proton differential flow velocity and the
+alpha-particle temperature anisotropy due to A/IC and FM/W instabilities. We
+show that the majority of the data are constrained to lie within the region of
+parameter space in which A/IC and FM/W waves are either stable or have
+extremely low growth rates. In the minority of observed cases in which the
+growth rate of the A/IC (FM/W) instability is comparatively large, we find
+relatively higher values of $T_{\perp\alpha}/T_{\perp p}$
+($T_{\parallel\alpha}/T_{\parallel p}$) when alpha-proton differential flow
+velocity is small, where $T_{\perp\alpha}$ and $T_{\perp p}$
+($T_{\parallel\alpha}$ and $T_{\parallel p}$) are the perpendicular (parallel)
+temperatures of alpha particles and protons. We conjecture that this observed
+feature might arise from preferential alpha-particle heating which can drive
+the alpha particles beyond the instability thresholds.",1309.4010v2
+2013-09-24,Medium scale anisotropy in the TeV cosmic ray flux observed by ARGO-YBJ,"Measuring the anisotropy of the arrival direction distribution of cosmic rays
+provides important information on the propagation mechanisms and the
+identification of their sources. In fact, the flux of cosmic rays is thought to
+be dependent on the arrival direction only due to the presence of nearby cosmic
+ray sources or particular magnetic-field structures. Recently, the observation
+of unexpected excesses at TeV energy down to angular scale as narrow as
+$\sim10\deg$ raised the possibility that the problem of the origin of galactic
+cosmic rays may be addressed by studying the anisotropy.
+  The ARGO-YBJ experiment is a full-coverage EAS array, sensitive to cosmic
+rays with energy threshold of a few hundred GeV. Searching for small-size
+deviations from the isotropy, the ARGO-YBJ collaboration explored the
+declination region $\delta\sim-20^{\circ}\div 80^{\circ}$, making use of about
+3.7$\cdot10^{11}$ events collected from November 2007 to May 2012.
+  In this paper the detection of different significant (up to 13 standard
+deviations) medium-scale anisotropy regions in the arrival directions of CRs is
+reported. The observation was performed with unprecedented detail. The relative
+excess intensity with respect to the isotropic flux extends up to 10$^{-3}$.
+The maximum excess occurs for proton energies of 10-20 TeV, suggesting the
+presence of unknown features of the magnetic fields the charged cosmic rays
+propagate through, or some contribution of nearby sources never considered so
+far.
+  The observation of new weaker few-degree excesses throughout the sky region
+$195^{\circ}\leq$ \ra $\leq 290^{\circ}$ is reported for the first time.",1309.6182v1
+2013-10-21,"Controlled nucleation of topological defects in the stripe domain patterns of Lateral multilayers with Perpendicular Magnetic Anisotropy: competition between magnetostatic, exchange and misfit interactions","Magnetic lateral multilayers have been fabricated on weak perpendicular
+magnetic anisotropy amorphous Nd-Co films in order to perform a systematic
+study on the conditions for controlled nucleation of topological defects within
+their magnetic stripe domain pattern. A lateral thickness modulation of period
+$w$ is defined on the nanostructured samples that, in turn, induces a lateral
+modulation of both magnetic stripe domain periods $\lambda$ and average
+in-plane magnetization component $M_{inplane}$. Depending on lateral multilayer
+period and in-plane applied field, thin and thick regions switch independently
+during in-plane magnetization reversal and domain walls are created within the
+in-plane magnetization configuration coupled to variable angle grain boundaries
+and disclinations within the magnetic stripe domain patterns. This process is
+mainly driven by the competition between rotatable anisotropy (that couples the
+magnetic stripe pattern to in-plane magnetization) and in-plane shape
+anisotropy induced by the periodic thickness modulation. However, as the
+structural period $w$ becomes comparable to magnetic stripe period $\lambda$,
+the nucleation of topological defects at the interfaces between thin and thick
+regions is hindered by a size effect and stripe domains in the different
+thickness regions become strongly coupled.",1310.5566v1
+2013-11-21,Jet Quenching and Its Azimuthal Anisotropy in AA and possibly High Multiplicity pA and dA Collisions,"We report our calculation of jet quenching and its azimuthal anisotropy in
+the high energy AA and high multiplicity pA and dA collisions. The purpose of
+this study is twofold. First, we improve our previous event-by-event studies,
+by properly implementing $p_t$ dependence in the modeling. We show that, within
+the jet ""monography"" scenario featuring a strong near-Tc-enhancement of jet
+energy loss, the computed high-$p_t$ nuclear modification factor $R_{AA}$ and
+the harmonic coefficients in its azimuthal anisotropy $v_{2,\,3,\,4}$, agree
+well with the available data from both Relativistic Heavy Ion Collider (RHIC)
+and Large Hadron Collider (LHC). Second, in light of current discussions on
+possible final state collective behavior in the high-multiplicity pPb and dAu
+collisions, we examine the implication of final state jet attenuation in such
+collisions, by applying the same model used in AA collisions and quantifying
+the corresponding $R_{pA}$ and $R_{dA}$ and their azimuthal anisotropy. The
+high-$p_t$ $V_n$ provide a set of clean indicators of final state energy loss.
+In particular we find in the most central pPb (5.02 TeV) and dAu (200 GeV)
+collisions, $V_2$ is on the order of $0.01$ and $0.1$ respectively, measurable
+with current experimental accuracy. In addition, our high-$p_t$ $R_{dA}$ is
+around $0.6$ which is compatible with preliminary dAu results from RHIC.",1311.5463v2
+2013-12-13,On Vortex Solutions of Landau-Lifshitz Equations,"We study the Landau-Lifshitz equation of ferromagnetism on $\mathbb{R}^2$
+with an easy-axis anisotropy. We give the necessary condition for the existence
+of the finite energy vortex solutions and show the behaviors of the solutions.",1312.3816v1
+2013-12-23,"Universal fluctuation-driven eccentricities in proton-proton, proton-nucleus and nucleus-nucleus collisions","We show that the statistics of fluctuation-driven initial-state anisotropies
+in proton-proton, proton-nucleus and nucleus-nucleus collisions is to a large
+extent universal. We propose a simple parametrization for the probability
+distribution of the Fourier coefficient $\varepsilon_n$ in harmonic $n$, which
+is in good agreement with Monte-Carlo simulations. Our results provide a simple
+explanation for the 4-particle cumulant of triangular flow measured in Pb-Pb
+collisions, and for the 4-particle cumulant of elliptic flow recently measured
+in p-Pb collisions. Both arise as natural consequences of the condition that
+initial anisotropies are bounded by unity. We argue that the initial rms
+anisotropy in harmonic $n$ can be directly extracted from the measured ratio
+$v_n\{4\}/v_n\{2\}$: this gives direct access to a property of the initial
+density profile from experimental data. We also make quantitative predictions
+for the small lifting of degeneracy between $v_n\{4\}$, $v_n\{6\}$ and
+$v_n\{8\}$. If confirmed by future experiments, they will support the picture
+that long-range correlations observed in p-Pb collisions at the LHC originate
+from collective flow proportional to the initial anisotropy.",1312.6555v3
+2014-01-17,Co2FeAl Heusler thin films grown on Si and MgO substrates: annealing temperature effect,"10 nm and 50 nm Co$_{2}$FeAl (CFA) thin films have been deposited on MgO(001)
+and Si(001) substrates by magnetron sputtering and annealed at different
+temperatures. X-rays diffraction revealed polycrystalline or epitaxial growth
+(according to the relation CFA(001)[110]//MgO(001)[100] epitaxial relation),
+respectively for CFA films grown on a Si and on a MgO substrate. For these
+later, the chemical order varies from the A2 phase to the B2 phase when
+increasing the annealing temperature (Ta) while only the A2 disorder type has
+been observed for CFA grown on Si. Microstrip ferromagnetic resonance (MS-FMR)
+measurements revealed that the in-plane anisotropy results from the
+superposition of a uniaxial and of a fourfold symmetry term for CFA grown on
+MgO substrates. This fourfold anisotropy, which disappears completely for
+samples grown on Si, is in accord with the crystal structure of the samples.
+The fourfold anisotropy field decreases when increasing Ta while the uniaxial
+anisotropy field is nearly unaffected by Ta within the investigated range. The
+MS-FMR data also allow for concluding that the gyromagnetic factor remains
+constant and that the exchange stiffness constant increases with $T_{a}$.
+Finally, the FMR linewidth decreases when increasing Ta, due to the enhancement
+of the chemical order. We derive a very low intrinsic damping parameter
+(1.3*10^-3 and 1.1*10^-3 for films of 50 nm thickness annealed at 615 {\deg}C
+grown on MgO and on Si, respectively).",1401.4397v1
+2014-02-05,Fieldlike and antidamping spin-orbit torques in as-grown and annealed Ta/CoFeB/MgO layers,"We present a comprehensive study of the current-induced spin-orbit torques in
+perpendicularly magnetized Ta/CoFeB/MgO layers. The samples were annealed in
+steps up to 300 degrees C and characterized using x-ray absorption
+spectroscopy, transmission electron microscopy, resistivity, and Hall effect
+measurements. By performing adiabatic harmonic Hall voltage measurements, we
+show that the transverse (field-like) and longitudinal (antidamping-like)
+spin-orbit torques are composed of constant and magnetization-dependent
+contributions, both of which vary strongly with annealing. Such variations
+correlate with changes of the saturation magnetization and magnetic anisotropy
+and are assigned to chemical and structural modifications of the layers. The
+relative variation of the constant and anisotropic torque terms as a function
+of annealing temperature is opposite for the field-like and antidamping
+torques. Measurements of the switching probability using sub-{\mu}s current
+pulses show that the critical current increases with the magnetic anisotropy of
+the layers, whereas the switching efficiency, measured as the ratio of magnetic
+anisotropy energy and pulse energy, decreases. The optimal annealing
+temperature to achieve maximum magnetic anisotropy, saturation magnetization,
+and switching efficiency is determined to be between 240 degrees and 270
+degrees C.",1402.0986v2
+2014-02-26,Giant magnetic anisotropy and tunnelling of the magnetization in Li2(Li_{1-x}Fe_x)N,"Large magnetic anisotropy and coercivity are key properties of functional
+magnetic materials and are generally associated with rare earth elements. Here
+we show an extreme, uniaxial magnetic anisotropy and the emergence of magnetic
+hysteresis in Li2(Li1-xFex)N. An extrapolated, magnetic anisotropy field of 220
+Tesla and a coercivity field of over 11 Tesla at 2 Kelvin outperform all known
+hard-ferromagnets and single-molecule magnets (SMMs). Steps in the hysteresis
+loops and relaxation phenomena in striking similarity to SMMs are particularly
+pronounced for x << 1 and indicate the presence of nano-scale magnetic centres.
+Quantum tunnelling, in form of temperature-independent relaxation and
+coercivity, deviation from Arrhenius behaviour and blocking of the relaxation,
+dominates the magnetic properties up to 10 Kelvin. The simple crystal
+structure, the availability of large single crystals, and the ability to vary
+the Fe concentration make Li2(Li1-xFex)N (i) an ideal model system to study
+macroscopic quantum effects at elevated temperatures and (ii) a basis for novel
+functional magnetic materials.",1402.6626v1
+2014-03-22,Constraining anisotropy of the universe from different groups of type-Ia supernovae,"Recent released Planck data and other astronomical observations show that the
+universe may be anisotropic on large scales. Inspired by this, anisotropic
+cosmological models have been proposed. We note that the Finsler-Randers
+spacetime provides an appropriate framework for the anisotropic cosmology. By
+adding an arbitrary 1-form to the Friedmann-Robertson-Walker (FRW) line
+element, a privileged axis in the universe is picked out. The distance-redshift
+relation is modified to be direction-dependent. We wish that the anisotropic
+cosmological model may be tested crossly by independent observations. Type-Ia
+supernovae (SNe Ia) calibrated from four different light curve fitters are used
+to constrain possible anisotropy of the universe. The magnitudes of anisotropy
+are all between 2% --- 5%, but the systematic uncertainty cannot be excluded.
+The directions of privileged axis seem to differ from each other. The
+statistical significance is not high enough to make a convincing conclusion.
+Nevertheless, the $1\sigma$ contours in the $(l,b)$ plane obtained from four
+groups of SNe Ia have an overlap, centering at $(l,b)\approx
+(170^{\circ},0^{\circ})$. Monte Carlo simulation shows that the anisotropy is
+unlikely to be caused by selection effect.",1403.5661v1
+2014-04-07,Long term variation of the solar diurnal anisotropy of galactic cosmic rays observed with the Nagoya multi-directional muon detector,"We analyze the three dimensional anisotropy of the galactic cosmic ray (GCR)
+intensities observed independently with a muon detector at Nagoya in Japan and
+neutron monitors over four solar activity cycles. We clearly see the phase of
+the free-space diurnal anisotropy shifting toward earlier hours around solar
+activity minima in A>0 epochs, due to the reduced anisotropy component parallel
+to the mean magnetic field. The average parallel component is consistent with a
+rigidity independent spectrum, while the perpendicular component increases with
+GCR rigidity. We suggest that this harder spectrum of the perpendicular
+component is due to contribution from the drift streaming. We find that the
+bidirectional latitudinal density gradient is positive in A>0 epoch, while it
+is negative in A<0 epoch, in accord with the drift model prediction. The radial
+density gradient, on the other hand, varies with ~11-year cycle with maxima
+(minima) in solar maximum (minimum) periods, but there is no significant
+difference seen between average radial gradients in A>0 and A<0 epochs. The
+average parallel mean free path is larger in A<0 than in A>0. We also find,
+however, that parallel mean free path (radial gradient) appears to persistently
+increase (decreasing) in the last three cycles of weakening solar activity. We
+suggest that simple differences between these parameters in A>0 and A<0 epochs
+are seriously biased by these long-term trends.",1404.1676v2
+2014-05-08,Dynamical Condensation in a Holographic Superconductor Model with Anisotropy,"We study dynamical condensation process in a holographic superconductor model
+with anisotropy. The time-dependent numerical solution is constructed for the
+Einstein-Maxwell-dilaton theory with complex scalar in asymptotic AdS
+spacetime. The introduction of dilaton field generates the anisotropy in
+boundary spatial directions. In analogy of isotropic case, we have two black
+hole solutions below certain critical temperature $T_c$, the anisotropic
+charged black hole with and without scalar hair, corresponding respectively to
+the supercooled normal phase and superconducting phase in the boundary theory.
+We observe a nonlinear evolution from a supercooled anisotropic black hole
+without scalar hair to a anisotropic hairy black hole. Via AdS/CFT
+correspondence, we extract time evolution of the condensate operator, which
+shows an exponential growth and subsequent saturation, similar to the isotropic
+case. Furthermore, we obtain a nontrivial time evolution of the boundary
+pressure, while in isotropic case it remains a constant. We also generalize
+quasinormal modes calculation to anisotropic black holes and shows scalar
+quasinormal modes match with relaxation time scale of the condensate operator.
+In addition, we present the final temperature and anisotropic pressure as
+functions of initial temperature and background anisotropy.",1405.1806v2
+2014-05-08,Magnetic anisotropy and chirality of frustrated Cr nanostructures on Au(111),"By using a fully relativistic embedded cluster Green's function technique we
+investigated the magnetic anisotropy properties of four different compact Cr
+trimers (equilateral triangles) and Cr mono-layers deposited on Au(111) surface
+in both fcc and hcp stackings. For all trimers the magnetic ground state was
+found a frustrated 120$^\circ$ N\'eel configuration. Applying global spin
+rotations to the magnetic ground state, the predictions of an appropriate
+second order spin Hamiltonian were reproduced with high accuracy by the first
+principles calculations. For the Cr trimers with adjacent Au atoms in similar
+geometry we obtained similar values for the in-plane and out-of-plane
+anisotropy parameters, however, the Dzyaloshinskii-Moriya (DM) interactions
+appeared to differ remarkably. For two kinds of trimers we found an
+unconventional magnetic ground state showing 90$^\circ$ in-the-plane rotation
+with respect to the high symmetry directions. Due to higher symmetry, the
+in-plane anisotropy term was missing for the mono-layers and distinctly
+different DM interactions were obtained for the different stackings. The chiral
+degeneracy of the N\'eel configurations was lifted by less then 2 meV for the
+trimers, while this value raised up to about 15 meV per 3 Cr atoms for the hcp
+packed mono-layer.",1405.2057v1
+2014-05-16,Mixed configuration ground state in Iron(II) Phthalocyanine,"We calculate the angular dependence of the x-ray linear and circular
+dichroism at the $L_{2,3}$ edges of $\alpha$-Fe(II) Phthalocyanine (FePc) thin
+films using a ligand field model with full configuration interaction. We find
+the best agreement with the experimental spectra for a mixed ground state of
+$^3E_{g}(a_{1g}^2e_g^3b_{2g}^1)$ and $^3B_{2g}(a_{1g}^1e_g^4b_{2g}^1)$ with the
+two configurations coupled by the spin-orbit interaction. The $^3E_{g}(b)$ and
+$^3B_{2g}$ states have an easy axis and plane anisotropies, respectively. Our
+model accounts for an easy-plane magnetic anisotropy and the measured
+magnitudes of the in-plane orbital and spin moments. The proximity in energy of
+the two configurations allows a switching of the magnetic anisotropy from easy
+plane to easy axis with a small change in the crystal field, as recently
+observed for FePc adsorbed on an oxidized Cu surface. We also discuss the
+possibility of a quintet ground state ($^5A_{1g}$ is 250~meV above the ground
+state) with planar anisotropy by manipulation of the Fe-C bond length by
+depositing the complex on a substrate that is subjected to a mechanical strain.",1405.4313v4
+2014-05-23,Evolution of Anisotropic In-plane Resistivity with doping level in Ca$_{1-x}$Na$_x$Fe$_2$As$_2$ Single Crystals,"We measured the in-plane resistivity anisotropy in the underdoped
+Ca$_{1-x}$Na$_x$Fe$_2$As$_2$ single crystals. The anisotropy (indicated by
+$\rho_{\rm b} - \rho_{\rm a}$) appears below a temperature well above magnetic
+transition temperature $T_{\rm N}$, being positive ($\rho_{\rm b} - \rho_{\rm
+a} > 0$) as $x\leq$ 0.14. With increasing the doping level to $x$ = 0.19, an
+intersection between $\rho_{\rm b}$ and $\rho_{\rm a}$ is observed upon
+cooling, with $\rho_{\rm b} - \rho_{\rm a} < 0$ at low-temperature deep inside
+a magnetically ordered state, while $\rho_{\rm b} - \rho_{\rm a}> 0$ at high
+temperature. Subsequently, further increase of hole concentration leads to a
+negative anisotropy $\rho_{\rm b} - \rho_{\rm a} < 0$ in the whole temperature
+range. These results manifest that the anisotropic behavior of resistivity in
+the magnetically ordered state depends strongly on the competition of the
+contributions from different mechanisms, and the competition between the two
+contributions results in a complicated evolution of the anisotropy of in-plane
+resistivity with doping level.",1405.6199v1
+2014-06-23,Magnetic phases in the S=1 Shastry-Sutherland model with uniaxial anisotropy,"We explore the field induced magnetic phases of an $S=1$ $XXZ$ model with
+single-ion anisotropy and large Ising-like anisotropy on a Shastry Sutherland
+lattice over a wide range of Hamiltonian parameters and applied magnetic field.
+The multitude of ground state phases are characterized in detail in terms of
+their thermodynamic properties and the underlying classical (Ising limit) spin
+arrangements for the plateau phases are identified by calculating the static
+structure factors. The enlarged local Hilbert space of the $S=1$ spins results
+in several new ground state phases that are not realized for $S=1/2$ spins.
+These include the quantum paramagnetic state that is ubiquitous to $S=1$ spins
+with single ion anisotropy, two different spin supersolid phases (with distinct
+longitudinal ordering) and a magnetization plateau that arises as a direct
+descendant of the 1/3 plateau due to quantum fluctuations that are not possible
+for $S=1/2$ spins. We predict the same mechanism will lead to plateaus at
+smaller fractions of 1/3 for higher spins. The full momentum dependence of the
+longitudinal and transverse components of the static structure factor is
+calculated in the spin supersolid phase to demonstrate the simultaneous
+existence of diagonal and off-diagonal long-range order as well as the
+different longitudinal orderings.",1406.5856v1
+2014-08-20,The redshift-space galaxy two-point correlation function and baryon acoustic oscillations,"Future galaxy surveys will measure baryon acoustic oscillations (BAOs) with
+high significance, and a complete understanding of the anisotropies of BAOs in
+redshift space will be important to exploit the cosmological information in
+BAOs. Here we describe the anisotropies that arise in the redshift-space galaxy
+two-point correlation function (2PCF) and elucidate the origin of features that
+arise in the dependence of the BAOs on the angle between the orientation of the
+galaxy pair and the line of sight. We do so with a derivation of the
+configuration-space 2PCF using streaming model. We find that, contrary to
+common belief, the locations of BAO peaks in the redshift-space 2PCF are
+anisotropic even in the linear theory. Anisotropies in BAO depend strongly on
+the method of extracting the peak, showing maximum 3 % angular variation. We
+also find that extracting the BAO peak of $r^2\xi(r,\mu)$ significantly reduces
+the anisotropy to sub-percent level angular variation. When subtracting the
+tilt due to the broadband behavior of the 2PCF, the BAO bump is enhanced along
+the line of sight because of local infall velocities toward the BAO bump.
+Precise measurement of the angular dependence of the redshift-space 2PCF will
+allow new geometrical tests of dark energy beyond the BAO.",1408.4648v1
+2014-11-12,Large perpendicular magnetic anisotropy in magnetostrictive Fe$_{1-x}$Ga$_x$ thin films,"In this work we report the appearence of a large perpendicular magnetic
+anisotropy (PMA) in Fe$_{1-x}$Ga$_x$ thin films grown onto ZnSe/GaAs(100). This
+arising anisotropy is related to the tetragonal metastable phase in as-grown
+samples recently reported [M. Eddrief {\it et al.}, Phys. Rev. B {\bf 84},
+161410 (2011)]. By means of ferromagnetic resonance studies we measured PMA
+values up to $\sim$ 5$\times$10$^5$ J/m$^3$. PMA vanishes when the cubic
+structure is recovered upon annealing at 300$^{\circ}$C. Despite the important
+values of the magnetoelastic constants measured via the cantilever method, the
+consequent magnetoelastic contribution to PMA is not enough to explain the
+observed anisotropy values in the distorted state. {\it Ab initio} calculations
+show that the chemical ordering plays a crucial role in the appearance of PMA.
+Through a phenomenological model we are able to explain that an excess of next
+nearest neighbour Ga pairs (B$_2$-like ordering) along the perpendicular
+direction arises as the source of PMA in Fe$_{1-x}$Ga$_x$ thin films.",1411.3055v2
+2014-11-17,On the Anisotropy of Nuclei Mid-Infrared Radiation in Nearby Active Galactic Nuclei,"In the center of active galactic nuclei (AGN), the dusty torus absorb the
+radiation from the central engine and re-emit in mid-infrared (MIR).
+Observations have detected moderate anisotropy in the dust MIR emission, in the
+way that type 1 AGNs (type1s) are mildly brighter in MIR comparing with type 2
+sources (type2s). However, type1s and type2s were found to follow statistically
+the same tight MIR -- hard X-ray correlation, suggesting the MIR emission is
+highly isotropic assuming the hard X-ray radiation is inclination independent.
+We argue this discrepancy could be solved considering the hard X-ray emission
+in AGN is also mildly anisotropic as we recently discovered. To verify this
+diagram, we compare the sub-arcsecond 12\mu m flux densities of type1s and
+type2s using [OIV]$\lambda$25.89\mu m emission line as an isotropic luminosity
+indicator. We find that on average type1s are brighter in nuclei 12\mu m
+radiation by a factor of $2.6 \pm 0.6$ than type2s at given
+[OIV]$\lambda$25.89\mu m luminosities, confirming the mild anisotropy of the
+nuclei 12\mu m emission. We show that the anisotropy of the 12\mu m emission we
+detected is in good agreement with radiative transfer models of clumpy torus.
+The fact that type 1 and type 2 AGNs follow the same tight MIR -- hard X-ray
+correlation instead supports that both the MIR and hard X-ray emission in AGNs
+are mildly anisotropic.",1411.4585v1
+2014-12-08,Voltage Controlled Magnetic Anisotropy Based Low Energy Switching of a Ferromagnet on a Topological Insulator,"We present a novel memory device that consists of a thin ferromagnetic layer
+of Fe deposited on topological insulator thin film, Bi2Se3. The ferromagnetic
+layer has perpendicular anisotropy, due to MgO deposited on the top surface of
+Fe. When current is passed on the surface of Bi2Se3, the surface of the Bi2Se3
+becomes spin polarized and strong exchange interaction occurs between the d
+electrons in the ferromagnet and the electrons conducting the current on the
+surface of the Bi2Se3. Part of the current is shunted through the ferromagnet
+which generates spin transfer torque in the ferromagnet. The combination of the
+spin transfer torque and exchange interaction torque along with
+voltage-controlled magnetic anisotropy (VCMA) allows ultralow-energy switching
+of the ferromagnet. We perform micromagnetic simulations and predict switching
+time of the order of 2.5 ns and switching energy of the order of 0.45fJ for a
+ferromagnetic bit with thermal stability of 43kBT. Such ultralow-energy and
+high-speed VCMA-induced switching of a perpendicular anisotropy ferromagnet on
+a topological insulator could be utilized for energy-efficient memory design.",1412.2434v3
+2014-12-09,Anisotropy-based optimal filtering in linear discrete time invariant systems,"This paper is concerned with a problem of robust filtering for a
+finite-dimensional linear discrete time invariant system with two output
+signals, one of which is directly observed while the other has to be estimated.
+The system is assumed to be driven by a random disturbance produced from the
+Gaussian white noise sequence by an unknown shaping filter. The worst-case
+performance of an estimator is quantified by the maximum ratio of the
+root-mean-square (RMS) value of the estimation error to that of the disturbance
+over stationary Gaussian disturbances whose mean anisotropy is bounded from
+above by a given parameter $a \ge 0$. The mean anisotropy is a combined entropy
+theoretic measure of temporal colouredness and spatial ""nonroundness"" of a
+signal. We construct an $a$-anisotropic estimator which minimizes the
+worst-case error-to-noise RMS ratio. The estimator retains the general
+structure of the Kalman filter, though with modified state-space matrices.
+Computing the latter is reduced to solving a set of two coupled algebraic
+Riccati equations and an equation involving the determinant of a matrix. In two
+limiting cases, where $a = 0$ or $a \to +\infty$, the $a$-anisotropic estimator
+leads to the standard steady-state Kalman filter or the $H_{\infty}$-optimal
+estimator, respectively.",1412.3010v1
+2015-01-05,Anisotropic Strong Coupling Effects on Superfluid 3He in Aerogels - Conventional Spin-Fluctuation Approach -,"Motivated by recent experiments on liquid $^3$He reporting emergence of novel
+superfluid phases in globally anisotropic aerogels, our previous theory on
+superfluid $^3$He in globally anisotropic aerogels is extended to incorporate
+effects of an anisotropy of the quasiparticle scattering cross section on the
+strong coupling (SC) contributions to the Ginzburg-Landau (GL) free energy on
+the basis of the spin-fluctuation (paramagnon) approach to the SC contributions
+developed by Brinkman et al. [Phys. Rev. A {\bf 10}, 2386 (1974)]. In the
+globally isotropic case, impurity effects on the SC correction destabilize the
+A-phase even at higher pressures of about 30 (bar) and make the B-phase the
+only state in equilibrium, while SC contributions accompanied by a global
+stretched anisotropy to the GL quartic terms generally tend to broaden the
+stability region of the A-phase compared with that of the B-phase. In
+particular, in contrast to the cases in bulk and in the isotropic aerogel, the
+SC corrections to the GL {\it quadratic} terms are not negligible in the
+globally anisotropic case but may change the sign of the apparent anisotropy
+depending on the magnitude of the frequency cutoff of the normal paramagnon
+propagator. Based on this sign change of the apparent anisotropy, we discuss
+different strange observations on superfluid $^3$He in porous media such as
+disappearance of the polar superfluid phase at higher pressures seen in
+nematically-ordered aerogels and absence of the B-phase and of the A-phase with
+planar ${\hat {\bf l}}$-vector in a stretched aerogel.",1501.00795v1
+2015-02-02,Giant Phononic Anisotropy and Unusual Anharmonicity of Phosphorene: Interlayer Coupling and Strain Engineering,"Phosphorene, an emerging elemental two-dimensional (2D) direct band gap
+semiconductor with fascinating structural and electronic properties
+distinctively different from other 2D materials such as graphene and MoS2, is
+promising for novel nanoelectronic and optoelectronic applications. Phonons, as
+one of the most important collective excitations, are at the heart for the
+device performance, as their interactions with electrons and photons govern the
+carrier mobility and light-emitting efficiency of the material. Here, through a
+detailed first-principles study, it is demonstrated that monolayer phosphorene
+exhibits a giant phononic anisotropy, and remarkably, this anisotropy is
+squarely opposite to its electronic counterpart and can be tuned effectively by
+strain engineering. By sampling the whole Brillouin zone for the mono-layer
+phosphorene, several ""hidden"" directions are found, along which small-momentum
+phonons are ""frozen"" with strain and possess the smallest degree of
+anharmonicity. Unexpectedly, these ""hidden"" directions are intrinsically
+different from those usually studied armchair and zigzag directions. Light is
+also shed on the anisotropy of interlayer coupling of few-layer phosphorene by
+examining the rigid-layer vibrations. These highly anisotropic and
+strain-tunable characteristics of phosphorene offer new possibilities for its
+applications in thermal management, thermoelectronics, nanoelectronics and
+phononics.",1502.00375v1
+2015-02-04,Azimuthal anisotropies in p+Pb collisions from classical Yang-Mills dynamics,"We compute single and double inclusive gluon distributions in classical
+Yang-Mills simulations of proton-lead collisions and extract the associated
+transverse momentum dependent Fourier harmonics $v_2(p_T)$ and $v_3(p_T)$.
+Gluons have a large $v_2$ in the initial state, while odd harmonics such as
+$v_3$ vanish identically at the initial time $\tau=0^{+}$. By the time $\tau
+\lesssim 0.4\,{\rm fm/c}$ final state effects in the classical Yang-Mills
+evolution generate a non-zero $v_{3}$ and only mildly modify the gluon $v_{2}$.
+Unlike hydrodynamic flow, these momentum space anisotropies are uncorrelated
+with the global spatial anisotropy of the collision. A principal ingredient for
+the generation of $v_2$ and $v_3$ in this framework is the event-by-event
+breaking of rotational invariance in domains the size of the inverse of the
+saturation scale $Q_s$. In contrast to our findings in p+Pb collisions
+Yang-Mills simulations of lead-lead collisions generate much smaller values of
+$v_{2,3} (p_T)$ and additional collective flow effects are needed to explain
+experimental data. This is because the locally generated anisotropy due to the
+breaking of rotational invariance is depleted with the increase in the number
+of uncorrelated domains.",1502.01331v2
+2015-02-21,Statistical analysis of the velocity and scalar fields in reacting turbulent wall-jets,"The concept of local isotropy in a chemically reacting turbulent wall-jet
+flow is addressed using direct numerical simulation (DNS) data. Different DNS
+databases with isothermal and exothermic reactions are examined. The chemical
+reaction and heat release effects on the turbulent velocity, passive scalar and
+reactive species fields are studied using their probability density functions
+(PDF) and higher order moments for velocities and scalar fields, as well as
+their gradients. With the aid of the anisotropy invariant maps for the Reynolds
+stress tensor the heat release effects on the anisotropy level at different
+wall-normal locations are evaluated and found to be most accentuated in the
+near-wall region. It is observed that the small-scale anisotropies are
+persistent both in the near-wall region and inside the jet flame. Two
+exothermic cases with different Damkohler number are examined and the
+comparison revealed that the Damkohler number effects are most dominant in the
+near-wall region, where the wall cooling effects are influential. In addition,
+with the aid of PDFs conditioned on the mixture fraction, the significance of
+the reactive scalar characteristics in the reaction zone is illustrated. We
+argue that the combined effects of strong intermittency and strong persistency
+of anisotropy at the small scales in the entire domain can affect mixing and
+ultimately the combustion characteristics of the reacting flow.",1502.06113v1
+2015-04-09,Consequences of critical interchain couplings and anisotropy on a Haldane chain,"Effects of interchain couplings and anisotropy on a Haldane chain have been
+investigated by single crystal inelastic neutron scattering and density
+functional theory (DFT) calculations on the model compound SrNi$_2$V$_2$O$_8$.
+Significant effects on low energy excitation spectra are found where the
+Haldane gap ($\Delta_0 \approx 0.41J$; where $J$ is the intrachain exchange
+interaction) is replaced by three energy minima at different antiferromagnetic
+zone centers due to the complex interchain couplings. Further, the triplet
+states are split into two branches by single-ion anisotropy. Quantitative
+information on the intrachain and interchain interactions as well as on the
+single-ion anisotropy are obtained from the analyses of the neutron scattering
+spectra by the random phase approximation (RPA) method. The presence of
+multiple competing interchain interactions is found from the analysis of the
+experimental spectra and is also confirmed by the DFT calculations. The
+interchain interactions are two orders of magnitude weaker than the
+nearest-neighbour intrachain interaction $J$ = 8.7~meV. The DFT calculations
+reveal that the dominant intrachain nearest-neighbor interaction occurs via
+nontrivial extended superexchange pathways Ni--O--V--O--Ni involving the empty
+$d$ orbital of V ions. The present single crystal study also allows us to
+correctly position SrNi$_2$V$_2$O$_8$ in the theoretical $D$-$J_{\perp}$ phase
+diagram [T. Sakai and M. Takahashi, Phys. Rev. B 42, 4537 (1990)] showing where
+it lies within the spin-liquid phase.",1504.02400v1
+2015-05-22,Spectral distortions of the CMB dipole,"We consider the distortions of the cosmic microwave background (CMB) dipole
+anisotropy related to the primordial recombination radiation (PRR) and
+primordial $y$- and $\mu$-distortions. The signals arise due to our motion
+relative to the CMB restframe and appear as a frequency-dependent distortion of
+the CMB temperature dipole. To leading order, the expected relative distortion
+of the CMB dipole does not depend on the particular observation directions and
+reaches the level of $10^{-6}$ for the PRR- and $\mu$-distortions and $10^{-5}$
+for the $y$-distortion in the frequency range 1 -- 700 GHz. The temperature
+differences arising from the dipole anisotropy of the relic CMB distortions
+depend on the observation directions. For mutually opposite directions,
+collinear to the CMB dipole axis, the temperature differences because of the
+PRR- and $\mu$-dipole anisotropy attain values $\Delta T\simeq 10\,$nK in the
+considered range. The temperature difference arising from the $y$-dipole
+anisotropy may reach values of up to $1\,\mu$K. The key features of the
+considered effect are as follow: (i) an observation of the effect does not
+require absolute calibration; (ii) patches of sky with minimal foreground
+contamination can be chosen. Future measurements of the CMB dipole distortion
+thus will provide an alternative method for direct detection of the PRR-, $y$-,
+and $\mu$-distortions. The $y$-distortion dipole may be detectable with PIXIE
+at a few standard deviations.",1505.06028v2
+2015-05-26,Reference Interaction Site Model and Optimized Perturbation theories of colloidal dumbbells with increasing anisotropy,"We investigate thermodynamic properties of anisotropic colloidal dumbbells in
+the frameworks provided by the Reference Interaction Site Model (RISM) theory
+and an Optimized Perturbation Theory (OPT), this latter based on a fourth-order
+high-temperature perturbative expansion of the free energy, recently
+generalized to molecular fluids. Our model is constituted by two identical
+tangent hard spheres surrounded by square-well attractions with same widths and
+progressively different depths. Gas-liquid coexistence curves are obtained by
+predicting pressures, free energies, and chemical potentials. In comparison
+with previous simulation results, RISM and OPT agree in reproducing the
+progressive reduction of the gas-liquid phase separation as the anisotropy of
+the interaction potential becomes more pronounced; in particular, the RISM
+theory provides reasonable predictions for all coexistence curves, bar the
+strong anisotropy regime, whereas OPT performs generally less well. Both
+theories predict a linear dependence of the critical temperature on the
+interaction strength, reproducing in this way the mean-field behavior observed
+in simulations; the critical density~--~that drastically drops as the
+anisotropy increases~--~turns to be less accurate. Our results appear as a
+robust benchmark for further theoretical studies, in support to the simulation
+approach, of self-assembly in model colloidal systems.",1505.06952v1
+2015-06-07,Temperature dependent three-dimensional anisotropy of the magnetoresistance in WTe$_2$,"Extremely large magnetoresistance (XMR) was recently discovered in WTe$_2$,
+triggering extensive research on this material regarding the XMR origin. Since
+WTe$_2$ is a layered compound with metal layers sandwiched between adjacent
+insulating chalcogenide layers, this material has been considered to be
+electronically two-dimensional (2D). Here we report two new findings on
+WTe$_2$: (1) WTe$_2$ is electronically 3D with a mass anisotropy as low as $2$,
+as revealed by the 3D scaling behavior of the resistance
+$R(H,\theta)=R(\varepsilon_\theta H)$ with $\varepsilon_\theta =(\cos^2 \theta
++ \gamma^{-2}\sin^2 \theta)^{1/2}$, $\theta$ being the magnetic field angle
+with respect to c-axis of the crystal and $\gamma$ being the mass anisotropy;
+(2) the mass anisotropy $\gamma$ varies with temperature and follows the
+magnetoresistance behavior of the Fermi liquid state. Our results not only
+provide a general scaling approach for the anisotropic magnetoresistance but
+also are crucial for correctly understanding the electronic properties of
+WTe$_2$, including the origin of the remarkable 'turn-on' behavior in the
+resistance versus temperature curve, which has been widely observed in many
+materials and assumed to be a metal-insulator transition.",1506.02214v2
+2015-07-18,Tensor anisotropy as a tracer of cosmic voids,"We present a new method to find voids in cosmological simulations based on
+the tidal and the velocity shear tensors definitions of the cosmic web. We use
+the fractional anisotropy (FA) computed from the eigenvalues of each web scheme
+as a void tracer. We identify voids using a watershed transform based on the
+local minima of the FA field without making any assumption on the shape or
+structure of the voids. We test the method on the Bolshoi simulation and report
+on the abundance and radial averaged profiles for the density, velocity and
+fractional anisotropy. We find that voids in the velocity shear web are smaller
+than voids in the tidal web, with a particular overabundance of very small
+voids in the inner region of filaments/sheets. We classify voids as
+subcompensated/overcompansated depending on the absence/presence of an
+overdense matter ridge in their density profile, finding that close to $65\%$
+and $35\%$ of the total population are classified into each category,
+respectively. Finally, we find evidence for the existence of universal profiles
+from the radially averaged profiles for density, velocity and fractional
+anisotropy. This requires that the radial coordinate is normalized to the
+effective radius of each void. Put together, all these results show that the FA
+is a reliable tracer for voids, which can be used in complementarity to other
+existing methods and tracers.",1507.05178v1
+2015-08-06,Crossing Statistics of Anisotropic Stochastic Surface,"In this paper, we propose crossing statistics and its generalization, as a
+new framework to characterize the anisotropy in a 2D field, e.g. height on a
+surface, extendable to higher dimensions. By measuring $\nu^+$, the number of
+up-crossing (crossing points with positive slope at a given threshold of height
+($\alpha$)), and $N_{tot}$ (the generalized roughness function), it is possible
+to distinguish the nature of anisotropy, rotational invariance and Gaussianity
+of any given surface. For the case of anisotropic correlated self- or
+multi-affine surfaces (even with different correlation lengths in various
+directions and/or directional scaling exponents), we analytically derive some
+relations between $\nu^+$ and $N_{tot}$ with corresponding scaling parameters.
+The method systematically distinguishes the directions of anisotropy, at
+$3\sigma$ confidence interval using P-value statistics. After applying a
+typical method in determining the corresponding scaling exponents in identified
+anisotropic directions, we are able to determine the kind and ratio of
+correlation length anisotropy. To demonstrate capability and accuracy of the
+method, as well validity of analytical relations, our proposed measures are
+calculated on synthetic stochastic rough interfaces and rough interfaces
+generated from simulation of ion etching. There are good consistencies between
+analytical and numerical computations. The proposed algorithm can be mounted
+with a simple software on various instruments for surface analysis and
+characterization, such as AFM, STM and etc.",1508.01409v2
+2015-08-26,Order and excitations in large-$S$ kagomé-lattice antiferromagnets,"We systematically investigate the ground-state and the spectral properties of
+antiferromagnets on a kagom\'{e} lattice with several common types of the
+planar anisotropy: $XXZ$, single-ion, and out-of-plane Dzyaloshinskii-Moriya.
+Our main focus is on the role of nonlinear, anharmonic terms, which are
+responsible for the quantum order-by-disorder effect and for the corresponding
+selection of the ground-state spin structure in many of these models. The $XXZ$
+and the single-ion anisotropy models exhibit a quantum phase transition between
+the ${\bf q}\!=\!0$ and the $\sqrt{3}\times\!\sqrt{3}$ states as a function of
+the anisotropy parameter, offering a rare example of the quantum
+order-by-disorder fluctuations favoring a ground state which is different from
+the one selected by thermal fluctuations. The nonlinear terms are also shown to
+be crucial for a very strong near-resonant decay phenomenon leading to the
+quasiparticle breakdown in the kagom\'{e}-lattice antiferromagnets whose
+spectra are featuring flat or weakly dispersive modes. The effect is shown to
+persist even in the limit of large spin values and should be common to other
+frustrated magnets with flat branches of excitations. Model calculations of the
+spectrum of the $S=5/2$ Fe-jarosite with Dzyaloshinskii-Moriya anisotropy
+provide a convincing and detailed characterization of the proposed scenario.",1508.06632v2
+2015-09-01,Magnon-driven longitudinal spin Seebeck effect in F|N and N|F|N structures: role of asymmetric in-plane magnetic anisotropy,"The influence of an asymmetric in-plane magnetic anisotropy on the thermally
+activated spin current is studied theoretically for two different systems; (i)
+the system consisting of a ferromagnetic insulator in a direct contact with a
+nonmagnetic metal, and the sandwich structure consisting of a ferromagnetic
+insulating part sandwiched between two nonmagnetic metals. It is shown that
+when the difference between the temperatures of the two nonmagnetic metals in a
+structure is not large, the spin pumping currents from the magnetic part to the
+nonmagnetic ones are equal in amplitude and have opposite directions, so only
+the spin torque current contributes to the total spin current. The spin current
+flows then from the nonmagnetic metal with the higher temperature to the
+nonmagnetic metal having a lower temperature. Its amplitude varies linearly
+with the difference in temperatures. In addition, we have found that if the
+magnetic anisotropy is in the layer plane, then the spin current increases with
+the magnon temperature, while in the case of an out-of-plane magnetic
+anisotropy the spin current decreases when the magnon temperature enhances.
+Enlarging the difference between the temperatures of the nonmagnetic metals,
+the linear response becomes important, as confirmed by analytical expressions
+inferred from the Fokker-Planck approach and by the results obtained upon a
+full numerical integration of the stochastic Landau-Lifshitz-Gilbert equation.",1509.00376v1
+2015-10-08,Statistical anisotropy and cosmological quantum relaxation,"We show that cosmological quantum relaxation predicts an anisotropic
+primordial power spectrum with a specific dependence on wavenumber k. We
+explore some of the consequences for precision measurements of the cosmic
+microwave background (CMB). Quantum relaxation is a feature of the de
+Broglie-Bohm pilot-wave formulation of quantum theory, which allows the
+existence of more general physical states that violate the Born probability
+rule. Recent work has shown that relaxation to the Born rule is suppressed for
+long-wavelength field modes on expanding space, resulting in a large-scale
+power deficit with a characteristic inverse-tangent dependence on k. Because
+the quantum relaxation dynamics is independent of the direction of the wave
+vector for the relaxing field mode, in the limit of weak anisotropy we are able
+to derive an expression for the anisotropic power spectrum that is determined
+by the power deficit function. As a result, the off-diagonal terms in the CMB
+covariance matrix are also determined by the power deficit. We show that the
+lowest-order l-(l+1) inter-multipole correlations have a characteristic scaling
+with multipole moment l. Our derived spectrum also predicts a residual
+statistical anisotropy at small scales, with an approximate consistency
+relation between the scaling of the l-(l+1) correlations and the scaling of the
+angular power spectrum at high l. We also predict a relationship between the
+l-(l+1) correlations at large and small scales. Cosmological quantum relaxation
+appears to provide a single physical mechanism that predicts both a large-scale
+power deficit and a range of statistical anisotropies, together with
+potentially testable relationships between them.",1510.02523v1
+2015-12-28,Monolayer Molybdenum Disulfide Nanoribbons with High Optical Anisotropy,"Two-dimensional Molybdenum Disulfide (MoS2) has shown promising prospects for
+the next generation electronics and optoelectronics devices. The monolayer MoS2
+can be patterned into quasi-one-dimensional anisotropic MoS2 nanoribbons
+(MNRs), in which theoretical calculations have predicted novel properties.
+However, little work has been carried out in the experimental exploration of
+MNRs with a width of less than 20 nm where the geometrical confinement can lead
+to interesting phenomenon. Here, we prepared MNRs with width between 5 nm to 15
+nm by direct helium ion beam milling. High optical anisotropy of these MNRs is
+revealed by the systematic study of optical contrast and Raman spectroscopy.
+The Raman modes in MNRs show strong polarization dependence. Besides that the
+E' and A'1 peaks are broadened by the phonon-confinement effect, the modes
+corresponding to singularities of vibrational density of states are activated
+by edges. The peculiar polarization behavior of Raman modes can be explained by
+the anisotropy of light absorption in MNRs, which is evidenced by the polarized
+optical contrast. The study opens the possibility to explore
+quasione-dimensional materials with high optical anisotropy from isotropic 2D
+family of transition metal dichalcogenides.",1512.08338v1
+2016-02-04,Diverse anisotropy of phonon transport in two-dimensional IV-VI compounds: A comparative study,"New classes two-dimensional (2D) materials beyond graphene, including layered
+and non-layered, and their heterostructures, are currently attracting
+increasing interest due to their promising applications in nanoelectronics,
+optoelectronics and clean energy, where thermal transport property is one of
+the fundamental physical parameters. In this paper, we systematically
+investigated the phonon transport properties of 2D orthorhombic group IV-VI
+compounds of $GeS$, $GeSe$, $SnS$ and $SnSe$ by solving the Boltzmann transport
+equation (BTE) based on first-principles calculations. Despite the similar
+puckered (hinge-like) structure along the armchair direction as phosphorene,
+the four monolayer compounds possess diverse anisotropic properties in many
+aspects, such as phonon group velocity, Young's modulus and lattice thermal
+conductivity ($\kappa$), etc. Especially, the $\kappa$ along the zigzag and
+armchair directions of monolayer $GeS$ shows the strongest anisotropy while
+monolayer $SnS$ and $SnSe$ shows an almost isotropy in phonon transport. The
+origin of the diverse anisotropy is fully studied and the underlying mechanism
+is discussed in detail. With limited size, the $\kappa$ could be effectively
+lowered, and the anisotropy could be effectively modulated by nanostructuring,
+which would extend the applications in nanoscale thermoelectrics and thermal
+management. Our study offers fundamental understanding of the anisotropic
+phonon transport properties of 2D materials, and would be of significance for
+further study, modulation and aplications in emerging technologies.",1602.01766v2
+2016-03-07,Cyclotron maser emission from power-law electrons with strong pitch-angle anisotropy,"Energetic electrons with power-law spectrum are most commonly observed in
+astrophysics. This paper investigates electron cyclotron maser emission (ECME)
+from the power-law electrons, in which strong pitch-angle anisotropy is
+emphasized. The electron distribution function proposed in this paper can
+describe various types of pitch-angle anisotropy. Results show that the
+emission properties of ECME, including radiation growth, propagation, and
+frequency properties, depend considerably on the types of electron pitch-angle
+anisotropy, and different wave modes show different dependences on the pitch
+angle of electrons. In particular, the maximum growth rate of X2 mode rapidly
+decreases with respect to the electron pitch-angle cosine $\mu_0$ at which the
+electron distribution peaks, while the growth rates for other modes (X1, O1,
+O2) initially increase before decreasing as $\mu_0$ increases. Moreover, the O
+mode as well as the X mode can be the fastest growth mode, in terms of not only
+the plasma parameter but also the type of electron pitch-angle distribution.
+This result presents a significant extension of the recent researches on ECME
+driven by the lower-energy cutoff of power-law electrons, in which the X mode
+is generally the fastest growth mode.",1603.01923v1
+2016-03-10,ALICE overview,"Recent results from the ALICE experiment are presented with a particular
+emphasis on particle identification, the nuclear modification factor ($R_{AA}$)
+and azimuthal anisotropy ($v_2$). Comparison of lead-lead and proton-lead
+results reveals evidence of collectivity in small systems.",1603.03320v1
+2016-03-15,"Anisotropic, multi-carrier transport at the (111) LaAlO$_3$/SrTiO$_3$ interface","The conducting gas that forms at the interface between LaAlO$_3$ and
+SrTiO$_3$ has proven to be a fertile playground for a wide variety of physical
+phenomena. The bulk of previous research has focused on the (001) and (110)
+crystal orientations. Here we report detailed measurements of the
+low-temperature electrical properties of (111) LAO/STO interface samples. We
+find that the low-temperature electrical transport properties are highly
+anisotropic, in that they differ significantly along two mutually orthogonal
+crystal orientations at the interface. While anisotropy in the resistivity has
+been reported in some (001) samples and in (110) samples, the anisotropy in the
+(111) samples reported here is much stronger, and also manifests itself in the
+Hall coefficient as well as the capacitance. In addition, the anisotropy is not
+present at room temperature and at liquid nitrogen temperatures, but only at
+liquid helium temperatures and below. The anisotropy is accentuated by exposure
+to ultraviolet light, which disproportionately affects transport along one
+surface crystal direction. Furthermore, analysis of the low-temperature Hall
+coefficient and the capacitance as a function of back gate voltage indicates
+that in addition to electrons, holes contribute to the electrical transport.",1603.04538v2
+2016-04-29,Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy,"Astrophysical plasmas are typically magnetized, with the Larmor radii of the
+charged particles many orders of magnitude smaller than their collisional mean
+free paths. The fundamental properties of such plasmas, e.g., conduction and
+viscosity, may depend on the instabilities driven by the anisotropy of the
+particle distribution functions and operating at scales comparable to the
+Larmor scales. We discuss a possibility that the pressure anisotropy of thermal
+electrons could produce polarization of thermal bremsstrahlung emission. In
+particular, we consider coherent large-scale motions in galaxy clusters to
+estimate the level of anisotropy driven by stretching of the magnetic-field
+lines by plasma flow and by heat fluxes associated with thermal gradients. Our
+estimate of the degree of polarization is $\sim 0.1 \%$ at energies $\gtrsim
+kT$. While this value is too low for the forthcoming generation of X-ray
+polarimeters, it is potentially an important proxy for the processes taking
+place at extremely small scales, which are impossible to resolve spatially. The
+absence of the effect at the predicted level may set a lower limit on the
+electron collisionality in the ICM. At the same time, the small value of the
+effect implies that it does not preclude the use of clusters as (unpolarized)
+calibration sources for X-ray polarimeters at this level of accuracy.",1604.08669v2
+2016-05-06,Testing lowered isothermal models with direct N-body simulations of globular clusters,"Several self-consistent models have been proposed, aiming at describing the
+phase space distribution of stars in globular clusters. This study explores the
+ability of the recently proposed LIMEPY models (Gieles & Zocchi) to reproduce
+the dynamical properties of direct N-body models of a cluster in a tidal field,
+during its entire evolution. These dynamical models include prescriptions for
+the truncation and the degree of radially-biased anisotropy contained in the
+system, allowing us to explore the interplay between the role of anisotropy and
+tides in various stages of the life of star clusters. We show that the amount
+of anisotropy in an initially tidally underfilling cluster increases in the
+pre-collapse phase, and then decreases with time, due to the effect of the
+external tidal field on its spatial truncation. This is reflected in the
+correspondent model parameters, and the best-fit models reproduce the main
+properties of the cluster at all stages of its evolution, except for the phases
+immediately preceding and following core collapse. We also notice that the
+best-fit LIMEPY models are significantly different from isotropic King models,
+especially in the first part of the evolution of the cluster. Our results put
+limits on the amount of radial anisotropy that can be expected for clusters
+evolving in a tidal field, which is important to understand other factors that
+could give rise to similar observational signatures, such as the presence of an
+intermediate-mass black hole.",1605.02032v1
+2016-05-22,Low Gilbert damping in Co2FeSi and Fe2CoSi films,"Thin highly textured Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si ($0 \leq$ x
+$\leq 1$) films were prepared on MgO (001) substrates by magnetron
+co-sputtering. The magneto-optic Kerr effect (MOKE) and ferromagnetic resonance
+(FMR) measurements were used to investigate the composition dependence of the
+magnetization, the magnetic anisotropy, the gyromagnetic ratio and the
+relaxation of the films. The effective magnetization for the thin
+Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si films, determined by FMR measurements,
+are consistent with the Slater Pauling prediction. Both MOKE and FMR
+measurements reveal a pronounced fourfold anisotropy distribution for all
+films. In addition we found a strong influence of the stoichiometry on the
+anisotropy as the cubic anisotropy strongly increases with increasing Fe
+concentration. The gyromagnetic ratio is only weakly dependent on the
+composition. We find low Gilbert damping parameters for all films with values
+down to $0.0012\pm0.00012$ for Fe$_{1.75}$Co$_{1.25}$Si. The effective damping
+parameter for Co$_2$FeSi is found to be $0.0018\pm 0.0004$. We also find a
+pronounced anisotropic relaxation, which indicates significant contributions of
+two-magnon scattering processes that is strongest along the easy axes of the
+films. This makes thin Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si films ideal
+materials for the application in STT-MRAM devices.",1605.06797v1
+2016-06-01,Monte Carlo analysis for finite temperature magnetism of Nd$_2$Fe$_{14}$B permanent magnet,"We investigate the effects of magnetic inhomogeneities and thermal
+fluctuations on the magnetic properties of a rare earth intermetallic compound,
+Nd$_2$Fe$_{14}$B. The constrained Monte Carlo method is applied to a
+Nd$_2$Fe$_{14}$B bulk system to realize the experimentally observed spin
+reorientation and magnetic anisotropy constants $K^{\rm A}_m (m=1, 2, 4)$ at
+finite temperatures. % Subsequently, it is found that the temperature
+dependence of $K^{\rm A}_1$ deviates from the Callen--Callen law, $K^{\rm
+A}_1(T) \propto M(T)^3$, even above room temperature, $T_{\rm R}\sim 300\rm\,
+K$, when the Fe (Nd) anisotropy terms are removed to leave only the Nd (Fe)
+anisotropy terms. This is because the exchange couplings between Nd moments and
+Fe spins are much smaller than those between Fe spins. % It is also found that
+the exponent $n$ in the external magnetic field $H_{\rm ext}$ response of
+barrier height $\mathcal{F}_{\rm B}=\mathcal{F}_{\rm B}^0(1-H_{\rm ext}/H_0)^n$
+is less than $2$ in the low-temperature region below $T_{\rm R}$, whereas $n$
+approaches $2$ when $T>T_{\rm R}$, indicating the presence of
+Stoner--Wohlfarth-type magnetization rotation. This reflects the fact that the
+magnetic anisotropy is mainly governed by the $K^{\rm A}_1$ term in the
+$T>T_{\rm R}$ region.",1606.00333v2
+2016-06-27,Blume-Capel ferromagnet driven by propagating and standing magnetic field wave: Dynamical modes and nonequilibrium phase transition,"The dynamical responses of Blume-Capel (S=1) ferromagnet to the plane
+propagating (with fixed frequency and wavelength) and standing magnetic field
+waves are studied sepa- rately in two dimensions by extensive Monte Carlo
+simulation. Depending on the values of temperature, amplitude of the
+propagating magnetic field and the strength of anisotropy, two different
+dynamical phases are observed. For a fixed value of anisotropy and the
+amplitude of the propagating magnetic field, the system undergoes a dynamical
+phase transition from a driven spin wave propagating phase to a pinned or spin
+frozen state as the system is cooled down. The time averaged magnetisation over
+a full cycle of the propagating magnetic field plays the role of the dynamic
+order parameter. A comprehensive phase diagram is plotted in the plane formed
+by the amplitude of the propagating wave and the temperature of the system. It
+is found that the phase boundary shrinks inward as the anisotropy increases.
+The phase boundary, in the plane described by the strength of the anisotropy
+and temperature, is also drawn. This phase boundary was observed to shrink
+inward as the field amplitude increases.",1606.08155v3
+2016-07-26,Pseudospin anisotropy of trilayer semiconductor quantum Hall ferromagnets,"When two Landau levels are brought to a close coincidence between them and
+with the chemical potential in the Integer Quantum Hall regime, the two Landau
+levels can just cross or collapse while the external or pseudospin field that
+induces the alignment changes. In this work, all possible crossings are
+analyzed theoretically for the particular case of semiconductor trilayer
+systems, using a variational Hartree-Fock approximation. The model includes
+tunneling between neighboring layers, bias, intra-layer and inter-layer Coulomb
+interaction among the electrons. We have found that the general pseudospin
+anisotropy classification scheme used in bilayers applies also to the trilayer
+situation, with the simple crossing corresponding to an easy-axis ferromagnetic
+anisotropy analogy, and the collapse case corresponding to an easy-plane
+ferromagnetic analogy. An isotropic case is also possible, with the levels just
+crossing or collapsing depending on the filling factor and the quantum numbers
+of the two nearby levels. While our results are valid for any integer filling
+factor $\nu$ (=1,2,3,...), we have analyzed in detail the crossings at $\nu=3$
+and $4$, and we have given clear predictions that will help in their
+experimental search. In particular, the present calculations suggest that by
+increasing the bias, the trilayer system at these two filling factors can be
+driven from an easy-plane anisotropy regime to an easy-axis regime, and then
+can be driven back to the easy-plane regime. This kind of reentrant behavior is
+an unique feature of the trilayers, compared with the bilayers.",1607.07909v1
+2016-09-18,Cosmological constraints from the redshift dependence of the Alcock-Paczynski effect: application to the SDSS-III BOSS DR12 galaxies,"We apply the methodology developed in \cite{Li2014,Li2015} to BOSS DR12
+galaxies and derive cosmological constraints from the redshift dependence of
+the Alcock-Paczynski (AP) effect. The apparent anisotropy in the distribution
+of observed galaxies arise from two main sources, the redshift-space distortion
+(RSD) effect due to the galaxy peculiar velocities, and the geometric
+distortion when incorrect cosmological models are assumed for transforming
+redshift to comoving distance, known as the AP effect. Anisotropies produced by
+the RSD effect are, although large, maintaining a nearly uniform magnitude over
+a large range of redshift, while the degree of anisotropies from the AP effect
+varies with redshift by much larger magnitude. We split the DR12 galaxies into
+six redshift bins, measure the 2-point correlation function in each bin, and
+assess the redshift evolution of anisotropies. We obtain constraints of
+$\Omega_m=0.290 \pm 0.053,\ \ w = -1.07 \pm 0.15$, which are comparable with
+the current constraints from other cosmological probes such as type Ia
+supernovae, cosmic microwave background, and baryon acoustic oscillation (BAO).
+Combining these cosmological probes with our method yield tight constraints of
+$ \Omega_m = 0.301 \pm 0.006,\ w=-1.054 \pm 0.025$. Our method is complementary
+to the other large scale structure probes like BAO and topology. We expect this
+technique will play an important role in deriving cosmological constraints from
+large scale structure surveys.",1609.05476v1
+2016-09-25,Effects of anisotropy and Coulomb interactions on quantum transport in a quadruple quantum-dot structure,"We present analytical and numerical investigation of spectral and transport
+properties of a quadruple quantum-dot (QQD) structure which is one of the
+popular low-dimensional systems in the context of fundamental quantum physics
+study, future electronic applications and quantum calculations. The density of
+states, occupation numbers and conductance of the structure were analyzed using
+the nonequilibrium Green's functions in the tight binding approach and the
+equation-of-motion method. In particular the anisotropy of hopping integrals
+and on-site electron energies as well as the effects of the finite intra- and
+interdot Coulomb interactions were investigated. It was found out that the
+anisotropy of the kinetic processes in the system leads to the Fano-Feshbach
+asymmetrical peak. We demonstrated that the conductance of QQD device has a
+wide insulating band with steep edges separating triple-peak structures if the
+intradot Coulomb interactions are taken into account. The interdot Coulomb
+correlations between the central QDs result in the broadening of this band and
+the occurrence of an additional band with low conductance due to the Fano
+antiresonances. It was shown that in this case the conductance of the
+anisotropic QQD device can be dramatically changed by tuning the anisotropy of
+on-site electron energies.",1609.07760v1
+2016-10-17,Can we reconcile the TA excess and hotspot with Auger observations?,"The Telescope Array (TA) shows a 20$^{\circ}$ hotspot as well as an excess of
+UHECRs above 50~EeV when compared with the Auger spectrum. We consider the
+possibility that both the TA excess and hotspot are due to a dominant source in
+the Northern sky. We carry out detailed simulations of UHECR propagation in
+both the intergalactic medium and the Galaxy, using different values for the
+intergalactic magnetic field. We consider two general classes of sources:
+transients and steady, adopting a mixed UHECR composition that is consistent
+with the one found by Auger. The spatial location of the sources is draw
+randomly. We generate Auger-like and TA-like data sets from which we determine
+the spectrum, the sky maps and the level of anisotropy. We find that, while
+steady sources are favored over transients, it is unlikely to account for all
+the currently available observational data. While we reproduce fairly well the
+Auger spectrum for the vast majority of the simulated data sets, most of the
+simulated data sets with a spectrum compatible with that of TA (at most a few
+percent depending on density model tested) show a much stronger anisotropy than
+the one observed. We find that the rare cases in which both the spectrum and
+the anisotropy are consistent require a steady source within $\sim 10$ Mpc, to
+account for the flux excess, and a strong extragalactic magnetic field $\sim
+10$ nG, to reduce the excessive anisotropy.",1610.05319v2
+2016-12-23,Testing parity-violating physics from cosmic rotation power reconstruction,"We study the reconstruction of the cosmic rotation power spectrum produced by
+parity-violating physics, with an eye to ongoing and near future cosmic
+microwave background (CMB) experiments such as BICEP Array, CMBS4, LiteBIRD and
+Simons Observatory. In addition to the inflationary gravitational waves and
+gravitational lensing, measurements of other various effects on CMB
+polarization open new window into the early Universe. One of these is
+anisotropies of the cosmic polarization rotation which probes the Chern-Simons
+term generally predicted by string theory. The anisotropies of the cosmic
+rotation are also generated by the primordial magnetism and in the Standard
+Model extention framework. The cosmic rotation anisotropies can be
+reconstructed as quadratic in CMB anisotropies. However, the power of the
+reconstructed cosmic rotation is a CMB four-point correlation and is not
+directly related to the cosmic-rotation power spectrum. Understanding all
+contributions in the four-point correlation is required to extract the cosmic
+rotation signal. Assuming a scale-invariant rotation spectrum motivated by the
+inflationary cosmic-rotation models, we employ simulation to quantify each
+contribution to the four-point correlation and find that (1) a secondary
+contraction of the trispectrum increases the total signal-to-noise, (2) a bias
+from the lensing-induced trispectrum is significant compared to the statistical
+errors in, e.g., LiteBIRD and CMBS4-like experiments, (3) the use of a
+realization-dependent estimator decreases the statistical errors by 10%-20%,
+depending on experimental specifications, and (4) other higher-order
+contributions are negligible at least for near future experiments.",1612.07855v3
+2017-03-03,A nonlinear Monte Carlo model of super-diffusive shock acceleration with magnetic field amplification,"Fast collisionless shocks in cosmic plasmas convert their kinetic energy flow
+into the hot downstream thermal plasma with a substantial fraction of energy
+going into a broad spectrum of superthermal charged particles and magnetic
+fluctuations. The superthermal particles can penetrate into the shock upstream
+region producing an extended shock precursor. The cold upstream plasma flow is
+decelerated by the force provided by the superthermal particle pressure
+gradient. In high Mach number collisionless shocks, efficient particle
+acceleration is likely coupled with turbulent magnetic field amplification
+(MFA) generated by the anisotropic distribution of accelerated particles. This
+anisotropy is determined by the fast particle transport making the problem
+strongly nonlinear and multi-scale. Here, we present a nonlinear Monte Carlo
+model of collisionless shock structure with super-diffusive propagation of
+high-energy Fermi accelerated particles coupled to particle acceleration and
+MFA which affords a consistent description of strong shocks. A distinctive
+feature of the Monte Carlo technique is that it includes the full angular
+anisotropy of the particle distribution at all precursor positions. The model
+reveals that the super-diffusive transport of energetic particles (i.e.,
+Levy-walk propagation) generates a strong quadruple anisotropy in the precursor
+particle distribution. The resultant pressure anisotropy of the high-energy
+particles produces a non-resonant mirror-type instability which amplifies
+compressible wave modes with wavelengths longer than the gyroradii of the
+highest energy protons produced by the shock.",1703.01160v2
+2017-03-24,Effects of anisotropy in spin molecular-orbital coupling on effective spin models of trinuclear organometallic complexes,"We consider layered decorated honeycomb lattices at two-thirds filling, as
+realized in some trinuclear organometallic complexes. Localized $S=1$ moments
+with a single-spin anisotropy emerge from the interplay of Coulomb repulsion
+and spin molecular-orbit coupling (SMOC). Magnetic anisotropies with bond
+dependent exchange couplings occur in the honeycomb layers when the direct
+intracluster exchange and the spin molecular-orbital coupling are both present.
+We find that the effective spin exchange model within the layers is an XXZ +
+120$^\circ$ honeycomb quantum compass model. The intrinsic non-spherical
+symmetry of the multinuclear complexes leads to very different transverse and
+longitudinal spin molecular-orbital couplings, which greatly enhances the
+single-spin and exchange coupling anisotropies. The interlayer coupling is
+described by a XXZ model with anisotropic biquadratic terms. As the correlation
+strength increases the systems becomes increasingly one-dimensional. Thus, if
+the ratio of SMOC to the interlayer hopping is small this stabilizes the
+Haldane phase. However, as the ratio increases there is a quantum phase
+transition to the topologically trivial `$D$-phase'. We also predict a quantum
+phase transition from a Haldane phase to a magnetically ordered phase at
+sufficiently strong external magnetic fields.",1703.08343v3
+2017-03-30,Anisotropy governed competition of magnetic phases in the honeycomb quantum magnet Na$_3$Ni$_2$SbO$_6$ studied by dilatometry and high-frequency ESR,"Thermodynamic properties as well as low-energy magnon excitations of $S=1$
+honeycomb-layered Na$_3$Ni$_2$SbO$_6$ have been investigated by high-resolution
+dilatometry, static magnetisation, and high-frequency electron spin resonance
+studies in magnetic fields up to 16 T. At $T_{\rm N}$ = 16.5 K, there is a
+tricritical point separating two distinct antiferromagnetic phases AF1 and AF2
+from the paramagnetic regime. In addition, our data imply short-range
+antiferromagnetic correlations at least up to $\sim 5\cdot T_{\rm N}$. Well
+below $T_{\rm N}$, the magnetic field $B_{\rm C1}\approx$ 9.5 T is needed to
+stabilize AF2 against AF1. The thermal expansion and magnetostriction anomalies
+at $T_{\rm N}$ and $B_{\rm C1}$ imply significant magnetoelastic coupling, both
+of which associated with a sign change of $\partial L/\partial B$. The
+transition at $B_{\rm C1}$ is associated with softening of the
+antiferromagnetic resonance modes observed in the electron spin resonance
+spectra. The anisotropy gap $\Delta = 360$ GHz implies considerable uniaxial
+anisotropy. We conclude the crucial role of axial anisotropy favoring the AF1
+spin structure over the AF2 one. While the magnetostriction data disprove a
+simple spin-flop scenario at $B_{\rm C1}$, the nature of a second transition at
+$B_{\rm C2}\approx$ 13 T remains unclear. Both the sign of the magnetostriction
+and Gr\""uneisen analysis suggest the short-range correlations at high
+temperatures to be of AF2-type.",1703.10493v1
+2017-04-22,Dark Energy Induced Anisotropy in Cosmic Expansion,"In order to understand the nature of the accelerating expansion of the
+late-time universe, it is important to experimentally determine whether dark
+energy is a cosmological constant or dynamical in nature. If dark energy
+already exists prior to inflation, which is a reasonable assumption, then one
+expects that a dynamical dark energy would leave some footprint in the
+anisotropy of the late-time accelerated expansion. To demonstrate the viability
+of this notion, we invoke the quintessence field with the exponential potential
+as one of the simplest dynamical dark energy models allowed by observations. We
+investigate the effects of its quantum fluctuations (the physical origin of the
+perturbation being isocurvature) generated during inflation and having fully
+positive correlation with the primordial curvature perturbations, and estimate
+the anisotropy of the cosmic expansion so induced. We show that the primordial
+amplitude of quantum fluctuations of quintessence field {\delta\phi}_P can be
+related to the tensor-to-scalar ratio r, and we calculate the perturbed
+luminosity distance to first order and the associated luminosity distance power
+spectrum, which is an estimator of anisotropicity of late-time accelerated
+expansion. We find that the gravitational potential at large scales and late
+times is less decayed in QCDM compared to that in {\Lambda}CDM so that the
+smaller the redshift and multipole, the more relative deficit of power in QCDM.
+Our results of luminosity distance power spectrum also show the similar
+conclusions of suppression as that of the previous investigation regarding the
+effect of quantum fluctuations of quintessence field on the CMB temperature
+anisotropies.",1704.06797v2
+2017-05-03,Quantum phase transitions driven by rhombic-type single-ion anisotropy in the S=1 Haldane chain,"The spin-1 Haldane chain is an example of the symmetry-protected-topological
+(SPT) phase in one dimension. Experimental realization of the spin chain
+materials usually involves both the uniaxial-type, $D(S^z)^2$, and the
+rhombic-type, $E[(S^x)^2-(S^y)^2]$, single-ion anisotropies. Here, we provide a
+precise ground-state phase diagram for spin-1 Haldane chain with these
+single-ion anisotropies. Using quantum numbers, we find that the $\mathbb{Z}_2$
+symmetry breaking phase can be characterized by double degeneracy in the
+entanglement spectrum. Topological quantum phase transitions take place on
+particular paths in the phase diagram, from the Haldane phase to the
+Large-$E_x$, Large-$E_y$, or Large-$D$ phases. The topological critical points
+are determined by the level spectroscopy method with a newly developed parity
+technique in the density matrix renormalization group [Phys. Rev. B 86, 024403
+(2012)], and the Haldane-Large-$D$ critical point is obtained with an
+unprecedentedly precision, $(D/J)_c=0.9684713(1)$. Close to this critical
+point, a small rhombic single-ion anisotropy $|E|/J\ll1$ can destroy the
+Haldane phase and bring the system into a $y$-N\'eel phase. We propose that the
+compound [Ni(HF$_2$)(3-Clpy)$_4$]BF$_4$ is a candidate system to search for the
+$y$-N\'eel phase.",1705.01558v2
+2017-05-18,Magnetization dynamics and its scattering mechanism in thin CoFeB films with interfacial anisotropy,"Studies of magnetization dynamics have incessantly facilitated the discovery
+of fundamentally novel physical phenomena, making steady headway in the
+development of magnetic and spintronics devices. The dynamics can be induced
+and detected electrically, offering new functionalities in advanced electronics
+at the nanoscale. However, its scattering mechanism is still disputed.
+Understanding the mechanism in thin films is especially important, because most
+spintronics devices are made from stacks of multilayers with nanometer
+thickness. The stacks are known to possess interfacial magnetic anisotropy, a
+central property for applications, whose influence on the dynamics remains
+unknown. Here, we investigate the impact of interfacial anisotropy by adopting
+CoFeB/MgO as a model system. Through systematic and complementary measurements
+of ferromagnetic resonance (FMR), on a series of thin films, we identify
+narrower FMR linewidths at higher temperatures. We explicitly rule out the
+temperature dependence of intrinsic damping as a possible cause, and it is also
+not expected from existing extrinsic scattering mechanisms for ferromagnets. We
+ascribe this observation to motional narrowing, an old concept so far neglected
+in the analyses of FMR spectra. The effect is confirmed to originate from
+interfacial anisotropy, impacting the practical technology of spin-based
+nanodevices up to room temperature.",1705.06624v1
+2017-05-14,Prediction of plastic anisotropy of textured polycrystalline sheets based on a new single crystal model,"In this paper, we predict the effect of texture on the anisotropy in plastic
+properties of polycrystalline metallic sheets. The constituent grain behavior
+is modelled using the new single crystal yield criterion developed by Cazacu,
+Revil, and Chandola (2017). For ideal texture components, the yield stress and
+plastic strain ratios can be obtained analytically. For the case of strongly
+textured sheets containing a spread about the ideal texture components, the
+polycrystalline response is obtained numerically on the basis of the same
+single-crystal criterion. It is shown that for textures with misorientation
+scatter width up to 25 degrees, the numerical predictions are very close to
+those obtained analytically for an ideal texture. Furthermore, irrespective of
+the number of grains in the sample, Lankford coefficients have finite values
+for all loading orientations. Illustrative examples for sheets with textures
+containing a combination of few ideal texture components are also presented.
+The simulations of the predicted polycrystalline behavior based on the new
+description of the plastic behavior of the constituent grains capture the
+influence of individual texture components on the overall degree of anisotropy.
+The polycrystalline simulation results are also compared to analytical
+estimates obtained using the closed-form formulas for the ideal components
+present in the texture in conjunction with a simple law of mixtures. The
+analytical estimates show the same trends as the simulation results. Therefore,
+the trends in plastic anisotropy of the macroscopic properties can be
+adequately estimated analytically.",1705.10018v1
+2017-06-29,Island dynamics and anisotropy during vapor phase epitaxy of m-plane GaN,"Using in situ grazing-incidence x-ray scattering, we have measured the
+diffuse scattering from islands that form during layer-by-layer growth of GaN
+by metal-organic vapor phase epitaxy on the (1010) m-plane surface. The diffuse
+scattering is extended in the (0001) in-plane direction in reciprocal space,
+indicating a strong anisotropy with islands elongated along [1 $\overline{2}$
+10] and closely spaced along [0001]. This is confirmed by atomic force
+microscopy of a quenched sample. Islands were characterized as a function of
+growth rate G and temperature. The island spacing along [0001] observed during
+the growth of the first monolayer obeys a power-law dependence on growth rate
+G$^{-n}$, with an exponent $n = 0.25 \pm 0.02$. Results are in agreement with
+recent kinetic Monte Carlo simulations, indicating that elongated islands
+result from the dominant anisotropy in step edge energy and not from surface
+diffusion anisotropy. The observed power-law exponent can be explained using a
+simple steady-state model, which gives n = 1/4.",1706.09955v1
+2017-07-04,Can we reconcile the TA excess and hotspot with Auger observations?,"The Telescope Array (TA) shows a 20$^{\circ}$ hotspot as well as an excess of
+UHECRs above 50~EeV when compared with the Auger spectrum. We consider the
+possibility that both the TA excess and hotspot are due to a dominant source in
+the Northern sky. We carry out detailed simulations of UHECR propagation in
+both the intergalactic medium and the Galaxy, using different values for the
+intergalactic magnetic field. We consider two general classes of sources:
+transients and steady, adopting a mixed UHECR composition that is consistent
+with the one found by Auger. The spatial location of the sources is draw
+randomly. We generate Auger-like and TA-like data sets from which we determine
+the spectrum, the sky maps and the level of anisotropy. We find that, while
+steady sources are favored over transients, it is unlikely to account for all
+the currently available observational data. While we reproduce fairly well the
+Auger spectrum for the vast majority of the simulated data sets, most of the
+simulated data sets with a spectrum compatible with that of TA (at most a few
+percent depending on density model tested) show a much stronger anisotropy than
+the one observed. We find that the rare cases in which both the spectrum and
+the anisotropy are consistent require a steady source within $\sim 10$ Mpc, to
+account for the flux excess, and a strong extragalactic magnetic field $\sim
+10$ nG, to reduce the excessive anisotropy.",1707.01177v2
+2017-07-10,The Kinematic Richness of Star Clusters I. Isolated Spherical Models with Primordial Anisotropy,"We investigate the dynamical evolution of isolated equal-mass star cluster
+models by means of direct N-body simulations, primarily focusing on the effects
+of the presence of primordial anisotropy in the velocity space. We found
+evidence of the existence of a monotonic relationship between the moment of
+core collapse and the amount and flavour of anisotropy in the stellar system.
+Specifically, equilibria characterised by the same initial structural
+properties (Plummer density profile) and with different degrees of
+tangentially-biased (radially-biased) anisotropy, reach core collapse earlier
+(later) than isotropic models. We interpret this result in light of an
+accelerated (delayed) phase of the early evolution of collisional stellar
+systems ""anisotropic-response""), which we have characterised both in terms of
+the evolution of the velocity moments and of a fluid model of two-body
+relaxation. For the case of the most tangentially anisotropic model the initial
+phase of evolution involves a catastrophic collapse of the inner part of the
+system which continues until an isotropic velocity distribution is reached.
+This study represents a first step towards a comprehensive investigation of the
+role played by kinematic richness in the long-term dynamical evolution of
+collisional systems.",1707.02792v1
+2017-07-11,Planck 2015 constraints on the non-flat $Λ$CDM inflation model,"We study Planck 2015 cosmic microwave background (CMB) anisotropy data using
+the energy density inhomogeneity power spectrum generated by quantum
+fluctuations during an early epoch of inflation in the non-flat $\Lambda$CDM
+model. Unlike earlier analyses of non-flat models, which assumed an
+inconsistent power-law power spectrum of energy density inhomogeneities, we
+find that the Planck 2015 data alone, and also in conjunction with baryon
+acoustic oscillation measurements, are reasonably well fit by a closed
+$\Lambda$CDM model in which spatial curvature contributes a few percent of the
+current cosmological energy density budget. In this model, the measured Hubble
+constant and non-relativistic matter density parameter are in good agreement
+with values determined using most other data. Depending on parameter values,
+the closed $\Lambda$CDM model has reduced power, relative to the tilted,
+spatially-flat $\Lambda$CDM case, and can partially alleviate the low multipole
+CMB temperature anisotropy deficit and can help partially reconcile the CMB
+anisotropy and weak lensing $\sigma_8$ constraints, at the expense of somewhat
+worsening the fit to higher multipole CMB temperature anisotropy data. Our
+results are interesting but tentative; a more thorough analysis is needed to
+properly gauge their significance.",1707.03452v2
+2017-07-16,First Principles Study of the Giant Magnetic Anisotropy Energy in Bulk Na4IrO4,"In 5d transition metal oxides, novel properties arise from the interplay of
+electron correlations and spin--orbit interactions. Na4IrO4, where 5d
+transition-metal Ir atom occupies the center of the square-planar coordination
+environment, is synthesized. Based on density functional theory, we calculate
+its electronic and magnetic properties. Our numerical results show that the
+Ir-5d bands are quite narrow, and the bands around the Fermi level are mainly
+contributed by d_{xy},d_{yz} and d_{zx} orbitals. The magnetic easy-axis is
+perpendicular to the IrO4 plane, and the magnetic anisotropy energy (MAE) of
+Na4IrO4 is found to be very giant. We estimate the magnetic parameters by
+mapping the calculated total energy for different spin configurations onto a
+spin model. The next nearest neighbor exchange interaction J2 is much larger
+than other intersite exchange interactions and results in the magnetic ground
+state configuration. Our study clearly demonstrates that the huge MAE comes
+from the single-ion anisotropy rather than the anisotropic interatomic spin
+exchange. This compound has a large spin gap but very narrow spin-wave
+dispersion, due to the large single-ion anisotropy and relatively small
+exchange couplings. Noticing this remarkable magnetic feature originated from
+its highly isolated IrO4 moiety, we also explore the possiblity to further
+enhance the MAE.",1707.04865v1
+2017-07-27,Two-component Jaffe models with a central black hole. I: the spherical case,"Dynamical properties of spherically symmetric galaxy models where both the
+stellar and total mass density distributions are described by the Jaffe (1983)
+profile (with different scale-lenghts and masses), are presented. The orbital
+structure of the stellar component is described by Osipkov--Merritt anisotropy,
+and a black hole (BH) is added at the center of the galaxy; the dark matter
+halo is isotropic. First, the conditions required to have a nowhere negative
+and monothonically decreasing dark matter halo density profile, are derived. We
+then show that the phase-space distribution function can be recovered by using
+the Lambert-Euler $W$ function, while in absence of the central BH only
+elementary functions appears in the integrand of the inversion formula. The
+minimum value of the anisotropy radius for consistency is derived in terms of
+the galaxy parameters. The Jeans equations for the stellar component are solved
+analytically, and the projected velocity dispersion at the center and at large
+radii are also obtained analytically for generic values of the anisotropy
+radius. Finally, the relevant global quantities entering the Virial Theorem are
+computed analytically, and the fiducial anisotropy limit required to prevent
+the onset of Radial Orbit Instability is determined as a function of the galaxy
+parameters. The presented models, even though highly idealized, represent a
+substantial generalization of the models presentd in Ciotti et al. (2009), and
+can be useful as starting point for more advanced modeling the dynamics and the
+mass distribution of elliptical galaxies.",1707.08822v2
+2017-08-03,Evolution of the interfacial perpendicular magnetic anisotropy constant of the Co$_2$FeAl/MgO interface upon annealing,"We investigate thickness series of films of the Heusler alloy Co$_2$FeAl in
+order to study the effect of annealing on the interface with a MgO layer and on
+the bulk magnetic properties. Our results reveal that while the perpendicular
+interface anisotropy constant $K^{\perp}_{\rm S}$ is zero for the as-deposited
+samples, its value increases with annealing up to a value of $1.14\, \pm
+\,0.07$~mJ/m$^2$ for the series annealed at 320$^{\rm o}$C and of $2.07\, \pm
+\,0.7$~mJ/m$^2$ for the 450$^{\rm o}$C annealed series owing to a strong
+modification of the interface during the thermal treatment. This large value
+ensures a stabilization of a perpendicular magnetization orientation for a
+thickness below 1.7~nm. The data additionally shows that the in-plane biaxial
+anisotropy constant has a different evolution with thickness in as-deposited
+and annealed systems. The Gilbert damping parameter $\alpha$ shows minima for
+all series for a thickness of 40~nm and an absolute minimum value of
+$2.8\pm0.1\cdot10^{-3}$. The thickness dependence is explained in terms of an
+inhomogenous magnetization state generated by the interplay between the
+different anisotropies of the system and by crystalline disorder.",1708.01126v2
+2017-08-09,Combined Analysis of Cosmic-Ray Anisotropy with IceCube and HAWC,"During the past two decades, experiments in both the northern and southern
+hemispheres have observed a small but measurable energy-dependent sidereal
+anisotropy in the arrival direction distribution of Galactic cosmic rays with
+relative intensities at the level of one per mille. Individually, these
+measurements are restricted by limited sky coverage, and so the power spectrum
+of the anisotropy obtained from any one measurement displays a systematic
+correlation between different multipole modes $C_\ell$. We present the results
+of a joint analysis of the anisotropy on all angular scales using cosmic-ray
+data collected during 336 days of operation of the High-Altitude Water
+Cherenkov (HAWC) Observatory (located at 19$^\circ$ N) and 5 years of data
+taking from the IceCube Neutrino Observatory (located at 90$^\circ$ S) The
+results include a combined sky map and an all-sky power spectrum in the
+overlapping energy range of the two experiments at around 10 TeV. We describe
+the methods used to combine the IceCube and HAWC data, address the individual
+detector systematics, and study the region of overlapping field of view between
+the two observatories.",1708.03005v1
+2017-08-21,Crossover from low-temperature to high-temperature fluctuations. II. Nonuniversal thermodynamic Casimir forces of anisotropic systems,"The finite-size renormalization-group approach for isotropic O$(n)$-symmetric
+systems introduced previously [V. Dohm, Phys. Rev. Lett. {\bf 110}, 107207
+(2013)] is extended to weakly anisotropic O$(n)$-symmetric systems. Our theory
+is formulated within the $\varphi^4$ model with lattice anisotropy in a
+$d$-dimensional block geometry with periodic boundary conditions. It describes
+the crossover from low- to high-temperature fluctuations including
+Goldstone-dominated and critical fluctuations for $1\leq n \leq \infty$ in
+$2<d<4$ dimensions. An exact representation is derived for the large-distance
+behavior of the bulk correlation function of anisotropic systems in terms of
+the principal correlation lengths and an anisotropy matrix ${\bf \bar A}$. This
+includes the long-ranged correlations with an anisotropic algebraic decay at
+low temperatures due to the Goldstone modes for $n>1$. We calculate the
+finite-size scaling functions of the excess free energy and thermodynamic
+Casimir force. Exact results are derived in the large-$n$ limit. Applications
+are given for $L_\parallel^{d-1} \times L$ slab geometries with a finite aspect
+ratio $\rho=L/L_\parallel$ as well as for the film limit $\rho \to 0$. For
+weakly anisotropic systems two-scale-factor universality is replaced by
+multiparameter universality. This implies a substantial reduction of the
+predictive power of bulk and finite-size theory for anisotropic systems as
+compared to isotropic systems. The validity of multiparameter universality is
+confirmed analytically for a nontrivial example of the $d=2,n=1$ universality
+class. Anisotropy-dependent minima of the Casimir force scaling function are
+found below $T_c$. Both the sign and magnitude of the Casimir amplitude in the
+Goldstone and critical regimes are affected by the lattice anisotropy.
+Quantitative predictions are made that can be tested by Monte Carlo
+simulations.",1708.06272v1
+2017-08-29,Probing the chiral magnetic wave in pPb and PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV using charge-dependent azimuthal anisotropies,"Charge-dependent anisotropy Fourier coefficients ($v_n$) of particle
+azimuthal distributions are measured in pPb and PbPb collisions at $
+\sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV with the CMS detector at the
+LHC. The normalized difference in the second-order anisotropy coefficients
+($v_2$) between positively and negatively charged particles is found to depend
+linearly on the observed event charge asymmetry with comparable slopes for both
+pPb and PbPb collisions over a wide range of charged particle multiplicity. In
+PbPb, the third-order anisotropy coefficient, $v_3$, shows a similar linear
+dependence with the same slope as seen for $v_2$. The observed similarities
+between the $v_2$ slopes for pPb and PbPb, as well as the similar slopes for
+$v_2$ and $v_3$ in PbPb, are compatible with expectations based on local charge
+conservation in the decay of clusters or resonances, and constitute a challenge
+to the hypothesis that, at LHC energies, the observed charge asymmetry
+dependence of $v_2$ in heavy ion collisions arises from a chiral magnetic wave.",1708.08901v2
+2017-08-30,The effect of non-sphericity on mass and anisotropy measurements in dSph galaxies with Schwarzschild method,"In our previous work we confirmed the reliability of the spherically
+symmetric Schwarzschild orbit-superposition method to recover the mass and
+velocity anisotropy profiles of spherical dwarf galaxies. Here we investigate
+the effect of its application to intrinsically non-spherical objects. For this
+purpose we use a model of a dwarf spheroidal galaxy formed in a numerical
+simulation of a major merger of two disky dwarfs. The shape of the stellar
+component of the merger remnant is axisymmetric and prolate which allows us to
+identify and measure the bias caused by observing the spheroidal galaxy along
+different directions, especially the longest and shortest principal axis. The
+modelling is based on mock data generated from the remnant that are
+observationally available for dwarfs: projected positions and line-of-sight
+velocities of the stars. In order to obtain a reliable tool while keeping the
+number of parameters low we parametrize the total mass distribution as a
+radius-dependent mass-to-light ratio with just two free parameters we aim to
+constrain. Our study shows that if the total density profile is known, the
+true, radially increasing anisotropy profile can be well recovered for the
+observations along the longest axis whereas the data along the shortest axis
+lead to the inference an incorrect, isotropic model. On the other hand, if the
+density profile is derived from the method as well, the anisotropy is always
+underestimated but the total mass profile is well recovered for the data along
+the shortest axis whereas for the longest axis the mass content is
+overestimated.",1708.09425v2
+2017-09-25,Is perpendicular magnetic anisotropy essential to all-optical ultrafast spin reversal in ferromagnets?,"All-optical spin reversal presents a new opportunity for spin manipulations,
+free of a magnetic field. Most of all-optical-spin-reversal ferromagnets are
+found to have a perpendicular magnetic anisotropy (PMA), but it has been
+unknown whether PMA is necessary for the spin reversal. Here we theoretically
+investigate magnetic thin films with either PMA or in-plane magnetic anisotropy
+(IMA). Our results show that the spin reversal in IMA systems is possible, but
+only with a longer laser pulse and within a narrow laser parameter region. The
+spin reversal does not show a strong helicity dependence where the left- and
+right-circularly polarized light lead to the identical results. By contrast,
+the spin reversal in PMA systems is robust, provided both the spin angular
+momentum and laser field are strong enough while the magnetic anisotropy itself
+is not too strong. This explains why experimentally the majority of all-optical
+spin-reversal samples are found to have strong PMA and why spins in Fe
+nanoparticles only cant out of plane. It is the laser-induced spin-orbit torque
+that plays a key role in the spin reversal. Surprisingly, the same spin-orbit
+torque results in laser-induced spin rectification in spin-mixed configuration,
+a prediction that can be tested experimentally. Our results clearly point out
+that PMA is essential to the spin reversal, though there is an opportunity for
+in-plane spin reversal.",1709.08690v1
+2017-09-30,Multi-Scale Pipeline for the Search of String-Induced CMB Anisotropies,"We propose a multi-scale edge-detection algorithm to search for the
+Gott-Kaiser-Stebbins imprints of a cosmic string (CS) network on the Cosmic
+Microwave Background (CMB) anisotropies. Curvelet decomposition and extended
+Canny algorithm are used to enhance the string detectability. Various
+statistical tools are then applied to quantify the deviation of CMB maps having
+a cosmic string contribution with respect to pure Gaussian anisotropies of
+inflationary origin. These statistical measures include the one-point
+probability density function, the weighted two-point correlation function
+(TPCF) of the anisotropies, the unweighted TPCF of the peaks and of the
+up-crossing map, as well as their cross-correlation. We use this algorithm on a
+hundred of simulated Nambu-Goto CMB flat sky maps, covering approximately
+$10\%$ of the sky, and for different string tensions $G\mu$. On noiseless sky
+maps with an angular resolution of $0.9'$, we show that our pipeline detects
+CSs with $G\mu$ as low as $G\mu\gtrsim 4.3\times 10^{-10}$. At the same
+resolution, but with a noise level typical to a CMB-S4 phase II experiment, the
+detection threshold would be to $G\mu\gtrsim 1.2 \times 10^{-7}$.",1710.00173v1
+2017-10-03,Fission Fragment Angular Anisotropy in Neutron-Induced Fission of $^{235}$U Measured with a Time Projection Chamber,"Fission fragment angular distributions can provide an important constraint on
+fission theory, improving predictive fission codes, and are a prerequisite for
+a precise ratio cross section measurement. Available anisotropy data is sparse,
+especially at neutron energies above 5 MeV. For the first time, a
+three-dimensional tracking detector is employed to study fragment emission
+angles and provide a direct measurement of angular anisotropy. The Neutron
+Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has
+deployed the fission time projection chamber (fissionTPC) to measure nuclear
+data with unprecedented precision. The fission fragment anisotropy of $^{235}$U
+has been measured over a wide range of incident neutron energies from 180 keV
+to 200 MeV; a careful study of the systematic uncertainties complement the
+data.",1710.00973v2
+2017-10-21,"Size dependence of the effective magnetic anisotropy in Co, Ni, Fe, and magnetite nanoparticles: Testing the core-shell-surface-layer (CSSL) model","The stability of the stored information in recording media depends on the
+anisotropy energy Ea = KeffV of nanoparticles (NPs) of volume V or diameter D.
+Therefore, the knowledge of how the effective magnetic anisotropy Keff varies
+with D for a given system is important for technological applications. In a
+recent paper [Appl. Phys. Lett. 110 (22), 222409 (2017)], the variation of Keff
+versus D in NPs of maghemite ({\gamma}-Fe2O3) was best described by the Eq.:
+Keff = Kb + (6KS/D) +Ksh{[1-(2d/D)]-3 -1}, where Kb, KS, and Ksh are the
+anisotropy constants of spins in the core, surface layer, and a shell of
+thickness d, respectively. This core-shell-surface layer (CSSL) model is an
+extension of the often used core-surface layer (CSL) model described by Keff =
+Kb + (6KS/D) [Phys. Rev. Lett. 72, 282 (1994)]. The additional term involving
+Ksh was found to be necessary to fit the data for smaller NPs of {\gamma}-Fe2O3
+with D < 5 nm. Here we check the validity of the CSSL model for metallic
+magnetic NPs of Co, Ni, Fe and magnetite using Keff vs. D data from published
+literature. Care was taken in selecting data only for those NPs for which the
+effects of interparticle interactions has been taken into account in
+determining Keff. The importance of the new CSSL model is that it describes
+well the Keff vs. D variation for all particles sizes whereas the core-surface
+layer model often fails for smaller particles with the notable exception of Fe
+NPs. The verification of the CSSL model for metallic NPs of Co, Ni, and
+magnetite along with NPs of NiO and {\gamma}-Fe2O3 validates its general
+applicability.",1710.07832v1
+2017-10-27,Azimuthal Anisotropy in High Energy Nuclear Collision - An Approach based on Complex Network Analysis,"Recently, a complex network based method of Visibility Graph has been applied
+to confirm the scale-freeness and presence of fractal properties in the process
+of multiplicity fluctuation. Analysis of data obtained from experiments on
+hadron-nucleus and nucleus-nucleus interactions results in values of
+Power-of-Scale-freeness-of-Visibility-Graph-(PSVG) parameter extracted from the
+visibility graphs. Here, the relativistic nucleus-nucleus interaction data have
+been analysed to detect azimuthal-anisotropy by extending the Visibility Graph
+method and extracting the average clustering coefficient, one of the important
+topological parameters, from the graph. Azimuthal-distributions corresponding
+to different pseudorapidity-regions around the central-pseudorapidity value are
+analysed utilising the parameter. Here we attempt to correlate the conventional
+physical significance of this coefficient with respect to complex-network
+systems, with some basic notions of particle production phenomenology, like
+clustering and correlation. Earlier methods for detecting anisotropy in
+azimuthal distribution, were mostly based on the analysis of statistical
+fluctuation. In this work, we have attempted to find deterministic information
+on the anisotropy in azimuthal distribution by means of precise determination
+of topological parameter from a complex network perspective.",1710.10007v2
+2017-10-27,Anisotropy and multiband superconductivity in Sr2RuO4,"Despite numerous studies the exact nature of the order parameter in
+superconducting Sr2RuO4 remains unresolved. We have extended previous
+small-angle neutron scattering studies of the vortex lattice in this material
+to a wider field range, higher temperatures, and with the field applied close
+to both the <100> and <110> basal plane directions. Measurements at high field
+were made possible by the use of both spin polarization and analysis to improve
+the signal-to-noise ratio. Rotating the field towards the basal plane causes a
+distortion of the square vortex lattice observed for H // <001>, and also a
+symmetry change to a distorted triangular symmetry for fields close to <100>.
+The vortex lattice distortion allows us to determine the intrinsic
+superconducting anisotropy between the c-axis and the Ru-O basal plane,
+yielding a value of ~60 at low temperature and low to intermediate fields. This
+greatly exceeds the upper critical field anisotropy of ~20 at low temperature,
+reminiscent of Pauli limiting. Indirect evidence for Pauli paramagnetic effects
+on the unpaired quasiparticles in the vortex cores are observed, but a direct
+detection lies below the measurement sensitivity. The superconducting
+anisotropy is found to be independent of temperature but increases for fields >
+1 T, indicating multiband superconductvity in Sr2RuO4. Finally, the temperature
+dependence of the scattered intensity provides further support for gap nodes or
+deep minima in the superconducting gap.",1710.10310v1
+2017-11-02,Nearly isotropic superconductivity in layered Weyl semimetal WTe$_2$ at 98.5 kbar,"Layered transition metal dichalcogenide WTe$_2$ has recently attracted
+significant attention due to the discovery of an extremely large
+magnetoresistance, a predicted type-II Weyl semimetallic state, and the
+pressure-induced superconducting state. By a careful measurement of the
+superconducting upper critical fields as a function of the magnetic field angle
+at a pressure as high as 98.5 kbar, we provide the first detailed examination
+of the dimensionality of the superconducting condensate in WTe$_2$. Despite the
+layered crystal structure, the upper critical field exhibits a negligible field
+anisotropy. The angular dependence of the upper critical field can be
+satisfactorily described by the anisotropic mass model from 2.2 K
+($T/T_c\sim0.67$) to 0.03 K ($T/T_c\sim0.01$), with a practically identical
+anisotropy factor $\gamma\sim1.7$. The temperature dependence of the upper
+critical field, determined for both $H\perp ab$ and $H\parallel ab$, can be
+understood by a conventional orbital depairing mechanism. Comparison of the
+upper critical fields along the two orthogonal field directions results in the
+same value of $\gamma\sim1.7$, leading to a temperature independent anisotropy
+factor from near $T_c$ to $<0.01T_c$. Our findings thus identify WTe$_2$ as a
+nearly isotropic superconductor, with an anisotropy factor among one of the
+lowest known in superconducting transition metal dichalcogenides.",1711.00666v1
+2017-11-08,Coexistence of Magneto-Rotational and Jeans Instabilities in an Axisymmetric Nebula,"We analyze the magneto-rotational instability (MRI) effects on gravitational
+collapse and its influence on the instability critical scale. In particular, we
+study an axisymmetric nonstratified differentially rotating cloud, embedded in
+a small magnetic field, and we perform a local linear stability analysis,
+including the self gravity of the system. We demonstrate that the linear
+evolution of the perturbations is characterized by the emergence of an
+anisotropy degree of the perturbed mass densities. Starting with spherical
+growing overdensities, we see that they naturally acquire an anisotropy of
+order unity in their shape. Despite the linear character of our analysis, we
+infer that such a seed of anisotropy can rapidly grow in a nonlinear regime,
+leading to the formation of filament-like structures. However, we show how such
+an anisotropy is essentially an intrinsic feature of the Jean instability, and
+how MRI only plays a significant role in fixing the critical scale of the mode
+spectrum. We then provide a characterization of the present analysis in terms
+of the cosmological setting, in order to provide an outlook of how the present
+results could concern the formation of large-scale structures across the
+Universe.",1711.03010v4
+2017-11-08,Jets and large-scale vortices in rotating Rayleigh-Bénard convection,"One of the most prominent dynamical features of turbulent, rapidly-rotating
+convection is the formation of large-scale coherent structures, driven by
+Reynolds stresses resulting from the small-scale convective flows. In spherical
+geometry, such structures consist of intense zonal flows that are invariant
+along the rotation axis. In planar geometry, long-lived, depth-invariant
+structures also form at large scales, but, in the absence of horizontal
+anisotropy, they consist of vortices that grow to the domain size. In this
+work, through the introduction of horizontal anisotropy into a numerical model
+of planar rotating convection by the adoption of unequal horizontal box sizes
+(i.e. $L_x \le L_y$, where the $xy$-plane is horizontal), we investigate
+whether unidirectional flows and large-scale vortices can coexist. We find that
+only a small degree of anisotropy is required to bring about a transition from
+dynamics dominated by persistent large-scale vortices to dynamics dominated by
+persistent unidirectional flows parallel to the shortest horizontal direction.
+When the anisotropy is sufficiently large, the unidirectional flow consists of
+multiple jets, generated on a timescale smaller than a global viscous
+timescale, thus signifying that the upscale energy transfer does not
+spontaneously feed the largest available mode in the system. That said, the
+multiple jets merge on much longer timescales. Large-scale vortices of size
+comparable with $L_x$ systematically form in the flanks of the jets and can be
+persistent or intermittent. This indicates that large-scale vortices, either
+coexisting with jets or not, are a robust dynamical feature of planar rotating
+convection.",1711.03030v1
+2018-01-03,Investigation of the spin-1 honeycomb antiferromagnet BaNi$_2$V$_2$O$_8$ with easy plane anisotropy,"The magnetic properties of the two-dimensional, S=1 honeycomb antiferromagnet
+BaNi$_2$V$_2$O$_8$ have been comprehensively studied using DC susceptibility
+measurements and inelastic neutron scattering techniques. The magnetic
+excitation spectrum is found to be dispersionless within experimental
+resolution between the honeycomb layers, while it disperses strongly within the
+honeycomb plane where it consists of two gapped spin-wave modes. The magnetic
+excitations are compared to linear spin-wave theory allowing the Hamiltonian to
+be determined. The first- and second-neighbour magnetic exchange interactions
+are antiferromagnetic and lie within the ranges 10.90meV$\le$J$_n$$\le$13.35
+meV and 0.85meV$\le$J$_{nn}$$\le$1.65 meV respectively. The interplane coupling
+J$_{out}$ is four orders of magnitude weaker than the intraplane interactions,
+confirming the highly two-dimensional magnetic behaviour of this compound. The
+sizes of the energy gaps are used to extract the magnetic anisotropies and
+reveal substantial easy-plane anisotropy and a very weak in-plane easy-axis
+anisotropy. Together these results reveal that BaNi$_2$V$_2$O$_8$ is a
+candidate compound for the investigation of vortex excitations and
+Berezinsky-Kosterliz-Thouless phenomenona.",1801.00962v1
+2017-12-26,An accurate centroid algorithm for PSF reconstruction,"In this work, we present a novel centroiding method based on Fourier space
+Phase Fitting(FPF) for Point Spread Function(PSF) reconstruction. We generate
+two sets of simulations to test our method. The first set is generated by
+GalSim with elliptical Moffat profile and strong anisotropy which shifts the
+center of the PSF. The second set of simulation is drawn from CFHT i band
+stellar imaging data. We find non-negligible anisotropy from CFHT stellar
+images, which leads to $\sim$0.08 scatter in unit of pixels using polynomial
+fitting method Vakili and Hogg (2016). And we apply FPF method to estimate the
+centroid in real space, this scatter reduces to $\sim$0.04 in SNR=200 CFHT like
+sample. In low SNR (50 and 100) CFHT like samples, the background noise
+dominates the shifting of the centroid, therefore the scatter estimated from
+different methods are similar. We compare polynomial fitting and FPF using
+GalSim simulation with optical anisotropy. We find that in all SNR$\sim$50, 100
+and 200) samples, FPF performs better than polynomial fitting by a factor of
+$\sim$3. In general, we suggest that in real observations there are anisotropy
+which shift the centroid, and FPF method is a better way to accurately locate
+it.",1801.01015v1
+2018-01-08,Strong- and weak-universal critical behaviour of a mixed-spin Ising model with triplet interactions on the Union Jack (centered square) lattice,"The mixed spin-1/2 and spin-S Ising model on the Union Jack (centered square)
+lattice with four different three-spin (triplet) interactions and the uniaxial
+single-ion anisotropy is exactly solved by establishing a rigorous mapping
+equivalence with the corresponding zero-field (symmetric) eight-vertex model on
+a dual square lattice. A rigorous proof of the aforementioned exact mapping
+equivalence is provided by two independent approaches exploiting either a
+graph-theoretical or spin representation of the zero-field eight-vertex model.
+An influence of the interaction anisotropy as well as the uniaxial single-ion
+anisotropy on phase transitions and critical phenomena is examined in
+particular. It is shown that the considered model exhibits a strong-universal
+critical behaviour with constant critical exponents when considering the
+isotropic model with four equal triplet interactions or the anisotropic model
+with one triplet interaction differing from the other three. The anisotropic
+models with two different triplet interactions, which are pairwise equal to
+each other, contrarily exhibit a weak-universal critical behaviour with
+critical exponents continuously varying with a relative strength of the triplet
+interactions as well as the uniaxial single-ion anisotropy. It is evidenced
+that the variations of critical exponents of the mixed-spin Ising models with
+the integer-valued spins S differ basically from their counterparts with the
+half-odd-integer spins S.",1801.02676v1
+2018-01-19,Detecting Anisotropy in Fingerprint Growth,"From infancy to adulthood, human growth is anisotropic, much more along the
+proximal-distal axis (height) than along the medial-lateral axis (width),
+particularly at extremities. Detecting and modeling the rate of anisotropy in
+fingerprint growth, and possibly other growth patterns as well, facilitates the
+use of children's fingerprints for long-term biometric identification. Using
+standard fingerprint scanners, anisotropic growth is highly overshadowed by the
+varying distortions created by each imprint, and it seems that this difficulty
+has hampered to date the development of suitable methods, detecting anisotropy,
+let alone, designing models. We provide a tool chain to statistically detect,
+with a given confidence, anisotropic growth in fingerprints and its preferred
+axis, where we only require a standard fingerprint scanner and a minutiae
+matcher. We build on a perturbation model, a new Procrustes-type algorithm, use
+and develop several parametric and non-parametric tests for different
+hypotheses, in particular for neighborhood hypotheses to detect the axis of
+anisotropy, where the latter tests are tunable to measurement accuracy. Taking
+into account realistic distortions caused by pressing fingers on scanners, our
+simulations based on real data indicate that, for example, already in rather
+small samples (56 matches) we can significantly detect proximal-distal growth
+if it exceeds medial-lateral growth by only around 5 percent. Our method is
+well applicable to future datasets of children fingerprint time series and we
+provide an implementation of our algorithms and tests with matched minutiae
+pattern data.",1801.06437v1
+2018-01-21,Ce$_{3-x}$Mg$_x$Co$_{9}$: transformation of a Pauli paramagnet into a strong permanent magnet,"We report on the synthesis of single crystalline and polycrystalline samples
+of Ce$_{3-x}$Mg$_x$Co$_9$ solid solution ($0\leq x \lesssim 1.4$) and
+characterization of their structural and magnetic properties. The crystal
+structure remains rhombohedral in the whole composition range and Mg partially
+replaces Ce in the 6\textit{c} site of the CeCo$_3$ structure. Ferromagnetism
+is induced by Mg substitutions starting as low as $x=0.18$ and reaching a Curie
+temperature as high as $450$\,K for $x=1.35$. Measurements on single crystals
+with $x=1.34$ and $T_\textrm{C}=440$\,K indicate an axial magnetic anisotropy
+with the anisotropy field of $6$\,T and a magnetization of $6$\,$\mu_B/$f.u. at
+$300$\,K. Coercicity is observed in the polycrystalline samples consistent with
+the observed axial magnetic anisotropy. Our discovery of ferromagnetism with
+large axial magnetic anisotropy induced by substituting a rare-earth element by
+Mg is a very promising result in the search of inexpensive permanent-magnet
+materials and suggests other non-magnetic phases, similar to CeCo$_3$, may also
+conceal nearby ferromagnetic phases.",1801.06743v2
+2018-01-31,"Cubic anisotropy in high homogeneity thin (Ga,Mn)As layers","Historically, comprehensive studies of dilute ferromagnetic semiconductors,
+e.g., $p$-type (Cd,Mn)Te and (Ga,Mn)As, paved the way for a quantitative
+theoretical description of effects associated with spin-orbit interactions in
+solids, such as crystalline magnetic anisotropy. In particular, the theory was
+successful in explaining {\em uniaxial} magnetic anisotropies associated with
+biaxial strain and non-random formation of magnetic dimers in epitaxial
+(Ga,Mn)As layers. However, the situation appears much less settled in the case
+of the {\em cubic} term: the theory predicts switchings of the easy axis
+between in-plane $\langle 100\rangle$ and $\langle 110\rangle$ directions as a
+function of the hole concentration, whereas only the $\langle 100\rangle$
+orientation has been found experimentally. Here, we report on the observation
+of such switchings by magnetization and ferromagnetic resonance studies on a
+series of high-crystalline quality (Ga,Mn)As films. We describe our findings by
+the mean-field $p$-$d$ Zener model augmented with three new ingredients. The
+first one is a scattering broadening of the hole density of states, which
+reduces significantly the amplitude of the alternating carrier-induced
+contribution. This opens the way for the two other ingredients, namely the
+so-far disregarded single-ion magnetic anisotropy and disorder-driven
+non-uniformities of the carrier density, both favoring the $\langle 100\rangle$
+direction of the apparent easy axis. However, according to our results, when
+the disorder gets reduced a switching to the $\langle 110\rangle$ orientation
+is possible in a certain temperature and hole concentration range.",1802.00076v2
+2018-02-22,Magnetic properties of metal-organic coordination networks based on 3d transition metal atoms,"The magnetic anisotropy and exchange coupling between spins localized at the
+positions of 3d transition metal atoms forming two-dimensional metal-organic
+coordination networks (MOCNs) grown on the Au(111) metal surface are studied.
+In particular, we consider MOCNs made of Ni or Mn metal centers linked by TCNQ
+(7,7,8,8-tetracyanoquinodimethane) organic ligands, which form rectangular
+networks with 1:1 stoichiometry. Based on the analysis of X-ray magnetic
+circular dichroism (XMCD) data taken at T= 2.5 K, we find that Ni atoms in the
+Ni-TCNQ MOCNs are coupled ferromagnetically and do not show any significant
+magnetic anisotropy, while Mn atoms in the Mn-TCNQ MOCNs are coupled
+antiferromagnetically and do show a weak magnetic anisotropy with
+in-planemagnetization. We explain these observations using both
+amodelHamiltonian based on mean-fieldWeiss theory and density functional theory
+calculations that include spin-orbit coupling. Our main conclusion is that the
+antiferromagnetic coupling between Mn spins and the in-plane magnetization of
+the Mn spins can be explained neglecting effects due to the presence of the
+Au(111) surface, while for Ni-TCNQ the metal surface plays a role in
+determining the absence of magnetic anisotropy in the system.",1802.08243v1
+2018-03-20,Anisotropy in electrical conductivity and transparency of films of aligned conducting rods,"Numerical simulations by means of the Monte Carlo method have been performed
+to study the electrical properties of a two-dimensional composite filled with
+rodlike particles. The main goal was to study the effect of the alignment of
+such rods on the anisotropy of its electrical conductivity. A continuous model
+was used. In this model, the rods have zero-width (i.e. infinite aspect ratio)
+and they may intersect each other. To involve both the low conductive host
+matrix, and highly conductive fillers (rods) in the consideration, a
+discretization algorithm based on the use of a supporting mesh was applied. The
+discretization is equivalent to the substitution of rods with the polyominoes.
+Once discretized, the Frank--Lobb algorithm was applied to evaluate the
+electrical conductivity. Our main findings are (i) the alignment of the rods
+essentially affects the electrical conductivity and its anisotropy, (ii)the
+discrete nature of computer simulations is crucial. For slightly disordered
+system, high electrical anisotropy was observed at small filler content,
+suggesting a method to enable the production of optically transparent and
+highly anisotropic conducting films.",1803.07354v1
+2018-03-26,Enhancement of the magnetoelectric effect in multiferroic CoFe$_2$O$_4$/PZT bilayer by induced uniaxial magnetic anisotropy,"In this study we have compared magnetic, magnetostrictive and piezomagnetic
+properties of isotropic and anisotropic cobalt ferrite pellets. The isotropic
+sample was prepared by the ceramic method while the sample exhibiting uniaxial
+anisotropy was made by reactive sintering using Spark Plasma Sintering (SPS).
+This technique permits to induce a magnetic anisotropy in cobalt ferrite in the
+direction of the applied pressure during SPS process. Sample with uniaxial
+anisotropy revealed a higher longitudinal magnetostriction and piezomagnetism
+compared to the isotropic sample, but the transversal magnetostriction and
+piezomagnetism were dramatically reduced. In the case of magnetoelectric
+layered composite, the magnetoelectric coefficient is directly related to the
+sum of the longitudinal and transversal piezomagnetic coefficients. These two
+coefficients being opposite in sign, the use of material exhibiting high
+longitudinal and low transversal piezomagnetic coefficient (or vice versa) in
+ME devices is expected to improve the ME effect. Hence, ME bilayer devices were
+made using isotropic and anisotropic cobalt ferrite stuck with a PZT layer. ME
+measurements at low frequencies revealed that bilayer with anisotropic cobalt
+ferrite exhibits a ME coefficient three times higher than a bilayer with
+isotropic cobalt ferrite. We also investigated the behavior of such composites
+when excited at resonant frequency.",1803.09677v1
+2018-04-08,Statistical tracing of magnetic fields: comparing and improving the techniques,"Magnetohydrodynamic(MHD) turbulence displays velocity anisotropies which
+reflect the direction of the magnetic field. This anisotropy has led to the
+development of a number of statistical techniques for studying magnetic fields
+in the interstellar medium. In this paper, we review and compare three
+techniques that use radio position-position-velocity data for determining
+magnetic field strength and morphology : the correlation function anisotropy
+(CFA), Principal Component Analysis of Anisotropies (PCAA), and the more recent
+Velocity Gradient Technique (VGT). We compare these three techniques and
+suggest improvements to the CFA and PCAA techniques to increase their accuracy
+and versatility. In particular, we suggest and successfully implement a much
+faster way of calculating non-periodic correlation functions for the CFA. We
+discuss possible improvements to the current implementation of the PCAA. We
+show the advantages of the VGT in terms of magnetic field tracing and stress
+the complementary nature with the other two techniques.",1804.02732v2
+2018-04-13,Enhanced mobility of discrete solitons in anisotropic two-dimensional waveguide arrays with modulated separations,"We consider two-dimensional waveguide arrays with anisotropic coupling
+coefficients. We show using numerical and variational calculations that four
+stationary soliton types exist: Site-Centered, Bond-Centered, Hybrid-X and
+Hybrid-Y. For the isotropic case the last two modes become identical and
+equivalent to the known hybrid soliton. With a variational calculation using a
+gaussian trial function and six variational parameters corresponding to the
+soliton's position, width, and velocity components, the four stationary soliton
+types are reproduced and their equilibrium widths are accounted for accurately
+for a wide range of anisotropy ratios. We obtained using the variational
+calculation the Peierls-Nabarro potential and barrier heights for the four
+soliton types and different anisotropy ratios. We have also obtained a phase
+diagram showing regions of soliton stability against collapse and subregions of
+mobility in terms of the initial kick-in speed and anisotropy ratio. The phase
+diagram shows that 2D solitons become highly mobile for anisotropy ratios
+larger than some critical values that depend on the initial kick-in speed. This
+fact was then exploited to design tracks within the 2D waveguide array along
+which the soliton can be accelerated and routed. We have calculated the actual
+waveguide separations needed to realist the proposed guided trajectories of 2D
+solitons.",1804.04896v1
+2018-04-21,"Dipole Anisotropy as an Essential Qualifier for the Monopole Component of the Cosmic-Dawn Spectral Signature, and the Potential of Diurnal Pattern for Foreground Estimation","While the importance of detecting the Global spectral signatures of the
+red-shifted 21-cm line of atomic hydrogen from the very early epochs cannot be
+overstated, the associated challenges primarily include isolating the weak
+signal of interest from the orders of magnitude brighter foregrounds, and
+extend equally to reliably establishing the origin of the {\it apparent} global
+signal to the very early epochs. This letter proposes a critical dipole test
+that the measurements of the monopole component of the spectrum of interest
+should necessarily pass. Our criterion is based on a unique correspondence
+between the intrinsic monopole spectrum and the differential spectrum as an
+imprint of dipole anisotropy resulting from motion of observer with respect to
+the rest frame of our source (such as that of our Solar system, interpreted
+from the dipole anisotropy in CMBR). More importantly, the spectral
+manifestation of the dipole anisotropy gets {\it amplified} by a significant
+factor, depending on the monopole spectral slopes, rendering it feasible to
+measure. We describe details of such a test, and illustrate its application
+with the help of simulations. The letter also alludes to a novel
+model-independent path toward isolating the foreground contribution, using the
+diurnal pattern readily apparent in drift-scan observations. Such dipole
+qualifier for the monopole spectrum, when combined with reliable foreground
+estimation, is expected to pave way for in situ validation of spectral
+signatures from early epochs, important to presently reported and future
+detections of EoR signal.",1804.07993v3
+2018-04-23,"Dependence of light scattering properties on porosity, size and composition of dust aggregates","In this work, we study the light scattering properties of dust aggregates
+($0.7\mu m \lesssim R_c \lesssim 2.0\mu m$) having a wide range of porosity
+($\mathcal{P}$ = 0.59 to 0.98). The simulations are executed using the
+Superposition T-matrix code with BCCA, BA, BAM1 and BAM2 clusters of varying
+porosity. We investigate the nature and dependencies of the different
+scattering parameters on porosity, size and composition of the aggregated
+particles for wavelengths 0.45 $\mu$m and 0.65 $\mu$m. We find that the
+scattering parameters are strongly correlated with the porosity of the
+aggregated structures. Our results indicate that, when the porosity of the
+aggregates decreases, keeping characteristic radius of the aggregates ($R_c$)
+same for all structures, there is an enhancement in the negative polarization
+branch (NPB) which is accompanied by a substantial increase in the anisotropies
+present in the material. Also at the exact backscattering region, the
+anisotropies are found to be linearly correlated with the porosity of the
+aggregated structure. The computational study reveals that, for low absorbing
+materials ($k \le 0.1$), the negative polarization minimum ($P_{min}$) is
+strongly correlated with the associated anisotropies. Finally, we put forward a
+qualitative comparison between our computationally obtained results and some
+selected data from the Amsterdam Light Scattering Database for both low and
+high absorbing materials. The experimental results also suggest that an
+increase in the NPB is always accompanied by an enhancement in the anisotropy
+at the backscattering region.",1804.08324v1
+2018-06-06,The effect of stellar-mass black holes on the central kinematics of omega Cen: a cautionary tale for IMBH interpretations,"The search for intermediate-mass black holes (IMBHs) in the centre of
+globular clusters is often based on the observation of a central cusp in the
+surface brightness profile and a rise towards the centre in the velocity
+dispersion profiles. Similar signatures, however, could result from other
+effects, that need to be taken into account in order to determine the presence
+(or the absence) of an IMBH in these stellar systems. Following our previous
+exploration of the role of radial anisotropy in shaping these observational
+signatures, we analyse here the effects produced by the presence of a
+population of centrally concentrated stellar-mass black holes. We fit dynamical
+models to omega Cen data, and we show that models with ~5% of their mass in
+black holes (consistent with ~100% retention fraction after natal kicks) can
+reproduce the data. When simultaneously considering both radial anisotropy and
+mass segregation, the best-fit model includes a smaller population of remnants,
+and a less extreme degree of anisotropy with respect to the models that include
+only one of these features. These results underline that before conclusions
+about putative IMBHs can be made, the effects of stellar-mass black holes and
+radial anisotropy need to be properly accounted for.",1806.02157v1
+2018-06-23,MMS Observations of Beta-Dependent Constraints on Ion Temperature-Anisotropy in Earth's Magnetosheath,"Protons (ionized hydrogen) in the solar wind frequently exhibit distinct
+temperatures ($T_{\perp p}$ and $T_{\parallel p}$) perpendicular and parallel
+to the plasma's background magnetic-field. Numerous prior studies of the
+interplanetary solar-wind have shown that, as plasma beta ($\beta_{\parallel
+p}$) increases, a narrower range of temperature-anisotropy ($R_p\equiv T_{\perp
+p}\,/\,T_{\parallel p}$) values is observed. Conventionally, this effect has
+been ascribed to the actions of kinetic microinstabilities. This study is the
+first to use data from the Magnetospheric Multiscale Mission (MMS) to explore
+such $\beta_{\parallel p}$-dependent limits on $R_p$ in Earth's magnetosheath.
+The distribution of these data across the $(\beta_{\parallel p},R_p)$-plane
+reveals limits on both $R_p>1$ and $R_p<1$. Linear Vlasov theory is used to
+compute contours of constant growth-rate for the ion-cyclotron, mirror,
+parallel-firehose, and oblique-firehose instabilities. These instability
+thresholds closely align with the contours of the data distribution, which
+suggests a strong association of instabilities with extremes of ion temperature
+anisotropy in the magnetosheath. The potential for instabilities to regulate
+temperature anisotropy is discussed.",1806.08886v1
+2018-07-19,Small system studies: A theory overview,"There is now a substantial body of evidence that a deconfined quark-gluon
+plasma is created in ultrarelativistic collisions of heavy nuclei. Some key
+observables which are used to gauge the production of the quark-gluon plasma
+are the hadronic spectra and multiplicities across many species, azimuthal
+anisotropies in the production of various hadrons, jet quenching,
+photon/dilepton production, and heavy quarkonium suppression. A key question in
+the study of the quark-gluon plasma is what happens to these observables as one
+changes the system size. In particular, it is very interesting to study
+collisions of `small systems' such as pp, dA, pA, and $e^+ e^-$ since naively
+one does not expect to produce a QGP in these cases. One of the surprises from
+such studies was the existence of sizable azimuthal anisotropies in the hadron
+spectra in the highest multiplicity classes, which led to speculations that one
+can generate a QGP in such relatively rare events. This interpretation,
+however, is complicated by the fact that there can be multiple sources of
+azimuthal anisotropy. I will discuss our current understanding of the different
+sources of azimuthal anisotropies and the multiplicity windows in which each
+mechanism is expected to dominate. I will also provide a critical discussion of
+the reliability of hydrodynamic models applied to small systems. Finally, I
+will briefly discuss jet quenching and heavy quarkonium suppression in small
+systems and discuss whether or not these observables show any indication of the
+production of a small QGP droplet.",1807.07191v2
+2018-08-16,Estimating the Anisotropy of Protein Structures from SAXS,"In the field of small angle x-ray scattering (SAXS), the task of estimating
+the size of particles in solution is usually synonymous with the Guinier plot.
+The approximation behind this plot, developed by Guinier in 1939 provides a
+simple yet accurate characterization of the scattering behavior of particles at
+low scattering angle $q$, together with a computationally efficient way of
+inferring their radii of gyration $R_G$. Moreover, this approximation is valid
+beyond spherical scatterers, making its use ubiquitous in the SAXS world.
+However, when it is important to estimate further particle characteristics,
+such as the anisotropy of the scatterer's shape, no similar or extended
+approximations are available. Existing tools to characterize the shape of
+scatterers rely either on prior knowledge of the scatterers' geometry or on
+iterative procedures to infer the particle shape \textit{ab initio}.\\
+  In this work we develop a low angle approximation of the scattering intensity
+$I(q)$ for ellipsoids of revolution and show how to extract size and anisotropy
+information from the parameters of that approximation. Beyond ideal ellipsoids
+of revolution, we show that this approximation can be used to infer the size
+and shape of molecules in solution, both in computational and experimental
+scenarios. We discuss the limits of our approach and study the impact of a
+particle's anisotropy in the Guinier estimate of $R_G$.",1808.05569v1
+2018-09-20,Universal Fermi-surface anisotropy renormalization for interacting Dirac fermions with long-range interactions,"Recent experimental and numerical evidence suggest an intriguing universal
+relationship between the Fermi surface anisotropy of the non-interacting parent
+two-dimensional electron gas and the strongly correlated composite Fermi liquid
+formed in a strong magnetic field close to half-filing. Inspired by these
+observations, we explore more generally the question of anisotropy
+renormalization in interacting 2D Fermi systems. Using a recently developed
+non-perturbative and numerically-exact projective quantum Monte Carlo
+simulation as well as other numerical and analytic techniques, only for Dirac
+fermions with long-range Coulomb interactions do we find a universal
+square-root decrease of the Fermi-surface anisotropy. For the half-filled
+composite Fermi liquid, this result is surprising since a Dirac fermion ground
+state was only recently proposed as an alternative to the usual HLR state. The
+importance of the long-range interaction, expected for Dirac systems, is also
+consistent with recent transport measurements. Our proposed universality can be
+tested in several anisotropic Dirac materials including graphene, topological
+insulators organic conductors, and magic-angle twisted bilayer graphene.",1809.07775v2
+2018-10-04,Prospects of detecting a large-scale anisotropy of ultra-high-energy cosmic rays from a nearby source with the K-EUSO orbital telescope,"KLYPVE-EUSO (K-EUSO) is a planned orbital detector of ultra-high-energy
+cosmic rays (UHECRs), which is to be deployed on board the International Space
+Station. K-EUSO is expected to have a uniform exposure over the celestial
+sphere and register from 120 to 500 UHECRs at energies above 57 EeV in a 2-year
+mission. We employed the TransportCR and CRPropa 3 packages to estimate
+prospects of detecting a large-scale anisotropy of ultra-high-energy cosmic
+rays from a nearby source with K-EUSO. Nearby active galactic nuclei Centaurus
+A, M82, NGC 253, M87 and Fornax A were considered as possible sources of
+UHECRs. A minimal model for extragalactic cosmic rays and neutrinos by
+Kachelriess, Kalashev, Ostapchenko and Semikoz (2017) was chosen for
+definiteness. We demonstrate that an observation of $\gtrsim300$ events will
+allow detecting a large-scale anisotropy with a high confidence level providing
+the fraction of from-source events is $\simeq$10-15%, depending on a particular
+source. The threshold fraction decreases with an increasing sample size. We
+also discuss if an overdensity originating from a nearby source can be observed
+at around the ankle in case a similar anisotropy is found beyond 57 EeV. The
+results are generic and hold for other future experiments with a uniform
+exposure of the celestial sphere.",1810.02284v3
+2018-10-16,Density jump as a function of magnetic field strength for parallel collisionless shocks in pair plasmas,"Collisionless shocks follow the Rankine-Hugoniot jump conditions to a good
+approximation. However, for a shock propagating parallel to a magnetic field,
+magnetohydrodynamics states that the shock properties are independent of the
+field strength, whereas recent Particle-in-Cell simulations reveal a
+significant departure from magnetohydrodynamics behavior for such shocks in the
+collisionless regime. This departure is found to be caused by a field-driven
+anisotropy in the downstream pressure, but the functional dependence of this
+anisotropy on the field strength is yet to be determined. Here, we present a
+non-relativistic model of the plasma evolution through the shock front,
+allowing for a derivation of the downstream anisotropy in terms of the field
+strength. Our scenario assumes double adiabatic evolution of a pair plasma
+through the shock front. As a result, the perpendicular temperature is
+conserved. If the resulting downstream is firehose stable, then the plasma
+remains in this state. If unstable, it migrates towards the firehose stability
+threshold. In both cases, the conservation equations, together with the
+relevant hypothesis made on the temperature, allows a full determination of the
+downstream anisotropy in terms of the field strength.",1810.07319v1
+2018-10-20,Data-Driven Modelling of the Reynolds Stress Tensor using Random Forests with Invariance,"A novel machine learning algorithm is presented, serving as a data-driven
+turbulence modeling tool for Reynolds Averaged Navier-Stokes (RANS)
+simulations. This machine learning algorithm, called the Tensor Basis Random
+Forest (TBRF), is used to predict the Reynolds-stress anisotropy tensor, while
+guaranteeing Galilean invariance by making use of a tensor basis. By modifying
+a random forest algorithm to accept such a tensor basis, a robust, easy to
+implement, and easy to train algorithm is created. The algorithm is trained on
+several flow cases using DNS/LES data, and used to predict the Reynolds stress
+anisotropy tensor for new, unseen flows. The resulting predictions of
+turbulence anisotropy are used as a turbulence model within a custom RANS
+solver. Stabilization of this solver is necessary, and is achieved by a
+continuation method and a modified $k$-equation. Results are compared to the
+neural network approach of Ling et al. [J. Fluid Mech, 807(2016):155-166,
+(2016)]. Results show that the TBRF algorithm is able to accurately predict the
+anisotropy tensor for various flow cases, with realizable predictions close to
+the DNS/LES reference data. Corresponding mean flows for a square duct flow
+case and a backward facing step flow case show good agreement with DNS and
+experimental data-sets. Overall, these results are seen as a next step towards
+improved data-driven modelling of turbulence. This creates an opportunity to
+generate custom turbulence closures for specific classes of flows, limited only
+by the availability of LES/DNS data.",1810.08794v2
+2019-01-05,Evolution of magnetic anisotropy in cobalt film on nanopatterned silicon substrate studied in situ using MOKE,"Evolution of magnetization behaviour of cobalt film on nano patterned silicon
+substrate, with film thickness, has been studied. In situ magneto-optical Kerr
+effect measurements during film deposition allowed us to study genuine
+thickness dependence of magnetization behaviour, all other parameters like
+surface topology, deposition conditions remaining invariant. The film exhibits
+uniaxial magnetic anisotropy, with its magnitude decreasing with increasing
+film thickness. Analysis shows that anisotropy has contributions from both, i)
+exchange energy which is volume dependent and, ii) stray dipolar fields at the
+surface/interface. This suggests that local magnetization follows only
+partially the topology of the rippled surface. As expected from energy
+considerations, for small film thickness, the local magnetization closely
+follows the surface contour of the ripples making the volume term as the
+dominant contribution. With increasing film thickness, the local magnetization
+gradually deviates from the local slope and approaches towards a uniform
+magnetization along the macroscopic film plane making the surface term as the
+dominant contribution. Significant deviation from the anisotropy energy
+expected on the basis of theoretical considerations can be attributed to
+several factors like, deviation of surface topology from an ideal sinusoidal
+wave, breaks of continuity along the ripple direction, defects like pattern
+dislocations, and possible decrease in surface modulation depth with increasing
+film thickness.",1901.01397v1
+2019-03-27,High throughput computational screening for 2D ferromagnetic materials: the critical role of anisotropy and local correlations,"The recent observation of ferromagnetic order in two-dimensional (2D)
+materials has initiated a booming interest in the subject of 2D magnetism. In
+contrast to bulk materials, 2D materials can only exhibit magnetic order in the
+presence of magnetic anisotropy. In the present work we have used the
+Computational 2D Materials Database (C2DB) to search for new ferromagnetic 2D
+materials using the spinwave gap as a simple descriptor that accounts for the
+role of magnetic anisotropy. In addition to known compounds we find 12 novel
+insulating materials that exhibit magnetic order at finite temperatures. For
+these we evaluate the critical temperatures from classical Monte Carlo
+simulations of a Heisenberg model with exchange and anisotropy parameters
+obtained from first principles. Starting from 150 stable ferromagnetic 2D
+materials we find five candidates that are predicted to have critical
+temperatures exceeding that of CrI3. We also study the effect of Hubbard
+corrections in the framework of DFT+U and find that the value of U can have a
+crucial influence on the prediction of magnetic properties. Our work provides
+new insight into 2D magnetism and identifies a new set of promising monolayers
+for experimental investigation.",1903.11466v2
+2019-04-07,Homogenization of Norton-Hoff fibered composites with high contrast,"We study the steady creep flow of a perfectly viscoplastic solid reinforced
+by fibers with high viscosity contrast. Our study unveils new effects related
+to anisotropy and conditioned by the Norton exponent.",1904.03622v2
+2019-04-19,Crystal plasticity analysis of deformation anisotropy of lamellar TiAl alloy: 3D microstructure-based modelling and in-situ micro-compression,"Detailed microstructure characterisation and in-situ micropillar compression
+were coupled with crystal plasticity-based finite element modelling (CP-FEM) to
+study the micro-mechanisms of plastic anisotropy in lamellar TiAl alloys. The
+consideration of microstructure in both simulation and in-situ experiments
+enables in-depth understanding of micro-mechanisms responsible for the highly
+anisotropic deformation response of TiAl on the intra-lamella and inter-lamella
+scales. This study focuses on two specific configurations of
+{\gamma}/{\alpha}_2 lamellar microstructure with the {\gamma}/{\alpha}_2
+interfaces being aligned {25}^o and {55}^o to the loading direction.
+Microstructure-based CP-FEM shows that longituginal slip of super and ordinary
+dislocations are most responsible for the plastic anisotropy in the {25}^o
+micropillar while the anisotropy of the {55}^o micropillar is due to
+longitudinal superdislocations and longitudinal twins. In addition, transversal
+superdislocations were more active, making the deformation in the {25}^o
+micropillar less localised than that in the {55}^o micropillar. Moreover, the
+CP-FEM model successfully predicted substantial build-up of internal stresses
+at {\gamma}/{\alpha}_2 interfaces, which is believed to be detrimental to the
+ductility in TiAl. However, as evidenced by the model, the detrimental internal
+stresses can be significantly relieved by the activation of transverse
+deformation twinning, suggesting that the ductility of TiAl can be improved by
+promoting transverse twins.",1904.09206v1
+2019-05-10,Elastic Anisotropy Governs the Decay of Cell-induced Displacements,"The unique nonlinear mechanics of the fibrous extracellular matrix (ECM)
+facilitates long-range cell-cell mechanical communications that would be
+impossible on linear elastic substrates. Past research has described the
+contribution of two separated effects on the range of force transmission,
+including ECM elastic non-linearity and fiber alignment. However, the relation
+between these different effects is unclear, and how they combine to dictate
+force transmission range is still elusive. Here, we combine discrete fiber
+simulations with continuum modeling to study the decay of displacements induced
+by a contractile cell in fibrous networks. We demonstrate that fiber
+non-linearity and fiber reorientation both contribute to the strain-induced
+anisotropy of the elastic moduli of the cell local environment. This elastic
+anisotropy is a parameter that governs the slow decay of the displacements, and
+it depends on the magnitude of applied strain, either an external tension or an
+internal contraction as a model of the cell. Furthermore, we show that
+accounting for artificially-prescribed elastic anisotropy dictates the
+displacement decay induced by a contracting cell. Our findings unify previous
+single effects into a mechanical theory that explains force transmission in
+fibrous networks. This work provides important insights into biological
+processes that involve the coordinated action of distant cells mediated by the
+ECM, such that occur in morphogenesis, wound healing, angiogenesis, and cancer
+metastasis. It may also provide design parameters for biomaterials to control
+force transmission between cells, as a way to guide morphogenesis in tissue
+engineering.",1905.04345v1
+2019-06-27,An anisotropic model for global climate data,"We present a new, elementary way to obtain axially symmetric Gaussian
+processes on the sphere, in order to accommodate for the directional anisotropy
+of global climate data in geostatistical analysis.",1906.11585v1
+2019-07-19,Impact of main ion pressure anisotropy on stellarator impurity transport,"Main ions influence impurity dynamics through a variety of mechanisms; in
+particular, via impurity-ion collisions. To lowest order in an expansion in the
+main ion mass over the impurity mass, the impurity-ion collision operator only
+depends on the component of the main ion distribution that is odd in the
+parallel velocity. These lowest order terms give the parallel friction of the
+impurities with the main ions, which is typically assumed to be the main cause
+of collisional impurity transport. Next-order terms in the mass ratio expansion
+of the impurity-ion collision operator, proportional to the component of the
+main ion distribution that is even in the parallel velocity, are usually
+neglected. However, in stellarators, the even component of the main ion
+distribution can be very large. In this article, such next-order terms in the
+mass ratio expansion of the impurity-ion collision operator are retained, and
+analytical expressions for the neoclassical radial flux of trace impurities are
+calculated in the Pfirsch-Schl\""uter, plateau and $1/\nu$ regimes. The new
+terms provide a drive for impurity transport that is physically very different
+from parallel friction: they are associated to anisotropy in the pressure of
+the main ions, which translates into impurity pressure anisotropy. It is argued
+that main ion pressure anisotropy must be taken into account for a correct
+description of impurity transport in certain realistic stellarator plasmas.
+Examples are given by numerically evaluating the analytical expressions for the
+impurity flux.",1907.08482v2
+2019-08-03,Nanoscale magnetic and charge anisotropies at manganite interfaces,"Strong correlated manganites are still under intense research owing to their
+complex phase diagrams in terms of the Sr-doping and their sensitivity to
+intrinsic and extrinsic structural deformations. Here, we performed x-ray
+absorption spectroscopy measurements of manganites bilayers to explore the
+effects that a local Sr-doping gradient produce on the charge and
+antiferromagnetic anisotropies. In order to gradually tune the Sr-doping level
+along the axis perpendicular to the samples we have grown a series of bilayers
+with different thicknesses of low-doped manganites (from 0 nm to 6 nm)
+deposited over a La0.7Sr0.3MnO3 metallic layer. This strategy permitted us to
+resolve with high accuracy the thickness region where the charge and spin
+anisotropies vary and the critical thickness tc over which the out of plane
+orbital asymmetry does not have any further modifications. We found that the
+antiferromagnetic spin axis points preferentially out of the sample plane
+regardless the capping layer thickness. However, it tilts partially into the
+sample plane far from this critical thickness, owing to the jointed
+contributions of the external structural strain and electron doping.
+Furthermore, we found that the doping level of the capping layer sensibly
+affects the critical thickness, giving clear evidence of the influence exerted
+by the electron doping on the orbital and magnetic configurations. These
+anisotropy changes induce subtle modifications on the domain reorientation of
+the La0.7Sr0.3MnO3, as evidenced from the magnetic hysteresis cycles.",1908.01196v1
+2019-09-20,A new class of galaxy models with a central BH -- I. The spherical case,"The dynamical properties of spherically symmetric galaxy models, where a
+Jaffe (1983) stellar density profile is embedded in a total mass density
+decreasing as $r^{-3}$ at large radii, are presented. The orbital structure of
+the stellar component is described by the Osipkov--Merritt anisotropy; the dark
+matter halo is isotropic, and a black hole is added at the center of the
+galaxy. First, the conditions for a nowhere negative and monotonically
+decreasing dark matter halo density profile are derived; this profile can be
+made asymptotically coincident with a NFW profile at the center and at large
+radii. Then the minimum value of the anisotropy radius for phase-space
+consistency is derived as a function of the galaxy parameters. The Jeans
+equations for the stellar component are solved analytically; the projected
+velocity dispersion at the center and at large radii is also obtained, for
+generic values of the anisotropy radius. Finally, analytical expressions for
+the terms entering the Virial Theorem are derived, and the fiducial anisotropy
+limit required to prevent the onset of Radial Orbit Instability is determined
+as a function of the galaxy parameters. The presented models, built following
+an approach already adopted in our previous works, can be a useful starting
+point for a more advanced modeling of the dynamics of elliptical galaxies, and
+can be easily implemented in numerical simulations requiring a realistic
+dynamical model of a galaxy.",1909.09639v1
+2019-09-26,Electrical manipulation of magnetic anisotropy in a Fe$_{81}$Ga$_{19}$/PMN-PZT magnetoelectric multiferroic composite,"Magnetoelectric composites are an important class of multiferroic materials
+that pave the way towards a new generation of multifunctional devices directly
+integrable in data storage technology and spintronics. This study focuses on
+strain-mediated electrical manipulation of magnetization in an extrinsic
+multiferroic. The composite includes 5 nm or 60 nm Fe$_{81}$Ga$_{19}$ thin
+films coupled to a piezoelectric (011)-PMN-PZT. The magnetization reversal
+study reveals a converse magnetoelectric coefficient $\alpha_\mathrm{CME,max}
+\approx 2.7 \times {10^{-6}}$ s.m$^{-1}$ at room temperature. This reported
+value of $\alpha_\mathrm{CME}$ is among the highest so far compared to previous
+reports of single-phase multiferroics as well as composites. An angular
+dependency of $\alpha_\mathrm{CME}$ is also shown for the first time, arising
+from the intrinsic magnetic anisotropy of FeGa. The highly efficient
+magnetoelectric composite FeGa/PMN-PZT demonstrates drastic modifications of
+the in-plane magnetic anisotropy, with an almost 90$^{\circ}$ rotation of the
+preferential anisotropy axis in the thinner films under an electric field E =
+10.8 kV.cm$^{-1}$. Also, the influence of thermal strain on the bilayer's
+magnetic coercivity is compared to that of a reference bilayer FeGa/Glass at
+cryogenic temperatures. A different evolution is observed as a function of
+temperature, revealing a substrate thermo-mechanical influence which has not
+yet been reported in FeGa thin films coupled to a piezoelectric material.",1909.12431v1
+2019-10-15,Superconducting Correlations in the One-Dimensional Kondo Lattice Models under Magnetic Fields,"We analyze superconducting correlations in the one-dimensional Kondo lattice
+models with Ising anisotropy under transverse magnetic fields, using the
+density matrix renormalization group. For the spin-1/2 local spin model, the
+Ising anisotropy is introduced by the ferromagnetic Ising interaction between
+the local spins, while for the spin-1 model, it is taken by the single-ion
+anisotropy. The magnetic properties under the transverse fields for the
+spin-1/2 model are very similar to those for the spin-1 model [K. Suzuki and K.
+Hattori, J. Phys. Soc. Jpn. 88, 024707 (2019).]. For the superconducting
+correlations, we analyze various Cooper pairs within nearest-neighbor pairs
+including composite ones between the local spins and the electrons. We find
+that, for the spin-1/2 model, the superconducting correlations are highly
+enhanced in the Tomonaga-Luttinger liquid state near the Kondo-plateau phase,
+where the conduction electrons and the local spins are strongly coupled with a
+finite spin gap for the Ising axis. This is a clear contrast to the model under
+the longitudinal magnetic fields, where there are no noticeable superconducting
+correlations. Competitions between the transverse magnetic field and the Kondo
+singlet formation lead to this enhanced superconducting correlations. For the
+spin-1 model, the single-ion anisotropy suppresses the superconducting
+correlation and there is no noticeable enhancement. We also examine the large
+Kondo exchange coupling limit. For the moderate ferromagnetic Ising interaction
+between the local spins, we find that another type of superconducting
+correlation is enhanced inside the ferromagnetic phase. We discuss a possible
+relation between our results and reentrant superconductivity in U-based
+ferromagnetic superconductors under transverse magnetic fields.",1910.06545v2
+2019-11-21,Heat capacity of anisotropic Heisenberg antiferromagnet within the spin Hartree-Fock approach in quasi-1D Regime,"We study the anisotropic quantum Heisenberg antiferromagnet for spin-1/2 that
+interpolates smoothly between the one-dimensional (1D) and the two-dimensional
+(2D) limits. Using the spin Hartree-Fock approach we construct a quantitative
+theory of heat capacity in the quasi-1D regime with a finite coupling between
+spin chains. This theory reproduces closely the exact result of Bethe Ansatz in
+the 1D limit and does not produces any spurious phase transitions for any
+anisotropy in the quasi-1D regime at finite temperatures in agreement with the
+Mermin-Wagner theorem. We study the static spin-spin correlation function in
+order to analyse the interplay of lattice geometry and anisotropy in these
+systems. We compare the square and triangular lattice. For the latter we find
+that there is a quantum transition point at an intermediate anisotropy of
+$\sim0.6$. This quantum phase transition establishes that the quasi-1D regime
+extends upto a particular point in this geometry. For the square lattice the
+change from the 1D to 2D occurs smoothly as a function of anisotropy, i.e. it
+is of the crossover type. Comparing the newly developed theory to the available
+experimental data on the heat capacity of $\rm{Cs}_2\rm{CuBr}_4$ and
+$\rm{Cs}_2\rm{CuCl}_4$ we extract the microscopic constants of the exchange
+interaction that previously could only be measured using inelastic neutron
+scattering in high magnetic fields.",1911.09403v1
+2019-12-09,Large Easy Axis Anisotropy in the One-Dimensional Magnet BaMo(PO$_4$)$_2$,"We present an extensive experimental and theoretical study on the
+low-temperature magnetic properties of the monoclinic anhydrous alum compound
+BaMo(PO$_4$)$_2$. The magnetic susceptibility reveals strong antiferromagnetic
+interactions $\theta_{CW} = -167$~K and long-range magnetic order at
+$T_N=22$~K, in agreement with a recent report. Powder neutron diffraction
+furthermore shows that the order is collinear, with the moments near the $ac$
+plane. Neutron spectroscopy reveals a large excitation gap $\Delta = 15$~meV in
+the low-temperature ordered phase, suggesting a much larger easy-axis spin
+anisotropy than anticipated. However, the large anisotropy justifies the
+relatively high ordered moment, N\'{e}el temperature, and collinear order
+observed experimentally, and is furthermore reproduced in a first principles
+calculations using a new computational scheme. We therefore propose
+BaMo(PO$_4$)$_2$ to host $S=1$ antiferromagnetic chains with large easy-axis
+anisotropy, which has been theoretically predicted to realize novel excitation
+continua.",1912.03969v1
+2019-12-10,Magnetic properties of thin epitaxial Pd$_{1-x}$Fe$_x$ alloy films,"In the paper we present the results of extensive studies of palladium-rich
+Pd1-xFex alloy films epitaxially grown on MgO single-crystal substrate. In a
+composition range of x = 0.01-0.07 these materials are soft ferromagnets, the
+saturation magnetization and magnetic anisotropy of which can be tuned by its
+composition. Vibrating sample magnetometry was used to study temperature
+dependences of spontaneous magnetic moment and to establish the temperature of
+magnetic ordering (Curie temperature). Ferromagnetic resonance (FMR)
+measurements at low temperatures in the in-plane and out-of-plane geometries
+revealed the four-fold in-plane magnetic anisotropy with the easy directions
+along the <110> axes of the substrate. The modelling of the angular dependence
+of the field for resonance allowed to extract the cubic and tetragonal
+contributions to the magnetic anisotropy of the films and establish their
+dependence on the concentration of iron in the alloy. Experimental data are
+discussed in the framework of existing theories of dilute magnetic alloys.
+Using the anisotropy constants established from FMR, the magnetic hysteresis
+loops are reproduced utilizing the Stoner-Wohlfarth model thus indicating the
+predominant coherent magnetic moment rotation at low temperatures. The obtained
+results compile a database of magnetic properties of a palladium-iron alloy
+considered as a material for superconducting spintronics.",1912.04852v1
+2019-12-17,Hyperbolic wavelet analysis of classical isotropic and anisotropic Besov-Sobolev spaces,"In this paper we introduce new function spaces which we call anisotropic
+hyperbolic Besov and Triebel-Lizorkin spaces. Their definition is based on a
+hyperbolic Littlewood-Paley analysis involving an anisotropy vector only
+occurring in the smoothness weights. Such spaces provide a general and natural
+setting in order to understand what kind of anisotropic smoothness can be
+described using hyperbolic wavelets (in the literature also sometimes called
+tensor-product wavelets), a wavelet class which hitherto has been mainly used
+to characterize spaces of dominating mixed smoothness.
+  A centerpiece of our present work are characterizations of these new spaces
+based on the hyperbolic wavelet transform. Hereby we treat both, the standard
+approach using wavelet systems equipped with sufficient smoothness, decay, and
+vanishing moments, but also the very simple and basic hyperbolic Haar system.
+  The second major question we pursue is the relationship between the novel
+hyperbolic spaces and the classical anisotropic Besov-Lizorkin-Triebel scales.
+As our results show, in general, both approaches to resolve an anisotropy do
+not coincide. However, in the Sobolev range this is the case, providing a link
+to apply the newly obtained hyperbolic wavelet characterizations to the
+classical setting. In particular, this allows for detecting classical
+anisotropies via the coefficients of a universal hyperbolic wavelet basis,
+without the need of adaption of the basis or a-priori knowledge on the
+anisotropy.",1912.08034v1
+2019-12-17,Whistler instabilities from the interplay of electron anisotropies in space plasmas: A quasilinear approach,"Recent statistical studies of observational data unveil relevant correlations
+between whistler fluctuations and the anisotropic electron populations present
+in space plasmas, e.g., solar wind and planetary magnetospheres. Locally,
+whistlers can be excited by two sources of free energy associated with
+anisotropic electrons, i.e., temperature anisotropies and beaming populations
+carrying the heat flux. However, these two sources of free energy and the
+resulting instabilities are usually studied independently preventing a
+realistic interpretation of their interplay. This paper presents the results of
+a parametric quasilinear study of the whistler instability cumulatively driven
+by two counter-drifting electron populations and their anisotropic
+temperatures. By comparison to individual regimes dominated either by beaming
+population or by temperature anisotropy, in a transitory regime the instability
+becomes highly conditioned by the effects of both these two sources of free
+energy. Cumulative effects stimulate the instability and enhance the resulting
+fluctuations, which interact with electrons and stimulate their diffusion in
+velocity space, leading to a faster and deeper relaxation of the beaming
+velocity associated with a core heating in perpendicular direction and a
+thermalization of the beaming electrons. In particular, the relaxation of
+temperature anisotropy to quasi-stable states below the thresholds conditions
+predicted by linear theory may explain the observations showing the
+accumulation of these states near the isotropy and equipartition of energy.",1912.09283v1
+2019-12-23,Fluctuation Dynamo in Collisionless and Weakly Collisional Magnetized Plasmas,"In weakly collisional astrophysical plasmas, such as the intracluster medium
+of galaxy clusters, the amplification of cosmic magnetic fields by chaotic
+fluid motions is hampered by the adiabatic production of magnetic-field-aligned
+pressure anisotropy. This anisotropy drives a viscous stress parallel to the
+field that inhibits the plasma's ability to stretch magnetic-field lines. I
+demonstrate through the use of kinetic simulations that in high-$\beta$
+plasmas, kinetic ion-Larmor scale instabilities sever the adiabatic link
+between the thermal and magnetic pressures, reducing this viscous stress and
+thereby allowing the dynamo to operate. Two distinct regimes of the fluctuation
+dynamo in a magnetized plasma are identified: one in which these instabilities
+efficiently regulate the pressure anisotropy and one in which this regulation
+is imperfect. I elucidate the role of these kinetic instabilities on the plasma
+viscosity and determine how the fields and flows self-organize to allow the
+dynamo to operate in the face of parallel viscous stresses. In the case of
+efficient pressure-anisotropy regulation, the plasma dynamo closely resembles
+its more traditional Pm ~ 1 MHD counterpart. When the regulation is imperfect,
+the dynamo exhibits characteristics remarkably similar to those found in the
+saturated state of the MHD dynamo. A novel set of microphysical closures for
+fluid simulations that bridges these two regimes are constructed, exhibiting
+explosive magnetic-field growth caused by a field-strength-dependent viscosity.
+The dynamos in both collisionless and weakly collisional plasmas are then
+closely compared to each other, revealing substantial differences in how
+sub-parallel viscous motions behave. The former (collisionless) scenario
+experiences a cascade of stretching motions to sub-Larmor scales that lead to
+increasingly fast dynamo as the magnetic Reynolds number is increased.",1912.11072v1
+2020-01-14,Anisotropic superconductivity mediated by ferroelectric fluctuations in cubic systems with spin-orbit coupling,"Motivated by the experimental observation that superconductivity in bulk
+doped SrTiO$_{3}$ is enhanced as a putative ferroelectric quantum critical
+point (FE-QCP) is approached, we study the pairing instability of a cubic
+system in which electrons exchange low-energy ferroelectric fluctuations.
+Instead of the gradient coupling to the lattice distortion associated with
+ferroelectricity, we consider a direct coupling between the electrons and the
+bosonic ferroelectric field that appears in the presence of spin-orbit
+coupling. Working in the weak-coupling regime, we find that the pairing
+interaction is dominated by the soft transverse optical (TO) mode, resulting in
+a $T_{c}$ enhancement upon approaching the FE-QCP. Focusing on even-parity
+states, we find that although the $s$-wave state always wins, states with
+higher Cooper-pair angular momentum become close competitors as the TO mode
+softens. We show that the cubic anisotropy of the FE fluctuations mixes the
+$s$-wave and $g$-wave states, resulting in a characteristic anisotropy of the
+gap function. The gap anisotropy behaves non-monotonically as the FE-QCP is
+approached: upon decreasing the TO mode frequency, the gap anisotropy first
+changes sign and then increases in magnitude. We discuss the possible
+applications of our results to the superconducting state of SrTiO$_{3}$.",2001.04919v1
+2020-04-07,Linear stability of magnetic vortex chains in a plasma in the presence of equilibrium electron temperature anisotropy,"The linear stability of chains of magnetic vortices in a plasma is
+investigated analytically in two dimensions by means of a reduced fluid model
+assuming a strong guide field and accounting for equilibrium electron
+temperature anisotropy. The chain of magnetic vortices is modelled by means of
+the classical ""cat's eyes"" solutions and the linear stability is studied by
+analysing the second variation of a conserved functional, according to the
+Energy-Casimir method. The stability analysis is carried out on the domain
+bounded by the separatrices of the vortices. Two cases are considered,
+corresponding to a ratio between perpendicular equilibrium ion and electron
+temperature much greater or much less than unity, respectively. In the former
+case, equilibrium flows depend on an arbitrary function. Stability is attained
+if the equilibrium electron temperature anisotropy is bounded from above and
+from below, with the lower bound corresponding to the condition preventing the
+firehose instability. A further condition sets an upper limit to the amplitude
+of the vortices, for a given choice of the equilibrium flow. For cold ions, two
+sub-cases have to be considered. In the first one, equilibria correspond to
+those for which the velocity field is proportional to the local Alfv\'en
+velocity. Stability conditions imply: an upper limit on the amplitude of the
+flow, which automatically implies firehose stability, an upper bound on the
+electron temperature anisotropy and again an upper bound on the size of the
+vortices. The second sub-case refers to equilibrium electrostatic potentials
+which are not constant on magnetic flux surfaces and the resulting stability
+conditions correspond to those of the first sub-case in the absence of flow.",2004.03243v2
+2020-04-27,Anisotropy driven reversal of magnetisation in Blume-Capel ferromagnet: A Monte Carlo study,"The two dimensional Spin-1 Blume-Capel ferromagnet is studied by Monte Carlo
+simulation with Metropolis algorithm. Starting from initial ordered spin
+configuration the reversal of magnetisation is investigated in presence of a
+magnetic field ($h$) applied in the opposite direction. The variations of the
+reversal time with the strength of single site anisotropy are investigated in
+details. The exponential dependence was observed. The systematic variations of
+the mean reversal time with positive and negative anisotropy was found. The
+mean macroscopic reversal time was observed to be linearly dependent on a
+suitably defined microscopic reversal time. The saturated magnetisation $M_f$
+after the reversal was noticed to be dependent of the strength of anisotropy
+$D$. An interesting scaling relation was obtained, $|M_f| \sim
+|h|^{\beta}f(D|h|^{-\alpha})$ with the scaling function of the form $f(x)=
+\frac{1}{1+e^{(x-a)/b}}$. The temporal evolution of density of $S_i^z=0$
+(surrounded by all $S_i^z=+1$) is observed to be exponentially decaying. The
+growth of mean density of $S_i^z=-1$ has been fitted in a function
+$\rho_{-1}(t) \sim \frac{1}{a+e^{(t_c-t)/c}}$. The characteristic time shows
+$t_c \sim e^{-rD}$ and a crossover in the rate of exponential falling is
+observed at $D=1.5$. The metastable volume fraction has been found to obey the
+Avrami's law.",2004.12586v4
+2020-05-18,A Detailed Examination of Anisotropy and Timescales in Three-dimensional Incompressible Magnetohydrodynamic Turbulence,"When magnetohydrodynamic turbulence evolves in the presence of a large-scale
+mean magnetic field, an anisotropy develops relative to that preferred
+direction. The well-known tendency is to develop stronger gradients
+perpendicular to the magnetic field, relative to the direction along the field.
+This anisotropy of the spectrum is deeply connected with anisotropy of
+estimated timescales for dynamical processes, and requires reconsideration of
+basic issues such as scale locality and spectral transfer. Here analysis of
+high-resolution three-dimensional simulations of unforced magnetohydrodynamic
+turbulence permits quantitative assessment of the behavior of theoretically
+relevant timescales in Fourier wavevector space. We discuss the distribution of
+nonlinear times, Alfv\'en times, and estimated spectral transfer rates.
+Attention is called to the potential significance of special regions of the
+spectrum, such as the two-dimensional limit and the ""critical balance"" region.
+A formulation of estimated spectral transfer in terms of a suppression factor
+supports a conclusion that the quasi two-dimensional fluctuations
+(characterized by strong nonlinearities) are not a singular limit, but may be
+in general expected to make important contributions.",2005.08815v2
+2020-05-19,Spin transport in a tunable Heisenberg model realized with ultracold atoms,"Simple models of interacting spins play an important role in physics. They
+capture the properties of many magnetic materials, but also extend to other
+systems, such as bosons and fermions in a lattice, systems with gauge fields,
+high-Tc superconductors, and systems with exotic particles such as anyons and
+Majorana fermions. In order to study and compare these models, a versatile
+platform is needed. Realizing such a system has been a long-standing goal in
+the field of ultracold atoms. So far, spin transport has only been studied in
+the isotropic Heisenberg model. Here we implement the Heisenberg XXZ model with
+adjustable anisotropy and use this system to study spin transport far from
+equilibrium after quantum quenches from imprinted spin helix patterns. In the
+non-interacting XX model, we find ballistic behavior of spin dynamics, while in
+the isotropic XXX model, we find diffusive behavior. For positive anisotropies,
+the dynamics ranges from anomalous super-diffusion to sub-diffusion depending
+on anisotropy, whereas for negative anisotropies, we observe a crossover in the
+time domain from ballistic to diffusive transport. This behavior contrasts with
+expectations for the linear response regime and raises new questions in
+understanding quantum many-body dynamics far away from equilibrium.",2005.09549v1
+2020-06-03,Combining ILC and moment expansion techniques for extracting average-sky signals and CMB anisotropies,"The method of weighted addition of multi-frequency maps, more commonly
+referred to as {\it Internal Linear Combination} (ILC), has been extensively
+employed in the measurement of cosmic microwave background (CMB) anisotropies
+and its secondaries along with similar application in 21cm data analysis. Here
+we argue and demonstrate that ILC methods can also be applied to data from
+absolutely-calibrated CMB experiments to extract average-sky signals in
+addition to the conventional CMB anisotropies. The performance of the simple
+ILC method is, however, limited, but can be significantly improved by adding
+constraints informed by physics and existing empirical information. In recent
+work, a moment description has been introduced as a technique of carrying out
+high precision modeling of foregrounds in the presence of inevitable averaging
+effects. We combine these two approaches to construct a heavily constrained
+form of the ILC, dubbed \milc, which can be used to recover tiny monopolar
+spectral distortion signals in the presence of realistic foregrounds and
+instrumental noise. This is a first demonstration for measurements of the
+monopolar and anisotropic spectral distortion signals using ILC and extended
+moment methods. We also show that CMB anisotropy measurements can be improved,
+reducing foreground biases and signal uncertainties when using the \milc. While
+here we focus on CMB spectral distortions, the scope extends to the 21cm
+monopole signal and $B$-mode analysis. We briefly discuss augmentations that
+need further study to reach the full potential of the method.",2006.02458v1
+2020-07-20,Electrical control of spin relaxation anisotropy during drift transport in a two-dimensional electron gas,"Spin relaxation was studied in a two-dimensional electron gas confined in a
+wide GaAs quantum well. Recently, the control of the spin relaxation anisotropy
+by diffusive motion was first shown in D. Iizasa et al., arXiv:2006.08253
+(2020). Here, we demonstrate electrical control by drift transport in a system
+with two-subbands occupied. The combined effect of in-plane and gate voltages
+was investigated using time-resolved Kerr rotation. The measured relaxation
+time present strong anisotropy with respect to the transport direction. For an
+in-plane accelerating electric field along $\left[110\right]$, the lifetime was
+strongly suppressed irrespective of the applied gate voltage. Remarkably, for
+transport along $\left[1\bar{1}0\right]$, the data shows spin lifetime that was
+gate-dependent and longer than in the $\left[110\right]$ direction regardless
+of the in-plane voltage. In agreement, independent results of anisotropic spin
+precession frequencies are also presented. Nevertheless, the long spin
+lifetime, strong anisotropy and drift response seen in the data are beyond the
+existing models for spin drift and diffusion.",2007.10425v2
+2020-07-31,Giant perpendicular magnetic anisotropy enhancement in MgO-based magnetic tunnel junction by using Co/Fe composite layer,"Magnetic tunnel junctions with perpendicular anisotropy form the basis of the
+spin-transfer torque magnetic random-access memory (STT-MRAM), which is
+non-volatile, fast, dense, and has quasi-infinite write endurance and low power
+consumption. Based on density functional theory (DFT) calculations, we propose
+an alternative design of magnetic tunnel junctions comprising
+Fe(n)Co(m)Fe(n)/MgO storage layers with greatly enhanced perpendicular magnetic
+anisotropy (PMA) up to several mJ/m2, leveraging the interfacial perpendicular
+anisotropy of Fe/MgO along with a stress-induced bulk PMA discovered within bcc
+Co. This giant enhancement dominates the demagnetizing energy when increasing
+the film thickness. The tunneling magnetoresistance (TMR) estimated from the
+Julliere model is comparable with that of the pure Fe/MgO case. We discuss the
+advantages and pitfalls of a real-life fabrication of the structure and propose
+the Fe(3ML)Co(4ML)Fe(3ML) as a storage layer for MgO-based STT-MRAM cells. The
+large PMA in strained bcc Co is explained in the framework of Bruno's model by
+the MgO-imposed strain and consequent changes in the energies of dyz and dz2
+minority-spin bands.",2007.15940v1
+2020-08-05,Whistler Waves and Electron Properties in the Inner Heliosphere: Helios Observations,"We present the analysis of narrowband whistler wave signatures observed in
+the inner heliosphere (0.3-1 au). These signatures are bumps in the spectral
+density in the 10-200 Hz frequency range of the AC magnetic field as measured
+by the search coil magnetometer on board the Helios1 spacecraft. We show that
+the majority of whistler signatures are observed in the slow solar wind (<500
+km/s) and their occurrence increases with the radial distance (R), from ~3% at
+0.3 au to ~10% at 0.9 au. In the fast solar wind (>600 km/s), whistler activity
+is significantly lower; whistler signatures start to appear for R > 0.6 au and
+their number increases from ~0.03% at 0.65 au to ~1% at 0.9 au. We have studied
+the variation of the electron core and halo anisotropy, as well as the electron
+normalized heat flux as a function of R and of the solar wind speed. We find
+that, in the slow wind electron core and halo anisotropy is higher than in fast
+one, and also that these anisotropies increase radially in both types of winds,
+which is in line with the occurrence of whistler signatures. We hypothesize the
+existence of a feedback mechanism to explain the observed radial variations of
+the occurrence of whistlers in relation with the halo anisotropy.",2008.02334v1
+2020-08-17,Precision Multi-Mode Dielectric Characterization of a Crystalline Perovskite Enables Determination of the Temperature-Dependent Phase Transitions,"Simple perovskite crystals undergo structural phase transitions on cooling to
+low temperatures, which significantly change the material properties of the
+crystal. In this work we rigorously characterize the temperature evolution of
+permittivity of a perovskite crystal as it undergoes phase transitions. In
+particular, we have undertaken precision measurements of a single crystal of
+Strontium Titanate from 294.6 K to 5.6 K, by measuring the frequency of
+multiple microwave transverse electric and magnetic resonant modes
+simultaneously. The multi-mode microwave measurement technique of resonant
+frequency used in this work allows high precision determination of any induced
+anisotropy of the permittivity as the crystal undergoes structural phase
+transitions. Compared with previous results we unequivocally show that the
+permittivity has an isotropic value of $316.3\pm2.2$ at room temperature,
+consistent with its well-known cubic structure, and determine the onset of
+dielectric anisotropy as the crystal is cooled to lower temperatures. We show
+that the crystal exhibits uniaxial anisotropy in the permittivity below 105 K
+when the structure becomes tetragonal, and exhibits biaxial anisotropy in the
+permittivity below 51 K when the structure becomes orthorhombic.",2008.07088v2
+2020-08-26,An effective parameterization of texture-induced viscous anisotropy in orthotropic materials with application for modeling geodynamical flows,"In this article, we describe the mathematical formulation and the numerical
+implementation of an effective parametrization of the viscous anisotropy of
+orthorhombic materials produced by crystallographic preferred orientations (CPO
+or texture), which can be integrated into 3D geodynamic and materials science
+codes. Here, the approach is applied to characterize the texture-induced
+viscous anisotropy of olivine polycrystals, the main constituent of the Earth's
+upper mantle. The parameterization is based on the Hill (1948) orthotropic
+yield criterion. The coefficients of the Hill yield surface are calibrated
+based on numerical tests performed using the second order Viscoplastic
+Self-consistent (SO-VPSC) model. The parametrization was implemented in a 3D
+thermo-mechanical finite-element code developed to model large-scale
+geodynamical flows, in the form of a Maxwell rheology combining isotropic
+elastic and anisotropic non-linear viscous behaviors. The implementation was
+validated by comparison with results of the analytical solution and of the
+SO-VPSC model for simple shear and axial compression of a homogeneous
+anisotropic material. An application designed to examine the effect of
+texture-induced viscous anisotropy on the reactivation of mantle shear zones in
+continental plates highlights unexpected couplings between localized
+deformation controlled by variations in the orientation and intensity of the
+olivine texture in the mantle and the mechanical behavior of the
+elasto-viscoplastic overlying crust. Importantly, the computational time only
+increases by a factor 2-3 with respect to the classic isotropic Maxwell
+viscoelastic rheology.",2008.11494v3
+2020-10-07,Correlation of uniaxial magnetic anisotropy axes and principal resistivities in polycrystalline ferromagnetic films,"In the present study, we demonstrate the measurement of resistivity tensor
+($\rho$) along the magnetic axes of a polycrystalline film of ferromagnetic
+permalloy (Py). To this end, conventional Hall-bar and a more recent extended
+van der Pauw methods were utilized for determining 2D $\rho$ in the film plane.
+The samples were prepared by normal incidence sputter deposition within an
+in-situ magnetic field to induce in-plane uniaxial magnetic anisotropy in the
+film. Since $\rho$ might be affected by the internal magnetization of the film,
+we performed measurements by rotation of a saturating magnetic field in the
+film plane. Both methods indicate that the average resistivity is lower along
+the easy axis of the film compared to the hard axis. Since X-ray diffraction
+results indicated no dominating texture in the film, we concluded that there is
+a correlation between uniaxial magnetic axes and principal resistivity axes.
+This is an important finding that allows determining the direction of magnetic
+anisotropy axes without magnetometry. The results also verify atomic or pair
+ordering to be the origin of uniaxial magnetic anisotropy in the Py since
+resistivity is sensitive to the level of order in solids. The extended van der
+Pauw utilized here can be easily performed on the as-received samples which is
+of practical interest.",2010.03554v3
+2020-10-10,Controlling the anisotropy of a van der Waals antiferromagnet with light,"Magnetic van der Waals materials provide an ideal playground for exploring
+the fundamentals of low-dimensional magnetism and open new opportunities for
+ultrathin spin processing devices. The Mermin-Wagner theorem dictates that as
+in reduced dimensions isotropic spin interactions cannot retain long-range
+correlations; the order is stabilized by magnetic anisotropy. Here, using
+ultrashort pulses of light, we demonstrate all-optical control of magnetic
+anisotropy in the two-dimensional van der Waals antiferromagnet NiPS$_3$.
+Tuning the photon energy in resonance with an orbital transition between
+crystal-field split levels of the nickel ions, we demonstrate the selective
+activation of a sub-THz two-dimensional magnon mode. The pump polarization
+control of the magnon amplitude confirms that the activation is governed by the
+instantaneous magnetic anisotropy axis emergent in response to photoexcitation
+of orbital states with a lowered symmetry. Our results establish pumping of
+orbital resonances as a universal route for manipulating magnetic order in
+low-dimensional (anti)ferromagnets.",2010.05062v1
+2020-11-02,Explaining Cosmological Anisotropy: Evidence for Causal Horizons from CMB data,"The origin of power asymmetry and other measures of statistical anisotropy on
+the largest scales of the universe, as manifested in Cosmic Microwave
+Background (CMB) and large-scale structure data, is a long-standing open
+question in cosmology. In this paper we analyze the Planck Legacy temperature
+anisotropy data and find strong evidence for a violation of the Cosmological
+principle of isotropy, with a probability of being a statistical fluctuation of
+order ~ 10^-9. The detected anisotropy is related to large-scale directional
+LCDM cosmological parameter variations across the CMB sky, that are sourced by
+three distinct patches in the maps with circularly-averaged sizes between 40 to
+70 degrees in radius. We discuss the robustness of our findings to different
+foreground separation methods and analysis choices, and find consistent results
+from WMAP data when limiting the analysis to the same scales. We argue that
+these well-defined regions within the cosmological parameter maps may reflect
+finite and casually disjoint horizons across the observable universe. In
+particular we show that the observed relation between horizon size and mean
+dark energy density within a given horizon is in good agreement with
+expectations from a recently proposed model of the universe that explains
+cosmic acceleration and cosmological parameter tensions between the high and
+low redshift universe from the existence of casual horizons within our
+universe.",2011.00910v4
+2020-11-04,Anisotropic Fermionic Quasiparticles,"We have carried out a comprehensive investigation of the quasiparticle
+properties of a two-dimensional electron gas, interacting via the long-range
+Coulomb interaction, in the presence of bare mass anisotropy (i.e. with an
+elliptic noninteracting Fermi surface) by calculating the self-energy, the
+spectral function, the scattering rate, and the effective mass within the
+leading order dynamical self-energy approximation. We find novel anisotropic
+features of quasiparticle properties that are not captured by the isotropic
+approximation where the anisotropic effective mass is replaced by the isotropic
+averaged density-of-states mass. Some of these interesting results are: (1) the
+renormalization of the quasiparticle spectrum becomes highly anisotropic as the
+quasiparticle energy increases away from the Fermi energy; (2) the inelastic
+scattering rate features a strong anisotropy, exhibiting an abrupt jump at
+different injected energies depending on the momentum direction of the injected
+electron; (3) the effective mass anisotropy is reduced by interactions. Our
+results and analysis show that the unjustified neglect of the mass anisotropy
+can lead to an incorrect description of quasiparticle properties of the
+anisotropic system although the use of an equivalent isotropic approximation
+using the density-of-states effective mass works as a reasonable approximation
+in many situations. We also provide a theory using the plasmon-pole
+approximation, commenting on its validity for anisotropic self-energy
+calculations. We comment also on the interaction effect on the Fermi surface
+topology, finding that the elliptic shape of the bare Fermi surface is
+preserved, with suppressed ellipticity, in the interacting system to a high
+degree of accuracy. Our theory provides a complete generalization of the
+existing isotropic many-body theory of interacting electrons to the
+corresponding anisotropic systems.",2011.02481v2
+2020-11-18,Breaking Beta: A comparison of mass modelling methods for spherical systems,"We apply four different mass modelling methods to a suite of publicly
+available mock data for spherical stellar systems. We focus on the recovery of
+the density and velocity anisotropy as a function of radius, using either
+line-of-sight velocity data only, or adding proper motion data. All methods
+perform well on isotropic and tangentially anisotropic mock data, recovering
+the density and velocity anisotropy within their 95% confidence intervals over
+the radial range 0.25 < R/Rhalf < 4, where Rhalf is the half light radius.
+However, radially-anisotropic mocks are more challenging. For line-of-sight
+data alone, only methods that use information about the shape of the velocity
+distribution function are able to break the degeneracy between the density
+profile and the velocity anisotropy to obtain an unbiased estimate of both.
+This shape information can be obtained through directly fitting a global phase
+space distribution function, by using higher order 'Virial Shape Parameters',
+or by assuming a Gaussian velocity distribution function locally, but
+projecting it self-consistently along the line of sight. Including proper
+motion data yields further improvements, and in this case, all methods give a
+good recovery of both the radial density and velocity anisotropy profiles.",2011.09493v2
+2020-11-19,The role of $T_0$ in CMB anisotropy measurements,"The quantity $T_0$, the cosmic microwave background (CMB) monopole, is an
+often neglected seventh parameter of the standard cosmological model. As well
+as its variation affecting the physics of the CMB, the measurement of $T_0$ is
+also used to calibrate the anisotropies, via the orbital dipole. We point out
+that it is easy to misestimate the effect of $T_0$ because the CMB anisotropies
+are conventionally provided in temperature units. In fact the anisotropies are
+most naturally described as dimensionless and we argue for restoring the
+convention of working with $\Delta T/T$ rather than $\Delta T$. As a free
+cosmological parameter, $T_0$ most naturally only impacts the CMB power spectra
+through late-time effects. Thus if we ignore the COBE-FIRAS measurement,
+current CMB data only weakly constrain $T_0$. Even ideal future CMB data can at
+best provide a percent-level constraint on $T_0$, although adding large-scale
+structure data will lead to further improvement. The FIRAS measurement is so
+precise that its uncertainty negligibly effects most, but not all, cosmological
+parameter inferences for current CMB experiments. However, if we eventually
+want to extract all available information from CMB power spectra measured to
+multipoles $\ell\simeq5000$, then we will need a better determination of $T_0$
+than is currently available.",2011.09616v2
+2020-11-20,Anisotropy of the spin-orbit coupling driven by a magnetic field in InAs nanowires,"We use the $\mathbf{k} \cdot \mathbf{p}$ theory and the envelope function
+approach to evaluate the Rashba spin-orbit coupling induced in a semiconductor
+nanowire by a magnetic field at different orientations, taking explicitely into
+account the prismatic symmetry of typical nano-crystals. We make the case for
+the strongly spin-orbit-coupled InAs semiconductor nanowires and investigate
+the anisotropy of the spin-orbit constant with respect to the field direction.
+At sufficiently high magnetic fields perpendicular to the nanowire, a 6-fold
+anisotropy results from the interplay between the orbital effect of field and
+the prismatic symmetry of the nanowire. A back-gate potential, breaking the
+native symmetry of the nano-crystal, couples to the magnetic field inducing a
+2-fold anisotropy, with the spin-orbit coupling being maximized or minimized
+depending on the relative orientation of the two fields. We also investigate
+in-wire field configurations, which shows a trivial 2-fold symmetry when the
+field is rotated off the axis. However, isotropic spin-orbit coupling is
+restored if a sufficiently high gate potential is applied. Our calculations are
+shown to agree with recent experimental analysis of the vectorial character of
+the spin-orbit coupling for the same nanomaterial, providing a microscopic
+interpretation of the latter.",2011.10483v1
+2020-12-07,Monopole Fluctuation of the CMB and its Gauge Invariance,"The standard theoretical description $\Theta(\hat n)$ of the observed CMB
+temperature anisotropies is gauge-dependent. It is, however, well known that
+the gauge mode is limited to the monopole and the higher angular multipoles
+$\Theta_l$ ($l\geq1$) are gauge-invariant. Several attempts have been made in
+the past to properly define the monopole fluctuation, but the resulting values
+of the monopole power $C_0$ are infinite due to the infrared divergences. The
+infrared divergences arise from the contribution of the uniform gravitational
+potential to the monopole fluctuation, in violation of the equivalence
+principle. Here we present the gauge-invariant theoretical description of the
+observed CMB temperature anisotropies and compute the monopole power
+$C_0=1.66\times10^{-9}$ in a $\Lambda$CDM model. While the gauge-dependence in
+the standard calculations originates from the ambiguity in defining the
+hypersurface for the background CMB temperature $\bar T$ today, it is in fact
+well defined and one of the fundamental cosmological parameters. We argue that
+once the cosmological parameters are chosen, the monopole fluctuation can be
+unambiguously inferred from the angle-average of the observed CMB temperature,
+making it a model-dependent ''observable''. Adopting simple approximations for
+the anisotropy formation, we derive a gauge-invariant analytical expression for
+the observed CMB temperature anisotropies to study the CMB monopole fluctuation
+and the cancellation of the uniform gravitational potential contributions on
+large scales.",2012.03968v2
+2020-12-08,Director alignment at the nematic-isotropic interface: elastic anisotropy and active anchoring,"Activity in nematics drives interfacial flows that lead to preferential
+alignment that is tangential or planar for extensile systems (pushers) and
+perpendicular or homeotropic for contractile ones (pullers). This alignment is
+known as active anchoring and has been reported for a number of systems and
+described using active nematic hydrodynamic theories. The latter are based on
+the one-elastic constant approximation, i.e., they assume elastic isotropy of
+the underlying passive nematic. Real nematics, however, have different elastic
+constants, which lead to interfacial anchoring. In this paper, we consider
+elastic anisotropy in multiphase and multicomponent hydrodynamic models of
+active nematics and investigate the competition between the interfacial
+alignment driven by the elastic anisotropy of the passive nematic and the
+active anchoring. We start by considering systems with translational invariance
+to analyze the alignment at flat interfaces and, then, consider two-dimensional
+systems and active nematic droplets. We investigate the competition of the two
+types of anchoring over a wide range of the other parameters that characterize
+the system. The results of the simulations reveal that the active anchoring
+dominates except at very low activities, when the interfaces are static. In
+addition, we found that the elastic anisotropy does not affect the dynamics but
+changes the active length that becomes anisotropic.",2012.04288v2
+2021-01-12,The Imprint of Large Scale Structure on the Ultra-High-Energy Cosmic Ray Sky,"Ultra-high-energy cosmic rays (UHECRs) are atomic nuclei from space with
+vastly higher energies than any other particles ever observed. Their origin and
+chemical composition remain a mystery. As we show here, the large- and
+intermediate-angular-scale anisotropies observed by the Pierre Auger
+Observatory are a powerful tool for understanding the origin of UHECRs. Without
+specifying any particular production mechanism, but only postulating that the
+source distribution follows the matter distribution of the local Universe, a
+good accounting of the magnitude, direction and energy dependence of the dipole
+anisotropy at energies above $8 \times 10^{18}$ eV is obtained, after taking
+into account the impact of energy losses during propagation (the ""GZK
+horizon""), diffusion in extragalactic magnetic field and deflections in the
+Galactic magnetic field (GMF). This is a major step toward the long-standing
+hope of using UHECR anisotropies to constrain UHECR composition and magnetic
+fields. The observed dipole anisotropy is incompatible with a pure proton
+composition in this scenario. With a more accurate treatment of energy losses,
+it should be possible to further constrain the cosmic-ray composition and
+properties of the extragalactic magnetic field, self-consistently improve the
+GMF model, and potentially expose individual UHECR sources.",2101.04564v3
+2021-01-11,On the interplay of solar wind proton and electron instabilities: Linear and quasi-linear approaches,"Important efforts are currently made for understanding the so-called kinetic
+instabilities, driven by the anisotropy of different species of plasma
+particles present in the solar wind and terrestrial magnetosphere. These
+instabilities are fast enough to efficiently convert the free energy of plasma
+particles into enhanced (small-scale) fluctuations with multiple implications,
+regulating the anisotropy of plasma particles. In this paper we use both linear
+and quasilinear (QL) frameworks to describe complex unstable regimes, which
+realistically combine different temperature anisotropies of electrons and ions
+(protons). Thus parameterized are various instabilities, e.g., proton and
+electron firehose, electromagnetic ion cyclotron, and whistler instability,
+showing that their main linear properties are markedly altered by the interplay
+of anisotropic electrons and protons. Linear theory may predict a strong
+competition of two instabilities of different nature when their growth rates
+are comparable. In the QL phase wave fluctuations grow and saturate at
+different levels and temporal scales, by comparison to the individual
+excitation of the proton or electron instabilities. In addition, cumulative
+effects of the combined proton and electron induced fluctuations can markedly
+stimulate the relaxations of their temperature anisotropies. Only whistler
+fluctuations inhibit the efficiency of proton firehose fluctuations in the
+relaxation of anisotropic protons. These results offer valuable premises for
+further investigations in numerical simulations, to decode the full spectrum of
+kinetic instabilities resulting from the interplay of anisotropic electrons and
+protons in space plasmas.",2101.07689v1
+2021-02-19,Improved large scales interstellar dust foreground model and CMB solar dipole measurement,"The Cosmic Microwave Background anisotropies are difficult to measure at
+large angular scales. In this paper, we present a new analysis of the \Planck\
+High Frequency Instrument data that brings the cosmological part and its major
+foreground signal close to the detector noise. The solar dipole signal, induced
+by the motion of the solar system with respect to the CMB, is a very efficient
+tool to calibrate a detector or a set of detectors with high accuracy. In this
+work, the solar dipole signal is used to extract corrections of the frequency
+maps offsets reducing significantly uncertainties. The solar dipole parameters
+are refined together with the improvement of the high frequency foregrounds,
+and of the CMB large scales cosmological anisotropies. The stability of the
+solar dipole parameters is a powerful way to control the galactic foregrounds
+removal in the component separation process. It is used to build a model for
+Spectral Energy Distribution spatial variations of the interstellar dust
+emission. The knowledge of these variations will help future CMB analyses in
+intensity, and also in polarization to measure faint signal related to the
+optical reionization depth and the tensor-to-scalar ratio of the primordial
+anisotropies. The results of this work are: improved solar dipole parameters, a
+new interstellar dust model, and a large scale cosmological anisotropies map.",2102.10004v1
+2021-02-22,Anisotropic cosmological models in Horndeski gravity,"It was found recently that the anisotropies in the homogeneous Bianchi I
+cosmology considered within the context of a specific Horndeski theory are
+damped near the initial singularity instead of being amplified. In this work we
+extend the analysis of this phenomenon to cover the whole of the Horndeski
+family. We find that the phenomenon is absent in the K-essence and/or Kinetic
+Gravity Braiding theories, where the anisotropies grow as one approaches the
+singularity. The anisotropies are damped at early times only in more general
+Horndeski models whose Lagrangian includes terms quadratic and cubic in second
+derivatives of the scalar field. Such theories are often considered as being
+inconsistent with the observations because they predict a non-constant speed of
+gravitational waves. However, the predicted value of the speed at present can
+be close to the speed of light with any required precision, hence the theories
+actually agree with the present time observations. We consider two different
+examples of such theories, both characterized by a late self-acceleration and
+an early inflation driven by the non-minimal coupling. Their anisotropies show
+a maximum at intermediate times and approach zero at early and late times. The
+early inflationary stage exhibits an instability with respect to inhomogeneous
+perturbations, suggesting that the initial state of the universe should be
+inhomogeneous. However, more general Horndeski models may probably be stable.",2102.10981v2
+2021-02-27,Strong bulk-surface interaction dominated in-plane anisotropy of electronic structure in GaTe,"Recently, intriguing physical properties have been unraveled in anisotropic
+layered semiconductors, in which the in-plane electronic band structure
+anisotropy often originates from the low crystallographic symmetry and thus a
+thickness-independent character emerges. Here, we apply high-resolution
+angle-resolved photoemission spectroscopy to directly image the in-plane
+anisotropic energy bands in monoclinic gallium telluride (GaTe). Our
+first-principles calculations reveal the in-plane anisotropic energy band
+structure of GaTe measured experimentally is dominated by a strong bulk-surface
+interaction rather than geometric factors, surface effect and quantum
+confinement effect. Furthermore, accompanied by the thickness of GaTe
+increasing from mono- to few-layers, the strong interlayer coupling of GaTe
+induces direct-indirect-direct band gap transitions and the in-plane anisotropy
+of hole effective mass is reversed. Our results shed light on the physical
+origins of in-plane anisotropy of electronic structure in GaTe, paving the way
+for the design and device applications of nanoelectronics and optoelectronics
+based on anisotropic layered semiconductors.",2103.00272v4
+2021-03-05,Microstructural origins of crushing strength for inherently anisotropic brittle materials,"We study the crushing strength of brittle materials whose internal structure
+(e.g., mineral particles or graining) presents a layered arrangement
+reminiscent of sedimentary and metamorphic rocks. Taking a discrete-element
+approach, we probe the failure strength of circular-shaped samples intended to
+reproduce specific mineral configurations. To do so, assemblies of cells,
+products of a modified Voronoi tessellation, are joined in mechanically-stable
+layerings using a bonding law. The cells' shape distribution allows us to set a
+level of inherent anisotropy to the material. Using a diametral point loading,
+and systematically changing the loading orientation with respect to the cells'
+configuration, we characterize the failure strength of increasingly anisotropic
+structures. This approach ends up reproducing experimental observations and
+lets us quantify the statistical variability of strength, the consumption of
+the fragmentation energy, and the induced anisotropies linked to the cell's
+geometry and force transmission in the samples. Based on a fine description of
+geometrical and mechanical properties at the onset of failure, we develop a
+micromechanical breakdown of the crushing strength variability using an
+analytical decomposition of the stress tensor and the geometrical and force
+anisotropies. We can conclude that the origins of failure strength in
+anisotropic layered media rely on compensations of geometrical and mechanical
+anisotropies, as well as an increasing average radial force between minerals
+indistinctive of tensile or compressive components.",2103.03962v1
+2021-03-10,Stochastic Electron Acceleration by Temperature Anisotropy Instabilities Under Solar Flare Plasma Conditions,"Using 2D particle-in-cell (PIC) plasma simulations we study electron
+acceleration by temperature anisotropy instabilities, assuming conditions
+typical of above-the-loop-top (ALT) sources in solar flares. We focus on the
+long-term effect of $T_{e,\perp} > T_{e,\parallel}$ instabilities by driving
+the anisotropy growth during the entire simulation time, through imposing a
+shearing or a compressing plasma velocity ($T_{e,\perp}$ and $T_{e,\parallel}$
+are the temperatures perpendicular and parallel to the magnetic field). This
+magnetic growth makes $T_{e,\perp}/T_{e,\parallel}$ grow due to electron
+magnetic moment conservation, and amplifies the ratio $\omega_{ce}/\omega_{pe}$
+from $\sim 0.53$ to $\sim 2$ ($\omega_{ce}$ and $\omega_{pe}$ are the electron
+cyclotron and plasma frequencies, respectively). In the regime
+$\omega_{ce}/\omega_{pe}\lesssim 1.2-1.7$ the instability is dominated by
+oblique, quasi-electrostatic (OQES) modes, and the acceleration is inefficient.
+When $\omega_{ce}/\omega_{pe}$ has grown to $\omega_{ce}/\omega_{pe}\gtrsim
+1.2-1.7$, electrons are efficiently accelerated by the inelastic scattering
+provided by unstable parallel, electromagnetic z (PEMZ) modes. After
+$\omega_{ce}/\omega_{pe}$ reaches $\sim 2$, the electron energy spectra show
+nonthermal tails that differ between the shearing and compressing cases. In the
+shearing case, the tail resembles a power-law of index $\alpha_s \sim$ 2.9 plus
+a high-energy bump reaching $\sim 300$ keV. In the compressing runs, $\alpha_s
+\sim$ 3.7 with a spectral break above $\sim 500$ keV. This difference can be
+explained by the different temperature evolutions in these two types of
+simulations, suggesting a critical role played by the type of anisotropy
+driving, $\omega_{ce}/\omega_{pe}$ and the electron temperature in the
+efficiency of the acceleration.",2103.05805v2
+2021-04-01,The oscillatory anisotropy in the spatially flat cosmological models,"In this manuscript, we investigate the oscillatory behaviour of the
+anisotropy in the diagonal Bianchi-I spacetimes. Our starting point is a
+simplification of Einstein's equations using only observable or physical
+variables. As a consequence, we are able to: (a) Prove general results
+concerning the existence of oscillations of the anisotropy in the primordial
+and the late-time universe. For instance, in the expanding scenario, we show
+that a past weakly mixmaster behaviour (oscillations as we approach the Kasner
+solutions) might appear even with no violation of the usual energy conditions,
+while in the future, the pulsation (oscillations around isotropic solutions)
+seems to be most favored; (b) Determine a large scheme for deriving classes of
+physically motivated exact solutions, and we give some (including the general
+barotropic perfect fluid and the magnetic one); (c) Understand the physical
+conditions for the occurrence of the isotropization or anisotropization during
+the cosmological evolution; (d) Understand how anisotropy and energy density
+are converted one into another. In particular, we call attention to the
+presence of a residue in the energy density in a late-time isotropic universe
+coming from its past anisotropic behaviour.",2104.00470v1
+2021-05-09,Constraining the anisotropy of the Universe with the X-ray and UV fluxes of quasars,"We test the anisotropy in the Finslerian cosmological model with the X-ray
+and ultraviolet (UV) fluxes of 808 quasars. The dipole amplitude is
+$A_D=0.302_{ -0.124}^{ +0.185}$ and the dipole direction points towards $(l, b)
+= ( 288.92_{~ -28.80^{\circ}}^{^{\circ}+23.74^{\circ}}, 6.10_{~
+-16.40^{\circ}}^{^{\circ} +16.55^{\circ}} )$. We find that the dipole direction
+from the X-ray and UV fluxes of quasars is very close to the dipole direction
+given by the ""Joint Light-curve Analysis"" (JLA) compilation in the Finslerian
+cosmological model and the angular difference between the two dipole directions
+is only $10.44^{\circ}$. We also find the angular difference between the dipole
+direction from the 808 quasars in the Finslerian cosmological model and ones
+from the supernovae of type Ia (SNe Ia) samples in the dipole-modulated
+$\Lambda$CDM model is around $30^{\circ}$. Six gravitationally lensed quasars
+are considered to investigate the Hubble constant $H_0$ in the Finslerian
+cosmological model. We get a slightly smaller $H_0$ than the result given by
+the six gravitationally lensed quasars. Finally, we forecast the future
+constraints on the dipole parameters with the X-ray and UV fluxes of quasars.
+As the number of simulations increases, the precisions of the parameters
+related to anisotropy in the Finslerian cosmological model improve
+significantly. The X-ray and UV fluxes of quasars have a promising future as a
+probe of anisotropy in Finsler spacetime.",2105.03965v1
+2021-05-22,Estimation of lunar surface dielectric constant using MiniRF SAR data,"A new model has been developed to estimate the dielectric constant of the
+lunar surface using Synthetic Aperture Radar (SAR) data. Continuous
+investigation on the dielectric constant of the lunar surface is a high
+priority task due to future lunar mission's goals and possible exploration of
+human outposts. For this purpose, derived anisotropy and backscattering
+coefficients of SAR images are used. The SAR images are obtained from Miniature
+Radio Frequency (MiniRF) radar onboard Lunar Reconnaissance Orbiter (LRO).
+These images are available in the form of Stokes parameters, which are used to
+derive the coherency matrix. The derived coherency matrix is further
+represented in terms of particle anisotropy. This coherency matrix's elements
+compared with Cloud's coherency matrix, which results in the new relationship
+between particle anisotropy and coherency matrix elements (backscattering
+coefficients). Following this, estimated anisotropy is used to determine the
+dielectric constant. Our model estimates the dielectric constant of the lunar
+surface without parallax error. The produce results are also comparable with
+the earlier estimate. As an advantageous, our method estimates the dielectric
+constant without any apriori information about the density or composition of
+lunar surface materials. The proposed approach can also be useful for
+determining the dielectric properties of Mars and other celestial bodies.",2105.10670v1
+2021-05-25,"Power Anisotropy, Dispersion Signature and Turbulence Diffusion Region in the 3D Wavenumber Domain of Space Plasma Turbulence","We explore the multi-faceted important features of turbulence (e.g.,
+anisotropy, dispersion, diffusion) in the three-dimensional (3D) wavenumber
+domain ($k_\parallel$, $k_{\perp,1}$, $k_{\perp,2}$), by employing the
+k-filtering technique to the high-quality measurements of fields and particles
+from the MMS multi-spacecraft constellation. We compute the 3D power spectral
+densities (PSDs) of magnetic and electric fluctuations (marked as
+$\rm{PSD}(\delta \mathbf{B}(\mathbf{k}))$ and $\rm{PSD}(\delta
+\mathbf{E}'_{\langle\mathbf{v}_\mathrm{i}\rangle}(\mathbf{k}))$), both of which
+show a prominent spectral anisotropy in the sub-ion range. We give the first 3D
+image of the bifurcation between power spectra of the electric and magnetic
+fluctuations, by calculating the ratio between $\rm{PSD}(\delta \mathbf{E}'_{
+\langle\mathbf{v}_\mathrm{i}\rangle}(\mathbf{k}))$ and $\rm{PSD}(\delta
+\mathbf{B}(\mathbf{k}))$, the distribution of which is related to the
+non-linear dispersion relation. We also compute the ratio between electric
+spectra in different reference frames defined by the ion bulk velocity, that is
+$\mathrm{PSD}(\delta{\mathbf{E}'_{\mathrm{local}\
+\mathbf{v}_\mathrm{i}}})/\mathrm{PSD}(\delta{\mathbf{E}'_{
+\langle\mathbf{v}_\mathrm{i}\rangle}})$, to visualize the turbulence ion
+diffusion region (T-IDR) in wavenumber space. The T-IDR has an anisotropy and a
+preferential direction of wavevectors, which is generally consistent with the
+plasma wave theory prediction based on the dominance of kinetic Alfv\'en waves
+(KAW). This work manifests the worth of the k-filtering technique in diagnosing
+turbulence comprehensively, especially when the electric field is involved.",2105.12568v1
+2021-06-03,Effect of pseudogap on electronic anisotropy in the strain dependence of the superconducting $T_c$ of underdoped YBa$_2$Cu$_3$O$_y$,"For orthorhombic superconductors we define thermodynamic anisotropy $N \equiv
+d T_c/d \epsilon_{22} - dT_c/d \epsilon_{11}$ as the difference in how
+superconducting $T_c$ varies with strains $\epsilon_{ii}$, $i=(1, 2)$, along
+the in-plane directions. We study the hole doping ($p$) dependence of $N$ on
+detwinned single crystals of underdoped YBa$_2$Cu$_3$O$_y$ (YBCO) using
+ultrasound technique. While the structural orthorhombicity of YBCO reduces
+monotonically with decreasing doping over $0.065 <p<0.16$, we find that the
+thermodynamic anisotropy shows an intriguing enhancement at intermediate doping
+level, which is of electronic origin. Our theoretical analysis shows that the
+enhancement of the electronic anisotropy can be related to the pseudogap
+potential in the electronic specturm that itself increases when the Mott
+insulating state is approached. Our results imply that the pseudogap is
+controlled by a local energy scale that can be tuned by varying the nearest
+neighbor Cu-Cu bond length. Our work opens the possibility to strain engineer
+the pseudogap potential to enhance the superconducting \Tc.",2106.02055v2
+2021-06-09,A new way to test the Cosmological Principle: measuring our peculiar velocity and the large scale anisotropy independently,"We present a novel approach to disentangle two key contributions to the
+largest-scale anisotropy of the galaxy distribution: (i) the intrinsic dipole
+due to clustering and anisotropic geometry, and (ii) the kinematic dipole due
+to our peculiar velocity. Including the redshift and angular size of galaxies,
+in addition to their fluxes and positions allows us to measure both the
+direction and amplitude of our velocity independently of the intrinsic dipole
+of the source distribution. We find that this new approach applied to future
+galaxy surveys (LSST and Euclid) and a SKA radio continuum survey will allow to
+measure our velocity ($\beta = v/c$) with a relative error in the amplitude
+$\sigma(\beta)/\beta \sim (1.3 - 4.5)\%$ and in direction, $\theta_{\beta} \sim
+0.9^\circ - 3.9^\circ$, well beyond what can be achieved when analysing only
+the number count dipole. We also find that galaxy surveys are able to measure
+the intrinsic large-scale anisotropy with a relative uncertainty of $\lesssim
+5\%$ (measurement error, not including cosmic variance). Our method enables two
+simultaneous tests of the Cosmological Principle: comparing the observations of
+our peculiar velocity with the CMB dipole, and testing for a significant
+intrinsic anisotropy on large scales which would indicate effects beyond the
+standard cosmological model.",2106.05284v2
+2021-06-27,Relaxation in Ordered Assembly of Magnetic Nanoparticles,"We study the relaxation characteristics in the two-dimensional ($l^{}_x
+\times l^{}_y$) array of magnetic nanoparticles (MNPs) as a function of aspect
+ratio $A^{}_r=l^{}_y/l^{}_x$, dipolar interaction strength $h^{}_d$ and
+anisotropy axis orientation using computer simulation. The anisotropy axes of
+all the MNPs are assumed to have the same direction, $\alpha$ being the
+orientational angle. Irrespective of $\alpha$ and $A^{}_r$, the functional form
+of the magnetization-decay curve is perfectly exponentially decaying with
+$h^{}_d\leq0.2$. There exists a transition in relaxation behaviour at
+$h^{}_d\approx0.4$; magnetization relaxes slowly for $\alpha\leq45^\circ$; it
+relaxes rapildy with $\alpha>45^\circ$. Interestingly, it decays rapidly for
+$h^{}_d>0.6$, irrespective of $\alpha$. It is because the dipolar interaction
+promotes antiferromagnetic coupling in such cases. There is a strong effect of
+$\alpha$ on the magnetic relaxation in the highly anisotropic system
+($A^{}_r\geq25$). Interesting physics unfolds in the case of a huge aspect
+ratio $A^{}_r=400$. There is a rapid decay of magnetization with $\alpha$, even
+for weakly interacting MNPs. Remarkably, magnetization does not relax even with
+a moderate value of $h^{}_d=0.4$ and $\alpha=0^\circ$ because of ferromagnetic
+coupling dominance. Surprisingly, there is a complete magnetization reversal
+from saturation (+1) to $-1$ state with $\alpha>60^\circ$. The dipolar field
+and anisotropy axis tend to get aligned antiparallel to each other in such a
+case. The effective N\'eel relaxation time $\tau^{}_N$ depends weakly on
+$\alpha$ for small $h^{}_d$ and $A^{}_r\leq25.0$. For large $A^{}_r$, there is
+a rapid fall in $\tau^{}_N$ as $\alpha$ is incremented from 0 to $90^\circ$.
+These results benefit applications in data and energy storages where such
+controlled magnetization alignment and desired structural anisotropy are
+desirable.",2106.14271v1
+2021-07-16,Giant Anisotropic in-Plane Thermal Conduction Induced by Anomalous Phonons in Nearly-Equilaterally Structured PdSe2,"In two-dimensional materials, structure difference induces the difference in
+phonon dispersions, leading to the anisotropy of in-plane thermal transport.
+Here, we report an exceptional case in layered PdSe2, where the bonding, force
+constants, and lattice constants are nearly-equal along the in-plane
+crystallographic axis directions. The phonon dispersions show significant
+differences between the Gamma-X and Gamma-Y directions, leading to the
+anisotropy of in-plane thermal conductivity with a ratio up to 1.8. Such
+anisotropy is not only unexpected in equilaterally structured (in-plane)
+materials but also comparable to the record in the non-equilaterally structured
+material reported to date. By combining inelastic X-ray scattering and
+first-principles calculations, we attribute such anisotropy to the low-energy
+phonons along Gamma-X, in particular, their lower group velocities and
+""avoided-crossing"" behavior. The different bucking structures between a-
+(zigzag-type) and b-axis (flat-type) are mainly responsible for the unique
+phonon dynamics properties of PdSe2. The present results illustrate the unusual
+thermal conduction mechanism of the equilaterally structured materials and
+provide valuable insights on thermal management in electronic devices.",2107.07959v1
+2021-09-13,Magnetic anisotropy of the van der Waals ferromagnet Cr$_2$Ge$_2$Te$_6$ studied by angular-dependent XMCD,"The van der Waals ferromagnet Cr$_2$Ge$_2$Te$_6$ (CGT) has a two-dimensional
+crystal structure where each layer is stacked through van der Waals force. We
+have investigated the nature of the ferromagnetism and the weak perpendicular
+magnetic anisotropy (PMA) of CGT by means of X-ray absorption spectroscopy and
+X-ray magnetic circular dichroism (XMCD) studies of CGT single crystals. The
+XMCD spectra at the Cr $L_{2,3}$ edge for different magnetic field directions
+were analyzed on the basis of the cluster-model multiplet calculation. The Cr
+valence is confirmed to be 3+ and the orbital magnetic moment is found to be
+nearly quenched, as expected for the high-spin $t_{2g}$$^3$ configuration of
+the Cr$^{3+}$ ion. A large ($\sim 0.2$ eV) trigonal crystal-field splitting of
+the $t_{2g}$ level caused by the distortion of the CrTe$_6$ octahedron has been
+revealed, while the single-ion anisotropy (SIA) of the Cr atom is found to have
+a sign {\it opposite} to the observed PMA and too weak compared to the reported
+anisotropy energy. The present result suggests that anisotropic exchange
+coupling between the Cr atoms through the ligand Te $5p$ orbitals having strong
+spin-orbit coupling has to be invoked to explain the weak PMA of CGT, as in the
+case of the strong PMA of CrI$_3$.",2109.05715v1
+2021-10-06,"Stacking-order effect on spin-orbit torque, spin-Hall magnetoresistance, and magnetic anisotropy in Ni$_{81}$Fe$_{19}$-IrO$_2$ bilayers","The 5d transition-metal oxides have been an intriguing platform to
+demonstrate efficient charge to spin current conversion due to a unique
+electronic structure dominated by strong spin-orbit coupling. Here, we report
+on stacking-order effect of spin-orbit torque (SOT), spin-Hall
+magnetoresistance, and magnetic anisotropy in bilayer Ni$_{81}$Fe$_{19}$-5d
+iridium oxide, IrO$_2$. While all the IrO$_2$ and Pt control samples exhibit
+large dampinglike-SOT generation stemming from the efficient charge to spin
+current conversion, the magnitude of the SOT is larger in the IrO$_2$
+(Pt)-bottom sample than in the IrO$_2$ (Pt)-top one. The fieldlike-SOT has even
+more significant stack order effect, resulting in an opposite sign in the
+IrO$_2$ samples in contrast to the same sign in the Pt samples. Furthermore, we
+observe that the magnetic anisotropy energy density and the anomalous Hall
+effect are increased in the IrO$_2$ (Pt)-bottom sample, suggesting enhanced
+interfacial perpendicular magnetic anisotropy. Our findings highlight the
+significant influence of the stack order on spin transport and magnetotransport
+properties of Ir oxide/ferromagnet systems, providing useful information on
+design of SOT devices including 5d transition-metal oxides.",2110.02517v1
+2021-10-27,Geometry of Magnetic Fluctuations near the Sun from PSP,"Solar wind magnetic fluctuations exhibit anisotropy due to the presence of a
+mean magnetic field in the form of the Parker spiral. Close to the Sun, direct
+measurements were not available until the recently launched Parker Solar Probe
+(PSP) mission. The nature of anisotropy and geometry of the magnetic
+fluctuations play a fundamental role in dissipation processes and in the
+transport of energetic particles in space. Using PSP data, we present
+measurements of geometry and anisotropy of the inner heliosphere magnetic
+fluctuations, from fluid to kinetic scales. The results are surprising and
+different from 1 au observations. We find that fluctuations evolve
+characteristically with size scale. However, unlike 1 au solar wind, at the
+outer scale, the fluctuations are dominated by wavevectors quasi-parallel to
+the local magnetic field. In the inertial range, average wave vectors become
+less field-aligned, but still remain more field aligned than near-Earth solar
+wind. In the dissipation range, the wavevectors become almost perpendicular to
+the local magnetic field in the dissipation range, to a much higher degree than
+those indicated by 1 au observations. We propose that this reduced degree of
+anisotropy in the outer scale and inertial range is due to the nature of
+large-scale forcing outside the solar corona.",2110.14756v1
+2021-10-26,CLASS_GWB: robust modeling of the astrophysical gravitational wave background anisotropies,"Gravitational radiation offers a unique possibility to study the large-scale
+structure of the Universe, gravitational wave sources and propagation in a
+completely novel way. Given that gravitational wave maps contain a wealth of
+astrophysical and cosmological information, interpreting this signal requires a
+non-trivial multidisciplinary approach. In this work we present the complete
+computation of the signal produced by compact object mergers accounting for a
+detailed modelling of the astrophysical sources and for cosmological
+perturbations. We develop the CLASS_GWB code, which allows for the computation
+of the anisotropies of the astrophysical gravitational wave background,
+accounting for source and detector properties, as well as effects of
+gravitational wave propagation. We apply our numerical tools to robustly
+compute the angular power spectrum of the anisotropies of the gravitational
+wave background generated by astrophysical sources in the LIGO-Virgo frequency
+band. The end-to-end theoretical framework we present can be easily applied to
+different sources and detectors in other frequency bands. Moreover, the same
+numerical tools can be used to compute the anisotropies of gravitational wave
+maps of the sky made using resolved events.",2110.15059v1
+2021-11-15,Probing magnetic anisotropy in Kagome antiferromagnetic Mn$_3$Ge with torque magnetometry,"We investigate the magnetic symmetry of the topological antiferromagnetic
+material Mn$_3$Ge by using torque measurements. Below the Neel temperature,
+detailed angle-dependent torque measurements were performed on Mn$_3$Ge single
+crystals in directions parallel and perpendicular to the Kagome basal plane.
+The out-of plane torque data exhibit $\pm\sin\theta$ and $\sin2\theta$
+behaviors, of which the former results from the spontaneous ferromagnetism
+within the basal plane and the latter from the in- and out-of-plane
+susceptibility anisotropy. The reversible component of the in-plane torque
+exhibits $\sin6\varphi$ behavior, revealing the six-fold symmetry of the
+in-plane magnetic free energy. Moreover, we find that the free energy minima
+are pinned to the direction of spontaneous ferromagnetism, which correspond to
+the maxima of the irreversible component of the in-plane torque. We provide an
+effective spin model to describe the in-plane magnetic anisotropy. Our results
+demonstrate that the ground state of Mn$_3$Ge is described by the coexistence
+of a strong six-fold antichiral order and a weak ferromagnetic order induced by
+second-order spin anisotropy.",2111.07587v2
+2021-12-20,Temperature independent pseudogap from $^{17}$O and $^{89}$Y NMR and the single component picture,"Nuclear Magnetic Resonance (NMR) is a powerful local quantum probe of the
+electronic structure of materials, but in the absence of reliable theory the
+interpretation of the NMR data can be challenging. This is true in particular
+for the cuprate high-temperature superconductors. Over the years, a large base
+of NMR data became available, which makes a review of the early interpretation
+possible. Recently, it was shown that all planar $^{17}$O NMR shift and
+relaxation data available in the literature point to a temperature independent
+but doping dependent pseudogap, very similar to what was proposed from the
+electronic entropy. Here we analyze the anisotropy of the shift and relaxation
+of planar O to establish whether a single electronic spin component is
+applicable, since the planar Cu shift anisotropy clearly fails such a
+description. We find that the orbital shift terms deduced from the data are in
+agreement with first principle calculations, and the shift data show a
+temperature independent anisotropy also in agreement with hyperfine
+coefficients predicted by first principles, which also account for the
+relaxation anisotropy. Furthermore, we show that the original $^{89}$Y shift
+and relaxation data are in agreement with the proposed temperature independent
+pseudogap. This pseudogap depends on doping, but also on the family of
+materials, and the density of states outside or in the absence of the gap is
+universal for the cuprates; this suggests that the entropy should be similar
+for all cuprates, as well. Further consequences will be discussed.",2112.10595v1
+2021-12-21,CrSbSe3: a pseudo one-dimensional ferromagnetic semiconductor,"Low-dimensional magnetic materials have attracted much attention due to their
+novel properties and high potential for spintronic applications. In this work,
+we study the electronic structure and magnetic properties of the pseudo
+one-dimensional compound CrSbSe$_3$, using density functional calculations,
+superexchange model analyses, and Monte Carlo simulations. We find that
+CrSbSe$_3$ is a ferromagnetic (FM) semiconductor with a band gap of about 0.65
+eV. The FM couplings within each zig-zag spin chain are due to the Cr-Se-Cr
+superexchange with the near-90$^\circ$ bonds, and the inter-chain FM couplings
+are one order of magnitude weaker. By inclusion of the spin-orbit coupling
+(SOC) effects, our calculations reproduce the experimental observation of the
+easy magnetization $a$ axis and the hard $b$ axis (the spin-chain direction),
+with the calculated moderate magnetic anisotropy of 0.19 meV/Cr. Moreover, we
+identify the nearly equal contributions from the single ion anisotropy of Cr,
+and from the exchange anisotropy due to the strong SOC of the heavy elements Sb
+and Se and their couplings with Cr. Using the parameters of the magnetic
+coupling and anisotropy from the above calculations, our Monte Carlo
+simulations yield the Curie temperature $T_{\rm{C}}$ of 108 K.",2112.10937v1
+2022-01-25,Doppler boosting the stochastic gravitational wave background,"One of the guaranteed features of the stochastic gravitational wave
+background (SGWB) is the presence of Doppler anisotropies induced by the motion
+of the detector with respect to the rest frame of the SGWB source. We point out
+that kinematic effects can be amplified if the SGWB is characterised by large
+tilts in its spectrum as a function of frequency, or by sizeable intrinsic
+anisotropies. Hence we examine the possibility to use Doppler effects as
+complementary probes of the SGWB frequency profile. For this purpose we work in
+multipole space, and we study the effect of kinematic modulation and aberration
+on the GW energy density parameter and on its angular power spectrum. We
+develop a Fisher forecast analysis and we discuss prospects for constraining
+parameters controlling kinematically induced anisotropies with future detector
+networks. As a case study, we apply our framework to a background component
+with constant slope in frequency, potentially detectable by a network of future
+ground-based interferometers. For this specific example, we show that a
+measurement of kinematic anisotropies with a network of Einstein Telescope and
+Cosmic Explorer will allow us to constrain the spectral shape with a precision
+of about 16$\%$. Finally, we identify cosmological and astrophysical scenarios
+where kinematic effects are enhanced in frequency ranges probed by current and
+future GW experiments.",2201.10464v2
+2022-02-06,Enhancing Perpendicular Magnetic Anisotropy in Garnet Ferrimagnet by Interfacing with Few-Layer WTe2,"Engineering magnetic anisotropy in a ferro- or ferrimagnetic (FM) thin film
+is crucial in spintronic device. One way to modify the magnetic anisotropy is
+through the surface of the FM thin film. Here, we report the emergence of a
+perpendicular magnetic anisotropy (PMA) induced by interfacial interactions in
+a heterostructure comprised of a garnet ferrimagnet, Y3Fe5O12 (YIG), and the
+low-symmetry, high spin orbit coupling (SOC) transition metal dichalcogenide,
+WTe2. At the same time, we also observed an enhancement in Gilbert damping in
+the WTe2 covered YIG area. Both the magnitude of interface-induced PMA and the
+Gilbert damping enhancement have no observable WTe2 thickness dependence down
+to single quadruple-layer, indicating that the interfacial interaction plays a
+critical role. The ability of WTe2 to enhance the PMA in FM thin film, combined
+with its previously reported capability to generate out-of-plane damping like
+spin torque, makes it desirable for magnetic memory applications.",2202.02834v1
+2022-03-09,Self-consistent dynamical models with a finite extent -- I. The uniform density sphere,"The standard method to generate dynamical models with a finite extent is to
+apply a truncation in binding energy to the distribution function. This
+approach has the disadvantages that one cannot choose the density to start
+with, that the important dynamical quantities cannot be calculated
+analytically, and that a fraction of the possible bound orbits are excluded a
+priori. We explore another route and start from a truncation in radius rather
+than a truncation in binding energy. We focus on the simplest truncated density
+profile, the uniform density sphere. We explore the most common inversion
+techniques to generate distribution functions for the uniform density sphere,
+corresponding to a large range of possible anisotropy profiles. We find that
+the uniform density sphere cannot be supported by the standard isotropic,
+constant anisotropy or Osipkov-Merritt models, as all these models are
+characterised by negative distribution functions. We generalise the Cuddeford
+inversion method to models with a tangential anisotropy and present a
+one-parameter family of dynamical models for the uniform density sphere. Each
+member of this family is characterised by an anisotropy profile that smoothly
+decreases from an arbitrary value $\beta_0\leqslant0$ at the centre to
+completely tangential at the outer radius. All models have a positive
+distribution function over the entire phase space, and a nonzero occupancy of
+all possible bound orbits. This shows that one can generate nontrivial
+self-consistent dynamical models based on preset density profile with a finite
+extent.",2203.04715v1
+2022-04-04,Angular dependence of the upper critical induction of clean $s$- and $d_{x^2-y^2}$-wave superconductors with self-consistent ellipsoidal effective mass and Zeeman anisotropies,"We employ the Schr{\""o}dinger-Dirac method generalized to an ellipsoidal
+effective mass anisotropy in order to treat the spin and orbital effective mass
+anisotropies self consistently, which is important when Pauli-limiting effects
+on the upper critical field characteristic of singlet superconductivity are
+present. By employing the Klemm-Clem transformations to map the equations of
+motion into isotropic form, we then calculate the upper critical magnetic
+induction $B_{c2}(\theta, \phi, T)$ at arbitrary directions and temperatures
+$T$ for isotropic $s$-wave and for anisotropic $d_{x^2-y^2}$-wave
+superconducting order parameters. As for anisotropic $s$-wave superconductors,
+the reduced upper critical field $b_{c2}$ is largest in the direction of the
+lowest effective mass, and is proportional to the universal orientation factor
+$\alpha(\theta,\phi)$. However, for $d_{x^2-y^2}$-wave pairing, ${\bm
+B}_{c2}(\pi/2,\phi,T)$ exhibits either a four-fold pattern with $C_4$ symmetry
+just below the transition temperature $T_c$ that rotates by $\pi/4$ as $T$ is
+lowered, or a two-fold pattern with $C_2$ symmetry, depending upon the planar
+effective mass anisotropy. This provides a new method to distinguish these
+pairing symmetries in clean unconventional superconductors.",2204.01246v1
+2022-04-14,Piezoelectric ferromagnetism in Janus monolayer YBrI: a first-principle prediction,"Coexistence of intrinsic ferromagnetism and piezoelectricity, namely
+piezoelectric ferromagnetism (PFM), is crucial to advance multifunctional
+spintronic technologies. In this work, we demonstrate that Janus monolayer YBrI
+is a PFM, which is dynamically, mechanically and thermally stable. Electronic
+correlation effects on physical properties of YBrI are investigated by using
+generalized gradient approximation plus $U$ (GGA+$U$) approach. For
+out-of-plane magnetic anisotropy, YBrI is a ferrovalley (FV) material, and the
+valley splitting is larger than 82 meV in considered $U$ range. The anomalous
+valley Hall effect (AVHE) can be achieved under an in-plane electric field.
+However, for in-plane magnetic anisotropy, YBrI is a common ferromagnetic (FM)
+semiconductor. When considering intrinsic magnetic anisotropy, the easy axis of
+YBrI is always in-plane with magnetic anisotropy energy (MAE) from 0.309 meV to
+0.237 meV ($U$=0.0 eV to 3.0 eV). However, the magnetization can be adjusted
+from the in-plane to off-plane direction by external magnetic field, and then
+lead to the occurrence of valley polarization. Moreover, missing centrosymmetry
+along with mirror symmetry breaking results in both in-plane and out-of-plane
+piezoelectricity in YBrI monolayer. At a typical $U$=2.0 eV, the $d_{11}$ is
+predicted to be -5.61 pm/V, which is higher than or compared with ones of other
+two-dimensional (2D) known materials. The electronic and piezoelectric
+properties of YBrI can be effectively tuned by applying a biaxial strain. For
+example, tensile strain can enhance valley splitting and $d_{11}$ (absolute
+value). The predicted Curie temperature of YBrI is higher than those of
+experimentally synthesized 2D ferromagnetic materials $\mathrm{CrI_3}$ and
+$\mathrm{Cr_2Ge_2Te_6}$.",2204.06713v1
+2022-05-04,Holographic Schwinger effect and electric instability with anisotropy,"According to the gauge-gravity duality, we systematically study the Schwinger
+effect and electric instability with anisotropy in a top-down holographic
+approach. The anisotropic black brane and bubble (soliton) background in IIB
+supergravity are employed and the dual theories in these backgrounds are
+expected to be anisotropic theory at finite temperature and anisotropic theory
+with confinement respectively. Then performing the potential analysis, we find
+due to the anisotropy, the potential barrier behaves oppositely with parallel
+and perpendicular electric fields, and this behavior agrees with the previous
+study about the quark potential with anisotropy in this system. Afterwards, we
+evaluate the pair production rate by solving the equation of motion for a
+fundamental string numerically which reveals the consistent behavior with the
+potential analysis. Furthermore, the probe D7-brane as flavor is introduced
+into the bulk in order to investigate the electric instability. The vacuum
+decay rate can be obtained by evaluating the imaginary part of the D7-brane
+action which again agrees with our potential analysis. Solving the associated
+constraint of gauge field strength on the flavor brane, we finally obtain the
+V-A curve displaying the distinct behavior of the conductivity in parallel and
+perpendicular direction which is in agreement with some bottom-up and
+phenomenologically holographic approaches in anisotropic fluid. Accordingly, we
+believe this work may be remarkable to study the electric features in strongly
+coupled anisotropic system.",2205.01885v3
+2022-05-31,Maximum likelihood kinetic Sunyaev Zel'dovich velocity reconstruction,"The kinetic Sunyaev Zel'dovich (kSZ) effect, cosmic microwave background
+(CMB) temperature anisotropies induced by the scattering of CMB photons from
+free electrons, will be measured by near-term CMB experiments at high
+significance. By combining CMB temperature anisotropies with a tracer of
+structure, such as a galaxy redshift survey, previous literature introduced a
+number of techniques to reconstruct the radial velocity field. This
+reconstructed radial velocity field encapsulates the majority of the
+cosmological information contained in the kSZ temperature anisotropies, and can
+provide powerful new tests of the standard cosmological model and theories
+beyond it. In this paper, we introduce a new estimator for the radial velocity
+field based on a coarse-grained maximum likelihood fit for the kSZ component of
+the temperature anisotropies, given a tracer of the optical depth. We
+demonstrate that this maximum likelihood estimator yields a higher fidelity
+reconstruction than existing quadratic estimators in the low-noise and
+high-resolution regime targeted by upcoming CMB experiments. We describe
+implementations of the maximum likelihood estimator in both harmonic space and
+map space, using either direct measurements of the optical depth field or a
+galaxy survey as a tracer. We comment briefly on the impact of biases
+introduced by imperfect reconstruction of the optical depth field.",2205.15779v1
+2022-06-29,Generalizing Monin-Obukhov similarity theory (1954) for complex atmospheric turbulence,"Monin-Obukhov similarity theory (MOST) stands at the center of understanding
+of atmospheric surface-layer turbulence. Based on the hypothesis that a single
+length scale determined by surface fluxes governs the turbulent exchange of
+momentum, mass, and energy between the Earth's surface and the atmosphere, MOST
+has been widely used in parametrizations of turbulent processes in virtually
+all numerical models of atmospheric flows. However, its inherent limitations to
+flat and horizontally homogeneous terrain, the non-scaling of horizontal
+velocity variances, and stable turbulence have plagued the theory since its
+inception. Thus, the limitations of MOST, and its use beyond its intended range
+of validity contribute to large uncertainty in weather, climate, and
+air-pollution models, particularly in polar regions and over complex terrain.
+Here we present a first generalized extension of MOST encompassing a wide range
+of realistic surface and flow conditions. The novel theory incorporates
+information on the directionality of turbulence exchange (anisotropy of the
+Reynolds stress tensor) as a key missing variable. The constants in the
+standard empirical MOST relations are shown to be functions of anisotropy, thus
+allowing a seamless transition between traditional MOST and its novel
+generalization. The new scaling relations, based on measurements from 13
+well-known datasets ranging from flat to highly complex mountainous terrain,
+show substantial improvements to scaling under all stratifications. The results
+also highlight the role of anisotropy in explaining general characteristics of
+complex terrain and stable turbulence, adding to the mounting evidence that
+anisotropy fully encodes the information on the complexity of the boundary
+conditions.",2206.14592v1
+2022-07-29,The role of magnetoelastic coupling and magnetic anisotropy in MnTiO$_3$,"We report the thermodynamic properties studied by thermal expansion,
+magnetostriction, magnetisation, and specific heat measurements as well as the
+low-energy magnetic excitations of \mto\ and investigate how magneto-elastic
+coupling and magnetic anisotropy affect the evolution of long-range order and
+the magnetic phase diagram. Specifically, we utilise high-resolution
+capacitance dilatometry and antiferromagnetic resonance (AFMR) studies by means
+of high-frequency electron spin resonance (HF-ESR) spectroscopy. The role of
+anisotropy is reflected by spin-reorientation at $B_{\rm{SF}}$~$\simeq 6$~T and
+a corresponding sign change in $\partial T_{\rm N}/\partial B$. Analysis of the
+AFMR modes enables us to establish the zero-field excitation gap $\Delta$ as
+well as its temperature dependence. We derive the effective anisotropy field
+$B_\mathrm{A} = 0.16(1)$~T which predominately originates from out-of-plane
+nearest-neighbour dipole-dipole interactions. Despite the nearly fully quenched
+orbital moment, our data show pronounced thermal expansion and magnetostriction
+anomalies at $T_{\rm N}$ and $B_{\rm{SF}}$ , respectively, which allows the
+experimental determination of sizable uniaxial pressure dependencies, i.e.,
+$\partial B_{\rm SF}/\partial p_{\rm c} = -0.20(2)$~T/GPa, $\partial T_{\rm N}/
+\partial p_b = 0.69(12)$~K/GPa, and $\partial T_{\rm N}/ \partial p_c =
+-2.0(4)$~K/GPa. Notably, short-range magnetic order appears up to at least
+3$T_{\rm N}$ , as indicated by anisotropic lattice distortion, the violation of
+a constant Gr\""uneisen behavior, and the presence of local magnetic fields
+detected by HF-ESR.",2207.14750v1
+2022-08-04,Anisotropic Magnetodielectric Coupling in Layered Antiferromagnetic FePS$_3$,"We report anisotropic magnetodielectric (MD) coupling in layered van der
+Waals (vdW) antiferromagnetic (AFM) FePS$_3$ (N\'eel temperature
+$T_{\mathrm{N}}$ $\sim$ 120K) with perpendicular anisotropy. Above $T_N$, while
+dielectric response function along \textit{c}-axis shows frequency dependent
+relaxations, in-plane data is frequency independent and reveals a deviation
+from phonon-anharmonicity in the ordered state, thereby implying a connection
+to spin-phonon coupling known to be indicative of onset of magnetic ordering.
+At low temperature (below 40 K), atypical anomaly in the dielectric constant is
+corroborated with temperature dependent DC and AC susceptibility. The
+magnetodielectric response across this anomaly differs significantly for both,
+in-plane and out-of-plane cases. We have explained this in terms of
+preferential orientation of magnetic AFM-z alignment, implied by the in-plane
+structural anisotropy as confirmed by \textit{ab-initio} calculations.
+Controlling relative strength of magnetodielectric coupling with magnetic
+anisotropy opens up a strategy for tracking subtle modifications of structure,
+such as in-plane anisotropy, with potential application to spintronic
+technologies.",2208.02729v2
+2022-08-07,Strain tunability of perpendicular magnetic anisotropy in van der Waals ferromagnets VI3,"Layered ferromagnets with high coercivity have special applications in
+nanoscale memory elements in electronic circuits, such as data storage.
+Therefore, searching for new hard ferromagnets and effectively tuning or
+enhancing the coercivity are the hottest topics in layered magnets today. Here,
+we report a strain tunability of perpendicular magnetic anisotropy in van der
+Waals (vdW) ferromagnets VI3 using magnetic circular dichroism measurements.
+For an unstrained flake, the M-H curve shows a rectangular-shaped hysteresis
+loop with perpendicular magnetic anisotropy and a large coercivity (up to 1.775
+T at 10 K). Furthermore, the coercivity can be enhanced to a maximum of 2.6 T
+at 10 K under a 2.9% in-plane tensile strain. Our DFT calculations show that
+the magnetic anisotropy energy (MAE) can be dramatically increased after
+applying an in-plain tensile strain, which contributes to the enhancement of
+coercivity in the VI3 flake. Meanwhile, the strain tunability on the coercivity
+of CrI3, with a similar crystal structure, is limited. The main reason is the
+strong spin-orbital coupling in V3+ in VI6 octahedra in comparison with that in
+Cr3+. The strain tunability of coercivity in VI3 flakes highlights its
+potential for integration into vdW heterostructures, paving the way toward
+nanoscale spintronic devices and applications in the future.",2208.03678v1
+2022-08-10,Enhancing the limit of uniaxial magnetic anisotropy induced by ion beam erosion,"The artificial tailoring of magnetic anisotropy by manipulation of
+interfacial morphology and film structure are of fundamental interest from
+application point of view in spintronic and magnetic memory devices. This
+letter reports an approach of engineering and enhancing the strength of oblique
+incidence ion beam erosion (IBE) induced in-plane uniaxial magnetic anisotropy
+(UMA) by simultaneous modification of film morphology as well as film texture.
+To meet this objective, Cobalt film and Si substrate have been taken as a model
+system. Unlike conventional post growth IBE of film, we direct our effort to
+the sequential deposition and subsequent IBE of the film. Detailed in-situ
+investigation insights that the film grows in highly biaxially textured
+polycrystalline state with formation of nanometric surface ripples. The film
+also exhibits pronounced UMA with easy axis oriented parallel to the surface
+ripple direction. Remarkably, the induced UMA is about one order of magnitude
+larger than the reported similar kind of earlier studies. The possibility of
+imposing in-plane crystallographic texture giving rise to magneto-crystalline
+anisotropy, along with long-range dipolar interaction throughout ripple crests
+enhances the strength of the UMA. The present findings can be further extended
+to systems characterized by different crystallographic structure and magnetic
+properties and show the general applicability of the present method.",2208.05249v1
+2022-08-23,Crystal anisotropy implications on the intrinsic magnetic and optical properties in van der Waals FePS3,"Antiferromagnetic (AFM) FePS3 has gained significant interest recently for
+its potential applications in spin-related devices. A single layer is comprised
+of a honeycomb network, stabilized by long-range spin-exchange interactions,
+with a zigzag or Neel arrangement of the Fe-atoms. This study exposed, for the
+first time, a strong impact of lateral crystal distortion on the magnetic
+arrangement and optical properties of FePS3. This impact was deciphered by
+correlating photoluminescence (PL) observations with single-crystal XRD which
+uncovered anisotropy in the a/b crystallographic plane. Thus, induceing a
+breakage in the inversion symmetry in FePS3 causing changes in it's electronic
+and optical transitions. The MPL observations exhibited an unexpected band-edge
+circularly polarized recombination emission, while off-band-edge transitions
+were linearly polarized. Also, temperature-dependent MPL measurements reflected
+zigzag-AFM at low temperatures and the coexistence of zigzag or Neel at mid
+temperatures. Theoretical calculation implementing anisotropy in spin-exchange
+interactions among Fe atom's nearest neighbors revealed stabilized zigzag
+arrangement tilted away from the a-axis. Furthermore, DFT calculations of the
+electronic band-edge predicted split states in degenerate symmetric points
+(K+/K-) for zigzag structure and non-degenerate for the Neel arrangement.
+Highlighting the importance of the inclusion of a crystallographic anisotropy
+parameter for the simulation of the experimental observations.",2208.10890v1
+2022-08-31,Detection of anisotropic satellite quenching in galaxy clusters up to $z\sim1$,"Satellite galaxies in the cluster environment are more likely to be quenched
+than galaxies in the general field. Recently, it has been reported that
+satellite galaxy quenching depends on the orientation relative to their central
+galaxies: satellites along the major axis of centrals are more likely to be
+quenched than those along the minor axis. In this paper, we report a detection
+of such anisotropic quenching up to $z\sim1$ based on a large
+optically-selected cluster catalogue constructed from the Hyper Suprime-Cam
+Subaru Strategic Program. We calculate the quiescent satellite galaxy fraction
+as a function of orientation angle measured from the major axis of central
+galaxies and find that the quiescent fractions at $0.25<z<1$ are reasonably
+fitted by sinusoidal functions with amplitudes of a few percent. Anisotropy is
+clearer in inner regions ($<r_\mathrm{200m}$) of clusters and not significant
+in cluster outskirts ($>r_\mathrm{200m}$). We also confirm that the observed
+anisotropy cannot be explained by differences in local galaxy density or
+stellar mass distribution along the two axes. Quiescent fraction excesses
+between the two axes suggest that the quenching efficiency contributing to the
+anisotropy is almost independent of stellar mass, at least down to our stellar
+mass limit of $M_{*}=1\times10^{10}\,M_{\odot}$. Finally, we argue that the
+physical origins of the observed anisotropy should have shorter quenching
+timescales than $\sim1\,\mathrm{Gyr}$, like ram-pressure stripping, because,
+for anisotropic quenching to be observed, satellites must be quenched before
+their initial orientation angles are significantly changed.",2209.00015v2
+2022-09-01,Comparing the counter-beaming and temperature anisotropy driven aperiodic electron firehose instabilities in collisionless plasma environments,"The electron firehose instabilities are among the most studied kinetic
+instabilities, especially in the context of space plasmas, whose dynamics is
+mainly controlled by collisionless wave-particle interactions. This paper
+undertakes a comparative analysis of the aperiodic electron firehose
+instabilities excited either by the anisotropic temperature or by the electron
+counter-beaming populations. Two symmetric counter-beams provide an effective
+kinetic anisotropy similar to the temperature anisotropy of a single
+(non-drifting) population, with temperature along the magnetic field direction
+larger than that in perpendicular direction. Therefore, the counter-beaming
+plasma is susceptible to firehose-like instabilities (FIs), parallel and
+oblique branches. Here we focus on the oblique beaming FI, which is also
+aperiodic when the free energy is provided by symmetric counter-beams. Our
+results show that, for relative small drifts or beaming speeds ($U$), not
+exceeding the thermal speed ($\alpha$), the aperiodic FIs exist in the same
+interval of wave-numbers and the same range of oblique angles (with respect to
+the magnetic field direction), but the growth rates of counter-beaming FI
+(CBFI) are always higher than those of temperature anisotropy FI (TAFI). For
+$U/\alpha > 1$, however, another electrostatic two-stream instability (ETSI) is
+also predicted, which may have growth rates higher than those of CBFI, and may
+dominate in that case the dynamics.",2209.00441v1
+2022-09-08,The Einasto model for dark matter haloes,"Context: The Einasto model has become one of the most popular models for
+describing the density profile of dark matter haloes. There have been
+relatively few comprehensive studies on the dynamical structure of the Einasto
+model, mainly because only a limited number of properties can be calculated
+analytically. Aims: We want to systematically investigate the photometric and
+dynamical structure of the family of Einasto models over the entire model
+parameter space. Methods: We used the SpheCow code to explore the properties of
+the Einasto model. We systematically investigated how the most important
+properties change as a function of the Einasto index $n$. We considered both
+isotropic models and radially anisotropic models with an Osipkov-Merritt
+orbital structure. Results: We find that all Einasto models with $n<\tfrac12$
+have a formal isotropic or Osipkov-Merritt distribution function that is
+negative in parts of phase space, and hence cannot be supported by such orbital
+structures. On the other hand, all models with larger values of $n$ can be
+supported by an isotropic orbital structure, or by an Osipkov-Merritt
+anisotropy, as long as the anisotropy radius is larger than a critical value.
+This critical anisotropy radius is a decreasing function of $n$, indicating
+that less centrally concentrated models allow for a larger degree of radial
+anisotropy. Conclusions: Studies of the structure and dynamics of models for
+galaxies and dark matter haloes should not be restricted to completely
+analytical models. Numerical codes such as SpheCow can help open up the range
+of models that are systematically investigated. This applies to the Einasto
+model discussed here, but also to other proposed models for dark matter haloes,
+including different extensions to the Einasto model.",2209.03639v1
+2022-09-14,Tuning magnetoelectricity in a mixed-anisotropy antiferromagnet,"Control of magnetization and electric polarization is attractive in relation
+to tailoring materials for data storage and devices such as sensors or
+antennae. In magnetoelectric materials, these degrees of freedom are closely
+coupled, allowing polarization to be controlled by a magnetic field, and
+magnetization by an electric field, but the magnitude of the effect remains a
+challenge in the case of single-phase magnetoelectrics for application. We
+demonstrate that the magnetoelectric properties of the mixed-anisotropy
+antiferromagnet LiNi$_{1-x}$Fe$_x$PO$_4$ are profoundly affected by replacing a
+fraction of the Ni$^{2+}$ ions with Fe$^{2+}$ on the transition metal site.
+This introduces random site-dependent single-ion anisotropy energies and causes
+a lowering of the magnetic symmetry of the system. In turn, magnetoelectric
+couplings that are symmetry-forbidden in the parent compounds, LiNiPO$_4$ and
+LiFePO$_4$, are unlocked and the dominant coupling is enhanced by two orders of
+magnitude. Our results demonstrate the potential of mixed-anisotropy magnets
+for tuning magnetoelectric properties.",2209.06702v1
+2022-09-22,"Single-crystal elastic moduli, anisotropy and the B1-B2 phase transition of NaCl at high pressures: Experiment vs. ab-initio calculations","Single-crystal elastic moduli, Cij, and the B1-B2 phase transition of NaCl
+were investigated experimentally, using time-domain Brillouin scattering
+(TDBS), and theoretically, via density-functional-theory (DFT), to 41 GPa.
+Thus, we largely extended pressure range where Cij and elastic anisotropy of
+the solid are measured, including the first experimental data for the
+high-pressure B2 phase, NaCl-B2. NaCl-B1 exhibits a strong and growing with
+pressure anisotropy, in contrast to NaCl-B2. Theoretical values obtained using
+different advanced DFT functionals were compared with our measurements but no
+one could satisfactorily reproduce our experimental data for NaCl-B1 and
+NaCl-B2 simultaneously. For all available DFT results on the principal shear
+moduli and anisotropy, the deviation became pronounced when the degree of
+compression increased significantly. Similar deviations could be also
+recognized for other cubic solids having the same B1-type structure and similar
+bonding, such as CaO, MgO, or (Mg1-x,Fex)O. Furthermore, the available
+experimental data suggest that the B1-B2 phase transition of NaCl and the above
+mentioned compounds are governed by the Born stability criterion C44(P) - P >
+0.",2209.10899v1
+2022-10-11,Magnetic anisotropy reversal driven by structural symmetry-breaking in monolayer α-RuCl3,"Layered {\alpha}-RuCl3 is a promising material to potentially realize the
+long-sought Kitaev quantum spin liquid with fractionalized excitations. While
+evidence of this exotic state has been reported under a modest in-plane
+magnetic field, such behavior is largely inconsistent with theoretical
+expectations of Kitaev phases emerging only in out-of-plane fields. These
+predicted field-induced states have been mostly out of reach due to the strong
+easy-plane anisotropy of bulk crystals, however. We use a combination of
+tunneling spectroscopy, magnetotransport, electron diffraction, and ab initio
+calculations to study the layer-dependent magnons, anisotropy, structure, and
+exchange coupling in atomically thin samples. Due to structural distortions,
+the sign of the average off-diagonal exchange changes in monolayer
+{\alpha}-RuCl3, leading to a reversal of magnetic anisotropy to easy-axis. Our
+work provides a new avenue to tune the magnetic interactions in {\alpha}-RuCl3
+and allows theoretically predicted quantum spin liquid phases for out-of-plane
+fields to be more experimentally accessible.",2210.05733v1
+2022-11-01,Observation of oscillating $g$-factor anisotropy arising from strong crystal lattice anisotropy in GaAs spin-3/2 hole quantum point contacts,"Many modern spin-based devices rely on the spin-orbit interaction, which is
+highly sensitive to the host semiconductor heterostructure and varies
+substantially depending on crystal direction, crystal asymmetry (Dresselhaus),
+and quantum confinement asymmetry (Rashba). One-dimensional quantum point
+contacts are a powerful tool to probe both energy and directional dependence of
+spin-orbit interaction through the effect on the hole $g$-factor. In this work
+we investigate the role of cubic crystal asymmetry in driving an oscillation in
+the in-plane hole $g$-factor anisotropy when the quantum point contact is
+rotated with respect to the crystal axes, and we are able to separate
+contributions to the Zeeman Hamiltonian arising from Rashba and cubic crystal
+asymmetry spin-orbit interactions. The in-plane $g$-factor is found to be
+extremely sensitive to the orientation of the quantum point contact, changing
+by a factor of $5$ when rotated by $45^{\circ}$. This exceptionally strong
+crystal lattice anisotropy of the in-plane Zeeman splitting cannot be explained
+within axially symmetric theoretical models. Theoretical modelling based on the
+combined Luttinger, Rashba and Dresselhaus Hamiltonians that we use here
+reveals new spin-orbit contributions to the in-plane hole $g$-factor and
+provides an excellent agreement with our experimental data.",2211.00253v2
+2022-12-03,Measurements of azimuthal anisotropy of nonprompt D$^0$ mesons in PbPb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV,"Measurements of the elliptic ($v_2$) and triangular ($v_3$) azimuthal
+anisotropy coefficients are presented for D$^0$ mesons produced in b hadron
+decays (nonprompt D$^0$ mesons) in lead-lead collisions at
+$\sqrt{s_\mathrm{NN}}$ = 5.02 TeV. The results are compared with previously
+published charm meson anisotropies measured using prompt D$^0$ mesons. The data
+were collected with the CMS detector in 2018 with an integrated luminosity of
+0.58 nb$^{-1}$. Azimuthal anisotropy is sensitive to the interactions of quarks
+with the hot and dense medium created in heavy ion collisions. Comparing
+results for prompt and nonprompt D$^0$ mesons can assist in understanding the
+mass dependence of these interactions. The nonprompt results show lower
+magnitudes of $v_2$ and $v_3$ and weaker dependences on the meson transverse
+momentum and collision centrality than those found for prompt D$^0$ mesons. The
+results are in agreement with theoretical predictions that include a mass
+dependence in the interactions of quarks with the medium.",2212.01636v2
+2022-12-12,Searching for anisotropic stochastic gravitational-wave backgrounds with constellations of space-based interferometers,"Many recent works have shown that the angular resolution of ground-based
+detectors is too poor to characterize the anisotropies of the stochastic
+gravitational-wave background (SGWB). For this reason, we asked ourselves if a
+constellation of space-based instruments could be more suitable. We consider
+the Laser Interferometer Space Antenna (LISA), a constellation of multiple
+LISA-like clusters, and the Deci-hertz Interferometer Gravitational-wave
+Observatory (DECIGO). Specifically, we test whether these detector
+constellations can probe the anisotropies of the SGWB. For this scope, we
+considered the SGWB produced by two astrophysical sources: merging compact
+binaries and a recently proposed scenario for massive black-hole seed formation
+through multiple mergers of stellar remnants. We find that measuring the
+angular power spectrum of the SGWB anisotropies is almost unattainable.
+However, it turns out that it could be possible to probe the SGWB anisotropies
+through cross-correlation with the CMB fluctuations. In particular, we find
+that a constellation of two LISA-like detectors and CMB-S4 can marginally
+constrain the cross-correlation between the CMB lensing convergence and the
+SGWB produced by the black hole seed formation process. Moreover, we find that
+DECIGO can probe the cross-correlation between the CMB lensing and the SGWB
+from merging compact binaries.",2212.06162v1
+2022-12-20,New universal property of cosmological gravitational wave anisotropies,"The anisotropies of the stochastic gravitational wave background, as produced
+in the early phases of cosmological evolution, can act as a key probe of the
+primordial universe particle content. We point out a new universal property of
+gravitational wave anisotropies of cosmological origin: for adiabatic initial
+conditions, their angular power spectrum is insensitive to the equation of
+state of the cosmic fluid driving the expansion before big-bang
+nucleosynthesis. Any deviation from this universal behaviour points to the
+presence of non-adiabatic sources of primordial fluctuations. Such scenarios
+can be tested by gravitational wave detectors operating at a frequency range
+which is fully complementary to CMB experiments. In this work we prove this
+general result, and we illustrate its consequences for a representative
+realisation of initial conditions based on the curvaton scenario. In the case
+of the simplest curvaton setup, we also find a significant cross-correlation
+between gravitational wave anisotropies and the CMB temperature fluctuations.
+There is a fourfold enhancement vis-\`{a}-vis the purely adiabatic scenario. We
+discuss the implications of our findings for identifying the origin of the
+(cosmological) gravitational wave background when, as is often the case, this
+cannot be determined solely on the basis of its spectral shape.",2212.10316v2
+2023-01-10,Compensation of anisotropy in spin-Hall devices for neuromorphic applications,"Spintronic nano-oscillators with reduced non-linearity could offer key
+benefits for realizing neuromorphic applications such as spike-based neurons
+and frequency multiplexing in neural networks. Here, we experimentally
+demonstrate the reduction in non-linearity of a spin-Hall nano-oscillator
+(SHNO) by compensation of its effective magnetic anisotropy. The study involves
+optimization of Co/Ni multilayer growth to achieve the compensation, followed
+by spin diode measurements on patterned microstrips to quantify their
+anisotropy. The relation between the second ($H_{k2}$ = 0.47 mT) and the first
+order ($H_{k1}^{eff}$ = $-$0.8 mT) anisotropy fields reveals the existence of
+an easy cone, thereby validating the presence of compensation. Furthermore, we
+demonstrate a synapse based on the compensated spin diode which has a fixed
+frequency when the input power is varied. We then study the current-induced
+auto-oscillation properties of SHNOs on compensated films by patterning
+nano-constrictions of widths 200 and 100 nm. The invariance of the resonance
+frequency and linewidth of the compensated SHNO with applied dc current
+indicates the absence of non-linearity. This independence is maintained
+irrespective of the applied external fields and its orientations. The
+compensated SHNO obtained has a linewidth of 1.1 MHz and a peak output power of
+up to 1 pW/MHz emulating a nano-neuron with a low linewidth and a fixed
+frequency.",2301.03794v1
+2023-01-10,Magnetic anisotropy and low-energy spin dynamics in the van der Waals compounds Mn$_{2}$P$_{2}$S$_{6}$ and MnNiP$_{2}$S$_{6}$,"We report the detailed high-field and high-frequency electron spin resonance
+(HF-ESR) spectroscopic study of the single-crystalline van der Waals compounds
+Mn$_{2}$P$_{2}$S$_{6}$ and MnNiP$_{2}$S$_{6}$. Analysis of magnetic excitations
+shows that in comparison to Mn$_{2}$P$_{2}$S$_{6}$ increasing the Ni content
+yields a larger magnon gap in the ordered state and a larger g-factor value and
+its anisotropy in the paramagnetic state. The studied compounds are found to be
+strongly anisotropic having each the unique ground state and type of magnetic
+order. Stronger deviation of the g-factor from the free electron value in the
+samples containing Ni suggests that the anisotropy of the exchange is an
+important contributor to the stabilization of a certain type of magnetic order
+with particular anisotropy. At temperatures above the magnetic order, we have
+analyzed the spin-spin correlations resulting in a development of slowly
+fluctuating short-range order. They are much stronger pronounced in
+MnNiP$_{2}$S$_{6}$ compared to Mn$_{2}$P$_{2}$S$_{6}$. The enhanced spin
+fluctuations in MnNiP$_{2}$S$_{6}$ are attributed to the competition of
+different types of magnetic order. Finally, the analysis of the temperature
+dependent critical behavior of the magnon gaps below the ordering temperature
+in Mn$_{2}$P$_{2}$S$_{6}$ suggests that the character of the spin wave
+excitations in this compound undergoes a field induced crossover from a 3D-like
+towards 2D XY regime.",2301.04239v2
+2023-01-11,Traveling wave enantio-selective electron paramagnetic resonance,"We propose a novel method for enantio-selective electron paramagnetic
+resonance spectroscopy based on magneto-chiral anisotropy. We calculate the
+strength of this effect and propose a dedicated interferometer setup for its
+observation.",2301.04755v1
+2023-02-15,"A ""morphogenetic action"" principle for 3D shape formation by the growth of thin sheets","How does growth encode form in developing organisms? Many different
+spatiotemporal growth profiles may sculpt tissues into the same target 3D
+shapes, but only specific growth patterns are observed in animal and plant
+development. In particular, growth profiles may differ in their degree of
+spatial variation and growth anisotropy, however, the criteria that distinguish
+observed patterns of growth from other possible alternatives are not
+understood. Here we exploit the mathematical formalism of quasiconformal
+transformations to formulate the problem of ""growth pattern selection""
+quantitatively in the context of 3D shape formation by growing 2D epithelial
+sheets. We propose that nature settles on growth patterns that are the
+'simplest' in a certain way. Specifically, we demonstrate that growth pattern
+selection can be formulated as an optimization problem and solved for the
+trajectories that minimize spatiotemporal variation in areal growth rates and
+deformation anisotropy. The result is a complete prediction for the growth of
+the surface, including not only a set of intermediate shapes, but also a
+prediction for cell displacement along those surfaces in the process of growth.
+Optimization of growth trajectories for both idealized surfaces and those
+observed in nature show that relative growth rates can be uniformized at the
+cost of introducing anisotropy. Minimizing the variation of programmed growth
+rates can therefore be viewed as a generic mechanism for growth pattern
+selection and may help to understand the prevalence of anisotropy in
+developmental programs.",2302.07839v1
+2023-03-12,Investigating the elliptic anisotropy of identified particles in p--Pb collisions with a multi-phase transport model,"The elliptic azimuthal anisotropy coefficient ($v_{2}$) of the identified
+particles at midrapidity ($|\eta|<0.8$) was investigated in p--Pb collisions at
+$\sqrt{s_\mathrm{NN}}=$ 5.02 TeV using a multi-phase transport model (AMPT).
+The calculations of differential $v_{2}$ based on the advanced flow extraction
+method of light flavor hadrons (pions, kaons, protons, and $\Lambda$) in small
+collision systems were extended to a wider transverse momentum
+($p_{\mathrm{T}}$) range of up to 8 GeV/$c$ for the first time. The
+string-melting version of the AMPT model provides a good description of the
+measured $p_{\mathrm{T}}$-differential $v_{2}$ of the mesons but exhibits a
+slight deviation from the baryon $v_{2}$. In addition, we observed the features
+of mass ordering at low $p_{\mathrm{T}}$ and the approximate number of
+constituent quarks (NCQ) scaled at intermediate $p_{\mathrm{T}}$. Moreover, we
+demonstrate that hadronic rescattering does not have a significant impact on
+$v_{2}$ in p--Pb collisions for different centrality selections, whereas
+partonic scattering dominates in generating the elliptic anisotropy of the
+final particles. This study provides further insight into the origin of
+collective-like behavior in small collision systems and has referential value
+for future measurements of azimuthal anisotropy.",2303.06577v3
+2023-03-16,Measuring galaxy cluster mass profiles into the low acceleration regime with galaxy kinematics,"We probe the dynamical mass profiles of 10 galaxy clusters from the HIghest
+X-ray FLUx Galaxy Cluster Sample (HIFLUGCS) using galaxy kinematics. We
+numerically solve the spherical Jeans equation, and parameterize the dynamical
+mass profile and the galaxy velocity anisotropy profile using two general
+functions to ensure that our results are not biased towards any specific model.
+The mass-velocity anisotropy degeneracy is ameliorated by using two ""virial
+shape parameters"" that depend on the fourth moment of velocity distribution.
+The resulting velocity anisotropy estimates consistently show a nearly
+isotropic distribution in the inner regions, with an increasing radial
+anisotropy towards large radii. We compare our derived dynamical masses with
+those calculated from X-ray gas data assuming hydrostatic equilibrium, finding
+that massive and rich relaxed clusters generally present consistent mass
+measurements, while unrelaxed or low-richness clusters have systematically
+larger total mass than hydrostatic mass by an average of 50\%. This might help
+alleviate current tensions in the measurement of $\sigma_8$, but it also leads
+to cluster baryon fractions below the cosmic value. Finally, our approach
+probes accelerations as low as $10^{-11}$ m s$^{-2}$, comparable to the
+outskirts of individual late-type galaxies. We confirm that galaxy clusters
+deviate from the radial acceleration relation defined by galaxies.",2303.10175v2
+2023-03-20,Scaling anisotropy with stationary background field in the near-Sun solar wind turbulence,"The scaling of magnetic fluctuations provides crucial information for the
+understanding of solar wind turbulence. However, the observed magnetic
+fluctuations contain not only turbulence but also magnetic structures, leading
+to the violation of the time stationarity. This violation would conceal the
+true scaling and influence the determination of the sampling angle with respect
+to the local background magnetic field. Here, to investigate the scaling
+anisotropy, we utilize an easy but effective criterion $\phi<10^\circ$ to
+ensure the time stationarity of the magnetic field, where $\phi$ is the angle
+between the two averaged magnetic fields after cutting the interval into two
+halves. We study the scaling anisotropy using higher-order statistics of
+structure functions under the condition of stationarity for the near-Sun solar
+wind turbulence for the first time based on measurements obtained from Parker
+Solar Probe (PSP) at 0.17 au. We find that the scaling indices $\xi$ of
+magnetic field show a linear dependence on the order $p$ close to $\xi(p)=p/4$.
+The multifractal scaling of magnetic-trace structure functions becomes
+monoscaling close to $\xi(p)=p/3$ with the local magnetic field perpendicular
+to the sampling direction and close to $\xi(p)=p/4$ with the local magnetic
+field parallel to the sampling direction when measured with the stationary
+background magnetic field. The scaling of velocity-trace structure functions
+has similar but less significant changes. The near-Sun solar wind turbulence
+displays different scaling anisotropies with the near-Earth solar wind
+turbulence, suggesting the evolution of the nonlinear interaction process
+during the solar wind expansion.",2303.10810v1
+2023-03-20,Violation of Emergent Rotational Symmetry in the Hexagonal Kagome Superconductor CsV3Sb5,"Superconductivity is caused by electron pairs that are canonically isotropic,
+whereas some exotic superconductors are known to exhibit non-trivial anisotropy
+stemming from unconventional pairings. However, superconductors with hexagonal
+symmetry, the highest rotational symmetry allowed in crystals, exceptionally
+have strong constraint that is called emergent rotational symmetry (ERS):
+anisotropic properties should be very weak especially near the critical
+temperature Tc even for unconventional pairings such as d-wave states. Here, we
+investigate superconducting anisotropy of the recently-found hexagonal Kagome
+superconductor CsV3Sb5, which is known to exhibit various intriguing phenomena
+originating from its undistorted Kagome lattice formed by vanadium atoms. Based
+on calorimetry performed under accurate two-axis field-direction control, we
+discover a combination of six- and two-fold anisotropies in the in-plane upper
+critical field. Both anisotropies, robust up to very close to Tc, are beyond
+predictions of standard theories. We infer that this clear ERS violation with
+nematicity is best explained by multi-component nematic superconducting order
+parameter in CsV3Sb5 intertwined with symmetry breakings caused by the
+underlying charge-density-wave order.",2303.11072v1
+2023-03-27,Strain effects on magnetic compensation and spin reorientation transition of Co/Gd synthetic ferrimagnets,"Synthetic ferrimagnets are an attractive materials class for spintronics as
+they provide access to all-optical switching of magnetization and, at the same
+time, allow for ultrafast domain wall motion at angular momentum compensation.
+In this work, we systematically study the effects of strain on the
+perpendicular magnetic anisotropy and magnetization compensation of Co/Gd and
+Co/Gd/Co/Gd synthetic ferrimagnets. Firstly, the spin reorientation transition
+of a bilayer system is investigated in wedge type samples, where we report an
+increase in the perpendicular magnetic anisotropy in the presence of in-plane
+strain. Using a model for magnetostatics and spin reorientation transition in
+this type of system, we confirm that the observed changes in anisotropy field
+are mainly due to the Co magnetoelastic anisotropy. Secondly, the magnetization
+compensation of a quadlayer is studied. We find that magnetization compensation
+of this synthetic ferrimagnetic system is not altered by external strain. This
+confirms the resilience of this material system against strain that may be
+induced during the integration process, making Co/Gd ferrimagnets suitable
+candidates for spintronics applications.",2303.15191v4
+2023-03-28,L1$_0$ FePt thin films with tilted and in-plane magnetic anisotropy: first-principles study,"Ultrathin L1$_0$ films with different $c$-axis orientations relative to the
+film plane are promising candidates for data storage materials. In this work,
+within the framework of density functional theory, we calculated the magnetic
+properties of ultrathin L1$_0$ (111) and (010) films with thicknesses ranging
+from 4 to 16 atomic monolayers (from about 0.8 to 3.5~nm). The highest average
+magnetic moments are observed for the thinnest films considered, and with
+increasing film thickness, the values converge towards the magnetic moment for
+bulk. The observed increase comes mainly from enhanced moments in the two
+atomic monolayers closest to the surface of the films. The easy axis of
+magnetization of (111) films prefers an alignment close to the tetragonal axis,
+an example of tilted magnetic anisotropy. The 6-monolayer (111) film (about
+1.3~nm thick) inclines the easy axis of magnetization of about 45{\deg} to the
+film plane, which can find use in applications. The (010) films show an
+in-plane easy magnetization axis in a unique L1$_0$ tetragonal direction. This
+is an unusual type of in-plane anisotropy, as the particular direction
+preference is very strong. The computational results encourage further
+experimental studies of L1$_0$ systems with tilted and in-plane fixed magnetic
+anisotropy.",2303.15877v2
+2023-04-05,Unstable Anisotropic Neutron Stars: Probing the Limits of Gravitational Collapse,"The aim of this paper is to investigate the effects of anisotropy on the
+gravitational collapse of unstable neutron stars. We utilize the BL-Model to
+describe the anisotropy inside the neutron star and construct a family of
+anisotropic neutron stars for BSk21-EOS. We subject these stars to radial
+perturbations to study their stability against radial oscillations, and analyze
+the effects of anisotropy on the large frequency separation for systems with
+and without crust. To observe the unstable branch in the respective profile
+curves, we calculate the properties of anisotropic neutron stars in advance. We
+compare the obtained radial stability curve to the standard criterion for
+radial stability ($\frac{\partial M}{\partial \rho_c } > 0 $) and find that the
+stability limit of anisotropic stars is more accurately described by the radial
+stability curve. We filter out all sequence of anisotropic neutron stars that
+exceed the stability limit obtained from the radial stability curve. The
+ultimate fate of these unstable anisotropic neutron stars is to collapse into a
+black hole. To study the dynamical evolution of such unstable anisotropic
+neutron stars, we consider a non-ideal fluid in a non-adiabatic background. We
+examine the time-evolution of key properties such as mass, density, heat flux,
+and anisotropy during the process of gravitational collapse. To better
+visualize this process, we perform a contour simulation (Fig.
+\ref{fig:ns-params_time_evolution}). Finally, we introduce a few challenging
+yet plausible mechanisms for detecting such high-energy gravitational collapse
+events.",2304.02439v2
+2023-04-13,Element-Specific Study of Magnetic Anisotropy and Hardening in SmCo$_{5-x}$Cu$_{x}$ Thin Films,"This work investigates the effect of copper substitution on the magnetic
+properties of SmCo$_{5}$ thin films synthesized by molecular beam epitaxy. A
+series of thin films with varying concentrations of Cu were grown under
+otherwise identical conditions to disentangle structural and compositional
+effects on the magnetic behavior. The combined experimental and theoretical
+studies show that Cu substitution at the Co$_{3g}$ sites not only stabilizes
+the formation of the SmCo$_{5}$ structure but enhances magnetic anisotropy and
+coercivity. Density functional theory calculations indicate that
+Sm(Co$_4$Cu$_{3g}$)$_5$ possesses a higher single-ion anisotropy as compared to
+pure SmCo$_{5}$. In addition, X-ray magnetic circular dichroism reveals that Cu
+substitution causes an increasing decoupling of the Sm 4\textit{f} and Co
+3\textit{d} moments. Scanning transmission electron microscopy confirms
+predominantly SmCo$_{5}$ phase formation and reveals nanoscale inhomogeneities
+in the Cu and Co distribution. Our study based on thin film model systems and
+advanced characterization as well as modeling reveals novel aspects of the
+complex interplay of intrinsic and extrinsic contributions to magnetic
+hysteresis in rare earth-based magnets, \textit{i.e.} the combination of
+increased intrinsic anisotropy due to Cu substitution and the extrinsic effect
+of inhomogeneous elemental distribution of Cu and Co.",2304.06457v1
+2023-05-01,Perpendicular magnetic anisotropy of an ultrathin Fe layer grown on NiO(001),"The magnetic anisotropy and magnetic interactions at the interface between Fe
+and NiO(001) were investigated. Depending on the growth conditions of the
+NiO(001) layers and the post-annealing temperature, the preferential
+magnetization direction of the ultrathin Fe layer grown on a NiO(001) layer
+changed from in-plane to a direction perpendicular to the film plane. The
+lattice constant of the NiO(001) layers parallel to the growth direction
+increased with O$_2$ flow rate, while that parallel to the in-plane were locked
+onto the MgO(001) substrate regardless of the growth conditions of the NiO
+layers. Moreover, perpendicular magnetization was observed only when the NiO
+layer was grown with O$_2$ flow rates higher than 2.0 sccm corresponding to
+oxygen-rich NiO. X-ray magnetic circular dichroism measurements revealed an
+enhancement in anisotropic orbital magnetic moments similar to the origin of
+perpendicular magnetic anisotropy at the Fe/MgO(001) interface. The interfacial
+magnetic anisotropy energies were 0.93 and 1.02 mJ/m$^2$ at room temperature
+and at 100 K, respectively, indicating less temperature dependence. In
+contrast, the coercivity $H_c$ exhibited a significant temperature dependence.
+Although no signature of exchange bias or unidirectional loop shift was
+observed, $H_c$ was strongly dependent on the NiO layer thickness, indicating
+that the exchange interaction at the interface between the ferromagnetic and
+antiferromagnetic layers was not negligible, despite the NiO(001) being a
+spin-compensated surface.",2305.00672v1
+2023-05-15,The influence of anisotropy on the manifestation of aging effects in the magnetoresistance of multilayer structures,"Currently, aging effects occurring in multilayer systems attract much
+attention from researchers. In our research we looked at the behavior of
+multilayer systems that depend on anisotropy, magnetoresistance and
+susceptibility.All these parameters are interrelated and have varying degrees
+of influence on the effects of aging. We researched our Co-layers magnetic
+system from high-temperature and low-temperature initial states, as well as not
+only in the critical temperature region, but in a wide low-temperature range.
+The study was carried out with different types of magnetic anisotropy, which
+made it possible to identify differences in the behavior of the system
+depending on the type of anisotropy. We found that in systems exhibiting a
+dimensional transition, aging effects manifest to gain and themselves in a wide
+low-temperature range, and not only in a narrow near-critical region, which
+ultimately leads us to a wide range of applications of these materials for
+practical applications.",2305.08656v4
+2023-06-01,"Diffuse Sources, Clustering and the Excess Anisotropy of the Radio Synchrotron Background","We present the largest low frequency (120~MHz) arcminute resolution image of
+the radio synchrotron background (RSB) to date, and its corresponding angular
+power spectrum of anisotropies (APS) with angular scales ranging from $3^\circ$
+to $0.3^\prime$. We show that the RSB around the North Celestial Pole has a
+significant excess anisotropy power at all scales over a model of unclustered
+point sources based on source counts of known source classes. This anisotropy
+excess, which does not seem attributable to the diffuse Galactic emission,
+could be linked to the surface brightness excess of the RSB. To better
+understand the information contained within the measured APS, we model the RSB
+varying the brightness distribution, size, and angular clustering of potential
+sources. We show that the observed APS could be produced by a population of
+faint clustered point sources only if the clustering is extreme and the size of
+the Gaussian clusters is $\lesssim 1'$. We also show that the observed APS
+could be produced by a population of faint diffuse sources with sizes $\lesssim
+1'$, and this is supported by features present in our image. Both of these
+cases would also cause an associated surface brightness excess. These classes
+of sources are in a parameter space not well probed by even the deepest radio
+surveys to date.",2306.00829v1
+2023-06-10,The Central Role of Tilted Anisotropy for Field-Free Spin-Orbit Torque Switching of Perpendicular Magnetization,"The discovery of efficient magnetization switching activated by the spin Hall
+effect (SHE)-induced spin-orbit torque (SOT) changed the course of magnetic
+random-access memory (MRAM) research and development. However, for systems with
+perpendicular magnetic anisotropy (PMA), the use of SOT is still hampered by
+the necessity of a longitudinal magnetic field to break the magnetic symmetry
+to achieve deterministic switching. In this work, we first demonstrate that a
+robust and tunable field-free current-driven SOT switching of perpendicular
+magnetization can be controlled by the growth protocol in Pt-based magnetic
+heterostructures. It is further elucidated that such growth-dependent symmetry
+breaking is originated from the laterally tilted magnetic anisotropy of the
+ferromagnetic layer with PMA, which has been largely neglected in previous
+studies and its critical role should be re-focused. We show by both experiments
+and simulations that in a PMA system with tilted anisotropy, the deterministic
+field-free switching possesses a conventional SHE-induced damping-like torque
+feature and the resulting current-induced effective field has a non-linear
+dependence on the applied current density, which could be potentially
+misattributed to an unconventional SOT origin.",2306.06357v1
+2023-06-20,Magnetic Exciton-Polariton with Strongly Coupled Atomic and Photonic Anisotropies,"Anisotropy plays a key role in science and engineering. However, the
+interplay between the material and engineered photonic anisotropies has hardly
+been explored due to the vastly different length scales. Here we demonstrate a
+matter-light hybrid system, exciton-polaritons in a 2D antiferromagnet, CrSBr,
+coupled with an anisotropic photonic crystal (PC) cavity, where the spin,
+atomic lattice, and photonic lattices anisotropies are strongly correlated,
+giving rise to unusual properties of the hybrid system and new possibilities of
+tuning. We show exceptionally strong coupling between engineered anisotropic
+optical modes and anisotropic excitons in CrSBr, which is stable against
+excitation densities a few orders of magnitude higher than polaritons in
+isotropic materials. Moreover, the polaritons feature a highly anisotropic
+polarization tunable by tens of degrees by controlling the matter-light
+coupling via, for instance, spatial alignment between the material and photonic
+lattices, magnetic field, temperature, cavity detuning and cavity
+quality-factors. The demonstrated system provides a prototype where atomic- and
+photonic-scale orders strongly couple, opening opportunities of photonic
+engineering of quantum materials and novel photonic devices, such as compact,
+on-chip polarized light source and polariton laser.",2306.11265v2
+2023-06-26,Detecting anisotropies of the stochastic gravitational wave background with TianQin,"The investigation of the anisotropy of the stochastic gravitational wave
+background (SGWB) using the TianQin detector plays a crucial role in studying
+the early universe and astrophysics. In this work, we examine the response of
+the $AET$ channel of the TianQin Time Delay Interferometry (TDI) to the
+anisotropy of the SGWB. We calculate the corresponding angular sensitivity
+curves and find that TianQin is capable of detecting the anisotropy of the
+SGWB, with an angular sensitivity reaching $10^{-10}$ for quadrupoles. Due to
+the fixed $z$-axis of TianQin pointing towards J0806, its overlap reduction
+functions (ORFs) exhibit specific symmetries, enabling the resolution of
+different multipole moments $\ell m$. The detection sensitivity is optimal for
+the $(2, 0)$ mode, with a sensitivity reaching $10^{-10}$. Using the Fisher
+matrix approach, we estimate the parameters and find that in the power-law
+spectrum model, higher logarithmic amplitudes lead to more effective
+reconstruction of the spectral index for all multipole moments. Under the
+optimal scenario with a signal amplitude of $\Omega_{\mathrm{GW}} (f =
+f_{\mathrm{c}}) h^2 = 10^{-9}$, the spectral indices can be reconstructed with
+uncertainties of $10^{-3}$, $10$, and $10^{-3}$ for $\ell = 0$, $1$, and $2$
+multipole moments, respectively. For the cases of $(\ell, m) = (0, 0)$, $(1,
+1)$, $(2, 0)$, and $(2, 2)$, the spectral indices can be reconstructed with
+uncertainties of $10^{-3}$, $10$, $10^{-3}$, and $10$, respectively.",2306.14439v3
+2023-07-22,Magnetization dynamics due to field interplay in field free spin Hall nano-oscillators,"Spin Hall nano oscillators (SHNOs) have shown applications in unconventional
+computing schemes and broadband frequency generation in the presence of applied
+external magnetic field. However, under field-free conditions, the oscillation
+characteristics of SHNOs display a significant dependence on the effective
+field, which can be tuned by adjusting the constriction width, thereby
+presenting an intriguing area of study. Here we study the effect of nano
+constriction width on the magnetization dynamics in anisotropy assisted field
+free SHNOs. In uniaxial anisotropy-based field-free SHNOs, either the
+anisotropy field or the demagnetization field can dominate the magnetization
+dynamics depending on the constriction width. Our findings reveal distinct
+auto-oscillation characteristics in narrower constrictions with 20 nm and 30 nm
+constriction width compared to their wider counterpart with 100 nm width. The
+observed frequency shift variations with input current and constriction widths
+stem from the inherent nonlinearity of the system. The interplay between the
+B_demag and B_anis, coupled with changes in constriction width, yields rich
+dynamics and offers control over frequency tunability, auto oscillation
+amplitude, and threshold current. Notably, the spatial configuration of spin
+wave wells within the constriction undergoes transformations in response to
+changes in both constriction width and anisotropy. The findings highlight the
+significant influence of competing fields at the constriction on the field-free
+auto oscillations of SHNOs, with this impact intensifying as the constriction
+width is varied.",2307.12068v1
+2023-09-18,Phase transitions in the anisotropic XY ferromagnet with quenched nonmagnetic impurity,"The three dimensional anisotropic XY ferromagnet has been studied by Monte
+Carlo simulation. The ferro-para phase transition has been observed to take
+place at a lower temperature for impure anisotropic XY ferromagnet. The
+pseudocritical temperature ($T_c^*$) has been found to decrease as the system
+gets more and more impure (impurity concentration $p$ increases). In the case
+of bilinear exchange type of anisotropy ($\lambda$), the pseudocritical
+temperature ($T_c^*$) increases linearly with $\lambda$ for any given
+concentration of nonmagnetic impurity ($p$). The slope of this linear function
+has been found to depend on the impurity concentration ($p$). The slope
+decreases linearly with the impurity concentration ($p$). In the case of the
+single site anisotropy ($D$), the pseudocritical temperature ($T_c^*$) has been
+found to decrease linearly with $p$ for fixed $D$. The critical temperature
+(for a fixed set of parameter values) has been estimated from the temperature
+variation of fourth order Binder cumulants ($U_L$) for different system sizes
+($L$). The critical magnetisation ($M(T_c)$) and the maximum value of the
+susceptibility ($\chi_p$) are calculated for different system sizes ($L$). The
+critical exponents for the assumed scaling laws, $M(T_c) \sim L^{-{{\beta}
+\over {\nu}}}$ and $\chi_p \sim L^{{{\gamma} \over {\nu}}}$, are estimated
+through the finite size analysis. We have estimated, ${{\beta} \over {\nu}}$,
+equals to $0.48\pm0.05$ and $0.37\pm0.04$ for bilinear exchange and single site
+anisotropy respectively. We have also estimated, ${{\gamma} \over {\nu}}$
+equals to $1.78\pm0.05$ and $1.81\pm0.05$ for bilinear exchange and single site
+anisotropy respectively.",2309.09659v3
+2023-10-05,Study of azimuthal anisotropy of $Υ$(1S) mesons in pPb collisions at $\sqrt{s_\mathrm{NN}}$ = 8.16 TeV,"The azimuthal anisotropy of $\Upsilon$(1S) mesons in high-multiplicity
+proton-lead collisions is studied using data collected by the CMS experiment at
+a nucleon-nucleon center-of-mass energy of 8.16 TeV. The $\Upsilon$(1S) mesons
+are reconstructed using their dimuon decay channel. The anisotropy is
+characterized by the second Fourier harmonic coefficients, found using a
+two-particle correlation technique, in which the $\Upsilon$(1S) mesons are
+correlated with charged hadrons. A large pseudorapidity gap is used to suppress
+short-range correlations. Nonflow contamination from the dijet background is
+removed using a low-multiplicity subtraction method, and the results are
+presented as a function of $\Upsilon$(1S) transverse momentum. The azimuthal
+anisotropies are smaller than those found for charmonia in proton-lead
+collisions at the same collision energy, but are consistent with values found
+for $\Upsilon$(1S) mesons in lead-lead interactions at a nucleon-nucleon
+center-of-mass energy of 5.02 TeV.",2310.03233v2
+2023-08-29,Multiscale and Anisotropic Characterization of Images Based on Complexity: an Application to Turbulence,"This article presents a multiscale, non-linear and directional statistical
+characterization of images based on the estimation of the skewness, flatness,
+entropy and distance from Gaussianity of the spatial increments. These
+increments are characterized by their magnitude and direction; they allow us to
+characterize the multiscale properties directionally and to explore anisotropy.
+To describe the evolution of the probability density function of the increments
+with their magnitude and direction, we use the skewness to probe the symmetry,
+the entropy to measure the complexity, and both the flatness and distance from
+Gaussianity to describe the shape. These four quantities allow us to explore
+the anisotropy of the linear correlations and non-linear dependencies of the
+field across scales. First, we validate the methodology on two-dimensional
+synthetic scale-invariant fields with different multiscale properties and
+anisotropic characteristics. Then, we apply it on two synthetic turbulent
+velocity fields: a perfectly isotropic and homogeneous one, and a channel flow
+where boundaries induce inhomogeneity and anisotropy. Our characterization
+unambiguously detects the anisotropy in the second case, where our quantities
+report scaling properties that depend on the direction of analysis.
+Furthermore, we show in both cases that turbulent velocity fluctuations are
+always isotropic, when the mean velocity profile is adequately removed.",2310.05946v1
+2023-10-24,In memoriam Pal Revesz(1934-2022) The random walk from orthogonality to anisotropy,"A tribute to the life and work of Pal Revesz. The Hungarian mathematical
+community lost one of his leading members, when Pal Revesz passed away on 14 of
+November 2022.",2310.16163v1
+2023-11-07,Spectral scaling of unstably-stratified atmospheric flows: understanding the low frequency spread of Kaimal model,"For more than five decades, a notable spread in the low frequencies of
+velocity and temperature spectra, scaled using inertial subrange properties and
+Monin-Obukhov similarity theory, has been observed in unstable stratification.
+A large ensemble of 14 datasets, over relatively simple terrain (from flat and
+homogeneous to gentle slope or valley floor) and very complex terrain (steep
+slope, crater rim, mountain top), are used to assess the reasons of this
+low-frequency behaviour.
+  Turbulence anisotropy is shown to be the primary factor influencing the
+spectral energy at the largest scales and the spectral peak position of
+streamwise and spanwise velocity spectra, with stability acting as a secondary
+factor. On the contrary, the low-frequency behaviour of surface-normal and
+temperature spectra is dominated by stability effects, while turbulence
+anisotropy plays a secondary role. These observations are valid over both
+simple and complex terrain, even though variability of the largest scales of
+complex terrain datasets integrate other processes not included in turbulence
+anisotropy or stability conditions.
+  Using a combination of non-dimensional turbulence parameters - temperature
+and velocity variances as well as dissipation of turbulence kinetic energy and
+of temperature variance - and of a semi-empirical model provided in the
+literature, we are able to describe the behaviour of the velocity and
+temperature spectra with only turbulence anisotropy and stability as input
+parameters.
+  Finally, the paper provides some insights into the nature of anisotropic
+eddies, as well as the relationship between the boundary layer height and the
+spectral behaviour.",2311.03859v1
+2023-11-15,Merger Response of Halo Anisotropy Properties,"Anisotropy properties -- halo spin, shape, position offset, velocity offset,
+and orientation -- are an important family of dark matter halo properties that
+indicate the level of directional variation of the internal structures of
+haloes. These properties reflect the dynamical state of haloes, which in turn
+depends on the mass assembly history. In this work, we study the evolution of
+anisotropy properties in response to merger activity using the IllustrisTNG
+simulations. We find that the response trajectories of the anisotropy
+properties significantly deviate from secular evolution. These trajectories
+have the same qualitative features and timescales across a wide range of merger
+and host properties. We propose explanations for the behaviour of these
+properties and connect their evolution to the relevant stages of merger
+dynamics. We measure the relevant dynamical timescales. We also explore the
+dependence of the strength of the response on time of merger, merger ratio, and
+mass of the main halo. These results provide insight into the physics of halo
+mergers and their effects on the statistical behaviour of halo properties. This
+study paves the way towards a physical understanding of scaling relations,
+particularly to how systematics in their scatter are connected to the mass
+assembly histories of haloes.",2311.08664v1
+2023-12-07,Features of magnetization and spin reorientation in weak ferrimagnets of the YFe$_{1-x}$Cr$_x$O$_3$ type,"A brief critical review is given of the 50-year history of experimental and
+theoretical studies of the magnetic properties of a new promising class of weak
+ferrimagnets such as RFe$_{1-x}$Cr$_x$O$_3$ with a non-magnetic R-ion (R = La ,
+Y, Lu), i.e. systems with competing signs of the Dzyaloshinsky vectors Fe-Fe,
+Cr-Cr and Fe-Cr. The spin Hamiltonian of the system is considered taking into
+account isotropic exchange, antisymmetric Dzyaloshinsky-Moriya exchange, and
+second- and fourth-order single-ion anisotropy. Within the framework of the
+molecular field approximation, calculations were made of the Neel temperatures,
+the average magnetic moments of $3d$ ions, total and partial magnetizations,
+and effective anisotropy constants. The existence in the model system
+YFe$_{1-x}$Cr$_x$O$_3$ of two regions of negative magnetization $0.25 \leq
+x\leq 0.5$ and $x\approx 0.8$ with the corresponding magnetization reversal
+points reaching room temperature at $x\approx 0.45$. The phenomenon of spin
+reorientation observed for single-crystal samples in a wide range of
+concentrations is explained by a sharp decrease in the contribution of
+antisymmetric exchange to magnetic anisotropy with increasing deviation from
+the parent compositions and competition between the contributions of single-ion
+anisotropy of Fe and Cr ions. It has been suggested that the spatial
+orientation of the Neel ${\bf G}$ vector and the $G_{xyz}$ configuration are
+the reason for the small value of saturation magnetization observed
+experimentally for compositions inside or near the region of negative
+magnetization.",2312.04381v2
+2023-12-12,Confined magnon dispersion in ferromagnetic and antiferromagnetic thin films in a second quantization approach: the case of Fe and NiO,"We present a methodology based on the calculation of the inelastic scattering
+from magnons via the spin scattering function in confined geometries such as
+thin films using a second quantization formalism, for both ferromagnetic and
+antiferromagnetic materials. The case studies are chosen with an aim to
+demonstrate the effects of film thickness and crystal orientation on magnon
+modes, using bcc Fe(100) and NiO with (100) and (111) crystallographic
+orientations as prototypical systems. Due to the quantization of the
+quasi-momentum we observe a granularity in the inelastic spectra in the
+reciprocal space path reflecting the orientation of the thin film. This
+approach also allows to capture softer modes that appear due to the partial
+interaction of magnetic moments close to the surface in a thin film geometry,
+in addition to bulk modes. The softer modes are also affected by
+crystallographic orientations as illustrated by the different surface-related
+peaks of NiO magnon density of states at approximately ~ 65 meV for (100) and ~
+42 meV for (111). Additionally, we explore the role of anisotropy on magnon
+modes, revealing that introducing anisotropy to both Fe and NiO films increases
+the overall hardness of the magnon modes. The introduction of a surface
+anisotropy produces a shift of the surface-related magnon DOS peak to higher
+energies with increased surface anisotropy, and in some cases leading to
+surface confined mode.",2312.07715v1
+2024-01-16,Insights into Polycrystalline Microstructure of Blood Films with 3D Mueller Matrix Imaging Approach,"We introduce a 3D Mueller Matrix (MM) image reconstruction technique using
+digital holographic approach for the layer-by-layer profiling thin films with
+polycrystalline structures, like dehydrated blood smears. The proposed method
+effectively extracts optical anisotropy parameters for a detailed quantitative
+analysis. The investigation revealed the method sensitivity to subtle changes
+in optical anisotropy properties resulting from alterations in the quaternary
+and tertiary structures of blood proteins, leading to disturbances in
+crystallization structures at the macro level at the very early stage of a
+disease. Spatial distributions of linear and circular birefringence and
+dichroism are analyzed in partially depolarizing polycrystalline blood films
+obtained from healthy tissues and cancerous prostate tissues at various stages
+of adenocarcinoma. Changes in the values of the 1st to 4th order statistical
+moments, characterizing the distributions of optical anisotropy in different
+phase sections of the smear volumes, are observed and quantified. Comparative
+analysis of optical anisotropy distributions from healthy patients highlighted
+the 3rd and 4th order statistical moments for linear and circular birefringence
+and dichroism as the most promising for diagnostic purposes. We achieved an
+excellent accuracy (>90%) for early cancer diagnosis and differentiation of its
+stages, demonstrating the techniques significant potential for rapid and
+accurate definitive cancer diagnosis compared to existing screening approaches.",2401.08340v1
+2024-02-04,Infrared Optical Anisotropy in Quasi-1D Hexagonal Chalcogenide BaTiSe3,"Polarimetric infrared detection bolsters IR thermography by leveraging the
+polarization of light. Optical anisotropy, i.e., birefringence and dichroism,
+can be leveraged to achieve polarimetric detection. Recently, giant optical
+anisotropy was discovered in quasi-1D narrow-bandgap hexagonal perovskite
+sulfides, A1+xTiS3, specifically BaTiS3[1,2] and Sr9/8TiS3[3,4]. In these
+materials, the critical role of atomic-scale structure modulations[4,5] in the
+unconventional electrical[5,6], optical[7,8], and thermal[7,9] properties
+raises the broader question of other materials that belong to this family. To
+address this issue, for the first time, we synthesized high-quality single
+crystals of a largely unexplored member of the A1+xTiX3 (X = S, Se) family,
+BaTiSe3. Single-crystal X-ray diffraction determined the room-temperature
+structure with the P31c space group, which is a superstructure of the earlier
+reported[10] P63/mmc structure. The crystal structure of BaTiSe3 features
+antiparallel c-axis displacements similar to BaTiS3,[2] but is of lower
+symmetry. Polarization-resolved Raman and Fourier transform infrared (FTIR)
+spectroscopy were used to characterize the optical anisotropy of BaTiSe3, whose
+refractive index along the ordinary (perpendicular to c) and extraordinary
+(parallel to c) optical axes was quantitatively determined by combining
+ellipsometry studies with FTIR. With a giant birefringence {\Delta}n~0.9,
+BaTiSe3 emerges as a new candidate for miniaturized birefringent optics for
+mid-wave infrared to long-wave infrared imaging.",2402.02323v1
+2024-02-04,Mass-Radius relationship of Strongly Magnetized Super-Chandrasekhar Anisotropic Deformed White Dwarf Stars in presence of $γ$-metric,"The masses and radii of strongly magnetized anisotropic deformed white dwarf
+stars are investigated using the stellar structure equations in the
+parameterized $\gamma$-metric formalism. The Equation of State (EoS) of a
+completely degenerate relativistic electron gas in strong quantizing
+density-dependent magnetic field is developed. The fluid and field pressure
+anisotropy among the parallel and perpendicular components to the magnetic
+field is taken into consideration. This anisotropy in the EoS causes
+axisymmetric deformation of the star. We found stable solutions of deformed
+super-Chandrasekhar ultramassive white dwarfs. The masses of anisotropic
+magnetized white dwarfs at the same central density decrease monotonically with
+the increase in the strength of the central magnetic field, while the
+equatorial radii increase monotonically. This is in sharp contrast to the
+isotropic case where both the mass and radius increase monotonically. High
+magnetic field increases anisotropy and oblateness. We also see that the
+maximum mass and its corresponding equatorial radius both decrease as central
+magnetic field strength increases. We also notice that the maximum mass occurs
+at higher central density as the magnetic field increases. This shows that
+increasing magnetic field (hence increasing anisotropy) softens the EoS and
+makes the star more compact.",2402.02509v1
+2024-02-19,Towards Cosmography of the Local Universe,"Anisotropies in the distance-redshift relation of cosmological sources are
+expected due to large-scale inhomogeneities in the local Universe. When the
+observed sources are tracing a large-scale matter flow in a general spacetime
+geometry, the distance-redshift relation with its anisotropies can be described
+with a geometrical prediction that generalises the well-known
+Friedmann-Lema\^itre-Robertson-Walker result. Furthermore, it turns out that a
+finite set of multipole coefficients contain the full information about a
+finite-order truncation of the distance-redshift relation of a given observer.
+The multipoles of the distance-redshift relation are interesting new
+cosmological observables that have a direct physical interpretation in terms of
+kinematical quantities of the underlying matter flow. Using light cones
+extracted from $N$-body simulations we quantify the anisotropies expected in a
+$\Lambda$ cold dark matter cosmology by running a Markov chain Monte Carlo
+analysis on the observed data. In this observational approach the survey
+selection implements an implicit smoothing scale over which the effective rest
+frame of matter is fitted. The perceived anisotropy therefore depends
+significantly on the redshift range and distribution of sources. We find that
+the multipoles of the expansion rate, as well as the observer's velocity with
+respect to the large-scale matter flow, can be determined robustly with our
+approach.",2402.12165v1
+2024-02-19,Variational properties of local functionals driven by arbitrary anisotropies,"We provide integral representation and $\Gamma$-compactness results for
+anisotropic local functionals depending on arbitrary Lipschitz continuous
+vector fields. In particular, neither bracket-generating assumptions nor linear
+independence conditions are required.",2402.12227v1
+2024-02-24,Energy landscape of noncollinear exchange coupled magnetic multilayers,"We conduct an exploration of the energy landscape of two coupled
+ferromagnetic layers with perpendicular-to-plane uniaxial anisotropy using
+finite-element micromagnetic simulations. These multilayers can be used to
+produce noncollinearity in spin-transfer torque magnetic random-access memory
+cells, which has been shown to increase the performance of this class of
+computer memory. We show that there exists a range of values of the interlayer
+exchange coupling constants for which the magnetic state of these multilayers
+can relax into two energy minima. The size of this region is determined by the
+difference in the magnitude of the layer anisotropies and is minimized when
+this difference is large. In this case, there is a wide range of experimentally
+achievable coupling constants that can produce desirable and stable
+noncollinear alignment. We investigate the energy barriers separating the local
+and global minima using string method simulations, showing that the stabilities
+of the minima increase with increasing difference in the anisotropy of the
+ferromagnetic layers. We provide an analytical solution to the location of the
+minima in the energy landscape of coupled macrospins, which has good agreement
+with our micromagnetic results for a case involving ferromagnetic layers with
+the same thickness and anisotropy, no demagnetization field, and large exchange
+stiffness. These results are important to understand how best to employ
+noncollinear coupling in the next generation of thin film magnetic devices.",2402.15910v1
+2024-03-22,Quantum spin driven Yu-Shiba-Rusinov multiplets and fermion-parity-preserving phase transition in K$_3$C$_{60}$,"Magnetic impurities in superconductors are of increasing interest due to
+emergent Yu-Shiba-Rusinov (YSR) states and Majorana zero modes for
+fault-tolerant quantum computation. However, a direct relationship between the
+YSR multiple states and magnetic anisotropy splitting of quantum impurity spins
+remains poorly characterized. By using scanning tunneling microscopy, we
+resolve systematically individual transition-metal (Fe, Cr and Ni) impurities
+induced YSR multiplets as well as their Zeeman effects in K$_3$C$_{60}$
+superconductor. The YSR multiplets show identical $d$ orbital-like wave
+functions that are symmetry-mismatched to the threefold K$_3$C$_{60}$(111) host
+surface, breaking point-group symmetries of the spatial distribution of YSR
+bound states in real space. Remarkably, we identify an unprecedented
+fermion-parity-preserving quantum phase transition between ground states with
+opposite signs of the uniaxial magnetic anisotropy that can be manipulated by
+an external magnetic field. These findings can be readily understood in terms
+of anisotropy splitting of quantum impurity spins, and thus elucidate the
+intricate interplay between the magnetic anisotropy and YSR multiplets.",2403.14970v1
+2024-03-31,On bond anisotropy for the ising model through the geometry of numbers,"We associate to each unit volume lattice of $\R^d$ the Ising model with bond
+variables equal to the inverse successive minima of that lattice. This induces
+the notion of a critical temperature for a random lattice for which
+integrability exponents are proven.",2404.00662v1
+1992-12-16,Gravity's rainbow,"Could COBE DMR be detecting the imprint from a spectrum of gravitational
+waves generated during inflation? The conventional inflationary prediction had
+been that the cosmic microwave anisotropy is dominated by energy density
+fluctuations generated during inflation and that the gravitational waves
+contribute negligibly. In this paper, we report on recent work (in
+collaboration with R. Davis, H. Hodges, and M. Turner) that has shown that the
+conventional wisdom may be wrong; specifically, gravitational waves may
+dominate the anisotropy in inflationary models where the spectrum of
+perturbations deviates significantly from scale invariance (e.g., extended and
+power-law inflation models and extreme versions of chaotic inflation). If
+gravitational waves do dominate at the large-angular scales measured by COBE
+DMR, the expectation and interpretation of anisotropies on small-angular scales
+is profoundly altered. Invited Paper for Proceedings of the Journees
+Relativistes, Amsterdam, May 14-16, 1992",9212003v1
+1993-05-26,Comparing Direct N-Body Integration with Anisotropic Gaseous Models of Star Clusters,"We compare the results for the dynamical evolution of star clusters derived
+from anisotropic gaseous models with the data from N-body simulations of
+isolated and one-component systems, each having modest number of stars. The
+statistical quality of N-body data was improved by averaging results from many
+N-body runs, each with the same initial parameters but with different sequences
+of random numbers used to initialize positions and velocities of the particles.
+We study the development of anisotropy, the spatial evolution and energy
+generation by three-body binaries and its N-dependence. We estimate the
+following free parameters of anisotropic gaseous models: the time scale for
+collisional anisotropy decay and the coefficient in the formulae for energy
+generation by three-body binaries. To achieve a fair agreement between N-body
+and gaseous models for the core in pre- as well as in post-collapse only the
+energy generation by binaries had to be varied by N. We find that anisotropy
+has considerable influence on the spatial structure of the cluster particularly
+for the intermediate and outer regions.",9305033v1
+1993-07-26,"Peculiar Velocity, Cosmic Perturbation Theory and the CMB Anisotropy","This is a somewhat extended version of the original July 93 report. It is
+proved that the cosmological density perturbation is associated with a peculiar
+velocity field. This allows a simple formulation of cosmological perturbation
+theory, which works entirely with quasi-Newtonian fluid flow equations. As an
+illustration, the large scale cosmic microwave background anisotropy
+(Sachs-Wolfe effect) is calculated without any reference to the metric
+perturbation. In addition, assuming the usual adiabatic initial condition on
+the density perturbation, we show that the dipole of the anisotropy measures
+our peculiar velocity relative to the average peculiar velocity within the last
+scattering surface of the microwave background, thus defining its frame of
+reference.",9307036v2
+1993-11-17,Early Reionization in Cosmology,"The cosmic microwave background (CMB) anisotropies have turned out to
+represent one of the most stringent 'bottle necks' for scenarios of large scale
+structure formation. As a possibility to relax this constraint, it has been
+proposed that early reionization can damp CMB fluctuations on small scales due
+to photon diffusion in the ionized plasma. As an example, I investigate the
+recently proposed scenario with cold dark matter (CDM) and texture seeds.
+There, an analysis of CMB anisotropies shows that early reionization is a
+crucial ingredient for this scenario. Without damping, the small scale
+anisotropies would dominate and exceed observed limits. In this paper I present
+analytical and numerical results for the amount of damping due to early
+reionization for CMB perturbations induced by a collapsing texture.
+Furthermore, the spectral distortion of the CMB due to Compton scattering of
+the hotter plasma electrons is calculated. Next I discuss the physical
+processes which lead to a system of coupled ordinary differential equations for
+the degree of ionization, the electron temperature and the evolution of the
+ionizing radiation.",9311039v1
+1993-11-17,Microwave Anisotropies from Texture Seeded Structure Formation,"The cosmic microwave anisotropies in a scenario of large scale structure
+formation with cold dark matter and texture are discussed and compared with
+recent observational results of the COBE satellite. A couple of important
+statistical parameters are determined. The fluctuations are slightly non
+gaussian. The quadrupole anisotropy is $1.5\pm 1.2\times 10^{-5}$ and the
+fluctuations on a angular scale of 10 degrees are $ (3.8\pm 2.6)\times
+10^{-5}$. The COBE are within about one standard deviation of the typical
+texture + CDM model discussed in this paper. Furthermore, we calculate
+fluctuations on intermediate scales (about 2 degrees) with the result $\De
+T/T(\theta \sim 2^o) = 3.9\pm 0.8)\times 10^{-5}$. Collapsing textures are
+modeled by spherically symmetric field configurations. This leads to
+uncertainties of about a factor of~2.",9311040v1
+1994-03-02,Texture-Induced Microwave Background Anisotropies,"We use numerical simulations to calculate the cosmic microwave background
+anisotropy induced by the evolution of a global texture field, with special
+emphasis on individual textures. Both spherically symmetric and general
+configurations are analysed, and in the latter case we consider field
+configurations which exhibit unwinding events and also ones which do not. We
+compare the results given by evolving the field numerically under both the
+expanded core (XCORE) and non-linear sigma model (NLSM) approximations with the
+analytic predictions of the NLSM exact solution for a spherically symmetric
+self-similar (SSSS) unwinding. We find that the random unwinding configuration
+spots' typical peak height is 60--75\% and angular size typically only 10\% of
+those of the SSSS unwinding, and that random configurations without an
+unwinding event nonetheless may generate indistinguishable hot and cold spots.
+The influence of these results on analytic estimates of texture induced
+microwave anisotropies is examined, and comparison made with other numerical
+work.",9403005v1
+1994-06-27,Beyond the Small-Angle Approximation For MBR Anisotropy from Seeds,"In this paper we give a general expression for the energy shift of massless
+particles travelling through the gravitational field of an arbitrary matter
+distribution as calculated in the weak field limit in an asymptotically flat
+space-time. It is {\it not} assumed that matter is non-relativistic. We
+demonstrate the surprising result that if the matter is illuminated by a
+uniform brightness background that the brightness pattern observed at a given
+point in space-time (modulo a term dependent on the oberver's velocity) depends
+only on the matter distribution on the observer's past light-cone. These
+results apply directly to the cosmological MBR anisotropy pattern generated in
+the immediate vicinity of of an object like a cosmic string or global texture.
+We apply these results to cosmic strings, finding a correction to previously
+published results for in the small-angle approximation. We also derive the
+full-sky anisotropy pattern of a collapsing texture knot.",9406067v1
+1994-07-01,Models of Galaxies with Central Black Holes: Adiabatic Growth in Spherical Galaxies,"We add black holes to nonrotating, spherical galaxy models, with the
+assumption that the black-hole growth is slow compared with the dynamical time
+but fast compared with the relaxation time. The outcome differs depending on
+whether the core of the initial galaxy does or does not resemble that of an
+isothermal sphere. For the isothermal case the previously-known results are
+confirmed and sharpened: the black hole induces cusps in the density ($\rho\sim
+r^{-3/2}$) and velocity dispersion ($v^2\sim r^{-1}$), and a tangential
+anisotropy in the velocity distribution away from the center. For the
+non-isothermal case the induced density cusp is steeper, and the induced
+anisotropy is larger and penetrates right to the center. The cusp around the
+black hole is insensitive to anisotropy in the initial velocity distribution,
+and also to the origin of the black hole, unless its mass comes exclusively
+from the stars of lowest angular momentum, in which case the cusp is
+suppressed. We discuss the implications for the interpretation of evidence for
+massive black holes in galactic nuclei.",9407005v1
+1994-11-29,The Cosmic Microwave Background Dipole as a Cosmological Effect,"A conventional explanation of the dipole anisotropy of the cosmic microwave
+background (CMB) radiation is in terms of the Doppler effect: our galaxy is
+moving with respect to CMB frame with $ \sim 600 ~ km ~ s^{-1} $. However, as
+the deep redshift surveys fail to reveal a convergence of the large scale flow
+to zero at distances as large as $ d \sim H^{-1} 15,000 ~ km ~ s^{-1} $ (Lauer
+& Postman, 1994), the uniqueness of the conventional interpretation has to be
+investigated. A possible alternative might be a cosmological entropy gradient,
+as suggested by Paczy\'nski & Piran (1990). We find that contrary to that
+suggestion a quadrupole anisotropy is generically of the same order of
+magnitude as the dipole anisotropy (or larger) not only for adiabatic but also
+for iso-curvature initial perturbations. Hence, the observed dipole cannot be
+explained with a very large scale perturbation which was initially
+iso-curvature.",9411111v1
+1994-12-17,Constraints onOmega from the IRAS Redshift Surveys,"We measure the anisotropy of the redshift-space power spectrum in the 1.2-Jy
+and QDOT redshift surveys of IRAS-selected galaxies. On large scales, this
+anisotropy is caused by coherent peculiar motions, and gravitational
+instability theory predicts a distortion of the power spectrum that depends
+only on the ratio $\beta \equiv f(\Omega)/b \approx \Omega^{0.6}/b$, where
+Omega is the cosmological density parameter and $b$ is the bias parameter. On
+small scales, the distortion is dominated by the random velocity dispersion in
+non-linear structures. We fit the observed anisotropy with an analytic model
+that incorporates two parameters, beta, and a small-scale velocity dispersion
+sigma_v. Tests on N-body simulations show that this model recovers beta quite
+accurately on the scales accessible to the existing IRAS redshift surveys.
+  Applying our procedure to the 1.2-Jy and QDOT surveys, we find beta=0.52 +/-
+0.13 and beta=0.54 +/- 0.3, respectively. These results imply Omega
+approximately 0.35 if galaxies trace mass, or a bias factor of about 2 if
+Omega=1.",9412062v1
+1995-05-09,Electromagnetic Origin of the CMB Anisotropy in String Cosmology,"In the inflationary scenarios suggested by string theory, the vacuum
+fluctuations of the electromagnetic field can be amplified by the
+time-evolution of the dilaton background, and can grow large enough to explain
+both the origin of the cosmic magnetic fields and of the observed CMB
+anisotropy. The normalization of the perturbation spectrum is fixed, and
+implies a relation between the perturbation amplitude at the COBE scale and the
+spectral index $n$. Working within a generic two-parameter family of
+backgrounds, a large scale anisotropy $\Delta T/T\simeq 10^{-5}$ is found to
+correspond to a spectral index in the range $n\simeq 1.11 - 1.17$.",9505041v1
+1995-05-23,GRAVITATIONAL LENSING EFFECT ON COSMIC MICROWAVE BACKGROUND ANISOTROPIES: A POWER SPECTRUM APPROACH,"The effect of gravitational lensing on cosmic microwave background (CMB)
+anisotropies is investigated using the power spectrum approach. The lensing
+effect can be calculated in any cosmological model by specifying the evolution
+of gravitational potential. Previous work on this subject is generalized to a
+non-flat universe and to a nonlinear evolution regime. Gravitational lensing
+cannot change the gross distribution of CMB anisotropies, but it may
+redistribute the power and smooth the sharp features in the CMB power spectrum.
+The magnitude of this effect is estimated using observational constraints on
+the power spectrum of gravitational potential from galaxy and cluster surveys
+and also using the limits on correlated ellipticities in distant galaxies. For
+realistic CMB power spectra the effect on CMB multipole moments is less then a
+few percent on degree angular scales, but gradually increases towards smaller
+scales. On arcminute angular scales the acoustic oscillation peaks may be
+partially or completely smoothed out because of the gravitational lensing.",9505109v2
+1995-06-12,COSMICS: Cosmological Initial Conditions and Microwave Anisotropy Codes,"COSMICS is a package of fortran programs useful for computing transfer
+functions and microwave background anisotropy for cosmological models, and for
+generating gaussian random initial conditions for nonlinear structure formation
+simulations of such models. Four programs are provided: {\bf linger\_con} and
+{\bf linger\_syn} integrate the linearized equations of general relativity,
+matter, and radiation in conformal Newtonian and synchronous gauge,
+respectively; {\bf deltat} integrates the photon transfer functions computed by
+the linger codes to produce photon anisotropy power spectra; and {\bf grafic}
+tabulates normalized matter power spectra and produces constrained or
+unconstrained samples of the matter density field.
+  Version 1.0 of COSMICS is available at http://arcturus.mit.edu/cosmics/ . The
+current release gives fortran-77 programs that run on workstations and
+vectorized supercomputers. Unix makefiles are included that make it simple to
+build and test the package. A future release will include portable parallel
+versions of the linger codes using standard message-passing libraries.",9506070v1
+1995-07-14,CMB Anisotropies in the Weak Coupling Limit,"We present a new, more powerful and accurate, analytic treatment of cosmic
+microwave background (CMB) anisotropies in the weakly coupled regime. Three
+applications are presented: gravitational redshifts in a time dependent
+potential, the Doppler effect in reionized scenarios, and the Vishniac effect.
+The Vishniac effect can dominate primary anisotropies at small angles even in
+late and minimally reionized models in flat dark-matter dominated universes
+with Harrison-Zel'dovich initial conditions. The techniques developed here
+refine previous calculations yielding a larger coherence angle for the Vishniac
+effect and moreover can be applied to non-trivial ionization histories. These
+analytic expressions may be used to modify results for the standard cold dark
+matter model to its cosmological constant and reionized extensions without
+detailed and time consuming recalculation.",9507060v1
+1995-10-20,Producing Mega-pixel CMB Maps from Differential Radiometer Data,"A major goal of cosmology is to obtain sensitive, high resolution maps of the
+Cosmic Microwave Background (CMB) anisotropy. Such maps, as would be produced
+by the recently proposed Microwave Anisotropy Probe (MAP), will contain a
+wealth of primary information about conditions in the early universe. To
+mitigate systematic effects when observing the microwave background, it is
+desirable for the raw data to be collected in differential form: as a set of
+temperature differences between points in the sky. However, the production of
+large (mega-pixel) maps from a set of temperature differences is a potentially
+severe computational challenge. We present a new technique for producing maps
+from differential radiometer data that has a computational cost that grows in
+the slowest possible way with increasing angular resolution and number of map
+pixels. The required central processor (CPU) time is proportional to the number
+of differential data points and the required random access memory (RAM) is
+proportional to the number of map pixels. We test our technique, and
+demonstrate its feasibility, by simulating one year of a space-borne anisotropy
+mission.",9510102v1
+1995-12-02,A Balloon-Borne Millimeter-Wave Telescope for Cosmic Microwave Background Anisotropy Measurements,"We report on the characteristics and design details of the Medium Scale
+Anisotropy Measurement (MSAM), a millimeter-wave, balloon-borne telescope that
+has been used to observe anisotropy in the Cosmic Microwave Background
+Radiation (CMBR) on 0\fdg5 angular scales. The gondola is capable of
+determining and maintaining absolute orientation to a few arcminutes during a
+one-night flight. Emphasis is placed on the optical and pointing performance as
+well as the weight and power budgets. We also discuss the total balloon/gondola
+mechanical system. The pendulation from this system is a ubiquitous
+perturbation on the pointing system. A detailed understanding in these areas is
+needed for developing the next generation of balloon-borne instruments.",9512006v1
+1995-12-29,Tentative Appraisal of Compatibility of Small-Scale CMB Anisotropy Detections in the Context of COBE-DMR-Normalized Open and Flat $Λ$ CDM Cosmogonies,"Goodness-of-fit statistics are used to quantitatively establish the
+compatibility of CMB anisotropy predictions in a wide range of DMR-normalized,
+open and spatially-flat $\Lambda$, CDM cosmogonies with the set of all
+presently available small-scale CMB anisotropy detection data. Conclusions
+regarding model viability depend sensitively on the prescription used to
+account for the 1$\sigma$ uncertainty in the assumed value of the DMR
+normalization, except for low-density, $\Omega_0 \sim 0.3$ -- 0.4, open models
+which are compatible with the data for all prescriptions used. While large
+baryon-density ($\Omega_B \gap 0.0175 h^{-2}$), old ($t_0 \gap 15$ -- 16 Gyr),
+low-density ($\Omega_0 \sim 0.2$ -- 0.4), flat-$\Lambda$ models might be
+incompatible, no model is incompatible with the data for all prescriptions. In
+fact, some open models seem to fit the data better than should be expected, and
+this might be an indication that some error bars are mildly overconservative.",9512168v1
+1996-01-11,Search for Supergalactic Anisotropies in the 3B Catalog,"The angular distribution of GRBs is isotropic, while the brightness
+distribution of bursts shows a reduced number of faint events. These
+observations favor a cosmological burst origin. If GRBs are indeed at
+cosmological distances and if they trace luminous matter, we must eventually
+find an anisotropic distribution of bright bursts. If a significant number of
+bursts originate at redshifts less than z~1, the concentration of nearby
+galaxies towards the supergalactic plane is pronounced enough that we could
+discover the corresponding clustering of burst locations. We used the 3B
+catalog to search for a pattern visible in supergalactic coordinates. No
+compelling evidence for anisotropies was found. The absence of anisotropies in
+SG coordinates implies a minimum sampling distance of 200h^-1 Mpc.",9601057v1
+1996-01-12,2-Point Correlations in the COBE DMR 4-Year Anisotropy Maps,"The 2-point temperature correlation function is evaluated from the 4-year
+COBE DMR microwave anisotropy maps. We examine the 2-point function, which is
+the Legendre transform of the angular power spectrum, and show that the data
+are statistically consistent from channel to channel and frequency to
+frequency. The most likely quadrupole normalization is computed for a
+scale-invariant power-law spectrum of CMB anisotropy, using a variety of data
+combinations. For a given data set, the normalization inferred from the 2-point
+data is consistent with that inferred by other methods. The smallest and
+largest normalization deduced from any data combination are 16.4 and 19.6 uK
+respectively, with a value ~18 uK generally preferred.",9601061v1
+1996-01-30,Monte Carlo Simulations of Medium-Scale CMB Anisotropy,"Recent detections of cosmic microwave background (CMB) anisotropy at
+half-degree angular scales show considerable scatter in the reported amplitude
+even at similar angular resolution. We use Monte Carlo techniques to simulate
+the current set of medium-scale CMB observations, including all relevant
+aspects of sky coverage and measurement technique. The scatter in the reported
+amplitudes is well within the range expected for the standard cold dark matter
+(CDM) cosmological model, and results primarily from the restricted sky
+coverage of each experiment. Within the context of standard CDM current
+observations of CMB anisotropy support the detection of a ``Doppler peak'' in
+the CMB power spectrum consistent with baryon density 0.01 < Omega_b < 0.13
+(95% confidence) for Hubble constant H_0 = 50 km/s/Mpc. The uncertainties are
+approximately evenly divided between instrument noise and cosmic variance
+arising from the limited sky coverage.",9601179v1
+1996-02-01,A Measurement of the Angular Power Spectrum of the Anisotropy in the Cosmic Microwave Background,"We report on a measurement of the angular power spectrum of the anisotropy in
+the Cosmic Microwave Background. The anisotropy is measured in 23 different
+multipole bands from l=54 (~3 deg) to l=404 (~0.45 deg) and in 6 frequency
+bands from 26 GHz to 46 GHz over three observing seasons. The measurements are
+consistent from year to year. The frequency spectral index of the fluctuations
+(measured at low l) is consistent with that of the CMB and inconsistent with
+either dust or Galactic free-free emission. Furthermore, the observations of
+the MSAM1-92 experiment (Cheng et al. 1994) are repeated and confirmed. The
+angular spectrum shows a distinct rise from dT_l =
+\sqrt{l(2l+1)<|a^m_l|^2>/4pi} = 49(+8,-5) \uK at l=87 to dT_l=85(+10,-8) uK at
+l = 237. These values do not include an overall +/-14\% (1sigma) calibration
+uncertainty. The analysis and possible systematic errors are discussed.",9601197v1
+1996-03-05,A CMBR Measurement Reproduced: A Statistical Comparison of MSAM1-94 to MSAM1-92,"The goal of the second flight of the Medium Scale Anisotropy Measurement
+(MSAM1-94) was to confirm the measurement of cosmic microwave background
+radiation (CMBR) anisotropy made in the first flight (MSAM1-92). The CMBR
+anisotropy and interstellar dust emission signals from the two flights are
+compared by forming the sum and difference of those portions of the data with
+the same pointings on the sky. The difference data are consistent with a null
+detection, while the summed data show significant signal. We conclude that
+MSAM1-92 and MSAM1-94 measured the same celestial signal.",9603017v1
+1996-06-21,Correlated gravitational lensing of the CMB,"Cosmological inhomogeneities gravitationally deflect radiation propagating
+from distant sources, transforming the spatial and angular correlation
+functions of intrinsic source properties. For a gaussian distribution of
+deflections (e.g. from a primordial gaussian density perturbation spectrum or
+from the central limit theorem) we calculate the probability distributions for
+geodesic deviations. If the intrinsic variable is also gaussian, e.g. the large
+scale velocity flow field or cosmic microwave background temperature
+anisotropies, then distributions and correlation functions of the observed
+image sky properties can be obtained. Specialising to CMB temperature
+fluctuations we rederive simply the influence of independent gravitational
+lensing on the anisotropy angular correlation function and calculate the new
+effect of lensing correlated with the anisotropies, e.g. arising from the same
+primordial gravitational perturbation field. Characteristic magnitudes and
+scales are given in terms of the density power spectrum. The correlated
+deflection-temperature effect is shown to be negligible.",9606141v1
+1996-07-18,Calculation of Cosmic Background Radiation Anisotropies and Implications,"We review the physical processes that are thought to produce anisotropy in
+the cosmic microwave background, focusing primarily (but not exclusively) on
+the effects of acoustic waves in the early Universe. We attempt throughout to
+supply an intuitive, physical picture of the key ideas and to elucidate the
+ways in which the predicted anisotropy depends on cosmological parameters such
+as Omega and h. The second half of these lectures is devoted to a discussion of
+microwave background data analysis techniques, with an emphasis on the analysis
+of the COBE DMR data. In particular, the Karhunen-Loeve method of data
+compression is described in detail.",9607088v1
+1996-08-15,Depolarization of the cosmic microwave background by a primordial magnetic field and its effect upon temperature anisotropy,"We estimate the depolarizing effect of a primordial magnetic field upon the
+cosmic microwave background radiation due to differential Faraday rotation
+across the last scattering surface. The degree of linear polarization of the
+CMB is significantly reduced at frequencies around and below 30 GHz $(B_*
+/10^{-2}{\rm Gauss})^{1/2}$, where $B_*$ is the value of the primordial field
+at recombination. The depolarizing mechanism reduces the damping of
+anisotropies due to photon diffusion on small angular scales. The $l\approx
+1000$ multipoles of the CMB temperature anisotropy correlation function in a
+standard cold dark matter cosmology increase by up to 7.5\% at frequencies
+where depolarization is significant.",9608098v1
+1997-01-24,Cosmic Microwave Background Anisotropy in the COBE DMR 4-yr Sky Maps,"The COBE satellite has provided the only comprehensive multi-frequency
+full-sky observations of the microwave sky available today. Assessment of the
+observations requires a detailed likelihood analysis to extract the maximum
+amount of information present in the noisy data. I present a specific method
+for estimating the CMB anisotropy power spectrum independent of any assumptions
+about the underlying cosmology, and then use standard image processing
+techniques to generate the most revealing corresponding maps of the signal. The
+consistency of the data at the available frequencies provides strong support to
+the assertion that we are being provided with our first glimpse of the last
+scattering surface.",9701191v1
+1997-01-27,Polarization of the CMB photons crossing the galaxy clusters,"In this paper, I investigate a local effect of polarization of the Cosmic
+Microwave Background (CMB) in clusters of galaxies, due to the Thomson
+scattering of the anisotropic radiation. A local anisotropy of the CMB is
+produced by some gravitational and scattering effects, as, for instance, the
+Sunyaev Zel'dovich effect, the Doppler shift due to the cluster motion and the
+gravitational lensing. The resulting anisotropy $\Delta I / I$ depends on the
+physical properties of the clusters, in particular on their emissivity in the X
+band, their size, their gravitational potential and on the peculiar conditions
+characterizing the cluster gas. By solving the Boltzmann radiative transfer
+equation in presence of such anisotropies I calculate the average polarization
+at the centre of some clusters, namely A2218, A576 and A2163, whose properties
+are quite well known. I prove the gravitational effects due to the contraction
+or to the expansion of the cluster have some importance and dominate the SZ
+effect, particularly for high density stuctures.",9701203v1
+1997-02-14,Anisotropies in the Cosmic Microwave Background: Theory,"Anisotropies in the Cosmic Microwave Background (CMB) contain a wealth of
+information about the past history of the universe and the present values of
+cosmological parameters. I ouline some of the theoretical advances of the last
+few years. In particular, I emphasize that for a wide class of cosmological
+models, theorists can accurately calculate the spectrum to better than a
+percent. The specturm of anisotropies today is directly related to the pattern
+of inhomogeneities present at the time of recombination. This recognition leads
+to a powerful argument that will enable us to distinguish inflationary models
+from other models of structure formation. If the inflationary models turn out
+to be correct, the free parameters in these models will be determined to
+unprecedented accuracy by the upcoming satellite missions.",9702134v1
+1997-02-20,Wall fluctuation modes and tensor CMB anisotropy in open inflation models,"We calculate the spectrum of large angle cosmic microwave background (CMB)
+anisotropies due to quantum fluctuations of the gravitational wave modes in
+one-bubble open inflation models. We find the bubble-wall fluctuation modes,
+which had been thought to exist discretely in previous analyses, are actually
+contained in the continuous spectrum of gravitational wave modes when the
+gravitational coupling is correctly taken into account. Then we find that the
+spectrum of the tensor CMB anisotropy can be decomposed into the part due to
+the wall fluctuation modes and that due to the usual gravitational wave modes
+in a way which is almost model-independent, even when the gravitational
+coupling is strong. We also discuss observational constraints on the model
+parameters. We find that an appreciable portion of the parameter space is
+excluded but the remaining allowable region is still wide enough to leave the
+one-bubble scenario viable.",9702174v1
+1997-03-18,Getting Around Cosmic Variance,"Cosmic microwave background (CMB) anisotropies probe the primordial density
+field at the edge of the observable Universe. There is a limiting precision
+(``cosmic variance'') with which anisotropies can determine the amplitude of
+primordial mass fluctuations. This arises because the surface of last scatter
+(SLS) probes only a finite two-dimensional slice of the Universe. Probing other
+SLSs observed from different locations in the Universe would reduce the cosmic
+variance. In particular, the polarization of CMB photons scattered by the
+electron gas in a cluster of galaxies provides a measurement of the CMB
+quadrupole moment seen by the cluster. Therefore, CMB polarization measurements
+toward many clusters would probe the anisotropy on a variety of SLSs within the
+observable Universe, and hence reduce the cosmic-variance uncertainty.",9703118v1
+1997-04-28,Integral Solution for the Microwave Background Anisotropies in Non-fl at Universes,"We present an efficient method to compute CMB anisotropies in non-flat
+universes. First we derive the Boltzmann equation for cosmic microwave
+background temperature and polarization fluctuations produced by scalar
+perturbations in a general Robertson-Walker universe. We then apply the
+integral method to solve this equation, writing temperature and polarization
+anisotropies as a time integral over a geometrical term and a source term. The
+geometrical terms can be written using ultra-spherical Bessel functions, which
+depend on curvature. These cannot be precomputed in advance as in flat space.
+Instead we solve directly their differential equation for selected values of
+the multipoles. The resulting computational time is comparable to the flat
+space case and improves over previous methods by 2-3 orders of magnitude. This
+allows one to compute highly accurate CMB temperature and polarization spectra,
+matter transfer functions and their CMB normalizations for any cosmological
+model, thereby avoiding the need to use various approximate fitting formulae
+that exist in the literature.",9704265v2
+1997-05-19,The Cosmic Microwave Background Anisotropy Experiments,"This paper reports a summary of the contents contents of six hours of
+lectures on the CMB anisotropy experiments given at the Strasbourg NATO school
+on the CMB and cosmology. (Its companion paper, astro-ph/9705101 reports the
+lectures on the CMB spectrum.) A context is set as a bridge from the
+theoretical CMB anisotropy lectures and the experimental situation. The COBE
+DMR results are reveiwed in detail and as pioneer for future space missions.
+Current and planned experiments are discussed in preference to reviewing
+already completed observations. The NASA MidEX mission MAP is discussed in some
+detail including figures. The ESA M3 mission Max Planck Surveyor is also
+reviewed in some detail though its final configuration is not yet fully
+settled. The recent history and current versions are presented. Tables and
+references for experiments are included.",9705135v1
+1997-11-27,"Constraints on the chaotic inflationary scenario with a nonminimally coupled ""inflaton"" field from the cosmic microwave background radiation anisotropy","We investigate a possibility to restrict the chaotic inflationary scenario
+with ""large"" nonminimally coupled inflaton(""phi"") field considered by Fakir and
+Unruh by means of the observed CMBR anisotropy. We calculate the contributions
+of the long wavelength gravitational waves generated in the inflationary period
+to CMBR anisotropy quadrupole moment. We obtain the constraint lambda/(xi^2) =
+1.8 X 10^(-8)/psi_i, where ""lambda"" is the self coupling, ""xi"" is the
+nonminimal coupling constant and ""psi_i"" means the initial value of psi =
+8piG(phi^2). Combining this with previously obtained constraint that 2.1 times
+squre root of lambda/(xi^2) = dT/T = 1.1 X 10^(-5), we conclude that the
+initial value has to be psi_i = 1.6 X 10^3. If the self-coupling has a
+reasonably values of order 10^(-2), then xi = 10^4 and phi_i = 10^(-1) times
+Planck mass.",9711340v1
+1998-01-28,The Effect of the Detector Response Time on Bolometric Cosmic Microwave Background Anisotropy Experiments,"We analyze the effects of the detector response time on bolometric
+measurements of the anisotropy of the cosmic microwave background (CMB). We
+quantify the effect in terms of a single dimensionless parameter $L$ defined as
+the ratio between the time the beam sweeps its own size and the bolometer
+response time. As $L$ decreases below $\sim 2.5$ the point source response of
+the experiment becomes elongated. We introduce a window function matrix based
+on the timestream data to assess the effects of the elongated beam. We find
+that the values of the window function matrix elements decrease slowly as a
+function $L$. Our analysis and results apply to other cases of beam asymmetry.
+For the High Frequency Instrument on board the Planck Surveyor satellite we
+show that for a broad range of $L$ the ability of the experiment to extract the
+cosmological parameters is not degraded. Our analysis enhances the flexibility
+in tuning the design parameters of CMB anisotropy experiments.",9801291v2
+1998-03-15,Cosmological-Parameter Determination With Cosmic Microwave Background Temperature Anisotropies and Polarization,"Forthcoming cosmic microwave background experiments (CMB) will provide
+precise new tests of structure-formation theories. The geometry of the Universe
+may be determined robustly, and the classical cosmological parameters, such as
+the cosmological constant, baryon density, and Hubble constant, may be
+determined as well. In addition, the ``inflationary observables,'' which
+parameterize the shapes and amplitudes of the primordial spectra of density
+perturbations and long-wavelength gravitational waves produced by inflation,
+may also be measured and thus provide several new tests of inflation. Although
+most attention has focussed on the more easily observed temperature
+anisotropies, recent work has shown that the CMB polarization provides a wealth
+of unique information that may be especially important for determination of the
+inflationary observables. Secondary anisotropies at small angular scales
+produced by re-scattering of photons from partial reionization may be used to
+constrain the ionization history of the Universe.",9803168v1
+1998-04-04,Probing Cosmic topology using CMB anisotropy,"The measurements of CMB anisotropy have opened up a window for probing the
+global topology of the universe on length scales comparable to and beyond the
+Hubble radius. We have developed a new method for calculating the CMB
+anisotropy in models with nontrivial topology and apply it to open universe
+models with compact spatial topology. We conduct a Bayesian probability
+analysis for a selection of models which confronts the theoretical pixel-pixel
+temperature correlation function with the COBE-DMR data. Our results
+demonstrate that strong constraints on compactness arise: if the universe is
+small compared to the `horizon' size, correlations appear in the maps that are
+irreconcilable with the observations.",9804042v1
+1998-04-16,A covariant and gauge-invariant analysis of cosmic microwave background anisotropies from scalar perturbations,"We present a new, fully covariant and manifestly gauge-invariant expression
+for the temperature anisotropy in the cosmic microwave background radiation
+resulting from scalar perturbations. We pay particular attention to gauge
+issues such as the definition of the temperature perturbation and the placing
+of the last scattering surface. In the instantaneous recombination
+approximation, the expression may be integrated up to a Rees-Sciama term for
+arbitrary matter descriptions in flat, open and closed universes. We discuss
+the interpretation of our result in the baryon-dominated limit using numerical
+solutions for conditions on the last scattering surface, and confirm that for
+adiabatic perturbations the dominant contribution to the anisotropy on
+intermediate scales (the location of the Doppler peaks) may be understood in
+terms of the spatial inhomogeneity of the radiation temperature in the baryon
+rest frame. Finally, we show how this term enters the usual Sachs-Wolfe type
+calculations (it is rarely seen in such analyses) when subtle gauge effects at
+the last scattering surface are treated correctly.",9804150v1
+1998-04-24,Small-scale anisotropy of the cosmic background radiation and scattering by cloudy plasma,"If the first stars formed soon after decoupling of baryons from the thermal
+cosmic background radiation (CBR), the radiation may have been last scattered
+in a cloudy plasma. We discuss the resulting small-scale anisotropy of the CBR
+in the limit where the plasma clouds are small compared to the mean distance
+between clouds along a line of sight. This complements the perturbative
+analysis valid for mildly nonlinear departures from homogeneity at last
+scattering. We conclude that reasonable choices for the cloud parameters imply
+CBR anisotropy consistent with the present experimental limits, in agreement
+with the perturbative approach. This means the remarkable isotropy of the CBR
+need not contradict the early small-scale structure formation predicted in some
+cosmogonies.",9804260v1
+1998-04-28,Cosmic microwave background anisotropies in the CDM model: a covariant and gauge-invariant approach,"We present a fully covariant and gauge-invariant calculation of the evolution
+of anisotropies in the cosmic microwave background (CMB) radiation. We use the
+physically appealing covariant approach to cosmological perturbations, which
+ensures that all variables are gauge-invariant and have a clear physical
+interpretation. We derive the complete set of frame-independent, linearised
+equations describing the (Boltzmann) evolution of anisotropy and inhomogeneity
+in an almost Friedmann-Robertson-Walker (FRW) cold dark matter (CDM) universe.
+These equations include the contributions of scalar, vector and tensor modes in
+a unified manner. Frame-independent equations for scalar and tensor
+perturbations, which are valid for any value of the background curvature, are
+obtained straightforwardly from the complete set of equations. We discuss the
+scalar equations in detail, including the integral solution and relation with
+the line of sight approach, analytic solutions in the early radiation dominated
+era, and the numerical solution in the standard CDM model. Our results confirm
+those obtained by other groups, who have worked carefully with non-covariant
+methods in specific gauges, but are derived here in a completely transparent
+fashion.",9804301v2
+1998-08-16,Cosmic microwave background anisotropies: Nonlinear dynamics,"We develop a new approach to local nonlinear effects in cosmic microwave
+background anisotropies, and discuss the qualitative features of these effects.
+New couplings of the baryonic velocity to radiation multipoles are found,
+arising from nonlinear Thomson scattering effects. We also find a new nonlinear
+shear effect on small angular scales. The full set of evolution and constraint
+equations is derived, including the nonlinear generalizations of the radiation
+multipole hierarchy, and of the dynamics of multi-fluids. These equations
+govern radiation anisotropies in any inhomogeneous spacetime, but their main
+application is to second-order effects in a universe that is close to the
+Friedmann models. Qualitative analysis is given here, and quantitative
+calculations are taken up in further papers.",9808163v2
+1998-10-16,Reconstructing Projected Matter Density from Cosmic Microwave Background,"Gravitational lensing distorts the cosmic microwave background (CMB)
+anisotropies and imprints a characteristic pattern onto it. The distortions
+depend on the projected matter density between today and redshift $z \sim
+1100$. In this paper we develop a method for a direct reconstruction of the
+projected matter density from the CMB anisotropies. This reconstruction is
+obtained by averaging over quadratic combinations of the derivatives of CMB
+field. We test the method using simulations and show that it can successfully
+recover projected density profile of a cluster of galaxies if there are
+measurable anisotropies on scales smaller than the characteristic cluster size.
+In the absence of sufficient small scale power the reconstructed maps have low
+signal to noise on individual structures, but can give a positive detection of
+the power spectrum or when cross correlated with other maps of large scale
+structure. We develop an analytic method to reconstruct the power spectrum
+including the effects of noise and beam smoothing. Tests with Monte Carlo
+simulations show that we can recover the input power spectrum both on large and
+small scales, provided that we use maps with sufficiently low noise and high
+angular resolution.",9810257v1
+1998-11-10,Temperature Anisotropies and Distortions Induced by Hot Intracluster Gas on the Cosmic Microwave Background,"The power spectrum of temperature anisotropies induced by hot intracluster
+gas on the cosmic background radiation is calculated. For low multipoles it
+remains constant while at multipoles above $l>2000$ it is exponentially damped.
+The shape of the radiation power spectrum is almost independent of the average
+intracluster gas density profile, gas evolution history or clusters virial
+radii; but the amplitude depends strongly on those parameters and could be as
+large as 20% that of intrinsic contribution. The exact value depends on the
+global properties of the cluster population and the evolution of the
+intracluster gas. The distortion on the Cosmic Microwave Background black body
+spectra varies in a similar manner. The ratio of the temperature anisotropy to
+the mean Comptonization parameters is shown to be almost independent of the
+cluster model and, in first approximation, depends only on the number density
+of clusters.",9811158v1
+1999-02-04,Cosmic Microwave Background Anisotropy Window Functions Revisited,"The primary results of most observations of cosmic microwave background (CMB)
+anisotropy are estimates of the angular power spectrum averaged through some
+broad band, called band-powers. These estimates are in turn what are used to
+produce constraints on cosmological parameters due to all CMB observations.
+Essential to this estimation of cosmological parameters is the calculation of
+the expected band-power for a given experiment, given a theoretical power
+spectrum. Here we derive the ""band power"" window function which should be used
+for this calculation, and point out that it is not equivalent to the window
+function used to calculate the variance. This important distinction has been
+absent from much of the literature: the variance window function is often used
+as the band-power window function. We discuss the validity of this assumed
+equivalence, the role of window functions for experiments that constrain the
+power in {\it multiple} bands, and summarize a prescription for reporting
+experimental results. The analysis methods detailed here are applied in a
+companion paper to three years of data from the Medium Scale Anisotropy
+Measurement.",9902046v2
+1999-03-30,CMB Anisotropy in Compact Hyperbolic Universes,"Measurements of CMB anisotropy are ideal experiments for discovering the
+non-trivial global topology of the universe. To evaluate the CMB anisotropy in
+multiply-connected compact cosmological models, one needs to compute eigenmodes
+of the Laplace-Beltrami operator. We numerically obtain the eigenmodes on a
+compact 3-hyperbolic space cataloged as $m003(-2,3)$ in SnapPea (computer
+program by Jeff Weeks) using the direct boundary element method, which enables
+one to simulate the CMB in multiply-connected compact models with high
+precision. The angular power spectra $C_{l}$'s ($2 \leq l\leq18$) are
+calculated using computed eigenmodes for $5.4\leqk<10$ and Gaussian random
+approximation for the expansion coefficients for $10\leqk<20$. Assuming that
+the initial power spectrum is the Harrison-Zeldovich spectrum, the computed
+$C_l$'s are consistent with the COBE data for $0.1 \leq\Omega_o \leq 0.6$.
+  In low $\Omega_o$ models, the large-angular fluctuations can be produced at
+periods after the last scattering as the curvature perturbations decay in the
+curvature dominant era.",9903446v2
+1999-04-19,Overview of Secondary Anisotropies of the CMB,"While the major contribution to the Cosmic Microwave Background (CMB)
+anisotropies are the sought-after primordial fluctuations produced at the
+surface of last scattering, other effects produce secondary fluctuations at
+lower redshifts. These secondary fluctuations must be carefully accounted for,
+in order to isolate primordial fluctuations. In addition, they are interesting
+in their own right, since they provide a wealth of information on the geometry
+and local properties of the universe. Here, I survey the different sources of
+secondary anisotropies and extragalactic foregrounds of the CMB. I show their
+relative importance on the multipole-frequency plane. I discuss in particular
+their impact in the future CMB missions MAP and Planck Surveyor.",9904235v1
+1999-04-26,Constraining the equation of state of the Universe from Distant Type Ia Supernovae and Cosmic Microwave Background Anisotropies,"We analyse the constraints that can be placed on a cosmological constant or
+quintessence-like component by combining observations of Type Ia supernovae
+with measurements of anisotropies in the cosmic microwave background. We use
+the recent supernovae sample of Perlmutter et al and observations of the CMB
+anisotropies to constraint the equation of state (w_Q = p/rho) in
+quintessence-like models via a likelihood analysis. The 2 sigma upper limits
+are w_Q < -0.6 if the Universe is assumed to be spatially flat, and w_Q < -0.4
+for universes of arbitrary spatial curvature. The upper limit derived for a
+spatially flat Universe is close to the lower limit (w_Q approx -0.7) allowed
+for simple potentials, implying that additional fine tuning may be required to
+construct a viable quintessence model.",9904356v1
+1999-05-20,Models of Universe with an inhomogeneous Big Bang singularity. II. CMBR dipole anisotropy as a byproduct of a conic Big Bang singularity,"The existence of stars and galaxies reqires cosmological models with an
+inhomogeneous matter and radiation distribution. But in these models the
+initial singularity surface t_0(r) is in general homogeneous (independent of
+r). In this second paper of a series devoted to an inhomogeneous Big Bang
+singularity, we investigate the cosmic microwave background radiation (CMBR)
+dipole. A special Tolman-Bondi Universe is used to study the effect of a
+Big-Bang singularity, depending linearly on r, on the CMBR anisotropy. It is
+shown that, for an observer located off the ``center'' of this Universe (r=0),
+the parameters of the model can be tuned so as to reproduce, with a good
+approximation, the dipole and the quadrupole moments of the CMBR anisotropy
+observed in recent experiments. If the dipole should prove cosmological, a
+slight delaying of the Big-Bang over spatial coordinates would thus be a good
+candidate for its interpretation.",9905262v1
+1999-06-25,Correlations in the Far Infrared Background,"We compute the expected angular power spectrum of the cosmic Far Infrared
+Background (FIRB). We find that the signal due to source correlations dominates
+the shot--noise for $\ell \la 1000$ and results in anisotropies with rms
+amplitudes $(\sqrt{\ell(\ell+1)C_\ell/2\pi})$ between 5% and 10% of the mean
+for $l \ga 150$. The angular power spectrum depends on several unknown
+quantities, such as the UV flux density evolution, optical properties of the
+dust, biasing of the sources of the FIRB, and cosmological parameters. However,
+when we require our models to reproduce the observed DC level of the FIRB, we
+find that the anisotropy is at least a few percent in all cases. This
+anisotropy is detectable with proposed instruments, and its measurement will
+provide strong constraints on models of galaxy evolution and large-scale
+structure at redshifts up to at least $z \sim5$.",9906399v3
+1999-10-19,On the Numerical Study of the Complexity and Fractal Dimension of CMB Anisotropies,"We consider the problem of numerical computation of the Kolmogorov complexity
+and the fractal dimension of the anisotropy spots of Cosmic Microwave
+Background (CMB) radiation. Namely, we describe an algorithm of estimation of
+the complexity of spots given by certain pixel configuration on a grid and
+represent the results of computations for a series of structures of different
+complexity. Thus, we demonstrate the calculability of such an abstract
+descriptor as the Kolmogorov complexity for CMB digitized maps. The correlation
+of complexity of the anisotropy spots with their fractal dimension is revealed
+as well. This technique can be especially important while analyzing the data of
+the forthcoming space experiments.",9910338v1
+1999-11-25,CMB Anisotropies due to Feedback-Regulated Inhomogeneous Reionization,"We calculate the secondary anisotropies in the CMB produced by inhomogeneous
+reionization from simulations in which the effects of radiative and stellar
+feedback effects on galaxy formation have been included. This allows to
+self-consistently determine the beginning ($z_i\approx 30$), the duration ($
+\delta z\approx 20$) and the (nonlinear) evolution of the reionization process
+for a critical density CDM model. In addition, from the simulated spatial
+distribution of ionized regions, we are able to calculate the evolution of the
+two-point ionization correlation function, $C_\chi$, and obtain the power
+spectrum of the anisotropies, $C_\ell$, in the range $5000 < \ell < 10^6$. The
+power spectrum has a broad maximum around $\ell \approx 30000$, where it
+reaches the value $2\times 10^{-12}$. We also show that the angular correlation
+function $C(\theta)$ is not Gaussian, but at separation angles $% \theta
+\lower.5ex\hbox{\ltsima} 10^{-4}$ rad it can be approximated by a modified
+Lorentzian shape; at larger separations an anticorrelation signal is predicted.
+Detection of signals as above will be possible with future mm-wavelength
+interferometers like ALMA, which appears as an optimum instrument to search for
+signatures of inhomogeneous reionization.",9911467v1
+1999-12-02,Cosmic Glows,"This is the obligatory Cosmic Microwave Background review. I discuss the
+current status of CMB anisotropies, together with some points on the related
+topic of the Far-Infrared Background. We have already learned a number of
+important things from CMB anisotropies. Models which are in good shape have:
+approximately flat geometry; cold dark-matter, plus something like a
+cosmological constant; roughly scale invariant adiabatic fluctuations; and
+close to Gaussian statistics. The constraints from the CMB are beginning to be
+comparable to those from other cosmological measurements. With a wealth of new
+data coming in, it is expected that CMB anisotropies will soon provide the most
+stringent limits on fundamental cosmological parameters, as well as probing
+high energy particle physics and the Dark Ages of astrophysics. Nudge, nudge.
+Wink, wink. Say no more.",9912038v1
+2000-02-29,CMB Anisotropies: A Decadal Survey,"We review the theoretical implications of the past decade of CMB anisotropy
+measurements, which culminated in the recent detection of the first feature in
+the power spectrum, and discuss the tests available to the next decade of
+experiments. The current data already suggest that density perturbations
+originated in an inflationary epoch, the universe is spatially flat, and
+baryonic dark matter is required. We discuss the underlying assumptions of
+these claims and outline the tests required to ensure they are robust. The most
+critical test - the presence of a second feature at the predicted location -
+should soon be available. Further in the future, secondary anisotropies and
+polarization should open new windows to the early and low(er) redshift
+universe.",0002520v1
+2000-07-06,On the effect of coronal outflow on spectra formation in galactic black hole systems,"We present the results of both analytical and numerical calculations of the
+amplitude of the reflection component in X-ray spectra of galactic black hole
+systems. We take into account the anisotropy of Compton scattering and the
+systematic relativistic bulk motion of the hot plasma. In the case of single
+scattering approximation the reflection from the disc surface is significantly
+enhanced due to the anisotropy of Compton scattering. On the other hand the
+calculations of multiple scattering obtained using the Monte Carlo method show
+that the anisotropy effect is much weaker in that case. Therefore, the enhanced
+backscattered flux may affect the observed spectra only if the disc surface is
+highly ionized, which reduces the absorption in the energy band corresponding
+to the first Compton scattering.",0007070v1
+2000-07-31,Gravitational Time Delay Effects on CMB Anisotropies,"We study the effect of gravitational time delay on the power spectra and
+bispectra of the cosmic microwave background (CMB) temperature and polarization
+anisotropies. The time delay effect modulates the spatial surface at
+recombination on which temperature anisotropies are observed, typically by ~1
+Mpc. While this is a relatively large shift, its observable effects in the
+temperature and polarization fields are suppressed by geometric considerations.
+The leading order effect is from its correlation with the closely related
+gravitational lensing effect. The change to the temperature-polarization cross
+power spectrum is of order 0.1% and is hence comparable to the cosmic variance
+for the power in the multipoles around l~1000. While unlikely to be extracted
+from the data in its own right, its omission in modeling would produce a
+systematic error comparable to this limiting statistical error and, in
+principle, is relevant for future high precision experiments. Contributions to
+the bispectra result mainly from correlations with the Sachs-Wolfe effect and
+may safely be neglected in a low density universe.",0008001v1
+2000-11-07,From Anisotropy to Omega,"Following the recent measurement of the acoustic peak by the BOOMERanG and
+MAXIMA experiments in the CMB anisotropy angular power spectrum, many analyses
+have found that the geometry of the Universe is very close to flat, but
+slightly closed models are favoured. In this paper we will briefly review how
+the CMB anisotropies depend on the curvature, explaining any assumptions we
+could make and showing that this skewness towards closed models can be easily
+explained by degeneracies in the cosmological parameters. While it is difficult
+to give independent constraints on the cosmological constant and/or different
+forms of dark energies, we will also show that combining CMB measurements with
+other observational data will introduce new and tighter constraints, like
+$\Omega_\Lambda > 0$ at high significance.",0011147v2
+2001-01-05,Constraints from the damping tail,"The detection of anisotropy in the cosmic microwave background on arcminute
+scales by the Cosmic Background Imager (CBI) provides us with our first
+measurement of the damping tail and closes one chapter in the CMB story. We now
+have experimental verification for all of the features in the temperature
+anisotropy spectrum predicted theoretically two decades ago. The CBI result
+allows us to constrain both parameterized models based on the inflationary cold
+dark matter (CDM) paradigm and to examine model independent constraints on the
+matter content, the distance to last scattering and the thickness of the last
+scattering surface. By providing a lower limit on the duration of recombination
+it implies a lower limit on the polarization of the sub-degree scale anisotropy
+which is close to current experimental upper limits.",0101086v2
+2001-04-03,Finding out the velocity anisotropy parameter for some globular clusters: the case of stationary model,"The problem of determination of the velocity anisotropy parameter (A) from
+star density profiles in globular clusters is considered. The calculations are
+performed for following clusters: M3, M12, M13, M15, M55, M56, Palomar 3,
+Palomar 14, NGC5139 (Omega Centauri) and NGC6535. We found that for most
+clusters is A=0. For M56 the parameter is calculated at limiting magnitudes
+B=21.5 and B=19.0 and we found A=0.8 and A=0.3 respectively. For Omega Centauri
+the anisotropy parameter is determined in three separate regions and we found:
+A=0 for central region, A=0.1 for middle region and A=0.3 for halo.",0104038v1
+2001-04-06,The Tensor to Scalar Ratio of Phantom Dark Energy Models,"We investigate the anisotropies in the cosmic microwave background in a class
+of models which possess a positive cosmic energy density but negative pressure,
+with a constant equation of state w = p/rho < -1. We calculate the temperature
+and polarization anisotropy spectra for both scalar and tensor perturbations by
+modifying the publicly available code CMBfast. For a constant initial curvature
+perturbation or tensor normalization, we have calculated the final anisotropy
+spectra as a function of the dark energy density and equation of state w and of
+the scalar and tensor spectral indices. This allows us to calculate the
+dependence of the tensor-to-scalar ratio on w in a model with phantom dark
+energy, which may be important for interpreting any future detection of
+long-wavelength gravitational waves.",0104112v1
+2001-08-12,CMB Analysis,"We describe the subject of Cosmic Microwave Background (CMB) analysis - its
+past, present and future. The theory of Gaussian primary anisotropies, those
+arising from linear physics operating in the early Universe, is in reasonably
+good shape so the focus has shifted to the statistical pipeline which confronts
+the data with the theory: mapping, filtering, comparing, cleaning, compressing,
+forecasting, estimating. There have been many algorithmic advances in the
+analysis pipeline in recent years, but still more are needed for the forecasts
+of high precision cosmic parameter estimation to be realized. For secondary
+anisotropies, those arising once nonlinearity develops, the computational state
+of the art currently needs effort in all the areas: the Sunyaev-Zeldovich
+effect, inhomogeneous reionization, gravitational lensing, the Rees-Sciama
+effect, dusty galaxies. We use the Sunyaev-Zeldovich example to illustrate the
+issues. The direct interface with observations for these non-Gaussian signals
+is much more complex than for Gaussian primary anisotropies, and even more so
+for the statistically inhomogeneous Galactic foregrounds. Because all the
+signals are superimposed, the separation of components inevitably complicates
+primary CMB analyses as well.",0108204v1
+2001-10-18,Cosmic Microwave Background Anisotropies,"Cosmic microwave background (CMB) temperature anisotropies have and will
+continue to revolutionize our understanding of cosmology. The recent discovery
+of the previously predicted acoustic peaks in the power spectrum has
+established a working cosmological model: a critical density universe
+consisting of mainly dark matter and dark energy, which formed its structure
+through gravitational instability from quantum fluctuations during an
+inflationary epoch. Future observations should test this model and measure its
+key cosmological parameters with unprecedented precision. The phenomenology and
+cosmological implications of the acoustic peaks are developed in detail. Beyond
+the peaks, the yet to be detected secondary anisotropies and polarization
+present opportunities to study the physics of inflation and the dark energy.
+The analysis techniques devised to extract cosmological information from
+voluminous CMB data sets are outlined, given their increasing importance in
+experimental cosmology as a whole.",0110414v1
+2001-11-15,Temperature Isotropization in Solar Flare Plasmas due to the Electron Firehose Instability,"The isotropization process of a collisionless plasma with an electron
+temperature anisotropy along an external magnetic field ($T_\| ^e\gg
+T_\perp^e$, $\|$ and $\perp$ with respect to the background magnetic field) and
+isotropic protons is investigated using a particle-in-cell(PIC) code.
+Restricting wave growth mainly parallel to the external magnetic field, the
+isotropization mechanism is identified to be the Electron Firehose Instability
+(EFI). The free energy in the electrons is first transformed into left-hand
+circularly polarized transverse low-frequency waves by a non-resonant
+interaction. Fast electrons can then be scattered towards higher perpendicular
+velocities by gyroresonance, leading finally to a complete isotropization of
+the velocity distribution. During this phase of the instability, Langmuir waves
+are generated which may lead to the emission of radio waves. A large fraction
+of the protons is resonant with the left-hand polarized electromagnetic waves,
+creating a proton temperature anisotropy $T_\|^p < T_\perp^p$. The parameters
+of the simulated plasma are chosen compatible to solar flare conditions. The
+results indicate the significance of this mechanism in the particle
+acceleration context: The EFI limits the anisotropy of the electron velocity
+distribution, and thus provides the necessary condition for further
+acceleration. It enhances the pitch-angle of the electrons and heats the ions.",0111303v1
+2001-12-03,The CMB - Contemporary Measurements and Cosmology,"Since the discovery of the Cosmic Microwave Background (CMB) in 1965,
+characterization of the CMB anisotropy angular power spectrum has become
+somewhat of a holy grail for experimental cosmology. Because CMB anisotropy
+measurements are difficult, the full potential of the CMB is only now being
+realized. Improvements in experimental techniques and detector technology have
+yielded an explosion of progress in the past couple of years resulting in the
+ability to use measurements of the CMB to place meaningful constraints on
+cosmological parameters. In this review, I discuss the theory behind the CMB
+but focus primarily on the experiments, reviewing briefly the history of CMB
+anisotropy measurements and focusing on the recent experiments that have
+revolutionized this field. Results from these modern experiments are reviewed
+and the cosmological implications discussed. I conclude with brief comments
+about the future of CMB physics.",0112052v1
+2002-03-04,After Acoustic Peaks: What's Next in CMB?,"The advent of high signal-to-noise cosmic microwave background (CMB)
+anisotropy experiments has allowed detailed studies on the power spectrum of
+temperature fluctuations. The existence of acoustic oscillations in the
+anisotropy power spectrum is now established with the detection of the first
+two, and possibly the third, peaks. Beyond the acoustic peak structure, we
+consider cosmological and astrophysical information that can be extracted by
+pushing anisotropy observations to fine angular scales with higher resolution
+instruments. At small scales, a variety of contributions allow the use of CMB
+photons as a probe of the large scale structure: we outline possible studies
+related to understanding detailed physical properties such as the distribution
+of dark matter, baryons and pressure, and ways to measure the peculiar,
+transverse and rotational velocities of virialized halos such as galaxy
+clusters. Beyond the temperature, we consider several useful aspects of the CMB
+polarization and comment on an ultimate goal for future CMB experiments
+involving the direct detection of inflationary gravity-waves through their
+distinct signature in the curl-type polarization.",0203048v3
+2002-03-21,Detection of the velocity dipole in the radio galaxies of the NRAO VLA Sky Survey,"We are in motion against the cosmic backdrop. This motion is evidenced by the
+systematic temperature shift - or dipole anisotropy - observed in the Cosmic
+Microwave Background radiation (CMB). Because of the Doppler effect, the
+temperature of the CMB is 0.1 per cent higher in our direction of motion
+through the Universe. If our standard cosmological understanding is correct,
+this dipole should also be present as an enhancement in the surface density of
+distant galaxies. The main obstacle in finding this signal is the very uneven
+distribution of nearby galaxies in the Local Supercluster, which drowns out the
+small cosmological imprint. Here we report the first detection of the expected
+dipole anisotropy in the galaxy distribution, in a survey of galaxies detected
+in radio waves. Radio galaxies are mostly located at cosmological distances, so
+the contamination from nearby clusters should be small. With local radio
+sources removed, we find a dipole anisotropy in the radio galaxy distribution
+in the same direction as the CMB, close to the expected amplitude. This result
+is confirmation of the standard cosmological interpretation of the CMB.",0203385v1
+2002-07-29,CMB-Normalized Predictions for Sunyaev-Zel'dovich effect fluctuations,"We predict the level of small-scale anisotropy in the cosmic microwave
+background (CMB) due to the Sunyaev--Zel'dovich (SZ) effect for the ensemble of
+cosmological models that are consistent with current measurements of
+large-scale CMB anisotropy. We argue that the recently reported detections of
+the small-scale (arcminutes) CMB anisotropy are only marginally consistent with
+being the SZ effect when cosmological models are calibrated to the existing
+primary CMB data on large scales. The discrepancy is at more than 2-2.5 sigma,
+and is mainly due to a lower sigma_8 <0.8 favored by the primary CMB and a
+higher sigma_8 > 1 favored by the SZ effect. A degeneracy between the optical
+depth to Thomson scattering and the CMB-derived value of sigma_8 suggests that
+the discrepancy is reduced if the universe was reionized very early, at a
+redshift of about 25.",0207633v1
+2002-08-16,Weak Lensing of the CMB: Cumulants of the Probability Distribution Function,"We discuss the real-space moments of temperature anisotropies in the cosmic
+microwave background (CMB) due to weak gravitational lensing by intervening
+large-scale structure. We show that if the probability distribution function of
+primordial temperature anisotropies is Gaussian, then it remains unchanged
+after gravitational lensing. With finite resolution, however, non-zero
+higher-order cumulants are generated both by lensing autocorrelations and by
+cross-correlations between the lensing potential and secondary anisotropies in
+the CMB such as the Sunayev-Zel'dovich (SZ) effect. Skewness is produced by
+these lensing-SZ correlations, while kurtosis receives contributions from both
+lensing alone and lensing-SZ correlations. We show that if the projected
+lensing potential is Gaussian, all cumulants of higher-order than the kurtosis
+vanish. While recent results raise the possibility of detection of the skewness
+in upcoming data, the kurtosis will likely remain undetected.",0208325v1
+2002-09-11,Anisotropies of the Cosmic Microwave Background,"We review the present status of Cosmic Microwave Background (CMB) anisotropy
+observations and discuss the main related astrophysical issues, instrumental
+effects and data analysis techniques. We summarise the balloon-borne and
+ground-based experiments that, after COBE-DMR, yielded detection or significant
+upper limits to CMB fluctuations. A comparison of subsets of combined data
+indicates that the acoustic features observed today in the angular power
+spectrum are not dominated by undetected systematics. Pushing the accuracy of
+CMB anisotropy measurements to their ultimate limits represents one of the best
+opportunities for cosmology to develop into a precision science in the next
+decade. We discuss the forthcoming sub-orbital and space programs, as well as
+future prospects of CMB observations.",0209215v2
+2002-09-26,Anisotropy at the end of the cosmic ray spectrum?,"The starburst galaxies M82 and NGC253 have been proposed as the primary
+sources of cosmic rays with energies above $10^{18.7}$ eV. For energies $\agt
+10^{20.3}$ eV the model predicts strong anisotropies. We calculate the
+probabilities that the latter can be due to chance occurrence. For the highest
+energy cosmic ray events in this energy region, we find that the observed
+directionality has less than 1% probability of occurring due to random
+fluctuations. Moreover, during the first 5 years of operation at Auger, the
+observation of even half the predicted anisotropy has a probability of less
+than $10^{-5}$ to occur by chance fluctuation. Thus, this model can be subject
+to test at very small cost to the Auger priors budget and, whatever the outcome
+of that test, valuable information on the Galactic magnetic field will be
+obtained.",0209546v3
+2002-11-07,Dipole anisotropies of IRAS galaxies and the contribution of a large-scale local void,"Recent observations of dipole anisotropies show that the velocity of the
+Local Group ($\Vec v_{\rm G}$) induced by the clustering of IRAS galax ies has
+an amplitude and direction similar to those of the velocity of Cosmic Microwave
+Background dipole anisotropy ($\Vec v_{\rm CMB}$), but the difference $| \Vec
+v_{\rm G} - \Vec v_{\rm CMB} |$ is still $\sim 170$ km/s, which is about 28% of
+$|\Vec v_{\rm CMB} |$. Here we consider the possibility that the origin of this
+difference comes from a hypothetical large-scale local void, with which we can
+account for the accelerating behavior of type Ia supernovae due to the spatial
+inhomogeneity of the Hubble constant without dark energies and derive the
+constraint to the model parameters of the local void. It is found as a result
+that the distance between the Local Group and the center of the void must be
+$(10 -- 20) h^{-1}$ Mpc, whose accurate value depends on the background model
+parameters.",0211137v2
+2003-06-18,The Wilkinson Microwave Anisotropy Probe,"The Wilkinson Microwave Anisotropy Probe (WMAP) has mapped the full sky in
+five frequency bands between 23 and 94 GHz. The primary goal of the mission is
+to produce high-fidelity, all-sky, polarization-sensitive maps that can be used
+to study the cosmic microwave background. Systematic errors in the maps are
+constrained to new levels: using all-sky data, aspects of the anisotropy may
+confidently be probed to sub-microKelvin levels. We give a brief description of
+the instrument and an overview of the first results from an analysis of maps
+made with one year of data. The highlights are (1) the flat Lambda-CDM model
+fits the data remarkably well, whereas an Einstein-de Sitter model does not;
+(2) we see evidence of the birth of the first generation of stars at z ~ 20;
+(3) when the WMAP data are combined and compared with other cosmological
+probes, a cosmic consistency emerges: multiple different lines of inquiry lead
+to the same results.",0306381v1
+2003-07-31,Measuring Statistical isotropy of the CMB anisotropy,"The statistical expectation values of the temperature fluctuations of cosmic
+microwave background (CMB) are assumed to be preserved under rotations of the
+sky. This assumption of {\em statistical isotropy} (SI) of the CMB anisotropy
+should be observationally verified since detection of violation of SI could
+have profound implications for cosmology. We propose a set of measures,
+$\kappa_\ell$ ($\ell=1,2,3, ...$) for detecting violation of statistical
+isotropy in an observed CMB anisotropy sky map indicated by non zero
+$\kappa_\ell$. We define an estimator for the $\kappa_\ell$ spectrum and
+analytically compute its cosmic bias and cosmic variance. The results match
+those obtained by measuring $\kappa_\ell$ using simulated sky maps. Non-zero
+(bias corrected) $\kappa_\ell$ larger than the SI cosmic variance will imply
+violation of SI. The SI measure proposed in this paper is an appropriate
+statistics to investigate preliminary indication of SI violation in the
+recently released WMAP data.",0308001v2
+2003-12-04,Signature of HDM clustering at Planck angular scales,"We present the CMB anisotropy induced by the non-linear perturbations in the
+massive neutrino density associated to the non-linear gravitational clustering.
+We show that the non-linear time varying potential induced by the gravitational
+clustering process generates metric perturbations that affect the time
+evolution of the density fluctuations in all the components of the expanding
+Universe, leaving imprints on the CMB anisotropy power spectrum at subdegree
+angular scales. For a neutrino fraction in agreement with that indicated by the
+astroparticle and nuclear physics experiments and a cosmological accreting mass
+comparable with the mass of known clusters, we find that CMB anisotropy
+measurements with {\sc Planck} angular resolution and sensitivity possibly
+combined to other precise cosmological observations will allow the detection of
+the dynamical, linear and non-linear effects of the neutrino gravitational
+clustering.",0312123v1
+2003-12-05,Antimatter from the cosmological baryogenesis and the anisotropies and polarization of the CMB radiation,"We discuss the hypotheses that cosmological baryon asymmetry and entropy were
+produced in the early Universe by phase transition of the scalar fields in the
+framework of spontaneous baryogenesis scenario. We show that annihilation of
+the matter-antimatter clouds during the cosmological hydrogen recombination
+could distort of the CMB anisotropies and polarization by delay of the
+recombination. After recombination the annihilation of the antibaryonic clouds
+(ABC) and baryonic matter can produce peak-like reionization at the high
+redshifts before formation of quasars and early galaxy formation. We discuss
+the constraints on the parameters of spontaneous baryogenesis scenario by the
+recent WMAP CMB anisotropy and polarization data and on possible manifestation
+of the antimatter clouds in the upcoming PLANCK data.",0312168v2
+2004-01-08,"CMB Anisotropies, Cosmological Parameters and Fundamental Physics: Current Status & Perspectives","I describe briefly the Cosmic Microwave Background (hereafter CMB) physics
+which explains why high accuracy observations of its spatial structure are a
+unique observational tool both for the determination of the global cosmological
+parameters and to constrain observationally the physics of the early universe.
+I also briefly survey the many experiments which have measured the anisotropies
+of the CMB and led to crucial advances in observational Cosmology. The somewhat
+frantic series of new results has recently culminated with the outcome of the
+WMAP satellite which confirmed earlier results, set new standards of accuracy,
+and suggested that the Universe may have reionised earlier than anticipated.
+Many more CMB experiments are currently taking data or being planned, with the
+Planck satellite on the 2007 Horizon poised to extract all the cosmological
+information in the temperature anisotropies, and foray deeply into
+polarisation.",0401108v1
+2004-02-24,Maps of the Cosmos: The Cosmic Microwave Background,"Since the IAU XXIV meeting in 2000, the CMB anisotropy has matured from being
+one of a number of cosmological probes to forming the bedrock foundation for
+what is now the standard model of cosmology. The large advances over the past
+three years have come from making better and better maps of the cosmos. We
+review the state of measurements of the anisotropy and outline some of what we
+have learned since 2000. The recent advancements may be placed roughly into
+three categories: 1) What we learn from the CMB with minimal input from other
+cosmic measurements such as the Hubble constant; 2) What we learn from the CMB
+in combination with other probes of large scale structure; and 3) What we learn
+by using the CMB as a back light. Future directions are also discussed. It is
+clear: we have much more to learn from the CMB anisotropy.",0402547v1
+2004-03-30,Looking for Cosmological Alfven Waves in WMAP Data,"A primordial cosmological magnetic field induces and supports vorticity or
+Alfven waves, which in turn generate cosmic microwave background (CMB)
+anisotropies. A homogeneous primordial magnetic field with fixed direction
+induces correlations between the $a_{l-1,m}$ and $a_{l+1,m}$ multipole
+coefficients of the CMB temperature anisotropy field. We discuss the
+constraints that can be placed on the strength of such a primordial magnetic
+field using CMB anisotropy data from the WMAP experiment. We place 3 $\sigma$
+upper limits on the strength of the magnetic field of $B < 15$ nG for vector
+perturbation spectral index $n=-5$ and $B<1.7$ nG for $n=-7$.",0403695v2
+2004-04-06,Study of Small-Scale Anisotropy of Ultrahigh Energy Cosmic Rays Observed in Stereo by HiRes,"The High Resolution Fly's Eye (HiRes) experiment is an air fluorescence
+detector which, operating in stereo mode, has a typical angular resolution of
+0.6 degrees and is sensitive to cosmic rays with energies above 10^18 eV. HiRes
+is thus an excellent instrument for the study of the arrival directions of
+ultrahigh energy cosmic rays. We present the results of a search for
+anisotropies in the distribution of arrival directions on small scales (<5
+degrees) and at the highest energies (>10^19 eV). The search is based on data
+recorded between 1999 December and 2004 January, with a total of 271 events
+above 10^19 eV. No small-scale anisotropy is found, and the strongest
+clustering found in the HiRes stereo data is consistent at the 52% level with
+the null hypothesis of isotropically distributed arrival directions.",0404137v2
+2004-04-21,Breaking the mass / anisotropy degeneracy in the Coma cluster,"We provide the first direct lifting of the mass/anisotropy degeneracy for a
+cluster of galaxies, by jointly fitting the line of sight velocity dispersion
+and kurtosis profiles of the Coma cluster, assuming an NFW tracer density
+profile, a generalized-NFW dark matter profile and a constant anisotropy
+profile. We find that the orbits in Coma must be quasi-isotropic, and find a
+mass consistent with previous analyses, but a concentration parameter 50%
+higher than expected in cosmological N-body simulations. We then test the
+accuracy of our method on realistic non-spherical systems with substructure and
+streaming motions, by applying it to the ten most massive structures in a
+cosmological N-body simulation. We find that our method yields fairly accurate
+results on average (within 20%), although with a wide variation (factor 1.7 at
+1 sigma) for the concentration parameter, with decreased accuracy and
+efficiency when the projected mean velocity is not constant with radius.",0404415v1
+2004-05-27,Stochastic Inflation and the Lower Multipoles in the CMB Anisotropies,"We generalize the treatment of inflationary perturbations to deal with the
+non-Markovian colored noise emerging from any realistic approach to stochastic
+inflation. We provide a calculation of the power-spectrum of the
+gauge-invariant comoving curvature perturbation to first order in the slow-roll
+parameters. Properly accounting for the constraint that our local patch of the
+Universe is homogeneous on scales just above the present Hubble radius, we find
+a blue tilt of the power-spectrum on the largest observable scales, in
+agreement with the WMAP data which show an unexpected suppression of the low
+multipoles of the CMB anisotropy. Our explanation of the anomalous behaviour of
+the lower multipoles of the CMB anisotropies does not invoke any ad-hoc
+introduction of new physical ingredients in the theory.",0405544v1
+2004-11-15,Cosmological reionization after WMAP: perspectives from PLANCK and future CMB missions,"The WMAP first year detection of a high redshift reionization through its
+imprints on CMB anisotropy T and TE mode angular power spectra calls for a
+better comprehension of the universe ionization and thermal history after the
+standard recombination. Different reionization mechanisms predict different
+signatures in the CMB, both in temperature and polarization anisotropies and in
+spectral distortions. The Planck capability to distinguish among different
+scenarios through its sensitivity to T, TE, and E mode angular power spectra is
+discussed. Perspectives open by future high sensitivity experiments on the CMB
+polarization anisotropy and spectrum are also presented.",0411415v1
+2004-11-16,A universal density slope - velocity anisotropy relation for relaxed structures,"We identify a universal relation between the radial density slope \alpha (r)
+and the velocity anisotropy \beta (r) for equilibrated structures. This
+relation holds for a variety of systems, including disk galaxy mergers,
+spherical collapses, cold dark matter (CDM) halos both with and without
+cooling. We argue that the shape of the relation is reasonable from fundamental
+principles when the dark matter or stars are assumed to obey Tsallis
+statistics, and in that case we fit the \alpha - \beta relation with just one
+free parameter. One can use this result to close the Jeans equations, for
+example to construct mass models of elliptical galaxies from observational data
+or to tune dark matter direct detection experiments. We also predict the
+asymptotic central slope and anisotropy of CDM halos to be approximately -1 and
+0.",0411473v3
+2004-12-21,CMB Anisotropy of the Poincare Dodecahedron,"We analyse the anisotropy of the cosmic microwave background (CMB) for the
+Poincare dodecahedron which is an example for a multi-connected spherical
+universe. We compare the temperature correlation function and the angular power
+spectrum for the Poincare dodecahedral universe with the first-year WMAP data
+and find that this multi-connected universe can explain the surprisingly low
+CMB anisotropy on large scales found by WMAP provided that the total energy
+density parameter Omega_tot is in the range 1.016...1.020. The ensemble average
+over the primordial perturbations is assumed to be the scale-invariant
+Harrison-Zel'dovich spectrum. The circles-in-the-sky signature is studied and
+it is found that the signal of the six pairs of matched circles could be missed
+by current analyses of CMB sky maps.",0412569v2
+2005-01-31,Relativistic second-order perturbations of nonzero-Λflat cosmological models and CMB anisotropies,"First the second-order perturbations of nonzero-\Lambda cosmological models
+are derived with an arbitrary potential function of spatial coordinates, using
+the nonlinear version of Lifshitz's method in the synchronous gauge. Their
+expression is the generalization (to the nonzero-\Lambda case) of second-order
+perturbations in the Einstein-de Sitter model which were derived previously by
+the present author. Next the second-order temperature anisotropies of Cosmic
+Micriwave Background radiation are derived using the gauge-invariant formula
+which was given by Mollerach and Matarrese. Moreover the corresponding
+perturbations in the Poisson gauge are derived using the second-order gauge
+transformations formulated by Bruni et al. In the second-order it is found in
+spite of gauges that tensor (gravitational-wave) perturbations and vector
+(shear) perturbations without vorticity are induced from the first-order scalar
+perturbations. These results will be useful to analyze the nonlinear effect of
+local inhomogeneities on Cosmic Microwave Background anisotropies.",0501663v4
+2005-03-02,On the Spectrum of Magnetohydrodynamic Turbulence,"We propose a phenomenological model for incompressible magnetohydrodynamic
+turbulence. We argue that nonlinear-wave interaction weakens as the energy
+cascade proceeds to small scales, however, the anisotropy of fluctuations along
+the large-scale magnetic field increases, which makes turbulence strong at all
+scales. To explain the weakening of the interaction, we propose that
+small-scale fluctuations of the velocity and magnetic fields become
+increasingly dynamically aligned as their scale decreases, so that turbulent
+eddies become locally anisotropic in the plane perpendicular to the large-scale
+magnetic field. In the limit of weak anisotropy, that is, weak large-scale
+magnetic field, our model reproduces the Goldreich-Sridhar spectrum, while the
+limit of strong anisotropy, that is, strong large-scale magnetic field,
+corresponds to the Iroshnikov-Kraichnan scaling of the spectrum. This is in
+good agreement with recent numerical results.",0503053v2
+2005-03-04,Elliptic CMB Sky,"The ellipticity of the anisotropy spots of the Cosmic Microwave Background
+measured by the Wilkinson Microwave Anisotropy Probe (WMAP) has been studied.
+We find an average ellipticity of about 2, confirming with a far larger
+statistics similar results found first for the COBE-DMR CMB maps, and then for
+the BOOMERanG CMB maps. There are no preferred directions for the obliquity of
+the anisotropy spots. The average ellipticity is independent of temperature
+threshold and is present on scales both smaller and larger than the horizon at
+the last scattering. The measured ellipticity characteristics are consistent
+with being the effect of geodesics mixing occurring in an hyperbolic Universe,
+and can mark the emergence of CMB ellipticity as a new observable constant
+describing the Universe. There is no way of simulating this effect. Therefore
+we cannot exclude that the observed behavior of the measured ellipticity can
+result from a trivial topology in the popular flat $\Lambda$-CDM model, or from
+a non-trivial topology.",0503103v2
+2005-03-31,Effects of Cosmological Magnetic Helicity on the Cosmic Microwave Background,"Cosmological magnetic fields induce temperature and polarization fluctuations
+in the cosmic microwave background (CMB) radiation. A cosmological magnetic
+field with current amplitude of order $10^{-9}$ G is detectable via
+observations of CMB anisotropies. This magnetic field (with or without
+helicity) generates vector perturbations through vortical motions of the
+primordial plasma. This paper shows that magnetic field helicity induces
+parity-odd cross correlations between CMB temperature and $B$-polarization
+fluctuations and between $E$- and $B$-polarization fluctuations, correlations
+which are zero for fields with no helicity (or for any parity-invariant
+source). Helical fields also contribute to parity-even temperature and
+polarization anisotropies, cancelling part of the contribution from the
+symmetric component of the magnetic field. We give analytic approximations for
+all CMB temperature and polarization anisotropy vector power spectra due to
+helical magnetic fields. These power spectra offer a method for detecting
+cosmological helical magnetic fields, particularly when combined with Faraday
+rotation measurements which are insensitive to helicity.",0503709v1
+2005-05-18,CMB Tomography: Reconstruction of Adiabatic Primordial Scalar Potential Using Temperature and Polarization Maps,"Assuming linearity of the perturbations at the time of decoupling, we
+reconstruct the primordial scalar potential from the temperature and
+polarization anisotropies in the cosmic microwave background radiation. In
+doing so we derive an optimal linear filter which, when operated on the
+spherical harmonic coefficients of the anisotropy maps, returns an estimate of
+the primordial scalar potential fluctuations in a spherical slice. The
+reconstruction is best in a thick shell around the decoupling epoch; the
+quality of the reconstruction depends on the redshift of the slice within this
+shell. With high quality maps of the temperature and polarization anisotropies
+it will be possible to obtain a reconstruction of potential fluctuation on
+scales between l=2 and l ~ 300 at the redshift of decoupling, with some
+information about the three-dimensional shapes of the perturbations in a shell
+of width 250Mpc.",0505386v1
+2005-06-17,Non-Gaussianity of Large-Scale Cosmic Microwave Background Anisotropies beyond Perturbation Theory,"We compute the fully non-linear Cosmic Microwave Background (CMB)
+anisotropies on scales larger than the horizon at last-scattering in terms of
+only the curvature perturbation, providing a generalization of the linear
+Sachs-Wolfe effect at any order in perturbation theory. We show how to compute
+the n-point connected correlation functions of the large-scale CMB anisotropies
+for generic primordial seeds provided by standard slow-roll inflation as well
+as the curvaton and other scenarios for the generation of cosmological
+perturbations. As an application of our formalism, we compute the three- and
+four-point connected correlation functions whose detection in future CMB
+experiments might be used to assess the level of primordial non-Gaussianity,
+giving the theoretical predictions for the parameters of quadratic and cubic
+non-linearities f_NL and g_NL.",0506410v2
+2005-08-13,Local virial relation and velocity anisotropy for collisionless self-gravitating systems,"The collisionless quasi-equilibrium state realized after the cold collapse of
+self-gravitating systems has two remarkable characters. One of them is the
+linear temperature-mass (TM) relation, which yields a characteristic
+non-Gaussian velocity distribution. Another is the local virial (LV) relation,
+the virial relation which holds even locally in collisionless systems through
+phase mixing such as cold-collapse. A family of polytropes are examined from a
+view point of these two characters. The LV relation imposes a strong constraint
+on these models: only polytropes with index $n \sim 5$ with a flat boundary
+condition at the center are compatible with the numerical results, except for
+the outer region. Using the analytic solutions based on the static and
+spherical Jeans equation, we show that this incompatibility in the outer region
+implies the important effect of anisotropy of velocity dispersion. Furthermore,
+the velocity anisotropy is essential in explaining various numerical results
+under the condition of the local virial relation.",0508308v2
+2005-09-18,Second-order gravitational effects of local inhomogeneities on CMB anisotropies and non-Gaussian signatures,"Based on the second-order nonlinear theory of perturbations in non-zero
+\Lambda flat cosmological models, we study the gravitational effects of local
+inhomogeneities on cosmic microwave background (CMB) anisotropies. As the local
+inhomogeneities we consider firstly large-scale dipole and quadruple
+distributions of galaxies around us and next an isolated cluster-scale matter
+distribution. It is found that, due to the second-order integral Sachs-Wolfe
+effect, the north-south asymmetry of CMB anisotropies and non-Gaussian
+signatures (in terms of scale-dependent estimators of kurtosis) in a spot-like
+object are caused from these matter distributions along light paths. Our
+theoretical results seem to be consistent with recent various observational
+results which have been shown by Hansen et al., Eriksen et al., Vielva et al.
+and Cruz et al.",0509518v4
+2005-10-25,Anisotropic k-essence cosmologies,"We investigate a Bianchi type-I (BTI) cosmology with k essence and find the
+set of models which dissipate the initial anisotropy. There are cosmological
+models with extended tachyon fields and k essence having constant bariotropic
+index. We obtain the conditions leading to a regular bounce of the average
+geometry and the residual anisotropy on the bounce. For constant potential, we
+develop purely kinetic k-essence models which are dust dominated in their early
+stages, dissipate the initial anisotropy and end in a stable de Sitter
+accelerated expansion scenario. We show that linear k field and polynomial
+kinetic function models evolve asymptotically to Friedmann-Robertson-Walker
+(FRW) cosmologies. The linear case is compatible with an asymptotic potential
+interpolating between $V_l\propto \phi^{-\gamma_l}$, in the shear dominated
+regime, and $V_l\propto\phi^{-2}$ at late time. In the polynomial case, the
+general solution contains cosmological models with an oscillatory average
+geometry. For linear k essence, we find the general solution in the BTI
+cosmology when the k field is driven by an inverse square potential. This model
+shares the same geometry than a quintessence field driven by an exponential
+potential.",0510726v2
+2005-12-16,On the Viability of Bianchi Type VIIh Models with Dark Energy,"We generalize the predictions for the CMB anisotropy patterns arising in
+Bianchi type VIIh universes to include a dark energy component. We consider
+these models in light of the result of Jaffe et al. (2005a,b) in which a
+correlation was found on large angular scales between the WMAP data and the
+anisotropy structure in a low density Bianchi universe. We find that by
+including a term Omega_L > 0, the same best-fit anisotropy pattern is
+reproduced by several combinations of cosmological parameters. This sub-set of
+models can then be further constrained by current observations that limit the
+values of various cosmological parameters. In particular, we consider the
+so-called geometric degeneracy in these parameters imposed by the peak
+structure of the WMAP data itself. Apparently, despite the additional freedom
+allowed by the dark energy component, the modified Bianchi models are ruled out
+at high significance.",0512433v1
+2006-02-22,Local Voids as the Origin of Large-angle Cosmic Microwave Background Anomalies I,"We explore the large angular scale temperature anisotropies in the cosmic
+microwave background due to expanding homogeneous local voids at redshift z~1.
+A compensated spherically symmetric homogeneous dust-filled void with radius
+\~3*10^2 h^{-1}Mpc, and density contrast ~-0.3 can be observed as a cold spot
+with a temperature anisotropy -1*10^{-5} surrounded by a slightly hotter ring.
+We find that a pair of these circular cold spots separated by ~50 degree can
+account both for the planarity of the octopole and for the alignment between
+the quadrupole and the octopole in the cosmic microwave background (CMB)
+anisotropy. The cold spot in the Galactic southern hemisphere which is
+anomalous at the ~3sigma level can be explained by such a large void at z~1.
+The observed north-south asymmetry in the large-angle CMB power can be
+attributed to the asymmetric distribution of these local voids between the two
+hemispheres. The statistical significance of the low quadrupole is further
+reduced in this interpretation of the large angular scale CMB anomalies.",0602478v2
+2006-04-13,Quantum noise and large-scale cosmic microwave background anisotropy,"We propose a new source for the cosmological density perturbation which is
+passive fluctuations of the inflaton driven dynamically by a colored quantum
+noise as a result of its coupling to other massive quantum fields. The created
+fluctuations grow with time during inflation before horizon-crossing. However,
+the larger-scale modes cross out the horizon earlier, thus resulting in a
+suppression of their density perturbation as compared with those on small
+scales. By using current observed CMB data to constrain the parameters
+introudced, we find that a significant contribution from the noise-driven
+perturbation to the density perturbation is still allowed. It in turn gives
+rise to a suppression of the large-scale CMB anisotropy that may be relevant to
+the observed low quadrupole in the WMAP CMB anisotropy data. We also briefly
+discuss the implications to the energy scale of inflation and the spectral
+index and non-Gaussianity of the density perturbation.",0604292v3
+2006-04-19,CMB Anisotropies at Second Order I,"We present the computation of the full system of Boltzmann equations at
+second-order describing the evolution of the photon, baryon and cold dark
+matter fluids. These equations allow to follow the time evolution of the Cosmic
+Microwave Background (CMB) anisotropies at second-order at all angular scales
+from the early epoch, when the cosmological perturbations were generated, to
+the present through the recombination era. This paper sets the stage for the
+computation of the full second-order radiation transfer function at all scales
+and for a a generic set of initial conditions specifying the level of
+primordial non-Gaussianity. In a companion paper, we will present the
+computation of the three-point correlation function at recombination which is
+so relevant for the issue of non-Gaussianity in the CMB anisotropies.",0604416v4
+2006-09-29,Impact of three years of data from the Wilkinson Microwave Anisotropy Probe on cosmological models with dynamical dark energy,"The first three years of observation of the Wilkinson Microwave Anisotropy
+Probe (WMAP) have provided the most precise data on the anisotropies of the
+cosmic microwave background (CMB) to date. We investigate the impact of these
+results and their combination with data from other astrophysical probes on
+cosmological models with a dynamical dark energy component. By considering a
+wide range of such models, we find that the constraints on dynamical dark
+energy are significantly improved compared to the first year data.",0609814v2
+2006-10-09,21-cm Background Anisotropies Can Discern Primordial Non-Gaussianity,"The non-Gaussianity of initial perturbations provides information on the
+mechanism that generated primordial density fluctuations. The expected
+non-Gaussianity for slow-roll inflationary models is well below the ultimate
+detection level with cosmic microwave background (CMB) anisotropies or
+large-large structure at low redshifts. We find that 21-cm background
+anisotropies of the low-frequency radio sky due to inhomogeneous neutral
+Hydrogen distribution at redshifts between 30 and 100 captures information on
+primordial non-Gaussianity better than any other cosmological probe. An all-sky
+21-cm experiment over the frequency range from 14 MHz to 40 MHz using a
+bandwidth of 1 MHz and with angular information out to a multipole of 10^5 can
+limit the primordial non-Gaussianity parameter f_nl < 0.01. The 21-cm
+background should eventually reveal the non-Gaussianity associated with single
+field slow-roll inflation.",0610257v2
+2006-12-22,The Validity of the Cosmic String Pattern Search with the Cosmic Microwave Background,"We introduce a new technique to detect the discrete temperature steps that
+cosmic strings might have left in the cosmic microwave background (CMB)
+anisotropy map. The technique provides a validity test on the pattern search of
+cosmic strings that could serve as the groundwork for future pattern searches.
+The detecting power of the technique is only constrained by two unavoidable
+features of CMB data: (1) the finite pixelization of the sky map and (2) the
+Gaussian fluctuation from instrumental noise and primordial anisotropy. We set
+the upper limit on the cosmic string parameter as $G\mu\lesssim 3.7\times
+10^{-6}$ at the 95% confidence level (CL) and find that the amplitude of the
+temperature step has to be greater than $44\mu K$ in order to be detected for
+the {\it{Wilkinson Microwave Anisotropy Probe (WMAP)}} 3 year data.",0612706v3
+2007-03-08,Effect of nearby supernova remnants on local Cosmic-Rays,"We study in detail the effect of different particle release times from
+sources on the cosmic-ray (CR) spectrum below $10^{15}eV$ in the Galaxy. We
+discuss different possible forms of particle injection such as burst-like
+injection, continuous injection for a finite time, injection from a stationary
+source and energy dependent injection. When applied to the nearby known
+supernova remnants, we find that the observed CR anisotropy data favour the
+burst-like particle injection model for the CR diffusion coefficient
+$D(E)\propto E^a$ with $a=0.3-0.6$ in the local region. In the study we have
+also found that the contribution of the sources G114.3+0.3 and Monogem dominate
+if the observed anisotropy is a result of the effect of the nearby sources.
+Further study shows that we should not neglect the contribution of the
+undetected old sources to the local CR anisotropy.",0703176v2
+1993-05-28,Cluster Variation Approach to the Random-Anisotropy Blume-Emery-Griffiths Model,"The random--anisotropy Blume--Emery--Griffiths model, which has been proposed
+to describe the critical behavior of $^3$He--$^4$He mixtures in a porous
+medium, is studied in the pair approximation of the cluster variation method
+extended to disordered systems. Several new features, with respect to mean
+field theory, are found, including a rich ground state, a nonzero percolation
+threshold, a reentrant coexistence curve and a miscibility gap on the high
+$^3$He concentration side down to zero temperature. Furthermore, nearest
+neighbor correlations are introduced in the random distribution of the
+anisotropy, which are shown to be responsible for the raising of the critical
+temperature with respect to the pure and uncorrelated random cases and
+contribute to the detachment of the coexistence curve from the $\lambda$ line.",9305036v1
+1994-01-31,Comment on `Anomalously Large Gap Anisotropy in the a-b Plane of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$',"Comment on `Anomalously Large Gap Anisotropy in the a-b Plane of Bi$_{{\bf
+2}}$Sr$_{{\bf 2}}$CaCu$_{{\bf 2}}$O$_{{\bf 8+}{\delta}}$', Kazumasa Miyake and
+Osamu Narikiyo, In a recent Letter, Shen and collaborators [Phys. Rev. Lett.
+{\bf 70}, 1555 (1993)] reported that angle-resolved photoemission spectra
+(ARPES) in Bi-2212 cuprate superconductor far below $T_{{\rm c}}$ has
+anomalously large anisotropy and then concluded that the symmetry of Cooper
+pair is likely to be $d_{x^{2}-y^{2}}$, i.e., $\Delta_{{\bf k}}=\Delta(\cos
+k_{x}a-\cos k_{y}a)$. In this Comment we point out that the interpretation done
+by Shen {\it et al\/.}, where the shift of edge near Fermi level has been
+identified with the gap $\Delta_{{\bf k}}$, is not unambiguous, and that a
+possibility of $d_{xy}$ pairing, i.e., $\Delta_{{\bf k}}=2\Delta\sin k_{x}a\sin
+k_{y}a$, cannot be ruled out.",9401073v1
+1994-08-19,Spin Softening in Models with Competing Interactions: A New High Anisotropy Expansion to All Orders,"An expansion in inverse spin anisotropy, which enables us to study the
+behaviour of discrete spin models as the spins soften, is developed. In
+particular we focus on models, such as the chiral clock model and the $p$-state
+clock model with competing first and second neighbour interactions, where there
+are special multiphase points at zero temperature at which an infinite number
+of ground states are degenerate. The expansion allows calculation of the ground
+state phase diagram near these points as the spin anisotropy, which constrains
+the spin to take discrete values, is reduced from infinity. Several different
+behaviours are found, from a single first order phase boundary to infinite
+series of commensurate phases.",9408053v1
+1995-01-14,Temperature dependent gap anisotropy in Bi$_{2}$Sr$_{2}$CaCu$_{2}$ O$_{8+x}$ as evidence for a mixed-symmetry ground state,"In a recent experiment, Ma et al. measured the temperature dependence of the
+gap anisotropy of oxygen-annealed Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$. Their
+measurements were taken along the two directions $\Gamma - M$ and $\Gamma - X$.
+They found that the gap along both directions is nonzero at low temperatures
+and that the ratio is strongly temperature dependent. We show, using
+Ginzburg-Landau theory, that this behavior can be obtained if one assumes the
+existence of s-wave and d-wave components for the order parameter. Our theory
+predicts orthorhombic anisotropy in the gap and anomalous behavior for the
+electronic specific heat below T$_c$.",9501057v1
+1995-03-18,Effects of Magnetic Order on the Upper Critical Field of UPt$_3$,"I present a Ginzburg-Landau theory for hexagonal oscillations of the upper
+critical field of UPt$_3$ near $T_c$. The model is based on a $2D$
+representation for the superconducting order parameter,
+$\vec{\eta}=(\eta_1,\eta_2)$, coupled to an in-plane AFM order parameter,
+$\vec{m}_s$. Hexagonal anisotropy of $H_{c2}$ arises from the weak in-plane
+anisotropy energy of the AFM state and the coupling of the superconducting
+order parameter to the staggered field. The model explains the important
+features of the observed hexagonal anisotropy [N. Keller, {\it et al.}, Phys.
+Rev. Lett. {\bf 73}, 2364 (1994).] including: (i) the small magnitude, (ii)
+persistence of the oscillations for $T\rightarrow T_c$, and (iii) the change in
+sign of the oscillations for $T> T^{*}$ and $T< T^{*}$ (the temperature at the
+tetracritical point). I also show that there is a low-field crossover
+(observable only very near $T_c$) below which the oscillations should vanish.",9503105v1
+1995-06-29,Modulated structures stabilised by spin softening: an expansion in inverse spin anisotropy,"We develop an analytic approach which allows us to study the behaviour of
+spin models with competing interactions and $p$-fold spin anisotropy, $D$, in
+the limit where the pinning potential which results from $D$ is large. This is
+an expansion in inverse spin anisotropy which must be carried out to all orders
+where necessary. Interesting behaviour occurs near where the boundary between
+different ground states is infinitely degenerate for infinite $D$. Here as $D$
+decreases and the spins are allowed to soften, we are able to demonstrate the
+existence of several different behaviours ranging from a single first-order
+boundary to infinite series of commensurate phases. The method is illustrated
+by considering the soft chiral clock model and the soft clock model with first-
+and second-neighbour competing interactions. In the latter case the results are
+strongly dependent on the value of $p$.",9506135v1
+1995-10-20,"Critical Properties of the transition between the Haldane phase and the large-D phase of the spin-1/2 ferromagnetic-antiferromagnetic Heisenberg chain with on-site anisotropy""","We analytically study the ground-state quantum phase transition between the
+Haldane phase and the large-$D$ (LD) phase of the $S=1/2$
+ferromagnetic-antiferromagnetic alternating Heisenberg chain with on-site
+anisotropy. We transform this model into a generalized version of the
+alternating antiferromagnetic Heisenberg model with anisotropy. In the
+transformed model, the competition between the transverse and longitudinal bond
+alternations yields the Haldane-LD transition. Using the bosonization method,
+we show that the critical exponents vary continuously on the Haldane-LD
+boundary. Our scaling relations between critical exponents very well explains
+the numerical results by Hida.",9510115v2
+1996-01-17,On the low temperature properties and specific anisotropy of pure anisotropically paired superconductors,"Dependences of low temperature behavior and anisotropy of various physical
+quantities for pure unconventional superconductors upon a particular form of
+momentum direction dependence for the superconducting order parameter (within
+the framework of the same symmetry type of superconducting pairing) are
+considered. A special attention is drawn to the possibility of different
+multiplicities of the nodes of the order parameter under their fixed positions
+on the Fermi surface, which are governed by symmetry. The problem of an
+unambiguous identification of a type of superconducting pairing on the basis of
+corresponding experimental results is discussed. Quasiparticle density of
+states at low energy for both homogeneous and mixed states, the low temperature
+dependences of the specific heat, penetration depth and thermal conductivity,
+the I-V curves of SS and NS tunnel junctions at low voltages are examined. A
+specific anisotropy of the boundary conditions for unconventional
+superconducting order parameter near $T_c$ for the case of specular reflection
+from the boundary is also investigated.",9601066v1
+1997-03-22,Internal Anisotropy of Collision Cascades,"We investigate the internal anisotropy of collision cascades arising from the
+branching structure. We show that the global fractal dimension cannot give an
+adequate description of the geometrical structure of cascades because it is
+insensitive to the internal anisotropy. In order to give a more elaborate
+description we introduce an angular correlation function, which takes into
+account the direction of the local growth of the branches of the cascades. It
+is demonstrated that the angular correlation function gives a quantitative
+description of the directionality and the interrelation of branches. The power
+law decay of the angular correlation is evidenced and characterized by an
+exponent and an angular correlation length different from the radius of
+gyration. It is demonstrated that the overlapping of subcascades has a strong
+effect on the angular correlation.",9703194v1
+1997-05-28,Effects of gap anisotropy upon the electronic structure around a superconducting vortex,"An isolated single vortex is considered within the framework of the
+quasiclassical theory. The local density of states around a vortex is
+calculated in a clean type II superconductor with an anisotropy. The anisotropy
+of a superconducting energy gap is crucial for bound states around a vortex. A
+characteristic structure of the local density of states, observed in the
+layered hexagonal superconductor 2H-NbSe2 by scanning tunneling microscopy
+(STM), is well reproduced if one assumes an anisotropic s-wave gap in the
+hexagonal plane. The local density of states (or the bound states) around the
+vortex is interpreted in terms of quasiparticle trajectories to facilitate an
+understanding of the rich electronic structure observed in STM experiments. It
+is pointed out that further fine structures and extra peaks in the local
+density of states should be observed by STM.",9705286v1
+1998-01-09,Dynamical Structure Factors of the Spin-1/2 XXZ Chain with Inverse-Square Exchange and Ising Anisotropy,"The dynamical properties of the S=1/2 antiferromagnetic XXZ chain are studied
+by the exact diagonalization and the recursion method of finite systems up to
+24 sites. Two types of the exchange interaction are considered: one is the
+nearest-neighbor type, and the other is the inverse-square one. As the Ising
+anisotropy becomes larger, there appears a noticeable difference in the
+transverse component S^{xx}(q,\omega) between the two types of the exchange.
+For the nearest-neighbor type, the peak frequency of S^{xx}(q,\omega) for each
+q approaches the center of the continuum spectrum. On the contrary, the peak
+frequency for the inverse-square type moves to the upper edge of the continuum,
+and separates from the continuum for the anisotropy larger than the threshold
+value. Whether the interaction between domain walls (solitons) is absent or
+repulsive in the Ising limit leads to this difference in the behavior of
+S^{xx}(q,\omega). In the longitudinal component S^{zz}(q,\omega), on the other
+hand, the feature of the dynamics is scarcely different between the two types.
+The energy gap and the static properties are also discussed.",9801070v1
+1998-01-26,Charge screening and magnetic anisotropy in metallic rare-earth systems,"The calculation of magnetic anisotropy constants is performed beyond the
+point charge model for a continuous charge density distribution of screening
+conduction electrons. An important role of the non-uniform electron density, in
+particular, of the Friedel oscillations, in the formation of crystal field is
+demonstrated. Such effects can modify strongly the effective ion (impurity)
+charge and even change its sign. This enables one to justify the anion model,
+which is often used at discussing experimental data on hydrogen-containing
+systems. Possible applications to the pure rare-earth metals and RCo5 compounds
+are discussed. The deformation of magnetic structure near the interstitial
+positive muon owing to the strong local anisotropy, and the corresponding
+contribution to the dipole field at the muon are considered.",9801269v1
+1998-02-03,The Anisotropic Bak-Sneppen Model,"The Bak-Sneppen model is shown to fall into a different universality class
+with the introduction of a preferred direction, mirroring the situation in spin
+systems. This is first demonstrated by numerical simulations and subsequently
+confirmed by analysis of the multi-trait version of the model, which admits
+exact solutions in the extremes of zero and maximal anisotropy. For
+intermediate anisotropies, we show that the spatiotemporal evolution of the
+avalanche has a power law ``tail'' which passes through the system for any
+non-zero anisotropy but remains fixed for the isotropic case, thus explaining
+the crossover in behaviour. Finally, we identify the maximally anisotropic
+model which is more tractable and yet more generally applicable than the
+isotropic system.",9802028v2
+1998-04-28,Ferromagnetism and Temperature-Driven Reorientation Transition in Thin Itinerant-Electron Films,"The temperature-driven reorientation transition which, up to now, has been
+studied by use of Heisenberg-type models only, is investigated within an
+itinerant-electron model. We consider the Hubbard model for a thin fcc(100)
+film together with the dipole interaction and a layer-dependent anisotropy
+field. The isotropic part of the model is treated by use of a generalization of
+the spectral-density approach to the film geometry. The magnetic properties of
+the film are investigated as a function of temperature and film thickness and
+are analyzed in detail with help of the spin- and layer-dependent quasiparticle
+density of states. By calculating the temperature dependence of the
+second-order anisotropy constants we find that both types of reorientation
+transitions, from out-of-plane to in-plane (``Fe-type'') and from in-plane to
+out-of-plane (``Ni-type'') magnetization are possible within our model. In the
+latter case the inclusion of a positive volume anisotropy is vital. The
+reorientation transition is mediated by a strong reduction of the surface
+magnetization with respect to the inner layers as a function of temperature and
+is found to depend significantly on the total band occupation.",9804301v1
+1998-06-16,Curie Temperature of Anisotropic Ferromagnetic Films,"Dimensional crossover of ordering in ferromagnetic films with both periodic
+and free boundary conditions is studied for the exactly solvable uniaxial model
+of classical D-component spin vectors in the limit D \to \infty. Analytical and
+numerical solution of the exact equations describing this model shows that for
+lattice dimensionalities d>4, finite-size corrections to the bulk values of T_c
+are characterized by the mean-field exponents and anisotropy-dependent
+amplitudes. For d =< 4, the mean-field behavior is only realized in the region
+\kappa_c N >> 1, where \kappa_c is the dimensionlesss inverse transverse (with
+respect to the easy axis) bulk correlation length at T_c and N is the number of
+layers in the film. In the region \kappa_c N << 1 and the dimensionality range
+3 < d =< 4, finite-size corrections are described by the universality class of
+the isotropic D=\infty model. For d =< 3, magnetic ordering vanishes in the
+isotropic limit, \kappa_c \to 0, since the film behaves as an object of
+dimensionality d'=d-1 =< 2 and long-wavelength fluctuations destroy the order.
+Here the suppression of T_c of a film can be substantial, depending on the
+competition between the weakening anisotropy and the increasing film thickness.
+For thick films, T_c becomes small only for very small anisotropy.",9806198v1
+1998-08-27,Thickness evolution of coercivity in ultrathin magnetic films,"The thickness evolution of in-plane magnetization reversal in ultrathin films
+is studied with a theoretical model that takes account of surface roughness
+typical of epitaxial growth. Guided by N\'{e}el's model, step edge sites of
+monolayer-height islands are assigned a two-fold anisotropy in addition to a
+four-fold anisotropy at all sites. Coercivity is found to depend essentially on
+both the film thickness and the partial coverage of the topmost layer. Its
+qualitative features are determined primarily by sample geometry and the size
+of the step anisotropy compared to the domain wall energy. Magnetostatic
+interactions change the results quantitatively, but not qualitatively. Their
+effect is understood by comparing calculations with and without their
+inclusion.",9808311v1
+1998-09-08,Inelastic Neutron Scattering Study of Mn_12-Acetate,"We report zero-field inelastic neutron scattering experiments on a deuterated
+powder sample of Mn12-Acetate consisting of a large number of nominally
+identical spin-10 magnetic clusters. Our resolution enables us to see a series
+of peaks corresponding to transitions between the anisotropy levels within the
+spin-10 manifold. A fit to the spin Hamiltonian yields an anisotropy constant
+D=0.54 K and a fourth-order diagonal anisotropy coefficient A = 1.2x10^-3 K.
+Performed in the absence of a magnetic field, our experiments do not involve
+the g-values as fitting parameters, thereby yielding particularly reliable
+values of D and A.",9809133v2
+1998-09-30,Effect of anisotropy on universal transport in unconventional superconductors,"We investigate the universal electronic transport for a mixed
+$d_{x^2-y^2}$+s-wave superconductor in the presence of an anisotropic
+elliptical Fermi surface. Similar to the universal low-temperature transport
+predicted in a $d_{x^2-y^2}$-wave superconductor with a circular Fermi surface,
+anisotropic universal features are found in the low-temperature microwave
+conductivity, and thermal conductivity in the anisotropic system. The effects
+of anisotropy on the penetration depth, impurity induced $T_c$ suppression, and
+the zero-frequency density of states are also considered. While a small amount
+of anisotropy can lead to a strong suppression of the effective scattering rate
+and hence the density of states at zero frequency, experimental data suggests
+that large effects are restored by a negative $s$-component gap admixture.",9809400v1
+1999-03-03,Theory of magnetoresistance in films of dilute magnetic alloys,"Earlier a magnetic anisotropy for magnetic impurities nearby the surface of
+non-magnetic host was proposed in order to explain the size dependence of the
+Kondo effect in dilute magnetic alloys. Recently Giordano has measured the
+magnetoresistance of dilute Au(Fe) films for different thicknesses well above
+the Kondo temperature $T_K$. In this way he verified the existence of that
+anisotropy even for such a case where the Kondo effect is not dominating. For
+detailed comparison of that suggestion with experiments, the magnetic field
+dependence of the magnetoresistance is calculated in the lowest approximation,
+thus in the second order of the exchange coupling. The strength of the
+anisotropy is very close to earlier estimates deduced from the size dependence
+of the Kondo resistivity amplitude.",9903054v2
+1999-03-05,Comment on ``Evidence for Anisotropic State of Two-Dimensional Electrons in High Landau Levels'',"In a recent letter M. Lilly et al [PRL 82, 394 (1999)] have shown that a
+highly anisotropic state can arise in certain two dimensional electron systems.
+In the large square samples studied, resistances measured in the two
+perpendicular directions are found to have a ratio that may be 60 or larger at
+low temperature and at certain magnetic fields. In Hall bar measurements, the
+anisotropy ratio is found to be much smaller (roughly 5). In this comment we
+resolve this discrepancy by noting that the anisotropy of the underlying sheet
+resistivities is correctly represented by Hall bar resistance measurements but
+shows up exponentially enhanced in resistance measurements on square samples
+due to simple geometric effects. We note, however, that the origin of this
+underlying resistivity anisotropy remains unknown, and is not addressed here.",9903086v3
+1999-03-16,Opening of the Haldane Gap in Anisotropic Two- and Four-Leg Spin Ladders,"We study the opening of the Haldane gap in two-leg and four-leg anisotropic
+spin ladders using bosonization and renormalization group methods, and we
+determine the phase diagram as a function of the interchain coupling and the
+relative anisotropy. It is found that the opening of the Haldane gap is
+qualitatively different for the two cases considered. For the two-leg ladder
+the Haldane gap opens for arbitrarily small interchain coupling, independent of
+the relative anisotropy, and the Haldane phase exists in a large region of
+parameter space. For the four-leg ladder the opening of the Haldane gap is
+strongly dependent on both the interchain coupling as well as the relative
+anisotropy, and the Haldane phase exists only in a narrow region about the
+isotropic antiferromagnet.",9903241v1
+1999-04-30,Magnetic excitations in charge- ordered NaV2O5,"An investigation of the spin excitation spectrum of charge ordered (CO)
+NaV2O5 is presented. We discuss several different exchange models which may be
+relevant for this compound, namely in- line and zig-zag chain models with weak
+as well as strong inter- chain coupling and also a ladder model and a CO/MV
+(mixed valent) model. We put special emphasis on the importance of large
+additional exchange across the diagonals of V- ladders and the presence of
+exchange anisotropies on the excitation spectrum. It is shown that the observed
+splitting of transverse dispersion branches may both be interpreted as
+anisotropy effect as well as acoustic- optic mode splitting in the weakly
+coupled chain models. In addition we calculate the field dependence of
+excitation modes in these models. Furthermore we show that for strong inter-
+chain coupling, as suggested by recent LDA+U results, an additional high energy
+optical excitation appears and the spin gap is determined by anisotropies. The
+most promising CO/MV model predicts a spin wave dispersion perpendicular to the
+chains which agrees very well with recent results obtained by inelastic neutron
+scattering.",9904443v2
+1999-07-08,Quasi-long-range order in the random anisotropy Heisenberg model: functional renormalization group in 4-εdimensions,"The large distance behaviors of the random field and random anisotropy O(N)
+models are studied with the functional renormalization group in 4-\epsilon
+dimensions. The random anisotropy Heisenberg (N=3) model is found to have a
+phase with the infinite correlation radius at low temperatures and weak
+disorder. The correlation function of the magnetization obeys a power law <
+m(x) m(y) >\sim |x-y|^{-0.62\epsilon}. The magnetic susceptibility diverges at
+low fields as \chi \sim H^{-1+0.15\epsilon}. In the random field O(N) model the
+correlation radius is found to be finite at the arbitrarily weak disorder for
+any N>3. The random field case is studied with a new simple method, based on a
+rigorous inequality. This approach allows one to avoid the integration of the
+functional renormalization group equations.",9907122v3
+1999-08-13,Resistive upper critical fields and irreversibility lines of optimally-doped high-T_c cuprates,"We present the resistively-determined upper critical field H^{\rho}_{c2}(T)
+and the irreversibility lines H^{\rho}_{irr}(T) of various high-T_c cuprates,
+deduced from measurements in 61-T pulsed magnetic fields applied parallel to
+the c-axis. The SHAPE of both H^{\rho}_{c2}(T) and H^{\rho}_{irr}(T) depends
+monotonically on the anisotropy of the material and none of the samples show
+saturation of H^{\rho}(T) at low temperatures. The anomalous positive
+curvature, d^2 H^{\rho}/dT^2 > 0, is the strongest in materials with the
+largest normal-state anisotropy, regardless of whether anisotropy is varied by
+changing the carrier concentration or by comparing a variety of optimally-doped
+compounds.",9908190v1
+1999-11-24,Random Field and Random Anisotropy Effects in Defect-Free Three-Dimensional XY Models,"Monte Carlo simulations have been used to study a vortex-free XY ferromagnet
+with a random field or a random anisotropy on simple cubic lattices. In the
+random field case, which can be related to a charge-density wave pinned by
+random point defects, it is found that long-range order is destroyed even for
+weak randomness. In the random anisotropy case, which can be related to a
+randomly pinned spin-density wave, the long-range order is not destroyed and
+the correlation length is finite. In both cases there are many local minima of
+the free energy separated by high entropy barriers. Our results for the random
+field case are consistent with the existence of a Bragg glass phase of the type
+discussed by Emig, Bogner and Nattermann.",9911398v2
+2000-03-27,Effects of interlayer coupling on the irreversibility lines of NbN/AlN superconducting multilayers,"We have studied the temperature dependence of the in-plane resistivity of
+NbN/AlN multilayer samples with varying insulating layer thickness in magnetic
+fields up to 7 Tesla parallel and perpendicular to the films. The upper
+critical field shows a crossover from 2D to 3D behavior in parallel fields. The
+irreversibility lines have the form (1-T/Tc)^alpha, where alpha varies from 4/3
+to 2 with increasing anisotropy. The results are consistent with simultaneous
+melting and decoupling transitions for low anisotropy sample, and with melting
+of decoupled pancakes in the superconducting layers for higher anisotropy
+samples.",0003426v2
+2000-05-25,Laplacian growth with separately controlled noise and anisotropy,"Conformal mapping models are used to study competition of noise and
+anisotropy in Laplacian growth. For that, a new family of models is introduced
+with the noise level and directional anisotropy controlled independently.
+Fractalization is observed in both anisotropic growth and the growth with
+varying noise. Fractal dimension is determined from cluster size scaling with
+its area. For isotropic growth we find d = 1.7, both at high and low noise. For
+anisotropic growth with reduced noise the dimension can be as low as d = 1.5
+and apparently is not universal. Also, we study fluctuations of particle areas
+and observe, in agreement with previous studies, that exceptionally large
+particles may appear during the growth, leading to pathologically irregular
+clusters. This difficulty is circumvented by using an acceptance window for
+particle areas.",0005456v2
+2000-06-14,Orientational pinning of quantum Hall striped phase,"In ultra-clean 2D electron systems on (001) GaAs/AlGaAs upon filling high
+Landau levels, it was recently observed a new class of collective states, which
+can be related to the spontaneous formation of a charge density wave (``striped
+phase''). We address to the following unsolved problem: what is the reason for
+stripe pinning along the crystallographic direction [110]? It is shown that in
+a single heterojunction (001) III-V the effective mass of 2D electrons is
+anisotropic. This natural anisotropy is due to the reduced (C_{2v}) symmetry of
+the heterojunction and, even being weak (0.1 percent), can govern the stripe
+direction. A magnetic field parallel to the interface induces ``magnetic''
+anisotropy of the effective mass. The competition of these two types of
+anisotropy provides quantitative description of the experiment.",0006226v1
+2000-07-18,Shape-induced magnetic anisotropy in dilute magnetic alloys,"We extend the theory of the surface-induced magnetic anisotropy to mesoscopic
+samples with arbitrary geometry. The shape-induced anisotropy of impurity spins
+in small brick-shaped grains of dilute magnetic alloys is studied in detail.
+The surface-induced blocking of a magnetic-impurity spin is shown to be very
+sensitive to geometric parameters of a grain. This implies that the apparent
+discrepancy between the experimental data of different groups on the size
+dependence of the Kondo resistivity can result from different microstructure of
+the used samples. In order to interpret recent experimental data on the
+anomalous Hall effect in thin polycrystalline Fe doped Au films, we analyse the
+magnetisation of impurity spins as a function of the impurity position and of
+the grain shape.",0007294v1
+2000-08-05,Reversed anisotropies and thermal contraction of FCC (110) surfaces,"The observed anisotropies of surface vibrations for unreconstructed FCC metal
+(110) surfaces are often reversed from the ""common sense"" expectation. The
+source of these reversals is investigated by performing ab initio density
+functional theory calculations to obtain the surface force constant tensors for
+Ag(110), Cu(110) and Al(110). The most striking result is a large enhancement
+in the coupling between the first and third layers of the relaxed surface,
+which strongly reduces the amplitude of out-of-plane vibrations of atoms in the
+first layer. This also provides a simple explanation for the thermal
+contraction of interlayer distances. Both the anisotropies and the thermal
+contraction arise primarily as a result of the bond topology, with all three
+(110) surfaces showing similar behavior.",0008088v1
+2000-09-04,Current Induced Magnetization Switching in Small Domains of Different Anisotropies,"Several recent experimental studies have confirmed the possibility of
+switching the magnetization direction in the small magnetic domains by pumping
+large spin-polarized currents through them. On the basis of equations proposed
+by J.Slonczewski for the case when magnetization of the domains is almost
+uniform, we analyze the stability and switching for two types of magnetic and
+shape anisotropies of a magnetic domain in a nanowire and find qualitatively
+different behavior, including different shapes of bistable regions. Our study
+is analytic as opposed to recent numeric work. Assumed anisotropies can be
+realized in experiments and our predictions can be used to experimentally test
+the theory of spin-transfer torques. Such test would be especially interesting
+since alternative approaches are discussed in the literature.",0009034v1
+2001-01-18,Thermodynamic perturbation theory for dipolar superparamagnets,"Thermodynamic perturbation theory is employed to derive analytical
+expressions for the equilibrium linear susceptibility and specific heat of
+lattices of anisotropic classical spins weakly coupled by the dipole-dipole
+interaction. The calculation is carried out to the second order in the coupling
+constant over the temperature, while the single-spin anisotropy is treated
+exactly. The temperature range of applicability of the results is, for weak
+anisotropy (A/kT << 1), similar to that of ordinary high-temperature
+expansions, but for moderately and strongly anisotropic spins (A/kT > 1) it can
+extend down to the temperatures where the superparamagnetic blocking takes
+place (A/kT \sim 25), provided only the interaction strength is weak enough.
+Besides, taking exactly the anisotropy into account, the results describe as
+particular cases the effects of the interactions on isotropic (A = 0) as well
+as strongly anisotropic (A \to \infty) systems (discrete orientation model and
+plane rotators).",0101287v2
+2001-02-28,Electronic and Optical Properties of Self-Assembled Quantum Wires,"We have studied the band and optical properties of self-assembled quantum
+wires. In particular, the band structures and optical matrix elements of
+strained multiple quantum-wires (QWR's) are investigated theoretically via the
+effective bond-orbital model(EBOM), which takes into account the effects of
+valence-band anisotropy and the band mixing. It is found that the strain leads
+to further confinement of carriers and enhancement of the anisotropy.
+  By using the EBOM and valence-force field model, we systematically studied
+the microstrain effects on the electronic and optical properties of
+Ga$_{1-x}$In$_x$As self-assembled quantum-wires (QWR's) made of short-period
+superlattices with strain-induced lateral ordering. Valence-band anisotropy,
+band mixing, and effects due to local strain distribution at the atomistic
+level are all taken into account.A comprehensive collection of different
+structures in our model are presented.
+  Finally, the excitonic absorption spectrum for the SILO quantum wires are
+investigated by using our envelope function model.",0102506v2
+2001-03-02,Superconducting Gap and Strong In-Plane Anisotropy in Untwinned YBa2Cu3O7-d,"With significantly improved sample quality and instrumental resolution, we
+clearly identify in the (pi,0) ARPES spectra from YBa2Cu3O6.993, in the
+superconducting state, the long-sought `peak-dip-hump' structure. This advance
+allows us to investigate the large a-b anisotropy of the in-plane electronic
+structure including, in particular, a 50% difference in the magnitude of the
+superconducting gap that scales with the energy position of the hump feature.
+This anisotropy, likely induced by the presence of the CuO chains, raises
+serious questions about attempts to quantitatively explain the YBa2Cu3O7-d data
+from various experiments using models based on a perfectly square lattice.",0103047v1
+2001-03-16,Gap Anisotropy and de Haas-van Alphen Effect in Type-II Superconductors,"We present a theoretical study on the de Haas-van Alphen (dHvA) oscillation
+in the vortex state of type-II superconductors, with a special focus on the
+connection between the gap anisotropy and the oscillation damping. Numerical
+calculations for three different gap structures clearly indicate that the
+average gap along extremal orbits is relevant for the magnitude of the extra
+damping, thereby providing a support for experimental efforts to probe gap
+anisotropy through the dHvA signal. We also derive an analytic formula for the
+extra damping which gives a good fit to the numerical results.",0103336v3
+2001-03-23,Transport and magnetic anisotropy in CMR thin film La_{1-x}Ca_{x}MnO_{3} (x \approx 1/3) induced by a film-substrate interaction,"We present a study of anisotropy of transport and magnetic properties in
+La_{1-x}Ca_{x}MnO_{3} (x \approx 1/3) film prepared by pulsed-laser deposition
+onto a LaAlO_{3} sunstrate. We found a non-monotonic dependence of
+magnetoresistance (MR) on magnetic field H for both H perpendicular and
+parallel to the film plane but perpendicular to the current. This rather
+complex behavior of MR manifests itself at low temperatures, far below the
+Curie temperature. Two main sources of MR anisotropy have been considered in
+the explanantion of the results: (1) the existence of preferential directions
+of magnetization (due to strains stemming from the lattice film-substrate
+mismatch or other reasons); (2) dependence of resistance on the angle between
+current and the magnetization, which is inherent in ferromagnets.",0103493v1
+2001-04-15,Nonlinear ac response of anisotropic composites,"When a suspension consisting of dielectric particles having nonlinear
+characteristics is subjected to a sinusoidal (ac) field, the electrical
+response will in general consist of ac fields at frequencies of the
+higher-order harmonics. These ac responses will also be anisotropic. In this
+work, a self-consistent formalism has been employed to compute the induced
+dipole moment for suspensions in which the suspended particles have nonlinear
+characteristics, in an attempt to investigate the anisotropy in the ac
+response. The results showed that the harmonics of the induced dipole moment
+and the local electric field are both increased as the anisotropy increases for
+the longitudinal field case, while the harmonics are decreased as the
+anisotropy increases for the transverse field case. These results are
+qualitatively understood with the spectral representation. Thus, by measuring
+the ac responses both parallel and perpendicular to the uniaxial anisotropic
+axis of the field-induced structures, it is possible to perform a real-time
+monitoring of the field-induced aggregation process.",0104270v1
+2001-04-25,Anisotropy of magnetothermal conductivity in Sr2RuO4,"The dependence of in-plane and interplane thermal conductivities of Sr2RuO4
+on temperature, as well as magnetic field strength and orientation, is
+reported. We found no notable anisotropy in the thermal conductivity for the
+magnetic field rotation parallel to the conducting plane in the whole range of
+experimental temperatures and fields, except in the vicinity of the upper
+critical field Hc2, where the anisotropy of the Hc2 itself plays a dominant
+role. This finding imposes strong constraints on the possible models of
+superconductivity in Sr2RuO4 and supports the existence of a superconducting
+gap with a line of nodes running orthogonal to the Fermi surface cylinder.",0104492v1
+2001-04-28,"Electronic anisotropy, magnetic field-temperature phase diagram and their dependence on resistivity in c-axis oriented MgB2 thin films","An important predicted, but so far uncharacterized, property of the new
+superconductor MgB2 is electronic anisotropy arising from its layered crystal
+structure. Here we report on three c-axis oriented thin films, showing that the
+upper critical field anisotropy ratio Hc2par/Hc2perp is 1.8 to 2.0, the ratio
+increasing with higher resistivity. Measurements of the magnetic
+field-temperature phase diagram show that flux pinning disappears at H* ~
+0.8Hc2perp(T) in untextured samples. Hc2par(0) is strongly enhanced by alloying
+to 39 T for the highest resistivity film, more than twice that seen in bulk
+samples.",0104562v1
+2001-05-21,Unusual magnetic susceptibility anisotropy in untwinned La_{2-x}Sr_xCuO_4 single crystals in the lightly-doped region,"We present a study of the magnetic susceptibility in carefully detwinned
+La_{2-x}Sr_{x}CuO_4 single crystals in the lightly-doped region (x=0-0.03),
+which demonstrates a remarkable in-plane anisotropy of the spin system. This
+anisotropy is found to persist after the long-range antiferromagnetic (AF)
+order is destroyed by hole doping, suggesting that doped holes break the AF
+order into domains in which the spin alignment is kept essentially intact. It
+turns out that the freezing of the spins taking place at low temperatures is
+also notably anisotropic, implying that the ""spin-glass"" feature is governed by
+the domain structure as well.",0105390v1
+2001-05-30,Anisotropy in the electronic screening of oxygen lattice modes in YBa(2)Cu(3)O(6.95),"Inelastic neutron scattering data from a twinned single-crystal of
+YBa2Cu3O6.95 are presented that show a distinct a-b plane anisotropy in the
+oxygen vibrations. The Cu-O bond-stretching type phonons are simultaneously
+observed along the a and b directions due to a 4 meV splitting arising from the
+orthorhombicity. The present results show the bond-stretching branch along b
+(parallel to the chain) has a continuous dispersion, while the branch along a
+is discontinuous, suggesting a possibility of short-range cell-doubling along
+a. Furthermore, the LO mode along a is split in en-ergy from its TO partner at
+non-zero q-vectors, while the b mode is not. These results imply strong
+anisotropy in the electronic screening and a one-dimensional character in
+underlying charge fluctuations.",0105593v1
+2001-06-12,Single ion anisotropy of Mn doped GaAs measured by EPR,"Electron paramagnetic resonance (EPR) study of MBE grown Mn doped GaAs is
+presented. The resolved fine structure allows us to evaluate the crystal field
+parameters of the spin Hamiltonian. The obtained cubic constant is a= -14.1
+10^-4/cm. The axial field parameter, D, increases with Mn concentration, x,
+i.e., with the strain of (Ga,Mn)As layers. Extrapolation of D shows that the
+single ion anisotropy is the important contribution to the magnetic anisotropy
+which is observed in ferromagnetic layers with greater Mn concentrations. The
+analysis of the EPR linewidth shows that native defects of the concentration of
+5 10^19/cm^3, but not the Mn ions, are the main origin of crystal field
+fluctuations.",0106227v1
+2001-06-27,A Distribution of Tunnel Splittings in Mn$_{12}$-Acetate,"In magnetic fields applied parallel to the anisotropy axis, the relaxation of
+the magnetization of Mn$_{12}$ measured for different sweep rates is shown to
+collapse onto a single scaled curve. The form of the scaling implies that the
+dominant symmetry-breaking process that gives rise to tunneling is a locally
+varying second-order anisotropy, forbidden by tetragonal symmetry in the
+perfect crystal, which gives rise to a broad distribution of tunnel splittings
+in a real crystal of Mn$_{12}$-acetate. Different forms applied to even and
+odd-numbered steps provide a distinction between even step resonances
+(associated with crystal anisotropy) and odd resonances (which require a
+transverse component of magnetic field).",0106579v3
+2001-08-10,Thermodynamics of Two Dimensional Magnetic Nanoparticles,"A two dimensional magnetic particle in the presence of an external magnetic
+field is studied. Equilibrium thermodynamical properties are derived by
+evaluating analytically the partition function. When the external field is
+applied perpendicular to the anisotropy axis the system exhibits a second order
+phase transition with order parameter being the magnetization parallel to the
+field. In this case the system is isomorph to a mechanical system consisting in
+a particle moving without friction in a circle rotating about its vertical
+diameter. Contrary to a paramagnetic particle, equilibrium magnetization shows
+a maximum at finite temperature. We also show that uniaxial anisotropy in a
+system of noninteracting particles can be missinterpreted as a ferromagnetic or
+antiferromagnetic coupling among the magnetic particles depending on the angle
+between anisotropy axis and magnetic field.",0108178v1
+2001-08-20,Enhancement of the magnetic anisotropy of nanometer-sized Co clusters: influence of the surface and of the inter-particle interactions,"We study the magnetic properties of spherical Co clusters with diameters
+between 0.8 nm and 5.4 nm (25 to 7500$ atoms) prepared by sequential sputtering
+of Co and Al2O3. The particle size distribution has been determined from the
+equilibrium susceptibility and magnetization data and it is compared to
+previous structural characterizations. The distribution of activation energies
+was independently obtained from a scaling plot of the ac susceptibility.
+Combining these two distributions we have accurately determined the effective
+anisotropy constant Keff. We find that Keff is enhanced with respect to the
+bulk value and that it is dominated by a strong anisotropy induced at the
+surface of the clusters. Interactions between the magnetic moments of adjacent
+layers are shown to increase the effective activation energy barrier for the
+reversal of the magnetic moments. Finally, this reversal is shown to proceed
+classically down to the lowest temperature investigated (1.8 K).",0108304v1
+2001-08-21,Quasiparticle spectrum of d-wave superconductors in the mixed state: a large Fermi-velocity anisotropy study,"The quasiparticle spectrum of a two-dimensional d-wave superconductor in the
+mixed state, H_c1 << H << H_c2, is studied for large values of the ``anisotropy
+ratio'' alpha_D = v_F/v_Delta. For a square vortex lattice rotated by 45
+degrees from the quasiparticle anisotropy axes (and the usual choice of
+Franz--Tesanovic singular gauge transformation) we determine essential features
+of the band structure asymptotically for large alpha_D, using an effective
+one-dimensional model, and compare them to numerical calculations. We find that
+several features of the band structure decay to zero exponentially fast for
+large alpha_D. Using a different choice of singular gauge transformation, we
+obtain a different band structure, but still find qualitative agreement between
+the 1D and full 2D calculations. Finally, we distort the square lattice into a
+non-Bravais lattice. Both the one- and two-dimensional numerical calculations
+of the energy spectra show a gap around zero-energy, with our gauge choice, and
+the two excitation spectra agree reasonably well.",0108324v1
+2001-10-11,Anisotropy of Vortex-Liquid and Vortex-Solid Phases in Single Crystals of Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$: Violation of the Scaling Law,"The vortex-liquid and vortex-solid phases in single crystals of
+Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ placed in tilted magnetic fields are studied
+by in-plane resistivity measurements using the Corbino geometry to avoid
+spurious surface barrier effects. It was found that the anisotropy of the
+vortex-solid phase increases with temperature and exhibits a maximum at
+$T\approx 0.97 T_c$. In contrast, the anisotropy of the vortex-liquid rises
+monotonically across the whole measured temperature range. The observed
+behavior is discussed in the context of dimensional crossover and thermal
+fluctuations of vortices in the strongly layered system.",0110232v1
+2001-10-22,Magnetoconductance of a two-dimensional metal in the presence of spin-orbit coupling,"We show that in the metallic phase of a two dimensional electron gas the
+spin-orbit coupling due to structure inversion asymmetry leads to a
+characteristic anisotropy in the magnetoconductance. Within the assumption that
+the metallic phase can be described by a Fermi liquid, we compute the
+conductivity in the presence of an in-plane magnetic field. Both the spin-orbit
+coupling and the Zeeman coupling with the magnetic field give rise to two spin
+subbands, in terms of which most of the transport properties can be discussed.
+  The strongest conductivity anisotropy occurs for Zeeman energies of the order
+of the Fermi energy corresponding to the depopulation of the upper spin
+subband. The energy scale associated with the spin-orbit coupling controls the
+strength of the effect. More in particular, we find that the detailed behavior
+and the sign of the anisotropy depends on the underlying scattering mechanism.
+Assuming small angle scattering to be the dominant scattering mechanism our
+results agree with recent measurement on Si-MOSFET's in the vicinity of the
+metal-insulator transition.",0110454v1
+2001-10-25,Observation of large anisotropy in c-axis oriented thin films of MgB$_{2}$ prepared by an in situ pulsed laser deposition process,"A large anisotropy in the upper critical field (H$_{C2}$) is observed for
+MgB$_{2}$ films grown in situ by a pulsed laser deposition process involving
+growth and annealing of Mg and B multilayers. Measurements of resistivity as a
+function of temperature and magnetic field yield the estimated zero temperature
+values of H$_{C2}$ in the range 100 to 130 T and about 10 T, for the field in
+ab plane and along c axis, respectively, depending on the criterion chosen for
+the transition temperature. The corresponding anisotropy parameter is thus in
+the range 9 to 13. The estimated coherence length in ab plane is about 50
+\r{A}, whereas that in the c direction is much smaller (\approx 5 \r{A}). No
+significant magnetoresistance is observed in the normal state.",0110541v1
+2001-12-07,The origin of second-order transverse magnetic anisotropy in Mn12-acetate,"The problem of the role of transverse fields in Mn12-acetate, a molecular
+nanomagnet, is still open. We present structural evidences that the disorder of
+the acetic acid of crystallization indices sizeable distortion of the Mn(III)
+sites, giving rise to six different isomers, four of them with symmetry lower
+than tetragonal. Using a ligand field approach the effect of the structure
+modifications on the second order transverse magnetic anisotropy, forbidden in
+tetragonal symmetry, has been evaluated. The order of magnitude of the
+quadratic transverse anisotropies well agree with the values derived by the
+analysis of the field sweep dependence of the hysteresis loops performed by
+Mertes et al.
+  (Phys. Rev. Lett 87, 227205 (2001)) and allows to better simulate the EPR
+spectra.",0112112v1
+2001-12-11,Temperature dependence and anisotropy of the bulk upper critical field H_c2 of MgB_2,"The bulk upper critical field H_{c2}(T) of superconducting MgB_2 and its
+anisotropy are established by analyzing experimental data on the temperature
+and magnetic field dependences of the ab-plane thermal conductivity of a
+single-crystalline sample in external magnetic fields oriented both parallel
+(H_{c2}^c) and perpendicular (H_{c2}^{ab}) to the c axis of the hexagonal
+lattice. From numerical fits we deduce the anisotropy ratio \gamma_0 =
+H_{c2}^{ab}(0) / H_{c2}^c(0)=4.2 at T=0 K. Both the values and the temperature
+dependences of H_{c2}^c and H_{c2}^{ab} are distinctly different from previous
+claims based on measurements of the electrical resistivity.",0112191v2
+2002-01-08,The effect of velocity anisotropy on the antiferromagnetic instability of a d-wave superconductor,"We consider the effective 2+1 dimensional electrodynamics (QED_3) of
+low-energy quasiparticles coupled to fluctuating vortex loops in the d-wave
+superconductor, with the velocity anisotropy: v_F not equal to v_Delta. This
+theory should be relevant to the quantum superconductor-insulator transition in
+underdoped cuprates. Working in the customary large-N approximation, we find
+that weak anisotropy is a marginally irrelevant perturbation to the Lorentz
+invariant QED_3, and that the critical number N_c of Dirac fields below which
+the theory suffers the antiferromagnetic (chiral) instability stays the same.",0201088v4
+2002-01-25,Anisotropic superconducting properties of MgB2 single crystals probed by in-plane electrical transport measurements,"We report on study of the electronic anisotropy of the newly discovered MgB2
+superconductor using the in-plane resistivity measurements in magnetic field
+applied perpendicular and parallel to Mg and B planes of MgB2 single crystals.
+The results show temperature dependent anisotropy of the upper critical field
+with anisotropy ratio increasing from 2.2 close to Tc up to about 3 below 30K.
+Our estimation of the in-plane and out-of-plane coherence length of about 68A
+and 23A and electronic mean-free path 240A and 60A respectively indicates MgB2
+single crystal as approaching clean limit type-II superconductor.",0201451v2
+2002-03-09,Density Induced Interchange of Anisotropy Axes at Half-Filled High Landau Levels,"We observe density induced 90$^{\circ}$ rotations of the anisotropy axes in
+transport measurements at half-filled high Landau levels in the two dimensional
+electron system, where stripe states are proposed ($\nu$=9/2, 11/2, etc). Using
+a field effect transistor, we find the transition density to be
+$2.9\times10^{11}$cm$^{-2}$ at $\nu$=9/2. Hysteresis is observed in the
+vicinity of the transition. We construct a phase boundary in the filling
+factor-magnetic field plane in the regime $4.4<\nu<4.6$. An in-plane magnetic
+field applied along either anisotropy axis always stabilizes the low density
+orientation of the stripes.",0203203v1
+2002-03-29,Femtosecond quasiparticle relaxation dynamics and probe polarization anisotropy in YBa2Cu4O8,"Femtosecond pump probe experiments are reported on quasiparticle relaxation
+and recombination in YBa2Cu4O8 as a function of temperature and polarization.
+The data show a 2-component relaxation similar to YBa2Cu3O7-\delta, one
+component being assocated with the superconducting transition, and the other
+with the pseudogap below T* The relaxation time tau_p associated with the
+pseudogap is found to be T-independent, while the relaxation time tau_g of the
+component obseved only below Tc exhibits a clear divergence near Tc. A strong
+polarisation anisotropy of the picosecond transient is observed below Tc which
+is attributed to the anisotropy of the probe transition matrix elements.",0203614v2
+2002-04-22,Magnetic Anisotropy in the Molecular Complex V15,"We apply degenerate perturbation theory to investigate the effects of
+magnetic anisotropy in the magnetic molecule V15. Magnetic anisotropy is
+introduced via Dzyaloshinskii-Moriya (DM) interaction in the full Hilbert space
+of the system. Our model provides an explanation for the rounding of
+transitions in the magnetization as a function of applied field at low
+temperature, from which an estimate for the DM interaction is found. We find
+that the calculated energy differences of the lowest energy states are
+consistent with the available data. Our model also offers a novel explanation
+for the hysteretic nature of the time-dependent magnetization data.",0204435v2
+2002-04-22,"Magnetic ordering, electronic structure and magnetic anisotropy energy in the high-spin Mn$_{10}$ single molecule magnet","We report the electronic structure and magnetic ordering of the single
+molecule magnet [Mn$_{10}$O$_{4}$(2,2'-biphenoxide)$_{4}$Br$_{12}$]$^{4-}$
+based on first-principles all-electron density-functional calculations. We find
+that two of the ten core Mn atoms are coupled antiferromagnetically to the
+remaining eight, resulting in a ferrimagnetic ground state with total spin
+S=13. The calculated magnetic anisotropy barrier is found to be 9 K in good
+agreement with experiment. The presence of the Br anions impact the electronic
+structure and therefore the magnetic properties of the 10 Mn atoms. However,
+the electric field due to the negative charges has no significant effect on the
+magnetic anisotropy.",0204479v1
+2002-04-30,"S=1 kagomé Ising model with triquadratic interactions, single-ion anisotropy and magnetic field: exact phase diagrams","We consider a S=1 kagom\'e Ising model with triquadratic interactions around
+each triangular face of the kagom\'e lattice, single-ion anisotropy and an
+applied magnetic field. A mapping establishes an equivalence between the
+magnetic canonical partition function of the model and the grand canonical
+partition function of a kagom\'e lattice-gas model with localized
+three-particle interactions. Since exact phase diagrams are known for
+condensation in the one-parameter lattice-gas model, the mapping directly
+provides the corresponding exact phase diagrams of the three-parameter S=1
+Ising model. As anisotropy competes with interactions, results include the
+appearance of confluent singularities effecting changes in the topology of the
+phase diagrams, phase boundary curves (magnetic field vs temperature) with
+purely positive or negative slopes as well as intermediate cases showing
+nonmonotonicity, and coexistence curves (magnetization vs temperature) with
+varying shapes and orientations, in some instances entrapping a homogeneous
+phase.",0204632v1
+2002-05-06,"Comment on ``Anisotropic s-wave superconductivity: comparison with experiments on MgB_2 [A. I. Posazhennikova, T. Dahm and K. Maki, cond-mat/0204272; submitted to Europhys. Lett.]","An analytical result for the renormalization of the jump of the heat capacity
+Delta C/C_N by the anisotropy of the order parameter is derived within the
+framework of the very recent model proposed by Posazhennikova, Dahm and Maki
+[cond-mat/0204272, submitted to Europhys. Lett.], for both oblate and prolate
+anisotropy. The graph of Delta C/C_N versus the ratio of the gaps on the
+equator and the pole of the Fermi surface, Delta_e/\Delta_p, allows a direct
+determination of the gap anisotropy parameter Delta_e/\Delta_p by fitting data
+from specific heat measurements Delta C/C_N. Using the experimental value Delta
+C/C_N=0.82 +/- 10% by Wang, Plackowski, and Junod [Physica C 355 (2001) 179] we
+find Delta_e/\Delta_p = 4.0.",0205104v3
+2002-05-10,Macroscopic Anisotropy and Symmetry Breaking in the Pyrochlore Antiferromagnet Gd$_{2}$Ti$_{2}$O$_{7}$},"In the Heisenberg antiferromagnet $Gd_2Ti_2O_7$, the exchange interactions
+are geometrically frustrated by the pyrochlore lattice structure. This ESR
+study reveals a strong temperature dependent anisotropy with respect to a [111]
+body diagonal below a temperature $T_A=80$ K, despite the spin only nature of
+the $Gd^{3+}$ ion. Anisotropy and symmetry breaking can nevertheless appear
+through the superexchange interaction. The presence of short range planar
+correlation restricted to specific Kagom\'{e} planes is sufficient to explain
+the two ESR modes studied in this work.",0205224v1
+2002-07-04,Specific heat of single crystal MgB_2: a two-band superconductor with two different anisotropies,"Heat-capacity measurements of a 39 microgramm MgB_2 single crystal in fields
+up to 14 T and below 3 K allow the determination of the low-temperature linear
+term of the specific heat, its field dependence and its anisotropy. Our results
+are compatible with two-band superconductivity, the band carrying the small gap
+being isotropic, that carrying the large gap having an anisotropy of ~ 5. Three
+different upper critical fields are thus needed to describe the superconducting
+state of MgB2.",0207141v3
+2002-07-08,Magnetic behavior of single crystalline Ho$_2$PdSi$_3$,"The magnetic behavior of single-crystal Ho$_2$PdSi$_3$, crystallizing in an
+AlB$_2$-derived hexagonal structure, is investigated by magnetic susceptibility
+($\chi$) and electrical resistivity ($\rho$) measurements along two directions.
+There is no dramatic anisotropy in the high temperature Curie-Weiss parameter
+or in the $\rho$ and isothermal magnetization data, though there is a
+noticeable anisotropy in the magnitude of $\rho$ between two perpendicular
+orientations. The degree of anisotropy is overall less prominent than in the Gd
+(which is an S-state ion!) and Tb analogues. A point of emphasis is that this
+compound undergoes long range magnetic ordering below 8 K as in the case of
+analogous Gd and Dy compounds. Considering this fact for these compounds with
+well-localised f-orbital, the spin glass freezing noted for isomorphous U
+compounds in the recent literature could be attributed to the role of the
+f-ligand hybridization, rather than just Pd-Si disorder.",0207199v1
+2002-07-18,Effects of superconducting gap anisotropy on the flux flow resistivity in Y(Ni_{1-x}Pt_x)_2B_2C,"The microwave complex surface impedance Z_s of Y(Ni_{1-x}Pt_x)_2B_2C was
+measured at 0.5 K under magnetic fields H up to 7T. In nominally pure
+YNi_2B_2C, which is a strongly anisotropic s-wave superconductor, the flux flow
+resistivity \rho_f calculated from Z_s was twice as large as that expected from
+the conventional normal-state vortex core model. In Pt-doped samples where the
+gap anisotropy is smeared out, the enhancement of \rho_f is reduced and \rho_f
+approaches to the conventional behavior. These results indicate that energy
+dissipation in the vortex core is strongly affected by the anisotropy of the
+superconducting gap.",0207454v1
+2002-07-29,Anisotropic Lattice Models of Electrolytes,"Systems of charged particles on anisotropic three-dimensional lattices are
+investigated theoretically using Debye-Huckel theory. It is found that the
+thermodynamics of these systems strongly depends on the degree of anisotropy.
+For weakly anisotropic simple cubic lattices, the results indicate the
+existence of order-disorder phase transitions and a tricritical point, while
+the possibility of low-density gas-liquid coexistence is suppressed. For
+strongly anisotropic lattices this picture changes dramatically: the
+low-density gas-liquid phase separation reappears and the phase diagram
+exhibits critical, tricritical and triple points. For body-centered lattices,
+the low-density gas-liquid phase coexistence is suppressed for all degrees of
+anisotropy. These results show that the effect of anisotropy in lattice models
+of electrolytes amounts to reduction of spatial dimensionality.",0207686v1
+2002-08-01,"Quantum Hall ferromagnets, cooperative transport anisotropy, and the random field Ising model","We discuss the behaviour of a quantum Hall system when two Landau levels with
+opposite spin and combined filling factor near unity are brought into energetic
+coincidence using an in-plane component of magnetic field. We focus on the
+interpretation of recent experiments under these conditions [Zeitler et al,
+Phys. Rev. Lett. 86, 866 (2001); Pan et al, Phys. Rev. B 64, 121305 (2001)], in
+which a large resistance anisotropy develops at low temperatures. Modelling the
+systems involved as Ising quantum Hall ferromagnets, we suggest that this
+transport anisotropy reflects domain formation induced by a random field
+arising from isotropic sample surface roughness.",0208024v1
+2002-11-12,Reciprocity theorem in high-temperature superconductors,"This article is devoted to the problem of the validity of the reciprocity
+theorem in high-temperature superconductors (HTSC). The violation of the
+reciprocity theorem in zero external magnetic fields has been studied.
+Experimental data obtained for two different superconducting materials:
+BiSrCaCuO and YBaCuO are presented. Results show that the basic form of the
+reciprocity theorem (without consideration of any additional anisotropy) is not
+valid near the critical temperature. We assume that the reciprocity theorem
+breaking is connected with the existence of an extraordinary transverse
+electric field originated from additional anisotropy and more general form of
+the reciprocity relations should be valid. However, the origin of this
+anisotropy is not clear yet. We suggest that the vortex-antivortex dynamics
+model taking into account vortex guiding can be responsible for the observed
+effect. Also the explanation based on weak P and T symmetry breaking in HTSC
+which is supported by the observation of the spontaneous magnetisation can not
+be excluded.",0211233v1
+2002-11-23,Binder Parameter of a Heisenberg Spin-Glass Model in Four Dimensions,"We studied the phase transition of the $\pm J$ Heisenberg model with and
+without a random anisotropy on four dimensional lattice $L\times L\times
+L\times (L+1)$ $(L\leq 9)$. We showed that the Binder parameters $g(L,T)$'s for
+different sizes do not cross even when the anisotropy is present. On the
+contrary, when a strong anisotropy exists, $g(L,T)$ exhibits a steep negative
+dip near the spin-glass phase transition temperature $T_{\rm SG}$ similarly to
+the $p-$state infinite-range Potts glass model with $p \geq 3$, in which the
+one-step replica-symmetry-breaking (RSB) occurs. We speculated that a one-step
+RSB-like state occurs below $T_{\rm SG}$, which breaks the usual crossing
+behavior of $g(L,T)$.",0211521v1
+2002-12-02,Anisotropic Optic Conductivities due to Spin and Orbital Orderings in LaVO3 and YVO3: First-Principles Studies,"The anisotropy of low energy (0$\sim$5eV) optical excitations in strongly
+correlated transition-metal oxides is closely related to the spin and orbital
+orderings. The recent successes of LDA+$U$ method in describing the magnetic
+and electronic structures enable us to calculate the optical conductivity from
+first-principles. The LaVO$_3$ and YVO$_3$, both of which have $3d^2$
+configuration and have various spin and orbital ordered phases at low
+temperature, show distinct anisotropy in the optical spectra. The effects of
+spin and orbital ordering on the anisotropy are studied in detail based on our
+first-principles calculations. The experimental spectra of both compounds at
+low temperature phases can be qualitatively explained with our calculations,
+while the studies for the intermediate temperature phase of YVO$_3$ suggest the
+substantial persistence of the low temperature phase at elevated temperature.",0212024v1
+2002-12-09,Fermi surface topology and the upper critical field in two-band superconductors - application to MgB2,"Recent measurements of the anisotropy of the upper critical field Bc2 on MgB2
+single crystals have shown a puzzling strong temperature dependence. Here, we
+present a calculation of the upper critical field based on a detailed modeling
+of bandstructure calculations that takes into account both the unusual Fermi
+surface topology and the two gap nature of the superconducting order parameter.
+Our results show that the strong temperature dependence of the Bc2 anisotropy
+can be understood as an interplay of the dominating gap on the sigma-band,
+which possesses a small c-axis component of the Fermi velocity, with the
+induced superconductivity on the pi-band possessing a large c-axis component of
+the Fermi velocity. We provide analytic formulas for the anisotropy ratio at
+T=0 and T=Tc and quantitatively predict the distortion of the vortex lattice
+based on our calculations.",0212188v3
+2002-12-10,Solution of mass/gap equations for strong velocity anisotropy in the QED3 theory of underdoped cuprates,"The low-lying excitations at the nodes of the d-wave gap in the normal state
+for underdoped cuprates, close to the superconducting phase transition, may be
+described by an effective QED3 theory. There are three characteristic
+velocities: v_F, v_Delta and c. For v_Delta=v_F=c, the model reduces to
+N-flavour QED3. Here, in the isotropic limit, for N<N_0c, a critical number of
+fermions, a dynamical mass is generated which corresponds to the formation of a
+spin density wave. We study the effects of strong velocity anisotropy (v_F \neq
+v_\Delta) on dynamical mass generation. Solutions are given for the dynamical
+mass at both N=2 and N=100, and so we show that the critical number of fermions
+N_c>100. However, we argue that N_c=N_0c, when we go beyond the approximations
+used to derive our mass gap equations. We expect, though, that our solution for
+N=2 is roughly correct, at low momentum, for large enough anisotropies.
+Implications and possible extensions to this work are also discussed.",0212204v2
+2003-01-21,Ferromagnetic coupling and magnetic anisotropy in molecular Ni(II) squares,"We investigated the magnetic properties of two isostructural Ni(II) metal
+complexes [Ni4Lb8] and [Ni4Lc8]. In each molecule the four Ni(II) centers form
+almost perfect regular squares. Magnetic coupling and anisotropy of single
+crystals were examined by magnetization measurements and in particular by
+high-field torque magnetometry at low temperatures. The data were analyzed in
+terms of an effective spin Hamiltonian appropriate for Ni(II) centers. For both
+compounds, we found a weak intramolecular ferromagnetic coupling of the four
+Ni(II) spins and sizable single-ion anisotropies of the easy-axis type. The
+coupling strengths are roughly identical for both compounds, whereas the
+zero-field-splitting parameters are significantly different. Possible reasons
+for this observation are discussed.",0301373v1
+2003-02-14,Anisotropy of heavy hole spin splitting and interference effects of optical polarization in semiconductor quantum wells subjected to an in-plane magnetic field,"Strong effects of optical polarization anisotropy observed previously in the
+quantum wells subjected to the in-plane magnetic field arrive at complete
+description within microscopic approach. Theory we develop involves two sources
+of optical polarization. First source is due to correlations between electron
+and heavy hole (HH) phases of $\psi $-functions arising due to electron Zeeman
+spin splitting and joint manifestation of low-symmetry and Zeeman interactions
+of HH in an in-plane magnetic field. In this case, four possible
+phase-controlled electron-HH transitions constitute the polarization effect,
+which can reach its maximal amount ($\pm $1) at low temperatures when only one
+transition survives. Other polarization source stems from the admixture of
+excited light-holes (LH) states to HH by low-symmetry interactions. The
+contribution of this mechanism to total polarization is relatively small but it
+can be independent of temperature and magnetic field. Analysis of different
+mechanisms of HH splitting exhibits their strong polarization anisotropy. Joint
+action of these mechanisms can result in new peculiarities, which should be
+taken into account for explanation of different experimental situations.",0302301v2
+2003-03-06,Strong 3D correlations in vortex system of Bi2212:Pb,"The experimental study of magnetic flux penetration under crossed magnetic
+fields in Bi2212:Pb single crystal performed by magnetooptic technique (MO)
+reveals remarkable field penetration pattern alteration (flux configuration
+change) and superconducting current anisotropy enhancement by the in-plane
+field. The anisotropy increases with the temperature rise up to $T_m = 54 \pm 2
+K$. At $T = T_m$ an abrupt change in the flux behavior is found; the
+correlation between the in-plane magnetic field and the out-of-plane magnetic
+flux penetration disappears. No correlation is observed for $T > T_m$. The
+transition temperature $T_m$ does not depend on the magnetic field strength.
+The observed flux penetration anisotropy is considered as an evidence of a
+strong 3D - correlation between pancake vortices in different CuO planes at $T
+< T_m$. This enables understanding of a remarkable pinning observed in
+Bi2212:Pb at low temperatures.",0303103v1
+2003-03-12,Upper critical field in dirty two-band superconductors: breakdown of the anisotropic Ginzburg-Landau theory,"We investigate the upper critical field in a dirty two-band superconductor
+within quasiclassical Usadel equations. The regime of very high anisotropy in
+the quasi-2D band, relevant for MgB$_{2}$, is considered. We show that strong
+disparities in pairing interactions and diffusion constant anisotropies for two
+bands influence the in-plane $H_{c2}$ in a different way at high and low
+temperatures. This causes temperature-dependent $H_{c2}$ anisotropy, in
+accordance with recent experimental data in MgB$_{2}$. The three-dimensional
+band most strongly influences the in-plane $H_{c2}$ near $T_{c}$, in the
+Ginzburg-Landau (GL) region. However, due to a very large difference between
+the c-axis coherence lengths in the two bands, the GL theory is applicable only
+in an extremely narrow temperature range near $T_c$. The angular dependence of
+$H_{c2}$ deviates from a simple effective-mass law even near $T_c$.",0303237v1
+2003-03-26,Frozen Quasi Long Range Order in Random Anisotropy Heisenberg Magnet,"Extensive Monte Carlo simulations are used to investigate the low-temperature
+properties of the random anisotropy Heisenberg model, which describes the
+magnetic behavior of amorphous rare-earth-transition metal alloy. We show that
+the low-temperature phase in weak-anisotropy region is characterized by a {\it
+frozen-in} power-law spin-spin correlation. Numerical observation of the
+power-law exponent $\eta$ indicates nonuniversal behavior.",0303552v4
+2003-04-01,Study of the influence of surface anisotropy and lattice structure on the behaviour of a small magnetic cluster,"We have studied by Monte Carlo simulations the thermal behaviour of a small
+(N=13 particles) cluster described by a Heisenberg model, including
+nearest-neighbour ferromagnetic interactions and radial surface anisotropy, in
+an applied magnetic field. We have studied three different lattice structures:
+hexagonal close packed, face centered cubic and icosahedral. We show that the
+zero-field thermal behaviour depends not only on the value of the anisotropy
+constant but also on the lattice structure. The behaviour in an applied field,
+additionally depends, on the different orientations of the field with respect
+to the crystal axes. According to these relative orientations, hysteresis
+cycles show different step-like characteristics.",0304015v2
+2003-05-26,Macroturbulent Instability of the Flux Line Lattice in Anisotropic Superconductors,"A theory of the macroturbulent instability in the system containing vortices
+of opposite directions (vortices and antivortices) in hard superconductors is
+proposed. The origin of the instability is connected with the anisotropy of the
+current capability in the sample plane. The anisotropy results in the
+appearance of tangential discontinuity of the hydrodynamic velocity of vortex
+and antivortex motion near the front of magnetization reversal. As is known
+from the classical hydrodynamics of viscous fluids, this leads to the
+turbulization of flow. The examination is performed on the basis of the
+anisotropic power-law current-voltage characteristics. The dispersion equation
+for the dependence of the instability increment on the wave number of
+perturbation is obtained, solved, and analyzed analytically and numerically. It
+is shown that the instability can be observed even at relatively weak
+anisotropy.",0305589v1
+2003-05-29,Influence of spin structures and nesting on Fermi surface and a pseudogap anisotropy in t-t'-U Hubbard model,"Influence of two type of spin structures on the form of the Fermi surface
+(FS) and a photoemission intensity map is studied for t-t'-U Hubbard model.
+Mean field calculations are done for the stripe phase and for the spiral spin
+structure. It is shown, that unlike a case of electron doping, the hole-doped
+models are unstable with respect to formation of such structures. The pseudogap
+anisotropies are different for h- and e- doping. In accordance with ARPES data
+for La2SrxCuO4 the stripe phase is characterized by quasi-one-dimensional
+segments of FS at k=(\pi,0) and by suppression of spectral weight in diagonal
+direction. It is shown that spiral structures display the polarisation
+anisotropy: different segments of FS correspond to electros with different spin
+polarisations.",0305685v1
+2003-06-19,Spatial anisotropy of the exciton level in CaF$_2$ at 11.1 eV and its relation to the weak optical anisotropy at 157 nm,"The energy level of the exciton around the $\Gamma$ point in CaF$_2$ at about
+11.1 eV was investigated by reflection measurements on oriented surfaces using
+dispersed synchrotron radiation. A small but clear energy shift of the exciton
+resonance structure was observed which depends on the crystal orientation with
+respect to the incoming beam. By interpreting the results in terms of the
+complex dielectric function it becomes possible to determin the respective
+exciton levels and lifetimes. For crystal samples oriented in the (111)
+direction, the exciton has an excitation energy 0.02 eV above the energy of
+samples oriented in the (100) direction. The results obtained suggest that the
+exciton-energy shift is related to the spatial anisotropy recently measured in
+CaF$_2$ at 157 nm.",0306510v1
+2003-07-18,Thermodynamics of Electrolytes on Anisotropic Lattices,"The phase behavior of ionic fluids on simple cubic and tetragonal
+(anisotropic) lattices has been studied by grand canonical Monte Carlo
+simulations. Systems with both the true lattice Coulombic potential and
+continuous-space $1/r$ electrostatic interactions have been investigated. At
+all degrees of anisotropy, only coexistence between a disordered low-density
+phase and an ordered high-density phase with the structure similar to ionic
+crystal was found, in contrast to recent theoretical predictions. Tricritical
+parameters were determined to be monotonously increasing functions of
+anisotropy parameters which is consistent with theoretical calculations based
+on the Debye-H\""uckel approach. At large anisotropies a two-dimensional-like
+behavior is observed, from which we estimated the dimensionless tricritical
+temperature and density for the two-dimensional square lattice electrolyte to
+be $T^*_{tri}=0.14$ and $\rho^*_{tri} = 0.70$.",0307472v1
+2003-08-26,Anisotropy in the Antiferromagnetic Spin Fluctuations of Sr2RuO4,"It has been proposed that Sr_2RuO_4 exhibits spin triplet superconductivity
+mediated by ferromagnetic fluctuations. So far neutron scattering experiments
+have failed to detect any clear evidence of ferromagnetic spin fluctuations
+but, instead, this type of experiments has been successful in confirming the
+existence of incommensurate spin fluctuations near q=(1/3 1/3 0). For this
+reason there have been many efforts to associate the contributions of such
+incommensurate fluctuations to the mechanism of its superconductivity. Our
+unpolarized inelastic neutron scattering measurements revealed that these
+incommensurate spin fluctuations possess c-axis anisotropy with an anisotropic
+factor \chi''_{c}/\chi''_{a,b} of \sim 2.8. This result is consistent with some
+theoretical ideas that the incommensurate spin fluctuations with a c-axis
+anisotropy can be a origin of p-wave superconductivity of this material.",0308521v2
+2003-09-12,Anisotropy of exchange stiffness and its effect on the properties of magnets,"Using the spin-spiral formulation of the tight-binding linear muffin-tin
+orbital method, the principal components of the exchange stiffness tensor are
+calculated for typical hard magnets including tetragonal CoPt-type and
+hexagonal YCo5 alloys. The exchange stiffness is strongly anisotropic in all
+studied alloys. This anisotropy makes the domain wall surface tension
+anisotropic. Competition between this anisotropic surface tension and
+magnetostatic energy controls the formation and dynamics of nanoscale domain
+structures in hard magnets. Anisotropic domain wall bending is described in
+detail from the general point of view and with application to cellular Sm-Co
+magnets. It is shown that the repulsive cell-boundary pinning mechanism in
+these magnets is feasible only due to the anisotropic exchange stiffness if
+suitably oriented initial pinning centers are available. In polytwinned
+CoPt-type magnets the exchange stiffness anisotropy controls the orientation of
+macrodomain wall segments. These segments may reorient both statically during
+microstructural coarsening and dynamically during the macrodomain wall
+splitting in external field. Reorientation of segments may facilitate their
+pinning at antiphase boundaries.",0309321v1
+2003-11-19,New Anisotropic Behavior of Quantum Hall Resistance in (110) GaAs Heterostructures at mK Temperatures and Fractional Filling Factors,"Transport experiments in high mobility (110) GaAs heterostructures have been
+performed at very low temperatures 8 mK. At higher Landau-Levels we observe a
+transport anisotropy that bears some similarity with what is already seen at
+half-odd-integer filling on (001) oriented substrates. In addition we report
+the first observation of transport anisotropies within the lowest Landau-Level.
+This remarkable new anisotropy is independent of the current direction and
+depends on the polarity of the magnetic field.",0311454v2
+2003-12-10,Second-order transverse magnetic anisotropy induced by disorders in the single-molecule magnet Mn12,"For the single-molecule magnet Mn12, Cornia et al. recently proposed that
+solvent molecules may cause the quantum tunneling that requires a lower
+symmetry than S4. However, magnetic quantum tunneling and electron paramagnetic
+resonance experiments suggested that the proposed theory may not correspond to
+the measurements. In this regard, we consider positional disorder induced by
+the solvent molecules and orientational disorder by the methyl groups of a Mn12
+molecule. We calculate, within density-functional theory, the second-order
+transverse magnetic anisotropy parameter E and an easy-axis tilting angle
+induced by the positional disorder and the E value by the orientational
+disorder. We also calculate the local magnetic anisotropy and the local easy
+axis for each inequivalent Mn site in different environments to investigate
+their effects on the global E value. We find that the hydrogen bonding between
+a Mn12 molecule and the solvent molecule is crucial to obtain a substantial E
+value and that the E value increases upon geometry relaxations. Our
+calculations on relaxed geometries show that the largest calculated E value is
+0.016 K and that the largest tilting angle is 0.5 degrees. Our largest E value
+is comparable to experimental results but larger than Cornia et al.'s.",0312261v1
+2003-12-19,Magnetisation switching in a ferromagnetic Heisenberg nanoparticle with uniaxial anisotropy: A Monte Carlo investigation,"We investigate the thermal activated magnetisation reversal in a single
+ferromagnetic nanoparticle with uniaxial anisotropy using Monte Carlo
+simulations. The aim of this work is to reproduce the reversal magnetisation by
+uniform rotation at very low temperature in the high energy barrier hypothesis,
+that is to realize the N\'eel-Brown model. For this purpose we have considered
+a simple cubic nanoparticle where each site is occupied by a classical
+Heisenberg spin. The Hamiltonian is the sum of an exchange interaction term, a
+single-ion anisotropy term and a Zeeman interaction term. Our numerical data of
+the thermal variation of the switching field are compared to an approximated
+expression and previous experimental results on Co nanoparticles.",0312536v1
+2004-04-03,Macroscopic Quantum Tunneling in Small Antiferromagnetic Particles: Effects of a Strong Magnetic Field,"We consider an effect of a strong magnetic field on the ground state and
+macroscopic coherent tunneling in small antiferromagnetic particles with
+uniaxial and biaxial single-ion anisotropy. We find several tunneling regimes
+that depend on the direction of the magnetic field with respect to the
+anisotropy axes. For the case of a purely uniaxial symmetry and the field
+directed along the easy axis, an exact instanton solution with two different
+scales in imaginary time is constructed. For a rhombic anisotropy the effect of
+the field strongly depends on its orientation: with the field increasing, the
+tunneling rate increases or decreases for the field parallel to the easy or
+medium axis, respectively. The analytical results are complemented by numerical
+simulations.",0404069v2
+2004-04-14,"Exchange interactions and magnetic anisotropy in the ""Ni_4"" magnetic molecule","Magnetic properties of a tetrahedral ""Ni_4"" molecule are discussed in terms
+of the Heisenberg model, with magnetic anisotropy terms included, and on the
+basis of first-principle calculations within the density functional theory. It
+is shown that the isotropic Heisenberg model does not provide an adequate
+description of magnetization at low temperatures; an inclusion of single-site
+anisotropy terms does not help to improve the situation either. We suppose that
+the magnetostriction of the molecule and hence the dependence of interatomic
+coupling parameters on the magnetization might be important for an adequate
+description of magnetic properties. The first-principle calculations confirm
+the system's general preference for antiferromagnetic coupling, as well as the
+failure of the isotropic Heisenberg model. A conjugated-gradient search for the
+relaxed structure of the ""Ni_4"" molecule in ferromagnetic and antiferromagnetic
+configurations did not show any clear tendency to diversification of
+interatomic distances. These calculations however have not yet included the
+spin-orbit coupling, which can be essential for analyzing the effects of
+magnetostriction.",0404343v1
+2004-06-11,Role of surface anisotropy for magnetic impurities in electron dephasing and energy relaxation and their size effect,"Recently the electron dephasing and energy relaxation due to different
+magnetic impurities have been extensively investigated experimentally in thin
+wires and in this Letter these quantities are theoretically studied. It was
+shown earlier that a magnetic impurity in a metallic host with strong
+spin-orbit interaction experiences a surface anisotropy of the form $H=K_d
+({\bf n}{\bf S})^2$ which causes size effects for impurities with integer spin.
+Here we show that the dephasing and the energy relaxation are influenced by the
+surface anisotropy in very different ways for integer spin having a singlet
+ground state. That must result also in strong size effects and may resolve the
+puzzle between the concentrations estimated from the two kind of experiments.",0406277v3
+2004-07-20,The interplay between screening properties and colloid anisotropy: towards a reliable pair potential for disc-like charged particles,"The electrostatic potential of a highly charged disc (clay platelet) in an
+electrolyte is investigated in detail. The corresponding non-linear
+Poisson-Boltzmann (PB) equation is solved numerically, and we show that the
+far-field behaviour (relevant for colloidal interactions in dilute suspensions)
+is exactly that obtained within linearized PB theory, with the surface boundary
+condition of a uniform potential. The latter linear problem is solved by a new
+semi-analytical procedure and both the potential amplitude (quantified by an
+effective charge) and potential anisotropy coincide closely within PB and
+linearized PB, provided the disc bare charge is high enough. This anisotropy
+remains at all scales; it is encoded in a function that may vary over several
+orders of magnitude depending on the azimuthal angle under which the disc is
+seen. The results allow to construct a pair potential for discs interaction,
+that is strongly orientation dependent.",0407521v1
+2004-07-29,Temperature dependent magnetic anisotropy in metallic magnets from an ab-initio electronic structure theory: L1_0-ordered FePt,"On the basis of a first-principles, relativistic electronic structure theory
+of finite temperature metallic magnetism, we investigate the variation of
+magnetic anisotropy, K, with magnetisation, M, in metallic ferromagnets. We
+apply the theory to the high magnetic anisotropy material, L1_0-ordered FePt,
+and find its uniaxial K consistent with a magnetic easy axis perpendicular to
+the Fe/Pt layering for all M and to be proportional to M^2 for a broad range of
+values of M. For small M, near the Curie temperature, the calculations pick out
+the easy axis for the onset of magnetic order. Our results are in good
+agreement with recent experimental measurements on this important magnetic
+material.",0407774v1
+2004-08-02,Ab initio study of reflectance anisotropy spectra of a sub-monolayer oxidized Si(100) surface,"The effects of oxygen adsorption on the reflectance anisotropy spectrum (RAS)
+of reconstructed Si(100):O surfaces at sub-monolayer coverage (first stages of
+oxidation) have been studied by an ab initio DFT-LDA scheme within a
+plane-wave, norm-conserving pseudopotential approach. Dangling bonds and the
+main features of the characteristic RAS of the clean Si(100) surface are mostly
+preserved after oxidation of 50% of the surface dimers, with some visible
+changes: a small red shift of the first peak, and the appearance of a distinct
+spectral structure at about 1.5 eV. The electronic transitions involved in the
+latter have been analyzed through state-by-state and layer-by-layer
+decompositions of the RAS. We suggest that new interplay between present
+theoretical results and reflectance anisotropy spectroscopy experiments could
+lead to further clarification of structural and kinetic details of the Si(100)
+oxidation process in the sub-monolayer range.",0408028v2
+2004-08-30,Anisotropy-driven transition from collisionless to collisional regime in the dipolar modes of a trapped gaseous mixture,"We evaluate the dipolar oscillations of a harmonically trapped fermion gas
+containing thermal bosonic impurities as a function of the anisotropy of the
+trap, from the numerical solution of the Vlasov-Landau equations for the
+one-body phase-space distribution functions. Starting from a situation in which
+the two components of the gaseous mixture perform almost independent
+oscillations inside a spherical trap, we demonstrate that different collision
+behaviors arise for oscillations in different directions as the trap is
+deformed into an elongated cigar-like shape. An increase in the anisotropy of
+the confinement thus suffices to drive a transition of dipolar modes from a
+collisionless to a collisional regime.",0408654v2
+2004-09-02,Spin-orbit coupling and anisotropy of spin splitting in quantum dots,"In lateral quantum dots, the combined effect of both Dresselhaus and
+Bychkov-Rashba spin orbit coupling is equivalent to an effective magnetic field
+B_so which has the opposite sign for s_z=1/2 spin electrons. When the external
+magnetic field is perpendicular to the planar structure, the field B_so
+generates an additional splitting for electron states as compared to the spin
+splitting in the in-plane field orientation. The anisotropy of spin splitting
+has been measured and then analyzed in terms of spin-orbit coupling in several
+AlGaAs/GaAs quantum dots by means of resonanat tunneling spectroscopy. From the
+measured values and sign of the anisotropy we are able to determine the
+dominating spin-orbit coupling mechanism.",0409054v1
+2004-09-08,Incommensurate Transverse Anisotropy Induced by Disorder and Spin-Orbit-Vibron Coupling in Mn12-acetate,"It has been shown within density-functional theory that in Mn$_{12}$-acetate
+there are effects due to disorder by solvent molecules and a coupling between
+vibrational and electronic degrees of freedom. We calculate the in-plane
+principal axes of the second-order anisotropy caused by the second effect and
+compare them with those of the fourth-order anisotropy due to the first effect.
+We find that the two types of the principal axes are not commensurate with each
+other, which results in a complete quenching of the tunnel-splitting
+oscillation as a function of an applied transverse field.",0409206v1
+2004-10-21,"In-plane uniaxial anisotropy rotations in (Ga,Mn)As thin films","We show, by SQUID magnetometry, that in (Ga,Mn)As films the in-plane uniaxial
+magnetic easy axis is consistently associated with particular crystallographic
+directions and that it can be rotated from the [-110] direction to the [110]
+direction by low temperature annealing. We show that this behavior is
+hole-density-dependent and does not originate from surface anisotropy. The
+presence of uniaxial anisotropy as well its dependence on the
+hole-concentration and temperature can be explained in terms of the p-d Zener
+model of the ferromagnetism assuming a small trigonal distortion.",0410544v1
+2004-12-20,Quasiclassical Theory for Thermodynamic Properties of the Two-Band Superconductor MgB$_2$ under Magnetic Fields,"Consistent account is provided of strongly anisotropic properties in
+thermodynamics of MgB$_2$ under magnetic field $H$ using approximate analytic
+solution in the quasiclassical formalism. With the strength of the pairing
+interactions and the Fermi velocities of two bands as fitting parameters, it is
+possible to reproduce in wide regions of the phase diagram the $H$- and
+temperature dependences of relevant quantities such as the zero-energy density
+of states (ZEDOS), two energy gaps, the specific heat and the $H_{c2}$
+anisotropy. It is demonstrated that the velocity ratio of two bands affects
+considerably the low-field behavior of the ZEDOS and energy gaps. The ratio
+also affects the high-temperature behavior of the $H_{c2}$ anisotropy. The
+anisotropy of the coherence length in the $\sigma$ band depends weakly on $H$
+and $T$, whereas the coherence length in the $\pi$ band remains isotropic even
+in the presence of the inter-band coupling.",0412522v2
+2005-01-04,Anisotropy of spin splitting and spin relaxation in lateral quantum dots,"Inelastic spin relaxation and spin splitting $\epsilon_{\mathrm{s}}$ in
+lateral quantum dots are studied in the regime of strong in-plane magnetic
+field. Due to both g-factor energy dependence and spin-orbit coupling
+$\epsilon_{\mathrm{s}}$ demonstrates a substantial non-linear magnetic field
+dependence similar to that observed by R.Hanson \textit{et al} [Phys. Rev.
+Lett. \textbf{91}, 196802 (2003)]. It also varies with the in-plane orientation
+of magnetic field due to crystalline anisotropy of spin-orbit coupling. Spin
+relaxation rate is also anisotropic, the anisotropy increasing with the field.
+When the magnetic length is less than the 'thickness' of GaAs dot, the
+relaxation can be order of magnitude faster for $\mathbf{B}% \Vert\lbrack100]$
+than for $\mathbf{B\Vert}[110]$.",0501046v1
+2005-04-27,The effect of stripe domain structure on dynamic permeability of thin ferromagnetic films with out-of-plane uniaxial anisotropy,"The permeability is calculated for a thin ferromagnetic film with the stripe
+domain structure and out-of-plane uniaxial magnetic anisotropy. Analytical
+expressions for the frequency dependence of components of permeability tensor
+are derived with the use of the Smit-Beljers method, with the thickness of
+domain walls and the domain wall motion being neglected. The effect of the
+domain width and the angle between the anisotropy axis and the film plane on
+the frequency dependence of the permeability is analyzed. General equations
+relating the static permeability components and the ferromagnetic resonance
+frequencies are found. The results of the approach are applied to the
+derivation of the constraint for the microwave permeability of thin
+ferromagnetic films. The analysis of the constraint as a function of the axis
+deviation angle, the domain aspect ratio and the damping parameter allows the
+conditions to be found for maximal microwave permeability. The results obtained
+may be useful in connection with the problem of developing high-permeable
+microwave magnetic materials.",0504710v1
+2005-05-06,Cascade of two-dimensional Fulde-Ferrell-Larkin-Ovchinnikov phases with anisotropy,"For an isotropic two-dimensional system, when the temperature is lowered
+toward T=0, it has been found recently that, for the transition from the normal
+to the superfluid state in the paramagnetic limit, the order parameter
+describing the Fulde-Ferrell-Larkin-Ovchinnikov phase has an increasingly
+complex structure with contributions from an increasing number of wavevectors.
+This cascade of phase transitions is directly linked to the fact that, due to
+the rotational invariance, all the wavevectors directions which can enter the
+order parameter are degenerate. We study how this cascade of phase transitions
+is modified when one takes into account the anisotropy arising in a real solid
+state compound. For a simple model of anisotropy with elliptical dispersion
+relation, we find surprisingly that the cascade of phase transitions is not
+modified and the degeneracy with respect to the wavevector direction is still
+present. When we take into account a deviation with respect to this elliptical
+model, which is treated to first order in perturbation, we find that the
+degeneracy is lifted and that, basically, a single wavevector is favored right
+at the transition. However when one enters the superfluid phase, additional
+wavevectors come in the order parameter and the cascade of transitions is still
+present, though in a modified form.",0505155v1
+2005-05-07,Polyconvex Model for Materials with Cubic Anisotropy,"Polyconvexity is one of the known conditions which guarantee existence of
+solutions of boundary value problems in finite elasticity. In this work we
+propose a framework for development of polyconvex strain energy functions for
+hyperelastic materials with cubic anisotropy. The anisotropy is captured by a
+single fourth order structural tensor for which the minimal polynomial basis is
+identified and used for the formulation of the strain energy functions. After
+proving the polyconvexity of some polynomial terms, we proceed to propose a
+model based on a simple strain energy function. We investigate the behavior of
+the model analytically in one dimension and numerically in two and three
+dimensions. These investigations allow us conclude that the model possesses the
+physically relevant directional properties, in particular, strains in different
+directions are different and the lack of any loading symmetries leads to
+development of ``shear'' stresses and displacements.",0505178v1
+2005-05-08,Quantum analogue of the spin-flop transition for a spin pair,"Quantum (step-like) magnetization curves are studies for a spin pair with
+antiferromagnetic coupling in the presence of a magnetic field parallel to the
+easy axis of the magnetic anisotropy. The consideration is done both
+analytically and numerically for a wide range of the anisotropy constants and
+spins up to $S \gtrsim 100$. Depending on the origin of the anisotropy
+(exchange or single-ion), the magnetization curve can demonstrate the jumps
+more than unity and the concentration of the unit jumps in a narrow range of
+the field. We also point the region of the problem parameters, where the
+behavior is quasiclassical for $S = 5$, and where system is substantially
+quantum in the limit $S \to \infty$.",0505188v1
+2005-05-10,Interplay between magnetic anisotropy and interlayer coupling in nanosecond magnetization reversal of spin-valve trilayers,"The influence of magnetic anisotropy on nanosecond magnetization reversal in
+coupled FeNi/Cu/Co trilayers was studied using a photoelectron emission
+microscope combined with x-ray magnetic circular dicroism. In quasi-isotropic
+samples the reversal of the soft FeNi layer is determined by domain wall
+pinning that leads to the formation of small and irregular domains. In samples
+with uniaxial magnetic anisotropy, the domains are larger and the influence of
+local interlayer coupling dominates the domain structure and the reversal of
+the FeNi layer.",0505240v1
+2005-05-26,Exact results of a mixed spin-1/2 and spin-S Ising model on a bathroom tile (4-8) lattice: effect of uniaxial single-ion anisotropy,"Effect of uniaxial single-ion anisotropy upon magnetic properties of a mixed
+spin-1/2 and spin-S (S>=1) Ising model on a bathroom tile (4-8) lattice is
+examined within the framework of an exact star-triangle mapping transformation.
+The particular attention is focused on the phase diagrams established for
+several values of the quantum spin number S. It is shown that the mixed-spin
+bathroom tile lattice exhibits very similar phase boundaries as the mixed-spin
+honeycomb lattice whose critical points are merely slightly enhanced with
+respect to the former ones. The influence of uniaxial single-ion anisotropy
+upon the total magnetization vs. temperature dependence is particularly
+investigated as well.",0505638v2
+2005-06-23,Theory of Anisotropic Hopping Transport due to Spiral Correlations in the Spin-Glass Phase of Underdoped Cuprates,"We study the in-plane resistivity anisotropy in the spin-glass phase of the
+high-$T_{c}$ cuprates, on the basis of holes moving in a spiral spin
+background. This picture follows from analysis of the extended $t-J$ model with
+Coulomb impurities. In the variable-range hopping regime the resistivity
+anisotropy is found to have a maximum value of around 90%, and it decreases
+with temperature, in excellent agreement with experiments in
+La$_{2-x}$Sr$_x$CuO$_4$. In our approach the transport anisotropy is due to the
+non-collinearity of the spiral spin state, rather than an intrinsic tendency of
+the charges to self-organize.",0506604v3
+2005-07-05,Effect of second-rank random anisotropy on critical phenomena of random field O(N) spin model in the large N limit,"We study the critical behavior of a random field O($N$) spin model with a
+second-rank random anisotropy term in spatial dimensions $4<d<6$, by means of
+the replica method and the 1/N expansion. We obtain a replica-symmetric
+solution of the saddle-point equation, and we find the phase transition obeying
+dimensional reduction. We study the stability of the replica-symmetric saddle
+point against the fluctuation induced by the second-rank random anisotropy. We
+show that the eigenvalue of the Hessian at the replica-symmetric saddle point
+is strictly positive. Therefore, this saddle point is stable and the
+dimensional reduction holds in the 1/N expansion. To check the consistency with
+the functional renormalization group method, we obtain all fixed points of the
+renormalization group in the large $N$ limit and discuss their stability. We
+find that the analytic fixed point yielding the dimensional reduction is
+practically singly unstable in a coupling constant space of the given model
+with large $N$. Thus, we conclude that the dimensional reduction holds for
+sufficiently large $N$.",0507096v2
+2005-07-11,Critical slowing down in random anisotropy magnets,"We study the purely relaxational critical dynamics with non-conserved order
+parameter (model A critical dynamics) for three-dimensional magnets with
+disorder in a form of the random anisotropy axis. For the random axis
+anisotropic distribution, the static asymptotic critical behaviour coincides
+with that of random site Ising systems. Therefore the asymptotic critical
+dynamics is governed by the dynamical exponent of the random Ising model.
+However, the disorder influences considerably the dynamical behaviour in the
+non-asymptotic regime. We perform a field-theoretical renormalization group
+analysis within the minimal subtraction scheme in two-loop approximation to
+investigate asymptotic and effective critical dynamics of random anisotropy
+systems. The results demonstrate the non-monotonic behaviour of the dynamical
+effective critical exponent $z_{\rm eff}$.",0507241v1
+2005-07-20,All-optical probe of precessional magnetization dynamics in exchange biased NiFe/FeMn bilayers,"An internal anisotropy pulse field is launched by an 8.3 ps short laser
+excitation, which triggers precessional magnetization dynamics of a
+polycrystalline NiFe/FeMn exchange bias system on the picosecond timescale. Due
+to the excitation the unidirectional anisotropy and, thus, the exchange
+coupling across the interface between the ferromagnetic and the
+antiferromagnetic layer is reduced, leading to a fast reduction of the exchange
+bias field and to a dramatic increase of the zero-field susceptibility. The
+fast optical unpinning is followed by a slower recovery of the interfacial
+exchange coupling dominated by spin-lattice and heat flow relaxation with a
+time constant of the order of 160 ps. The measured picosecond time evolution of
+the exchange decoupling and restoration is interpreted as an anisotropy pulse
+field giving rise to fast precessional magnetization dynamics of the
+ferromagnetic layer. The strength of the internal pulse field and even the
+initial magnetization deflection direction from the equilibrium orientation can
+be controlled by the absorbed photons. The dependence of the effective Gilbert
+damping on both small and large angle precessional motion was studied, yielding
+that both cases can be modeled with reasonable accuracy within the
+Landau-Lifshitz and Gilbert framework.",0507475v1
+2005-09-01,Magnetic resonance study of the spin-reorientation transitions in the quasi-one-dimensional antiferromagnet BaCu2Si2O7,"A quasi-one dimensional antiferromagnet with a strong reduction of the
+ordered spin component, BaCu2Si2O7, is studied by the magnetic resonance
+technique in a wide field and frequency range. Besides of conventional
+spin-flop transition at the magnetic field parallel to the easy axis of spin
+ordering, magnetic resonance spectra indicate additional spin-reorientation
+transitions in all three principal orientations of magnetic field. At these
+additional transitions the spins rotate in the plane perpendicular to the
+magnetic field keeping the mutual arrangement of ordered spin components. The
+observed magnetic resonance spectra and spin-reorientation phase transitions
+are quantitatively described by a model including the anisotropy of transverse
+susceptibility with respect to the order parameter orientation. The anisotropy
+of the transverse susceptibility and the strong reduction of the anisotropy
+energy due to the quantum spin fluctuations are proposed to be the reason of
+the spin reorientations which are observed.",0509015v1
+2005-09-27,Charge-stripe phases versus a weak anisotropy of nearest-neighbor hopping,"Recently, we demonstrated rigorously the stability of charge-stripe phases in
+quantum-particle systems that are described by extended Falicov-Kimball
+Hamiltonians, with the quantum hopping particles being either spinless fermions
+or hardcore bosons. In this paper, by means of the same methods, we show that
+any anisotropy of nearest-neighbor hopping eliminates the $\pi/2$-rotation
+degeneracy of the so called dimeric and axial-stripe phases and orients them in
+the direction of a weaker hopping. Moreover, due to the same anisotropy the
+obtained phase diagrams of fermions show a tendency to become similar to those
+of hardcore bosons.",0509698v2
+2005-10-13,Spin gaps and magnetic structure of NaxCoO2,"We present two experiments that provide information on spin anisotropy and
+the magnetic structure of NaxCoO2. First, we report low-energy neutron
+inelastic scattering measurements of the zone-center magnetic excitations in
+the magnetically ordered phase of Na0.75CoO2. The energy spectra suggest the
+existence of two gaps, and are very well fitted by a spin-wave model with both
+in-plane and out-of-plane anisotropy terms. The gap energies decrease with
+increasing temperature and both gaps are found to have closed when the
+temperature exceeds the magnetic ordering temperature T_m~22 K. Secondly, we
+present neutron diffraction studies of Na0.85CoO2 with a magnetic field applied
+approximately parallel to the c axis. For fields in excess of ~8T a magnetic
+Bragg peak was observed at the (0,0,3) position in reciprocal space. We
+interpret this as a spin-flop transition of the A-type antiferromagnetic
+structure, and we show that the spin-flop field is consistent with the size of
+the anisotropy gap.",0510360v1
+2005-11-16,Monte Carlo simulations of ${\rm Ni Fe_2O_4}$ Nanoparticles,"We use Monte Carlo simulations to study ${\rm Ni Fe_2O_4}$ nanoparticles.
+Finite size and surface effects differentiate them from their bulk
+counterparts. A continuous version of the Wang-Landau algorithm is used to
+calculate the joint density of states $g(M_z, E)$ efficiently. From $g(M_z,
+E)$, we obtain the Bragg-Williams free energy of the particle, and other
+physical quantities. The hysteresis is observed when the nanoparticles have
+both surface disorder and surface anisotropy. We found that the finite
+coercivity is the result of interplay between surface disorder and surface
+anisotropy. If the surface disorder is absent or the surface anisotropy is
+relatively weak, the nanoparticles often exhibit superparamagnetism.",0511410v1
+2005-11-19,Measurement of spin waves and activation volumes in superparamagnetic Fe films on GaAs(100),"Spin wave frequencies are observed in ultra-thin Fe/GaAs(100) films at
+temperatures where the spontaneous zero field magnetization is zero. The films
+exhibit good cyrstalline structure, and the effect of magnetic anisotropies is
+apparent even though no zero field spin wave energy gap exists. An analysis is
+given in terms of a superparamagnetic model in which the film is treated as a
+network of non-interacting single domain magnetic islands. A spin wave analysis
+provides a means to separate measured values of anisotropy parameters from
+products involving anisotropy and island volume. In this way, a measure of the
+activation volume associated with superparamagnetic islands is obtained for
+different Fe film thicknesses. Results suggest that the island lateral area
+increases with increasing film thickness.",0511482v1
+2005-11-28,Basal-Plane Magnetic Anisotropies of High-kappa d-Wave Superconductors in a Mixed State: A Quasiclassical Approach,"We study the basal-plane anisotropies of reversible magnetization and torque
+in a mixed state of layered d-wave superconductors based on the quasiclassical
+version of the BCS-Gor'kov theory. Both the longitudinal magnetization ($M_L$)
+and torque ($\tau$) show fourfold oscillations as a function of the field angle
+$\chi$. The relationship between the node position and the oscillatory patterns
+shown by $M_L$ and $\tau$ is clarified. It is also shown that the sign of the
+$\tau (\chi)$-oscillation does not change between $H_{c1}$ and $H_{c2}$, while
+the sign of the $M_L (\chi)$-oscillation changes. The newly obtained result for
+$\tau$ indicates that the torque experiment can allow us to detect the in-plane
+anisotropies of $H_{c2}$ even in a material with strong fluctuations such as
+cuprate or organic superconductors, where the $H_{c2}$ itself cannot be
+determined experimentally.",0511644v2
+2005-12-18,Theory of the algebraic vortex liquid in an anisotropic spin-1/2 triangular antiferromagnet,"We explore spin-1/2 triangular antiferromagnets with both easy-plane and
+lattice exchange anisotropies by employing a dual vortex mapping followed by a
+fermionization of the vortices. Over a broad range of exchange anisotropy, this
+approach leads naturally to a ``critical'' spin liquid--the algebraic vortex
+liquid--which appears to be distinct from other known spin liquids. We present
+a detailed characterization of this state, which is described in terms of
+non-compact QED3 with an emergent SU(4) symmetry. Descendant phases of the
+algebraic vortex liquid are also explored, which include the Kalmeyer-Laughlin
+spin liquid, a variety of magnetically ordered states such as the well known
+coplanar spiral state, and supersolids. In the range of exchange anisotropy
+where the ``square lattice'' Neel ground state arises, we demonstrate that
+anomalous ``roton'' minima in the excitation spectrum recently reported in
+series expansions can be accounted for within our approach.",0512427v1
+2006-01-03,In-plane anisotropy of spin excitations in the normal and superconducting states of underdoped YBa$_2$Cu$_3$O$_{6+x}$,"A detailed inelastic neutron scattering study of the in-plane anisotropy of
+magnetic excitations in twin-free YBa$_2$Cu$_3$O$_{6.6}$ ($T_c =$ 61 K) reveals
+that the spin excitation spectra in the superconducting and normal states are
+qualitatively different. Below $T_c$, the spectrum consists of upward- and
+downward-dispersing branches with modest in-plane anisotropy merging at an
+energy $E_{res} =$ 37.5 meV. In the normal state, the singularity at $E_{res}$
+disappears, and the spectrum exhibits a steep dispersion with a strongly
+anisotropic in-plane geometry. These data have important implications for
+models based on static or dynamic ""stripe"" order of spins and charges.",0601048v2
+2006-01-12,Anomalous in-plane magneto-optical anisotropy of self-assembled quantum dots,"We report on a complex nontrivial behavior of the optical anisotropy of
+quantum dots that is induced by a magnetic field in the plane of the sample. We
+find that the optical axis either rotates in the opposite direction to that of
+the magnetic field or remains fixed to a given crystalline direction. A
+theoretical analysis based on the exciton pseudospin Hamiltonian unambiguously
+demonstrates that these effects are induced by isotropic and anisotropic
+contributions to the heavy-hole Zeeman term, respectively. The latter is shown
+to be compensated by a built-in uniaxial anisotropy in a magnetic field B_c =
+0.4 T, resulting in an optical response typical for symmetric quantum dots.",0601270v1
+2006-02-07,Tunable dipolar magnetism in high-spin molecular clusters,"We report on the Fe17 high-spin molecular cluster and show that this system
+is an exemplification of nanostructured dipolar magnetism. Each Fe17 molecule,
+with spin S=35/2 and axial anisotropy as small as D=-0.02K, is the magnetic
+unit that can be chemically arranged in different packing crystals whilst
+preserving both spin ground-state and anisotropy. For every configuration,
+molecular spins are correlated only by dipolar interactions. The ensuing
+interplay between dipolar energy and anisotropy gives rise to macroscopic
+behaviors ranging from superparamagnetism to long-range magnetic order at
+temperatures below 1K.",0602184v2
+2006-02-19,Origin of four-fold anisotropy in square lattices of circular ferromagnetic dots,"We discuss the four-fold anisotropy of in-plane ferromagnetic resonance (FMR)
+field $H_r$, found in a square lattice of circular Permalloy dots when the
+interdot distance $a$ gets comparable to the dot diameter $d$. The minimum
+$H_r$, along the lattice $<11>$ axes, and the maximum, along the $<10>$ axes,
+differ by $\sim$ 50 Oe at $a/d$ = 1.1. This anisotropy, not expected in
+uniformly magnetized dots, is explained by a non-uniform magnetization
+$\bm(\br)$ in a dot in response to dipolar forces in the patterned magnetic
+structure. It is well described by an iterative solution of a continuous
+variational procedure.",0602447v4
+2006-03-01,Correlation functions for the $XY$ model in a Magnetic Field,"Recent studies of the two-dimensional, classical $XY$ magnet in a magnetic
+field suggest that it has three distinct vortex phases: a linearly confined
+phase, a logarithmically confined phase, and a free vortex phase. In this work
+we study spin-spin correlation functions in this model by analytical analysis
+and numerical simulations to search for signatures of the various phases. In
+all three phases, the order parameter is nonzero and $<\cos(\th({\bf
+r}_1))\cos(\th({\bf r}_2))>$ remains nonzero for $r \equiv |{\bf r}_1-{\bf
+r}_2|\rightarrow \infty$, indicating the expected long range order. The
+correlation function for transverse fluctuations of the spins,
+$C(r)=<\sin(\th({\bf r}_1))\sin(\th({\bf r}_2))>$, falls exponentially in all
+three phases. A renormalization group analysis suggests that the
+logarithmically confined phase should have a spatially anisotropic correlation
+length. In addition, there is a generic anisotropy in the prefactor which is
+always present. We find that this prefactor anisotropy becomes rather strong in
+the presence of a magnetic field, masking the effects of any anisotropy in the
+correlation length in the simulations.",0603028v1
+2006-03-14,The effect of uniaxial crystal-field anisotropy on magnetic properties of the superexchange antiferromagnetic Ising model,"The generalized Fisher super-exchange antiferromagnetic model with uniaxial
+crystal-field anisotropy is exactly investigated using an extended mapping
+technique. An exact relation between partition function of the studied system
+and that one of the standard zero-field spin-1/2 Ising model on the
+corresponding lattice is obtained applying the decoration-iteration
+transformation. Consequently, exact results for all physical quantities are
+derived for arbitrary spin values S of decorating atoms. Particular attention
+is paid to the investigation of the effect of crystal-field anisotropy and
+external longitudinal magnetic field on magnetic properties of the system under
+investigation. The most interesting numerical results for ground-state and
+finite-temperature phase diagrams, thermal dependences of the sublattice
+magnetization and other thermodynamic quantities are discussed.",0603377v1
+2006-03-31,Large magnetic anisotropy in Ferrihydrite nanoparticles synthesized from reverse micelles,"Six-line ferrihydrite(FH) nanoparticles have been synthesized in the core of
+reverse micelles, used as nanoreactors to obtain average particle sizes $<d>$
+$\approx$ 2 to 4 nm. The blocking temperatures $T_B^m$ extracted from
+magnetization data increased from $\approx 10$ to 20 K for increasing particle
+size. Low-temperature \MOS measurements allowed to observe the onset of
+differentiated contributions from particle core and surface as the particle
+size increases. The magnetic properties measured in the liquid state of the
+original emulsion showed that the \FH phase is not present in the liquid
+precursor, but precipitates in the micelle cores after the free water is
+freeze-dried. Systematic susceptibility $\chi_{ac}(\emph{f},T)$ measurements
+showed the dependence of the effective magnetic anisotropy energies $E_{a}$
+with particle volume, and yielded an effective anisotropy value of $K_{eff} =
+312\pm10$ kJ/m$^3$.",0603852v2
+2006-05-04,Magnetic anisotropy of $Co_x Pt_{1-x}$ clusters embedded in matrix: Influences of the cluster chemical composition and the matrix nature,"We report on the magnetic properties of Co$\_x$Pt$\_{1-x}$ clusters embedded
+in various matrices. Using a careful analysis of magnetization curves and ZFC
+susceptibility measurements, we determine the clusters magnetic anisotropy
+energy (MAE) and separate the surface and volume contributions. By comparing
+different chemical compositions, we show that a small amount of Pt (15%)
+induces an important increase in the volume anisotropy with respect to pure Co
+clusters, even in chemically disordered fcc clusters. Comparing the
+measurements of clusters embedded in Nb and MgO matrices, we show that the
+oxide matrix induces an important increase of the surface MAE attributed to the
+formation of an antiferromagnetic CoO shell around the clusters.",0605107v1
+2006-06-21,Magnetic anisotropies and magnetization reversal of the Co$_2$Cr$_{0.6}$Fe$_{0.4}$Al Heusler compound,"Magnetic anisotropies and magnetization reversal properties of the epitaxial
+Heusler compound Co$_2$Cr$_{0.6}$Fe$_{0.4}$Al (CCFA) deposited on Fe and Cr
+buffer layers are studied. Both samples exhibit a growth-induced fourfold
+anisotropy, and magnetization reversal occurs through the formation of stripy
+domains or 90 degree domains. During rotational magnetometric scans the sample
+deposited on Cr exhibits about 2 degree sharp peaks in the angular dependence
+of the coercive field, which are oriented along the hard axis directions. These
+peaks are a consequence of the specific domain structure appearing in this
+particular measurement geometry. A corresponding feature in the sample
+deposited on Fe is not observed.",0606542v1
+2006-07-03,Dramatic role of critical current anisotropy on flux avalanches in MgB2 films,"Anisotropic penetration of magnetic flux in MgB2 films grown on vicinal
+sapphire substrates is investigated using magneto-optical imaging. Regular
+penetration above 10 K proceeds more easily along the substrate surface steps,
+anisotropy of the critical current being 6%. At lower temperatures the
+penetration occurs via abrupt dendritic avalanches that preferentially
+propagate {\em perpendicular} to the surface steps. This inverse anisotropy in
+the penetration pattern becomes dramatic very close to 10 K where all flux
+avalanches propagate in the strongest-pinning direction. The observed behavior
+is fully explained using a thermomagnetic model of the dendritic instability.",0607063v1
+2006-07-13,Spin-Reorientation Transition of Field-Induced Magnetic Ordering Phases in the Anisotropic Haldane System,"A possible spin-reorientation transition in field-induced magnetic ordering
+phases of the S=1 Haldane system with large easy-plane anisotropy is proposed,
+using an effective Lagrangian formalism as well as the density matrix
+renormalization group method. Such a spin-reorientation transition is predicted
+in the case where the applied magnetic field is inclined from the easy axis of
+the anisotropy. We point out that this transition has a close connection with a
+variation of the order parameter even at zero temperature, although it is
+different from a quantum analog of the so-called spin-flop transition proposed
+for the system having a strong easy axis anisotropy. In connection with a novel
+phase observed recently in the Haldane system at high fields, we discuss
+possible implications for the field-induced magnetic ordering.",0607336v1
+2006-07-26,Many-body Green's function theory of Heisenberg films,"The treatment of Heisenberg films with many-body Green's function theory
+(GFT) is reviewed. The basic equations of GFT are derived in sufficient detail
+so that the rest of the paper can be understood without having to consult
+further literature. The main part of the paper is concerned with applications
+of the formalism to ferromagnetic, antiferromagnetic and coupled
+ferromagnetic-antiferromagnetic Heisenberg films based on a generalized
+Tyablikov (RPA) decoupling of the exchange interaction and exchange anisotropy
+terms and an Anderson-Callen decoupling for a weak single-ion anisotropy. We
+not only give a consistent description of our own work but also refer
+extensively to related investigations. We discuss in particular the
+reorientation of the magnetization as a function of the temperature and film
+thickness. If the single-ion anisotropy is strong, it can be treated exactly by
+going to higher-order Green's functions. We also discuss the extension of the
+theory beyond RPA. Finally the limitations of GFT is pointed out.",0607675v1
+2006-12-13,Stability of Random-Field and Random-Anisotropy Fixed Points at large N,"In this note, we clarify the stability of the large-N functional RG fixed
+points of the order/disorder transition in the random-field (RF) and
+random-anisotropy (RA) O(N) models. We carefully distinguish between infinite
+N, and large but finite N. For infinite N, the Schwarz-Soffer inequality does
+not give a useful bound, and all fixed points found in cond-mat/0510344 (Phys.
+Rev. Lett. 96, 197202 (2006)) correspond to physical disorder. For large but
+finite N (i.e. to first order in 1/N) the non-analytic RF fixed point becomes
+unstable, and the disorder flows to an analytic fixed point characterized by
+dimensional reduction. However, for random anisotropy the fixed point remains
+non-analytic (i.e. exhibits a cusp) and is stable in the 1/N expansion, while
+the corresponding dimensional-reduction fixed point is unstable. In this case
+the Schwarz-Soffer inequality does not constrain the 2-point spin correlation.
+We compute the critical exponents of this new fixed point in a series in 1/N
+and to 2-loop order.",0612310v1
+2006-12-14,Stripes in thin ferromagnetic films with out-of-plane anisotropy,"We examine the T=0 phase diagram of a thin ferromagnetic film with a strong
+out-of-plane anisotropy in the vicinity of the reorientation phase transition
+(with Co on Pt as an example). The phase diagram in the anisotropy-applied
+field plane is universal in the limit where the film thickness is the shortest
+length scale. It contains uniform fully magnetized and canted phases, as well
+as periodically nonuniform states: a weakly modulated spin-density wave and
+strongly modulated stripes. We determine the boundaries of metastability of
+these phases and point out the existence of a critical point at which the
+difference between the SDW and stripes vanishes. Out-of-plane magnetization
+curves exhibit a variety of hysteresis loops caused by the coexistence of one
+or more phases. Additionally, we study the effect of a system edge on the
+orientation of stripes. We compare our results with recent experiments.",0612346v2
+2007-03-16,Nature of the Perpendicular-to-Parallel Spin Reorientation in a Mn-doped GaAs Quantum Well: Canting or Phase Separation?,"It is well known that the magnetic anisotropy in a compressively-strained
+Mn-doped GaAs film changes from perpendicular to parallel with increasing hole
+concentration $p$. We study this reorientation transition at T=0 in a quantum
+well with Mn impurities confined to a single plane. With increasing $p$, the
+angle $\theta $ that minimizes the energy $E$ increases continuously from 0
+(perpendicular anisotropy) to $\pi /2$ (parallel anisotropy) within some range
+of $p$. The shape of $\Emin (p)$ suggests that the quantum well becomes phase
+separated with regions containing low hole concentrations and perpendicular
+moments interspersed with other regions containing high hole concentrations and
+parallel moments. However, due to the Coulomb energy cost associated with phase
+separation, the true magnetic state in the transition region is canted with $0
+< \theta < \pi /2$.",0703436v1
+2007-03-28,Transverse ultrasound absorption in cubic crystals with positive and negative anisotropies of second-order elasticity moduli,"The transverse ultrasound absorption in cubic crystals with positive and
+negative anisotropies of the second-order elasticity moduli is analyzed. The
+scattering of the ultrasound by defects and during anharmonic scattering
+processes is considered. The transverse ultrasound absorption is analyzed as a
+function of the wave-vector direction in terms of the anisotropic continuum
+model. The Landau-Rumer mechanism is considered for anharmonic scattering
+processes. Known values of the second- and third-order elasticity moduli are
+used to calculate parameters determining the ultrasound absorption. It is shown
+that the angular dependences of the transverse ultrasound absorption differ
+qualitatively if the anharmonic scattering processes dominate in cubic crystals
+with positive and negative anisotropies of the second-order elasticity moduli.
+For the scattering by defects and the anharmonic scattering processes, the
+angular dependences of the transverse ultrasound absorption exhibit the inverse
+behavior, making it possible to determine the dominating mechanism of the
+ultrasound relaxation in the crystals under study.",0703748v1
+1998-02-19,Effects of anisotropy and spatial curvature on the pre-big bang scenario,"A class of exact, anisotropic cosmological solutions to the vacuum
+Brans-Dicke theory of gravity is considered within the context of the pre-big
+bang scenario. Included in this class are the Bianchi type III, V and VI_h
+models and the spatially isotropic, negatively curved
+Friedmann-Robertson-Walker universe. The effects of large anisotropy and
+spatial curvature are determined. In contrast to negatively curved
+Friedmann-Robertson-Walker model, there exist regions of the parameter space in
+which the combined effects of curvature and anisotropy prevent the occurrence
+of inflation. When inflation is possible, the necessary and sufficient
+conditions for successful pre-big bang inflation are more stringent than in the
+isotropic models. The initial state for these models is established and
+corresponds in general to a gravitational plane wave.",9802052v1
+1998-04-28,Seeds of large-scale anisotropy in string cosmology,"Pre-big bang cosmology predicts tiny first-order dilaton and metric
+perturbations at very large scales. Here we discuss the possibility that other
+-- more copiously generated -- perturbations may act, at second order, as
+scalar seeds of large-scale structure and CMB anisotropies. We study, in
+particular, the cases of electromagnetic and axionic seeds. We compute the
+stochastic fluctuations of their energy-momentum tensor and determine the
+resulting contributions to the multipole expansion of the temperature
+anisotropy. In the axion case it is possible to obtain a flat or slightly
+tilted blue spectrum that fits present data consistently, both for massless and
+for massive (but very light) axions.",9804076v1
+1998-06-18,Weighing the string mass with the COBE data,"In the context of the pre-big bang scenario the large-scale CMB anisotropy
+can be seeded by a primordial background of very light (or massless) axion
+fluctuations. In that case the slope of the temperature anisotropy spectrum,
+allowed by present observations, defines an allowed range of values for the
+string mass scale. Conversely, from the theoretical expected value of the
+string scale we can predict the slope of the anisotropy spectrum. In both cases
+there is a remarkable agreement between observations and theoretical
+expectations.",9806073v1
+1998-12-07,"Fully Anisotropic String Cosmologies, Maxwell Fields and Primordial Shear","We present a class of exact cosmological solutions of the low energy string
+effective action in the presence of a homogeneous magnetic fields. We discuss
+the physical properties of the obtained (fully anisotropic) cosmologies paying
+particular attention to their vacuum limit and to the possible isotropization
+mechanisms. We argue that quadratic curvature corrections are able to
+isotropize fully anisotropic solutions whose scale factors describe accelerated
+expansion. Moreover, the degree of isotropization grows with the duration of
+the string phase. We follow the fate of the shear parameter in a decelerated
+phase where, dilaton, magnetic fields and radiation fluid are simultaneously
+present. In the absence of any magnetic field a long string phase immediately
+followed by radiation is able to erase large anisotropies. Conversely, if a
+short string phase is followed by a long dilaton dominated phase the
+anisotropies can be present, in principle, also at later times. The presence of
+magnetic seeds after the end of the string phase can induce further
+anisotropies which can be studied within the formalism reported in this paper.",9812021v1
+2002-04-14,Radion and Large Scale Anisotropy on the Brane,"We investigate the effect of the radion on cosmological perturbations in the
+brane world. The S^1/Z_2 compactified 5D Anti-de Sitter spacetime bounded by
+positive and negative tension branes is considered. The radion is the relative
+displacement of the branes in this model. We find two different kinds of the
+radion at the linear perturbation order for a cosmological brane. One describes
+a ""fluctuation"" of the brane which does not couple to matter on the brane. The
+other describes a ""bend"" of the brane which couples to the matter. The bend
+determines the curvature perturbation on the brane. At large scales, the radion
+interacts with anisotopic perturbations in the bulk. By solving the bulk
+anisotropic perturbations, large scale metric perturbations and anisotropies of
+the Cosmic Microwave Background (CMB) on the positive tension brane are
+calculated. We find an interesting fact that the radion contributes to the CMB
+anisotropies. The observational consequences of these effects are discussed.",0204047v2
+2005-04-25,Acoustic peaks in the CMB: a matter of standard causal boundary conditions on primordial density anisotropies,"The pattern of acoustic peaks in the sub-horizon power spectrum of primordial
+density anisotropies at recombination can be naturally understood in the
+framework of standard Friedmann-Robertson-Walker cosmology (without inflation)
+as a consequence of the boundary conditions imposed by the causal horizon on
+the statistical two-points correlation functions: the sub-horizon spectrum is
+discrete (harmonic), with comoving modes located at $k_n = n
+\frac{\pi}{H^{-1}_{eq}}$, $n = 1,2,...$, because the causally connected patch
+of the universe at recombination is compact, with comoving radius
+$H^{-1}_{eq}$. The results presented in this paper complement those presented
+in [1], where it was shown that the scale invariance of the primordial density
+anisotropies over comoving scales of cosmological size is also a consequence of
+the boundary conditions imposed by causality. Together these results lay an
+appealing theoretical alternative to the inflationary paradigm as the ultimate
+answer for the origin of cosmological structures in standard cosmology.",0504124v1
+2006-12-24,Friedmann Robertson-Walker model in generalised metric space-time with weak anisotropy,"A generalized model of space-time is given, taking into consideration the
+anisotropic structure of fields which are depended on the position and the
+direction (velocity).In this framework a generalized FRW-metric the
+Raychaudhouri and Friedmann equations are studied.A long range vector field of
+cosmological origin is considered in relation to the physical geometry of
+space-time in which Cartan connection has a fundamental role.The generalised
+Friedmann equations are produced including anisotropic terms.The variation of
+anisotropy $z_t$ is expressed in terms of the Cartan torsion tensor of the
+Finslerian space-time.A possible estimation of the anisotropic parameter $z_t$
+can be achieved with the aid of the de-Sitter model of the empty flat universe
+with weak anisotropy. Finally a physical generalisation for the model of
+inflation is also studied.",0612157v4
+1996-06-13,Large Self-affine fractality in $\p^+$p and K$^+$p collisions at 250 GeV/$c$,"Taking into account the anisotropy of phase space in multiparticle
+production, a self-affine analysis of factorial moments was carried out on the
+NA22 data for $\p^+\Pp$ and $\PK^+\Pp$ collisions at 250 GeV/$c$. Within the
+transverse plane, the Hurst exponents measuring the anisotropy are consistent
+with unit value (i.e. no anisotropy). They are, however, only half that value
+when the longitudinal direction is compared to the transverse ones. Fractality,
+indeed, turns out to be self-affine rather than self-similar in multiparticle
+production. In three-dimensional phase space, power-law scaling is observed to
+be better realized in self-affine than in self-similar analysis.",9606005v1
+1992-07-31,A Lower Bound on $T_{SR}/{m_{\rm H}}$ in the O(4) Model on Anisotropic Lattices,"Results of an investigation of the $O(4)$ spin model at finite temperature
+using anisotropic lattices are presented. In both the large $N$ approximation
+and numerical simulations using the Wolff cluster algorithm we find that the
+ratio of the symmetry restoration temperature $T_{\rm SR}$ to the Higgs mass
+$m_{\rm H}$ is independent of the anisotropy $\xi$. From the numerical
+simulations we obtain a lower bound of $T_{\rm SR} / m_{\rm H} \simeq 0.58 \pm
+0.02$ at a value for the Higgs mass $m_{\rm H}a_s \simeq 0.5$, which is lowered
+further by about $10\%$ at $m_{\rm H}a_s \simeq 1$. Requiring certain timelike
+correlation functions to coincide with their spacelike counterparts, quantum
+and scaling corrections to the anisotropy are determined and are found to be
+small, i.e., the anisotropy is found to be close to the ratio of spacelike and
+timelike lattice spacings.",9207033v1
+1999-05-03,Determination of Anisotropy Coefficients for SU(3) Gauge Actions from the Integral and Matching Methods,"We use two non-perturbative methods to obtain the anisotropy derivatives of
+the coupling constants (the anisotropy coefficients) of SU(3) lattice gauge
+theory. These coefficients appear in the derivative formulae for the energy
+density and the pressure. We calculate them for the standard Wilson and two
+improved actions, the 2x2 and the Square Symanzik action. Both methods lead for
+all investigated actions to compatible results which are clearly different from
+their known asymptotic perturbative limits. With increasing beta the limits are
+however approached in all cases. Our findings strongly support the equivalence
+of the integral and derivative methods for the calculation of energy density
+and pressure.",9905002v1
+2001-05-31,Perfect Gauge Actions on Anisotropic Lattices,"We present a method for constructing classically perfect anisotropic actions
+for SU(3) gauge theory based on a present isotropic Fixed Point Action. The
+action is parametrised using smeared (``fat'') links. The construction is done
+explicitly for anisotropy $\xi=a_s/a_t=2,4$ and the renormalised anisotropies
+are determined using the torelon dispersion relation. Quantities such as the
+static quark-antiquark potential, the critical temperature of the deconfining
+phase transition and the low-lying glueball spectrum are measured as well. It
+turns out that the procedure presented works, the renormalised anisotropy is
+small and the parametrisation describes the full action well. Issues such as
+the application of the method for scalar fields as well as for the quadratic
+approximation to gauge theory, measurements of autocorrelation times of simple
+operators and of the computational overhead are also covered. A (more compact)
+paper about this classically perfect anisotropic gauge action is in
+preparation.",0105033v1
+2002-03-24,Heavy quark action on the anisotropic lattice,"We investigate the $O(a)$ improved quark action on anisotropic lattice as a
+potential framework for the heavy quark, which may enable precision computation
+of hadronic matrix elements of heavy-light mesons. The relativity relations of
+heavy-light mesons as well as of heavy quarkonium are examined on a quenched
+lattice with spatial lattice cutoff $a_\sigma^{-1} \simeq$ 1.6 GeV and the
+anisotropy $\xi=4$. We find that the bare anisotropy parameter tuned for the
+massless quark describes both the heavy-heavy and heavy-light mesons within 2%
+accuracy for the quark mass $a_\sigma m_Q < 0.8$, which covers the charm quark
+mass. This bare anisotropy parameter also successfully describes the
+heavy-light mesons in the quark mass region $a_\sigma m_Q \leq 1.2$ within the
+same accuracy. Beyond this region, the discretization effects seem to grow
+gradually. The anisotropic lattice is expected to extend by a factor $\xi$ the
+quark mass region in which the parameters in the action tuned for the massless
+limit are applicable for heavy-light systems with well controlled systematic
+errors.",0203025v1
+2003-03-18,Renormalization of Anisotropy and Glueball Masses on Tadpole Improved Lattice Gauge Action,"The Numerical calculations for tadpole-improved U(1) lattice gauge theory in
+three-dimensions on anisotropic lattices have been performed using standard
+path integral Monte Carlo techniques. Using average plaquette tadpole
+renormalization scheme, simulations were done with temporal lattice spacings
+much smaller than the spatial ones and results were obtained for the string
+tension, the renormalized anisotropy and scalar glueball masses. We find, by
+comparing the `regular' and `sideways' potentials, that tadpole improvement
+results in very little renormalization of the bare anisotropy and reduces the
+discretization errors in the static quark potential and in the glueball masses.",0303011v3
+2003-07-08,"The contribution of O(alpha) radiative corrections to the renormalised anisotropy and application to general tadpole improvement schemes: addendum to ""One loop calculation of the renormalised anisotropy for improved anisotropic gluon actions on a lattice"" [hep-lat/0208010]","General O(alpha) radiative corrections to lattice actions may be interpreted
+as counterterms that give additive contributions to the one-loop
+renormalisation of the anisotropy. The effect of changing the radiative
+coefficients is thus easily calculable. In particular, the results obtained in
+a previous paper for Landau mean link improved actions apply in any tadpole
+improvement scheme. We explain how this method can be exploited when tuning
+radiatively improved actions. Efficient methods for self-consistently tuning
+tadpole improvement factors are also discussed.",0307010v1
+1992-05-08,"Grand Unification, Gravitational Waves, and the Cosmic Microwave Background Anisotropy","We re-examine the gravitational wave background resulting from inflation and
+its effect on the cosmic microwave background radiation. The new COBE
+measurement of a cosmic background quadrupole anisotropy places an upper limit
+on the vacuum energy during inflation of $\approx 5 \times 10^{16}$ GeV. A
+stochastic background of gravitational waves from inflation could produce the
+entire observed signal (consistent with the observed dipole anisotropy and a
+flat spectrum) if the vacuum energy during inflation was as small as $1.5
+\times 10^{16}$ GeV at the 95\% confidence level. This coincides nicely with
+the mass scale for Grand Unification inferred from precision measurements of
+the electroweak and strong coupling constants, for the SUSY Grand Unified
+Theories. Thus COBE could be providing the first direct evidence, via
+gravitational waves, for GUTs, and supersymmetry. Further tests of this
+possibility are examined, based on analyzing the energy density associated with
+gravitational waves from inflation.",9205212v1
+1992-08-07,The gravitational wave contribution to CMB anisotropies and the amplitude of mass fluctuations from COBE results,"A stochastic background of primordial gravitational waves may substantially
+contribute, via the Sachs--Wolfe effect, to the large--scale Cosmic Microwave
+Background (CMB) anisotropies recently detected by COBE. This implies a {\it
+bias} in any resulting determination of the primordial amplitude of density
+fluctuations. We consider the constraints imposed on $n<1$ (``tilted"")
+power--law fluctuation spectra, taking into account the contribution from both
+scalar and tensor waves, as predicted by power--law inflation. The
+gravitational--wave contribution to CMB anisotropies generally reduces the
+required {\it rms} level of mass fluctuation, thereby increasing the linear
+{\it bias parameter}, even in models where the spectral index is close to the
+Harrison--Zel'dovich value $n=1$. This ``gravitational--wave bias"" helps to
+reconcile the predictions of CDM models with observations on pairwise galaxy
+velocity dispersion on small scales.",9208214v1
+1992-08-10,"Density Perturbations,Gravity Waves and the Cosmic Microwave Background","We asses the contribution to the observed large scale anisotropy of the
+cosmic microwave background radiation, arising from both gravity waves as well
+as adiabatic density perturbations, generated by a common inflationary
+mechanism in the early Universe.
+  We find that for inflationary models predicting power law primordial spectra
+%$a(t) \propto t^p, p > 1$, $\dk^2 \propto k^n$, the relative contribution to
+the quadrupole anisotropy from gravity waves and scalar density perturbations,
+depends crucially upon $n$. For $n < 0.87$, gravity waves perturb the CMBR by a
+larger amount than density perturbations, whereas for $n > 0.87$ the reverse is
+true. %For nearly exponential inflation, on the other hand, the contribution to
+the %microwave anisotropy from scalar density perturbations always exceeds
+%that due to gravity waves. Normalising the amplitude of the density
+perturbation spectrum at large scales, using the observed value of the COBE
+quadrupole, we determine $(\delta M /M)_{16}$ -- the rms density contrast on
+scales $\sim 16 h_{50}^{-1}$ Mpc, for cosmological models with cold dark
+matter. We find that for $n < 0.75$, a large amount of biasing is required in
+order to reconcile theory with observations.",9208217v1
+1993-10-20,$Π$ in the Sky ? Microwave Anisotropies from Cosmic Defects,"High resolution maps of the anisotropy of the microwave sky will yield
+invaluable clues as to the mechanisms involved in cosmic structure formation.
+One fundamental question they should answer is whether the fluctuations were
+Gaussian random noise, as predicted in inflationary models, or were nonGaussian
+as in theories based on symmetry breaking and cosmic defects. In the latter
+case there is the prospect of obtaining information regarding symmetry breaking
+at high energy scales, specifically the homotopy classes $\Pi_n$ of the vacuum
+manifold. In this paper we report on detailed calculations of the degree scale
+anisotropies predicted in the cosmic string, monopole texture and
+nontopological texture theories of structure formation, emphasising their
+distinct character from those predicted by inflation, and the bright prospects
+for experimental tests.",9310322v2
+1998-12-31,Microwave background anisotropies in quasiopen inflation,"Quasiopenness seems to be generic to multi-field models of single-bubble open
+inflation. Instead of producing infinite open universes, these models actually
+produce an ensemble of very large but finite inflating islands. In this paper
+we study the possible constraints from CMB anisotropies on existing models of
+open inflation. The effect of supercurvature anisotropies combined with the
+quasiopenness of the inflating regions make some models incompatible with
+observations, and severely reduces the parameter space of others. Supernatural
+open inflation and the uncoupled two-field model seem to be ruled out due to
+these constraints for values of $\Omega_0\lesssim0.98$. Others, such as the
+open hybrid inflation model with suitable parameters for the slow roll
+potential can be made compatible with observations.",9812533v1
+1999-03-23,Measuring the cosmological lepton asymmetry through the CMB anisotropy,"A large lepton asymmetry in the Universe is still a viable possibility and
+leads to many interesting phenomena such as gauge symmetry nonrestoration at
+high temperature. We show that a large lepton asymmetry changes the predicted
+cosmic microwave background (CMB) anisotropy and that any degeneracy in the
+relic neutrino sea will be measured to a precision of 1% or better when the CMB
+anisotropy is measured at the accuracy expected to result from the planned
+satellite missions MAP and Planck. In fact, the current measurements already
+put an upper limit on the lepton asymmetry of the Universe which is stronger
+than the one coming from considerations of primordial nucleosynthesis and
+structure formation.",9903459v3
+2000-10-18,Constraints on Natural Inflation from Cosmic Microwave Background,"We study constraints on the natural inflation model from the cosmic microwave
+background radiation (CMBR). Inflaton \phi for the natural inflation has a
+potential of the form V=\Lambda^4[1-\cos(\phi/\sqrt{2}f_\phi)], which is
+parametrized by two parameters f_\phi and \Lambda. Various cosmological
+quantities, like the primordial curvature perturbation and the CMBR anisotropy,
+are determined as functions of these two parameters. Using recent observations
+of the CMBR anisotropy by BOOMERANG and MAXIMA (as well as those from COBE),
+constraints on the parameters f_\phi and \Lambda are derived. The model with
+f_\phi lower than 8.5\times 10^{18} (5.4\times 10^{18}, 4.5\times 10^{18}) GeV
+predicts a power spectrum with index n_{\rm S} smaller than 0.95 (0.9, 0.85)
+which suppresses the CMBR anisotropy for smaller angular scale. With such a
+small n_{\rm S}, height of the second acoustic peak can become significantly
+lower than the case of the scale-invariant Harrison-Zeldovich spectrum.",0010197v2
+2001-12-27,Cosmic Microwave Background Anisotropy with Late Time Entropy Production,"We discuss effects of cosmological moduli fields on the cosmic microwave
+background (CMB). If a modulus field \phi once dominates the universe, the CMB
+we observe today is from the decay of \phi and its anisotropy is affected by
+the primordial fluctuation in the amplitude of the modulus field. As a result,
+constraints on the inflaton potential from the CMB anisotropy can be relaxed.
+In addition, with the cosmological moduli fields, correlated mixture of
+adiabatic and isocurvature fluctuations may be generated, which results in
+enhanced CMB angular power spectrum at higher multipoles relative to that of
+lower ones. Such an enhancement can be an evidence of late time entropy
+production due to the cosmological moduli fields, and may be observed at
+on-going and future experiments.",0112335v1
+2003-11-14,Narrowing the window for millicharged particles by CMB anisotropy,"We calculate the cosmic microwave background (CMB) anisotropy spectrum in
+models with millicharged particles of electric charge q\sim 10^{-6}-10^{-1} in
+units of electron charge. We find that a large region of the parameter space
+for the millicharged particles exists where their effect on the CMB spectrum is
+similar to the effect of baryons. Using WMAP data on the CMB anisotropy and
+assuming Big Bang nucleosynthesis value for the baryon abundance we find that
+only a small fraction of cold dark matter, Omega_{mcp}h_0^2 < 0.007 (at 95%
+CL), may consists of millicharged particles with the parameters (charge and
+mass) from this region. This bound significantly narrows the allowed range of
+the parameters of millicharged particles. In models without paraphoton
+millicharged particles are now excluded as a dark matter candidate. We also
+speculate that recent observation of 511 keV gamma-rays from the Galactic bulge
+may be an indication that a (small) fraction of CDM is comprised of the
+millicharged particles.",0311189v2
+2003-07-02,Super Heavy Dark Matter Anisotropies from D-particles in the Early Universe,"We discuss a way of producing anisotropies in the spectrum of superheavy Dark
+matter, which are due to the distortion of the inflationary space time induced
+by the recoil of D-particles upon their scattering with ordinary string matter
+in the Early Universe. We calculate such distortions by world-sheet Liouville
+string theory (perturbative) methods. The resulting anisotropies are found to
+be proportional to the average recoil velocity and density of the D-particles.
+In our analysis we employ a regulated version of de Sitter space, allowing for
+graceful exit from inflation. This guarantees the asymptotic flatness of the
+space time, as required for a consistent interpretation, within an effective
+field theory context, of the associated Bogolubov coefficients as particle
+number densities. The latter are computed by standard WKB methods.",0307028v1
+2004-01-28,Parity-violating Kalb-Ramond-Maxwell interactions and CMB anisotropy in a braneworld,"Following up on a recent paper by two of us (DM and SS), demonstrating the
+large enhancement in observable optical activity in radiation from high
+redshift sources arising from the string-based coupling of bulk Kalb-Ramond
+field to the Maxwell Chern Simons three-form on the brane in a Randall-Sundrum
+braneworld, we exhibit here a similar enhancement in parity-violating
+temperature-polarization correlations, yet unseen, in the CMB anisotropy due to
+a generalized parity-violating Kalb-Ramond axion-photon interaction proposed
+earlier by one of us (PM). The non-observation of such correlations in CMB
+anisotropies would necessitate unnatural fine tuning of the Kalb-Ramond axion
+parameters. As a stringy realization of Randall-Sundrum braneworld scenario is
+yet to be understood properly, our work indicates the need of a careful
+investigation to establish the connection between string-based phenomenological
+models and the Randall-Sundrum braneworld scenario",0401218v2
+2001-01-29,Stability of scaling regimes in $d\geq 2$ developed turbulence with weak anisotropy,"The fully developed turbulence with weak anisotropy is investigated by means
+of renormalization group approach (RG) and double expansion regularization for
+dimensions $d\ge 2$. Some modification of the standard minimal substraction
+scheme has been used to analyze stability of the Kolmogorov scaling regime
+which is governed by the renormalization group fixed point. This fixed point is
+unstable at $d=2$; thus, the infinitesimally weak anisotropy destroyes above
+scaling regime in two-dimensional space. The restoration of the stability of
+this fixed point, under transition from $d=2$ to $d=3,$ has been demonstrated
+at borderline dimension $ 2<d_c<3$. The results are in qualitative agreement
+with ones obtained recently in the framework of the usual analytical
+regularization scheme.",0101050v1
+2001-04-05,"Anomalous scaling, nonlocality and anisotropy in a model of the passively advected vector field","A model of the passive vector quantity advected by a Gaussian
+time-decorrelated self-similar velocity field is studied; the effects of
+pressure and large-scale anisotropy are discussed. The inertial-range behavior
+of the pair correlation function is described by an infinite family of scaling
+exponents, which satisfy exact transcendental equations derived explicitly in d
+dimensions. The exponents are organized in a hierarchical order according to
+their degree of anisotropy, with the spectrum unbounded from above and the
+leading exponent coming from the isotropic sector. For the higher-order
+structure functions, the anomalous scaling behavior is a consequence of the
+existence in the corresponding operator product expansions of ``dangerous''
+composite operators, whose negative critical dimensions determine the
+exponents. A close formal resemblance of the model with the stirred NS equation
+reveals itself in the mixing of operators. Using the RG, the anomalous
+exponents are calculated in the one-loop approximation for the even structure
+functions up to the twelfth order.",0104012v1
+2006-11-30,Influence of anisotropy and compressibility on anomalous scaling of a passive scalar field,"Influence of uniaxial small-scale anisotropy and compressibility on the
+stability of scaling regime and on the anomalous scaling of structure functions
+of a scalar field is investigated in the model of a passive scalar field
+advected by the compressible Gaussian strongly anisotropic velocity field with
+the covariance $\propto \delta(t-t^{\prime})|{\bf x}-{\bf
+x^{\prime}}|^{2\epsilon}$ by using the field theoretic renormalization group
+and the operator product expansion. The inertial-range stability of the
+corresponding scaling regime is established. The anomalous scaling of the
+single-time structure functions is studied and the corresponding anomalous
+exponents are calculated. Their dependence on the compressibility parameter and
+anisotropy parameters is analyzed. It is shown that the presence of
+compressibility leads to the decreasing of the critical dimensions of the
+important composite operators, i.e., the anomalous scaling is more pronounced
+in the compressible systems. This result is demonstrated for the structure
+function of the third order. All calculations are done to the first order in
+$\epsilon$.",0611061v1
+1996-10-18,Energy and Charged Particle Flow in 10.8 A GeV/c Au+Au Collisions,"Experimental results and a detailed analysis are presented of the transverse
+energy and charged particle azimuthal distributions measured by the E877
+collaboration for different centralities of Au+Au collisions at a beam momentum
+of 10.8 A GeV/c. The anisotropy of these distributions is studied with respect
+to the reaction plane reconstructed on an event-by-event basis using the
+transverse energy distribution measured by calorimeters. Results are corrected
+for the reaction plane resolution. For semicentral events we observe directed
+flow signals of up to ten percent. We observe a stronger anisotropy for slow
+charged particles. For both the charged particle and transverse energy
+distributions we observe a small but non zero elliptic anisotropy with the
+major axis pointing into the reaction plane. Combining the information on
+transverse energy and charged particle flow we obtain information on the flow
+of nucleons and pions. The data are compared to event generators and the need
+to introduce a mean field or nucleon-nucleon potential is discussed.",9610006v1
+2002-05-29,Pseudorapidity and centrality dependence of the collective flow of charged particles in Au+Au collisions at sqrt{s_NN} = 130 GeV,"This paper describes the measurement of collective flow for charged particles
+in Au+Au collisions at sqrt{s_NN}} = 130 GeV using the PHOBOS detector at the
+Relativistic Heavy Ion Collider (RHIC). An azimuthal anisotropy is observed in
+the charged particle hit distribution in the PHOBOS multiplicity detector. This
+anisotropy is presented over a wide range of pseudorapidity (eta) for the first
+time at this energy. The size of the anisotropy (v_{2}) is thought to probe the
+degree of equilibration achieved in these collisions. The result here,averaged
+over momenta and particle species, is observed to reach 7% for peripheral
+collisions at mid-rapidity, falling off with centrality and increasing |eta|.
+Data are presented as a function of centrality for |eta|<1.0 and as a function
+of eta, averaged over centrality, in the angular region -5.0<eta<5.3. These
+results call into question the common assumption of longitudinal boost
+invariance over a large region of rapidity in RHIC collisions.",0205021v1
+2004-11-19,Saturation of azimuthal anisotropy in Au + Au collisions at sqrt(s_NN) = 62 - 200 GeV,"New measurements are presented for charged hadron azimuthal correlations at
+mid-rapidity in Au+Au collisions at sqrt(s_NN) = 62.4 and 200 GeV. They are
+compared to earlier measurements obtained at sqrt(s_NN) = 130 GeV and in Pb+Pb
+collisions at sqrt(s_NN) = 17.2 GeV. Sizeable anisotropies are observed with
+centrality and transverse momentum (p_T) dependence characteristic of elliptic
+flow (v_2). For a broad range of centralities, the observed magnitudes and
+trends of the differential anisotropy, v_2(p_T), change very little over the
+collision energy range sqrt(s_NN) = 62-200 GeV, indicating saturation of the
+excitation function for v_2 at these energies. Such a saturation may be
+indicative of the dominance of a very soft equation of state for sqrt(s_NN) =
+62-200 GeV.",0411040v1
+1993-04-13,Maximum Azimuthal Anisotropy of Neutrons from Nb-Nb Collisions at 400 AMeV and the Nuclear Equation of State,"We measured the first azimuthal distributions of triple--differential cross
+sections of neutrons emitted in heavy-ion collisions, and compared their
+maximum azimuthal anisotropy ratios with Boltzmann--Uehling--Uhlenbeck (BUU)
+calculations with a momentum-dependent interaction. The BUU calculations agree
+with the triple- and double-differential cross sections for positive rapidity
+neutrons emitted at polar angles from 7 to 27 degrees; however, the maximum
+azimuthal anisotropy ratio for these free neutrons is insensitive to the size
+of the nuclear incompressibility modulus K characterizing the nuclear matter
+equation of state.",9304009v1
+1995-08-27,Decay Anisotropy of $e^+e^-$ Sources from $pN$ and $pd$ collisions,"A full calculation of lepton-pair angular characteristics is carried out for
+$e^+e^-$ pairs created in $pp$, $pn$ and $pd$ collisions at intermediate
+energies. It is demonstrated that the proposed new observable, the dilepton
+decay anisotropy, quite sensitively changes for different sources and may be
+useful for their disentangling. The relevance of the dilepton decay anisotropy
+is shown in the context of a puzzling energy behavior for the ratio of the
+lepton yield from $pd$ to $pp$ reactions as observed at the BEVALAC.",9508043v1
+1999-12-17,A Model of Convergent Extension in Animal Morphogenesis,"In this paper we argue that the pattern of cell movements in the
+morphogenetic process known as convergent extension can be understood as a
+energy minimization process, provided the cell-cell adhesive energy has a
+certain kind of anisotropy. This single simple property is sufficient cause for
+the type of cell elongation, alignment, and intercalation of a cellular array
+that is the characteristic of convergent extension. We describe the type of
+anisotropy required. We show that the final aspect ratio of the array of cells
+is independent of the initial configuration and of the degree of cell
+elongation. We find how it depends on the anisotropy.",9912038v3
+2001-06-14,Influence of Static and Dynamic Disorder on the Anisotropy of Emission in the Ring Antenna Subunits of Purple Bacteria Photosynthetic Systems,"Using the reduced density matrix formalism the time dependence of the exciton
+scattering in light-harvesting ring systems of purple bacteria is calculated.
+In contrast to the work of Kumble and Hochstrasser (J. Chem. Phys. 109 (1998)
+855) static disorder (fluctuations of the site energies) as well as dynamic
+disorder (dissipation) is taken into account. For the description of
+dissipation we use Redfield theory in exciton eigenstates without secular
+approximation. This is shown to be equivalent to the Markovian limit of Capek's
+theory in local states. Circular aggregates with 18 pigments are studied to
+model the B850 ring of bacteriochlorophyls within LH2 complexes. It can be
+demonstrated that the dissipation is important for the time-dependent
+anisotropy of the fluorescence. Smaller values of static disorder are
+sufficient to produce the same decay rates in the anisotropy in comparison with
+the results by Kumble and Hochstrasser.",0106043v1
+2002-08-23,Reinterpretation of Matter-Wave Interference Experiments Based on the Local-Ether Wave Equation,"Based on the local-ether wave equation for free particle, the dispersion of
+matter wave is examined. From the dispersion relation, the angular frequency
+and wavelength of matter wave are derived. These formulas look like the
+postulates of de Broglie in conjunction with the Lorentz mass-variation law.
+However, the fundamental difference is that for terrestrial particles their
+speeds are referred specifically to a geocentric inertial frame and hence
+incorporate the speed due to earth's rotation. Thus the local-ether model
+predicts an east-west directional anisotropy both in mass and wavelength.
+Meanwhile, in spite of the restriction on reference frame, the local-ether
+model can account for the matter-wave interference experiments of the Bragg
+reflection and the Sagnac effect. For electron wave, the effects of earth's
+rotation are negligible and the derived Bragg angle is actually in accord with
+the Davisson-Germer experiment, as examined within the present precision. On
+the other hand, the local-ether model leads to a directional anisotropy in the
+Bragg angle in neutron diffraction. The predicted anisotropy due to earth's
+rotation then provide a means to test the local-ether wave equation.",0208085v1
+2003-02-26,A New Limit on Signals of Lorentz Violation in Electrodynamics,"We describe the results of an experiment to test for spacetime anisotropy
+terms that might exist from Lorentz violations. The apparatus consists of a
+pair of cylindrical superconducting cavity-stabilized oscillators operating in
+the TM_{010} mode with one axis east-west and the other vertical. Spatial
+anisotropy is detected by monitoring the beat frequency at the sidereal rate
+and its first harmonic. We see no anisotropy to a part in 10^{13}. This puts a
+comparable bound on four linear combinations of parameters in the general
+Standard Model extension, and a weaker bound of <4 x 10^{-9} on three others.",0302093v1
+2004-07-19,Sharp vorticity gradients in two-dimensional hydrodynamic turbulence,"The appearance of sharp vorticity gradients in two-dimensional hydrodynamic
+turbulence and their influence on the turbulent spectra is considered. We have
+developed the analog of the vortex line representation as a transformation to
+the curvilinear system of coordinates moving together with the di-vorticity
+lines. Compressibility of this mapping can be considered as the main reason for
+the formation of the vorticity discontinuities at high Reynolds numbers. For
+two-dimensional turbulence in the case of strong anisotropy the vorticity
+discontinuities can generate spectra with the fall-off at large $k$
+proportional to $k^{-3}$ resembling the Kraichnan spectrum for the enstrophy
+cascade. For turbulence with weak anisotropy the $k$ dependence of the spectrum
+due to discontinuities coincides with that of the Saffman spectrum: $k^{-4}$.
+We have compared the analytical predictions with direct numerical solutions of
+the two-dimensional Euler equation for decaying turbulence. We observe that the
+di-vorticity is reaching very high values and is distributed locally in space
+along piecewise straight lines. Thus, indicating strong anisotropy and
+accordingly we found a spectrum close to the $k^{-3}$-spectrum.",0407101v1
+2004-07-25,Theory of electrical conductivities of ferrogels,"Conductive organic polymers can be formulated with polymers that incorporate
+fine dispersed metallic particles.
+  In this work, we present a general model for ferrogels which are chemically
+cross-linked polymer networks swollen with a ferrofluid. Our aim is to study
+the effect of the shape and/or material (conductivity) anisotropy on the
+effective electrical conductivity of the ferrogel in the presence of an
+external magnetic field. Our theory can reproduce the known results, and
+provides a link between the particle property and orientation distribution and
+the effective electrical conductivity. To this end, we find that material
+(conductivity) anisotropies are more important to yield a high effective
+electrical conductivity than shape anisotropies, while magnetic fields can
+offer a correction.",0407129v2
+2005-06-23,Gigantic transmission band edge resonance in periodic stacks of anisotropic layers,"We consider Fabry-Perot cavity resonance in periodic stacks of anisotropic
+layers with misaligned in-plane anisotropy at the frequency close to a photonic
+band edge. We show that in-plane dielectric anisotropy can result in a dramatic
+increase in field intensity and group delay associated with the transmission
+resonance. The field enhancement appears to be proportional to forth degree of
+the number N of layers in the stack. By contrast, in common periodic stacks of
+isotropic layers, those effects are much weaker and proportional to N^2. Thus,
+the anisotropy allows to drastically reduce the size of the resonance cavity
+with similar performance. The key characteristic of the periodic arrays with
+the gigantic transmission resonance is that the dispersion curve omega(k)at the
+photonic band edge has the degenerate form Delta(omega) ~ Delta(k)^4, rather
+than the regular form Delta(omega) ~ Delta(k)^2. This can be realized in
+specially arranged stacks of misaligned anisotropic layers. The degenerate band
+edge cavity resonance with similar outstanding properties can also be realized
+in a waveguide environment, as well as in a linear array of coupled multimode
+resonators, provided that certain symmetry conditions are in place.",0506174v1
+2004-08-09,Effects of the interplay between interaction and disorder in bipartite entanglement,"We use a disordered anti-ferromagnetic spin-1/2 chain with anisotropic
+exchange coupling to model an array of interacting qubits. All qubits have the
+same level spacing, except two, which are called the defects of the chain. The
+level spacings of the defects are equal and much larger than all the others. We
+investigate how the entanglement between the two defects depends on the
+anisotropy of the system. When the anisotropy coupling is much larger than the
+energy difference between a defect and an ordinary qubit, the two defects
+become strongly entangled. Small anisotropies, on the contrary, may decrease
+the entanglement, which is, in this case, also much affected by the number of
+excitations. The analysis is made for nearest neighbor and next-nearest
+neighbor defects. The decrease in the entanglement for nearest neighbor defects
+is not very significant, especially in large chains.",0408062v2
+2007-04-15,Interplay of Anisotropy and Disorder in the Doping-Dependent Melting and Glass Transitions of Vortices in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$,"We study the oxygen doping dependence of the equilibrium first-order melting
+and second-order glass transitions of vortices in
+Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. Doping affects both anisotropy and
+disorder. Anisotropy scaling is shown to collapse the melting lines only where
+thermal fluctuations are dominant. Yet, in the region where disorder breaks
+that scaling, the glass lines are still collapsed. A quantitative fit to
+melting and replica symmetry breaking lines of a 2D Ginzburg-Landau model
+further reveals that disorder amplitude weakens with doping, but to a lesser
+degree than thermal fluctuations, enhancing the relative role of disorder.",0704.1902v1
+2007-04-17,Effects of a pre-inflation radiation-dominated epoch to CMB anisotropy,"We consider that the pre-inflation era is radiation-dominated, transiting
+smoothly to the inflationary era. We work out in detail the dynamics of
+inflaton fluctuations across the phase transition and the proper choices of
+initial vacuum states. It is found that this phase transition can suppress
+long-wavelength quantum fluctuations of inflaton. This may attribute to the
+large-scale CMB anisotropy a lower power than predicted in the standard
+$\Lambda$CDM model. In constraining this transitional effect by WMAP anisotropy
+data, we use the WMAP best-fit scale-invariant $\Lambda$CDM model with the
+density power spectrum replaced by the one found in this work. We find that the
+transition occurs at least about 10 e-folds before the comoving scales
+comparable to our present horizon size cross the Hubble radius during
+inflation.",0704.2095v3
+2007-05-02,Effect of temperature-dependent shape anisotropy on coercivity with aligned Stoner-Wohlfarth soft ferromagnets,"The temperature variation effect of shape anisotropy on the coercivity,
+HC(T), for the aligned Stoner-Wohlfarth (SW) soft ferromagnets, such as fcc Ni,
+fcc Co and bcc Fe, are investigated within the framework of Neel-Brown (N-B)
+analysis. An extended N-B equation is thus proposed,by introducing a single
+dimensionless correction function, the reduced magnetization, m(\tao) =
+MS(T)/MS(0), in which \tao = T/TC is the reduced temperature, MS(T) is the
+saturation magnetization, and TC is the Curie temperature. The factor, m(\tao),
+accounts for the temperature-dependent effect of the shape anisotropy. The
+constants, H0 and E0, are for the switching field at zero temperature and the
+potential barrier at zero field, respectively. According to this newly derived
+equation, the blocking temperature above which the properties of
+superparamagnetism show up is described by the expression, TB =
+E0m^2(\tao)/[kBln(t/t0)], with the extra correction factor m^2(\tao). The
+possible effect on HC(T) and the blocking temperature, TB, attributed to the
+downshift of TC resulting from the finite size effect has been discussed also.",0705.0195v1
+2007-05-17,Kagome lattice antiferromagnets and Dzyaloshinsky-Moriya interactions,"We study the consequences of in-plane (D_p) and out-of-plane (D_z)
+Dzyaloshinsky-Moriya (DM) interactions on the thermodynamic properties of
+spin-1/2} Heisenberg model on the kagome lattice using numerical linked cluster
+expansions and exact diagonalization, and contrast them with those of other
+perturbations such as exchange anisotropy and dilution. We find that different
+combinations of the DM anisotropies lead to a wide variety of thermodynamic
+behavior, which are quite distinct from those of most other perturbations. We
+argue that the sudden upturn seen experimentally in the susceptibility of the
+material ZnCu3(OH)6Cl2 can be understood in terms of Dzyaloshinsky-Moriya
+anisotropies with D_p>|D_z|. We also show that the measured specific heat of
+the material puts further constraints on the allowed DM parameters.",0705.2591v2
+2007-05-24,Nonequilibrium Dynamics of Anisotropic Large Spins in the Kondo Regime: Time-Dependent Numerical Renormalization Group Analysis,"We investigate the time-dependent Kondo effect in a single-molecule magnet
+(SMM) strongly coupled to metallic electrodes. Describing the SMM by a Kondo
+model with large spin S > 1/2, we analyze the underscreening of the local
+moment and the effect of anisotropy terms on the relaxation dynamics of the
+magnetization. Underscreening by single-channel Kondo processes leads to a
+logarithmically slow relaxation, while finite uniaxial anisotropy causes a
+saturation of the SMM's magnetization. Additional transverse anisotropy terms
+induce quantum spin tunneling and a pseudospin-1/2 Kondo effect sensitive to
+the spin parity.",0705.3654v2
+2007-05-25,Probing polarization states of primordial gravitational waves with CMB anisotropies,"We discuss the polarization signature of primordial gravitational waves
+imprinted in cosmic microwave background (CMB) anisotropies. The high-energy
+physics motivated by superstring theory or M-theory generically yield parity
+violating terms, which may produce a circularly polarized gravitational wave
+background (GWB) during inflation. In contrast to the standard prediction of
+inflation with un-polarized GWB, circularly polarized GWB generates
+non-vanishing TB and EB-mode power spectra of CMB anisotropies. We evaluate the
+TB and EB-mode power spectra taking into account the secondary effects and
+investigate the dependence of cosmological parameters. We then discuss current
+constraints on the circularly polarized GWB from large angular scales (l < 16)
+of the three year WMAP data. Prospects for future CMB experiments are also
+investigated based on a Monte Carlo analysis of parameter estimation, showing
+that the circular polarization degree, varepsilon, which is the asymmetry of
+the tensor power spectra between right- and left-handed modes normalized by the
+total amplitude, can be measured down to |varepsilon| 0.35(r/0.05)^{-0.6}.",0705.3701v3
+2007-05-31,Measuring the dark matter velocity anisotropy in galaxy clusters,"The Universe contains approximately 6 times more dark matter than normal
+baryonic matter, and a directly observed fundamental difference between dark
+matter and baryons would both be significant for our understanding of dark
+matter structures and provide us with information about the basic
+characteristics of the dark matter particle. We discuss one distinctive feature
+of dark matter structures in equilibrium, namely the property that a local dark
+matter temperature may depend on direction. This is in stark contrast to
+baryonic gases. We used X-ray observations of two nearby, relaxed galaxy
+clusters, under the assumptions of hydrostatic equilibrium and identical dark
+matter and gas temperatures in the outer cluster region, to measure this dark
+matter temperature anisotropy beta_dm, with non-parametric Monte Carlo methods.
+We find that beta_dm is greater than the value predicted for baryonic gases,
+beta_gas=0, at more than 3 sigma confidence. The observed value of the
+temperature anisotropy is in fair agreement with the results of cosmological
+N-body simulations and shows that the equilibration of the dark matter
+particles is not governed by local point-like interactions in contrast to
+baryonic gases.",0705.4680v2
+2007-06-24,Nonlinear elastic stress response in granular packings,"We study the nonlinear elastic response of a two-dimensional material to a
+localized boundary force, with the particular goal of understanding the
+differences observed between isotropic granular materials and those with
+hexagonal anisotropy. Corrections to the classical Boussinesq result for the
+stresses in an infinite half-space of a linear, isotropic material are
+developed in a power series in inverse distance from the point of application
+of the force. The breakdown of continuum theory on scales of order of the grain
+size is modeled with phenomenological parameters characterizing the strengths
+of induced multipoles near the point of application of the external force. We
+find that the data of Geng et al. on isotropic and hexagonal packings of
+photoelastic grains can be fit within this framework. Fitting the hexagonal
+packings requires a choice of elastic coefficients with hexagonal anisotropy
+stronger than that of a simple ball and spring model. For both the isotropic
+and hexagonal cases, induced dipole and quadrupole terms produce propagation of
+stresses away from the vertical direction over short distances. The scale over
+which such propagation occurs is significantly enhanced by the nonlinearities
+that generate hexagonal anisotropy.",0706.3513v2
+2007-07-01,"Giant Anisotropy of Magnetoresistance and ""Spin Valve"" effect in Antiferromagnetic $Nd_{2-x}Ce_xCuO_{4}$","We have studied anisotropic magnetoresistance (MR) and magnetization with
+rotating magnetic field (B) within $CuO_2$ plane in lightly doped AF
+$Nd_{2-x}Ce_xCuO_{4}$. \emph{A giant anisotropy} in MR is observed at low
+temperature below 5 K. The c-axis resistivity can be tuned about one order of
+magnitude just by changing B direction within $CuO_2$ plane and a scaling
+behavior between out-of-plane and in-plane MR is found. A ""Spin valve"" effect
+is proposed to understand the giant anisotropy of out-of-plane MR and the
+evolution of scaling parameters with the external field. It is found that the
+field-induced spin-flop transition of Nd$^{3+}$ layer under high magnetic field
+is the key to understand the giant anisotropy. These results suggest that a
+novel entanglement between charge and spin dominates the underlying physics.",0707.0104v3
+2007-07-03,Entanglement generation resonances in XY chains,"We examine the maximum entanglement reached by an initially fully aligned
+state evolving in an XY Heisenberg spin chain placed in a uniform transverse
+magnetic field. Both the global entanglement between one qubit and the rest of
+the chain and the pairwise entanglement between adjacent qubits is analyzed. It
+is shown that in both cases the maximum is not a monotonous decreasing function
+of the aligning field, exhibiting instead a resonant behavior for low
+anisotropies, with pronounced peaks (a total of [n/2] peaks in the global
+entanglement for an $n$-spin chain), whose width is proportional to the
+anisotropy and whose height remains finite in the limit of small anisotropy. It
+is also seen that the maximum pairwise entanglement is not a smooth function of
+the field even in small finite chains, where it may exhibit narrow peaks above
+strict plateaus. Explicit analytical results for small chains, as well as
+general exact results for finite n-spin chains obtained through the
+Jordan-Wigner mapping, are discussed.",0707.0473v1
+2007-07-17,Correlated Anisotropies in the Cosmic Far-Infrared Background Detected by MIPS/Spitzer: Constraint on the Bias,"We report the detection of correlated anisotropies in the Cosmic Far-Infrared
+Background at 160 microns. We measure the power spectrum in the Spitzer/SWIRE
+Lockman Hole field. It reveals unambiguously a strong excess above cirrus and
+Poisson contributions, at spatial scales between 5 and 30 arcminutes,
+interpreted as the signature of infrared galaxy clustering. Using our model of
+infrared galaxy evolution we derive a linear bias b=1.74 \pm 0.16. It is a
+factor 2 higher than the bias measured for the local IRAS galaxies. Our model
+indicates that galaxies dominating the 160 microns correlated anisotropies are
+at z~1. This implies that infrared galaxies at high redshifts are biased
+tracers of mass, unlike in the local Universe.",0707.2443v1
+2007-07-31,Violation of the isotropic-$\ell$ approximation in overdoped La_{2-x}Sr_xCuO_4,"Magnetotransport measurements on the overdoped cuprate La_{1.7}Sr_{0.3}CuO_4
+are fitted using the Ong construction and band parameters inferred from
+angle-resolved photoemission. Within a band picture, the low temperature Hall
+data can only be fitted satisfactorily by invoking strong basal-plane
+anisotropy in the mean-free-path $\ell$. This violation of the isotropic-$\ell$
+approximation supports a picture of dominant small-angle elastic scattering in
+cuprates due to out-of-plane substitutional disorder. We show that both band
+anisotropy and anisotropy in the elastic scattering channel strongly
+renormalize the Hall coefficient in overdoped La_{2-x}Sr_xCuO_4 over a wide
+doping and temperature range.",0707.4601v1
+2007-09-07,Detecting Cosmic Strings in the CMB with the Canny Algorithm,"Line discontinuities in cosmic microwave background anisotropy maps are a
+distinctive prediction of models with cosmic strings. These signatures are
+visible in anisotropy maps with good angular resolution and should be
+identifiable using edge detection algorithms. One such algorithm is the Canny
+algorithm. We study the potential of this algorithm to pick out the line
+discontinuities generated by cosmic strings. By applying the algorithm to
+small-scale microwave anisotropy maps generated from theoretical models with
+and without cosmic strings, we find that, given an angular resolution of
+several minutes of arc, cosmic strings can be detected down to a limit of the
+mass per unit length of the string which is one order of magnitude lower than
+the current upper bounds.",0709.0982v3
+2007-09-12,The velocity distribution of SDSS satellites in MOND,"The recent SDSS measured velocity distribution of satellite galaxies has been
+modelled in the context of MOND. We show that even when the extra constraint of
+adhering to the projected satellite number density profile is added, the two
+line of sight (los) velocity dispersion profiles presented in Klypin & Prada
+(2007) can be matched simply with a radially varying anisotropy. Interestingly,
+the anisotropies required to fit the los velocity dispersions are remarkably
+similar to the anisotropies generated by dissipationless collapse simulations
+in MOND. The mass-to-light ratios of the two host galaxies used are sensible
+and positivity of the distribution function is satisfied.",0709.1966v1
+2007-09-22,Measuring Quark-Gluon-Plasma Thermalization Time with Dileptons,"We calculate the medium dilepton yield from a quark-gluon plasma which has a
+time-dependent local momentum-space anisotropy. A phenomenological model for
+the hard momentum scale, p_hard(tau), and plasma anisotropy parameter, xi(tau),
+is constructed which interpolates between free streaming behavior at early
+times (tau << tau_iso) and ideal hydrodynamic behavior at late times (tau >>
+tau_iso). We show that high-energy dilepton production is sensitive to the
+assumed plasma isotropization time, tau_iso, and can therefore be used to
+experimentally determine the time of onset for hydrodynamic expansion of a
+quark-gluon plasma and the magnitude of expected early-time momentum-space
+anisotropies.",0709.3576v3
+2007-10-05,Biconical structures in two-dimensional anisotropic Heisenberg antiferromagnets,"Square lattice Heisenberg and XY antiferromagnets with uniaxial anisotropy in
+a field along the easy axis are studied. Based on ground state considerations
+and Monte Carlo simulations, the role of biconical structures in the transition
+region between the antiferromagnetic and spin--flop phases is analyzed. In
+particular, adding a single--ion anisotropy to the XXZ antiferromagnet, one
+observes, depending on the sign of that anisotropy, either an intervening
+biconical phase or a direct transition of first order separating the two
+phases. In case of the anisotropic XY model, the degeneracy of the ground
+state, at a critical field, in antiferromagnetic, spin--flop, and bidirectional
+structures seems to result, as in the case of the XXZ model, in a narrow
+disordered phase between the antiferromagnetic and spin--flop phases, dominated
+by bidirectional fluctuations.",0710.1251v2
+2007-10-06,Global anisotropy of arrival directions of ultra-high-energy cosmic rays: capabilities of space-based detectors,"Planned space-based ultra-high-energy cosmic-ray detectors (TUS, JEM-EUSO and
+S-EUSO) are best suited for searches of global anisotropies in the distribution
+of arrival directions of cosmic-ray particles because they will be able to
+observe the full sky with a single instrument. We calculate quantitatively the
+strength of anisotropies associated with two models of the origin of the
+highest-energy particles: the extragalactic model (sources follow the
+distribution of galaxies in the Universe) and the superheavy dark-matter model
+(sources follow the distribution of dark matter in the Galactic halo). Based on
+the expected exposure of the experiments, we estimate the optimal strategy for
+efficient search of these effects.",0710.1382v2
+2007-10-18,FFLO state in thin superconducting films,"We present the analysis of the inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov
+(FFLO) superconducting state in thin superconducting films in the parallel
+magnetic field. For the tetragonal crystal symmetry (relevant to CeCoIn$_{5}$ -
+the most probable candidate for the FFLO state formation) we predict a very
+peculiar in-plane angular dependence of the FFLO critical field due to the
+orbital effect. In the uniform superconducting state the critical field should
+be isotropic. The magnetic field pins also the direction of the FFLO modulation
+permitting thus to study the critical current anisotropy. Our calculations
+reveal a strong critical current anisotropy in the FFLO state in sharp contrast
+with the usual superconducting state. The predicted characteristic anisotropies
+of the critical field and critical current may provide an unambiguous probe of
+the FFLO phase formation.",0710.3613v1
+2007-11-07,Characterization of graphene through anisotropy of constant-energy maps in angle-resolved photoemission,"We show theoretically how constant-energy maps of the angle-resolved
+photoemission intensity can be used to test wave function symmetry in graphene.
+For monolayer graphene, we demonstrate that the observed anisotropy of ARPES
+spectra is a manifestation of what has been recently branded as electronic
+chirality. For bilayer graphene, we show that the anisotropy of the
+constant-energy maps may be used to extract information about the magnitude and
+sign of interlayer coupling parameters and about symmetry breaking inflicted on
+a bilayer by the underlying substrate.",0711.1129v2
+2007-12-14,Mass modelling of galaxy clusters via velocity moments,"We summarize the method of mass modelling of galaxy clusters based on
+reproducing the dispersion and kurtosis of the projected velocity distribution
+of galaxies. The models are parametrized within the framework of the NFW
+density profile, characterized by the virial mass and concentration, together
+with the constant anisotropy of galaxy orbits. The use of velocity dispersion
+alone does not allow to constrain all the three parameters from kinematic data
+due to the mass-anisotropy degeneracy. The degeneracy is broken by introducing
+the fourth velocity moment, the kurtosis. We tested the method based on fitting
+both moments on mock data sets drawn from simulated dark matter haloes and
+showed it to reproduce reliably the properties of the haloes. The method has
+been applied to estimate the mass, concentration and anisotropy of more than 20
+clusters which allowed us to confirm, for the first time using kinematic data,
+the mass-concentration relation found in N-body simulations.",0712.2368v1
+2008-01-06,Avalanches in anisotropic sheared granular media,"We study the influence of particle shape anisotropy on the occurrence of
+avalanches in sheared granular media. We use molecular dynamic simulations to
+calculate the relative movement of two tectonic plates. % with transform
+boundaries. Our model considers irregular polygonal particles constituting the
+material within the shear zone. We find that the magnitude of the avalanches is
+approximately independent on particle shape and in good agreement with the
+Gutenberg-Richter law, but the aftershock sequences are strongly influenced by
+the particle anisotropy yielding variations on the exponent characterizing the
+empirical Omori's law. Our findings enable one to identify the presence of
+anisotropic particles at the macro-mechanical level only by observing the
+avalanche sequences of real faults. In addition, we calculate the probability
+of occurrence of an avalanche for given values of stiffness or frictional
+strength and observe also a significant influence of the particle anisotropy.",0801.0862v1
+2008-01-14,Anisotropic Susceptibility of La_2-xSr_xCoO_4 related to the Spin States of Cobalt,"We present a study of the magnetic susceptibility of La_2-xSr_xCoO_4 single
+crystals in a doping range 0.3<=x<=0.8. Our data shows a pronounced magnetic
+anisotropy for all compounds. This anisotropy is in agreement with a low-spin
+ground state (S=0) of Co^3+ for x>=0.4 and a high-spin ground state (S=3/2) of
+Co^2+. We compare our data with a crystal-field model calculation assuming
+local moments and find a good description of the magnetic behavior for x>=0.5.
+This includes the pronounced kinks observed in the inverse magnetic
+susceptibility, which result from the anisotropy and low-energy excited states
+of Co^2+ and are not related to magnetic ordering or temperature-dependent
+spin-state transitions.",0801.2087v1
+2008-01-21,Uniaxially anisotropic antiferromagnets in a field on a square lattice,"Classical uniaxially anisotropic Heisenberg and XY antiferromagnets in a
+field along the easy axis on a square lattice are analysed, applying ground
+state considerations and Monte Carlo techniques. The models are known to
+display antiferromagnetic and spin-flop phases. In the Heisenberg case, a
+single-ion anisotropy is added to the XXZ antiferromagnet, enhancing or
+competing with the uniaxial exchange anisotropy. Its effect on the stability of
+non-collinear structures of biconical type is studied. In the case of the
+anisotropic XY antiferromagnet, the transition region between the
+antiferromagnetic and spin-flop phases is found to be dominated by degenerate
+bidirectional fluctuations. The phase diagram is observed to resemble closely
+that of the XXZ antiferromagnet without single-ion anisotropy.",0801.3217v1
+2008-02-21,Discrete Fracture Model with Anisotropic Load Sharing,"A two-dimensional fracture model where the interaction among elements is
+modeled by an anisotropic stress-transfer function is presented. The influence
+of anisotropy on the macroscopic properties of the samples is clarified, by
+interpolating between several limiting cases of load sharing. Furthermore, the
+critical stress and the distribution of failure avalanches are obtained
+numerically for different values of the anisotropy parameter $\alpha$ and as a
+function of the interaction exponent $\gamma$. From numerical results, one can
+certainly conclude that the anisotropy does not change the crossover point
+$\gamma_c=2$ in 2D. Hence, in the limit of infinite system size, the crossover
+value $\gamma_c=2$ between local and global load sharing is the same as the one
+obtained in the isotropic case. In the case of finite systems, however, for
+$\gamma\le2$, the global load sharing behavior is approached very slowly.",0802.3003v1
+2008-03-10,Distribution Function of Dark Matter with Constant Anisotropy,"N-body simulations of dark matter halos show that the density is cusped near
+the center of the halo. The density profile behaves as $r^{-\gamma}$ in the
+inner parts, where $\gamma \simeq 1$ for the NFW model and $\gamma \simeq 1.5$
+for the Moore's model, but in the outer parts, both models agree with each
+other in the asymptotic behavior of the density profile. The simulations also
+show the information about anisotropy parameter $\beta(r)$ of velocity
+distribution. $\beta\approx 0$ in the inner part and $\beta\approx 0.5$
+(radially anisotropic) in the outer part of the halo. We provide some
+distribution functions $F(E,L)$ with the constant anisotropy parameter $\beta$
+for the two spherical models of dark matter halos: a new generalized NFW model
+and a generalized Moore model. There are two parameters $\alpha$ and $\epsilon$
+for those two generalized models to determine the asymptotic behavior of the
+density profile. In this paper, we concentrate on the situation of
+$\beta(r)=1/2$ from the viewpoint of the simulation.",0803.1431v2
+2008-03-23,S-Z Power Spectra,"There is some observational evidence for earlier evolution of clusters of
+galaxies than predicted in the standard LambdaCDM model with a Gaussian
+primordial density fluctuation field, and a low value for the mass variance
+parameter sigma_8. Particularly difficult in this model is the interpretation
+of possible excess CMB anisotropy on cluster scales as due to the
+Sunyaev-Zeldovich (S-Z) effect. We have calculated S-Z power spectra in the
+standard model, and in two alternative models which predict higher cluster
+abundance - a model with non-Gaussian PDF, and an early dark energy model. As
+anticipated, the levels of S-Z power in the latter two models are significantly
+higher than in the standard model, and in good agreement with current
+measurements of CMB anisotropy at high multipole values. Our results provide a
+sufficient basis for testing the viability of the three models by futur high
+quality measurements of cluster abundance and the anisotropy induced by the S-Z
+effect.",0803.3323v1
+2008-03-24,Solution of the Holstein polaron anisotropy problem,"We study Holstein polarons in three-dimensional anisotropic materials. Using
+a variational exact diagonalization technique we provide highly accurate
+results for the polaron mass and polaron radius. With these data we discuss the
+differences between polaron formation in dimension one and three, and at small
+and large phonon frequency. Varying the anisotropy we demonstrate how a polaron
+evolves from a one-dimensional to a three-dimensional quasiparticle. We thereby
+resolve the issue of polaron stability in quasi-one-dimensional substances and
+clarify to what extent such polarons can be described as one-dimensional
+objects. We finally show that even the local Holstein interaction leads to an
+enhancement of anisotropy in charge carrier motion.",0803.3425v2
+2008-04-09,Anisotropic interaction of two-level systems with acoustic waves in disordered crystals,"We apply the model introduced in Phys. Rev. B 75, 064202 (2007),
+cond-mat/0610469, to calculate the anisotropy effect in the interaction of two
+level systems with phonons in disordered crystals. We particularize our
+calculations to cubic crystals and compare them with the available experimental
+data to extract the parameters of the model. With these parameters we calculate
+the interaction of the dynamical defects in the disordered crystal with phonons
+(or sound waves) propagating along other crystalographic directions, providing
+in this way a method to investigate if the anisotropy comes from the two-level
+systems being preferably oriented in a certain direction or solely from the
+lattice anisotropy with the two-level systems being isotropically oriented.",0804.1481v1
+2008-04-24,Covalency effects on the magnetism of EuRh2P2,"In experiments, the ternary Eu pnictide EuRh2P2 shows an unusual coexistence
+of a non-integral Eu valence of about 2.2 and a rather high Neel temperature of
+50 K. In this paper, we present a model which explains the non-integral Eu
+valence via covalent bonding of the Eu 4f-orbitals to P2 molecular orbitals. In
+contrast to intermediate valence models where the hybridization with
+delocalized conduction band electrons is known to suppress magnetic ordering
+temperatures to at most a few Kelvin, covalent hybridization to the localized
+P2 orbitals avoids this suppression. Using perturbation theory we calculate the
+valence, the high temperature susceptibility, the Eu single-ion anisotropy and
+the superexchange couplings of nearest and next-nearest neighbouring Eu ions.
+The model predicts a tetragonal anisotropy of the Curie constants. We suggest
+an experimental investigation of this anisotropy using single crystals. From
+experimental values of the valence and the two Curie constants, the three free
+parameters of our model can be determined.",0804.3905v1
+2008-05-02,"Quasistatic rheology, force transmission and fabric properties of a packing of irregular polyhedral particles","By means of contact dynamics simulations, we investigate a dense packing
+composed of polyhedral particles under quasistatic shearing. The effect of
+particle shape is analyzed by comparing the polyhedra packing with a packing of
+similar characteristics except for the spherical shape of the particles. The
+polyhedra packing shows higher shear stress and dilatancy but similar
+stress-dilatancy relation compared to the sphere packing. A harmonic
+approximation of granular fabric is presented in terms of branch vectors
+(connecting particle centers) and contact force components along and
+perpendicular to the branch vectors. It is found that the origin of enhanced
+shear strength of the polyhedra packing lies in its higher force anisotropy
+with respect to the sphere packing which has a higher fabric anisotropy.
+Various contact types (face-vertex, face-face, etc) contribute differently to
+force transmission and fabric anisotropy. In particular, most face-face
+contacts belong to strong force chains along the major principal stress
+direction whereas vertex-face contacts are correlated with weak forces and
+oriented on average along the minor principal stress direction in steady
+shearing.",0805.0178v1
+2008-05-16,Characterization of Geometric Structures of Biaxial Nematic Phases,"The ordering matrix, which was originally introduced by de Gennes, is a
+well-known mathematical device for describing orientational order of biaxial
+nematic liquid crystal. In this paper we propose a new interpretation of the
+ordering matrix. We slightly modify the definition of the ordering matrix and
+call it the geometric order parameter. The geometric order parameter is a
+linear transformation which transforms a tensorial quantity of an individual
+molecule to a tensorial quantity observed at a macroscopic scale. The degree of
+order is defined as the singular value of the geometric order parameter. We
+introduce the anisotropy diagram, which is useful for classification and
+comparison of various tensorial quantities. As indices for evaluating
+anisotropies of tensorial quantities, we define the degree of anisotropy and
+the degree of biaxiality. We prove that a simple diagrammatic relation holds
+between a microscopic tensor and a macroscopic tensor. We provide a
+prescription to formulate the Landau-de Gennes free energy of a system whose
+constituent molecules have an arbitrary shape. We apply our prescription to a
+system which consists of D_{2h}-symmetric molecules.",0805.2471v2
+2008-05-23,AC and DC Conductivity Anisotropies in Lightly Doped La(2-x)Sr(x)CuO(4),"The AC and DC conductivity anisotropies in the low temperature orthorhombic
+phase of lightly doped La(2-x)Sr(x)CuO(4) are ascribed to the rotational
+symmetry broken, localized impurity states resulting from the trapping of doped
+holes by Sr ions. The two lowest-energy p-wave-like states are split by
+orthorhombicity and partially filled with holes. This leaves a unique imprint
+in AC conductivity, which shows two distinct infrared continuum absorption
+energies. Furthermore, the existence of two independent channels for hopping
+conductivity, associated to the two orthorhombic directions, explains
+quantitatively the observed low temperature anisotropies in DC conductivity.",0805.3609v2
+2008-05-26,"Magnetic reversal under external field and current-driven domain wall motion in (Ga,Mn)As: influence of extrinsic pinning","We investigate the anisotropy of magnetic reversal and current-driven domain
+wall motion in annealed Ga_0.95Mn_0.05As thin films and Hall bar devices with
+perpendicular magnetic anisotropy. Hall bars with current direction along the
+[110] and [1-10] crystallographic axes are studied. The [110] device shows
+larger coercive field than the [1-10] device. Strong anisotropy is observed
+during magnetic reversal between [110] and [1-10] directions. A power law
+dependence is found for both devices between the critical current (JC) and the
+magnetization (M), with J_C is proportional to M^2.6. The domain wall motion is
+strongly influenced by the presence of local pinning centres.",0805.3998v1
+2008-06-03,Critical Fields and Anisotropy of NdO0.82F0.18FeAs Single Crystals,"The newly discovered iron-based superconductors have stimulated enormous
+interests in the field of superconductivity. Since the new superconductor is a
+layered system, the anisotropy is a parameter with the first priority to know.
+Meanwhile any relevant message about the critical fields (upper critical field
+and irreversibility line) are essentially important. By using flux method, we
+have successfully grown the single crystals NdO0.82F0.18FeAs at ambient
+pressure. Resistive measurements reveal a surprising discovery that the
+anisotropy \Gamma = (mc/mab)^{1/2} is below 5, which is much smaller than the
+theoretically calculated results. The data measured up to 400 K show a
+continuing curved feature which prevents a conjectured linear behavior for an
+unconventional metal. The upper critical fields determined based on the
+Werthamer-Helfand-Hohenberg formula are H_{c2}^{H||ab}(T=0 K) = 304 T and
+H_{c2}^{H||c}(T=0 K)=62-70 T, indicating a very encouraging application of the
+new superconductors.",0806.0532v1
+2008-06-23,Evolution of Anisotropies in Eddington-Born-Infeld Cosmology,"Recently a Born-Infeld action for dark energy and dark matter that uses
+additional affine connections was proposed. At background level, it was shown
+that the new proposal can mimic the standard cosmological evolution. In Bianchi
+cosmologies, contrary to the scalar field approach (e.g., Chaplygin gas), the
+new approach leads to anisotropic pressure, raising the issues of stability of
+the isotropic solution under anisotropic perturbations and, being it stable,
+how the anisotropies evolve. In this work, the Eddington-Born-Infeld proposal
+is extended to a Bianchi type I scenario and residual post-inflationary
+anisotropies are shown to decay in time. Moreover, it is shown that the shears
+decay following a damped oscillatory pattern, instead of the standard
+exponential-like decay. Allowing for some fine tuning on the initial
+conditions, standard theoretical bounds on the shears can be avoided.",0806.3613v3
+2008-07-09,Delayed Recombination and Cosmic Parameters,"Current cosmological constraints from Cosmic Microwave Background (CMB)
+anisotropies are typically derived assuming a standard recombination scheme,
+however additional resonance and ionizing radiation sources can delay
+recombination, altering the cosmic ionization history and the cosmological
+inferences drawn from CMB data. We show that for recent observations of CMB
+anisotropy, from the Wilkinson Microwave Anisotropy Probe satellite mission
+5-year survey (WMAP5) and from the ACBAR experiment, additional resonance
+radiation is nearly degenerate with variations in the spectral index, n_s, and
+has a marked effect on uncertainties in constraints on the Hubble constant, age
+of the universe, curvature and the upper bound on the neutrino mass. When a
+modified recombination scheme is considered, the redshift of recombination is
+constrained to z_*=1078\pm11, with uncertainties in the measurement weaker by
+one order of magnitude than those obtained under the assumption of standard
+recombination while constraints on the shift parameter are shifted by 1-sigma
+to R=1.734\pm0.028. Although delayed recombination limits the precision of
+parameter estimation from the WMAP satellite, we demonstrate that this should
+not be the case for future, smaller angular scales measurements, such as those
+by the Planck satellite mission.",0807.1420v1
+2008-07-16,Solid behavior of anisotropic rigid frictionless bead assemblies,"We investigate the structure and mechanical behavior of assemblies of
+frictionless, nearly rigid equal-sized beads, in the quasistatic limit, by
+numerical simulation. Three different loading paths are explored: triaxial
+compression, triaxial extension and simple shear. Generalizing recent results
+[1], we show that the material, despite rather strong finite sample size
+effects, is able to sustain a finite deviator stress in the macroscopic limit,
+along all three paths, without dilatancy. The shape of the yield surface is
+adequately described by a Lade-Duncan (rather than Mohr-Coulomb) criterion.
+While scalar state variables keep the same values as in isotropic systems,
+fabric and force anisotropies are each characterized by one parameter and are
+in one-to-one correspondence with principal stress ratio along all three
+loading paths.The anisotropy of the pair correlation function extends to a
+distance between bead surfaces on the order of 10% of the diameter. The tensor
+of elastic moduli is shown to possess a nearly singular, uniaxial structure
+related to stress anisotropy. Possible stress-strain relations in monotonic
+loading paths are also discussed.",0807.2513v2
+2008-07-29,Anisotropic pairing in the iron pnictides,"We determine the anisotropy of the spin fluctuation induced pairing gap on
+the Fermi surface of the FeAs based superconductors as function of the exchange
+and Hund's coupling $J_{H}$. We find that for sufficiently large $J_{H}$,
+nearly commensurate magnetic fluctuations yield a fully gapped
+$s^{\pm}$-pairing state with small anisotropy of the gap amplitude on each
+Fermi surface sheet, but significant variations of the gap amplitude for
+different sheets of the Fermi surface. In particular, we obtain the large
+variation of the gap amplitude on different Fermi surface sheets, as seen in
+ARPES experiments. For smaller values of Hund's coupling incommensurate
+magnetic fluctuations yield an $s^{\pm}$-pairing state with line nodes. Such a
+state is also possible once the anisotropy of the material is reduced and three
+dimensional effects come into play.",0807.4566v2
+2008-08-04,Primordial non-Gaussianity estimator: the inhomogeneous noise effect,"Since the inhomogeneous instrument noise can produce extra non-Gaussianity in
+the CMB anisotropy, its effect should be carefully subtracted in the primordial
+non-Gaussianity estimation. We calculate the probability distribution function
+of the CMB anisotropy for local type of non-Gaussianity, from which the optimal
+estimator in the general case (inhomogeneous noise and cut sky) is obtained.
+The new estimator obtained here is different from the popular one, since the
+inhomogeneous noise and cut sky effects are completely accounted. The CMB
+anisotropy in the new estimator is noise weighted. The noise weight is
+different from that used by WMAP Group in their 5-year data analysis. Although
+it is still difficult to calculate the new estimator rigorously, for the case
+of the slightly inhomogeneous noise, there exists a series expansion method to
+compute the new estimator. Each order in the series is suppressed by two
+factors, $(\frac{\sigma^2}{\sigma^2_{i}}-1)$ and $\frac{C_l}{C^{tot}_{l}}$,
+which make the method feasible. Through the Edgeworth expansion we can
+generalize our discussion to other types of non-Gaussianity.",0808.0424v1
+2008-08-12,Anisotropy and Magnetism in the LSDA+U Method,"Consequences of anisotropy (variation of orbital occupation) and magnetism,
+and their coupling, are analyzed for LSDA+U functionals, both the commonly used
+ones as well as less commonly applied functionals. After reviewing and
+extending some earlier observations for an isotropic interaction, the
+anisotropies are examined more fully and related to use with the local density
+(LDA) or local spin density (LSDA) approximations. The total energies of all
+possible integer configurations of an open $f$ shell are presented for three
+functionals, where some differences are found to be dramatic. Differences in
+how the commonly used ""around mean field"" (AMF) and ""fully localized limit""
+(FLL) functionals perform are traced to such differences. The LSDA+U
+interaction term, applied self-consistently, usually enhances spin magnetic
+moments and orbital polarization, and the double-counting terms of both
+functionals provide an opposing, moderating tendency (""suppressing the magnetic
+moment""). The AMF double counting term gives magnetic states a significantly
+larger energy penalty than does the FLL counterpart.",0808.1706v3
+2008-08-14,Determination of the single-ion anisotropy energy in a S = 5/2 kagome antiferromagnet using X-ray absorption spectroscopy,"We report x-ray absorption and x-ray linear dichroism measurements at the Fe
+L2,3 edges of the geometrically frustrated systems of potassium and hydronium
+iron jarosite. Comparison with simulated spectra, involving ligand-field
+multiplet calculations modelling the 3d-2p hybridization between the iron ion
+and the oxygen ligands, has yielded accurate estimates for the ligand metal-ion
+hybridization and the resulting single-ion crystal field anisotropy energy.
+Using this method we provide an experimentally verified scenario for the
+appearance of a single-ion anisotropy in this nominally high-spin 3d5 orbital
+singlet 6S system, which accounts for features of the spin-wave dispersion in
+the long-range ordered ground state of potassium iron jarosite.",0808.1969v2
+2008-08-18,"Upper critical field, anisotropy, and superconducting properties of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ single crystals","The temperature dependent resistivity of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ (x =
+0.23, 0.25, 0.28 and 0.4) single crystals and the angle dependent resistivity
+of superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystals were
+measured in magnetic fields up to 9 T. The measurements of temperature
+dependent resistivity for samples with different doping levels revealed very
+high upper critical fields which increase with the transition temperature
+monotonously, and a very low superconducting anisotropy ratio
+$\Gamma=H_{c2}^{ab}/H_{c2}^c \approx$ 2. By scaling the resistivity in the
+frame of the anisotropic Ginzburg-Landau theory, the angle dependent
+resistivity of the Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystal measured with
+different magnetic fields at a certain temperature collapsed onto one curve. As
+the only scaling parameter, the anisotropy $\Gamma$ was determined
+alternatively for each temperature and was found to be between two and three.",0808.2392v3
+2008-08-20,The ground-state magnetic ordering of the spin-1/2 frustrated J1-J2 XXZ model on the square lattice,"Using the coupled-cluster method for infinite lattices and the exact
+diagonalization method for finite lattices, we study the influence of an
+exchange anisotropy Delta on the ground-state phase diagram of the spin-1/2
+frustrated J1-J2 XXZ antiferromagnet on the square lattice. We find that
+increasing Delta>1 (i.e. an Ising type easy-axis anisotropy) as well as
+decreasing Delta<1 (i.e. an XY type easy-plane anisotropy) both lead to a
+monotonic shrinking of the parameter region of the magnetically disordered
+quantum phase. Finally, at Delta~1.9 this quantum phase disappears, whereas in
+pure XY limit (Delta=0) there is still a narrow region around J2 =0.5J1 where
+the quantum paramagnetic ground-state phase exists.",0808.2743v2
+2008-09-14,Geometric-Phase-Effect Tunnel-Splitting Oscillations in Single-Molecule Magnets with Fourth-Order Anisotropy Induced by Orthorhombic Distortion,"We analyze the interference between tunneling paths that occurs for a spin
+system with both fourth-order and second-order transverse anisotropy. Using an
+instanton approach, we find that as the strength of the second-order transverse
+anisotropy is increased, the tunnel splitting is modulated, with zeros
+occurring periodically. This effect results from the interference of four
+tunneling paths connecting easy-axis spin orientations and occurs in the
+absence of any magnetic field.",0809.2289v2
+2008-09-15,Thermodynamic Properties of Kagome Antiferromagnets with different Perturbations,"We discuss the results of several small perturbations to the thermodynamic
+properties of Kagome Lattice Heisenberg Model (KLHM) at high and intermediate
+temperatures, including Curie impurities, dilution, in-plane and out of plane
+Dzyaloshinski-Moria (DM) anisotropies and exchange anisotropy. We examine the
+combined role of Curie impurities and dilution in the behavior of uniform
+susceptibility. We also study the changes in specific heat and entropy with
+various anisotropies. Their relevance to newly discovered materials
+ZnCu3(OH)6Cl2 is explored. We find that the magnetic susceptibility is well
+described by about 6 percent impurity and dilution. We also find that the
+entropy difference between the material and KLHM is well described by the DM
+parameter D_z/J~0.1.",0809.2621v2
+2008-10-20,Measurement of the dark matter velocity anisotropy profile in galaxy clusters,"Dark matter particles form halos that contribute the major part of the mass
+of galaxy clusters. The formation of these cosmological structures have been
+investigated both observationally and in numerical simulations, which have
+confirmed the existence of a universal mass profile. However, the dynamic
+behaviour of dark matter in halos is not as well understood. We have used
+observations of 16 equilibrated galaxy clusters to show that the random
+velocities of dark matter particles are larger on average along the radial
+direction than along the tangential, and that the magnitude of this velocity
+anisotropy is radially varying. Our measurement implies that the collective
+behaviour of dark matter particles is fundamentally different from that of
+normal particles and the radial variation of the anisotropy velocity agrees
+with the predictions of numerical simulation.",0810.3676v1
+2008-10-30,Patch coalescence as a mechanism for eukaryotic directional sensing,"Eukaryotic cells possess a sensible chemical compass allowing them to orient
+toward sources of soluble chemicals. The extracellular chemical signal triggers
+separation of the cell membrane into two domains populated by different
+phospholipid molecules and oriented along the signal anisotropy. We propose a
+theory of this polarization process, which is articulated into subsequent
+stages of germ nucleation, patch coarsening and merging into a single domain.
+We find that the polarization time, $t_\epsilon$, depends on the anisotropy
+degree $\epsilon$ through the power law $t_\epsilon\propto \epsilon^{-2}$, and
+that in a cell of radius $R$ there should exist a threshold value
+$\epsilon_\mathrm{th}\propto R^{-1}$ for the smallest detectable anisotropy.",0810.5409v1
+2008-11-04,The Anisotropic Spatial Distribution of Hypervelocity Stars,"We study the distribution of angular positions and angular separations of
+unbound hypervelocity stars (HVSs). HVSs are spatially anisotropic at the
+3-sigma level. The spatial anisotropy is significant in Galactic longitude, not
+in latitude, and the inclusion of lower velocity, possibly bound HVSs reduces
+the significance of the anisotropy. We discuss how the observed distribution of
+HVSs may be linked to their origin. In the future, measuring the distribution
+of HVSs in the southern sky will provide additional constraints on the spatial
+anisotropy and the origin of HVSs.",0811.0612v2
+2008-11-11,Signals of Statistical Anisotropy in WMAP Foreground-Cleaned Maps,"Recently a symmetry-based method to test for statistical isotropy of the
+cosmic microwave background was developed. We apply the method to
+template-cleaned 3-year and 5-year WMAP-$DA$ maps. We examine a wide range of
+angular multipoles from $2 < l < 300$. The analysis detects statistically
+signicant signals of anisotropy inconsistent with an isotropic CMB in some of
+the foreground cleaned maps. We are unable to resolve whether the anomalies
+have a cosmological, local astrophysical or instrumental origin. Assuming the
+anisotropy arises due to residual foreground contamination, we estimate the
+residual foreground power in the maps. For the W band maps, we also find a
+highly improbable degree of isotropy we cannot explain. We speculate that
+excess isotropy may be caused by faulty modeling of detector noise.",0811.1639v2
+2008-11-13,The flattening and the orbital structure of early-type galaxies and collisionless N-body binary disk mergers,"We use oblate axisymmetric dynamical models including dark halos to determine
+the orbital structure of intermediate mass to massive Coma early-type galaxies.
+We find a large variety of orbital compositions. Averaged over all sample
+galaxies the unordered stellar kinetic energy in the azimuthal and the radial
+direction are of the same order, but they can differ by up to 40 percent in
+individual systems. In contrast, both for rotating and non-rotating galaxies
+the vertical kinetic energy is on average smaller than in the other two
+directions. This implies that even most of the rotating ellipticals are
+flattened by an anisotropy in the stellar velocity dispersions. Using
+three-integral axisymmetric toy models we show that flattening by stellar
+anisotropy maximises the entropy for a given density distribution.
+Collisionless disk merger remnants are radially anisotropic. The apparent lack
+of strong radial anisotropy in observed early-type galaxies implies that they
+may not have formed from mergers of disks unless the influence of dissipational
+processes was significant.",0811.2130v1
+2008-12-03,Quantum communication through anisotropic Heisenberg XY spin chains,"We study quantum communication through an anisotropic Heisenberg XY chain in
+a transverse magnetic field. We find that for some time $t$ and anisotropy
+parameter $\gamma$, one can transfer a state with a relatively high fidelity.
+In the strong-field regime, the anisotropy does not significantly affect the
+fidelity while in the weak-field regime the affect is quite pronounced. The
+most interesting case is the the intermediate regime where the oscillation of
+the fidelity with time is low and the high-fidelity peaks are relatively broad.
+This would, in principle, allow for quantum communication in realistic
+circumstances. Moreover, we calculate the purity, or tangle, as a measure of
+the entanglement between one spin and all the other spins in the chain and find
+that the stronger the anisotropy and exchange interaction, the more
+entanglement will be generated for a given time.",0812.0645v2
+2008-12-08,CMB anisotropy induced by tachyonic perturbations of dark energy,"We study effects of possible tachyonic perturbations of dark energy on the
+CMB temperature anisotropy. Motivated by some models of phantom energy, we
+consider both Lorentz-invariant and Lorentz-violating dispersion relations for
+tachyonic perturbations. We show that in the Lorentz-violating case, the shape
+of the CMB anisotropy spectrum generated by the tachyonic perturbations is very
+different from that due to adiabatic scalar perturbations and, if sizeable, it
+would be straightforwardly distinguished from the latter. The tachyonic
+contribution improves slightly the agreement between the theory and data;
+however, this improvement is not statistically significant, so our analysis
+results in limits on the time scale of the tachyonic instability. In the
+Lorentz-invariant case, tachyonic contribution is a rapidly decaying function
+of the multipole number $l$, so that the entire observed dipole can be
+generated without conflicting the data at higher multipoles. On the
+conservative side, our comparison with the data places limit on the absolute
+value of the (imaginary) tachyon mass in the Lorentz-invariant case.",0812.1459v2
+2008-12-15,Scattering polarization due to light source anisotropy,"We consider the polarization arising from scattering in an envelope
+illuminated by a central anisotropic source. Spherical harmonics are used to
+describe both the light source anisotropy and the envelope density distribution
+functions of the scattering particles. This framework demonstrates how the net
+resultant polarization arises from a superposition of three basic ""shape""
+functions: the distribution of source illumination, the distribution of
+envelope scatterers, and the phase function for dipole scattering. Specific
+expressions for the Stokes parameters and scattered flux are derived for the
+case of an ellipsoidal light source inside an ellipsoidal envelope, with
+principal axes that are generally not aligned. Two illustrative examples are
+considered: (a) axisymmetric mass loss from a rapidly rotating star, such as
+may apply to some Luminous Blue Variables, and (b) a Roche-lobe filling star in
+a binary system with a circumstellar envelope. As a general conclusion, the
+combination of source anisotropy with distorted scattering envelopes leads to
+more complex polarimetric behavior such that the source characteristics should
+be carefully considered when interpreting polarimetric data.",0812.2772v1
+2009-01-18,Stable topological textures in a classical 2D Heisenberg model,"We show that stable localized topological soliton textures (skyrmions) with
+$\pi_2$ topological charge $\nu \geq 1$ exist in a classical 2D Heisenberg
+model of a ferromagnet with uniaxial anisotropy. For this model the soliton
+exist only if the number of bound magnons exceeds some threshold value $N_{\rm
+cr}$ depending on $\nu $ and the effective anisotropy constant $K_{\rm eff}$.
+We define soliton phase diagram as the dependence of threshold energies and
+bound magnons number on anisotropy constant. The phase boundary lines are
+monotonous for both $\nu=1$ and $\nu >2$, while the solitons with $\nu=2$
+reveal peculiar nonmonotonous behavior, determining the transition regime from
+low to high topological charges. In particular, the soliton energy per
+topological charge (topological energy density) achieves a minimum neither for
+$\nu=1$ nor high charges, but rather for intermediate values $\nu=2$ or
+$\nu=3$.",0901.2707v1
+2009-01-20,"Phase diagram of the frustrated, spatially anisotropic S=1 antiferromagnet on a square lattice","We study the S=1 square lattice Heisenberg antiferromagnet with spatially
+anisotropic nearest neighbor couplings $J_{1x}$, $J_{1y}$ frustrated by a
+next-nearest neighbor coupling $J_{2}$ numerically using the density-matrix
+renormalization group (DMRG) method and analytically employing the
+Schwinger-Boson mean-field theory (SBMFT). Up to relatively strong values of
+the anisotropy, within both methods we find quantum fluctuations to stabilize
+the N\'{e}el ordered state above the classically stable region. Whereas SBMFT
+suggests a fluctuation-induced first order transition between the N\'{e}el
+state and a stripe antiferromagnet for $1/3\leq J_{1x}/J_{1y}\leq 1$ and an
+intermediate paramagnetic region opening only for very strong anisotropy, the
+DMRG results clearly demonstrate that the two magnetically ordered phases are
+separated by a quantum disordered region for all values of the anisotropy with
+the remarkable implication that the quantum paramagnetic phase of the spatially
+isotropic $J_{1}$-$J_{2}$ model is continuously connected to the limit of
+decoupled Haldane spin chains. Our findings indicate that for S=1 quantum
+fluctuations in strongly frustrated antiferromagnets are crucial and not
+correctly treated on the semiclassical level.",0901.3141v1
+2009-01-31,Anisotropy Studies with the Pierre Auger Observatory,"An anisotropy signal for the arrival directions of ultra-high energy cosmic
+rays (UHECR) of more than 99% confidence level was established using data
+collected by the Pierre Auger Observatory. Cosmic rays with energy above $\sim
+6 \times 10^{19}$ eV show a correlation with the positions of extragalactic
+nearby active galactic nuclei (AGN), being maximum for sources at less than
+$\sim$100 Mpc and angular separation of a few degrees. The evolution of the
+correlation signal with the energy shows that the departure from anisotropy
+coincides with the flux suppression observed in the spectrum, being therefore
+consistent with the hypothesis that the correlated events have their origin in
+extragalactic sources close enough to avoid significant interaction with the
+cosmic microwave background (the Greisen-Zatsepin-Kuz'min effect). Even though
+the observed signal cannot unambiguously identify AGNs as the production sites
+of UHECRs, the potential sources have to be distributed in a similar way. A
+number of additional statistical tests were performed in order to further
+understand the nature of the correlation signal.",0902.0040v1
+2009-03-03,Dzyaloshinskii-Moriya Interaction and Anisotropy effects on the Entanglement of Heisenberg Model,"In this paper the the effect of Dzyaloshinskii-Moriya interaction and
+anisotropy on the Entanglement of Heisenberg chain has been studied. While the
+anisotropy suppress the entanglement due to favoring of the alignment of spins,
+the DM interaction restores the spoiled entanglement via creation of the
+quantum fluctuations. Thermodynamic limit of the model and emerging of
+non-analytic behavior of the entanglement have also been probed. The
+singularities of the entanglement correspond to the critical boundary
+separating different phases of the model. The singularity of the entanglement
+derivative approaches the critical point from the gapped phase and will be
+symmetric if both phase on the boundary are gapped.",0903.0630v2
+2009-04-03,Simulations of Electron Magnetohydrodynamic Turbulence,"We present numerical simulations of electron magnetohydrodynamic (EMHD) and
+electron reduced MHD (ERMHD) turbulence. Comparing scaling relations, we find
+that both EMHD and ERMHD turbulence show similar spectra and anisotropy. We
+develop new techniques to study anisotropy of EMHD turbulence. Our detailed
+study of anisotropy of EMHD turbulence supports our earlier result of k_par ~
+k_perp^(1/3) scaling. We find that the high-order statistics show a scaling
+that is similar to the She-Leveque scaling. We observe that the bispectra,
+which characterize the interaction of different scales within the turbulence
+cascade, are very different for EMHD and MHD turbulence. We show that both
+decaying and driven EMHD turbulence have the same statistical properties. We
+calculate the probability distribution functions (PDFs) of MHD and EMHD
+turbulence and compare them with those of interplanetary turbulence. We find
+that, as in the case of the solar wind, the PDFs of the increments of magnetic
+field strength in MHD and EMHD turbulence are well described by the Tsallis
+distribution. We discuss implications of our results for astrophysical
+situations, including the ADAFs and magnetic reconnection.",0904.0661v2
+2009-04-12,Erratum: Statistical anisotropy in the inflationary universe,"An error was made when calculating the amplitude of the perturbed scalar mode
+after Hubble-radius crossing. When corrected, it eliminates the leading term in
+the statistical anisotropy of the power spectrum, reducing it from the
+previously claimed upper estimate of $\lesssim 10^{-2}$ to the level of at most
+$10^{-6}$, which is beyond the possibility of detection. The general conclusion
+is that a single-field inflationary scenario cannot produce statistical
+anisotropy of appreciable magnitude.",0904.1887v4
+2009-04-18,High-energy dileptons from an anisotropic quark-gluon plasma,"We calculate leading-order dilepton yields from a quark-gluon plasma which
+has a time-dependent anisotropy in momentum space. Such anisotropies can arise
+during the earliest stages of quark-gluon plasma evolution due to the rapid
+longitudinal expansion of the created matter. A phenomenological model for the
+proper time dependence of the parton hard momentum scale, p_hard, and the
+plasma anisotropy parameter, xi, is proposed. The model describes the
+transition of the plasma from a 0+1 dimensional collisionally-broadened
+expansion at early times to a 0+1 dimensional ideal hydrodynamic expansion at
+late times. We find that high-energy dilepton production is enhanced by
+pre-equilibrium emission up to 50% at LHC energies, if one assumes an
+isotropization/thermalization time of 2 fm/c. Given sufficiently precise
+experimental data this enhancement could be used to determine the plasma
+isotropization time experimentally.",0904.2866v2
+2009-04-27,Role of Oxygen Electrons in the Metal-Insulator Transition in the Magnetoresistive Oxide La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ Probed by Compton Scattering,"We have studied the [100]-[110] anisotropy of the Compton profile in the
+bilayer manganite. Quantitative agreement is found between theory and
+experiment with respect to the anisotropy in the two metallic phases (i.e. the
+low temperature ferromagnetic and the colossal magnetoresistant phase under a
+magnetic field of 7 T). Robust signatures of the metal-insulator transition are
+identified in the momentum density for the paramagnetic phase above the Curie
+temperature. We interpret our results as providing direct evidence for the
+transition from the metallic-like to the admixed ionic-covalent bonding
+accompanying the magnetic transition. The number of electrons involved in this
+phase transition is estimated from the area enclosed by the Compton profile
+anisotropy differences. Our study demonstrates the sensitivity of the Compton
+scattering technique for identifying the number and type of electrons involved
+in the metal-insulator transition.",0904.4255v1
+2009-05-08,A cluster model with random anisotropy for hysteresis jumps in CeNi$_{1-x}$Cu$_{x}$ alloys,"Some Cerium compounds exhibit hysteresis cycles with sharp macroscopic jumps
+in the magnetization at very low temperatures. This effect is attributed to the
+formation of clusters in which the anisotropy competes with the applied
+magnetic field. Here, we present a simple model where a lattice of
+ferromagnetically coupled spins is separated in clusters of random sizes and
+with random anisotropy. Within this model, we obtain hysteresis cycles
+presenting jumps that behave in a similar way that the experimental ones, and
+that disappear when increasing the temperature. The results are in good
+agreement with the hysteresis cycles measured at very low temperatures in
+CeNi$_{1-x}$Cu$_{x}$ and the comparison with these experimental results allows
+to discriminate the relative importance of the mechanisms driving the thermal
+evolution of the cycles.",0905.1219v1
+2009-05-10,Achieving Invisibility of Homogeneous Radially Anisotropic Cylinders by Effective Medium Theory,"In this paper, we establish the full-wave electromagnetic scattering theory
+to study the electromagnetic scattering from infinitely long cylinders with
+radially anisotropic coatings. We show that the total effective scattering
+width can be dramatically reduced by the suitable adjustment of the dielectric
+anisotropy of the shell, while it is not the case for tuning the dielectric
+anisotropy of the core. Furthermore, we could make the cylindrical objects
+invisible when both dielectric and magnetic anisotropies are adjusted. In the
+long wavelength limit, we develop effective medium theory to derive the
+effective isotropic permittivity and permeability for the anisotropic coated
+cylinders, and the invisibility radius ratio derived from the full-wave theory
+for small coated cylinders can be well described within the effective medium
+theory.",0905.1503v2
+2009-05-29,A general framework for multiple scattering of polarized waves including anisotropies and Berry phase,"We develop a framework for the multiple scattering of a polarized wave. We
+consider particles with spin propagating in a medium filled with scatterers. We
+write the amplitudes of each spin eigenstate in a local, mobile frame. One of
+the axes is in the direction of propagation of the particle. We use this
+representation to define a directional Green's operator of the homogeneous
+medium and also to write the spin-dependent scattering amplitudes. We show that
+this representation reveals a Berry phase. We establish a generalized
+Green-Dyson equation for the multiple scattering problem in this framework. We
+show that the generalized Green-Dyson equation can be solved by linear algebra
+if one uses a representation of the rotations based on Wigner D-matrices. The
+properties of light scattering are retrieved if we use spin 1 particles. Our
+theory allows to take into account several kinds of anisotropies like circular
+or linear dichroism and birefringence, Faraday effects andMie scattering within
+the same formalism. Several anisotropies can be present at the same time.",0905.4915v2
+2009-07-15,The use of Lorentz microscopy for the determination of magnetic reversal mechanism of exchange-biased Co30Fe70/NiMn bilayer,"Lorentz transmission electron microscopy (LTEM) combined with in-situ
+magnetizing experiments is a powerful tool for the investigation of the
+magnetization of the reversal process at the micron scale. We have implemented
+this tool on a conventional transmission electron microscope (TEM) to study the
+exchange anisotropy of a polycrystalline Co35Fe65/NiMn bilayer.
+Semi-quantitative maps of the magnetic induction were obtained at different
+field values by the differential phase contrast (DPC) technique adapted for a
+TEM (SIDPC). The hysteresis loop of the bilayer has been calculated from the
+relative intensity of magnetic maps. The curve shows the appearance of an
+exchange-bias field reveals with two distinct reversal modes of the
+magnetization: the first path corresponds to a reversal by wall propagation
+when the applied field is parallel to the anisotropy direction whereas the
+second is a reversal by coherent rotation of magnetic moments when the field is
+applied antiparallel to unidirectional anisotropy direction.",0907.2537v1
+2009-07-21,Rapidity distribution of photons from an anisotropic Quark-Gluon-Plasma,"We calculate rapidity distribution of photons due to Compton and annihilation
+processes from {\em Quark Gluon Plasma} (QGP) with pre-equilibrium
+momentum-space anisotropy. We also include contributions from hadronic matter
+with late stage transverse expansion. A phenomenological model has been used
+for the time evolution of hard momentum scale $p_{\rm hard}(\tau)$ and
+anisotropy parameter $\xi(\tau)$. As a result of pre-equilibrium momentum-space
+anisotropy, we find significant modification of photons rapidity distribution.
+For example, with {\em fixed initial condition} (FIC) {\em free-streaming}
+($\delta=2$) interpolating model we observe significant enhancement of photon
+rapidity distribution at fixed $p_T$, where as for FIC {\em
+collisionally-broadened} ($\delta=2/3$) interpolating model the yield increases
+till $y \sim 1$. Beyond that suppression is observed. With {\em fixed final
+multiplicity} (FFM) {\em free-streaming} interpolating model we predict
+enhancement of photon yield which is less than the case of FIC. Suppression is
+always observed for FFM {\em collisionally-broadened} interpolating model.",0907.3607v2
+2009-07-30,Heisenberg Spin Glass Experiments and the Chiral Ordering Scenario,"An overview is given of experimental data on Heisenberg Spin Glass materials
+so as to make detailed comparisons with numerical results on model Heisenberg
+spin glasses, with particular reference to the chiral driven ordering
+transition scenario due to Kawamura and collaborators. On weak anisotropy
+systems, experiments show critical exponents which are very similar to those
+estimated numerically for the model Heisenberg chiral ordering transition but
+which are quite different from those at Ising spin glass transitions. Again on
+weak anisotropy Heisenberg spin glasses, experimental torque data show well
+defined in-field transverse ordering transitions up to strong applied fields,
+in contrast to Ising spin glasses where fields destroy ordering. When samples
+with stronger anisotropies are studied, critical and in-field behavior tend
+progressively towards the Ising limit. It can be concluded that the essential
+physics of laboratory Heisenberg spin glasses mirrors that of model Heisenberg
+spin glasses, where chiral ordering has been demonstrated numerically.",0907.5333v1
+2009-08-01,"Phosphorous alloying: controlling the magnetic anisotropy in ferromagnetic (Ga,Mn)(As,P) Layers","Phosphorous alloying of GaMnAs thin films has been used for the manipulation
+of the magnetic anisotropies in ferromagnetic Ga0.93Mn0.07As1-yPy layers. We
+have determined the anisotropy constants as a function of temperature for
+phosphorous alloying levels between 0 and 8.8 at % for a Mn doping level of ~
+7at%. We show that it is possible to obtain layers with robust ferromagnetism
+and either in-plane or out-of plane easy axes with small barriers for
+magnetization reorientation by phosphorous alloying with y< 6at% or y> 6at%.
+The critical temperatures are not significantly increased by the P alloying.",0908.0063v2
+2009-08-04,Crystallographically oriented Co and Ni nanocrystals inside ZnO formed by ion implantation and postannealing,"In the last decade, transition-metal-doped ZnO has been intensively
+investigated as a route to room-temperature diluted magnetic semiconductors
+(DMSs). However, the origin for the reported ferromagnetism in ZnO-based DMS
+remains questionable. Possible options are diluted magnetic semiconductors,
+spinodal decomposition, or secondary phases. In order to clarify this question,
+we have performed a thorough characterization of the structural and magnetic
+properties of Co- and Ni-implanted ZnO single crystals. Our measurements reveal
+that Co or Ni nanocrystals (NCs) are the major contribution of the measured
+ferromagnetism. Already in the as-implanted samples, Co or Ni NCs have formed
+and they exhibit superparamagnetic properties. The Co or Ni NCs are
+crystallographically oriented with respect to the ZnO matrix. Their magnetic
+properties, e.g., the anisotropy and the superparamagnetic blocking
+temperature, can be tuned by annealing. We discuss the magnetic anisotropy of
+Ni NCs embedded in ZnO concerning the strain anisotropy.",0908.0458v1
+2009-08-27,"A low field technique for measuring magnetic and magneto-resistance anisotropy coefficients applied to (Ga,Mn)As","We demonstrate a simple, low cost, magneto-transport method for rapidly
+characterizing the magnetic anisotropy and anisotropic magneto-resistance (AMR)
+of ferromagnetic devices with uniaxial magnetic anisotropy. This transport
+technique is the analogue of magnetic susceptibility measurements of bulk
+material but is applicable to very small samples with low total moment. The
+technique is used to characterize devices fabricated from the dilute magnetic
+semiconductor (Ga,Mn)As. The technique allows us to probe the behavior of the
+parameters close to the Curie temperature, in the limit of the applied magnetic
+field tending to zero. This avoids the complications arising from the presence
+of paramagnetism.",0908.3960v1
+2009-09-03,Late time CMB anisotropies constrain mini-charged particles,"Observations of the temperature anisotropies induced as light from the CMB
+passes through large scale structures in the late universe are a sensitive
+probe of the interactions of photons in such environments. In extensions of the
+Standard Model which give rise to mini-charged particles, photons propagating
+through transverse magnetic fields can be lost to pair production of such
+particles. Such a decrement in the photon flux would occur as photons from the
+CMB traverse the magnetic fields of galaxy clusters. Therefore late time CMB
+anisotropies can be used to constrain the properties of mini-charged particles.
+We outline how this test is constructed, and present new constraints on
+mini-charged particles from observations of the Sunyaev-Zel'dovich effect in
+the Coma cluster.",0909.0649v1
+2009-09-16,Note on galaxy catalogues in UHECR flux modelling,"We consider the dependence of ultra-high energy cosmic ray (UHECR) flux
+predictions on the choice of galaxy catalogue. We demonstrate that model
+predictions by Koers & Tinyakov (2009b), based on the so-called KKKST
+catalogue, are in good agreement with predictions based on the XSCz catalogue,
+a recently compiled catalogue that contains spectroscopic redshifts for a large
+fraction of galaxies. This agreement refutes the claim by Kashti (2009) that
+the KKKST catalogue is not suited for studies of UHECR anisotropy due to its
+dependence on photometric redshift estimates. In order to quantify the effect
+of galaxy catalogues on flux predictions, we develop a measure of anisotropies
+associated with model flux maps. This measure offers a general criterion to
+study the effect of model parameters and assumptions on the predicted strength
+of UHECR anisotropies.",0909.3010v1
+2009-09-29,Effect of a staggered spin-orbit coupling on the occurrence of a nematic phase in Sr$_3$Ru$_2$O$_7$,"Ultra-clean crystals of Sr$_3$Ru$_2$O$_7$ undergo a metamagnetic transition
+at low temperatures. This transition shows a strong anisotropy in the applied
+field direction with the critical field $H_c$ ranging from $\sim 5.1$T for
+$H\perp c$ to $\sim 8$T for $H\parallel c$. In addition, studies on ultra-pure
+samples revealed a bifurcation of the metamagnetic line for fields in
+$c$-direction and it is argued that a nematic phase emerges between the
+magnetization jumps. The aim of this study is to explain the field-direction
+anisotropy of these phenomena. Based on a microscopic tight-binding model, we
+introduce the metamagnetic transition by means of a van Hove singularity
+scenario. We show that the rotation of the O-octahedra around the c-axis
+expected for this material introduces a staggered spin-orbit coupling within
+the planes and naturally leads to an anisotropy of the magnetic response. We
+describe the low-temperature phase as a nematic state favored by forward
+scattering processes. The spin-orbit coupling shows an influence on both, the
+critical field $H_c$ and the occurrence of the nematic phase.",0909.5392v2
+2009-10-01,First-Principles Study for the Anisotropy of Iron-based Superconductors toward Power and Device Applications,"Performing the first-principles calculations, we investigate the anisotropy
+in the superconducting state of iron-based superconductors to gain an insight
+into their potential applications. The anisotropy ratio $\gamma_\lambda$ of the
+c-axis penetration depth to the ab-plane one is relatively small in BaFe2As2
+and LiFeAs, i.e., $\gamma_\lambda \sim 3$, indicating that the transport
+applications are promising in these superconductors. On the other hand, in
+those having perovskite type blocking layers such as Sr2ScFePO3 we find a very
+large value, $\gamma_\lambda \sim 200$, comparable to that in strongly
+anisotropic high-Tc cuprate Bi2Sr2CaCu2O{8-\delta}. Thus, the intrinsic
+Josephson junction stacks are expected to be formed along the c-axis, and novel
+Josephson effects due to the multi-gap nature are also suggested in these
+superconductors.",0910.0107v1
+2009-10-09,Spin-waves in the $J_{1a}-J_{1b}-J_{2}$ orthorombic square-lattice Heisenberg models: Application to the iron pnictide materials,"Motivated by the observation of spatially anisotropic exchange constants in
+the iron pnictide materials, we study the spin-wave spectra of the
+$J_{1a}-J_{1b}-J_{2}$ Heisenberg models on a square-lattice with nearest
+neighbor exchange $J_{1a}$ along x and $J_{1b}$ along y axis and a second
+neighbor exchange $J_2$. We focus on the regime, where the spins order at
+($\pi,0$), and compute the spectra by systematic expansions around the Ising
+limit. We study both spin-half and spin-one Heisenberg models as well as a
+range of parameters to cover various cases proposed for the iron pnictide
+materials. The low-energy spectra have anisotropic spin-wave velocities and are
+renormalized with respect to linear spin-wave theory by up to 20 percent,
+depending on parameters. Extreme anisotropy, consisting of a ferromagnetic
+$J_{1b}=- |J_F|$, is best distinguished from a weak anisotropy ($J_{1a}\approx
+J_{1b}=J_1$, $J_2>J_1/2$) by the nature of the spin-waves near the wavevectors
+($0,\pi$) or ($\pi,\pi$). The reported spectra for the pnictide material
+CaFe$_2$As$_2$ clearly imply such an extreme anisotropy.",0910.1793v1
+2009-10-28,Rapidly Rotating Fermions in an Anisotropic Trap,"We consider a cold gas of non-interacting fermions in a two dimensional
+harmonic trap with two different trapping frequencies $\omega_x \leq \omega_y$,
+and discuss the effect of rotation on the density profile. Depending on the
+rotation frequency $\Omega$ and the trap anisotropy $\omega_y/\omega_x$, the
+density profile assumes two qualitatively different shapes. For small
+anisotropy ($\omega_y/\omega_x \ll \sqrt{1+4 \Omega^2/\omega_x^2}$), the
+density consists of elliptical plateaus of constant density, corresponding to
+Landau levels and is well described by a two dimensional local density
+approximation. For large anisotropy ($\omega_y/\omega_x \gg \sqrt{1+4
+\Omega^2/\omega_x^2}$), the density profile is Gaussian in the strong confining
+direction and semicircular with prominent Friedel oscillations in the weak
+direction. In this regime, a one dimensional local density approximation is
+well suited to describe the system. The crossover between the two regimes is
+smooth where the step structure between the Landau level edges turn into
+Friedel oscillations. Increasing the temperature causes the step structure or
+the Friedel oscillations to wash out leaving a Boltzmann gas density profile.",0910.5361v1
+2009-11-06,Solar cycle dependence of the diurnal anisotropy of 0.6 TeV cosmic ray intensity observed with the Matsushiro underground muon detector,"We analyze the temporal variation of the diurnal anisotropy of sub-TeV cosmic
+ray intensity observed with the Matsushiro (Japan) underground muon detector
+over two full solar activity cycles in 1985-2008. The average sidereal
+amplitude over the entire period is 0.034+-0.003 %, which is roughly one third
+of the amplitude reported from AS and deep-underground muon experiments
+monitoring multi-TeV GCR intensity suggesting a significant attenuation of the
+anisotropy due to the solar modulation. We find, on the other hand, only weak
+correlations either with the solar activity- or magnetic-cycles. We examine the
+temporal variation of the ""single-band valley depth"" (SBVD) quoted by the
+Milagro experiment and, by contrast with recent Milagro reports, we find no
+steady increase in the Matsushiro observations in a 7-year period between 2000
+and 2007. We suggest, therefore, that the steady increase of the SBVD reported
+by the Milagro experiment is not caused by the decreasing solar modulation in
+the declining phase of the 23rd solar activity cycle.",0911.1165v2
+2009-11-19,In-plane electronic anisotropy in underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ revealed by detwinning in a magnetic field,"We present results of angle-dependent magnetoresistance measurements and
+direct optical images of underdoped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ which reveal
+partial detwinning by action of a 14T magnetic field. Driven by a substantial
+magneto-elastic coupling, this result provides evidence for an electronic
+origin of the lattice distortion in underdoped iron pnictides. The observed
+anisotropy in these partially detwinned samples implies a substantial in-plane
+electronic anisotropy in the broken symmetry state, with a smaller resistivity
+along the antiferromagnetic ordering direction.",0911.3878v1
+2009-12-02,Constraints on the anisotropy of dark energy,"If the equation of state of dark energy is anisotropic there will be
+additional quadrupole anisotropy in the cosmic microwave background induced by
+the time dependent anisotropic stress quantified in terms of $\Delta w$.
+Assuming that the entire amplitude of the observed quadrupole is due to this
+anisotropy, we conservatively impose a limit of $|\Delta w| < 2.1\times
+10^{-4}$ for any value of $w\ge -1$ assuming that $\Omega_{\rm m}<0.5$. This is
+considerably tighter than that which comes from SNe. Stronger limits, upto a
+factor of 10, are possible for specific values of $\Omega_{\rm m}$ and $w$.
+Since we assume this component is uncorrelated with the stochastic component
+from inflation, we find that both the expectation value and the sample variance
+are increased. There no improvement in the likelihood of an anomalously low
+quadrupole as suggested by previous work on an elliptical universe.",0912.0397v1
+2009-12-10,Modelling the WMAP large-angle anomalies as an effect of a local density inhomogeneity,"We investigate large-angle scale temperature anisotropy in the Cosmic
+Microwave Background (CMB) with the Wilkinson Microwave Anisotropy Probe (WMAP)
+data and model the large-angle anomalies as the effect of the CMB quadrupole
+anisotropies caused by the local density inhomogeneities. The quadrupole caused
+by the local density inhomogeneities is different from the special relativity
+kinematic quadrupole. If the observer inhabits a strong inhomogeneous region,
+the local quadrupole should not be neglected. We calculate such local
+quadrupole under the assumption that there is a huge density fluctuation field
+in direction $(284^{\circ},74^{\circ})$, where the density fluctuation is
+$10^{-3}$, and its center is $\sim 112h^{-1} \rm {Mpc}$ away from us. After
+removing such mock signals from WMAP data, the power in quadrupole, $C_2$,
+increases from the range $(200\sim260\mu \rm{K^2})$ to $\sim1000\mu \rm{K^2}$.
+The quantity S, which is used to estimate the alignment between the quadrupole
+and the octopole, decreases from $(0.7\sim0.74)$ to $(0.31\sim0.37)$, while the
+model predict that $C_2=1071.5\mu \rm{K^2}$, $S=0.412$. So our local density
+inhomogeneity model can, in part, explain the WMAP low-$\ell$ anomalies.",0912.1913v1
+2010-01-14,Primordial Power Spectra from Anisotropic Inflation,"We examine cosmological perturbations in a dynamical theory of inflation in
+which an Abelian gauge field couples directly to the inflaton, breaking
+conformal invariance. When the coupling between the gauge field and the
+inflaton takes a specific form, inflation becomes anisotropic and anisotropy
+can persist throughout inflation, avoiding Wald's no-hair theorem. After
+discussing scenarios in which anisotropy can persist during inflation, we
+calculate the dominant effects of a small persistent anisotropy on the
+primordial gravitational wave and curvature perturbation power spectra using
+the ""in-in"" formalism of perturbation theory. We find that the primordial power
+spectra of cosmological perturbations gain significant direction dependence and
+that the fractional direction dependence of the tensor power spectrum is
+suppressed in comparison to that of the scalar power spectrum.",1001.2301v4
+2010-01-14,Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves,"The Apache Point Lunar Laser-ranging Operation (APOLLO), in NM, can detect
+photon bounces from retro-reflectors on the moon surface to 0.1ns timing
+resolution. This facility enables not only the detection of light speed
+anisotropy, which defines a local preferred frame of reference - only in that
+frame is the speed of light isotropic, but also fluctuations/turbulence
+(gravitational waves) in the flow of the dynamical 3-space relative to local
+systems/observers. So the APOLLO facility can act as an effective
+""gravitational wave"" detector. A recently published small data set from
+November 5, 2007, is analysed to characterise both the average anisotropy
+velocity and the wave/turbulence effects. The results are consistent with some
+13 previous detections, with the last and most accurate being from the
+spacecraft earth-flyby Doppler-shift NASA data.",1001.2358v2
+2010-01-22,Non-Gaussianity and statistical anisotropy from vector field populated inflationary models,"We present a review of vector field models of inflation and, in particular,
+of the statistical anisotropy and non-Gaussianity predictions of models with
+SU(2) vector multiplets. Non-Abelian gauge groups introduce a richer amount of
+predictions compared to the Abelian ones, mostly because of the presence of
+vector fields self-interactions. Primordial vector fields can violate isotropy
+leaving their imprint in the comoving curvature fluctuations zeta at late
+times. We provide the analytic expressions of the correlation functions of zeta
+up to fourth order and an analysis of their amplitudes and shapes. The
+statistical anisotropy signatures expected in these models are important and,
+potentially, the anisotropic contributions to the bispectrum and the
+trispectrum can overcome the isotropic parts.",1001.4049v1
+2010-01-25,"Interplay between Symmetric Exchange Anisotropy, Uniform Dzyaloshinskii-Moriya Interaction and Magnetic Fields in the Phase Diagram of Quantum Magnets and Superconductors","We theoretically study the joint influence of uniform Dzyaloshinskii-Moriya
+(DM) interactions, symmetric exchange anisotropy (with its axis parallel to the
+DM vector) and arbitrarily oriented magnetic fields on one-dimensional spin 1/2
+antiferromagnets. We show that the zero-temperature phase diagram contains
+three competing phases: (i) an antiferromagnet with Neel vector in the plane
+spanned by the DM vector and the magnetic field, (ii) a {\em dimerized}
+antiferromagnet with Neel vector perpendicular to both the DM vector and the
+magnetic field, and (iii) a gapless Luttinger liquid. Phase (i) is destroyed by
+a small magnetic field component along the DM vector and is furthermore
+unstable beyond a critical value of easy-plane anisotropy, which we estimate
+using Abelian and non-Abelian bosonization along with perturbative
+renormalization group. We propose a mathematical equivalent of the spin model
+in a one-dimensional Josephson junction (JJ) array located in proximity to a
+bulk superconductor.
+  We discuss the analogues of the magnetic phases in the superconducting
+context and comment on their experimental viability.",1001.4290v1
+2010-02-10,"Strain, magnetic anisotropy, and anisotropic magnetoresistance in (Ga,Mn)As on high-index substrates: application to (113)A-oriented layers","Based on a detailed theoretical examination of the lattice distortion in
+high-index epilayers in terms of continuum mechanics, expressions are deduced
+that allow the calculation and experimental determination of the strain tensor
+for (hhl)-oriented (Ga,Mn)As layers. Analytical expressions are derived for the
+strain-dependent free-energy density and for the resistivity tensor for
+monoclinic and orthorhombic crystal symmetry, phenomenologically describing the
+magnetic anisotropy (MA) and anisotropic magnetoresistance (AMR) by appropriate
+anisotropy and resistivity parameters, respectively. Applying the results to
+(113)A orientation with monoclinic crystal symmetry, the expressions are used
+to determine the strain tensor and the shear angle of a series of
+(113)A-oriented (Ga,Mn)As layers by high-resolution x-ray diffraction and to
+probe the MA and AMR at 4.2 K by means of angle-dependent magnetotransport.
+Whereas the transverse resistivity parameters are nearly unaffected by the
+magnetic field, the parameters describing the longitudinal resistivity are
+strongly field dependent.",1002.2179v2
+2010-02-11,"Synthesis, anisotropy, and superconducting properties of LiFeAs single crystal","A LiFeAs single crystal with $T_c^{onset}$$\sim$19.7 K was grown successfully
+in a sealed tungsten crucible using the Bridgeman method. The electrical
+resistivity experiments revealed a ratio of room temperature to residual
+resistivity (RRR) of approximately 46 and 18 for the in-plane and out-of plane
+directions. The estimated anisotropic resistivity, $\gamma_\rho$=$\rho_c$ /
+$\rho_{ab}$, was approximately 3.3 at $T_c^{onset}$. The upper critical fields
+had large $H_{c2} ^{\shortparallel ab}$ and $H_{c2}^{\shortparallel c}$ values
+of 83.4 T and 72.5 T, respectively, and an anisotropy ratio is
+$\gamma_H$=$H_{c2}^{\shortparallel ab}$ / $H_{c2} ^{\shortparallel
+c}$$\sim$1.15. The high upper critical field value and small anisotropy
+highlight the potential use of LiFeAs in a variety of applications. The
+calculated critical current density $(J_c)$ from the $M$-$H$ loop is
+approximately 10$^3$ A/cm$^2$",1002.2249v1
+2010-02-12,Low magnetization and anisotropy in the antiferromagnetic state of undoped iron pnictides,"We examine the magnetic phase diagram of iron pnictides using a five band
+model. For the intermediate values of the interaction expected to hold in the
+iron pnictides, we find a metallic low moment state characterized by
+antiparallel orbital magnetic moments. The anisotropy of the interorbital
+hopping amplitudes is the key to understanding this low moment state. This
+state accounts for the small magnetization measured in undoped iron pnictides
+and leads to the strong exchange anisotropy found in neutron experiments.
+Orbital ordering is concomitant with magnetism and produces the large zx
+orbital weight seen at Gamma in photoemission experiments.",1002.2584v2
+2010-02-20,Analytic formulae for CMB anisotropy in LTB cosmology,"The local void model has lately attracted considerable attention since it can
+explain the present apparent accelerated expansion of the universe without
+introducing dark energy. However, in order to justify this model as an
+alternative cosmological model to the standard $\Lambda$CDM model (FLRW
+universe plus dark energy), one has to test the model by various observations,
+such as CMB temperature anisotropy, other than the distance-redshift relation
+of SNIa. For this purpose, we derive some analytic formulae that can be used to
+rigorously compare consequences of this model with observations of CMB
+anisotropy and to place constraints on the position of observers in the void
+model.",1002.3855v3
+2010-02-24,Role of anisotropy for protein-protein encounter,"Protein-protein interactions comprise both transport and reaction steps.
+During the transport step, anisotropy of proteins and their complexes is
+important both for hydrodynamic diffusion and accessibility of the binding
+site. Using a Brownian dynamics approach and extensive computer simulations, we
+quantify the effect of anisotropy on the encounter rate of ellipsoidal
+particles covered with spherical encounter patches. We show that the encounter
+rate $k$ depends on the aspect ratios $\xi$ mainly through steric effects,
+while anisotropic diffusion has only a little effect. Calculating analytically
+the crossover times from anisotropic to isotropic diffusion in three
+dimensions, we find that they are much smaller than typical protein encounter
+times, in agreement with our numerical results.",1002.4485v1
+2010-02-24,Monte Carlo Study of Maghemite Nanoparticles,"We consider a simple model of maghemite nanoparticles and study their
+magnetic properties using Monte Carlo methods. The particles have a spherical
+geometry with diameters ranging from 3 nm to 8 nm. The interior of the
+particles consists of core spins with exchange interactions and anisotropy
+given by the values in the bulk material. The outer layer of the particles
+consists of surface spins with weaker exchange interactions but an enhanced
+anisotropy. The thermal behaviour of the total, core and surface magnetizations
+are calculated as well as the hysteresis loops due to the application of an
+applied field. The effect of the surface anisotropy on the blocking
+temperature, the coercive and exchange bias fields is studied.",1002.4648v2
+2010-02-25,Statistical anisotropy as a consequence of inflation,"Cosmological inflation remains to be a unique mechanism of generation of
+plausible initial conditions in the early universe. In particular, it generates
+the primordial quasiclassical perturbations with power spectrum determined by
+the fundamental principles of quantum field theory. In this work, we pay
+attention to the fact that the quasiclassical perturbations permanently
+generated at early stages of inflation break homogeneity and isotropy of the
+cosmological background. The evolution of the small-scale quantum vacuum modes
+on this inhomogeneous background results in statistical anisotropy of the
+primordial power spectrum, which can manifest itself in the observable
+large-scale structure and cosmic microwave background. The effect is predicted
+to have almost scale-invariant form dominated by a quadrupole and may serve as
+a non-trivial test of the inflationary scenario. Theoretical expectation of the
+magnitude of this statistical anisotropy depends on the assumptions about the
+physics in the trans-Planckian region of wavenumbers.",1002.4879v1
+2010-02-27,The Nature of Primordial Fluctuations from Anisotropic Inflation,"We study the statistical nature of primordial fluctuations from an
+anisotropic inflation which is realized by a vector field coupled to an
+inflaton. We find a suitable gauge, which we call the canonical gauge, for
+anisotropic inflation by generalizing the flat slicing gauge in conventional
+isotropic inflation. Using the canonical gauge, we reveal the structure of the
+couplings between curvature perturbations, vector waves, and gravitational
+waves. We identify two sources of anisotropy, i.e. the anisotropy due to the
+anisotropic expansion of the universe and that due to the anisotropic couplings
+among variables. It turns out that the latter effect is dominant. Since the
+coupling between the curvature perturbations and vector waves is the strongest
+one, the statistical anisotropy in the curvature perturbations is larger than
+that in gravitational waves. We find the cross correlation between the
+curvature perturbations and gravitational waves which never occurs in
+conventional inflation. We also find the linear polarization of gravitational
+waves. Finally, we discuss cosmological implication of our results.",1003.0056v2
+2010-03-11,Correlations between the proton temperature anisotropy and transverse high-frequency waves in the solar wind,"Correlations are studied between the power density of transverse waves having
+frequencies between $0.01$ and $1$ normalized to the proton gyrofrequency in
+the plasma frame and the ratio of the perpendicular and parallel temperature of
+the protons. The wave power spectrum is evaluated from high-resolution 3D
+magnetic field vector components, and the ion temperatures are derived from the
+velocity distribution functions as measured in fast solar wind during the
+Helios-2 primary mission at radial distances from the Sun between 0.3~AU and
+0.9~AU. From our statistical analysis, we obtain a striking correlation between
+the increases in the proton temperature ratio and enhancements in the wave
+power spectrum. Near the Sun the transverse part of the wave power is often
+found to be by more than an order of magnitude higher than its longitudinal
+counterpart. Also the measured ion temperature anisotropy appears to be limited
+by the theoretical threshold value for the ion-cyclotron instability. This
+suggests that high-frequency Alfv\'{e}n-cyclotron waves regulate the proton
+temperature anisotropy.",1003.2299v2
+2010-03-26,Anisotropic electron spin resonance of YbIr2Si2,"A series of electron spin resonance (ESR) experiments were performed on a
+single crystal of the heavy fermion metal YbIr2Si2 to map out the anisotropy of
+the ESR-intensity I_ESR which is governed by the microwave field component of
+the g-factor. The temperature dependencies of I_ESR(T) and g(T) were measured
+for different orientations and compared within the range 2.6K \le T \le 16K.
+The analysis of the intensity dependence on the crystal orientation with
+respect to both the direction of the microwave field and the static magnetic
+field revealed remarkable features: The intensity variation with respect to the
+direction of the microwave field was found to be one order of magnitude smaller
+than expected from the g-factor anisotropy. Furthermore, we observed a weak
+basal plane anisotropy of the ESR parameters which we interpret to be an
+intrinsic sample property.",1003.5133v1
+2010-03-30,Stability of a strongly anisotropic thin epitaxial film in a wetting interaction with elastic substrate,"The linear dispersion relation for longwave surface perturbations, as derived
+by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth
+surface energy anisotropy function with a variable anisotropy strength (from
+weak to strong, such that sharp corners and slightly curved facets occur on the
+corresponding Wulff shape). Through detailed parametric studies it is shown
+that a combination of a wetting interaction and strong anisotropy, and even a
+wetting interaction alone results in complicated linear stability
+characteristics of strained and unstrained films. PACS: 68.55.J, Morphology of
+films; 81.15.Aa, Theory and models of film growth; 81.16.Dn, Self-assembly.",1003.5806v5
+2010-04-06,Electron spin resonance in S=1/2 antiferromagnets at high temperature,"We study the electron spin resonance (ESR) of low-dimensional spin systems at
+high temperature, and test the Kubo-Tomita theory of exchange narrowing. In
+finite-size systems (molecular magnets), we found a double-peak resonance which
+strongly differs from the usual Lorentzian. For infinite systems, we have
+predictions for the linewidth and lineshape as a function of the anisotropy
+strength. For this, we have used an interpolation between a non-perturbative
+calculation of the memory function at short times (exact diagonalization) and
+the hydrodynamic spin-diffusion at long times. We show that the
+Dzyaloshinskii-Moriya anisotropies generally induce a much larger linewidth
+than the exchange anisotropies in two dimensions, contrary to the
+one-dimensional case.",1004.0839v1
+2010-04-20,Electronic transport in an anisotropic Sierpinski gasket,"We present exact results on certain electronic properties of an anisotropic
+Sierpinski gasket fractal. We use a tight binding Hamiltonian and work within
+the formalism of a real space renormalization group (RSRG) method. The
+anisotropy is introduced in the values of the nearest neighbor hopping
+integrals. An extensive numerical examination of the two terminal transmission
+spectrum and the flow of the hopping integrals under the RSRG iterations
+strongly suggest that an anisotropic gasket is more conducting than its
+isotropic counter part and that, even a minimal anisotropy in the hopping
+integrals generate {\it continuous bands} of eigenstates in the spectrum for
+finite Sierpinski gaskets of arbitrarily large size. We also discuss the effect
+of a magnetic field threading the planar gasket on its transport properties and
+calculate the persistent current in the system. The sensitivity of the
+persistent current on the anisotropy and on the band filling is also discussed.",1004.3353v1
+2010-04-23,Critical current scaling and anisotropy in oxypnictide superconductors,"Investigating the anisotropy of superconductors permits an access to
+fundamental properties. Having succeeded in the fabrication of epitaxial
+superconducting LaFeAs(O,F) thin films we performed an extensive study of
+electrical transport properties. In face of multiband superconductivity we can
+demonstrate that a Blatter scaling of the angular dependent critical current
+densities can be adopted, although being originally developed for single band
+superconductors. In contrast to single band superconductors the mass anisotropy
+of LaFeAs(O,F) is temperature dependent. A very steep increase of the upper
+critical field and the irreversibility field can be observed at temperatures
+below 6K, indicating that the band with the smaller gap is in the dirty limit.
+This temperature dependence can be theoretically described by two dominating
+bands responsible for superconductivity. A pinning force scaling provides
+insight into the prevalent pinning mechanism and can be specified in terms of
+the Kramer model.",1004.4185v1
+2010-04-24,Six-fold in-plane magnetic anisotropy in Co-implanted ZnO (0001),"Magnetic anisotropies of Co-implanted ZnO (0001) films grown on
+single-crystalline Al2O3 (11-20) substrates have been studied by ferromagnetic
+resonance (FMR) technique for different cobalt implantation doses. The FMR data
+show that the easy and hard axes have a periodicity of 60 degrees in the film
+plane, in agreement with the hexagonal structure of the ZnO films. This
+six-fold in-plane magnetic anisotropy, which is observed for the first time in
+ZnO-based diluted magnetic semiconductors, is attributed to the substitution of
+cobalt on Zn sites in the ZnO structure, and a clear indication for long range
+ferromagnetic ordering between substitutional cobalt ions in the
+single-crystalline ZnO films.",1004.4291v1
+2010-05-12,Stripe antiferromagnetic correlations in LaFeAsO1-xFx probed by 75As NMR,"The anisotropy of the nuclear spin-lattice relaxation rate $1/T_{1}$ of
+$^{75}$As was investigated in the iron-based superconductor
+LaFeAs(O$_{1-x}$F$_{x}$) ($x = 0.07, 0.11$ and 0.14) as well as LaFeAsO. While
+the temperature dependence of the normal-state $1/T_1T$ in the superconducting
+(SC) $x = 0.07$ is different from that in the SC $x = 0.11$, their anisotropy
+of $1/T_1$, $R \equiv (1/T_{1})_{H \parallel ab}/(1/T_{1})_{H \parallel c}$ in
+the normal state is almost the same ($\simeq$ 1.5). The observed anisotropy is
+ascribable to the presence of the local stripe correlations with $Q = (\pi, 0)$
+or $(0, \pi)$. In contrast, $1/T_1$ is isotropic and $R$ is approximately 1 in
+the overdoped $x = 0.14$ sample, where superconductivity is almost suppressed.
+These results suggest that the presence of the local stripe correlations
+originating from the nesting between hole and electron Fermi surfaces is linked
+to high-$T_c$ superconductivity in iron pnictides.",1005.2013v2
+2010-05-12,Striped-magnetic-order suppresses giant optical anisotropy and drives structural distortion in iron arsenide superconductors,"To examine the role of magnetism in superconductivity of iron-based
+superconductors, we first present first-principles optical calculations on
+three representative parent compounds: LaFeAsO, BaFe2As2 and LiFeAs. Both
+nonmagnetic (NM) and spin-density wave (SDW) with striped antiferromagnetic
+order are considered. Due to their layer structure, these compounds in NM
+states show anomalously large optical anisotropy with a conductivity ratio
+$\sigma_{zz}/\sigma{xx}$ as large as 313% in LaFeAsO and 530% in LiFeAs.
+Interestingly the giant optical anisotropy is significantly suppressed by SDW.
+On the other hand, the variable-cell-shape optimizations confirm that SDW does
+drive an orthorhombic-distortion. The drive force is dependent on the local
+magnetic moment on Fe sublattice, which is tuned by its bonding environment.
+Based on these results, we discussed the delicate role of magnetism in
+superconductivity.",1005.2121v2
+2010-05-17,Confinement-induced resonance in quasi-one-dimensional systems under transversely anisotropic confinement,"We theoretically investigate the confinement-induced resonance for
+quasi-one-dimensional quan- tum systems under transversely anisotropic
+confinement, using a two-body s-wave scattering model in the zero-energy
+collision limit. We predict a single resonance for any transverse anisotropy,
+whose position shows a slight downshift with increasing anisotropy. We compare
+our prediction with the recent experimental result by Haller et al. [Phys. Rev.
+Lett. 104, 153203 (2010)], in which two resonances are observed in the presence
+of transverse anisotropy. The discrepancy between theory and experiment remains
+to be resolved.",1005.2794v2
+2010-05-17,Measurement of the Anisotropy of Cosmic Ray Arrival Directions with IceCube,"We report the first observation of an anisotropy in the arrival direction of
+cosmic rays with energies in the multi TeV region in the Southern sky using
+data from the IceCube detector. Between June 2007 and March 2008, the
+partially-deployed IceCube detector was operated in a configuration with 1320
+digital optical sensors distributed over 22 strings at depths between 1450 and
+2450 meters inside the Antarctic ice. IceCube is a neutrino detector, but the
+data are dominated by a large background of cosmic ray muons. Therefore, the
+background data are suitable for high-statistics studies of cosmic rays in the
+Southern sky. The data include 4.3 billion muons produced by downgoing cosmic
+ray interactions in the atmosphere; these events were reconstructed with a
+median angular resolution of 3 degrees and a median energy of $\sim20$ TeV.
+Their arrival direction distribution exhibits an anisotropy in right ascension
+with a first harmonic amplitude of $(6.4\pm0.2 $stat$. \pm 0.8
+$syst$.)\times10^{-4}$.",1005.2960v1
+2010-05-27,Azimuthal anisotropy: transition from hydrodynamic flow to jet suppression,"Measured 2nd and 4th azimuthal anisotropy coefficients v_{2,4}(N_{part}),
+p_T) are scaled with the initial eccentricity \varepsilon_{2,4}(N_{part}) of
+the collision zone and studied as a function of the number of participants
+N_{part} and the transverse momenta p_T. Scaling violations are observed for
+$p_T \alt 3$ GeV/c, consistent with a $p_T^2$ dependence of viscous corrections
+and a linear increase of the relaxation time with $p_T$. These empirical
+viscous corrections to flow and the thermal distribution function at freeze-out
+constrain estimates of the specific viscosity and the freeze-out temperature
+for two different models for the initial collision geometry. The apparent
+viscous corrections exhibit a sharp maximum for $p_T \agt 3$ GeV/c, suggesting
+a breakdown of the hydrodynamic ansatz and the onset of a change from
+flow-driven to suppression-driven anisotropy.",1005.4979v2
+2010-06-14,"Tuning perpendicular magnetic anisotropy in (Ga,Mn)(As,P) by thermal annealing","We have investigated the effects of post growth low temperature annealing on
+the magnetic, electrical and structural properties of
+(Ga_0.94,Mn_0.06)(As_0.9,P_0.1) layers grown by molecular beam epitaxy. By
+controlling the annealing time we are able to tune the magnetic anisotropy
+between an easy axis in the plane for the as-grown samples, to an easy axis
+perpendicular to the plane for fully annealed samples. The increase of the
+carrier density, as a result of annealing, is found to be the primary reason
+for the change in magnetic anisotropy, in qualitative agreement with
+theoretical predictions.",1006.2644v1
+2010-06-29,Magnetic properties of exchange biased and of unbiased oxide/permalloy thin layers: a ferromagnetic resonance and Brillouin scattering study,"Microstrip ferromagnetic resonance and Brillouin scattering are used to
+provide a comparative determination of the magnetic parameters of thin
+permalloy layers interfaced with a non-magnetic (Al2O3) or with an
+antiferromagnetic oxide (NiO). It is shown that the perpendicular anisotropy is
+monitored by an interfacial surface energy term which is practically
+independent of the nature of the interface. In the investigated interval of
+thicknesses (5-25 nm) the saturation magnetisation does not significantly
+differ from the reported one in bulk permalloy. In-plane uniaxial anisotropy
+and exchange-bias anisotropy are also derived from this study of the dynamic
+magnetic excitations and compared to our independent evaluations using
+conventional magnetometry",1006.5598v1
+2010-07-06,Dissipative Dynamics of Highly Anisotropic Systems,"In this paper we present a method to improve the description of 0+1
+dimensional boost invariant dissipative dynamics in the presence of large
+momentum-space anisotropies. We do this by reorganizing the canonical
+hydrodynamic expansion of the distribution function around a momentum-space
+anisotropic ansatz rather than an isotropic equilibrium one. At leading order
+the result obtained is two coupled ordinary differential equations for the
+momentum-space anisotropy and typical momentum of the degrees of freedom. We
+show that this framework can reproduce both the ideal hydrodynamic and free
+streaming limits. Additionally, we demonstrate that when linearized the
+differential equations reduce to 2nd order Israel-Stewart viscous
+hydrodynamics. Finally, we make quantitative comparisons of the evolution of
+the pressure anisotropy within our approach and 2nd order viscous hydrodynamics
+in both the strong and weak coupling limits.",1007.0889v3
+2010-07-21,Exchange anisotropy pinning of a standing spin wave mode,"Standing spin waves in a thin film are used as sensitive probes of interface
+pinning induced by an antiferromagnet through exchange anisotropy. Using
+coplanar waveguide ferromagnetic resonance, pinning of the lowest energy spin
+wave thickness mode in Ni(80)Fe(20)/Ir(25)Mn(75) exchange biased bilayers was
+studied for a range of IrMn thicknesses. We show that pinning of the standing
+mode can be used to amplify, relative to the fundamental resonance, frequency
+shifts associated with exchange bias. The shifts provide a unique `fingerprint'
+of the exchange bias and can be interpreted in terms of an effective
+ferromagnetic film thickness and ferromagnet/antiferromagnet interface
+anisotropy. Thermal effects are studied for ultra-thin antiferromagnetic
+Ir(25)Mn(75) thicknesses, and the onset of bias is correlated with changes in
+the pinning fields. The pinning strength magnitude is found to grow with
+cooling of the sample, while the effective ferromagnetic film thickness
+simultaneously decreases. These results suggest that exchange bias involves
+some deformation of magnetic order in the interface region.",1007.3577v1
+2010-08-10,Magnetic anisotropy effects on quantum impurities in superconducting host,"We study the magnetic anisotropy effects on the localized sub-gap excitations
+induced by quantum impurities coupled to a superconducting host. We establish
+the ground-state phase diagrams for single-channel and two-channel high-spin
+Kondo impurities; they unveil surprising complexity that results from the
+(multi-stage) Kondo screening in competition with the superconducting
+correlations and the magnetic anisotropy splitting of the spin multiplets. We
+discuss the possibility of detecting the Zeeman splitting of the sub-gap
+states, which would provide an interesting spectroscopic tool for studying the
+magnetism on the single-atom level. We also study the problem of two impurities
+coupled by the Heisenberg exchange interaction, and we follow the evolution of
+the sub-gap states for both antiferromagnetic and ferromagnetic coupling. For
+sufficiently strong antiferromagnetic coupling, the impurities bind into a
+singlet state that is non-magnetic, thus the sub-gap states move to the edge of
+the gap and can no longer be discerned. For ferromagnetic coupling, some
+excited states remain present inside the gap.",1008.1734v2
+2010-08-20,Morphological diagram of diffusion driven aggregate growth in plane: competition of anisotropy and adhesion,"Two-dimensional structures grown with Witten and Sander algorithm are
+investigated. We analyze clusters grown off-lattice and clusters grown with
+antenna method with $N_{fp}=3,4,5,6,7$ and 8 allowed growth directions. With
+the help of variable probe particles technique we measure fractal dimension of
+such clusters $D(N)$ as a function of their size $N$. We propose that in the
+thermodynamic limit of infinite cluster size the aggregates grown with high
+degree of anisotropy ($N_{fp}=3,4,5$) tend to have fractal dimension $D$ equal
+to 3/2, while off-lattice aggregates and aggregates with lower anisotropy
+($N_{fp}>6$) have $D \approx 1.710$. Noise-reduction procedure results in the
+change of universality class for DLA. For high enough noise-reduction value
+clusters with $N_{fp} \ge 6$ have fractal dimension going to $3/2$ when
+$N\rightarrow\infty$.",1008.3449v1
+2010-09-03,"Free energies, vacancy concentrations and density distribution anisotropies in hard--sphere crystals: A combined density functional and simulation study","We perform a comparative study of the free energies and the density
+distributions in hard sphere crystals using Monte Carlo simulations and density
+functional theory (employing Fundamental Measure functionals). Using a recently
+introduced technique (Schilling and Schmid, J. Chem. Phys 131, 231102 (2009))
+we obtain crystal free energies to a high precision. The free energies from
+Fundamental Measure theory are in good agreement with the simulation results
+and demonstrate the applicability of these functionals to the treatment of
+other problems involving crystallization. The agreement between FMT and
+simulations on the level of the free energies is also reflected in the density
+distributions around single lattice sites. Overall, the peak widths and
+anisotropy signs for different lattice directions agree, however, it is found
+that Fundamental Measure theory gives slightly narrower peaks with more
+anisotropy than seen in the simulations. Among the three types of Fundamental
+Measure functionals studied, only the White Bear II functional (Hansen-Goos and
+Roth, J. Phys.: Condens. Matter 18, 8413 (2006)) exhibits sensible results for
+the equilibrium vacancy concentration and a physical behavior of the chemical
+potential in crystals constrained by a fixed vacancy concentration.",1009.0613v1
+2010-09-13,Lateral Confinement of Electrons in Vicinal N-polar AlGaN/GaN Heterostructure,"We studied orientation dependent transport in vicinal N-polar AlGaN/GaN
+heterostructures. We observed significant anisotropy in the current carrying
+charge parallel and perpendicular to the miscut direction. A quantitative
+estimate of the charge anisotropy was made based on gated TLM and Hall
+measurements. The formation of electro-statically confined one-dimensional
+channels is hypothesized to explain charge anisotropy. A mathematical model was
+used to verify that polarization charges distributed on miscut structure can
+create lateral one-dimensional confinement in vicinal substrates. This
+polarization-engineered electrostatic confinement observed is promising for new
+research on low-dimensional physics and devices besides providing a template
+for manufacturable one-dimensional devices.",1009.2537v1
+2010-09-29,Transference of Transport Anisotropy to Composite Fermions,"When interacting two-dimensional electrons are placed in a large
+perpendicular magnetic field, to minimize their energy, they capture an even
+number of flux quanta and create new particles called composite fermions (CFs).
+These complex electron-flux-bound states offer an elegant explanation for the
+fractional quantum Hall effect. Furthermore, thanks to the flux attachment, the
+effective field vanishes at a half-filled Landau level and CFs exhibit
+Fermi-liquid-like properties, similar to their zero-field electron
+counterparts. However, being solely influenced by interactions, CFs should
+possess no memory whatever of the electron parameters. Here we address a
+fundamental question: Does an anisotropy of the electron effective mass and
+Fermi surface (FS) survive composite fermionization? We measure the resistance
+of CFs in AlAs quantum wells where electrons occupy an elliptical FS with large
+eccentricity and anisotropic effective mass. Similar to their electron
+counterparts, CFs also exhibit anisotropic transport, suggesting an anisotropy
+of CF effective mass and FS.",1009.5732v1
+2010-10-04,Observation of mixed anisotropy in the critical susceptibility of an ultrathin magnetic film,"Measurements of the magnetic susceptibility of Fe/W(110) films with thickness
+in the range of 1.6 to 2.4 ML Fe, show that in addition to the large response
+along the easy axis associated with the Curie transition, there is a much
+smaller, paramagnetic hard axis response that is not consistent with the 2D
+anisotropic Heisenberg model used to describe homogeneous in-plane ferromagnets
+with uniaxial anisotropy. The shape, amplitude, and peak temperature of the
+hard axis susceptibility, as well as its dependence upon layer completion close
+to 2.0 ML, indicate that inhomogeneities in the films create a system of mixed
+anisotropy. A likely candidate for inhomogeneities that are magnetically
+relevant in the critical region are the closed lines of step edges associated
+with the incomplete layers. According to the Harris criterion, the existence of
+magnetically relevant inhomogeneities may alter the critical properties of the
+films from those of a 2D Ising model. Experiments in the recent literature are
+discussed in this context.",1010.0657v2
+2010-10-05,Large Scale Traces of Solar System Cold Dust on CMB Anisotropies,"We explore the microwave anisotropies at large angular scales produced by the
+emission from cold and large dust grains, expected to exist in the outer parts
+of the Solar System, using a simple toy model for this diuse emission. Its
+amplitude is constrained in the Far-IR by the COBE data and is compatible with
+simulations found in the literature. We analyze the templates derived after
+subtracting our model from the WMAP ILC 7 yr maps and investigate on the
+cosmological implications of such a possible foreground. The anomalies related
+to the low quadrupole of the angular power spectrum, the two-point correlation
+function, the parity and the excess of signal found in the ecliptic plane are
+significantly alleviated. An impact of this foreground for some cosmological
+parameters characterizing the spectrum of primordial density perturbations,
+relevant for on-going and future CMB anisotropy experiments, is found.",1010.0830v2
+2010-10-12,Atomistic spin-model based on a new spin-cluster expansion technique: Application to the IrMn3/Co interface,"In order to derive tensorial exchange interactions and local magnetic
+anisotropies in itinerant magnetic systems, an approach combining the
+Spin-Cluster Expansion with the Relativistic Disordered Local Moment scheme is
+introduced. The theoretical background and computational aspects of the method
+are described in detail. The exchange interactions and site resolved anisotropy
+contributions for the IrMn3/Co(111) interface, a prototype for an exchange bias
+system, are calculated including a large number of magnetic sites from both the
+antiferromagnet and ferromagnet. Our calculations reveal that the coupling
+between the two subsystems is fairly limited to the vicinity of the interface.
+The magnetic anisotropy of the interface system is discussed, including effects
+of the Dzyaloshinskii-Moriya interactions that appear due to symmetry breaking
+at the interface.",1010.2375v1
+2010-10-14,Theory of Orbital Nematicity in Underdoped Iron Arsenides,"Recent finding of an {\it unusual} in-plane resistivity anisotropy in the
+underdoped 122-family at high temperature ($T$) suggests an orbital nematic
+(ON) order, posing a challenge to extant theories. The {\it sign} of the
+anisotropy contradicts expectations from weakly correlated as well as pure
+spin-only nematic views. Here, we show how such an ON order with accompanying
+structural distortion arises from {\it residual}, intersite and inter-orbital
+two-body interactions in an incoherent ""bad metal"" close to Mottness.
+Enhancement of orbital-selective incoherence is shown to be necessary for
+understanding transport anisotropy. Our results suggest that ON order, with
+subsequent antiferromagnetic order might be the {\it primary} competitor to
+superconductivity in Fe arsenides.",1010.2940v1
+2010-10-22,"Single-ion anisotropy, Dzyaloshinskii-Moriya interaction and negative magnetoresistance of the spin-1/2 pyrochlores R2V2O7","The electronic and magnetic properties of spin-1/2 pyrochlores R2V2O7 were
+investigated on the basis of density-functional calculations. Contrary to the
+common belief, the spin-1/2 V4+ ions are found to have a substantial easy-axis
+single-ion anisotropy. The |D/J| ratio deduced from the magnon quantum Hall
+effect of Lu2V2O7, where J is the nearest-neighbor spin exchange and D is the
+Dzyaloshinskii-Moriya parameter, is much greater than the value estimated from
+our calculations (i.e., 0.32 vs. 0.05). We show that this discrepancy is due to
+the neglect of the single-ion anisotropy of the V4+ ions, and the negative
+magnetoresistance observed for R2V2O7 arises from a new mechanism.",1010.4606v1
+2010-10-22,"Investigation on Anharmonicity, Vibrational Anisotropy and Thermal Expansion of an Amorphous Ni$_{46}$Ti$_{54}$ Alloy Produced by Mechanical Alloying using Extended X-ray Absorption Fine Structure","A method to investigate anharmonicity, vibrational anisotropy and thermal
+expansion using correlated mean-square relative displacements (MSRD) parallel
+and perpendicular to the interatomic bonds obtained only from Extended X-ray
+Absorption Fine Structure (EXAFS) analysis based on cumulant expansion is
+suggested and applied to an amorphous Ni$_{46}$Ti$_{54}$ alloy produced by
+mechanical alloying. From EXAFS measurements taken on Ni and Ti K edges at
+several temperatures, the thermal behavior of $\text{MSRD}_\parallel$,
+$\text{MSRD}_\perp$ and of the cumulants $C_1^*$, $C_2^*$ and $C_3^*$ of the
+real distribution functions $\varrho_{ij}(r,T)$, and also the Einstein
+temperatures and frequencies associated with parallel and perpendicular motion
+were obtained, furnishing information about the anharmonicity of the
+interatomic potential, vibrational anisotropy and the contribution of the
+perpendicular motion to the total disorder and thermal expansion.",1010.4703v1
+2010-10-26,Single domain to multi-domain transition due to in-plane magnetic anisotropy in phase separated (La$_{0.4}$Pr$_{0.6}$)$_{0.67}$Ca$_{0.33}$MnO$_{3}$ thin films,"Phase separated perovskite manganites have competing phases with different
+crystal structures, magnetic and electronic properties. Hence, strain effects
+play a critical role in determining the magnetic properties of manganite thin
+films. Here we report the effect of anisotropic stress on the magnetic
+properties of the phase separated manganite
+(La$_{0.4}$Pr$_{0.6}$)$_{0.67}$Ca$_{0.33}$MnO$_{3}$. Thin films of
+(La$_{0.4}$Pr$_{0.6}$)$_{0.67}$Ca$_{0.33}$MnO$_{3}$ grown under anisotropic
+in-plane stress on (110) NdGaO$_{3}$ substrates display in-plane mangetic
+anisotropy and single domain to multidomain transition as a function of
+temperature. Angle dependent magnetization measurements also show that the
+magnetization reversal occurs mainly through the nucleation $&$ propagation
+mechanism. By comparing the results with
+(La$_{0.4}$Pr$_{0.6}$)$_{0.67}$Ca$_{0.33}$MnO$_{3}$ thin films grown on (001)
+SrLaGaO$_{4}$ substrates, we have confirmed that the magnetic anisotropy is
+mainly due to substrate induced anisotropic stress. Our results suggest novel
+avenues for storing magnetic information in nanoscale magnetic media.",1010.5482v1
+2010-11-01,Optimization of artificial flockings by means of anisotropy measurements,"An effective procedure to determine the optimal parameters appearing in
+artificial flockings is proposed in terms of optimization problems. We
+numerically examine genetic algorithms (GAs) to determine the optimal set of
+parameters such as the weights for three essential interactions in BOIDS by
+Reynolds (1987) under `zero-collision' and `no-breaking-up' constraints. As a
+fitness function (the energy function) to be maximized by the GA, we choose the
+so-called the $\gamma$-value of anisotropy which can be observed empirically in
+typical flocks of starling. We confirm that the GA successfully finds the
+solution having a large $\gamma$-value leading-up to a strong anisotropy. The
+numerical experience shows that the procedure might enable us to make more
+realistic and efficient artificial flocking of starling even in our personal
+computers. We also evaluate two distinct types of interactions in agents,
+namely, metric and topological definitions of interactions. We confirmed that
+the topological definition can explain the empirical evidence much better than
+the metric definition does.",1011.0362v2
+2010-11-12,Non-boost-invariant anisotropic dynamics,"We study the non-boost-invariant evolution of a quark-gluon plasma subject to
+large early-time momentum-space anisotropies. Rather than using the canonical
+hydrodynamical expansion of the distribution function around an isotropic
+equilibrium state, we expand around a state which is anisotropic in momentum
+space and parameterize this state in terms of three proper-time and
+spatial-rapidity dependent parameters. Deviations from the Bjorken scaling
+solutions are naturally taken into account by the time evolution of the
+spatial-rapidity dependence of the anisotropic ansatz. As a result, we obtain
+three coupled partial differential equations for the momentum-space anisotropy,
+the typical momentum of the degrees of freedom, and the longitudinal flow.
+Within this framework (0+1)-dimensional Bjorken expansion is obtained as an
+asymptotic limit. Finally, we make quantitative comparisons of the temporal and
+spatial-rapidity evolution of the dynamical parameters and resulting pressure
+anisotropy in both the strong and weak coupling limits.",1011.3056v2
+2010-11-17,Interaction anisotropy and random impurities effects on the critical behaviour of ferromagnets,"The theory of phase transitions is based on the consideration of ""idealized""
+models, such as the Ising model: a system of magnetic moments living on a cubic
+lattice and having only two accessible states. For simplicity the interaction
+is supposed to be restricted to nearest--neighbour sites only. For these
+models, statistical physics gives a detailed description of the behaviour of
+various thermodynamic quantities in the vicinity of the transition temperature.
+These findings are confirmed by the most precise experiments. On the other
+hand, there exist other cases, where one must account for additional features,
+such as anisotropy, defects, dilution or any effect that may affect the nature
+and/or the range of the interaction. These features may have impact on the
+order of the phase transition in the ideal model or smear it out. Here we
+address two classes of models where the nature of the transition is altered by
+the presence of anisotropy or dilution.",1011.3923v1
+2010-11-24,Observation of the anisotropy in arrival direction of Cosmic Rays with IceCube,"The IceCube Neutrino Observatory is a kilometer-scale detector currently
+under construction at the South Pole. In its final configuration the detector
+will comprise 5160 Digital Optical Modules (DOMs) deployed on 86 strings
+between 1.5-2.5 km deep within the ice. While still incomplete, the detector
+has already recorded tens of billions of cosmic ray muons with a median energy
+of 20 TeV. This large sample has been used to study the arrival direction
+distribution of the cosmic rays. We report the observation of an anisotropy in
+the cosmic rays arrival direction at two different angular scales. The observed
+large scale anisotropy seems to be a continuation of similar structures
+observed in the Northern Sky by several experiments. IceCube observes also
+significant features on the angular scale of $20^{\circ} - 30^{\circ}$ that
+might be part of the larger scale structure.",1011.5428v1
+2010-12-17,Structural and magnetic properties of Co2MnSi thin films,"Co2MnSi (CMS) films of different thicknesses (20, 50 and 100 nm) were grown
+by radio frequency (RF) sputtering on a-plane sapphire substrates. Our X-rays
+diffraction study shows that, in all the samples, the cubic <110> CSM axis is
+normal to the substrate and that there exist well defined preferential in-plane
+orientations. Static and dynamic magnetic properties were investigated using
+vibrating sample magnetometry (VSM) and micro-strip line ferromagnetic
+resonance (MS-FMR), respectively. From the resonance measurements versus the
+direction and the amplitude of an applied magnetic field we derive most of the
+magnetic parameters: magnetization, gyromagnetic factor, exchange stiffness
+coefficient and magnetic anisotropy terms. The in-plane anisotropy can be
+described as resulting from the superposition of two terms showing a two-fold
+and a four-fold symmetry without necessarily identical principal axes. The
+observed behavior of the hysteresis loops is in agreement with this complex
+form of the in-plane anisotropy",1012.3837v2
+2010-12-21,Antiferromagnetic resonance in ferroborate NdFe$_3$(BO$_3$)$_4,"The AFMR spectra of the NdFe$_3$(BO$_3$)$_4$ crystal are measured in a wide
+range of frequencies and temperatures. It is found that by the type of magnetic
+anisotropy the compound is an ""easy-plane"" antiferromagnet with a weak
+anisotropy in the basal plane. The effective magnetic parameters are
+determined: anisotropy fields $H_{a1}$=1.14 kOe and $H_{a2}$=60 kOe and
+magnetic excitation gaps $\Delta\nu_1$=101.9 GHz and $\Delta \nu_2$=23.8 GHz.
+It is shown that commensurate-incommensurate phase transition causes a shift in
+resonance field and a considerable change in absorption line width.
+  At temperatures below 4.2 K nonlinear regimes of AFMR excitation at low
+microwave power levels are observed.",1012.4588v1
+2011-02-01,Disentangle plume-induced anisotropy in the velocity field in buoyancy-driven turbulence,"We present a method of disentangling the anisotropies produced by the cliff
+structures in turbulent velocity field and test it in the system of turbulent
+Rayleigh-B\'{e}nard (RB) convection. It is found that in the RB system the
+cliff structures in the velocity field are generated by thermal plumes. These
+cliff structures induce asymmetry in the velocity increments, which leads us to
+consider the plus and minus velocity structure functions (VSF). The plus
+velocity increments exclude cliff structures, while the minus ones include
+them. Our results show that the scaling exponents of the plus VSFs are in
+excellent agreement with those predicted for homogeneous and isotropic
+turbulence (HIT), whereas those of the minus VSFs exhibit significant
+deviations from HIT expectations in places where thermal plumes abound. These
+results demonstrate that plus and minus VSFs can be used to quantitatively
+study the effect of cliff structures in the velocity field and to effectively
+disentangle the associated anisotropies caused by these structures.",1102.0098v1
+2011-02-04,An Asymptotic-Preserving method for highly anisotropic elliptic equations based on a micro-macro decomposition,"The concern of the present work is the introduction of a very efficient
+Asymptotic Preserving scheme for the resolution of highly anisotropic diffusion
+equations. The characteristic features of this scheme are the uniform
+convergence with respect to the anisotropy parameter $0<\eps <<1$, the
+applicability (on cartesian grids) to cases of non-uniform and non-aligned
+anisotropy fields $b$ and the simple extension to the case of a non-constant
+anisotropy intensity $1/\eps$. The mathematical approach and the numerical
+scheme are different from those presented in the previous work [Degond et al.
+(2010), arXiv:1008.3405v1] and its considerable advantages are pointed out.",1102.0904v1
+2011-02-20,Electrostriction Effects During Defibrillation,"Background-The electric field applied to the heart during defibrillation
+causes mechanical forces (electrostriction), and as a result the heart deforms.
+This paper analyses the physical origin of the deformation, and how significant
+it is. Methods-We represent the heart as an anisotropic cylinder. This simple
+geometry allows us to obtain analytical solutions for the potential, current
+density, charge, stress, and strain. Results-Charge induced on the heart
+surface in the presence of the electric field results in forces that deform the
+heart. In addition, the anisotropy of cardiac tissue creates a charge density
+throughout the tissue volume, leading to body forces. These two forces cause
+the tissue to deform in a complicated manner, with the anisotropy suppressing
+radial displacements in favor of tangential ones. Quantitatively, the
+deformation of the tissue is small, although it may be significant when using
+some imaging techniques that require the measurement of small displacements.
+Conclusions-The anisotropy of cardiac tissue produces qualitatively new
+mechanical behavior during a strong, defibrillation-strength electric shock.",1102.4077v1
+2011-03-05,Quantum entanglement and teleportation in quantum dot,"We study the thermal entanglement and quantum teleportation using quantum dot
+as a resource. We first consider entanglement of the resource, and then focus
+on the effects of different parameters on the teleportation fidelity under
+different conditions. The critical temperature of disentanglement is obtained.
+Based on Bell measurements in two subspaces, we find the anisotropy
+measurements is optimal to the isotropy arising from the entangled eigenstates
+of the system in the anisotropy subspace. In addition, it is shown that the
+anisotropy transmission fidelity is very high and stable for quantum dot as
+quantum channel when the parameters are adjusted. The possible applications of
+quantum dot are expected in the quantum teleportation.",1103.1000v2
+2011-03-06,"The Influence of Magnetic Anisotropy on the Kondo Effect and Spin-Polarized Transport through Magnetic Molecules, Adatoms and Quantum Dots","Transport properties in the Kondo regime of a nanosystem displaying uniaxial
+magnetic anisotropy (such as a magnetic molecule, magnetic adatom or quantum
+dot coupled to a localized magnetic moment) are analyzed theoretically. In
+particular, the influence of spin-polarized transport through a local orbital
+of the system and exchange coupling of conduction electrons to the system's
+magnetic core on the Kondo effect is discussed. The numerical renormalization
+group method is applied to calculate the spectral functions and linear
+conductance in the case of the parallel and antiparallel configurations of the
+electrodes' magnetic moments. It is shown that both the magnetic anisotropy as
+well as the exchange coupling between electrons tunneling through the
+conducting orbital and magnetic core play an important role in formation of the
+Kondo resonance, leading generally to its suppression. Specific transport
+properties of such a system appear also as a nontrivial behavior of tunnel
+magnetoresistance. It is also shown that the Kondo effect can be restored by an
+external magnetic field in both the parallel and antiparallel magnetic
+configurations.",1103.1128v2
+2011-03-08,Effects of Anisotropy in QED3 from Dyson-Schwinger equations in a box,"We investigate the effect of anisotropies in the fermion velocities of 2+1
+dimensional QED on the critical number N_f^c of fermions for dynamical mass
+generation. Our framework are the Dyson-Schwinger equations for the gauge boson
+and fermion propagators formulated in a finite volume. In contrast to previous
+Dyson-Schwinger studies we do not rely on an expansion in small anisotropies
+but keep the full velocity dependence of fermion equations intact. As result we
+find sizable variations of N_f^c away from the isotropic point in agreement
+with other approaches. We discuss the relevance of our findings for models of
+high-T_c superconductors.",1103.1578v2
+2011-03-25,Temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites,"The temperature dependence of core loss in cobalt substituted Ni-Zn-Cu
+ferrites was investigated. Co2+ ions are known to lead to a compensation of the
+magneto-crystalline anisotropy in Ni-Zn ferrites, at a temperature depending on
+the cobalt content and the Ni/Zn ratio. We observed similar behaviour in
+Ni-Zn-Cu and it was found that the core loss goes through a minimum around this
+magneto-crystalline anisotropy compensation. Moreover, the anisotropy induced
+by the cobalt allowed a strong decrease of core loss, a ferrite having a core
+loss of 350 mW/cm3 at 80 ^\circ C was then developed (measured at 1.5 MHz and
+25 mT). This result represents an improvement of a factor 4 compared to the
+state of art Ni-Zn ferrites.",1103.5021v1
+2011-03-31,Anisotropic Inflation with Non-Abelian Gauge Kinetic Function,"We study an anisotropic inflation model with a gauge kinetic function for a
+non-abelian gauge field. We find that, in contrast to abelian models, the
+anisotropy can be either a prolate or an oblate type, which could lead to a
+different prediction from abelian models for the statistical anisotropy in the
+power spectrum of cosmological fluctuations. During a reheating phase, we find
+chaotic behaviour of the non-abelian gauge field which is caused by the
+nonlinear self-coupling of the gauge field. We compute a Lyapunov exponent of
+the chaos which turns out to be uncorrelated with the anisotropy.",1103.6164v2
+2011-04-07,Electron g-Factor Anisotropy in Symmetric (110)-oriented GaAs Quantum Wells,"We demonstrate by spin quantum beat spectroscopy that in undoped symmetric
+(110)-oriented GaAs/AlGaAs single quantum wells even a symmetric spatial
+envelope wavefunction gives rise to an asymmetric in-plane electron
+Land\'e-g-factor. The anisotropy is neither a direct consequence of the
+asymmetric in-plane Dresselhaus splitting nor of the asymmetric Zeeman
+splitting of the hole bands but is a pure higher order effect that exists as
+well for diamond type lattices. The measurements for various well widths are
+very well described within 14 x 14 band k.p theory and illustrate that the
+electron spin is an excellent meter variable to map out the internal -otherwise
+hidden- symmetries in two dimensional systems. Fourth order perturbation theory
+yields an analytical expression for the strength of the g-factor anisotropy,
+providing a qualitative understanding of the observed effects.",1104.1360v1
+2011-04-11,The effects of strong temperature anisotropy on the kinetic structure of collisionless slow shocks and reconnection exhausts. Part II: Theory,"Simulations of collisionless oblique propagating slow shocks have revealed
+the existence of a transition associated with a critical temperature anisotropy
+epsilon=1-mu_0(P_parallel-P_perpendicular)/ B^2 = 0.25 (Liu, Drake and Swisdak
+(2011)). An explanation for this phenomenon is proposed here based on
+anisotropic fluid theory, in particular the Anisotropic Derivative
+Nonlinear-Schrodinger-Burgers equation, with an intuitive model of the energy
+closure for the downstream counter-streaming ions. The anisotropy value of 0.25
+is significant because it is closely related to the degeneracy point of the
+slow and intermediate modes, and corresponds to the lower bound of the coplanar
+to non-coplanar transition that occurs inside a compound slow shock
+(SS)/rotational discontinuity (RD) wave. This work implies that it is a pair of
+compound SS/RD waves that bound the outflows in magnetic reconnection, instead
+of a pair of switch-off slow shocks as in Petschek's model. This fact might
+explain the rareness of in-situ observations of
+Petschek-reconnection-associated switch-off slow shocks.",1104.2055v1
+2011-04-17,On the theory of microwave absorption by the spin-1/2 Heisenberg-Ising magnet,"We analyze the problem of microwave absorption by the Heisenberg-Ising magnet
+in terms of shifted moments of the imaginary part of the dynamical
+susceptibility. When both, the Zeeman field and the wave vector of the incident
+microwave, are parallel to the anisotropy axis, the first four moments
+determine the shift of the resonance frequency and the line width in a
+situation where the frequency is varied for fixed Zeeman field. For the
+one-dimensional model we can calculate the moments exactly. This provides exact
+data for the resonance shift and the line width at arbitrary temperatures and
+magnetic fields. In current ESR experiments the Zeeman field is varied for
+fixed frequency. We show how in this situation the moments give perturbative
+results for the resonance shift and for the integrated intensity at small
+anisotropy as well as an explicit formula connecting the line width with the
+anisotropy parameter in the high-temperature limit.",1104.3298v1
+2011-05-25,Anisotropy of zero-resistance states in InN films under an in-plane magnetic filed,"We report low temperature current-voltage measurements on n-type InN films
+grown by molecular beam epitaxy. The zero-resistance state with a large
+critical current around 1 mA has been observed at 0.3 K. Under in-plane field
+configuration, the zero-resistance state shows a large anisotropy in critical
+current for B parallel and perpendicular to applied current. The ratio of
+critical current between B parallel and perpendicular to the applied current
+can be up to 2.5, when B = 0.15T. The anisotropy is explained by the vortex
+flow in the context of type II superconductivity. We have thus established an
+important aspect of the phenomenology of superconductivity in an otherwise
+typical narrow gap semiconductor.",1105.5150v1
+2011-05-31,g-Factor anisotropy of hole quantum wires induced by the Rashba interaction,"We present calculations of the g factors for the lower conductance steps of
+3D hole quantum wires. Our results prove that the anisotropy with magnetic
+field orientation, relative to the wire, originates in the Rashba spin-orbit
+coupling. We also analyze the relevance of the deformation, as the wire evolves
+from 3D towards a flat 2D geometry. For high enough wire deformations, the
+perpendicular g factors are greatly quenched by the Rashba interaction. On the
+contrary, parallel g factors are rather insensistive to the Rashba interaction,
+resulting in a high g factor anisotropy. For low deformations we find a more
+irregular behavior which hints at a sample dependent scenario.",1105.6278v2
+2011-06-05,Thermal-assisted Anisotropy and Thermal-driven Instability in the Superfluidity state of Two-Species Polar Fermi Gas,"We study the superfluid state of two-species heteronuclear Fermi gases with
+isotropic contact and anisotropic long-range dipolar interactions. By
+explicitly taking account of Fock exchange contribution, we derive
+self-consistent equations describing the pairing states in the system.
+Exploiting the symmetry of the system, we developed an efficient way of solving
+the self-consistent equations by exploiting the symmetries. We find that the
+temperature tends to increase the anisotropy of the pairing state, which is
+rather counterintuitive. We study the anisotropic properties of the system by
+examining the angular dependence of the number density distribution, the
+excitation spectrum and the pair correlation function. The competing effects of
+the contact interaction and the dipolar interaction upon the anisotropy are
+revealed. We derive and compute the superfluid mass density $\rho_{ij}$ for the
+system. Astonishingly, we find that $\rho_{zz}$ becomes negative above some
+certain temperature $T^*$($T<T_c$), signaling some instability of the system.
+This suggests that the elusive FFLO state may be observed in experiments, due
+to an anisotropic state with a spontaneously generated superflow.",1106.0891v1
+2011-06-06,Quantum Spin Hall Insulators with Interactions and Lattice Anisotropy,"We investigate the interplay between spin-orbit coupling and
+electron-electron interactions on the honeycomb lattice combining the cellular
+dynamical mean-field theory and its real space extension with analytical
+approaches. We provide a thorough analysis of the phase diagram and temperature
+effects at weak spin-orbit coupling. We systematically discuss the stability of
+the quantum spin Hall phase toward interactions and lattice anisotropy
+resulting in the plaquette-honeycomb model. We also show the evolution of the
+helical edge states characteristic of quantum spin Hall insulators as a
+function of Hubbard interaction and anisotropy. At very weak spin-orbit
+coupling and intermediate electron-electron interactions, we substantiate the
+existence of a quantum spin liquid phase.",1106.0943v2
+2011-06-08,"In-plane electronic anisotropy of underdoped ""122"" Fe-arsenide superconductors revealed by measurements of detwinned single crystals","The parent phases of the Fe-arsenide superconductors harbor an
+antiferromagnetic ground state. Significantly, the N\'eel transition is either
+preceded or accompanied by a structural transition that breaks the four fold
+symmetry of the high-temperature lattice. Borrowing language from the field of
+soft condensed matter physics, this broken discrete rotational symmetry is
+widely referred to as an Ising nematic phase transition. Understanding the
+origin of this effect is a key component of a complete theoretical description
+of the occurrence of superconductivity in this family of compounds, motivating
+both theoretical and experimental investigation of the nematic transition and
+the associated in-plane anisotropy. Here we review recent experimental progress
+in determining the intrinsic in-plane electronic anisotropy as revealed by
+resistivity, reflectivity and ARPES measurements of detwinned single crystals
+of underdoped Fe arsenide superconductors in the ""122"" family of compounds.",1106.1675v1
+2011-06-22,Tunable Magnonic Frequency and Damping in [Co/Pd]8 Multilayers with Variable Co Layer Thickness,"We report the experimental observation of collective picosecond magnetization
+dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The
+precession frequency shows large and systematic variation from about 5 GHz to
+about 90 GHz with the decrease in the Co layer thickness from 1.0 nm to 0.22 nm
+due to the linear increase in the perpendicular magnetic anisotropy. The
+damping coefficient 'alpha' is found to be inversely proportional to the Co
+layer thickness and a linear relation between the perpendicular magnetic
+anisotropy and 'alpha' is established. We discuss the possible reasons behind
+the enhanced damping as the d-d hybridization at the interface and spin
+pumping. These observations are significant for the applications of these
+materials in spintronics and magnonic crystals.",1106.4491v1
+2011-06-23,Direct measurements of anisotropic energy transfers in a rotating turbulence experiment,"We investigate experimentally the influence of a background rotation on the
+energy transfers in decaying grid turbulence. The anisotropic energy flux
+density, ${\bf F} ({\bf r}) = < \delta {\bf u}\,(\delta {\bf u})^2 >$, where
+$\delta {\bf u}$ is the vector velocity increment over separation ${\bf r}$, is
+determined for the first time using Particle Image Velocimetry. We show that
+rotation induces an anisotropy of the energy flux $\nabla \cdot {\bf F}$, which
+leads to an anisotropy growth of the energy distribution $E({\bf r}) = <
+(\delta {\bf u})^2 >$, in agreement with the K\'arm\'an-Howarth-Monin equation.
+Surprisingly, our results prove that this anisotropy growth is essentially
+driven by a nearly radial, but orientation-dependent, energy flux density ${\bf
+F} ({\bf r})$.",1106.4683v1
+2011-06-29,Non-Gaussianities in the Cosmological Perturbation Spectrum due to Primordial Anisotropy,"We investigate possible signatures of a pre-inflationary anisotropic phase in
+two-point and three-point correlation functions of the curvature perturbation
+for high-momentum modes which exit the horizon after isotropization. In this
+momentum regime, the early time dynamics admits a WKB description and the late
+time dynamics can be described in terms of a non-Bunch Davies vacuum state
+which encodes the information of initial anisotropy in the background
+spacetime. We compute the bi-spectrum for curvature perturbation in a canonical
+single-field action with and without higher derivative operators. We show that
+the bi-spectrum at late times, in either case, is enhanced for a flattened
+triangle configuration as well as a squeezed triangle configuration and compute
+the corresponding $f_{NL}$ parameters. The angular dependence and the
+particular momentum dependence of the $f_{NL}$ parameter appear as distinctive
+features of background anisotropy at early times.",1106.5840v3
+2011-07-07,Measurement of elliptic and higher order flow from ATLAS experiment at the LHC,"We present a differential measurement of the azimuthal anisotropy of charged
+hadron production in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}$=2.76 TeV.
+This azimuthal anisotropy is expanded into a Fourier series in azimuthal angle,
+where the coefficient for each term, $v_n$, characterizes the magnitude of the
+anisotropy at a particular angular scale. We extract $v_2-v_6$ via a discrete
+Fourier analysis of the two-particle $\Delta\phi-\Delta\eta$ correlation with a
+large $\Delta\eta$ gap ($|\Delta\eta|>2$), and via an event plane method based
+on the Forward Calorimeter. Significant $v_2-v_6$ values are observed over a
+broad range in $\pT$, $\eta$ and centrality, and they are found to be
+consistent between the two methods in the transverse momentum region $\pT<3-4$
+GeV. This suggests that the measured $v_2-v_6$ obtained from two-particle
+correlations at low $\pT$ with a large $\Delta\eta$ gap are consistent with the
+collective response of the system to the initial state geometry fluctuations,
+and is not the result of jet fragmentation or resonance decay.",1107.1468v2
+2011-08-04,Qualitative difference between the angular anisotropy parameters in fast electron scattering and photoionization,"It is demonstrated for the first time that in spite of well known big
+similarities between atomic ionization by photons and fast electrons, a
+qualitative difference exists in angular anisotropy parameters of electrons
+knocked out in these processes. The difference is disclosed here and attributed
+to distinction between normal (transverse) and virtual (longitudinal) photons.
+Formulas are derived for dipole and non-dipole angular anisotropy parameters in
+fast electronatom scattering. The ratio of quadrupole-to-dipole matrix elements
+is determined by the parameter \omega R/v << 1 where \omega is the transferred
+in collision energy, R is the ionized shell radius and v is the speed of
+projectile. This factor can be much bigger than in the case of photoionization,
+where one has the speed of light c that is much bigger than v . We illustrate
+general formulas by concrete results for outer s-subshells of noble gas atoms
+Ar and Xe. Even for very small transferred momentum q, in the so-called optical
+limit, the deviation from photoionization case is prominent and instructive.",1108.1013v1
+2011-08-10,Magnetic-field-induced nonlocal effects on the vortex interactions in twin-free YBa2Cu3O7,"The vortex lattice (VL) in the high-kappa superconductor YBa2Cu3O7, at 2 K
+and with the magnetic field parallel to the crystal c-axis, undergoes a
+sequence of transitions between different structures as a function of applied
+magnetic field. However, from structural studies alone, it is not possible to
+determine precisely the system anisotropy that governs the transitions between
+different structures. To address this question, here we report new small-angle
+neutron scattering measurements of both the VL structure at higher
+temperatures, and the field- and temperature-dependence of the VL form factor.
+Our measurements demonstrate how the influence of anisotropy on the VL, which
+in theory can be parameterized as nonlocal corrections, becomes progressively
+important with increasing magnetic field, and suppressed by increasing the
+temperature towards Tc. The data indicate that nonlocality due to different
+anisotropies play important roles in determining the VL properties.",1108.2176v1
+2011-08-31,Optical Conductivity Anisotropy in the Undoped Three-Orbital Hubbard Model for the Pnictides,"The resistivity anisotropy unveiled in the study of detwinned single crystals
+of the undoped 122 pnictides is here studied using the two-dimensional
+three-orbital Hubbard model in the mean-field approximation. Calculating the
+Drude weight in the x and y directions at zero temperature for a Q=(\pi,0)
+magnetically ordered state, the conductance along the antiferromagnetic
+direction is shown to be larger than along the ferromagnetic direction. This
+effect is caused by the suppression of the d_{yz} orbital at the Fermi surface,
+but additional insight based on the momentum dependence of the transitions
+induced by the current operator is provided. It is shown that the effective
+suppression of the inter-orbital hopping d_{xy} and d_{yz} along the y
+direction is the main cause of the anisotropy.",1109.0012v1
+2011-09-12,Single-ion anisotropy in Haldane chains and form factor of the O(3) nonlinear sigma model,"We consider spin-1 Haldane chains with single-ion anisotropy, which exists in
+known Haldane chain materials. We develop a perturbation theory in terms of
+anisotropy, where magnon-magnon interaction is important even in the low
+temperature limit. The exact two-particle form factor in the O(3) nonlinear
+sigma model leads to quantitative predictions on several dynamical properties
+including dynamical structure factor and electron spin resonance frequency
+shift. These agree very well with numerical results, and with experimental data
+on the Haldane chain material Ni(C$_5$H$_{14}$N$_2$)$_2$N$_3$(PF$_6$).",1109.2607v2
+2011-09-13,CMB Anomalies from Imperfect Dark Energy: Confrontation with the Data,"We test anisotropic dark energy models with the 7-year WMAP temperature
+observations data. In the presence of imperfect sources, due to large-scale
+gradients or anisotropies in the dark energy field, the CMB sky will be
+distorted anisotropically on its way to us by the ISW effect. The signal
+covariance matrix then becomes nondiagonal for small multipoles, but at $\ell
+\gtrsim 20$ the anisotropy is negligible. We parametrize possible violations of
+rotational invariance in the late universe by the magnitude of a
+post-Friedmannian deviation from isotropy and its scale dependence. This allows
+to obtain hints on possible imperfect nature of dark energy and the large-angle
+anomalous features in the CMB. A robust statistical analysis, subjected to
+various tests and consistency checks, is performed to compare the predicted
+correlations with those obtained from the satellite-measured CMB full sky maps.
+The preferred axis point towards $(l,b) = (168^\circ, -31^\circ)$ and the
+amplitude of the anisotropy is $\varpi_0 = (0.51\pm 0.94)$ (1$\sigma$ deviation
+quoted). The best-fit model has a steep blue anisotropic spectrum
+($n_{\mathrm{de}} = 3.1\pm1.5$).",1109.2778v1
+2011-09-14,Rise of azimuthal anisotropies as a signature of the Quark-Gluon-Plasma in relativistic heavy-ion collisions,"The azimuthal anisotropies of the collective transverse flow of hadrons are
+investigated in a large range of heavy-ion collision energy within the
+Parton-Hadron-String Dynamics (PHSD) microscopic transport approach which
+incorporates explicit partonic degrees of freedom in terms of strongly
+interacting quasiparticles (quarks and gluons) in line with an
+equation-of-state from lattice QCD as well as dynamical hadronization and
+hadronic dynamics in the final reaction phase. The experimentally observed
+increase of the elliptic flow $v_2$ with bombarding energy is successfully
+described in terms of the PHSD approach in contrast to a variety of other
+kinetic models based on hadronic interactions. The analysis of higher-order
+harmonics $v_3$ and $v_4$ shows a similar tendency of growing deviations
+between partonic and purely hadronic models with increasing bombarding energy.
+This signals that the excitation functions of azimuthal anisotropies provide a
+sensitive probe for the underling degrees of freedom excited in heavy-ion
+collisions.",1109.3039v2
+2011-09-26,Symmetric and antisymmetric exchange anisotropies in quasi-one-dimensional CuSe$_2$O$_5$ as revealed by ESR,"We present an electron spin resonance (ESR) study of single-crystalline spin
+chain-system CuSe$_2$O$_5$ in the frequency range between 9 GHz and 450 GHz. In
+a wide temperature range above the N\'{e}el temperature $T_N=17$ K we observe
+strong and anisotropic frequency dependence of a resonance linewidth. Although
+sizeable interchain interaction $J_{IC}\approx 0.1 J$ ($J$ is the intrachain
+interaction) is present in this system, the ESR results agree well with the
+Oshikawa-Affleck theory for one-dimensional $S=1/2$ Heisenberg antiferromagnet.
+This theory is used to extract the anisotropies present in CuSe$_2$O$_5$. We
+find that the symmetric anisotropic exchange $J_c=(0.04 \pm 0.01) \:J$ and the
+antisymmetric Dzyaloshinskii-Moriya (DM) interaction $D=(0.05\pm 0.01)\:J$ are
+very similar in size in this system. Staggered-field susceptibility induced by
+the presence of the DM interaction is witnessed in the macroscopic
+susceptibility anisotropy.",1109.5597v2
+2011-09-29,Anisotropic modules over artinian principal ideal rings,"Let V be a finite-dimensional vector space over a field k and let W be a
+1-dimensional k-vector space. Let < , >: V x V \to W be a symmetric bilinear
+form. Then < , > is called anisotropic if for all nonzero v \in V we have <v,v>
+\neq 0. Motivated by a problem in algebraic number theory, we come up with a
+generalization of the concept of anisotropy to symmetric bilinear forms on
+finitely generated modules over artinian principal ideal rings. We will give
+many equivalent definitions of this concept of anisotropy. One of the
+definitions shows that one can check if a form is anisotropic by checking if
+certain forms on vector spaces are anisotropic. We will also discuss the
+concept of quasi-anisotropy of a symmetric bilinear form, which has no useful
+vector space analogue. Finally we will discuss the radical root of a symmetric
+bilinear form, which doesn't have a useful vector space analogue either. All
+three concepts have applications in algebraic number theory.",1109.6483v1
+2011-09-30,Anisotropy and the integral closure,"Let K be a number field and let A be an order in K. The trace map from K to Q
+induces a non-degenerate symmetric bilinear form <,>: B x B \to Q/Z where B is
+a certain finite abelian group of size \Delta(A). In this article we discuss
+how one can obtain information about \mathcal{O}_K by purely looking at this
+symmetric bilinear form. The concepts of anisotropy and quasi-anisotropy, as
+defined in another article by the author, turn out to be very useful. We will
+for example show that under certain assumptions one can obtain \mathcal{O}_K
+directly from <,>.
+  In this article we will work in a more general setting than we have discussed
+above. We consider orders over Dedekind domains.",1109.6733v1
+2011-10-13,Incorporating Kinetic Physics into a Two-Fluid Solar-Wind Model with Temperature Anisotropy and Low-Frequency Alfven-Wave Turbulence,"We develop a 1D solar-wind model that includes separate energy equations for
+the electrons and protons, proton temperature anisotropy, collisional and
+collisionless heat flux, and an analytical treatment of low-frequency,
+reflection-driven, Alfven-wave turbulence. To partition the turbulent heating
+between electron heating, parallel proton heating, and perpendicular proton
+heating, we employ results from the theories of linear wave damping and
+nonlinear stochastic heating. We account for mirror and oblique firehose
+instabilities by increasing the proton pitch-angle scattering rate when the
+proton temperature anisotropy exceeds the threshold for either instability. We
+numerically integrate the equations of the model forward in time until a steady
+state is reached, focusing on two fast-solar-wind-like solutions. These
+solutions are consistent with a number of observations, supporting the idea
+that Alfven-wave turbulence plays an important role in the origin of the solar
+wind.",1110.3029v2
+2011-10-13,Anisotropy in BaFe2Se3 single crystals with double chains of FeSe tetrahedra,"We studied the anisotropy in physical properties of Ba1.00(4)Fe1.9(1)Se3.1(1)
+single crystals. BaFe2Se3 is a semiconductor below 300 K. Magnetization
+measurements show that there is a crossover from short-range antiferromagnetic
+(AFM) correlations at room temperature to a long-range AFM order with TN = 255
+K. The anisotropy of magnetization is consistent with the previous neutron
+results. This crossover is supported by the heat-capacity measurement, where
+the phase-transition peak is absent at 255 K. The superconducting transition at
+about 10 K is likely due to the small amount of beta-FeSe impurities.",1110.3039v3
+2011-10-18,Polarization properties of excitonic qu-bits in single self-assembled quantum dots,"We investigate polarization properties of neutral exciton emission in single
+self-assembled InAs/GaAs quantum dots. The in-plane shape and strain anisotropy
+strongly couple the heavy and light hole states and lead to large optical
+anisotropy with non-orthogonal linearly polarized states misaligned with
+respect to the crystallographic axes. Owing to a waveguiding experimental
+configuration, luminescence polarization along the growth axis has been
+observed revealing the presence of shear components of the deformation tensor
+out of the growth plane. Resonant luminescence experiments allowed determining
+the oscillator strength ratio of the two exciton eigenstates. Valence band
+mixing governs this ratio and can be very different from dot to dot, however
+the polarization anisotropy axis is quite fixed inside a scanned area of one
+\mum^{2} and indicates that the in-plane deformation direction to which it is
+related has a correlation length of the order of magnitude of one \mum^{2}.",1110.4042v1
+2011-10-19,Small scale anisotropy in turbulent shearless mixing,"The generation of small-scale anisotropy in turbulent shearless mixing is
+numerically investigated. Data from direct numerical simulations at Taylor
+Reynolds' numbers between 45 and 150 show that there is not only a significant
+departure of the longitudinal velocity derivative moments from the values found
+in homogeneous and isotropic turbulence, but that the variation of skewness has
+an opposite sign for the components across the mixing layer and parallel to it.
+The anisotropy induced by the presence of a kinetic energy gradient has a very
+different pattern from the one generated by an homogeneous shear. The
+transversal derivative moments in the mixing are in fact found to be very
+small, which highlights that smallness of the transversal moments is not a
+sufficient condition for isotropy.",1110.4328v1
+2011-10-24,"Magnetoresistance of 2D and 3D Electron Gas in LaAlO3/SrTiO3 Heterostructures: Influence of Magnetic Ordering, Interface Scattering and Dimensionality","Magnetoresistance (MR) anisotropy in LaAlO3/SrTiO3 (LAO/STO) interfaces is
+compared between samples prepared in high oxygen partial pressure (PO2) of 10-4
+mbar exhibiting quasi-two-dimensional (quasi-2D) electron gas and low PO2 of
+10-6 mbar exhibiting 3D conductivity. While MR of an order of magnitude larger
+was observed in low PO2 samples compared to those of high PO2 samples, large MR
+anisotropies were observed in both cases. The MR with the out-of-plane field is
+always larger compared to the MR with in-plane field suggesting lower
+dissipation of electrons from interface versus defect scattering. The quasi-2D
+interfaces show a negative MR at low temperatures while the 3D interfaces show
+positive MR for all temperatures. Furthermore, the angle relationship of MR
+anisotropy for these two different cases and temperature dependence of in-plane
+MR are also presented. Our study demonstrates that MR can be used to
+distinguish the dimensionality of the charge transport and various (defect,
+magnetic center, and interface boundary) scattering processes in this system.",1110.5290v1
+2011-10-24,Anisotropy of upper critical fields and thermally-activated flux flow of quenched KxFe2-ySe2 single crystals,"We report the anisotropy of the upper critical fields mu0Hc2(T) and
+thermally-activated flux flow (TAFF) behavior of quenched KxFe2-ySe2. Even
+though the post-annealing and quenching process enhances the superconducting
+volume fraction, it has a minor effect on the upper critical fields for H//c
+and H//ab. Analysis of the angular-dependence of resistivity rho_ab(theta,H)
+indicates that it follows the scaling law based on the anisotropic
+Ginzburg-Landau (GL) theory and the anisotropy Gamma(T) increases with
+decreasing temperature with Gamma(T) ~ 3.6 at 27 K. The resistivity of quenched
+sample exhibits an Arrhenius TAFF behavior for both field directions. Field
+dependence of thermally activated energy U0(H) implies that the collective flux
+creep is dominant in high fields and point defects are the main pinning source
+in this regime.",1110.5316v1
+2011-11-03,Effect of tensile stress on the in-plane resistivity anisotropy in BaFe2As2,"The effect of uniaxial tensile stress and the resultant strain on the
+structural/magnetic transition in the parent compound of the iron arsenide
+superconductor, BaFe$_2$As$_2$, is characterized by temperature-dependent
+electrical resistivity, x-ray diffraction and quantitative polarized light
+imaging. We show that strain induces a measurable uniaxial structural
+distortion above the first-order magnetic transition and significantly smears
+the structural transition. This response is different from that found in
+another parent compound, SrFe$_2$As$_2$, where the coupled structural and
+magnetic transitions are strongly first order. This difference in the
+structural responses explains the in-plain resistivity anisotropy above the
+transition in BaFe$_2$As$_2$. This conclusion is supported by the
+Ginzburg-Landau - type phenomenological model for the effect of the uniaxial
+strain on the resistivity anisotropy.",1111.0997v1
+2011-11-07,Observation of anisotropic diffusion of light in compacted granular porous materials,"It is known that compaction of granular matter can lead to anisotropic
+mechanical properties. Recent work has confirmed the link to pore space
+anisotropy, but the relation between compression, mechanical properties and
+material microstructure remains poorly understood and new diagnostic tools are
+needed. By studying the temporal and spatial characteristics of short optical
+pulses diffusively transmitted through compacted granular materials, we show
+that powder compaction can also give rise to strongly anisotropic diffusion of
+light. Investigating technologically important materials such as
+microcrystalline cellulose, lactose and calcium phosphate, we report increasing
+optical anisotropy with compaction force and radial diffusion constants being
+up to 1.7 times the longitudinal. This open new and attractive routes to
+material characterization and investigation of compression-induced structural
+anisotropy. In addition, by revealing inadequacy of isotropic diffusion models,
+our observations also have important implications for quantitative spectroscopy
+of powder compacts (e.g., pharmaceutical tablets).",1111.1700v2
+2011-12-05,Orbital upper critical field and its anisotropy of clean one- and two-band superconductors,"The Helfand-Werthamer (HW) scheme\cite{HW} of evaluating the orbital upper
+critical field is generalized to anisotropic superconductors in general, and to
+two-band clean materials, in particular. Our formal procedure differs from
+those in the literature; it reproduces not only the isotropic HW limit, but
+also the results of calculations for the two-band superconducting
+MgB$_2$\cite{MMK,DS} along with the existing data on $H_{c2}(T)$ and its
+anisotropy $\gamma(T)=H_{c2,ab}(T)/H_{c2,c}(T)$ ($a,c$ are the principal
+directions of a uniaxial crystal). Using rotational ellipsoids as model Fermi
+surfaces we apply the formalism developed to study $\gamma(T)$ for a few
+different anisotropies of the Fermi surface and of the order parameters. We
+find that even for a single band d-wave order parameter $\gamma(T)$ decreases
+on warming, however, relatively weakly. For order parameters of the form $
+\Delta(k_z) = \Delta_0(1+\eta\cos k_za)$,\cite{Xu} according to our simulations
+$\gamma(T)$ may either increase or decrease on warming even for a single band
+depending on the sign of $\eta$. Hence, the common belief that the multi-band
+Fermi surface is responsible for the temperature variation of $\gamma$ is
+proven incorrect.",1112.0996v2
+2011-12-06,Analyzing flow anisotropies with excursion sets in relativistic heavy-ion collisions,"We show that flow anisotropies in relativistic heavy-ion collisions can be
+analyzed using a certain technique of shape analysis of excursion sets recently
+proposed by us for CMBR fluctuations to investigate anisotropic expansion
+history of the universe. The technique analyzes shapes (sizes) of patches above
+(below) certain threshold value for transverse energy/particle number (the
+excursion sets) as a function of the azimuthal angle and rapidity. Modeling
+flow by imparting extra anisotropic momentum to the momentum distribution of
+particles from HIJING, we compare the resulting distributions for excursion
+sets at two different azimuthal angles. Angles with maximum difference in the
+two distributions identify the event plane, and the magnitude of difference in
+the two distributions relates to the magnitude of momentum anisotropy, i.e.
+elliptic flow.",1112.1177v1
+2011-12-08,Effect of the anisotropy on the glory structure of molecule-molecule scattering cross sections,"Total (elastic + rotationally inelastic) integral cross sections are computed
+for O$_2(^3\Sigma_g^-)$-O$_2(^3\Sigma_g^-)$ using a recent ab initio potential
+energy surface. The sampled velocity range allows us a thorough comparison of
+the glory interference pattern observed in molecular beam experiments. The
+computed cross sections are about 10% smaller than the measured ones, however,
+a remarkable agreement in the velocity positions of the glory extrema is
+achieved. By comparing with models where the anisotropy of the interaction is
+reduced or removed, it is found that the glory pattern is very sensitive to the
+anisotropy, especially the positions of the glory extrema.",1112.1925v1
+2011-12-16,Cosmic ray anisotropy studies with the Stockholm Educational Air Shower array,"The Stockholm Educational Air Shower Array (SEASA) project has established a
+network of GPS time-synchronised scintillator detector stations at high-schools
+in the Stockholm region. The primary aim of this project is outreach. A part of
+the network comprises a dense cluster of detector stations located at AlbaNova
+University Centre. This cluster is being used to study the cosmic ray
+anisotropy around the knee. Each station consists of three scintillator
+detectors in a triangular geometry which allows multiple timing measurements as
+the shower front sweeps over the station. The timing resolution of the system
+has been determined and the angular resolution has been studied using Monte
+Carlo simulations and is compared to data. The potential of this system to
+study small and large scale cosmic ray anisotropies is discussed.",1112.3902v1
+2011-12-29,Ordering of anisotropic polarizable polymer chains on the full many-body level,"We study the effect of dielectric anisotropy of polymers on their equilibrium
+ordering within mean-field theory but with a formalism that takes into account
+the full n-body nature of van der Waals forces. Dielectric anisotropy within
+polymers is to be expected as the electronic properties of the polymer will
+typically be different along the polymer than across its cross section. It is
+therefore physically intuitive that larger charge fluctuations can be induced
+along the chain than perpendicular to it. We show that this dielectric
+anisotropy leads to n-body interactions which can induce an isotropic--nematic
+transition. The two body and three body components of the full van der Waals
+interaction are extracted and it is shown how the two body term behaves like
+the phenomenological self-aligning-pairwise nematic interaction. At the three
+body interaction level we see that the nematic phase that is energetically
+favorable is discotic, however on the full n-body interaction level we find
+that the normal axial nematic phase is always the stable ordered phase. The
+n-body nature of our approach also shows that the key parameter driving the
+nematic-isotropic transition is the bare persistence length of the polymer
+chain.",1112.6278v1
+2011-12-29,Anisotropic Ginzburg-Landau and Lawrence-Doniach Models for Layered Ultracold Fermi Gases,"We study the anisotropic Ginzburg-Landau and Lawrence-Doniach models
+describing a layered superfluid ultracold Fermi gas in optical lattices. We
+derive the coefficients of the anisotropic Ginzburg-Landau and the mass tensor
+as a function of anisotropy, filling and interaction, showing that near the
+unitary limit the effective anisotropy of the masses is significantly reduced.
+The anisotropy parameter is shown to vary in realistic setups in a wide range
+of values. We also derive the Lawrence-Doniach model - often used to describe
+the 2D-3D dimensional crossover in layered superconductors - for a layered
+ultracold Fermi gas, obtaining a relation between the interlayer Josephson
+couplings and the Ginzburg-Landau masses. Comparing to the Ginzburg-Landau
+description, we find that the region of validity of the Lawrence-Doniach model
+is near the unitary limit.",1112.6429v2
+2012-01-07,Anisotropic Fast-Marching on cartesian grids using Lattice Basis Reduction,"We introduce a modification of the Fast Marching Algorithm, which solves the
+generalized eikonal equation associated to an arbitrary continuous riemannian
+metric, on a two or three dimensional domain. The algorithm has a logarithmic
+complexity in the maximum anisotropy ratio of the riemannian metric, which
+allows to handle extreme anisotropies for a reduced numerical cost. We prove
+the consistence of the algorithm, and illustrate its efficiency by numerical
+experiments. The algorithm relies on the computation at each grid point of a
+special system of coordinates: a reduced basis of the cartesian grid, with
+respect to the symmetric positive definite matrix encoding the desired
+anisotropy at this point.",1201.1546v3
+2011-11-11,Observations of Large Scale Sidereal Anisotropy in 1 and 11 TeV cosmic rays from the MINOS experiment,"The MINOS Near and Far Detectors are two large, functionally-identical,
+steel-scintillating sampling calorimeters located at depths of 220 mwe and 2100
+mwe respectively. The detectors observe the muon component of hadronic showers
+produced from cosmic ray interactions with nuclei in the earth's atmosphere.
+From the arrival direction of these muons, the anisotropy in arrival direction
+of the cosmic ray primaries can be determined. The MINOS Near and Far Detector
+have observed anisotropy on the order of 0.1% at 1 and 11 TeV respectively. The
+amplitude and phase of the first harmonic at 1 TeV are
+8.2$\pm$1.7(stat.)$\times 10^{-4}$ and (8.9$\pm$12.1(stat.))$^{\circ}$, and at
+11 TeV are 3.8$\pm$0.5(stat.)$\times 10^{-4}$ and
+(27.2$\pm$7.2(stat.))$^{\circ}$.",1201.2621v1
+2012-01-16,Testing Yukawa-like potentials from f(R)-gravity in elliptical galaxies,"We present the first analysis of extended stellar kinematics of elliptical
+galaxies where a Yukawa--like correction to the Newtonian gravitational
+potential derived from f(R)-gravity is considered as an alternative to dark
+matter. In this framework, we model long-slit data and planetary nebulae data
+out to 7 Re of three galaxies with either decreasing or flat dispersion
+profiles. We use the corrected Newtonian potential in a dispersion-kurtosis
+Jeans analysis to account for the mass-anisotropy degeneracy. We find that
+these modified potentials are able to fit nicely all three elliptical galaxies
+and the anisotropy distribution is consistent with that estimated if a dark
+halo is considered. The parameter which measures the ""strength"" of the
+Yukawa-like correction is, on average, smaller than the one found previously in
+spiral galaxies and correlates both with the scale length of the Yukawa-like
+term and the orbital anisotropy.",1201.3363v1
+2012-01-31,Phase-space consistency of stellar dynamical models determined by separable augmented densities,"Assuming the separable augmented density, it is always possible to construct
+a distribution function of a spherical population with any given density and
+anisotropy. We consider under what conditions the distribution constructed as
+such is in fact non-negative everywhere in the accessible phase-space. We first
+generalize known necessary conditions on the augmented density using fractional
+calculus. The condition on the radius part R(r^2) (whose logarithmic derivative
+is the anisotropy parameter) is equivalent to the complete monotonicity of
+R(1/w)/w. The condition on the potential part on the other hand is given by its
+derivative up to any order not greater than (3/2-beta) being non-negative where
+beta is the central anisotropy parameter. We also derive a specialized
+inversion formula for the distribution from the separable augmented density,
+which leads to sufficient conditions on separable augmented densities for the
+non-negativity of the distribution. The last generalizes the similar condition
+derived earlier for the generalized Cuddeford system to arbitrary separable
+systems.",1202.0004v1
+2012-02-20,Sign-reversal of the in-plane resistivity anisotropy in hole-doped iron pnictides,"The in-plane anisotropy of the electrical resistivity across the coupled
+orthorhombic and magnetic transitions of the iron pnictides has been
+extensively studied in the parent and electron-doped compounds. All these
+studies universally show that the resistivity $\rho_{a}$ across the long
+orthorhombic axis $a_{O}$ - along which the spins couple antiferromagnetically
+below the magnetic transition temperature - is smaller than the resistivity
+$\rho_{b}$ of the short orthorhombic axis $b_{O}$, i. e. $\rho_{a}<\rho_{b}$.
+Here we report that in the hole-doped compounds
+Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$, as the doping level increases, the
+resistivity anisotropy initially becomes vanishingly small, and eventually
+changes sign for sufficiently large doping, i. e. $\rho_{b}<\rho_{a}$. This
+observation is in agreement with a recent theoretical prediction that considers
+the anisotropic scattering of electrons by spin-fluctuations in the
+orthorhombic/nematic state.",1202.4430v2
+2012-02-21,Refining the Spin Hamiltonian in the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$ using Single Crystals,"We report thermodynamic measurements of the S=1/2 kagome lattice
+antiferromagnet ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$, a promising candidate system with
+a spin-liquid ground state. Using single crystal samples, the magnetic
+susceptibility both perpendicular and parallel to the kagome plane has been
+measured. A small, temperature-dependent anisotropy has been observed, where
+$\chi_{z}/ \chi_{p} > 1$ at high temperatures and $\chi_{z}/ \chi_{p} < 1$ at
+low temperatures. Fits of the high-temperature data to a Curie-Weiss model also
+reveal an anisotropy. By comparing with theoretical calculations, the presence
+of a small easy-axis exchange anisotropy can be deduced as the primary
+perturbation to the dominant Heisenberg nearest neighbor interaction. These
+results have great bearing on the interpretation of theoretical calculations
+based on the kagome Heisenberg antiferromagnet model to the experiments on
+ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$.",1202.4729v2
+2012-03-02,A common solution to the cosmic ray anisotropy and gradient problems,"Multichannel Cosmic Ray (CR) spectra and the large scale CR anisotropy can
+hardly be made compatible in the framework of conventional isotropic and
+homogeneous propagation models. These models also have problems explaining the
+longitude distribution and the radial emissivity gradient of the $\gamma$-ray
+galactic interstellar emission. We argue here that accounting for a well
+physically motivated correlation between the CR escape time and the spatially
+dependent magnetic turbulence power can naturally solve both problems. Indeed,
+by exploiting this correlation we find propagation models that fit a wide set
+of CR primary and secondary spectra, and consistently reproduce the CR
+anisotropy in the energy range $10^2 - 10^4 \GeV$ and the $\gamma$-ray
+longitude distribution recently measured by Fermi-LAT.",1203.0570v2
+2012-03-05,In-plane and Out-of-plane Plasma Resonances in Optimally Doped La1.84Sr0.16CuO4,"We addressed the inconsistency between the electron mass anisotropy ratios
+determined by the far-infrared experiments and DC conductivity measurements. By
+eliminating possible sources of error and increasing the sensitivity and
+resolution in the far-infrared reflectivity measurement on the single
+crystalline and on the polycrystalline La1.84Sr0.16CuO4, we have unambiguously
+identified that the source of the mass anisotropy problem is in the estimation
+of the free electron density involved in the charge transport and
+superconductivity. In this study we found that only 2.8 % of the total
+doping-induced charge density is itinerant at optimal doping. Our result not
+only resolves the mass anisotropy puzzle but also points to a novel electronic
+structure formed by the rest of the electrons that sets the stage for the high
+temperature superconductivity.",1203.0963v1
+2012-03-08,An Effective Medium Approach to Electron Waves: Graphene Superlattices,"We develop an effective medium approach to characterize the propagation of
+matter waves in periodic structures, such as graphene or semiconductor
+superlattices. It is proven that the time evolution of the states that are not
+more localized in space than the characteristic period of the structure can be
+described exactly through an effective Hamiltonian, and that the electronic
+band structure of the system can be exactly determined from the effective
+Hamiltonian. As an illustration of the application of the method, we
+characterize the mesoscopic response of graphene superlattices. It is shown
+that these structures may be described using simply two effective parameters: a
+dispersive potential, and an anisotropy tensor that characterizes the
+pseudospin. Our model predicts that a graphene superlattice characterized by an
+indefinite anisotropy tensor - such that the eigenvalues of the tensor have
+opposite signs - may permit the perfect tunneling of all the stationary states
+with a specific value of the energy when it is paired with a dual graphene
+superlattice with positive definite anisotropy tensor.",1203.1902v2
+2012-03-15,A study of the anisotropy associated with dipole asymmetry in heavy ion collisions,"The anisotropy associated with the initial dipole asymmetry in heavy ion
+collisions is studied via the two-particle relative azimuthal azimuthal angle
+(\Delta\phi=\phi^a-\phi^b) correlations, within a multi-phase transport model.
+For a broad selection of centrality, transverse momenta (pT^{a,b}) and
+pseudorapidity (\eta^{a,b}), a fitting method is used to decompose the
+anisotropy into a rapidity-even component, characterized by the Fourier
+coefficient v1, and a global momentum conservation component. The extracted v1
+values are negative for pT<=0.7-0.9 GeV, reach a maximum at 2-3 GeV, and
+decreases at higher pT. The v1 values vary weakly with \eta and centrality, but
+increases with collision energy and parton cross-section. The extracted global
+momentum conservation component is found to depend on \Delta\eta= \eta^a-\eta^b
+for \Delta\eta<3.",1203.3410v3
+2012-03-16,Scaling patterns for azimuthal anisotropy in Pb+Pb collisions at Root_s = 2.76 TeV: Further constraints on transport coefficients,"Azimuthal anisotropy measurements for charged hadrons, characterized by the
+second order Fourier coefficient $v_2$, are used to investigate the path length
+($L$) and transverse momentum ($p_T$) dependent jet quenching patterns of the
+QCD medium produced in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$\,TeV. $v_2$
+shows a linear decrease as $1/\sqrt{p_T}$ and a linear increase with the medium
+path length difference ($\Delta L$) in- and out of the $\Psi_2$ event plane.
+These patterns compliment a prior observation of the scaling of jet quenching
+($R_{\rm AA}$) measurements. Together, they suggest that radiative parton
+energy loss is a dominant mechanism for jet suppression, and $v_2$ stems from
+the difference in the parton propagation length $\Delta L$.An estimate of the
+transport coefficient $\hat{q}$, gives a value comparable to that obtained in a
+prior study of the scaling properties of $R_{\rm AA}$. These results suggest
+that high-$p_T$ azimuthal anisotropy measurements provide strong constraints
+for delineating the mechanism(s) for parton energy loss, as well as for
+reliable extraction of $\hat{q}$.",1203.3605v1
+2012-03-16,Shapes and Probabilities of Galaxy Clusters II: Comparisons with observations,"We identify low redshift clusters and groups in the Sloan Digital Sky Survey
+(SDSS) and estimate their kinetic and correlation potential energies. We
+compare the distribution of these energies to the predictions by Yang and
+Saslaw (2012) and in the process estimate a measure of an average 3-dimensional
+velocity and spatial anisotropy of a sample of clusters. We find that the
+inferred velocity anisotropy is correlated with the inferred spatial
+anisotropy. We also find that the general shape of the energy distribution
+agrees with theory over a wide range of scales from small groups to
+superclusters once the uncertainties and fluctuations in the estimated energies
+are included.",1203.3823v2
+2012-04-05,Dynamical magnetic anisotropy and quantum phase transitions in a vibrating spin-1 molecular junction,"We study the electronic transport through a spin-1 molecule in which
+mechanical stretching produces a magnetic anisotropy. In this type of device, a
+vibron mode along the stretching axis will couple naturally to the molecular
+spin. We consider a single molecular vibrational mode and find that the
+electron-vibron interaction induces an effective correction to the magnetic
+anisotropy that shifts the ground state of the device toward a non-Fermi liquid
+phase. A transition into a Fermi liquid phase could then be achieved, by means
+of mechanical stretching, passing through an underscreened spin-1 Kondo regime.
+We present numerical renormalization group results for the differential
+conductance, the spectral density, and the magnetic susceptibility across the
+transition.",1204.1108v2
+2012-04-23,Broken degeneracies: the rotation curve and velocity anisotropy of the Milky Way halo,"We use distant Blue Horizontal Branch stars with Galactocentric distances 16
+< r/kpc < 48 as kinematic tracers of the Milky Way dark halo. We model the
+tracer density as an oblate, power-law embedded within a spherical power-law
+potential. Using a distribution function method, we estimate the overall
+power-law potential and the velocity anisotropy of the halo tracers. We measure
+the slope of the potential to be gamma ~ 0.4 and the overall mass within 50 kpc
+is ~ 4 x 10^11 M_sol. The tracer velocity anisotropy is radially biased with
+beta ~ 0.5, which is in good agreement with local solar neighbourhood studies.
+Our results provide an accurate outer circular velocity profile for the Milky
+Way and suggest a relatively high concentration dark matter halo (c_vir ~ 20).",1204.5189v2
+2012-04-25,Susceptibility anisotropy in an iron arsenide superconductor revealed by x-ray diffraction in pulsed magnetic fields,"In addition to unconventional high-Tc superconductivity, the iron arsenides
+exhibit strong magnetoelastic coupling and a notable electronic anisotropy
+within the a-b plane. We relate these properties by studying underdoped
+Ba(Fe{1-x}Co{x})2As2 by x-ray diffraction in pulsed magnetic fields up to 27.5
+Tesla. We exploit magnetic detwinning effects to demonstrate anisotropy in the
+in-plane susceptibility, which develops at the structural phase transition
+despite the absence of magnetic order. The degree of detwinning increases
+smoothly with decreasing temperature, and a single- domain condition is
+realized over a range of field and temperature. At low temperatures we observe
+an activated behavior, with a large hysteretic remnant effect. Detwinning was
+not observed within the superconducting phase for accessible magnetic fields.",1204.5693v1
+2012-05-07,Random field and random anisotropy O(N) spin systems with a free surface,"We study the surface scaling behavior of a semi-infinite $d$-dimensional O(N)
+spin system in the presence of quenched random field and random anisotropy
+disorders. It is known that above the lower critical dimension
+$d_{\mathrm{lc}}=4$ the infinite models undergo a paramagnetic-ferromagnetic
+transition for $N>N_c$ ($N_c=2.835$ for random field and $N_c=9.441$ for random
+anisotropy). For $N<N_c$ and $d<d_{\mathrm{lc}}$ there exists a
+quasi-long-range ordered phase with zero order parameter and a power-law decay
+of spin correlations. Using functional renormalization group we derive the
+surface scaling laws which describe the ordinary surface transition for
+$d>d_{\mathrm{lc}}$ and the long-range behavior of spin correlations near the
+surface in the quasi-long-range ordered phase for $d<d_{\mathrm{lc}}$. The
+corresponding surface exponents are calculated to one-loop order. The obtained
+results can be applied to the surface scaling of periodic elastic systems in
+disordered media and amorphous magnets.",1205.1338v1
+2012-05-21,Unilateral interactions in granular packings: A model for the anisotropy modulus,"Unilateral interparticle interactions have an effect on the elastic response
+of granular materials due to the opening and closing of contacts during
+quasi-static shear deformations. A simplified model is presented, for which
+constitutive relations can be derived. For biaxial deformations the elastic
+behavior in this model involves three independent elastic moduli: bulk, shear,
+and anisotropy modulus. The bulk and the shear modulus, when scaled by the
+contact density, are independent of the deformation. However, the magnitude of
+the anisotropy modulus is proportional to the ratio between shear and
+volumetric strain. Sufficiently far from the jamming transition, when
+corrections due to non-affine motion become weak, the theoretical predictions
+are qualitatively in agreement with simulation results.",1205.4593v1
+2012-06-04,Anisotropy of spin relaxation and transverse transport in metals,"Using first principles methods we explore the anisotropy of the spin
+relaxation and transverse transport properties in bulk metals with respect to
+the direction of the spin quantization axis in paramagnets or of the
+spontaneous magnetization in ferromagnets. Owing to the presence of the
+spin-orbit interaction the orbital and spin character of the Bloch states
+depends sensitively on the orientation of the spins relative to the crystal
+axes. This leads to drastic changes in quantities which rely on interband
+mixing induced by the spin-orbit interaction. The anisotropy is particularly
+striking for quantities which exhibit spiky and irregular distribution in the
+Brillouin zone, such as the spin-mixing parameter or the Berry curvature of the
+electronic states. We demonstrate this for three cases: (i) the Elliott-Yafet
+spin-relaxation mechanism in paramagnets with structural inversion symmetry;
+(ii) the intrinsic anomalous Hall effect in ferromagnets; and (iii) the spin
+Hall effect in paramagnets. We discuss the consequences of the pronounced
+anisotropic behavior displayed by these properties for spin-polarized transport
+applications.",1206.0589v1
+2012-06-28,Giant birefringence in optical antenna arrays with widely tailorable optical anisotropy,"The manipulation of light by conventional optical components such as a
+lenses, prisms and wave plates involves engineering of the wavefront as it
+propagates through an optically-thick medium. A new class of ultra-flat optical
+components with high functionality can be designed by introducing abrupt phase
+shifts into the optical path, utilizing the resonant response of arrays of
+scatters with deeply-subwavelength thickness. As an application of this
+concept, we report a theoretical and experimental study of birefringent arrays
+of two-dimensional (V- and Y-shaped) optical antennas which support two
+orthogonal charge-oscillation modes and serve as broadband, anisotropic optical
+elements that can be used to locally tailor the amplitude, phase, and
+polarization of light. The degree of optical anisotropy can be designed by
+controlling the interference between the light scattered by the antenna modes;
+in particular, we observe a striking effect in which the anisotropy disappears
+as a result of destructive interference. These properties are captured by a
+simple, physical model in which the antenna modes are treated as independent,
+orthogonally-oriented harmonic oscillators.",1206.6792v1
+2012-07-06,Two-band superconductivity featuring different anisotropies in the ternary iron silicide Lu$_{2}$Fe$_{3}$Si$_{5}$,"We report detailed studies of the upper critical field and low-temperature
+specific heat in the two-gap superconductor Lu$_{2}$Fe$_{3}$Si$_{5}$. The
+anisotropy of the upper critical field suggests that the active band is
+quasi-one-dimensional. Low-temperature specific heat in magnetic fields reveals
+that the virtual $H_{c2}$ in the passive band is almost isotropic. These
+results strongly indicate that the two bands have two different anisotropies,
+similar to the typical two-gap superconductor MgB$_{2}$, and their interplay
+may be essential to the two-gap superconductivity in Lu$_{2}$Fe$_{3}$Si$_{5}$.",1207.1502v1
+2012-07-17,Multicomponent Skyrmion lattices and their excitations,"We study quantum Hall ferromagnets with a finite density topologically
+charged spin textures in the presence of internal degrees of freedom such as
+spin, valley, or layer indices, so that the system is parametrised by a
+$d$-component complex spinor field. In the absence of anisotropies, we find
+formation of a hexagonal Skyrmion lattice which completely breaks the
+underlying SU(d) symmetry. The ground state charge density modulation, which
+inevitably exists in these lattices, vanishes exponentially in $d$. We compute
+analytically the complete low-lying excitation spectrum, which separates into
+$d^{2}-1$ gapless acoustic magnetic modes and a magnetophonon. We discuss the
+role of effective mass anisotropy for SU(3)-valley Skyrmions relevant for
+experiments with AlAs quantum wells. Here, we find a transition, which breaks a
+six-fold rotational symmetry of a triangular lattice, followed by a formation
+of a square lattice at large values of anisotropy strength.",1207.4021v1
+2012-07-27,Evidence for a cos(4\varphi) Modulation of the Superconducting Energy Gap of Optimally Doped FeTe_{0.6}Se_{0.4} Single Crystals Using Laser Angle-Resolved Photoemission Spectroscopy,"We study the superconducting(SC)-gap anisotropy of the \Gamma-centered hole
+Fermi surface in optimally doped FeTe_{0.6}Se_{0.4} (T_c = 14.5 K), using
+laser-excited angle-resolved photoemission spectroscopy (ARPES). We observe
+sharp superconducting coherence peaks at T = 2.5 K. In contrast to earlier
+ARPES studies but consistent with thermodynamic results, the momentum
+dependence shows a \cos(4\varphi) modulation of the SC-gap anisotropy. The
+observed SC-gap anisotropy strongly indicates that the pairing interaction is
+not a conventional phonon-mediated isotropic one. Instead, the results suggest
+the importance of second-nearest-neighbor electronic interactions between the
+iron sites in the framework of s_\pm-wave superconductivity.",1207.6571v3
+2012-08-13,Quarkonium dissociation by anisotropy,"We compute the screening length for quarkonium mesons moving through an
+anisotropic, strongly coupled N=4 super Yang-Mills plasma by means of its
+gravity dual. We present the results for arbitrary velocities and orientations
+of the mesons, as well as for arbitrary values of the anisotropy. The
+anisotropic screening length can be larger or smaller than the isotropic one,
+and this depends on whether the comparison is made at equal temperatures or at
+equal entropy densities. For generic motion we find that: (i) mesons dissociate
+above a certain critical value of the anisotropy, even at zero temperature;
+(ii) there is a limiting velocity for mesons in the plasma, even at zero
+temperature; (iii) in the ultra-relativistic limit the screening length scales
+as $(1-v^2)^\epsilon$ with \epsilon =1/2, in contrast with the isotropic result
+\epsilon =1/4.",1208.2672v2
+2012-08-17,Interface induced perpendicular magnetic anisotropy in Co/CoO/Co thin film structure: An in-situ MOKE investigation,"Co /CoO/Co polycrystalline film was grown on Si (001) substrate and magnetic
+properties have been investigated using in-situ magneto-optic Kerr effect
+during growth of the sample. Magnetic anisotropy with easy axis perpendicular
+to the film surface has been observed in top Co layer, whereas bottom layer was
+found to be soft with in-plane magnetization without any influence of top
+layer. Ex-situ in-plane and out-of-plane diffraction measurements revealed that
+the growth of Co on oxidized interface takes place with preferential
+orientation of c-axis perpendicular to the film plane, which results in the
+observed perpendicular magnetic anisotropy. Texturing of the c-axis is expected
+to be a result of minimization of the interface energy due to hybridization
+between Co and oxygen at the interface.",1208.3673v1
+2012-09-06,Giant Anisotropy of Spin-Orbit Splitting at the Bismuth Surface,"We investigate the bismuth (111) surface by means of time and angle resolved
+photoelectron spectroscopy. The parallel detection of the surface states below
+and above the Fermi level reveals a giant anisotropy of the Spin-Orbit (SO)
+spitting. These strong deviations from the Rashba-like coupling cannot be
+treated in $\textbf{k}\cdot \textbf{p}$ perturbation theory. Instead, first
+principle calculations could accurately reproduce the experimental dispersion
+of the electronic states. Our analysis shows that the giant anisotropy of the
+SO splitting is due to a large out-of plane buckling of the spin and orbital
+texture.",1209.1219v2
+2012-09-10,Strong anisotropy in two-dimensional surfaces with generic scale invariance: Gaussian and related models,"Among systems that display generic scale invariance, those whose asymptotic
+properties are anisotropic in space (strong anisotropy, SA) have received a
+relatively smaller attention, specially in the context of kinetic roughening
+for two-dimensional surfaces. This is in contrast with their experimental
+ubiquity, e.g. in the context of thin film production by diverse techniques.
+Based on exact results for integrable (linear) cases, here we formulate a SA
+Ansatz that, albeit equivalent to existing ones borrowed from equilibrium
+critical phenomena, is more naturally adapted to the type of observables that
+are measured in experiments on the dynamics of thin films, such as one and
+two-dimensional height structure factors. We test our Ansatz on a paradigmatic
+nonlinear stochastic equation displaying strong anisotropy like the Hwa-Kardar
+equation [Phys. Rev. Lett. 62, 1813 (1989)], that was initially proposed to
+describe the interface dynamics of running sand piles. A very important role to
+elucidate its SA properties is played by an accurate (Gaussian) approximation
+through a non-local linear equation that shares the same asymptotic properties.",1209.1968v3
+2012-09-11,Topological defects and misfit strain in magnetic stripe domains of lateral multilayers with perpendicular magnetic anisotropy,"Stripe domains are studied in perpendicular magnetic anisotropy films
+nanostructured with a periodic thickness modulation that induces the lateral
+modulation of both stripe periods and inplane magnetization. The resulting
+system is the 2D equivalent of a strained superlattice with properties
+controlled by interfacial misfit strain within the magnetic stripe structure
+and shape anisotropy. This allows us to observe, experimentally for the first
+time, the continuous structural transformation of a grain boundary in this 2D
+magnetic crystal in the whole angular range. The magnetization reversal process
+can be tailored through the effect of misfit strain due to the coupling between
+disclinations in the magnetic stripe pattern and domain walls in the in-plane
+magnetization configuration.",1209.2281v1
+2012-09-20,Interface Induced Anisotropy and nematic glass/gel state in Jammed Aqueous Laponite Suspensions,"Aqueous suspensions of Laponite, a system composed of disk-like
+nanoparticles, are found to develop optical birefringence over several days,
+well after the suspensions solidified due to jamming. The optical anisotropy is
+particularly enhanced near the air Laponite suspension interface over
+length-scales of several millimetres, which is beyond five orders of magnitude
+larger than the particle length scale, suggestive of large scale ordering
+influenced by the interface. The orientational order increases with time and is
+always greater for higher concentration of salt, higher concentration of
+Laponite and higher temperature of the suspension. While weakly birefringent,
+Laponite suspensions covered by paraffin oil do not show any enhancement in the
+optical anisotropy near the interface compared to that in the bulk. We suggest
+that the expedited structure formation near the air interface propagating
+progressively inside the sample is responsible for the observed behaviour. We
+discuss the observed nematic ordering in the context of glasslike and gellike
+microstructure associated with aqueous Laponite suspensions.",1209.4507v1
+2012-09-22,Origin of perpendicular magneto-crystalline anisotropy in L10-FeNi under tetragonal distortion,"We investigated the origin of perpendicular magneto-crystalline anisotropy
+(MCA) in L10 ordered FeNi alloy using first-principles density-functional
+calculations. We found that the perpendicular MCA of L10-FeNi arises
+predominantly from the constituent Fe atoms, which is consistent with recent
+measurements of the anisotropy of the Fe orbital magnetic moment of L10-FeNi by
+x-ray magnetic circular dichroism. Analysis of the second-order perturbation of
+the spin-orbit interaction indicates that spin-flip excitations between the
+occupied majority-spin and unoccupied minority-spin bands make a considerable
+contribution to the perpendicular MCA as does the spin-conservation term in the
+minority-spin bands. Furthermore, the MCA energy increases as the in-plane
+lattice parameter decreases (increasing the axial ratio c/a). The increase in
+the MCA energy can be attributed to further enhancement of the spin-flip term
+due to modulation of the Fe d(xy) and d(x2-y2) orbital components around the
+Fermi level under the compressive in-plane distortion.",1209.5003v2
+2012-10-01,The distinct in-plane resistivity anisotropy in the nematic states of detwinned NaFeAs and FeTe single crystals: evidences for Hund's rule metal,"The in-plane resistivity anisotropy has been studied with the Montgomery
+method on two detwinned parent compounds of the iron-based superconductors,
+NaFeAs and FeTe. For NaFeAs, the resistivity in the antiferromagnetic (AFM)
+direction is smaller than that in the ferromagnetic (FM) direction, similar to
+that observed in BaFe2As2 before. While for FeTe, the resistivity in the AFM
+direction is larger than that in the FM direction. We show that these two
+opposite resistivity anisotropy behaviors could be attributed to the strong
+Hund's rule coupling effects: while the iron pnictides are in the itinerant
+regime, where the Hund's rule coupling causes strong reconstruction and
+nematicity of the electronic structure; the FeTe is in the localized regime,
+where Hund's rule coupling makes hopping along the FM direction easier than
+along the AFMdirection, similar to the colossal magnetoresistance observed in
+some manganites.",1210.0397v1
+2012-10-03,Magnetic anisotropy energy of disordered tetragonal Fe-Co systems from ab initio alloy theory,"We present results of systematic fully relativistic first-principles
+calculations of the uniaxial magnetic anisotropy energy (MAE) of a disordered
+and partially ordered tetragonal Fe-Co alloy using the coherent potential
+approximation (CPA). This alloy has recently become a promising system for thin
+ferromagnetic films with a perpendicular magnetic anisotropy. We find that
+existing theoretical approaches to homogeneous random bulk Fe-Co alloys, based
+on a simple virtual crystal approximation (VCA), overestimate the maximum MAE
+values obtained in the CPA by a factor of four. This pronounced difference is
+ascribed to the strong disorder in the minority spin channel of real alloys,
+which is neglected in the VCA and which leads to a broadening of the d-like
+eigenstates at the Fermi energy and to the reduction of the MAE. The ordered
+Fe-Co alloys with a maximum L1_0-like atomic long-range order can exhibit high
+values of the MAE, which, however, get dramatically reduced by small
+perturbations of the perfect order.",1210.1028v2
+2012-10-15,Ground state properties and excitation spectrum of a two dimensional gas of bosonic dipoles,"We present a quantum Monte Carlo study of two-dimensional dipolar Bose gases
+in the limit of zero temperature. The analysis is mainly focused on the
+anisotropy effects induced in the homogeneous gas when the polarization angle
+with respect to the plane is changed. We restrict our study to the regime where
+the dipolar interaction is strictly repulsive, although the strength of the
+pair repulsion depends on the vector interparticle distance. Our results show
+that the effect of the anisotropy in the energy per particle scales with the
+gas parameter at low densities as expected, and that this scaling is preserved
+for all polarization angles even at the largest densities considered here. We
+also evaluate the excitation spectrum of the dipolar Bose gas in the context of
+the Feynman approximation and compare the results obtained with the Bogoliubov
+ones. As expected, we find that these two approximations agree at very low
+densities, while they start to deviate from each other as the density
+increases. For the largest densities studied, we observe a significant
+influence of the anisotropy of the dipole-dipole interaction in the excitation
+spectrum.",1210.3969v1
+2012-10-22,Accelerating the switching of logical units by anisotropy driven magnetization dynamics,"In this work the magnetization dynamics of clusters supported on non-magnetic
+substrates is shown to exhibit an unprecedented complex response when subjected
+to external magnetic fields. The field-driven magnetization reversal of small
+Co clusters deposited on a Cu(111) surface has been studied by means of
+first-principles calculations and atomistic spin dynamics simulations. For
+applied fields ranging from 1 Tesla to 10 Tesla, we observe a coherent
+magnetization reversal with switching times in the range of several tenths of
+picoseconds to several nanoseconds, depending on the field strength. We find a
+non-monotonous dependence of the switching times with respect to the strength
+of the applied field, which we prove to have its origin in the complex magnetic
+anisotropy landscape of these low dimensional systems. This effect is shown to
+be stable for temperatures around 10 K, and is possible to realize over a range
+of exchange interactions and anisotropy landscapes. Possible experimental
+routes to achieve this unique switching behaviour are discussed.",1210.5836v1
+2012-10-22,Spin polarization anisotropy in a narrow spin-orbit-coupled nanowire quantum dot,"One and two-electron systems confined in a single and coupled quantum dots
+defined within a nanowire with a finite radius are studied in the context of
+spin-orbit coupling effects. Anisotropy of the spin-orbit interaction is
+discussed in terms of the system geometry and orientation of the external
+magnetic field vector. We find that there are easy and hard spin polarization
+axes and in the quantum dot with strong lateral confinement electron spin
+becomes well defined in spite of the presence of spin-orbit coupling. We
+present an analytical solution for the one-dimensional limit and study its
+validity for nanowires of finite radii by comparing the results with a full
+three-dimensional calculation. The results are also confronted with the recent
+measurements of the effective Lande factor and avoided crossing width
+anisotropy in InSb nanowire quantum dots [S. Nadj-Perge et al., Phys. Rev.
+Lett. 108, 166801 (2012)].",1210.5901v3
+2012-10-31,Probing Dark Energy Anisotropy,"Wide area cosmological surveys enable investigation of whether dark energy
+properties are the same in different directions on the sky. Cosmic microwave
+background observations strongly restrict any dynamical effects from
+anisotropy, in an integrated sense. For more local constraints we compute
+limits from simulated distance measurements for various distributions of survey
+fields in a Bianchi I anisotropic universe. We then consider the effects of
+fitting for line of sight properties where isotropic dynamics is assumed
+(testing the accuracy through simulations) and compare sensitivities of
+observational probes for anisotropies, from astrophysical systematics as well
+as dark energy. We also point out some interesting features of anisotropic
+expansion in Bianchi I cosmology.",1210.8221v2
+2012-11-06,Anisotropies and Homogeneities of Superconducting Properties in Iron-Platinum-Arsenide Ca10(Pt3As8)(Fe1.79Pt0.21As2)5,"We report a study on the anisotropy of superconducting properties in single
+crystalline Ca10(Pt4-{\delta}As8)(Fe1.79Pt0.21As2)5 with Tc ~13.6 K. Under a
+field of 5 Oe, the sample reaches fully-diamagnetic state at ~10 K for H//c,
+and ~8 K for H//ab, indicating the presence of slight inhomogeneities. The
+magnetization measurements reveal fish-tail effect in the hysteresis loop for
+both H//c and H//ab. Averaged critical current densities at low magnetic fields
+along the c-axis and ab-plane Jc(H//c) and Jc(H//ab) at 5 K are estimated to be
+0.9*10^5 and 0.7*10^5 A/cm2, respectively. Resistive transitions under magnetic
+field show broadening, which is consistent with a relatively large anisotropy
+of upper critical field. Magneto-optical images reveal homogenous current flow
+within the ab-plane.",1211.1221v2
+2012-11-27,The extended Lawrence-Doniach model: the temperature evolution of the in-plane magnetic field anisotropy,"Using the quasi-classical formalism we provide the description of the
+temperature and field-direction dependence of the in-plane upper critical field
+in layered superconductors, taking into account the interlayer Josephson
+coupling and the paramagnetic spin splitting. We generalize the
+Lawrence-Doniach model for the case of high magnetic fields and show that the
+re-entrant superconductivity is naturally described by our formalism when
+neglecting the Pauli pair breaking effect. We demonstrate that in layered
+superconductors the in-plane anisotropy of the onset of superconductivity
+exhibits four different\ temperature regimes: from the Ginzburg-Landau type in
+the vicinity of the critical temperature $T_{c0}$ with anisotropies of
+coherence lengths, up to the FFLO type induced by the strong interference
+between the modulation vector and the orbital effect. Our results are in
+agreement with the experimental measurements of the field-angle dependence of
+the superconducting onset temperature of the organic compound (TMTSF)$_{2}
+$ClO$_{4}$.",1211.6262v1
+2012-12-05,Event-by-event distributions of azimuthal asymmetries in ultrarelativistic heavy-ion collisions,"Relativistic dissipative fluid dynamics is a common tool to describe the
+space-time evolution of the strongly interacting matter created in
+ultrarelativistic heavy-ion collisions. For a proper comparison to experimental
+data, fluid-dynamical calculations have to be performed on an event-by-event
+basis. Therefore, fluid dynamics should be able to reproduce, not only the
+event-averaged momentum anisotropies, $<v_{n}>$, but also their distributions.
+In this paper, we investigate the event-by-event distributions of the
+initial-state and momentum anisotropies $\epsilon_n$ and $v_n$, and their
+correlations. We demonstrate that the event-by-event distributions of relative
+$v_n$ fluctuations are almost equal to the event-by-event distributions of
+corresponding $\epsilon_n$ fluctuations, allowing experimental determination of
+the relative anisotropy fluctuations of the initial state. Furthermore, the
+correlation $c(v_2,v_4)$ turns out to be sensitive to the viscosity of the
+fluid providing an additional constraint to the properties of the strongly
+interacting matter.",1212.1008v1
+2012-12-12,Dissociation of quarkonium in an anisotropic hot QCD medium,"We have investigated the properties of quarkonium states in an anisotropic
+hot QCD medium by correcting the full Cornell potential, not the Coulomb term
+alone as usually done in the literature, with a dielectric function from the
+hard-loop resummed gluon propagator. We have found that in-medium modification
+in anisotropic medium causes less screening than in isotropic medium. In the
+short distance limit, potential does not show any medium dependence whereas in
+the long-distance limit, it reduces to the Coulomb potential with a dynamically
+screened color charge. In addition, anisotropy in momentum space introduces a
+characteristic angular dependence in the potential and as a result, quarkonium
+states in anisotropic medium are more tightly bound than in isotropic medium.
+In particular, quark pairs aligned in the direction of anisotropy are more
+bound than perpendicular to the direction of anisotropy.",1212.2803v3
+2012-12-21,Critical properties of a spin-1 triangular lattice Ising antiferromagnet,"We employ Monte Carlo simulations in order to investigate critical behavior
+of a geometrically frustrated spin-1 Ising antiferromagnet on a triangular
+lattice in the presence of a single-ion anisotropy. It has been previously
+found that long-range order can exist in the isotropic system with a spin
+larger than some critical value estimated as 11/2. We show that the presence of
+the single-ion anisotropy can lead to a partial long-range order in the
+low-temperature region even below this critical value, namely for the spin 1,
+within a certain range of the anisotropy strength. At higher temperatures we
+identify another phase of the Berezinsky-Kosterlitz-Thouless type and using a
+finite-size scaling analysis evaluate the correlation decay exponent. We also
+study densities of various local spin patterns in the respective phases.",1212.5488v1
+2013-01-07,Curvature Perturbations in Anisotropic Inflation with Symmetry Breaking,"We study curvature perturbations in the anisotropic inflationary model with a
+complex scalar field charged under a $U(1)$ gauge field in Bianchi I universe.
+Due to Abelian Higgs mechanism, the gauge field receives an additional
+longitudinal mode. We verify that the dominant contributions into statistical
+anisotropies come from matter fields perturbations and one can neglect the
+contributions from the metric perturbations. It is shown that the contribution
+of longitudinal mode into the statistical anisotropy power spectrum, though
+exponentially small, has an opposite sign compared to the corresponding
+contribution from the transverse mode. We obtain an upper bound on gauge
+coupling in order to satisfy the observational constraints on curvature
+perturbations anisotropy.",1301.1219v3
+2013-01-17,Low field anisotropic colossal magnetoresistance in $Sm_{0.53} Sr_{0.47} Mn O_3$ thin films,"SSMO5347 thin films (thicknesses ~200 nm) were deposited by on-axis dc
+magnetron sputtering on the single crystal LSAT (001) substrates. These films
+are oriented along the out of plane c-direction. The ferromagnetic and
+insulator-metal transition occurs at 96 K and 91 K, respectively. The
+magnetization easy axis is observed to lie in the plane of the film while the
+magnetic hard axis is found to be along the normal to this. The
+magnetotransport of the SSMO films, which was measured as a function of angle
+(theta) between the magnetic field (H) and plane of the film, shows colossal
+anisotropy. Magnetoresistance (MR) decreases drastically as theta increases
+from 0 degree (H//easy axis) to 90 degree (H//hard axis). The out-of-plane
+anisotropic MR (AMR) is as high as 88 % at H=3.6 kOe and 78 K. The colossal
+anisotropy has been explained in terms of the magnetic anisotropies at play and
+the magnetic domain motion in applied magnetic field.",1301.4048v1
+2013-01-23,Comparative study of tight-binding and ab initio electronic structure calculations focused on magnetic anisotropy in ordered CoPt alloy,"An empirical multiorbital (spd) tight binding (TB) model including magnetism
+and spin-orbit coupling is applied to calculations of magnetic anisotropy
+energy (MAE) in CoPt L1_0 structure. A realistic Slater-Koster parametrisation
+for single-element transition metals is adapted for the ordered binary alloy.
+Spin magnetic moment and density of states are calculated using a
+full-potential linearized augmented plane-wave (LAPW) ab initio method and our
+TB code with different variants of the interatomic parameters. Detailed mutual
+comparison of this data allows for determination of a subset of the compound TB
+parameters tuning of which improves the agreement of the TB and LAPW results.
+MAE calculated as a function of band filling using the refined parameters is in
+broad agreement with ab initio data for all valence states and in quantitative
+agreement with ab initio and experimental data for the natural band filling.
+Our work provides a practical basis for further studies of relativistic
+magnetotransport anisotropies by means of local Green's function formalism
+which is directly compatible with our TB approach.",1301.5369v1
+2013-01-31,Effects of Transverse Magnetic Anisotropy on Current-Induced Spin Switching,"Spin-polarized transport through bistable magnetic adatoms or single-molecule
+magnets (SMMs), which exhibit both uniaxial and transverse magnetic anisotropy,
+is considered theoretically. The main focus is on the impact of transverse
+anisotropy on transport characteristics and the adatom's/SMM's spin. In
+particular, we analyze the role of quantum tunneling of magnetization (QTM) in
+the mechanism of the current-induced spin switching, and show that the QTM
+phenomenon becomes revealed as resonant peaks in the average values of the
+molecule's spin and in the charge current. These features appear at some
+resonant fields and are observable when at least one of the electrodes is
+ferromagnetic. We also show that the conductance generally depends on the
+relative orientation of the average adatom's/SMM's spin and electrode's
+magnetic moment. This spin-valve like magnetoresistance effect can be used to
+control spin switching of the adatom's/SMM's spin.",1302.1074v1
+2013-02-07,Ferromagnetic Exchange Anisotropy from Antiferromagnetic Superexchange in the Mixed 3d-5d Transition-Metal Compound Sr3CuIrO6,"We report a combined experimental and theoretical study of the unusual
+ferromagnetism in the one-dimensional copper-iridium oxide Sr$_3$CuIrO$_6$.
+Utilizing Ir $L_3$ edge resonant inelastic x-ray scattering, we reveal a large
+gap magnetic excitation spectrum. We find that it is caused by an unusual
+exchange anisotropy generating mechanism, namely, strong ferromagnetic
+anisotropy arising from antiferromagnetic superexchange, driven by the
+alternating strong and weak spin-orbit coupling on the $5d$ Ir and 3d Cu
+magnetic ions, respectively. From symmetry consideration, this novel mechanism
+is generally present in systems with edge-sharing Cu$^{2+}$O$_4$ plaquettes and
+Ir$^{4+}$O$_6$ octahedra. Our results point to unusual magnetic behavior to be
+expected in mixed 3d-5d transition-metal compounds via exchange pathways that
+are absent in pure 3d or 5d compounds.",1302.1818v2
+2013-02-12,Direction dependence of the power spectrum and its effect on the Cosmic Microwave Background Radiation,"We study several anisotropic inflationary models and their implications for
+the observed violation of statistical isotropy in the CMBR data. In two of
+these models the anisotropy decays very quickly during the inflationary phase
+of expansion. We explicitly show that these models lead to violation of
+isotropy only for low l CMBR modes. Our primary aim is to fit the observed
+alignment of l=2,3 multipoles to the theoretical models. We use two measures,
+based on the power tensor, which contains information about the alignment of
+each multipole, to quantify the anisotropy in data. One of the measures uses
+the dispersion in eigenvalues of the power tensor. We also define another
+measure which tests the overall correlation between two different multipoles.
+We perturbatively compute these measures of anisotropy and fix the theoretical
+parameters by making a best fit to l=2,3 multipoles. We show that some of the
+models studied are able to consistently explain the observed violation of
+statistical isotropy.",1302.2706v1
+2013-02-13,Local mechanical response in semiflexible polymer networks subjected to an axisymmetric prestress,"Analytical and numerical calculations are presented for the mechanical
+response of fiber networks in a state of axisymmetric prestress, in the limit
+where geometric non-linearities such as fiber rotation are negligible. This
+allows us to focus on the anisotropy deriving purely from the non-linear
+force-extension curves of individual fibers. The number of independent elastic
+coefficients for isotropic, axisymmetric and fully anisotropic networks are
+enumerated, before deriving expressions for the response to a locally applied
+force that can be tested against e.g. microrheology experiments. Localised
+forces can generate anisotropy away from the point of application, so numerical
+integration of non-linear continuum equations is employed to determine the
+stress field, and induced mechanical anisotropy, at points located directly
+behind and in front of a force monopole. Results are presented for the wormlike
+chain model in normalised forms, allowing them to be easily mapped to a range
+of systems. Finally, the relevance of these findings to naturally occurring
+systems and directions for future investigation are discussed.",1302.3049v2
+2013-02-15,A fingerprint of surface-tension anisotropy in the free-energy cost of nucleation,"We focus on the Gibbs free energy $\Delta G$ for nucleating a droplet of the
+stable phase (e.g. solid) inside the metastable parent phase (e.g. liquid),
+close to the first-order transition temperature. This quantity is central to
+the theory of homogeneous nucleation, since it superintends the nucleation
+rate. We recently introduced a field theory describing the dependence of
+$\Delta G$ on the droplet volume $V$, taking into account besides the
+microscopic fuzziness of the droplet-parent interface, also small fluctuations
+around the spherical shape whose effect, assuming isotropy, was found to be a
+characteristic logarithmic term. Here we extend this theory, introducing the
+effect of anisotropy in the surface tension, and show that in the limit of
+strong anisotropy $\Delta G(V)$ once more develops a term logarithmic on $V$,
+now with a prefactor of opposite sign with respect to the isotropic case. Based
+on this result, we argue that the geometrical shape that large solid nuclei
+mostly prefer could be inferred from the prefactor of the logarithmic term in
+the droplet free energy, as determined from the optimization of its
+near-coexistence profile.",1302.3712v1
+2013-02-16,Magnetic state of pyrochlore Cd2Os2O7 emerging from strong competition of ligand distortions and longer-range crystalline anisotropy,"By many-body quantum-chemical calculations, we investigate the role of two
+structural effects - local ligand distortions and the anisotropic Cd-ion
+coordination - on the magnetic state of Cd2Os2O7, a spin S=3/2 pyrochlore. We
+find that these effects strongly compete, rendering the magnetic interactions
+and ordering crucially depend on these geometrical features. Without trigonal
+distortions a large easy-plane magnetic anisotropy develops. Their presence,
+however, reverses the sign of the zero-field splitting and causes a large
+easy-axis anisotropy (D = -6.8 meV), which in conjunction with the
+antiferromagnetic exchange interaction (J = 6.4 meV) stabilizes an
+all-in/all-out magnetic order. The competition uncovered here is a generic
+feature of pyrochlore magnets.",1302.3989v1
+2013-02-20,Anisotropy of the Superconducting State in Sr2RuO4,"Despite intense studies the exact nature of the order parameter in
+superconducting Sr2RuO4 remains unresolved. We have used small-angle neutron
+scattering to study the vortex lattice in Sr2RuO4 with the field applied close
+to the basal plane, taking advantage of the transverse magnetization. We
+measured the intrinsic superconducting anisotropy between the c axis and the
+Ru-O basal plane (~60), which greatly exceeds the upper critical field
+anisotropy (~20). Our result imposes significant constraints on possible models
+of triplet pairing in Sr2RuO4 and raises questions concerning the direction of
+the zero spin projection axis.",1302.4810v3
+2013-02-20,The chromo-Weibel instability in an expanding background,"In this proceedings contribution we review recent calculations of the
+dynamics of the chromo-Weibel instability in the quark gluon plasma. This
+instability is present in gauge theories with a one-particle distribution
+function which is momentum-space anisotropic in the local rest frame. The
+conditions necessary for triggering this instability can be present already in
+the color-glass-condensate initial state or dynamically generated by the rapid
+longitudinal expansion of the matter created in a heavy-ion collision. Using
+the hard-loop framework we study the case that the one-particle distribution
+function possesses an arbitrary initial momentum anisotropy that increases in
+time due to longitudinal free streaming. The resulting three-dimensional
+dynamical equations for the chromofield evolution are solved numerically. We
+find that there is regeneration of the longitudinal pressure due to unstable
+plasma modes; nevertheless, the system seems to maintain a high-degree of
+momentum-space anisotropy. Despite this anisotropy, we find that there is rapid
+longitudinal thermalization of the plasma due to the non-linear mode couplings
+inherent in the unstable evolution.",1302.5098v1
+2013-02-22,Mixing of blackbodies: Increasing our view of inflation to 17 e-folds with spectral distortions from Silk damping,"Silk damping in the early Universe, before and during recombination, erases
+anisotropies in the cosmic microwave background (CMB) on small scales. This
+power, which disappears from anisotropies, appears in the monopole as y-type,
+i-type and \mu-type distortions. The observation of the CMB spectral
+distortions will thus make available to us the information about the primordial
+power spectrum on scales corresponding to the comoving wavenumbers $8< k < 10^4
+Mpc^{-1}$ increasing our total view of inflation, when combined with CMB
+anisotropies, to span 17 e-folds. These distortions can be understood simply as
+mixing of blackbodies of different temperatures and the subsequent
+comptonization of the resulting distortions.",1302.5633v1
+2013-02-28,Anisotropy in the cosmic radiation at TeV energy,"In recent years very important results were obtained from cosmic ray
+experiments about the arrival direction distribution of primaries in the TeV
+energy range. As most of these particles are charged nuclei, they are deflected
+by the magnetic field they pass through before reaching the Earth surface, the
+effect of the Lorentz force being inversely proportional to the particle
+energy. As far as the local interstellar medium is known, the gyroradius of a
+10 TeV proton is expected to be only 100 a.u., small enough to make the arrival
+direction distribution isotropic. Since 1930s a ""large scale""
+(90{\deg}-120{\deg}) anisotropy is known to exist, generally interpreted as the
+combined effect of sources far away and magnetic fields nearby. Nonetheless, in
+the last decade experiments like Tibet-ASg, Milagro, ARGO-YBJ and IceCube
+discovered structures as wide as 10{\deg}-30{\deg} all over the sky at ~ 10 TeV
+energy, what is unexplainable within the standard model of cosmic rays. In this
+paper a review of the most recent experimental results about cosmic ray
+anisotropy is given, together with the status of the art of theoretical efforts
+aimed at interpreting them within the current cosmic-ray paradigma.",1302.7184v1
+2013-03-05,Constraining the Anisotropic Expansion of Universe,"We study the possibly existing anisotropy in the accelerating expansion
+universe with the Union2 Type Ia supernovae data and Gamma-ray burst data. We
+construct a direction-dependent dark energy model and constrain the anisotropy
+direction and strength of modulation. We find that the maximum anisotropic
+deviation direction is $(l,\,b)=(126^{\circ},\,13^{\circ})$ (or equivalently
+$(l,\,b)=(306^{\circ},\,-13^{\circ})$), and the current anisotropy level is
+$g_0=0.030_{+0.010}^{-0.030}$ ($1\sigma$ confidence level with Union2 data).
+Our results do not show strong evidence for the anisotropic dark energy model.
+We also discuss potential methods that may distinguish the peculiar velocity
+field from the anisotropic dark energy model.",1303.0961v4
+2013-03-09,Dark Matter implications of Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background,"The detailed origin of the diffuse gamma-ray background is still unknown.
+However, the contribution of unresolved sources is expected to induce
+small-scale anisotropies in this emission, which may provide a way to identify
+and constrain the properties of its contributors. Recent studies have predicted
+the contributions to the angular power spectrum (APS) from extragalactic and
+galactic dark matter (DM) annihilation or decay. The Fermi-LAT collaboration
+reported detection of angular power with a significance larger than $3\sigma$
+in the energy range from 1 GeV to 10 GeV on 22 months of data [Ackermann et al.
+2012]. For these preliminary results the already published Fermi-LAT APS
+measurements [Ackermann et al. 2012] are compared to the accurate predictions
+for DM anisotropies from state-of-the-art cosmological simulations as presented
+in [Fornasa et al. 2013] to derive constraints on different DM candidates.",1303.2154v1
+2013-03-13,Electric control of a $\{Fe_4\}$ single-molecule magnet in a single-electron transistor,"Using first-principles methods we study theoretically the properties of an
+individual $\{Fe_4\}$ single-molecule magnet (SMM) attached to metallic leads
+in a single-electron transistor geometry. We show that the conductive leads do
+not affect the spin ordering and magnetic anisotropy of the neutral SMM. On the
+other hand, the leads have a strong effect on the anisotropy of the charged
+states of the molecule, which are probed in Coulomb blockade transport.
+Furthermore, we demonstrate that an external electric potential, modeling a
+gate electrode, can be used to manipulate the magnetic properties of the
+system. For a charged molecule, by localizing the extra charge with the gate
+voltage closer to the magnetic core, the anisotropy magnitude and spin ordering
+converges to the values found for the isolated $\{Fe_4\}$ SMM. We compare these
+findings with the results of recent quantum transport experiments in
+three-terminal devices.",1303.3283v1
+2013-03-21,Tuning magnetic anisotropy in (001) oriented L10 (Fe1-xCux)55Pt45 films,"We have achieved (001) oriented L10 (Fe1-xCux)55Pt45 thin films, with
+magnetic anisotropy up to 3.6x10^7 erg/cm^3, using atomic-scale multilayer
+sputtering and post annealing at 400 {\deg}C for 10 seconds. By fixing the Pt
+concentration, structure and magnetic properties are systematically tuned by
+the Cu addition. Increasing Cu content results in an increase in the tetragonal
+distortion of the L10 phase, significant changes to the film microstructure,
+and lowering of the saturation magnetization and anisotropy. The relatively
+convenient synthesis conditions, along with the tunable magnetic properties,
+make such materials highly desirable for future magnetic recording
+technologies.",1303.5208v1
+2013-03-21,Spin dynamics of two bosons in an optical lattice site: a role of anharmonicity and anisotropy of the trapping potential,"We study a spin dynamics of two magnetic Chromium atoms trapped in a single
+site of a deep optical lattice in a resonant magnetic field. Dipole-dipole
+interactions couple spin degrees of freedom of the two particles to their
+motion in the site. The motion is quantized, therefore a trap geometry combined
+with two-body contact s-wave interactions influence a spin dynamics through the
+energy spectrum of the two atom system. Anharmonicity and anisotropy of the
+site results in a `fine' structure of two body eigenenergies. The structure can
+be easily resolved by a weak magnetic dipole-dipole interactions. As an example
+we examine the effect of anharmonicity and anisotropy of the binding potential
+on the Einstein-de Haas effect. We show that the weak dipolar interactions
+provide a perfect tool for a precision spectroscopy of the energy spectrum of
+the interacting few particle system.",1303.5232v2
+2013-04-07,Thermodynamic properties of a diluted Heisenberg ferromagnet with interaction anisotropy -- magnetocaloric point of view,"The thermodynamics of a site-diluted ferromagnetic Heisenberg model for spin
+$S=1/2$ with interaction anisotropy in spin space is investigated. The study is
+aimed at presenting the magnetocaloric properties of such a model, including
+the entropy and temperature changes in magnetization/demagnetization processes,
+generalized Gr\""uneisen ratio as well as the quantities characterizing the
+efficiency of magnetic cooling cycles. The results are obtained using Pair
+Approximation (PA) method and extensively compared with the Molecular Field
+Approximation (MFA) calculations. The importance of interaction anisotropy and
+site-dilution is discussed. The inadequacy of the MFA approach (even on the
+qualitative level) is found for selected quantities, while PA provides the
+results which are consistent with the experimentally observed behaviour.",1304.2034v1
+2013-04-09,Anisotropies in the Gravitational Wave Background from Preheating,"We investigate the anisotropies in the gravitational wave (GW) background
+produced at preheating after inflation. Using lattice field theory simulations
+of a massless preheating model, we show that the GW amplitude depends
+sensitively on the value of the decay product field chi coupled to the inflaton
+phi, with the only requisite that chi is light during inflation. We find a
+strong anisotropy in the amplitude of the GW background on large angular
+scales, the details of which strongly depend on the reheating dynamics. We
+expect similar conclusions for a wide class of inflationary models with light
+scalar fields. If future direct detection GW experiments are capable of
+detecting the GW produced by preheating, they should also be able to detect
+this effect. This could eventually provide a powerful way to distinguish
+between different inflationary and preheating scenarios.",1304.2657v1
+2013-04-19,Anisotropic Heisenberg Model in Thin Film Geometry,"The effect of the anisotropy in the exchange interaction on the phase
+diagrams and magnetization behavior of the Heisenberg thin film has been
+investigated with effective field formulation in a two spin cluster using the
+decoupling approximation. Phase diagrams and magnetization behaviors have been
+obtained for several different cases, by grouping the systems in accordance
+with, whether the surfaces/interior of the film have anisotropic exchange
+interaction or not. Particular attention has been paid on the evolution of the
+special point coordinate with the anisotropy in the exchange interaction. It
+has been concluded that for increasing ratio of the anisotropies in the
+exchange interaction between the surface and interior of the film, special
+point disappears at a special value of this ratio.",1304.5552v1
+2013-04-21,Uniaxial pressure effect on structural and magnetic phase transitions in NaFeAs and its comparison with as-grown and annealed BaFe$_2$As$_2$,"We use neutron scattering to study the effect of uniaxial pressure on the
+tetragonal-to-orthorhombic structural ($T_s$) and
+paramagnetic-to-antiferromagnetic ($T_N$) phase transitions in NaFeAs and
+compare the outcome with similar measurements on as-grown and annealed
+BaFe$_2$As$_2$. In previous work on as-grown BaFe$_2$As$_2$, uniaxial pressure
+necessary to detwin the sample was found to induce a significant increase in
+zero pressure $T_N$ and $T_s$. However, we find that similar uniaxial pressure
+used to detwin NaFeAs and annealed BaFe$_2$As$_2$ has a very small effect on
+their $T_N$ and $T_s$.Since transport measurements on these samples still
+reveal resistivity anisotropy above $T_N$ and $T_s$, we conclude that such
+anisotropy cannot be due to uniaxial strain induced $T_N$ and $T_s$ shifts, but
+must arise from intrinsic electronic anisotropy in these materials.",1304.5794v1
+2013-04-23,Interfacial tuning of perpendicular magnetic anisotropy and spin magnetic moment in CoFe/Pd multilayers,"We report on a strong perpendicular magnetic anisotropy in [CoFe 0.4nm/Pd t]6
+(t = 1.0-2.0 nm) multilayers fabricated by DC sputtering in a ultrahigh vacuum
+chamber. Saturation magnetization, $M_s$, and uniaxial anisotropy, $K_u$, of
+the multilayers decrease with increasing the spacing thickness, with a $M_s$ of
+155 emu/cc and a $K_u$ of 1.14$\times 10^5$ J/m$^3$ at a spacing thickness of t
+= 2 nm. X-ray absorption spectroscopy and X-ray magnetic circular dichroism
+measurements reveal that spin and orbital magnetic moments of Co and Fe in CoFe
+film decrease as function of Pd thickness, indicating the major contribution of
+surface/interfacial magnetism to the magnetic properties of the film.",1304.6156v2
+2013-04-25,Exploring a New Class of Non-stationary Spatial Gaussian Random Fields with Varying Local Anisotropy,"Gaussian random fields (GRFs) constitute an important part of spatial
+modelling, but can be computationally infeasible for general covariance
+structures. An efficient approach is to specify GRFs via stochastic partial
+differential equations (SPDEs) and derive Gaussian Markov random field (GMRF)
+approximations of the solutions. We consider the construction of a class of
+non-stationary GRFs with varying local anisotropy, where the local anisotropy
+is introduced by allowing the coefficients in the SPDE to vary with position.
+This is done by using a form of diffusion equation driven by Gaussian white
+noise with a spatially varying diffusion matrix. This allows for the
+introduction of parameters that control the GRF by parametrizing the diffusion
+matrix. These parameters and the GRF may be considered to be part of a
+hierarchical model and the parameters estimated in a Bayesian framework. The
+results show that the use of an SPDE with non-constant coefficients is a
+promising way of creating non-stationary spatial GMRFs that allow for physical
+interpretability of the parameters, although there are several remaining
+challenges that would need to be solved before these models can be put to
+general practical use.",1304.6949v2
+2013-04-27,Rotation of Triangular Vortex Lattice in the Two-Band Superconductor MgB2,"To identify the contributions of the multiband nature and the anisotropy of a
+microscopic electronic structure to a macroscopic vortex lattice morphology, we
+develop a method based on the Eilenberger theory near Hc2 combined with the
+first-principles band calculation to estimate the stable vortex lattice
+configuration. For a typical two-band superconductor MgB2, successive
+transitions of vortex lattice orientation that have been observed recently by
+small angle neutron scattering [Das, et al.: Phys. Rev. Lett. 108 (2012)
+167001] are explained by the characteristic field-dependence of twoband
+superconductivity and the competition of sixfold anisotropy between the sigma-
+and pi-bands. The reentrant transition at low temperature reflects the Fermi
+velocity anisotropy of the sigma-band.",1304.7314v1
+2013-05-13,Anisotropy of Cosmic Acceleration,"In this paper, we study the anisotropy of cosmic acceleration by dividing the
+Union2 Type Ia supernova dataset into 12 subsets according to their positions
+in Galactic coordinate system. In each region, we derive the deceleration
+parameter $q_0$ as the diagnostic to quantify the anisotropy level in the
+corresponding direction, and construct $q_0$ anisotropic maps by combining
+these $q_0$ values. In addition to the monopole component, we find the
+significant dipole effect in the $q_0$-maps with the amplitude
+$A_1=0.466^{+0.255}_{-0.205}$, which deviates from zero at more than 2-$\sigma$
+level. The direction of the best-fit dipole is ($\theta=108.8^{\circ}$,
+$\phi=187.0^{\circ}$) in Galactic system. Interesting enough, we find the
+direction of this dipole is nearly perpendicular to the CMB kinematic dipole,
+and the angle between them is $95.7^{\circ}$. The perpendicular relation is
+anomalous at the 1-in-10 level.",1305.2701v2
+2013-05-15,Anisotropy of flow in stochastically generated porous media,"Models of porous media are often applied to relatively small systems, which
+leads not only to system-size-dependent results, but also to phenomena that
+would be absent in larger systems. Here we investigate one such finite-size
+effect: anisotropy of the permeability tensor. We show that a non-zero angle
+between the external body force and macroscopic flux vector exists in
+three-dimensional periodic models of sizes commonly used in computer
+simulations and propose a criterion, based on the system size to the grain size
+ratio, for this phenomenon to be relevant or negligible. The finite-size
+anisotropy of the porous matrix induces a pressure gradient perpendicular to
+the axis of a porous duct and we analyze how this effect scales with the system
+and grain sizes.",1305.3426v1
+2013-05-24,Two Photon Correlation in Anisotropic Quark-gluon plasma (aQGP),"The only way to obtain the space-time structure of heavy ion collision is
+through the study of two-particle momentum correlations. Thus we have studied
+the intensity correlation for the photons having fixed transverse momentum of
+one of the photons ($k_{1T}$= 2 GeV) in anisotropic Quark Gluon Plasma (aQGP)
+to have an idea about emission zone in presence of initial momentum anisotropy.
+The {\em free streaming interpolating} model with fixed initial condition has
+been used for the space-time evolution for most central collision at RHIC
+energy. The variation of Bose-Einstein correlation function (BECF), $C_2$, for
+two identical photons as a function of $q_{out}$, $q_{side}$ and $q_{long}$ is
+evaluated. We have restricted our analysis only to QGP phase to know the effect
+of anisotropy on the correlation function and HBT radii extracted. It is
+observed that the longitudinal dimension of the reaction zone is mostly
+affected due to the presence of momentum space anisotropy.",1305.5702v2
+2013-05-26,Giant magnetic anisotropy of transition-metal dimers on defected graphene,"Continuous miniaturization of magnetic units in spintronics and quantum
+computing devices inspires efforts to search for magnetic nanostructures with
+large magnetic anisotropy energy (MAE). Typical nanostructures including
+molecular magnets, magnetic nanoclusters and magnetic nanowires have MAEs of a
+few meV so their blocking temperature is mostly lower than 50 K. In this work,
+we demonstrated the feasibility of achieving giant MAE in systems with
+transition metal dimers on defected and decorated graphene, based on density
+functional theory calculations. In particular, either a Pt-Ir dimer on a single
+vacancy or an Os-Ru dimer on a nitrogen-decorated divacancy possesses an MAE
+larger than 60 meV and high structural stability. Interestingly, their magnetic
+anisotropy can be conveniently manipulated by using external electric field.
+These features make them good candidates for the use in room temperature
+spintronics and quantum computing devices.",1305.5978v4
+2013-06-05,A Dynamical Signature of Multiple Stellar Populations in 47 Tucanae,"Based on the width of its main sequence, and an actual observed split when
+viewed through particular filters, it is widely accepted that 47 Tucanae
+contains multiple stellar populations. In this contribution, we divide the
+main-sequence of 47 Tuc into four color groups, which presumably represent
+stars of various chemical compositions. The kinematic properties of each of
+these groups is explored via proper-motions, and a strong signal emerges of
+differing proper-motion anisotropies with differing main-sequence color; the
+bluest main-sequence stars exhibit the largest proper-motion anisotropy which
+becomes undetectable for the reddest stars. In addition, the bluest stars are
+also the most centrally concentrated. A simiilar analysis for SMC stars, which
+are located in the background of 47 Tuc on our frames, yields none of the
+anisotropy exhibited by the 47 Tuc stars. We discuss implications of these
+results for possible formation scenarios of the various populations.",1306.1226v1
+2013-06-12,The Imaginary Part of the Static Potential in Strongly Coupled Anisotropic Plasma,"Using the gauge/gravity duality we study the imaginary part of the static
+potential associated to the thermal width in finite temperature strongly
+coupled anisotropic plasma. We firstly derive the potential for a generic
+anisotropic background. Then we apply our formulas to a theory where the
+anisotropy has been generated by a space dependent axion term. We find that
+using our method there exist a peculiar turning point in the imaginary part of
+the potential, similar to the one appearing in the real part. The presence of
+anisotropy leads to decrease of the imaginary potential, where larger decrease
+happens along the anisotropic direction when the temperature is kept fixed.
+When the entropy density is fixed, increase happens along the parallel
+direction while along the transverse plane we observe a decrease. To estimate
+the thermal width we use an approximate extrapolation beyond the turning point
+and we find a decrease in presence of the anisotropy, independently of the
+comparison scheme used.",1306.2929v2
+2013-06-18,"Orbital-selective superconductivity, gap anisotropy and spin resonance excitations in a multiorbital t-J1-J2 model for iron pnictides","We study the orbital-dependent superconducting pairing in a five-orbital
+t-J1-J2 model for iron pnictides. Depending on the orbital selectivity of
+electron correlations and the orbital characters along the Fermi surface, the
+superconducting gap in an A_{1g} pairing state may exhibit anisotropy. This
+anisotropy varies with the degree of J1-J2 magnetic frustration. We have also
+calculated the dynamical spin susceptibility in the superconducting state. The
+frequency dependence of the susceptibility at the antiferromagnetic wavevector
+(\pi,0) shows a resonance, whose width is enhanced by the orbital dependence of
+the superconducting gap; when the latter is sufficiently strong, the resonance
+peak may be split into two. We discuss the implications of our results on the
+recent angle-resolved photoemission and neutron-scattering measurements in
+several superconducting iron pnictides.",1306.4184v1
+2013-07-09,Electrical anisotropy of heteroepitaxial InSb/GaAs layers,"We report on study of electrical and structural properties of InSb/GaAs(001)
+heteroepitaxial layers in [110] and [1-10] crystallographic directions. Strong
+anisotropy of electron transport parameters measured at a low magnetic field
+has been found, whereas the electrical transport through the InSb bulk layer
+studied by Shubnikov-de Haas oscillations is shown to be independent of the
+crystallographic directions. The low-field electrical anisotropy of the InSb
+films appears to be governed by two competitive anisotropic effects: influence
+of spontaneously formed In nanoclusters inhomogeneously distributed within the
+InSb layers and conductivity through the near-interface layer with high
+anisotropic density of extended defects.",1307.2368v1
+2013-07-24,The TeV Cosmic-Ray Anisotropy from Local Dark Matter Annihilation,"Several experiments have reported regions in the TeV sky with an excess of
+cosmic rays. Here we consider the possibility that the excess cosmic rays are
+coming from dark matter annihilation in nearby subhalos. We provide motivation
+for dark matter as the source of the excess and show that dark matter
+annihilations can naturally produce the cosmic ray anisotropy without the need
+for exotic dark matter models. We show that viable dark matter explanations of
+the cosmic ray excess are consistent with current measurements of antiprotons,
+positrons, and gamma-rays. Additionally, we show that the dark matter
+interpretation of the observed anisotropy predicts detections in several cosmic
+ray channels by the next generation of experiments.",1307.6537v1
+2013-08-09,Relativistic and thermal effects on the magnon spectrum of a ferromagnetic monolayer,"A spin model including magnetic anisotropy terms and Dzyaloshinsky-Moriya
+interactions is studied for the case of a ferromagnetic monolayer with C2v
+symmetry like Fe/W(110). Using the quasiclassical stochastic
+Landau-Lifshitz-Gilbert equations, the magnon spectrum of the system is derived
+using linear response theory. The Dzyaloshinsky-Moriya interaction leads to
+asymmetry in the spectrum, while the anisotropy terms induce a gap. It is shown
+that in the presence of lattice defects, both the Dzyaloshinsky-Moriya
+interactions and the two-site anisotropy lead to a softening of the magnon
+energies. Two methods are developed to investigate the magnon spectrum at
+finite temperatures. The theoretical results are compared to atomistic spin
+dynamics simulations and a good agreement is found between them.",1308.2082v2
+2013-08-27,Upper Critical Fields and Anisotropy of Ca1-xLaxFe2As2 Single Crystals,"Superconductivity of Ca1-xLaxFe2As2 single crystals with various doping level
+were investigated via electromagnetic measurements for out-plane (H//c) and
+in-plane (H//ab) directions. Obvious double superconducting transitions, which
+can survive in magnetic fields up to several Tesla, were observed in the
+medium-doped (x = 0.13) sample. Two kinds of distinct Hc2 phase diagrams were
+established for the low superconducting phase with Tc lower than 15 K and the
+high superconducting phase with Tc of over 40 K, respectively. Both the two
+kinds of phase diagrams exist in the medium-doped sample. Unusual upward
+curvature near Tc was observed in Hc2 phase diagrams and analyzed in detail.
+Temperature dependences of anisotropy for different doping concentrations were
+obtained and compared. Both superconducting phases manifest extremely large
+anisotropies, which may originate from the interface or intercalation
+superconductivity.",1308.5734v1
+2013-08-31,Quantum Phase Diagram of the Triangular-Lattice XXZ Model in a Magnetic Field,"The triangular lattice of S=1/2 spins with XXZ anisotropy is a ubiquitous
+model for various frustrated systems in different contexts. We determine the
+quantum phase diagram of the model in the plane of the anisotropy parameter and
+the magnetic field by means of a large-size cluster mean-field method with a
+scaling scheme. We find that quantum fluctuations break up the nontrivial
+continuous degeneracy into two first-order phase transitions. In between the
+two transition boundaries, the degeneracy lifting results in the emergence of a
+new coplanar phase not predicted in the classical counterpart of the model. We
+suggest that the quantum phase transition to the nonclassical coplanar state
+can be observed in triangular-lattice antiferromagnets with large easy-plane
+anisotropy or in the corresponding optical-lattice systems.",1309.0086v3
+2013-09-02,Oblique MHD shocks: space-like and time-like,"Shock waves constitute discontinuities in matter which are relevant in
+studying the plasma behaviour in astrophysical scenarios and in heavy-ion
+collision. They can produce conical emission in relativistic collisions and are
+also thought to be the mechanism behind the acceleration of energetic particles
+in active galactic nuclei and gamma ray bursts. The shocks are mostly
+hydrodynamic shocks. In a magnetic background they become magnetohydrodynamic
+(MHD) shocks. For that reason we study the space-like and time-like shock
+discontinuity in a magnetic plasma. The shocks induce a phase transition in the
+plasma, here assuming a transition from hadron to quarks. The MHD conservation
+conditions are derived across the shock. The conservation conditions are solved
+for downstream velocities and flow angles for given upstream variables. The
+shock conditions are solved at different baryon densities. For the space-like
+shocks the anisotropy in the downstream velocity arises due to the magnetic
+field. The downstream velocity vector always points downward with respect to
+the shock normal. With the increase in density the anisotropy is somewhat
+reduced. The magnetic field has effectively no effect on time-like shocks. The
+slight anisotropy in the downstream flow velocities is caused by the boosting
+that brings the quantities from the fluid frame to normal incidence (NI) frame.",1309.0397v1
+2013-09-03,Phase diagram and water-like anomalies in core-softened shoulder-dumbbells system,"Using molecular dynamics we studied the role of the anisotropy on the phase
+boundary and on the anomalous behavior of 250 dimeric particles interacting by
+a core-softened potential. This study led us to an unexpected result: the
+introduction of a rather small anisotropy, quantified by the distance between
+the particles inside each dimer, leads to the increase of the size of the
+regions in the pressure-temperature phase diagram of anomalies when compared to
+the isotropic monomeric case. However, as the anisotropy increases beyond a
+threshold the anomalous regions shrinks. We found that this behavior can be
+understood by decoupling the translational and non-translational kinetic energy
+components into different translational and non-translational temperatures.",1309.0843v1
+2013-09-12,One-Dimensional Dispersive Magnon Excitation in the Frustrated Spin-2 Chain System Ca3Co2O6,"Using inelastic neutron scattering, we have observed a quasi-one-dimensional
+dispersive magnetic excitation in the frustrated triangular-lattice spin-2
+chain oxide Ca3Co2O6. At the lowest temperature (T = 1.5 K), this magnon is
+characterized by a large zone-center spin gap of ~27 meV, which we attribute to
+the large single-ion anisotropy, and disperses along the chain direction with a
+bandwidth of ~3.5 meV. In the directions orthogonal to the chains, no
+measurable dispersion was found. With increasing temperature, the magnon
+dispersion shifts towards lower energies, yet persists up to at least 150 K,
+indicating that the ferromagnetic intrachain correlations survive up to 6 times
+higher temperatures than the long-range interchain antiferromagnetic order. The
+magnon dispersion can be well described within the predictions of linear
+spin-wave theory for a system of weakly coupled ferromagnetic chains with large
+single-ion anisotropy, enabling the direct quantitative determination of the
+magnetic exchange and anisotropy parameters.",1309.3222v2
+2013-09-12,Multiple scattering Sunyaev-Zeldovich signal II: relativistic effects,"We study the multiple scattering Sunyaev-Zeldovich (SZ) signature, extending
+our previous analysis to high-temperature clusters. We consistently treat the
+anisotropy of the ambient radiation field caused by the first scattering and
+also consider lowest order kinematic terms. We show that due to temperature
+corrections monopole through octupole anisotropy of the singly scattered SZ
+signal attain different spectra in the second scattering. The difference
+becomes more pronounced at high temperature, and thus could be used to
+constrain individual line of sight moments of the electron density and
+temperature profiles. While very challenging from the observational point of
+view, this further extends the list of possible SZ observables that will be
+important for 3D cluster-profile reconstruction, possibly helping to break
+geometric degeneracies caused by projection effects. We also briefly discuss
+the scattering of primordial CMB anisotropies by SZ clusters.",1309.3274v2
+2013-10-04,Designing a robustly metallic noncenstrosymmetric ruthenate oxide with large thermopower anisotropy,"The existence of approximately 30 noncentrosymmetric metals (NCSM) suggests a
+contraindication between crystal structures without inversion symmetry and
+metallic behavior. Those containing oxygen are especially scarce. Here we
+propose and demonstrate a design framework to remedy this property disparity
+and accelerate NCSM-oxide discovery: The primary ingredient relies on the
+removal of inversion symmetry through displacements of atoms whose electronic
+degrees of freedom are decoupled from the states at the Fermi level. Density
+functional theory calculations validate this crystal--chemistry strategy, and
+we predict a new polar ruthenate exhibiting robust metallicity. We demonstrate
+that the electronic structure is unaffected by the inclusion of spin-orbit
+interactions (SOI), and that cation ordered SrCaRu$_2$O$_6$ exhibits a large
+thermopower anisotropy ($\left|\Delta\mathcal{S}_\perp\right|\sim6.3 \mu
+\textrm{V K}^{-1}$ at 300 K) derived from its polar structure. Our findings
+provide chemical and structural selection guidelines to aid in the search of
+new NCS metals with enhanced thermopower anisotropy.",1310.1148v2
+2013-10-06,Magnetization Properties and Vortex Phase Diagram in CuxTiSe2 Single Crystals,"We have investigated the magnetization properties and flux dynamics of
+superconducting Cu$_x$TiSe$_2$ single crystals within wide range of copper
+concentrations. We find that the superconducting anisotropy is low and
+independent on copper concentration ($\gamma\sim1.7$), except in the case of
+strongly underdoped samples ($x\leq0.06$) that show a gradual increase in
+anisotropy to $\gamma\sim1.9$. The vortex phase diagram in this material is
+characterized by broad region of vortex liquid phase that is unusual for such
+low-$T_c$ superconductor with low anisotropy. Below the irreversibility line
+the vortex solid state supports relatively low critical current densities as
+compared to the depairing current limit ($J_c/J_0\sim10^{-7}$). All this points
+out that local fluctuations in copper concentration have little effect on bulk
+pinning properties in this system.",1310.1613v1
+2013-10-12,Edge Modes in the Intermediate-D and Large-D Phases of the S=2 Quantum Spin Chain with XXZ and On-Site Anisotropies,"We investigate the edge modes at T=0 in the intermediate-D (ID) phase and the
+large-D (LD) phase of the S=2 quantum spin chain with the XXZ anisotropy and
+the generalized on-site anisotropies by use of the DMRG. There exists a gapless
+edge mode in the ID phase, while no gapless edge mode in the LD phase. These
+results are consistent with the physical pictures of these phases. We also show
+the ground-state phase diagrams obtained by use of the exact diagonalization
+and the level spectroscopy analysis.",1310.3385v1
+2013-10-15,CMB distortion anisotropies due to the decay of primordial magnetic fields,"We investigate the power spectrum of the distortion of Cosmic Microwave
+Background (CMB) due to the decay of the primordial magnetic fields. It is
+known that there are two-types of the CMB distortions, so-called \mu- and
+y-types and we find that the signal of the y-type distortion becomes larger
+than that of the \mu-type one. We also discuss cross power spectra between the
+CMB distortions and the CMB temperature anisotropy, which are naturally
+generated due to the existence of the primordial magnetic fields. We find that
+such cross power spectra have small amplitudes compared with the auto-power
+spectra of the CMB distortions because of the Silk damping effect of the
+temperature anisotropy. We also investigate the possibility of detecting such
+signal in the future CMB experiments, including not only absolutely calibrated
+experiments such as PIXIE but also relatively calibrated experiments such as
+LiteBIRD and CMBpol.",1310.3886v1
+2013-10-22,Thermal conductivity of anisotropic spin - 1/2 two leg ladder:Green's function approach,"We study the thermal transport of a spin-1/2 two leg antiferromagnetic ladder
+in the direction of legs. The possible effect of spin-orbit coupling and
+crystalline electric field are investigated in terms of anisotropies in the
+Heisenberg interactions on both leg and rung couplings. The original spin
+ladder is mapped to a bosonic model via a bond-operator transformation where an
+infinite hard-core repulsion is imposed to constrain one boson occupation per
+site. The Green's function approach is applied to obtain the energy spectrum of
+quasi-particle excitations responsible for thermal transport. The thermal
+conductivity is found to be monotonically decreasing with temperature due to
+increased scattering among triplet excitations at higher temperatures. A tiny
+dependence of thermal transport on the anisotropy in the leg direction at low
+temperatures is observed in contrast to the strong one on the anisotropy along
+the rung direction, due to the direct effect of the triplet density. Our
+results reach asymptotically the ballistic regime of the spin - 1/2 Heisenberg
+chain and compare favorably well with exact diagonalization data.",1310.5943v1
+2013-11-04,Anisotropic g factor in InAs self-assembled quantum dots,"We investigate the wave functions, spectrum, and g-factor anisotropy of
+low-energy electrons confined to self-assembled, pyramidal InAs quantum dots
+(QDs) subject to external magnetic and electric fields. We present the
+construction of trial wave functions for a pyramidal geometry with hard-wall
+confinement. We explicitly find the ground and first excited states and show
+the associated probability distributions and energies. Subsequently, we use
+these wave functions and 8-band $k\cdot p$ theory to derive a Hamiltonian
+describing the QD states close to the valence band edge. Using a perturbative
+approach, we find an effective conduction band Hamiltonian describing
+low-energy electronic states in the QD. From this, we further extract the
+magnetic field dependent eigenenergies and associated g factors. We examine the
+g factors regarding anisotropy and behavior under small electric fields. In
+particular, we find strong anisotropies, with the specific shape depending
+strongly on the considered QD level. Our results are in good agreement with
+recent measurements [Takahashi et al., Phys. Rev. B 87, 161302 (2013)] and
+support the possibility to control a spin qubit by means of g-tensor
+modulation.",1311.0908v2
+2013-11-05,The isotropy problem of Sub-ankle Ultra-high energy cosmic rays,"We study the time dependent propagation of sub-ankle ultra-high energy cosmic
+rays (UHECRs) originating from point-like Galactic sources. We show that drift
+in the Galactic magnetic field (GMF) may play an important role in the
+propagation of UHECRs and their measured anisotropy, particularly when the
+transport is anisotropic. To fully account for the discreteness of UHECR
+sources in space and time, a Monte Carlo method is used to randomly place
+sources in the Galaxy. The low anisotropy measured by Auger is not generally
+characteristic of the theoretical models, given that the sources are
+distributed in proportion to the star formation rate, but it can possibly be
+understood as a) intermittency effects due to the discrete nature of the
+sources or, with extreme parameters, b) a cancellation of drift current along a
+current sheet with the outward radial diffusive flux. We conclude that it is
+possible to interpret the Galactic sub-ankle CR flux as being due entirely to
+intermittent discrete Galactic sources distributed in proportion to star
+formation, but only with probability of roughly 35 percent, of which the
+spectrum is in accord with observations about 30 percent of the time.
+  An alternative explanation for the low anisotropy may be that they are mostly
+extragalactic and/or heavy.",1311.1208v1
+2013-11-08,Curvature effects in statics and dynamics of a thin magnetic shell,"Equations of the magnetization dynamics are derived for an arbitrary curved
+2D surface. General static solutions are obtained in the limit of a strong
+anisotropy of both signs (easy-surface and easy-normal cases). It is shown that
+the effect of the curvature can be treated as appearance of an effective
+magnetic field which is aligned along the surface normal for the case of
+easy-surface anisotropy and it is tangential to the surface for the case of
+easy-normal anisotropy. In general, the existence of such a field denies the
+solutions strictly tangential as well as strictly normal to the surface. As an
+example we consider static equilibrium solutions and linear dynamics for a cone
+surface magnetization.",1311.2026v2
+2013-11-12,Magnetic Coupling and Single-Ion Anisotropy in Surface-Supported Mn-based Metal-Organic Networks,"The electronic and magnetic properties of Mn coordinated to
+1,2,4,5-tetracyanobenzene (TCNB) in the Mn-TCNB 2D metal-ligand networks have
+been investigated by combining scanning tunneling microscopy and X-ray magnetic
+circular dichroism (XMCD) performed at low temperature (3 K). When formed on
+Au(111) and Ag(111) substrates the Mn-TCNB networks display similar geometric
+structures. Magnetization curves reveal ferromagnetic (FM) coupling of the Mn
+sites with similar single-ion anisotropy energies, but different coupling
+constants. Low-temperature XMCD spectra show that the local environment of the
+Mn centers differs appreciably for the two substrates. Multiplet structure
+calculations were used to derive the corresponding ligand field parameters
+confirming an in-plane uniaxial anisotropy. The observed interatomic coupling
+is discussed in terms of superexchange as well as substrate-mediated magnetic
+interactions.",1311.2775v3
+2013-11-25,Target-skyrmions and skyrmion clusters in nanowires of chiral magnets,"In bulk non-centrosymmetric magnets the chiral Dzyaloshinskii-Moriya exchange
+stabilizes tubular skyrmions with a reversed magnetization in their centers.
+While the double-twist is favorable in the center of a skyrmion, it gives rise
+to an excess of the energy density at the outskirt. Therefore, magnetic
+anisotropies are required to make skyrmions more favorable than the conical
+spiral state in bulk materials. Using Monte Carlo simulations, we show that in
+magnetic nanowires unusual skyrmions with a doubly twisted core and a number of
+concentric helicoidal undulations (target-skyrmions) are thermodynamically
+stable even in absence of single-ion anisotropies. Such skyrmions are free of
+magnetic charges and, since the angle describing the direction of magnetization
+at the surface depends on the radius of the nanowire and an applied magnetic
+field, they carry a non-integer skyrmion charge s > 1. This state competes with
+clusters of spatially separated s=1 skyrmions. For very small radii, the
+target-skyrmion transforms into a skyrmion with s < 1, that resembles the
+vortex-like state stabilized by surface-induced anisotropies.",1311.6283v1
+2013-11-28,Direct Measurement of Competing Quantum Effects on the Kinetic Energy of Heavy Water upon Melting,"Even at room temperature, quantum mechanics plays a major role in determining
+the quantitative behaviour of light nuclei, changing significantly the values
+of physical properties such as the heat capacity. However, other observables
+appear to be only weakly affected by nuclear quantum effects (NQEs): for
+instance, the melting temperatures of light and heavy water differ by less than
+4 K. Recent theoretical work has attributed this to a competition between intra
+and inter molecular NQEs, which can be separated by computing the anisotropy of
+the quantum kinetic energy tensor. The principal values of this tensor change
+in opposite directions when ice melts, leading to a very small net quantum
+mechanical effect on the melting point. This paper presents the first direct
+experimental observation of this phenomenon, achieved by measuring the
+deuterium momentum distributions n(p) in heavy water and ice using Deep
+Inelastic Neutron Scattering (DINS), and resolving their anisotropy. Results
+from the experiments, supplemented by a theoretical analysis, show that the
+anisotropy of the quantum kinetic energy tensor can also be captured for
+heavier atoms such as oxygen.",1311.7247v1
+2013-12-04,Non-Gaussianity of the Cosmic Infrared Background anisotropies I : Diagrammatic formalism and application to the angular bispectrum,"We present the first halo model based description of the Cosmic Infrared
+Background (CIB) non-Gaussianity (NG) that is fully parametric. To this end, we
+introduce, for the first time, a diagrammatic method to compute high order
+polyspectra of the 3D galaxy density field. It allows an easy derivation and
+visualisation of the different terms of the polyspectrum. We apply this
+framework to the power spectrum and bispectrum, and we show how to project them
+on the celestial sphere in the purpose of the application to the CIB angular
+anisotropies. Furthermore, we show how to take into account the particular case
+of the shot noise terms in that framework. Eventually, we compute the CIB
+angular bispectrum at 857 GHz and study its scale and configuration
+dependencies, as well as its variations with the halo occupation distribution
+parameters. Compared to a previously proposed empirical prescription, such
+physically motivated model is required to describe fully the CIB anisotropies
+bispectrum. Finally, we compare the CIB bispectrum with the bispectra of other
+signals potentially present at microwave frequencies, which hints that
+detection of CIB NG should be possible above 220 GHz.",1312.1251v1
+2013-12-20,Anisotropy of excitation and relaxation of photogenerated Dirac electrons in graphene,"We investigate the polarization dependence of the carrier excitation and
+relaxation in epitaxial multilayer graphene. Degenerate pump-probe experiments
+with a temporal resolution of 30 fs are performed for different rotation angles
+of the pump-pulse polarization with respect to the polarization of the probe
+pulse. A pronounced dependence of the pump-induced transmission on this angle
+is found. It reflects a strong anisotropy of the pump-induced occupation of
+photogenerated carriers in momentum space even though the band structure is
+isotropic. Within 150 fs after excitation an isotropic carrier distribution is
+established. Our observations imply the predominant role of collinear
+scattering preserving the initially optically generated anisotropy in the
+carrier distribution. The experiments are well described by microscopic time-,
+momentum, and angle-resolved modelling, which allows us to unambiguously
+identify non-collinear carrier-phonon scattering to be the main relaxation
+mechanism giving rise to an isotropic distribution in the first hundred fs
+after optical excitation.",1312.5860v1
+2013-12-30,Cosmic-ray diffusion in collisionless plasmas including pressure anisotropy,"Using a hybrid kinetic magnetohydrodynamic formalism incorporating the
+effects of pressure anisotropy, we simulate the evolution of a turbulent
+collisionless plasma in six different models covering the sub/super-sonic and
+sub/super-Alfv\'enic regimes. Based on the power spectrum of the simulated
+magnetic field, we compute the particle diffusion coefficients for protons with
+kinetic energy in the $50-500$ MeV range, and compare them to those obtained
+within standard magnetohydrodynamics. Our results show that the differences in
+the statistical properties of the magnetic field, generated by pressure
+anisotropy and its associated kinetic instabilities, have an appreciable impact
+on the diffusion coefficients of energetic protons. Moreover, the values of the
+diffusion coefficients that we obtain within each of the six models considered
+vary significantly.",1312.7822v1
+2013-12-31,Dissociation of Quarkonium in a Complex Potential,"We have studied the quasi-free dissociation of quarkonia through a complex
+potential which is obtained by correcting both the perturbative and
+nonperturbative terms of the $Q \bar Q$ potential at T=0 through the dielectric
+function in real-time formalism. The presence of confining nonperturbative term
+even above the transition temperature makes the real-part of the potential more
+stronger and thus makes the quarkonia more bound and also enhances the
+(magnitude) imaginary-part which, in turn contributes more to the thermal
+width, compared to the medium-contribution of the perturbative term alone.
+These cumulative observations result the quarkonia to dissociate at higher
+temperatures. Finally we extend our calculation to a medium, exhibiting local
+momentum anisotropy, by calculating the leading anisotropic corrections to the
+propagators in Keldysh representation. The presence of anisotropy makes the
+real-part of the potential stronger but the imaginary-part is weakened
+slightly. However, since the medium corrections to the imaginary-part is a
+small perturbation to the vacuum part, overall the anisotropy makes the
+dissociation temperatures higher, compared to isotropic medium.",1401.0172v2
+2014-01-27,Edge states in 2D lattices with hopping anisotropy and Chebyshev polynomials,"Analytic technique based on Chebyshev polynomials is developed for studying
+two-dimensional lattice ribbons with hopping anisotropy. In particular, the
+tight-binding models on square and triangle lattice ribbons are investigated
+with anisotropic nearest neighbouring hoppings. For special values of hopping
+parameters the square lattice becomes topologically equivalent to a honeycomb
+one either with zigzag or armchair edges. In those cases as well as for
+triangle lattices we perform the exact analytic diagonalization of
+tight-binding Hamiltonians in terms of Chebyshev polynomials. Deep inside the
+edge state subband the wave functions exhibit exponential spatial damping which
+turns into power-law damping at edge-bulk transition point. It is shown that
+strong hopping anisotropy crashes down edge states, and the corresponding
+critical conditions are found.",1401.6770v2
+2014-02-27,Azimuthal Anisotropy Measurements by STAR,"The recent study of centrality and transverse momentum ($p_{T}$) dependence
+of inclusive charged hardron elliptic anisotropy ($v_{2}$) at midrapidity
+($|\eta|<1.0$) in Au+Au collision at $\sqrt{s_{NN}} =$ 7.7, 11.5, 19.6, 27, and
+39 GeV in STAR Beam Energy Scan program is presented. We show that the observed
+increase of inclusive $v_{2}$ is mainly due to the average $p_{T}$ increase
+with energy. In Au+Au 200 GeV collisions, the triangular anisotropy ($v_{3}$)
+measurements highly depend on measurment methods; $v_{3}$ is strongly dependent
+on $\Delta\eta$. The difference between two- and four-particle cumulants
+$v_{2}\lbrace{2}\rbrace$ and $v_{2}\lbrace{4}\rbrace$ for Au+Au and Cu+Cu
+collision at $\sqrt{s_{NN}} = $ 62.4 and 200 GeV is used to explore flow
+fluctuations. Furthermore, by exploiting the symmetry of average flow in
+pseudorapidity $\eta$ about mid-rapidty, the $\Delta\eta$-dependent and
+independent components are seperated using $v_{2}\lbrace2\rbrace$ and
+$v_{2}\lbrace{4}\rbrace$.",1402.6982v1
+2014-03-03,Azimuthal anisotropies of reconstructed jets in Pb+Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV in a multiphase transport model,"Azimuthal anisotropies of reconstructed jets [$v_{n}^{jet} (n=2, 3)$] have
+been investigated in Pb+Pb collisions at the center of mass energy
+$\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV within a framework of a multiphase transport
+(AMPT) model. The $v_{2}^{jet}$ is in good agreement with the recent ATLAS
+data. However, the $v_{3}^{jet}$ shows a smaller magnitude than $v_{2}^{jet}$,
+and approaches zero at a larger transverse momentum. It is attributed to the
+path-length dependence in which the jet energy loss fraction depends on the
+azimuthal angles with respect to different orders of event planes. The ratio
+$v_{n}^{jet}/\varepsilon_{n}$ increases from peripheral to noncentral
+collisions, and $v_{n}^{jet}$ increases with the initial spatial asymmetry
+($\varepsilon_{n}$) for a given centrality bin. These behaviors indicate that
+the $v_{n}^{jet}$ is produced by the strong interactions between jet and the
+partonic medium with different initial geometry shapes. Therefore, azimuthal
+anisotropies of reconstructed jet are proposed as a good probe to study the
+initial spatial fluctuations, which are expected to provide constraints on the
+path-length dependence of jet quenching models.",1403.0328v2
+2014-03-11,Piezo-Voltage Manipulation of the Magnetization and Magnetic Reversal in Thin Fe Film,"We carefully investigated the in-plane magnetic reversal and corresponding
+magnetic domain structures in Fe/GaAs/piezo-transducer heterostructure using
+longitudinal magneto-optical Kerr microscopy. The coexistence of the <100>
+cubic magnetic anisotropy and uniaxial magnetic anisotropy was observed in our
+Fe thin film grown on GaAs. The induced deformation along [110] orientation can
+effectively manipulate the magnetic reversal with magnetic field applied along
+magnetic uniaxial hard [110] axes. The control of two-jump magnetization
+switching to one-jump magnetization switching during the magnetic reversal was
+achieved by piezo-voltages with magnetic field applied in [100] direction. The
+additional uniaxial anisotropy induced by piezo-voltages at -75 /75V are
+-1.400/1400 J/m3 .",1403.2469v1
+2014-03-11,Relating the inhomogeneous power spectrum to the CMB hemispherical anisotropy,"We relate the observed hemispherical anisotropy in the cosmic microwave
+radiation data to an inhomogeneous power spectrum model. The hemispherical
+anisotropy can be parameterized in terms of the dipole modulation model. This
+model leads to correlations between spherical harmonic coefficients
+corresponding to multipoles, l and l+1. We extract the $l$ dependence of the
+dipole modulation amplitude, A, by making a fit to the WMAP and PLANCK CMBR
+data. We propose an inhomogeneous power spectrum model and show that it also
+leads to correlations between multipoles, l and l+1. The model parameters are
+determined by making a fit to the data. The spectral index of the inhomogeneous
+power spectrum is found to be consistent with zero.",1403.2567v4
+2014-03-19,Coexistence of bunching and meandering instability in simulated growth of 4H-SiC(0001) surface,"Bunching and meandering instability of steps at the 4H-SiC(0001) surface is
+studied by the kinetic Monte Carlo simulation method. Change in the character
+of step instability is analyzed for different rates of particle jumps towards
+step. In the experiment effective value of jump rates can be controlled by
+impurities or other growth conditions. An anisotropy of jump barriers at the
+step influences the character of surface structure formed in the process of
+crystal growth. Depending on the growth parameters different surface patterns
+are found. We show phase diagrams of surface patterns as a function of
+temperature and crystal growth rate for two different choices of step kinetics
+anisotropy. Jump rates which effectively model high inverse Schwoebel barrier
+(ISB) at steps lead either to regular, four-multistep or bunched structure. For
+weak anisotropy at higher temperatures or for lower crystal growth rates
+meanders and mounds are formed, but on coming towards lower temperatures and
+higher rates we observe bunch and meander coexistence. These results show that
+interplay between simple dynamical mechanisms induced by the asymmetry of the
+step kinetics and step movement assisted by the step edge diffusion are
+responsible for different types of surface morphology.",1403.4846v2
+2014-03-25,Spin waves in the anisotropic fcc kagome antiferromagnet,"Spin wave calculations demonstrate that the macroscopic continuous degeneracy
+associated with the two-dimensional kagome Heisenberg spin lattice persists in
+the case of the stacked fcc structure giving rise to zero energy modes in three
+dimensions. The addition of an effective local cubic anisotropy is shown to
+remove this continuous degeneracy and introduce a gap in the spectrum as well
+as modify the inelastic scattering function $S({\bf q},\omega)$. This scenario
+supports earlier Monte Carlo simulations which indicate that the phase
+transition to long range $q=0$ magnetic order is driven to be discontinuous by
+critical fluctuations associated with the large degeneracy in the absence of
+anisotropy, but becomes continuous with the addition of anisotropy. The results
+are relevant to Ir-Mn alloys which are widely used in the magnetic storage
+industry in thin film form as the antiferromagnetic pinning layer in spin-valve
+structures.",1403.6352v1
+2014-03-29,Strong out-of-plane magnetic anisotropy of Fe adatoms on Bi$_2$Te$_3$,"The electronic and magnetic properties of individual Fe atoms adsorbed on the
+surface of the topological insulator Bi$_2$Te$_3$(111) are investigated.
+Scanning tunneling microscopy and spectroscopy prove the existence of two
+distinct types of Fe species, while our first-principles calculations assign
+them to Fe adatoms in the hcp and fcc hollow sites. The combination of x-ray
+magnetic circular dichroism measurements and angular dependent magnetization
+curves reveals out-of-plane anisotropies for both species with anisotropy
+constants of $K_{\text{fcc}} = (10 \pm 4)$ meV/atom and $K_{\text{hcp}} = (8
+\pm 4)$ meV/atom. These values are well in line with the results of
+calculations.",1403.7621v1
+2014-04-02,Multiple Andreev Reflections Spectroscopy of Superconducting LiFeAs Single Crystals: Anisotropy and Temperature Behavior of the Order Parameters,"The superconducting state of LiFeAs single crystals with the maximum critical
+temperature $T_c\,\approx\,17\,K$ in the 111 family has been studied in detail
+by multiple Andreev reflections (MAR) spectroscopy implemented by the
+break-junction technique. The three superconducting gaps, $\Delta_{\Gamma}\,=
+(5.1-6.5)\,meV$, $\Delta_L\,= (3.8-4.8)\,meV$, and $\Delta_S\,= (0.9-1.9)\,meV$
+(at $T\,<<\,T_c$), as well as their temperature dependences, have been directly
+determined in a tunneling experiment with these samples. The anisotropy degrees
+of the order parameters in the k-space have been estimated as $<\,8$%,
+$\approx12$%, and $\approx20$%, respectively. Andreev spectra have been fitted
+within the extended Kummel-Gunsenheimer-Nikolsky model with allowance for
+anisotropy. The relative electron-boson coupling constants in LiFeAs have been
+determined by approximating the ${\Delta}(T)$ dependences by the system of the
+two-band Moskalenko and Suhl equations. It has been shown that the densities of
+states in bands forming ${\Delta}_{\Gamma}$ and ${\Delta}_L$ are approximately
+the same, intraband pairing dominates in this case, and the interband coupling
+constants are related as
+${\lambda}_{{\Gamma}L}\,\approx\,{\lambda}_{L{\Gamma}}\,<<
+{\lambda}_{S{\Gamma}},\,{\lambda}_{SL}$.",1404.0517v1
+2014-04-07,Directional pinning and anisotropy in YBa2Cu3O7-x with BaZrO3 nanorods: intrinsic and nanorods-induced anisotropy,"We present a study of the anisotropic vortex parameters as obtained from
+measurements of the microwave complex resistivity in the vortex state with a
+tilted applied magnetic field in YBa2Cu3O7-x thin films with BaZrO3 nanorods.
+We present the angular dependence of the vortex viscosity $\eta$, the pinning
+constant k_p and the upper limit for the creep factor \chi_M. We show that the
+directional effect of the nanorods is absent in \eta, which is dictated by the
+mass anisotropy \gamma. By contrast, pinning-mediated properties are strongly
+affected by the nanorods. It is significant that the pinning and creep affected
+by the nanorods is detectable also at our very high operating frequency, which
+implies very short-range displacements of the vortices from their equilibrium
+position.",1404.1670v1
+2014-04-15,A second-order spin-flop transition in collinear two-sublattice antiferromagnets,"Identifying the nature of a spin-flop (SFO) transition, first- or
+second-order (FO or SO), remains a major challenge in condensed-matter physics
+due to the technically undistinguishable effect of misalignment between
+applied-field direction and the relevant antiferromagnetic (AFM) easy axis. A
+classical SFO transition is believed to be of FO in character. Here a
+mean-field theoretical calculation endowed with AFM exchange interaction
+(\emph{J}), easy axis anisotropy ($\gamma$), uniaxial single-ion exchange
+anisotropy (\emph{D}), and Zeeman coupling to a magnetic field parallel to the
+easy axis unambiguously reveals that a SO SFO transition indeed exists by
+virtue of its relatively lower free energy. Their equilibrium phase conditions
+are found to be: $D \geq 0$ (FO); $-\frac{1}{2} \gamma < D < 0$ (SO). Compared
+numerically to the associated AFM and spin-flip phases, the deduced SO SFO
+transition results from a negative single-ion anisotropy which is restricted to
+a certain range by the anisotropic exchange interaction",1404.3914v1
+2014-04-16,Momentum anisotropy in nuclear collisions from quantum mechanics,"We point out that the intrinsic relationship between space and momentum in
+quantum physics through the uncertainty principle has potential implications
+for momentum anisotropy in heavy-ion collisions. Using a harmonic oscillator
+potential we calculate the elliptic anisotropy and find it to be sizeable
+compared to elliptic flow measurements in nuclear collisions. Our results
+question the validity of the completely hydrodynamic interpretation of
+anisotropic flow data, and highlight the importance of including quantum
+physics in hydrodynamic calculations which has largely been neglected so far.",1404.4119v2
+2014-05-06,Polarization of Direct Photons from Gluon Anisotropy in Ultrarelativistic Heavy Ion Collisions,"We show how anisotropy in momentum of the gluon distribution in
+ultrarelativistic heavy ion collisions gives rise to polarization of direct
+photons produced via gluon-quark Compton scattering, as well as by
+quark-antiquark annihilation into a gluon-photon pair. We estimate the
+polarization asymmetry from the Compton process within a toy model where the
+polarized photons are produced from thermal gluons scattered by heavy-quark
+scattering centers moving with Bjorken boost-invariant flow, and find that it
+could be as large as 10%. We conclude that polarization measurements of
+directly produced photons can shed light on gluon pressure anisotropy in the
+early stages of collisions.",1405.1376v2
+2014-05-09,Phase diagram of two-dimensional hard ellipses,"We report the phase diagram of two-dimensional hard ellipses as obtained from
+replica exchange Monte Carlo simulations. The replica exchange is implemented
+by expanding the isobaric ensemble in pressure. The phase diagram shows four
+regions: isotropic, nematic, plastic, and solid (letting aside the hexatic
+phase at the isotropic-plastic two-step transition [PRL 107, 155704 (2011)]).
+At low anisotropies, the isotropic fluid turns into a plastic phase which in
+turn yields a solid for increasing pressure (area fraction). Intermediate
+anisotropies lead to a single first order transition (isotropic-solid).
+Finally, large anisotropies yield an isotropic-nematic transition at low
+pressures and a high-pressure nematic-solid transition. We obtain continuous
+isotropic-nematic transitions. For the transitions involving quasi-long-range
+positional ordering, i. e. isotropic-plastic, isotropic-solid, and
+nematic-solid, we observe bimodal probability density functions. This supports
+first order transition scenarios.",1405.2236v1
+2014-05-14,Magnetic anisotropy of spin tetramer system SeCuO$_3$ studied by torque magnetometry and ESR spectroscopy,"We present an experimental study of macroscopic and microscopic magnetic
+anisotropy of a spin tetramer system SeCuO$_3$ using torque magnetometry and
+ESR spectroscopy. Large rotation of macroscopic magnetic axes with temperature
+observed from torque magnetometry agrees reasonably well with the rotation of
+the $\textbf{g}$ tensor above $T \gtrsim 50$~K. Below 50~K, the $\textbf{g}$
+tensor is temperature independent, while macroscopic magnetic axes continue to
+rotate. Additionally, the susceptibility anisotropy has a temperature
+dependence which cannot be reconciled with the isotropic Heisenberg model of
+interactions between spins. ESR linewidth analysis shows that anisotropic
+exchange interaction must be present in SeCuO$_3$. These findings strongly
+support the presence of anisotropic exchange interactions in the Hamiltonian of
+the studied system. Below $T_N=8$~K, the system enters a long - range
+antiferromagnetically ordered state with easy axis along the $<\bar{1} 0 1>^*$
+direction. Small but significant rotation of magnetic axes is also observed in
+the antiferromagnetically ordered state suggesting strong spin-lattice coupling
+in this system.",1405.3389v2
+2014-05-16,Grid induced noise and entropy growth in 3d particle-in-cell simulation of high intensity beams,"The numerical noise inherent to particle-in-cell simulation of 3D high
+intensity bunched beams is studied with the TRACEWIN code and compared with an
+analytical model by Struckmeier. The latter assumes that entropy growth can be
+related to Markov type stochastic processes due to temperature anisotropy and
+the artificial collisions caused by using macro-particles and calculating the
+space charge effect. The resulting noise can lead to growth of the
+six-dimensional rms emittance and a suitably defined rms entropy. We confirm
+the dependence of this growth on the bunch temperature anisotropy as predicted
+by Struckmeier. However,we also find an apparently modified mechanism of noise
+generation by the non-Liouvillean effect of the Poisson solver grid, which
+exists in periodic focusing systems even in the complete absence of temperature
+anisotropy. Our findings are applicable in particular to high current linac
+simulation, where they can provide guidance to estimate noise effects and help
+finding an effective balance between the number of simulation particles and the
+grid resolution.",1405.4153v1
+2014-06-04,Magnetic hard-axis ordering near ferromagnetic quantum criticality,"We investigate the interplay of quantum fluctuations and magnetic
+anisotropies in metallic ferromagnets. Our central result is that fluctuations
+close to a quantum critical point can drive the moments to point along a
+magnetic hard axis. As a proof of concept, we show this behavior explicitly for
+a generic two-band model with local Coulomb and Hund's interactions, and a
+spin-orbit-induced easy plane anisotropy. The phase diagram is calculated
+within the fermionic quantum order-by-disorder approach, which is based on a
+self-consistent free energy expansion around a magnetically ordered state with
+unspecified orientation. Quantum fluctuations render the transition of the
+easy-plane ferromagnet first-order below a tricritical point. At even lower
+temperatures, directionally dependent transverse fluctuations dominate the
+magnetic anisotropy and the moments flip to lie along the magnetic hard axis.
+We discuss our findings in the context of recent experiments that show this
+unusual ordering along the magnetic hard direction.",1406.1173v2
+2014-06-05,Skyrmion fractionalization and merons in chiral magnets with easy-plane anisotropy,"We study the equilibrium phase diagram of ultrathin chiral magnets with
+easy-plane anisotropy $A$. The vast triangular skyrmion lattice phase that is
+stabilized by an external magnetic field evolves continuously as a function of
+increasing $A$ into a regime in which nearest-neighbor skyrmions start
+overlapping with each other. This overlap leads to a continuous reduction of
+the skyrmion number from its quantized value $Q=1$ and to the emergence of
+antivortices at the center of the triangles formed by nearest-neighbor
+skyrmions. The antivortices also carry a small ""skyrmion number"" $Q_A \ll 1$
+that grows as a function of increasing $A$. The system undergoes a first order
+phase transition into a square vortex-antivortex lattice at a critical value of
+$A$. Finally, a canted ferromagnetic state becomes stable through another first
+order transition for a large enough anisotropy $A$. Interestingly enough, this
+first order transition is accompanied by {\it metastable} meron solutions.",1406.1422v3
+2014-06-20,Dependence of the Cosmic Microwave Background Lensing Power Spectrum on the Matter Density,"The anisotropies in the cosmic microwave background (CMB) provide our best
+laboratory for testing models of the formation and evolution of large-scale
+structure. The rich features in the cosmic microwave background anisotropy
+spectrum, in combination with highly precise observations and theoretical
+predictions, also allow us to simultaneously constrain a number of cosmological
+parameters. As observations have progressed, measurements at smaller angular
+scales have provided increasing leverage. These smaller angular scales provide
+sensitive measures of the matter density through the effect of gravitational
+lensing. In this work we provide an analytic explanation of the manner in which
+the lensing of CMB anisotropies depends on the matter density, finding that the
+dominant effect comes from the shape of the matter power spectrum set by the
+decay of small-scale potentials between horizon crossing and matter-radiation
+equality.",1406.5459v2
+2014-06-26,Growth and angular dependent resistivity of Nb2Pd0.73S5.7 superconducting single crystals fiber,"We report the growth of Nb2Pd0.73S5.7 superconducting single crystal fibers
+via slow cooling solid state reaction method. Superconducting transition
+temperature (Tc ~ 6.5K) is confirmed from magnetization and transport
+measurements. A comparative study is performed for determination of
+superconducting anisotropy, {\Gamma}, via conventional method (by taking ration
+of two superconducting parameters) and scaling approach method. Scaling
+approach, defined within the framework of the Ginzburg-Landau theory is applied
+to the angular dependent resistivity measurements to estimate the anisotropy.
+The value of {\Gamma} close to Tc from scaling approach is found to be ~ 2.5
+that is slight higher compare to conventional approach (~2.2). Further,
+variation of anisotropy with temperature suggests that it is a type of
+multi-band superconductor.",1406.6790v2
+2014-06-29,Azimuthal anisotropy in U+U collisions at STAR,"The azimuthal anisotropy of particle production is commonly used in
+high-energy nuclear collisions to study the early evolution of the expanding
+system. The prolate shape of uranium nuclei makes it possible to study how the
+geometry of the colliding nuclei affects final state anisotropies. It also
+provides a unique opportunity to understand how entropy is produced in heavy
+ion collisions. In this paper, the two- and four- particle cumulant $v_2$
+($v_{2}\{2\}$ and $v_{2}\{4\}$) from U+U collisions at $\sqrt{s_{NN}}$ = 193
+GeV and Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV for inclusive charged
+hadrons will be presented. The STAR Zero Degree Calorimeters are used to select
+very central collisions. Differences were observed between the multiplicity
+dependence of $v_{2}\{2\}$ for most central Au+Au and U+U collisions. The
+multiplicity dependence of $v_{2}\{2\}$ in central collisions were compared to
+Monte Carlo Glauber model predictions and it was seen that this model cannot
+explain the present results.",1406.7522v1
+2014-07-01,Emergent defect states as a source of resistivity anisotropy in the nematic phase of iron pnictides,"We consider the role of potential scatterers in the nematic phase of Fe-based
+superconductors above the transition temperature to the (pi,0) magnetic state
+but below the orthorhombic structural transition. The anisotropic spin
+fluctuations in this region can be frozen by disorder, to create elongated
+magnetic droplets whose anisotropy grows as the magnetic transition is
+approached. Such states act as strong anisotropic defect potentials which
+scatter with much higher probability perpendicular to their length than
+parallel, although the actual crystal symmetry breaking is tiny. We calculate
+the scattering potentials, relaxation rates, and conductivity in this region,
+and show that such emergent defect states are essential for the transport
+anisotropy observed in experiments.",1407.0117v1
+2014-07-10,Effects of cosmic strings with delayed scaling on CMB anisotropy,"The network of cosmic strings generated in a phase transition during
+inflation enters the scaling regime later than that of usual strings. If it
+occurs after the recombination, temperature anisotropies of the cosmic
+microwave background (CMB) at high multipole moments are significantly reduced.
+In this paper, we study such effects qualitatively and show that the constraint
+on the cosmic string tension from the CMB temperature anisotropies and B-mode
+polarizations can be relaxed. It is shown to be difficult to explain the recent
+BICEP2 and POLARBEAR results in terms of signals induced by cosmic strings
+alone even if we take into account the delayed scaling. However, the
+inflationary tensor-to-scalar ratio required to explain the observed B-mode
+signals can be slightly reduced to be consistent with the Planck constraint.",1407.2951v2
+2014-07-11,A 4-fold-symmetry hexagonal ruthenium for magnetic heterostructures exhibiting enhanced perpendicular magnetic anisotropy and tunnel magnetoresistance,"An unusual crystallographic orientation of hexagonal Ru with a 4-fold
+symmetry emerging in epitaxial MgO/Ru/Co2FeAl/MgO heterostructures is reported,
+in which an approximately Ru(02-23) growth attributes to the lattice matching
+among MgO, Ru, and Co2FeAl. Perpendicular magnetic anisotropy of the
+Co2FeAl/MgO interface is substantially enhanced as compared with those with a
+Cr(001) layer. The MTJs incorporating this structure gave rise to the largest
+tunnel magnetoresistance for perpendicular MTJs using low damping Heusler
+alloys. The 4-fold-symmetry hexagonal Ru arises from an epitaxial growth with
+an unprecedentedly high crystal index, opening a unique pathway for the
+development of perpendicular anisotropy films of cubic and tetragonal
+ferromagnetic alloys.",1407.3160v2
+2014-07-21,Mapping the Integrated Sachs-Wolfe Effect,"On large scales, the anisotropies in the cosmic microwave background (CMB)
+reflect not only the primordial field but also the energy gain when photons
+traverse decaying gravitational potentials of large scales structure, the
+Integrated Sachs-Wolfe (ISW) effect. Decomposing the anisotropy signal into a
+primordial piece and an ISW component is more urgent than ever as cosmologists
+strive to understand the Universe on the largest of scales. Here we present a
+likelihood technique for extracting the ISW signal from measurements of the
+CMB, the distribution of galaxies, and maps of gravitational lensing. We test
+this technique first to simulated data and then we apply it to the combination
+of temperature anisotropies, the lensing map made by the Planck satellite, and
+the NVSS galaxy survey. We also show projections for upcoming surveys.",1407.5623v2
+2014-08-02,Bending strain-tunable magnetic anisotropy in Co2FeAl Heusler thin film on Kapton,"Bending effect on the magnetic anisotropy in 20 nm Co$_{2}$FeAl Heusler thin
+film grown on Kapton\textregistered{} has been studied by ferromagnetic
+resonance and glued on curved sample carrier with various radii. The results
+reported in this letter show that the magnetic anisotropy is drastically
+changed in this system by bending the thin films. This effect is attributed to
+the interfacial strain transmission from the substrate to the film and to the
+magnetoelastic behavior of the Co$_{2}$FeAl film. Moreover two approaches to
+determine the in-plane magnetostriction coefficient of the film, leading to a
+value that is close to $\lambda^{CFA}=14\times10^{-6}$, have been proposed.",1408.0379v1
+2014-08-05,Azimuthal Anisotropy Distributions in High-Energy Collisions,"Elliptic flow in ultrarelativistic heavy-ion collisions results from the
+hydrodynamic response to the spatial anisotropy of the initial density profile.
+A long-standing problem in the interpretation of flow data is that
+uncertainties in the initial anisotropy are mingled with uncertainties in the
+response. We argue that the non-Gaussianity of flow fluctuations in small
+systems can be used to disentangle the initial state from the response. We
+apply this method to recent measurements of anisotropic flow in Pb+Pb and p+Pb
+collisions at the LHC. The response coefficient is found to decrease mildly as
+the system becomes smaller. This mild decrease is consistent with a low value
+of the ratio of viscosity over entropy.",1408.0921v3
+2014-08-09,CMB statistical anisotropies of classical and quantum origins,"We examine the impact of different anisotropic relics on inflation, in
+particular the predictions on the density perturbations. These relics can be
+the source of the large scale anomalies in the cosmic microwave background.
+There are two different types of background relics, one from the matter sector
+and the other purely from the metric. Although the angular-dependence of the
+statistical anisotropy in both cases are degenerate, the scale-dependence are
+observationally distinctive. In addition, we demonstrate that non-Bunch-Davies
+vacuum states can extend the statistical anisotropy to much shorter scales, and
+leave a scale-dependence that is insensitive to the different backgrounds but
+sensitive to the initial quantum state.",1408.2096v1
+2014-08-12,Modification of perpendicular magnetic anisotropy and domain wall velocity in Pt/Co/Pt by voltage-induced strain,"The perpendicular magnetic anisotropy K$_e$$_f$$_f$, magnetization reversal,
+and field-driven domain wall velocity in the creep regime are modified in
+Pt/Co(0.85-1.0 nm)/Pt thin films by strain applied via piezoelectric
+transducers. K$_e$$_f$$_f$, measured by the extraordinary Hall effect, is
+reduced by 10 kJ/m$^3$ by tensile strain out-of-plane {\epsilon}$_z$ = 9 x
+10-4, independently of the film thickness, indicating a dominant volume
+contribution to the magnetostriction. The same strain reduces the coercive
+field by 2-4 Oe, and increases the domain wall velocity measured by wide-field
+Kerr microscopy by 30-100 %, with larger changes observed for thicker Co
+layers. We consider how strain-induced changes in the perpendicular magnetic
+anisotropy can modify the coercive field and domain wall velocity.",1408.2664v2
+2014-08-12,Nematic spin correlations in the tetragonal state of uniaxial strained BaFe2-xNixAs2,"Understanding the microscopic origins of electronic phases in high-transition
+temperature (high-Tc) superconductors is important for elucidating the
+mechanism of superconductivity. In the paramagnetic tetragonal phase of
+BaFe2-xTxAs2 (where T is Co or Ni) iron pnictides, an in-plane resistivity
+anisotropy has been observed. Here we use inelastic neutron scattering to show
+that low-energy spin excitations in these materials change from four-fold
+symmetric to two-fold symmetric at temperatures corresponding to the onset of
+the in-plane resistivity anisotropy. Because resistivity and spin excitation
+anisotropies both vanish near optimal superconductivity, we conclude that they
+are likely intimately connected.",1408.2756v1
+2014-08-13,p-wave Superfluidity by Spin-Nematic Fermi Surface Deformation,"We study attractively interacting fermions on a square lattice with
+dispersion relations exhibiting strong spin-dependent anisotropy. The resulting
+Fermi surface mismatch suppresses the s-wave BCS-type instability, clearing the
+way for unconventional types of order. Unbiased sampling of the Feynman
+diagrammatic series using Diagrammatic Monte Carlo methods reveals a rich phase
+diagram in the regime of intermediate coupling strength. Instead of a proposed
+Cooper-pair Bose metal phase [A. E. Feiguin and M. P. A. Fisher, Phys. Rev.
+Lett. 103, 025303 (2009)] we find an incommensurate density wave at strong
+anisotropy and two different p-wave superfluid states with unconventional
+symmetry at intermediate anisotropy.",1408.3119v2
+2014-08-18,Ground-State Phases of Anisotropic Mixed Diamond Chains with Spins 1 and 1/2,"The ground-state phases of anisotropic mixed diamond chains with spins 1 and
+1/2 are investigated. Both single-site and exchange anisotropies are
+considered. We find the phases consisting of an array of uncorrelated spin-1
+clusters separated by singlet dimers. Except in the simplest case where the
+cluster consists of a single $S=1$ spin, this type of ground state breaks the
+translational symmetry spontaneously. Although the mechanism leading to this
+type of ground state is the same as that in the isotropic case, it is
+nonmagnetic or paramagnetic depending on the competition between two types of
+anisotropy. We also find the N\'eel, period-doubled N\'eel, Haldane, and
+large-$D$ phases, where the ground state is a single spin cluster of infinite
+size equivalent to the spin-1 Heisenberg chain with alternating anisotropies.
+The ground-state phase diagrams are determined for typical sets of parameters
+by numerical analysis. In various limiting cases, the ground-state phase
+diagrams are determined analytically. The low-temperature behaviors of magnetic
+susceptibility and entropy are investigated to distinguish each phase by
+observable quantities. The relationship of the present model with the
+anisotropic rung-alternating ladder with spin-1/2 is also discussed.",1408.3890v2
+2014-08-27,Chiral Magnetic Effect in the Anisotropic Quark-Gluon Plasma,"An anisotropic thermal plasma phase of a strongly coupled gauge theory can be
+holographically modelled by an anisotropic AdS black hole. The temperature and
+anisotropy parameter of the AdS black hole background of interest [1] is
+specified by the location of the horizon and the value of the Dilaton field at
+the horizon. Interestingly, for the first time, we obtain two functions for the
+values of the horizon and Dilaton field in terms of the temperature and
+anisotropy parameter. Then by introducing a number of spinning probe D7-branes
+in the anisotropic background, we compute the value of the chiral magnetic
+effect (CME). We observe that in the isotropic and anisotropic plasma the value
+of the CME is equal for the massless quarks. However, at fixed temperature,
+raising the anisotropy in the system will increase the value of the CME for the
+massive quarks.",1408.6361v2
+2014-08-30,Anisotropic resistivity of the monolayer graphene in the trigonal warping and connected Fermi curve regimes,"In the present study, the anisotropic resistivity of the monolayer graphene
+has been obtained in semiclassical regime beyond the Dirac point approximation.
+In particular, detailed investigations were made on the dependence of
+conductivity on the Fermi energy. At low energies, in the vicinity of the Dirac
+points, band energy of the monolayer graphene is isotropic at the Fermi level.
+Meanwhile, at the intermediate Fermi energies anisotropic effects such as
+trigonal warping is expected to be the origin of the anisotropic resistivity.
+However, besides the band anisotropy there also exists an other source of
+anisotropic resistivity which was introduced by scattering matrix. At high
+energies it was shown that the band anisotropy is less effective than the
+anisotropy generated by the scattering matrix. It was also shown that there
+exist two distinct regimes of anisotropic resistivity corresponding the
+trigonal warping and connected Fermi curve at intermediate and high energies
+respectively.",1409.0130v1
+2014-09-03,Strong Thermal Transport Anisotropy and Strain Modulation in Single-Layer Phosphorene,"Using first-principles calculations and non-equilibrium Green's function
+method, we investigate the ballistic thermal transport in single-layer
+phosphorene. A significant crystallographic orientation dependence of thermal
+conductance is observed, with room temperature thermal conductance along zigzag
+direction being 40 percent higher than that along armchair direction.
+Furthermore, we find that the thermal conductance anisotropy with the
+orientation can be tuned by applying strain. In particular, the zigzag-oriented
+thermal conductance is enhanced when a zigzag-oriented strain is applied but
+decreases when an armchair-oriented strain is applied; whereas the
+armchair-oriented thermal conductance always decreases when either a zigzag- or
+an armchair-oriented strain is applied. The present work suggests that the
+remarkable thermal transport anisotropy and its strain-modulated effect in
+single-layer phosphorene may be used for thermal management in
+phosphorene-based electronics and optoelectronic devices.",1409.0974v1
+2014-09-04,Dimensional cross-over of the bandgap transition in quasi-two-dimensional MoS2,"The anisotropy of the electronic transition is an important physical property
+not only determining the materials' optical property, but also revealing the
+underlying character of the electronic states involved. Here we used
+momentum-resolved electron energy-loss spectroscopy to study the evolution of
+the anisotropy of the electronic transition involving the low energy valence
+electrons in the free-standing MoS2 systems as the layer thickness was reduced
+to monolayer. We used the orientation and the spectral-density analysis to show
+that indirect to direct band-gap transition is accompanied by a three- to
+two-dimensional anisotropy cross-over. The result provides a logical
+explanation for the large sensitivity of indirect transition to the change of
+thickness compared with that for direct transition. By tracking the energy of
+indirect transition, we also revealed the asymmetric response of the valence
+band and conduction band to the quantum confinement effect. Our results have
+implication for future optoelectronic applications of atomic thin MoS2.",1409.1409v1
+2014-09-08,Anisotropy of spin-orbit induced electron spin relaxation in [001] and [111] grown GaAs quantum dots,"We report a systematic study of the spin relaxation anisotropy between single
+electron Zeeman sublevels in cuboidal GaAs quantum dots (QDs). The QDs are
+subject to an in-plane magnetic field. As the field orientation varies, the
+relaxation rate oscillates periodically, showing ``magic'' angles where the
+relaxation rate is suppressed by several orders of magnitude. This behavior is
+found in QDs with different shapes, heights, crystallographic orientations and
+external fields. The origin of these angles can be traced back to the
+symmetries of the spin admixing terms of the Hamiltonian. In [001] grown QDs,
+the suppression angles are different for Rashba and Dresselhaus spin-orbit
+terms. By contrast, in [111] grown QDs they are the same, which should
+facilitate a thorough suppression of spin-orbit induced relaxation. Our results
+evidence that cubic Dresselhaus terms play a critical role in determining the
+spin relaxation anisotropy even in quasi-2D QDs.",1409.2392v1
+2014-09-09,Micro-strip ferromagnetic resonance study of strain-induced anisotropy in amorphous FeCuNbSiB film on flexible substrate,"The magnetic anisotropy of a FeCuNbSiB (Finemet) film deposited on Kapton has
+been studied by micro-strip ferromagnetic resonance technique. We have shown
+that the flexibility of the substrate allows a good transmission of elastic
+strains generated by a piezoelectric actuator. Following the resonance field
+angular dependence, we also demonstrate the possibility of controlling the
+magnetic anisotropy of the film by applying relatively small voltages to the
+actuator. Moreover, a suitable model taking into account the effective elastic
+strains measured by digital image correlation and the effective elastic
+coefficients measured by Brillouin light scattering, allowed to deduce the
+magnetostrictive coefficient. This latter was found to be positive
+$(\lambda=16\times10^{-6}$) and consistent with the usually reported values for
+bulk amorphous FeCuNbSiB.",1409.2845v1
+2014-09-29,Self-Gravitating Relativistic Models of Fermions with Anisotropy and Cutoff Energy in their Distribution Function,"In this paper we study the equilibrium configurations of anisotropic
+self-gravitating fermions, by extending to general relativity the solutions
+obtained in a previous paper. This treatment also generalizes to anisotropic
+systems the relativistic self-gravitating Fermi gas model, by considering
+different degrees of anisotropy. We discuss some important characteristics of
+the models and the obtained density profiles, and generalize the relation
+between the anisotropy and the mass of particles in the relativistic regime.
+These relativistic models may also be applied to the study of superdense
+neutron stars with anisotropic pressure or super-Chandrasekhar white dwarfs
+generated by the presence of a magnetic field.",1409.8124v4
+2014-10-23,The Effects of Rayleigh Scattering on the CMB and Cosmic Structure,"During and after recombination, in addition to Thomson scattering with free
+electrons, photons also coupled to neutral hydrogen and helium atoms through
+Rayleigh scattering. This coupling influences both CMB anisotropies and the
+distribution of matter in the Universe. The frequency-dependence of the
+Rayleigh cross section breaks the thermal nature of CMB temperature and
+polarization anisotropies and effectively doubles the number of variables
+needed to describe CMB intensity and polarization statistics, while the
+additional atomic coupling changes the matter distribution and the lensing of
+the CMB. We introduce a new method to capture the effects of Rayleigh
+scattering on cosmological power spectra. Rayleigh scattering modifies CMB
+temperature and polarization anisotropies at the $\sim\!1 \%$ level at $353
+{\rm GHz}$ (scaling $\propto \nu^4$), and modifies matter correlations by as
+much as $\sim\!0.3\%$. We show the Rayleigh signal, especially the
+cross-spectra between the thermal (Rayleigh) E-polarization and Rayleigh
+(thermal) intensity signal, may be detectable with future CMB missions even in
+the presence of foregrounds, and how this new information might help to better
+constrain the cosmological parameters.",1410.6484v1
+2014-11-10,Effect of anisotropy on HBT radii using leptonpair interferometry,"The effect of initial state momentum-space anisotropy on invariant mass
+dependence of HBT radii extracted from the leptonpair interferometry is
+presented here. We have studied the Bose-Einstein Correlation Function (BECF)
+for two identical virtual photons decaying to leptonpairs at most central
+collision of LHC energy having fixed transverse momentum of one of the virtual
+photons ($k_{1T}$= 2 GeV). The {\em free streaming interpolating} model with
+fixed initial condition has been used for the evolution in anisotropic Quark
+Gluon Plasma (aQGP) and the relativistic (1+2)d hydrodynamics model with
+cylindrical symmetry and longitudinal boost invariance has been used for both
+isotropic Quark Gluon Plasma (iQGP) and hadronic phases. We found a significant
+change in the spatial and temporal dimension of the evolving system in presence
+of initial state momentum-space anisotropy.",1411.2322v1
+2014-11-14,Photo-induced magnetization enhancement in two-dimensional weakly anisotropic Heisenberg magnets,"By comparing the photo-induced magnetization dynamics in simple layered
+systems we show how light-induced modifications of the magnetic anisotropy
+directly enhance the magnetization. It is observed that the spin precession in
+(CH3NH3)2CuCl4, initiated by a light pulse, increases in amplitude at the
+critical temperature TC. The phenomenon is related to the dependence of the
+critical temperature on the axial magnetic anisotropy. The present results
+underline the possibility and the importance of the optical modifications of
+the anisotropy, opening new paths toward the control of the magnetization state
+for ultrafast memories.",1411.3918v1
+2014-11-21,Holographic renormalization and anisotropic black branes in higher curvature gravity,"We consider five-dimensional AdS-axion-dilaton gravity with a Gauss-Bonnet
+term and find a solution of the equations of motion which corresponds to a
+black brane exhibiting a spatial anisotropy, with the source of the anisotropy
+being an axion field linear in one of the horizon coordinates. Our solution is
+static, regular everywhere on and outside the horizon, and asymptotically AdS.
+It is analytic and valid in a small anisotropy expansion, but fully
+non-perturbative in the Gauss-Bonnet coupling. We discuss various features of
+this solution and use it as a gravity dual to a strongly coupled anisotropic
+plasma with two independent central charges, $a\neq c$. In the limit of small
+Gauss-Bonnet coupling, we carry out holographic renormalization of the system
+using (a recursive variant of) the Hamilton-Jacobi method and derive a generic
+expression for the boundary stress tensor, which we later specialize to our
+solution. Finally, we compute the shear viscosity to entropy ratios and
+conductivities of this anisotropic plasma.",1411.5964v2
+2014-12-04,CMB anisotropies generated by a stochastic background of primordial magnetic fields with non-zero helicity,"We consider the impact of a stochastic background of primordial magnetic
+fields with non-vanishing helicity on CMB anisotropies in temperature and
+polarization. We compute the exact expressions for the scalar, vector and
+tensor part of the energy-momentum tensor including the helical contribution,
+by assuming a power-law dependence for the spectra and a comoving cutoff which
+mimics the damping due to viscosity. We also compute the parity-odd correlator
+between the helical and non-helical contribution which generate the TB and EB
+cross-correlation in the CMB pattern. We finally show the impact of including
+the helical term on the power spectra of CMB anisotropies up to multipoles with
+ell ~ O(10^3)$.",1412.1836v2
+2014-12-10,Anisotropic charged impurity-limited carrier mobility in monolayer phosphorene,"The room temperature carrier mobility in atomically thin 2D materials is
+usually far below the intrinsic limit imposed by phonon scattering as a result
+of scattering by remote charged impurities in its environment. We simulate the
+charged impurity-limited carrier mobility $\mu$ in bare and encapsulated
+monolayer phosphorene. We find a significant temperature dependence in the
+carrier mobilities ($\mu \propto T^{-\gamma}$) that results from the
+temperature variability of the charge screening and varies with the crystal
+orientation. The anisotropy in the effective mass leads to an anisotropic
+carrier mobility, with the mobility in the armchair direction about one order
+of magnitude larger than in the zigzag direction. In particular, this mobility
+anisotropy is enhanced at low temperatures and high carrier densities. Under
+encapsulation with a high-$\kappa$ overlayer, the mobility increases by up to
+an order of magnitude although its temperature dependence and its anisotropy
+are reduced.",1412.3211v1
+2014-12-10,Shape-sensitive Pauli blockade in a bent carbon nanotube,"Motivated by a recent experiment [F. Pei et al., Nat. Nanotech. 7, 630
+(2012)], we theoretically study the Pauli blockade transport effect in a double
+quantum dot embedded in a bent carbon nanotube. We establish a model for Pauli
+blockade, taking into account the strong g-factor anisotropy that is linked to
+the local orientation of the nanotube axis in each quantum dot. We provide a
+set of conditions under which our model is approximately mapped to the
+spin-blockade model of Jouravlev and Nazarov [O. N. Jouravlev and Y. V.
+Nazarov, Phys. Rev. Lett. 96, 176804 (2006)]. The results we obtain for the
+magnetic anisotropy of the leakage current, together with their qualitative
+geometrical explanation, provide a possible interpretation of previously
+unexplained experimental results. Furthermore, we find that in a certain
+parameter range, the leakage current becomes highly sensitive to the shape of
+the tube, and this sensitivity increases with increasing g-factor anisotropy.
+This mutual dependence of the electron transport and the tube shape allows for
+mechanical control of the leakage current, and for characterization of the tube
+shape via measuring the leakage current.",1412.3232v2
+2014-12-16,High order cumulants of the azimuthal anisotropy in the dilute-dense limit: Connected graphs,"We analytically compute higher order cumulants of the azimuthal anisotropy,
+$c_2\{2m\}$, and corresponding $v_2\{2m\}$ at high transverse momentum in the
+dilute-dense limit. The dense target is considered in the framework of the
+McLerran-Venugopolan model. The absolute values of the harmonics $v_2\{2m\}$ of
+the azimuthal anisotropy are approximately equal, $|v_2\{2m\}| \approx
+|v_2\{2m'\}| $, for large $m$ and $m'$. However, the harmonics with order
+$2m=4n$ are complex. We argue that this is a generic property of connected
+graphs, which remains true in the dense-dense limit.",1412.5191v2
+2014-12-22,Surface sensitivity of the spin Seebeck effect,"We have investigated the influence of the interface quality on the spin
+Seebeck effect (SSE) of the bilayer system yttrium iron garnet (YIG) - platinum
+(Pt). The magnitude and shape of the SSE is strongly influenced by mechanical
+treatment of the YIG single crystal surface. We observe that the saturation
+magnetic field H_{sat} for the SSE signal increases from 55.3 mT to 72.8 mT
+with mechanical treatment. The change in the magnitude of H_{sat} can be
+attributed to the presence of a perpendicular magnetic anisotropy due to the
+treatment induced surface strain or shape anisotropy in the Pt/YIG system. Our
+results show that the SSE is a powerful tool to investigate magnetic anisotropy
+at the interface.",1412.7712v1
+2014-12-30,Reversible control of Co magnetism by voltage induced oxidation,"We demonstrate that magnetic properties of ultra-thin Co films adjacent to
+Gd2O3 gate oxides can be directly manipulated by voltage. The Co films can be
+reversibly changed from an optimally-oxidized state with a strong perpendicular
+magnetic anisotropy to a metallic state with an in-plane magnetic anisotropy,
+or to an oxidized state with nearly zero magnetization, depending on the
+polarity and time duration of the applied electric fields. Consequently, an
+unprecedentedly large change of magnetic anisotropy energy up to 0.73 erg/cm2
+has been realized in a nonvolatile manner using gate voltages of only a few
+volts. These results open a new route to achieve ultra-low energy magnetization
+manipulation in spintronic devices.",1412.8668v1
+2015-01-18,Physics of the cosmic microwave background anisotropy,"Observations of the cosmic microwave background (CMB), especially of its
+frequency spectrum and its anisotropies, both in temperature and in
+polarization, have played a key role in the development of modern cosmology and
+our understanding of the very early universe. We review the underlying physics
+of the CMB and how the primordial temperature and polarization anisotropies
+were imprinted. Possibilities for distinguishing competing cosmological models
+are emphasized. The current status of CMB experiments and experimental
+techniques with an emphasis toward future observations, particularly in
+polarization, is reviewed. The physics of foreground emissions, especially of
+polarized dust, is discussed in detail, since this area is likely to become
+crucial for measurements of the B modes of the CMB polarization at ever greater
+sensitivity.",1501.04288v1
+2015-02-19,Anisotropic parton escape is the dominant source of azimuthal anisotropy in transport models,"We trace the development of elliptic anisotropy ($v_2$) via parton-parton
+collision history in two transport models. The parton $v_2$ is studied as a
+function of the number of collisions of each parton in Au+Au and $d$+Au
+collisions at $\sqrt{s_{_{\rm NN}}}=200$ GeV. It is found that the majority of
+$v_2$ comes from the anisotropic escape probability of partons, with no
+fundamental difference at low and high transverse momenta. The contribution to
+$v_2$ from hydrodynamic-type collective flow is found to be small. Only when
+the parton-parton cross-section is set unrealistically large does this
+contribution start to take over. Our findings challenge the current paradigm
+emerged from hydrodynamic comparisons to anisotropy data.",1502.05572v4
+2015-02-23,The Casimir force between parallel plates separated by anisotropic media,"The Casimir force between two parallel plates separated by anisotropic media
+is investigated. We theoretically calculate the Casimir force between two
+parallel plates when the interspace between the plates is filled with
+anisotropic media. Our result shows that the anisotropy of the material between
+the plates can significantly affect the Casimir force, especially the direction
+of the force. If ignoring the anisotropy of the in-between material makes the
+force to be repulsive (attractive), by contrast, taking the anisotropy into
+account may produce an extra attractive (repulsive) force. The physical
+explanation for this phenomenon is also discussed.",1502.06335v2
+2015-02-23,Anisotropic Friedel oscillations inside the domain wall,"The influence of the non-collinear magnetic configuration on Friedel is
+investigated theoretically. Specifically the influence of the magnetic
+configuration on the induced electric charge in a N\'{e}el type domain wall
+(DW) has been obtained. The well-known Levy and Zhang eigenstates for a linear
+DW have been employed. Then the dielectric function of this magnetic system has
+been obtained within the random phase approximation. Results of the current
+work demonstrated that magnetic configuration of the system manifests itself in
+the electric properties such as induced charge distribution. Meanwhile the
+anisotropy of the induced charge distribution in the real space provides a
+measurable way for the determination of the DW orientation. In addition
+anisotropy of the dielectric function in k-space arises as a result of the
+anisotropy of the magnetic configuration. Therefore the orientation of the
+magnetic DW could also be captured by full optical measurements.",1502.06421v1
+2015-03-09,Quantized electronic fine structure with large anisotropy in ferromagnetic Fe films,"We report on the spectroscopic observation of a quantized electronic fine
+structure near the Fermi energy in thin Fe films grown on W(110). The quantum
+well states are detected down to binding energies of $\sim$10 meV by
+angle-resolved photoelectron spectroscopy. The band dispersion of these states
+is found to feature a pronounced anisotropy within the surface plane: It is
+free-electron like along the $\bar{\Gamma \rm{H}}$-direction while it becomes
+heavy along $\bar{\Gamma \rm{N}}$. Density functional theory calculations
+identify the observed states to have both majority and minority spin character
+and indicate that the large anisotropy can be dependent on the number of
+Fe-layers and coupling to the substrate.",1503.02440v1
+2015-03-12,Anisotropic particle production and azimuthal correlations in high-energy pA collisions,"We summarize some recent ideas relating to anisotropic particle production in
+high-energy collisions. Anisotropic gluon distributions lead to anisotropies of
+the single-particle azimuthal distribution and hence to disconnected
+contributions to multi-particle cumulants. When these dominate, the
+four-particle elliptic anisotropy $c_2\{4\}$ changes sign. On the other hand,
+connected diagrams for $m$-particle cumulants are found to quickly saturate
+with increasing $m$, a ``coherence'' quite unlike conventional ``non-flow''
+contributions such as decays. Finally, we perform a first exploratory
+phenomenological analysis in order to estimate the amplitude ${\cal A}$ of the
+$\cos(2\varphi)$ anisotropy of the gluon distribution at small $x$, and we
+provide a qualitative prediction for the elliptic asymmetry from three-particle
+correlations, $c_2\{3\}$.",1503.03897v1
+2015-03-31,Imprint of Inhomogeneous and Anisotropic Primordial Power Spectrum on CMB Polarization,"We consider an inhomogeneous model and independently an anisotropic model of
+primordial power spectrum in order to describe the observed hemispherical
+anisotropy in Cosmic Microwave Background Radiation. This anisotropy can be
+parametrized in terms of the dipole modulation model of the temperature field.
+Both the models lead to correlations between spherical harmonic coefficients
+corresponding to multipoles, l and l \pm 1. We obtain the model parameters by
+making a fit to TT correlations in CMBR data. Using these parameters we predict
+the signature of our models for correlations among different multipoles for the
+case of the TE and EE modes. These predictions can be used to test whether the
+observed hemispherical anisotropy can be correctly described in terms of a
+primordial power spectrum. Furthermore these may also allow us to distinguish
+between an inhomogeneous and an anisotropic model.",1503.08997v2
+2015-04-01,Impact of the modulation doping layer on the ν=5/2 anisotropy,"We have carried out a systematic study of the tilted magnetic field induced
+anisotropy at the Landau level filling factor \nu=5/2 in a series of high
+quality GaAs quantum wells, where the setback distance (d) between the
+modulation doping layer and the GaAs quantum well is varied from 33 to 164 nm.
+We have observed that in the sample of the smallest d electronic transport is
+anisotropic when the in-plane magnetic field (B_{ip}) is parallel to the [1-10]
+crystallographic direction, but remains more or less isotropic when B_{ip} //
+[110]. In contrast, in the sample of largest d, electronic transport is
+anisotropic in both crystallographic directions. Our results clearly show that
+the modulation doping layer plays an important role in the tilted field induced
+\nu=5/2 anisotropy.",1504.00338v1
+2015-04-17,"Ab initio calculations of the structural, electronic and elastic properties of the MZN2 (M=Be, Mg; Z=C, Si) chalcopyrite semiconductors","Four ternary semiconductors with the chalcopyrite structure (BeCN2, BeSiN2,
+MgCN2, and MgSiN2) were studied using the first principles methods. The
+structural, electronic, optical and elastic properties were calculated. All
+these materials were found to be the indirect band gap semiconductors, with the
+calculated band gaps in the range from 3.46 eV to 3.88 eV. Comparison of the
+degree of covalency/ionicity of the chemical bonds in these compounds was
+performed. Anisotropy of the optical properties of these tetragonal crystals
+was demonstrated by calculating the real and imaginary parts of the dielectric
+function {\epsilon}. Anisotropy of the elastic properties of these materials
+was analyzed by plotting the three-dimensional dependences of the Young moduli
+and their two-dimensional cross-sections. It was also shown (at least,
+qualitatively) that there exists a correlation between the optical and elastic
+anisotropy: the most optically anisotropic MgSiN2 is also most elastically
+anisotropic material in the considered group. High hardness (bulk moduli up to
+300 GPa) together with large band gaps may lead to new potential applications
+of these compounds.",1504.04440v1
+2015-04-26,Speed of field driven domain walls in nanowires with large transverse magnetic anisotropy,"Recent analytical and numerical work on field driven domain wall propagation
+in nanowires has shown that for large transverse anisotropy and sufficiently
+large applied fields the Walker profile becomes unstable before the breakdown
+field, giving way to a slower stationary domain wall. We perform an asymptotic
+expansion of the Landau Lifshitz Gilbert equation for large transverse magnetic
+anisotropy and show that the asymptotic dynamics reproduces this behavior. At
+low applied field the speed increases linearly with the field and the profile
+is the classic Landau profile. Beyond a critical value of the applied field the
+domain wall slows down. The appearance of a slower domain wall profile in the
+asymptotic dynamics is due to a transition from a pushed to a pulled front of a
+reaction diffusion equation.",1504.06865v1
+2015-05-11,Effects of anisotropy in simple lattice geometries on many-body properties of ultracold fermions in optical lattices,"We study the effects of anisotropic hopping amplitudes on quantum phases of
+ultracold fermions in optical lattices described by the repulsive Fermi-Hubbard
+model. In particular, using dynamical mean-field theory (DMFT) we investigate
+the dimensional crossover between the isotropic square and the isotropic cubic
+lattice. We analyze the phase transition from the antiferromagnetic to the
+paramagnetic state and observe a significant change in the critical
+temperature: Depending on the interaction strength, the anisotropy can lead to
+both a suppression or increase. We also investigate the localization properties
+of the system, such as the compressibility and double occupancy. Using the
+local density approximation in combination with DMFT we conclude that density
+profiles can be used to detect the mentioned anisotropy-driven transitions.",1505.02733v2
+2015-05-14,Sensitivity of full-sky experiments to large scale cosmic ray anisotropies,"The two main advantages of space-based observation of extreme energy
+($\gtrsim5\times10^{19}$ eV) cosmic rays (EECRs) over ground based
+observatories are the increased field of view and the full-sky coverage with
+nearly uniform systematics across the entire sky. The former guarantees
+increased statistics, whereas the latter enables a clean partitioning of the
+sky into spherical harmonics. The discovery of anisotropies would help to
+identify the long sought origin of EECRs. We begin an investigation of the
+reach of a full-sky space-based experiment such as EUSO to detect anisotropies
+in the extreme-energy cosmic-ray sky compared to ground based partial-sky
+experiments such as the Pierre Auger Observatory and Telescope Array. The
+technique is explained here, and simulations for a Universe with just two
+nonzero multipoles, monopole plus either dipole or quadrupole, are presented.
+These simulations quantify the advantages of space-based, all-sky coverage.",1505.03922v1
+2015-05-15,Manifestation of proton structure in the initial-state anisotropies in high-energy proton-proton collisions,"Ridge-like correlations in high-energy proton-proton collisions reported by
+the CMS collaboration suggest a collective flow that resembles the one in
+heavy-ion collisions. If the hydrodynamic description is valid then the effect
+results from the initial anisotropy of the colliding matter which depends on
+the structure of protons. Following recent theoretical developments, we propose
+several phenomenological models of the proton structure and calculate the
+anisotropy coefficients using the Monte Carlo Glauber model. Our estimates
+suggest that the event multiplicity dependence allows one to discriminate
+between different proton models.",1505.04155v4
+2015-05-24,Gamma-ray bounds from EAS detectors and heavy decaying dark matter constraints,"The very high energy Galactic $\gamma$-ray sky is partially opaque in the
+($0.1-10$) PeV energy range. In the light of the recently detected high energy
+neutrino flux by IceCube, a comparable very high energy $\gamma$-ray flux is
+expected in any scenario with a sizable Galactic contribution to the neutrino
+flux. Here we elaborate on the peculiar energy and anisotropy features imposed
+upon these very high energy $\gamma$-rays by the absorption on the cosmic
+microwave background photons and Galactic interstellar light. As a notable
+application of our considerations, we study the prospects of probing the
+PeV-scale decaying DM scenario, proposed as a possible source of IceCube
+neutrinos, by extensive air shower (EAS) cosmic ray experiments. In particular,
+we show that anisotropy measurements at EAS experiments are already sensitive
+to $\tau_{\rm DM}\sim {\cal O}(10^{27})$~s and future measurements, using
+better gamma/hadron separation, can improve the limit significantly.",1505.06486v2
+2015-05-26,Direction dependent thermal conductivity of monolayer phosphorene: parameterization of Stillinger-Weber potential and molecular dynamics study,"A Stillinger-Weber interatomic potential is parameterized for phosphorene. It
+well reproduces the crystal structure, cohesive energy and phonon dispersion
+predicted by first-principles calculations. The thermal conductivity of
+phosphorene is further explored by equilibrium molecular dynamics simulations
+adopting the optimal set of potential parameters. At room temperature, the
+intrinsic thermal conductivities along zigzag and armchair directions are about
+152.7 and 33.0 W/mK, respectively, with a large anisotropy ratio of five. The
+remarkably directional dependence of thermal conductivity in phosphorene,
+consistent with previous reports, is mainly due to the strong anisotropy of
+phonon group velocities, and weak anisotropy of phonon lifetimes as revealed by
+lattice dynamics calculations. Moreover, the effective phonon mean free paths
+at zigzag and armchair directions are about 141.4 and 43.4nm, respectively.",1505.06871v1
+2015-05-26,"Tunable electronic anisotropy in single-crystal A2Cr3As3 (A = K, Rb) quasi-one-dimensional superconductors","Single crystals of A2Cr3As3 (A = K, Rb) were successfully grown using a
+self-flux method and studied via structural, transport and thermodynamic
+measurement techniques. The superconducting state properties between the two
+species are similar, with critical temperatures of 6.1 K and 4.8 K in K2Cr3As3
+and Rb2Cr3As3, respectively. However, the emergence of a strong normal state
+electronic anisotropy in Rb2Cr3As3 suggests a unique electronic tuning
+parameter is coupled to the inter-chain spacing in the A2Cr3As3 structure,
+which increases with alkali metal ionic size while the one-dimensional
+[(Cr3As3)^{2-}]_{\infty} chain structure itself remains essentially unchanged.
+Together with dramatic enhancements in both conductivity and magnetoresistance
+(MR), the appearance of a strong anisotropy in the MR of Rb2Cr3As3 is
+consistent with the proposed quasi-one-dimensional character of band structure
+and its evolution with alkali metal species in this new family of
+superconductors.",1505.07051v2
+2015-06-02,Structure and Dynamics of Poly(methacrylic acid) and Its Interpolymer Complex Probed by Covalently Bound Rhodamine-123,"The dynamics and structural characteristics of polymethacrylic acid bound
+rhodamine-123 (PMAAR123) and its interpolymer complex with
+poly(vinylpyrrolidone) were investigated using single molecular fluorescence
+studies. The time resolved fluorescence anisotropy decay of PMAA-R123 at
+different pH exhibits an associated anisotropy decay behavior characteristic of
+two different environments experienced by the fluorophore and decays with one
+shorter and another longer lifetime components. The anisotropy decay retains
+normal bi-exponential behavior under neutral pH. Fluorescence correlation
+spectroscopic investigation reveals that the attached fluorophore undergoes
+hydrolysis under basic condition which results in the release of the
+fluorophore from the polymer backbone. Shrinkage in the hydrodynamic radius of
+PMAA is observed on addition of the complementary polymer PVP which is
+attributed to the formation compact solubilized nanoparticle like aggregates.
+The size of particle further decreases on the addition of NaCl. The detailed
+results show that these complexes have potential for use as drug-delivery
+system under physiological conditions.",1506.01044v2
+2015-06-18,Investigation of the Magnetic Model in Multiferroic NdFe$_{3}$(BO$_{3}$)$_{4}$ by Inelastic Neutron Scattering,"We performed inelastic neutron scattering measurements on single crystals of
+NdFe$_{3}$($^{11}$BO$_{3}$)$_{4}$ to explore the magnetic excitations, to
+establish the underlying Hamiltonian, and to reveal the detailed nature of
+hybridization between the 4$f$ and 3$d$ magnetism. The observed spectra
+exhibiting a couple of key features, i.e., anti-crossing of Nd- and
+Fe-excitations and anisotropy gap at the antiferromagnetic zone center, are
+explained by the magnetic model including spin interaction in the framework of
+weakly-coupled Fe$^{3+}$ chains, interaction between the Fe$^{3+}$ and
+Nd$^{3+}$ moments, and single-ion anisotropy derived from Nd$^{3+}$ crystal
+field. The combination of the measurements and calculations reveals that the
+hybridization between 4$f$ and 3$d$ magnetism propagates the local magnetic
+anisotropy of the Nd$^{3+}$ ion to the Fe$^{3+}$ network, resulting in the bulk
+structure of multiferroics.",1506.05569v2
+2015-06-21,Quantum Phase Transition and Protected Ideal Transport in a Kondo Chain,"We study the low energy physics of a Kondo chain where electrons from a
+one-dimensional band interact with magnetic moments via an anisotropic exchange
+interaction. It is demonstrated that the anisotropy gives rise to two different
+phases which are separated by a quantum phase transition. In the phase with
+easy plane anisotropy, Z$_2$ symmetry between sectors with different helicity
+of the electrons is broken. As a result, localization effects are suppressed
+and the dc transport acquires (partial) symmetry protection. This effect is
+similar to the protection of the edge transport in time-reversal invariant
+topological insulators. The phase with easy axis anisotropy corresponds to the
+Tomonaga-Luttinger liquid with a pronounced spin-charge separation. The slow
+charge density wave modes have no protection against localizatioin.",1506.06368v2
+2015-06-22,Event shape sorting,"We propose a novel method for sorting events of multiparticle production
+according to the azimuthal anisotropy of their momentum distribution. Although
+the method is quite general, we advocate its use in analysis of
+ultra-relativistic heavy-ion collisions where large number of hadrons is
+produced. The advantage of our method is that it can automatically sort out
+samples of events with histograms that indicate similar distributions of
+hadrons. It takes into account the whole measured histograms with all orders of
+anisotropy instead of a specific observable (e.g. $v_2$, $v_3$, $q_2$). It can
+be used for more exclusive experimental studies of flow anisotropies which are
+then more easily compared to theoretical calculations. It may also be useful in
+the construction of mixed-events background for correlation studies as it
+allows to select events with similar momentum distribution.",1506.06776v2
+2015-06-25,Impact of momentum-space anisotropy on heavy quark dynamics in a QGP medium,"Momentum space anisotropy present in the quark and gluon distribution
+functions in relativistic heavy ion collisions induces Chromo-Weibel
+instability in the hot QCD medium created therein. The impact of the
+Chromo-Weibel instability on the dynamics of a heavy-quark (HQ) traversing in
+the QGP medium is investigated within the framework of kinetic theory by
+studying the momentum and temperature behavior of HQ drag and diffusion
+coefficients. The physics of anisotropy is captured in an effective Vlasov term
+in the transport equation. The effects of the instability are handled by making
+a relation with the phenomenologically known jet quenching parameter in RHIC
+and LHC. Interestingly, the presence of instability significantly affect the
+temperature and momentum dependences of the HQ drag and diffusion coefficients.
+These results may have appreciable impact on the experimental observables such
+as, the nuclear suppression factor, $R_{AA}(p_T)$, and the elliptic flow,
+$v_2(p_T)$, of heavy mesons in heavy ion collisions at RHIC and LHC energies
+which is a matter of future investigation.",1506.07805v3
+2015-07-06,Delta chain with anisotropic ferromagnetic and antiferromagnetic interactions,"We consider analytically and numerically an anisotropic spin-$\frac{1}{2}$
+delta-chain (sawtooth chain) with nearest-neighbor ferromagnetic and
+next-nearest-neighbor antiferromagnetic interactions. For certain values of the
+interactions a lowest one-particle band becomes flat and there is a class of
+localized-magnon eigenstates which form a ground state with a macroscopic
+degeneracy. In this case the model depends on a single parameter which can be
+chosen as the anisotropy of the exchange interactions. When this parameter
+changes from zero to infinity the model interpolates between the
+one-dimensional isotropic ferromagnet and the frustrated Ising model on the
+delta-chain. It is shown that the low-temperature thermodynamic properties in
+these limiting cases are governed by the specific structure of the excitation
+spectrum. In particular, the specific heat has one or infinite number of
+low-temperature maxima for the small or the large anisotropy parameter,
+correspondingly. Numerical calculations of finite chains demonstrate that this
+behavior is generic for definite values of the anisotropy parameter.",1507.01389v1
+2015-07-07,Anisotropy of iron-platinum-arsenide Ca10(PtnAs8)(Fe2-xPtxAs2)5 single crystals,"The upper critical field Hc2 anisotropy of Ca10(PtnAs8)(Fe2-xPtxAs2)5 (n = 3,
+4) single crystals with long FeAs interlayer distance (d) was studied by
+angular dependent resistivity measurements. A scaling of the angular dependent
+resistivity was realized for both single crystals using the anisotropic
+Ginzburg-Landau (AGL) approach with an appropriate anisotropy parameter
+{\gamma}. The AGL scaling parameter {\gamma} increases with decreasing
+temperature and reaches a value of about 10 at 0.8Tc for both single crystals.
+These values are much larger than those of other iron-based superconductors
+(FeSCs). Remarkably, the values of {\gamma}2 show an almost linear increase
+with the FeAs/FeSe interlayer distance d for FeSCs. Compared to cuprates, FeSCs
+are less anisotropic, indicating that two dimensionality of the
+superconductivity is intrinsically weak.",1507.01987v1
+2015-07-20,Electronic nematic correlations in the stress free tetragonal state of BaFe$_{2-x}$Ni$_{x}$As$_{2}$,"We use transport and neutron scattering to study electronic, structural, and
+magnetic properties of the electron-doped BaFe$_{2-x}$Ni$_x$As$_2$ iron
+pnictides in the external stress free detwinned state. Using a specially
+designed in-situ mechanical detwinning device, we demonstrate that the in-plane
+resistivity anisotropy observed in the uniaxial strained tetragonal state of
+BaFe$_{2-x}$Ni$_x$As$_2$ below a temperature $T^\ast$, previously identified as
+a signature of the electronic nematic phase, is also present in the stress free
+tetragonal phase below $T^{\ast\ast}$ ($<T^\ast$). By carrying out neutron
+scattering measurements on BaFe$_2$As$_2$ and BaFe$_{1.97}$Ni$_{0.03}$As$_2$,
+we argue that the resistivity anisotropy in the stress free tetragonal state of
+iron pnictides arises from the magnetoelastic coupling associated with
+antiferromagnetic order. These results thus indicate that the local lattice
+distortion and nematic spin correlations are responsible for the resistivity
+anisotropy in the tetragonal state of iron pnictides.",1507.05423v1
+2015-07-23,Photon production from a non-equilibrium quark-gluon plasma,"We calculate leading-order medium photon yields from a quark-gluon plasma
+using (3+1)-dimensional anisotropic hydrodynamics. Non-equilibrium corrections
+to the photon rate are taken into account using a self-consistent modification
+of the particle distribution functions and the corresponding anisotropic
+hard-loop fermionic self-energies. We present predictions for the high-energy
+photon spectrum and photon elliptic flow as a function of transverse momentum,
+shear viscosity, and initial momentum-space anisotropy. Our findings indicate
+that high-energy photon production is sensitive to the assumed level of initial
+momentum-space anisotropy of the quark-gluon plasma. As a result, it may be
+possible to experimentally constrain the early-time momentum-space anisotropy
+of the quark-gluon plasma generated in relativistic heavy-ion collisions using
+high-energy photon yields.",1507.06605v3
+2015-08-05,Anisotropy of the acoustooptic figure of merit for LiNbO3 crystals. Isotropic diffraction,"We have developed the approach for analyzing of anisotropy of acoustooptic
+figure of merit (AOFM) for lithium niobate crystals in the case of isotropic
+acoustooptic (AO) diffraction. The working relations for the effective
+elastooptic coefficients and the AOFM have been derived. We have found that,
+under the conditions of isotropic AO diffraction, the maximum AOFM value for
+LiNbO3 is equal tp 11.62x10-15s3/kg. It is peculiar for the geometry of AO
+interaction of the shear acoustic wave propagating in the YZ plane (the
+velocity 3994 m/s) with the optical wave polarized in the same plane. We have
+demonstrated that the maximum AOFM values are achieved mainly due to essential
+anisotropy and high values of the elastooptic coefficients of LiNbO3.",1508.01075v1
+2015-08-10,Standardized compliance matrixes for general anisotropic materials and a simple measure of anisotropy degree based on shear-extension coupling coefficient,"The compliance matrix for a general anisotropic material is usually expressed
+in an arbitrarily chosen coordinate system, which brings some confusion or
+inconvenience in identifying independent elastic material constants and
+comparing elastic properties between different materials. In this paper, a
+unique stiffest orientation based standardized (STF-OS) compliance matrix is
+established, and 18 independent elastic material constants are clearly shown.
+During the searching process for stiffest orientation, it is interesting to
+find from our theoretical analysis and an example that a material with
+isotropic tensile stiffness does not definitely possess isotropic elasticity.
+Therefore the ratio between the maximum and minimum tensile stiffnesses is not
+a correct measure of anisotropy degree. Alternatively, a simple and correct
+measure of anisotropy degree based on the maximum shear-extension coupling
+coefficient in all orientations is proposed.",1508.02105v1
+2015-08-10,Strain-Induced Magnetic Anisotropy in Epitaxial Thin Films of the Spinel CoCr$_2$O$_4$,"We show that the magnetic anisotropy in spinel-structure CoCr$_2$O$_4$ thin
+films exhibits a strain dependence in which compressive strain induces an
+out-of-plane magnetic easy axis and tensile strain an in-plane easy axis,
+exactly opposite to the behavior reported for the related compound
+CoFe$_2$O$_4$. We use density functional theory calculations within the LSDA+U
+approximation to reproduce and explain the observed behavior. Using
+second-order perturbation theory, we analyse the anisotropy tensor of the
+Co$^{2+}$ ions in both octahedral and tetrahedral coordination, allowing us to
+extend our results to spinels with general arrangements of Co$^{2+}$ ions.",1508.02165v1
+2015-08-13,Survival rate of initial azimuthal anisotropy in a multi-phase transport model,"We investigate the survival rate of an initial momentum anisotropy
+(${v}_2^{ini}$), not spatial anisotropy, to the final state in a multi-phase
+transport (AMPT) model in Au+Au collisions at $\sqrt{s_{NN}}$=200~GeV. It is
+found that both the final-state parton and charged hadron $v_2$ show a linear
+dependence versus $v_2^{ini}\{\rm PP\}$ with respect to the participant plane
+(PP). It is found that the slope of this linear dependence (referred to as the
+survive rate) increases with transverse momentum ($p_T$), reaching~$\sim$100\%
+at $p_T$$\sim$2.5 GeV/c for both parton and charged hadron. The survival rate
+decreases with collision centrality and energy, indicating decreasing survival
+rate with increasing interactions. It is further found that a $v_2^{ini}\{\rm
+Rnd\}$ with respect to a random direction does not survive in $v_2\{\rm PP\}$
+but in the two-particle cumulant $v_2\{2\}$. The dependence of $v_2\{2\}$ on
+$v_2^{ini}\{\rm Rnd\}$ is quadratic rather than linear.",1508.03215v2
+2015-09-09,Current helicity and magnetic field anisotropy in solar active regions,"The electric current helicity density $\displaystyle
+\chi=\langle\epsilon_{ijk}b_i\frac{\partial b_k}{\partial x_j}\rangle$ contains
+six terms, where $b_i$ are components of the magnetic field. Due to the
+observational limitations, only four of the above six terms can be inferred
+from solar photospheric vector magnetograms. By comparing the results for
+simulation we distinguished the statistical difference of above six terms for
+isotropic and anisotropic cases. We estimated the relative degree of anisotropy
+for three typical active regions and found that it is of order 0.8 which means
+the assumption of local isotropy for the observable current helicity density
+terms is generally not satisfied for solar active regions. Upon studies of the
+statistical properties of the anisotropy of magnetic field of solar active
+regions with latitudes and with evolution in the solar cycle, we conclude that
+the consistency of that assumption of local homogeneity and isotropy requires
+further analysis in the light of our findings.",1509.02652v1
+2015-09-14,Photon and dilepton production from a non-equilibrium quark-gluon plasma,"We calculate leading-order medium photon and dilepton yields from a
+quark-gluon plasma using (3+1)-dimensional anisotropic hydrodynamics. In the
+case of dileptons, at leading-order it is sufficient to take into account
+non-equilibrium corrections to the rate through the use of anisotropic
+distribution functions. In the case of photons, non-equilibrium corrections to
+the rate are taken into account using a self-consistent modification of the
+distribution functions and the corresponding anisotropic hard-loop quark
+self-energies. We present predictions for the high-energy photon and dilepton
+spectrum and the photon elliptic flow as a function of invariant mass,
+transverse momentum, shear viscosity, and initial momentum-space anisotropy.
+Our findings indicate that both high-energy photon and dilepton production are
+sensitive to the assumed level of initial momentum-space anisotropy of the
+quark-gluon plasma. In addition, we find that the photon elliptic flow depends
+on the initial momentum-space anisotropy.",1509.04249v1
+2015-09-24,Skyrmions in Chiral Magnets with Rashba and Dresselhaus Spin-Orbit Coupling,"Skyrmions are topological spin textures of interest for fundamental science
+and applications. Previous theoretical studies have focused on systems with
+broken bulk inversion symmetry, where skyrmions are stabilized by easy-axis
+anisotropy. We investigate here systems that break surface inversion symmetry,
+in addition to possible broken bulk inversion. This leads to two distinct
+Dzyaloshinskii-Moriya (DM) terms with strengths $D_\perp$, arising from Rashba
+spin-orbit coupling (SOC), and $D_\parallel$ from Dresselhaus SOC. We show that
+skyrmions become progressively more stable with increasing
+$D_\perp/D_\parallel$, extending into the regime of easy-plane anisotropy. We
+find that the spin texture and topological charge density of skyrmions develops
+nontrivial spatial structure, with quantized topological charge in a unit cell
+given by a Chern number. Our results give a design principle for tuning Rashba
+SOC and magnetic anisotropy to stabilize skyrmions in thin films, surfaces,
+interfaces and bulk magnetic materials that break mirror symmetry.",1509.07508v2
+2015-09-29,Coherent control of group index and magneto-optical anisotropy in a multilevel atomic vapor,"We study electromagnetically induced transparency (EIT) in a heated potassium
+vapor cell, using a simple optical setup with a single free-running diode laser
+and an acousto-optic modulator. Despite the fact that the Doppler width is
+comparable to the ground state hyperfine splitting, transparency windows with
+deeply sub-natural line widths and large group indices are obtained. A
+longitudinal magnetic field is used to split the EIT feature and induce
+magnetooptical anisotropy. Using the beat note between co-propagating coupling
+and probe beams, we perform a heterodyne measurement of the circular dichroism
+(and therefore birefringence) of the EIT medium. The observed spectra reveal
+that lin-par-lin polarizations lead to greater anisotropy than lin-perp-lin. A
+simplified analytical model encompassing sixteen Zeeman states and eighteen
+\Lamda\ subsytems reproduces the experimental observations.",1509.08776v4
+2015-09-30,The origin of anisotropy and high density of states in the electronic structure of Cr$_2$GeC by means of polarized soft X-ray spectroscopy and ab initio calculations,"The anisotropy in the electronic structure of the inherently nanolaminated
+ternary phase Cr$_{2}$GeC is investigated by bulk-sensitive and element
+selective soft x-ray absorption/emission spectroscopy. The angle-resolved
+absorption/emission measurements reveal differences between the in-plane and
+out-of-plane bonding at the (0001) interfaces of Cr$_{2}$GeC. The Cr $L_{2,3}$,
+C $K$, and Ge $M_{1}$, $M_{2,3}$ emission spectra are interpreted with
+first-principles density-functional theory (DFT) including core-to-valence
+dipole transition matrix elements. For the Ge $4s$ states, the x-ray emission
+measurements reveal two orders of magnitude higher intensity at the Fermi level
+than DFT within the General Gradient Approximation (GGA) predicts. We provide
+direct evidence of anisotropy in the electronic structure and the orbital
+occupation that should affect the thermal expansion coefficient and transport
+properties. As shown in this work, hybridization and redistribution of
+intensity from the shallow $3d$ core levels to the $4s$ valence band explain
+the large Ge density of states at the Fermi level.",1509.09190v1
+2015-10-03,Engineering spin-orbit torque in Co/Pt multilayers with perpendicular magnetic anisotropy,"To address thermal stability issues for spintronic devices with a reduced
+size, we investigate spin-orbit torque in Co/Pt multilayers with strong
+perpendicular magnetic anisotropy. Note that the spin-orbit torque arises from
+the global imbalance of the spin currents from the top and bottom interfaces
+for each Co layer. By inserting Ta or Cu layers to strengthen the top-down
+asymmetry, the spin-orbit torque efficiency can be greatly modified without
+compromised perpendicular magnetic anisotropy. Above all, the efficiency builds
+up as the number of layers increases, realizing robust thermal stability and
+high spin-orbit-torque efficiency simultaneously in the multilayers structure.",1510.00836v1
+2015-10-05,On the upper limits for dipole anisotropies in cosmic-ray positrons,"The excess of cosmic-ray positrons in the energy range from 10 GeV to few
+hundred GeV reported by PAMELA and AMS experiments is not consistent with a
+pure secondary origin and requires the introduction of a source term. The
+presence of anisotropies in the positron arrival directions would be a
+distinctive signature of their origin. Current measurements are consistent with
+isotropy and limits to a dipole anisotropy have been established. In this note,
+we review the mathematical basis of this analysis and provide a general bound
+to the dipole upper limits achievable from a given sample of events. The
+published experimental limits are confronted with this bound.",1510.01221v1
+2015-10-06,Unveiling the Origin of the Basal-plane Antiferromagnetism in the Jeff=1/2 Mott Insulator Ba2IrO4: A Density Functional and Model Hamiltonian Study,"Based on the density functional theory and our new model Hamiltonian, we have
+studied the basal-plane antiferromagnetism in the novel Jeff=1/2 Mott insulator
+Ba2IrO4. By comparing the magnetic properties of the bulk Ba2IrO4 with those of
+the single-layer Ba2IrO4, we demonstrate unambiguously that the basal-plane
+antiferromagnetism is caused by the intralyer magnetic interactions rather than
+by the previously proposed interlayer ones. In order to reveal the origin of
+the basal-plane antiferromagnetism, we propose a new model Hamiltonian by
+adding the single ion anisotropy and pseudo-quadrupole interactions into the
+general bilinear pseudo-spin Hamiltonian. The obtained magnetic interaction
+parameters indicate that the single ion anisotropy and pseudo-quadrupole
+interactions are unexpectedly strong. Systematical Monte Carlo simulations
+demonstrate that the basal-plane antiferromagnetism is caused by the isotropic
+Heisenberg, bond-dependent Kitaev and pseudo-quadrupole interactions. Our
+results show for the first time that the single ion anisotropy and
+pseudo-quadrupole interaction can play significant roles in establishing the
+exotic magnetism in the Jeff=1/2 Mott insulator.",1510.01451v1
+2015-10-08,Explaining TeV Cosmic-Ray Anisotropies with Non-Diffusive Cosmic-Ray Propagation,"Constraining the behavior of cosmic ray data observed at Earth requires a
+precise understanding of how the cosmic rays propagate in the interstellar
+medium. The interstellar medium is not homogeneous; although turbulent magnetic
+fields dominate over large scales, small coherent regions of magnetic field
+exist on scales relevant to particle propagation in the nearby Galaxy. Guided
+propagation through a coherent field is significantly different from random
+particle diffusion and could be the explanation of spatial anisotropies in the
+observed cosmic rays. We present a Monte Carlo code to propagate cosmic
+particle through realistic magnetic field structures. We discuss the details of
+the model as well as some preliminary studies which indicate that coherent
+magnetic structures are important effects in local cosmic-ray propagation,
+increasing the flux of cosmic rays by over two orders of magnitude at
+anisotropic locations on the sky. The features induced by coherent magnetic
+structure could be the cause of the observed TeV cosmic-ray anisotropy.",1510.02487v2
+2015-10-29,Indirect switching of vortex polarity through magnetic dynamic coupling,"Magnetic vortex cores exhibit a gyrotropic motion, and may reach a critical
+velocity, at which point they invert their z-component of the magnetization. We
+performed micromagnetic simulations to describe this vortex core polarity
+reversal in magnetic nanodisks presenting a perpendicular anisotropy. We found
+that the critical velocity decreases with increasing perpendicular anisotropy,
+therefore departing from a universal criterion, that relates this velocity only
+to the exchange stiffness of the material. This leads to a critical velocity
+inversely proportional to the vortex core radius. We have also shown that in a
+pair of interacting disks, it is possible to switch the core vortex polarity
+through a non-local excitation; exciting one disk by applying a rotating
+magnetic field, one is able to switch the polarity of a neighbor disk, with a
+larger perpendicular anisotropy.",1510.08783v1
+2015-10-30,Density of states in gapped superconductors with pairing-potential impurities,"We study the density of states in disordered s-wave superconductors with a
+small gap anisotropy. Disorder comes in the form of common nonmagnetic
+scatterers and pairing-potential impurities, which interact with electrons via
+an electric potential and a local distortion of the superconducting gap. A set
+of equations for the quasiclassical Green functions is derived and solved.
+Within one spin sector, pairing-potential impurities and weak spin-polarized
+magnetic impurities have essentially the same effect on the density of states.
+We show that if the gap is isotropic, an isolated impurity with suppressed
+pairing supports an infinite number of Andreev states. With growing impurity
+concentration, the energy-dependent density of states evolves from a sharp gap
+edge with an impurity band below it to a smeared BCS singularity in the
+so-called universal limit. If a gap anisotropy is present, the density of
+states becomes sensitive to ordinary potential disorder, and the existence of
+of Andreev states localized at pairing-potential impurities requires special
+conditions. An unusual feature related to the anisotropy is a nonmonotonic
+dependence of the gap edge smearing on impurity concentration.",1510.09172v1
+2015-11-13,Cosmic ray transport and anisotropies to high energies,"A model is introduced, in which the irregularity spectrum of the Galactic
+magnetic field beyond the dissipation length scale is first a Kolmogorov
+spectrum $k^{-5/3}$ at small scales $\lambda \, = \, 2 \pi/k$ with $k$ the
+wave-number, then a saturation spectrum $k^{-1}$, and finally a shock-dominated
+spectrum $k^{-2}$ mostly in the halo/wind outside the Cosmic Ray disk. In an
+isotropic approximation such a model is consistent with the Interstellar Medium
+(ISM) data. With this model we discuss the Galactic Cosmic Ray (GCR) spectrum,
+as well as the extragalactic Ultra High Energy Cosmic Rays (UHECRs), their
+chemical abundances and anisotropies. UHECRs may include a proton component
+from many radio galaxies integrated over vast distances, visible already below
+3 EeV.",1511.04229v1
+2015-11-23,Spin-orbit coupling controlled ground state in Sr$_2$ScOsO$_6$,"We report neutron scattering experiments which reveal a large spin gap in the
+magnetic excitation spectrum of weakly-monoclinic double perovskite Sr2ScOsO6.
+The spin gap is demonstrative of appreciable spin-orbit-induced anisotropy,
+despite nominally orbitally-quenched 5d3 Os5+ ions. The system is successfully
+modeled including nearest neighbor interactions in a Heisenberg Hamiltonian
+with exchange anisotropy. We find that the presence of the spin-orbit-induced
+anisotropy is essential for the realization of the type I antiferromagnetic
+ground state. This demonstrates that physics beyond the LS or JJ coupling
+limits plays an active role in determining the collective properties of 4d3 and
+5d3 systems, and that theoretical treatments must include spin-orbit coupling.",1511.07486v3
+2015-11-24,Magnetic domain walls in nanostrips of single-crystalline $\mathrm{Fe}_4\mathrm{N}(001)$ thin films with fourfold in-plane magnetic anisotropy,"We investigated head-to-head domain walls in nanostrips of epitaxial
+$\mathrm{Fe}_4\mathrm{N}(001)$ thin films, displaying a fourfold magnetic
+anisotropy. Magnetic force microscopy and micromagnetic simulations show that
+the domain walls have specific properties, compared to soft magnetic materials.
+In particular, strips aligned along a hard axis of magnetization are wrapped by
+partial flux-closure concertina domains below a critical width, while
+progressively transforming to zigzag walls for wider strips. Transverse walls
+are favored upon initial application of a magnetic field transverse to the
+strip, while transformation to a vortex walls is favored upon motion under a
+longitudinal magnetic field. In all cases the magnetization texture of such
+fourfold anisotropy domain walls exhibits narrow micro-domain walls, which may
+give rise to peculiar spin-transfer features.",1511.07520v1
+2015-12-02,Strain-activated structural anisotropy in BaFe2As2,"High-resolution single crystal neutron diffraction measurements are presented
+probing the magnetostructural response to uniaxial pressure in the iron
+pnictide parent system BaFe2As2. Scattering data reveal a strain-activated,
+anisotropic broadening of nuclear Bragg reflections, which increases upon
+cooling below the resolvable onset of global orthorhombicity. This anisotropy
+in lattice coherence continues to diverge until a lower temperature scale---the
+first-order onset of antiferromagnetism---is reached. Our data suggest that
+antiferromagnetism and strong magnetoelastic coupling drive the
+strain-activated lattice response in this material and that the development of
+anisotropic lattice coherence under strain is the physical origin for the
+anomalous nematic anisotropy in this compound.",1512.00782v2
+2015-12-07,Exact results for model wave functions of anisotropic composite fermions in the fractional quantum Hall effect,"The microscopic wave functions of the composite fermion theory can
+incorporate electron mass anisotropy by a trivial rescaling of the coordinates.
+These wave functions are very likely adiabatically connected to the actual wave
+functions of the anisotropic fractional quantum Hall states. We show in this
+article that they possess the nice property that their energies can be
+analytically related to the previously calculated energies for the isotropic
+states through a universal scale factor, thus allowing an estimation of several
+observables in the thermodynamic limit for all fractional quantum Hall states.
+The rather weak dependence of the scale factor on the anisotropy provides
+insight into why fractional quantum Hall effect and composite fermions are
+quite robust to electron mass anisotropy. We discuss how better, though still
+approximate, wave functions can be obtained by introducing a variational
+parameter, following Haldane [Phys. Rev. Lett. {\bf 107}, 116801 (2011)], but
+the resulting wave functions are not readily amenable to calculations. Our
+considerations are also applicable, with minimal modification, to the case
+where the dielectric function of the background material is anisotropic.",1512.01894v2
+2015-12-07,Origin of the DC and AC conductivity anisotropy in iron-based superconductors: scattering rate versus spectral weight effects,"To shed light on the mechanism responsible for the in-plane resistivity
+anisotropy in the nematic phase of the iron-based superconductors, we
+investigate the impact of spin fluctuations on the anisotropic AC conductivity.
+On the one hand, the scattering of electrons off magnetic fluctuations causes
+an anisotropic scattering rate. On the other hand, the accompanying Fermi
+velocity renormalization contributes to both the plasma frequency and the
+scattering rate in antagonistic ways, giving rise to anisotropies in these
+quantities that exactly cancel each other in the DC limit. As a result, the
+effective scattering rate changes its sign as function of temperature, but the
+DC conductivity retains the same sign, in agreement with recent experiments.",1512.02259v2
+2015-12-08,Atomistic Simulation of frictional anisotropy on quasicrystal approximant surfaces,"Park {\it et al.} have reported eight times greater atomic-scale friction in
+the periodic than in the quasiperiodic direction on the two-fold face of a
+decagonal Al-Ni-Co quasicrystal. We present results of molecular-dynamics
+simulations intended to elucidate mechanisms behind this giant frictional
+anisotropy. Simulations of a bare atomic-force-microscope tip on several model
+substrates and under a variety of conditions failed to reproduce experimental
+results. On the other hand, including the experimental passivation of the tip
+with chains of hexadecane thiol, we reproduce qualitatively the experimental
+anisotropy in friction, finding evidence for entrainment of the organic chains
+in surface furrows parallel to the periodic direction.",1512.02305v2
+2015-12-14,Magnetic critical properties and basal-plane anisotropy of Sr$_2$IrO$_4$,"The anisotropic magnetic properties of Sr$_2$IrO$_4$ are investigated, using
+longitudinal and torque magnetometry. The critical scaling across $T_c$ of the
+longitudinal magnetization is the one expected for the 2D XY universality
+class. Modeling the torque for a magnetic field in the basal-plane, and taking
+into account all in-plane and out-of-plane magnetic couplings, we derive the
+effective 4-fold anisotropy $K_4 \approx$ 1 10$^5$ erg mole$^{-1}$. Although
+larger than for the cuprates, it is found too small to account for a
+significant departure from the isotropic 2D XY model. The in-plane torque also
+allows us to put an upper bound for the anisotropy of a field-induced shift of
+the antiferromagnetic ordering temperature.",1512.04448v1
+2015-12-30,Cross-field transport and pitch-angle anisotropy of solar energetic particles in MHD turbulence,"Recent modelling of solar energetic particles (SEPs) propagation through the
+heliospheric turbulence, also discussed in this workshop, has investigated the
+role of the pitch-angle scattering and the perpendicular transport in spreading
+particles in heliolongitude, as shown by multi-spacecraft measurements (STEREO
+A/B, ACE, SOHO, etc.) at 1 AU in various energy ranges. In some events the
+first-order pitch-angle anisotropy of the particles distribution is
+not-negligible. We calculate the average perpendicular displacement due to the
+gradient/curvature drift in an inhomogeneous turbulence accounting for
+pitch-angle dependence for two MHD turbulence models: (a) 3-D isotropic, (b)
+anisotropic as conjectured by Goldreich-Sridhar. We find in both cases that the
+drift scales as $(1-\mu^2)^2$ with the cosine of pitch-angle $\mu$, in contrast
+with previous models for transport of SEPs. This result can impact the models
+of propagation of SEPs through the heliosphere.",1512.08973v1
+2016-01-05,Anisotropic parton escape is the dominant source of azimuthal anisotropy in transport models,"We trace the development of elliptic anisotropy (v2) via parton-parton
+collision history in two transport models. The parton v2 is studied as a
+function of the number of collisions of each parton in Au+Au and d+Au
+collisions at sNN =200 GeV. It is found that the majority of v2 comes from the
+anisotropic escape probability of partons, with no fundamental difference at
+low and high transverse momenta. The contribution to v2 from hydrodynamic-type
+collective flow is found to be small. Only when the parton-parton cross-section
+is set unrealistically large does this contribution start to take over. Our
+findings challenge the current paradigm emerged from hydrodynamic comparisons
+to anisotropy data.",1601.00878v2
+2016-01-10,"Interfacial Dzyaloshinskii-Moriya interaction, surface anisotropy energy,and spin pumping at spin orbit coupled Ir/Co interface","The interfacial Dzyaloshinskii-Moriya interaction (iDMI), surface anisotropy
+energy, and spin pumping at the Ir/Co interface are experimentally investigated
+by performing Brillouin light scattering. Contrary to previous reports, we
+suggest that the sign of the iDMI at the Ir/Co interface is the same as in the
+case of the Pt/Co interface. We also find that the magnitude of the iDMI energy
+density is relatively smaller than in the case of the Pt/Co interface, despite
+the large strong spin-orbit coupling (SOC) of Ir. The saturation magnetization
+and the perpendicular magnetic anisotropy (PMA) energy are significantly
+improved due to a strong SOC. Our findings suggest that an SOC in an Ir/Co
+system behaves in different ways for iDMI and PMA. Finally, we determine the
+spin pumping effect at the Ir/Co interface, and it increases the Gilbert
+damping constant from 0.012 to 0.024 for 1.5 nmthick Co.",1601.02210v3
+2016-01-12,Domain configurations in Co/Pd and L10-FePt nanowire arrays with perpendicular magnetic anisotropy,"Perpendicular magnetic anisotropy [Co/Pd]15 and L10-FePt nanowire arrays of
+period 63 nm with linewidths 38 nm and 27 nm and film thickness 27 nm and 20 nm
+respectively were fabricated using a self-assembled PS-b-PDMS diblock copolymer
+film as a lithographic mask. The wires are predicted to support Neel walls in
+the Co/Pd and Bloch walls in the FePt. Magnetostatic interactions from nearest
+neighbor nanowires promote a ground state configuration consisting of
+alternating up and down magnetization in adjacent wires. This was observed over
+~75% of the Co/Pd wires after ac-demagnetization but was less prevalent in the
+FePt because the ratio of interaction field to switching field was much
+smaller. Interactions also led to correlations in the domain wall positions in
+adjacent Co/Pd nanowires. The reversal process was characterized by nucleation
+of reverse domains, followed at higher fields by propagation of the domains
+along the nanowires. These narrow wires provide model system for exploring
+domain wall structure and dynamics in perpendicular anisotropy systems.",1601.02735v1
+2016-02-01,Higher order test of Lorentz invariance with an optical ring cavity,"We have developed an apparatus to search for the higher-order Lorentz
+violation in photons by measuring the resonant frequency difference between two
+counterpropagating directions of an asymmetric optical ring cavity. From the
+year-long data taken between 2012 and 2013, we found no evidence for the light
+speed anisotropy at the level of $\delta c/c \lesssim 10^{-15}$. Limits on the
+dipole components of the anisotropy are improved by more than an order of
+magnitude, and limits on the hexapole components are obtained for the first
+time. An overview of our apparatus and the data analysis in the framework of
+the spherical harmonics decomposition of anisotropy are presented. We also
+present the status of the recent upgrade of the apparatus.",1602.00391v1
+2016-02-03,Dynamic Error in Strain Induced Magnetization Reversal of Nanomagnets due to Incoherent Switching and Formation of Metastable States: A Size-dependent Study,"Modulation of stress anisotropy of magnetostrictive nanomagnets with strain
+offers an extremely energy-efficient method of magnetization reversal. The
+reversal process, however, is often incoherent and hence error-prone in the
+presence of thermal noise at room temperature. Occurrence of incoherent
+metastable states in the potential landscape of the nanomagnet can further
+exacerbate the error. Stochastic micromagnetic simulations at room temperature
+are used to understand and calculate energy dissipations and switching error
+probabilities in this important magnetization switching methodology. We find
+that these quantities have an intriguing dependence on nanomagnet size: small
+nanomagnets perform better owing to the fact that they are more resilient to
+the formation of metastable states and magnetization dynamics in them is more
+coherent. However, for a fixed stress anisotropy energy density, smaller
+nanomagnets will also have poorer resilience against thermal instability. Thus,
+the challenge in straintronics is to maximize the stress anisotropy energy
+density by developing materials and processes that yield the largest
+magnetostriction.",1602.01491v2
+2016-02-06,Testing the isotropy of the Hubble expansion,"We have used the Union2.1 SNIa compilation to search for possible Hubble
+expansion anisotropies, dividing the sky in 9 solid angles containing roughly
+the same number of SNIa, as well as in the two Galactic hemispheres. We
+identified only one sky region, containing 82 SNIa (~15% of total sample with
+$z>0.02$), that indeed appears to share a significantly different Hubble
+expansion than the rest of the sample. However, this behavior appears to be
+attributed to the joint ""erratic"" behavior of only three SNIa and not to an
+anisotropic expansion. We also find that the northern and southern galactic
+hemispheres have different cosmological parameter solutions but still not
+significant enough to assert the detection of a Hubble expansion anisotropy. We
+conclude that even a few outliers can have such an effect as to induce
+artificial indications of anisotropies, when the number of analysed SNIa is
+relatively small.",1602.02310v1
+2016-02-15,Decoherence wave in magnetic systems and creation of Néel antiferromagnetic state by measurement,"The interplay between the singlet ground state of the antiferromagnetic
+Heisenberg model and the experimentally measured N\'eel state of
+antiferromagnets is studied. To verify the hypothesis [M. I. Katsnelson et al.,
+Phys. Rev. B 63, 212404 (2001)] that the latter can be considered to be a
+result of local measurements destroying the entanglement of the quantum ground
+state, we have performed systematic simulations of the effects of von
+Neumannmeasurements for the case of a one-dimensional antiferromagnetic
+spin-1/2 system for various types and degrees of magnetic anisotropies. It is
+found that in the ground state, a magnetization measurement can create
+decoherence waves [M. I. Katsnelson et al. Phys. Rev. A 62, 022118 (2000)] in
+the magnetic sublattices, and that a symmetry breaking anisotropy does not lead
+to alignment of the spins in a particular direction. However, for an easy-axis
+anisotropy of the same order magnitude as the exchange constant, a measurement
+on the singlet ground state can create N\'eel-ordering in finite systems of
+experimentally accessible size.",1602.04703v1
+2016-02-20,Simultaneous Evidence for Pauli Paramagnetic Effects and Multiband Superconductivity in KFe$_2$As$_2$ by Small-Angle Neutron Scattering Studies of the Vortex Lattice,"We study the intrinsic anisotropy of the superconducting state in
+KFe$_2$As$_2$, using small-angle neutron scattering to image the vortex lattice
+as the applied magnetic field is rotated towards the FeAs crystalline planes.
+The anisotropy is found to be strongly field dependent, indicating multiband
+superconductivity. Furthermore, the high field anisotropy significantly exceeds
+that of the upper critical field, providing further support for Pauli limiting
+in KFe$_2$As$_2$ for field applied in the basal plane. The effect of Pauli
+paramagnetism on the unpaired quasiparticles in the vortex cores is directly
+evident from the ratio of scattered intensities due to the longitudinal and
+transverse vortex lattice field modulation.",1602.06463v1
+2016-02-24,Lattice Boltzmann simulations of 3D crystal growth: Numerical schemes for a phase-field model with anti-trapping current,"A lattice-Boltzmann (LB) scheme, based on the Bhatnagar-Gross-Krook (BGK)
+collision rules is developed for a phase-field model of alloy solidification in
+order to simulate the growth of dendrites. The solidification of a binary alloy
+is considered, taking into account diffusive transport of heat and solute, as
+well as the anisotropy of the solid-liquid interfacial free energy. The
+anisotropic terms in the phase-field evolution equation, the phenomenological
+anti-trapping current (introduced in the solute evolution equation to avoid
+spurious solute trapping), and the variation of the solute diffusion
+coefficient between phases, make it necessary to modify the equilibrium
+distribution functions of the LB scheme with respect to the one used in the
+standard method for the solution of advection-diffusion equations. The effects
+of grid anisotropy are removed by using the lattices D3Q15 and D3Q19 instead of
+D3Q7. The method is validated by direct comparison of the simulation results
+with a numerical code that uses the finite-difference method. Simulations are
+also carried out for two different anisotropy functions in order to demonstrate
+the capability of the method to generate various crystal shapes.",1602.07483v1
+2016-02-25,Nonequilibrium current-carrying steady states in the anisotropic $XY$ spin chain,"Out-of-equilibrium behavior is explored in the one-dimensional anisotropic
+$XY$ model. Initially preparing the system in the isotropic $XX$ model with a
+linearly varying magnetic field to create a domain-wall magnetization profile,
+dynamics is generated by rapidly changing the exchange interaction anisotropy
+and external magnetic field. Relaxation to a nonequilibrium steady state is
+studied analytically at the critical transverse Ising point, where correlation
+functions may be computed in closed form. For arbitrary values of anisotropy
+and external field, an effective generalized Gibbs' ensemble is shown to
+accurately describe observables in the long-time limit. Additionally, we find
+spatial oscillations in the exponentially decaying, transverse spin-spin
+correlation functions with wavelength set by the magnetization jump across the
+initial domain wall. This wavelength depends only weakly on anisotropy and
+magnetic field in contrast to the current, which is highly dependent on these
+parameters.",1602.08027v2
+2016-03-02,Voltage controlled core reversal of fixed magnetic skyrmions without a magnetic field,"Using micromagnetic simulations we demonstrate core reversal of a fixed
+magnetic skyrmion by modulating the perpendicular magnetic anisotropy of a
+nanomagnet with an electric field. We can switch reversibly between two
+skyrmion states and two ferromagnetic states, i.e. skyrmion states with the
+magnetization of the core pointing down/up and periphery pointing up/down, and
+ferromagnetic states with magnetization pointing up/down, by sequential
+increase and decrease of the perpendicular magnetic anisotropy. The switching
+between these states is explained by the fact that the spin texture
+corresponding to each of these stable states minimizes the sum of the magnetic
+anisotropy, demagnetization, Dzyaloshinskii-Moriya interaction (DMI) and
+exchange energies. This could lead to the possibility of energy efficient
+nanomagnetic memory and logic devices implemented with fixed skyrmions without
+using a magnetic field and without moving skyrmions with a current.",1603.00927v1
+2016-03-03,Giant isotropic Nernst effect in an anisotropic Kondo semimetal,"The ""failed Kondo insulator"" CeNiSn has long been suspected to be a nodal
+metal, with a node in the hybridization matrix elements. Here we carry out a
+series of Nernst effect experiments to delineate whether the severely
+anisotropic magnetotransport coefficients do indeed derive from a nodal metal
+or can simply be explained by a highly anisotropic Fermi surface. Our
+experiments reveal that despite an almost 20-fold anisotropy in the Hall
+conductivity, the large Nernst signal is isotropic. Taken in conjunction with
+the magnetotransport anisotropy, these results provide strong support for an
+isotropic Fermi surface with a large anisotropy in quasiparticle mass derived
+from a nodal hybridization.",1603.01258v1
+2016-03-08,Gravitational Baryogenesis after Anisotropic Inflation,"The gravitational baryogensis may not generate a sufficient baryon asymmetry
+in the standard thermal history of the Universe when we take into account the
+gravitino problem. Hence it has been suggested that anisotropy of the Universe
+can enhance the generation of the baryon asymmetry through the increase of the
+time change of the Ricci scalar curvature. We study the gravitational
+baryogenesis in the presence of anisotropy, which is produced at the end of an
+anisotropic inflation. Although we confirm that the generated baryon asymmetry
+is enhanced compared with the original isotropic cosmological model, taking
+into account the constraint on the anisotropy by the recent CMB observations,
+we find that it is still difficult to obtain the observed baryon asymmetry only
+through the gravitational baryogenesis without suffering from the gravitino
+problem.",1603.02403v2
+2016-03-10,Stability and dynamics of anisotropically-tumbling chemotactic swimmers,"Micro-swimmers such as bacteria perform random walks known as run-and-tumbles
+to move up chemo-attractant gradients and as a result aggregate with others. It
+is also known that such micro-swimmers can self-organize into macroscopic
+patterns due to interactions with neighboring cells through the fluidic
+environment they live in. While the pattern formation resulting from
+chemotactic and hydrodynamic interactions separately and together have been
+previously investigated, the effect of the anisotropy in the tumbles of
+micro-swimmers has been unexplored. Here we show through linear analysis and
+full nonlinear simulations that the slight anisotropy in the individual swimmer
+tumbles can alter the collective pattern formation in non-trivial ways. We show
+that tumbling anisotropy diminishes the magnitude of the chemotactic aggregates
+but may result in more such aggregation peaks.",1603.03249v3
+2016-04-02,Ground-State Phase Diagram of the Bond-Alternating $S=2$ Quantum Spin Chain with the $XXZ$ and On-Site Anisotropies -- Symmetry Protected Topological Phase versus Trivial Phase,"We investigate the ground-state phase diagram of the bond-alternating $S=2$
+quantum spin chain with the $XXZ$ and on-site anisotropies. For the on-site
+anisotropies, in addition to the popular $D_2 \sum_j (S_j^z)^2$ term, we
+consider the $D_4 \sum_j (S_j^z)^4$ term. Mainly we use the exact
+diagonalization and the level spectroscopy analysis. We show that the Haldane
+state, large-$D$ state and the Dimer2 state belong to the same trivial phase,
+by finding the existence of adiabatic paths directly connecting these states
+without the quantum phase transition. Similarly, we show that the
+intermediate-$D$ state and the Dimer1 state belong to the same symmetry
+protected topological phase.",1604.00452v1
+2016-04-09,Anisotropy of in-plane hole g-factor in CdTe/ZnTe quantum dots,"Optical studies of a bright exciton provide only limited information about
+the hole anisotropy in a quantum dot. In this work we present a universal
+method to study heavy hole anisotropy using a dark exciton in a moderate
+in-plane magnetic field. By analysis of the linear polarization of the dark
+exciton photoluminescence we identify both isotropic and anisotropic
+contributions to the hole g-factor. We employ this method for a number of
+individual self-assembled CdTe/ZnTe quantum dots, demonstrating a variety of
+behaviors of in-plane hole g-factor: from almost fully anisotropic to almost
+isotropic. We conclude that, in general, both contributions play an important
+role and neither contribution can be neglected.",1604.02591v1
+2016-04-11,All-Optical Study of Tunable Ultrafast Spin Dynamics in [Co/Pd]-NiFe Systems: The Role of Spin-Twist Structure on Gilbert Damping,"We investigate optically induced ultrafast magnetization dynamics in [Co(0.5
+nm)/Pd(1 nm)]x5/NiFe(t) exchange-spring samples with tilted perpendicular
+magnetic anisotropy using a time-resolved magneto-optical Kerr effect
+magnetometer. The competition between the out-of-plane anisotropy of the hard
+layer, the in-plane anisotropy of the soft layer and the applied bias field
+reorganizes the spins in the soft layer, which are modified further with the
+variation in t. The spin-wave spectrum, the ultrafast demagnetization time, and
+the extracted damping coefficient all depend on the spin distribution in the
+soft layer, while the latter two also depend on the spin-orbit coupling between
+the Co and Pd layers. The spin-wave spectra change from multimode to
+single-mode as t increases. At the maximum field reached in this study, H=2.5
+kOe, the damping shows a nonmonotonic dependence on t with a minimum at t=7.5
+nm. For t<7.5 nm, intrinsic effects dominate, whereas for t>7.5 nm, extrinsic
+effects govern the damping mechanisms.",1604.02998v1
+2016-04-11,Edge anisotropy and the geometric perspective on flow networks,"Spatial networks have recently attracted great interest in various fields of
+research. While the traditional network-theoretic viewpoint is commonly
+restricted to their topological characteristics (often disregarding existing
+spatial constraints), this work takes a geometric perspective, which considers
+vertices and edges as objects in a metric space and quantifies the
+corresponding spatial distribution and alignment. For this purpose, we
+introduce the concept of edge anisotropy and define a class of measures
+characterizing the spatial directedness of connections. Specifically, we
+demonstrate that the local anisotropy of edges incident to a given vertex
+provides useful information about the local geometry of geophysical flows based
+on networks constructed from spatio-temporal data, which is complementary to
+topological characteristics of the same flow networks. Taken both structural
+and geometric viewpoints together can thus assist the identification of
+underlying flow structures from observations of scalar variables.",1604.03100v1
+2016-05-07,Order-by-disorder effects in antiferromagnets on face-centered cubic lattice,"We discuss the role of quantum fluctuations in Heisenberg antiferromagnets on
+face-centered cubic lattice with small dipolar interaction in which the
+next-nearest-neighbor exchange coupling dominates over the nearest-neighbor
+one. It is well known that a collinear magnetic structure which contains (111)
+ferromagnetic planes arranged antiferromagnetically along one of the space
+diagonals of the cube is stabilized in this model via order-by-disorder
+mechanism. On the mean-field level, the dipolar interaction forces spins to lie
+within (111) planes. By considering 1/S - corrections to the ground state
+energy, we demonstrate that quantum fluctuations lead to an anisotropy within
+(111) planes favoring three equivalent directions for the staggered
+magnetization (e.g., $[11\overline{2}]$, $[1\overline{2}1]$, and
+$[\overline{2}11]$ directions for (111) plane). Such in-plane anisotropy was
+obtained experimentally in related materials MnO, $\alpha$-MnS, $\alpha$-MnSe,
+EuTe, and EuSe. We find that the order-by-disorder mechanism can contribute
+significantly to the value of the in-plane anisotropy in EuTe. Magnon spectrum
+is also derived in the first order in 1/S.",1605.02208v2
+2016-05-12,Near isotropic behaviour of turbulent thermal convection,"We investigate the anisotropy in turbulent convection in a 3D box using
+direct numerical simulation. We compute the anisotropic parameter $A =
+u_\perp^{2}/(2u_{\parallel}^{2})$, where $u_{\perp}$ and $u_{\parallel}$ are
+the components of velocity perpendicular and parallel to the buoyancy
+direction, the shell and ring spectra, and shell-to-shell energy transfers. We
+observe that the flow is nearly isotropic for the Prandtl number $\mathrm{Pr}
+\approx 1$, but the anisotropy increases with the Prandtl number. For
+$\mathrm{Pr}=\infty$, $A \approx 0.3$, thus anisotropy is not very significant
+even in extreme cases. We also observe that $u_{\parallel}$ feeds energy to
+$u_{\perp}$ via pressure. The computation of shell-to-shell energy transfers
+reveals that the energy transfer in turbulent convection is local and forward,
+similar to hydrodynamic turbulence. These results are consistent with the
+Kolmogorov's spectrum observed by Kumar et al.~[Phys. Rev. E {\bf 90}, 023016
+(2014)] for turbulent convection.",1605.03725v2
+2016-05-20,Deciphering the Dipole Anisotropy of Galactic Cosmic Rays,"Recent measurements of the dipole anisotropy in the arrival directions of
+Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole
+amplitude and phase in the TeV-PeV range. We argue here that these observations
+can be well understood within standard diffusion theory as a combined effect of
+(i) one or more local sources at Galactic longitude 120deg < l < 300deg
+dominating the CR gradient below 0.1-0.3 PeV, (ii) the presence of a strong
+ordered magnetic field in our local environment, (iii) the relative motion of
+the solar system, and (iv) the limited reconstruction capabilities of
+ground-based observatories. We show that an excellent candidate of the local CR
+source responsible for the dipole anisotropy at 1-100 TeV is the Vela supernova
+remnant.",1605.06446v2
+2016-05-26,Tensor Squeezed Limits and the Higuchi Bound,"We point out that tensor consistency relations-i.e. the behavior of
+primordial correlation functions in the limit a tensor mode has a small
+momentum-are more universal than scalar consistency relations. They hold in the
+presence of multiple scalar fields and as long as anisotropies are diluted
+exponentially fast. When de Sitter isometries are approximately respected
+during inflation this is guaranteed by the Higuchi bound, which forbids the
+existence of light particles with spin: De Sitter space can support scalar hair
+but no curly hair. We discuss two indirect ways to look for the violation of
+tensor con- sistency relations in observations, as a signature of models in
+which inflation is not a strong isotropic attractor, such as solid inflation:
+(a) Graviton exchange contribution to the scalar four-point function; (b)
+Quadrupolar anisotropy of the scalar power spectrum due to super-horizon tensor
+modes. This anisotropy has a well-defined statistics which can be distinguished
+from cases in which the background has a privileged direction.",1605.08424v2
+2016-06-08,Observing magnetic anisotropy in electronic transport through individual single-molecule magnets,"We review different electron transport methods to probe the magnetic
+properties, such as the magnetic anisotropy, of an individual Fe4 SMM. The
+different approaches comprise first and higher order transport through the
+molecule. Gate spectroscopy, focusing on the charge degeneracy-point, is
+presented as a robust technique to quantify the longitudinal magnetic
+anisotropy of the SMM in different redox states. We provide statistics showing
+the robustness and reproducibility of the different methods. In addition,
+conductance measurements typically show high-energy excited states well beyond
+the ground spin multiplet of SMM. Some of these excitations have their origin
+in excited spin multiplets, others in vibrational modes of the molecule. The
+interplay between vibrations, charge and spin may yield a new approach for spin
+control.",1606.02572v1
+2016-06-20,Tamm-Langmuir surface waves,"In this work we develop a theory of surface electromagnetic waves localized
+at the interface of periodic metal-dielectric structures. We have shown that
+the anisotropy of plasma frequency in metal layers lifts the degeneracy of
+plasma oscillations and opens a series of photonic band gaps. This results in
+appearance of surface waves with singular density of states - we refer to them
+as Tamm-Langmuir waves. Such naming is natural since we have found that their
+properties are very similar to the properties of both bulk Langmuir and surface
+Tamm waves. Depending on the anisotropy parameters, Tamm-Langmuir waves can be
+either forward or backward waves. Singular density of states and high
+sensitivity of the dispersion to the anisotropy of the structure makes
+Tamm-Langmuir waves very promising for potential applications in nanophotonics
+and biosensing.",1606.05928v1
+2016-07-18,Anisotropic composite fermions and fractional quantum Hall effect,"We study the role of anisotropy on the transport properties of composite
+fermions near Landau level filling factor $\nu=1/2$ in two-dimensional holes
+confined to a GaAs quantum well. By applying a parallel magnetic field, we tune
+the composite fermion Fermi sea anisotropy and monitor the relative change of
+the transport scattering time at $\nu=1/2$ along the principal directions.
+Interpreted in a simple Drude model, our results suggest that the scattering
+time is longer along the longitudinal direction of the composite fermion Fermi
+sea. Furthermore, the measured energy gap for the fractional quantum Hall state
+at $\nu=2/3$ decreases when anisotropy becomes significant. The decrease,
+however, might partly stem from the charge distribution becoming bilayer-like
+at very large parallel magnetic fields.",1607.05163v2
+2016-07-21,Effect of annealing on the interfacial Dzyaloshinskii-Moriya interaction in Ta/CoFeB/MgO trilayers,"The interfacial Dzyaloshinskii-Moriya interaction (DMI) has been shown to
+stabilize homochiral N\'eel-type domain walls in thin films with perpendicular
+magnetic anisotropy and as a result permit them to be propagated by a spin Hall
+torque. In this study, we demonstrate that in Ta/Co$_{20}$Fe$_{60}$B$_{20}$/MgO
+the DMI may be influenced by annealing. We find that the DMI peaks at
+$D=0.057\pm0.003$ mJ/m$^{2}$ at an annealing temperature of 230 $^{\circ}$C.
+DMI fields were measured using a purely field-driven creep regime domain
+expansion technique. The DMI field and the anisotropy field follow a similar
+trend as a function of annealing temperature. We infer that the behavior of the
+DMI and the anisotropy are related to interfacial crystal ordering and B
+expulsion out of the CoFeB layer as the annealing temperature is increased.",1607.06405v1
+2016-07-25,Amplification of the diamagnetic response in small Hubbard rings,"In this paper, we present a study of the electric transport properties of
+small discrete rings with $3\leq N\leq 6$ sites and $N_{e}<2N$ electrons, which
+can be seen as a simplified version of real aromatic molecules. In particular,
+the ring with six sites and six electrons is our prototype of the benzene
+molecule. It is already known that the Hubbard model itself cannot account for
+the anisotropy of the diamagnetic susceptibility of the aromatic molecules,
+which is observed when they are subjected to an external magnetic field
+perpendicular to their basal plane. Therefore, we propose an extension of the
+Hubbard model, with an ad hoc extra interaction term, with two adjustable
+parameters. Our results show that this extension of the Hubbard model is able
+to amplify the persistent currents established in the ground state of our rings
+and, moreover, promotes an enhancement of the magnetic susceptibility
+anisotropy depending on the tuning of the adjustable parameters. In particular,
+for the prototype of the benzene molecule, we recover the order of magnitude of
+the diamagnetic anisotropy measured for this molecule.",1607.07473v1
+2016-07-29,An Asymptotic Preserving method for strongly anisotropic diffusion equations based on field line integration,"In magnetized plasma, the magnetic field confines the particles around the
+field lines. The anisotropy intensity in the viscosity and heat conduction may
+reach the order of $10^{12}$. When the boundary conditions are periodic or
+Neumann, the strong diffusion leads to an ill-posed limiting problem. To remove
+the ill-conditionedness in the highly anisotropic diffusion equations, we
+introduce a simple but very efficient asymptotic preserving reformulation in
+this paper. The key idea is that, instead of discretizing the Neumann boundary
+conditions locally, we replace one of the Neumann boundary condition by the
+integration of the original problem along the field line, the singular
+$1/\epsilon$ terms can be replaced by $O(1)$ terms after the integration, so
+that yields a well-posed problem. Small modifications to the original code are
+required and no change of coordinates nor mesh adaptation are needed.
+  Uniform convergence with respect to the anisotropy strength $1/\epsilon$ can
+be observed numerically and the condition number does not scale with the
+anisotropy.",1608.00541v1
+2016-07-29,Mesostructure anisotropy of bacterial cellulose-polyacrylamide hydrogels as studied by spin-echo small-angle neutron scattering,"The submicron- and micron-scale structures of composite hydrogels based on
+bacterial cellulose (BC) and polyacrylamide were studied by spin-echo
+small-angle neutron scattering (SESANS). These hydrogels were synthesized via
+free-radical polymerization of acrylamide carried out in pellicle of BC swollen
+in the reaction solution. No neutron scattering was observed for the samples
+swollen in heavy water to the equilibrium state, but a SESANS signal appeared
+when TbCl$_{3}$ salt was added to the solvent. The SESANS dependences obtained
+for these samples revealed the anisotropy of mesostructure for the hydrogels
+under investigation. Density inhomogeneities on the characteristic scale of
+11.5 $\pm$ 0.5 $\mu$m were detected in one specific orientation of the sample,
+i.e. with growth plane of BC parallel to plane formed by neutron beam and
+spin-echo length. The uniaxial anisotropy revealed agrees with the proposed
+model, which attributes this behavior to the existence of the tunnel-like
+oriented structures inside BC.",1608.00544v1
+2016-08-03,Stiffer double-stranded DNA in two-dimensional confinement due to bending anisotropy,"Using analytical approach and Monte-Carlo (MC) simulations, we study the
+elastic behaviour of the intrinsically twisted elastic ribbons with bending
+anisotropy, such as double-stranded DNA (dsDNA), in two-dimensional (2D)
+confinement. We show that, due to the bending anisotropy, the persistence
+length of dsDNA in 2D conformations is always greater than 3D conformations.
+This result is in consistence with the measured values for DNA persistence
+length in 2D and 3D in equal biological conditions. We also show that in 2D, an
+anisotropic, intrinsically twisted polymer exhibits an implicit twist-bend
+coupling, which leads to the kink formations with a half helical turn
+periodicity along the bent polymer.",1608.01347v2
+2016-08-08,Anisotropy of the infrared-active phonon modes in the mono-domain state of tetragonal SrTiO3 (110),"With infrared and terahertz ellipsometry we investigated the anisotropy of
+the infrared active phonon modes in SrTiO3 (110) single crystals in the
+tetragonal state below the so-called antiferrodistortive transition at T* = 105
+K. In particular, we show that the anisotropy of the oscillator strength of the
+so-called R-mode, which becomes weakly infrared active below T*, is a valuable
+indicator for the orientation of the structural domains. Our results reveal
+that a mono-domain state with the tetragonal axis (c-axis) parallel to the
+[001] direction can be created by applying a moderate uniaxial stress of about
+2.3 MPa along the [1-10] direction (with a mechanical clamp). The resulting,
+intrinsic splitting of the infrared-active phonon modes is reported.",1608.02329v1
+2016-08-09,Lateral-drag Casimir forces induced by anisotropy,"We predict the existence of lateral drag forces near the flat surface of an
+absorbing slab of an anisotropic material. The forces originate from the
+fluctuations of the electromagnetic field, when the anisotropy axis of the
+material forms a certain angle with the surface. In this situation, the spatial
+spectra of the fluctuating electromagnetic fields becomes asymmetric, different
+for positive and negative transverse wave vectors components. Differently from
+the case of van der Waals interactions in which the forward-backward symmetry
+is broken due to the particle movement or in quantum noncontact friction where
+it is caused by the mutual motion of the bodies, in our case the lateral motion
+results merely from the anisotropy of the slab. This new effect, of particular
+significance in hyperbolic materials, could be used for the manipulation of
+nanoparticles.",1608.03200v1
+2016-08-29,"In-plane anisotropic magnetoresistance in antiferromagnetic Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$ and Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$","Using the Kubo-Greenwood formalism the resistivity anisotropy for electron
+doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, hole doped (Ba$_{1-x}$K$_x$)Fe$_2$As$_2$
+and isovalently doped Ba(Fe$_{1-x}$Ru$_x$)$_2$As$_2$ in their antiferromagnetic
+state has been calculated in order to clarify the origin of this important
+phenomenon. The results show good agreement with experiment for all cases
+without considering impurity states extending over several unit cells or
+temperature induced spin fluctuations. From this it is concluded that the
+resistivity anisotropy at low temperatures is primarily caused by an in-plane
+anisotropic magnetoresistance. Accounting for the band dispersion with respect
+to $k_z$ is however mandatory to explain the results, showing the importance of
+the three-dimensional character of the electronic structure for the iron
+pnictides. Furthermore, it is shown that the counterintuitive sign of the
+resistivity anisotropy is no fundamental property but just a peculiarity of the
+anisotropic band structure.",1608.08077v1
+2016-09-05,Anderson localization of ultracold atoms: Where is the mobility edge?,"Recent experiments on non-interacting ultra-cold atoms in correlated disorder
+have yielded conflicting results regarding the so-called mobility edge, i.e.
+the energy threshold separating Anderson localized from diffusive states. At
+the same time, there are theoretical indications that the experimental data
+overestimate the position of this critical energy, sometimes by a large amount.
+The non-trivial effect of anisotropy in the spatial correlations of
+experimental speckle potentials have been put forward as a possible cause for
+such discrepancy. Using extensive numerical simulations we show that the effect
+of anisotropy alone is not sufficient to explain the experimental data. In
+particular, we find that, for not-too-strong anisotropy, realistic disorder
+configurations are essentially identical to the isotropic case, modulo a simple
+rescaling of the energies.",1609.01065v1
+2016-10-12,Grain structure dependence of coercivity in thin films,"We investigated coercive fields of 200nm x 1200nm x 5nm rectangular
+nanocrystalline thin films as a function of grain size D using finite elements
+simulations. To this end, we created granular finite element models with grain
+sizes ranging from 5nm to 60nm, and performed micromagnetic hysteresis
+calculations along the y-axis (easy direction) as well as along the x-axis
+(hard direction). We then used an extended Random Anisotropy model to interpret
+the results and to illustrate the interplay of random anisotropy and shape
+induced anisotropy, which is coherent on a much larger scale, in thin films.",1610.03630v3
+2016-10-13,Spin wave surface states in one-dimensional planar magnonic crystals,"We have investigated surface spin wave states in one-dimensional planar
+bi-component magnonic crystals, localized on the surfaces resulting from the
+breaking of the periodic structure. The two systems have been considered: the
+magnonic crystal with periodic changes of the anisotropy field in exchange
+regime and the magnonic crystal composed of Fe and Ni stripes in dipolar regime
+with exchange interactions included. We chose the symmetric unit cell for both
+systems to implement the symmetry related criteria for existence of the surface
+states. We investigated also the surface states induced by the presence of
+perturbation of the surface areas of the magnonic crystals. We showed, that the
+system with modulated anisotropy is a direct analog of the electronic crystal.
+Therefore, the surface states in both systems have the same properties. For
+surface states existing in magnonic crystals in dipolar regime we demonstrated
+that spin waves preserve distinct differences to the electronic crystals, which
+are due to long-range dynamic dipolar interactions. We found that tuning of the
+strength of magnetization pinning resulting from the surface anisotropy or
+dipolar effect is vitally important for existence of the surface states in
+magnonic crystals.",1610.04083v1
+2016-10-13,Nanoscale distribution of magnetic anisotropies in bimagnetic soft core-hard shell MnFe$_2$O$_4$@CoFe$_2$O$_4$ nanoparticles,"The nanoscale distribution of magnetic anisotropies was measured in
+core@shell MnFe$_2$O$_4$@CoFe$_2$O$_4$ 7.0 nm particles using a combination of
+element selective magnetic spectroscopies with different probing depths. As
+this picture is not accessible by any other technique, emergent magnetic
+properties were revealed. The coercive field is not constant in a whole
+nanospinel. The very thin (0.5 nm) CoFe$_2$O$_4$ hard shell imposes a strong
+magnetic anisotropy to the otherwise very soft MnFe$_2$O$_4$ core: a large
+gradient in coercivity was measured inside the MnFe$_2$O$_4$ core with lower
+values close to the interface region, while the inner core presents a
+substantial coercive field (0.54 T) and a very high remnant magnetization (90%
+of the magnetization at saturation).",1610.04263v2
+2016-10-20,Local and long-range realizations of a spin-reorientation surface phase transition,"The spin reorientation transition of an ultrathin film from perpendicular to
+in-plane magnetization is driven by a competition between dipole and anisotropy
+energies. \textit{In situ} measurements of the magnetic susceptibility of Fe/2
+ML Ni/W(110) films as a function of Fe coverage, made as the films are
+deposited at constant temperature, show two clear peaks; one at the long-range
+and one at the local realization of the transition. In the long-range
+realization, the susceptibility probes the striped domain pattern that is
+formed in response to the balance of energetics on a mesoscopic scale. Here the
+reorientation transition occurs at a non-integer layer thickness. In the local
+realization, the susceptibility probes the response of small islands with
+in-plane anisotropy in the 3rd atomic Fe layer that are grown on the 2nd atomic
+Fe layer, which has perpendicular anisotropy. It is a response to the local
+finite-size, metastable energetics due to discrete steps in thickness. An
+excellent quantitative description of the susceptibility data is obtained when
+both local and long-range aspects of the spin reorientation transition are
+included.",1610.06446v1
+2016-10-26,Anisotropic permeability in deterministic lateral displacement arrays,"We uncover anisotropic permeability in microfluidic deterministic lateral
+displacement (DLD) arrays. A DLD array can achieve high-resolution bimodal
+size-based separation of microparticles, including bioparticles, such as cells.
+For an application with a given separation size, correct device operation
+requires that the flow remains at a fixed angle to the obstacle array. We
+demonstrate via experiments and lattice-Boltzmann simulations that subtle array
+design features cause anisotropic permeability. Anisotropic permeability
+indicates the microfluidic array's intrinsic tendency to induce an undesired
+lateral pressure gradient. This can cause an inclined flow and therefore local
+changes in the critical separation size. Thus, particle trajectories can become
+unpredictable and the device useless for the desired separation task.
+Anisotropy becomes severe for arrays with unequal axial and lateral gaps
+between obstacle posts and highly asymmetric post shapes. Furthermore, of the
+two equivalent array layouts employed with the DLD, the rotated-square layout
+does not display intrinsic anisotropy. We therefore recommend this layout over
+the easier-to-implement parallelogram layout. We provide additional guidelines
+for avoiding adverse effects of anisotropy on the DLD.",1610.08427v2
+2016-10-27,Holographic Isotropisation in Gauss-Bonnet Gravity,"We study holographic isotropisation of homogeneous, strongly coupled,
+non-Abelian plasmas in Gauss-Bonnet gravity with a negative cosmological
+constant. We focus on small values of the Gauss-Bonnet coupling parameter
+$\lambda_{GB}$ and linearise the equations of motion around a time-dependent
+background solution with $\lambda_{GB}=0$. We numerically solve the linearised
+equations and show that the entire time evolution of the pressure anisotropy
+can be well approximated by the linear in $\lambda_{GB}$ corrections to the
+quasinormal mode expansion, even in the cases of high anisotropy. We finally
+show that, quite generally, the time evolution of the pressure anisotropy with
+the Gauss-Bonnet term is approximately {\it shifted} with respect to the
+evolution without it, with the sign of the shift being directly related to the
+sign of the $\lambda_{GB}$ parameter. This suggests that finite coupling
+corrections generically {\it increase} the isotropisation time of strongly
+coupled plasmas.",1610.08987v2
+2016-11-01,Shear softening of Earth's inner core indicated by its high Poisson's ratio and elastic anisotropy,"Earth's inner core exhibits an unusually high Poisson's ratio and noticeable
+elastic anisotropy. The mechanisms responsible for these features are critical
+for understanding the evolution of the Earth but remain unclear. This study
+indicates that once the correct formula for the shear modulus is used, shear
+softening can simultaneously explain the high Poisson's ratio and strong
+anisotropy of the inner core. Body-centred-cubic (bcc) iron shows shear
+instability at the pressures found in the inner-core and can be dynamically
+stabilized by temperature and light elements. It is very likely that some
+combinations of light elements stabilize the bcc iron alloy under inner-core
+conditions. Such a bcc phase would exhibit significant shear softening and
+match the geophysical constraints of the inner core. Identifying which light
+elements and what concentrations of these elements stabilize the bcc phase will
+provide critical information on the light elements of the inner core.",1611.00244v1
+2016-11-09,Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO heterostructures,"Voltage control of magnetic anisotropy (VCMA) in magnetic heterostructures is
+a key technology for achieving energy-efficiency electronic devices with
+ultralow power consumption. Here, we report the first demonstration of the VCMA
+effect in novel epitaxial Ru/Co2FeAl(CFA)/MgO heterostructures with interfacial
+perpendicular magnetic anisotropy (PMA). Perpendicularly magnetized tunnel
+junctions with the structure of Ru/CFA/MgO were fabricated and exhibited an
+effective voltage control on switching fields for the CFA free layer. A large
+VCMA coefficient of 108 (139) fJ/Vm for the CFA film was achieved at room
+temperature (4 K). The interfacial stability in the heterostructure was
+confirmed by repeating measurements. Temperature dependences of both the
+interfacial PMA and the VCMA effect were also investigated. It is found that
+the temperature dependences follow power laws of the saturation magnetization
+with an exponent of ~2. The significant VCMA effect observed in this work
+indicates that the Ru/CFA/MgO heterostructure could be one of the promising
+candidates for spintronic devices with voltage control.",1611.02827v1
+2016-11-09,Anisotopic inflation with a non-abelian gauge field in Gauss-Bonnet gravity,"In presence of Gauss-Bonnet corrections, we study anisotropic inflation aided
+by a massless $SU(2)$ gauge field where both the gauge field and the
+Gauss-Bonnet term are non-minimally coupled to the inflaton. In this scenario,
+under slow-roll approximations, the anisotropic inflation is realized as an
+attractor solution with quadratic forms of inflaton potential and Gauss-Bonnet
+coupling function. We show that the degree of anisotropy is proportional to the
+additive combination of two slow-roll parameters of the theory. The anisotropy
+may become either positive or negative similar to the non-Gauss-Bonnet
+framework, a feature of the model for anisotropic inflation supported by a
+non-abelian gauge field but the effect of Gauss-Bonnet term further enhances or
+suppresses the generated anisotropy.",1611.03037v2
+2016-11-10,Energy efficient and fast reversal of a fixed skyrmions with spin current assisted by voltage controlled magnetic anisotropy,"Recent work [1,2] suggests that ferromagnetic reversal with spin transfer
+torque (STT) requires more current in a system in the presence of DMI than
+switching a typical ferromagnet of the same dimensions and perpendicular
+magnetic anisotropy (PMA). However, DMI promotes stabilization of skyrmions and
+we report that when the perpendicular anisotropy is modulated (reduced) for
+both the skyrmion and ferromagnet, it takes much smaller current to reverse the
+fixed skyrmion than to reverse the ferromagnet in the same time, or the
+skyrmion reverses much faster than the ferromagnet at similar levels of
+current. We show with rigorous micromagnetic simulations and energy portraits
+that the skyrmion switching proceeds along a different path at very low PMA
+which results in a significant reduction in the spin current required or time
+required for reversal. This can have potential for memory application where a
+relatively simple modification of the standard STT-RAM to include a heavy metal
+adjacent to the soft magnetic layer and with appropriate design of the tunnel
+barrier can lead to energy efficient and fast magnetic memory device based on
+the reversal of fixed skyrmions.",1611.03138v2
+2016-12-07,General quadrupolar statistical anisotropy: Planck limits,"Several early Universe scenarios predict a direction-dependent spectrum of
+primordial curvature perturbations. This translates into the violation of the
+statistical isotropy of cosmic microwave background radiation. Previous
+searches for statistical anisotropy mainly focussed on a quadrupolar
+direction-dependence characterised by a single multipole vector and an overall
+amplitude $g_*$. Generically, however, the quadrupole has a more complicated
+geometry described by two multipole vectors and $g_*$. This is the subject of
+the present work. In particular, we limit the amplitude $g_*$ for different
+shapes of the quadrupole by making use of Planck 2015 maps. We also constrain
+certain inflationary scenarios which predict this kind of more general
+quadrupolar statistical anisotropy.",1612.02347v2
+2016-12-07,Effect of anisotropy on generalized Chaplygin gas scalar field and its interaction with other dark energy models,"In this work, we establish a correspondence between the interacting
+holographic, new agegraphic dark energy and generalized Chaplygin gas model in
+Bianchi type I universe. In continue, we reconstruct the potential of the
+scalar field which describes the generalized Chaplygin cosmology. Cosmological
+solutions are obtained when the kinetic energy of the phantom field is order of
+the anisotropy and dominates over the potential energy of the field. We
+investigate observational constraints on the generalized Chaplygin gas,
+holographic and new agegraphic dark energy models as the unification of dark
+matter and dark energy, by using the latest observational data. To do this we
+focus on observational determinations of the expansion history $H(z)$. It is
+shown that the HDE model is better than the NADE and generalized Chaplygin gas
+models in an anisotropic universe. Then, we calculate the evolution of density
+perturbations in the linear regime for three models of dark energy and compare
+the results $\Lambda$CDM model. Finally, the analysis shows that the increase
+in anisotropy leads to more correspondence between the dark energy scalar field
+model and observational data",1612.02453v1
+2016-12-28,2D SnS: a phosphorene analogue with strong in-plane electronic anisotropy,"We study the anisotropic electronic properties of 2D SnS, an analogue of
+phosphorene, grown by physical vapor transport. With transmission electron
+microscope and polarized Raman spectroscopy, we identify the zigzag and
+armchair directions of the as-grown 2D crystals. 2D SnS field-effect
+transistors with a cross-Hall-bar structure are fabricated. They show heavily
+hole-doped (~10$^{19}$ cm$^{-3}$) conductivity with strong in-plane anisotropy.
+At room temperature the mobility along the zigzag direction exceeds 20
+cm$^{2}$V$^{-1}$s$^{-1}$, which can be up to 1.7 times of that in the armchair
+direction. This strong anisotropy is then explained by the effective-mass ratio
+along the two directions and agrees well with previous theoretical predictions.
+Temperature-dependent carrier density is used to find out the acceptor energy
+level to be ~45 meV above the valence band maximum. This value matches with a
+calculated defect level of 42 meV for Sn vacancies, indicating that Sn
+deficiency is the main cause of the p-type conductivity.",1612.08896v1
+2017-01-09,"Magnetic properties of ultra-thin 3d transition-metal binary alloys I: spin and orbital moments, anisotropy, and confirmation of Slater-Pauling behavior","The structure and static magnetic properties - saturation magnetization,
+perpendicular anisotropy, spectroscopic g-factor, and orbital magnetization -
+of thin-film 3d transition metal alloys are determined over the full range of
+alloy compositions via X-ray diffraction, magnetometry, and ferromagnetic
+resonance measurements. We determine the interfacial perpendicular magnetic
+anisotropy by use of samples sets with varying thickness for specific alloy
+concentrations. The results agree with prior published data and theoretical
+predictions. They provide a comprehensive compilation of the magnetic
+properties of thin-film Ni-Co, Ni-Fe and Co-Fe alloys that goes well beyond the
+often-cited Slater-Pauling dependence of magnetic moment on alloy
+concentration.",1701.02177v1
+2017-01-14,Strong perpendicular magnetic anisotropy energy density at Fe alloy/HfO2 interfaces,"We report on the perpendicular magnetic anisotropy (PMA) behavior of heavy
+metal (HM)/ Fe alloy/MgO thin film heterostructures after an ultrathin HfO2
+passivation layer is inserted between the Fe alloy and the MgO. This is
+accomplished by depositing one to two atomic layers of Hf onto the Fe alloy
+before the subsequent rf sputter deposition of the MgO layer. This Hf layer is
+fully oxidized during the subsequent deposition of the MgO layer, as confirmed
+by X-ray photoelectron spectroscopy measurements. As the result a strong
+interfacial perpendicular anisotropy energy density can be achieved without any
+post-fabrication annealing treatment, for example 1.7 erg/cm^2 for the
+Ta/Fe60Co20B20/HfO2/MgO heterostructure. Depending on the HM, further
+enhancements of the PMA can be realized by thermal annealing to at least 400C.
+We show that ultra-thin HfO2 layers offer a range of options for enhancing the
+magnetic properties of magnetic heterostructures for spintronics applications.",1701.03933v1
+2017-01-24,Momentum anisotropy effects for quarkonium in a weakly-coupled quark-gluon plasma below the melting temperature,"In the early stages of heavy-ion collisions, the hot QCD matter expands more
+longitudinally than transversely. This imbalance causes the system to become
+rapidly colder in the longitudinal direction and a local momentum anisotropy
+appears. In this paper, we study the heavy-quarkonium spectrum in the presence
+of a small plasma anisotropy. We work in the framework of pNRQCD at finite
+temperature. We inspect arrangements of non-relativistic and thermal scales
+complementary to those considered in the literature. In particular, we consider
+temperatures larger and Debye masses smaller than the binding energy, which is
+a temperature range relevant for presently running LHC experiments. In this
+setting we compute the leading thermal corrections to the binding energy and
+the thermal width induced by quarkonium gluo-dissociation.",1701.06956v1
+2017-02-03,Significant reduction of critical currents in MRAM designs using dual free layer with perpendicular and in-plane anisotropy,"One essential feature in MRAM cells is the spin torque efficiency, which
+describes the ratio of the critical switching current to the energy barrier.
+Within this paper it is reported that the spin torque efficiency can be
+improved by a factor of 3.2 by the use a of dual free layer device, which
+consists of one layer with perpendicular crystalline anisotropy and a second
+layer with in-plane crystalline anisotropy. Detailed simulations solving the
+spin transport equations simultaneously with the micromagnetics equation were
+performed in order to understand the origin of the switching current reduction
+by a factor of 4 for the dual layer structure compared to a single layer
+structure. The main reason could be attributed to an increased spin
+accumulation within the free layer due to the dynamical tilting of the
+magnetization within the in-plane region of the dual free layer.",1702.00996v2
+2017-01-16,Dynamics of magnetic nano particles in a viscous fluid driven by rotating magnetic fields,"The rotational dynamics of magnetic nano particles in rotating magnetic
+fields in the presence of thermal noise is studied both theoretically and by
+performing numerical calculations. Kinetic equations for the dynamics of
+particles with uniaxial magnetic anisotropy are studied and the phase lag
+between the rotating magnetic moment and the driving field is obtained. It is
+shown that for large enough anisotropy energy the magnetic moment is locked to
+the anisotropy axis so that the particle behaves like a rotating magnetic
+dipole. The corresponding rigid dipole model is analyzed both numerically by
+solving the appropriate Fokker-Planck equation and analytically by applying an
+effective field method. In the special case of a rotating magnetic field
+applied analytic results are obtained in perfect agreement with numerical
+results based on the Fokker-Planck equation. The analytic formulas derived are
+not restricted to small magnetic fields or low frequencies and are therefore
+important for applications. The illustrative numerical calculations presented
+are performed for magnetic parameters typical for iron oxide.",1702.04673v1
+2017-02-24,Giant perpendicular exchange bias with antiferromagnetic MnN,"We investigated an out-of-plane exchange bias system that is based on the
+antiferromagnet MnN. Polycrystalline, highly textured film stacks of Ta / MnN /
+CoFeB / MgO / Ta were grown on SiO$_x$ by (reactive) magnetron sputtering and
+studied by x-ray diffraction and Kerr magnetometry. Nontrivial modifications of
+the exchange bias and the perpendicular magnetic anisotropy were observed both
+as functions of film thicknesses as well as field cooling temperatures. In
+optimized film stacks, a giant perpendicular exchange bias of 3600 Oe and a
+coercive field of 350 Oe were observed at room temperature. The effective
+interfacial exchange energy is estimated to be $J_\mathrm{eff} = 0.24$ mJ/m$^2$
+and the effective uniaxial anisotropy constant of the antiferromagnet is
+$K_\mathrm{eff} = 24$ kJ/m$^3$. The maximum effective perpendicular anisotropy
+field of the CoFeB layer is $H_\mathrm{ani} = 3400$ Oe. These values are larger
+than any previously reported values. These results possibly open a route to
+magnetically stable, exchange biased perpendicularly magnetized spin valves.",1702.07538v2
+2017-02-26,Exploring the Optical States for Black Phosphorus: Anisotropy and Bandgap Tuning,"The dressed states arising from the interaction between electrons and holes,
+and off-resonant electromagnetic radiation have been investigated for recently
+fabricated gapped and anisotropic black phosphorus. Our calculations were
+carried out for the low-energy electronic subbands near the $\Gamma$ point.
+States for both linear and circular polarizations of the incoming radiation
+have been computed. However, our principal emphasis is on linearly polarized
+light with arbitrary polarization since this case has not been given much
+attention for dressing fields imposed on anisotropic structures. We have
+considered various cases for one- and few-layer phosphorus, including massless
+Dirac fermions with tunable in-plane anisotropy. Initial Hamiltonian parameters
+are renormalized in a largely different way compared to those for previously
+reported for gapped Dirac structures and, most importantly, existing anisotropy
+which could be modified in every direction.",1702.08058v1
+2017-03-07,Anisotropy Driven Transition from Moore-Read State to Quantum Hall Stripes,"We investigate the nature of the quantum Hall liquid in a half-filled second
+Landau level ($n=1$) as a function of band mass anisotropy using numerical
+exact diagonalization (ED) and density matrix renormalization group (DMRG)
+methods. We find increasing the mass anisotropy induces a quantum phase
+transition from the Moore-Read state to a charge density wave state. By
+analyzing the energy spectrum, guiding center structure factors and by adding
+weak pinning potentials, we show that this charge density wave is a
+uni-directional quantum Hall stripe, which has a periodicity of a few magnetic
+lengths and survives in the thermodynamic limit. We find smooth profiles for
+the guiding center occupation function that reveal the strong coupling nature
+of the array of chiral Luttinger liquids residing at the stripe edges.",1703.02167v2
+2017-03-13,Artificial control of the bias-voltage dependence of tunnelling anisotropic magnetoresistance using quantization in a single-crystal ferromagnet,"A major issue in the development of spintronic memory devices is the
+reduction of the power consumption for the magnetization reversal. For this
+purpose, the artificial control of the magnetic anisotropy of ferromagnetic
+materials is of great importance. Here, we demonstrate the control of the
+carrier-energy dependence of the magnetic anisotropy of the density of states
+(DOS) using the quantum size effect in a single-crystal ferromagnetic material,
+GaMnAs. We show that the mainly two-fold symmetry of the magnetic anisotropy of
+DOS, which is attributed to the impurity band, is changed to a four-fold
+symmetry by enhancing the quantum size effect in the valence band of the GaMnAs
+quantum wells. By combination with the gate-electric field control technique,
+our concept of the usage of the quantum size effect for the control of the
+magnetism will pave the way for the ultra-low-power manipulation of
+magnetization in future spintronic devices.",1703.04294v1
+2017-03-16,Primordial anisotropies from cosmic strings during inflation,"In this work we study the imprints of a primordial cosmic string on
+inflationary power spectrum. Cosmic string induces two distinct contributions
+on curvature perturbations power spectrum. The first type of correction
+respects the translation invariance while violating isotropy. This generates
+quadrupolar statistical anisotropy in CMB maps which is constrained by the
+Planck data. The second contribution breaks both homogeneity and isotropy,
+generating a dipolar power asymmetry in variance of temperature fluctuations
+with its amplitude falling on small scales. We show that the strongest
+constraint on the tension of string is obtained from the quadrupolar anisotropy
+and argue that the mass scale of underlying theory responsible for the
+formation of string can not be much higher than the GUT scale. The predictions
+of string for the diagonal and off-diagonal components of CMB angular power
+spectrum are presented.",1703.05714v1
+2017-03-19,Surface anisotropy of iron oxide nanoparticles and slabs from first principles : influence of coatings and ligands as a test of the Heisenberg model,"We performed ab initio computations of the magnetic properties of simple iron
+oxide clusters and slabs. We considered an iron oxide cluster functionalized by
+a molecule or glued to a gold cluster of the same size. We also considered a
+magnetite slab coated by cobalt oxide or a mixture of iron oxide and cobalt
+oxide. The changes in magnetic behavior were explored using constrained
+magnetic calculations. A possible value for the surface anisotropy was
+estimated from the fit of a classical Heisenberg model on ab initio results.
+The value was found to be compatible with estimations obtained by other means,
+or inferred from experimental results. The addition of a ligand, coating, or of
+a metallic nanoparticle to the systems degraded the quality of the description
+by the Heisenberg Hamiltonian. Proposing a change in the anisotropies allowing
+for the proportion of each transition atom we could get a much better
+description of the magnetism of series of hybrid cobalt and iron oxide systems.",1703.06414v1
+2017-03-21,Hybrid straintronics and voltage-controlled-magnetic-anisotropy: Precessional switching of a perpendicular anisotropy magneto-tunneling junction without a magnetic field,"We propose an all-electric implementation of a precessionally switched
+perpendicular magnetic anisotropy magneto-tunneling-junction (p-MTJ) based
+toggle memory cell where data is written with
+voltage-controlled-magnetic-anisotropy (VCMA) without requiring an in-plane
+magnetic field. The soft layer of the MTJ is a two-phase
+(magnetostrictive/piezoelectric) multiferroic which is electrically stressed to
+produce an effective in-plane magnetic field around which the magnetization
+precesses to complete a flip when the VCMA voltage pulse duration and the
+stress duration are independently adjusted to obtain a high switching
+probability. A two-terminal energy-efficient cell, that is compatible with
+crossbar architecture and high cell density, is designed.",1703.07437v2
+2017-03-22,Anisotropy of transport in bulk Rashba metals,"The recent experimental discovery of three-dimensional (3D) materials hosting
+a strong Rashba spin-orbit coupling calls for the theoretical investigation of
+their transport properties. Here we study the zero temperature dc conductivity
+of a 3D Rashba metal in the presence of static diluted impurities. We show
+that, at variance with the two-dimensional case, in 3D systems spin-orbit
+coupling affects dc charge transport in all density regimes. We find in
+particular that the effect of spin-orbit interaction strongly depends on the
+direction of the current, and we show that this yields strongly anisotropic
+transport characteristics. In the dominant spin-orbit coupling regime where
+only the lowest band is occupied, the SO-induced conductivity anisotropy is
+governed entirely by the anomalous component of the renormalized current. We
+propose that measurements of the conductivity anisotropy in bulk Rashba metals
+may give a direct experimental assessment of the spin-orbit strength.",1703.07701v2
+2017-03-23,Theory of anomalous magnetotransport from mass anisotropy,"In underdoped YBa$_2$Cu$_3$O$_{6+x}$, there is evidence of a small Fermi
+surface pocket subject to substantial mass enhancement in the doping regime $
+0.12<p<0.16$. This mass enhancement may vary substantially over the Fermi
+surface, due to ""hot spot"" or other relevant physics. We therefore examine the
+magnetotransport of an electron-like Fermi pocket with large effective mass
+anisotropy. Within the relaxation time approximation, we show that even for a
+pocket with a fixed shape, the magnitude and sign of the Hall effect may change
+as the mass anisotropy changes (except at very large, likely inaccessible
+magnetic fields). We discuss implications for recent Hall measurements in near
+optimally doped cuprates in high fields. In addition we identify a novel
+intermediate asymptotic regime of magnetic field, characterized by B-linear
+magnetoresistance. Similar phenomena should occur in a variety of other
+experimental systems with anisotropic mass enhancement",1703.08187v2
+2017-04-10,Patterned growth of crystalline Y$_{3}$Fe$_{5}$O$_{12}$ nanostructures with engineered magnetic shape anisotropy,"We demonstrate patterned growth of epitaxial yttrium iron garnet (YIG) thin
+films using lithographically defined templates on gadolinium gallium garnet
+(GGG) substrates. The fabricated YIG nanostructures yield the desired
+crystallographic orientation, excellent surface morphology, and narrow
+ferromagnetic resonance (FMR) linewidth (~ 4 Oe). Shape-induced magnetic
+anisotropy is clearly observed in a patterned array of nanobars engineered to
+exhibit the larger coercivity (40 Oe) compared with that of continuous films.
+Both hysteresis loop and angle-dependent FMR spectra measurements indicate that
+the easy axis aligns along the longitudinal direction of the nanobars, with an
+effective anisotropy field of 195 Oe. Our work overcomes difficulties in
+patterning YIG thin films and provides an effective means to control their
+magnetic properties and magnetic bias conditions.",1704.03056v2
+2017-04-04,Magnetic Dipole Interaction and Total Magnetic Energy of Lithium Ferrire Thin Films,"The total magnetic energy of Lithium ferrite thin films was determined using
+the classical Heisenberg Hamiltonian. The short range magnetic dipole
+interactions between spins within one unit cell and the interactions between
+spins in two adjacent unit cells have been determined in order to find the
+total magnetic energy of lithium ferrite films. Only the spin pairs with
+separation less than cell constant have been taken into account to calculate
+dipole interaction and spin exchange interaction. Theoretically several easy
+and hard directions of lithium ferrite film were found for one set of energy
+parameters included in our modified Heisenberg Hamiltonian. The dependence of
+total magnetic energy of a lithium ferrite film on number of unit cells, spin
+exchange interaction, dipole interaction, second order magnetic anisotropy,
+fourth order magnetic anisotropy, internal applied magnetic field and stress
+induced magnetic anisotropy has been explained in this manuscript.",1704.03314v1
+2017-04-11,Can anisotropy in the galaxy distribution tell the bias?,"We use information entropy to analyze the anisotropy in the mock galaxy
+catalogues from dark matter distribution and simulated biased galaxy
+distributions from $\Lambda$CDM N-body simulation. We show that one can recover
+the linear bias parameter of the simulated galaxy distributions by comparing
+the radial, polar and azimuthal anisotropies in the simulated galaxy
+distributions with that from the dark matter distribution. This method for
+determination of the linear bias requires only $O(N)$ operations as compared to
+$O(N^{2})$ or at least $O(N \log N)$ operations required for the methods based
+on the two-point correlation function and the power spectrum. We apply this
+method to determine the linear bias parameter for the galaxies in the 2MASS
+Redshift Survey (2MRS) and find that the 2MRS galaxies in the $K_{s}$ band have
+a linear bias of $\sim 1.3$.",1704.03405v1
+2017-04-12,Predicting reaction coordinates in energy landscapes with diffusion anisotropy,"We consider a range of model potentials with metastable states undergoing
+molecular dynamics coupled to a thermal bath in the high friction regime, and
+consider how the optimal reaction coordinate depends on the diffusion
+anisotropy. For this we use our recently proposed method 'Spectral gap
+optimization of order parameters (SGOOP)' (Tiwary and Berne, Proc. Natl. Acad.
+Sci. 113 2839 2016). We show how available information about dynamical
+observables in addition to static information can be incorporated into SGOOP,
+which can then be used to accurately determine the 'best' reaction coordinate
+for arbitrary anisotropies. We compare our results with transmission
+coefficient calculations and published benchmarks where applicable or available
+respectively.",1704.03912v2
+2017-04-13,Cardiac re-entry dynamics & self-termination in DT-MRI based model of Human Foetal Heart,"The effect of heart geometry and anisotropy on cardiac re-entry dynamics and
+self-termination is studied here in anatomically realistic computer simulations
+of human foetal heart. 20 weeks of gestational age human foetal heart isotropic
+and anisotropic anatomy models from diffusion tensor MRI data sets are used in
+the computer simulations. The fibre orientation angles of the heart were
+obtained from the DT-MRI primary eigenvalues. In a spatially homogeneous
+electrophysiological mono domain model with the DT-MRI based heart geometries,
+we initiate simplified Fitz-Hugh-Nagumo kinetics cardiac re-entry at a
+prescribed location in a 2D slice, and in the full 3D anatomy model. In a slice
+of the heart, the MRI based fibre anisotropy changes the re-entry dynamics from
+pinned to anatomical re-entry. In the full 3D MRI based model, the foetal heart
+fibre anisotropy changes the re-entry dynamics from a persistent re-entry to
+the re-entry self-termination.",1704.04208v2
+2017-04-24,Probing non-linearity of higher order anisotropic flow in Pb--Pb collisions,"The second and the third order anisotropic flow, $V_{2}$ and $V_3$, are
+determined by the corresponding initial spatial anisotropy coefficients,
+$\varepsilon_{2}$ and $\varepsilon_{3}$, in the initial density distribution.
+On the contrary, the higher order anisotropic flow $V_n$ ($n > 3$), in addition
+to their dependence on the same order initial anisotropy coefficient
+$\varepsilon_{n}$, have a significant contribution from lower order initial
+anisotropy coefficients, which leads to mode-coupling effects. In this
+contribution, we present the investigations on linear and non-linear modes in
+higher order anisotropic flow ($V_{4}$, $V_{5}$ and $V_{6}$) in Pb--Pb
+collisions at $\sqrt{s_{\rm NN}} =$ 2.76 TeV using the ALICE detector at the
+Large Hadron Collider (LHC). A significant contribution from a non-linear mode
+is observed. A new observable, the non-linear response coefficient, is measured
+as well. The comparison to theoretical calculations provides crucial
+information on dynamic of the created system especially at the freeze-out
+conditions, which are poorly known from previous flow measurements.",1704.07070v1
+2017-04-28,Strong anisotropy effect in iron-based superconductor CaFe$_{0.882}$Co$_{0.118}$AsF,"The anisotropy of the Fe-based superconductors is much smaller than that of
+the cuprates and the theoretical calculations. A credible understanding for
+this experimental fact is still lacking up to now. Here we experimentally study
+the magnetic-field-angle dependence of electronic resistivity in the
+superconducting phase of iron-based superconductor
+CaFe$_{0.882}$Co$_{0.118}$AsF, and find the strongest anisotropy effect of the
+upper critical field among the iron-based superconductors based on the
+framework of Ginzburg-Landau theory. The evidences of energy band structure and
+charge density distribution from electronic structure calculations demonstrate
+that the observed strong anisotropic effect mainly comes from the strong ionic
+bonding in between the ions of Ca$^{2+}$ and F$^-$, which weakens the
+interlayer coupling between the layers of FeAs and CaF. This finding provides a
+significant insight into the nature of experimentally observed strong
+anisotropic effect of electronic resistivity, and also paves an avenue to
+design exotic two dimensional artificial unconventional superconductors in
+future.",1704.08791v1
+2017-05-03,Single array of magnetic vortex disks uses in-plane anisotropy to create different logic gates,"Using micromagnetic simulation, we show that in-plane uniaxial magnetic
+anisotropy (IPUA) can be used to obtain FAN-OUT, AND and OR gates in an array
+of coupled disks with magnetic vortex configuration. First, we studied the
+influence of the direction of application of the IPUA on the energy transfer
+time ({\tau}) between two identical coupled nanodisks. We found that when the
+direction of the IPUA is along the x axis the magnetic interaction increases,
+allowing shorter values of {\tau}, while the IPUA along the y direction has the
+opposite effect. The magnetic interactions between the nanodisks along x and y
+directions (the coupling integrals) as a function of the uniaxial anisotropy
+constant (K {\sigma} ) were obtained using a simple dipolar model. Next, we
+demonstrated that choosing a suitable direction of application of the IPUA, it
+is possible to create several different logic gates with a single array of
+coupled nanodisks",1705.01232v1
+2017-05-09,Extreme anisotropy and anomalous transport properties of heavily electron doped Lix(NH3)yFe2Se2 single crystals,"The missing hole packets near the Brillouin zone center render unique
+electronic structures to the heavily electron doped FeSe-based superconductors
+with Tc above 40 K. It challenges the existing scenario accounting for the
+nature of superconductivity in the iron-based family. Yet, one hurdle that has
+to be overcome is the materials complexity in the rather limited number of
+compounds. Here we report the growth of heavily electron doped Li-NH3
+intercalated FeSe single crystals that are free of such complexities and allow
+access to the intrinsic superconducting properties. Our results show extremely
+large electronic anisotropy in both normal and superconducting states.
+Moreover, the anomalous transport properties appear in normal state, which are
+believed related to the anisotropy of relaxation time and/or temperature
+dependent electron carrier concentration. In view of the great chemical
+flexibility of intercalants, our findings provide novel platform to
+understanding of superconductivity origin of FeSe-related superconductors.",1705.03301v1
+2017-05-11,Linear and non-linear flow mode in Pb-Pb collisions at $\sqrt{s_{\rm NN}} =$ 2.76 TeV,"The second and the third order anisotropic flow, $V_{2}$ and $V_3$, are
+mostly determined by the corresponding initial spatial anisotropy coefficients,
+$\varepsilon_{2}$ and $\varepsilon_{3}$, in the initial density distribution.
+In addition to their dependence on the same order initial anisotropy
+coefficient, higher order anisotropic flow, $V_n$ ($n > 3$), can also have a
+significant contribution from lower order initial anisotropy coefficients,
+which leads to mode-coupling effects. In this Letter we investigate the linear
+and non-linear modes in higher order anisotropic flow $V_n$ for $n=4$, $5$, $6$
+with the ALICE detector at the Large Hadron Collider. The measurements are done
+for particles in the pseudorapidity range $|\eta| < 0.8$ and the transverse
+momentum range $0.2 < p_{\rm T} < 5.0$ GeV/$c$ as a function of collision
+centrality. The results are compared with theoretical calculations and provide
+important constraints on the initial conditions, including initial spatial
+geometry and its fluctuations, as well as the ratio of the shear viscosity to
+entropy density of the produced system.",1705.04377v2
+2017-05-13,"Tuning the perpendicular magnetic anisotropy, spin Hall switching current density and domain wall velocity by submonolayer insertion in Ta / CoFeB / MgO heterostructures","By submonolayer insertion of Au, Pt, or Pd into Ta / CoFeB / MgO / Ta
+heterostructures we tune the perpendicular magnetic anisotropy and the coercive
+field of the ferromagnetic layer. We demonstrate that this has a major
+influence on the spin Hall switching current density and its dependence on the
+external magnetic field. Despite a rather small effective spin Hall angle of
+$\theta_\mathrm{SH} \approx -0.07$, we obtain switching current densities as
+low as $2 \times 10^{10}$ A/m$^2$ with a 2 \AA{} Au interlayer. We find that
+the Dzyaloshinskii-Moriya interaction parameter $D$ is reduced with Au or Pd
+interlayers, and the perpendicular anisotropy field is reduced by an order of
+magnitude with the Pd interlayer. The dependence of the switching current
+density on the current pulse width is quantitatively explained with a domain
+wall nucleation and propagation model. Interface engineering is thus found to
+be a suitable route to tailor the current-induced magnetization switching
+properties of magnetic heterostructures.",1705.04800v1
+2017-05-16,Strong exchange anisotropy in YbMgGaO$_4$ from polarized neutron diffraction,"We measured the magnetic correlations in the triangular lattice spin-liquid
+candidate material YbMgGaO$_4$ via polarized neutron diffraction. The extracted
+in-plane and out-of-plane components of the magnetic structure factor show
+clear anisotropy. We found that short-range correlations persist at the lowest
+measured temperature of 52 mK and neutron scattering intensity is centered at
+the $M$ middle-point of the hexagonal Brillouin-zone edge. Moreover, we found
+pronounced spin anisotropy, with different correlation lengths for the in-plane
+and out-of-plane spin components. When comparing to a self-consistent Gaussian
+appoximation, our data clearly support a model with only first-neighbor
+coupling and strongly anisotropic exchanges.",1705.05699v1
+2017-05-23,The Sine-Gordon regime of the Landau-Lifshitz equation with a strong easy-plane anisotropy,"It is well-known that the dynamics of biaxial ferromagnets with a strong
+easy-plane anisotropy is essentially governed by the Sine-Gordon equation. In
+this paper, we provide a rigorous justification to this observation. More
+precisely, we show the convergence of the solutions to the Landau-Lifshitz
+equation for biaxial ferromagnets towards the solutions to the Sine-Gordon
+equation in the regime of a strong easy-plane anisotropy. Moreover, we
+establish the sharpness of our convergence result.
+  This result holds for solutions to the Landau-Lifshitz equation in high order
+Sobolev spaces. We first provide an alternative proof for local well-posedness
+in this setting by introducing high order energy quantities with better
+symmetrization properties. We then derive the convergence from the consistency
+of the Landau-Lifshitz equation with the Sine-Gordon equation by using
+well-tailored energy estimates. As a by-product, we also obtain a further
+derivation of the free wave regime of the Landau-Lifshitz equation.",1705.08146v1
+2017-06-05,Dynamic anisotropy in MHD turbulence induced by mean magnetic field,"In this paper, we study the development of anisotropy in strong MHD
+turbulence in the presence of a large scale magnetic field B 0 by analyzing the
+results of direct numerical simulations. Our results show that the developed
+anisotropy among the different components of the velocity and magnetic field is
+a direct outcome of the inverse cascade of energy of the perpendicular velocity
+components u? and a forward cascade of the energy of the parallel component u k
+. The inverse cascade develops for a strong B0, where the flow exhibits a
+strong vortical structure by the suppression of fluctuations along the magnetic
+field. Both the inverse and the forward cascade are examined in detail by
+investigating the anisotropic energy spectra, the energy fluxes, and the shell
+to shell energy transfers among different scales.",1706.01250v2
+2017-06-06,Temperature scaling of the Dzyaloshinsky-Moriya interaction in the spin wave spectrum,"The temperature scaling of the micromagnetic Dzyaloshinsky-Moriya exchange
+interaction is calculated for the whole range of temperature. We use Green's
+function theory to derive the finite-temperature spin wave spectrum of
+ferromagnetic systems described by a classical atomistic spin model
+Hamiltonian. Within this model, we find universal expressions for the
+temperature scaling not only of the Dzyaloshinsky-Moriya interaction but also
+of the Heisenberg exchange stiffness and the single-ion anisotropy. In the
+spirit of multiscale models, we establish a clear connection between the
+atomistic interactions and the temperature-dependent coefficients in the spin
+wave spectrum and in the micromagnetic free energy functional. We demonstrate
+that the corrections to mean-field theory or the random phase approximation for
+the temperature scaling of Dzyaloshinsky-Moriya and Heisenberg exchange
+interactions assume very similar forms. In the presence of thermal fluctuations
+and Dzyaloshinsky-Moriya interaction an anisotropy-like term emerges in the
+spin wave spectrum which, at low temperature, increases with temperature, in
+contrast to the decreasing single-ion anisotropy. We evaluate the accuracy of
+the theoretical method by comparing it to the spin wave spectrum calculated
+from Monte Carlo simulations.",1706.01684v1
+2017-06-21,Unusual anisotropy of inplane field magnetoresistance in ultra-high mobility SiGe/Si/SiGe quantum wells,"We find an unusual anisotropy of the inplane field magnetoresistance in
+ultra-high mobility SiGe/Si/SiGe quantum wells. The anisotropy depends on the
+orientation between the inplane field, $B_\parallel$, and current, $I$,
+relative to the crystallographic axes of the sample and is a consequence of the
+intrinsic ridges on the quantum well surface. For the simplest orientations
+between current and crystallographic axes, a method of recalculating the
+magnetoresistance measured at $I\perp B_\parallel$ into the one measured at
+$I\parallel B_\parallel$ is suggested and is shown to yield results that agree
+with the experiment.",1706.06919v2
+2017-06-28,Composite fermions in bands with N-fold rotational symmetry,"We study the effect of band anisotropy with discrete rotational symmetry
+$C_N$ (where $N\ge 2$) in the quantum Hall regime of two-dimensional electron
+systems. We focus on the composite Fermi liquid (CFL) at half filling of the
+lowest Landau level. We find that the magnitude of anisotropy transferred to
+the composite fermions decreases very rapidly with $N$. We demonstrate this by
+performing density matrix normalization group calculations on the CFL, and
+comparing the anisotropy of the composite fermion Fermi contour with that of
+the (non-interacting) electron Fermi contour at zero magnetic field. We also
+show that the effective interaction between the electrons after projecting into
+a single Landau level is much less anisotropic than the band, a fact which does
+not depend on filling and thus has implications for other quantum Hall states
+as well. Our results confirm experimental observations on anisotropic bands
+with warped Fermi contours, where the only detectable effect on the composite
+Fermi contour is an elliptical distortion ($N = 2$).",1706.09470v1
+2017-07-18,Pion transverse-momentum spectrum and elliptic anisotropy of partially coherent source,"In this letter, we study the pion momentum distribution of a coherent source
+and investigate the influences of coherent emission on the pion
+transverse-momentum ($p_T$) spectrum and elliptic anisotropy. With a partially
+coherent source, constructed by a conventional viscous hydrodynamics model
+(chaotic part) and a parameterized expanding coherent source model, we
+reproduce the pion $p_T$ spectrum and elliptic anisotropy coefficient
+$v_2(p_T)$ in the peripheral Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. It
+is found that the influences of coherent emission on the pion $p_T$ spectrum
+and $v_2(p_T)$ are related to the initial size and shape of the coherent
+source, largely due to the interference effect. However, the effect of source
+dynamical evolution on coherent emission is relatively small. The results of
+the partially coherent source with 33% coherent emission and 67% chaotic
+emission are consistent with the experimental measurements of the pion $p_T$
+spectrum, $v_2(p_T)$, and especially four-pion Bose-Einstein correlations.",1707.05461v4
+2017-07-25,The dipole anisotropy of WISE x SuperCOSMOS number counts,"We probe the isotropy of the Universe with the largest all-sky photometric
+redshift dataset currently available, namely WISE~$\times$~SuperCOSMOS. We
+search for dipole anisotropy of galaxy number counts in multiple redshift
+shells within the $0.10 < z < 0.35$ range, for two subsamples drawn from the
+same parent catalogue. Our results show that the dipole directions are in good
+agreement with most of the previous analyses in the literature, and in most
+redshift bins the dipole amplitudes are well consistent with $\Lambda$CDM-based
+mocks in the cleanest sample of this catalogue. In the $z<0.15$ range, however,
+we obtain a persistently large anisotropy in both subsamples of our dataset.
+Overall, we report no significant evidence against the isotropy assumption in
+this catalogue except for the lowest redshift ranges. The origin of the latter
+discrepancy is unclear, and improved data may be needed to explain it.",1707.08091v4
+2017-08-02,Implications of the Measured Angular Anisotropy at the Hidden Order Transition of URu2Si2,"The heavy fermion compound URu2Si2 continues to attract great interest due to
+the long- unidentified nature of the hidden order that develops below 17.5K.
+Here we discuss the implications of an angular survey of the linear and
+nonlinear susceptibility of URu2Si2 in the vicinity of the hidden order
+transition. While the anisotropic nature of spin fluctuations and
+low-temperature quasiparticles was previously established, our recent results
+suggest that the order parameter itself has intrinsic Ising anisotropy, and
+that moreover this anisotropy extends far above the hidden order transition.
+Consistency checks and subsequent questions for future experimental and
+theoretical studies of hidden order are discussed.",1708.00589v1
+2017-08-17,Enhanced superconductivity and anisotropy of FeTe0.6Se0.4 single crystals with Li-NH3 intercalation,"We report a systematic study of anisotropy resistivity, magnetoresistance and
+Hall effect of Li0.32(NH3)yFe2Te1.2Se0.8 single crystals. When compared to the
+parent compound FeTe0.6Se0.4, the Li-NH3 intercalation not only increases the
+superconducting transition temperature, but also enhances the electronic
+anisotropy in both normal and superconducting states. Moreover, in contrast to
+the parent compound, the Hall coefficient RH becomes negative at low
+temperature, indicating electron-type carriers are dominant due to Li doping.
+On the other hand, the sign reverse of RH at high temperature and the failure
+of scaling behavior of magnetoresistance imply that hole pockets may be still
+crossing or just below the Fermi energy level, leading to the multiband
+behavior in Li0.32(NH3)yFe2Te1.2Se0.8.",1708.05310v2
+2017-08-19,Current induced multi-mode propagating spin waves in a spin transfer torque nano-contact with strong perpendicular magnetic anisotropy,"Current induced spin wave excitations in spin transfer torque nano-contacts
+are known as a promising way to generate exchange-dominated spin waves at the
+nano-scale. It has been shown that when these systems are magnetized in the
+film plane, broken spatial symmetry of the field around the nano-contact
+induced by the Oersted field opens the possibility for spin wave mode
+co-existence including a non-linear self-localized spin-wave bullet and a
+propagating mode. By means of micromagnetic simulations, here we show that in
+systems with strong perpendicular magnetic anisotropy (PMA) in the free layer,
+two propagating spin wave modes with different frequency and spatial
+distribution can be excited simultaneously. Our results indicate that in-plane
+magnetized spin transfer nano-contacts in PMA materials do not host a solitonic
+self-localized spin-wave bullet, which is different from previous studies for
+systems with in plane magnetic anisotropy. This feature renders them
+interesting for nano-scale magnonic waveguides and crystals since magnon
+transport can be configured by tuning the applied current.",1708.05886v1
+2017-08-22,Ice-Templated W-Cu Composites with High Anisotropy,"Controlling anisotropy in self-assembled structures enables engineering of
+materials with highly directional response. Here, we harness the anisotropic
+growth of ice walls in a thermal gradient to assemble an anisotropic refractory
+metal structure, which is then infiltrated with Cu to make a composite. Using
+experiments and simulations, we demonstrate on the specific example of
+tungsten-copper composites the effect of anisotropy on the electrical and
+mechanical properties. The results are compared to isotropic tungsten-copper
+composites fabricated by standard powder metallurgical methods. Our results
+have the potential to fuel the development of more efficient materials, used in
+electrical power grids and solar-thermal energy conversion systems. The method
+presented here can be used with a variety of refractory metals and ceramics,
+which fosters the opportunity to design and functionalize a vast class of new
+anisotropic load-bearing hybrid metal composites with highly directional
+properties.",1708.06801v1
+2017-08-30,Current induced magnetization switching in PtCoCr structures with enhanced perpendicular magnetic anisotropy and spin-orbit torques,"Magnetic trilayers having large perpendicular magnetic anisotropy (PMA) and
+high spin-orbit torques (SOTs) efficiency are the key to fabricate nonvolatile
+magnetic memory and logic devices. In this work, PMA and SOTs are
+systematically studied in Pt/Co/Cr stacks as a function of Cr thickness. An
+enhanced perpendicular anisotropy field around 10189 Oe is obtained and is
+related to the interface between Co and Cr layers. In addition, an effective
+spin Hall angle up to 0.19 is observed due to the improved antidamping-like
+torque by employing dissimilar metals Pt and Cr with opposite signs of spin
+Hall angles on opposite sides of Co layer. Finally, we observed a nearly linear
+dependence between spin Hall angle and longitudinal resistivity from their
+temperature dependent properties, suggesting that the spin Hall effect may
+arise from extrinsic skew scattering mechanism. Our results indicate that 3d
+transition metal Cr with a large negative spin Hall angle could be used to
+engineer the interfaces of trilayers to enhance PMA and SOTs.",1708.09174v1
+2017-09-07,"Elastic, electronic, thermodynamic and transport properties of XOsSi (X=Nb, Ta) superconductors: A first-principles exploration","A first-principles calculation has been performed to study elastic,
+electronic, thermodynamic, transport and superconducting properties of recently
+reported osmium based two superconductors, XOsSi (X=Nb, Ta). We have calculated
+elastic constants and elastic moduli of XOsSi for the first time. The
+calculated values of bulk, Youngs, shear moduli are reasonably larger than the
+average value obtained from the rule of mixtures of the constituents. NbOsSi
+and TaOsSi both compounds are found to be relatively hard material, elastically
+stable and ductile in nature. The obtained directional bulk modulus and shear
+anisotropic factors indicate that both compounds have high elastic anisotropy.
+The shear anisotropic factors show higher elastic anisotropy than the
+percentage anisotropy in these compounds. The Debye temperature and bulk
+modulus increases with pressure but decreases with temperature as usual for
+metals. The magnetic susceptibility of TaOsSi follow the Curie law but NaOsSi
+do not follow due to its delocalized magnetic moment and electronic specific
+heat slightly deviates from the linear relationship with temperature. The
+calculated band structures of XOsSi compounds show metallic nature. In both
+cases d-orbitals have the dominating contribution to the total density of
+states. The smaller electron-phonon coupling constant implies that XOsSi (X=Nb,
+Ta) are weakly coupled superconductors.",1709.02173v1
+2017-09-07,Interaction anisotropy and the KPZ to KPZQ transition in particle deposition at the edges of drying drops,"The deposition process at the edge of evaporating colloidal drops varies with
+the shape of suspended particles. Experiments with prolate ellipsoidal
+particles suggest that the spatiotemporal properties of the deposit depend
+strongly on particle aspect ratio. As the aspect ratio increases, the particles
+form less densely-packed deposits and the statistical behavior of the deposit
+interface crosses over from the Kardar-Parisi-Zhang (KPZ) universality class to
+another universality class which was suggested to be consistent with the KPZ
+plus quenched disorder. Here, we numerically study the effect of particle
+interaction anisotropy on deposit growth. In essence, we model the ellipsoids,
+at the interface, as disk-like particles with two types of interaction patches
+that correspond to specific features at the poles and equator of the ellipsoid.
+The numerical results corroborate experimental observations and further suggest
+that the deposition transition can stem from interparticle interaction
+anisotropy. Possible extensions of our model to other systems are also
+discussed.",1709.02350v1
+2017-09-12,Evidence for short-range magnetic order in the nematic phase of FeSe from anisotropic in-plane magnetostriction and susceptibility measurements,"The nature of the nematic state in FeSe remains one of the major unsolved
+mysteries in Fe- based superconductors. Both spin and orbital physics have been
+invoked to explain the origin of this phase. Here we present experimental
+evidence for frustrated, short-range magnetic order, as suggested by several
+recent theoretical works, in the nematic state of FeSe. We use a combination of
+magnetostriction, susceptibility and resistivity measurements to probe the
+in-plane anisotropies of the nematic state and its associated fluctuations.
+Despite the absence of long-range magnetic order in FeSe, we observe a sizable
+in-plane magnetic susceptibility anisotropy, which is responsible for the
+field-induced in-plane distortion inferred from magnetostriction measurements.
+Further we demonstrate that all three anisotropies in FeSe are very similar to
+those of BaFe2As2, which strongly suggests that the nematic phase in FeSe is
+also of magnetic origin.",1709.03861v1
+2017-09-18,Growth-Induced In-Plane Uniaxial Anisotropy in V$_{2}$O$_{3}$/Ni Films,"We report on a strain-induced and temperature dependent uniaxial anisotropy
+in V$_{2}$O$_{3}$/Ni hybrid thin films, manifested through the interfacial
+strain and sample microstructure, and its consequences on the angular dependent
+magnetization reversal. X-ray diffraction and reciprocal space maps identify
+the in-plane crystalline axes of the V$_{2}$O$_{3}$; atomic force and scanning
+electron microscopy reveal oriented rips in the film microstructure.
+Quasi-static magnetometry and dynamic ferromagnetic resonance measurements
+identify a uniaxial magnetic easy axis along the rips. Comparison with films
+grown on sapphire without rips shows a combined contribution from strain and
+microstructure in the V$_{2}$O$_{3}$/Ni films. Magnetization reversal
+characteristics captured by angular-dependent first order reversal curve
+measurements indicate a strong domain wall pinning along the direction
+orthogonal to the rips, inducing an angular-dependent change in the reversal
+mechanism. The resultant anisotropy is tunable with temperature and is most
+pronounced at room temperature, which is beneficial for potential device
+applications.",1709.06100v1
+2017-10-16,On the anisotropy in the arrival directions of ultra-high-energy cosmic rays,"We present results of elaborate four-dimensional simulations of the
+propagation of ultra-high-energy cosmic rays (UHECR), which are based on a
+realistic astrophysical scenario. The distribution of the arrival directions of
+the UHECR is found to have a pronounced dipolar anisotropy and rather weak
+higher-order contributions to the angular power spectrum. This finding agrees
+well with the recent observation of a dipolar anisotropy for UHECR with arrival
+energies above 8 EeV by the Pierre Auger Observatory and constitutes an
+important prediction for other energy ranges and higher-order angular
+contributions for which sufficient experimental data are not yet available.
+Since our astrophysical scenario enables simulations that are completely
+consistent with the available data, this scenario will be a very useful basis
+for related future studies.",1710.05617v1
+2017-10-21,Spin interferometry in anisotropic spin-orbit fields,"Electron spins in a two-dimensional electron gas (2DEG) can be manipulated by
+spin-orbit (SO) fields originating from either Rashba or Dresselhaus
+interactions with independent isotropic characteristics. Together, though, they
+produce anisotropic SO fields with consequences on quantum transport through
+spin interference. Here we study the transport properties of modelled
+mesoscopic rings subject to Rashba and Dresselhaus [001] SO couplings in the
+presence of an additional in-plane Zeeman field acting as a probe. By means of
+1D and 2D quantum transport simulations we show that this setting presents
+anisotropies in the quantum resistance as a function of the Zeeman field
+direction. Moreover, the anisotropic resistance can be tuned by the Rashba
+strength up to the point to invert its response to the Zeeman field. We also
+find that a topological transition in the field texture that is associated with
+a geometric phase switching is imprinted in the anisotropy pattern. We conclude
+that resistance anisotropy measurements can reveal signatures of SO textures
+and geometric phases in spin carriers.",1710.07810v2
+2017-10-25,Spin-1 two-impurity Kondo problem on a lattice,"We present an extensive study of the two-impurity Kondo problem for spin-1
+adatoms on square lattice using an exact canonical transformation to map the
+problem onto an effective one-dimensional system that can be numerically solved
+using the density matrix renormalization group method. We provide a simple
+intuitive picture and identify the different regimes, depending on the distance
+between the two impurities, Kondo coupling $J_K$, longitudinal anisotropy $D$,
+and transverse anisotropy $E$. In the isotropic case, two impurities on
+opposite(same) sublattices have a singlet(triplet) ground state. However, the
+energy difference between the triplet ground state and the singlet excited
+state is very small and we expect an effectively four-fold degenerate ground
+state, i.e., two decoupled impurities. For large enough $J_K$ the impurities
+are practically uncorrelated forming two independent underscreened states with
+the conduction electrons, a clear non-perturbative effect. When the impurities
+are entangled in an RKKY-like state, Kondo correlations persists and the two
+effects coexist: the impurities are underscreened, and the dangling spin-$1/2$
+degrees of freedom are responsible for the inter-impurity entanglement. We
+analyze the effects of magnetic anisotropy in the development of
+quasi-classical correlations.",1710.09473v1
+2017-11-02,Resistivity scaling model for metals with conduction band anisotropy,"It is generally understood that the resistivity of metal thin films scales
+with film thickness mainly due to grain boundary and boundary surface
+scattering. Recently, several experiments and ab initio simulations have
+demonstrated the impact of crystal orientation on resistivity scaling. The
+crystal orientation cannot be captured by the commonly used resistivity scaling
+models and a qualitative understanding of its impact is currently lacking. In
+this work, we derive a resistivity scaling model that captures grain boundary
+and boundary surface scattering as well as the anisotropy of the band
+structure. The model is applied to Cu and Ru thin films, whose conduction bands
+are (quasi-)isotropic and anisotropic respectively. After calibrating the
+anisotropy with ab initio simulations, the resistivity scaling models are
+compared to experimental resistivity data and a renormalization of the fitted
+grain boundary reflection coefficient can be identified for textured Ru.",1711.00796v3
+2017-11-03,THz-driven demagnetization with Perpendicular Magnetic Anisotropy: Towards ultrafast ballistic switching,"We study THz-driven spin dynamics in thin CoPt films with perpendicular
+magnetic anisotropy. Femtosecond magneto-optical Kerr effect measurements show
+that demagnetization amplitude of about $1\%$ can be achieved with a peak THz
+electric field of $300$~kV/cm, and a corresponding peak magnetic field of
+$0.1$~T. The effect is more than an order of magnitude larger than observed in
+samples with easy-plane anisotropy irradiated with the same field strength. We
+also utilize finite-element simulations to design a meta-material structure
+that can enhance the THz magnetic field by more than an order of magnitude,
+over an area of several tens of square micrometers. Magnetic fields exceeding
+$1$~Tesla, generated in such meta-materials with the available laser-based THz
+sources, are expected to produce full magnetization reversal via ultrafast
+ballistic precession driven by the THz radiation. Our results demonstrate the
+possibility of table-top ultrafast magnetization reversal induced by THz
+radiation.",1711.01234v2
+2017-11-07,Tuning electrical and optical anisotropy of a monolayer black phosphorus magnetic superlattice,"We investigate theoretically the effects of modulated periodic perpendicular
+magnetic fields on the electronic states and optical absorption spectrum in a
+monolayer black phosphorus (phosphorene). We demonstrate that different
+phosphorene magnetic superlattice (PMS) orientations can give rise to distinct
+energy spectra, i.e., tuning the intrinsic electronic anisotropy. The Rashba
+spin-orbit coupling (RSOC) will develop a spin-splitting energy dispersion in
+this phosphorene magnetic supperlattice. Anisotropic momentum-dependent carrier
+distributions along/perpendicular to the magnetic strips are demonstrated, and
+the manipulations of these exotic properties by tuning superlattice geometry,
+magnetic field and the RSOC term (via an external electric field) are addressed
+systematically. Accordingly, we find bright-to-dark transitions in the ground
+state electron-hole pairs transition rate spectrum and PMS orientation
+dependent anisotropic optical absorption spectrum. This feature offers us a
+practical way to modulate the electronic anisotropy in phosphorene by magnetic
+superlattice configurations and detect these modulation capability by using the
+optical technique.",1711.02426v1
+2017-11-07,Spin-Orbit Coupling and Magnetic Anisotropy in Iron-Based Superconductors,"We determine theoretically the effect of spin-orbit coupling on the magnetic
+excitation spectrum of itinerant multi-orbital systems, with specific
+application to iron-based superconductors. Our microscopic model includes a
+realistic ten-band kinetic Hamiltonian, atomic spin-orbit coupling, and
+multi-orbital Hubbard interactions. Our results highlight the remarkable
+variability of the resulting magnetic anisotropy despite constant spin-orbit
+coupling. At the same time, the magnetic anisotropy exhibits robust universal
+behavior upon changes in the bandstructure corresponding to different materials
+of iron-based superconductors. A natural explanation of the observed
+universality emerges when considering optimal nesting as a resonance
+phenomenon. Our theory is also of relevance to other itinerant system with
+spin-orbit coupling and nesting tendencies in the bandstructure.",1711.02460v1
+2017-11-15,Anisotropy of the Seebeck and Nernst coefficients in parent compounds of the iron-based superconductors,"In-plane longitudinal and transverse thermoelectric phenomena in two parent
+compounds of iron-based superconductors are studied. Namely, the Seebeck (S)
+and Nernst (n) coefficients were measured in the temperature range 10 - 300 K
+for BaFe2As2 and CaFe2As2 single crystals that were detwinned in-situ. The
+thermoelectric response shows sizeable anisotropy in the spin density wave
+state (SDW) for both compounds, while some dissimilarities in the vicinity of
+the SDW transition can be attributed to the different nature of the phase
+change in BaFe2As2 and CaFe2As2. Temperature dependences of S and n can be
+described within a two-band model that contains a contribution from highly
+mobile, probably Dirac, electrons. The Dirac band seems to be rather isotropic,
+whereas most of the anisotropy in the transport phenomena could be attributed
+to ""regular"" hole-like charge carriers. We also observe that the off-diagonal
+element of the Peltier tensor axy is not the same for the a and b orthorhombic
+axes, which indicates that the widely used Mott formula is not applicable to
+the SDW state of iron-based superconductors.",1711.05831v2
+2017-11-17,Measuring anisotropic spin relaxation in graphene,"We compare different methods to measure the anisotropy of the spin-lifetime
+in graphene. In addition to out-of-plane rotation of the ferromagnetic
+electrodes and oblique spin precession, we present a Hanle experiment where the
+electron spins precess around either a magnetic field perpendicular to the
+graphene plane or around an in-plane field. In the latter case, electrons are
+subject to both in-plane and out-of-plane spin relaxation. To fit the data, we
+use a numerical simulation that can calculate precession with anisotropies in
+the spin-lifetimes under magnetic fields in any direction. Our data show a
+small, but distinct anisotropy that can be explained by the combined action of
+isotropic mechanisms, such as relaxation by the contacts and resonant
+scattering by magnetic impurities, and an anisotropic Rashba spin-orbit based
+mechanism. We also assess potential sources of error in all three types of
+experiment and conclude that the in-plane/out-of-plane Hanle method is most
+reliable.",1711.06472v2
+2017-11-28,Dendritic Growth of a Polymer on a 2D Mesoscale Square Lattice,"Dendritic growth patterns exhibiting four-fold anisotropy are observed when
+polyethylene oxide undergoes phase segregation from a solution phase to a solid
+phase. When this phase transition occurs on a substrate that has patterns of
+cross-linked polyethylene oxide resist pillars made using electron beam
+lithography, the polymer grows in between the patterns giving rise to dendritic
+growth structures exhibiting eight-fold anisotropy. This paper presents these
+experimental observations and explains the dendritic growth using principles of
+minimization of free energy associated with phase change. Numerical simulations
+are carried out using phase-field modeling, and the results are shown to
+qualitatively match experimental observations. The simulations reveal that the
+polymer assumes the anisotropy of the patterned lattice.",1711.10141v3
+2017-12-04,Renormalization of single-ion magnetic anisotropy in the absence of Kondo effect,"Inelastic spin flip excitations associated with single-ion magnetic
+anisotropy of quantum spins, can be strongly renormalized by Kondo exchange
+coupling to the conduction electrons in the substrate, as shown recently for
+the case of Co adatoms on CuN$_2$ islands. In this case differential
+conductance spectra show zero-bias anomalies due to a Kondo effect of the
+doubly degenerate ground state, and finite-bias step features due to spin flip
+excitations. Here I consider spin-1 quantum magnets with positive uniaxial
+anisotropy, where the ground state is non-degenerate and hence the Kondo effect
+does not take place. Nevertheless the renormalization of inelastic spin
+excitations due to exchange coupling by hybridization of the quantum spin with
+the conduction electrons still takes place despite the complete absence of the
+Kondo effect in the ground state. Additionally, I show that away from
+particle-hole symmetry, charge fluctuations have a similar effect to Kondo
+exchange coupling, leading to the renormalization of spin flip excitations.
+However, in contrast to the renormalization by Kondo exchange, charge
+fluctuations lead to asymmetric spectra, which for strong charge fluctuations
+can mimic Fano behavior.",1712.01005v2
+2017-12-05,A review on anisotropy analysis of spatial point patterns,"A spatial point pattern is called anisotropic if its spatial structure
+depends on direction. Several methods for anisotropy analysis have been
+introduced in the literature. In this paper, we give an overview of
+nonparametric methods for anisotropy analysis of (stationary) point patterns in
+$\mathbf{R}^2$ and $\mathbf{R}^3$. We discuss methods based on nearest
+neighbour and second order summary statistics as well as spectral and wavelet
+analysis. All techniques are illustrated on both a clustered and a regular
+example. Finally, we discuss methods for testing for isotropy as well as for
+estimating preferred directions in a point pattern.",1712.01634v2
+2017-12-05,Magneto-elastic coupling in Fe-based superconductors,"We used polarization-resolved Raman scattering to study the magneto-elastic
+coupling in the parent compounds of several families of Fe-based
+superconductors (BaFe2As2, EuFe2As2, NaFeAs, LiFeAs, FeSe and LaFeAsO). We
+observe an emergent Ag-symmetry As phonon mode in the XY scattering geometry
+whose intensity is significantly enhanced below the magneto-structural
+transition only for compounds showing magnetic ordering. We conclude that the
+small lattice anisotropy is insufficient to induce the in-plane electronic
+polarizability anisotropy necessary for the observed phonon intensity
+enhancement, and interpret this enhancement below the Neel temperature in terms
+of the anisotropy of the magnetic moment and magneto-elastic coupling. We
+evidence a Fano line- shape in the XY scattering geometry resulting from a
+strong coupling between the Ag (As) phonon mode and the B2g symmetry-like
+electronic continuum. Strong electron-phonon coupling may be relevant to
+superconductivity.",1712.01896v1
+2017-12-05,Third order perturbed modified Heisenberg Hamiltonian of fcc structured ferromagnetic films with seventy spin layers,"Magnetic properties of fcc structured ferromagnetic films with the number of
+spin layers up to seventy was described using third order perturbed Heisenberg
+Hamiltonian. The variation of magnetic easy direction, magnetic energies in
+easy and hard directions, magnetic anisotropy energy and the angle between easy
+and hard directions was investigated by varying the number of spin layers. Spin
+exchange interaction, magnetic dipole interaction, second and fourth order
+magnetic anisotropies, in and out of plane applied magnetic fields,
+demagnetization factor and stress induced anisotropy were considered in the
+model. Because magnetic dipole interaction and demagnetization factor represent
+microscopic and macroscopic properties of the sample, respectively, both these
+terms were incorporated in our theoretical model. Although our model is a
+semi-classical model, some discrete variations of angle of easy axis were
+observed. Our theoretical data qualitatively agree with experimental data of Fe
+and Ni ferromagnetic films.",1712.02636v1
+2017-12-15,Inplane anisotropy of longitudinal thermal conductivities and weak localization of magnons in a disordered spiral magnet,"We demonstrate the inplane anisotropy of longitudinal thermal conductivities
+and the weak localization of magnons in a disordered screw-type spiral magnet
+on a square lattice. We consider a disordered spin system, described by a spin
+Hamiltonian for the antiferromagnetic Heisenberg interaction and the
+Dzyaloshinsky-Moriya interaction with the mean-field type potential of
+impurities. We derive longitudinal thermal conductivities for the disordered
+screw-type spiral magnet in the weak-localization regime by using the
+linear-response theory with the linear-spin-wave approximation and performing
+perturbation calculations. We show that the inplane longitudinal thermal
+conductivities are anisotropic due to the Dzyaloshinsky-Moriya interaction.
+This anisotropy may be useful for experimentally estimating the magnitude of a
+ratio of the Dzyaloshinsky-Moriya interaction to the Heisenberg interaction. We
+also show that the main correction term gives a logarithmic suppression with
+the length scale due to the critical back scattering. This suggests that the
+weak localization of magnons is ubiquitous for the disordered two-dimensional
+magnets having global time-reversal symmetry. We finally discuss several
+implications for further research.",1712.05575v2
+2017-12-19,Measurements and atomistic theory of electron $g$ factor anisotropy for phosphorus donors in strained silicon,"This work reports the measurement of electron $g$ factor anisotropy ($|
+\Delta g |$ = $| g_{001} - g_{1 \bar 1 0} |$) for phosphorous donor qubits in
+strained silicon (sSi = Si/Si$_{1-x}$Ge$_x$) environments. Multi-million-atom
+tight-binding simulations are performed to understand the measured decrease in
+$| \Delta g |$ as a function of $x$, which is attributed to a reduction in the
+interface-related anisotropy. For $x <$7\%, the variation in $| \Delta g |$ is
+linear and can be described by $\eta_x x$, where $\eta_x \approx$1.62$\times$
+10$^{-3}$. At $x$=20\%, the measured $| \Delta g |$ is 1.2 $\pm$ 0.04 $\times$
+10$^{-3}$, which is in good agreement with the computed value of 1$\times
+10^{-3}$. When strain and electric fields are applied simultaneously, the
+strain effect is predicted to play a dominant role on $| \Delta g |$. Our
+results provide useful insights on spin properties of sSi:P for spin qubits,
+and more generally for devices in spintronics and valleytronics areas of
+research.",1712.06765v2
+2018-01-02,Parton self-energies for general momentum-space anisotropy,"We introduce an efficient general method for calculating the self-energies,
+collective modes, and dispersion relations of quarks and gluons in a
+momentum-anisotropic high-temperature quark-gluon plasma. The method introduced
+is applicable to the most general classes of deformed anisotropic momentum
+distributions and the resulting self-energies are expressed in terms of a
+series of hypergeometric basis functions which are valid in the entire complex
+phase-velocity plane. Comparing to direct numerical integration of the
+self-energies, the proposed method is orders of magnitude faster and provides
+results with similar or better accuracy. To extend previous studies and
+demonstrate the application of the proposed method, we present numerical
+results for the parton self-energies and dispersion relations of partonic
+collective excitations for the case of an ellipsoidal momentum-space
+anisotropy. Finally, we also present, for the first time, the gluon unstable
+mode growth rate for the case of an ellipsoidal momentum-space anisotropy.",1801.00863v2
+2018-01-03,Spin and mass superfluidity in ferromagnetic spin-1 Bose-Einstein condensate,"The paper investigates the coexistence and interplay of spin and mass
+superfluidity in a ferromagnetic spin-1 Bose-Einstein condensate. Superfluidity
+is possible only in the presence of uniaxial anisotropy (linear and quadratic
+Zeeman effect). This follows from the topology of the order-parameter space
+(vacuum manifold). According to the Landau criterion, the critical phase
+gradients, both for mass and spin supercurrents, vanish at the phase transition
+from the easy-plane to the easy-axis anisotropy. However, mass superfluidity is
+still possible at the phase transition. This is because the Landau criterion
+signals instability only with respect to nonsingular vortices with special
+ratio between circulations of mass and spin currents. Phase slips produced by
+these vortices are not sufficient for complete decay of supercurrents. Full
+decay of supercurrents requires phase slips with vortices of another
+topological class and larger energy. These phase slips are suppressed by
+energetic barriers up to the upper critical velocity (gradient) exceeding the
+Landau critical velocity. The upper critical velocity does not vanish nor has
+any anomaly in the critical point at the phase transition from the easy-plane
+to the easy-axis anisotropy.",1801.01099v2
+2018-01-12,Relativistic anisotropic stars with the polytropic equation of state in general relativity,"Spherically symmetric relativistic stars with the polytropic equation of
+state, which possess the local pressure anisotropy, are considered in the
+context of general relativity. The modified Lane-Emden equations are derived
+for the special ansatz for the anisotropy parameter $\Delta$ in the form of the
+differential relation between $\Delta$ and the metric function $\nu$. The
+analytical solutions of the obtained equations are found for incompressible
+fluid stars. The dynamical stability of incompressible anisotropic fluid stars
+against radial oscillations is studied.",1801.06958v2
+2018-01-26,Enhancement of exchange bias in ferromagnetic/antiferromagnetic core-shell nanoparticles through ferromagnetic domain wall formation,"The spin configuration in the ferromagnetic part during the magnetization
+reversal plays a crucial role in the exchange bias effect. Through Monte Carlo
+simulation, the exchange bias effect in ferromagnetic-antiferromagnetic
+core-shell nanoparticles is investigated. Magnetization reversals in the
+ferromagnetic core were controlled between the coherent rotation and the domain
+wall motion by modulating ferromagnetic domain wall width with parameters of
+uniaxial anisotropy constant and exchange coupling strength. An anomalous
+monotonic dependence of exchange bias on the uniaxial anisotropy constant is
+found in systems with small exchange coupling, showing an obvious violation of
+classic Meiklejohn-Bean model, while domain walls are found to form close to
+the interface and propagate in the ferromagnetic core with larger uniaxial
+anisotropy in both branches of the hysteresis. The asymmetric magnetization
+reversal with the formation of a spherical domain wall dramatically reduces the
+coercive field in the ascending branch, leading to the enhancement of the
+exchange bias. The results provide another degree of freedom to optimize the
+magnetic properties of magnetic nanoparticles for applications.",1801.08743v1
+2018-01-31,Finite-temperature dynamic structure factor of the spin-1 XXZ chain with single-ion anisotropy,"Improving matrix-product state techniques based on the purification of the
+density matrix, we are able to accurately calculate the finite-temperature
+dynamic response of the infinite spin-1 XXZ chain with single-ion anisotropy in
+the Haldane, large-$D$ and antiferromagnetic phases. Distinct thermally
+activated scattering processes make a significant contribution to the spectral
+weight in all cases. In the Haldane phase intraband magnon scattering is
+prominent, and the onsite anisotropy causes the magnon to split into singlet
+and doublet branches. In the large-$D$ phase response, the intraband signal is
+separated from an exciton-antiexciton continuum. In the antiferromagnetic
+phase, holons are the lowest-lying excitations, with a gap that closes at the
+transition to the Haldane state. At finite temperatures, scattering between
+domain-wall excitations becomes especially important and strongly enhances the
+spectral weight for momentum transfer $\pi$.",1801.10572v2
+2018-02-08,Direct observation of spin excitation anisotropy in the paramagnetic orthorhombic state of BaFe$_{2-x}$Ni$_x$As$_2$,"We use transport and inelastic neutron scattering measurements to investigate
+single crystals of iron pnictide BaFe$_{2-x}$Ni$_{x}$As$_{2}$ ($x=0,0.03$),
+which exhibit a tetragonal-to-orthorhombic structural transition at $T_s$ and
+stripe antiferromagnetic order at $T_N$ ($T_s\geq T_N$).
+  Using a tunable uniaxial pressure device, we detwin the crystals and study
+their transport and spin excitation properties at antiferromagnetic wave vector
+$S_1(1,0)$ and its 90$^\circ$ rotated wave vector $S_2(0,1)$ under different
+pressure conditions. We find that uniaxial pressure necessary to detwin and
+maintain single domain orthorhombic antiferromagnetic phase of
+BaFe$_{2-x}$Ni$_{x}$As$_{2}$ induces resistivity and spin excitation anisotropy
+at temperatures above zero pressure $T_s$. In uniaxial pressure-free detwinned
+sample, spin excitation anisotropy between $S_1(1,0)$ and $S_2(0,1)$ first
+appear in the paramagnetic orthorhombic phase below $T_s$. These results are
+consistent with predictions of spin nematic theory, suggesting the absence of
+structural or nematic phase transition above $T_s$ in iron pnictides.",1802.02713v1
+2018-02-12,On effects of inhomogeneity on anisotropy in Backus average,"In general, the Backus average of an inhomogeneous stack of isotropic layers
+is a transversely isotropic medium. Herein, we examine a relation between this
+inhomogeneity and the strength of resulting anisotropy, and show that, in
+general, they are proportional to one another. There is an important case,
+however, in which the Backus average of isotropic layers results in an
+isotropic -- as opposed to a transversely isotropic -- medium. We show that it
+is a consequence of the same rigidity of layers, regardless of their
+compressibility. Thus, in general, the strength of anisotropy of the Backus
+average increases with the degree of inhomogeneity among layers, except for the
+case in which all layers exhibit the same rigidity.",1802.04075v4
+2018-02-16,Anisotropies in the stochastic gravitational-wave background: Formalism and the cosmic string case,"We develop a powerful analytical formalism for calculating the energy density
+of the stochastic gravitational wave background, including a full description
+of its anisotropies. This is completely general, and can be applied to any
+astrophysical or cosmological source. As an example, we apply these tools to
+the case of a network of Nambu-Goto cosmic strings. We find that the angular
+spectrum of the anisotropies is relatively insensitive to the choice of model
+for the string network, but very sensitive to the value of the string tension
+$G\mu$.",1802.06046v4
+2018-02-19,Static properties and current-induced dynamics of pinned $90$ degree magnetic domain walls under applied fields: an analytic approach,"Magnetic domain walls are pinned strongly by abrupt changes in magnetic
+anisotropy. When driven into oscillation by a spin-polarized current, locally
+pinned domain walls can be exploited as tunable sources of short-wavelength
+spin waves. Here, we develop an analytical framework and discrete Heisenberg
+model to describe the static and dynamic properties of pinned domain walls with
+a head-to-tail magnetic structure. We focus on magnetic domain walls that are
+pinned by 90$^\circ$ rotations of uniaxial magnetic anisotropy. Our model
+captures the domain wall response to a spin-transfer torque that is exerted by
+an electric current. Model predictions of the domain wall resonance frequency
+and its evolution with magnetic anisotropy strength and external magnetic field
+are compared to micromagnetic simulations.",1802.06741v3
+2018-02-19,Borderline Magnetism: How Does Adding Magnesium to Paramagnetic CeCo$_3$ Make a 450 K Ferromagnet with Large Magnetic Anisotropy?,"A recent experimental study (Phys. Rev. Appl. 9, 024023, 2018) on
+paramagnetic CeCo$_3$ finds that Magnesium alloying induces a ferromagnetic
+transition with intrinsic properties large enough for permanent magnet
+applications. Here we explain these surprising results \textit{via} a first
+principles study of the electronic structure and magnetism of Magnesium-alloyed
+CeCo$_3$. We find the origin of this Magnesium-induced ferromagnetic transition
+to be Stoner physics - the substantial increase in the Fermi-level
+density-of-states $N(E_F)$ with Mg alloying. Our calculations suggest that both
+Ce and Co atoms are important for generating large magnetic anisotropy
+suggesting the viability of Co-3$d$, and Ce-4$f$ interaction for the generation
+of magnetic anisotropy in magnetic materials. These results offer a new route
+to the discovery of ferromagnetic materials and provide fundamental insight
+into the magnetic properties of these alloys",1802.06747v2
+2018-02-21,Phonon mode softening and elastic properties of hafnium under pressure,"The effect of pressure on the zone-center optical phonon modes and the
+elastic properties of hafnium has been studied by both experimental (Raman
+scattering) and theoretical (DFT) approaches. It was found an anomaly
+dependence of the phonon frequency of E$_{2g}$ mode in the pressure range from
+0 to 67 GPa. The calculated electronic structure of hafnium shows significant
+changes under pressure, which have a pronounced spatial anisotropy similar to
+the anisotropy of the observed phonon properties. The dependencies of the
+elastic properties on pressure including the components of the elasticity
+tensor, bulk and shear modulus, Poisson ratio and Universal anisotropy index
+obtained during the calculations has characteristic features indicating the
+occurrence of the structural phase transition.",1802.07531v1
+2018-02-25,Scaling Behavior of Anisotropy Relaxation in Deformed Polymers,"Drawing an analogy to the paradigm of quasi-elastic neutron scattering, we
+present a general approach for quantitatively investigating the spatiotemporal
+dependence of structural anisotropy relaxation in deformed polymers by using
+small-angle neutron scattering. Experiments and non-equilibrium molecular
+dynamics simulations on polymer melts over a wide range of molecular weights
+reveal that their conformational relaxation at relatively high momentum
+transfer $Q$ and short time can be described by a simple scaling law, with the
+relaxation rate proportional to $Q$. This peculiar scaling behavior, which
+cannot be derived from the classical Rouse and tube models, is indicative of a
+surprisingly weak direct influence of entanglement on the microscopic mechanism
+of single-chain anisotropy relaxation.",1802.09002v2
+2018-02-26,Relationship between Magnetic Anisotropy Below Pseudogap Temperature and Short-Range Antiferromagnetic Order in High-Temperature Cuprate Superconductor,"The central issue in high-temperature cuprate superconductors is the
+pseudogap state appearing below the pseudogap temperature $T^*$, which is well
+above the superconducting transition temperature. In this study, we
+theoretically investigate the rapid increase of the magnetic anisotropy below
+the pseudogap temperature detected by the recent torque-magnetometry
+measurements on YBa$_2$Cu$_3$O$_y$ [Y. Sato et al., Nat. Phys., 13, 1074
+(2017)]. Applying the spin Green's function formalism including the
+Dzyaloshinskii--Moriya interaction arising from the buckling of the CuO$_2$
+plane, we obtain results that are in good agreement with the experiment and
+find a scaling relationship. Our analysis suggests that the characteristic
+temperature associated with the magnetic anisotropy, which coincides with
+$T^*$, is not a phase transition temperature but a crossover temperature
+associated with the short-range antiferromagnetic order.",1802.09163v2
+2018-02-26,Elliptic flow from Coulomb interaction and low density elastic scattering,"In high energy heavy ion collisions and interacting cold atom systems, large
+elliptic flow anisotropies have been observed. For the large opacity
+($\rho\sigma L\sim 10^{3}$) of the latter hydrodynamics is a natural
+consequence, but for the small opacity ($\rho\sigma L\sim 1$) of the former
+hydrodynamic description is questionable. To shed light onto the situation, we
+simulate the expansion of a low density Argon ion (or atom) system, initially
+trapped in an elliptical region, under the Coulomb interaction (or elastic
+scattering). Significant elliptic anisotropy is found in both cases, and the
+anisotropy depends on the initial spatial eccentricity and the density of the
+system. The results may provide insights into the physics of anisotropic flow
+in high energy heavy ion collisions and its role in the study of quantum
+chromodynamics.",1802.09595v1
+2018-02-28,Voigt effect-based wide-field magneto-optical microscope integrated in a pump-probe experimental setup,"In this work we describe an experimental setup for spatially-resolved
+pump-probe experiment with integrated wide-field magneto-optical (MO)
+microscope. The MO microscope can be used to study ferromagnetic materials with
+both perpendicular-to-plane and in-plane magnetic anisotropy via polar Kerr and
+Voigt effects, respectively. The functionality of the Voigt effect-based
+microscope was tested using an in-plane magnetized ferromagnetic semiconductor
+(Ga,Mn)As. It was revealed that the presence of mechanical defects in the
+(Ga,Mn)As epilayer alters significantly the magnetic anisotropy in their
+proximity. The importance of MO experiments with simultaneous temporal and
+spatial resolutions was demonstrated using (Ga,Mn)As sample attached to a
+piezoelectric actuator, which produces a voltage-controlled strain. We observed
+a considerably different behavior in different parts of the sample that enabled
+us to identify sample parts where the epilayer magnetic anisotropy was
+significantly modified by a presence of the piezostressor and where it was not.
+Finally, we discuss the possible applicability of our experimental setup for
+the research of compensated antiferromagnets, where only MO effects even in
+magnetic moments are present.",1802.10534v1
+2018-03-07,Anisotropic electronic transport and Rashba effect of the two-dimensional electron system in (110) SrTiO$_3$-based heterostructures,"The two-dimensional electron system in (110)Al$_2$O$_{3-\delta}$/SrTiO$_3$
+heterostructures displays anisotropic electronic transport. Largest and lowest
+conductivity and electron mobility $\mu$ are observed along the $[001]$ and
+$[1\bar{1}0]$ direction, respectively. The anisotropy of the sheet resistance
+and $\mu$ likewise leads to a distinct anisotropic normal magnetotransport (MR)
+for T < 30K. However, at temperatures T<5K and magnetic field B<2T MR is
+dominated by weak antilocalization.Despite the rather strong anisotropy of the
+Fermi surfaces, the in-plane anisotropic magnetoresistance (AMR) displays
+two-fold non-crystalline anisotropy. However, the AMR-amplitude is found to be
+anisotropic with respect to the current direction, leading to a 60% larger AMR
+amplitude for current I along the $[001]$ direction compared to I parallel to
+$[1\bar{1}0]$. Tight binding calulations evidence an anisotropic Rashba-induced
+band splitting with dominant linear k-dependence. In combination with
+semiclassical Boltzmann theory the non-crystalline AMR is well described,
+despite the anisotropic Fermi surface.",1803.02646v1
+2018-03-12,Focused ion beam direct writing of magnetic patterns with controlled structural and magnetic properties,"Focused ion beam irradiation of metastable Fe$_{78}$Ni$_{22}$ thin films
+grown on Cu(100) substrates is used to create ferromagnetic,
+body-centered-cubic patterns embedded into paramagnetic, face-centered-cubic
+surrounding. The structural and magnetic phase transformation can be controlled
+by varying parameters of the transforming gallium ion beam. The focused ion
+beam parameters as ion dose, number of scans, and scanning direction can be
+used not only to control a degree of transformation, but also to change the
+otherwise four-fold in-plane magnetic anisotropy into the uniaxial anisotropy
+along specific crystallographic direction. This change is associated with a
+preferred growth of specific crystallographic domains. The possibility to
+create magnetic patterns with continuous magnetization transitions and at the
+same time to create patterns with periodical changes in magnetic anisotropy
+makes this system an ideal candidate for rapid prototyping of a large variety
+of nanostructured samples. Namely spin-wave waveguides and magnonic crystals
+can be easily combined into complex devices in a single fabrication step.",1803.04348v1
+2018-03-28,Primordial Anisotropies in the Gravitational Wave Background from Cosmological Phase Transitions,"Phase transitions in the early universe can readily create an observable
+stochastic gravitational wave background. We show that such a background
+necessarily contains anisotropies analogous to those of the cosmic microwave
+background (CMB) of photons, and that these too may be within reach of proposed
+gravitational wave detectors. Correlations within the gravitational wave
+anisotropies and their cross-correlations with the CMB can provide new insights
+into the mechanism underlying primordial fluctuations, such as multi-field
+inflation, as well as reveal the existence of non-standard ``hidden sectors"" of
+particle physics in earlier eras.",1803.10780v2
+2018-04-03,Raman Signatures of Broken Inversion Symmetry and In-plane Anisotropy in Type-II Weyl Semimetal Candidate TaIrTe4,"The layered ternary compound TaIrTe4 is an important candidate to host the
+recently predicted type-II Weyl Fermions. However, a direct and definitive
+proof of the absence of inversion symmetry in this material, a prerequisite for
+the existence of Weyl Fermions, has so far remained evasive. Herein, an
+unambiguous identification of the broken inversion symmetry in TaIrTe4 is
+established using angle-resolved polarized Raman spectroscopy. Combining with
+high-resolution transmission electron microscopy, we demonstrate an efficient
+and nondestructive recipe to determine the exact crystallographic orientation
+of TaIrTe4 crystals. Such technique could be extended to the fast
+identification and characterization of other type-II Weyl Fermions candidates.
+A surprisingly strong in-plane electrical anisotropy in TaIrTe4 thin flakes is
+also revealed, up to 200% at 10K, which is the strongest known electrical
+anisotropy for materials with comparable carrier density, notably in such good
+metals as copper and silver.",1804.00797v1
+2018-04-04,Emergence of topological Hall effect in half-metallic manganite thin films by tuning perpendicular magnetic anisotropy,"Magnetic materials hosting topological spin textures like magnetic skyrmion
+exhibit nontrivial Hall effect, namely, topological Hall effect (THE). In this
+study, we demonstrate the emergence of THE in thin films of half-metallic
+perovskite manganites. To stabilize magnetic skyrmions, we control the
+perpendicular magnetic anisotropy by imposing a compressive epitaxial strain as
+well as by introducing a small Ru doping. When the perpendicular magnetic
+anisotropy is tuned so that it is balanced with the magnetic dipolar
+interaction, the film exhibits a sizable THE in a magnetization reversal
+process. Real-space observations indicate the formation of skyrmions and some
+of them have high topological charge number. The present result opens up the
+possibility for novel functionalities that emerge under keen competition
+between the skyrmion phase and other rich phases of perovskite manganites with
+various orders in spin, charge, and orbital degrees of freedom.",1804.01425v2
+2018-04-09,Dislocation-induced thermal transport anisotropy in single-crystal group-III nitride films,"Dislocations, one-dimensional lattice imperfections, are common to
+technologically important materials such as III-V semiconductors, and adversely
+affect heat dissipation in e.g., nitride-based high-power electronic devices.
+For decades, conventional models based on nonlinear elasticity theory have
+predicted this thermal resistance is only appreciable when heat flux is
+perpendicular to the dislocations. However, this dislocation-induced
+anisotropic thermal transport has yet to be seen experimentally. In this study,
+we measure strong thermal transport anisotropy governed by highly oriented
+threading dislocation arrays along the cross-plane direction in micron-thick,
+single-crystal indium nitride (InN) films. We find that the cross-plane thermal
+conductivity is more than tenfold higher than the in-plane thermal conductivity
+at 80 K when the dislocation density is on the order of ~3x10^10 cm^-2. This
+large anisotropy is not predicted by the conventional models. With enhanced
+understanding of dislocation-phonon interactions, our results open new regimes
+for tailoring anisotropic thermal transport with line defects, and will
+facilitate novel methods for directed heat dissipation in thermal management of
+diverse device applications.",1804.02825v1
+2018-04-12,Anisotropic Superfluid Behavior of a Dipolar Bose-Einstein Condensate,"We present transport measurements on a dipolar superfluid using a
+Bose-Einstein condensate of Dy-162 with strong magnetic dipole-dipole
+interactions. By moving an attractive laser beam through the condensate we
+observe an anisotropy in superfluid flow. This observation is compatible with
+an anisotropic critical velocity for the breakdown of dissipationless flow,
+which, in the spirit of the Landau criterion, can directly be connected to the
+anisotropy of the underlying dipolar excitation spectrum. In addition, the
+heating rate above this critical velocity reflects the same anisotropy. Our
+observations are in excellent agreement with simulations based on the
+Gross-Pitaevskii equation and highlight the effect of dipolar interactions on
+macroscopic transport properties, rendering dissipation anisotropic.",1804.04552v2
+2018-04-16,Simulation study of elliptic flow of charged hadrons produced in Au + Au collisions at the Facility for Antiproton and Ion Research,"Centrality and system geometry dependence of azimuthal anisotropy of charged
+hadrons measured in terms of the elliptic flow parameter are investigated using
+Au+Au event samples at incident beam energy $20$A GeV and $40$A GeV generated
+by Ultrarelativistic Quantum Molecular Dynamics and A Multiphase Transport
+models. The Monte Carlo Glauber model is employed to estimate the eccentricity
+of the overlapping zone at an early stage of the collisions. Anisotropies
+present both in the particle multiplicity distribution and in the kinetic
+radial expansion are examined by using standard statistical and
+phenomenological methods. In the context of upcoming Compressed Baryonic Matter
+experiment to be held at the Facility for Antiproton and Ion Research, the
+present set of simulated results provide us not only with an opportunity to
+examine the expected collective behavior of hadronic matter at high baryon
+density and moderate temperature environment, but when compared with similar
+results obtained from Relativistic Heavy Ion Collider and Large Hadron Collider
+experiments, they also allow us to investigate how anisotropy of hadronic
+matter may differ or agree with its low baryon density and high temperature
+counterpart.",1804.05564v1
+2018-04-27,Size and shape of skyrmions for variable Dzyaloshinskii-Moriya interaction and uniaxial anisotropy,"We have performed micromagnetic simulations to study the formation of
+skyrmions in ferromagnetic elements with different shapes having perpendicular
+anisotropy. The strength of Dzyaloshinskii-Moriya interaction (D) and uniaxial
+anisotropy (K) are varied to elucidate the regime in which skyrmion formation
+can take place. It is found that for a certain combination of D and K skyrmion
+formation does not happen. Further we also observed that for large D and small
+K values, finite size effect dominates which in turn hinders formation of
+typical N'eel (spherical) skyrmions. However the resulting magnetic phase is
+skyrmionic in nature and has different shape. We also have found that the shape
+of the magnetic nano element has a significant role in determining the final
+magnetic state in addition to the competing D and K values.",1804.10548v1
+2018-05-01,On anisotropy of the maximum attainable speed of low-mass particles,"We evaluated the emission of a low-mass particle in the system (atomic)
+transition for the case when the particle Lorentz factor is $10^{18}$ and found
+that the angular distribution of emission in the laboratory inertial system is
+strongly affected by the directional variation of the maximum attainable speed
+of the particle. We show that for a photon mass consistent with the
+experimental limit, $m_{ph} \leq 10^{-18}$ eV, due to the experimentally known
+absence of a significant anisotropy of the photon emission by an atom, the
+anisotropy of the one-way speed of light, $\Delta c_1/c$, is $10^{-37}$ or
+less. This is many orders of magnitude smaller than previously reported and the
+limit becomes even stronger for the lower mass of the photon.",1805.00408v4
+2018-05-07,Anatomy of interfacial spin-orbit coupling in Co/Pd multilayers using X-ray magnetic circular dichroism and first-principles calculations,"Element-specific orbital magnetic moments and their anisotropies in
+perpendicularly magnetised Co/Pd multilayers are investigated using Co L-edge
+and Pd M-edge angle-dependent x-ray magnetic circular dichroism. We show that
+the orbital magnetic moments in Co are anisotropic, whereas those in Pd are
+isotropic. The first-principles density-functional-theory calculations also
+suggest that the Co/Pd interfacial orbital magnetic moments in Co are
+anisotropic and contribute to the perpendicular magnetic anisotropy (PMA), and
+that the isotropic ones in Pd manipulates the Co orbitals at the interface
+through proximity effects. Orbital-resolved anatomy of Co/Pd interfaces reveals
+that the orbital moment anisotropy in Co and spin-flipped transition related to
+the magnetic dipoles in Pd are essential for the appearance of PMA.",1805.02416v1
+2018-05-26,Ionic vs. van der Waals Layered Materials: Identification and Comparison of Elastic Anisotropy,"In this work, we expand the set of known layered compounds to include ionic
+layered materials, which are well known for superconducting, thermoelectric,
+and battery applications. Focusing on known ternary compounds from the ICSD, we
+screen for ionic layered structures by expanding upon our previously developed
+algorithm for identification of van der Waals (vdW) layered structures, thus
+identifying over 1,500 ionic layered compounds. Since vdW layered structures
+can be chemically mutated to form ionic layered structures, we have developed a
+methodology to structurally link binary vdW to ternary ionic layered materials.
+We perform an in-depth analysis of similarities and differences between these
+two classes of layered systems and assess the interplay between layer geometry
+and bond strength with a study of the elastic anisotropy. We observe a rich
+variety of anisotropic behavior in which the layering direction alone is not a
+simple predictor of elastic anisotropy. Our results enable discovery of new
+layered materials through intercalation or de- intercalation of vdW or ionic
+layered systems, respectively, as well as lay the groundwork for studies of
+anisotropic transport phenomena such as sound propagation or lattice thermal
+conductivity.",1805.10489v1
+2018-06-07,Strong and Tunable Spin Lifetime Anisotropy in Dual-Gated Bilayer Graphene,"We report the discovery of a strong and tunable spin lifetime anisotropy with
+excellent spin lifetimes up to 7.8 ns in dual-gated bilayer graphene.
+Remarkably, this realizes the manipulation of spins in graphene by
+electrically-controlled spin-orbit fields, which is unexpected due to
+graphene's weak intrinsic spin-orbit coupling. We utilize both the in-plane
+magnetic field Hanle precession and oblique Hanle precession measurements to
+directly compare the lifetimes of out-of-plane vs. in-plane spins. We find that
+near the charge neutrality point, the application of a perpendicular electric
+field opens a band gap and generates an out-of-plane spin-orbit field that
+stabilizes out-of-plane spins against spin relaxation, leading to a large spin
+lifetime anisotropy. This intriguing behavior occurs because of the unique
+spin-valley coupled band structure of bilayer graphene. Our results demonstrate
+the potential for highly tunable spintronic devices based on dual-gated 2D
+materials.",1806.02477v1
+2018-06-14,Molecular ordering of nematic liquid crystals in tubular nanopores: Tailoring of optical anisotropy at the nanoscale by polymer pore-surface grafting,"The optical polarimetry technique is used to explore molecular ordering of
+nematic liquid crystals 5FPFFPP3 embedded in parallel cylindrical channels of
+alumina membranes with pore walls covered by a SE-1211 polymer film enhancing
+normal anchoring. A chemical film deposition from organic solution apparently
+results in inhomogeneous coverage with local islands on the channels walls.
+Accordingly, a coexistence of differently ordered LC regions (nanodomains),
+characterized by positive and negative anisotropy, results in a weak effective
+(average) optical birefringence. Repeated polymer deposition reduces the size
+of uncovered pore walls regions and thus leads to a strengthening of negative
+optical anisotropy observed in the experiments.",1806.05630v2
+2018-06-29,Finsler space-time can explain both parity asymmetry and power deficit seen in CMB temperature anisotropies,"We propose a framework of Finsler space-time to explain the observed parity
+asymmetry and the power deficit in the low-$\ell$ ($2\leqslant \ell \leqslant
+29$) multipole range of cosmic microwave background (CMB) temperature
+anisotropies. In the $3+1$ dimensional space-time, the three-dimensional space
+is described by a Randers-Finsler space, which is spatially irreversible,
+inducing the parity asymmetry in the CMB angular power spectrum. We estimate
+the constraints on the two parameters introduced by Finsler space-time via
+analyzing the low-$\ell$ angular power spectrum in PLANCK 2015 CMB temperature
+data. We see that the low-$\ell$ power suppression in the CMB temperature
+anisotropies can also be resolved in this scenario. Our study shows that the
+two low-$\ell$ anomalies, i.e., parity asymmetry and power deficit, may have a
+common origin.",1806.11425v1
+2018-07-13,Gilbert damping of high anisotropy Co/Pt multilayers,"Using broadband ferromagnetic resonance, we measure the damping parameter of
+[Co(5 \r{A})/Pt(3 \r{A})]${\times 6}$ multilayers whose growth was optimized to
+maximize the perpendicular anisotropy. Structural characterizations indicate
+abrupt interfaces essentially free of intermixing despite the miscible
+character of Co and Pt. Gilbert damping parameters as low as 0.021 can be
+obtained despite a magneto-crystalline anisotropy as large as
+$10^6~\textrm{J/m}^3$. The inhomogeneous broadening accounts for part of the
+ferromagnetic resonance linewidth, indicating some structural disorder leading
+to a equivalent 20 mT of inhomogenity of the effective field. The unexpectedly
+relatively low damping factor indicates that the presence of the Pt heavy metal
+within the multilayer may not be detrimental to the damping provided that
+intermixing is avoided at the Co/Pt interfaces.",1807.04977v1
+2018-07-18,Multi-band effects in in-plane resistivity anisotropy of strain-detwinned disordered Ba(Fe$_{1-x}$Ru$_{x}$)$_{2}$As$_{2}$,"In-plane resistivity anisotropy was measured in strain-detwinned as-grown and
+partially annealed samples of isovalently-substituted
+$\mathrm{Ba(Fe_{1-x}Ru_{x})_{2}As_{2}}$ ($0<x \leq 0.125$) and the results were
+contrasted with previous reports on anneal samples with low residual
+resistivity. In samples with high residual resistivity, detwinned with
+application of strain, the difference of the two components of in-plane
+resistivity in the orthorhombic phase, $\rho_a -\rho_b$, was found to obey
+Matthiessen rule irrespective of sample composition, which is in stark contrast
+with observations on annealed samples. Our findings are consistent with
+two-band transport model in which contribution from high mobility carriers of
+small pockets of the Fermi surface has negligible anisotropy of residual
+resistivity and is eliminated by disorder. Our finding suggests that
+magnetic/nematic order has dramatically different effect on different parts of
+the Fermi surface. It predominantly affects inelastic scattering for small
+pocket high mobility carriers and elastic impurity scattering for larger sheets
+of the Fermi surface.",1807.07130v1
+2018-09-03,Confinement-induced Resonance of Alkaline-earth-metal-like Atoms in Anisotropic Quasi-one-dimensional Traps,"We study the confinement-induced resonance (CIR) of $^{173}$Yb atoms near an
+orbital Feshbach resonance in a quasi-one-dimensional tube with transversal
+anisotropy. By solving the two-body scattering problem, we obtain the location
+of CIR for various anisotropy ratio and magnetic field. Our results show that
+the anisotropy of the trapping potential can serve as an additional knob to
+tune the location of CIR. In particular, one can shift the location of CIR to
+the region attainable in current experiment. We also study the energy spectrum
+of the system and analyze the properties of CIR from the perspective of bound
+states. We find that as the orbital Feshbach resonance acquires two nearly
+degenerate scattering channels, which in general have different threshold
+energies, CIR takes place when the closed channel bound state energy becomes
+degenerate with one of the thresholds.",1809.00471v1
+2018-09-13,Anisotropic hybridization in a new Kondo lattice compound CeCoInGa$_3$,"We report a detailed and comparative study of the single crystal CeCoInGa$_3$
+in both experiment and theory. Resistivity measurements reveal the typical
+behavior of Kondo lattice with the onset temperature of coherence, $T^*\approx
+50\,$K. The magnetic specific heat can be well fitted using a spin-fluctuation
+model at low temperatures, yielding a large Sommerfeld coefficient,
+$\gamma\approx172\,$mJ/mol K$^2$ at 6 K, suggesting that this is a
+heavy-fermion compound with a pronounced coherence effect. The magnetic
+susceptibility exhibits a broad field-independent peak at $T_{\chi}$ and shows
+an obvious anisotropy within the $bc$ plane, reflecting the anisotropy of the
+coherence effect at high temperatures. These are compared with strongly
+correlated calculations combining first-principles band structure calculations
+and dynamical mean-field theory. Our results confirm the onset of coherence at
+about 50 K and reveal a similar anisotropy in the hybridization gap, pointing
+to a close connection between the hybridization strength of the low-temperature
+Fermi-liquid state and the high-temperature coherence effect.",1809.04735v1
+2018-10-10,Activity driven orientational order in active nematic liquid crystals on an anisotropic substrate,"We investigate the effect of an anisotropic substrate on the turbulent
+dynamics of a simulated two dimensional active nematic. This is introduced as
+an anisotropic friction and an effective anisotropic viscosity, with the
+orientation of the anisotropy being defined by the substrate. In this system we
+observe the emergence of global nematic order of topological defects that is
+controlled by the degree of anisotropy in the viscosity and the magnitude of
+the active stress. No global defect alignment is seen in passive liquid
+crystals with anisotropic viscosity or friction confirming that ordering is
+driven by the active stress. We then closely examine the active flow generated
+by a single defect to show that the kinetic energy of the flow is orientation
+dependent, resulting in a torque on the defect to align them with the
+anisotropy in the substrate.",1810.04549v1
+2018-10-12,Effectof biquadratic exchange on the phase diagram of a spin-1 transverse XY modelwith single-ion anisotropy,"The two-time Green function method is employed to explore the effect of the
+biquadratic exchange interaction on the phase diagram of a $d$-dimensional
+spin-1 transverse XY model with single-ion anisotropy close to the
+magnetic-field-induced quantum critical point. We work at level of the
+Anderson-Callen-decoupling-like framework for both easy-plane and easy-axis
+single-ion anisotropy. The structure of the phase diagram is analyzed with
+analytical estimates and numerical calculations by adopting Tyablikov-like
+decouplings for the exchange higher order Green functions in the equation of
+motion. For dominant bilinear short-range exchange interaction the structure of
+the phase diagram close to the quantum critical point remains qualitatively the
+same of that in absence of biquadratic interaction including reentrant critical
+lines. When the biquadratic exchange becomes increasingly dominant its role
+appears more effective and tends to reduce or destroy the reentrant character
+of the critical lines.",1810.05505v1
+2018-10-24,Nearly isotropic spin-pumping related Gilbert damping in Pt/Ni$_{81}$Fe$_{19}$/Pt,"A recent theory by Chen and Zhang [Phys. Rev. Lett. 114, 126602 (2015)]
+predicts strongly anisotropic damping due to interfacial spin-orbit coupling in
+ultrathin magnetic films. Interfacial Gilbert-type relaxation, due to the spin
+pumping effect, is predicted to be significantly larger for magnetization
+oriented parallel to compared with perpendicular to the film plane. Here, we
+have measured the anisotropy in the Pt/Ni$_{81}$Fe$_{19}$/Pt system via
+variable-frequency, swept-field ferromagnetic resonance (FMR). We find a very
+small anisotropy of enhanced Gilbert damping with sign opposite to the
+prediction from the Rashba effect at the FM/Pt interface. The results are
+contrary to the predicted anisotropy and suggest that a mechanism separate from
+Rashba spin-orbit coupling causes the rapid onset of spin-current absorption in
+Pt.",1810.10595v4
+2018-10-31,Angular momentum of fission fragments,"The strong deformation present immediately after scission has consequences
+for the angular momentum population of the fragments as well as the angular
+distribution of their decay radiation. We find that the usual spin-cutoff
+parameterization describes very well the angular momentum distribution
+associated with the deformation of the fragments at the scission point.
+Depending on the deformation, its contribution can comparable to the thermal
+contribution to the angular momentum of the newly formed fragments. The
+$M$-distribution of the angular momentum is highly polarized and gives rise to
+large anisotropies in the subsequent gamma cascade. We treat in detail a
+typical gamma cascade in a daughter nucleus, following usual model assumptions
+except for the anisotropy of the initial state. In principle, the observed
+anisotropy can provide information on the relative amounts of deformation and
+thermal energy present at the scission point.",1810.13429v1
+2018-11-02,Ferromagnetic ordering of linearly coordinated Co ions in LiSr$_2$[CoN$_2$],"LiSr$_2$[CoN$_2$] single crystals were successfully grown out of Li-rich
+flux. Temperature- and field-dependent measurements of the magnetization in the
+range of $T = 2 - 300$ K and up to $\mu_{0}\textit{H} = 7$ T as well as
+measurements of the heat capacity are presented. Ferromagnetic ordering emerges
+below $T_C = 44$ K and comparatively large coercivity fields of $\mu_0H = 0.3$
+T as well as pronounced anisotropy are observed upon cooling. Polycrystalline
+samples of the Ca analog LiCa$_2$[CoN$_2$] were obtained and investigated in a
+similar way. In both compounds Co manifests orbital contributions to the
+magnetic moment and large single-ion anisotropy that is caused by second-order
+Spin-orbit coupling. Quantum chemistry calculations reveal a magnetic
+anisotropy energy of 7 meV, twice as large as the values reported for similar
+Co $d^{8}$ systems.",1811.00867v1
+2018-12-14,Anisotropic magnetic properties and giant rotating magnetocaloric effect in double-perovskite Tb2CoMnO6,"We investigated the anisotropy of the magnetic and magnetocaloric properties
+of singlecrystalline double perovskite Tb2CoMnO6, which crystallizes in a
+monoclinic P21/n structure. Due to dissimilar magnetic anisotropy, the
+ferromagnetic order of the Co2+ and Mn4+ moments emerges along the c-axis at TC
+= 100 K, and the larger Tb3+ moments align perpendicular to the c-axis, below
+TTb = 15 K. The intricate temperature development of the metamagnetism along
+the c-axis results in a large negative change in the magnetic entropy at low
+temperature. On the other hand, the larger but almost reversible magnetization,
+perpendicular to the c-axis, results in a small and positive entropy change.
+This highly anisotropic magnetocaloric effect (MCE) leads to a giant rotational
+MCE, estimated to be 20.8 J/kg K. Our findings, based on the magnetic
+anisotropy in Tb2CoMnO6, enrich fundamental and applied research on magnetic
+materials, considering the distinct magnetic characteristics of double
+perovskites.",1812.05798v1
+2018-12-28,Anisotropy in 2D Discrete Exterior Calculus,"We present a local formulation for 2D Discrete Exterior Calculus (DEC)
+similar to that of the Finite Element Method (FEM), which allows a natural
+treatment of material heterogeneity (element by element). It also allows us to
+deduce, in a robust manner, anisotropic fluxes and the DEC discretization of
+the pullback of 1-forms by the anisotropy tensor, i.e. we deduce how the
+anisotropy tensor acts on primal 1-forms. Due to the local formulation, the
+computational cost of DEC is similar to that of the Finite Element Method with
+Linear interpolations functions (FEML). The numerical DEC solutions to the
+anisotropic Poisson equation show numerical convergence, are very close to
+those of FEML on fine meshes and are slightly better than those of FEML on
+coarse meshes.",1812.11155v1
+2019-01-03,Realization of Kondo chain in CeCo$_2$Ga$_8$,"We revisited the anisotropy of the heavy-fermion material CeCo$_2$Ga$_8$ by
+measuring the electrical resistivity and magnetic susceptibility along all the
+principal $\mathbf{a}$-, $\mathbf{b}$- and $\mathbf{c}$-axes. Resistivity along
+$\mathbf{c}$-axis ($\rho_c$) shows clear Kondo coherence below about 17 K,
+while both $\rho_{a}$ and $\rho_{b}$ remain incoherent down to 2 K. The
+magnetic anisotropy is well understood within the theoretical frame of
+crystalline electric field effect in combination with magnetic exchange
+interactions. We found the anisotropy ratio of these magnetic exchange
+interactions, $|J_{ex}^c/J_{ex}^{a,b}|$, reaches a large value of 4-5. We,
+therefore, firmly demonstrate that CeCo$_2$Ga$_8$ is a quasi-one-dimensional
+heavy-fermion compound both electrically and magnetically, and thus provide a
+realistic example of \textit{Kondo chain}.",1901.00558v2
+2019-01-07,Giant anisotropy of Gilbert damping in epitaxial CoFe films,"Tailoring Gilbert damping of metallic ferromagnetic thin films is one of the
+central interests in spintronics applications. Here we report a giant Gilbert
+damping anisotropy in epitaxial Co$_{50}$Fe$_{50}$ thin film with a
+maximum-minimum damping ratio of 400 \%, determined by broadband spin-torque as
+well as inductive ferromagnetic resonance. We conclude that the origin of this
+damping anisotropy is the variation of the spin orbit coupling for different
+magnetization orientations in the cubic lattice, which is further corroborate
+from the magnitude of the anisotropic magnetoresistance in Co$_{50}$Fe$_{50}$.",1901.01941v1
+2019-01-15,Effect of random anisotropy on NMR frequency shift in the polar phase of the superfluid 3He,"The orbital anisotropy induced in the superfluid 3He by nematic aerogel is,
+generally speaking, spatially non-uniform. This anisotropy in its turn induces
+spatial fluctuations of the order parameter. It is shown here that for the
+polar phase these fluctuations decrease the overall amplitude of the order
+parameter and the value of the frequency shift of the transverse NMR. Different
+contributions to this effect are discussed and estimated. Their temperature
+dependencies are discssed as well.",1901.05025v2
+2019-01-18,Ballistic transport experiment detects Fermi surface anisotropy of graphene,"Monolayer graphene and bilayer graphene have strikingly different properties.
+One such difference is the shape of the Fermi surface. Although anisotropic
+band structures can be detected in optical measurements, they have so far been
+difficult to detect in transport experiments on twodimensional materials. Here
+we describe a ballistic transport experiment using high-quality graphene that
+revealed Fermi surface anisotropy in the magnetoresistance. The shape of the
+Fermi surface is closely related with the cyclotron orbit in real space.
+Electron trajectories in samples with triangular lattices of holes depend on
+the anisotropy of the Fermi surface. We found that this results in the
+magnetoresistance which are dependent on crystallographic orientation of the
+antidot lattice, which indicates the anisotropic Fermi surface of bilayer
+graphene which is a trigonally-warped circle in shape. While in monolayer,
+shape of magnetoresistance was approximately independent of the orientation of
+antidot lattice, which indicates that the Fermi surface is a circle in shape.
+The ballistic transport experiment is a new method of detecting anisotropic
+electronic band structures in two-dimensional electron systems.",1901.06073v1
+2019-02-02,Propagation of UHECRs in the local Universe and origin of cosmic magnetic fields,"We simulate the propagation of cosmic rays at ultra-high energies, $\gtrsim
+10^{18}$ eV, in models of extragalactic magnetic fields in constrained
+simulations of the local Universe. We investigate the impact of different
+magneto-genesis scenarios, both, primordial and astrophysical, on the
+propagation of cosmic rays. Our study shows that different scenarios of
+magneto-genesis do not have a large impact on the anisotropy measurements. The
+distribution of nearby sources causes anisotropy at very high energies,
+independent of the magnetic field model. We compare our results to the dipole
+signal measured by the Pierre Auger Observatory. All our models could reproduce
+the observed dipole amplitude with a pure iron injection composition. This is
+due to clustering of secondary nuclei in direction of nearby sources of heavy
+nuclei. A light injection composition is disfavoured by the non-observation of
+anisotropy at energies of 4 - 8 EeV.",1902.04408v1
+2019-02-12,Characterization of spin wave propagation in (111) YIG thin films with large anisotropy,"We report on long-range spin wave (SW) propagation in nanometer-thick yttrium
+iron garnet (YIG) film with an ultralow Gilbert damping. The knowledge of a
+wavenumber value $|\vec{k}|$ is essential for designing SW devices. Although
+determining the wavenumber $|\vec{k}|$ in experiments like Brillouin light
+scattering spectroscopy is straightforward, quantifying the wavenumber in
+all-electrical experiments has not been widely commented upon so far. We
+analyze magnetostatic spin wave (SW) propagation in YIG films in order to
+determine the SW wavenumber $|\vec{k}|$ excited by the coplanar waveguide. We
+show that it is crucial to consider the influence of magnetic anisotropy fields
+present in YIG thin films for precise determination of SW wavenumber. With the
+proposed methods we find that experimentally derived values of $|\vec{k}|$ are
+in perfect agreement with that obtained from electromagnetic simulation only if
+anisotropy fields are included.",1902.04608v1
+2019-02-25,Magic Numbers for the Photoelectron Anisotropy in Li-Doped Dimethyl Ether Clusters,"Photoelectron velocity map imaging of Li(CH$_3$OCH$_3$)$_n$ clusters (1
+$\leq$ n $\leq$ 175) is used to search for magic numbers related to the
+photoelectron anisotropy. Comparison with density functional calculations
+reveals magic numbers at n=4, 5, and 6, resulting from the symmetric charge
+distribution with high s-character of the highest occupied molecular orbital.
+Since each of these three cluster sizes correspond to the completion of a first
+coordination shell, they can be considered as 'isomeric motifs of the first
+coordination shell'. Differences in the photoelectron anisotropy, the vertical
+ionization energies and the enthalpies of vaporization between
+Li(CH$_3$OCH$_3$)$_n$ and Na(CH$_3$OCH$_3$)$_n$ can be rationalized in terms of
+differences in their solvation shells, atomic ionization energies,
+polarizabilities, metal-oxygen bonds, ligand-ligand interactions, and by
+cooperative effects.",1902.09575v1
+2019-03-12,Neutron Diffraction Studies on Temperature Driven Crystallographic Anisotropy in FeVO4 Multiferroic: Evidence of Strong Magnetostructural Correlations,"We used temperature-dependent neutron diffraction measurements on FeVO4 to
+understand the temperature driven anisotropy and observed that the maximum
+change for a and b lattice parameters in conjunction with a large contraction
+in angle \beta\ as a function of temperature. The least changes are observed
+for the c lattice parameter and in \gamma\ angle. From these structural
+parameters, it can be said that, FeVO4 exhibits large structural anisotropy
+with lowering temperature. The large change in lattice parameters in magnetic
+phases i.e. below 22 K explains the strong magnetostructural coupling in FeVO4.",1903.04913v1
+2019-03-12,The tidal deformability of an anisotropic compact star: Implications of GW170817,"We use gravitational wave (GW) and electromagnetic (EM) observations of
+GW170817 to constrain the extent of pressure anisotropy in it. While it is
+quite likely that the pressure inside a neutron star is mostly isotropic,
+certain physical processes or characteristics, such as phase transitions in
+nuclear matter or the presence of strong magnetic fields, can introduce
+pressure anisotropy. In this work, we show that anisotropic pressure in neutron
+stars can reduce their tidal deformability substantially. For the
+anisotropy-pressure model of Bowers and Liang and a couple of relativistic EOSs
+-- DDH$\delta$ and GM1 -- we demonstrate that this reduction in spherical
+neutron stars with masses in the range of 1 to 2 $M_\odot$ can be 23% to 46%.
+This suggests that certain EOSs that are ruled out by GW170817 observations,
+under assumptions of pressure isotropy, can become viable if the stars had a
+significant enough anisotropic pressure component, but do not violate
+causality. We also show how the inference of the star radius can be used to
+rule out certain EOSs (such as GM1), even for high anisotropic pressure,
+because their radii are larger than what the observations find.",1903.04956v1
+2019-03-14,In-plane anisotropic faceting of ultralarge and thin single-crystalline colloidal SnS nanosheets,"The colloidal synthesis of large thin two-dimensional (2D) nanosheets is
+fascinating but challenging, since the growth along the lateral and vertical
+dimensions need to be controlled independently. In-plane anisotropy in 2D
+nanosheets is attracting more attention as well. We present a new synthesis for
+large colloidal single-crystalline SnS nanosheets with the thicknesses down to
+7 nm and lateral sizes up to 8 um. The synthesis uses trioctylphosphine-S
+(TOP-S) as sulfur source and oleic acid (with or without TOP) as ligands. Upon
+adjusting the capping ligand amount, the growth direction can be switched
+between anisotropic directions (armchair and zigzag) and isotropic directions
+(""ladder"" directions), leading to an edge-morphology anisotropy. This is the
+first report on solution-phase synthesis of large thin SnS NSs with tunable
+edge faceting. Furthermore, electronic transport measurements show strong
+dependency on the crystallographic directions confirming structural anisotropy.",1903.06062v1
+2019-03-21,Magnetic and electrical anisotropy with correlation and orbital effects in dimerized honeycomb ruthenate Li$_2$RuO$_3$,"Li2RuO3 undergoes a structural transition at a relatively high temperature of
+550 K with a distinct dimerization of Ru-Ru bonds on the otherwise isotropic
+honeycomb lattice. It exhibits a unique herringbone dimerization pattern with a
+largest ever reported value of the bond shrinkage of about ~ 0.5 \r{A}. Despite
+extensive studies, both theoretical and experimental, however, its origin and
+its effect on physical properties still remain to be understood. In this work,
+using high quality single crystals we investigated the anisotropy of
+resistivity ($\rho$) and magnetic susceptibility ($\chi$) to find a very clear
+anisotropy: $\rho$$_c*$ > $\rho$$_b$ > $\rho$$_a$ and $\chi$$_b$ > $\chi$$_a$ >
+$\chi$$_c*$. For possible theoretical interpretations, we carried out density
+functional calculations to conclude that these anisotropic behavior is due to
+the correlation effects combined with the unique orbital structure and the
+dimerization of Ru 4d bands.",1903.08812v2
+2019-04-01,An all-electron product-basis set: application to plasmon anisotropy in simple metals,"An efficient basis set for products of all-electron wave functions is
+proposed, which comprises plane waves defined over the entire unit cell and
+orbitals confined to small non-overlapping spheres. The size of the set and the
+basis functions are, in principle, independent of the computational parameters
+of the band structure method. The approach is implemented in the extended LAPW
+method, and its properties and accuracy are discussed. The method is applied to
+analyze the dielectric response of the simple metals Al, Na, Li, K, Rb, and Cs
+with a focus on the origin of the anisotropy of the plasmon dispersion in Al
+and Na. The anisotropy is traced to tiny structures of the one-particle
+excitation spectra of Al and Na, and relevant experimental observations are
+explained.",1904.00968v1
+2019-04-08,Spectral anisotropies and intermittency of plasma turbulence at ion kinetic scales,"By means of three dimensional high-resolution hybrid simulations we study the
+properties of the magnetic field spectral anisotropies near and beyond ion
+kinetic scales. By using both a Fourier analysis and a local analysis based on
+multi-point 2nd-order structure function techniques, we show that the
+anisotropy observed is less than what expected by standard wave normal modes
+turbulence theories although the non linear energy transfer is still in the
+perpendicular direction, only advected in the parallel direction as expected
+balancing the non-linear energy transfer time and the decorrelation time. Such
+result can be explained by a phenomenological model based on the formation of
+strong intermittent two-dimensional structures in the plane perpendicular to
+the local mean field that have some prescribed aspect ratio eventually
+depending on the scale. This model support the idea that small scales
+structures, such as reconnecting current sheets, contribute significantly to
+the formation of the turbulent cascade at kinetic scales.",1904.03903v2
+2019-04-09,Large effect of the metal substrate on the magnetic anisotropy of Co on hexagonal Boron Nitride,"We combine x-ray absorption spectroscopy (XAS), x-ray magnetic circular
+dichroism (XMCD) and x-ray magnetic linear dichroism (XMLD) data with first
+principles density functional theory (DFT) calculations and a multiorbital many
+body Hamiltonian approach to understand the electronic and magnetic properties
+of Co atoms adsorbed on h-BN/Ru(0001) and h-BN/Ir(111). The XAS line shape
+reveals, for both substrates, an electronic configuration close to $3d^8$,
+corresponding to a spin $S = 1$. Magnetic field dependent XMCD data show large
+(14 meV) out-of-plane anisotropy on h-BN/Ru(0001), while it is almost isotropic
+(tens of $\mu$eV) on h-BN/Ir(111). XMLD data together with both DFT
+calculations and the results of the multiorbital Hubbard model suggest that the
+dissimilar magnetic anisotropy originates from different Co adsorption sites,
+namely atop N on h-BN/Ru(0001) and 6-fold hollow on h-BN/Ir(111).",1904.04738v1
+2019-04-16,Properties of the stochastic astrophysical gravitational wave background: astrophysical sources dependencies,"This article explores the properties (amplitude and shape) of the angular
+power spectrum of the anisotropies of the astrophysical gravitational wave
+background (AGWB) focusing on the signatures of the astrophysical models
+describing sub-galactic physics. It demonstrates that while some parameters
+have negligible impact others, and in particular the stellar evolution models,
+the metallicity and the merger time delay distribution can result in relative
+differences of order 40% in the angular power spectrum of anisotropies in both
+the LIGO/Virgo and LISA frequency bands. It is also shown that the monopole and
+the anisotropic components of the AGWB are complementary and sensitive to
+different astrophysical parameters. It follows that AGWB anisotropies are a new
+observable with the potential to provide new astrophysical information that can
+not be accessed otherwise.",1904.07797v3
+2019-04-19,Sub-terahertz ferrimagnetic spin-transfer torque oscillator,"A theory of magnetization dynamics in ferrimagnetic materials with
+antiparallel aligned spin sub-lattices under action of spin-transfer torques
+(STT) is developed. We consider magnetization dynamics in GdFeCo layers in two
+cases of magnetic anisotropy: easy plane and easy axis. We demonstrate that,
+(i) for the easy plane anisotropy the precession of the N\'{e}el vector is
+conical and the cone angle depends on the STT strength and the value of spin
+non-compensation, while the frequency of precession can reach sub-THz
+frequencies; (ii) for the easy axis anisotropy two regimes are possible:
+deterministic switching of the net magnetization and a conical sub-THz
+precession depending on the STT strength.",1904.09341v1
+2019-04-30,Dynamics of a magnetic skyrmionium in an anisotropy gradient,"Magnetic skyrmionium is a novel magnetization configuration with zero
+skyrmion number, which is composed by two skyrmions with opposite skyrmion
+number. Here, we study the dynamics of skyrmionium under an anisotropy
+gradient. We find that the skyrmionium can be efficiently driven by an
+anisotropy gradient with moving straightly along the direction of gradient. The
+skyrmion Hall angle for skyrmionium is close to zero which is much smaller than
+that of skyrmion. while the speed is much larger. We also demonstrate that the
+skyrmionium motion depends on the damping cofficient, and the skyrmionium
+stabilization in the motion can be modulated by narrowing the width of the
+nanowire. Our work shows a efficient driven method for skyrmionium, which may
+be promising in the application of skyrmionium based racetrack memory.",1904.13332v1
+2019-05-06,Probing cosmic anisotropy with GW/FRB as upgraded standard sirens,"Recently it was shown that cosmic anisotropy can be well tested using either
+standard siren measurement of luminosity distance $d_\mathrm{L}(z)$ from
+gravitational-wave (GW) observation or dispersion measure ($\mathrm{DM}(z)$)
+from fast radio burst (FRB). It was also observed that the combined measurement
+of $d_\mathrm{L}(z)\cdot\mathrm{DM}(z)$ from the GW/FRB association system as
+suggested in some of FRB models is more effective to constrain cosmological
+parameters than $d_\mathrm{L}(z)$ or $\mathrm{DM}(z)$ separately due to its
+independence from Hubble constant. In this paper, we will show both
+theoretically and with simulation that, this upgraded sirens from combined
+GW/FRB observations could test cosmic anisotropy with a double relative
+sensitivity compared to the usual standard siren from GW observation alone.",1905.01803v2
+2019-05-10,Long-wavelength emergent phonons in skyrmion crystals distorted by exchange anisotropy and tilted magnetic fields,"Skyrmion crystals (SkX) are periodic alignment of magnetic skyrmions, i.e., a
+type of topologically protected spin textures. Compared with ordinary crystals,
+they can be drastically deformed under anisotropic effects because they are
+composed of field patterns whose deformation does not cause any bond-breaking.
+This exotic ductility of SkX bring about great tunability of its collective
+excitations called emergent phonons, which are vital for magnonics application.
+The question is how to quantitatively determine the emergent phonons of
+distorted SkX. Here we systematically study the long wavelength emergent
+phonons of SkX distorted by (a) a negative exchange anisotropy, and (b) a
+tilted magnetic field. In both cases, deformation and structural transitions of
+SkX thoroughly influence the frequency, anisotropy of vibrational pattern and
+dispersion relation, and coupling between lattice vibration and in-lattice
+vibration for all modes. Tilted magnetic fields are very effective in tuning
+the emergent phonons, such that all modes except the Goldstone mode can be
+excited by AC magnetic fields when a tilted bias field is presented.",1905.03987v1
+2019-05-08,Hidden Anisotropy in the Drude Conductivity of Charge Carriers with Dirac-Schrödinger Dynamics,"We show that the conductivity of a two-dimensional electron gas can be
+intrinsically anisotropic despite isotropic Fermi surface, energy dispersion,
+and disorder configuration. In the model we study, the anisotropy stems from
+the interplay between Dirac and Schr\""odinger features combined in a special
+two-band Hamiltonian describing the quasiparticles similar to the low-energy
+excitations in phosphorene. As a result, even scalar isotropic disorder
+scattering alters the nature of the carriers and results in anisotropic
+transport. Solving the Boltzmann equation exactly for such carriers with
+point-like random impurities we find a hidden knob to control the anisotropy
+just by tuning either the Fermi energy or temperature. Our results are expected
+to be generally applicable beyond the model studied here, and should stimulate
+further search for the alternative ways to control electron transport in
+advanced materials.",1905.04292v1
+2019-05-20,Anisotropy engineering edge magnetism in zigzag honeycomb nanoribbons,"It have been demonstrated that the zigzag honeycomb nanoribbons exhibit an
+intriguing edge magnetism. Here the effect of the anisotropy on the edge
+magnetism in zigzag honeycomb nanoribbons is investigated by using two kinds of
+large-scale quantum Monte Carlo simulations. The anisotropy in zigzag honeycomb
+nanoribbons is characterized by the ratios of nearest-neighboring hopping
+integrals $t_{1}$ in one direction and $t_{2}$ in another direction.
+Considering the electron-electron correlation, it is shown that the edge
+ferromagnetism could be enhanced greatly as $t_{2}/|t_{1}|$ increase from $1$
+to $3$, which not only presenting the avenue for the control of this magnetism,
+but also being useful for exploring further novel magnetism in new nano-scale
+materials.",1905.08050v1
+2019-05-20,Density jump as a function of magnetic field for collisionless shocks in pair plasmas: the perpendicular case,"In the absence of frequent binary collisions to isotropize the plasma, the
+fulfillment of the magnetohydrodynamic (MHD) Rankine-Hugoniot jump conditions
+by collisionless shocks is not trivial. In particular, the presence of an
+external magnetic field can allow for stable anisotropies, implying some
+departures from the isotropic MHD jumps. The functional dependence of such
+anisotropies in terms of the field is yet to be determined. By hypothesizing a
+kinetic history of the plasma through the shock front, we recently devised a
+theory of the downstream anisotropy, hence of the density jump, in terms of the
+field strength for a parallel shock [J. Plasma Phys. (2018), vol. 84,
+905840604]. Here, we extend the analysis to the case of a perpendicular shock.
+We still find that the field reduces the density jump, but the effect is less
+pronounced than in the parallel case.",1905.08079v1
+2019-05-28,Sensitivity of D meson azimuthal anisotropies to system size and nuclear structure,"Recent experimental data at the Large Hadron Collider (LHC) confirmed that
+the soft sector azimuthal anisotropies in central XeXe collisions are sensitive
+to deformations in the wave function of the Xenon nucleus. Additionally, the
+CMS experiment found that D meson flow is slightly suppressed compared to other
+particle species when considering quark number scaling in small systems of pPb
+compared to PbPb. In this talk we used the D and B Mesons Modular (DAB-MOD)
+code coupled to Trento+v-USPhydro to calculate the $R_{AA}$ and $v_n$'s of D
+mesons using different energy loss models and Langevin techniques. Comparing D
+mesons $R_{AA}$ and $v_n$ in PbPb to XeXe collisions it is found that in
+central collisions D meson azimuthal anisotropies are sensitive to details in
+the nuclear structure wave function of Xenon. Additionally, we find that in
+mid-central collisions the smaller system size of XeXe suppresses D meson flow.",1905.12038v1
+2019-06-01,"Theory of skyrmion, meron, anti-skyrmion and anti-meron in chiral magnets","We find closed-form solution of the Euler equation for a chiral magnet in
+terms of a skyrmion or a meron depending on the relative strengths of magnetic
+anisotropy and magnetic field. We show that the relevant length scales for
+these solutions primarily depend on the strengths of Dzyaloshinskii-Moriya
+interaction through its ratios, respectively, with magnetic field and magnetic
+anisotropy. We thus unambiguously determine the parameter dependencies on the
+radius of the topological structures particularly of the skyrmions, showing an
+excellent agreement with experiments and first-principle studies. An
+anisotropic Dzyaloshinskii-Moriya interaction suitable for thin films made with
+$C_{nv}$ symmetric materials is found to stabilize anti-skyrmion and
+anti-meron, which are prototypical for $D_{2d}$ symmetric systems, depending on
+the degree of anisotropy. Based on these solutions, we obtain phase diagram by
+comparing the energies of various collinear and non-collinear competing phases.",1906.00210v2
+2019-06-03,Induced Charge Anisotropy: a Hidden Variable Affecting Ion Transport through Membranes,"The ability of semipermeable membranes to selectively impede the transport of
+undesirable solutes is key to many applications. Yet, obtaining a systematic
+understanding of how membrane structure affects selectivity remains elusive due
+to the insufficient spatiotemporal resolution of existing experimental
+techniques, and the inaccessibility of relevant solute transport timescales to
+conventional molecular simulations. Here, we utilize jumpy forward-flux
+sampling to probe the transport of sodium and chloride ions through a graphitic
+membrane with sub-nm pores. We find chlorides to traverse the pore at rates
+over two orders of magnitude faster than sodiums. We also identify two major
+impediments to the transport of both ion types. In addition to the partial
+dehydration of the leading ion, its traversal induces charge anisotropy at its
+rear, which exerts a net restraining force on the ion. Charge anisotropy is
+therefore a crucial hidden variable controlling the kinetics of ion transport
+through nanopores.",1906.00853v2
+2019-06-07,Shear-Induced Anisotropy in Rough Elastomer Contact,"True contact between randomly rough solids consists of myriad individual
+micro-junctions. While their total area controls the adhesive friction force of
+the interface, other macroscopic features, including viscoelastic friction,
+wear, stiffness and electric resistance, also strongly depend on the size and
+shape of individual micro-junctions. Here we show that, in rough elastomer
+contacts, the shape of micro-junctions significantly varies as a function of
+the shear force applied to the interface. This process leads to a growth of
+anisotropy of the overall contact interface, which saturates in macroscopic
+sliding regime. We show that smooth sphere/plane contacts have the same
+shear-induced anisotropic behaviour as individual micro-junctions, with a
+common scaling law over four orders of magnitude in initial area. We discuss
+the physical origin of the observations in the light of a fracture-based
+adhesive contact mechanics model, described in the companion article, which
+captures the smooth sphere/plane measurements. Our results shed light on a
+generic, overlooked source of anisotropy in rough elastic contacts, not taken
+into account in current rough contact mechanics models.",1906.02947v1
+2019-06-10,Formation of spiral ordering by magnetic field in frustrated anisotropic antiferromagnets,"We discuss theoretically phase transitions in frustrated antiferromagnets
+with biaxial anisotropy or dipolar forces in magnetic field applied along the
+easy axis at $T=0$. There are well-known sequences of phase transitions upon
+the field increasing: the conventional spin-flop transition and the flop of the
+spiral plane at strong and weak easy-axis anisotropy, respectively. We argue
+that much less studied scenarios can appear at moderate anisotropy in which the
+magnetic field induces transitions of the first order from the collinear state
+to phases with spiral orderings. Critical fields of these transitions are
+derived in the mean-field approximation and the necessary conditions are found
+for the realization of these scenarios. We show that one of the considered
+sequences of phase transitions was found in multiferroic MnWO$_4$ both
+experimentally and numerically (in a relevant model) and our theory reproduces
+quantitatively the numerical findings.",1906.03839v2
+2019-06-12,Perfect control of photoelectron anisotropy for randomly oriented ensembles of molecules by XUV REMPI and polarization shaping,"We report two schemes to generate perfect anisotropy in the photoelectron
+angular distribution of a randomly oriented ensemble of polyatomic molecules.
+In order to exert full control over the anisotropy of photoelectron emission,
+we exploit interferences between single-photon pathways and a manifold of
+resonantly-enhanced two-photon pathways. These are shown to outperform
+non-sequential $(\omega,2\omega)$ bichromatic phase control for the example of
+CHFClBr molecules. We are able to optimize pulses that yield anisotropic
+photoelectron emission thanks to a very efficient calculation of photoelectron
+momentum distributions. This is accomplished by combining elements of quantum
+chemistry, variational scattering theory, and time-dependent perturbation
+theory.",1906.05207v1
+2019-06-13,Thermal Creation of Skyrmions in Ferromagnetic Films with Perpendicular Anisotropy and Dzyaloshinskii-Moriya Interaction,"We study theoretically, via Monte Carlo simulations on lattices containing up
+to 1000 x 1000 spins, thermal creation of skyrmion lattices in a 2D
+ferromagnetic film with perpendicular magnetic anisotropy and
+Dzyaloshinskii-Moriya interaction. At zero temperature, skyrmions only appear
+in the magnetization process in the presence of static disorder. Thermal
+fluctuations violate conservation of the topological charge and reduce the
+effective magnetic anisotropy that tends to suppress skyrmions. In accordance
+with recent experiments, we find that elevated temperatures assist the
+formation of skyrmion structures. Once such a structure is formed, it can be
+frozen into a regular skyrmion lattice by reducing the temperature. We
+investigate topological properties of skyrmion structures and find the average
+skyrmion size. Energies of domain and skyrmion states are computed. It is shown
+that skyrmion lattices have lower energy than labyrinth domains within a narrow
+field range.",1906.05952v1
+2019-06-17,Searching for Fossil Fields in the Gravity Sector,"Evidence for the presence of extra fields during inflation may be found in
+the anisotropies of the scalar and tensor spectra across a vast range of
+scales. Indeed, beyond the single-field slow-roll paradigm, a long tensor mode
+can modulate the power spectrum inducing a sizable quadrupolar anisotropy. We
+investigate how this dynamics plays out for the tensor two-point correlator.
+The resulting quadrupole stores information on squeezed tensor
+non-Gaussianities, specifically those sourced by the extra field content and
+responsible for the breaking of so-called consistency relations. We underscore
+the potential of anisotropies as a probe of new physics: testable at CMB scales
+through the detection of B-modes, they are accessible at smaller scales via
+interferometers and pulsar timing arrays.",1906.07204v1
+2019-06-19,Edge localization of spin waves in antidot multilayers with perpendicular magnetic anisotropy,"We study the spin-wave dynamics in nanoscale antidot lattices based on Co/Pd
+multilayers with perpendicular magnetic anisotropy. Using time-resolved
+magneto-optical Kerr effect measurements we demonstrate that the variation of
+the antidot shape introduces significant change in the spin-wave spectra,
+especially in the lower frequency range. By employing micromagnetic simulations
+we show that additional peaks observed in the measured spectra are related to
+narrow shell regions around the antidots, where the magnetic anisotropy is
+reduced due to the Ga+ ion irradiation during the focused ion beam milling
+process of the antidot fabrication. The results point at new possibilities for
+exploitation of localized spin waves in out-of-plane magnetized thin films,
+which are easily tunable and suitable for magnonics applications.",1906.08109v2
+2019-06-20,Intrinsic origin of interfacial second-order magnetic anisotropy in ferromagnet/normal metal heterostructures,"Interfacial perpendicular magnetic anisotropy, which is characterized by the
+first-order (K1) and second-order (K2) anisotropies, is the core phenomenon for
+nonvolatile magnetic devices. A sizable K2 satisfying a specific condition
+stabilizes the easy-cone state, where equilibrium magnetization forms at an
+angle from the film normal. The easy-cone state offers intriguing possibilities
+for advanced spintronic devices and unique spin textures, such as spin
+superfluids and easy-cone domain walls. Experimental realization of the
+easy-cone state requires understanding the origin of K2, thereby enhancing K2.
+However, previously proposed origins of K2 cannot fully account for
+experimental results. Here we show experimentally that K2 scales almost
+linearly with the work-function difference between the Co and X layers in
+Pt/Co/X heterostructures (X = Pd, Cu, Pt, Mo, Ru, W, and Ta), suggesting the
+central role of the inversion asymmetry in K2. Our result provides a guideline
+for enhancing K2 and realizing magnetic applications based on the easy-cone
+state.",1906.08450v1
+2019-06-20,Effects of spin-orbit coupling on the neutron spin resonance in iron-based superconductors,"The so-called neutron spin resonance consists of a prominent enhancement of
+the magnetic response at a particular energy and momentum transfer upon
+entering the superconducting state of unconventional superconductors. In the
+case of iron-based superconductors, the neutron resonance has been extensively
+studied experimentally, and a peculiar spin-space anisotropy has been
+identified by polarized inelastic neutron scattering experiments. Here we
+perform a theoretical study of the energy- and spin-resolved magnetic
+susceptibility in the superconducting state with $ s_{+-} $-wave order
+parameter, relevant to iron-pnictide and iron-chalcogenide superconductors. Our
+model is based on a realistic bandstructure including spin-orbit coupling with
+electronic Hubbard-Hund interactions included at the RPA level. Spin-orbit
+coupling is taken into account both in the generation of spin-fluctuation
+mediated pairing, as well as the numerical computation of the spin
+susceptibility in the superconducting state. We find that spin-orbit coupling
+and superconductivity in conjunction can reproduce the salient experimentally
+observed features of the magnetic anisotropy of the neutron resonance. This
+includes the possibility of a double resonance, the tendency for a $c$-axis
+polarized resonance, and the existence of enhanced magnetic anisotropy upon
+entering the superconducting phase.",1906.08566v1
+2019-06-27,Extrinsic Spin-Orbit Coupling and Spin Relaxation in Phosphorene,"An effective Hamiltonian is derived to describe the conduction band of
+monolayer black phosphorus (phosphorene) in the presence of spin-orbit coupling
+and external electric field. Envelope function approximation along with
+symmetry arguments and Lowdin partitioning are utilized to derive extrinsic
+spin-orbit coupling. The resulting spin splitting appears in fourth order
+perturbation terms and is shown to be linear in both the magnitude of the
+external electric field and the strength of the atomic spin-orbit coupling,
+similar to the Bychkov-Rashba expression but with an in-plane anisotropy. The
+anisotropy depends on the coupling between conduction band and other bands both
+close and distant in energy. The spin relaxation of conduction electrons is
+then calculated within the Dyakonov-Perel mechanism where momentum scattering
+randomizes the polarization of a spin ensemble. We show how the anisotropic
+Fermi contour and the anisotropic extrinsic spin splitting contribute to the
+anisotropy of spin-relaxation time. Scattering centers in the substrate are
+considered to be charged impurities with screened Coulomb potential.",1906.11939v2
+2019-06-28,"Influence of anisotropy, tilt and pairing of Weyl nodes: The Weyl semimetals TaAs, TaP, NbAs and NbP","By means of $ab \ initio$ band structure methods and model Hamiltonians we
+investigate the electronic, spin and topological properties of four
+monopnictides crystallizing in body centered tetragonal structure. We show that
+the Weyl bands around a Weyl point W1 or W2 possess a strong anisotropy and
+tilt of the accompanying Dirac cones. These effects are larger for W2 nodes
+than for W1 ones. The node tilts and positions in energy space significantly
+influence the density of states of single-particle Weyl excitations. The node
+anisotropies destroy the conventional picture of (anti)parallel spin and wave
+vector of a Weyl fermion. This also holds for the Berry curvature around a
+node, while the monopole charges are independent as integrated quantities. The
+pairing of the nodes strongly modify the spin texture and the Berry curvature
+for wave vectors in between the two nodes. Spin components may change their
+orientation. Integrals over planes perpendicular to the connection line yield
+finite Zak phases and winding numbers for planes between the two nodes, thereby
+indicating the topological character.",1906.12231v2
+2019-06-30,Heavy ion anisotropies: a closer look at the angular power spectrum,"Anisotropies in the final state of heavy-ion collisions carry information on
+the creation, expansion and evolution of the quark-gluon plasma. Currently,
+there is an abundance of studies on azimuthal anisotropies in comparison to
+longitudinal ones. The purpose of this work is to quantify angular $(\theta,
+\phi)$ correlations to further the understanding of the full spatial 3-D
+picture of emitted hadrons. Therefore, public ALICE data from Run 1 (2010) of
+Pb-Pb collisions at $\sqrt{s_{NN}} = 2.76\mathrm{~TeV}$ is analyzed through the
+estimation of an angular power spectrum. Issues with $|\eta| < 0.9$ limitation
+are tackled, as well as event multiplicity and detector efficiency. Firstly,
+spectra are calculated for toy Monte Carlo samples. Secondly, heavy-ion data
+spectra are presented for the full momentum phase space $0.15 < p_T <
+100\mathrm{~GeV}$ and also separate intervals $p_T < 0.54\mathrm{~GeV}$ and
+$p_T > 0.54\mathrm{~GeV}$. The latter reveal how different geometries dominate
+at distinct scales and transverse momentum. Finally, the study submits
+particles generated through the AMPT model to the same power spectrum analysis.
+This comparison shows that in scales dominated by flow geometry, AMPT
+qualitatively describes the data spectra, while the opposite is true for
+smaller scales.",1907.00413v2
+2019-07-24,Improved limits on a stochastic gravitational-wave background and its anisotropies from Advanced LIGO O1 and O2 runs,"We integrate the entire, publicly available, Advanced LIGO (ALIGO) data set
+to obtain maximum-likelihood constraint maps of the Stochastic
+Gravitational-Wave Background (SGWB). From these we derive limits on the energy
+density of the stochastic background $\Omega_{\rm GW}$, and its anisotropy. We
+find 95% confident limits $\Omega_{\rm GW} < 5.2\times 10^{-8}$ at $50$ Hz for
+a spectral index $\alpha=2/3$ consistent with a stochastic background due to
+inspiral events and $\Omega_{\rm GW} < 3.2\times 10^{-7}$ for a scale
+(frequency) invariant spectrum. We also report upper limits on the angular
+power spectra $C_\ell$ for three broadband integrations of the data. Finally we
+present an estimate where we integrate the data into ten separate spectral bins
+as a first attempt to carry out a model-independent estimate the SGWB and its
+anisotropies.",1907.10329v1
+2019-07-25,Splitting of antiferromagnetic resonance modes in the quasi-two-dimensional collinear antiferromagnet Cu(en)(H$_2$O)$_2$SO$_4$,"Low-temperature magnetic resonance study of the quasi-two-dimensional
+antiferromagnet Cu(en)(H$_2$O)$_2$SO$_4$ (en = C$_2$H$_8$N$_2$) was performed
+down to 0.45~K. This compound orders antiferromagnetically at 0.9K. The
+analysis of the resonance data within the hydrodynamic approach allowed to
+identify anisotropy axes and to estimate the anisotropy parameters for the
+antiferromagnetic phase. Dipolar spin-spin coupling turns out to be the main
+contribution to the anisotropy of the antiferromagnetic phase. The splitting of
+the resonance modes and its non-monotonous dependency on the applied frequency
+was observed below 0.6K in all three field orientations. Several models were
+discussed to explain the origin of the nontrivial splitting and the existence
+of inequivalent magnetic subsystems in Cu(en)(H$_2$O)$_2$SO$_4$ was chosen as
+the most probable source.",1907.11140v2
+2019-08-02,Origin of magnetic anisotropy in the spin ladder compound (C$_5$H$_{12}$N)$_2$CuBr$_4$,"The $S=1/2$ spin ladder compound (C$_5$H$_{12}$N)$_2$CuBr$_4$ (BPCB) is
+studied by means of high-resolution inelastic neutron scattering. In agreement
+with previous studies we find a band of triplet excitations with a spin gap of
+$\sim0.8$~meV and a bandwidth of $\sim0.6$~meV. In addition, we observe a
+distinct splitting of the triplet band of $50(1)$~$\mu$eV or $40(2)$~$\mu$eV at
+the band minimum or maximum, respectively. By comparison to a strong coupling
+expansion calculation of the triplet dispersion for a spin ladder with
+anisotropic exchange, weakly anisotropic leg interactions are identified as the
+dominant source of magnetic anisotropy in BPCB. Based on these results, we
+discuss the nature of magnetic exchange anisotropy in BPCB and in related
+transition-metal insulators.",1908.00724v2
+2019-08-14,Propagation of Gravitational Waves in Anisotropic Universe,"In this paper, we have considered a toy model of an anisotropic universe and
+studied the propagation of gravitational waves in such a universe. The
+consideration of this toy model simplifies the analysis and helps us to
+illustrate the effects of anisotropy. Incorporating linear perturbations on
+this anisotropic background, we have considered the synchronous, transverse,
+traceless gauge conditions and evaluated the perturbations of the Ricci tensor.
+The energy-momentum tensor is that of a perfect fluid, for which the Einstein's
+field equations are determined in presence of perturbations. We arrive at the
+set of linearised Einstein's equations explicitly and find solutions for
+gravitational waves propagating along the direction of anisotropy. We also
+study the propagation along a direction perpendicular to the direction of
+anisotropy. Subsequently we have validated the assumption of the tracelessness
+of the linear perturbations. Finally we determine the amount of tidal
+acceleration caused by the propagation of gravitational waves in this
+background spacetime.",1908.06743v1
+2019-08-21,Designing Anisotropic Microstructures with Spectral Density Function,"Materials' microstructure strongly influences its performance and is thus a
+critical aspect in design of functional materials. Previous efforts on
+microstructure mediated design mostly assume isotropy, which is not ideal when
+material performance is dependent on an underlying transport phenomenon. In
+this article, we propose an anisotropic microstructure design strategy that
+leverages Spectral Density Function (SDF) for rapid reconstruction of high
+resolution, two phase, isotropic or anisotropic microstructures in 2D and 3D.
+We demonstrate that SDF microstructure representation provides an intuitive
+method for quantifying anisotropy through a dimensionless scalar variable
+termed anisotropy index. The computational efficiency and low dimensional
+microstructure representation enabled by our method is demonstrated through an
+active layer design case study for Bulk Heterojunction Organic Photovoltaic
+Cells (OPVCs). Results indicate that optimized design, exhibiting strong
+anisotropy, outperforms isotropic active layer designs. Further, we show that
+Cross-sectional Scanning Tunneling Microscopy and Spectroscopy (XSTM/S) is as
+an effective tool for characterization of anisotropic microstructures.",1908.07661v1
+2019-08-28,Impact of Strong Anisotropy on Phase Diagram of Superfluid $^3$He in Aerogels,"Recently, one analog of the Anderson's Theorem for the $s$-wave
+superconductor has attracted much interest in the context of the $p$-wave polar
+pairing state of superfluid $^3$He in a model aerogel in the limit of strong
+uniaxial anisotropy. We discuss to what extent the theorem is satisfied in the
+polar phase in real aerogels by examining the normal to polar transition
+temperature $T_c$ and the low temperature behavior of the superfluid energy gap
+under an anisotropy of a moderate strength and comparing the obtained results
+with experimental data. The situation in which the Anderson's theorem clearly
+breaks down is also discussed.",1908.10712v4
+2019-09-06,Effect of Tantalum spacer thickness and deposition conditions on the properties of MgO/CoFeB/Ta/CoFeB/MgO free layers,"To get stable perpendicularly magnetized tunnel junctions at small device
+dimensions, composite free layers that comprise two MgO/FeCoB interfaces as
+sources of interface anisotropy are generally used. Proper cristallisation and
+annealing robustness is typically ensured by the insertion of a spacer layer of
+the early transition metal series within the FeCoB layer. We study the
+influence of the spacer thickness and growth condition on the switching metrics
+of tunnel junctions thermally annealed at 400$^\circ$C for the case of 1-4
+\r{A} Ta spacers. Thick Ta spacer results in a large anisotropies indicative of
+a better defined top FeCoB/MgO interface, but this is achieved at the
+systematic expense of a stronger damping. For the best anisotropy-damping
+compromise, junctions of diameter 22 nm can still be stable and spin-torque
+switched. Coercivity and inhomogeneous linewidth broadening, likely arising
+from roughness at the FeCoB/Ta interface, can be reduced if a sacrificial Mg
+layer is inserted before the Ta spacer deposition.",1909.02741v1
+2019-09-07,"Long-range order induced by random fields in two-dimensional O(n) models, and the Imry-Ma state","The influence of defects of the ""random local field"" type with an anisotropic
+distribution of random fields on two-dimensional models with continuous
+symmetry of the vector order parameter is considered. In the case of weak
+anisotropy of random fields, with decreasing temperature there takes place a
+smooth transition from the paramagnetic phase with dynamic fluctuations of the
+order parameter to the Imry-Ma phase with static fluctuations caused by
+fluctuations of the random field of defects. In the case of strong anisotropy
+of random fields, defects lead to an effective decrease in the number of
+components of the order parameter and the appearance of a phase transition to
+an ordered state at finite temperature. It is shown that in the case of the
+defect-free two-dimensional X-Y model, the appearance of an arbitrarily weak
+anisotropy in the two-dimensional space of the order parameter completely
+eliminates the appearance of the Berezinsky-Kosterlitz-Thouless phase and gives
+rise to the phase with the long-range order.",1909.03264v1
+2019-09-27,Gravitational Wave Anisotropies from Primordial Black Holes,"An observable stochastic background of gravitational waves is generated
+whenever primordial black holes are created in the early universe thanks to a
+small-scale enhancement of the curvature perturbation. We calculate the
+anisotropies and non-Gaussianity of such stochastic gravitational waves
+background which receive two contributions, the first at formation time and the
+second due to propagation effects. The former contribution can be generated if
+the distribution of the curvature perturbation is characterized by a local and
+scale-invariant shape of non-Gaussianity. Under such an assumption, we conclude
+that a sizeable magnitude of anisotropy and non-Gaussianity in the
+gravitational waves would suggest that primordial black holes may not comply
+the totality of the dark matter.",1909.12619v2
+2019-09-30,Bianchi spacetimes as super-curvature modes around isotropic cosmologies,"A powerful result in theoretical cosmology states that a subset of
+anisotropic Bianchi models can be seen as the homogeneous limit of (standard)
+linear cosmological perturbations. Such models are precisely those leading to
+Friedmann spacetimes in the limit of zero anisotropy. Building on previous
+works, we give a comprehensive exposition of this result, and perform the
+detailed identification between anisotropic degrees of freedom and their
+corresponding scalar, vector, and tensor perturbations of standard perturbation
+theory. In particular, we find that anisotropic models very close to open
+(i.e., negatively curved) Friedmann spaces correspond to some type of
+super-curvature perturbations. As a consequence, provided anisotropy is mild,
+its effects on all types of cosmological observables can always be computed as
+simple extensions of the standard techniques used in relativistic perturbation
+theory around Friedmann models. This fact opens the possibility to consistently
+constrain, for all cosmological observables, the presence of large scale
+anisotropies on the top of the stochastic fluctuations.",1909.13688v1
+2019-10-05,Resistivity anisotropy of quantum Hall stripe phases,"Quantum Hall stripe phases near half-integer filling factors $\nu \ge 9/2$
+were predicted by Hartree-Fock (HF) theory and confirmed by discoveries of
+giant resistance anisotropies in high-mobility two-dimensional electron gases.
+A theory of such anisotropy was proposed by MacDonald and Fisher, although they
+used parameters whose dependencies on the filling factor, electron density, and
+mobility remained unspecified. Here, we fill this void by calculating the
+hard-to-easy resistivity ratio as a function of these three variables.
+Quantitative comparison with experiment yields very good agreement which we
+view as evidence for the ""plain vanilla"" smectic stripe HF phases.",1910.02260v3
+2019-10-07,Three-Dimensional Stability of Current Sheets Supported by Electron Pressure Anisotropy,"The stability of electron current sheets embedded within the reconnection
+exhaust is studied with a 3D fully kinetic particle-in-cell simulation. The
+electron current layers studied here form self-consistently in a reconnection
+regime with a moderate guide field, are supported by electron pressure
+anisotropy with the pressure component parallel to the magnetic field direction
+larger than the perpendicular components, and extend well beyond electron
+kinetic scales. In 3D, in addition to drift instabilities common to nearly all
+reconnection exhausts, the regime considered also exhibits an electromagnetic
+instability driven by the electron pressure anisotropy. While the fluctuations
+modulate the current density on small scales, they do not break apart the
+general structure of the extended electron current layers. The elongated
+current sheets should therefore persist long enough to be observed both in
+space observations and in laboratory experiments.",1910.02848v1
+2019-10-07,The Role of Pressure Anisotropy in Cosmic Ray Hydrodynamics,"Cosmic ray propagation in the Milky Way and other galaxies is largely
+diffusive, with mean free path determined primarily by pitch angle scattering
+from hydromagnetic waves with wavelength of order the cosmic ray gyroradius. In
+the theory of cosmic ray self confinement, the waves are generated by
+instabilities driven by the cosmic rays themselves. The dominant instability is
+due to bulk motion, or streaming, of the cosmic rays, parallel to the
+background magnetic field B, and transfers cosmic ray momentum and energy to
+the thermal gas as well as confining the cosmic rays. Classical arguments and
+recent numerical simulations show that self confinement due to the streaming
+instability breaks down unless the cosmic ray pressure and thermal gas density
+gradients parallel to B are aligned, a condition which is unlikely to always be
+satisfied We investigate an alternative mechanism for cosmic ray self
+confinement and heating of thermal gas based on pressure anisotropy
+instability. Although pressure anisotropy is demonstrably less effective than
+streaming instability as a self confinement and heating mechanism on global
+scales, it may be important on mesoscales, particularly near sites of cosmic
+ray injection.",1910.03052v1
+2019-10-10,Transition between dissipatively stabilized helical states,"We analyze a $XXZ$ spin-1/2 chain which is driven dissipatively at its
+boundaries. The dissipative driving is modelled by Lindblad jump operators
+which only act on both boundary spins. In the limit of large dissipation, we
+find that the boundary spins are pinned to a certain value and at special
+values of the interaction anisotropy, the steady states are formed by a rank-2
+mixture of helical states with opposite winding numbers. Contrarily to previous
+stabilization of topological states, these helical states are not protected by
+a gap in the spectrum of the Lindbladian. By changing the anisotropy, the
+transition between these steady states takes place via mixed states of higher
+rank. In particular, crossing the value of zero anisotropy a totally mixed
+state is found as the steady state. The transition between the different
+winding numbers via mixed states can be seen in the light of the transitions
+between different topological states in dissipatively driven systems. The
+results are obtained developing a perturbation theory in the inverse
+dissipative coupling strength and using the numerical exact diagonalization and
+matrix product state methods.",1910.04501v1
+2019-10-10,The synergy between CMB spectral distortions and anisotropies,"Spectral distortions and anisotropies of the CMB provide independent and
+complementary probes to study energy injection processes in the early universe.
+Here we discuss the synergy between these observables, and show the promising
+future of spectral distortion missions to constrain both exotic and non-exotic
+energy injections. We show that conventional probes such as Big Bang
+Nucleosynthesis and CMB anisotropies can benefit from and even be surpassed by
+future spectral distortion experiments. For this, we have implemented a unified
+framework within the Boltzmann code CLASS to consistently treat the thermal
+evolution of photons and baryons. Furthermore, we give an extensive and
+pedagogical introduction into the topic of spectral distortions and energy
+injections throughout the thermal history of the universe, highlighting some of
+their unique features and potential as a novel probe for cosmology and particle
+physics.",1910.04619v3
+2019-10-10,A unified view of anisotropies in the astrophysical gravitational wave background,"In the literature different approaches have been proposed to compute the
+anisotropies of the astrophysical gravitational wave background. The different
+expressions derived, although starting from our work Cusin, Pitrou, Uzan,
+Phys.Rev.D96, 103019 (2017) [1], seem to differ. This article compares the
+various theoretical expressions proposed so far and provides a separate
+derivation based on a Boltzmann approach. We show that all the theoretical
+formula in the literature are equivalent and boil down to the one of Ref. [1]
+when a proper matching of terms and integration by parts are performed. The
+difference between the various predictions presented for anisotropies in a
+cosmological context can only lie in the astrophysical modeling of sources, and
+neither in the theory nor in the cosmological description of the large scale
+structures. Finally we comment on the gauge invariance of expressions.",1910.04645v2
+2019-10-15,"Rotational transition, domain formation, dislocations and defects in vortex systems with combined six- and 12-fold anisotropic interactions","We introduce a new model for a pairwise repulsive interaction potential of
+vortices in a type-II superconductor, consisting of superimposed six- and
+12-fold anisotropies. Using numerical simulations we study how the vortex
+lattice configuration varies as the magnitudes of the two anisotropic
+interaction terms change. A triangular lattice appears for all values, and
+rotates through 30 degrees as the ratio of the six- and 12-fold anisotropy
+amplitudes is varied. The transition causes the VL to split into domains that
+have rotated clockwise or counter-clockwise, with domain boundaries that are
+""decorated"" by dislocations consisting of five- and seven-fold coordinated
+vortices. We also find intra-domain dislocations and defects, and characterize
+them in terms of their energy cost. We discuss how this model could be
+generalized to other particle-based systems with anisotropic interactions, such
+as colloids, and consider the limit of very large anisotropy where it is
+possible to create cluster crystal states.",1910.06885v2
+2019-10-01,Magnetocaloric effect in molecular spin clusters and their assemblies: model exact and Monte Carlo studies,"We study the magnetocaloric effect (MCE) in spin clusters of six spins with
+site spins $s=1$, $3/2$ and $2$ for different exchange anisotropies. We also
+study MCE in an assembly of spin clusters, on a chain, a 2-D square lattice and
+3-D cubic lattice with spin-dipolar interactions using a Monte Carlo method in
+spin-1 systems. We compute the magnetic Gr\""uneisen parameter $\Gamma_H$, and
+study its dependence on exchange anisotropy and spin-dipolar interaction. With
+increase of exchange anisotropy the maxima in $\Gamma_H$, shifts to higher
+magnetic fields and becomes a sharp singularity. The first maximum in
+$\Gamma_H$ shifts to lower fields as we increase spin-dipolar interaction. The
+behaviour of $\Gamma_H$ on applied magnetic field is also reflected in the
+magnetic entropy of the systems. The first maximum in $\Gamma_H$ also shifts to
+lower magnetic field strength as the magnitude of the site spin increases. We
+also show the dependence of $\Gamma_H$ on dimensionality of the lattice for a
+fixed lattice constant.",1910.07085v2
+2019-10-31,Possibility of a continuous phase transition in random-anisotropy magnets with ageneric random-axis distribution,"We reconsider the problem of the critical behavior of a three-dimensional
+$O(m)$ symmetric magnetic system in the presence of random anisotropy disorder
+with a generic trimodal random axis distribution. By introducing $n$ replicas
+to average over disorder it can be coarse-grained to a $\phi^{4}$-theory with
+$m \times n$ component order parameter and five coupling constants taken in the
+limit of $n \to 0$. Using a field theory approach we renormalize the model to
+two-loop order and calculate the $\beta$-functions within the $\varepsilon$
+expansion and directly in three dimensions. We analyze the corresponding
+renormalization group flows with the help of the Pad\'e-Borel resummation
+technique. We show that there is no stable fixed point accessible from physical
+initial conditions whose existence was argued in the previous studies. This may
+indicate an absence of a long-range ordered phase in the presence of random
+anisotropy disorder with a generic random axis distribution.",1910.14461v2
+2019-11-06,Surfing multiple conformation-property landscapes via machine learning: Designing magnetic anisotropy,"The advent of computational statistical disciplines, such as machine
+learning, is leading to a paradigm shift in the way we conceive the design of
+new compounds. Today computational science does not only provide a sound
+understanding of experiments, but also can directly design the best compound
+for specific applications. This approach, known as reverse engineering,
+requires the construction of models able to efficiently predict continuous
+structure-property maps. Here we show that reverse engineering can be used to
+tune the magnetic properties of a single-ion molecular magnet in an automated
+intelligent fashion. We design a machine learning model to predict both the
+energy and magnetic properties as function of the chemical structure. Then, a
+particle-swarm optimization algorithm is used to explore the conformational
+landscapes in the search for new molecular structures leading to an enhanced
+magnetic anisotropy. We find that a 5% change in one of the coordination angles
+leads to a 50% increase in the anisotropy. Our approach paves the way for a
+machine-learning-driven exploration of the chemical space of general classes of
+magnetic materials. Most importantly, it can be applied to any
+structure-property relation and offers an effective way to automatically
+generate new materials with target properties starting from the knowledge of
+previously synthesized ones.",1911.02263v1
+2019-11-08,Giant anisotropy of Gilbert damping in a Rashba honeycomb antiferromagnet,"Giant Gilbert damping anisotropy is identified as a signature of strong
+Rashba spin-orbit coupling in a two-dimensional antiferromagnet on a honeycomb
+lattice. The phenomenon originates in spin-orbit induced splitting of
+conduction electron subbands that strongly suppresses certain spin-flip
+processes. As a result, the spin-orbit interaction is shown to support an
+undamped non-equilibrium dynamical mode that corresponds to an ultrafast
+in-plane N\'eel vector precession and a constant perpendicular-to-the-plane
+magnetization. The phenomenon is illustrated on the basis of a two dimensional
+$s$-$d$ like model. Spin-orbit torques and conductivity are also computed
+microscopically for this model. Unlike Gilbert damping these quantities are
+shown to reveal only a weak anisotropy that is limited to the semiconductor
+regime corresponding to the Fermi energy staying in a close vicinity of
+antiferromagnetic gap.",1911.03408v1
+2019-11-13,Perpendicular Magnetic Anisotropy in Conducting NiCo2O4 Films from Spin-Lattice Coupling,"High perpendicular magnetic anisotropy (PMA), a property needed for nanoscale
+spintronic applications, is rare in oxide conductors. We report the observation
+of a PMA up to 0.23 MJ/m3 in modestly strained epitaxial NiCo2O4 (NCO) films
+which are room-temperature ferrimagnetic conductors. Spin-lattice coupling
+manifested as magnetoelastic effect was found as the origin of the PMA. The
+in-plane xx-yy states of Co on tetrahedral sites play crucial role in the
+magnetic anisotropy and spin-lattice coupling with an energy scale of 1
+meV/f.u. The elucidation of the microscopic origin paves a way for engineering
+oxide conductors for PMA using metal/oxygen hybridizations.",1911.05322v1
+2019-11-25,Spin-valve Josephson junctions with perpendicular magnetic anisotropy for cryogenic memory,"We demonstrate a Josephson junction with a weak link containing two
+ferromagnets, with perpendicular magnetic anisotropy and independent switching
+fields in which the critical current can be set by the mutual orientation of
+the two layers. Such pseudospin-valve Josephson junctions are a candidate
+cryogenic memory in an all superconducting computational scheme. Here, we use
+Pt/Co/Pt/CoB/Pt as the weak link of the junction with $d_\text{Co} = 0.6$ nm,
+$d_\text{CoB} = 0.3$ nm, and $d_\text{Pt} = 5$ nm and obtain a $60\%$ change in
+the critical current for the two magnetization configurations of the
+pseudospin-valve. Ferromagnets with perpendicular magnetic anisotropy have
+advantages over magnetization in-plane systems which have been exclusively
+considered to this point, as in principle the magnetization and magnetic
+switching of layers in the junction should not affect the in-plane magnetic
+flux.",1911.11051v2
+2019-11-26,Enhanced anisotropy and study of magnetization reversal in Co/C60 bilayer thin film,"The interface between organic semiconductor [OSC]/ferromagnetic [FM] material
+can exhibit ferromagnetism due to their orbital hybridization. Charge/spin
+transfer may occur from FM to OSC layer leading to the formation of
+`spinterface' i.e. the interface exhibiting a finite magnetic moment. In this
+work, the magnetic properties of Co/C$_{60}$ bilayer thin film have been
+studied to probe the interface between Co and C$_{60}$ layer. Polarized neutron
+reflectivity [PNR] measurement indicates that the thickness and moment of the
+spinterface are $\sim$ 2 $\pm$ 0.18 nm and 0.8 $\pm$ 0.2 $\mu_B$/cage,
+respectively. The comparison of the magnetization reversal between the
+Co/C$_{60}$ bilayer and the parent single layer Co thin film reveals that
+spinterface modifies the domain microstructure. Further, the anisotropy of the
+bilayer system shows a significant enhancement ($\sim$ two times) in comparison
+to its single layer counterpart which is probably due to an additional
+interfacial anisotropy arising from the orbital hybridization at the
+Co/C$_{60}$ interface.",1911.11873v1
+2019-12-06,Increased Curie temperature and enhanced perpendicular magneto anisotropy of Cr2Ge2Te6/NiO heterostructure,"Magnetism in two-dimensional van der Waals materials has received significant
+attention recently. The Curie temperature reported for those materials,
+however, has been so far remained relatively low. Here, we measure
+magneto-optical Kerr effects (MOKE) under perpendicular magnetic field for van
+der Waals ferromagnet Cr2Ge2Te6 as well as its heterostructure with
+antiferromagnetic insulator NiO. We observe a notable increase in both Curie
+temperature and magnetic perpendicular anisotropy in Cr2Ge2Te6/NiO
+heterostructures compared to those in Cr2Ge2Te6. Measurements on the same
+exfoliated Cr2Ge2Te6 flake (on a SiO2/Si substrate) before and after depositing
+NiO show that the hysteresis loop can change into a square shape with larger
+coercive field for Cr2Ge2Te6/NiO. The maximum Curie temperature (TC) observed
+for Cr2Ge2Te6/NiO reaches ~120 K, is nearly twice the maximum TC ~ 60 K
+reported for Cr2Ge2Te6 alone. Both enhanced perpendicular anisotropy and
+increased Curie temperature are observed for Cr2Ge2Te6 flakes with a variety of
+thicknesses ranging from ~5 nm to ~200 nm. The results indicate that magnetic
+properties of two-dimensional van der Waals magnets can be engineered and
+controlled by using the heterostructure interface with other materials.",1912.03147v1
+2019-12-11,Implications for cosmology from Ground-based Cosmic Microwave Background observations,"Cosmic Microwave Background (CMB) anisotropy encodes a lot of information
+about our Universe. In this paper we take the ground-based CMB observations
+(GCMB), including the South Pole Telescope (SPT), SPTpol and the Atacama
+Cosmology Telescope Polarimeter (ACTPol), as a new probe to the CMB anisotropy
+independent of two satellite observations, i.e. Wilkinson Microwave Anisotropy
+Probe (WMAP) and Planck. The combination of current GCMB data is consistent
+with WMAP and Planck. In the spatially flat $\Lambda$CDM model, the Hubble
+constant is $H_0=69.72\pm 1.63$ km/s/Mpc at $68\%$ confidence level (CL).
+Combining with baryon acoustic oscillation (BAO) and the Pantheon sample of
+Type Ia supernovae (SN), we find that $H_0=68.40\pm 0.58$ km/s/Mpc ($68\%$ CL)
+in the spatially flat $\Lambda$CDM cosmology which has a tension with local
+measurement given by Riess et al. in 2019 at $3.7\sigma$ level, and
+$\Omega_k=-0.0013\pm 0.0039$ and $N_{\rm{eff}}=2.90\pm 0.41$ ($68\%$ CL) in the
+extended cosmological models.",1912.05491v2
+2019-12-17,Gapped $Z_2$ spin liquid in the breathing kagome Heisenberg antiferromagnet,"We investigate the spin-1/2 Heisenberg antiferromagnet on the kagome lattice
+with breathing anisotropy (i.e. with weak and strong triangular units),
+constructing an improved simplex Resonating Valence Bond (RVB) ansatz by
+successive applications (up to three times) of local quantum gates which
+implement a filtering operation on the bare nearest-neighbor RVB state. The
+resulting Projected Entangled Pair State involves a small number of variational
+parameters (only one at each level of application) and preserves full lattice
+and spin-rotation symmetries. Despite its simple analytic form, the simplex RVB
+provides very good variational energies at strong and even intermediate
+breathing anisotropy. We show that it carries $Z_2$ topological order which
+does not fade away under the first few applications of the quantum gates,
+suggesting that the RVB topological spin liquid becomes a competing ground
+state candidate for the kagome antiferromagnet at large breathing anisotropy.",1912.08284v1
+2019-12-19,Origin of Magnetic Ordering in a Structurally-Perfect Quantum Kagome Antiferromagnet,"The ground state of the simple Heisenberg nearest-neighbor quantum kagome
+antiferromagnetic model is a magnetically disordered spin liquid, yet various
+perturbations may lead to fundamentally different states. Here we disclose the
+origin of magnetic ordering in the structurally-perfect kagome material
+YCu$_3$(OH)$_6$Cl$_3$, which is free of the widespread impurity problem. {\it
+Ab-initio} calculations and modeling of its magnetic susceptibility reveal
+that, similar to the archetypal case of herbertsmithite, the nearest-neighbor
+exchange is by far the dominant isotropic interaction. Dzyaloshinskii-Moriya
+(DM) magnetic anisotropy deduced from electron spin resonance and specific-heat
+measurements is, however, significantly larger than in herbertsmithite. By
+enhancing spin correlations within kagome planes, this anisotropy is essential
+for magnetic ordering. Our study isolates the effect of DM anisotropy from
+other perturbations and unambiguously confirms the theoretical phase diagram.",1912.09047v2
+2020-01-06,Enhanced voltage-controlled magnetic anisotropy via magneto-elasticity in FePt/MgO(001),"The interplay between magneto-electricity (ME) and magneto-elasticity (MEL)
+is studied in the context of voltage-controlled magnetic anisotropy (VCMA).
+Strain plays more than a role of changing lattice constant but that of the
+internal electric field in the heterostructure. As a prototype, FePt/MgO(001)
+is visited, where the behavior of two interfaces are drastically different: one
+exhibits switching the other does not. Whether an external electric field
+($E_{ext}$) is present or not, we found VCMA coefficient larger than 1
+pJ/V$\cdot$m, as a consequence of the rearrangement of $d$ orbitals with
+$m=\pm1$ and $\pm2$ in response to an external electric field. In addition,
+magneto-crystalline anisotropy (MA) is analyzed with strain taken into account,
+where non-linear feature is presented only accountable by invoking second-order
+MEL.",2001.01464v1
+2020-01-21,High order magnon bound states in the quasi-one-dimensional antiferromagnet $α$-NaMnO$_2$,"Here we report on the formation of two and three magnon bound states in the
+quasi-one-dimensional antiferromagnet $\alpha$-NaMnO$_2$, where the single-ion,
+uniaxial anisotropy inherent to the Mn$^{3+}$ ions in this material provides a
+binding mechanism capable of stabilizing higher order magnon bound states.
+While such states have long remained elusive in studies of antiferromagnetic
+chains, neutron scattering data presented here demonstrate that higher order
+$n>2$ composite magnons exist, and, specifically, that a weak three-magnon
+bound state is detected below the antiferromagnetic ordering transition of
+NaMnO$_2$. We corroborate our findings with exact numerical simulations of a
+one-dimensional Heisenberg chain with easy-axis anisotropy using matrix-product
+state techniques, finding a good quantitative agreement with the experiment.
+These results establish $\alpha$-NaMnO$_2$ as a unique platform for exploring
+the dynamics of composite magnon states inherent to a classical
+antiferromagnetic spin chain with Ising-like single ion anisotropy.",2001.07300v1
+2020-01-28,Quantifying the Redshift Space Distortion of the Bispectrum I: Primordial Non-Gaussianity,"The anisotropy of the redshift space bispectrum contains a wealth of
+cosmological information. This anisotropy depends on the orientation of three
+vectors ${\bf k_1,k_2,k_3}$ with respect to the line of sight. Here we have
+decomposed the redshift space bispectrum in spherical harmonics which
+completely quantify this anisotropy. To illustrate this we consider linear
+redshift space distortion of the bispectrum arising from primordial
+non-Gaussianity. In the plane parallel approximation only the first four even
+$\ell$ multipoles have non-zero values, and we present explicit analytical
+expressions for all the non-zero multipoles {\it i.e.} upto $\ell=6,m=4$. The
+ratio of the different multipole moments to the real space bispectrum depends
+only on $\beta_1$ the linear redshift distortion parameter and the shape of the
+triangle. Considering triangles of all possible shapes, we have studied how
+this ratio depends on the shape of the triangle for $\beta_1=1$. We have also
+studied the $\beta_1$ dependence for some of the extreme triangle shapes. If
+measured in future, these multipole moments hold the potential of constraining
+$\beta_1$. The results presented here are also important if one wishes to
+constrain $f_{\text{NL}}$ using redshift surveys.",2001.10243v1
+2020-01-29,Perpendicularly Magnetized Ni / Pt (001) Epitaxial Superlattice,"A perpendicularly magnetized ferromagnetic layer is an important building
+block for recent/future highdensity spintronic memory applications. This paper
+reports on the fabrication of perpendicularly magnetized Ni / Pt superlattices
+and the characterization of their structures and magnetic properties. The
+optimization of film growth conditions allowed us to grow epitaxial Ni / Pt
+(001) superlattices on SrTiO$_{3}$ (001) single crystal substrates. We
+investigated their structural parameters and magnetic properties as a function
+of the Ni layer thickness, and obtained a high uniaxial magnetic anisotropy
+energy of 1.9 x 10$^{6}$ erg/cm$^{3}$ for a [Ni (4.0 nm) / Pt (1.0 nm)]
+superlattice. In order to elucidate the detailed mechanism on perpendicular
+magnetic anisotropy for the Ni / Pt (001) superlattices, the experimental
+results were compared with the first-principles calculations. It has been found
+that the strain effect is a prime source of the emergence of perpendicular
+magnetic anisotropy.",2001.11127v1
+2020-01-30,Quantum approach to a Bianchi I singularity,"The approach of a quantum state to a cosmological singularity is studied
+through the evolution of its moments in a simple version of a Bianchi I model.
+In spite of the simplicity, the model exhibits several instructive and
+unexpected features of the moments. They are investigated here both
+analytically and numerically in an approximation in which anisotropy is assumed
+to vary slowly, while numerical methods are also used to analyze the case of a
+rapidly evolving anisotropy. Physical conclusions are drawn mainly regarding
+two questions. First, quantum uncertainty of anisotropies does not necessarily
+eliminate the existence of isotropic solutions, with potential implications for
+the interpretation of minisuperspace truncations as well as structure-formation
+scenarios in the early universe. Secondly, back-reaction of moments on basic
+expectation values is found to delay the approach to the classical singularity.",2001.11488v2
+2020-02-04,Deterministic control of an antiferromagnetic spin arrangement using ultrafast optical excitation,"A central prospect of antiferromagnetic spintronics is to exploit magnetic
+properties that are unavailable with ferromagnets. However, this poses the
+challenge of accessing such properties for readout and control. To this end,
+light-induced manipulation of the transient ground state, e.g. by changing the
+magnetic anisotropy potential, opens promising pathways towards ultrafast
+deterministic control of antiferromagnetism. Here, we use this approach to
+trigger a $\it{coherent}$ rotation of the entire long-range antiferromagnetic
+spin arrangement about a crystalline axis in $GdRh_2Si_2$ and demonstrate
+$\it{deterministic}$ control of this rotation upon ultrafast optical
+excitation. Our observations can be explained by a displacive excitation of the
+Gd spins$'$ local anisotropy potential by the optical excitation, allowing for
+a full description of this transient magnetic anisotropy potential.",2002.01398v1
+2020-02-17,Enhancement of magnetization plateaus in low dimensional spin systems,"We study the low-energy properties and, in particular, the magnetization
+process of a spin-1/2 Heisenberg $J_1-J_2$ sawtooth and frustrated chain (also
+known as zig-zag ladder) with a spatially anisotropic $g$-factor. We treat the
+problem both analytically and numerically while keeping the $J_2/J_1$ ratio
+generic. Numerically, we use complete and Lanczos diagonalization as well as
+the infinite time-evolving block decimation (iTEBD) method. Analytically we
+employ (non-)Abelian bosonization. Additionally for the sawtooth chain, we
+provide an analytical description in terms of flat bands and localized magnons.
+By considering a specific pattern for the $g$-factor anisotropy for both
+models, we show that a small anisotropy significantly enhances a magnetization
+plateau at half saturation. For the magnetization of the frustrated chain, we
+show the destruction of the $1/3$ of the full saturation plateau in favor of
+the creation of a plateau at half-saturation. For large anisotropies, the
+existence of an additional plateau at zero magnetization is possible. Here and
+at higher magnetic fields, the system is locked in the half-saturation plateau,
+never reaching full saturation.",2002.07190v1
+2020-02-19,Modeling the atomic structure in the vicinity of the spherical voids and calculation of void growth rate anisotropy in bcc iron and tungsten,"We study the influence of the atomic structure in the vicinity of voids on
+their growth rate anisotropy. In the first part, we model the atomic structure
+in the vicinity of nanovoids in Fe and W using the advanced Molecular Statics
+method. In the second part, we use the earlier obtained equations that taking
+the influence of elastic fields into account to calculate the shifting rate of
+the void surface elements, and to evaluate the components of the strain tensor
+we use the atomic structure modeling results from the first part. The
+calculations are performed for voids of several sizes at certain
+oversaturation's in a wide temperature range. The simulation results for the
+mentioned metals with a bcc structure show that displacements of atoms located
+along the crystallographic directions of the 100, 110, 111 types in the
+vicinity of the voids are significantly different, and this anisotropy of atom
+displacements leads to a reduction of spherical symmetry for the shifting rate
+of the surface elements. As the result, the initially spherical void shape
+becomes faceted.",2002.07943v1
+2020-02-25,Three-dimensional phonon population anisotropy in silicon nanomembranes,"Nanoscale single-crystals possess modified phonon dispersions due to the
+truncation of the crystal. The introduction of surfaces alters the population
+of phonons relative to the bulk and introduces anisotropy arising from the
+breaking of translational symmetry. Such modifications exist throughout the
+Brillouin zone, even in structures with dimensions of several nanometers,
+posing a challenge to the characterization of vibrational properties and
+leading to uncertainty in predicting the thermal, optical, and electronic
+properties of nanomaterials. Synchrotron x-ray thermal diffuse scattering
+studies find that freestanding Si nanomembranes with thicknesses as large as 21
+nm exhibit a higher scattering intensity per unit thickness than bulk silicon.
+In addition, the anisotropy arising from the finite thickness of these
+membranes produces particularly intense scattering along reciprocal-space
+directions normal to the membrane surface compared to corresponding in-plane
+directions. These results reveal the dimensions at which calculations of
+materials properties and device characteristics based on bulk phonon
+dispersions require consideration of the nanoscale size of the crystal.",2002.11196v1
+2020-03-01,A Study of Geometry in Anisotropic Quantum Hall States by Principal Component Analysis,"In the presence of mass anisotropy, anisotropic interaction, or in-plane
+magnetic field, quantum Hall droplets can exhibit shape deformation and
+internal geometrical degree of freedom. We characterize the geometry of quantum
+Hall states by principal component analysis, which is a statistical technique
+that emphasizes variation in a dataset. We first test the method in an integer
+quantum Hall droplet with dipole-dipole interaction in disk geometry. In the
+subsequent application to fractional quantum Hall systems with anisotropic
+Coulomb interaction in torus geometry, we demonstrate that the principal
+component analysis can quantify the metric degree of freedom and predict the
+collapse of a $\nu= 1/3$ state. We also calculate the metric response to
+interaction anisotropy at filling fractions $\nu= 1/5$ and $2/5$ and show that
+the response is roughly the same within the same Jain sequence, but can differ
+at large anisotropy for different sequences.",2003.00456v1
+2020-03-09,Measuring mechanical anisotropy of the cornea with Brillouin microscopy,"Load-bearing tissues are typically fortified by networks of protein fibers,
+often with preferential orientations. This fiber structure imparts the tissues
+with direction-dependent mechanical properties optimized to support specific
+external loads. To accurately model and predict tissues' mechanical response,
+it is essential to characterize the anisotropy on a microstructural scale.
+Previously, it has been difficult to measure the mechanical properties of
+intact tissues noninvasively. Here, we use Brillouin optical microscopy to
+visualize and quantify the anisotropic mechanical properties of corneal tissues
+at different length scales. We derive the stiffness tensor for a lamellar
+network of collagen fibrils and use angle-resolved Brillouin measurements to
+determine the longitudinal stiffness coefficients (longitudinal moduli)
+describing the ex vivo porcine cornea as a transverse isotropic material.
+Lastly, we observe significant mechanical anisotropy of the human cornea in
+vivo, highlighting the potential for clinical applications of off-axis
+Brillouin microscopy.",2003.04344v2
+2020-03-17,Domain wall dynamics in stepped magnetic nanowire with perpendicular magnetic anisotropy,"Micromagnetic simulation is carried out to investigate the current-driven
+domain wall (DW) in a nanowire with perpendicular magnetic anisotropy (PMA). A
+stepped nanowire is proposed to pin DW and achieve high information storage
+capacity based on multi-bit per cell scheme. The DW speed is found to increase
+for thicker and narrower nanowires. For depinning DW from the stepped region,
+the current density Jdep is investigated with emphasis on device geometry and
+materials intrinsic properties. The Jdep could be analytically determined as a
+function of the nanocontriction dimension and the thickness of the nanowire.
+Furthermore, Jdep is found to exponential dependent on the anisotropy energy
+and saturation magnetization, offering thus more flexibility in adjusting the
+writing current for memory applications.",2003.07721v1
+2020-03-27,Anisotropy-induced Extrinsic Chirality and Chiral Discrimination of Surface Plasmon Polaritons,"We present the characteristics of a simple waveguiding structure constructed
+by anisotropic birefringent crystal-metal-chiral medium,
+anisotropic-metal-chiral in short, and reveal the chiral-dependent dispersion
+and propagation properties of the surface plasmon polaritons (SPPs). We
+demonstrate its remarkable discrimination ability to the magnitude and sign of
+both the real and imaginary part of the chirality parameter. The anisotropy
+plays a key role in such performance and shows tuneable ability in enantiomeric
+discrimination even when the chirality parameter is complex-valued. Most
+importantly, the physical origin of chiral discrimination stems from the
+extrinsic chirality of the system, which arises from the mutual orientation of
+the SPPs and the optical axis. Moreover, we also clarify the fundamental
+physics behind the chiral discriminating behaviour by associating the intrinsic
+quantum spin Hall effect (QSHE) of the SPPs with the electromagnetic field
+analysis. This structure does not rely on complicated fabrication but provides
+the opportunity of on-chip surface-sensitive biosensing. We anticipate that our
+work will stimulate intensive research to investigate the anisotropy-induced
+chiral sensing techniques in plasmonic platforms.",2003.12453v1
+2020-04-01,Voltage- and temperature-dependent rare-earth dopant contribution to the interfacial magnetic anisotropy,"The control of magnetic materials and devices by voltages without electric
+currents holds the promise of power-saving nano-scale devices. Here we study
+the temperature-dependent voltage control of the magnetic anisotropy caused by
+rare-earth (RE) local moments at an interface between a magnetic metal and a
+non-magnetic insulator, such as Co|(RE)|MgO. Based on a Stevens operator
+representation of crystal and applied field effects, we find large dominantly
+quadrupolar intrinsic and field-induced interface anisotropies at room
+temperature. We suggest improved functionalities of transition metal tunnel
+junctions by dusting their interfaces with rare earths.",2004.00320v2
+2020-04-01,"Spin-transfer torque-driven motion, deformation, and instabilities of magnetic skyrmions at high currents","In chiral magnets, localized topological magnetic whirls, magnetic skyrmions,
+can be moved by spin polarized electric currents. Upon increasing the current
+strength, with prospects for high-speed skyrmion motion for spintronics
+applications in mind, isolated skyrmions deform away from their typical
+circular shape. We analyze the influence of spin-transfer torques on the shape
+of a single skyrmion, including its stability upon adiabatically increasing the
+strength of the applied electric current. For rather compact skyrmions at
+uniaxial anisotropies well above the critical anisotropy for domain wall
+formation, we find for high current densities that the skyrmion assumes a
+non-circular shape with a tail, reminiscent of a shooting star. For larger and
+hence softer skyrmions close to the critical anisotropy, in turn, we observe a
+critical current density above which skyrmions become unstable. We show that
+above a second critical current density the shooting star solution can be
+recovered also for these skyrmions.",2004.00450v2
+2020-04-09,Hysteresis-free magnetization reversal of exchange-coupled bilayers with finite magnetic anisotropy,"Exchange-coupled structures consisting of ferromagnetic and ferrimagnetic
+layers become technologically more and more important. We show experimentally
+the occurrence of completely reversible, hysteresis-free minor loops of [Co(0.2
+nm)/Ni(0.4 nm)/Pt(0.6 nm)]$_N$ multilayers exchange-coupled to a 20 nm thick
+ferrimagnetic Tb$_{28}$Co$_{14}$Fe$_{58}$ layer, acting as hard magnetic
+pinning layer. Furthermore, we present detailed theoretical investigations by
+means of micromagnetic simulations and most important a purely analytical
+derivation for the condition of the occurrence of full reversibility in
+magnetization reversal. Hysteresis-free loops always occur if a domain wall is
+formed during the reversal of the ferromagnetic layer and generates an
+intrinsic hard-axis bias field that overcomes the magnetic anisotropy field of
+the ferromagnetic layer. The derived condition further reveals that the
+magnetic anisotropy and the bulk exchange of both layers, as well as the
+exchange coupling strength and the thickness of the ferromagnetic layer play an
+important role for its reversibility.",2004.04419v1
+2020-04-11,Chirality of the gravitational-wave background and pulsar-timing arrays,"We describe the signatures of a circularly polarized gravitational-wave
+background on the timing residuals obtained with pulsar-timing arrays. Most
+generally, the circular polarization will depend on the gravitational-wave
+direction, and we describe this angular dependence in terms of spherical
+harmonics. While the amplitude of the monopole (the overall chirality of the
+gravitational-wave background) cannot be detected, measures of the anisotropy
+are theoretically conceivable. We provide expressions for the minimum-variance
+estimators for the circular-polarization anisotropy. We evaluate the smallest
+detectable signal as a function of the signal-to-noise ratio with which the
+isotropic GW signal is detected and the number of pulsars (assumed to be
+roughly uniformly spread throughout the sky) in the survey. We find that the
+overall dipole of the circular polarization and a few higher overall
+multipoles, are detectable in a survey with $\gtrsim100$ pulsars if their
+amplitude is close to maximal and once the isotropic signal is established with
+a signal-to-noise ratio $\gtrsim400$. Even if the anisotropy can be
+established, though, there will be limited information on its direction.
+Similar arguments apply to astrometric searches for gravitational waves.",2004.05480v1
+2020-04-14,Multimessenger Cosmology: correlating CMB and SGWB measurements,"Characterizing the physical properties of the stochastic gravitational waves
+background (SGWB) is a key step towards identifying the nature of its possible
+origin. We focus our analysis on SGWB anisotropies. The existence of a
+non-trivial primordial scalar-tensor-tensor (STT) correlation in the squeezed
+configuration may be inferred from the effect that a long wavelength scalar
+mode has on the gravitational wave power spectrum: an anisotropic contribution.
+Crucially, such contribution is correlated with temperature anisotropies in the
+cosmic microwave background (CMB). We show that, for inflationary models that
+generate suitably large STT non-Gaussianities, cross-correlating the CMB with
+the stochastic background of gravitational waves is a very effective probe of
+early universe physics. The resulting signal can be a smoking-gun for
+primordial SGWB anisotropies.",2004.06619v2
+2020-05-12,Anisotropic electrostatic screening of charged colloids in nematic solvents,"The physical behaviour of anisotropic charged colloids is determined by their
+material dielectric anisotropy, affecting colloidal self-assembly, biological
+function and even out-of-equilibrium behaviour. However, little is known about
+anisotropic electrostatic screening, which underlies all electrostatic
+effective interactions in such soft or biological materials. In this work, we
+demonstrate anisotropic electrostatic screening for charged colloidal particles
+in a nematic electrolyte. We show that material anisotropy behaves markedly
+different from particle anisotropy: The electrostatic potential and pair
+interactions decay with an anisotropic Debye screening length, contrasting the
+constant screening length for isotropic electrolytes. Charged dumpling-shaped
+near-spherical colloidal particles in a nematic medium are used as an
+experimental model system to explore the effects of anisotropic screening,
+demonstrating competing anisotropic elastic and electrostatic effective pair
+interactions for colloidal surface charges tunable from neutral to high,
+yielding particle-separated metastable states. Generally, our work contributes
+to the understanding of electrostatic screening in nematic anisotropic media.",2005.05682v2
+2020-05-13,Split Ga vacancies and the unusually strong anisotropy of positron annihilation spectra in $\boldsymbolβ$-Ga$_2$O$_3$,"We report a systematic first principles study on positron annihilation
+parameters in the $\beta$-Ga$_2$O$_3$ lattice and Ga mono-vacancy defects
+complemented with orientation-dependent experiments of the Doppler broadening
+of the positron-electron annihilation. We find that both the
+$\beta$-Ga$_2$O$_3$ lattice and the considered defects exhibit unusually strong
+anisotropy in their Doppler broadening signals. This anisotropy is associated
+with low symmetry of the $\beta$-Ga$_2$O$_3$ crystal structure that leads to
+unusual kind of one-dimensional confinement of positrons even in the
+delocalized state in the lattice. In particular, the split Ga vacancies
+recently observed by scanning transmission electron microscopy produce
+unusually anisotropic positron annihilation signals. We show that in
+experiments, the positron annihilation signals in $\beta$-Ga$_2$O$_3$ samples
+seem to be often dominated by split Ga vacancies.",2005.06283v2
+2020-05-13,"Direct Imaging, Three-dimensional Interaction Spectroscopy, and Friction Anisotropy of Atomic-scale Ripples on MoS$_{2}$","Theory predicts that two-dimensional (2D) materials may only exist in the
+presence of out-ofplane deformations on atomic length scales, frequently
+referred to as ripples. While such ripples can be detected via electron
+microscopy, their direct observation via surface-based techniques and
+characterization in terms of interaction forces and energies remain limited,
+preventing an unambiguous study of their effect on mechanical characteristics,
+including but not limited to friction anisotropy. Here, we employ
+high-resolution atomic force microscopy to demonstrate the presence of
+atomic-scale ripples on supported samples of few-layer molybdenum disulfide
+(MoS$_{2}$). Three-dimensional force / energy spectroscopy is utilized to study
+the effect of ripples on the interaction landscape. Friction force microscopy
+reveals multiple symmetries for friction anisotropy, explained by studying
+rippled sample areas as a function of scan size. Our experiments contribute to
+the continuing development of a rigorous understanding of the nanoscale
+mechanics of 2D materials.",2005.06442v1
+2020-05-16,Studies on binary mixtures of nematic liquid crystals made of strongly polar molecules with identical cores and antagonistic orientation of permanent dipoles,"We report experimental studies on optical (birefringence, $\Delta n$),
+dielectric $(\Delta \varepsilon)$ and bend-splay elastic anisotropies ($\Delta
+K=K_{33}-K_{11})$ of a few mixtures of two nematic liquid crystals, namely
+CCH-7 and CCN-47, made of highly polar molecules with identical cores and
+antagonistic orientation of permanent dipoles. In particular, the polar group
+(-CN) attached to the bicyclohexane core of CCH-7 is oriented along the
+longitudinal direction whereas, in CCN-47, it is oriented along the transverse
+direction. We show that apart from the significant contribution to the optical
+and dielectric anisotropies, the antagonistic orientation of strongly polar
+groups plays a crucial role in determining the bend-splay elastic anisotropy.
+The elastic properties are explained based on a model proposed by Priest,
+considering the effect of intermolecular association and the resulting
+length-to-width ratio of the molecules.",2005.07887v1
+2020-05-21,Theories with limited extrinsic curvature and a nonsingular anisotropic universe,"We propose a class of theories that can limit scalars constructed from the
+extrinsic curvature. Applied to cosmology, this framework allows us to control
+not only the Hubble parameter but also anisotropies without the problem of
+Ostrogradsky ghost, which is in sharp contrast to the case of limiting
+spacetime curvature scalars. Our theory can be viewed as a generalization of
+mimetic and cuscuton theories (thus clarifying their relation), which are known
+to possess a structure that limits only the Hubble parameter on homogeneous and
+isotropic backgrounds. As an application of our framework, we construct a model
+where both anisotropies and the Hubble parameter are kept finite at any stage
+in the evolution of the universe in the diagonal Bianchi type I setup. The
+universe starts from a constant-anisotropy phase and recovers Einstein gravity
+at low energies. We also show that the cosmological solution is stable against
+a wide class of perturbation wavenumbers, though instabilities may remain for
+arbitrary initial conditions.",2005.10844v2
+2020-06-02,Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics,"Cerium-based intermetallics are currently attracting much interest as a
+possible alternative to existing high-performance magnets containing scarce
+heavy rare-earth elements. However, the intrinsic magnetic properties of Ce in
+these systems are poorly understood due to the difficulty of a quantitative
+description of the Kondo effect, a many-body phenomenon where conduction
+electrons screen out the Ce-4f moment. Here, we show that the Ce-4f shell in
+Ce-Fe intermetallics is partially Kondo screened. The Kondo scale is
+dramatically enhanced by nitrogen interstitials completely suppressing the
+Ce-4f contribution to the magnetic anisotropy, in striking contrast to the
+effect of nitrogenation in isostructural intermetallics containing other
+rare-earth elements. We determine the full temperature dependence of the Ce-4f
+single-ion anisotropy and show that even unscreened Ce-4f moments contribute
+little to the room-temperature intrinsic magnetic hardness. Our study thus
+establishes fundamental constraints on the potential of cerium-based permanent
+magnet intermetallics.",2006.01792v2
+2020-06-08,Time-dependent spintronic anisotropy in magnetic molecules,"We theoretically study the quench dynamics of induced anisotropy of a
+large-spin magnetic molecule coupled to spin-polarized ferromagnetic leads. The
+real-time evolution is calculated by means of the time-dependent density-matrix
+numerical renormalization group method implemented within the matrix product
+states framework, which takes into account all correlations in very accurate
+manner. We determine the system's response to a quench in the spin-dependent
+coupling to ferromagnetic leads. In particular, we focus on the transient
+dynamics associated with crossing from the weak to the strong coupling regime,
+where the Kondo correlations become important. The dynamics is examined by
+calculating the time-dependent expectation values of the spin-quadrupole moment
+and the associated spin operators. We identify the relevant time scales
+describing the quench dynamics and determine the influence of the molecule's
+effective exchange coupling and leads spin-polarization on the dynamical
+behavior of the system. Furthermore, the generalization of our predictions for
+large values of molecule's spin is considered. Finally, we analyze the effect
+of finite temperature and show that it gives rise to a reduction of magnetic
+anisotropy by strong suppression of the time-dependent spin-quadrupole moment
+due to thermal fluctuations.",2006.04431v1
+2020-06-15,Control of Spin Relaxation Anisotropy by Spin-Orbit-Coupled Diffusive Spin Motion,"Spatiotemporal spin dynamics under spin-orbit interaction is investigated in
+a (001) GaAs two-dimensional electron gas using magneto-optical Kerr rotation
+microscopy. Spin polarized electrons are diffused away from the excited
+position, resulting in spin precession because of the diffusion-induced
+spin-orbit field. Near the cancellation between spin-orbit field and external
+magnetic field, the induced spin precession frequency depends nonlinearly on
+the diffusion velocity, which is unexpected from the conventional linear
+relation between the spin-orbit field and the electron velocity.This behavior
+originates from an enhancement of the spin relaxation anisotropy by the
+electron velocity perpendicular to the diffused direction. We demonstrate that
+the spin relaxation anisotropy, which has been regarded as a material constant,
+can be controlled via diffusive electron motion.",2006.08253v1
+2020-06-15,Influence of $XY$ anisotropy on a magnetoelectric effect in spin-1/2 $XY$ chain in a transverse magnetic field,"A magnetoelectric effect according to Katsura-Nagaosa-Balatsky mechanism in
+spin-1/2 $XY$ chain in transverse magnetic field is considered. A spatial
+orientation of the electric field is chosen to provide an exact solution of the
+model in terms of free spinless fermions. The simplest model of quantum spin
+chain demonstrating a magnetoelectric effect, a zero temperature case of the
+spin-1/2 $XX$ chain in a transverse magnetic field with
+Katsura-Nagaosa-Balatsky mechanism, is considered. The model has the simplest
+possible form of the magnetization, polarization and susceptibility functions,
+depending on electric and magnetic fields in a most simple form. For the case
+of arbitrary $XY$ anisotropy, a non-monotonous dependence of magnetization on
+the $XY$ anisotropy parameter is figured out. This non-uniform behaviour is
+governed by the critical point which is connected with the possibility to drive
+the system gapless or gapped by the electric field. Singularities of the
+magnetoelectric susceptibility at the critical value of system parameters are
+shown.",2006.08525v3
+2020-07-06,Quantum phase transitions in a spin-1 antiferromagnetic chain with long-range interactions and modulated single-ion anisotropy,"We study the phase diagram of spin-1 antiferromagnetic chain with isotropic
+antiferromagnetic interactions decaying with a power-law $\propto r^{-\alpha}$
+($\alpha\ge 1$) accompanied by modulated single-ion anisotropy. Employing the
+techniques of the density-matrix renormalization group, effects of long-range
+interactions and single-ion anisotropy on a variety of correlations are
+investigated. In order to check the consistency, the fidelity susceptibilities
+are evaluated across quantum phase transitions. The quantum critical points are
+faithfully detected and orders of phase transitions are determined. The
+correlation-length critical exponent is extracted from scaling functions of the
+fidelity susceptibility. The presence of long-range interactions leads to
+quantitative change of the phase boundaries and reduces the order of phase
+transition under certain conditions. A direct first-order transition between
+the periodic N\'eel phase and the large-$D$ phase occurs for slowly decaying
+antiferromagnetic interactions.",2007.02878v1
+2020-07-07,Investigation of in-plane anisotropy of c-axis magnetoresistance for BiCh2-based layered superconductor NdO0.7F0.3BiS2,"We have investigated the in-plane anisotropy of the c-axis magnetoresistance
+(MR) in both superconducting and normal states of single crystals of
+NdO0.7F0.3BiS2 under in-plane magnetic fields. In the superconducting states of
+NdO0.7F0.3BiS2, four-fold-symmetric in-plane anisotropy of the c-axis MR was
+observed below the superconducting transition temperature. Since the crystal
+structure of NdO0.7F0.3BiS2 is tetragonal, the rotational symmetry in the
+superconducting state is preserved in the present compound. This result is
+clearly different from the previous report observed in LaO0.5F0.5BiSSe single
+crystals, where the in-plane MR in the superconducting state shows two-fold
+symmetry. On the other hand, in the normal states of NdO0.7F0.3BiS2, two-fold
+symmetric MR with a small amplitude was observed. The possible origin of the
+two-fold-symmetric behavior was discussed with the presence of local structural
+disorder in the conducting plane of BiCh2-based compounds.",2007.03235v1
+2020-07-14,Giant magnetic anisotropy energy and long coherence time of uranium substitution on defected Al2O3(0001),"Nanomagnets with giant magnetic anisotropy energy and long coherence time are
+desired for various technological innovations such as quantum information
+procession and storage. Based on the first-principles calculations and model
+analyses, we demonstrate that a single uranium atom substituting Al on the
+Al2O3(0001) surface may have high structural stability and large magnetic
+anisotropy energy up to 48 meV per uranium atom. As the magnetization resides
+in the localized f-shell and is not much involved in chemical bonding with
+neighbors, long coherence time up to ~1.6 mS can be achieved for the quantum
+spin states. These results suggest a new strategy for the search of ultrasmall
+magnetic units for diverse applications in the quantum information era.",2007.07345v1
+2020-07-24,Reversible vs. irreversible voltage manipulation of interfacial magnetic anisotropy in Pt/Co/oxide multilayers,"The perpendicular magnetic anisotropy at the Co/oxide interface in Pt/Co/MOx
+(MOx = MgOx, AlOx, TbOx) was modified by an electric field using a 10 nm-thick
+ZrO2 as a solid electrolyte. The large voltage-driven modification of
+interfacial magnetic anisotropy and the non-volatility of the effect is
+explained in terms of the migration of oxygen ions towards/away from the Co/MOx
+interface. While the effect is reversible in Pt/Co/AlOx and Pt/Co/TbOx, where
+the Co layer can be oxidised or reduced, in Pt/Co/MgOx the effect has been
+found to be irreversible. We propose that these differences may be related to
+the different nature of the ionic conduction within the MOx layers.",2007.12570v1
+2020-07-24,Theroy of anisotropic plasmons,"We develop the complete theory for the collective plasmon modes of an
+interacting electron system in the presence of explicit mass (or velocity)
+anisotropy in the corresponding non-interacting situation, with the effective
+Fermi velocity being different along different axes. Such effective mass
+anisotropy is common in solid state materials (e.g., silicon or germanium),
+where the Fermi surface is often not spherical. We find that the plasmon
+dispersion itself develops significant anisotropy in such systems, and the
+commonly used isotropic approximation of using a density of states or optical
+effective mass does not work for the anisotropic system. We predict a
+qualitatively new phenomenon in anisotropic systems with no corresponding
+isotropic analog, where the plasmon mode along one direction decays into
+electron-hole pairs through Landau damping while the mode remains undamped and
+stable along a different directions",2007.12694v2
+2020-08-03,Anisotropic skyrmion bubbles in ultra-thin epitaxial Au$_{0.67}$Pt$_{0.33}$/Co/W films,"We studied the symmetry of magnetic properties and the resulting magnetic
+textures in ultra-thin epitaxial Au$_{0.67}$Pt$_{0.33}$/Co/W, a model system
+exhibiting perpendicular magnetic anisotropy and interface
+Dzyaloshinskii-Moriya interaction (DMI). As a peculiar feature, the
+C$_\mathrm{2v}$ crystal symmetry induced by the Co/W interface results in an
+additional uniaxial in-plane magnetic anisotropy in the cobalt layer.
+Photoemission electron microscopy with magnetic sensitivity reveals the
+formation of self-organized magnetic stripe domains oriented parallel to the
+hard in-plane magnetization axis. We attribute this behavior to the lower
+domain wall energy when oriented along this axis, where both the DMI and the
+in-plane magnetic anisotropy favor a N\'{e}el domain wall configuration. The
+anisotropic domain wall energy also leads to the formation of elliptical
+skyrmion bubbles in a weak out-of-plane magnetic field.",2008.00717v1
+2020-08-13,Isotropic or anisotropic screening in black phosphorous: can doping tip the balance?,"Black phosphorus (BP), a layered van der Waals (vdW) crystal, has unique
+in-plane band anisotropy and many resulting anisotropy properties such as the
+effective mass, electron mobility, optical absorption, thermal conductivity and
+plasmonic dispersion. However, whether anisotropic or isotropic charge
+screening exist in BP remains a controversial issue. Based on first-principles
+calculations, we study the screening properties in both of single-layer and
+bulk BP, especially concerning the role of doping. Without charge doping, the
+single-layer and bulk-phase BP show slight anisotropic screening. Electron and
+hole doping can increase the charge screening of BP and significantly change
+the relative static dielectric tensor elements along two different in-plane
+directions. We further study the charge density change induced by potassium (K)
+adatom near the BP surface, under different levels of charge doping. The
+calculated two-dimensional (2D) charge redistribution patterns also confirm
+that doping can greatly affect the screening feature and tip the balance
+between isotropic and anisotropic screening. We corroborate that screening in
+BP exhibit slight intrinsic anisotropy and doping has significant influence on
+its screening property.",2008.05761v1
+2020-09-01,Great enhancement of Curie temperature and magnetic anisotropy in two-dimensional van der Waals magnetic semiconductor heterostructures,"In two-dimensional (2D) magnetic systems, large magnetic anisotropy is needed
+to stabilize the magnetic order according to Mermin-Wagner theorem. Based on
+density functional theory (DFT) calculations, we propose that the magnetic
+anisotropic energy (MAE) of 2D ferromagnetic (FM) semiconductors can be
+strongly enhanced in van der Waals heterostructures by attaching a nonmagnetic
+semiconductor monolayer with large spin-orbit coupling. We studied
+Cr2Ge2Te6/PtSe2 bilayer heterostructures, where each layer has been realized in
+recent experiments. The DFT calculations show that the MAE of Cr2Ge2Te6/PtSe2
+is enhanced by 70%, and the Curie temperature TC is increased far beyond room
+temperature. A model Hamiltonian is suggested to analyze the DFT results,
+showing that both the Dzyaloshinskii-Moriya interaction and the single-ion
+anisotropy contribute to the enhancement of the MAE. Based on the superexchange
+picture, we find that the decreased energy difference between 3d orbitals of Cr
+and 5p orbitals of Te contributes partially to the increase of TC. Our present
+work indicates a promising way to enhance the MAE and TC by constructing van
+der Waals semiconductor heterostructures, which will inspire further studies on
+the 2D magnetic semiconductor systems.",2009.00317v1
+2020-09-11,Interplay between spatial anisotropy and further exchange interactions in the triangular Heisenberg model,"We investigate the interplay between spatial anisotropy and further exchange
+interactions in the spin-$\frac{1}{2}$ Heisenberg antiferromagnetic model on a
+triangular lattice. We use the Schwinger boson theory by including Gaussian
+fluctuations above the mean-field approach. The phase diagram exhibits a strong
+reduction of the long range collinear and incommensurate spirals regions with
+respect to the mean-field ones. This reduction is accompanied by the emergence
+of its short range order counterparts, leaving an ample room for $0$-flux and
+nematic spin liquid regions. Remarkably, within the neighborhood of the
+spatially isotropic line, there is a range where the spirals are so fragile
+that only the commensurate $120^{\circ}$ N\'eel ones survive. The good
+agreement with recent variational Monte Carlo predictions gives support to the
+rich phase diagram induced by spatial anisotropy.",2009.05447v1
+2020-09-14,Voltage-driven Magnetization Switching via Dirac Magnetic Anisotropy and Spin--orbit Torque in Topological-insulator-based Magnetic Heterostructures,"Electric-field control of magnetization dynamics is fundamentally and
+technologically important for future spintronic devices. Here, based on
+electric-field control of both magnetic anisotropy and spin--orbit torque, two
+distinct methods are presented for switching the magnetization in topological
+insulator (TI)/magnetic-TI hybrid systems. The magnetic anisotropy energy in
+magnetic TIs is formulated analytically as a function of the Fermi energy, and
+it is confirmed that the out-of-plane magnetization is always favored for the
+partially occupied surface band. Also proposed is a transistor-like device with
+the functionality of a nonvolatile magnetic memory that uses voltage-driven
+writing and the (quantum) anomalous Hall effect for readout. For the
+magnetization reversal, by using parameters of Cr-doped
+Bi_{1-x}Sb_{x})_{2}Te_{3}, the estimated source-drain current density and gate
+voltage are of the orders of $10^4$--$10^5$~A/cm$^2$ and 0.1~V, respectively,
+below 20~K and the writing requires no external magnetic field. Also discussed
+is the possibility of magnetization switching by the proposed method in
+TI/ferromagnetic-insulator bilayers with the magnetic proximity effect.",2009.06187v1
+2020-09-22,REPORT: Investigation on Curvilinear Anisotropy via Isogeometric Analysis (IGA),"The advent of multi-material additive manufacturing and automated composite
+manufacturing has enabled the design of structures featuring complex
+curvilinear anisotropy. To take advantage of the new design space, efficient
+computational approaches are quintessential. In this study, we explored a new
+NURBS-based Isogeometric Analysis (IGA) framework for the simulation of
+curvilinear fiber composites and we compared it to standard Finite Element
+Analysis (FEA). A plate featuring a semi-circular notch under tensile loading
+with different fiber configurations served as a case study. We showed that,
+thanks to the exact geometric representation and the enriched continuity
+between elements, NURBS-based IGA outperforms classical FEA in terms of
+computational efficiency, time-consumption, and estimation quality of field
+variables for same number of degrees-of-freedom. To further demonstrate the use
+of the IGA framework, we performed optimization studies aimed at identifying
+the fiber paths minimizing stress concentration and Tsai-Wu failure index. The
+model showed that curvilinear anisotropy can be effectively harnessed to reduce
+the stress concentration of up to 82 % compared to unidirectional composites
+without affecting the overall plate stiffness significantly.",2009.10230v3
+2020-10-07,Large anisotropies of the stochastic gravitational wave background from cosmic domain walls,"We investigate the stochastic gravitational wave background (SGWB) from
+cosmic domain walls (DWs) caused by quantum fluctuations of a light scalar
+field $\phi$ during inflation. Perturbations of $\phi$ remain almost constant
+after leaving the Hubble horizon. The probabilities of the two domains depend
+on the averaged value of $\phi$ at each large scale region, leading to large
+scale perturbations of DW energy density and large anisotropies in the SGWB. We
+find that the angular power spectrum is scale-invariant and at least of the
+order of $10^{-2}$, which is expected to be detected by future
+gravitational-wave (GW) detectors. Since we have not detected primordial GWs
+yet, anisotropies of the SGWB could help us to verify the rationality of
+inflation and determine the energy scale of inflation.",2010.03225v1
+2020-10-14,Interface-driven magnetic anisotropy in relaxed La$_{0.7}$Sr$_{0.3}$CrO$_3$/La$_{0.7}$Sr$_{0.3}$MnO$_3$ heterostructures on MgO,"We investigate the structural and magnetic properties of
+La$_{0.7}$Sr$_{0.3}$CrO$_3$ (LSCO)/La$_{0.7}$Sr$_{0.3}$MnO$_3$(LSMO)
+heterostructures grown on (001)-oriented MgO by molecular beam epitaxy. Due to
+the large film-substrate lattice mismatch, strain relaxation is found to occur
+within the first 2-3 unit cells (uc) of the film as evidenced by reflection
+high energy electron diffraction and high-resolution synchrotron X-ray
+reciprocal space mapping. We find that the presence of the LSCO spacer and
+capping layers leads to ferromagnetism in ultra-thin LSMO layers with
+thicknesses on the order of 2 uc with the magnetic easy axis oriented in the
+film plane. Net magnetic moments of 1.4 and 2.4 $\mu_B$/Mn are measured for [2
+uc LSCO/ 2 uc LSMO] and [2 uc LSCO/ 4 uc LSMO] superlattices, respectively by
+SQUID magnetometry. The effective magnetic anisotropy of the relaxed [2 uc
+LSCO/ 4 uc LSMO] heterostructure is found to be an order of magnitude higher
+than bulk LSMO highlighting the critical role of interfacial magnetic exchange
+interactions in tuning magnetic anisotropy at complex oxide interfaces.",2010.07180v1
+2020-10-08,The anisotropy in the optical constants of quartz crystals for soft X-rays,"The refractive index of a y-cut SiO$_2$ crystal surface is reconstructed from
+polarization dependent soft X-ray reflectometry measurements in the energy
+range from 45 eV to 620 eV. Due to the anisotropy of the crystal structure in
+the (100) and (001) directions, we observe a significant deviation of the
+measured reflectance at the Si-L$_{2,3}$ and O-K absorption edges. The
+anisotropy in the optical constants reconstructed from these data is also
+confirmed by ab initio Bethe-Salpeter Equation calculations of the O-K edge.
+This new experimental dataset expands the existing literature data for quartz
+optical constants significantly, particularly in the near-edge regions.",2010.09436v1
+2020-11-06,Gigantic magnetochiral anisotropy in the topological semimetal ZrTe5,"Topological materials with broken inversion symmetry can give rise to
+nonreciprocal responses, such as the current rectification controlled by
+magnetic fields via magnetochiral anisotropy. Bulk nonreciprocal responses
+usually stem from relativistic corrections and are always very small. Here we
+report our discovery that ZrTe5 crystals in proximity to a topological quantum
+phase transition present gigantic magnetochiral anisotropy, which is the
+largest ever observed to date. We argue that a very low carrier density,
+inhomogeneities, and a torus-shaped Fermi surface induced by breaking of
+inversion symmetry in a Dirac material are central to explain this
+extraordinary property.",2011.03329v3
+2020-11-13,Resolving Multiphoton Processes with High-Order Anisotropy Ultrafast X-ray Scattering,"We present first results on ultrafast X-ray scattering of strongly driven
+molecular Iodine and analysis of high-order anisotropic components of the
+scattering signal, up to four-photon absorption. We discuss the technical
+details of retrieving high fidelity high-order anisotropy components, and
+outline a method to analyze the scattering signal using Legendre decomposition.
+We use simulated anisotropic scattering signals and Fourier analysis to map how
+anisotropic dissociation motions can be extracted from the various Legendre
+orders. We observe multitude dissociation and vibration motions simultaneously
+arising from various multiphoton transitions. We use the anisotropy information
+of the scattering signal to disentangle the different processes and assign
+their dissociation velocities on the Angstrom and femtosecond scales de-novo.",2011.06761v3
+2020-11-24,Temperature dependence of London penetration depth anisotropy in superconductors with anisotropic order parameters,"We study the effects of anisotropic order parameters on the temperature
+dependence of London penetration depth anisotropy $\gamma_\lambda(T)$. After
+MgB$_2$, this dependence is commonly attributed to distinct gaps on multi-band
+Fermi surfaces in superconductors. We have found, however, that the anisotropy
+parameter may depend on temperature also in one-band materials with anisotropic
+order parameters $\Delta(T,k_F)$, a few such examples are given. We have found
+also that for different order parameters, the temperature dependence of
+$\Delta(T)/\Delta(0)$ can be represented with good accuracy by the
+interpolation suggested by D. Einzel, J. Low Temp. Phys, {\bf 131}, 1 (2003),
+which simplifies considerably the evaluation of $\gamma_\lambda(T)$. Of
+particular interest is mixed order parameters of two symmetries for which
+$\gamma_\lambda(T)$ may go through a maximum for a certain relative weight of
+two phases. Also, for this case, we find that the ratio $\Delta_{max}(0)/T_c$
+may exceed substantially the weak coupling limit of 1.76. It, however, does not
+imply a strong coupling, rather it is due to significantly anisotropic angular
+variation of $\Delta$.",2011.12412v1
+2020-11-27,"Pinning, flux flow resistivity and anisotropy of Fe(Se,Te) thin films from microwave measurements through a bitonal dielectric resonator","We report on the anisotropy of the vortex motion surface impedance of a \fst
+thin film grown on a CaF$_2$ substrate. The dependence on the magnetic field
+intensity up to 1.2 T and direction, both parallel and perpendicular to the
+sample $c$-axis, was explored at fixed temperature at two distinct frequencies,
+$\sim16\;$GHz and $\sim27\;$GHz, by means of bitonal dielectric resonator. The
+free flux flow resistivity $\rho_{ff}$ was obtained by exploiting standard
+models for the high frequency dynamics, whereas the angle dependence was
+studied in the framework of the well known and widely used
+Blatter-Geshkenbein-Larkin (BGL) scaling theory for anistropic superconductors.
+Excellent agreement with the scaling law prescription by the fluxon flux flow
+resistivity was obtained. From the scaling analysis, a low-field mass
+anisotropy $\sim1.8$ was obtained, well within the value ranges reported in
+literature. The angular dependence of the pinning constant suggests that
+pinning is dominated by random, isotropic point pins, consistently with
+critical current density measurements.",2011.13819v1
+2020-12-03,MoS$_2$ flake as a van der Waals homostructure: luminescence properties and optical anisotropy,"We investigated multilayer plates made by exfoliation from a high-quality
+MoS$_2$ crystal and reveal that they represent a new object - van der Waals
+homostructure consisting of a bulk core and a few detached monolayers on its
+surface. This architecture comprising elements with different electron band
+structure leads to specific luminescence, when the broad emission band from the
+core is cut by the absorption peaks of strong exciton resonances in the surface
+monolayers. The exfoliated flakes exhibit strong optical anisotropy. We have
+observed a conversion of normally incident light polarization to $15\%$ in
+transmission geometry. This background effect is due to fluctuations of the c
+axis relative to the normal, whereas the pronounced resonance contribution is
+explained by the polarization anisotropy of excitons localized in the stripes
+of dissected surface monolayers.",2012.02032v2
+2020-12-06,On anisotropy and inhomogeneity parameter estimation using traveltimes,"We consider an anisotropic inhomogeneous model to simulate measured
+vertical-seismic-profile traveltimes. In this model, we assume that velocity
+increases linearly with depth and anisotropy is the result of elliptical
+velocity dependence. Using a series of sources in a line to a single receiver,
+we minimize the least-squares residual between measured and modelled
+traveltimes to estimate the anisotropy and inhomogeneity parameters of the
+subsurface. To verify the approach, we construct synthetic traveltime data for
+a one- and two-layer model and perform the traveltime inversion. We justify the
+convergence-ensuring specifications and model-parameter restrictions that are
+intrinsic to the parameter estimation. To determine the approach's
+practicality, we assess the reliability of results under the influence of
+noise. From this assessment, we discern the noise threshold for both models and
+determine that the noise restriction is severely restrictive for increasing
+model complexity. We estimate parameters, using the same methodology, for a
+real-data case and conclude with a discussion of results.",2012.03393v1
+2020-12-07,Cross-correlations as a Diagnostic Tool for Primordial Gravitational Waves,"We explore and corroborate, by working out explicit examples, the
+effectiveness of cross-correlating stochastic gravitational wave background
+anisotropies with CMB temperature fluctuations as a way to establish the
+primordial nature of a given gravitational wave signal. We consider the case of
+gravitational wave anisotropies induced by scalar-tensor-tensor primordial
+non-Gaussianity. Our analysis spans anisotropies exhibiting different angular
+behaviours, including a quadrupolar dependence. We calculate the expected
+uncertainty on the non-linearity parameter $F_{\rm NL}$ obtained as a result of
+cross-correlation measurements for several proposed experiments such as the
+ground-based Einstein Telescope, Cosmic Explorer, and the space-based Big-Bang
+Observer. As a benchmark for future survey planning, we also calculate the
+theoretical, cosmic-variance-limited, error on the non-linearity parameter.",2012.03498v2
+2020-12-07,Magnetic anisotropy from linear defect structures in correlated electron systems,"Correlated electron systems, particularly iron-based superconductors, are
+extremely sensitive to strain, which inevitably occurs in the crystal growth
+process. Built-in strain of this type has been proposed as a possible
+explanation for experiments where nematic order has been observed at high
+temperatures corresponding to the nominally tetragonal phase of iron-based
+superconductors. Strain is assumed to produce linear defect structures, e.g.
+dislocations, which are quite similar to O vacancy chainlets in the underdoped
+cuprate superconductor YBCO. Here we investigate a simple microscopic model of
+dislocations in the presence of electronic correlations, which create defect
+states that can drive magnetic anisotropy of this kind, if spin orbit
+interaction is present. We estimate the contribution of these dislocations to
+magnetic anisotropy as detected by current torque magnetometry experiments in
+both cuprates and Fe-based systems.",2012.03824v2
+2020-12-15,Thermodynamically stable skyrmion lattice in tetragonal frustrated antiferromagnet with dipolar interaction,"Motivated by recent experimental results on GdRu$_2$Si$_2$ [Khanh, N.D.,
+Nakajima, T., Yu, X. et al., \emph{Nat. Nanotechnol.} \textbf{15}, 444-449
+(2020)], where nanometric square skyrmion lattice was observed, we propose
+simple analytical mean-field description of the high-temperature part of the
+phase diagram of centrosymmetric tetragonal frustrated antiferromagnets with
+dipolar interaction in the external magnetic field. In the reciprocal space
+dipolar forces provide momentum dependent biaxial anisotropy. It is shown that
+in tetragonal lattice in the large part of the Brillouin zone for mutually
+perpendicular modulation vectors in the $ab$ plane this anisotropy has mutually
+perpendicular easy axes and collinear middle axes, what leads to double-Q
+modulated spin structure stabilization. The latter turns out to be a square
+skyrmion lattice in the large part of its stability region with the topological
+charge $\pm 1$ per magnetic unit cell, which is determined by the frustrated
+exchange coupling, and, thus, nanometer-sized. In the presence of additional
+single-ion easy-axis anisotropy, easy and middle axes can be swapped, which
+leads to different phase diagram. It is argued that the latter case is relevant
+to GdRu$_2$Si$_2$.",2012.08422v1
+2020-12-23,Effect of Fullerene on domain size and relaxation in a perpendicularly magnetized Pt/Co/C60/Pt system,"Buckminsterfullerene (C60) can exhibit ferromagnetism at the interface
+(called as a spinterface) when it is placed next to a ferromagnet (FM).
+Formation of such spinterface happens due to orbital hybridization and spin
+polarized charge transfer at the interface. The spinterface can influence the
+domain size and dynamics of the organic/ferromagnetic heterostructure. Here, we
+have performed magnetic domain imaging and studied the relaxation dynamics in
+Pt/Co/C60/Pt system with perpendicular anisotropy. We have compared the results
+with its parent Pt/Co/Pt system. It is observed that presence of C60 in the
+Pt/Co/Pt system increases the anisotropy and a decrease in the bubble domain
+size. Further the switching time of Pt/Co/C60/Pt system is almost two times
+faster than Pt/Co/Pt system. We have also performed the spin polarized density
+functional theory (DFT) calculations to understand the underneath mechanism.
+DFT results show formation of a spin polarized spinterface which leads to an
+enhancement in anisotropy.",2012.12777v3
+2020-12-28,A study on the effect of anisotropy under Finch-Skea geometry,"The popularity of the Finch-Skea ansatz to describe relativistic stellar
+model have encouraged us to study the analytic solutions of the Einstein field
+equation. We have presented a class of exact solutions to the field equations
+after considering the corresponding two cases: (i) positive value of
+anisotropic parameter, and (ii) absence of any anisotropy. Smooth matching of
+the interior solutions with the Schwarzschild exterior solution helped us to
+determine constants. The physical features of the solutions thus obtained have
+been studied both graphically and numerically with the specific pulsar
+$4U~1608-52$ (Mass = $1.57^{+0.30}_{-0.29}~M_\odot$ and radius = $9.8\pm
+1.8~km$). The stability conditions for the model have also been discussed,
+however the model is found to be stable for zero anisotropy.",2012.14085v2
+2021-01-04,Reconstructing Patchy Reionization with Deep Learning,"The precision anticipated from next-generation cosmic microwave background
+(CMB) surveys will create opportunities for characteristically new insights
+into cosmology. Secondary anisotropies of the CMB will have an increased
+importance in forthcoming surveys, due both to the cosmological information
+they encode and the role they play in obscuring our view of the primary
+fluctuations. Quadratic estimators have become the standard tools for
+reconstructing the fields that distort the primary CMB and produce secondary
+anisotropies. While successful for lensing reconstruction with current data,
+quadratic estimators will be sub-optimal for the reconstruction of lensing and
+other effects at the expected sensitivity of the upcoming CMB surveys. In this
+paper we describe a convolutional neural network, ResUNet-CMB, that is capable
+of the simultaneous reconstruction of two sources of secondary CMB
+anisotropies, gravitational lensing and patchy reionization. We show that the
+ResUNet-CMB network significantly outperforms the quadratic estimator at low
+noise levels and is not subject to the lensing-induced bias on the patchy
+reionization reconstruction that would be present with a straightforward
+application of the quadratic estimator.",2101.01214v2
+2021-01-27,Strong In-plane Anisotropy in the Electronic Properties of Doped Transition Metal Dichalcogenides exhibited in W1-xNbxS2,"In this work, we study the electronic properties of monolayer transition
+metal dichalcogenide materials subjected to aliovalent doping, using Nb-doped
+WS2 as an exemplar. Scanning transmission electron microscopy imaging of the
+as-grown samples reveals an anisotropic Nb dopant distribution, prompting our
+investigation of anisotropy in electronic properties. Through electronic
+structure calculations on supercells representative of observed structures, we
+confirm that local Nb-atom distributions are consistent with energetic
+considerations, although kinetic processes occurring during sample growth must
+be invoked to explain the overall symmetry-breaking. We perform effective
+bandstructure and conductivity calculations on realistic models of the material
+that demonstrate that a high level of anisotropy can be expected in electronic
+properties including conductivity and mobility.",2101.11687v3
+2021-02-05,Symmetry-Driven Spin-Wave Gap Modulation in Nanolayered SrRuO3/SrTiO3 Heterostructures: Implications for Spintronic Applications,"A strong correlation between magnetic interaction and topological symmetries
+leads to unconventional magneto-transport behavior. Weyl fermions induce
+topologically protected spin-momentum locking, which is closely related to
+spin-wave gap formation in magnetic crystals. Ferromagnetic SrRuO3, regarded as
+a strong candidate for Weyl semimetal, inherently possesses a nonzero spin-wave
+gap owing to its strong magnetic anisotropy. In this paper, we propose a method
+to control the spin-wave dynamics by nanolayer designing of the SrRuO3/SrTiO3
+superlattices. In particular, the six-unit-cell-thick SrRuO3 layers within the
+superlattices undergo a phase transition in crystalline symmetry from
+orthorhombic to tetragonal, as the thickness of the SrTiO3 layers is modulated
+with atomic-scale precision. Consequently, the magnetic anisotropy, anomalous
+Hall conductivity, and spin-wave gap could be systematically manipulated. Such
+customization of magnetic anisotropy via nanoscale heterostructuring offers a
+novel control knob to tailor the magnon excitation energy for future spintronic
+applications, including magnon waveguides and filters. Our nanolayer approach
+unveils the important correlation between the tunable lattice degrees of
+freedom and spin dynamics in topologically non-trivial magnetic materials.",2102.03008v1
+2021-02-10,Measuring magnetization with rotation measures and velocity centroids in supersonic MHD turbulence,"The interstellar turbulence is magnetized and thus anisotropic. The
+anisotropy of turbulent magnetic fields and velocities is imprinted in the
+related observables, rotation measures (RMs), and velocity centroids (VCs).
+This anisotropy provides valuable information on both the direction and
+strength of the magnetic field. However, its measurement is difficult
+especially in highly supersonic turbulence in cold interstellar phases due to
+the distortions by isotropic density fluctuations. By using 3D simulations of
+supersonic and sub-Alfv\'enic magnetohydrodynamic(MHD) turbulence, we find that
+the problem can be alleviated when we selectively sample the volume-filling
+low-density regions in supersonic MHD turbulence. Our results show that in
+these low-density regions, the anisotropy of RM and VC fluctuations depends on
+the Alfv\'enic Mach number as $\rm M_A^{-4/3}$. This anisotropy-$\rm M_A$
+relation is theoretically expected for sub-Alfv 'enic MHD turbulence and
+confirmed by our synthetic observations of $^{12}$CO emission. It provides a
+new method for measuring the plane-of-the-sky magnetic fields in cold
+interstellar phases.",2102.05647v1
+2021-02-19,Revealing the intrinsic superconducting gap anisotropy in surface-neutralized BaFe$_2$(As$_{0.7}$P$_{0.3}$)$_2$,"Alkaline-earth iron arsenide (122) is one of the most studied families of
+iron-based superconductors, especially for angle-resolved photoemission
+spectroscopy. While extensive photoemission results have been obtained, the
+surface complexity of 122 caused by its charge-non-neutral surface is rarely
+considered. Here, we show that the surface of 122 can be neutralized by
+potassium deposition. In potassium-coated BaFe$_2$(As$_{0.7}$P$_{0.3}$)$_2$,
+the surface-induced spectral broadening is strongly suppressed, and hence the
+coherent spectra that reflect the intrinsic bulk electronic state recover. This
+enables the measuring of superconducting gap with unpreceded precision. The
+result shows the existence of two pairing channels. While the gap anisotropy on
+the outer hole/electron pockets can be well fitted using an s$_\pm$ gap
+function, the gap anisotropy on the inner hole/electron shows a clear
+deviation. Our results provide quantitative constraints for refining
+theoretical models and also demonstrate an experimental method for revealing
+the intrinsic electronic properties of 122 in future studies.",2102.09919v1
+2021-02-22,Exact Critical Casimir Amplitude of Anisotropic Systems from Conformal Field Theory and Self-Similarity of Finite-Size Scaling Functions in $d\geq 2$ Dimensions,"The exact critical Casimir amplitude is derived for anisotropic systems
+within the $d=2$ Ising universality class by combining conformal field theory
+(CFT) with anisotropic $\varphi^4$ theory. Explicit results are presented for
+the general anisotropic scalar $\varphi^4$ model and for the fully anisotropic
+triangular-lattice Ising model in finite rectangular and infinite strip
+geometries with periodic boundary conditions (PBC). These results demonstrate
+the validity of multiparameter universality for confined anisotropic systems
+and the nonuniversality of the critical Casimir amplitude. We find an
+unexpected complex form of self-similarity of the anisotropy effects near the
+instability where weak anisotropy breaks down. This can be traced back to the
+property of modular invariance of isotropic CFT for $d=2$. More generally, for
+$d>2$ we predict the existence of self-similar structures of the finite-size
+scaling functions of $O(n)$-symmetric systems with planar anisotropies and PBC
+both in the critical region for $ n \geq 1$ as well as in the
+Goldstone-dominated low-temperature region for $ n \geq 2$.",2102.11214v2
+2021-02-25,Magnetic anisotropy in Fe/U and Ni/U bilayers,"Magnetometry measurements of Fe/U and Ni/U bilayer systems reveal a
+non-monotonic dependence of the magnetic anisotropy for U thicknesses in the
+range 0 nm - 8 nm, with the Fe/U bilayers showing a more prominent effect as
+compared to Ni/U. The stronger response for Fe/U is ascribed to the stronger
+3d-5f hybridization of Fe and U. This non-monotonic behaviour is thought to
+arise from quantum well states in the uranium overlayers. Estimating an
+oscillation period from the non-monotonic data, and comparing it to Density
+Functional Theory calculations, we find that wavevector matches to the
+experimental data can be made to regions of high spectral density in (010) and
+(100) cuts of the electronic structure of{\alpha}-U, consistent with the
+measured texture in the films. Unexpectedly, there are also indications of
+perpendicular magnetic anisotropy in a subset of Fe/U samples at relatively
+large U thickness.",2102.12784v1
+2021-02-26,Crossover from itinerant to localized states in the thermoelectric oxide [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$],"The layered cobaltite [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$], often expressed as
+the approximate formula Ca$_3$Co$_4$O$_9$, is a promising candidate for
+efficient oxide thermoelectrics but an origin of its unusual thermoelectric
+transport is still in debate. Here we investigate \textit{in-plane} anisotropy
+of the transport properties in a broad temperature range to examine the
+detailed conduction mechanism. The in-plane anisotropy between $a$ and $b$ axes
+is clearly observed both in the resistivity and the thermopower, which is
+qualitatively understood with a simple band structure of the triangular lattice
+of Co ions derived from the angle-resolved photoemission spectroscopy
+experiments. On the other hand, at high temperatures, the anisotropy becomes
+smaller and the resistivity shows a temperature-independent behavior, both of
+which indicate a hopping conduction of localized carriers. Thus the present
+observations reveal a crossover from low-temperature itinerant to
+high-temperature localized states, signifying both characters for the enhanced
+thermopower.",2102.13250v1
+2021-03-03,Skyrmion Logic Clocked via Voltage Controlled Magnetic Anisotropy,"Magnetic skyrmions are exciting candidates for energy-efficient computing due
+to their non-volatility, detectability,and mobility. A recent proposal within
+the paradigm of reversible computing enables large-scale circuits composed
+ofdirectly-cascaded skyrmion logic gates, but it is limited by the
+manufacturing difficulty and energy costs associated withthe use of notches for
+skyrmion synchronization. To overcome these challenges, we therefore propose a
+skyrmion logicsynchronized via modulation of voltage-controlled magnetic
+anisotropy (VCMA). In addition to demonstrating theprinciple of VCMA
+synchronization through micromagnetic simulations, we also quantify the impacts
+of current den-sity, skyrmion velocity, and anisotropy barrier height on
+skyrmion motion. Further micromagnetic results demonstratethe feasibility of
+cascaded logic circuits in which VCMA synchronizers enable clocking and
+pipelining, illustrating afeasible pathway toward energy-efficient large-scale
+computing systems based on magnetic skyrmions.",2103.02724v2
+2021-03-11,"Perpendicular magnetic anisotropy at Fe/Au(111) interface studied by Mössbauer, x-ray absorption, and photoemission spectroscopies","The origin of the interfacial perpendicular magnetic anisotropy (PMA) induced
+in the ultrathin Fe layer on the Au(111) surface was examined using
+synchrotron-radiation-based M\""{o}ssbauer spectroscopy (MS), X-ray magnetic
+circular dichroism (XMCD), and angle-resolved photoemission spectroscopy
+(ARPES). To probe the detailed interfacial electronic structure of orbital
+hybridization between the Fe 3$d$ and Au 6$p$ bands, we detected the
+interfacial proximity effect, which modulates the valence-band electronic
+structure of Fe, resulting in PMA. MS and XMCD measurements were used to detect
+the interfacial magnetic structure and anisotropy in orbital magnetic moments,
+respectively. $In$-$situ$ ARPES also confirms the initial growth of Fe on large
+spin-orbit coupled surface Shockley states under Au(111) modulated electronic
+states in the vicinity of the Fermi level. This suggests that PMA in the
+Fe/Au(111) interface originates from the cooperation effects among the spin,
+orbital magnetic moments in Fe, and large spin-orbit coupling in Au. These
+findings pave the way to develop interfacial PMA using $p$-$d$ hybridization
+with a large spin-orbit interaction.",2103.06572v1
+2021-03-23,Induced side-branching in smooth and faceted dendrites: theory and Phase-Field simulations,"The present work is devoted to the phenomenon of induced side branching
+stemming from the disruption of free dendrite growth. Therein, we postulate
+that the secondary branching instability can be triggered by the departure of
+the morphology of the dendrite from its steady state shape. Thence, the
+instability results from the thermodynamic trade-off between non monotonic
+variations of interface temperature, surface energy, kinetic anisotropy and
+interface velocity within the Gibbs Thomson equation. For purposes of
+illustration, the toy model of capillary anisotropy modulation is prospected
+both analytically and numerically by means of phase field simulations. It is
+evidenced that side branching can befall both smooth and faceted dendrites, at
+a normal angle from the front tip which is specific to the nature of the
+capillary anisotropy shift applied.",2103.12400v1
+2021-04-07,Anisotropic Turbulence in Position-Position-Velocity Space: Probing Three-Dimensional Magnetic Fields,"Direct measurements of three-dimensional magnetic fields in the interstellar
+medium (ISM) are not achievable. However, the anisotropic nature of
+magnetohydrodynamic (MHD) turbulence provides a novel way of tracing the
+magnetic fields. Guided by the advanced understanding of turbulence's
+anisotropy in the Position-Position-Velocity (PPV) space, we extend the
+Structure-Function Analysis (SFA) to measure both the three-dimensional
+magnetic field orientation and Alfven Mach number $M_A$, which provides the
+information on magnetic field strength. Following the theoretical framework
+developed in Kandel et al. (2016), we find that the anisotropy in a given
+velocity channel is affected by the inclination angle between the 3D magnetic
+field direction and the line-of-sight as well as media magnetization. We
+analyze the synthetic PPV cubes generated by incompressible and compressible
+MHD simulations. We confirm that the PPV channel's intensity fluctuations
+measured in various position angles reveal plane-of-the-sky magnetic field
+orientation. We show that by varying the channel width, the anisotropies of the
+intensity fluctuations in PPV space can be used to simultaneously estimate both
+magnetic field inclination angle and strength of total magnetic fields.",2104.02842v2
+2021-04-07,Switchable Rashba Anisotropy in Two-dimensional Hybrid Organic-Inorganic Perovskite by Hybrid Improper Ferroelectricity,"Two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs) are
+introducing new directions in the 2D materials landscape. The coexistence of
+ferroelectricity and spin-orbit interactions play a key role in their
+optoelectronic properties. We perform a detailed study on a recently
+synthesized ferroelectric 2D-HOIP, (AMP)PbI$_4$ (AMP =
+4-aminomethyl-piperidinium). The calculated polarization and Rashba parameter
+are in excellent agreement with experimental values. We report a striking new
+effect, i.e., an extraordinarily large Rashba anisotropy that is tunable by
+ferroelectric polarization: as polarization is reversed, not only the spin
+texture chirality is inverted, but also the major and minor axes of the Rashba
+anisotropy ellipse in k-space are interchanged - a pseudo rotation. A $k \cdot
+p$ model Hamiltonian and symmetry-mode analysis reveal a quadrilinear coupling
+between the cation-rotation modes responsible for the Rashba ellipse
+pseudo-rotation, the framework rotation, and the polarization. These findings
+may provide new avenues for spin-optoelectronic devices such as spin valves or
+spin FETs.",2104.02970v1
+2021-04-07,Analytical results for the low-temperature Drude weight of the XXZ spin chain,"The spin-$1/2$ XXZ chain is an integrable lattice model and parts of its spin
+current can be protected by local conservation laws for anisotropies
+$-1<\Delta<1$. In this case, the Drude weight $D(T)$ is non-zero at finite
+temperatures $T$. Here we obtain analytical results for $D(T)$ at low
+temperatures for zero external magnetic field and anisotropies
+$\Delta=\cos(n\pi/m)$ with $n,m$ coprime integers, using the thermodynamic
+Bethe ansatz. We show that to leading orders
+$D(T)=D(0)-a(\Delta)T^{2K-2}-b_1(\Delta)T^2$ where $K$ is the Luttinger
+parameter and the prefactor $a(\Delta)$, obtained in closed form, has a fractal
+structure as function of anisotropy $\Delta$. The prefactor $b_1(\Delta)$, on
+the other hand, does not have a fractal structure and can be obtained in a
+standard field-theoretical approach. Including both temperature corrections, we
+obtain an analytic result for the low-temperature asymptotics of the Drude
+weight in the entire regime $-1<\Delta=\cos(n\pi/m)<1$.",2104.03266v1
+2021-04-15,Dyakonov surface waves in dielectric crystals with negative anisotropy,"We report the prediction of a new type of Dyakonov surface waves that
+propagate along the flat strip of the interface between two dielectrics with
+negative anisotropy. It is shown that the surface waves condition is satisfied
+for negatively anisotropic dielectrics due to specific boundaries of the strip
+waveguide confined between two metallic plates. Such modes are studied by the
+perturbation theory in the approximation of weak anisotropy. The existence of
+Dyakonov surface waves in negative uniaxial crystals motivates us to reconsider
+the list of materials suitable for their practical implementation. We believe
+that this work opens a new unexplored research area in the field of surface
+waves.",2104.07394v1
+2021-04-22,Low Anisotropy Sense Retrofitting (LASeR) : Towards Isotropic and Sense Enriched Representations,"Contextual word representation models have shown massive improvements on a
+multitude of NLP tasks, yet their word sense disambiguation capabilities remain
+poorly explained. To address this gap, we assess whether contextual word
+representations extracted from deep pretrained language models create
+distinguishable representations for different senses of a given word. We
+analyze the representation geometry and find that most layers of deep
+pretrained language models create highly anisotropic representations, pointing
+towards the existence of representation degeneration problem in contextual word
+representations. After accounting for anisotropy, our study further reveals
+that there is variability in sense learning capabilities across different
+language models. Finally, we propose LASeR, a 'Low Anisotropy Sense
+Retrofitting' approach that renders off-the-shelf representations isotropic and
+semantically more meaningful, resolving the representation degeneration problem
+as a post-processing step, and conducting sense-enrichment of contextualized
+representations extracted from deep neural language models.",2104.10833v1
+2021-04-27,Stability of Mn2RuxGa-based Multilayer Stacks,"Perpendicular heterostructures based on a ferrimagnetic Mn2RuxGa (MRG) layer
+and a ferromagnetic Co/Pt multilayer were examined to understand the effects of
+different spacer layers (V, Mo, Hf, HfOx and TiN) on the interfaces with the
+magnetic electrodes, after annealing at 350 C. Loss of perpendicular anisotropy
+in MRG is strongly correlated with a reduction in the substrate-induced
+tetragonality due to relaxation of the crystal structure. In the absence of
+diffusion, strain and chemical ordering within MRG are correlated. The limited
+solubility of both Hf and Mo in MRG is a source of additional valence
+electrons, which results in an increase in compensation temperature Tcomp. This
+also stabilises perpendicular anisotropy, compensating for changes in strain
+and defect density. The reduction in squareness of the MRG hysteresis loop
+measured by anomalous Hall effect is <10 %, making it useful in active devices.
+Furthermore, a CoPt3 phase with (2 2 0) texture in the perpendicular Co/Pt free
+layer promoted by a Mo spacer layer is the only one that retains its
+perpendicular anisotropy on annealing.",2104.13319v2
+2021-05-25,Dynamics of particles with cubic magnetic anisotropy in a viscous liquid,"The specific absorption rate (SAR) of a dilute assembly of spherical iron
+nanoparticles with cubic anisotropy distributed in a viscous liquid is
+calculated using the solution of stochastic Landau - Lifshitz equation for unit
+magnetization vector and stochastic equations for multiple particle directors
+that specify the spatial orientation of the nanoparticle in a liquid. The
+viscous and magnetic magnetization reversal modes of particles are revealed at
+low and sufficiently high amplitudes of alternating magnetic field,
+respectively. The SAR of iron nanoparticle assembly is shown to exceed
+significantly that of iron oxide nanoparticles with uniaxial anisotropy at the
+same amplitudes and frequencies of applied magnetic field. The linear response
+theory is shown to be valid only at small magnetic field amplitudes, H0 < 50 -
+70 Oe.",2105.11916v1
+2021-05-27,Optimal control of anisotropic Allen-Cahn equations,"This paper aims at solving an optimal control problem governed by an
+anisotropic Allen-Cahn equation numerically. Therefore we first prove the
+Fr\'echet differentiability of an in time discretized parabolic control problem
+under certain assumptions on the involved quasilinearity and formulate the
+first order necessary conditions. As a next step, since the anisotropies are in
+general not smooth enough, the convergence behavior of the optimal controls are
+studied for a sequence of (smooth) approximations of the former quasilinear
+term. In addition the simultaneous limit in the approximation and the time step
+size is considered. For a class covering a large variety of anisotropies we
+introduce a certain regularization and show the previously formulated
+requirements. Finally, a trust region Newton solver is applied to various
+anisotropies and configurations, and numerical evidence for mesh independent
+behavior and convergence with respect to regularization is presented.",2105.13310v3
+2021-05-27,Compact stellar model in presence of pressure anisotropy in modified Finch Skea spacetime,"A new model of anisotropic compact star is obtained in our present paper by
+assuming the pressure anisotropy. The proposed model is singularity free. The
+model is obtained by considering a physically reasonable choice for the metric
+potential $g_{rr}$ which depends on a dimensionless parameter `n'. The effect
+of $n$ is discussed numerically, analytically and through plotting. We have
+concentrated a wide range for n ($10\leq n \leq 1000$) for drawing the profiles
+of different physical parameters. The maximum allowable mass for different
+values of $n$ have been obtained by M-R plot. We have checked that the
+stability of the model is increased for larger value of $n$. For the viability
+of the model we have considered two compact stars PSR J1614-2230 and EXO
+1785-248. We have shown that the expressions for the anisotropy factor and the
+metric component may serve as generating functions for uncharged stellar models
+in the context of the general theory of relativity.",2106.01316v1
+2021-06-07,Probing pre-Recombination Physics by the Cross-Correlation of Stochastic Gravitational Waves and CMB Anisotropies,"We study the effects of pre-recombination physics on the Stochastic
+Gravitational Wave Background (SGWB) anisotropies induced by the propagation of
+gravitons through the large-scale density perturbations and their
+cross-correlation with Cosmic Microwave Background (CMB) temperature and E-mode
+polarization ones. As examples of Early Universe extensions to the $\Lambda$CDM
+model, we consider popular models featuring extra relativistic degrees of
+freedom, a massless non-minimally coupled scalar field, and an Early Dark
+Energy component. Assuming the detection of a SGWB, we perform a Fisher
+analysis to assess in a quantitative way the capability of future gravitational
+wave interferometers (GWIs) in conjunction with a future large-scale CMB
+polarization experiment to constrain such variations. Our results show that the
+cross-correlation of CMB and SGWB anisotropies will help tighten the
+constraints obtained with CMB alone, with an improvement that significantly
+depends on the specific model as well as the maximum angular resolution
+$\ell_{\rm max}^{\rm GW}$ of the GWIs, their designed sensitivity, and the
+amplitude $A_*$ of the monopole of the SGWB.",2106.03786v2
+2021-06-10,Steering visible Dyakonov surface waves at the hyperbolic metasurface,"Dyakonov surface wave existing at the interface with anisotropy offers a
+promising way of guiding light in two-dimension with almost no loss. However,
+predicted decades ago, the experimental demonstration of the Dyakonov surface
+wave seems always challenging for the weak anisotropic indices from the natural
+materials. Here we experimentally demonstrated a Dyakonov surface wave mode
+propagating in a hyperbolic metasurface at the visible frequency. Dyakonov
+surface waves at the two surfaces of the metasurface can be supported
+simultaneously by the hyperbolic anisotropy and form a Dyakonov typed mode with
+low loss and a large allowed angle band. A detailed theoretical analysis and
+numerical simulations prove that the electric field of such a surface wave mode
+shows transverse spin, whose direction is determined by the orientations of the
+hyperbolic anisotropy and surface normal, based on which we experimentally
+observed the photonic spin Hall effect of the surface wave mode in our
+metasurface.",2106.05699v1
+2021-06-13,Morphology of an interacting three-dimensional trapped Bose-Einstein condensate from many-particle variance anisotropy,"The variance of the position operator is associated with how wide or narrow a
+wave-packet is, the momentum variance is similarly correlated with the size of
+a wave-packet in momentum space, and the angular-momentum variance quantifies
+to what extent a wave-packet is non-spherically symmetric. We examine an
+interacting three-dimensional trapped Bose-Einstein condensate at the limit of
+an infinite number of particles, and investigate its position, momentum, and
+angular-momentum anisotropies. Computing the variances of the three Cartesian
+components of the position, momentum, and angular-momentum operators we present
+simple scenarios where the anisotropy of a Bose-Einstein condensate is
+different at the many-body and mean-field levels of theory, despite having the
+same many-body and mean-field densities per particle. This suggests a way to
+classify correlations via the morphology of 100\% condensed bosons in a
+three-dimensional trap at the limit of an infinite number of particles.
+Implications are briefly discussed.",2106.07001v1
+2021-06-18,Exchange bias without directional anisotropy in Permalloy/CoO bilayers,"We utilize transverse ac susceptibility measurements to characterize magnetic
+anisotropy in archetypal exchange-bias bilayers of ferromagnet Permalloy (Py)
+and antiferromagnet CoO. Unidirectional anisotropy is observed for thin Py, but
+becomes negligible at larger Py thicknesses, even though the directional
+asymmetry of the magnetic hysteresis loop remains significant. Additional
+magnetoelectronic measurements, magneto-optical imaging, as well as
+micromagnetic simulations show that these surprising behaviors are likely
+associated with asymmetry of spin flop distribution created in CoO during Py
+magnetization reversal, which facilitates the rotation of the latter back into
+its field-cooled direction. Our findings suggest new possibilities for
+efficient realization of multistable nanomagnetic systems for neuromorphic
+applications.",2106.09924v1
+2021-06-20,Genuine tripartite entanglement as a probe of quantum phase transitions in a spin-1 Heisenberg chain with single-ion anisotropy,"We study the quantum phase transitions of spin-1 Heisenberg chains with an
+easy-axis anisotropy $\Delta$ and a uniaxial single-ion anisotropy $D$ using a
+multipartite entanglement approach. The genuine tripartite entanglement between
+the spin blocks, measured by the tripartite qutrit hyperdeterminant, is
+calculated within the quantum renormalization group method. Using this
+approach, the phase boundaries between the topological Haldane, large-D and
+anti-ferromagnetic N\'eel phases are determined in the half $\Delta-D$ plane
+with $\Delta>0$. When the size of the spin blocks increases, the genuine
+tripartite entanglement between the blocks exhibits a nonzero plateau in the
+topological Haldane phase, and experiences abrupt drops at both the phase
+boundaries between the Haldane--large-D and Haldane--N\'eel phases, which
+justifies the usage of genuine multipartite entanglement as a probe of
+topological phases in spin systems.",2106.10690v1
+2021-07-05,Probing primordial black holes with anisotropies in stochastic gravitational-wave background,"Primordial black holes, if considered to constitute a significant fraction of
+cold dark matter, trace the inhomogeneous large-scale structure of the
+Universe. Consequently, the stochastic gravitational-wave background,
+originating from incoherent superposition of unresolved signals emitted by
+primordial black hole binaries, is expected to display anisotropies across the
+sky. In this work, we investigate the angular correlations of such anisotropies
+for the first time and demonstrate their difference from the analogous signal
+produced by astrophysical black hole binaries. We carefully evaluate the
+associated uncertainties due to shot-noise and cosmic variance, and demonstrate
+that the studied signal in the low-frequency regime can be differentiated from
+the signal of astrophysical origin. Our results are particularly promising in
+the stellar mass-range, where the identification of the merger origin has been
+particularly challenging.",2107.01935v3
+2021-07-08,Emergence of Unconventional Interfacial Magnetic Phenomenon in Topological Insulator-Based Magnetic Heterostructures,"In a topological insulator (TI)/magnetic insulator (MI) hetero-structure,
+large spin-orbit coupling of the TI and inversion symmetry breaking at the
+interface could foster non-planar spin textures such as skyrmions at the
+interface. This is observed as topological Hall effect in a conventional Hall
+set-up. While this effect has been observed at the interface of TI/MI, where MI
+beholds perpendicular magnetic anisotropy, non-trivial spin-textures that
+develop in interfacial MI with in-plane magnetic anisotropy is under-reported.
+In this work, we study Bi$_2$Te$_3$/EuS hetero-structure using planar Hall
+effect (PHE). We observe planar topological Hall and spontaneous planar Hall
+features that are characteristic of non-trivial in-plane spin textures at the
+interface. We find that the latter is minimum when the current and magnetic
+field directions are aligned parallel, and maximum when they are aligned
+perpendicularly within the sample plane, which maybe attributed to the
+underlying planar anisotropy of the spin-texture. These results demonstrate the
+importance of PHE for sensitive detection and characterization of non-trivial
+magnetic phase that has evaded exploration in the TI/MI interface.",2107.03596v2
+2021-07-08,Self-consistently renormailzed spin-wave theory of layered ferromagnets on honeycomb lattice,"We develop a self-consistently renormalized spin-wave theory, within a
+mean-field approximation, for the two-dimensional Heisenberg ferromagnet with
+perpendicular easy-axis anisotropy on the honeycomb lattice, as well as its
+few-layer and bulk extensions. In this method, the magnetization dependence on
+temperature is found as the solution of the self-consistency equation.
+Furthermore, we account for the physical difference of surface and bulk layers
+by treating the layers as separate sublattices. Thus, the method can be readily
+generalized to study various magnetic phenomena in a broad range of systems,
+including those comprising magnetically inequivalent sublattices. Using our
+theory, we calculate the temperature-dependent magnetization for two
+chromium-based layered van der Waals insulating magnets, Cr$_2$Ge$_2$Te$_6$ and
+CrI$_3$, employing various sets of Heisenberg exchange and single-ion
+anisotropy values reported for these materials in the existing literature. As
+expected, we observe a strong dimensionality effect where the ordering
+temperature is reduced and its sensitivity on the anisotropy is enhanced with
+the decrease of dimensionality.",2107.04085v1
+2021-07-12,Origin of Perpendicular Magnetic Anisotropy in Yttrium Iron Garnet Thin Films Grown on Si (100),"We report the magnetic properties of yttrium iron garnet (YIG) thin films
+grown by pulsed laser deposition technique. The films were deposited on Si
+(100) substrates in the range of 15-50 nm thickness. Magnetic characterizations
+were investigated by ferromagnetic resonance spectra. Perpendicular magnetic
+easy axis was achieved up to 50 nm thickness. We observed that the
+perpendicular anisotropy values decreased by increasing the film thickness. The
+origin of the perpendicular magnetic anisotropy (PMA) was attributed to the
+texture and the lattice distortion in the YIG thin films. We anticipate that
+perpendicularly magnetized YIG thin films on Si substrates pave the way for a
+cheaper and compatible fabrication process.",2107.05591v1
+2021-07-23,Green's function formalism for nonlocal elliptical magnon transport,"We develop a non-equilibrium Green's function formalism to study magnonic
+spin transport through a strongly anisotropic ferromagnetic insulator contacted
+by metallic leads. We model the ferromagnetic insulator as a finite-sized
+one-dimensional spin chain, with metallic contacts at the first and last sites
+that inject and detect spin in the form of magnons. In the presence of
+anisotropy, these ferromagnetic magnons become elliptically polarized, and spin
+conservation is broken. We show that this gives rise to a novel parasitic spin
+conductance, which becomes dominant at high anisotropy. Moreover, the spin
+state of the ferromagnet becomes squeezed in the high-anisotropy regime. We
+show that the squeezing may be globally reduced by the application of a local
+spin bias.",2107.11072v2
+2021-08-05,Triaxial magnetic anisotropy in the two-dimensional ferromagnetic semiconductor CrSBr,"Two-dimensional (2D) ferromagnets have recently drawn extensive attention,
+and here we study the electronic structure and magnetic properties of the bulk
+and monolayer of CrSBr, using first-principles calculations and Monte Carlo
+simulations. Our results show that bulk CrSBr is a magnetic semiconductor and
+has the easy magnetization b-axis, hard c-axis, and intermediate a-axis. Thus,
+the experimental triaxial magnetic anisotropy (MA) is well reproduced here, and
+it is identified to be the joint effects of spin-orbit coupling (SOC) and
+magnetic dipole-dipole interaction. We find that bulk CrSBr has a strong
+ferromagnetic (FM) intralayer coupling but a marginal interlayer one. We also
+study CrSBr monolayer in detail and find that the intralayer FM exchange
+persists and the shape anisotropy has a more pronounced contribution to the MA.
+Using the parameters of the FM exchange and the triaxial MA, our Monte Carlo
+simulations show that CrSBr monolayer has Curie temperature Tc = 175 K.
+Moreover, we find that a uniaxial tensile (compressive) strain along the a (b)
+axis would further increase the Tc.",2108.02418v2
+2021-08-14,Voltage-controlled magnetism enabled by resistive switching,"The discovery of new mechanisms of controlling magnetic properties by
+electric fields or currents furthers the fundamental understanding of magnetism
+and has important implications for practical use. Here, we present a novel
+approach of utilizing resistive switching to control magnetic anisotropy. We
+study a ferromagnetic oxide that exhibits an electrically triggered
+metal-to-insulator phase transition producing a volatile resistive switching.
+This switching occurs in a characteristic spatial pattern: the formation of a
+transverse insulating barrier inside a metallic matrix resulting in an unusual
+ferromagnetic/paramagnetic/ferromagnetic configuration. We found that the
+formation of this voltage-driven paramagnetic insulating barrier is accompanied
+by the emergence of a strong uniaxial magnetic anisotropy that overpowers the
+intrinsic material anisotropy. Our results demonstrate that resistive switching
+is an effective tool for manipulating magnetic properties. Because resistive
+switching can be induced in a very broad range of materials, our findings could
+enable a new class of voltage-controlled magnetism systems.",2108.06445v1
+2021-09-03,Effective Debye Screening Mass in an Anisotropic Quark Gluon Plasma,"Due to the rapid longitudinal expansion of the quark-gluon plasma created in
+heavy-ion collisions, large local-rest-frame momentum-space anisotropies are
+generated during the system's evolution. These momentum-space anisotropies
+complicate the modeling of heavy-quarkonium dynamics in the quark-gluon plasma
+due to the fact that the resulting inter-quark potentials are spatially
+anisotropic, requiring real-time solution of the 3D Schr\""odinger equation.
+Herein, we introduce a method for reducing anisotropic heavy-quark potentials
+to isotropic ones by introducing an effective screening mass that depends on
+the quantum numbers $l$ and $m$ of a given state. We demonstrate that, using
+the resulting effective Debye screening masses, one can solve a 1D
+Schr\""odinger equation and reproduce the full 3D results for the energies and
+binding energies of low-lying heavy-quarkonium bound states to relatively high
+accuracy. The resulting effective isotropic potential models could provide an
+efficient method for including momentum-anisotropy effects in open quantum
+system simulations of heavy-quarkonium dynamics in the quark-gluon plasma.",2109.01284v2
+2021-09-03,Mechanisms of the in-plane magnetic anisotropy in superconducting NbSe2,"We present a unifying picture of the magnetic in-plane anisotropies of
+two-dimensional superconductors based on transition metal dichalcogenides. The
+symmetry considerations are first applied to constrain the form of the
+conductivity tensor. We hence conclude that the two-fold periodicity of
+transport distinct from the planar Hall related contributions requires a tensor
+perturbation. At the same time, the six-fold periodic variation of the critical
+field results from the Rashba spin-orbit coupling on a hexagonal lattice. We
+have considered the effect of a weak tensor perturbation on the critical field,
+gap function, and magneto-conductivity. The latter is studied using the
+time-dependent Ginzburg-Landau phenomenology. The common origin of the two-fold
+anisotropy in transport and thermodynamics properties is identified. The scheme
+constructed here is applied to describe the existing theoretical scenarios from
+a unified point of view. This allows us to single out the differences and
+similarities between the suggested approaches.",2109.01505v1
+2021-09-12,"Spin excitation spectra in helimagnetic states: proper-screw, cycloid, vortex crystal, and hedgehog lattice","We investigate the spin excitation spectra in chiral and polar magnets by the
+linear spin-wave theory for an effective spin model with symmetric and
+antisymmetric long-range interactions. In one dimension, we obtain the analytic
+form of the dynamical spin structure factor for proper-screw and cycloidal
+helical spin states with uniform twists, which shows a gapless mode with strong
+intensity at the helical wave number. When introducing spin anisotropy in the
+symmetric interactions, we numerically show that the stable spin spirals become
+elliptically anisotropic with nonuniform twists and the spin excitation is
+gapped. In higher dimensions, we find that similar anisotropy stabilizes
+multiple-$Q$ spin states, such as vortex crystals and hedgehog lattices. We
+show that the anisotropy in these states manifests itself in the dynamical spin
+structure factor: a strong intensity in the transverse components to the wave
+number appears only when the helical wave vector and the corresponding easy
+axis are perpendicular to each other. Our findings could be useful not only to
+identify the spin structure but also to deduce the stabilization mechanism by
+inelastic neutron scattering measurements.",2109.05628v2
+2021-09-16,Lone pair driven anisotropy in antimony chalcogenide semiconductors,"Antimony sulfide (Sb2S3) and selenide (Sb2Se3) have emerged as promising
+earth-abundant alternatives among thin-film photovoltaic compounds. A
+distinguishing feature of these materials is their anisotropic crystal
+structures, which are composed of quasi-one-dimensional (1D) [Sb4X6]n ribbons.
+The interaction between ribbons has been reported to be van der Waals (vdW) in
+nature and Sb2X3 are thus commonly classified in the literature as 1D
+semiconductors. However, based on first-principles calculations, here we show
+that inter-ribbon interactions are present in Sb2X3 beyond the vdW regime. The
+origin of the anisotropic structures is related to the stereochemical activity
+of the Sb 5s lone pair according to electronic structure analysis. The impacts
+of structural anisotropy on the electronic and optical properties are further
+examined, including the presence of higher dimensional Fermi surfaces for
+charge carrier transport. Our study provides guidelines for optimising the
+performance of Sb2X3-based solar cells via device structuring based on the
+underlying crystal anisotropy.",2109.08117v3
+2021-09-16,Parameter estimation in an anisotropic expanding spacetime,"In this work, we investigate how the anisotropy affects the cosmological
+parameters estimation. Here the anisotropy is incorporated as a small
+gravitational disturbance. We calculate the Fisher information for both
+cosmological parameters $\epsilon$ (expansion volume) and $\rho$ (expansion
+rate), and we show that the anisotropy introduces oscillations in the Fisher
+information spectrum. This implies that the estimation of the cosmological
+parameters is sensible to the direction of the momentum $k$ of particles. In
+addition, we observe that for small values of the momentum $k$ there is a
+substantial difference between the Fisher information spectrum for the minimum
+and conformal couplings.",2109.08252v1
+2021-09-23,Anisotropy of the proton kinetic energy as a tool for capturing structural transition in nanoconfined H$_2$O,"The proton dynamics of a 2D water monolayer confined inside a graphene slit
+pore is studied in Cartesian and molecular frames of reference using molecular
+dynamics simulations. The vibrational density of states of the proton was
+calculated versus temperature and was further used to deduce the mean kinetic
+energy of the hydrogen atoms, Ke(H), in both frames of reference. The
+directional components of Ke(H) are in good agreement with experimental
+observations for bulk as well as nanoconfined water. Nonetheless, while in the
+molecular frame of reference the effect of temperature on the anisotropy ratios
+of Ke(H) (the ratio between its directional components) are practically
+invariant between the 2D and 3D cases, those in the Cartesian frame of
+reference reveal a rather notable reduction across 200K, indicating the
+occurrence of an order-disorder transition. This result is further supported by
+the calculated entropy and enthalpy of the confined water molecules. Overall it
+is shown that Ke(H) anisotropy ratios may serve as a valuable order parameter
+for detecting structural transformations in hydrogen bonds containing molecular
+systems.",2109.11175v1
+2021-09-27,Subdiffusive hydrodynamics of nearly-integrable anisotropic spin chains,"We address spin transport in the easy-axis Heisenberg spin chain subject to
+integrability-breaking perturbations. We find that spin transport is
+subdiffusive with dynamical exponent $z=4$ up to a timescale that is
+parametrically long in the anisotropy. In the limit of infinite anisotropy,
+transport is subdiffusive at all times; for large finite anisotropy, one
+eventually recovers diffusion at late times, but with a diffusion constant
+independent of the strength of the integrability breaking perturbation. We
+provide numerical evidence for these findings, and explain them by adapting the
+generalized hydrodynamics framework to nearly integrable dynamics. Our results
+show that the diffusion constant of near-integrable interacting spin chains is
+generically not perturbative in the integrability breaking strength.",2109.13251v2
+2021-10-06,Nano-imaging of the edge-dependent optical polarization anisotropy of black phosphorus,"The electronic structure and functionality of 2D materials is highly
+sensitive to structural morphology, opening the possibility for manipulating
+material properties, but also making predictable and reproducible functionality
+challenging. Black phosphorus (BP), a corrugated orthorhombic 2D material, has
+in-plane optical absorption anisotropy critical for applications such as
+directional photonics, plasmonics, and waveguides. Here, we use
+polarization-dependent photoemission electron microscopy to visualize the
+anisotropic optical absorption of BP with 54 nm spatial resolution. We find the
+edges of BP flakes have a shift in their optical polarization anisotropy from
+the flake interior due to the 1D confinement and symmetry reduction at flake
+edges that alter the electronic charge distributions and transition dipole
+moments of edge electronic states, confirmed with first-principles
+calculations. These results uncover previously hidden modification of the
+polarization-dependent absorbance at the edges of BP, highlighting the
+opportunity for selective excitation of edge states of 2D materials with
+polarized light.",2110.02430v3
+2021-10-17,Semiclassical Boltzmann magnetotransport theory in anisotropic systems with a nonvanishing Berry curvature,"Understanding the transport behavior of an electronic system under the
+influence of a magnetic field remains a key subject in condensed matter
+physics. Particularly in topological materials, their nonvanishing Berry
+curvature can lead to many interesting phenomena in magnetotransport owing to
+the coupling between the magnetic field and Berry curvature. By fully
+incorporating both the field-driven anisotropy and inherent anisotropy in the
+band dispersion, we study the semiclassical Boltzmann magnetotransport theory
+in topological materials with a nonvanishing Berry curvature. We show that as a
+solution to the Boltzmann transport equation the effective mean-free-path
+vector is given by the integral equation, including the effective velocity
+arising from the coupling between the magnetic field, Berry curvature and
+mobility. We also calculate the conductivity of Weyl semimetals with an
+isotropic energy dispersion, and find that the coupling between the magnetic
+field and Berry curvature induces anisotropy in the relaxation time, showing a
+substantial deviation from the result obtained assuming a constant relaxation
+time.",2110.08816v3
+2021-10-31,Thermally induced all-optical ferromagnetic resonance in thin YIG films,"All-optical ferromagnetic resonance (AO-FMR) is a powerful tool for local
+detection of micromagnetic parameters, such as magnetic anisotropy, Gilbert
+damping or spin stiffness. In this work we demonstrate that the AO-FMR method
+can be used in thin films of Yttrium Iron Garnet (YIG) if a metallic capping
+layer (Au, Pt) is deposited on top of the film. Magnetization precession is
+triggered by heating of the metallic layer with femtosecond laser pulses. The
+heating modifies the magneto-crystalline anisotropy of the YIG film and shifts
+the quasi-equilibrium orientation of magnetization, which results in
+precessional magnetization dynamics. The laser-induced magnetization precession
+corresponds to a uniform (Kittel) magnon mode, with the precession frequency
+determined by the magnetic anisotropy of the material as well as the external
+magnetic field, and the damping time set by a Gilbert damping parameter. The
+AO-FMR method thus enables measuring local magnetic properties, with spatial
+resolution given only by the laser spot size.",2111.00586v1
+2021-11-02,Interferometric weak value of polarization observable and differential Jones matrix algebra,"The quantification of simultaneously present weak polarization anisotropy
+effects are of practical interest from polarimetric and metrological
+perspective. Recently, in Phys. Rev. A 103, 053518, we experimentally
+demonstrated a classical analog of post-selected quantum weak measurement
+through optical interferometry to amplify all possible weak polarization
+anisotropy effects individually. Here, we propose an extension of this
+interferometric framework to quantify simultaneously present polarization
+anisotropy effects. Moreover, a clear correspondence of differential Jones
+matrix approach with the present scheme is indicated. The proposed scheme
+enables the measurement of differential Jones matrices through characteristic
+Stokes vector elements. Our proposal leads to a new class of polarimeter for
+experimental detection of differential Jones matrix of non-depolarizing
+anisotropic medium exhibiting simultaneous multiple polarimetric effects of
+tiny magnitude.",2111.01642v2
+2021-11-16,Synthesis and thermal expansion of chalcogenide MAX phase Hf2SeC,"Thermal expansion of MAX phases along different directions tended to be
+different because of the anisotropy of hexagonal crystals. Herein, a new Hf2SeC
+phase was synthesized and confirmed to be relatively isotropic, whose
+coefficients of thermal expansion (CTEs) were determined to be 9.73 {\mu}K-1
+and 10.18 {\mu}K-1 along a and c directions. The strong M-S bond endowed Hf2SC
+and Zr2SC lower CTEs than Hf2SeC and Zr2SeC. A good relationship between the
+thermal expansion anisotropy and the ratio of elastic stiffness constant c11
+and c33 was established. This straightforward approximation could be used to
+roughly predict the thermal expansion anisotropy of MAX phases.",2111.08257v1
+2021-11-21,Electrophoresis of metal-dielectric Janus particles with dipolar director symmetry in nematic liquid crystals,"We study electrophoretic mobility of metal-dielectric Janus particles with
+dipolar director profile in two nematic liquid crystals (LCs) having same
+(positive) conductivity anisotropy and opposite dielectric anisotropy. The
+applied ac electric field is parallel and perpendicular to the director for the
+positive and negative dielectric anisotropy LCs, respectively. The velocity of
+the Janus particles in both LCs is significantly higher than that of the
+non-Janus particles. We map the electroosmotic flow fields surrounding the
+particles using microparticle image velocimetry ($\mu$-PIV) and show that the
+flows on the metal hemisphere is stronger than that on the dielectric
+hemisphere and the pumping of LC along the direction of motion of the Janus
+particles is more than that of the non-Janus particles. For a given liquid
+crystal, particles with asymmetric surface properties is useful for enhancing
+their electrophoretic mobility and activity.",2111.10714v2
+2021-11-26,Characterization of Anisotropic Gaussian Random Fields by Minkowski Tensors,"Gaussian random fields are among the most important models of amorphous
+spatial structures and appear across length scales in a variety of physical,
+biological, and geological applications, from composite materials to geospatial
+data. Anisotropy in such systems can sensitively and comprehensively be
+characterized by the so-called Minkowski tensors from integral geometry. Here,
+we analytically calculate the expected Minkowski tensors of arbitrary rank for
+the level sets of Gaussian random fields. The explicit expressions for
+interfacial Minkowski tensors are confirmed in detailed simulations. We
+demonstrate how the Minkowski tensors detect and characterize the anisotropy of
+the level sets, and we clarify which shape information is contained in the
+Minkowski tensors of different rank. Using an irreducible representation of the
+Minkowski tensors in the Euclidean plane, we show that higher-rank tensors
+indeed contain additional anisotropy information compared to a rank two tensor.
+Surprisingly, we can nevertheless predict this information from the second-rank
+tensor if we assume that the random field is Gaussian. This relation between
+tensors of different rank is independent of the details of the model. It is,
+therefore, useful for a null hypothesis test that detects non-Gaussianities in
+anisotropic random fields.",2111.13349v1
+2021-11-30,Dimension reduction induced anisotropic magnetic thermal conductivity in hematite nanowire,"The thermophysical properties near the magnetic phase transition point is of
+great importance in the study of critical phenomenon. Low-dimensional materials
+are suggested to hold different thermophysical properties comparing to their
+bulk counterpart due to the dimension induced quantum confinement and
+anisotropy. In this work, we measured the thermal conductivity of
+$\alpha$-Fe$_2$O$_3$ nanowires along [110] direction (growing direction) with
+temperature from 100K to 150K and found a dip of thermal conductivity near the
+Morin temperature. We found the thermal conductivity near Morin temperature
+varies with the angle between magnetic field and [110] direction of nanowire.
+More specifically, an angular-dependent thermal conductivity is observed, due
+to the magnetic field induced movement of magnetic domain wall. The angle
+corresponding to the maximum of thermal conductivity varies near the Morin
+transition temperature, due to the different magnetic easy axis as suggested by
+our calculation based on magnetic anisotropy energy. This angular dependence of
+thermal conductivity indicates that the easy axis of $\alpha$-Fe$_2$O$_3$
+nanowires is different from bulk $\alpha$-Fe$_2$O$_3$ due to the geometric
+anisotropy.",2111.15137v1
+2021-12-02,Strain Engineering of Magnetic Anisotropy in Epitaxial Films of Cobalt Ferrite,"Perpendicular magnetic anisotropy (PMA) energy up to
+$K_{\mathrm{u}}=6.1\pm0.8$ MJ m$^{-3}$ is demonstrated in this study by
+inducing large lattice-distortion exceeding 3% at room temperature in
+epitaxially distorted cobalt ferrite Co$ _{x} $Fe$ _{3-x} $O$ _{4} $ (x = 0.72)
+(001) thin films. Although the thin film materials include no rare-earth
+elements or noble metals, the observed $ K_{u} $ is larger than that of the
+neodymium-iron-boron compounds for high-performance permanent magnets. The
+large PMA is attributed to the significantly enhanced magneto-elastic effects,
+which are pronounced in distorted films with epitaxial lattice structures upon
+introducing a distortion control layer of composition Mg$ _{2-x} $Sn$_{1+x}$O$
+_{4} $. Surprisingly, the induced $ K_{u} $ can be quantitatively explained in
+terms of the agreement between the local crystal field of Co$ ^{2+} $ and the
+phenomenological magneto-elastic model, indicating that the linear response of
+induced $K_u$ is sufficiently valid even under lattice distortions as large as
+3.2%. Controlling tetragonal lattice deformation using a non-magnetic spinel
+layer for ferrites could be a promising protocol for developing materials with
+large magnetic anisotropies.",2112.00916v1
+2021-12-03,Inertial range magnetic fluctuation anisotropy observed from PSP first seven orbits,"Solar wind turbulence is anisotropic with respect to the mean magnetic field.
+Anisotropy leads to ambiguity when interpreting in-situ turbulence observations
+in the solar wind because an apparent change in the measurements could be due
+either to the change of intrinsic turbulence properties or to a simple change
+of the spacecraft sampling direction. We demonstrate the ambiguity using the
+spectral index and magnetic compressibility in the inertial range observed by
+the Parker Solar Probe during its first seven orbits ranging from 0.1 to 0.6
+AU. To unravel the effects of the sampling direction, we assess whether the
+wavevector anisotropy is consistent with a two-dimensional (2D) plus slab
+turbulence transport model and determine the fraction of power in the 2D versus
+slab component. Our results confirm that the 2D plus slab model is consistent
+with the data and the power ratio between 2D and slab components depends on
+radial distance, with the relative power in 2D fluctuations becoming smaller
+closer to the Sun.",2112.01711v1
+2021-12-08,Interplay of orientational order and roughness in simulated thin film growth of anisotropically interacting particles,"Roughness and orientational order in thin films of anisotropic particles are
+investigated using kinetic Monte Carlo simulations on a cubic lattice.
+Anisotropic next-neighbor interactions between the lattice particles were
+chosen to mimic the effects of shape anisotropy in the interactions of disc- or
+rod-like molecules with van-der-Waals attractions. Increasing anisotropy leads
+first to a preferred orientation in the film (which is close to the
+corresponding equilibrium transition) while the qualitative mode of roughness
+evolution (known from isotropic systems) does not change. At strong
+anisotropies, an effective step-edge (Ehrlich-Schwoebel) barrier appears and a
+non-equilibrium roughening effect is found, accompanied by re-ordering in the
+film which can be interpreted as the nucleation and growth of domains of
+lying-down discs or rods. The information on order and roughness is combined
+into a diagram of dynamic growth modes.",2112.04270v3
+2021-12-09,Exchange-bias dependent diffusion rate of hydrogen discovered from evolution of hydrogen-induced noncollinear magnetic anisotropy in FePd thin films,"Hydrogenation-induced noncollinear magnetic anisotropy is observed from the
+evolution of the magnetic domains in FePd alloy thin films using magneto-optic
+Kerr effect (MOKE) microscopy. MOKE images reveal complicated competitions
+between different magnetic anisotropies during hydrogen diffusion into the
+film. An intriguing enhancement of the hydrogen diffusion rate due to the
+presence of an initial exchange bias induced by a high magnet field is thereby
+discovered, pointing to an additional scope of controllability of magnetic
+metal hydrides as potential future hydrogen sensing and storage materials.",2112.05079v1
+2021-12-09,Spectral Distortion Anisotropy from Inflation for Primordial Black Holes,"Single field inflationary models that seek to greatly enhance small scale
+power in order to form primordial black holes predict both a squeezed
+bispectrum that is enhanced by this small scale power and a potentially
+detectable enhancement of CMB spectral distortions. Despite this combination,
+spectral distortion anisotropy on CMB scales remains small since the squeezed
+bispectrum represents an unobservable modulation of the scale rather than local
+amplitude for the short wavelength acoustic power that dissipates and forms the
+$\mu$ spectral distortion. The leading order amplitude effect comes from the
+local modulation of acoustic dissipation at the beginning of the $\mu$ epoch at
+the end of thermalization by a long wavelength mode that is correlated with CMB
+anisotropy itself. Compensating factors from the suppression by the square of
+the ratio the comoving horizon at thermalization to the smallest detectable
+primary CMB scales ($\sim 0.0005$) and maximal allowed enhancement of $\mu$
+($\sim 5000$) leaves a signal in the $\mu T$ cross spectrum that is still well
+beyond the capabilities of PIXIE or LiteBIRD due to sensitivity and resolution
+while remaining much larger than in single field slow roll inflation and
+potentially observable.",2112.05190v1
+2021-12-09,Electronic control and switching of entangled spin state using anisotropy and exchange in the three-particle paradigm,"We explore the control and switching of the entangled spin states of
+multi-spin particle qubit coupled to an electron using a three-particle spin
+model described by $S_i$ ($i=1,2,3$), in which $S_1=\tfrac{1}{2}$ is an
+electron and $S_{2,3}$ can have any spin with both exchange coupling and
+magnetic anisotropy. We derive a general formula for the existence of a
+switching (DJ) resonance for any spin $S_{2,3}$. We further contrast the
+entanglement switching mechanisms for the $S_{2,3}=\tfrac{1}{2}$ and
+$S_{2,3}=1$ spin models. We find that while the onsite magnetic anisotropy in
+the case of $S_{2,3}>\tfrac{1}{2}$ allows full control of their spin states via
+interaction with $S_1$, in order to achieve acceptable control of a Bloch
+vector within the $S_{2,3}=\tfrac{1}{2}$ model, additional mechanisms, such as
+anisotropic exchange coupling, are required.",2112.05223v2
+2021-12-14,Robust perpendicular magnetic anisotropy in Ce substituted yttrium iron garnet epitaxial thin films,"Cerium substituted yttrium iron garnet (Ce:YIG) epitaxial thin films are
+prepared on gadolinium gallium garnet (GGG) substrate with pulsed laser
+deposition (PLD). It is observed that the films grown on GGG(111) substrate
+exhibit perpendicular magnetic anisotropy (PMA) as compared to films grown on
+GGG(100) substrate. The developed PMA is confirmed from magneto-optical Kerr
+effect, bulk magnetization and ferromagnetic resonance measurements. Further,
+the magnetic bubble domains are observed in the films exhibiting PMA. The
+observations are explained in terms of the growth direction of Ce:YIG films and
+the interplay of various magnetic anisotropy terms. The observed PMA is found
+to be tunable with thickness of the film and a remarkable temperature stability
+of the PMA is observed in all the studied films of Ce:YIG deposited on GGG(111)
+substrate.",2112.07264v1
+2021-12-19,A New Picture of Cosmic String Evolution and Anisotropic Stochastic Gravitational-Wave Background,"We investigate the anisotropies of the stochastic gravitational-wave
+background (SGWB) produced by cosmic strings associated with the spontaneous
+U(1) symmetry breaking of Grand Unified Theory, which happens at the onset of
+inflation. The string network evolution is determined by primordial
+fluctuations and never reaches the scaling regime. The string loops are
+inhomogeneously distributed in large scale regions, resulting in large
+anisotropies in the SGWB. We find that the angular power spectrum of SGWB
+anisotropies depends on frequency, which is testable in multiband observations
+of GWs. In particular, GWs from the cosmic strings can appropriately interpret
+the common-spectrum process reported by NANOGrav collaboration, and the angular
+power spectrum in the nanohertz band,
+$\mathtt{l}(\mathtt{l}+1)C_{\mathtt{l}}=5.6\times 10^{-2}$ at large scales, is
+expected to be detectable by pulsar timing array experiments in the near
+future.",2112.10131v1
+2021-12-23,Visible Out-of-plane Polarized Luminescence and Electronic Resonance from Black Phosphorus,"Black Phosphorus (BP) is unique among layered materials owing to its
+homonuclear lattice and strong structural anisotropy. While recent
+investigations on few layers BP have extensively explored the in-plane (a,c)
+anisotropy, much less attention has been given to the out-of-plane direction
+(b). Here, the optical response from bulk BP is probed using
+polarization-resolved photoluminescence (PL), photoluminescence excitation
+(PLE) and resonant Raman scattering along the zigzag, out-of-plane, and
+armchair directions. PL reveals an unexpected b-polarized emission occurring in
+the visible at 1.75 eV, far above the fundamental gap (0.3 eV). PLE indicates
+that this emission is generated through b-polarized excitation at 2.3 eV. The
+same electronic resonance is observed in resonant Raman scans, where the
+scattering efficiency of both Ag phonon modes is enhanced. These experimental
+results are fully consistent with DFT calculations of the permittivity tensor
+elements and demonstrate the remarkable extent to which the anisotropy
+influences the optical properties and carrier dynamics in black phosphorus.",2112.12617v1
+2021-12-28,$Λ$CDM cosmology with a quiescent anisotropy in a higher dimensional steady state universe,"In this work, which follows a series of studies on the higher-dimensional
+steady state universe idea and prepared for Professor Tekin Dereli's
+Festschrift, we show the influence of the dynamical internal (unobservable)
+space on the evolution of the possible anisotropy of the external (observable)
+space. We obtain mathematically exactly the same Friedmann equation of the
+standard $\Lambda$CDM model for the external space, but with some remarkable
+physical differences. In particular, the higher-dimensional negative
+cosmological constant plays the role of the four-dimensional positive
+cosmological constant and the expansion anisotropy, viz., the shear scalar, of
+the external space mimics a negative cosmological constant; it would mimic a
+stiff fluid when allowed on top of the standard $\Lambda$CDM model. This latter
+feature gives us the opportunity to manipulate the CMB quadrupole temperature
+fluctuation, suggesting a possible answer to the fact that its observed value
+is lower than that predicted by the standard $\Lambda$CDM model.",2112.14259v1
+2021-12-29,A unified theory of ferromagnetic quantum phase transitions in heavy fermion metals,"Motivated by the recent discovery of a continuous ferromagnetic quantum phase
+transition in CeRh$_6$Ge$_4$ and its distinction from other U-based heavy
+fermion metals such as UGe$_2$, we develop a unified explanation of their
+different ground state properties based on an anisotropic ferromagnetic
+Kondo-Heisenberg model. We employ an improved large-$N$ Schwinger boson
+approach and predict a full phase diagram containing both a continuous
+ferromagnetic quantum phase transition for large magnetic anisotropy and
+first-order transitions for relatively small anisotropy. Our calculations
+reveal three different ferromagnetic phases including a half-metallic spin
+selective Kondo insulator with a constant magnetization. The Fermi surface
+topologies are found to change abruptly between different phases, consistent
+with that observed in UGe$_2$. At finite temperatures, we predict the
+development of Kondo hybridization well above the ferromagnetic long-range
+order and its relocalization near the phase transition, in good agreement with
+band measurements in CeRh$_6$Ge$_4$. Our results highlight the importance of
+magnetic anisotropy and provide a unified theory for understanding the
+ferromagnetic quantum phase transitions in heavy fermion metals.",2112.14515v1
+2021-12-30,ARGO-YBJ Observation of the Large-scale Anisotropy During the Solar Minimum between Cycles 23 and 24,"This paper reports on the measurement of the large-scale anisotropy in the
+distribution of cosmic-ray arrival directions using the data collected by the
+air shower detector ARGO-YBJ from 2008 January to 2009 December,during the
+minimum of solar activity between cycles 23 and 24. In this period, more than
+200 billion showers were recorded with energies between 1 and 30 TeV. The
+observed two-dimensional distribution of cosmic rays is characterized by two
+wide regions of excess and deficit, respectively, both of relative intensity
+0.001 with respect to a uniform flux, superimposed on smaller size structures.
+The harmonic analysis shows that the large-scale cosmic-ray relative intensity
+as a function of R.A. can be described by the first and second terms of a
+Fouries series. The high event statistics allow the study of the energy
+dependence of the anistropy, showing that the amplitude increases with energy,
+with a maximum intensity at 10 TeV, and then decreases while the phase slowly
+shifts toward lower values of R.A. with increasing energy. The ARGO-YBJ data
+provide accurate observations over more than a decade of energy around this
+feature of the anisotropy spectrum.",2112.14891v1
+2021-12-31,Random Anisotropy Magnet at Finite Temperature,"Abstract We present finite-temperature Monte Carlo studies of a 2D
+random-anisotropy magnet on lattices containing one million spins. The
+correlated spin-glass state predicted by analytical theories is reproduced in
+simulations, as are the field-cooled and zero-field-cooled magnetization curves
+observed in experiments. The orientations of lattice spins begin to freeze when
+the temperature is lowered. The freezing transition is due to the energy
+barriers generated by the random anisotropy rather than due to random
+interactions in conventional spin-glasses. We describe freezing by introducing
+the time-dependent spin-glass order parameter $q$ and the spin-melting time
+$\tau_{M}$ defined via $q=\tau_{M}/t$ above freezing, where t is the time of
+the experiment represented by the number of Monte Carlo steps.",2112.15269v1
+2022-01-02,Percolation on spatial anisotropic networks,"Many realistic systems such as infrastructures are characterized by spatial
+structure and anisotropic alignment. Here we propose and study a model for
+dealing with such characteristics by introducing a parameter that controls the
+strength of the anisotropy in the spatial network. This parameter is added to
+an existing isotropic model used to describe networks under spatial
+constraints, thus generalizing the spatial model to take into account both
+spatial and anisotropic features. We study the resilience of such networks by
+using a percolation process and find that anisotropy has a negative impact on a
+network's robustness. In addition, our results suggest that the anisotropy in
+this model does not affect the critical exponent of the correlation length,
+$\nu$, which remains the same as the known $\nu$ in 2D isotropic lattices.",2201.00373v1
+2021-12-29,Modifications of CMB spectrum by nonextensive statistical mechanics,"Cosmic microwave background radiation can supply us some most significant
+parts of the information on the universe. Some researchers believe that The
+gravitational system cannot be decribed by the standard statistical mechanics.
+In this article we apply Tsallis nonextensive statistical mechanics to
+investigate CMB spectrum and related cosmological processes. Based on recent
+observational data we find that the nonextensive statistical mechanics can
+modify the values of related physical quantites. Since the value of physical
+quantites have changed, some processes, such as recombination, can be affected.
+We have investigated the anisotropy of the CMB for two effects: the dipole
+anisotropy of CMB and the Sunyaev-Zel'dovich effect. We find that the dipole
+anisotropy of CMB cannot be modified by the nonextensive statistical mechanics.
+However, the standard result of the Sunyaev-Zel'dovich effect should be
+modified by nonextensive statistical mechanics. In principle, future work can
+distinguish these effects.",2201.00758v1
+2022-01-04,Benchmarking of different strategies to include anisotropy in a curvature-driven multi-phase-field model,"Two benchmark problems for quantitative assessment of anisotropic curvature
+driving force in phase field method were developed and introduced. Both
+benchmarks contained an anisotropically shrinking grain in homogeneous matrix.
+The first benchmark was a shrinking Wulff shape and in the second, such
+inclination dependence of the kinetic coefficient was added so that the
+shrinkage was isotropic. In both cases the match to the expected shape was
+quantified by means of Hausdorff distance and the shrinkage rate was
+analytically expressed. Three different ways of interface energy anisotropy
+inclusion in a multi-phase field model were compared. Because their performance
+was comparable, they were tested in an additional benchmark problem, which
+concerned direct measurement of equilibrium triple junction angles. Based on
+this benchmark, only one of the three strategies to include anisotropy was
+reliable in strongly anisotropic systems.",2201.00922v2
+2022-01-10,"Elastic anisotropy of 1,3,5-Triamino-2,4,6-Trinitrobenzene as a function of temperature and pressure: A Molecular Dynamics study","The equation of state of the triclinic compound
+1,3,5-triamino-2,4,6-trinitrobenzene (TATB) as well as its second-order
+isothermal elastic tensor were computed through classical molecular dynamics
+simulations under various temperature and pressure conditions. Hydrostatic
+pressures similar to previous diamond anvil cell experiments were imposed
+within the range [0, 66] GPa and temperatures chosen between 100 and 900 K in
+conjunction with the most recent version of an all-atom fully-flexible molecule
+force field. The isothermal elastic constants were computed using the
+generalized Hooke's law by fitting Cauchy stress vs. linear strain curves.
+Along isobaric pathways, TATB single crystal stiffness is found to undergo
+linear softening, less pronounced at high pressure, while maintaining its
+elastic anisotropy. On the other hand, along an isothermal pathways, a
+non-linear increase is observed in the elastic constants with a significant
+decrease in anisotropy. Towards a precise mesoscopic modeling of TATB single
+crystal mechanical behavior, we provide ""ready to plug-in"" analytical
+formulations of the P,V,T equation of state and pressure-temperature dependent
+non-linear elasticity.",2201.03224v1
+2022-01-24,Hund's coupling and electronic anisotropy in the spin-density wave state of iron pnictides,"In the multiband systems, Hund's coupling ($J$) plays a significant role in
+the spin and charge excitations. We study the dependence of electronic
+anisotropy on $J$ in terms of Drude-weight along different directions as well
+as the orbital order in the four-fold symmetry broken spin-density wave state
+of iron pnictides. A robust behavior of the Drude-weight anisotropy within a
+small window around $J \sim 0.25U$ with $U$ as intraorbital Coulomb interaction
+is described in terms of orbital-weight distribution along the reconstructed
+Fermi surfaces. We also find that the ferro-orbital order increases with $J$ in
+the widely accepted regime for the latter, which is explained as a consequence
+of rising exchange field with an increase in magnetization.",2201.09808v1
+2022-01-26,Magnetoconductance Anisotropies and Aharonov-Casher Phases,"The spin-orbit interaction is a key tool for manipulating and functionalizing
+spin-dependent electron transport. However, the precise value of the spin-orbit
+coupling constant is hard to determine and control. Here we propose a
+measurement of the geometric (Aharonov-Casher) phase of the electron
+wavefunction generated by the spin-orbit coupling as a means to deduce the
+spin-orbit coupling strength in weak links. Unlike other proposed measurements
+of geometric phases, which rely on interference, we show that the anisotropy of
+the magnetoconductance, measured at different directions of an external
+magnetic field,is determined by the geometric phase. Specifically we consider
+weak links in which the Rashba interaction is caused by an external electric
+field, but our method is expected to apply also for other forms of the
+spin-orbit coupling. Measuring this magnetoconductance anisotropy thus allows
+calibrating Rashba spintronic devices by an external electric field that tunes
+the spin-orbit interaction.",2201.10845v2
+2022-02-02,Photochemical Anisotropy and Direction-dependent Optical Absorption in Semiconductors,"Photochemical reactions on semiconductors are anisotropic, since they occur
+with different rates on surfaces of different orientation. Understanding the
+origin of this anisotropy is crucial to engineering more efficient
+photocatalysts. In this work, we use hybrid density functional theory (DFT) to
+identify the surfaces associated with the largest number of photo-generated
+carriers in different semiconductors. For each material we create a spherical
+heat map of the probability of optical transitions at different wave vectors.
+These maps allow to identify the directions associated with the majority of the
+photo-generated carriers and can thus be used to make predictions about the
+most reactive surfaces for photochemical applications. Results indicate that it
+is generally possible to correlate the heat maps with the anisotropy of the
+bands observed in conventional band-structure plots, as previously suggested.
+However, we also demonstrate that conventional bands-structure plots do not
+always provide all the informations and that taking into account the
+contribution of all possible transitions weighted by their transition dipole
+moments is crucial to obtain a complete picture.",2202.01073v1
+2022-02-02,Antiferromagnetic parametric resonance driven by voltage-controlled magnetic anisotropy,"Voltage controlled magnetic anisotropy (VCMA) is a low-energy alternative to
+manipulate the ferromagnetic state, which has been recently considered also in
+antiferromagnets (AFMs). Here, we theoretically demonstrate that VCMA can be
+used to excite linear and parametric resonant modes in easy-axis AFMs with
+perpendicular anisotropy, thus opening the way for an efficient electrical
+control of the Neel vector, and for detection of high-frequency dynamics. Our
+work leads to two key results: (i) VCMA parametric pumping experiences the
+so-called exchange enhancement of the coupling efficiency and, thus, is 1-2
+orders of magnitude more efficient than microwave magnetic fields or
+spin-orbit-torques, and (ii) it also allows for zero-field parametric
+resonance, which cannot be achieved by other parametric pumping mechanisms in
+AFMs with out-of-plane easy axis. Therefore, we demonstrate that the VCMA
+parametric pumping is the most promising method for coherent excitation and
+manipulation of AFM order in perpendicular easy-axis AFMs.",2202.01156v1
+2022-02-24,Resistivity anisotropy from the multiorbital Boltzmann equation in nematic FeSe,"We compute the resistivity anisotropy in the nematic phase of FeSe from the
+static solution of the multiorbital Boltzmann equation. By introducing disorder
+at the level of the microscopic multiorbital model we show that even elastic
+scattering by localized impurities may lead to non-trivial anisotropic
+renormalization of the electronic velocities, challenging the usual
+understanding of transport based only on cold- and hot-spots effects. Our model
+takes into account both the $xz/yz$ and the recently proposed $xy$ nematic
+ordering. We show that the latter one has a crucial role in order to reproduce
+the experimentally-measured anisotropy, providing a direct fingerprint of the
+different nematic scenarios on the bulk transport property of FeSe.",2202.12070v2
+2022-03-08,Topological phase transition in magnon bands in a honeycomb ferromagnet driven by sublattice symmetry breaking,"Ferromagnetic honeycomb systems are known to exhibit a magnonic topological
+phase under the existence of the next-nearest neighbor Dzyaloshinskii-Moriya
+interaction (DMI). Motivated by the recent progress in the sublattice-specific
+control of magnetic anisotropy, we study the topological phase of magnon bands
+of honeycomb ferromagnetic monolayer and bilayer with the sublattice symmetry
+breaking due to the different anisotropy energy in the presence of the DMI. We
+show that there is a topological phase transition between the topological
+magnon insulator and the topologically trivial magnon phase driven by the
+change of the relative size of the DMI and the anisotropy differences between
+the sublattices. The magnon thermal Hall conductivity is proposed as an
+experimental probe of the magnon topology.",2203.03845v1
+2022-03-15,Standing spin wave excitation in Bi:YIG films via temperature induced anisotropy changes and magnetoacoustic coupling,"Based on micromagnetic simulations and experimental observations of the
+magnetization and lattice dynamics following the direct optical excitation of
+the magnetic insulator Bi:YIG or indirect excitation via an optically opaque
+Pt/Cu double layer, we disentangle the dynamical effects of magnetic anisotropy
+and magnetoelastic coupling. The strain and temperature of the lattice are
+quantified via modeling ultrafast x-ray diffraction data. Measurements of the
+time-resolved magneto-optical Kerr effect agree well with the magnetization
+dynamics simulated according to the excitation via two mechanisms: The
+magneto-acoustic coupling to the experimentally verified strain dynamics and
+the ultrafast temperature-induced transient change in the magnetic anisotropy.
+The numerical modeling proves that for direct excitation both mechanisms drive
+the fundamental mode with opposite phase. The relative ratio of standing
+spin-wave amplitudes of higher order modes indicates that both mechanisms are
+substantially active.",2203.07851v1
+2022-03-16,Testing the empirical relationship between Forbush decreases and cosmic ray diurnal anisotropy,"The abrupt aperiodic modulation of cosmic ray (CR) flux intensity, often
+referred to as Forbush decrease (FD), plays a significant role in our
+understanding of the Sun-Earth electrodynamics. Accurate and precise
+determination of FD magnitude and timing are among the intractable problems in
+FD-based analysis. FD identification is complicated by CR diurnal anisotropy.
+CR anisotropy can increase or reduce the number and amplitude of FDs. It is
+therefore important to remove its contributions from CR raw data before FD
+identification. Recently, an attempt was made, using a combination of Fourier
+transformed technique and FD-location machine to address this. Thus, two FD
+catalogs and amplitude diurnal variation (ADV) were calculated from filtered
+(FD1 and ADV) and raw (FD2) CR data. In the current work, we test the empirical
+relationship between FD1, FD2, ADV, and solar-geophysical characteristics. Our
+analysis shows that two types of magnetic fields-interplanetary (IMF) and
+geomagnetic (Dst) govern the evolution of CR flux intensity reductions.",2203.08883v1
+2022-03-18,Implications of phonon anisotropy on thermal conductivity of fluorite oxides,"Fluorite oxides are attractive ionic compounds for a range of applications
+with critical thermal management requirements. In view of recent reports
+alluding to anisotropic thermal conductivity in this face-centered cubic
+crystalline systems, we perform a detailed analysis of the impact of
+direction-dependent phonon group velocities and lifetimes on the thermal
+transport of fluorite oxides. We demonstrate that the bulk thermal conductivity
+of this class of materials remains isotropic despite notable anisotropy in
+phonon lifetime and group velocity. However, breaking the symmetry of the
+phonon lifetime under external stimuli including boundary scattering present in
+nonequilibrium molecular dynamics simulations of finite size simulation cell
+gives rise to apparent thermal conductivity anisotropy. We observe that for
+accurate determination of thermal conductivity, it is important to consider
+phonon properties not only along high symmetry directions commonly measured in
+inelastic neutron or x-ray scattering experiments but also of those along lower
+symmetry. Our results suggests that certain low symmetry directions have a
+larger contribution to thermal conductivity compared to high symmetry ones.",2203.09923v2
+2022-03-29,Continuous ferromagnetic quantum phase transition on an anisotropic Kondo lattice,"Motivated by the recent discovery of ferromagnetic quantum criticality in the
+heavy fermion compound CeRh$_6$Ge$_4$, we develop a numerical algorithm of
+infinite projected entangled pair states for the anisotropic ferromagnetic
+Kondo-Heisenberg model in two dimensions and study the ferromagnetic quantum
+phase transitions with varying magnetic and hopping anisotropy. Our
+calculations reveal a continuous ferromagnetic quantum phase transition in the
+large anisotropic region and first-order quantum phase transitions for smaller
+anisotropy. Our results highlight the importance of magnetic anisotropy on
+ferromagnetic quantum criticality in Kondo lattice systems and provide a
+possible explanation for the experimental observation in CeRh$_6$Ge$_4$ with a
+quasi-one-dimensional magnetic structure. Our work opens the avenue for future
+studies of the rich Kondo lattice physics using state-of-the-art tensor network
+approaches.",2203.15475v2
+2022-03-30,Origin of Perpendicular Magnetic Anisotropy in Co$_x$Fe$_{3-x}$O$_{4+δ}$ Thin Films Studied by X-ray Magnetic Circular and Linear Dichroisms,"We investigate the element-specific spin and orbital states and their roles
+on magnetic anisotropy in the Co-ferrite (Co$_x$Fe$_{3-x}$O$_{4+\delta}$ (001))
+thin films which exhibit perpendicular magnetic anisotropy (PMA). The origin of
+PMA in the low $x$ region ($x$ $<$ 1) can be mainly explained by the large
+perpendicular orbital magnetic moments in the Co$^{2+}$ (3$d^7$) states
+detected by X-ray magnetic circular and linear dichroisms (XMCD/XMLD). The XMLD
+for a PMA film ($x=0.2$) with square hysteresis curve shows the oblate charge
+distribution in the Co$^{2+}$ site, which is consistent with the change in
+local nearest neighbor distance in Co detected by extended X-ray absorption
+fine structure analysis. Our finding reveals that the microscopic origin of PMA
+in Co-ferrite comes from the enhanced orbital magnetic moments along
+out-of-plane [001] direction through in-plane charge distribution by tensile
+strain, which adds the material functionalities in spinel ferrite thin films
+from the viewpoint of strain and orbital magnetic moments.",2203.16061v1
+2022-04-07,High-throughput computational discovery of 40 ultralow thermal conductivity and 20 highly anisotropic crystalline materials,"We performed ab-initio driven density functional theory-based high throughput
+computations to search for materials with low thermal conductivity and high
+thermal transport anisotropy. We shortlisted a pool of 429 stable ternary
+semiconductors from the Materials Project and obtained phonon thermal
+conductivity by solving the Boltzmann transport equation on 225 materials. We
+found the lowest thermal conductivity of 0.16 W/m-K in SbRbK 2 and 40 materials
+with a thermal conductivity lower than 1 W/m-K at 300 K. For anisotropic
+thermal transport, we have identified six materials with anisotropy larger than
+5 and 20 with thermal transport anisotropy higher than the largest reported
+literature value.",2204.03628v2
+2022-04-09,Learning hyperelastic anisotropy from data via a tensor basis neural network,"Anisotropy in the mechanical response of materials with microstructure is
+common and yet is difficult to assess and model. To construct accurate response
+models given only stress-strain data, we employ classical representation
+theory, novel neural network layers, and L1 regularization. The proposed
+tensor-basis neural network can discover both the type and orientation of the
+anisotropy and provide an accurate model of the stress response. The method is
+demonstrated with data from hyperelastic materials with off-axis transverse
+isotropy and orthotropy, as well as materials with less well-defined symmetries
+induced by fibers or spherical inclusions. Both plain feed-forward neural
+networks and input-convex neural network formulations are developed and tested.
+Using the latter, a polyconvex potential can be established, which, by
+satisfying the growth condition can guarantee the existence of boundary value
+problem solutions.",2204.04529v1
+2022-04-11,Aharonov-Bohm oscillations in phosphorene quantum rings: mass anisotropy compensation by confinement potential,"We consider the Aharonov-Bohm (AB) effect on a confined electron ground state
+in a quantum ring defined electrostatically within the phosphorene monolayer.
+The strong anisotropy of effective masses in phosphorene quenches ground-state
+oscillations for a circular ring because of interrupted persistent current
+circulation around the ring. An elliptic deformation of the confinement
+potential can compensate for the anisotropy of the effective masses and produce
+ground-state parity transformations with the AB periodicity. Moreover, a
+specific ratio of the semiaxes is determined for which the spectrum becomes
+identical to that of a circular quantum ring and an isotropic effective mass.
+We identify a generalized angular momentum operator which commutes with the
+continuum Hamiltonian for the chosen ratio of the semi-axes that closes the
+avoided crossings of energy levels for states of the same parity and spin.
+Ground-state oscillations for the two-electron ground state are also discussed.",2204.05364v1
+2022-05-03,"Carrier Doping Modulates 2D Intrinsic Ferromagnetic Mn2Ge2Te6 Monolayer High Curie Temperature, Large Magnetic Crystal Anisotropy","The Mn2Ge2Te6 shows intrinsic ferromagnetic (FM) order, with Curie
+temperature (Tc) of 316 K. The FM order origins from superexchange interaction
+between Mn and Te atoms. Mn2Ge2Te6 is half-metal (HM), and spin-\b{eta}
+electron is a semiconductor with gap of 1.462 eV. Mn2Ge2Te6 tends in-plane
+anisotropy (IPA), with magnetic anisotropy energy (MAE) of -13.2 meV/f.u.. The
+Mn2Ge2Te6 shows good dynamical and thermal stability. Moreover, Mn2Ge2Te6
+presents good ferromagnetic and half-metallic stability under charge doping.
+The carriers doping could effectively tune magnetic and electronic properties.
+Specifically, the magnetic moment, exchange parameter, and MAE could be
+efficiently tuned. The total magnetic moment changes linearly with charges
+doping. The exchange parameters could be controlled by the doping carriers. The
+carriers doping could modulate MAE to -18.4 (+0.4 e), -0.85 (-1.6 e), 1.31
+(-2.4 e) meV/f.u., by changing hybridization between Te atoms' py and pz
+orbitals. Mn2Ge2Te6 with intrinsic ferromagnetism, high tunable MAE, good
+stability of ferromagnetism and half-metallicity could help researchers to
+investigate its wide application in the electronics and spintronics.",2205.01498v1
+2022-05-18,Rectangular and square skyrmion crystals on a centrosymmetric square lattice with easy-axis anisotropy,"We report our theoretical results on the emergence of rectangular- and
+square-shaped magnetic skyrmion crystals on a centrosymmetric square lattice
+with magnetic anisotropy. By performing the simulated annealing for a
+frustrated spin model with an easy-axis single-ion anisotropy on a square
+lattice, we find that a competition of the interactions in momentum space gives
+rise to the formation of two skyrmion crystals, where the skyrmion cores are
+aligned in a rectangle- or square-lattice way. Especially, the interactions at
+the higher harmonic wave vectors play an important role in stabilizing the
+square/rectangular skyrmion crystals. Our results provide a reference to
+explore further skyrmion-hosting materials in centrosymmetric tetragonal
+systems.",2205.09236v1
+2022-05-27,Fourfold anisotropic magnetoresistance of L1$_0$ FePt due to relaxation time anisotropy,"Experimental measurements show that the angular dependence of the anisotropic
+magnetoresistance (AMR) in L1$_0$ ordered FePt epitaxial films on the current
+orientation and magnetization direction is a superposition of the corresponding
+dependences of twofold and fourfold symmetries. The twofold AMR exhibits a
+strong dependence on the current orientation, whereas the fourfold term only
+depends on the magnetization direction in the crystal and is independent of the
+current orientation. First-principles calculations reveal that the fourfold AMR
+arises from the relaxation time anisotropy due to the variation of the density
+of states near the Fermi energy under rotation of the magnetization. This
+relaxation time anisotropy is a universal property in ferromagnetic metals and
+determines other anisotropic physical properties that are observable in
+experiment.",2205.13767v1
+2022-05-31,Anisotropy driven response of skyrmion lattice in MnSc$_2$S$_4$ to applied magnetic fields,"We theoretically and experimentally study the stability of the unconventional
+fractional antiferromagnetic skyrmion lattice (AF-SkL) in Mn$_2$S$_4$ spinel
+under magnetic fields applied along the $[$1-10$]$ crystal direction. By
+performing numerical Monte Carlo simulations for the minimal effective spin
+model that we proposed in Ref. [S. Gao, et al., Nature 586, 37-41 (2020)], we
+show that the skyrmion lattice is aligned within the equivalent and symmetric
+$[$1-11$]$ or $[$1-11$]$ planes, which are equally inclined to the applied
+magnetic field. We attribute this behavior to the magnetic anisotropy of the
+host material. Neutron single crystal diffraction presents a very good
+agreement with the predictions of the effective model. It reveals that the
+topological spin texture gets destabilized at low temperatures and moderate
+magnetic fields and is replaced by a conical phase for B// $[$1-10$]$. The
+present study elucidates the central role of the magnetic anisotropy in the
+stabilization of antiferromagnetic skyrmionic states.",2205.15787v1
+2022-07-02,Scaling Relations and Topological Quadruple Points in Light-matter Interactions with Anisotropy and Nonlinear Stark Coupling,"Universality is a common quality in different physical parameters that is
+rooted in the deep nature of physical systems. Scaling relation is a typical
+universality for critical phenomena around a quantum phase transition, while
+topological classification provides another type of universality essentially
+different from the critical universality. Both classes of universalities can be
+present in a single-qubit system with light-matter interactions, as exhibiting
+generally in the fundamental quantum Rabi model with anisotropy not only for
+linear coupling but also for nonlinear Stark coupling (NSC). In low frequencies
+different levels of scaling relations are demonstrated, holding for anisotropic
+or/and NSCs, locally or globally. At finite frequencies such a critical
+universality breaks down and diversity is dominant. However, common topological
+feature of the ground state can be extracted from the node number, which yields
+a topological class of universality amidst the critical diversity. Both
+conventional and unconventional topological transitions emerge, with their
+meeting, which never occurs in linear interaction, enabled by the nonlinear
+coupling to form topological quadruple points which are found to be
+spin-invariant points. Sensitivity analysis indicates that the NSC can be
+another approach to manipulate topological transitions in addition to coupling
+anisotropy.",2207.00904v1
+2022-07-19,Spatially flat universes with isotropic tidal forces,"We investigate the dynamics of the spatially flat universes submitted to
+isotropic tidal forces and adiabatic expansion under Einstein's equations.
+Surprisingly, the tendency to a high Hubble anisotropy at late times starts to
+appear as far as we assume the strong energy condition, a characteristic which
+becomes dominant in the radiation era and even more stringent under a stiff
+matter regime. We introduce the parameter b which measures the relative change
+in the magnitudes of the Hubble anisotropy and the scale factor and use it to
+show that the anisotropies must be kept small as long as we assume the Universe
+has passed through an inflationary period, in accordance with the cosmic
+no-hair theorem. Hence, we have a class of models that shows us a simple and
+straightforward way the instability of the FLRW universes, the furtiveness of
+the isotropy concept, and how they can still be consistent with the standard
+model of Cosmology as far as we assume the occurrence of an inflationary early
+period.",2207.09279v1
+2022-08-11,Magneto-anisotropic weak antilocalization in near-surface quantum wells,"We investigate the effects of an in-plane magnetic field on the weak
+antilocalization signature of near-surface quantum wells lacking bulk and
+inversion symmetry. The measured magnetoconductivity exhibits a strong
+anisotropy with respect to the direction of the in-plane magnetic field. The
+two-fold symmetry of the observed magneto-anisotropy originates from the
+competition between Rashba and Dresselhaus spin-orbit couplings. The high
+sensitivity of the weak antilocalization to the spin texture produced by the
+combined Zeeman and spin-orbit fields results in very large anisotropy ratios,
+reaching 100%. Using a semiclassical universal model in quantitative agreement
+with the experimental data, we uniquely determine the values of the Dresselhaus
+and Rashba parameters as well as the effective in-plane g-factor of the
+electrons. Understanding these parameters provides new prospects for novel
+applications ranging from spintronics to topological quantum computing.",2208.06050v3
+2022-08-21,Origin of anisotropic diffusion in Turing Patterns,"In this paper, we numerically study Turing patterns by the Finsler geometry
+(FG) modeling technique on thermally fluctuating triangular lattices, which are
+often used for modeling cell membranes or lipid membranes, focusing on the
+origin of diffusion anisotropy. The FG modeling prescription allows us to
+assume direction-dependent diffusion described by Laplacian. To implement such
+diffusion anisotropy in the FG modeling, we need an internal degree of freedom
+(IDF), which depends on direction and position and is controlled by some
+external forces or stimuli. For such a direction-dependent IDF, we use velocity
+directions corresponding to thermal fluctuations of the lattice vertices. We
+find that anisotropic Turing patterns emerge in the direction along which
+vertices fluctuate. In the simulations, direction-dependent diffusion
+coefficients are unnecessary for input, and instead, the IDF aligns the
+direction of vertex fluctuation along a direction implemented by external
+stimuli. Our results and techniques provide insight into the origin of
+diffusion anisotropy connected to Turing patterns.",2208.09977v1
+2022-08-22,Gauge Theory Couplings on Anisotropic Lattices,"The advantage of simulating lattice field theory with quantum computers is
+hamstrung by the limited resources that induce large errors from finite volume
+and sizable lattice spacings. Previous work has shown how classical simulations
+near the Hamiltonian limit can be used for setting the lattice spacings in
+real-time through analytical continuation, thereby reducing errors in quantum
+simulations. In this work, we derive perturbative relations between bare and
+renormalized quantities in Euclidean spacetime at any anisotropy factor -- the
+ratio of spatial to temporal lattice spacings -- and in any spatial dimension
+for $U(N)$ and $SU(N)$. This reduces the required classical preprocessing for
+quantum simulations. We find less than $10\%$ discrepancy between our
+perturbative results and those from existing nonperturbative determinations of
+the anisotropy for $SU(2)$ and $U(1)$ gauge theories. For the discrete groups
+$\mathbb{Z}_{10}$, $\mathbb{Z}_{100}$ and $\mathbb{BI}$, we perform lattice
+Monte Carlo simulations to extract anisotropy factors and observe similar
+agreement with our perturbative results.",2208.10417v1
+2022-08-23,Translational Symmetry Broken Magnetization Plateau of the $S=2$ Antiferromagnetic Chain with Anisotropies,"The magnetization plateau of the $S=2$ antiferromagnetic chain with
+interaction and single-ion anisotropies is investigated using the numerical
+diagonalization of finite-size clusters and some size scaling analyses. The
+previous level spectroscopy analysis indicated that two different magnetization
+plateau phases appear at half of the saturation magnetization. One is due to
+the large-$D$ mechanism and the other is due to the Haldane one. In the present
+study the phase diagram is extended to wider region of the anisotropies. As a
+result we find another half magnetization plateau phase, where the
+translational symmetry is spontaneously broken .",2208.10983v1
+2022-09-01,"Uniaxial strain, topological band singularities and pairing symmetry changes in superconductors","Uniaxial strain affects pairing symmetry states in superconductors by
+changing the lattice symmetry, and by altering Fermi surface topology. Here, we
+present a systematic study of these effects within a one-band negative-U
+Hubbard model for s, p and d-wave pairing states. We consider a general 2D
+model that can be applied to superconductors under uniaxial strain, modelled
+via hopping anisotropy, on a square lattice. The results presented here model
+an in plane compression along the x-axis, which reduces the lattice symmetry
+from a tetragonal to an orthorhombic crystal space group. The effects of
+hopping anisotropy on the different types of gap pairings are explored. We show
+that changes in Tc are tunable with hopping anisotropy and depend on the
+orientation of the gap function in relation to the opening of the Fermi surface
+during the Lifshitz transition. In comparing the model results to experimental
+data for the case of Sr2RuO4 it is found that both the d + id and d + ig
+pairings best describe the changes in Tc for the superconducting state in
+regards to its response to small uniaxial strain.",2209.00300v1
+2022-09-13,Anisotropic warm inflation,"Anisotropic inflation is a model succeeded in explaining statistical
+anisotropy. Warm inflation is a model succeeded in providing a mechanism of
+reheating during inflation. We study anisotropic warm inflation focusing on the
+cosmic no-hair conjecture. In the anisotropic warm inflation, the condition for
+making anisotropy survived is clarified. By assuming a constant value for the
+dissipation ratio, we find exact solutions of power-law anisotropic warm
+inflation, and investigate the phase space structure of general solutions. It
+turns out that whether the anisotropy during inflation survives or not depends
+on the competition of the potential that drive anisotropic inflation against
+dissipation of an inflaton field. Anisotropic warm inflation will be realized
+if the decaying process is not efficient.",2209.05776v2
+2022-09-17,Temperature-driven changes in the Fermi surface of graphite,"We report on temperature-dependent size and anisotropy of the Fermi pockets
+in graphite revealed by magnetotransport measurements. The magnetoresistances
+obtained in fields along the c-axis obey an extended Kohler's rule, with the
+carrier density following prediction of a temperature-dependent Fermi energy,
+indicating a change in the Fermi pocket size with temperature. The
+angle-dependent magnetoresistivities at a given temperature exhibit a scaling
+behavior. The scaling factor that reflects the anisotropy of the Fermi surface
+is also found to vary with temperature. Our results demonstrate that
+temperature-driven changes in Fermi surface can be ubiquitous and need to be
+considered in understanding the temperature-dependent carrier density and
+magnetoresistance anisotropy in semimetals.",2209.08406v1
+2022-09-20,Elastic anisotropy of lizardite at subduction zone conditions,"Subduction zones transport water into Earth's deep interior through slab
+subduction. Serpentine minerals, the primary hydration product of ultramafic
+peridotite, are abundant in most subduction zones. Characterization of their
+high-temperature elasticity, particularly their anisotropy, will help us better
+estimate the extent of mantle serpentinization and the Earth's deep water
+cycle. Lizardite, the low-temperature polymorph of serpentine, is stable under
+the P-T conditions of cold subduction slabs (< 260{\deg}C at 2 GPa), and its
+high-temperature elasticity remains unknown. Here we report ab initio
+elasticity and acoustic wave velocities of lizardite at P-T conditions of
+subduction zones. Our static results agree with previous studies. Its
+high-temperature velocities are much higher than previous experimental-based
+lizardite estimates with chrysotile but closer to antigorite velocities. The
+elastic anisotropy of lizardite is much larger than that of antigorite and
+could better account for the observed large shear-wave splitting in some cold
+slabs such as Tonga.",2209.09783v1
+2022-09-22,Spin wave study of magnetic perpendicular surface anisotropy in single crystalline MgO$\text{/}$Fe$\text{/}$MgO films,"Broadband ferromagnetic resonance is measured in single crystalline Fe films
+of varying thickness sandwiched between MgO layers. An exhaustive magnetic
+characterization of the films (exchange constant, cubic, uniaxial and surface
+anisotropies) is enabled by the study of the uniform and the first
+perpendicular standing spin wave modes as a function of applied magnetic field
+and film thickness. Additional measurements of non-reciprocal spin wave
+propagation allow us to separate each of the two interface contributions to the
+total surface anisotropy. The results are consistent with the model of a
+quasi-bulk film interior and two magnetically different top and bottom
+interfaces, a difference ascribed to different oxidation states.",2209.10906v2
+2022-09-28,"One $μ$ to rule them all: CMB spectral distortions can probe domain walls, cosmic strings and low scale phase transitions","We present a new probe of purely gravitationally coupled sectors with large
+anisotropies. These anisotropies are damped via gravitational interactions with
+the baryon-photon fluid, which is heated up in the process. The injected heat
+causes measurable distortions of the cosmic microwave background spectrum. We
+give analytic estimates for the size of the distortions and outline how to
+calculate them from first principles. These methods are applied to anisotropies
+in the form of a domain wall/cosmic string network or caused by a first order
+phase transition or scalar field dynamics. We find that this method can
+potentially probe large regions of previously unconstrained parameter space and
+is very much complementary to up-coming searches of gravitational waves caused
+by such dark sectors.",2209.14313v2
+2022-10-16,Phase transitions in 3-dimensional Dirac semi-metals using Schwinger-Dyson equations,"We study the semi-metal/insulator quantum phase transition in
+three-dimensional Dirac semi-metals by solving a set of Schwinger-Dyson
+equations. We study the effect of an anisotropic fermion velocity on the
+critical coupling of the transition. We consider the influence of several
+different approximations that are commonly used in the literature and show that
+results for the critical coupling change considerably when some of these
+approximations are relaxed. Most importantly, the nature of the dependence of
+the critical coupling on the anisotropy depends strongly on the approximations
+that are used for the photon polarization tensor. On the one hand, this means
+that calculations that include full photon dynamics are necessary to answer
+even the basic question of whether the critical coupling increases or decreases
+with anisotropy. On the other hand, our results mean that it is possible that
+anisotropy could provide a mechanism to promote dynamical gap generation in
+realistic three-dimensional Dirac semi-metallic materials.",2210.08563v2
+2022-10-21,Anisotropy and crystallite misalignment in textured superconductors,"A misalignment of anisotropic crystallites causes small values of anisotropy
+and decreases the critical current density of textured polycrystalline
+superconductors. To relate the crystallite misalignment and out-plane
+anisotropy, the magnetic properties of the textured Bi2223 polycrystalline
+superconductor were investigated. A distribution of orientation angles of
+crystallites was determined using different data: scanning electron microscopy
+images and hysteresis magnetization loops when an external magnetic field was
+applied at different angles with respect to the texturing plane of the sample.
+It was demonstrated that the standard deviation of the distribution and the
+magnetic disorder angle of crystallites in textured samples can be determined
+from the magnetization data in perpendicular directions. These data may be
+either the irreversible magnetization measured for two different orientations
+of the sample or the simultaneously measured magnetization projections parallel
+and perpendicular to the magnetic field.",2210.11712v1
+2022-10-30,"Interplay of symmetry-conserved tunneling, interfacial oxidation and perpendicular magnetic anisotropy in CoFeB/MgO-based junctions","The interfacial oxidation level and thermodynamic properties of the MgO-based
+perpendicular magnetic tunneling junctions are investigated. The
+symmetry-conserved tunneling effect depends sensitively on the MgO adatom
+energy during the RF sputtering, as well as the thermal stability of the
+structure during the post-growth thermal annealing. Two different failure modes
+of the magnetoresistance are highlighted, involving with the decay of
+perpendicular magnetic anisotropy and destruction of coherent tunneling
+channels, respectively. Through the careful control of interfacial oxidation
+level and proper selection of the heavy metal layers, both perpendicular
+magnetic anisotropy and tunneling magnetoresistance of the junctions can be
+increased.",2210.16734v1
+2022-11-04,In-plane anisotropy of electrical transport in Y$_{0.85}$Tb$_{0.15}$Ba$_2$Cu$_3$O$_{7-x}$ films,"We fabricate high-quality c-axis oriented epitaxial YBa$_2$Cu$_3$O$_{7-x}$
+films with 15% of yttrium atoms replaced by terbium (YTBCO) and study their
+electrical properties. The Tb substitution reduces the charge carrier density
+resulting in increased resistivity and decreased critical current density
+compared to the pure YBa$_2$Cu$_3$O$_{7-x}$ films. The electrical properties of
+the YTBCO films show an in-plane anisotropy in both the superconducting and
+normal state providing evidence for the twin-free film. Unexpectedly, the
+resistive transition of the bridges also demonstrates the in-plane anisotropy
+that can be explained within the framework of Tinkham's model of the resistive
+transition and the Berezinskii-Kosterlitz-Thouless (BKT) model depending on the
+sample parameters. We consider YTBCO films to be a promising platform for both
+the fundamental research on the BKT transition in the cuprate superconductors
+and for the fabrication of devices with high kinetic inductance.",2211.02564v2
+2022-11-15,A Tilt Instability in the Cosmological Principle,"We show that the Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) framework has
+an instability towards the growth of fluid flow anisotropies, even if the
+Universe is accelerating. This flow (tilt) instability in the matter sector is
+invisible to Cosmic No-Hair Theorem-like arguments, which typically only flag
+shear anisotropies in the metric. We illustrate our claims in the setting of
+``dipole cosmology'', the maximally Copernican generalization of FLRW that can
+accommodate a flow. Simple models are sufficient to show that the cosmic flow
+need not track the shear, even in the presence of a positive cosmological
+constant. We also emphasize that the growth of the tilt hair is fairly generic
+if the total equation of state $w(t) \rightarrow -1$ at late times (as it does
+in standard cosmology), irrespective of the precise model of dark energy. The
+generality of our theoretical result puts various recent observational claims
+about late time anisotropies and cosmic dipoles in a new light.",2211.08093v2
+2022-11-17,Large Primordial Fluctuations in Gravitational Waves from Phase Transitions,"It is well-known that first order phase transitions in the early universe can
+be a powerful source of observable stochastic gravitational wave backgrounds.
+Any such gravitational wave background must exhibit large-scale anisotropies at
+least as large as those seen in the CMB $\sim 10^{-5}$, providing a valuable
+new window onto the (inflationary) origins of primordial fluctuations. While
+significantly larger fractional anisotropies are possible (for example, in
+multi-field inflation) and would be easier to interpret, it has been argued
+that these can only be consistent with CMB bounds if the gravitational wave
+signal is correspondingly smaller. In this paper, we show that this argument,
+which relies on assuming radiation dominance of the very early universe, can be
+evaded if there is an era of early matter dominance of a certain robust type.
+This allows large gravitational wave anisotropies to be consistent with
+observable signals at proposed future gravitational wave detectors. Constraints
+from the CMB on large scales, as well as primordial black hole and mini-cluster
+formation on small scales, and secondary scalar-induced gravitational waves are
+all taken into account.",2211.09301v1
+2022-11-21,Magnetocaloric effect at the reorientation of the magnetization in ferromagnetic multilayers with perpendicular anisotropy,"We investigate the magnetocaloric effect obtained by the rotation of a
+magnetic field applied to an exchange-coupled multilayer system composed of two
+different ferromagnetic (FM) materials. We specifically consider a system in
+which the two FMs have perpendicular uniaxial anisotropy axes and utilise
+conditions which yield a reorientation of the total magnetization when
+compensation between the anisotropies of the two layers occurs. We calculate
+the consequent entropy change associated with the ""artificial"" reorientation.
+By using known parameters from MnBi and Co we predict an entropy change of
+$\Delta s = 0.34$ Jkg$^{-1}$K$^{-1}$ for perfect coupling. Lastly, we study the
+behavior of the multilayer under a rotating magnetic field via a micromagnetic
+model. When the layer thicknesses are of the order of the local domain wall
+width, the magnetic field-induced entropy change can be obtained with magnetic
+fields one order of magnitude lower than in the uncoupled case.",2211.11146v3
+2022-11-21,Ferromagnetic frozen structures from the dipolar hard spheres fluid at moderate and small volume fractions,"We study the magnetic phase diagram of an ensemble of dipolar hard spheres
+(DHS) with or without uniaxial anisotropy and frozen in position on a
+disordered structure by tempered Monte Carlo simulations. The crucial point is
+to consider an anisotropic structure, obtained from the liquid state of the
+dipolar hard spheres fluid, frozen in its polarized state at low temperature.
+The freezing inverse temperature $\beta_f$ determines the degree of anisotropy
+of the structure which is quantified through a structural nematic order
+parameter, $\lambda_s$. The case of the non zero uniaxial anisotropy is
+considered only in its infinitely strong strength limit where the system
+transforms in a dipolar Ising model (DIM). The important finding of this work
+is that both the DHS and the DIM with a frozen structure build in this way
+present a ferromagnetic phase at volume fractions below the threshold value
+where the corresponding isotropic DHS systems exhibit a spin glass phase at low
+temperature.",2211.11268v4
+2022-11-29,Mechano-lithography: stress anisotropy driven nematic order in growing three-dimensional bacterial biofilms,"Living active collectives have evolved with remarkable self-patterning
+ability to meet the physical and biological constraints for growth and
+survival. However, how complex multicellular patterns emerge from a single
+founder cell remains elusive. Here, by recourse to an agent-based model, we
+track the three-dimensional (3D) morphodynamics and cell orientational order of
+growing bacterial biofilms encased by agarose gels. Confined growth causes
+spatiotemporally heterogeneous stress buildup in the biofilm. High hydrostatic
+and low shear stresses at the core of the biofilm promote viscous-to-elastic
+transition and randomize cell packing, whereas the opposite stress state near
+the gel-cell interface drives nematic ordering with a time delay inherent to
+shear stress relaxation. Overall, stress anisotropy spatiotemporally coincides
+with nematic order in the confined biofilms, suggesting an
+anisotropic-stress-driven ordering mechanism. The strong reciprocity between
+stress anisotropy and cell ordering inspires innovative 3D mechano-lithography
+of living active collectives for a variety of environmental and biomedical
+applications.",2211.16354v1
+2022-11-30,Supercurrent-induced Anomalous Thermal Hall Effect as a New Probe to Superconducting Gap Anisotropy,"Two-dimensional superconductors have been realized in various atomically thin
+films such as the twisted bilayer graphene, some of which are anticipated to
+involve unconventional pairing mechanism. Due to their low dimensionality,
+experimental probes of the exact nature of superconductivity in these systems
+have been limited. We propose, by applying a \emph{vertical} supercurrent to a
+bilayer superconductor where the mirror symmetry is naturally broken by the
+twisting, there will be anomalous thermal Hall effect induced by the
+supercurrent that can serve as a sharp probe for the \emph{in-plane} anisotropy
+of the superconducting gap function. This effect occurs in the \emph{absence}
+of an external magnetic field and spontaneous breaking of the time-reversal
+symmetry in the ground state. We derive explicit formulas for the induced
+thermal Hall conductivity and show them to be significant in the examples of
+twisted cuprates and twisted FeSe where monolayer superconductivity have
+already been observed. Though technical challenges still exist, we propose this
+to be a generic probe of the gap anisotropy in a twisted bilayer
+superconductor.",2211.16651v2
+2022-12-02,Anisotropic Van der Waals 2D GeAs Integrated on Silicon Four-Waveguide Crossing,"In-plane optical anisotropy plays a critical role in manipulating light in a
+wide range of planner photonic devices. In this study, the strong anisotropy of
+multilayer 2D GeAs is leveraged and utilized to validate the technical
+feasibility of on-chip light management. A 2D GeAs is stamped into an
+ultra-compact silicon waveguide four-way crossing optimized for operation in
+the O-optical band. The measured optical transmission spectra indicated a
+remarkable discrepancy between the in-plane crystal optical axes with an
+attenuation ratio of ~ 3.5 (at 1330 nm). Additionally, the effect of GeAs
+crystal orientation on the electro-optic transmission performance is
+demonstrated on a straight waveguide. A notable 50 % reduction in responsivity
+was recorded for devices constructed with cross direction compared to devices
+with a crystal a-direction parallel to the light polarization. This
+extraordinary optical anisotropy, combined with a high refractive index ~ 4 of
+2D GeAs, opens possibilities for efficient on-chip light manipulation in
+photonic devices.",2212.01154v1
+2022-12-06,Spatially Homogeneous Universes with Late-Time Anisotropy,"The cosmological principle asserts that on sufficiently large scales the
+Universe is homogeneous and isotropic on spatial slices. To deviate from this
+principle requires a departure from the FLRW ansatz. In this paper we analyze
+the cosmological evolution of two spatially homogeneous but anisotropic
+universes, namely the spatially closed Kantowski-Sachs Universe and the open
+axisymmetric Bianchi type III Universe. These models are characterized by two
+scale factors and we study their evolution in universes with radiation, matter
+and a cosmological constant. In all cases, the two scale factors evolve
+differently and this anisotropy leads to a lensing effect in the propagation of
+light. We derive explicit formulae for computing redshifts, angular diameter
+distances and luminosity distances and discuss the predictions of these models
+in relation to observations for type Ia supernovae and the CMB. We comment on
+the possibility of explaining the observed luminosity distance plot for type Ia
+supernovae within the context of cosmologies featuring late-time anisotropy and
+a vanishing cosmological constant.",2212.03234v3
+2023-01-16,Probing the Blue Axion with Cosmic Optical Background Anisotropies,"A radiative decaying Big Bang relic with a mass $m_a\simeq 5-25 \,\rm eV$,
+which we dub ""blue axion"", can be probed with direct and indirect observations
+of the cosmic optical background (COB). The strongest bounds on blue-axion cold
+dark matter come from the Hubble Space Telescope (HST) measurements of COB
+anisotropies at $606$~nm. We suggest that new HST measurements at higher
+frequencies ($336$~nm and $438$~nm) can improve current constraints on the
+lifetime up to one order of magnitude, and we show that also thermally produced
+and hot relic blue axions can be competitively probed by COB anisotropies. We
+exclude the simple interpretation of the excess in the diffuse COB detected by
+the Long Range Reconnaissance Imager (LORRI) as photons produced by a decaying
+hot relic. Finally, we comment on the reach of upcoming line intensity mapping
+experiments, that could detect blue axions with a lifetime as large as
+$10^{29}\,\rm s$ or $10^{27}\,\rm s$ for the cold dark matter and the hot relic
+case, respectively.",2301.06560v2
+2023-01-17,"Observation of field-induced single-ion magnetic anisotropy in a multiorbital Kondo alloy $\mathrm{(Lu,Yb)}\mathrm{Rh}_{2}\mathrm{Zn}_{20}$","We demonstrate field-induced single-ion magnetic anisotropy resulting from
+the multiorbital Kondo effect on the diluted ytterbium alloy
+$(\mathrm{Lu}_{1-x}\mathrm{Yb}_x)\mathrm{Rh}_2\mathrm{Zn}_{20}$. Single-ion
+anisotropic metamagnetic behavior is revealed in low-temperature regions where
+the local Fermi-liquid state is formed. Specific hea, low-field magnetic
+susceptibility, and resistivity indicate reproduction of the ground-state
+properties by the $\mathrm{SU}(N = 8)$ Kondo model with a relatively large
+$c$-$f$ hybridization of $T_{\mathrm{K}} = 60.9 \ \mathrm{K}$. Dynamical
+susceptibility measurements on $\mathrm{Yb}\mathrm{Rh}_2\mathrm{Zn}_{20}$
+support realizing the multiorbital Kondo ground state in
+$(\mathrm{Lu}_{1-x}\mathrm{Yb}_x)\mathrm{Rh}_2\mathrm{Zn}_{20}$. The single-ion
+magnetic anisotropy becomes evident above $\sim5 \ \mathrm{T}$, which is lower
+than the isotropic Kondo crossover field of 22.7 T, verifying blurred low-lying
+crystal field states through the multiorbital Kondo effect.",2301.07038v3
+2023-01-31,Validating dark energy models using polarised Sunyaev-Zel'dovich effect with large-angle CMB temperature and E-mode polarization anisotropies,"The tomography of the polarized Sunyaev-Zeldvich effect due to free electrons
+of galaxy clusters can be used to constrain the nature of dark energy because
+CMB quadrupoles at different redshifts as the polarization source are sensitive
+to the integrated Sachs-Wolfe effect. Here we show that the low multipoles of
+the temperature and E-mode polarization anisotropies from the all-sky CMB can
+improve the constraint further through the correlation between them and the CMB
+quadrupoles viewed from the galaxy clusters. Using a Monte-Carlo simulation, we
+find that low multipoles of the temperature and E-mode polarization
+anisotropies potentially improve the constraint on the equation of state of
+dark energy parameter by $\sim 17$ percent.",2301.13676v1
+2023-02-08,Scanning Reflectance Anisotropy Microscopy for Multi-Material Strain Mapping,"Strain-engineering of materials encompasses significant elastic deformation
+and leads to breaking of the lattice symmetry and as a consequence to the
+emergence of optical anisotropy. However, the capability to image and map local
+strain fields by optical microscopy is currently limited to specific materials.
+Here, we introduce a broadband scanning reflectance anisotropy microscope as a
+phase-sensitive multi-material optical platform for strain mapping. The
+microscope produces hyperspectral images with diffraction-limited sub-micron
+resolution of the near-normal incidence ellipsometric response of the sample,
+which is related to elastic strain by means of the elasto-optic effect. We
+demonstrate cutting edge strain sensitivity using a variety of materials, such
+as metasurfaces, semiconductors and metals. The versatility of the method to
+study the breaking of the lattice symmetry by simple reflectance measurements
+opens up the possibility to carry out non-destructive mechanical
+characterization of multi-material components, such as wearable electronics and
+optical semiconductor devices.",2302.04095v2
+2023-02-11,Modelling the emergence of cosmic anisotropy from non-linear structures,"Astronomical observations suggest that the Universe may be anisotropic on the
+largest scales. In order to model this situation, we develop a new approach to
+cosmology that allows for large-scale anisotropy to emerge from the growth of
+non-linear structure. This is achieved by decomposing all relevant fields with
+respect to a preferred space-like direction, and then averaging the resulting
+scalar quantities over spatial domains. Our approach allows us to derive a set
+of large-scale effective field equations that govern the dynamics of any
+emergent large-scale anisotropy, and which (up to back-reaction terms) take the
+form of the field equations of the locally rotationally symmetric Bianchi
+cosmologies. We apply our approach to the dust-filled Farnsworth solutions,
+which are an interesting set of exact cosmological models that allow for both
+anisotropic expansion and large-scale bulk flow.",2302.05715v2
+2023-03-06,An upscaling based three parameter elastic anisotropy model,"Rock formations often exhibit transversely anisotropic elastic behavior due
+to their layered structure. Such materials are characterized by five
+independent elastic constants. In the context of petroleum applications, it is
+often challenging to accurately measure all these elastic parameters. At the
+same time, the effect of elastic anisotropy can be noticeable and therefore
+there is a need to include it in some form. To fill the gap, this study
+proposes a three parameter elastic anisotropy model. It captures the dominant
+anisotropic behavior and yet has only three elastic constants that are
+relatively easy to measure in laboratory. The approach is based on upscaling of
+a periodically layered material characterized by equal height layers with
+different Young's moduli and the same Poisson's ratio. The resultant upscaled
+material is transversely isotropic and is also physically admissible. The
+developed approach allows to effectively reconstruct or estimate the values of
+the two remaining parameters needed for the transversely isotropic model.
+Comparison between the reconstructed results and the measured values are
+compared for several rock types.",2303.03236v1
+2023-03-07,Jet polarisation in an anisotropic medium,"We study the evolution of an energetic jet which propagates in an anisotropic
+quark-gluon plasma, as created in the intermediate stages of ultrarelativistic
+heavy-ion collisions. We argue that the partons of the jet should acquire a
+non-zero average polarisation proportional to the medium anisotropy. We first
+observe that the medium anisotropy introduces a difference between the rates
+for transverse momentum broadening along the two directions perpendicular to
+the jet axis. In turn, this difference leads to a polarisation-dependent bias
+in the BDMPS-Z rates for medium-induced gluon branching. Accordingly, the
+daughter gluons in a branching process can carry net polarisation even if their
+parent gluon was unpolarised. Using these splitting rates, we construct kinetic
+equations which describe the production and transmission of polarisation via
+multiple branching in an anisotropic medium. The solutions to these equations
+show that polarisation is efficiently produced via quasi-democratic branchings,
+but then it is rapidly washed out by the subsequent branchings, due to the
+inability of soft gluons to keep trace of the polarisation of their parents.
+Based on that, we conclude that a net polarisation for the jet should survive
+in the final state if and only if the medium anisotropy is sizeable as the jet
+escapes the medium.",2303.03914v1
+2023-04-01,Itinerant ferromagnetism entrenched by the anisotropy of spin-orbit coupling in a dipolar Fermi gas,"We investigate the the itinerant ferromagnetism in a dipolar Fermi atomic
+system with the anisotropic spin-orbit coupling (SOC),which is traditionally
+explored with isotropic contact interaction.We first study the ferromagnetism
+transition boundaries and the properties of the ground states through the
+density and spin-flip distribution in momentum space, and we find that both the
+anisotropy and the magnitude of the SOC play an important role in this process.
+We propose a helpful scheme and a quantum control method which can be applied
+to conquering the difficulties of previous experimental observation of
+itinerant ferromagnetism. Our further study reveals that exotic Fermi surfaces
+and an abnormal phase region can exist in this system by controlling the
+anisotropy of SOC, which can provide constructive suggestions for the research
+and the application of a dipolar Fermi gas. Furthermore, we also calculate the
+ferromagnetism transition temperature and novel distributions in momentum space
+at finite temperature beyond the ground states from the perspective of
+experiment.",2304.00286v1
+2023-04-03,Magnetic resonance in the quasi-2D square lattice easy-plane antiferromagnet Ba$_2$MnGe$_2$O$_7$,"We report results of a multi-frequency (0.8-60 GHz) electron spin resonance
+study of the spin dynamics in the quasi-2D square lattice antiferromagnet
+Ba$_2$MnGe$_2$O$_7$ both in antiferromagnetically ordered and paramagnetic
+phases. We directly observe two zero-field gaps in the excitation spectrum of
+the ordered phase, the larger one being due to easy-plane anisotropy, and the
+smaller one indicates the presence of fourth-order in-plane anisotropy probably
+related to the multiferroic properties of this compound. We observe effects of
+hyperfine interaction on the electron spin resonance spectra in the
+antiferromagnetically ordered state, which turns out to be comparable with
+in-plane anisotropy. The hyperfine field strength is found from the observed
+low-temperature electron spin resonance data. The spin dynamics of the
+paramagnetic phase is characterized by strong broadening of the ESR absorption
+line, which can be ascribed to the vortex dynamics of a 2D magnet.",2304.01280v1
+2023-04-04,Exploring velocity-spreading factor and consequences through dynamic ray-tracing in general anisotropic media: A comprehensive tutorial,"In seismic imaging, understanding the relationship between
+wavefront-propagation velocity and time-interval velocity is crucial for
+achieving optimal resolution. However, this task becomes even more challenging
+when considering anisotropic situations. To accurately account for the
+influence of anisotropy on wavefronts, it is essential to have a solid grasp of
+the underlying physics. Unfortunately, the anisotropy model that best describes
+the medium is often unknown. To address this issue, we utilize paraxial-ray
+theory in a ray-centered coordinate system to study the wavefront phenomenon.
+This approach allows us to develop explicit expressions that describe the
+physics of the problem. Using this theoretical framework, we can accurately
+generalize the relationship between time-migration rays and Dix velocity by
+incorporating the velocity-spreading factor for general anisotropic media. This
+factor lets us determine the type of anisotropy present in the medium.
+Moreover, the velocity-spreading factor provides valuable information for
+various applications, including model building, time-imaging, and time-to-depth
+conversion. Overall, the presented theoretical framework offers a comprehensive
+understanding of wavefront propagation in anisotropic media, which can aid in
+improving the knowledge of the phenomena that form seismic images.",2304.02069v1
+2023-04-06,Production of Primordial Gravitational Waves in Teleparallel Gravity,"We study the production of primordial gravitational waves in the context of
+extended teleparallel gravity models and compare them with those of general
+relativity. Teleparallel gravity has been widely studied in the context of the
+late universe but not much in the early universe. Two sources of primordial
+gravitational waves are considered, vacuum fluctuations and tensor anisotropies
+within two inflation-compatible backgrounds: a perfect de Sitter and a quasi de
+Sitter background. We find that in the vacuum case with a perfect de Sitter
+background, the gravitational waves propagation equation is the same as that of
+general relativity, however, if the background is promoted to a quasi de Sitter
+background, the propagation equations are different resulting in an important
+difference on the tensor spectral index. When tensor anisotropies are included,
+we compute the most general solution for gravitational waves in terms of a
+retarded Green's function and analyze the contributions to the power spectrum
+from these anisotropies. Finally, we investigate the energy density of these
+gravitational waves.",2304.03067v2
+2023-05-18,Azimuthal Anisotropy of Magnetic Fields in the Circumgalactic Medium Driven by Galactic Feedback Processes,"We use the TNG50 cosmological magnetohydrodynamical simulation of the
+IllustrisTNG project to show that magnetic fields in the circumgalactic medium
+(CGM) have significant angular structure. This azimuthal anisotropy at fixed
+distance is driven by galactic feedback processes that launch strong outflows
+into the halo, preferentially along the minor axes of galaxies. These
+feedback-driven outflows entrain strong magnetic fields from the interstellar
+medium, dragging fields originally amplified by small-scale dynamos into the
+CGM. At the virial radius, $z=0$ galaxies with M$_\star \sim
+10^{10}\,\rm{M_\odot}$ show the strongest anisotropy ($\sim 0.35$ dex). This
+signal weakens with decreasing impact parameter, and is also present but weaker
+for lower mass as well as higher mass galaxies. Creating mock Faraday rotation
+measure (RM) sightlines through the simulated volume, we find that the angular
+RM trend is qualitatively consistent with recent observational measurements. We
+show that rich structure is present in the circumgalactic magnetic fields of
+galaxies. However, TNG50 predicts small RM amplitudes in the CGM that make
+detection difficult as a result of other contributions along the line of sight.",2305.11214v2
+2023-05-24,Competing Uniaxial Anisotropies in Epitaxial Fe Thin Films Grown on InAs(001),"We report on the interplay of two uniaxial magnetic anisotropies in epitaxial
+Fe thin films of varying thickness grown on InAs(001) as observed in
+ferromagnetic resonance experiments. One anisotropy originates from the Fe/InAs
+interface while the other originates from in-plane shear strain resulting from
+the anisotropic relaxation of the Fe film. X-ray diffraction was used to
+measure the in-plane lattice constants of the Fe films, confirming the
+correlation between the onset of film relaxation and the corresponding shear
+strain inferred from ferromagnetic resonance data. These results are relevant
+for ongoing efforts to develop spintronic and quantum devices utilizing large
+spin-orbit coupling in III-V semiconductors.",2305.14648v1
+2023-05-25,Random-anisotropy mixed-spin Ising on a triangular lattice,"We have studied the mixed spin-1/2 and 1 Ising ferrimagnetic system with a
+random anisotropy on a triangular lattice with three interpenetrating
+sublattices $A$, $B$, and $C$. The spins on the sublattices are represented by
+$\sigma_{A}$ (states $\pm1/2$), $\sigma_{B}$ (states $\pm1/2$), and $S_{C}$
+(states $\pm1$, $0$). We have performed Monte Carlo simulations to obtain the
+phase diagram temperature $k_{\text{B}}T/\left|J\right|$ versus the strength of
+the random anisotropy $D/\left|J\right|$. The phase boundary between two
+ferrimagnetic $FR_{1}$ and $FR_{2}$ phases at lower temperatures are always
+first-order for $p<0.25$ and second-order phase transition between the
+$FR_{1}$, $FR_{2}$ and the paramagnetic $P$ phases. On the other hand, for
+values of $p\gtrapprox0.5$, the phase diagram presents only second-order phase
+transition lines.",2305.15866v1
+2023-06-03,Critical behaviours of anisotropic XY ferromagnet in the presence of random field,"The anisotropic XY ferromagnet has been studied by Monte Carlo simulation in
+a three dimensional simple cubic lattice. The increase in critical temperature
+(ferro-para transition) has been noticed with increasing the strength of
+anisotropy. The effects of random fields (both with full circular symmetry and
+in angular window) on the critical temperature are investigated systematically
+in the anisotropic XY ferromagnet in three dimensions. Reduction in the
+critical temperature of anisotropic XY ferromagnet has been observed in the
+presence of random field. The compensating field (the required amount of field
+which preserves the critical temperature for isotropic XY ferromagnet) has been
+studied as a function of the strength of anisotropy. The compensating field was
+found to depend linearly on the strength of anisotropy. We have also studied
+the effects of random field confined in the angular window and observed the
+reduction of the critical temperature with increase of the angular extension.
+The critical behaviours are formalized by the usual finite size analysis and
+the estimation of critical exponents for the susceptibility and the specific
+heat. .",2306.02162v2
+2023-06-13,Reduced energies for thin ferromagnetic films with perpendicular anisotropy,"We derive four reduced two-dimensional models that describe, at
+  different spatial scales, the micromagnetics of ultrathin
+  ferromagnetic materials of finite spatial extent featuring
+  perpendicular magnetic anisotropy and interfacial
+  Dzyaloshinskii-Moriya interaction. Starting with a microscopic model
+  that regularizes the stray field near the material's lateral edges,
+  we carry out an asymptotic analysis of the energy by means of
+  $\Gamma$-convergence. Depending on the scaling assumptions on the
+  size of the material domain vs. the strength of dipolar interaction,
+  we obtain a hierarchy of the limit energies that exhibit
+  progressively stronger stray field effects of the material
+  edges. These limit energies feature, respectively, a renormalization
+  of the out-of-plane anisotropy, an additional local boundary penalty
+  term forcing out-of-plane alignment of the magnetization at the
+  edge, a pinned magnetization at the edge, and, finally, a pinned
+  magnetization and an additional field-like term that blows up at the
+  edge, as the sample's lateral size is increased. The pinning of the
+  magnetization at the edge restores the topological protection and
+  enables the existence of magnetic skyrmions in bounded samples.",2306.07634v2
+2023-06-13,How to cross an energy barrier at zero Kelvin without tunneling effect,"This paper deals with the broad class of magnetic systems having a single or
+collective spin $S$ with an energy barrier, such as Rare-Earth elements and
+their compounds, Single Molecule Magnets with uniaxial anisotropy and more
+generally any other quantum system made of single or multiple objects with
+discrete energy levels. Till now, the reversal of the magnetization of such
+systems at zero Kelvin required to make use of quantum tunneling with a
+significant transverse field or transverse anisotropy term, at resonance. Here,
+we show that another very simple method exists. It simply consists in the
+application of a particular sequence of electromagnetic radiations in the
+ranges of optical or microwave frequencies, depending on the characteristics of
+the system (spin and anisotropy values for magnetic systems). This produces
+oscillations of the Rabi type that pass above the barrier, thus extending these
+oscillations between the two energy wells. with mixtures of all the 2S+1
+states. In addition to its basic character, this approach opens up new
+directions of research in quantum information with possible breakthroughs in
+the current use of multiple quantum bits.",2306.07729v2
+2023-06-22,Collective modes of a collisional anisotropic quark-gluon plasma,"In this paper we consider the collective modes of a momentum-space
+anisotropic quark-gluon plasma taking into account the effect of collisions
+between the plasma constituents. Our analysis is carried out using a
+collisional kernel of Bhatnagar-Gross-Krook form and extends prior analyses in
+the literature by considering all possible angles of propagation of the gluonic
+modes relative to the momentum-anisotropy axis. We extract both the stable and
+unstable modes as a function of the collision rate and confirm prior findings
+that gluonic unstable modes can be eliminated from the spectrum if the
+collision rate is sufficiently large. In addition, we discuss the conditions
+necessary for the existence of unstable modes and present evidence that
+unstable mode growth rates are maximal for modes with momentum along the
+anisotropy direction. Finally, we demonstrate that when there is a finite
+collisional rate, gluonic unstable modes are absent from the spectrum at both
+small and large momentum anisotropy. These results pave the way for
+understanding the impact of collisions on a variety of non-equilibrium
+quark-gluon plasma observables.",2306.12851v2
+2023-07-09,Enhancement and anisotropy of electron Lande factor due to spin-orbit interaction in semiconductor nanowires,"We investigate the effective Lande factor in semiconductor nanowires with
+strong Rashba spin-orbit coupling. Using the $\mathbf{k}\cdot\mathbf{p}$ theory
+and the envelope function approach we derive a conduction band Hamiltonian
+where the tensor $g^*$ is explicitly related to the spin-orbit coupling
+constant $\alpha_R$. Our model includes orbital effects from the Rashba
+spin-orbit term, leading to a significant enhancement of the effective Lande
+factor which is naturally anisotropic. For nanowires based on the low-gap, high
+spin-orbit coupled material InSb, we investigate the anisotropy of the
+effective Lande factor with respect to the magnetic field direction, exposing a
+twofold symmetry for the bottom gate architecture. The anisotropy results from
+the competition between the localization of the envelope function and the spin
+polarization of the electronic state, both determined by the magnetic field
+direction.",2307.04265v2
+2023-07-18,Tilted Spirals and Low Temperature Skyrmions in Cu2OSeO3,"The bulk helimagnet Cu2OSeO3 represents a unique example in the family of B20
+cubic helimagnets exhibiting a tilted spiral and skyrmion phase at low
+temperatures when the magnetic field is applied along the easy <001>
+crystallographic direction. Here we present a systematic study of the stability
+and ordering of these low temperature magnetic states. We focus our attention
+on the temperature and field dependencies of the tilted spiral state that we
+observe persisting up to above T =35 K, i.e. up to higher temperatures than
+reported so far. We discuss these results in the frame of the phenomenological
+theory introduced by Dzyaloshinskii in an attempt to reach a quantitative
+description of the experimental findings. We find that the anisotropy
+constants, which are the drivers behind the observed behaviour, exhibit a
+pronounced temperature dependence. This explains the differences in the
+behaviour observed at high temperatures (above T = 18 K), where the cubic
+anisotropy is weak, and at low temperatures (below T = 18 K), where a strong
+cubic anisotropy induces an abrupt appearance of the tilted spirals out of the
+conical state and enhances the stability of skyrmions.",2307.09539v1
+2023-07-19,Unraveling Cosmological Anisotropies within Stochastic Gravitational Wave Backgrounds,"Identifying the anisotropies in a cosmologically sourced stochastic
+gravitational wave background (SGWB) would be of significance in shedding light
+on the nature of primordial inhomogeneities. For example, if SGWB carries
+isocurvature fluctuations, it would provide evidence for a multi-field
+inflationary origin of these inhomogeneities. However, this is challenging in
+practice due to finite detector sensitivity and also the presence of the
+astrophysical foregrounds that can compete with the cosmological signal. In
+this work, we explore the prospects for measuring cosmological SGWB
+anisotropies in the presence of an astrophysical counterpart and detector
+noise. To illustrate the main idea, we perform a Fisher analysis using a
+well-motivated cosmological SGWB template corresponding to a first order phase
+transition, and an astrophysical SGWB template corresponding to extra-galactic
+binary mergers, and compute the uncertainty with which various parameters
+characterizing the isotropic and anisotropic components can be extracted. We
+also discuss some subtleties and caveats involving shot noise in the
+astrophysical foreground. Overall, we show that upcoming experiments, e.g.,
+LISA, Taiji, Einstein Telescope, Cosmic Explorer, and BBO, can all be effective
+in discovering plausible anisotropic cosmological SGWBs.",2307.10360v1
+2023-07-26,Highly Tunable Perpendicular Magnetic Anisotropy and Anisotropic Magnetoresistance in Ru-doped La0.67Sr0.33MnO3 Epitaxial Films,"As a prototypical half-metallic ferromagnet, La0.67Sr0.33MnO3 (LSMO) has been
+extensively studied due to its versatile physical properties and great
+potential in spintronic applications. However, the weak perpendicular magnetic
+anisotropy (PMA) limits the controllability and detection of magnetism in LSMO,
+thus hindering the realization of oxide-based spintronic devices with low
+energy consumption and high integration level. Motivated by this challenge, we
+develop an experimental approach to enhance the PMA of LSMO epitaxial films. By
+cooperatively introducing 4d Ru doping and a moderate compressive strain, the
+maximum uniaxial magnetic anisotropy in Ru-doped LSMO can reach 3.0 to 1E5 J/m3
+at 10 K. Furthermore, we find a significant anisotropic magnetoresistance
+effect in these Ru-doped LSMO films, which is dominated by the strong PMA. Our
+findings offer an effective pathway to harness and detect the orientations of
+magnetic moments in LSMO films, thus promoting the feasibility of oxide-based
+spintronic devices, such as spin valves and magnetic tunnel junctions.",2307.13881v1
+2023-07-28,Field-Free Switching in Symmetry Breaking Multilayers: The Critical Role of Interlayer Chiral Exchange,"It is crucial to realize field-free, deterministic, current-induced switching
+in spin-orbit torque magnetic random-access memory (SOT-MRAM) with
+perpendicular magnetic anisotropy (PMA). A tentative solution has emerged
+recently, which employs the interlayer chiral exchange coupling or the
+interlayer Dzyaloshinskii-Moriya interaction (i-DMI) to achieve symmetry
+breaking. We hereby investigate the interlayer DMI in a Pt/Co multilayer system
+with orthogonally magnetized layers, using repeatedly stacked [Pt/Co]n
+structure with PMA, and a thick Co layer with in-plane magnetic anisotropy
+(IMA). We clarify the origin and the direction of such symmetry breaking with
+relation to the i-DMI effective field, and show a decreasing trend of the said
+effective field magnitude to the stacking number (n). By comparing the
+current-induced field-free switching behavior for both PMA and IMA layers, we
+confirm the dominating role of i-DMI in such field-free switching, excluding
+other possible mechanisms such as tilted-anisotropy and unconventional spin
+currents that may have arisen from the symmetry breaking.",2307.15258v2
+2023-07-31,Cosmological First-Order Vacuum Phase Transitions in an Expanding Anisotropic Universe,"We examine the anisotropy originated from a first-order vacuum phase
+transitions through three-dimensional numerical simulations. We apply Bianchi
+Type-I metric to our model that has one scalar field minimally coupled to the
+gravity. We calculate the time evolution of the energy density for the shear
+scalar and the directional Hubble parameters as well as the power spectra for
+the scalar field and the gravitational radiation although there are a number of
+caveats for the tensor perturbations in Bianchi Type-I universe. We run
+simulations with different mass scales of the scalar field, therefore, in
+addition to investigation of anisotropy via the shear scalar, we also determine
+at which mass scale the phase transition completes successfully, hence,
+neglecting the expansion of the Universe does not significantly affect the
+results. Finally, we showed that such an event may contribute to the total
+anisotropy depending on the mass scale of the scalar field and the initial
+population of nucleated bubbles.",2307.16458v1
+2023-08-04,Anisotropy of the spin Hall effect in a Dirac ferromagnet,"We study the intrinsic spin Hall effect of a Dirac Hamiltonian system with
+ferromagnetic exchange coupling, a minimal model combining relativistic
+spin-orbit interaction and ferromagnetism. The energy bands of the Dirac
+Hamiltonian are split after introducing a Stoner-type ferromagnetic ordering
+which breaks the spherical symmetry of pristine Dirac model. The totally
+antisymmetric spin Hall conductivity (SHC) tensor becomes axially anisotropic
+along the direction of external electric field. Interestingly, the anisotropy
+does not vanish in the asymptotic limit of zero magnetization. We show that the
+ferromagnetic ordering breaks the spin degeneracy of the eigenfunctions and
+modifies the selection rules of the interband transitions for the intrinsic
+spin Hall effect. The difference in the selection rule between the pristine and
+the ferromagnetic Dirac phases causes the anisotropy of the SHC, resulting in a
+discontinuity of the SHC as the magnetization, directed orthogonal to the
+electric field, is reduced to zero in the ferromagnetic Dirac phase and enters
+the pristine Dirac phase.",2308.02336v1
+2023-08-22,Theory of defect-induced crystal field perturbations in rare earth magnets,"We present a theory describing the single-ion anisotropy of rare earth (RE)
+magnets in the presence of point defects. Taking the RE-lean 1:12 magnet class
+as a prototype, we use first-principles calculations to show how the
+introduction of Ti substitutions into SmFe$_{12}$ perturbs the crystal field,
+generating new coefficients due to the lower symmetry of the RE environment. We
+then demonstrate that these perturbations can be described extremely
+efficiently using a screened point charge model. We provide analytical
+expressions for the anisotropy energy which can be straightforwardly
+implemented in atomistic spin dynamics simulations, meaning that such
+simulations can be carried out for an arbitrary arrangement of point defects.
+The significant crystal field perturbations calculated here demonstrate that a
+sample which is single-phase from a structural point of view can nonetheless
+have a dramatically varying anisotropy profile at the atomistic level if there
+is compositional disorder, which may influence localized magnetic objects like
+domain walls or skyrmions.",2308.11303v1
+2023-09-04,Anisotropic Seebeck coefficient of $\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$ in the incoherent regime,"Intuitive entropic interpretations of the thermoelectric effect in metals
+predict an isotropic Seebeck coefficient at high temperatures in the incoherent
+regime even in anisotropic metals since entropy is not directional.
+$\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$ is an enigmatic material known for a
+well characterised anisotropic normal state and unconventional
+superconductivity. Recent ab-initio transport calculations of
+$\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$ that include the effect of strong
+electronic correlations predicted an enhanced high-temperature anisotropy of
+the Seebeck coefficient at temperatures above 300 K, but experimental evidence
+is missing. From measurements on clean $\mathrm{Sr}_2\mathrm{Ru}\mathrm{O}_4$
+single crystals along both crystallographic directions, we find that the
+Seebeck coefficient becomes increasingly isotropic upon heating towards room
+temperature as generally expected. Above 300 K, however, $S$ acquires a new
+anisotropy which rises up to the highest temperatures measured (750 K), in
+qualitative agreement with calculations. This is a challenge to entropic
+interpretations and highlights the lack of an intuitive framework to understand
+the anisotropy of thermopower at high temperatures.",2309.01403v1
+2023-09-04,On the anisotropies of the cosmological gravitational-wave background from pulsar timing array observations,"Significant evidence for a stochastic gravitational-wave background has
+recently been reported by several Pulsar Timing Array observations. These
+studies have shown that, in addition to astrophysical explanations based on
+supermassive black hole binaries (SMBHBs), cosmological origins are considered
+equally important sources for these signals. To further explore these
+cosmological sources, in this study, we discuss the anisotropies in the
+cosmological gravitational wave background (CGWB) in a model-independent way.
+Taking the North American Nanohertz Observatory for Gravitational Waves
+(NANOGrav) 15-year dataset as a benchmark, we estimate the angular power
+spectra of the CGWB and their cross-correlations with cosmic microwave
+background (CMB) fluctuations and weak gravitational lensing. We find that the
+NANOGrav 15-year data implies suppressed Sachs-Wolf (SW) effects in the CGBW
+spectrum, leading to a marginally negative cross-correlation with the CMB at
+large scales. This procedure is applicable to signals introduced by different
+early universe processes and is potentially useful for identifying unique
+features about anisotropies of CGWB from future space-based interferometers and
+astrometric measurements.",2309.01643v2
+2023-09-07,Nonreciprocal phonon dichroism induced by Fermi pocket anisotropy in two-dimensional Dirac materials,"Electrons in two-dimensional (2D) Dirac materials carry local band geometric
+quantities, such as the Berry curvature and orbital magnetic moments, which,
+combined with electron-phonon coupling, may affect the phonon dynamics in an
+unusual way. Here, we propose intrinsic nonreciprocal linear and circular
+phonon dichroism in magnetic 2D Dirac materials, which originate from nonlocal
+band geometric quantities of electrons and reduce to pure Fermi-surface
+properties for acoustic phonons. We find that to acquire the nonreciprocity,
+the Fermi pocket anisotropy rather than the chirality of electrons is crucial.
+Two possible mechanisms of Fermi pocket anisotropy are suggested: (i) trigonal
+warping and out-of-plane magnetization or (ii) Rashba spin-orbit interaction
+and in-plane magnetization. As a concrete example, we predict appreciable and
+tunable nonreciprocal phonon dichroism in 2H-MoTe 2 on a EuO substrate. Our
+finding points to a different route towards electrical control of phonon
+nonreciprocity for acoustoelectronics applications based on 2D quantum
+materials.",2309.03540v1
+2023-09-11,Anisotropic diffusion of radiation-induced self-interstitial clusters in HCP zirconium: a molecular dynamics and rate-theory assessment,"Under irradiation, Zr and Zr alloys undergo growth in the absence of applied
+stress. This phenomenon is thought to be associated with the anisotropy of
+diffusion of either or both radiation-induced point defects and defect
+clusters. In this work, molecular dynamic simulations are used to study the
+anisotropy of diffusion of self-interstitial atom clusters. Both
+near-equilibrium clusters generated by aggregation of self-interstitial atoms
+and cascade-induced clusters were considered. The cascade-induced clusters
+display more anisotropy than their counterparts produced by aggregation. In
+addition to 1-dimensional diffusing clusters, 2-dimensional diffusing clusters
+were observed. Using our molecular dynamic simulations, the input parameters
+for the ""self-interstitial atom cluster bias"" rate-theory model were estimated.
+The radiation-induced growth strains predicted using this model are largely
+consistent with experiments, but are highly sensitive to the choice of
+interatomic interaction potential.",2309.05781v1
+2023-09-16,Anisotropy of Antiferromagnetic Domains in a Spin-orbit Mott Insulator,"The temperature-dependent behavior of magnetic domains plays an essential
+role in the magnetic properties of materials, leading to widespread
+applications. However, experimental methods to access the three-dimensional
+(3D) magnetic domain structures are very limited, especially for
+antiferromagnets. Over the past decades, the spin-orbit Mott insulator iridate
+$Sr_2IrO_4$ has attracted particular attention because of its interesting
+magnetic structure and analogy to superconducting cuprates. Here, we apply
+resonant x-ray magnetic Bragg coherent diffraction imaging to track the
+real-space 3D evolution of antiferromagnetic ordering inside a $Sr_2IrO_4$
+single crystal as a function of temperature, finding that the antiferromagnetic
+domain shows anisotropic changes. The anisotropy of the domain shape reveals
+the underlying anisotropy of the antiferromagnetic coupling strength within
+$Sr_2IrO_4$. These results demonstrate the high potential significance of 3D
+domain imaging in magnetism research.",2309.09091v1
+2023-09-20,A comparative study on maximum mass and radius of compact star from Heintzmann geometry and TOV approach,"In this article a class of anisotropic compact star is analysed in Heintzmann
+geometry. We have introduced the pressure anisotropy parameter ($\alpha$) and
+solved Einstein field equations to obtain stellar model. We have considered
+$g_{tt}$ component as proposed by Heintzmann and by solving Einstein field
+equation, the $g_{rr}$ component is evaluated in presence of pressure
+anisotropy. It is noted that for isotropic star ($\alpha=0$), the maximum mass
+lies within the range $1.87-3.04~ M_{\odot}$ for radii ranges between $8-13$
+Km. For anisotropic compact stars maximum mass increases with $\alpha$ and lies
+within the range $1.99-3.23~ M_{\odot}$ for anisotropy parameter $\alpha=0.5$.
+The physical viability of the model is examined by applying our model to study
+the properties of few known compact objects. It is noted that all the stability
+conditions are fulfilled in the proposed model. It is interesting to note that
+maximum mass calculated from our model and from solving TOV equation are
+approximately same and also the predicted radius of few newly observed pulsars
+and companion star of GW events GW 190814 and GW 170817 from our model comply
+with the estimated value of radius from observation.",2309.11468v1
+2023-09-21,The influence of film thickness and uniaxial anisotropy on in-plane skyrmions: Numerical investigations of the phase space of chiral magnets,"The equilibrium phase space of magnetic textures in thin-films of cubic
+chiral ferromagnets, including skyrmions, is explored as a function of in-plane
+magnetic field strength, film thickness and uniaxial anisotropy. The interplay
+between these system parameters is found to give rise to a phase space with a
+rich structure, distinct from that of the nano-stripes that have been
+previously studied. For certain values of the anisotropy, the range of
+thicknesses supporting in-plane skyrmions and/or helicoids with an out-of-plane
+propagation vector is found to be disconnected, suggesting a possible direction
+for future experiments. We explain how this interesting phase space topology
+arises due to the geometric confinement of the thin-film system, and identify
+the optimal parameter ranges for future explorations of novel magnetic textures
+such as the oblique spiral phase.",2309.12419v1
+2023-10-04,Anisotropy of magnetized quark matter,"Strong transient magnetic fields are generated in non-central relativistic
+heavy-ion collisions. These fields induce anisotropy within the strongly
+interacting medium that, in principle, can affect the thermodynamic properties
+of the medium. We use the Polaykov loop extended Nambu Jona-Lasinio (PNJL)
+model to study the quark matter subjected to an external magnetic field at
+vanishing baryon chemical potential. We have estimated the degree of anisotropy
+in the speed of sound and isothermal compressibility within the magnetized
+quark matter as a function of temperature and magnetic field. This study helps
+us to understand the extent of directionality generated in the initial stages
+of non-central collisions while giving us useful information about the system.",2310.02711v1
+2023-10-06,Rock anisotropy promotes hydraulic fracture containment at depth,"We report laboratory experiments and numerical simulations demonstrating that
+the anisotropic characteristics of rocks play a major role in the elongation of
+hydraulic fractures propagating in a plane perpendicular to bedding. Transverse
+anisotropy leads to larger hydraulic fracture extension in the
+parallel-to-bedding/divider direction compared to the
+perpendicular-to-bedding/arrester direction. This directly promotes vertical
+containment of hydraulic fractures in most sedimentary basins worldwide even in
+the absence of any favorable in-situ stress contrasts or other material
+heterogeneities. More importantly, the ratio of the energy dissipated in fluid
+viscous flow in the fracture to the energy dissipated in the creation of new
+surfaces is found to play a critical role on fracture elongation, with
+fracture-energy dominated hydraulic fractures being the most elongated while
+the viscous dominated ones remain more circular. These results open the door to
+a better engineering and control of hydraulic fractures containment at depth in
+view of the competition between material anisotropy and injection parameters
+(fluid viscosity and rate of injection).",2310.04374v1
+2023-10-09,Spatial asymmetry of optically excited spin waves in anisotropic ferromagnetic film,"We analytically discuss and micromagnetically prove the ways to tune the
+spatial asymmetry of the initial phase, amplitude, and wavevectors of
+magnetostatic waves driven by ultrafast laser excitation. We consider that the
+optical pulse heats a thin ferromagnetic metallic film and abruptly decreases
+the saturation magnetization and the parameter of uniaxial anisotropy. The two
+corresponding terms of laser-induced torque have different azimuthal
+symmetries, with the 4-fold symmetry of the demagnetization-related term, and
+the isotropic distribution of the anisotropy-related term. As a result, the
+initial phase and amplitude of excited magnetostatic waves have a non-trivial
+azimuthal distribution tunable with the angle between the external magnetic
+field and anisotropy axis, and the laser spot diameter. Moreover, the variation
+of these parameters tunes the distribution of wavevectors, resulting in
+additional asymmetry between the spectral components of the waves propagating
+in different directions.",2310.05895v1
+2023-10-12,Effective potential engineering by emergent anisotropy in a tunable open-access microcavity,"Photonic spin-orbit (SO) coupling is an important physical mechanism leading
+to numerous interesting phenomena in the systems of microcavity photons and
+exciton-polaritons. We report the effect of SO coupling in a tunable
+open-access microcavity embedded with anisotropic active media. The SO coupling
+associated with the TE-TM splitting results in an emergent anisotropy, which
+further leads to fine energy splittings allowing clear observation of the full
+set of eigenstates, in sharp contrast with the isotropic situation which leads
+to the isotropic eigenstates of spin vortices. We show that the photonic
+potential can be engineered by playing with the relation between the emergent
+anisotropy and the cavity ellipticity. All the experimental results are well
+reproduced by the degenerate perturbation theory. Our results constitute a
+significant extension to the research field of microcavity spinoptronics, with
+potential applications in polarization control and optical property measurement
+of photonic devices and materials.",2310.08024v1
+2023-10-18,Giant Spin Transport Anisotropy in Magnetic Topological Insulators,"We report on exceptionally long spin transport and giant spin lifetime
+anisotropy in the gapped surface states of three-dimensional (3D) magnetic
+topological insulators (MTIs). We examine the properties of these states using
+the Fu-Kane-Mele Hamiltonian in presence of a magnetic exchange field. The
+corresponding spin textures of surface states, which are well reproduced by an
+effective two-band model, hint at a considerable enhancement of the lifetime of
+out-of-plane spins compared to in-plane spins. This is confirmed by large-scale
+spin transport simulations for 3D MTIs with disorder. The energy dependence of
+the spin lifetime anisotropy arises directly from the nontrivial spin texture
+of the surface states, and is correlated with the onset of the quantum
+anomalous Hall phase. Our findings suggest novel spin filtering capabilities of
+the gapped surface MTI states, which could be explored by Hanle spin precession
+measurements.",2310.12377v1
+2023-10-24,Strain-driven switching between antiferromagnetic states in frustrated antiferromagnet UO2 probed by exchange bias effect,"Frustrated antiferromagnets offer a captivating platform to study the
+intricate relationship of magnetic interactions, geometric constraints, and
+emergent phenomena. By controlling spin orientations, these materials can be
+tailored for applications in spintronics and quantum information processing.
+The research focuses on the interplay of magnetic and exchange anisotropy
+effects in artificial heterostructures based on a canonical frustrated
+antiferromagnet, UO2. The potential to manipulate the spin directions in this
+material and switch between distinct antiferromagnetic states is investigated
+using substrate-induced strain. The phenomenon is probed using exchange bias
+(EB) effects in stoichiometric UO2/Fe3O4 bilayers. By employing many-body
+first-principles calculations magnetic configurations in the UO2 layers are
+identified. Even a minor tetragonal distortion triggers a transition between
+antiferromagnetic states of different symmetries, driven by a robust alteration
+of single-ion anisotropy due to the distortion. Consequently, this change
+influences the arrangement of magnetic moments at the UO2/Fe3O4 interface,
+affecting the magnitude of exchange bias. The findings showcase how epitaxial
+strain can effectively manipulate the antiferromagnetic states in frustrated
+antiferromagnets by controlling single-site anisotropy.",2310.15696v1
+2023-10-31,Highly Anisotropic Elastic Properties of Suspended Black Arsenic Nanoribbons,"Anisotropy, as an exotic degree of freedom, enables us to discover the
+emergent two-dimensional (2D) layered nanomaterials with low in-plane symmetry
+and to explore their outstanding properties and promising applications. 2D
+black arsenic (b-As) with puckered structure has garnered increasing attention
+these years owing to its extreme anisotropy with respect to the electrical,
+thermal, and optical properties. However, the investigation on mechanical
+properties of 2D b-As is still lacking, despite much effort on theoretical
+simulations. Herein, we report the highly anisotropic elastic properties of
+suspended b-As nanoribbons via atomic force microscope-based nanoindentation.
+It was found that the extracted Young's modulus of b-As nanoribbons exhibits
+remarkable anisotropy, which approximates to 72.2 +- 5.4 and 44.3 +- 1.4 GPa
+along zigzag and armchair directions, respectively. The anisotropic ratio
+reaches up to ~ 1.6. We expect that these results could lay a solid foundation
+for the potential applications of 2D anisotropic nanomaterials in the
+next-generation nanomechanics and optoelectronics.",2310.20164v1
+2023-11-07,Classical spin models and basic magnetic interactions on 1/1-approximant crystals,"We study classical spin models on the 1/1 Tsai-type approximant lattice using
+Monte Carlo and mean-field methods. Our aim is to understand whether the phase
+diagram differences between Gd- and Tb-based approximants can be attributed to
+anisotropy induced by the crystal-electric field. To address this question, we
+treat Gd ions as Heisenberg spins and Tb ions as Ising spins. Additionally, we
+consider the presence of the RKKY interaction to replicate the experimentally
+observed correlation between magnetic properties and electron concentration.
+Surprisingly, our findings show that the transition between ferromagnetic and
+antiferromagnetic order remains unaltered by the anisotropy, even when
+accounting for the dipole interaction. We conclude that a more comprehensive
+model, extending beyond the free-electron gas RKKY interaction, is likely
+required to fully understand the distinctions between Gd- and Tb-based
+approximants. Our work represents a systematic exploration of the impact of
+anisotropy on the ground-state properties of classical spin models in
+quasicrystal approximants.",2311.03781v2
+2023-11-07,Structural Transition and Magnetic Anisotropy in $α$-RuCl$_{3}$,"We report X-ray diffraction and magnetic susceptibility studies of the
+structural phase transition in $\alpha$-RuCl$_{3}$. By utilizing a single
+crystal sample with predominantly single twin domain, we show that
+$\alpha$-RuCl$_{3}$ goes from high-temperature C2/m structure to a rhombohedral
+structure with R$\bar{3}$ symmetry at low temperature. While the defining
+feature of the structural transition is changing the stacking direction from
+the monoclinic a-axis to the b-axis, bond-anisotropy disappears when the
+structural change occurs, indicating that the local $C_3$ symmetry is restored
+within the honeycomb layer. The symmetry change is corroborated by the
+vanishing magnetic anisotropy in the low-temperature structure. Our study
+demonstrates that magnetic interaction is extremely sensitive to structural
+details in $\alpha$-RuCl$_{3}$, which could explain the sample dependence found
+in this material.",2311.04000v1
+2023-11-08,Giant anisotropy and Casimir phenomena: the case of carbon nanotube metasurfaces,"The Casimir interaction and torque are related phenomena originating from the
+exchange of electromagnetic excitations between objects. While the Casimir
+force exists between any types of objects, the materials or geometrical
+anisotropy drives the emergence of the Casimir torque. Here both phenomena are
+studied theoretically between dielectric films with immersed parallel single
+wall carbon nanotubes in the dilute limit with their chirality and collective
+electronic and optical response properties taken into account. It is found that
+the Casimir interaction is dominated by thermal fluctuations at sub-micron
+separations, while the torque is primarily determined by quantum mechanical
+effects. This peculiar quantum vs. thermal separation is attributed to the
+strong influence of reduced dimensionality and inherent anisotropy of the
+materials. Our study suggests that nanostructured anisotropic materials can
+serve as novel platforms to uncover new functionalities in ubiquitous Casimir
+phenomena.",2311.05001v1
+2023-11-13,Translational symmetry broken magnetization plateau of the S=1 antiferromagnetic Heisenberg chain with competing anisotropies,"We investigate the S=1 antiferromagnetic quantum spin chain with the exchange
+and single-ion anisotropies in a magnetic field, using the numerical exact
+diagonalization of finite-size clusters, the level spectroscopy analysis, and
+the density matrix renormalization group (DMRG) method. It is found that a
+translational symmetry broken magnetization plateau possibly appears at the
+half of the saturation magnetization, when the anisotropies compete with each
+other. The level spectroscopy analysis gives the phase diagram at half the
+saturation magnetization. The DMRG calculation presents the magnetization
+curves for some typical parameters and clarifies the spin structure in the
+plateau phase.",2311.07123v1
+2023-11-13,"Nematic superconductivity from selective orbital pairing in Ba(Fe1-xMx)2As2 (M = Co, Ni) single crystals","We use transport measurements to determine the in-plane anisotropy of the
+upper critical field Hc2 in detwinned superconducting Ba(Fe1-xMx)2As2 (M = Co,
+Ni) single crystals. In previous measurements on twinned single crystals, the
+charge carrier doping dependence (x) of the upper critical field anisotropy for
+fields along the inter-planar (c-axis) and in-plane field directions was found
+to increase in the overdoped regime. For underdoped samples, which exhibit a
+spin nematic phase below the tetragonal to orthorhombic structural transition
+temperature Ts , we find that Hc2 along the a-axis is considerably lower than
+that along the b-axis. The upper critical field anisotropy disappears in the
+over-doped regime when the system becomes tetragonal. By combining these
+results with inelastic neutron scattering studies of spin excitations, and
+angle-resolved photoemission spectroscopy, we conclude that superconductivity
+in under-doped iron pnictides is orbital selective - with a dominant
+contribution from electrons with the dyz orbital character and being intimately
+associated with spin excitations.",2311.07697v1
+2023-11-19,Multicritical dissipative phase transitions in the anisotropic open quantum Rabi model,"We investigate the nonequilibrium steady state of the anisotropic open
+quantum Rabi model, which exhibits first-order and second-order dissipative
+phase transitions upon varying the degree of anisotropy between the coupling
+strengths of rotating and counterrotating terms. Using both semiclassical and
+quantum approaches, we find a rich phase diagram resulting from the interplay
+between the anisotropy and the dissipation. First, there exists a bistable
+phase where both the normal and superradiant phases are stable. Second, there
+are multicritical points where the phase boundaries for the first- and
+second-order phase transitions meet. We show that a new set of critical
+exponents governs the scaling of the multicritical points. Finally, we discuss
+the feasibility of observing the multicritical transitions and bistability
+using a pair of trapped ions where the anisotropy can be tuned by the
+controlling the intensity of the Raman transitions. Our study enlarges the
+scope of critical phenomena that may occur in finite-component quantum systems,
+which could be useful for the applications in the critical quantum sensing.",2311.11346v1
+2023-11-24,Physics-Informed Tensor Basis Neural Network for Turbulence Closure Modeling,"Despite the increasing availability of high-performance computational
+resources, Reynolds-Averaged Navier-Stokes (RANS) simulations remain the
+workhorse for the analysis of turbulent flows in real-world applications.
+Linear eddy viscosity models (LEVM), the most commonly employed model type,
+cannot accurately predict complex states of turbulence. This work combines a
+deep-neural-network-based, nonlinear eddy viscosity model with turbulence
+realizability constraints as an inductive bias in order to yield improved
+predictions of the anisotropy tensor. Using visualizations based on the
+barycentric map, we show that the proposed machine learning method's anisotropy
+tensor predictions offer a significant improvement over all LEVMs in
+traditionally challenging cases with surface curvature and flow separation.
+However, this improved anisotropy tensor does not, in general, yield improved
+mean-velocity and pressure field predictions in comparison with the
+best-performing LEVM.",2311.14576v1
+2023-11-30,Dynamic Phase Transition in 2D Ising Systems: Effect of Anisotropy and Defects,"We investigate the dynamic phase transition in two-dimensional Ising models
+whose equilibrium characteristics are influenced by either anisotropic
+interactions or quenched defects. The presence of anisotropy reduces the
+dynamical critical temperature, leading to the expected result that the
+critical temperature approaches zero in the full-anisotropy limit. We show that
+a comprehensive understanding of the dynamic behavior of systems with quenched
+defects requires a generalized definition of the dynamic order parameter. By
+doing so, we demonstrate that the inclusion of quenched defects lowers the
+dynamic critical temperature as well, with a linear trend across the range of
+defect fractions considered. We also explore if and how it is possible to
+predict the dynamic behavior of specific magnetic systems with quenched
+randomness. Various geometric quantities, such as a defect potential index, the
+defect dipole moment, and the properties of the defect Delaunay triangulation,
+prove useful for this purpose.",2312.00153v2
+2023-12-04,Real-Space Visualization of Frequency-Dependent Anisotropy of Atomic Vibrations,"The underlying dielectric properties of materials, intertwined with
+intriguing phenomena such as topological polariton modes and anisotropic
+thermal conductivities, stem from the anisotropy in atomic vibrations.
+Conventionally, X-ray diffraction techniques have been employed to estimate
+thermal ellipsoids of distinct elements, albeit lacking the desired spatial and
+energy resolutions. Here we introduce a novel approach utilizing the dark-field
+monochromated electron energy-loss spectroscopy for momentum-selective
+vibrational spectroscopy, enabling the cartographic delineation of variations
+of phonon polarization vectors. By applying this technique to centrosymmetric
+cubic-phase strontium titanate, we successfully discern two types of oxygen
+atoms exhibiting contrasting vibrational anisotropies below and above 60 meV
+due to their frequency-linked thermal ellipsoids. This method establishes a new
+pathway to visualize phonon eigenvectors at specific crystalline sites for
+diverse elements, thus delving into uncharted realms of dielectric, optical,
+and thermal property investigations with unprecedented spatial resolutions.",2312.01694v1
+2023-12-05,Gate-tunable graphene Josephson diode effect due to magnetochiral anisotropy,"Usually the magnetochiral anisotropy related Josephson diode effect is
+assumed to be based on conventional two-dimensional electron gas, such as the
+InAs quantum well. Here we propose a graphene-based Josephson junction as a
+broadly gate-tunable platform for achieving nonreciprocal supercurrent within
+the context of magnetochiral anisotropy. We show that the resulting
+nonreciprocal supercurrents will exhibit a sign reversal when the graphene
+switches from $n$-type doping to $p$-type doping. Particularly, the magnitude
+of the nonreciprocity is highly sensitive to the electrostatic doping level of
+graphene, enabling gate control of the diode efficiency from zero up to
+approximately $40\%$. This giant gate-tunability stems from the chiral nature
+of the pseudo-relativistic carriers in grapehe, allowing the graphene Josephson
+diode emerges as a promising element for advanced superconducting circuits and
+computation devices. Moreover, we have also obtained the so-called $0-\pi$-like
+phase transitions in the current-phase relation, in coincidence with recent
+experimental finding.",2312.02692v1
+2023-12-05,Miniaturized Double-Wing Delta-E Effect Sensors,"Magnetoelastic composites are integral elements of sensors and actuators
+utilizing magnetostriction for their functionality. Their sensitivity typically
+scales with the saturation magnetostriction and inversely with magnetic
+anisotropy. However, this makes the devices prone to minuscule residual
+anisotropic stress from the fabrication process, impairing their performance
+and reproducibility, hence limiting their suitability for arrays. This study
+presents a shadow mask deposition technology combined with a free-free
+magnetoelectric microresonator design intended to minimize residual stress and
+inhomogeneity in the magnetoelastic layer. Resonators are experimentally and
+theoretically analyzed regarding local stress anisotropy, magnetic anisotropy,
+and the {\Delta}E effect in several resonance modes. Further, the sensitivity
+is analyzed in the example of {\Delta}E-effect sensors. The results demonstrate
+a device-to-device variation of the resonance frequency < 0.2 % with
+sensitivities comparable with macroscopic {\Delta}E-effect sensors. The
+reproducibility is drastically improved over previous magnetoelastic device
+arrays. This development marks a step forward in the reproducibility and
+homogeneity of magnetoelastic resonators and contributes to the feasibility of
+large-scale, integrated sensor arrays.",2312.02903v1
+2023-12-08,Dipolar coupled core-shell perpendicular shape anisotropy MTJ with enhanced write speed and reduced cross-talk,"The concept of Perpendicular Shape-Anisotropy Spin-Transfer-Torque Magnetic
+Random-Access Memory tackles the downsize scalability limit of conventional
+ultrathin magnetic tunnel junctions (MTJ) below sub-20 nm technological nodes.
+This concept uses a thicker storage layer with a vertical aspect ratio,
+enhancing the thermal stability factor thanks to the favorable contribution of
+the shape anisotropy. However, the increased aspect ratio comes with an
+increase in switching time under applied voltage and the cross-over to
+non-uniform reversal mechanism at higher aspect ratio, limiting the gain in
+scalability. Additionally, the larger volume of the magnetic cell significantly
+increases the stray field acting on the neighboring devices compared to thin
+MTJs. In this work, we propose the use of a dipolar-coupled core-shell system
+as a storage layer. This improves both bottlenecks, as predicted by
+micromagnetic simulations for magnetisation reversal, and a macrospin model to
+estimate the stray field in a dense array.",2312.05245v1
+2023-12-12,Constraining ultralight bosons in dwarf spheroidal galaxies with a radially varying anisotropy,"Axions, and axion-like particles, have come back into fashion in the last
+decades as a possible solution to the galactic-scale crisis suffered by the
+cold dark matter model. In the framework of the wave Dark Matter model, we have
+carried out a Jeans Analysis on eight dwarf spheroidal galaxies that are
+orbiting around the Milky Way, and we have constrained the boson mass.
+Differently to a previous analysis, we adopted an anisotropy parameter that
+varies with the distance from the centre of the galaxy to assess whether this
+assumption would help to resolve, or at least alleviate, the well-known tension
+with the value of the boson mass favoured by the cosmological analysis. Our
+results indicate that, differently to what happens in ultra-faint dwarf
+galaxies, such a tension cannot be lifted introducing a variable anisotropy
+parameter, leaving as a possible solution the existence of additional axion or
+axion-like particles with higher masses as naturally predicted in the Axiverse.",2312.07217v1
+2023-12-13,Highly anisotropic lattices for Yang-Mills theory,"In this conference proceeding, we investigate the physical anisotropy in
+terms of the temporal and spatial lattice spacings in relation to the bare
+parameters of SU(2) pure gauge theory using Wilson gradient flow. Anisotropic
+lattices have a wide range of applications, from thermodynamic calculations in
+QCD to very recent real-time simulations using the complex Langevin method. We
+find an almost linear relationship between the bare and renormalized
+anisotropy. Using a parametrization that includes nonlinear effects and was
+earlier proposed for SU(3) theory, we obtain a good description of the coupling
+dependence of the anisotropy with only two fitting parameters. Our observation
+of an approximately linear relationship and this parametrization should
+strongly reduce the computational effort of anisotropic lattice calculations in
+the future.",2312.08172v1
+2024-01-18,Exploring the anisotropic HISQ (aHISQ) action,"The fate of heavy quarkonia states in quark-gluon plasma is encoded in the
+temperature dependence of their spectral functions. Reconstruction of spectral
+functions from Euclidean lattice correlators is an ill-posed problem. Despite a
+variety of techniques developed recently, many questions remain unresolved. It
+is known that the situation may be improved using anisotropic ensembles that
+provide finer resolution in the temporal direction. To date, the effort focused
+on Wilson fermions. We report on our first study with anisotropic improved
+staggered quarks. To compute the spectrum of the anisotropic Highly Improved
+Staggered Quarks (aHISQ) we generated a library of anisotropic pure gauge
+ensembles. We discuss the gauge anisotropy tuning that is performed with the
+Wilson and Symanzik gradient flow, as well as tuning of the strange quark mass
+and quark anisotropy with aHISQ, using spectrum measurements on quenched
+ensembles. Finally, we discuss the impact of anisotropy on pion taste
+splittings for aHISQ.",2401.10049v1
+2024-01-28,Constraints on an Anisotropic Universe,"We analyze the possibility of global anisotropy of the universe. We consider
+an altered FLRW metric in which there are different scale factors along the 3
+different axes of space. We construct the corresponding altered Friedmann
+equations. We show that any initial anisotropies decrease into the future. At
+late times, the difference in Hubble parameters changes as $1/\sqrt{t}$ in a
+radiation dominated era and as $1/t$ in a matter dominated era. We use
+constraints from Big Bang Nucleosynthesis and the Cosmic Microwave Background
+to constrain the level of anisotropies at early times. We also examine how the
+approach back in time to the singularity is radically altered; happening much
+more abruptly, as a function of density, in an anisotropic universe. We also
+mention improved bounds that can arise from measurements of primordial
+gravitons, WIMPs, and neutrinos.",2401.15782v2
+2024-02-29,Viscoelastic response and anisotropic hydrodynamics in Weyl semimetals,"We study viscoelastic response in Weyl semimetals with broken time-reversal
+symmetry. Topology and anisotropy of the Fermi surface are manifested in the
+viscoelasticity tensor of the electron fluid. In the dynamic (inter-band) part
+of this tensor, the anisotropy leads to a qualitatively different, compared to
+isotropic models, scaling with frequency and the Fermi energy. While components
+of the viscosity tensor determined by the Fermi surface properties agree in the
+Kubo and kinetic formalisms, the latter misses the anomalous Hall viscosity
+determined by filled states below the Fermi surface. The anisotropy of the
+dispersion relation is also manifested in the acceleration and relaxation terms
+of the hydrodynamic equations.",2402.19304v1
+2024-03-04,Elliptic anisotropy of open-charm hadron in p--Pb collisions at LHC energies from parton scatterings,"The elliptic azimuthal anisotropy coefficient ($v_{2}$) of open-charm hadron
+at midrapidity ($|\eta<1|$) was studied in p--Pb collisions at
+$\sqrt{s_{\mathrm{NN}}}=$ 8.16 TeV using a multi-phase transport model (AMPT).
+By implementing an additional heavy quark--antiquark pair production trigger in
+the AMPT, we obtained a simultaneously description of the $p_{\mathrm{T}}$
+spectrum and $v_{2}$ of $D^{0}$ meson. Then the predictions for the $v_{2}$ of
+charm hadrons including $D^{+}$, $D_{s}^{+}$ and $\Lambda_{c}^{+}$ in p--Pb
+collisions are provided for the first time. We found that the $v_{2}$ of
+open-charm hadron follows the number-of-constituent-quark (NCQ) scaling in
+high-multiplicity p--Pb collisions, and is significantly affected by the parton
+scattering process. These findings further demonstrate the importance of
+partonic degrees of freedom in small collision systems for heavy flavors, and
+provide referential value for future measurements of azimuthal anisotropy at
+the LHC energies.",2403.01677v1
+2024-03-08,Heavy quarkonium spectral function in an anisotropic background,"In this paper, we use a five-dimensional Einstein-dilaton-two-Maxwell
+holographic QCD model to investigate the dissociation effects of $J/\Psi$ and
+$\Upsilon(1S)$ states in an anisotropic medium by calculating their spectral
+functions. First, we present the holographic quarkonium masses at zero
+temperature via Physics-Informed Neural Networks. Then, at finite temperature,
+we derive the spectral functions, representing heavy vector mesons as peaks,
+and observe that with increasing anisotropy, temperature, chemical potential,
+and warp factor, the peak height diminishes while its width expands, indicating
+an accelerated dissociation process. Additionally, the results indicate the
+anisotropy induces a stronger dissociation effect in the direction parallel to
+the polarization compared to the perpendicular, revealing the anisotropy's
+directional influence.",2403.04966v3
+2024-03-09,Switching intrinsic magnetic skyrmions with controllable magnetic anisotropy in van der Waals multiferroic heterostructures,"Magnetic skyrmions, topologically nontrivial whirling spin textures at
+nanometer scales, have emerged as potential information carriers for spintronic
+devices. The ability to efficiently create and erase magnetic skyrmions is
+vital yet challenging for such applications. Based on first-principles studies,
+we find that switching between intrinsic magnetic skyrmion and high-temperature
+ferromagnetic states can be achieved in two-dimensional van der Waals (vdW)
+multiferroic heterostructure CrSeI/In2Te3 by reversing the ferroelectric
+polarization of In2Te3. The core mechanism of this switching is traced to the
+controllable magnetic anisotropy of CrSeI influenced by the ferroelectric
+polarization of In2Te3. We propose a useful descriptor linking the presence of
+magnetic skyrmions to magnetic parameters, and validate this connection through
+studies of a variety of similar vdW multiferroic heterostructures. Our work
+demonstrates that manipulating magnetic skyrmions via tunable magnetic
+anisotropies in vdW multiferroic heterostructures represents a highly promising
+and energy-efficient strategy for future development of spintronics.",2403.05747v1
+2024-03-12,Bending Mechanics of Biomimetic Scale Plates,"We develop the fundamentals of nonlinear and anisotropic bending behavior of
+biomimetic scale plates using a combination of analytical modeling, finite
+element (FE) computations, and motivational experiments. The analytical
+architecture-property relationships are derived for both synclastic and
+anticlastic curvatures. The results show that, as the scales engage, both
+synclastic and anticlastic deformations show non-linear scale contact
+kinematics and cross-curvature sensitivity of moments resulting in strong
+curvature-dependent elastic nonlinearity and emergent anisotropy. The
+anisotropy of bending rigidities and their evolution with curvature are
+affected by both the direction and magnitude of bending as well as scale
+geometry parameters, and their distribution on the substrate. Like earlier
+beam-like substrates, kinematic locked states were found to occur; however,
+their existence and evolution are also strongly determined by scale geometry
+and imposed cross-curvatures. This validated model helps us to quantify bending
+response, locking behavior, and their geometric dependence, paving the way for
+a deeper understanding of the nature of nonlinearity and anisotropy of these
+systems.",2403.08026v1
+2024-03-15,Agile and Safe Trajectory Planning for Quadruped Navigation with Motion Anisotropy Awareness,"Quadruped robots demonstrate robust and agile movements in various terrains;
+however, their navigation autonomy is still insufficient. One of the challenges
+is that the motion capabilities of the quadruped robot are anisotropic along
+different directions, which significantly affects the safety of quadruped robot
+navigation. This paper proposes a navigation framework that takes into account
+the motion anisotropy of quadruped robots including kinodynamic trajectory
+generation, nonlinear trajectory optimization, and nonlinear model predictive
+control. In simulation and real robot tests, we demonstrate that our
+motion-anisotropy-aware navigation framework could: (1) generate more efficient
+trajectories and realize more agile quadruped navigation; (2) significantly
+improve the navigation safety in challenging scenarios. The implementation is
+realized as an open-source package at
+https://github.com/ZWT006/agile_navigation.",2403.10101v1
+1996-03-08,A Line of Sight Approach to Cosmic Microwave Background Anisotropies,"We present a new method for calculating linear cosmic microwave background
+(CMB) anisotropy spectra based on integration over sources along the photon
+past light cone. In this approach the temperature anisotropy is written as a
+time integral over the product of a geometrical term and a source term. The
+geometrical term is given by radial eigenfunctions which do not depend on the
+particular cosmological model. The source term can be expressed in terms of
+photon, baryon and metric perturbations, all of which can be calculated using a
+small number of differential equations. This split clearly separates between
+the dynamical and geometrical effects on the CMB anisotropies. More
+importantly, it allows to significantly reduce the computational time compared
+to standard methods. This is achieved because the source term, which depends on
+the model and is generally the most time consuming part of calculation, is a
+slowly varying function of wavelength and needs to be evaluated only in a small
+number of points. The geometrical term, which oscillates much more rapidly than
+the source term, does not depend on the particular model and can be precomputed
+in advance. Standard methods that do not separate the two terms and require a
+much higher number of evaluations. The new method leads to about two orders of
+magnitude reduction in CPU time when compared to standard methods and typically
+requires a few minutes on a workstation for a single model. The method should
+be especially useful for accurate determinations of cosmological parameters
+from CMB anisotropy and polarization measurements that will become possible
+with the next generation of experiments. A programm implementing this method
+can be obtained from the authors.",9603033v1
+1999-09-01,Evolution of Multi-mass Globular Clusters in Galactic Tidal Field with the Effects of Velocity Anisotropy,"We study the evolution of globular clusters with mass spectra under the
+influence of the steady Galactic tidal field, including the effects of velocity
+anisotropy. Similar to single-mass models, velocity anisotropy develops as the
+cluster evolves, but the degree of anisotropy is much smaller than isolated
+clusters. Except for very early epochs of the cluster evolution, nearly all
+mass components become tangentially anisotropic at the outer parts. We have
+compared our results with multi-mass, King-Michie models. The isotropic King
+model better fits to the Fokker-Planck results because of tangential
+anisotropy. However, it is almost impossible to fit the computed density
+profiles to the multi-mass King models for all mass components. Thus if one
+attempts to derive global mass function based on the observed mass function in
+limited radial range using multi-mass King models, one may get somewhat erratic
+results, especially for low mass stars. We have examined how the mass function
+changes in time. Specifically, we find that the power-law index of the mass
+function decreases monotonically with the total mass of the cluster. This
+appears to be consistent with the behaviour of the observed slopes of mass
+functions for a limited number of clusters, although it is premature to compare
+quantitatively because there are other mechanisms in contributing the
+evaporation of stars from the clusters. The projected velocity profiles for
+anisotropic models with the apocenter criterion for evaporation show
+significant flattening toward the tidal radius compared to isotropic model or
+anisotropic model with the energy criterion. Such a behaviour of velocity
+profile appears to be consistent with the observed profiles of collapsed
+cluster M15.",9909006v1
+2001-03-06,The Anisotropy of the Ultra-High Energy Cosmic Rays,"Ultra-high energy cosmic rays (UHECRs) may originate from the decay of
+massive relic particles in the dark halo of the Galaxy, or they may be produced
+by supermassive black holes in the nuclei of nearby galaxies. The anisotropy in
+the arrival directions is studied in four dark halo models (cusped, isothermal,
+triaxial and tilted) and in four galaxy samples (galaxies intrinsically
+brighter than Centaurus A within 50 and 100 Mpc, and brighter than M32 within
+50 and 100 Mpc). In decaying dark matter models, the amplitude of the
+anisotropy is controlled by the size of the Galactic halo, while the phase is
+controlled by the shape. In the northern hemisphere, the amplitude is about 0.5
+for cusped haloes, but falls to roughly 0.3 for isothermal haloes. The phase
+points in the direction of the Galactic Centre, with deviations of up to 30
+degrees possible for triaxial and tilted haloes. The effect of the halo of M31
+is too weak to provide conclusive evidence for the decaying dark matter origin
+of UHECRs. In extragalactic models, samples of galaxies brighter than Centaurus
+A produce substantial anisotropies (roughly 1.8), much larger than the limits
+set by the available data. If all galaxies brighter than M32 contribute, then
+the anisotropy is more modest (roughly 0.5) and is directed toward mass
+concentrations in the supergalactic plane, like the Virgo cluster. Predictions
+are made for the southern hemisphere station of the Pierre Auger Observatory.
+If the UHECRs have a Galactic origin, then the phase points towards the
+Galactic Centre. If they have an extragalactic origin, then it points in the
+rough direction of the Fornax cluster. This provides an unambiguous
+discriminant and requires about 350-500 events at South Auger.",0103085v2
+2002-05-22,The Anisotropy of the Microwave Background to l = 3500: Deep Field Observations with the Cosmic Background Imager,"We report measurements of anisotropy in the cosmic microwave background
+radiation over the multipole range l ~ 200 - 3500 with the Cosmic Background
+Imager based on deep observations of three fields. These results confirm the
+drop in power with increasing l first reported in earlier measurements with
+this instrument, and extend the observations of this decline in power out to l
+\~ 2000. The decline in power is consistent with the predicted damping of
+primary anisotropies. At larger multipoles, l = 2000 - 3500, the power is 3.1
+sigma greater than standard models for intrinsic microwave background
+anisotropy in this multipole range, and 3.5 sigma greater than zero. This
+excess power is not consistent with expected levels of residual radio source
+contamination but, for sigma_8 >~ 1, is consistent with predicted levels due to
+a secondary Sunyaev-Zeldovich anisotropy. Further observations are necessary to
+confirm the level of this excess and, if confirmed, determine its origin.",0205384v2
+2003-09-11,Beyond the Damping Tail: Cross-Correlating the Kinetic Sunyaev-Zel'dovich Effect with Cosmic Shear,"Secondary anisotropies of the CMB have the potential to reveal intricate
+details about the history of our universe between the present and recombination
+epochs. However, because the CMB we observe is the projected sum of a multitude
+of effects, the interpretation of small scale anisotropies by future high
+resolution experiments will be marred by uncertainty and speculation without
+the handles provided by other observations. In this paper we show that cross
+correlating the CMB with an overlapping weak lensing survey will isolate the
+elusive kinetic Sunyaev-Zel'dovich Effect from secondary anisotropies generated
+at higher redshifts. We show that if upcoming high angular resolution CMB
+experiments, like PLANCK/ACT/SPT, cover the same area of sky as current and
+future weak lensing surveys, like CFTHLS/SNAP/LSST, the cross correlation of
+cosmic shear with the kSZ effect will be detected with high signal to noise
+ratio, increasing the potential science accessible to both sets of surveys. For
+example, if ACT and a CFHTLS like survey were to overlap this cross-correlation
+would be detected with a total signal to noise ratio greater than 220, reaching
+1.8 per individual multipole around l \sim 5000. Furthermore, this
+cross-correlation probes the three point coupling between the underlying dark
+matter and the ""momentum"" of the ionized baryons in the densest regions of the
+universe at intermediate redshifts. Similar to the tSZ power spectrum, its
+strength is extremely sensitive to the power spectrum normalization parameter,
+\sigma_8, scaling roughly as \sigma_8^7. It provides an effective mechanism to
+isolate any component of anisotropy due to patchy reionization and rule out
+primordial small scale anisotropy.",0309337v2
+2004-08-20,Galactic foreground contribution to the BEAST CMB Anisotropy Maps,"We report limits on the Galactic foreground emission contribution to the
+Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB
+anisotropy maps. We estimate the contribution from the cross-correlations
+between these maps and the foreground emission templates of an H${\alpha}$ map,
+a de-striped version of the Haslam et al. 408 MHz map, and a combined 100
+$\mu$m IRAS/DIRBE map. Our analysis samples the BEAST $\sim10^\circ$
+declination band into 24 one-hour (RA) wide sectors with $\sim7900$ pixels
+each, where we calculate: (a) the linear correlation coefficient between the
+anisotropy maps and the templates; (b) the coupling constants between the
+specific intensity units of the templates and the antenna temperature at the
+BEAST frequencies and (c) the individual foreground contributions to the BEAST
+anisotropy maps. The peak sector contributions of the contaminants in the
+Ka-band are of 56.5% free-free with a coupling constant of $8.3\pm0.4$
+$\mu$K/R, and 67.4% dust with $45.0\pm2.0$ $\mu$K/(MJy/sr). In the Q-band the
+corresponding values are of 64.4% free-free with $4.1\pm0.2$ $\mu$K/R and 67.5%
+dust with $24.0\pm1.0$ $\mu$K/(MJy/sr). Using a lower limit of 10% in the
+relative uncertainty of the coupling constants, we can constrain the sector
+contributions of each contaminant in both maps to $< 20$% in 21 (free-free), 19
+(dust) and 22 (synchrotron) sectors. At this level, all these sectors are found
+outside of the $\mid$b$\mid = 14.6^\circ$ region. By performing the same
+correlation analysis as a function of Galactic scale height, we conclude that
+the region within $b=\pm17.5^{\circ}$ should be removed from the BEAST maps for
+CMB studies in order to keep individual Galactic contributions below $\sim 1$%
+of the map's rms.",0408385v1
+2004-10-06,Constraining the Primordial Magnetic Field from Cosmic Microwave Background Anisotropies at Higher Multipoles,"The cosmological magnetic field is one of the important physical quantities
+which affect strongly the cosmic microwave background (CMB) power spectrum.
+Recent CMB observations have been extended to higher multipoles $l\gtrsim$1000,
+and they resultantly exhibit an excess power than the standard model prediction
+in cosmological theory which best fits the Wilkinson Microwave Anisotropy Probe
+(WMAP) data at lower multipoles $l\lesssim$900. We calculate the CMB
+temperature anisotropies generated by the power-law magnetic field at the last
+scattering surface (LSS) in order to remove the tension between theory and
+observation at higher multipoles and also place an upper limit on primordial
+magnetic field. In our present calculation we take account of the effect of
+ionization ratio exactly without approximation. This effect is very crucial to
+precisely estimate the effect of the magnetic field on CMB power spectrum. We
+consider both effects of the scalar and vector modes of magnetic field on the
+CMB anisotropies, where current data are known to be insensitive to the tensor
+mode which we ignore in the present study. In order to constrain the primordial
+magnetic field, we evaluate likelihood function of the WMAP data in a wide
+range of parameters of the magnetic field strength $|\mathbf{B}|_\lambda$ and
+the power-law spectral index $n$, along with six cosmological parameters in
+flat Universe models, using the technique of the Markov Chain Monte Carlo(MCMC)
+method. We find that the upper limit at $2\sigma$ C.L. turns out to be
+$|\mathbf{B}_\lambda|\lesssim 3.9 $nG at 1 Mpc for any $n_B$ values, which is
+obtained by comparing the calculated result including the Sunyaev-Zeldovich(SZ)
+effect with recent WMAP data of the CMB anisotropies.",0410142v3
+2004-12-08,"Anisotropies in the Neutrino Fluxes and Heating Profiles in Two-dimensional, Time-dependent, Multi-group Radiation Hydrodynamics Simulations of Rotating Core-Collapse Supernovae","Using the 2D multi-group, flux-limited diffusion version of the code
+VULCAN/2D, that also incorporates rotation, we have calculated the collapse,
+bounce, shock formation, and early post-bounce evolutionary phases of a
+core-collapse supernova for a variety of initial rotation rates. This is the
+first series of such multi-group calculations undertaken in supernova theory
+with fully multi-D tools. We find that though rotation generates
+pole-to-equator angular anisotropies in the neutrino radiation fields, the
+magnitude of the asymmetries is not as large as previously estimated. Moreover,
+we find that the radiation field is always more spherically symmetric than the
+matter distribution, with its plumes and convective eddies. We present the
+dependence of the angular anisotropy of the neutrino fields on neutrino
+species, neutrino energy, and initial rotation rate. Only for our most rapidly
+rotating model do we start to see qualitatively different hydrodynamics, but
+for the lower rates consistent with the pre-collapse rotational profiles
+derived in the literature the anisotropies, though interesting, are modest.
+This does not mean that rotation does not play a key role in supernova
+dynamics. The decrease in the effective gravity due to the centripetal effect
+can be quite important. Rather, it means that when a realistic mapping between
+initial and final rotational profiles and 2D multi-group
+radiation-hydrodynamics are incorporated into collapse simulations the
+anisotropy of the radiation fields may be only a secondary, not a pivotal
+factor, in the supernova mechanism.",0412187v3
+2006-01-16,Kinematical and Dynamical Modeling of Elliptical Galaxies,"Elements of kinematical and dynamical modeling of elliptical galaxies (Es)
+are presented. In projection, NFW models resemble Sersic models, but with a
+very narrow range of shapes (m=3+/-1). The total density profile of Es cannot
+be NFW-like because the predicted local M/L and aperture velocity dispersion
+within an effective radius (Re) are much lower than observed. Stars must then
+dominate Es out to a few Re. Fitting an NFW model to the total density profile
+of Sersic+NFW (stars+dark matter [DM]) Es results in very high concentration
+parameters, as found by X-ray observers. Kinematical modeling of Es assuming an
+isotropic NFW DM model underestimates M/L at the virial radius by a factor of
+1.6 to 2.4, because dissipationless LCDM halos have slightly different density
+profiles and slightly radial velocity anisotropy. In N-body+gas simulations of
+Es as merger remnants of spirals embedded in DM halos, the slope of the DM
+density profile is steeper when the initial spiral galaxies are gas-rich. The
+Hansen & Moore (2006) relation between anisotropy and the slope of the density
+profile breaks down for gas and DM, but the stars follow an analogous relation
+with slightly less radial anisotropies for a given density slope. Using
+kurtosis (h_4) to infer anisotropy in Es is dangerous, as h_4 is also sensitive
+to small levels of rotation. The stationary Jeans equation provides accurate
+masses out to 8 Re. The discrepancy between the modeling of Romanowsky et al.
+(2003), indicating a dearth of DM in Es, and the simulations analyzed by Dekel
+et al. (2005), which match the spectroscopic observations of Es, is partly due
+to radial anisotropy and to observing oblate Es face-on. However, one of the 15
+solutions to the orbit modeling of Romanowsky et al. is found to have an amount
+and concentration of DM consistent with LCDM predictions.",0601345v1
+2007-03-20,"The SAURON project -- X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/sigma,epsilon) diagram with integral-field stellar kinematics","We analyse the orbital distribution of E and S0 galaxies using SAURON
+integral-field stellar kinematics. We construct the anisotropy
+(V/sigma,epsilon) diagram, for the 48 E/S0 galaxies from the SAURON survey. For
+a subsample of 24 galaxies consistent with axisymmetry, we use three-integral
+axisymmetric Schwarzschild dynamical models to recover the detailed orbital
+distribution and we find good agreement with the anisotropy derived from the
+(V/sigma,epsilon) diagram. In the companion Paper IX we show that the
+early-type galaxies can be subdivided into two classes of systems with or
+without a significant amount of specific stellar angular momentum. Here we show
+that the two classes have different distributions on the (V/sigma,epsilon)
+diagram. The slow rotators are more common among the most massive systems and
+are generally classified as E from photometry alone. Those in our sample tend
+to be fairly round (epsilon<0.3), but can have significant kinematical
+misalignments, indicating that as a class they are moderately triaxial, and
+span a range of anisotropies (delta<0.3). The fast rotators are generally
+fainter and are classified either E or S0. They can appear quite flattened
+(epsilon<0.7), do not show significant kinematical misalignments (unless barred
+or interacting), indicating they are nearly axisymmetric, and span an even
+larger range of anisotropies (delta<0.5). These results are confirmed when we
+extend our analysis to 18 additional E/S0 galaxies observed with SAURON. All
+these results support the idea that fast rotators are nearly oblate and contain
+disk-like components. The role of gas must have been important for their
+formation. The slow rotators are weakly triaxial. Current collisionless merger
+models seem unable to explain their detailed observed properties. (Abridged)",0703533v1
+1993-03-25,Influence of cubic and dipolar anisotropies on the static and dynamic coexistence anomalies of the time-dependent Ginzburg-Landau models,"In isotropic systems below the transition temperature, the massless Goldstone
+modes imply critical infrared singularities in the statics and dynamics along
+the entire coexistence curve. We examine the important question whether these
+coexistence anomalies are of relevance also in more realistic systems
+displaying anisotropies. By applying a generalized renormalization scheme to
+the time-dependent Ginzburg-Landau models, we treat two quite different but
+characteristic cases, namely the influence of (i) weak cubic anisotropies, and
+(ii) long-range dipolar interactions. In the presence of cubic terms, the
+transverse excitations acquire a mass and thus one expects the theory to
+approach an uncritical ""Gaussian"" regime in the limit ${\vec q} \rightarrow 0$
+and $\omega \rightarrow 0$. Therefore, we first consider the one-component case
+in order to show that our formalism also provides a consistent description of
+the crossover into an asymptotically Gaussian theory. In the case of (weak)
+cubic anisotropies, the fact that for $n < 4$ the fluctuations tend to restore
+the $O(n)$-symmetry at the critical point proves to be most important, since
+under these circumstances coexistence-type singularities may be found in an
+intermediate wavenumber and frequency range. The dipolar interaction induces an
+anisotropy in momentum space, which does not completely destroy the massless
+character of the transverse fluctuations, but only effectively reduces the
+number of Goldstone modes by one. Remarkably, similar to the isotropic case the
+asymptotic theory can be treated exactly. For $n \geq 3$ we find coexistence
+anomalies governed by the isotropic power laws. However, the amplitudes of the
+respective scaling functions depend on the angle between order parameter and
+external wavevector.",9303044v1
+2008-03-07,Giant Uniaxial Anisotropy in the Magnetic and Transport Properties of CePd5Al2,"Electrical resistivity rho, magnetic susceptibility chi, magnetization M and
+specific heat measurements are reported on a singlecrystalline sample of
+CePd5Al2, showing successive antiferromagnetic orderings at T_N1=4.1 K and
+T_N2=2.9 K. The temperature dependence of T_N1 shows a Kondo metal behavior
+with large anisotropy, rho_c/rho_a=3.2 at 20 K, and opening of a superzone gap
+along the tetragona c-direction below T_N1. Both T_N1 and T_N2 gradually
+increase with applying pressure up to 2.5 GPa. The data of chi(T) and M(B) in
+the paramagnetic state were analyzed using a crystalline electric field (CEF)
+model. It led to a Kramers doublet ground state with wave functions consisting
+primarily of |+-5/2>, whose energy level is isolated from the excited states by
+230 and 300 K. This CEF effect gives rise to the large anisotropy in the
+paramagnetic state. In the ordered state, the uniaxial magnetic anisotropy is
+manifested as M_c/M_a=20 in B=5 T and at 1.9 K, and chi_c/chi_a=25 in B=0.1 T
+and at 4 K. This huge uniaxial magnetic anisotropy in the antiferromagnetic
+states can be interpreted in terms of isotropic magnetic interaction among the
+Ce^{3+} moments governed by the strong CEF. In powder neutron diffraction
+experiments, magnetic reflections were observed owing to the antiferromagnetic
+ordered states below T_N1, however, no additional reflection was found below
+T_N2.",0803.1078v3
+2008-06-13,The Large Scale Cosmic-Ray Anisotropy as Observed with Milagro,"Results are presented of a harmonic analysis of the large scale cosmic-ray
+anisotropy as observed by the Milagro observatory. We show a two-dimensional
+display of the sidereal anisotropy pro jections in right ascension generated by
+the fitting of three harmonics to 18 separate declination bands. The Milagro
+observatory is a water Cherenkov detector located in the Jemez mountains near
+Los Alamos, New Mexico. With a high duty cycle and large field-of-view, Milagro
+is an excellent instrument for measuring this anisotropy with high sensitivity
+at TeV energies. The analysis is conducted using a seven year data sample
+consisting of more than 95 billion events, the largest such data set in
+existence. We observe an anisotropy with a magnitude around 0.1% for cosmic
+rays with a median energy of 6 TeV. The dominant feature is a deficit region of
+depth (2.49 +/- 0.02 stat. +/- 0.09 sys.)x10^(-3) in the direction of the
+Galactic North Pole centered at 189 degrees right ascension. We observe a
+steady increase in the magnitude of the signal over seven years.",0806.2293v2
+2008-10-03,Spectra and anisotropy of magnetic fluctuations in the Earth's magnetosheath: Cluster observations,"We investigate the spectral shape, the anisotropy of the wave vector
+distributions and the anisotropy of the amplitudes of the magnetic fluctuations
+in the Earth's magnetosheath within a broad range of frequencies. We present
+the first observations of a Kolmogorov-like inertial range of Alfvenic
+fluctuations in the magnetosheath flanks, below fci. In the vicinity of fci, a
+spectral break is observed, like in solar wind turbulence. Above the break, the
+energy of compressive and Alfvenic fluctuations generally follow a power law
+with a spectral index between -3 and -2. Concerning the anisotropy of the wave
+vector distribution, we observe a change in its nature in the vicinity of ion
+characteristic scales: if at MHD scales there is no evidence for a dominance of
+a slab (k||>kperp) or 2D (kperp>k||) turbulence, above the spectral break,
+(f>fci, kc/wpi>1) the 2D turbulence dominates. This 2D turbulence is observed
+in six selected one-hour intervals among which the average proton beta varies
+from 0.8 to 9. It is observed for both the transverse and compressive magnetic
+fluctuations, independently on the presence of linearly unstable modes at low
+frequencies or Alfven vortices at the spectral break. We then analyse the
+anisotropy of the magnetic fluctuations in a time dependent reference frame
+based on the field B and the flow velocity V directions. Within the range of
+the 2D turbulence, at scales [1,30]kc/wpi, and for any beta we find that the
+magnetic fluctuations at a given frequency in the plane perpendicular to B have
+more energy along the BxV direction. This non-gyrotropy of the fluctuations is
+consistent with gyrotropic fluctuations at a given wave vector, with kperp>k||,
+which suffer a different Doppler shift along and perpendicular to V in the
+plane perpendicular to B.",0810.0675v1
+2009-03-26,Gamma-ray background anisotropy from galactic dark matter substructure,"Dark matter annihilation in galactic substructure would imprint
+characteristic angular signatures on the all-sky map of the diffuse gamma-ray
+background. We study the gamma-ray background anisotropy due to the subhalos
+and discuss detectability at Fermi Gamma-ray Space Telescope. We derive
+analytic formulae that enable to directly compute the angular power spectrum,
+given parameters of subhalos. As our fiducial subhalo models, we adopt M^{-1.9}
+mass spectrum, subhalos radial distribution suppressed towards the galactic
+center, and luminosity profile of each subhalo dominated by its smooth
+component. We find that, for multipole regime corresponding to \theta <~ 5 deg,
+the angular power spectrum is dominated by a noise-like term, with suppression
+due to internal structure of relevant subhalos. If the mass spectrum extends
+down to Earth-mass scale, then the subhalos would be detected in the anisotropy
+with Fermi at angular scales of ~10 deg, if their contribution to the gamma-ray
+background is larger than ~20%. If the minimum mass is around 10^4 M_{sun}, on
+the other hand, the relevant angular scale for detection is ~1 deg, and the
+anisotropy detection requires that the subhalo contribution to the gamma-ray
+background intensity is only ~4%. These can be achieved with a modest boost for
+particle physics parameters. We also find that the anisotropy analysis could be
+a more sensitive probe for the subhalos than individual detection. We also
+study dependence on model parameters, where we reach the similar conclusions
+for all the models investigated. The analytic approach should be very useful
+when Fermi data are analyzed and the obtained angular power spectrum is
+interpreted in terms of subhalo models.",0903.4685v2
+2010-02-21,A nonlinear theory of the parallel firehose and gyrothermal instabilities in a weakly collisional plasma,"Weakly collisional plasmas dynamically develop pressure anisotropies with
+respect to the magnetic field. These anisotropies trigger plasma instabilities
+at scales just above the ion Larmor radius \rho_i and much below the mean free
+path \lambda_{mfp}. They have growth rates of a fraction of the ion cyclotron
+frequency - much faster than either the global dynamics or local turbulence.
+The instabilities dramatically modify the transport properties and, therefore,
+the macroscopic dynamics of the plasma. Their nonlinear evolution drives
+pressure anisotropies towards marginal stability, controlled by the plasma beta
+\beta_i. Here this nonlinear evolution is worked out for the simplest
+analytically tractable example - the parallel firehose instability. In the
+nonlinear regime, both analytical theory and the numerical solution predict
+secular growth of magnetic fluctuations. They develop a k^{-3} spectrum,
+extending from scales somewhat larger than \rho_i to the maximum scale that
+grows secularly with time (~t^{1/2}); the relative pressure anisotropy
+(\pperp-\ppar)/\ppar tends to the marginal value -2/\beta_i. The marginal state
+is achieved via changes in the magnetic field, not particle scattering. When a
+parallel ion heat flux is present, the firehose mutates into the new
+gyrothermal instability (GTI), which continues to exist up to firehose-stable
+values of pressure anisotropy, which can be positive and are limited by the
+heat flux. The nonlinear evolution of the GTI also features secular growth of
+magnetic fluctuations, but the spectrum is eventually dominated by modes around
+the scale ~\rho_i l_T/\lambda_{mfp}, where l_T is the scale of the parallel
+temperature variation. Implications for momentum and heat transport are
+speculated about. This study is motivated by the dynamics of galaxy cluster
+plasmas.",1002.4017v2
+2010-04-01,Simulations of the cosmic infrared and submillimeter background for future large surveys: II. Removing the low-redshift contribution to the anisotropies using stacking,"Herschel and Planck are surveying the sky at unprecedented angular scales and
+sensitivities over large areas. But both experiments are limited by source
+confusion in the submillimeter. The high confusion noise in particular
+restricts the study of the clustering properties of the sources that dominate
+the cosmic infrared background. At these wavelengths, it is more appropriate to
+consider the statistics of the unresolved component. In particular, high
+clustering will contribute in excess of Poisson noise in the power spectra of
+CIB anisotropies. These power spectra contain contributions from sources at all
+redshift. We show how the stacking technique can be used to separate the
+different redshift contributions to the power spectra. We use simulations of
+CIB representative of realistic Spitzer, Herschel, Planck, and SCUBA-2
+observations. We stack the 24um sources in longer wavelengths maps to measure
+mean colors per redshift and flux bins. The information retrieved on the mean
+spectral energy distribution obtained with the stacking technique is then used
+to clean the maps, in particular to remove the contribution of low-redshift
+undetected sources to the anisotropies. Using the stacking, we measure the mean
+flux of populations 4 to 6 times fainter than the total noise at 350um at
+redshifts z=1 and z=2, respectively, and as faint as 6 to 10 times fainter than
+the total noise at 850um at the same redshifts. In the deep Spitzer fields, the
+detected 24um sources up to z~2 contribute significantly to the submillimeter
+anisotropies. We show that the method provides excellent (using COSMOS 24um
+data) to good (using SWIRE 24um data) removal of the z<2 (COSMOS) and z<1
+(SWIRE) anisotropies. Using this cleaning method, we then hope to have a set of
+large maps dominated by high redshift galaxies for galaxy evolution study
+(e.g., clustering, luminosity density).",1004.0123v1
+2010-07-25,Searching for a Cosmological Preferred Axis: Union2 Data Analysis and Comparison with Other Probes,"We review, compare and extend recent studies searching for evidence for a
+preferred cosmological axis. We start from the Union2 SnIa dataset and use the
+hemisphere comparison method to search for a preferred axis in the data. We
+find that the hemisphere of maximum accelerating expansion rate is in the
+direction $(l,b)=({309^\circ}^{+23^\circ}_{-3^\circ},
+{18^\circ}^{+11^\circ}_{-10^\circ})$ ($\omm=0.19$) while the hemisphere of
+minimum acceleration is in the opposite direction
+$(l,b)=({129^\circ}^{+23^\circ}_{-3^\circ},{-18^\circ}^{+10^\circ}_{-11^\circ})$
+($\omm=0.30$). The level of anisotropy is described by the normalized
+difference of the best fit values of $\omm$ between the two hemispheres in the
+context of \lcdm fits. We find a maximum anisotropy level in the Union2 data of
+$\frac{\Delta \ommax}{\bomm}=0.43\pm 0.06$. Such a level does not necessarily
+correspond to statistically significant anisotropy because it is reproduced by
+about $30%$ of simulated isotropic data mimicking the best fit Union2 dataset.
+However, when combined with the axes directions of other cosmological
+observations (bulk velocity flow axis, three axes of CMB low multipole moments
+and quasar optical polarization alignment axis), the statistical evidence for a
+cosmological anisotropy increases dramatically. We estimate the probability
+that the above independent six axes directions would be so close in the sky to
+be less than $1%$. Thus either the relative coincidence of these six axes is a
+very large statistical fluctuation or there is an underlying physical or
+systematic reason that leads to their correlation.",1007.4347v3
+2010-10-26,Generic role of the anisotropic surface free energy on the morphological evolution in a strained-heteroepitaxial solid droplet on a rigid substrate,"A systematic study based on the self-consistent dynamical simulations is
+presented for the spontaneous evolution of an isolated thin solid droplet on a
+rigid substrate, which is driven by the surface drift diffusion induced by the
+anisotropic capillary forces (surface stiffness) and mismatch stresses. In this
+work, we studied the affect of surface free energy anisotropies on the
+development kinetics of the 'Stranski-Krastanow' island type morphology. The
+anisotropic surface free energy and the surface stiffness were treated with
+well accepted trigonometric functions. Although, various tilt angles and
+anisotropy constants were considered during simulations, the main emphasis was
+given on the effect of rotational symmetries associated with the surface
+Helmholtz free energy topography in 2D space. Our computer simulations revealed
+the formation of an extremely thin wetting layer during the development of the
+bell-shaped Stranski-Krastanow island through the mass accumulation at the
+central region of the droplet via surface drift-diffusion. In the strong
+(anomalous) anisotropy constant domain, we demonstrated the existence of two
+distinct morphological modes: i) the complete stability of the initial
+Cosine-shaped droplet just above a certain anisotropy constant threshold level
+by spontaneous slight readjustments of the base and the height of the cluster;
+ii) the Frank-van der Merwe mode of thin film formation for very large values
+of the anisotropy constant by the spreading and coalescence of the droplets
+over the substrate surface. During the course of the simulations, we have
+continuously tracked both the morphology (i.e., the peak height, the extension
+of the wetting layer beyond the domain boundaries, and the triple junction
+contact angle) and energetic (the global Helmholtz free energy changes
+associated with the total strain and surface energy variations) of the system.",1010.5363v1
+2012-01-04,"Anisotropy of the irreversibility field for Zr-doped $(Y,Gd)Ba_2Cu_3O_{7-x}$ thin films up to 45T","The anisotropic irreversibility field B$_{Irr}$ of two $YBa_2Cu_3O_{7-x}$
+thin films doped with additional rare earth (RE)=(Gd,Y) and Zr and containing
+strong correlated pins (splayed BaZrO$_{3}$ nanorods, and $RE_2O_3$
+nanoprecipitates), has been measured over a very broad range up to 45T at
+temperatures 56 K<T<$T_c$. We found that the experimental angular dependence of
+$B_{Irr}(\theta)$ does not follow the mass anisotropy scaling
+$B_{Irr}(\theta)=B_{Irr}(0)(cos^2\theta+\gamma^{-2}sin^2\theta)^{-1/2}$, where
+$\gamma=(m_c/m_{ab})^{1/2}=5-6$ for the RE-doped $YBa_2Cu_3O_{7-x}$ (REBCO)
+crystals, m$_{ab}$ and m$_{c}$ are the effective masses along the ab plane and
+the c-axis, respectively, and $\theta$ is the angle between B and the c-axis.
+For B parallel to the ab-planes and to the c-axis correlated pinning strongly
+enhances B$_{Irr}$, while at intermediate angles, $B_{Irr}(\theta)$ follows the
+scaling behavior
+$B_{Irr}(\theta)\propto(cos^2\theta+\gamma_{RP}^2sin^2\theta)^{1/2}$ with the
+effective anisotropy factor $\gamma_{RP}\approx3$ significantly smaller than
+the mass anisotropy would suggest. In spite of the strong effects of c-axis
+BaZrO$_{3}$ nanorods, we found even greater enhancements of B$_{Irr}$ for
+fields along the ab-planes than for fields parallel to the c-axis, as well as
+different temperature dependences of the correlated pinning contributions to
+B$_{Irr}$ for B//ab and B//c. Our results show that the dense and strong pins,
+which can now be incorporated into REBCO thin films in a controlled way, exert
+major and diverse effects on the measured vortex pinning anisotropy and the
+irreversibility field over wide ranges of B and T. In particular, we show that
+the relative contribution of correlated pinning to B$_{Irr}$ for B//c increases
+as the temperature increases due to the suppression of thermal fluctuations of
+vortices by splayed distribution of BaZrO$_{3}$ nanorods.",1201.1020v1
+2012-05-10,The Near-IR Background Intensity and Anisotropies During The Epoch of Reionization,"A fraction of the extragalactic near-infrared (near-IR) background light
+involves redshifted photons from the ultraviolet (UV) emission from galaxies
+present during reionization at redshifts above 6. The absolute intensity and
+the anisotropies of the near-IR background provide an observational probe of
+the first-light galaxies and their spatial distribution. We estimate the
+extragalactic background light intensity during reionization by accounting for
+the stellar and nebular emission from first-light galaxies. We require the UV
+photon density from these galaxies to generate a reionization history that is
+consistent with the optical depth to electron scattering from cosmic microwave
+background measurements. We also require the bright-end luminosity function of
+galaxies in our models to reproduce the measured Lyman drop-out luminosity
+functions at redshifts of 6 to 8. The absolute intensity is about 0.1 to 0.3 nW
+m$^{-2}$ sr$^{-1}$ at the peak of its spectrum at $\sim$ 1.1 $\mu$m. We also
+discuss the anisotropy power spectrum of the near-IR background using a halo
+model to describe the galaxy distribution. We compare our predictions for the
+anisotropy power spectrum to existing measurements from deep near-IR imaging
+data from {\it Spitzer}/IRAC, {\it Hubble}/NICMOS, and {\it AKARI}. The
+predicted rms fluctuations at tens of arcminute angular scales are roughly an
+order of magnitude smaller than the existing measurements. While strong
+arguments have been made that the measured fluctuations do not have an origin
+involving faint low-redshift galaxies, we find that the existing measurements
+are also incompatible with an origin during the era of reionization. The
+measured near-IR background anisotropies remain unexplained and could be
+associated with an unidentified non-astrophysical origin.",1205.2316v3
+2012-05-31,Effect of temperature anisotropy on various modes and instabilities for a magnetized non-relativistic bi-Maxwellian plasma,"Using kinetic theory for homogeneous collisionless magnetized plasmas, we
+present an extended review of the plasma waves and instabilities and discuss
+the anisotropic response of generalized relativistic dielectric tensor and
+Onsager symmetry properties for arbitrary distribution functions. In general,
+we observe that for such plasmas only those electromagnetic modes whose
+magnetic field perturbations are perpendicular to the ambient magneticeld,
+i.e.,B1 \perp B0, are effected by the anisotropy. However, in oblique
+propagation all modes do show such anisotropic effects. Considering the
+non-relativistic bi-Maxwellian distribution and studying the relevant
+components of the general dielectric tensor under appropriate conditions, we
+derive the dispersion relations for various modes and instabilities. We show
+that only the electromagnetic R- and L- waves, those derived from them and the
+O-mode are affected by thermal anisotropies, since they satisfy the required
+condition B1\perpB0. By contrast, the perpendicularly propagating X-mode and
+the modes derived from it (the pure transverse X-mode and Bernstein mode) show
+no such effect. In general, we note that the thermal anisotropy modifies the
+parallel propagating modes via the parallel acoustic effect, while it modifies
+the perpendicular propagating modes via the Larmor-radius effect. In oblique
+propagation for kinetic Alfven waves, the thermal anisotropy affects the
+kinetic regime more than it affects the inertial regime. The generalized fast
+mode exhibits two distinct acoustic effects, one in the direction parallel to
+the ambient magnetic field and the other in the direction perpendicular to it.
+In the fast-mode instability, the magneto-sonic wave causes suppression of the
+firehose instability. We discuss all these propagation characteristics and
+present graphic illustrations.",1205.6896v1
+2013-05-17,A large anisotropy in the sky distribution of 3CRR quasars and other radio galaxies,"We report the presence of large anisotropies in the sky distributions of
+powerful extended quasars as well as some other sub-classes of radio galaxies
+in the 3CRR survey, the most reliable and most intensively studied complete
+sample of strong steep-spectrum radio sources. The anisotropies lie about a
+plane passing through the equinoxes and the north celestial pole. Out of a
+total of 48 quasars in the sample, 33 of them lie in one half of the observed
+sky and the remaining 15 in the other half. The probability that in a random
+distribution of 3CRR quasars in the sky, statistical fluctuations could give
+rise to an asymmetry in observed numbers up to this level is only $\sim 1\%$.
+Also only about 1/4th of Fanaroff-Riley 1 (FR1) type of radio galaxies lie in
+the first half of the observed sky and the remainder in the second half. If we
+include all the observed asymmetries in the sky distributions of quasars and
+radio galaxies in the 3CRR sample, the probability of their occurrence by a
+chance combination reduces to $\sim 2 \times 10^{-5}$. Two pertinent but
+disturbing questions that could be raised here are -- firstly why should there
+be such large anisotropies present in the sky distribution of some of the
+strongest and most distant discrete sources, implying inhomogeneities in the
+universe at very large scales (covering a fraction of the universe)? Secondly
+why should such anisotropies lie about a great circle decided purely by the
+orientation of earth's rotation axis and/or the axis of its revolution around
+the sun? Are these alignments a mere coincidence or do they imply that these
+axes have a preferential placement in the larger scheme of things, implying an
+apparent breakdown of the Copernican principle or its more generalization,
+cosmological principle, upon which the standard cosmological model is based
+upon?",1305.4134v2
+2013-07-31,Analytical families of 2-component anisotropic polytropes and their relativistic extensions,"In this paper, we study a family of two-component anisotropic polytropes
+which model a wide range of spherically symmetric astrophysical systems such as
+early-type baryonic galaxies. This family is found to contain a large class of
+models such as the hypervirial family (which satisfy the virial theorem
+locally), the Plummer and Hernquist models and Navarro-Frenk-White (NFW)-like
+models. The potential--density pair for these models are derived, as well as
+their velocity dispersions and anisotropy parameters. The projected quantities
+are computed and found to reduce to analytical expressions in some cases. The
+first section of this paper presents an extension of the two-term anisotropic
+polytropes to encompass a very wide range of potential-density pairs. In the
+next section, we present the general relativistic extension of the
+potential-density pair, and calculate the stress-energy tensor, the
+relativistic anisotropy parameter, the velocity of circular orbits and the
+angular momentum. Remarkably, for the case of the hypervirial family, the
+relativistic pressure in the Newtonian limit and the relativistic anisotropy
+parameter are found to coincide with the corresponding Newtonian expressions.
+The weak, dominant and strong energy conditions are found to be satisfied only
+for a certain range of the free parameters. We show that the relativistic
+hypervirial family also has a finite total mass like its Newtonian counterpart.
+In the first appendix, a relativistic extension of a different hypervirial
+family of models is studied, and the relativistic anisotropy parameter is found
+to coincide with the Newtonian one. Finally, we present a family of models
+obtained from our distribution function that are similar to the
+Ossipkov-Merritt models; by computing their anisotropy parameters, we show that
+they model systems with isotropic cores and radially anisotropic exteriors.",1307.8433v2
+2013-08-05,Environments of Extended Radio Sources in the ATLBS Survey,"We present a study of the environments of extended radio sources in the
+Australia Telescope Low Brightness Survey (ATLBS). The radio sources were
+selected from the Extended Source Sample (ATLBS-ESS), which is a well defined
+sample containing the most extended of radio sources in the ATLBS sky survey
+regions. The environments were analyzed using 4-m CTIO Blanco telescope
+observations carried out for ATLBS fields in the SDSS ${\rm r}^{\prime}$ band.
+We have estimated the properties of the environments using smoothed density
+maps derived from galaxy catalogs constructed using these optical imaging data.
+The angular distribution of galaxy density relative to the axes of the radio
+sources has been quantified by defining anisotropy parameters that are
+estimated using a new method presented here. Examining the anisotropy
+parameters for a sub-sample of extended double radio sources that includes all
+sources with pronounced asymmetry in lobe extents, we find good evidence for
+environmental anisotropy being the dominant cause for lobe asymmetry in that
+higher galaxy density occurs almost always on the side of the shorter lobe, and
+this validates the usefulness of the method proposed and adopted here. The
+environmental anisotropy parameters have been used to examine and compare the
+environments of FRI and FRII radio sources in two redshift regimes ($z<0.5$ and
+$z>0.5$). Wide-angle tail sources and Head-tail sources lie in the most
+overdense environments. The Head-tail source environments (for the HT sources
+in our sample) display dipolar anisotropy in that higher galaxy density appears
+to lie in the direction of the tails. Excluding the Head-tail and Wide-angle
+tail sources, subsamples of FRI and FRII sources from the ATLBS survey appear
+to lie in similar moderately overdense environments, with no evidence for
+redshift evolution in the regimes studied herein.",1308.0884v1
+2013-11-05,"Mass, velocity anisotropy, and pseudo phase-space density profiles of Abell 2142","Aim: We aim to compute the mass and velocity anisotropy profiles of Abell
+2142 and, from there, the pseudo phase--space density profile $Q(r)$ and the
+density slope - velocity anisotropy $\beta - \gamma$ relation, and then to
+compare them with theoretical expectations. Methods: The mass profiles were
+obtained by using three techniques based on member galaxy kinematics, namely
+the caustic method, the method of Dispersion - Kurtosis, and MAMPOSSt. Through
+the inversion of the Jeans equation, it was possible to compute the velocity
+anisotropy profiles. Results: The mass profiles, as well as the virial values
+of mass and radius, computed with the different techniques agree with one
+another and with the estimates coming from X-ray and weak lensing studies. A
+concordance mass profile is obtained by averaging the lensing, X-ray, and
+kinematics determinations. The cluster mass profile is well fitted by an NFW
+profile with $c=4.0 \pm 0.5$. The population of red and blue galaxies appear to
+have a different velocity anisotropy configuration, since red galaxies are
+almost isotropic, while blue galaxies are radially anisotropic, with a weak
+dependence on radius. The $Q(r)$ profile for the red galaxy population agrees
+with the theoretical results found in cosmological simulations, suggesting that
+any bias, relative to the dark matter particles, in velocity dispersion of the
+red component is independent of radius. The $\beta - \gamma$ relation for red
+galaxies matches the theoretical relation only in the inner region. The
+deviations might be due to the use of galaxies as tracers of the gravitational
+potential, unlike the non--collisional tracer used in the theoretical relation.",1311.1210v4
+2013-11-23,The effects of structure anisotropy on lensing observables in an exact general relativistic setting for precision cosmology,"The study of relativistic, higher order and nonlinear effects has become
+necessary in recent years in the pursuit of precision cosmology. We develop and
+apply here a framework to study gravitational lensing in exact models in
+general relativity that are not restricted to homogeneity and isotropy, and
+where full nonlinearity and relativistic effects are included. We apply the
+framework to a specific, anisotropic galaxy cluster model which is based on a
+modified NFW halo density profile and described by the Szekeres metric. We
+examine the effects of increasing levels of anisotropy in the galaxy cluster on
+lensing observables like the convergence and shear for various lensing
+geometries, finding a strong nonlinear response in both the convergence and
+shear for rays passing through anisotropic regions of the cluster. Deviation
+from the expected values in a spherically symmetric structure are asymmetric
+with respect to path direction and thus will persist as a statistical effect
+when averaged over some ensemble of such clusters. The resulting relative
+difference in various geometries can be as large as approximately 2%, 8%, and
+24% in the measure of convergence for levels of anisotropy of 5%, 10%, and 15%,
+respectively, as a fraction of total cluster mass. For the total magnitude of
+shear, the relative difference can grow near the center of the structure to be
+as large as 15%, 32%, and 44% for the same levels of anisotropy, averaged over
+the two extreme geometries. The convergence is impacted most strongly for rays
+which pass in directions along the axis of maximum dipole anisotropy in the
+structure, while the shear is most strongly impacted for rays which pass in
+directions orthogonal to this axis, as expected. These effects due to
+anisotropic structures will affect lensing measurements and must be fully
+examined in an era of precision cosmology.",1311.5936v2
+2014-02-13,Trend of the magnetic anisotropy for individual Mn dopants near the (110) GaAs surface,"Using a microscopic finite-cluster tight-binding model, we investigate the
+trend of the magnetic anisotropy energy as a function of the cluster size for
+an individual Mn impurity positioned in the vicinity of the (110) GaAs
+surface,We present results of calculations for large cluster sizes, containing
+approximately 104 atoms, which have not been investigated so far. Our
+calculations demonstrate that the anisotropy energy of a Mn dopant in bulk GaAs
+found to be non-zero in previous tight-binding calculations, is purely a finite
+size effect, and it vanishes as the inverse cluster size. In contrast to this,
+we find that the splitting of the three in-gap Mn acceptor energy levels
+converges to a finite value in the limit of infinite cluster size. For a Mn in
+bulk GaAs this feature is related to the nature of the mean-field treatment of
+the coupling between the impurity and its nearest neighbors atoms. Moreover, we
+calculate the trend of the anisotropy energy in the sublayers, as the Mn dopant
+is moved away from the surface towards the center of the cluster. Here the use
+of large cluster sizes allows us to position the impurity in deeper sublayers
+below the surface, compared to previous calculations. In particular, we show
+that the anisotropy energy increases up to the fifth sublayer and then
+decreases as the impurity is moved further away from the surface, approaching
+its bulk value. The present study provides important insight for experimental
+control and manipulation of the electronic and magnetic properties of
+individual Mn dopants at the semiconductor surface by means of advanced
+scanning tunneling microscopy techniques.",1402.3069v2
+2014-03-18,Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies,"The BICEP2 collaboration has reported a strong B mode signal in the CMB
+polarization, which is well fit by a tensor-to-scalar ratio of r ~ 0.2. This is
+greater than the upper limit r < 0.11 obtained from the temperature
+anisotropies under the assumption of a constant scalar spectral index n_s. This
+discrepancy can be reduced once the statistical error and the contamination
+from polarized dust are accounted for. If however a large value for r will be
+confirmed, it will need to be reconciled with the temperature anisotropies
+data. The most advocated explanation involves a variation of n_s with scales
+(denoted as running) that has a magnitude significantly greater than the
+generic slow roll predictions. We instead study the possibility that the large
+scale temperature anisotropies are not enhanced because of a suppression of the
+scalar power at large scales. Such a situation can be achieved for instance by
+a sudden change of the speed of the inflaton (by about 14 %), and we show that
+it fits the temperature anisotropies and polarization data considerably better
+than a constant running (its chi^2 improves by ~ 7.5 over that of the constant
+running, at the cost of one more parameter). We also consider the possibility
+that the large scale temperature fluctuations are suppressed by an
+anti-correlation between tensor and scalar modes. Unfortunately, while such
+effect does affect the temperature fluctuations at large scales, it does not
+affect the temperature power spectrum and cannot, therefore, help in
+reconciling a large value of r with the limits from temperature fluctuations.",1403.4596v4
+2014-07-08,On the Observation of the Cosmic Ray Anisotropy below 10$^{15}$ eV,"The measurement of the anisotropy in the arrival direction of cosmic rays is
+complementary to the study of their energy spectrum and chemical composition to
+understand their origin and propagation. It is also a tool to probe the
+structure of the magnetic fields through which cosmic rays travel. As cosmic
+rays are mostly charged nuclei, their trajectories are deflected by the action
+of galactic magnetic field they propagate through before reaching the Earth
+atmosphere, so that their detection carries directional information only up to
+distances as large as their gyro-radius. If cosmic rays below
+$10^{15}{\rm\,eV}$ are considered and the local galactic magnetic field
+($\sim3{\rm\,\mu G}$) is accounted for, gyro-radii are so short that isotropy
+is expected. At most, a weak di-polar distribution may exist, reflecting the
+contribution of the closest CR sources. However, a number of experiments
+observed an energy-dependent \emph{""large scale""} anisotropy in the sidereal
+time frame with an amplitude of about 10$^{-4}$ - 10$^{-3}$, revealing the
+existence of two distinct broad regions: an excess distributed around
+40$^{\circ}$ to 90$^{\circ}$ in Right Ascension (commonly referred to as
+""tail.in"" excess) and a deficit (the ""loss cone"") around 150$^{\circ}$ to
+240$^{\circ}$ in Right Ascension. In recent years the Milagro and ARGO-YBJ
+collaborations reported the of a ""medium"" scale anisotropy inside the tail-in
+region. The observation of such small features has been recently claimed by the
+IceCube experiment also in the Southern hemisphere. So far, no theory of cosmic
+rays in the Galaxy exists which is able to explain the origin of these
+different anisotropies leaving the standard model of cosmic rays and that of
+the galactic magnetic field unchanged at the same time.",1407.2144v1
+2014-10-22,On the Anisotropic Nature of MRI-Driven Turbulence in Astrophysical Disks,"The magnetorotational instability is thought to play an important role in
+enabling accretion in sufficiently ionized astrophysical disks. The rate at
+which MRI-driven turbulence transports angular momentum is related to both the
+strength of the amplitudes of the fluctuations on various scales and the degree
+of anisotropy of the underlying turbulence. This has motivated several studies
+of the distribution of turbulent power in spectral space. In this paper, we
+investigate the anisotropic nature of MRI-driven turbulence using a
+pseudo-spectral code and introduce novel ways to robustly characterize the
+underlying turbulence. We show that the general flow properties vary in a
+quasi-periodic way on timescales comparable to 10 inverse angular frequencies
+motivating the temporal analysis of its anisotropy. We introduce a 3D tensor
+invariant analysis to quantify and classify the evolution of the anisotropic
+turbulent flow. This analysis shows a continuous high level of anisotropy, with
+brief sporadic transitions towards two- and three-component isotropic turbulent
+flow. This temporal-dependent anisotropy renders standard shell-average,
+especially when used simultaneously with long temporal averages, inadequate for
+characterizing MRI-driven turbulence. We propose an alternative way to extract
+spectral information from the turbulent magnetized flow, whose anisotropic
+character depends strongly on time. This consists of stacking 1D Fourier
+spectra along three orthogonal directions that exhibit maximum anisotropy in
+Fourier space. The resulting averaged spectra show that the power along each of
+the three independent directions differs by several orders of magnitude over
+most scales, except the largest ones. Our results suggest that a
+first-principles theory to describe fully developed MRI-driven turbulence will
+likely have to consider the anisotropic nature of the flow at a fundamental
+level.",1410.6196v1
+2014-11-11,Electron-vibron coupling effects on electron transport via a single-molecule magnet,"We investigate how the electron-vibron coupling influences electron transport
+via an anisotropic magnetic molecule, such as a single-molecule magnet (SMM)
+Fe$_4$, by using a model Hamiltonian with parameter values obtained from
+density-functional theory (DFT). Magnetic anisotropy parameters, vibrational
+energies, and electron-vibron coupling strengths of the Fe$_4$ are computed
+using DFT. A giant spin model is applied to the Fe$_4$ with only two charge
+states, specifically a neutral state with the total spin $S=5$ and a singly
+charged state with $S=9/2$, which is consistent with our DFT result and
+experiments on Fe$_4$ single-molecule transistors. In sequential electron
+tunneling, we find that the magnetic anisotropy gives rise to new features in
+conductance peaks arising from vibrational excitations. In particular, the peak
+height shows a strong, unusual dependence on the direction as well as magnitude
+of applied B field. The magnetic anisotropy also introduces vibrational
+satellite peaks whose position and height are modified with the direction and
+magnitude of applied B field. Furthermore, when multiple vibrational modes with
+considerable electron-vibron coupling have energies close to one another, a
+low-bias current is suppressed, independently of gate voltage and applied B
+field, although that is not the case for a single mode with the similar
+electron-vibron coupling. In the former case, the conductance peaks reveal a
+stronger B-field dependence than in the latter case. The new features appear
+because the magnetic anisotropy barrier is of the same order of magnitude as
+the energies of vibrational modes with significant electron-vibron coupling.
+Our findings clearly show the interesting interplay between magnetic anisotropy
+and electron-vibron coupling in electron transport via the Fe$_4$. The similar
+behavior can be observed in transport via other anisotropic magnetic molecules.",1411.2677v1
+2014-12-15,Isotropy constraints on powerful sources of ultrahigh-energy cosmic rays at $10^{19}$ eV,"Anisotropy in the arrival direction distribution of ultrahigh-energy cosmic
+rays (UHECRs) produced by powerful sources is numerically evaluated. We show
+that, taking account of the Galactic magnetic field, nondetection of
+significant anisotropy at $\approx 10^{19}$ eV at present and in future
+experiments imposes general upper limits on UHECR proton luminosity of steady
+sources as a function of source redshifts. The upper limits constrain the
+existence of typical steady sources in the local universe and limit the local
+density of $10^{19}$ eV UHECR sources to be $\gtrsim 10^{-3}$ Mpc$^{-3},$
+assuming average intergalactic magnetic fields less than $10^{-9}$ G. This
+isotropy, which is stronger than measured at the highest energies, may indicate
+the transient generation of UHECRs. Our anisotropy calculations are applied for
+extreme high-frequency-peaked BL Lac objects 1ES 0229+200, 1ES 1101-232, and
+1ES 0347-121, to test the UHECR-induced cascade model, in which beamed UHECR
+protons generate TeV radiation in transit from sources. While the
+magnetic-field structure surrounding the sources affects the required absolute
+cosmic-ray luminosity of the blazars, the magnetic-field structure surrounding
+the Milky Way directly affects the observed anisotropy. If both of the magnetic
+fields are weak enough, significant UHECR anisotropy from these blazars should
+be detectable by the Pierre Auger Observatory unless the maximum energy of
+UHECR protons is well below $10^{19}$ eV. Furthermore, if these are the sources
+of UHECRs above $10^{19}$ eV, a local magnetic structure surrounding the Milky
+Way is needed to explain the observed isotropy at $\sim 10^{19}$ eV, which may
+be incompatible with large magnetic structures around all galaxies for the
+UHECR-induced cascade model to work with reasonable jet powers.",1412.4716v3
+2015-03-09,I-Love-Q anisotropically: Universal relations for compact stars with scalar pressure anisotropy,"Certain physical quantities that characterize neutron stars and quark stars
+(e.g. their mass, spin angular momentum and quadrupole moment) are interrelated
+in a way that is approximately insensitive to their internal structure. Such
+approximately universal relations are useful to break degeneracies in data
+analysis for future radio, X-ray and gravitational wave observations. Although
+the pressure inside compact stars is most likely nearly isotropic, certain
+scenarios have been put forth that suggest otherwise, for example due to phase
+transitions. We here investigate whether pressure anisotropy affects the
+approximate universal relations and whether it prevents their use in future
+observations. We achieve this by numerically constructing slowly-rotating and
+tidally-deformed, anisotropic, compact stars in General Relativity to third
+order in spin. We find that anisotropy affects the universal relations only
+weakly; the relations become less universal by a factor of 1.5-3 relative to
+the isotropic case, but remain approximately universal to 10%. We succeed in
+explaining this increase in variability as an increase in the eccentricity
+variation of isodensity contours, which provides further support for the
+emergent approximate symmetry explanation of universality. Anisotropy does not
+affect the universal relations to a sufficient level to prevent their use in
+gravitational wave astrophysics or in experimental relativity. We provide an
+explicit example of the latter in dynamical Chern-Simons gravity. The increase
+in variability of the universal relations due to pressure anisotropy could
+affect their use in future X-ray observations. Given expected observational
+uncertainties, however, the relations remain sufficiently universal for use in
+such observations if the anisotropic modifications to the moment of inertia and
+the quadrupole moment are less than 10% of their isotropic values.",1503.02726v2
+2016-08-15,"Physical properties of single crystalline $R$Mg$_{2}$Cu$_{9}$ ($R$ = Y, Ce-Nd, Gd-Dy, Yb) and the search for in-plane magnetic anisotropy in hexagonal systems","Single crystals of $R$Mg$_{2}$Cu$_{9}$ ($R$=Y, Ce-Nd, Gd-Dy, Yb) were grown
+using a high-temperature solution growth technique and were characterized by
+measurements of room-temperature x-ray diffraction, temperature-dependent
+specific heat and temperature-, field-dependent resistivity and anisotropic
+magnetization. YMg$_{2}$Cu$_{9}$ is a non-local-moment-bearing metal with an
+electronic specific heat coefficient, $\gamma \sim$ 15 mJ/mol K$^2$. Yb is
+divalent and basically non-moment bearing in YbMg$_{2}$Cu$_{9}$. Ce is
+trivalent in CeMg$_{2}$Cu$_{9}$ with two magnetic transitions being observed at
+2.1 K and 1.5 K. PrMg$_{2}$Cu$_{9}$ does not exhibit any magnetic phase
+transition down to 0.5 K. The other members being studied ($R$=Nd, Gd-Dy) all
+exhibits antiferromagnetic transitions at low-temperatures ranging from 3.2 K
+for NdMg$_{2}$Cu$_{9}$ to 11.9 K for TbMg$_{2}$Cu$_{9}$. Whereas
+GdMg$_{2}$Cu$_{9}$ is isotropic in its paramagnetic state due to zero angular
+momentum ($L$=0), all the other local-moment-bearing members manifest an
+anisotropic, planar magnetization in their paramagnetic states. To further
+study this planar anisotropy, detailed angular-dependent magnetization was
+carried out on magnetically diluted (Y$_{0.99}$Tb$_{0.01}$)Mg$_{2}$Cu$_{9}$ and
+(Y$_{0.99}$Dy$_{0.01}$)Mg$_{2}$Cu$_{9}$. Despite the strong, planar
+magnetization anisotropy, the in-plane magnetic anisotropy is weak and
+field-dependent. A set of crystal electric field parameters are proposed to
+explain the observed magnetic anisotropy.",1608.04310v1
+2017-05-16,A novel JEAnS analysis of the Fornax dwarf using evolutionary algorithms: mass follows light with signs of an off-centre merger,"Dwarf galaxies, among the most dark matter dominated structures of our
+universe, are excellent test-beds for dark matter theories. Unfortunately, mass
+modelling of these systems suffers from the well documented mass-velocity
+anisotropy degeneracy. For the case of spherically symmetric systems, we
+describe a method for non-parametric modelling of the radial and tangential
+velocity moments. The method is a numerical velocity anisotropy ""inversion"",
+with parametric mass models, where the radial velocity dispersion profile,
+$\sigma_{\mathrm{rr}}^2$ is modeled as a B-spline, and the optimization is a
+three step process that consists of: (i) an Evolutionary modelling to determine
+the mass model form and the best B-spline basis to represent
+$\sigma_{\mathrm{rr}}^2$; (ii) an optimization of the smoothing parameters;
+(iii) a Markov chain Monte Carlo analysis to determine the physical parameters.
+The mass-anisotropy degeneracy is reduced into mass model inference,
+irrespective of kinematics. We test our method using synthetic data. Our
+algorithm constructs the best kinematic profile and discriminates between
+competing dark matter models. We apply our method to the Fornax dwarf
+spheroidal galaxy. Using a King brightness profile and testing various dark
+matter mass models, our model inference favours a simple mass-follows-light
+system. We find that the anisotropy profile of Fornax is tangential ($\beta(r)
+< 0$) and we estimate a total mass of $M_{\text{tot}} = 1.613
+^{+0.050}_{-0.075} \times 10^8 \, \text{M}_{\odot}$, and a mass-to-light ratio
+of $\Upsilon_V = 8.93 ^{+0.32}_{-0.47} \, (\text{M}_{\odot}/\text{L}_{\odot})$.
+The algorithm we present is a robust and computationally inexpensive method for
+non-parametric modelling of spherical clusters independent of the
+mass-anisotropy degeneracy.",1705.05724v1
+2017-08-13,PIC Simulations of Velocity-Space Instabilities in a Decreasing Magnetic Field: Viscosity and Thermal Conduction,"We use particle-in-cell (PIC) simulations of a collisionless, electron-ion
+plasma with a decreasing background magnetic field, $B$, to study the effect of
+velocity-space instabilities on the viscous heating and thermal conduction of
+the plasma. If $B$ decreases, the adiabatic invariance of the magnetic moment
+gives rise to pressure anisotropies with $p_{||,j} > p_{\perp,j}$ ($p_{||,j}$
+and $p_{\perp,j}$ represent the pressure of species $j$ ($=i$ or $e$) parallel
+and perpendicular to the magnetic field). Linear theory indicates that, for
+sufficiently large anisotropies, different velocity-space instabilities can be
+triggered. These instabilities, which grow on scales comparable to the electron
+and ion Larmor radii, in principle have the ability to pitch-angle scatter the
+particles, limiting the growth of the anisotropies. Our PIC simulations focus
+on the nonlinear, saturated regime of the instabilities. This is done through
+the permanent decrease of the magnetic field by an imposed shear in the plasma.
+Our results show that, in the regime $2 \lesssim \beta_j \lesssim 20$ ($\beta_j
+\equiv 8\pi p_j/B^2$), the saturated ion and electron pressure anisotropies are
+controlled by the combined effect of the oblique ion firehose (OIF) and the
+fast magnetosonic/whistler (FM/W) instabilities. These instabilities grow
+preferentially on the ion Larmor radius scale, and make the ion and electron
+pressure anisotropies nearly equal: $\Delta p_e/p_{||,e} \approx \Delta
+p_i/p_{||,i}$ (where $\Delta p_j=p_{\perp,j} - p_{||,j}$). We also quantify the
+thermal conduction of the plasma by directly calculating the mean free path of
+electrons along the mean magnetic field, which we find strongly depends on
+whether $B$ decreases or increases. Our results can be applied in studies of
+low collisionality plasmas such as the solar wind, the intracluster medium, and
+some accretion disks around black holes.",1708.03926v2
+2017-10-05,Planck 2015 constraints on the non-flat XCDM inflation model,"We study Planck 2015 cosmic microwave background (CMB) anisotropy data using
+the energy density inhomogeneity power spectrum generated by quantum
+fluctuations during an early epoch of inflation in the non-flat XCDM model.
+Here dark energy is parameterized using a fluid with a negative equation of
+state parameter but with the speed of fluid acoustic inhomogeneities set to the
+speed of light. We use this simple parameterization of dynamical dark energy,
+that is relatively straightforward to use in a computation, in a first attempt
+to gain some insight into how dark energy dynamics and non-zero spatial
+curvature jointly affect the CMB anisotropy data constraints. Unlike earlier
+analyses of non-flat models, we use a physically consistent power spectrum for
+energy density inhomogeneities. We find that the Planck 2015 data in
+conjunction with baryon acoustic oscillation measurements are reasonably well
+fit by a closed XCDM model in which spatial curvature contributes a percent of
+the current cosmological energy density budget. In this model, the measured
+Hubble constant and non-relativistic matter density parameter are in good
+agreement with values determined using most other data. Depending on parameter
+values, the closed XCDM model has reduced power, relative to the tilted,
+spatially-flat $\Lambda$CDM case, and appears to partially alleviate the low
+multipole CMB temperature anisotropy deficit and can help partially reconcile
+the CMB anisotropy and weak lensing $\sigma_8$ constraints, at the expense of
+somewhat worsening the fit to higher multipole CMB temperature anisotropy data.
+However, the closed XCDM inflation model does not seem to improve the agreement
+much, if at all, compared to the closed $\Lambda$CDM inflation case, even
+though it has one more free parameter. Our results are interesting but
+tentative; a more thorough analysis is needed to properly gauge their
+significance.",1710.03271v2
+2017-10-09,Influence of classical anisotropy fields on the properties of Heisenberg antiferromagnets within unified molecular field theory,"A comprehensive study of the influence of classical anisotropy fields on the
+magnetic properties of Heisenberg antiferromagnets within unified molecular
+field theory versus temperature T, magnetic field H, and anisotropy field
+parameter hA1 is presented for systems comprised of identical
+crystallographically-equivalent local moments. The anisotropy field for
+collinear z-axis antiferromagnetic (AFM) ordering is constructed so that it is
+aligned in the direction of each ordered and/or field-induced thermal-average
+moment with a magnitude proportional to the moment, whereas that for XY
+anisotropy is defined to be in the direction of the projection of the moment
+onto the xy plane, again with a magnitude proportional to the moment.
+Properties studied include the zero-field Neel temperature TN, ordered moment,
+heat capacity and anisotropic magnetic susceptibility of the AFM phase versus T
+with moments aligned either along the z axis or in the xy plane. Also
+determined are the high-field magnetization perpendicular to the axis or plane
+of collinear or planar noncollinear AFM ordering, the high-field magnetization
+along the z axis of a collinear z-axis AFM, spin-flop (SF), and paramagnetic
+(PM) phases, and the free energies of these phases versus T, H, and hA1. Phase
+diagrams at T = 0 in the Hz-hA1 plane and at T > 0 in the Hz-T plane are
+constructed for spins S = 1/2. For hA1 = 0 the SF phase is stable at low field
+and the PM phase at high field with no AFM phase present. As hA1 increases, the
+phase diagram contains the AFM, SF and PM phases. Further increases in hA1 lead
+to the disappearance of the SF phase and the appearance of a tricritical point
+on the AFM-PM transition curve. Applications of the theory to extract hA1 from
+experimental low-field magnetic susceptibility data and high-field
+magnetization versus field isotherms for single crystals of AFMs are discussed.",1710.03750v1
+2017-11-21,Thickness-dependence of the Dzyaloshinskii-Moriya interaction in Co2FeAl ultrathin films: effects of the annealing temperature and the heavy metal material,"Interfacial Dzyaloshinskii-Moriya interaction (iDMI) has been investigated in
+Co2FeAl (CFA) ultrathin films of various thicknesses (0.8 nm<tCFA<2 nm) grown
+on Si substrates, using Pt, W, Ir and MgO buffer or/and capping layers.
+Vibrating sample magnetometry revealed that magnetization at saturation (Ms)
+for the Pt and Ir buffered films is higher than the usual Ms of CFA due to the
+proximity induced magnetization (PIM) in Ir and Pt, estimated to be 19% and
+27%, respectively. The presence of PIM in these materials is confirmed using
+x-ray resonant magnetic reflectivity. Moreover, while no PIM is induced in W,
+higher PIM is obtained with Pt when it is used as buffer layer rather than
+capping layer. Brillouin light scattering (BLS) in the Damon-Eshbach geometry
+has been used to investigate iDMI constants and the perpendicular anisotropy
+field versus the annealing temperature. The DMI sign has been found to be
+negative for Pt/CFA and Ir/CFA while it is positive for W/CFA. The thickness
+dependence of the effective iDMI constant for stacks involving Pt and W shows
+the existence of two regimes similarly to that of the perpendicular anisotropy
+constant due to the degradation of the interfaces as the CFA thickness
+approaches the nanometer. The surface iDMI and anisotropy constants of each
+stack have been determined for the thickest samples where a linear thickness
+dependence of the effective iDMI constant and the effective magnetization has
+been observed. The interface anisotropy and iDMI constants, investigated for
+Pt/CFA/MgO system, showed different trends with the annealing temperature. The
+decrease of iDMI constant with increasing annealing temperature is probably due
+to the electronic structure changes at the interfaces, while the increase of
+the interface anisotropy constant is coherent the interface quality and
+disorder enhancement.",1711.07776v1
+2017-12-05,Accurate estimation of microscopic diffusion anisotropy and its time dependence in the mouse brain,"Microscopic diffusion anisotropy ({\mu}A) has been recently gaining
+increasing attention for its ability to decouple the average compartment
+anisotropy from orientation dispersion. Advanced diffusion MRI sequences, such
+as double diffusion encoding (DDE) and double oscillating diffusion encoding
+(DODE) have been used for mapping {\mu}A. However, the time-dependence of
+{\mu}A has not been investigated insofar, and furthermore, the accuracy of
+{\mu}A estimation vis-\`a-vis different b-values was not assessed. Here, we
+investigate both these concepts using theory, simulation, and experiments in
+the mouse brain. In the first part, simulations and experimental results show
+that the conventional estimation of microscopic anisotropy from the difference
+of D(O)DE sequences with parallel and orthogonal gradient directions yields
+values that highly depend on the choice of b-value. To mitigate this
+undesirable bias, we propose a multi-shell approach that harnesses a polynomial
+fit of the signal difference up to third order terms in b-value. In
+simulations, this approach yields more accurate {\mu}A metrics, which are
+similar to the ground truth values. The second part of this work uses the
+proposed multi-shell method to estimate the time/frequency dependence of
+{\mu}A. The data shows either an increase or no change in {\mu}A with frequency
+depending on the region of interest, both in white and gray matter. When
+comparing the experimental results with simulations, it emerges that simple
+geometric models such as infinite cylinders with either negligible or finite
+radii cannot replicate the measured trend, and more complex models, which, for
+example, incorporate structure along the fibre direction are required. Thus,
+measuring the time dependence of microscopic anisotropy can provide valuable
+information for characterizing tissue microstructure.",1712.01954v2
+2018-02-27,Extracting foreground-obscured $μ$-distortion anisotropies to constrain primordial non-Gaussianity,"Correlations between cosmic microwave background (CMB) temperature,
+polarization and spectral distortion anisotropies can be used as a probe of
+primordial non-Gaussianity. Here, we perform a reconstruction of
+$\mu$-distortion anisotropies in the presence of Galactic and extragalactic
+foregrounds, applying the so-called Constrained ILC component separation method
+to simulations of proposed CMB space missions (PIXIE, LiteBIRD, CORE, PICO).
+Our sky simulations include Galactic dust, Galactic synchrotron, Galactic
+free-free, thermal Sunyaev-Zeldovich effect, as well as primary CMB temperature
+and $\mu$-distortion anisotropies, the latter being added as correlated field.
+The Constrained ILC method allows us to null the CMB temperature anisotropies
+in the reconstructed $\mu$-map (and vice versa), in addition to mitigating the
+contaminations from astrophysical foregrounds and instrumental noise. We
+compute the cross-power spectrum between the reconstructed (CMB-free)
+$\mu$-distortion map and the ($\mu$-free) CMB temperature map, after foreground
+removal and component separation. Since the cross-power spectrum is
+proportional to the primordial non-Gaussianity parameter, $f_{\rm NL}$, on
+scales $k\simeq 740$ Mpc$^{-1}$, this allows us to derive $f_{\rm
+NL}$-detection limits for the aforementioned future CMB experiments. Our
+analysis shows that foregrounds degrade the theoretical detection limits (based
+mostly on instrumental noise) by more than one order of magnitude, with PICO
+standing the best chance at placing upper limits on scale-dependent
+non-Gaussianity. We also discuss the dependence of the constraints on the
+channel sensitivities and chosen bands. Like for $B$-mode polarization
+measurements, extended coverage at frequencies $\nu\lesssim 40\,{\rm GHz}$ and
+$\nu\gtrsim 400\,{\rm GHz}$ provides more leverage than increased channel
+sensitivity.",1802.10101v2
+2018-03-02,Multi-messenger constraints to the local emission of cosmic-ray electrons,"The data on the inclusive flux of cosmic positrons and electrons
+($e^++e^{-}$) have been recently collected from GeV to tens of TeV energies by
+several experiments with unprecedented precision. In addition, the Fermi-LAT
+Collaboration has provided a new energy spectrum for the upper bounds on the
+$e^++e^{-}$ dipole anisotropy. This observable can bring information on the
+emission from local Galactic sources, notably measured with high precision at
+radio frequencies. We develop a framework in which $e^-$ and $e^+$ measured at
+Earth from GeV up to tens of TeV energies have a composite origin. A dedicated
+analysis is deserved to Vela YZ and Cygnus Loop Supernova Remnants (SNRs), for
+which we consider two different models for the injection of $e^-$. We
+investigate the consistency of these models using the three physical
+observables: the radio flux from Vela YZ and Cygnus Loop at all the available
+frequencies, the $e^++e^-$ flux from five experiments from the GeV to tens of
+TeV energy, the $e^++e^-$ dipole anisotropy upper limits from 50 GeV to about 1
+TeV. We find that the radio flux for these nearby SNRs strongly constraints the
+properties of the injection electron spectrum, partially compatible with the
+looser constraints derived from the $e^+ + e^-$ flux data. We also perform a
+multi-wavelength multi-messenger analysis by fitting simultaneously the radio
+flux on Vela YZ and Cygnus Loop and the $e^+ + e^-$ flux, and checking the
+outputs against the $e^+ + e^-$ dipole anisotropy data. Remarkably, we find a
+model which is compatible with all the $e^++e^-$ flux data, the radio data for
+Vela YZ and Cygnus Loop, and with the anisotropy upper bounds. We show the
+severe constraints imposed by the most recent data on the $e^+ + e^-$ dipole
+anisotropy.",1803.01009v3
+2018-05-22,Exploring compensated isocurvature perturbations with CMB spectral distortion anisotropies,"We develop a linear perturbation theory for the spectral $y$-distortions of
+the cosmic microwave background (CMB). The $y$-distortions generated during the
+recombination epoch are usually negligible because the energy transfer due to
+the Compton scattering is strongly suppressed at that time, but they can be
+significant if there is a considerable amount of compensated isocurvature
+perturbation (CIP), which is not tightly constrained from the present CMB
+observations. The linear $y$-distortions explicitly depend on the baryon
+density fluctuations, therefore $y$ anisotropies can completely resolve the
+degeneracy between the baryon isocurvature perturbations and the cold dark
+matter ones. This novel method is free from lensing contaminations that can
+affect the previous approach to the CIPs based on the nonlinear modulation of
+the CMB anisotropies. We compute the cross correlation functions of the
+$y$-distortions with the CMB temperature and the $E$ mode polarization
+anisotropies. They are sensitive to the correlated CIPs parameterized by
+$f'\equiv\mathcal P_{\rm CIP\zeta}/\mathcal P_{\zeta \zeta}$ with $\mathcal
+P_{\zeta \zeta}$ and $\mathcal P_{\rm CIP\zeta}$ being the auto correlation of
+the adiabatic perturbations and the cross correlation between them and the
+CIPs. We investigate how well the $y$ anisotropies will constrain $f'$ in
+future observations such as those provided by a PIXIE-like and a PRISM-like
+survey, LiteBIRD and a cosmic variance limited (CVL) survey, taking into
+account the degradation in constraining power due to the presence of Sunyaev
+Zel'dovich effect from galaxy clusters. For example, our forecasts show that it
+is possible to achieve an upper limit of $f'< 2 \times 10^{5}$ at 68% C.L. with
+LiteBIRD, and $f'<2\times 10^{4}$ with CVL observations.",1805.08773v3
+2018-06-27,"Cosmic ray short burst observed with the Global Muon Detector Network (GMDN) on June 22, 2015","We analyze the short cosmic ray intensity increase (""cosmic ray burst"": CRB)
+on June 22, 2015 utilizing a global network of muon detectors and derive the
+global anisotropy of cosmic ray intensity and the density (i.e. the
+omnidirectional intensity) with 10-minute time resolution. We find that the CRB
+was caused by a local density maximum and an enhanced anisotropy of cosmic rays
+both of which appeared in association with Earth's crossing of the heliospheric
+current sheet (HCS). This enhanced anisotropy was normal to the HCS and
+consistent with a diamagnetic drift arising from the spatial gradient of cosmic
+ray density, which indicates that cosmic rays were drifting along the HCS from
+the north of Earth. We also find a significant anisotropy along the HCS,
+lasting a few hours after the HCS crossing, indicating that cosmic rays
+penetrated into the inner heliosphere along the HCS. Based on the latest
+geomagnetic field model, we quantitatively evaluate the reduction of the
+geomagnetic cut-off rigidity and the variation of the asymptotic viewing
+direction of cosmic rays due to a major geomagnetic storm which occurred during
+the CRB and conclude that the CRB is not caused by the geomagnetic storm, but
+by a rapid change in the cosmic ray anisotropy and density outside the
+magnetosphere.",1806.10601v1
+2018-08-27,Magic angle effects in a trigonal Mn(III)3 cluster: deconstruction of a single-molecule magnet,"We present angle-dependent high-frequency EPR studies on a single-crystal of
+a trigonal Mn3 cluster with an unusual structure in which the local magnetic
+easy-axes of the constituent Mn(III) ions are tilted significantly away from
+the molecular C3 axis towards the magic-angle of 54.7 degrees, resulting in an
+almost complete cancelation of the 2nd-order axial magnetic anisotropy
+associated with the ferromagnetically coupled total spin ST = 6 ground state.
+This contrasts the situation in many related Mn3 single-molecule magnets (SMMs)
+that have been studied intensively in the past, for which the local MnIII
+anisotropy tensors are reasonably parallel, resulting in substantial barriers
+to magnetization relaxation (Ueff = 30 to 35 cm 1) and magnetization blocking
+below about 2.5 K. The suppression of the 2nd-order anisotropy in the present
+case results in a situation in which the zero-field splitting (ZFS) of the ST =
+6 ground state is dominated by 4th- and higher-order interactions. This
+provides a unique opportunity to study in depth how molecular geometry
+influences these interactions that are responsible for quantum tunneling of
+magnetization in high-symmetry SMMs. Angle-dependent EPR measurements provide a
+full mapping of the molecular magneto-anisotropy. Meanwhile, irreducible tensor
+operator (ITO) methods are employed in order to obtain analytic expressions
+that directly relate molecular anisotropy to the microscopic physics, i.e., the
+ZFS tensors associated with the individual MnIII ions, their orientations, and
+the exchange coupling between the three spins. We find that the magic-angle
+tilting leads to a massive compression of the ST = 6 ground state energy level
+diagram and strong mixing between spin projection states. Although these
+characteristics are antagonistic to SMM behavior, they provide important
+insights into the physics of polynuclear molecular nanomagnets.",1808.08922v1
+2018-09-04,Dynamics of cardiac re-entry in micro-CT and serial histological sections based models of mammalian hearts,"Cardiac re-entry regime of self-organised abnormal synchronisation underlie
+dangerous arrhythmias and fatal fibrillation. Recent advances in the theory of
+dissipative vortices, experimental studies, and anatomically realistic computer
+simulations, elucidated the role of cardiac re-entry interaction with fine
+anatomical features in the heart, and anatomy induced drift. The fact that
+anatomy and structural anisotropy of the heart is consistent within a species
+suggested its possible functional effect on spontaneous drift of cardiac
+re-entry. A comparative study of the anatomy induced drift could be used in
+order to predict evolution of atrial arrhythmia, and improve low-voltage
+defibrillation protocols and ablation strategies. Here, in micro-CT based model
+of rat pulmonary vein wall, and in sheep atria models based on high resolution
+serial histological sections, we demonstrate effects of heart geometry and
+anisotropy on cardiac re-entry anatomy induced drift, its pinning to
+fluctuations of thickness in the layer. The data sets of sheep atria and rat
+pulmonary vein wall are incorporated into the BeatBox High Performance
+Computing simulation environment. Re-entry is initiated at prescribed locations
+in the spatially homogeneous mono-domain models of cardiac tissue. Excitation
+is described by FitzHugh-Nagumo kinetics. In the in-silico models, isotropic
+and anisotropic conduction show specific anatomy effects and the interplay
+between anatomy and anisotropy of the heart. The main objectives are to
+demonstrate the functional role of the species hearts geometry and anisotropy
+on cardiac re-entry anatomy induced drift. In case of the rat pulmonary vein
+wall with ~90 degree transmural fibre rotation, it is shown that the joint
+effect of the PV wall geometry and anisotropy turns a plane excitation wave
+into a re-entry pinned to a small fluctuation of thickness in the wall.",1809.01186v1
+2019-03-07,"Uniaxial anisotropy, intrinsic and extrinsic damping in Co$_{2}$FeSi Heusler alloy thin films","Ferromagnetic resonance (FMR) technique has been used to study the
+magnetization relaxation processes and magnetic anisotropy in two different
+series of the Co2FeSi (CFS) Heusler alloy thin films, deposited on the Si(111)
+substrate by UHV sputtering. While the CFS films of fixed (50 nm) thickness,
+deposited at different substrate temperatures (TS) ranging from room
+temperature (RT) to 600^C, constitute the series-I, the CFS films with
+thickness t varying from 12 nm to 100 nm and deposited at 550^C make up the
+series-II. In series-I, the CFS films deposited at TS = RT and 200^C are
+completely amorphous, the one at TS = 300^C is partially crystalline, and those
+at TS equal 450^C, 550^C and 600^C are completely crystalline with B2 order. By
+contrast, all the CFS films in series-II are in the fully-developed B2
+crystalline state. Irrespective of the strength of disorder and film thickness,
+angular variation of the resonance field in the film plane unambiguously
+establishes the presence of global in-plane uniaxial anisotropy. Angular
+variation of the linewidth in the film plane reveals that, in the CFS thin
+films of varying thickness, a crossover from the in-plane local four-fold
+symmetry (cubic anisotropy) to local two-fold symmetry (uniaxial anisotropy)
+occurs as t exceeds 50 nm. Gilbert damping parameter {\alpha} decreases
+monotonously from 0.047 to 0.0078 with decreasing disorder strength (increasing
+TS) and jumps from 0.008 for the CFS film with t = 50 nm to 0.024 for the film
+with t equal 75 nm. Such variations of {\alpha} with TS and t are understood in
+terms of the changes in the total (spin-up and spin-down) density of states at
+the Fermi level caused by the disorder and film thickness.",1903.02976v1
+2019-08-19,Effects of magnetic anisotropy on spin and thermal transports in classical antiferromagnets on the square lattice,"Transport properties of the classical antiferromagnetic XXZ model on the
+square lattice have been theoretically investigated, putting emphasis on how
+the occurrence of a phase transition is reflected in spin and thermal
+transports. As is well known, the anisotropy of the exchange interaction
+$\Delta\equiv J_z/J_x$ plays a role to control the universality class of the
+transition of the model, i.e., either a second-order transition at $T_N$ into a
+magnetically ordered state or the Kosterlitz-Thouless (KT) transition at
+$T_{KT}$, which respectively occur for the Ising-type ($\Delta >1$) and
+$XY$-type ($\Delta <1$) anisotropies, while for the isotropic Heisenberg case
+of $\Delta=1$, a phase transition does not occur at any finite temperature. It
+is found by means of the hybrid Monte-Carlo and spin-dynamics simulations that
+the spin current probes the difference in the ordering properties, while the
+thermal current does not. For the $XY$-type anisotropy, the longitudinal
+spin-current conductivity $\sigma^s_{xx}$ ($=\sigma^s_{yy}$) exhibits a
+divergence at $T_{KT}$ of the exponential form, $\sigma^s_{xx} \propto
+\exp\big[ B/\sqrt{T/T_{KT}-1 }\, \big]$ with $B={\cal O}(1)$, while for the
+Ising-type anisotropy, the temperature dependence of $\sigma^s_{xx}$ is almost
+monotonic without showing a clear anomaly at $T_{N}$ and such a monotonic
+behavior is also the case in the Heisenberg-type spin system. The significant
+enhancement of $\sigma^s_{xx}$ at $T_{KT}$ is found to be due to the
+exponential rapid growth of the spin-current-relaxation time toward $T_{KT}$,
+which can be understood as a manifestation of the topological nature of a
+vortex whose lifetime is expected to get longer toward $T_{KT}$. Possible
+experimental platforms for the spin-transport phenomena associated with the KT
+topological transition are discussed.",1908.06630v1
+2019-08-31,Spin-gapped magnets with weak anisotropies I: Constraints on the phase of the condensate wave function,"We study the thermodynamic properties of dimerized spin-gapped quantum
+magnets with and without exchange anisotropy (EA) and Dzyaloshinsky and Moriya
+(DM) anisotropies within the mean-field approximation (MFA). For this purpose
+we obtain the thermodynamic potential $\Omega$ of a triplon gas taking into
+account the strength of DM interaction up to second order. The minimization of
+$\Omega$ with respect to self-energies $\Sigma_n$ and $\Sigma_{an}$ yields the
+equation for $X_{1,2}=\Sigma_n\pm\Sigma_{an}-\mu$, which define the dispersion
+of quasiparticles $E_k=\sqrt{\epsilon_k+X_1}\sqrt{\epsilon_k+X_2}$ where
+$\epsilon_k$ is the bare dispersion of triplons. The minimization of $\Omega$
+with respect to the magnitude $\rho_0$ and the phase $\Theta$ of triplon
+condensate leads to coupled equations for $\rho_0$ and $\Theta$. We discuss the
+restrictions on $\rho_0$ and $\Theta$ imposed by these equations for systems
+with and without anisotropy. The requirement of dynamical stability conditions
+$(X_1>0, X_2>0)$ in equilibrium, as well as the Hugenholtz-Pines theorem,
+particularly for isotropic Bose condensate, impose certain conditions to the
+physical solutions of these equations. It is shown that the phase angle of a
+purely homogenous Bose-Einstein condensate (BEC) without any anisotropy may
+only take values $\Theta=\pi n $ (n=0,$\pm 1,\pm 2$...) while that of BEC with
+even a tiny DM interaction results in $\Theta=\pi/2+2\pi n$. In contrast to the
+widely used Hartree-Fock-Popov approximation, which allows arbitrary phase
+angle, our approach predicts that the phase angle may have only discrete
+values, while the phase of the wave function of the whole system remains
+arbitrary as expected. The consequences of this phase locking for interference
+of two Bose condensates and to their possible Josephson junction is studied.",1909.00281v3
+2019-10-03,Initial conditions of the universe: Decaying tensor modes,"Many models of the early universe predict that there should be primordial
+tensor perturbations. These leave an imprint into the temperature and
+polarisation anisotropies of the cosmic microwave background (CMB). The
+differential equation describing the primordial tensor perturbations is a
+second order differential equation and thus has two solutions. Canonically, the
+decaying solution of this equation in radiation domination is dropped as it
+diverges at early times and on superhorizon scales while it is then suppressed
+at late times. Furthermore, if there is an inflationary phase prior to the
+radiation domination phase, the amplitude of the decaying mode will also be
+highly suppressed as it enters the radiation phase, thus its effect will be
+negligible. In this study we remain agnostic to the early universe models
+describing pre-radiation domination physics and allow this mode to be present
+and see what effect it has on the CMB anisotropies. We find that the decaying
+mode, if normalised at the same time on subhorizon scales as the growing mode
+leaves an imprint on the CMB anisotropies that is identical to the growing
+mode. Contrary to expectation, on large scales both modes are poorly
+constrained for a scale invariant spectrum, and the apparent divergence of the
+decaying mode does not lead to a divergent physical observable. Quantitatively,
+the decaying mode can be more constrained both from temperature and
+polarisation anisotropies. We use a model independent, non-parametric, approach
+to constrain both of these primordial tensor perturbations using the
+temperature and polarisation anisotropies. We find that both modes are best
+constrained at the reionisation and recombination bumps and crucially, at the
+reionisation bump the decaying mode can be distinguished from the growing mode.",1910.01416v1
+2019-10-04,Giant perpendicular magnetic anisotropy in Ir/Co/Pt multilayers,"We have studied the magnetic properties of multilayers composed of
+ferromagnetic metal Co and heavy metals with strong spin orbit coupling (Pt and
+Ir). Multilayers with symmetric (ABA stacking) and asymmetric (ABC stacking)
+structures are grown to study the effect of broken structural inversion
+symmetry. We compare the perpendicular magnetic anisotropy (PMA) energy of
+symmetric Pt/Co/Pt, Ir/Co/Ir multilayers and asymmetric Pt/Co/Ir, Ir/Co/Pt
+multilayers. First, the interface contribution to the PMA is studied using the
+Co layer thickness dependence of the effective PMA energy. Comparison of the
+interfacial PMA between the Ir/Co/Pt, Pt/Co/Ir asymmetric structures and
+Pt/Co/Pt, Ir/Co/Ir symmetric structures indicate that the broken structural
+inversion symmetry induced PMA is small compared to the overall interfacial
+PMA. Second, we find the magnetic anisotropy field is significantly increased
+in multilayers when the ferromagnetic layers are antiferromagnetically coupled
+via interlayer exchange coupling (IEC). Macrospin model calculations can
+qualitatively account for the relation between the anisotropy field and the
+IEC. Among the structures studied, IEC is the largest for the asymmetric
+Ir/Co/Pt multilayers: the exchange coupling field exceeds 3 T and consequently,
+the anisotropy field approaches 10 T. Third, comparing the asymmetric Ir/Co/Pt
+and Pt/Co/Ir structures, we find the IEC and, to some extent, the interface PMA
+are stronger for the former than the latter. X-ray magnetic circular dichroism
+studies suggest that the proximity induced magnetization in Pt is larger for
+the Ir/Co/Pt multilayers than the inverted structure, which may partly account
+for the difference in the magnetic properties. These results show the intricate
+relation between PMA, IEC and the proximity induced magnetization that can be
+exploited to design artificial structures with unique magnetic characteristics.",1910.01777v2
+2020-02-12,"Formation of a fast ""lane"" for positional transition in a microparticle-suspended nematic liquid crystal cell","In this paper, based on the numerical calculation of total energy utilizing
+the Green's function method, we found that the external electric field applied
+to a microparticle-suspended nematic liquid crystal cell, if reaching a
+critical value, combined with its direction, surface anchoring feature and
+molecular dielectric anisotropy, is possible to create an anisotropic ""bubble""
+around the microparticle with a vertical fast ""lane"", in which the
+microparticle can, driven by the asymmetric buoyant force, vertically move
+swiftly from the cell's midplane to a new equilibrium position, triggering a
+positional transition discovered by the author previously. Such a new
+equilibrium position is decided via a competition between the buoyant force and
+the effective force built upon the microparticle by the elastic energy gradient
+along the ""lane"". The threshold value of external field, depends on thickness
+$L$ and Frank elastic constant $K$ and slightly on the microparticle size and
+density, in a Fr\'{e}edericksz-like manner, but by a factor. For a nematic
+liquid crystal cell with planar surface alignment, a bistable equilibrium
+structure for the transition is found when the direction of the applied
+electric field is (a) perpendicular to the two plates of the cell with positive
+molecular dielectric anisotropy, or (b) parallel to the two plates and the
+anchoring direction of the cell with negative molecular dielectric anisotropy.
+Except for the formation of a vertical fast ""lane"", when the electric field
+applied is parallel to both the two plates and perpendicular to the anchoring
+direction, the microparticle suspended in the nematic liquid crystal tends to
+be trapped in the midplane, regardless of the sign of the molecular dielectric
+anisotropy. Such phenomenon also occurs for negative molecular dielectric
+anisotropy while the external is applied perpendicular to the two plates.",2002.05084v1
+2020-04-10,Ion beam modification of magnetic tunnel junctions,"The impact of 400 keV $Ar^+$ ion irradiation on the magnetic and electrical
+properties of in-plane magnetized magnetic tunnel junction (MTJ) stacks was
+investigated by ferromagnetic resonance, vibrating sample magnetometry and
+current-in-plane tunneling techniques. The irradiation-induced changes of the
+magnetic anisotropy, coupling energies and tunnel magnetoresistance (TMR)
+exhibited a correlated dependence on the ion fluence, which allowed us to
+distinguish between two irradiation regimes. In the low-fluence regime, ${\Phi}
+< 10^{14} cm^{-2}$, the parameters required for having a functioning MTJ were
+preserved: the anisotropy of the FeCoB free layer (FL) was weakly modulated
+following a small decrease in the saturation magnetization $M_S$; the TMR
+decreased continuously; the interlayer exchange coupling (IEC) and the exchange
+bias (EB) decreased slightly. In the high-fluence regime, ${\Phi} > 10^{14}
+cm^{-2}$, the MTJ was rendered inoperative: the modulation of the FL anisotropy
+was strong, caused by a strong decrease in $M_S$, ascribed to a high degree of
+interface intermixing between the FL and the Ta capping; the EB and IEC were
+also lost, likely due to intermixing of the layers composing the synthetic
+antiferromagnet; and the TMR vanished due to the irradiation-induced
+deterioration of the MgO barrier and MgO/FeCoB interfaces. We demonstrate that
+the layers surrounding the FL play a decisive role in determining the trend of
+the magnetic anisotropy evolution resulting from the irradiation, and that an
+ion-fluence window exists where such a modulation of magnetic anisotropy can
+occur, while not losing the TMR or the magnetic configuration of the MTJ.",2004.05025v1
+2020-04-13,Intermittency and Ion Temperature-Anisotropy Instabilities: Simulation and Magnetosheath Observation,"Weakly collisional space plasmas are rarely in local thermal equilibrium and
+often exhibit non-Maxwellian electron and ion velocity distributions that lead
+to the growth of microinstabilities, that is, enhanced electric and magnetic
+fields at relatively short wavelengths. These instabilities play an active role
+in the evolution of space plasmas, as does ubiquitous broadband turbulence
+induced by turbulent structures. This study compares certain properties of a
+2.5 dimensional Particle-In-Cell (PIC) simulation for the forward cascade of
+Alfvenic turbulence in a collisionless plasma against the same properties of
+turbulence observed by the Magnetospheric Multiscale Mission spacecraft in the
+terrestrial magnetosheath. The PIC
+  simulation is of decaying turbulence which develops both coherent structures
+and anisotropic ion velocity distributions with the potential to drive kinetic
+scale instabilities. The uniform background magnetic field points perpendicular
+to the plane of the simulation. Growth rates are computed from linear theory
+using the ion temperature anisotropies and ion beta values for both the
+simulation and the observations. Both the simulation and the observations show
+that strong anisotropies and growth rates occur highly intermittently in the
+plasma, and the simulation further shows that such anisotropies preferentially
+occur near current sheets. This suggests that, though microinstabilities may
+affect the plasma globally , they act locally and develop in response to
+extreme temperature anisotropies generated by turbulent structures. Further
+studies will be necessary to understand why there is an apparent correlation
+between linear instability theory and strongly intermittent turbulence.",2004.06164v1
+2020-06-03,Thermodynamics and magnetism in the 2D-3D crossover of the Hubbard model,"The realization of antiferromagnetic (AF) correlations in ultracold fermionic
+atoms on an optical lattice is a significant achievement. Experiments have been
+carried out in one, two, and three dimensions, and have also studied
+anisotropic configurations with stronger tunneling in some lattice directions.
+Such anisotropy is relevant to the physics of cuprate superconductors and other
+strongly correlated materials. Moreover, this anisotropy might be harnessed to
+enhance AF order. Here we numerically investigate, using Determinant Quantum
+Monte Carlo, a simple realization of anisotropy in the 3D Hubbard model in
+which the tunneling between planes, $t_\perp$, is unequal to the intraplane
+tunneling $t$. This model interpolates between the three-dimensional isotropic
+($t_\perp = t$) and two-dimensional ($t_\perp =0$) systems. We show that at
+fixed interaction strength to tunneling ratio ($U/t$), anisotropy can enhance
+the magnetic structure factor relative to both 2D and 3D results. However, this
+enhancement occurs at interaction strengths below those for which the N\'eel
+temperature $T_{\rm N\acute{e}el}$ is largest, in such a way that the structure
+factor cannot be made to exceed its value in isotropic 3D systems at the
+optimal $U/t$. We characterize the 2D-3D crossover in terms of the magnetic
+structure factor, real space spin correlations, number of doubly-occupied
+sites, and thermodynamic observables. An interesting implication of our results
+stems from the entropy's dependence on anisotropy. As the system evolves from
+3D to 2D, the entropy at a fixed temperature increases. Correspondingly, at
+fixed entropy, the temperature will decrease going from 3D to 2D. This suggests
+a cooling protocol in which the dimensionality is adiabatically changed from 3D
+to 2D.",2006.02029v2
+2020-09-17,Metastability in graded and step like variation of field and anisotropy of the Blume-Capel ferromagnet,"The metastable behaviour of two dimensional anisotropic Blume-Capel
+ferromagnet, under the influence of graded and stepped like variations of
+magnetic field, has been investigated by extensive Monte Carlo simulation using
+Metropolis single spin flip algorithm. Starting from the initial perfectly
+ordered state, reversal of magnetisation has been studied in presence of the
+field. Metastable lifetime or the reversal time of magnetisation for the system
+having uniform anisotropy and in the presence of both graded and stepped field
+has been studied. Also the same has been explored for a {\it graded and stepped
+anisotropic system} in presence of a uniform field. Finite size effect is
+analyzed for the variation of reversal time with gradient of field ($G_h$) and
+a scaling relation $\langle \tau \rangle \sim L^{-\beta} f(G_h L^\alpha)$ is
+proposed. Spatial variation of density profile for the projection states (i.e.,
++1, 0 and -1) has also been studied at the moment of reversal of magnetisation.
+The spatial variation of the number of spin flips per site is studied. Motion
+of the interface (or domain wall) with the gradient of field and gradient of
+anisotropy are investigated and are found to follow the hyperbolic tangent like
+behaviours in both cases. Since, both the anisotropy and the applied field have
+significant impact on the metastable lifetime, an interesting competitive
+scenario is observed for a {\it graded anisotropic system in graded field} and
+a {\it stepped anisotropic system in stepped field}. A line of marginal
+competition has been found out for both the cases separating the regions of
+field dominated reversal and anisotropy dominated reversal. The decay of the
+metastable volume fraction was found to follow the Avrami's law. The mean
+reversal time was observed to decrease monotonically across the phase boundary
+of the ferro-para transition.",2009.08342v3
+2020-10-26,Insights into searches for anisotropies in the nanohertz gravitational-wave background,"Within the next several years pulsar timing arrays (PTAs) are positioned to
+detect the stochastic gravitational-wave background (GWB) likely produced by
+the collection of inspiralling super-massive black holes binaries, and
+potentially constrain some exotic physics. So far most of the pulsar timing
+data analysis has focused on the monopole of the GWB, assuming it is perfectly
+isotropic. The natural next step is to search for anisotropies in the GWB. In
+this paper, we use the recently developed PTA Fisher matrix to gain insights
+into optimal search strategies for GWB anisotropies. For concreteness, we apply
+our results to EPTA data, using realistic noise characteristics of its pulsars.
+We project the detectability of a GWB whose angular dependence is assumed to be
+a linear combination of predetermined maps, such as spherical harmonics or
+coarse pixels. We find that the GWB monopole is always statistically correlated
+with these maps, implying a loss of sensitivity to the monopole when searching
+simultaneously for anisotropies. We then derive the angular distributions of
+the GWB intensity to which a PTA is most sensitive, and illustrate how one may
+use these ""principal maps"" to approximately reconstruct the angular dependence
+of the GWB. Since the principal maps are neither perfectly anisotropic nor
+uncorrelated with the monopole, we also develop a frequentist criterion to
+specifically search for anisotropies in the GWB without any prior knowledge
+about their angular distribution. Lastly, we show how to recover existing EPTA
+results with our Fisher formalism, and clarify their meaning. The tools
+presented here will be valuable in guiding and optimizing the computationally
+demanding analyses of pulsar timing data.",2010.13958v2
+2021-04-06,Modulating Curie Temperature and Magnetic Anisotropy in Nanoscale Layered Cr_{2}Te_{3} Films: Implications for Room-Temperature Spintronics,"Nanoscale layered ferromagnets have demonstrated fascinating two-dimensional
+magnetism down to atomic layers, providing a peculiar playground of spin orders
+for investigating fundamental physics and spintronic applications. However,
+strategy for growing films with designed magnetic properties is not well
+established yet. Herein, we present a versatile method to control the Curie
+temperature (T_{C}) and magnetic anisotropy during growth of ultrathin
+Cr_{2}Te_{3} films. We demonstrate increase of the TC from 165 K to 310 K in
+sync with magnetic anisotropy switching from an out-of-plane orientation to an
+in-plane one, respectively, via controlling the Te source flux during film
+growth, leading to different c-lattice parameters while preserving the
+stoichiometries and thicknesses of the films. We attributed this modulation of
+magnetic anisotropy to the switching of the orbital magnetic moment, using
+X-ray magnetic circular dichroism analysis. We also inferred that different
+c-lattice constants might be responsible for the magnetic anisotropy change,
+supported by theoretical calculations. These findings emphasize the potential
+of ultrathin Cr_{2}Te_{3} films as candidates for developing room-temperature
+spintronics applications and similar growth strategies could be applicable to
+fabricate other nanoscale layered magnetic compounds.",2104.02224v1
+2021-05-22,Local origin of the strong field-space anisotropy in the magnetic phase diagrams of Ce$_{1-x}$La$_x$B$_6$ measured in a rotating magnetic field,"Cubic f-electron compounds commonly exhibit highly anisotropic magnetic phase
+diagrams consisting of multiple long-range ordered phases. Field-driven
+metamagnetic transitions between them may depend not only on the magnitude, but
+also on the direction of the applied magnetic field. Examples of such behavior
+are plentiful among rare-earth borides, such as RB$_6$ or RB$_{12}$ ($R$ = rare
+earth). In this work, for example, we use torque magnetometry to measure
+anisotropic field-angular phase diagrams of La-doped cerium hexaborides,
+Ce$_{1-x}$La$_x$B$_6$ ($x$ = 0, 0.18, 0.28, 0.5). One expects that
+field-directional anisotropy of phase transitions must be impossible to
+understand without knowing the magnetic structures of the corresponding
+competing phases and being able to evaluate their precise thermodynamic energy
+balance. However, this task is usually beyond the reach of available
+theoretical approaches, because the ordered phases can be noncollinear, possess
+large magnetic unit cells, involve higher-order multipoles of 4f ions rather
+than simple dipoles, or just lack sufficient microscopic characterization. Here
+we demonstrate that the anisotropy under field rotation can be qualitatively
+understood on a much more basic level of theory, just by considering the
+crystal-electric-field scheme of a pair of rare-earth ions in the lattice,
+coupled by a single nearest-neighbor exchange interaction. Transitions between
+different crystal-field ground states, calculated using this minimal model for
+the parent compound CeB6, possess field-directional anisotropy that strikingly
+resembles the experimental phase diagrams. This implies that the anisotropy of
+phase transitions is of local origin and is easier to describe than the ordered
+phases themselves.",2105.10694v2
+2021-09-02,Primordial tensor bispectra in $μ$-CMB cross-correlations,"Cross-correlations between Cosmic Microwave Background (CMB) temperature and
+polarization anisotropies and $\mu$-spectral distortions have been considered
+to measure (squeezed) primordial scalar bispectra in a range of scales
+inaccessible to primary CMB bispectra. In this work we address whether it is
+possible to constrain tensor non-Gaussianities with these cross-correlations.
+We find that only primordial tensor bispectra with statistical anisotropies
+leave distinct signatures, while isotropic tensor bispectra leave either
+vanishing or highly suppressed signatures. We discuss how the angular
+dependence of squeezed bispectra in terms of the short and long momenta
+determine the non-zero cross-correlations. We also discuss how these
+non-vanishing configurations are affected by the way in which primordial
+bispectra transform under parity. By employing the so-called BipoSH formalism
+to capture the observational effects of statistical anisotropies, we make
+Fisher-forecasts to assess the detection prospects from $\mu T$, $\mu E$ and
+$\mu B$ cross-correlations. Observing statistical anisotropies in squeezed
+$\langle \gamma \gamma \gamma\rangle$ and $\langle \gamma \gamma \zeta\rangle$
+bispectra is going to be challenging as the imprint of tensor perturbations on
+$\mu$-distortions is subdominant to scalar perturbations, therefore requiring a
+large, independent amplification of the effect of tensor perturbations in the
+$\mu$-epoch. In absence of such a mechanism, statistical anisotropies in
+squeezed $\langle \zeta \zeta \gamma\rangle$ bispectrum are the most relevant
+sources of $\mu T$, $\mu E$ and $\mu B$ cross-correlations. In particular, we
+point out that in anisotropic inflationary models where $\langle \zeta \zeta
+\zeta \rangle$ leaves potentially observable signatures in $\mu T$ and $\mu E$,
+the detection prospects of $\langle \zeta \zeta \gamma\rangle$ from $\mu B$ are
+enhanced.",2109.01095v3
+2021-11-30,Spin and valley ordering of fractional quantum Hall states in monolayer graphene,"We study spin and valley ordering in the quantum Hall fractions in monolayer
+graphene at Landau level filling factors $\nu_G=-2+n/3$ $(n=2,4,5)$. We use
+exact diagonalizations on the spherical as well as toroidal geometry by taking
+into account the effect of realistic anisotropies that break the spin/valley
+symmetry of the pure Coulomb interaction. We also use a variational method
+based on eigenstates of the fully $SU(4)$ symmetric limit. For all the
+fractions we study there are two-component states for which the competing
+phases are generalizations of those occurring at neutrality $\nu_G=0$. They are
+ferromagnetic, antiferromagnetic, charge-density wave and K\'ekul\'e phases,
+depending on the values of Ising or XY anisotropies in valley space. The
+varying spin-valley content of the states leads to ground state quantum numbers
+that are different from the $\nu_G=0$ case. For filling factor $\nu_G=-2+5/3$
+there is a parent state in the $SU(4)$ limit which has a flavor content
+$(1,1/3,1/3,0)$ where the two components that are one-third filled form a
+two-component singlet. The addition of anisotropies leads to the formation of
+new states that have no counterpart at $\nu_G=0$. While some of them are
+predicted by the variational approach, we find notably that negative Ising-like
+valley anisotropy leads to the formation of a state which is a singlet in both
+spin and valley space and lies beyond the reach of the variational method. Also
+fully spin polarized two-component states at $\nu=-2+4/3$ and $\nu=-2+5/3$
+display an emergent $SU(2)$ valley symmetry because they do not feel
+point-contact anisotropies. We discuss implications for current experiments
+concerning possible spin transitions.",2111.15453v1
+2022-02-21,Anisotropy of the magnetic and transport properties in EuZn$_2$As$_2$,"Several recent studies have shown that the anisotropy in the magnetic
+structure of \ECA\ plays a significant role in stabilizing the Weyl nodes. To
+investigate the relationship between magnetic anisotropy and Weyl physics, we
+present a comparative study between EuZn$_2$As$_2$ and EuCd$_2$As$_2$ that are
+isostructural but with different magnetic anisotropy. We performed structural
+analysis, electronic transport, and magnetization experiments on
+millimeter-sized single crystals of EuZn$_2$As$_2$, and compared the results to
+those of EuCd$_2$As$_2$. By combining the first principle calculations and
+neutron diffraction experiment, we identify the magnetic ground state of
+EuZn$_2$As$_2$ as A-type antiferromagnetic order with a transition temperature
+($T_\mathrm{N}$ = 19.6 K) twice that of EuCd$_2$As$_2$. Like EuCd$_2$As$_2$,
+the negative magnetoresistance of EuZn$_2$As$_2$ is observed after suppressing
+the resistivity peak at $T_\mathrm{N}$ with increasing fields. However, the
+anisotropy in both transport and magnetization are much reduced in
+EuZn$_2$As$_2$. The difference could be ascribed to the weaker spin-orbit
+coupling, more localized $d$-orbitals, and a larger contribution from the Eu
+$s$-orbitals in the zinc compound, as suggested by the electronic band
+calculations. The same band structure effect could be also responsible for the
+observation of a smaller non-linear anomalous Hall effect in EuZn$_2$As$_2$
+compared to EuCd$_2$As$_2$.",2202.09963v1
+2022-08-31,A Heating Mechanism via Magnetic Pumping in the Intracluster Medium,"Turbulence driven by AGN activity, cluster mergers and galaxy motion
+constitutes an attractive energy source for heating the intracluster medium
+(ICM). How this energy dissipates into the ICM plasma remains unclear, given
+its low collisionality and high magnetization (precluding viscous heating by
+Coulomb processes). Kunz et al. 2011 proposed a viable heating mechanism based
+on the anisotropy of the plasma pressure (gyroviscous heating) under ICM
+conditions. The present paper builds upon that work and shows that particles
+can be gyroviscously heated by large-scale turbulent fluctuations via magnetic
+pumping. We study how the anisotropy evolves under a range of forcing
+frequencies, what waves and instabilities are generated and demonstrate that
+the particle distribution function acquires a high energy tail. For this, we
+perform particle-in-cell simulations where we periodically vary the mean
+magnetic field $\textbf{B}(t)$. When $\textbf{B}(t)$ grows (dwindles), a
+pressure anisotropy $P_{\perp}>P_{\parallel}$ ($P_{\perp}< P_{\parallel}$)
+builds up ($P_{\perp}$ and $P_{\parallel}$ are, respectively, the pressures
+perpendicular and parallel to $\textbf{B}(t)$). These pressure anisotropies
+excite mirror ($P_{\perp}>P_{\parallel}$) and oblique firehose
+($P_{\parallel}>P_{\perp}$) instabilities, which trap and scatter the
+particles, limiting the anisotropy and providing a channel to heat the plasma.
+The efficiency of this mechanism depends on the frequency of the large-scale
+turbulent fluctuations and the efficiency of the scattering the instabilities
+provide in their nonlinear stage. We provide a simplified analytical heating
+model that captures the phenomenology involved. Our results show that this
+process can be relevant in dissipating and distributing turbulent energy at
+kinetic scales in the ICM.",2209.00019v1
+2022-09-26,On the scaling and anisotropy of two subranges in the inertial range of solar wind turbulence,"Intermittency and anisotropy are two important aspects of plasma turbulence,
+which the solar wind provides a natural laboratory to investigate. However,
+their forms and nature are still under debate, making it difficult to achieve a
+consensus in the theoretical interpretation. Here, we perform higher-order
+statistics for the observations in the fast solar wind at 1.48 au obtained by
+Ulysses and in the slow solar wind at 0.17 au obtained by Parker Solar Probe
+(PSP). We find that two subranges clearly exist in the inertial range and they
+present distinct features with regard to the intermittency and anisotropy. The
+subrange 1 with smaller scale has a multifractal scaling with the second index
+$\xi(2) \sim 2/3$ and the subrange 2 with larger scale is also multifractal but
+with $\xi(2) \sim 1/2$. The break between two subranges locates at the same
+spatial scale for both Ulysses and PSP observations. Subrange 1 is multifractal
+in the direction perpendicular to the local magnetic field with $\xi_{\perp}(2)
+\sim 2/3$ and seems to be monoscaling in the parallel direction with
+$\xi_{\parallel}(2) \sim 1$. Subrange 2 is multifractal in both parallel and
+perpendicular directions with $\xi_{\perp}(2) \sim 1/2$ and $\xi_{\parallel}(2)
+\sim 2/3$. Both subrange 1 and subrange 2 present power and wavevector
+anisotropies. The distinct features of two subranges suggest that a transition
+from weak to strong turbulence may occur and the spatial scale of the break may
+not evolve with the solar wind expansion. These new results update our
+knowledge of the inertial range and provide strong observational constraints on
+the understanding of intermittency and anisotropy in solar wind turbulence.",2209.12409v1
+2023-05-13,Temperature dependence of magnetic anisotropy and domain wall tuning in BaTiO3(111)/CoFeB multiferroics,"Artificial multiferroics consist of two types of ferroic materials, typically
+a ferroelectric and ferromagnet, often coupled interfacially by
+magnetostriction induced by the lattice elongations in the ferroelectric. In
+BaTiO3 the magnitude of strain induced by these elongations is heavily
+temperature dependent, varying greatly between each of the polar crystal phases
+and exerting a huge influence over the properties of a coupled magnetic film.
+Here we demonstrate that temperature, and thus strain, is an effective means of
+controlling the magnetic anisotropy in BaTiO3(111)/CoFeB heterostructures. We
+investigate the three polar phases of BaTiO3: tetragonal (T) at room
+temperature, orthorhombic (O) below 280 K and rhombohedral (R) below 190 K,
+across a total range of 77 K to 420 K. We find two distinct responses; a
+step-like change in the anisotropy across the low-temperature phase
+transitions, and a sharp high-temperature reduction around the ferroelectric
+Curie temperature, measured from hard axis hysteresis loops. Using our
+measurements of this anisotropy strength we are then able to show by
+micromagnetic simulation the behaviour of all possible magnetic domain wall
+states and determine their scaling as a function of temperature. The most
+significant changes occur in the head-to-head domain wall states, with a
+maximum change of 210 nm predicted across the entire range effectively doubling
+the size of the domain wall as compared to room temperature. Notably, similar
+changes are seen for both high and low temperatures which suggest different
+routes for potential control of magnetic anisotropy and elastically pinned
+magnetic domain walls.",2305.07879v1
+2023-05-28,What can be learnt from UHECR anisotropies observations Paper II: intermediate-scale anisotropies,"Analysing the available data relative to the anisotropies of the
+ultra-high-energy cosmic rays (UHECR) at intermediate angular scales, we
+examine to what extent they can be used to constrain the origin of these
+particles, and what could be gained from a new generation of observatories with
+increased exposure. We simulate realistic UHECR sky maps for a wide range of
+scenarios, with the assumption that the distribution of UHECR sources follows
+that of matter in the Universe, also considering possible biases. We produce
+numerous datasets on which we apply similar analyses as those recently used by
+the Auger and TA collaborations. We find that: i) the investigated scenarios
+can easily account for the significance of the anisotropies reported by Auger
+and TA; ii) the direction in which the maximum flux excess is found in the
+Auger data differs from where it is found in most of our simulations; iii) for
+datasets simulated with the same astrophysical scenario, the significance with
+which the isotropy hypothesis is rejected through the Auger likelihood analysis
+can be largest either when ""all galaxies"" or when ""starburst"" galaxies are used
+to model the signal, depending on which GMF model is used; iv) the study of the
+energy evolution of the anisotropy patterns can provide new insight about the
+origin of UHECRs; v) the direction in which the most significant flux excess is
+found in the Auger dataset above 8 EeV appears to essentially disappear in the
+dataset above 32 EeV; vi) this appears to be very uncommon in our simulations,
+which could point to a failure of some generic assumption in the investigated
+scenarios, such as the predominance of a unique type of sources in the flux
+above the ankle, with essentially the same composition and spectrum; vii) a
+meaningful measurement of their energy evolution, from 10 EeV to the highest
+energies, will require a significant increase in statistics.",2305.17811v1
+2023-06-01,Impact of magnetic anisotropy on the magnon Hanle effect in $α$-Fe$_2$O$_3$,"In easy-plane antiferromagnets, the nature of the elementary excitations of
+the spin system is captured by the precession of the magnon pseudospin around
+its equilibrium pseudofield, manifesting itself in the magnon Hanle effect.
+Here, we investigate the impact of growth-induced changes in the magnetic
+anisotropy on this effect in the antiferromagnetic insulator
+$\alpha$-Fe$_2$O$_3$ (hematite). To this end, we compare the structural,
+magnetic, and magnon-based spin transport properties of $\alpha$-Fe$_2$O$_3$
+films with different thicknesses grown by pulsed laser deposition in molecular
+and atomic oxygen atmospheres. While in films grown with molecular oxygen a
+spin-reorientation transition (Morin transition) is absent down to $10\,$K, we
+observe a Morin transition for those grown by atomic-oxygen-assisted
+deposition, indicating a change in magnetic anisotropy. Interestingly, even for
+a $19\,$nm thin $\alpha$-Fe$_2$O$_3$ film grown with atomic oxygen we still
+detect a Morin transition at $125\,$K. We characterize the magnon Hanle effect
+in these $\alpha$-Fe$_2$O$_3$ films via all-electrical magnon transport
+measurements. The films grown with atomic oxygen show a markedly different
+magnon spin signal from those grown in molecular oxygen atmospheres. Most
+importantly, the maximum magnon Hanle signal is significantly enhanced and the
+Hanle peak is shifted to lower magnetic field values for films grown with
+atomic oxygen. These observations suggest a change of magnetic anisotropy for
+$\alpha$-Fe$_2$O$_3$ films fabricated by atomic-oxygen-assisted deposition
+resulting in an increased oxygen content in these films. Our findings provide
+new insights into the possibility to fine-tune the magnetic anisotropy in
+$\alpha$-Fe$_2$O$_3$ and thereby to engineer the magnon Hanle effect.",2306.00375v1
+2023-09-01,f-mode oscillations of anisotropic neutron stars in full general relativity,"We investigate f-mode oscillations of static anisotropic stable neutron stars
+within the framework of full general relativity. We present equations governing
+unperturbed stellar structures and oscillations with an ansatz to account for
+the anisotropy. We solve those equations for two different equations of states.
+We see that, moderately anisotropic neutron stars with the tangential pressure
+larger than the radial pressure can give more massive neutron stars than the
+isotropic or very anisotropic ones. We find that the frequency of the f-mode
+exhibits a linear relationship with the square root of the average density of
+the stars and the slope of the fit depends on the anisotropic strength. For any
+given value of the anisotropic strength, the frequency increases with the
+increase of the mass of the neutron star, linearly for lower masses, and
+rapidly at higher masses. However, this non-linear rise in the frequency with
+the mass is not prominent when the radial pressure is larger than the
+tangential pressure. For a fixed value of a small mass, higher anisotropy leads
+to a larger value of the frequency, but when the fixed mass is above a
+threshold value, higher anisotropy leads to a smaller value of the frequency.
+The nature of the variation in the frequency with the change in the anisotropic
+strength is similar for the two equations of state, but for a fixed mass and
+the same amount of the anisotropy, the softer equations of state gives higher
+frequency. We also find that the damping time of the f-mode oscillation
+decreases as the mass of the neutron star increases for all values of the
+anisotropic strength. For a fixed mass of the neutron star and for the same
+amount of the anisotropy, the value of the damping time is lower for the softer
+equation of state, but the nature of the variation in the damping time with the
+change in the anisotropic strength is similar.",2309.00439v2
+2023-10-02,Control of the magnetic anisotropy in multi-repeat Pt/Co/Al heterostructures using magneto-ionic gating,"Controlling magnetic properties through the application of an electric field
+is a significant challenge in modern nanomagnetism. In this study, we
+investigate the magneto-ionic control of magnetic anisotropy in the topmost Co
+layer in Ta/Pt/[Co/Al/Pt]$_n$/Co/Al/AlO$_\text{x}$ multilayer stacks comprising
+$n +1$ Co layers and its impact on the magnetic properties of the multilayers.
+We demonstrate that the perpendicular magnetic anisotropy can be reversibly
+quenched through gate-driven oxidation of the intermediary Al layer between Co
+and AlO$_\text{x}$, enabling dynamic control of the magnetic layers
+contributing to the out-of-plane remanence - varying between $n$ and $n +1$.
+For multilayer configurations with $n = 2$ and $n = 4$, we observe reversible
+and non-volatile additions of 1/3 and 1/5, respectively, to the anomalous Hall
+effect amplitude based on the applied gate voltage. Magnetic imaging reveals
+that the gate-induced spin-reorientation transition occurs through the
+propagation of a single 90$^{\circ}$ magnetic domain wall separating the
+perpendicular and in-plane anisotropy states. In the 5-repetition multilayer,
+the modification leads to a doubling of the period of the magnetic domains at
+remanence. These results demonstrate that the magneto-ionic control of the
+anisotropy of a single magnetic layer can be used to control the magnetic
+properties of coupled multilayer systems, extending beyond the gating effects
+on a single magnetic layer.",2310.01623v1
+2023-12-19,Magnetism of noncolinear amorphous DyCo3 and TbCo3 thin films,"The magnetization of amorphous DyCo3 and TbCo3 is studied by magnetometry,
+anomalous Hall effect and magneto-optic Kerr effect to understand the
+temperature-dependent magnetic structure. A square magnetic hysteresis loop
+with perpendicular magnetic anisotropy and coercivity that reaches 3.5 T in the
+vicinity of the compensation temperature is seen in thin films. An anhysteretic
+soft component, seen in the magnetization of some films but not in their Hall
+or Kerr loops is an artefact due to sputter-deposition on the sides of the
+substrate. The temperature-dependence of the net rare earth moment from 4-300K
+is deduced, using the cobalt moment in amorphous YxCo1-x. The single-ion
+anisotropy of the quadrupole moments of the 4f atoms in the randomly-oriented
+local electrostatic field gradient overcomes their exchange coupling to the
+cobalt subnetwork, resulting in a sperimagnetic ground state where spins of the
+noncollinear rare-earth subnetwork are modelled by a distribution of rare earth
+moments within a cone whose axis is antiparallel to the ferromagnetic axis z of
+the cobalt subnetwork. The reduced magnetization (Jz)/J at T=0 is calculated
+from an atomic Hamiltonian as a function of the ratio of anisotropy to exchange
+energy per rare-earth atom for a range of angles between the local anisotropy
+axis and -z and then averaged over all directions in a hemisphere. The
+experimental and calculated values of (J-z)/J are close to 0.7 at low
+temperature for both Dy and Tb. On increasing temperature, the magnitude of the
+rare earth moment and the local random anisotropy that creates the cone are
+reduced; the cone closes and the structure approaches collinear ferrimagnetism
+well above ambient temperature. An asymmetric spin flop of the exchange-coupled
+subnetworks appears in the vicinity of the magnetization compensation
+temperatures of 175K for amorphous Dy0.25Co0.75 and 200 K for amorphous TbCo3.",2312.12602v1
+2013-07-22,"CLASH-VLT: The mass, velocity-anisotropy, and pseudo-phase-space density profiles of the z=0.44 galaxy cluster MACS 1206.2-0847","We use an unprecedented data-set of about 600 redshifts for cluster members,
+obtained as part of a VLT/VIMOS large programme, to constrain the mass profile
+of the z=0.44 cluster MACS J1206.2-0847 over the radial range 0-5 Mpc (0-2.5
+virial radii) using the MAMPOSSt and Caustic methods. We then add external
+constraints from our previous gravitational lensing analysis. We invert the
+Jeans equation to obtain the velocity-anisotropy profiles of cluster members.
+With the mass-density and velocity-anisotropy profiles we then obtain the first
+determination of a cluster pseudo-phase-space density profile. The kinematics
+and lensing determinations of the cluster mass profile are in excellent
+agreement. This is very well fitted by a NFW model with mass M200=(1.4 +- 0.2)
+10^15 Msun and concentration c200=6 +- 1, only slightly higher than theoretical
+expectations. Other mass profile models also provide acceptable fits to our
+data, of (slightly) lower (Burkert, Hernquist, and Softened Isothermal Sphere)
+or comparable (Einasto) quality than NFW. The velocity anisotropy profiles of
+the passive and star-forming cluster members are similar, close to isotropic
+near the center and increasingly radial outside. Passive cluster members follow
+extremely well the theoretical expectations for the pseudo-phase-space density
+profile and the relation between the slope of the mass-density profile and the
+velocity anisotropy. Star-forming cluster members show marginal deviations from
+theoretical expectations. This is the most accurate determination of a cluster
+mass profile out to a radius of 5 Mpc, and the only determination of the
+velocity-anisotropy and pseudo-phase-space density profiles of both passive and
+star-forming galaxies for an individual cluster [abridged]",1307.5867v2
+1993-05-29,Reionization and cosmic microwave background distortions: a complete treatment of second order Compton scattering,"The ionization history of the universe provides a major source of ambiguity
+in constraining cosmological models using small angular scale microwave
+background anisotropies. To clarify these issues, we consider a complete
+treatment of Compton scattering to second order, an approach which may be
+applicable to other astrophysical situations. We find that only the ${\cal O}
+(v)$ Doppler effect, and the ${\cal O} (v\delta)$ Vishniac effect are important
+for recent last scattering epochs; the ${\cal O} (v^2)$ Doppler effect is not
+significant on any angular scale, and other higher-order effects are completely
+negligible. However the ${\cal O}(v^2)$ effect does lead to \Cy\ distortions,
+which although generally below current constraints, set an unavoidable minimum
+level in reionization models. We consider the small-angle approximation for the
+Vishniac effect in detail, and show several improvements over previous
+treatments, particularly for low $\Omega_0$. For standard cold dark matter
+models, the effect of reionization is to redistribute the anisotropies to
+arcminute scales; late reionization leads to partially erased primary
+fluctuations and a secondary contribution of comparable magnitude. Using recent
+anisotropy limits from the ATCA experiment, we set new constraints on baryonic
+dark matter models. Stronger constraints are imposed (in second order) upon
+models with higher Hubble constant, steeper $n$, and higher density. These
+limits depend on the specific ionization history assumed, but the factor gained
+by lowering the ionization fraction is generally small, and may be tested by
+currently-planned",9305038v1
+1993-10-28,Analysis of Small Scale MBR Anisotropy in the Presence of Foreground Contamination,"Many of the current round of experiments searching for anisotropies in the
+MBR are confronting the problem of how to disentangle the cosmic signal from
+contamination due to galactic and intergalactic foreground sources. Here we
+show how commonly used likelihood function techniques can be generalized to
+account for foreground. Specifically we set some restrictions on the spectrum
+of foreground contamination but allow the amplitude to vary arbitrarily. The
+likelihood function thus generalized gives reasonable limits on the MBR
+anisotropy which, in some cases, are not much less restrictive than what one
+would get from more detailed modeling of the foreground. Furthermore, the
+likelihood function is exactly the same as one would obtain by simply
+projecting out foreground contamination and just looking at the reduced data
+set. We apply this generalized analysis to the recent medium angle data sets of
+ACME-HEMT and MAX. The resulting analysis constrains the one free parameter in
+the standard cold dark matter theory to be Q=18_-5^+8 microK. This best fit
+value, although in striking agreement with the normalization from COBE, is not
+a very good fit, with an overall chi^2/ degree of freedom =208/168. We also
+argue against three commonly used methods of dealing with foreground: (i)
+ignoring it completely; (ii) subtracting off a best fit foreground and treating
+the residuals as if uncontaminated; and (iii) culling data which appears to be
+contaminated by foreground.",9310048v1
+1993-12-24,Anisotropies of Cosmic Background Radiation from a Local Collapse,"We present an exact solution of the anisotropies of cosmic background
+radiation (CBR) from a local collapse described by a spherical over-dense
+region embedded in a flat universe, with the emphasis on the relationship
+between the dipole $(\Delta {\sf T}/{\sf T})_d$ and the quadrupole $(\Delta
+{\sf T}/{\sf T})_q$ anisotropy. This result has been used to examine the
+kinematic quadrupole correction $(\Delta {\sf T}/{\sf T})_q=(\Delta {\sf
+T}/{\sf T})_d^2/2$, which is usually applied to remove the contamination of the
+quadrupole produced by local density inhomogeneities when finding the cosmic
+amplitude of the quadrupole at the surface of last scattering. We have found
+that the quadrupole of local collapse origin cannot always be approximately
+described by the kinematic quadrupole. Our numerical result shows that the
+difference between the kinematic and local quadrupoles depends on the size and
+matter density in the peculiar field, and the position of the observer. For a
+given dipole, the local quadrupole can be different from the kinematic
+quadrupole by a factor as large as 3. Therefore, the kinematic quadrupole
+correction remains an uncertain factor in the determination of the amplitude of
+a cosmic quadrupole. Nevertheless, a preliminary analysis shows that this
+uncertainty might not dramatically change the cosmological origin of the
+COBE-DMR's quadrupole, unless a huge peculiar gravitational field is assumed.",9312057v1
+1994-04-28,Measurements of Anisotropy in the Cosmic Microwave Background Radiation at Degree Angular Scales Near the Stars Sigma Hercules and Iota Draconis,"We present results from two four-frequency observations centered near the
+stars Sigma Hercules and Iota Draconis during the fourth flight of the
+Millimeter-wave Anisotropy eXperiment (MAX). The observations were made of 6 x
+0.6-degree strips of the sky with 1.4-degree peak to peak sinusoidal chop in
+all bands. The FWHM beam sizes were 0.55+/-0.05 degrees at 3.5 cm-1 and a
+0.75+/-0.05 degrees at 6, 9, and 14 cm-1. Significant correlated structures
+were observed at 3.5, 6 and 9 cm-1. The spectra of these signals are
+inconsistent with thermal emission from known interstellar dust populations.
+The extrapolated amplitudes of synchrotron and free-free emission are too small
+to account for the amplitude of the observed structures. If the observed
+structures are attributed to CMB anisotropy with a Gaussian autocorrelation
+function and a coherence angle of 25', then the most probable values are
+DT/TCMB = (3.1 +1.7-1.3) x 10^-5 for the Sigma Hercules scan, and DT/TCMB =
+(3.3 +/- 1.1) x 10^-5 for the Iota Draconis scan (95% confidence upper and
+lower limits). Finally a comparison of all six MAX scans is presented.",9404072v3
+1994-11-08,The Anisotropy in the Cosmic Microwave Background At Degree Angular Scales,"We detect anisotropy in the cosmic microwave background (CMB) at degree
+angular scales and confirm a previous detection reported by Wollack et al.
+(1993). The root-mean-squared amplitude of the fluctuations is $44^{+13}_{-7}
+\mu$K. This may be expressed as the square root of the angular power spectrum
+in a band of multipoles between $l_{eff}=69^{+29}_{-22}$. We find $\delta T_l =
+\sqrt{l(2l+1)<|a_l^m|^2>/4\pi} = 42^{+12}_{-7} \mu$K. The measured spectral
+index of the fluctuations is consistent with zero, the value expected for the
+CMB. The spectral index corresponding to Galactic free-free emission, the most
+likely foreground contaminant, is rejected at approximately $3\sigma$.
+  The analysis is based on three independent data sets. The first, taken in
+1993, spans the 26 - 36 GHz frequency range with three frequency bands; the
+second was taken with the same radiometer as the first but during an
+independent observing campaign in 1994; and the third, also take in 1994, spans
+the 36-46 GHz range in three bands. For each telescope position and radiometer
+channel, the drifts in the instrument offset are $\le 4~\mu$K/day over a period
+of one month. The dependence of the inferred anisotropy on the calibration and
+data editing is addressed.",9411035v1
+1994-12-07,Cosmic Background Anisotropies in CDM Cosmology,"Cosmic microwave background (CMB) anisotropies and density fluctuations are
+calculated for flat cold dark matter (CDM) models with a wide range of
+parameters, i.e., $\Omega_0, h$ and $\Omega_B$ for both standard recombination
+and various epochs of reionization. Tables of the power spectrum of CMB
+anisotropies in the form of $C_\ell$'s as a function of $\ell$ are presented.
+Although the Harrison-Zeldovich initial spectrum is assumed in these tables, we
+present simple approximations for obtaining the $C_\ell$'s corresponding to a
+tilted spectrum from those with a Harrison-Zeldovich spectrum. The $\sigma_8$
+values are obtained for the matter density spectrum, with $\sigma(10^\circ)$,
+fixed $Q_{rms-PS}$ and COBE DMR 2 year normalizations. Simple modifications of
+the fitting formula of the density transfer function which are applicable for
+models with high baryon density are given. By using both numerical results and
+these fitting formulae, we calculate the relation between $\sigma_8$ and
+$Q_{rms-PS}$, and find good agreement. Velocity fields are also calculated.",9412025v2
+1995-01-31,Simple Analytical Methods for Computing the Gravity-Wave Contribution to the Cosmic Background Radiation Anisotropy,"We present two simple analytical methods for computing the gravity wave
+contribution to the cosmic background radiation (CBR) anisotropy in
+inflationary models; one method uses a time-dependent transfer function, the
+other method uses an approximate gravity-wave mode function which is a simple
+combination of the lowest order spherical Bessel functions. We compare the CBR
+anisotropy tensor multipole spectrum computed using our methods with the
+previous result of the highly accurate numerical method, the ``Boltzmann''
+method. Our time-dependent transfer function is more accurate than the
+time-independent transfer function found by Turner, White, and Lidsey; however,
+we find that the transfer function method is only good for $l \la 120$. Using
+our approximate gravity-wave mode function, we obtain much better accuracy; the
+tensor multipole spectrum we find differs by less than 2\% for $l \la 50$, less
+than 10\% for $l \la 120$, and less than 20\% for $l \leq 300$ from the
+``Boltzmann'' result. Our approximate graviton mode function should be quite
+useful in studying tensor perturbations from inflationary models.",9501116v2
+1995-08-18,MSAM1-94: Repeated Measurement of Medium-Scale Anisotropy in the Cosmic Microwave Background Radiation,"The second flight of the Medium Scale Anisotropy Measurement (MSAM1-94)
+observed the same field as the first flight (MSAM1-92) to confirm our earlier
+measurement of cosmic microwave background radiation (CMBR) anisotropy. This
+instrument chops a 30\arcmin\ beam in a 3 position pattern with a throw of
+$\pm40\arcmin$, and simultaneously measures single and double differenced sky
+signals. We observe in four spectral channels centered at 5.6, 9.0, 16.5, and
+22.5~\icm, providing sensitivity to the peak of the CMBR and to thermal
+emission from interstellar dust. The dust component correlates well with the
+\IRAS\ 100~\micron\ map. The CMBR observations in our double difference channel
+correlate well with the earlier observations, but the single difference channel
+shows some discrepancies. We obtain a detection of fluctuations in the MSAM1-94
+dataset that match CMBR in our spectral bands of $\Delta T/T =
+1.9^{+1.3}_{-0.7}\times 10^{-5}$ (90\% confidence interval, including
+calibration uncertainty) for total rms Gaussian fluctuations with correlation
+angle 0\fdg3, using the double difference demodulation.",9508087v1
+1995-10-08,The Nonlinear Redshift Space Power Spectrum: Omega from Redshift Surveys,"We examine the anisotropies in the power spectrum by the mapping of real to
+redshift space. Using the Zel'dovich approximation, we obtain an analytic
+expression for the nonlinear redshift space power spectrum in the distant
+observer limit. For a given unbiased galaxy distribution in redshift space, the
+anisotropies in the power spectrum depend on the parameter $f(\Omega)\approx
+\Omega^{0.6}$, where $\Omega$ is the density parameter. We quantify these
+anisotropies by the ratio, $R$, of the quadrupole to monopole angular moments
+of the power spectrum. In contrast to linear theory, the Zel'dovich
+approximation predicts a decline in $R$ with decreasing scale. This departure
+from linear theory is due to nonlinear dynamics and not a result of incoherent
+random velocities. The rate of decline depends strongly on $\Omega$ and the
+initial power spectrum. However, we find a {\it universal} relation between the
+quantity $R/R_{lin}$ (where $R_{lin}$ the linear theory value of $R$) and the
+dimensionless variable $k/k_{nl}$, where $k_{nl}$ is a wavenumber determined by
+the scale of nonlinear structures. The universal relation is in good agreement
+with a large N-body simulation. This universal relation greatly extends the
+scales over which redshift distortions can be used as a probe of $\Omega$. A
+preliminary application to the 1.2 Jy IRAS yields $\Omega\sim 0.4$ if IRAS
+galaxies are unbiased.",9510049v1
+1995-12-21,Implications of the Background Radiation for Cosmic Structure Formation,"The CMB is a remarkably distortionless blackbody, and this strongly
+constrains the amount of energy that can have been injected at high redshift,
+thereby limiting the role that hydrodynamical amplification can have played in
+cosmic structure formation. The current data on primary anisotropies (those
+calculated using linear response theory) provide very strong support for the
+gravitational instability theory and encouraging support that the initial
+fluctuation spectrum was not far off the scale invariant form that inflation
+(and defect) models prefer. By itself, the (low resolution) 4-year DMR data
+allow relatively precise \sigma_8 normalization factors for density fluctuation
+spectra and rough information on the large scale slope of the anisotropy power,
+thereby focusing our attention on a relatively narrow set of viable models.
+Useful formulae relating the DMR bandpower to \sigma_8 and post-inflation
+scalar and tensor power spectra measures are given. Smaller angle data are
+consistent with these models, and will soon be powerful enough to strongly
+select among the possibilities, although there remains much room for surprises.
+In spite of foregrounds, future high resolution experiments should be able to
+allow precise determination of many combinations of the cosmological parameters
+that define large scale structure formation theories: mode
+(adiabatic/isocurvature, gravity wave content), shape functions, amplitudes,
+and various mean energy densities. Secondary anisotropies arising from
+nonlinear structures will be invaluable probes of shorter-distance aspects of
+structure formation theories.",9512142v2
+1995-12-26,CMB Anisotropies and Theories of the Early Universe,"I present recent work aimed at showing how currently competing theories of
+the early universe leave their imprint on the temperature anisotropies of the
+CMB radiation. We consider the 3-point correlation function, as well as the
+inherent theoretical uncertainties associated with it, for which we derive
+explicit analytic formulae. We apply them in the study of non-Gaussian features
+that arise on large scales in the framework of both inflationary and
+topological defects models. For inflation, we develop a perturbative analysis
+for the study of spatial correlations in the inflaton in the context of the
+stochastic approach to inflation. We also include an analysis of a particular
+geometry, the so-called `collapsed' 3-point function, in the case of post
+recombination integrated effects, arising generically whenever the mildly non
+linear growth of perturbations is taken into account. We also devote a part of
+the thesis to the study of recently proposed analytic models of topological
+defects, and implement them in the analysis of both the CMB excess kurtosis
+(for cosmic strings) and the CMB collapsed 3-point function and skewness (for
+textures). Lastly, we present a study of the CMB anisotropies on the degree
+angular scale in the framework of the global texture scenario, and show the
+relevant features that arise; among these, the Doppler peaks.",9512161v1
+1996-04-01,The Signature of a Correlation between $>10^{19}{\rm eV}$ Cosmic Ray Sources and Large Scale Structure,"We analyze the anisotropy signature expected if the high energy (above
+$10^{19}$eV) cosmic ray (CR) sources are extra-Galactic and trace the
+distribution of luminous matter on large scales. We investigate the dependence
+of the anisotropy on both the relative bias between the CR sources and the
+galaxy distribution and on the (unknown) intrinsic CR source density. We find
+that the expected anisotropy associated with the large scale structure (LSS)
+should be detected once the number of CR events observed above $10^{19}{\rm
+eV}$ is increased by a factor of $\sim10$. This would require $\sim30$
+observation-years with existing experiments, but less then $1$ year with the
+proposed $\sim5000\ {\rm km}^2$ Auger detectors. We find that the recently
+reported concentration of the Haverah Park CR events towards the super-galactic
+plane is not consistent with the known LSS. If real, the Haverah Park result
+suggests that the CR sources are much more concentrated towards the
+super-galactic plane than the known LSS. Our results are not sensitive to the
+number density of CR sources. We show that once the number of detected events
+is increased by a factor of $\sim10$, the number density would be strongly
+constrained by considering the probability for having repeating sources.",9604005v1
+1996-05-15,The Analytical Distribution Function of Anisotropic Hernquist+Hernquist Models,"The analytical phase-space distribution function (DF) of spherical
+self--consistent galaxy (or cluster) models, embedded in a dark matter halo,
+where both density distributions follow the Hernquist profile, with different
+total masses and core radii (hereafter called HH models), is presented. The
+concentration and the amount of the stellar and dark matter distributions are
+described by four parameters: the mass and core radius of the {\it reference}
+component, and two dimensionless parameters describing the mass and core radius
+of the {\it halo} component. A variable amount of orbital anisotropy is allowed
+in both components, following the widely used parameterization of
+Osipkov-Merritt. An important case is obtained for a null core radius of the
+halo, corresponding to the presence of a central black hole (BH). It is proved
+that globally isotropic HH models are consistent for any mass ratio and core
+radii ratio, even in the case of a central BH. In this last case the analytical
+expression for a lower limit of the anisotropy radius of the host system as a
+function of the BH mass is given. In the particular case of global isotropy the
+stability of HH models is proved, and the stability of radially anisotropic HH
+models is briefly discussed. The expression derived for the DF is useful for
+understanding the relations between anisotropy, density shape and external
+potential well in a consistent stellar system, and to produce initial
+conditions for N-body simulations of two-component galaxies or galaxy clusters.",9605084v1
+1996-05-17,Quantum fluctuations and CMB anisotropies in one-bubble open inflation models,"We first develop a method to calculate a complete set of mode functions which
+describe the quantum fluctuations generated in one-bubble open inflation
+models. We consider two classes of models. One is a single scalar field model
+proposed by Bucher, Goldhaber and Turok and by us as an example of the open
+inflation scinario, and the other is a two-field model such as the
+``supernatural'' inflation proposed by Linde and Mezhlumian. In both cases we
+assume the difference in the vacuum energy density between inside and outside
+the bubble is negligible. There are two kinds of mode functions. One kind has
+usual continuous spectrum and the other has discrete spectrum with
+characteristic wavelengths exceeding the spatial curvature scale. The latter
+can be further devided into two classes in terms of its origin. One is called
+the de Sitter super-curvature mode, which arises due to the global spacetime
+structure of de Sitter space, and the other is due to fluctuations of the
+bubble wall. We calculate the spectrum of quantum fluctuations in these models
+and evaluate the resulting large angular scale CMB anisotropies. We find there
+are ranges of model parameters that are consistent with observed CMB
+anisotropies.",9605103v1
+1996-10-15,The Theoretical Agenda in CMB Research,"The terrain that theorists cover in this CMB golden age is described. We
+ponder early universe physics in quest of the fluctuation generator. We extoll
+the virtues of inflation and defects. We transport fields, matter and radiation
+into the linear (primary anisotropies) and nonlinear (secondary anisotropies)
+regimes. We validate our linear codes to deliver accurate predictions for
+experimentalists to shoot at. We struggle at the computing edge to push our
+nonlinear simulations from only illustrative to fully predictive. We are now
+phenomenologists, optimizing statistical techniques for extracting truths and
+their errors from current and future experiments. We begin to clean
+foregrounds. We join CMB experimental teams. We combine the CMB with large
+scale structure, galaxy and other cosmological observations in search of
+current concordance. The brave use all topical data. Others carefully craft
+their prior probabilities to downweight data sets. We are always unbiased. We
+declare theories sick, dead, ugly. Sometimes we cure them, resurrect them,
+rarely beautify them. Our goal is to understand how all cosmic structure we see
+arose and what the Universe is made of, and to use this to discover the laws of
+ultrahigh energy physics. Theorists are humble, without hubris.",9610119v1
+1996-11-05,Signatures of Stellar Reionization of the Universe,"The high ionization level and universal metallicity (1% solar) of the
+intergalactic gas at redshifts z<5 implies that nonlinear structure had started
+to form in the universe at earlier times than we currently probe. In Cold Dark
+Matter (CDM) cosmologies, the first generation of baryonic objects emerges at
+redshifts z=10-50. Here we examine the observable consequences of the
+possibility that an early generation of stars reionized the universe and
+resulted in the observed metallicity of the Lyman-alpha forest. Forthcoming
+microwave anisotropy experiments will be sensitive to the damping of
+anisotropies caused by scattering off free electrons from the reionization
+epoch. For a large range of CDM models with a Scalo stellar mass function, we
+find that reionization occurs at a redshift z>10 and damps the amplitude of
+anisotropies on angular scales <10 degrees by a detectable amount, of order
+10-25%. However, reionization is substantially delayed if the initial stellar
+mass function transformed most of the baryons into low mass stars. In this
+case, the mass fraction of pre-galactic stars could be constrained from the
+statistics of microlensing events in galactic halos or along lines of sight to
+quasars. Deep infrared imaging with future space telescopes (such as SIRTF or
+the Next Generation Space Telescope) will be able to detect bright star
+clusters at z>5. The cumulative Bremsstrahlung emission from these star
+clusters yields a measurable distortion to the spectrum of the microwave
+background.",9611028v2
+1997-02-21,An Upper Limit to Arcminute Scale Anisotropy in the Cosmic Microwave Background Radiation at 142 GHz,"We present limits to anisotropies in the cosmic microwave background
+radiation (CMB) at angular scales of a few arcminutes. The observations were
+made at a frequency of 142 GHz using a 6-element bolometer array (the
+Sunyaev-Zel'dovich Infrared Experiment) at the Caltech Submillimeter
+Observatory. Two patches of sky, each approximately 36'x4' and free of known
+sources, were observed for a total of 6-8 hours each, resulting in
+approximately 80 independent 1.7' full-width half-maximum pixels. Each pixel is
+observed with both a dual-beam and a triple-beam chop, with a sensitivity per
+pixel of 90-150 uK in each chop. These data have been analyzed using maximum
+likelihood techniques by assuming a gaussian autocorrelation function for the
+distribution of CMB fluctuations on the sky. We set an upper limit of Delta T/T
+<= 2.1 x 10^{-5} (95% confidence) for a coherence angle to the fluctuations of
+1.1. These limits are comparable to the best limits obtained from
+centimeter-wavelength observations on similar angular scales but have the
+advantage that the contribution from known point sources is negligible at these
+frequencies. They are the most sensitive millimeter-wavelength limits for
+coherence angles <= 3'. The results are also considered in the context of
+secondary sources of anisotropy, specifically the Sunyaev-Zel'dovich effect
+from galaxy clusters.",9702196v1
+1997-04-24,Evidence for Brightness-Dependent Anisotropy of Gamma Ray Bursts and Its Galactic Intepretation,"We show that the brighter gamma-ray bursts (GRBs) in the BATSE 3B catalog
+concentrate slightly toward the Galactic plane and center, suggesting that at
+least some bursts originate within the Galaxy. To develop an interpretation of
+this brightness-dependent anisotropy, we consider GRBs distributed in a thick
+disk centered on the Galaxy. As an approximation to the true luminosity
+distribution, we divide bursts into two distinct luminosity classes. Most
+bursts originate from low-luminosity, nearby sources while the relatively few
+high-luminosity sources trace the shape of the thick disk. We find that
+characteristic disk dimensions as small as 20 kpc in thickness and 30 kpc in
+radial extent can match the observed brightness-dependent anisotropy as well as
+the number-flux distribution; these dimensions are smaller than previously
+considered viable. For bursts distributed in a disk of these compact
+dimensions, the low-luminosity sources must have peak powers of $\lapprox
+5\times 10^{40}$ erg s$^{-1}$ and rate densities of $\gapprox 5\times 10^{-3}$
+yr$^{-1}$ kpc$^{-3}$. The high-luminosity sources must have a peak luminosity
+of $\simeq 10^{42}$ erg s$^{-1}$ but their rate density need be only 5% or less
+than that of the low-luminosity sources. If the Andromeda Galaxy contained a
+similar population of high-luminosity sources, their peak gamma-ray fluxes
+would be less than $\sim 0.1$ s$^{-1}$ cm$^{-2}$, making their detection
+problematic. Statistical analyses of the gamma-ray burst events obtained since
+the compilation of the 3B catalog will determine whether the thick-disk
+interpretation is preferred over the isotropic one.",9704244v1
+1998-03-04,Moving Gravitational Lenses: imprints on the CMB,"With the new generation of instruments for Cosmic Microwave Background (CMB)
+observations aiming at an accuracy level of a few percent in the measurement of
+the angular power spectrum of the anisotropies, the study of the contributions
+due to secondary effects has gained impetus. Furthermore, a reinvestigation of
+the main secondary effects is crucial in order to predict and quantify their
+effects on the CMB and the errors that they induce in the measurements. In this
+paper, we investigate the contribution, to the CMB, of secondary anisotropies
+induced by the transverse motions of clusters of galaxies. This effect is
+similar to the Kaiser-Stebbins effect. In order to address this problem, we
+model the gravitational potential well of an individual structure using the
+Navarro, Frenk & White profile. We generalise the effect of one structure to a
+population of objects predicted using the Press-Schechter formalism. We
+simulate maps of these secondary fluctuations, compute the angular power
+spectrum and derive the average contributions for three cosmological models. We
+then investigate a simple method to separate this new contribution from the
+primary anisotropies and from the main secondary effect, the Sunyaev-Zel'dovich
+kinetic effect from the lensing clusters.",9803040v1
+1998-04-04,Computing CMB Anisotropy in Compact Hyperbolic Spaces,"The measurements of CMB anisotropy have opened up a window for probing the
+global topology of the universe on length scales comparable to and beyond the
+Hubble radius. For compact topologies, the two main effects on the CMB are: (1)
+the breaking of statistical isotropy in characteristic patterns determined by
+the photon geodesic structure of the manifold and (2) an infrared cutoff in the
+power spectrum of perturbations imposed by the finite spatial extent. We
+present a completely general scheme using the regularized method of images for
+calculating CMB anisotropy in models with nontrivial topology, and apply it to
+the computationally challenging compact hyperbolic topologies. This new
+technique eliminates the need for the difficult task of spatial eigenmode
+decomposition on these spaces. We estimate a Bayesian probability for a
+selection of models by confronting the theoretical pixel-pixel temperature
+correlation function with the COBE-DMR data. Our results demonstrate that
+strong constraints on compactness arise: if the universe is small compared to
+the `horizon' size, correlations appear in the maps that are irreconcilable
+with the observations. If the universe is of comparable size, the likelihood
+function is very dependent upon orientation of the manifold wrt the sky. While
+most orientations may be strongly ruled out, it sometimes happens that for a
+specific orientation the predicted correlation patterns are preferred over the
+conventional infinite models.",9804041v2
+1998-05-24,"Brown Dwarfs, White Knights and Demons","This paper investigates the hypothesis that the lensing objects towards the
+Large Magellanic Cloud (LMC) are brown dwarfs by analysing the effects of
+velocity anisotropy on the inferred microlensing masses. To reduce the masses,
+the transverse velocity of the lenses with respect to the microlensing tube
+must be minimised. In the outer halo, radial anisotropy is best for doing this;
+closer to the solar circle, azimuthal anisotropy is best. By using a constraint
+on the total kinetic energy of the tracer population from the Jeans equations,
+the microlensing mass is minimised over orientations of the velocity dispersion
+tensor. This minimum mass is about a tenth of a solar mass, which lies above
+the hydrogen burning limit. This demonstrates explicitly that populations of
+brown dwarfs with smoothly decreasing densities and dynamically mixed velocity
+distributions cannot be responsible for the microlensing events. Brown dwarfs
+are no white knights! There is one caveat. If there are demons sitting on the
+microlensing tube, they can drop brown dwarfs so as to reproduce the
+microlensing data-set exactly. Such a distribution is not smooth and does not
+give well-mixed velocities in phase space. It is a permissible solution only if
+the outer halo is dynamically young and lumpy. In such a case, theorists cannot
+rule out brown dwarfs. Only exorcists can!",9805304v1
+1998-06-06,Study of Broad Scale Anisotropy of Cosmic Ray Arrival Directions from $2\times 10^{17} eV$ to $10^{20} eV$ from Fly's Eye Data,"We report results on the broad scale anisotropy of cosmic ray arrival
+directions in the energy rage from $2 \times 10^{17} eV$ to $10^{20} eV$. The
+data was taken by the Fly's Eye detector in both monocular and stereo modes of
+operation. We look for dependence on galactic latitude or supergalactic
+latitude by fitting the data to a Wdowczyk and Wolfendale plane enhancement
+function and a N-S gradient functional form. We report a small but
+statistically significant galactic plane enhancement in the energy range
+between $2\times 10^{17}eV$ and $3.2 \times 10^{18} eV$. The probability that
+this anisotropy is due to fluctuations of an isotropic distribution is less
+than 0.06%. The most significant galactic plane enhancement factor $f_{E} =
+0.104 \pm 0.036$ is in the energy range $0.4-1.0 \times 10^{18} eV$. No
+statistically significant evidence for a N-S gradient is found. There is no
+sign of significant deviation from isotropic background when the data is
+analyzed in terms of supergalactic latitude distributions",9806096v1
+1998-06-27,Observationally Determining the Properties of Dark Matter,"Determining the properties of the dark components of the universe remains one
+of the outstanding challenges in cosmology. We explore how upcoming CMB
+anisotropy measurements, galaxy power spectrum data, and supernova (SN)
+distance measurements can observationally constrain their gravitational
+properties with minimal assumptions on the theoretical side. SN observations
+currently suggest the existence of dark matter with an exotic equation of state
+p/rho < -1/3 that accelerates the expansion of the universe. When combined with
+CMB anisotropy measurements, SN or galaxy survey data can in principle
+determine the equation of state and density of this component separately,
+regardless of their value, as long as the universe is spatially flat. Combining
+these pairs creates a sharp consistency check. If p/rho > -1/2, then the
+clustering behavior (sound speed) of the dark component can be determined so as
+to test the scalar-field ``quintessence'' hypothesis. If the exotic matter
+turns out instead to be simply a cosmological constant (p/rho = -1), the
+combination of CMB and galaxy survey data should provide a significant
+detection of the remaining dark matter, the neutrino background radiation
+(NBR). The gross effect of its density or temperature on the expansion rate is
+ill-constrained as it is can be mimicked by a change in the matter density.
+However, anisotropies of the NBR break this degeneracy and should be detectable
+by upcoming experiments.",9806362v1
+1998-07-29,ARGO CMB Anisotropy Measurement Constraints on Open and Flat-Lambda CDM Cosmogonies,"We use data from the ARGO cosmic microwave background (CMB) anisotropy
+experiment to constrain cosmogonies. We account for the ARGO beamwidth and
+calibration uncertainties, and marginalize over the offset removed from the
+data. Our derived amplitudes of the CMB anisotropy detected by the ARGO
+experiment are smaller than those derived previously.
+  We consider open and spatially-flat-Lambda cold dark matter cosmogonies, with
+clustered-mass density parameter Omega_0 in the range 0.1-1, baryonic-mass
+density parameter Omega_B in the range (0.005-0.029)h^{-2}, and age of the
+universe t_0 in the range (10--20) Gyr. Marginalizing over all parameters but
+Omega_0, the ARGO data favors an open (spatially-flat-Lambda) model with
+Omega_0= 0.23 (0.1). However, these numerical values are model dependent.
+  At the 2 sigma confidence level model normalizations deduced from the ARGO
+data are consistent with those drawn from the UCSB South Pole 1994, MAX 4+5,
+White Dish, and SuZIE data sets. The ARGO open model normalizations are also
+consistent with those deduced from the DMR data. However, for most
+spatially-flat-Lambda models the DMR normalizations are more than 2 sigma above
+the ARGO ones.",9807298v1
+1998-08-01,Implications of SCUBA observations for the Planck Surveyor,"We investigate the implications for the Planck Surveyor of the recent
+sub-millimetre number counts obtained using the SCUBA camera. Since it observes
+at the same frequency as one of the higher frequency science channels on
+Planck, SCUBA can provide constraints on the point-source contribution to the
+CMB angular power spectrum, which require no extrapolation in frequency. We
+have calculated the two-point function of these sub-millimetre sources, using a
+Poisson model normalized to the observed counts. While the current data are
+uncertain, under reasonable assumptions the point-source contribution to the
+anisotropy is comparable to the noise in the 353GHz channel. The clustering of
+these sources is currently unknown, however if they cluster like the z~3
+Lyman-break galaxies their signal would be larger than the primary anisotropy
+signal on scales smaller than about 10 arcmin. We expect the intensity of these
+sources to decrease for wavelengths longward of 850 microns. At the next lowest
+Planck frequency, 217GHz, the contribution from both the clustered and Poisson
+terms are dramatically reduced. Hence we do not expect these sources to
+seriously affect Planck's main science goal, the determination of the
+primordial anisotropy power spectrum. Rather, the potential determination of
+the distribution of sub-mm sources is a further piece of cosmology that Planck
+may be able to tackle.",9808003v3
+1999-04-29,1+3 Covariant Cosmic Microwave Background anisotropies II: The almost - Friedmann Lemaitre model,"This is the second of a series of papers extending the 1+3 covariant and
+gauge invariant treatment of kinetic theory to an examination of Cosmic
+Microwave Background temperature anisotropies arising from inhomogeneities in
+the early universe. The first paper dealt with algebraic issues.
+  Here we derive the mode form of the integrated Boltzmann equations, first,
+giving a covariant version of the standard derivation using the mode recursion
+relations, second, demonstrating the link to the multipole divergence equations
+and finally various analytic ways of solving the resulting equations are
+discussed.
+  A general integral form of solution is obtained for the equations with
+Thomson scattering. The covariant Friedmann-Lemaitre multipole form of the
+transport equations are found using the covariant and gauge-invariant
+generalization of the Peebles and Yu expansion in Thompson scattering time. The
+dispersion relations and damping scale are then obtained from the covariant
+approach. The equations are integrated to give the covariant and
+gauge-invariant equivalent of the canonical scalar sourced anisotropies.
+  We carry out a simple treatment of the matter dominated free-streaming
+projection, slow decoupling, and tight-coupling cases, with the aim both giving
+a unified transparent derivation of this range of results and clarifying the
+connection between the more usual approaches (for example that of Hu and
+Sugiyama) and the treatment for scalar perturbations (for example the treatment
+of Challinor and Lasenby).",9904408v2
+1999-06-22,The origin and formation of cuspy density profiles through violent relaxation of stellar systems,"It is shown that the cuspy density distributions observed in the cores of
+elliptical galaxies can be realized by dissipationless gravitational collapse.
+The initial models consist of power-law density spheres such as $\rho\propto
+r^{-1}$ with anisotropic velocity dispersions. Collapse simulations are carried
+out by integrating the collisionless Boltzmann equation directly, on the
+assumption of spherical symmetry. From the results obtained, the extent of
+constant density cores, formed through violent relaxation, decreases as the
+velocity anisotropy increases radially, and practically disappears for
+extremely radially anisotropic models. As a result, the relaxed density
+distributions become more cuspy with increasing radial velocity anisotropy. It
+is thus concluded that the velocity anisotropy could be a key ingredient for
+the formation of density cusps in a dissipationless collapse picture. The
+velocity dispersions increase with radius in the cores according to the nearly
+power-law density distributions. The power-law index, $n$, of the density
+profiles, defined as $\rho\propto r^{-n}$, changes from $n\approx 2.1$ at
+intermediate radii, to a shallower power than $n\approx 2.1$ toward the centre.
+This density bend can be explained from our postulated local phase-space
+constraint that the phase-space density accessible to the relaxed state is
+determined at each radius by the maximum phase-space density of the initial
+state.",9906354v1
+1999-07-05,Mean magnetic field generation in sheared rotators,"A generalized mean magnetic field induction equation for differential
+rotators is derived, including a compressibility, and the anisotropy induced on
+the turbulent quantities from the mean magnetic field itself and a mean
+velocity shear. Derivations of the mean field equations often do not emphasize
+that there must be anisotropy and inhomogeneity in the turbulence for mean
+field growth. The anisotropy from shear is the source of a term involving the
+product of the mean velocity gradient and the cross-helicity correlation of the
+isotropic parts of the fluctuating velocity and magnetic field,
+$\lb{\bfv}\cdot{\bfb}\rb^{(0)}$. The full mean field equations are derived to
+linear order in mean fields, but it is also shown that the cross-helicity term
+survives to all orders in the velocity shear. This cross-helicity term can
+obviate the need for a pre-existing seed mean magnetic field for mean field
+growth: though a fluctuating seed field is necessary for a non-vanishing
+cross-helicity, the term can produce linear (in time) mean field growth of the
+toroidal field from zero mean field. After one vertical diffusion time, the
+cross-helicity term becomes sub-dominant and dynamo exponential
+amplification/sustenance of the mean field can subsequently ensue. The
+cross-helicity term should produce odd symmetry in the mean magnetic field, in
+contrast to the usually favored even modes of the dynamo amplification in
+sheared discs. This may be important for the observed mean field geometries of
+spiral galaxies. The strength of the mean seed field provided by the cross-
+helicity depends linearly on the magnitude of the cross-helicity.",9907061v3
+1999-08-26,Data Processing and Compression of Cosmic Microwave Background Anisotropies on Board the PLANCK Satellite,"We present a simple way of coding and compressing the data on board the
+Planck instruments (HFI and LFI) to address the problem of the on board data
+reduction. This is a critical issue in the Planck mission. The total
+information that can be downloaded to Earth is severely limited by the
+telemetry allocation. This limitation could reduce the amount of diagnostics
+sent on the stability of the radiometers and, as a consequence, curb the final
+sensitivity of the CMB anisotropy maps. Our proposal to address this problem
+consists in taking differences of consecutive circles at a given sky pointing.
+To a good approximation, these differences are independent of the external
+signal, and are dominated by thermal (white) instrumental noise. Using
+simulations and analytical predictions we show that high compression rates,
+$c_r \simeq 10$, can be obtained with minor or zero loss of CMB sensitivity.
+Possible effects of digital distortion are also analized. The proposed scheme
+allows for flexibility to optimize the relation with other critical aspects of
+the mission. Thus, this study constitutes an important step towards a more
+realistic modeling of the final sensitivity of the CMB temperature anisotropy
+maps.",9908289v1
+2000-02-21,Properties of spherical galaxies and clusters with an NFW density profile,"Using the standard dynamical theory of spherical systems, we calculate the
+properties of spherical galaxies and clusters whose density profiles obey the
+universal form first obtained in high resolution cosmological N-body
+simulations by Navarro, Frenk & White. We adopt three models for the internal
+kinematics: isotropic velocities, constant anisotropy and increasingly radial
+Osipkov-Merritt anisotropy. Analytical solutions are found for the radial
+dependence of the mass, gravitational potential, velocity dispersion, energy
+and virial ratio and we test their variability with the concentration parameter
+describing the density profile and amount of velocity anisotropy. We also
+compute structural parameters, such as half-mass radius, effective radius and
+various measures of concentration. Finally, we derive projected quantities, the
+surface mass density and line-of-sight as well as aperture velocity dispersion,
+all of which can be directly applied in observational tests of current
+scenarios of structure formation. On the mass scales of galaxies, if constant
+mass-to-light is assumed, the NFW surface density profile is found to fit well
+Hubble-Reynolds laws. It is also well fitted by Sersic R^(1/m) laws, for m ~ 3,
+but in a much narrower range of m and with much larger effective radii than are
+observed. Assuming in turn reasonable values of the effective radius, the mass
+density profiles imply a mass-to-light ratio that increases outwards at all
+radii.",0002395v2
+2000-02-24,An Australia telescope survey for CMB anisotropies,"We have surveyed six distinct `empty fields' using the Australia Telescope
+Compact Array in an ultra-compact configuration with the aim of imaging, with a
+high brightness sensitivity, any arcmin-scale brightness-temperature
+anisotropies in the background radio sky. The six well-separated regions were
+observed at a frequency of 8.7 GHz and the survey regions were limited by the
+ATCA primary beams which have a full width at half maximum of 6 arcmin at this
+frequency; all fields were observed with a resolution of 2 arcmin and an rms
+thermal noise of 24 microJy/beam. After subtracting foreground confusion
+detected in higher resolution images of the fields, residual fluctuations in
+Stokes I images are consistent with the expectations from thermal noise and
+weaker (unidentified) foreground sources; the Stokes Q and U images are
+consistent with expectations from thermal noise.
+  Within the sensitivity of our observations, we have no reason to believe that
+there are any Sunyaev-Zeldovich holes in the microwave sky surveyed. Assuming
+Gaussian-form CMB anisotropy with a `flat' spectrum, we derive 95 per cent
+confidence upper limits of Q_flat < 10--11 microK in polarized intensity and
+Q_flat < 25 microK in total intensity. The ATCA filter function peaks at l=4700
+and has half maximum values at l=3350 and 6050.",0002467v1
+2000-04-28,A Flat Universe from High-Resolution Maps of the Cosmic Microwave Background Radiation,"The blackbody radiation left over from the Big Bang has been transformed by
+the expansion of the Universe into the nearly isotropic 2.73K Cosmic Microwave
+Background. Tiny inhomogeneities in the early Universe left their imprint on
+the microwave background in the form of small anisotropies in its temperature.
+These anisotropies contain information about basic cosmological parameters,
+particularly the total energy density and curvature of the universe. Here we
+report the first images of resolved structure in the microwave background
+anisotropies over a significant part of the sky. Maps at four frequencies
+clearly distinguish the microwave background from foreground emission. We
+compute the angular power spectrum of the microwave background, and find a peak
+at Legendre multipole $\ell_{peak}=(197 \pm 6)$, with an amplitude
+$DT_{200}=(69 \pm 8)\mu K$. This is consistent with that expected for cold dark
+matter models in a flat (euclidean) Universe, as favoured by standard
+inflationary scenarios.",0004404v1
+2000-05-22,Exhaustive Study of Cosmic Microwave Background Anisotropies in Quintessential Scenarios,"Recent high precision measurements of the CMB anisotropies performed by the
+BOOMERanG and MAXIMA-1 experiments provide an unmatched set of data allowing to
+probe different cosmological models. Among these scenarios, motivated by the
+recent measurements of the luminosity distance versus redshift relation for
+type Ia supernovae, is the quintessence hypothesis. It consists in assuming
+that the acceleration of the Universe is due to a scalar field whose final
+evolution is insensitive to the initial conditions. Within this framework we
+investigate the cosmological perturbations for two well-motivated potentials:
+the Ratra-Peebles and the SUGRA tracking potentials. We show that the solutions
+of the perturbed equations possess an attractor and that, as a consequence, the
+insensitivity to the initial conditions is preserved at the perturbed level.
+Then, we study the predictions of these two models for structure formation and
+CMB anisotropies and investigate the general features of the multipole moments
+in the presence of quintessence. We also compare the CMB multipoles calculated
+with the help of a full Boltzmann code with the BOOMERanG and MAXIMA-1 data. We
+pay special attention to the location of the second peak and demonstrate that
+it significantly differs from the location obtained in the cosmological
+constant case. Finally, we argue that the SUGRA potential is compatible with
+all the recent data with a standard values of the cosmological parameters. In
+particular, it fits the MAXIMA-1 data better than a cosmological constant or
+the Ratra-Peebles potential.",0005428v1
+2000-07-13,Cyclotron Line Features from Near-Critical Fields II: on the Effect of Anisotropic Radiation Fields,"We assess the impact of radiation anisotropy on the line shapes that result
+from relativistic magnetic Compton scattering in the low-density/high-field
+regime. A Monte Carlo implementation of radiation transport allows for spatial
+diffusion of photons in arbitrary geometries and accounts for relativistic
+angular redistribution. The cross section includes natural line widths and
+photon ""spawning"" from up to fourth harmonic photons. In our first paper we
+noted that even if the photon injection is isotropic a strongly anisotropic
+radiation field rapidly ensues. We now investigate the angular distribution of
+cyclotron spectra emerging from an internally irradiated magnetized plasma with
+a prescribed global geometry (either cylindrical or plane parallel) and the
+effects of anisotropic photon injection on the line shapes. Varying the input
+angular distribution permits a better understanding of the line formation
+process in more realistic scenarios where the radiative mechanisms are
+influenced by the intrinsic anisotropy of the field and by moderate
+relativistic beaming. In general, the line features are most pronounced along
+the directions of the anisotropic continuum injection and tend to be weakened
+in other directions, relative to the line features resulting from an isotropic
+continuum injection. We find that the enhancements at the line wings of the
+fundamental, which appear prominantly in the case of isotropic continuum
+injection, are strongly suppressed along the direction of anisotropy in the
+case of beamed continuum injection, regardless of geometry or beaming pattern.",0007191v1
+2000-08-02,Constraints on Cosmological Anisotropy out to z=1 from Supernovae Ia,"A combined sample of 79 high and low redshift supernovae Ia (SNe) is used to
+set constraints on the degree of anisotropy in the Universe out to $z\simeq1$.
+First we derive the global most probable values of matter density $\Omega_M $,
+the cosmological constant $\Omega_\Lambda $, and the Hubble constant $H_0$, and
+find them to be consistent with the published results from the two data sets of
+Riess et al. 1998 (R98) and Perlmutter et al. 1999 (P99). We then examine the
+Hubble diagram (HD, i.e., the luminosity-redshift relation) in different
+directions on the sky by utilising spherical harmonic expansion. In particular,
+via the analysis of the dipole anisotropy, we divide the sky into the two
+hemispheres that yield the most discrepant of the three cosmological
+parameters, and the scatter $\chi^2_{\rm HD}$ in each case. The most discrepant
+values roughly move along the locus $-4\Omega_M +3 \Omega_{\Lambda} = 1$ (cf.
+P99), but by no more than $\Delta \approx 2.5$ along this line. For a perfect
+FRW universe, Monte Carlo realizations that mimic the current set of SNe yield
+values higher than the measured $\Delta$ in $\sim 1/5$ of the cases. We discuss
+implications for the validity of the Cosmological Principle, and possible
+calibration problems in the SNe data sets.",0008041v1
+2000-10-05,Planck LFI: Comparison Between Galaxy Straylight Contamination and other Systematic Effects,"The straylight contamination due to the Galactic emission (GSC, Galaxy
+Straylight Contamination) entering at large angles from the antenna centre
+direction may be one of the most critical sources of systematic effects in
+observations of the cosmic microwave background (CMB) anisotropies by future
+satellite missions like {\sc Planck} and MAP. We describe here different
+methods to evaluate the impact of this effect and compare it with other
+systematics of instrumental and astrophysical origin. The contributions within
+few degrees from the beam centre dominate the GSC near the Galaxy plane. The
+antenna sidelobes at intermediate and large angles from the beam centre
+dominate the GSC at medium and high Galactic latitudes. We find a GSC peak at
+$\sim 15\mu$K and a GSC angular power spectrum above that of the white noise
+for multipoles $\ell \lsim 10$ albeit smaller than that of CMB anisotropies by
+a factor larger than $\sim 10$. Although the GSC is largest at low Galactic
+latitudes, the contamination produced by far pattern features at medium and
+high Galactic latitudes, peaking at $\sim 4\mu$K, has to be carefully
+investigated, because the combination of low amplitude of Galaxy emission in
+those regions with the extremely good nominal {\sc Planck} sensitivity
+naturally makes high Galactic latitude areas the targets for unprecedentedly
+precise estimation of cosmological CMB anisotropy.",0010113v1
+2000-12-28,Probing the dark energy: methods and strategies,"The presence of dark energy in the Universe is inferred directly from the
+accelerated expansion of the Universe, and indirectly, from measurements of
+cosmic microwave background (CMB) anisotropy. Dark energy contributes about 2/3
+of the critical density, is very smoothly distributed, and has large negative
+pressure. Its nature is very much unknown. Most of its discernible consequences
+follow from its effect on evolution of the expansion rate of the Universe,
+which in turn affects the growth of density perturbations and the age of the
+Universe, and can be probed by the classical kinematic cosmological tests.
+Absent a compelling theoretical model (or even a class of models), we describe
+the dark energy by an effective equation-of-state w=p_X/\rho_X which is allowed
+to vary with time. We describe and compare different approaches for determining
+w(t), including magnitude-redshift (Hubble) diagram, number counts of galaxies
+and clusters, and CMB anisotropy, focusing particular attention on the use of a
+sample of several thousand type Ia supernova with redshifts z\lesssim 1.7, as
+might be gathered by the proposed SNAP satellite. Among other things, we derive
+optimal strategies for constraining cosmological parameters using type Ia
+supernovae. While in the near term CMB anisotropy will provide the first
+measurements of w, supernovae and number counts appear to have the most
+potential to probe dark energy.",0012510v1
+2001-01-22,Polarization of the Cosmic Microwave Background from Non-Uniform Reionization,"We study the signal in the Cosmic Microwave Background (CMB) polarization
+anisotropy resulting from patchy reionization. It is well known that the
+primordial polarization of the CMB is very sensitive to the details of
+reionization. Combining a semi-analytic model of galaxy formation, in which the
+optical depth to the reionization epoch is in the range 0.014 to 0.048, with a
+high resolution N-body simulation we find that reionization generates a peak
+with amplitude 0.05~0.15 \mu K at large angular scales. The position of this
+peak reveals the size of the horizon at reionization, whilst its amplitude is a
+measure of the optical depth to reionization. On small scales, ionized patches
+prior to full reionization create a second order polarization signal due to the
+coupling of the free electron density fluctuation with the quadrupole moment of
+the temperature anisotropy. Careful study reveals that the coupling generates
+the same power spectra for electric and magnetic modes, whose amplitudes of
+polarization anisotropies from this process are predicted to be ~10nK. The
+amplitude depends strongly on the total baryon density $\Omega_b$ and on the
+spatial correlations of the free electron density in the ionized regions, and
+weakly on the fraction of ionizing photons able to escape their source galaxy,
+$f_{esc}$. The first- and second-order signals are therefore sensitive to the
+details of how the reionization occurred. Detection of these signals will place
+important constraints on the reionization history of the Universe.",0101368v2
+2001-03-09,Rayleigh Scattering and Microwave Background Fluctuations,"During the recombination epoch, cosmic background photons couple not only to
+free electrons through Thompson scattering, but also to the neutral hydrogen
+through Rayleigh scattering. This latter is ~2% effect for photons near the
+peak of the photon energy distribution at z=800 and a ~0.2% effect at z=1100.
+Including Rayleigh scattering in the calculation reduces Silk damping at fixed
+redshift, alters the position of the surface of last scattering and alters the
+propagation of acoustic waves. We estimate the amplitude of these effects. For
+the Microwave Anisotropy Probe (MAP), Rayleigh scattering increases the
+anisotropy spectrum by 0.1% at the most. For the highest frequencies of the
+Planck Surveyor, the effects of Rayleigh scattering are much more dramatic
+(decreasing the anisotropy spectrum by 3% at \nu~550GHz and l~1000). The
+relative difference between the spectra of low and high frequencies is imposed
+by an oscillation with a function of multipole l and the oscillation amplitude
+is up to 0.5% between 100 and 550GHz. Rayleigh scattering also slows the
+decoupling between radiation and matter, but the effect is undetectably small.",0103149v3
+2001-03-12,Constraining the Properties of Dark Energy,"The presence of dark energy in the Universe is inferred directly from the
+accelerated expansion of the Universe, and indirectly, from measurements of
+cosmic microwave background (CMB) anisotropy. Dark energy contributes about 2/3
+of the critical density, is very smoothly distributed, and has large negative
+pressure. Its nature is very much unknown. Most of its discernible consequences
+follow from its effect on evolution of the expansion rate of the Universe,
+which in turn affects the growth of density perturbations and the age of the
+Universe, and can be probed by the classical kinematic cosmological tests.
+Absent a compelling theoretical model (or even a class of models), we describe
+dark energy by an effective equation of state w=p_X/rho_X which is allowed to
+vary with time. We describe and compare different approaches for determining
+w(t), including magnitude-redshift (Hubble) diagram, number counts of galaxies
+and clusters, and CMB anisotropy, focusing particular attention on the use of a
+sample of several thousand type Ia supernova with redshifts z < 1.7, as might
+be gathered by the proposed SNAP satellite. Among other things, we derive
+optimal strategies for constraining cosmological parameters using type Ia
+supernovae. While in the near term CMB anisotropy will provide the first
+measurements of w, supernovae and number counts appear to have the most
+potential to probe dark energy.",0103175v1
+2001-05-23,Squared temperature-temperature power spectrum as a probe of the CMB bispectrum,"It is now well known that mode-coupling effects associated with certain
+secondary effects generate higher order correlations in cosmic microwave
+background (CMB) temperature anisotropies, beyond the two-point function. In
+order to extract the non-Gaussian signal at the three-point level, we suggest a
+two-point statistic in the form of an angular power spectrum involving
+correlations between squared temperature and temperature anisotropies. This
+power spectrum contains compressed information from the bispectrum and can be
+easily measured in data with the same techniques that have been considered for
+the measurement of the usual temperature-temperature anisotropy power spectrum.
+We study the proposed power spectrum resulting from the non-Gaussian signal
+generated by correlations involved with gravitational lensing angular
+deflections in CMB and the Sunyave-Zel'dovich (SZ) effect due to large scale
+pressure fluctuations. Using the Planck frequency cleaned CMB and SZ maps, the
+CMB^2-SZ power spectrum provides a direct estimate of the cross-power between
+lensing angular deflections and the SZ effect. Through an optimal filter
+applied to the squared CMB map, the proposed statistic allows one to obtain all
+information from the lensing-SZ bispectrum. The observational measurement of
+the lensing-SZ cross-correlation is useful to understand the relation between
+large scale structure pressure and dark matter fluctuations.",0105415v1
+2001-09-25,Dark Matter in Dwarf Spheroidals I: Models,"This paper introduces a new two-parameter family of dwarf spheroidal (dSph)
+galaxy models. The density distribution has a Plummer profile and falls like
+the inverse fourth power of distance in projection, in agreement with the
+star-count data. The first free parameter controls the velocity anisotropy, the
+second controls the dark matter content. The dark matter distribution can be
+varied from one extreme of mass-follows-light through a near-isothermal halo
+with flat rotation curve to the other extreme of an extended dark halo with
+harmonic core. This family of models is explored analytically in some detail --
+the distribution functions, the intrinsic moments and the projected moments are
+all calculated. For the nearby Galactic dSphs, samples of hundreds of discrete
+radial velocities are becoming available. A technique is developed to extract
+the anisotropy and dark matter content from such data sets by maximising the
+likelihood function of the sample of radial velocities. This is constructed
+from the distribution function and corrected for observational errors and the
+effects of binaries. Tests on simulated data sets show that samples of 1000
+discrete radial velocities are ample to break the degeneracy between mass and
+anisotropy in the nearby dSphs. Interesting constraints can already be placed
+on the distribution of the dark matter with samples of 160 radial velocities
+(the size of the present-day data set for Draco).",0109451v2
+2002-04-03,Weak Lensing of the CMB: Extraction of Lensing Information from the Trispectrum,"We discuss the four-point correlation function, or the trispectrum in Fourier
+space, of CMB temperature and polarization anisotropies due to the weak
+gravitational lensing effect by intervening large scale structure. We discuss
+the squared temperature power spectrum as a probe of this trispectrum and, more
+importantly, as an observational approach to extracting the power spectrum of
+the deflection angle associated with the weak gravitational lensing effect on
+the CMB. We extend previous discussions on the trispectrum and associated weak
+lensing reconstruction from CMB data by calculating non-Gaussian noise
+contributions, beyond the previously discussed dominant Gaussian noise.
+Non-Gaussian noise contributions are generated by lensing itself and by the
+correlation between the lensing effect and other foreground secondary
+anisotropies in the CMB such as the Sunyaev-Zel'dovich (SZ) effect. When the SZ
+effect is removed from temperature maps using its spectral dependence, we find
+these additional non-Gaussian noise contributions to be an order of magnitude
+lower than the dominant Gaussian noise. If the noise-bias due to the dominant
+Gaussian part of the temperature squared power spectrum is removed, then these
+additional non-Gaussian contributions provide the limiting noise level for the
+lensing reconstruction. The temperature squared power spectrum allows a high
+signal-to-noise extraction of the lensing deflections and a confusion-free
+separation of the curl (or B-mode) polarization due to inflationary
+gravitational waves from that due to lensed gradient (or E-mode) polarization.
+The small angular scale temperature and polarization anisotropy measurements
+provide a novel approach to weak lensing studies, complementing the approach
+based on galaxy ellipticities.",0204068v1
+2002-04-04,Large Scale Structure in an Era of Precision CMB Measurements,"The advent of high signal-to-noise cosmic microwave background (CMB)
+anisotropy experiments now allow detailed studies on the statistics related to
+temperature fluctuations. The existence of acoustic oscillations in the
+anisotropy power spectrum is now established with the clear detection of the
+first, and to a lesser confidence the second and the third, peak. Beyond the
+acoustic peak structure associated with CMB photon temperature fluctuations, we
+study the possibility for an observational detection of oscillations in the
+large scale structure (LSS) matter power spectrum due to baryons. We also
+suggest a new cosmological test using the angular power spectrum of dark matter
+halos, or clusters of galaxies detected via wide-field surveys of the large
+scale structure. The standard rulers of the proposed test involve overall shape
+of the matter power spectrum and baryon oscillation peaks in projection. The
+test allows a measurement of the angular diameter distance as a function of
+redshift, similar to the distance to the last scattering surface from the first
+acoustic peak in the temperature anisotropy power spectrum. The simultaneous
+detection of oscillations in both photons and baryons will provide a strong,
+and a necessary, confirmation of our understanding related to the physics
+during the recombination era. The proposed studies can be carried out with a
+combined analysis of CMB data from missions such as the MAP and the large scale
+structure data from missions such as the DUET.",0204090v2
+2002-04-15,Small Angular Scale CMB Anisotropies from CBI and BIMA: Early Universe or Local structures ?,"The advent of high resolution cosmic microwave background (CMB) experiments
+now allows studies on the temperature fluctuations at scales corresponding to
+few arcminutes and below. Though the reported excess power at $\ell \sim 2000 -
+6000$ by CBI and BIMA is roughly consistent with a secondary contribution
+resulting from the Sunyaev-Zeldovich effect, this requires a higher
+normalization for the matter power spectrum than measured by other means. In
+addition to a local red-shift contribution, another strong possibility for
+anisotropies at very small scales involve non-standard aspects of inflationary
+models. To distinguish between contributions from early universe and local
+structures, including a potential point source contribution, and to understand
+the extent to which structures at low red-shifts contribute to small scale
+temperature anisotropies, it maybe necessary to perform a combined study
+involving CMB and the large scale structure. We suggest a cross-correlation of
+the temperature data with a map of the large scale structure, such as the
+galaxy distribution. For next generation small angular scale CMB experiments,
+multi-frequency observations may be a necessary aspect to allow an additional
+possibility to distinguish between these different scenarios.",0204250v3
+2003-01-06,"Compressible Magnetohydrodynamic Turbulence: mode coupling, scaling relations, anisotropy, new regime and astrophysical implications","We present numerical simulations and explore scalings and anisotropy of
+compressible magnetohydrodynamic (MHD) turbulence. Our study covers both gas
+pressure dominated (high beta) and magnetically dominated (low beta) plasmas at
+different Mach numbers. In addition, we present results for superAlfvenic
+turbulence and discuss in what way it is similar to the subAlfvenic turbulence.
+We describe a technique of separating different magnetohydrodynamic (MHD) modes
+(slow, fast and Alfven) and apply it to our simulations. We show that, for both
+high and low beta cases, Alfven and slow modes reveal the Kolmogorov spectrum
+(index=-5/3) and scale-dependent Goldreich-Sridhar anisotropy, while fast modes
+exhibit spectrum with index=-3/2 and isotropy. We discuss the statistics of
+density fluctuations arising from MHD turbulence at different regimes. Our
+findings entail numerous astrophysical implications ranging from cosmic ray
+propagation to gamma ray bursts and star formation. In particular, we show that
+the rapid decay of turbulence reported by earlier researchers is not related to
+compressibility and mode coupling in MHD turbulence. In addition, we show that
+magnetic field enhancements and density enhancements are marginally correlated.
+Addressing the density structure of partially ionized interstellar gas on AU
+scales, we show that the new regime of MHD turbulence that we earlier reported
+for incompressible flows persists for compressible turbulence and therefore may
+provide an explanation for those mysterious structures.",0301062v3
+2003-02-16,Anisotropies in the redshift-space correlations of galaxy groups and clusters II: Analysis of observational cluster samples,"We study the redshift space correlation function of galaxy clusters for
+observational samples constructed in different surveys. We explore correlation
+amplitudes, pairwise velocity distributions and bias factors. Systematics in
+cluster identification procedures are the main source of biased estimates of
+the correlation amplitude and inferred velocity dispersions. By comparing our
+results with those of numerical simulations we explore the strong influence on
+the clustering distortion pattern in redshift space from effects associated
+with the cluster identification procedure from two dimensional surveys as is
+the case of Abell and APM clusters. The identification of clusters in X-ray
+surveys improves this situation, although there are still systematic effects
+which are probably due to identification of optical sources in the
+determination of cluster redshifts. These systematics are particularly strong
+for the most luminous X-ray selected clusters in the Extended Bright Cluster
+Survey, which exhibits very large anisotropies, comparable to those present in
+the Abell catalogue. Our results demonstrate that forthcoming large redshift
+surveys will be extremely important for the construction of new samples of
+groups and clusters as well as improving the determination of optical and X-ray
+selected cluster distances, essential for reliable analyses of the large scale
+structure.",0302310v1
+2003-02-18,Current constraints on Cosmological Parameters from Microwave Background Anisotropies,"We compare the latest observations of Cosmic Microwave Background (CMB)
+Anisotropies with the theoretical predictions of the standard scenario of
+structure formation. Assuming a primordial power spectrum of adiabatic
+perturbations we found that the total energy density is constrained to be
+$\Omega_{tot}=1.03\pm0.06$ while the energy density in baryon and Cold Dark
+Matter (CDM) are $\Omega_bh^2=0.021\pm0.003$ and $\Omega_{cdm}h^2=0.12\pm0.02$,
+(all at 68% C.L.) respectively. The primordial spectrum is consistent with
+scale invariance, ($n_s=0.97\pm0.04$) and the age of the universe is
+$t_0=14.6\pm0.9$ Gyrs. Adding informations from Large Scale Structure and
+Supernovae, we found a strong evidence for a cosmological constant
+$\Omega_{\Lambda}=0.70_{-0.05}^{+0.07}$ and a value of the Hubble parameter
+$h=0.69\pm0.07$. Restricting this combined analysis to flat universes, we put
+constraints on possible 'extensions' of the standard scenario. A gravity waves
+contribution to the quadrupole anisotropy is limited to be $r \le 0.42$ (95%
+c.l.). A constant equation of state for the dark energy component is bound to
+be $w_Q \le -0.74$ (95% c.l.). We constrain the effective relativistic degrees
+of freedom $N_\nu \leq 6.2$ and the neutrino chemical potential $-0.01 \leq
+\xi_e \leq 0.18$ and $|\xi_{\mu,\tau}|\leq 2.3$ (massless neutrinos).",0302361v1
+2003-03-02,Small-scale CMB polarization anisotropies due to tangled primordial magnetic fields,"Tangled, primordial cosmic magnetic fields create small rotational velocity
+perturbations on the last scattering surface (LSS) of the cosmic microwave
+background radiation (CMBR). Such perturbations can contribute significantly to
+the CMBR temperature and polarization anisotropies at large l > 1000 or so,
+like the excess power detected by the CBI experiment. The magnetic contribution
+can be distinguished from most conventional signals, as they lead to CMBR
+polarization dominated by the odd parity, B-type signal. Experiments like DASI
+and WMAP have detected evidence for CMBR polarization at small l. Many
+experiments will also probe the large $l$ regime. We therefore calculate the
+polarization signals due to primordial magnetic fields, for different spectra
+and different cosmological parameters. A scale-invariant spectrum of tangled
+fields which redshifts to a present value B_{0}=3\times 10^{-9} Gauss, produces
+B-type polarization anisotropies of order 0.3 - 0.4 micro Kelvin between l of
+1000-5000. Larger signals result if the spectral index of magnetic tangles is
+steeper, n>-3. The peak of the signal shifts to larger l for a lambda-dominated
+universe, or if the baryon density is larger. The signal will also have
+non-Gaussian statistics. We also predict the much smaller E-type polarization,
+and T-E cross correlations for these models.",0303014v2
+2003-09-12,Stellar Orbits and the Interstellar Gas Temperature in Elliptical Galaxies,"We draw attention to the close relationship between the anisotropy parameter
+beta(r) for stellar orbits in elliptical galaxies and the temperature profile
+T(r) of the hot interstellar gas. For nearly spherical galaxies the gas density
+can be accurately determined from X-ray observations and the stellar luminosity
+density can be accurately found from the optical surface brightness. The Jeans
+equation and hydrostatic equilibrium establish a connection between beta(r) and
+T(r) that must be consistent with the observed stellar velocity dispersion.
+Purely optical observations of the bright elliptical galaxy NGC 4472 indicate
+beta(r) < 0.35 within the effective radius. However, the X-ray gas temperature
+profile T(r) for NGC 4472 requires significantly larger anisotropy, beta = 0.6
+- 0.7, about twice the optical value. This strong preference for radial stellar
+orbits must be understood in terms of the formation history of massive
+elliptical galaxies. Conversely, if the smaller, optically determined
+anisotropy is indeed correct, we are led to the important conclusion that the
+temperature profile T(r) of the hot interstellar gas in NGC 4472 must differ
+from that indicated by X-ray observations, or that the hot gas is not in
+hydrostatic equilibrium.",0309367v1
+2003-09-18,Sunyaev-Zel'dovich Effect by Multiple Sctattering : Numerical Solution of the Transfer Equations,"The radiative transfer equations for multiple inverse Compton scattering of
+the Cosmic Microwave Background Radiation (CMBR) by the hot intra-cluster
+electrons are solved numerically. The spherical isothermal and inhomogeneous
+$\beta$ model has been considered for the electron distribution. The anisotropy
+of the CMBR caused by scattering, known as thermal Sunyaev-Zel'dovich effect,
+along the radial axis of the medium is compared with the analytical solution of
+Kompaneets equation. The X-ray data of several clusters of galaxies at low
+redshifts provide an estimation of the central electron density $n_0$ to be of
+the order $10^{-3}$. It is found that for this value of $n_0$ the effect of
+multiple scattering is negligible. The numerically calculated anisotropy along
+the radial axis matches well with the analytical solution that describes single
+scattering. The result incorporating multiple scattering is fitted with the
+recent observation of Sunyaev-Zel'dovich effect in the cluster Abell 2163. It
+is shown that if $n_0$ is greater by an order of magnitude, which could be
+possible for cluster of galaxies at comparatively higher redshift, multiple
+scattering would play a significant role at the Wien region of the anisotropy
+spectrum. A fitting formula for the correction to the Sunyaev-Zel'dovich effect
+due to multiple scattering is provided.",0309507v1
+2003-09-29,Non-linear evolution of the cosmological background density field as diagnostic of the cosmological reionization,"We present constraints on the cosmological and reionization parameters based
+on the cumulative mass function of the Ly-alpha systems.
+  We find that the analysis of the cumulative mass function of the Ly-alpha
+systems indicates a reionization redshift z_r=24.2\+-4 (68%CL) in agreement
+with the value found on the basis of the WMAP anisotropy measurements, setting
+constraints on the amplitude of the density contrast, sigma_8=0.91+-0.04
+(68\CL), similar to those derived from the X-ray cluster temperature function.
+  Our joint analysis of Ly-alpha cumulative mass function and WMAP anisotropy
+measurements shows that the possible current identification of a running of the
+slope, dn_s/dlnk \ne 0, at k_p=0.05Mpc^-1 (multipole l of about 700) is mainly
+an effect of the existing degeneracy in the amplitude-slope plane at this
+scale, the result being consistent with the absence of running, the other
+constraints based on WMAP data remaining substantially unchanged.
+  Finally, we evaluate the progress on the determination the considered
+parameters achievable by using the final temperature anisotropy data from WMAP
+and from the forthcoming Planck satellite that will significantly improve the
+sensitivity and reliability of these results.
+  This work has been done in the framework of the Planck LFI activities.",0309785v1
+2003-11-21,Cross-Correlation Studies with CMB Polarization Maps,"The free-electron population during the reionized epoch rescatters CMB
+temperature quadrupole and generates a now well-known polarization signal at
+large angular scales. While this contribution has been detected in the
+temperature-polarization cross power spectrum measured with WMAP data, due to
+the large cosmic variance associated with anisotropy measurements at tens of
+degree angular scales only limited information related to reionization, such as
+the optical depth to electron scattering, can be extracted. The inhomogeneities
+in the free-electron population lead to an additional secondary polarization
+anisotropy contribution at arcminute scales. While the fluctuation amplitude,
+relative to dominant primordial fluctuations, is small, we suggest that a
+cross-correlation between arcminute scale CMB polarization data and a tracer
+field of the high redshift universe, such as through fluctuations captured by
+the 21 cm neutral Hydrogen background or those in the infrared background
+related to first proto-galaxies, may allow one to study additional details
+related to reionization. For this purpose, we discuss an optimized higher order
+correlation measurement, in the form of a three-point function, including
+information from large angular scale CMB temperature anisotropies in addition
+to arcminute scale polarization signal related to inhomogeneous reionization.
+We suggest that the proposed bispectrum can be measured with a substantial
+signal-to-noise ratio and does not require all-sky maps of CMB polarization or
+that of the tracer field. A measurement such as the one proposed may allow one
+to establish the epoch when CMB polarization related to reionization is
+generated and to address if the universe was reionized once or twice.",0311513v3
+2003-12-23,The CMB Power Spectrum from the Background Emission Anisotropy Scanning Telescope (BEAST) Experiment,"The Background Emission Anisotropy Scanning Telescope (BEAST) is a 2.2m
+off-axis telescope with an 8 element mixed Q (38-45GHz) and Ka (26-36GHz) band
+focal plane, designed for balloon borne and ground based studies of the Cosmic
+Microwave Background. Here we present the Cosmic Microwave Background (CMB)
+angular power spectrum calculated from 682 hours of data observed with the
+BEAST instrument. We use a binned pseudo-Cl estimator (the MASTER method). We
+find results that are consistent with other determinations of the CMB
+anisotropy for angular wavenumber l between 100 and 600. We also perform
+cosmological parameter estimation. The BEAST data alone produces a good
+constraint on Omega_k = 1-Omega_tot=-0.074 +/- 0.070, consistent with a flat
+Universe. A joint parameter estimation analysis with a number of previous CMB
+experiments produces results consistent with previous determinations.",0312610v1
+2004-02-15,Extended Mosaic Observations with the Cosmic Background Imager,"Two years of microwave background observations with the Cosmic Background
+Imager (CBI) have been combined to give a sensitive, high resolution angular
+power spectrum over the range 400 < l < 3500. This power spectrum has been
+referenced to a more accurate overall calibration derived from WMAP. The data
+cover 90 deg^2 including three pointings targeted for deep observations. The
+uncertainty on the l > 2000 power previously seen with the CBI is reduced.
+Under the assumption that any signal in excess of the primary anisotropy is due
+to a secondary Sunyaev-Zeldovich anisotropy in distant galaxy clusters we use
+CBI, ACBAR, and BIMA data to place a constraint on the present-day rms mass
+fluctuation sigma_8. We present the results of a cosmological parameter
+analysis on the l < 2000 primary anisotropy data which show significant
+improvements in the parameters as compared to WMAP alone, and we explore the
+role of the small-scale cosmic microwave background data in breaking parameter
+degeneracies.",0402359v2
+2004-05-25,Cross Terms and Weak Frequency Dependent Signals in the CMB Sky,"In this paper, we study the amplification of weak frequency dependent signals
+in the CMB sky due to their cross correlation to intrinsic anisotropies. In
+particular, we center our attention on mechanisms generating some weak signal,
+of peculiar spectral behaviour, such as resonant scattering in ionic, atomic or
+molecular lines, thermal SZ effect or extragalactic foreground emissions, whose
+typical amplitude (denoted by $\epsilon$) is sufficiently smaller than the
+intrinsic CMB fluctuations. We find that all these effects involve either the
+autocorrelation of anisotropies generated during recombination ($z_{rec}$) or
+the cross-correlation of those anisotropies with fluctuations arising at some
+later redshift $z_i$. The degree of this correlation can be computed under the
+assumption that density fluctuations were generated as standard inflationary
+models dictate and that they evolved in time according to linear theory. In
+case that the weak signal is frequency dependent, we show that, by substracting
+power spectra at different frequencies, it is possible to avoid the limit
+associated to Cosmic Variance and unveil weaker terms linear in $\epsilon$. We
+find that the correlation term shows a different spectral dependence than the
+squared ($\propto \epsilon^2$) term considered usually, making its extraction
+particularly straightforward for the thermal SZ effect. Furthermore, we find
+that in most cases the correlation terms are particularly relevant at low
+multipoles and must be taken into account when characterising the power
+spectrum associated to weak signals in the large angular scales.",0405487v2
+2004-06-03,CMB anisotropies from primordial inhomogeneous magnetic fields,"Primordial inhomogeneous magnetic fields of the right strength can leave a
+signature on the CMB temperature anisotropy and polarization. Potentially
+observable contributions to polarization B-modes are generated by vorticity and
+gravitational waves sourced by the magnetic anisotropic stress. We compute the
+corresponding CMB transfer functions in detail including the effect of
+neutrinos. The shear rapidly causes the neutrino anisotropic stress to cancel
+the stress from the magnetic field, suppressing the production of gravitational
+waves and vorticity on super-horizon scales after neutrino decoupling. A
+significant large scale signal from tensor modes can only be produced before
+neutrino decoupling, and the actual amplitude is somewhat uncertain. Plausible
+values suggest primordial nearly scale invariant fields of ~ 10^(-10)G today
+may be observable from their large scale tensor anisotropy. They can be
+distinguished from primordial gravitational waves by their non-Gaussianity.
+Vector mode vorticity sources B-mode power on much smaller scales with a power
+spectrum somewhat similar to that expected from weak lensing, suggesting
+amplitudes ~ 10^(-9)G may be observable on small scales for a spectral index of
+n ~ -2.9. In the appendix we review the covariant equations for computing the
+vector and tensor CMB power spectra that we implement numerically.",0406096v2
+2004-06-22,Dealing with systematics in cosmic shear studies: new results from the VIRMOS-Descart Survey,"We present a reanalysis of the VIRMOS-Descart weak lensing data, with a
+particular focus on different corrections for the variation of the point spread
+function anisotropy (PSF) across the CCDs. We show that the small scale
+systematics can be minimised, and eventually suppressed, using the B mode
+(curled shear component)measured in the corrected stars and galaxies. Updated
+cosmological constraints are obtained, free of systematics caused by PSF
+anisotropy. To facilitate general use of our results, we provide the two-points
+statistics data points with their covariance matrices up to a scale of one
+degree. For the normalisation of the mass power spectrum we obtain
+sigma_8=(0.83\pm 0.07)(Omega_M/0.3)^(-0.49). The shape parameter Gamma was
+marginalised over Gamma=[0.1,0.3] and the mean source redshift z_s over
+[0.8,1.0]. The latter is consistent with recent photometric redshifts obtained
+for the VIRMOS data and the preliminary spectroscopic redshifts from the
+VIRMOS-VVDS survey. The quoted 68% contour level includes all identified
+sources of error. We discuss the possible sources of residual contamination in
+this result: the effect of the non-linear mass power spectrum and remaining
+issues concerning the PSF correction. Our result is compared with the first
+release of the Wilkinson Microwave Anisotropy Probe data. It is found that Cold
+Dark Matter models with a power law primordial power spectrum and high matter
+density Omega_M > 0.5 are excluded at 3-sigma.",0406468v1
+2004-08-19,Gamma Ray Bursts: new rulers to measure the Universe,"The best measure of the Universe should be done using a standard ""ruler"" at
+any redshift. Type Ia Supernovae (SN Ia) probe the universe up to z$\sim$1.5,
+while the Cosmic Microwave Background (CMB) primary anisotropies concern
+basically $z\sim$1000. Apparently, Gamma--Ray Bursts (GRBs) are all but
+standard candles. However, their emission is collimated and the
+collimation--corrected energy correlates tightly with the frequency at which
+most of the radiation of the prompt is emitted, as found by Ghirlanda et al.
+(2004). Through this correlation we can infer the burst energy accurately
+enough to probe the intermediate redshift ($z<10$) Universe. Using the best
+known 15 GRBs we find very encouraging results that emphasize the cosmological
+GRB role. A combined fit with SN Ia yields $\Omega_{\rm M}=0.37\pm0.10$ and
+$\Omega_{\Lambda}=0.87\pm 0.23$. Assuming in addition a flat Universe, the
+parameters are constrained to be $\Omega_{\rm M}=0.29\pm0.04$ and
+$\Omega_{\Lambda}=0.71\pm 0.05$. GRBs accomplish the role of ""missing link""
+between SN Ia and CMB primary anisotropies. They can provide a new insight on
+the cosmic effects of dark energy, complementary to the one supplied by CMB
+secondary anisotropies through the Integrated Sachs Wolfe effect. The
+unexpected Standard Candle cosmological role of GRBs motivates the most
+optimistic hopes for what can be obtained when the GRB-dedicated satellite,
+Swift, will be launched.",0408350v1
+2005-02-02,Cosmological Constraints on the Very Low Frequency Gravitational-Wave Background,"While there are no strong observational constraints on the gravitational wave
+background across six or more orders of magnitude between 10^{-16} Hz and
+10^{-10} Hz and it is difficult to get a constraint below 10^{-12}Hz using
+objects in our Galaxy, we suggest that the anisotropy pattern of time variation
+of the redshift related to a sample of high redshift objects can be used to
+constrain the gravitational wave background around 10^{-12} Hz. Useful
+observations for the monitoring of an anisotropy signal in a global redshift
+change include spectroscopic observations of the Ly-alpha forest in absorption
+towards a sample of quasars, redshifted 21 cm line observations either in
+absorption or emission towards a sample of neutral HI regions before or during
+reionization, and high frequency (0.1 Hz to 1
+  Hz) gravitational wave analysis of a sample of neutron star--neutron star
+binaries detected with gravitational wave instruments such as the Decihertz
+Interferometer Gravitational Wave Observatory (DECIGO). The low frequency
+background can also be constrained by arcsecond-scale anisotropy observations
+of the CMB. For reasonable observations in the future involving extragalactic
+sources, we find best limits at the level of \Omega_{GW} < 10^{-5} at a
+frequency around 10^{-12} Hz while the eventual ultimate limit one cannot beat
+is \Omega_{GW} < 10^{-11}.",0502054v1
+2005-02-21,The effect of long range gravitational perturbations on the first acoustic peak of the cosmic microwave background,"In the standard cosmological model, the temperature anisotropy of the cosmic
+microwave background is interpreted as variation in the gravitational potential
+at the point of emission, due to the emitter being embedded in a region ${\cal
+C}$ of over- or under-density spanning the length (or size) scale $\lambda$ on
+which the anisotropy is measured. If the Universe is inhomogeneous, however,
+similar density contrasts of size $\lambda$ are also located everywhere
+surrounding ${\cal C}$. Since they are superposition states of many independent
+Fourier modes with no preferred direction, such primordial clumps and voids
+should not be configured according to some prescribed spatial pattern. Rather,
+they can randomly trade spaces with each other while preserving the
+Harrison-Zeldovich character of the matter spectrum. The outcome is an {\it
+extra} perturbation of the potential when averaged over length $\lambda$ at the
+emitter, and consequently an additional anisotropy on the same scale, which has
+apparently been overlooked. Unlike the conventional application of the
+Sachs-Wolfe effect to the WMAP observations, this extra effect is {\it not}
+scale independent over the $P(k) \sim k$ part of the matter spectrum, but
+increases towards smaller lengths, as $\sqrt{k}$. The consequence is a
+substantial revision of the currently advertised values of the key cosmological
+parameters, {\it unless} one postulates a more rapid decrease in the
+gravitational force with distance than that given by the inverse-square law.",0502430v2
+2005-03-08,The influence of non-uniform reionization on the CMB,"We investigate the impact of spatial variations in the ionized fraction
+during reionization on temperature anisotropies in the CMB. We combine
+simulations of large scale structure to describe the underlying density field
+with an analytic model based on extended Press-Schechter theory to track the
+reionization process. We find that the power spectrum of the induced CMB
+anisotropies depends sensitively on the character of the reionization epoch.
+Models that differ in the extent of the ""patchy phase"" could be distinguished
+by future experiments such as the Atacama Cosmology Telescope (ACT) and the
+South Pole Telescope (SPT). In our models, the patchy signal peaks at $l\simeq
+2000$, where it can be four times larger than the kinetic Sunyaev-Zel'dovich
+(kSZ)/Ostriker-Vishniac (OV) signal ($\Delta T_{\rm tot} \simeq 2.6 \mu K$). On
+scales beyond $l \simeq 4000$ the total Doppler signal is dominated by kSZ/OV,
+but the patchy signal can contribute up to 30% to the power spectrum. The
+effect of patchy reionization is largest on scales where the primordial CMB
+anisotropies dominate. Ignoring this contribution could lead to significant
+biases in the determination of cosmological parameters derived from CMB
+temperature measurements. Improvements in the theoretical modeling of the
+reionization epoch will become increasingly important to interpret the results
+of upcoming experiments.",0503166v2
+2005-05-14,Homeoidally striated density profiles: sequences of virial equilibrium configurations with constant anisotropy parameters,"The formulation of the tensor virial equations is generalized to unrelaxed
+configurations, where virial equilibrium does not coincide with dynamical (or
+hydrostatic) equilibrium. Further investigation is devoted to special classes
+of homeoidally striated ellipsoids, defined as homeoidally striated, Jacobi
+ellipsoids. In particular, virial equilibrium configurations with constant
+anisotropy parameters are studied with more detail, including both flattened
+and elongated, triaxial configurations, and the determination of the related
+bifurcation points. The explicit expression of different rotation parameters is
+also determined. An application is made to dark matter haloes hosting giant,
+galaxies, with regard to assigned initial and final configuration, following
+and generalizing to many respects a procedure conceived by Thuan & Gott (1975).
+The dependence of the limiting axis ratios, below which no configuration is
+allowed for the sequence under consideration, on the change in mass, total
+energy, and angular momentum, during the evolution, is illustrated in some
+representative situations. The dependence of axis ratios and rotation
+parameters on an additional parameter, related to the initial conditions of the
+density perturbation, is analysed in connection with a few special cases.
+Within the range of Peebles (1969) rotation parameter, inferred from
+high-resolution numerical simulations, the shape of dark matter haloes is
+mainly decided by the amount of anisotropy in residual velocity distribution.
+On the other hand, the contribution of rotation has only a minor effect on the
+meridional plane, and no effect on the equatorial plane, as bifurcation points
+occur for larger values of Peebles (1969) rotation parameter. To this respect,
+dark matter haloes are found to resemble giant elliptical galaxies.",0505306v1
+2005-07-11,Topological signatures in CMB temperature anisotropy maps,"We propose an alternative formalism to simulate CMB temperature maps in
+$\Lambda$CDM universes with nontrivial spatial topologies. This formalism
+avoids the need to explicitly compute the eigenmodes of the Laplacian operator
+in the spatial sections. Instead, the covariance matrix of the coefficients of
+the spherical harmonic decomposition of the temperature anisotropies is
+expressed in terms of the elements of the covering group of the space. We
+obtain a decomposition of the correlation matrix that isolates the topological
+contribution to the CMB temperature anisotropies out of the simply connected
+contribution. A further decomposition of the topological signature of the
+correlation matrix for an arbitrary topology allows us to compute it in terms
+of correlation matrices corresponding to simpler topologies, for which closed
+quadrature formulae might be derived. We also use this decomposition to show
+that CMB temperature maps of (not too large) multiply connected universes must
+show ``patterns of alignment'', and propose a method to look for these
+patterns, thus opening the door to the development of new methods for detecting
+the topology of our Universe even when the injectivity radius of space is
+slightly larger than the radius of the last scattering surface. We illustrate
+all these features with the simplest examples, those of flat homogeneous
+manifolds, i.e., tori, with special attention given to the cylinder, i.e.,
+$T^1$ topology.",0507238v2
+2005-09-05,Joint constraints on the lepton asymmetry of the Universe and neutrino mass from the Wilkinson Microwave Anisotropy Probe,"We use the Wilkinson Microwave Anisotropy Probe (WMAP) data on the spectrum
+of cosmic microwave background anisotropies to put constraints on the present
+amount of lepton asymmetry L, parameterized by the dimensionless chemical
+potential (also called degeneracy parameter) xi and on the effective number of
+relativistic particle species. We assume a flat cosmological model with three
+thermally distributed neutrino species having all the same mass and chemical
+potential, plus an additional amount of effectively massless exotic particle
+species. The extra energy density associated to these species is parameterized
+through an effective number of additional species DeltaN_oth$. We find that
+0<|xi|<1.1 and correspondingly 0<|L|<0.9 at 2sigma, so that WMAP data alone
+cannot firmly rule out scenarios with a large lepton number; moreover, a small
+preference for this kind of scenarios is actually found. We also discuss the
+effect of the asymmetry on the estimation of other parameters and in particular
+of the neutrino mass. In the case of perfect lepton symmetry, we obtain the
+standard results. When the amount of asymmetry is left free, we find \sum m_nu
+< 3.6 eV at 2sigma. Finally we study how the determination of |L| is affected
+by the assumptions on DeltaN_oth. We find that lower values of the extra energy
+density allow for larger values of the lepton asymmetry, effectively ruling
+out, at 2sigma level, lepton symmetric models with DeltaN_oth=0.",0509079v2
+2005-10-09,PSF Anisotropy and Systematic Errors in Weak Lensing Surveys,"Given the basic parameters of a cosmic shear weak lensing survey, how well
+can systematic errors due to anisotropy in the point spread function (PSF) be
+corrected? The largest source of error in this correction to date has been the
+interpolation of the PSF to the locations of the galaxies. To address this
+error, we separate the PSF patterns into components that recur in multiple
+exposures/pointings and those that vary randomly between different exposures
+(such as those due to the atmosphere). In an earlier study we developed a
+principal component approach to correct the recurring PSF patterns (Jarvis and
+Jain 2004). In this paper we show how randomly varying PSF patterns can also be
+circumvented in the measurement of shear correlations. For the two-point
+correlation function this is done by simply using pairs of galaxy shapes
+measured in different exposures. Combining the two techniques allows us to
+tackle generic combinations of PSF anisotropy patterns. The second goal of this
+paper is to give a formalism for quantifying residual systematic errors due to
+PSF patterns. We show how the main PSF corrections improve with increasing
+survey area (and thus can stay below the reduced statistical errors), and we
+identify the residual errors which do not scale with survey area. Our formalism
+can be applied both to planned lensing surveys to optimize instrumental and
+survey parameters and to actual lensing data to quantify residual errors.",0510231v2
+2005-11-24,A Cusp Slope -- Central Anisotropy Theorem,"For a wide class of self-gravitating systems, we show that if the density is
+cusped like 1/r^{gamma} near the center, then the limiting value of the
+anisotropy parameter beta = 1 - <v_T^2>/(2<v_r^2>) at the center may not be
+greater than (gamma/2). Here, <v_r^2> and <v_T^2> are the radial and tangential
+velocity second moments. This follows from the non-negativity of the phase
+space density. We compare this theorem to other proposed relations between the
+cusp slope and the central anisotropy to clarify their applicabilities and
+underlying assumptions. The extension of this theorem to tracer populations in
+an externally imposed potential is also derived. In particular, for stars
+moving in the vicinity of a central black hole, this reduces to gamma >=
+beta+(1/2), indicating that an isotropic system in Keplerian potential should
+be cusped at least as steep as 1/r^{0.5}. Similar limits have been noticed
+before for specific forms of the distribution function, but here we establish
+this as a general result.",0511686v4
+2006-02-15,High-Energy Activity in the Unusually Soft TeV Source HESS J1804-216 toward the Galactic Center,"In recent years, apparent anisotropies in the ~EeV cosmic ray (CR) flux
+arriving at Earth from the general direction of the galactic center have been
+reported from the analysis of AGASA and SUGAR data. The more recently
+commissioned Auger Observatory has not confirmed these results. HESS has now
+detected an unusually soft TeV source roughly coincident with the location of
+the previously claimed CR anisotropy. In this paper, we develop a model for the
+TeV emission from this object, consistent with observations at other
+wavelengths, and examine the circumstances under which it might have
+contributed to the $\sim$ EeV cosmic ray spectrum. We find that the supernova
+remnant G8.7-0.1 can plausibly account for all the known radiative
+characteristics of HESS J1804-216, but that it can accelerate cosmic rays only
+up to an energy $\sim 10^5$ GeV. On the other hand, the pulsar (PSR J1803-2137)
+embedded within this remnant can in principle inject EeV protons into the
+surrounding medium, but it cannot account for the broadband spectrum of HESS
+J1804-216. We therefore conclude that although G8.7-0.1 is probably the source
+of TeV photons originating from this direction, there is no compelling
+theoretical motivation for expecting a cosmic ray anisotropy at this location.
+However, if G8.7-0.1 is indeed correctly identified with HESS J1804-216, it
+should also produce a $\sim$ GeV flux detectable in a one-year all sky survey
+by GLAST.",0602330v1
+2006-03-16,The impacts of dark matter particle annihilation on recombination and the anisotropies of the cosmic microwave background,"The recombination history of the Universe provides a useful tool for
+constraining the annihilation of dark matter particles. Even a small fraction
+of dark matter particles annihilated during the cosmic dark age can provide
+sufficient energy to affect the ionization state of the baryonic gas. Although
+this effect is too small for neutralinos, lighter dark matter particle
+candidates, e.g. with mass of 1-100 MeV, which was proposed recently to explain
+the observed excess of positrons in the Galactic Center, may generate
+observable differences in the cosmic microwave background (CMB) temperature and
+polarization anisotropies. The annihilations at the era of recombination
+affects mainly the CMB anisotropy at small angular scales (large $\ell$), and
+is distinctively different from the effect of early reionization. We perform a
+multi-parameter analysis of the CMB data, including the both the WMAP first
+year and three year data, and the ACBAR, Boomerang, CBI, and VSA data. Assuming
+that the observed excess of $e^+e^-$ pairs in the galactic center region is
+produced by dark matter annihilation, and that a sizable fraction of the energy
+produced in the annihilation is deposited in the baryonic gas during
+recombination, we obtain a %95 dark matter mass limit of $M<8 \MeV$ with the
+current data set.",0603425v3
+2006-03-22,Small Scale Anisotropy Predictions for the Auger Observatory,"We study the small scale anisotropy signal expected at the Pierre Auger
+Observatory in the next 1, 5, 10, and 15 years of operation, from sources of
+ultra-high energy (UHE) protons. We numerically propagate UHE protons over
+cosmological distances using an injection spectrum and normalization that fits
+current data up to $\sim 10^{20}\eV$. We characterize possible sources of
+ultra-high energy cosmic rays (UHECRs) by their mean density in the local
+Universe, $\bar{\rho} = 10^{-r}$ Mpc$^{-3}$, with $r$ between 3 and 6.
+  These densities span a wide range of extragalactic sites for UHECR sources,
+from common to rare galaxies or even clusters of galaxies. We simulate 100
+realizations for each model and calculate the two point correlation function
+for events with energies above $4 \times 10^{19}\eV$ and above $10^{20}\eV$, as
+specialized to the case of the Auger telescope. We find that for $r\ga 4$,
+Auger should be able to detect small scale anisotropies in the near future.
+Distinguishing between different source densities based on cosmic ray data
+alone will be more challenging than detecting a departure from isotropy and is
+likely to require larger statistics of events. Combining the angular
+distribution studies with the spectral shape around the GZK feature will also
+help distinguish between different source scenarios.",0603615v1
+2006-04-04,"Robust Dark Energy Constraints from Supernovae, Galaxy Clustering, and Three-Year Wilkinson Microwave Anisotropy Probe Observations","Type Ia supernova (SN Ia), galaxy clustering, and cosmic microwave background
+anisotropy (CMB) data provide complementary constraints on the nature of the
+dark energy in the universe. We find that the three-year Wilkinson Microwave
+Anisotropy Probe (WMAP) observations give a CMB shift parameter of R =
+(\Omega_m H_0^2)^{1/2} \int_0^{z_{CMB}} dz'/H(z')= 1.70 \pm 0.03. Using this
+new measured value of the CMB shift parameter, together with the baryon
+acoustic oscillation (BAO) measurement from the Sloan Digital Sky Survey
+(SDSS), and SN Ia data from the HST/GOODS program and the first year Supernova
+Legacy Survey, we derive model-independent constraints on the dark energy
+density rho_X(z) and the cosmic expansion rate H(z). We also derive constraints
+on the dark energy equation of state w_X(z)=w_0+w'z (with cutoff at z=2) and
+w_X(a)=w_0+(1-a)w_a.
+  We find that current data provide slightly tighter constraints on rho_X(z)
+and H(z) as free functions in redshift, and roughly a factor of two improvement
+in constraining w_X(z). A cosmological constant remains consistent with data,
+however, uncertainties remain large for model-independent constraints of dark
+energy. Significant increase in the number of observed SNe Ia between redshifts
+of 1 and 2, complemented by improved BAO and weak lensing cosmography
+measurements (as expected from the JEDI mission concept for the Joint Dark
+Energy Mission), will be required to dramatically tighten model-independent
+dark energy constraints.",0604051v2
+2006-12-12,Radial stability of a family of anisotropic Hernquist models with and without a supermassive black hole,"We present a method to investigate the radial stability of a spherical
+anisotropic system that hosts a central supermassive black hole (SBH). Such
+systems have never been tested before for stability, although high anisotropies
+have been considered in the dynamical models that were used to estimate the
+masses of the central putative supermassive black holes. A family of analytical
+anisotropic spherical Hernquist models with and without a black hole were
+investigated by means of N-body simulations. A clear trend emerges that the
+supermassive black hole has a significant effect on the overall stability of
+the system, i.e. an SBH with a mass of a few percent of the total mass of the
+galaxy can prevent or reduce the bar instabilities in anisotropic systems. Its
+mass not only determines the strength of the instability reduction, but also
+the time in which this occurs. These effects are most significant for models
+with strong radial anisotropies. Furthermore, our analysis shows that unstable
+systems with similar SBH but with different anisotropy radii evolve
+differently: highly radial systems become oblate, while more isotropic models
+tend to form into prolate structures. In addition to this study, we also
+present a Monte-Carlo algorithm to generate particles in spherical anisotropic
+systems.",0612307v1
+2007-03-19,Cosmic Microwave Background Anisotropies up to Second Order,"These lecture notes present the computation of the full system of Boltzmann
+equations describing the evolution of the photon, baryon and cold dark matter
+fluids up to second order in perturbation theory, as recently studied in
+(Bartolo, Matarrese & Riotto 2006, 2007). These equations allow to follow the
+time evolution of the cosmic microwave background anisotropies at all angular
+scales from the early epoch, when the cosmological perturbations were
+generated, to the present, through the recombination era. The inclusion of
+second-order contributions is mandatory when one is interested in studying
+possible deviations from Gaussianity of cosmological perturbations, either of
+primordial (e.g. inflationary) origin or due to their subsequent evolution.
+Most of the emphasis in these lectures notes will be given to the derivation of
+the relevant equations for the study of cosmic microwave background
+anisotropies and to their analytical solutions.",0703496v2
+1999-07-13,Anomalous scaling of a passive scalar advected by the synthetic compressible flow,"The field theoretic renormalization group and operator product expansion are
+applied to the problem of a passive scalar advected by the Gaussian
+nonsolenoidal velocity field with finite correlation time, in the presence of
+large-scale anisotropy. The energy spectrum of the velocity in the inertial
+range has the form $E(k)\propto k^{1-\epsilon}$, and the correlation time at
+the wavenumber $k$ scales as $k^{-2+\eta}$. It is shown that, depending on the
+values of the exponents $\epsilon$ and $\eta$, the model exhibits various types
+of inertial-range scaling regimes with nontrivial anomalous exponents. Explicit
+asymptotic expressions for the structure functions and other correlation
+functions are obtained; they are represented by superpositions of power laws
+with nonuniversal amplitudes and universal (independent of the anisotropy)
+anomalous exponents, calculated to the first order in $\epsilon$ and $\eta$ in
+any space dimension. These anomalous exponents are determined by the critical
+dimensions of tensor composite operators built of the scalar gradients, and
+exhibit a kind of hierarchy related to the degree of anisotropy: the less is
+the rank, the less is the dimension and, consequently, the more important is
+the contribution to the inertial-range behavior. The leading terms of the even
+(odd) structure functions are given by the scalar (vector) operators. The
+anomalous exponents depend explicitly on the degree of compressibility.",9907018v1
+1996-01-31,Instabilities in the Flux Line Lattice of Anisotropic Superconductors,"The stability of the flux line lattice has been investigated within
+anisotropic London theory. This is the first full-scale investigation of
+instabilities in the `chain' state. It has been found that the lattice is
+stable at large fields, but that instabilities occur as the field is reduced.
+The field at which these instabilities first arise, $b^*(\epsilon,\theta)$,
+depends on the anisotropy $\epsilon$ and the angle $\theta$ at which the
+lattice is tilted away from the $c$-axis. These instabilities initially occur
+at wavevector $k^*(\epsilon,\theta)$, and the component of $k^*$ along the
+average direction of the flux lines, $k_z$, is always finite. As the
+instability occurs at finite $k_z$ the dependence of the cutoff on $k_z$ is
+important, and we have used a cutoff suggested by Sudb\ospace and Brandt. The
+instabilities only occur for values of the anisotropy $\epsilon$ appropriate to
+a material like BSCCO, and not for anisotropies more appropriate to YBCO. The
+lower critical field $H_{c_1}(\phi)$ is calculated as a function of the angle
+$\phi$ at which the applied field is tilted away from the crystal axis. The
+presence of kinks in $H_{c_1}(\phi)$ is seen to be related to instabilities in
+the equilibrium flux line structure.",9601154v2
+1998-01-06,Quasi-Long-Range Order in Random-Anisotropy Heisenberg Models,"Monte Carlo simulations have been used to study a discretized Heisenberg
+ferromagnet (FM) with random uniaxial single-site anisotropy on $L \times L
+\times L$ simple cubic lattices, for $L$ up to 64. The spin variable on each
+site is chosen from the twelve [110] directions. The random anisotropy has
+infinite strength and a random direction on a fraction $x$ of the sites of the
+lattice, and is zero on the remaining sites. In many respects the behavior of
+this model is qualitatively similar to that of the corresponding random-field
+model. Due to the discretization, for small $x$ at low temperature there is a
+[110] FM phase. For $x>0$ there is an intermediate quasi-long-range ordered
+(QLRO) phase between the paramagnet and the ferromagnet, which is characterized
+by a $|k|^{-3}$ divergence of the magnetic structure factor S$(k)$ for small
+$k$, but no true FM order. At the transition between the paramagnetic and QLRO
+phases S$(k)$ diverges like $|k|^{-2}$. The limit of stability of the QLRO
+phase is somewhat greater than $x=0.5$. For $x$ close to 1 the low temperature
+form of S$(k)$ can be fit by a Lorentzian, with a correlation length estimated
+to be $11 \pm 1$ at $x=1.0$ and $25 \pm 5$ at $x=0.75$.",9801033v1
+1998-04-06,Scaling of a slope: the erosion of tilted landscapes,"We formulate a stochastic equation to model the erosion of a surface with
+fixed inclination. Because the inclination imposes a preferred direction for
+material transport, the problem is intrinsically anisotropic. At zeroth order,
+the anisotropy manifests itself in a linear equation that predicts that the
+prefactor of the surface height-height correlations depends on direction. The
+first higher-order nonlinear contribution from the anisotropy is studied by
+applying the dynamic renormalization group. Assuming an inhomogeneous
+distribution of soil substrate that is modeled by a source of static noise, we
+estimate the scaling exponents at first order in $\ep$-expansion. These
+exponents also depend on direction. We compare these predictions with empirical
+measurements made from real landscapes and find good agreement. We propose that
+our anisotropic theory applies principally to small scales and that a
+previously proposed isotropic theory applies principally to larger scales.
+Lastly, by considering our model as a transport equation for a driven diffusive
+system, we construct scaling arguments for the size distribution of erosion
+``events'' or ``avalanches.'' We derive a relationship between the exponents
+characterizing the surface anisotropy and the avalanche size distribution, and
+indicate how this result may be used to interpret previous findings of
+power-law size distributions in real submarine avalanches.",9804067v2
+1998-07-28,Thermal Conductivity of the Accidental Degeneracy and Enlarged Symmetry Group Models for Superconducting UPt<sub>3</sub>,"We present theoretical calculations of the thermal conductivity for the
+accidental degeneracy and enlarged symmetry group models that have been
+proposed to explain the phase diagram of UPt3. The order parameters for these
+models possess point nodes or cross nodes, reflecting the broken symmetries of
+the ground state. These broken symmetries lead to robust predictions for the
+ratio of the low-temperature thermal conductivity for heat flow along the c
+axis and in the basal plane. The anisotropy of the heat current response at low
+temperatures is determined by the phase space for scattering by impurities. The
+measured anisotropy ratio, $\kappa_c/\kappa_b$, provides a strong constraint of
+theoretical models for the ground state order parameter. The accidental
+degeneracy and enlarged symmetry group models based on no spin-orbit coupling
+do not account for the thermal conductivity of UPt3. The models for the order
+parameter that fit the experimental data for the c and b directions of the heat
+current are the 2D E1g and E2u models, for which the order parameters possess
+line nodes in the ab-plane and point nodes along the c axis, and the A1g+E1g
+model of Zhitomirsky and Ueda. This model spontaneously breaks rotational
+symmetry in theab-plane below Tc2 and predicts a large anisotropy for the
+$ab$-plane heat current.",9807370v1
+1998-12-31,Effect of disorder on quantum phase transitions in anisotropic XY spin chains in a transverse field,"We present some exact results for the effect of disorder on the critical
+properties of an anisotropic XY spin chain in a transverse field. The continuum
+limit of the corresponding fermion model is taken and in various cases results
+in a Dirac equation with a random mass. Exact analytic techniques can then be
+used to evaluate the density of states and the localization length. In the
+presence of disorder the ferromagnetic-paramagnetic or Ising transition of the
+model is in the same universality class as the random transverse field Ising
+model solved by Fisher using a real space renormalization group decimation
+technique (RSRGDT). If there is only randomness in the anisotropy of the
+magnetic exchange then the anisotropy transition (from a ferromagnet in the $x$
+direction to a ferromagnet in the $y$ direction) is also in this universality
+class. However, if there is randomness in the isotropic part of the exchange or
+in the transverse field then in a non-zero transverse field the anisotropy
+transition is destroyed by the disorder. We show that in the Griffiths' phase
+near the Ising transition that the ground state energy has an essential
+singularity. The results obtained for the dynamical critical exponent, the
+typical correlation length, and the temperature dependence of the specific heat
+near the Ising transition agree with the results of the RSRGDT and numerical
+work.",9812430v1
+1999-10-14,Effect of symmetry breaking perturbations in the one-dimensional SU(4) spin-orbital model,"We study the effect of symmetry breaking perturbations in the one-dimensional
+SU(4) spin-orbital model. We allow the exchange in spin ($J_1$) and orbital
+($J_2$) channel to be different and thus reduce the symmetry to SU(2) $\otimes$
+SU(2). A magnetic field $h$ along the $S^z$ direction is also applied. Using
+the formalism developped by Azaria et al we extend their analysis of the
+isotropic $J_1=J_2$, h=0 case and obtain the low-energy effective theory near
+the SU(4) point in the asymmetric case. An accurate analysis of the
+renormalization group flow is presented with a particular emphasis on the
+effect of the anisotropy. In zero magnetic field, we retrieve the same
+qualitative low-energy physics than in the isotropic case. In particular, the
+massless behavior found on the line $J_1=J_2>K/4$ extends in a large
+anisotropic region. We discover though that the anisotropy plays its trick in
+allowing non trivial scaling behaviors of the physical quantities. When a
+magnetic field is present the effect of the anisotropy is striking. In addition
+to the usual commensurate-incommensurate phase transition that occurs in the
+spin sector of the theory, we find that the field may induce a second
+transition of the KT type in the remaining degrees of freedom to which it does
+not couple directly. In this sector, we find that the effective theory is that
+of an SO(4) Gross-Neveu model with an h-dependent coupling that may change its
+sign as h varies.",9910218v2
+1999-12-28,Effects of microscopic strain distribution on Ga(1-x)In(x)As quantum wires grown by strain-induced lateral ordering,"Band Structures and optical matrix elements of quantum wires(QWR's) made of
+short-period superlattices(SPS) with strain-induced lateral ordering(SILO) are
+investigated theoretically via an effective bond-orbital model(EBOM) combined
+with a valence-force field(VFF) model. Valence-band anistropy, band mixing, and
+effects due to local strain distribution at the atomistic level are all taken
+into account. In particular, Ga(1-x)In(x)As QWR's grown by SILO process are
+considered. A VFF model is used to find the equilibrium atomic positions in the
+SILO QWR structure by minimizing the lattice energy. The strain tensor at each
+atomic(In or GA) site is then obtained and included in the calculations of
+electronic states and optical peroperties. It is found that different local
+arrangement of atoms leads to very different strain distribution, which in term
+alters the optical properties. In particular, we found that the optical
+anisotropy can be reversed due to the change in shear strain caused by the
+inter-change of atomic positions. Good agreement with the existing experimental
+data on band gap and optical anisotropy can be obtained when a 2D alloy
+structure with lateral composition modulation in the InAs/GaAs interface planes
+of the SPS is used. Our studies revealed the possibility of ""shear-strain
+engineering"" in SILO QWR light-emitting devices to achieve desired optical
+anisotropy.",9912468v3
+2000-04-21,First-principles study of ferroelectric and antiferrodistortive instabilities in tetragonal SrTiO3,"We carry out first-principles density-functional calculations of the
+antiferrodistortive (AFD) and ferroelectric (FE) soft-mode instabilities in
+tetragonal SrTiO3, with the structural degrees of freedom treated in a
+classical, zero-temperature framework. In particular, we use frozen-phonon
+calculations to make a careful study of the anisotropy of the AFD and FE mode
+frequencies in the tetragonal ground state, in which an R-point AFD soft phonon
+has condensed. Because of the anharmonic couplings, the presence of this AFD
+distortion substantially affects both the AFD and FE mode frequencies. The AFD
+mode is found to be softer for rotations around a perpendicular axis (Eg mode)
+than for rotations about the tetragonal axis (A1g mode), in agreement with
+experimental results. The FE mode, on the other hand, is found to be softer
+when polarized perpendicular to the tetragonal axis (Eu mode) than parallel to
+it (A2u mode). The sign of this frequency splitting is consistent with the
+experimentally reported anisotropy of the dielectric susceptibility and other
+evidence. Finally, we present a discussion of the influence of various types of
+structural distortions on the FE instability and its anisotropy.",0004372v1
+2000-05-23,Systematic study of Ga$_{1-x}$In$_x$As self-assembled quantum wires with different interfacial strain relaxation,"A systematic theoretical study of the electronic and optical properties of
+Ga$_{1-x}$In$_x$As self-assembled quantum-wires (QWR's) made of short-period
+superlattices (SPS) with strain-induced lateral ordering is presented. The
+theory is based on the effective bond-orbital model (EBOM) combined with a
+valence-force field (VFF) model. Valence-band anisotropy, band mixing, and
+effects due to local strain distribution at the atomistic level are all taken
+into account. Several structure models with varying degrees of alloy mixing for
+lateral modulation are considered. A valence force field model is used to find
+the equilibrium atomic positions in the QWR structure by minimizing the lattice
+energy. The strain tensor at each atomic (In or Ga) site is then obtained and
+included in the calculation of electronic states and optical properties. It is
+found that different local arrangement of atoms leads to very different strain
+distribution, which in turn alters the optical properties. In particular, we
+found that in model structures with thick capping layer the electron and hole
+are confined in the Ga-rich region and the optical anisotropy can be reversed
+due to the variation of lateral alloying mixing, while for model structures
+with thin capping layer the electron and hole are confined in the In-rich
+region, and the optical anisotropy is much less sensitive to the lateral alloy
+mixing.",0005392v1
+2001-09-04,"Fully relativistic calculation of magnetic properties of Fe, Co and Ni adclusters on Ag(100)","We present first principles calculations of the magnetic moments and magnetic
+anisotropy energies of small Fe, Co and Ni clusters on top of a Ag(100) surface
+as well as the exchange-coupling energy between two single adatoms of Fe or Co
+on Ag(100). The calculations are performed fully relativistically using the
+embedding technique within the Korringa-Kohn-Rostoker method. The magnetic
+anisotropy and the exchange-coupling energies are calculated by means of the
+force theorem. In the case of adatoms and dimers of iron and cobalt we obtain
+enhanced spin moments and, especially, unusually large orbital moments, while
+for nickel our calculations predict a complete absence of magnetism. For larger
+clusters, the magnitudes of the local moments of the atoms in the center of the
+cluster are very close to those calculated for the corresponding monolayers.
+Similar to the orbital moments, the contributions of the individual atoms to
+the magnetic anisotropy energy strongly depend on the position, hence, on the
+local environment of a particular atom within a given cluster. We find strong
+ferromagnetic coupling between two neighboring Fe or Co atoms and a rapid,
+oscillatory decay of the exchange-coupling energy with increasing distance
+between these two adatoms.",0109045v1
+2002-03-06,c-Axis Transport and Resistivity Anisotropy of Lightly- to Moderately-Doped La_{2-x}Sr_{x}CuO_{4} Single Crystals: Implications on the Charge Transport Mechanism,"Both the in-plane and the out-of-plane resistivities (\rho_{ab} and \rho_{c})
+are measured in high-quality La_{2-x}Sr_{x}CuO_{4} (LSCO) single crystals in
+the lightly- to moderately-doped region, x = 0.01 to 0.10, and the resistivity
+anisotropy is determined. In all the samples studied, the anisotropy ratio \rho
+_{c}/\rho_{ab} quickly increases with decreasing temperature, although in
+non-superconducting samples the strong localization effect causes \rho
+_{c}/\rho_{ab} to decrease at low temperatures. Most notably, it is found that
+\rho_{c}/\rho_{ab} at moderate temperatures (100 - 300 K) is almost completely
+independent of doping in the non-superconducting regime (x = 0.01 to 0.05);
+this indicates that the same charge confinement mechanism that renormalizes the
+c-axis hopping rate is at work down to x = 0.01. It is discussed that this
+striking x-independence of \rho_{c}/\rho_{ab} is consistent with the idea that
+holes form a self-organized network of hole-rich regions, which also explains
+the unusually metallic in-plane transport of the holes in the lightly-doped
+region. Furthermore, the data for x > 0.05 suggest that the emergence of the
+superconductivity is related to an increase in the c-axis coupling.",0203107v1
+2002-03-12,Angular dependence of magnetoresistivity in c-oriented MgB2 thin film,"The anisotropy of MgB2 is still under debate: its value, strongly dependent
+on the sample and on the measuring method, ranges between 1.2 and 13. In this
+work we present our results on a MgB2 c-oriented superconducting thin film. To
+evaluate the anisotropy, we followed two different approaches. Firstly,
+magnetoresistivity was measured as a function of temperature at selected
+magnetic fields applied both parallel and perpendicular to the c-axis;
+secondly, we measured magnetoresistivity at selected temperatures and magnetic
+fields, varying the angle q between the magnetic field and the c-axis. The
+anisotropy estimated from the ratio between the upper critical fields parallel
+and perpendicular to the c-axis and the one obtained in the framework of the
+scaling approach within the anisotropic Ginzburg-Landau theory are different
+but show a similar trend in the temperature dependence. The obtained results
+are compared and discussed in the light of the two-band nature of MgB2. A
+comparison between critical fields in thin films and single crystal is also
+performed.",0203246v3
+2002-05-15,Evolution of the resistivity anisotropy in Bi_{2}Sr_{2-x}La_{x}CuO_{6+δ} single crystals for a wide range of hole doping,"To elucidate how the temperature dependence of the resistivity anisotropy of
+the cuprate superconductors changes with hole doping, both the in-plane and the
+out-of-plane resistivities (\rho_{ab} and \rho_{c}) are measured in a series of
+high-quality Bi_{2}Sr_{2-x}La_{x}CuO_{6+\delta} (BSLCO) single crystals for a
+wide range of x (x = 0.23 - 1.02), which corresponds to the hole doping per Cu,
+p, of 0.03 - 0.18. The anisotropy ratio, \rho_{c}/\rho_{ab}, shows a systematic
+increase with decreasing p at moderate temperatures, except for the most
+underdoped composition where the localization effect enhances \rho_{ab} and
+thus lowers \rho_{c}/\rho_{ab}. The exact p dependence of \rho_{c}/\rho_{ab} at
+a fixed temperature is found to be quite peculiar, which is discussed to be due
+to the effect of the pseudogap that causes \rho_{c}/\rho_{ab} to be
+increasingly more enhanced as p is reduced. The pseudogap also causes a rapid
+growth of \rho_{c}/\rho_{ab} with decreasing temperature, and, as a result, the
+\rho_{c}/\rho_{ab} value almost reaches 10^6 in underdoped samples just above
+T_c. Furthermore, it is found that the temperature dependence of \rho_{c} of
+underdoped samples show two distinct temperature regions in the pseudogap
+phase, which suggests that the divergence of \rho_{c} below the pseudogap
+temperature is governed by two different mechanisms.",0205305v2
+2002-09-16,"Correlation energy, quantum phase transition, and bias potential effects in quantum Hall bilayers at nu=1","We study the correlation energy, the effective anisotropy parameter, and
+quantum fluctuations of the pseudospin magnetization in bilayer quantum Hall
+systems at total filling factor nu=1 by means of exact diagonalizations of the
+Hamiltonian in the spherical geometry. We compare exact diagonalization results
+for the ground state energy with finite-size Hartree-Fock values. In the
+ordered ground state phase at small layer separations the Hartree-Fock data
+compare reasonably with the exact results. Above the critical layer separation,
+however, the Hartree-Fock findings still predict an increase in the ground
+state energy, while the exact ground state energy is in this regime independent
+of the layer separation indicating the decoupling of layers and the loss of
+spontaneous phase coherence between them. We also find accurate values for the
+pseudospin anisotropy constant whose dependence of the layer separation
+provides another very clear indication for the strong interlayer correlations
+in the ordered phase and shows an inflection point at the phase boundary.
+Finally we discuss the possibility of interlayer correlations in biased systems
+even above the phase boundary for the balanced case. Certain features of our
+data for the pseudospin anisotropy constant as well as for quantum fluctuations
+of the pseudospin magnetization are not inconsistent with the occurence of this
+effect. However, it appears to be rather weak at least in the limit of
+vanishing tunneling amplitude.",0209349v2
+2003-07-02,Specific Heat Study of the Magnetic Superconductor HoNi2B2C,"The complex magnetic transitions and superconductivity of HoNi2B2C were
+studied via the dependence of the heat capacity on temperature and in-plane
+field angle. We provide an extended, comprehensive magnetic phase diagram for B
+// [100] and B // [110] based on the thermodynamic measurements. Three magnetic
+transitions and the superconducting transition were clearly observed. The 5.2 K
+transition (T_{N}) shows a hysteresis with temperature, indicating the first
+order nature of the transition at B=0 T. The 6 K transition (T_{M}), namely the
+onset of the long-range ordering, displays a dramatic in-plane anisotropy:
+T_{M} increases with increasing magnetic field for B // [100] while it
+decreases with increasing field for B // [110]. The anomalous anisotropy in
+T_{M} indicates that the transition is related to the a-axis spiral structure.
+The 5.5 K transition (T^{*}) shows similar behavior to the 5.2 K transition,
+i.e., a small in-plane anisotropy and scaling with Ising model. This last
+transition is ascribed to the change from a^{*} dominant phase to c^{*}
+dominant phase.",0307041v4
+2003-08-13,Effect of varying material anisotropy on critical current anistropy in vicinal YBa$_2$Cu$_3$O$_{7-δ}$ thin films,"The high $T_{c}$ cuprate superconductors are noted for their anisotropic
+layered structure, certain of these materials indeed tend toward the limit of a
+Lawrence-Doniach superconductor. However, YBa$_2$Cu$_3$O$_{7-\delta}$ has a
+smaller anisotropy than would be expected from its interlayer spacing. This is
+due to the cuprate chains in the structure. To investigate the influence of the
+chain oxygen on transport properties critical current versus applied field
+angle measurements were performed on fully oxygenated and de-oxygenated
+YBa$_2$Cu$_3$O$_{7-\delta}$ thin films and optimally oxygenated
+Y$_{0.75}$Ca$_{0.2}$Ba$_2$Cu$_3$O$_{7-\delta}$ thin films. The films were grown
+on 10$^{\circ}$ mis-cut SrTiO$_3$ substrates to enable the intrinsic vortex
+channelling effect to be observed. The form of the vortex channelling minimum
+observed in field angle dependent critical current studies on the films was
+seen to depend on film oxygenation. The vortex channelling effect is dependent
+on a angular dependent cross-over to a string-pancake flux line lattice. The
+results obtained appear to be consistent with the prediction of Blatter et al.
+[Rev. Mod. Phys., 66 (4): 1125 (1994)] that increased superconducting
+anisotropy leads to the kinked string-pancake lattice existing over a smaller
+angular range.",0308246v1
+2003-09-26,Magnetic phases and reorientation transitions in antiferromagnetically coupled multilayers,"In antiferromagnetically coupled superlattices grown on (001) faces of cubic
+substrates, e.g. based on materials combinations as Co/Cu, Fe/Si, Co/Cr, or
+Fe/Cr, the magnetic states evolve under competing influence of bilinear and
+biquadratic exchange interactions, surface-enhanced four-fold in-plane
+anisotropy, and specific finite-size effects. Using phenomenological
+(micromagnetic) theory, a comprehensive survey of the magnetic states and
+reorientation transitions has been carried out for multilayer systems with even
+number of ferromagnetic sub-layers and magnetizations in the plane. In
+two-layer systems (N=2) the phase diagrams in dependence on components of the
+applied field in the plane include ``swallow-tail'' type regions of
+(metastable) multistate co-existence and a number of continuous and
+discontinuous reorientation transitions induced by radial and transversal
+components of the applied field. In multilayers (N \ge 4) noncollinear states
+are spatially inhomogeneous with magnetization varying across the multilayer
+stack. For weak four-fold anisotropy the magnetic states under influence of an
+applied field evolve by a complex continuous reorientation into the saturated
+state. At higher anisotropy they transform into various inhomogeneous and
+asymmetric structures. The discontinuous transitions between the magnetic
+states in these two-layers and multilayers are characterized by broad ranges of
+multi-phase coexistence of the (metastable) states and give rise to specific
+transitional domain structures.",0309621v1
+2004-04-10,Effects of anisotropy on a quantum Heisenberg spin glass in a three-dimensional hierarchical lattice,"We study the anisotropic Heisenberg spin-glass model in a three-dimensional
+hierarchical lattice (designed to approximate the cubic lattice), within a
+real-space renormalization-group approach. Two different initial probability
+distributions for the exchange interaction ($J_{ij}$), Gaussian and uniform,
+are used, with zero mean and width $\bar{J}$. The $(kT/\bar{J}) \times
+\Delta_0$ phase diagram is obtained, where $T$ is the temperature, $\Delta_0$
+is the first moment of the probability distribution for the uniaxial
+anisotropy, and $k$ is the Boltzmann constant. For the Ising model
+($\Delta_0=1$), there is a spin-glass phase at low temperatures (high
+$\bar{J}$) and a paramagnetic phase at high temperatures (low $\bar{J}$). For
+the isotropic Heisenberg model ($\Delta_0=0$), our results indicate no
+spin-glass phase at finite temperatures. The transition temperature between the
+spin-glass and paramagnetic phase decreases with $\Delta_0$, as expected, but
+goes to zero at a finite value of the anisotropy parameter, namely $\Delta_0 =
+\Delta_c \sim 0.59$. Our results indicate that the whole transition line,
+between the paramagnetic and the spin-glass phases, for $\Delta_c \leq \Delta_0
+< 1$, belongs to the same universality class as the transition for the Ising
+spin glass.",0404251v2
+2004-06-08,Decoupled two-dimensional superconductivity and continuous melting transitions in layered superconductors immersed in a parallel magnetic field,"Possible phases and the B-T phase diagram of interlayer Josephson vortices
+induced by a magnetic field parallel to the superconducting layers are
+investigated by Monte Carlo simulations based on the anisotropic, frustrated XY
+model. While for low magnetic fields and small anisotropy parameters a single
+first-order transition is observed similarly to the melting of Abrikosov (or
+pancake) vortex lattice, an intermediate phase, characterized by decoupled,
+two-dimensional (2D) quasi long-range crystalline order (QLRCO) and
+superconductivity, is found at high magnetic fields and large anisotropy
+parameters. Combining the simulation results with a symmetry argument, it is
+revealed that this intermediate phase is of Kosterlitz-Thouless (KT) type, and
+the melting of 2D quasi Josephson vortex lattices and suppression of
+superconductivity is a KT transition. Evolution of the intermediate phase to
+the low-temperature phase of 3D LRCO is second order and belongs to the 3D XY
+universality class. The three phase boundaries merge at a multicritical point.
+It is revealed that decoupling of the 3D Josephson vortex lattice into the 2D
+phase is triggered by hops of Josephson flux lines across superconducting
+layers activated by thermal fluctuations. The equilibrium phase diagram with
+the KT phase at high magnetic fields and large anisotropy parameters is
+consistent with the peculiar Lorentz-force-independent dissipation observed in
+highly anisotropic high-Tc superconductor Bi2Sr2CaCu2O(8+y) by Iye et al.
+(Physica 159C, 433 (1989)).",0406183v1
+2004-12-13,Point Contact Spectroscopy of Superconducting Gap Anisotropy in Nickel Borocarbide Compound LuNi2B2C,"Point contacts are used to investigate the anisotropy of the superconducting
+energy gap in LuNi2B2C in the ab plane and along the c axis. It is shown that
+the experimental curves should be described assuming that the superconducting
+gap is non-uniformly distributed over the Fermi surface. The largest and the
+smallest gaps have been estimated by two-gap fitting models. It is found that
+the largest contribution to the point-contact conductivity in the c direction
+is made by a smaller gap and, in the ab plane by a larger gap. The deviation
+from the one-gap BCS model is pronounced in the temperature dependence of the
+gap in both directions. The temperature range, where the deviation occurs, is
+for the c direction approximately 1.5 times more than in the ab plane. The
+\Gamma parameter, allowing quantitatively estimate the gap anisotropy by
+one-gap fitting, in c direction is also about 1.5 times greater than in the ab
+plane. Since it is impossible to describe satisfactorily such gap distribution
+either by the one- or two-gap models, a continuous, dual-maxima model of gap
+distribution over the Fermi surface should be used to describe
+superconductivity in this material.",0412325v1
+2005-03-24,Fast magnetization switching of Stoner particles: A nonlinear dynamics picture,"The magnetization reversal of Stoner particles is investigated from the point
+of view of nonlinear dynamics within the Landau-Lifshitz-Gilbert formulation.
+The following results are obtained. 1) We clarify that the so-called
+Stoner-Wohlfarth (SW) limit becomes exact when damping constant is infinitely
+large. Under the limit, the magnetization moves along the steepest energy
+descent path. The minimal switching field is the one at which there is only one
+stable fixed point in the system. 2) For a given magnetic anisotropy, there is
+a critical value for the damping constant, above which the minimal switching
+field is the same as that of the SW-limit. 3) We illustrate how fixed points
+and their basins change under a field along different directions. This change
+explains well why a non-parallel field gives a smaller minimal switching field
+and a short switching time. 4) The field of a ballistic magnetization reversal
+should be along certain direction window in the presence of energy dissipation.
+The width of the window depends on both of the damping constant and the
+magnetic anisotropy. The upper and lower bounds of the direction window
+increase with the damping constant. The window width oscillates with the
+damping constant for a given magnetic anisotropy. It is zero for both zero and
+infinite damping. Thus, the perpendicular field configuration widely employed
+in the current experiments is not the best one since the damping constant in a
+real system is far from zero.",0503594v1
+2005-04-19,Thermodynamics of S>=1 ferromagnetic Heisenberg chains with uniaxial single-ion anisotropy,"The thermodynamic properties of S>=1 ferromagnetic chains with an easy-axis
+single-ion anisotropy are investigated at arbitrary temperatures by both a
+Green-function approach, based on a decoupling of three-spin operator products,
+and by exact diagonalizations of chains with up to N=12 sites using periodic
+boundary conditions. A good agreement between the results of both approaches is
+found. For the S=1 chain, the temperature dependence of the specific heat
+reveals two maxima, if the ratio of the anisotropy energy D and the exchange
+energy J exceeds a characteristic value, D/J >7.4, and only one maximum for D/J
+<7.4. This is in contrast to previous exact diagonalization data for comparably
+small chains (N <= 7) using open boundary conditions. Comparing the theory with
+experiments on di-bromo Ni complexes the fit to the specific heat yields
+concrete values for D and J which are used to make predictions for the
+temperature dependences of the spin-wave spectrum, the correlation length, and
+the transverse magnetic susceptibility.",0504481v2
+2005-12-21,Magnetic Anisotropy of Isolated Cobalt Nanoplatelets,"Motivated in part by experiments performed by M.H. Pan et al. (nanoletters,
+v.5, p 83, 2005), we have undertaken a theoretical study of the the magnetic
+properties of two-monolayer thick Co nanoplatelets with an equilateral
+triangular shape. The analysis is carried out using a microscopic Slater-Koster
+tight-binding model with atomic exchange and spin-orbit interactions designed
+to realistically capture the salient magnetic features of large nanoclusters
+containing up to 350 atoms. Two different truncations of the FCC lattice are
+studied, in which the nanoplatelet surface is aligned parallel to the FCC (111)
+and (001)crystal planes respectively. We find that the higher coordination
+number in the (111) truncated crystal is more likely to reproduce the
+perpendicular easy direction found in experiment. Qualitatively, the most
+important parameter governing the anisotropy of the model is found to be the
+value of the intra-atomic exchange integral J. If we set the value of J near
+the bulk value in order to reproduce the experimentally observed magnitude of
+the magnetic moments, we find both quasi-easy-planes and perpendicular easy
+directions. At larger values of J we find that the easy-axis of magnetization
+is perpendicular to the surface, and the value of the magnetic anisotropy
+energy per atom is larger. The possible role of hybridization with substrate
+surface states in the experimental systems is discussed.",0512523v2
+2006-02-07,Magnetic excitations and their anisotropy in YBCO: slave-boson mean-field analysis of bilayer t-J model,"We perform a comprehensive analysis of the dynamical magnetic susceptibility
+\chi(q,\omega) in the slave-boson mean-field scheme of the bilayer t-J model.
+In the d-wave pairing state, the strongest magnetic spectral weight appears at
+q=Q=(pi,pi) and \omega=\omega_{Q}^{res}, and spreads into a diamond-shaped
+shell around Q in q space for \omega<\omega_{Q}^{res}. This weight is due to a
+collective mode, namely a particle-hole bound state, which has a downward
+\omega versus q dispersion around Q. Within the high intensity shell, the
+incommensurate (IC) signals at q=(pi,pi\pm 2pi\eta) and (pi\pm 2pi\eta,pi) tend
+to be stronger than the diagonal incommensurate (DIC) signals at q=(pi\pm
+2pi\eta',pi\pm 2pi\eta'), especially for a large hole density \delta. For
+\omega \ll \omega_{Q}^{res} the IC signals completely disappear and the weight
+remains only around the DIC positions. For \omega > \omega_{Q}^{res} strong
+signals of Im\chi(q,\omega) tracing an upward dispersion are found and
+interpreted as an overdamped collective mode near \omega_{Q}^{res}. In the
+normal state, Im\chi(q,\omega) has a broad peak at q=Q. That is, the IC and DIC
+signals appear only in the d-wave pairing state. We also study effects of a
+small orthorhombic anisotropy, which is intrinsic in untwinned YBCO crystals.
+Because of electron-electron correlations favoring d-wave shaped Fermi surface
+deformations (dFSD), we expect an enhanced anisotropy of magnetic excitation
+spectra. This effect is particularly pronounced for low \delta and at
+relatively high temperature. The present theory provides a rather detailed
+microscopic explanation of the most salient properties of magnetic excitations
+observed in YBCO.",0602189v1
+2006-02-16,"Magnetic properties and domain structure of (Ga,Mn)As films with perpendicular anisotropy","The ferromagnetism of a thin GaMnAs layer with a perpendicular easy
+anisotropy axis is investigated by means of several techniques, that yield a
+consistent set of data on the magnetic properties and the domain structure of
+this diluted ferromagnetic semiconductor. The magnetic layer was grown under
+tensile strain on a relaxed GaInAs buffer layer using a procedure that limits
+the density of threading dislocations. Magnetometry, magneto-transport and
+polar magneto-optical Kerr effect (PMOKE) measurements reveal the high quality
+of this layer, in particular through its high Curie temperature (130 K) and
+well-defined magnetic anisotropy. We show that magnetization reversal is
+initiated from a limited number of nucleation centers and develops by easy
+domain wall propagation. Furthermore, MOKE microscopy allowed us to
+characterize in detail the magnetic domain structure. In particular we show
+that domain shape and wall motion are very sensitive to some defects, which
+prevents a periodic arrangement of the domains. We ascribed these defects to
+threading dislocations emerging in the magnetic layer, inherent to the growth
+mode on a relaxed buffer.",0602388v2
+2006-09-26,Competing impurities and reentrant magnetism in La(2-x)Sr(x)Cu(1-z)Zn(z)O(4) revisited. The role of the Dzyaloshinskii-Moriya and XY anisotropies,"We study the order-from-disorder transition and reentrant magnetism in
+La(2-x)Sr(x)Cu(1-z)Zn(z)O(4) within the framework of a long-wavelength
+nonlinear sigma model that properly incorporates the Dzyaloshinskii-Moriya and
+XY anisotropies. Doping with nonmagnetic impurities, such as Zn, is considered
+according to classical percolation theory, whereas the effect of Sr, which
+introduces charge carriers into the CuO(2) planes, is described as a dipolar
+frustration of the antiferromagnetic order. We calculate several magnetic,
+thermodynamic, and spectral properties of the system, such as the
+antiferromagnetic order parameter, the Neel temperature, the spin-stiffness,
+and the anisotropy gaps, as well as their evolution with both Zn and Sr doping.
+We explain the nonmonotonic and reentrant behavior experimentally observed for
+T_N by Hucker et al. in Phys. Rev. B 59, R725 (1999), as resulting from the
+reduction, due to the nonmagnetic impurities, of the dipolar frustration
+induced by the charge carriers (order-from-disorder). Furthermore, we find a
+similar nonmonotonic and reentrant behavior for all the other observables
+studied. Most remarkably, our results show that while for x=2% and z=0 the
+Dzyaloshinskii-Moriya gap \Delta_{DM}=0, for z=15% it is approximately
+\Delta_{DM} = 7.5 cm^(-1). The later is larger than the lowest low-frequency
+cutoff for Raman spectroscopy (~ 5 cm^(-1)), and could thus be observed in
+one-magnon Raman scattering.",0609653v1
+2007-01-22,Influence of Point-like Disorder on the Guiding of Vortices and the Hall Effect in a Washboard Planar Pinning Potential,"Explicit current-dependent expressions for anisotropic longitudinal and
+transverse nonlinear magnetoresistivities are represented and analyzed on the
+basis of a Fokker-Planck approach for two-dimensional single-vortex dynamics in
+a washboard pinning potential in the presence of point-like disorder. Graphical
+analysis of the resistive responses is presented both in the current-angle
+coordinates and in the rotating current scheme. The model describes nonlinear
+anisotropy effects caused by the competition of point-like (isotropic) and
+anisotropic pinning. Nonlinear guiding effects are discussed and the critical
+current anisotropy is analyzed. Gradually increasing the magnitude of isotropic
+pinning force this theory predicts a gradual decrease of the anisotropy of the
+magnetoresistivities. The physics of transition from the new scaling relations
+for anisotropic Hall resistance in the absence of point-like pins to the
+well-known scaling relations for the point-like disorder is elucidated. This is
+discussed in terms of a gradual isotropizaton of the guided vortex motion,
+which is responsible for the existence in a washboard pinning potential of new
+(with respect to magnetic field reversal) Hall voltages. It is shown that
+whereas the Hall conductivity is not changed by pinning, the Hall resistivity
+can change its sign in some current-angle range due to presence of the
+competition between i- and a-pins.",0701530v1
+2007-03-05,Rotator and extender ferroelectrics: Importance of the shear coefficient to the piezoelectric properties of domain-engineered crystals and ceramics,"The importance of a high shear coefficient d15 (or d24) to the piezoelectric
+properties of domain-engineered and polycrystalline ferroelectrics is
+discussed. The extent of polarization rotation, as a mechanism of piezoelectric
+response, is directly correlated to the shear coefficient. The terms ""rotator""
+and ""extender"" are introduced to distinguish the contrasting behaviors of
+crystals such as 4mm BaTiO3 and PbTiO3. In ""rotator"" ferroelectrics, where d15
+is high relative to the longitudinal coefficient d33, polarization rotation is
+the dominant mechanism of piezoelectric response; the maximum longitudinal
+piezoelectric response is found away from the polar axis. In ""extender""
+ferroelectrics, d15 is low and the collinear effect dominates; the maximum
+piezoelectric response is found along the polar axis. A variety of 3m, mm2 and
+4mm ferroelectrics, with various crystal structures based on oxygen octahedra,
+are classified in this way. It is shown that the largest piezoelectric
+anisotropies d15/d33 are always found in 3m crystals; this is a result of the
+intrinsic electrostrictive anisotropy of the constituent oxygen octahedra.
+Finally, for a given symmetry, the piezoelectric anisotropy increases close to
+ferroelectric-ferroelectric phase transitions; this includes morphotropic phase
+boundaries and temperature induced polymorphic transitions.",0703121v1
+2007-03-13,Online Supplementary Material: Low temperature vortex liquid in $\rm La_{2-x}Sr_xCuO_4$,"We report here the supplementary material for Ref. [1]. Using torque
+magnetometry, we measured the magnetization anisotropy of 7 crystals of $\rm
+La_{2-x}Sr_xCuO_4$ (LSCO). In optimally-doped cuprates, the bulk susceptibility
+is dominated by the paramagnetic van-Vleck orbital term $\chi_{orb}$ which has
+a significant anisotropy ($\chi^{orb}_c>\chi^{orb}_{ab}$) that changes weakly
+with $T$ (subscripts $c$ and ${ab}$ identify quantities measured with $\bf
+H||c$ and $\bf H\perp c$, respectively). Moreover, in the lightly-doped regime,
+the paramagnetic spin susceptibilities $\chi^s_c$ and $\chi^s_{ab}$ become
+significantly large below the interval 40-60 K. However, the spin
+susceptibility is very nearly isotropic (except below 10 K where its anisotropy
+becomes measurable). Against the large orbital and spin terms, the weak
+diamagnetic signal is very difficult to resolve using standard bulk
+magnetometry in lightly-doped cuprates. By contrast, torque magnetometry
+selectively detects the orbital diamagnetism generated by supercurrents
+confined to the CuO$_2$ layers while ignoring the large spin contribution when
+it is isotropic. The orbital van-Vleck contribution is also detected, but as a
+``background'' that is $H$-linear to intense fields and only mildly $T$
+dependent.",0703348v1
+2007-03-28,Stability of Biaxial Nematic Phase for Systems with Variable Molecular Shape Anisotropy,"We study the influence of fluctuations in molecular shape on the stability of
+the biaxial nematic phase by generalizing the mean field model of Mulder and
+Ruijgrok [Physica A {\bf 113}, 145 (1982)]. We limit ourselves to the case when
+the molecular shape anisotropy, represented by the alignment tensor, is a
+random variable of an annealed type. A prototype of such behavior can be found
+in lyotropic systems - a mixture of potassium laurate, 1-decanol, and $D_2O$,
+where distribution of the micellar shape adjusts to actual equilibrium
+conditions. Further examples of materials with the biaxial nematic phase, where
+molecular shape is subject to fluctuations, are thermotropic materials composed
+of flexible trimeric- or tetrapod-like molecular units. Our calculations show
+that the Gaussian equilibrium distribution of the variables describing
+molecular shape (dispersion force) anisotropy gives rise to new classes of the
+phase diagrams, absent in the original model. Depending on properties of the
+shape fluctuations, the stability of the biaxial nematic phase can be either
+enhanced or depressed, relative to the uniaxial nematic phases. In the former
+case the splitting of the Landau point into two triple points with a direct
+phase transition line from isotropic to biaxial phase is observed.",0703736v2
+2000-01-20,Locally Anisotropic Kinetic Processes and Thermodynamics in Curved Spaces,"The kinetic theory is formulated with respect to anholonomic frames of
+reference on curved spacetimes. By using the concept of nonlinear connection we
+develop an approach to modelling locally anisotropic kinetic processes and, in
+corresponding limits, the relativistic non-equilibrium thermodynamics with
+local anisotropy. This lead to a unified formulation of the kinetic equations
+on (pseudo) Riemannian spaces and in various higher dimensional models of
+Kaluza-Klein type and/or generalized Lagrange and Finsler spaces. The
+transition rate considered for the locally anisotropic transport equations is
+related to the differential cross section and spacetime parameters of
+anisotropy. The equations of states for pressure and energy in locally
+anisotropic thermodynamics are derived. The obtained general expressions for
+heat conductivity, shear and volume viscosity coefficients are applied to
+determine the transport coefficients of cosmic fluids in spacetimes with
+generic local anisotropy. We emphasize that such locally anisotropic structures
+are induced also in general relativity if we are modelling physical processes
+with respect to frames with mixed sets of holonomic and anholonomic basis
+vectors which naturally admits an associated nonlinear connection structure.",0001060v3
+2005-03-01,Primordial magnetic seed field amplification by gravitational waves,"Using second-order gauge-invariant perturbation theory, a self-consistent
+framework describing the non-linear coupling between gravitational waves and a
+large-scale homogeneous magnetic field is presented. It is shown how this
+coupling may be used to amplify seed magnetic fields to strengths needed to
+support the galactic dynamo. In situations where the gravitational wave
+background is described by an `almost' Friedmann-Lema{\^i}tre-Robertson-Walker
+(FLRW) cosmology we find that the magnitude of the original magnetic field is
+amplified by an amount proportional to the magnitude of the gravitational wave
+induced shear anisotropy and the square of the field's initial co-moving scale.
+We apply this mechanism to the case where the seed field and gravitational wave
+background are produced during inflation and find that the magnitude of the
+gravitational boost depends significantly on the manner in which the estimate
+of the shear anisotropy at the end of inflation is calculated. Assuming a seed
+field of $10^{-34}$ $\rm{G}$ spanning a comoving scale of about $10 \rm{kpc}$
+today, the shear anisotropy at the end of inflation must be at least as large
+as $10^{-40}$ in order to obtain a generated magnetic field of the same order
+of magnitude as the original seed. Moreover, contrasting the weak field
+approximation to our gauge-invariant approach, we find that while both methods
+agree in the limit of high conductivity, their corresponding solutions are
+otherwise only compatible in the limit of infinitely long-wavelength
+gravitational waves.",0503006v2
+2003-02-28,Two flavors of dynamical quarks on anisotropic lattices,"We report on our study of two-flavor full QCD on anisotropic lattices using
+$O(a)$-improved Wilson quarks coupled with an RG-improved glue. The bare gauge
+and quark anisotropies corresponding to the renormalized anisotropy
+$\xi=a_s/a_t = 2$ are determined as functions of $\beta$ and $\kappa$, which
+covers the region of spatial lattice spacings $a_s\approx 0.28$--0.16 fm and
+$m_{PS}/m_V\approx 0.6$--0.9. The calibrations of the bare anisotropies are
+performed with the Wilson loop and the meson dispersion relation at 4 lattice
+cutoffs and 5--6 quark masses. Using the calibration results we calculate the
+meson mass spectrum and the Sommer scale $r_0$. We confirm that the values of
+$r_0$ calculated for the calibration using pseudo scalar and vector meson
+energy momentum dispersion relation coincide in the continuum limit within
+errors. This work serves to lay ground toward studies of heavy quark systems
+and thermodynamics of QCD including the extraction of the equation of state in
+the continuum limit using Wilson-type quark actions.",0302024v2
+1993-03-19,Post-COBE predictions for Inflationary Gravity Wave and Density Perturbation spectra,"We assess the relative contribution to the COBE - measured microwave
+anisotropy arising both from relic gravity waves as well as primordial density
+perturbations originating during inflation. We show that the gravity wave
+contribution to the CMBR anisotropy depends sensitively upon $n$ -- the
+primordial spectral index ($\dk^2 \propto k^n$), increasing as $n$ deviates
+from a Harrison - Zeldovich spectrum (n = 1). As a result, for $n < 0.84$ the
+contribution from gravity waves towards $\delta T/ T $ is greater than the
+corresponding contribution from density perturbations, whereas for $n > 0.84$
+the reverse is true. ($ n = 0.84$ corresponds to an expansion index $p = 13.5$
+in models with power-law inflation $a \propto t^p$. ) Our results show that for
+a scale-invariant Harrison-Zeldovich spectrum generated by chaotic inflation,
+gravity waves contribute approximately $24\%$ to the CMBR anisotropy measured
+by COBE. Applying our results to the cold dark matter scenario for galaxy
+formation, we find that in general CDM models with tilted power spectra ($n <
+1$), require the biasing parameter to be greater than unity, on scales of
+$16h_{50}^{-1} Mpc$. We also obtain an expression for the COBE - normalised
+amplitude and spectrum of the stochastic gravity wave background and compare it
+with the sensitivity of planned laser-interferometer gravity wave detectors.",9303285v1
+1999-09-17,Microwave background anisotropies and large scale structure constraints on isocurvature modes in a two-field model of inflation,"In this paper we study the isocurvature mode contribution to the cosmic
+microwave background anisotropies and the large scale structure power spectrum,
+for a two-field model of inflation proposed by Linde and Mukhanov. We provide
+constraints on the parameters of the model by comparing its predictions with
+observations of the microwave background anisotropies, large scale structure
+data on the galaxy power spectrum, and the number density of nearby galaxy
+clusters. We find that such models are consistent with observations for a
+narrow range of parameters. As our main result, we find that only a very small
+isocurvature component is allowed, $\al \le 0.006$, for any underlying
+Friedmann model. Furthermore, we give the expected resolution with which the
+model parameters will be determined from future satellite missions like MAP and
+Planck, for a fiducial flat $\Lambda$CDM model. We find that Planck mission
+will be able to detect such small contributions, especially if polarization
+information is included. The isocurvature spectral index $\niso$ will also be
+determined with better than 8% precision.",9909420v2
+2003-08-07,On the origin of the large scale structures of the universe,"We revise the statistical properties of the primordial cosmological density
+anisotropies that, at the time of matter radiation equality, seeded the
+gravitational development of large scale structures in the, otherwise,
+homogeneous and isotropic Friedmann-Robertson-Walker flat universe. Our
+analysis shows that random fluctuations of the density field at the same
+instant of equality and with comoving wavelength shorter than the causal
+horizon at that time can naturally account, when globally constrained to
+conserve the total mass (energy) of the system, for the observed scale
+invariance of the anisotropies over cosmologically large comoving volumes.
+Statistical systems with similar features are generically known as glass-like
+or lattice-like. Obviously, these conclusions conflict with the widely accepted
+understanding of the primordial structures reported in the literature, which
+requires an epoch of inflationary cosmology to precede the standard expansion
+of the universe. The origin of the conflict must be found in the widespread,
+but unjustified, claim that scale invariant mass (energy) anisotropies at the
+instant of equality over comoving volumes of cosmological size, larger than the
+causal horizon at the time, must be generated by fluctuations in the density
+field with comparably large comoving wavelength.",0308078v5
+2004-08-27,Progress in Anisotropic Plasma Physics,"In 1959 Weibel demonstrated that when a QED plasma has a temperature
+anisotropy there exist unstable transverse magnetic excitations which grow
+exponentially fast. In this paper we will review how to determine the growth
+rates for these unstable modes in the weak-coupling and ultrarelativistic
+limits in which the collective behavior is describable in terms are so-called
+""hard-loops"". We will show that in this limit QCD is subject to instabilities
+which are analogous to the Weibel instability in QED. The presence of such
+instabilities dominates the early time evolution of a highly anisotropic
+plasma; however, at longer times it is expected that these instabilities will
+saturate (condense). I will discuss how the presence of non-linear interactions
+between the gluons complicates the determination of the saturated state. In
+order to discuss this I present the generalization of the Braaten-Pisarski
+isotropic hard-thermal-loop effective action to a system with a temperature
+anisotropy in the parton distribution functions. The resulting hard-loop
+effective action can be used to determine the time and energy scales associated
+with the possible saturation (condensation) of the gluonic modes. We will also
+discuss the effects of anisotropies on observables, in particular on the heavy
+quark energy loss.",0408314v2
+1998-06-12,Limit on suppression of ionization in metastable neon traps due to long-range anisotropy,"This paper investigates the possibility of suppressing the ionization rate in
+a magnetostatic trap of metastable neon atoms by spin-polarizing the atoms.
+Suppression of the ionization is critical for the possibility of reaching
+Bose-Einstein condensation with such atoms. We estimate the relevant long-range
+interactions for the system, consisting of electric quadrupole-quadrupole and
+dipole-induced dipole terms, and develop short-range potentials based on the
+Na_2 singlet and triplet potentials. The auto-ionization widths of the system
+are also calculated. With these ingredients we calculate the ionization rate
+for spin-polarized and for spin-isotropic samples, caused by anisotropy of the
+long-range interactions. We find that spin-polarization may allow for four
+orders of magnitude suppression of the ionization rate for Ne. The results
+depend sensitively on a precise knowledge of the interaction potentials,
+however, pointing out the need for experimental input. The same model gives a
+suppression ratio close to unity for metastable xenon in accordance with
+experimental results, due to a much increased anisotropy in this case.",9806018v1
+2004-04-22,Small scale structure of homogeneous turbulent shear flow,"The structure of homogeneous turbulent shear flow is studied using data
+generated by Direct Numerical Simulations (DNS) and a linear analysis for both
+compressible and incompressible cases. At large values of the mean shear rate,
+the Rapid Distortion Theory (RDT) limit is approached. Analytical solutions are
+found for the inviscid compressible RDT equations at long times. The RDT
+equations are also solved numerically for both inviscid and viscous cases. The
+RDT solutions, confirmed by the DNS results, show that the even order
+transverse derivative moments of the dilatational and solenoidal velocity
+fields are anisotropic, with the dilatational motions more anisotropic than
+their solenoidal counterparts. The results obtained for the incompressible case
+are similar to those obtained for the solenoidal motions in the compressible
+case. The DNS results also indicate an increase in the anisotropy of the even
+order transverse derivative moments with the order of the moment, in agreement
+with the RDT predictions. Although the anisotropy decreases with Reynolds
+number, it is likely that for higher even order moments it will persist at
+large values of the Reynolds number, in contrast with the postulate of local
+isotropy. The RDT solutions also predict that the normalized odd order
+transverse derivative moments of the solenoidal velocity for the compressible
+case and of the velocity for the incompressible case should approach a constant
+different than zero at large times. This prediction is supported by the DNS
+data. For higher odd order normalized moments, the RDT analysis suggests that
+the anisotropy may persist at large values of the Reynolds number, in agreement
+with the existent experimental data.",0404108v1
+2006-11-27,Generando entrelazamiento en cadenas XY - (Generating entanglement in XY chains),"Se estudia en este trabajo la capacidad de generar entrelazamiento de una
+cadena de espines con acoplamiento de Heisenberg XY y un campo magnetico
+uniforme a partir de un estado inicial en el que los espines estan
+completamente alineados. Se encuentra que la capacidad de generar estados
+entrelazados no muestra un comportamiento monotono con el campo presentando, en
+cambio, plateaus y resonancias. Tambien se muestra que, a pesar de que la
+anisotropia es necesaria para que se generen estados entrelazados, una mayor
+anisotropia no implica necesariamente mejores condiciones para generar
+entrelazamiento que sirva para usarse en una computadora cuantica. Inclusive,
+se observa que, se genera una cantidad finita de entrelazamiento en el limite
+de pequena anisotropia.
+  (The maximum entanglement reached by an initially fully aligned state
+evolving in a XY Heisenberg spin chain placed in a uniform transverse magnetic
+field is studied. It is shown that the capacity to create entangled states
+(both of one qubit with the rest of the chain and pairwise between two adjacent
+qubits) is not a monotonous function of the magnetic field: it presents
+plateaus and resonances. It is also shown that, though anisotropy in the
+interaction is necessary for entanglement generation, the best conditions for
+generating entanglement that may be suitable for use in quantum computation is
+not that of biggest anisotropy. Moreover finite amounts of entanglement are
+generated in the small anisotropy limit.)",0611258v1
+2007-04-11,Anisotropy and Magnetic Field Effects on the Genuine Multipartite Entanglement of Multi-Qubit Heisenberg {\it XY} Chains,"It has been shown that, for the two-qubit Heisenberg XY model, anisotropy and
+magnetic field may together be used to produce entanglement for any finite
+temperature by adjusting the external magnetic field beyond some finite
+critical strength. This interesting result arises from an analysis employing
+the Wootters concurrence, a computable measure of entanglement for two-qubit
+states. Recently, Mintert {\em et al.} proposed generalizations of Wootters
+concurrence for multipartite states. These MKB concurrences possess a
+mathematical property that enables one to understand the origin of this
+characteristic behavior. Here, we first study the effect of anisotropy and
+magnetic field on the multipartite thermal entanglement of a four-qubit
+Heisenberg XY chain using the MKB concurrences. We show that this model
+exhibits characteristic behavior similar to that of the two-qubit model. In
+addition, we show that this can again be understood using the same mathematical
+property. Next, we show that the six-qubit Heisenberg XY chain possesses
+properties necessary for it to have the characteristic behavior too. Most
+importantly, it is possible to directly measure the multipartite MKB
+concurrences of pure states. This may provide an experimental verification of
+our conjecture that for a Heisenberg XY chain of any even number of qubits, it
+is always possible to obtain non-zero genuine multipartite entanglement at any
+finite temperature by applying a sufficiently large magnetic field.",0704.1368v2
+2007-04-19,On Larkin-Imry-Ma State of 3He-A in Aerogel,"Superfluid 3He-A shares the properties of spin nematic and chiral orbital
+ferromagnet. Its order parameter is characterized by two vectors d and l. This
+doubly anisotropic superfluid, when it is confined in aerogel, represents the
+most interesting example of a system with continuous symmetry in the presence
+of random anisotropy disorder. We discuss the Larkin-Imry-Ma state, which is
+characterized by the short-range orientational order of the vector l, while the
+long-range orientational order is destroyed by the collective action of the
+randomly oriented aerogel strings. On the other hand, sufficiently large
+regular anisotropy produced either by the deformation of the aerogel or by
+applied superflow suppresses the Larkin-Imry-Ma effect leading to the uniform
+orientation of the vector l. This interplay of regular and random anisotropy
+allows us to study many different effects.",0704.2484v10
+2007-04-23,What it takes to measure a fundamental difference between dark matter and baryons: the halo velocity anisotropy,"Numerous ongoing experiments aim at detecting WIMP dark matter particles from
+the galactic halo directly through WIMP-nucleon interactions. Once such a
+detection is established a confirmation of the galactic origin of the signal is
+needed. This requires a direction-sensitive detector. We show that such a
+detector can measure the velocity anisotropy beta of the galactic halo.
+Cosmological N-body simulations predict the dark matter anisotropy to be
+nonzero, beta~0.2. Baryonic matter has beta=0 and therefore a detection of a
+nonzero beta would be strong proof of the fundamental difference between dark
+and baryonic matter. We estimate the sensitivity for various detector
+configurations using Monte Carlo methods and we show that the strongest signal
+is found in the relatively few high recoil energy events. Measuring beta to the
+precision of ~0.03 will require detecting more than 10^4 WIMP events with
+nuclear recoil energies greater than 100 keV for a WIMP mass of 100 GeV and a
+32S target. This number corresponds to ~10^6 events at all energies. We discuss
+variations with respect to input parameters and we show that our method is
+robust to the presence of backgrounds and discuss the possible improved
+sensitivity for an energy-sensitive detector.",0704.2909v3
+2007-04-25,Revisiting the effect of nearby supernova remnants on local cosmic rays,"In an earlier paper, the effect of the nearby known supernova remnants (SNRs)
+on the local cosmic-rays (CRs) was studied, considering different possible
+forms of the particle injection time. The present work is a continuation of the
+previous work, but assumes a more realistic model of CR propagation in the
+Galaxy. The previous work assumed an unbounded three-dimensional diffusion
+region, whereas the present one considers a flat cylindrical disc bounded in
+both the radial and vertical directions. The study has found that the effect of
+the vertical halo boundary $H$ on the local SNR contribution to the observed CR
+anisotropy is negligible as long as $H\gtrsim 2kpc$. Considering the values of
+the halo height $H\gtrsim 2kpc$ obtained by different authors, the present work
+suggests that the study of the effect of local sources on the CR anisotropy can
+be carried out without having much information on $H$ and hence, using the much
+simpler three-dimentional unbounded solution. Finally, the present work
+discusses about the possibility of explaining the observed anisotropy below the
+knee by a single dominant source with properly chosen source parameters, and
+claims that the source may be an \textit{undetected} old SNR with a
+characteristic age of $\sim 1.5\times 10^5 yr$ located at a distance of $\sim
+0.57 kpc$ from the Sun.",0704.3336v2
+2007-07-05,Theory of cosmological perturbations in an anisotropic universe,"This article describes the theory of cosmological perturbations around a
+homogeneous and anisotropic universe of the Bianchi I type. Starting from a
+general parameterisation of the perturbed spacetime a la Bardeen, a complete
+set of gauge invariant variables is constructed. Three physical degrees of
+freedom are identified and it is shown that, in the case where matter is
+described by a scalar field, they generalize the Mukhanov-Sasaki variables. In
+order to show that they are canonical variables, the action for the
+cosmological perturbations at second order is derived. Two major physical
+imprints of the primordial anisotropy are identified: (1) a scalar-tensor
+``see-saw'' mechanism arising from the fact that scalar, vector and tensor
+modes do not decouple and (2) an explicit dependence of the statistical
+properties of the density perturbations and gravity waves on the wave-vector
+instead of its norm. This analysis extends, but also sheds some light on, the
+quantization procedure that was developed under the assumption of a
+Friedmann-Lemaitre background spacetime, and allows to investigate the
+robustness of the predictions of the standard inflationary scenario with
+respect to the hypothesis on the symmetries of the background spacetime. These
+effects of a primordial anisotropy may be related to some anomalies of the
+cosmic microwave background anisotropies on large angular scales.",0707.0736v1
+2007-07-12,Superorbital variability of X-ray and radio emission of Cyg X-1. I. Emission anisotropy of precessing sources,"We study theoretical interpretations of the 150-d (superorbital) modulation
+observed in X-ray and radio emission of Cyg X-1 in the framework of models
+connecting this phenomenon to precession. Precession changes the orientation of
+the emission source (either disc or jet) relative to the observer. This leads
+to emission modulation due to an anisotropic emission pattern of the source or
+orientation-dependent amount of absorbing medium along the line of sight or
+both. We consider, in particular, anisotropy patterns of blackbody-type
+emission, thermal Comptonization in slab geometry, jet/outflow beaming, and
+absorption in a coronal-type medium above the disc. We then fit these models to
+the data from the RXTE/ASM, CGRO/BATSE, and the Ryle and Green Bank radio
+telescopes, and find relatively small best-fit angles between the precession
+and orbital planes, ~10-20 degrees. The thermal Comptonization model for the
+X-ray emission explains well the observed decrease of the variability amplitude
+from 1 to 300 keV as a result of a reduced anisotropy of the emission due to
+multiple scatterings. Our modeling also yield the jet bulk velocity of
+~(0.3-0.5)c, which is in agreement with the previous constraint from the lack
+of an observed counterjet and lack of short-term X-ray/radio correlations.",0707.1880v1
+2007-08-07,Systematic {\it ab initio} study of the magnetic and electronic properties of all 3d transition metal linear and zigzag nanowires,"It is found that all the zigzag chains except the nonmagnetic (NM) Ni and
+antiferromagnetic (AF) Fe chains which form a twisted two-legger ladder, look
+like a corner-sharing triangle ribbon, and have a lower total energy than the
+corresponding linear chains. All the 3d transition metals in both linear and
+zigzag structures have a stable or metastable ferromagnetic (FM) state. The
+electronic spin-polarization at the Fermi level in the FM Sc, V, Mn, Fe, Co and
+Ni linear chains is close to 90% or above. In the zigzag structure, the AF
+state is more stable than the FM state only in the Cr chain. It is found that
+the shape anisotropy energy may be comparable to the electronic one and always
+prefers the axial magnetization in both the linear and zigzag structures. In
+the zigzag chains, there is also a pronounced shape anisotropy in the plane
+perpendicular to the chain axis. Remarkably, the axial magnetic anisotropy in
+the FM Ni linear chain is gigantic, being ~12 meV/atom. Interestingly, there is
+a spin-reorientation transition in the FM Fe and Co linear chains when the
+chains are compressed or elongated. Large orbital magnetic moment is found in
+the FM Fe, Co and Ni linear chains.",0708.0973v1
+2007-10-02,SAURON's Challenge for the Major Merger Scenario of Elliptical Galaxy Formation,"The intrinsic anisotropy delta and flattening epsilon of simulated merger
+remnants is compared with elliptical galaxies that have been observed by the
+SAURON collaboration, and that were analysed using axisymmetric Schwarzschild
+models. Collisionless binary mergers of stellar disks and disk mergers with an
+additional isothermal gas component, neglecting star formation cannot reproduce
+the observed trend delta = 0.55 epsilon (SAURON relationship). An excellent fit
+of the SAURON relationship for flattened ellipticals with epsilon >= 0.25 is
+however found for merger simulations of disks with gas fractions >= 20%,
+including star formation and stellar energy feedback. Massive black hole
+feedback does not strongly affect this result. Subsequent dry merging of merger
+remnants however does not generate the slowly-rotating SAURON ellipticals which
+are characterized by low ellipticities epsilon < 0.25 and low anisotropies.
+This indicates that at least some ellipticals on the red galaxy sequence did
+not form by binary mergers of disks or early-type galaxies. We show that
+stellar spheroids resulting from multiple, hierarchical mergers of
+star-bursting subunits in a cosmological context are in excellent agreement
+with the low ellipticities and anisotropies of the slowly rotating SAURON
+ellipticals and their observed trend of delta with epsilon. The numerical
+simulations indicate that the SAURON relation might be a result of strong
+violent relaxation and phase mixing of multiple, kinematically cold stellar
+subunits with the angular momentum of the system determining its location on
+the relation.",0710.0663v1
+2007-10-12,Magnetism and effect of anisotropy with one dimensional monatomic chain of cobalt by a Monte Carlo simulation,"The magnetic properties of the one dimensional (1D) monatomic chain of Co
+reported in a previous experimental work are investigated by a classical Monte
+Carlo simulation based on the anisotropic Heisenberg model. In our simulation,
+the effect of the on-site uniaxial anisotropy, Ku, on each individual Co atom
+and the nearest neighbour exchange interaction, J, are accounted for. The
+normalized coercivity HC(T)/HC(TCL) is found to show a universal behaviour,
+HC(T)/HC(TCL) = h0(e^{TB/T}-e) in the temperature interval, TCL < T < TBCal,
+arising from the thermal activation effect. In the above expression, h0 is a
+constant, TBCal is the blocking temperature determined by the calculation, and
+TCL is the temperature above which the classical Monte Carlo simulation gives a
+good description on the investigated system. The present simulation has
+reproduced the experimental features, including the temperature dependent
+coercivity, HC(T), and the angular dependence of the remanent magnetization,
+MR(phi,theta), upon the relative orientation (phi,theta) of the applied field
+H. In addition, the calculation reveals that the ferromagnetic-like open
+hysteresis loop is a result of a slow dynamical process at T < TBCal. The
+dependence of the dynamical TBCal on the field sweeping rate R, the on-site
+anisotropy constant Ku, and the number of atoms in the atomic chain, N, has
+been investigated in detail.",0710.2381v1
+2007-10-23,Angular Signatures of Annihilating Dark Matter in the Cosmic Gamma-Ray Background,"The extragalactic cosmic gamma-ray background (CGB) is an interesting channel
+to look for signatures of dark matter annihilation. In particular, besides the
+imprint in the energy spectrum, peculiar anisotropy patterns are expected
+compared to the case of a pure astrophysical origin of the CGB. We take into
+account the uncertainties in the dark matter clustering properties on
+sub-galactic scales, deriving two possible anisotropy scenarios. A clear dark
+matter angular signature is achieved when the annihilation signal receives only
+a moderate contribution from sub-galactic clumps and/or cuspy haloes.
+Experimentally, if galactic foregrounds systematics are efficiently kept under
+control, the angular differences are detectable with the forthcoming GLAST
+observatory, provided that the annihilation signal contributes to the CGB for a
+fraction >10-20%. If, instead, sub-galactic structures have a more prominent
+role, the astrophysical and dark matter anisotropies become degenerate,
+correspondingly diluting the DM signature. As complementary observables we also
+introduce the cross-correlation between surveys of galaxies and the CGB and the
+cross-correlation between different energy bands of the CGB and we find that
+they provide a further sensitive tool to detect the dark matter angular
+signatures.",0710.4136v2
+2007-11-12,Cosmic microwave anisotropies from BPS semilocal strings,"We present the first ever calculation of cosmic microwave background CMB
+anisotropy power spectra from semilocal cosmic strings, obtained via
+simulations of a classical field theory. Semilocal strings are a type of
+non-topological defect arising in some models of inflation motivated by
+fundamental physics, and are thought to relax the constraints on the symmetry
+breaking scale as compared to models with (topological) cosmic strings. We
+derive constraints on the model parameters, including the string tension
+parameter mu, from fits to cosmological data, and find that in this regard BPS
+semilocal strings resemble global textures more than topological strings. The
+observed microwave anisotropy at l = 10 is reproduced if Gmu = 5.3x10^{-6} (G
+is Newton's constant). However as with other defects the spectral shape does
+not match observations, and in models with inflationary perturbations plus
+semilocal strings the 95% confidence level upper bound is Gmu<2.0x10^{-6} when
+CMB data, Hubble Key Project and Big Bang Nucleosynthesis data are used (c.f.
+Gmu<0.9x10^{-6} for cosmic strings). We additionally carry out a Bayesian model
+comparison of several models with and without defects, showing models with
+defects are neither conclusively favoured nor disfavoured at present.",0711.1842v2
+2007-11-12,Cosmic Covariance and the Low Quadrupole Anisotropy of the Wilkinson Microwave Anisotropy Probe (WMAP) Data,"The quadrupole power of cosmic microwave background (CMB) temperature
+anisotropies seen in the WMAP data is puzzlingly low. In this paper we
+demonstrate that Minimum Variance Optimization (MVO), a technique used by many
+authors (including the WMAP science team) to separate the CMB from
+contaminating foregrounds, has the effect of forcing the extracted CMB map to
+have zero statistical correlation with the foreground emission. Over an
+ensemble of universes the true CMB and foreground are indeed expected to be
+uncorrelated, but any particular sky pattern (such as the one we happen to
+observe) will generate non-zero measured correlations simply by chance. We call
+this effect ""cosmic covariance"" and it is a possible source of bias in the CMB
+maps cleaned using the MVO technique. We show that the presence of cosmic
+covariance is expected to artificially suppress the variance of the Internal
+Linear Combination (ILC) map obtained via MVO. It also propagates into the
+multipole expansion of the ILC map, generating a quadrupole deficit with more
+than 90% confidence. Since we do not know the CMB and the foregrounds a priori,
+there is therefore an unknown contribution to the uncertainty in the measured
+quadrupole power, over and above the usual cosmic variance contribution. Using
+the MVO on a series of Monte Carlo simulations that assume Gaussian CMB
+fluctuations, we estimate that the real quadrupole power of the CMB lies in the
+range [305.16,400.40] microKelvin^2 (at the 1-sigma level).",0711.1860v1
+2008-01-17,Thermodynamic quantum crtical behavior in the anisotropic Kondo necklace model,"The Ising-like anisotropy parameter $\delta$ in the Kondo necklace model is
+analyzed using the bond-operator method at zero and finite temperatures for
+arbitrary $d$ dimensions. A decoupling scheme on the double time Green's
+functions is used to find the dispersion relation for the excitations of the
+system. At zero temperature and in the paramagnetic side of the phase diagram,
+we determine the spin gap exponent $\nu z\approx0.5$ in three dimensions and
+anisotropy between $0\leq\delta\leq1$, a result consistent with the dynamic
+exponent $z=1$ for the Gaussian character of the bond-operator treatment. At
+low but finite temperatures, in the antiferromagnetic phase, the line of Neel
+transitions is calculated for $\delta\ll1$ and $\delta\approx1$. For $d>2$ it
+is only re-normalized by the anisotropy parameter and varies with the distance
+to the quantum critical point QCP $|g|$ as, $T_N \propto |g|^{\psi}$ where the
+shift exponent $\psi=1/(d-1)$. Nevertheless, in two dimensions, long range
+magnetic order occurs only at T=0 for any $\delta$. In the paramagnetic phase,
+we find a power law temperature dependence on the specific heat at the
+\textit{quantum liquid trajectory} $J/t=(J/t)_{c}$, $T\to0$. It behaves as
+$C_{V}\propto T^{d}$ for $\delta\leq 1$ and $\delta\approx1$, in concordance
+with the scaling theory for $z=1$.",0801.2792v1
+2008-01-29,Searching for a Correlation Between Cosmic-Ray Sources Above 10^{19} eV and Large-Scale Structure,"We study the anisotropy signature which is expected if the sources of ultra
+high energy, >10^{19} eV, cosmic-rays (UHECRs) are extragalactic and trace the
+large scale distribution of luminous matter. Using the PSCz galaxy catalog as a
+tracer of the large scale structure (LSS), we derive the expected all sky
+angular distribution of the UHECR intensity. We define a statistic, that
+measures the correlation between the predicted and observed UHECR arrival
+direction distributions, and show that it is more sensitive to the expected
+anisotropy signature than the power spectrum and the two point correlation
+function. The distribution of the correlation statistic is not sensitive to the
+unknown redshift evolution of UHECR source density and to the unknown strength
+and structure of inter-galactic magnetic fields. We show, using this statistic,
+that recently published >5.7x10^{19} eV Auger data are inconsistent with
+isotropy at ~98% CL, and consistent with a source distribution that traces LSS,
+with some preference to a source distribution that is biased with respect to
+the galaxy distribution. The anisotropy signature should be detectable also at
+lower energy, >4x10^{19} eV. A few fold increase of the Auger exposure is
+likely to increase the significance to >99% CL, but not to >99.9% CL (unless
+the UHECR source density is comparable or larger than that of galaxies). In
+order to distinguish between different bias models, the systematic uncertainty
+in the absolute energy calibration of the experiments should be reduced to well
+below the current ~25%.",0801.4516v2
+2008-04-01,"A Cosmic Ray Positron Anisotropy due to Two Middle-Aged, Nearby Pulsars?","Geminga and B0656+14 are the closest pulsars with characteristic ages in the
+ran ge of 100 kyr to 1 Myr. They both have spindown powers of the order 3e34
+erg/s at present. The winds of these pulsars had most probably powered pulsar
+wind nebulae (PWNe) that broke up less than about 100 kyr after the birth of
+the pulsars. Assuming that leptonic particles accelerated by the pulsars were
+confined in th e PWNe and were released into the interstellar medium (ISM) on
+breakup of the PW Ne, we show that, depending on the pulsar parameters, both
+pulsars make a non-ne gligible contribution to the local cosmic ray (CR)
+positron spectrum, and they m ay be the main contributors above several GeV.
+The relatively small angular dist ance between Geminga and B0656+14 thus
+implies an anisotropy in the local CR po sitron flux at these energies. We
+calculate the contribution of these pulsars to the locally observed CR electr
+on and positron spectra depending on the pulsar birth period and the magnitude
+o f the local CR diffusion coefficient. We further give an estimate of the
+expecte d anisotropy in the local CR positron flux. Our calculations show that
+within the framework of our model, the local CR posit ron spectrum imposes
+constraints on pulsar parameters for Geminga and B0656+14, notably the pulsar
+period at birth, and also the local interstellar diffusion co efficient for CR
+leptons.",0804.0220v1
+2008-04-26,"Spatial Periodicity of Galaxy Number Counts, CMB Anisotropy, and SNIa Hubble Diagram Based on the Universe Accompanied by a Non-Minimally Coupled Scalar Field","We have succeeded in establishing a cosmological model with a non-minimally
+coupled scalar field $\phi$ that can account not only for the spatial
+periodicity or the {\it picket-fence structure} exhibited by the galaxy $N$-$z$
+relation of the 2dF survey but also for the spatial power spectrum of the
+cosmic microwave background radiation (CMB) temperature anisotropy observed by
+the WMAP satellite. The Hubble diagram of our model also compares well with the
+observation of Type Ia supernovae. The scalar field of our model universe
+starts from an extremely small value at around the nucleosynthesis epoch,
+remains in that state for sufficiently long periods, allowing sufficient time
+for the CMB temperature anisotropy to form, and then starts to grow in
+magnitude at the redshift $z$ of $\sim 1$, followed by a damping oscillation
+which is required to reproduce the observed picket-fence structure of the
+$N$-$z$ relation. To realize such behavior of the scalar field, we have found
+it necessary to introduce a new form of potential $V(\phi)\propto
+\phi^2\exp(-q\phi^2)$, with $q$ being a constant. Through this parameter $q$,
+we can control the epoch at which the scalar field starts growing.",0804.4240v1
+2008-05-28,Effect of anisotropy on the ground-state magnetic ordering of the spin-one quantum $J_{1}^{XXZ}$--$J_{2}^{XXZ}$ model on the square lattice,"We study the zero-temperature phase diagram of the
+$J_{1}^{XXZ}$--$J_{2}^{XXZ}$ Heisenberg model for spin-1 particles on an
+infinite square lattice interacting via nearest-neighbour ($J_1 \equiv 1$) and
+next-nearest-neighbour ($J_2 > 0$) bonds. Both bonds have the same $XXZ$-type
+anisotropy in spin space. The effects on the quasiclassical N\'{e}el-ordered
+and collinear stripe-ordered states of varying the anisotropy parameter
+$\Delta$ is investigated using the coupled cluster method carried out to high
+orders. By contrast with the spin-1/2 case studied previously, we predict no
+intermediate disordered phase between the N\'{e}el and collinear stripe phases,
+for any value of the frustration $J_2/J_1$, for either the $z$-aligned ($\Delta
+> 1$) or $xy$-planar-aligned ($0 \leq \Delta < 1$) states. The quantum phase
+transition is determined to be first-order for all values of $J_2/J_1$ and
+$\Delta$. The position of the phase boundary $J_{2}^{c}(\Delta)$ is determined
+accurately. It is observed to deviate most from its classical position $J_2^c =
+{1/2}$ (for all values of $\Delta > 0$) at the Heisenberg isotropic point
+($\Delta = 1$), where $J_{2}^{c}(1) = 0.55 \pm 0.01$. By contrast, at the XY
+isotropic point ($\Delta = 0$), we find $J_{2}^{c}(0) = 0.50 \pm 0.01$. In the
+Ising limit ($\Delta \to \infty$) $J_2^c \to 0.5$ as expected.",0805.4388v2
+2008-05-29,Pre-equilibrium dilepton production from an anisotropic quark-gluon plasma,"We calculate leading-order dilepton yields from a quark-gluon plasma which
+has a time-dependent anisotropy in momentum space. Such anisotropies can arise
+during the earliest stages of quark-gluon plasma evolution due to the rapid
+longitudinal expansion of the created matter. Two phenomenological models for
+the proper time dependence of the parton hard momentum scale, p_hard, and the
+plasma anisotropy parameter, xi, are constructed which describe the transition
+of the plasma from its initial non-equilibrium state to an isotropic
+thermalized state. The first model constructed interpolates between 1+1
+dimensional free streaming at early times and 1+1 dimensional ideal
+hydrodynamical expansion at late times. In the second model we include the
+effect of collisional broadening of the parton distribution functions in the
+early-time pre-equilibrium stage of plasma evolution. We find for both cases
+that for fixed initial conditions high-energy dilepton production is enhanced
+by pre-equilibrium emission. When the models are constrained to fixed final
+pion multiplicity the dependence of the resulting spectra on the assumed plasma
+isotropization time is reduced. Using our most realistic
+collisionally-broadened model we find that high-transverse momentum dilepton
+production would be enhanced by at most 40% at the Relativistic Heavy Ion
+Collider and 50% at CERN Large Hadron Collider if one assumes an
+isotropization/thermalization time of 2 fm/c. Given sufficiently precise
+experimental data this enhancement could be used to determine the plasma
+isotropization time experimentally.",0805.4552v2
+2008-06-10,Impact of Point Source Clustering on Cosmological Parameters with CMB Anisotropies,"The faint radio point sources that are unresolved in cosmic microwave
+background (CMB) anisotropy maps are likely to be a biased tracer of the
+large-scale structure dark matter distribution. While the shot-noise
+contribution to the angular power spectrum of unresolved radio point sources is
+included either when optimally constructing the CMB angular power spectrum, as
+with WMAP data, or when extracting cosmological parameters, we suggest that
+clustering part of the point source power spectrum should also be included.
+This is especially necessary at high frequencies above 150 GHz, where the
+clustering of far-IR sources is expected to dominate the shot-noise level of
+the angular power spectrum at tens of arcminute angular scales of both radio
+and sub-mm sources. We make an estimate of source clustering of unresolved
+radio sources in both WMAP and ACBAR, and marginalize over the amplitude of
+source clustering in each CMB data set when model fitting for cosmological
+parameters. For the combination of WMAP 5-year data and ACBAR, we find that the
+spectral index changes from the value of $0.963 \pm 0.014$ to $0.959 \pm 0.014$
+(at 68% c.l.) when the clustering power spectrum of point sources is included
+in model fits. While we find that the differences are marginal with and without
+source clustering in current data, it may be necessary to account for source
+clustering with future datasets such as Planck, especially to properly model
+fit anisotropies at arcminute angular scales. If clustering is not accounted
+and point sources are modeled with a shot-noise only out to $l \sim 2000$, the
+spectral index will be biased by about 1.5$\sigma$.",0806.1742v1
+2008-06-15,Magnetic interactions of cold atoms with anisotropic conductors,"We analyze atom-surface magnetic interactions on atom chips where the
+magnetic trapping potentials are produced by current carrying wires made of
+electrically anisotropic materials. We discuss a theory for time dependent
+fluctuations of the magnetic potential, arising from thermal noise originating
+from the surface. It is shown that using materials with a large electrical
+anisotropy results in a considerable reduction of heating and decoherence rates
+of ultra-cold atoms trapped near the surface, of up to several orders of
+magnitude. The trap loss rate due to spin flips is expected to be significantly
+reduced upon cooling the surface to low temperatures. In addition, the
+electrical anisotropy significantly suppresses the amplitude of static spatial
+potential corrugations due to current scattering within imperfect wires. Also
+the shape of the corrugation pattern depends on the electrical anisotropy: the
+preferred angle of the scattered current wave fronts can be varied over a wide
+range. Materials, fabrication, and experimental issues are discussed, and
+specific candidate materials are suggested.",0806.2427v2
+2008-06-15,Anisotropy in the electrical resistivity and susceptibility of superconducting BaFe$_{2}$As$_{2}$ single crystals,"Sizable single crystals of $BaFe_2As_2$ have been grown with self-flux
+method. The crystals are plate-like with c-axis perpendicular to the plane. The
+size can be as large as 3 x 5 x 0.2 $mm^3$. The resistivity anisotropy
+($\rho_c/\rho_{ab}$) is as large as about 150, and independent of temperature.
+The transport in ab plane and along c-axis direction shares the same scattering
+mechanism. In contrast to the magnetic behavior of polycrystalline samples, no
+Curie-Weiss behavior are observed, a temperature linear dependent
+susceptibility occurs above spin-density-wave (SDW) transition. The
+susceptibility behavior is very similar to that of antiferromagnetic SDW
+chromium. Magnetic behavior of single crystal definitely gives evidence for
+existence of local moment except for the contribution to susceptibility from
+itinerant electrons. A resistivity minimum strongly dependent on magnetic field
+is observed. A log(1/T) divergency, similar to that of the underdoped cuprates,
+happens at low temperature. Here we first present intrinsic transport and
+magnetic properties, and their anisotropy from high quality single crystal.",0806.2452v2
+2008-06-26,Different resistivity response to spin density wave and superconductivity at 20 K in $Ca_{1-x}Na_xFe_2As_2$,"We report that intrinsic transport and magnetic properties, and their
+anisotropy from high quality single crystal $CaFe_2As_2$. The resistivity
+anisotropy ($\rho_c/\rho_{ab}$) is $\sim 50 $, and less than 150 of
+$BaFe_2As_2$, which arises from the strong coupling along c-axis due to an
+apparent contraction of about 0.13 nm compared to $BaFe_2As_2$. Temperature
+independent anisotropy indicates that the transport in ab plane and along
+c-axis direction shares the same scattering mechanism. In sharp contrast to the
+case of parent compounds $ROFeAs$ (R=rare earth) and $MFe_2As_2$ (M=Ba and Sr),
+spin-density-wave (SDW) ordering (or structural transition) leads to a steep
+increase of resistivity in $CaFe_2As_2$. Such different resistivity response to
+SDW ordering is helpful to understand the role played by SDW ordering in
+Fe-based high-$T_c$ superconductors. The susceptibility behavior is very
+similar to that observed in single crystal $BaFe_2As_2$. A linear temperature
+dependent susceptibility occurs above SDW transition of about 165 K. Partial
+substitution of Na for Ca suppresses the SWD ordering (anomaly in resistivity)
+and induces occurrence of superconductivity at $\sim 20$ K.",0806.4279v1
+2008-08-14,Measurement of the dark matter velocity anisotropy in galaxy clusters,"The internal dynamics of a dark matter structure may have the remarkable
+property that the local temperature in the structure depends on direction. This
+is parametrized by the velocity anisotropy beta which must be zero for relaxed
+collisional structures, but has been shown to be non-zero in numerical
+simulations of dark matter structures. Here we present a method to infer the
+radial profile of the velocity anisotropy of the dark matter halo in a galaxy
+cluster from X-ray observables of the intracluster gas. This non-parametric
+method is based on a universal relation between the dark matter temperature and
+the gas temperature which is confirmed through numerical simulations. We apply
+this method to observational data and we find that beta is significantly
+different from zero at intermediate radii. Thus we find a strong indication
+that dark matter is effectively collisionless on the dynamical time-scale of
+clusters, which implies an upper limit on the self-interaction cross-section
+per unit mass sigma/m < 1 cm2/g. Our results may provide an independent way to
+determine the stellar mass density in the central regions of a relaxed cluster,
+as well as a test of whether a cluster is in fact relaxed.",0808.2049v1
+2008-09-05,Anomalous CMB north-south asymmetry,"Several accurate analyses have revealed a statistically significant
+North-South ecliptic asymmetry in the large-angle correlations strength of the
+Cosmic Microwave Background (CMB) radiation temperature field data from the
+Wilkinson Microwave Anisotropy Probe (WMAP). This asymmetry is inconsistent
+with the statistical isotropy expected in the concordance cosmological model
+LCDM. It has been suggested that a possible cause-effect relationship exists
+between this large-angle anisotropy and the anomalous CMB quadrupole-octopole
+planes alignment. In turn, this later phenomenon (or both) would be a
+consequence of one or more of the following undesired effects in CMB data: a
+systematic error in the data processing or in the instrument characterization,
+residual foregrounds, and large-angle correlations induced by the incomplete
+sky CMB data (cut-sky masks are needed to reject Galactic foregrounds). Here,
+it is proved that the North-South (NS) asymmetry is unrelated to the quadrupole
+(l=2) and the octopole (l=3) properties because we find, at high confidence
+levels, such large-angle anisotropy in three- and five-year WMAP CMB maps
+containing only the multipole components 4 <= l <= 10. The statistical
+significance depends on both, the CMB map analyzed as well as the cut-sky mask
+applied to exclude foregrounds. The significance level of the NS-asymmetry is
+less in five-year WMAP data with KQ75 (> 90% CL) than it is in three-year data
+with Kp0 (> 96% CL). Additionally, robustness tests show that the statistical
+significance of the NS-asymmetry is affected by the use of the KQ85 and KQ75
+masks in five-year single-frequency WMAP CMB maps, whereas it is insensitive
+with respect to application of the Kp2 and Kp0 masks in three-year
+single-frequency WMAP CMB maps.",0809.0934v1
+2008-09-10,Extremely Anisotropic Scintillations,"A small number of quasars exhibit interstellar scintillation on time-scales
+less than an hour; their scintillation patterns are all known to be
+anisotropic. Here we consider a totally anisotropic model in which the
+scintillation pattern is effectively one-dimensional. For the persistent rapid
+scintillators J1819+3845 and PKS1257-326 we show that this model offers a good
+description of the two-station time-delay measurements and the annual cycle in
+the scintillation time-scale. Generalising the model to finite anisotropy
+yields a better match to the data but the improvement is not significant and
+the two additional parameters which are required to describe this model are not
+justified by the existing data. The extreme anisotropy we infer for the
+scintillation patterns must be attributed to the scattering medium rather than
+a highly elongated source. For J1819+3845 the totally anisotropic model
+predicts that the particular radio flux variations seen between mid July and
+late August should repeat between late August and mid November, and then again
+between mid November and late December as the Earth twice changes its direction
+of motion across the scintillation pattern. If this effect can be observed then
+the minor-axis velocity component of the screen and the orientation of that
+axis can both be precisely determined. In reality the axis ratio is finite,
+albeit large, and spatial decorrelation of the flux pattern along the major
+axis may be observable via differences in the pairwise fluxes within this
+overlap region; in this case we can also constrain both the major-axis velocity
+component of the screen and the magnitude of the anisotropy.",0809.1694v1
+2008-09-18,Azimuthal anisotropy and fundamental symmetries in QCD matter at RHIC,"A study of collective behavior in heavy ion collisions provides one of the
+most sensitive and promising probes for investigation of possible formation of
+new extreme state of strong interacting matter and elucidating its properties.
+Systematic of experimental results for final state azimuthal anisotropy is
+presented for heavy ion interactions at RHIC. Experimental data for azimuthal
+anisotropy indicate that the final state strongly interacting matter under
+extreme conditions behaves as near-ideal liquid rather, than ideal gas of
+quarks and gluons. The strong quenching of jets and the dramatic modification
+of jet-like azimuthal correlations, observed in ${Au+Au}$ collisions, are
+evidences of the extreme energy loss of partons traversing matter which
+contains a large density of color charges. For the first time, dependence of
+the jet suppression on orientation of a jet with respect to the reaction plane
+is found at RHIC experimentally. The model of compound collective flow and
+corresponding analytic approach are discussed. The possible violations of
+$\cal{P}$ and $\cal{CP}$ symmetries of strong interactions in heavy ion
+collisions at different initial energies are considered. Thus, now the fact is
+established firmly, that extremely hot and dense matter created in relativistic
+heavy ion collisions at RHIC differs dramatically from everything that was
+observed and investigated before.",0809.3130v1
+2008-10-20,The CMBR ISW and HI 21-cm Cross-correlation Angular Power Spectrum,"The late-time growth of large scale structures (LSS) is imprinted in the CMBR
+anisotropy through the Integrated Sachs Wolfe (ISW) effect. This is perceived
+to be a very important observational probe of dark energy. Future observations
+of redshifted 21-cm radiation from the cosmological neutral hydrogen (HI)
+distribution hold the potential of probing the LSS over a large redshift range.
+We have investigated the possibility of detecting the ISW through
+cross-correlations between the CMBR anisotropies and redshifted 21-cm
+observations. Assuming that the HI traces the dark matter, we find that the
+ISW-HI cross-correlation angular power spectrum at an angular multipole l is
+proportional to the dark matter power spectrum evaluated at the comoving wave
+number l/r, where r is the comoving distance to the redshift from which the HI
+signal originated. The amplitude of the cross-correlation signal depends on
+parameters related to the HI distribution and the growth of cosmological
+perturbations. However the cross-correlation is extremely weak as compared to
+the CMBR anisotropies and the predicted HI signal. As a consequence the
+cross-correlation signal is smaller than the cosmic variance, and a
+statistically significant detection is not very likely.",0810.3649v2
+2008-10-23,Collective Phenomena in the Non-Equilibrium Quark-Gluon Plasma,"In this work we study the non-equilibrium dynamics of a quark-gluon plasma,
+as created in heavy-ion collisions. We investigate how big of a role plasma
+instabilities can play in the isotropization and equilibration of a quark-gluon
+plasma. In particular, we determine, among other things, how much collisions
+between the particles can reduce the growth rate of unstable modes. This is
+done both in a model calculation using the hard-loop approximation, as well as
+in a real-time lattice simulation combining both classical Yang-Mills-fields as
+well as inter-particle collisions. The new extended version of the simulation
+is also used to investigate jet transport in isotropic media, leading to a
+cutoff-independent result for the transport coefficient q-hat. The precise
+determination of such transport coefficients is essential, since they can
+provide important information about the medium created in heavy-ion collisions.
+In anisotropic media, the effect of instabilities on jet transport is studied,
+leading to a possible explanation for the experimental observation that
+high-energy jets traversing the plasma perpendicular to the beam axis
+experience much stronger broadening in rapidity than in azimuth. The
+investigation of collective modes in the hard-loop limit is extended to
+fermionic modes, which are shown to be all stable. Finally, we study the
+possibility of using high energy photon production as a tool to experimentally
+determine the anisotropy of the created system. Knowledge of the degree of
+local momentum-space anisotropy reached in a heavy-ion collision is essential
+for the study of instabilities and their role for isotropization and
+thermalization, because their growth rate depends strongly on the anisotropy",0810.4306v1
+2008-11-03,Compensation-dependent in-plane magnetization reversal processes in Ga1-xMnxP1-ySy,"We report the effect of dilute alloying of the anion sublattice with S on the
+in-plane uniaxial magnetic anisotropy and magnetization reversal process in
+Ga1-xMnxP as measured by both ferromagnetic resonance (FMR) and superconducting
+quantum interference device (SQUID) magnetometry. At T=5K, raising the S
+concentration increases the uniaxial magnetic anisotropy between in-plane <011>
+directions while decreasing the magnitude of the (negative) cubic anisotropy
+field. Simulation of the SQUID magnetometry indicates that the energy required
+for the nucleation and growth of domain walls decreases with increasing y.
+These combined effects have a marked influence on the shape of the
+field-dependent magnetization curves; while the direction remains the easy axis
+in the plane of the film, the field dependence of the magnetization develops
+double hysteresis loops in the [011] direction as the S concentration increases
+similar to those observed for perpendicular magnetization reversal in lightly
+doped Ga1-xMnxAs. The incidence of double hysteresis loops is explained with a
+simple model whereby magnetization reversal occurs by a combination of coherent
+spin rotation and noncoherent spin switching, which is consistent with both FMR
+and magnetometry experiments. The evolution of magnetic properties with S
+concentration is attributed to compensation of Mn acceptors by S donors, which
+results in a lowering of the concentration of holes that mediate
+ferromagnetism.",0811.0385v1
+2009-01-28,Spin canting in a Dy-based Single-Chain Magnet with dominant next-nearest neighbor antiferromagnetic interactions,"We investigate theoretically and experimentally the static magnetic
+properties of single crystals of the molecular-based Single-Chain Magnet (SCM)
+of formula [Dy(hfac)$_{3}$NIT(C$_{6}$H$_{4}$OPh)]$_{\infty}$ comprising
+alternating Dy$^{3+}$ and organic radicals. A peculiar inversion between maxima
+and minima in the angular dependence of the magnetic molar susceptibility
+$\chi_{M}$ occurs on increasing temperature. Using information regarding the
+monomeric building block as well as an {\it ab initio} estimation of the
+magnetic anisotropy of the Dy$^{3+}$ ion, this anisotropy-inversion phenomenon
+can be assigned to weak one-dimensional ferromagnetism along the chain axis.
+This indicates that antiferromagnetic next-nearest-neighbor interactions
+between Dy$^{3+}$ ions dominate, despite the large Dy-Dy separation, over the
+nearest-neighbor interactions between the radicals and the Dy$^{3+}$ ions.
+Measurements of the field dependence of the magnetization, both along and
+perpendicularly to the chain, and of the angular dependence of $\chi_{M}$ in a
+strong magnetic field confirm such an interpretation. Transfer matrix
+simulations of the experimental measurements are performed using a classical
+one-dimensional spin model with antiferromagnetic Heisenberg exchange
+interaction and non-collinear uniaxial single-ion anisotropies favoring a
+canted antiferromagnetic spin arrangement, with a net magnetic moment along the
+chain axis. The fine agreement obtained with experimental data provides
+estimates of the Hamiltonian parameters, essential for further study of the
+dynamics of rare-earths based molecular chains.",0901.4409v1
+2009-02-04,Spin dynamics of frustrated easy-axis triangular antiferromagnet 2H-AgNiO2 explored by inelastic neutron scattering,"We report inelastic neutron scattering measurements of the spin dynamics in
+the layered hexagonal magnet 2H-AgNiO2 which has stacked triangular layers of
+antiferromagnetically-coupled Ni2+ spins (S=1) ordered in a collinear
+alternating stripe pattern. We observe a broad band of magnetic excitations
+above a small gap of 1.8 meV and extending up to 7.5 meV, indicating strongly
+dispersive excitations. The measured dispersions of the boundaries of the
+powder-averaged spectrum can be quantitatively explained by a linear spin-wave
+dispersion for triangular layers with antiferromagnetic nearest- and weak
+next-nearest neighbor couplings, a strong easy-axis anisotropy and additional
+weak inter-layer couplings. The resulting dispersion relation has global minima
+not at magnetic Bragg wavevectors but at symmetry-related soft points and we
+attribute this anomalous feature to the strong competition between the
+easy-axis anisotropy and the frustrated antiferromagnetic couplings. We have
+also calculated the quantum corrections to the dispersion relation to order 1/S
+in spin-wave theory by extending the work of Chubukov and Jolicoeur [Phys. Rev.
+B v46, 11137 (1992)] and find that the presence of easy-axis anisotropy
+significantly reduces the quantum renormalizations predicted for the isotropic
+model.",0902.0676v1
+2009-02-04,Optical Anisotropy of Schwarzschild Metric within Equivalent Medium Framework,"It is has been long known that the curved space in the presence of
+gravitation can be described as a non-homogeneous anisotropic medium in flat
+geometry with different constitutive equations. In this article, we show that
+the eigenpolarizations of such medium can be exactly solved, leading to a
+pseudo-isotropic description of curved vacuum with two refractive index
+eigenvalues having opposite signs, which correspond to forward and backward
+travel in time. We conclude that for a rotating universe, time-reversal
+symmetry is broken. We also demonstrate the applicability of this method to
+Schwarzschild metric and derive exact forms of refractive index. We derive the
+subtle optical anisotropy of space around a spherically symmetric, non-rotating
+and uncharged blackhole in the form of an elegant closed form expression, and
+show that the refractive index in such a pseudo-isotropic system would be a
+function of coordinates as well as the direction of propagation. Corrections
+arising from such anisotropy in the bending of light are shown and a simplified
+system of equations for ray-tracing in the equivalent medium of Schwarzschild
+metric is found.",0902.0728v7
+2009-02-05,Anisotropic clustering of inertial particles in homogeneous shear flow,"Recently, clustering of inertial particles in turbulence has been thoroughly
+analyzed for statistically homogeneous isotropic flows. Phenomenologically,
+spatial homogeneity of particles configurations is broken by the advection of a
+range of eddies determined by the Stokes relaxation time of the particles which
+results in a multi-scale distribution of local concentrations and voids. Much
+less is known concerning anisotropic flows. Here, by addressing direct
+numerical simulations (DNS) of a statistically steady particle-laden
+homogeneous shear flow, we provide evidence that the mean shear preferentially
+orients particle patterns. By imprinting anisotropy on large scales velocity
+fluctuations, the shear indirectly affects the geometry of the clusters.
+Quantitative evaluation is provided by a purposely designed tool, the angular
+distribution function of particle pairs (ADF), which allows to address the
+anisotropy content of particles aggregates on a scale by scale basis. The data
+provide evidence that, depending on the Stokes relaxation time of the
+particles, anisotropic clustering may occur even in the range of scales where
+the carrier phase velocity field is already recovering isotropy. The strength
+of the singularity in the anisotropic component of the ADF quantifies the level
+of fine scale anisotropy, which may even reach values of more than 30%
+direction-dependent variation in the probability to find two close-by particles
+at viscous scale separation.",0902.0893v1
+2009-02-15,Sudden Critical Current Drops Induced in S/F Structures,"In the search for new physical properties of S/F structures, we have found
+that the superconductor critical current can be controlled by the domain state
+of the neighboring ferromagnet. The superconductor is a thin wire of thickness
+d_{s} ~ 2 xi_{S}. Nb/Co and Nb/Py (Permalloy Ni_{80}Fe_{20}) bilayer structures
+were grown with a significant magnetic anisotropy. Critical current
+measurements of Nb/Co structures with ferromagnet thickness d_{F} > 30nm show
+sudden drops in two very defined steps when the measurements are made along the
+hard axes direction (i.e. current track parallel to hard anisotropy axes
+direction). These drops disappear when they are made along the easy axis
+direction or when the ferromagnet thickness is below 30nm. The drops are
+accompanied by vortex flux flow. In addition magnetorestistance measurements
+close to Tc show a sharp increase near saturation fields of the ferromagnet.
+Similar results are reproduced in Nb/Py bilayer structure with the ferromagnet
+thickness d_{F} ~ 50nm along the easy anisotropy axes. These results are
+explained as being due to spontaneous vortex formation and flow induced by
+Bloch domain walls of the ferromagnet underneath. We argue these Bloch domain
+walls produce a 2D vortex-antivortex lattice structure.",0902.2572v2
+2009-03-13,2D XY Behavior observed in quasi-2D quantum Heisenberg antiferromagnets,"The magnetic properties of a new family of molecular-based quasi-two
+dimension $S=1/2$ Heisenberg antiferromagnets are reported. Three compounds,
+($Cu(pz)_2(ClO_4)_2$, $Cu(pz)_2(BF_4)_2$, and $[Cu(pz)_2(NO_3)](PF_6)$) contain
+similar planes of Cu$^{2+}$ ions linked into magnetically square lattices by
+bridging pyrazine molecules (pz = $C_4H_4N_2$). The anions provide charge
+balance as well as isolation between the layers. Single crystal measurements of
+susceptibility and magnetization, as well as muon spin relaxation studies,
+reveal low ratios of N\'{e}el temperatures to exchange strengths ($4.25 / 17.5
+= 0.243$, $3.80/15.3=0.248$, and $3.05/10.8=0.282$, respectively) while the
+ratio of the anisotropy fields $H_A$ (kOe) to the saturation field
+$H_\mathrm{SAT}$ (kOe) are small ($2.6/490 = 5.3\times10^{-3}$,
+$2.4/430=5.5\times10^{-3}$, and $0.07/300=2.3\times10^{-4}$, respectively),
+demonstrating close approximations to a 2D Heisenberg model. The
+susceptibilities of ClO$_4$ and BF$_4$ show evidence of an exchange anisotropy
+crossover (Heisenberg to $XY$) at low temperatures; their ordering transitions
+are primarily driven by the $XY$ behavior with the ultimate 3D transition
+appearing parasitically. The PF$_6$ compound remains Heisenberg-like at all
+temperatures, with its transition to the N\'{e}el state due to the interlayer
+interactions. Effects of field-induced anisotropy have been observed.",0903.2470v1
+2009-03-18,Approximate Analytic Spectra of Reionized CMB Anisotropies and Polarization generated by Relic Gravitational Waves,"We present an approximate, analytical calculation of the reionized spectra
+$C_l^{XX}$ of cosmic microwave background radiation (CMB) anisotropies and
+polarizations generated by relic gravitational waves (RGWs). Three simple
+models of reionization are explored, whose visibility functions are fitted by
+gaussian type of functions as approximations. We have derived the analytical
+polarization $\beta_l$ and temperature anisotropies $\alpha_l$, both consisting
+of two terms proportional to RGWs at the decoupling and at the reionization as
+well. The explicit dependence of $\beta_l$ and $\alpha_l$ upon the reionization
+time $\eta_r$, the duration $\Delta\eta_r$, and the optical depth $\kappa_r$
+are demonstrated. Moreover, $\beta_l$ and $\alpha_l$ contain $\kappa_r$ in
+different coefficients, and the polarization spectra $C_l^{EE}$ are $C_l^{BB}$
+are more sensitive probes of reionization than $C_l^{TT}$. These results
+facilitate examination of the reionization effects, in particular, the
+degeneracies of $\kappa_r$ with the normalization amplitude and with the
+initial spectral index of RGWs. It is also found that reionization also causes
+a $\kappa_r$-dependent shift $\Delta l\sim 20$ of the zero multipole $l_0$ of
+$C_l^{TE}$, an effect that should be included in order to detect the traces of
+RGWs. Compared with numerical results, the analytical $C_l^{XX}$ as
+approximation have the limitation. For the primary peaks in the range $l\simeq
+(30, 600)$, the error is $\le 3%$ in three models. In the range $l < 20$ for
+the reionization bumps, the error is $\le 15%$ for $C_l^{EE}$ and $C_l^{BB}$ in
+the two extended reionization models, and $C_l^{TT}$ and $C_l^{TE}$ have much
+larger departures for $l<10$. The bumps in the sudden reionization model are
+too low.",0903.3159v2
+2009-04-08,Anisotropy of the upper critical field in a Co-doped BaFe2As2 single crystal,"The temperature dependence of the upper critical magnetic field (Hc2) in a
+BaFe1.84Co0.16As2 single crystal was determined via resistivity, for the
+inter-plane (H^ab) and in-plane (H//ab) directions in pulsed and static
+magnetic fields of up to 60 T. Suppressing superconductivity in a pulsed
+magnetic field at 3He temperatures permits us to construct an H-T phase diagram
+from quantitative Hc2(0) values and determine its behavior in low temperatures.
+Hc2(0) with H//ab (Hc2//(0)) and H^ab (Hc2^(0)) are ~ 55 T and 50 T
+respectively. These values are ~ 1.2 - 1.4 times larger than the weak-coupling
+Pauli paramagnetic limit (Hp = 1.84 Tc), indicating that enhanced paramagnetic
+limiting is essential and this superconductor is unconventional. While Hc2//ab
+is saturated at low temperature, Hc2 with H^ab (Hc2^) exhibits almost linear
+temperature dependence towards T = 0 K which results in reduced anisotropy of
+Hc2 in low temperature. The anisotropy of Hc2 was ~ 3.4 near Tc, and decreases
+rapidly with lower temperatures reaching ~ 1.1 at T = 0.7 K.",0904.1418v3
+2009-04-16,Significant foreground unrelated non-acoustic anisotropy on the one degree scale in WMAP 5-year observations,"The spectral variation of the cosmic microwave background (CMB) as observed
+by WMAP was tested using foreground reduced WMAP5 data, by producing
+subtraction maps at the 1$^\circ$ angular resolution between the two
+cosmological bands of V and W, for masked sky areas that avoid the Galactic
+disk. The resulting $V-W$ map revealed a non-acoustic signal over and above the
+WMAP5 pixel noise, with two main properties. Firstly, it possesses quadrupole
+power at the $\approx$ 1 $\mu K$ level which may be attributed to foreground
+residuals. Second, it fluctuates also at all values of $\ell >$ 2, especially
+on the $1^\circ$ scale ($200 \lesssim \ell \lesssim 300$). The behavior is {\it
+random and symmetrical} about zero temperature with a r.m.s. amplitude of
+$\approx$ 7 $\mu K$, or 10 % of the maximum CMB anisotropy, which would require
+a `cosmic conspiracy' among the foreground components if it is a consequence of
+their existences. Both anomalies must be properly diagnosed and corrected if
+`precision cosmology' is the claim. The second anomaly is, however, more
+interesting because it opens the question on whether the CMB anisotropy
+genuinely represents primordial density seeds.",0904.2513v3
+2009-05-15,The contribution of the kinematic Sunyaev-Zel'dovich Effect from the Warm Hot Intergalactic Medium to the Five-Year WMAP Data,"We study the contribution of the kinematic Sunyaev-Zel'dovich (kSZ) effect,
+generated by the warm-hot intergalactic medium (WHIM), to the cosmic microwave
+background (CMB) temperature anisotropies in the Five-Year Wilkinson Microwave
+Anisotropy Probe (WMAP) data. We explore the concordance LambdaCDM cosmological
+model, with and without this kSZ contribution, using a Markov chain Monte Carlo
+algorithm. Our model requires a single extra parameter to describe this new
+component. Our results show that the inclusion of the kSZ signal improves the
+fit to the data without significantly altering the best-fit cosmological
+parameters except Obh^2. The improvement is localized at the l>500 multipoles.
+For the best-fit model, this extra component peaks at l~450 with an amplitude
+of 129 muK^2, and represents 3.1% of the total power measured by the Wilkinson
+Microwave Anisotropy Probe. Nevertheless, at the 2-sigma level a null kSZ
+contribution is still compatible with the data. Part of the detected signal
+could arise from unmasked point sources and/or Poissonianly distributed
+foreground residuals. A statistically more significant detection requires the
+wider frequency coverage and angular resolution of the forthcoming Planck
+mission.",0905.2582v2
+2009-05-27,A Three-Point Cosmic Ray Anisotropy Method,"The two-point angular correlation function is a traditional method used to
+search for deviations from expectations of isotropy. In this paper we develop
+and explore a statistically descriptive three-point method with the intended
+application being the search for deviations from isotropy in the highest energy
+cosmic rays. We compare the sensitivity of a two-point method and a
+""shape-strength"" method for a variety of Monte-Carlo simulated anisotropic
+signals. Studies are done with anisotropic source signals diluted by an
+isotropic background. Type I and II errors for rejecting the hypothesis of
+isotropic cosmic ray arrival directions are evaluated for four different event
+sample sizes: 27, 40, 60 and 80 events, consistent with near term data
+expectations from the Pierre Auger Observatory. In all cases the ability to
+reject the isotropic hypothesis improves with event size and with the fraction
+of anisotropic signal. While ~40 event data sets should be sufficient for
+reliable identification of anisotropy in cases of rather extreme (highly
+anisotropic) data, much larger data sets are suggested for reliable
+identification of more subtle anisotropies. The shape-strength method
+consistently performs better than the two point method and can be easily
+adapted to an arbitrary experimental exposure on the celestial sphere.",0905.4488v2
+2009-06-13,Angular momentum transfer and the size - mass relation in early - type galaxies,"Early - type galaxies (ETGs) define a narrow strip in the size - mass plane
+because of the observed correlation between the effective radius $R_{eff}$ and
+the total stellar mass $M_{\star}$. When expressed in logarithmic units, a
+linear relation, $\log{R_{eff}} \propto \gamma \log{M_{\star}}$, is indeed
+observationally found, but the slope $\gamma$ deviates from the canonical
+$\gamma = 1/2$ value which can be naively predicted for a spherically symmetric
+isotropic system. We propose here that a transfer of angular momentum to the
+stellar component induces an anisotropy in the velocity space thus leading to a
+modified distribution function (DF). Assuming an Osipkov - Merritt like
+anisotropic DF, we derive an analytic relation between the slope $\gamma$ of
+the size - mass relation and the slope $\alpha$ of the angular momentum term in
+the DF. With this simple model, we are then able to recover the observed
+$\gamma$ value provided $\alpha$ is suitably set. It turns out that an
+anisotropy profile which is tangential inside $\sim 0.6 r_a$ and radial
+outside, with $r_a$ the anisotropy radius, is able to reproduce the observed
+size - mass relation observed for massive ($M_{\star} \ge 2 \times 10^{10} \
+h^{-1} {\rm M}_{\odot}$) elliptical galaxies.",0906.2457v1
+2009-06-24,Anisotropic Fermi liquid theory of the ultra cold fermionic polar molecules: Landau parameters and collective modes,"We study the Fermi liquid properties of the cold atomic dipolar Fermi gases
+with the explicit dipolar anisotropy using perturbative approaches. Due to the
+explicit dipolar anisotropy, Fermi surfaces exhibit distortions of the
+$d_{r^2-3z^2}$-type in three dimensions and of the $d_{x^2-y^2}$-type in two
+dimensions. The fermion self-energy, effective mass, and Fermi velocity develop
+the same anisotropy at the Hartree-Fock level proportional to the interaction
+strength. The Landau interaction parameters in the isotropic Fermi liquids
+become the tri-diagonal Landau interaction matrices in the dipolar Fermi
+liquids which renormalize thermodynamic susceptibilities. With large dipolar
+interaction strength, the Fermi surface collapses along directions
+perpendicular to the dipole orientation. The dynamic collective zero sound
+modes exhibit an anisotropic dispersion with the largest sound velocity
+propagating along the polar directions. Similarly, the longitudinal p-wave
+channel spin mode becomes a propagating mode with an anisotropic dispersion in
+multi-component dipolar systems.",0906.4403v5
+2009-06-29,J/psi azimuthal anisotropy relative to the reaction plane in Pb-Pb collisions at 158 GeV per nucleon,"The J/$\psi$ azimuthal distribution relative to the reaction plane has been
+measured by the NA50 experiment in Pb-Pb collisions at 158 GeV/nucleon. Various
+physical mechanisms related to charmonium dissociation in the medium created in
+the heavy ion collision are expected to introduce an anisotropy in the
+azimuthal distribution of the observed J/$\psi$ mesons at SPS energies. Hence,
+the measurement of J/$\psi$ elliptic anisotropy, quantified by the Fourier
+coefficient v$_2$ of the J/$\psi$ azimuthal distribution relative to the
+reaction plane, is an important tool to constrain theoretical models aimed at
+explaining the anomalous J/$\psi$ suppression observed in Pb-Pb collisions. We
+present the measured J/$\psi$ yields in different bins of azimuthal angle
+relative to the reaction plane, as well as the resulting values of the Fourier
+coefficient v$_{2}$ as a function of the collision centrality and of the
+J/$\psi$ transverse momentum. The reaction plane has been estimated from the
+azimuthal distribution of the neutral transverse energy detected in an
+electromagnetic calorimeter. The analysis has been performed on a data sample
+of about 100 000 events, distributed in five centrality or p$_{\rm T}$
+sub-samples. The extracted v$_{2}$ values are significantly larger than zero
+for non-central collisions and are seen to increase with p$_{\rm T}$.",0906.5376v2
+2009-07-15,Transport properties and the anisotropy of Ba_{1-x}K_xFe_2As_2 single crystals in normal and superconducting states,"The transport and superconducting properties of Ba_{1-x}K_xFe_2As_2 single
+crystals with T_c = 31 K were studied. Both in-plane and out-of plane
+resistivity was measured by modified Montgomery method. The in-plane
+resistivity for all studied samples, obtained in the course of the same
+synthesis, is almost the same, unlike to the out-of plane resistivity, which
+differ considerably. We have found that the resistivity anisotropy
+\gamma=\rho_c /\rho_{ab} is almost temperature independent and lies in the
+range 10-30 for different samples. This, probably, indicates on the extrinsic
+nature of high out-of-plane resistivity, which may appear due to the presence
+of the flat defects along Fe-As layers in the samples. This statement is
+supported by comparatively small effective mass anisotropy, obtained from the
+upper critical field measurements, and from the observation of the so-called
+""Friedel transition"", which indicates on the existence of some disorder in the
+samples in c-direction.",0907.2598v1
+2009-08-30,On the anisotropy barrier reduction in fast relaxing Mn12 single-molecule magnets,"A novel angle-swept high-frequency EPR (HFEPR) technique is described that
+enables in-situ alignment of single-crystal samples containing low-symmetry
+magnetic species such as single-molecule magnets (SMMs). This cavity-based
+method involves recording spectra at fixed frequency and field, while sweeping
+the field orientation. The method is applied to the study of a low-symmetry
+Jahn-Teller variant of the spin S = 10 Mn12 SMMs (e.g. Mn12-acetate). The
+low-symmetry complex is also an SMM, but with a significantly reduced barrier
+to magnetization reversal (Ueff ~ 43 K) and, hence, faster relaxation at low
+temperature in comparison with the high-symmetry species. Mn12 complexes that
+crystallize in lower symmetry structures exhibit a tendency for one or more of
+the Mn(III) Jahn-Teller axes to be abnormally oriented, which is believed to be
+the cause of the faster relaxation. An extensive HFEPR study of
+[Mn12O12(O2CCH2But)16(H2O)4].CH2Cl2.MeNO2 is presented in order to examine the
+influence of the abnormally oriented Jahn-Teller axis on the effective barrier.
+The reduction in the axial anisotropy, D, is found to be insufficient to
+account for the nearly 40% reduction in Ueff. However, the reduced symmetry of
+the Mn12 core gives rise to a very significant 2nd order transverse anisotropy,
+E ~ D/6. This, in turn, causes a significant mixing of spin projection states
+well below the top of the classical barrier. Thus, magnetic quantum tunneling
+is the dominant factor contributing to the barrier reduction in fast relaxing
+Mn12 SMMs.",0908.4434v1
+2009-09-24,Assembly bias and the dynamical structure of dark matter halos,"Based on the Millennium Simulation we examine assembly bias for the halo
+properties: shape, triaxiality, concentration, spin, shape of the velocity
+ellipsoid and velocity anisotropy. For consistency we determine all these
+properties using the same set of particles, namely all gravitationally
+self-bound particles belonging to the most massive sub-structure of a given
+friends-of-friends halo. We confirm that near-spherical and high-spin halos
+show enhanced clustering. The opposite is true for strongly aspherical and
+low-spin halos. Further, below the typical collapse mass, M*, more concentrated
+halos show stronger clustering whereas less concentrated halos are less
+clustered which is reversed for masses above M*. Going beyond earlier work we
+show that: (1) oblate halos are more strongly clustered than prolate ones; (2)
+the dependence of clustering on the shape of the velocity ellipsoid coincides
+with that of the real-space shape, although the signal is stronger; (3) halos
+with weak velocity anisotropy are more clustered, whereas radially anisotropic
+halos are more weakly clustered; (4) for all highly clustered subsets we find
+systematically less radially biased velocity anisotropy profiles. These
+findings indicate that the velocity structure of halos is tightly correlated
+with environment.",0909.4302v2
+2009-10-09,Quasi-Chemical and Structural Analysis of Polarizable Anion Hydration,"Quasi-chemical theory is utilized to analyze the roles of solute polarization
+and size in determining the structure and thermodynamics of bulk anion
+hydration for the Hofmeister series Cl$^-$, Br$^-$, and I$^-$. Excellent
+agreement with experiment is obtained for whole salt hydration free energies
+using the polarizable AMOEBA force field. The quasi-chemical approach exactly
+partitions the solvation free energy into inner-shell, outer-shell packing, and
+outer-shell long-ranged contributions by means of a hard-sphere condition.
+Small conditioning radii, even well inside the first maximum of the
+ion-water(oxygen) radial distribution function, result in Gaussian behavior for
+the long-ranged contribution that dominates the ion hydration free energy. The
+spatial partitioning allows for a mean-field treatment of the long-ranged
+contribution, leading to a natural division into first-order electrostatic,
+induction, and van der Waals terms. The induction piece exhibits the strongest
+ion polarizability dependence, while the larger-magnitude first-order
+electrostatic piece yields an opposing but weaker polarizability dependence. In
+addition, a structural analysis is performed to examine the solvation
+anisotropy around the anions. As opposed to the hydration free energies, the
+solvation anisotropy depends more on ion polarizability than on ion size:
+increased polarizability leads to increased anisotropy. The water dipole
+moments near the ion are similar in magnitude to bulk water, while the ion
+dipole moments are found to be significantly larger than those observed in
+quantum mechanical studies. Possible impacts of the observed over-polarization
+of the ions on simulated anion surface segregation are discussed.",0910.1786v2
+2009-10-19,Fermi surface topology and magneto-quantum oscillations for under-doped YBCO with hopping anisotropy,"We investigate a chiral d-density wave (CDDW) mean field Hamiltonian in
+momentum space, which also includes the in-plane hopping anisotropy parameter
+e, for the under-doped YBCO to explore the possibility of quantum oscillations
+(QO) in the specific heat in the presence of a changing magnetic field (B). The
+inclusion is motivated by the experimental signature of nematic order found in
+cuprates in neutron scattering experiments of Hinkov et al. (see Ref.[10]). We
+obtain the Fermi surface topologies, without and with magnetic field
+background, including the elastic scattering by impurities in the investigation
+within t-matrix approximation framework. The topologies are found to be
+distinct from the Fermi arc picture: we find that the minimally gapped portion
+of Fermi surface forms closed loops (hole pockets) and not arcs. However, some
+k-points of the electron pockets are found to be associated with the negative
+density of state values (see Ref.[28]) when B and e are zero; for non-zero B
+and e slightly positive these pockets acquire positive DOS values. The latter
+thus seems to justify the inclusion of the hopping anisotropy in the
+Hamiltonian. We relate these findings to QO in specific heat. We show that the
+origin of the main frequency of the oscillations is the electron pocket of the
+Fermi surface at a magnetic field B equal to 50 T.",0910.3464v1
+2009-11-02,"Kinematics of Milky Way Satellites: Mass Estimates, Rotation Limits, and Proper Motions","In the past several years high resolution kinematic data sets from Milky Way
+satellite galaxies have confirmed earlier indications that these systems are
+dark matter dominated objects. Further understanding of what these galaxies
+reveal about cosmology and the small scale structure of dark matter relies in
+large part on a more detailed interpretation of their internal kinematics. This
+article discusses a likelihood formalism that extracts important quantities
+from the kinematic data, including the amplitude of rotation, proper motion,
+and the mass distribution. In the simplest model the projected error on the
+rotational amplitude is shown to be $\sim 0.5 $ km s$^{-1}$ with $\sim 10^3$
+stars from either classical or ultra-faint satellites. The galaxy Sculptor is
+analyzed for the presence of a rotational signal; no significant detection of
+rotation is found, and given this result limits are derived on the Sculptor
+proper motion. A criteria for model selection is discussed that determines the
+parameters required to describe the dark matter halo density profiles and the
+stellar velocity anisotropy. Applied to four data sets with a wide range of
+velocities, the likelihood is found to be more sensitive to variations in the
+slope of the dark matter density profile than variations in the velocity
+anisotropy. Models with variable radial velocity anisotropy are shown to be
+preferred relative to those in which this quantity is constant at all radii in
+the galaxy.",0911.0220v1
+2009-11-06,Cosmological hydrogen recombination: The effect of extremely high-n states,"Calculations of cosmological hydrogen recombination are vital for the
+extraction of cosmological parameters from cosmic microwave background (CMB)
+observations, and for imposing constraints to inflation and re-ionization. The
+Planck} mission and future experiments will make high precision measurements of
+CMB anisotropies at angular scales as small as l~2500, necessitating a
+calculation of recombination with fractional accuracy of ~10^{-3}. Recent work
+on recombination includes two-photon transitions from high excitation states
+and many radiative transfer effects. Modern recombination calculations
+separately follow angular momentum sublevels of the hydrogen atom to accurately
+treat non-equilibrium effects at late times (z<900). The inclusion of extremely
+high-n (n>100) states of hydrogen is then computationally challenging,
+preventing until now a determination of the maximum n needed to predict CMB
+anisotropy spectra with sufficient accuracy for Planck. Here, results from a
+new multi-level-atom code (RecSparse) are presented. For the first time,
+`forbidden' quadrupole transitions of hydrogen are included, but shown to be
+negligible. RecSparse is designed to quickly calculate recombination histories
+including extremely high-n states in hydrogen. Histories for a sequence of
+values as high as n_max=250 are computed, keeping track of all angular momentum
+sublevels and energy shells of the hydrogen atom separately. Use of an
+insufficiently high n_max value (e.g., n_max=64) leads to errors (e.g., 1.8
+sigma for Planck) in the predicted CMB power spectrum. Extrapolating errors,
+the resulting CMB anisotropy spectra are converged to 0.5 sigma at
+Fisher-matrix level for n_max=128, in the purely radiative case.",0911.1359v2
+2009-11-23,Magnetic anisotropy determination and magnetic hyperthermia properties of small Fe nanoparticles in the superparamagnetic regime,"We report on the magnetic and hyperthermia properties of iron nanoparticles
+synthesized by organometallic chemistry. They are 5.5 nm in diameter and
+display a saturation magnetization close to the bulk one. Magnetic properties
+are dominated by the contribution of aggregates of nanoparticles with respect
+to individual isolated nanoparticles. Alternative susceptibility measurements
+are been performed on a low interacting system obtained after eliminating the
+aggregates by centrifugation. A quantitative analysis using the Gittleman s
+model allow a determination of the effective anisotropy Keff = 1.3 * 10^5
+J.m^{-3}, more than two times the magnetocristalline value of bulk iron.
+Hyperthermia measurements are performed on agglomerates of nanoparticles at a
+magnetic field up to 66 mT and at frequencies in the range 5-300 kHz. Maximum
+measured SAR is 280 W/g at 300 kHz and 66 mT. Specific absorption rate (SAR)
+displays a square dependence with the magnetic field below 30 mT but deviates
+from this power law at higher value. SAR is linear with the applied frequency
+for mu_0H=19 mT. The deviations from the linear response theory are discussed.
+A refined estimation of the optimal size of iron nanoparticles for hyperthermia
+applications is provided using the determined effective anisotropy value.",0911.4413v1
+2009-11-25,A Scaling Relation of the Evolving Tidal Fields in a LCDM Cosmology,"We report the finding of a scaling relation among the cosmic-web anisotropy
+parameter $A$, the linear density rms fluctuation sigma(r) and the linear
+growth factor D(z). Using the tidal field derived from the Millennium
+Simulation on 512^{3} grids at z=0, 2, 5 and 127, we calculate the largest
+eigenvalues $\lambda$ of the local tidal tensor at each grid resolution and
+measure its distance-averaged two-point correlation function, xi_{lambda}, as a
+function of the cosines of polar angles cos(theta) in the local principal axis
+frame. We show that xi_{lambda} is quite anisotropic, increasing toward the
+directions of minimal matter compression, and that the anisotropy of
+xi_{lambda} increases as the redshift, z, decreases and as the upper distance
+cutoff r_{c} decreases. Fitting the numerical results to an analytic fitting
+model \xi_{\lambda}(\cos\theta)\propto (1+A\cos^{n}\theta)^{-1}, it is found
+that the best fit value of A, dubbed the cosmic-web anisotropy parameter,
+varies systematically with sigma(r_{c}) and D(z), allowing us to determine the
+simple empiral scaling relation A(r_{c},z)=0.8, D^{0.76}(z), sigma (r_{c})$.",0911.4755v2
+2010-02-10,Power and spectral index anisotropy of the entire inertial range of turbulence in the fast solar wind,"We measure the power and spectral index anisotropy of high speed solar wind
+turbulence from scales larger than the outer scale down to the ion gyroscale,
+thus covering the entire inertial range. We show that the power and spectral
+indices at the outer scale of turbulence are approximately isotropic. The
+turbulent cascade causes the power anisotropy at smaller scales manifested by
+anisotropic scalings of the spectrum: close to k^{-5/3} across and k^{-2} along
+the local magnetic field, consistent with a critically balanced Alfvenic
+turbulence. By using data at different radial distances from the Sun, we show
+that the width of the inertial range does not change with heliocentric distance
+and explain this by calculating the radial dependence of the ratio of the outer
+scale to the ion gyroscale. At the smallest scales of the inertial range, close
+to the ion gyroscale, we find an enhancement of power parallel to the magnetic
+field direction coincident with a decrease in the perpendicular power. This is
+most likely related to energy injection by ion kinetic modes such as the
+firehose instability and also marks the beginning of the dissipation range of
+solar wind turbulence.",1002.2096v1
+2010-03-13,"A thermally stable heating mechanism for the intracluster medium: turbulence, magnetic fields and plasma instabilities","We consider the problem of self-regulated heating and cooling in galaxy
+clusters and the implications for cluster magnetic fields and turbulence.
+Viscous heating of a weakly collisional magnetised plasma is regulated by the
+pressure anisotropy with respect to the local direction of the magnetic field.
+The intracluster medium is a high-beta plasma, where pressure anisotropies
+caused by the turbulent stresses and the consequent local changes in the
+magnetic field will trigger very fast microscale instabilities. We argue that
+the net effect of these instabilities will be to pin the pressure anisotropies
+at a marginal level, controlled by the plasma beta parameter. This gives rise
+to local heating rates that turn out to be comparable to the radiative cooling
+rates. Furthermore, we show that a balance between this heating and
+Bremsstrahlung cooling is thermally stable, unlike the often conjectured
+balance between cooling and thermal conduction. Given a sufficient (and
+probably self-regulating) supply of turbulent power, this provides a physical
+mechanism for mitigating cooling flows and preventing cluster core collapse.
+For observed density and temperature profiles, the assumed balance of viscous
+heating and radiative cooling allows us to predict magnetic-field strengths,
+turbulent velocities and turbulence scales as functions of distance from the
+centre. Specific predictions and comparisons with observations are given for
+several different clusters. Our predictions can be further tested by future
+observations of cluster magnetic fields and turbulent velocities.",1003.2719v2
+2010-03-16,Mass modification of itinerant carriers in RKKY oscillations induced by finite range exchange interactions,"We investigate the Ruderman-Kittel-Kasuya-Yosida oscillations of the
+itinerant carrier spin density in a system where those oscillations appear only
+due to a finite distribution of a localized spin. The system represents a
+half-infinite one-dimensional quantum wire with a magnetic impurity located at
+its edge. In contrast to the conventional model of a point-like exchange
+interaction the itinerant carrier spin density oscillations in this system
+exist. We {\it analytically} demonstrate that when the radius of the exchange
+interaction is less than the wave length of the itinerant carriers living on
+the Fermi surface, the long range behavior of the oscillations is identical to
+the one taking place in the zero radius limit of the same exchange interaction
+but for an infinite one-dimensional quantum wire where, in comparison with the
+original half-infinite system, the mass of the itinerant carriers is {\it
+strongly} modified by the exchange interaction radius. On the basis of our
+analysis we make a suggestion on directionality of surface
+Ruderman-Kittel-Kasuya-Yosida interaction shown in recent experiments: we
+believe that in general the anisotropy of the Ruderman-Kittel-Kasuya-Yosida
+interaction could result not only from the anisotropy of the {\it Fermi
+surface} of itinerant carriers but also from the anisotropy of the {\it spin
+carrying atomic orbitals} of magnetic impurities.",1003.3140v2
+2010-03-22,Complexity and anisotropy in host morphology make populations safer against epidemic outbreaks,"One of the challenges in epidemiology is to account for the complex
+morphological structure of hosts such as plant roots, crop fields, farms,
+cells, animal habitats and social networks, when the transmission of infection
+occurs between contiguous hosts. Morphological complexity brings an inherent
+heterogeneity in populations and affects the dynamics of pathogen spread in
+such systems. We have analysed the influence of realistically complex host
+morphology on the threshold for invasion and epidemic outbreak in an SIR
+(susceptible-infected-recovered) epidemiological model. We show that disorder
+expressed in the host morphology and anisotropy reduces the probability of
+epidemic outbreak and thus makes the system more resistant to epidemic
+outbreaks. We obtain general analytical estimates for minimally safe bounds for
+an invasion threshold and then illustrate their validity by considering an
+example of host data for branching hosts (salamander retinal ganglion cells).
+Several spatial arrangements of hosts with different degrees of heterogeneity
+have been considered in order to analyse separately the role of shape
+complexity and anisotropy in the host population. The estimates for invasion
+threshold are linked to morphological characteristics of the hosts that can be
+used for determining the threshold for invasion in practical applications.",1003.4239v1
+2010-03-29,Effective field theory for Sp(N) antiferromagnets and its phase structure,"In this paper, we study quantum Sp(N) antiferromagnetic (AF) Heisenberg
+models in two dimensions (2D) by using the Schwinger-boson representation and
+the path-integral methods. An effective field theory, which is an extension of
+CP^{N-1} model in (2+1)D, is derived and its phase structure is studied by the
+1/N-expansion. We introduce a spatial anisotropy in the exchange couplings and
+show that the effective coupling constant in the CP^{N-1} model is an
+increasing function of the anisotropy. For the SU(N) AF Heisenberg model, which
+is a specific case of the Sp(N) model, we found that phase transition from the
+ordered ""N\'eel state"" to paramagnetic phase takes place as the anisotropy is
+increased. In the vicinity of the SU(N) symmetric point, this phase structure
+is retained. However as a parameter that controls explicit breaking of the
+SU(N) symmetry is increased, a new phase, which is similar to the spiral-spin
+phase with a nematic order in frustrated SU(2) spin systems, appears. It is
+shown that at that phase transition point, a local SU(2) gauge symmetry with
+composite SU(2) gauge field appears in the low-energy sector. It is another
+example of symmetry-enhancement phenomenon at low energies. We also introduce a
+lattice gauge-theoretical model, which is a counterpart of the effective field
+theory, and study its phase structure by means of the Monte-Carlo simulations.",1003.5412v1
+2010-04-12,Anisotropic Anomalous Diffusion assessed in the human brain by scalar invariant indices,"A new method to investigate anomalous diffusion in human brain is proposed.
+The method has been inspired by both the stretched-exponential model proposed
+by Hall and Barrick (HB) and DTI. Quantities extracted using HB method were
+able to discriminate different cerebral tissues on the basis of their
+complexity, expressed by the stretching exponent gamma and of the anisotropy of
+gamma across different directions. Nevertheless, these quantities were not
+defined as scalar invariants like mean diffusivity and fractional anisotropy,
+which are eigenvalues of the diffusion tensor. We hypotesize instead that the
+signal may be espressed as a simple stretched-exponential only along the
+principal axes of diffusion, while in a generic direction the signal is modeled
+as a combination of three different stretched-exponentials. In this way, we
+derived indices to quantify both the tissue anomalous diffusion and its
+anisotropy, independently of the reference frame of the experiment. We tested
+and compare our new method with DTI and HB approaches applying them to 10
+healty subjects brain at 3T. Our experimental results show that our parameters
+are highly correlated to intrinsic local geometry when compared to HB indices.
+Moreover, they offer a different kind of contrast when compared to DTI outputs.
+Specifically, our indices show a higher capability to discriminate among
+different areas of the corpus callosum, which are known to be associated to
+different axonal densities.",1004.2001v1
+2010-04-29,Non-gaussianity and Statistical Anisotropy in Cosmological Inflationary Models,"We study the statistical descriptors for some cosmological inflationary
+models that allow us to get large levels of non-gaussianity and violations of
+statistical isotropy. Basically, we study two different class of models: a
+model that include only scalar field perturbations, specifically a subclass of
+small-field slow-roll models of inflation with canonical kinetic terms, and
+models that admit both vector and scalar field perturbations. We study the
+former to show that it is possible to attain very high, including observable,
+values for the levels of non-gaussianity f_{NL} and \tao_{NL} in the bispectrum
+B_\zeta and trispectrum T_\zeta of the primordial curvature perturbation \zeta
+respectively. Such a result is obtained by taking care of loop corrections in
+the spectrum P_\zeta, the bispectrum B_\zeta and the trispectrum T_\zeta .
+Sizeable values for f_{NL} and \tao_{NL} arise even if \zeta is generated
+during inflation. For the latter we study the spectrum P_\zeta, bispectrum
+B_\zeta and trispectrum $T_\zeta of the primordial curvature perturbation when
+\zeta is generated by scalar and vector field perturbations. The tree-level and
+one-loop contributions from vector field perturbations are worked out
+considering the possibility that the one-loop contributions may be dominant
+over the tree level terms. The levels of non-gaussianity f_{NL} and \tao_{NL},
+are calculated and related to the level of statistical anisotropy in the power
+spectrum, g_\zeta . For very small amounts of statistical anisotropy in the
+power spectrum, the levels of non-gaussianity may be very high, in some cases
+exceeding the current observational limit.",1004.5363v1
+2010-05-20,A new test for the Galactic formation and evolution -- prediction for the orbital eccentricity distribution of the halo stars,"We present theoretical calculations for the differential distribution of
+stellar orbital eccentricity in a galaxy halo, assuming that the stars
+constitute a spherical, collisionless system in dynamical equilibrium with a
+dark matter halo. In order to define the eccentricity e of a halo star for
+given energy E and angular momentum L, we adopt two types of gravitational
+potential, such as an isochrone potential and a Navarro-Frenk-White potential,
+that could form two ends covering in-between any realistic potential of dark
+matter halo. Based on a distribution function of the form f(E,L) that allows
+constant anisotropy in velocity dispersions characterized by a parameter \beta,
+we find that the eccentricity distribution is a monotonically increasing
+function of e for the case of highly radially anisotropic velocity dispersions
+(\beta > 0.6), while showing a hump-like shape for the cases from radial
+through tangential velocity anisotropy (\beta < 0.6). We also find that when
+the velocity anisotropy agrees with that observed for the Milky Way halo stars
+(\beta = 0.5-0.7), a nearly linear eccentricity distribution of N(e) \alpha e
+results at e < 0.7, largely independent of the potential adopted. Our
+theoretical eccentricity distribution would be a vital tool of examining how
+far out in the halo the dynamical equilibrium has been achieved, through
+comparison with kinematics of halo stars sampled at greater distances. Given
+that large surveys of the SEGUE and Gaia projects would be in progress, we
+discuss how our results would serve as a new guide in exploring the formation
+and evolution of the Milky Way halo.",1005.3685v1
+2010-05-28,Limits on light-speed anisotropies from Compton scattering of high-energy electrons,"The possibility of anisotropies in the speed of light relative to the
+limiting speed of electrons is considered. The absence of sidereal variations
+in the energy of Compton-edge photons at the ESRF's GRAAL facility constrains
+such anisotropies representing the first non-threshold collision-kinematics
+study of Lorentz violation. When interpreted within the minimal Standard-Model
+Extension, this result yields the two-sided limit of 1.6 x 10^{-14} at 95%
+confidence level on a combination of the parity-violating photon and electron
+coefficients kappa_{o+} and c. This new constraint provides an improvement over
+previous bounds by one order of magnitude.",1005.5230v2
+2010-06-22,Loop algorithm for classical Heisenberg models with spin-ice type degeneracy,"In many frustrated Ising models, a single-spin flip dynamics is frozen out at
+low temperatures compared to the dominant interaction energy scale because of
+the discrete ""multiple valley"" structure of degenerate ground-state manifold.
+This makes it difficult to study low-temperature physics of these frustrated
+systems by using Monte Carlo simulation with the standard single-spin flip
+algorithm. A typical example is the so-called spin ice model, frustrated
+ferromagnets on the pyrochlore lattice. The difficulty can be avoided by a
+global-flip algorithm, the loop algorithm, that enables to sample over the
+entire discrete manifold and to investigate low-temperature properties. We
+extend the loop algorithm to Heisenberg spin systems with strong easy-axis
+anisotropy in which the ground-state manifold is continuous but still retains
+the spin-ice type degeneracy. We examine different ways of loop flips and
+compare their efficiency. The extended loop algorithm is applied to the
+following two models, a Heisenberg antiferromagnet with easy-axis anisotropy
+along the z axis, and a Heisenberg spin ice model with the local <111>
+easy-axis anisotropy. For both models, we demonstrate high efficiency of our
+loop algorithm by revealing the low-temperature properties which were hard to
+access by the standard single-spin flip algorithm. For the former model, we
+examine the possibility of order-from-disorder and critically check its
+absence. For the latter model, we elucidate a gas-liquid-solid transition,
+namely, crossover or phase transition among paramagnet, spin-ice liquid, and
+ferromagnetically-ordered ice-rule state.",1006.4300v2
+2010-06-30,Broadband Fizeau Interferometers for Astrophysics,"Measurements of the 2.7 K cosmic microwave background (CMB) radiation now
+provide the most stringent constraints on cosmological models. The power
+spectra of the temperature anisotropies and the $E$-mode polarization of the
+CMB are explained well by the inflationary paradigm. The next generation of CMB
+experiments aim at providing the most direct evidence for inflation through the
+detection of $B$-modes in the CMB polarization, presumed to have been caused by
+gravitational waves generated during the inflationary epoch around $10^{-34}$s.
+The $B$-mode polarization signals are very small ($\leq$10$^{-8}$K) compared
+with the temperature anisotropies ($\sim 10^{-4}$K). Systematic effects in CMB
+telescopes can cause leakage from temperature anisotropy into polarization.
+Bolometric interferometry (BI) is a novel approach to measuring this small
+signal with lower leakage. If BI can be made to work over wide bandwidth
+($\sim20-30\%$) it can provide similar sensitivity to imagers. Subdividing the
+frequency passband of a Fizeau interferometer would mitigate the problem of
+`fringe smearing.' Furthermore, the approach should allow simultaneous
+measurements in image space and visibility space. For subdividing the frequency
+passsband (`sub-band splitting' henceforth), we write an expression for the
+output from every baseline at every detector in the focal plane as a sum of
+visibilities in different frequency sub-bands. For operating the interferometer
+simultaneously as an imager, we write the output as two integrals over the sky
+and the focal plane, with all the phase differences accounted for.}{The
+sub-band splitting method described here is general and can be applied to
+broad-band Fizeau interferometers across the electromagnetic spectrum.
+Applications to CMB measurements and to long-baseline optical interferometry
+are promising.",1006.5936v1
+2010-07-23,Nonspherical similarity solutions for dark halo formation,"We carry out fully 3-dimensional simulations of evolution from self-similar,
+spherically symmetric linear perturbations of a Cold Dark Matter dominated
+Einstein-de Sitter universe. As a result of the radial orbit instability, the
+haloes which grow from such initial conditions are triaxial with major-to-minor
+axis ratios of order 3:1. They nevertheless grow approximately self-similarly
+in time. In all cases they have power-law density profiles and near-constant
+velocity anisotropy in their inner regions. Both the power-law index and the
+value of the velocity anisotropy depend on the similarity index of the initial
+conditions, the former as expected from simple scaling arguments. Halo
+structure is thus not ""universal"" but remembers the initial conditions. On
+larger scales the density and anisotropy profiles show two characteristic
+scales, corresponding to particles at first pericentre and at first apocentre
+after infall. They are well approximated by the NFW model only for one value of
+the similarity index. In contrast, at all radii within the outer caustic the
+pseudo phase-space density can be fit by a single power law with an index which
+depends only very weakly on the similarity index of the initial conditions.
+This behaviour is very similar to that found for haloes formed from LCDM
+initial conditions and so can be considered approximately universal.",1007.4195v1
+2010-07-28,Small anisotropy of the lower critical field and $s_\pm$-wave two-gap feature in single crystal LiFeAs,"The in- and out-of-plane lower critical fields and magnetic penetration
+depths for LiFeAs were examined. The anisotropy ratio $\gamma_{H_{c1}}(0)$ is
+smaller than the expected theoretical value, and increased slightly with
+increasing temperature from 0.6$T_c$ to $T_c$. This small degree of anisotropy
+was numerically confirmed by considering electron correlation effect. The
+temperature dependence of the penetration depths followed a power
+law($\sim$$T^n$) below 0.3$T_c$, with $n$$>$3.5 for both $\lambda_{ab}$ and
+$\lambda_c$. Based on theoretical studies of iron-based superconductors, these
+results suggest that the superconductivity of LiFeAs can be represented by an
+extended $s_\pm$-wave due to weak impurity scattering effect. And the
+magnitudes of the two gaps were also evaluted by fitting the superfluid density
+for both the in- and out-of-plane to the two-gap model. The estimated values
+for the two gaps are consistent with the results of angle resolved
+photoemission spectroscopy and specific heat experiments.",1007.4906v2
+2010-08-03,CMB observations in LTB universes: Part II: the kSZ effect in an LTB universe,"We study the kinematic Sunyaev-Zel'dovich (kSZ) effect in a
+Lem\^itre-Tolman-Bondi (LTB) universe model whose distance-redshift relation
+agrees with that of the concordance $\Lambda$CDM model at redshifts
+$z\lesssim2$. This LTB universe model has a void with size comparable to the
+Hubble horizon scale. We first determine the decoupling epoch in this LTB
+universe model by an approximate analytical condition under a few simplified
+assumptions on the physical quantities at that epoch. Then we calculate the
+cosmic microwave background (CMB) anisotropy observed in the rest frame of
+clusters of galaxies which are assumed to be at rest in the spatial comoving
+coordinates of the LTB universe model. We find that the obtained temperature
+anisotropies are dominated by dipole, although there may exist higher
+multi-poles in general. We may interpret this dipole anisotropy as the drift
+velocity of a cluster of galaxies relative to the CMB rest frame. Hence it
+gives rise to the kSZ effect. We calculate this effect and compare it with
+observational data. We find that if we assume the conventional adiabatic
+perturbation scenario at the time of decoupling, the drift velocity of clusters
+of galaxies becomes unacceptably large. Conversely, this observational
+constraint may be relaxed by introducing a non-adiabatic (i.e., primordially
+isocurvature) component of inhomogeneities at the time of decoupling. However,
+our result indicates that the necessary isocurvature perturbation amplitude is
+very large.",1008.0469v2
+2010-08-17,On the interactions of transverse ion-cyclotron waves with ions in solar wind plasma,"We show the evidence of ion-cyclotron dissipation mechanism in solar wind
+plasma using Helios data. From our statistical analysis we found that the wave
+power of high-frequency transverse waves (having frequencies between 0.01 and 1
+normalized to the proton gyrofrequency in the plasma frame) correlates with
+both, the proton temperature anisotropy, $T_{\perp}/T_{\parallel}$, and the
+normalized differential speed, $V_{\alpha p}/V_A$, between alpha particles and
+protons. Furthermore, when this speed stays below 0.5, then the alpha-particle
+temperature anisotropy correlate positively with the relative power of the
+transverse waves. However, if $V_{\alpha p}/V_A$ is larger than 0.6, then the
+alpha-particle temperature anisotropy tends to decrease towards values below
+unity, despite the presence of transverse waves with relatively large
+amplitudes. For small relative wave amplitude, it is found that alpha particles
+can even be heated more strongly than protons when the alpha-to-electron
+density ratio nearly or below 0.01. Our findings are in good agreement with
+predictions of kinetic theory for the resonant interaction of ions with
+Alfv\'en-cyclotron waves and for the resulting wave dissipation. Also, the
+study suggests that the turbulence could lead to the generation of parallel
+Alfven cyclotron waves.",1008.2893v3
+2010-11-10,Large scale anisotropies on halo infall,"We perform a statistical analysis of the peculiar velocity field around dark
+matter haloes in numerical simulations. We examine different properties of the
+infall of material onto haloes and its relation to central halo shapes and the
+shape of the large scale surrounding regions (LSSR). We find that the amplitude
+of the infall velocity field along the halo shape minor axis is larger than
+that along the major axis. This is consistent for general triaxial haloes, and
+for both prolate and oblate systems. We also report a strong anisotropy of the
+velocity field along the principal axes of the LSSR. The infall velocity field
+around dark matter haloes reaches a maximum value along the direction of the
+minor axis of the LSSR, whereas along the direction of its major axis, it
+exhibits the smallest velocities. We also analyse the dependence of the matter
+velocity field on the local environment. The amplitude of the infall velocity
+at high local density regions is larger than at low local density regions. The
+velocity field tends to be more laminar along the direction towards the minor
+axis of the LSSR, where the mean ratio between flow velocity and velocity
+dispersion is of order unity and nearly constant up to scales of 15 Mpc/h. We
+also detect anisotropies in the outflowing component of the velocity field,
+showing a maximum amplitude along the surrounding LSSR major axis.",1011.2494v1
+2010-11-16,Nematic spin fluid in the tetragonal phase of BaFe2As2,"Magnetic interactions are generally believed to play a key role in mediating
+electron pairing for superconductivity in iron arsenides; yet their character
+is only partially understood. Experimentally, the antiferromagnetic (AF)
+transition is always preceded by or coincident with a tetragonal to
+orthorhombic structural distortion. Although it has been suggested that this
+lattice distortion is driven by an electronic nematic phase, where a
+spontaneously generated electronic liquid crystal state breaks the C4
+rotational symmetry of the paramagnetic state, experimental evidence for
+electronic anisotropy has been either in the low-temperature orthorhombic phase
+or the tetragonal phase under uniaxial pressure that breaks this symmetry. Here
+we use inelastic neutron scattering to demonstrate the presence of a large
+in-plane spin anisotropy above TN in the unstressed tetragonal phase of
+BaFe2As2. In the low-temperature orthorhombic phase, we find highly anisotropic
+spin waves with a large damping along the AF a-axis direction. On warming the
+system to the paramagnetic tetragonal phase, the low-energy spin waves evolve
+into quasi-elastic excitations, while the anisotropic spin excitations near the
+zone boundary persist. These results strongly suggest that the spin nematicity
+we find in the tetragonal phase of BaFe2As2 is the source of the electronic and
+orbital anisotropy observed above TN by other probes, and has profound
+consequences for the physics of these materials.",1011.3771v1
+2010-11-22,Microwave Emission from the Edgeworth-Kuiper Belt and the Asteroid Belt Constrained from WMAP,"Objects in the Edgeworth-Kuiper belt and the main asteroid belt should emit
+microwaves that may give rise to extra anisotropy signals in the multipole of
+the cosmic microwave background (CMB) experiment. Constraints are derived from
+the absence of positive detection of such anisotropies for ell < 50, giving the
+total mass of Edgeworth-Kuiper belt objects to be smaller than 0.2 earth mass.
+This limit is consistent with the mass extrapolated from the observable
+population with the size of a > 15 km, assuming that the small-object
+population follows the power law in size dN/da ~ a^{-q} with the canonical
+index expected for collisional equilibrium, q ~ 3.5, with which 23% of the mass
+is ascribed to objects smaller than are observationally accessible down to
+grains. A similar argument applied to the main asteroid belt indicates that the
+grain population should not increase faster than q ~ 3.6 towards smaller radii,
+if it follows the power law continued to observed asteroids with larger radii.
+It is underlined that both cases are at or only slightly above the limit that
+can be physically significant, implying the importance of tightening further
+the CMB anisotropy limit, which may be attained with the observation at higher
+radio frequencies.",1011.4796v2
+2010-11-30,"Haldane, Large-D and Intermediate-D States in an S=2 Quantum Spin Chain with On-Site and XXZ Anisotropies","Using mainly numerical methods, we investigate the ground-state phase diagram
+of the S=2 quantum spin chain described by $H = \sum_j (S_j^x S_{j+1}^x + S_j^y
+S_{j+1}^y + \Delta S_j^z S_{j+1}^z) + D \sum_j (S_j^z)^2$, where $\Delta$
+denotes the $XXZ$ anisotropy parameter of the nearest-neighbor interactions and
+$D$ the on-site anisotropy parameter. We restrict ourselves to the case with
+$\Delta \ge 0$ and $D \ge 0$ for simplicity. Each of the phase boundary lines
+is determined by the level spectroscopy or the phenomenological renormalization
+analysis of numerical results of exact-diagonalization calculations. The
+resulting phase diagram on the $\Delta$-$D$ plane consists of four phases; the
+XY 1 phase, the Haldane/large-$D$ phase, the intermediate-$D$ phase and the
+N\'eel phase. The remarkable natures of the phase diagram are: (1) the Haldane
+state and the large-$D$ state belong to the same phase; (2) there exists the
+intermediate-$D$ phase which was predicted by Oshikawa in 1992; (3) the shape
+of the phase diagram on the $\Delta$-$D$ plane is different from that believed
+so far. We note that this is the first report of the observation of the
+intermediate-$D$ phase.",1011.6568v2
+2010-11-30,Effects of anisotropic winds on massive stars evolution,"Whenever stars are rotating very fast (Omega/Omega_crit > 0.7, with
+Omega_crit the Keplerian angular velocity of the star accounting for its
+deformation) radiative stellar winds are enhanced in polar regions. This
+theoretical prediction is now confirmed by interferometric observations of fast
+rotating stars.} Polar winds remove less angular momentum than spherical winds
+and thus allow the star to keep more angular momentum. We quantitatively assess
+the importance of this effect.
+  First we use a semi-analytical approach to estimate the variation of the
+angular momentum loss when the rotation parameter increases. Then we compute
+complete 9 MSun stellar models at very high angular velocities (starting on the
+ZAMS with Omega/Omega_crit = 0.8 and reaching the critical velocity during the
+Main Sequence) with and without radiative wind anisotropies.
+  When wind anisotropies are accounted for, the angular momentum loss rate is
+reduced by less than 4% for Omega/Omega_crit < 0.9 with respect to the case of
+spherical winds. The reduction amounts to at most 30% when the star is rotating
+near the critical velocity. These values result from two counteracting effects:
+on the one hand polar winds reduce the loss of angular momentum, on the other
+hand, surface deformations imply that the mass which is lost at high
+co-latitude is lost at a larger distance from the rotational axis and thus
+removes more angular momentum.
+  In contrast with previous studies, which neglected surface deformations, we
+show that the radiative wind anisotropies have a relatively modest effect on
+the evolution of the angular momentum content of fast rotating stars.",1011.6581v2
+2010-12-23,Turbulence in collisionless plasmas: statistical analysis from numerical simulations with pressure anisotropy,"In the past years we have experienced an increasing interest in understanding
+of the physical properties of collisionless plasmas, mostly because of the
+large number of astrophysical environments, e.g. the intracluster medium (ICM),
+containing magnetic fields which are strong enough to be coupled with the
+ionized gas and characterized by densities sufficiently low to prevent the
+pressure isotropization with respect to the magnetic line direction. Under
+these conditions a new class of kinetic instabilities arises, such as firehose
+and mirror ones, which were extensively studied in the literature. Their role
+in the turbulence evolution and cascade process in the presence of pressure
+anisotropy, however, is still unclear. In this work we present the first
+statistical analysis of turbulence in collisionless plasmas using three
+dimensional double isothermal magnetohydrodynamical with the
+Chew-Goldberger-Low closure (CGL-MHD) numerical simulations. We study models
+with different initial conditions to account for the firehose and mirror
+instabilities and to obtain different turbulent regimes. We study the
+probability distribution functions, spectra, structure functions and anisotropy
+of density and velocity fluctuations. The results indicate that in some cases
+the instabilities significantly modifies the statistical properties of
+turbulence and even though preliminary and restricted to very specific
+conditions, show that the physical properties of turbulence in collisionless
+plasmas, as those found in the ICM, may be very different from what has been
+largely believed. Implications can range from interchange of energies to cosmic
+rays acceleration.",1012.5125v1
+2011-01-31,Nuclear modification factor in an anisotropic {\em Quark-Gluon-Plasma},"We calculate the nuclear modification factor ($R_{AA}$) of light hadrons by
+taking into account the initial state momentum anisotropy of the quark gluon
+plasma (QGP) expected to be formed in relativistic heavy ion collisions. Such
+an anisotropy can result from the initial rapid longitudinal expansion of the
+matter. A phenomenological model for the space time evolution of the
+anisotropic QGP is used to obtain the time dependence of the anisotropy
+parameter $\xi$ and the hard momentum scale, $p_{\rm hard}$. The result is then
+compared with the PHENIX experimental data to constrain the isotropization time
+scale, $\tau_{\rm iso}$ for fixed initial conditions (FIC). It is shown that
+the extracted value of $\tau_{\rm iso}$ lies in the range $0.5 \leq \tau_{\rm
+iso} \leq 1.5$. However, using fixed final multiplicity (FFM) condition does
+not lead to any firm conclusion about the extraction of the isotropization
+time. The present calculation is also extended to contrast with the recent
+measurement of nuclear modification factor by ALICE collaboration at
+$\sqrt{s}=2.76$ TeV. It is argued that in the present approach, the extraction
+of $\tau_{\rm iso}$ at this energy is uncertain and, therfore, refinement of
+the model is necessary. The sensitivity of the results on the initial
+conditions has been discussed. We also present the nuclear modification factor
+at LHC energies with $\sqrt{s} = 5.5$ TeV.",1101.5855v2
+2011-03-15,Nernst effect in the cuprate superconductor YBCO: Broken rotational and translational symmetries,"The Nernst coefficient of the cuprate superconductor YBa2Cu3Oy was recently
+shown to become strongly anisotropic within the basal plane when cooled below
+the pseudogap temperature T*, revealing that the pseudogap phase breaks the
+four-fold rotational symmetry of the CuO2 planes. Here we report on the
+evolution of this Nernst anisotropy at low temperature, once superconductivity
+is suppressed by a magnetic field. We find that the anisotropy drops rapidly
+below 80 K, to vanish in the T=0 limit. We show that this loss of anisotropy is
+due to the emergence of a small high-mobility electron-like pocket in the Fermi
+surface at low temperature, a reconstruction attributed to a low-temperature
+state that breaks the translational symmetry of the CuO2 planes. We discuss the
+sequence of broken symmetries - first rotational, then translational - in terms
+of an electronic nematic-to-smectic transition such as could arise when
+unidirectional spin or charge modulations order. We compare YBa2Cu3Oy with
+iron-pnictide superconductors where the process of (unidirectional)
+antiferromagnetic ordering gives rises to the same sequence of broken
+symmetries.",1103.3044v1
+2011-04-19,The Primordial Curvature Perturbation from Vector Fields of General non-Abelian Groups,"We consider the generation of primordial curvature perturbation by general
+non-Abelian vector fields without committing to a particular group.
+Self-interactions of non-Abelian fields make the field perturbation
+non-Gaussian. We calculate the bispectrum of the field perturbation using the
+in-in formalism at tree level. The bispectrum is dominated by the classical
+evolution of fields outside the horizon. In view of this we show that the
+dominant contribution can be obtained from the homogeneous classical equation
+of motion. Then we calculate the power spectrum of the curvature perturbation.
+The anisotropy in spectrum is suppressed by the number of fields. This makes it
+possible for vector fields to be responsible for the total curvature
+perturbation in the Universe without violating observational bounds on
+statistical anisotropy. The bispectrum of the curvature perturbation is also
+anisotropic. Finally we give an example of the end-of-inflation scenario in
+which the curvature perturbation is generated by vector gauge fields through
+varying gauge coupling constant(s), which in covariant derivatives couples the
+Higgs field to the vector fields. We find that reasonably large gauge groups
+may result in the observable anisotropy in the power spectrum of the curvature
+perturbation.",1104.3629v2
+2011-04-28,Anisotropy in the Interaction of Ultracold Dysprosium,"The nature of the interaction between ultracold atoms with a large orbital
+and spin angular momentum has attracted considerable attention. It was
+suggested that such interactions can lead to the realization of exotic states
+of highly correlated matter. Here, we report on a theoretical study of the
+competing anisotropic dispersion, magnetic dipole-dipole, and electric
+quadrupole-quadrupole forces between two dysprosium atoms. Each dysprosium atom
+has an orbital angular momentum L=6 and magnetic moment $\mu=10\mu_B$. We show
+that the dispersion coefficients of the ground state adiabatic potentials lie
+between 1865 a.u. and 1890 a.u., creating a non-negligible anisotropy with a
+spread of 25 a.u. and that the electric quadrupole-quadrupole interaction is
+weak compared to the other interactions. We also find that for interatomic
+separations $R< 50\,a_0$ both the anisotropic dispersion and magnetic
+dipole-dipole potential are larger than the atomic Zeeman splittings for
+external magnetic fields of order 10 G to 100 G. At these separations spin
+exchange can occur. We finish by describing two scattering models for inelastic
+spin exchange. A universal scattering theory is used to model loss due to the
+anisotropy in the dispersion and a distorted-wave-Born theory is used to model
+losses from the magnetic dipole-dipole interaction for the $^{164}$Dy isotope.
+These models find loss rates that are the same order of magnitude as the
+experimental value.",1104.5411v1
+2011-07-18,Quasi-static magnetohydrodynamic turbulence at high Reynolds number,"We analyse the anisotropy of homogeneous turbulence in an electrically
+conducting fluid submitted to a uniform magnetic field, for low magnetic
+Reynolds number, in the quasi- static approximation. We interpret disagreeing
+previous predictions between linearized theory and simulations: in the linear
+limit, the kinetic energy of transverse velocity components, normal to the
+magnetic field, decays faster than the kinetic energy of the axial component,
+along the magnetic field (Moffatt (1967)); whereas many numerical studies
+predict a final state characterised by dominant energy of transverse velocity
+components. We investigate the corresponding nonlinear phenomenon using Direct
+Numerical Simulations of freely-decaying turbulence, and a two-point
+statistical spectral closure based on the Eddy Damped Quasi-Normal Markovian
+model. The transition from the three-dimensional turbulent flow to a
+""two-and-a-half-dimensional"" flow (Montgomery & Turner (1982)) is a result of
+the combined effects of short-time linear Joule dissipation and longer time
+nonlinear creation of polarisation anisotropy. It is this combination of linear
+and nonlinear effects which explains the disagreement between predictions from
+linearized theory and results from numerical simulations. The transition is
+characterized by the elongation of turbulent structures along the applied
+magnetic field, and by the strong anisotropy of directional two-point
+correlation spectra, in agreement with experimental evidence. Inertial
+equatorial transfers in both DNS and the model are presented to describe in
+detail the most important equilibrium dynamics. Spectral scalings are
+maintained in high Reynolds number turbulence attainable only with the EDQNM
+model, which also provides simplified modelling of the asymptotic state of
+quasi-static MHD turbulence.",1107.3435v1
+2011-08-25,3D simulations of gyrosynchrotron emission from mildly anisotropic nonuniform electron distributions in symmetric magnetic loops,"Microwave emission of solar flares is formed primarily by incoherent
+gyrosynchrotron radiation generated by accelerated electrons in coronal
+magnetic loops. The resulting emission depends on many factors, including
+pitch-angle distribution of the emitting electrons and the source geometry. In
+this work, we perform systematic simulations of solar microwave emission using
+recently developed tools (GS Simulator and fast gyrosynchrotron codes) capable
+of simulating maps of radio brightness and polarization as well as spatially
+resolved emission spectra. A 3D model of a symmetric dipole magnetic loop is
+used. We compare the emission from isotropic and anisotropic (of loss-cone
+type) electron distributions. We also investigate effects caused by
+inhomogeneous distribution of the emitting particles along the loop. It is
+found that effect of the adopted moderate electron anisotropy is the most
+pronounced near the footpoints and it also depends strongly on the loop
+orientation. Concentration of the emitting particles at the loop top results in
+a corresponding spatial shift of the radio brightness peak, thus reducing
+effects of the anisotropy. The high-frequency (around 50 GHz) emission spectral
+index is specified mainly by the energy spectrum of the emitting electrons;
+however, at intermediate frequencies (around 10-20 GHz), the spectrum shape is
+strongly dependent on the electron anisotropy, spatial distribution, and
+magnetic field nonuniformity. The implications of the obtained results for the
+diagnostics of the energetic electrons in solar flares are discussed.",1108.5150v1
+2011-09-30,Power Anisotropy in the Magnetic Field Power Spectral Tensor of Solar Wind Turbulence,"We observe the anisotropy of the power spectral tensor of magnetic field
+fluctuations in the fast solar wind for the first time. In heliocentric RTN
+coordinates the power in each element of the tensor has a unique dependence on
+the angle between the magnetic field and velocity of the solar wind (\theta)
+and the angle of the vector in the plane perpendicular to the velocity (\phi).
+We derive the geometrical effect of the high speed flow of the solar wind past
+the spacecraft on the power spectrum in the frame of the plasma P(k) to arrive
+at the observed power spectrum P(f,\theta,\phi) based on a scalar field
+description of turbulence theory. This allows us to predict the variation in
+the \phi direction and compare it to the data. We then transform the
+observations from RTN coordinates to magnetic-field-aligned coordinates. The
+observed reduced power spectral tensor matches the theoretical predictions we
+derive in both RTN and field-aligned coordinates which means that the local
+magnetic field we calculate with wavelet envelope functions is an accurate
+representation of the physical axis of symmetry for the turbulence and implies
+that on average the turbulence is axi-symmetric. We also show that we can
+separate the dominant toroidal component of the turbulence from the smaller but
+significant poloidal component and that these have different power anisotropy.
+We also conclude that the magnetic helicity is anisotropic and mostly
+two-dimensional, arising from wavevectors largely confined to the plane
+perpendicular to B.",1109.6877v2
+2011-10-14,Collective Flow Measurements from the PHENIX Experiment,"Recent collective flow measurements including higher moment event anisotropy
+from the PHENIX experiment are presented, and the particle type, beam energy
+dependence and the relation with jet modification are discussed. The measured
+higher order event anisotropy with event plane defined at forward rapidities
+and the long range correlation with large $\eta$ gaps are both consistent with
+initial geometrical fluctuation of the participating nuclei. In 200 GeV Au+Au
+collisions, higher order event anisotropy, especially simultaneous description
+of v$_2$ and v$_3$, is found to give an additional constraining power on
+initial geometrical condition and viscosity in the hydrodynamic calculations.
+v$_2$, v$_3$ and v$_4$ are almost unchanged down to the lower colliding energy
+at 39 GeV in Au+Au. The measured two particle correlation with subtraction of
+the measured v$_n$ parameters shows a significant effect on the shape and yield
+in the associate particle $\Delta\phi$ distribution with respect to the
+azimuthal direction of trigger particles. However some medium responses from
+jet suppression or jet modification seems to be observed. Direct photon v$_2$
+has been measured in 200 GeV Au+Au collisions. The measured v$_2$ is found to
+be small at high p$_{\rm T}$ as expected from non-suppressed direct photon
+R$_{\rm AA}$ $\simeq$ 1, which can be understood as being dominated by prompt
+photons from initial hard scattering. On the other hand, at lower p$_{\rm T}$
+$<$ 4 GeV/c it is found to be significantly larger than zero, which is
+comparable to other hadron v$_2$, where thermal photons are observed.",1110.3223v1
+2011-12-29,Anisotropy in the electronic structure of V2GeC investigated by soft x-ray emission spectroscopy and first-principles theory,"The anisotropy of the electronic structure of ternary nanolaminate V2GeC is
+investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured
+polarization-dependent emission spectra of V L2,3, C K, Ge M1 and Ge M2,3 in
+V2GeC are compared to those from monocarbide VC and pure Ge. The experimental
+emission spectra are interpreted with calculated spectra using ab initio
+density-functional theory including dipole transition matrix elements.
+Different types of covalent chemical bond regions are revealed; V 3d - C 2p
+bonding at -3.8 eV, Ge 4p - C 2p bonding at -6 eV and Ge 4p - C 2s interaction
+mediated via the V 3d orbitals at -11 eV below the Fermi level. We find that
+the anisotropic effects are high for the 4p valence states and the shallow 3d
+core levels of Ge, while relatively small anisotropy is detected for the V 3d
+states. The macroscopic properties of the V2GeC nanolaminate result from the
+chemical bonds with the anisotropic pattern as shown in this work.",1112.6287v1
+2012-01-16,Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at sqrt(s[NN]) = 2.76 TeV,"Measurements from the CMS experiment at the LHC of dihadron correlations for
+charged particles produced in PbPb collisions at a nucleon-nucleon
+centre-of-mass energy of 2.76 TeV are presented. The results are reported as a
+function of the particle transverse momenta (pt) and collision centrality over
+a broad range in relative pseudorapidity [Delta(eta)] and the full range of
+relative azimuthal angle [Delta(phi)]. The observed two-dimensional correlation
+structure in Delta(eta) and Delta(phi) is characterised by a narrow peak at
+(Delta(eta), Delta(phi)) approximately (0, 0) from jet-like correlations and a
+long-range structure that persists up to at least |Delta(eta)| = 4. An
+enhancement of the magnitude of the short-range jet peak is observed with
+increasing centrality, especially for particles of pt around 1-2 GeV/c. The
+long-range azimuthal dihadron correlations are extensively studied using a
+Fourier decomposition analysis. The extracted Fourier coefficients are found to
+factorise into a product of single-particle azimuthal anisotropies up to pt
+approximately 3-3.5 GeV/c for at least one particle from each pair, except for
+the second-order harmonics in the most central PbPb events. Various orders of
+the single-particle azimuthal anisotropy harmonics are extracted for associated
+particle pt of 1-3 GeV/c, as a function of the trigger particle pt up to 20
+GeV/c and over the full centrality range.",1201.3158v2
+2012-01-16,Azimuthal anisotropies for Au+Au collisions in the parton-hadron transient energy range,"The azimuthal anisotropies of the collective transverse flow of charged
+hadrons are investigated in a wide range of heavy-ion collision energies within
+the microscopic parton-hadron-string dynamics (PHSD) transport approach which
+incorporates explicit partonic degrees of freedom in terms of strongly
+interacting quasiparticles (quarks and gluons) in line with an equation of
+state from lattice QCD as well as the dynamical hadronization and hadronic
+collision dynamics in the final reaction phase. The experimentally observed
+increase of the elliptic flow $v_2$ of charged hadrons with collision energy is
+successfully described in terms of the PHSD approach. The PHSD scaling
+properties of various collective observables are confronted with experimental
+data as well as with hydrodynamic predictions. The analysis of higher-order
+harmonics $v_3$ and $v_4$ in the azimuthal angular distribution shows a similar
+tendency of growing deviations between partonic and purely hadronic models with
+increasing collision energy. This demonstrates that the excitation functions of
+azimuthal anisotropies reflect the increasing role of quark-gluon degrees of
+freedom in the early phase of relativistic heavy-ion collisions. Furthermore,
+the specific variation of the ratio $v_4/(v_2)^2$ with respect to bombarding
+energy, centrality and transverse momentum is found to provide valuable
+information on the underlying dynamics.",1201.3320v2
+2012-01-31,Explorations into the inertial and integral scales of homogeneous axisymmetric turbulence,"A flow generator is described in which homogeneous axisymmetric turbulent air
+flows with varying and fully controllable degrees of anisotropy, including the
+much studied isotropic case, are generated by the combined agitations produced
+by 32 acoustic mixers focusing at the center of the system. The axisymmetric
+turbulence in a central volume of the size of the inertial scale is shown to
+have negligible mean and shear. The Taylor Reynolds number is about 480.
+  The influence of large scale anisotropy on the turbulence is examined from
+three aspects, namely the velocity structure functions, the velocity
+correlation functions, and the integral lengths. The directional dependence of
+two different second order transverse structure functions, in which one of them
+has separations stretched along the axis of symmetry of the turbulence and the
+other one normal to it, is studied. It is shown that the inertial range scaling
+exponents, determined using the extended-self-similarity procedure, and the
+Kolmogorov constants of the two structure functions are unaffected by the
+direction in which the structure functions are measured.
+  Finally, it is found that, except in the isotropic case, the second order
+transverse velocity correlation functions deviate from each other at the large
+scale with increasing anisotropy. A self-similarity argument similar to one
+found in the study of critical phenomena is proposed. It is shown that the
+argument leads to a power-law relationship between the large scale velocity
+fluctuation and the correlation length, with an exponent that depends on the
+inertial range scaling exponent of the turbulence. The data collapse predicted
+by the self-similarity hypothesis is verified. It is demonstrated that the
+value of the power-law exponent is consistent with the value of the inertial
+range scaling exponent.",1201.6412v1
+2012-04-30,Analytic Spectra of CMB Anisotropies and Polarization Generated by Scalar Perturbations in Synchronous Gauge,"We present a detailed analytical calculation of CMB temperature anisotropies
+\alpha_k and polarization \beta_k generated by scalar metric perturbations in
+synchronous gauge, parallel to our previous work with RGW as a generating
+source. This is realized primarily by an analytic time-integration of
+Boltzmann's equation, yielding the closed forms of \alpha_k and \beta_k.
+Approximations, such as the tight-coupling approximation for photons a prior to
+the recombination and the long wavelength limit for scalar perturbations are
+used. The residual gauge modes in scalar perturbations are analyzed and a
+proper joining condition of scalar perturbations at the radiation-matter
+equality is chosen, ensuring the continuity of energy perturbation.
+  The resulting analytic expressions of the multipole moments of polarization
+a^E_l, and of temperature anisotropies a^T_l are explicit functions of the
+scalar perturbations, recombination time, recombination width, photon free
+streaming damping factor, baryon fraction, initial amplitude, primordial scalar
+spectral index, and the running index. These results show that a longer
+recombination width yields higher amplitudes of polarization on large scales
+and more damping on small scales, and that a late recombination time shifts the
+peaks of C^{XX'}_l to larger angular scales.
+  The analytic spectra C^{XX'}_l agree with the numerical ones and with those
+observed by WMAP on large scales (l \lesssim 500), but deviate considerably
+from the numerical results on smaller scales, showing the limitations of our
+approximate analytic calculations. Several possible improvements are pointed
+out for further studies.",1204.6683v1
+2012-05-21,Orbit-based dynamical models of the Sculptor dSph galaxy,"We have developed spherically symmetric dynamical models of dwarf spheroidal
+galaxies using Schwarzschild's orbit superposition method. This type of
+modelling yields constraints both on the total mass distribution (e.g. enclosed
+mass and scale radius) as well as on the orbital structure of the system (e.g.
+velocity anisotropy). This method is thus less prone to biases introduced by
+assumptions in comparison to the more commonly used Jeans modelling, and it
+allows us to derive the dark matter content in a robust way. Here we present
+our results for the Sculptor dwarf spheroidal galaxy, after testing our methods
+on mock data sets. We fit both the second and fourth velocity moment profile to
+break the mass-anisotropy degeneracy. For an NFW dark matter halo profile, we
+find that the mass of Sculptor within 1 kpc is M_1kpc = 1.03 \pm 0.07 x 10^8
+Msol, and that its velocity anisotropy profile is tangentially biased and
+nearly constant with radius. The preferred concentration (c ~ 15) is low for
+its dark matter mass but consistent within the scatter found in N-body
+cosmological simulations. When we let the value of the central logarithmic
+slope \alpha{} vary, we find that the best-fit model has \alpha{} = 0, although
+an NFW cusp or shallower is consistent at 1 \sigma{} confidence level. On the
+other hand, very cuspy density profiles with logarithmic central slopes
+\alpha{} < -1.5 are strongly disfavoured for Sculptor.",1205.4712v2
+2012-06-08,Weak Spin Fluctuation with Finite Wave Vector and Superconducting Gap Symmetry in KxFe2-ySe2: 77Se Nuclear Magnetic Resonance,"We report $^{77}$Se-nuclear magnetic resonance (NMR) results down to
+sufficiently low temperatures under magnetic fields parallel to both the
+$ab$-plane and the c-axis in a paramagnetic/superconducting (PM/SC) phase of
+K$_x$Fe$_{2-y}$Se$_2$. The observation of anisotropy in the orbital part of the
+Knight shift results in the anisotropy of its spin part increasing on
+approaching the transition temperature. The anisotropy of the Korringa relation
+suggests the presence of the weak spin fluctuations with a finite wave vector
+$\bm{q}$, which induce the magnetic fluctuations along the ab-plane at the Se
+site. Such fluctuations do not correspond to the stripe $(\pi,0)$ correlation
+of the Fe moment observed in many Fe-based superconductors, and are not
+contradictory to weak $(\pi,\pi)$ correlations. The nuclear spin-lattice
+relaxation rate $1/T_1$ shows a field-independent $T_1T \sim const.$ behavior
+at low temperatures for $H \parallel ab$, which is attributed to the nonzero
+density of states at the Fermi level and can be explained by the sign-changing
+order parameter even for nodeless gaps. The temperature dependence of $1/T_1$
+is reproduced well by nodeless models with two isotropic gaps or a single
+anisotropic gap. The obtained gap magnitude in the isotropic two-gap model is
+comparable to those obtained in the angle-resolved photoemission spectroscopy
+experiments.",1206.1756v2
+2012-06-09,Deflection of Light and Shapiro Delay: An Equivalent Medium Theory Approach,"We discuss the deflection of light and Shapiro delay under the influence of
+gravity as described by Schwarzschild metric. We obtain an exact expression
+based on the coordinate velocity, as first set forth by Einstein, and present a
+discussion on the effect of velocity anisotropy. We conclude that the
+anisotropy in the coordinate velocity, as the velocity apparent to a distant
+observer, gives rise to a third order error in the deflection angle, so that
+the practical astronomical observations from gravitational lensing data remain
+inconclusive on the anisotropy. However, measurement of Shapiro delay provides
+a fairly convenient way to determine whether the spacetime is optically
+anisotropic for a distant observer or not. We calculate the Shapiro delay for a
+round trip path between Earth and Venus and observe excellent agreement to two
+experimentally reported values measured during a time span of six months in
+1967, without any need to extra fitting parameters. This is while the expected
+delay obtained from an isotropic light velocity as described by Einstein's
+model suffers from much larger errors under similar conditions. This article
+illustrates the usefulness of the equivalent medium theory in understanding of
+general theory of relativity.",1206.1947v1
+2012-06-28,Measuring D_A and H at z=0.35 from the SDSS DR7 LRGs using baryon acoustic oscillations,"We present measurements of the angular diameter distance D_A(z) and the
+Hubble parameter H(z) at z=0.35 using the anisotropy of the baryon acoustic
+oscillation (BAO) signal measured in the galaxy clustering distribution of the
+Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) Luminous Red Galaxies
+(LRG) sample. Our work is the first to apply density-field reconstruction to an
+anisotropic analysis of the acoustic peak. Reconstruction partially removes the
+effects of non-linear evolution and redshift-space distortions in order to
+sharpen the acoustic signal. We present the theoretical framework behind the
+anisotropic BAO signal and give a detailed account of the fitting model we use
+to extract this signal from the data. Our method focuses only on the acoustic
+peak anisotropy, rather than the more model-dependent anisotropic information
+from the broadband power. We test the robustness of our analysis methods on 160
+LasDamas DR7 mock catalogues and find that our models are unbiased at the ~0.2%
+level in measuring the BAO anisotropy. After reconstruction we measure
+D_A(z=0.35)=1050+/-38 Mpc and H(z=0.35)=84.4+/-7.0 km/s/Mpc assuming a sound
+horizon of r_s=152.76 Mpc. Note that these measurements are correlated with a
+correlation coefficient of 0.58. This represents a factor of 1.4 improvement in
+the error on D_A relative to the pre-reconstruction case; a factor of 1.2
+improvement is seen for H.",1206.6732v2
+2012-07-06,Physical properties underlying observed kinematics of satellite galaxies,"We study the kinematics of satellites around isolated galaxies selected from
+the Sloan Digital Sky Survey (SDSS) spectroscopic catalog. Using a model of the
+phase-space density previously measured for the halos of LCDM dark matter
+cosmological simulations, we determine the properties of the halo mass
+distribution and the orbital anisotropy of the satellites as a function of the
+colour-based morphological type and the stellar mass of the central host
+galaxy. We place constraints on the halo mass and the concentration parameter
+of dark matter and the satellite number density profiles. We obtain a
+concentration-mass relation for galactic dark matter haloes that is consistent
+with predictions of a standard LCDM cosmological model. At given halo or
+stellar mass, red galaxies have more concentrated halos than their blue
+counterparts. The fraction of dark matter within a few effective radii is
+minimal for 11.25<log M_star<11.5. The number density profile of the satellites
+appears to be shallower than of dark matter, with the scale radius typically 60
+per cent larger than of dark matter. The orbital anisotropy around red hosts
+exhibits a mild excess of radial motions, in agreement with the typical
+anisotropy profiles found in cosmological simulations, whereas blue galaxies
+are found to be consistent with an isotropic velocity distribution. Our new
+constraints on the halo masses of galaxies are used to provide analytic
+approximations of the halo-to-stellar mass relation for red and blue galaxies.",1207.1647v3
+2012-07-11,Anomalous Workfunction Anisotropy in Ternary Acetylides,"Anomalous anisotropy of workfunction values in ternary alkali metal
+transition metal acetylides is reported. Workfunction values of some
+characteristic surfaces in these emerging semiconducting materials may differ
+by more than $\approx$ 2 eV as predicted by Density Functional Theory
+calculations. This large anisotropy is a consequence of the relative
+orientation of rod-like [MC$_{2}$]$_{\infty}$ negatively charged polymeric
+subunits and the surfaces, with M being a transition metal or metalloid element
+and C$_{2}$ refers to the acetylide ion C$_{2}^{2-}$, with the rods embedded
+into an alkali cation matrix. It is shown that the conversion of the seasoned
+Cs$_{2}$Te photo-emissive material to ternary acetylide Cs$_{2}$TeC$_{2}$
+results in substantial reduction of its $\approx$ 3 eV workfunction down to
+1.71-2.44 eV on the Cs$_{2}$TeC$_{2}$(010) surface while its high quantum yield
+is preserved. Similar low workfunction values are predicted for other ternary
+acetylides as well, allowing for a broad range of applications from improved
+electron- and light-sources to solar cells, field emission displays, detectors
+and scanners.",1207.2512v1
+2012-08-16,High superconducting anisotropy and weak vortex pinning in Co doped LaFeAsO,"Here, we present an electrical transport study in single crystals of
+LaFe$_{0.92}$Co$_{0.08}$AsO ($T_c \simeq 9.1$ K) under high magnetic fields. In
+contrast to most of the previously reported Fe based superconductors, and
+despite its relatively low $T_c$, LaFe$_{1-x}$Co$_x$AsO shows a superconducting
+anisotropy which is comparable to those seen for instance in the cuprates or
+$\gamma_H = H_{c2}^{ab}/H_{c2}^{c} = m_c/m_{ab} \simeq 9$, where $m_c/m_{ab}$
+is the effective mass anisotropy. Although, in the present case and as in all
+Fe based superconductors, $\gamma \rightarrow 1$ as $T \rightarrow 0$. Under
+the application of an external field, we also observe a remarkable broadening
+of the superconducting transition particularly for fields applied along the
+inter-planar direction. Both observations indicate that the low dimensionality
+of LaFe$_{1-x}$Co$_x$AsO is likely to lead to a more complex vortex
+phase-diagram when compared to the other Fe arsenides and consequently, to a
+pronounced dissipation associated with the movement of vortices in a possible
+vortex liquid phase. When compared to, for instance, F-doped compounds
+pertaining to same family, we obtain rather small activation energies for the
+motion of vortices. This suggests that the disorder introduced by doping
+LaFeAsO with F is more effective in pinning the vortices than alloying it with
+Co.",1208.3435v1
+2012-08-30,"High-pressure flux growth, structural, and superconducting properties of LnFeAsO (Ln = Pr, Nd, Sm) single crystals","Single crystals of the LnFeAsO (Ln1111, Ln = Pr, Nd, and Sm) family with
+lateral dimensions up to 1 mm were grown from NaAs and KAs flux at high
+pressure. The crystals are of good structural quality and become
+superconducting when O is partially substituted by F (PrFeAsO1-xFx and
+NdFeAsO1-xFx) or when Fe is substituted by Co (SmFe1-xCoxAsO). From
+magnetization measurements, we estimate the temperature dependence and
+anisotropy of the upper critical field and the critical current density of
+underdoped PrFeAsO0.7F0.3 crystal with Tc = 25 K. Single crystals of
+SmFe1-xCoxAsO with maximal Tc up to 16.3 K for x = 0.08 were grown for the
+first time. From transport and magnetic measurements we estimate the critical
+fields and their anisotropy, and find these superconducting properties to be
+quite comparable to the ones in SmFeAsO1-xFx with a much higher Tc of = 50 K.
+The magnetically measured critical current densities are as high as 109 A/m2 at
+2 K up to 7 T, with indication of the usual fishtail effect. The upper critical
+field estimated from resistivity measurements is anisotropic with slopes of
+-8.7 T/K (H // ab-plane) and -1.7 T/K (H // c-axis). This anisotropy (= 5) is
+similar to that in other Ln1111 crystals with various higher Tc s.",1208.6207v2
+2012-10-07,Tailoring Magnetism of Perpendicularly Magnetized MnxGa Epitaxial Films on GaAs for Practical Applications,"MnxGa films with high perpendicular anisotropy, coercivity and energy product
+have great application potential in ultrahigh-density perpendicular recording,
+permanent magnets, spin-transfer-torque memory and oscillators,
+magneto-resistance sensors and ferromagnetic metal/semiconductor
+heterostructure devices. Here we present a comprehensive diagram of effective
+magnetism-tailoring of perpendicularly magnetized MnxGa films grown on III-V
+semiconductor GaAs by using molecular-beam epitaxy for the first time, by
+systematically investigating the wide-range composition and detailed
+post-growth annealing effects. We show that the (001)-orientated MnxGa films
+with L10 or D022 ordering could be crystallized on GaAs in a very wide
+composition range from x=0.76 to 2.6. L10-ordered MnxGa films show robust
+magnetization, high remanent ratio, giant perpendicular anisotropy, high
+intrinsic and extrinsic coercivity, and large energy product, which make this
+kind of material favorable for perpendicular magnetic recording,
+high-performance spintronic devices and permanent magnet applications. In
+contrast, D022-ordered films exhibit lower perpendicular anisotropy and weaker
+magnetism. Post-growth annealing MnxGa films studies reveal high
+thermal-stability up to 450 oC, and effective tailoring of magnetic properties
+can be realized by prolonging annealing at 450 oC. These results would be
+helpful for understanding this kind of material and designing new spintronic
+devices for specific practical applications.",1210.2062v3
+2012-10-11,Anisotropic universe with anisotropic sources,"We analyze the state space of a Bianchi-I universe with anisotropic sources.
+Here we consider an extended state space which includes null geodesics in this
+background. The evolution equations for all the state observables are derived.
+Dynamical systems approach is used to study the evolution of these equations.
+The asymptotic stable fixed points for all the evolution equations are found.
+We also check our analytic results with numerical analysis of these dynamical
+equations. The evolution of the state observables are studied both in cosmic
+time and using a dimensionless time variable. Then we repeat the same analysis
+with a more realistic scenario, adding the isotropic (dust like dark) matter
+and a cosmological constant (dark energy) to our anisotropic sources, to study
+their co-evolution. The universe now approaches a de~Sitter space
+asymptotically dominated by the cosmological constant. The cosmic microwave
+background anisotropy maps due to shear are also generated in this scenario,
+assuming that the universe contains anisotropic matter along with the usual
+(dark) matter and vacuum (dark) energy since decoupling. We find that they
+contribute dominantly to the CMB quadrupole. We also constrain the current
+level of anisotropy and also search for any cosmic preferred axis present in
+the data. We use the Union~2 Supernovae data to this extent. An anisotropy axis
+close to the mirror symmetry axis seen in the cosmic microwave background data
+from Planck probe is found.",1210.3159v3
+2012-10-11,The anisotropic power spectrum and bispectrum in the f(phi) F^2 mechanism,"A suitable coupling of the inflaton phi to a vector kinetic term F^2 gives
+frozen and scale invariant vector perturbations. We compute the cosmological
+perturbations zeta that result from such coupling by taking into account the
+classical vector field that unavoidably gets generated at large scales during
+inflation. This generically results in a too anisotropic power spectrum of
+zeta. Specifically, the anisotropy exceeds the 1% level (10% level) if
+inflation lasted ~5 e-folds (~50 e-folds) more than the minimal amount required
+to produce the CMB modes. This conclusion applies, among others, to the
+application of this mechanism for magnetogenesis, for anisotropic inflation,
+and for the generation of anisotropic perturbations at the end of inflation
+through a waterfall field coupled to the vector (in this case, the unavoidable
+contribution that we obtain is effective all throughout inflation, and it is
+independent of the waterfall field). For a tuned duration of inflation, a 1%
+(10%) anisotropy in the power spectrum corresponds to an anisotropic bispectrum
+which is enhanced like the local one in the squeezed limit, and with an
+effective local f_{NL} ~3 (~30). More in general, a significant anisotropy of
+the perturbations may be a natural outcome of all models that sustain higher
+than 0 spin fields during inflation.",1210.3257v1
+2012-10-30,Large Stark Effect for Li Donor Spins in Si,"We study the effect of a static electric field on lithium donor spins in
+silicon. The anisotropy of the effective mass leads to the anisotropy of the
+quadratic Stark susceptibility, which we determined using the Dalgarno-Lewis
+exact summation method. The theory is asymptotically exact in the field domain
+below Li-donor ionization threshold, relevant to the Stark-tuning electron spin
+resonance experiments. To obtain the generalized Stark susceptibilities at
+arbitrary fields, we propose a new variational wave function which reproduces
+the exact results in the low-field limit. With the calculated susceptibilities
+at hand, we are able to predict and analyze several important physical effects.
+First, we observe that the energy level shifts due to the quadratic Stark
+effect for Li donors in Si are equivalent to, and can be mapped onto, those
+produced by an external stress.
+  Second, we demonstrate that the Stark effect anisotropy, combined with the
+unique valley-orbit splitting of a Li donor in Si, spin-orbit interaction and
+specially tuned external stress, may lead to a very strong modulation of the
+donor spin $g$-factor by the electric field. Third, we investigate the
+influence of random strains on the $g$-factor shifts and quantify the random
+strain limits and requirements to Si material purity necessary to observe the
+$g$-factor Stark shifts experimentally. Finally, we discuss possible
+implications of our results for quantum information processing with Li spin
+qubits in Si.",1210.8164v1
+2012-11-30,An anisotropic-Alfvenic-turbulence-based solar wind model with proton temperature anisotropy,"How the solar wind is accelerated to its supersonic speed is intimately
+related to how it is heated. Mechanisms based on ion-cyclotron resonance have
+been successful in explaining a large number of observations, those concerning
+the significant ion temperature anisotropy above coronal holes in particular.
+However, they suffer from the inconsistency with turbulence theory which says
+that the turbulent cascade in a low-beta medium like the solar corona should
+proceed in the perpendicular rather than the parallel direction, meaning that
+there is little energy in the ion gyro-frequency range for ions to absorb via
+ion-cyclotron resonance. Recently a mechanism based on the interaction between
+the solar wind particles and the anisotropic turbulence has been proposed,
+where the perpendicular proton energy addition is via the stochastic heating
+(Chandran et al. 2011). We extend this promising mechanism by properly
+accounting for the effect of proton temperature anisotropy on the propagation
+of Alfven waves, for the radiative losses of electron energy, and for the field
+line curvature that naturally accompanies solar winds in the corona. While this
+mechanism was shown in previous studies to apply to the polar fast solar wind,
+we demonstrate here for the first time that it applies also to the slow wind
+flowing along field lines bordering streamer helmets.",1211.7136v1
+2012-12-12,"Holographic quark-antiquark potential in hot, anisotropic Yang-Mills plasma","Using the gauge/gravity duality we calculate the heavy quark-antiquark
+potential in a hot, anisotropic and strongly coupled Yang-Mills plasma in
+(3+1)-dimensions. As the anisotropic medium we take a deformed version of
+\mathcal{N} = 4 super Yang-Mills theory at finite temperature following a
+recent work where the dual type IIB supergravity solution is also proposed. We
+turn on a small value of the anisotropy parameter, for which the gravity dual
+is known analytically (perturbatively), and compute the velocity-dependent
+quark-antiquark interaction potential when the pair is moving through the
+plasma with a velocity v. By setting v = 0 we recover the static
+quark-antiquark potential. We numerically study how the potential is modified
+in the presence of anisotropy. We further show numerically how the
+quark-antiquark separation (both in the static and the velocity-dependent case)
+and hence, the screening length gets modified by anisotropy. We discuss various
+cases depending upon the direction of the dipole and the direction of its
+propagation and make a comparative study of these cases. We are also able to
+obtain an analytical expression for the screening length of the dipole moving
+in a hot, anisotropic plasma in a special case.",1212.2769v2
+2012-12-18,Interplay of anisotropies of momentum distribution and mean field in heavy-ion collisions,"Two important parametrizations of momentum-dependent nucleonic fields,
+proposed for the simulations of central heavy-ion collisions, one by Gale et
+al. and the other by Welke et al., suffer from practical limitations. The first
+gives rise to mean fields isotropic in momentum, even when underlying momentum
+distributions are anisotropic, making descriptions of early nonequilibrium
+stages of collisions unrealistic. The second parametrization gives rise to
+anisotropic mean fields, but is computationally expensive, because the mean
+field has to be computed separately for every location of a nucleon in phase
+space, through folding. Here we construct a parametrization of the nucleonic
+mean field that yields an anisotropic mean field for an anisotropic momentum
+distribution and is inexpensive computationally. To demonstrate the versatility
+of our parametrization, we take the case of results from the parametrization by
+Welke et al. and attempt to approximate them. In arriving at a suitable
+anisotropic mean-field potential, we draw, on one hand, from the idea behind
+the parametrization of Gale et al., of a separable expansion of the potential
+energy, and, on the other, from the idea of a parallel expansion of the energy
+and mean field in anisotropy. We show that using our novel parametrization we
+can qualitatively and partially quantitatively reproduce the features of the
+mean-field parametrization of Welke et al.. This opens up the possibility of
+exploring the effects of mean-field anisotropy in collisions, without the
+penalty of computational cost behind the folding parametrization.",1212.4460v3
+2012-12-19,Metallicity Bias in the Kinematics of the Milky Way Stellar Halo,"Here we study the metallicity bias in the velocity dispersions, the derived
+quantity called anisotropy and the mean azimuthal velocity profiles of the
+Milky Way stellar halo using Blue Horizontal Branch (BHB) stars taken from
+SDSS/SEGUE survey. The comparatively metal-rich sample ([Fe/H]>-2) has prograde
+motion and is found to have an offset of 40 km/s in the mean azimuthal velocity
+with respect to a metal-poor sample ([Fe/H]<=-2) which has retrograde motion.
+The difference in rotation between the most metal-poor and most metal-rich
+population was found to be around 65 km/s. For galactocentric distances r<16
+kpc, an offset in velocity dispersion profiles and anisotropy can also be seen.
+In the inner regions, the metal-poor population is in average tangential orbit;
+however, anisotropy is found to decrease monotonically with radius independent
+of metallicity. Beyond r = 16 kpc, both the metal-rich and the metal-poor
+samples are found to have tangential motion. The metallicity bias in the
+kinematics of the halo stars qualitatively supports the co-existence of at
+least two-components in the halo having different formation history e.g.
+in-situ formation and formation by accretion.",1212.4576v2
+2013-01-21,Importance of both spin and orbital fluctuations in BaFe2(As1-xPx)2 : Evidence from superconducting gap anisotropy,"In the iron pnictide superconductors, two distinct unconventional mechanisms
+of superconductivity have been put forth: One is mediated by spin fluctuations
+leading to the s+- state with sign change of superconducting gap between the
+hole and electron bands, and the other is orbital fluctuations which favor the
+s++ state without sign reversal. Here we report direct observation of peculiar
+momentum-dependent anisotropy in the superconducting gap from angle-resolved
+photoemission spectroscopy (ARPES) in BaFe2(As1-xPx)2 (Tc=30 K). The large
+anisotropy found only in the electron Fermi surface (FS) and the nearly
+isotropic gap on the entire hole FSs are together consistent with modified s+-
+gap with nodal loops, which can be theoretically reproduced by considering both
+spin and orbital fluctuations whose competition generates the gap modulation.
+This indicates that these two fluctuations are nearly equally important to the
+high-Tc superconductivity in this system.",1301.4818v1
+2013-01-28,The contribution of the Warm-Hot Intergalactic Medium to the CMB anisotropies via the Sunyaev-Zeldovich effect,"Cosmological hydrodynamical simulations predict that a large fraction of all
+baryons reside within mildly non-linear structures with temperatures in the
+range $10^{5}-10^{7}$K. As the gas is highly ionized, it could be detected by
+the temperature anisotropies generated on the Cosmic Microwave Background
+radiation. We refine our previous estimates of the thermal Sunyaev-Zeldovich
+effect by introducing a non-polytropic equation of state to model the
+temperature distribution of the shock heated gas derived from
+temperature-density phase diagrams of different hydrodynamical simulations.
+Depending on the specific model, the Comptonization parameter varies in the
+range $10^{-7}\le y_c \le 2\times 10^{-6}$, compatible with the FIRAS upper
+limit. This amplitude is in agreement with a simple toy model constructed to
+estimate the average effect induced by filaments of ionized gas. Using the
+log-normal probability density function we calculate the correlation function
+and the power spectrum of the temperature anisotropies generated by the WHIM
+filaments. For a wide range of the parameter space, the maximum amplitude of
+the radiation power spectrum is $(\ell+1)\ell C_{\ell}/2\pi =0.7-70(\mu K)^2$
+at $\ell \approx 200-500$. This amplitude scales with baryon density, Hubble
+constant and the amplitude of the matter power spectrum $\sigma_8$ as
+$[(\ell+1)\ell C_\ell]_{\mathrm{max}}/2\pi \propto \sigma_8^{2.6}(\Omega_b
+h)^2$. Since the thermal Sunyaev-Zeldovich effect has a specific frequency
+dependence, we analyze the possibility of detecting this component with the
+forthcoming Planck data.",1301.6546v1
+2013-02-04,Radial evolution of the wave-vector anisotropy of solar wind turbulence between 0.3 and 1 AU,"We present observations of the power spectral anisotropy in wave-vector space
+of solar wind turbulence, and study how it evolves in interplanetary space with
+increasing heliocentric distance. For this purpose we use magnetic field
+measurements made by the Helios-2 spacecraft at three positions between 0.29
+and 0.9 AU. To derive the power spectral density (PSD) in $(k_\parallel,
+k_\bot)$-space based on single-satellite measurements is a challenging task not
+yet accomplished previously. Here we derive the spectrum
+$\rm{PSD}_{\rm{2D}}$($\rm{k}_\parallel$, $\rm{k}_\bot$) from the spatial
+correlation function $\rm{CF}_{\rm{2D}}(r_\parallel, r_\bot)$ by a
+transformation according to the projection-slice theorem. We find the so
+constructed PSDs to be distributed in k-space mainly along a ridge that is more
+inclined toward the $\rm{k}_\bot$ than $\rm{k}_\parallel$ axis, a new result
+which probably indicates preferential cascading of turbulent energy along the
+$\rm{k}_\bot$ direction. Furthermore, this ridge of the distribution is found
+to gradually get closer to the $\rm{k}_\bot$ axis, as the outer scale length of
+the turbulence becomes larger while the solar wind flows further away from the
+Sun. In the vicinity of the $\rm{k}_\parallel$ axis, there appears a minor
+spectral component that probably corresponds to quasi-parallel Alfv\'enic
+fluctuations. Their relative contribution to the total spectral density tends
+to decrease with radial distance. These findings suggest that solar wind
+turbulence undergoes an anisotropic cascade transporting most of its magnetic
+energy towards larger $\rm{k}_\bot$, and that the anisotropy in the inertial
+range is radially developing further at scales that are relatively far from the
+ever increasing outer scale.",1302.0699v1
+2013-02-05,Loop Quantum Cosmology of Bianchi I Model in $\barμ$ and $\barμ'$ Schemes with Higher Order Holonomy Corrections,"The detailed formulation of loop quantum cosmology with higher order holonomy
+corrections has been constructed recently in the homogeneous and isotropic
+spacetime, yet it is important to extend the higher order holonomy corrections
+to include the effects of anisotropy which typically grow during the collapsing
+phase. In this paper we investigate the Bianchi I model in $\bar{\mu}'$ scheme
+which truly captures the regularization of the Hamiltonian constraint. To
+compare with the earlier works and provide a comparison with the $\bar{\mu}'$
+scheme, we also investigate the $\bar{\mu}$ scheme although it has many
+disadvantages. First we construct the effective dynamics with higher order
+holonomy corrections in a massless scalar field, then we extend it to the
+inclusion of arbitrary matter. Besides that, we also analyze the behavior of
+the anisotropy during the evolution of the universe. We find that in the
+$\bar{\mu}'$ scheme, the singularity is never approached and the quantum bounce
+is generic as in the isotropic case, regardless of the order of the holonomy
+corrections. Some differences in the bouncing phase of the two schemes are also
+found out. It is also shown that in the two schemes the behavior of the
+anisotropy is not the same before and after the bounce.",1302.1014v2
+2013-03-08,Measurement of Cosmic Ray Spectrum and Anisotropy with the ARGO-YBJ experiment,"The combined measurement of the cosmic ray (CR) energy spectrum and
+anisotropy in their arrival direction distribution needs the knowledge of the
+elemental composition of the radiation to discriminate between different origin
+and propagation models. Important information on the CR mass composition can be
+obtained studying the EAS muon content through the measurement of the CR rate
+at different zenith angles.
+  In this paper we report on the observation of the anisotropy of galactic CRs
+at different angular scales with the ARGO-YBJ experiment. We report also on the
+study of the primary CR rate for different zenith angles. The light component
+(p+He) has been selected and its energy spectrum measured in the energy range
+(5 - 200) TeV for quasi-vertical events. With this analysis for the first time
+a ground-based measurement of the CR spectrum overlaps data obtained with
+direct methods for more than one energy decade, thus providing a solid
+anchorage to the CR spectrum measurements carried out by EAS arrays in the knee
+region.
+  Finally, a preliminary study of the non-attenuated shower component at a
+zenith angle $\theta >$ 70$^{\circ}$ (through the observation of the so-called
+horizantal air showers) is presented.",1303.2049v1
+2013-03-22,The signature of the Warm Hot Intergalactic Medium in WMAP and the forthcoming PLANCK data,"We compute the cross-correlation between the Warm-Hot Intergalactic Medium
+and maps of Cosmic Microwave Background temperature anisotropies using a
+log-normal probability density function to describe the weakly non-linear
+matter density field. We search for this contribution in the data measured by
+the Wilkinson Microwave Anisotropy Probe. We use a template of projected matter
+density reconstructed from the Two-Micron All-Sky Redshift Survey as a tracer
+of the electron distribution. The spatial distribution of filaments is modeled
+using the recently developed Augmented Lagrangian Perturbation Theory. On the
+scales considered here, the reconstructed density field is very well described
+by the assumed log-normal distribution function. We predict that the
+cross-correlation will have an amplitude of $0.03-0.3\mu$K. The measured value
+is close to $1.5\mu$K, compatible with random alignments between structure in
+the template and in the temperature anisotropy data. Using the W1 Differencing
+Assembly to remove this systematic gives a residual correlation dominated by
+Galactic foregrounds. Planck could detect the Warm-Hot Medium if it is well
+traced by the density field reconstructed from galaxy surveys. The 217GHz
+channel will allow to eliminate spurious contributions and its large frequency
+coverage can show the sign change from the Rayleigh-Jeans to the Wien part of
+the spectrum, characteristic of the thermal Sunyaev-Zeldovich effect.",1303.5623v2
+2013-04-04,Learning from Nature to Improve the Heat Generation of Iron-Oxide Nanoparticles for Magnetic Hyperthermia Applications,"The performance of magnetic nanoparticles is intimately entwined with their
+structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique
+way of engineering the magnetic response by modifying the strength of the
+dipolar interactions between particles. Here we report on an experimental and
+theoretical analysis of magnetic hyperthermia, a rapidly developing technique
+in medical research and oncology. Experimentally, we demonstrate that
+single-domain cubic iron oxide particles resembling bacterial magnetosomes have
+superior magnetic heating efficiency compared to spherical particles of similar
+sizes. Monte Carlo simulations at the atomic level corroborate the larger
+anisotropy of the cubic particles in comparison with the spherical ones, thus
+evidencing the beneficial role of surface anisotropy in the improved heating
+power. Moreover we establish a quantitative link between the particle
+assembling, the interactions and the heating properties. This knowledge opens
+new perspectives for improved hyperthermia, an alternative to conventional
+cancer therapies.",1304.1298v1
+2013-05-03,Multiplicity and transverse-momentum dependence of two- and four-particle correlations in pPb and PbPb collisions,"Measurements of two- and four-particle angular correlations for charged
+particles emitted in pPb collisions are presented over a wide range in
+pseudorapidity and full azimuth. The data, corresponding to an integrated
+luminosity of approximately 31 inverse nanobarns, were collected during the
+2013 LHC pPb run at a nucleon-nucleon center-of-mass energy of 5.02 TeV by the
+CMS experiment. The results are compared to 2.76 TeV semi-peripheral PbPb
+collision data, collected during the 2011 PbPb run, covering a similar range of
+particle multiplicities. The observed correlations are characterized by the
+near-side (abs(Delta(phi)~0) associated pair yields and the azimuthal
+anisotropy Fourier harmonics (v[n]). The second-order (v[2]) and third-order
+(v[3]) anisotropy harmonics are extracted using the two-particle azimuthal
+correlation technique. A four-particle correlation method is also applied to
+obtain the value of v[2] and further explore the multi-particle nature of the
+correlations. Both associated pair yields and anisotropy harmonics are studied
+as a function of particle multiplicity and transverse momentum. The associated
+pair yields, the four-particle v[2], and the v[3] become apparent at about the
+same multiplicity. A remarkable similarity in the v[3] signal as a function of
+multiplicity is observed between the pPb and PbPb systems. Predictions based on
+the color glass condensate and hydrodynamic models are compared to the
+experimental results.",1305.0609v3
+2013-05-03,"Co2 FeAl thin films grown on MgO substrates: Correlation between static, dynamic and structural properties","Co2FeAl (CFA) thin films with thickness varying from 10 nm to 115 nm have
+been deposited on MgO(001) substrates by magnetron sputtering and then capped
+by Ta or Cr layer. X-rays diffraction (XRD) revealed that the cubic $[001]$ CFA
+axis is normal to the substrate and that all the CFA films exhibit full
+epitaxial growth. The chemical order varies from the $B2$ phase to the $A2$
+phase when decreasing the thickness. Magneto-optical Kerr effect (MOKE) and
+vibrating sample magnetometer measurements show that, depending on the field
+orientation, one or two-step switchings occur. Moreover, the films present a
+quadratic MOKE signal increasing with the CFA thickness, due to the increasing
+chemical order. Ferromagnetic resonance, MOKE transverse bias initial inverse
+susceptibility and torque (TBIIST) measurements reveal that the in-plane
+anisotropy results from the superposition of a uniaxial and of a fourfold
+symmetry term. The fourfold anisotropy is in accord with the crystal structure
+of the samples and is correlated to the biaxial strain and to the chemical
+order present in the films. In addition, a large negative perpendicular
+uniaxial anisotropy is observed. Frequency and angular dependences of the FMR
+linewidth show two magnon scattering and mosaicity contributions, which depend
+on the CFA thickness. A Gilbert damping coefficient as low as 0.0011 is found.",1305.0714v1
+2013-05-16,Effect of doping on the magnetostructural ordered phase of iron arsenides: A comparative study of the resistivity anisotropy in the doped BaFe$_2$As$_2$ with doping into three different sites,"In order to unravel a role of doping in the iron-based superconductors, we
+investigated the in-plane resistivity for BaFe$_2$As$_2$ doped at either of the
+three different lattice sites, Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$,
+BaFe$_2$(As$_{1-x}$P$_x$)$_2$, and Ba$_{1-x}$K$_x$Fe$_2$As$_2$, focusing on the
+doping effect in the low-temperature antiferromagnetic/orthorhombic (AFO)
+phase. A major role of doping in the high-temperature paramagnetic/tetragonal
+(PT) phase is known to change the Fermi surface by supplying charge carriers or
+by exerting chemical pressure. In the AFO phase, we found a clear correlation
+between the magnitude of residual resistivity and resistivity anisotropy. This
+indicates that the resistivity anisotropy originates from the anisotropic
+impurity scattering from dopant atoms. The magnitude of residual resistivity is
+also found to be a parameter controlling the suppression rate of AFO ordering
+temperature $T_s$. Therefore, the dominant role of doping in the AFO phase is
+to introduce disorder to the system, distinct from that in the PT phase.",1305.3744v1
+2013-06-28,A unified solution to the anisotropy and gradient problems,"The Fermi-LAT collaboration recently confirmed a discrepancy between the
+observed longitudinal profile of gamma-ray diffuse emission from the Galaxy and
+that computed with numerical codes assuming that Cosmic Rays (CRs) are produced
+by Galactic supernova remnants; the accurate Fermi-LAT measurements make this
+anomaly hardly explainable in terms of conventional diffusion schemes.
+Moreover, experimental data from both Muon detector and Extensive Air Shower
+experiments about the large scale dipole anisotropy of CRs can hardly be
+compatible with model predictions within the framework of conventional
+isotropic and homogeneous propagation. We argue that, accounting for a well
+physically motivated correlation between the CR escape time and the spatially
+dependent magnetic turbulence power, it is possible to solve both problems at
+the same time in a very natural way. Indeed, by exploiting this correlation, we
+find propagation models that fit a wide set of CR primary and secondary
+spectra, and consistently reproduce the CR anisotropy in the energy range 100
+GeV - 10 TeV and the gamma-ray longitude distribution recently measured by
+Fermi-LAT.",1306.6849v1
+2013-07-04,Approximation methods in Loop Quantum Cosmology: From Gowdy cosmologies to inhomogeneous models in Friedmann-Robertson-Walker geometries,"We develop approximation methods in the hybrid quantization of the Gowdy
+model with linear polarization and a massless scalar field, for the case of
+three-torus spatial topology. The loop quantization of the homogeneous
+gravitational sector of the Gowdy model (according to the improved dynamics
+prescription) and the presence of inhomogeneities lead to a very complicated
+Hamiltonian constraint. Therefore, the extraction of physical results calls for
+the introduction of well justified approximations. We first show how to
+approximate the homogeneous part of the Hamiltonian constraint, corresponding
+to Bianchi I geometries, as if it described a Friedmann-Robertson-Walker (FRW)
+model corrected with anisotropies. This approximation is valid in the
+high-energy sector of the FRW geometry (concerning its contribution to the
+constraint) and for anisotropy profiles that are sufficiently smooth. In
+addition, for certain families of states associated to regimes of physical
+interest, with negligible effects of the anisotropies and small
+inhomogeneities, one can approximate the Hamiltonian constraint of the
+inhomogeneous system by that of an FRW geometry with a relatively simple matter
+content, and then obtain its solutions.",1307.1420v2
+2013-07-29,Feebly Self-Interacting Cold Dark Matter: New theory for the Core-Halo structure in GLSB Galaxies,"We explore the low energy cosmological dynamics of feebly self-interacting
+cold dark matter and propose a new simple explanation for the rotation curves
+of the core-halo model in massive LSB (Low Surface brightness)galaxies. We
+argue in favor of the truly collisionless nature of cold dark matter,which is
+feebly,self-interacting at small scales between epochs of equality and
+recombination.For this, we assume a model, wherein strongly coupled
+baryon-radiation plasma ejects out of small regions of concentrated cold dark
+matter without losing its equilibrium. We use the Merscerskii equation i.e. the
+variable mass formalism of classical dynamics.We obtain new results relating
+the oscillations in the CMB anisotropy to the ejection velocity of the
+baryon-radiation plasma,which can be useful tool for numerical work for
+exploring the second peak of CMB. Based on this model, we discuss the growth of
+perturbations in such a feebly self-interacting,cold dark matter both in the
+Jeans theory and in the expanding universe using Newton's theory.We obtain an
+expression for the growth of fractional perturbations in cold dark matter,which
+reduce to the standard result of perturbation theory for late recombination
+epochs. We see the effect of the average of the perturbations in the cold dark
+matter potential on the cosmic microwave background temperature anisotropy that
+originated at redshifts between equality and recombination i.e. 1100 < z <
+z_{eq}. Also we obtain an expression for the Sachs-Wolfe effect,i.e. the CMB
+temperature anisotropy at decoupling in terms of the average of the
+perturbations in cold dark matter potential.",1307.7469v2
+2013-08-24,Spin-chain magnetism and uniform Dzyaloshinsky-Moriya anisotropy in BaV$_3$O$_8$,"We report on the microscopic magnetic model of a spin-1/2 magnet
+BaV$_3$O$_8$. In contrast to earlier phenomenological analysis, our
+density-functional band-structure calculations combined with quantum
+Monte-Carlo simulations establish a relatively simple and non-frustrated model
+of weakly coupled spin chains with the intrachain coupling of $J\sim$ 38 K and
+the Neel temperature of $T_N\sim$ 6 K, both in excellent agreement with the
+experiment. The intrachain coupling between the spin-1/2 V$^{+4}$ ions takes
+place via two contiguous V$^{+5}$O$_4$ tetrahedra forming an extended
+superexchange pathway with the V$^{+4}$--V$^{+4}$ distance of 7.44 A.
+Surprisingly, this pathway is preferred over shorter V$^{+4}$--V$^{+4}$
+connections, owing to peculiarities in the interacting orbitals of the magnetic
+V$^{+4}$ ions and V$^{+5}$ ions that are non-magnetic, but feature low-lying
+$3d$ states contributing to the superexchange process. We also note that the
+crystal structure of BaV$_3$O$_8$ supports the long-sought uniform arrangement
+of Dzyaloshinsky-Moriya (DM) couplings on a spin-1/2 chain. While our
+calculations yield only a weak DM anisotropy in BaV$_3$O$_8$, the crystal
+structure of this compound provides a suitable framework for the search of spin
+chains with the uniform DM anisotropy in other compounds of the vanadate
+family.",1308.5305v2
+2013-09-26,Reionization on Large Scales IV: Predictions for the 21 cm signal incorporating the light cone effect,"We present predictions for the 21 cm brightness temperature power spectrum
+during the Epoch of Reionization (EoR). We discuss the implications of the
+""light cone"" effect, which incorporates evolution of the neutral hydrogen
+fraction and 21 cm brightness temperature along the line of sight. Using a
+novel method calibrated against radiation-hydrodynamic simulations, we model
+the neutral hydrogen density field and 21 cm signal in large volumes ($L = 2$
+Gpc/$h$). The inclusion of the light cone effect leads to a relative decrease
+of about 50% in the 21 cm power spectrum on all scales. We also find that the
+effect is more prominent at the midpoint of reionization and later. The light
+cone effect also can introduce an anisotropy along the line of sight. By
+decomposing the 3D power spectrum into components perpendicular to and along
+the line of sight, we find that in our fiducial reionization model, there is no
+significant anisotropy. However, parallel modes can contribute up to 40% more
+power for shorter reionization scenarios. The scales on which the light cone
+effect is relevant are comparable to scales where one measures the baryon
+acoustic oscillation. We argue that due to its large comoving scale and
+introduction of anisotropy, the light cone effect is important when considering
+redshift space distortions and future application to the Alcock-Paczynski test
+for the determination of cosmological parameters.",1309.7056v3
+2013-09-28,Synthetic Multiferroic Interconnects for Magnetic Logic Circuits,"In this work, we consider the possibility of using synthetic multiferroics
+comprising piezoelectric and magnetostrictive materials as an interconnect for
+nano magnetic logic circuits. The proposed interconnect resembles a parallel
+plate capacitor filled with a piezoelectric, where one of the plates is made of
+a magnetoelastic material. The operation of the interconnect is based on the
+effect of stress-mediated anisotropy modulation, where an electric field
+applied across the piezoelectric material produces stress, which, in turn,
+affects the anisotropy field in the magnetostrictive material. We present the
+results of numerical modeling illustrating signal propagation through the
+interconnect. The model combines electric and magnetic parts, where the
+electric part describes the distribution of an electric field through the
+piezoelectric and the magnetic part describes the change of magnetization in
+the magnetoelastic layer. The model is based on the Landau-Lifshitz-Gilbert
+equation with the electric field dependent anisotropy term included. The
+utilization of the electro-magnetic coupling makes it possible to amplify
+magnetic signal during its propagation via energy conversion from the electric
+to magnetic domains. Potentially, synthetic multiferroic interconnects can be
+implemented in a variety of spin-based devices ensuring reliable and low-energy
+consuming data transmission. According to the estimates, the group velocity of
+magnetic signals may be up to 100 km/s with energy dissipation less than aJ per
+bit per 100nm. The fundamental limits and practical shortcoming of the proposed
+approach are also discussed.",1309.7399v1
+2013-09-29,Magnetic Properties of Two-dimensional Nanodots: Ground State and Phase Transition,"We study the effect of perpendicular single-ion anisotropy,
+$-As_{\text{z}}^2$, on the ground-state structure and finite-temperature
+properties of a two-dimensional magnetic nanodot in presence of a dipolar
+interaction of strength $D$. By a simulated annealing Monte Carlo method, we
+show that in the ground state a vortex core perpendicular to the nanodot plane
+emerges already in the range of moderate anisotropy values above a certain
+threshold level. In the giant-anisotropy regime the vortex structure is
+superseded by a stripe domain structure with stripes of alternate domains
+perpendicular to the surface of the sample. We have also observed an
+intermediate stage between the vortex and stripe structures, with satellite
+regions of tilted nonzero perpendicular magnetization around the core. At
+finite temperatures, at small $A$, we show by Monte Carlo simulations that
+there is a transition from the the in-plane vortex phase to the disordered
+phase characterized by a peak in the specific heat and the vanishing vortex
+order parameter. At stronger $A$, we observe a discontinuous transition with a
+large latent heat from the in-plane vortex phase to perpendicular stripe
+ordering phase before a total disordering at higher temperatures. In the regime
+of perpendicular stripe domains, namely with giant $A$, there is no phase
+transition at finite $T$: the stripe domains are progressively disordered with
+increasing $T$. Finite-size effects are shown and discussed.",1309.7631v1
+2013-10-01,Field Induced Magnetic Ordering and Single-ion Anisotropy in the Quasi-1D Haldane Chain Compound SrNi2V2O8: A Single Crystal investigation,"Field-induced magnetic ordering in the Haldane chain compound
+SrNi$_{2}$V$_{2}$O$_{8}$ and effect of anisotropy have been investigated using
+single crystals. Static susceptibility, inelastic neutron scattering,
+high-field magnetization, and low temperature heat-capacity studies confirm a
+non-magnetic spin-singlet ground state and a gap between the singlet ground
+state and triplet excited states. The intra-chain exchange interaction is
+estimated to be $J \sim 8.9{\pm}$0.1 meV. Splitting of the dispersions into two
+modes with minimum energies 1.57 and 2.58 meV confirms the existence of
+single-ion anisotropy $D(S^z){^2}$. The value of {\it D} is estimated to be
+$-0.51{\pm}0.01$ meV and the easy axis is found to be along the
+crystallographic {\it c}-axis. Field-induced magnetic ordering has been found
+with two critical fields [$\mu_0H_c^{\perp c} = 12.0{\pm}$0.2 T and
+$\mu_0H_c^{\parallel c} = 20.8{\pm}$0.5 T at 4.2 K]. Field-induced
+three-dimensional magnetic ordering above the critical fields is evident from
+the heat-capacity, susceptibility, and high-field magnetization study. The
+Phase diagram in the {\it H-T} plane has been obtained from the high-field
+magnetization. The observed results are discussed in the light of theoretical
+predictions as well as earlier experimental reports on Haldane chain compounds.",1310.0221v1
+2013-10-17,Wake in anisotropic Quark-Gluon Plasma,"We calculate the wake in charge density and the wake potential due to the
+passage of a fast parton in an anisotropic quark gluon plasma(AQGP). For the
+sake of simplicity small $\xi$(anisotropic parameter) limit has been
+considered. When the velocity($v$) of the jet is parallel to the anisotropy
+direction(${\hat n}$) and remains below the phase velocity($v_p$), the wake in
+induced charge density shows a little oscillatory behavior in AQGP, contrary to
+the isotropic case. With the jet velocity greater than the phase velocity, the
+oscillatory behavior increases with $\xi$. Also for $v>v_p$ one observes a
+clear modification of the cone-like structure in presence of anisotropy. For
+the parallel direction in the backward region, the depth of the wake potential
+decreases with the increase of $\xi$ for $v<v_p$ and the potential becomes
+modified Coulomb-like for higher values of $\xi$. In the forward region, the
+potential remains modified Coulomb-like with the change in magnitude for
+nonzero $\xi$, for both $v>v_p$ and $v<v_p$. In the perpendicular direction,
+the wake potential is symmetric in the forward and backward regions. With the
+increase of $\xi$, the depth of negative minimum is moving away from the origin
+irrespective of the jet velocity. On the other hand when the jet velocity is
+perpendicular to the anisotropy direction, we find significant changes in the
+case of both wake charge density and potential in comparison to the isotropic
+case.",1310.4657v1
+2014-01-22,The Ellipsoidal Universe in the Planck Satellite Era,"Recent Planck data confirm that the cosmic microwave background displays the
+quadru-pole power suppression together with large scale anomalies. Progressing
+from previous results, that focused on the quadrupole anomaly, we strengthen
+the proposal that the slightly anisotropic ellipsoidal universe may account for
+these anomalies. We solved at large scales the Boltzmann equation for the
+photon distribution functions by taking into account both the effects of the
+inflation produced primordial scalar perturbations and the anisotropy of the
+geometry in the ellipsoidal universe. We showed that the low quadrupole
+temperature correlations allowed us to fix the eccentricity at decoupling,
+$e_{\rm dec} \, = \, (0.86 \, \pm \, 0.14) \, 10^{-2}$, and to constraint the
+direction of the symmetry axis. We found that the anisotropy of the geometry of
+the universe contributes only to the large scale temperature anisotropies
+without affecting the higher multipoles of the angular power spectrum.
+Moreover, we showed that the ellipsoidal geometry of the universe induces
+sizable polarization signal at large scales without invoking the reionization
+scenario. We explicitly evaluated the quadrupole TE and EE correlations. We
+found an average large scale polarization $\Delta T_{pol} \, = \, (1.20 \, \pm
+\, 0.38) \; \mu K $. We point out that great care is needed in the experimental
+determination of the large-scale polarization correlations since the average
+temperature polarization could be misinterpreted as foreground emission
+leading, thereby, to a considerable underestimate of the cosmic microwave
+background polarization signal.",1401.5627v3
+2014-02-17,A review of two-band superconductivity: materials and effects on the thermodynamic and reversible mixed-state properties,"Two-band superconductivity has become an important topic over the last ten
+years. Extensive experimental and theoretical studies started with MgB2 and are
+now focused on the iron-based and other new superconductors. In this review, I
+describe how important thermodynamic, reversible mixed-state, and other
+superconducting properties are changed by two-band and, for comparison, by
+other effects such as anisotropy in a single-band material or an energy gap
+structure different from the conventional s-wave symmetry. The work consists of
+three main parts, in which I review (i) theoretical models and what they
+predict for experimentally accessible properties in the two-band and other
+scenarios, (ii) experimental methods applied for investigating superconducting
+properties and the results obtained in potential two-band materials, and (iii)
+materials, for which two- or multi-band superconductivity has been suggested.
+It is shown that two-band effects appear in most of the analyzed properties and
+that they can be quite significant but usually fade away as interband
+interactions increase. Anisotropy often leads to similar modifications in
+single-band superconductors, which is why the distinction of two-band and
+anisotropy effects is usually difficult, particularly when the temperature
+dependence of the quantities is examined. In contrast, the field dependent
+effects are more often different and thus more often allow a reliable
+distinction between the models.",1402.3956v1
+2014-02-27,Enhanced Stability of Skyrmions in Two-Dimensional Chiral Magnets with Rashba Spin-Orbit Coupling,"Recent developments have led to an explosion of activity on skyrmions in
+three-dimensional (3D) chiral magnets. Experiments have directly probed these
+topological spin textures, revealed their nontrivial properties, and led to
+suggestions for novel applications. However, in 3D the skyrmion crystal phase
+is observed only in a narrow region of the temperature-field phase diagram. We
+show here, using a general analysis based on symmetry, that skyrmions are much
+more readily stabilized in two-dimensional (2D) systems with Rashba spin-orbit
+coupling. This enhanced stability arises from the competition between field and
+easy-plane magnetic anisotropy and results in a nontrivial structure in the
+topological charge density in the core of the skyrmions. We further show that,
+in a variety of microscopic models for magnetic exchange, the required
+easy-plane anisotropy naturally arises from the same spin-orbit coupling that
+is responsible for the chiral Dzyaloshinskii-Moriya interactions. Our results
+are of particular interest for 2D materials like thin films, surfaces, and
+oxide interfaces, where broken surface-inversion symmetry and Rashba spin-orbit
+coupling naturally lead to chiral exchange and easy-plane compass anisotropy.
+Our theory gives a clear direction for experimental studies of 2D magnetic
+materials to stabilize skyrmions over a large range of magnetic fields down to
+T=0.",1402.7082v2
+2014-03-03,Pressure-induced ferromagnetism with strong Ising-type anisotropy in YbCu$_2$Si$_2$,"We report dc magnetic measurements on YbCu$_2$Si$_2$ at pressures above 10
+GPa using a miniature ceramic anvil cell. YbCu$_2$Si$_2$ shows a
+pressure-induced transition from the non-magnetic to a magnetic phase at 8 GPa.
+We find a spontaneous dc magnetization in the pressure-induced phase above 9.4
+GPa. The pressure dependence of the ferromagnetic transition temperature T_C
+and the spontaneous magnetic moment m_0 at 2.0 K have been determined. The
+value of m_0 in the present macroscopic measurement is less than half of that
+determined via Mossbauer experiment. The difference may be attributed to
+spatial phase separation between the ferromagnetic and paramagnetic phases.
+This separation suggests that the pressure-induced phase boundary between the
+paramagnetic and ferromagnetic states is of first order. Further, we have
+studied the magnetic anisotropy in the pressure-induced ferromagnetic state.
+The effect of pressure on the magnetization with magnetic field along the
+magnetic easy $c$-axis is much larger than for field along the hard $a$-axis in
+the tetragonal structure. The pressure-induced phase has strong Ising-type
+uniaxial anisotropy, consistent with the two crystal electric field (CEF)
+models proposed for YbCu$_2$Si$_2$.",1403.0290v2
+2014-03-19,"Erosion of Globular Cluster Systems: The Influence of Radial Anisotropy, Central Black Holes and Dynamical Friction","We present the adaptable MUESLI code for investigating dynamics and erosion
+processes of globular clusters (GCs) in galaxies. MUESLI follows the orbits of
+individual clusters and applies internal and external dissolution processes to
+them. Orbit integration is based on the self-consistent field method in
+combination with a time-transformed leapfrog scheme, allowing us to handle
+velocity-dependent forces like triaxial dynamical friction. In a first
+application, the erosion of globular cluster systems (GCSs) in elliptical
+galaxies is investigated. Observations show that massive ellipticals have rich,
+radially extended GCSs, while some compact dwarf ellipticals contain no GCs at
+all. For several representative examples, spanning the full mass scale of
+observed elliptical galaxies, we quantify the influence of radial anisotropy,
+galactic density profiles, SMBHs, and dynamical friction on the GC erosion
+rate. We find that GC number density profiles are centrally flattened in less
+than a Hubble time, naturally explaining observed cored GC distributions. The
+erosion rate depends primarily on a galaxy's mass, half-mass radius and radial
+anisotropy. The fraction of eroded GCs is nearly 100% in compact, M 32 like
+galaxies and lowest in extended and massive galaxies. Finally, we uncover the
+existence of a violent tidal disruption dominated phase which is important for
+the rapid build-up of halo stars.",1403.4946v1
+2014-04-22,Results from the Wilkinson Microwave Anisotropy Probe,"The Wilkinson Microwave Anisotropy Probe (WMAP) mapped the distribution of
+temperature and polarization over the entire sky in five microwave frequency
+bands. These full-sky maps were used to obtain measurements of temperature and
+polarization anisotropy of the cosmic microwave background with the
+unprecedented accuracy and precision. The analysis of two-point correlation
+functions of temperature and polarization data gives determinations of the
+fundamental cosmological parameters such as the age and composition of the
+universe, as well as the key parameters describing the physics of inflation,
+which is further constrained by three-point correlation functions. WMAP
+observations alone reduced the flat $\Lambda$ cold dark matter ($\Lambda$CDM)
+cosmological model (six) parameter volume by a factor of >68,000 compared with
+pre-WMAP measurements. The WMAP observations (sometimes in combination with
+other astrophysical probes) convincingly show the existence of non-baryonic
+dark matter, the cosmic neutrino background, flatness of spatial geometry of
+the universe, a deviation from a scale-invariant spectrum of initial scalar
+fluctuations, and that the current universe is undergoing an accelerated
+expansion. The WMAP observations provide the strongest ever support for
+inflation; namely, the structures we see in the universe originate from quantum
+fluctuations generated during inflation.",1404.5415v2
+2014-04-22,Order-by-disorder and spin-orbital liquids in a distorted Heisenberg-Kitaev model,"The microscopic modeling of spin-orbit entangled $j=1/2$ Mott insulators such
+as the layered hexagonal Iridates Na$_2$IrO$_3$ and Li$_2$IrO$_3$ has spurred
+an interest in the physics of Heisenberg-Kitaev models. Here we explore the
+effect of lattice distortions on the formation of the collective spin-orbital
+states which include not only conventionally ordered phases but also gapped and
+gapless spin-orbital liquids. In particular, we demonstrate that in the
+presence of spatial anisotropies of the exchange couplings conventionally
+ordered states are formed through an order-by-disorder selection which is not
+only sensitive to the type of exchange anisotropy but also to the relative
+strength of the Heisenberg and Kitaev couplings. The spin-orbital liquid phases
+of the Kitaev limit -- a gapless phase in the vicinity of spatially isotropic
+couplings and a gapped Z$_2$ phase for a dominant spatial anisotropy of the
+exchange couplings -- show vastly different sensitivities to the inclusion of a
+Heisenberg exchange. While the gapless phase is remarkably stable, the gapped
+Z$_2$ phase quickly breaks down in what might be a rather unconventional phase
+transition driven by the simultaneous condensation of its elementary
+excitations.",1404.5490v2
+2014-06-10,Resolving the mass--anisotropy degeneracy of the spherically symmetric Jeans equation II: optimum smoothing and model validation,"The spherical Jeans equation is widely used to estimate the mass content of a
+stellar systems with apparent spherical symmetry. However, this method suffers
+from a degeneracy between the assumed mass density and the kinematic anisotropy
+profile, $\beta(r)$. In a previous work, we laid the theoretical foundations
+for an algorithm that combines smoothing B-splines with equations from dynamics
+to remove this degeneracy. Specifically, our method reconstructs a unique
+kinematic profile of $\sigma_{rr}^2$ and $\sigma_{tt}^2$ for an assumed free
+functional form of the potential and mass density $(\Phi,\rho)$ and given a set
+of observed line-of-sight velocity dispersion measurements, $\sigma_{los}^2$.
+In Paper I (submitted to MNRAS: MN-14-0101-MJ) we demonstrated the efficiency
+of our algorithm with a very simple example and we commented on the need for
+optimum smoothing of the B-spline representation; this is in order to avoid
+unphysical variational behaviour when we have large uncertainty in our data. In
+the current contribution we present a process of finding the optimum smoothing
+for a given data set by using information of the behaviour from known ideal
+theoretical models. Markov Chain Monte Carlo methods are used to explore the
+degeneracy in the dynamical modelling process. We validate our model through
+applications to synthetic data for systems with constant or variable
+mass-to-light ratio $\Upsilon$. In all cases we recover excellent fits of
+theoretical functions to observables and unique solutions. Our algorithm is a
+robust method for the removal of the mass-anisotropy degeneracy of the
+spherically symmetric Jeans equation for an assumed functional form of the mass
+density.",1406.2546v1
+2014-08-12,Thermal Conduction in Single-Layer Black Phosphorus: Highly Anisotropic?,"The single-layer black phosphorus is characteristic for its puckered
+structure, which has leaded to highly anisotropy in its optical, electronic,
+and mechanical properties. We report, using the non-equilibrium Green's
+function approach and the first-principles method, that the anisotropy in the
+thermal conduction is very weak in the single-layer black phosphorus -- the
+difference between two in-plane directions is less than 4%. Our phonon
+calculations disclose that the two in-plane acoustic phonon branches have lower
+group velocities in the direction perpendicular to the pucker, as the black
+phosphorus is softer in this direction, leading to a weakening effect for the
+thermal conductance in the perpendicular direction. However, the out-of-plane
+acoustic phonon branch behaviors abnormally; i.e., the group velocity of this
+phonon branch is higher in the perpendicular direction, although the
+single-layer black phosphorus is softer in this direction. The abnormal
+behavior of the out-of-plane phonon branch is closely related to the highly
+anisotropic Poisson's ratio in the single-layer black phosphorus. As a result
+of the counteraction between the in-plane phonon modes and the out-of-plane
+phonon mode, the thermal conductance in the perpendicular direction is weaker
+than the parallel direction, but the anisotropy is pretty small.",1408.2622v2
+2014-08-18,Constraining topological defects with temperature and polarization anisotropies,"We analyse the possible contribution of topological defects to cosmic
+microwave anisotropies, both temperature and polarisation. We allow for the
+presence of both inflationary scalars and tensors, and of polarised dust
+foregrounds that may contribute to or dominate the B-mode polarisation signal.
+We confirm and quantify our previous statements that topological defects on
+their own are a poor fit to the B-mode signal. However, adding topological
+defects to a models with a tensor component or a dust component improves the
+fit around $\ell=200$. Fitting simultaneously to both temperature and
+polarisation data, we find that textures fit almost as well as tensors
+($\Delta\chi^2 = 2.0$), while Abelian Higgs strings are ruled out as the sole
+source of the B-mode signal at low $\ell$. The 95% confidence upper limits on
+models combining defects and dust are $G\mu < 2.7\times 10^{-7}$ (Abelian Higgs
+strings), $G\mu < 9.8\times 10^{-7}$ (semilocal strings) and $G\mu < 7.3\times
+10^{-7}$ (textures), a small reduction on the $Planck$ bounds. The most
+economical fit overall is obtained by the standard $\Lambda$CDM model with a
+polarised dust component.",1408.4126v2
+2014-09-02,Switching of Perpendicularly Polarized Nanomagnets with Spin Orbit Torque without an External Magnetic Field by Engineering a Tilted Anisotropy,"Spin orbit torque (SOT) provides an efficient way of generating spin current
+that promises to significantly reduce the current required for switching
+nanomagnets. However, an in-plane current generated SOT cannot
+deterministically switch a perpendicularly polarized magnet due to symmetry
+reasons. On the other hand, perpendicularly polarized magnets are preferred
+over in-plane magnets for high-density data storage applications due to their
+significantly larger thermal stability in ultra-scaled dimensions. Here we show
+that it is possible switch a perpendicularly polarized magnet by SOT without
+needing an external magnetic field. This is accomplished by engineering an
+anisotropy in the magnets such that the magnetic easy axis slightly tilts away
+from the film-normal. Such a tilted anisotropy breaks the symmetry of the
+problem and makes it possible to switch the magnet deterministically. Using a
+simple Ta/CoFeB/MgO/Ta heterostructure, we demonstrate reversible switching of
+the magnetization by reversing the polarity of the applied current. This
+demonstration presents a new approach for controlling nanomagnets with spin
+orbit torque.",1409.0620v3
+2014-09-02,The Fortuitous Latitude of the Pierre Auger Observatory and Telescope Array for Reconstructing the Quadrupole Moment,"Determining anisotropies in the arrival directions of cosmic rays at the
+highest energy is an important task in astrophysics. It is common and useful to
+partition the sky into spherical harmonics as a measure of anisotropy. The two
+lowest nontrivial spherical harmonics, the dipole and the quadrupole, are of
+particular interest, since these distributions encapsulate a dominant single
+source and a plane of sources, as well as offering relatively high statistics.
+The best experiments for the detection of ultra high energy cosmic rays
+currently are all ground-based, with highly nonuniform exposures on the sky
+resulting from the fixed experimental locations on the earth. This nonuniform
+exposure increases the complexity and error in inferring anisotropies. It turns
+out that there is an optimal latitude for an experiment at which nonuniform
+exposure does not diminish the inference of the quadrupole moment. We derive
+the optimal latitude, and find that (presumably by a fortuitous coincidence)
+this optimal latitude runs through the largest cosmic ray experiment, Pierre
+Auger Observatory (PAO) in the Southern Hemisphere, and close to the largest
+cosmic ray experiment in the Northern Hemisphere, Telescope Array (TA).
+Consequently, assuming a quadrupole distribution, PAO and TA can reconstruct
+the cosmic ray quadrupole distribution to a high precision, without concern for
+their partial sky exposure.",1409.0883v2
+2014-09-10,Magnetohydrodynamic normal mode analysis of plasma with equilibrium pressure anisotropy,"In this work, we generalise linear magnetohydrodynamic (MHD) stability theory
+to include equilibrium pressure anisotropy in the fluid part of the analysis. A
+novel 'single-adiabatic' (SA) fluid closure is presented which is complementary
+to the usual 'double-adiabatic' (CGL) model and has the advantage of naturally
+reproducing exactly the MHD spectrum in the isotropic limit. As with MHD and
+CGL, the SA model neglects the anisotropic perturbed pressure and thus loses
+non-local fast-particle stabilisation present in the kinetic approach. Another
+interesting aspect of this new approach is that the stabilising terms appear
+naturally as separate viscous corrections leaving the isotropic SA closure
+unchanged. After verifying the self-consistency of the SA model, we re-derive
+the projected linear MHD set of equations required for stability analysis of
+tokamaks in the MISHKA code. The cylindrical wave equation is derived
+analytically as done previously in the spectral theory of MHD and clear
+predictions are made for the modification to fast-magnetosonic and slow ion
+sound speeds due to equilibrium anisotropy.",1409.2980v1
+2014-09-12,Naturally large tensor-to-scalar ratio in inflation,"Recently, BICEP2 measurements of the cosmic microwave background (CMB)
+$B$-mode polarization at degree angular scales has indicated the presence of
+tensor modes with a high tensor-to-scalar ratio of $r=0.2$ when assuming nearly
+scale-invariant tensor and scalar spectra, although the signal may be
+contaminated by dust emission as implied by the recent {\em Planck}
+polarization data. This result is in conflict with the {\em Planck} best-fit
+Lambda Cold Dark Model with $r<0.11$. Due to the fact that inflaton has to be
+interacting with other fields so as to convert its potential energy into
+radiation to reheat the Universe, the interacting inflaton may result in a
+suppression of the scalar spectrum at large scales. This suppression has been
+used to explain the observed low quadrupole in the CMB anisotropy. In this
+paper, we show that a combination of the tensor modes measured by BICEP2 and
+the large-scale suppressed scalar modes contributes to the CMB anisotropy in
+such a way that the resultant CMB anisotropy and polarization power spectra are
+consistent with both {\em Planck} and BICEP2 data. We also project our findings
+to cases in which $r$ may become reduced in future CMB polarization
+measurements.",1409.3661v2
+2014-10-24,Probing the epoch of pre-reionization by cross-correlating cosmic microwave and infrared background anisotropies,"The epoch of first star formation and the state of the intergalactic medium
+(IGM) at that time are not directly observable with current telescopes. The
+radiation from those early sources is now part of the Cosmic Infrared
+Background (CIB) and, as these sources ionize the gas around them, the IGM
+plasma would produce faint temperature anisotropies in the Cosmic Microwave
+Background (CMB) via the thermal Sunyaev-Zeldovich (TSZ) effect. While these
+TSZ anisotropies are too faint to be detected, we show that the
+cross-correlation of maps of source-subtracted CIB fluctuations from {\it
+Euclid}, with suitably constructed microwave maps at different frequencies can
+probe the physical state of the gas during reionization and test/constrain
+models of the early CIB sources. We identify the frequency-combined
+CMB-subtracted microwave maps from space and ground-based instruments to show
+that they can be cross-correlated with the forthcoming all-sky {\it Euclid} CIB
+maps to detect the cross-power at scales $\sim 5'-60'$ with the signal/noise of
+up to $S/N\sim 4-8$ depending on the contribution to the Thomson optical depth
+during those pre-reionization epochs ($\Delta \tau\simeq 0.05$) and the
+temperature of IGM (up to $\sim10^4$K). Such a measurement would offer a new
+window to explore emergence and physical properties of these first light
+sources.",1410.6619v2
+2014-11-05,On the Origin of Near-Infrared Extragalactic Background Light Anisotropy,"Extragalactic background light (EBL) anisotropy traces variations in the
+total production of photons over cosmic history, and may contain faint,
+extended components missed in galaxy point source surveys. Infrared EBL
+fluctuations have been attributed to primordial galaxies and black holes at the
+epoch of reionization (EOR), or alternately, intra-halo light (IHL) from stars
+tidally stripped from their parent galaxies at low redshift. We report new EBL
+anisotropy measurements from a specialized sounding rocket experiment at 1.1
+and 1.6 micrometers. The observed fluctuations exceed the amplitude from known
+galaxy populations, are inconsistent with EOR galaxies and black holes, and are
+largely explained by IHL emission. The measured fluctuations are associated
+with an EBL intensity that is comparable to the background from known galaxies
+measured through number counts, and therefore a substantial contribution to the
+energy contained in photons in the cosmos.",1411.1411v1
+2014-11-11,Effect of magnetic anisotropy on spin-dependent thermoelectric effects in nanoscopic systems,"Conventional and spin-related thermoelectric effects in electronic transport
+through a nanoscopic system exhibiting magnetic anisotropy $-$with both
+uniaxial and transverse components$-$ are studied theoretically in the linear
+response regime. In particular, a magnetic tunnel junction with a large-spin
+impurity $-$either a magnetic atom or a magnetic molecule$-$ embedded in the
+barrier is considered as an example. Owing to magnetic interaction with the
+impurity, conduction electrons traversing the junction can scatter on the
+impurity, which effectively can lead to angular momentum and energy exchange
+between the electrons and the impurity. As we show, such processes have a
+profound effect on the thermoelectric response of the system. Specifically, we
+present a detailed analysis of charge, spin and thermal conductance, together
+with the Seebeck and spin Seebeck coefficients (thermopowers). Since the
+scattering mechanism also involves processes when electrons are inelastically
+scattered back to the same electrode, one can expect the flow of spin and
+energy also in the absence of charge transport through the junction. This, in
+turn, results in a finite spin thermopower, and the magnetic anisotropy plays a
+key role for this effect to occur.",1411.2741v2
+2014-11-20,Anisotropic inflation reexamined: upper bound on broken rotational invariance during inflation,"The presence of a light vector field coupled to a scalar field during
+inflation makes a distinct prediction: the observed correlation functions of
+the cosmic microwave background (CMB) become statistically anisotropic. We
+study the implications of the current bound on statistical anisotropy derived
+from the Planck 2013 CMB temperature data for such a model. The previous
+calculations based on the attractor solution indicate that the magnitude of
+anisotropy in the power spectrum is proportional to $N^2$, where $N$ is the
+number of $e$-folds of inflation counted from the end of inflation. In this
+paper, we show that the attractor solution is not compatible with the current
+bound, and derive new predictions using another branch of anisotropic
+inflation. In addition, we improve upon the calculation of the mode function of
+perturbations by including the leading-order slow-roll corrections. We find
+that the anisotropy is roughly proportional to
+$[2(\varepsilon_H+4\eta_H)/3-4(c-1)]^{-2}$, where $\varepsilon_H$ and $\eta_H$
+are the usual slow-roll parameters and $c$ is the parameter in the model,
+regardless of the form of potential of an inflaton field. The bound from Planck
+implies that breaking of rotational invariance during inflation (characterized
+by the background homogeneous shear divided by the Hubble rate) is limited to
+be less than ${\cal O}(10^{-9})$. This bound is many orders of magnitude
+smaller than the amplitude of breaking of time translation invariance, which is
+observed to be ${\cal O}(10^{-2})$.",1411.5489v2
+2014-11-30,An experimental test of the viscous anisotropy hypothesis for partially molten rocks,"Chemical differentiation of rocky planets occurs by melt segregation away
+from the region of melting. The mechanics of this process, however, are complex
+and incompletely understood. In partially molten rocks undergoing shear
+deformation, melt pockets between grains align coherently in the stress field;
+it has been hypothesized that this anisotropy in microstructure creates an
+anisotropy in the viscosity of the aggregate. With the inclusion of anisotropic
+viscosity, continuum, two-phase-flow models reproduce the emergence and angle
+of melt-enriched bands that form in laboratory experiments. In the same
+theoretical context, these models also predict sample-scale melt migration due
+to a gradient in shear stress. Under torsional deformation, melt is expected to
+segregate radially inward. Here we present new torsional deformation
+experiments on partially molten rocks that test this prediction.
+Microstructural analyses of the distribution of melt and solid reveal a radial
+gradient in melt fraction, with more melt toward the centre of the cylinder.
+The extent of this radial melt segregation grows with progressive strain,
+consistent with theory. The agreement between theoretical prediction and
+experimental observation provides a validation of this theory, which is
+critical to understanding the large-scale geodynamic and geochemical evolution
+of Earth.",1412.0203v1
+2014-12-11,Cosmological constraints from the redshift dependence of the Alcock-Paczynski test: galaxy density gradient field,"We propose a method based on the redshift dependence of the Alcock-Paczynski
+(AP) test to measure the expansion history of the Universe. It uses the
+isotropy of the galaxy density gradient field to constrain cosmological
+parameters. If the density parameter $\Omega_m$ or the dark energy equation of
+state $w$ are incorrectly chosen, the gradient field appears to be anisotropic
+with the degree of anisotropy varying with redshift. We use this effect to
+constrain the cosmological parameters governing the expansion history of the
+Universe. Although redshift-space distortions (RSD) induced by galaxy peculiar
+velocities also produce anisotropies in the gradient field, these effects are
+close to uniform in magnitude over a large range of redshift. This makes the
+redshift variation of the gradient field anisotropy relatively insensitive to
+the RSD. By testing the method on mock surveys drawn from the Horizon Run 3
+cosmological N-body simulations, we demonstrate that the cosmological
+parameters can be estimated without bias. Our method is complementary to the
+baryon acoustic oscillation or topology methods as it depends on $D_AH$, the
+product of the angular diameter distance and the Hubble parameter.",1412.3564v3
+2014-12-12,Anisotropic Superconducting Gap and Elongated Vortices with Caroli-De-Gennes-Matricon States in the New Superconductor Ta4Pd3Te16,"The superconducting state is formed by the condensation of a large number of
+Cooper pairs. The normal state electronic properties can give significant
+influence on the superconducting state. For usual type-II superconductors, the
+vortices are cylinder like with a round cross-section. For many two dimensional
+superconductors, such as Cuprates, 2H-NbSe$_2$ etc., albeit the in-plane
+anisotropy, the vortices generally have a round shape. In this paper we report
+results based on the scanning tunneling microscopy/spectroscopy measurements on
+a newly discovered superconductor Ta$_4$Pd$_3$Te$_{16}$. The chain like
+conducting channels of PdTe$_2$ in Ta$_4$Pd$_3$Te$_{16}$ make a significant
+anisotropy of the in-plane Fermi velocity. We suggest at least one anisotropic
+superconducting gap with gap minima or possible node exists in this multiband
+system. In addition, elongated vortices are observed with an anisotropy of
+$\xi_{\parallel b}/\xi_{\perp b}\approx 2.5$. Clear Caroli-de-Gennes-Matricon
+states are also observed within the vortex cores. Our results will initiate the
+study on the elongated vortices and superconducting mechanism in the new
+superconductor Ta$_4$Pd$_3$Te$_{16}$.",1412.3993v1
+2015-02-03,Transitions to valence-bond solid order in a honeycomb lattice antiferromagnet,"We use Quantum Monte-Carlo methods to study the ground state phase diagram of
+a S=1/2 honeycomb lattice magnet in which a nearest-neighbor antiferromagnetic
+exchange J (favoring N\'eel order) competes with two different multi-spin
+interaction terms: a six-spin interaction Q_3 that favors columnar valence-bond
+solid (VBS) order, and a four-spin interaction Q_2 that favors staggered VBS
+order. For Q_3 ~ Q_2 >> J, we establish that the competition between the two
+different VBS orders stabilizes N\'eel order in a large swathe of the phase
+diagram even when J is the smallest energy-scale in the Hamiltonian. When Q_3
+>> (Q_2,J) (Q_2 >> (Q_3,J)), this model exhibits at zero temperature phase
+transition from the N\'eel state to a columnar (staggered) VBS state. We
+establish that the N\'eel-columnar VBS transition is continuous for all values
+of Q_2, and that critical properties along the entire phase boundary are
+well-characterized by critical exponents and amplitudes of the non-compact CP^1
+(NCCP^1) theory of deconfined criticality, similar to what is observed on a
+square lattice. However, a surprising three-fold anisotropy of the phase of the
+VBS order parameter at criticality, whose presence was recently noted at the
+Q_2=0 deconfined critical point, is seen to persist all along this phase
+boundary. We use a classical analogy to explore this by studying the critical
+point of a three-dimensional XY model with a four-fold anisotropy field which
+is known to be weakly irrelevant at the three-dimensional XY critical point. In
+this case, we again find that the critical anisotropy appears to saturate to a
+nonzero value over the range of sizes accessible to our simulations.",1502.01035v1
+2015-03-25,Anisotropy of Thermal Conductivity of Free-Standing Reduced Graphene Oxide Films Annealed at High Temperature,"We investigated thermal conductivity of free-standing reduced graphene oxide
+films subjected to a high-temperature treatment of up to 1000 C. It was found
+that the high-temperature annealing dramatically increased the in-plane thermal
+conductivity, K, of the films from 3 W/mK to 61 W/mK at room temperature. The
+cross-plane thermal conductivity, Kc, revealed an interesting opposite trend of
+decreasing to a very small value of 0.09 W/mK in the reduced graphene oxide
+films annealed at 1000 C. The obtained films demonstrated an exceptionally
+strong anisotropy of the thermal conductivity, K/Kc ~ 675, which is
+substantially larger even than in the high-quality graphite. The electrical
+resistivity of the annealed films reduced to 1 - 19 Ohms/sq. The observed
+modifications of the in-plane and cross-plane thermal conductivity components
+resulting in an unusual K/Kc anisotropy were explained theoretically. The
+theoretical analysis suggests that K can reach as high as ~500 W/mK with the
+increase in the sp2 domain size and further reduction of the oxygen content.
+The strongly anisotropic heat conduction properties of these films can be
+useful for applications in thermal management.",1503.07239v1
+2015-05-05,Elastic anisotropy and Poisson's ratio of solid helium under pressure,"The elastic moduli, elastic anisotropy coefficients, sound velocities and
+Poisson's ratio of hcp solid helium have been calculated using density
+functional theory in generalized gradient approximation (up to $30$ TPa), and
+pair+triple semi-empirical potentials (up to 100 GPa). Zero-point vibrations
+have been treated in the Debye approximation assuming $^4$He isotope (we
+exclude the quantum-crystal region at very low pressures from consideration).
+Both methods give a reasonable agreement with the available experimental data.
+Our calculations predict significant elastic anisotropy of helium ($\triangle P
+\approx 1.14$, $\triangle S_1 \approx 1.7$, $\triangle S_2 \approx 0.93$ at low
+pressures). Under terapascal pressures helium becomes more elastically
+isotropic. At the metallization point there is a sharp feature in the elastic
+modulus $C_S$, which is the stiffness with respect to the isochoric change of
+the $c/a$ ratio. This is connected with the previously obtained sharp minimum
+of the $c/a$ ratio at the metallization point.
+  Our calculations confirm the previously measured decrease of the Poisson's
+ratio with increasing pressure. This is not a quantum effect, as the same sign
+of the pressure effect was obtained when we disregarded zero-point vibrations.
+At TPa pressures Poisson's ratio reaches the value of $0.31$ at the theoretical
+metallization point ($V_{mol}=0.228$ cm$^3$/mol, $p=17.48$ TPa) and $0.29$ at
+30 TPa. For $p=0$ we predict a Poisson's ratio of $0.38$ which is in excellent
+agreement with the low-$p$-low-$T$ experimental data.",1505.00927v3
+2015-05-06,Anisotropy of the solar network magnetic field around the average supergranule,"Supergranules in the quiet Sun are outlined by a web-like structure of
+enhanced magnetic field strength, the so-called magnetic network. We aim to map
+the magnetic network field around the average supergranule near disk center. We
+use observations of the line-of-sight component of the magnetic field from the
+Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory
+(SDO). The average supergranule is constructed by coaligning and averaging over
+3000 individual supergranules. We determine the positions of the supergranules
+with an image segmentation algorithm that we apply on maps of the horizontal
+flow divergence measured using time-distance helioseismology. In the center of
+the average supergranule the magnetic (intranetwork) field is weaker by about
+2.2 Gauss than the background value (3.5 Gauss), whereas it is enhanced in the
+surrounding ring of horizontal inflows (by about 0.6 Gauss on average). We find
+that this network field is significantly stronger west (prograde) of the
+average supergranule than in the east (by about 0.3 Gauss). With time-distance
+helioseismology, we find a similar anisotropy. The observed anisotropy of the
+magnetic field adds to the mysterious dynamical properties of solar
+supergranulation.",1505.01427v2
+2015-05-11,Biases in the determination of dynamical parameters of star clusters: today and in the Gaia era,"The structural and dynamical properties of star clusters are generally
+derived by means of the comparison between steady-state analytic models and the
+available observables. With the aim of studying the biases of this approach, we
+fitted different analytic models to simulated observations obtained from a
+suite of direct N-body simulations of star clusters in different stages of
+their evolution and under different levels of tidal stress to derive mass, mass
+function and degree of anisotropy. We find that masses can be
+under/over-estimated up to 50% depending on the degree of relaxation reached by
+the cluster, the available range of observed masses and distances of radial
+velocity measures from the cluster center and the strength of the tidal field.
+The mass function slope appears to be better constrainable and less sensitive
+to model inadequacies unless strongly dynamically evolved clusters and a
+non-optimal location of the measured luminosity function are considered. The
+degree and the characteristics of the anisotropy developed in the N-body
+simulations are not adequately reproduced by popular analytic models and can be
+detected only if accurate proper motions are available. We show how to reduce
+the uncertainties in the mass, mass-function and anisotropy estimation and
+provide predictions for the improvements expected when Gaia proper motions will
+be available in the near future.",1505.02598v1
+2015-05-21,Radially anisotropic systems with $r^{-α}$ forces: equilibrium states,"We continue the study of collisionless systems governed by additive
+$r^{-\alpha}$ interparticle forces by focusing on the influence of the force
+exponent $\alpha$ on radial orbital anisotropy. In this preparatory work we
+construct the radially anisotropic Osipkov-Merritt phase-space distribution
+functions for self-consistent spherical Hernquist models with $r^{-\alpha}$
+forces and $1\leq\alpha<3$. The resulting systems are isotropic at the center
+and increasingly dominated by radial orbits at radii larger than the anisotropy
+radius $r_a$. For radially anisotropic models we determine the minimum value of
+the anisotropy radius $r_{ac}$ as a function of $\alpha$ for phase-space
+consistency (such that the phase-space distribution function is nowhere
+negative for $r_a\geq r_{ac}$). We find that $r_{ac}$ decreases for decreasing
+$\alpha$, and that the amount of kinetic energy that can be stored in the
+radial direction relative to that stored in the tangential directions for
+marginally consistent models increases for decreasing $\alpha$. In particular,
+we find that isotropic systems are consistent in the explored range of
+$\alpha$. By means of direct $N$-body simulations we finally verify that the
+isotropic systems are also stable.",1505.05713v1
+2015-05-27,Full-Wave Algorithm to Model Effects of Bedding Slopes on the Response of Subsurface Electromagnetic Geophysical Sensors near Unconformities,"We propose a full-wave pseudo-analytical numerical electromagnetic (EM)
+algorithm to model subsurface induction sensors, traversing planar-layered
+geological formations of arbitrary EM material anisotropy and loss, which are
+used, for example, in the exploration of hydrocarbon reserves. Unlike past
+pseudo-analytical planar-layered modeling algorithms that impose parallelism
+between the formation's bed junctions however, our method involves judicious
+employment of Transformation Optics techniques to address challenges related to
+modeling relative slope (i.e., tilting) between said junctions (including
+arbitrary azimuth orientation of each junction). The algorithm exhibits this
+flexibility, both with respect to loss and anisotropy in the formation layers
+as well as junction tilting, via employing special planar slabs that coat each
+""flattened"" (i.e., originally tilted) planar interface, locally redirecting the
+incident wave within the coating slabs to cause wave fronts to interact with
+the flattened interfaces as if they were still tilted with a specific,
+user-defined orientation. Moreover, since the coating layers are homogeneous
+rather than exhibiting continuous material variation, a minimal number of these
+layers must be inserted and hence reduces added simulation time and
+computational expense. As said coating layers are not reflectionless however,
+they do induce artificial field scattering that corrupts legitimate field
+signatures due to the (effective) interface tilting. Numerical results, for two
+half-spaces separated by a tilted interface, quantify error trends versus
+material and sensor characteristics. We finally exhibit responses of sensors
+traversing three-layered media, where we vary the anisotropy, loss, and
+relative tilting of the formations and explore the sensitivity of the sensor's
+complex-valued measurements.",1505.07407v2
+2015-06-12,Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures,"Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts
+extensive attentions due to its non-volatility, high density and low power
+consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel
+junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well
+as a large value of perpendicular magnetic anisotropy (PMA). It has been
+experimentally proven that a capping layer coating on CoFeB layer is essential
+to obtain a strong PMA. However, the physical mechanism of such effect remains
+unclear. In this paper, we investigate the origin of the PMA in
+MgO/CoFe/metallic capping layer structures by using a first-principles
+computation scheme. The trend of PMA variation with different capping materials
+agrees well with experimental results. We find that interfacial PMA in the
+three-layer structures comes from both the MgO/CoFe and CoFe/capping layer
+interfaces, which can be analyzed separately. Furthermore, the PMAs in the
+CoFe/capping layer interfaces are analyzed through resolving the magnetic
+anisotropy energy by layer and orbital. The variation of PMA with different
+capping materials is attributed to the different hybridizations of both d and p
+orbitals via spin-orbital coupling. This work can significantly benefit the
+research and development of nanoscale STT-MRAM.",1506.04078v4
+2015-06-15,Spin-Induced Polarizations and Non-Reciprocal Directional Dichroism of Multiferroic BiFeO$_3$,"A microscopic model for the room-temperature multiferroic BiFeO$_3$ that
+includes two Dzyaloshinskii-Moriya interactions and single-ion anisotropy along
+the ferroelectric polarization predicts both the zero-field spectroscopic modes
+as well as their splitting and evolution in a magnetic field. Due to
+simultaneously broken time-reversal and spatial-inversion symmetries, the
+absorption of light changes as the magnetic field or the direction of light
+propagation is reversed. We discuss three physical mechanisms that may
+contribute to this absorption asymmetry known as non-reciprocal directional
+dichroism: the spin current, magnetostriction, and single-ion anisotropy. We
+conclude that the non-reciprocal directional dichroism in \BF is dominated by
+the spin-current polarization and is insensitive to the magnetostriction and
+easy-axis anisotropy. With three independent spin-current parameters, our model
+accurately describes the non-reciprocal directional dichroism observed for
+magnetic field along $[1,-1,0]$. Since some modes are almost transparent to
+light traveling in one direction but opaque for light traveling in the opposite
+direction, BiFeO$_3$ can be used as a room-temperature optical diode at certain
+frequencies in the GHz to THz range. Our work demonstrates that an analysis of
+the non-reciprocal directional dichroism spectra based on an effective spin
+model supplemented by first-principles calculations can produce a quantitative
+microscopic theory of the magnetoelectric couplings in multiferroic materials.",1506.04595v2
+2015-06-17,Stellar Velocity Dispersion and Anisotropy of the Milky Way Inner Halo,"We measure the three components of velocity dispersion,
+$\sigma_{R},\sigma_{\theta},\sigma_{\phi}$, for stars within 6 < R < 30 kpc of
+the Milky Way using a new radial velocity sample from the MMT telescope. We
+combine our measurements with previously published data so that we can more
+finely sample the stellar halo. We use a maximum likelihood statistical method
+for estimating mean velocities, dispersions, and covariances assuming only that
+velocities are normally distributed. The alignment of the velocity ellipsoid is
+consistent with a spherically symmetric gravitational potential. From the
+spherical Jeans equation, the mass of the Milky Way is M(<12 kpc) =
+$1.3\times10^{11}$ M$_{\odot}$ with an uncertainty of 40%. We also find a
+region of discontinuity, 15 < R < 25 kpc, where the estimated velocity
+dispersions and anisotropies diverge from their anticipated values, confirming
+at high significance the break observed by others. We argue that this break in
+anisotropy is physically explained by coherent stellar velocity structure in
+the halo, such as the Sgr stream. To significantly improve our understanding of
+halo kinematics will require combining radial velocities with future Gaia
+proper motions.",1506.05369v2
+2015-06-21,Fast magnetic field amplification in the early Universe: growth of collisionless plasma instabilities in turbulent media,"In this work we report a numerical study of the cosmic magnetic field
+amplification due to collisionless plasma instabilities. The collisionless
+magnetohydrodynamic equations derived account for the pressure anisotropy that
+leads, in specific conditions, to the firehose and mirror instabilities. We
+study the time evolution of seed fields in turbulence under the influence of
+such instabilities. An approximate analytical time evolution of magnetic field
+is provided. The numerical simulations and the analytical predictions are
+compared. We found that i) amplification of magnetic field was efficient in
+firehose unstable turbulent regimes, but not in the mirror unstable models, ii)
+the growth rate of the magnetic energy density is much faster than the
+turbulent dynamo, iii) the efficient amplification occurs at small scales. The
+analytical prediction for the correlation between the growth timescales with
+pressure anisotropy ratio is confirmed by the numerical simulations. These
+results reinforce the idea that pressure anisotropies - driven naturally in a
+turbulent collisionless medium, e.g. the intergalactic medium -, could
+efficiently amplify the magnetic field in the early Universe
+(post-recombination era), previous to the collapse of the first large-scale
+gravitational structures. This mechanism, though fast for the small scale
+fields ($\sim$kpc scales), is however unable to provide relatively strong
+magnetic fields at large scales. Other mechanisms that were not accounted here
+(e.g., collisional turbulence once instabilities are quenched, velocity shear,
+or gravitationally induced inflows of gas into galaxies and clusters) could
+operate afterwards to build up large scale coherent field structures in the
+long time evolution.",1506.06398v1
+2015-06-23,Breakdown of long-wavelength magnons in cubic antiferromagnets with dipolar forces at small temperature,"Using $1/S$ expansion, we discuss the magnon spectrum of Heisenberg
+antiferromagnet (AF) on a simple cubic lattice with small dipolar interaction
+at small temperature $T\ll T_N$, where $T_N$ is the Neel temperature. Similar
+to 3D and 2D ferromagnets, quantum and thermal fluctuations renormalize greatly
+the bare gapless spectrum leading to a gap $\Delta\sim \omega_0$, where
+$\omega_0$ is the characteristic dipolar energy. This gap is accompanied by
+anisotropic corrections to the free energy which make the cube edges easy
+directions for the staggered magnetization (dipolar anisotropy). In accordance
+with previous results, we find that dipolar forces split the magnon spectrum
+into two branches. This splitting makes possible two types of processes which
+lead to a considerable enhance of the damping compared to the Heisenberg AF: a
+magnon decay into two other magnons and a confluence of two magnons. It is
+found that magnons are well defined quasiparticles in quantum AF. We
+demonstrate however that a small fraction of long-wavelength magnons can be
+overdamped in AFs with $S\gg1$ and in quantum AFs with a single-ion anisotropy
+competing with the dipolar anisotropy. Particular materials are pointed out
+which can be suitable for experimental observation of this long-wavelength
+magnons breakdown that contradicts expectation of the quasiparticle concept.",1506.06989v2
+2015-06-25,The importance of XY anisotropy in Sr2IrO4 revealed by magnetic critical scattering experiments,"The magnetic critical scattering in Sr$_2$IrO$_4$ has been characterized
+using X-ray resonant magnetic scattering (XRMS) both below and above the 3D
+antiferromagnetic ordering temperature, T$_{\text{N}}$. The order parameter
+critical exponent below T$_{\text{N}}$ is found to be \beta=0.195(4), in the
+range of the 2D XYh$_4$ universality class. Over an extended temperature range
+above T$_{\text{N}}$, the amplitude and correlation length of the intrinsic
+critical fluctuations are well described by the 2D Heisenberg model with XY
+anisotropy. This contrasts with an earlier study of the critical scattering
+over a more limited range of temperature which found agreement with the theory
+of the isotropic 2D Heisenberg quantum antiferromagnet, developed to describe
+the critical fluctuations of the conventional Mott insulator La$_2$CuO$_4$ and
+related systems. Our study therefore establishes the importance of XY
+anisotropy in the low-energy effective Hamiltonian of Sr$_2$IrO$_4$, the
+prototypical spin-orbit Mott insulator.",1506.07720v1
+2015-07-15,Self-consistent triaxial models,"We present self-consistent triaxial stellar systems that have analytic
+distribution functions (DFs) expressed in terms of the actions. These provide
+triaxial density profiles with cores or cusps at the centre. They are the first
+self-consistent triaxial models with analytic DFs suitable for modelling giant
+ellipticals and dark haloes. Specifically, we study triaxial models that
+reproduce the Hernquist profile from Williams & Evans (2015), as well as
+flattened isochrones of the form proposed by Binney (2014). We explore the
+kinematics and orbital structure of these models in some detail. The models
+typically become more radially anisotropic on moving outwards, have velocity
+ellipsoids aligned in Cartesian coordinates in the centre and aligned in
+spherical polar coordinates in the outer parts.
+  In projection, the ellipticity of the isophotes and the position angle of the
+major axis of our models generally changes with radius. So, a natural
+application is to elliptical galaxies that exhibit isophote twisting. As
+triaxial St\""ackel models do not show isophote twists, our DFs are the first to
+generate mass density distributions that do exhibit this phenomenon, typically
+with a gradient of $\approx 10^\circ$/effective radius, which is comparable to
+the data.
+  Triaxiality is a natural consequence of models that are susceptible to the
+radial orbit instability. We show how a family of spherical models with
+anisotropy profiles that transition from isotropic at the centre to radially
+anisotropic becomes unstable when the outer anisotropy is made sufficiently
+radial. Models with a larger outer anisotropy can be constructed but are found
+to be triaxial. We argue that the onset of the radial orbit instability can be
+identified with the transition point when adiabatic relaxation yields strongly
+triaxial rather than weakly spherical endpoints.",1507.04129v1
+2015-07-16,"Importance of Fermi Surface Topology for In-Plane Resistivity Anisotropy in Hole- and Electron-Doped Ba(Fe$_{1-x}$TM$_{x}$)$_2$As$_2$ (TM=Cr, Mn and Co)","The in-plane anisotropy of resistivity has been investigated for
+Ba(Fe$_{1-x}$TM$_{x}$)$_2$As$_2$ (TM-Ba122, TM$=$Cr, Mn, and Co) where the
+substitution sites are the same but the doped carriers are different for
+different TM elements. The Hall coefficient measurements indicated that hole
+carriers are effectively doped by Cr substitution but not by Mn substitution.
+It has been found that the resistivity difference $\Delta\rho=\rho_{\rm
+b}-\rho_{\rm a}$ in the antiferromagnetic-orthorhombic (AFO) phase of Cr-Ba122
+is initially positive but it turns to negative with increasing Cr content,
+whereas the positive $\Delta\rho$ monotonically increases with Mn substitution
+in Mn-Ba122. In the paramagnetic-tetragonal phase, $\Delta\rho$ is always
+positive, but it decreases with substitution in Cr-Ba122, in contrast to the
+electron-doped case. These results demonstrate that the resistivity anisotropy
+exhibits electron-hole asymmetry in both AFO and nematic phases and that it
+depends on the Fermi surface topology whether the carrier scattering results in
+a positive or negative $\Delta\rho$.",1507.04519v2
+2015-07-27,Constraints on the Early and Late Integrated Sachs-Wolfe effects from Planck 2015 Cosmic Microwave Background Anisotropies angular power spectra,"The Integrated Sachs-Wolfe (ISW) effect predicts additional anisotropies in
+the Cosmic Microwave Background due to time variation of the gravitational
+potential when the expansion of the universe is not matter dominated. The ISW
+effect is therefore expected in the early universe, due to the presence of
+relativistic particles at recombination, and in the late universe, when dark
+energy starts to dominate the expansion. Deviations from the standard picture
+can be parameterized by $A_{e\text{ISW}}$ and $A_{l\text{ISW}}$, which rescale
+the overall amplitude of the early and late ISW effects. Analyzing the most
+recent CMB temperature spectra from the Planck 2015 release, we detect the
+presence of the early ISW at high significance with $A_{e\mathrm{ISW}} =
+1.06\pm0.04$ at 68% CL and an upper limit for the late ISW of
+$A_{l\mathrm{ISW}} < 1.1$ at 95% CL. The inclusion of the recent polarization
+data from the Planck experiment results in $A_{e\mathrm{ISW}} = 0.999\pm0.028$
+at 68% CL, in better agreement with the value $A_{e\mathrm{ISW}} = 1$ of a
+standard cosmology. When considering the recent detections of the late ISW
+coming from correlations between CMB temperature anisotropies and weak lensing,
+a value of $A_{l\mathrm{ISW}}=0.85\pm0.21$ is predicted at 68% CL, showing a
+$4\sigma$ evidence. We discuss the stability of our result in the case of an
+extra relativistic energy component parametrized by the effective neutrino
+number $N_\mathrm{eff}$ and of a CMB lensing amplitude $A_\mathrm{L}$.",1507.07586v2
+2015-07-28,Structural properties of non-spherical dark halos in Milky Way and Andromeda dwarf spheroidal galaxies,"We investigate the non-spherical density structure of dark halos of the dwarf
+spheroidal (dSph) galaxies in the Milky Way and Andromeda galaxies based on
+revised axisymmetric mass models from our previous work. The models we adopt
+here fully take into account velocity anisotropy of tracer stars confined
+within a flattened dark halo. Applying our models to the available kinematic
+data of the 12 bright dSphs, we find that these galaxies associate with, in
+general, elongated dark halos, even considering the effect of this velocity
+anisotropy of stars. We also find that the best-fit parameters, especially for
+the shapes of dark halos and velocity anisotropy, are susceptible to both the
+availability of velocity data in the outer regions and the effect of the lack
+of sample stars in each spatial bin. Thus, to obtain more realistic limits on
+dark halo structures, we require photometric and kinematic data over much
+larger areas in the dSphs than previously explored. The results obtained from
+the currently available data suggest that the shapes of dark halos in the dSphs
+are more elongated than those of $\Lambda$CDM subhalos. This mismatch needs to
+be solved by theory including baryon components and the associated feedback to
+dark halos as well as by further observational limits in larger areas of dSphs.
+It is also found that more diffuse dark halos may have undergone consecutive
+star formation history, thereby implying that dark-halo structure plays an
+important role in star formation activity.",1507.07620v2
+2015-08-11,Haloes light and dark: dynamical models of the stellar halo and constraints on the mass of the Galaxy,"We develop a flexible set of action-based distribution functions (DFs) for
+stellar haloes. The DFs have five free parameters, controlling the inner and
+outer density slope, break radius, flattening and anisotropy respectively. The
+DFs generate flattened stellar haloes with a rapidly varying logarithmic slope
+in density, as well as a spherically aligned velocity ellipsoid with a long
+axis that points towards the Galactic centre - all attributes possessed by the
+stellar halo of the Milky Way. We use our action-based distribution function to
+model the blue horizontal branch stars extracted from the Sloan Digital Sky
+Survey as stellar halo tracers in a spherical Galactic potential. As the
+selection function is hard to model, we fix the density law from earlier
+studies and solve for the anisotropy and gravitational potential parameters.
+Our best fit model has a velocity anisotropy that becomes more radially
+anisotropic on moving outwards. It changes from $\beta \approx 0.4$ at
+Galactocentric radius of 15 kpc to $\approx 0.7$ at 60 kpc. This is a gentler
+increase than is typically found in simulations of stellar haloes built from
+the mutiple accretion of smaller systems. We find the potential corresponds to
+an almost flat rotation curve with amplitude of $\approx 200$ kms$^{-1}$ at
+these distances. This implies an enclosed mass of $\approx 4.5 \times 10^{11}
+M_\odot$ within a spherical shell of radius 50 kpc.",1508.02584v2
+2015-08-11,Donor Wavefunctions in Si Gauged by STM Images,"The triumph of effective mass theory in describing the energy spectrum of
+dopants does not guarantee that the model wavefunctions will withstand an
+experimental test. Such wavefunctions have recently been probed by scanning
+tunneling spectroscopy, revealing localized patterns of resonantly enhanced
+tunneling currents. We show that the shape of the conducting splotches resemble
+a cut through Kohn-Luttinger (KL) hydrogenic envelopes, which modulate the
+interfering Bloch states of conduction electrons. All the non-monotonic
+features of the current profile are consistent with the charge density
+fluctuations observed between successive {001} atomic planes, including a
+counterintuitive reduction of the symmetry - a heritage of the lowered point
+group symmetry at these planes. A model-independent analysis of the diffraction
+figure constrains the value of the electron wavevector to $k_0 = (0.82 \pm
+0.03)(2\pi/a_{Si})$. Unlike prior measurements, averaged over a sizeable
+density of electrons, this estimate is obtained directly from isolated
+electrons. We further investigate the model-specific anisotropy of the wave
+function envelope, related to the effective mass anisotropy. This anisotropy
+appears in the KL variational wave function envelope as the ratio between Bohr
+radii b=a. We demonstrate that the central cell corrected estimates for this
+ratio are encouragingly accurate, leading to the conclusion that the KL theory
+is a valid model not only for energies but for wavefunctions as well.",1508.02772v1
+2015-08-18,"Determination of the blocking temperature of magnetic nanoparticles: The good, the bad and the ugly","In a magnetization vs. temperature (M vs. T) experiment, the blocking region
+of a magnetic nanoparticle (MNP) assembly is the interval of T values were the
+system begins to respond to an applied magnetic field H when heating the sample
+from the lower reachable temperature. The location of this region is determined
+by the anisotropy energy barrier depending on the applied field H, the volume
+V, the magnetic anisotropy constant K of the MNPs and the observing time of the
+technique. In the general case of a polysized sample, a representative blocking
+temperature value $T_B$ can be estimated from ZFC-FC experiments as a way to
+determine the effective anisotropy constant.
+  In this work, a numerical solved Stoner-Wolfharth two level model with
+thermal agitation is used to simulate ZFC-FC curves of monosized and polysized
+samples and to determine the best method for obtaining a representative $T_B$
+value of polysized samples. The results corroborate a technique based on the T
+derivative of the difference between ZFC and FC curves proposed by Micha et
+al(the good) and demonstrate its relation with two alternative methods: the ZFC
+maximum (the bad) and inflection point (the ugly). The derivative method is
+then applied to experimental data, obtaining the $T_B$ distribution of a
+polysized $Fe_3O_4$ MNP sample suspended in hexane with an excellent agreement
+with TEM characterization.",1508.04413v1
+2015-09-15,Domain-resolved room-temperature magneto-electric coupling in manganite-titanate heterostructures,"We present a model artificial multiferroic system consisting of a
+(011)-oriented ferroelectric Pb(Mg,Nb,Ti)O$_3$ substrate intimately coupled to
+a ferromagnetic (La,Sr)MnO$_3$ film through epitaxial strain and converse
+piezoelectric effects. Electric field pulse sequences of less than 6 kV/cm were
+shown to induce large reversible and bistable remanent strains in the manganite
+film. Magnetic hysteresis loops demonstrate that the changes in strain states
+result in significant changes in magnetic anisotropy from a highly anisotropic
+two-fold magnetic symmetry to a more isotropic one. Such changes in magnetic
+anisotropy are reversible upon multiple cycles and are stable at zero applied
+electric field, and are accompanied by large changes in resistivity. We
+directly image the change between the two-fold and isotropic magnetic
+configurations at the scale of a single ferromagnetic domain using X-ray
+photoemission electron microscopy as a function of applied electric field
+pulses. Imaging the domain reversal process as a function of electric field
+shows that the energy barrier for magnetization reversal is drastically
+lowered, by up to 70% as determined from free energy calculations, through the
+anisotropic strain change generated by the ferroelectric substrate. Thus, an
+electric field pulse can be used to 'set' and 'reset' the magnetic anisotropy
+orientation and resistive state in the film, as well as lowering the coercive
+field required to reverse magnetization, showing a promising route towards
+electric-field manipulation of multifunctional nanostructures at room
+temperature.",1509.04775v1
+2015-09-23,Anisotropic hyperfine interactions in FeP studied by 57Fe Mossbauer spectroscopy and 31P NMR,"We report results of 57Fe Mossbauer and 31P NMR studies of a phosphide FeP
+powder sample performed in a wide temperature range including the point (TN ~
+120 K) of magnetic phase transitions. The 57Fe Mossbauer spectra at low
+temperatures T < TN consist of very diffuse Zeeman pattern with line
+broadenings and sizeable spectral asymmetry. It was shown that the change of
+the observed spectral shape is consistent with the transition into the space
+modulated helicoidal magnetic structure. Analysis of the experimental spectra
+was carried out assuming the anisotropy of the magnetic hyperfine field Hhf at
+the 57Fe nuclei when the Fe3+ magnetic moment rotates with respect to the
+principal axis of the electric field gradient (EFG) tensor. The obtained large
+temperature independent anharmonicity parameter m ~ 0.96 of the helicoidal spin
+structure results from easy-axis anisotropy in the plane of the iron spin
+rotation. It was assumed that the very low maximal value of Hhf(11K) ~ 36 kOe
+and its high anisotropy delta_Hanis(11K) ~ 30 kOe can be attributed to the
+stabilization of iron cations in the low-spin state (SFe = 1/2). The 31P NMR
+measurements demonstrate an extremely broad linewidth reflecting the spatial
+distribution of the transferred internal magnetic fields of the Fe3+ ions onto
+P sites in the magnetically ordered state.",1509.06953v2
+2015-10-07,Large scale CMB anomalies from thawing cosmic strings,"Cosmic strings formed during inflation are expected to be either diluted over
+super-Hubble distances, i.e., invisible today, or to have crossed our past
+light cone very recently. We discuss the latter situation in which a few
+strings imprint their signature in the Cosmic Microwave Background (CMB)
+Anisotropies after recombination. Being almost frozen in the Hubble flow, these
+strings are quasi static and evade almost all of the previously derived
+constraints on their tension while being able to source large scale
+anisotropies in the CMB sky. Using a local variance estimator on thousand of
+numerically simulated Nambu-Goto all sky maps, we compute the expected signal
+and show that it can mimic a dipole modulation at large angular scales while
+being negligible at small angles. Interestingly, such a scenario generically
+produces one cold spot from the thawing of a cosmic string loop. Mixed with
+anisotropies of inflationary origin, we find that a few strings of tension GU =
+O(1) x 10^(-6) match the amplitude of the dipole modulation reported in the
+Planck satellite measurements and could be at the origin of other large scale
+anomalies.",1510.01916v2
+2015-11-14,Anisotropies of gravitational-wave standard sirens as a new cosmological probe without redshift information,"Gravitational waves (GWs) from compact binary stars at cosmological distances
+are promising and powerful cosmological probes, referred to as the GW standard
+sirens. With future GW detectors, we will be able to precisely measure source
+luminosity distances out to a redshift $z\sim5$. To extract cosmological
+information, previously proposed cosmological studies using the GW standard
+sirens rely on source redshift information obtained through an extensive
+electromagnetic follow-up campaign. However, the redshift identification is
+typically time consuming and rather challenging. Here, we propose a novel
+method for cosmology with the GW standard sirens free from the redshift
+measurements. Utilizing the anisotropies of the number density and luminosity
+distances of compact binaries originated from the large-scale structure, we
+show that, once GW observations will be well established in the future, (i)
+these anisotropies can be measured even at very high redshifts ($z\geq 2$),
+where the identification of the electromagnetic counterpart is difficult, (ii)
+the expected constraints on the primordial non-Gaussianity with the Einstein
+Telescope would be comparable to or even better than the other large-scale
+structure probes at the same epoch, and (iii) the cross-correlation with other
+cosmological observations is found to have high-statistical significance,
+providing additional cosmological information at very high redshifts.",1511.04638v2
+2015-11-18,Nonadiabatic bounce and an inflationary phase in the quantum mixmaster universe,"Following our previous paper, Bergeron et al, Smooth quantum dynamics of the
+mixmaster universe, Phys. Rev. D 92, 061302(R) (2015), concerning the
+quantization of the vacuum Bianchi IX model and the Born-Huang-Oppenheimer
+framework, we present a further analysis of the dynamical properties of the
+model. Consistently with the deep quantum regime, we implement the harmonic
+approximation of the anisotropy potential. We thus obtain manageable dynamical
+equations. We study the quantum anisotropic oscillations during the bouncing
+phase of the universe. Neglecting the backreaction from transitions between
+quantum anisotropy states we obtain analytical results. In particular, we
+identify a parameter which is associated with dynamical properties of the
+quantum model and describes a sort of phase transition. Once the parameter
+exceeds its critical value, the Born-Huang-Oppenheimer approximation breaks
+down. The application of the present result to a simple model of the Universe
+indicates that the parameter indeed exceeds its critical value and that there
+takes place a huge production of anisotropy at the bounce. This in turn must
+lead to a sustained phase of accelerated expansion, an inflationary phase. The
+quantitative inclusion of backreaction shall be examined in a follow-up paper
+based on the vibronic approach.",1511.05790v2
+2016-01-06,Galaxy structure from multiple tracers: II. M87 from parsec to megaparsec scales,"Following a number of conflicting studies of M87's mass profile, we undertake
+a dynamical analysis of multiple tracer populations to constrain its mass over
+a large radius range. We combine stellar kinematics in the central regions with
+the dynamics of 612 globular clusters out to 200 kpc and satellite galaxies
+extending to scales comparable with the virial radius. Using a spherical Jeans
+analysis, we are able to disentangle the mass contributions from the dark and
+baryonic components and set constraints on the structure of each. Assuming
+isotropy, we explore four different models for the dark matter halo and find
+that a centrally-cored dark matter distribution is preferred. We infer a
+stellar mass-to-light ratio $\Upsilon_{\star,v} = 6.9 \pm 0.1$ -- consistent
+with a Salpeter-like IMF -- and a core radius $r_c = 67 \pm 20$ kpc. We then
+introduce anisotropy and find that, while the halo remains clearly cored, the
+radial stellar anisotropy has a strong impact on both $\Upsilon_{\star,v}$ and
+the core's radius; here we find $\Upsilon_{\star,v} = 3.50_{-0.36}^{+0.32}$ --
+consistent with a Chabrier-like IMF -- and $r_c = 19.00_{-8.34}^{+8.38}$ kpc.
+Thus the presence of a core at the centre of the dark halo is robust against
+anisotropy assumptions, while the stellar mass and core size are not. We are
+able to reconcile previously discrepant studies by showing that modelling the
+globular cluster data alone leads to the very different inference of a
+super-NFW cusp, thus highlighting the value of multiple-population modelling,
+and we point to the possible role of M87's AGN and the cluster environment in
+forming the central dark matter core.",1601.01323v1
+2016-01-23,Spectral imaging of galaxy clusters with Planck,"The Sunyaev-Zeldovich (SZ) effect is a promising tool for detecting the
+presence of hot gas out to the galaxy cluster peripheries. We developed a
+spectral imaging algorithm dedicated to the SZ observations of nearby galaxy
+clusters with Planck, with the aim of revealing gas density anisotropies
+related to the filamentary accretion of materials, or pressure discontinuities
+induced by the propagation of shock fronts. To optimize an unavoidable
+trade-off between angular resolution and precision of the SZ flux measurements,
+the algorithm performs a multiscale analysis of the SZ maps as well as of other
+extended components, such as the cosmic microwave background (CMB) anisotropies
+and the Galactic thermal dust. The demixing of the SZ signal is tackled through
+kernel weighted likelihood maximizations. The CMB anisotropies are further
+analyzed through a wavelet analysis, while the Galactic foregrounds and SZ maps
+are analyzed via a curvelet analysis that best preserves their anisotropic
+details. The algorithm performance has been tested against mock observations of
+galaxy clusters obtained by simulating the Planck High Frequency Instrument and
+by pointing a few characteristic positions in the sky. These tests suggest that
+Planck should easily allow us to detect filaments in the cluster peripheries
+and detect large-scale shocks in colliding galaxy clusters that feature
+favorable geometry.",1601.06323v1
+2016-02-01,Derivation of anisotropic dissipative fluid dynamics from the Boltzmann equation,"Fluid-dynamical equations of motion can be derived from the Boltzmann
+equation in terms of an expansion around a single-particle distribution
+function which is in local thermodynamical equilibrium, i.e., isotropic in
+momentum space in the rest frame of a fluid element. However, in situations
+where the single-particle distribution function is highly anisotropic in
+momentum space, such as the initial stage of heavy-ion collisions at
+relativistic energies, such an expansion is bound to break down. Nevertheless,
+one can still derive a fluid-dynamical theory, called anisotropic dissipative
+fluid dynamics, in terms of an expansion around a single-particle distribution
+function, $\hat{f}_{0\bf k}$, which incorporates (at least parts of) the
+momentum anisotropy via a suitable parametrization. We construct such an
+expansion in terms of polynomials in energy and momentum in the direction of
+the anisotropy and of irreducible tensors in the two-dimensional momentum
+subspace orthogonal to both the fluid velocity and the direction of the
+anisotropy. From the Boltzmann equation we then derive the set of equations of
+motion for the irreducible moments of the deviation of the single-particle
+distribution function from $\hat{f}_{0\bf k}$. Truncating this set via the
+14-moment approximation, we obtain the equations of motion of anisotropic
+dissipative fluid dynamics.",1602.00573v2
+2016-02-16,Theoretical study on the anisotropic electronic structure of antiferromagnetic BaFe$_2$As$_2$ and Co-doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ seen by angle-resolved photoemission,"By means of one-step model calculations the strong in-plane anisotropy seen
+in angle-resolved photoemission of the well-known iron pnictide prototype
+compounds BaFe$_2$As$_2$ and Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ in their
+low-temperature antiferromagnetic phases is investigated. The
+fully-relativistic calculations are based on the Korringa-Kohn-Rostoker-Green
+function approach combined with the coherent potential approximation alloy
+theory to account for the disorder induced by Co substitution on Fe sites in a
+reliable way. The results of the calculations can be compared directly to
+experimental spectra of detwinned single crystals. One finds very good
+agreement with experiment and can reveal all features of the electronic
+structure contributing to the in-plane anisotropy. In particular the local
+density approximation can capture most of the correlation effects for the
+investigated system without the need for more advanced techniques. In addition,
+the evolution of the anisotropy for increasing Co concentration $x$ in
+Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ can be tracked almost continuously. The results
+are also used to discuss surface effects and it is possible to identify clear
+signatures to conclude about different types of surface termination.",1602.05027v1
+2016-02-24,Effects of low anisotropy on interacting holographic and new agegraphic scalar fields models of dark energy,"A spatially homogeneous and anisotropic Bianchi type I universe is studied
+with the interacting holographic and new agegraphic scalar fields models of
+dark energy.
+  Given, the framework of the anisotropic model, both the dynamics and
+potential of these scalar field models according to the evolutionary behavior
+of both dark energy models are reconstructed. We also investigate the
+cosmological evolution of interacting dark energy models, and compare it with
+observational data and schematic diagram.
+  In order to do so, we focus on observational determinations of the expansion
+history $H(z)$. Next, we evaluate effects of anisotropy on various topics, such
+as evolution of the growth of perturbations in the linear regime, statefinder
+diagnostic, Sandage-Loeb (SL) test and distance modulus from holographic and
+new agegraphic dark energy models and compare the results with standard FRW and
+$\Lambda$CDM and $w$CDM models.
+  Our numerical result show the effects of the interaction and anisotropy on
+the evolutionary behavior the new agegraphic scalar field models",1602.07683v6
+2016-03-02,Incommensurate--commensurate transitions in the mono-axial chiral helimagnet driven by the magnetic field,"The zero temperature phase diagram of the mono-axial chiral helimagnet in the
+magnetic field plane formed by the components parallel and perpendicular to the
+helical axis is thoroughly analyzed. The nature of the transition to the
+commensurate state depends on the angle between the field and the helical axis.
+For field directions close to the directions parallel or perpendicular to the
+helical axis the transition is continuous, while for intermediate angles the
+transition is discontinuous and the incommensurate and commensurate states
+coexist on the transition line. The continuous and discontinuous transition
+lines are separated by two tricritical points with specific singular behaviour.
+The location of the continuous and discontinuous lines and of the tricritical
+points depend strongly on the easy-plane anisotropy, the effect of which is
+analyzed. For large anisotropy the conical approximation locates the transition
+line very accurately, although it does not predict the continuous transitions
+nor the tricitical behaviour. It is shown that for large anisotropy, as in
+CrNb3S6, the form of the transition line is universal, that is, independent of
+the sample, and obeys a simple equation. The position of the tricritical
+points, which is not universal, is theoretically estimated for a sample of
+CrNb3S6",1603.00755v1
+2016-03-09,Primordial Magnetic Field Via Weibel Instability In The Quark Gluon Plasma Phase,"The origin of the observed large scale magnetic fields in the Universe is a
+mystery. The seed of these magnetic fields has been attributed to physical
+process in the early universe. In this work we provide a mechanism for the
+generation of a primordial magnetic field in the early universe via the Weibel
+instability in the quark gluon plasma. The Weibel instability occurs in the
+plasma if there is an anisotropy in the particle distribution function of the
+particles. In early universe, the velocity anisotropy required for Weibel
+instability to operate is generated in the quark gluon plasma by the collapse
+of closed $Z(3)$ domain walls that arise in the deconfined phase of the QCD
+(above $T\sim 200$ MeV). Such large domains can arise in the context of certain
+low energy scale inflationary models. The closed domains undergo supersonic
+collapse and the velocity anisotropy is generated in the shocks produced in the
+wake of the collapsing domain walls. This results in a two stream Weibel
+instability in the ultra-relativistic quark gluon plasma. The instability in
+turn generates strong magnetic fields in the plasma. We find that the field
+strengths generated can be comparable to the equipartition energy density at
+the QCD scale which is of the order of $10^{18}$ G.",1603.02852v2
+2016-03-14,Rotational symmetry breaking in the topological superconductor Sr$_x$Bi$_2$Se$_3$ probed by upper-critical field experiments,"Recently it was demonstrated that Sr intercalation provides a new route to
+induce superconductivity in the topological insulator Bi$_2$Se$_3$. Topological
+superconductors are predicted to be unconventional, with mixed even and odd
+parity Cooper pairs states. An adequate probe to test for unconventional
+superconductivity is the upper critical field, $B_{c2}$. For a standard BCS
+layered superconductor $B_{c2}$ shows an anisotropy when the magnetic field is
+applied parallel and perpendicular to the layers, but is isotropic when the
+field is rotated in the plane of the layers. Here we report measurements of the
+upper critical field of superconducting Sr$_x$Bi$_2$Se$_3$ crystals ($T_c =
+3.0$~K). Surprisingly, field-angle dependent magnetotransport measurements
+reveal a large anisotropy of $B_{c2}$ when the magnet field is rotated in the
+basal plane. The large two-fold anisotropy, while six-fold is anticipated,
+cannot be explained with the Ginzburg-Landau anisotropic effective mass model
+or flux flow induced by the Lorentz force. The rotational symmetry breaking of
+$B_{c2}$ indicates unconventional superconductivity with an odd-parity
+polarized triplet Cooper pair state ($\Delta_4$-pairing) recently proposed for
+rhombohedral topological superconductors, or might have a structural nature,
+such as self-organized stripe ordering of Sr atoms.",1603.04197v1
+2016-03-21,NMR signal for particles diffusing under potentials: From path integrals and numerical methods to a new model of diffusion anisotropy,"We study the influence of diffusion on NMR experiments when the molecules
+undergo random motion under the influence of a force field, and place special
+emphasis on parabolic (Hookean) potentials. To this end, the problem is studied
+using path integral methods. Explicit relationships are derived for commonly
+employed gradient waveforms involving pulsed and oscillating gradients. The
+Bloch-Torrey equation, describing the temporal evolution of magnetization, is
+modified by incorporating potentials. A general solution to this equation is
+obtained for the case of parabolic potential by adopting the multiple
+correlation function (MCF) formalism, which has been used in the past to
+quantify the effects of restricted diffusion. Both analytical and MCF results
+were found to be in agreement with random walk simulations. A multi-dimensional
+formulation of the problem is introduced that leads to a new characterization
+of diffusion anisotropy. Unlike for the case of traditional methods that employ
+a diffusion tensor, anisotropy originates from the tensorial force constant,
+and bulk diffusivity is retained in the formulation. Our findings suggest that
+some features of the NMR signal that have traditionally been attributed to
+restricted diffusion are accommodated by the Hookean model. Under certain
+conditions, the formalism can be envisioned to provide a viable approximation
+to the mathematically more challenging restricted diffusion problems.",1603.06373v1
+2016-04-06,Universal behavior of dense clusters of magnetic nanoparticles,"A detailed numerical simulation of quasistatic hysteresis loops of dense
+clusters of interacting magnetic nanoparticles is carried out. Both clusters of
+magnetically soft and magnetically hard nanoparticles are considered. The
+clusters are characterized by an average particle diameter D, the cluster
+radius Rc, the particle saturation magnetization Ms, and the uniaxial
+anisotropy constant K. The number of particles in the cluster varies between Np
+= 30 - 120. The particle centers are randomly distributed within the cluster,
+their easy anisotropy axes being randomly oriented. It is shown that a rare
+assembly of identical random clusters of magnetic nanoparticles can be
+characterized by two dimensionless parameters: 1) the relative strength of
+magneto-dipole interaction, K/Ms^2, and the average particle concentration
+within the cluster, {\eta} = VNp/Vc. Here V is the nanoparticle volume, and Vc
+is the volume of the cluster, respectively. In the strong interaction limit,
+Ms*{\eta}/Ha >> 1, where Ha = 2K/Ms is the anisotropy field, the ultimate
+hysteresis loops of dilute assemblies of clusters have been constructed. In the
+variables (M/Ms, H/Ms) these hysteresis loops depend only on the particle
+volume fraction {\eta}. In the weak interaction limit, Ms*{\eta}/Ha << 1, the
+assembly hysteresis loops in the variables (M/Ms, H/Ha) are close to the
+standard Stoner-Wohlfarth hysteresis loop.",1604.01705v1
+2016-04-18,Anisotropic magnetization relaxation in ferromagnetic multilayers with variable interlayer exchange coupling,"The FMR linewidth and its anisotropy in F$_1$/f/F$_2$/AF multilayers, where
+spacer f has a low Curie point compared to the strongly ferromagnetic F$_1$ and
+F$_2$, is investigated. The role of the interlayer exchange coupling in
+magnetization relaxation is determined experimentally by varying the thickness
+of the spacer. It is shown that stronger interlayer coupling via thinner
+spacers enhances the microwave energy exchange between the outer ferromagnetic
+layers, with the magnetization of F$_2$ exchange-dragged by the resonance
+precession in F$_1$. A weaker mirror effect is also observed: the magnetization
+of F$_1$ can be exchange-dragged by the precession in F$_2$, which leads to
+anti-damping and narrower FMR linewidths. A theory is developed to model the
+measured data, which allows separating various contributions to the magnetic
+relaxation in the system. Key physical parameters, such as the interlayer
+coupling constant, in-plane anisotropy of the FMR linewidth, dispersion of the
+magnetic anisotropy fields are quantified. These results should be useful for
+designing high-speed magnetic nanodevices based on thermally-assisted
+switching.",1604.05145v1
+2016-04-19,Firehose constraints for the solar wind suprathermal electrons,"The indefinite increase of temperature predicted by the solar wind expansion
+in the direction parallel to the interplanetary magnetic field is already
+notorious for not being confirmed by the observations. In hot and dilute
+plasmas from space particle-particle collisions are not efficient in
+constraining large deviations from isotropy, but the resulting firehose
+instability provides in this case plausible limitations for the temperature
+anisotropy of the thermal (core) populations of both the electron and proton
+species. The present paper takes into discussion the suprathermal (halo)
+electrons, which are ubiquitous in the solar wind. Less dense but hotter than
+the core, suprathermals may be highly anisotropic and susceptible to the
+firehose instability. The main features of the instability are here derived
+from a first-order theory for conditions specific to the suprathermal electrons
+in the solar wind and terrestrial magnetospheres. Unveiled here, new regimes of
+the electron firehose instability may be exclusively controlled by the
+suprathermals. The instability is found to be systematically stimulated by the
+suprathermal electrons, with thresholds that approach the limits of the
+temperature anisotropy reported by the observations. These results represent
+new and valuable evidences for the implication of the firehose instability in
+the relaxation of the temperature anisotropy in space plasmas.",1604.05628v1
+2016-04-20,Dipolar matter-wave solitons in two-dimensional anisotropic discrete lattices,"We numerically demonstrate two-dimensional (2D) matter-wave solitons in the
+disk-shaped dipolar Bose-Einstein condensates (BECs) trapped in strongly
+anisotropic optical lattices (OLs) in a disk's plane. The considered OLs are
+square lattices which can be formed by interfering two pairs of plane waves
+with different intensities. The hopping rates of the condensates between two
+adjacent lattices in the orthogonal directions are different, which gives rise
+to a linearly anisotropic system. We find that when the polarized orientation
+of the dipoles is parallel to disk's plane with the same direction, the
+combined effects of the linearly anisotropy and the nonlocal nonlinear
+anisotropy strongly influence the formations, as well as the dynamics of the
+lattice solitons. Particularly, the isotropy-pattern solitons (IPSs) are found
+when these combined effects reach a balance. Motion, collision and rotation of
+the IPSs are also studied in detail by means of systematic simulations. We
+further find that these IPSs can move freely in the 2D anisotropic discrete
+system, hence giving rise to an anisotropic effective mass. Four types of
+collisions between the IPSs are identified. By rotating an external magnetic
+field up to a critical angular velocity, the IPSs can still remain localized
+and play as a breather. Finally, the influences from the combined effects
+between the linear and the nonlocal nonlinear anisotropy with consideration of
+the contact/local nonlinearity are discussed too.",1604.05798v2
+2016-04-25,Origin of the mass splitting of azimuthal anisotropies in a multi-phase transport model,"Both hydrodynamics-based models and a multi-phase transport (AMPT) model can
+reproduce the mass splitting of azimuthal anisotropy ($v_n$) at low transverse
+momentum ($p_{\perp}$) as observed in heavy ion collisions. In the AMPT model,
+however, $v_n$ is mainly generated by the parton escape mechanism, not by the
+hydrodynamic flow. In this study we provide detailed results on the mass
+splitting of $v_n$ in this transport model, including $v_2$ and $v_3$ of
+various hadron species in d+Au and Au+Au collisions at the Relativistic Heavy
+Ion Collider and p+Pb collisions at the Large Hadron Collider. We show that the
+mass splitting of hadron $v_2$ and $v_3$ in AMPT first arises from the
+kinematics in the quark coalescence hadronization process, and then, more
+dominantly, comes from hadronic rescatterings, even though the contribution
+from the latter to the overall charged hadron $v_n$ is small. We further show
+that there is no qualitative difference between heavy ion collisions and
+small-system collisions or between elliptic ($v_2$) and triangular ($v_3$)
+anisotropies. Our studies thus demonstrate that the mass splitting of $v_2$ and
+$v_3$ at low-$p_{\perp}$ is not a unique signature of hydrodynamic collective
+flow but can be the interplay of several physics effects.",1604.07387v3
+2016-05-04,The Influence of Temperature Anisotropies in Controlling the Development of Magnetospheric Substorms,"Ion anisotropies can affect a host of processes within the magnetosphere,
+from modifying the growth rate of various instabilities to the energization and
+mass transport within the magnetosphere. Global multi-fluid simulations using a
+full treatment of the pressure tensor are used to evaluate the influence of
+temperature anisotropies on the magnetospheric dynamics for an idealized
+substorm. The simulations are able to resolve the development of conics over
+the polar cap which eventually turn into beams in the lobes. Entry of this
+plasma, particularly heavy ions with high Tparallel, leads to a faster
+reconnection rate, additional turbulence within the reconnection region, and
+the substorm onset time occurs approximately 5 min earlier relative to
+isotropic simulations. The anisotropic treatment yields much more intense
+auroral currents on the nightside associated with onset and a faster expansion
+phase of the substorm. The plasma entering into the current sheet experiences
+stronger heating in the anisotropic simulations, which increases plasma
+transport into the equatorial dayside. Hence, the convection of the
+plasmasphere towards the dayside magnetosphere during the growth phase is
+accompanied by a relative increase in Tparallel. This leads to a very distinct
+temperature profile on the dayside. The injection of the energetic particles
+from the substorm leads to an overall increase Tperpendicular on the dayside,
+but only O+ reaches sufficient energies for the bulk of these ions to be able
+to cross noon local time during the expansion phase to participate in the
+formation of symmetric ring current. The net effect from these processes is to
+decrease the cross-polar cap potential, modify the timing of the development of
+reconnection and the development of the auroral currents and enhance the
+injection of energetic particles into the inner magnetosphere.",1605.01399v1
+2016-05-07,Giant interfacial perpendicular magnetic anisotropy in MgO/CoFe/capping layer structures,"Magnetic tunnel junction (MTJ) based on CoFeB/MgO/CoFeB structures is of
+great interest due to its application in the spin-transfer-torque magnetic
+random access memory (STT-MRAM). Large interfacial perpendicular magnetic
+anisotropy (PMA) is required to achieve high thermal stability. Here we use
+first-principles calculations to investigate the magnetic anisotropy energy
+(MAE) of MgO/CoFe/capping layer structures, where the capping materials include
+5d metals Hf, Ta, Re, Os, Ir, Pt, Au and 6p metals Tl, Pb, Bi. We demonstrate
+that it is feasible to enhance PMA by using proper capping materials.
+Relatively large PMA is found in the structures with capping materials of Hf,
+Ta, Os, Ir and Pb. More importantly, the MgO/CoFe/Bi structure gives rise to
+giant PMA (6.09 mJ/m2), which is about three times larger than that of the
+MgO/CoFe/Ta structure. The origin of the MAE is elucidated by examining the
+contributions to MAE from each atomic layer and orbital. These findings provide
+a comprehensive understanding of the PMA and point towards the possibility to
+achieve advanced-node STT-MRAM with high thermal stability.",1605.02247v5
+2016-05-17,Classical Monte Carlo study for antiferro quadrupole orders in a diamond lattice,"We investigate antiferro quadrupole orders in a diamond lattice under
+magnetic fields by Monte Carlo simulations for two types of classical effective
+models. One is an XY model with Z_3 anisotropy, and the other is a
+two-component phi^4 model with a third-order anisotropy. We confirm that the
+universality class of the zero-field transition is that for the
+three-dimensional XY model. Magnetic field corresponds to a Z_3 field in the
+effective model, and under this field, we find that collinear and canted
+antiferro-quadrupole orders compete. Each phase is characterized by symmetry
+breaking in the sector of (sublattice Z_2)x(reflection Z_2 for the order
+parameter). When Z_3 anisotropy and magnetic field vary, it turns out that this
+system is a good playground for various multicritical points; bicritical and
+tetracritical points emerge in a finite field. Another important finding is
+about the scaling of parasitic ferro quadrupole order at the zero-field
+critical point. This is the secondary order parameter induced by the primary
+antiferro order, and its critical exponent beta'=0.815 clearly differs from the
+expected value that is twice the value for the primary order parameter. The
+corresponding correlation length exponent is also different, nu'=0.597(12). We
+also discuss relation of the present effective quadrupole models with the
+3-state Potts model as well as implication to undertanding of orbital orders in
+Pr-based 1-2-20 compounds.",1605.05175v2
+2016-05-18,Structural and magnetic properties of FeMn$_x$ ($x=$1...6) chains supported on Cu$_2$N / Cu (100),"Heterogeneous atomic magnetic chains are built by atom manipulation on a
+Cu$_2$N/Cu (100) substrate. Their magnetic properties are studied and
+rationalized by a combined scanning tunneling microscopy (STM) and density
+functional theory (DFT) work completed by model Hamiltonian studies. The chains
+are built using Fe and Mn atoms ontop of the Cu atoms along the N rows of the
+Cu$_2$N surface. Here, we present results for FeMn$_x$ ($x$=1...6) chains
+emphasizing the evolution of the geometrical, electronic, and magnetic
+properties with chain size. By fitting our results to a Heisenberg Hamiltonian
+we have studied the exchange-coupling matrix elements $J$ for different chains.
+For the shorter chains, $x \leq 2$, we have included spin-orbit effects in the
+DFT calculations, extracting the magnetic anisotropy energy. Our results are
+also fitted to a simple anisotropic spin Hamiltonian and we have extracted
+values for the longitudinal-anisotropy $D$ and transversal-anisotropy $E$
+constants. These parameters together with the values for $J$ allow us to
+compute the magnetic excitation energies of the system and to compare them with
+the experimental data.",1605.05464v1
+2016-05-19,Extreme-value statistics from Lagrangian convex hull analysis for homogeneous turbulent Boussinesq convection and MHD convection,"We investigate the utility of the convex hull of many Lagrangian tracers to
+analyze transport properties of turbulent flows with different anisotropy. In
+direct numerical simulations of statistically homogeneous and stationary
+Navier-Stokes turbulence, neutral fluid Boussinesq convection, and MHD
+Boussinesq convection a comparison with Lagrangian pair dispersion shows that
+convex hull statistics capture the asymptotic dispersive behavior of a large
+group of passive tracer particles. Moreover, convex hull analysis provides
+additional information on the sub-ensemble of tracers that on average disperse
+most efficiently in the form of extreme value statistics and flow anisotropy
+via the geometric properties of the convex hulls. We use the convex hull
+surface geometry to examine the anisotropy that occurs in turbulent convection.
+Applying extreme value theory, we show that the maximal square extensions of
+convex hull vertices are well described by a classic extreme value
+distribution, the Gumbel distribution. During turbulent convection,
+intermittent convective plumes grow and accelerate the dispersion of Lagrangian
+tracers. Convex hull analysis yields information that supplements standard
+Lagrangian analysis of coherent turbulent structures and their influence on the
+global statistics of the flow.",1605.05983v4
+2016-05-21,Mott Transitions and Staggered Orders in the Three-component Fermionic System: Variational Cluster Approach,"The variational cluster approximation is used to study the ground-state
+properties and single-particle spectra of the three-component fermionic Hubbard
+model defined on the two-dimensional square lattice at half filling. First, we
+show that either a paired Mott state or color-selective Mott state is realized
+in the paramagnetic system, depending on the anisotropy in the interaction
+strengths, except around the SU(3) symmetric point, where a paramagnetic
+metallic state is maintained. Then, by introducing Weiss fields to observe
+spontaneous symmetry breakings, we show that either a color-density-wave state
+or color-selective antiferromagnetic state is realized depending on the
+interaction anisotropy and that the first-order phase transition between these
+two states occurs at the SU(3) point. We moreover show that these staggered
+orders originate from the gain in potential energy (or Slater mechanism) near
+the SU(3) point but originate from the gain in kinetic energy (or Mott
+mechanism) when the interaction anisotropy is strong. The staggered orders near
+the SU(3) point disappear when the next-nearest-neighbor hopping parameters are
+introduced, indicating that these orders are fragile, protected only by the
+Fermi surface nesting.",1605.06648v1
+2016-05-23,Collisionless Isotropization of the Solar-Wind Protons by Compressive Fluctuations and Plasma Instabilities,"Compressive fluctuations are a minor yet significant component of
+astrophysical plasma turbulence. In the solar wind, long-wavelength compressive
+slow-mode fluctuations lead to changes in $\beta_{\parallel \mathrm p}\equiv
+8\pi n_{\mathrm p}k_{\mathrm B}T_{\parallel \mathrm p}/B^2$ and in $R_{\mathrm
+p}\equiv T_{\perp \mathrm p}/T_{\parallel \mathrm p}$, where $T_{\perp \mathrm
+p}$ and $T_{\parallel \mathrm p}$ are the perpendicular and parallel
+temperatures of the protons, $B$ is the magnetic field strength, and
+$n_{\mathrm p}$ is the proton density. If the amplitude of the compressive
+fluctuations is large enough, $R_{\mathrm p}$ crosses one or more instability
+thresholds for anisotropy-driven microinstabilities. The enhanced field
+fluctuations from these microinstabilities scatter the protons so as to reduce
+the anisotropy of the pressure tensor. We propose that this scattering drives
+the average value of $R_{\mathrm p}$ away from the marginal stability boundary
+until the fluctuating value of $R_{\mathrm p}$ stops crossing the boundary. We
+model this ""fluctuating-anisotropy effect"" using linear Vlasov--Maxwell theory
+to describe the large-scale compressive fluctuations. We argue that this effect
+can explain why, in the nearly collisionless solar wind, the average value of
+$R_{\mathrm p}$ is close to unity.",1605.07143v2
+2016-05-30,Suppressed magnetic circular dichroism and valley-selective magneto-absorption due to the effective mass anisotropy in bismuth,"We have measured the far-infrared reflectivity and Kerr angle spectra on a
+high-quality crystal of pure semimetallic bismuth as a function of magnetic
+field, from which we extract the conductivity for left- and right handed
+circular polarisations. The high spectral resolution allows us to separate the
+intraband Landau level transitions for electrons and holes. The hole transition
+exhibits 100% magnetic circular dichroism, it appears only for one polarisation
+as expected for a circular cyclotron orbit. However the dichroism for electron
+transitions is reduced to only $13\pm 1$%, which is quantitatively explained by
+the large effective mass anisotropy of the electron pockets of the Fermi
+surface. This observation is a signature of the mismatch between the metric
+experienced by the photons and the electrons. It allows for a contactless
+measurement of the effective mass anisotropy and provides a direction towards
+valley polarised magneto-optical pumping with elliptically polarised light.",1605.09224v2
+2016-06-16,"Magnetic Properties from the Viewpoints of Electronic Hamiltonian: Spin Exchange Parameters, Spin Orientation and Spin-Half Misconception","In this chapter we review the quantitative and qualitative aspects of
+describing the properties of magnetic solids on the basis of electronic
+Hamiltonian. We show that a spin Hamiltonian approach becomes consistent with
+an electronic Hamiltonian approach if the spin lattice and its associated spin
+exchange parameters, to be used for the spin Hamiltonian, are determined by the
+energy-mapping analysis based on DFT calculations. The preferred spin
+orientation (i.e., the magnetic anisotropy) of a magnetic ion is not predicted
+by a spin Hamiltonian because it does not include the orbital degree of freedom
+explicitly. In contrast, the magnetic anisotropy is readily predicted by
+electronic structure theories employing both orbital and spin degrees of
+freedom, if one takes into consideration the spin-orbit coupling (SOC). It was
+shown that the preferred spin orientation of a magnetic ion can be predicted
+and understood in terms of the HOMO-LUMO interactions of the magnetic ion by
+taking SOC as perturbation. A spin Hamiltonian gives rise to the spin-half
+misconception, namely, the blind belief that spin-half magnetic ions do not
+possess magnetic anisotropy that arise from SOC. This misconception is a direct
+consequence from the limitedness of a spin Hamiltonian that it lacks the
+orbital degree of freedom. We show that the magnetic properties of 5d ion
+oxides are better explained by the LS-coupling than by the jj-coupling scheme
+of SOC, that the spin-orbital entanglement of 5d ions is not as strong as has
+been assumed.",1606.05220v1
+2016-06-21,Is there evidence for anomalous dipole anisotropy in the large-scale structure?,"We probe the anisotropy of the large-scale structure (LSS) with the
+WISE-2MASS catalogue. This analysis is performed by a directional comparison of
+the galaxy number counts through the entire celestial sphere once systematic
+effects, such as star-galaxy separation and foregrounds contamination, are
+properly taken into account. We find a maximal hemispherical asymmetry whose
+dipolar component is $A = 0.0507 \pm 0.0014$ toward the $(l,b) =
+(323^{\circ},-5^{\circ})$ direction, whose result is consistent with previous
+estimations of our proper motion in low and intermediate redshifts, as those
+carried out with Type Ia Supernovae and similar LSS catalogues. Furthermore,
+this dipole amplitude is statistically consistent ($p$-value = $0.061$) with
+mock catalogues simulated according to the expected $\Lambda$CDM matter density
+fluctuations, in addition to observational biases such as the incomplete
+celestial coverage and anisotropic sky exposure. Our results suggest,
+therefore, that there is no strong evidence for anomalous anisotropy in the
+LSS, given the limitations and systematics of current data, in the concordance
+model scenario.",1606.06751v3
+2016-06-25,Observation of Optical and Electrical In-plane Anisotropy in High-mobility Few-layer ZrTe5,"Transition metal pentatelluride ZrTe5 is a versatile material in
+condensed-matter physics and has been intensively studied since the 1980s. The
+most fascinating feature of ZrTe5 is that it is a 3D Dirac semimetal which has
+linear energy dispersion in all three dimensions in momentum space.
+Structure-wise, ZrTe5 is a layered material held together by weak interlayer
+van der Waals force. The combination of its unique band structure and 2D atomic
+structure provides a fertile ground for more potential exotic physical
+phenomena in ZrTe5 related to 3D Dirac semimentals. However the physical
+properties of its few-layer form have yet to be thoroughly explored. Here we
+report strong optical and electrical in-plane anisotropy of mechanically
+exfoliated few-layer ZrTe5. Raman spectroscopy shows significant intensity
+change with sample orientations, and the behavior of angle-resolved phonon
+modes at the gamma point is explained by theoretical calculation. DC
+conductance measurement indicates a 50% of difference along different in-plane
+directions. The diminishing of resistivity anomaly in few-layer samples
+indicates the evolution of band structure with reduced thickness.
+Low-temperature Hall experiment sheds lights on more intrinsic anisotropic
+electrical transport, with hole mobility of 3,000 and 1,500 cm2/Vs along a-axis
+and c-axis respectively. Pronounced quantum oscillations in magneto-resistance
+are observed at low temperatures with highest electron mobility up to 44,000
+cm2/Vs.",1606.07960v2
+2016-07-03,Lattice Defects and the Mechanical Anisotropy of Borophene,"Using density functional theory combined with a semi-empirical van der Waals
+dispersion correction, we have investigated the stability of lattice defects
+including boron vacancy, substitutional and interstitial X (X=H, C, B, N, O)
+and $\Sigma$5 tilt grain boundaries in borophene and their influence on the
+anisotropic mechanical properties of this two-dimensional system. The pristine
+borophene has significant in-plane Young's moduli and Poisson's ratio
+anisotropy due to its strong and highly coordinated B-B bonds. The
+concentration of B vacancy and $\Sigma$5 grain boundary could be rather high
+given that their formation energies are as low as 0.10 eV and 0.06 eV/$\AA$
+respectively. In addition, our results also suggest that borophene can react
+easily with H$_2$, O$_2$ and N$_2$ when exposed to these molecules. We find
+that the mechanical properties of borophene are remarkably degraded by these
+defects. The anisotropy in Poisson's ratio, however, can be tuned by some of
+them. Furthermore, the adsorbed H or substitutional C may induce remarkably
+negative Poisson's ratio in borophene, and the substitutional C or N can
+significantly increase the Poisson's ratio by contrast.",1607.00642v4
+2016-07-29,Searching for Cosmic Strings in CMB Anisotropy Maps using Wavelets and Curvelets,"We use wavelet and curvelet transforms to extract signals of cosmic strings
+from cosmic microwave background (CMB) temperature anisotropy maps, and to
+study the limits on the cosmic string tension which various ongoing CMB
+temperature anisotropy experiments will be able to achieve. We construct sky
+maps with size and angular resolution corresponding to various experiments.
+These maps contain the signals of a scaling solution of long string segments
+with a given string tension $G \mu$, the contribution of the dominant Gaussian
+primordial cosmological fluctuations, and pixel by pixel white noise with an
+amplitude corresponding to the instrumental noise of the various experiments.
+In the case that we include white noise, we find that the curvelets are more
+powerful than wavelets. For maps with Planck specification, we obtain bounds on
+the string tension comparable to what was obtained by the Planck collaboration.
+Experiments with better angular resolution such as the South Pole Telescope
+third generation (SPT-3G) survey will be able to yield stronger limits. For
+maps with a specification of SPT-3G we find that string signals will be visible
+down to a string tension of $G \mu = 1.4 \times 10^{-7}$.",1608.00004v2
+2016-08-09,Compensated ferrimagnetic tetragonal Heusler thin films for antiferromagnetic spintronics,"In recent years, antiferromagnetic spintronics has received much attention
+since ideal antiferromagnets do not produce stray fields and are much more
+stable to external magnetic fields compared to materials with net
+magnetization. Akin to antiferromagnets, compensated ferrimagnets have zero net
+magnetization but have the potential for large spin-polarization and strong out
+of plane magnetic anisotropy, and, hence, are ideal candidates for high density
+memory applications. Here, we demonstrate that a fully compensated magnetic
+state with a tunable magnetic anisotropy is realized in Mn-Pt-Ga based
+tetragonal Heusler thin films. Furthermore, we show that a bilayer formed from
+a fully compensated and a partially compensated Mn-Pt-Ga layer, exhibits a
+large interfacial exchange bias up to room temperature. The present work
+establishes a novel design principle for spintronic devices that are formed
+from materials with similar elemental compositions and nearly identical crystal
+and electronic structures. Such devices are of significant practical value due
+to their improved properties such as thermal stability. The flexible nature of
+Heusler materials to achieve tunable magnetizations, and anisotropies within
+closely matched materials provides a new direction to the growing field of
+antiferromagnetic spintronics.",1608.02887v1
+2016-08-29,Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses,"Using liquid phase epitaxy (LPE) technique (111) yttrium iron garnet (YIG)
+films with thicknesses of ~100 nm and surface roughnesses as low as 0.3 nm have
+been grown as a basic material for spin-wave propagation experiments in
+microstructured waveguides. The continuously strained films exhibit nearly
+perfect crystallinity without significant mosaicity and with effective lattice
+misfits of delta a(perpendicular)/a(substrate) ~10-4 and below. The
+film/substrate interface is extremely sharp without broad interdiffusion layer
+formation. All LPE films exhibit a nearly bulk-like saturation magnetization of
+(1800+-20) Gs and an `easy cone' anisotropy type with extremely small in-plane
+coercive fields <0.2 Oe. There is a rather weak in-plane magnetic anisotropy
+with a pronounced six-fold symmetry observed for saturation field <1.5 Oe. No
+significant out-of-plane anisotropy is observed, but a weak dependence of the
+effective magnetization on the lattice misfit is detected. The narrowest
+ferromagnetic resonance linewidth is determined to be 1.4 Oe @ 6.5 GHz which is
+the lowest value reported so far for YIG films of 100 nm thicknesses and below.
+The Gilbert damping coefficient for investigated LPE films is estimated to be
+close to 1 x 10-4.",1608.08043v1
+2016-08-29,Detecting 3D vegetation structure with the Galileo space probe: Can a distant probe detect vegetation structure on Earth?,"Sagan et al. (1993) used the Galileo space probe data and first principles to
+find evidence of life on Earth. Here we ask whether Sagan et al. (1993) could
+also have detected whether life on Earth had three-dimensional structure, based
+on the Galileo space probe data. We reanalyse the data from this probe to see
+if structured vegetation could have been detected in regions with abundant
+photosynthetic pigments through the anisotropy of reflected shortwave
+radiation. We compare changing brightness of the Amazon forest (a region where
+Sagan et al. (1993) noted a red edge in the reflectance spectrum, indicative of
+photosynthesis) as the planet rotates to a common model of reflectance
+anisotropy and found measured increase of surface reflectance of 0.019 versus a
+0.007 predicted from only anisotropic effects. We hypothesize the difference
+was due to minor cloud contamination. However, the Galileo dataset had only a
+small change in phase angle (sun-satellite position) which reduced the observed
+anisotropy signal and we demonstrate that theoretically if the probe had a
+variable phase angle between 0-20, there would have been a much larger
+predicted change in surface reflectance of 0.06 and under such a scenario
+three-dimensional vegetation structure on Earth could possibly have been
+detected. These results suggest that anisotropic effects may be useful to help
+determine whether exoplanets have three-dimensional vegetation structure in the
+future but that further comparisons between empirical and theoretical results
+are first necessary.",1608.08125v1
+2016-09-28,Beyond the Maltese cross: geometry of turbulence between 0.2 and 1 AU,"The spectral anisotropy of turbulent structures has been measured in the
+solar wind since 1990, relying on the assumption of axisymmetry about the mean
+magnetic field, B0. However, several works indicate that this hypothesis might
+be partially wrong, thus raising two questions: (i) is it correct to interpret
+measurements at 1 AU (the so-called Maltese cross) in term of a sum of slab and
+2D turbulence? (ii) what information is really contained in the Maltese cross?
+  We solve direct numerical simulations of the MHD equations including the
+transverse stretching exerted by the solar wind flow and study the genuine 3D
+anisotropy of turbulence as well as that one resulting from the assumption of
+axisymmetry about B0. We show that the evolution of the turbulent spectrum from
+0.2 to 1 AU depends strongly on its initial anisotropy. An axisymmetric
+spectrum with respect to B0 keeps its axisymmetry, i.e., resists stretching
+perpendicular to radial, while an isotropic spectrum becomes essentially
+axisymmetric with respect to the radial direction.
+  We conclude that close to the Sun, slow-wind turbulence has a spectrum that
+is axisymmetric around B0 and the measured 2D component at 1 AU describes the
+real shape of turbulent structures. On the contrary, fast-wind turbulence has a
+more isotropic spectrum at the source and becomes radially symmetric at 1 AU.
+Such structure is hidden by the symmetrization applied to the data that instead
+returns a slab geometry.",1609.09094v1
+2016-09-30,Antiferromagnetic THz-frequency Josephson-like Oscillator Driven by Spin Current,"The development of compact and tunable room temperature sources of coherent
+THz-frequency signals would open a way for numerous new applications. The
+existing approaches to THz-frequency generation based on superconductor
+Josephson junctions (JJ), free electron lasers, and quantum cascades require
+cryogenic temperatures or/and complex setups, preventing the miniaturization
+and wide use of these devices. We demonstrate theoretically that a bi-layer of
+a heavy metal (Pt) and a bi-axial antiferromagnetic (AFM) dielectric (NiO) can
+be a source of a coherent THz signal. A spin-current flowing from a
+DC-current-driven Pt layer and polarized along the hard AFM anisotropy axis
+excites a non-uniform in time precession of magnetizations sublattices in the
+AFM, due to the presence of a weak easy-plane AFM anisotropy. The frequency of
+the AFM oscillations varies in the range of 0.1-2.0 THz with the driving
+current in the Pt layer from $10^8\text{A}/\text{cm}^2$ to
+$10^9\text{A}/\text{cm}^2$. The THz-frequency signal from the AFM with the
+amplitude exceeding 1 V/cm is picked up by the inverse spin-Hall effect in Pt.
+The operation of a room-temperature AFM THz-frequency oscillator is similar to
+that of a cryogenic JJ oscillator, with the energy of the easy-plane magnetic
+anisotropy playing the role of the Josephson energy.",1609.09866v1
+2016-11-28,Atomistic simulation of finite temperature magnetism of nanoparticles: application to cobalt clusters on Au(111),"We developed a technique to determine suitable spin models for small embedded
+clusters of arbitrary geometry by combining the spin-cluster expansion with the
+relativistic disordered local moment scheme. We present results for uncovered
+and covered hexagonal Co clusters on Au(111) surface, and use classical Monte
+Carlo simulations to study the temperature dependent properties of the systems.
+To test the new method we compare the calculated spin-model parameters of the
+uncovered clusters with those of a Co monolayer deposited on Au(111). In
+general, the isotropic and DM interactions are larger between atoms at the
+perimeter than at the center of the clusters. For Co clusters covered by Au,
+both the contribution to the magnetic anisotropy and the easy axis direction of
+the perimeter atoms differ from those of the inner atoms due to reduced
+symmetry. We investigate the spin reversals of the covered clusters with
+perpendicular magnetic anisotropy and by measuring the magnetization variance
+in the easy direction we suggest a technique to determine the blocking
+temperature of superparamagnetic particles. We also determine the N\'eel
+relaxation time from the Monte Carlo simulations and find that it satisfies the
+N\'eel--Arrhenius law with an energy barrier close to the magnetic anisotropy
+energy of the clusters.",1611.09199v2
+2016-12-17,"Upper critical field, pressure-dependent superconductivity and electronic anisotropy of Sm$_4$Fe$_2$As$_2$Te$_{1-x}$O$_{4-y}$F$y$","We present a detailed study of the electrical transport properties of a
+recently discovered iron-based superconductor:
+Sm$_4$Fe$_2$As$_2$Te$_{0.72}$O$_{2.8}$F$_{1.2}$. We followed the temperature
+dependence of the upper critical field by resistivity measurement of single
+crystals in magnetic fields up to 16 T, oriented along the two main
+crystallographic directions. This material exhibits a zero-temperature upper
+critical field of 90 T and 65 T parallel and perpendicular to the Fe$_2$As$_2$
+planes, respectively. An unprecedented superconducting magnetic anisotropy
+$\gamma_H=H_{c2}^{ab}/H_{c2}^c \sim 14$ is observed near Tc, and it decreases
+at lower temperatures as expected in multiband superconductors. Direct
+measurement of the electronic anisotropy was performed on microfabricated
+samples, showing a value of $\rho_c/\rho_{ab}(300K) \sim 5$ that raises up to
+19 near Tc. Finally, we have studied the pressure and temperature dependence of
+the in-plane resistivity. The critical temperature decreases linearly upon
+application of hydrostatic pressure (up to 2 GPa) similarly to overdoped
+cuprate superconductors. The resistivity shows saturation at high temperatures,
+suggesting that the material approaches the Mott-Ioffe-Regel limit for metallic
+conduction. Indeed, we have successfully modelled the resistivity in the normal
+state with a parallel resistor model that is widely accepted for this state.
+All the measured quantities suggest strong pressure dependence of the density
+of states.",1612.05792v1
+2016-12-21,"Spin Pumping, Dissipation, and Direct and Alternating Inverse Spin Hall Effects in Magnetic Insulator-Normal Metal Bilayers","We theoretically consider the spin-wave mode- and wavelength-dependent
+enhancement of the Gilbert damping in magnetic insulator--normal metal bilayers
+due to spin pumping as well as the enhancement's relation to direct and
+alternating inverse spin Hall voltages in the normal metal. In the
+long-wavelength limit, including long-range dipole interactions, the ratio of
+the enhancement for transverse volume modes to that of the macrospin mode is
+equal to two. With an out-of-plane magnetization, this ratio decreases with
+both an increasing surface anisotropic energy and mode number. If the surface
+anisotropy induces a surface state, the enhancement can be an order of
+magnitude larger than for to the macrospin. With an in-plane magnetization, the
+induced dissipation enhancement can be understood by mapping the anisotropy
+parameter to the out-of-plane case with anisotropy. For shorter wavelengths, we
+compute the enhancement numerically and find good agreement with the analytical
+results in the applicable limits. We also compute the induced direct- and
+alternating-current inverse spin Hall voltages and relate these to the magnetic
+energy stored in the ferromagnet. Because the magnitude of the direct spin Hall
+voltage is a measure of spin dissipation, it is directly proportional to the
+enhancement of Gilbert damping. The alternating spin Hall voltage exhibits a
+similar in-plane wave-number dependence, and we demonstrate that it is greatest
+for surface-localized modes.",1612.07020v2
+2016-12-21,CMB-lensing beyond the leading order: temperature and polarization anisotropies,"We investigate the weak lensing corrections to the CMB temperature and
+polarization anisotropies. We consider all the effects beyond the leading
+order: post-Born corrections, LSS corrections and, for the polarization
+anisotropies, the correction due to the rotation of the polarization direction
+between the emission at the source and the detection at the observer. We show
+that the full next-to-leading order correction to the B-mode polarization is
+not negligible on small scales and is dominated by the contribution from the
+rotation, this is a new effect not taken in account in previous works.
+Considering vanishing primordial gravitational waves, the B-mode correction due
+to rotation is comparable to cosmic variance for $\ell \gtrsim 3500$, in
+contrast to all other spectra where the corrections are always below that
+threshold for a single multipole. Moreover, the sum of all the effects is
+larger than cosmic variance at high multipoles, showing that higher-order
+lensing corrections to B-mode polarization are in principle detectable.",1612.07263v3
+2017-01-14,Crossovers due to anisotropy and disorder in quantum critical fluctuations,"Scaling relations are used to study cross-overs, due to anisotropic spin
+interactions or single ion anisotropy, and due to disorder, in the
+thermodynamics and correlation functions near quantum-critical transitions. The
+principal results are simple with a wide range of applications. The region of
+attraction to the stable anisotropic fixed point in the quantum-critical region
+is exponentially enhanced by the dynamical critical exponent $z$ compared to
+the region of attraction to the fixed point in the quantum disordered region.
+The result implies that, even for small anisotropy, the region of attraction to
+the stable incommensurate Ising or planar metallic anti-ferromagnetic critical
+points, which belong to the universality class of the XY model with $z \to
+\infty$, covers the entire quantum-critical region. In crossovers due to
+disorder, the instability of the pure fixed point in the quantum disordered
+region is exponentially enhanced by $z$ compared to that in the
+quantum-critical region. This result suggests that for some classes of disorder
+and for large enough $z$, one may find singularities in the correlations as a
+function of frequency and temperature down to very low temperatures even though
+the correlation length in space remains short range.",1701.03853v3
+2017-01-24,"Helical paths, gravitaxis, and separation phenomena for mass-anisotropic self-propelling colloids: experiment versus theory","The self-propulsion mechanism of active colloidal particles often generates
+not only translational but also rotational motion. For particles with an
+anisotropic mass density under gravity, the motion is usually influenced by a
+downwards oriented force and an aligning torque. Here we study the trajectories
+of self-propelled bottom-heavy Janus particles in three spatial dimensions both
+in experiments and by theory. For a sufficiently large mass anisotropy, the
+particles typically move along helical trajectories whose axis is oriented
+either parallel or antiparallel to the direction of gravity (i.e., they show
+gravitaxis). In contrast, if the mass anisotropy is small and rotational
+diffusion is dominant, gravitational alignment of the trajectories is not
+possible. Furthermore, the trajectories depend on the angular self-propulsion
+velocity of the particles. If this component of the active motion is strong and
+rotates the direction of translational self-propulsion of the particles, their
+trajectories have many loops, whereas elongated swimming paths occur if the
+angular self-propulsion is weak. We show that the observed gravitational
+alignment mechanism and the dependence of the trajectory shape on the angular
+self-propulsion can be used to separate active colloidal particles with respect
+to their mass anisotropy and angular self-propulsion, respectively.",1701.06824v2
+2017-01-02,Ferromagnetic films with three to twenty spin layers as described using second order perturbed Heisenberg Hamiltonian,"Modified second order perturbed Heisenberg Hamiltonian was employed to
+describe the magnetic properties of ferromagnetic films with three to twenty
+spin layers for the first time. Previously, the solution of second order
+perturbed Heisenberg Hamiltonian was found for ferromagnetic films with two to
+five layers under some assumptions by us. In this report, the exact solution is
+presented without any assumptions by calculating the pseudo inverse of matrix
+C. All eight magnetic parameters such as spin exchange interaction, second
+order magnetic anisotropy, fourth order magnetic anisotropy, stress induced
+magnetic anisotropy, demagnetization factor, in plane magnetic field, out of
+plane magnetic field and magnetic dipole interaction were taken into account.
+The easy and hard directions were found using 3-D and 2-D plots of total
+magnetic energy versus these magnetic parameters. Angle between easy and hard
+directions was nearly 107 degrees in many cases. The magnetic easy axis
+gradually rotates from out of plane to in plane direction by indicating a
+preferred in plane orientation of magnetic easy axis for films with higher
+number of spin layers. These theoretical results agree with some experimental
+research data of ferromagnetic thin films.",1701.07780v1
+2017-02-09,Modification of microstructure and micromagnetic properties in Gd-Fe thin films by rapid thermal processing,"Impact of rapid thermal processing (RTP) on microstructure and magnetic
+properties of Gd-Fe thin films have been investigated with a special emphasis
+to magnetic microstructure. 100 nm thick amorphous Gd-Fe film shows elongated
+stripe domains with characteristic feature size of 122 nm, which signifies the
+development of perpendicular magnetic anisotropy (PMA) in this system. RTP at
+550^oC for different time intervals viz. 5, 10, 15, 20 minutes induces the
+crystallization of Fe over the amorphous Gd-Fe matrix. Cross-sectional imaging
+with transmission electron microscope reveals the presence of Fe nanocrystal
+and the reacted film-substrate interface, which has also been verified by
+Rutherford backscattering spectrometry. With increasing RTP time, the
+characteristic size and the threshold height of the topographic feature
+increases. While the magnetic contrast drops down for the processed films, the
+increasing threshold height of the nanocrystalline grains results a topography
+dominated mixed phase in the magnetic force microscopy images. The
+magnetization measurements clearly indicate a re-orientation of the
+magnetization direction from perpendicular to the plane of the surface. To
+unravel the effect of anisotropy modification on domain structure, 3D
+micromagnetic simulations have been performed, which showed that with 50%
+reduction of original anisotropy, the magnetization tries to orient in the
+plane of the surface, whereas an in-plane (along xz plane) tilt angle of 30^o
+has been estimated to be the threshold for the decrease in perpendicular
+component of magnetization in the investigated Gd-Fe thin film system.",1702.02987v2
+2017-02-23,Measurement of Anisotropy and Search for UHECR Sources,"Ultra-high energy cosmic rays (UHECRs) are particles, likely protons and/or
+nuclei, with energies up to $10^{20}$ eV that are observed through the giant
+air showers they produce in the atmosphere. These particles carry the
+information on the most extreme phenomena in the Universe. At these energies,
+even charged particles could be magnetically rigid enough to keep track of, or
+even point directly to, the original positions of their sources on the sky. The
+discovery of anisotropy of UHECRs would thus signify opening of an entirely new
+window onto the Universe. With the construction and operation of the new
+generation of cosmic ray experiments -- the Pierre Auger Observatory in the
+Southern hemisphere and the Telescope Array in the Northern one -- the study of
+these particles, the most energetic ever detected, has experienced a jump in
+statistics as well as in the data quality, allowing for a much better
+sensitivity in searching for their sources. In this review, we summarize the
+searches for anisotropies and the efforts to identify the sources of UHECRs
+which have been carried out using these new data.",1702.07209v1
+2017-02-27,Far-from-equilibrium initial conditions probed by a nonlocal observable,"Using the gauge/gravity duality, we investigate the evolution of an
+out-of-equilibrium strongly-coupled plasma from the viewpoint of the two-point
+function of scalar gauge-invariant operators with large conformal dimension.
+This system is out of equilibrium due to the presence of anisotropy and/or a
+massive scalar field. Considering various functions for the initial anisotropy
+and scalar field, we conclude that the effect of the anisotropy on the
+evolution of the two-point function is considerably more than the effect of the
+scalar field. We also show that the ordering of the equilibration time of the
+one-point function for the non-probe scalar field and the correlation function
+between two points with a fixed separation can be reversed by changing the
+initial configuration of the plasma, when the system is out of the equilibrium
+due to the presence of at least two different sources like our problem. In
+addition, we find the equilibration time of the two-point function to be
+linearly increasing with respect to the separation of the two points with a
+fixed slope, regardless of the initial configuration that we start with.
+Finally we observe that, for larger separations the geodesic connecting two
+points on the boundary crosses the event horizon after it has reached its final
+equilibrium value, meaning that the two-point function can probe behind the
+event horizon.",1702.08482v2
+2017-04-11,Uniaxial strain control of spin-polarization in multicomponent nematic order of BaFe$_{2}$As$_{2}$,"The iron-based high temperature superconductors exhibit a rich phase diagram
+reflecting a complex interplay between spin, lattice, and orbital degrees of
+freedom [1-4]. The nematic state observed in many of these compounds epitomizes
+this complexity, by entangling a real-space anisotropy in the spin fluctuation
+spectrum with ferro-orbital order and an orthorhombic lattice distortion [5-7].
+A more subtle and much less explored facet of the interplay between these
+degrees of freedom arises from the sizable spin-orbit coupling present in these
+systems, which translates anisotropies in real space into anisotropies in spin
+space. Here, we present a new technique enabling nuclear magnetic resonance
+under precise tunable strain control, which reveals that upon application of a
+tetragonal symmetry-breaking strain field, the magnetic fluctuation spectrum in
+the paramagnetic phase of BaFe$_{2}$As$_{2}$ also acquires an anisotropic
+response in spin-space. Our results unveil a hitherto uncharted internal spin
+structure of the nematic order parameter, indicating that similar to liquid
+crystals, electronic nematic materials may offer a novel route to
+magneto-mechanical control.",1704.03566v1
+2017-04-21,Strain-gradient-induced magnetic anisotropy in straight-stripe mixed-phase bismuth ferrites: An insight into flexomagnetic phenomenon,"Implementation of antiferromagnetic compounds as active elements in
+spintronics has been hindered by their insensitive nature against external
+perturbations which causes difficulties in switching among different
+antiferromagnetic spin configurations. Electrically-controllable strain
+gradient can become a key parameter to tune the antiferromagnetic states of
+multiferroic materials. We have discovered a correlation between an
+electrically-written straight-stripe mixed-phase boundary and an in-plane
+antiferromagnetic spin axis in highly-elongated La-5%-doped BiFeO$_{3}$ thin
+films by performing polarization-dependent photoemission electron microscopy in
+conjunction with cluster model calculations. Model Hamiltonian calculation for
+the single-ion anisotropy including the spin-orbit interaction has been
+performed to figure out the physical origin of the link between the strain
+gradient present in the mixed phase area and its antiferromagnetic spin axis.
+Our findings enable estimation of the strain-gradient-induced magnetic
+anisotropy energy per Fe ion at around 5$\times$10$^{-12}$ eV m, and provide a
+new pathway towards an electric-field-induced 90$^{\circ}$ rotation of
+antiferromagnetic spin axis at room temperature by flexomagnetism.",1704.06627v1
+2017-05-05,Extragalactic Sources and Propagation of UHECRs,"With the publicly available astrophysical simulation framework for
+propagating extraterrestrial UHE particles, CRPropa 3, it is now possible to
+study realistic UHECR source scenarios including deflections in Galactic and
+extragalactic magnetic fields in an efficient way. Here we discuss three recent
+studies that have already been done in that direction. The first one
+investigates what can be expected in the case of maximum allowed intergalactic
+magnetic fields. Here is shown that, even if voids contain strong magnetic
+fields, deflections of protons with energies $\gtrsim 60 \; \text{EeV}$ from
+nearby sources might be small enough to allow for UHECR astronomy. The second
+study looks into several scenarios with a smaller magnetization focusing on
+large-scale anisotropies. Here is shown that the local source distribution can
+have a more significant effect on the large-scale anisotropy than the EGMF
+model. A significant dipole component could, for instance, be explained by a
+dominant source within 5 Mpc distance. The third study looks into whether
+UHECRs can come from local radio galaxies. If this is the case it is difficult
+to reproduce the observed low level of anisotropy. Therefore is concluded that
+the magnetic field strength in voids in the EGMF model used here is too low
+and/or there are additional sources of UHECRs that were not taken into account
+in these simulations.",1705.02293v1
+2017-05-15,Unconventional magnetic anisotropy in one-dimentional Rashba system realized by adsorbing Gd atom on zigzag graphene nanoribbons,"The Rashba effect, a spin splitting in electronic band structure, attracts
+much attention for the potential applications in spintronics with no
+requirement of external magnetic field. Realizing one-dimensional (1D) Rashba
+system is a big challenge due to the difficulties of growing high-quality
+heavy-metal nanowires or introducing strong spin-orbit coupling (SOC) and
+broken inversion symmetry in flexible materials. Here, based on
+first-principles calculations, we propose a pathway to realize the Rashba
+spin-split by adsorbing Gd atom on zigzag graphene nanoribbons (Gd-ZGNR) and
+further investigate the magnetic anisotropy energy (MAE). Perpendicular MAE and
+unconventional MAE contributions in k-space are found in the self-assembled
+Gd-ZGNR system, which present a remarkable Rashba effect (the estimated
+strength is 1.89 eV {\AA}) attributed to strong SOC (~65.6 meV) and the
+asymmetric adsorption site at the nanoribbons edge. Moreover, first-order MAE
+is connected to the intrinsic Rashba effect beyond the traditional second-order
+MAE, which is confirmed based on the analysis of electronic structures
+perturbed with SOC in comparison with metastable Gd-ZGNR at central symmetric
+adsorption site. The dependence of first-order MAE as well as Rashba effect of
+Gd-ZGNRs on the ribbon width are also examined. This work offers new
+perspective to achieve 1D Rashba system and provides fundamental understanding
+on the magnetic anisotropy, which would be of great significance for searching
+Majorana fermions and promoting the potential applications in spintronics.",1705.05121v2
+2017-05-22,Time-of-flight elastic and inelastic neutron scattering studies on the localized $4d$ electron layered perovskite La$_5$Mo$_4$O$_{16}$,"The magnetic structure and spin-wave excitations in the quasi-square-lattice
+layered perovskite compound La$_5$Mo$_4$O$_{16}$ were studied by a combination
+of neutron diffraction and inelastic neutron scattering techniques using
+polycrystalline sample. Neutron powder diffraction refinement revealed that the
+magnetic structure is ferrimagnetic in the $ab$ plane with antiferromagnetic
+stacking along the $c$ axis where the magnetic propagation vector is
+$\mathbf{k}=\left(0,0,\frac{1}{2}\right)$. The ordered magnetic moments are
+estimated to be $0.54(2)\mu_\text{B}$ for Mo$^{5+}$ ($4d^1$) ions and
+$1.07(3)\mu_\text{B}$ for Mo$^{4+}$ ($4d^2$) ions at 4 K, which are about half
+of the expected values. The inelastic neutron scattering results display strong
+easy-axis magnetic anisotropy along the $c$ axis due to the spin-orbit
+interaction in Mo ions evidenced by the spin gap at the magnetic zone center.
+The model Hamiltonian consisting of in-plane anisotropic exchange interactions,
+the interlayer exchange interaction, and easy-axis single-ion anisotropy can
+explain our inelastic neutron scattering data well. Strong Ising-like
+anisotropy and weak interlayer coupling compared with the intralayer exchange
+interaction can explain both the high-temperature magnetoresistance and
+long-time magnetization decay recently observed in La$_5$Mo$_4$O$_{16}$.",1705.07916v1
+2017-06-05,How important is non-ideal physics in simulations of sub-Eddington accretion onto spinning black holes?,"Black holes with accretion rates well below the Eddington rate are expected
+to be surrounded by low-density, hot, geometrically thick accretion disks. This
+includes the two black holes being imaged at sub-horizon resolution by the
+Event Horizon Telescope. In these disks, the mean free path for Coulomb
+interactions between charged particles is large, and the accreting matter is a
+nearly collisionless plasma. Despite this, numerical simulations have so far
+modeled these accretion flows using ideal magnetohydrodynamics. Here, we
+present the first global, general relativistic, 3D simulations of accretion
+flows onto a Kerr black hole including the non-ideal effects most likely to
+affect the dynamics of the disk: the anisotropy between the pressure parallel
+and perpendicular to the magnetic field, and the heat flux along magnetic field
+lines. We show that for both standard and magnetically arrested disks, the
+pressure anisotropy is comparable to the magnetic pressure, while the heat flux
+remains dynamically unimportant. Despite this large pressure anisotropy,
+however, the time-averaged structure of the accretion flow is strikingly
+similar to that found in simulations treating the plasma as an ideal fluid. We
+argue that these similarities are largely due to the interchangeability of the
+viscous and magnetic shear stresses as long as the magnetic pressure is small
+compared to the gas pressure, and to the sub-dominant role of pressure/viscous
+effects in magnetically arrested disks. We conclude by highlighting outstanding
+questions in modeling the dynamics of low collisionality accretion flows.",1706.01533v1
+2017-06-14,Behavior of the Universe anisotropy in a big-bounce cosmology,"We investigate the classical and quantum behavior of a Bianchi I model in the
+presence of a stiff matter contribution when the Vilenkin interpretation of the
+wave function of the Universe is taken into account. We study its evolution in
+the so-called polymer representation of quantum mechanics, in order to
+characterize the modifications that a discrete nature in the isotropic variable
+of the Universe induces on the morphology of the cosmological singularity. We
+demonstrate that in such a model the Big-Bang singularity is removed at a
+semiclassical level in favor of a Big-Bounce when a lattice on the isotropic
+variable is considered. Furthermore, the analysis of the mean values on the
+quantum degrees of freedom, \textit{i.e} the variables $\beta_{+},\beta_{-}$ in
+the Misner picture, and the investigation on the evolution of the wave packets
+show how the typical diverging behavior associated to the anisotropies of the
+Universe in proximity of the initial singularity disappears in our polymer
+modified scheme. Indeed, the anisotropies remain finite across the Big-Bounce
+and they assume a value that depends on the initial conditions fixed far from
+the turning point. Finally, we demonstrate that the proposed scenario can be
+extended, with a suitable choice of the configuration parameters, to the
+Bianchi IX cosmology and therefore it can be regarded as a paradigm for the
+generic cosmological model.",1706.04361v1
+2017-06-23,Magnetic properties of quasi-two-dimensional $S$ = 1/2 Heisenberg antiferromagnet with distorted square lattice,"We successfully synthesize single crystals of the verdazyl radical
+$\alpha$-2,3,5-Cl$_3$-V. $Ab$ $initio$ molecular orbital calculations indicate
+that the two dominant antiferromagnetic interactions, $J_{\rm{1}}$ and
+$J_{\rm{2}}$ ($\alpha =J_{\rm{2}}/J_{\rm{1}}\simeq 0.56$), form an $S$ = 1/2
+distorted square lattice. We explain the magnetic properties based on the $S$ =
+1/2 square lattice Heisenberg antiferromagnet using the quantum Monte Carlo
+method, and examine the effects of the lattice distortion and the interplane
+interaction contribution. In the low-temperature regions below 6.4 K, we
+observe anisotropic magnetic behavior accompanied by a phase transition to a
+magnetically ordered state. The electron spin resonance signals exhibit
+anisotropic behavior in the temperature dependence of the resonance field and
+the linewidth. We explain the frequency dependence of the resonance fields in
+the ordered phase using a mean-field approximation with out-of-plane easy-axis
+anisotropy, which causes a spin-flop phase transition at approximately 0.4 T
+for the field perpendicular to the plane. Furthermore, the anisotropic dipole
+field provides supporting information regarding the presence of the easy-axis
+anisotropy. These results demonstrate that the lattice distortion, anisotropy,
+and interplane interaction of this model are sufficiently small that they do
+not affect the intrinsic behavior of the $S$ = 1 / 2 square lattice Heisenberg
+antiferromagnet.",1706.07546v1
+2017-07-11,Interface Dzyaloshinskii-Moriya interaction in the interlayer exchange antiferromagnetic coupled Pt/CoFeB/Ru/CoFeB systems,"Interfacial Dzyaloshinskii-Moriya interaction (iDMI) in interlayer exchange
+coupled (IEC) Pt/Co$_{20}$Fe$_{60}$B$_{20}$(1.12
+nm)/Ru/Co$_{20}$Fe$_{60}$B$_{20}$(1.12 nm) systems have been studied
+theoretically and experimentally. Vibrating sample magnetometer has been used
+to measure their magnetization at saturation and their interlayer exchange
+coupling constants. These latter are found to be of an antiferromagnetic nature
+for the investigated Ru range thickness (0.5-1 nm). Their dynamic magnetic
+properties were studied using Brillouin light scattering (BLS) technique. The
+BLS measurements reveal pronounced non-reciprocal spin waves propagation. In
+contrast to the calculations for symmetrical IEC CoFeB layers, this
+experimental nonreciprocity is Ru thickness and thus coupling strength
+dependent. Therefore, to explain the experimental behaviour, a theoretical
+model based on the perpendicular interface anisotropy difference between the
+bottom and top CoFeB layers has been developed. We show that the Ru thickness
+dependence of the spin wave non-reciprocity is well reproduced by considering a
+constant iDMI and different perpendicular interfacial anisotropy fields between
+the top and bottom CoFeB layers. This anisotropy difference has been confirmed
+by the investigation of the CoFeB thickness dependence of effective
+magnetization of Pt/CoFeB/Ru and Ru/CoFeB/MgO individual layers, where a linear
+behaviour has been observed.",1707.03427v1
+2017-07-14,Symmetry-broken dissipative exchange flows in thin-film ferromagnets with in-plane anisotropy,"Planar ferromagnetic channels have been shown to theoretically support a
+long-range ordered and coherently precessing state where the balance between
+local spin injection at one edge and damping along the channel establishes a
+dissipative exchange flow, sometimes referred to as a spin superfluid. However,
+realistic materials exhibit in-plane anisotropy, which breaks the axial
+symmetry assumed in current theoretical models. Here, we study dissipative
+exchange flows in a ferromagnet with in-plane anisotropy from a dispersive
+hydrodynamic perspective. Through the analysis of a boundary value problem for
+a damped sine-Gordon equation, dissipative exchange flows in a ferromagnetic
+channel can be excited above a spin current threshold that depends on material
+parameters and the length of the channel. Symmetry-broken dissipative exchange
+flows display harmonic overtones that redshift the fundamental precessional
+frequency and lead to a reduced spin pumping efficiency when compared to their
+symmetric counterpart. Micromagnetic simulations are used to verify that the
+analytical results are qualitatively accurate, even in the presence of nonlocal
+dipole fields. Simulations also confirm that dissipative exchange flows can be
+driven by spin transfer torque in a finite-sized region. These results
+delineate the important material parameters that must be optimized for the
+excitation of dissipative exchange flows in realistic systems.",1707.04664v3
+2017-07-19,Engineering elliptical spin-excitations by complex anisotropy fields in Fe adatoms and dimers on Cu(111),"We investigate the dynamics of Fe adatoms and dimers deposited on the Cu(111)
+metallic surface in the presence of spin-orbit coupling, within time-dependent
+density functional theory. The \textit{ab initio} results provide
+material-dependent parameters that can be used in semiclassical approaches,
+which are used for insightful interpretations of the excitation modes. By
+manipulating the surroundings of the magnetic elements, we show that elliptical
+precessional motion may be induced through the modification of the magnetic
+anisotropy energy. We also demonstrate how different kinds of spin precession
+are realized, considering the symmetry of the magnetic anisotropy energy, the
+ferro- or antiferromagnetic nature of the exchange coupling between the
+impurities, and the strength of the magnetic damping. In particular, the normal
+modes of a dimer depend on the initial magnetic configuration, changing
+drastically by going from a ferromagnetic metastable state to the
+antiferromagnetic ground state. By taking into account the effect of the
+damping into their resonant frequencies, we reveal that an important
+contribution arises for strongly biaxial systems and specially for the
+antiferromagnetic dimers with large exchange couplings. Counter intuitively,
+our results indicate that the magnetic damping influences the quantum
+fluctuations by decreasing the zero-point energy of the system.",1707.06087v2
+2017-07-26,Stabilizing isolated skyrmions at low magnetic fields exploiting vanishing magnetic anisotropy,"Skyrmions are topologically protected non-collinear magnetic structures.
+Their stability and dynamics, arising from their topological character, have
+made them ideal information carriers e.g. in racetrack memories. The success of
+such a memory critically depends on the ability to stabilize and manipulate
+skyrmions at low magnetic fields. The driving force for skyrmion formation is
+the non-collinear Dzyaloshinskii-Moriya exchange interaction (DMI) originating
+from spin-orbit coupling (SOC). It competes with both the nearest neighbour
+Heisenberg exchange interaction and the magnetic anisotropy, which favour
+collinear states. While skyrmion lattices might evolve at vanishing magnetic
+fields, the formation of isolated skyrmions in ultra-thin films so far required
+the application of an external field which can be as high as several T. Here,
+we show that isolated skyrmions in a monolayer (ML) of Co epitaxially grown on
+a Ru(0001) substrate can be stabilized at magnetic fields as low as 100 mT.
+Even though SOC is weak in the 4d element Ru, a homochiral spin spiral ground
+state and isolated skyrmions could be detected and laterally resolved using a
+combination of tunneling and anisotropic tunneling magnetoresistance effect in
+spin-sensitive scanning tunneling microscopy (STM). Density functional theory
+(DFT) calculations confirm these chiral magnetic textures, even though the
+stabilizing DMI interaction is weak. We find that the key factor is the absence
+of magnetocristalline anisotropy in this system which enables non-collinear
+states to evolve in spite of weak SOC, opening up a wide choice of materials
+beyond 5d elements.",1707.08519v1
+2017-08-23,Principal-component analysis of two-particle azimuthal correlations in PbPb and pPb collisions at CMS,"For the first time a principle-component analysis is used to separate out
+different orthogonal modes of the two-particle correlation matrix from heavy
+ion collisions. The analysis uses data from sqrt(s[NN]) = 2.76 TeV PbPb and
+sqrt(s[NN]) = 5.02 TeV pPb collisions collected by the CMS experiment at the
+LHC. Two-particle azimuthal correlations have been extensively used to study
+hydrodynamic flow in heavy ion collisions. Recently it has been shown that the
+expected factorization of two-particle results into a product of the
+constituent single-particle anisotropies is broken. The new information
+provided by these modes may shed light on the breakdown of flow factorization
+in heavy ion collisions. The first two modes (""leading"" and ""subleading"") of
+two-particle correlations are presented for elliptical and triangular
+anisotropies in PbPb and pPb collisions as a function of pt over a wide range
+of event activity. The leading mode is found to be essentially equivalent to
+the anisotropy harmonic previously extracted from two-particle correlation
+methods. The subleading mode represents a new experimental observable and is
+shown to account for a large fraction of the factorization breaking recently
+observed at high transverse momentum. The principle-component analysis
+technique has also been applied to multiplicity fluctuations. These also show a
+subleading mode. The connection of these new results to previous studies of
+factorization is discussed.",1708.07113v2
+2017-08-29,Thermal diffusivity and butterfly velocity in anisotropic Q-Lattice models,"By using a holographic method we study a relation between the thermal
+diffusivity ($D_T$) and two quantum chaotic properties, Lyapunov time
+($\tau_L$) and butterfly velocity ($v_B$) in strongly correlated systems. It
+has been shown that $D_T/(v_B^2 \tau_L)$ is universal in some holographic
+models as well as condensed matter systems including the Sachdev-Ye-Kitaev
+(SYK) models. We investigate to what extent this relation is universal in the
+Q-lattice models with infrared (IR) scaling geometry, focusing on the effect of
+spatial anisotropy. Indeed it was shown that $\mathcal{E}_i :=
+D_{T,i}/(v_{B,i}^2 \tau_L)$ ($i=x,y$) is determined only by some scaling
+exponents of the IR metric in the low temperature limit regardless of the
+matter fields and ultraviolet data. Inspired by this observation, in this work,
+we find the concrete expressions for $\mathcal{E}_i$ in terms of the critical
+dynamical exponents $z_i$ in each direction. By analyzing the IR scaling
+geometry we identify the allowed scaling parameter regimes, which enable us to
+compute the allowed range of $\mathcal{E}_i$. We find the lower bound of
+$\mathcal{E}_i$ is always $1/2$, which is not affected by anisotropy, contrary
+to the $\eta/s$ case. However, there may be an upper bound determined by
+anisotropy.",1708.08822v2
+2017-09-06,Room-temperature superparamagnetism due to giant magnetic anisotropy in Mo$_{S}$ defected single-layer MoS$_{2}$,"Room-temperature superparamagnetism due to a large magnetic anisotropy energy
+(MAE) of a single atom magnet has always been a prerequisite for nanoscale
+magnetic devices. Realization of two dimensional (2D) materials such as
+single-layer (SL) MoS$_{2}$, has provided new platforms for exploring magnetic
+effects, which is important for both fundamental research and for industrial
+applications. Here, we use density functional theory (DFT) to show that the
+antisite defect (Mo$_{S}$) in SL MoS$_{2}$ is magnetic in nature with a
+magnetic moment of $\mu$ of $\sim$ 2$\mu_{B}$ and, remarkably, exhibits an
+exceptionally large atomic scale
+MAE$=\varepsilon_{\parallel}-\varepsilon_{\perp}$ of $\sim$500 meV. Our
+calculations reveal that this giant anisotropy is the joint effect of strong
+crystal field and significant spin-orbit coupling (SOC). In addition, the
+magnetic moment $\mu$ can be tuned between 1$\mu_{B}$ and 3$\mu_{B}$ by varying
+the Fermi energy $\varepsilon_{F}$, which can be achieved either by changing
+the gate voltage or by chemical doping. We also show that MAE can be raised to
+$\sim$1 eV with n-type doping of the MoS$_{2}$:Mo$_{S}$ sample. Our systematic
+investigations deepen our understanding of spin-related phenomena in SL
+MoS$_{2}$ and could provide a route to nanoscale spintronic devices.",1709.01653v1
+2017-09-13,Effects of spatial curvature and anisotropy on the asymptotic regimes in Einstein-Gauss-Bonnet gravity,"In this paper we address two important issues which could affect reaching the
+exponential and Kasner asymptotes in Einstein-Gauss-Bonnet cosmologies --
+spatial curvature and anisotropy in both three- and extra-dimensional
+subspaces. In the first part of the paper we consider cosmological evolution of
+spaces being the product of two isotropic and spatially curved subspaces. It is
+demonstrated that the dynamics in $D=2$ (the number of extra dimensions) and $D
+\geqslant 3$ is different. It was already known that for the $\Lambda$-term
+case there is a regime with ""stabilization"" of extra dimensions, where the
+expansion rate of the three-dimensional subspace as well as the scale factor
+(the ""size"") associated with extra dimensions reach constant value. This regime
+is achieved if the curvature of the extra dimensions is negative. We
+demonstrate that it take place only if the number of extra dimensions is $D
+\geqslant 3$. In the second part of the paper we study the influence of initial
+anisotropy. Our study reveals that the transition from Gauss-Bonnet Kasner
+regime to anisotropic exponential expansion (with expanding three and
+contracting extra dimensions) is stable with respect to breaking the symmetry
+within both three- and extra-dimensional subspaces. However, the details of the
+dynamics in $D=2$ and $D \geqslant 3$ are different. Combining the two
+described affects allows us to construct a scenario in $D \geqslant 3$, where
+isotropisation of outer and inner subspaces is reached dynamically from rather
+general anisotropic initial conditions.",1709.04258v1
+2017-09-15,"Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material","Anisotropy effects on flux pinning and flux flow are strongly effective in
+cuprate as well as iron-based superconductors due to their intrinsically
+layered crystallographic structure. However $\textrm{Fe(Se,Te)}$ thin films
+grown on $\textrm{CaF}_2$ substrate result less anisotropic with respect to all
+the other iron based superconductors. We present the first study on the angular
+dependence of the flux flow instability, which occurs in the flux flow regime
+as a current driven transition to the normal state at the instability point
+($I^*$,$V^*$) in the current-voltage characteristics. The voltage jumps are
+systematically investigated as a function of the temperature, the external
+magnetic field, and the angle between the field and the $\textrm{Fe(Se,Te)}$
+film. The scaling procedure based on the anisotropic Ginzburg-Landau approach
+is successfully applied to the observed angular dependence of the critical
+voltage $V^*$. Anyway, we find out that $\textrm{Fe(Se,Te)}$ represents the
+case study of a layered material characterized by a weak anisotropy of its
+static superconducting properties, but with an increased anisotropy in its
+vortex dynamics due to the predominant perpendicular component of the external
+applied magnetic field. Indeed, $I^*$ shows less sensitivity to angle
+variations, thus being promising for high field applications.",1709.05089v3
+2017-09-22,Micromagnetic study of skyrmion stability in confined magnetic structures with perpendicular anisotropy,"Skyrmions are emerging topological spin structures that are potentially
+revolutionary for future data storage and spintronics applications. The
+existence and stability of skyrmions in magnetic materials is usually
+associated to the presence of the Dzyaloshinskii-Moriya interaction (DMI) in
+bulk magnets or in magnetic thin films lacking inversion symmetry. While some
+methods have already been proposed to generate isolated skyrmions in thin films
+with DMI, a thorough study of the conditions under which the skyrmions will
+remain stable in order to be manipulated in an integrated spintronic device are
+still an open problem. The stability of such structures is believed to be a
+result of ideal combinations of perpendicular magnetic anisotropy (PMA), DMI
+and the interplay between geometry and magnetostatics. In the present work we
+show some micromagnetic results supporting previous experimental observations
+of magnetic skyrmions in spin-valve stacks with a wide range of DMI values.
+Using micromagnetic simulations of cobalt-based disks, we obtain the magnetic
+ground state configuration for several values of PMA, DMI and geometric
+parameters. Skyrmion numbers, corresponding to the topological charge, are
+calculated in all cases and confirm the occurrence of isolated, stable, axially
+symmetric skyrmions for several combinations of DMI and anisotropy constant.
+The stability of the skyrmions in disks is then investigated under magnetic
+field and spin-polarized current, in finite temperature, highlighting the
+limits of applicability of these spin textures in spintronic devices.",1709.07559v1
+2017-09-22,The build up of the correlation between halo spin and the large scale structure,"Both simulations and observations have confirmed that the spin of
+haloes/galaxies is correlated with the large scale structure (LSS) with a mass
+dependence such that the spin of low-mass haloes/galaxies tend to be parallel
+with the LSS, while that of massive haloes/galaxies tend to be perpendicular
+with the LSS. It is still unclear how this mass dependence is built up over
+time. We use N-body simulations to trace the evolution of the halo spin-LSS
+correlation and find that at early times the spin of all halo progenitors is
+parallel with the LSS. As time goes on, mass collapsing around massive halo is
+more isotropic, especially the recent mass accretion along the slowest
+collapsing direction is significant and it brings the halo spin to be
+perpendicular with the LSS. Adopting the $fractional$ $anisotropy$ (FA)
+parameter to describe the degree of anisotropy of the large-scale environment,
+we find that the spin-LSS correlation is a strong function of the environment
+such that a higher FA (more anisotropic environment) leads to an aligned
+signal, and a lower anisotropy leads to a misaligned signal. In general, our
+results show that the spin-LSS correlation is a combined consequence of mass
+flow and halo growth within the cosmic web. Our predicted environmental
+dependence between spin and large-scale structure can be further tested using
+galaxy surveys.",1709.07881v1
+2017-10-02,Strong-Coupling Lattice QCD on Anisotropic Lattices,"Anisotropic lattice spacings are mandatory to reach the high temperatures
+where chiral symmetry is restored in the strong coupling limit of lattice QCD.
+Here, we propose a simple criterion for the nonperturbative renormalisation of
+the anisotropy coupling in strongly-coupled SU($N$) or U($N$) lattice QCD with
+massless staggered fermions. We then compute the renormalised anisotropy, and
+the strong-coupling analogue of Karsch's coefficients (the running anisotropy),
+for $N=3$. We achieve high precision by combining diagrammatic Monte Carlo and
+multi-histogram reweighting techniques. We observe that the mean field
+prediction in the continuous time limit captures the nonperturbative scaling,
+but receives a large, previously neglected correction on the unit prefactor.
+Using our nonperturbative prescription in place of the mean field result, we
+observe large corrections of the same magnitude to the continuous time limit of
+the static baryon mass, and of the location of the phase boundary associated
+with chiral symmetry restoration. In particular, the phase boundary, evaluated
+on different finite lattices, has a dramatically smaller dependence on the
+lattice time extent. We also estimate, as a byproduct, the pion decay constant
+and the chiral condensate of massless SU(3) QCD in the strong coupling limit at
+zero temperature.",1710.00611v2
+2017-10-03,Simulations of ultra-high Energy Cosmic Rays in the local Universe and the origin of Cosmic Magnetic Fields,"We simulate the propagation of cosmic rays at ultra-high energies, $\gtrsim
+10^{18}$ eV, in models of extragalactic magnetic fields in constrained
+simulations of the local Universe. We use constrained initial conditions with
+the cosmological magnetohydrodynamics code {\sc ENZO}. The resulting models of
+the distribution of magnetic fields in the local Universe are used in the
+\crpropa code to simulate the propagation of ultra-high energy cosmic rays. We
+investigate the impact of six different magneto-genesis scenarios, both
+primordial and astrophysical, on the propagation of cosmic rays over
+cosmological distances. Moreover, we study the influence of different source
+distributions around the Milky Way. Our study shows that different scenarios of
+magneto-genesis do not have a large impact on the anisotropy measurements of
+ultra-high energy cosmic rays. However, at high energies above the GZK-limit,
+there is anisotropy caused by the distribution of nearby sources, independent
+of the magnetic field model. This provides a chance to identify cosmic ray
+sources with future full-sky measurements and high number statistics at the
+highest energies. Finally, we compare our results to the dipole signal measured
+by the Pierre Auger Observatory. All our source models and magnetic field
+models could reproduce the observed dipole amplitude with a pure iron injection
+composition. Our results indicate that the dipole is observed due to clustering
+of secondary nuclei in direction of nearby sources of heavy nuclei. A light
+injection composition is disfavoured by the non-observation of anisotropy at
+energies of $4-8 \rm\ EeV$.",1710.01353v2
+2017-10-06,Anisotropies of the magnetic field fluctuations at kinetic scales in the solar wind : Cluster observations,"We present the first statistical study of the anisotropy of the magnetic
+field turbulence in the solar wind between 1 and 200Hz, i.e. from proton to
+sub-electron scales. We consider 93 10-minute intervals of Cluster/STAFF
+measurements. We find that the fluctuations $\delta B_{\perp}^2$ are not
+gyrotropic at a given frequency $f$, a property already observed at larger
+scales ($\parallel$/$\perp$ mean parallel/perpendicular to the average magnetic
+${\bf B_0}$). This non-gyrotropy gives indications on the angular distribution
+of the wave vectors ${\bf k}$: at $f <$ 10Hz, we find that $k_{\perp}\gg
+k_{\parallel}$, mainly in the fast wind; at $f >$ 10Hz, fluctuations with a
+non-negligible $k_{\parallel}$ are also present. We then consider the
+anisotropy ratio $\delta B_{\parallel}^2/\delta B_{\perp}^2$, which is a
+measure of the magnetic compressibility of the fluctuations. This ratio, always
+smaller than 1, increases with $f.$ It reaches a value showing that the
+fluctuations are more or less isotropic at electron scales, for $f \geq 50$Hz.
+From 1 to 15-20Hz, there is a strong correlation between the observed
+compressibility and the one expected for the kinetic Alfv\'en waves (KAW),
+which only depends on the total plasma $\beta$. For $f > $ 15-20Hz, the
+observed compressibility is larger than expected for KAW; and it is stronger in
+the slow wind: this could be an indication of the presence of a slow-ion
+acoustic mode of fluctuations, which is more compressive and is favored by the
+larger values of the electron to proton temperature ratio generally observed in
+the slow wind.",1710.02341v1
+2017-10-20,Electron Heating in Low Mach Number Perpendicular shocks. I. Heating Mechanism,"Recent X-ray observations of merger shocks in galaxy clusters have shown that
+the post-shock plasma is two-temperature, with the protons hotter than the
+electrons. By means of two-dimensional particle-in-cell simulations, we study
+the physics of electron irreversible heating in perpendicular low Mach number
+shocks, for a representative case with sonic Mach number of 3 and plasma beta
+of 16. We find that two basic ingredients are needed for electron entropy
+production: (i) an electron temperature anisotropy, induced by field
+amplification coupled to adiabatic invariance; and (ii) a mechanism to break
+the electron adiabatic invariance itself. In shocks, field amplification occurs
+at two major sites: at the shock ramp, where density compression leads to an
+increase of the frozen-in field; and farther downstream, where the shock-driven
+proton temperature anisotropy generates strong proton cyclotron and mirror
+modes. The electron temperature anisotropy induced by field amplification
+exceeds the threshold of the electron whistler instability. The growth of
+whistler waves breaks the electron adiabatic invariance, and allows for
+efficient entropy production. We find that the electron heating efficiency
+displays only a weak dependence on mass ratio (less than 30 percent drop, as we
+increase the mass ratio from 49 up to 1600). We develop an analytical model of
+electron irreversible heating and show that it is in excellent agreement with
+our simulation results.",1710.07648v1
+2017-10-20,Transverse instabilities of stripe domains in magnetic thin films with perpendicular magnetic anisotropy,"Stripe domains are narrow, elongated, reversed regions that exist in magnetic
+materials with perpendicular magnetic anisotropy. Stripe domains appear as a
+pair of domain walls that can exhibit topology with a nonzero chirality. Recent
+experimental and numerical investigations identify an instability of stripe
+domains in the long direction as a means of nucleating isolated magnetic
+skyrmions. Here, the onset and nonlinear evolution of transverse instabilities
+for a dynamic stripe domain known as the bion stripe are investigated. Both
+non-topological and topological variants of the bion stripe are shown to
+exhibit a long-wavelength transverse instability with different characteristic
+features. In the former, small transverse variations in the stripe's width lead
+to a neck instability that eventually pinches the non-topological stripe into a
+chain of two-dimensional breathers composed of droplet soliton pairs. In the
+latter case, small variations in the stripe's center results in a snake
+instability whose topological structure leads to the nucleation of dynamic
+magnetic skyrmions and antiskyrmions as well as perimeter-modulated droplets.
+Quantitative, analytical predictions for both the early, linear evolution and
+the long-time, nonlinear evolution are achieved using an averaged Lagrangian
+approach that incorporates both exchange (dispersion) and anisotropy
+(nonlinearity). The method of analysis is general and can be applied to other
+filamentary structures.",1710.07718v1
+2017-12-04,The Nature of Bonding in Bulk Tellurium Composed of One-Dimensional Helical Chains,"Bulk tellurium (Te) is composed of one-dimensional (1D) helical chains which
+have been considered to be coupled by van der Waals (vdW) interactions.
+However, based on first-principles density-functional theory calculations, we
+here propose a different bonding nature between neighboring chains: i.e., the
+helical chains made of normal covalent bonds are connected together by
+coordinate covalent bonds. It is revealed that the lone pairs of electrons of
+Te atom participate in forming coordinate covalent bonds between neighboring
+chains. Therefore, each Te atom behaves as both electron donor to neighboring
+chains and electron acceptor from neighboring chains. This ligand-metal-like
+bonding nature in bulk Te results in the same order of bulk moduli along the
+directions parallel and perpendicular to the chains, contrasting with the large
+anisotropy of bulk moduli in vdW crystals. We further find that the electron
+effective masses parallel and perpendicular to the chains are almost the same
+each other, consistent with the observed nearly isotropic electrical
+resistivity. It is thus demonstrated that the normal/coordinate covalent bonds
+parallel/perpendicular to the chains in bulk Te lead to a minor anisotropy in
+structural and transport properties, distinct from a strong anisotropy observed
+in the typical two-dimensional (2D) vdW materials such as graphite and MoS$_2$.",1712.00894v1
+2017-12-08,Superconducting and normal-state anisotropy of the doped topological insulator Sr$_{0.1}$Bi$_2$Se$_3$,"Sr$_x$Bi$_2$Se$_3$ and the related compounds Cu$_x$Bi$_2$Se$_3$ and
+Nb$_x$Bi$_2$Se$_3$ have attracted considerable interest, as these materials may
+be realizations of unconventional topological superconductors.
+Superconductivity with T$_c$ ~ 3 K in Sr$_x$Bi$_2$Se$_3$ arises upon
+intercalation of Sr into the layered topological insulator Bi$_2$Se$_3$. Here
+we elucidate the anisotropy of the normal and superconducting state of
+Sr$_{0.1}$Bi$_2$Se$_3$ with angular dependent magnetotransport and
+thermodynamic measurements. High resolution x-ray diffraction studies underline
+the high crystalline quality of the samples. We demonstrate that the normal
+state electronic and magnetic properties of Sr$_{0.1}$Bi$_2$Se$_3$ are
+isotropic in the basal plane while we observe a large two-fold in-plane
+anisotropy of the upper critical field in the superconducting state. Our
+results support the recently proposed odd-parity nematic state characterized by
+a nodal gap of $E_u$ symmetry in Sr$_x$Bi$_2$Se$_3$.",1712.03215v1
+2017-12-09,Periodic chiral magnetic domains in single-crystal nickel nanowires,"We report on experimental and computational investigations of the domain
+structure of ~0.2 x 0.2 x 8 {\mu}m single-crystal Ni nanowires (NWs). The Ni
+NWs were grown by a thermal chemical vapor deposition technique that results in
+highly-oriented single-crystal structures on amorphous SiOx coated Si
+substrates. Magnetoresistance measurements of the Ni NWs suggest the average
+magnetization points largely off the NW long axis at zero field. X-ray
+photoemission electron microscopy images show a well-defined periodic
+magnetization pattern along the surface of the nanowires with a period of
+{\lambda} = 250 nm. Finite element micromagnetic simulations reveal that an
+oscillatory magnetization configuration with a period closely matching
+experimental observation ({\lambda} = 240 nm) is obtainable at remanence. This
+magnetization configuration involves a periodic array of alternating chirality
+vortex domains distributed along the length of the NW. Vortex formation is
+attributable to the cubic anisotropy of the single crystal Ni NW system and its
+reduced structural dimensions. The periodic alternating chirality vortex state
+is a topologically protected metastable state, analogous to an array of
+360{\deg} domain walls in a thin strip. Simulations show that other remanent
+states are also possible, depending on the field history. Effects of material
+properties and strain on the vortex pattern are investigated. It is shown that
+at reduced cubic anisotropy vortices are no longer stable, while negative
+uniaxial anisotropy and magnetoelastic effects in the presence of compressive
+biaxial strain contribute to vortex formation.",1712.03387v1
+2017-12-04,Planck 2015 constraints on the non-flat $φ$CDM inflation model,"We perform Markov chain Monte Carlo analyses to put constraints on the
+non-flat $\phi$CDM inflation model using Planck 2015 cosmic microwave
+background (CMB) anisotropy data and baryon acoustic oscillation distance
+measurements. The $\phi$CDM model is a consistent dynamical dark energy model
+in which the currently accelerating cosmological expansion is powered by a
+scalar field $\phi$ slowly rolling down an inverse power-law potential energy
+density. We also use a physically consistent power spectrum for energy density
+inhomogeneities in this non-flat model. We find that, like the
+closed-$\Lambda$CDM and closed-XCDM models, the closed-$\phi$CDM model provides
+a better fit to the lower multipole region of the CMB temperature anisotropy
+data compared to that provided by the tilted flat-$\Lambda$CDM model. Also,
+like the other closed models, this model reduces the tension between the Planck
+and the weak lensing $\sigma_8$ constraints. However, the higher multipole
+region of the CMB temperature anisotropy data are better fit by the tilted
+flat-$\Lambda$CDM model than by the closed models.",1712.08617v2
+2018-01-09,Epitaxial Heusler Superlattice Co2MnAl/Fe2MnAl with Perpendicular Magnetic Anisotropy and Termination-Dependent Half-Metallicity,"Single-crystal Heusler atomic-scale superlattices that have been predicted to
+exhibit perpendicular magnetic anisotropy and half-metallicity have been
+successfully grown by molecular beam epitaxy. Superlattices consisting of
+full-Heusler Co$_2$MnAl and Fe$_2$MnAl with one to three unit cell periodicity
+were grown on GaAs (001), MgO (001), and Cr (001)/MgO (001). Electron energy
+loss spectroscopy maps confirmed clearly segregated epitaxial Heusler layers
+with high cobalt or high iron concentrations for samples grown near room
+temperature on GaAs (001). Superlattice structures grown with an excess of
+aluminum had significantly lower thin film shape anisotropy and resulted in an
+out-of-plane spin reorientation transition at temperatures below 200 K for
+samples grown on GaAs (001). Synchrotron-based spin resolved photoemission
+spectroscopy found that the superlattice structure improves the Fermi level
+spin polarization near the X point in the bulk Brillouin zone. Stoichiometric
+Co$_2$MnAl terminated superlattice grown on MgO (001) had a spin polarization
+of 95%, while a pure Co$_2$MnAl film had a spin polarization of only 65%.",1801.02787v1
+2018-01-20,"Generalized coupled mode formalism in reciprocal waveguides with gain/loss, anisotropy or bianisotropy","In anisotropic or bianisotropic waveguides, the standard coupled mode theory
+fails due to the broken link between the forward and backward propagating
+modes, which together form the dual mode sets that are crucial in constructing
+couple mode equations. We generalize the coupled mode theory by treating the
+forward and backward propagating modes on the same footing via a generalized
+eigenvalue problem that is exactly equivalent to the waveguide Hamiltonian. The
+generalized eigenvalue problem is fully characterized by two operators, i.e.,
+$( \bar{\bm{L}},\bar{\bm{B}})$, wherein $\bar{\bm{L}}$ is a self-adjoint
+differential operator, while $\bar{\bm{B}}$ is a constant antisymmetric
+operator. From the properties of $\bar{\bm{L}}$ and $\bar{\bm{B}}$, we
+establish the relation between the dual mode sets that are essential in
+constructing coupled mode equations in terms of forward and backward
+propagating modes. By perturbation, the generalized coupled mode equation can
+be derived in a natural way. Our generalized coupled mode formalism can be used
+to study the mode coupling in waveguides that may contain gain/loss, anisotropy
+or bianisotropy. We further illustrate how the generalized coupled theory can
+be used to study the modal coupling in anisotropy and bianisotropy waveguides
+through a few concrete examples.",1801.06673v1
+2018-01-29,Magnetism of a Co monolayer on Pt(111) capped by overlayers of $5d$ elements: a spin-model study,"Using first-principles calculations, we study the magnetic properties of a Co
+monolayer on a Pt(111) surface with a capping monolayer of selected $5d$
+elements (Re, Os, Ir, Pt and Au). First we determine the tensorial exchange
+interactions and magnetic anisotropies characterizing the Co monolayer for all
+considered systems. We find a close relationship between the magnetic moment of
+the Co atoms and the nearest-neighbor isotropic exchange interaction, which is
+attributed to the electronic hybridization between the Co and the capping
+layers, in spirit of the Stoner picture of ferromagnetism. The
+Dzyaloshinskii-Moriya interaction is decreased for all overlayers compared to
+the uncapped Co/Pt(111) system, while even the sign of the
+Dzyaloshinskii-Moriya interaction changes in case of the Ir overlayer. We
+conclude that the variation of the Dzyaloshinskii-Moriya interaction is well
+correlated with the change of the magnetic anisotropy energy and of the orbital
+moment anisotropy. The unique influence of the Ir overlayer on the
+Dzyaloshinskii-Moriya interaction is traced by scaling the strength of the
+spin--orbit coupling of the Ir atoms in Ir/Co/Pt(111) and by changing the Ir
+concentration in the Au$_{1-x}$Ir$_{x}$/Co/Pt(111) system. Our spin dynamics
+simulations indicate that the magnetic ground state of Re/Co/Pt(111) thin film
+is a spin spiral with a tilted normal vector, while the other systems are
+ferromagnetic.",1801.09426v1
+2018-02-09,Co-formation of the Galactic disc and the stellar halo,"Using a large sample of Main Sequence stars with 7-D measurements supplied by
+Gaia and SDSS, we study the kinematic properties of the local (within ~10 kpc
+from the Sun) stellar halo. We demonstrate that the halo's velocity ellipsoid
+evolves strongly with metallicity. At the low [Fe/H] end, the orbital
+anisotropy (the amount of motion in the radial direction compared to the
+tangential one) is mildly radial with 0.2<beta<0.4. However, for stars with
+[Fe/H]>-1.7 we measure extreme values of beta~0.9. Across the metallicity range
+considered, i.e. -3<[Fe/H]<-1, the stellar halo's spin is minimal, at the level
+of 20<v_theta (km/s) <30. Using a suite of cosmological zoom-in simulations of
+halo formation, we deduce that the observed acute anisotropy is inconsistent
+with the continuous accretion of dwarf satellites. Instead, we argue, the
+stellar debris in the inner halo were deposited in a major accretion event by a
+satellite with Mvir>10^10 Msun around the epoch of the Galactic disc formation,
+i.e. between 8 and 11 Gyr ago. The radical halo anisotropy is the result of the
+dramatic radialisation of the massive progenitor's orbit, amplified by the
+action of the growing disc.",1802.03414v1
+2018-02-16,Interplay of phase boundary anisotropy and electro-autocatalytic surface reactions on the lithium intercalation dynamics in Li$_X$FePO$_4$ platelet-like nanoparticles,"Experiments on single crystal Li$_X$FePO$_4$ (LFP) nanoparticles indicate
+rich nonequilibrium phase behavior, such as suppression of phase separation at
+high lithiation rates, striped patterns of coherent phase boundaries,
+nucleation by binarysolid surface wetting and intercalation waves. These
+observations have been successfully predicted (prior to the experiments) by 1D
+depth-averaged phase-field models, which neglect any subsurface phase
+separation. In this paper, using an electro-chemo-mechanical phase-field model,
+we investigate the coherent non-equilibrium subsurface phase morphologies that
+develop in the $ab$- plane of platelet-like single-crystal platelet-like
+Li$_X$FePO$_4$ nanoparticles. Finite element simulations are performed for 2D
+plane-stress conditions in the $ab$- plane, and validated by 3D simulations,
+showing similar results. We show that the anisotropy of the interfacial tension
+tensor, coupled with electroautocatalytic surface intercalation reactions,
+plays a crucial role in determining the subsurface phase morphology. With
+isotropic interfacial tension, subsurface phase separation is observed,
+independent of the reaction kinetics, but for strong anisotropy, phase
+separation is controlled by surface reactions, as assumed in 1D models.
+Moreover, the driven intercalation reaction suppresses phase separation during
+lithiation, while enhancing it during delithiation, by electro-autocatalysis,
+in quantitative agreement with {\it in operando} imaging experiments in
+single-crystalline nanoparticles, given measured reaction rate constants.",1802.05847v1
+2018-03-02,Broadband spectroscopy of thermodynamic magnetization fluctuations through a ferromagnetic spin-reorientation transition,"We use scanning optical magnetometry to study the broadband frequency spectra
+of spontaneous magnetization fluctuations, or ""magnetization noise"", in an
+archetypal ferromagnetic film that can be smoothly tuned through a spin
+reorientation transition (SRT). The SRT is achieved by laterally varying the
+magnetic anisotropy across an ultrathin Pt/Co/Pt trilayer, from the
+perpendicular to in-plane direction, via graded Ar$^+$ irradiation. In regions
+exhibiting perpendicular anisotropy, the power spectrum of the magnetization
+noise, $S(\nu)$, exhibits a remarkably robust $\nu^{-3/2}$ power law over
+frequencies $\nu$ from 1~kHz to 1~MHz. As the SRT region is traversed, however,
+$S(\nu)$ spectra develop a steadily-increasing critical frequency, $\nu_0$,
+below which the noise power is spectrally flat, indicating an evolving
+low-frequency cutoff for magnetization fluctuations. The magnetization noise
+depends strongly on applied in- and out-of-plane magnetic fields, revealing
+local anisotropies and also a field-induced emergence of fluctuations in
+otherwise stable ferromagnetic films. Finally, we demonstrate that higher-order
+correlators can be computed from the noise. These results highlight broadband
+spectroscopy of thermodynamic fluctuations as a powerful tool to characterize
+the interplay between thermal and magnetic energy scales, and as a means of
+characterizing phase transitions in ferromagnets.",1803.00962v1
+2018-03-07,Highly thermally stable sub-20nm magnetic random-access memory based on perpendicular shape anisotropy,"A new approach to increase the downsize scalability of perpendicular STT-MRAM
+is presented. It consists in significantly increasing the thickness of the
+storage layer in out-of-plane magnetized tunnel junctions (pMTJ) as compared to
+conventional pMTJ in order to induce a perpendicular shape anisotropy (PSA) in
+this layer. This PSA is obtained by depositing a thick ferromagnetic (FM) layer
+on top of an MgO/FeCoB based magnetic tunnel junction (MTJ) so that the
+thickness of the storage layer becomes of the order or larger than the diameter
+of the MTJ pillar. In contrast to conventional spin transfer torque magnetic
+random access memory (STT-MRAM) wherein the demagnetizing energy opposes the
+interfacial perpendicular magnetic anisotropy (iPMA), in these novel memory
+cells, both PSA and iPMA contributions favor out-of-plane orientation of the
+storage layer magnetization. Using thicker storage layers in these PSA-STT-MRAM
+has several advantages. Thanks to the PSA, very high and easily tunable thermal
+stability factors can be achieved, even down to sub-10 nm diameters. Moreover,
+low damping material can be used for the thick FM material thus leading to a
+reduction of the write current. The paper describes this new PSA-STT-MRAM
+concept, practical realization of such memory arrays, magnetic characterization
+demonstrating thermal stability factor above 200 for MTJs as small as 8nm in
+diameter and possibility to maintain thermal stability factor above 60 down to
+4nm diameter.",1803.02663v1
+2018-03-13,Spatial Distribution of Globular Clusters in the Galaxy,"The Milky Way's satellite galaxies and Globular Clusters (GCs) are known to
+exhibit an anisotropic spatial distribution. We examine in detail this
+anisotropy by the means of the inertia tensor. We estimate the statistical
+significance of the results by repeating this analysis for random catalogues
+which use the radial distribution of the real sample. Our method reproduces the
+well-known planar structure in the distribution of the satellite galaxies. We
+show that for GCs several anisotropic structures are observed. The GCs at small
+distances, $2<R<10$ kpc, show a structure coplanar with the Galactic plane. At
+smaller and larger distances the whole sample of GCs shows quite weak
+anisotropy. Nevertheless, at largest distances the orientation of the structure
+is close to that of the satellite galaxies, i.e. perpendicular to the Galactic
+plane. We estimate the probability of random realization for this structure of
+1.7%. The Bulge-Disk GCs show a clear disk-like structure lying within the
+galactic disk. The Old Halo GCs show two structures: a well pronounced polar
+elongated structure at $R<3$ kpc which is perpendicular to the galactic plane,
+and a less pronounced disk-like structure coplanar with the galactic disk at
+$6<R<20$ kpc. The Young Halo GCs do not show significant anisotropy.",1803.04770v1
+2018-03-31,Understanding current-driven dynamics of magnetic Néel walls in heavy metal/ferromagnetic metal/oxide trilayers,"We consider analytically current-driven dynamics of magnetic N\'{e}el walls
+in heavy metal/ferromagnetic metal/oxide trilayers where strong spin-orbit
+coupling and interfacial Dzyaloshinskii-Moriya interaction (i-DMI) coexist. We
+show that field-like spin-orbit torque (FL-SOT) with effective field along
+$\mathbf{n}\times\hat{\mathbf{J}}$ ($\mathbf{n}$ being the interface normal and
+$\hat{\mathbf{J}}$ being the charge current direction) and i-DMI induced torque
+can both lead to Walker breakdown suppression meanwhile leaving the wall
+mobility (velocity versus current density) unchanged. However, i-DMI itself can
+not induce the ""universal absence of Walker breakdown"" (UAWB) while FL-SOT
+exceeding a certain threshold can. Finitely-enlarged Walker limits before UAWB
+are theoretically calculated and well explain existing data. In addition,
+change in wall mobility and even its sign-inversion can be understood only if
+the anti-damping-like (ADL) SOT is appended. For N\'{e}el walls in
+ferromagnetic-metal layer with both perpendicular and in-plane anisotropies, we
+have calculated the respective modifications of wall mobility under the
+coexistence of spin-transfer torque, SOTs and i-DMI. Analytics shows that in
+trilayers with perpendicular anisotropy strong enough spin Hall angle and
+appropriate sign of i-DMI parameter can lead to sign-inversion in wall mobility
+even under small enough current density, while in those with in-plane
+anisotropy this only occurs for current density in a specific range.",1804.00127v4
+2018-04-03,Influence of Exchange Scattering on Superfluid He-3 states in Nematic Aerogel,"The superfluid state in bulk liquid $^3$He is realized in the form of A or B
+phases. Uniaxially anisotropic aerogel (nafen) stabilizes transition from the
+normal to the polar superfluid state which on further cooling transitions to
+the axipolar orbital glass state (Phys. Rev. Lett. {\bf 115}, 165304 (2015)).
+This is the case in nafen aerogel preplated by several atomic layers of $^4$He.
+When pure liquid $^3$He fills the same nafen aerogel a solid-like layer of
+$^3$He atoms coats the aerogel structure. The polar state is not formed anymore
+and a phase transition occurs directly to the axipolar phase (Phys. Rev. Lett.
+{\bf 120}, 075301 (2018). The substitution of $^4$He by $^3$He atoms at the
+aerogel surface changes the potential and adds the exchange scattering of
+quasiparticles on the aerogel strands. A calculation shows that both of these
+effects can decrease the degree of anisotropy of scattering and suppress the
+polar phase formation. The derived anisotropy of the spin diffusion coefficient
+in globally anisotropic aerogel is determined by the same parameter which
+controls the polar state emergence which allows one to check the effect of
+anisotropy change for different types of covering.",1804.01073v3
+2018-04-25,Determination of the spin-lifetime anisotropy in graphene using oblique spin precession,"We determine the spin-lifetime anisotropy of spin-polarized carriers in
+graphene. In contrast to prior approaches, our method does not require large
+out-of-plane magnetic fields and thus it is reliable for both low- and
+high-carrier densities. We first determine the in-plane spin lifetime by
+conventional spin precession measurements with magnetic fields perpendicular to
+the graphene plane. Then, to evaluate the out-of-plane spin lifetime, we
+implement spin precession measurements under oblique magnetic fields that
+generate an out-of-plane spin population. We find that the spin-lifetime
+anisotropy of graphene on silicon oxide is independent of carrier density and
+temperature down to 150 K, and much weaker than previously reported. Indeed,
+within the experimental uncertainty, the spin relaxation is isotropic.
+Altogether with the gate dependence of the spin lifetime, this indicates that
+the spin relaxation is driven by magnetic impurities or random spin-orbit or
+gauge fields.",1804.09556v1
+2018-04-30,Statistical anisotropies in temperature and polarization fluctuations from a scale-dependent trispectrum,"We study statistical anisotropies generated in the observed two-point
+function of the cosmic microwave background (CMB) fluctuations if the
+primordial statistics are non-Gaussian. Focusing on the dipole modulations of
+the anisotropies, we find that the hemispherical power asymmetry observed in
+the CMB temperature fluctuations can be modeled by a local-type trispectrum
+with amplitude $\tau_{\rm NL}(k_p=0.05~{\rm Mpc}^{-1}) \approx 2 \times 10^4$
+and a large red tilt $n\approx -0.68$. We numerically evaluate the non-Gaussian
+covariance of the modulation estimators for both temperature and E-mode
+polarization fluctuations and discuss the prospects of constraining the model
+using Planck satellite data. We then discuss other effects of the
+scale-dependent trispectrum that could be used to distinguish this scenario
+from other explanations of the power asymmetry: higher-order modulations of the
+two-point function and the non-Gaussian angular power spectrum covariance. As
+an important consequence of the non-Gaussian power spectrum covariance, we
+discuss how the CMB-inferred spectral index of primordial scalar fluctuations
+can be significantly biased in the presence of a scale-dependent local-type
+trispectrum.",1805.00037v2
+2018-05-01,Diagonal Nematicity in the Pseudogap Phase of HgBa$_2$CuO$_{4+δ}$,"The pseudogap phenomenon in cuprates is the most mysterious puzzle in the
+research of high-temperature superconductivity. In particular, whether the
+pseudogap is associated with a crossover or phase transition has been a
+long-standing controversial issue. The tetragonal cuprate
+HgBa$_2$CuO$_{4+\delta}$, with only one CuO$_2$ layer per primitive cell, is an
+ideal system to tackle this puzzle. Here, we measure the anisotropy of magnetic
+susceptibility within the CuO$_2$ plane with exceptionally high-precision
+magnetic torque experiments. Our key finding is that a distinct two-fold
+in-plane anisotropy sets in below the pseudogap temperature $T^*$, which
+provides thermodynamic evidence for a nematic phase transition with broken
+four-fold symmetry. Most surprisingly, the nematic director orients along the
+diagonal direction of the CuO$_2$ square lattice, in sharp contrast to the bond
+nematicity reported in various iron-based superconductors and double-layer
+YBa$_2$Cu$_3$O$_{6+\delta}$, where the anisotropy axis is along the Fe-Fe and
+Cu-O-Cu directions, respectively. Another remarkable feature is that the
+enhancement of the diagonal nematicity with decreasing temperature is
+suppressed around the temperature at which short-range charge-density-wave
+(CDW) formation occurs. This is in stark contrast to
+YBa$_2$Cu$_3$O$_{6+\delta}$, where the bond nematicity is not influenced by the
+CDW. Our result suggests a competing relationship between diagonal nematic and
+CDW order in HgBa$_2$CuO$_{4+\delta}$.",1805.00276v1
+2018-05-12,Dissociation of heavy quarkonia in an anisotropic hot QCD medium in a Quasi-Particle Model,"The present article is the follow up work of, Phys.\ Rev.\ D {\bf 94}, 094006
+(2016), where we have extended the study of quarkonia dissociation in
+(momentum) anisotropic hot QCD medium. As evident by the experimentally
+observed collective flow at RHIC and LHC, the momentum anisotropy is present at
+almost all the stages after the collision and therefore, it is important to
+include its effects in the analysis. Employing the in-medium (corrected)
+potential while considering the anisotropy (both oblate and prolate cases) in
+the medium, the thermal widths and the binding energies of the heavy quarkonia
+states (s-wave charmonia and s-wave bottomonia specifically, for radial quantum
+numbers n = 1 and 2) have been determined. The hot QCD medium effects have been
+included employing a quasi-particle description. The presence of anisotropy has
+modified the potential and then the thermal widths and the binding energies of
+these states in a significant manner. The results show a quite visible shift in
+the values of dissociation temperatures as compared to the isotropic case.
+Further, the hot QCD medium interaction effects suppress the dissociation
+temperature as compared to the case where we consider the medium as a
+non-interacting ultra-relativistic gas of quarks (anti-quarks) and gluons.",1805.04763v1
+2018-05-21,Baryons under Strong Magnetic Fields or in Theories with Space-dependent $θ$-term,"Baryonic states are sufficiently complex to reveal physics that is hidden in
+the mesonic bound states. Using gauge/gravity correspondence we study
+analytically and numerically baryons in theories with space-dependent
+$\theta$-term, or theories under strong magnetic fields. Such holographic
+studies on baryons are accommodated in a generic analytic framework we develop
+for anisotropic theories, where their qualitative features are common
+irrespective of the source that triggers the anisotropy. We find that the
+distribution of the quarks forming the state, depends on the angle between the
+baryon and the anisotropic direction. Its shape is increasingly elliptic with
+respect to the strength of the field sourcing the anisotropy, counterbalancing
+the broken rotational invariance on the gluonic degrees of freedom. Strikingly,
+the baryons dissociate in stages with a process that depends on the proximity
+of the quarks to the anisotropic direction, where certain quark pairs abandon
+the bound state first, followed by the closest pairs to them as the temperature
+increases. This observation may also serve as a way to identify the nature of
+certain exotic states. Finally, we investigate holographic baryons with
+decreased number of quarks and explain why in theories under consideration the
+presence of anisotropy does not modify the universal stability condition in
+contrast to the usual trend.",1805.08245v2
+2018-05-22,Structural properties and anisotropic electronic transport in SrIrO3 films,"Perovskite SrIrO3 (SIO) films epitaxially deposited with a thickness of about
+60 nm on various substrate materials display nearly strain-relieved state.
+Films grown on orthorhombic (110) DyScO3 (DSO) are found to display untwinned
+bulk-like orthorhombic structure. However, film deposition on cubic (001)
+SrTiO3 induces a twinned growth of SIO. Resistance measurements on the SIO
+films reveal only weak temperature dependence, where the resistance R increases
+with decreasing temperature T. Hall measurements show dominant electron-like
+transport throughout the temperature range from 2 K to 300 K. At 2 K, the
+electron concentration and resistivity for SIO on STO amount to ne = 1.4*10^20
+cm-3 and 1 mohmcm. Interestingly, the film resistance of untwinned SIO on DSO
+along the [1-10] and the [001] direction differs by up to 25% indicating
+pronounced anisotropic electronic transport. The anisotropy of the resistance
+increases with decreasing T and displays a distinct maximum around 86 K. The
+specific T-dependence is similar to that of the structural anisotropy
+sqrt(a2+b2)/c of bulk SIO. Therefore, anisotropic electronic transport in SIO
+is very likely induced by the orthorhombic distortion. Consequently, for
+twinned SIO films on STO anisotropy vanishes nearly completely. The
+experimental results show that structural changes are very likely responsible
+for the observed anisotropic electronic transport. The strong sensitivity of
+the electronic transport in SIO films may be explained in terms of the narrow
+electron-like bands in SIO caused by spin-orbit-coupling and orthorhombic
+distortion.",1805.08473v2
+2018-06-05,Bilayer Kitaev models: Phase diagrams and novel phases,"Kitaev's honeycomb-lattice spin-$1/2$ model has become a paradigmatic example
+for $\mathbb{Z}_2$ quantum spin liquids, both gapped and gapless. Here we study
+the fate of these spin-liquid phases in differently stacked bilayer versions of
+the Kitaev model. Increasing the ratio between the inter-layer Heisenberg
+coupling $J_\perp$ and the intra-layer Kitaev couplings $K^{x,y,z}$ destroys
+the topological spin liquid in favor of a paramagnetic dimer phase. We study
+phase diagrams as a function of $J_\perp/K$ and Kitaev coupling anisotropies
+using Majorana-fermion mean-field theory, and we employ different expansion
+techniques in the limits of small and large $J_\perp/K$. For strongly
+anisotropic Kitaev couplings, we derive effective models for the different
+layer stackings which we use to discuss the quantum phase transition out of the
+Kitaev phase. We find that the phase diagrams depend sensitively on the nature
+of the stacking and anisotropy strength. While in some stackings and at strong
+anisotropies we find a single transition between the Kitaev and dimer phases,
+other stackings are more involved: Most importantly, we prove the existence of
+two novel macro-spin phases which can be understood in terms of Ising chains
+which can be either coupled ferromagnetically or remain degenerate, thus
+realizing a classical spin liquid. In addition, our results suggest the
+existence of a flux phase with spontaneous inter-layer coherence.",1806.01852v2
+2018-06-13,Evolution from Ferromagnetism to Antiferromagnetism in Yb(Rh1-xCox)2Si2,"Yb(Rh1-xCox)2Si2 is a model system to address two challenging problems in the
+field of strongly correlated electron systems: The first is the intriguing
+competition between ferromagnetic (FM) and antiferromagnetic (AFM) order when
+approaching a magnetic quantum critical point (QCP). The second is the
+occurrence of magnetic order along a very hard crystalline electric field (CEF)
+direction, i.e. along the one with the smallest available magnetic moment.
+Here, we present a detailed study of the evolution of the magnetic order in
+this system from a FM state with moments along the very hard c direction at x =
+0.27 towards the yet unknown magnetic state at x = 0. We first observe a
+transition towards an AFM canted state with decreasing x and then to a pure AFM
+state. This confirms that the QCP in YbRh2Si2 is AFM, but the phase diagram is
+very similar to those observed in some inherently FM systems like NbFe2 and
+CeRuPO, which suggests that the basic underlying instability might be FM.
+Despite the huge CEF anisotropy the ordered moment retains a component along
+the c-axis also in the AFM state. The huge CEF anisotropy in Yb(Rh1-xCox)2Si2
+excludes that this hard-axis ordering originates from a competing exchange
+anisotropy as often proposed for other heavy-fermion systems. Instead, it
+points to an order-by-disorder based mechanism.",1806.05088v2
+2018-06-29,Certain developments on the equilibrium of magnetized plasmas,"Recent results will be presented on steady states of magnetically confined
+plasmas obtained by conventional and Hamiltonian methods. The presentation
+consists of three parts. The first one concerns the derivation of a generalized
+Grad-Shafranov equation describing helically symmetric equilibria with pressure
+anisotropy and incompressible plasma flow of arbitrary direction with
+application to straight-stellarator configurations [1]. The impact of pressure
+anisotropy and flow on the equilibrium characteristics is also examined. In the
+second part the axisymmetric equilibrium code HELENA is extended for pressure
+anisotropy and flow parallel to the magnetic field and ITER-pertinent
+equilibria are constructed. In the third part the Hamiltonian formulation of
+helically symmetric plasmas is established within the framework of extended
+MHD, a simplified two-fluid model including Hall-ion and electron-inertia
+contributions [2,3]. Four families of Casimir invariants are obtained and they
+are used to construct Energy-Casimir variational principles for deriving
+generalized extended MHD equilibrium equations with arbitrary flow. The system
+is then cast into the form of Grad-Shafranov-Bernoulli equations. In addition,
+an example of an incompressible double-Beltrami equilibrium will be presented
+in connection with a straight-stellarator configuration.",1806.11343v2
+2018-07-04,Towards a Generalized Hydrodynamics description of Rényi entropies in integrable systems,"We investigate the steady-state R\'enyi entanglement entropies after a quench
+from a piecewise homogeneous initial state in integrable models. In the quench
+protocol two macroscopically different chains (leads) are joined together at
+the initial time, and the subsequent dynamics is studied. We study the
+entropies of a finite subsystem at the interface between the two leads. The
+density of R\'enyi entropies coincides with that of the entropies of the
+Generalized Gibbs Ensemble (GGE) that describes the interface between the
+chains. By combining the Generalized Hydrodynamics (GHD) treatment of the
+quench with the Bethe ansatz approach for the R\'enyi entropies, we provide
+exact results for quenches from several initial states in the anisotropic
+Heisenberg chain (XXZ chain), although the approach is applicable, in
+principle, to any low-entangled initial state and any integrable model. An
+interesting protocol that we consider is the expansion quench, in which one of
+the two leads is prepared in the vacuum of the model excitations. An intriguing
+feature is that for moderately large anisotropy the transport of bound-state is
+not allowed. Moreover, we show that there is a `critical' anisotropy, above
+which bound-state transport is permitted. This is reflected in the steady-state
+entropies, which for large enough anisotropy do not contain information about
+the bound states. Finally, we benchmark our results against time-dependent
+Density Matrix Renormalization Group (tDMRG) simulations.",1807.01800v2
+2018-07-19,Magnetization nutation induced by surface effects in nanomagnets,"We investigate the magnetization dynamics of ferromagnetic nanoparticles in
+the atomistic approach taking account of surface anisotropy and the spin
+misalignment it causes. We demonstrate that such inhomogeneous spin
+configurations induce nutation in the dynamics of the particle's magnetization.
+More precisely, in addition to the ordinary precessional motion with frequency
+$f_{p}\sim10\,{\rm GHz}$, we find that the dynamics of the net magnetic moment
+exhibits two more resonance peaks with frequencies $f_{c}$ and $f_{n}$ which
+are higher than the frequency $f_{p} : f_{c}=4\times f_{p}\sim40\,{\rm GHz}$ is
+related with the oscillations of the particle's magnetic moment between the
+minima of the effective potential induced by weak surface anisotropy. On the
+other hand, the much higher frequency $f_{n}\sim1\,{\rm THz}$ is attributed to
+the magnetization fluctuations at the atomic level driven by exchange
+interaction. We have compared our results on nutation induced by surface
+effects with those rendered by the macroscopic approach based on the
+Landau-Lifshitz-Gilbert equation augmented by an inertial term (proportional to
+the second-order time derivative of the macroscopic moment) with a
+phenomenological coefficient. The good agreement between the two models have
+allowed us to estimate the latter coefficient in terms of the atomistic
+parameters such as the surface anisotropy constant. We have thus proposed a new
+origin for the magnetization nutations as being induced by surface effects and
+have interpreted the corresponding resonance peaks and their frequencies.",1807.07392v1
+2018-07-20,Schwarzschild dynamical model of the Fornax dwarf spheroidal galaxy,"We present a full dynamical model of the Fornax dwarf spheroidal galaxy
+obtained with the spherically symmetric Schwarzschild orbit superposition
+method applied to the largest kinematic data set presently available. We
+modelled the total mass content of the dwarf with the mass-to-light ratio
+$\Upsilon$ varying with radius and found that Fornax is with high probability
+embedded in a massive and extended dark matter halo. We estimated the total
+mass contained within 1$\,$kpc to be $M(<1\,$kpc$)=1.25^{+0.06}_{-0.13} \times
+10^8\,$M$_{\odot}$. The data are consistent with the constant mass-to-light
+ratio, i.e. the mass-follows-light model, only at 3$\sigma$ level, but still
+require a high value of $\Upsilon \approx 11.2\,$M$_{\odot}/$L$_{\odot}$. Our
+results are in general agreement with previous estimates of the dynamical mass
+profile of Fornax. As the Schwarzschild method does not require any assumptions
+on the orbital anisotropy of the stars, we obtained a profile of the anisotropy
+parameter $\beta$ as an output of our modelling. The derived anisotropy is
+close to zero in the centre of the galaxy and decreases with radius, but
+remains consistent with isotropic orbits at all radii at 1$\sigma$ confidence
+level.",1807.07852v2
+2018-07-26,Modeling anisotropic magnetized White Dwarfs with $γ$ metric,"The effect of magnetic fields in the Equations of State (EoS) of compact
+objects is the splitting of the pressure in two components, one parallel and
+the other perpendicular to the magnetic field. This anisotropy suggests the
+necessity of using structure equations considering the axial symmetry of the
+magnetized system. In this work, we consider an axially symmetric metric in
+spherical coordinates, the $\gamma$-metric, and construct a system of equations
+to describe the structure of spheroidal compact objects. In addition, we
+connect the geometrical parameter $\gamma$ linked to the spheroid's radii, with
+the source of the anisotropy. So, the model relates the shape of the compact
+object to the physics that determines the properties of the composing matter.
+To illustrate how our structure equations work, we obtain the mass-radii
+solutions for magnetized White Dwarfs. Our results show that the main effect of
+the magnetic field anisotropy in White Dwarfs structure is to cause a
+deformation of these objects. Since this effect is only relevant at low
+densities, it does not affect the maximum values of magnetized White Dwarf's
+masses, which remain under Chandrasekhar limit.",1807.09943v3
+2018-08-04,The magnetic exchange parameters and anisotropy of the quasi-two dimensional antiferromagnet NiPS$_3$,"Neutron inelastic scattering has been used to measure the magnetic
+excitations in powdered NiPS$_3$, a quasi-two dimensional antiferromagnet with
+spin $S = 1$ on a honeycomb lattice. The spectra show clear, dispersive magnons
+with a $\sim 7$ meV gap at the Brillouin zone center. The data were fitted
+using a Heisenberg Hamiltonian with a single-ion anisotropy assuming no
+magnetic exchange between the honeycomb planes. Magnetic exchange interactions
+up to the third intraplanar nearest-neighbour were required. The fits show
+robustly that NiPS$_3$ has an easy axis anisotropy with $\Delta = 0.3$ meV and
+that the third nearest-neighbour has a strong antiferromagnetic exchange of
+$J_3 = -6.90$ meV. The data can be fitted reasonably well with either $J_1 < 0$
+or $J_1 > 0$, however the best quantitative agreement with high-resolution data
+indicate that the nearest-neighbour interaction is ferromagnetic with $J_1 =
+1.9$ meV and that the second nearest-neighbour exchange is small and
+antiferromagnetic with $J_2 = -0.1$ meV. The dispersion has a minimum in the
+Brillouin zone corner that is slightly larger than that at the Brillouin zone
+center, indicating that the magnetic structure of NiPS$_3$ is close to being
+unstable.",1808.01480v1
+2018-08-12,Measurement of the azimuthal anisotropy of charged particles produced in $\sqrt{s_\mathrm{NN}} = 5.02$ TeV Pb+Pb collisions with the ATLAS detector,"Measurements of the azimuthal anisotropy in lead-lead collisions at
+$\sqrt{s_\mathrm{NN}} = 5.02$ TeV are presented using a data sample
+corresponding to 0.49 $\mathrm{nb}^{-1}$ integrated luminosity collected by the
+ATLAS experiment at the LHC in 2015. The recorded minimum-bias sample is
+enhanced by triggers for ""ultra-central"" collisions, providing an opportunity
+to perform detailed study of flow harmonics in the regime where the initial
+state is dominated by fluctuations. The anisotropy of the charged-particle
+azimuthal angle distributions is characterized by the Fourier coefficients,
+$v_{2}-v_{7}$, which are measured using the two-particle correlation,
+scalar-product and event-plane methods. The goal of the paper is to provide
+measurements of the differential as well as integrated flow harmonics $v_{n}$
+over wide ranges of the transverse momentum, 0.5 $<p_{\mathrm{T}}<$ 60 GeV, the
+pseudorapidity, $|\eta|<$ 2.5, and the collision centrality $0-80$%. Results
+from different methods are compared and discussed in the context of previous
+and recent measurements in Pb+Pb collisions at $\sqrt{s_\mathrm{NN}} = 2.76$
+TeV and 5.02 TeV. In particular, the shape of the $p_{\mathrm{T}}$ dependence
+of elliptic or triangular flow harmonics is observed to be very similar at
+different centralities after scaling the $v_{n}$ and $p_{\mathrm{T}}$ values by
+constant factors over the centrality interval $0-60$% and the $p_{\mathrm{T}}$
+range $0.5 < p_{\mathrm{T}} < 5$ GeV.",1808.03951v2
+2018-08-20,Breaking properties of neutron star crust,"The strength of neutron star crust is crucial for modelling magnetar flares,
+pulsar glitches and gravitational wave emission. We aim to shed some light on
+this problem by analysing uniaxial stretch deformation (elongation and
+contraction) of perfect body-centered cubic Coulomb crystals, paying special
+attention to the inherent anisotropy of this process. Our analysis is based on
+the semi-analytical approach of Baiko and Kozhberov (2017), which, for any
+uniform deformation, allows one to calculate, in fully non-linear regime,
+critical deformation parameters beyond which the lattice loses its dynamic
+stability. We determine critical strain, pressure anisotropy and deformation
+energy for any stretch direction with respect to the crystallographic axes.
+These quantities are shown to be strongly anisotropic: they vary by a factor of
+almost 10 depending on the orientation of the deformation axis. For
+polycrystalline crust, we argue that the maximum strain for the stretch
+deformation sustainable elastically is 0.04. It is lower than the breaking
+strain of 0.1 obtained in molecular dynamic simulations of a shear deformation
+by Horowitz and Kadau (2009). The maximum pressure anisotropy of
+polycrystalline matter is estimated to be in the range from 0.005 to 0.014
+$nZ^2e^2/a$, where $n$ is the ion number density, $Ze$ is the ion charge, and
+$a$ is the ion-sphere radius. We discuss possible mechanisms of plastic motion
+and formation of large crystallites in neutron star crust as well as analyse
+energy release associated with breaking of such crystallites in the context of
+magnetic field evolution and magnetar flaring activity.",1808.06415v1
+2018-09-03,Dynamics of a simple model microswimmer in an anisotropic fluid: implications for alignment behavior and active transport in a nematic liquid crystal,"Several recent experiments investigate the orientational and transport
+behavior of self-driven bacteria and colloidal particles in nematic liquid
+crystals. Correspondingly, we study theoretically the dynamics of a minimal
+model microswimmer in a uniaxially anisotropic fluid. As a first step, the
+hydrodynamic Green's function providing the resulting fluid flow in response to
+a localized force acting on the anisotropic fluid is derived analytically. On
+this basis, the behavior of both puller- and pusher-type microswimmers in the
+anisotropic fluid is analyzed. Depending on the propulsion mechanism and the
+relative magnitude of different involved viscosities, we find alignment of the
+swimmers parallel or perpendicular to the anisotropy axis. Particularly, also
+an oblique alignment is identified under certain circumstances. The observed
+swimmer reorientation results from the hydrodynamic coupling between the
+self-induced fluid flow and the anisotropy of the surrounding fluid, which
+distorts the self-generated flow field. We support parts of our results by a
+simplified linear stability analysis. Our theoretical predictions are in
+qualitative agreement with recent experimental observations on swimming
+bacteria in nematic liquid crystals. They support the objective of utilizing
+the, possibly switchable, anisotropy of a host fluid to guide individual
+microswimmers and active particles along a requested path, enabling controlled
+active transport.",1809.01531v1
+2018-09-12,Strong Anisotropy in Liquid Water upon Librational Excitation using Terahertz Laser Fields,"Tracking the excitation of water molecules in the homogeneous liquid is
+challenging due to the ultrafast dissipation of rotational excitation energy
+through the hydrogen-bonded network. Here we demonstrate strong transient
+anisotropy of liquid water through librational excitation using single-color
+pump-probe experiments at 12.3 THz. We deduce a third order response of chi^3
+exceeding previously reported values in the optical range by three orders of
+magnitude. Using a theory that replaces the nonlinear response with a material
+response property amenable to molecular dynamics simulation, we show that the
+rotationally damped motion of water molecules in the librational band is
+resonantly driven at this frequency, which could explain the enhancement of the
+anisotropy in the liquid by the external Terahertz field. By addition of salt
+(MgSO4), the hydration water is instead dominated by the local electric field
+of the ions, resulting in reduction of water molecules that can be dynamically
+perturbed by THz pulses.",1809.04261v3
+2018-09-21,Minimal Paths for Tubular Structure Segmentation with Coherence Penalty and Adaptive Anisotropy,"The minimal path method has proven to be particularly useful and efficient in
+tubular structure segmentation applications. In this paper, we propose a new
+minimal path model associated with a dynamic Riemannian metric embedded with an
+appearance feature coherence penalty and an adaptive anisotropy enhancement
+term. The features that characterize the appearance and anisotropy properties
+of a tubular structure are extracted through the associated orientation score.
+The proposed dynamic Riemannian metric is updated in the course of the geodesic
+distance computation carried out by the efficient single-pass fast marching
+method. Compared to state-of-the-art minimal path models, the proposed minimal
+path model is able to extract the desired tubular structures from a complicated
+vessel tree structure. In addition, we propose an efficient prior path-based
+method to search for vessel radius value at each centerline position of the
+target. Finally, we perform the numerical experiments on both synthetic and
+real images. The quantitive validation is carried out on retinal vessel images.
+The results indicate that the proposed model indeed achieves a promising
+performance.",1809.07987v4
+2018-09-24,"Strain-tunable magnetic anisotropy in monolayer CrCl$_3$, CrBr$_3$, and CrI$_3$","Recent observation of intrinsic ferromagnetism in two-dimensional (2D)
+CrI$_3$ is associated with the large magnetic anisotropy due to strong
+spin-orbit coupling (SOC) of I. Magnetic anisotropy energy (MAE) defines the
+stability of magnetization in a specific direction with respect to the crystal
+lattice and is an important parameter for nanoscale applications. In this work
+we apply the density functional theory to study the strain dependence of MAE in
+2D monolayer chromium trihalides CrX$_3$ (with X = Cl, Br, and I). Detailed
+calculations of their energetics, atomic structures and electronic structures
+under the influence of a biaxial strain $\varepsilon$ have been carried out. It
+is found that all three compounds exhibit ferromagnetic ordering at the ground
+state (with $\varepsilon$=0) and upon applying a compressive strain, phase
+transition to antiferromagnetic state occurs. Unlike in CrCl$_3$ and CrBr$_3$,
+the electronic band gap in CrI$_3$ increases when a tensile strain is applied.
+The MAE also exhibits a strain dependence in the chromium trihalides: it
+increases when a compressive strain is applied in CrI$_3$, while an opposite
+trend is observed in the other two compounds. In particular, the MAE of CrI$_3$
+can be increased by 47\% with a compressive strain of $\varepsilon$ = 5\%.",1809.08725v1
+2018-10-22,Anisotropic Charge Distribution Induced by Spin Polarization in La$_{0.6}$Sr$_{0.4}$MnO$_{3}$ Thin Films Studied by X-ray Magnetic Linear Dichroism,"Magnetic anisotropy of epitaxially grown thin films is affected by the strain
+from the substrates due to a combined effect of distorted electronic structure
+and spin-orbit interaction (SOI). As an inverse process, one expects an
+anisotropy of the electronic structure induced by magnetization in the presence
+of SOI. We have studied the charge-density anisotropy induced by magnetization
+in thin films of the ferromagnetic metal La$_{1-x}$Sr$_{x}$MnO$_3$ via x-ray
+magnetic linear dichroism (XMLD). XMLD measurements on thin films with various
+thicknesses have shown that the XMLD intensity is proportional to the square of
+the ferromagnetic moment. Using the XMLD sum rule and cluster-model
+calculation, it has been shown that more Mn 3$d$ electrons are distributed in
+orbitals elongated along the direction parallel to the spin polarization than
+in orbitals elongated in the direction perpendicular to it. The cluster-model
+calculation has shown that the effect of tensile strain from the SrTiO$_3$
+substrate on the XMLD spectra is also consistent with the observed XMLD
+spectral line shapes.",1810.09077v1
+2018-10-27,Fast determination of coarse grained cell anisotropy and size in epithelial tissue images using Fourier transform,"Mechanical strain and stress play a major role in biological processes such
+as wound healing or morphogenesis. To assess this role quantitatively, fixed or
+live images of tissues are acquired at a cellular precision in large fields of
+views. To exploit these data, large numbers of cells have to be analyzed to
+extract cell shape anisotropy and cell size. Most frequently, this is performed
+through detailed individual cell contour determination, using so-called
+segmentation computer programs, complemented if necessary by manual detection
+and error corrections. However, a coarse grained and faster technique can be
+recommended in at least three situations. First, when detailed information on
+individual cell contours is not required, for instance in studies which require
+only coarse-grained average information on cell anisotropy. Second, as an
+exploratory step to determine whether full segmentation can be potentially
+useful. Third, when segmentation is too difficult, for instance due to poor
+image quality or too large a cell number. We developed a user-friendly, Fourier
+transform-based image analysis pipeline. It is fast (typically $10^4$ cells per
+minute with a current laptop computer) and suitable for time, space or ensemble
+averages. We validate it on one set of artificial images and on two sets of
+fully segmented images, one from a Drosophila pupa and the other from a chicken
+embryo; the pipeline results are robust. Perspectives include \textit{in vitro}
+tissues, non-biological cellular patterns such as foams, and $xyz$ stacks.",1810.11652v3
+2018-11-14,Giant anisotropy in superconducting single crystals of CsCa$_2$Fe$_4$As$_4$F$_2$,"CsCa$_2$Fe$_4$As$_4$F$_2$ is a newly discovered iron-based superconductor
+with $T_\mathrm{c}\sim$ 30 K containing double Fe$_2$As$_2$ layers that are
+separated by insulating Ca$_2$F$_2$ spacer layers. Here we report the transport
+and magnetization measurements on CsCa$_2$Fe$_4$As$_4$F$_2$ single crystals
+grown for the first time using the self flux of CsAs. We observed a huge
+resistivity anisotropy $\rho_c(T)/\rho_{ab}(T)$, which increases with
+decreasing temperature, from 750 at 300 K to 3150 at 32 K. The $\rho_c(T)$ data
+exhibit a non-metallic behavior above $\sim$140 K, suggesting an incoherent
+electronic state at high temperatures due to the dimension crossover. The
+superconducting onset transition temperature in $\rho_{ab}$ is 0.7 K higher
+than that in $\rho_c$, suggesting two-dimensional (2D) superconducting
+fluctuations. The lower and upper critical fields also show an exceptional
+anisotropy among iron-based superconductors. The $H_{c1}^\bot(T)$ data are well
+fitted using the model with two $s$-wave-like superconducting gaps,
+$\Delta_1(0)=6.75$ meV and $\Delta_2(0)=2.32$ meV. The inter-plane coherence
+length $\xi_c(0)$ is $3.6$ \AA, remarkably smaller than the distance between
+conducting layers (8.6 \AA), consolidating the 2D nature in the title material.",1811.05706v1
+2018-11-19,Cosmologically viable generalized Einstein-Aether theories,"We investigate generalized Einstein-Aether theories that are compatible with
+the Planck Cosmic Microwave Background (CMB) temperature anisotropy,
+polarisation, and lensing data. For a given dark energy equation of state,
+$w_{\rm de}$, we formulate a designer approach and we investigate their impact
+on the CMB temperature anisotropy and matter power spectra. We use the Equation
+of State approach to parametrize the perturbations and find that this approach
+is particularly useful in identifying the most suitable and numerically
+efficient parameters to explore in a Markov chain Monte Carlo (MCMC) analysis.
+We find the data constrains models with $w_{\rm de} = -1$ to be compatible with
+$\Lambda$CDM. For $w_{\rm de} \not= -1$ models, which avoid the gravitational
+waves constraint through the entropy perturbation, we constrain $w_{\rm de}$ to
+be $w_{\rm de } = -1.06^{+0.08}_{-0.03}$ (CMB) and $w_{\rm de }
+=-1.04^{+0.05}_{-0.02}$ (CMB+Lensing) at $68\%$C.L., and find that these models
+can be different from $\Lambda$CDM and still be compatible with the data. We
+also find that these models can ameliorate some anomalies in $\Lambda$CDM when
+confronted with data, such as the low-$\ell$ and high-$k$ power in the CMB
+temperature anisotropy and matter power spectra respectively, but not
+simultaneously. We also investigate the anomalous lensing amplitude, quantified
+by $A_{\rm lens}$, and find that that for $w_{\rm de} = -1$ models, $A_{\rm
+lens} = 1.15^{+0.07}_{-0.08}$ (CMB) and $A_{\rm lens} = 1.12\pm0.05$
+(CMB+Lensing) at $68\%$C.L. $\sim$ 2$\sigma$ larger than expected, similar to
+previous analyses of $\Lambda$CDM.",1811.07805v1
+2018-12-10,Influence of strain and chemical substitution on the magnetic anisotropy of antiferromagnetic Cr$_2$O$_3$: an ab-initio study,"The influence of the mechanical strain and chemical substitution on the
+magnetic anisotropy energy (MAE) of Cr$_2$O$_3$ is studied using
+first-principles calculations. Dzyaloshinskii-Moriya interaction contributes
+substantially to MAE by inducing spin canting when the antiferromagnetic order
+parameter is not aligned with the hexagonal axis. Nearly cubic crystal field
+results in a very small MAE in pure Cr$_2$O$_3$ at zero strain, which is
+incorrectly predicted to be negative (in-plane) on account of spin canting. The
+MAE is strongly modified by epitaxial strain, which tunes the crystal-field
+splitting of the $t_{2g}$ triplet. The contribution from magnetic dipolar
+interaction is very small at any strain. The effects of cation (Al, Ti, V, Co,
+Fe, Nb, Zr, Mo) and anion (B) substitutions on MAE are examined. Al increases
+MAE thanks to the local lattice deformation. In contrast, the electronic
+configuration of V and Nb strongly promotes easy-plane anisotropy, while other
+transition-metal dopants have only a moderate effect on MAE. Substitution of
+oxygen by boron, which has been reported to increase the N\'eel temperature,
+has a weak effect on MAE, whose sign depends on the charge state of B. The
+electric field applied along the (0001) axis has a weak second-order effect on
+the MAE.",1812.04060v1
+2018-12-12,Quasilinear Consequences of Turbulent Ion Heating by Magnetic Moment Breaking,"The fast solar wind emerging from coronal holes is likely heated and
+accelerated by the dissipation of magnetohydrodynamic turbulence, but the
+specific kinetic mechanism resulting in the perpendicular ion heating required
+by observations is not understood. A promising mechanism has been proposed by
+Chandran et al. (2010), which in this paper we call ""magnetic moment breaking""
+(MMB). As currently formulated, MMB dissipation operates only on the ion
+perpendicular motion, and does not influence their parallel temperature. Thus,
+the MMB mechanism acting by itself produces coronal hole proton distributions
+that are unstable to the ion-cyclotron anisotropy instability. This quasilinear
+instability is expected to operate faster than the nonlinear turbulent cascade,
+scattering ions into the parallel direction and generating
+quasi-parallel-propagating ion-cyclotron (IC) waves. To investigate the
+consequences of this instability on the MMB-heated protons, we construct a
+homogeneous model for protons with coronal hole properties. Using a simplified
+version of the resonant cyclotron interaction, we heat the protons by the MMB
+process and instantaneously scatter them to lower anisotropy while
+self-consistently generating parallel-propagating IC waves. We present several
+illustrative cases, finding that the extreme anisotropies implied by the MMB
+mechanism are limited to reasonable values, but the distinctive shape of the
+proton distribution derived by Klein & Chandran (2016) is not maintained. We
+also find that these combined processes can result in somewhat higher particle
+energization than the MMB heating alone. These quasilinear consequences should
+follow from any kinetic mechanism that primarily increases the perpendicular
+ion temperature in a collisionless plasma.",1812.05021v1
+2018-12-19,Interfacial Spin-Orbit Coupling: New Platform for Superconducting Spintronics,"Spin-orbit coupling (SOC) is a key interaction in spintronics, allowing an
+electrical control of spin or magnetization and, vice versa, a magnetic control
+of electrical current. However, recent advances have revealed much broader
+implications of SOC that is also central to the design of topological states,
+including topological insulators, skyrmions, and Majorana fermions, or to
+overcome the exclusion of two-dimensional ferro-magnetism expected from the
+Mermin-Wagner theorem. SOC and the resulting emergent interfacial spin-orbit
+fields are simply realized in junctions through structural inversion asymmetry,
+while the anisotropy in magnetoresistance (MR) allows for their experimental
+detection. Surprisingly, we demonstrate that an all-epitaxial
+ferromagnet/MgO/metal junction with only a negligible MR anisotropy undergoes a
+remarkable transformation below the superconducting transition temperature of
+the metal. The superconducting junction has a three orders of magnitude higher
+MR anisotropy and supports the formation of spin-triplet superconductivity,
+crucial for superconducting spintronics, and topologically-protected quantum
+computing. Our findings call for revisiting the role of SOC in other systems
+which, even when it seems negligible in the normal state, could have a profound
+influence on the superconducting response.",1812.08090v2
+2018-12-26,Discretized dynamics of exchange spin wave bulk and edge modes in honeycomb nanoribbons with armchair edge boundaries,"We develop a field theory to study the dynamics of long wavelength exchange
+spin wave excitations on honeycomb nanoribbons characterized by armchair edge
+boundaries and the N\'eel antiferromagnetic ordering state. Appropriate
+boundary conditions are established by requiring that the bulk and edge spins
+precess with the same frequency for any given spin wave eigenmode in these
+systems. A set of characteristic boundary equations, common for bulk and edge
+spin wave modes, are hence derived. The equations of motion for the spin
+dynamics are then solved to determine the propagating and evanescent exchange
+spin wave modes. We prove in general that the bulk spin wave dynamics is
+discretized due to the finite width of the nanoribbon. For an isotropic
+magnetic nanoribbon, the Dirac cone is reduced to a single linear dispersion
+curve due to this discretization. The number and wavelengths of allowed bulk
+modes for isotropic and anisotropic nanoribbons are determined from the derived
+characteristic boundary equations. As witnessed by our numerical results for
+different examples it is shown that the characteristics of these modes depend
+on the width of the nanoribbon and its antiferromagnetic anisotropy. Further,
+anisotropic nanoribbons, even those with the slightest anisotropy, present
+evanescent modes with non-linear dispersion relations. The spatial variation of
+the amplitudes of the evanescent exchange spin waves across the finite widths
+of the nanoribbons, is found to be strongly dependent on the system magnetic
+anisotropy and its width. The developed theoretical approach is general and can
+be applied for nanoribbons with all types of boundary edges.",1812.10204v2
+2018-12-31,Systematic Control of Strain-Induced Perpendicular Magnetic Anisotropy in Epitaxial Europium and Terbium Iron Garnets Thin Films,"We show tunable strain-induced perpendicular magnetic anisotropy (PMA) over a
+wide range of thicknesses in epitaxial ferrimagnetic insulator Eu3Fe5O12 (EuIG)
+and Tb3Fe5O12 (TbIG) thin films grown by pulsed-laser deposition on Gd3Ga5O12
+with (001) and (111) orientations, respectively. The PMA field is determined by
+measuring the induced anomalous Hall loops in Pt deposited on the garnet films.
+Due to positive magnetostriction constants, compressive in-plane strain induces
+a PMA field as large as 32.9 kOe for 4 nm thick EuIG and 66.7 kOe for 5 nm
+thick TbIG at 300 K, and relaxes extremely slowly as the garnet film thickness
+increases. In bilayers consisting of Pt and EuIG or Pt and TbIG, robust PMA is
+revealed by squared anomalous Hall hysteresis loops in Pt, the magnitude of
+which appears to be only related to the net magnetic moment of iron
+sublattices. Furthermore, the magnetostriction constant is found to be
+2.7x10^(-5) for EuIG and 1.35x10^(-5) for TbIG, comparable with the values for
+bulk crystals. Our results demonstrate a general approach of tailoring magnetic
+anisotropy of rare earth iron garnets by utilizing modulated strain via
+epitaxial growth.",1812.11688v1
+2019-01-17,Improved fibre dispersion estimation using b-tensor encoding,"Measuring fibre dispersion in white matter with diffusion magnetic resonance
+imaging (MRI) is limited by an inherent degeneracy between fibre dispersion and
+microscopic diffusion anisotropy (i.e., the diffusion anisotropy expected for a
+single fibre orientation). This means that estimates of fibre dispersion rely
+on strong assumptions, such as constant microscopic anisotropy throughout the
+white matter or specific biophysical models. Here we present a simple approach
+for resolving this degeneracy using measurements that combine linear
+(conventional) and spherical tensor diffusion encoding.
+  To test the accuracy of the fibre dispersion when our microstructural model
+is only an approximation of the true tissue structure, we simulate
+multi-compartment data and fit this with a single-compartment model. For such
+overly simplistic tissue assumptions, we show that the bias in fibre dispersion
+is greatly reduced ($\sim$5x) for single-shell linear and spherical tensor
+encoding data compared with single-shell or multi-shell conventional data. In
+in-vivo data we find a consistent estimate of fibre dispersion as we reduce the
+b-value from 3 to 1.5 ms/$\mu$m$^2$, increase the repetition time, increase the
+echo time, or increase the diffusion time. We conclude that the addition of
+spherical tensor encoded data to conventional linear tensor encoding data
+greatly reduces the sensitivity of the estimated fibre dispersion to the model
+assumptions of the tissue microstructure.",1901.05820v2
+2019-01-25,Dielectric Resonator Method For Determining Gap Symmetry Of Superconductors Through Anisotropic Nonlinear Meissner Effect,"We present a new measurement method which can be used to image gap nodal
+structure of superconductors whose pairing symmetry is under debate. This
+technique utilizes a high quality factor microwave resonance involving the
+sample of interest. While supporting a circularly symmetric standing wave
+current pattern, the sample is perturbed by a scanned laser beam, creating a
+photoresponse that was previously shown to reveal the superconducting gap
+anisotropy. Simulation and the measurement of the photoresponse of an
+unpatterned Nb film show less than 8\% anisotropy, as expected for a
+superconductor with nearly isotropic energy gap along with expected systematic
+uncertainty. On the other hand, measurement of a YBa$_2$Cu$_3$O$_{7-\delta}$
+thin film shows a clear 4-fold symmetric image with $\mathtt{\sim}12.5$\%
+anisotropy, indicating the well-known 4-fold symmetric $d_{x^2-y^2}$ gap nodal
+structure in the $ab$-plane. The deduced gap nodal structure can be further
+cross-checked by low temperature surface impedance data, which is
+simultaneously measured. The important advantage of the presented method over
+the previous spiral resonator method is that it does not require a complicated
+lithographic patterning process which limits one from testing various kinds of
+materials due to photoresponse arising from patterning defects. This advantage
+of the presented technique, and the ability to measure unpatterned samples such
+as planar thin films and single crystals, enables one to survey the pairing
+symmetry of a wide variety of unconventional superconductors.",1901.08762v2
+2019-01-29,Initial state description of azimuthally collimated long range correlations in ultrarelativistic light-heavy ion collisions,"It was argued in arXiv:1805.09342 and arXiv:1807.00825 that the systematics
+of the azimuthal anisotropy coefficients $v_{2,3}$ measured in
+ultrarelativistic light-heavy ion collisions at RHIC and the LHC can be
+described in an initial state dilute-dense Color Glass Condensate (CGC)
+framework. We elaborate here on the discussion in these papers and provide
+further novel results that strengthen their conclusions. The underlying
+mathematical framework and numerical techniques employed are very similar to
+those in the CGC based IP-Glasma model used previously as initial conditions
+for heavy-ion collisions. The uncertainties in theory/data comparisons for
+small systems are discussed, with unknowns that are specific to the model
+distinguished from those that are generic to all models. We present analytical
+arguments that demonstrate that quantum interference effects such as Bose
+enhancement and Hanbury-Brown-Twiss correlations of gluons, as well as coherent
+multiple scattering of gluons in the projectile off color domains in the
+target, are enhanced in rare events. The quantum origins of the large
+anisotropies in small systems are corroborated by numerical results for
+deuteron-gold collisions that show that large anisotropies in rare
+configurations can occur when the nucleons in the projectile overlap
+significantly. This is at variance with the classical intuition of
+hydrodynamical models. We also comment on the consequences of ignoring the
+many-body color charge correlations of gluons in models that only consider
+geometrical fluctuations in the energy density.",1901.10506v1
+2019-01-31,Fundamental Spin Interactions Underlying the Magnetic Anisotropy in the Kitaev Ferromagnet CrI$_3$,"We lay the foundation for determining the microscopic spin interactions in
+two-dimensional (2D) ferromagnets by combining angle-dependent ferromagnetic
+resonance (FMR) experiments on high quality CrI$_3$ single crystals with
+theoretical modeling based on symmetries. We discover that the Kitaev
+interaction is the strongest in this material with $K \sim -5.2$ meV, 25 times
+larger than the Heisenberg exchange $J \sim -0.2$ meV, and responsible for
+opening the $\sim$5 meV gap at the Dirac points in the spin-wave dispersion.
+Furthermore, we find that the symmetric off-diagonal anisotropy $\Gamma \sim
+-67.5$ $\mu$eV, though small, is crucial for opening a $\sim$0.3 meV gap in the
+magnon spectrum at the zone center and stabilizing ferromagnetism in the 2D
+limit. The high resolution of the FMR data further reveals a $\mu$eV-scale
+quadrupolar contribution to the $S=3/2$ magnetism. Our identification of the
+underlying exchange anisotropies opens paths toward 2D ferromagnets with higher
+$T_\text{C}$ as well as magnetically frustrated quantum spin liquids based on
+Kitaev physics.",1902.00077v2
+2019-02-06,Phase boundary anisotropy and its effects on the maze-to-lamellar transition in a directionally solidified Al-Al2Cu eutectic,"Solid-solid phase boundary anisotropy is a key factor controlling the
+selection and evolution of non-faceted eutectic patterns during directional
+solidification. This is most remarkably observed during the so-called
+maze-to-lamellar transition. By using serial sectioning, we followed the
+spatio-temporal evolution of a maze pattern over long times in a large Al-Al2Cu
+eutectic grain with known crystal orientation of the Al and Al2Cu phases, hence
+known crystal orientation relationship (OR). The corresponding phase boundary
+energy anisotropy ($\gamma$-plot) was also known, as being previously estimated
+from molecular-dynamics computations. The experimental observations reveal the
+time-scale of the maze-to-lamellar transition and shed light on the processes
+involved in the gradual alignment of the phase boundaries to one distinct
+energy minimum which nearly corresponds to one distinct plane from the family
+$\{120\}^{\rm{Al}} //\{110\}^{\rm{Al2Cu}}$. This particular plane is selected
+due to a crystallographic bias induced by a small disorientation of the
+crystals relative to the perfect OR. The symmetry of the OR is thus slightly
+broken, which promotes lamellar alignment. Finally, the maze-to-lamellar
+transition leaves behind a network of fault lines inherited from the phase
+boundary alignment process. In the maze pattern, the fault lines align along
+the corners of the Wulff shape, thus allowing us to propose a link between the
+pattern defects and missing orientations in the Wulff shape",1902.02210v1
+2019-02-06,Anisotropy induced vortex lattice rearrangement in CaKFe$_4$As$_4$,"The magnetic penetration depth anisotropy
+$\gamma_\lambda=\lambda_{c}/\lambda_{ab}$ ($\lambda_{ab}$ and $\lambda_{c}$ are
+the in-plane and the out-of-plane components of the magnetic penetration depth)
+in a CaKFe$_4$As$_4$ single crystal sample (the critical temperature $T_{\rm
+c}\simeq 35$ K) was studied by means of muon-spin rotation ($\mu$SR).
+$\gamma_\lambda$ is almost temperature independent for $T\lesssim 20$ K
+($\gamma_\lambda\simeq 1.9$) and it reaches $\simeq 3.0$ by approaching $T_{\rm
+c}$. The change of $\gamma_\lambda$ induces the corresponding rearrangement of
+the flux line lattice (FLL), which is clearly detected via enhanced distortions
+of the FLL $\mu$SR response. Comparison of $\gamma_\lambda$ with the anisotropy
+of the upper critical field ($\gamma_{H_{\rm c2}}$) studied in Phys. Rev B {\bf
+94}, 064501 (2016), reveals that $\gamma_\lambda$ is systematically higher than
+$\gamma_{H_{\rm c2}}$ at low-temperatures and approaches $\gamma_{H_{\rm c2}}$
+for $T \rightarrow T_{\rm c}$. The anisotropic properties of $\lambda$ are
+explained by the multi-gap nature of superconductivity in CaKFe$_4$As$_4$ and
+are caused by anisotropic contributions of various bands to the in-plane and
+the out-of-plane components of the superfluid density.",1902.02268v1
+2019-02-10,Cosmic Anisotropy and Fast Radio Bursts,"In the recent years, the field of fast radio bursts (FRBs) is thriving and
+growing rapidly. It is of interest to study cosmology by using FRBs with known
+redshifts. In the present work, we try to test the possible cosmic anisotropy
+with the simulated FRBs. In particular, we only consider the possible dipole in
+FRBs, rather than the cosmic anisotropy in general, while the analysis is only
+concerned with finding the rough number of necessary data points to distinguish
+a dipole from a monopole structure through simulations. Noting that there is no
+a large sample of actual data of FRBs with known redshifts by now, simulations
+are necessary to this end. We find that at least 2800, 190, 100 FRBs are
+competent to find the cosmic dipole with amplitude 0.01, 0.03, 0.05,
+respectively. Unfortunately, even 10000 FRBs are not competent to find the tiny
+cosmic dipole with amplitude of ${\cal O}(10^{-3})$. On the other hand, at
+least 20 FRBs with known redshifts are competent to find the cosmic dipole with
+amplitude 0.1. We expect that such a big cosmic dipole could be ruled out by
+using only a few tens of FRBs with known redshifts in the near future.",1902.03580v3
+2019-02-14,Calculating temperature-dependent properties of Nd$_2$Fe$_{14}$B permanent magnets by atomistic spin model simulations,"Temperature-dependent magnetic properties of Nd$_2$Fe$_{14}$B permanent
+magnets, i.e., saturation magnetization $M_\text{s}(T)$, effective magnetic
+anisotropy constants $K_i^\text{eff}(T)$ ($i=1,2,3$), domain wall width
+$\delta_w(T)$, and exchange stiffness constant $A_\text{e}(T)$, are calculated
+by using \textit{ab-initio} informed atomistic spin model simulations. We
+construct the atomistic spin model Hamiltonian for Nd$_2$Fe$_{14}$B by using
+the Heisenberg exchange of Fe$-$Fe and Fe$-$Nd atomic pairs, the uniaxial
+single-ion anisotropy of Fe atoms, and the crystal-field energy of Nd ions
+which is approximately expanded into an energy formula featured by second,
+fourth, and sixth-order phenomenological anisotropy constants. After applying a
+temperature rescaling strategy, we show that the calculated Curie temperature,
+spin-reorientation phenomenon, $M_\text{s}(T)$, $\delta_w(T)$, and
+$K_i^\text{eff}(T)$ agree well with the experimental results. $A_\text{e}(T)$
+is estimated through a general continuum description of the domain wall profile
+by mapping atomistic magnetic moments to the macroscopic magnetization.
+$A_\text{e}$ is found to decrease more slowly than $K_1^\text{eff}$ with
+increasing temperature, and approximately scale with normalized magnetization
+as $A_\text{e}(T) \sim m^{1.2}$. This work provokes a scale bridge between
+\textit{ab-initio} calculations and temperature-dependent micromagnetic
+simulations of Nd-Fe-B permanent magnets.",1902.05636v2
+2019-02-25,Mapping the stability of stellar rotating spheres via linear response theory,"Rotation is ubiquitous in the Universe, and recent kinematic surveys have
+shown that early type galaxies and globular clusters are no exception. Yet the
+linear response of spheroidal rotating stellar systems has seldom been studied.
+This paper takes a step in this direction by considering the behaviour of
+spherically symmetric systems with differential rotation. Specifically, the
+stability of several sequences of Plummer spheres is investigated, in which the
+total angular momentum, as well as the degree and flavour of anisotropy in the
+velocity space are varied. To that end, the response matrix method is
+customised to spherical rotating equilibria. The shapes, pattern speeds and
+growth rates of the systems' unstable modes are computed. Detailed comparisons
+to appropriate N-body measurements are also presented. The marginal stability
+boundary is charted in the parameter space of velocity anisotropy and rotation
+rate. When rotation is introduced, two sequences of growing modes are
+identified corresponding to radially and tangentially-biased anisotropic
+spheres respectively. For radially anisotropic spheres, growing modes occur on
+two intersecting surfaces (in the parameter space of anisotropy and rotation),
+which correspond to fast and slow modes, depending on the net rotation rate.
+Generalised, approximate stability criteria are finally presented.",1902.09299v1
+2019-02-25,Strong anisotropy in the mixed antiferromagnetic system Mn$_{1-x}$Fe$_{x}$PSe$_3$,"We report the magnetic phase diagram of Mn$_{1-x}$Fe$_{x}$PSe$_3$ which
+represents a random magnet system of two antiferromagnetic systems with mixed
+spin, mixed spin anisotropies, mixed nearest neighbor magnetic interactions and
+mixed periodicities in their respective antiferromagnetic structure. Bulk
+samples of Mn$_{1-x}$Fe$_{x}$PSe$_3$ have been prepared and characterized phase
+pure by powder X-ray and neutron diffraction and X-ray fluorescence. Nature and
+extent of magnetically ordered state has been established using powder neutron
+diffraction, dc magnetic susceptibility and heat capacity. Long-range magnetic
+ordering exists between $x = 0.0$ and 0.25 (MnPSe$_3$-type) and between $x =
+0.875$ and $1$ (FePSe$_3$-type). A short-range magnetic order with existence of
+both MnPSe$_3$- and FePSe$_3$-type nano-clusters has been established between
+$x = 0.25$ and $0.875$. Irreversibility in dc magnetization measurements, also
+characterized by isothermal and thermoremanent magnetization measurements
+suggest similarities to magnetic nanoparticles where uncompensated surface
+spins result in a non-zero TRM and IRM response, further reinforcing existence
+of magnetic nano-clusters or domains. A spin glass state, observed in analogous
+Mn$_{1-x}$Fe$_x$PS$_3$, has been ruled out and formation of nano-clusters
+exhibiting both ordering types results from unusually high anisotropy values.
+The effect of ligand contributions to the spin-orbit interactions has been
+suggested as a possible explanation for high $D$ values in these compounds.",1902.09655v2
+2019-02-27,Phenomenology of $^{63}$Cu nuclear relaxation in cuprate superconductors,"Nuclear relaxation is an important thermodynamic probe of electronic
+excitations, in particular in conducting and superconducting systems. Here, an
+empirical phenomenology based on all available literature data for planar Cu in
+hole-doped cuprates is developed. It is found that most of the seemingly
+different relaxation rates among the systems are due to a temperature
+independent anisotropy that affects the mostly measured $1/T_{1\parallel}$, the
+rate with an external magnetic field along the crystal $c$-axis, while
+$1/T_{1\perp}$ is largely independent on doping and material above the critical
+temperature of superconductivity ($T_c$). This includes very strongly overdoped
+systems that show Fermi liquid behavior and obey the Korringa law. Below $T_c$
+the relaxation rates are similar, as well, if plotted against the reduced
+temperature $T/T_c$. Thus, planar Cu nuclear relaxation is governed by a
+simple, dominant mechanism that couples the nuclei with varying anisotropy to a
+rather ubiquitous bath of electronic excitations that appear Fermi liquid-like
+irrespective of doping and family. In particular, there is no significant
+enhancement of the relaxation due to electronic spin fluctuations, different
+from earlier conclusions. Only the La$_{2-x}$Sr$_x$CuO$_4$ family appears to be
+an outlier as additional relaxation is present, however, the anisotropy remains
+temperature independent. Also systems with very low doping levels, for which
+there is a lack of data, may behave differently.",1902.10625v2
+2019-03-19,Axon diameters and myelin content modulate microscopic fractional anisotropy at short diffusion times in fixed rat spinal cord,"Mapping tissue microstructure accurately and noninvasively is one of the
+frontiers of biomedical imaging. Diffusion Magnetic Resonance Imaging (MRI) is
+at the forefront of such efforts, as it is capable of reporting on microscopic
+structures orders of magnitude smaller than the voxel size by probing
+restricted diffusion. Double Diffusion Encoding (DDE) and Double Oscillating
+Diffusion Encoding (DODE) in particular, are highly promising for their ability
+to report on microscopic fractional anisotropy ({\mu}FA), a measure of the pore
+anisotropy in its own eigenframe, irrespective of orientation distribution.
+However, the underlying correlates of {\mu}FA have insofar not been studied.
+Here, we extract {\mu}FA from DDE and DODE measurements at ultrahigh magnetic
+field of 16.4T in the aim to probe fixed rat spinal cord microstructure. We
+further endeavor to correlate {\mu}FA with Myelin Water Fraction (MWF) derived
+from multiexponential T2 relaxometry, as well as with literature-based
+spatially varying axonal diameters. In addition, a simple new method is
+presented for extracting unbiased {\mu}FA from three measurements at different
+b-values. Our findings reveal strong anticorrelations between {\mu}FA (derived
+from DODE) and axon diameter in the distinct spinal cord tracts; a moderate
+correlation was also observed between {\mu}FA derived from DODE and MWF. These
+findings suggest that axonal membranes strongly modulate {\mu}FA, which - owing
+to its robustness towards orientation dispersion effects - reflects axon
+diameter much better than its typical FA counterpart. The {\mu}FA exhibited
+modulations when measured via oscillating or blocked gradients, suggesting
+selective probing of different parallel path lengths and providing insight into
+how those modulate {\mu}FA metrics. Our findings thus shed light into the
+underlying microstructural correlates of {\mu}FA and are (...)",1903.10377v1
+2019-03-27,Field-free spin-orbit-torque switching of perpendicular magnetization aided by uniaxial shape anisotropy,"It has been demonstrated that the switching of perpendicular magnetization
+can be achieved with spin orbit torque (SOT) at an ultrafast speed and low
+energy consumption. However, to make the switching deterministic, an
+undesirable magnetic field or unconventional device geometry is required to
+break the structure inverse symmetry. Here we propose a novel scheme for
+SOT-induced field-free deterministic switching of perpendicular magnetization.
+The proposed scheme can be implemented in a simple magnetic tunnel junction
+(MTJ) /heavy-metal system, without the need of complicated device structure.
+The perpendicular-anisotropy MTJ is patterned into elliptical shape and
+misaligned with the axis of the heavy metal, so that the uniaxial shape
+anisotropy aids the magnetization switching. Furthermore, unlike the
+conventional switching scheme where the switched final magnetization state is
+dependent on the direction of the applied current, in our scheme the bipolar
+switching is implemented by choosing different current paths, which offers a
+new freedom for developing novel spintronics memories or logic devices. Through
+the macrospin simulation, we show that a wide operation window of the applied
+current pulse can be obtained in the proposed scheme. The precise control of
+pulse amplitude or pulse duration is not required. The influences of key
+parameters such as damping constant and field-like torque strength are
+discussed as well.",1903.11487v1
+2019-04-15,Anisotropic upper critical field of pristine and proton-irradiated single crystals of the magnetically ordered superconductor RbEuFe$_4$As$_4$,"We present a study of the upper critical field, H$_{c2}$, of pristine and
+proton-irradiated RbEuFe$_4$As$_4$ crystals in pulsed magnetic fields of up to
+65 T. The data for H$_{c2}$ reveal pronounced downwards curvature, particularly
+for the in-plane field orientation, and a superconducting anisotropy that
+decreases with decreasing temperature. These features are indicative of Pauli
+paramagnetic limiting. For the interpretation of these data, we use a model of
+a clean single-band superconductor with an open Fermi surface in the shape of a
+warped cylinder, which includes strong paramagnetic limiting. Fits to the data
+reveal that the in-plane upper critical field is Pauli paramagnetic limited,
+while the out-of-plane upper critical field is orbitally limited and that the
+orbital and paramagnetic fields have opposite anisotropies. A consequence of
+this particular combination is the unusual inversion of the anisotropy,
+$H_{c2}^{ab} < H_{c2}^c$, of the irradiated sample at temperatures below 10 K.
+The fits also yield an in-plane Maki parameter, $\alpha_M^{110} \approx$ 2.6,
+exceeding the critical value for the formation of the
+Fulde-Ferrell-Larkin-Ovchinnikov state. Nevertheless, the current measurements
+did not reveal direct evidence for the occurrence of this state.",1904.07203v2
+2019-04-19,Secondary CMB temperature anisotropies from magnetic reheating,"Spatially fluctuating primordial magnetic fields (PMFs) inhomogeneously
+reheat the Universe when they dissipate deep inside the horizon before
+recombination. Such an energy injection turns into an additional photon
+temperature perturbation. We investigate secondary cosmic microwave background
+(CMB) temperature anisotropies originated from this mechanism, which we call
+{\it inhomogeneous magnetic reheating}. We find that it can bring us
+information about non-linear coupling between PMFs and primordial curvature
+perturbations parametrized by $b_{\rm NL}$, which should be important for
+probing the generation mechanism of PMFs. In fact, by using current CMB
+observations, we obtain an upper bound on the non-linear parameter as $\log
+(b_{\rm NL} (B_{\lambda}/{\rm nG})^2) \lesssim {-36.5n_{B} - 94.0}$ with
+$B_{\lambda}$ and $n_{\rm B}$ being a magnetic field amplitude smoothed over
+$\lambda=1\; {\rm Mpc}$ scale and a spectral index of the PMF power spectrum,
+respectively. Our constraints are far stronger than a previous forecast based
+on the future CMB spectral distortion anisotropy measurements because
+inhomogeneous magnetic reheating covers a much wider range of scales, i.e.,
+$1\; {\rm Mpc}^{-1} \lesssim k\lesssim 10^{15}\; {\rm Mpc}^{-1}$.",1904.09121v2
+2019-04-30,Tunable ferromagnetic resonance in coupled trilayers with crossed in-plane and perpendicular magnetic anisotropies,"A novel approach to tune the ferromagnetic resonance frequency of a soft
+magnetic Ni$_{80}$Fe$_{20}$ (Permalloy = Py) film with in-plane magnetic
+anisotropy (IMA) based on the controlled coupling to a hard magnetic
+NdCo$_\text{x}$ film with perpendicular magnetic anisotropy (PMA) through a
+non-magnetic Al spacer is studied. Using transverse magneto-optical Kerr effect
+(TMOKE), alternating gradient magnetometry (AGM) as well as vector network
+analyzer ferromagnetic resonance (VNA-FMR) spectroscopy, the influence of both
+Co concentration and Al spacer thickness on the static and dynamic magnetic
+properties of the coupled IMA/PMA system is investigated. Compared to a single
+Py film, two striking effects of the coupling between IMA and PMA layers can be
+observed in their FMR spectra. First, there is a significant increase in the
+zero-field resonance frequency from 1.3 GHz up to 6.6 GHz, and second, an
+additional frequency hysteresis occurs at low magnetic fields applied along the
+hard axis. The maximum frequency difference between the frequency branches for
+increasing and decreasing magnetic field is as high as 1 GHz, corresponding to
+a tunability of about 20% at external fields of typically less than $\pm$70 mT.
+The origin of the observed features in the FMR spectra is discussed by means of
+magnetization reversal curves.",1904.13275v1
+2019-05-02,Impact of single atomic defects and vacancies on the magnetic anisotropy energy of CoPt thin films,"The impact of surface vacancies and single adatoms on the magnetic properties
+of tetragonal {\bf{L1}$_{0}$} CoPt thin films is investigated from first
+principles. We consider Co and Fe single adatoms deposited on a Pt-terminated
+thin film while a Pt adatom is assumed to be supported by a Co-terminated film.
+The vacancy is injected in the top-surface layer of the films with both types
+of termination. After finding the most stable location of the defects, we
+discuss their magnetic properties tight to those of the substrate and
+investigate the magnetic crystalline anisotropy energy (MAE). Previous
+simulations [Brahimi et al. J. Phys.: Condens. Matter. \textbf{28}, 496002
+(2016)] predicted a large out-of-plane surface MAE for the Pt-terminated CoPt
+films (4 meV per f.u.) in contrast to in-plane surface MAE for Co-terminated
+films (-1 meV per f.u.). Here, we find that the surface MAE is significantly
+modified upon the presence of the atomic defects. All investigated defects
+induce an in-plane MAE, which is large enough for Fe adatom and Pt vacancy to
+switch the surface MAE from out-of-plane to in-plane for the Pt-terminated
+films. Interestingly, among the investigated defects Pt vacancy has the largest
+effect on the MAE in contrast to Co vacancy, which induced the smallest but
+still significant effect. This behavior is explained in terms of the orbital
+moment anisotropy of the thin films.",1905.00674v1
+2019-05-03,Toggle Spin-Orbit Torque MRAM with Perpendicular Magnetic Anisotropy,"Spin-orbit torque (SOT) is a promising switching mechanism for magnetic
+random-access memory (MRAM) as a result of the potential for improved switching
+speed and energy-efficiency. It is of particular interest to develop an
+SOT-MRAM device with perpendicular magnetic anisotropy (PMA) in order to
+leverage the greater density and thermal stability achievable with PMA as
+opposed to in-plane magnetic anisotropy. However, the orthogonality between SOT
+and PMA prevents deterministic directional switching without an additional
+device component that breaks the symmetry, such as an external magnetic field
+or complex physical structure; not only do these components complicate
+fabrication, they also are not robust to variations in fabrication and applied
+switching current. This letter therefore proposes a simple SOT-MRAM structure
+with PMA in which deterministic toggle switching is achieved without requiring
+additional device components. Furthermore, this toggle PMA SOT-MRAM is shown to
+be far more robust than previous approaches for directional PMA SOT-MRAM, with
+greater than 50% tolerance to applied switching current magnitude. This letter
+describes the physical structure and toggle switching mechanism, provides
+micromagnetic simulations demonstrating its feasibility, and evaluates the
+robustness and tolerance to material parameters to guide the fabrication of
+optimized devices that will jumpstart the third generation of MRAM.",1905.01125v1
+2019-05-13,Parallel-propagating Fluctuations at Proton-kinetic Scales in the Solar Wind are Dominated by Kinetic Instabilities,"We use magnetic helicity to characterise solar wind fluctuations at
+proton-kinetic scales from Wind observations. For the first time, we separate
+the contributions to helicity from fluctuations propagating at angles
+quasi-parallel and oblique to the local mean magnetic field, $\mathbf{B}_0$. We
+find that the helicity of quasi-parallel fluctuations is consistent with
+Alfv\'en-ion cyclotron and fast magnetosonic-whistler modes driven by proton
+temperature anisotropy instabilities and the presence of a relative drift
+between $\alpha$-particles and protons. We also find that the helicity of
+oblique fluctuations has little dependence on proton temperature anisotropy and
+is consistent with fluctuations from the anisotropic turbulent cascade. Our
+results show that parallel-propagating fluctuations at proton-kinetic scales in
+the solar wind are dominated by proton temperature anisotropy instabilities and
+not the turbulent cascade. We also provide evidence that the behaviour of
+fluctuations at these scales is independent of the origin and macroscopic
+properties of the solar wind.",1905.04951v2
+2019-05-20,Micromagnetic Modelling of the Heat Assisted Switching Process in high Anisotropy FePt Granular Thin Films,"The dynamic process of assisted magnetic switchins has been simulated to
+investigate the associated physics. The model uses a Voronoi construction to
+determine the physical structure of the nano granular thin film recording
+media; and the Landau-Lifshitz-Bloch (LLB) equation is solved to evolve the
+magnetic system in time. The reduction of the magnetization is determined over
+a range of peak system temperatures and for a number of anisotropy values. The
+results show that the HAMR process is not simply magnetization reversal over a
+thermally reduced energy barrier. To achieve full magnetization reversal (for
+all anisotropies investigated) an applied field strength of at least 6kOe is
+required and the peak system temperature must reach at least the Curie point
+(Tc). When heated to Tc the magnetization associated with each grain is
+destroyed, which invokes the non-precessional linear reversal mode. Reversing
+the magnetization through this linear reversal mode is favourable, as the
+reversal time is two orders of magnitude smaller than that associated with
+precession. Under these conditions, as the temperature decreases to ambient,
+the magnetization recovers in the direction of the applied field, completing
+the reversal process. Also the model produces results which are consistent with
+the concept of thermal writability; when heating the media to Tc, the smaller
+grains require a larger field strength to reverse the magnetization.",1905.08134v1
+2019-05-21,Anisotropic spin fluctuations in detwinned FeSe,"Superconductivity in FeSe emerges from a nematic phase that breaks four-fold
+rotational symmetry in the iron plane. This phase may arise from orbital
+ordering, spin fluctuations, or hidden magnetic quadrupolar order. Here we use
+inelastic neutron scattering on a mosaic of single crystals of FeSe detwinned
+by mounting on a BaFe2As2 substrate to demonstrate that spin excitations are
+most intense at the antiferromagnetic wave vectors QAF = (1, 0) at low energies
+E = 6-11 meV in the normal state. This two-fold (C2) anisotropy is reduced at
+lower energies 3-5 meV, indicating a gapped four-fold (C4) mode. In the
+superconducting state, however, the strong nematic anisotropy is again
+reflected in the spin resonance (E = 3.7 meV) at QAF with incommensurate
+scattering around 5-6 meV. Our results highlight the extreme electronic
+anisotropy of the nematic phase of FeSe and are consistent with a highly
+anisotropic superconducting gap driven by spin fluctuations.",1905.08399v1
+2019-05-21,Orbital-flop Induced Magnetoresistance Anisotropy in Rare Earth Monopnictide CeSb,"The charge and spin of the electrons in solids have been extensively
+exploited in electronic devices and in the development of spintronics. Another
+attribute of electrons - their orbital nature - is attracting growing interest
+for understanding exotic phenomena and in creating the next-generation of
+quantum devices such as orbital qubits. Here, we report on orbital-flop induced
+magnetoresistance anisotropy in CeSb. In the low temperature high
+magnetic-field driven ferromagnetic state, a series of additional minima appear
+in the angle-dependent magnetoresistance. These minima arise from the
+anisotropic magnetization originating from orbital-flops and from the enhanced
+electron scattering from magnetic multidomains formed around the first-order
+orbital-flop transition. The measured magnetization anisotropy can be accounted
+for with a phenomenological model involving orbital-flops and a spin-valve-like
+structure is used to demonstrate the viable utilization of orbital-flop
+phenomenon. Our results showcase a contribution of orbital behavior in the
+emergence of intriguing phenomena.",1905.08682v1
+2019-05-22,Whistler wave generation by halo electrons in the solar wind,"We present an analysis of simultaneous particle and field measurements from
+the ARTEMIS spacecraft which demonstrate that quasi-parallel whistler waves in
+the solar wind can be generated locally by a bulk flow of halo electrons
+(whistler heat flux instability). ARTEMIS observes quasi-parallel whistler
+waves in the frequency range $\sim 0.05 - 0.2 f_{ce}$ simultaneously with
+electron velocity distribution functions that are a combination of
+counter-streaming core and halo populations. A linear stability analysis shows
+that the plasma is stable when there are no whistler waves, and unstable in the
+presence of whistler waves. In the latter case, the stability analysis shows
+that the whistler wave growth time is from a few to ten seconds at frequencies
+and wavenumbers that match the observations. The observations clearly
+demonstrate that the temperature anisotropy of halo electrons crucially affects
+the heat flux instability onset: a slight anisotropy
+$T_{\parallel}/T_{\perp}>1$ may quench the instability, while a slight
+anisotropy $T_{\parallel} / T_{\perp}<1$ may significantly increase the growth
+rate. These results demonstrate that heat flux inhibition is strongly dependent
+on the microscopic plasma properties.",1905.08954v1
+2019-05-28,Galactic Cosmic-Ray Anisotropies: Voyager 1 in the Local Interstellar Medium,"Since crossing the heliopause on August 25, 2012, Voyager 1 observed
+reductions in galactic cosmic ray count rates caused by a time-varying
+depletion of particles with pitch angles near 90-deg, while intensities of
+particles with other pitch angles remain unchanged. Between late 2012 and
+mid-2017, three large-scale events occurred, lasting from ~100 to ~630 days.
+Omnidirectional and directional high-energy data from Voyager 1's Cosmic Ray
+Subsystem are used to report cosmic ray intensity variations. Omnidirectional
+(greater than ~20 MeV) proton-dominated measurements show up to a 3.8%
+intensity reduction. Bi-directional (greater than ~70 MeV) proton-dominated
+measurements taken from various spacecraft orientations provide insight about
+the depletion region's spatial properties. We characterize the anisotropy as a
+""notch"" in an otherwise uniform pitch-angle distribution of varying depth and
+width centered about 90 degrees in pitch angle space. The notch averages 22-deg
+wide and 15% deep - signifying a depletion region that is broad and shallow.
+There are indications that the anisotropy is formed by a combination of
+magnetic trapping and cooling downstream of solar-induced transient
+disturbances in a region that is also likely influenced by the highly
+compressed fields near the heliopause.",1905.11990v1
+2019-06-07,Anisotropy-temperature phase diagram for the two-dimensional dipolar Heisenberg model with and without magnetic field,"We investigate phase transitions in the two-dimensional dipolar Heisenberg
+model with uniaxial anisotropy with a specific ratio between the exchange and
+dipolar constants, $\delta=1$. We obtain the $\eta$--$T$ (anisotropy vs.
+temperature) phase diagrams for typical values of magnetic field by a Monte
+Carlo method with an $O(N)$ algorithm. We find that at lower fields, the
+$\eta$--$T$ phase diagram consists of the planar ferromagnetic (F),
+(perpendicular) stripe-ordered (SO), and paramagnetic (P) phases, and is
+characterized by the triple point. In the SO phase realized at larger $\eta$
+and smaller $T$, the SO pattern changes depending on the field. On the other
+hand, we find that at higher fields, the SO phase does not exist, while the
+planer F phase robustly remains. We study the properties of the phase
+boundaries by employing finite-size-scaling analyses. We find that the slope of
+the spin-reorientation-transition line is positive with and without field,
+i.e., $\frac{d\eta}{dT}>0$, which implies that the planar F phase changes to
+the SO phase with lowering temperature. In the phase diagrams we observe a
+characteristic shape of the P--planer F phase-transition line, whose maximum
+point of $\eta$ is located at an intermediate temperature. This structure leads
+to the temperature-induced reentrant transition associated with P and planar F
+phases, which appears in successive phase transitions with lowering
+temperature: P $\rightarrow$ planar F $\rightarrow$ P $\rightarrow$ SO phase at
+lower fields and P $\rightarrow$ planar F $\rightarrow$ P phases at higher
+fields.",1906.02954v1
+2019-06-28,Mapping different skyrmion phases in double wedges of Ta/FeCoB(tFeCoB)/Ta(tTa)Ox,"Skyrmions are chiral magnetic textures that have immense potential for
+applications in spintronic devices. However, their formation is quite
+challenging and necessitates a subtle balance of the magnetic interactions at
+play. Here, we study Ta/FeCoB/TaOx trilayer using crossed double wedges i.e.
+thickness gradients of FeCoB and of top Ta, which is subsequently oxidized
+leading to an oxidation gradient. This enabled us to observe micron-sized
+skyrmions in the vicinity of different transition regions of the sample: from
+perpendicular magnetic anisotropy to paramagnetic phase and also from
+perpendicular to in-plane magnetic anisotropy. These observations can be
+explained by the isolated bubble model taking into account the different energy
+contributions at play namely anisotropy, exchange, Dzyaloshinskii-Moriya,
+dipolar and Zeeman. We also qualitatively compare the current-induced motion of
+skyrmions obtained in different transition regions. Our study not only provides
+an effective means to form skyrmions by tuning the interfacial magnetic
+properties but also highlights the differences pertaining to the skyrmions
+observed in different transition zones, which is extremely crucial for any
+envisaged application.",1906.12271v2
+2019-07-02,"In-plane to perpendicular magnetic anisotropy switching in heavily-Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb with high Curie temperature","We report switching of magnetic anisotropy (MA) from in-plane to
+perpendicular with increasing the thickness d of a (001)-oriented
+ferromagnetic-semiconductor (FMS) (Ga0.7,Fe0.3)Sb layer with a high Curie
+temperature (Tc > 320 K), using ferromagnetic resonance at room temperature. We
+show that the total MA energy (E) along the [001] direction changes its sign
+from positive (in-plane) to negative (perpendicular) with increasing d above an
+effective critical value \mathrm{d}_\mathrm{C}^\mathrm{*}\ ~ 42 nm. We reveal
+that (Ga,Fe)Sb has two-fold symmetry in the film plane. Meanwhile, in the plane
+perpendicular to the film including the in-plane [110] axis, the two-fold
+symmetry with the easy magnetization axis along [110] changes to four-fold
+symmetry with easy magnetization axis along <001> with increasing d. This
+peculiar behavior is different from that of (Ga,Mn)As, in which only the
+in-plane MA depends on the film thickness and has four-fold symmetry due to its
+dominant cubic anisotropy along the <100> axes. This work provides an important
+guide for controlling the easy magnetization axis of high-Tc FMS (Ga,Fe)Sb for
+room-temperature device applications.",1907.01188v1
+2019-08-02,Magnetic and superconducting anisotropy in Ni-doped RbEuFe$_4$As$_4$ single crystals,"We investigate the effect of Ni doping on the Fe-site in single crystals of
+the magnetic superconductor RbEuFe$_4$As$_4$ for doping concentrations of up to
+4%. A clear suppression in the superconducting transition temperature is
+observed in specific heat, resistivity and magnetization measurements. Upon
+Ni-doping, the resistivity curves shift up in a parallel fashion indicating a
+strong increase of the residual resistivity due to scattering by charged dopand
+atoms while the shape of the curve and thus the electronic structure appears
+largely unchanged. The observed step $\Delta C/T_c$ at the superconducting
+transition decreases strongly for increasing Ni doping in agreement with
+expectations based on a model of multi-band superconductivity and strong
+inter-band pairing. The upper critical field slopes are reduced upon Ni doping
+for in- as well as out-of-plane fields leading to a small reduction in the
+superconducting anisotropy. The specific heat measurements of the magnetic
+transition reveal the same BKT behavior close to the transition temperature
+$T_m$ for all doping levels. The transition temperature is essentially
+unchanged upon doping. The in to out-of-plane anisotropy of Eu-magnetism
+observed at small magnetic fields is unaltered as compared to the undoped
+compound. All of these observations indicate a decoupling of the Eu magnetism
+from superconductivity and essentially no influence of Ni doping on the Eu
+magnetism in this compound.",1908.00773v1
+2019-08-07,A nano-carbon route to rare earth free permanent magnetism,"High coercivity magnets are an important resource for renewable energy,
+electric vehicles and memory technologies. Most hard magnetic materials
+incorporate rare-earths such as neodymium and samarium, but the concerns about
+the environmental impact and supply stability of these materials is prompting
+research into alternatives. Here, we present a hybrid bilayer of cobalt and the
+nano-carbon molecule C60 which exhibits significantly enhanced coercivity with
+minimal reduction in magnetisation. We demonstrate how this anisotropy
+enhancing effect cannot be described by existing models of molecule-metal
+magnetic interfaces. We outline a new form of magnetic anisotropy, arising from
+asymmetric magneto-electric coupling in the metal-molecule interface. Because
+this phenomenon arises from pi-d hybrid orbitals, we propose calling this
+effect pi-anisotropy. While the critical temperature of this effect is
+currently limited by the rotational degree of freedom of the chosen molecule,
+C60, we describe how surface functionalisation would allow for the design of
+room-temperature, carbon based hard magnetic films.",1908.02544v3
+2019-08-15,CMB sky for an off-center observer in a local void I: framework for forecasts,"The Universe is not perfectly homogeneous, the large scale structure forms
+overdense regions and voids. In this paper, we consider the possibility that we
+occupy a special position in our Universe, close to the center of a local
+underdense region that we model as an LTB void embedded in a homogeneous and
+isotropic Universe. The CMB sky measured by an off-center observer in this void
+is not statistically isotropic. In addition to the non-stochastic CMB
+anisotropies due to the geometry of the model, we also observe a lensing-like
+distortion of the CMB anisotropies. In this article, we propose a framework to
+forecast the precision with which we can measure the amplitude of the
+lensing-like deformation of the CMB temperature anisotropies. For illustrative
+purposes, we apply this method to a couple of large-scale void models differing
+over the matter density profile and we show that the CMB temperature data from
+the Planck satellite is potentially capable to detect the effect for the large
+voids chosen here. A companion paper will be dedicated to a systematic
+exploration of different realistic void models.",1908.05484v2
+2019-08-22,Influence of structure and cation distribution on magnetic anisotropy and damping in Zn/Al doped nickel ferrites,"An in-depth analysis of Zn/Al doped nickel ferrites grown by reactive
+magnetron sputtering is relevant due to their promising characteristics for
+applications in spintronics. The material is insulating and ferromagnetic at
+room temperature with an additional low magnetic damping. By studying the
+complex interplay between strain and cation distribution their impact on the
+magnetic properties, i.e. anisotropy, damping and g-factor is unravelled. In
+particular, a strong influence of the lattice site occupation of
+Ni$^{2+}_{\text{Td}}$ and cation coordination of Fe$^{2+}_{\text{Oh}}$ on the
+intrinsic damping is found. Furthermore, the critical role of the incorporation
+of Zn$^{2+}$ and Al$^{3+}$ is evidenced by comparison with a sample of altered
+composition. Especially, the dopant Zn$^{2+}$ is evidenced as a tuning factor
+for Ni$^{2+}_{\text{Td}}$ and therefore unquenched orbital moments directly
+controlling the g-factor. A strain-independent reduction of the magnetic
+anisotropy and damping by adapting the cation distribution is demonstrated.",1908.08257v3
+2019-08-28,A Method for Dimensionally Adaptive Sparse Trigonometric Interpolation of Periodic Functions,"We present a method for dimensionally adaptive sparse trigonometric
+interpolation of multidimensional periodic functions belonging to a smoothness
+class of finite order. This method targets applications where periodicity must
+be preserved and the precise anisotropy is not known a priori. To the authors'
+knowledge, this is the first instance of a dimensionally adaptive sparse
+interpolation algorithm that uses a trigonometric interpolation basis. The
+motivating application behind this work is the adaptive approximation of a
+multi-input model for a molecular potential energy surface (PES) where each
+input represents an angle of rotation. Our method is based on an anisotropic
+quasi-optimal estimate for the decay rate of the Fourier coefficients of the
+model; a least-squares fit to the coefficients of the interpolant is used to
+estimate the anisotropy. Thus, our adaptive approximation strategy begins with
+a coarse isotropic interpolant, which is gradually refined using the estimated
+anisotropic rates. The procedure takes several iterations where ever-more
+accurate interpolants are used to generate ever-improving anisotropy rates. We
+present several numerical examples of our algorithm where the adaptive
+procedure successfully recovers the theoretical ""best"" convergence rate,
+including an application to a periodic PES approximation. An open-source
+implementation of our algorithm resides in the Tasmanian UQ library developed
+at Oak Ridge National Laboratory.",1908.10672v2
+2019-09-17,Aniotropy of in-plane g-factor of electrons in HgTe quantum wells,"The results of experimental studies of the Shubnikov-de Haas (SdH) efect in
+the (013)-HgTe/Hg$_{1-x}$Cd$_x$Te quantum wells (QWs) of electron type of
+conductivity both with normal and inverted energy spectrum are reported.
+Comprehensive analysis of the SdH oscillations measured for the different
+orientations of magnetic field relative to the quantum well plane and
+crystallographic exes allows us to investigate the anisotropy of the Zeeman
+effect. For the QWs with inverted spectrum, it has been shown that the ratio of
+the spin splitting to the orbital one is strongly dependent not only on the
+orientation of the magnetic field relative to the QW plane but also on the
+orientation of the in-plane magnetic field component relative to
+crystallographic axes laying in the QW plane that implies the strong anisotropy
+of in-plane g-factor. In the QW with normal spectrum, this ratio strongly
+depends on the angle between the magnetic field and the normal to the QW plane
+and reveals a very slight anisotropy in the QW plane. To interpret the data,
+the Landau levels in the tilted magnetic field are calculated within the
+framework of four-band \emph{kP} model. It is shown that the experimental
+results can be quantitatively described only with taking into account the
+interface inversion asymmetry.",1909.07611v1
+2019-09-17,Single spin resonance driven by electric modulation of the g factor anisotropy,"We address the problem of electronic and nuclear spin resonance of an
+individual atom on a surface driven by a scanning tunnelling microscope.
+Several mechanisms have been proposed so far, some of them based on the
+modulation of exchange and crystal field associated to a piezoelectric
+displacement of the adatom driven by the RF tip electric field. Here we
+consider a new mechanism, where the piezoelectric displacement modulates the g
+factor anisotropy, leading both to electronic and nuclear spin flip
+transitions. We discuss thoroughly the cases of Ti-H (S = 1/2) and Fe (S = 2)
+on MgO, relevant for recent experiments. We model the system using two
+approaches. First, an analytical model that includes crystal field, spin orbit
+coupling and hyperfine interactions. Second, we carry out density functional
+based calculations. We find that the modulation of the anisotropy of the g
+tensor due to the piezoelectric displacement of the atom is an additional
+mechanism for STM based single spin resonance, that would be effective in S =
+1/2 adatoms with large spin orbit coupling. In the case of Ti-H on MgO, we
+predict a modulation spin resonance frequency driven by the DC electric field
+of the tip.",1909.07942v1
+2019-09-19,Energy-based analysis and anisotropic spectral distribution of internal gravity waves in strongly stratified turbulence,"Stratified turbulence shows scale- and direction-dependent anisotropy and the
+coexistence of weak turbulence of internal gravity waves and strong turbulence
+of eddies. Straightforward application of standard analyses developed in
+isotropic turbulence sometimes masks important aspects of the anisotropic
+turbulence. To capture detailed structures of the energy distribution in the
+wave-number space, it is indispensable to examine the energy distribution with
+non-integrated spectra by fixing the codimensional wave-number component or in
+the two-dimensional domain spanned by both the horizontal and vertical wave
+numbers. Indices which separate the range of the anisotropic weak-wave
+turbulence in the wave-number space are proposed based on the decomposed
+energies. In addition, the dominance of the waves in the range is also verified
+by the small frequency deviation from the linear dispersion relation. In the
+wave-dominant range, the linear wave periods given by the linear dispersion
+relation are smaller than approximately one third of the eddy-turnover time.
+The linear wave periods reflect the anisotropy of the system, while the
+isotropic Brunt-V\""ais\""al\""a period is used to evaluate the Ozmidov wave
+number, which is necessarily isotropic. It is found that the time scales in
+consideration of the anisotropy of the flow field must be appropriately
+selected to obtain the critical wave number separating the weak-wave
+turbulence.",1909.08779v1
+2019-09-27,Magnetic Guinier law,"Small-angle scattering of x-rays and neutrons is a routine method for the
+determination of nanoparticle sizes. The so-called Guinier law represents the
+low-q approximation for the small-angle scattering curve from an assembly of
+particles. The Guinier law has originally been derived for nonmagnetic
+particle-matrix-type systems, and it is successfully employed for the
+estimation of particle sizes in various scientific domains (e.g., soft matter
+physics, biology, colloidal chemistry, materials science). An important
+prerequisite for it to apply is the presence of a discontinuous interface
+separating particles and matrix. Here, we introduce the Guinier law for the
+case of magnetic small-angle neutron scattering (SANS) and experimentally
+demonstrate its applicability for the example of nanocrystalline cobalt. It is
+well-known that the magnetic microstructure of nanocrystalline ferromagnets is
+highly nonuniform on the nanometer length scale and characterized by a spectrum
+of continuously varying long-wavelength magnetization fluctuations, i.e., these
+systems do not manifest sharp interfaces in their magnetization profile. The
+magnetic Guinier radius depends on the applied magnetic field, on the magnetic
+interactions (exchange, magnetostatics), and on the magnetic anisotropy-field
+radius, which characterizes the size over which the magnetic anisotropy field
+is coherently aligned into the same direction. In contrast to the nonmagnetic
+conventional Guinier law, the magnetic version can be applied to fully dense
+random-anisotropy-type ferromagnets.",1909.12687v2
+2019-10-02,Whistler instability stimulated by the suprathermal electrons present in space plasmas,"In the absence of efficient collisions, deviations from thermal equilibrium
+of plasma particle distributions are controlled by the self-generated
+instabilities. The whistler instability is a notorious example, usually
+responsible for the regulation of electron temperature anisotropy $A =
+T_{\perp}/T_\parallel>$ (with $\perp, \parallel$ respective to the magnetic
+field direction) observed in space plasmas, e.g., solar wind and planetary
+magnetospheres. Suprathermal electrons present in these environments change the
+plasma dispersion and stability properties, with expected consequences on the
+kinetic instabilities and the resulting fluctuations, which, in turn, scatter
+the electrons and reduce their anisotropy. In order to capture these mutual
+effects we use a quasilinear kinetic approach and PIC simulations, which
+provide a comprehensive characterization of the whistler instability under the
+influence of suprathermal electrons. Analysis is performed for a large variety
+of plasma conditions, ranging from low-beta plasmas encountered in outer corona
+or planetary magnetospheres to a high-beta solar wind characteristic to large
+heliospheric distances. Enhanced by the suprathermal electrons, whistler
+fluctuations stimulate the relaxation of temperature anisotropy, and this
+influence of suprathermals increases with plasma beta parameter.",1910.01506v1
+2019-10-04,Spin fluctuation anisotropy as a probe of orbital-selective hole-electron quasiparticle excitations in detwinned Ba(Fe1-xCox)2As2,"We use inelastic neutron scattering to study spin excitation anisotropy in
+mechanically detwinned Ba(Fe1-xCox)2As2 with x = 0.048 and 0.054. Both samples
+exhibit a tetragonal-to-orthorhombic structural transition at Ts, a collinear
+static antiferromagnetic (AF) order at wave vector Q1 = QAF = (1, 0) below the
+Neel temperature TN, and superconductivity below Tc (Ts > TN > Tc). In the high
+temperature paramagnetic tetragonal phase (T > Ts), spin excitations centered
+at Q1 and Q2 = (0, 1) are gapless and have four-fold (C4) rotational symmetry.
+On cooling to below TN but above Tc, spin excitations become highly
+anisotropic, developing a gap at Q2 but still are gapless at Q1. Upon entering
+into the superconducting state, a neutron spin resonance appears at Q1 with no
+magnetic scattering at Q2. By comparing these results with those from angle
+resolved photoemission spectroscopy experiments, we conclude that the
+anisotropic shift of the dyz and dxz bands in detwinned Ba(Fe1-xCox)2As2 below
+Ts is associated with the spin excitation anisotropy, and the
+superconductivity-induced resonance arises from the electron-hole Fermi surface
+nesting of quasiparticles with the dyz orbital characters.",1910.01871v1
+2019-10-06,Ground-State Phase Diagram of an Anisotropic S=1 Ferromagnetic-Antiferromagnetic Bond-Alternating Chain,"By using mainly numerical methods, we investigate the ground-state phase
+diagram (GSPD) of an $S=1$ ferromagnetic-antiferromagnetic bond-alternating
+chain with the $XXZ$ and the on-site anisotropies. This system can be mapped
+onto an anisotropic spin-2 chain when the ferromagnetic interaction is much
+stronger than the antiferromagnetic interaction. Since there are many quantum
+parameters in this system, we numerically obtained the GSPD on the plane of the
+magnitude of the antiferromagnetic coupling versus its $XXZ$ anisotropy, by use
+of the exact diagonalization, the level spectroscopy as well as the
+phenomenological renormalization group. The obtained GSPD consists of six
+phases. They are the $XY$1, the large-$D$ (LD), the intermediate-$D$ (ID), the
+Haldane (H), the spin-1 singlet dimer (SD), and the N\'eel phases. Among them,
+the LD, the H, and the SD phases are the trivial phases, while the ID phase is
+the symmetry-protected topological phase. The former three are smoothly
+connected without any quantum phase transitions. It is also emphasized that the
+ID phase appears in a wider region compared with the case of the GSPD of the
+anisotropic spin-2 chain with the $XXZ$ and the on-site anisotropies. We also
+compare the obtained GSPD with the result of the perturbation theory.",1910.02456v1
+2019-10-11,Magnetization governed magnetoresistance anisotropy in topological semimetal CeBi,"Magnetic topological semimetals, the latest member of topological quantum
+materials, are attracting extensive attention as they may lead to
+topologically-driven spintronics. Currently, magnetotransport investigations on
+these materials are focused on anomalous Hall effect. Here, we report on the
+magnetoresistance anisotropy of topological semimetal CeBi, which has tunable
+magnetic structures arising from localized Ce 4f electrons and exhibits both
+negative and positive magnetoresistances, depending on the temperature. We
+found that the angle dependence of the negative magnetoresistance, regardless
+of its large variation with the magnitude of the magnetic field and with
+temperature, is solely dictated by the field-induced magnetization that is
+orientated along a primary crystalline axis and flops under the influence of a
+rotating magnetic field. The results reveal the strong interaction between
+conduction electrons and magnetization in CeBi. They also indicate that
+magnetoresistance anisotropy can be used to uncover the magnetic behavior and
+the correlation between transport phenomena and magnetism in magnetic
+topological semimetals.",1910.05247v1
+2019-10-19,Anomalies in the switching dynamics of C-type antiferromagnets and antiferromagnetic nanowires,"Antiferromagnets (AFMs) are widely believed to be superior than ferromagnets
+in spintronics because of their high stability due to the vanishingly small
+stray field. It is thus expected that the order parameter of AFM should always
+align along the easy-axis of the crystalline anisotropy. In contrast to this
+conventional wisdom, we find that the AFM order parameter switches away from
+the easy-axis below a critical anisotropy strength when an AFM is properly
+tailored into a nano-structure. The switching time first decreases and then
+increases with the damping. Above the critical anisotropy, the AFM order
+parameter is stable and precesses under a microwave excitation. However, the
+absorption peak is not at resonance frequency even for magnetic damping as low
+as 0.01. To resolve these anomalies, we first ascertain the hidden role of
+dipolar interaction that reconstructs the energy landscape of the nano-system
+and propose a model of damped non-linear pendulum to explain the switching
+behavior. In this framework, the second anomaly appears when an AFM is close to
+the boundary between underdamped and overdamped phases, where the observed
+absorption lineshape has small quality factor and thus is not reliable any
+longer. Our results should be significant to extract the magnetic parameters
+through resonance techniques.",1910.08668v1
+2019-10-31,Magnetoplasmons in monolayer black phosphorus structures,"Two-dimensional materials supporting deep-subwavelength plasmonic modes can
+also exhibit strong magneto-optical responses. Here, we theoretically
+investigate magnetoplasmons (MPs) in monolayer black phosphorus (BP) structures
+under moderate static magnetic fields. We consider three different structures,
+namely, a continuous BP monolayer, an edge formed by a semi-infinite sheet, and
+finally, a triangular wedge configuration. Each of these structures shows
+strongly anisotropic magneto-optical responses induced both by the external
+magnetic field and by the intrinsic anisotropy of the BP lattice. Starting from
+the magneto-optical conductivity of a single-layer of BP, we derive the
+dispersion relation of the MPs in the considered geometries, using a
+combination of analytical, semi-analytical, and numerical methods. We fully
+characterize the MP dispersions and the properties of the corresponding field
+distributions, and we show that these structures sustain strongly anisotropic
+subwavelength modes that are highly tunable. Our results demonstrate that MPs
+in monolayer BP, with its inherent lattice anisotropy as well as magnetically
+induced anisotropy, hold potential for tunable anisotropic materials operating
+below the diffraction limit, thereby paving the way for tailored nanophotonic
+devices at the nanoscale.",1910.14577v1
+2019-11-11,Determining the phase diagram of atomically thin layered antiferromagnet CrCl$_3$,"Changes in the spin configuration of atomically-thin, magnetic van-der-Waals
+multilayers can cause drastic modifications in their opto-electronic
+properties. Conversely, the opto-electronic response of these systems provides
+information about the magnetic state, very difficult to obtain otherwise. Here
+we show that in CrCl$_3$ multilayers, the dependence of the tunnelling
+conductance on applied magnetic field ($H$), temperature ($T$), and number of
+layers ($N$) tracks the evolution of the magnetic state, enabling the magnetic
+phase diagram of these systems to be determined experimentally. Besides a
+high-field spin-flip transition occurring for all thicknesses, the in-plane
+magnetoconductance exhibits an even-odd effect due to a low-field spin-flop
+transition. If the layer number $N$ is even, the transition occurs at $\mu_0 H
+\sim 0$ T due to the very small in-plane magnetic anisotropy, whereas for odd
+$N$ the net magnetization of the uncompensated layer causes the transition to
+occur at finite $H$. Through a quantitative analysis of the phenomena, we
+determine the interlayer exchange coupling as well as the staggered
+magnetization, and show that in CrCl$_3$ shape anisotropy dominates. Our
+results reveal the rich behaviour of atomically-thin layered antiferromagnets
+with weak magnetic anisotropy.",1911.04376v1
+2019-11-12,Morphology of CMB fields -- effect of weak gravitational lensing,"We study the morphology of the cosmic microwave background temperature and
+polarization fields using the shape and alignment parameters, $\beta$ and
+$\alpha$, that are constructed from the contour Minkowski tensor. The primary
+goal of our paper is to understand the effect of weak gravitational lensing on
+the morphology of the CMB fields. In order to isolate different physical
+effects that can be potentially confused with the effect of lensing, we first
+study the effect of varying the cosmology on $\alpha$ and $\beta$, and show
+that they are relatively insensitive to variation of cosmological parameters.
+Next we analyze the signatures of hemispherical anisotropy, and show that
+information of such anisotropy in $\alpha$ gets washed out at small angular
+scales and become pronounced only at large angular scales. For $\beta$ we find
+characteristic distortions which vary with the field threshold. We then study
+the effect of weak gravitational lensing using simulations of lensed
+temperature and $E$ and $B$ modes. We quantify the distortion induced in the
+fields across different angular scales. We find that lensing makes structures
+of all fields increasingly more anisotropic as we probe down to smaller scales.
+We find distinct behaviour of morphological distortions as a function of
+threshold for the different fields. The effect is small for temperature and $E$
+mode, while it is significantly large for $B$ mode. Further, we find that
+lensing does not induce statistical anisotropy, as expected from the isotropic
+distribution of large scale structure of matter. We expect that the results
+obtained in this work will provide insights on the reconstruction of the
+lensing potential.",1911.04740v1
+2019-11-18,Revisiting the role of intermittent heat transport towards Reynolds stress anisotropy in convective turbulence,"Thermal plumes are the energy containing eddy motions that carry heat and
+momentum in a convective boundary layer. The detailed understanding of their
+structure is of fundamental interest for a range of applications, from
+wall-bounded engineering flows to quantifying surface-atmosphere flux
+exchanges. We address the aspect of Reynolds stress anisotropy associated with
+the intermittent nature of heat transport in thermal plumes by performing an
+invariant analysis of the Reynolds stress tensor in an unstable atmospheric
+surface layer flow, using a field-experimental dataset. Given the intermittent
+and asymmetric nature of the turbulent heat flux, we formulate this problem in
+an event-based framework. In this approach, we provide structural descriptions
+of warm-updraft and cold-downdraft events and investigate the degree of
+isotropy of the Reynolds stress tensor within these events of different sizes.
+We discover that only a subset of these events are associated with the least
+anisotropic turbulence in highly-convective conditions. Additionally,
+intermittent large heat flux events are found to contribute substantially to
+turbulence anisotropy under unstable stratification. Moreover, we find that the
+sizes related to the maximum value of the degree of isotropy do not correspond
+to the peak positions of the heat flux distributions. This is because, the
+vertical velocity fluctuations pertaining to the sizes associated with the
+maximum heat flux, transport significant amount of streamwise momentum. A
+preliminary investigation shows that the sizes of the least anisotropic events
+probably scale with a mixed-length scale ($z^{0.5}\lambda^{0.5}$, where $z$ is
+the measurement height and $\lambda$ is the large-eddy length scale).",1911.07822v3
+2019-11-28,Continuous Histograms for Anisotropy of 2D Symmetric Piece-wise Linear Tensor Fields,"The analysis of contours of scalar fields plays an important role in
+visualization. For example the contour tree and contour statistics can be used
+as a means for interaction and filtering or as signatures. In the context of
+tensor field analysis, such methods are also interesting for the analysis of
+derived scalar invariants. While there are standard algorithms to compute and
+analyze contours, they are not directly applicable to tensor invariants when
+using component-wise tensor interpolation. In this chapter we present an
+accurate derivation of the contour spectrum for invariants with quadratic
+behavior computed from two-dimensional piece-wise linear tensor fields. For
+this work, we are mostly motivated by a consistent treatment of the anisotropy
+field, which plays an important role as stability measure for tensor field
+topology. We show that it is possible to derive an analytical expression for
+the distribution of the invariant values in this setting, which is exemplary
+given for the anisotropy in all details. Our derivation is based on a
+topological sub-division of the mesh in triangles that exhibit a monotonic
+behavior. This triangulation can also directly be used to compute the accurate
+contour tree with standard algorithms. We compare the results to a na\""ive
+approach based on linear interpolation on the original mesh or the subdivision.",1912.00739v1
+2019-12-09,An anisotropic interaction model with collision avoidance,"In this article an anisotropic interaction model avoiding collisions is
+proposed. Starting point is a general isotropic interacting particle system, as
+used for swarming or follower-leader dynamics. An anisotropy is induced by
+rotation of the force vector resulting from the interaction of two agents. In
+this way the anisotropy is leading to a smooth evasion behaviour. In fact, the
+proposed model generalizes the standard models, and compensates their drawback
+of not being able to avoid collisions. Moreover, the model allows for formal
+passage to the limit 'number of particles to infinity', leading to a mesoscopic
+description in the mean-field sense. Possible applications are autonomous
+traffic, swarming or pedestrian motion. Here, we focus on the latter, as the
+model is validated numerically using two scenarios in pedestrian dynamics. The
+first one investigates the pattern formation in a channel, where two groups of
+pedestrians are walking in opposite directions. The second experiment considers
+a crossing with one group walking from left to right and the other one from
+bottom to top. The well-known pattern of lanes in the channel and travelling
+waves at the crossing can be reproduced with the help of this anisotropic model
+at both, the microscopic and the mesoscopic level. In addition, the
+'right-before-left' and 'left-before-right' rule appear intrinsically for
+different anisotropy parameters.",1912.04234v2
+2019-12-24,Dark matter with excitable levels,"This paper explores the possibility that dark matter particles are objects
+with a set of excitable levels, as for a string or drum. A change in excitation
+is associated with the absorption or emission of a photon, and the probability
+of such a change is dependent on the ambient photon energy density. Particle
+mass comes entirely from excitations. Such dark matter with excitable levels,
+or DMWEL, particles have a distribution of masses which freezes out to its
+present-day form during the early universe. In the particular model considered,
+consistency with Planck CMB anisotropy observations implies a cautious lower
+bound on the energy of the first excitable level of 2 to 200 eV for a set of
+reference parameters. While laboratory detection looks to require a
+considerable increase in the power of controlled light-sources, it might be
+possible in the near future to detect or constrain DMWEL further through
+improved anisotropy observations, closer determination of the CMB's maximum
+deviation from a blackbody shape, or from gravitational probes of the dark
+matter power spectrum. For certain parameters near to the boundary of the
+region allowed by CMB anisotropies, DMWEL dark matter is cold, but with a
+cut-off halo mass many orders of magnitude greater than that typical for WIMP
+cold dark matter.",1912.11453v3
+2019-12-27,Anisotropy screening in Horndeski cosmologies,"We consider anisotropic cosmologies in a particular shift-symmetric Horndeski
+theory containing the $G^{\mu\nu}\partial_\mu\phi \partial_\nu\phi$ coupling,
+where $G^{\mu\nu}$ is the Einstein tensor. This theory admits stable in the
+future self-accelerating cosmologies whose tensor perturbations propagate with
+the velocity very close to the speed of light such that the theory agrees with
+the gravity wave observations. Surprisingly, we find that the anisotropies
+within the Bianchi I homogeneous spacetime model are screened at early time by
+the scalar charge, whereas at late times they are damped in the usual way.
+Therefore, contrary to what one would normally expect, the early state of the
+universe in the theory cannot be anisotropic and (locally) homogeneous in the
+absence of spatial curvature. The early universe cannot be isotropic either,
+because it should then be unstable with respect to inhomogeneous perturbations.
+As a result, the early universe should be inhomogeneous. At the same time, we
+find that in the spatially curved Bianchi IX case the anisotropies can be
+strong at early times even in the presence of a scalar charge.",1912.12320v2
+2019-12-30,Cross-Correlation of Far-Infrared Background Anisotropies and CMB Lensing from Herschel and Planck satellites,"The cosmic infrared background (CIB) anisotropies and cosmic microwave
+background (CMB) lensing are powerful measurements for exploring the
+cosmological and astrophysical problems. In this work, we measure the
+auto-correlation power spectrum of the CIB anisotropies in the Herschel-SPIRE
+HerMES Large Mode Survey (HeLMS) field, and the cross power spectrum with the
+CMB lensing measurements from the Planck satellite. The HeLMS field covers more
+than 270 deg^2, which is much larger than the previous analysis. We use the
+Herschel Level 1 time stream data to merge the CIB maps at 250, 350, and 500 um
+bands, and mask the areas where the flux is greater than 3-sigma (~50 mJy/beam)
+or no measured data. We obtain the final CIB power spectra at 100<ell<20000 by
+considering several effects, such as beam function, mode coupling, transfer
+function, and so on. We also calculate the theoretical CIB auto- and
+cross-power spectra of CIB and CMB lensing by assuming that the CIB emissivity
+follows Gaussian distribution in redshift. We find that, for the CIB auto power
+spectra, we obtain the signal to noise ratio (SNR) of 15.9, 15.7, and 15.3 at
+250, 350, and 500 um, and for the CIBxCMB lensing power spectra, SNR of 7.5,
+7.0, and 6.2 at 250, 350, and 500 um, respectively. Comparing to previous
+works, the constraints on the relevant CIB parameters are improved by factors
+of 2~5 in this study.",1912.12840v2
+2019-12-31,Noncoplanar ferrimagnetism and local crystalline-electric-field anisotropy in the quasicrystal approximant Au$_{70}$Si$_{17}$Tb$_{13}$,"Neutron scattering experiments have been performed to elucidate magnetic
+properties of the quasicrystal approximant Au$_{70}$Si$_{17}$Tb$_{13}$,
+consisting of icosahedral spin clusters in a body-centered-cubic lattice. Bulk
+magnetic measurements performed on the single crystalline sample unambiguously
+confirm long-range ordering at $T_{\rm C} = 11.6 \pm 1$ K. In contrast to the
+simple ferromagnetic response in the bulk measurements, single crystal neutron
+diffraction confirms a formation of intriguing non-collinear and non-coplanar
+magnetic order. The magnetic moment direction was found to be nearly tangential
+to the icosahedral cluster surface in the local mirror plane, which is quite
+similar to that recently found in the antiferromagnetic quasicrystal
+approximant Au$_{72}$Al$_{14}$Tb$_{14}$. Inelastic neutron scattering on the
+powdered sample exhibits a very broad peak centered at $\hbar \omega \simeq 4$
+meV. The observed inelastic spectrum was explained by the
+crystalline-electric-field model taking account of the chemical disorder at the
+fractional Au/Si sites. The resulting averaged anisotropy axis for the
+crystalline-electric-field ground state is consistent with the ordered moment
+direction determined in the magnetic structure analysis, confirming that the
+non-coplanar magnetic order is stabilized by the local uniaxial anisotropy.",1912.13180v1
+2020-01-09,Role of longitudinal fluctuations in L$1_0$ FePt,"L$1_0$ FePt is a technologically important material for a range of novel data
+storage applications. In the ordered FePt structure the normally non-magnetic
+Pt ion acquires a magnetic moment, which depends on the local field originating
+from the neighboring Fe atoms. In this work a model of FePt is constructed,
+where the induced Pt moment is simulated by using combined longitudinal and
+rotational spin dynamics. The model is parameterized to include a linear
+variation of the moment with the exchange field, so that at the Pt site the
+magnetic moment depends on the Fe ordering. The Curie temperature of FePt is
+calculated and agrees well with similar models that incorporate the Pt dynamics
+through an effective Fe-only Hamiltonian. By computing the dynamic correlation
+function the anisotropy field and the Gilbert damping are extracted over a
+range of temperatures. The anisotropy exhibits a power-law dependence with
+temperature with exponent $n\approx2.1$. This agrees well with what observed
+experimentally and it is obtained without including a two-ion anisotropy term
+as in other approaches. Our work shows that incorporating longitudinal
+fluctuations into spin dynamics calculations is crucial for understanding the
+properties of materials with induced moments.",2001.03074v1
+2020-01-13,Virial models and Anisotropy of Velocity Dispersion in e-galaxies,"A tensor virial approach is used to construct detailed models of 22 flattened
+ellipticals. The models are combined with the new observational data: extended
+surface brightness distributions, the profiles of isophotes flattening and
+their twisting, the rotation curves and the velocity dispersion profiles. A key
+feature of these models is a rigorous consideration of the influence of the
+spatial shape of galaxies (oblate spheroid or triaxial ellipsoid) on the
+dynamics, as well as the structure of the internal density layers in these
+systems. For each galaxy the ratio of the rotational energy to the potential
+energy was found. Comparing this ratio with the observed it is concluded that
+the majority of these systems cannot have isotropic velocity dispersion
+tensors. The anisotropy parameter limited to the interval 0.0-0.224. A
+correlation was found between and flattening of the outer regions for giant
+E-galaxies. Our results are compared with the results of other researchers. It
+was found that for small fast rotators our values \b{eta} are in good agreement
+with those, obtained in the ATLAS project. However, for giant E-galaxies, our
+models provide better agreement with observations, than axisymmetric JAM
+models. In addition, our velocity dispersion anisotropy results are in
+satisfactory agreement with the results of high resolution cosmological
+simulations in the Illustris project",2001.04094v1
+2020-02-06,"Effects of transition-metal spacers on the spin-orbit torques, spin Hall magnetoresistance, and magnetic anisotropy of Pt/Co bilayers","We studied the effect of inserting 0.5 nm-thick spacer layers (Ti, V, Cr, Mo,
+W) at the Pt/Co interface on the spin-orbit torques, Hall effect,
+magnetoresistance, saturation magnetization, and magnetic anisotropy. We find
+that the damping-like spin-orbit torque decreases substantially for all samples
+with a spacer layer compared to the reference Pt/Co bilayer, consistently with
+the opposite sign of the atomic spin-orbit coupling constant of the spacer
+elements relative to Pt. The reduction of the damping-like torque is monotonic
+with atomic number for the isoelectronic 3d, 4d, and 5d elements, with the
+exception of V that has a stronger effect than Cr. The field-like spin-orbit
+torque almost vanishes for all spacer layers irrespective of their composition,
+suggesting that this torque predominantly originates at the Pt/Co interface.
+The anomalous Hall effect, magnetoresistance, and saturation magnetization are
+also all reduced substantially, whereas the sheet resistance is increased in
+the presence of the spacer layer. Finally, we evidence a correlation between
+the amplitude of the spin-orbit torques, the spin Hall-like magnetoresistance,
+and the perpendicular magnetic anisotropy. These results highlight the
+significant influence of ultrathin spacer layers on the magnetotransport
+properties of heavy metal/ferromagnetic systems.",2002.02162v1
+2020-02-10,Joule-Thomson Expansion of Regular Bardeen AdS Black Hole Surrounded by Static Anisotropic Quintessence Field,"In the present paper, we investigate the required anisotropy of an exact
+regular Bardeen black hole characterized by its mass $M$, the nonlinear
+parameter $g$, the quintessence field parameter $a$ in anti-de sitter spacetime
+with a static quintessence matter field. We also show that the relative
+pressure anisotropy, equation of state and the pressure depends on radial
+coordinate, reflecting the required anisotropy for Bardeen black hole in the
+quintessence background.
+  Next, we analyze the Joule-Thompson ($JT$) expansion of the black hole
+spacetime. Treating the cosmological constant as thermodynamic pressure $P$ and
+its conjugate quantity as thermodynamic volume $V$ we derive the equation of
+state connecting Hawking temperature and various black hole parameters. We
+study the $JT$ expansion in the regular Bardeen AdS black holes in the
+quintessence background through the analysis of inversion temperature and
+isenthalpic curves. We derive the $JT$ coefficient $\mu$, and use them to plot
+the inversion and isenthalpic curves. We discuss the effect of quintessence
+parameter $a$ and $\omega_q$ on the $JT$ coefficient and inversion temperature,
+especially with the case of $\omega_q=-1$ and $\omega_q=-\frac{1}{3}$. Our
+analysis shows that quintessence dark energy affects the inversion point
+$(T_i,P_i)$ .",2002.03634v1
+2020-03-19,Anisotropy of the Upper Critical Field in the Heavy-Fermion Superconductor UTe2 under Pressure,"We studied the anisotropy of the superconducting upper critical field $H_{\rm
+c2}$ in the heavy-fermion superconductor UTe$_2$ under hydrostatic pressure by
+magnetoresistivity measurements. In agreement with previous experiments we
+confirm that superconductivity disappears near a critical pressure $p_{\rm c}
+\approx 1.5$~GPa, and a magnetically ordered state appears. The unusual $H_{\rm
+c2}(T)$ at low temperatures for $H \parallel a$ suggests that the multiple
+superconducting phases which appear under pressure have quite different $H_{\rm
+c2}$. For a field applied along the hard magnetization $b$ axis $H_{\rm c2}
+(0)$ is glued to the metamagnetic transition $H_{\rm m}$ which is suppressed
+near $p_{\rm c}$. The suppression of $H_{\rm m}$ with pressure follows the
+decrease of temperature $T_{\chi}^{\rm max}$, at the maximum in the
+susceptibility along $b$. The strong reinforcement of $H_{\rm c2}$ at ambient
+pressure for $H \parallel b$ above 16~T is rapidly suppressed under pressure
+due to the increase of $T_{\rm sc}$ and the decrease of $H_{\rm m}$. The change
+in the hierarchy of the anisotropy of $H_{\rm c2}(0)$ on approaching $p_{\rm
+c}$ points out that the $c$ axis becomes the hard magnetization axis.",2003.08728v1
+2020-03-28,Bianchi I metric solutions with nonminimally coupled Einstein-Maxwell gravity theory,"By using Bianchi I type of homogenous and anisotropic background metric
+having cylindrical symmetry in $x$ direction of a local cartesian coordinates
+system, we solve metric field equations for a non-minimally coupled
+Einstein-Maxwell gravity. To do so we choose long wavelength EM waves where
+spatial dependence of the waves are negligible at the expansion duration.
+Motivation of this work is study directional effects of the EM vector potential
+on anisotropy trajectory of the space time expansion scale factor. This problem
+is checked just for de Sitter inflationary epoch because of its importance in
+the expansion of the universe. By applying the dynamical system approach we
+investigate stability nature of the cosmic system in two different cases: (a)
+direction of the EM vector potential is parallel to $x$ direction of the
+spacetime and (b) it is perpendicular to $x$ direction. We obtained at stable
+critical points for some of obtained inflationary solutions the EM waves behave
+as dark energy in cases $a$ and $b$ where the anisotropy is negligible by
+expanding of the universe while there are some stable critical points with
+inflationary stable solutions in case $b$ for which the EM waves behave as
+baryonic visible matter with non-vanishing anisotropy.",2003.14216v4
+2020-03-31,Magnetic properties of Co/Ni-based multilayers with Pd and Pt insertion layers,"In this study, the influence of Pd and Pt insertion layers in Co/Ni
+multilayers (MLs) on their magnetic properties, e.g. magnetic anisotropies,
+saturation magnetization, coercivity, magnetic domain size, and Curie
+temperature, is investigated. We compare three series of [Co/Ni/X]N ML systems
+(X = Pd, Pt, no insertion layer), varying the individual Co layer thickness as
+well as the repetition number N. All three systems behave very similarly for
+the different Co layer thicknesses. For all systems, a maximum effective
+magnetic anisotropy was achieved for MLs with a Co layer thickness between 0.15
+nm and 0.25 nm. The transition from an out-of-plane to an in-plane system
+occurs at about 0.4 nm of Co. While [Co(0.2 nm)/Ni(0.4 nm)]N MLs change their
+preferred easy magnetization axis from out-of-plane to in-plane after 6 bilayer
+repetitions, insertion of Pd and Pt results in an extension of this transition
+beyond 15 repetitions. The maximum effective magnetic anisotropy was more than
+doubled from 105 kJ/m3 for [Co/Ni]3 to 275 and 186 kJ/m3 for Pt and Pd,
+respectively. Furthermore, the insertion layers strongly reduce the initial
+saturation magnetization of 1100 kA/m of Co/Ni MLs and lower the Curie
+temperature from 720 to around 500 K",2003.14306v1
+2020-04-07,Laser-induced magnetization precession in individual magnetoelastic domains of a multiferroic CoFeB/BaTiO$_3$ composite,"Using a magneto-optical pump-probe technique with micrometer spatial
+resolution we show that magnetization precession can be launched in individual
+magnetic domains imprinted in a Co$_{40}$Fe$_{40}$B$_{20}$ (CoFeB) layer by
+elastic coupling to ferroelectric domains in a BaTiO$_{3}$ substrate. The
+dependence of the precession parameters on external magnetic field strength and
+orientation reveal that by laser-induced ultrafast partial quenching of the
+magnetoelastic coupling parameter of CoFeB by $\approx$27% along with 10%
+ultrafast demagnetization trigger the magnetization precession. The relation
+between the laser-induced reduction of the magnetoelastic coupling and the
+demagnetization is approximated by the $n(n+1)/2$-law with n$\approx$2. This
+correspondence confirms the thermal origin of the laser-induced anisotropy
+change. Based on the analysis and modeling of the excited precession we find
+signatures of laser-induced precessional switching, which occurs when the
+magnetic field is applied along the hard magnetization axis and its value is
+close to the effective magnetoelastic anisotropy field. The precession
+excitation process in an individual magnetoelastic domain is found to be
+unaffected by neighboring domains. This makes laser-induced changes of
+magnetoelastic anisotropy a promising tool for driving magnetization dynamics
+and switching in composite multiferroics with spatial selectivity.",2004.03566v5
+2020-04-14,"On the Elastic Anisotropy of the Entropy-Stabilized Oxide (Mg, Co, Ni, Cu, Zn)O","In this paper, we study the elastic properties of the entropy-stabilized
+oxide (Mg, Co, Ni, Cu, Zn)O, using experimental and first principles
+techniques. Our measurements of the indentation modulus on grains with a wide
+range of crystallographic orientations of the entropy-stabilized oxide revealed
+a high degree of elastic isotropy at ambient conditions. First principles
+calculations predict mild elastic anisotropy for the paramagnetic structure,
+which decreases when the system is considered to be non-magnetic. When the
+antiferromagnetic state of CoO, CuO and NiO is accounted for in the
+calculations, a slight increase in the elastic anisotropy is observed,
+suggesting a coupling between magnetic ordering and the orientation dependent
+elastic properties. Furthermore, an examination of the local structure reveals
+that the isotropy is favored through local ionic distortions of Cu and Zn - due
+to their tendency to form tenorite and wurtzite phases. The relationships
+between the elastic properties of the multicomponent oxide and those of its
+constituent binary oxides are reviewed. These insights open up new avenues for
+controlling isotropy for technological applications through tuning composition
+and structure in the entropy-stabilized oxide or the high entropy compounds in
+general.",2004.06613v1
+2020-04-23,Temperature-dependent Magnetic Transitions in CoCrPt-Ru-CoCrPt Synthetic Ferrimagnets,"The magnetic orientations and switching fields of a CoCrPt-Ru-CoCrPt
+synthetic ferrimagnet with perpendicular magnetic anisotropy have been studied
+in the temperature range from 2 K to 300 K. It was found that two sets of
+magnetic transitions occur in the CoCrPt-Ru-CoCrPt ferrimagnet across this
+temperature range. The first set exhibits three magnetic transitions in the 50
+K - 370 K range, whereas the second involves only two transitions in the 2 K
+and 50 K range. The observed magnetic hysteresis curves of the synthetic
+ferrimagnet are explained using the energy diagram technique framework
+pioneered by Koplak et al. [1] which accurately describes the competition
+between interlayer exchange coupling energy, Zeeman energy, and anisotropy
+energy in the system. In this work we expand the framework to include synthetic
+ferrimagnets (SFMs) comprising higher perpendicular magnetic anisotropy
+materials and large (4X) interlayer exchange coupling energies which are
+promising for the development of ultrafast (ps) magnetic switching free layers
+in MTJ structures. Furthermore, we apply the analysis to predict SFM magnetic
+hysteresis curves in a temperature regime that includes temperature extrema
+that a synthetic ferrimagnet would be expected to reliably operate at, were it
+to be utilized as a free layer in a memory or sensor spintronic device.",2004.11406v2
+2020-05-07,Broadband strong optical dichroism in topological Dirac semimetals with Fermi velocity anisotropy,"Prototypical three-dimensional (3D) topological Dirac semimetals (DSMs), such
+as Cd$_3$As$_2$ and Na$_3$Bi, contain electrons that obey a linear
+momentum-energy dispersion with different Fermi velocities along the three
+orthogonal momentum dimensions. Despite being extensively studied in recent
+years, the inherent \emph{Fermi velocity anisotropy} has often been neglected
+in the theoretical and numerical studies of 3D DSMs. Although this omission
+does not qualitatively alter the physics of light-driven massless
+quasiparticles in 3D DSMs, it does \emph{quantitatively} change the optical
+coefficients which can lead to nontrivial implications in terms of
+nanophotonics and plasmonics applications. Here we study the linear optical
+response of 3D DSMs for general Fermi velocity values along each direction.
+Although the signature conductivity-frequency scaling, $\sigma(\omega) \propto
+\omega$, of 3D Dirac fermion is well-protected from Fermi velocity anisotropy,
+the linear optical response exhibits strong linear dichroism as captured by the
+\emph{universal} extinction ratio scaling law, $\Lambda_{ij} = (v_i/v_j)^2$
+(where $i\neq j$ denotes the three spatial coordinates $x,y,z$, and $v_i$ is
+the $i$-direction Fermi velocity), which is independent of frequency,
+temperature, doping, and carrier scattering lifetime. For Cd$_3$As$_2$ and
+Na$_3$Bi$_3$, an exceptionally strong extinction ratio larger than 15 and
+covering broad terahertz window is revealed. Our findings shed new light on the
+role of Fermi velocity anisotropy in the optical response of Dirac semimetals
+and open up novel polarization-sensitive functionalities, such as
+photodetection and light modulation.",2005.03363v1
+2020-05-18,"Effects of filling, strain, and electric field on the Néel vector in antiferromagnetic CrSb","CrSb is a layered antiferromagnet (AFM) with perpendicular magnetic
+anisotropy, a high N\'{e}el temperature, and large spin-orbit coupling (SOC),
+which makes it interesting for AFM spintronic applications. To elucidate the
+various mechanisms of N\'{e}el vector control, the effects of strain, band
+filling, and electric field on the magnetic anisotropy energy (MAE) of bulk and
+thin-film CrSb are determined and analysed using density functional theory. The
+MAE of the bulk crystal is large (1.2 meV per unit cell). Due to the
+significant ionic nature of the Cr-Sb bond, finite slabs are strongly affected
+by end termination. Truncation of the bulk crystal to a thin film with one
+surface terminated with Cr and the other surface terminated with Sb breaks
+inversion symmetry, creates a large charge dipole and average electric field
+across the film, and breaks spin degeneracy, such that the thin film becomes a
+ferrimagnet. The MAE is reduced such that its sign can be switched with
+realistic strain, and the large SOC gives rise to an intrinsic voltage
+controlled magnetic anisotropy (VCMA). A slab terminated on both faces with Cr
+remains a compensated AFM, but with the compensation occurring nonlocally
+between mirror symmetric Cr pairs. In-plane alignment of the moments is
+preferred, the magnitude of the MAE remains large, similar to that of the bulk,
+and it is relatively insensitive to filling.",2005.08412v5
+2020-05-18,On problematic case of product approximation in Backus average,"Elastic anisotropy might be a combined effect of the intrinsic anisotropy and
+the anisotropy induced by thin-layering. The Backus average, a useful
+mathematical tool, allows us to describe such an effect quantitatively. The
+results are meaningful only if the underlying physical assumptions are obeyed,
+such as static equilibrium of the material. We focus on the only mathematical
+assumption of the Backus average, namely, product approximation. It states that
+the average of the product of a varying function with nearly-constant function
+is approximately equal to the product of the averages of those functions. We
+discuss particular, problematic case for which the aforementioned assumption is
+inaccurate. Further, we focus on the seismological context. We examine
+numerically if the inaccuracy affects the wave propagation in a homogenous
+medium -- obtained using the Backus average -- equivalent to thin layers. We
+take into consideration various material symmetries, including orthotropic,
+cubic, and others. We show that the problematic case of product approximation
+is strictly related to the negative Poisson's ratio of constituent layers.
+Therefore, we discuss the laboratory and well-log cases in which such a ratio
+has been noticed. Upon thorough literature review, it occurs that examples of
+so-called auxetic materials (media that have negative Poisson's ratio) are not
+extremely rare exceptions as thought previously. The investigation and
+derivation of Poisson's ratio for materials exhibiting symmetry classes up to
+monoclinic become a significant part of this paper. Except for the main
+objectives, we also show that the averaging of cubic layers results in an
+equivalent medium with tetragonal (not cubic) symmetry. Additionally, we
+present concise formulations of stability conditions for low symmetry classes,
+such as trigonal, orthotropic, and monoclinic.",2005.08677v2
+2020-05-25,Optimal Boltzmann hierarchies with non-vanishing spatial curvature,"Within cosmological perturbation theory, the cosmic microwave background
+anisotropies are usually computed from a Boltzmann hierarchy coupled to the
+perturbed Einstein equations. In this setup, one set of multipoles describes
+the temperature anisotropies, while two other sets, of electric and magnetic
+types, describe the polarization anisotropies. In order to reduce the number of
+multipoles types needed for polarization, and thus to speed up the numerical
+resolution, an optimal hierarchy has been proposed in the literature for
+Einstein-Boltzmann codes. However, it has been recently shown that the
+separability between directional and orbital eigenfunctions employed in the
+optimal hierarchy is not correct in the presence of spatial curvature. We
+investigate how the assumption of separability affects the optimal hierarchy,
+and show that it introduces relative errors of order $\Omega_K$ with respect to
+the full hierarchy. Despite of that, we show that the optimal hierarchy still
+gives extremely good results for temperature and polarization angular spectra,
+with relative errors that are much smaller than cosmic variance even for
+curvatures as large as $|\Omega_K|=0.1$. Still, we find that the polarization
+angular spectra from tensor perturbations are significantly altered when using
+the optimal hierarchy, leading to errors that are typically of order $50
+|\Omega_K| \%$ on that component.",2005.12119v1
+2020-05-29,Long-distance spin-transport across the Morin phase transition up to room temperature in ultra-low damping single crystals of the antiferromagnet α-Fe2O3,"Antiferromagnetic materials can host spin-waves with polarizations ranging
+from circular to linear depending on their magnetic anisotropies. Until now,
+only easy-axis anisotropy antiferromagnets with circularly polarized spin-waves
+were reported to carry spin-information over long distances of micrometers. In
+this article, we report long-distance spin-transport in the easy-plane canted
+antiferromagnetic phase of hematite and at room temperature, where the linearly
+polarized magnons are not intuitively expected to carry spin. We demonstrate
+that the spin-transport signal decreases continuously through the easy-axis to
+easy-plane Morin transition, and persists in the easy-plane phase through
+current induced pairs of linearly polarized magnons with dephasing lengths in
+the micrometer range. We explain the long transport distance as a result of the
+low magnetic damping, which we measure to be below 0.0001 as in the best
+ferromagnets. All of this together demonstrates that long-distance transport
+can be achieved across a range of anisotropies and temperatures, up to room
+temperature, highlighting the promising potential of this insulating
+antiferromagnet for magnon-based devices.",2005.14414v5
+2020-05-29,Direction-sensitive magnetophotonic surface crystal,"Nanometer-thin rare-earth-transition metal (RE-TM) alloys with precisely
+controlled compositions and out-of-plane magnetic anisotropy are currently in
+the focus for ultrafast magnetophotonic applications. However, achieving
+lateral nanoscale dimensions, crucial for potential device downscaling, while
+maintaining designable optomagnetic functionality and out-of-plane magnetic
+anisotropy is extremely challenging. Here we integrate nanosized
+Tb$_{18}$Co$_{82}$ ferrimagnetic alloys, having strong out-of-plane magnetic
+anisotropy, within a gold plasmonic nanoantenna array to design
+micrometer-scale a magnetophotonic crystal that exhibit abrupt and narrow
+magneto-optical spectral features that are both magnetic field and light
+incidence direction controlled. The narrow Fano-type resonance arises through
+the interference of the individual nanoantenna's surface plasmons and a
+Rayleigh anomaly of the whole nanoantenna array, in both optical and
+magneto-optical spectra, which we demonstrate and explain using Maxwell-theory
+simulations. This robust magnetophotonic crystal opens the way for conceptually
+new high-resolution light incidence direction sensors, as well as for building
+blocks for plasmon-assisted all-optical magnetization switching in
+ferrimagnetic RE-TM alloys.",2005.14478v3
+2020-06-10,Study of magnetic interface and its effect in Fe/NiFe bilayers of alternating order,"We present a comprehensive study on the magnetization reversal in Fe/NiFe
+bilayer system by alternating the order of the magnetic layers. All the samples
+show growth-induced uniaxial magnetic anisotropy due to oblique angle
+deposition technique. Strong interfacial exchange coupling between the Fe and
+NiFe layers leads to the single-phase hysteresis loops in the bilayer system.
+The strength of coupling being dependent on the interface changes upon
+alternating the order of magnetic layers. The magnetic parameters such as
+coercivity HC, and anisotropy field HK become almost doubled when NiFe layer is
+grown over the Fe layers. This enhancement in the magnetic parameters is
+primarily dependent on the increase of the thickness and magnetic moment of
+Fe-NiFe interfacial layer as revealed from the polarized neutron reectivity
+(PNR) data of the bilayer samples. The difference in the thickness and
+magnetization of the Fe-NiFe interfacial layer indicates the modification of
+the microstructure by alternating the order of the magnetic layers of the
+bilayers. The interfacial magnetic moment increased by almost 18 % when NiFe
+layer is grown over the Fe layer. In spite of the different values of
+anisotropy fields and modified interfacial exchange coupling, the Gilbert
+damping constant values of the ferromagnetic bilayers remain similar to single
+NiFe layer.",2006.05756v1
+2020-06-25,Perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction at an oxide/ferromagnetic metal interface,"We report on the study of both perpendicular magnetic anisotropy (PMA) and
+Dzyaloshinskii-Moriya interaction (DMI) at an oxide/ferromagnetic metal (FM)
+interface, i.e. BaTiO3 (BTO)/CoFeB. Thanks to the functional properties of the
+BTO film and the capability to precisely control its growth, we are able to
+distinguish the dominant role of the oxide termination (TiO2 vs BaO), from the
+moderate effect of ferroelectric polarization in the BTO film, on the PMA and
+DMI at the oxide/FM interface. We find that the interfacial magnetic anisotropy
+energy of the BaO-BTO/CoFeB structure is two times larger than that of the
+TiO2-BTO/CoFeB, while the DMI of the TiO2-BTO/CoFeB interface is larger. We
+explain the observed phenomena by first-principles calculations, which ascribe
+them to the different electronic states around the Fermi level at the
+oxide/ferromagnetic metal interfaces and the different spin-flip processes.
+This study paves the way for further investigation of the PMA and DMI at
+various oxide/FM structures and thus their applications in the promising field
+of energy-efficient devices.",2006.14268v1
+2020-07-12,Anisotropic Kondo screening induced by spin-orbit coupling in quantum wires,"Using the numerical renormalization group (NRG) method we study a magnetic
+impurity coupled to a quantum wire with Rashba and Dresselhaus spin-orbit
+coupling (SOC) in an external magnetic field. We consider the low-filling
+regime with the Fermi energy close to the bottom of the band and report the
+results for local static and dynamic properties in the Kondo regime. In the
+absence of the field, local impurity properties remain isotropic in spin space
+despite the SOC-induced magnetic anisotropy of the conduction band. In the
+presence of the field, clear fingerprints of anisotropy are revealed through
+the strong field-direction dependence of the impurity spin polarization and
+spectra, in particular of the Kondo peak height. The detailed behavior depends
+on the relative magnitudes of the impurity and band $g$-factors. For the case
+of impurity $g$-factor somewhat lower than the band $g$-factor, the maximal
+Kondo peak suppression is found for field oriented along the effective SOC
+field axis, while for a field perpendicular to this direction we observe a
+compensation effect (``revival of the Kondo peak''): the SOC counteracts the
+Kondo peak splitting effects of the local Zeeman field. We demonstrate that the
+SOC-induced anisotropy, measurable by tunneling spectroscopy techniques, can
+help to determine the ratio of Rashba and Dresselhaus SOC strengths in the
+wire.",2007.06044v1
+2020-07-21,Gamma-ray and radio background constraints on cosmic rays in Milky Way circumgalactic medium,"We study the interaction of cosmic rays (CRs) with the diffuse circumgalactic
+gas of Milky Way (MW) galaxy that results in hadronic $\gamma-$ray emission and
+radio synchrotron emission. We aim to constrain the CR population in our
+circumgalactic medium (CGM) with the help of observed isotropic $\gamma$-ray
+background (IGRB), its anisotropy and radio continuum. We modify different
+models of CGM gas in hydrostatic equilibrium discussed in literature by
+including a cosmic ray population, parametrized by $\eta \equiv P_{\rm
+CR}/P_{\rm th}$. For the simplest isothermal model, while the IGRB intensity
+allows $\eta \lesssim 3$, the anisotropy resulting from the Solar system's
+off-center position in MW rules out all values of $\eta$. For the precipitation
+model, in which the cooling of the CGM gas is regulated with an optimum ratio
+of cooling time to free-fall time,while the observed IGRB intensity allows
+$\eta \lesssim 230$, the observed anisotropy allows only very large values of
+$\eta$, of order $\gtrsim 100$. The radio continuum limits $\eta \lesssim 400$
+for precipitation model and does not constrain isothermal model, however these
+constraints are mitigated by synchrotron loss time being comparable to CR
+diffusion time scales. These bounds are relevant for current numerical
+simulations that indicate a significant CR population in CGM of galaxies of MW
+mass.",2007.11015v2
+2020-08-02,Tailoring Magnetism in Self-intercalated Cr1+δTe2 Epitaxial Films,"Magnetic transition metal dichalcogenide (TMD) films have recently emerged as
+promising candidates to host novel magnetic phases relevant to next-generation
+spintronic devices. However, systematic control of the magnetization
+orientation, or anisotropy, and its thermal stability, characterized by Curie
+temperature (Tc) remains to be achieved in such films. Here we present
+self-intercalated epitaxial Cr1+{\delta}Te2 films as a platform for achieving
+systematic/smooth magnetic tailoring in TMD films. Using a molecular beam
+epitaxy (MBE) based technique, we have realized epitaxial Cr1+{\delta}Te2 films
+with smoothly tunable over a wide range (0.33-0.82), while maintaining
+NiAs-type crystal structure. With increasing {\delta}, we found monotonic
+enhancement of Tc from 160 to 350 K, and the rotation of magnetic anisotropy
+from out-of-plane to in-plane easy axis configuration for fixed film thickness.
+Contributions from conventional dipolar and orbital moment terms are
+insufficient to explain the observed evolution of magnetic behavior with
+{\delta}. Instead, ab initio calculations suggest that the emergence of
+antiferromagnetic interactions with {\delta}, and its interplay with
+conventional ferromagnetism, may play a key role in the observed trends. To our
+knowledge, this constitutes the first demonstration of tunable Tc and magnetic
+anisotropy across room temperature in TMD films, and paves the way for
+engineering novel magnetic phases for spintronic applications.",2008.00381v1
+2020-08-18,Probing solar flare accelerated electron distributions with prospective X-ray polarimetry missions,"Solar flare electron acceleration is an extremely efficient process, but the
+method of acceleration is not well constrained. Two of the essential
+diagnostics: electron anisotropy (velocity angle to the guiding magnetic field)
+and the high energy cutoff (highest energy electrons produced by the
+acceleration conditions: mechanism, spatial extent, time), are important
+quantities that can help to constrain electron acceleration at the Sun but both
+are poorly determined. Here, using electron and X-ray transport simulations
+that account for both collisional and non-collisional transport processes such
+as turbulent scattering, and X-ray albedo, we show that X-ray polarization can
+be used to constrain the anisotropy of the accelerated electron distribution
+and the most energetic accelerated electrons together. Moreover, we show that
+prospective missions, e.g. CubeSat missions without imaging information, can be
+used alongside such simulations to determine these parameters. We conclude that
+a fuller understanding of flare acceleration processes will come from missions
+capable of both X-ray flux and polarization spectral measurements together.
+Although imaging polarimetry is highly desired, we demonstrate that
+spectro-polarimeters without imaging can also provide strong constraints on
+electron anisotropy and the high energy cutoff.",2008.07849v2
+2020-08-27,Study of Transverse Spherocity and Azimuthal Anisotropy in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV using A Multi-Phase Transport Model,"Transverse spherocity is an event shape observable having a very unique
+capability to separate the events based on their geometrical shapes. Recent
+results from experiments at the LHC suggest that transverse spherocity is an
+important event classifier in small collision systems. In this work, we use
+transverse spherocity for the first time in heavy-ion collisions and perform an
+extensive study on azimuthal anisotropy of charged particles produced in Pb-Pb
+collisions at $\sqrt{s_{\rm{NN}}} = 5.02$ TeV using A Multi-Phase Transport
+Model (AMPT). The azimuthal anisotropy is estimated using the 2-particle
+correlation method, which suppresses the non-flow effects significantly with an
+appropriate pseudorapidity gap of particle pairs. The results from AMPT are
+compared with estimations from PYTHIA8 (Angantyr) model and it is found that
+with the chosen pseudorapidity gap the residual non-flow effects become
+negligible. We found that the high spherocity events have nearly zero elliptic
+flow while low spherocity events contribute significantly to elliptic flow of
+spherocity-integrated events. Our studies indicate that using transverse
+spherocity in heavy-ion collisions, one can enhance and/or suppress the
+collective effects.",2008.13616v2
+2020-09-03,First-principles study on structure and anisotropy of high N-atom density layer in 4H-SiC,"A nitridation annealing process is well employed to reduce interface trap
+states that degrade the channel mobility of 4H-SiC/SiO${}_2$
+metal-oxide-semiconductor field-effect transistor. In recent experiments, the
+existence of high N-atom density layers at the annealed interface is reported
+and their concentrations are known to be anisotropic in the crystal planes.
+Until now, the role of atomic structure and the electronic states surrounding
+the N atoms incorporated by the nitridation annealing process on the origin of
+anisotropy is not well understood. In this work, we propose a simplified
+atomic-scale model structure of 4H-SiC with the a high N-atom density layer
+($\sim 10^{15}~\mathrm{atom}/\mathrm{cm}^2$), which is of the order of the
+experimental observation. We use bulk 4H-SiC as host crystal and consider
+several sets of the atomic configurations of the N-atom incorporated structure
+at the quasi cubic-($k$-) and hexagonal-($h$-)sites on $a$-, $m$-, and
+Si-(C-)planes. Based on the density functional theory calculations, we
+investigate the influence of the energy stability on the distribution
+directions. Although our bulk model is simplified compared to the realistic
+interface structures, we confirm significant difference among models and
+observe that the incorporation of N atoms on the $a$-face is stable.
+Furthermore, from the analysis of the electronic states, we suggest that this
+anisotropy of the formation energy originates from the change of the
+coordinating number due to the difference in geometric configurations of the
+N-atom incorporated structures.",2009.01627v4
+2020-09-14,Screening anisotropy via energy-momentum squared gravity: $Λ$CDM model with hidden anisotropy,"We construct a generalization of the standard $\Lambda$CDM model, wherein we
+simultaneously replace the spatially flat Robertson-Walker metric with its
+simplest anisotropic generalization (LRS Bianchi I metric), and couple the cold
+dark matter to the gravity in accordance with the energy-momentum squared
+gravity (EMSG) of the form $f(T_{\mu\nu}T^{\mu\nu})\propto
+T_{\mu\nu}T^{\mu\nu}$. These two modifications -- namely, two new stiff
+fluid-like terms of different nature -- can mutually cancel out, i.e., the
+shear scalar can be screened completely, and reproduce mathematically exactly
+the same Friedmann equation of the standard $\Lambda$CDM model. This evades the
+BBN limits on the anisotropy, and thereby provides an opportunity to manipulate
+the cosmic microwave background quadrupole temperature fluctuation at the
+desired amount. We further discuss the consequences of the model on the very
+early times and far future of the Universe. This study presents also an example
+of that the EMSG of the form $f(T_{\mu\nu}T^{\mu\nu})\propto
+T_{\mu\nu}T^{\mu\nu}$, as well as similar type other constructions, is not
+necessarily relevant only to very early Universe but may even be considered in
+the context of a major problem of the current cosmology related to the
+present-day Universe, the so-called $H_0$ problem.",2009.06517v2
+2020-09-22,Magnon-mediated spin currents in Tm3Fe5O12/Pt with perpendicular magnetic anisotropy,"The control of pure spin currents carried by magnons in magnetic insulator
+(MI) garnet films with a robust perpendicular magnetic anisotropy (PMA) is of
+great interest to spintronic technology as they can be used to carry, transport
+and process information. Garnet films with PMA present labyrinth domain
+magnetic structures that enrich the magnetization dynamics, and could be
+employed in more efficient wave-based logic and memory computing devices. In
+MI/NM bilayers, where NM being a normal metal providing a strong spin-orbit
+coupling, the PMA benefits the spin-orbit torque (SOT) driven magnetization's
+switching by lowering the needed current and rendering the process faster,
+crucial for developing magnetic random-access memories (SOT-MRAM). In this
+work, we investigated the magnetic anisotropies in thulium iron garnet (TIG)
+films with PMA via ferromagnetic resonance measurements, followed by the
+excitation and detection of magnon-mediated pure spin currents in TIG/Pt driven
+by microwaves and heat currents. TIG films presented a Gilbert damping constant
+{\alpha}~0.01, with resonance fields above 3.5 kOe and half linewidths broader
+than 60 Oe, at 300 K and 9.5 GHz. The spin-to-charge current conversion through
+TIG/Pt was observed as a micro-voltage generated at the edges of the Pt film.
+The obtained spin Seebeck coefficient was 0.54 {\mu}V/K, confirming also the
+high interfacial spin transparency.",2009.10299v1
+2020-09-27,Effects of spatially-varying substrate anchoring on instabilities and dewetting of thin Nematic Liquid Crystal films,"Partially wetting nematic liquid crystal (NLC) films on substrates are
+unstable to dewetting-type instabilities due to destablizing solid/NLC
+interaction forces. These instabilities are modified by the nematic nature of
+the films, which influences the effective solid/NLC interaction. In this work,
+we focus on the influence of imposed substrate anchoring on the instability
+development. The analysis is carried out within a long-wave formulation based
+on the Leslie-Ericksen description of NLC films. Linear stability analysis of
+the resulting equations shows that some features of the instability, such as
+emerging wavelengths, may not be influenced by the imposed substrate anchoring.
+Going further into the nonlinear regime, considered via large-scale GPU-based
+simulations, shows however that nonlinear effects may play an important role,
+in particular in the case of strong substrate anchoring anisotropy. Our
+simulations show that instability of the film develops in two stages: the first
+stage involves formation of ridges that are perpendicular to the local
+anchoring direction; and the second involves breakup of these ridges and
+formation of drops, whose final distribution is influenced by the anisotropy
+imposed by the substrate. Finally, we show that imposing more complex substrate
+anisotropy patterns allows us to reach basic understanding of the influence of
+substrate-imposed defects in director orientation on the instability evolution.",2009.12946v1
+2020-11-02,Compact stellar model in Tolman space-time in presence of pressure anisotropy,"In this paper, we develop a new relativistic compact stellar model for a
+spherically symmetric anisotropic matter distribution. The model has been
+obtained through generating a new class of solutions by invoking the Tolman
+{\em ansatz} for one of the metric potentials $g_{rr}$ and a physically
+reasonable selective profile of radial pressure. We have matched our obtained
+interior solution to the Schwarzschild exterior spacetime over the bounding
+surface of the compact star. These matching conditions together with the
+condition of vanishing the radial pressure across the boundary of the star have
+been utilized to determine the model parameters. We have shown that the central
+pressure of the star depends on the parameter $p_0$. We have estimated the
+range of $p_0$ by using the recent data of compact stars 4U 1608-52 and Vela
+X-1. The effect of $p_0$ on different physical parameters e.g., pressure
+anisotropy, the subliminal velocity of sound, relativistic adiabatic index etc.
+have also been discussed. The developed model of the compact star is
+elaborately discussed both analytically and graphically to justify that it
+satisfies all the criteria demanded a realistic star. From our analysis, we
+have shown that the effect of anisotropy becomes small for higher values of
+$p_0$. The mass-radius (M-R) relationship which indicates the maximum mass
+admissible for observed pulsars for a given surface density has also been
+investigated in our model. Moreover, the variation of radius and mass with
+central density has been shown which allow us to estimate central density for a
+given radius (or mass) of a compact star.",2011.00856v2
+2020-11-23,Primordial non-Gaussianity from the Effects of the Standard Model Higgs during Reheating after Inflation,"We propose a new way of studying the Higgs potential at extremely high
+energies. The Standard Model (SM) Higgs boson, as a light spectator field
+during inflation in the early Universe, can acquire large field values from its
+quantum fluctuations which vary among different causal (Hubble) patches. Such a
+space dependence of the Higgs after the end of inflation leads to
+space-dependent SM particle masses and hence variable efficiency of reheating,
+when the inflaton decays to Higgsed SM particles. Inhomogeneous reheating
+results in (observable) temperature anisotropies. Further, the resulting
+temperature anisotropy spectrum acquires a significant non-Gaussian component,
+which is constrained by $\textit{Planck}$ observations of the Cosmic Microwave
+Background (CMB) and potentially detectable in next-generation experiments.
+Constraints on this non-Gaussian signal largely exclude the possibility of the
+observed temperature anisotropies arising primarily from Higgs effects. Hence,
+in principle, observational searches for non-Gaussianity in the CMB can be used
+to constrain the dynamics of the Higgs boson at very high (inflationary)
+energies.",2011.11649v3
+2020-11-25,No Stagnation Region Before the Heliopause at Voyager 1? Inferences From New Voyager 2 Results,"We present anisotropy results for anomalous cosmic-ray (ACR) protons in the
+energy range $\sim$0.5-35 MeV from Cosmic Ray Subsytem (CRS) data collected
+during calibration roll maneuvers for the magnetometer instrument when Voyager
+2 (V2) was in the inner heliosheath. We use a new technique to derive for the
+first time the radial component of the anisotropy vector from CRS data. We find
+that the CRS-derived radial solar wind speeds, when converted from the radial
+components of the anisotropy vectors via the Compton-Getting (C-G) effect,
+generally agree with those similarly-derived speeds from the Low-Energy Charged
+Particle experiment using 28-43 keV data. However, they often differ
+significantly from the radial solar wind speeds measured directly by the Plasma
+Science (PLS) instrument. There are both periods when the C-G-derived radial
+solar wind speeds are significantly higher than those measured by PLS and times
+when they are significantly lower. The differences are not expected nor
+explained, but it appears that after a few years in the heliosheath the V2
+radial solar wind speeds derived from the C-G method underestimate the true
+speeds as the spacecraft approaches the heliopause. We discuss the implications
+of this observation for the stagnation region reported along the Voyager 1
+trajectory as it approached the heliopause inferred using the C-G method.",2011.12926v1
+2021-01-09,Dipolar Interaction and Sample Shape Effects on the Hysteresis Properties of 2d Array of Magnetic Nanoparticles,"We study the ground state and magnetic hysteresis properties of 2$d$ arrays
+($L^{}_x\times L^{}_y$) of dipolar interacting magnetic nanoparticles (MNPs) by
+performing micromagnetic simulations. Our primary interest is to understand the
+effect of sample shape, $\Theta$- the ratio of the dipolar strength to the
+anisotropy strength, and the direction of the applied field $\vec{H} =
+H_{o}\hat{e}^{}_H$ on the ground state and the magnetic hysteresis in an array
+of MNPs. To study the effect of shape of the sample, we have varied the aspect
+ratio $A^{}_r=L^{}_y/L^{}_x$ which in turn, is found to induce shape anisotropy
+in the system. Our main observations are: (a) When the dipolar interaction is
+strong $(\Theta>1)$, the ground state morphology has in-plane ordering of
+magnetic moments. (b) The ground state morphology has randomly oriented
+magnetic moments which is robust with respect to system sizes and $A^{}_r$ for
+weakly interacting MNPs ($\Theta<1$). (c) Micromagnetic simulations suggests
+that the dipolar interaction decreases the coercive field $H^{}_c$. (d) The
+remanence magnetization $M^{}_r$ is found to be strongly dependent not only on
+the strength of dipolar interaction but also on the shape of the sample. (e)
+Due to anisotropic nature of dipolar interaction, a strong effect of shape
+anisotropy is observed when the field is applied along longer axis of the
+sample. The dipolar interaction in such a case induces an effective
+ferromagnetic coupling when the aspect ratio is very large. These results are
+of vital importance in high-density recording systems, magneto-impedance
+sensors, etc.",2101.03356v1
+2021-01-15,Tunable spin-flop transition in artificial ferrimagnets,"Spin-flop transition (SFT) consists in a jump-like reversal of
+antiferromagnetic magnetic moments into a non-collinear state when the magnetic
+field increases above the critical value. Potentially the SFT can be utilized
+in many applications of a rapidly developing antiferromagnetic spintronics.
+However, the difficulty of using them in conventional antiferromagnets lies in
+(a) too large switching magnetic fields (b) the need for presence of a magnetic
+anisotropy, and (c) requirement to apply magnetic field along the correspondent
+anisotropy axis. In this work we propose to use artificial ferrimagnets in
+which the spin-flop transition occurs without anisotropy and the transition
+field can be lowered by adjusting exchange coupling in the structure. This is
+proved by experiment on artificial Fe-Gd ferrimagnets where usage of Pd spacers
+allowed us to suppress the transition field by two orders of magnitude.",2101.06155v2
+2021-01-17,Experimental determination of the magnetic interactions of frustrated Cairo pentagon lattice materials,"We present inelastic neutron scattering measurements of the Cairo pentagon
+lattice magnets Bi$_2$Fe$_4$O$_9$ and Bi$_4$Fe$_5$O$_{13}$F, supported by high
+field magnetisation measurements of Bi$_2$Fe$_4$O$_9$. Using linear spin wave
+theory and mean field analyses we determine the spin exchange interactions and
+single-ion anisotropy in these materials. The Cairo lattice is geometrically
+frustrated and consists of two inequivalent magnetic sites, both occupied by
+Fe$^{3+}$ ions and connected by two competing nearest neighbour interactions.
+We found that one of these interactions, coupling nearest neighbour spins on
+the three-fold symmetric sites, is extremely strong and antiferromagnetic.
+These strongly coupled dimers are then weakly coupled to a framework formed
+from spins occupying the other inequivalent site. In addition we found that the
+Fe$^{3+}$ $S=5/2$ spins have a non-negligible single-ion anisotropy, which
+manifests as a spin anisotropy gap in the neutron spectrum and a spin-flop
+transition in high field magnetisation measurements.",2101.06786v1
+2021-01-18,Giant Transport Anisotropy in ReS$_2$ Revealed via Nanoscale Conducting Path Control,"The low in-plane symmetry in layered 1T'-ReS$_2$ results in strong band
+anisotropy, while its manifestation in the electronic properties is challenging
+to resolve due to the lack of effective approaches for controlling the local
+current path. In this work, we reveal the giant transport anisotropy in
+monolayer to four-layer ReS$_2$ by creating directional conducting paths via
+nanoscale ferroelectric control. By reversing the polarization of a
+ferroelectric polymer top layer, we induce conductivity switching ratio of
+>1.5x10$^8$ in the ReS$_2$ channel at 300 K. Characterizing the domain-defined
+conducting nanowires in an insulating background shows that the conductivity
+ratio between the directions along and perpendicular to the Re-chain can exceed
+5.5x10$^4$. Theoretical modeling points to the band origin of the transport
+anomaly, and further reveals the emergence of a flat band in few-layer ReS$_2$.
+Our work paves the path for implementing the highly anisotropic 2D materials
+for designing novel collective phenomena and electron lensing applications.",2101.07379v2
+2021-02-15,Controlling Domain-Wall Nucleation in Ta/CoFeB/MgO Nanomagnets via Local Ga+ Ion Irradiation,"Comprehensive control of the domain wall nucleation process is crucial for
+spin-based emerging technologies ranging from random-access and storage-class
+memories over domain-wall logic concepts to nanomagnetic logic. In this work,
+focused Ga+ ion-irradiation is investigated as an effective means to control
+domain-wall nucleation in Ta/CoFeB/MgO nanostructures. We show that analogously
+to He+ irradiation, it is not only possible to reduce the perpendicular
+magnetic anisotropy but also to increase it significantly, enabling new,
+bidirectional manipulation schemes. First, the irradiation effects are assessed
+on film level, sketching an overview of the dose-dependent changes in the
+magnetic energy landscape. Subsequent time-domain nucleation characteristics of
+irradiated nanostructures reveal substantial increases in the anisotropy fields
+but surprisingly small effects on the measured energy barriers, indicating
+shrinking nucleation volumes. Spatial control of the domain wall nucleation
+point is achieved by employing focused irradiation of pre-irradiated magnets,
+with the diameter of the introduced circular defect controlling the coercivity.
+Special attention is given to the nucleation mechanisms, changing from a
+Stoner-Wohlfarth particle's coherent rotation to depinning from an anisotropy
+gradient. Dynamic micromagnetic simulations and related measurements are used
+in addition to model and analyze this depinning-dominated magnetization
+reversal.",2102.07540v1
+2021-02-17,Optimization of epitaxial graphene growth for quantum metrology,"(See the complete abstract within the thesis in both English and German
+versions)
+  In this thesis, the process conditions of the epitaxial graphene growth
+through a socalled polymer-assisted sublimation growth method are minutely
+investigated. Atomic force microscopy (AFM) is used to show that the previously
+neglected flow-rate of the argon process gas has a significant influence on the
+morphology of the SiC substrate and atop carbon layers. The results can be well
+explained using a simple model for the thermodynamic conditions at the layer
+adjacent to the surface. The resulting control option of step-bunching on the
+sub-nanometer scales is used to produce the ultra-flat, monolayer graphene
+layers without the bilayer inclusions that exhibit the vanishing of the
+resistance anisotropy. The comparison of four-point and scanning tunneling
+potentiometry measurements shows that the remaining small anisotropy represents
+the ultimate limit, which is given solely by the remaining resistances at the
+SiC terrace steps. ... The precise control of step-bunching using the Ar flow
+also enables the preparation of periodic non-identical SiC surfaces under the
+graphene layer. Based on the work function measurements by Kelvin-Probe force
+microscopy and X-ray photoemission electron microscopy, it is shown for the
+first time that there is a doping variation in graphene, induced by a proximity
+effect of the different near-surface SiC stacks. The comparison of the AFM and
+low-energy electron microscopy measurements have enabled the exact assignment
+of the SiC stacks, and the examinations have led to an improved understanding
+of the surface restructuring in the framework of a step-flow mode. ...",2102.08691v1
+2021-02-22,Spirals and skyrmions in antiferromagnetic triangular lattices,"We study realizations of spirals and skyrmions in two-dimensional
+antiferromagnets with a triangular lattice on an inversion-symmetry-breaking
+substrate. As a possible material realization, we investigate the adsorption of
+transition-metal atoms (Cr, Mn, Fe, or Co) on a monolayer of MoS$_2$, WS$_2$,
+or WSe$_2$ and obtain the exchange, anisotropy, and Dzyaloshinskii-Moriya
+interaction parameters using first-principles calculations. Using energy
+minimization and parallel-tempering Monte-Carlo simulations, we determine the
+magnetic phase diagrams for a wide range of interaction parameters. We find
+that skyrmion lattices can appear even with weak Dzyaloshinskii-Moriya
+interactions, but their stability is hindered by magnetic anisotropy. However,
+a weak easy plane magnetic anisotropy can be beneficial for stabilizing the
+skyrmion phase. Our results suggest that Cr$/$MoS$_2$, Fe$/$MoS$_2$, and
+Fe$/$WSe$_2$ interfaces can host spin spirals formed from the 120$^{\circ}$
+antiferromagnetic states. Our results further suggests that for other
+interfaces, such as Fe$/$MoS$_2$, the Dzyaloshinskii-Moriya interaction is
+strong enough to drive the system into a three-sublattice skyrmion lattice in
+the presence of experimentally feasible external magnetic field.",2102.11246v1
+2021-02-23,Phenomenological study of the anisotropic quark matter in the 2-flavor Nambu-Jona-Lasinio model,"With the two flavor Nambu-Jona-Lasinio (NJL) model we carry out a
+phenomenological study on the chiral phase structure, mesonic properties and
+transport properties in a momentum-space anisotropic quark matter. To calculate
+transport coefficients we have utilized the kinetic theory in the relaxation
+time approximation, where the momentum anisotropy is embedded in the estimation
+of both distribution function and the relaxation time. It is shown that an
+increase of the anisotropy parameter $\xi$ may results in a catalysis of chiral
+symmetry breaking. The critical endpoint (CEP) is shifted to smaller
+temperatures and larger quark chemical potentials as $\xi $ increases, the
+impact of momentum anisotropy on temperature of CEP is almost the same as that
+on the quark chemical potential of CEP. The meson masses and the associated
+decay widths also exhibit a significant $\xi$ dependence. It is observed that
+the temperature behavior of scaled shear viscosity $\eta/T^3$ and scaled
+electrical conductivity $\sigma_{el}/T$ exhibit a similar dip structure, with
+the minima of both $\eta/T^3$ and $\sigma_{el}/T$ shifting toward higher
+temperatures with increasing $\xi$. Furthermore, we demonstrate that the
+Seebeck coefficient $S$ decreases when temperature goes up and its sign is
+positive, indicating the dominant carriers for converting the temperature
+gradient to the electric field are up-quarks. The Seebeck coefficient $S$ is
+significantly enhanced with a large $\xi$ for the temperature below the
+critical temperature.",2102.11792v3
+2021-03-08,Anisotropic turbulent transport with horizontal shear in stellar radiative zones,"Context. Turbulent transport in stellar radiative zones is a key ingredient
+of stellar evolution theory, but the anisotropy of the transport due to the
+stable stratification and the rotation of these regions is poorly understood.
+The assumption of shellular rotation, which is a cornerstone of the so-called
+rotational mixing, relies on an efficient horizontal transport. However, this
+transport is included in many stellar evolution codes through phenomenological
+models that have never been tested.
+  Aims. We investigate the impact of horizontal shear on the anisotropy of
+turbulent transport.
+  Methods. We used a relaxation approximation (also known as {\tau}
+approximation) to describe the anisotropising effect of stratification,
+rotation, and shear on a background turbulent flow by computing velocity
+correlations.
+  Results. We obtain new theoretical scalings for velocity correlations that
+include the effect of horizontal shear. These scalings show an enhancement of
+turbulent motions, which would lead to a more efficient transport of chemicals
+and angular momentum, in better agreement with helio- and asteroseismic
+observations of rotation in the whole Hertzsprung-Russell diagram. Moreover, we
+propose a new choice for the non-linear time used in the relaxation
+approximation, which characterises the source of the turbulence.
+  Conclusions. For the first time, we describe the effect of stratification,
+rotation, and vertical and horizontal shear on the anisotropy of turbulent
+transport in stellar radiative zones. The new prescriptions need to be
+implemented in stellar evolution calculations. To do so, it may be necessary to
+implement non-diffusive transport.",2103.05473v1
+2021-03-17,Large Orbital Magnetic Moment and Strong Perpendicular Magnetic Anisotropy in Heavily Intercalated Fe$_{x}$TiS$_2$,"Titanium disulfide TiS$_2$, which is a member of the layered transition-metal
+dichalcogenides with the 1T-CdI$_2$-type crystal structure, is known to exhibit
+a wide variety of magnetism through intercalating various kinds of
+transition-metal atoms of different concentrations. Among them, Fe-intercalated
+titanium disulfide Fe$_x$TiS$_2$ is known to be ferromagnetic with strong
+perpendicular magnetic anisotropy (PMA) and large coercive fields
+($H_\text{c}$). In order to study the microscopic origin of the magnetism of
+this compound, we have performed X-ray absorption spectroscopy (XAS) and X-ray
+magnetic circular dichroism (XMCD) measurements on single crystals of heavily
+intercalated Fe$_x$TiS$_2$ ($x\sim0.5$). The grown single crystals showed a
+strong PMA with a large $H_\text{c}$ of $\mu_0H_\text{c} \simeq 1.0\ \text{T}$.
+XAS and XMCD spectra showed that Fe is fully in the valence states of 2+ and
+that Ti is in an itinerant electronic state, indicating electron transfer from
+the intercalated Fe atoms to the host TiS$_2$ bands. The Fe$^{2+}$ ions were
+shown to have a large orbital magnetic moment of $\simeq 0.59\
+\mu_\text{B}\text{/Fe}$, to which, combined with the spin-orbit interaction and
+the trigonal crystal field, we attribute the strong magnetic anisotropy of
+Fe$_x$TiS$_2$.",2103.09538v2
+2021-03-30,Positive magnetoresistance and chiral anomaly in exfoliated type-II Weyl semimetal $T_\mathrm{d}$-WTe$_{2}$,"Layered van der Waals semimetallic $T_\mathrm{d}$-WTe$_{2}$, exhibiting
+intriguing properties which include non-saturating extreme positive
+magnetoresistance (MR) and tunable chiral anomaly, has emerged as model
+topological type-II Weyl semimetal system. Here, $\sim$45 nm thick mechanically
+exfoliated flakes of $T_\mathrm{d}$-WTe$_{2}$ are studied $via$ atomic force
+microscopy, Raman spectroscopy, low-$T$/high-$\mu_{0}H$ magnetotransport
+measurements and optical reflectivity. The contribution of anisotropy of the
+Fermi liquid state to the origin of the large positive transverse
+$\mathrm{MR}_\perp$ and the signature of chiral anomaly of the type-II Weyl
+fermions are reported. The samples are found to be stable in air and no
+oxidation or degradation of the electronic properties are observed. A
+transverse $\mathrm{MR}_\perp$ $\sim$1200\,\% and an average carrier mobility
+of $5000$\, cm$^{2}$V$^{-1}$s$^{-1}$ at $T=5\,\mathrm{K}$ for an applied
+perpendicular field $\mu_{0}H_{\perp} = 7\,\mathrm{T}$ are established. The
+system follows a Fermi liquid model for $T\leq50\,\mathrm{K}$ and the
+anisotropy of the Fermi surface is concluded to be at the origin of the
+observed positive MR. The anisotropy of the electronic behaviour is also
+confirmed by optical reflectivity measurements. The relative orientation of the
+crystal axes and of the applied electric and magnetic fields is proven to give
+rise to the observed chiral anomaly in the in-plane magnetotransport.",2103.16326v1
+2021-04-10,Thermal buckling of thin injection-molded FRP plates with fiber orientation varying over the thickness,"The different thermo-elastic properties of glass fibers and polymer matrices
+can generate residual thermal stresses in injection-molded fiber-reinforced
+plastic (FRP) objects. During cooling from mold to room temperature, these
+stresses can be relaxed by large deformations resulting from an instability of
+the unwarped configuration (i.e., buckling). This article investigates the
+thermal buckling of thin FRP disks via an analytical formulation based on the
+Foppl-von Karman theory. Expanding on our previous work, cylindrical orthotropy
+with material parameters varying over the disk thickness is assumed in order to
+account for thickness dependency of the glass fiber orientation distribution. A
+disk parameter generalizing the thermal anisotropy ratio for homogeneous
+orthotropic disks is introduced and its relation with the occurrence and
+periodicity of buckling is discussed. This is done for a skin-coreskin model,
+for which the core-to-total thickness ratio is defined. For fiber orientation
+distributions typical of injection-molded disks, it is found that there exists
+a value of the thickness ratio for which no buckling occurs. It is also
+demonstrated that the periodicity of the first buckling mode is described by
+the generalized thermal anisotropy ratio, thus extending the results obtained
+for a homogeneous fiber orientation distribution. Improvements in the accuracy
+of the predictions for experimental data available in the literature when using
+the skin-core-skin model are shown. Finally, we study the relation between
+buckling temperature and disk thickness and propose an expression for the
+dependence of the normalized buckling temperature on the thermal anisotropy
+ratio. Results of FEM simulations are used to validate the proposed expression,
+proving its applicability and accuracy.",2104.04735v1
+2021-04-25,Topological quantum phase transition in the magnetic semimetal HoSb,"Magnetic topological semimetals, a novel state of quantum matter with
+nontrivial band topology, have emerged as a new frontier in physics and
+materials science. An external stimulus like temperature or magnetic field
+could be expected to alter their spin states and thus the Fermi surface
+anisotropies and topological features. Here, we perform the angular
+magnetoresistance measurements and electronic band structure calculations to
+reveal the evolution of HoSb's Fermi surface anisotropies and topological
+nature in different magnetic states. The angular magnetoresistance results
+manifest that its Fermi surface anisotropy is robust in the paramagnetic state
+but is significantly modulated in the antiferromagnetic and ferromagnetic
+states. More interestingly, a transition from the trivial (nontrivial) to
+nontrivial (trivial) topological electronic phase is observed when HoSb
+undergoes a magnetic transition from the paramagnetic (antiferromagnetic) to
+antiferromagnetic (ferromagnetic) state induced by temperature (applied
+magnetic field). Our studying suggests that HoSb provides an archetype platform
+to study the correlations between magnetism and topological states of matter.",2104.12054v1
+2021-05-06,Quantum Oscillation of Thermally Activated Conductivity in a Monolayer WTe$_2$-like Excitonic Insulator,"Recently, quantum oscillation of the resistance in insulating monolayer
+WTe$_2$ was reported. An explanation in terms of gap modulation in the
+hybridized Landau levels of an excitonic insulator was also proposed by one of
+us. However, the previous picture of gap modulation in the Landau levels
+spectrum was built on a pair of well nested electron and hole Fermi surfaces,
+while the monolayer WTe$_2$ has one hole and two electron Fermi pockets with
+relative anisotropy. Here we demonstrate that for system like monolayer
+WTe$_2$, the excitonic insulating state arising from the coupled one hole and
+two electron pockets possesses a finite region in interaction parameter space
+that shows gap modulation in a magnetic field. In this region, the thermally
+activated conductivity displays the $1/B$ periodic oscillation and it can
+further develop into discrete peaks at low temperature, in agreement with the
+experimental observation. We show that the relative anisotropy of the bands is
+a key parameter and the qunatum oscillations decrease rapidly if the anisotropy
+increases further than the realistic value for monolayer WTe$_2$.",2105.02411v2
+2021-05-13,Effect of magnetic anisotropy relaxation on laser-induced magnetization precession in thin galfenol films,"The rate and pathways of relaxation of a magnetic medium to its equilibrium
+following excitation with intense and short laser pulses are the key
+ingredients of ultrafast optical control of spins. Here we study experimentally
+the evolution of the magnetization and magnetic anisotropy of thin films of a
+ferromagnetic metal galfenol (Fe$_{0.81}$Ga$_{0.19}$) resulting from excitation
+with a femtosecond laser pulse. From the temporal evolution of the hysteresis
+loops we deduce that the magnetization $M_S$ and magnetic anisotropy parameters
+$K$ recover within a nanosecond, and the ratio between $K$ and $M_S$ satisfies
+the thermal equilibrium's power law in the whole time range spanning from a few
+picoseconds to 3 nanoseconds. We further use the experimentally obtained
+relaxation times of $M_S$ and $K$ to analyze the laser-induced precession and
+demonstrate how they contribute to its frequency evolution at the nanosecond
+timescale.",2105.06385v4
+2021-05-15,ElATools: A tool for analyzing anisotropic elastic properties of the 2D and 3D materials,"We introduce a computational method and a user-friendly code with a
+terminal-based graphical user interface (GUI), named ElATools, developed to
+analyze mechanical and anisotropic elastic properties. ElATools enables facile
+analysis of the second-order elastic stiffness tensor of two-dimensional (2D)
+and three-dimensional (3D) crystal systems. It computes and displays the main
+mechanical properties including the bulk modulus, Young's modulus, shear
+modulus, hardness, p-wave modulus, universal anisotropy index, Chung-Buessem
+anisotropy index, log-Euclidean anisotropy parameter, Cauchy pressures,
+Poisson's ratio, and Pugh's ratio, using three averaging schemes of Voigt,
+Reuss, and Hill. It includes an online and offline database from the Materials
+Project with more than 13,000 elastic stiffness constants for 3D materials. The
+program supports output files of the well-known computational codes IRelast,
+IRelast2D, ElaStic, and AELAS. Four types of plotting and visualization tools
+are integrated to conveniently interface with GNUPLOT, XMGRACE, view3dscene,
+and plotly libraries, offering immediate post-processing of the results. It can
+efficiently identify anomalous mechanical properties, such as negative linear
+compressibility, negative Poisson's ratio, and highly-anisotropic elastic
+modulus in 2D and 3D materials, which are central properties to design and
+develop high-performance nanoscale electromechanical devices. Six case studies
+on selected material systems, namely, ZnAu$_2$ (CN)$_4$, CrB$_2$,
+$\delta$-phosphorene, Pd$_2$O$_6$Se$_2$ monolayer, and GaAs, and a hypothetical
+set of systems with cubic symmetry are presented to demonstrate the descriptive
+and predictive capabilities of ElATools.",2105.07279v3
+2021-05-20,Restoring isotropy in a three-dimensional lattice model: The Ising universality class,"We study a generalized Blume-Capel model on the simple cubic lattice. In
+addition to the nearest neighbor coupling there is a next to next to nearest
+neighbor coupling. In order to quantify spatial anisotropy, we determine the
+correlation length in the high temperature phase of the model for three
+different directions. It turns out that the spatial anisotropy depends very
+little on the dilution parameter $D$ of the model and is essentially determined
+by the ratio of the nearest neighbor and the next to next to nearest neighbor
+coupling. This ratio is tuned such that the leading contribution to the spatial
+anisotropy is eliminated. Next we perform a finite size scaling (FSS) study to
+tune $D$ such that also the leading correction to scaling is eliminated. Based
+on this FSS study, we determine the critical exponents $\nu=0.62998(5)$ and
+$\eta=0.036284(40)$, which are in nice agreement with the more accurate results
+obtained by using the conformal bootstrap method. Furthermore we provide
+accurate results for fixed point values of dimensionless quantities such as the
+Binder cumulant and for the critical couplings. These results provide the
+groundwork for broader studies of universal properties of the three-dimensional
+Ising universality class.",2105.09781v2
+2021-05-27,Delineating corneal elastic anisotropy in a porcine model using non-contact optical coherence elastography and ex vivo mechanical tests,"Objective: To compare non-contact acoustic micro-tapping optical coherence
+elastography (AuT-OCE) with destructive mechanical tests to confirm corneal
+elastic anisotropy.
+  Design: Ex vivo, laboratory study with non-contact AuT-OCE followed by
+mechanical rheometry and extensometry.
+  Subjects: Inflated cornea of whole-globe porcine eyes.
+  Methods: A non-contact transducer was used to launch mechanical waves in the
+cornea that were imaged with phase-sensitive OCT at physiologically relevant
+pressures. Reconstruction of both Young's modulus (E) and out-of-plane shear
+modulus (G) in the cornea from experimental data was performed using a model of
+a nearly incompressible transversally isotropic (NITI) medium. Samples were
+then excised and parallel plate rheometry was performed to measure the shear
+modulus G. Corneal samples were then subjected to strip extensomety to measure
+the Young's modulus.
+  Main Outcome Measures: Strong corneal anisotropy was confirmed with both
+AuT-OCE and mechanical tests, with the Young's and shear moduli differing by
+over an order of magnitude. These results show that AuT-OCE can quantify both
+moduli with a non-contact, non-invasive, clinically translatable technique.",2105.13140v1
+2021-06-04,Optical read-out of the Néel vector in metallic antiferromagnet Mn$_{2}$Au,"Metallic antiferromagnets with broken inversion symmetry on the two
+sublattices, strong spin-orbit coupling and high N\'{e}el temperatures offer
+new opportunities for applications in spintronics. Especially Mn$_{2}$Au, with
+high N\'{e}el temperature and conductivity, is particularly interesting for
+real-world applications. Here, manipulation of the orientation of the staggered
+magnetization,\textit{\ i.e.} the N\'{e}el vector, by current pulses has been
+recently demonstrated, with the read-out limited to studies of anisotropic
+magnetoresistance or X-ray magnetic linear dichroism. Here, we report on the
+in-plane reflectivity anisotropy of Mn$_{2}$Au (001) films, which were N\'{e}el
+vector aligned in pulsed magnetic fields. In the near-infrared, the anisotropy
+is $\approx$ 0.6\%, with higher reflectivity for the light polarized along the
+N\'{e}el vector. The observed magnetic linear dichroism is about four times
+larger than the anisotropic magnetoresistance. This suggests the dichroism in
+Mn$_{2}$Au is a result of the strong spin-orbit interactions giving rise to
+anisotropy of interband optical transitions, in-line with recent studies of
+electronic band-structure. The considerable magnetic linear dichroism in the
+near-infrared could be used for ultrafast optical read-out of the N\'{e}el
+vector in Mn$_{2}$Au.",2106.02729v2
+2021-06-27,A new low-beta regime for unstable proton firehose modes in bi-Kappa distributed plasmas,"In the solar wind plasma an excess of kinetic temperature along the
+background magnetic field stimulates proton firehose modes to grow if the
+parallel plasma beta parameter is sufficiently high, i.e., $\beta_{p
+\parallel}\gtrsim 1$. This instability can prevent the expansion-driven
+anisotropy from increasing indefinitely, and explain the observations.
+Moreover, such kinetic instabilities are expected to be even more effective in
+the presence of suprathermal Kappa-distributed populations, which are
+ubiquitous in the solar wind, are less affected by collisions than the core
+population, but contribute with an additional free energy. In this work we use
+both linear and extended quasi-linear (QL) frameworks to characterize the
+unstable periodic proton firehose modes (propagating parallel to the magnetic
+field) under the influence of suprathermal protons. Linear theory predicts a
+systematic stimulation of the instability, suprathermals amplifying the growth
+rates and decreasing the instability thresholds to lower anisotropies and lower
+plasma betas ($\beta_{p \parallel}<1$). In perfect agreement with these
+results, the QL approach reveals a significant enhancement of the resulting
+electromagnetic fluctuations up to the saturation with a stronger back reaction
+on protons, leading also to a faster and more efficient relaxation of the
+temperature anisotropy.",2106.14291v1
+2021-07-06,Relativistic aspects of orbital and magnetic anisotropies in the chemical bonding and structure of lanthanide molecules,"The electronic structure of magnetic lanthanide atoms is fascinating from a
+fundamental perspective. They have electrons in a submerged open 4f shell lying
+beneath a filled 6s shell with strong relativistic correlations leading to a
+large magnetic moment and large electronic orbital angular momentum. This large
+angular momentum leads to strong anisotropies, i. e. orientation dependencies,
+in their mutual interactions. The long-ranged molecular anisotropies are
+crucial for proposals to use ultracold lanthanide atoms in spin-based quantum
+computers, the realization of exotic states in correlated matter, and the
+simulation of orbitronics found in magnetic technologies. Short-ranged
+interactions and bond formation among these atomic species have thus far not
+been well characterized. Efficient relativistic computations are required.
+Here, for the first time we theoretically determine the electronic and
+ro-vibrational states of heavy homonuclear lanthanide Er2 and Tm2 molecules by
+applying state-of-the-art relativistic methods. In spite of the complexity of
+their internal structure, we were able to obtain reliable spin-orbit and
+correlation-induced splittings between the 91 Er2 and 36 Tm2 electronic
+potentials dissociating to two ground-state atoms. A tensor analysis allows us
+to expand the potentials between the atoms in terms of a sum of seven spin-spin
+tensor operators simplifying future research. The strengths of the tensor
+operators as functions of atom separation are presented and relationships among
+the strengths, derived from the dispersive long-range interactions, are
+explained. Finally, low-lying spectroscopically relevant ro-vibrational energy
+levels are computed with coupled-channels calculations and analyzed.",2107.02676v1
+2021-07-08,"Unconventional thermal and magnetic-field-driven changes of a bipartite entanglement of a mixed spin-(1/2,$S$) Heisenberg dimer with an uniaxial single-ion anisotropy","The concept of negativity is adapted in order to explore the quantum and
+thermal entanglement of the mixed spin-(1/2,$S$) Heisenberg dimers in presence
+of an external magnetic field. The mutual interplay between the spin size $S$,
+XXZ exchange and uniaxial single-ion anisotropy is thoroughly examined with a
+goal to tune the degree and thermal stability of the pairwise entanglement. It
+turns out that the antiferromagnetic spin-(1/2,$S$) Heisenberg dimers exhibit
+higher degree of entanglement and higher threshold temperature in comparison
+with their ferromagnetic counterparts when assuming the same set of model
+parameters. The increasing spin magnitude $S$ accompanied with an easy-plane
+uniaxial single-ion anisotropy can enhance not only the thermal stability but
+simultaneously the degree of entanglement. It is additionally shown that the
+further enhancement of a bipartite entanglement can be achieved in the mixed
+spin-(1/2,$S$) Heisenberg dimers, involving half-odd-integer spins $S$. Under
+this condition the thermal negativity saturates at low-enough temperatures in
+its maximal value regardless of the magnitude of half-odd-integer spin $S$. The
+magnetic field induces consecutive discontinuous phase transitions in the mixed
+spin-(1/2,$S$) Heisenberg dimers with $S\!>\!1$, which are manifested in a
+surprising oscillating magnetic-field dependence of the negativity observed at
+low enough temperature.",2107.05628v2
+2021-07-19,MoP$_3$SiO$_{11}$: a $4d^3$ honeycomb antiferromagnet with disconnected octahedra,"We report the crystal structure and magnetic behavior of the $4d^3$
+spin-$\frac32$ silicophosphate MoP$_3$SiO$_{11}$ studied by high-resolution
+synchrotron x-ray diffraction, neutron diffraction, thermodynamic measurements,
+and ab initio band-structure calculations. Our data revise the crystallographic
+symmetry of this compound and establish its rhombohedral space group ($R\bar
+3c$) along with the geometrically perfect honeycomb lattice of the Mo$^{3+}$
+ions residing in disconnected MoO$_6$ octahedra. Long-range antiferromagnetic
+order with the propagation vector $\mathbf k=0$ observed below $T_N=6.8$ K is a
+combined effect of the nearest-neighbor in-plane exchange coupling $J\simeq
+2.6$ K, easy-plane single-ion anisotropy $D\simeq 2.2 $ K, and a weak
+interlayer coupling $J_c\simeq 0.8$ K. The 12% reduction in the ordered
+magnetic moment of the Mo$^{3+}$ ions and the magnon gap of $\Delta\simeq 7$ K
+induced by the single-ion anisotropy further illustrate the impact of
+spin-orbit coupling on the magnetism. Our analysis puts forward single-ion
+anisotropy as an important ingredient of $4d^3$ honeycomb antiferromagnets
+despite their nominally quenched orbital moment.",2107.08618v2
+2021-07-23,Intermixing Induced Anisotropy Variations in CoB-based Chiral Multilayer Films,"We examine the atomic intermixing phenomenon in three distinct amorphous
+CoB-based multilayer thin film platforms - Pt/CoB/Ir, Ir/CoB/Pt and Pt/CoB/MgO
+- which are shown to stabilise room-temperature chiral magnetic textures.
+Intermixing occurs predominantly between adjacent metallic layers. Notably, it
+is stack-order dependent, and particularly extensive when Ir sits atop CoB.
+Intermixing induced variations in magnetic properties are ascribed to the
+formation of magnetic dead layer arising from CoIr alloying in the metallic
+stacks. It also produces systematic variations in saturation magnetization, by
+as much as 30%, across stacks. Crucially, the resulting crossover CoB thickness
+for the transition from perpendicular to in-plane magnetic anisotropy differs
+by more than 2x across the stacks. Finally, with thermal annealing treatment
+over moderate temperatures of 150-300 degree Celsius, the magnetic anisotropy
+increases monotonically across all stacks, coupled with discernibly larger Hc
+for the metallic stacks. These are attributed to thermally induced CoPt
+alloying and MgO crystallization in the metallic and oxide stacks,
+respectively. Remarkably, the CoB in the Pt/CoB/MgO stacks retains its
+amorphous nature after annealing. Our results set the stage for harnessing the
+collective attributes of amorphous CoB-based material platforms and associated
+annealing processes for modulating magnetic interactions, enabling the tuning
+of chiral magnetic texture properties in ambient conditions.",2107.11034v1
+2021-07-23,Observation of Cosmic Ray Anisotropy with Nine Years of IceCube Data,"The IceCube Observatory has collected over 577 billion cosmic-ray induced
+muon events in its final configuration from May 2011 to May 2020. We used this
+data set to provide an unprecedented statistically accurate map of the cosmic
+ray arrival direction distribution in the TeV-PeV energy range scale in the
+Southern Hemisphere. Such an increase in event statistics makes it possible to
+extend the sensitivity to anisotropies at higher cosmic ray energies and
+smaller angular scales. It will also facilitate a more detailed assessment of
+the observatory stability over both short- and long-time scales. This will
+enable us to study the time variability of the cosmic ray anisotropy on a
+yearly-base and over the entire data sample period covering most of the solar
+cycle 24. We present the preliminary results from the study with the extended
+event sample.",2107.11454v1
+2021-08-03,"Adaptive critical balance and firehose instability in an expanding, turbulent, collisionless plasma","Using hybrid-kinetic particle-in-cell simulation, we study the evolution of
+an expanding, collisionless, magnetized plasma in which strong Alfv\'enic
+turbulence is persistently driven. Temperature anisotropy generated
+adiabatically by the plasma expansion (and consequent decrease in the mean
+magnetic-field strength) gradually reduces the effective elasticity of the
+field lines, causing reductions in the linear frequency and residual energy of
+the Alfv\'{e}nic fluctuations. In response, these fluctuations modify their
+interactions and spatial anisotropy to maintain a scale-by-scale ""critical
+balance"" between their characteristic linear and nonlinear frequencies.
+Eventually the plasma becomes unstable to kinetic firehose instabilities, which
+excite rapidly growing magnetic fluctuations at ion-Larmor scales. The
+consequent pitch-angle scattering of particles maintains the temperature
+anisotropy near marginal stability, even as the turbulent plasma continues to
+expand. The resulting evolution of parallel and perpendicular temperatures does
+not satisfy double-adiabatic conservation laws, but is described accurately by
+a simple model that includes anomalous scattering. Our results have
+implications for understanding the complex interplay between macro- and
+micro-scale physics in various hot, dilute, astrophysical plasmas, and offer
+predictions concerning power spectra, residual energy, ion-Larmor-scale
+spectral breaks, and non-Maxwellian features in ion distribution functions that
+may be tested by measurements taken in high-beta regions of the solar wind.",2108.01491v2
+2021-08-04,Anisotropic turbulence in relativistic plasmas,"Signs of turbulence have been observed at the relativistic heavy ion
+collision at high collision energies. We study the signatures of turbulence in
+this system and find that there are significant departures from isotropic
+turbulence in the initial stages of the collision. Since the anisotropic
+fluctuations are sub leading to the isotropic fluctuations, the Kolmogorov
+spectrum can usually be obtained even for the initial stages. However, the
+energy spectrum and the temperature fluctuations indicate deviations from
+isotropic turbulence. Since a strong momentum anisotropy exists between the
+transverse and the longitudinal plane, we study the energy density spectrum in
+these two planes. The geometrical anisotropy is reflected in the anisotropic
+turbulence generated in the rotating plasma and we find that the scaling
+exponent is different in the two planes. We find that the scaling exponents in
+the longitudinal plane are independent of centrality while the scaling exponent
+in the transverse plane depends on the centrality range. We also obtain the
+temperature spectrum in the initial stages. The spectrum deviates from the
+Gaussian spectra expected for an isotropic turbulence. All these seem to
+indicate that the large scale momentum anisotropy persists in the smaller
+length scales for the relativistic heavy ion collisions.",2108.01847v2
+2021-08-10,Composition Sensitivity (for the Cosmic Ray Anisotropy with SWGO),"A number of cosmic-ray observatories have measured a change in both phase and
+amplitude of the dipole component in the distribution of cosmic-ray arrival
+directions above a primary energy of 100 TeV. We focus on probing the
+cosmic-ray dipole and multipole evolution in the energy region of mutli TeV to
+beyond PeV with a future large-area gamma-ray observatory, such as the Southern
+Wide-field Gamma-ray Observatory (SWGO). The ability to discriminate between
+different mass groups is essential to understand the origin of this evolution.
+Through a consideration of the energy and mass resolution for cosmic-ray
+detection by such an observatory, we estimate its separation power for
+decomposing the full-particle anisotropy into mass groups. In particular, we
+explore the feasibility of probing the dipole evolution with rigidity with
+SWGO. In this way, we demonstrate the great potential that this instrument
+offers for providing a deeper understanding of the origin of the cosmic-ray
+anisotropy.",2108.04609v1
+2021-08-10,The orbital effect on the anomalous magnetism and evolution in La$_x$Y$_{1-x}$VO$_3$($0\le x \le 0.2$) single crystals,"The orbital effect on the anomalous magnetism and evolution of low La-doping
+single crystals, La$_x$Y$_{1-x}$VO$_{3}$ (x = 0, 0.1, and 0.2), has been
+investigated by applying the X-ray diffraction, specific heat, magnetization
+and Raman scattering techniques. The larger nearest-neighbor (NN) exchange
+interaction along c-axis stabilizes the fluctuant G-type orbital ordering
+(G-OO) which favors the exotic C-type antiferromagnetic order (C-AF). It is
+found that the NN exchange interaction in ab plane is anisotropy relating to
+the in plane magnetic anisotropy, which becomes smaller in high La-doped
+sample. Most interestingly, with increasing the La$^{3+}$ content the orbital
+fluctuation and hybridization are decreased which stabilizes the C-OO phase and
+destabilizes the G-OO phase. Meanwhile, the diamagnetism in the exotic C-AF
+phase becomes weak and the possible mechanism relates to the change of the
+competition between the single-ion magnetic anisotropy and the
+Dzyaloshinsky-Moriya (DM) interaction with increasing x. Finally, the strong
+spin-orbital coupling has been observed at temperature just above T$_N$ in
+La$_{0.2}$Y$_{0.8}$VO$_{3}$ and a short range spin-orbital correlation is
+suggested.",2108.04648v1
+2021-08-17,Probing small-scale baryon and dark matter isocurvature perturbations with cosmic microwave background anisotropies,"The Universe's initial conditions, in particular baryon and cold dark matter
+(CDM) isocurvature perturbations, are poorly constrained on sub-Mpc scales. In
+this paper, we develop a new formalism to compute the effect of small-scale
+baryon perturbations on the mean free-electron abundance, thus on cosmic
+microwave background (CMB) anisotropies. Our framework can accommodate
+perturbations with arbitrary time and scale dependence. We apply this formalism
+to four different combinations of baryon and CDM isocurvature modes, and use
+Planck CMB-anisotropy data to probe their initial amplitude. We find that
+Planck data is consistent with no small-scale isocurvature perturbations, and
+that this additional ingredient does not help alleviate the Hubble tension. We
+set upper bounds to the dimensionless initial power spectrum
+$\Delta_{\mathcal{I}}^2(k)$ of these isocurvature modes at comoving wavenumbers
+$1~\textrm{Mpc}^{-1} \le k \le 10^3$ Mpc$^{-1}$, for several parameterizations.
+For a scale-invariant power spectrum, our 95% confidence-level limits on
+$\Delta_{\mathcal{I}}^2$ are 0.023 for pure baryon isocurvature, 0.099 for pure
+CDM isocurvature, 0.026 for compensated baryon-CDM perturbations, and 0.009 for
+joint baryon-CDM isocurvature perturbations. Using a Fisher analysis
+generalized to non-analytic parameter dependence, we forecast that a CMB
+Stage-4 experiment would be able to probe small-scale isocurvature
+perturbations with initial power 3 to 10 times smaller than Planck limits. The
+formalism introduced in this work is very general and can be used more widely
+to probe any physical processes or initial conditions sourcing small-scale
+baryon perturbations.",2108.07798v1
+2021-08-24,Direct Calculation of the Eddy Viscosity Operator in Turbulent Channel Flow at Re$_τ$=180,"This study aims to quantify how turbulence in a channel flow mixes momentum
+in the mean sense. We applied the macroscopic forcing method (Mani and Park,
+Physical Review Fluids, 2021, p.054607) to direct numerical simulation (DNS) of
+a turbulent channel flow at Re_tau=180 using two different forcing strategies
+that are designed to separately assess the anisotropy and nonlocality of
+momentum mixing. In the first strategy, the leading term of the Kramers-Moyal
+expansion of the eddy viscosity is quantified, revealing all 81 tensorial
+coefficients that essentially characterize the local-limit eddy viscosity. The
+results indicate: (1) the eddy viscosity has significant anisotropy, (2)
+Reynolds stresses are generated by both the mean strain rate and mean rotation
+rate tensors associated with the momentum field, and (3) the local-limit eddy
+viscosity generates asymmetric Reynolds stress tensors. In the second strategy,
+the eddy viscosity is quantified as an integration kernel revealing the
+nonlocal influence of the mean momentum gradient at each wall-normal coordinate
+on all nine components of the Reynolds stresses over the channel width. Our
+results indicate that while the shear component of the Reynolds stress is
+reasonably controlled by the local mean gradients, other components of the
+Reynolds stress are highly nonlocal. These results provide an understanding of
+anisotropy and nonlocality requirements for closure modeling of momentum
+transport in wall-bounded turbulent flows.",2108.10898v3
+2021-08-31,Using in-plane anisotropy to engineer Janus monolayers of rhenium dichalcogenides,"The new class of Janus two-dimensional (2D) transition-metal dichalcogenides
+with two different interfaces are currently gaining increasing attention due to
+their distinct properties different from the typical 2D materials. Here, we
+show that in-plane anisotropy of a 2D atomic crystal, like ReS$_{2}$ or
+ReSe$_{2}$, allows formation of a large number of inequivalent Janus
+monolayers. We use first-principles calculations to investigate the structural
+stability of 29 distinct ReX$_{2-x}$Y$_{x}$ ($\mathrm{X,Y \in \{S,Se\}}$)
+structures, which can be obtained by selective exchange of exposed chalcogens
+in a ReX$_{2}$ monolayer. We also examine the electronic properties and work
+function of the most stable Janus monolayers and show that the large number of
+inequivalent structures provides a way to engineer spin-orbit splitting of the
+electronic bands. We find that the breaking of inversion symmetry leads to
+sizable spin splittings and spontaneous diople moments than are larger than
+those in other Janus dichalcogenides. Moreover, our caluclations suggest that
+the work function of the Janus monolayers can be tuned by varying the content
+of the substituting chalcogen. Our work demonstrates that in-plane anisotropy
+provides additional flexibility in sub-layer engineering of 2D atomic crystals.",2109.00071v2
+2021-09-02,Spin-$S$ impurities with XXZ anisotropy in a spin-1/2 Heisenberg chain,"We study the effect of anisotropy of spin-$S$ impurities on an
+antiferromagnetic SU(2) Heisenberg chain. The magnetic impurities are assumed
+to have an XXZ-type anisotropic exchange with its neighboring sites. First,
+using density-matrix renormalization group technique. we examine spin-spin
+correlation function, instability of N\'eel order, and local spin
+susceptibility in the presence of a single spin-$S$ impurity. Based on the
+results, we find that the types of spin-$S$ impurities are classified into two
+groups: $\rm(\hspace{.18em}i\hspace{.18em})$ nonmagnetic and $S=1$ impurities
+enhance only short-range antiferromagnetic correlation and
+$\rm(\hspace{.08em}ii\hspace{.08em})$ $S=1/2$ and $S>1$ impurities can, in
+contrast, stabilize a long-range N\'eel order in the disordered SU(2)
+Heisenberg chain. Then, we focus on the case of $S=1/2$ impurity as a
+representative of $\rm(\hspace{.08em}ii\hspace{.08em})$ and investigate the
+evolution of some experimentally observable quantities such as magnetization,
+specific heat, and magnetic susceptibility, as a function of concentration and
+XXZ anisotropy strength of the impurity. We confirm that the N\'eel order is
+induced in the bulk spin chain in the presence of finite amount of easy-axis
+XXZ $S=1/2$ impurities. Furthermore, we recover some of the aforementioned
+features using cluster mean-field theory, which allows us to present results on
+experimentally accessible quantities at finite temperatures. Interestingly, in
+the presence of uniform magnetic field, the total magnetization exhibits a
+pseudo-gap behavior for low values of applied field. We also discuss the
+dependence of NMR spectrum on various XXZ impurities and identify that the spin
+state of Co impurity in SrCu$_{0.99}$Co$_{0.01}$O$_2$ is $S = 3/2$.",2109.00777v1
+2021-09-05,Cooperative control of perpendicular magnetic anisotropy via crystal structure and orientation in single-crystal flexible SrRuO3 membranes,"Flexible magnetic materials with robust and controllable perpendicular
+magnetic anisotropy (PMA) are highly desirable for developing flexible
+high-performance spintronic devices. However, it is still challenge to
+fabricate PMA films through current techniques of direct deposition on
+polymers. Here, we report a facile method for synthesizing single-crystal
+freestanding SrRuO3 (SRO) membranes with controlled crystal structure and
+orientation using water-soluble Ca3-xSrxAl2O6 sacrificial layers. Through
+cooperative effect of crystal structure and orientation engineering, flexible
+SrRuO3 membranes reveal highly tunable magnetic anisotropy from in-plane to
+our-of-plane with a remarkable PMA energy of 7.34*106 erg/cm3. Based on the
+first-principles calculations, it reveals that the underlying mechanism of PMA
+modulation is intimately correlated with structure-controlled Ru 4d-orbital
+occupation, as well as the spin-orbital matrix element differences, dependent
+on the crystal orientation. In addition, there are no obvious changes of the
+magnetism after 10,000 bending cycles, indicating an excellent magnetism
+reliability in the prepared films. This work provides a feasible approach to
+prepare the flexible oxide films with strong and controllable PMA.",2109.02061v1
+2021-09-16,Influence of Heliolatitudinal Anisotropy of Solar FUV/EUV Emissions on Lyman-alpha Helioglow: SOHO/SWAN Observations and WawHelioGlow Modeling,"Observations of the Sun's surface suggest a nonuniform radiated flux as
+related to the presence of bright active regions and darker coronal holes. The
+variations of the FUV/EUV source radiation can be expected to affect the
+Lyman-alpha backscatter glow measured by spaceborne instruments. In particular,
+inferring the heliolatitudinal structure of the solar wind from helioglow
+variations in the sky can be quite challenging if the heliolatitudinal
+structure of the solar FUV/EUV radiation is not properly included in the
+modeling of the heliospheric glow. We present results of analysis of the
+heliolatitudinal structure of the solar Lyman-alpha radiation as inferred from
+comparison of SOHO/SWAN satellite observations of the helioglow intensity with
+modeling results obtained from the recently-developed WawHelioGlow model. We
+find that in addition to time-dependent heliolatitudinal anisotropy of the
+solar wind, also time-dependent heliolatitudinal variations of the intensity of
+the solar Lyman-alpha and photoionizing emissions must be taken into account to
+reproduce the observed helioglow modulation in the sky. We present a particular
+latitudinal and temporal dependence of the solar Lyman-alpha flux obtained as a
+result of our analysis. We analyze also differences between polar-equatorial
+anisotropies close to the solar surface and seen by an observer located far
+from the Sun. We discuss the implications of these findings for the
+interpretation of heliospheric-glow observations.",2109.08095v1
+2021-10-06,Exploring the possible origin of spin reorientation transition in NdCrO$_3$,"Spin reorientation transitions and other related magnetic phenomena, which
+owe their origin to the complex interplay between multiple magnetic
+sublattices, have long attracted scientific attention both from the perspective
+of fundamental curiosity and technological applications. In this study,
+combining first principles calculations together with finite temperature Monte
+Carlo simulations, we explore the possible origins of reorientation transition
+of Cr spins in NdCrO$_3$. We construct a NdCrO$_3$ specific magnetic model,
+consisting of symmetric superexchange interactions between magnetic ions, as
+well as their magnetic anisotropy. We show that the observed spin reorientation
+in NdCrO$_3$, arises out of a delicate balance between Nd$-$Cr magnetic
+exchange interactions, single ion anisotropy of Nd spins, and single ion
+anisotropy of Cr spins. Moreover, though our model does not take into
+consideration the effect of anti-symmetric and anisotropic-symmetric magnetic
+exchanges, the qualitative as well as quantitative agreement of the
+theoretically derived and the experimentally observed spin-reorientation
+transition in NdCrO$_3$, confirms the merit of our proposed microscopic model.
+Our results also propose a hitherto unobserved collective magnetic ordering in
+Nd sublattice, which is challenging to detect as it is an extreme low
+temperature phenomena, therefore calls for further investigations.",2110.02532v1
+2021-10-10,The influence of structural variations on the constitutive response and strain variations in thin fibrous materials,"The stochastic variations in the structural properties of thin fiber networks
+govern to a great extent their mechanical performance. To assess the influence
+of local structural variability on the local strain and mechanical response of
+the network, we propose a multiscale approach combining modeling, numerical
+simulation and experimental measurements. Based on micro-mechanical fiber
+network simulations, a continuum model describing the response at the mesoscale
+level is first developed. Experimentally measured spatial fields of thickness,
+density, fiber orientation and anisotropy are thereafter used as input to a
+macroscale finite-element model. The latter is used to simulate the impact of
+spatial variability of each of the studied structural properties. In addition,
+this work brings novelty by including the influence of the drying condition
+during the production process on the fiber properties. The proposed approach is
+experimentally validated by comparison to measured strain fields and uniaxial
+responses. The results suggest that the spatial variability in density presents
+the highest impact on the local strain field followed by thickness and fiber
+orientation. Meanwhile, for the mechanical response, the fiber orientation
+angle with respect to the drying restraints is the key influencer and its
+contribution to the anisotropy of the mechanical properties is greater than the
+contribution of the fiber anisotropy developed during the fiber sheet-making.",2110.04897v1
+2021-10-13,Electric-field control of magnetic anisotropies: applications to Kitaev spin liquids and topological spin textures,"Magnetic anisotropies often originate from the spin-orbit coupling and
+determine magnetic ordering patterns. We develop a microscopic theory for DC
+electric-field controls of magnetic anisotropies in magnetic Mott insulators
+and discuss its applications to Kitaev materials and topological spin textures.
+Throughout this paper, we take a microscopic approach based on Hubbard-like
+lattice models, tight-binding models with on-site interactions. We derive a
+low-energy spin Hamiltonian from a fourth-order perturbation expansion of the
+Hubbard-like model. We show in the presence of a strong intra-atomic spin-orbit
+coupling that DC electric fields add non-Kitaev interactions such as a
+Dzyaloshinskii-Moriya interaction and an off-diagonal $\Gamma'$ interaction to
+the Kitaev-Heisenberg model and can induce a topological quantum phase
+transition between Majorana Chern insulating phases. We also investigate the
+inter-atomic Rashba spin-orbit coupling and its effects on topological spin
+textures. DC electric fields turn out to create and annihilate magnetic
+skyrmions, hedgehogs, and chiral solitons. We propose several methods of
+creating topological spin textures with external electromagnetic fields. Our
+theory clarifies that the strong but feasible electric field can control Kitaev
+spin liquids and topological spin textures.",2110.06503v4
+2021-10-24,Isotropic finite-difference approximations for phase-field simulations of polycrystalline alloy solidification,"Phase-field models of microstructural pattern formation during alloy
+solidification are commonly solved numerically using the finite-difference
+method, which is ideally suited to carry out computationally efficient
+simulations on massively parallel computer architectures such as Graphic
+Processing Units. However, one known drawback of this method is that the
+discretization of differential terms involving spatial derivatives introduces a
+spurious lattice anisotropy that can influence the solid-liquid interface
+dynamics. We find that this influence is significant for the case of
+polycrystalline dendritic solidification, where the crystal axes of different
+grains do not generally coincide with the reference axes of the
+finite-difference lattice. In particular, we find that with the commonly used
+finite-difference implementation of the quantitative phase-field model of
+binary alloy solidification, both the operating state of the dendrite tip and
+the dendrite growth orientation are strongly affected by the lattice
+anisotropy. To circumvent this problem, we use known methods in both real and
+Fourier space to derive finite-difference approximations of leading
+differential terms in 2D and 3D that are isotropic at order $h^2$ of the
+lattice spacing $h$. Importantly, those terms include the divergence of the
+anti-trapping current that is found to have a critical influence on pattern
+selection. The 2D and 3D discretizations use an approximated form of the
+anti-trapping current that facilitates the Fourier-space derivation of the
+associated isotropic differential operator at $O(h^2)$, but we also derive a 2D
+discretization of the standard form of this current. Finally, we present 2D and
+3D phase-field simulations of alloy solidification, showing that the isotropic
+finite-difference implementations can dramatically reduce spurious lattice
+anisotropy effects.",2110.12448v1
+2021-10-27,Size-dependent enhancement of passive microwave rectification in magnetic tunnel junctions with perpendicular magnetic anisotropy,"Spintronic rf detectors were demonstrated, recently, for energy harvesting
+and wireless communication at low input power. Here we report on the
+optimization of the rectified output dc voltage using magnetic tunnel junctions
+(MTJ) with strong perpendicular anisotropy (PMA) of both the polarizing and the
+free layer. The magnetization of the polarizing layer is fixed out of plane,
+while the free layer thickness is adjusted so that its magnetization
+orientation changes from in plane to out of plane. The rectification dc output
+voltage lies in the mV range for moderate rf powers, with a signal to noise
+ratio of 10 to 100 for Prf = -25dBm. It shows a strong dependence on the
+dimensions of the MTJ: it increases by a factor of 5 to 6 when reducing the
+diameter from 150nm to 20nm. This enhancement can be doubled when reducing the
+FL thickness from 1.8nm to 1.6nm. This dimensional enhancement is attributed to
+the change of the effective anisotropy of the excited free layer, and the MTJ
+resistance. The results are of interest for the design of spintronic based rf
+detectors with optimized sensitivity.",2110.14501v1
+2021-11-08,Detectability of the cross-correlation between CMB lensing and stochastic GW background from compact object mergers,"The anisotropies of the Stochastic Gravitational-Wave Background (SGWB)
+produced by merging compact binaries constitute a possible new probe of the
+Large-Scale Structure (LSS). However, the significant shot noise contribution
+caused by the discreteness of the GW sources and the poor angular resolution of
+the instruments hamper the detection of the intrinsic anisotropies induced by
+the LSS. In this work, we investigate the potential of cross-correlating
+forthcoming high precision measurements of the SGWB energy density and the
+Cosmic Microwave Background (CMB) lensing convergence to mitigate the effect of
+shot noise. Combining a detailed model of stellar and galactic astrophysics
+with a novel framework to distribute the GW emitters in the sky, we compute the
+auto- and cross-correlation power spectra for the two cosmic fields, evaluate
+the shot noise contribution and predict the signal-to-noise ratio. The results
+of our analysis show that the SGWB energy density correlates significantly with
+the CMB lensing convergence and that the cross-correlation between these two
+cosmic fields reduces the impact of instrumental and shot noise. Unfortunately,
+the S/N is not high enough to detect the intrinsic SGWB anisotropies.
+Nevertheless, a network composed of both present and future generation GW
+interferometers, operating for at least 10 yrs, should be able to measure the
+shot noise contribution.",2111.04757v2
+2021-11-11,Current-induced superconducting anisotropy of Sr$\mathsf{_2}$RuO$\mathsf{_4}$,"In the unconventional superconductor Sr$\mathsf{_2}$RuO$\mathsf{_4}$, unusual
+first-order superconducting transition has been observed in the low-temperature
+and high-field region, accompanied by a four-fold anisotropy of the in-plane
+upper critical magnetic field $H_{c2}$. The origin of such unusual $H_{c2}$
+behavior should be closely linked to the debated superconducting symmetry of
+this oxide. Here, toward clarification of the unusual $H_{c2}$ behavior, we
+performed the resistivity measurements capable of switching in-plane current
+directions as well as precisely controlling the field directions. Our results
+reveal that resistive $H_{c2}$ under the in-plane current exhibits an
+additional two-fold anisotropy. By systematically analyzing $H_{c2}$ data taken
+under various current directions, we succeeded in separating the two-fold
+$H_{c2}$ component into the one originating from applied current and the other
+originating from certain imperfection in the sample. The former component,
+attributable to vortex flow effect, is weakened at low temperatures where
+$H_{c2}$ is substantially suppressed. The latter component is enhanced in the
+first order transition region, possibly reflecting a change in the nature of
+the superconducting state under high magnetic field.",2111.06097v1
+2021-11-22,Magnetization Reversal in Two-dimensional Ensemble of Nanoparticles with Positional Defects,"We study relaxation behaviour in the two-dimensional assembly of magnetic
+nanoparticles (MNPs) with aligned anisotropy axes and positional defects. The
+anisotropy axes orientation and disorder strength is changed by varying
+$\alpha$ and $\Delta$, respectively. The magnetization decay does not depend on
+the aspect ratio $A^{}_r$ of the system and $\Delta$ for small dipolar
+interaction strength $h^{}_d=0.2$. Remarkably, the magnetization decays rapidly
+for considerable $h^{}_d$ with negligible $\Delta$ and $A_r=1.0$. The dipolar
+interaction of enough strength promotes antiferromagnetic coupling in square
+ensembles of MNPs. There is a prolonged magnetization decay for large $\Delta$
+because of enhancement in ferromagnetic coupling. Notably, magnetization
+relaxes slowly for $\alpha<\alpha^\star$ even with moderate $h^{}_d$ and a
+significant $A^{}_r$. Interestingly, the slowing down of the magnetic
+relaxation shifts to a lower $\alpha^{\star}$ with $h^{}_d=1.0$. The
+magnetization ceases to relax for $\alpha\leq60^\circ$ and $h^{}_d\leq0.6$ due
+to large shape anisotropy with $A^{}_r=400.0$. Remarkably, a majority of the
+magnetic moment reverses its direction by $180^\circ$ for $\alpha>60^\circ$ and
+large $h^{}_d$, resulting in the negative magnetization. The effective N\'eel
+relaxation time $\tau^{}_N$ also depends strongly on these parameters.
+$\tau^{}_N$ depends weakly on $\alpha$ and $\Delta$ for $h^{}_d\leq0.2$,
+irrespective of $A^{}_r$. On the other hand, $\tau^{}_N$ decreases with
+$\alpha$ for significant $h^{}_d$ provided $\alpha$ is greater than $45^\circ$
+because of antiferromagnetic coupling dominance. In a highly anisotropic
+system, there is an enhancement in $\tau^{}_N$ with $\alpha$ ($\leq30^\circ$)
+even with moderate $h^{}_d$. While for $\alpha>30^\circ$, $\tau^{}_N$ decreases
+with $\alpha$. These observations are useful in novel materials, spintronics
+based applications, etc.",2111.11034v1
+2021-11-23,ChebLieNet: Invariant Spectral Graph NNs Turned Equivariant by Riemannian Geometry on Lie Groups,"We introduce ChebLieNet, a group-equivariant method on (anisotropic)
+manifolds. Surfing on the success of graph- and group-based neural networks, we
+take advantage of the recent developments in the geometric deep learning field
+to derive a new approach to exploit any anisotropies in data. Via discrete
+approximations of Lie groups, we develop a graph neural network made of
+anisotropic convolutional layers (Chebyshev convolutions), spatial pooling and
+unpooling layers, and global pooling layers. Group equivariance is achieved via
+equivariant and invariant operators on graphs with anisotropic left-invariant
+Riemannian distance-based affinities encoded on the edges. Thanks to its simple
+form, the Riemannian metric can model any anisotropies, both in the spatial and
+orientation domains. This control on anisotropies of the Riemannian metrics
+allows to balance equivariance (anisotropic metric) against invariance
+(isotropic metric) of the graph convolution layers. Hence we open the doors to
+a better understanding of anisotropic properties. Furthermore, we empirically
+prove the existence of (data-dependent) sweet spots for anisotropic parameters
+on CIFAR10. This crucial result is evidence of the benefice we could get by
+exploiting anisotropic properties in data. We also evaluate the scalability of
+this approach on STL10 (image data) and ClimateNet (spherical data), showing
+its remarkable adaptability to diverse tasks.",2111.12139v1
+2021-11-23,The CMB Dipole: Eppur Si Muove,"The largest temperature anisotropy in the cosmic microwave background (CMB)
+is the dipole. The simplest interpretation of the dipole is that it is due to
+our motion with respect to the rest frame of the CMB. As well as creating the
+$\ell$=1 mode of the CMB sky, this motion affects all astrophysical
+observations by modulating and aberrating sources across the sky. It can be
+seen in galaxy clustering, and in principle its time derivative through a
+dipole-shaped acceleration pattern in quasar positions. Additionally, the
+dipole modulates the CMB temperature anisotropies with the same frequency
+dependence as the thermal Sunyaev-Zeldovich (tSZ) effect and so these modulated
+CMB anisotropies can be extracted from the tSZ maps produced by Planck.
+Unfortunately, this measurement cannot determine if the dipole is due to our
+motion, but it does provide an independent measure of the dipole and a
+validation of the y maps. This measurement, and a description of the
+first-order terms of the CMB dipole, are outlined here.",2111.12186v1
+2021-11-24,Effect of chemical disorder on the magnetic anisotropy in L$1_0$ FeNi from first principles calculations,"We use first principles calculations to investigate how deviations from
+perfect chemical order affect the magneto-crystalline anisotropy energy (MAE)
+in L$1_0$ FeNi. We first analyze the local chemical environment of the Fe atoms
+in various partially ordered configurations, using the orbital magnetic moment
+anisotropy (OMA) as proxy for a local contribution to the MAE. We are able to
+identify a specific nearest neighbor configuration and use this ""favorable
+environment"" to successfully design various structures with MAE higher than the
+perfectly ordered system. However, a systematic analysis of the correlation
+between local environment and OMA using smooth overlap of atomic positions
+(SOAP), indicates only a partial correlation, which exists only if the
+deviation from full chemical order is not too large, whereas in general no such
+correlation can be identified even using up to third nearest neighbors. Guided
+by the observation that the identified ""favorable environment"" implies an
+Fe-rich composition, we investigate the effect of randomly inserting additional
+Fe into the nominal Ni planes of the perfectly ordered structure. We find that
+the MAE increases with Fe content, at least up to 62.5% Fe. Thus, our study
+shows that the perfectly ordered case is not the one with highest MAE and that
+an increased MAE can be obtained for slightly Fe-rich compositions.",2111.12492v3
+2021-11-25,Manifestation of the anisotropic properties of the molecular J-aggregate shell in optical spectra of plexcitonic nanoparticles,"The theoretical studies of light absorption and scattering spectra of the
+plexcitonic two-layer triangular nanoprisms and three-layer nanospheres are
+reported. The optical properties of such metal-organic core--shell and
+core--double-shell nanostructures were previously explained within the
+framework of pure isotropic models for describing their outer excitonic shell.
+In this work, we show that the anisotropy of the excitonic shell permittivity
+can drastically affect the optical spectra of such hybrid nanostructures. This
+fact is confirmed by directly comparing our theory with some available
+experimental data, which cannot be treated using conventional isotropic shell
+models. We have analyzed the influence of the shell anisotropy on the optical
+spectra and proposed a type of hybrid nanostructure that seems most convenient
+for experimental observation of the effects associated with the anisotropy of
+the excitonic shell. A strong dependence of the anisotropic properties of the
+J-aggregate shell on the material of the intermediate spacer layer is
+demonstrated. This allows proposing a new way to effectively control the
+optical properties of metal-organic nanostructures by selecting the spacer
+material. Our results extend the understanding of physical effects in optics of
+plexcitonic nanostructures to more complex systems with the anisotropic and
+multi-excitonic properties of their molecular aggregate shell.",2111.13126v1
+2021-11-26,Open quantum dynamics theory for a complex subenvironment system with a quantum thermostat: Application to a spin heat bath,"Complex environments, such as molecular matrices and biological material,
+play a fundamental role in many important dynamic processes in condensed
+phases. Because it is extremely difficult to conduct full quantum dynamics
+simulations on such environments due to their many degrees of freedom, here we
+treat in detail the environment only around the main system of interest (the
+subenvironment), while the other degrees of freedom needed to maintain the
+equilibrium temperature are described by a simple harmonic bath, which we call
+a quantum thermostat. The noise generated by the subenvironment is spatially
+non-local and non-Gaussian and cannot be characterized by the
+fluctuation-dissipation theorem. We describe this model by simulating the
+dynamics of a two-level system (TLS) that interacts with a subenvironment
+consisting of a one-dimensional $XXZ$ spin chain. The hierarchical
+Schr\""odinger equations of motion are employed to describe the quantum
+thermostat, allowing time-irreversible simulations of the dynamics at arbitrary
+temperature. To see the effects of a quantum phase transition of the
+subenvironment, we investigate the decoherence and relaxation processes of the
+TLS at zero and finite temperatures for various values of the spin anisotropy.
+We observed the decoherence of the TLS at finite temperature, even when the
+anisotropy of the $XXZ$ model is enormous. We also found that the population
+relaxation dynamics of the TLS changed in a complex manner with the change of
+the anisotropy and the ferromagnetic or antiferromagnetic orders of the spins.",2111.13277v1
+2021-11-27,Effect of Rashba and Dresselhaus spin-orbit coupling on supercurrent rectification and magnetochiral anisotropy of ballistic Josephson junctions,"Simultaneous breaking of inversion- and time-reversal symmetry in Josephson
+junction leads to a possible violation of the $I(\varphi)=-I(-\varphi)$
+equality for the current-phase relation. This is known as anomalous Josephson
+effect and it produces a phase shift $\varphi_0$ in sinusoidal current-phase
+relations. In ballistic Josephson junctions with non-sinusoidal current phase
+relation the observed phenomenology is much richer, including the supercurrent
+diode effect and the magnetochiral anisotropy of Josephson inductance. In this
+work, we present measurements of both effects on arrays of Josephson junctions
+defined on epitaxial Al/InAs heterostructures. We show that the orientation of
+the current with respect to the lattice affects the magnetochiral anisotropy,
+possibly as the result of a finite Dresselhaus component. In addition, we show
+that the two-fold symmetry of the Josephson inductance reflects in the
+activation energy for phase slips.",2111.13983v2
+2021-11-29,Single-pulse all-optical switching in amorphous Dy$_x$Co$_{1-x}\text{ }$ and Tb$_x$Co$_{1-x}$,"Repeated uniform switching of the magnetization of thin films of
+ferrimagnetic amorphous Gd$_{x}$(FeCo)$_{1-x}$ in response to single fast laser
+pulses is well established. Here we report unusual toggle switching in thin
+films of sperimagnetic amorphous Dy$_x$Co$_{1-x}$ and Tb$_x$Co$_{1-x}$ with
+$\it{x} \simeq$ 0.25 irradiated with single 200 fs pulses of 800 nm laser
+light. The samples have strong local random anisotropy due to the non-S state
+rare earth. The compensation temperature of the films is $\le$ 180 K and their
+Curie temperature is $\simeq$ 500 K. They are mostly switched by the first
+pulse, and subsequent pulses lead to partial re-switching of a decreasing
+amount of the irradiated area, with a granular structure of submicron regions
+of switched and unswitched material. Individual switched domains about 700 nm
+in size are observed around the edge of the irradiated spots where the fluence
+is at the threshold for switching. Results are discussed in terms of a random
+anisotropy model where the ratio of local anisotropy to exchange is temperature
+dependent and close to the threshold for strong pinning.",2111.14587v1
+2021-11-30,SIRIUS Project. IV. The formation history of the Orion Nebula Cluster driven by clump mergers,"The Orion Nebula Cluster (ONC) is an excellent example for understanding the
+formation of star clusters. Recent studies have shown that ONC has three
+distinct age populations and anisotropy in velocity dispersions, which are key
+characteristics for understanding the formation history of the ONC. In this
+study, we perform a smoothed-particle hydrodynamics/$N$-body simulation of star
+cluster formation from a turbulent molecular cloud. In this simulation, stellar
+orbits are integrated using a high-order integrator without gravitational
+softening; therefore, we can follow the collisional evolution of star clusters.
+We find that hierarchical formation causes episodic star formation that is
+observed in the ONC. In our simulation, star clusters evolve due to mergers of
+subclumps. The mergers bring cold gas with the clumps into the forming cluster.
+This enhances the star formation in the cluster centre. The dense cold gas in
+the cluster centre continues to form stars until the latest time. This explains
+the compact distribution of the youngest stars observed in the ONC. Subclump
+mergers also contribute to the anisotropy in the velocity dispersions and the
+formation of runaway stars. However, the anisotropy disappears within 0.5 Myr.
+The virial ratio of the cluster also increases after a merger due to the
+runaways. These results suggest that the ONC recently experienced a clump
+merger. We predict that most runaways originated from the ONC have already been
+found, but walkaways have not.",2111.15154v2
+2021-12-03,Bianchi IX gravitational collapse of matter inhomogeneities,"We investigate a model of gravitational collapse of matter inhomogeneities
+where the latter are modelled as Bianchi type IX (BIX) spacetimes. We found
+that this model contains, as limiting cases, both the standard spherical
+collapse model and the Zeldovich solution for a 1-dimensional perturbation. We
+study how these models are affected by small anisotropic perturbations within
+the BIX potential. For the spherical collapse case, we found that the model is
+equivalent to a closed FLRW Universe filled with matter and two perfect fluids
+representing the anisotropic contributions. From the linear evolution up to the
+turnaround, the anisotropies effectively shift the value of the FLRW spatial
+curvature, because the fluids have effective Equation of State (EoS) parameters
+$w \approx -1/3$. Then we estimate the impact of such anisotropies on the
+number density of haloes using the Press-Schechter formalism. If a fluid
+description of the anisotropies is still valid after virialization, the
+averaged over time EoS parameters are $w\approx 1/3$. Using this and demanding
+hydrostatic equilibrium, we find a relation between the mass $M$, the average
+radius $R$ and the pressure $p$ of the virialized final structure. When we
+consider perturbations of the Zeldovich solution, our qualitative analysis
+suggests that the so called \textit{pancakes} exhibit oscillatory behavior, as
+would be expected in the case of a vacuum BIX spacetime.",2112.01869v2
+2021-12-06,A Novel Full-Polarization SAR Images Ship Detector Based on the Scattering Mechanisms and the Wave Polarization Anisotropy,"Synthetic aperture radar (SAR) is considered being a good option for earth
+observation with its unique advantages. In this paper, we proposed an adaptive
+ship detector using full-polarization SAR images. First, by thoroughly
+investigating the scattering characteristics between ships and their
+background, and the wave polarization anisotropy, a novel ship detector is
+proposed by jointing the two characteristics, named Scattering-Anisotropy joint
+(joint-SA). Based on the theoretical analysis, we showed that the joint-SA is
+an effective physical quantity to show the difference between the ship and its
+background, and thus joint-SA can be used for ship detection of
+full-polarization image data. Second, the generalized Gamma distribution was
+used to characterize the joint-SA statistics of sea clutter with a large range
+of homogeneity. As a result, an adaptive constant false alarm rate (CFAR)
+method was implemented based on the joint-SA. Finally, RADARSAT-2 and GF-3 data
+in C-band and ALOS data in L-band are used for verification. We tested on five
+datasets, and the experimental results verify the correctness and superiority
+of the constant false alarm rate (CFAR) method based on the joint-SA. In
+addition, the experimental results also showed that the signal-clutter ratio
+(SCR) of the proposed ship detector joint-SA (33.17 dB, 35.98 dB, 57.25 dB) is
+better than that of DBSP (8.92 dB, 3.43 dB, 25.40 dB) and RsDVH (17.28 dB,
+11.17 dB, 54.55 dB). More importantly, the proposed detector joint-SA has
+higher detection accuracy and a lower false alarm rate.",2112.02965v2
+2021-12-09,Nonlinear optical imaging of in-plane anisotropy in two-dimensional SnS,"Two-dimensional (2D) tin(II) sulfide (SnS) crystals belong to a class of
+orthorhombic semiconducting materials that are lately attracting significant
+interest, given their remarkable properties, such as in-plane anisotropic
+optical and electronic response, multiferroic nature and lack of inversion
+symmetry. The 2D SnS crystals exhibit anisotropic response along the in-plane
+armchair (AC) and zigzag (ZZ) crystallographic directions, offering an
+additional degree of freedom in manipulating their behavior. Therefore,
+calculating the AC/ZZ directions is important in characterizing the 2D SnS
+crystals. In this work, we take advantage of the lack of inversion symmetry of
+the 2D SnS crystal, that produces second harmonic generation (SHG), to perform
+polarization-resolved SHG (P-SHG) nonlinear imaging of the in-plane anisotropy.
+We fit the P-SHG experimental data with a nonlinear optics model, that allows
+us to calculate the AC/ZZ orientation from every point of the 2D crystal and to
+map with high-resolution the AC/ZZ direction of several 2D SnS flakes belonging
+in the same field of view. It is found that the P-SHG intensity polar patterns
+are associated with the crystallographic axes of the flakes and with the
+relative strength of the second order nonlinear susceptibility tensor in
+different directions. Therefore, our method provides quantitative information
+of the optical in-plane anisotropy of orthorhombic 2D crystals, offering great
+promise for performance characterization during device operation in the
+emerging optoelectronic applications of such crystals.",2112.04853v1
+2021-12-10,Low-energy excitations and magnetic anisotropy of the layered van der Waals antiferromagnet Ni$_2$P$_2$S$_6$,"The quasi-two-dimensional antiferromagnet Ni$_2$P$_2$S$_6$ belongs to the
+family of magnetic van der Waals compounds that provides a rich material base
+for the realization of fundamental models of quantum magnetism in low
+dimensions. Here, we report high-frequency/high-magnetic field electron spin
+resonance measurements on single crystals of Ni$_2$P$_2$S$_6$. The results
+enable one to reliably determine the positive, ""easy""-plane type of the single
+ion anisotropy of the Ni$^{2+}$ ions with the upper limit of its magnitude
+$\lesssim 0.7$ meV. The resonance response reveals strongly anisotropic spin
+fluctuations setting in shortly above the N\'eel temperature $T_{\rm N} = 158$
+K and extending in the antiferromagnetically ordered state down to low
+temperatures. There, a low-energy magnon excitation gapped from the ground
+state by only $\sim 1$ meV was found. This magnon mode may explain unusual low
+temperature relaxation processes observed in a latest nuclear magnetic
+resonance experiments and together with the estimate of the single ion
+anisotropy they should enable setting up a realistic spin model for an accurate
+description of magnetic properties of Ni$_2$P$_2$S$_6$.",2112.05699v3
+2021-12-20,"Refined modelling of the radio SZ signal: kinematic terms, relativistic temperature corrections and anisotropies in the radio background","A significant cosmological radio background will inevitably lead to a radio
+Sunyaev-Zeldovich (SZ) effect. In the simplest limit, the combined signal from
+the scattered radio and cosmic microwave background exhibits a null at around
+$\nu \simeq 735$ MHz. Here, we show that kinematic and relativistic temperature
+corrections to this radio SZ signal are easily calculable. We treat both the
+cluster and observer motion, and the scattering of anisotropies in the radio
+background, highlighting how the spectrum of the radio SZ effect is affected in
+each case. Although relativistic temperature corrections only enter at the
+level of a few percent, our expressions allow high-precision modelling of these
+terms. By measuring the SZ signal around the radio null, one is in principle
+able to place constraints on the properties of a cosmological radio background.
+A combination with standard SZ measurements from large cluster samples could
+provide a promising avenue towards breaking degeneracies between different
+contributions. Stacking analyses can reduce the effect of kinematic corrections
+and dipolar anisotropies in the radio background, thereby providing a way to
+constrain the redshift dependence of the average radio background. Our
+qualitative discussion is meant to give an analytic understanding of the
+various effects and also motivate further studies with the aim to obtain
+quantitative forecasts of their observability. At this stage, a detection of
+the corrections seems rather futuristic, but the advent of large SZ and X-ray
+cluster samples could drastically improve our ability to disentangle various
+effects.",2112.10666v2
+2021-12-23,DyOCl: a rare-earth based two-dimensional van der Waals material with strong magnetic anisotropy,"Comparing with the widely known transitional metal based van der Waals (vdW)
+materials, rare-earth based ones are rarely explored in the research of
+intrinsic two-dimensional (2D) magnetism. In this work, we report the physical
+properties of DyOCl, a rare-earth based vdW magnetic insulator with direct band
+gap of $\sim 5.72~eV$. The magnetic order of bulk DyOCl is determined by
+neutron scattering as the $A$-type antiferromagnetic structure below the
+N\'{e}el temperature $T_N=10~$K. The large magnetic moment near 10.1 $ \mu_{B}
+$/Dy lies parallel to the $a$-axis with strong uniaxial magnetic anisotropy. At
+$2~K$, a moderate magnetic field ($\sim 2~T$) applied along the easy axis
+generates spin-flip transitions and polarizes DyOCl to a ferromagnetic state.
+Density functional theory calculations reveal an extremely large magnetic
+anisotropy energy ($-5850~\mu eV/Dy$) for DyOCl, indicating the great
+potentials to realize magnetism in 2D limit. Furthermore, the mechanical
+exfoliation of bulk DyOCl single crystals down to seven layers is demonstrated.
+Our findings suggest DyOCl is a promising material playground to investigate 2D
+$f$-electron magnetism and spintronic applications at the nanoscale.",2112.12556v1
+2021-12-27,The incompressible energy cascade rate in anisotropic solar wind turbulence,"Context. The presence of a magnetic guide field induces several types of
+anisotropy in solar wind turbulence. The energy cascade rate between scales in
+the inertial range depends strongly on the direction of this magnetic guide
+field, splitting the energy cascade according to the parallel and perpendicular
+directions with respect to magnetic guide field. Aims. Using more than two
+years of Parker Solar Probe (PSP) observations, the isotropy and anisotropy
+energy cascade rates are investigated. The variance and normalized fluctuation
+ratios, the kinetic and magnetic energies, and the normalized cross-helicity
+and residual energy are studied. The connection between the heliocentric
+distance, the local temperature of the plasma, and the energy cascade
+components is made. Methods. Using exact relations for fully developed
+incompressible magnetohydrodynamic (MHD) turbulence, the incompressible energy
+cascade rate is computed. In particular, using the isotropy and 2D and slab
+assumptions, the isotropic, perpendicular, and parallel energy cascade rate
+components are estimated. Results. The variance anisotropy ratios, for both
+velocity and magnetic fields, do not exhibit a dependence with respect to the
+heliocentric distance $r$ between 0.2 and 0.8 au. While the velocity normalized
+fluctuation ratio shows a dependence with $r$, the magnetic normalized
+fluctuation ratio does not. A strong correlation between the isotropic and
+anisotropic energy cascade rates and the temperature is found. A clear
+dominance of the perpendicular cascades over the parallel cascades as PSP
+approaches the Sun is observed. A dominant 2D cascade and/or geometry over the
+slab component in slow solar wind turbulence in the largest MHD scales is
+observed.",2112.13748v3
+2022-01-01,Multiple stellar populations in Schwarzschild modeling and the application to the Fornax dwarf,"Dwarf spheroidal (dSph) galaxies are believed to be strongly dark matter
+dominated and thus are considered perfect objects to study dark matter
+distribution and test theories of structure formation. They possess resolved,
+multiple stellar populations that offer new possibilities for modeling. A
+promising tool for the dynamical modeling of these objects is the Schwarzschild
+orbit superposition method. In this work we extend our previous implementation
+of the scheme to include more than one population of stars and a more general
+form of the mass-to-light ratio function. We tested the improved approach on a
+nearly spherical, gas-free galaxy formed in the cosmological context from the
+Illustris simulation. We modeled the binned velocity moments for stars split
+into two populations by metallicity and demonstrate that in spite of larger
+sampling errors the increased number of constraints leads to significantly
+tighter confidence regions on the recovered density and velocity anisotropy
+profiles. We then applied the method to the Fornax dSph galaxy with stars
+similarly divided into two populations. In comparison with our earlier work, we
+find the anisotropy parameter to be slightly increasing, rather than
+decreasing, with radius and more strongly constrained. We are also able to
+infer anisotropy for each stellar population separately and find them to be
+significantly different.",2201.00151v1
+2022-01-19,Effects of anisotropy and disorder on the superconducting properties of Niobium,"We report results for the superconducting transition temperature and
+anisotropic energy gap for pure Niobium based on Eliashberg's equations and
+electron and phonon band structures computed from density functional theory.
+The electronic band structure is used to construct the Fermi surface and
+calculate the Fermi velocity at each point on the Fermi surface.The phonon
+bands are in excellent agreement with inelastic neutron scattering data. The
+corresponding phonon density of states and electron-phonon coupling define the
+electron-phonon spectral function, $\alpha^2F({\bf p},{\bf p}';\omega)$, and
+the corresponding electron-phonon pairing interaction, which is the basis for
+computing the superconducting properties. The electron-phonon spectral function
+is good agreement with existing tunneling spectroscopy data except for the
+spectral weight of the longitudinal phonon peak at
+$\hbar\omega_{\text{LO}}=23\,\mbox{meV}$. We obtain an electron-phonon coupling
+constant of $\lambda=1.057$, renormalized Coulomb interaction,
+$\mu^{\star}=0.218$ and transition temperature $T_c=9.33\,\mbox{K}$. The
+corresponding strong-coupling gap at $T=0$ is modestly enhanced,
+$\Delta_0=1.55\,\mbox{meV}$, compared to the weak-coupling BCS value
+$\Delta_0^{\text{wc}}=1.78\,k_{\mbox{b}}\,T_c= 1.43\,\mbox{meV}$. The
+superconducting gap function exhibits substantial anisotropy on the Fermi
+surface. We analyze the distribution of gap anisotropy and compute the
+suppression of the superconducting transition temperature using a
+self-consistent T-matrix theory for quasiparticle-impurity scattering to
+describe Niobium doped with non-magnetic impurities. We compare these results
+with experimental results on Niobium SRF cavities doped with Nitrogen
+impurities.",2201.07403v2
+2022-01-23,Valley-polarized quantum anomalous Hall insulator in monolayer $\mathrm{RuBr_2}$,"Coexistence of intrinsic ferrovalley (FV) and nontrivial band topology
+attracts intensive interest both for its fundamental physics and for its
+potential applications, namely valley-polarized quantum anomalous Hall
+insulator (VQAHI). Here, based on first-principles calculations by using
+generalized gradient approximation plus $U$ (GGA+$U$) approach, the VQAHI
+induced by electronic correlation or strain can occur in monolayer
+$\mathrm{RuBr_2}$. For perpendicular magnetic anisotropy (PMA), the ferrovalley
+(FV) to half-valley-metal (HVM) to quantum anomalous Hall (QAH) to HVM to FV
+transitions can be driven by increasing electron correlation $U$. However,
+there are no special QAH states and valley polarization for in-plane magnetic
+anisotropy. By calculating actual magnetic anisotropy energy (MAE), the VQAHI
+indeed can exist between two HVM states due to PMA, a unit Chern number/a
+chiral edge state and spontaneous valley polarization. The increasing $U$ can
+induce VQAHI, which can be explained by sign-reversible Berry curvature or band
+inversion between $d_{xy}$/$d_{x^2-y^2}$ and $d_{z^2}$ orbitals. Even though
+the real $U$ falls outside the range, the VQAHI can be achieved by strain.
+Taking $U$$=$2.25 eV as a concrete case, the monolayer $\mathrm{RuBr_2}$ can
+change from a common ferromagentic (FM) semiconductor to VQAHI under about
+0.985 compressive strain. It is noted that the edge states of VQAHI are
+chiral-spin-valley locking, which can achieve complete spin and valley
+polarizations for low-dissipation electronics devices. Both energy band gap and
+valley splitting of VQAHI in monolayer $\mathrm{RuBr_2}$ are higher than the
+thermal energy of room temperature (25 meV), which is key at room temperature
+for device applications.",2201.09258v1
+2022-02-04,Three-axis torque investigation of interfacial exchange coupling in a NiFe/CoO bilayer micromagnetic disk,"Micrometer diameter bilayers of NiFe (permalloy, Py) and cobalt oxide (CoO)
+deposited on nanomechanical resonators were used to investigate exchange bias
+effects. The mechanical compliances of two resonator axes were enhanced by
+severing one torsion arm, resulting in a unique three-axis resonator that
+responds resonantly to torques generated by a three-axis RF field. Our
+technique permits simultaneous measurement of three orthogonal torque
+components. Measurements of the anisotropies associated with interfacial
+exchange coupling effects have been made. At cryogenic temperatures,
+observations of shifted linear hysteresis loops confirmed the presence of
+exchange bias from the Py/CoO interface. An in-plane rotating DC bias field was
+used to probe in-plane anisotropies through the out-of-plane torque. Training
+effects in the rotational hysteresis data were observed and showed that
+features due to interfacial coupling did not diminish irrespective of
+substantial training of the unidirectional anisotropy. The data from the
+rotational hysteresis loops were fit with parameters from a macrospin solution
+to the Landau-Lifshitz-Gilbert equation. Each parameter of the exchange bias
+model accounts for specific features of the rotational loop.",2202.02386v1
+2022-02-11,Interaction between interface and massive states in multivalley topological heterostructures,"Topological interface states in multivalley systems are studied to unravel
+their valley sensitivity. For this purpose, multivalley IV-VI topological
+crystalline insulator (TCI) heterostructures are explored using magneto-optical
+Landau level spectroscopy up to 34 teslas. We characterize the topological
+interface states emerging from the distinct L-valleys in Pb1-xSnxSe multi
+quantum wells grown along the [111] direction. It is shown that the shape of
+the 2D Fermi surfaces of topological interface states residing at the
+TCI/trivial insulator interfaces are strongly affected by the valley anisotropy
+of topologically trivial Pb1-yEuySe barriers. This phenomenon is shown to be
+due to the deep penetration of the topological interface states into the
+barriers. For the valleys tilted with respect to the confinement direction, a
+significant interaction between topological states and the conventional massive
+quantum well states is observed, evidenced by the resulting large
+anti-crossings between Landau levels. These are theoretically well-described by
+a k.p model that takes into account tilt and anisotropy of the valleys in two
+dimensions. Therefore, our work provides a precise characterization of the
+topological interface state valley splitting, as well as an accurate
+determination of the anisotropy of their Dirac cone dispersion.",2202.05640v1
+2022-02-24,"Explaining the UHECR spectrum, composition and large-scale anisotropies with radio galaxies","Radio galaxies are promising candidates as the sources of ultrahigh energy
+cosmic rays (UHECRs). In this work, we examine if the stringent constraints
+imposed by the dipole and quadropole anisotropies as well as the UHECR spectrum
+and composition allow that radio galaxies are the dominant extragalactic cosmic
+ray sources. In order to calculate the UHECR flux emitted by individual radio
+galaxies, we constrain their properties using information from the radio-CR
+correlation and a dynamical evolution model. In addition to the UHECR flux from
+individual, local sources, we include the diffuse flux emitted by the bulk of
+non-local radio galaxies based on their radio luminosity distribution.
+Analyzing the source parameters within a range around their expected
+properties, we finally determine the configurations of local sources describing
+well the UHECR spectrum, composition and large-scale anisotropies. We obtain a
+good description of all data even in the case that we include only a small
+number of local sources. In particular, we find that scenarios where few
+sources like Fornax A and Virgo A dominate the flux above the ankle, while
+low-luminosity radio galaxies contribute an isotropic background dominating
+below the ankle, provide a good fit to the data.",2202.11942v2
+2022-02-28,Large perpendicular magnetic anisotropy of transition metal dimers driven by polarization switching of two-dimensional ferroelectric In2Se3 substrate,"Large perpendicular magnetic anisotropy (MA) is highly desirable for
+realizing atomic-scale magnetic data storage which represents the ultimate
+limit of the density of magnetic recording. In this work, we studied the MA of
+transition metal dimers Co-Os, Co-Co and Os-Os adsorbed on two-dimensional
+ferroelectric In2Se3 (In2Se3-CoOs, In2Se3-OsCo, In2Se3-CoCo and In2Se3-OsOs) by
+first-principles calculations. It is found that the Co-Os dimer in In2Se3-CoOs
+has large total perpendicular magnetic anisotropy energy (MAE) of ~ 40 meV. In
+particular, the MAE arising from Os atom is up to ~ 60 meV. The large MAE is
+attributed to the high spin-orbit coupling constant and the onefold
+coordination of Os atom. In addition, the MA of the dimers can be tuned by the
+polarization reversal of In2Se3. When the polarization is upward, the easy-axis
+directions of MA in In2Se3-OsCo, In2Se3-CoCo and In2Se3-OsOs are all in-plane,
+while the directions become perpendicular as the polarization is switched to
+downward. For the In2Se3-CoOs, switching polarization from upward to downward
+enhance the perpendicular MA from ~ 20 meV to ~ 40 meV. Based on the
+second-order perturbation theory, we confirm that the exchange splitting of
+dxy/dx2-y2 and dxz/dyz orbitals as well as the occupation of dz2 orbital at the
+vicinity of Fermi level play important roles in the changes of MA with the
+reversal of FE polarization of In2Se3.",2202.13726v1
+2022-03-08,Can Chameleon fields be the source of both the dark energy dipole and the CMB dipole?,"Recent research shows that the local group is moving toward (l,b)=(276,30)
+relative to the cosmic background radiation at a speed of about $600 kms^{-1}$
+which is known as the cosmic background radiation dipole. The exact cause of
+this movement is still unknown. Areas with high mass densities such as galactic
+superclusters seem to be one of the causes of this flow. There are several
+methods for simulating the motion of local clusters, one of which is the bulk
+flow. The bulk current can be seen as a mass movement of a large part of the
+universe. This anisotropy at the local scale seems to have the same origin as
+the anisotropy at the larger scale. In this paper, anisotropies on both small
+and large scales were investigated using chameleon fields. The data used are
+Type Ia supernovae (Pantheon catalog for a total of 1,048 supernovae in
+redshift (0.15<z<2.3)). The results showed that on a smaller scale (less than
+150 MPa) the direction of motion of the local group galaxies is the same as the
+direction of the bulk, and on larger scales, the direction of the bulk current
+is the same as the direction of the current of dark energy dipole.",2203.03983v1
+2022-03-08,Early dynamical evolution of rotating star clusters in a tidal field,"In order to explore how the early internal rotational properties of star
+clusters are affected by the external potential of their host galaxies, we have
+run a suite of $N$-body simulations following the early dynamical evolution and
+violent relaxation of rotating star clusters embedded in a tidal field. Our
+study focuses on models for which the cluster's rotation axis has a generic
+orientation relative to the torque of the tidal field. The interaction between
+the violent relaxation process, angular momentum of the cluster, and the
+external torque creates a complex kinematic structure within the cluster, most
+prominently a radial variation in the position of the rotation axis along both
+the polar and azimuthal directions. We also examine the cluster's velocity
+dispersion anisotropy and show that the projected anisotropy may be affected by
+the variation of the rotation axis directions within the cluster; the
+combination of projection effects and the complex kinematical features may
+result in the measurement of tangential anisotropy in the cluster's inner
+regions. We also characterize the structural properties of our clusters as a
+function of their initial rotation and virial ratio and find that clusters may
+develop a triaxial morphology and a radial variation of the minor axis not
+necessarily aligned with the rotation axis. Finally, we examine the long-term
+evolution of these complex kinematic features.",2203.04330v1
+2022-03-24,Simulating realistic screening clouds around quantum impurities: role of spatial anisotropy and disorder,"Dynamical quantum impurities in metals induce electronic correlations in real
+space that are difficult to simulate due to their multi-scale nature, so that
+only s-wave scattering in clean metallic hosts has been investigated so far.
+However, screening clouds should show anisotropy due to lack of full rotational
+invariance in two- and three-dimensional lattices, while inherent disorder will
+also induce spatial inhomogeneities. To tackle these challenges, we present an
+efficient and robust algorithm based on the recursive generation of natural
+orbitals defined as eigenvectors of the truncated single-particle density
+matrix. This method provides well-converged many-body wave functions on
+lattices with up to tens of thousands of sites, bypassing some limitations of
+other approaches. The algorithm is put to the test by investigating the charge
+screening cloud around an interacting resonant level, both on clean and
+disordered lattices, achieving accurate spatial resolution from short to long
+distances. We thus demonstrate strong anisotropy of spatial correlations around
+an adatom in the half-filled square lattice. Taking advantage of the efficiency
+of the algorithm, we further compute the disorder-induced distribution of Kondo
+temperatures over several thousands of random realizations, at the same time
+gaining access to the full spatial profile of the screening cloud in each
+sample. While the charge screening cloud is typically shortened due to the
+polarization of the impurity by the disorder potential, we surprisingly find
+that rare disorder configurations preserve the long range nature of Kondo
+correlations in the electronic bath.",2203.13041v1
+2022-03-25,"Optical constants of several multilayer transition metal dichalcogenides measured by spectroscopic ellipsometry in the 300-1700 nm range: high-index, anisotropy, and hyperbolicity","Transition metal dichalcogenides (TMDs) attract significant attention due to
+their exceptional optical and excitonic properties. It was understood already
+in the 1960s, and recently rediscovered, that many TMDs possess high refractive
+index and optical anisotropy, which make them attractive for nanophotonic
+applications. However, accurate analysis and predictions of nanooptical
+phenomena require knowledge of dielectric constants along both in- and
+out-of-plane directions and over a broad spectral range -- information, which
+is often inaccessible or incomplete. Here, we present an experimental study of
+optical constants from several exfoliated TMD multilayers obtained using
+spectroscopic ellipsometry in the broad range of 300--1700 nm. The specific
+materials studied include semiconducting WS$_2$, WSe$_2$, MoS$_2$, MoSe$_2$,
+MoTe$_2$, as well as, in-plane anisotropic ReS$_2$, WTe$_2$, and metallic
+TaS$_2$, TaSe$_2$, and NbSe$_2$. The extracted parameters demonstrate
+high-index ($n$ up till $\approx 4.84$ for MoTe$_2$), significant anisotropy
+($n_{\parallel}-n_{\perp} \approx 1.54$ for MoTe$_2$), and low absorption in
+the near infrared region. Moreover, metallic TMDs show potential for combined
+plasmonic-dielectric behavior and hyperbolicity, as their plasma frequency
+occurs at around $\sim$1000--1300 nm depending on the material. The knowledge
+of optical constants of these materials opens new experimental and
+computational possibilities for further development of all-TMD nanophotonics.",2203.13793v1
+2022-03-31,Anomalous Hall Effect and Perpendicular Magnetic Anisotropy in Ultrathin Ferrimagnetic NiCo$_2$O$_4$ Films,"The inverse spinel ferrimagnetic NiCo$_2$O$_4$ possesses high magnetic Curie
+temperature $T_C$, high spin polarization, and strain-tunable magnetic
+anisotropy. Understanding the thickness scaling limit of these intriguing
+magnetic properties in NiCo$_2$O$_4$ thin films is critical for their
+implementation in nanoscale spintronic applications. In this work, we report
+the unconventional magnetotransport properties of epitaxial (001) NiCo$_2$O$_4$
+films on MgAl$_2$O$_4$ substrates in the ultrathin limit. Anomalous Hall effect
+measurements reveal strong perpendicular magnetic anisotropy for films down to
+1.5 unit cell (1.2 nm), while $T_C$ for 3 unit cell and thicker films remains
+above 300 K. The sign change in the anomalous Hall conductivity ($\sigma_{xy}$)
+and its scaling relation with the longitudinal conductivity ($\sigma_{xx}$) can
+be attributed to the competing effects between impurity scattering and band
+intrinsic Berry curvature, with the latter vanishing upon the thickness driven
+metal-insulator transition. Our study reveals the critical role of film
+thickness in tuning the relative strength of charge correlation, Berry phase
+effect, spin orbit interaction, and impurity scattering, providing important
+material information for designing scalable epitaxial magnetic tunnel junctions
+and sensing devices using NiCo$_2$O$_4$.",2204.00133v2
+2022-03-29,A single Long Short-Term Memory network for enhancing the prediction of path-dependent plasticity with material heterogeneity and anisotropy,"This study presents the applicability of conventional deep recurrent neural
+networks (RNN) to predict path-dependent plasticity associated with material
+heterogeneity and anisotropy. Although the architecture of RNN possesses
+inductive biases toward information over time, it is still challenging to learn
+the path-dependent material behavior as a function of the loading path
+considering the change from elastic to elastoplastic regimes. Our attempt is to
+develop a simple machine-learning-based model that can replicate elastoplastic
+behaviors considering material heterogeneity and anisotropy. The basic
+Long-Short Term Memory Unit (LSTM) is adopted for the modeling of plasticity in
+the two-dimensional space by enhancing the inductive bias toward the past
+information through manipulating input variables. Our results find that a
+single LSTM based model can capture the J2 plasticity responses under both
+monotonic and arbitrary loading paths provided the material heterogeneity. The
+proposed neural network architecture is then used to model elastoplastic
+responses of a two-dimensional transversely anisotropic material associated
+with computational homogenization (FE2). It is also found that a single LSTM
+model can be used to accurately and effectively capture the path-dependent
+responses of heterogeneous and anisotropic microstructures under arbitrary
+mechanical loading conditions.",2204.01466v2
+2022-04-10,Giant magnetic in-plane anisotropy and competing instabilities in Na3Co2SbO6,"We report magnetometry data obtained on twin-free single crystals of
+Na3Co2SbO6, which is considered a candidate material for realizing the Kitaev
+honeycomb model for quantum spin liquids. Contrary to a common belief that such
+materials can be modeled with the symmetries of an ideal honeycomb lattice, our
+data reveal a pronounced two-fold symmetry and in-plane anisotropy of over
+200%, despite the honeycomb layer's tiny orthorhombic distortion of less than
+0.2%. We further use magnetic neutron diffraction to elucidate a rich variety
+of field-induced phases observed in the magnetometry. These phases manifest
+themselves in the paramagnetic state as diffuse scattering signals associated
+with competing ferro- and antiferromagnetic instabilities, consistent with a
+theory that also predicts a quantum spin liquid phase nearby. Our results call
+for theoretical understanding of the observed in-plane anisotropy, and render
+Na3Co2SbO6 a promising ground for finding exotic quantum phases by targeted
+external tuning.",2204.04593v2
+2022-04-12,The Annual Cycle in Scintillation Timescale of PMN J1726+0639,"We discovered rapid intra-day variability in radio source PMN J1726+0639 at
+GHz frequencies, during a survey to search for such variability with the
+Australia Telescope Compact Array. Follow-up observations were conducted over
+two years and revealed a clear, repeating annual cycle in the rate, or
+characteristic timescale, of variability, showing that the observed variations
+can be attributed to scintillations from interstellar plasma inhomogeneities.
+The strong annual cycle includes an apparent ""standstill"" in April and another
+in September. We fit kinematic models to the data, allowing for finite
+anisotropy in the scintillation pattern. The cycle implies a very high degree
+of anisotropy, with an axial ratio of at least 13:1, and the fit is consistent
+with a purely one-dimensional scintillation pattern. The position angle of the
+anisotropy, and the transverse velocity component are tightly constrained. The
+parameters are inconsistent with expectations from a previously proposed model
+of scattering associated with plasma filaments radially oriented around hot
+stars. We note that evidence for a foreground interstellar cloud causing
+anomalous Ca II absorption towards the nearby star Rasalhague ($\alpha$ Oph)
+has been previously reported, and we speculate that the interstellar
+scintillation of PMN 1726+0639 might be associated with this nearby cloud.",2204.05847v1
+2022-04-13,Long-term evolution of multimass rotating star clusters,"We investigate the long-term dynamical evolution of the internal kinematics
+of multimass rotating star clusters. We have performed a set of N-body
+simulations to follow the internal evolution of clusters with different degrees
+of initial rotation and have explored the evolution of the rotational velocity,
+the degree of energy equipartition, and anisotropy in the velocity
+distribution. Our simulations show that: 1) as the cluster evolves, the
+rotational velocity develops a dependence on the stellar mass with more massive
+stars characterised by a more rapid rotation and a peak in the rotation curve
+closer to the cluster centre than low-mass stars; 2) the degree of energy
+equipartition in the cluster's intermediate and outer regions depends on the
+component of the velocity dispersion measured; for more rapidly rotating
+clusters, the evolution towards energy equipartition is more rapid in the
+direction of the rotational velocity; 3) the anisotropy in the velocity
+distribution is stronger for massive stars; 4) both the degree of mass
+segregation and energy equipartition are characterised by spatial anisotropy;
+they have a dependence on both $R$ and $z$, correlated with the flattening in
+the spatial variation of the cluster's density and velocity dispersion, as
+shown by 2D maps of the mass segregation and energy equipartition on the
+($R$-$z$) meridional plane.",2204.06578v1
+2022-04-20,Varied magnetic phases in a van der Waals easy-plane antiferromagnet revealed by nitrogen-vacancy center microscopy,"Interest in van der Waals materials often stems from a desire to miniaturise
+existing technologies by exploiting their intrinsic layered structure to create
+near atomically-thin components that do not suffer from surface defects. One
+appealing property is easily-switchable yet robust magnetic order, a quality
+only sparsely demonstrated in the case of in-plane anisotropy. In this work, we
+use widefield nitrogen-vacancy (NV) center magnetic imaging to measure the
+properties of individual flakes of CuCrP$_2$S$_6$, a multiferroic van der Waals
+magnet known to exhibit weak easy-plane anisotropy in the bulk. We chart the
+crossover between in-plane ferromagnetism in thin flakes down to the trilayer,
+and the bulk behaviour dominated by a low-field spin-flop transition. Further,
+by exploiting the directional dependence of NV center magnetometry, we are able
+to observe an instance of a predominantly out-of-plane ferromagetic phase near
+zero field, in contradiction with expectation and previous experiments on the
+bulk material. We attribute this to the presence of surface anisotropies
+arising from the sample preparation process or exposure to the ambient
+environment, which is expected to have more general implications for a broader
+class of weakly anisotropic van der Waals magnets.",2204.09277v1
+2022-04-25,Reduced effective magnetization and damping by slowly-relaxing impurities in strained $γ$-$\mathrm{Fe_2O_3}$ thin films,"We study the static and dynamic magnetic properties of epitaxially strained
+$\gamma$-$\mathrm{Fe_2O_3}$ (maghemite) thin films grown via pulsed-laser
+deposition on MgO substrates by SQUID magnetometry and cryogenic broadband
+ferromagnetic resonance experiments. SQUID magnetometry measurements reveal
+hysteretic magnetization curves for magnetic fields applied both in- and out of
+the sample plane. From the magnetization dynamics of our thin films, we find a
+small negative effective magnetization in agreement with a strain induced
+perpendicular magnetic anisotropy. Moreover, we observe a non-linear evolution
+of the ferromagnetic resonance-linewidth as function of the microwave frequency
+and explain this finding with a model based on slowly relaxing impurities, the
+so-called slow relaxor model. By investigating the magnetization dynamics in
+our maghemite thin films as a function of frequency and temperature, we can
+isolate the temperature dependent contribution of the slowly relaxing
+impurities to the resonance linewidth and, in particular, observe a sign change
+in the effective magnetization. This finding provides evidence for a transition
+of the magnetic anisotropy from a perpendicular easy axis to an easy in-plane
+anisotropy for reduced temperatures.",2204.11498v1
+2022-04-28,Delocalization of dark and bright excitons in flat-band materials and the optical properties of V$_2$O$_5$,"The simplest picture of excitons in materials with atomic-like localization
+of electrons is that of Frenkel excitons, where electrons and holes stay close
+together, which is associated with a large binding energy. Here, using the
+example of the layered oxide V$_2$O$_5$ , we show how localized charge-transfer
+excitations combine to form excitons that also have a huge binding energy but,
+at the same time, a large electron-hole distance, and we explain this seemingly
+contradictory finding. The anisotropy of the exciton delocalization is
+determined by the local anisotropy of the structure, whereas the exciton
+extends orthogonally to the chains formed by the crystal structure. Moreover,
+we show that the bright exciton goes together with a dark exciton of even
+larger binding energy and more pronounced anisotropy. These findings are
+obtained by combining first principles many-body perturbation theory
+calculations, ellipsometry experiments, and tight binding modelling, leading to
+very good agreement and a consistent picture. Our explanation is general and
+can be extended to other materials.",2204.13580v2
+2022-05-08,Tuning the magnetic anisotropy and topological phase with electronic correlation in single-layer H-FeBr$_2$,"Electronic correlation can strongly influence the electronic properties of
+two-dimensional (2D) materials with open d- or f-orbitals. Herein, by taking
+single-layer (SL) H-FeBr$_2$ as a representative of the SL H-FeX$_2$ (X=Cl, Br,
+I) family, we investigated the electronic correlation effects in the magnetic
+anisotropy and electronic topology of such a system based on first-principles
+calculations with DFT+\textit{U} approach. Our result is that the magnetic
+anisotropy energy (MAE) of SL H-FeBr$_2$ shows a non-monotonic evolution
+behaviour with increasing electronic correlation strength, which is mainly due
+to the competition between different element-resolved MAEs of Fe and Br.
+Further investigations show that the evolution of element-resolved MAE arises
+from the variation of the spin-orbital coupling (SOC) interaction between
+different orbitals in each atom. Moreover, tuning the strength of the
+electronic correlation can drive the occurrence of band inversions, causing the
+system to undergoes multiple topological phase transitions, resulting in a
+quantum anomalous valley Hall (QAVH) effect. These exotic properties are
+universal for the SL H-FeX$_2$ (X = Cl, Br, I) family. Our work sheds light on
+the role of electronic correlation effects in tuning magnetic and electronic
+structures in the SL H-FeX$_2$ (X = Cl, Br, I) family, which could guide
+advances in the development of new spintronics and valleytronics devices based
+on these materials.",2205.03764v1
+2022-05-11,No nematicity at the onset temperature of the pseudogap phase in the cuprate superconductor YBCO,"Electronic nematicity is the spontaneous loss of rotational symmetry in a
+metal, without breaking translational symmetry. In the cuprate superconductors,
+there is experimental evidence for nematicity, but its origin remains unclear.
+Here we investigate the onset of nematicity in the transport of charge by means
+of electric and thermoelectric measurements in underdoped YBa$_{\rm 2}$Cu$_{\rm
+3}$O$_{\rm y}$, performed by passing the current (electrical or thermal) first
+along the $a$ axis then the $b$ axis of the orthorhombic structure in the same
+crystal, with a hole doping $p = 0.12$. Upon cooling, we observe no additional
+in-plane anisotropy -- beyond the background anisotropy due to the CuO chains
+-- in either the resistivity $\rho$ or the Seebeck coefficient $S$ as the
+temperature $T^{\star}$~for the onset of the pseudogap phase is crossed. We
+conclude that the pseudogap phase of cuprates is not nematic. However, at
+temperatures much lower than $T^{\star}$, a strong additional anisotropy is
+observed, most clearly in the Peltier coefficient $\alpha = S / \rho$. We
+interpret it as nematicity associated with the development of charge order.",2205.05233v2
+2022-05-12,Revisiting the Ulysses electron data with a triple fit of velocity distributions,"Given their uniqueness, the Ulysses data can still provide us with valuable
+new clues about the properties of plasma populations in the solar wind, and,
+especially, about their variations with heliographic coordinates. We revisit
+the electron data reported by by the SWOOPS instrument on-board of the Ulysses
+spacecraft between 1990 to early 2008. These observations reveal velocity
+distributions out of thermal equilibrium, with anisotropies (e.g., parallel
+drifts or/and different temperatures, parallel and perpendicular to the
+background magnetic field), and quasi-thermal and suprathermal populations with
+different properties. We apply a 2D nonlinear least square fitting procedure,
+using the Levenberg-Marquardt algorithm, to simultaneously fit the velocity
+electron data (up to a few keV) with a triple model combining three distinct
+populations: the more central quasi-thermal core and suprathermal halo, and a
+second suprathermal population consisting mainly of the electron strahl (or
+beaming population with a major field-aligned drift). The recently introduced
+$\kappa$-cookbook is used to describe each component with the following
+anisotropic distribution functions (recipes): Maxwellian, regularized kappa-,
+and generalized kappa-distributions. The temperature anisotropy quantified by
+the best fits is considered as a case study of the main parameters
+characterizing electron populations. By comparison to the core, both
+suprathermal populations exhibit higher temperature anisotropies, which
+slightly increase with the energy of electrons.",2205.05911v1
+2022-05-14,Strain effects on topological and valley properties of Janus monolayer $\mathrm{VSiGeN_4}$,"Strain is an effective method to tune the electronic properties of
+two-dimension (2D) materials, and can induce novel phase transition. Recently,
+2D $\mathrm{MA_2Z_4}$ family materials are of interest because of their
+emerging topological, magnetic and superconducting properties. Here, we
+investigate the impact of strain effects ($a/a_0$:0.96$\sim$1.04) on the
+physical properties of Janus monolayer $\mathrm{VSiGeN_4}$ as a derivative of
+$\mathrm{VSi_2N_4}$ or $\mathrm{VGe_2N_4}$, which possesses dynamical,
+mechanical and thermal stabilities. For out-of-plane magnetic anisotropy, with
+increasing strain, $\mathrm{VSiGeN_4}$ undergoes transition between ferrovalley
+semiconductor (FVS), half-valley-metal (HVM), valley-polarized quantum
+anomalous Hall insulator (VQAHI), HVM and FVS. These imply twice topological
+phase transitions, which are related with sign-reversible Berry curvature and
+band inversion between $d_{xy}$+$d_{x^2-y^2}$ and $d_{z^2}$ orbitals for K or
+-K valley. The band inversion also leads to transformation of valley splitting
+strength between valence and conduction bands. However, for in-plane magnetic
+anisotropy, no special quantum anomalous Hall (QAH) states and valley
+polarization exist within the considered strain range. The actual magnetic
+anisotropy energy (MAE) shows no special QAH and HVM states in monolayer
+$\mathrm{VSiGeN_4}$. Fortunately, these can be easily achieved by external
+magnetic field, which adjusts the easy magnetization axis of
+$\mathrm{VSiGeN_4}$ from in-plane one to out-of-plane one. Our findings shed
+light on how strain can be employed to engineer the electronic states of
+$\mathrm{VSiGeN_4}$, which may open new perspectives for multifunctional
+quantum devices in valleytronics and spintronics.",2205.07012v2
+2022-05-16,Induced gravitational waves from statistically anisotropic scalar perturbations,"Scalar-induced gravitational waves (SIGWs) are attracting growing attention
+for probing extremely short-scale scalar perturbations via gravitational wave
+measurements. In this paper, we investigate the SIGWs from statistically
+anisotropic scalar perturbations, which are motivated in inflationary scenarios
+in the presence of, e.g., a vector field. While the ensemble average of the
+SIGW energy spectrum is isotropic for the standard statistically isotropic
+scalar perturbations, the statistical anisotropy in the source introduces the
+multipole moments of the differential SIGW energy spectrum. We consider
+quadrupole anisotropy in the scalar power spectrum and show that the SIGW
+spectrum has anisotropies up to $\ell=4$. We present generic formulas of the
+multipole moments and then apply them to the delta-function-like and log-normal
+source spectra. We find analytic expressions for the former case and show that
+the infrared scalings of the multipole moments are the same as the isotropic
+SIGWs. Interestingly, the monopole has an additional local minimum in the
+high-$k$ tail, a key feature to distinguish from the isotropic SIGWs. The
+latter log-normal case is analytic for the narrow-peak source, and we perform
+the numerical calculation for the broad peak. As one expects, the multipole
+moments become broader with increasing source width. Our results are helpful to
+test the isotropy of primordial density perturbations at extremely small scales
+through SIGWs.",2205.07810v2
+2022-06-01,Possible unconventional order parameter in single crystals of SrPt$_3$P superconductor,"Anisotropic properties of single crystals of SrPt$_{3}$P were studied using
+London penetration depth and electrical resistivity measurements. The upper
+critical field, $H_{c2}(T)$, was determined from four-probe electrical
+resistivity measurements for three orthogonal directions of a magnetic field
+with respect to the crystal. The London penetration depth, $\lambda(T)$, was
+determined from the magnetic susceptibility of the Meissner-London state
+measured using a tunnel-diode resonator technique. Whereas $H_{c2}(T)$ and the
+normal-state $\rho(T)$ are practically identical for all three magnetic field
+orientations, the London penetration depth shows significant unidirectional
+anisotropy. The low-temperature $\lambda(T)$ is exponentially attenuated when a
+small excitation radiofrequency magnetic field, $H_{rf}$, is applied along the
+$c""-$direction, in which case screening currents flow in the $a""b""-$ plane,
+while for the other two orientations, $H_{rf}\parallel a""$ and $H_{rf}\parallel
+b""$, the London penetration depth shows a much weaker, $\lambda(T)\sim T^{2}$,
+variation. Such unusual and contrasting behavior of the two anisotropies,
+$\gamma_{H}\left(T\right)=H_{c2,ab}/H_{c2,c}=\xi_{ab}/\xi_{c}$ and
+$\gamma_{\lambda}\left(T\right)=\lambda_{c}/\lambda_{ab}$, imposes significant
+constraints on the possible order parameter. Although our measurements are
+insufficient to derive conclusively the superconducting gap anisotropy,
+qualitatively, order parameter with two point nodes and a modulation in the
+perpendicular direction is consistent with the experimental observations.",2206.00584v1
+2022-06-14,Quantitative assessment of perturbation theory-based lattice thermal conductivity models using quasi-continuum approximation,"The impact of dispersion relations, anisotropy, and Brillouin zone structure
+on intrinsic phonon scattering rates has been assessed within the harmonic
+approximation-perturbation theory approach for lattice dynamics. Anisotropic
+nonlinear elastic continuum has been considered with various levels of
+representation of phonon dispersion and Brillouin zone shape, and with
+Gr\""uneisen parameter used as an average measure of crystal anharmonicity. In
+addition, thermal conductivity prediction of different models for the treatment
+of the off-diagonal elements of phonon collision operator are compared. For a
+model system, argon, with a relatively high anisotropy ratio, the results show
+that accounting for anisotropy is critical for accurate determination of
+available phase space for 3-phonon scattering and scattering rates. Moreover,
+widely spread approximations such as isotropic continuum and Single Mode
+Relaxation Time are found unreliable, even for cubic systems. The success of
+these approximations is demonstrated to be a direct result of error
+cancellations. By benchmarking against our iterative solution of Boltzmann
+Transport Equation, which achieves excellent agreement with experimental
+thermal conductivity data for solid argon (2-80 K), we show the essential
+importance of considering coupling terms of phonon scattering kernel at phonon
+mode level, and not in a statistical average sense as, for example, Callaway
+model does. Moreover, our results manifest the role played by coherent phonon
+scattering near the melting temperature, in agreement with molecular dynamics
+findings, which serves as an evidence for the crossover between heat diffusion
+mediated by particle-like phonons (incoherent scattering) and wave-like heat
+propagation due to phonon coherent scattering. Furthermore, sensitivity of
+conductivity prediction to phonon spectrum is revealed to change over
+temperature.",2206.06634v1
+2022-07-05,"Prediction of High Curie Temperature, Large Magnetic Crystal Anisotropy in 2D Ferromagnetic Co$_2$Ge$_2$Te$_6$ Monolayer and Multilayer","The Co$_2$Ge$_2$Te$_6$ shows intrinsic ferromagnetic (FM) order, which
+origins from superexchange interaction between Co and Te atoms, with higher
+Curie temperature ($T_c$) of 161 K. Co$_2$Ge$_2$Te$_6$ monolayer (ML) is
+half-metal (HM), and spin-$\beta$ electron is a semiconductor with gap of 1.311
+eV. Co$_2$Ge$_2$Te$_6$ ML tends in-plane anisotropy (IPA), with magnetic
+anisotropy energy (MAE) of -10.2 meV/f.u.. Co$_2$Ge$_2$Te$_6$ ML shows good
+dynamical and thermal stability. Most interestingly, bilayers present
+ferromagnetic half-metallicity independent of the stacking orders. Notley, the
+multilayers ($N\ge 6$) present ferromagnetic HM, while the magnetoelectronic
+properties are related with the stacking patterns in thinner multilayers.
+Moreover, the magnetoelectronic properties are dependent on the stacking orders
+of bulk. The magnetic order with multilayers is determined by the super-super
+exchange and weak van der Waals (vdW) interaction. Co$_2$Ge$_2$Te$_6$ with
+intrinsic ferromagnetism, good stability of ferromagnetism and half-metallicity
+could help researchers to investigate its wide application in the spintronics.",2207.02024v1
+2022-07-15,The magnetic dynamics of NiPS$_3$,"Neutron spectroscopy measurements have been performed on single crystals of
+the antiferromagnetic van der Waals compound NiPS$_3$. Linear spin wave theory
+using a Heisenberg Hamiltonian with single-ion anisotropies has been applied to
+determine the magnetic exchange parameters and the nature of the anisotropy.
+The analysis reveals that NiPS$_3$ is less two-dimensional than its sister
+compounds, with a relatively large ferromagnetic exchange of $J^{\prime} =
+-0.3$ meV between the layered \emph{ab} planes. In-plane magnetic exchange
+interactions up to the third nearest-neighbour were required to fit the data.
+The nearest-neighbour exchange was ferromagnetic with $J_1 = -2.6$ meV, the
+second neighbour was antiferromagnetic and small with $J_2 = 0.2$ meV, and the
+dominant antiferromagnetic third neighbour exchange was $J_3 = 13.5$ meV. The
+anisotropy was shown to be largely XY-like with a small uniaxial component,
+leading to the appearance of two low-energy spin wave modes in the spin wave
+spectrum at the Brillouin zone centre. The analysis could reproduce the spin
+wave energies, however there are discrepancies with the calculated neutron
+intensities hinting at more exotic phenomena.",2207.07448v2
+2022-07-27,p x n-Type Transverse Thermoelectrics in a Type-II Weyl Semimetal TaIrTe4,"p x n-type materials refer to materials with a p-type Seebeck coefficient in
+one direction and a n-type coefficient in the orthogonal direction. This type
+of materials allows for a transverse thermoelectric response, which is highly
+desirable for energy applications. Here, we report the observation of p x
+n-type behavior in TaIrTe4, a type-II Weyl semimetal, with an in-plane
+thermopower anisotropy S$_{xx}$-S$_{yy}$ reaches a maximum value 40${\mu}$V/K
+at 200K. Intriguingly. we found that such a p x n-type behavior is absent in
+the similar compound NbIrTe4. The presence and absence of p x n-type behavior
+in these two materials are consistent with density functional theory
+calculations, which further predict that the thermopower anisotropy in both
+compounds can be enhanced up to 130${\mu}$V/K by electron doping. Such a strong
+thermopower anisotropy originates from the presence of both p-type and n-type
+carriers, each with high mobility in one direction. These results suggest that
+although type-II Weyl semimetal phase does not guarantee the existence of p x
+n-type behavior, its unique band structure provides the ingredient to engineer
+and optimize this phenomenon.",2207.13687v1
+2022-07-28,Model form uncertainty quantification of Reynolds-averaged Navier-Stokes modeling of flows over a SD7003 airfoil,"It is well known that the Boussinesq turbulent viscosity hypothesis can yield
+inaccurate predictions when complex f low features are involved, e.g.
+laminar-turbulent transition. The focus of the study is to explore the
+capability of a physics-based uncertainty quantification (UQ) approach to
+quantify the model-form uncertainty in Reynolds-averaged Naiver-Stokes (RANS)
+simulations of laminar-turbulent transitional flows over an Selig-Donovan (SD)
+7003 airfoil. This methodology perturbs the modeled Reynolds stress tensor in
+the momentum equations; perturbations are injected into the amplitude,
+eigenvalues and eigenvectors of the anisotropy Reynolds stress tensor undergone
+an eigen-decomposition. In this study, our analyses focus upon the amplitude
+perturbation. We observed a monotonic behavior of the magnitude of the
+predicted uncertainty bounds for different quantities of interest. High-order
+regressions based on the turbulence kinetic energy discrepancies are used to
+develop a novel switch marker function Mk to introduce perturbations in a
+non-uniform manner over different regions of the domain based upon prior
+knowledge of the limitations of the model. Importantly, the compound effect of
+Mk and eigenvalue perturbations show a synergy behavior, e.g., dramatically
+increased uncertainty bounds to account for the discrepancy in the RANS
+prediction; and the Mk function effectively avoids over-perturbation to the
+amplitude of the anisotropy Reynolds stress tensor. In this context, regression
+based amplitude perturbation of the anisotropy Reynolds stress tensor makes a
+new contribution to the RANS UQ methodology in the simulations of the airfoil
+transitional flows, which shows very encouraging results.",2207.14376v1
+2022-08-01,Hot spots along the Fermi contour of high-$T_c$ cuprates analyzed by $s$-$d$ exchange interaction,"We perform a thorough theoretical study of the electron properties of a
+generic CuO$_2$ plane in the framework of Shubin-Kondo-Zener $s$-$d$ exchange
+interaction that simultaneously describes the correlation between $T_c$ and the
+Cu4$s$ energy. To this end, we apply the Pokrovsky theory [J. Exp. Theor. Phys.
+13, 447-450 (1961)] for anisotropic gap BCS superconductors. It takes into
+account the thermodynamic fluctuations of the electric field in the dielectric
+direction perpendicular to the conducting layers. We microscopically derive a
+multiplicatively separable kernel able to describe the scattering rate in the
+momentum space, as well as the superconducting gap anisotropy within the BCS
+theory. These findings may be traced back to the fact that both the Fermi
+liquid and the BCS reductions lead to one and the same reduced Hamiltonian
+involving a separable interaction, such that a strong electron scattering
+corresponds to a strong superconducting gap and vice versa. Moreover, the
+superconducting gap and the scattering rate vanish simultaneously along the
+diagonals of the Brillouin zone. We would like to stress that our theoretical
+study reproduces the phenomenological analysis of other authors aiming at
+describing Angle Resolved Photoemission Spectroscopy measurements. Within
+standard approximations one and the same $s$-$d$ exchange Hamiltonian describes
+gap anisotropy of the superconducting phase and the anisotropy of scattering
+rate of charge carriers in the normal phase.",2208.00936v1
+2022-08-08,Study of Asymmetric Magnetization Reversal and Exchange Bias in FePt(L10)/FeCo/CoO/FeCo Magnetic Multilayer,"The effect of the saturation field on the magnetization reversal of
+FePt(L10)/FeCo/CoO/FeCo multilayer (ML) has been investigated to understand the
+origin of asymmetric magnetization reversal and its correlation with exchange
+bias (EB). In the ML structure, the bottom FeCo layer is coupled to the hard
+FePt(L10) layer, and the top FeCo layer is comparatively free due to the
+relatively more distance from it. The ML has been deposited under UHV
+conditions and characterized at each stage of growth using magneto-optical Kerr
+effect and x-ray reflectivity techniques. Magnetization reversal is further
+studied through domain imaging using the Kerr microscopy technique. The
+experimental findings reveal that ML exhibits asymmetrical magnetization
+reversal for a certain range of azimuthal angles for both 1.5kOe and 50kOe
+saturation fields; however, this angular range of asymmetry decreases with the
+increase in the saturation field. Furthermore, EB was absent at the low
+saturation field, whereas, EB, in addition to asymmetry, is observed at the
+large saturation field. The origin of asymmetry is attributed to
+non-collinearity between magnetic anisotropy axes of both FeCo layers. It
+results from the proximity effect through short-range Heisenberg exchange
+interaction via the CoO barrier layer. On the other hand, EB arises due to
+unidirectional anisotropy induced in the FePt layer due to the high saturation
+field. It is further proposed that asymmetry would disappear when
+unidirectional anisotropy is strong enough to align both the FeCo layers in the
+saturation direction leading to loss of the non-collinearity between them.",2208.04038v1
+2022-08-25,Biases to primordial non-Gaussianity measurements from CMB secondary anisotropies,"Our view of the last-scattering surface in the cosmic microwave background
+(CMB) is obscured by secondary anisotropies, sourced by scattering,
+extragalactic emission and gravitational processes between recombination and
+observation. Whilst it is established that non-Gaussianity from the correlation
+between the integrated-Sachs-Wolfe (ISW) effect and gravitational lensing can
+significantly bias primordial non-Gaussianity (PNG) searches, recent work by
+Hill (2018) has suggested that other combinations of secondary anisotropies can
+also produce significant biases. Building on that work, we use the WebSky and
+Sehgal et al.(2010) simulations to perform an extensive examination of possible
+biases to PNG measurements for the local, equilateral and orthogonal shapes.
+For a Planck-like CMB experiment, without foreground cleaning, we find
+significant biases from cosmic infrared background (CIB)-lensing and thermal
+Sunyaev-Zel'dovich (tSZ)-lensing bispectra for the local and orthogonal
+templates, and from CIB and tSZ bispectra for the equilateral template. For
+future experiments, such as the Simons Observatory, biases from correlations
+between the ISW effect and the tSZ and CIB will also become important. Finally
+we investigate whether foreground-cleaning techniques are able to suppress
+these biases sufficiently. We find that the majority of these biases are
+effectively suppressed by the internal-linear-combination method and the total
+bias to Planck-like and SO-like experiments is less than the $1\,\sigma$
+statistical error. However, the small total bias arises from the cancellation
+of several $1\,\sigma$ biases for Planck-like experiments and $2\,\sigma$
+biases for SO-like. As this cancellation is likely sensitive to the precise
+modelling, to ensure robustness against these biases explicit removal methods
+should be used, likely at the cost of decreased constraining power.",2208.12270v1
+2022-08-30,A study of Dipolar Signal in distant Quasars with various observables,"We study the signal of anisotropy in AGNs/quasars of CatWISE2020 catalogue
+using different observables. It has been reported earlier that this data shows
+a strong signal of dipole anisotropy in the source number counts. We test this
+claim using two independent data analysis procedures and find our number count
+dipole consistent with the earlier results. In addition to number counts, we
+test for the anisotropy signal in two other observables -- mean spectral index
+$\bar{\alpha}$ and mean flux density $\bar{B}$. We find a dipole signal of
+considerable strength both in the mean spectral index and the mean flux
+density. The dipole in mean flux density points towards the galactic center and
+becomes very weak after imposing a flux cut to remove sources with flux greater
+than 1 mJy. This can be attributed to the presence of some bright sources. The
+signal in mean spectral index, however, is relatively stable as a function of
+both flux and galactic cuts. The dipole in this observable points roughly
+opposite to the galactic center and hence most likely arises due to galactic
+bias. Hence, the signal in both the mean spectral index and mean flux density
+appears to be consistent with isotropy.",2208.14397v1
+2022-09-13,Investigating the role of partonic and hadronic dynamics in mass splitting of elliptic anisotropy in p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV,"The mass ordering of $v_{2}^{hadron}$ is regarded as one of the key
+signatures of collective behaviour in ultra relativistic heavy ion collisions.
+This observation has been found to be in compliance with the hydrodynamical
+response of a strongly interacting system to the initial spatial anisotropy.
+Flow co-efficients measured with identified particles in p-Pb/d-Au collisions
+have shown similar mass-splitting of $v_{2}^{hadron}$ indicating towards the
+presence of collective dynamics in small collision systems. Arguably, small
+size in the overlap geometry of such colliding systems may not be suitable for
+hydrodynamical treatment that demands an early thermalization. Studies based on
+a multi phase transport model suggests that elliptic or triangular anisotropy
+is primarily due to escape mechanism of partons rather than hydro like
+collectivity and mass ordering of $v_{2}^{hadron}$ can be generated from
+coalescence dynamics as implemented in string melting version of AMPT even when
+parton azimuthal directions are randomized. In this work, studies have been
+performed on p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV using AMPT model
+which has been found to explain the elliptic and traingular flow in such a
+system where escape mechanism is the dominant source of flow generation. We
+report that the mass splitting of $v_{2}^{hadron}$ can originate independently
+both at the partonic and hadronic level in the string melting version of the
+AMPT model.",2209.06166v1
+2022-09-16,Probing the Galactic halo with RR Lyrae stars $-$ III. The chemical and kinematic properties of the stellar halo,"Based on a large spectroscopic sample of $\sim$ 4,300 RR Lyrae stars with
+metallicity, systemic radial velocity and distance measurements, we present a
+detailed analysis of the chemical and kinematic properties of the Galactic
+halo. Using this sample, the metallicity distribution function (MDF) as a
+function of $r$ and the velocity anisotropy parameter $\beta$ profiles (for
+different metallicity populations) are derived for the stellar halo. Both the
+chemical and kinematic results suggest that the Galactic halo is composed of
+two distinct parts, the inner halo and outer halo. The cutoff radius ($\sim$ 30
+kpc) is similar to the previous break radius found in the density distribution
+of the stellar halo. We find that the inner part is dominated by a metal-rich
+population with extremely radial anisotropy ($\beta \sim 0.9$). These features
+are in accordance with those of ``{\it Gaia}-Enceladus-Sausage'' (GES) and we
+attribute this inner halo component as being dominantly composed of stars
+deposited from this ancient merged satellite. We find that GES probably has a
+slightly negative metallicity gradient. The metal-poor populations in the inner
+halo are characterized as a long-tail in MDF with an anisotropy of $\beta \sim
+0.5$, which is similar to that of the outer part. The MDF for the outer halo is
+very broad with several weak peaks and the value of $\beta$ is around 0.5 for
+all metallicities.",2209.07885v1
+2022-10-11,Wave-optics limit of the stochastic gravitational wave background,"The stochastic gravitational wave background (SGWB) is a rich resource of
+cosmological information, encoded both in its source statistics and
+anisotropies induced by propagation effects. We provide a theoretical
+description of it, without employing theoretical tools which rely on the
+geometric optics limit. Our formalism is based on the so-called {\it classical
+matter approximation} and it is able to capture wave-optics effects, such as
+interference and diffraction. We show that the interaction between the
+gravitational waves and the cosmic structures along the line-of-sight produce
+observable scalar and vector polarization modes, on top of modulating the
+tensorial ones. We build the two point correlation function describing the
+statistics of the SGWB, and introduce the intensity and gravitational Stokes
+parameters for all its components. In the case of an unpolarized, Gaussian and
+statistically homogeneous SGWB, we show that the interaction with matter
+modulates its intensity and does not generate a net difference between left-
+and right- helicity tensor and vector modes, as expected. We demonstrate that,
+in order to produce $Q_T$- and $U_T$- tensor polarization modes the background
+must posses an hexadecapole anisotropy, while a quandrupole anisotropy can
+source the vector $Q_V$- and $U_V$- Stokes parameters.",2210.05718v2
+2022-10-15,Azimuthal anisotropy of dijet events in PbPb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV,"The path-length dependent parton energy loss within the dense partonic medium
+created in lead-lead collisions at a nucleon-nucleon center-of-mass energy of
+$\sqrt{s_\mathrm{NN}}$ = 5.02 TeV is studied by determining the azimuthal
+anisotropies for dijets with high transverse momentum. The data were collected
+by the CMS experiment in 2018 and correspond to an integrated luminosity of
+1.69 nb$^{-1}$. For events containing back-to-back jets, correlations in
+relative azimuthal angle and pseudorapidity ($\eta$) between jets and hadrons,
+and between two hadrons, are constructed. The anisotropies are expressed as the
+Fourier expansion coefficients $v_n$, $n = $ 2-4 of these azimuthal
+distributions. The dijet $v_n$ values are extracted from long-range (1.5 $\lt$
+$\vert\Delta\eta\vert$ $\lt$ 2.5) components of these correlations, which
+suppresses the background contributions from jet fragmentation processes.
+Positive dijet $v_2$ values are observed which increase from central to more
+peripheral events, while the $v_3$ and $v_4$ values are consistent with zero
+within experimental uncertainties.",2210.08325v2
+2022-10-18,In-plane electronic anisotropy revealed by interlayer resistivity measurements on the iron-based superconductor parent compound CaFeAsF,"Both cuprates and iron-based superconductors demonstrate nematicity, defined
+as the spontaneous breaking of rotational symmetry in electron systems. The
+nematic state can play a role in the high-transition-temperature
+superconductivity of these compounds. However, the microscopic mechanism
+responsible for the transport anisotropy in iron-based compounds remains
+debatable. Here, we investigate the electronic anisotropy of CaFeAsF by
+measuring its interlayer resistivity under magnetic fields with varying field
+directions. Counterintuitively, the interlayer resistivity was larger in the
+longitudinal configuration ($B \parallel I \parallel c$) than in the transverse
+one ($B \perp I \parallel c$). The interlayer resistivity exhibited a so-called
+coherence peak under in-plane fields and was highly anisotropic with respect to
+the in-plane field direction. At $T$ = 4 K and $B$ = 14 T, the
+magnetoresistance $\Delta\rho/\rho_0$ was seven times larger in the $B
+\parallel b_o$ than in the $B \parallel a_o$ configuration. Our theoretical
+calculations of the conductivity based on the first-principles electronic band
+structure qualitatively reproduced the above observations but underestimated
+the magnitudes of the observed features. The proposed methodology can be a
+powerful tool for probing the nematic electronic state in various materials.",2210.09533v2
+2022-10-24,Studying the properties of compressible MHD turbulence by synchrotron fluctuation statistics,"We study the observable properties of compressible MHD turbulence covering
+different turbulence regimes, based on synthetic synchrotron observations
+arising from 3D MHD numerical simulations. Using the synchrotron emissivity and
+intensity, we first explore how the cosmic ray spectral indices affect the
+measurements of turbulence properties by employing normalized correlation
+functions. We then study how the anisotropy of synchrotron total and
+polarization intensities arising from three fundamental MHD modes vary with the
+viewing angle, i.e., the angle between the mean magnetic field and the line of
+sight. We employ the ratio of quadrupole moment to the monopole one (QM) for
+this purpose. Our numerical results demonstrate that: (1) the two-point
+correlation function of synchrotron statistics for the arbitrary cosmic ray
+spectral index is related to the special case of magnetic field index
+$\gamma=2$ in agreement with the analytical formulae provided by Lazarian \&
+Pogosyan (2012); (2) the anisotropy of synchrotron total and polarization
+intensities arising from Alfv\'en and slow modes increases with the increase of
+the viewing angle, while that of fast mode remains almost unchanged with the
+viewing angle; (3) the analytical formulae of synchrotron intensities for
+studying turbulence can be applied to describing statistics of polarization
+intensities, and the QM can be successfully used to recover turbulence
+anisotropy. This study validates Lazarian \& Pogosyan's analytical approach and
+opens a way to study turbulence from observations.",2210.13615v1
+2022-10-30,Synchrotron Firehose Instability,"We demonstrate using linear theory and particle-in-cell (PIC) simulations
+that a synchrotron-cooling collisionless plasma acquires pressure anisotropy
+and, if the plasma beta is sufficiently high, becomes unstable to the firehose
+instability, in a process that we dub the synchrotron firehose instability
+(SFHI). The SFHI channels free energy from the pressure anisotropy of the
+radiating, relativistic electrons (and/or positrons) into small-amplitude,
+kinetic-scale magnetic-field fluctuations, which pitch-angle scatter the
+particles and bring the plasma to a near-thermal state of marginal instability.
+The PIC simulations reveal a nonlinear cyclic evolution of firehose bursts
+interspersed by periods of stable cooling. We compare the SFHI for
+electron-positron and electron-ion plasmas. As a byproduct of the growing
+electron-firehose magnetic field fluctuations, magnetized ions gain a pressure
+anisotropy opposite to that of the electrons. If these ions are
+relativistically hot, we find that they also experience cooling due to
+collisionless thermal coupling with the electrons, which we argue is mediated
+by a secondary ion-cyclotron instability. We suggest that the SFHI may be
+activated in a number of astrophysical scenarios, such as within ejecta from
+black-hole accretion flows and relativistic jets, where the redistribution of
+energetic electrons from low to high pitch angles may cause transient bursts of
+radiation.",2210.16891v1
+2022-11-07,Anisotropic gravitational waves induced by hypermagnetic fields during the electroweak phase transition epoch,"We study the anisotropies of gravitational waves induced by weak
+hypermagnetic fields which are randomly distributed and oriented during the
+electroweak phase transition in the early universe. The theory setup of this
+study is the standard model plus a real singlet scalar field, which can produce
+the needed strongly first order electroweak phase transition. Then we
+investigate how the hypermagnetic fields can convert to magnetic fields and we
+compute the departure of energy difference between the symmetric phase and the
+broken phase when the magnetic fields are turned on. It is found that the
+presence of the hypermagnetic fields can increase the Euclidean action, thus
+can decrease nucleation temperature, which can lead to a supercool plasma. We
+point out that the hypermagnetic field can enhance the gravitational wave
+production from a first order electroweak phase transition and the
+inhomogeneity of primordial hypermagnetic field can lead to anisotropies of
+gravitational waves. By examining three well-motivated distribution of
+hypermagnetic fields, we calculate the corresponding angular power spectra of
+stochastic gravitational wave background and find they can be significantly
+larger than the contributions of the Sachs-Wolfe effects and integrated
+Sachs-Wolfe effects. Our results show that the anisotropies of gravitational
+wave could provide a novel probe to the primordial hypermagnetic field in the
+electroweak phase transition epoch.",2211.03368v2
+2022-11-18,Model-independent search for anisotropies in stochastic gravitational-wave backgrounds and application to LIGO-Virgo's first three observing Runs,"A stochastic gravitational-wave (GW) background consists of a large number of
+weak, independent and uncorrelated events of astrophysical or cosmological
+origin. The GW power on the sky is assumed to contain anisotropies on top of an
+isotropic component, i.e., the angular monopole. Complementary to the
+LIGO--Virgo--KAGRA (LVK) searches, we develop an efficient analysis pipeline to
+compute the maximum-likelihood anisotropic sky maps in stochastic backgrounds
+directly in the sky pixel domain using data folded over one sidereal day. We
+invert the full pixel-pixel correlation matrix in map-making of the GW sky, up
+to an optimal eigenmode cutoff decided systematically using simulations. In
+addition to modeled mapping, we implement a model-independent method to probe
+spectral shapes of stochastic backgrounds. Using data from LIGO--Virgo's first
+three observing runs, we obtain upper limits on anisotropies as well as the
+isotropic monopole as a limiting case, consistent with the LVK results. We also
+set constraints on the spectral shape of the stochastic background using this
+novel model-independent method.",2211.10010v3
+2022-11-30,CMB temperature trispectrum from accreting primordial black holes,"It is known that Primordial Black Holes (PBHs) can leave an imprint on Cosmic
+Microwave Background (CMB) anisotropy power spectra, due to their
+accretion-powered injection of energy into the recombining plasma. Here we
+study a qualitatively new CMB observable sourced by accreting PBHs: the
+temperature trispectrum or connected 4-point function. This non-Gaussian
+signature is due to the strong spatial modulation of the PBH accretion
+luminosity, thus ionization perturbations, by large-scale supersonic relative
+velocities between PBHs and the accreted baryons. We first derive a
+factorizable quadratic transfer function for free-electron fraction
+inhomogeneities induced by accreting PBHs. We then compute the perturbation to
+the CMB temperature anisotropy due to a general modification of recombination,
+and apply our results to accreting PBHs. We calculate a new contribution to the
+temperature power spectrum due to the spatial fluctuations of the ionization
+perturbation induced by accreting PBHs, going beyond past studies which only
+accounted for its homogeneous part. While these contributions are formally
+comparable, we find the new part to be subdominant, due to the poor correlation
+of the perturbed temperature field with the standard CMB anisotropy. For the
+first time, we compute the temperature trispectrum due to accreting PBHs. This
+trispectrum is weakly correlated with the local-type primordial non-Gaussianity
+trispectrum, hence constraints on the latter do not lead to competitive bounds
+on accreting PBHs. We also forecast Planck's sensitivity to the temperature
+trispectrum sourced by accreting PBHs. Excitingly, we find it to be more
+sensitive to PBHs under $\sim 10^3 M_{\odot}$ than current temperature-only
+power spectrum constraints. This result motivates our future work extending
+this study to temperature and polarization trispectra induced by
+inhomogeneously-accreting PBHs.",2212.00075v1
+2022-12-07,Effects of surfactants on bubble-induced turbulence,"We use experiments to explore the effect of surfactants on bubble-induced
+turbulence (BIT) at different scales, considering how the bubbles affect the
+flow kinetic energy, anisotropy and extreme events. To this end,
+high-resolution Particle Shadow Velocimetry measurements are carried out in a
+bubble column in which the flow is generated by bubble swarms rising in water
+for two different bubble diameters ($3$ mm $\&$ $4$ mm) and moderate gas volume
+fractions ($0.5\%\sim1.3\%$). To contaminate the flow, different amounts of
+1-Pentanol were added to the flow, leading to different bubble shapes and
+surface boundary conditions. The results reveal that with increasing surfactant
+concentration, the BIT generated increases in strength, even though bubbles of
+a given size rise more slowly with surfactants. We also find that the level of
+anisotropy in the flow is enhanced with increasing surfactant concentration for
+bubbles of the same size, and that for the same surfactant concentration,
+smaller bubbles generate stronger anisotropy in the flow. Concerning the
+intermittency quantified by the normalized probability density functions of the
+fluid velocity increments, our results indicate that extreme values in the
+velocity increments become more probable with decreasing surfactant
+concentration for cases with smaller bubbles and low gas void fraction, while
+the effect of the surfactant is much weaker for cases with larger bubble and
+higher void fractions.",2212.03620v1
+2022-12-08,Detection of Dipole Modulation in CMB Temperature Anisotropy Maps from WMAP and Planck using Artificial Intelligence,"Breakdown of rotational invariance of the primordial power spectrum manifests
+in the statistical anisotropy of the observed Cosmic Microwave Background (CMB)
+radiation. Hemispherical power asymmetry in the CMB may be caused due to a
+dipolar modulation, indicating the presence of a preferred direction.
+Appropriately re-scaled local variance maps of the CMB temperature anisotropy
+data effectively encapsulate this dipolar pattern. As a first-of-its-kind
+method, we train Artificial Neural Networks (ANNs) with such local variances as
+input features to distinguish statistically isotropic CMB maps from dipole
+modulated ones. Our trained ANNs are able to predict components of the
+amplitude times the unit vector of the preferred direction for mixed sets of
+modulated and unmodulated maps, with goodness of fit ($R^2$) scores $>0.97$ for
+full sky, and $>0.96$ for partial sky coverage. On all observed
+foreground-cleaned CMB maps, the ANNs detect the dipolar modulation signal with
+overall consistent values of amplitudes and directions. This detection is
+significant at $97.21\%-99.38\%$ C.L. for all full sky maps, and at
+$98.34\%-100\%$ C.L. for all partial sky maps. Robustness of the signal holds
+across full and partial skies, various foreground cleaning methods, inpainting
+algorithms, instruments and all the different periods of observation for Planck
+and WMAP satellites. The significant and robust detection of the signal, in
+addition to the consistency of values of amplitude and directions, as found
+independent of any pre-existing methods, further mitigates the criticisms of
+look-elsewhere effects and a posteriori inferences for the preferred dipole
+direction in the CMB.",2212.04438v2
+2022-12-19,Anisotropic correlation functions as tracers of central galaxy alignments in simulations,"Motivated by observational results, we use IllustrisTNG hydrodynamical
+numerical simulations to study the alignment of the central galaxies in groups
+with the surrounding structures. This approach allows us to analyse galaxy and
+group properties not available in observations. To perform this analysis, we
+use a modified version of the two-point cross-correlation function and a
+measure of the angle between the semi-major axes of the central galaxies and
+the larger structures. Overall, our results reproduce observational ones, as we
+find large-scale anisotropy, which is dominated by the red central galaxies. In
+addition, the latter is noticeably more aligned with their group than the blue
+ones. In contrast to the observations, we find a strong dependence of the
+anisotropy on the central galaxy with mass, probably associated with the
+inability of observational methods to determine them. This result allows us to
+link the alignment to the process of halo assembly and the well-known
+dependence of halo anisotropy on mass. When we include the dark matter
+distribution in our analysis, we conclude that the galaxy alignment found in
+simulations (and observations) can be explained by a combination of physical
+processes at different scales: the central galaxy aligns with the dark matter
+halo it inhabits, and this, in turn, aligns with the surrounding structures at
+large scales.",2212.09781v2
+2022-12-21,Adiabatic preparation of fractional Chern insulators from an effective thin-torus limit,"We explore the quasi one-dimensional (thin torus, or TT) limit of fractional
+Chern insulators (FCIs) as a starting point for their adiabatic preparation in
+quantum simulators. Our approach is based on tuning the hopping amplitude in
+one direction as an experimentally amenable knob to dynamically change the
+effective aspect ratio of the system. Similar to the TT limit of fractional
+quantum Hall (FQH) systems in the continuum, we find that the hopping-induced
+TT limit adiabatically connects the FCI state to a trivial charge density wave
+(CDW) ground state. This adiabatic path may be harnessed for state preparation
+schemes relying on the initialization of a CDW state followed by the adiabatic
+decrease of a hopping anisotropy. Our findings are based on the calculation of
+the excitation gap in a number of FCI models, both on a lattice and consisting
+of coupled wires. By analytical calculation of the gap in the limit of strongly
+anisotropic hopping, we show that its scaling is compatible with the
+preparation of large size FCIs for sufficiently large hopping anisotropy. Our
+numerical simulations in the framework of exact diagonalization explore the
+full anisotropy range to corroborate these results.",2212.11294v2
+2022-12-20,Anisotropic electron transport in the nuclear pasta phase,"The presence of nuclear pasta is expected to modify the transport properties
+in the mantle of neutron stars. The non-spherical geometry of the pasta nuclear
+clusters leads to anisotropies in the collision frequencies, impacting the
+thermal and electrical conductivity. We derive analytical expressions for the
+anisotropic collision frequencies using the Boltzmann equation in the
+relaxation time approximation. The average parallel, perpendicular and Hall
+electrical conductivities are computed in the high-temperature regime above
+crustal melting, considering incoherent elastic electron-pasta scattering and
+randomly oriented pasta structures. Numerical values are obtained at different
+densities and temperatures by using the IUFSU parametrization of the non-linear
+Walecka model to determine the crustal structure. We find that the anisotropy
+of the collision frequencies grows with the length of the pasta structures and,
+independently of the magnetic field, the presence of rod and slab phases
+decreases the conductivity by more than one order of magnitude. Our numerical
+results indicate that, even if the pasta structures might survive above the
+crustal melting point, no strong anisotropies are to be expected in the
+conduction properties in this temperature regime, even in the presence of a
+very high magnetic field.",2212.11817v3
+2022-12-30,Selection rules for ultrafast laser excitation and detection of spin correlations dynamics in a cubic antiferromagnet,"Exchange interactions determine the correlations between microscopic spins in
+magnetic materials. Probing the dynamics of these spin correlations on
+ultrashort length and time scales is, however rather challenging, since it
+requires simultaneously high spatial and high temporal resolution. Recent
+experimental demonstrations of laser-driven two-magnon modes - zone-edge
+excitations in antiferromagnets governed by exchange coupling - posed questions
+about the microscopic nature of the observed spin dynamics, the mechanism
+underlying its excitation, and their macroscopic manifestation enabling
+detection. Here, on the basis of a simple microscopic model, we derive the
+selection rules for cubic systems that describe the polarization of pump and
+probe pulses required to excite and detect dynamics of nearest-neighbor spin
+correlations, and can be employed to isolate such dynamics from other magnetic
+excitations and magneto-optical effects. We show that laser-driven spin
+correlations contribute to optical anisotropy of the antiferromagnet even in
+the absence of spin-orbit coupling. In addition, we highlight the role of
+subleading anisotropy in the spin system and demonstrate that the dynamics of
+the antiferromagnetic order parameter occurs only in next-to-leading order,
+determined by the smallness of the magnetic anisotropy as compared to the
+isotropic exchange interactions in the system. We expect that our results will
+stimulate and support further studies of magnetic correlations on the shortest
+length and time scale.",2212.14698v2
+2023-01-07,"Single crystal growths and magnetic properties of hexagonal polar semimetals RAuGe (R = Y, Gd-Tm, and Lu)","We study structural and magnetic properties of rare-earth based semimetals
+RAuGe (R = Y, Gd-Tm, and Lu) using flux-grown single crystals. These compounds
+belong to the noncentrosymmetric polar space group P63mc. We confirm the
+systematic structural evolution at room temperature as a function of ionic
+radius of rare earths to clarify the isopointal crossover between two polar
+structures: three-dimensional LiGaGe-type and quasi-two-dimensional
+NdPtSb-type. Magnetism shows a characteristic anisotropy in reasonable
+agreement with the crystal electric field (CEF) theory; the easy-plane-type
+anisotropy for R = Tb and Dy turns into the Ising-type anisotropy for R = Er
+and Tm. We evaluate the CEF parameters based on the Stevens operators to
+reasonably reproduce the temperature dependence of magnetic susceptibilities
+and specific heat for RAuGe (R = Tb-Tm). The estimated energy scale of the
+Ising gap (~ 11 meV) in TmAuGe is consistent with an excitation observed in an
+inelastic neutron scattering experiment. These findings suggest an opportunity
+for interplay between conduction electrons and nontrivial spin structures in
+the family of magnetic polar semimetals RAuGe.",2301.02794v1
+2023-01-09,"Radial pulsations, moment of inertia and tidal deformability of dark energy stars","We construct dark energy stars with Chaplygin-type equation of state (EoS) in
+the presence of anisotropic pressure within the framework of Einstein gravity.
+From the classification established by Iyer et al. [Class. Quantum Grav. 2, 219
+(1985)], we discuss the possible existence of isotropic dark energy stars as
+compact objects. However, there is the possibility of constructing
+ultra-compact stars for sufficiently large anisotropies. We investigate the
+stellar stability against radial oscillations, and we also determine the moment
+of inertia and tidal deformability of these stars. We find that the usual
+static criterion for radial stability $dM/d\rho_c >0$ still holds for dark
+energy stars since the squared frequency of the fundamental pulsation mode
+vanishes at the critical central density corresponding to the maximum-mass
+configuration. The dependence of the tidal Love number on the anisotropy
+parameter $\alpha$ is also examined. We show that the surface gravitational
+redshift, moment of inertia and dimensionless tidal deformability undergo
+significant changes due to anisotropic pressure, primarily in the high-mass
+region. Furthermore, in light of the detection of gravitational waves GW190814,
+we explore the possibility of describing the secondary component of such event
+as a stable dark energy star in the presence of anisotropy.",2301.03504v1
+2023-01-12,Debiasing Standard Siren Inference of the Hubble Constant with Marginal Neural Ratio Estimation,"Gravitational wave (GW) standard sirens may resolve the Hubble tension,
+provided that standard siren inference of $H_0$ is free from systematic biases.
+However, standard sirens from binary neutron star (BNS) mergers suffer from two
+sources of systematic bias, one arising from the anisotropy of GW emission, and
+the other from the anisotropy of electromagnetic (EM) emission from the
+kilonova. For an observed sample of BNS mergers, the traditional Bayesian
+approach to debiasing involves the direct computation of the detection
+likelihood. This is infeasible for large samples of detected BNS merger due to
+the high dimensionality of the parameter space governing merger detection. In
+this study, we bypass this computation by fitting the Hubble constant to
+forward simulations of the observed GW and EM data under a simulation-based
+inference (SBI) framework using marginal neural ratio estimation. A key
+innovation of our method is the inclusion of BNS mergers which were only
+detected in GW, which allows for estimation of the bias introduced by EM
+anisotropy. Our method corrects for $\sim$90$\%$ of the bias in the inferred
+value of $H_0$ when telescope follow-up observations of BNS mergers have
+extensive tiling of the merger localization region, using known telescope
+sensitivities and assuming a model of kilonova emission. Our SBI-based method
+thus enables a debiased inference of the Hubble constant of BNS mergers,
+including both mergers with detected EM counterparts and those without.",2301.05241v1
+2023-01-22,Responses of quark-antiquark interaction and heavy quark dynamics to magnetic field,"We study how a magnetic field induced by colliding nuclei influences both
+heavy quark (HQ) potential and HQ momentum diffusion coefficients beyond the
+lowest Landau level approximation. By means of real-time hard thermal loop
+resummed technique combined with dimension two gluon condensate, the effective
+gluon propagator describing both perturbative and nonperturbative QCD nature at
+finite temperature and magnetic field are obtained. We find that HQ momentum
+diffusion coefficients in magnetized QCD medium become anisotropic, and with
+increasing temperature, the higher Landau levels become significant, which
+leads to the reduction of the anisotropic ratio ($>$ 1) and even overturn the
+behavior ($<$ 1) at high temperature. The nonperturbative (perturbative)
+contribution of HQ momentum diffusion coefficient in the low (high) temperature
+is dominant. And the anisotropy feature of the real part of the potential is
+essentially encoded in angular dependent Coulomb coupling and string tension.
+Whereas, the imaginary part of the potential from quark-loop in this work
+displays a significant anisotropy even though using the angular-independent
+Coulomb coupling and string tension. Furthermore, we study the magnetic
+response of viscous quark matter, which is manifested in the non-equilibrium
+distribution function of (anti-)quark by solving Boltzmann equation within the
+relaxation time approximation. We find the anisotropy ratio is almost
+insensitive to the magnetized bulk viscosity, although HQ momentum diffusion
+coefficient and HQ potential itself have visible changes.",2301.09110v1
+2023-02-01,First measurements of periodicities and anisotropies of cosmic ray flux observed with a water-Cherenkov detector at the Marambio Antarctic base,"A new water-Cherenkov radiation detector, located at the Argentine Marambio
+Antarctic Base (64.24S-56.62W), has been monitoring the variability of galactic
+cosmic ray (GCR) flux since 2019. One of the main aims is to provide
+experimental data necessary to study interplanetary transport of GCRs during
+transient events at different space/time scales. In this paper we present the
+detector and analyze observations made during one full year. After the analysis
+and correction of the GCR flux variability due to the atmospheric conditions
+(pressure and temperature), a study of the periodicities is performed in order
+to analyze modulations due to heliospheric phenomena. We can observe two
+periods: (a) 1 day, associated with the Earth's rotation combined with the
+spatial anisotropy of the GCR flux; and (b) $\sim$ 30 days due to solar impact
+of stable solar structures combined with the rotation of the Sun. From a
+superposed epoch analysis, and considering the geomagnetic effects, the mean
+diurnal amplitude is $\sim$ 0.08% and the maximum flux is observed in $\sim$ 15
+hr local time (LT) direction in the interplanetary space. In such a way, we
+determine the capability of Neurus to observe anisotropies and other
+interplanetary modulations on the GCR flux arriving at the Earth.",2302.00322v1
+2023-02-05,The role of spatial curvature in constraining the Universe anisotropies across a Big Bounce,"We study the implementation of Polymer Quantum Mechanics (PQM) to a system
+decomposed into a quasi-classical background and a small quantum subsystem,
+according to the original Vilenkin proposal. We develop the whole formalism in
+the momentum representation that is the only viable in the continuum limit of
+the polymer paradigm and we generalize the fundamental equations of the
+original Vilenkin analysis in the considered context. Then, we provide a
+Minisuperspace application of the theory, first considering a Bianchi I
+cosmology and then extending the analysis to a Bianchi IX model in the limit of
+small anisotropies. In both these cases, the quasi-classical background is
+identified with an isotropic bouncing Universe whereas the small quantum
+subsystem contains the anisotropic degrees of freedom. When the Big Bounce
+scenario is considered, we obtain that in the Bianchi I model the anisotropies
+standard deviation is regular at $t=0$ but still increases indefinitely,
+whereas in the presence of the harmonic Bianchi IX potential such same quantity
+is bounded and oscillate around a constant value. As a consequence, we
+demonstrate that the picture of a semiclassical isotropic Bounce can be
+extended to more general cosmological settings if the spatial curvature becomes
+relevant when the anisotropic degrees of freedom are still small quantum
+variables.",2302.02469v2
+2023-02-24,Dielectric tunability of magnetic properties in orthorhombic ferromagnetic monolayer CrSBr,"Monolayer CrSBr is a recently discovered semiconducting spin-3/2 ferromagnet
+with a Curie temperature around 146 K. Unlike many other known two-dimensional
+(2D) magnets, CrSBr has an orthorhombic lattice, giving rise, for instance, to
+spatial anisotropy of the magnetic excitations within the 2D plane. Theoretical
+description of CrSBr within a spin Hamiltonian approach turns out to be
+nontrivial due to the triaxial magnetic anisotropy as well as due to magnetic
+dipolar interactions, comparable to spin-orbit effects in CrSBr. Here, we
+employ a Green's function formalism combined with first-principles calculations
+to systematically study the magnetic properties of monolayer CrSBr in different
+regimes of surrounding dielectric screening. We find that the magnetic
+anisotropy and thermodynamical properties of CrSBr depend significantly on the
+Coulomb interaction and its external screening. In the free-standing limit, the
+system turns out to be close to an easy-plane magnet, whose long-range ordering
+is partially suppressed. On the contrary, in the regime of large external
+screening, monolayer CrSBr behaves like an easy-axis ferromagnet with more
+stable magnetic ordering. Despite being relatively large, the magnetic dipolar
+interactions have only little effect on the magnetic properties. Our findings
+suggests that 2D CrSBr is suitable platform for studying the effects of
+substrate screening on magnetic ordering in low dimensions.",2302.12672v1
+2023-03-08,First-principles study of enhancement of perpendicular magnetic anisotropy obtained by inserting an ultrathin LiF layer at an Fe/MgO interface,"Perpendicular magnetic anisotropy (PMA) is a key property of magnetoresistive
+random access memory (MRAM). To increase areal density of MRAM it is important
+to find a way to enhance the PMA. Recently a strong enhancement of the PMA by
+inserting an ultrathin LiF layer at an Fe/MgO interface was reported [T. Nozaki
+et al., NPG Asia Materials (2022) 14: 5]. To understand the origin of the
+observed enhancement of the PMA we perform first-principles calculations of
+magetocrystalline anisotropy energy (MAE) of the following four kind of
+multilayer structures: Fe/MgO, Fe/LiF/MgO, Fe/FeO/MgO, and Fe/FeF/LiF/MgO. We
+find that the MAEs of the Fe/LiF/MgO and the Fe/FeF/LiF/MgO structures are
+almost the same as that of the Fe/MgO structure, while the MAE of the
+Fe/FeO/MgO structure is less than a half of that of the Fe/MgO structure. The
+results show that the major origin of the enhancement of the PMA obtained by
+inserting an ultrathin LiF layer at an Fe/MgO interface is the suppression of
+the mixing of Fe and O atoms at the interface. We also find that the in-plane
+Fe-F coupling gives a positive contribution to the MAE while the in-plane Fe-O
+coupling gives a negative contribution. The results are useful for designing of
+high-PMA materials.",2303.04382v1
+2023-03-08,Effect of massive graviton on dark energy star structure,"The presence of massive gravitons in the field of massive gravity is
+considered as an important factor in investigating the structure of compact
+objects. Hence, we are encouraged to study the dark energy star structure in
+the Vegh's massive gravity. We consider that the equation of state governing
+the inner spacetime of the star is the extended Chaplygin gas, and then using
+this equation of state, we numerically solve the Tolman-Oppenheimer-Volkoff
+(TOV) equation in massive gravity. In the following, assuming different values
+of free parameters defined in massive gravity, we calculate the properties of
+dark energy star such as radial pressure, transverse pressure, anisotropy
+parameter, and other characteristics. Then, after obtaining the maximum mass
+and its corresponding radius, we compute redshift and compactness. The obtained
+results show that for this model of dark energy star, the maximum mass and its
+corresponding radius depend on the massive gravity's free parameters and
+anisotropy parameter. These results are consistent with the observational data,
+and cover the lower mass gap. We also demonstrate that all energy conditions
+are satisfied for this model, and in the presence of anisotropy, the dark
+energy star is potentially unstable.",2303.04813v2
+2023-03-10,Anisotropic LRS-BI Universe with $f(Q)$ gravity theory,"The possible anisotropic nature in the early phases of the Universe is one of
+the interesting aspects of study in cosmology. We investigate the evolution of
+the Universe in terms of few cosmological parameters considering an anisotropic
+locally rotationally symmetric (LRS) Bianchi type-I spacetime (LRS-BI) under
+the $f(Q)$ gravity of symmetric teleparallel theory equivalent to the GR
+(STEGR). In this study we consider two $f(Q)$ gravity models, viz., $f(Q) =
+-\,(Q+2\Lambda)$, a simple model with the cosmological constant $\Lambda$ and
+the power law model, $f(Q) = -\, \alpha Q^n$ with two constant parameters
+$\alpha$ and $n$. Considering a proportionality relation between the
+directional Hubble parameters with a proportionality constant parameter
+$\lambda$ we find a significant contribution of the anisotropic factor in the
+evolution of the early Universe for both models. The power law model shows the
+more dominating effect of anisotropy in comparison to the simple model
+depending on model parameters, especially on the parameter $n$. The power law
+model also shows some possible effects of anisotropy on the Universe's
+evolution in the near future. In addition, both models confirm that the
+anisotropy does not obtain any appreciable signature in the current stage of
+the Universe. From our analysis we also set rough constraints on our model
+parameters as $0.5 \le \lambda \le 1.25$, $0.75 \le \alpha \le 1.5$ and $0.95
+\le n \le 1.05$.",2303.05905v1
+2023-03-26,The effect of the magnetically dead layer on the magnetization and the magnetic anisotropy of the dextran coated magnetite nanoparticles,"We present a study on the magnetic behavior of dextran-coated magnetite
+nanoparticles (DM NPs) with sizes between 3 and 19 nm, synthesized by
+hydrothermal-assisted co-precipitation method. The decrease of saturation
+magnetization ($M_s$) with decreasing particle size has been modeled by
+assuming the existence of a spin-disordered layer at the particle surface,
+which is magnetically dead. Based on this core-shell model and taking into
+account the weight contribution of the non-magnetic coating layer (dextran) to
+the whole magnetization, the dead layer thickness ($t$) and saturation
+magnetization $M_s$ of the magnetic cores in our samples were estimated to be
+$t = 6.8~\mathrm{\AA}$ and $M_s = 98.8~\mathrm{emu/g}$, respectively. The data
+of $M_s$ were analyzed using a law of approach to saturation, indicating an
+increase in effective magnetic anisotropy ($K_{eff}$) with decreasing particle
+size as expected from the increased surface/volume ratio in small MNPs. The
+obtained $K_{eff}$ values were successfully modeled by including an extra
+contribution of dipolar interactions due to the formation of chain-like
+clusters of MNPs. The surface magnetic anisotropy ($K_s$) was estimated to be
+about $K_s = 1.04\times10^5~\mathrm{J/m^3}$. Our method provides a simple and
+accurate way to obtain the $M_s$ core values in surface-disordered MNPs, a
+relevant parameter required for magnetic modeling in many applications.",2303.14654v1
+2023-03-27,Terahertz probing of anisotropic conductivity and morphology of CuMnAs epitaxial thin films,"Antiferromagnetic CuMnAs thin films have attracted attention since the
+discovery of the manipulation of their magnetic structure via electrical,
+optical, and terahertz pulses of electric fields, enabling convenient
+approaches to the switching between magnetoresistive states of the film for the
+information storage. However, the magnetic structure and, thus, the efficiency
+of the manipulation can be affected by the film morphology and growth defects.
+In this study, we investigate the properties of CuMnAs thin films by probing
+the defect-related uniaxial anisotropy of electric conductivity by contact-free
+terahertz transmission spectroscopy. We show that the terahertz measurements
+conveniently detect the conductivity anisotropy, that are consistent with
+conventional DC Hall-bar measurements. Moreover, the terahertz technique allows
+for considerably finer determination of anisotropy axes and it is less
+sensitive to the local film degradation. Thanks to the averaging over a large
+detection area, the THz probing also allows for an analysis of strongly
+non-uniform thin films. Using scanning near-field terahertz and electron
+microscopies, we relate the observed anisotropic conductivity of CuMnAs to the
+elongation and orientation of growth defects, which influence the local
+microscopic conductivity. We also demonstrate control over the morphology of
+defects by using vicinal substrates.",2303.15268v1
+2023-03-30,Data-driven approach for modeling Reynolds stress tensor with invariance preservation,"The present study represents a data-driven turbulent model with Galilean
+invariance preservation based on machine learning algorithm. The fully
+connected neural network (FCNN) and tensor basis neural network (TBNN) [Ling et
+al. (2016)] are established. The models are trained based on five kinds of flow
+cases with Reynolds Averaged Navier-Stokes (RANS) and high-fidelity data. The
+mappings between two invariant sets, mean strain rate tensor and mean rotation
+rate tensor as well as additional consideration of invariants of turbulent
+kinetic energy gradients, and the Reynolds stress anisotropy tensor are
+trained. The prediction of the Reynolds stress anisotropy tensor is treated as
+user's defined RANS turbulent model with a modified turbulent kinetic energy
+transport equation. The results show that both FCNN and TBNN models can provide
+more accurate predictions of the anisotropy tensor and turbulent state in
+square duct flow and periodic flow cases compared to the RANS model. The
+machine learning based turbulent model with turbulent kinetic energy gradient
+related invariants can improve the prediction precision compared with only mean
+strain rate tensor and mean rotation rate tensor based models. The TBNN model
+is able to predict a better flow velocity profile compared with FCNN model due
+to a prior physical knowledge.",2303.17178v2
+2023-04-03,Nonrelativistic and nonmagnetic control of terahertz charge currents via electrical anisotropy in RuO2 and IrO2,"Precise and ultrafast control over photo-induced charge currents across
+nanoscale interfaces could lead to important applications in energy harvesting,
+ultrafast electronics, and coherent terahertz sources. Recent studies have
+shown that several relativistic mechanisms, including inverse spin-Hall effect,
+inverse Rashba-Edelstein effect and inverse spin-orbit-torque effect, can
+convert longitudinally injected spin-polarized currents from magnetic materials
+to transverse charge currents, thereby harnessing these currents for terahertz
+generation. However, these mechanisms typically require external magnetic
+fields and suffer from low spin-polarization rates and low efficiencies of
+relativistic spin-to-charge conversion. In this work, we present a novel
+nonrelativistic and nonmagnetic mechanism that directly utilizes the
+photo-excited high-density charge currents across the interface. We demonstrate
+that the electrical anisotropy of conductive oxides RuO2 and IrO2 can
+effectively deflect injected charge currents to the transverse direction,
+resulting in efficient and broadband terahertz radiation. Importantly, this new
+mechanism has the potential to offer much higher conversion efficiency compared
+to previous methods, as conductive materials with large electrical anisotropy
+are readily available, whereas further increasing the spin-Hall angle of
+heavy-metal materials would be challenging. Our new findings offer exciting
+possibilities for directly utilizing these photo-excited high-density currents
+across metallic interfaces for ultrafast electronics and terahertz
+spectroscopy.",2304.00692v1
+2023-04-03,Correlated order at the tipping point in the kagome metal CsV$_3$Sb$_5$,"Spontaneously broken symmetries are at the heart of many phenomena of quantum
+matter and physics more generally. However, determining the exact symmetries
+broken can be challenging due to imperfections such as strain, in particular
+when multiple electronic orders form complex interactions. This is exemplified
+by charge order in some kagome systems, which are speculated to show nematicity
+and flux order from orbital currents. We fabricated highly symmetric samples of
+a member of this family, CsV$_3$Sb$_5$, and measured their transport
+properties. We find the absence of measurable anisotropy at any temperature in
+the unperturbed material, however, a striking in-plane transport anisotropy
+appears when either weak magnetic fields or strains are present. A symmetry
+analysis indicates that a perpendicular magnetic field can indeed lead to
+in-plane anisotropy by inducing a flux order coexisting with more conventional
+bond order. Our results provide a unifying picture for the controversial charge
+order in kagome metals and highlight the need for microscopic materials control
+in the identification of broken symmetries.",2304.00972v1
+2023-04-05,Effective model for superconductivity in magic-angle graphene,"We carry out large-scale quantum Monte Carlo simulations of a candidate field
+theory for the onset of superconductivity in magic-angle twisted bilayer
+graphene. The correlated insulating state at charge neutrality spontaneously
+breaks U(1) Moir\'e valley symmetry. Owing to the topological nature of the
+bands, skyrmion defects of the order parameter carry charge $2e$ and condense
+upon doping. In our calculations we encode the U(1) symmetry by an internal
+degree of freedom such that it is not broken upon lattice regularization.
+Furthermore, the skyrmion carries the same charge. The nature of the
+doping-induced phase transitions depends on the strength of the easy-plane
+anisotropy that reduces the SU(2) valley symmetry to U(1) $\times \mathbb{Z}_2
+$. For large anisotropy, we observe two distinct transitions separated by phase
+coexistence. While the insulator to superconducting transition is of mean-field
+character, the U(1) transition is consistent with three-dimensional XY
+criticality. Hence, the coupling between the gapless charge excitations of the
+superconducting phase and the XY order parameter is irrelevant. At small
+anisotropy, we observe a first-order transition characterized by phase
+separation.",2304.02428v2
+2023-04-25,Role of effective mass anisotropy in realizing a hybrid nodal-line fermion state,"Understanding the role of lattice geometry in shaping topological states and
+their properties is of fundamental importance to condensed matter and device
+physics. Here we demonstrate how an anisotropic crystal lattice drives a
+topological hybrid nodal line in transition metal tetraphosphides $Tm$P$_4$
+($Tm$ = Transition metal). $Tm$P$_4$ constitutes a unique class of black
+phosphorus materials formed by intercalating transition metal ions between the
+phosphorus layers without destroying the characteristic anisotropic band
+structure of the black phosphorous. Based on the first-principles calculations
+and $k \cdot p$ theory, we show that $Tm$P$_4$ harbor a single hybrid nodal
+line formed between oppositely-oriented anisotropic $Tm~d$ and P states
+unhinged from the high-symmetry planes. The nodal line consists of both type-I
+and type-II nodal band crossings whose nature and location are determined by
+the effective-mass anisotropies of the intersecting bands. We further discuss a
+possible topological phase transition to exemplify the formation of the hybrid
+nodal line state in $Tm$P$_4$. Our results offer a comprehensive study for
+understanding the interplay between structural motifs-driven mass anisotropies
+and topology in anisotropic lattice materials to realize hybrid semimetal
+states.",2304.13086v3
+2023-04-28,"Noncollinear magnetic order, in-plane anisotropy, and magnetoelectric coupling in a pyroelectric honeycomb antiferromagnet Ni$_{2}$Mo$_{3}$O$_{8}$","Ni$_{2}$Mo$_{3}$O$_{8}$ is a pyroelectric honeycomb antiferromagnet
+exhibiting peculiar changes of its electric polarization at magnetic
+transitions. Ni$_{2}$Mo$_{3}$O$_{8}$ stands out from the isostructural magnetic
+compounds, showing an anomalously low magnetic transition temperature and
+unique magnetic anisotropy. We determine the magnetic structure of
+Ni$_{2}$Mo$_{3}$O$_{8}$ utilizing high-resolution powder and single-crystal
+neutron diffraction. A noncollinear stripy antiferromagnetic order is found in
+the honeycomb planes. The magnetic space group is \textit{P$_C$na}2$_1$. The
+in-plane magnetic connection is of the stripy type both for the $ab$-plane and
+the $c$-axis spin components. This is a simpler connection than the one
+proposed previously. The ferromagnetic interlayer order of the $c$-axis spin
+components in our model is also distinct. The magnetic anisotropy of
+Ni$_{2}$Mo$_{3}$O$_{8}$ is characterized by orientation-dependent magnetic
+susceptibility measurements on a single crystal, consistent with neutron
+diffraction analysis. The local magnetoelectric tensor analysis using our
+magnetic models provides new insights into its magnetoelectric coupling and
+polarization. Thus, our results deliver essential information for understanding
+both the unusual magnetoelectric properties of Ni$_{2}$Mo$_{3}$O$_{8}$ and the
+prospects for observation of exotic nonreciprocal, Hall, and magnonic effects
+characteristic to this compound family.",2304.14641v2
+2023-04-29,"Structural, electronic, and magnetic properties of CrTe2","Two-dimensional chromium ditelluride (CrTe2) is a promising ferromagnetic
+layered material that exhibits long-range ferromagnetic ordering in the
+monolayer limit. The formation energies of the different possible structural
+phases (1T, 1H, 2H) calculated from density functional theory (DFT) show that
+the 1T phase is the ground state, and the energetic transition barriers between
+the phases, calculated by the nudged elastic band method, are large, on the
+order of 0.5 eV. The self-consistent Hubbard $U$ correction parameters are
+calculated for all the phases of CrTe$_2$. The calculated magnetic moment of
+1T-CrTe$_2$ with $\geq 2$ layers lies in the plane, whereas the magnetic moment
+of a monolayer is out-of-plane. Band filling and tensile bi-axial strain cause
+the magnetic moment of a monolayer to switch from out-of-plane to in-plane, and
+compressive bi-axial strain in a bilayer causes the magnetic moment to switch
+from in-plane to out-of-plane. The magnetic anisotropy is shown to originate
+from the large spin orbit coupling (SOC) of the Te atoms and the anisotropy of
+the exchange coupling constants $J_{xy}$ and $J_z$ in an XXZ type Hamiltonian.
+Renormalized spin wave theory using experimental values for the magnetic
+anisotropy energy and Curie temperatures provides a range of values for the
+nearest neighbor exchange coupling.",2305.00168v1
+2023-05-27,A 3D Numerical Study of Anisotropies in Supernova Remnants,"We develop a suite of 3D hydrodynamic models of supernova remnants (SNRs)
+expanding against the circumstellar medium (CSM). We study the Rayleigh-Taylor
+Instability (RTI) forming at the expansion interface by calculating an angular
+power spectrum for each of these models. The power spectra of young SNRs is
+seen to exhibit a dominant angular mode, which is a diagnostic of their ejecta
+density profile as found by previous studies. The steep scaling of power at
+smaller modes and the time evolution of the spectra is indicative of absence of
+a turbulent cascade. Instead, as the time evolution of the spectra suggests,
+they may be governed by an angular mode dependent net growth rate. We also
+study the impact of anisotropies in the ejecta as well as in the CSM on the
+power spectra of velocity and density. We confirm that perturbations in the
+density field (whether imposed on the ejecta or the CSM) do not influence the
+anisotropy of the remnant significantly unless they have a very large amplitude
+and form large-scale coherent structures. In any case, these clumps can only
+affect structures on large angular scales. The power spectra on small angular
+scales is completely independent of the initial clumpiness and only governed by
+the growth and saturation of the Rayleigh-Taylor instability.",2305.17324v2
+2023-06-05,Random sequential adsorption of aligned rectangles with two discrete orientations: Finite-size scaling effects,"We study saturated packings produced according to random sequential
+adsorption (RSA) protocol built of identical rectangles deposited on a flat,
+continuous plane. An aspect ratio of rectangles is defined as the
+length-to-width ratio, $f=l/w$. The rectangles have a fixed unit area (i.e., $l
+\times w=1$), and therefore, their shape is defined by the value of $f$
+($l=\sqrt{f}$ and $w=1/\sqrt{f}$). The rectangles are allowed to align either
+vertically or horizontally with equal probability. The particles are deposited
+on a flat square substrate of side length $L$ (measured in units of particle
+length, $L \in [20, 1000]$) and periodic boundary conditions are applied along
+both directions. The finite-size scaling effects are characterized by a scaled
+anisotropy defined as $\alpha = l/L = \sqrt{f}/L$. We showed that the
+properties of such packings strongly depend on the value of aspect ratio $f$
+and the most significant scaling effects are observed for relatively long
+rectangles when $l\ge L/2$ (i.e. $\alpha \ge 0.5$). It is especially visible
+for the mean packing fraction as a function of the scaled anisotropy $\alpha$.
+The kinetics of packing growth for low to moderate rectangle anisotropy is to
+be governed by $\ln t/t$ law, where $t$ is proportional to the number of RSA
+iterations, which is the same as in the case of RSA of parallel squares. We
+also analyzed global orientational ordering in such packings and properties of
+domains consisting of a set of neighboring rectangles of the same orientation,
+and the probability that such domain forms a percolation.",2306.03259v1
+2023-06-14,Interfering Josephson diode effect and magnetochiral anisotropy in Ta2Pd3Te5 asymmetric edge interferometer,"Edge states of topological systems have attracted great interest due to their
+robustness and linear dispersions. Here a superconducting-proximitized edge
+interferometer is engineered on a second-order topological insulator Ta2Pd3Te5
+with asymmetric edges to realize the interfering Josephson diode effect (JDE),
+which hosts many advantages, such as the high efficiency as much as 73% at tiny
+applied field 8.4 mT an ultra-low switching power around picowatt, and a giant
+interfering magnetochiral anisotropy with a coefficient $\gamma$ = 1.2 $\times
+10^9$ T$^{-1}$A$^{-1}$ - three orders of magnitude larger than the reported
+record. As an important element to induce such JDE, the second-order harmonic
+in the current-phase relation is also experimentally confirmed by half Shapiro
+steps. This edge interferometer offers a novel and effective method to enhance
+the overall performance of JDE and magnetochiral anisotropy, and boosts great
+potential application for future superconducting quantum devices.",2306.08478v1
+2023-07-17,Nematic spin correlations pervading the phase diagram of FeSe$_{1-x}$S$_{x}$,"We use resonant inelastic X-ray scattering (RIXS) at the Fe-L$_3$ edge to
+study the spin excitations of uniaxial-strained and unstrained
+FeSe$_{1-x}$S$_{x}$ ($0\leq x\leq0.21$) samples. The measurements on unstrained
+samples reveal dispersive spin excitations in all doping levels, which show
+only minor doping dependence in energy dispersion, lifetime, and intensity,
+indicating that high-energy spin excitations are only marginally affected by
+sulfur doping. RIXS measurements on uniaxial-strained samples reveal that the
+high-energy spin-excitation anisotropy observed previously in FeSe is also
+present in the doping range $0< x\leq0.21$ of FeSe$_{1-x}$S$_{x}$. The
+spin-excitation anisotropy persists to a high temperature up to $T>200$ K in
+$x=0.18$ and reaches a maximum around the nematic quantum critical doping
+($x_c\approx0.17$). Since the spin-excitation anisotropy directly reflects the
+existence of nematic spin correlations, our results indicate that high-energy
+nematic spin correlations pervade the regime of nematicity in the phase diagram
+and are enhanced by the nematic quantum criticality. These results emphasize
+the essential role of spin fluctuations in driving electronic nematicity and
+open the door for uniaxial strain tuning of spin excitations in quantum
+materials hosting strong magnetoelastic coupling and electronic nematicity.",2307.08181v1
+2023-08-01,Self-consistent dynamical models with a finite extent -- III. Truncated power-law spheres,"Fully analytical dynamical models usually have an infinite extent, while real
+star clusters, galaxies, and dark matter haloes have a finite extent. The
+standard method for generating dynamical models with a finite extent consists
+of taking a model with an infinite extent and applying a truncation in binding
+energy. This method, however, cannot be used to generate models with a pre-set
+analytical mass density profile. We investigate the self-consistency and
+dynamical properties of a family of power-law spheres with a general tangential
+Cuddeford (TC) orbital structure. By varying the density power-law slope
+$\gamma$ and the central anisotropy $\beta_0$, these models cover a wide
+parameter space in density and anisotropy profiles. We explicitly calculate the
+phase-space distribution function for various parameter combinations, and
+interpret our results in terms of the energy distribution of bound orbits. We
+find that truncated power-law spheres can be supported by a TC orbital
+structure if and only if $\gamma \geqslant 2\beta_0$, which means that the
+central density slope-anisotropy inequality is both a sufficient and a
+necessary condition for this family. We provide closed expressions for
+structural and dynamical properties such as the radial and tangential velocity
+dispersion profiles, which can be compared against more complex numerical
+modelling results. This work significantly adds to the available suite of
+self-consistent dynamical models with a finite extent and an analytical
+description.",2308.00366v1
+2023-08-16,Multiple antiferromagnetic phases and magnetic anisotropy in exfoliated CrBr$_3$ multilayers,"In twisted two-dimensional (2D) magnets, the stacking dependence of the
+magnetic exchange interaction can lead to regions of ferromagnetic and
+antiferromagnetic interlayer order, separated by non-collinear, skyrmion-like
+spin textures. Recent experimental searches for these textures have focused on
+CrI$_3$, known to exhibit either ferromagnetic or antiferromagnetic interlayer
+order, depending on layer stacking. However, the very strong uniaxial
+anisotropy of CrI$_3$ disfavors smooth non-collinear phases in twisted
+bilayers. Here, we report the experimental observation of three distinct
+magnetic phases -- one ferromagnetic and two antiferromagnetic -- in exfoliated
+CrBr$_3$ multilayers, and reveal that the uniaxial anisotropy is significantly
+smaller than in CrI$_3$. These results are obtained by magnetoconductance
+measurements on CrBr$_3$ tunnel barriers and Raman spectroscopy, in conjunction
+with density functional theory calculations, which enable us to identify the
+stackings responsible for the different interlayer magnetic couplings. The
+detection of all locally stable magnetic states predicted to exist in CrBr$_3$
+and the excellent agreement found between theory and experiments, provide
+complete information on the stacking-dependent interlayer exchange energy and
+establish twisted bilayer CrBr$_3$ as an ideal system to deterministically
+create non-collinear magnetic phases.",2308.08355v1
+2023-09-02,An Isotropic Discretization with Semi-implicit Approach for Phase Field Model of Alloy Solidification,"Quantitative phase field models have been extensively used to study the
+solidification behavior of alloys under different conditions. However, a
+longstanding challenge of phase field models is the directional bias caused by
+the discretization-induced lattice effects. In particular, widely used
+discretization methods may introduce significant spurious anisotropy for
+simulations of polycrystalline solidification. In this paper, we demonstrate a
+feasible 2D discretization strategy utilizing a hexagonal mesh to reduce the
+lattice-induced anisotropy of the phase field model. The leading differential
+terms of the 2D discretization methods are analyzed by using known methods in
+Fourier space. Using Taylor expansion of discrete Fourier Transform up to sixth
+order, we found that the proposed discretization strategy is more accurate and
+isotropic than other methods, including the isotropic discretization recently
+proposed by Ji et al.[1]. Additionally, the proposed 2D discretization method
+can be easily incorporated into a semi-implicit algorithm to solve phase field
+equations, thereby greatly reducing time step constraints and improving
+computational efficiency compared to explicit approaches. To prove the accuracy
+and efficiency of the proposed isotropic discretization with semi-implicit
+algorithm, 2D simulations of alloy solidification with different discretization
+schemes were performed and compared. We show that the proposed discretization
+using a hexagonal mesh can drastically reduce grid-induced anisotropy compared
+to conventional methods.",2309.00836v1
+2023-09-29,"Magnetism, transport and atomic structure of amorphous binary YxCo1-x alloys","Sputtered thin films of binary YxCo1-x with 0 < x < 0.54 and thickness 15 nm
+are investigated to help understand the ferromagnetism of cobalt in amorphous
+rare-earth cobalt alloys. The magnetic moment per cobalt falls to zero at x0 =
+0.50, where the appearance of magnetism is marked by a para-process with a
+dimensionless susceptibility of up to 0.015. All films are magnetically soft,
+with densities that fall between those of crystalline Y-Co intermetallic
+compounds and the density of a relaxed 10,000-atom binary random close-packed
+model of hard spheres with an Y:Co volume ratio of 3:1, where the packing
+fractions for all films lies in a narrow range around 0.633 and Co is
+coordinated by 3.2 Co and 3.2 Y atoms at x = 0.5. All films with x < 0.4
+exhibit in-plane shape anisotropy that is about six times as great as an
+intrinsic perpendicular component. Average cobalt spin and orbital moments
+obtained by X-ray magnetic circular dichroism were 1.31 and 0.32 Bohr
+magnetons, respectively for amorphous Y0.25Co0.75. Strong local anisotropy is
+associated with the large cobalt orbital moment, but there is little influence
+of anisotropy on the ferromagnetic order because of exchange averaging. The
+Hall effect and magnetoresistance are modelled in terms of effective uniform
+rotation of the magnetization, with spontaneous and band contributions.
+Amorphous YxCo1-x is contrasted with amorphous YxFe1-x, which exhibits random
+noncollinear magnetic order that is very sensitive to the film density.",2309.16996v1
+2023-10-04,Numerical modeling of hydrogel scaffold anisotropy during extrusion-based 3D printing for tissue engineering,"Extrusion-based 3D printing is a recent and widely used tissue engineering
+tool that provides precise 3D control of bioinks to create organ-size
+biomaterial-based objects composed of hierarchically organized cellularized
+scaffolds. The internal organization of scaffold constituents should mimic the
+structural anisotropy of targeted tissue to stimulate proliferative cellular
+behavior during 3D cell culture. Both the choice of polymers constituting the
+bioink and the topological properties during the extrusion process greatly
+influence the structural anisotropy and cellular response of tissue engineering
+constructs. The bioink used in our study was a hydrogel made of three
+constituents: fibrinogen, alginate and gelatin. These components provide
+biocompatibility, printability and conservation of 3D shape after printing. The
+topological properties in flowing polymers are dictated by macromolecule
+conformation i.e. their orientation and degree of stretch. In this study, we
+used the micro-macro approach to describe the orientation state of hydrogel
+macromolecules during the extrusion process, offering a two-scale description
+of fluid behavior. The goal of our study was to use the Fokker-Planck equation,
+which describes the evolution of probability distribution function over time,
+to represent the real state of the constituent population in the representative
+elementary volume within a hydrogel during extrusion-based 3D printing. Our
+data suggest that for a tubular nozzle syringe, constituent orientation is
+driven by a high shear rate, which overcomes the fluid rheological behavior.
+Also, the interaction coefficient, which represents the microscopic interaction
+between fluid particles overcomes hydrogel behavior for constituent orientation
+in the prediction model.",2310.02734v2
+2023-10-11,Constraining Bianchi-I universe with Pantheon SNIa data,"We study the Bianchi-I cosmological model motivated by signals of statistical
+isotropy violation seen in cosmic microwave background (CMB) observations and
+others. To that end, we consider various kinds of anisotropic matter that
+source anisotropy in our model, specifically cosmic strings, magnetic fields,
+domain walls and Lorentz violation generated magnetic fields. These anisotropic
+matter sources, taking one at a time, are studied for their co-evolution with
+standard model (isotropic) sources viz., dust-like (dark/normal) matter and
+dark energy modelled as cosmological constant. We constrain the Hubble
+parameter, density fractions of anisotropic matter, isotropic cold dark matter
+(CDM) and dark energy ($\Lambda$) in a Bianchi-I universe with planar symmetry
+i.e., with a global ellipsoidal geometry, and try to find signatures of a
+cosmic preferred axis if any. Pantheon Type Ia Supernova (SNIa) data is used in
+our study to obtain constraints on cosmological parameters of this model. In
+our analysis, we found a cosmic axis of anisotropy using SN1e data.
+Interestingly this preferred axis lies in the same direction, broadly, as some
+other cosmic anisotropy axes reported in the literature such as the CMB
+hemispherical power asymmetry, etc., with some of anisotropic sources
+considered. We also found a non-zero evidence for cosmic shear and eccentricity
+for our universe with those sources. To be more conclusive, we require more
+SNIa host galaxy data for tighter constraints on distance and absolute
+magnitude calibration which we hope will be available from the future JWST
+observations and other surveys.",2310.07661v1
+2023-10-11,On the anisotropic distribution of clusters in the local Universe,"In his 2021 lecture to the Canadian Association of Physicists Congress,
+P.J.E. Peebles pointed out that the brightest extra-galactic radio sources tend
+to be aligned with the plane of the de Vaucouleur Local Supercluster up to
+redshifts of $z=0.02$ ($d_{\rm MW}\approx 85~\rm{Mpc}$). He then asked whether
+such an alignment of clusters is anomalous in the standard $\Lambda$CDM
+framework. In this letter, we employ an alternative, absolute orientation
+agnostic, measure of the anisotropy based on the inertia tensor axis ratio of
+these brightest sources and use a large cosmological simulation from the
+FLAMINGO suite to measure how common such an alignment of structures is. We
+find that only 3.5% of randomly selected regions display an anisotropy of their
+clusters more extreme than the one found in the local Universe's radio data.
+This sets the region around the Milky Way as a $1.85\sigma$ outlier. Varying
+the selection parameters of the objects in the catalogue, we find that the
+clusters in the local Universe are never more than $2\sigma$ away from the
+simulations' prediction for the same selection. We thus conclude that the
+reported anisotropy, whilst note-worthy, is not in tension with the
+$\Lambda$CDM paradigm.",2310.07866v2
+2023-10-23,A multiple time scale approach for anisotropic inertial wave turbulence,"Wave turbulence is the study of the long-time statistical behaviour of
+equations describing a set of weakly non-linear interacting waves. Such a
+theory, which has a natural asymptotic closure, allows us to probe the nature
+of turbulence more deeply than the exact Kolmogorov laws by rigorously proving
+the direction of the cascade and the existence of an inertial range, predicting
+stationary spectra for conserved quantities, or evaluating the Kolmogorov
+constant. An emblematic example is given by fast rotating fluids for which a
+wave turbulence theory has been derived by Galtier (2003). This work involves
+nontrivial analytical developments for a problem that is anisotropic by nature.
+We propose here a new path for the derivation of the kinetic equation by using
+the anisotropy at the beginning of the analysis. We show that the helicity
+basis is not necessary to obtain the wave amplitude equation for the canonical
+variables that involve a combination of poloidal and toroidal fields. The
+multiple time scale method adapted to this anisotropic problem is then used to
+derive the kinetic equation which is the same as the original work when
+anisotropy is eventually taken into account. This result proves the
+commutativity between asymptotic closure and anisotropy. In addition, the
+multiple time scale method informs us that the kinetic equation can be derived
+without imposing restrictions on the probability distribution of the wave
+amplitude such as quasi-Gaussianity, or on the phase such as random phase
+approximation which naturally occurs dynamically.",2310.14640v1
+2023-10-26,Honing cross-correlation tools for inference on ultra-high-energy cosmic-ray composition,"The chemical composition of the highest-energy cosmic rays, namely the atomic
+number $Z$ of rays with energies $E\gg1~\text{EeV}$, remains to date largely
+unknown. Some information on the composition can be inferred from the
+deflections that charged ultra-high-energy cosmic rays experience while they
+traverse intervening magnetic fields. Indeed, such deflections distort and
+suppress the original anisotropy in the cosmic rays arrival directions; thus, a
+measure of the anisotropy is also a measurement of the deflections, which in
+turn informs us on the chemical composition. In this work, we show that, by
+quantifying ultra-high-energy cosmic ray anisotropies through the angular,
+harmonic cross-correlation between cosmic rays and galaxies, we are able to
+exclude iron fractions $f_{\rm Fe}\leq{\cal O}(10\%)$ on a fiducial hydrogen
+map at $2\sigma$ level, and even smaller fractions in the reverse case of
+hydrogen on an iron map, going below $f_{\rm H}\lesssim10\%$ when we mask the
+Galactic Centre up to latitudes of $40\,\text{deg}$. This is an improvement of
+a factor of a few compared to our previous method, and is mostly ascribable to
+a new test statistics which is sensitive to each harmonic multipole
+individually. Our method can be applied to real data as an independent test of
+the recent claim that current cosmic-ray data can not be reproduced by any
+existing model of the Galactic magnetic field, as well as an additional handle
+to compare any realistic, competing, data-driven composition models.",2310.17699v2
+2023-11-17,In plane quantification of in vivo muscle elastic anisotropy factor by steered ultrasound pushing beams,"Skeletal muscles are organized into distinct layers and exhibit anisotropic
+characteristics across various scales. Assessing the arrangement of skeletal
+muscles may provide valuable biomarkers for diagnosing muscle related
+pathologies and evaluating the efficacy of clinical interventions. In this
+study, we propose a novel ultrafast ultrasound sequence constituted of steered
+pushing beams was proposed for ultrasound elastography applications in
+transverse isotropic muscle. Based on the propagation of the shear wave
+vertical mode, it is possible to fit the experimental results to retrieve in
+the same imaging plane, the shear modulus parallel to fibers as well as the
+elastic anisotropy factor. The technique was demonstrated in vitro in phantoms
+and ex vivo in fusiform beef muscles. At last, the technique was applied in
+vivo on fusiform muscles (biceps braachi) and mono-penate muscles
+(gastrocnemius medialis) during stretching and contraction. This novel sequence
+provides access to new structural and mechanical biomarkers of muscle tissue,
+including the elastic anisotropy factor, within the same imaging plane.
+Additionally, it enables the investigation of multiples parameters during
+muscle active and passive length changes.",2311.10620v1
+2023-11-27,Spin order dependent skyrmion stabilization in MnFeCoGe hexagonal magnets,"Topological magnetic skyrmions in centrosymmetric systems exhibit a higher
+degrees of freedom in their helicity, hence possess a great potential in the
+advanced spintronics including skyrmion based quantum computation. However, the
+centrosymmetric magnets also display non-topological trivial bubbles along with
+the topological skyrmions. Hence it is utmost priority to investigate the
+impact of different magnetic ground states and their underlying interactions on
+the stabilization of magnetic skyrmions in cetrosymmetric magnets. Here, we
+present a combined theoretical and experimental study on the role of
+non-collinear magnetic ground state on the skyrmion stabilization in a series
+of exchange frustrated non-collinear ferromagnetic system MnFe1-xCoxGe. With
+the help of neutron diffraction (ND) and Lorentz transmission electron
+microscopy (LTEM) studies, we show that hexagonal skyrmions lattice emerges as
+a stable field driven state only when the underlying magnetic ground state is
+collinear with easy-axis anisotropy. In contrast, non-topological type-II
+bubbles are found to be stable state in the case of non-collinear magnetic
+ordering with partial in-plane anisotropy. Furthermore, we also find that the
+skyrmions transform to the non-topological bubbles when the system undergoes a
+spin reorientation transition from the easy-axis to easy-cone ferromagnetic
+phase. Our results categorically establish the significant role of in-plane
+magnetic moment/anisotropy that hinders the stability of skyrmion both in the
+case of collinear and non-collinear magnets. Thus, the present study offers a
+wide range of opportunities to manipulate the stability of dipolar skyrmions by
+changing the intrinsic characteristics of the materials.",2311.15823v1
+2023-12-04,Optical anisotropy and nonlinearity in deep ultraviolet fluorooxoborates,"Optical anisotropy and nonlinearity are two tantalizingly important and
+enticing properties of an optical crystal. Combining these two features will
+have a miraculous effect. The up conversion can extend solid state laser
+sources to the ultraviolet and deep ultraviolet (DUV) ranges through harmonic
+generation and for down conversion needed for quantum information technology,
+but only a few suitable materials are known as the medium because of the
+combination of properties that are required. These include suitable band gaps,
+moderate optical anisotropy for phase matching and strong nonlinear optical
+(NLO) response. Fluorooxoborates are a new ideal platform for this effect in
+DUV. Here we demonstrate that fluorooxoborate is the optimal framework for DUV
+NLO material and show that the significance of the incorporation of fluorine in
+borates. The NLO performance of fluorooxoborates is strongly improved in terms
+of local crystal structure and distribution of electronic states. Importantly,
+the role of fluorine is to control the structure, while maintaining high band
+gaps but does not directly provide large contributions to birefringence and the
+second harmonic generation as the conventional assumptions. This is a
+consequence of the microscopic electron distribution and the energy position of
+the fluorine states well below the valence band maxima. Based on our
+understandings, we constructed two artificial structure and they all behave as
+anticipated.",2312.01890v3
+2023-12-05,Accurate Machine Learning Predictions of Coercivity in High-Performance Permanent Magnets,"Increased demand for high-performance permanent magnets in the electric
+vehicle and wind turbine industries has prompted the search for cost-effective
+alternatives. Nevertheless, the discovery of new magnetic materials with the
+desired intrinsic and extrinsic permanent magnet properties presents a
+significant challenge. Traditional density functional theory (DFT) accurately
+predicts intrinsic permanent magnet properties such as magnetic moments,
+magneto-crystalline anisotropy constants, and exchange interactions. However,
+it cannot compute extrinsic macroscopic properties, such as coercivity ($H_c$),
+which are influenced by factors like microscopic defects and internal grain
+structures. Although micromagnetic simulation helps compute $H_c$, it
+overestimates the values almost by an order of magnitude due to Brown's
+paradox. To circumvent these limitations, we employ machine learning (ML)
+methods in an extensive database obtained from experiments, DFT calculations,
+and micromagnetic modeling. Our novel ML approach is computationally much
+faster than the micromagnetic simulation program, the mumax$^3$. We
+successfully utilize it to predict $H_c$ values for materials like cerium-doped
+$\mathrm{Nd}_2\mathrm{Fe}_{14}\mathrm{B}$, and subsequently compare the
+predicted values with experimental results. Remarkably, our ML model accurately
+identifies uniaxial magnetic anisotropy as the primary contributor to $H_c$.
+With DFT calculations, we predict the Nd-site dependent magnetic anisotropy
+behavior in $\mathrm{Nd}_2\mathrm{Fe}_{14}\mathrm{B}$, confirming $4f$-site
+planar and $4g$-site uniaxial to crystalline $c$-direction in good agreement
+with experiment. The Green's function atomic sphere approximation calculated a
+Curie temperature ($T_{\rm C}$) for $\mathrm{Nd}_2\mathrm{Fe}_{14}\mathrm{B}$
+that also agrees well with experiment.",2312.02475v3
+2023-12-05,Observable imprints of primordial gravitational waves on the temperature anisotropies of the Cosmic Microwave Background,"We examine the contribution of tensor modes, in addition to the dominant
+scalar ones, on the temperature anisotropies of the cosmic microwave background
+(CMB). To this end, we analyze in detail the temperature two-point angular
+correlation function $C(\theta)$ from the Planck 2018 dataset, focusing on
+large angles ($\theta \gtrsim 120^{\circ}$) corresponding to small $\ell$
+multipoles. A hierarchical set of infrared cutoffs are naturally introduced to
+the scalar and tensor power spectra of the CMB by invoking an extra
+Kaluza-Klein dimension compactifying at about the GUT scale between the Planck
+epoch and the start of inflation. We associate this set of lower scalar and
+tensor cutoffs with the parity of the multipole expansion of the $C(\theta)$
+function. By fitting the Planck 2018 data we compute the multipole coefficients
+thereby reproducing the well-known odd-parity preference in angular
+correlations seen by all three satellite missions COBE, WMAP and Planck. Our
+fits improve significantly once tensor modes are included in the analysis,
+hence providing a hint of the imprints of primordial gravitational waves on the
+temperature correlations observed in the CMB today. To conclude we suggest a
+relationship between, on the one hand, the lack of (positive) large-angle
+correlations and the odd-parity dominance in the CMB and, on the other hand,
+the effect of primordial gravitational waves on the CMB temperature
+anisotropies.",2312.02740v1
+2023-12-07,Effects of planetary day-night temperature gradients on He 1083 nm transit spectra,"A notable fraction of helium observations probing the evaporating atmospheres
+of short-period gas giants at 1083~nm exhibit a blueshift during transit, which
+might be indicative of a day-to-night side flow. In this study, we explore the
+gas dynamic effects of day-to-night temperature contrasts on the escaping
+atmosphere of a tidally locked planet. Using a combination of 3D hydrodynamic
+simulations and radiative transfer post-processing, we modeled the transmission
+spectra of the metastable helium triplet. Our key findings are as follows: (1)
+Increasing the day-night anisotropy leads to a narrowing of the helium line and
+an increase in the blueshift of the line centroid of a few km~s$^{-1}$. (2) The
+velocity shift of the line depends on the line-forming altitude, with higher
+planetary mass-loss rates causing the line to form at higher altitudes,
+resulting in a more pronounced velocity shift. (3) A critical point of
+day-night anisotropy comes about when the blueshift saturates, due to turbulent
+flows generated by outflow material falling back onto the planet's night side.
+(4) A strong stellar wind and the presence of turbulent flows may induce time
+variations in the velocity shift. Assuming that the day-night temperature
+gradient is the main cause of the observed blueshifts in the He-1083~nm
+triplet, the correlation between the velocity shift and day-night anisotropy
+provides an opportunity to constrain the temperature gradient of the
+line-forming region.",2312.04682v2
+2023-12-25,Exploration of the two-dimensional Ising magnetic materials in the triangular prismatic crystal field,"Magnetic anisotropy is essential for stabilizing two-dimensional (2D)
+magnetism, which has significant applications in spintronics and the
+advancement of fundamental physics. In this work, we examine the electronic
+structure and magnetic properties of triangular prismatic MSi$_2$N$_4$ (M = V,
+Cr) monolayers, using crystal field theory, spin-orbital state analyses, and
+density functional calculations. Our results reveal that the pristine
+VSi$_2$N$_4$ monolayer exhibits magnetism with a V$^{4+}$ 3$d^1$ $S$ = 1/2
+charge-spin state within the triangular prismatic crystal field. However, the
+strong $d$ orbital hybridization between adjacent V$^{4+}$ ions disrupts the
+$d$ orbital splitting in this crystal field, resulting in a relatively small
+in-plane magnetic anisotropy of approximately 2 $\mu$eV per V atom.In contrast,
+the pristine CrSi$_2$N$_4$ monolayer is nonmagnetic, characterized by the
+Cr$^{4+}$ 3$d^2$ $S$ = 0 state. Upon substituting nonmagnetic Cr$^{4+}$ with
+Si$^{4+}$, Cr$_\frac{1}{3}$Si$_\frac{8}{3}$N$_4$ transforms into an
+antiferromagnetic insulator with Cr$^{4+}$ 3$d^2$ $S$ = 1 state, featuring a
+large orbital moment of -1.06 $\mu_{\rm B}$ oriented along the $z$-axis and
+huge perpendicular magnetic anisotropy of 18.63 meV per Cr atom. These findings
+highlight the potential for further exploration of 2D Ising magnetic materials
+within a unique triangular prismatic crystal field.",2312.15625v1
+2023-12-29,Anisotropy-driven topological quantum phase transition in magnetic impurities,"A few years ago, a topological quantum phase transition (TQPT) has been found
+in Anderson and Kondo 2-channel spin-1 impurity models that include a hard-axis
+anisotropy term $DS_z^2$ with $D > 0$. The most remarkable manifestation of the
+TQPT is a jump in the spectral density of localized electrons, at the Fermi
+level, from very high to very low values as $D$ is increased. If the two
+conduction channels are equivalent, the transition takes place at the critical
+anisotropy $D_c \sim 2.5\; T_K$, where $T_K$ is the Kondo temperature for
+$D=0$. This jump might be important to develop a molecular transistor. The jump
+is due to a corresponding one in the Luttinger integral, which has a
+topological non-trivial value $\pi/2$ for $D > D_c$. Here, we review the main
+results for the spectral density and highlight the significance of the theory
+for the interpretation of measurements conducted on magnetic atoms or molecules
+on metallic surfaces. In these experiments, where $D$ is held constant, the
+energy scale $T_K$ is manipulated by some parameters. The resulting variation
+gives rise to a differential conductance $dI/dV$, measured by
+scanning-tunneling spectroscopy, which is consistent with a TQPT at an
+intermediate value of $T_K$. We also show that the theory can be extended to
+integer spin $S>1$ and two-impurity systems. This is also probably true for
+half-integer spin and non-equivalent channels in some cases.",2312.17702v1
+2023-12-31,CMB lensing from early-formed dark matter halos,"Some theoretical models for the early universe predict a spike-type
+enhancement in the primordial power spectrum on a small scale, which would
+result in forming early-formed dark matter halos (EFHs). In this work, we study
+the CMB lensing effect, considering the existence of EFHs, and investigate the
+potential to probe the EFHs and the primordial perturbations on scales smaller
+than $1\mathrm{Mpc}$. We numerically calculate the angular power spectrum of
+the lensing potential and the lensed CMB anisotropy of temperature, E-mode, and
+B-mode polarization, including the nonlinear effects of EFHs. We find the
+possibility that the lensed CMB temperature anisotropy is significantly
+enhanced on small scales, $\ell>1000$, and could be tested by component
+decomposition of observed signals through multi-frequency observations. Through
+the calculation with different models of the spiky-type power spectrum, we
+demonstrate that the accurate measurements of the CMB lensing effect would
+provide insight into the abundance of EFHs within the limited mass range around
+$10^{12}M_\odot$ and the primordial power spectrum on the limited scales around
+$k\sim 1\mathrm{Mpc}^{-1}$. In particular, we find that the existence of such
+EFHs can amplify the lensed anisotropy of CMB B-mode polarization even on large
+scales, $\ell <100$, as the overall enhancement by $\sim 10 \%$ level compared
+to the standard structure formation model without EFHs. Therefore, future CMB
+measurements such as the LiteBIRD satellite can probe the existence of the EFHs
+and the spike-type primordial power spectrum through the precise measurement of
+the large-scale CMB B-mode polarization.",2401.00407v1
+2023-12-31,Giant Optical Anisotropy in 2D Metal-Organic Chalcogenates,"Optical anisotropy is a fundamental attribute of some crystalline materials
+and is quantified via birefringence. A birefringent crystal not only gives rise
+to asymmetrical light propagation but also attenuation along two distinct
+polarizations, a phenomenon called linear dichroism (LD). Two-dimensional (2D)
+layered materials with high in- and out-of-plane anisotropy have garnered
+interest in this regard. Mithrene, a 2D metal-organic chalcogenate (MOCHA)
+compound, exhibits strong excitonic resonances due to its naturally occurring
+multi-quantum well (MQW) structure and in-plane anisotropic response in the
+blue wavelength (~400-500 nm) regime. The MQW structure and the large
+refractive indices of mithrene allow the hybridization of the excitons with
+photons to form self-hybridized exciton-polaritons in mithrene crystals with
+appropriate thicknesses. Here, we report the giant birefringence (~1.01) and
+tunable in-plane anisotropic response of mithrene, which stem from its low
+symmetry crystal structure and unique excitonic properties. We show that the LD
+in mithrene can be tuned by leveraging the anisotropic exciton-polariton
+formation via the cavity coupling effect exhibiting giant in-plane LD (~77.1%)
+at room temperature. Our results indicate that mithrene is an ideal polaritonic
+birefringent material for polarization-sensitive nanophotonic applications in
+the short wavelength regime.",2401.00590v2
+2024-01-22,Atomistic calculation of the f0 attempt frequency in Fe3O4 magnetite nanoparticles,"The Arrhenius law predicts the transition time between equilibrium states in
+physical systems due to thermal activation, with broad applications in material
+science, magnetic hyperthermia and paleomagnetism where it is used to estimate
+the transition time and thermal stability of assemblies of magnetic
+nanoparticles. Magnetite is a material of great importance in paleomagnetic
+studies and magnetic hyperthermia but existing estimates of the attempt
+frequency $f_0$ vary by several orders of magnitude in the range $10^7-10^{13}$
+Hz, leading to significant uncertainty in their relaxation rate. Here we
+present a dynamical method enabling full parameterization of the
+Arrhenius-N\'eel law using atomistic spin dynamics. We determine the
+temperature and volume dependence of the attempt frequency of magnetite
+nanoparticles with cubic anisotropy and find a value of $f_0 = 0.562 \pm 0.059$
+GHz at room temperature. For particles with enhanced anisotropy we find a
+significant increase in the attempt frequency and a strong temperature
+dependence suggesting an important role of anisotropy. The method is applicable
+to a wide range of dynamical systems where different states can be clearly
+identified and enables robust estimates of domain state stabilities, with
+particular importance in the rapidly developing field of micromagnetic analysis
+of paleomagnetic recordings where samples can be numerically reconstructed to
+provide a better understanding of geomagnetic recording fidelity over
+geological time scales.",2401.12080v1
+2024-01-23,Splitting Instability in Superalloys: A Phase-Field Study,"Precipitation-strengthened alloys, such as Ni-base, Co-base and Fe-base
+superalloys, show the development of dendrite-like precipitates in the solid
+state during aging at near-$\gamma^{\prime}$ solvus temperatures. These
+features arise out of a diffusive instability wherein, due to the point effect
+of diffusion, morphological perturbations over a growing sphere/cylinder are
+unstable. These dendrite-like perturbations exhibit anisotropic growth
+resulting from anisotropy in interfacial/elastic energies. Further,
+microstructures in these alloys also exhibit ""split"" morphologies wherein
+dendritic precipitates fragment beyond a critical size, giving rise to a
+regular octet or quartet pattern of near-equal-sized precipitates separated by
+thin matrix channels. The mechanism of formation of such morphologies has
+remained a subject of intense investigation, and multiple theories have been
+proposed to explain their occurrence. Here, we developed a phase-field model
+incorporating anisotropy in elastic and interfacial energies to investigate the
+evolution of these split microstructures during growth and coarsening of
+dendritic $\gamma^{\prime}$ precipitates. Our principal finding is that the
+reduction in elastic energy density drives the development of split morphology,
+albeit a concomitant increase in the surface energy density. We also find that
+factors such as supersaturation, elastic misfit, degree of elastic anisotropy
+and interfacial energy strongly modulate the formation of these
+microstructures. We analyze our simulation results in the light of classical
+theories of elastic stress effects on coarsening and prove that negative
+elastic interaction energy leads to the stability of split precipitates.",2401.13151v1
+2024-01-26,Observing Kinematic Anisotropies of the Stochastic Background with LISA,"We propose a diagnostic tool for future analyses of stochastic gravitational
+wave background signals of extra-galactic origin in LISA data. Next-generation
+gravitational wave detectors hold the capability to track unresolved
+gravitational waves bundled into a stochastic background. This composite
+background contains cosmological and astrophysical contributions, the
+exploration of which offers promising avenues for groundbreaking new insights
+into very early universe cosmology as well as late-time structure formation. In
+this article, we develop a full end-to-end pipeline for the extraction of
+extra-galactic signals, based on kinematic anisotropies arising from the
+galactic motion, via full-time-domain simulations of LISA's response to the
+gravitational wave anisotropic sky. Employing a Markov-Chain-Monte-Carlo
+map-making scheme, multipoles up to $\ell=2$ are recovered for scale-free
+spectra that support an interpretation as signals originating from cosmic
+strings in the case of a high signal-to-noise ratio. We demonstrate that our
+analysis is consistently beating cosmic variance and is robust against
+statistical and systematic errors. The impact of instrumental noise on the
+extraction of kinematic anisotropies is investigated, and we establish a
+detection threshold of $\Omega_{GW}\gtrsim 5\times 10^{-8}$ in the presence of
+instrument-induced noise. Potential avenues for improvement in our methodology
+are highlighted.",2401.14849v1
+2024-01-29,Accurate detection of diffusion anisotropy from an individual short particle trajectory,"In parallel with advances in microscale imaging techniques, the fields of
+biology and materials science have focused on precisely extracting particle
+properties based on their diffusion behavior. Although the majority of
+real-world particles exhibit anisotropy, their behavior has been studied less
+than that of isotropic particles. In this study, we introduce a new method for
+estimating the diffusion coefficients of individual anisotropic particles using
+short-trajectory data on the basis of a maximum likelihood framework.
+Traditional estimation techniques often use mean-squared displacement (MSD)
+values or other statistical measures that inherently remove angular
+information. Instead, we treated the angle as a latent variable and used belief
+propagation to estimate it while maximizing the likelihood using the
+expectation-maximization algorithm. Compared to conventional methods, this
+approach facilitates better estimation of shorter trajectories and faster
+rotations, as confirmed by numerical simulations and experimental data
+involving bacteria and quantum rods. Additionally, we performed an analytical
+investigation of the limits of detectability of anisotropy and provided
+guidelines for the experimental design. In addition to serving as a powerful
+tool for analyzing complex systems, the proposed method will pave the way for
+applying maximum likelihood methods to more complex diffusion phenomena.",2401.15909v1
+2024-02-05,Measuring jet energy loss fluctuations in the quark-gluon plasma via multiparticle correlations,"The quark-gluon plasma (QGP) is a high temperature state of matter produced
+in the collisions of two nuclei at relativistic energies. The properties of
+this matter at short distance scales are probed using jets with high transverse
+momentum ($p_T$) resulting from quarks and gluons scattered with large momentum
+transfer in the earliest stages of the collisions. The Fourier harmonics for
+anisotropies in the high transverse momentum particle yield, $v_n(p_T)$,
+indicate the path length dependence of jet energy loss within the QGP. We
+present a framework to build off of measurements of jet energy loss using
+$v_n(p_T)$ by characterizing fluctuations in jet energy loss that are currently
+not constrained experimentally. In this paper, we utilize a set of multivariate
+moments and cumulants as new experimental observables to measure event-by-event
+fluctuations in the azimuthal anisotropies of rare probes, and compare them to
+the azimuthal anisotropies of soft particles. Ultimately, these fluctuations
+can be used to quantify the magnitude and fluctuations of event-by-event jet
+energy loss. We relate these quantities to existing multivariate cumulant
+observables, highlight their unique properties, and validate their
+sensitivities with a Monte Carlo simulation.",2402.03512v1
+2024-02-15,Understanding and tuning magnetism in layered Ising-type antiferromagnet FePSe3 for potential 2D magnet,"Recent development in two-dimensional (2D) magnetic materials have motivated
+the search for new van der Waals magnetic materials, especially Ising-type
+magnets with strong magnetic anisotropy. Fe-based MPX3 (M = transition metal, X
+= chalcogen) compounds such as FePS3 and FePSe3 both exhibit an Ising-type
+magnetic order, but FePSe3 receives much less attention compared to FePS3. This
+work focuses on establishing the strategy to engineer magnetic anisotropy and
+exchange interactions in this less-explored compound. Through chalcogen and
+metal substitutions, the magnetic anisotropy is found to be immune against S
+substitution for Se whereas tunable only with heavy Mn substitution for Fe. In
+particular, Mn substitution leads to a continuous rotation of magnetic moments
+from the out-of-plane direction towards in-plane. Furthermore, the magnetic
+ordering temperature displays non-monotonic doping dependence for both
+chalcogen and metal substitutions but due to different mechanisms. These
+findings provide deeper insight into the Ising-type magnetism in this important
+van der Waals material, shedding light on the study of other Ising-type
+magnetic systems as well as discovering novel 2D magnets for potential
+applications in spintronics.",2402.10155v1
+2024-02-17,Anisotropic induced polarization modeling with neural networks and effective medium theory,"Accurately interpreting induced polarization (IP) data that reflects the
+inherent anisotropy of the Earth's crust requires anisotropic IP models. The
+Generalized Effective Medium Theory of Induced Polarization (GEMTIP) model
+effectively simulates the IP signatures of rocks containing polarizable
+minerals. A pivotal element of the GEMTIP model is calculating the
+depolarization tensor elements, an intensive task for anisotropic rocks because
+one must numerically solve six parametric integrals for each mineral inclusion.
+This study aims to streamline anisotropic IP simulations by extending the
+GEMTIP framework and introducing a machine learning approach to estimate the
+depolarization tensors. The theoretical contributions of this research are
+two-fold: (1) we augment the GEMTIP model to encompass anisotropic background
+conductivity and triaxial ellipsoidal inclusions, and (2) we reformulate the
+depolarization integrals to normalize their input and output variables,
+facilitating their estimation by neural networks. Validation against analytical
+solutions for spherical and spheroidal inclusions corroborates the accuracy of
+the neural network. Analyzing the neural network model, we find that the
+relationship between chargeability and polarizable inclusion content is
+increasingly uncertain for increasingly anisotropic rocks. A similar
+observation applies to the relationship between critical frequency and host
+rock conductivity. Moreover, the depolarization tensors are, on average, 56 %
+sensitive to inclusion anisotropy and 44 % sensitive to host rock conductivity
+anisotropy. Remarkably, our neural network drastically accelerates GEMTIP
+simulations--up to 100,000 times faster than numerical integration--without
+substantially sacrificing accuracy. This advancement is promising for efficient
+rock-scale IP modeling in complex and anisotropic geological settings.",2402.11313v1
+2024-02-21,Isotropic and anisotropic neutron star structure in 4D Einstein Gauss Bonnet Gravity,"With regard to the coupling constant and the strong magnetic field of neutron
+stars, we have studied these stars in the 4D Einstein Gauss Bonnet (4D EGB)
+gravity model in order to grasp a better understanding of these objects. In
+this paper, we have shown that the neutron star properties are considerably
+affected by the coupling constant and magnetic field. We have found that as a
+consequence of the strong magnetic field and the coupling constant, the maximum
+mass and radius of a neutron star are increasing functions of the coupling
+constant, while Schwarzschild radius, compactness, surface gravitational
+redshift, and Kretschmann scalar are decreasing functions. Additionally, our
+study has shown that the physical properties of a magnetized neutron star are
+greatly influenced not only by the strong magnetic field, but also by the
+anisotropy. Moreover, we have shown that to obtain the hydrostatic equilibrium
+configuration of the magnetized material, both the local anisotropy effect and
+the anisotropy due to the magnetic field should be considered. Finally, we have
+found that in the anisotropic magnetized neutron stars, the maximum mass and
+radius do not always increase with increasing the internal magnetic field.",2402.14038v1
+2024-02-22,On the origin of the above-room-temperature magnetism in the 2D van der Waals ferromagnet Fe$_3$GaTe$_2$,"Recent advancements in 2D magnetic materials have attracted a growing
+interest driven by their unique properties and potential applications in
+spintronic devices. However, the scarcity of systems that exhibit magnetism at
+room-temperature has limited their practical implementation into functional
+devices. In this work we focus on the recently synthetised van der Waals (vdW)
+ferromagnet Fe$_3$GaTe$_2$, which exhibits above-room-temperature magnetism
+(T$_{\mathrm{c}}$ = 350-380 K) and strong perpendicular magnetic anisotropy.
+Through first-principles calculations, we examine the magnetic properties of
+Fe$_3$GaTe$_2$ and compare them with the widely known Fe$_3$GeTe$_2$
+ferromagnet. Our calculations unveil the complex microscopic mechanisms
+governing their magnetic behaviour, emphasizing the pivotal role of the
+ferromagnetic in-plane exchange interactions in the stabilization of the
+elevated T$_{\mathrm{c}}$ in Fe$_3$GaTe$_2$. Additionally, we predict the
+stability, strong perpendicular anisotropy and high T$_{\mathrm{c}}$ of
+single-layer Fe$_3$GaTe$_2$. We also demonstrate the potential of strain
+engineering and electrostatic doping to modulate its magnetic exchange
+interactions and anisotropy. Our results incentivise the isolation of the
+monolayer and pave the way for the future optimization of Fe$_3$GaTe$_2$ in
+magnetic and spintronic nanodevices.",2402.14618v1
+2024-02-24,Collective excitations in two-dimensional harmonically trapped quantum droplets,"The collective excitation modes in quantum droplets trapped in a
+two-dimensional harmonic potential in the context of symmetric weakly
+interacting binary bosonic mixtures are studied. By utilizing the linearization
+technique, the time-dependent extended Gross-Pitaevskii equation, and a
+sum-rule approach with a variational approximation, the ground state properties
+and collective excitations of such a two-dimensional quantum system are
+investigated for various system parameters. We present comprehensive analysis
+and calculations on the effect of the confinement strength and anisotropy of
+the trapping potential, the number of atoms in the droplet, and the collective
+excitation modes. The radius of the droplet, as well as the chemical potential,
+is non-monotonically related to the number of atoms in the droplet, and the
+confinement tends to shift the minimum values towards the ideal gas limit. The
+excitation frequency peaks, which are prominent in a self-bounded droplet,
+become less pronounced and smoother when subjected to a strong trapping
+potential. The sum-rule approach fails to reproduce the breathing mode
+frequency for a moderate number of atoms in a weak trapping potential, however,
+works perfectly well in a strong confinement. It was found that the anisotropy
+in the trap eliminates the degeneracy between the quadrupole and scissors modes
+that occurs in an isotropic trap, causing the frequencies of these two modes to
+immediately diverge from each other for any degree of anisotropy. These
+findings provide valuable insights into the unique characteristics and behavior
+of quantum droplets, offering potential implications for future research and
+applications in the dynamic behaviors of intriguing quantum droplets.",2402.15811v1
+2024-02-29,Pressure-induced optical anisotropy of HfS$_2$,"The effect of pressure on Raman scattering (RS) in the bulk HfS$_2$ is
+investigated under hydrostatic and non-hydrostatic conditions. The RS lineshape
+does not change significantly in the hydrostatic regime, showing a systematic
+blueshift of the spectral features. In a non-hydrostatic environment, seven
+peaks emerge in the spectrum ($P$=7 GPa) dominating the lineshape up to
+$P$=10.5 GPa. The change in the RS lineshape manifests a pressure-induced phase
+transition in HfS$_2$. The simultaneous observation of both low-pressure (LP)
+and high-pressure (HP) related RS peaks suggests the corresponding coexistence
+of two different phases over a large pressure range. We found that the
+HP-related phase is metastable, persisting during the decompression cycle down
+to $P$=1.2 GPa with the LP-related features finally recovering at even lower
+pressures. The angle-resolved polarized RS (ARPRS) performed under $P$=7.4 GPa
+revealed a strong in-plane anisotropy of both the LP-related A$_{1g}$ mode and
+the HP peaks. The anisotropy is related to the possible distortion of the
+structure induced by the non-hydrostatic component of the pressure. We describe
+the obtained results by the influence of the non-hydrostatic pressure on the
+observed phase transition. We interpret our results in terms of a distorted
+$Pnma$ phase as a possible HP induced structure of HfS$_2$.",2402.19040v1
+2024-03-01,Equilibrium Model with Anisotropy for Model-Based Reconstruction in Magnetic Particle Imaging,"Magnetic particle imaging is a tracer-based tomographic imaging technique
+that allows the concentration of magnetic nanoparticles to be determined with
+high spatio-temporal resolution. To reconstruct an image of the tracer
+concentration, the magnetization dynamics of the particles must be accurately
+modeled. A popular ensemble model is based on solving the Fokker-Plank
+equation, taking into account either Brownian or N\'eel dynamics. The
+disadvantage of this model is that it is computationally expensive due to an
+underlying stiff differential equation. A simplified model is the equilibrium
+model, which can be evaluated directly but in most relevant cases it suffers
+from a non-negligible modeling error. In the present work, we investigate an
+extended version of the equilibrium model that can account for particle
+anisotropy. We show that this model can be expressed as a series of Bessel
+functions, which can be truncated based on a predefined accuracy, leading to
+very short computation times, which are about three orders of magnitude lower
+than equivalent Fokker-Planck computation times. We investigate the accuracy of
+the model for 2D Lissajous MPI sequences and show that the difference between
+the Fokker-Planck and the equilibrium model with anisotropy is sufficiently
+small so that the latter model can be used for image reconstruction on
+experimental data with only marginal loss of image quality, even compared to a
+system matrix-based reconstruction.",2403.00602v1
+2024-03-06,The role of interfacial interactions and oxygen vacancies in tuning magnetic anisotropy in LaCrO$_{3}$/LaMnO$_{3}$ heterostructures,"The interplay of lattice, electronic, and spin degrees of freedom at
+epitaxial complex oxide interfaces provides a route to tune their magnetic
+ground states. Unraveling the competing contributions is critical for tuning
+their functional properties. We investigate the relationship between magnetic
+ordering and magnetic anisotropy and the lattice symmetry, oxygen content, and
+film thickness in compressively strained LaMnO$_3$/LaCrO$_3$ superlattices.
+Mn-O-Cr antiferromagnetic superexchange interactions across the heterointerface
+resulting in a net ferrimagnetic magnetic structure. Bulk magnetometry
+measurements reveal isotropic in-plane magnetism for as-grown oxygen-deficient
+thinner thin samples due to equal fractions of orthorhombic a+a-c-, and a-a+c-
+twin domains. As the superlattice thickness is increased, in-plane magnetic
+anisotropy emerges as the fraction of the a+a-c- domain increases. On annealing
+in oxygen, the suppression of oxygen vacancies results in a contraction of the
+lattice volume, and an orthorhombic to rhombohedral transition leads to
+isotropic magnetism independent of the film thickness. The complex interactions
+are investigated using high-resolution synchrotron diffraction and X-ray
+absorption spectroscopy. These results highlight the role of the evolution of
+structural domains with film thickness, interfacial spin interactions, and
+oxygen-vacancy-induced structural phase transitions in tuning the magnetic
+properties of complex oxide heterostructures.",2403.03764v1
+2024-03-18,Measurement of anisotropies in Supernova Remnant observations and their interpretation using numerical models,"Supernova remnants (SNRs) exhibit varying degrees of anisotropy, which have
+been extensively modeled using numerical methods. We implement a technique to
+measure anisotropies in SNRs by calculating power spectra from their
+high-resolution images. To test this technique, we develop 3D hydrodynamical
+models of supernova remnants and generate synthetic x-ray images from them.
+Power spectra extracted from both the 3D models and the synthetic images
+exhibit the same dominant angular scale, which separates large scale features
+from small scale features due to hydrodynamic instabilities. The angular power
+spectrum at small length scales during relatively early times is too steep to
+be consistent with Kolmogorov turbulence, but it transitions to Kolmogorov
+turbulence at late times. As an example of how this technique can be applied to
+observations, we extract a power spectrum from a \textit{Chandra} observation
+of Tycho's SNR and compare with our models. Our predicted power spectrum picks
+out the angular scale of Tycho's fleece-like structures and also agrees with
+the small-scale power seen in Tycho. We use this to extract an estimate for the
+density of the circumstellar gas ($n \sim 0.28/\mathrm{cm^3}$), consistent with
+previous measurements of this density by other means. The power spectrum also
+provides an estimate of the density profile of the outermost ejecta. Moreover,
+we observe additional power at large scales which may provide important clues
+about the explosion mechanism itself.",2403.12264v1
+2024-03-24,"Aggregate Frequency Width, Nuclear Hyperfine Coupling and Jahn-Teller Effect of $Cu^{2+}$ Impurity Ion ESR in $SrLaAlO_4$ Dielectric Resonator at $20$ Millikelvin","The impurity paramagnetic ion, $Cu^{2+}$ substitutes $Al$ in the $SrLaAlO_4$
+single crystal lattice, this results in a $CuO_6$ elongated octahedron, the
+resulting measured g-factors shows four-fold axes variation condition. The
+aggregate frequency width of the electron spin resonance with the required
+minimum level of impurity concentration has been evaluated in single crystal
+$SrLaAlO_4$ at $20$ millikelvin. Measured parallel hyperfine constants,
+$A_{\scriptscriptstyle\parallel Cu}$, were determined to be
+$-155.7\times10^{-4}~cm^{-1},~ -163.0\times10^{-4}~cm^{-1},~
+-178.3\times10^{-4}~cm^{-1} $ and$~-211.1\times10^{-4}~cm^{-1}$ at
+$9.072~GHz~(WGH_{4,1,1})$ for the nuclear magnetic quantum number
+$M_I=+\frac{3}{2},+\frac{1}{2},-\frac{1}{2}$,~and$-\frac{3}{2}$ respectively.
+The anisotropy of the hyperfine structure reveals a characteristics of static
+Jahn-Teller effect. The second-order-anisotropy-term, $\sim
+(\frac{spin-orbit~coupling}{10D_q})^2$, is significant and can not be
+disregarded, with the local strain dominating over the observed
+Zeeman-anisotropy-energy difference. The Bohr electron magneton,
+$\beta=9.23\times 10^{-24} JT^{-1}$, (within $-0.43\%$ so-called experimental
+error) has been found using the measured spin-Hamiltonian parameters. Measured
+nuclear dipolar hyperfine structure parameter
+$P_{\scriptscriptstyle\parallel}=12.3\times10^{-4}~cm^{-1}$ shows that the mean
+inverse third power of the electron distance from the nucleus is $\langle
+r^{-3}_q\rangle\simeq 5.23$ a.u. for $Cu^{2+}$ ion in the substituted $Al^{3+}$
+ion site assuming nuclear electric quadruple moment $Q=-0.211$ barn.",2403.16315v1
+1993-05-07,Statistics of N-body Simulations I. Equal Masess Before Core Collapse,"We study the dynamical evolution of idealised stellar systems by averaging
+results from many $N$-body simulations, each having modest numbers of stars.
+For isolated systems with stars of uniform mass, we discuss aspects of
+evolution up to the point of core collapse: relaxation and its $N$-dependence,
+the evolution of the density profile, the development of the velocity
+dispersion and anisotropy, and the rate of stellar escape.",9305008v1
+1993-09-29,Blue perturbation spectra from inflation,"We investigate inflationary models leading to density perturbations with a
+spectral index $n>1$ (``blue spectra""). These perturbation spectra may be
+useful to simultaneously account for both the amount of ultra large-scale power
+required to fit cosmic microwave background anisotropies, such as those
+measured by COBE, and that required to give bulk motions and structures on the
+$\sim 50~h^{-1}$ Mpc scale.",9309054v1
+1994-08-01,Polarization-Temperature Correlations in the Microwave Background,"The polarization of the CMB offers a potentially valuable probe of the
+physics of the early universe, specifically of the velocity of the
+photon-baryon fluid on the last scattering surface. Here we discuss
+qualitatively the correlations that arise between the temperature anisotropies
+and polarization of the CMB and how they might be observed.",9408001v1
+1994-08-05,BIMA observations of possible microwave background sources,"We present sensitive upper limits on the 90 GHz flux of known radio and
+infrared sources in regions associated with possible cosmic microwave
+background fluctuations at 0.5--1 degree scales. Specifically we look at the
+MAX GUM region and the region of strongest fluctuation in the MSAM scan. None
+of the known sources can account for the levels of anisotropy seen.",9408021v1
+1994-10-27,A First Map of the CMB at 0.5Deg Resolution,"We use a Maximum Entropy technique to reconstruct a map of the microwave sky
+near the star Gamma Ursae Minoris, based on data from flights 2, 3 and 4 of the
+Millimeter-wave Anisotropy eXperiment (MAX).",9410088v1
+1995-07-10,The COBRAS/SAMBA CMB Project,"COBRAS/SAMBA is a second generation satelitte dedicated to mapping at high
+resolution and sensitivity the anisotropies of the Cosmic Microwave Background
+(CMB). This mission is in the assessment study phase (A) at ESA, with a
+decision expected mid 1996, for a launch around 2003.",9507032v1
+1995-08-01,The Open Universe Grishchuk-Zel'dovich Effect,"The Grishchuk--Zel'dovich effect is the contribution to the microwave
+background anisotropy from an extremely large scale adiabatic density
+perturbation, on the standard hypothesis that this perturbation is a typical
+realization of a homogeneous Gaussian random field. We analyze this effect in
+open universes, corresponding to density parameter $\Omega_0<1$ with no
+cosmological constant, and concentrate on the recently discussed
+super-curvature modes. The effect is present in all of the low multipoles of
+the anisotropy, in contrast with the $\Omega_0=1$ case where only the
+quadrupole receives a contribution. However, for no value of $\Omega_0$ can a
+very large scale perturbation generate a spectrum capable of matching
+observations across a wide range of multipoles. We evaluate the magnitude of
+the effect coming from a given wavenumber as a function of the magnitude of the
+density perturbation, conveniently specified by the mean-square curvature
+perturbation. From the absence of the effect at the observed level, we find
+that for $0.25\leq\Omega_0\leq 0.8$, a curvature perturbation of order unity is
+permitted only for inverse wavenumbers more than one thousand times the size of
+the observable universe. As $\Omega_0$ tends to one, the constraint weakens to
+the flat space result that the inverse wavenumber be more than a hundred times
+the size of the observable universe, whereas for $\Omega_0 < 0.25$ it becomes
+stronger. We explain the physical meaning of these results, by relating them to
+the correlation length of the perturbation. Finally, in an Appendix we consider
+the dipole anisotropy and show that it always leads to weaker constraints.",9508003v2
+1995-10-05,Metric Perturbations from Quantum Tunneling in Open Inflation,"We study the effect that quantum fluctuations produced during the nucleation
+of a single-bubble open inflationary universe have on the amplitude of
+temperature anisotropies in the microwave background. We compute the instanton
+action for the quantum tunneling between the false and true vacua in open
+inflation models and show that the amplitude of quantum fluctuations of the
+bubble wall is very sensitive to the gravitational effects of the true vacuum.
+We study the spectrum of quantum fluctuations of the bubble wall and confirm
+that there is only an inhomogeneous ($k^2 = -3$) discrete mode associated with
+transverse traceless fluctuations of the bubble wall. This super-curvature mode
+could in principle distort the anisotropy of the microwave background. We
+compute the amplitude of the gauge invariant metric perturbations induced by
+the bubble wall fluctuations on a comoving hypersurface, and calculate the
+induced amplitude of temperature fluctuations in the microwave background, for
+arbitrary values of $\Omega_0$. We find that in the limit $\Omega_0\simeq 1$,
+the quadrupole dominates the angular power spectrum, like in the usual
+Grishchuk-Zel'dovich effect. The resulting bounds on the amplitude of quantum
+fluctuations of the bubble wall from the absence of such an effect in the
+observed microwave background anisotropies are quite strong. We also study the
+contribution from a discrete long wavelength super-curvature mode ($k^2 \simeq
+2m^2/3H^2$) that appears in the spectrum of open de Sitter vacuum fluctuations.
+We constrain the parameters of the models of open inflation so that these modes
+do not distort the observed temperature anisotropy.",9510029v4
+1996-02-27,UCSB South Pole 1994 CMB anisotropy measurement constraints on open and flat-Lambda CDM cosmogonies,"We develop methods to account for experimental and observational
+uncertainties in likelihood analyses of data from cosmic microwave background
+(CMB) anisotropy experiments and apply them to an analysis of the UCSB South
+Pole 1994 (SP94) experiment. Observationally motivated open and spatially-flat
+$\Lambda$, cold dark matter cosmogonies are considered. Among the models we
+consider, the full SP94 data set is most consistent with $\Omega_0 \sim
+0.1-0.2$ open models and less so with old $(t_0 \gap 15 - 16 Gyr)$, high baryon
+density $(\Omega_B \gap 0.0175 h^{-2})$, low density ($\Omega_0 \sim 0.2 -
+0.4), flat-$\Lambda$ models. The SP94 data do not rule out any of the models we
+consider at the $2\sigma$ level. The SP94 experiment is most sensitive to
+anisotropies on a somewhat larger, model-dependent, angular scale than the
+scale at which the window function peaks. For establishing the significance of
+a detection of CMB anisotropy we derive limits using the highest posterior
+density (HPD) prescription, since it yields smaller lower limits. Since HPD
+limits lead to tighter constraints on the CMB amplitude, they also provide for
+greater discrimination between models. Model normalizations deduced from the
+SP94 data subsets are mostly consistent with those deduced from the two-year
+COBE-DMR data, although the Ka-band data prefer a normalization $\sim 1\sigma$
+lower than do the Q-band data, the Q and Ka + Q data favour a slightly higher
+normalization for the $\Omega_0 = 0.1$ open model than does the DMR, and the Ka
+and Ka + Q data prefer a somewhat lower normalization for the older, higher
+$\Omega_B$, low-density $\Lambda$ models than does the DMR.",9602141v2
+1996-06-09,Open universes from bubbles: an introduction and update,"An introduction to models of open universes originating from bubbles,
+including a summary of recent theoretical results for the power spectrum. To
+appear in the proceedings of the XXXIth Moriond meeting, ""Microwave Background
+Anisotropies.""",9606052v2
+1996-09-03,Ω_0 and λ_0 from galaxy and quasar clustering: cosmic virial theorem and cosmological redshift-space distortion,"I discuss two cosmological tests to determine the cosmological density
+parameter \Omega_0 the cosmological constant \lambda_0, which make use of the
+anisotropy of the two-point correlation functions due to the peculiar velocity
+field and the cosmological redshift-space distortion.",9609014v1
+1996-09-15,The MAX and MAXIMA Experiments,"We summarize the performance of the MAX experiment during its 5 years of
+operation and present a compilation of the results to date. We describe MAXIMA,
+a balloon borne experiment employing an array of detectors in the focal plane,
+that will provide sensitive measurements of the power spectrum between l~60 and
+l~650.",9609098v1
+1997-02-19,Non-Gaussian Spectra in the Cosmic Microwave Background,"We propose a set of new statistics which can be extracted out of the angular
+distribution of the Fourier transform of the temperature anisotropies in the
+small field limit. They quantify generic non-Gaussian structure and complement
+the power spectrum in characterizing the sampled distribution function of a
+data set (contribution to the 18th Texas Symposium Proceedings)",9702164v1
+1997-02-22,The Maxima and Boomerang Experiments,"MAXIMA and BOOMERanG are balloon borne experiments designed to map the cosmic
+microwave background anisotropy power spectrum from l=10 to l=900 with high
+resolution. Here we describe the program of observations, the experiments,
+their capabilities, and their expected performance.",9702200v1
+1997-03-31,Topological defects and open inflation,"Topological defects can naturally be formed soon after bubble nucleation in
+the open inflation scenario. The defects are not completely diluted away by the
+subsequent period of inflation in the bubble interior and can produce
+observable large-scale microwave background anisotropies. Superheavy strings
+and monopoles attached to the strings can act as gravitational lenses with
+angular separation between the images of up to an arc minute.",9703201v1
+1997-05-30,On the rotation of the universe,"We point on a different possible explanation of the observations reported
+recently by Nodland and Ralston, PRL 78 (1997) 3043 [astro-ph/9704196]. The
+dipole anisotropy of the polarization of radiation from the distant radio
+sources can be caused by the global cosmic rotation. This explanation is of
+purely geometric origin and is completely within the conventional physics.",9705243v1
+1997-10-13,Breaking the degeneracy between anisotropy and mass: The dark halo of the E0 galaxy NGC 6703,"(abridged) We have measured line-of-sight velocity profiles (VPs) in the E0
+galaxy NGC 6703 out to 2.6 R_e. From these data we constrain the mass
+distribution and the anisotropy of the stellar orbits in this galaxy.
+  We have developed a non-parametric technique to determine the DF f(E,L^2)
+directly from the kinematic data. From Monte Carlo tests using the spatial
+extent, sampling, and error bars of the NGC 6703 data we find that smooth
+underlying DFs can be recovered to an rms accuracy of 12%, and the anisotropy
+parameter beta(r) to an accuracy of 0.1, in a given potential. An
+asymptotically constant halo circular velocity v_0 can be determined with an
+accuracy of +- \lta 50km/s.
+  For NGC 6703 we determine the true circular velocity at 2.6 R_e to be 250 +-
+40km/s at 95% c.l., corresponding to a total mass in NGC 6703 inside 78'' (13.5
+h_50^-1 kpc), of 1.6-2.6 x 10^11 h_50^-1 Msun. No model without dark matter
+will fit the data; however, a maximum stellar mass model in which the luminous
+component provides nearly all the mass in the centre does. In such a model, the
+total luminous mass inside 78'' is 9 x 10^10 Msun and the integrated
+M/L_B=5.3-10, corresponding to a rise from the center by at least a factor of
+1.6.
+  The anisotropy of the stellar distribution function in NGC 6703 changes from
+near-isotropic at the centre to slightly radially anisotropic (beta=0.3-0.4 at
+30'', beta=0.2-0.4 at 60'') and is not well-constrained at the outer edge of
+the data.
+  Our results suggest that also elliptical galaxies begin to be dominated by
+dark matter at radii of \sim 10kpc.",9710129v1
+1997-11-08,The Cosmic Background Radiation,"We summarise the current status of cosmic microwave background spectrum and
+anisotropy measurements, and their theoretical interpretation. This is the
+update of the mini-review for the 1997 web-version of the Review of Particle
+Properties.",9711069v1
+1997-11-27,Textures and Cosmic Microwave Background non-Gaussian Signatures,"We report briefly on a recent analysis of the texture-induced CMB radiation
+three-point correlation function of temperature anisotropies as predicted by an
+analytical model. We specialize our analysis to both large-scales (e.g., for
+COBE-DMR, where we compare our prediction with the actual four-year data) and
+intermediate-scales. We show how the latter case puts strong constraints on the
+model parameters.",9711343v1
+1998-01-15,Inflation and the cosmic microwave background,"I give a status report and outlook concerning the use of the cosmic microwave
+background anisotropies to constrain the inflationary cosmology, and stress its
+crucial role as an underlying paradigm for the estimation of cosmological
+parameters.",9801148v1
+1998-03-06,Generation of Gravitational Waves and Scalar Perturbations in Inflation with Effective $Λ$-term and T/S Story,"We argue that gravitational wave contribution to the cosmic microwave
+background anisotropy at angular scale $\sim 10^0$ may exceed 50% for some
+models of hybrid inflation producing standard cosmology with the density
+perturbation slope $n \simeq 1$.",9803064v1
+1998-03-13,Inflation and the microwave background,"I discuss the interplay between inflation and microwave background
+anisotropies, stressing in particular the accuracy with which inflation
+predictions need to be made, and the importance of inflation as an underlying
+paradigm for cosmological parameter estimation.",9803152v1
+1998-03-18,Anisotropy of CMB & Cosmological Model,"In this brief review I will touch upon the main points and thends of
+observational and theoretical cosmology, that influence and change today our
+understanding of the Universe.",9803212v1
+1998-04-17,CMB anisotropies on circular scans,"We address the problem of map-making with data from the Planck Surveyor High
+Frequency Instrument, with an emphasis on the understanding and modelling of
+instrumental effects, and in particular that of sidelobe straylight. We propose
+a map-making method which takes advantage of the very special properties of the
+Planck scanning strategy along circular scans.",9804180v1
+1998-07-31,Reconstructing the Primordial Power Spectrum,"Cosmological models predict transfer functions by which primordial density
+perturbations develop into CMB anisotropy and Large-Scale Structure. We use the
+current set of observations to reconstruct the primordial power spectrum for
+standard CDM, CDM with a cosmological constant, open CDM, and standard CDM with
+a high baryon content.",9807328v1
+1998-11-11,Cosmic microwave background: polarization and temperature anisotropies from symmetric structures,"I consider the case of anisotropies in the Cosmic Microwave Background (CMB)
+from one single ordered perturbation source, or seed, existing well before
+decoupling between matter and radiation. Such structures could have been left
+by high energy symmetries breaking in the early universe.
+  I focus on the cases of spherical and cylindrical symmetry of the seed. I
+give general analytic expressions for the polarization and temperature linear
+perturbations, factoring out of the Fourier integral the dependence on the
+photon propagation direction and on the geometric coordinates describing the
+seed. I show how the CMB perturbations manifestly reflect the symmetries of
+their seeds. CMB anisotropies are obtained with a line of sight integration.
+  This treatment highlights the undulatory properties of the CMB. I show with
+numerical examples how the polarization and temperature perturbations propagate
+beyond the size of their seeds, reaching the CMB sound horizon at the time
+considered. Just like the waves from a pebble thrown in a pond, CMB anisotropy
+from a seed intersecting the last scattering surface appears as a series of
+temperature and polarization waves surrounding the seed, extending on the scale
+of the CMB sound horizon at decoupling, roughly $1^{o}$ in the sky. Each wave
+is characterized by its own value of the CMB perturbation, with the same mean
+amplitude of the signal coming from the seed interior.
+  These waves could allow to distinguish relics from high energy processes of
+the early universe from point-like astrophysical sources, because of their
+angular extension and amplitude. Also, the marked analogy between polarization
+and temperature signals offers cross correlation possibilities for the future
+Planck Surveyor observations.",9811176v3
+1998-11-24,Perturbations in Quintessential Inflation,"Recently Peebles and Vilenkin proposed and quantitatively analyzed the
+fascinating idea that a substantial fraction of the present cosmic energy
+density could reside in the vacuum potential energy of the scalar field
+responsible for inflation (quintessential inflation). Here we compute the
+signature of this model in the cosmic microwave background polarization and
+temperature anisotropies and in the large scale structure.",9811385v1
+1999-03-15,Anisotropies in the CMB,"The ten's of micro-Kelvin variations in the temperature of the cosmic
+microwave background (CMB) radiation across the sky encode a wealth of
+information about the Universe. The full-sky, high-resolution maps of the CMB
+that will be made in the next decade should determine cosmological parameters
+to unprecedented precision and sharply test inflation and other theories of the
+early Universe.",9903232v1
+1999-07-22,Constraints on the Cosmological Parameters using CMB observations,"This paper covers several techniques of intercomparison of Cosmic Microwave
+Background (CMB) anisotropy experiments and models of structure formation. It
+presents the constraints on several cosmological parameters using current CMB
+observations.",9907312v1
+1999-08-17,The 2-10 keV XRB dipole and its cosmological implications,"The hard X-ray (>2 keV) emission of the local and distant Universe as
+observed with the HEAO1-A2 experiment is reconsidered in the context of large
+scale cosmic structure. Using all-sky X-ray samples of AGN and galaxy clusters
+we remove the dominant local X-ray flux from within a redshift of ~ 0.02. We
+evaluate the dipolar and higher order harmonic structure in 4 X-ray colours.
+The estimated dipole anisotropy of the unresolved flux appears to be consistent
+with a combination of the Compton-Getting effect due to the Local Group motion
+(dipole amplitude Delta = 0.0042) and remaining large scale structure (0.0023
+<~ Delta <~ 0.0085), in good agreement with the expectations of Cold Dark
+Matter models. The observed anisotropy does however also suggest a
+non-negligible Galactic contribution which is more complex than current, simple
+models of >2 keV Galactic X-ray emission. Comparison of the soft and hard
+colour maps with a harmonic analysis of the 1.5 keV ROSAT all-sky data
+qualitatively suggests that at least a third of the faint, unresolved ~ 18 deg
+scale structure in the HEAO1-A2 data may be Galactic in origin. However, the
+effect on measured flux dipoles is small (<~3%).
+  We derive an expression for dipole anisotropy and acceleration and
+demonstrate how the dipole anisotropy of the distant X-ray frame can constrain
+the amplitude of bulk motions of the universe. From observed bulk motions over
+a local ~ 50 Mpc/h radius volume we determine 0.14 <~ Omega^0.6/b_x(0) <~ 0.59.",9908187v2
+1999-11-30,Effects of inflationary bubbles on the polarization and temperature anisotropies of the cosmic microwave background,"We predict the imprint of linear bubbly perturbations on the polarization and
+temperature anisotropies of the cosmic microwave background (CMB).
+  We analytically model a bubbly density perturbation at the beginning of the
+radiation dominated era and we apply the linear theory of cosmological
+perturbations to compute its time evolution. At decoupling, it uniquely signs
+the CMB polarization and temperature anisotropy sky. During evolution the
+perturbation propagates beyond the size of the bubble and reaches the CMB sound
+horizon at the time considered. Therefore, its signal appears as a series of
+concentric rings, each characterized by its own amplitude and sign, on the
+scale of 1^{o} on the sky, even if the real seed size is much smaller.
+Polarization and temperature rings are strictly correlated. As expected for
+linear perturbations with size L and density contrast \delta at decoupling,
+\delta T/T is roughly \delta (L/H^{-1})^{2}; the polarization is about 10% of
+the temperature anisotropy.
+  We predict the impact of a distribution of bubbles on the CMB polarization
+and temperature power spectra. Considering models containing both CDM Gaussian
+and bubbly non-Gaussian fluctuations, we simulate and analyze 10^{o} x 10^{o}
+sky patches with angular resolution of about 3.5^{'}. The CMB power associated
+with the bubbles is entirely on sub-degree angular scales (200<= l<=1000), that
+will be explored by the forthcoming high resolution CMB experiments with the
+percent precision. Depending on the parameters of the bubbly distribution we
+find extra-power with respect to the ordinary CDM Gaussian fluctuations; we
+infer simple analytical scalings of the power induced by bubbly perturbations
+and we constrain our parameters with the existing data.",9911530v1
+2000-01-25,Stellar Dynamics in the Galactic centre: Proper Motions and Anisotropy,"We report a new analysis of stellar dynamics in the Galactic centre, based on
+improved sky and LOS velocities for >100 stars within a few arcsec of SgrA*.
+Overall the motions do not deviate strongly from isotropy. For 32 stars with
+all 3 components determined the absolute, LOS and sky velocities agree well, as
+for a spherical cluster. The projected radial and tangential motions of all 104
+pm stars are also consistent with overall isotropy. However, the projected
+velocities of the young, early type stars have a strong radial dependence. Most
+of the bright HeI stars 1-10"" from SgrA* are on tangential orbits. This
+anisotropy of the HeI stars and most of the brighter IRS16 complex members is
+largely caused by a CW and counter-rotating, coherent rotation pattern. The
+overall rotation of the young star cluster probably is a remnant of the angular
+momentum in the cloud these stars formed from. The fainter, fast stars within
+\~1"" of SgrA* appear to be largely moving on radial or very elliptical orbits.
+We have not detected nonlinear motion for any of them. Most of the SgrA*
+cluster members also are on CW orbits. Spectroscopy shows them to be early type
+stars. We propose that the SgrA* cluster stars are those members of the early
+type cluster with small angular momentum which can plunge to the vicinity of
+SgrA*. Our anisotropy-independent estimate of the Sun-GC distance is 7.8-8.2
+kpc (+/- 0.9 kpc). We include velocity anisotropy in estimating the central
+mass distribution. We confirm previous conclusions that a compact central mass
+concentration is present and dominates the potential from 0.01-1 pc. The
+central mass ranges from 2.6-3.3E6 M_sun. (abridged)",0001428v1
+2000-03-22,The best unbiased estimator for the CMB angular bispectrum,"For those angular multipoles where cosmic variance is an issue,
+non-Gaussianities in the Cosmic Microwave Background (CMB) anisotropies will be
+hard to detect. Here, we construct explicitly the best unbiased estimator for
+the CMB angular bispectrum.",0003335v1
+2000-03-23,Cosmological Strucure Formation with Topological Defects,"Structure formation with topological defects is described. The main
+differences from inflationary models are highlighted. The results are compared
+with recent observations. It is concluded that all the defect models studied so
+far are in disagreement with recent observations of CMB anisotropies.
+Furthermore, present observations do not support 'decoherence', a generic
+feature of structure formation from topological defects.",0003363v1
+2000-06-28,Bayesian Methods for Cosmological Parameter Estimation from Cosmic Microwave Background Measurements,"We present a strategy for a statistically rigorous Bayesian approach to the
+problem of determining cosmological parameters from the results of observations
+of anisotropies in the cosmic microwave radiation background. We propose the
+application of Markov chain Monte Carlo methods, specifically the
+Metropolis-Hastings algorithm, to estimate the parameters. A complete
+statistical analysis is presented, with the Metropolis-Hastings algorithm
+described in detail.",0006401v1
+2000-12-01,$Λ$-Inflation and CMBR Anisotropy,"We argue that a $\Lambda$-inflation model can ensure large relative
+contribution of cosmic gravity waves into the $\Delta T/T$ at COBE scale
+preserving at the same time a near scale-invariant spectrum of cosmological
+density perturbations favored by observational data ($n_S\simeq 1$). High
+efficiency of these models to meet observational tests is discussed.",0012014v1
+2001-03-13,Quintessence and the first Doppler peak,"By using a tracking quintessence model we obtain that the position of the
+first Doppler peak in the spectrum of CMB anisotropies only depends on the
+topology of the universe, $\Omega_k$, for any value of the ratio
+$\Omega_{\Lambda}/\Omega_M$, so that such a dependence is perfectly valid in
+the range suggested by supernova observations.",0103194v1
+2001-08-03,"Toward a Measurement of the Cosmological Geometry at z~2: Predicting Lyman-alpha Forest Correlation in Three Dimensions, and the Potential of Future Data Sets","The correlation between Lyman-alpha absorption in the spectra of quasar pairs
+can be used to measure the transverse distance scale at z~2, which is sensitive
+to the cosmological constant (Omega_Lambda) or other forms of vacuum energy.
+Using Hydro-PM simulations, I compute the three-dimensional power spectrum of
+the Lyman-alpha forest flux, P_F(k,mu), from which the redshift-space
+anisotropy of the correlation can be obtained. I find that box size ~40 Mpc/h
+and resolution ~40 Kpc/h are necessary for convergence of the calculations to
+<5% on all relevant scales, although somewhat poorer resolution can be used for
+large scales. I compute directly the linear theory bias parameters of the
+Lyman-alpha forest, potentially allowing simulation results to be extended to
+arbitrarily large scales. I investigate the dependence of P_F(k,mu) on the
+primordial power spectrum, the temperature-density relation of the gas, and the
+mean flux decrement, finding that the redshift-space anisotropy is relatively
+insensitive to these parameters. A table of results is provided for different
+parameter variations. I investigate the constraint that can be obtained on
+Omega_Lambda using quasars from a large survey. Assuming 13 (theta/1')^2 pairs
+at separation <theta, and including separations <10', a measurement to <5% can
+be made if simulations can predict the redshift-space anisotropy with <5%
+accuracy, or to <10% if the anisotropy must be measured from the data. The
+Sloan Digital Sky Survey (SDSS) will obtain spectra for a factor ~5 fewer pairs
+than this, so followup observations of fainter pair candidates will be
+necessary. I discuss the requirements on spectral resolution and
+signal-to-noise ratio (SDSS-quality spectra are sufficient).",0108064v1
+2001-09-12,Separation of instrumental and astrophysical foregrounds for mapping CMB anisotropies,"We address the extended problem of component separation for CMB applications
+when a mixture of both astrophysical and instrumental components are present in
+the observations, and show how standard methods can be adapted to handle this
+more complex inversion problem.",0109187v1
+2001-11-27,CMB: The ultimate test for theoretical models aiming at describing the very early universe,"In this talk, I will illustrate how one can use the cosmic microwave
+background anisotropy measurements, in order to test theoretical models aiming
+at describing the early universe.",0111501v1
+2002-04-16,Cosmology Rounding the Cape,"A survey is made of the present observational status on cosmological
+parameters from microwave background anisotropies. I then move to some
+non-standard aspect of parameter extraction like quintessence, extra-background
+of relativistic particles and variations in fundamental constants.",0204262v1
+2002-05-10,Ultrahigh energy cosmic rays from dark matter annihilation,"Annihilation of clumped superheavy dark matter provides an interesting
+explanation for the origin of ultrahigh energy cosmic rays.
+  The predicted anisotropy signal provides a unique signature for this
+scenario.",0205158v1
+2002-09-26,"CMB Anisotropy Constraints on Flat-Lambda and Open CDM Cosmogonies from DMR, UCSB South Pole, Python, ARGO, MAX, White Dish, OVRO, and SuZIE Data","We use joint likelihood analyses of combinations of fifteen cosmic microwave
+background (CMB) anisotropy data sets from the DMR, UCSB South Pole 1994,
+Python I--III, ARGO, MAX 4 and 5, White Dish, OVRO, and SuZIE experiments to
+constrain cosmogonies. We consider open and spatially-flat-Lambda cold dark
+matter cosmogonies, with nonrelativistic-mass density parameter Omega_0 in the
+range 0.1--1, baryonic-mass density parameter Omega_B in the range
+(0.005--0.029) h^{-2}, and age of the universe t_0 in the range (10--20) Gyr.
+  Marginalizing over all parameters but Omega_0, the data favor Omega_0 \simeq
+0.9--1 (0.4--0.6) flat-Lambda (open) models. The range in deduced Omega_0
+values is partially a consequence of the different combinations of
+smaller-angular-scale CMB anisotropy data sets used in the analyses, but more
+significantly a consequence of whether the DMR quadrupole moment is accounted
+for or ignored in the analysis. For both flat-Lambda and open models, after
+marginalizing over all other parameters, a lower Omega_B h^2 \simeq
+0.005--0.009 is favored. This is also marginally at odds with estimates from
+more recent CMB anisotropy data and some estimates from standard
+nucleosynthesis theory and observed light element abundances. For both sets of
+models a younger universe with t_0 \simeq 12--15 Gyr is favored, consistent
+with other recent non-CMB indicators. We emphasize that since we consider only
+a small number of data sets, these results are tentative. More importantly, the
+analyses here do not rule out the currently favored flat-Lambda model with
+Omega_0 \sim 0.3, nor the larger Omega_B h^2 values favored by some other data.",0209567v1
+2003-01-10,The Microwave Anisotropy Probe (MAP) Mission,"The purpose of the MAP mission is to determine the geometry, content, and
+evolution of the universe via a 13 arcmin full-width-half-max (FWHM) resolution
+full sky map of the temperature anisotropy of the cosmic microwave background
+radiation with uncorrelated pixel noise, minimal systematic errors,
+multifrequency observations, and accurate calibration. These attributes were
+key factors in the success of NASA's Cosmic Background Explorer (COBE) mission,
+which made a 7 degree FWHM resolution full sky map, discovered temperature
+anisotropy, and characterized the fluctuations with two parameters, a power
+spectral index and a primordial amplitude. Following COBE considerable progress
+has been made in higher resolution measurements of the temperature anisotropy.
+With 45 times the sensitivity and 33 times the angular resolution of the COBE
+mission, MAP will vastly extend our knowledge of cosmology. MAP will measure
+the physics of the photon-baryon fluid at recombination. From this, MAP
+measurements will constrain models of structure formation, the geometry of the
+universe, and inflation. In this paper we present a pre-launch overview of the
+design and characteristics of the MAP mission. This information will be
+necessary for a full understanding of the MAP data and results, and will also
+be of interest to scientists involved in the design of future cosmic microwave
+background experiments and/or space science missions.",0301158v1
+2003-05-22,Scaling properties of the cosmic background plasma and radiation,"Scaling properties of the cosmic microwave background (CMB) radiation are
+studied using satellite (COBE-DMR maps), balloon-borne and ground-based
+(combined QMASK map) data. Quantitative consistency is found between the
+multiscaling properties of the COBE-DMR and QMASK CMB maps. Surprisingly, it is
+found that the observed CMB temperature multiscaling resembles quantitatively
+the multiscaling properties of fluid turbulence, that indicates primordial
+plasma turbulence as an origin of the CMB temperature space anisotropy.",0305433v1
+2003-05-30,The CAPMAP Instrument and its First Season,"I describe here the new CAPMAP (Cosmic Anisotropy Polarization MAPer)
+instrument, which performed its first season of observing between February and
+April 2003 from the Crawford Hill 7-meter antenna in NJ. CAPMAP is based on the
+design for the PIQUE instrument, but has better sensitivity and superior
+angular resolution.",0306002v1
+2003-07-31,An update on Archeops: flights and data products,"Archeops is a balloon-borne instrument dedicated to measuring CMB temperature
+anisotropies at high resolution over a large fraction of sky. We present the
+Archeops flights and data products, Archeops results, and the future use of
+Archeops data for multi-experiment data analysis.",0307550v1
+2003-07-31,"The Transverse Proximity Effect: A Probe to the Environment, Anisotropy, and Megayear Variability of QSOs","The transverse proximity effect is the expected decrease in the strength of
+the Lya forest absorption in a QSO spectrum when another QSO lying close to the
+line of sight enhances the photoionization rate above that due to the average
+cosmic ionizing background. We select three QSOs from the Early Data Release of
+the Sloan Digital Sky Survey that have nearby foreground QSOs, with proper line
+of sight tangential separations of 0.50, 0.82, and 1.10 h^{-1} Mpc. We estimate
+that the ionizing flux from the foreground QSO should increase the
+photoionization rate by a factor (94, 13, 13) in these three cases, which would
+be clearly detectable in the first QSO and marginally so in the other two. We
+do not detect the transverse proximity effect. Three possible explanations are
+provided: an increase of the gas density in the vicinity of QSOs, time
+variability, and anisotropy of the QSO emission. We find that the increase of
+gas density near QSOs can be important if they are located in the most massive
+halos present at high redshift, but is not enough to fully explain the absence
+of the transverse proximity effect. Anisotropy requires an unrealistically
+small opening angle of the QSO emission. Variability demands that the
+luminosity of the QSO with the largest predicted effect was much lower 10^6
+years ago, whereas the transverse proximity effect observed in the HeII Lya
+absorption in QSO 0302-003 by Jakobsen et al. (2003) implies a lifetime longer
+than 10^7 years. A combination of all three effects may better explain the lack
+of Lya absorption reduction. A larger sample of QSO pairs may be used to
+diagnose the environment, anisotropy and lifetime distribution of QSOs.",0307563v2
+2003-10-17,Multipole Vectors--a new representation of the CMB sky and evidence for statistical anisotropy or non-Gaussianity at 2<=l<=8,"We propose a novel representation of cosmic microwave anisotropy maps, where
+each multipole order l is represented by l unit vectors pointing in directions
+on the sky and an overall magnitude. These ""multipole vectors and scalars""
+transform as vectors under rotations. Like the usual spherical harmonics,
+multipole vectors form an irreducible representation of the proper rotation
+group SO(3). However, they are related to the familiar spherical harmonic
+coefficients, alm, in a nonlinear way, and are therefore sensitive to different
+aspects of the CMB anisotropy. Nevertheless, it is straightforward to determine
+the multipole vectors for a given CMB map and we present an algorithm to
+compute them. Using the WMAP full-sky maps, we perform several tests of the
+hypothesis that the CMB anisotropy is statistically isotropic and Gaussian
+random. We find that the result from comparing the oriented area of planes
+defined by these vectors between multipole pairs 2<=l1!=l2<=8 is inconsistent
+with the isotropic Gaussian hypothesis at the 99.4% level for the ILC map and
+at 98.9% level for the cleaned map of Tegmark et al. A particular correlation
+is suggested between the l=3 and l=8 multipoles, as well as several other
+pairs. This effect is entirely different from the now familiar planarity and
+alignment of the quadrupole and octupole: while the aforementioned is fairly
+unlikely, the multipole vectors indicate correlations not expected in Gaussian
+random skies that make them unusually likely. The result persists after
+accounting for pixel noise and after assuming a residual 10% dust contamination
+in the cleaned WMAP map. While the definitive analysis of these results will
+require more work, we hope that multipole vectors will become a valuable tool
+for various cosmological tests, in particular those of cosmic isotropy.",0310511v2
+2004-01-07,An updated nuclear reaction network for BBN,"The key Standard-Physics inputs of the Big Bang Nucleosynthesis (BBN) are the
+light nuclei reaction rates. Both the network and the nuclear rates have been
+recently reanalyzed and updated, and cosmological and New-Physics constraints
+(taking into account the WMAP Cosmic Microwave Background anisotropies
+measurement) obtained with a new code are presented.",0401072v1
+2004-03-31,Gradient measure and extended self-similarity of the cosmic microwave background anisotropy,"Using the WMAP cosmic microwave background data it is shown that collisions
+between Alfven wave packets and the cascades generated by these collisions (the
+Iroshnikov model) can determine the photon temperature fluctuations for
+arcminute scales on the last scattering surface.",0403702v2
+2004-04-27,Pre-inflation models and WMAP data,"The effect of pre-inflation physics on the power spectrum of scalar
+perturbations is estimated and there is a possibility that the pre-inflation
+physics explains the Wilkinson Microwave Anisotropy Probe data if the length of
+inflation is near 60 e-folds. Considering various pre-inflation models with
+radiation-dominated or matter-dominated periods before inflation, the power
+spectrum of curvature perturbations for large scales is calculated, and the
+spectral index and running spectral index are derived.",0404519v1
+2004-05-02,Low-order multipole maps of CMB anisotropy derived from WMAP,"Recent analyses of the WMAP data have suggested that the low-order multipoles
+of the CMB anisotropy distribution show cosmologically interesting and
+unexpected morphologies and amplitudes. In this paper, we apply a power
+equalization (PE) filter to the high-latitude WMAP data in order to reconstruct
+these low-l multipoles free from the largest Galactic foreground modelling
+uncertainties in the Galactic plane. The characteristic spatial distributions
+of the modes of order l=2,3,4,5 have been determined as a function of
+frequency, sky coverage and two methods for foreground correction: using the
+template fitting results of Bennett et al. (2003) and by a simple linear
+projection scheme assuming the spectral dependence of the foreground
+components. Our analyses suggest that the K and Ka frequency bands remain
+significantly contaminated by residual foreground emission for the WMAP Kp2
+mask. However, the l=3,4,5 multipole maps for the Q, V and W channels indicate
+that, after foreground cleaning, these multipoles are dominated by the CMB
+anisotropy component. We confirm the Tegmark et al. (2003) result that the
+octopole does indeed show structure in which its hot and cold spots are centred
+on a single plane in the sky, and show further that this is very stable with
+respect to the applied mask and foreground correction. The estimated quadrupole
+is much less stable showing non-negligible dependence on the Galactic
+foreground correction. Including these uncertainties is likely to weaken the
+statistical significance of the claimed alignment between the quadrupole and
+octopole. Nevertheless, these anisotropy patterns are also present for in
+COBE-DMR data, and are unlikely to be associated with instrumental systematic
+artifacts.",0405007v3
+2004-10-26,Inflation: Where Do We Stand?,"In this short review, the predictions of inflation are presented and compared
+to the most recent measurements of the Cosmic Microwave Background (CMB)
+anisotropy. It is argued that inflation is compatible with these observations
+but that these ones are not yet accurate enough to probe the details of the
+scenario.",0410629v1
+2004-11-02,High Redshift Intergalactic Medium: Probes and Physical Models,"Recent years have seen major advances in understanding the state of the
+intergalactic medium (IGM) at high redshift. Some aspects of this understanding
+are reviewed here. In particular, we discuss: (1) Different probes of IGM like
+Gunn-Peterson test, CMBR anisotropies, and neutral hydrogen emission from
+reionization, and (2) some models of reionization of the universe.",0411050v1
+2004-12-16,Can one hear the shape of the Universe?,"It is shown that the recent observations of NASA's explorer mission
+""Wilkinson Microwave Anisotropy Probe"" (WMAP) hint that our Universe may
+possess a non-trivial topology. As an example we discuss the Picard space which
+is stretched out into an infinitely long horn but with finite volume.",0412407v1
+2005-08-18,Going Nonlinear with Dark Energy Cosmologies,"We propose an efficient method for generating high accuracy (~1%) nonlinear
+power spectra for grids of dark energy cosmologies. Our prescription for
+matching matter growth automatically matches the main features of the cosmic
+microwave background anisotropy power spectrum, thus naturally including ``CMB
+priors''.",0508401v1
+2005-11-25,Mass distribution in nearby Abell clusters,"We study the mass distribution in six nearby (z<0.06) relaxed Abell clusters
+of galaxies A0262, A0496, A1060, A2199, A3158 and A3558. Given the dominance of
+dark matter in galaxy clusters we approximate their total density distribution
+by the NFW formula characterized by virial mass and concentration. We also
+assume that the anisotropy of galactic orbits is reasonably well described by a
+constant and that galaxy distribution traces that of the total density. Using
+the velocity and position data for 120-420 galaxies per cluster we calculate,
+after removal of interlopers, the profiles of the lowest-order even velocity
+moments, dispersion and kurtosis. We then reproduce the velocity moments by
+jointly fitting the moments to the solutions of the Jeans equations. Including
+the kurtosis in the analysis allows us to break the degeneracy between the mass
+distribution and anisotropy and constrain the anisotropy as well as the virial
+mass and concentration. The method is tested in detail on mock data extracted
+from N-body simulations of dark matter haloes. We find that the best-fitting
+galactic orbits are remarkably close to isotropic in most clusters. Using the
+fitted pairs of mass and concentration parameters for the six clusters we
+conclude that the trend of decreasing concentration for higher masses found in
+cosmological N-body simulations is consistent with the data. By scaling the
+individual cluster data by mass we combine them to create a composite cluster
+with 1465 galaxies and perform a similar analysis on such sample. The estimated
+concentration parameter then lies in the range 1.5 < c < 14 and the anisotropy
+parameter in the range -1.1 < \beta < 0.5 at the 95 percent confidence level.",0511723v2
+2005-12-08,Anisotropy of the cosmic gamma-ray background from dark matter annihilation,"High-energy photons from dark matter annihilation contribute to the cosmic
+gamma-ray background (CGB). Since dark matter particles are weakly interacting,
+annihilation can happen only in high density regions such as dark matter halos.
+The precise shape of the energy spectrum of CGB depends on the nature of dark
+matter particles, as well as the cosmological evolution of dark matter halos.
+In order to discriminate between the signals from dark matter annihilation and
+other astrophysical sources, however, the information from the energy spectrum
+may not be sufficient. We show that dark matter annihilation also produces a
+characteristic anisotropy of the CGB, which provides a powerful tool for
+testing the origin. We develop the formalism based on a halo model approach to
+calculate the three-dimensional power spectrum of dark matter clumping, which
+determines the power spectrum of annihilation signals. We show that the
+sensitivity of future gamma-ray detectors such as GLAST should allow us to
+measure the angular power spectrum of CGB anisotropy, if dark matter particles
+are supersymmetric neutralinos and they account for most of the observed mean
+intensity of CGB in GeV region. On the other hand, if dark matter has a
+relatively small mass, and accounts for most of the CGB in MeV region, then the
+future Advanced Compton Telescope should be able to measure the anisotropy in
+MeV region. As the intensity of photons from annihilation is proportional to
+the density squared, we show that the predicted shape of the angular power
+spectrum of gamma rays from dark matter annihilation is different from that due
+to other astrophysical sources such as blazars. Therefore, the angular power
+spectrum of the CGB provides a smoking-gun signature of dark matter
+annihilation.",0512217v2
+2006-05-26,Cosmological and Astrophysical Parameter Measurements with 21-cm Anisotropies During the Era of Reionization,"We study the prospects for extracting cosmological and astrophysical
+parameters from the low radio frequency 21-cm background due to the spin-flip
+transition of neutral Hydrogen during and prior to the reionization of the
+Universe. We make use of the angular power spectrum of 21-cm anisotropies,
+which exists due to inhomogeneities in the neutral Hydrogen density field, the
+gas temperature field, the gas velocity field, and the spatial distribution of
+the Lyman-$\alpha$ intensity field associated with first luminous sources that
+emit UV photons. We extract parameters that describe both the underlying mass
+power spectrum and the global cosmology, as well as a set of simplified
+astrophysical parameters that connect fluctuations in the dark matter to those
+that govern 21-cm fluctuations. We also marginalize over a model for the
+foregrounds at low radio frequencies. In this general description, we find
+large degeneracies between cosmological parameters and the astrophysical
+parameters, though such degeneracies are reduced when strong assumptions are
+made with respect to the spin temperature relative to the CMB temperature or
+when complicated sources of anisotropy in the brightness temperature are
+ignored. Some of the degeneracies between cosmological and astrophysical
+parameters are broken when 21-cm anisotropy measurements are combined with
+information from the CMB, such as the temperature and the polarization
+measurements with Planck. While the overall improvement on the cosmological
+parameter estimates is not significant when measurements from first-generation
+interferometers are combined with Planck, such a combination can measure
+astrophysical parameters such as the ionization fraction in several redshift
+bins with reasonable accuracy.",0605677v3
+2006-10-31,Open questions with ultra-high energy cosmic rays,"We briefly discuss three aspects related to the origin of ultra-high energy
+cosmic rays (UHECRs) namely: 1) particle acceleration in astrophysical sources;
+2) transition to an extragalactic origin; 3) spectrum and anisotropies at the
+highest energies.",0610951v1
+2006-11-07,Improved Measurements of the CMB Power Spectrum with ACBAR,"We report improved measurements of temperature anisotropies in the cosmic
+microwave background (CMB) radiation made with the Arcminute Cosmology
+Bolometer Array Receiver (ACBAR). In this paper, we use a new analysis
+technique and include 30% more data from the 2001 and 2002 observing seasons
+than the first release to derive a new set of band-power measurements with
+significantly smaller uncertainties. The planet-based calibration used
+previously has been replaced by comparing the flux of RCW38 as measured by
+ACBAR and BOOMERANG to transfer the WMAP-based BOOMERANG calibration to ACBAR.
+The resulting power spectrum is consistent with the theoretical predictions for
+a spatially flat, dark energy dominated LCDM cosmology including the effects of
+gravitational lensing. Despite the exponential damping on small angular scales,
+the primary CMB fluctuations are detected with a signal-to-noise ratio of
+greater than 4 up to multipoles of l=2000. This increase in the precision of
+the fine-scale CMB power spectrum leads to only a modest decrease in the
+uncertainties on the parameters of the standard cosmological model. At high
+angular resolution, secondary anisotropies are predicted to be a significant
+contribution to the measured anisotropy. A joint analysis of the ACBAR results
+at 150 GHz and the CBI results at 30 GHz in the multipole range 2000 < l < 3000
+shows that the power, reported by CBI in excess of the predicted primary
+anisotropy, has a frequency spectrum consistent with the thermal
+Sunyaev-Zel'dovich effect and inconsistent with primary CMB. The results
+reported here are derived from a subset of the total ACBAR data set; the final
+ACBAR power spectrum at 150 GHz will include 3.7 times more effective
+integration time and 6.5 times more sky coverage than is used here.",0611198v1
+1993-08-01,Variational bound for the energy of two-dimensional quantum antiferromagnet,"We obtain the variational upper bound for the ground- state energy of
+two-dimensional antiferromagnetic Heisenberg model on a square lattice at
+arbitrary value of the anisotropy parameter using the two-dimensional
+generalization of Jordan-Wigner transformation. Our result can be considered as
+an upper bound for the perturbation theory series about the Ising limit.",9307067v1
+1995-04-24,An Upsilon Point in a Spin Model,"We present analytic evidence for the occurrence of an upsilon point, an
+infinite checkerboard structure of modulated phases, in the ground state of a
+spin model. The structure of the upsilon point is studied by calculating
+interface--interface interactions using an expansion in inverse spin
+anisotropy.",9504093v1
+1995-06-29,Theory of Nuclear Magnetic Relaxation in Haldane Gap Antiferromagnets,"A theory of Nuclear Magnetic Resonance (NMR) is developed for integer-spin,
+one-dimensional antiferromagnets, which exhibit the Haldane gap. We consider
+free boson, free fermion and non-linear sigma model approaches, all of which
+give similar results. Detailed anisotropy and magnetic field dependence is
+calculated and compared with experiment.",9506137v3
+1995-10-01,Ultrasound attenuation in gap-anisotropic systems,"Transverse ultrasound attenuation provides a weakly-coupled probe of momentum
+current correlations in electronic systems. We develop a simple theory for the
+interpretation of transverse ultrasound attenuation coefficients in systems
+with nodal gap anisotropy. Applying this theory we show how ultrasound can
+delineate between extended-s and d-wave scenarios for the cuprate
+superconductors.",9509177v2
+1996-10-01,Generalized London free energy for high-$T_c$ vortex lattices,"We generalize the London free energy to include four-fold anisotropies which
+could arise from d-wave pairing or other sources in a tetragonal material. We
+use this simple model to study vortex lattice structure and discuss neutron
+scattering, STM, Bitter decoration and $\mu$SR experiments.",9610006v1
+1996-10-30,Fermi Surface of the 2D Hubbard Model at Weak Coupling,"We calculate the interaction-induced deformation of the Fermi surface in the
+two-dimensional Hubbard model within second order perturbation theory. Close to
+half-filling, interactions enhance anisotropies of the Fermi surface, but they
+never modify the topology of the Fermi surface in the weak coupling regime.",9610216v2
+1996-12-03,The Critical Temperature of an Anisotropic Superconductor in the Presence of a Homogeneous Magnetic Field and Impurities,"The effect of a homogeneous magnetic field and nonmagnetic impurities on the
+critical temperature of an anisotropic superconductor has been investigated.
+The role of these pair-breakers in relation to the anisotropy of the order
+parameter is clarified.",9612030v1
+1997-03-12,Only Fermi-Liquids are Metals,"Any singular deviation from Landau Fermi-liquid theory appears to lead, for
+arbitrarily small concentration of impurities coupling to a non-conserved
+quantity, to a vanishing density of states at the chemical potential and
+infinite resistivity as temperature approaches zero. Applications to
+copper-oxide metals including the temperature dependence of the anisotropy in
+resistivity, and to other cases of non Fermi-liquids are discussed.",9703122v1
+1997-09-13,Spin-density Wave in Ising-coupled Antiferromagnetic Chains,"The effect of anisotropy in the nearest-neighbor spin interactions that
+couple $N\geq 2$ consecutive spin-1/2 antiferromagnetic chains is studied
+theoretically by considering the limit where the coupling is purely of the
+Ising type. An analysis based on the equivalent Luttinger model reveals that
+the groundstate is an Ising antiferromagnet in general.",9709153v1
+1998-02-04,Exact Correlation Amplitude for the S=1/2 Heisenberg Antiferromagnetic Chain,"The exact amplitude for the asymptotic correlation function in the S=1/2
+Heisenberg antiferromagnetic chain is determined: <S^a_0 S^b_r> goes to (-1)^r
+delta^{ab}(ln r)^{1/2}/[(2 pi)^{3/2}r]. The behaviour of the correlation
+functions for small xxz anisotropy and the form of finite-size corrections to
+the correlation function are also analysed.",9802045v2
+1998-07-14,Non-equilibrium critical behavior of O(n)-symmetric systems: Effect of reversible mode-coupling terms and dynamical anisotropy,"Phase transitions in non-equilibrium steady states of O(n)-symmetric models
+with reversible mode couplings are studied using dynamic field theory and the
+renormalization group. The systems are driven out of equilibrium by dynamical
+anisotropy in the noise for the conserved quantities, i.e., by constraining
+their diffusive dynamics to be at different temperatures T^\par and T^\perp in
+d_\par- and d_\perp-dimensional subspaces, respectively. In the case of the
+Sasv'ari-Schwabl-Sz'epfalusy (SSS) model for planar ferro- and isotropic
+antiferromagnets, we assume a dynamical anisotropy in the noise for the
+non-critical conserved quantities that are dynamically coupled to the
+non-conserved order parameter. We find the equilibrium fixed point (with
+isotropic noise) to be stable with respect to these non-equilibrium
+perturbations, and the familiar equilibrium exponents therefore describe the
+asymptotic static and dynamic critical behavior. Novel critical features are
+only found in extreme limits, where the ratio of the effective noise
+temperatures T^\par/T^\perp is either zero or infinite. On the other hand, for
+model J for isotropic ferromagnets with a conserved order parameter, the
+dynamical noise anisotropy induces effective long-range elastic forces, which
+lead to a softening only of the d_\perp-dimensional sector in wavevector space
+with lower noise temperature T^\perp < T^\par. The ensuing static and dynamic
+critical behavior is described by power laws of a hitherto unidentified
+universality class, which, however, is not accessible by perturbational means
+for d_\par \geq 1. We obtain formal expressions for the novel critical
+exponents in a double expansion about the static and dynamic upper critical
+dimensions and d_\par, i.e., about the equilibrium theory.",9807207v2
+1998-10-21,Competition of Ferromagnetic and Antiferromagnetic Order in the Spin-1/2 XXZ Chain at Finite Temperature,"An analytical study is presented of the crossover in the gapless attractive
+XXZ chain from antiferromagnetic to ferromagnetic behaviour at low to high
+temperature, respectively. In particular, an analytic formula for the crossover
+in the long distance asymptotics and explicit results for the nearest-neighbour
+longitudinal correlation are obtained. We also provide results for the specific
+heat and magnetic susceptibility for various anisotropies.",9810278v1
+1999-01-08,Solidity of viscous liquids II: Anisotropic flow events,"Recent findings on the displacements in the surroundings of isotropic flow
+events in viscous liquids [Phys. Rev. E, to appear Feb. 1999] are generalized
+to the anisotropic case. Also, it is shown that a flow event is characterized
+by a dimensionless number reflecting the degree of anisotropy.",9901061v1
+1999-10-14,Magnetic field induced directional localization in a 2D rectangular lattice,"We study the effect of a perpendicular uniform magnetic field on the
+dissipative conductivity of a rectangular lattice with anisotropic hopping,
+$t_x\neq t_y $. We show that the magnetic field may enhance dramatically the
+directional anisotropy in the conductivity. The effect is a measurable physical
+realization of Aubry's duality in Harper systems.",9910209v1
+1999-12-07,Impurity Scattering in f-wave Superconductor UPt_3,"We study theoretically the effect of impurity scattering in f-wave (or
+E_{2u}) superconductors. The quasi-particle density of states of f-wave
+superconductor is very similar to the one for d-wave superconductor as in
+hole-doped high T_c cuprates. Also in spite of anisotropy in Delta(k), both the
+normalized superfluid density and the thermal conductivity is completely
+isotropic.",9912124v1
+2000-02-28,The puzzle of 90 degree reorientation in the vortex lattice of borocarbide superconductors,"We explain 90 degree reorientation in the vortex lattice of borocarbide
+superconductors on the basis of a phenomenological extension of the nonlocal
+London model that takes full account of the symmetry of the system. We propose
+microscopic mechanisms that could generate the correction terms and point out
+the important role of the superconducting gap anisotropy.",0002431v1
+2000-04-24,Vector lattice model for stresses in granular materials,"A vector lattice model for stresses in granular materials is proposed. A two
+dimensional pile built by pouring from a point is constructed numerically
+according to this model. Remarkably, the pile violates the Mohr Coulomb
+stability criterion for granular matter, probably because of the inherent
+anisotropy of such poured piles. The numerical results are also compared to the
+earlier continuum FPA model and the (scalar) lattice $q$-model.",0004399v1
+2000-05-13,Restoration of Macroscopic Isotropy on $(d+1)$-Simplex Fractal Conductor Networks,"Restoration of macroscopic isotropy has been investigated in (d+1)-simplex
+fractal conductor networks via exact real space renormalization group
+transformations. Using some theorems of fixed point theory, it has been shown
+very rigoroursly that the macroscopic conductivity becomes isotropic for large
+scales and anisotropy vanishes with a scaling exponent which is computed
+exactly for arbitrary values of d and decimation numbers b=2,3,4 and
+  5.",0005227v1
+2001-01-04,Finite Size Scaling of the 2D Six-Clock model,"We investigate the isotropic-anisotropic phase transition of the
+two-dimensional XY model with six-fold anisotropy, using Monte Carlo
+renormalization group method. The result indicates difficulty of observing
+asymptotic critical behavior in Monte Carlo simulations, owing to the marginal
+flow at the fixed point.",0101035v1
+2001-01-04,Coulomb effects in dynamics of polar lattices,"Zone-center phonon frequencies of polar lattices are calculated for uniaxial
+crystals from the symmetry arguments. Long-range Coulomb forces and crystal
+anisotropy are explicitly taken into account. Free-carrier contributions into a
+dielectric constant are included. The angular dispersion of optical-phonon
+modes is compared with data for hexagonal 6H-SiC politype.",0101050v1
+2002-01-16,A Model for Granular Texture with Steric Exclusion,"We propose a new method to characterize the geometrical texture of a granular
+packing at the particle scale including the steric hindrance effect. This
+method is based on the assumption of a maximum disorder (entropy) compatible
+both with strain-induced anisotropy of the contact network and steric
+exclusions. We show that the predicted statistics for the local configurations
+is in a fairly agreement with our numerical data.",0201275v1
+2002-03-03,Symmetry Properties of Anisotropic Superfluids,"A system of equations is developed for a fluid with non-abelian local gauge
+symmetry. Anisotropy is introduced by requiring that the symmetry breaking
+preserves a restricted local gauge symmetry about a given direction in the
+gauge parameter space. A set of equations is proposed for the 3He-A system.
+Topological quantization conditions are discussed.",0203045v1
+2002-04-01,Ground-State Phase Diagram of Frustrated Anisotropic Quantum Spin Chains,"Recent studies on the frustrated quantum spin chains with easy-plane
+anisotropy are reviewed. We are particularly interested in novel ""chiral""
+phases characterized by the spontaneous breaking of the parity symmetry. The
+ground-state phase diagrams of the chains are discussed.",0204022v1
+2002-05-13,Critical behavior of vector models with cubic symmetry,"We report on some results concerning the effects of cubic anisotropy and
+quenched uncorrelated impurities on multicomponent spin models. The analysis of
+the six-loop three-dimensional series provides an accurate description of the
+renormalization-group flow.",0205251v1
+2002-10-24,Competing interactions in the XYZ model,"We study the interplay between a XY anisotropy $\gamma$, exchange modulations
+and an external magnetic field along the z direction in the XYZ chain using
+bosonization and Lanczos diagonalization techniques. We find an Ising critical
+line in the space of couplings which occur due to competing relevant
+perturbations which are present. More general situations are also discussed.",0210546v1
+2003-03-19,A new class of nodal stationary states in 2D Heisenberg ferromagnet,"A new class of nodal topological excitations in a two-dimensional Heisenberg
+model is studied. The solutions correspond to a nodal singular point of the
+gradient field of the azimuthal angle. An analytical solution found for the
+isotropic case. An effect of in-plane exchange anisotropy is studied
+numerically. It results in solutions which are analogues of the conventional
+out-of-plane solitons in the two-dimensional magnets.",0303388v1
+2003-04-18,Superradiation from Crystals of High-Spin Molecular Nanomagnets,"Phenomenological theory of superradiation from crystals of high-spin
+molecules is suggested. We show that radiation friction can cause a
+superradiation pulse and investigate the role of magnetic anisotropy, external
+magnetic field and dipole-dipole interactions. Depending on the contribution of
+all these factors at low temperature, several regimes of magnetization of
+crystal sample are described. Very fast switch of magnetization's direction for
+some sets of parameters is predicted.",0304424v1
+2003-07-17,Local density of states induced by anisotropic impurity scattering in a d-wave superconductor,"We study a single impurity effect on the local density of states in a d-wave
+superconductor accounting for the momentum-dependent impurity potential. We
+show that the anisotropy of the scattering potential can alter significantly
+the spatial dependence of the quasiparticle density of states in the vicinity
+of the impurity.",0307427v1
+2003-09-28,Liquid Crystals in Electric Field,"We present a general theory of electric field effects in liquid crystals
+where the dielectric tensor depends on the orientation order. As applications,
+we examine (i) the director fluctuations in nematic states in electric field
+for arbitrary strength of the dielectric anisotropy and (ii) deformation of the
+nematic order around a charged particle. Some predictions are made for these
+effects.",0309643v1
+2004-03-31,1D Exciton Spectroscopy of Semiconductor Nanorods,"We have theoretically shown that optical properties of semiconductor nanorods
+are controlled by 1D excitons. The theory, which takes into account anisotropy
+of spacial and dielectric confinement, describes size dependence of interband
+optical transitions, exciton binding energies. We have demonstrated that the
+fine structure of the ground exciton state explains the linear polarization of
+photoluminescence. Our results are in good agreement with the measurements in
+CdSe nanorods.",0403768v1
+2004-04-14,On the theory of pseudogap anisotropy in the cuprate superconductors,"We show by means of the theory of the order parameter phase fluctuations that
+the temperature of ""closing"" (or ""opening"") of the gap (and pseudogap) in the
+electron spectra of superconductors with anisotropic order parameter takes
+place within a finite temperature range. Every Fourier-component of the order
+parameter has its own critical temperature.",0404335v3
+2004-05-18,Multichannel field-effect spin barrier selector,"We have studied spin carrier dynamics under full spin-orbit coupling. The
+anisotropy of dispersions for independent circular spinor polarizations is
+explored as a possible vertical multichannel voltage controlled spin-filter.
+Small voltage variations are found to select the current polarizations in a
+resonant tunneling geometry.",0405418v1
+2004-05-29,Anomalous interaction between vortices and nanomagnets,"We study a thin film system consisting of a superconducting and a magnetic
+film, where the superconductor contains a vortex and the magnetic film a
+nanomagnet. We find that if the magnetic film has planar anisotropy, the vortex
+induces a magnetization distribution, and its interaction with the nanomagnet
+crosses over from attractive to repulsive at short distances.",0405690v1
+2004-09-27,Electronic Structure and Magnetic Properties of Solids,"We review basic computational techniques for simulations of various magnetic
+properties of solids. Several applications to compute magnetic anisotropy
+energy, spin wave spectra, magnetic susceptibilities and temperature dependent
+magnetisations for a number of real systems are presented for illustrative
+purposes.",0409704v1
+2004-10-06,Superconductivity of Magnesium Diboride: Theoretical Aspects,"In this work we review our present understanding of superconductivity in
+Magnesium Diboride from the theoretical perspective as it evolves from band
+structure calculations. Particular emphasis is placed on two gap
+superconductivity. Some of its peculiar consequences are discussed, in
+particular upper critical field anisotropy and microwave conductivity.",0410158v1
+2004-12-15,Elastic medium confined in a column versus the Janssen experiment,"We compute the stresses in an elastic medium confined in a vertical column,
+when the material is at the Coulomb threshold everywhere at the walls.
+Simulations are performed in 2 dimensions using a spring lattice, and in 3
+dimensions, using Finite Element Method. The results are compared to the
+Janssen model and to experimental results for a granular material. The
+necessity to consider elastic anisotropy to render qualitatively the
+experimental findings is discussed.",0412400v1
+2005-03-02,Quantum shape effects on Zeeman splittings in semiconductor nanostructures,"We develop a general method to calculate Zeeman splittings of electrons and
+holes in semiconductor nanostructures within the tight-binding framework. The
+calculation is carried out in the electron-hole picture and is extensible to
+the excitonic calculation by including the electron-hole Coulomb interaction.
+The method is suitable for the investigation of quantum shape effects and the
+anisotropy of the g-factors. Numerical results for CdSe and CdTe nanostructures
+are presented.",0503042v1
+2005-03-14,Carbon-doped high mobility two-dimensional hole gases on (110) faced GaAs,"Carbon-doped high mobility two-dimensional hole gases grown on (110) oriented
+GaAs substrates have been grown with hole mobilities exceeding 10^6 cm^2/Vs in
+single heterojunction GaAs/AlGaAs structures. At these high mobilities, a
+pronounced mobility anisotropy has been observed. Rashba induced spin-splitting
+in these asymmetric structures has been found to be independent on the
+transport direction.",0503323v1
+2005-04-28,To the theory of interaction between electron and nuclear systems,"Coupled electron-nuclear oscillations in antiferromagnetics with anisotropy
+of ""light plane"" type in the strong external magnetic field are under
+consideration. The new mode \epsilon_{2k} of these coupled oscillations is
+obtained for antiferromagnetic systems by using ""u-v""-Bogolubov?s unitary
+transformations. The dynamic shift of the frequency of nuclear magnetic
+resonance concerned with this mode is obtained.",0504759v1
+2006-02-21,Magnetic-induced phonon anisotropy in ZnCr$_2$O$_4$ from first principles,"We have studied the influence of magnetic order on the optical phonons of the
+geometrically frustrated spinel ZnCr$_2$O$_4$ from first-principles. By mapping
+the first-principles phonon calculations onto a Heisenberg-like model, we
+developed a method to calculate exchange derivatives and subsequently the
+spin-phonon couping parameter from first-principles. All calculations were
+performed within LSDA+U.",0602503v1
+2006-08-22,Simulation of stress-impedance effects in low magnetostrictive films,"A theoretical study of stress-impedance effect based on the solution of
+Landau-Lifsitz-Gilbert equation has been carried out. The results show that
+stress impedance effects depend largely on several extrinsic (external bias
+field, external frequency) and intrinsic (orientation and magnitude of uniaxial
+anisotropy, damping) parameters.",0608488v1
+2006-10-09,On the occurrence of Kosterlitz-Thouless behavior in cuprate superconductors,"The observation of the characteristic Kosterlitz-Thouless behavior requires
+the attaintment of the two dimensional limit where the correlation-length
+anisotropy, gamma=gsiab/gsic, diverges. Our findings strongly suggest that the
+failure of several experiments on films and single crystals to observe any
+trace of KT-behavior is attributable either to inhomogeneities or doping by
+means of chemical substitution.",0610230v1
+2007-02-06,Finite-size effects for anisotropic bootstrap percolation: logarithmic corrections,"In this note we analyze an anisotropic, two-dimensional bootstrap percolation
+model introduced by Gravner and Griffeath. We present upper and lower bounds on
+the finite-size effects. We discuss the similarities with the semi-oriented
+model introduced by Duarte.",0702145v1
+1993-04-14,Relic Gravitational Waves and Limits on Inflation,"It is shown that only a narrow class of inflationary models can possibly
+agree with the available observational data on the anisotropy of the cosmic
+microwave background radiation (CMBR). These models may be governed by
+``matter'' with the effective equation of state $-1.2 <p/ \epsilon < -0.6$
+which includes the De-Sitter case $p/ \epsilon = -1$.",9304018v1
+1995-11-15,Quadrupole anisotropy from photon quantum effects,"We consider quantum effects of an electromagnetic field in a
+radiation-dominated almost FRW spacetime. The dominant non-local quantum
+correction to the photon distribution is a quadrupole moment, corresponding to
+an effective anisotropic pressure in the energy-momentum tensor.",9511044v1
+1997-04-16,Constraints on Space-Time Torsion from Hughes-Drever Experiments,"The coupling of space-time torsion to the Dirac equation leads to effects on
+the energy levels of atoms which can be tested by Hughes-Drever type
+experiments. Reanalysis of these experiments carried out for testing the
+anisotropy of mass and anomalous spin couplings can lead to the till now
+tightest constraint on the axial torsion by $K \leq 1.5 . 10^{-15} m^{-1}$.",9704047v1
+1999-12-20,Anisotropic 'hairs' in string cosmology,"In this letter we investigate whether the isotropy problem is naturally
+solved in inflationary cosmologies inspired by string theory, so called
+pre-big-bang cosmologies. We find that, in contrast to what happens in the more
+common 'potential inflation' models, initial anisotropies do not decay during
+pre-big-bang inflation.",9912081v1
+2000-01-20,Stochastic Processes and Thermodynamics on Curved Spaces,"Our approach views the thermodynamics and kinetics in general relativity and
+extended gravitational theories (with generic local anisotropy) from the
+perspective of the theory of stochastic differential equations on curved
+spaces.
+  Nonequilibrium and irreversible processes in black hole thermodynamics are
+considered. The paper summarizes the author's contribution to Journees
+Relativistes 99 (12--17 September 1999), Weimar, Germany.",0001057v1
+2002-03-24,A Geometric Anisotropic Model of Space-Time Based on Finsler Metric,"In this work we study an anisotropic model of general relativity based on the
+framework of Finsler geometry. The observed anisotropy of the microwave
+background radiation is incorporated in the Finslerian structure of space-time.
+We also examine the electromagnetic (e.m.) field equations in our space. As a
+result a modified wave equation of e.m. waves yields.",0203083v1
+2002-07-24,Finslerian Extension of Lorentz Transformations and First-Order Censorship Theorem,"Granted the post-Lorentzian relativistic kinematic transformations are
+described in the Finslerian framework, the uniformity between the actual light
+velocity anisotropy change and the anisotropic deformation of measuring rods
+can be the reason proper for the null results of the Michelson-Morley-type
+experiments at the first-order level.",0207089v1
+2000-10-17,Can One Study Heavy Meson Semileptonic Decays on Coarse Anisotropic Lattices ?,"Exploratory studies of heavy meson semileptonic decays on coarse lattices
+using Symanzik improved glue, NRQCD heavy and D234 light quarks are discussed.
+Comparisons are made between calculations on anisotropic and isotropic
+lattices. We find evidence that having an anisotropy helps in extracting better
+signals at higher momenta.",0010029v1
+2001-10-26,Relativistic bottomonium spectrum from anisotropic lattices,"We report on our results from a fully relativistic simulation of the quenched
+bottomonium spectrum. Using an anisotropic formulation of Lattice QCD, we were
+able to retain a very fine resolution into the temporal direction for a range
+of different lattice spacings. At fixed renormalized anisotropy we study the
+scaling properties of the spectrum and compare our results with
+non-relativistic calculations.",0110207v1
+2001-12-03,Asymptotic freedom with discrete spin variables?,"We study the critical behaviour of the 2d dodecahedron spin model and
+investigate the conjecture that the discrete model describes the same continuum
+theory as the O(3) non-linear sigma model. In particular, we found that the
+anisotropy of the magnetization A(z) measured in a fixed physical volume
+decreases with increasing correlation length, at least up to \xi \approx 1000.",0112003v1
+2003-09-16,Brane World Moduli and the CMB,"The evolution of moduli fields, which naturally appear in higher dimensional
+models such as brane worlds, and their effects on the anisotropies of the
+cosmological microwave background radiation is discussed.",0309181v1
+2003-09-19,Status of observational cosmology and inflation,"We review the latest developments in the determination of the cosmological
+parameters from the measurement of the Cosmic Microwave Background Radiation
+(CMBR) anisotropies and of the Large Scale Structure (LSS) of the Universe. We
+comment finally on the implications for the primordial spectrum and the
+consequences for inflationary models.",0309238v1
+2004-07-09,Modern Cosmology,"I review in these lectures our present understanding of the origin and
+evolution of the universe, making emphasis on the most recent observations of
+the acceleration of the universe, the precise measurements of the microwave
+background anisotropies, and the formation of structure like galaxies and
+clusters of galaxies from tiny primodial fluctuations generated during
+inflation.",0407111v1
+2001-11-26,Integrable XYZ Model with Staggered Anisotropy Parameter,"We apply to the XYZ model the technique of construction of integrable models
+with staggered parameters, presented recently for the XXZ case. The solution of
+modified Yang-Baxter equations is found and the corresponding integrable
+zig-zag ladder Hamiltonian is calculated. The result is coinciding with the XXZ
+case in the appropriate limit.",0111233v1
+2002-01-17,Emptiness formation probability of the XXZ spin-1/2 Heisenberg chain at Delta=1/2,"Using a multiple integral representation for the correlation functions, we
+compute the emptiness formation probability of the XXZ spin-1/2 Heisenberg
+chain at anisotropy Delta=1/2. We prove it is expressed in term of the number
+of alternating sign matrices.",0201134v1
+2002-10-09,Multi-leg integrable ladder models,"We construct integrable spin chains with inhomogeneous periodic disposition
+of the anisotropy parameter. The periodicity holds for both auxiliary (space)
+and quantum (time) directions. The integrability of the model is based on a set
+of coupled Yang-Baxter equations. This construction yields P-leg integrable
+ladder Hamiltonians. We analyse the corresponding quantum group symmetry.",0210087v1
+2005-03-21,Super-horizon Perturbations and CMBA,"We provided a gedanken experiment and argued that since observers inside a
+given Hubble volume could not detect the super horizon perturbation modes as
+real perturbations, these modes could only affect the average value of the
+cosmic microwave background (CMB), but not its anisotropy properties (CMBA) in
+that Hubble volume.",0503154v1
+2001-10-26,Locating anisotropies in electrical impedance tomography,"In this article, we consider the problem of finding the support of an
+inhomogenous possibly anisotropic inclusion in a background of constant
+electric conductivity from the electrical impedance tomography data at the
+boundary of a bounded body. The article discusses the linear sampling method
+applied to this problem. A practical algorithm for solving this problem is
+suggested.",0110299v1
+2006-05-09,Measuring Large Scale Space Perception in Literary Texts,"The center and radius of perception associated with a written text are
+defined, and algorithms for their computation are presented. Indicators for
+anisotropy in large scale space perception are introduced. The relevance of
+these notions for the analysis of literary and historical records is briefly
+discussed and illustrated with an example taken from medieval historiography.",0605224v1
+2006-05-18,Adaptive multiscale detection of filamentary structures in a background of uniform random points,"We are given a set of $n$ points that might be uniformly distributed in the
+unit square $[0,1]^2$. We wish to test whether the set, although mostly
+consisting of uniformly scattered points, also contains a small fraction of
+points sampled from some (a priori unknown) curve with $C^{\alpha}$-norm
+bounded by $\beta$. An asymptotic detection threshold exists in this problem;
+for a constant $T_-(\alpha,\beta)>0$, if the number of points sampled from the
+curve is smaller than $T_-(\alpha,\beta)n^{1/(1+\alpha)}$, reliable detection
+is not possible for large $n$. We describe a multiscale significant-runs
+algorithm that can reliably detect concentration of data near a smooth curve,
+without knowing the smoothness information $\alpha$ or $\beta$ in advance,
+provided that the number of points on the curve exceeds
+$T_*(\alpha,\beta)n^{1/(1+\alpha)}$. This algorithm therefore has an optimal
+detection threshold, up to a factor $T_*/T_-$. At the heart of our approach is
+an analysis of the data by counting membership in multiscale multianisotropic
+strips. The strips will have area $2/n$ and exhibit a variety of lengths,
+orientations and anisotropies. The strips are partitioned into anisotropy
+classes; each class is organized as a directed graph whose vertices all are
+strips of the same anisotropy and whose edges link such strips to their ``good
+continuations.'' The point-cloud data are reduced to counts that measure
+membership in strips. Each anisotropy graph is reduced to a subgraph that
+consist of strips with significant counts. The algorithm rejects $\mathbf{H}_0$
+whenever some such subgraph contains a path that connects many consecutive
+significant counts.",0605513v1
+2002-01-11,Symmetric Periodic Solutions of the Anisotropic Manev Problem,"We consider the Manev Potential in an anisotropic space, i.e., such that the
+force acts differently in each direction. Using a generalization of the
+  Poincare' continuation method we study the existence of periodic solutions
+for weak anisotropy. In particular we find that the symmetric periodic orbits
+of the Manev system are perturbed to periodic orbits in the anisotropic
+problem.",0201018v1
+2002-12-18,Tip Oscillation of Dendritic Patterns in a Phase Field Model,"We study dendritic growth numerically with a phase field model. Tip
+oscillation and regular side-branching are observed in a parameter region where
+the anisotropies of the surface tension and the kinetic effect compete. The
+transition from a needle pattern to a dendritic pattern is conjectured to be a
+supercritical Hopf bifurcation.",0212040v1
+2002-11-27,"Correlations, Fluctuations, and Flow Measurements from the STAR Experiment","New measurements of short-range and long-range two-particle correlations,
+azimuthal anisotropy, and event-by-event fluctuations from the STAR experiment
+for sqrt{s_{NN}}= 130 and 200 GeV Au+Au collisions are summarized. Striking
+evidence is presented for large, non-statistical fluctuations in mean
+transverse momentum. Descriptions of the data in terms of phenomenological
+source function models are also presented.",0211030v1
+2004-03-12,Azimuthal anisotropy: the higher harmonics,"We report the first observations of the fourth harmonic (v_4) in the
+azimuthal distribution of particles at RHIC. The measurement was done taking
+advantage of the large elliptic flow generated at RHIC. The integrated v_4 is
+about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
+harmonics upper limits on the magnitudes are reported.",0403019v1
+1994-02-22,Fission fragment orientation and gamma ray emission anisotropy,"Experimental data on angular distributions of gamma rays emitted from binary
+and ternary spontaneous fission of $^{252}{\rm Cf}$ are analyzed. Their
+difference indicates that the alignment of fragments is higher in ternary
+fission than in binary one. The consequences of possible relation between the
+mechanism of ternary fission and the excitation of collective modes during the
+saddle-to-scission stage are discussed.",9402024v1
+1996-11-19,Transverse Radial Expansion and Directed Flow,"The effects of an interplay of radial expansion of the thermalized system
+created in a heavy ion collision and directed flow are discussed. It is shown
+that the study of azimuthal anisotropy of particle distribution as a function
+of rapidity and transverse momentum could reveal important information on both
+radial and directed flow.",9611038v1
+2005-04-26,"Spin correlations in the reaction ""pi \vec D --> \vecΣΘ^+"" and the parity of Theta^+","We analyze two types of spin observables in the reaction $\pi \vec
+D\to\vec\Sigma\Theta^+$ near the threshold. One concerns the spin-transfer
+coefficients $K_x^x$ and $K_z^z$. The second one is the deuteron spin
+anisotropy. These observables are sensitive to the $\Theta^+$ parity and can be
+used as a tool for the $\Theta^+$ parity determination.",0504073v1
+1995-04-20,Dynamic Domain Walls in Strongly Driven Ferromagnets,"A multiple-time scaling analysis of the dissipative, transversely driven
+Landau-Lifshitz equation in presence of exchange, shape demagnetisation and
+week anisotropy fields is performed for a dynamic domain state. Stationary
+solutions of the resulting equations explain the spatiotemporal structure of
+the walls and are in agreement with previous simulations.",9504004v1
+1996-07-29,Numerical Simulation of Three-Dimensional Dendritic Growth,"Dendritic crystal growth in a pure undercooled melt is simulated
+quantitatively in three dimensions using a phase-field approach. The full
+non-axisymmetric morphology of the steady-state dendrite tip and $\sigma^*$ are
+determined as a function of anisotropy for a crystal with a cubic symmetry.
+Results are compared to experiment and used to critically test solvability
+theory.",9607005v1
+1997-09-25,Excitons with anisotropic effective mass,"We present a simple analytic scheme for calculating the binding energy of
+excitons in semiconductors that takes full account of the existing anisotropy
+in the effective mass, as a complement to the qualitative treatment in most
+textbooks. Results obtained for excitons in gallium nitride form the basis for
+a discussion of the accuracy of this approach.",9709036v1
+2001-01-07,Quantum Evolution Supergenerator of Superparamagnetic System in Discrete Orientation Model,"The supergenerator of superparamagnetic system quantum evolution is
+investigated in discrete orientation model (DOM). It is shown that the
+generator is J-self-adjoint one at the case of potential drift field agreed
+upon magnetic anisotropy of the sample investigated. Perturbation theory is
+used for spectral analysis. The qualitative dependence of resonance absorption
+spectrum on the relation between quantum and stochastic parameters is
+demonstrated.",0101043v1
+2001-04-19,The universal potential fluctuations,"It is assumed the existence of the universal potential fluctuations valid for
+all scales in the universe which follow the fractal law $\delta_U=(\Delta
+r/r)^2$. The value of the universal potential fluctuations is determined from
+the data on anisotropy of the cosmic microwave background on degree scales. It
+is suggested to test the existence of the universal potential fluctuations in
+the laboratory experiment.",0104057v1
+2002-09-12,Dipolar relaxation of cold sodium atoms in a magnetic field,"A quantum mechanical close coupling theory of spin relaxation in the
+stretched hyperfine level of sodium is presented. We calculate the dipolar
+relaxation rate of magnetically trapped cold sodium atoms in the magnetic
+field. The influence of shape resonances and the anisotropy of the dipolar
+interaction on the collision dynamics are explored. We examine the sensitivity
+of the calculated cross sections on the choice of asymptotic atomic state
+basis.",0209052v2
+2003-11-14,Two dimensional modulational instability in photorefractive media,"We study theoretically and experimentally the modulational instability of
+broad optical beams in photorefractive nonlinear media. We demonstrate the
+impact of the anisotropy of the nonlinearity on the growth rate of periodic
+perturbations. Our findings are confirmed by experimental measurements in a
+strontium barium niobate photorefractive crystal.",0311070v1
+2005-01-13,Terahertz pulse generation via optical rectification in photonic crystal microcavities,"Using a 3D fully-vectorial nonlinear time-domain analysis we numerically
+investigate the generation of terahertz radiation by pumping a photonic crystal
+microcavity out of resonance. High quality factors and a quadratic
+susceptibility lead to few-cycle terahertz pulses via optical rectification.
+Material dispersion as well as linear and nonlinear anisotropy is fully
+accounted for.",0501065v1
+2004-10-26,Lattice tube model of proteins,"We present a new lattice model for proteins that incorporates a tube-like
+anisotropy by introducing a preference for mutually parallel alignments in the
+conformations. The model is demonstrated to capture many aspects of real
+proteins.",0410031v1
+2005-05-10,Creation of Stable Multipartite Entangled States in Spin Chains with Defects,"We show how defects in a spin chain described by the XXZ model may be used to
+generate entangled states, such as Bell and W states, and how to maintain them
+with high fidelity. In the presence of several excitations, we also discuss how
+the anisotropy of the system may be combined with defects to effectively assist
+in the creation of the desired states.",0505072v1
+2007-04-09,Sensitivity of solar off-limb line profiles to electron density stratification and the velocity distribution anisotropy,"The effect of the electron density stratification on the intensity profiles
+of the H I Ly-$\alpha$ line and the O VI and Mg X doublets formed in solar
+coronal holes is investigated. We employ an analytical 2-D model of the large
+scale coronal magnetic field that provides a good representation of the corona
+at the minimum of solar activity. We use the mass-flux conservation equation to
+determine the outflow speed of the solar wind at any location in the solar
+corona and take into account the integration along the line of sight (LOS). The
+main assumption we make is that no anisotropy in the kinetic temperature of the
+coronal species is considered. We find that at distances greater than 1 Rsun
+from the solar surface the widths of the emitted lines of O VI and Mg X are
+sensitive to the details of the adopted electron density stratification.
+However, Ly-$\alpha$, which is a pure radiative line, is hardly affected. The
+calculated total intensities of Ly-$\alpha$ and the O VI doublet depend to a
+lesser degree on the density stratification and are comparable to the observed
+ones for most of the considered density models. The widths of the observed
+profiles of Ly-$\alpha$ and Mg X are well reproduced by most of the considered
+electron density stratifications, while for the O VI doublet only few
+stratifications give satisfying results. The densities deduced from SOHO data
+result in O VI profiles whose widths and intensity ratio are relatively close
+to the values observed by UVCS although only isotropic velocity distributions
+are employed. These density profiles also reproduce the other considered
+observables with good accuracy. Thus the need for a strong anisotropy of the
+velocity distribution (i.e. a temperature anisotropy) is not so clear cut as
+previous investigations of UVCS data suggested. ...",0704.1127v1
+2007-04-25,Anisotropic Locations of Satellite Galaxies: Clues to the Orientations of Galaxies within their Dark Matter Halos,"We investigate the locations of the satellites of relatively isolated host
+galaxies in the Sloan Digital Sky Survey and the Millennium Run simulation.
+Provided we use two distinct prescriptions to embed luminous galaxies within
+the simulated dark matter halos (ellipticals share the shapes of their halos,
+while disks have angular momenta that are aligned with the net angular momenta
+of their halos), we find a fair agreement between observation and theory.
+Averaged over scales r_p \le 500 kpc, the satellites of red, high-mass hosts
+with low star formation rates are found preferentially near the major axes of
+their hosts. In contrast, the satellites of blue, low-mass hosts with low star
+formation rates show little to no anisotropy when averaged over the same scale.
+The difference between the locations of the satellites of red and blue hosts
+cannot be explained by the effects of interlopers in the data. Instead, it is
+caused primarily by marked differences in the dependence of the mean satellite
+location, <\phi>, on the projected distance at which the satellites are found.
+We also find that the locations of red, high-mass satellites with low star
+formation rates show considerably more anisotropy than do the locations of
+blue, low--mass satellites with high star formation rates. There are two
+contributors to this result. First, the blue satellites have only recently
+arrived within their hosts' halos, while the red satellites arrived in the far
+distant past. Second, the sample of blue satellites is heavily contaminated by
+interlopers, which suppresses the measured anisotropy compared to the intrinsic
+anisotropy.",0704.3441v3
+2007-05-07,Can We Detect the Anisotropic Shapes of Quasar HII Regions During Reionization Through The Small-Scale Redshifted 21cm Power Spectrum?,"Light travel time delays distort the apparent shapes of HII regions
+surrounding bright quasars during early stages of cosmic reionization.
+Individual HII regions may remain undetectable in forthcoming redshifted 21 cm
+experiments. However, the systematic deformation along the line of sight may be
+detectable statistically, either by stacking tomographic 21cm images of quasars
+identified, for example, by JWST, or as small-scale anisotropy in the
+three-dimensional 21cm power spectrum. Here we consider the detectability of
+this effect. The anisotropy is largest when HII regions are large and expand
+rapidly, and we find that if bright quasars contributed to the early stages of
+reionization, then they can produce significant anisotropy, on scales
+comparable to the typical sizes of HII regions of the bright quasars (approx.
+30 Mpc and below). The effect therefore cannot be ignored when analyzing future
+21cm power spectra on small scales. If 10 percent of the volume of the IGM at
+redshift z=10 is ionized by quasars with typical ionizing luminosity of S= 5 x
+10^{56} photons/second, the distortions can enhance by more than 10 percent the
+21cm power spectrum in the radial (redshift) direction, relative to the
+transverse directions. The level of this anisotropy exceeds that due to
+redshift-space distortion, and has the opposite sign. We show that on-going
+experiments such as MWA should be able to detect this effect. A detection would
+reveal the presence of bright quasars, and shed light on the ionizing yield and
+age of the ionizing sources, and the distribution and small-scale clumping of
+neutral intergalactic gas in their vicinity.",0705.0981v2
+2007-05-25,Exact Activation Energy of Magnetic Single Domain Particles,"I present the exact analytical expression for the activation energy as a
+function of externally applied magnetic fields for a single--domain magnetic
+particle with uniaxial anisotropy (Stoner--Wohlfahrt model), and investigate
+the scaling behavior of the activation energy close to the switching boundary.",0705.3761v1
+2007-07-31,Functional relations from the Yang-Baxter algebra: Eigenvalues of the XXZ model with non-diagonal twisted and open boundary conditions,"In this work we consider a functional method in the theory of exactly
+solvable models based on the Yang-Baxter algebra. Using this method we derive
+the eigenvalues of the XXZ model with non-diagonal twisted and open boundary
+conditions for general values of the anisotropy and boundary parameters.",0708.0009v1
+2007-10-02,Reply to 'Difficulty in the Fermi-Liquid-Based Theory for the In-Plane Magnetic Anisotropy in Untwinned High-$T_c$ Superconductors',A Reply to the Comment by Hou-Jun Zhao and Jun Li,0710.0473v1
+2007-10-12,Probing the Origin of the Large-angle CMB Anomalies,"It has been argued that the large-angle cosmic microwave background
+anisotropy has anomalies at 3-sigma level. We review various proposed ideas to
+explain the origin of the anomalies and discuss how we can constrain the
+proposed models using future observational data.",0710.2404v1
+2007-10-23,Anisotropic Magnification Distortion of the 3D Galaxy Correlation: II. Fourier and Redshift Space,"In paper I of this series we discuss how magnification bias distorts the 3D
+correlation function by enhancing the observed correlation in the line-of-sight
+(LOS) orientation, especially on large scales. This lensing anisotropy is
+distinctive, making it possible to separately measure the galaxy-galaxy,
+galaxy-magnification {\it and} magnification-magnification correlations. Here
+we extend the discussion to the power spectrum and also to redshift space. In
+real space, pairs oriented close to the LOS direction are not protected against
+nonlinearity even if the pair separation is large; this is because nonlinear
+fluctuations can enter through gravitational lensing at a small transverse
+separation (or i.e. impact parameter). The situation in Fourier space is
+different: by focusing on a small wavenumber $k$, as is usually done, linearity
+is guaranteed because both the LOS and transverse wavenumbers must be small.
+This is why magnification distortion of the galaxy correlation appears less
+severe in Fourier space. Nonetheless, the effect is non-negligible, especially
+for the transverse Fourier modes, and should be taken into account in
+interpreting precision measurements of the galaxy power spectrum, for instance
+those that focus on the baryon oscillations. The lensing induced anisotropy of
+the power spectrum has a shape that is distinct from the more well known
+redshift space anisotropies due to peculiar motions and the Alcock-Paczynski
+effect. The lensing anisotropy is highly localized in Fourier space while
+redshift space distortions are more spread out. This means that one could
+separate the magnification bias component in real observations, implying that
+potentially it is possible to perform a gravitational lensing measurement
+without measuring galaxy shapes.",0710.4191v3
+2007-11-08,Super-horizon fluctuations and acoustic oscillations in relativistic heavy-ion collisions,"We focus on the initial state spatial anisotropies, originating at the
+thermalization stage, for central collisions in relativistic heavy-ion
+collisions. We propose that a plot of the root mean square values of the flow
+coefficients $\sqrt{\bar {v_n^2}} \equiv v_n^{rms}$, calculated in a lab fixed
+coordinate system, for a large range of $n$, from 1 to about 30, can give
+non-trivial information about the initial stages of the system and its
+evolution. We also argue that for all wavelengths $\lambda$ of the anisotropy
+(at the surface of the plasma region) much larger than the acoustic horizon
+size $H_s^{fr}$ at the freezeout stage, the resulting values of $v_n^{rms}$
+should be suppressed by a factor of order $2H_s^{fr}/\lambda$. With initial
+flow being zero, we discuss the possibility that the resulting flow could show
+imprints of coherent oscillations in the plot of $v_n^{rms}$ for sub-horizon
+modes. For gold-gold collision at 200 GeV, these features are expected to occur
+for n $\ge$ 5, with $n < 4$ modes showing supression. This has strong
+similarities with the physics of the anisotropies of the cosmic microwave
+background radiation (CMBR) resulting from inflationary density fluctuations in
+the universe. It seems possible that the statistical fluctuations due to finite
+multiplicity may not be able to mask such features in the flow data, or, at
+least a non-trivial overall shape of the plot of $v_n^{rms}$ may be inferred.
+In that case, the successes of analysis of CMBR anisotropy power spectrum to
+get cosmological parameters can be applied for relativistic heavy-ion
+collisions to learn about various relevant parameters at the early stages of
+the evolving system.",0711.1323v2
+2007-11-15,Fast magnetization in counterstreaming plasmas with temperature anisotropies,"Counterstreaming plasmas exhibits an electromagnetic unstable mode of
+filamentation type, which is responsible for the magnetization of plasma
+system. It is shown that filamentation instability becomes significantly faster
+when plasma is hotter in the streaming direction. This is relevant for
+astrophysical sources, where strong magnetic fields are expected to exist and
+explain the nothermal emission observed.",0711.2385v1
+2008-01-26,Diversity of critical behavior within a universality class,"We study spatial anisotropy effects on the bulk and finite-size critical
+behavior of the O$(n)$ symmetric anisotropic $\phi^4$ lattice model with
+periodic boundary conditions in a $d$-dimensional hypercubic geometry above, at
+and below $T_c$. The absence of two-scale factor universality is discussed for
+the bulk order-parameter correlation function, the bulk scattering intensity,
+and for several universal bulk amplitude relations. For the confined system,
+renormalization-group theory within the minimal subtraction scheme at fixed
+dimension $d$ for $2<d<4$ is employed. For the case of cubic symmetry and for
+$n=1$ our perturbation approach yields excellent agreement with the Monte Carlo
+(MC) data for the finite-size amplitude of the free energy of the
+three-dimensional Ising model at $T_c$ by Mon [Phys. Rev. Lett. {\bf 54}, 2671
+(1985)]. Below $T_c$ a minimum of the scaling function of the excess free
+energy is found. We predict a measurable dependence of this minimum on the
+anisotropy parameters. The relative anisotropy effect on the free energy is
+predicted to be significantly larger than that on the Binder cumulant. Our
+theory agrees quantitatively with the non-monotonic dependence of the Binder
+cumulant on the ferromagnetic next-nearest neighbor (NNN) coupling of the
+two-dimensional Ising model found by MC simulations of Selke and Shchur [J.
+Phys. {\bf A 38}, L739 (2005)]. Our theory also predicts a non-monotonic
+dependence for small values of the {\it antiferromagnetic} NNN coupling and the
+existence of a Lifschitz point at a larger value of this coupling. The
+nonuniversal anisotropy effects in the finite-size scaling regime are predicted
+to satisfy a kind of restricted universality. The tails of the large-$L$
+behavior at $T \neq T_c$ violate both finite-size scaling and universality.",0801.4096v2
+2008-02-15,The AUGER experiment - status and results,"The Auger experiment was designed to study the high-energy cosmic rays by
+measuring the properties of the showers produced in the atmosphere. The
+Southern Auger Observatory has taken data since January 2004. Results on mass
+composition, energy spectrum and anisotropy of the arrival directions are
+presented. The most important result is the recent observation of correlations
+with nearby extragalactic objects.",0802.2214v1
+2008-03-11,Entanglement and Berry Phase in Two Interacting Qubits,"Entanglement and Berry phase are investigated in two interacting qubit
+systems. The XXZ spin interaction model with a slowly rotating magnetic field
+is employed for the interaction between the two qubits. We show how the
+anisotropy of interaction reveals unique relations between the Berry phases and
+the entanglements for the eigenstates of the system.",0803.1524v1
+2008-06-09,The Doppler shift due to WMAP's spin mimics anisotropies in the cosmic microwave background,"This paper has been withdrawn because its ideas have been incorporated into
+arXiv:0905.3971 and explained much better there.",0806.1508v2
+2008-06-16,Thermal transport in the anisotropic Heisenberg chain with S = 1/2 and nearest-neighbor interactions,"The purpose of this note is to connect early work on thermal transport in
+spin-1/2 Heisenberg chains with uniaxial exchange anisotropy and
+nearest-neighbor interactions that was based on a moment analysis of the
+Fourier transform of the energy density correlation function with subsequent
+studies that make use of thermal current correlation functions.",0806.2670v1
+2008-07-29,Wormhole geometry from real feasible matter sources,"We provide a prescription of real feasible sources that supply fuel to
+construct a traversable wormhole. A class of exact solutions for
+Einstein-Maxwell field equations describing wormhole with an anisotropic matter
+distribution has been presented. The anisotropy plays a crucial role for the
+existence of the spacetime comprising wormhole geometry.",0807.4596v1
+2008-11-03,Imprints of microcausality violation on the cosmic microwave background,"We consider a modification of the Heisenberg algebra with the non-vanishing
+commutator of scalar field operators. We then identify the scalar field with
+the second quantized inflaton fluctuation and calculate effects of
+microcausality violation on the temperature anisotropy of cosmic microwave
+background radiation.",0811.0242v1
+2008-11-04,Anomalous scaling and anisotropy in models of passively advected vector fields,"The small and large scale problem of various passive vector models with
+anisotropic forcing is considered by solving exactly the equation for the pair
+correlation function. Emphasis is placed in the phenomena of anomalous scaling
+and the possible breakdown of isotropic dominance in the inertial range.",0811.0510v2
+2008-11-11,Simulating weak lensing on CMB maps,"We present a fast, arbitrarily accurate method to simulate the effect of
+gravitational lensing of the Cosmic Microwave Background anisotropies and
+polarization fields by large scale structures. We demonstrate the efficiency
+and accuracy of the method and exhibit their dependence on the algorithm
+parameters.",0811.1677v1
+2008-12-08,Equations of electromagnetism in some special anisotropic spaces,"We show that anisotropy of the space naturally leads to new terms in the
+expression of Lorentz force, as well as in the expressions of currents.",0812.1513v1
+2008-12-11,Lorentz Violation and Alpha-Decay,"Relating the effective Lorentz violation coefficients for composite particles
+to the coefficients for their constituent fields is a challenging problem. We
+calculate the Lorentz violation coefficients relevant to the dynamics of an
+alpha-particle in terms of proton and neutron coefficients. The alpha-particle
+coefficients would lead to anisotropies in the alpha-decays of nuclei, and
+because the decay process involves quantum tunneling, the effects of any
+Lorentz violations could be exponentially enhanced.",0812.2236v1
+2008-12-28,The variation of the electromagnetic coupling and quintessence,"The properties of quintessence are examined through the study of the
+variation of the electromagnetic coupling. We consider two simple quintessence
+models with a modified exponential potential and study the parameter space
+constraints derived from the existing observational bounds on the variation of
+the fine structure constant and the most recent Wilkinson Microwave Anisotropy
+Probe observations.",0812.4827v1
+2009-02-14,Electronic structure of BaCu$_2$As$_2$ and SrCu$_2$As$_2$: sp-band metals,"The electronic structures of ThCr$_2$Si$_2$ structure BaCu$_2$As$_2$ and
+SrCu$_2$As$_2$ are investigated using density functional calculations. The Cu
+$d$ orbitals are located at 3 eV and higher binding energy, and are therefore
+chemically inert with little contribution near the Fermi energy. These
+materials are moderate density of states, sp-band metals with large Fermi
+surfaces and low anisotropy.",0902.2502v1
+2009-03-25,Isotropic superconducting state and high critical currents in Fe1+yTe1-xSx single crystals,"We report single crystal growth and a study of superconducting properties in
+Fe_{1+y}Te_{1-x}S_{x}. We demonstrate the smallest upper critical field
+anisotropy, gamma=H_{c2}^{//c}/H_{c2}^{//a}, among all iron based
+superconductors, the value of gamma reaches 1.05 at T=0.65T_{C} for
+Fe_{1.09}Te_{0.89}S_{0.11}, while still maintaining large values of upper
+critical field.",0903.4430v2
+2009-03-30,Anisotropic Evolution Driven by Kinetic Term,"We present a simple model where anisotropic evolution is driven by kinetic
+term in extra dimensions. By introducing a canonical or a ghost kinetic term,
+the possibility of anisotropy is studied.",0903.5118v2
+2009-04-27,Constraints on the High-l Power Spectrum of Millimeter-wave Anisotropies from APEX-SZ,"We present measurements of the angular power spectrum of millimeter wave
+anisotropies with the APEX-SZ instrument. APEX-SZ has mapped 0.8 square degrees
+of sky at a frequency of 150 GHz with an angular resolution of 1'. These new
+measurements significantly improve the constraints on anisotropy power at 150
+GHz over the range of angular multipoles 3000 < l < 10,000, limiting the total
+astronomical signal in a flat band power to be less than 105 microK^2 at 95%
+CL. We expect both submillimeter-bright, dusty galaxies and to a lesser extent
+secondary CMB anisotropies from the Sunyaev-Zel'dovich effect (SZE) to
+significantly contribute to the observed power. Subtracting the SZE power
+spectrum expected for sigma_8=0.8 and masking bright sources, the best fit
+value for the remaining power is C_l = 1.1^{+0.9}_{-0.8} x 10^{-5} micro K^2
+(1.7^{+1.4}_{-1.3} Jy^2 sr^{-1}). This agrees well with model predictions for
+power due to submillimeter-bright, dusty galaxies. Comparing this power to the
+power detected by BLAST at 600 GHz, we find the frequency dependence of the
+source fluxes to be S_nu ~ nu^{2.6^{+0.4}_{-0.2}} if both experiments measure
+the same population of sources. Simultaneously fitting for the amplitude of the
+SZE power spectrum and a Poisson distributed point source population, we place
+an upper limit on the matter fluctuation amplitude of sigma_8 < 1.18 at 95%
+confidence.",0904.3939v2
+2009-04-28,"Density profile, velocity anisotropy and line-of-sight external convergence of SLACS gravitational lenses","Data from 58 strong-lensing events surveyed by the Sloan Lens ACS Survey are
+used to estimate the projected galaxy mass inside their Einstein radii by two
+independent methods: stellar dynamics and strong gravitational lensing. We
+perform a joint analysis of these two estimates inside models with up to three
+degrees of freedom with respect to the lens density profile, stellar velocity
+anisotropy, and line-of-sight (LOS) external convergence, which incorporates
+the effect of the large-scale structure on strong lensing. A Bayesian analysis
+is employed to estimate the model parameters, evaluate their significance and
+compare models. We find that the data favor Jaffe's light profile over
+Hernquist's, but that any particular choice between these two does not change
+the qualitative conclusions with respect to the features of the system that we
+investigate. The density profile is compatible with an isothermal, being
+sightly steeper and having an uncertainty in the logarithmic slope of the order
+of 5% in models that take into account a prior ignorance on anisotropy and
+external convergence. We identify a considerable degeneracy between the density
+profile slope and the anisotropy parameter, which largely increases the
+uncertainties in the estimates of these parameters, but we encounter no
+evidence in favor of an anisotropic velocity distribution on average for the
+whole sample. An LOS external convergence following a prior probability
+distribution given by cosmology has a small effect on the estimation of the
+lens density profile, but can increase the dispersion of its value by nearly
+40%.",0904.4381v4
+2009-06-02,Patterned and Disordered Continuous Abelian Sandpile Model,"We study critical properties of the continuous Abelian sandpile model with
+anisotropies in toppling rules that produce ordered patterns on it. Also we
+consider the continuous directed sandpile model perturbed by a weak quenched
+randomness and study critical behavior of the model using perturbative
+conformal field theory and show the model has a new random fixed point.",0906.0459v1
+2009-08-10,Tunnel magnetoresistance of magnetic junctions with cubic symmetry of the layers,"A tunnel magnetic junction is considered with magnetic hard and magnetic soft
+layers of cubic symmetry. The magnetic switching is analyzed of the layers by a
+magnetic field perpendicular to the initial magnetizations. In such a
+situation, an additional peak of the TMR ratio appears at the magnetic field
+value lower substantially than the anisotropy energy of the soft layer.",0908.1278v1
+2009-09-09,Non-Gaussianity in WMAP Data Due to the Correlation of CMB Lensing Potential with Secondary Anisotropies,"We measure the skewness power spectrum of the Cosmic Microwave Background
+(CMB) anisotropies optimized for a detection of the secondary bispectrum
+generated by the correlation of the CMB lensing potential with integrated
+Sachs-Wolfe effect and the Sunyaev-Zel'dovich effect. The covariance of our
+measurements is generated by Monte-Carlo simulations of Gaussian CMB fields
+with noise properties consistent with Wilkinson Microwave Anisotropy Probe
+(WMAP) 5-year data. When interpreting multi-frequency measurements we also take
+into account the confusion resulting from unresolved radio point sources. We
+analyze Q, V and W-band WMAP 5-year raw and foreground-cleaned maps using the
+KQ75 mask out to l_max=600. We find no significant evidence for a non-zero
+non-Gaussian signal from the lensing-secondary correlation in all three bands
+and we constrain the overall amplitude of the cross power spectrum between CMB
+lensing potential and the sum of SZ and ISW fluctuations to be 0.42 \pm 0.86
+and 1.19 \pm 0.86 in combined V and W-band raw and foreground-cleaned maps
+provided by the WMAP team, respectively. The point source amplitude at the
+bispectrum level measured with this skewness power spectrum is higher than
+previous measurements of point source non-Gaussianity. We also consider an
+analysis where we also account for the primordial non-Gaussianity in addition
+to lensing-secondary bispectrum and point sources. The focus of this paper is
+on secondary anisotropies. Consequently the estimator is not optimised for
+primordial non-Gaussianity and the limit we find on local non-Gaussianity from
+the foreground-cleaned V+W maps is f_NL = -13 \pm 62, when marginalized over
+point sources and lensing-ISW/SZ constributions to the total bispectrum.",0909.1837v1
+2009-09-15,The transport coefficient $\hat{q}$ in an anisotropic plasma,"We investigate the jet quenching parameter in the case of a fast moving quark
+in an anisotropic plasma. In the leading log approximation, strong indications
+are found that the transport coefficient increases with increasing anisotropy.
+Implications for the phenomenology at RHIC are discussed.",0909.2794v1
+2009-09-16,Matrix Product States and Quantum Phase Transitions,"We have developed a new approach based on matrix product representations of
+ground states to study Quantum Phase Transitions (QPT). As confirmation of the
+power of our approach we have analytically analyzed the XXZ spin-one chain with
+uniaxial single-ion-type anisotropy and our results compare favourably with
+previous numerical studies. In addition, our description lets to know which
+part of parameters space of the Hamiltonian is most likely to be exactly
+solvable.",0909.2928v1
+2009-10-16,Constraints on f_nl and g_nl from the analysis of the N-pdf of the CMB large scale anisotropies,"[Abridged] In this paper we explore a local non-linear perturbative model up
+to third order as a general characterization of the CMB anisotropies. We focus
+our analysis in large scale anisotropies. At these angular scales, the
+non-Gaussian description proposed in this work defaults (under certain
+conditions) to an approximated local form of the weak non-linear coupling
+inflationary model. In particular, quadratic and cubic terms are governed by
+the non-linear coupling parameters f_nl and g_nl, respectively. The extension
+proposed in this paper allows us to directly constrain these non-linear
+parameters. Applying the proposed methodology to WMAP 5-yr data, we obtain -5.6
+x 10^5 < g_nl < 6.4 x 10^5, at 95% CL. This result is in agreement with
+previous findings obtained for equivalent non-Gaussian models and with
+different non-Gaussian estimators. A model selection test is performed,
+indicating that a Gaussian model is preferred to the non-Gaussian scenario.
+When comparing different non-Gaussian models, we observe that a pure f_nl model
+is the most favoured case, and that a pure g_nl model is more likely than a
+general non-Gaussian scenario. Finally, we have analyzed the WMAP data in two
+independent hemispheres, in particular the ones defined by the dipolar pattern
+found by Hoftuft et al. 2009. We show that, whereas g_nl is still compatible
+with zero for both hemispheres, it is not the case for f_nl (with a p-value
+0.04). However, if anisotropy of the data is assumed, the distance between the
+likelihood distributions for each hemisphere is larger than expected from
+Gaussian and anisotropic simulations, also for g_nl (with a p-value of 0.001 in
+the case of this parameter). This result is an extra evidence for the CMB
+asymmetries previously reported in WMAP data.",0910.3196v2
+2009-12-08,Magnetofluid dynamics of magnetized cosmic plasma: firehose and gyrothermal instabilities,"Both global dynamics and turbulence in magnetized weakly collisional cosmic
+plasmas are described by general magnetofluid equations that contain pressure
+anisotropies and heat fluxes that must be calculated from microscopic plasma
+kinetic theory. It is shown that even without a detailed calculation of the
+pressure anisotropy or the heat fluxes, one finds the macroscale dynamics to be
+generically unstable to microscale Alfvenically polarized fluctuations. Two
+instabilities are considered in detail: the parallel firehose instability
+(including the finite-Larmor-radius effects that determine the fastest growing
+mode) and the gyrothermal instability (GTI). The latter is a new result - it is
+shown that a parallel ion heat flux destabilizes Alfvenically polarized
+fluctuations even in the absence of the negative pressure anisotropy required
+for the firehose. The main conclusion is that both pressure anisotropies and
+heat fluxes trigger plasma microinstabilities and, therefore, their values will
+likely be set by the nonlinear evolution of these instabilities. Ideas for
+understanding this nonlinear evolution are discussed. It is argued that cosmic
+plasmas will generically be ""three-scale systems,"" comprising global dynamics,
+mesoscale turbulence and microscale plasma fluctuations. The astrophysical
+example of cool cores of galaxy clusters is considered and it is noted that
+observations point to turbulence in clusters being in a marginal state with
+respect to plasma microinstabilities and so it is the plasma microphysics that
+is likely to set the heating and conduction properties of the intracluster
+medium. In particular, a lower bound on the scale of temperature fluctuations
+implied by the GTI is derived.",0912.1359v2
+2009-12-08,A dipole anisotropy of galaxy distribution: Does the CMB rest-frame exist in the local universe?,"The peculiar motion of the Earth causes a dipole anisotropy modulation in the
+distant galaxy distribution due to the aberration effect. However, the
+amplitude and angular direction of the effect is not necessarily the same as
+those of the cosmic microwave background (CMB) dipole anisotropy due to the
+growth of cosmic structures. In other words exploring the aberration effect may
+give us a clue to the horizon-scale physics perhaps related to the cosmic
+acceleration. In this paper we develop a method to explore the dipole angular
+modulation from the pixelized galaxy data on the sky properly taking into
+account the covariances due to the shot noise and the intrinsic galaxy
+clustering contamination as well as the partial sky coverage. We applied the
+method to the galaxy catalogs constructed from the Sloan Digital Sky Survey
+(SDSS) Data Release 6 data. After constructing the four galaxy catalogs that
+are different in the ranges of magnitudes and photometric redshifts to study
+possible systematics, we found that the most robust sample against systematics
+indicates no dipole anisotropy in the galaxy distribution. This finding is
+consistent with the expectation from the concordance Lambda-dominated cold dark
+matter model. Finally we argue that an almost full-sky galaxy survey such as
+LSST may allow for a significant detection of the aberration effect of the CMB
+dipole having the precision of constraining the angular direction to ~ 20
+degrees in radius. Assuming a hypothetical LSST galaxy survey, we find that
+this method can confirm or reject the result implied from a stacked analysis of
+the kinetic Sunyaev-Zel'dovich effect of X-ray luminous clusters in Kashlinsky
+et al. (2008,2009) if the implied cosmic bulk flow is not extended out to the
+horizon.",0912.1460v2
+2010-01-18,Nearest-neighbor coupling asymmetry in the generation of cluster states,"We demonstrate that charge-qubit cluster state generation by capacitive
+coupling is anisotropic. Specifically, horizontal vs vertical nearest-neighbor
+inter-qubit coupling differs in a rectangular lattice. We show how to
+ameliorate this anisotropy by applying potential biases to the array of double
+dots.",1001.2877v2
+2010-04-22,Collisionless reconnection: Mechanism of self-ignition in thin current sheets,"The spontaneous onset of magnetic reconnection in thin collisionless current
+sheets is shown to result from a thermal-anisotropy driven magnetic
+Weibel-mode, generating seed-magnetic field {\sf X}-points in the centre of the
+current layer.",1004.3992v1
+2010-06-29,Magnetostatics of synthetic ferrimagnet elements,"We calculate the magnetostatic energy of synthetic ferrimagnet (SyF)
+elements, consisting of two thin ferromagnetic layers coupled
+antiferromagnetically through RKKY coupling. We calculate exact formulas as
+well as approximate yet accurate ones, which can be used to easily derive
+energy barriers and anisotropy fields of SyF. These can be used to evaluate
+coercivity, thermal stability and other useful quantities.",1006.5531v2
+2010-09-01,Entanglement in a Time-Dependent Coupled XY Spin Chain in an External Magnetic Field,"We consider an infinite one dimensional anisotropic XY spin chain with a
+nearest neighbor time-dependent Heisenberg coupling J(t) between the spins in
+presence of a time-dependent magnetic field h(t). We discuss a general solution
+for the system and present an exact solution for particular choice of J and h
+of practical interest. We investigate the dynamics of entanglement for
+different degrees of anisotropy of the system and at both zero and finite
+temperatures. We find that the time evolution of entanglement in the system
+show non-ergodic and critical behavior at zero and finite temperatures and
+different degrees of anisotropy. The asymptotic behavior of entanglement at the
+infinite time limit at zero temperature and constant J and h depends only the
+parameter lambda=J/h rather than the individual values of J and h for all
+degrees of anisotropy but changes for nonzero temperature. Furthermore, the
+asymptotic behavior is very sensitive to the initial values of J and h and for
+particular choices we may create finite asymptotic entanglement regardless of
+the final values of J and h. The persistence of quantum effects in the system
+as it evolves and as the temperature is raised is studied by monitoring the
+entanglement. We find that the quantum effects dominates within certain regions
+of the kT-lambda space that vary significantly depending on the degree of the
+anisotropy of the system. Particularly, the quantum effects in the Ising model
+case persists in the vicinity of both its critical phase transition point and
+zero temperature as it evolves in time. Moreover, the interplay between the
+different system parameters to tune and control the entanglement evolution is
+explored.",1009.0648v3
+2010-10-01,Implications of the Cosmic Ray Electron Spectrum and Anisotropy measured with Fermi-LAT,"The Fermi Large Area Telescope (LAT) collaboration recently released the
+updated results of the measurement of the cosmic ray electron (CRE) spectrum
+and published its first constraints on the CRE anisotropy. With respect to the
+previous Fermi-LAT results, the CRE spectrum measurement was extended down from
+20 to 7 GeV, thus providing a better lever arm to discriminate theoretical
+models. Here we show that the new data strengthen the evidence for the presence
+of two distinct electron and positron spectral components. Furthermore, we show
+that under such hypothesis most relevant CRE and positron data sets are
+remarkably well reproduced. Consistent fits of cosmic-ray nuclei and antiproton
+data, which are crucial to validate the adopted propagation setup(s) and to fix
+the solar modulation potential, are obtained for the Kraichnan and
+plain-diffusion propagation setups, while the Kolmogorov one is disfavored. We
+then confirm that nearby pulsars are viable source candidates of the required
+$e^\pm$ extra-component. In that case, we show that the predicted CRE
+anisotropy is compatible with Fermi-LAT constraints and that a positive
+detection should be at hand of that observatory. Models assuming that only
+nearby supernova remnants contribute to the high energy tail of the observed
+CRE spectrum are in contrast with anisotropy limits.",1010.0174v2
+2010-10-19,Anisotropic Function Spaces and Elliptic Boundary Value Problems,"In this paper, we study anisotropic Bessel potential and Besov spaces, where
+the anisotropy measures the extra amount of regularity in certain directions.
+Some basic properties of these spaces are established along with applications
+to elliptic boundary value problems.",1010.4046v2
+2010-10-30,Symmetry breaking orbital anisotropy on detwinned Ba(Fe1-xCox)2As2 above the spin density wave transition,"Nematicity, defined as broken rotational symmetry, has recently been observed
+in competing phases proximate to the superconducting phase in the cuprate high
+temperature superconductors. Similarly, the new iron-based high temperature
+superconductors exhibit a tetragonal to orthorhombic structural transition
+(i.e. a broken C4 symmetry) that either precedes or is coincident with a
+collinear spin density wave (SDW) transition in undoped parent compounds, and
+superconductivity arises when both transitions are suppressed via doping.
+Evidence for strong in-plane anisotropy in the SDW state in this family of
+compounds has been reported by neutron scattering, scanning tunneling
+microscopy, and transport measurements. Here we present an angle resolved
+photoemission spectroscopy study of detwinned single crystals of a
+representative family of electron-doped iron-arsenide superconductors,
+Ba(Fe1-xCox)2As2 in the underdoped region. The crystals were detwinned via
+application of in-plane uniaxial stress, enabling measurements of single domain
+electronic structure in the orthorhombic state. At low temperatures, our
+results clearly demonstrate an in-plane electronic anisotropy characterized by
+a large energy splitting of two orthogonal bands with dominant dxz and dyz
+character, which is consistent with anisotropy observed by other probes. For
+compositions x>0, for which the structural transition (TS) precedes the
+magnetic transition (TSDW), an anisotropic splitting is observed to develop
+above TSDW, indicating that it is specifically associated with TS. For
+unstressed crystals, the band splitting is observed close to TS, whereas for
+stressed crystals the splitting is observed to considerably higher
+temperatures, revealing the presence of a surprisingly large in-plane nematic
+susceptibility in the electronic structure.",1011.0050v2
+2010-11-22,Electrodynamic Response of the Charge Ordering Phase: Dielectric and Optical Studies of alpha-(BEDT-TTF)2I3,"We report on the anisotropic response, the charge and lattice dynamics of
+normal and charge-ordered phases with horizontal stripes in single crystals of
+the organic conductor alpha-(BEDT-TTF)2I3 determined by dc resistivity,
+dielectric and optical spectroscopy. An overdamped Drude response and a small
+conductivity anisotropy observed in optics is consistent with a weakly
+temperature dependent dc conductivity and anisotropy at high temperatures. The
+splitting of the molecular vibrations nu27(Bu) evidences the abrupt onset of
+static charge order below TCO=136 K. The drop of optical conductivity measured
+within the ab plane of the crystal is characterized by an isotropic gap that
+opens of approximately 75 meV with several phonons becoming pronounced below.
+Conversely, the dc conductivity anisotropy rises steeply, attaining at 50 K a
+value 25 times larger than at high temperatures. The dielectric response within
+this plane reveals two broad relaxation modes of strength Deltaepsilon_LD ~=
+5000 and Deltaepsilon_SD ~= 400, centered at 1 kHz < f_LD < 100 MHz and f_SD ~=
+1 MHz. The anisotropy of the large-mode (LD) mean relaxation time closely
+follows the temperature behavior of the respective dc conductivity ratio. We
+argue that this phason-like excitation is best described as a long-wavelength
+excitation of a 2kF bond-charge density wave expected theoretically for layered
+quarter-filled electronic systems with horizontal stripes. Conversely, based on
+the theoretically expected ferroelectric-like nature of the charge-ordered
+phase, we associate the small-mode (SD) relaxation with the motion of
+domain-wall pairs, created at the interface between two types of domains, along
+the a and b axes. We also consider other possible theoretical interpretations
+and discuss their limitations.",1011.4912v2
+2011-01-01,Gravimagnetic shock waves in the anisotropic plasma,"The relativistic magnetohydrodynamic equations for the anisotropic
+magnetoactive plasma are obtained and accurately integrated in the plane
+gravitational wave metrics. The dependence of the induction mechanism of the
+gravimagnetic shock waves on the degree of the magnetoactive plasma anisotropy
+is analyzed.",1101.0374v1
+2011-04-05,Explicit constructions of operator scaling Gaussian fields,"We propose an explicit way to generate a large class of Operator scaling
+Gaussian random fields (OSGRF). Such fields are anisotropic generalizations of
+selfsimilar fields. More specifically, we are able to construct any Gaussian
+field belonging to this class with given Hurst index and exponent. Our
+construction provides - for simulations of texture as well as for detection of
+anisotropies in an image - a large class of models with controlled anisotropic
+geometries and structures.",1104.0774v1
+2011-06-08,On a proof of the collapse conjecture for a diagonal Bianchi type-IX vacuum space-time,"It is given a simple proof of the collapse conjecture for a diagonal Bianchi
+type-IX vacuum space-time. It is shown that the codimension of the infinity
+stable attractor, restricted to the anisotropy plane, is not zero, thus proving
+that ""escape along a channel"" is impossible.",1106.1534v1
+2011-06-15,Role of d-wave pairing in $A15$ superconductors,"We argue that the recent Raman spectroscopy observation of a sharp mode in
+s-wave superconducting V$_3$Si is due to a competing d-wave pairing state. We
+present microscopic arguments for the origin of this d-wave order. We further
+argue that the d-wave order explains the observed shrinking of the vortex core
+structure at anomalously low magnetic fields and the large anisotropy observed
+in the upper critical field.",1106.2931v1
+2011-06-29,STAR Highlights,"We report selected results from STAR collaboration at RHIC, focusing on
+jet-hadron and jet-like correlations, quarkonium suppression and collectivity,
+di-electron spectrum in both p+p and Au+Au, and higher moments of net-protons
+as well as azimuthal anisotropy from RHIC Beam Energy Scan program.",1106.6021v1
+2011-07-15,Studying the stochasticity in astrophysical signals,"The efficiency of the Kolmogorov-Arnold technique for the astrophysical
+signals is studied modeling sequences with both random and regular properties.
+This technique has been applied to the study of the structures in cosmic
+microwave background maps obtained by the Wilkinson Microwave Anisotropy Probe.",1107.3091v1
+2011-08-02,Cosmic ray acceleration at oblique shocks,"We show that the diffusion approximation breaks down for particle
+acceleration at oblique shocks with velocities typical of young supernova
+remnants. Higher order anisotropies flatten the spectral index at
+quasi-parallel shocks and steepen the spectral index at quasi-perpendicular
+shocks. We compare the theory with observed spectral indices.",1108.0582v1
+2011-09-07,Planar approximation for spin transfer systems with application to tilted polarizer devices,"Planar spin-transfer devices with dominating easy-plane anisotropy can be
+described by an effective one-dimensional equation for the in-plane angle. Such
+a description provides an intuitive qualitative understanding of the magnetic
+dynamics. We give a detailed derivation of the effective planar equation and
+use it to describe magnetic switching in devices with tilted polarizer.",1109.1331v1
+2011-09-07,Planar approximation for the frequencies of spin transfer oscillators,"A large class of spin transfer oscillators use the free layer with a strong
+easy plane anisotropy, which forces its magnetization to move close to the
+plane. We show that in this situation the effective planar approximation
+provides a fast and accurate way of calculating the oscillator frequency.",1109.1335v1
+2011-10-10,Vortex structures of a two-component BEC for large anisotropies,"We calculate the vortex structures of an elongated two-component
+Bose-Einstein condensate. We study how these structures depend on the
+intra-component and inter-component interaction strengths. We present analytic
+and numeric results respectively at weak and strong interactions; finding
+lattices with different interlocking geometries: triangular, square,
+rectangular and double-core.",1110.2135v1
+2011-11-11,The IceCube Neutrino Observatory III: Cosmic Rays,"Cosmic rays and related measurements: IceTop overview; IceTop calibration;
+Cosmic ray composition; Air shower measurements; Studies of cosmic ray muons;
+Studies of PeV gamma rays; Cosmic ray anisotropy; Forbush decrease; Submitted
+papers to the 32nd International Cosmic Ray Conference, Beijing 2011.",1111.2735v2
+2011-12-07,Sixteen-state magnetic memory based on the extraordinary Hall effect,"We report on a proof-of-concept study of split-cell magnetic storage in which
+multi-bit magnetic memory cells are composed of several multilevel
+ferromagnetic dots with perpendicular magnetic anisotropy. Extraordinary Hall
+effect is used for reading the data. Feasibility of the approach is supported
+by realization of four-, eight- and sixteen- state cells.",1112.1624v1
+2011-12-29,Apart Cen A are UHECR mostly heavy radioactive and galactic nuclei?,"Earliest AUGER UHECR anisotropy correlated with AGN within a GZK Universe
+almost fade away. Recent UHECR mass compositions did show a negligible nucleon
+composition and an UHECR nuclei (light or heavy) signature. The absence of
+UHECR events toward the Virgo cluster, an unique spread clustering of events
+around Cen-A, our nearest AGN, suggested a He-like nuclei as the main
+extragalactic UHECR component from Cen A, coexisting with Auger and HIRES
+composition. Because the light nuclei fragility such He UHECR cannot arrive
+from Virgo. Multiplet at twenty EeV along Cen A recently discovered by Auger
+confirm this interpretation to be indebt to fragments (D;He3; p) that had to
+reach us along the same UHECR. Remaining majority of UHECR clustering are
+partially correlated with a gamma noise at (1-3 MeV) in Comptel sky, linked to
+Al 26 galactic radioactive map as well as to a few TeV gamma anisotropy maps;
+rare UHECR triplet are overlapping on Vela TeV anisotropy. Therefore UHECR
+might be also (or mostly) heavy radioactive galactic nuclei as Ni55, Ni56, Ni57
+and Co57 bent from the sources whose gamma and beta radioactivity and decay in
+flight is boosted (by Lorentz factor near a billion), leading to TeV correlated
+sky anisotropy. Galactic UHECR signals inside the inner center maybe suppressed
+by Lorentz bending forces. More clustering around external galactic plane is
+expected. Magellanic Cloud and Magellanic Stream may also rise in UHECR maps
+(as well as in multiplet). Future UHECR clustering might be observed around Cas
+A and Cygnus by T.A. The UHECR spectra cut off may be just the imprint of a
+galactic confinement and-or a spectroscopic heavy composition decrease step.",1112.6388v2
+2012-01-16,Particles Flux of Ultrahigh Energy from a Galactic Plane,"Arrival directions of particles were analyzed according to the arrays of
+extensive air showers (EAS) data. A new method of sources search and anisotropy
+of arrival directions particles is suggested. There was found the particles
+flux of ultrahigh energy from the galactic plane that exceeds the expected
+number of particles in the case of isotropy more than 4\sigma and 5\sigma.",1201.3143v1
+2012-01-31,On the absorption of microwaves by the one-dimensional spin-1/2 Heisenberg-Ising magnet,"We analyze the absorption of microwaves by the Heisenberg-Ising chain
+combining exact calculations, based on the integrability of the model, with
+numerical calculations. Within linear response theory the absorbed intensity is
+determined by the imaginary part of the dynamical susceptibility. The moments
+of the normalized intensity can be used to define the shift of the resonance
+frequency induced by the interactions and the line width independently of the
+shape of the spectral line. These moments can be calculated exactly as
+functions of temperature and strength of an external magnetic field, as long as
+the field is directed along the symmetry axis of the chain. This allows us to
+discuss the line width and the resonance shift for a given magnetic field in
+the full range of possible anisotropy parameters. For the interpretation of
+these data we need a qualitative knowledge of the line shape which we obtain
+from fully numerical calculations for finite chains. Exact analytical results
+on the line shape are out of reach of current theories. From our numerical work
+we could extract, however, an empirical parameter-free model of the line shape
+at high temperatures which is extremely accurate over a wide range of
+anisotropy parameters and is exact at the free fermion point and at the
+isotropic point. Another prediction of the line shape can be made in the
+zero-temperature and zero magnetic field limit, where the sufficiently
+anisotropic model shows strong absorption. For anisotropy parameters in the
+massive phase we derive the exact two-spinon contribution to the spectral line.
+From the intensity sum rule it can be estimated that this contribution accounts
+for more than 80% of the spectral weight if the anisotropy parameter is
+moderately above its value at the isotropic point.",1201.6523v1
+2012-03-09,Material Laws and Numerical Methods in Applied Superconductivity,"Contents Preface I Electromagnetism of type II superconductors 1 General
+Statements Of The Critical State 1.1 The CS In The Maxwell Equations Formalism
+1.2 The CS Regime And The MQS Limit 2 Variational Theory for CS Problems 2.1
+General Principles Of The Variational Method 2.2 The Material Law: SCs with
+magnetic anisotropy 2.2.1 Onto the 1D Critical States 2.2.2 Towards The 3D
+Critical States 3 Computational Method Conclusions I References I II Critical
+State Problems:Effects & Applications 4 Type-II SCs With Intrinsic Magnetic
+Anisotropy 4.1 3D variational statement in slab geometry 4.2 Isotropic
+predictions in -3D- configurations 4.3 T-states in -3D- configurations 4.4
+CT-states in -3D- configurations 4.5 Smooth critical states in -3D-
+configurations Appendix I Critical angle gradient in -3D- configurations 5 The
+Longitudinal Transport Problem 5.1 Simplified analytical models and beyond
+5.1.1 The simplest analytical model 5.1.2 The SDCST statement and the BM's
+approach 5.2 Magnetic anisotropy and the uncommon effects 5.2.1 Extremal case:
+The T-states model 5.2.2 Material laws with magnetic anisotropy: CT\chi -
+models 6 Electromagnetism For Superconducting Wires 6.1 Theoretical framework
+and general considerations 6.2 SC wires subjected to isolated external sources
+6.2.1 Wires with an injected AC transport current 6.2.2 Wires under an external
+AC magnetic flux 6.2.3 Ultimate considerations on the AC losses 6.3 SC wires
+under simultaneous AC excitations (B_{0},I_{tr}) 6.3.1 Synchronous excitations
+6.3.2 Asynchronous excitations Conclusions II References II Supplementary
+Material II III Microscopical aspects also analyzed 7 E-Ph Theory And The Nodal
+Kink Effect In HTSC 8 Is it necessary to go beyond the E-Ph mode? Conclusions
+III References III Supplementary Material III IV Addenda",1203.2159v1
+2012-03-14,Measurement of the azimuthal anisotropy for charged particle production in sqrt(s_NN) = 2.76 TeV lead-lead collisions with the ATLAS detector,"Differential measurements of charged particle azimuthal anisotropy are
+presented for lead-lead collisions at sqrt(s_NN) = 2.76 TeV with the ATLAS
+detector at the LHC, based on an integrated luminosity of approximately 8
+mb^-1. This anisotropy is characterized via a Fourier expansion of the
+distribution of charged particles in azimuthal angle (phi), with the
+coefficients v_n denoting the magnitude of the anisotropy. Significant v_2-v_6
+values are obtained as a function of transverse momentum (0.5<pT<20 GeV),
+pseudorapidity (|eta|<2.5) and centrality using an event plane method. The v_n
+values for n>=3 are found to vary weakly with both eta and centrality, and
+their pT dependencies are found to follow an approximate scaling relation,
+v_n^{1/n}(pT) \propto v_2^{1/2}(pT). A Fourier analysis of the charged particle
+pair distribution in relative azimuthal angle (Dphi=phi_a-phi_b) is performed
+to extract the coefficients v_{n,n}=<cos (n Dphi)>. For pairs of charged
+particles with a large pseudorapidity gap (|Deta=eta_a-eta_b|>2) and one
+particle with pT<3 GeV, the v_{2,2}-v_{6,6} values are found to factorize as
+v_{n,n}(pT^a,pT^b) ~ v_n(pT^a)v_n(pT^b) in central and mid-central events. Such
+factorization suggests that these values of v_{2,2}-v_{6,6} are primarily due
+to the response of the created matter to the fluctuations in the geometry of
+the initial state. A detailed study shows that the v_{1,1}(pT^a,pT^b) data are
+consistent with the combined contributions from a rapidity-even v_1 and global
+momentum conservation. A two-component fit is used to extract the v_1
+contribution. The extracted v_1 is observed to cross zero at pT\sim1.0 GeV,
+reaches a maximum at 4-5 GeV with a value comparable to that for v_3, and
+decreases at higher pT.",1203.3087v3
+2012-04-20,Interplay between Kondo tunneling and Rashba precession,"The influence of Thomas - Rashba precession on the physics of Kondo tunneling
+through quantum dots is analyzed. It is shown that this precession is relevant
+only at finite magnetic fields. Thomas - Rashba precession results in peculiar
+anisotropy of the effective g-factor and initiates dephasing of the Kondo
+tunneling amplitude at low temperature, that is strongly dependent on the
+magnetic field.",1204.4695v1
+2012-06-06,A Conditional Luminosity Function Model of the Cosmic Far-Infrared Background Anisotropy Power Spectrum,"The cosmic far-infrared background (CFIRB) is expected to be generated by
+faint, dusty star-forming galaxies during the peak epoch of galaxy formation.
+The anisotropy power spectrum of the CFIRB captures the spatial distribution of
+these galaxies in dark matter halos and the spatial distribution of dark matter
+halos in the large-scale structure. Existing halo models of CFIRB anisotropy
+power spectrum are either incomplete or lead to halo model parameters that are
+inconsistent with the galaxy distribution selected at other wavelengths. Here
+we present a conditional luminosity function approach to describe the far-IR
+bright galaxies. We model the 250 um luminosity function and its evolution with
+redshift and model-fit the CFIRB power spectrum at 250 um measured by the
+Herschel Space Observatory. We introduce a redshift dependent duty-cycle
+parameter so that we are able to estimate the typical duration of the dusty
+star formation process in the dark matter halos as a function of redshifts. We
+find the duty cycle of galaxies contributing to the far-IR background is 0.3 to
+0.5 with a dusty star-formation phase lasting for \sim0.3-1.6 Gyrs. This result
+confirms the general expectation that the far-IR background is dominated by
+star-forming galaxies in an extended phases, not bright starbursts that are
+driven by galaxy mergers and last \sim10-100 Myrs. The halo occupation number
+for satellite galaxies has a power-law slope that is close to unity over 0<z<4.
+We find that the minimum halo mass for dusty, star-forming galaxies with
+L_250>10^{10} L_Sun is 2\times10^{11}M_Sun and 3\times 10^{10}M_Sun at z=1 and
+2, respectively. Integrating over the galaxy population with L_250>10^{9}
+L_Sun, we find that the cosmic density of dust residing in the dusty,
+star-forming galaxies responsible for the background anisotropies
+\Omega_{dust}\sim3\times10^{-6} to 2\times10^{-5}.",1206.1324v2
+2012-06-19,Constraints on the shapes of galaxy dark matter haloes from weak gravitational lensing,"We study the shapes of galaxy dark matter haloes by measuring the anisotropy
+of the weak gravitational lensing signal around galaxies in the second
+Red-sequence Cluster Survey (RCS2). We determine the average shear anisotropy
+within the virial radius for three lens samples: all galaxies with
+19<m_r'<21.5, and the `red' and `blue' samples, whose lensing signals are
+dominated by massive low-redshift early-type and late-type galaxies,
+respectively. To study the environmental dependence of the lensing signal, we
+separate each lens sample into an isolated and clustered part and analyse them
+separately. We also measure the azimuthal dependence of the distribution of
+physically associated galaxies around the lens samples. We find that these
+satellites preferentially reside near the major axis of the lenses, and
+constrain the angle between the major axis of the lens and the average location
+of the satellites to <theta>=43.7 deg +/- 0.3 deg for the `all' lenses,
+<theta>=41.7 deg +/- 0.5 deg for the `red' lenses and <theta>=42.0 deg +/- 1.4
+deg for the `blue' lenses. For the `all' sample, we find that the anisotropy of
+the galaxy-mass cross-correlation function <f-f_45>=0.23 +/- 0.12, providing
+weak support for the view that the average galaxy is embedded in, and
+preferentially aligned with, a triaxial dark matter halo. Assuming an
+elliptical Navarro-Frenk-White (NFW) profile, we find that the ratio of the
+dark matter halo ellipticity and the galaxy ellipticity
+f_h=e_h/e_g=1.50+1.03-1.01, which for a mean lens ellipticity of 0.25
+corresponds to a projected halo ellipticity of e_h=0.38+0.26-0.25 if the halo
+and the lens are perfectly aligned. For isolated galaxies of the `all' sample,
+the average shear anisotropy increases to <f-f_45>=0.51+0.26-0.25 and
+f_h=4.73+2.17-2.05, whilst for clustered galaxies the signal is consistent with
+zero. (abridged)",1206.4304v1
+2012-07-06,Analytical Solutions to the Mass-Anisotropy Degeneracy with Higher Order Jeans Analysis: A General Method,"The Jeans analysis is often used to infer the total density of a system by
+relating the velocity moments of an observable tracer population to the
+underlying gravitational potential. This technique has recently been applied in
+the search for Dark Matter in objects such as dwarf spheroidal galaxies where
+the presence of Dark Matter is inferred via stellar velocities. A precise
+account of the density is needed to constrain the expected gamma ray flux from
+DM self-annihilation and to distinguish between cold and warm dark matter
+models. Unfortunately the traditional method of fitting the second order Jeans
+equation to the tracer dispersion suffers from an unbreakable degeneracy of
+solutions due to the unknown velocity anisotropy of the projected system. To
+tackle this degeneracy one can appeal to higher moments of the Jeans equation.
+By introducing an analog to the Binney anisotropy parameter at fourth order,
+beta' we create a framework that encompasses all solutions to the fourth order
+Jeans equations rather than those in the literature that impose unnecessary
+correlations between anisotropy of second and fourth order moments. The
+condition beta' = f(beta) ensures that the degeneracy is lifted and we
+interpret the separable augmented density system as the order-independent case
+beta'= beta. For a generic choice of beta' we present the line of sight
+projection of the fourth moment and how it could be incorporated into a joint
+likelihood analysis of the dispersion and kurtosis. Having presented the
+mathematical framework, we then use it to develop a statistical method for the
+purpose of placing constraints on dark matter density parameters from discrete
+velocity data. The method is tested on simulated dwarf spheroidal data sets
+leading to results which motivate study of real dwarf spheroidal data sets.",1207.1709v3
+2012-09-04,Heavy-Flavour Production in Pb-Pb collisions at the LHC with ALICE,"Results on open heavy-flavour production in Pb-Pb collisions at sqrt{s_NN} =
+2.76 TeV measured with ALICE at the LHC are presented. The nuclear modification
+factors, extracted in three different channels, show a strong suppression in
+central collisions. The measured D-meson azimuthal anisotropy indicates a
+non-zero v2, which is similar to the one of charged hadrons.",1209.0630v1
+2012-09-25,Cosmic Ray Physics with the IceCube Observatory,"The IceCube Neutrino Observatory with its 1-km^3 in-ice detector and the
+1-km^2 surface detector (IceTop) constitutes a three-dimensional cosmic ray
+detector well suited for general cosmic ray physics. Various measurements of
+cosmic ray properties, such as energy spectra, mass composition and
+anisotropies, have been obtained from analyses of air showers at the surface
+and/or atmospheric muons in the ice.",1209.5610v1
+2012-10-29,Orientation Sensitive Terahertz Resonances Observed in Protein Crystals,"A method is presented for measuring anisotropic THz response for small
+crystals, Crystal Anisotropy Terahertz Microscopy (CATM). Sucrose CATM
+measurements find the expected anisotropic phonon resonances. CATM measurements
+of protein crystals find the expected broadband water absorption is suppressed
+and strong orientation and hydration dependent resonant features.",1210.7531v1
+2012-12-12,"Comment on the ""Excess ellipticity of hot and cold spots WMAP data?"" by Berntsen, E. and Hansen, F.K","The recent paper by Berntsen and Hansen devoted to the analysis of
+elliptic-ity of anisotropies in CMB maps, distorts some statements of previous
+studies, misses relevant papers, along with superficial comparison of the
+results (in part of definitions, the role of noise, angular resolution, model
+parameters).",1212.2718v1
+2013-01-21,The anisotropic distribution of the interacting electrons,"The distribution function for a system of interacting electrons in metals is
+multivalent in a certain region of wave vectors. One solution among many is
+isotropic. For other solutions the distribution of electrons over the wave
+vectors is anisotropic. In the simplest case, the anisotropy arises as a result
+of the repulsion between electrons in states with the wave vectors $\bf k$ and
+$-\hh\bf k$.",1301.4711v1
+2013-01-30,Anisotropic branes,"We present a class of anisotropic brane configurations which shows BKL
+oscillations near their cosmological singularities. Near horizon limits of
+these solutions represent Kasner space embedded in AdS background. Dynamical
+probe branes in these geometries inherit anisotropies from the background.
+Amusingly, for a probe M5 brane, we find that there exists a parameter region
+where three of its world-volume directions expand while the rest contract.",1301.7194v1
+2013-02-19,TASI Lectures on Cosmological Perturbations,"We present a self-contained summary of the theory of linear cosmological
+perturbations. We emphasize the effect of the six parameters of the minimal
+cosmological model, first, on the spectrum of Cosmic Microwave Background
+temperature anisotropies, and second, on the linear matter power spectrum. We
+briefly review at the end the possible impact of a few non-minimal dark matter
+and dark energy models.",1302.4640v1
+2013-02-20,The Velocity Anisotropy of Distant Milky Way Halo Stars from Hubble Space Telescope Proper Motions,"Based on long baseline (5-7 years) multi-epoch HST/ACS photometry, used
+previously to measure the proper motion of M31, we present the proper motions
+(PMs) of 13 main-sequence Milky Way halo stars. The sample lies at an average
+distance of r ~24 kpc from the Galactic center, with a root-mean-square spread
+of 6 kpc. At this distance, the median PM accuracy is 5 km/s. We devise a
+maximum likelihood routine to determine the tangential velocity ellipsoid of
+the stellar halo. The velocity second moments in the directions of the Galactic
+(l,b) system are < vl^2 >^{1/2} = 123 (+29, -23) km/s, and < vb^2 >^{1/2} = 83
+(+24, -16) km/s. We combine these results with the known line-of-sight second
+moment, < vlos^2 >^{1/2} = 105 \pm 5$ km/s, at this < r > to study the velocity
+anisotropy of the halo. We find approximate isotropy between the radial and
+tangential velocity distributions, with anisotropy parameter beta = 0.0 (+0.2,
+-0.4). Our results suggest that the stellar halo velocity anisotropy out to r ~
+30 kpc is less radially biased than solar neighborhood measurements. This is
+opposite to what is expected from violent relaxation, and may indicate the
+presence of a shell-type structure at r ~ 24 kpc. With additional multi-epoch
+HST data, the method presented here has the ability to measure the transverse
+kinematics of the halo for more stars, and to larger distances. This can yield
+new improved constraints on the stellar halo formation mechanism, and the mass
+of the Milky Way.",1302.5111v1
+2013-03-18,Chaotic inflation in supergravity and cosmic string production,"We describe a simple model of chaotic inflation in supergravity where one can
+easily tune not only the basic cosmological parameters such as n_{s}, r, and
+f_NL, but also a possible (subdominant) cosmic string contribution to the CMB
+anisotropy.",1303.4435v1
+2013-03-25,Morphogenesis of defects and tactoids during isotropic-nematic phase transition in self-assembled lyotropic chromonic liquid crystals,"We explore the structure of nuclei and topological defects in the first-order
+phase transition between the nematic (N) and isotropic (I) phases in lyotropic
+chromonic liquid crystals (LCLCs). The LCLCs are formed by self-assembled
+molecular aggregates of various lengths and show a broad biphasic region. The
+defects emerge as a result of two mechanisms. 1) Surface anisotropy mechanism
+that endows each N nucleus (tactoid) with topological defects thanks to
+preferential (tangential) orientation of the director at the closed I-N
+interface, and 2) Kibble mechanism with defects forming when differently
+oriented N tactoids merge with each other. Different scenarios of phase
+transition involve positive (N-in-I) and negative (I-in-N) tactoids with
+non-trivial topology of the director field and also multiply connected
+tactoids-in-tactoids configurations. The closed I-N interface limiting a
+tactoid shows a certain number of cusps; the lips of the interface on the
+opposite sides of the cusp make an angle different from pi. The N side of each
+cusp contains a point defect-boojum. The number of cusps shows how many times
+the director becomes perpendicular to the I-N interface when one
+circumnavigates the closed boundary of the tactoid. We derive conservation laws
+that connect the number of cusps c to the topological strength m of defects in
+the N part of the simply-connected and multiply-connected tactoids. We
+demonstrate how the elastic anisotropy of the N phase results in non-circular
+shape of the disclination cores. A generalized Wulff construction is used to
+derive the shape of I and N tactoids as the function of I-N interfacial tension
+anisotropy in the frozen director field of various topological charges m. The
+complex shapes and structures of tactoids and topological defects demonstrate
+an important role of surface anisotropy in morphogenesis of phase transitions
+in liquid crystals.",1303.6239v1
+2013-03-29,On the Depolarization Factors for Anisotropic Ellipsoids in Anisotropic Media,"A definition of depolarization factors for anisotropic ellipsoid in an
+anisotropic medium is considered. The expressions for these factors are
+derived, which generalize some results known for special cases, and differences
+from the usual depolarization factors for ellipsoid in isotropic medium are
+described. The concept of ""reduced"" ellipsoid, allowing visually describe the
+effect of the medium anisotropy on depolarization is also introduced.",1303.7341v1
+2013-04-02,Cosmological anisotropy from non-comoving dark matter and dark energy,"We consider a cosmological model in which the two major fluid components of
+the Universe, dark energy and dark matter, flow with distinct four-velocities.
+This cosmological configuration is equivalent to a single anisotropic fluid,
+expanding with a four-velocity that is an appropriate combination of the two
+fluid four-velocities. The energy density of the single cosmological fluid is
+larger than the sum of the energy densities of the two perfect fluids, i.e.,
+dark energy and dark matter, respectively, and contains a correction term due
+to the anisotropy generated by the differences in the four-velocities.
+Furthermore, the gravitational field equations of the two-fluid anisotropic
+cosmological model are obtained for a Bianchi type I geometry. By assuming that
+the non-comoving motion of the dark energy and dark matter induces small
+perturbations in the homogeneous and isotropic
+Friedmann-Lemaitre-Robertson-Walker type cosmological background, and that the
+anisotropy parameter is small, the equations of the cosmological perturbations
+due to the non-comoving nature of the two major components are obtained. The
+time evolution of the metric perturbations is explicitly obtained for the cases
+of the exponential and power law background cosmological expansion. Therefore,
+if there is a slight difference between the four-velocities of the dark energy
+and dark matter, the Universe would acquire some anisotropic characteristics,
+and its geometry will deviate from the standard FLRW one. In fact, the recent
+Planck results show that the presence of an intrinsic large scale anisotropy in
+the Universe cannot be excluded {\it a priori}, so that the model presented in
+this work can be considered as a plausible and viable working hypothesis.",1304.0757v3
+2013-05-13,ALICE status and plans,"The ALICE experiment has been running successfully since 2010 and made an
+impressive progress towards understanding of hot and dense QCD matter produced
+in heavy ion collisions at LHC energies. Recent results on identified particle
+spectra, azimuthal anisotropy, heavy flavour and quarkonium production in Pb-Pb
+collisions at sqrt(s_NN) = 2.76 TeV are presented. First results on p-Pb
+collisions and ALICE upgrade plans are briefly reviewed.",1305.2804v1
+2013-05-21,Transport of spin-anisotropy without spin currents,"We revisit the transport of spin-degrees of freedom across an electrically
+and thermally biased tunnel junction between two ferromagnets with
+non-collinear magnetizations. Besides the well-known charge and spin currents
+we show that a non-zero spin-quadrupole current flows between the ferromagnets.
+This tensor-valued current describes the non-equilibrium transport of
+spin-anisotropy relating to both local and non-local multi-particle spin
+correlations of the circuit. This quadratic spin-anisotropy, quantified in
+terms of the spin-quadrupole moment, is fundamentally a two-electron quantity.
+In spin-valves with an embedded quantum dot such currents have been shown to
+result in a quadrupole accumulation that affects the measurable quantum dot
+spin and charge dynamics. The spin-valve model studied here allows fundamental
+questions about spin-quadrupole storage and transport to be worked out in
+detail, while ignoring the detection by a quantum dot. This physical
+understanding of this particular device is of importance for more complex
+devices where spin-quadrupole transport can be detected. We demonstrate that,
+as far as storage and transport are concerned, the spin anisotropy is only
+partly determined by the spin polarization. In fact, for a thermally biased
+spin-valve the charge- and spin-current may vanish, while a pure exchange
+spin-quadrupole current remains, which appears as a fundamental consequence of
+Pauli's principle. We extend the real-time diagrammatic approach to efficiently
+calculate the average of multi-particle spin-observables, in particular the
+spin-quadrupole current. Although the paper addresses only leading order and
+spin-conserving tunneling we formulate the technique for arbitrary order in an
+arbitrary, spin-dependent tunnel coupling in a way that lends itself to
+extension to quantum-dot spin-valve structures.",1305.4843v1
+2013-05-24,Magnetic field amplification and evolution in turbulent collisionless MHD: an application to the ICM,"The amplification and maintenance of the observed magnetic fields in the ICM
+are usually attributed to the turbulent dynamo action. This is generally
+derived employing a collisional MHD model. However, in the ICM the ion mean
+free path between collisions is of the order of the dynamical scales, thus
+requiring a collisionless MHD description. Unlike collisional MHD simulations,
+our study uses an anisotropic plasma pressure with respect to the direction of
+the local magnetic field, which brings the plasma within a parameter space
+where collisionless instabilities should take place. Within the adopted model
+these instabilities are contained at bay through the relaxation term of the
+pressure anisotropy which simulates the feedback of the mirror and firehose
+instabilities. This relaxation acts to get the plasma distribution function
+consistent with the empirical studies of collisionless plasmas. Our 3D
+numerical simulations of forced transonic turbulence motivated by modeling of
+the turbulent ICM are performed for different initial values of the magnetic
+field intensity, and different relaxation rates of the pressure anisotropy. We
+found that in the high beta plasma regime corresponding to the ICM conditions,
+a fast anisotropy relaxation rate gives results which are similar to the
+collisional-MHD model as far as the statistical properties of the turbulence
+are concerned. Also, the amplification of seed magnetic fields due to the
+turbulent dynamo action is similar to the collisional-MHD model. Our
+simulations that do not employ the anisotropy relaxation deviate significantly
+from the collisional-MHD results, and show more power at the small-scale
+fluctuations of both density and velocity representing the results of the
+instabilities. For these simulations the large scale fluctuations in the
+magnetic field are mostly suppressed and the turbulent dynamo fails in
+amplifying seed magnetic fields.",1305.5654v1
+2013-06-23,Searching For Anisotropic Gravitational-wave Backgrounds Using Pulsar Timing Arrays,"We present the results of simulated injections testing the first Bayesian
+search-pipeline capable of investigating the angular-structure of a
+gravitational-wave (GW) background influencing pulsar signals. A stochastic
+background of GWs from the incoherent superposition of many inspiraling
+supermassive black hole binaries at nHz frequencies is likely to be the
+dominant GW signal detectable by pulsar timing arrays (PTAs). Even though one
+might expect a background composed of a high-redshift cosmological population
+of sources to be fairly isotropic, deviations from isotropy may be indicative
+of local GW hotspots or some form of continuous anisotropy in the
+angular-distribution of GW-power. A GWB induces time-of-arrival deviations in
+pulsar signals which are correlated between separated pulsars. In an isotropic
+background this cross-correlation follows a distinctive relationship, known as
+the Hellings and Downs curve, that depends only on the angular separation of
+the pulsars. If the background is anisotropic, the cross-correlation is
+different, but predictable, and also depends on the absolute position of the
+pulsars. By simulating datasets containing GWBs with various anisotropic
+configurations, we have explored the prospects for constraining anisotropy
+using near future data. We find that at moderate to high signal to noise ratio
+the assumption of isotropy is no longer an appropriate description of the
+simulated background. Furthermore, we can recover the nature of the injected
+anisotropy in a Bayesian parameter-estimation search, and propose a prior on
+the anisotropy search-space motivated by the physicality of the implied
+distribution of sources.",1306.5395v2
+2013-08-20,Super-intense highly anisotropic optical transitions in anisotropic quantum dots,"Coulomb interaction among electrons is found to have profound effects on the
+electronic properties of anisotropic quantum dots in a perpendicular external
+magnetic field, and in the presence of the Rashba spin-orbit interaction. This
+is more evident in optical transitions, which we find in this system to be
+highly anisotropic and super-intense, in particular, for large values of the
+anisotropy parameter.",1308.4369v1
+2013-10-22,Overview of ALICE results,"Selected ALICE results on the global event properties, particle spectra,
+azimuthal anisotropy, heavy flavour and quarkonium production in Pb-Pb
+collisions at sqrt(s_NN) = 2.76 TeV are presented. First results on p-Pb
+collisions at sqrt(s_NN) = 5.02 TeV are briefly reviewed.",1310.5819v1
+2014-01-02,Low temperature ordering in easy-axis $S=1$ kagome and triangular lattice antiferromagnets,"A brief review is provided of earlier work on the low temperature phases of
+$S=1$ kagome and triangular lattice antiferromagnets in which there is
+sufficiently strongly single-ion anisotropy $D$ that dominates over the
+antiferromagnetic exchange $J$.",1401.0371v1
+2014-01-07,"The SLUGGS Survey: Breaking degeneracies between dark matter, anisotropy and the IMF using globular cluster subpopulations in the giant elliptical NGC 5846","We study the mass and anisotropy distribution of the giant elliptical galaxy
+NGC 5846 using stars, as well as the red and blue globular cluster (GC)
+subpopulations. We break degeneracies in the dynamical models by taking
+advantage of the different phase space distributions of the two GC
+subpopulations to unambiguously constrain the mass of the galaxy and the
+anisotropy of the GC system. Red GCs show the same spatial distribution and
+behaviour as the starlight, whereas blue GCs have a shallower density profile,
+a larger velocity dispersion and a lower kurtosis, all of which suggest a
+different orbital distribution. We use a dispersion-kurtosis Jeans analysis and
+find that the solutions of separate analyses for the two GC subpopulations
+overlap in the halo parameter space. The solution converges on a massive dark
+matter halo, consistent with expectations from $\Lambda$CDM and WMAP7 cosmology
+in terms of virial mass ($\log M_{DM} \sim13.3 M_{sun}$) and concentration
+($c_{vir}\sim8$). This is the first such analysis that solves the dynamics of
+the different GC subpopulations in a self-consistent manner. Our method
+improves the uncertainties on the halo parameter determination by a factor of
+two and opens new avenues for the use of elliptical galaxy dynamics as tests of
+predictions from cosmological simulations. The implied stellar mass-to-light
+ratio derived from the dynamical modelling is fully consistent with a Salpeter
+initial mass function (IMF) and rules out a bottom light IMF. The different GC
+subpopulations show markedly distinct orbital distributions at large radii,
+with red GCs having an anisotropy parameter $\beta\sim0.4$ outside $\sim3R_e$,
+and the blue GCs having $\beta\sim0.15$ at the same radii, while centrally
+($\sim1R_e$) they are both isotropic. We discuss the implications of our
+findings within the two-phase formation scenario for early-type galaxies.",1401.1501v1
+2014-01-17,Dynamical Models of Elliptical Galaxies -- I. Simple Methods,"We study dynamical models for elliptical galaxies, deriving the projected
+kinematic profiles in a form that is valid for general surface-brightness
+profiles and (spherical) total mass profiles, without the need for any explicit
+deprojection. We then show that an almost flat rotation curve, combined with
+modest velocity anisotropy, is already sufficient to recover the kinematic
+profiles of nearby ellipticals. As an application, we provide two different
+sets of mass estimators for elliptical galaxies, based on either the velocity
+dispersion at a specific location near the effective radius, or the
+aperture-averaged velocity dispersion. In the large aperture (virial) limit,
+mass estimators are naturally independent of anisotropy. The spherical mass
+enclosed within the effective radius $R_{\rm e}$ can be estimated as $2.4
+R_{\rm e} \langle \sigma^{2}_{\rm p} \rangle/ G$, where $\langle \sigma^2_{\rm
+p} \rangle$ is the average of the squared velocity dispersion over a finite
+aperture. This formula does not depend on assumptions such as
+mass-follows-light, and is a compromise between the cases of small and large
+apertures sizes. Its general agreement with results from other methods in the
+literature makes it a reliable means to infer masses in the absence of detailed
+kinematic information. If on the other hand the velocity dispersion profile is
+available, tight mass estimates can be found that are independent of the
+mass-model and anisotropy profile (within $\approx$ 10% accuracy). Explicit
+formulae are given for small anisotropy, large radii and/or power-law total
+densities. Motivated by recent observational claims, we also discuss the issue
+of weak homology of elliptical galaxies, emphasizing the interplay between
+morphology and orbital structure.",1401.4462v2
+2014-01-30,CMB statistical anisotropy from noncommutative gravitational waves,"Primordial statistical anisotropy is a key indicator to investigate early
+Universe models and has been probed by the cosmic microwave background (CMB)
+anisotropies. In this paper, we examine tensor-mode CMB fluctuations generated
+from anisotropic gravitational waves, parametrised by $P_h({\bf k}) =
+P_h^{(0)}(k) [ 1 + \sum_{LM} f_L(k) g_{LM} Y_{LM} (\hat{\bf k}) ]$, where
+$P_h^{(0)}(k)$ is the usual scale-invariant power spectrum. Such anisotropic
+tensor fluctuations may arise from an inflationary model with noncommutativity
+of fields. It is verified that in this model, an isotropic component and a
+quadrupole asymmetry with $f_0(k) = f_2(k) \propto k^{-2}$ are created and
+hence highly red-tilted off-diagonal components arise in the CMB power spectra,
+namely $\ell_2 = \ell_1 \pm 2$ in $TT$, $TE$, $EE$ and $BB$, and $\ell_2 =
+\ell_1 \pm 1$ in $TB$ and $EB$. We find that B-mode polarisation is more
+sensitive to such signals than temperature and E-mode polarisation due to the
+smallness of large-scale cosmic variance and we can potentially measure $g_{00}
+= 30$ and $g_{2M} = 58$ at 68% CL in a cosmic-variance-limited experiment. Such
+a level of signal may be measured in a PRISM like experiment, while the
+instrumental noise contaminates it in the $Planck$ experiment. These results
+imply that it is impossible to measure the noncommutative parameter if it is
+small enough for the perturbative treatment to be valid. Our formalism and
+methodology for dealing with the CMB tensor statistical anisotropy are general
+and straightforwardly applicable to other early Universe models.",1401.7936v2
+2014-03-20,Weak solutions of the Stochastic Landau-Lifschitz Equations with non-zero anisotrophy energy,"We study a Stochastic Landau-Lifschitz Equation with non-zero anisotrophy
+energy and multidimensional noise. The existence and some regularities of weak
+solution have been proved.",1403.5220v2
+2014-05-08,Azimuthal anisotropy of D meson production in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV,"The production of the prompt charmed mesons $D^0$, $D^+$ and $D^{*+}$
+relative to the reaction plane was measured in Pb-Pb collisions at a
+centre-of-mass energy per nucleon-nucleon collision of $\sqrt{s_{\rm NN}} =
+2.76$ TeV with the ALICE detector at the LHC. D mesons were reconstructed via
+their hadronic decays at central rapidity in the transverse momentum ($p_{\rm
+T}$) interval of 2-16 GeV/$c$. The azimuthal anisotropy is quantified in terms
+of the second coefficient $v_2$ in a Fourier expansion of the D meson azimuthal
+distribution, and in terms of the nuclear modification factor $R_{\rm AA}$,
+measured in the direction of the reaction plane and orthogonal to it. The $v_2$
+coefficient was measured with three different methods and in three centrality
+classes in the interval 0-50%. A positive $v_2$ is observed in mid-central
+collisions (30-50% centrality class), with an mean value of
+$0.204_{-0.036}^{+0.099}$ (tot.unc.) in the interval $2 < p_{\rm T} < 6$
+GeV/$c$, which decreases towards more central collisions (10-30% and 0-10%
+classes). The positive $v_2$ is also reflected in the nuclear modification
+factor, which shows a stronger suppression in the direction orthogonal to the
+reaction plane for mid-central collisions. The measurements are compared to
+theoretical calculations of charm quark transport and energy loss in
+high-density strongly-interacting matter at high temperature. The models that
+include substantial elastic interactions with an expanding medium provide a
+good description of the observed anisotropy. However, they are challenged to
+simultaneously describe the strong suppression of high-$p_{\rm T}$ yield of D
+mesons in central collisions and their azimuthal anisotropy in non-central
+collisions.",1405.2001v2
+2014-08-14,Utilizing wind in spatial covariance,"This work develops a covariance function which allows for a stronger spatial
+correlation for pairs of points in the direction of a vector such as wind and
+weaker for pairs which are perpendicular to it. It derives a simple covariance
+function by stretching the space along the wind axes (upwind and across wind
+axes). It is shown that this covariance function is anisotropy in the original
+space and the functions is explicitly calculated.",1408.3174v1
+2014-09-05,Simulations for a next-generation UHECR observatory,"We explore the potential of a future, ultra-high energy cosmic ray (UHECR)
+experiment, that is able to overcome the limitation of low statistics, to
+detect anisotropy in the arrival directions of UHECRs. We concentrate on the
+lower energy range of future instruments (E > 50 EeV), where, if the UHECR
+source number density is not too low, the sources should be numerous enough to
+imprint a clustering pattern in the sky, and thus possibly in the UHECR arrival
+directions. Under these limits, the anisotropy signal should be dominated by
+the clustering of astrophysical sources per-se in the large-scale structures,
+and not the clustering of events around individual sources. We study the
+potential for a statistical discrimination between different astrophysical
+models which we parametrise by the number density of UHECR sources, the
+possible bias of the UHECR accelerators with respect to the galaxy
+distribution, and the unknown fraction of UHECRs that have been deflected by
+large angles. We demonstrate that an order-of-magnitude increase in statistics
+would allow to discriminate between a variety of astrophysical models, provided
+that a sub-sample of light elements can be extracted, and that it represents at
+least ~70% of the overall flux, sensitive to the UHECR source number density.
+Even without knowledge of the composition, an anisotropy at the 99.7% level
+should be detectable when the number of detected events exceeds 2000 beyond 50
+EeV, as long as the composition is proton dominated, and the number density of
+UHECR sources is relatively high. If the UHECR sources are strongly biased
+relative to the galaxy distribution, as are for example galaxy clusters, an
+anisotropy at the 99.7% should be detectable once the number of detected events
+exceeds 1000, if the fraction of protons at the highest energies is ~60% or
+higher.",1409.1925v2
+2014-10-31,Anisotropic flow from hard partons in ultra-relativistic nuclear collisions,"Anisotropies of hadronic distribution in nuclear collisions are used for
+determination of properties of the nuclear matter. At the LHC it is important
+to account for the contribution to the flow due to momentum transferred from
+hard partons to the quark-gluon plasma.",1410.8711v1
+2014-12-02,Collective modes in anisotropic double layer systems,"We study collective modes in anisotropic double layer systems. To this end,
+we derive a zero-$T$ dynamic polarization function for a conductor with a
+paraboloidal dispersion. Following this, we demonstrate the dependence of the
+plasmonic modes on the relative orientation, doping, and system anisotropy.",1412.0811v1
+2014-12-19,"Monotonicity formulae and classification results for singular, degenerate, anisotropic PDEs","We consider possibly degenerate and singular elliptic equations in a possibly
+anisotropic medium.
+  We obtain monotonicity results for the energy density, rigidity results for
+the solutions and classification results for the
+singularity/degeneracy/anisotropy allowed.
+  As far as we know, these results are new even in the case of non-singular and
+non-degenerate anisotropic equations.",1412.6561v1
+2015-02-16,Anisotropy of third-order structure functions in MHD turbulence,"The measure of the third-order structure function, Y, is employed in the
+solar wind to compute the cascade rate of turbulence. In the absence of a mean
+field B0=0, Y is expected to be isotropic (radial) and independent of the
+direction of increments, so its measure yields directly the cascade rate. For
+turbulence with mean field, as in the solar wind, Y is expected to become more
+two dimensional (2D), that is, to have larger perpendicular components, loosing
+the above simple symmetry. To get the cascade rate one should compute the flux
+of Y, which is not feasible with single-spacecraft data, thus measurements rely
+upon assumptions about the unknown symmetry. We use direct numerical
+simulations (DNS) of magneto-hydrodynamic (MHD) turbulence to characterize the
+anisotropy of Y. We find that for strong guide field B0=5 the degree of
+two-dimensionalization depends on the relative importance of shear and pseudo
+polarizations (the two components of an Alfv\'en mode in incompressible MHD).
+The anisotropy also shows up in the inertial range. The more Y is 2D, the more
+the inertial range extent differs along parallel and perpendicular directions.
+We finally test the two methods employed in observations and find that the
+so-obtained cascade rate may depend on the angle between B0 and the direction
+of increments. Both methods yield a vanishing cascade rate along the parallel
+direction, contrary to observations, suggesting a weaker anisotropy of solar
+wind turbulence compared to our DNS. This could be due to a weaker mean field
+and/or to solar wind expansion.",1502.04705v2
+2015-03-16,The benchmark black hole in NGC 4258: dynamical models from high-resolution two-dimensional stellar kinematics,"NGC 4258 is the galaxy with the most accurate (maser-based) determination for
+the mass of the supermassive black hole (SMBH) in its nucleus. In this work we
+present a two-dimensional mapping of the stellar kinematics in the inner 3.0 x
+3.0 arcsec = 100 x 100 pc of NGC 4258 using adaptative-optics observations
+obtained with the Near-Infrared Integral Field Spectrograph of the GEMINI North
+telescope at a 0.11 arcsec (4 pc) angular resolution. The observations resolve
+the radius of influence of the SMBH, revealing an abrupt increase in the
+stellar velocity dispersion within 10 pc from the nucleus, consistent with the
+presence of a SMBH there. Assuming that the galaxy nucleus is in a steady state
+and that the velocity dispersion ellipsoid is aligned with a cylindrical
+coordinate system, we constructed a Jeans anisotropic dynamical model to fit
+the observed kinematics distribution. Our dynamical model assumes that the
+galaxy has axial symmetry and is constructed using the multi-gaussian expansion
+method to parametrize the observed surface brightness distribution. The Jeans
+dynamical model has three free parameters: the mass of the central SMBH, the
+mass-luminosity ratio of the galaxy and the anisotropy of the velocity
+distribution. We test two types of models: one with constant velocity
+anisotropy, and another with variable anisotropy. The model that best
+reproduces the observed kinematics was obtained considering that the galaxy has
+radially varying anisotropy, being the best-fitting parameters with 3$\sigma$
+significance $M_\bullet=4.8^{+0.8}_{-0.9}\times 10^7\,{\rm M_\odot}$ and
+$\Gamma_k = 4.1^{+0.4}_{-0.5}$. This value for the mass of the SMBH is just 25
+per cent larger than that of the maser determination and 50 per cent larger
+that a previous stellar dynamical determination obtained via Schwarzschild
+models.",1503.04540v2
+2015-04-30,Mass Models of Dwarf Spheroidal Galaxies with Variable Stellar Anisotropy. I. Jeans Analysis,"Using a flexible galactic model with variable stellar velocity anisotropy, I
+apply the classical Jeans mass modeling approach to the five dwarf spheroidal
+galaxies with the largest homogeneous datasets of stellar line-of-sight
+velocities (between 330 and 2500 stars per galaxy) -- Carina, Fornax, Leo~I,
+Sculptor, and Sextans. I carry out an exhaustive model parameter search,
+assigning absolute probabilities to each parameter combination. My main finding
+is that there is a well defined radius (unique for each galaxy) where the Jeans
+analysis constraints on the enclosed mass are tightest, and are much better
+than the constraints at previously suggested radii (e.g. 300~pc). For Carina,
+Fornax, Leo~I, Sculptor, and Sextans the enclosed DM mass is $0.94 \pm 0.20$
+(at 410~pc), $7.1 \pm 0.9$ (at 925~pc), $1.75 \pm 0.20$ (at 390~pc), $2.59 \pm
+0.42$ (at 435~pc), and $2.3 \pm 0.9$ (at 1035~pc), respectively (two-sigma
+uncertainties; in $10^7$~M$_\odot$ units). Local DM density has the tightest
+constraints at smaller (and also unique for each galaxy) radii. The largest
+central DM density constraint is for Sculptor: $\rho_0\gtrsim
+0.09$~$M_\odot$~pc$^{-3}$ (at two-sigma level). I show that the DM density
+logarithmic slope is totally unconstrained by the Jeans analysis at all the
+radii probed by the data (and not just at the center, as was demonstrated
+before). Stellar velocity anisotropy has only very weak constraints. In
+particular, pure central tangential anisotropy is ruled out at better than two
+sigma level for three dwarfs, and the data are consistent with the global
+stellar velocity isotropy for all the five galaxies.",1504.08273v1
+2015-06-11,Primordial Gravitational Waves Measurements and Anisotropies of CMB Polarization Rotation,"Searching for the signal of primordial gravitational waves in the B-modes
+(BB) power spectrum is one of the key scientific aims of the cosmic microwave
+background (CMB) polarization experiments. However, this could be easily
+contaminated by several foreground issues, such as the thermal dust emission.
+In this paper we study another mechanism, the cosmic birefringence, which can
+be introduced by a CPT-violating interaction between CMB photons and an
+external scalar field. Such kind of interaction could give rise to the rotation
+of the linear polarization state of CMB photons, and consequently induce the
+CMB BB power spectrum, which could mimic the signal of primordial gravitational
+waves at large scales. With the recent polarization data of BICEP2 and the
+joint analysis data of BICEP2/Keck Array and Planck, we perform a global
+fitting analysis on constraining the tensor-to-scalar ratio $r$ by considering
+the polarization rotation angle which can be separated into a background
+isotropic part and a small anisotropic part. Since the data of BICEP2 and Keck
+Array experiments have already been corrected by using the ""self-calibration""
+method, here we mainly focus on the effects from the anisotropies of CMB
+polarization rotation angle. We find that including the anisotropies in the
+analysis could slightly weaken the constraints on $r$, when using current CMB
+polarization measurements. We also simulate the mock CMB data with the
+BICEP3-like sensitivity. Very interestingly, we find that if the effects of the
+anisotropic polarization rotation angle can not be taken into account properly
+in the analysis, the constraints on $r$ will be dramatically biased. This
+implies that we need to break the degeneracy between the anisotropies of the
+CMB polarization rotation angle and the CMB primordial tensor perturbations, in
+order to measure the signal of primordial gravitational waves accurately.",1506.03526v1
+2015-06-24,A soft ellipsoid potential for biaxial molecules : Modeling and computer simulation,"A soft ellipsoid contact potential model for a pair of biaxial ellipsoidal
+molecules is proposed which considers the configuration dependent energy
+anisotropy explicitly along with their geometrical aspects. We performed
+Molecular Dynamics simulation study to generate both biaxial smectic and
+nematic phases using this new potential.",1506.07319v1
+2015-07-06,Novel method to obtain the anisotropic parameter of microcells,"In this paper we present a technique to measure the anisotropy parameter a
+suspension of microscopic particles. To estimate this parameter we use an
+integrating sphere as light collector, as well as a powder sample spherical
+particles of TiO$ _2 $ with an average diameter $ a = 0.25 \ \mu $m. The
+results for the sample of TiO$ _2$ are consistent with Mie calculations.",1507.01528v1
+2015-08-26,Current and field driven domain wall motion under influence of the Dzyaloshinsky-Moriya interaction,"A complete analytical description of the dynamics of current and field driven
+transverse domain walls under the influence of the Dzyaloshinsky-Moriya
+interaction using the $\phi - q$ model will be given. Five different scenarios
+will be observed where the Dzyaloshinsky-Moriya vector is either parallel or
+perpendicular to the easy axis anisotropy of the system and a direct reversal
+respectively precessional motion will be assumed.",1508.06372v1
+2015-09-09,On a sidereal time variation of the Lorentz force,"We consider a search for a sidereal time variation of the beam trajectory in
+the cyclotron motion in a static magnetic field. The combination of two beams
+moving in opposite directions could allow a test of the radius stability with
+sensitivity approaching $10^{-10}$. Such a level of variation of the Lorentz
+force, if it exists, would require a speed of light anisotropy on the level of
+$10^{-18}$.",1509.02754v1
+2015-10-03,Measurement of D-meson production in Pb-Pb collisions at the LHC with ALICE,"The measurement of D-meson production in heavy-ion collisions at LHC energy
+provides insights into the mechanisms of interaction of charm quarks in the hot
+and dense medium formed in these collisions. ALICE results on the D-meson
+nuclear modification factor and azimuthal anisotropy in Pb-Pb collisions at
+$\sqrt{s_{\rm NN}}=2.76$ TeV are presented.",1510.00825v1
+2015-10-21,Photon thermal Hall effect,"A near-field thermal Hall effect (i.e.Righi-Leduc effect) in networks of
+magneto-optical particles placed in a constant magnetic field is predicted.
+This many-body effect is related to a symmetry breaking in the system induced
+by the magnetic field which gives rise to preferential channels for the
+heat-transport by near-field interaction thanks to the particles anisotropy
+tuning.",1510.06103v2
+2015-11-05,Anisotropic Inflation and Cosmological Observations,"Recent observations opened up a new window on the inflationary model
+building. As it was firstly reported by the WMAP data, there may be some
+indications of statistical anisotropy on the CMB map, although the statistical
+significance of these findings are under debate. Motivated by these
+observations, people begun considering new inflationary models which may lead
+to statistical anisotropy. The simplest possible way to construct anisotropic
+inflation is to introduce vector fields. During the course of this thesis, we
+study models of anisotropic inflation and their observational implications such
+as power spectrum, bispectrum etc. Firstly we build a new model, which contains
+the gauge field which breaks the conformal invariance while preserving the
+gauge invariance. We show that in these kind of models, there can be an
+attractor phase in the evolution of the system when the back-reaction of the
+gauge field becomes important in the evolution of the inflaton field. We then
+study the cosmological perturbation theory in these kind of models. More
+specifically, we calculate the anisotropic corrections due to the presence of
+the vector field. We then generalize the separate universe formalism to our
+anisotropic set up and use it in some specific examples of anisotropic
+inflation. Finally, we connect the primordial anisotropies to the specific
+examples and to CMB observations. We calculate the TT, TE, TB, EB and BB
+correlation in the model of charged scalar field model and look for the unique
+signatures that the anisotropic inflation can have on the CMB map. Any future
+detection of these statistical anisotropies would rule out the isotropic FRW
+models.",1511.01683v1
+2015-12-23,Differential cosmic expansion and the Hubble flow anisotropy,"The Universe on scales $10-100~h^{-1}$ Mpc is dominated by a cosmic web of
+voids, filaments, sheets and knots of galaxy clusters. These structures
+participate differently in the global expansion of the Universe: from
+non-expanding clusters to the above average expansion rate of voids. In this
+paper we characterize Hubble expansion anisotropies in the COMPOSITE sample of
+4534 galaxies and clusters. We concentrate on the dipole and quadrupole in the
+rest frame of the Local Group. These both have statistically significant
+amplitudes. These anisotropies, and their redshift dependence, cannot be
+explained solely by a boost of the Local Group in the
+Friedmann-Lema\^itre-Robertson-Walker (FLRW) model which expands isotropically
+in the rest frame of the cosmic microwave background (CMB) radiation. We
+simulate the local expansion of the Universe with inhomogeneous Szekeres
+models, which match the standard FLRW model on $> 100~h^{-1}$ Mpc scales but
+exhibit nonkinematic relativistic differential expansion on small scales. We
+restrict models to be consistent with observed CMB temperature anisotropies,
+while simultaneously fitting the redshift variation of the Hubble expansion
+dipole. We include features to account for both the Local Void and the ""Great
+Attractor"". While this naturally accounts for the Hubble expansion and CMB
+dipoles, the simulated quadrupoles are smaller than observed. Further
+refinement to incorporate additional structures may improve this. This would
+enable a test of the hypothesis that some large angle CMB anomalies result from
+failing to treat the relativistic differential expansion of the background
+geometry, a natural feature of solutions to Einstein's equations not included
+in the current standard model of cosmology.",1512.07364v3
+2015-12-26,"Pressure-anisotropy-driven microturbulence and magnetic-field evolution in shearing, collisionless plasma","The nonlinear state of a high-beta collisionless plasma is investigated when
+an imposed linear shear amplifies or diminishes a uniform magnetic field,
+driving pressure anisotropies and hence firehose/mirror instabilities. The
+evolution of the resulting microscale turbulence is considered when the shear
+is switched off or reversed after one shear time (mimicking local behaviour of
+a macroscopic flow), so a new macroscale configuration is superimposed on the
+microscale state left behind by the previous one. There is a threshold value of
+plasma beta: when $\beta\ll\Omega/S$ (ion cyclotron frequency/shear rate), the
+emergence of firehose/mirror fluctuations driven unstable by shear and their
+disappearance when the shear is removed/reversed are quasi-instantaneous
+compared to the shear time, viz., the decay time of these fluctuations is
+$\sim\beta/\Omega \ll 1/S$ (this result follows from the free decay of the
+fluctuations being constrained by the same marginal-stability thresholds as
+their growth). In contrast, when $\beta\gtrsim\Omega/S$ (""ultra-high"" beta),
+the old microscale state can only be removed on the shear timescale. In this
+regime, driven firehose fluctuations grow secularly to order-unity amplitudes,
+compensating for the decay of the mean field and so pinning pressure anisotropy
+at marginal stability with no appreciable scattering of particles---which is
+unlike what happens at moderate $\beta$. When the shear reverses, the shearing
+away of this firehose turbulence compensates for the increase in the mean field
+and thus prevents growth of the pressure anisotropy, stopping the system from
+going mirror-unstable. Therefore, at ultra-high beta, the system stays close to
+the firehose threshold, the mirror instability is largely suppressed, while the
+mean magnetic energy barely changes at all. Implications for plasma dynamo and
+thus the origin of cosmic magnetism are discussed.",1512.08131v1
+2016-01-19,Dilepton production rate in a hot and magnetized quark-gluon plasma,"The differential multiplicity of dileptons in a hot and magnetized
+quark-gluon plasma, $\Delta_{B}\equiv dN_{B}/d^{4}xd^{4}q$, is derived from
+first principles. The constant magnetic field $B$ is assumed to be aligned in a
+fixed spatial direction. It is shown that the anisotropy induced by the $B$
+field is mainly reflected in the general structure of photon spectral density
+function. This is related to the imaginary part of the vacuum polarization
+tensor, $\mbox{Im}[\Pi^{\mu\nu}]$, which is derived in a first order
+perturbative approximation. As expected, the final analytical expression for
+$\Delta_{B}$ includes a trace over the product of a photonic part,
+$\mbox{Im}[\Pi^{\mu\nu}]$, and a leptonic part, ${\cal{L}}_{\mu\nu}$. It is
+shown that $\Delta_{B}$ consists of two parts, $\Delta_{B}^{\|}$ and
+$\Delta_{B}^{\perp}$, arising from the components $(\mu,\nu)=(\|,\|)$ and
+$(\mu,\nu)=(\perp,\perp)$ of $\mbox{Im}[\Pi^{\mu\nu}]$ and
+${\cal{L}}_{\mu\nu}$. Here, the transverse and longitudinal directions are
+defined with respect to the direction of the $B$ field. Combining
+$\Delta_{B}^{\|}$ and $\Delta_{B}^{\perp}$, a novel anisotropy factor $\nu_{B}$
+is introduced. Using the final analytical expression of $\Delta_{B}$, the
+possible interplay between the temperature $T$ and the magnetic field strength
+$eB$ on the ratio $\Delta_{B}/\Delta_{0}$ and $\nu_{B}$ is numerically studied.
+Here, $\Delta_{0}$ is the Born approximated dilepton multiplicity in the
+absence of external magnetic fields. It is, in particular, shown that for each
+fixed $T$ and $B$, in the vicinity of certain threshold energies,
+$\Delta_{B}\gg \Delta_{0}$ and $\Delta_{B}^{\perp}\gg \Delta_{B}^{\|}$. The
+latter anisotropy may be interpreted as one of the microscopic sources of the
+macroscopic anisotropies, reflecting themselves, e.g., in the elliptic
+asymmetry factor $v_{2}$ of dileptons.",1601.04887v3
+2016-02-01,Numerical Modelling of Disordered Magnetic Systems: La2-xSrxCoO4,"Magnetic properties of La2-xSrxCoO4 have been modelled using McPhase for
+different doping levels x. Footprints of different interactions, such as local
+single ion anisotropy and variations in the exchange interactions have been
+identified in the profile of the diffuse elastic neutron scattering cross
+section. The role of quantum fluctuations in the formation of the hourglass
+spectrum is discussed.",1602.00507v3
+2016-02-09,Excitonic terahertz absorption in semiconductors with effective-mass anisotropies,"A microscopic approach is developed to compute the excitonic properties and
+the corresponding terahertz response for semiconductors characterized by
+anisotropic effective masses. The approach is illustrated for the example of
+germanium where it is shown that the anisotropic electron mass in the L-valley
+leads to two distinct terahertz absorption resonances separated by 0.8 meV.",1602.02972v1
+2016-02-08,PIC Simulations of the Effect of Velocity Space Instabilities on Electron Viscosity and Thermal Conduction,"In low-collisionality plasmas, velocity-space instabilities are a key
+mechanism providing an effective collisionality for the plasma. We use
+particle-in-cell (PIC) simulations to study the interplay between electron and
+ion-scale velocity-space instabilities and their effect on electron pressure
+anisotropy, viscous heating, and thermal conduction. The adiabatic invariance
+of the magnetic moment in low-collisionality plasmas leads to pressure
+anisotropy, $p_{\perp,j} > p_{||,j}$, if the magnetic field $\vec{B}$ is
+amplified ($p_{\perp,j}$ and $p_{||,j}$ denote the pressure of species $j$
+[electron, ion] perpendicular and parallel to $\vec{B}$). If the resulting
+anisotropy is large enough, it can in turn trigger small-scale plasma
+instabilities. Our PIC simulations explore the nonlinear regime of the mirror,
+ion-cyclotron, and electron whistler instabilities, through continuous
+amplification of the magnetic field $|\vec{B}|$ by an imposed shear in the
+plasma. In the regime $1 \lesssim \beta_j \lesssim 20$ ($\beta_j \equiv 8\pi
+p_j/|\vec{B}|^2$), the saturated electron pressure anisotropy, $\Delta
+p_e/p_{||,e}$, is determined mainly by the (electron-lengthscale) whistler
+marginal stability condition, with a modest factor of $\sim 1.5-2$ decrease due
+to the trapping of electrons by the mirrors. We explicitly calculate the mean
+free path of the electrons and ions along the mean magnetic field and provide a
+simple physical prescription for the mean free path and thermal conductivity in
+low-collisionality $\beta_j \gtrsim 1$ plasmas. Our results imply that
+velocity-space instabilities likely decrease the thermal conductivity of plasma
+in the outer parts of massive, hot, galaxy clusters. We also discuss the
+implications of our results for electron heating and thermal conduction in
+low-collisionality accretion flows onto black holes, including Sgr A* in the
+Galactic Center.",1602.03126v2
+2016-03-11,Modeling SNR Cassiopeia A from the Supernova Explosion to its Current Age: The role of post-explosion anisotropies of ejecta,"The remnants of core-collapse supernovae (SNe) have complex morphologies that
+may reflect asymmetries and structures developed during the progenitor SN
+explosion. Here we investigate how the morphology of the SNR Cassiopeia A (Cas
+A) reflects the characteristics of the progenitor SN with the aim to derive the
+energies and masses of the post-explosion anisotropies responsible for the
+observed spatial distribution of Fe and Si/S. We model the evolution of Cas A
+from the immediate aftermath of the progenitor SN to the three-dimensional
+interaction of the remnant with the surrounding medium. The post-explosion
+structure of the ejecta is described by small-scale clumping of material and
+larger-scale anisotropies. The hydrodynamic multi-species simulations consider
+an appropriate post-explosion isotopic composition of the ejecta. The observed
+average expansion rate and shock velocities can be well reproduced by models
+with ejecta mass $M_{\rm ej}\approx 4M_{\odot}$ and explosion energy $E_{\rm
+SN}\approx 2.3\times 10^{51}$ erg. The post-explosion anisotropies (pistons)
+reproduce the observed distributions of Fe and Si/S if they had a total mass of
+$\approx 0.25\,M_{\odot}$ and a total kinetic energy of $\approx 1.5\times
+10^{50}$ erg. The pistons produce a spatial inversion of ejecta layers at the
+epoch of Cas A, leading to the Si/S-rich ejecta physically interior to the
+Fe-rich ejecta. The pistons are also responsible for the development of bright
+rings of Si/S-rich material which form at the intersection between the reverse
+shock and the material accumulated around the pistons during their propagation.
+Our result supports the idea that the bulk of asymmetries observed in Cas A are
+intrinsic to the explosion.",1603.03690v1
+2016-04-14,Sobolev and Lipschitz regularity for local minimizers of widely degenerate anisotropic functionals,"We prove higher differentiability of bounded local minimizers to some widely
+degenerate functionals, verifying superquadratic anisotropic growth conditions.
+In the two dimensional case, we prove that local minimizers to a model
+functional are locally Lipschitz continuous functions, without any restriction
+on the anisotropy.",1604.04189v1
+2015-09-24,Spectral Anisotropy of Elsässer Variables in Two Dimensional Wave-vector Space as Observed in the Fast Solar Wind Turbulence,"Intensive studies have been conducted to understand the anisotropy of solar
+wind turbulence. However, the anisotropy of Els\""asser variables
+($\textbf{Z}^\pm$) in 2D wave-vector space has yet to be investigated. Here we
+first verify the transformation based on the projection-slice theorem between
+the power spectral density PSD$_{2D}(k_\parallel,k_\perp )$ and the spatial
+correlation function CF$_{2D} (r_\parallel,r_\perp )$. Based on the application
+of the transformation to the magnetic field and the particle measurements from
+the WIND spacecraft, we investigate the spectral anisotropy of Els\""asser
+variables ($\textbf{Z}^\pm$), and the distribution of residual energy E$_{R}$,
+Alfv\'en ratio R$_{A}$ and Els\""asser ratio R$_{E}$ in the
+$(k_\parallel,k_\perp)$ space. The spectra PSD$_{2D}(k_\parallel,k_\perp )$ of
+$\textbf{B}$, $\textbf{V}$, and $\textbf{Z}_{major}$ (the larger of
+$\textbf{Z}^\pm$) show a similar pattern that PSD$_{2D}(k_\parallel,k_\perp )$
+is mainly distributed along a ridge inclined toward the $k_\perp$ axis. This is
+probably the signature of the oblique Alfv\'enic fluctuations propagating
+outwardly. Unlike those of $\textbf{B}$, $\textbf{V}$, and
+$\textbf{Z}_{major}$, the spectrum PSD$_{2D}(k_\parallel,k_\perp )$ of
+$\textbf{Z}_{minor}$ is distributed mainly along the $k_\perp$ axis. Close to
+the $k_\perp$ axis, $\left| {E}_{R}\right|$ becomes larger while R$_{A}$
+becomes smaller, suggesting that the dominance of magnetic energy over kinetic
+energy becomes more significant at small $k_\parallel$. R$_{E}$ is larger at
+small $k_\parallel$, implying that PSD$_{2D}(k_\parallel,k_\perp )$ of
+$\textbf{Z}_{minor}$ is more concentrated along the $k_\perp$ direction as
+compared to that of $\textbf{Z}_{major}$. The residual energy condensate at
+small $k_\parallel$ is consistent with simulation results in which E$_{R}$ is
+spontaneously generated by Alfv\'en wave interaction.",1604.07760v1
+2016-04-28,"Highly-anisotropic exchange interactions of $j_{\rm eff}=1/2$ iridium moments on the fcc lattice in La$_2B$IrO$_6$ ($B$ $=$ Mg, Zn)","We have performed inelastic neutron scattering (INS) experiments to
+investigate the magnetic excitations in the weakly distorted
+face-centered-cubic (fcc) iridate double perovskites La$_2$ZnIrO$_6$ and
+La$_2$MgIrO$_6$, which are characterized by A-type antiferromagnetic ground
+states. The powder inelastic neutron scattering data on these geometrically
+frustrated $j_{\rm eff}=1/2$ Mott insulators provide clear evidence for gapped
+spin wave excitations with very weak dispersion. The INS results and
+thermodynamic data on these materials can be reproduced by conventional
+Heisenberg-Ising models with significant uniaxial Ising anisotropy and sizeable
+second-neighbor ferromagnetic interactions. Such a uniaxial Ising exchange
+interaction is symmetry-forbidden on the ideal fcc lattice, so that it can only
+arise from the weak crystal distortions away from the ideal fcc limit. This may
+suggest that even weak distortions in $j_{\rm eff}=1/2$ Mott insulators might
+lead to strong exchange anisotropies. More tantalizingly, however, we find an
+alternative viable explanation of the INS results in terms of spin models with
+a dominant Kitaev interaction. In contrast to the uniaxial Ising exchange, the
+highly-directional Kitaev interaction is a type of exchange anisotropy which is
+symmetry-allowed even on the ideal fcc lattice. The Kitaev model has a magnon
+gap induced by quantum order-by-disorder, while weak anisotropies of the Kitaev
+couplings generated by the symmetry-lowering due to lattice distortions, can
+pin the order and enhance the magnon gap. Our findings highlight how even
+conventional magnetic orders in heavy transition metal oxides may be driven by
+highly-directional exchange interactions rooted in strong spin-orbit coupling.",1604.08431v1
+2016-06-12,Relativistic calculations of angular dependent photoemission time delay,"Angular dependence of photoemission time delay for the valence $np_{3/2}$ and
+$np_{1/2}$ subshells of Ar, Kr and Xe is studied in the dipole relativistic
+random phase approximation. Strong angular anisotropy of the time delay is
+reproduced near respective Cooper minima while the spin-orbit splitting affects
+the time delay near threshold.",1606.03780v1
+2016-07-06,Chirality of topological gap solitons in bosonic dimer chains,"We study gap solitons which appear in the topological gap of 1D bosonic dimer
+chains within the mean-field approximation. We find that such solitons have a
+non-trivial texture of the sublattice pseudospin. We reveal their chiral nature
+by demonstrating the anisotropy of their behavior in presence of a localized
+energy potential.",1607.01805v2
+2016-07-10,Eutectic colony formation in systems with interfacial energy anisotropy: A phase field study,"Instability of a binary eutectic solidification front to morphological
+perturbations due to rejection of a ternary impurity leads to the formation of
+eutectic colonies. Whereas, the instability dynamics and the resultant mi-
+crostructural features are reasonably well understood for isotropic systems,
+several experimental observations point to the existence of colonies in systems
+with anisotropic interfaces. In this study, we extend the un- derstanding of
+eutectic colonies to anisotropic systems, where only certain orientations of
+the solid-liquid or solid-solid interfaces are thermodynamically stable.
+Through phase field simulations in 2D and 3D, we have systematically probed the
+colony formation dynamics and the resulting microstructures, as functions of
+the pulling velocity and the relative orientation of the equilibrium interfaces
+with that of the imposed tempera- ture gradient. We find that in 2D, stabler
+finger spacings are selected with an increase in the magnitude of anisotropy
+introduced, either in the solid-liquid or in the solid-solid interface. The
+fingers have a well-defined orientation for the case of anisotropy in the
+solid-liquid interface, with no fixed orientations for the lamellae
+constituting the colony. For the case where anisotropy exists in the
+solid-solid interface, the lamellae tend to orient themselves along the
+direction of the imposed temperature gradient, with tilted solid-liquid
+interfaces from the horizontal. The 3D simulations reveal existence of eutectic
+spirals which might become tilted under certain orientations of the equilibrium
+interfaces. Our simulations are able to explain several key features observed
+in our experimantal studies of solidification in Ni-Al-Zr alloy.",1607.02722v3
+2016-08-25,The angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its Dark Matter interpretation,"The isotropic gamma-ray background arises from the contribution of unresolved
+sources, including members of confirmed source classes and proposed gamma-ray
+emitters such as the radiation induced by dark matter annihilation and decay.
+Clues about the properties of the contributing sources are imprinted in the
+anisotropy characteristics of the gamma-ray background. We use 81 months of
+Pass 7 Reprocessed data from the Fermi Large Area Telescope to perform a
+measurement of the anisotropy angular power spectrum of the gamma-ray
+background. We analyze energies between 0.5 and 500 GeV, extending the range
+considered in the previous measurement based on 22 months of data. We also
+compute, for the first time, the cross-correlation angular power spectrum
+between different energy bins. We find that the derived angular spectra are
+compatible with being Poissonian, i.e. constant in multipole. Moreover, the
+energy dependence of the anisotropy suggests that the signal is due to two
+populations of sources, contributing, respectively, below and above 2 GeV.
+Finally, using data from state-of-the-art numerical simulations to model the
+dark matter distribution, we constrain the contribution from dark matter
+annihilation and decay in Galactic and extragalactic structures to the measured
+anisotropy. These constraints are competitive with those that can be derived
+from the average intensity of the isotropic gamma-ray background. Data are
+available at https://www-glast.stanford.edu/pub_data/552.",1608.07289v2
+2016-08-29,"A discrete chemo-dynamical model of the giant elliptical galaxy NGC 5846: dark matter fraction, internal rotation and velocity anisotropy out to six effective radii","We construct a suite of discrete chemo-dynamical models of the giant
+elliptical galaxy NGC 5846. These models are a powerful tool to constrain both
+the mass distribution and internal dynamics of multiple tracer populations. We
+use Jeans models to simultaneously fit stellar kinematics within the effective
+radius $R_{\rm e}$, planetary nebula (PN) radial velocities out to $3\, R_{\rm
+e}$, and globular cluster (GC) radial velocities and colours out to $6\,R_{\rm
+e}$. The best-fitting model is a cored DM halo which contributes $\sim 10\%$ of
+the total mass within $1\,R_{\rm e}$, and $67\% \pm 10\%$ within $6\,R_{\rm
+e}$, although a cusped DM halo is also acceptable. The red GCs exhibit mild
+rotation with $v_{\rm max}/\sigma_0 \sim 0.3$ in the region $R > \,R_{\rm e}$,
+aligned with but counter-rotating to the stars in the inner parts, while the
+blue GCs and PNe kinematics are consistent with no rotation. The red GCs are
+tangentially anisotropic, the blue GCs are mildly radially anisotropic, and the
+PNe vary from radially to tangentially anisotropic from the inner to the outer
+region. This is confirmed by general made-to-measure models. The tangential
+anisotropy of the red GCs in the inner regions could stem from the preferential
+destruction of red GCs on more radial orbits, while their outer tangential
+anisotropy -- similar to the PNe in this region -- has no good explanation. The
+mild radial anisotropy of the blue GCs is consistent with an accretion
+scenario.",1608.08238v1
+2016-09-06,Numerical study of optimal partitioning problems in relation to an anisotropic perimeter,"We present a ${\Gamma}$-convergence approximation for the total anisotropic
+length of a partition. This theoretical result gives rise to a numerical method
+which allows the study of minimal partitions with respect to different
+anisotropies. We also give a numerical framework for the study of isoperimetric
+problems with density.",1609.01467v1
+2016-11-04,Second-harmonic generation as probe for structural and electronic properties of buried GaP/Si(001) interfaces,"Optical second-harmonic generation is demonstrated to be a sensitive probe of
+the buried interface between the lattice matched semiconductors gallium
+phosphide and silicon with (001) orientation. Rotational anisotropy
+measurements of SHG from GaP/Si show a strong isotropic component of the
+response not present for pure Si(001) or GaP(001). The strength of the
+overlaying anisotropic response directly correlates with the quality of the
+interface as determined by atomically resolved scanning transmission electron
+microscopy.Optical second-harmonic generation is demonstrated to be a sensitive
+probe of the buried interface between the lattice matched semiconductors
+gallium phosphide and silicon with (001) orientation. Rotational anisotropy
+measurements of SHG from GaP/Si show a strong isotropic component of the
+response not present for pure Si(001) or GaP(001). The strength of the
+overlaying anisotropic response directly correlates with the quality of the
+interface as determined by atomically resolved scanning transmission electron
+microscopy. Systematic comparison of samples fabricated with different growth
+modes in metal organic vapor phase epitaxy reveals that the anisotropy for
+different polarization combinations can be used as a selective fingerprint for
+the occurrence of anti-phase domains and twins. This all-optical technique can
+be applied as an {\it in-situ} and non-invasive monitor even during growth.
+Systematic comparison of samples fabricated with different growth modes in
+metal organic vapor phase epitaxy reveals that the anisotropy for different
+polarization combinations can be used as a selective fingerprint for the
+occurrence of anti-phase domains and twins. This all-optical technique can be
+applied as an {\it in-situ} and non-invasive monitor even during growth.",1611.01307v2
+2016-11-10,Anisotropic inflation with a non-minimally coupled electromagnetic field to gravity,"We consider the non-minimal model of gravity in $Y(R) F^2$-form. We
+investigate a particular case of the model, for which the higher order
+derivatives are eliminated but the scalar curvature $R$ is kept to be dynamical
+via the constraint $Y_RF_{mn}F^{mn} =-\frac{2}{\kappa^2}$. The effective fluid
+obtained can be represented by interacting electromagnetic field and vacuum
+depending on $Y(R)$, namely, the energy density of the vacuum tracks $R$ while
+energy density of the conventional electromagnetic field is dynamically scaled
+with the factor $\frac{Y(R)}{2}$. We give exact solutions for anisotropic
+inflation by assuming the volume scale factor of the Universe exhibits a
+power-law expansion. The directional scale factors do not necessarily exhibit
+power-law expansion, which would give rise to a constant expansion anisotropy,
+but expand non-trivially and give rise to a non-monotonically evolving
+expansion anisotropy that eventually converges to a non-zero constant. Relying
+on this fact, we discuss the anisotropic e-fold during the inflation by
+considering observed scale invariance in CMB and demanding the Universe to
+undergo the same amount of e-folds in all directions. We calculate the residual
+expansion anisotropy at the end of inflation, though as a result of
+non-monotonic behaviour of expansion anisotropy all the axes of the Universe
+undergo the same of amount of e-folds by the end of inflation. We also discuss
+the generation of the modified electromagnetic field during the first few
+e-folds of the inflation and its persistence against to the vacuum till end of
+inflation.",1611.03393v4
+2016-11-11,Statistics of Reconnection-Driven Turbulence,"Magnetic reconnection is a process that changes magnetic field topology in
+highly conducting fluids. Within the standard Sweet-Parker model, this process
+would be too slow to explain observations (e.g. solar flares). In reality, the
+process must be ubiquitous as astrophysical fluids are magnetized and motions
+of fluid elements necessarily entail crossing of magnetic frozen-in field lines
+and magnetic reconnection. In the presence of turbulence, the reconnection is
+independent of microscopic plasma properties, and may be much faster than
+previously thought, as proposed in Lazarian & Vishniac (1999) and tested in
+Kowal et al. (2009, 2012). However, the considered turbulence in the
+Lazarian-Vishniac model was imposed externally. In this work we consider
+reconnection-driven magnetized turbulence in realistic three-dimensional
+geometry initiated by stochastic noise. We demonstrate through numerical
+simulations that the stochastic reconnection is able to self-generate
+turbulence through interactions between its outflows. We analyze the
+statistical properties of velocity fluctuations using power spectra and
+anisotropy scaling, which demonstrates that the reconnection produces
+Kolmogorov-like turbulence, compatible with Goldreich-Sridhar (1995) model.
+Anisotropy statistics are, however, strongly affected by the dynamics of
+reconnection outflows. Once the broad turbulent region is formed, the typical
+anisotropy scaling $l_\parallel \propto l_\perp^{2/3}$ is formed, especially
+for high resolution models, were the broader range of scales is available. The
+decay of reconnection outflows to turbulent-like fluctuations, characterized by
+different anisotropy scalings, strongly depends on $\beta$ plasma. Moreover,
+the estimated reconnection rates are weakly dependent on the resolution,
+suggesting that no external processes are required to make reconnection fast.",1611.03914v2
+2016-11-25,Alignment of galaxies relative to their local environment in SDSS-DR8,"We study the alignment of galaxies relative to their local environment in
+SDSS-DR8 and, using these data, we discuss evolution scenarios for different
+types of galaxies. We defined a vector field of the direction of anisotropy of
+the local environment of galaxies. We summed the unit direction vectors of all
+close neighbours of a given galaxy in a particular way to estimate this field.
+We found the alignment angles between the spin axes of disc galaxies, or the
+minor axes of elliptical galaxies, and the direction of anisotropy. The
+distributions of cosines of these angles are compared to the random
+distributions to analyse the alignment of galaxies. Sab galaxies show
+perpendicular alignment relative to the direction of anisotropy in a sparse
+environment, for single galaxies and galaxies of low luminosity. Most of the
+parallel alignment of Scd galaxies comes from dense regions, from 2...3 member
+groups and from galaxies with low luminosity. The perpendicular alignment of S0
+galaxies does not depend strongly on environmental density nor luminosity; it
+is detected for single and 2...3 member group galaxies, and for main galaxies
+of 4...10 member groups. The perpendicular alignment of elliptical galaxies is
+clearly detected for single galaxies and for members of < 11 member groups; the
+alignment increases with environmental density and luminosity. We confirm the
+existence of fossil tidally induced alignment of Sab galaxies at low z. The
+alignment of Scd galaxies can be explained via the infall of matter to
+filaments. S0 galaxies may have encountered relatively massive mergers along
+the direction of anisotropy. Major mergers along this direction can explain the
+alignment of elliptical galaxies. Less massive, but repeated mergers are
+possibly responsible for the formation of elliptical galaxies in sparser areas
+and for less luminous elliptical galaxies.",1611.08378v1
+2016-12-23,Cosmic-Ray Anisotropies: A Review,"Important observational results have been recently reported on the angular
+distributions of cosmic rays (CRs) at all energies, calling into question the
+perception of CRs a decade ago. These results together with their in-progress
+interpretations are summarized in this short overview paper, following the
+contribution presented at the XXV European Cosmic Ray Symposium.",1612.08002v1
+2017-01-09,Orthogonal involutions and totally singular quadratic forms in characteristic two,"We associate to every central simple algebra with involution of orthogonal
+type in characteristic two a totally singular quadratic form which reflects
+certain anisotropy properties of the involution. It is shown that this
+quadratic form can be used to classify totally decomposable algebras with
+orthogonal involution. Also, using this form, a criterion is obtained for an
+orthogonal involution on a split algebra to be conjugated to the transpose
+involution.",1701.02169v1
+2017-01-13,Anisotropy in finite continuum percolation: Threshold estimation by Minkowski functionals,"We examine the interplay between anisotropy and percolation, i.e., the
+spontaneous formation of a system spanning cluster in an anisotropic model. We
+simulate an extension of a benchmark model of continuum percolation, the
+Boolean model, which is formed by overlapping grains. Here we introduce an
+orientation bias of the grains that controls the degree of anisotropy of the
+generated patterns. We analyze in the Euclidean plane the percolation
+thresholds above which percolating clusters in $x$- and in $y$-direction
+emerge. Only in finite systems, distinct differences between effective
+percolation thresholds for different directions appear. If extrapolated to
+infinite system sizes, these differences vanish independent of the details of
+the model. In the infinite system, the uniqueness of the percolating cluster
+guarantees a unique percolation threshold. While percolation is isotropic even
+for anisotropic processes, the value of the percolation threshold depends on
+the model parameters, which we explore by simulating a score of models with
+varying degree of anisotropy. To which precision can we predict the percolation
+threshold without simulations? We discuss analytic formulas for approximations
+(based on the excluded area or the Euler characteristic) and compare them to
+our simulation results. Empirical parameters from similar systems allow for
+accurate predictions of the percolation thresholds (with deviations of $<5\%$
+in our examples), but even without any empirical parameters, the explicit
+approximations from integral geometry provide, at least for the systems studied
+here, lower bounds that capture well the qualitative dependence of the
+percolation threshold on the system parameters (with deviations of
+$5\%$--$30\%$). As an outlook, we suggest further candidates for explicit and
+geometric approximations based on second moments of the so-called Minkowski
+functionals.",1701.03729v1
+2017-01-19,Influence of uniaxial single-ion anisotropy on the magnetic and thermal properties of Heisenberg antiferromagnets within unified molecular field theory,"The influence of uniaxial single-ion anisotropy -DSz^2 on the magnetic and
+thermal properties of Heisenberg antiferromagnets (AFMs) is investigated. The
+uniaxial anisotropy is treated exactly and the Heisenberg interactions are
+treated within unified molecular field theory (MFT) [Phys. Rev. B 91, 064427
+(1915)], where thermodynamic variables are expressed in terms of directly
+measurable parameters. The properties of collinear AFMs with ordering along the
+z axis (D > 0) in applied fields Hz = 0 are calculated versus D and temperature
+T. The high-field average magnetization per spin muz(Hz,D,T) is found, and the
+critical field Hc(D,T) is derived at which the second-order AFM to PM phase
+transition occurs. The magnetic properties of the spin-flop (SF) phase are
+calculated, including the zero-field properties TN(D) and mu(D,T). The
+high-field muz(Hz,D,T) is determined, together with the associated spin-flop
+field HSF(D,T) at which a second-order SF to PM phase transition occurs. The
+free energies of the AFM, SF and PM phases are derived from which Hz-T phase
+diagrams are constructed. For a certain combination of parameters we find a
+topologically distinct phase diagram where a spin-flop bubble occurs at finite
+Hz and T. Also calculated are properties arising from a perpendicular magnetic
+field. In addition to the above results for D > 0, some properties with D < 0
+are determined. In order to compare the properties of the above spin systems
+with those of noninteracting systems with DSz^2 uniaxial anisotropy with either
+sign of D, an Appendix is included in which results for the thermal and
+magnetic properties of such noninteracting spin systems are provided.",1701.05416v1
+2017-01-26,Seed Layer Impact on Structural and Magnetic Properties of [Co/Ni] Multilayers with Perpendicular Magnetic Anisotropy,"[Co/Ni] multilayers with perpendicular magnetic anisotropy (PMA) have been
+researched and applied in various spintronic applications. Typically the seed
+layer material is studied to provide the desired face-centered cubic
+(\textit{fcc}) texture to the [Co/Ni] to obtain PMA. The integration of [Co/Ni]
+in back-end-of-line (BEOL) processes also requires the PMA to survive
+post-annealing. In this paper, the impact of NiCr, Pt, Ru, and Ta seed layers
+on the structural and magnetic properties of [Co(0.3 nm)/Ni(0.6 nm)]
+multilayers is investigated before and after annealing. The multilayers were
+deposited \textit{in-situ} on different seeds via physical vapor deposition at
+room temperature. The as-deposited [Co/Ni] films show the required
+\textit{fcc}(111) texture on all seeds, but PMA is only observed on Pt and Ru.
+In-plane magnetic anisotropy (IMA) is obtained on NiCr and Ta seeds, which is
+attributed to strain-induced PMA loss. PMA is maintained on all seeds after
+post-annealing up to 400$^{\circ}$C. The largest effective perpendicular
+anisotropy energy ($K_U^{\mathrm{eff}}\approx 2\times10^5$J/m$^3$) after
+annealing is achieved on NiCr seed. The evolution of PMA upon annealing cannot
+be explained by further crystallization during annealing or strain-induced PMA,
+nor can the observed magnetization loss and the increased damping after
+annealing. Here we identify the diffusion of the non-magnetic materials from
+the seed into [Co/Ni] as the major driver of the changes in the magnetic
+properties. By selecting the seed and post-annealing temperature, the [Co/Ni]
+can be tuned in a broad range for both PMA and damping.",1701.07713v1
+2017-02-25,Viscosity for Anisotropic Reissner Nordström Blackbranes,"We investigate the behavior of shear viscosity in the presence of small
+anisotropy and a finite chemical potential. First, we construct an anisotropic
+Reissner Nordstr{\""o}m blackbrane in 5 dimensions in a simple Einstein-Maxwell
+theory with a small linear dilaton. This solution is characterized by three
+mass scales : anisotropy $\rho$, temperature T and chemical potential $\mu$. We
+find this solution upto second order in the dilaton anisotropy parameter
+$\rho$. This blackbrane solution corresponds to an anisotropic phase where the
+anisotropy is small compared to the temperature and chemical potential. We find
+that in this anisotropic phase, some components of the anisotropic shear
+viscosity tensor, which are spin one with respect to the residual symmetry
+after breaking rotational invariance, violates the KSS bound (${\eta \over
+s}\ge {1 \over 4 \pi} $) proposed by Kovtun, Son and Starinets. We identify the
+regions of the parameter space where these violations are significant. We carry
+out a similar analysis in 4 dimensions and find similar violation of the KSS
+bound for the spin one components to demonstrate the generality of the result.
+Our results are particularly relevant in the context of strongly coupled
+systems found in nature. We also provide an intuitive understanding of the
+results using dimensional reduction and a Boltzmann calculation in a weakly
+coupled version of a similar system. The Boltzmann analysis performed in a
+system of weakly interacting particles in a linear potential also shows that
+components of the viscosity tensor may be reduced. It is intriguing that the
+Boltzmann analysis also predicts the corrections to be negative and that too in
+a manner similar to the anisotropic strongly coupled theories with smooth
+gravity duals.",1702.07874v4
+2017-04-05,"Structure, site-specific magnetism and magneto-transport properties of epitaxial D0$_{22}$ Mn$_2$Fe$_x$Ga thin films","Ferrimagnetic Mn$_2$Fe$_x$Ga $(0.26 \leq x \leq 1.12)$ thin films have been
+characterised by X-ray diffraction, SQUID magnetometry, X-ray absorption
+spectroscopy, X-ray magnetic circular dichroism and M\""{o}ssbauer spectroscopy
+with the aim of determining the structure and site-specific magnetism of this
+tetragonal, D0$_{22}$-structure Heusler compound. High-quality epitaxial films
+with low RMS surface roughness ($\sim 0.6$ nm) are grown by magnetron
+co-sputtering. The tetragonal distortion induces strong perpendicular magnetic
+anisotropy along the $c$-axis with a typical coercive field $\mu_0 H\sim 0.8$ T
+and an anisotropy field ranging from $6$ to $8$ T. Upon increasing the Fe
+content $x$, substantial uniaxial anisotropy, $K_\mathrm{u} \geq 1.0$ MJ/m$^3$
+can be maintained over the full $x$ range, while the magnetisation of the
+compound is reduced from $400$ to $280$ kA/m. The total magnetisation is almost
+entirely given by the sum of the spin moments originating from the
+ferrimagnetic Mn and Fe sublattices, with the latter being coupled
+ferromagnetically to one of the former. The orbital magnetic moments are
+practically quenched, and have negligible contributions to the magnetisation.
+The films with $x=0.73$ exhibit a high anomalous Hall angle of $2.5$ % and a
+high Fermi-level spin polarisation, above $51$ %, as measured by point contact
+Andreev reflection. The Fe-substituted Mn$_2$Ga films are highly tunable with a
+unique combination of high anisotropy, low magnetisation, appreciable spin
+polarisation and low surface roughness, making them very strong candidates for
+thermally-stable spin-transfer-torque switching nanomagnets with lateral
+dimensions down to $10$ nm.",1704.01326v1
+2017-04-19,Anisotropic magnetic interactions and spin dynamics in the spin-chain compound Cu(py)$_2$Br$_2$: An experimental and theoretical study,"We compare theoretical results for electron spin resonance (ESR) properties
+of the Heisenberg-Ising Hamiltonian with ESR experiments on the
+quasi-one-dimensional magnet Cu(py)$_2$Br$_2$ (CPB). Our measurements were
+performed over a wide frequency and temperature range giving insight into spin
+dynamics, spin structure, and magnetic anisotropy of this compound. By
+analyzing the angular dependence of ESR parameters (resonance shift and
+linewidth) at room temperature we show that the two weakly coupled inequivalent
+spin chain types inside the compound are well described by Heisenberg-Ising
+chains with their magnetic anisotropy axes perpendicular to the chain direction
+and almost perpendicular to each other. We further determine the full
+$g$-tensor from these data. In addition, the angular dependence of the
+linewidth at high temperatures gives us access to the exponent of the algebraic
+decay of a dynamical correlation function of the isotropic Heisenberg chain.
+From the temperature dependence of static susceptibilities we extract the
+strength of the exchange coupling ($J/k_B = 52.0\,\text{K}$) and the anisotropy
+parameter ($\delta\approx -0.02$) of the model Hamiltonian. An independent
+compatible value of $\delta$ is obtained by comparing the exact prediction for
+the resonance shift at low temperatures with high-frequency ESR data recorded
+at $4\,\text{K}$. The spin structure in the ordered state implied by the two
+(almost) perpendicular anisotropy axes is in accordance with the propagation
+vector determined from neutron scattering experiments. In addition to undoped
+samples we study the impact of partial substitution of Br by Cl ions on spin
+dynamics. From the dependence of the ESR linewidth on doping level we infer an
+effective decoupling of the anisotropic component $J\delta$ from the isotropic
+exchange $J$ in these systems.",1704.05705v2
+2017-06-16,Thermodynamic evidence for nematic phase transition at the onset of pseudogap in YBa$_2$Cu$_3$O$_y$,"A central issue in the quest to understand the superconductivity in cuprates
+is the nature and origin of the pseudogap state, which harbours anomalous
+electronic states such as Fermi arc, charge density wave (CDW), and $d$-wave
+superconductivity. A fundamentally important, but long-standing controversial
+problem has been whether the pseudogap state is a distinct thermodynamic phase
+characterized by broken symmetries below the onset temperature $T^*$.
+Electronic nematicity, a fourfold ($C_4$) rotational symmetry breaking, has
+emerged as a key feature inside the pseudogap regime, but the presence or
+absence of a nematic phase transition and its relationship to the pseudogap
+remain unresolved. Here we report thermodynamic measurements of magnetic torque
+in the underdoped regime of orthorhombic YBa$_2$Cu$_3$O$_y$ with a field
+rotating in the CuO$_2$ plane, which allow us to quantify magnetic anisotropy
+with exceptionally high precision. Upon entering the pseudogap regime, the
+in-plane anisotropy of magnetic susceptibility increases after exhibiting a
+distinct kink at $T^*$. Our doping dependence analysis reveals that this
+anisotropy is preserved below $T^*$ even in the limit where the effect of
+orthorhombicity is eliminated. In addition, the excess in-plane anisotropy data
+show a remarkable scaling behaviour with respect to $T/T^*$ in a wide doping
+range. These results provide thermodynamic evidence that the pseudogap onset is
+associated with a second-order nematic phase transition, which is distinct from
+the CDW transition that accompanies translational symmetry breaking. This
+suggests that nematic fluctuations near the pseudogap phase boundary have a
+potential link to the strange metallic behaviour in the normal state, out of
+which high-$T_c$ superconductivity emerges.",1706.05214v1
+2017-06-19,Surface Waves on the Interface Between Hyperbolic Material and Topological Insulator. 1,"Propagation of the surface waves on the interface between an uniaxial
+hyperbolic material and an isotopical topological insulator is studied. The
+cases of the anisotropy axes is normal to interface or one is coplanar to
+interface are discussed. The dispersion relations are derived and analyzed. The
+conditions of the existence of the surface waves are established.",1706.05951v1
+2017-07-06,Distortions of the Cosmic Microwave Background through cooling lines during the epoch of Reionization,"By using N-body hydrodynamical cosmological simulations in which the
+chemistry of major metals and molecules is consistently solved for, we study
+the interaction of metallic fine-structure lines with the CMB. Our analysis
+shows that the collisional induced emissions in the OI 145 $\mu$m and CII 158
+$\mu$m lines during reionization introduce a distortion of the CMB spectrum at
+low frequencies ($\nu < 300$ GHz) with amplitudes up to $\Delta
+I_{\nu}/B_{\nu}(T_{\rm CMB})\sim 10^{-8}$-$10^{-7}$, i.e., at the $\sim 0.1$
+percent level of FIRAS upper limits. Shorter wavelength fine-structure
+transitions (OI 63 $\mu$m, FeII 26 $\mu$m, and SiII 35 $\mu$m) typically sample
+the reionization epoch at higher observing frequencies ($\nu > 400$ GHz). This
+corresponds to the Wien tail of the CMB spectrum and the distortion level
+induced by those lines may be as high as $\Delta I_{\nu}/B_{\nu}(T_{\rm
+CMB})\sim 10^{-4}$. The angular anisotropy produced by these lines should be
+more relevant at higher frequencies: while practically negligible at $\nu=145
+$GHz, signatures from CII 158 $\mu$m and OI 145 $\mu$m should amount to 1%-5%
+of the anisotropy power measured at $l \sim 5000$ and $\nu=220 $GHz by the ACT
+and SPT collaborations (after assuming $\Delta \nu_{\rm obs}/\nu_{\rm
+obs}\simeq 0.005$ for the line observations). Our simulations show that
+anisotropy maps from different lines (e.g., OI 145 $\mu$m and CII 158 $\mu$m)
+at the same redshift show a very high degree ($>0.8$) of spatial correlation,
+allowing for the use of observations at different frequencies to unveil the
+same snapshot of the reionization epoch. Finally, our simulations demonstrate
+that line-emission anisotropies extracted in narrow frequency/redshift shells
+are practically uncorrelated in frequency space, thus enabling standard methods
+for removal of foregrounds that vary smoothly in frequency, just as in HI 21 cm
+studies.",1707.01910v1
+2017-07-25,Reconstruction of the remote dipole and quadrupole fields from the kinetic Sunyaev Zel'dovich and polarized Sunyaev Zel'dovich effects,"The kinetic Sunyaev Zel'dovich (kSZ) and polarized Sunyaev Zel'dovich (pSZ)
+effects are temperature and polarization anisotropies induced by the scattering
+of CMB photons from structure in the post-reionization Universe. In the case of
+the kSZ effect, small angular scale anisotropies in the optical depth are
+modulated by the cosmic microwave background (CMB) dipole field, i.e. the CMB
+dipole observed at each spacetime point, which is sourced by the primordial
+dipole and especially the local peculiar velocity. In the case of the pSZ
+effect, similar small-scale anisotropies are modulated by the CMB quadrupole
+field, which receives contributions from both scalar and tensor modes.
+Statistical anisotropies in the cross correlations of CMB temperature and
+polarization with tracers of the inhomogeneous distribution of electrons
+provide a means of isolating and reconstructing the dipole and quadrupole
+fields. In this paper, we present a set of unbiased minimum variance quadratic
+estimators for the reconstruction of the dipole and quadrupole fields, and
+forecast the ability of future CMB experiments and large scale structure
+surveys to perform this reconstruction. Consistent with previous work, we find
+that a high fidelity reconstruction of the dipole and quadrupole fields over a
+variety of scales is indeed possible, and demonstrate the sensitivity of the
+pSZ effect to primordial tensor modes. Using a principle component analysis, we
+estimate how many independent modes could be accessed in such a reconstruction.
+We also comment on a few first applications of a detection of the dipole and
+quadrupole fields, including a reconstruction of the primordial contribution to
+our locally observed CMB dipole, a test of statistical homogeneity on large
+scales from the first modes of the quadrupole field, and a reconstruction
+technique for the primordial potential on the largest scales.",1707.08129v2
+2017-07-29,Radiation Reaction in a Lorentz-Violating Electrodynamics,"We study radiation reaction in a Lorentz violating electrodynamics [1]. We
+explore the possible modification whatsoever present in the radiation reaction
+force experienced by an accelerating charge in the modified Maxwell theory.
+However it turns out that radiation reaction receives no change due to Lorentz
+violation whereas electromagnetic mass manifests anisotropy.",1707.09522v1
+2017-10-26,Non-London electrodynamics in a multiband London model: anisotropy-induced non-localities and multiple magnetic field penetration lengths,"The London model describes strongly type-2 superconductors as massive vector
+field theories, where the magnetic field decays exponentially at the length
+scale of the London penetration length. This also holds for isotropic
+multi-band extensions, where the presence of multiple bands merely renormalises
+the London penetration length. We show that, by contrast, the magnetic
+properties of anisotropic multi-band London models are not this simple, and the
+anisotropy leads to the inter-band phase differences becoming coupled to the
+magnetic field. This results in the magnetic field in such systems having N+1
+penetration lengths, where N is the number of field components or bands. That
+is, in a given direction, the magnetic field decay is described by N+1 modes
+with different amplitudes and different decay length scales. For certain
+anisotropies we obtain magnetic modes with complex masses. That means that
+magnetic field decay is not described by a monotonic exponential increment set
+by a real penetration length but instead is oscillating. Some of the
+penetration lengths are shown to diverge away from the superconducting phase
+transition when the mass of the phase-difference mode vanishes. Finally the
+anisotropy-driven hybridization of the London mode with the Leggett modes can
+provide an effectively non-local magnetic response in the nominally local
+London model. Focusing on the two-component model, we discuss the magnetic
+field inversion that results from the effective non-locality, both near the
+surface of the superconductor and around vortices. In the regime where the
+magnetic field decay becomes non-monotonic, the multiband London superconductor
+is shown to form weakly-bound states of vortices.",1710.09907v3
+2017-11-30,Inverse Prism based on Temporal Discontinuity and Spatial Dispersion,"We introduce the concept of the inverse prism as the dual of the conventional
+prism and deduce from this duality an implementation of it based on temporal
+discontinuity and spatial dispersion provided by anisotropy. Moreover, we show
+that this inverse prism exhibits the following three unique properties:
+chromatic refraction birefringence, ordinary-monochromatic and extraordinary-
+polychromatic temporal refraction, and linear-to-Lissajous polarization
+transformation.",1711.11204v2
+2018-01-25,Voltage Control of Uni-directional Anisotropy in Ferromagnet-Multiferroic System,"Demonstration of ultra-low energy switching mechanisms is an imperative for
+continued improvements in computing devices. Ferroelectric (FE) and
+multiferroic (MF) orders and their manipulation promises an ideal combination
+of state variables to reach atto-Joule range for logic and memory (i.e., ~ 30X
+lower switching energy than nanoelectronics). In BiFeO3 the coupling between
+the antiferromagnetic (AFM) and FE orders is robust at room temperature,
+scalable in voltage, stabilized by the FE order, and can be integrated into a
+fabrication process for a beyond-CMOS era. The presence of the AFM order and a
+canted magnetic moment in this system causes exchange interaction with a
+ferromagnet such as CoFe or LSMO. While previous work has shown that exchange
+coupling (uniaxial anisotropy) can be controlled with an electric field,
+several puzzling issues remain. Perhaps the most intriguing among them is that
+the BiFeO3-CoFe bilayer did not demonstrate any electrically controlled
+directional anisotropy, i.e., an exchange bias, which is a potential mechanism
+for 180o magnetic reversal and is independent of switching kinetics. However,
+what is needed/preferred for logic and memory is a magneto-electric mechanism
+that works analogous to an applied field, i.e a uni-directional anisotropy that
+is voltage modulated. Here, we present the evidence of electrical control of
+exchange bias of a laterally scaled spin valve that is exchange-coupled to
+BiFeO3 at room temperature. We show that the exchange bias in this bilayer is
+thermally robust, electrically controlled and reversible. We anticipate that
+magneto-electricity at such scaled dimensions provides a powerful pathway for
+computing beyond the modern nanoelectronics transistors by enabling a new class
+of non-volatile, ultra-low energy computing elements.",1801.08280v1
+2018-02-13,Prospects for next generation Cosmic Microwave Background experiments,"In this lecture, after a synthetic review of measurements of CMB temperature
+anisotropies and of their cosmological implications, the theoretical background
+of CMB polarization is summarized and the concepts of the main experiments that
+are ongoing or are being planned are briefly described.",1802.04753v1
+2018-03-16,Generation of Electron Whistler Waves at the Mirror Mode Magnetic Holes: MMS Observations and PIC Simulation,"The Magnetospheric Multiscale (MMS) mission has observed electron whistler
+waves at the center and at the edges of magnetic holes in the dayside
+magnetosheath. The magnetic holes are nonlinear mirror structures since their
+magnitude is anti-correlated with particle density. In this article, we examine
+the growth mechanisms of these whistler waves and their interaction with the
+host magnetic hole. In the observations, as magnetic holes develop and get
+deeper, an electron population gets trapped and develops a temperature
+anisotropy favorable for whistler waves to be generated. In addition, the
+decrease in magnetic field magnitude and the increase in density reduces the
+electron resonance energy, which promotes the electron cyclotron resonance. To
+investigate this process, we used an expanding box particle-in-cell simulations
+to produce the mirror instability, which then evolves into magnetic holes. The
+simulation shows that whistler waves can be generated at the center and edges
+of magnetic holes, which reproduces the primary features of the MMS
+observations. The simulation shows that the electron temperature anisotropy
+develops in the center of the magnetic hole once the mirror instability reaches
+its nonlinear stage of evolution. The plasma is then unstable to whistler waves
+at the minimum of the magnetic field structures. In the saturation regime of
+mirror instability, when magnetic holes are developed, the electron temperature
+anisotropy appears at the edges of the holes and electron distributions become
+more isotropic at the magnetic field minimum. At the edges, the expansion of
+magnetic holes decelerates the electrons which leads to temperature
+anisotropies.",1803.06399v1
+2018-06-11,Spectral Conditions for Equivalence of Gaussian Random Fields with Stationary Increments,"This paper studies the problem of equivalence of Gaussian measures induced by
+Gaussian random fields (GRFs) with stationary increments and proves a
+sufficient condition for the equivalence in terms of the behavior of the
+spectral measures at infinity. The main results extend those of Stein (2004),
+Van Zanten (2007, 2008) and are applicable to a rich family of nonstationary
+space-time models with possible anisotropy behavior.",1806.04181v1
+2018-07-11,Viscous hydrodynamics for nonconformal anisotropic fluids,"A new formulation of (3+1)-dimensional anisotropic hydrodynamics is presented
+that accounts nonperturbatively for the large longitudinal-transverse pressure
+anisotropy and bulk viscous pressure in heavy-ion collisions. The
+initialization of the anisotropic hydrodynamic stage is discussed, and a
+comparison to standard viscous hydrodynamics for (0+1)- dimensional Bjorken
+expansion is presented.",1807.04223v1
+2018-10-04,The Anisotropies and Origins of Ultrahigh Energy Cosmic Rays,"IceCube detects more than 100,000 neutrinos per year in the GeV- to
+PeV-energy range. Among those, we have isolated a flux of high-energy cosmic
+neutrinos. I will discuss the instrument, the analysis of the data, the
+significance of the discovery of cosmic neutrinos, and the recent
+multi-messenger observation of a flaring TeV blazar in coincidence with the
+IceCube neutrino alert IC170922.",1810.02484v1
+2018-11-01,3-omega method for thermal properties of thin film multilayers,"Short review on the different models for the electro-thermal 3-omega method.
+We present the deduction of the fundamental relation between the 3-omega
+voltage with the temperature rise to determine the thermal conductivity. The
+usage of the anisotropy of the films allows a smooth transition between 1D and
+2D models. A comparison between the multilayer methods and analytical solutions
+are presented.",1811.00571v1
+2018-11-20,Results from the Pierre Auger Observatory,"I describe some of the results on ultrahigh-energy cosmic rays that have been
+obtained with the Pierre Auger Observatory. These include measurements of the
+spectrum, composition and anisotropies. Possible astrophysical scenarios that
+account for these results are discussed.",1811.08260v1
+2019-01-01,Comments on the chemical and kinetic equilibration in heavy ion collisions,"I argue that perturbative scattering of quarks and gluons are incompatible
+with lattice and heavy ion data on QGP properties. The non-perturbative
+mechanisms for quasiparticle rescattering and quark production are briefly
+discussed, as well as experiments needed to measure matter anisotropy and quark
+density at early stages of the collisions.",1901.00178v1
+2019-01-02,Magnetization reorientation due to the superconducting transition in heavy-metal heterostructures,"Recent theoretical and experimental work has demonstrated how the
+superconducting critical temperature ($T_c$) can be modified by rotating the
+magnetization of a single homogeneous ferromagnet proximity-coupled to the
+superconducting layer. This occurs when the superconductor and ferromagnet are
+separated by a thin heavy normal metal that provides an enhanced interfacial
+Rashba spin-orbit interaction. We consider the reciprocal effect: magnetization
+reorientation driven by the superconducting phase transition. We solve the
+tight-binding Bogoliubov-de Gennes equations on a lattice self-consistently and
+find that the relative angle between the spin-orbit field and the magnetization
+gives rise to a contribution in the free energy even in the normal state due to
+band-structure effects. For temperatures below $T_c$, superconductivity gives
+rise to a competing contribution. By lowering the temperature, in addition to
+reorientation of the favored magnetization direction from in-plane to
+out-of-plane, a $\pi/4$ in-plane rotation for thicker ferromagnetic layers is
+possible. Furthermore, computation of $T_c$ of the structure in the ballistic
+limit shows a dependence on the in-plane orientation of the magnetization, in
+contrast to our previous result on the diffusive limit. This finding is
+relevant with respect to thin-film heterostructures since these are likely to
+be in the ballistic regime of transport. Finally, we discuss the experimental
+feasibility of observing the magnetic anisotropy induced by the superconducting
+transition when other magnetic anisotropies, such as the shape anisotropy for a
+ferromagnetic film, are taken into account. Our work suggests that the
+superconducting condensation energy in principle can trigger a reorientation of
+the magnetization of a thin-film ferromagnet upon lowering the temperature
+below $T_c$, in particular for ferromagnets with weak magnetic anisotropies.",1901.00501v3
+2019-02-25,Creation Mechanism of Devil's Staircase Surface and Unstable and Stable Periodic Orbit in the Anisotropic Kepler Problem,"A long-standing question in two dimensional Anisotropic Kepler Problem (AKP)
+concerns with the uniqueness of an unstable periodic orbit (PO) for a given
+binary code (modulo symmetry equivalence). In this paper, a finite level ($N$)
+surface defined by the binary coding of the orbit is considered over the
+initial value domain $D_0$. It is proved that a tiling of $D_0$ by base ribbons
+of the surface steps is proper; the surface height increases monotonously when
+ribbons are traversed from left to right. The mechanism of level $N+1$ tiling
+creation from $N$ one is clarified. Two cases are possible depending on the
+code and the anisotropy. (A) Every ribbon shrinks to a line at $N \rightarrow
+\infty$. Here the uniqueness holds. (B) When future (F) and past (P) ribbon
+become tangent each other, they escape from shrinking, Then, the initial values
+of a stable PO ($S$) and an unstable PO ($U$) sharing the same code co-exist
+inside the overlap of F and P non-shrinking ribbons. This case corresponds to
+Broucke's PO. At high anisotropy, it is only case (A), but with decreasing
+anisotropy, bifurcation $U(R) \rightarrow S(R) +U'(NR)$ occurs, along with the
+emergence of a non-shrinking ribbon. (Here $R$ and $NR$ are short for
+self-retracing and non-retracing PO respectively). We conjecture that case (B)
+occurs only for odd rank, $Y$-symmetric POs from a classification based on
+topology and symmetry. We report two applications. First, the classification is
+applied successfully to the successive bifurcation (above bifurcation is
+followed by $S(R) \rightarrow S'(R) +S''(NR)$) of a high-rank PO ($n=15$).
+Second, enhancing sensitivity to co-existence of S and U POs by ribbon tiling,
+we examine high anisotropy region. A new symmetry type PO ($O$ type) is found
+and, at $\gamma =0.2$, all POs are unstable and unique. 13648 POs at rank 10
+verifies that Gutzwiller's action formula amazingly works.",1902.09275v1
+2019-02-25,Modeling Nearly Spherical Pure-Bulge Galaxies with a Stellar Mass-to-Light Ratio Gradient under the $Λ$CDM and MOND Paradigms: II. The Orbital Anisotropy of Slow Rotators within the Effective Radius,"We investigate the anisotropy of the stellar velocity dispersions within the
+effective radius, $R_{\rm e}$, in 24 ATLAS$^{\rm 3D}$ pure-bulge galaxies, 16
+of which are kinematic slow rotators (SRs). We allow the spherical anisotropy
+parameter $\beta$ to be radially varying and allow a radial gradient in the
+stellar mass-to-light ratio ($M_\star/L$) through the parameter $K$ introduced
+earlier. The median anisotropy for SRs depends on $K$ as follows:
+$\langle\beta_{\rm m}\rangle = a + b K$ with $a=0.19\pm 0.05$, $b=-0.13\pm
+0.07$ ($\Lambda$CDM) or $a=0.21\pm 0.05$, $b=-0.26\pm 0.08$ (MOND), where
+$\beta_{\rm m}$ refers to the radially averaged quantity. Under the
+$\Lambda$CDM paradigm this scaling is tied to a scaling of $\langle f_{\rm
+DM}\rangle = (0.16\pm 0.03) +(0.31\pm 0.06) K$, where $f_{\rm DM}$ refers to
+the DM fraction within a sphere of $r=R_{\rm e}$. For $K=0$ (constant
+$M_\star/L$), we obtain radially biased results with $\langle\beta_{\rm
+m}\rangle \approx 0.2$ consistent with previous results. However, marginalizing
+over $0 < K < 1.5$ yields $\langle\beta_{\rm m}\rangle = 0.06 ^{+0.11}_{-0.14}$
+with $\langle f_{\rm DM}\rangle = 0.35 \pm 0.08$: isotropy is preferred. This
+isotropy hides the fact that $\beta_{\rm m}$ is correlated with kinematic
+features such as counter rotating cores (CRCs), kinematically distinct cores
+(KDCs), and low-level velocities (LVs): SRs with LVs are likely to be radially
+biased while SRs with CRCs are likely to be tangentially biased, and SRs with
+KDCs are intermediate. Existing cosmological simulations allow us to understand
+these results qualitatively in terms of their dynamical structures and
+formation histories although there exist quantitative tensions. More realistic
+cosmological simulations, particularly allowing for $M_\star/L$ gradients, may
+be required to better understand SRs.",1902.09350v1
+2019-03-19,Magnetic properties and domain structure of ultrathin yttrium iron garnet/Pt bilayers,"We report on the structure, magnetization, magnetic anisotropy, and domain
+morphology of ultrathin yttrium iron garnet (YIG)/Pt films with thickness
+ranging from 3 to 90 nm. We find that the saturation magnetization is close to
+the bulk value in the thickest films and decreases towards low thickness with a
+strong reduction below 10 nm. We characterize the magnetic anisotropy by
+measuring the transverse spin Hall magnetoresistance as a function of applied
+field. Our results reveal strong easy plane anisotropy fields of the order of
+50-100 mT, which add to the demagnetizing field, as well as weaker in-plane
+uniaxial anisotropy ranging from 10 to 100 $\mu$T. The in-plane easy axis
+direction changes with thickness, but presents also significant fluctuations
+among samples with the same thickness grown on the same substrate. X-ray
+photoelectron emission microscopy reveals the formation of zigzag magnetic
+domains in YIG films thicker than 10 nm, which have dimensions larger than
+several 100 $\mu$m and are separated by achiral N\'{e}el-type domain walls.
+Smaller domains characterized by interspersed elongated features are found in
+YIG films thinner than 10 nm.",1903.08285v1
+2019-05-01,Signals for Lorentz violation in gravitational waves,"Lorentz violations in gravitational waves are investigated. Plane-wave
+solutions for arbitrary gauge-invariant violations in linearized gravity are
+constructed. Signatures of Lorentz violation include dispersion, birefringence,
+and anisotropies. Modifications to waves from coalescing compact binaries and
+to strain signals in gravitational-wave detectors are derived.",1905.00409v1
+2019-05-14,Influence of transverse field on the spin-3/2 Blume-Capel model on rectangular lattice,"Transverse field effect on thermodynamic properties of the spin-3/2
+Blume-Capel model on rectangular lattice in which the interactions in
+perpendicular directions differ in signs is studied within the mean field
+approximation. Phase diagrams in the (transverse field, temperature) plane are
+constructed for various values of single-ion anisotropy.",1905.05852v1
+2019-06-26,Strong electrical magneto-chiral anisotropy in tellurium,"We report the experimental observation of strong electrical magneto-chiral
+anistropy (eMChA) in trigonal tellurium (t-Te) crystals. We introduce the
+tensorial character of the effect and determine several tensor elements and we
+propose a novel intrinsic bandstructure-based mechanism for eMChA which gives a
+reasonable description of the principal results.",1906.10994v1
+2019-07-10,"Quantum Hall Skyrmions at $ν=0,\pm 1$ in monolayer graphene","Monolayer graphene under a strong perpendicular field exhibit quantum Hall
+ferromagnetism with spontaneously broken spin and valley symmetry. The
+approximate SU(4) spin/valley symmetry is broken by small lattice scale effects
+in the central Landau level corresponding to filling factors $\nu=0,\pm 1$.
+Notably the ground state at $\nu=0$ is believed to be a canted
+antiferromagnetic (AF) or a ferromagnetic (F) state depending on the component
+of the magnetic field parallel to the layer and the strength of small
+anisotropies. We study the skyrmions for the filling factors $\nu=\pm 1,0$ by
+using exact diagonalizations on the spherical geometry. If we neglect
+anisotropies we confirm the validity of the standard skyrmion picture
+generalized to four degrees of freedom. For filling factor $\nu=- 1$ the hole
+skyrmion is an infinite-size valley skyrmion with full spin polarization
+because it does not feel the anisotropies. The electron skyrmion is also always
+of infinite size. In the F phase it is always fully polarized while in the AF
+phase it undergoes continuous magnetization under increasing Zeeman energy. In
+the case of $\nu=0$ the skyrmion is always maximally localized in space both in
+F and AF phase. In the F phase it is fully polarized while in the AF it has
+also progressive magnetization with Zeeman energy. The magnetization process is
+unrelated to the spatial profile of the skyrmions contrary to the SU(2) case.
+In all cases the skyrmion physics is dominated by the competition between
+anisotropies and Zeeman effect but not directly by the Coulomb interactions,
+breaking universal scaling with the ratio Zeeman to Coulomb energy.",1907.04612v2
+2019-10-07,Spin Nematic Liquids of the $S=1$ Spin Ladder in Magnetic Field,"The magnetization process of the $S=1$ spin ladder system is investigated
+using the numerical exact diagonalization of finite-size clusters. The
+field-induced spin nematic liquid phase was predicted to appear by our previous
+work. Several ground-state phase diagrams in the plane of the single-ion
+anisotropy and the external magnetic field are obtained in the present study.",1910.02582v1
+2019-11-13,Charged Polytropic Models on Finch-Skea Spacetime,"The static, charged, spherically symmetric matter distribution have been
+studied by considering polytropic equation of state. Two polytropic indices
+have been considered for study. The plots of density, radial pressure,
+tangential pressure, anisotropy and causality condition indicates the models
+are suitable to describe the relativistic polytropes.",1911.05325v1
+2019-12-11,Robust cycloid crossover driven by anisotropy in the skyrmion host GaV$_\mathbf{4}$S$_\mathbf{8}$,"We report on the anomalous magnetization dynamics of the
+cycloidally-modulated spin textures under the influence of uniaxial anisotropy
+in multiferroic $\mathrm{GaV_4S_8}$. The temperature and field dependence of
+the linear ac susceptibility [$\chi_{1\omega}^{\prime}(T,H)$], ac magnetic loss
+[$\chi_{1\omega}^{\prime\prime}(T,H)$], and nonlinear ac magnetic response
+[$M_{3\omega}(T,H)$] are examined across the magnetic phase diagram in the
+frequency range $f = 10-10000$ Hz. According to recent theory, skyrmion
+vortices under axial crystal symmetry are confined along specific orientations,
+resulting in enhanced robustness against oblique magnetic fields and altered
+spin dynamics. We characterize the magnetic response of each spin texture and
+find that the dynamic rigidity of the N\'eel skyrmion lattice appears enhanced
+compared to Bloch-type skyrmions in cubic systems, even in the multidomain
+state. Anomalous $M_{3\omega}$ and strong dissipation emerge over the same
+phase regime where strong variations in the cycloid pitch were observed on
+lowering temperature in recent small-angle neutron scattering experiments
+[White et al., Phys. Rev. B 97, 020401(R) (2018)]. Here, we show that strong
+anisotropy also drives an extended crossover of the zero-field cycloid texture
+in $\mathrm{GaV_4S_8}$. The frequency dependence of these dynamic signatures is
+consistent with that of a robust anharmonic spin texture exhibiting a
+correlated domain arrangement. The results underpin the essential role of
+magnetic anisotropy in enhancing the rigidity of topological spin textures for
+diverse applications.",1912.05367v2
+2020-01-26,"Neutron Induced Fission Fragment Angular Distributions, Anisotropy, and Linear Momentum Transfer Measured with the NIFFTE Fission Time Projection Chamber","The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE)
+collaboration has performed measurements with a fission time projection chamber
+(fissionTPC) to study the fission process by reconstructing full
+three-dimensional tracks of fission fragments and other ionizing radiation. The
+amount of linear momentum imparted to the fissioning nucleus by the incident
+neutron can be inferred by measuring the opening angle between the fission
+fragments. Using this measured linear momentum, fission fragment angular
+distributions can be converted to the center-of-mass frame for anisotropy
+measurements. Angular anisotropy is an important experimental observable for
+understanding the quantum mechanical state of the fissioning nucleus and vital
+to determining detection efficiency for cross section measurements. Neutron
+linear momentum transfer to fissioning $^{235}$U, $^{238}$U, and $^{239}$Pu and
+fission fragment angular anisotropy of $^{235}$U and $^{238}$U as a function of
+neutron energies in the range 130 keV--250 MeV are presented.",2001.09381v1
+2020-03-12,Holographic Entanglement Entropy in Anisotropic Background with Confinement-Deconfinement Phase Transition,"We discuss a general five-dimensional completely anisotropic holographic
+model with three different spatial scale factors, characterized by a Van der
+Waals-like phase transition between small and large black holes. A peculiar
+feature of the model is the relation between anisotropy of the background and
+anisotropy of the colliding heavy ions geometry. We calculate the holographic
+entanglement entropy (HEE) of the slab-shaped region, the orientation of which
+relatively to the beams line and the impact parameter is characterized by the
+Euler angles. We study the dependences of the HEE and its density on the
+thermodynamic (temperature, chemical potential) and geometric (parameters of
+anisotropy, thickness, and orientation of entangled regions) parameters. As a
+particular case the model with two equal transversal scaling factors is
+considered. This model is supported by the dilaton and two Maxwell fields. In
+this case we discuss the HEE and its density in detail: interesting features of
+this model are jumps of the entanglement entropy and its density near the line
+of the small/large black hole phase transition. These jumps depend on the
+anisotropy parameter, chemical potential, and orientation. We also discuss
+different definitions and behavior of c-functions in this model. The c-function
+calculated in the Einstein frame decreases while increasing $\ell$ for all
+$\ell$ in the isotropic case (in regions of $(\mu,T)$-plane far away from the
+line of the phase transition). We find the non-monotonicity of the c-functions
+for several anisotropic configurations, which however does not contradict with
+any of the existing c-theorems since they all base on Lorentz invariance.",2003.05847v2
+2020-04-07,Probing cosmic isotropy with a new X-ray galaxy cluster sample through the $L_{\text{X}}-T$ scaling relation,"The isotropy of the late Universe is an assumption greatly used in astronomy.
+However, many studies have recently reported deviations from isotropy with a
+definitive conclusion yet to be made. New, independent methods to robustly test
+the cosmic isotropy are of crucial importance. In this work, we investigate the
+directional behavior of the X-ray luminosity-temperature ($L_X-T$) relation of
+galaxy clusters. A tight correlation exists between the luminosity and
+temperature of the X-ray-emitting intracluster medium. While the measured
+luminosity depends on the underlying cosmology, the temperature can be
+determined without any cosmological assumptions. By exploiting this property
+one can effectively test the isotropy of cosmological parameters over the full
+extragalactic sky. Here, we used 313 homogeneously selected X-ray galaxy
+clusters from the MCXC catalog and obtained core-excised temperatures for all
+of them. We find that the behavior of the $L_X-T$ relation heavily depends on
+the direction of the sky. Strong anisotropies are detected at a $\sim 4\sigma$
+level toward $(l,b)\sim (280^{\circ}, -20^{\circ})$. Several X-ray and
+cluster-related effects that could potentially explain these anisotropies were
+examined, but none did so. Interestingly, two other available cluster samples
+appear to have a similar behavior throughout the sky, while being fully
+independent of each other and our sample. Performing a joint analysis of the
+three samples, the final anisotropy is further intensified ($\sim 5\sigma$),
+toward $(l,b)\sim (303^{\circ}, -27^{\circ})$, which is in good agreement with
+other cosmological probes. This result demonstrates that X-ray galaxy cluster
+studies that assume perfect isotropy can produce strongly biased results
+whether the underlying reason is cosmological or related to X-rays. The
+identification of the exact nature of these anisotropies is therefore crucial.",2004.03305v1
+2020-04-08,High-order crystal field and rare-earth magnetism in RECo5 intermetallics,"Crystal-field (CF) effects on the rare-earth (RE) ions in ferrimagnetic
+intermetallics NdCo$_5$ and TbCo$_5$ are evaluated using an ab initio density
+functional + dynamical mean-field theory approach in conjunction with a
+quasi-atomic approximation for on-site electronic correlations on the localized
+4$f$ shell. The study reveals an important role of the high-order sectoral
+harmonic component of the CF in the magnetism of RECo$_5$ intermetallics. An
+unexpectedly large value is computed in the both systems for the corresponding
+crystal-field parameter (CFP) $A_6^6 \langle r^6 \rangle$, far beyond what one
+would expect from only electrostatic contributions. It allows solving the
+enigma of the non-saturation of zero-temperature Nd magnetic moments in
+NdCo$_5$ along its easy axis in the Co exchange field. This unsaturated state
+had been previously found out from magnetization distribution probed by
+polarised neutron elastic scattering but had so far remained theoretically
+unexplained. The easy plane magnetic anisotropy of Nd in NdCo$_5$ is strongly
+enhanced by the large value of $A_6^6\langle r^6 \rangle$. Counter-intuitively,
+the polar dependence of anisotropy energy within the easy plane remains rather
+small. The easy plane magnetic anisotropy of Nd is reinforced up to high
+temperatures, which is explained through $J$-mixing effects. The calculated ab
+initio anisotropy constants of NdCo$_5$ and their temperature dependence are in
+quantitative agreement with experiment. Unlike NdCo$_5$, the $A_6^6 \langle r^6
+\rangle$ CFP has negligible effects on the Tb magnetism in TbCo$_5$ suggesting
+that its impact on the RE magnetism is ion-specific across the RECo$_5$ series.
+The origin of its large value is the hybridization of RE and Co states in a
+hexagonally coordinated local environment of the RE ion in RECo$_5$
+intermetallics.",2004.03945v1
+2020-05-11,Quantum dynamics of the corner of the Bianchi IX model in WKB approximation,"In this paper we analyse the Bianchi IX Universe dynamics within the corner
+region associated to the potential term which the spatial curvature induces in
+the Minisuperspace. The study is done in the vacuum and in the presence of a
+massless scalar field $\phi$ and a cosmological constant term $\Lambda$. We
+investigate the dynamics in terms of WKB scenario for which the isotropic
+Misner variables (the volume) and one of the two anisotropic ones (and $\phi$
+when present) are treated on a semi-classical level, while the remaining
+anisotropy degree of freedom, the one trapped in the corner, is described on a
+pure quantum level. The quantum dynamics always reduces to the one of a
+time-dependent Schr\""{o}edinger equation for a harmonic potential with a time
+dependent frequency. The vacuum case is treated in the limits of a collpasing
+and an expanding Universe, while the dynamics in presence of $\phi$ and
+$\Lambda$ is studied for $t \rightarrow \infty $. In both analysis the quantum
+dynamics of the anisotropy variable is associated to a decaying standard
+deviation of its probability density, corresponding to a suppression of the
+quantum anisotropy associated. In the vacuum case, the corner configuration
+becomes an attractor for the dynamics and the evolution resembles that one of a
+Taub cosmology in the limit of a non-singular initial Universe. This suggests
+that if the Bianchi dynamics enters enough the potential corner then the
+initial singularity is removed and a Taub picture emerges. The case when $\phi$
+is present well mimics the De-Sitter phase of an inflationary Universe. Here we
+show that both the classical and quantum anisotropies are exponentially
+suppressed, so that the resulting dynamics corresponds to an isotropic closed
+Robertson-Walker geometry.",2005.05337v2
+2020-06-12,Anisotropy of random motions of gas in Messier 33,"(Abridged) We study the properties of anisotropic and axisymmetric velocity
+ellipsoids from maps of the gas velocity dispersion in nearby galaxies. This
+data allow us to measure the azimuthal-to-radial axis ratio of gas velocity
+ellipsoids, which is a useful tool to study the structure of gaseous orbits in
+the disk. We also present the first estimates of perturbations in gas velocity
+dispersion maps by applying an alternative model that considers isotropic and
+asymmetric random motions. High-quality velocity dispersion maps of the atomic
+medium at various angular resolutions of the nearby spiral galaxy Messier 33,
+are used to test the anisotropic and isotropic velocity models. The velocity
+dispersions of hundreds of individual molecular clouds are also analyzed. The
+HI velocity dispersion of M33 is systematically larger along the minor axis,
+and lower along the major axis. Isotropy is only possible if asymmetric motions
+are considered. Fourier transforms of the HI velocity dispersions reveal a
+bisymmetric mode which is mostly stronger than other asymmetric motions and
+aligned with the minor axis of the galaxy. Within the anisotropic and
+axisymmetric velocity model, the stronger bisymmetry is explained by a radial
+component that is larger than the azimuthal component of the ellipsoid of
+random motions, thus by gaseous orbits that are dominantly radial. The
+azimuthal anisotropy parameter is not strongly dependent on the choice of the
+vertical dispersion. The velocity anisotropy parameter of the molecular clouds
+is observed highly scattered. Perturbations such as HI spiral-like arms could
+be at the origin of the gas velocity anisotropy in M33. Further work is
+necessary to assess whether anisotropic velocity ellispsoids can also be
+invoked to explain the asymmetric gas random motions of other galaxies.",2006.07274v1
+2020-08-31,A gradient Discretisation Method For Anisotropic Reaction Diffusion Models with applications to the dynamics of brain tumours,"A gradient discretisation method (GDM), Gradient schemes, Convergence
+analysis, Existence of weak solutions, Anisotropic reaction diffusion models,
+Dirichlet and Neumann boundary conditions, Non conforming finite element
+methods, Finite volume schemes, Hybrid mixed mimetic (HMM) method,
+Crouzeix--Raviart scheme, Brain tumour dynamics, Fractional anisotropy.",2009.00139v1
+2020-09-07,Unconventional U(1) to $\mathbf{Z_q}$ cross-over in quantum and classical ${\bf q}$-state clock models,"We consider two-dimensional $q$-state quantum clock models with quantum
+fluctuations connecting states with clock transitions with different choices
+for matrix elements. We study the quantum phase transitions in these models
+using quantum Monte Carlo simulations, with the aim of characterizing the
+cross-over from emergent U(1) symmetry at the transition (for $q \ge 4$) to
+$Z_q$ symmetry of the ordered state. We also study classical three-dimensional
+clock models with spatial anisotropy corresponding to the space-time anisotropy
+of the quantum systems. The U(1) to ${Z_q}$ symmetry cross-over in all these
+systems is governed by a dangerously irrelevant operator. We specifically study
+$q=5$ and $q=6$ models with different forms of the quantum fluctuations and
+different anisotropies in the classical models. We find the expected classical
+XY critical exponents and scaling dimensions $y_q$ of the clock fields.
+However, the initial weak violation of the U(1) symmetry in the ordered phase,
+characterized by a $Z_q$ symmetric order parameter $\phi_q$, scales in an
+unexpected way. As a function of the system size $L$, close to the critical
+temperature $\phi_q \propto L^p$, where the known value of the exponent is
+$p=2$ in the classical isotropic clock model. In contrast, for strongly
+anisotropic classical models and the quantum models we find $p=3$. For weakly
+anisotropic classical models we observe a cross-over from $p=2$ to $p=3$
+scaling. The exponent $p$ directly impacts the exponent $\nu'$ governing the
+divergence of the U(1) to $Z_q$ cross-over length scale $\xi'$ in the
+thermodynamic limit, according to the relationship $\nu'=\nu(1+|y_q|/p)$, where
+$\nu$ is the conventional correlation length exponent. We present a
+phenomenological argument based on an anomalous renormalization of the clock
+field in the presence of anisotropy, possibly as a consequence of topological
+(vortex) line defects.",2009.03249v3
+2020-10-05,An estimate for the anisotropic maximum curvature in the planar case,"We fix a Finsler norm $F$ and, using the anisotropic curvature flow, we prove
+that the anisotropic maximum curvature $k^F_{\max}$ of a smooth Jordan curve is
+such that $ k^F_{\max}(\gamma)\geq \sqrt{\kappa/A}$ , where $A$ is the area
+enclosed by $\gamma$ and $\kappa$ the area of the unitary Wulff shape
+associated to the anisotropy $F$.",2010.01871v1
+2020-10-13,Tailoring interface mixing and magnetic properties in (111) Permalloy/Pt multilayers,"We present deposition and characterization of multilayers consisting of 20
+repetitions of 15 $\r{A}$ thick permalloy Ni$_{80}$Fe$_{20}$ at. \% (Py) and 5
+$\r{A}$ Pt. The samples were prepared by two different sputter deposition
+methods, namely dc magnetron sputtering (dcMS) and high power impulse magnetron
+sputtering (HiPIMS), that represent low and moderate ionized flux fraction of
+the film forming material, respectively, for deposition of the Py layers. The
+effect of substrate roughness, working gas pressure and sputter power on the
+in-plane uniaxial magnetic anisotropy of the films are studied. The multilayers
+were characterized by X-ray reflectivity and diffraction, and by
+magneto-optical Kerr effect (MOKE). It is shown that HiPIMS deposition produces
+multilayers with unique surface roughness regardless of the substrate surface
+roughness. Multilayers prepared by both dcMS and HiPIMS deposition present a
+strong (111) texture normal to the film plane. The results show that utilizing
+HiPIMS for deposition of the Py layer leads to a minimum interface mixing
+between individual layers compared to dcMS deposition performed at sputter
+power. This is associated with the smooth surface of Py deposited by HiPIMS.
+However, this sharp interface results in higher coercivity and an opening in
+the hard axis hysteresis loops while multilayers with intermixing present well
+defined in-plane uniaxial anisotropy i.e. a linear hard axis. Comparison with
+Py/Cu and Py/CuPt multilayers, prepared under identical conditions using
+HiPIMS, suggests that poor in-plane uniaxial anisotropy is obtained in the
+Py/Pt case, caused by the inverse magnetostriction arising from the large
+lattice mismatch between Py and Pt. The Py/Pt multilayers that exhibit
+interface mixing have a more relaxed interface and thus presents negligible
+inverse magnetostriction and have better defined anisotropy.",2010.06104v3
+2021-01-19,Phase diagram of the anisotropic triangular lattice Hubbard model,"In a recent study [Phys. Rev. X 10, 021042 (2020)], we showed using
+large-scale density matrix renormalization group (DMRG) simulations on infinite
+cylinders that the triangular lattice Hubbard model has a chiral spin liquid
+phase. In this work, we introduce hopping anisotropy in the model, making one
+of the three distinct bonds on the lattice stronger or weaker compared with the
+other two. We implement the anisotropy in two inequivalent ways, one which
+respects the mirror symmetry of the cylinder and one which breaks this
+symmetry. In the full range of anisotropy, from the square lattice to weakly
+coupled one-dimensional chains, we find a variety of phases. Near the isotropic
+limit we find the three phases identified in our previous work: metal, chiral
+spin liquid, and 120$^\circ$ spiral order; we note that a recent paper suggests
+the apparently metallic phase may actually be a Luther-Emery liquid, which
+would also be in agreement with our results. When one bond is weakened by a
+relatively small amount, the ground state quickly becomes the square lattice
+N\'{e}el order. When one bond is strengthened, the story is much less clear,
+with the phases that we find depending on the orientation of the anisotropy and
+on the cylinder circumference. While our work is to our knowledge the first
+DMRG study of the anisotropic triangular lattice Hubbard model, the overall
+phase diagram we find is broadly consistent with that found previously using
+other methods, such as variational Monte Carlo and dynamical mean field theory.",2101.07454v3
+2021-02-24,Neutrino-Antineutrino Asymmetry From The Space-time Noncommutativity,"A new mechanism having as an origin the space-time noncommutativity has been
+shown to generate anisotropy and axial-like interaction giving rise to a
+leptonic asymmetry for fermionic particles propagating in a curved
+noncommutative $FRW$ universe. As a by-product, for ultra-relativistic
+particles like neutrinos, an analytical expression of this asymmetry is derived
+explicitly. Constraints and bounds from the cosmological parameters are also
+discussed.",2102.12214v1
+2021-03-02,Tunneling in an anisotropic cubic Dirac semi-metal,"Motivated by a recent first principles prediction of an anisotropic cubic
+Dirac semi-metal in a real material Tl(TeMo)$_3$, we study the behavior of
+electrons tunneling through a potential barrier in such systems. To clearly
+investigate effects from different contributions to the Hamiltonian we study
+the model in various limits. First, in the limit of a very thin material where
+the linearly dispersive $z$-direction is frozen out at zero momentum and the
+dispersion in the $x$-$y$ plane is rotationally symmetric. In this limit we
+find a Klein tunneling reminiscent of what is observed in single layer graphene
+and linearly dispersive Dirac semi-metals. Second, an increase in thickness of
+the material leads to the possibility of a non-zero momentum eigenvalue $k_z$
+that acts as an effective mass term in the Hamiltonian. We find that these lead
+to a suppression of Klein tunneling. Third, the inclusion of an anisotropy
+parameter $\lambda\neq 1$ leads to a breaking of rotational invariance.
+Furthermore, we observed that for different values of incident angle $\theta$
+and anisotropy parameter $\lambda$ the Hamiltonian supports different numbers
+of modes propagating to infinity. We display this effect in form of a diagram
+that is similar to a phase diagram of a distant detector. Fourth, we consider
+coexistence of both anisotropy and non-zero $k_z$ but do not find any effect
+that is unique to the interplay between non-zero momentum $k_z$ and anisotropy
+parameter $\lambda$. Last, we studied the case of a barrier that was placed in
+the linearly dispersive direction and found Klein tunneling $T-1\propto
+\theta^6+\mathcal{O}(\theta^8)$ that is enhanced when compared to the Klein
+tunneling in linear Dirac semi-metals or graphene where $T-1\propto
+\theta^2+\mathcal{O}(\theta^4)$.",2103.01807v3
+2021-03-08,"The effects of Vadasz term, anisotropy and rotation on bi-disperse convection","The onset of thermal convection in a uniformly rotating and horizontally
+isotropic bi-disperse porous medium, taking into account the Vadasz term, is
+investigated. Via linear instability analysis, it has been proven that the
+Vadasz term allows the onset of convection via an oscillatory state but does
+not affect convection via a stationary motion.",2103.04939v1
+2021-03-11,Shock Waves in Relativistic Anisotropic Hydrodynamics,"Shock wave solutions in anisotropic relativistic hydrodynamics are
+considered. A new phenomenon of anisotropy-related angular deflection of the
+incident flow by the shock wave front is described. Patterns of velocity and
+momentum transformation by the shock wave front are described.",2103.06745v2
+2021-03-25,Cosmological implications of the anisotropy of ten galaxy cluster scaling relations,"The hypothesis that the late Universe is isotropic and homogeneous is adopted
+by most cosmological studies. The expansion rate $H_0$ is thought to be
+spatially constant, while bulk flows are often presumed to be negligible
+compared to the Hubble expansion, even at local scales. Their effects on the
+redshift-distance conversion are hence usually ignored. Any deviation from this
+consensus can strongly bias the results of such studies and thus the importance
+of testing these assumptions cannot be understated. Scaling relations of galaxy
+clusters can be effectively used for that. In previous works, we observed
+strong anisotropies in cluster scaling relations, whose origins remain
+ambiguous. By measuring many different cluster properties, several scaling
+relations with different sensitivities can be built. Nearly independent tests
+of cosmic isotropy and bulk flows are then feasible. We make use of up to 570
+clusters with measured properties at X-ray, microwave, and infrared
+wavelengths, to construct 10 different cluster scaling relations (five of them
+presented for the first time) and test the isotropy of the local Universe.
+Through rigorous tests, we ensure that our analysis is not prone to generally
+known systematic biases and X-ray absorption issues. By combining all available
+information, we detect an apparent $9\%$ spatial variation in the local $H_0$
+between $(l,b)\sim
+({280^{\circ}}^{+35^{\circ}}_{-35^{\circ}},{-15^{\circ}}^{+20^{\circ}}_{-20^{\circ}})$
+and the rest of the sky. The observed anisotropy has a nearly dipole form.
+Using Monte Carlo simulations, we assess the statistical significance of the
+anisotropy to be $>5\sigma$. This result could also be attributed to a $\sim
+900$ km/s bulk flow which seems to extend out to at least $\sim 500$ Mpc. These
+two effects are indistinguishable until more high$-z$ clusters are observed by
+future all-sky surveys, such as eROSITA.",2103.13904v1
+2021-05-04,Resampling Methods for Detecting Anisotropic Correlation Structure,"This paper proposes parametric and non-parametric hypothesis testing
+algorithms for detecting anisotropy -- rotational variance of the covariance
+function in random fields. Both algorithms are based on resampling mechanisms,
+which enable avoiding relying on asymptotic assumptions, as is common in
+previous algorithms. The algorithms' performance is illustrated numerically in
+simulation experiments and on real datasets representing a variety of potential
+challenges.",2105.01654v2
+2021-05-19,Dynamical analysis of clusters of galaxies from cosmological simulations,"Studies of cluster mass and velocity anisotropy profiles are useful tests of
+dark matter models, and of the assembly history of clusters of galaxies. These
+studies might be affected by unknown systematics caused by projection effects.
+We aim at testing observational methods for the determination of mass and
+velocity anisotropy profiles of clusters of galaxies. Particularly, we focus on
+the MAMPOSSt technique (Mamon et al. 2013).
+  We use results from two semi-analytic models of galaxy formation coupled with
+high-resolution N-body cosmological simulations, the catalog of De Lucia &
+Blaizot (2007) and the FIRE catalog based on the new GAlaxy Evolution and
+Assembly model.
+  We test the reliability of the Jeans equation in recovering the true mass
+profile when full projected phase-space information is available. We examine
+the reliability of the MAMPOSSt method in estimating the true mass and velocity
+anisotropy profiles of the simulated halos when only projected phase-space
+information is available, as in observations.
+  The spherical Jeans equation provides a reliable tool for the determination
+of cluster mass profiles, also for subsamples of tracers separated by galaxy
+color. Results are equally good for prolate and oblate clusters. Using only
+projected phase-space information, MAMPOSSt provides estimates of the mass
+profile with a standard deviation of 35-69 %, and a negative bias of 7-17 %,
+nearly independent of radius, and that we attribute to the presence of
+interlopers in the projected samples. The bias changes sign, that is, the mass
+is over-estimated, for prolate clusters with their major axis aligned along the
+line-of-sight. MAMPOSSt measures the velocity anisotropy profiles accurately in
+the inner cluster regions, with a slight overestimate in the outer regions,
+both for the whole sample of observationally-identified cluster members and
+separately for red and blue galaxies.",2105.09126v1
+2021-07-26,Graphical translators for anisotropic and crystalline mean curvature flow,"In this paper we discuss existence, uniqueness and some properties of a class
+of solitons to the anisotropic mean curvature flow, i.e., graphical
+translators, either in the plane or under an assumption of cylindrical symmetry
+on the anisotropy and the mobility. In these cases, the equation becomes an
+ordinary differential equation, and this allows to find explicitly the
+translators and describe their main features.",2107.12082v1
+2021-08-12,Optical anisotropies of asymmetric double GaAs (001) Quantum Wells,"In the present work, we were able to identify and characterize a new source
+of in-plane optical anisotropies (IOAs) occurring in asymmetric DQWs; namely a
+reduction of the symmetry from $D_{2d}$ to $C_{2v}$ as imposed by asymmetry
+along the growth direction. We report on reflectance anisotropy spectroscopy
+(RAS) of double GaAs quantum wells (DQWs) structures coupled by a thin ($<2$
+nm) tunneling barrier. Two groups of DQWs systems were studied: one where both
+QWs have the same thickness (symmetric DQW) and another one where they have
+different thicknesses (asymmetric DQW). RAS measures the IOAs arising from the
+intermixing of the heavy- and light- holes in the valence band when the
+symmetry of the DQW system is lowered from $D_{2d}$ to $C_{2v}$. If the DQW is
+symmetric, residual IOAs stem from the asymmetry of the QW interfaces; for
+instance, associated to Ga segregation into the AlGaAs layer during the
+epitaxial growth process. In the case of an asymmetric DQW with QWs with
+different thicknesses, the AlGaAs layers (that are sources of anisotropies) are
+not distributed symmetrically at both sides of the tunneling barrier. Thus, the
+system losses its inversion symmetry yielding an increase of the RAS strength.
+The RAS line shapes were compared with reflectance spectra in order to assess
+the heavy- and light- hole mixing induced by the symmetry breakdown. The
+energies of the optical transitions were calculated by numerically solving the
+one-dimensional Schr\""odinger equation using a finite-differences method. Our
+results are useful for interpretation of the transitions occurring in both,
+symmetric and asymmetric DQWs.",2108.05920v1
+2021-08-26,Elastic and electro-optical properties of flexible fluorinated dimers with negative dielectric anisotropy,"We report the synthesis and the temperature dependencies of optical,
+dielectric, and elastic properties of four homologous dimeric mesogens in the
+uniaxial nematic (N) phase.",2108.11855v1
+2021-12-11,Various Applications of Transition Metal Dichalcogenides,"TMDs have recently been spotlighted due to their original features. Firstly,
+they have layered structures with Van der Waals interactions. Secondly, they
+have different phases, affecting a degree of anisotropy. Finally, they have
+excellent carrier mobilities. In this review, based on these characteristics,
+this journal shows how TMDs can be applied in a wide variety of industries. The
+main applications that will be treated is biomedical and electronic
+applications.",2112.05919v1
+2022-01-21,Probing Anisotropies of the Stochastic Gravitational Wave Background with LISA,"We investigate the sensitivity of the Laser Interferometer Space Antenna
+(LISA) to the anisotropies of the Stochastic Gravitational Wave Background
+(SGWB). We first discuss the main astrophysical and cosmological sources of
+SGWB which are characterized by anisotropies in the GW energy density, and we
+build a Signal-to-Noise estimator to quantify the sensitivity of LISA to
+different multipoles. We then perform a Fisher matrix analysis of the prospects
+of detectability of anisotropic features with LISA for individual multipoles,
+focusing on a SGWB with a power-law frequency profile. We compute the noise
+angular spectrum taking into account the specific scan strategy of the LISA
+detector. We analyze the case of the kinematic dipole and quadrupole generated
+by Doppler boosting an isotropic SGWB. We find that $\beta\, \Omega_{\rm
+GW}\sim 2\times 10^{-11}$ is required to observe a dipolar signal with LISA.
+The detector response to the quadrupole has a factor $\sim 10^3 \,\beta$
+relative to that of the dipole. The characterization of the anisotropies, both
+from a theoretical perspective and from a map-making point of view, allows us
+to extract information that can be used to understand the origin of the SGWB,
+and to discriminate among distinct superimposed SGWB sources.",2201.08782v1
+2022-02-15,On the robustness of the velocity anisotropy parameter in probing the stellar kinematics in Milky Way like galaxies: Take away from TNG50 simulation,"We analyze the velocity anisotropy of stars in real and energy space for a
+sample of Milky Way-like galaxies in the TNG50 simulation. We employ different
+selection criteria, including spatial, kinematic and metallicity cuts, and make
+three halo classes ($\mathcal{A}$-$\mathcal{C}$) which show mild-to-strong
+sensitivity to different selections. The above classes cover 48%, 16% and 36%
+of halos, respectively. We analyze the $\beta$ radial profiles and divide them
+into either monotonically increasing radial profiles or ones with peaks and
+troughs. We demonstrate that halos with monotonically increasing $\beta$
+profiles are mostly from class $\mathcal{A}$, whilst those with peaks/troughs
+are part of classes $\mathcal{B}$-$\mathcal{C}$. This means that care must be
+taken as the observationally reported peaks/troughs might be a consequence of
+different selection criteria. We infer the anisotropy parameter $\beta$ energy
+space and compare that against the $\beta$ radial profile. It is seen that 65%
+of halos with very mild sensitivity to different selections in real space, are
+those for which the $\beta$ radial and energy profiles are closely related.
+Consequently, we propose that comparing the $\beta$ radial and energy profiles
+might be a novel way to examine the sensitivity to different selection criteria
+and thus examining the robustness of the anisotropy parameter in tracing
+stellar kinematics. We compare simulated $\beta$ radial profiles against
+various observations and demonstrate that, in most cases, the model diversity
+is comparable with the error bars from different observations, meaning that the
+TNG50 models are in good overall agreement with observations.",2202.07162v3
+2022-03-28,Holographic $\mathrm{QCD}_{3}$ and Chern-Simons theory from anisotropic supergravity,"Based on the gauge-gravity duality, we study the three-dimensional QCD
+($\mathrm{QCD}_{3}$) and Chern-Simons theory by constructing the anisotropic
+black D3-brane solution in IIB supergravity. The deformed bulk geometry is
+obtained by performing a double Wick rotation and dimension reduction which
+becomes an anisotropic bubble configuration exhibiting confinement in the dual
+theory. And its anisotropy also reduces to a Chern-Simons term due to the
+presence of the dissolved D7-branes or the axion field in bulk. Using the
+bubble geometry, we investigate the the ground-state energy density, quark
+potential, entanglement entropy and the baryon vertex according to the standard
+methods in the AdS/CFT dictionary. Our calculation shows that the ground-state
+energy illustrates degenerate to the Chern-Simons coupling coefficient which is
+in agreement with the properties of the gauge Chern-Simons theory. The behavior
+of the quark tension, entanglement entropy and the embedding of the baryon
+vertex further implies strong anisotropy may destroy the confinement.
+Afterwards, we additionally introduce various D7-branes as flavor and
+Chern-Simons branes to include the fundamental matter and effective
+Chern-Simons level in the dual theory. By counting their orientation, we
+finally obtain the associated topological phase in the dual theory and the
+critical mass for the phase transition. Interestingly the formula of the
+critical mass reveals the flavor symmetry, which may relate to the chiral
+symmetry, would be restored if the anisotropy increases greatly. As all of the
+analysis is consistent with characteristics of quark-gluon plasma, we therefore
+believe our framework provides a remarkable way to understand the features of
+Chern-Simons theory, the strong coupled nuclear matter and its deconfinement
+condition with anisotropy.",2203.14489v3
+2022-04-05,"Angle-resolved polarized Raman spectroscopy for distinguishing stage-I graphite intercalation compounds with Thorium, Uranium and Plutonium","Graphite intercalation compounds (GICs) with the geometrical anisotropy and
+strong electron-phonon coupling are in full swing and have shown their great
+potential for applications in nanodevices. I selected representative three
+elements in actinide group with valence electron arrangement: Thorium (Th)
+([Rn]6d27s2), Uranium (U) ([Rn]5f36d17s2), Plutonium (Pu) ([Rn]5f67s2). I
+calculated their phonon spectra and demonstrated the atomic-scale
+microstructure identification of actinide graphite intercalation compounds by
+angle-resolved polarized Raman spectroscopy.",2204.01967v1
+2022-05-31,Non-Gaussianity constraints from Planck spectral distortion cross-correlations,"Primordial non-Gaussianity can source $\mu$-distortion anisotropies that are
+correlated with the large-scale temperature and polarization signals of the
+cosmic microwave background (CMB). A measurement of $\mu T$ and $\mu E$
+correlations can therefore be used to constrain it on wavelengths of
+perturbations not directly probed by the standard CMB anisotropies. In this
+work, we carry out a first rigorous search for $\mu$-type spectral distortion
+anisotropies with \Planck data, applying the well-tested constrained ILC
+component-separation method combined with the needlet framework. We reconstruct
+a $\mu$ map from \Planck data, which we then correlate with the CMB
+anisotropies to derive constraints on the amplitude $\fNL$ of the local form
+bispectrum, specifically on the highly squeezed configurations with effective
+wavenumbers $k_s \simeq \SI{740}{Mpc^{-1}}$ and $k_L \simeq
+\SI{0.05}{Mpc^{-1}}$. We improve previously estimated constraints by more than
+an order of magnitude. This enhancement is owing to the fact that for the first
+time we are able to use the full multipole information by carefully controlling
+biases and systematic effects in the final analysis. We also for the first time
+incorporate constraints from measurements of $\mu E$ correlations, which
+further tighten the limits. A combination of the derived \Planck $\mu T$ and
+$\mu E$ power spectra yields $|\fNL| \lesssim 6800$ (95\% c.l.) on this highly
+squeezed bispectrum. This is only $\simeq 3$ times weaker than the anticipated
+constraint from \LiteBIRD alone. We show that a combination of \LiteBIRD with
+\Planck will improve the expected future constraint by $\simeq 20\%$ over
+\LiteBIRD alone. These limits can be used to constrain multi-field inflation
+models and primordial black hole formation scenarios, thus providing a
+promising novel avenue forward in CMB cosmology.",2205.15971v1
+2022-06-21,Electron-driven instabilities in the solar wind,"The electrons are an essential particle species in the solar wind. They often
+exhibit non-equilibrium features in their velocity distribution function. These
+include temperature anisotropies, tails (kurtosis), and reflectional
+asymmetries (skewness), which contribute a significant heat flux to the solar
+wind. If these non-equilibrium features are sufficiently strong, they drive
+kinetic micro-instabilities. We develop a semi-graphical framework based on the
+equations of quasi-linear theory to describe electron-driven instabilities in
+the solar wind. We apply our framework to resonant instabilities driven by
+temperature anisotropies. These include the electron whistler anisotropy
+instability and the propagating electron firehose instability. We then describe
+resonant instabilities driven by reflectional asymmetries in the electron
+distribution function. These include the electron/ion-acoustic, kinetic
+Alfv\'en heat-flux, Langmuir, electron-beam, electron/ion-cyclotron,
+electron/electron-acoustic, whistler heat-flux, oblique
+fast-magnetosonic/whistler, lower-hybrid fan, and electron-deficit whistler
+instability. We briefly comment on non-resonant instabilities driven by
+electron temperature anisotropies such as the mirror-mode and the
+non-propagating firehose instability. We conclude our review with a list of
+open research topics in the field of electron-driven instabilities in the solar
+wind.",2206.10403v1
+2022-08-04,Boltzmann equations for astrophysical Stochastic Gravitational Wave Backgrounds scattering off of massive objects,"This work presents a set of coupled Boltzmann equations describing the
+intensity and polarisation Stokes parameters of the SGWB. Collision terms,
+which account for gravitational Compton scattering off of massive objects, are
+also included. This set resembles that for the CMB Stokes parameters, but the
+different spin nature of the gravitational radiation and the physics involved
+in the scattering process determine crucial differences. In this case, due to
+the Rutherford angular dependence of the cross section, all the SGWB intensity
+multipoles of order $\ell$ are scattered out, producing outgoing intensity
+anisotropies of any order $\ell$ if they are present in the incoming radiation.
+On the other hand, SGWB linear polarisation modes can be expanded in a basis of
+spherical harmonics with $m=\pm 4$ and $\ell\ge 4$. This means that SGWB
+polarisation modes can be generated from unpolarised anisotropic radiation only
+with $m=\pm 4$, therefore requiring at least a hexadecapole anisotropy
+($\ell\ge 4$) in the incoming intensity. Assuming a simplified toy model, we
+solve analytically the set of coupled Boltzmann equations to get explicit
+expressions for the intensity and polarisation angular power spectra. We
+confirm the contribution of the gravitational Compton scattering to the SGWB
+anisoptropies is extremely small for collisions with compact objects in the
+frequency range of current and upcoming surveys. The system of coupled
+Boltzmann equations presented here provides a way to an accurate estimate of
+the total amount of anisotropies generated by multiple SGWB scattering
+processes off of massive objects, as well as the interplay between polarisation
+and intensity, during the GW propagation across the LSS of the universe. These
+results will be useful for the full treatment of the astrophysical SWGB
+anisotropies in view of upcoming gravitational waves observatories.",2208.02800v3
+2022-08-30,Reynolds Stress Anisotropy Tensor Predictions for Turbulent Channel Flow using Neural Networks,"The Reynolds-Averaged Navier-Stokes (RANS) approach remains a backbone for
+turbulence modeling due to its high cost-effectiveness. Its accuracy is largely
+based on a reliable Reynolds stress anisotropy tensor closure model. There has
+been an amount of work aiming at improving traditional closure models, while
+they are still not satisfactory to some complex flow configurations. In recent
+years, advances in computing power have opened up a new way to address this
+problem: the machine-learning-assisted turbulence modeling. In this paper, we
+employ neural networks to fully predict the Reynolds stress anisotropy tensor
+of turbulent channel flows at different friction Reynolds numbers, for both
+interpolation and extrapolation scenarios. Several generic neural networks of
+Multi-Layer Perceptron (MLP) type are trained with different input feature
+combinations to acquire a complete grasp of the role of each parameter. The
+best performance is yielded by the model with the dimensionless mean streamwise
+velocity gradient $\alpha$, the dimensionless wall distance $y^+$ and the
+friction Reynolds number $\mathrm{Re}_\tau$ as inputs. A deeper theoretical
+insight into the Tensor Basis Neural Network (TBNN) clarifies some remaining
+ambiguities found in the literature concerning its application of Pope's
+general eddy viscosity model. We emphasize the sensitivity of the TBNN on the
+constant tensor $\textbf{T}^{*(0)}$ upon the turbulent channel flow data set,
+and newly propose a generalized $\textbf{T}^{*(0)}$, which considerably
+enhances its performance. Through comparison between the MLP and the augmented
+TBNN model with both $\{\alpha, y^+, \mathrm{Re}_\tau\}$ as input set, it is
+concluded that the former outperforms the latter and provides excellent
+interpolation and extrapolation predictions of the Reynolds stress anisotropy
+tensor in the specific case of turbulent channel flow.",2208.14301v1
+2022-09-13,"Large amplitude bidirectional anisotropy of cosmic-ray intensity observed with world-wide networks of ground-based neutron monitors and muon detectors in November, 2021","We analyze the cosmic-ray variations during a significant Forbush decrease
+observed with world-wide networks of ground-based neutron monitors and muon
+detectors during November 3-5, 2021. Utilizing the difference between primary
+cosmic-ray rigidities monitored by neutron monitors and muon detectors, we
+deduce the rigidity spectra of the cosmic-ray density (or omnidirectional
+intensity) and the first- and second-order anisotropies separately, for each
+hour of data. A clear two-step decrease is seen in the cosmic-ray density with
+the first $\sim2\%$ decrease after the interplanetary shock arrival followed by
+the second $\sim5\%$ decrease inside the magnetic flux rope (MFR) at 15 GV.
+Most strikingly, a large bidirectional streaming along the magnetic field is
+observed in the MFR with a peak amplitude of $\sim5\%$ at 15 GV which is
+comparable to the total density decrease inside the MFR. The bidirectional
+streaming could be explained by adiabatic deceleration and/or focusing in the
+expanding MFR, which have stronger effects for pitch angles near 90$^\circ$, or
+by selective entry of GCRs along a leg of the MFR. The peak anisotropy and
+density depression in the flux rope both decrease with increasing rigidity. The
+spectra vary dynamically indicating that the temporal variations of density and
+anisotropy appear different in neutron monitor and muon detector data.",2209.05743v1
+2022-10-25,Cosmic ray anisotropy study by means of detection of muon bundles,"In this work, we use muon bundles which are formed in extensive air showers
+and detected at the ground level as a tool for searching anisotropy of high
+energy cosmic rays. Such choice is explained by the penetrating ability of
+muons which allows them to retain the direction of primary particles with a
+good accuracy. In 2012-2022, we performed long-term muon bundle detection with
+the coordinate-tracking detector DECOR, which is a part of the Experimental
+complex NEVOD (MEPhI, Moscow). To search for the cosmic rays anisotropy, the
+muon bundles arriving at zenith angles in the range from 15 to 75 degrees in
+the local coordinate system are used. During the entire period of data taking,
+about 14 million of such events have been accumulated. In this paper, we
+describe some methods developed in the Experimental complex NEVOD and
+implemented in our research, including: the method for compensating the
+influence of meteorological conditions on the intensity of muon bundles at the
+Earth's surface, the method for accounting the design features of the detector
+and the inhomogeneity of the detection efficiency for different directions, as
+well as the method for estimating primary energies of cosmic rays. Here we
+present the results of the search for the dipole anisotropy of cosmic rays with
+energies in the PeV region and also compare them with the results obtained at
+the other scientific facilities.",2210.13916v1
+2022-10-27,Modelling shock-like injections of solar energetic particles with 3D test particle simulations,"Solar Energetic Particle (SEP) acceleration and injection into interplanetary
+space during gradual SEP events is thought to take place at Coronal Mass
+Ejection (CME)-driven shocks. Features of measured intensity profiles at 1 au
+have been attributed to properties of the radial and longitudinal/latitudinal
+injections at the shock. Focussed transport models are typically used to model
+acceleration at a CME-shock and subsequent propagation. Test particle
+simulations are an alternative approach but so far they have been carried out
+only with instantaneous injection near the Sun. We develop the first temporally
+extended shock-like injection for our 3D test particle code and investigate how
+the spatial features of injection affect SEP intensity and anisotropy profiles
+for observers at 0.3 and 1.0 au. We conduct simulations of a monoenergetic
+population of 5 MeV protons considering three different radial injection
+functions and two longitudinal/latitudinal injection functions. We consider a
+range of scattering conditions with scattering mean free path values ranging
+from 0.1-1.0 au, and determine intensity and anisotropy profiles at six
+observers at different longitudinal locations. We find that the radial,
+longitudinal and latitudinal injection functions play a relatively minor role
+in shaping the SEP intensity profiles. The dependence of profiles on the value
+of the scattering mean free path is also weak, unlike what is found from 1D
+focussed transport models. Spatial factors, such as the time of
+observer-shock-connection/disconnection and time of shock passage have a much
+stronger influence on SEP intensities and anisotropies. Persistent anisotropies
+until shock passage are seen in our simulations. Comparing instantaneous and
+shock-like injections, we find that the link between duration of injection and
+of the SEP event is very weak, unlike what is commonly assumed.",2210.15587v2
+2022-11-30,Vortex-bound solitons in topological superfluid $^3$He,"The different superfluid phases of $^3$He are described by $p$-wave order
+parameters that include anisotropy axes both in the orbital and spin spaces.
+The anisotropy axes characterize the broken symmetries in these macroscopically
+coherent quantum many-body systems. The systems' free energy has several
+degenerate minima for certain orientations of the anisotropy axes. As a result,
+spatial variation of the order parameter between two such regions, settled in
+different energy minima, forms a topological soliton. Such solitons can
+terminate in the bulk liquid, where the termination line forms a vortex with
+trapped circulation of mass and spin superfluid currents. Here we discuss
+possible soliton-vortex structures based on the symmetry and topology arguments
+and focus on the three structures observed in experiments: solitons bounded by
+spin-mass vortices in the B phase, solitons bounded by half-quantum vortices in
+the polar and polar-distorted A phases, and the composite defect formed by a
+half-quantum vortex, soliton and the Kibble-Lazarides-Shafi wall in the
+polar-distorted B phase. The observations are based on nuclear magnetic
+resonance (NMR) techniques and are of three types: first, solitons can form a
+potential well for trapped spin waves, observed as an extra peak in the NMR
+spectrum at shifted frequency; second, they can increase the relaxation rate of
+the NMR spin precession; lastly, the soliton can present the boundary
+conditions for the anisotropy axes in bulk, modifying the bulk NMR signal.
+Owing to solitons' prominent NMR signatures and the ability to manipulate their
+structure with external magnetic field, solitons have become an important tool
+for probing and controlling the structure and dynamics of superfluid $^3$He, in
+particular half-quantum vortices with core-bound Majorana modes.",2211.17117v2
+2022-12-19,"Quantum Magnetic Properties, Entanglement for Antiferromagnetic Spin 1 and 3/2 Cluster Models","Entanglement, magnetization and magnetic susceptibility for 1D
+antiferromagnetic spin 1 and spin 3/2 Heisenberg XXX model with
+Dzyaloshinskii-Moriya interaction, single-ion anisotropy and external magnetic
+field on the finite chain are obtained.",2212.09403v2
+2022-12-27,Potential signature of a quadrupolar Hubble expansion in Pantheon+ supernovae,"The assumption of isotropy -- that the Universe looks the same in all
+directions on large scales -- is fundamental to the standard cosmological
+model. This model forms the building blocks of essentially all of our
+cosmological knowledge to date. It is therefore critical to empirically test in
+which regimes its core assumptions hold. Anisotropies in the cosmic expansion
+are expected on small scales due to nonlinear structures in the late Universe,
+however, the extent to which these anisotropies might impact our low-redshift
+observations remains to be fully tested. In this paper, we use fully general
+relativistic simulations to calculate the expected local anisotropic expansion
+and identify the dominant multipoles in cosmological parameters to be the
+quadrupole in the Hubble parameter and the dipole in the deceleration
+parameter. We constrain these multipoles simultaneously in the new Pantheon+
+supernova compilation. The fiducial analysis is done in the rest frame of the
+CMB with peculiar velocity corrections. Under the fiducial range of redshifts
+in the Hubble flow sample, we find a $\sim 2\sigma$ deviation from isotropy. We
+constrain the eigenvalues of the quadrupole in the Hubble parameter to be
+$\lambda_1 =0.021\pm{ 0.011}$ and $ {\lambda_2= 3.15\times 10^{-5}}\pm 0.012$
+and place a $1\sigma$ upper limit on its amplitude of $2.88\%$. We find no
+significant dipole in the deceleration parameter, finding constraints of
+$q_{\rm dip} = 4.5^{+1.9}_{-5.4}$. However, in the rest frame of the CMB
+without corrections, we find $ q_{ \rm dip} = 9.6^{+4.0}_{-6.9}$, a $>2\sigma$
+positive amplitude. We also investigate the impact of these anisotropies on the
+Hubble tension. We find a maximal shift of $0.30$ km s$^{-1}$ Mpc$^{-1}$ in the
+monopole of the Hubble parameter and conclude that local anisotropies are
+unlikely to fully explain the observed tension.",2212.13569v1
+2023-01-10,On the evolution of the Anisotropic Scaling of Magnetohydrodynamic Turbulence in the Inner Heliosphere,"We analyze a merged Parker Solar Probe ($PSP$) and Solar Orbiter ($SO$)
+dataset covering heliocentric distances $13 \ R_{\odot} \lesssim R \lesssim
+220$ $R_{\odot}$ to investigate the radial evolution of power and
+spectral-index anisotropy in the wavevector space of solar wind turbulence. Our
+results show that anisotropic signatures of turbulence display a distinct
+radial evolution when fast, $V_{sw} \geq ~ 400 ~km ~s^{-1}$, and slow, $V_{sw}
+\leq ~ 400 ~km ~s^{-1}$, wind streams are considered. The anisotropic
+properties of slow wind in Earth orbit are consistent with a ``critically
+balanced'' cascade, but both spectral-index anisotropy and power anisotropy
+diminish with decreasing heliographic distance. Fast streams are observed to
+roughly retain their near-Sun anisotropic properties, with the observed
+spectral index and power anisotropies being more consistent with a
+``dynamically aligned'' type of cascade, though the lack of extended fast-wind
+intervals makes it difficult to accurately measure the anisotropic scaling. A
+high-resolution analysis during the first perihelion of PSP confirms the
+presence of two sub-ranges within the inertial range, which may be associated
+with the transition from weak to strong turbulence. The transition occurs at
+$\kappa d_{i} \approx 6 \times 10^{-2}$, and signifies a shift from -5/3 to -2
+and -3/2 to -1.57 scaling in parallel and perpendicular spectra, respectively.
+Our results provide strong observational constraints for anisotropic theories
+of MHD turbulence in the solar wind.",2301.03896v4
+2022-12-09,Anisotropy of Cosmic Rays and Chaotic Trajectories in the Heliosphere,"As cosmic rays (CRs) propagate in the Galaxy, they can be affected by
+magnetic structures that temporarily trap them and cause their trajectories to
+display chaotic behavior, therefore modifying the simple diffusion scenario.
+When CRs arrive at the Earth, they do so anisotropically. These chaotic effects
+can be a fundamental contributor to this anisotropy. Accordingly, this requires
+a comprehensive description of chaos in trapping conditions since assessing
+their repercussions on the CR arrival directions is necessary. This study
+utilizes a new method described in L\'opez-Barquero and Desiati (2021) to
+characterize chaotic trajectories in bound systems. This method is based on the
+Finite-Time Lyapunov Exponent (FTLE), a quantity that determines the levels of
+chaos based on the trajectories' divergence rate. The FTLE is useful since it
+adapts to trapping conditions in magnetic structures or even propagating media
+changes. Here, we explore the effects that chaos and trapping can have on the
+TeV CR anisotropy. Concretely, we apply this method to study the behavior of
+CRs entering the heliosphere. Specifically, how the distinct heliospheric
+structures and CR impinging directions from the ISM can affect chaos levels.
+The heliosphere has an intrinsic directionality that affects CRs differently
+depending on where they enter it. This feature causes preferential directions
+from which particles tend to be more chaotic than others. This eventually
+translates into changes in the arrival maps which are not uniformly
+distributed. Instead, we expect sectors in the map to change separately from
+others, creating a time variation that could be detected. Consequently, this
+result points to the idea that time-variability in the maps is essential to
+understanding the CR anisotropy's overall processes.",2301.10065v1
+2023-02-09,Minimal entropy production in the presence of anisotropic fluctuations,"Anisotropy in temperature, chemical potential, or ion concentration, provides
+the fuel that feeds dynamical processes that sustain life. At the same time,
+anisotropy is a root cause of incurred losses manifested as entropy production.
+In this work we consider a rudimentary model of an overdamped stochastic
+thermodynamic system in an anisotropic temperature heat bath, and study minimum
+entropy production when driving the system between thermodynamic states in
+finite time. While entropy production in isotropic temperature environments can
+be expressed in terms of the length (in the Wasserstein-2 metric) traversed by
+the thermodynamic state of the system, anisotropy complicates substantially the
+mechanism of entropy production since, besides dissipation, seepage of energy
+between ambient anisotropic heat sources by way of the system dynamics is often
+a major contributing factor. A key result of the paper is to show that in the
+presence of anisotropy, minimization of entropy production can once again be
+expressed via a modified Optimal Mass Transport (OMT) problem. However, in
+contrast to the isotropic situation that leads to a classical OMT problem and a
+Wasserstein length, entropy production may not be identically zero when the
+thermodynamic state remains unchanged (unless one has control over
+non-conservative forces); this is due to the fact that maintaining a
+Non-Equilibrium Steady-State (NESS) incurs an intrinsic entropic cost that can
+be traced back to a seepage of heat between heat baths. As alluded to, NESSs
+represent hallmarks of life, since living matter by necessity operates far from
+equilibrium. Therefore, the question studied herein, to characterize minimal
+entropy production in anisotropic environments, appears of central importance
+in biological processes and on how such processes may have evolved to optimize
+for available usage of resources.",2302.04401v1
+2023-02-17,Quasi-classical Langmuir wave collapse in a magnetic field,"The anisotropy due to a magnetic field is shown to result in significant
+changes in Langmuir collapse. Using a variational approach, the quasi-classical
+collapse phenomenon is investigated analytically.
+  A hierarchy of quasi-classical collapses is determined, along with the
+structure of a field in the proximity of a stationary singularity that is
+sustained by the continuous absorption of wave energy from a wave packet.",2302.08972v1
+2023-04-07,Linear stability analysis of non-isothermal plane Couette flow in an anisotropic and inhomogeneous porous layer underlying a fluid layer,"This paper carries out a linear stability analysis of a plane Couette flow in
+a porous layer underlying a fluid layer where the porous layer is anisotropic
+and inhomogeneous. The plane Couette flow is induced due to the uniform
+movement of the upper plate and convection arises due to the maintenance of the
+temperature difference between the upper plate and the lower plate. The fluid
+considered is Newtonian and incompressible. Darcy model is used to narrate the
+flow in the porous layer and at the interface, the Beavers-Joseph condition is
+used. The Chebyshev collocation method is used to solve the generalized
+eigenvalue problem. Here, the effect of anisotropy and inhomogeneity of the
+porous medium, along with the ratio of the thickness of fluid to porous layer,
+i.e., depth ratio $(\hat{d})$, Reynolds number $(Re)$ and Darcy number
+$(\delta)$ are studied. The analysis is carried out majorly for water; however,
+the impact of anisotropy and inhomogeneity on different fluids by varying
+Prandtl number ($Pr$) is also studied. Depending on the value of parameters,
+the unimodal (porous mode or fluid mode), bimodal (porous mode and fluid mode)
+and also trimodal (porous mode, fluid mode and porous mode) nature of the
+neutral curve is obtained. The increasing value of the inhomogeneity parameter,
+depth ratio or decreasing value of the anisotropy parameter, Reynolds number,
+Prandtl number and Darcy number raises the system instability. For
+$\delta=0.002$, $Pr=6.9$ and $Re=10$, dominating nature of porous mode is
+always observed for $\hat{d}<0.07$, and fluid mode for $\hat{d}>0.21$
+irrespective of anisotropy and inhomogeneity parameter. With the help of energy
+budget analysis, the types of instability are categorized and also the types of
+mode obtained from linear stability analysis are verified. Secondary flow
+patterns are also visualized to understand the flow dynamics.",2304.03499v1
+2023-04-26,Some aspects of anisotropic curvature flow of planar partitions,"We consider the geometric evolution of a network in the plane, flowing by
+anisotropic curvature. We discuss local existence of a classical solution in
+the presence of several smooth anisotropies. Next, we discuss some aspects of
+the polycrystalline case.",2304.13454v1
+2023-04-30,Inverse source problem for the Boltzmann equation in cosmology,"We study the inverse problem of recovering primordial perturbations from
+anisotropies of Cosmic Microwave Background (CMB) using the kinetic model.
+Mathematically, the problem in concern is the inverse source problem for the
+linear Boltzmann equation with measurements on some Cauchy surface. We obtain
+two stable determination results for generic absorption coefficients and
+scattering kernels.",2305.00560v1
+2023-05-21,Small-amplitude Compressible Magnetohydrodynamic Turbulence Modulated by Collisionless Damping in Earth's Magnetosheath: Observation Matches Theory,"Plasma turbulence is a ubiquitous dynamical process that transfers energy
+across many spatial and temporal scales and affects energetic particle
+transport. Recent advances in the understanding of compressible
+magnetohydrodynamic (MHD) turbulence demonstrate the important role of damping
+in shaping energy distributions on small scales, yet its observational evidence
+is still lacking. This study provides the first observational evidence of
+substantial collisionless damping (CD) modulation on small-amplitude
+compressible MHD turbulence cascade in Earth's magnetosheath using four Cluster
+spacecraft. Based on an improved compressible MHD decomposition algorithm,
+turbulence is decomposed into three eigenmodes: incompressible Alfv\'en modes,
+and compressible slow and fast (magnetosonic) modes. Our observations
+demonstrate that CD enhances the anisotropy of compressible MHD modes because
+CD has a strong dependence on wave propagation angle. The wavenumber
+distributions of slow modes are mainly stretched perpendicular to the
+background magnetic field ($\mathbf{B_0}$) and weakly modulated by CD. In
+contrast, fast modes are subjected to a more significant CD modulation. Fast
+modes exhibit a weak, scale-independent anisotropy above the CD truncation
+scale. Below the CD truncation scale, the anisotropy of fast modes enhances as
+wavenumbers increase. As a result, fast mode fractions in the total energy of
+compressible modes decrease with the increase of perpendicular wavenumber (to
+$\mathbf{B_0}$) or wave propagation angle. Our findings reveal how the
+turbulence cascade is shaped by CD and its consequences to anisotropies in the
+space environment.",2305.12507v3
+2023-06-07,Emergent Magnetic Phases and Piezomagnetic Effects in Mn$_x$Ni$_{1-x}$F$_2$ Thin Film Alloys,"The effect of random competing single-ion anisotropies in antiferromagnets
+was studied using epitaxial Mn$_x$Ni$_{1-x}$F$_2$ antiferromagnetic thin film
+alloys grown via molecular beam epitaxy. The crystal structure of this material
+is tetragonal for all values of $x$, and the Mn sites have a magnetic easy axis
+single-ion anisotropy while the Ni sites have an easy plane anisotropy
+perpendicular to the Mn easy axis. Crystallographic and magnetization
+measurements demonstrated that the thin film alloys were homogeneously mixed
+and did not phase-separate into their constituent parts. Pure MnF$_2$ thin
+films epitaxially grown on MgF$_2$ exhibited compressive strain along all three
+crystallographic axes which resulted in piezomagnetic effects. The
+piezomagnetism disappeared if the film was grown on a (MnNi)F$_2$ graded buffer
+layer. A mean-field theory fit to the transition temperature as a function of
+the Mn concentration $x$, which takes into account piezomagnetic effects, gave
+a magnetic exchange constant between Mn and Ni ions of $J_{\text{MnNi}} = 0.305
+\pm 0.003$~meV. Mean-field theory calculations also predicted the existence of
+an oblique antiferromagnetic phase in the Mn$_x$Ni$_{1-x}$F$_2$ alloy which
+agreed with the experimental data. A magnetic phase diagram for
+Mn$_x$Ni$_{1-x}$F$_2$ thin film alloys was constructed and showed evidence for
+the existence of two unique magnetic phases, in addition to the ordinary
+antiferromagnetic and paramagnetic phases: an oblique antiferromagnetic phase,
+and an emergent magnetic phase proposed to be either a magnetic glassy phase or
+a helical phase. The phase diagram is quantitatively different from that of
+Fe$_x$Ni$_{1-x}$F$_2$ because of the much larger single-ion anisotropy of
+Fe$^{2+}$ compared to Mn$^{2+}$.",2306.04809v2
+2023-07-06,"Chaos, Cosmic Ray Anisotropy, and the Heliosphere","After more than a century of discovering cosmic rays, a comprehensive
+description of their origin, propagation, and composition still eludes us. One
+of the difficulties is that these particles interact with magnetic fields;
+therefore, their directional information is distorted as they travel. In
+addition, as cosmic rays (CRs) propagate in the Galaxy, they can be affected by
+magnetic structures that temporarily trap them and cause their trajectories to
+display chaotic behavior, therefore modifying the simple diffusion scenario.
+Here, we examine the effects of chaos and trapping on the TeV CR anisotropy.
+Concretely, we develop a new method to study the chaotic behavior of CRs. This
+work is based on the heliospheric effects since they can be remarkably
+significant for this anisotropy. Specifically, how the distinct heliospheric
+structures can affect chaos levels. We model the heliosphere as a coherent
+magnetic structure given by a static magnetic bottle and the presence of
+temporal magnetic perturbations. This configuration is used to describe the
+draping of the local interstellar magnetic field lines around the heliosphere
+and the effects of magnetic field reversals induced by the solar cycles. In
+this work, we explore the possibility that particle trajectories may develop
+chaotic behavior while traversing and being temporarily trapped in this
+heliospheric-inspired toy model and its potential consequences on the CR
+arrival distribution. It was found that the level of chaos in a trajectory is
+linked to the time the particles remain trapped in the system. This relation is
+described by a power law that could prove to be inherently characteristic of
+the system. Also, the arrival distribution maps show areas where the different
+chaotic behaviors are present, which can constitute a source of
+time-variability in the CR maps and can prove critical in understanding the
+anisotropy on Earth.",2307.05515v1
+2023-07-25,Interplay Between Anisotropy- and Skewness-driven Whistler Instabilities in the Solar Wind under the Core-Strahlo model,"Temperature anisotropy and field-aligned skewness are commonly observed
+non-thermal features in electron velocity distributions in the solar wind.
+These characteristics can act as a source of free energy to destabilize
+different electromagnetic wave modes, which may alter the plasma state through
+wave-particle interactions. Previous theoretical studies have mainly focused on
+analyzing these non-thermal features and self-generated instabilities
+individually. However, to obtain a more accurate and realistic understanding of
+kinetic processes in the solar wind, it is necessary to examine the interplay
+between these two energy sources. By means of linear kinetic theory, in this
+paper we investigate the excitation of the parallel-propagating whistler mode,
+when it is destabilized by electron populations exhibiting both temperature
+anisotropy and field-aligned strahl or skewness. To describe the solar wind
+electrons, we adopt the Core-Strahlo model as an alternative approach. This
+model offers the advantage of representing the suprathermal features of halo
+and strahl electrons, using a single skew-Kappa distribution already known as
+the strahlo population. Our findings show that when the electron strahlo
+exhibits an intrinsic temperature anisotropy, this suprathermal population
+becomes a stronger and more efficient source of free energy for destabilizing
+the whistler mode. This suggests a greater involvement of the anisotropic
+strahlo in processes conditioned by wave-particle interactions. Present results
+also suggest that the contribution of core anisotropy can be safely disregarded
+when assessing the importance of instabilities driven by the suprathermal
+population. This allows for a focused study, particularly regarding the
+regulation of electron heat flux in the solar wind.",2307.13630v1
+2023-09-15,"A comparative ab-initio investigation of the physical properties of cubic Laves phase compounds XBi$_2$ (X = K, Rb)","In this study, we looked into a number of physical properties of
+alkali-bismuth compounds KBi$_2$ and RbBi$_2$ in the cubic Laves phase using
+the density functional theory (DFT). The structural, elastic, anisotropy
+indices, hardness, thermo-physical parameters, electronic band structure, and
+optoelectronic properties have been explored. Most of the results presented in
+this work are novel in nature.",2309.08307v1
+2023-10-18,Testing the cosmological principle with the Pantheon+ sample and the region-fitting method,"The cosmological principle is fundamental to the standard cosmological model.
+It assumes that the Universe is homogeneous and isotropic on very large scales.
+As the basic assumption, it must stand the test of various observations. In
+this work, using the region fitting (RF) method, we mapped the all-sky
+distribution of cosmological parameters ($\Omega_{m}$ and $H_{0}$) and find
+that the distribution significantly deviates from isotropy. A local matter
+underdensity region exists toward (${308.4^{\circ}}$$_{-48.7}^{+47.6}$,
+${-18.2^{\circ}}$$_{-28.8}^{+21.1}$) as well as a preferred direction of the
+cosmic anisotropy (${313.4^{\circ}}$$_{-18.2}^{+19.6}$,
+${-16.8^{\circ}}$$_{-10.7}^{+11.1}$) in galactic coordinates. Similar
+directions may imply that local matter density might be responsible for the
+anisotropy of the accelerated expansion of the Universe. Results of statistical
+isotropy analyses including Isotropy and Isotropy with real-data positions (RP)
+show high confidence levels. For the local matter underdensity, the statistical
+significances are 2.78$\sigma$ (isotropy) and 2.34$\sigma$ (isotropy RP). For
+the cosmic anisotropy, the statistical significances are 3.96$\sigma$
+(isotropy) and 3.15$\sigma$ (isotropy RP). The comparison of these two kinds of
+statistical isotropy analyses suggests that inhomogeneous spatial distribution
+of real sample can increase the deviation from isotropy. The similar results
+and findings are also found from reanalyses of the low-redshift sample (lp+)
+and the lower screening angle ($\theta_\mathrm{max}$ = 60$^{\circ}$), but with
+a slight decrease in statistical significance. Overall, our results provide
+clear indications for a possible cosmic anisotropy. This possibility must be
+taken seriously. Further testing is needed to better understand this signal.",2310.11727v2
+2023-10-18,Spacecraft Charging of the Morazán MRZ-SAT Satellite in Low Earth Orbit: Initial Results on the Influence of Energetic Electron Anisotropy on Differential Charging,"The advent of the modular CubeSat satellite architecture has heralded a
+revolution in satellite missions, drastically lowering the technical and
+financial barriers to space. Surface charging resulting from energetic electron
+poses a direct risk to satellites in space, causing electric arcing and
+breakdowns. This risk is exacerbated for small technology demonstration
+CubeSats that are less resilient than larger satellites. An upcoming CubeSat
+launch is the first CubeSat project originating from Honduras, the Moraz\'an
+satellite (MRZ-SAT), due to launch in 2024. This will carry earth observational
+payloads to detect natural disasters. This study conducts simulations using the
+Electro-Magnetic Spacecraft Environment Simulator code to study absolute and
+differential charging of the MRZ-SAT cube-sat in Low Earth Orbit (LEO). The
+MRZ-SAT hosts four antennas, an architecture which lends itself well to
+studying and understanding differential charging in LEO. The MRZ-SAT was first
+simulated in a typical benign ionospheric plasma environment. Here the antenna
+located in the ambient plasma wake displayed the maximum charging up to --0.9
+V, 0.24 V biased to the main cube. An energetic electron population was then
+included and the wake antenna subsequently charged to greater values of --2.73
+V, now 1.56 V biased to the main cube. The anisotropy of the energetic
+electrons was then varied, and this differential charging trend appeared
+exacerbated with anisotropies of 0.5 to 0.05 inducing absolute wake antenna
+voltages up to --4.5 V and differential voltage biases 50 and 100 \% greater
+than when an isotropic population was considered. This study highlights the
+importance of electron anisotropy in LEO to surface charging and identifies
+this property in the energetic electron distribution functions as inducing
+potentially greater risks to satellites of electrical arcing and breakdown.",2310.11803v1
+2024-01-25,Few-magnon excitations in a frustrated spin-$S$ ferromagnetic chain with single-ion anisotropy,"We study few-magnon excitations in a finite-size spin-$S$ chain with
+ferromagnetic nearest-neighbor (NN) interaction $J>0$ and antiferromagnetic
+next-nearest-neighbor (NNN) interaction $J'<0$, in the presence of the
+single-ion (SI) anisotropy $D$. We first reveal the condition for the emergence
+of zero-excitation-energy states. In the isotropic case with $\Delta=\Delta'=1$
+($\Delta$ and $\Delta'$ are the corresponding anisotropy parameters), a
+threshold of $J/|J'|$ above which the ground state is ferromagnetic is
+determined by exact diagonalization for short chains up to $12$ sites. Using a
+set of exact two-magnon Bloch states, we then map the two-magnon problem to a
+single-particle one on an effective open chain with both NN and NNN hoppings.
+The whole two-magnon excitation spectrum is calculated for large systems and
+the commensurate-incommensurate transition in the lowest-lying mode is found to
+exhibit different behaviors between $S=1/2$ and higher spins due to the
+interplay of the SI anisotropy and the NNN interaction. For the commensurate
+momentum $k=-\pi$, the effective lattice is decoupled into two NN open chains
+that can be exactly solved via a plane-wave ansatz. Based on this, we
+analytically identify in the $\Delta'-D/|J'|$ plane the regions supporting the
+SI or NNN exchange two-magnon bound states near the edge of the band. In
+particular, we prove that there always exists a lower-lying NN exchange
+two-magnon bound state near the band edge for arbitrary $S\geq 1/2$. Finally,
+we numerically calculate the $n$-magnon spectra for $S=1/2$ with $n\leq5$ by
+using a spin-operator matrix element method. The corresponding $n$-magnon
+commensurate instability regions are determined for finite chains and
+consistent results with prior literature are observed.",2401.14101v2
+2024-03-05,Anomalous continuum scattering and higher-order van Hove singularity in the strongly anisotropic S = 1/2 triangular lattice antiferromagnet,"The S = 1/2 triangular lattice antiferromagnet (TLAF) stands out as a
+paradigmatic example of frustrated quantum magnetism. An ongoing challenge
+involves understanding the influence of exchange anisotropy on the collective
+behavior within such systems. Using inelastic neutron scattering (INS) and
+advanced calculation techniques, we have studied the low and high temperature
+spin dynamics of Ba2La2CoTe2O12 (BLCTO): a Co2+-based Jeff = 1/2 TLAF that
+exhibits 120 deg order below TN = 3.26 K. The spin Hamiltonian was determined
+by fitting the energy-resolved paramagnetic excitations measured at T > TN,
+revealing an exceptionally strong easy-plane XXZ exchange anisotropy. Below TN,
+the excitation spectrum exhibits a high energy continuum having a larger
+spectral weight than the single-magnon modes. Combined with advanced
+theoretical calculations of magnetic excitations based on magnons and spinons,
+this observation suggests a scenario characterized by a spinon confinement
+length that markedly exceeds the lattice spacing. We conjecture that this
+phenomenon arises due to the proximity to a quantum melting point, which
+persists even in the presence of strong easy-plane XXZ anisotropy. Finally, we
+highlight characteristic flat features in the excitation spectrum, which are
+connected to higher-order van Hove singularities in the magnon dispersion and
+are directly induced by easy-plane XXZ anisotropy. Our results provide a rare
+experimental insight into the nature of highly anisotropic S = 1/2 TLAFs
+between the Heisenberg and XY limits.",2403.03210v1
+1992-08-27,"COBE, Gravitational Waves, Inflation and Extended Inflation","We analyse the implications for inflationary models of the cosmic microwave
+background (cmb) anisotropy measured by COBE. Vacuum fluctuations during
+inflation generate an adiabatic density perturbation, and also gravitational
+waves. The ratio of these two contributions to the cmb anisotropy is given for
+an arbitrary slow-roll inflaton potential. Results from the IRAS/QDOT and
+POTENT galaxy surveys are used to normalise the spectrum of the density
+perturbation on the scale $20h^{-1}\Mpc$, so that the COBE measurement on the
+scale $10^3h^{-1}\Mpc$ provides a lower bound on the spectral index $n$. For
+`power law' and `extended' inflation, gravitational waves are significant and
+the bound is $n>0.84$ at the $2$-sigma level. For `natural' inflation,
+gravitational waves are negligible and the constraint is weakened to $n>0.70$,
+at best marginally consistent with a recent proposal for explaining the excess
+clustering observed in the APM galaxy survey. Many versions of extended
+inflation, including those based on the Brans--Dicke theory, are ruled out,
+because they require $n\lsim 0.75$ in order that bubbles formed at the end of
+inflation should not be observed now in the cmb.",9208007v2
+1993-01-07,Microwave Anisotropies in the Light of COBE,"The recent COBE measurement of anisotropies in the cosmic microwave
+background and the recent South Pole experiment of Gaier {\it et al.} offer an
+excellent opportunity to probe cosmological theories. We test a class of
+theories in which the Universe today is flat and matter dominated, and
+primordial perturbations are adiabatic parameterized by an index $n$. In this
+class of theories the predicted signal in the South Pole experiment depends not
+only on $n$, but also on the Hubble constant and the baryon density. For $n=1$
+a large region of this parameter space is ruled out, but there is still a
+window open which satisfies constraints coming from COBE, measurements of the
+age of the Universe, the South Pole experiment, and big bang nucleosynthesis.
+Using the central values of the Hubble constant and baryon density favored by
+nucleosynthesis and age measurements, we find that, even if the COBE
+normalization drops by $1\sigma$, $n > 1.2$ is ruled out.",9301002v1
+1993-06-30,Tensor Perturbations in Inflationary Models as a Probe of Cosmology,"In principle, the tensor metric (gravity-wave) perturbations that arise in
+inflationary models can, beyond probing the underlying inflationary model,
+provide information about the Universe: ionization history, presence of a
+cosmological constant, and epoch of matter-radiation equality. Because tensor
+perturbations give rise to anisotropy of the cosmic background radiation (CBR)
+solely through the Sachs-Wolfe effect we are able to calculate analytically the
+variance of the multipole moments of this part of the CBR temperature
+anisotropy. In so doing, we carefully take account of the contribution of
+tensor perturbations that entered the Hubble radius during both the
+matter-dominated and radiation-dominated epoch by means of a transfer function.
+The striking feature in the spectrum of multipole amplitudes is a dramatic fall
+off for $l\ga \sqrt{1+\zl}$, where $\zl$ is the red shift of the
+last-scattering surface. ...",9306029v1
+1993-11-02,Microwave Background Anisotropies in Primeval Isocurvature Baryon Models: Constraints on the Cosmological Parameters,"We have performed the most comprehensive predictions of the temperature
+fluctuations \dtt in the primeval isocurvature baryon models to see whether or
+not the models are consistent with the recent data on the cosmic microwave
+background anisotropies. More specifically, we computed the \dtt corresponding
+to the experimental set-up by the South-Pole and the Owens Valley experiments
+as well as the COBE satellite. The amplitudes of the predicted \dtt are
+normalized by means of the COBE 10$^\circ$ data. The resulting constraints on
+the models are presented on $n - \Omega_b$ plane in the case of
+$\lambda_0=1-\Omega_b$ (flat models) and $\lambda_0=0$ (open models), where $n$
+is the primordial spectral index of entropy fluctuations and $\Omega_b$ is the
+present baryon density parameter.
+  Our results imply that the PIB models cannot be reconciled with the current
+observations for any reasonable set of cosmological parameters.",9311012v1
+1993-11-15,The Spatial Correlation Function from an X--ray Selected Sample of Abell Clusters,"We present here the Spatial Two--Point Correlation Function for a complete
+sample of 67 X--ray selected Abell clusters of galaxies. We find a correlation
+length of $16.1\pm3.4\mpc$ with no significant clustering beyond
+$\simeq40\mpc$. This is the lowest uncorrected value for the correlation length
+ever derived from the Abell catalogue of clusters. In addition, we have
+investigated the anisotropy of the correlation function between the radial and
+transverse directions. This can be characterised by the magnitude of pair--wise
+cluster peculiar velocities such anisotropy predicts, which we find to be
+$\simeq800{\rm km\,s^{-1}}$ for our sample. Again, this is the lowest
+uncorrected value ever seen for the Abell catalogue. We therefore, no longer
+need to invoke high cluster peculiar velocities or line of sight clustering to
+understand the correlation function as derived from an Abell sample of
+clusters. Furthermore, our result is consistent with recently published
+correlation functions computed from automated selections of optical and X--ray
+clusters. Therefore, we are now approaching a coherent picture for the form of
+the cluster spatial correlation function which will be used to place confident
+constraints on theories of galaxy formation.",9311033v1
+1993-12-03,The Angular Bispectrum of The Cosmic Microwave Background,"COBE has provided us with a whole-sky map of the CBR anisotropies. However,
+even if the noise level is negligible when the four year COBE data are
+available, the cosmic variance will prevent us from obtaining information about
+the Gaussian nature of the primordial fluctuations. This important issue is
+addressed here by studying the angular bispectrum of the cosmic microwave
+background anisotropies. A general form of the angular bispectrum is given and
+the cosmic variance of the angular bispectrum for Gaussian fluctuations is
+calculated. The advantage of using the angular bispectrum is that one can
+choose to use the multipole moments which minimize the cosmic variance term.
+The non-Gaussian signals in most physically motivated non-Gaussian models are
+small compared with cosmic variance. Unless the amplitudes are large, the
+non-Gaussian signals are only detectable in the COBE data in those models where
+the angular bispectrum is flat or increases with increasing multipole moment.",9312004v2
+1993-12-17,Anisotropy in the Angular Broadening of Sgr A$^*$ at the Galactic Center,"We present the results of a $\lambda$20 cm VLA observation of the compact
+Galactic center radio source Sgr A$^*$. The scatter-broadened image is
+elongated in the East-West direction, with an axial ratio of 0.6$\pm$0.05 and a
+position angle of 87$^0\pm$3$^0$. A similar shape and orientation has been
+found previously at shorter wavelengths using VLBI and VLBA. Both the major and
+minor axes follow the $\lambda^2$ law appropriate for scattering by turbulence
+in the intervening medium. Assuming that the anisotropy is caused by a magnetic
+field permeating the scattering medium, we argue that the scattering occurs
+within extended HII regions lying in the central 100 pc of the Galaxy. The
+magnetic field in this region must be poloidal, organized and is estimated to
+have a strength of at least 30 to 100 $\mu$Gauss.",9312040v1
+1993-12-23,Dipole Anisotropy in the COBE DMR First-Year Sky Maps,"We present a determination of the cosmic microwave background dipole
+amplitude and direction from the COBE Differential Microwave Radiometers (DMR)
+first year of data. Data from the six DMR channels are consistent with a
+Doppler-shifted Planck function of dipole amplitude Delta T = 3.365 +/-0.027 mK
+toward direction (l,b) = (264.4 +/- 0.3 deg, 48.4 +/- 0.5 deg). The implied
+velocity of the Local Group with respect to the CMB rest frame is 627 +/- 22
+km/s toward (l,b) = (276 +/- 3 deg, 30 +/- 3 deg). DMR has also mapped the
+dipole anisotropy resulting from the Earth's orbital motion about the Solar
+system barycenter, yielding a measurement of the monopole CMB temperature at
+31.5, 53, and 90 GHz, to be 2.75 +/- 0.05 K.",9312056v1
+1994-01-11,Observational Constraints on the Spectral Index,"We address the possibility of bounding the spectral index $n$ of primordial
+density fluctuations, using both the cosmic microwave background (cmb)
+anisotropy and data on galaxies and clusters. Each piece of galaxy and cluster
+data is reduced to a value of $\sigma(R)$ (the linearly evolved {\em rms}
+density contrast with top hat smoothing on scale $R$) which allows data on
+different scales to be readily compared. As a preliminary application, we
+normalise the spectrum using the ten degree variance of the COBE data, and then
+compare the prediction with a limited sample of low energy data, for the MDM
+model with various values of $n$, $\Omega_\nu$ and $h$. With $h=.5$, the data
+constrain the spectral index to the range $0.7\lsim n \lsim 1.2$. If
+gravitational waves contribute to the cmb anisotropy with relative strength
+$R=6(1-n)$ (as in some models of inflation), the lower limit on $n$ is
+increased to about $0.85$. The uncertainty in $h$ widens this band by about
+$0.1$ at either end.",9401014v2
+1994-01-11,Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer,"The angular power spectrum estimator developed by Peebles (1973) and Hauser &
+Peebles (1973) has been modified and applied to the 2 year maps produced by the
+COBE DMR. The power spectrum of the real sky has been compared to the power
+spectra of a large number of simulated random skies produced with noise equal
+to the observed noise and primordial density fluctuation power spectra of power
+law form, with $P(k) \propto k^n$. Within the limited range of spatial scales
+covered by the COBE DMR, corresponding to spherical harmonic indices $3 \leq
+\ell \lsim 30$, the best fitting value of the spectral index is $n =
+1.25^{+0.4}_{-0.45}$ with the Harrison-Zeldovich value $n = 1$ approximately
+0.5$\sigma$ below the best fit. For $3 \leq \ell \lsim 19$, the best fit is $n
+= 1.46^{+0.39}_{-0.44}$. Comparing the COBE DMR $\Delta T/T$ at small $\ell$ to
+the $\Delta T/T$ at $\ell \approx 50$ from degree scale anisotropy experiments
+gives a smaller range of acceptable spectral indices which includes $n = 1$.",9401015v2
+1994-02-11,Is a Massive Tau Neutrino Just What Cold Dark Matter Needs?,"The cold dark matter (CDM) scenario for structure formation in the Universe
+is very attractive and has many successes; however, when its spectrum of
+density perturbations is normalized to the COBE anisotropy measurement the
+level of inhomogeneity predicted on small scales is too large. This can be
+remedied by a tau neutrino of mass $1\MeV - 10\MeV$ and lifetime $0.1\sec -
+100\sec$ whose decay products include electron neutrinos because it allows the
+total energy density in relativistic particles to be doubled without
+interfering with nucleosynthesis. The anisotropies predicted on the degree
+scale for ``$\tau$CDM'' are larger than standard CDM. Experiments at $e^\pm$
+colliders may be able to probe such a mass range.",9402028v1
+1994-04-07,The Amplitude and Spectral Index of the Large Angular Scale Anisotropy in the Cosmic Microwave Background Radiation,"In many cosmological models, the large angular scale anisotropy in the cosmic
+microwave background is parameterized by a spectral index, $n$, and a
+quadrupolar amplitude, $Q$. For a Peebles-Harrison-Zel'dovich spectrum, $n=1$.
+Using data from the Far Infra-Red Survey (FIRS) and a new statistical measure,
+a contour plot of the likelihood for cosmological models for which $-1 < n < 3$
+and $0 \le Q \le 50~\mu{\rm K}$ is obtained. We find that the likelihood is
+maximum at $(n, Q) = (1.0, 19 uK)$. For constant $n$ the likelihood falls to
+half its maximum at $Q \approx 14 uK$ and $25 uK$ and for constant $Q$ the
+likelihood falls to half its maximum at $n \approx 0.5$ and $1.4$. Regardless
+of $Q$, the likelihood is always less than half its maximum for $n < -0.4$ and
+for $n > 2.2$, as it is for $Q < 8 uK$ and $Q > 44$.",9404009v1
+1994-05-12,Black Hole Relics and Inflation: Limits on Blue Perturbation Spectra,"Blue primordial power spectra have spectral index $n>1$ and arise naturally
+in the recently proposed hybrid inflationary scenario. An observational upper
+limit on {\em n} is derived by normalizing the spectrum at the quadrupole scale
+and considering the possible overproduction of Planck mass relics formed in the
+final stage of primordial black hole evaporation. In the inflationary Universe
+with the maximum reheating temperature compatible with the observed quadrupole
+anisotropy, the upper limit is $n=1.4$, but it is slightly weaker for lower
+reheat temperatures. This limit applies over 57 decades of mass and is
+therefore insensitive to cosmic variance and any gravitational wave
+contribution to the quadrupole anisotropy. It is also independent of the dark
+matter content of the Universe and therefore the bias parameter. In some
+circumstances, there may be an extended dust-like phase between the end of
+inflation and reheating. In this case, primordial black holes form more
+abundantly and the upper limit is $n=1.3$.",9405027v1
+1994-06-14,Polarization and Anisotropy of the Microwave Sky,"We study the polarization-polarization and polarization-temperature
+correlations in standard adiabatic scenarios for structure formation.
+Temperature anisotropies due to gravitational potential wells and oscillations
+in the photon-baryon-electron fluid on the surface of last scattering are each
+associated with a correlated polarization pattern. While the `correlated part'
+of the polarization has an r.m.s. of only a third of the total signal, it may
+still be measurable by mapping a large area on the sky. We calculate the
+expected signal to noise ratio for various measures of the polarization in a
+hypothetical mapping experiment such as those now being planned.",9406046v2
+1994-08-12,CMB Maps at 0.5 degree Resolution I: Full-Sky Simulations and Basic Results,"We have simulated full-sky maps of the Cosmic Microwave Background (CMB)
+anisotropy expected from Cold Dark Matter (CDM) models at 0.5 and 1.0 degree
+angular resolution. Statistical properties of the maps are presented as a
+function of sky coverage, angular resolution, and instrument noise, and the
+implications of these results for observability of the Doppler peak are
+discussed. The rms fluctuations in a map are not a particularly robust probe of
+the existence of a Doppler peak, however, a full correlation analysis can
+provide reasonable sensitivity. We find that sensitivity to the Doppler peak
+depends primarily on the fraction of sky covered, and only secondarily on the
+angular resolution and noise level. Color plates and one-dimensional scans of
+the maps are presented to visually illustrate the anisotropies.",9408037v1
+1994-09-13,Optimizing Observing Patterns in Cosmic Microwave Background Radiation Anisotropy Experiments,"We consider several factors concerning the design of observing strategies in
+Cosmic Microwave Background (CMB) anisotropy experiments. First we consider the
+number of independent points on the sky one should observe given a fixed
+observing time. Given an assumed level of sky temperature fluctuations,
+$\sigma_{sky}$ and the presence of instrumental noise $s$ in units of K
+s$^{-1/2}$ and a total observing time $t_{obs}$, we find there is an optimum
+number of points in the sky to maximize the confidence level of a detection.
+This number is a function of the signal to noise ratio $R^2 = \sigma_{sky}^2
+t_{obs}/s^2$. We verify this analytical result with a monte carlo simulation,
+which also includes the correlation between different positions in the sky.
+Furthermore, using an $n=1$ spectrum of Gaussian fluctuations, we show that
+arranging the observing patterns along a (great) circle, a raster scan, or a
+randomized pattern yields results which are indistinguishable in Monte carlos.",9409031v1
+1994-12-05,"Cosmological Inflation, Microwave Background Anisotropies and Large Scale Structure of the Universe","Cosmological inflation provides the simplest and most promising mechanism for
+generating fluctuations for structure formation. Using powerful Hamilton-Jacobi
+methods, I will describe (1) how to compute density fluctuations and cosmic
+microwave anisotropies arising from inflation, and (2) improvements of the
+Zel'dovich approximation describing gravitational collapse. I compare these
+results with the latest cosmological observations.",9412012v2
+1994-12-07,Degree Scale Anisotropy: Current Status,"The Cosmic Background Radiation gives us one of the few probes into the
+density perturbations in the early universe that should later lead to the
+formation of structure we now observe. Recent advances in degree scale
+anisotropy measurements have allowed us to begin critically testing
+cosmological models. Combined with the larger scale measurements from COBE we
+are now able to directly compare data and theory. These measurements promise
+future progress in understanding structure formation. Because of the extreme
+sensitivities needed (1-10 ppm) and the difficulties of foreground sources,
+these measurements require not only technological advances in detector and
+measurement techniques, but multi spectral measurements and careful attention
+to low level systematic errors. This field is advancing rapidly and is in a
+true discovery mode. Our own group has been involved in a series of eleven
+experiments over the last six years using the ACME (Advanced Cosmic Microwave
+Explorer) payload which has made measurements at angular scales from 0.3 to 3
+degrees and over a wavelength range from 1 to 10 mm. The recent data from these
+and other measurements will be reviewed as well as some of the challenges and
+potential involved in these and future measurements.",9412021v1
+1994-12-09,No Very Large Scale Structure in an Open Universe,"We study the effects of negative spatial curvature on the statistics of
+inhomogeneities in open cosmological models. In particular we examine the
+suppression of large-separation correlations in density and gravitational
+potential fluctuations and the resulting suppression of large-angle
+correlations in the anisotropy of the microwave background radiation. We obtain
+an expression which gives the {\it minimum} amount of suppression of
+correlations for any statistical distribution described by a ``power
+spectrum''. This minimum suppression requires that the correlations fall off
+exponentially above the curvature scale. To the extent that the observed
+correlations in the temperature anisotropy extend to large angular scales, one
+can set a lower bound to the radius of curvature and hence on $\Omega_0$.",9412031v1
+1995-01-10,COBE Constraints on Baryon Isocurvature Models,"We consider Bayesian constraints on standard isocurvature baryon models from
+the slope and normalization of the anisotropy power spectrum detected by the
+COBE DMR experiment in their two year maps. In conjunction with either the
+amplitude of matter fluctuations $\sigma_8$ {\it or} its slope, all open models
+are ruled out at greater than 95\% confidence, whereas cosmological constant
+$\Lambda$ dominated models are constrained to be highly ionized. By including
+the COBE FIRAS 95\% confidence upper limit on spectral distortion, we further
+reduce the available parameter space for $\Lambda$ models by excluding these
+highly ionized models. These constraints define a single class of barely viable
+standard models which makes definite and testable predictions for degree scale
+anisotropies and large scale structure.",9501034v1
+1995-01-17,Velocity profiles of Osipkov-Merritt models,"A simple algorithm is presented for the calculation of the projected
+line-of-sight velocity profiles (VPs) of non-rotating anisotropic spherical
+stellar dynamical models with a phase-space distribution function of the
+Osipkov-Merritt type. The velocity distribution in these models is isotropic
+inside the anisotropy radius r_a and becomes increasingly radially biased at
+larger radii. VP shape parameters are presented for a family of models in which
+the luminous mass density has an r^{-gamma} power-law cusp at small radii and
+an r^{-4} power-law fall-off at large radii. Self-consistent models and models
+in which the luminous matter is embedded in a dark halo are discussed. The
+effects of changes in the cusp slope gamma and in the anisotropy radius r_a are
+documented, and the area in the (gamma,r_a)-plane that contains physical models
+is delineated. The shapes of the VPs of the models show a considerable (and
+observable) variation with projected galactocentric radius. These models will
+be useful for interpreting the data on the VP shapes of elliptical galaxies
+that are now becoming available.",9501054v1
+1995-01-31,Large Angle CMB Anisotropy in an Open Universe in the One-Bubble Inflationary Scenario,"We consider an alternative scenario of inflation which can account for a
+spatially open universe. It is similar to the old inflation in which the bubble
+nucleation occurs in the sea of false vacuum, but differs from it in that the
+second slow rollover inflation occurs inside a nucleated bubble. Hence our
+observable universe is entirely contained in one nucleated bubble. The
+significance of the scenario is that apart from a variance due to model
+parameters it gives us a definite prediction on the spectrum of the primordial
+density perturbations, hence is observationally testable. Here we investigate
+the spectrum of CMB anisotropies on large angular scales. We find that the
+contribution from peculiar modes which never appear in the usual harmonic
+analysis is significant in the case $\Omega_0\lesssim0.1$.",9501109v1
+1995-04-12,Parallel Linear General Relativity and CMB Anisotropies,"We have developed a code which links scalar-mode fluctuations in the early
+universe with those observable at the present time by integrating the coupled,
+linearized, Einstein, Boltzmann, and fluid equations in a perturbed flat
+Robertson-Walker spacetime. The results are useful both for calculations of the
+cosmic microwave background anisotropy and the linear power spectrum of matter
+fluctuations. This paper introduces the serial and parallel codes, presents
+timing results, and gives sample output in graphical and animated form.
+  This is a latex version containing most of an HTML-format technical paper
+submitted for Supercomputing '95. The preferred method of viewing is to point
+your WWW client to http://arcturus.mit.edu/SC95/",9504040v1
+1995-04-20,CBR Anisotropy and the Running of the Scalar Spectral Index,"Accurate ($\lesssim 1\% $) predictions for the anisotropy of the Cosmic
+Background Radiation (CBR) are essential for using future high-resolution
+($\lesssim 1^\circ$) CBR maps to test cosmological models. In many inflationary
+models the variation (``running'') of the spectral index of the spectrum of
+density perturbations is a significant effect and leads to changes of around
+1\% to 10\% in the CBR power spectrum. We propose a general method for taking
+running into account which uses the derivative of the spectral index ($dn/d\ln
+k$). Conversely, high-resolution CBR maps may be able to determine $dn/d\ln k$,
+giving important information about the inflationary potential.",9504071v2
+1995-07-12,Fokker-Planck Models of Star Clusters with Anisotropic Velocity Distributions. I. Pre-Collapse Evolution,"The evolution of a spherical single-mass star cluster is followed in detail
+up to core collapse by numerically solving the orbit-averaged two-dimensional
+Fokker-Planck equation in energy-angular momentum space. Velocity anisotropy is
+allowed in the two-dimensional Fokker-Planck model. Using improved numerical
+codes, the evolution has been followed until the central density increased by a
+factor of $10^{14}$ with high numerical accuracy. The numerical results clearly
+show self-similar evolution of the core during the late stages of the core
+collapse. When Plummer's model is chosen as the initial condition, the collapse
+time is about 17.6 times the initial half-mass relaxation time. This is longer
+than the collapse time for the isotropic model by about 13%. As the result of
+strong relaxation in the core, the halo becomes to be dominated by radial
+orbits. The degree of anisotropy monotonically increases as the radius
+increases.",9507040v1
+1995-08-26,Wandering in the Background: A CMB Explorer,"We develop and examine the principles governing the formation of distortions
+in the cosmic microwave background. Distortions in the frequency or spectral
+distribution of the background probe the thermal history of the universe
+whereas those in the angular temperature distribution probe its dynamics and
+geometry. Stressing model independent results, we show how the microwave
+background can be used to extract information on the mass density, vacuum
+density, baryon content, radiation content, expansion rate and some aspects of
+structure formation in the universe. To address these issues, we systematically
+develop relativistic kinetic and perturbation theory addressing issues such as
+fluctuation representation, or gauge, normal mode analysis in an open geometry,
+and second order effects. Through analytic and numerical results, we construct
+anisotropies in a critical, open, or cosmological constant universe with
+adiabatic and/or isocurvature initial conditions allowing for possible early
+reionization. We find that anisotropy formation is a simple process governed by
+the Compton scattering of photons and electrons and their gravitational
+coupling to the other particle species in the universe.",9508126v2
+1995-08-31,Why Not Consider Closed Universes?,"We consider structure formation and CMB anisotropies in a closed universe,
+both with and without a cosmological constant. The CMB angular power spectrum
+and the matter transfer function are presented, along with a discussion of
+their relative normalization. This represents the first full numerical
+evolution of density perturbations and anisotropies in a spherical geometry. We
+extend the likelihood function vs. Omega from the COBE 2-year data to Omega>=1.
+For large Omega the presence of a very steep rise in the spectrum towards low
+ell allows us to put an upper limit of Omega<=1.5 (95%CL) for primordial
+spectra with n<=1. This compares favorably with existing limits on Omega. We
+show that there are a range of closed models which are consistent with
+observational constraints while being even older than the currently popular
+flat models with a cosmological constant. Future constraints from degree scale
+CMB data may soon probe this region of parameter space. A derivation of the
+perturbed Einstein, fluid and Boltzmann equations for open and closed
+geometries is presented in an appendix.",9508157v1
+1995-10-13,Looking for $Λ$ with the Rees-Sciama Effect,"In models with a cosmological constant, a significant component of the large
+scale cosmic microwave background (CMB) anisotropy is produced at rather low
+redshifts, z < 1. In these models, the gravitational potential perturbations
+begin to evolve at late times. Photons passing through these time varying
+potentials aquire frequency shifts, an effect first noted by Rees and Sciama.
+Since the gravitational potential is associated with matter at observable
+redshifts, the local matter density (or some tracer thereof) is correlated with
+the CMB anisotropy on the sky. We outline the optimal method of measuring this
+correlation, and discuss the prospects for using an X-ray/COBE comparison to
+detect a cosmological constant.",9510072v1
+1995-10-19,Microlensing rates from self-consistent galactic models,"We study different models of dark matter distribution for the halo of our
+galaxy. In particular, we consider Eddington and King-Michie models, which
+[C[C, which include anisotropy in the velocity space, and compute in a
+self-consistent way the amount of dark matter present in the halo. Assuming
+that the dark matter is in form of MACHOs, we find for each model the expected
+number of microlensing events and their average time duration for an experiment
+monitoring stars in the LMC. The main effect of including anisotropy is to
+reduce the microlensing rate by about 30% and to increase, but only slightly,
+the mean event duration as compared to the standard halo model. Consideration
+of different luminous models for the visible part of the galaxy also induce
+variations in the microlensing results by roughly the same amount as mentioned
+above. The main uncertainty, in order to be able to discriminate between
+different dark matter distributions and to estimate the fraction of it in form
+of MACHOs is due to the poor knowledge of the rotation velocity at large
+galactocentric distances.",9510099v1
+1995-12-20,A Fast and Accurate Algorithm for Computing Tensor CBR Anisotropy,"Inflation gives rise to a nearly scale-invariant spectrum of tensor
+perturbations (gravitational waves), their contribution to the Cosmic
+Background Radiation (CBR) anisotropy depends upon the present cosmological
+parameters as well as inflationary parameters. The analysis of a
+sampling-variance-limited CBR map offers the most promising means of detecting
+tensor perturbations, but will require evaluation of the predicted multipole
+spectrum for a very large number of cosmological parameter sets. We present
+accurate polynomial formulae for computing the predicted variance of the
+multipole moments in terms of the cosmological parameters $\Omega_\Lambda$,
+$\Omega_0h^2$, $\Omega_B h^2$, $N_{\nu}$, and the power-law index $n_T$ which
+are accurate to about 1\% for $l\le 50$ and to better than 3\% for $50< l \le
+100$ (as compared to the numerical results of a Boltzmann code).",9512140v1
+1995-12-22,Dependence of Inflationary Reconstruction upon Cosmological Parameters,"The inflationary potential and its derivatives determine the spectrum of
+scalar and tensor metric perturbations that arise from quantum fluctuations
+during inflation. The CBR anisotropy offers a promising means of determining
+the spectra of metric perturbations and thereby a means of constraining the
+inflationary potential. The relation between the metric perturbations and CBR
+anisotropy depends upon cosmological parameters -- most notably the possibility
+of a cosmological constant. Motivated by some observational evidence for a
+cosmological constant (large-scale structure, cluster-baryon fraction,
+measurements of the Hubble constant and age of the Universe) we derive the
+reconstruction equations and consistency relation to second order in the
+presence of a cosmological constant. We also clarify previous notation and
+discuss alternative schemes for reconstruction.",9512155v1
+1996-01-12,RMS Anisotropy in the COBE-DMR Four-Year Sky Maps,"The sky-RMS is the simplest model-independent characterization of a
+cosmological anisotropy signal. The RMS temperature fluctuations determined
+from the $COBE$-DMR four-year sky maps are frequency independent, consistent
+with the hypothesis that they are cosmological in origin, with a typical
+amplitude at 7 degrees of ~ 35 \pm\ 2 uK and at 10 degrees of ~29 \pm\ 1 uK. A
+joint analysis of the 7 deg and 10 deg ""cross""-RMS derived from the data in
+both Galactic and Ecliptic coordinates is used to determine the RMS quadrupole
+normalization, $Q_{rms-PS}$, for a scale-invariant Harrison-Zel'dovich power
+law model. The difference in the inferred normalizations either including or
+excluding the quadrupole is a consequence of the sensitivity of the method to
+the Galaxy contaminated observed sky quadrupole. Whilst there are variations
+depending on the data selection, all results are consistent with an inferred
+\qrms\ normalization of ~18 \pm\ 2 uK.",9601065v1
+1996-01-19,The Tilt of the Fundamental Plane of Elliptical Galaxies: I. Dynamical and Structural Effects,"In this paper we explore several structural and dynamical effects on the
+projected velocity dispersion as possible causes of the fundamental plane (FP)
+tilt of elliptical galaxies. Specifically, we determine the size of the
+systematic trend along the FP in the orbital radial anisotropy, in the dark
+matter (DM) content and distribution relative to the bright matter, and in the
+shape of the light profile that would be needed to produce the tilt, under the
+assumption of a constant stellar mass to light ratio. Spherical, non rotating,
+two--components models are constructed, where the light profiles resemble the
+$R^{1/4}$ law. For the investigated models anisotropy cannot play a major role
+in causing the tilt, while a systematic increase in the DM content and/or
+concentration may formally produce it. Also a suitable variation of the shape
+of the light profile can produce the desired effect, and there may be some
+observational hints supporting this possibility. However, fine tuning is always
+required in order to produce the tilt, while preserving the {\it tightness} of
+the galaxies distribution about the FP.",9601100v1
+1996-01-30,The Impact of the CMB on Large-Scale Structure,"The COBE detection of microwave anisotropies provides the best way of fixing
+the amplitude of cosmological fluctuations on the largest scales. We discuss
+the impact of this new, precise normalization and give fitting formulae for the
+horizon-crossing amplitude as a function of \Omega_0 and n for both open and
+flat cosmologies. We also discuss the relevant normalization (\sigma_8) at
+galaxy-clustering scales. Already it is clear that the inferred \sigma_8 can be
+unnaccepatably high for some of the simplest inflationary models, although many
+minor variants give an adequate fit. Generic topological defect models appear
+to fare rather badly, and it is unclear whether minor variants or improved
+calculations will help much. The detection and mapping of structure in the CMB
+anisotropy spectrum on smaller scales in the near future will enable us to
+achieve much stronger constraints on models.",9601170v1
+1996-02-07,Anisotropic Observations in Universes with Nonlinear Inhomogeneity,"We calculate the off--center observational relations in a spherically
+symmetric dust universe that is inhomogeneous at small redshifts. In contrast
+to the usual model, in which the CMBR dipole is interpreted as a Doppler effect
+due to peculiar velocity, our model explores an alternative interpretation, in
+which the CMBR dipole is non--Doppler, and the observer is comoving with the
+mean matter flow. We do not assume a background frame relative to which
+peculiar velocities are calculated. Our analysis is fully nonlinear and the
+density contrast is not assumed to be small. We obtain exact expressions for
+the Hubble and deceleration parameters, and find that both parameters have
+quadrupole anisotropies, but no dipoles. A simple numerical procedure for
+calculating the CMBR dipole anisotropy in our model is presented, and the
+observed 0.1% dipole is shown to be reproducible with a reasonable choices of
+parameters.",9602033v1
+1996-02-08,Probing the dynamics of cluster-lenses,"We propose a new approach to study the dynamical implications of mass models
+of clusters for the velocity structure of galaxies in the core. Strong and weak
+lensing data are used to construct the total mass profile of the cluster, which
+is used in conjunction with the optical galaxy data to solve in detail for the
+nature of galaxy orbits and the velocity anisotropy in the central regions. We
+also examine other observationally and physically motivated mass models,
+specifically those obtained from X-ray observations and N-body simulations. The
+aim of this analysis is to understand qualitatively the structure of the core
+and test some of the key assumptions of the standard picture of cluster
+formation regarding relaxation, virialization and equilibrium. This technique
+is applied to the cluster Abell 2218, where we find evidence for an anisotropic
+core, which we interpret to indicate the existence of a dynamically disturbed
+central region. We find that the requirement of physically meaningful solutions
+for the velocity anisotropy places stringent bounds on the slope of cluster
+density profiles in the inner regions.",9602035v2
+1996-04-11,Microwave Background Anisotropies Due to the Kinematic Sunyaev-Zel'dovich Effect of the Lyman-alpha Forest,"The Lyman-alpha absorption systems observed in the spectra of QSOs are likely
+to possess bulk peculiar velocities. The free electrons in these systems
+scatter the microwave background and distort its spectrum through the kinematic
+Sunyaev-Zel'dovich effect. I calculate the temperature fluctuations of the
+microwave sky due to variations in the number of Lyman-alpha systems along
+different lines-of-sight throughout the universe. The known population of
+absorbers out to z=5 introduces anisotropies on angular scales <1' with an rms
+amplitude of order (DeltaT/T)= 10^{-6}*(Omega_Lya/0.05)*(v/400km/s), where
+Omega_Lya is the cosmological density parameter of ionized gas in Lyman-alpha
+absorption systems, and v is the rms line-of-sight peculiar velocity of these
+systems at z=3. Detection of this signal will provide valuable information
+about the cosmic velocity field and the gas content of Lyman-alpha absorption
+systems at high redshifts.",9604060v1
+1996-04-18,Structure Formation in Inflationary Cosmologies,"A brief account is given of large-scale structure modelling based on the
+assumption that the initial perturbations arise from inflation. A recap is made
+of the implications of inflation for large-scale structure; under the widely
+applicable slow-roll paradigm inflation adds precisely two extra parameters to
+the normal scenarios, which can be taken to be the tilt of the density
+perturbation spectrum and the amplitude of gravitational waves. Some comments
+are made about the {\it COBE} normalization. A short description is given of an
+analysis combining cosmic microwave background anisotropy data and large-scale
+structure data to constrain cosmological parameters, and the case of cold dark
+matter models with a cosmological constant is used as a specific illustration.",9604105v1
+1996-04-25,A Detection of Bright Features in the Microwave Background,"We report the characterization of bright, compact features in the cosmic
+microwave background radiation (CMBR) detected during the June 1992 and June
+1994 balloon flights of the Medium Scale Anisotropy Measurement (MSAM1-92 and
+MSAM1-94, respectively). Spectral flux densities are determined for each
+feature at 5.7, 9.3, and 16.5 cm$^{-1}$. No viable counterparts for these
+features were found in source catalogs at 5 GHz or at 100 $\mu$m. The measured
+spectrum of each feature is consistent with a temperature fluctuation in the
+CMBR. The existence of these features is consistent with adiabatic fluctuation
+models of anisotropy in the CMBR.",9604155v1
+1996-08-08,Could a Local Group X-Ray Halo Affect the X-Ray and Microwave Backgrounds?,"Suto et al. (1996, astro-ph/9602061 and ApJ, 461, L33) have suggested that an
+X-ray halo in the Local Group might explain both the observed low-energy excess
+in the X-ray background and the quadrupole anisotropy in the cosmic microwave
+background. Recent observations of poor groups of galaxies by the ROSAT PSPC
+set reasonable limits on how extensive and dense such a halo could be. The poor
+groups most similar to the Local Group do not have a detectable halo, and the
+upper limits of these observations suggest that any Local Group halo would be
+nearly two orders of magnitude too tenuous to produce the effects Suto et al.
+(1996) discuss. In particular, the Sunyaev-Zel'dovich effect cannot contribute
+significantly to the quadrupole anisotropy measured by COBE.",9608039v1
+1996-10-21,Testing the effect of geodesic mixing with COBE data to Reveal the Curvature of the Universe,"When considering the statistical properties of a bundle of cosmic microwave
+background (CMB) photons propagating through space, the effect of `mixing
+geodesics' appears with a distinct signature that depends on the geometry of
+space. In a Universe with negative curvature this effect is expected to produce
+elongated anisotropy spots on CMB maps. We used COBE-DMR data to look for such
+effect. Based on the analysis of a measure of eccentricity of hot spots it
+appears that there is a clear indication of an excess eccentricity of hot spots
+with respect to that expected from noise alone. This result must be interpreted
+with caution as this effect can be due in part to galactic emission. If the
+detected eccentricity of anisotropy spots can be attributed to the effect of
+mixing it implies the negative curvature of the Universe and a value of $\Omega
+< 1$.",9610152v1
+1996-11-20,"Microlensing, or Galactic Twinkling","Microlensing has established itself as a powerful new method for the
+detection of baryonic dark matter in the Galaxy. The theory of microlensing is
+sketched and its similarity with the optical effect of twinkling is explained.
+The bulk of the article presents a new analysis of the data-set on microlensing
+towards the Large Magellanic Cloud. The extent, flattening and velocity
+anisotropy of the Galactic halo are unknown. So, it is vital to analyse the
+microlensing data-set with families of models that span the viable ranges of
+these structural parameters. Also crucial is proper modelling of the dark
+matter halo of the Large Magellanic Cloud. Despite all the unknowns, a robust
+conclusion is that the Galactic and LMC haloes cannot be primarily built from
+objects in the mass range 10^{-7} - 0.1 solar masses. The baryonic fraction of
+the Galactic halo probably lies in the range 0.4 - 0.5. The mass of the
+deflectors probably lies between 0.05 - 1.0 solar masses. Stronger claims
+concerning the masses of the dark objects are unwarranted because the estimates
+are sensitive to the uncertain velocity anisotropy.",9611161v1
+1996-11-26,Results from CAT and prospects for the VSA,"We have produced an image of the microwave sky with 30' resolution in a 2
+degree field using the Cosmic Anisotropy Telescope (CAT). Analysis of data
+taken at three frequencies near 15 GHz indicates that most of the signal is due
+to the CMB, with an equivalent broad-band power of Delta T/T = 1.9 +/- 0.5 x
+10^{-5} at angular scales corresponding to multipoles l = 320-500, and Delta
+T/T = 1.8 (+0.7 -0.5) x 10^{-5} at l = 500-680. We are now building a more
+advanced instrument, the Very Small Array (VSA), which will cover the range l =
+130-1800 with a sensitivity per resolution element of Delta T/T ~ 10^{-6}.",9611212v1
+1996-12-11,Peaks in the Cosmic Microwave Background: flat versus open models,"We present properties of the peaks (maxima) of the CMB anisotropies expected
+in flat and open CDM models. We obtain analytical expressions of several
+topological descriptors: mean number of maxima and the probability distribution
+of the gaussian curvature and the eccentricity of the peaks. These quantities
+are calculated as functions of the radiation power spectrum, assuming a
+gaussian distribution of temperature anisotropies. We present results for
+angular resolutions ranging from 5' to 20' (antenna FWHM), scales that are
+relevant for the MAP and COBRAS/SAMBA space missions and the ground-based
+interferometer experiments. Our analysis also includes the effects of noise. We
+find that the number of peaks can discriminate between standard CDM models, and
+that the gaussian curvature distribution provides a useful test for these
+various models, whereas the eccentricity distribution can not distinguish
+between them.",9612114v1
+1997-01-15,Limits to Global Rotation and Shear From the COBE DMR 4-Year Sky Maps,"Small departures from a homogeneous isotropic spacetime create observable
+features in the large-scale anisotropy of the cosmic microwave background. We
+cross-correlate the maps of the cosmic microwave background anisotropy from the
+Cosmic Background Explorer (COBE) Differential Microwave Radiometers (DMR)
+4-year data set with template maps from Bianchi VII_h cosmological models to
+limit global rotation or shear in the early universe. On the largest scales,
+spacetime is well described by the Friedmann-Robertson-Walker metric, with
+departures from isotropy about each spatial point limited to shear sigma/H_0 <
+10^{-9} and rotation omega/H_0 < 6 x 10^{-8} for 0.1 < Omega_0 < 1.",9701090v1
+1997-02-12,Forecasting Cosmic Parameter Errors from Microwave Background Anisotropy Experiments,"Accurate measurements of the cosmic microwave background (CMB) anisotropies
+with an angular resolution of a few arcminutes can be used to determine
+fundamental cosmological parameters such as the densities of baryons, cold and
+hot dark matter, and certain combinations of the cosmological constant and the
+curvature of the Universe to percent-level precision. Assuming the true theory
+is a variant of inflationary cold dark matter cosmologies, we calculate the
+accuracy with which cosmological parameters can be determined by the next
+generation of CMB satellites, MAP and Planck. We pay special attention to: (a)
+the accuracy of the computed derivatives of the CMB power spectrum C_L; (b) the
+number and choices of parameters; (c) the inclusion of prior knowledge of the
+values of various parameters.",9702100v2
+1997-02-23,On classical anisotropies in models of Open Inflation,"In the simplest model of open inflation there are two inflaton fields
+decoupled from each other. One of them, the tunneling field, produces a first
+stage of inflation which prepares the ground for the nucleation of a highly
+symmetric bubble. The other, a free field, drives a second period of slow roll
+inflation inside the bubble. However, the second field also evolves during the
+first stage of inflation, which to some extent breaks the needed symmetry. We
+show that this generates large supercurvature anisotropies which, together with
+the results of Tanaka and Sasaki, rule out this class of simple models (unless,
+of course, $\Omega_0$ is sufficiently close to one.) The problem does not arise
+in modified models where the second field does not evolve in the first stage of
+inflation.",9702201v2
+1997-02-26,The Effect of Weak Gravitational Lensing on the Cosmic Microwave Background Anisotropy: Flat versus Open Universes,"We have studied the effect of gravitational lensing on the Cosmic Microwave
+Background (CMB) anisotropy in flat and open universes. We develop a formalism
+to calculate the changes on the radiation power spectrum induced by lensing in
+the Newtonian and synchronous-comoving gauges. The previously considered
+negligible contribution to the CMB radiation power spectrum of the anisotropic
+term of the lensing correlation is shown to be appreciable. However,
+considering the nonlinear evolution of the matter power spectrum produces only
+slight differences on the results based on linear evolution. The general
+conclusion for flat as well as open universes is that lensing slightly smoothes
+the radiation power spectrum. For a given range of multipoles the effect of
+lensing increases with Omega but for the same acoustic peak it decreases with
+$\Omega$. The maximum contribution of lensing to the radiation power spectrum
+for $l\leq 2000$ is $\sim$ 5% for $\Omega$ values in the range 0.1-1.",9702231v1
+1997-03-28,Inflation: From Theory to Observation and Back,"Alan Guth introduced cosmologists to inflation at the 1980 Texas Symposium.
+Since, inflation has had almost as much impact on cosmology as the big-bang
+model itself. However, unlike the big-bang model, it has little observational
+support. Hopefully, that situation is about to change as a variety and
+abundance of data begin to test inflation in a significant way. The
+observations that are putting inflation to test involve the formation of
+structure in the Universe, especially measurements of the anisotropy of the
+cosmic background radiation. The cold dark matter models of structure formation
+motivated by inflation are holding up well as the observational tests become
+sharper. In the next decade inflation will be tested even more significantly,
+with more precise measurements of CBR anisotropy, the mean density of the
+Universe, the Hubble constant, and the distribution of matter, as well as
+sensitive searches for the nonbaryonic dark matter predicted to exist by
+inflation. As an optimist I believe that we may be well on our way to a
+standard cosmology that includes inflation and extends back to around 10^{-32}
+sec, providing an important window on the earliest moments and fundamental
+physics.",9703194v1
+1997-04-09,Ribbons on the CBR Sky: A Powerful Test of a Baryon Symmetric Universe,"If the Universe consists of domains of matter and antimatter, annihilations
+at domain interfaces leave a distinctive imprint on the Cosmic Background
+Radiation (CBR) sky. The signature is anisotropies in the form of long, thin
+ribbons of width $\theta_W\sim 0.1^\circ$, separated by angle $\theta_L\simeq
+1^\circ(L/100h^{-1}{Mpc})$ where L is the characteristic domain size, and
+y-distortion parameter $y \approx 10^{-6}$. Such a pattern could potentially be
+detected by the high-resolution CBR anisotropy experiments planned for the next
+decade, and such experiments may finally settle the question of whether or not
+our Hubble volume is baryon symmetric.",9704070v2
+1997-08-06,Cosmic Strings in an Open Universe: Quantitative Evolution and Observational Consequences,"The cosmic string scenario in an open universe is developed -- including the
+equations of motion, a model of network evolution, the large angular scale CMB
+temperature anisotropy, and the power spectrum of density fluctuations produced
+by cosmic strings with dark matter. First we derive the equations of motion for
+cosmic string in an open FRW space-time and construct a quantitative model of
+the evolution of the gross features of a cosmic string network. Second, we
+apply this model of network evolution to estimate the rms CMB temperature
+anisotropy induced by cosmic strings, obtaining the normalization for the mass
+per unit length $\mu$ as a function of $\Omega$. Third, we consider the effects
+of the network evolution and normalization in an open universe on the large
+scale structure formation scenarios with either cold or hot dark matter.",9708057v1
+1997-08-13,A built-in scale in the initial spectrum of density perturbations: evidence from cluster and CMB data,"We calculate temperature anisotropies of the cosmic microwave background
+(CMB) for several initial power spectra of density perturbations with a
+built-in scale suggested by recent optical data on the spatial distribution of
+rich clusters of galaxies. Using cosmological models with different values of
+spectral index, baryon fraction, Hubble constant and cosmological constant, we
+compare the calculated radiation power spectrum with the CMB temperature
+anisotropies measured by the Saskatoon experiment. We show that spectra with a
+sharp peak at 120 h^{-1} Mpc are in agreement with the Saskatoon data. The
+combined evidence from cluster and CMB data favours the presence of a peak and
+a subsequent break in the initial matter power spectrum. Such feature is
+similar to the prediction of an inflationary model where an inflaton field is
+evolving through a kink in the potential.",9708128v1
+1997-09-03,On the Problem of Predicting Inflationary Perturbations,"We examine the theoretical foundations of standard methods for computing
+density perturbations in inflationary models. We find that: (1) the time-delay
+formalism (introduced by Guth and Pi, 1982) is only valid when inflation is
+well-described by the de Sitter solution and the equation-of-state is nearly
+unchanging; and, (2) the horizon-crossing/Bessel approximation extends to
+non-exponential inflation, but only if the equation-of-state is changing
+slowly. Integration of the gauge-invariant perturbation equations mode-by-mode
+is the only method reliable for general models. For models with rapidly varying
+equation-of-state, the correction leads to significantly different predictions
+for the microwave background anisotropy. An important corollary is that methods
+proposed for ""reconstruction"" of the inflaton potential from anisotropy data
+are unreliable for general models.",9709032v1
+1997-10-08,CMB anisotropy predictions for a model of double inflation,"We consider a double-inflationary model with two massive scalar fields
+interacting only gravitationally in the context of a flat cold dark matter
+(CDM) Universe. The cosmic microwave background (CMB) temperature anisotropies
+produced in this theory are investigated in great details for a window of
+parameters where the density fluctuation power spectrum P(k) is in good
+agreement with observations. The first Doppler (``acoustic'') peak is a crucial
+test for this model as well as for other models. For the ``standard'' values of
+the cosmological parameters of CDM, our model is excluded if the height of the
+Doppler peak is sensibly higher than about three times the Sachs-Wolfe plateau.",9710083v2
+1997-10-16,Minkowski Functionals used in the Morphological Analysis of Cosmic Microwave Background Anisotropy Maps,"We present a novel approach to quantifying the morphology of Cosmic Microwave
+Background (CMB) anisotropy maps. As morphological descriptors, we use shape
+parameters known as Minkowski functionals. Using the mathematical framework
+provided by the theory of integral geometry on arbitrary curved supports, we
+point out the differences to their characterization and interpretation in the
+case of flat space. With restrictions of real data -- such as pixelization and
+incomplete sky coverage, to mention just a few -- in mind, we derive and test
+unbiased estimators for all Minkowski functionals. Various examples, among them
+the analysis of the four-year COBE DMR data, illustrate the application of our
+method.",9710185v2
+1997-10-30,Circular scans for CMB anisotropy observation and analysis,"A number of experiments for measuring anisotropies of the Cosmic Microwave
+Background use scanning strategies in which temperature fluctuations are
+measured along circular scans on the sky. It is possible, from a large number
+of such intersecting circular scans, to build two-dimensional sky maps for
+subsequent analysis. However, since instrumental effects --- especially the
+excess low-frequency 1/f noise --- project onto such two-dimensional maps in a
+non-trivial way, we discuss the analysis approach which focuses on information
+contained in the individual circular scans. This natural way of looking at CMB
+data from experiments scanning on the circles combines the advantages of
+elegant simplicity of Fourier series for the computation of statistics useful
+for constraining cosmological scenarios,and superior efficiency in analysing
+and quantifying most of the crucial instrumental effects.",9710349v1
+1998-01-24,Structure Formation with Generalized Dark Matter,"The next generation of cosmic microwave background (CMB) experiments, galaxy
+surveys, and high-redshift observations can potentially determine the nature of
+the dark matter observationally. With this in mind, we introduce a
+phenomenological model for a generalized dark matter (GDM) component and
+discuss its effect on large-scale structure and CMB anisotropies. Specifying
+the gravitational influence of the otherwise non-interacting GDM requires not
+merely a model for its equation of state but one for its full stress tensor.
+  From consideration of symmetries, conservation laws, and gauge invariance, we
+construct a simple but powerful 3 component parameterization of these stresses
+that exposes the new phenomena produced by GDM. Limiting cases include: a
+particle component (e.g. WIMPS, radiation or massive neutrinos), a cosmological
+constant, and a scalar field component. Intermediate cases illustrate how the
+clustering properties of the dark matter can be specified independently of its
+equation of state. This freedom allows one to alter the amplitude and features
+in the matter power spectrum relative to those of the CMB anisotropies while
+leaving the background cosmology fixed. Conversely, observational constraints
+on such properties can help determine the nature of the dark matter.",9801234v2
+1998-01-28,Large-Scale Coherent Dipole Anisotropy ?,"We have reanalyzed and compared the dipoles of the 1.2 Jy and 0.6 Jy (QDOT)
+IRAS galaxy samples. We find strong indications from both samples for (a)
+significant contributions to the gravitational field that shapes the Local
+Group motion from depths up to $\sim 170$ $h^{-1}$ Mpc and (b) a large-scale
+coherence of the dipole anisotropy, indications provided mainly by the fact
+that the differential dipoles of large equal volume shells are aligned with the
+CMB dipole and exhibit significant dipole signals. The two IRAS dipoles are
+indistinguishable within 50 $h^{-1}$ Mpc and beyond $\sim 130$ $h^{-1}$ Mpc
+while the QDOT dipole, having a lower flux limit, continues growing with
+respect to the 1.2 Jy sample up to $\sim 100$ $h^{-1}$ Mpc in agreement with
+Rowan-Robinson et al (1990). The most probable cause of these deep dipole
+contributions is the Shapley mass concentration.",9801271v1
+1998-03-21,Evidence for non-Gaussianity in the COBE DMR Four Year Sky Maps,"We introduce and study the distribution of an estimator for the normalized
+bispectrum of the Cosmic Microwave Background (CMB) anisotropy. We use it to
+construct a goodness of fit statistic to test the coadded 53 and 90 GHz
+COBE-DMR 4 year maps for non-Gaussianity. Our results indicate that Gaussianity
+is ruled out at the confidence level in excess of 98%. This value is a lower
+bound, given all the investigated systematics. The dominant non-Gaussian
+contribution is found near the multipole of order $\ell=16$. Our attempts to
+explain this effect as caused by the diffuse foreground emission from the
+Galaxy have failed. We conclude that unless there exists a microwave foreground
+emission which spatially correlates neither with the DIRBE nor Haslam maps, the
+cosmological CMB anisotropy is genuinely non-Gaussian.",9803256v2
+1998-03-23,Microwave Background Signals from Tangled Magnetic Fields,"An inhomogeneous cosmological magnetic field will create Alfven-wave modes
+that induce a small rotational velocity perturbation on the last scattering
+surface of the microwave background radiation. The Alfven-wave mode survives
+Silk damping on much smaller scales than the compressional modes. This, in
+combination with its rotational nature, ensures that there will be no sharp
+cut-off in anisotropy on arc-minute scales. We estimate that a magnetic field
+which redshifts to a present value of $3\times 10^{-9}$ Gauss produces
+temperature anisotropies at the 10 micro Kelvin level at and below 10 arc-min
+scales. A tangled magnetic field, which is large enough to influence the
+formation of large scale structure is therefore potentially detectable by
+future observations.",9803261v1
+1998-05-04,The Impact of Inhomogeneous Reionization on Cosmic Microwave Background Anisotropy,"Hydrogen atoms in the Universe that initially formed at redshift z = 1100
+were reionized at 5 < z < 60. It is likely that this transition proceeded
+through a mixed phase of partial ionization. We develop an analytic approach to
+calculating the effect on the cosmic microwave background (CMB) of Thomson
+scattering off this inhomogeneous distribution of free electrons. We study two
+models of the reionization process, one of which associates ionized patches
+with overdense regions of the smoothed density field. We find the generated
+anisotropy to have a power spectrum which peaks at angular scales corresponding
+to the extent of the ionized regions, and has a width that reflects the
+correlations between them. There is considerable uncertainty in the amplitude,
+which depends on how efficiently collapsed objects can reionize the surrounding
+medium. We calculate the effect of neglecting inhomogeneous reionization in the
+determination of cosmological parameters from high resolution CMB maps and find
+that it may be a significant source of systematic error.",9805012v2
+1998-05-19,Australia Telescope Search for Cosmic Microwave Background Anisotropy,"We have made an 8.7 GHz image of a sky region with a resolution of 8 arcmin
+and high brightness sensitivity using the Australia Telescope Compact Array
+(ATCA). in an ultra compact configuration. The foreground discrete-source
+confusion was estimated from observations with higher resolution at the same
+frequency and in a scaled array at a lower frequency. Following the subtraction
+of the foreground confusion, the field shows no features in excess of the
+instrument noise. This limits the CMB anisotropy flat-band power to Q_flat <
+23.6 microK with 95 per cent confidence; the ATCA filter function F_l in
+multipole l-space peaks at l_eff = 4700 and has half maximum values at l = 3350
+and 6050.",9805245v1
+1998-05-22,Gravitational lensing of cosmic microwave background anisotropies and cosmological parameter estimation,"Gravitational lensing, caused by matter perturbations along the line-of-sight
+to the last scattering surface, can modify the shape of the cosmic microwave
+background (CMB) anisotropy power spectrum. We discuss the detectability of
+lensing distortions to the temperature, polarisation and
+temperature-polarisation cross-correlation power spectra and we analyse how
+lensing might affect the estimation of cosmological parameters. For cold dark
+matter-like models with present-day matter power spectra normalised to match
+the abundances of rich clusters of galaxies, gravitational lensing causes
+detectable distortions to cosmic variance limited CMB experiments sampling high
+multipoles (l > 1000). Gravitational lensing of the CMB, although a small
+effect, allows independent determinations of the curvature of the universe and
+the cosmological constant, i.e. breaking the so-called geometrical degeneracy
+in CMB parameter estimation discussed by Bond, Efstathiou and Tegmark (1997)
+and Zaldarriaga, Spergel and Seljak (1997). Gravitational lensing of the CMB
+temperature and polarisation patterns should be detectable by the Planck
+Surveyor satellite leading to useful independent constraints on the
+cosmological constant and spatial curvature.",9805294v2
+1998-06-08,Cosmic strings in a universe with non-critical matter density,"In the light of recent work which suggests that structure formation by cosmic
+strings in a critical matter density universe requires large biases, we discuss
+the effects of reducing the matter density. Using a full linear
+Einstein-Boltzmann solver, we com pute the cold dark matter density field and
+the microwave background anisotropies/polarization in a flat universe with a
+non-zero cosmological constant. We find that universes with
+$\Omega_{\Lambda}=0.7-0.8$ give a good fit to the shape of the observed ga laxy
+distribution, albeit with a bias of around 2. This has interesting implications
+for the anisotropy and polarization of the microwave background. Finally, we
+discuss the effects of relaxing the assumption that the universe is flat.",9806115v1
+1998-06-08,Probing Unstable Massive Neutrinos with Current Cosmic Microwave Background Observations,"The pattern of anisotropies in the Cosmic Microwave Background depends upon
+the masses and lifetimes of the three neutrino species. A neutrino species of
+mass greater than 10 eV with lifetime between 10^{13} sec and 10^{17} sec
+leaves a very distinct signature (due to the integrated Sachs-Wolfe effect):
+the anisotropies at large angles are predicted to be comparable to those on
+degree scales. Present data exclude such a possibility and hence this region of
+parameter space. For $m_\nu \simeq 30$ eV, $\tau \simeq 10^{13}$ sec, we find
+an interesting possibility: the Integrated Sachs Wolfe peak produced by the
+decaying neutrino in low-$\Omega$ models mimics the acoustic peak expected in
+an $\Omega = 1$ model.",9806116v1
+1998-07-10,Cosmic Confusion: Degeneracies among Cosmological Parameters Derived from Measurements of Microwave Background Anisotropies,"In the near future, observations of the cosmic microwave background (CMB)
+anisotropies will provide accurate determinations of many fundamental
+cosmological parameters. In this paper, we analyse degeneracies among
+cosmological parameters to illustrate some of the limitations inherent in CMB
+parameter estimation. For simplicity, throughout our analysis we assume a cold
+dark matter universe with power-law adiabatic scalar and tensor fluctuation
+spectra. We show that most of the variance in cosmological parameter estimates
+is contributed by a small number (two or three) principal components. An exact
+likelihood analysis shows that the usual Fisher matrix approach can
+significantly overestimate the errors on cosmological parameters. We show that
+small correlated errors in estimates of the CMB power spectrum at levels well
+below the cosmic variance limits, (caused, for example, by Galactic foregrounds
+or scanning errors) can lead to significant biases in cosmological parameters.
+Estimates of cosmological parameters can be improved very significantly by
+applying theoretical restrictions to the tensor component and external
+constraints derived from more conventional astronomical observations such as
+measurements of he Hubble constant, Type 1a supernovae distances and
+observations of galaxy clustering and peculiar velocities.",9807103v1
+1998-08-06,Mapping the CMB I: the first flight of the QMAP experiment,"We report on the first flight of the balloon-borne QMAP experiment. The
+experiment is designed to make a map of the cosmic microwave background
+anisotropy on angular scales from 0.7 to several degrees. Using the map we
+determine the angular power spectrum of the anisotropy in multipole bands from
+l~40 to l~140. The results are consistent with the Saskatoon (SK) measurements.
+The frequency spectral index (measured at low l) is consistent with that of CMB
+and inconsistent with either Galactic synchrotron or free-free emission. The
+instrument, measurement, analysis of the angular power spectrum, and possible
+systematic errors are discussed.",9808043v1
+1998-08-11,No Pulsar Kicks from Deformed Neutrinospheres,"In a supernova core, magnetic fields cause a directional variation of the
+neutrino refractive index so that resonant flavor oscillations would lead to a
+deformation of the ""neutrinosphere"" for, say, tau neutrinos. The associated
+anisotropic neutrino emission was proposed as a possible origin of the observed
+pulsar proper motions. We argue that this effect was vastly overestimated
+because the variation of the temperature over the deformed neutrinosphere is
+not an adequate measure for the anisotropy of neutrino emission. The neutrino
+flux is generated inside the neutron star core and is transported through the
+atmosphere at a constant luminosity, forcing the temperature gradient in the
+atmosphere to adjust to the inflow of energy from below. Therefore, no emission
+anisotropy is caused by a deformation of the neutrinosphere to lowest order. An
+estimate of the higher-order corrections must take into account the modified
+atmospheric temperature profile in response to the deformation of the
+neutrinosphere and the corresponding feedback on the core. We go through this
+exercise in the framework of a simplified model which can be solved
+analytically.",9808099v2
+1998-09-24,The Cosmic Microwave Background: Beyond the Power Spectrum,"Much recent work on the cosmic microwave background (CMB) has focussed on the
+angular power spectrum of temperature anisotropies and particularly on the
+recovery of cosmological parameters from acoustic peaks in the power spectrum.
+However, there is more that can conceivably be done with CMB measurements. Here
+I briefly survey a few such ideas: cross-correlation with other cosmic
+backgrounds as a probe of the density of the Universe; CMB polarization as a
+gravitational-wave detector; secondary anisotropies and the ionization history
+of the Universe; tests of alternative-gravity theories; polarization, the
+Sunyaev-Zeldovich effect, and cosmic variance; and tests for a neutrino mass.",9809320v1
+1998-10-02,Computation of eigenmodes on a compact hyperbolic 3-space,"Measurements of cosmic microwave background (CMB) anisotropy are ideal
+experiments for discovering the non-trivial global topology of the universe. To
+evaluate the CMB anisotropy in multiply-connected compact cosmological models,
+one needs to compute the eigenmodes of the Laplace-Beltrami operator. Using the
+direct boundary element method, we numerically obtain the low-lying eigenmodes
+on a compact hyperbolic 3-space called the Thurston manifold which is the
+second smallest in the known compact hyperbolic 3-manifolds. The computed
+eigenmodes are expanded in terms of eigenmodes on the unit three-dimensional
+pseudosphere. We numerically find that the expansion coefficients behave as
+Gaussian pseudo-random numbers for low-lying eigenmodes. The observed
+gaussianity in the CMB fluctuations can partially be attributed to the Gaussian
+pseudo-randomness of the expansion coefficients assuming that the Gaussian
+pseudo-randomness is the universal property of the compact hyperbolic spaces.",9810034v3
+1998-10-08,Microwave Background Anisotropies and Nonlinear Structures I. Improved Theoretical Models,"A new method is proposed for modelling spherically symmetric inhomogeneities
+in the Universe. The inhomogeneities have finite size and are compensated, so
+they do not exert any measurable gravitational force beyond their boundary. The
+region exterior to the perturbation is represented by a
+Friedmann-Robertson-Walker (FRW) Universe, which we use to study the anisotropy
+in the cosmic microwave background (CMB) induced by the cluster. All
+calculations are performed in a single, global coordinate system, with
+nonlinear gravitational effects fully incorporated. An advantage of the gauge
+choices employed here is that the resultant equations are essentially Newtonian
+in form. Examination of the problem of specifying initial data shows that the
+new model presented here has many advantages over `Swiss cheese' and other
+models. Numerical implementation of the equations derived here is described in
+a subsequent paper.",9810123v1
+1998-10-09,Microwave background anisotropies and non-linear structures II. Numerical computations,"A new method for modelling spherically symmetric inhomogeneities is applied
+to the formation of clusters in an expanding Universe. We impose simple initial
+velocity and density perturbations of finite extent and we investigate the
+subsequent evolution of the density field. Photon paths are also calculated,
+allowing a detailed consideration of gravitational lensing effects and
+microwave background anisotropies induced by the cluster. We apply the method
+to modelling high-redshift clusters and, in particular, we consider the
+reported microwave decrement observed towards the quasar pair PC1643+4631 A&B.
+We also consider the effect on the primordial microwave background power
+spectrum due to gravitational lensing by a population of massive high-redshift
+clusters.",9810149v1
+1998-10-20,Cosmic microwave background anisotropies seeded by coherent topological defects : a semi-analytic approach,"We consider a perfectly homogeneous, isotropic and spatially flat universe
+which undergoes a sudden phase transition producing topological defects. We
+assume that these defects form a coherent network which scales like the
+background density during the radiation and matter dominated eras, and describe
+them in terms of a few free functions. We carefully model the loss of scaling
+invariance during the transition from radiation to matter dominated era. We
+choose a simple set for the free functions, compute the microwave background
+temperature anisotropies generated by such a network, and compare our results
+to previous calculations.",9810313v2
+1998-12-11,Constraints on Omega_Lambda and Omega_m from Distant Type 1a Supernovae and Cosmic Microwave Background Anisotropies,"We perform a combined likelihood analysis of the latest cosmic microwave
+background anisotropy data and distant Type 1a Supernova data of Perlmutter
+etal (1998a). Our analysis is restricted to cosmological models where structure
+forms from adiabatic initial fluctuations characterised by a power-law spectrum
+with negligible tensor component. Marginalizing over other parameters, our best
+fit solution gives Omega_m = 0.25 (+0.18, -0.12) and Omega_Lambda = 0.63
+(+0.17, -0.23) (95 % confidence errors) for the cosmic densities contributed by
+matter and a cosmological constant respectively. The results therefore strongly
+favour a nearly spatially flat Universe with a non-zero cosmological constant.",9812226v1
+1998-12-15,Model-Independent Measurement of the Primordial Power Spectrum,"In inflationary models with minimal amount of gravity waves, the primordial
+power spectrum of density fluctuations, $A_S^2(k)$, together with the basic
+cosmological parameters, completely specify the predictions for the cosmic
+microwave background (CMB) anisotropy and large scale structure. Here we show
+how we can strongly constrain both $A_S^2(k)$ and the cosmological parameters
+by combining the data from the Microwave Anisotropy Probe (MAP) and the galaxy
+redshift survey from the Sloan Digital Sky Survey (SDSS). We allow $A_S^2(k)$
+to be a free function, and thus probe features in the primordial power spectrum
+on all scales. MAP and SDSS have scale-dependent measurement errors that
+decrease in opposite directions on astrophysically interesting scales; they
+complement each other and allow the measurement of the primordial power
+spectrum independent of inflationary models, giving us valuable information on
+physics in the early Universe, and providing clues to the correct inflationary
+model.",9812291v1
+1999-01-04,"CMB Anisotropy Constraints on Open and Flat-Lambda CDM Cosmogonies from UCSB South Pole, ARGO, MAX, White Dish, and SuZIE Data","We use combinations of ten small-scale cosmic microwave background anisotropy
+data sets from the UCSB South Pole 1994, ARGO, MAX 4 and 5, White Dish and
+SuZIE experiments to constrain cosmogonies. We consider open and
+spatially-flat-Lambda cold dark matter cosmogonies. Marginalizing over all
+parameters but $\Omega_0$, the combined data favors an Omega_0 simeq 1 for both
+open and flat-Lambda models. Excluding the smallest angular scale SuZIE data,
+an Omega_0 simeq 0.3 (1.0) open (flat-Lambda) model is favored. Considering
+only multi-frequency data with error bars consistent with sample variance and
+noise considerations, an Omega_0 simeq 0.1 (1) open (flat-Lambda) model is
+favored. For both open and flat-$\Lambda$ models, after marginalizing over all
+the other parameters, a lower Omega_B h^2 (sim 0.005) or younger (t_0 sim 10
+Gyr) universe is favored. However, the data do not rule out other values of
+Omega_0 in the flat-Lambda model and other values of Omega_B h^2 in both
+models. (abriged)",9901014v1
+1999-01-05,Limits on the gravity wave contribution to microwave anisotropies,"We present limits on the fraction of large angle microwave anisotropies which
+could come from tensor perturbations. We use the COBE results as well as
+smaller scale CMB observations, measurements of galaxy correlations, abundances
+of galaxy clusters, and Lyman alpha absorption cloud statistics. Our aim is to
+provide conservative limits on the tensor-to-scalar ratio for standard
+inflationary models. For power-law inflation, for example, we find T/S<0.52 at
+95% confidence, with a similar constraint for phi^p potentials. However, for
+models with tensor amplitude unrelated to the scalar spectral index it is still
+currently possible to have T/S>1.",9901028v2
+1999-01-12,Observation of the east-west anisotropy of the atmospheric neutrino flux,"The east-west anisotropy, caused by the deflection of primary cosmic rays in
+the Earth's magnetic field, is observed for the first time in the flux of
+atmospheric neutrinos. Using a 45 kt-year exposure of the
+  Super-Kamiokande detector, 552 e-like and 633 mu-like horizontally-going
+events are selected in the momentum range between 400 and 3000 MeV/c.
+  The azimuthal distribution of e-like and mu-like events agrees with the
+expectation from atmospheric neutrino flux calculations that account for the
+geomagnetic field, verifying that the geomagnetic field effects in the
+production of atmospheric neutrinos in the GeV energy range are well
+understood.",9901139v1
+1999-01-27,Cosmic Microwave Background Anisotropies from Global Texture,"We investigate the global texture model of structure formation in cosmogonies
+with non-zero cosmological constant for different values of the Hubble
+parameter. We find that the absence of significant acoustic peaks and little
+power on large scales are robust predictions of these models. However, from a
+careful comparison with experiments we conclude that at present we cannot
+safely reject the model on the grounds of published CMB anisotropy data.
+  If bias is close to one on large scales, galaxy correlation data rules out
+the models. New, very stringent constraints come from peculiar velocities.
+  Investigating the large-N limit, we argue that our main conclusions apply to
+all global O(N) models of structure formation.",9901377v1
+1999-02-03,New CMB Power Spectrum Constraints from MSAMI,"We present new cosmic microwave background (CMB) anisotropy results from the
+combined analysis of the three flights of the first Medium Scale Anisotropy
+Measurement (MSAM1). This balloon-borne bolometric instrument measured about 10
+square degrees of sky at half-degree resolution in 4 frequency bands from 5.2
+icm to 20 icm with a high signal-to-noise ratio. Here we present an overview of
+our analysis methods, compare the results from the three flights, derive new
+constraints on the CMB power spectrum from the combined data and reduce the
+data to total-power Wiener-filtered maps of the CMB. A key feature of this new
+analysis is a determination of the amplitude of CMB fluctuations at $\ell \sim
+400$. The analysis technique is described in a companion paper by Knox.",9902047v1
+1999-02-22,Reionization of the Intergalactic Medium and its Effect on the CMB,"The bulk of the hydrogen in the universe transformed from neutral to ionized
+somewhere in the redshift interval 5 < z < 40, most likely due to ionizing
+photons produced by an early generation of stars or mini-quasars. The resulting
+free electrons, interacting with the CMB photons via Thomson scattering, are a
+mixed blessing, providing both a probe of the epoch of the first stars and a
+contaminant to the pristine primary anisotropy. Here we review our current
+knowledge of reionization with emphasis on inhomogeneities and describe the
+possible connections to CMB anisotropy.",9902311v2
+1999-03-05,Stability of rotating spherical stellar systems,"We study the stability of rotating collisionless self-gravitating spherical
+systems by using high resolution N-body experiments on a Connection Machine
+CM-5. We added rotation to Ossipkov-Merritt (hereafter OM) anisotropic
+spherical systems by using two methods. The first method conserves the
+anisotropy of the distribution function defined in the OM algorithm. The second
+method distorts the systems in velocity space. We then show that the stability
+of systems depends both on their anisotropy and on the value of the ratio
+between the total kinetic energy and the rotational kinetic energy. We also
+test the relevance of the stability parameters introduced by Perez et al.
+(1996) for the case of rotating systems.",9903087v1
+1999-03-09,Supercluster Magnetic Fields and Anisotropy of Cosmic Rays above 10**(19) eV,"We predict energy spectra and angular distributions of nucleons above
+10**(19) eV that originate from sources distributed in the Local Supercluster,
+which is also supposed to contain a large scale magnetic field of strength
+between 0.05 and 0.5 micro Gauss. We show that this model can explain all
+present-day features of ultra-high energy cosmic rays, at least for field
+strengths close to 0.5 micro Gauss. The large-scale anisotropy and the
+clustering predicted by this scenario will allow strong discrimination against
+other models with next generation experiments.",9903124v1
+1999-03-09,On Planck simulations: towards `2-nd order' analyses,"We simulate Planck observations by adopting a detailed model of the microwave
+sky including monopole, dipole, anisotropies of the cosmic microwave background
+(CMB) and galactic and extragalactic foregrounds. We estimate the impact of
+main beam optical aberrations on CMB anisotropy measurements in presence of
+extragalactic source fluctuations and we discuss the main implications for the
+Planck telescope design. By analysing the dipole pattern, we quantify the
+Planck performance in the determination of CMB spectral distortion parameters
+in presence of foreground contaminations.",9903137v1
+1999-03-11,Dark matter halos and the anisotropy of ultra-high energy cosmic rays,"Several explanations for the existence of Ultra High Energy Cosmic Rays
+invoke the idea that they originate from the decay of massive particles created
+in the reheating following inflation. It has been suggested that the decay
+products can explain the observed isotropic flux of cosmic rays. We have
+calculated the anisotropy expected for various models of the dark matter
+distribution and find that at present data are too sparse above $4 \times
+10^{19}$ eV to discriminate between different models. However we show that with
+data from three years of operation of the southern section of the Pierre Auger
+Observatory significant progress in testing the proposals will be made.",9903182v1
+1999-03-18,The covariant perturbative approach to cosmic microwave background anisotropies,"The Ehlers-Ellis 1+3 formulation of covariant hydrodynamics, when
+supplemented with covariant radiative transport theory, gives an exact,
+physically transparent description of the physics of the cosmic microwave
+background radiation (CMB). Linearisation around a Friedmann-Robertson-Walker
+(FRW) universe provides a very direct and seamless route through to the linear,
+gauge-invariant perturbation equations for scalar, vector and tensor modes in
+an almost-FRW model. In this contribution we review covariant radiative
+transport theory and its application to the perturbative method for calculating
+and understanding the anisotropy of the CMB. Particular emphasis is placed on
+the inclusion of polarization in a fully covariant manner. With this inclusion,
+the covariant perturbative approach offers a complete description of linearised
+CMB physics in an almost-FRW universe.",9903283v1
+1999-04-18,Gravity waves goodbye,"The detection of a stochastic background of long-wavelength gravitational
+waves (tensors) in the cosmic microwave background (CMB) anisotropy would be an
+invaluable probe of the high energy physics of the early universe.
+Unfortunately a combination of factors now makes such a detection seem
+unlikely: the vast majority of the CMB signal appears to come from density
+perturbations (scalars) - detailed fits to current observations indicate a
+tensor-to-scalar quadrupole ratio of T/S < 0.5 for the simplest models; and on
+the theoretical side the best-motivated inflationary models seem to require
+very small T/S. Unfortunately CMB temperature anisotropies can only probe a
+gravity wave signal down to T/S \sim 10% and optimistic assumptions about
+polarization of the CMB only lower this another order of magnitude.",9904228v1
+1999-05-08,A Measurement of the Angular Power Spectrum of the Microwave Background Made from the High Chilean Andes,"We report on a measurement of the angular spectrum of the anisotropy of the
+microwave sky at 30 and 40 GHz between l=50 and l=200 over approximately 600
+sq. deg. The data support a rise in the angular spectrum to a maximum with
+$\delta T_l \approx 85 \mu$K at l=200. We also give a 2-sigma upper limit of
+$\delta T_l < 122 \mu$K at l=432 at 144 GHz. These results come from the first
+campaign of the Mobile Anisotropy Telescope (MAT) on Cerro Toco, Chile. To
+assist in assessing the site, we present plots of the fluctuations in
+atmospheric emission at 30 and 144 GHz.",9905100v3
+1999-05-11,"Python I, II, and III CMB Anisotropy Measurement Constraints on Open and Flat-Lambda CDM Cosmogonies","We use Python I, II, and III cosmic microwave background anisotropy data to
+constrain cosmogonies. We account for the Python beamwidth and calibration
+uncertainties. We consider open and spatially-flat-Lambda cold dark matter
+cosmogonies, with nonrelativistic-mass density parameter Omega_0 in the range
+0.1--1, baryonic-mass density parameter Omega_B in the range (0.005--0.029)
+h^{-2}, and age of the universe t_0 in the range (10--20) Gyr. Marginalizing
+over all parameters but Omega_0, the combined Python data favors an open
+(spatially-flat-Lambda) model with Omega_0 simeq 0.2 (0.1). At the 2 sigma
+confidence level model normalizations deduced from the combined Python data are
+mostly consistent with those drawn from the DMR, UCSB South Pole 1994, ARGO,
+MAX 4 and 5, White Dish, and SuZIE data sets.",9905127v1
+1999-05-19,UHECR Anisotropy and the Galactic Halo,"Several explanations for the existence of Ultra High Energy Cosmic Rays
+(UHECR) invoke the idea that they originate from the decay of massive particles
+created in the reheating following inflation. It has been suggested that the
+decay products can explain the observed isotropic flux of UHECR. We have
+calculated the anisotropy expected for various models of the dark matter
+distribution and find that present data are too sparse above 4 x 10^19 eV to
+discriminate between different models. However, after three years of operation
+of the southern part of the Pierre Auger Observatory great progress in testing
+the proposals is expected.",9905240v1
+1999-05-20,Lensing-Induced Structure of Submillimeter Sources: Implications for the Microwave Background,"We consider the effect of lensing by galaxy clusters on the angular
+distribution of submillimeter wavelength objects. While lensing does not change
+the total flux and number counts of submillimeter sources, it can affect the
+number counts and fluxes of flux-limited samples. Therefore imposing a flux cut
+on point sources not only reduces the overall Poisson noise, but imprints the
+correlations between lensing clusters on the unresolved flux distribution.
+Using a simple model, we quantify the lensing anisotropy induced in
+flux-limited samples and compare this to Poisson noise. We find that while the
+level of induced anisotropies on the scale of the cluster angular correlation
+length is comparable to Poisson noise for a slowly evolving cluster model, it
+is negligible for more realistic models of cluster evolution. Thus the removal
+of point sources is not expected to induce measurable structure in the
+microwave or far-infrared backgrounds.",9905269v1
+1999-05-26,Cosmic Microwave Background anisotropies and extra dimensions in String Cosmology,"A recently proposed mechanism for large-scale structure in string cosmology
+--based on massless axionic seeds-- is further analyzed and extended to the
+acoustic-peak region. Existence, structure, and normalization of the peaks turn
+out to depend crucially on the overall evolution of extra dimensions during the
+pre-big bang phase: conversely, precise cosmic microwave background anisotropy
+data in the acoustic-peak region will provide, within the next decade, a window
+on string-theory's extra dimensions before their eventual compactification.",9905327v3
+1999-06-22,The roughness of the last scattering surface,"We propose an alternative analysis of the microwave background temperature
+anisotropy maps that is based on the study of the roughness of natural
+surfaces. We apply it to large angle anisotropies, such as those measured by
+COBE-DMR. We show that for a large signal to noise experiment, the spectral
+index can be determined independently of the normalization. We then analyze the
+4 yr COBE map and find for a flat $\Omega=1$ universe, that the best-fitting
+value for the spectral index is $n = 1.15^{+0.39}_{-0.34}$ and for the
+amplitude $Q_{rms-PS}= 14.1^{+3.9}_{-3.5}\mu K$. For $n=1$, the best-fitting
+normalization is $Q_{rms-PS}|_{n=1}= 16.2^{+1.4}_{-1.3}\mu K$.",9906345v1
+1999-06-29,Microwave background anisotropies from gravitational waves: the 1+3 covariant approach,"We present a 1+3 covariant discussion of the contribution of gravitational
+waves to the anisotropy of the CMB in an almost-Friedmann-Robertson-Walker
+universe. Our discussion is based in the covariant approach to perturbations in
+cosmology, which provides a physically transparent and gauge-invariant
+methodology for CMB physics. Applying this approach to linearised gravitational
+waves, we derive a closed set of covariant equations describing the evolution
+of the shear and the Weyl tensor, and the angular multipoles of the CMB
+intensity, valid for an arbitrary matter description and background spatial
+curvature. A significant feature of the present approach is that the normal
+mode expansion of the radiation distribution function, which arises naturally
+here, preserves the simple quadrupolar nature of the anisotropic part of the
+Thomson scattering source terms, and provides a direct characterisation of the
+power in the CMB at a given angular multipole, as in the recently introduced
+total angular momentum method. We provide the integral solution of the
+multipole equations, and analytic solutions for the shear and the Weyl tensor,
+for models with arbitrary spatial curvature. Numerical results for the CMB
+power spectrum in open models are also presented.",9906474v2
+1999-07-15,An Observational Test of Quantum Cosmology,"We compute the tensor CMB anisotropy power spectrum for singular and
+non-singular instantons describing the beginning of an open universe according
+to the Euclidean no boundary proposal. Singular instantons occur generically,
+whereas non-singular instantons require more contrived scalar field potentials.
+For the latter, we consider potentials in which a sharp feature, either
+negative or positive, is added to a gently sloping potential. In the first case
+one finds a nearly divergent contribution to the low multipole CMB anisotropy,
+in conflict with the COBE observations. In the second case the divergence is
+weaker, but matching the low multipoles forces the added feature to be large
+and narrow. For singular instantons, there is a better match to the
+observations, without any such contrivance. The distinction between singular
+and nonsingular instantons disappears in the limit as the universe becomes
+flat, but is still observable for densities as high as 0.7 of the critical
+density.",9907212v2
+1999-09-04,Constraints on structure formation models from Sunyaev-Zel'dovich Effect,"In the context of cold dark matter (CDM) cosmological models, we have
+simulated images of the brightness temperature fluctuations in the cosmic
+microwave background (CMB)sky owing to the Sunyaev Zel$^{\prime}$dovich (S-Z)
+effect in a cosmological distribution of clusters. We compare the image
+statistics with recent ATCA limits on arcmin-scale CMB anisotropy. The S-Z
+effect produces a generically non-Gaussian field and we compute the variance in
+the simulated temperature-anisotropy images, after convolution with the ATCA
+beam pattern, for different cosmological models. All the models are normalised
+to the 4-year {\it COBE} data. We find an increase in the simulated-sky
+temperature variance with increase in the cosmological density parameter
+$\Omega_0$. A comparison with the upper limits on the sky variance set by the
+ATCA appears to rule out our closed-universe model: low-$\Omega_0$
+open-universe models are preferred. The result is independent of any present
+day observations of $\sigma_8$.",9909087v1
+1999-09-07,Anisotropies of Cosmic Rays and Search for Intergalactic Cascades from the direction of the Highest Energetic Cosmic Ray Events with the HEGRA Scintillator Array,"Data taken with the HEGRA Scintillator Array have been used to search for
+spatial anisotropies in the arrival directions of cosmic rays above 20 TeV. In
+this paper results on the search for TeV gamma-ray emission from the Galactic
+plane and the Gould belt are presented. Furthermore, a search for TeV gamma-ray
+emission correlated with the arrival directions of cosmic rays with energies
+well beyond the Greizen-Zatsepin-Kuzmin cutoff has been performed. Such a
+correlation can be expected from sufficiently high energetic nuclei inducing
+electromagnetic cascades on the diffuse intergalactic background radiation,
+eventually producing TeV photons. Interestingly, the direction of the most
+energetic event yields the highest excess with a chance probability of 1.8%.",9909125v1
+1999-09-29,Analysis of CMB maps with 2D wavelets,"We consider the 2D wavelet transform with two scales to study sky maps of
+temperature anisotropies in the cosmic microwave background radiation (CMB). We
+apply this technique to simulated maps of small sky patches of size 12.8 \times
+12.8 square degrees and 1.5' \times 1.5' pixels. The relation to the standard
+approach, based on the cl's is established through the introduction of the
+scalogram. We consider temperature fluctuations derived from standard, open and
+flat-Lambda CDM models. We analyze CMB anisotropies maps plus uncorrelated
+Gaussian noise (uniform and non-uniform) at idfferent S/N levels. We explore in
+detail the denoising of such maps and compare the results with other techniques
+already proposed in the literature. Wavelet methods provide a good
+reconstruction of the image and power spectrum. Moreover, they are faster than
+previously proposed methods.",9909497v1
+1999-10-27,Lensing of the CMB: Non Gaussian aspects,"We study the generation of CMB anisotropies by gravitational lensing on small
+angular scales. We show these fluctuations are not Gaussian. We prove that the
+power spectrum of the tail of the CMB anisotropies on small angular scales
+directly gives the power spectrum of the deflection angle. We show that the
+generated power on small scales is correlated with the large scale gradient.
+The cross correlation between large scale gradient and small scale power can be
+used to test the hypothesis that the extra power is indeed generated by
+lensing. We compute the three and four point function of the temperature in the
+small angle limit. We relate the non-Gaussian aspects presented in this paper
+as well as those in our previous studies of the lensing effects on large scales
+to the three and four point functions. We interpret the statistics proposed in
+terms of different configurations of the four point function and show how they
+relate to the statistic that maximizes the S/N.",9910498v2
+1999-11-03,Tensor Microwave Anisotropies from a Stochastic Magnetic Field,"We derive an expression for the angular power spectrum of cosmic microwave
+background anisotropies due to gravity waves generated by a stochastic magnetic
+field and compare the result with current observations; we take into account
+the non-linear nature of the stress energy tensor of the magnetic field.
+  For almost scale invariant spectra, the amplitude of the magnetic field at
+galactic scales is constrained to be of order 10^{-9} Gauss. If we assume that
+the magnetic field is damped below the Alfven damping scale, we find that its
+amplitude at
+  0.1 h^{-1}Mpc, B_\lambda, is constrained to be B_\lambda<7.9 x10^{-6} e^{3n}
+Gauss, for n<-3/2, and B_\lambda<9.5x10^{-8} e^{0.37n} Gauss, for n>-3/2, where
+n is the spectral index of the magnetic field and H_0=100h km s^{-1}Mpc^{-1} is
+the Hubble constant today.",9911040v1
+1999-11-19,MADCAP - The Microwave Anisotropy Dataset Computational Analysis Package,"Realizing the extraordinary scientific potential of the CMB requires precise
+measurements of its tiny anisotropies over a significant fraction of the sky at
+very high resolution. The analysis of the resulting datasets is a serious
+computational challenge. Existing algorithms require terabytes of memory and
+hundreds of years of CPU time. We must therefore both maximize our resources by
+moving to supercomputers and minimize our requirements by algorithmic
+development. Here we will outline the nature of the challenge, present our
+current optimal algorithm, and discuss its implementation as the MADCAP
+software package and application to data from the North American test flight of
+the joint Italian-U.S. BOOMERanG experiment on the Cray T3E at NERSC and
+CINECA.
+  A documented beta-release of MADCAP is publicly available at
+http://cfpa.berkeley.edu/~borrill/cmb/madcap.html",9911389v1
+1999-11-22,Data Reduction and Analysis of the Python V Cosmic Microwave Background Anisotropy Experiment,"Observations of the microwave sky using the Python telescope in its fifth
+season of operation at the Amundsen-Scott South Pole Station in Antarctica are
+presented. The system consists of a 0.75 m off-axis telescope instrumented with
+a HEMT amplifier-based radiometer having continuum sensitivity from 37-45 GHz
+in two frequency bands. With a $0.91^{\circ} \times 1.02^{\circ} $ beam the
+instrument fully sampled 598 deg$^2$ of sky, including fields measured during
+the previous four seasons of Python observations. Interpreting the observed
+fluctuations as anisotropy in the cosmic microwave background, we place
+constraints on the angular power spectrum of fluctuations in eight multipole
+bands up to $l \sim 260$. The observed spectrum is consistent with both the
+COBE experiment and previous Python results. Total-power Wiener-filtered maps
+of the CMB are also presented. There is no significant contamination from known
+foregrounds. The results show a discernible rise in the angular power spectrum
+from large ($l \sim 40$) to small ($l \sim 200$) angular scales.",9911419v1
+1999-12-03,The mildly nonlinear imprint of structure on the CMB,"I outline some nonperturbative relativistic effects that arise from
+gravitational corrections to the Boltzmann equations. These may be important
+for the study of CMB temperature anisotropies, particularly their
+interpretation. These terms are not included in the canonical treatment as they
+arise from the exact equations. Here a weakly nonlinear investigation of these
+effects is defined and investigated with an emphasis on a Rees-Sciama sourced
+effect -- the imprint of structure evolution on the CMB. It is shown that
+gravitational nonlinearity in the weakly nonlinear extension of almost-FLRW
+temperature anisotropies leads to cancellation on small-scales when threading
+in the Newtonian frame. In the general frame this cancellation does not occur.
+In the context of a flat almost-FLRW CDM model I provide a heuristic argument
+for a nonperturbative small scale correction, due to the Rees-Sciama effect, of
+not more than $\Delta T/T \sim 10^{-6}-10^{-5}$ near $\ell \sim 100 - 300$. The
+effect of mild gravitational nonlinearity could be more sophisticated than
+previously expected.",9912072v2
+2000-01-14,Electron Firehose instability and acceleration of electrons in solar flares,"An electron distribution with a temperature anisotropy T_par/T_perp > 1 can
+lead to the Electron Firehose instability (Here par and perp denote directions
+relative to the background magnetic field B_0). Since possible particle
+acceleration mechanisms in solar flares exhibit a preference of energizing
+particles in parallel direction, such an anisotropy is expected during the
+impulsive phase of a flare. The properties of the excited waves and the
+thresholds for instability are investigated by using linearized kinetic theory.
+These thresholds were connected to the pre-flare plasma parameters by assuming
+an acceleration model acting exclusively in parallel direction. For usually
+assumed pre-flare plasma conditions the electrons become unstable during the
+acceleration process and lefthand circularly polarized waves with frequencies
+of about the proton gyrofrequency are excited at parallel propagation.
+Indications have been found, that the largest growth rates occur at oblique
+propagation and the according frequencies lie well above the proton
+gyrofrequency.",0001262v1
+2000-01-18,Weak Lensing of the CMB: A Harmonic Approach,"Weak lensing of CMB anisotropies and polarization for the power spectra and
+higher order statistics can be handled directly in harmonic-space without
+recourse to real-space correlation functions. For the power spectra, this
+approach not only simplifies the calculations but is also readily generalized
+from the usual flat-sky approximation to the exact all-sky form by replacing
+Fourier harmonics with spherical harmonics. Counterintuitively, due to the
+nonlinear nature of the effect, errors in the flat-sky approximation do not
+improve on smaller scales. They remain at the 10% level through the acoustic
+regime and are sufficiently large to merit adoption of the all-sky formalism.
+For the bispectra, a cosmic variance limited detection of the correlation with
+secondary anisotropies has an order of magnitude greater signal-to-noise for
+combinations involving magnetic parity polarization than those involving the
+temperature alone. Detection of these bispectra will however be severely noise
+and foreground limited even with the Planck satellite, leaving room for
+improvement with higher sensitivity experiments. We also provide a general
+study of the correspondence between flat and all sky potentials, deflection
+angles, convergence and shear for the power spectra and bispectra.",0001303v1
+2000-02-27,Limits on Hot Intracluster Gas Contributions to the Tenerife Temperature Anisotropy Map,"We limit the contribution of the hot intracluster gas, by means of the
+Sunyaev-Zel'dovich effect, to the temperature anisotropies measured by the
+Tenerife experiment. The data is cross-correlated with maps generated from the
+ACO cluster catalogue, the ROSAT PSPC catalogue of clusters of galaxies, a
+catalogue of superclusters and the HEAO 1 A-1 map of X-ray sources. There is no
+evidence of contamination by such sources at an rms level of $\sim 8\mu$K at
+99% confidence level at $5^o$ angular resolution. We place an upper limit on
+the mean Comptonization parameter of $ y \le 1.5\times 10^{-6}$ at the same
+level of confidence. These limits are slightly more restrictive than those
+previously found by a similar analysis on the COBE/DMR data and indicate that
+most of the signal measured by Tenerife is cosmological.",0002497v1
+2000-03-24,A Characteristic Scale on the Cosmic Microwave Sky,"The current suite of results from Cosmic Microwave Background anisotropy
+experiments is fulfilling the promise of providing extraordinary levels of
+discrimination between cosmological models. We calculate a binned anisotropy
+power spectrum, which we tabulate, along with error bars and bin-to-bin
+correlations, so that it can be easily used for constraining models. The
+resulting power spectrum is flat at large angles, with a gradual rise to a
+prominent peak at around 0.5 degrees and a decrease thereafter. This is
+precisely the shape predicted by inflationary-inspired adiabatic models. Within
+that class of cosmologies, this characteristic scale imprinted on the CMB sky
+can be used to infer that the geometry of the Universe is very close to flat.
+The next wave of CMB results should add fuel to the debate about whether or not
+the Universe once inflated, as well as beginning in earnest the task of
+measuring cosmological parameters.",0003393v1
+2000-04-18,"Galaxy Cluster Baryon Fractions, Cluster Surveys and Cosmology","The properties of nearby galaxy clusters limit the range of cosmological
+parameters consistent with our universe. We describe the limits which arise
+from studies of the intracluster medium (ICM) mass fraction fICM and
+consideration of the possible sources of systematic error:
+Omega_M<0.44h_{50}^{-1/2} at 95% confidence. We emphasize that independent of
+Type Ia supernovae (SNe Ia) observations, this cluster study, taken together
+with published cosmic microwave background (CMB) anisotropy studies, indicates
+a non-zero quintessence or dark energy component Omega_Q>0.
+  We then discuss future galaxy cluster surveys which will probe the abundance
+of galaxy clusters to intermediate and high redshift. We investigate the
+sensitivity of these surveys to the cosmological density parameter Omega_M and
+the equation of state parameter w of any quintessence component. In particular,
+we show that cluster survey constraints from a proposed large solid angle X-ray
+survey are comparable in precision and complementary in nature to constraints
+expected from future CMB anisotropy and SNe Ia studies.",0004244v1
+2000-05-11,Synchrotron Emission from Hot Accretion Flows and the Cosmic Microwave Background Anisotropy,"Current estimates of number counts of radio sources in the frequency range
+where the most sensitive Cosmic Microwave Background (CMB) experiments are
+carried out significantly under-represent sources with strongly inverted
+spectra. Hot accretion flows around supermassive black holes in the nuclei of
+nearby galaxies are expected to produce inverted radio spectra by thermal
+synchrotron emission. We calculate the temperature fluctuations and power
+spectra of these sources in the Planck Surveyor 30 GHz energy channel, where
+their emission is expected to peak. We find that their potential contribution
+is generally comparable to the instrumental noise, and approaches the CMB
+anisotropy level at small angular scales. Forthcoming CMB missions, which will
+provide a large statistical sample of inverted-spectra sources, will be crucial
+for determining the distribution of hot accretion flows in nearby quiescent
+galactic nuclei. Detection of these sources in different frequency channels
+will help constrain their spectral characteristics, hence their physical
+properties.",0005244v1
+2000-05-17,Big Bang Leftovers in the Microwave: Cosmology with the Cosmic Microwave Background Radiation,"We combine detections of anisotropy in the Cosmic Microwave Background
+radiation with observations of inhomogeneity in the large-scale distribution of
+galaxies to test the predictions of models of cosmological structure formation.
+This combination probes spatial scales varying by three orders of magnitude,
+including a significant region where the two types of data overlap. We examine
+Cold Dark Matter models with adiabatic density perturbations, isocurvature
+models, and a topological defects model. We set upper limits on the neutrino
+mass and find the primordial power spectrum needed to reconcile an apparent
+disagreement between structure formation observations and direct observations
+of cosmological parameters.
+  Present and future observations of Cosmic Microwave Background anisotropy
+suffer from foreground contamination. We develop detailed predictions for
+microwave emission from radio and infrared-bright galaxies and the
+Sunyaev-Zeldovich effect from clusters. We present realistic simulations of the
+microwave sky, produced as part of the `WOMBAT Challenge' exercise, and
+introduce a pixel-space method for subtracting foreground contamination which
+can be tested on these simulations.",0005365v1
+2000-06-27,Slow-roll inflation and CMB anisotropy data,"We emphasize that the estimation of cosmological parameters from cosmic
+microwave background (CMB) anisotropy data, such as the recent high resolution
+maps from BOOMERanG and MAXIMA-1, requires assumptions about the primordial
+spectra. The latter are predicted from inflation. The physically best-motivated
+scenario is that of slow-roll inflation. However, very often, the unphysical
+power-law inflation scenario is (implicitly) assumed in the CMB data analysis.
+We show that the predicted multipole moments differ significantly in both
+cases. We identify several misconceptions present in the literature (and in the
+way inflationary relations are often combined in popular numerical codes). For
+example, we do not believe that, generically, inflation predicts the relation
+n_S - 1 = n_T for the spectral indices of scalar and tensor perturbations or
+that gravitational waves are negligible. We calculate the CMB multipole moments
+for various values of the slow-roll parameters and demonstrate that an
+important part of the space of parameters (n_S, n_T) has been overlooked in the
+CMB data analysis so far.",0006392v2
+2000-07-03,How accurately can we measure weak gravitational shear?,"With the recent detection of cosmic shear, the most challenging effect of
+weak gravitational lensing has been observed. The main difficulties for this
+detection were the need for a large amount of high quality data and the control
+of systematics during the gravitational shear measurement process, in
+particular those coming from the Point Spread Function anisotropy. In this
+paper we perform detailed simulations with the state-of-the-art algorithm
+developed by Kaiser, Squires and Broadhurst (KSB) to measure gravitational
+shear. We show that for realistic PSF profiles the KSB algorithm can recover
+any shear amplitude in the range $0.012 < |\gammavec |<0.32$ with a relative,
+systematic error of $10-15%$. We give quantitative limits on the PSF correction
+method as a function of shear strength, object size, signal-to-noise and PSF
+anisotropy amplitude, and we provide an automatic procedure to get a reliable
+object catalog for shear measurements out of the raw images.",0007021v2
+2000-07-03,Internal Motions in Globular Clusters,"Observations of internal motions in globular clusters offer unique insights
+into the dynamics of the clusters. We have recently developed methods of
+high-precision astrometry with HST's WFPC2 camera, which allow us to measure
+internal proper motions of individual stars. These new data open up many new
+avenues for study of the clusters. Comparison of the dispersion of proper
+motion with that of radial velocity offers what is potentially the best method
+of measuring cluster distances, but reliable results will require dynamical
+modeling of each cluster. Proper motions are much better able to measure
+anisotropy of stellar motions than are radial velocities. In 47 Tucanae we have
+measured thousands of proper motions near the center; their velocity
+distribution is remarkably Gaussian. In two outer fields we have begun to study
+anisotropy, which appears in the high velocities but not in the lower ones,
+contrary to the spheroidal velocity distributions that have commonly been
+assumed.",0007028v1
+2000-07-14,Asymmetric Beams in Cosmic Microwave Background Anisotropy Experiments,"We propose a new formalism to handle asymmetric beams in the data analysis of
+cosmic microwave background anisotropy experiments. For any beam shape, the
+formalism finds the optimal circularly symmetric equivalent and is thus easily
+adaptable to existing data analysis methods. We demonstrate certain key points
+by using a simulated highly elliptic beam, and the beams and data of the
+MAXIMA-1 experiment, where the asymmetry is mild. In particular, we show that
+in both cases the formalism does not bias the angular power spectrum estimates.
+We analyze the limitations of the formalism and find that it is well suited for
+most practical situations.",0007212v2
+2000-07-20,Time-Delay Effect on the cOsmic Background Radiation by Static Gravitational Potential of Clusters,"We present a quantitative analysis of the time-delay effect on the cosmic
+background radiation (CBR) by static gravitational potential of galaxy
+clusters. This is primarily motivated by growing observational evidence that
+clusters have essentially experienced no-evolution since redshift $z\approx1$,
+indicating that the contribution of a time-dependent potential to CBR
+anisotropy discussed in literature could be rather small for the
+dynamically-relaxed clusters. Using the softened isothermal sphere model and
+the universal density profile for the mass distribution of rich clusters, we
+calculate the CBR anisotropy by the time-delay effect and compare it with those
+generated by the thermal and kinematic S-Z effects as well as by the transverse
+motion of clusters. While it is unlikely that the time-delay effect is
+detectable in the current S-Z measurement because of its small amplitude of
+$10^{-6}$-$10^{-7}$ and its achromaticity, it nevertheless leads to an
+uncertainty of $\sim10%$ in the measurement of the kinematic S-Z effect of
+clusters. Future cosmological application of the peculiar velocity of clusters
+to be measured through the S-Z effect should therefore take this uncertainty
+into account.",0007299v1
+2000-07-25,New Constraints on inflation from the Cosmic Microwave Background,"The recent data from the Boomerang and MAXIMA-1 balloon flights have marked
+the beginning of the precision era of Cosmic Microwave Background anisotropy
+(CMB) measurements. We investigate the observational constraints from the
+current CMB anisotropy measurements on the simplest inflation models,
+characterized by a single scalar field $\phi$, in the parameter space
+consisting of scalar spectral index $n_S$ and tensor/scalar ratio $r$. If we
+include constraints on the baryon density from big bang nucleosynthesis (BBN),
+we show that the favored inflationary models have negligible tensor amplitude
+and a ``red'' tilt, with a best fit of $n_S \simeq 0.93$, which is consistent
+with the simplest ``small-field'' inflation models, but rules out large-field
+models at the $1\sigma$ level. Without including BBN constraints, a broader
+range of models are consistent with the data. The best fit (assuming negligible
+reionization) is a scale-invariant spectrum, $n_S \simeq 1$, which includes
+large-field and hybrid scenarios. Large-field models (such as chaotic and
+power-law inflation) with tilt $n_S < 0.9$ are strongly disfavored in all
+cases.",0007375v2
+2000-07-31,Precision Cosmology and the Density of Baryons in the Universe,"Big-bang Nucleosynthesis (BBN) and Cosmic Microwave Background (CMB)
+anisotropy measurements give independent, accurate measurements of the baryon
+density and can test the framework of the standard cosmology. Early CMB data
+are consistent with the longstanding conclusion from BBN that baryons
+constitute a small fraction of matter in the Universe, but may indicate a
+slightly higher value for the baryon density. We clarify precisely what the two
+methods determine, and point out that differing values for the baryon density
+can indicate either an inconsistency or physics beyond the standard models of
+cosmology and particle physics. We discuss other signatures of the new physics
+in CMB anisotropy.",0007454v2
+2000-08-07,The Pseudo-$C_l$ method: Cosmic microwave background anisotropy power spectrum statistics for high precision cosmology,"As the era of high precision cosmology approaches, the empirically determined
+power spectrum of the microwave background anisotropy $C_l$ will provide a
+crucial test for cosmological theories. We present an exact semi-analytic
+framework for the study of the ampling statistics of the $C_l$ resulting from
+observations with partial sky coverage and anisotropic noise distributions.
+This includes space-borne, air-borne and ground-based experiments. We apply
+this theory to demonstrate its power for constructing fast but unbiased
+approximate methods for the joint estimation of cosmological parameters.
+Further applications, such as a test for possible non-Gaussianity of the
+underlying theory and a ``poor man's power spectrum estimator'' are suggested.
+An appendix derives recursion relations for the efficient computation of the
+couplings between spherical harmonics on the cut sky.",0008111v1
+2000-09-19,Cosmic Defects and CMB anisotropy,"Recent measurements of the cosmic microwave background (CMB) anisotropies by
+BOOMERANG and MAXIMA collaborations have tightened the observational
+constraints on theories of structure formation. They disagree with the
+predictions of conventional topological defect models. Considering the fact
+that topological defects are predicted by the majority of realistic particle
+physics models, the exact nature of the constraints imposed by the recent data
+on the population and the properties of the defects must be fully understood.
+We show that the predictions of current cosmic string models can be brought
+into a closer agreement with the observations by choosing a closed universe
+with $\Omega=1.3$ and by including the effects of the small-scale structure and
+radiation products of the strings. These alone, however, are not sufficient for
+obtaining a good fit to the measured shape of the angular power spectrum. To
+fit the data cosmic strings would either have to be correlated on large
+(perhaps superhorizon) scales or would have to possess a higher degree of
+coherence, i.e. be more ``time-correlated'.",0009307v1
+2000-09-27,Implications for quintessence models from MAXIMA-1 and BOOMERANG-98,"Prompted by the recent MAXIMA-1 and BOOMERANG-98 measurements of the cosmic
+microwave background (CMB) anisotropy power spectrum, and motivated by the
+results from the observation of high-redshift Type Ia supernovae, we
+investigate CMB anisotropies in quintessence models in order to characterize
+the nature of the dark energy today. We perform a Bayesian likelihood analysis,
+using the MAXIMA-1 and BOOMERANG-98 published bandpowers, in combination with
+COBE/DMR, to explore the space of quintessence parameters: the quintessence
+energy density \Omega_\phi and equation of state w_\phi. We restrict our
+analysis to flat, scale-invariant, inflationary adiabatic models. We find that
+this simple class of inflationary models, with a quintessence component
+\Omega_\phi < ~0.7, -1 < = w_\phi < ~-0.5, is in good agreement with the data.
+Within the assumptions of our analysis, pure quintessence models seem to be
+slightly favored, although the simple cosmological constant scenario is
+consistent with the data.",0009432v2
+2000-10-17,"Statistical Power, the Bispectrum and the Search for Non-Gaussianity in the CMB Anisotropy","We use simulated maps of the cosmic microwave background anisotropy to
+quantify the ability of different statistical tests to discriminate between
+Gaussian and non-Gaussian models. Despite the central limit theorem on large
+angular scales, both the genus and extrema correlation are able to discriminate
+between Gaussian models and a semi-analytic texture model selected as a
+physically motivated non-Gaussian model. When run on the COBE 4-year CMB maps,
+both tests prefer the Gaussian model. Although the bispectrum has comparable
+statistical power when computed on the full sky, once a Galactic cut is imposed
+on the data the bispectrum loses the ability to discriminate between models.
+Off-diagonal elements of the bispectrum are comparable to the diagonal elements
+for the non-Gaussian texture model and must be included to obtain maximum
+statistical power.",0010333v1
+2000-10-30,A Limit on the Polarized Anisotropy of the Cosmic Microwave Background at Subdegree Angular Scales,"A ground-based polarimeter, PIQUE, operating at 90 GHz has set a new limit on
+the magnitude of any polarized anisotropy in the cosmic microwave background.
+The combination of the scan strategy and full width half maximum beam of 0.235
+degrees gives broad window functions with average multipoles, l = 211+294-146
+and l = 212+229-135 for the E- and B-mode window functions, respectively. A
+joint likelihood analysis yields simultaneous 95% confidence level flat band
+power limits of 14 and 13 microkelvin on the amplitudes of the E- and B-mode
+angular power spectra, respectively. Assuming no B-modes, a 95% confidence
+limit of 10 microkelvin is placed on the amplitude of the E-mode angular power
+spectrum alone.",0010592v1
+2000-12-13,Evidence for an inflationary phase transition from the LSS and CMB anisotropy data,"In the light of the recent Boomerang and Maxima observations of the CMB which
+show an anomalously low second acoustic peak, we reexamine the prediction by
+Adams et al (1997) that this would be the consequence of a 'step' in the
+primordial spectrum induced by a spontaneous symmetry breaking phase transition
+during primordial inflation. We demonstrate that a deviation from
+scale-invariance around $k\sim0.1h$~Mpc$^{-1}$ can simultaneously explain both
+the feature identified earlier in the APM galaxy power spectrum as well the
+recent CMB anisotropy data, with a baryon density consistent with the BBN
+value. Such a break also allows a good fit to the data on cluster abundances
+even for a critical density matter-dominated universe with zero cosmological
+constant.",0012284v1
+2001-01-11,How to Avoid the Ambiguity in Applying the Copernican Principle for Cosmic Topology: Take the Observational Approach,"It is often stated that homogeneity and isotropy of the Universe are
+assumptions of the almost Friedmann-Lema^itre (FL) model (the hot big bang
+model), inspired from the Copernican Principle. However, only local homogeneity
+and isotropy are required by the model: multiply connected almost FL models are
+locally homogeneous and isotropic, but they can be globally anisotropic and/or
+globally inhomogeneous. Toy models are used here to show how global anisotropy
+and/or global inhomogeneity of an almost FL model could be shown directly in
+observations. This approach may avoid having to make any assumptions regarding
+global anisotropy and inhomogeneity.",0101191v1
+2001-02-08,Early-universe constraints on a time-varying fine structure constant,"Higher-dimensional theories have the remarkable feature of predicting a time
+(and hence redshift) dependence of the `fundamental' four dimensional constants
+on cosmological timescales. In this paper we update the bounds on a possible
+variation of the fine structure constant alpha at the time of BBN (z =10^10)
+and CMB (z=10^3). Using the recently-released high-resolution CMB anisotropy
+data and the latest estimates of primordial abundances of 4He and D, we do not
+find evidence for a varying alpha at more than one-sigma level at either epoch.",0102144v4
+2001-02-25,Probing the Evolution of Gas Mass Fraction with Sunyaev-Zel'dovich Effect,"Study of the primary anisotropies of the Cosmic Microwave Background (CMB)
+can be used to determine the cosmological parameters to a very high precision.
+The power spectrum of the secondary CMB anisotropies due to the thermal
+Sunyaev-Zel'dovich Effect (SZE) by clusters of galaxies, can then be studied,
+to constrain more cluster specific properties (like gas mass). We show the SZE
+power spectrum from clusters to be a sensitive probe of any possible evolution
+(or constancy) of the gas mass fraction. The position of the peak of the SZE
+power spectrum is a strong discriminatory signature of different gas mass
+fraction evolution models. For example, for a flat universe, there can be a
+difference in the $l$ values (of the peak) of {\it as much as 3000} between a
+constant gas mass fraction model and an evolutionary one. Moreover,
+observational determination of power spectrum, from blank sky surveys, is
+devoid of any selection effects that can possibly affect targeted X-ray or
+radio studies of gas mass fractions in galaxy clusters.",0102430v1
+2001-05-10,Cosmic Microwave Background Anisotropy with Cosine-Type Quintessence,"We study the Cosmic Microwave Background (CMB) anisotropies produced by
+cosine-type quintessence models. In our analysis, effects of the adiabatic and
+isocurvature fluctuations are both taken into account. For purely adiabatic
+fluctuations with scale invariant spectrum, we obtain a stringent constraint on
+the model parameters using the CMB data from COBE, BOOMERanG and MAXIMA.
+Furthermore, it is shown that isocurvature fluctuations have significant
+effects on the CMB angular power spectrum at low multipoles in some parameter
+space, which may be detectable in future satellite experiments. Such a signal
+may be used to test the cosine-type quintessence models.",0105161v2
+2001-05-14,Understanding Cluster Gas Evolution and Fine-Scale CMB Anisotropy with Deep Sunyaev-Zel'dovich Effect Surveys,"We investigate the impact of gas evolution on the expected yields from deep
+Sunyaev-Zel'dovich (SZ) effect surveys as well as on the expected SZ effect
+contribution to fine scale anisotropy in the Cosmic Microwave Background. The
+approximate yields from SZ effect surveys are remarkably insensitive to gas
+evolution, even though the observable properties of the resulting clusters can
+be markedly different. The CMB angular power spectrum at high multipoles due to
+the SZ effect from clusters is quite sensitive to gas evolution. We show that
+moderate resolution SZ effect imaging of clusters found in deep SZ effect
+surveys should allow a good understanding of gas evolution in galaxy clusters,
+independent of the details of the nature of the gas evolution. Such an
+understanding will be necessary before precise cosmological constraints can be
+set from yields of large cluster surveys.",0105229v1
+2001-05-17,MASTER of the CMB Anisotropy Power Spectrum: A Fast Method for Statistical Analysis of Large and Complex CMB Data Sets,"We describe a fast and accurate method for estimation of the cosmic microwave
+background (CMB) anisotropy angular power spectrum --- Monte Carlo Apodised
+Spherical Transform EstimatoR. Originally devised for use in the interpretation
+of the Boomerang experimental data, MASTER is both a computationally efficient
+method suitable for use with the currently available CMB data sets (already
+large in size, despite covering small fractions of the sky, and affected by
+inhomogeneous and correlated noise), and a very promising application for the
+analysis of very large future CMB satellite mission products.",0105302v1
+2001-05-21,The lepton asymmetry: the last chance for a critical-density cosmology?,"We use a wide range of observations to constrain cosmological models
+possessing a significant asymmetry in the lepton sector, which offer perhaps
+the best chance of reconciling a critical-density Universe with current
+observations. The simplest case, with massless neutrinos, fails to fit many
+experimental data and does not lead to an acceptable model. If the neutrinos
+have mass of order one electron-volt (which is favoured by some neutrino
+observations), then models can be implemented which prove a good fit to
+microwave anisotropies and large-scale structure data. However, taking into
+account the latest microwave anisotropy results, especially those from
+Boomerang, we show that the model can no longer accommodate the observed baryon
+fraction in clusters. Together with the observed acceleration of the present
+Universe, this puts considerable pressure on such critical-density models.",0105361v1
+2001-05-23,Mapping the Dark Matter through the CMB Damping Tail,"The lensing of CMB photons by intervening large-scale structure leaves a
+characteristic imprint on its arcminute-scale anisotropy that can be used to
+map the dark matter distribution in projection on degree scales or ~100 Mpc/h
+comoving. We introduce a new algorithm for mass reconstruction which optimally
+utilizes information from the weak lensing of CMB anisotropies in the damping
+tail. It can ultimately map individual degree scale mass structures with high
+signal-to-noise. To achieve this limit an experiment must produce a high
+signal-to-noise, foreground-free CMB map of arcminute scale resolution,
+specifically with a FWHM beam of < 5' and a noise level of < 15 (10^-6-arcmin)
+or 41 (uK-arcmin).",0105424v2
+2001-06-08,"Archeops: A High Resolution, Large Sky Coverage Balloon Experiment for Mapping CMB Anisotropies","Archeops is a balloon-borne instrument dedicated to measuring cosmic
+microwave background (CMB) temperature anisotropies at high angular resolution
+(8 arcminutes) over a large fraction (25%) of the sky in the millimetre domain.
+Based on Planck High Frequency Instrument (HFI) technology, cooled bolometers
+(0.1 K) scan the sky in total power mode with large circles at constant
+elevation. During the course of a 24-hour Arctic-night balloon flight, Archeops
+will observe a complete annulus on the sky in four frequency bands centered at
+143, 217, 353 and 545 GHz with an expected sensitivity to CMB fluctuations of
+\~100muK for each of the 90 thousand 20 arcminute average pixels. We describe
+the instrument and its performance obtained during a test flight from Trapani
+(Sicily) to Spain in July 1999.",0106152v1
+2001-07-18,Elliptical Beams in CMB Temperature and Polarization Anisotropy Experiments: An Analytic Approach,"We present an analytic approach to the estimation of beam asymmetry effects
+in CMB temperature and linear polarization anisotropy experiments. We derive
+via perturbative expansions simple and accurate results for the case of an
+elliptical Gaussian window. Our results are applied to investigate the effect
+of beam ellipticity in the estimation of full-sky polarization correlation
+functions and the covariance matrix of power spectra. The relevance of this
+effect is also discussed by forecasting errors including beam asymmetry for
+current and future CMB experiments.",0107346v2
+2001-08-03,WIMPS Are Stronger When They Stick Together,"Weakly interacting massive particles (WIMPs) remain the strongest candidates
+for the dark matter in the Universe. If WIMPs are the dark matter, they will
+form galactic halos according to the hierarchical clustering observed in N-body
+simulations. Cold dark matter (CDM) simulations show that large dark matter
+structures such as galactic and cluster halos are formed by the merging of many
+smaller clumps of dark matter. Each clump or halo is characterized by a
+centrally cusped density profile that can enhance the rate of WIMP annihilation
+and make the annihilation products more easily detectable. Electrons and
+positrons generated as decay products of WIMP annihilation emit synchrotron
+radiation in the Galactic magnetic field. We study the synchrotron signature
+from the clumps of dark matter in our Galactic halo. We find that the emission
+in the radio and microwave region of the electromagnetic spectrum can be above
+the CMB anisotropy level and should be detectable by CMB anisotropy
+experiments. Depending on the density profile of dark matter clumps, hundreds
+of clumps can have detectable fluxes and angular sizes.",0108060v1
+2001-08-14,Neural Networks as a tool for parameter estimation in mega-pixel data sets,"We present a neural net algorithm for parameter estimation in the context of
+large cosmological data sets. Cosmological data sets present a particular
+challenge to pattern-recognition algorithms since the input patterns (galaxy
+redshift surveys, maps of cosmic microwave background anisotropy) are not fixed
+templates overlaid with random noise, but rather are random realizations whose
+information content lies in the correlations between data points. We train a
+``committee'' of neural nets to distinguish between Monte Carlo simulations at
+fixed parameter values. Sampling the trained networks using additional Monte
+Carlo simulations generated at intermediate parameter values allows accurate
+interpolation to parameter values for which the networks were never trained.
+The Monte Carlo samples automatically provide the probability distributions and
+truth tables required for either a frequentist or Bayseian analysis of the one
+observable sky. We demonstrate that neural networks provide unbiased parameter
+estimation with comparable precision as maximum-likelihood algorithms but
+significant computational savings. In the context of CMB anisotropies, the
+computational cost for parameter estimation via neural networks scales as
+$N^{3/2}$. The results are insensitive to the noise levels and sampling schemes
+typical of large cosmological data sets and provide a desirable tool for the
+new generation of large, complex data sets.",0108234v1
+2001-08-31,"Big Bang Nucleosynthesis, Cosmic Microwave Background Anisotropies and Dark Energy","Over the last decade, cosmological observations have attained a level of
+precision which allows for very detailed comparison with theoretical
+predictions. We are beginning to learn the answers to some fundamental
+questions, using information contained in Cosmic Microwave Background
+Anisotropy (CMBA) data. In this talk, we briefly review some studies of the
+current and prospected constraints imposed by CMBA measurements on the neutrino
+physics and on the dark energy. As it was already announced by Scott (1999), we
+present some possible ""new physics"" from the Cosmic Microwave Background.",0108515v2
+2001-10-01,On the Global Anisotropy of Cosmic Ray Data above $4 \times 10^{19}eV$,"The distribution of arrival directions of ultra-high energy cosmic rays may
+yield clues to their mysterious origin. We introduce a method of {\it invariant
+statistics} to analyze cosmic ray data which eliminates coordinate-dependent
+artifacts. When combined with maximum likelihood analysis, the method is
+capable of quantifying deviations of the distribution from isotropy with high
+reliability. We test our method against published AGASA events with energies
+above $4 \times 10^{19}$ eV. Angular cuts from observational limitations are
+taken into account. A model based on the Fisher distribution reveals the
+rotation of the Earth with the axis $\hat n$ along the direction ($5^h 53.36^m,
+85.78^{\circ}$) in $(RA,DEC)$ coordinates, which is within $5^{\circ}$ of the
+equatorial north pole. Global anisotropy of the data, if any, hinges on finer
+understanding of detector acceptance than what is available from the published
+literature.",0110045v2
+2001-10-18,Weak Lensing of the CMB: Power Spectrum Covariance,"We discuss the non-Gaussian contribution to the power spectrum covariance of
+cosmic microwave background (CMB) anisotropies resulting through weak
+gravitational lensing angular deflections and the correlation of deflections
+with secondary sources of temperature fluctuations generated by the large scale
+structure, such as the integrated Sachs-Wolfe effect and the Sunyave-Zel'dovich
+effect. This additional contribution to the covariance of binned angular power
+spectrum, beyond the well known cosmic variance and any associated instrumental
+noise, results from a trispectrum, or a four point correlation function, in
+temperature anisotropy data. With substantially wide bins in multipole space,
+the resulting non-Gaussian contribution from lensing to the binned power
+spectrum variance is insignificant out to multipoles of a few thousand and is
+not likely to affect the cosmological parameter estimation through acoustic
+peaks and the damping tail. The non-Gaussian contribution to covariance,
+however, should be considered when interpreting binned CMB power spectrum
+measurements at multipoles of a few thousand corresponding to angular scales of
+few arcminutes and less.",0110415v1
+2001-10-19,Galactic Foregrounds in OVRO and UCSB South Pole 1994 Cosmic Microwave Background Anisotropy Data,"We study Galactic emission foreground contamination of the OVRO and UCSB
+South Pole 1994 cosmic microwave background (CMB) anisotropy data by
+cross-correlating with templates of infrared dust emission and new high
+resolution $H_{\alpha}$ data. $H_{\alpha}$ data provide rough upper limits on
+the level of free-free emission in the data sets. The cross-correlation
+analysis does not contradict a two component foreground emission hypothesis,
+with the two dust-correlated components being free-free emission and spinning
+dust emission.",0110457v2
+2001-11-29,Cosmic Inversion: Reconstructing primordial spectrum from CMB anisotropy,"We investigate the possibility of reconstructing the initial spectrum of
+density fluctuations from the cosmic microwave background (CMB) anisotropy. As
+a first step toward this program, we consider a spatially flat, CDM dominated
+universe. In this case, it is shown that, with a good accuracy, the initial
+spectrum satisfies a first order differential equation with the source
+determined by the CMB angular correlation function. The equation is found to
+contain singularities arising from zeros of the acoustic oscillations in the
+transfer functions. Nevertheless, we find these singularities are not fatal,
+and the equation can be solved nicely. We test our method by considering simple
+analytic forms for the transfer functions. We find the initial spectrum is
+reproduced within 5% accuracy even for a spectrum that has a sharp spike.",0111549v1
+2001-12-06,Cosmic String Signatures in the Cosmic Microwave Background Anisotropies,"We briefly review certain aspects of cosmic microwave background anisotropies
+as generated in passive and active models of structure formation. We then focus
+on cosmic strings based models and discuss their status in the light of current
+high-resolution observations from the BOOMERanG, MAXIMA and DASI
+collaborations. Upcoming megapixel experiments will have the potential to look
+for non-Gaussian features in the CMB temperature maps with unprecedented
+accuracy. We therefore devote the last part of this review to treat the
+non-Gaussianity of the microwave background and present a method for
+computation of the bispectrum from simulated string realizations.",0112145v1
+2002-01-12,Cosmological Recombination of Lithium and its Effect on the Microwave Background Anisotropies,"The cosmological recombination history of lithium, produced during Big--Bang
+nucleosynthesis, is presented using updated chemistry and cosmological
+parameters consistent with recent cosmic microwave background (CMB)
+measurements. For the popular set of cosmological parameters, about a fifth of
+the lithium ions recombine into neutral atoms by a redshift $z\sim 400$. The
+neutral lithium atoms scatter resonantly the CMB at 6708 \AA and distort its
+intensity and polarization anisotropies at observed wavelengths around $\sim
+300 \mu$m, as originally suggested by Loeb (2001). The modified anistropies
+resulting from the lithium recombination history are calculated for a variety
+of cosmological models and found to result primarily in a suppression of the
+power spectrum amplitude. Significant modification of the power spectrum occurs
+for models which assume a large primordial abundance of lithium. While
+detection of the lithium signal might prove difficult, if offers the
+possibility of inferring the lithium primordial abundance and is the only probe
+proposed to date of the large-scale structure of the Universe for $z\sim
+500-100$.",0201189v2
+2002-02-26,Cosmic microwave background and large scale structure limits on the interaction between dark matter and baryons,"We study the effect on the cosmic microwave background (CMB) anisotropy and
+large scale structure (LSS) power spectrum of a scattering interaction between
+cold dark matter and baryons. This scattering alters the CMB anisotropy and LSS
+spectrum through momentum transfer between the cold dark matter particles and
+the baryons. We find that current CMB observations can put an upper limit on
+the scattering cross section which is comparable with or slightly stronger than
+previous disk heating constraints at masses greater than 1 GeV, and much
+stronger at smaller masses. When large-scale structure constraints are added to
+the CMB limits, our constraint is more stringent than this previous limit at
+all masses. In particular, a dark matter-baryon scattering cross section
+comparable to the ``Spergel-Steinhardt'' cross section is ruled out for dark
+matter mass greater than 1 GeV.",0202496v2
+2002-06-07,Newtonian motion as origin of anisotropy of the local velocity field of galaxies,"The origins of recently reported anisotropy of the local velocity field of
+nearby galaxies (velocities < 500 km/s corresponding to the distance less than
+8 Mpc) are studied. The exact solution of the Newtonian equation for the
+expanding Universe is obtained. This solution allows us to separate the
+Newtonian motion of nearby galaxies from the Hubble flow by the transition to
+the conformal coordinates. The relation between the Hubble flow and the
+Newtonian motion is established. We show that the anisotropic local velocity
+field of nearby galaxies can be formed by such a Newtonian motion in the
+expanding Universe, if at the moment of the capture of galaxies by the central
+gravitational field.",0206114v6
+2002-06-13,"Morphology of the Secondary CMB Anisotropies: the Key to ""Smoldering"" Reionization","We show how the morphological analysis of the maps of the secondary CMB
+anisotropies can detect an extended period of ``smoldering'' reionization,
+during which the universe remains partially ionized. Neither radio observations
+of the redshifted 21cm line nor IR observations of the redshifted Lyman-alpha
+forest will be able to detect such a period. The most sensitive to this kind of
+non-gaussianity parameters are the number of regions in the excursion set, the
+perimeter of the excursion set, and the genus of the largest (by area) region.
+For example, if the universe reionized fully at z=6, but maintained about 1/3
+mean ionized fraction since z=20, then a 2 arcmin map with 500x500 pixel
+resolution and a signal-to-noise ratio S/N=1/2 allows to detect the
+non-gaussianity due to reionization with better than 99% confidence level.",0206217v1
+2002-06-16,Nonlinear Turbulent Magnetic Diffusion and Mean-Field Dynamo,"The nonlinear coefficients defining the mean electromotive force (i.e., the
+nonlinear turbulent magnetic diffusion, the nonlinear effective velocity, the
+nonlinear kappa-tensor, etc.) are calculated for an anisotropic turbulence. A
+particular case of an anisotropic background turbulence (i.e., the turbulence
+with zero mean magnetic field) with one preferential direction is considered.
+It is shown that the toroidal and poloidal magnetic fields have different
+nonlinear turbulent magnetic diffusion coefficients. It is demonstrated that
+even for a homogeneous turbulence there is a nonlinear effective velocity which
+exhibits diamagnetic or paramagnetic properties depending on anisotropy of
+turbulence and level of magnetic fluctuations in the background turbulence.
+Analysis shows that an anisotropy of turbulence strongly affects the nonlinear
+mean electromotive force. Two types of nonlinearities (algebraic and dynamic)
+are also discussed. The algebraic nonlinearity implies a nonlinear dependence
+of the mean electromotive force on the mean magnetic field. The dynamic
+nonlinearity is determined by a differential equation for the magnetic part of
+the alpha-effect. It is shown that for the alpha-Omega axisymmetric dynamo the
+algebraic nonlinearity alone cannot saturate the dynamo generated mean magnetic
+field while the combined effect of the algebraic and dynamic nonlinearities
+limits the mean magnetic field growth. Astrophysical applications of the
+obtained results are discussed.",0206261v1
+2002-06-20,Sensitivity of the Cosmic Microwave Background Anisotropy to Initial Conditions in Quintessence Cosmology,"We analyze the evolution of energy density fluctuations in cosmological
+scenarios with a mixture of cold dark matter and quintessence, in which the
+quintessence field is modeled by a constant equation of state. We obtain
+analytic expressions for the time evolution of the quintessence perturbations
+in models with light fields. The fluctuations behave analogously to a driven
+harmonic oscillator, where the driving term arises from the inhomogeneities in
+the surrounding cosmological fluid. We demonstrate that the homogeneous
+solution, determined by the initial conditions, is completely sub-dominant to
+the inhomogeneous solution for physically realistic scenarios. Thus we show
+that the cosmic microwave background anisotropy predicted for such models is
+highly insensitive to the initial conditions in the quintessence field.",0206372v2
+2002-08-06,Magnetic field amplification in CDM anisotropic collapse,"We use the Zel'dovich approximation to analyse the amplification of magnetic
+fields in gravitational collapse of cold dark matter during the mildly
+nonlinear regime, and identify two key features. First, the anisotropy of
+collapse effectively eliminates one of the magnetic components, confining the
+field in the pancake plane. Second, in agreement with recent numerical
+simulations, we find that the shear anisotropy can amplify the magnetic field
+well beyond the isotropic case. Our results suggest that the magnetic strengths
+observed in spiral and disk galaxies today might have originated from seeds
+considerably weaker than previous estimates.",0208126v2
+2002-08-10,OVRO CMB Anisotropy Measurement Constraints on Flat-Lambda and Open CDM Cosmogonies,"We use Owens Valley Radio Observatory (OVRO) cosmic microwave background
+(CMB) anisotropy data to constrain cosmological parameters. We account for the
+OVRO beamwidth and calibration uncertainties, as well as the uncertainty
+induced by the removal of non-CMB foreground contamination. We consider open
+and spatially-flat-Lambda cold dark matter cosmogonies, with
+nonrelativistic-mass density parameter Omega_0 in the range 0.1--1,
+baryonic-mass density parameter Omega_B in the range (0.005--0.029)h^{-2}, and
+age of the universe t_0 in the range (10--20) Gyr. Marginalizing over all
+parameters but Omega_0, the OVRO data favors an open (spatially-flat-Lambda)
+model with Omega_0 ~= 0.33 (0.1). At the 2 sigma confidence level model
+normalizations deduced from the OVRO data are mostly consistent with those
+deduced from the DMR, UCSB South Pole 1994, Python I-III, ARGO, MAX 4 and 5,
+White Dish, and SuZIE data sets.",0208216v1
+2002-08-30,The Far-Infrared Background Correlation with CMB Lensing,"The intervening large--scale structure distorts cosmic microwave background
+(CMB) anisotropies via gravitational lensing. The same large--scale structure,
+traced by dusty star--forming galaxies, also induces anisotropies in the
+far--infrared background (FIRB). We investigate the resulting inter--dependence
+of the FIRB and CMB with a halo model for the FIRB. In particular, we calculate
+the cross--correlation between the lensing potential and the FIRB. The lensing
+potential can be quadratically estimated from CMB temperature and/or
+polarization maps. We show that the cross--correlation can be measured with
+high signal--to--noise with data from the Planck Surveyor. We discuss how such
+a measurement can be used to understand the nature of FIRB sources and their
+relation to the distribution of dark matter.",0209001v1
+2002-10-01,Missing Parameters in the CMB Physics,"The lecture is devoted to the comparison of a few models of cosmic
+recombination kinetics with recent CMB anisotropy data and to corresponding
+predictions for the upcoming PLANCK mission. The influence of additional
+sources of ionized photons at the epoch of hydrogen recombination may restrict
+our possibility to estimate the density of baryonic fraction of matter when
+using PLANCK data. This new source of degeneracy of the cosmological parameters
+which can be estimated from the CMB anisotropy data can mimic the distortion of
+the CMB power spectrum for different models of baryonic matter. I would like to
+point out that realistic values of the cosmological parameters can not be
+obtained without PLANCK polarization data.",0210034v1
+2002-10-29,The Inflationary Gravity Waves in light of recent Cosmic Microwave Background Anisotropies data,"One of the major predictions of inflation is the existence of a stochastic
+background of cosmological gravitational waves (GW). These gravitational waves
+can induce significant temperature anisotropies in the Cosmic Microwave
+Background (CMB) on the angular scales recently probed by the Archeops
+experiment. Here, we perform a combined analysis of Archeops together with
+information from other CMB experiments and/or cosmological datasets, in order
+to constrain the amplitude of the GW background. We find that, for a
+scale-invariant GW background, the ratio of tensor/scalar perturbations at the
+CMB quadrupole is now constrained to be $r \leq 0.43$ at 95% c.l., while the
+bound on the spectral index of primordial density fluctuations is
+$n_S=0.97_{-0.12}^{+0.10}$. We discuss the implications for future GW
+detections through CMB polarization measurements.",0210606v3
+2002-11-28,Cosmological Effects of a Class of Fluid Dark Energy Models,"We study the impact of a generalized Chaplygin gas as a candidate for dark
+energy on CMB anisotropies. The generalized Chaplygin gas is a fluid component
+with an exotic equation of state, $p = - A/\rho^\alpha$ (a polytropic gas with
+negative constant and exponent). Such component interpolates in time between
+dust and a cosmological constant, with an intermediate behaviour as $p=\alpha
+\rho$. Perturbations of this fluid are stable on small scales, but behave in a
+very different way with respect to standard quintessence. Moreover, a
+generalized Chaplygin gas could also represent an archetypal example of a
+phenomenological unified models of dark energy and dark matter. The results
+presented here show how the CMB anisotropies induced by this class of models
+differ from a $\Lambda$CDM model.",0211626v1
+2002-12-11,Observational constraints on the curvaton model of inflation,"Simple curvaton models can generate a mixture of of correlated primordial
+adiabatic and isocurvature perturbations. The baryon and cold dark matter
+isocurvature modes differ only by an observationally null mode in which the two
+perturbations almost exactly compensate, and therefore have proportional
+effects at linear order. We discuss the CMB anisotropy in general mixed models,
+and give a simple approximate analytic result for the large scale CMB
+anisotropy. Working numerically we use the latest WMAP observations and a
+variety of other data to constrain the curvaton model. We find that models with
+an isocurvature contribution are not favored relative to simple purely
+adiabatic models. However a significant primordial totally correlated baryon
+isocurvature perturbation is not ruled out. Certain classes of curvaton model
+are thereby ruled out, other classes predict enough non-Gaussianity to be
+detectable by the Planck satellite. In the appendices we review the relevant
+equations in the covariant formulation and give series solutions for the
+radiation dominated era.",0212248v3
+2002-12-28,Turbulent Magnetohydrodynamic Elasticity: I. Boussinesq-like Approximations for Steady Shear,"We re-examine the Boussinesq hypothesis of an effective turbulent viscosity
+within the context of simple closure considerations for models of strong
+magnetohydrodynamic turbulence. Reynolds-stress and turbulent Maxwell-stress
+closure models will necessarily introduce a suite of transport coefficients,
+all of which are to some degree model-dependent. One of the most important
+coefficients is the relaxation time for the turbulent Maxwell stress, which
+until recently has been relatively ignored. We discuss this relaxation within
+the context of magnetohydrodynamic turbulence in steady high Reynolds-number,
+high magnetic-Reynolds-number shearing flows. The relaxation time for the
+turbulent Maxwell stress is not limited by the shear time scale, in contrast
+with Reynolds-stress closure models for purely hydrodynamical turbulence. The
+anisotropy of the turbulent stress tensor for magnetohydrodynamic turbulence,
+even for the case of zero mean-field considered here, can therefore not be
+neglected. This shear-generated anisotropy can be interpreted as being due to
+an effective turbulent elasticity, in analogy to the Boussinesq turbulent
+viscosity. We claim that this turbulent elasticity should be important for any
+astrophysical problem in which the turbulent stress in quasi-steady shear has
+been treated phenomenologically with an effective viscosity.",0212556v1
+2003-01-02,"First Results From an X-ray, Weak Lensing, and Sunyaev-Zeldovich Effect Survey of Nearby Clusters: Abell 3266","As part of a combined Sunyaev-Zeldovich Effect (SZE), X-ray and weak lensing
+survey of low redshift (z<0.1) X-ray clusters, we present SZE images of the
+z=0.059 X-ray cluster Abell 3266 at three observing frequencies (150, 220, 275
+GHz) and after the spectral subtraction of primary Cosmic Microwave Background
+(CMB) anisotropies. These images were generated using the ACBAR bolometer array
+operated on the Viper telescope at the South Pole. The multi-frequency data
+from ACBAR should allow us to overcome one of the main obstacles facing the
+analysis of SZE observations of nearby clusters, i.e. contamination from
+primary Cosmic Microwave Background (CMB) anisotropies.",0301024v1
+2003-01-17,Clues on the Evolution of Cluster Galaxies From The Analysis of Their Orbital Anisotropies,"We study the evolution of galaxies in clusters by the analysis of a sample of
+about 3000 galaxies, members of 59 clusters from the ESO Nearby Abell Cluster
+Survey (ENACS). We distinguish four cluster galaxy populations, based on their
+radial and velocity distributions within the clusters. Using the class of
+ellipticals and S0's (excluding the very bright ellipticals), we determine the
+average cluster mass profile, that we compare with mass models available from
+numerical simulations. We then use this cluster mass profile to solve for the
+anisotropy profiles of the three other cluster galaxy populations, viz. the
+very bright ellipticals, the early spirals, and the late spirals with the
+emission-line galaxies. We discuss the implications of our findings for the
+evolution of cluster galaxies.",0301343v1
+2003-01-29,Galactic Foreground Constraints from the Python V Cosmic Microwave Background Anisotropy Data,"We constrain Galactic foreground contamination of the Python V cosmic
+microwave background anisotropy data by cross correlating it with foreground
+contaminant emission templates. To model foreground emission we use 100 and 12
+$\mu$m dust emission templates and two point source templates based on the PMN
+survey. The analysis takes account of inter-modulation correlations in 8
+modulations of the data that are sensitive to a large range of angular scales
+and also densely sample a large area of sky. As a consequence the analysis here
+is highly constraining. We find little evidence for foreground contamination in
+an analysis of the whole data set. However, there is indication that
+foregrounds are present in the data from the larger-angular-scale modulations
+of those Python V fields that overlap the region scanned earlier by the UCSB
+South Pole 1994 experiment. This is an independent consistency cross-check of
+findings from the South Pole 1994 data.",0301581v2
+2003-02-02,Evidence for anisotropy in the distribution of short-lived gamma-ray bursts,"Measurements of the two-point angular correlation function w(\theta) for 407
+short gamma-ray bursts collected in the Current BATSE Catalogue reveal a ~2
+\sigma deviation from isotropy on angular scales \theta ~ 2-4 degrees. Such an
+anisotropy is not observed in the distribution of long gamma-ray bursts and
+hints to the presence of repeated bursts for up to ~13% of the sources under
+exam. However, the available data cannot exclude the signal as due to the
+presence of large-scale structure. Under this assumption, the amplitude of the
+observed w(\theta) is compatible with those derived for different populations
+of galaxies up to redshifts ~0.5, result that suggests short gamma-ray bursts
+to be relatively local sources.",0302009v1
+2003-02-03,Global Anisotropy Versus Small-Scale Fluctuations in Neutrino Flux in Core-Collapse Supernova Explosions,"Effects of small-scale fluctuations in the neutrino radiation on
+core-collapse supernova explosions are examined. Through a parameter study with
+a fixed radiation field of neutrinos, we find substantial differences between
+the results of globally anisotropic neutrino radiation and those with
+fluctuations. As the number of modes of fluctuations increases, the shock
+positions, entropy distributions, and explosion energies approach those of
+spherical explosion. We conclude that global anisotropy of the neutrino
+radiation is the most effective mechanism of increasing the explosion energy
+when the total neutrino luminosity is given. This supports the previous
+statement on the explosion mechanism by Shimizu and coworkers.",0302015v5
+2003-02-05,Cosmic ray spectrum and anisotropies from the knee to the second knee,"We consider the scenario in which the knee in the cosmic ray spectrum is due
+to a change in the escape mechanism of cosmic rays from the Galaxy from one
+dominated by transverse diffusion to one dominated by drifts. We show that this
+scenario explains not only the changes in spectral slope at the knee and at the
+second knee, but can also account for the main characteristics of the observed
+energy dependent anisotropy amplitude and phase of first harmonic in the energy
+range between $10^{15}$ and $10^{18}$ eV. This provides a useful handle to
+distinguish this diffusion/drift model from other scenarios proposed to explain
+the knee in the spectrum.",0302082v2
+2003-02-05,Late reionizations of the Universe and their manifestation in the CMB data,"We investigate two sets of two-epoched reionization models and their
+manifestation in the CMB anisotropy and polarization data of the recent WMAP
+project and make some predictions for the future PLANCK missions. In the first
+set of models, the universe was reionized twice, first at z~15 by population
+III stars and then at z~6 by stars in large galaxies. In the second set of
+models, the extra peak-like reionization at high redshifts z > 100 is induced
+by the decay of unstable particles, followed by the standard picture of
+reionization at z~6. We examine the general properties of these two-epoched
+reionization models and their implication in the WMAP CMB temperature
+anisotropy-polarization cross-correlation. We have shown that these models have
+comparable likelihood values for the WMAP data and distinct characters which
+can be tested with the Planck high sensitivities.",0302085v3
+2003-02-25,Early Quintessence in Light of WMAP,"We examine the cosmic microwave background (CMB) anisotropy for signatures of
+early quintessence dark energy -- a non-negligible quintessence energy density
+during the recombination and structure formation eras. Only very recently does
+the quintessence overtake the dark matter and push the expansion into
+overdrive. Because the presence of early quintessence exerts an influence on
+the clustering of dark matter and the baryon-photon fluid, we may expect to
+find trace signals in the CMB and the mass fluctuation power spectrum. In
+detail, we demonstrate that suppressed clustering power on small length-scales,
+as suggested by the combined Wilkinson Microwave Anisotropy Probe (WMAP) / CMB
+/ large scale structure data set, is characteristic of early quintessence. We
+identify a set of concordant models, and map out directions for further
+investigation of early quintessence.",0302505v2
+2003-03-05,Spectral Properties of Compressible Magnetohydrodynamic Turbulence from Numerical Simulations,"We analyze the spectral properties of driven, supersonic compressible
+magnetohydrodynamic (MHD) turbulence obtained via high-resolution numerical
+experiments, for application to understanding the dynamics of giant molecular
+clouds. Via angle-averaged power spectra, we characterize the transfer of
+energy from the intermediate, driving scales down to smaller dissipative
+scales, and also present evidence for inverse cascades that achieve
+modal-equipartition levels on larger spatial scales. Investigating compressive
+versus shear modes separately, we evaluate their relative total power, and find
+that as the magnetic field strength decreases, (1) the shear fraction of the
+total kinetic power decreases, and (2) slopes of power-law fits over the
+inertial range steepen. To relate to previous work on incompressible MHD
+turbulence, we present qualitative and quantitative measures of the
+scale-dependent spectral anisotropy arising from the shear-Alfv\'{e}n cascade,
+and show how these vary with changing mean magnetic field strength. Finally, we
+propose a method for using anisotropy in velocity centroid maps as a diagnostic
+of the mean magnetic field strength in observed cloud cores.",0303103v1
+2003-03-10,Annual modulation in the scattering of J1819+3845: peculiar plasma velocity and anisotropy,"We present two years of monitoring observations of the extremely variable
+quasar J1819+3845. We observe large yearly changes in the timescale of the
+variations (from ~ 1 hour to ~ 10 hours at 5GHz). This annual effect can only
+be explained if the variations are caused by a propagation effect, and thus
+affected by the Earth's relative speed through the projected intensity pattern.
+To account for this effect, the scattering plasma must have a transverse
+velocity with respect to the local standard of rest.
+  The velocity calculated from these observations is in good agreement with
+that obtained from a two telescope delay experiment (Dennett-Thorpe & de Bruyn
+2001). We also show that either the source itself is elongated, or that the
+scattering plasma is anisotropic, with an axial ratio of >6:1. As the source is
+extended on scales relevant to the scattering phenomenon, it seems plausible
+that the anisotropy is due to the source itself, but this remains to be
+investigated. From the scintillation characteristics we find that the
+scattering material is a very strong, thin scatterer within ~ten parsecs. We
+determine a source size at 5GHz of 100 to 900microarcsecs, and associated
+brightness temperatures of 10^{10} to 10^{12}K.",0303201v1
+2003-05-09,Full-Sky Search for Ultra High Energy Cosmic Ray Anisotropies,"Using data from the SUGAR and the AGASA experiments taken during a 10 yr
+period with nearly uniform exposure to the entire sky, we search for
+large-scale anisotropy patterns in the arrival directions of cosmic rays with
+energies > 10^{19.6} eV. We determine the angular power spectrum from an
+expansion in spherical harmonics for modes out to \ell=5. Based on available
+statistics, we find no significant deviation from isotropy. We compare the
+rather modest results which can be extracted from existing data samples with
+the results that should be forthcoming as new full-sky observatories begin
+operation.",0305158v3
+2003-05-14,The shape of the CMB power spectrum,"The recent WMAP data represents a milestone in cosmology and helps constrain
+cosmological parameters with unprecedented accuracy. In this work we combine
+the WMAP data with previous CMB anisotropy measurements at smaller angular
+scales to characterize the shape of the CMB anisotropy power spectrum. We carry
+out a phenomenological analysis of the data. By allowing non-physical shapes of
+the power spectrum we analyse high and low frequency experiments separately and
+together. We find that WMAP dramatically constrains the power spectrum up to l
+\~ 700. On smaller scales, the data show discrepancies that can be associated
+with experimental systematics. If we combine all types of experiments, the
+observable features in the power spectrum are in excellent agreement with the
+WMAP cosmological parameter estimation. This work illustrates the advantages of
+a model-independent approach to understanding experimental systematics that
+might affect CMB observations.",0305254v1
+2003-05-26,Small-scale CMB Temperature and Polarization Anisotropies due to Patchy Reionization,"We study contributions from inhomogeneous (patchy) reionization to arcminute
+scale ($1000 < \ell < 10,000$) cosmic microwave background (CMB) anisotropies.
+We show that inhomogeneities in the ionization fraction, rather than in the
+mean density, dominate both the temperature and the polarization power spectra.
+Depending on the ionization history and the clustering bias of the ionizing
+sources, we find that rms temperature fluctuations range from 2 $\mu$K to 8
+$\mu$K and the corresponding values for polarization are over two orders of
+magnitude smaller. Reionization can significantly bias cosmological parameter
+estimates and degrade gravitational lensing potential reconstruction from
+temperature maps but not from polarization maps. We demonstrate that a simple
+modeling of the reionization temperature power spectrum may be sufficient to
+remove the parameter bias. The high-$\ell$ temperature power spectrum will
+contain some limited information about the sources of reionization.",0305471v2
+2003-06-01,Tests of Statistical Significance and Background Estimation in Gamma Ray Air Shower Experiments,"In this paper we discuss several methods of significance calculation and
+point out the limits of their applicability. We then introduce a self
+consistent scheme for source detection and discuss some of its properties. The
+method allows incorporating background anisotropies by vetoing existing small
+scale regions on the sky and compensating for known large scale anisotropies.
+By giving an example using Milagro gamma ray observatory we demonstrate how the
+method can be employed to relax the detector stability assumption. Two
+practical implementations of the method are discussed. The method is universal
+and can be used with any large field-of-view detector, where the object of
+investigation, steady or transient, point or extended, traverses its field of
+view.",0306015v1
+2003-06-21,The Statistical Significance of the Low CMB Mulitipoles,"The Wilkinson Microwave Anisotropy Probe (WMAP) has measured lower amplitudes
+for the temperature quadrupole and octopole anisotropies than expected in the
+best fitting (concordance) Lambda-dominated cold dark matter cosmology. Some
+authors have argued that this discrepancy may require new physics. Yet the
+statistical significance of this result is not clear. Some authors have applied
+frequentist arguments and claim that the discrepancy would occur by chance
+about 1 time in 700 if the concordance model is correct. Other authors have
+used Bayesian arguments to claim that the data show marginal evidence for new
+physics. I investigate these confusing and apparently conflicting claims using
+a frequentist analysis and a simplified Bayesian analysis. I conclude that the
+WMAP results are consistent with the concordance Lambda CDM model.",0306431v3
+2003-07-05,Large Scale Cosmic Microwave Background Anisotropies and Dark Energy,"In this note we investigate the effects of perturbations in a dark energy
+component with a constant equation of state on large scale cosmic microwave
+background anisotropies. The inclusion of perturbations increases the large
+scale power. We investigate more speculative dark energy models with w<-1 and
+find the opposite behaviour. Overall the inclusion of perturbations in the dark
+energy component increases the degeneracies. We generalise the parameterization
+of the dark energy fluctuations to allow for an arbitrary const ant sound
+speeds and show how constraints from cosmic microwave background experiments
+change if this is included. Combining cosmic microwave background with large
+scale structure, Hubble parameter and Supernovae observations we obtain
+w=-1.02+-0.16 (1 sigma) as a constraint on the equation of state, which is
+almost independent of the sound speed chosen. With the presented analysis we
+find no significant constraint on the constant speed of sound of the dark
+energy component.",0307104v2
+2003-07-31,Statistical isotropy of the Cosmic Microwave Background,"The breakdown of statistical homogeneity and isotropy of cosmic perturbations
+is a generic feature of ultra large scale structure of the cosmos, in
+particular, of non trivial cosmic topology. The statistical isotropy (SI) of
+the Cosmic Microwave Background temperature fluctuations (CMB anisotropy) is
+sensitive to this breakdown on the largest scales comparable to, and even
+beyond the cosmic horizon. We propose a set of measures, $\kappa_\ell$
+($\ell=1,2,3, ...$) which for non-zero values indicate and quantify statistical
+isotropy violations in a CMB map. We numerically compute the predicted
+$\kappa_\ell$ spectra for CMB anisotropy in flat torus universe models.
+Characteristic signature of different models in the $\kappa_\ell$ spectrum are
+noted.",0308002v1
+2003-09-11,Optimized in-flight absolute calibration for extended CMB surveys,"Accurate measurements of the Cosmic Microwave Background (CMB) anisotropy
+call for high precision and reliability of the in-flight calibration. For
+extended surveys the CMB dipole provides an excellent calibration source at
+frequencies lower than 200 GHz; however poorly known foreground emissions, such
+as diffuse galactic components, complicate the signal and introduce a
+systematic error in the calibration. We show that introducing a weight function
+that takes into account the uncertainty in the a priori knowledge of the sky,
+allows us to substantially improve the calibration accuracy with respect to
+methods involving galactic latitude cuts. This new method is tested for
+Planck-LFI radiometers at 30 and 100 GHz. On short time scales (less than 1
+day) the absolute calibration of each channel can be recovered with an overall
+1-2% accuracy. We also consider the effect of CMB anisotropy itself on the
+calibration, and find that knowledge of the CMB pattern on large scales is
+needed to keep the short-time scale calibration accuracy within 1%",0309317v1
+2003-09-15,The MAXIMA Experiment: Latest Results and Consistency Tests,"The MAXIMA cosmic microwave background anisotropy experiment had a
+significant impact on cosmology. Results from the program have played a
+significant role in determining the geometry of the universe, given strong
+supporting evidence to inflation, and, in combination with other astrophysical
+data, showed that the universe is filled with dark matter and energy. We
+present a subset of the internal consistency checks that were carried out on
+the MAXIMA-1 data prior to their release, which demonstrate that systematics
+errors were much smaller than statistical errors. We also discuss the MAXIMA-2
+flight and data, compare the maps of MAXIMA-1 and -2 in areas where they
+overlap and show that the two independent experiments confirm each other. All
+of these results demonstrate that MAXIMA mapped the cosmic microwave background
+anisotropy with high accuracy",0309409v1
+2003-09-16,Polarization Measures And Nature Of Dark Energy,"Polarization measures, on wide angular scales, together with anisotropy data,
+can fix DE parameters. Here we discuss the sensitivity needed to provide
+significant limits. Our analysis puts in evidence that a class of models
+predicts low correlation or anticorrelation between polarization and anisotropy
+at low l. This class includes open models and models with DE due to a
+Ratra--Peebles (RP) potential. Results on this point, given in a previous paper
+of ours, are updated and partially corrected. We outline that, with the
+sensitivity of experiments like SPOrt or WMAP, high values of Lambda (energy
+scale in the RP potential) can be excluded. With the sensitivity expected for
+PLANCK, the selection will extend to much lower Lambda's.",0309438v1
+2003-09-25,Evolution of Second-Order Cosmological Perturbations and Non-Gaussianity,"We present a second-order gauge-invariant formalism to study the evolution of
+curvature perturbations in a Friedmann-Robertson-Walker universe filled by
+multiple interacting fluids. We apply such a general formalism to describe the
+evolution of the second-order curvature perturbations in the standard
+one-single field inflation, in the curvaton and in the inhomogeneous reheating
+scenarios for the generation of the cosmological perturbations. Moreover, we
+provide the exact expression for the second-order temperature anisotropies on
+large scales, including second-order gravitational effects and extend the
+well-known formula for the Sachs-Wolfe effect at linear order. Our findings
+clarify what is the exact non-linearity parameter f_NL entering in the
+determination of higher-order statistics such as the bispectrum of Cosmic
+Microwave Background temperature anisotropies. Finally, we compute the level of
+non-Gaussianity in each scenario for the creation of cosmological
+perturbations.",0309692v3
+2003-10-03,Current Status and Perspectives of Cosmic Microwave Background Observations,"Measurements of the cosmic microwave background (CMB) radiation provide a
+unique opportunity for a direct study of the primordial cosmic plasma at
+redshift z ~1000. The angular power spectra of temperature and polarisation
+fluctuations are powerful observational objectives as they encode information
+on fundamental cosmological parameters and on the physics of the early
+universe. A large number of increasingly ambitious balloon-borne and
+ground-based experiments have been carried out following the first detection of
+CMB anisotropies by COBE-DMR, probing the angular power spectrum up to high
+multipoles. The recent data from WMAP provide a new major step forward in
+measurements percision. The ESA mission Planck Surveyor, to be launched in
+2007, is the third-generation satellite devoted to CMB imaging. Planck is
+expected to extract the full cosmological information from temperature
+anisotropies and to open up new fronteers in the CMB field.",0310089v1
+2003-10-06,Dust during the Reionization,"The possibility that population III stars have reionized the Universe at
+redshifts greater than 6 has recently gained momentum with WMAP polarization
+results. Here we analyse the role of early dust produced by these stars and
+ejected into the intergalactic medium. We show that this dust, heated by the
+radiation from the same population III stars, produces a submillimetre excess.
+The electromagnetic spectrum of this excess could account for a significant
+fraction of the FIRAS (Far Infrared Absolute Spectrophotometer) cosmic far
+infrared background above 700 micron. This spectrum, a primary anisotropy
+($\Delta T$) spectrum times the $\nu^2$ dust emissivity law, peaking in the
+submillimetre domain around 750 micron, is generic and does not depend on other
+detailed dust properties. Arcminute--scale anisotropies, coming from
+inhomogeneities in this early dust, could be detected by future submillimetre
+experiments such as Planck HFI.",0310135v2
+2003-10-08,Radio Interferometers with wide bandwidths,"The Australia Telescope Compact Array and the Very Large Array are currently
+being upgraded to operate with wide bandwidths; interferometers dedicated to
+the measurement of cosmic microwave background anisotropies are being designed
+with large instantaneous bandwidths for high sensitivity. Interferometers with
+wide instantaneous bandwidths that do not operate with correlators capable of
+decomposing the bands into narrow channels suffer from `bandwidth smearing'
+effects in wide-field imaging. The formalism of mosaic imaging is extended here
+to interferometers with finite bandwidths to examine the consequences for the
+imaging of wide fields if very wide instantaneous bandwidths are used. The
+formalism presented here provides an understanding of the signal processing
+associated with wide-band interferometers: mosaicing may be viewed as
+decomposing visibilities over wide observing bands and, thereby, avoiding
+`bandwidth smearing' effects in wide-field imaging. In particular, the
+formalism has implications for interferometer measurements of the angular power
+spectrum of cosmic microwave background anisotropies: mosaic-mode observing
+with wide-band radio interferometers decompose wide-band data and synthesize
+narrow filters in multipole space.",0310240v1
+2003-11-18,Anisotropy in the distribution of satellites around primary galaxies in the 2dFGRS: the Holmberg effect,"We have analysed a sample of satellite and primary galaxies in the 2dF galaxy
+redshift survey. In our study we find a strong statistical evidence of the
+Holmberg effect (that is a tendency for satellites to avoid regions along the
+line defined by the primary plane) within 500 kpc of projected distance to the
+primary. This effect is present only when we restrict to objects with radial
+velocity relative to the primary $|\Delta v|<160$ km/s which correspond
+approximately to the mean of the distribution. We explore the dependence of
+this anisotropy on spectral type ($\eta$), colours, and luminosities of both
+primaries and satellites, finding that objects with a low present-day star
+formation rate present the most significant effect.",0311432v1
+2003-12-04,Measuring the Small-Scale Power Spectrum of Cosmic Density Fluctuations Through 21 cm Tomography Prior to the Epoch of Structure Formation,"The thermal evolution of the cosmic gas decoupled from that of the cosmic
+microwave background (CMB) at a redshift z~200. Afterwards and before the first
+stars had formed, the cosmic neutral hydrogen absorbed the CMB flux at its
+resonant 21cm spin-flip transition. We calculate the evolution of the spin
+temperature for this transition and the resulting anisotropies that are
+imprinted on the CMB sky due to linear density fluctuations during this epoch.
+These anisotropies at an observed wavelength of 10.56[(1+z)/50] meters, contain
+an amount of information that is orders of magnitude larger than any other
+cosmological probe. Their detection, although challenging, could tightly
+constrain any possible running of the spectral index from inflation (as
+suggested by WMAP), small deviations from Gaussianity, or any significant
+contribution from neutrinos or warm dark matter to the cosmic mass budget.",0312134v2
+2004-01-05,S-Z Anisotropy & Cluster Counts: Consistent Selection of sigma_8 and the Temperature-Mass Relation,"The strong dependence of the mass variance parameter, sigma_8, on the adopted
+cluster mass-temperature relation is explored. A recently compiled X-ray
+cluster catalog and various mass-temperature relations are used to derive the
+corresponding values of sigma_8. Calculations of the power spectrum of the CMB
+anisotropy induced by the Sunyaev-Zeldovich effect and cluster number counts
+are carried out in order to assess the need for a consistent choice of the
+mass-temperature scaling and the parameter sigma_8. We find that the
+consequences of inconsistent choice of the mass-temperature relation and
+sigma_8 could be quite substantial, including a considerable mis-estimation of
+the magnitude of the power spectrum and cluster number counts. Our results can
+partly explain the large scatter between published estimates of the power
+spectrum and number counts. We also show that the range of values of the
+power-law index in the scaling C_l ~ sigma_8^[6-7] deduced in previous studies
+is likely overestimated; we obtain a more moderate dependence, C_l ~
+sigma_8^[4].",0401033v1
+2004-01-09,Dynamical friction in flattened systems: A numerical test of Binney's approach,"We carry out a set of self-consistent N-body calculations to investigate how
+important the velocity anisotropy in non-spherical dark-matter haloes is for
+dynamical friction. For this purpose we allow satellite galaxies to orbit
+within flattened and live dark-matter haloes (DMHs) with aspect-ratio q_h=0.6
+and compare the resulting orbit evolution with a semi-analytic code. This code
+solves the equation of motion of satellites orbiting within the same DMH and
+implements, according to the dynamical friction model, either Chandrasekhar's
+formula, which does not incorporate the velocity anisotropy, or Binney's
+description of dynamical friction in anisotropic systems. In the numerical and
+the two semi-analytic models the satellites are given different initial orbital
+inclinations and orbital eccentricities.
+  We find that Binney's approach successfully describes the overall satellite
+decay and orbital inclination decrease for the whole set of orbits, with an
+averaged discrepancy of less than 4 per cent in orbital radius during the first
+3 orbits. If Chandrasekhar's expression is used instead, the discrepancy
+increases to 20 per cent and no inclination decrease can be observed. Binney's
+treatment therefore appears to provide a significantly improved treatment of
+dynamical friction in anisotropic systems.",0401159v1
+2004-02-28,Sensitivity of quintessence perturbations to initial conditions,"Gauge invariant quintessence perturbations in the quintessence and cold dark
+matter (QCDM) model are investigated. For three cases of constant
+equation-of-state (EOS) parameter, linear scalar field potential, and
+supergravity scalar field potential, their perturbation evolutions have a
+similar dependence on EOS parameter and scale, but they have different
+sensitivity to the initial conditions due to the different shapes of the
+quintessence potential. They have a minor effect on primary CMB anisotropies,
+but change the secondary CMB effect in different ways. The first case is
+insensitive to initial quintessence perturbations and only modifies the
+Integrated Sachs-Wolfe (ISW) effect within a factor of 2. The other two cases
+are sensitive to initial conditions at large scales and could affect the
+secondary CMB anisotropies drastically depending on how smooth the initial
+perturbations are. This makes it possible for future cosmological probes to
+provide constraints on quintessence properties.",0403006v1
+2004-03-02,Weak Lensing of the CMB by Large-Scale Structure,"Several recent papers have studied lensing of the CMB by large-scale
+structures, which probes the projected matter distribution from $z=10^3$ to
+$z\simeq 0$. This interest is motivated in part by upcoming high resolution,
+high sensitivity CMB experiments, such as APEX/SZ, ACT, SPT or Planck, which
+should be sensitive to lensing. In this paper we examine the reconstruction of
+the large-scale dark matter distribution from lensed CMB temperature
+anisotropies. We go beyond previous work in using numerical simulations to
+include higher order, non-Gaussian effects and study how well the quadratic
+estimator of \cite{Hu01a} is able to recover the input field. We also study
+contamination by kinetic Sunyaev-Zel'dovich signals, which is spectrally
+indistinguishable from lensed CMB anisotropies. We finish by estimating the
+sensitivity of the previously cited experiments.",0403075v2
+2004-03-06,WMAP Constraints on Decaying Cold Dark Matter,"We re-formulate cosmological perturbations in the decaying cold dark matter
+model, and calculate cosmological microwave background (CMB) anisotropies. By
+comparing our theoretical predictions with recent observational data from the
+Wilkinson Microwave Anisotropy Probe(WMAP), we derive a new bound on the
+abundance and lifetime of decaying dark matter particles. We show that the data
+of WMAP alone do not prefer the decaying cold dark matter model: the lifetime
+is constrained to \Gamma^{-1}> 123 Gyr at 68% C.L. (52 Gyr at 95.4% C.L.) when
+cold dark matter consists only of such decaying particles. We also consider a
+more general case in which cold dark matter consists of both stable and
+decaying particles, and show that the constraint generalizes down to
+\Omega_{DDM}h^2 < -0.5 (Gamma^{-1}/1 Gyr)^{-1}+0.12 for \Gamma^{-1} > 5 Gyr at
+95.4% C.L.. These bounds are robust and widely applicable, because they are
+derived only from gravitational effects and therefore do not rely on the
+details of decay channels or decay products.",0403164v2
+2004-03-10,LISA Measurement of Gravitational Wave Background Anisotropy: Hexadecapole Moment via a Correlation Analysis,"We discuss spatial fluctuations in the gravitational wave background arising
+from unresolved Galactic binary sources, such as close white dwarf binaries,
+due to the fact the galactic binary source distribution is anisotropic. We
+introduce a correlation analysis of the two data streams of the Laser
+Interferometer Space Antenna (LISA) to extract spherical harmonic coefficients,
+in an independent manner, of the hexadecapole moment ($l=4$) related to the
+projected two-dimensional density distribution of the binary source population.
+The proposed technique complements and improves over previous suggestions in
+the literature to measure the gravitational wave background anisotropy based on
+the time modulation of data as LISA orbits around the Sun. Such techniques,
+however, are restricted only to certain combinations of spherical harmonic
+coefficients of the galaxy with no ability to separate them individually. With
+LISA, $m=2,3$ and 4 coefficients of the hexadecapole ($l=4$) can be measured
+with signal-to-noise ratios at the level of 10 and above in a certain
+coordinate system. In addition to the hexadecapole coefficients, when combined
+with the time modulation analysis, the correlation study can also be used, in
+principle, to measure quadrupole coefficients of the binary distribution.",0403259v1
+2004-04-20,Constraints On The Topology Of The Universe From The WMAP First-Year Sky Maps,"We compute the covariance expected between the spherical harmonic
+coefficients $a_{\ell m}$ of the cosmic microwave temperature anisotropy if the
+universe had a compact topology. For fundamental cell size smaller than the
+distance to the decoupling surface, off-diagonal components carry more
+information than the diagonal components (the power spectrum). We use a maximum
+likelihood analysis to compare the Wilkinson Microwave Anisotropy Probe
+first-year data to models with a cubic topology. The data are compatible with
+finite flat topologies with fundamental domain $L > 1.2$ times the distance to
+the decoupling surface at 95% confidence. The WMAP data show reduced power at
+the quadrupole and octopole, but do not show the correlations expected for a
+compact topology and are indistinguishable from infinite models.",0404400v1
+2004-05-03,Constraining Born-Infeld models of dark energy with CMB anisotropies,"We study the CMB constraints on two Dark Energy models described by scalar
+fields with different Lagrangians, namely a Klein-Gordon and a Born-Infeld
+field. The speed of sound of field fluctuations are different in these two
+theories, and therefore the predictions for CMB and structure formation are
+different. Employing the WMAP data on CMB, we make a likelihood analysis on a
+grid of theoretical models. We constrain the parameters of the models and
+compute the probability distribution functions for the equation of state. We
+show that the effect of the different sound speeds affects the low multipoles
+of CMB anisotropies, but is at most marginal for the class of models studied
+here.",0405041v1
+2004-05-10,Primordial magnetic field and non-Gaussianity of the 1-year Wilkinson Microwave Anisotropy Probe (WMAP) data,"Alfven turbulence caused by statistically isotropic and homogeneous
+primordial magnetic field induces correlations in the cosmic microwave
+background anisotropies. The correlations are specifically between spherical
+harmonic modes a_{l-1,m} and a_{l+1,m}. In this paper we approach this issue
+from phase analysis of the CMB maps derived from the WMAP data sets. Using
+circular statistics and return phase mapping we examine phase correlation of
+\Delta l=2 for the primordial non-Gaussianity caused by the Alfven turbulence
+at the epoch of recombination. Our analyses show that such specific features
+from the power-law Alfven turbulence do not contribute significantly in the
+phases of the maps and could not be a source of primordial non-Gaussianity of
+the CMB.",0405181v2
+2004-05-20,B polarization of the CMB from Faraday rotation,"We study the effect of Faraday rotation due to a homogeneous magnetic field
+on the polarization of the cosmic microwave background (CMB). Scalar
+fluctuations give rise only to parity-even E-type polarization of the CMB.
+However in the presence of a magnetic field, a non-vanishing parity-odd B-type
+polarization component is produced through Faraday rotation. We derive the
+exact solution for the E and B modes generated by scalar perturbations
+including the Faraday rotation effect of a uniform magnetic field, and evaluate
+their cross-correlations with temperature anisotropies. We compute the angular
+autocorrelation function of the B-modes in the limit that the Faraday rotation
+is small. We find that primordial magnetic fields of present strength around
+$B_0=10^{-9}$G rotate E-modes into B-modes with amplitude comparable to those
+due to the weak gravitational lensing effect at frequencies around $\nu=30$
+GHz. The strength of B-modes produced by Faraday rotation scales as
+$B_0/\nu^2$. We evaluate also the depolarizing effect of Faraday rotation upon
+the cross correlation between temperature anisotropy and E-type polarization.",0405396v4
+2004-07-27,Theoretical uncertainty in baryon oscillations,"We discuss the systematic uncertainties in the recovery of dark energy
+properties from the use of baryon acoustic oscillations as a standard ruler. We
+demonstrate that while unknown relativistic components in the universe prior to
+recombination would alter the sound speed, the inferences for dark energy from
+low-redshift surveys are unchanged so long as the microwave background
+anisotropies can measure the redshift of matter-radiation equality, which they
+can do to sufficient accuracy. The mismeasurement of the radiation and matter
+densities themselves (as opposed to their ratio) would manifest as an incorrect
+prediction for the Hubble constant at low redshift. In addition, these
+anomalies do produce subtle but detectable features in the microwave
+anisotropies.",0407539v1
+2004-07-30,An Unbiased Measurement of Ho through Cosmic Background Imager Observations of the Sunyaev-Zel'dovich Effect in Nearby Galaxy Clusters,"We present Ho results from Cosmic Background Imager (CBI) observations of the
+Sunyaev-Zel'dovich Effect (SZE) in 7 galaxy clusters, A85, A399, A401, A478,
+A754, A1651, and A2597. These observations are part of a program to study a
+complete, volume-limited sample of low-redshift (z<0.1), X-ray selected
+clusters. Our focus on nearby objects allows us to study a well-defined,
+orientation unbiased sample, minimizing systematic errors due to cluster
+asphericity. We use density models derived from ROSAT imaging data and
+temperature measurements from ASCA and BeppoSAX spectral observations. We
+quantify in detail sources of error in our derivation of Ho, including
+calibration of the CBI data, density and temperature models from the X-ray
+data, Cosmic Microwave Background (CMB) primary anisotropy fluctuations, and
+residuals from radio point source subtraction. From these 7 clusters we obtain
+a result of Ho = 67^{+30}_{-18}, ^{+15}_{-6} km/s/Mpc for an unweighted sample
+average. The respective quoted errors are random and systematic uncertainties
+at 68% confidence. The dominant source of error is confusion from intrinsic
+anisotropy fluctuations.",0408005v1
+2004-08-09,Multiple inflation and the WMAP 'glitches',"Observations of anisotropies in the cosmic microwave background by the
+Wilkinson Microwave Anisotropy Probe suggest the possibility of oscillations in
+the primordial density perturbation. Such deviations from the usually assumed
+scale-free spectrum were predicted in the multiple inflation model wherein
+`flat direction' fields undergo rapid phase transitions due to the breaking of
+supersymmetry by the large vacuum energy driving inflation. This causes sudden
+changes in the mass of the (gravitationally coupled) inflaton and interrupts
+its slow roll. We calculate analytically the resulting modifications to the
+density perturbation and demonstrate how the oscillations arise.",0408138v3
+2004-08-18,Search for Small-Scale Anisotropy of Cosmic Rays above 10^19 eV with HiRes Stereo,"We present the results of a search for small-scale anisotropy in the
+distribution of arrival directions of cosmic rays above 10^19 eV measured in
+stereo by the High Resolution Fly's Eye (HiRes) experiment. Performing an
+autocorrelation scan in energy and angular separation, we find that the
+strongest correlation signal in the HiRes stereo data set recorded between
+December 1999 and January 2004 is consistent with the null hypothesis of
+isotropically distributed arrival directions. These results are compared to
+previous claims of significant small-scale clustering in the AGASA data set.",0408343v1
+2004-08-25,"The spectrum of particles accelerated in relativistic, collisionless shocks","We analytically study diffusive particle acceleration in relativistic,
+collisionless shocks. We find a simple relation between the spectral index s
+and the anisotropy of the momentum distribution along the shock front. Based on
+this relation, we obtain s = (3beta_u - 2beta_u*beta_d^2 + beta_d^3) / (beta_u
+- beta_d) for isotropic diffusion, where beta_u (beta_d) is the upstream
+(downstream) fluid velocity normalized to the speed of light. This result is in
+agreement with previous numerical determinations of s for all (beta_u,beta_d),
+and yields s=38/9 in the ultra-relativistic limit. The spectrum-anisotropy
+connection is useful for testing numerical studies and for constraining
+non-isotropic diffusion results. It implies that the spectrum is highly
+sensitive to the form of the diffusion function for particles travelling along
+the shock front.",0408489v1
+2004-08-30,Anisotropic Distribution of SDSS Satellite Galaxies: Planar (not Polar) Alignment,"The distribution of satellite galaxies relative to isolated host galaxies in
+the Sloan Digital Sky Survey (SDSS) is investigated. Host-satellite systems are
+selected using three different methods, yielding samples of ~3300, ~1600, and
+\~950 satellites. In the plane of the sky, the distributions of all three
+samples show highly significant deviations from circular symmetry (> 99.99%, >
+99.99%, and 99.79% confidence levels, respectively), and the degree of
+anisotropy is a strong function of the projected radius, r_p, at which the
+satellites are found. For r_p < 100 kpc, the SDSS satellites are aligned
+preferentially with the major axes of the hosts. This is in stark contrast to
+the Holmberg effect, in which satellites are aligned with the minor axes of
+host galaxies. The degree of anisotropy in the distribution of the SDSS
+satellites decreases with r_p and is consistent with an isotropic distribution
+at of order the 1-sigma level for 250 kpc < r_p < 500 kpc.",0408559v2
+2004-09-06,The current status of observational cosmology,"Observational cosmology has indeed made very rapid progress in recent years.
+The ability to quantify the universe has largely improved due to observational
+constraints coming from structure formation. The transition to precision
+cosmology has been spearheaded by measurements of the anisotropy in the cosmic
+microwave background (CMB) over the past decade. Observations of the large
+scale structure in the distribution of galaxies, high red-shift supernova, have
+provided the required complementary information. We review the current status
+of cosmological parameter estimates from joint analysis of CMB anisotropy and
+large scale structure (LSS) data. We also sound a note of caution on
+overstating the successes achieved thus far.",0409131v2
+2004-09-15,The Search for Anisotropy in the Arrival Directions of Ultra-High Energy Cosmic Rays Observed by the High Resolution Fly's Eye Detector in Monocular Mode,"The High Resolution Fly's Eye HiRes-I detector has now been in operation in
+monocular mode for over six years. During that time span, HiRes-I has
+accumulated a larger exposure to Ultra-High Energy Cosmic Rays (UHECRs) above
+10^19 eV than any other experiment built to date. This presents an
+unprecedented opportunity to search for anisotropy in the arrival directions of
+UHECRs. We present results of a search for dipole distributions oriented
+towards major astrophysical landmarks and a search for small-scale clustering.
+We conclude that the HiRes-I data set is, in fact, consistent with an isotropic
+source model.",0409377v1
+2004-09-15,First measurements of the polarization of the cosmic microwave background radiation at small angular scales from CAPMAP,"Polarization results from the Cosmic Anisotropy Polarization MAPper (CAPMAP)
+experiment are reported. These are based upon 433 hours, after cuts, observing
+a 2 square degree patch around the North Celestial Pole (NCP) with four 90 GHz
+correlation polarimeters coupled to optics defining $4\arcmin$ beams. The
+E-mode flat bandpower anisotropy within $\ell=940^{+330}_{-300}$ is measured as
+66$^{+69}_{-29} \mu$K$^2$; the 95% Confidence level upper limit for B-mode
+power within $\ell=1050^{+590}_{-520}$ is measured as 38 $\mu$K$^2$.",0409380v3
+2004-09-30,Statistical Imprints of SZ Effects in the Cosmic Microwave Background,"We review several aspects of the Sunyaev-Zel'dovich (SZ) effect associated
+with the large scale baryon distribution and its characteristic signatures in
+the statistics of cosmic microwave background (CMB) anisotropies. We discuss
+(1) the contributions to the angular power spectrum from the thermal and
+kinetic SZ effects, (2) the effect of SZ non-Gaussianities on cosmological
+parameter estimation, and (3) the SZ-induced CMB polarization towards galaxy
+clusters. We also discuss the extent to which recent measurements of small
+angular scale CMB anisotropy can be accounted for by SZ clusters and the
+potential use of SZ polarization towards large samples of galaxy clusters as a
+probe of dark energy parameters.",0410006v1
+2004-10-11,CMB and foregrounds in WMAP first year data,"We perform a blind multi-component analysis of the WMAP 1 year foreground
+cleaned maps using SMICA (Spectral Matching Independent Component Analysis). We
+provide a new estimate of the CMB power spectrum as well as the amplitude of
+the CMB anisotropies across frequency channels. We show that the CMB
+anisotropies are compatible with temperature fluctuations as expected from the
+standard paradigm. The analysis also allows us to identify and separate a weak
+residual galactic emission present significantly in the Q-band outside of the
+Kp2 mask limits, and mainly concentrated at low galactic latitudes. We produce
+a map of this residual component by Wiener filtering using estimated
+parameters. The level of contamination of CMB data by this component is
+compatible with the WMAP team estimation of foreground residual contamination.
+In addition, the multi-component analysis allows us to estimate jointly the
+power spectrum of unresolved point source emission.",0410280v1
+2004-11-10,On the Effects due to a Decaying Cosmological Fluctuation,"We present the initial conditions for a decaying cosmological perturbation
+and study its signatures in the CMB anisotropies and matter power spectra. An
+adiabatic decaying mode in presence of components which are not described as
+perfect fluids (such as collisionless matter) decays slower than in a
+perfect-fluid dominated universe and displays super-Hubble oscillations. By
+including a correlated decaying mode with a red or a scale invariant spectrum,
+the anisotropy pattern shows super-imposed oscillations before the first
+Dopplear peak, while with a blue spectrum the amplitude of the secondary peaks
+relative to the first one and the matter power spectrum can be altered. WMAP
+first year data constrain the decaying to growing ratio of scale invariant
+adiabatic fluctuations at the matter-radiation equality to less than 10%.",0411273v2
+2004-11-15,The Planck Low Frequency Instrument,"Planck is the third generation of mm-wave instruments designed for space
+observations of the cosmic microwave background (CMB) anisotropies within the
+new Cosmic Vision 2020 ESA Science Program. Planck will map the whole sky with
+unprecedented sensitivity, angular resolution, and frequency coverage, and it
+likely leads us to the final comprehension of the CMB anisotropies. The Low
+Frequency Instrument (LFI), operating in the 30-70 GHz range, is one of the two
+instruments onboard Planck satellite, sharing the focal region of a 1.5 meter
+off-axis dual reflector telescope together with the High Frequency Instrument
+(HFI) operating at 100-857 GHz. We present LFI and discuss the major
+instrumental systematic effects that could degrade the measurements and the
+solutions adopted in the design and data analysis phase in order to adequately
+reduce and control them.",0411412v1
+2004-12-21,CMB lensing extraction and primordial non-Gaussianity,"The next generation of CMB experiments should get a better handle on
+cosmological parameters by mapping the weak lensing deflection field, which is
+separable from primary anisotropies thanks to the non-Gaussianity induced by
+lensing. However, the generation of perturbations in the Early Universe also
+produces a level of non-Gaussianity which is known to be small, but can
+contribute to the anisotropy trispectrum at the same level as lensing. In this
+work, we study whether the primordial non-Gaussianity can mask the lensing
+statistics. We concentrate only on the ``temperature quadratic estimator'' of
+lensing, which will be nearly optimal for the Planck satellite, and work in the
+flat-sky approximation. We find that primordial non-Gaussianity contaminates
+the deflection field estimator by roughly (0.1 f_NL)% at large angular scales,
+which represents at most a 10% contribution, not sufficient to threaten lensing
+extraction, but enough to be taken into account.",0412551v1
+2004-12-22,Theoretical tools for CMB physics,"This review presents, in a self-consistent manner, those analytical tools
+that are relevant for the analysis of the physics of CMB anisotropies generated
+in different theoretical models of the early Universe. After introducing the
+physical foundations of the Sachs-Wolfe effect, the origin and evolution of the
+scalar, tensor and vector modes of the geometry is treated in both
+gauge-invariant and gauge-dependent descriptions. Some of the recent progresses
+in the theory of cosmological perturbations are scrutinized with particular
+attention to their implications for the adiabatic and isocurvature paradigms,
+whose description is reviewed both within conventional fluid approaches and
+within the the Einstein-Boltzmann treatment. Open problems and theoretical
+challenges for a unified theory of the early Universe are outlined in light of
+their implications for the generation of large-scale anisotropies in the CMB
+sky and in light of the generation of stochastic backgrounds of relic gravitons
+between few Hz and the GHz.",0412601v3
+2004-12-23,KASCADE: Astrophysical results and tests of hadronic interaction models,"KASCADE is a multi-detector setup to get redundant information on single air
+shower basis. The information is used to perform multiparameter analyses to
+solve the threefold problem of the reconstruction of (i)the unknown primary
+energy, (ii) the primary mass, and (iii) to quantify the characteristics of the
+hadronic interactions in the air-shower development. In this talk recent
+results of the KASCADE data analyses are summarized concerning cosmic ray
+anisotropy studies, determination of flux spectra for different primary mass
+groups, and approaches to test hadronic interaction models. Neither large scale
+anisotropies nor point sources were found in the KASCADE data set. The energy
+spectra of the light element groups result in a knee-like bending and a
+steepening above the knee. The topology of the individual knee positions shows
+a dependency on the primary particle. Though no hadronic interaction model is
+fully able to describe the multi-parameter data of KASCADE consistently, the
+more recent models or improved versions of older models reproduce the data
+better than few years ago.",0412610v1
+2005-01-19,The first turbulent combustion,"The first turbulent combustion arises in a hot big bang cosmological model
+Gibson (2004) where nonlinear exothermic turbulence permitted by quantum
+mechanics, general relativity, multidimensional superstring theory, and fluid
+mechanics cascades from Planck to strong force freeze out scales with gravity
+balancing turbulent inertial-vortex forces. Interactions between Planck scale
+spinning and non-spinning black holes produce high Reynolds number turbulence
+and temperature mixing with huge Reynolds stresses driving the rapid inflation
+of space. Kolmogorovian turbulent temperature patterns are fossilized as
+strong-force exponential inflation stretches them beyond the scale of causal
+connection ct where c is light speed and t is time. Fossil temperature
+turbulence patterns seed nucleosynthesis, and then hydro-gravitational
+structure formation in the plasma epoch, Gibson (1996, 2000). Evidence about
+formation mechanisms is preserved by cosmic microwave background temperature
+anisotropies. CMB spectra indicate hydro-gravitational fragmentation at
+supercluster to galaxy masses in the primordial plasma with space stretched by
+\~10^50. Bershadskii and Sreenivasan (2002, 2003) CMB multi-scaling
+coefficients support a strong turbulence origin for the anisotropies prior to
+the plasma epoch.",0501416v2
+2005-02-21,Reionization History from Coupled CMB/21cm Line Data,"We study CMB secondary anisotropies produced by inhomogeneous reionization by
+means of cosmological simulations coupled with the radiative transfer code
+CRASH. The reionization history is consistent with the WMAP Thomson optical
+depth determination. We find that the signal arising from this process
+dominates over the primary CMB component for l > 4000 and reaches a maximum
+amplitude of l(l+1)C_l/2\pi ~ 1.6 x 10^{-13} on arcmin scale, i.e. l as large
+as several thousands. We then cross-correlate secondary CMB anisotropy maps
+with neutral hydrogen 21cm line emission fluctuations obtained from the same
+simulations. The two signals are highly anti-correlated on angular scales
+corresponding to the typical size of HII regions (including overlapping) at the
+21cm map redshift. We show how the CMB/21cm cross-correlation can be used to:
+(a) study the nature of the reionization sources, (b) reconstruct the cosmic
+reionization history, (c) infer the mean cosmic ionization level at any
+redshift. We discuss the feasibility of the proposed experiment with
+forthcoming facilities.",0502419v1
+2005-02-25,Density scaling and anisotropy in supersonic MHD turbulence,"We study the statistics of density for supersonic turbulence in a medium with
+magnetic pressure larger than the gaseous pressure. This study is motivated by
+molecular cloud research. Our simulations exhibit clumpy density structures,
+which contrast increases with the Mach number. At 10 Machs densities of some
+clumps are three orders of magnitude higher than the mean density. These clumps
+give rise to flat and approximately isotropic density spectrum corresponding to
+the random distribution of clumps in space. We claim that the clumps originate
+from our random, isotropic turbulence driving. When the contribution from those
+clumps is suppressed by studying logarithm of density, the density statistics
+exhibit scale-dependent anisotropy consistent with the models where density
+structures arise from shearing by Alfv\'en waves. It is noteworthy that
+originally such models were advocated for the case of low-Mach, nearly
+incompressible turbulence.",0502547v1
+2005-03-05,Signatures of Cosmic Strings in the Cosmic Microwave Background,"We report a search for signatures of cosmic strings in the the Cosmic
+Microwave Background data from the Wilkinson Microwave Anisotropy Probe. We
+used a digital filter designed to search for individual cosmic strings and
+found no evidence for them in the WMAP CMB anisotropies to a level of $\Delta
+T/T \sim 0.29$ mK. This corresponds to an absence of cosmic strings with $ G\mu
+\ga 1.07 \times 10^{-5}$ for strings moving with velocity $v = c/\sqrt{2}$.
+Unlike previous work, this limit does not depend on an assumed string
+abundance. We have searched the WMAP data for evidence of a cosmic string
+recently reported as the CSL-1 object, and found an ``edge'' with 2$\sigma$
+significance. However, if this edge is real and produced by a cosmic string, it
+would have to move at velocity $\ga$ 0.94c. We also present preliminary limits
+on the CMB data that will be returned by the PLANCK satellite for comparison.
+With the available information on the PLANCK satellite, we calculated that it
+would be twice as sensitive to cosmic strings as WMAP.",0503120v1
+2005-05-06,Large-Scale Sidereal Anisotropy of Galactic Cosmic-Ray Intensity Observed by the Tibet Air Shower Array,"We present the large-scale sidereal anisotropy ofgalactic cosmic-ray
+intensity in the multi-TeV region observed with the Tibet-IIIair shower array
+during the period from 1999 through 2003. The sidereal daily variation of
+cosmic rays observed in this experiment shows an excess of relative intensity
+around $4\sim7 $ hours local sidereal time, as well as a deficit around 12
+hours local sidereal time. While the amplitude of the excess is not significant
+when averaged over all declinations, the excess in individual declinaton bands
+becomes larger and clearer as the viewing direction moves toward the south. The
+maximum phase of the excess intensity changes from $\sim$7 at the northern
+hemisphere to $\sim$4 hours at the equatorial region. We also show that both
+the amplitude and the phase of the first harmonic vector of the daily variation
+are remarkably independent of primary energy in the multi-TeV region. This is
+the first result determining the energy and declination dependences of the full
+24-hour profiles of the sidereal daily variation in the multi-TeV region with a
+single air shower experiment.",0505114v1
+2005-06-24,Large-Scale Anisotropy of EGRET Gamma Ray Sources,"In the course of its operation, the EGRET experiment detected high-energy
+gamma ray sources at energies above 100 MeV over the whole sky. In this
+communication, we search for large-scale anisotropy patterns among the
+catalogued EGRET sources using an expansion in spherical harmonics, accounting
+for EGRET's highly non-uniform exposure. We find significant excess in the
+quadrupole and octopole moments. This is consistent with the hypothesis that,
+in addition to the galactic plane, a second mid-latitude (5^{\circ} < |b| <
+30^{\circ}) population, perhaps associated with the Gould belt, contributes to
+the gamma ray flux above 100 MeV.",0506598v1
+2005-08-05,Scalelengths in Dark Matter Halos,"We investigate a hypothesis regarding the origin of the scalelength in halos
+formed in cosmological N-body simulations. This hypothesis can be viewed as an
+extension of an earlier idea put forth by Merritt and Aguilar. Our findings
+suggest that a phenomenon related to the radial orbit instability is present in
+such halos and is responsible for density profile shapes. This instability sets
+a scalelength at which the velocity dispersion distribution changes rapidly
+from isotropic to radially anisotropic. This scalelength is reflected in the
+density distribution as the radius at which the density profile changes slope.
+We have tested the idea that radially dependent velocity dispersion anisotropy
+leads to a break in density profile shape by manipulating the input of a
+semi-analytic model to imitate the velocity structure imposed by the radial
+orbit instability. Without such manipulation, halos formed are approximated by
+single power-law density profiles and isotropic velocity distributions. Halos
+formed with altered inputs display density distributions featuring scalelengths
+and anisotropy profiles similar to those seen in cosmological N-body
+simulations.",0508160v1
+2005-08-30,Velocity moments of dark matter haloes,"Using cosmological N-body simulations we study the line-of-sight velocity
+distribution of dark matter haloes focusing on the lowest-order even moments,
+dispersion and kurtosis, and their application to estimate the mass profiles of
+cosmological structures. For each of the ten massive haloes selected from the
+simulation box we determine the virial mass, concentration and the anisotropy
+parameter. In order to emulate observations from each halo we choose randomly
+300 particles and project their velocities and positions along the line of
+sight and on the surface of the sky, respectively. After removing interlopers
+we calculate the profiles of the line-of-sight velocity moments and fit them
+with the solutions of the Jeans equations. The estimates of virial mass,
+concentration parameter and velocity anisotropy obtained in this way are in
+good agreement with the values found from the full 3D analysis.",0508639v1
+2005-09-12,Spontaneous Isotropy Breaking: A Mechanism for CMB Multipole Alignments,"We introduce a class of models in which statistical isotropy is broken
+spontaneously in the CMB by a non-linear response to long-wavelength
+fluctuations in a mediating field. These fluctuations appear as a gradient
+locally and pick out a single preferred direction. The non-linear response
+imprints this direction in a range of multipole moments. We consider two
+manifestations of isotropy breaking: additive contributions and multiplicative
+modulation of the intrinsic anisotropy. Since WMAP exhibits an alignment of
+power deficits, an additive contribution is less likely to produce the observed
+alignments than the usual isotropic fluctuations, a fact which we illustrate
+with an explicit cosmological model of long-wavelength quintessence
+fluctuations. This problem applies to other models involving foregrounds or
+background anisotropy that seek to restore power to the CMB. Additive models
+that account directly for the observed power exacerbate the low power of the
+intrinsic fluctuations. Multiplicative models can overcome these difficulties.
+We construct a proof of principle model that significantly improves the
+likelihood and generates stronger alignments than WMAP in 30-45% of
+realizations.",0509301v1
+2005-09-15,Revisiting the (V/sigma)-epsilon anisotropy diagram of early-type galaxies using integral-field kinematics,"We use integral-field observation of the stellar kinematics obtained with
+SAURON in combination with Schwarzschild dynamical models to revisit our
+understanding of the classic (V/sigma)-epsilon anisotropy diagram of early-type
+galaxies.",0509470v1
+2005-09-25,Prediction of the Virgo axis anisotropy: CMB radiation illuminates the nature of things,"Recent findings of the anisotropy in the Cosmic Microwave Background (CMB)
+radiation are confusing for standard cosmology. Remarkably, this fact has been
+predicted several years ago in the framework of our model of the physical
+world. Moreover, in exact agreement with our prediction the CMB has a preferred
+direction towards the Virgo Cluster. The transpired structure of the CMB shows
+workings of the suggested model of the physical world. Comprising the
+information processes of Nature, this model presents a high-tech version of the
+previous low-tech developments for mechanical ether and quantum vacuum. In the
+current model, the phenomenon of Life turns up as a collective effect on the
+""Internet of the Physical Universe"" using DNA structures for access codes. Most
+convincingly, this construction points to a harmful analogy with so-called
+""identity theft"" - improper manipulations with DNA of individual organisms can
+destroy these organisms from a remote location without any physical contact.
+Appearing incredible, such a possibility creates a superlative Experimentum
+Crucis. In a broad sense, this surmised biological effect is intimately related
+to the cosmological prediction of the structurization of the CMB, but it is
+more compelling.",0509743v1
+2005-10-14,Charting the New Frontier of the Cosmic Microwave Background Polarization,"The anisotropies of the cosmic microwave background are a gold mine for
+cosmology and fundamental physics. ESA's Planck satellite should soon extract
+all information from the temperature vein but will be limited concerning the
+measurement of the degree of polarization of the anisotropies. This
+polarization information allows new independent tests of the standard
+cosmological paradigm, improves knowledge of cosmological parameters and last
+but not least is the best window available for constraining the physics of the
+very early universe, particularly the expected background of primordial
+gravitational waves. But exploiting this vein will be a challenge, since the
+sensitivity required is {\em at least} 10 times better than what Planck might
+achieve at best, with the necessary matching level of control of all
+systematics effects, both instrumental and astrophysical (foregrounds). We here
+recall the cosmological context and the case for CMB polarization studies. We
+also briefly introduce the SAMPAN project, a design study at CNES that aims at
+detecting the primoridal gravitational wave background for a tensor to scalar
+ratio T/S as small as 0.001.",0510423v1
+2005-11-24,Distribution function of the dark matter,"There is good evidence from N-body simulations that the velocity distribution
+in the outer parts of halos is radially anisotropic, with the kinetic energy in
+the radial direction roughly equal to the sum of that in the two tangential
+directions. We provide a simple algorithm to generate such cosmologically
+important distribution functions. Introducing r_E(E), the radius of the largest
+orbit of a particle with energy E, we show how to write down almost trivially a
+distribution function of the form f(E,L)=g(r_E)/L for any spherical model --
+including the NFW profile. We in addition give the generic form of the
+distribution function for any model with a local density power-law index and
+anisotropy parameter, and provide limiting forms appropriate for the central
+parts and envelopes of dark matter halos. From those, we argue that, regardless
+of the anisotropy, the density fall-off at large radii must evolve to 1/r^4 or
+steeper ultimately.",0511687v2
+2005-12-23,Local virial relation and velocity anisotropy in self-gravitating system,"We investigate the merging process in N-body self-gravitating system from the
+viewpoints of the local virial relation which is the relation between the local
+kinetic energy and the local potential. We compare both the density profile and
+the phase space density profile in cosmological simulations with the critical
+solutions of collisionless static state satisfying the local virial (LV)
+relation. We got the results that the critical solution can explain the
+characteristic density profile with the appropriate value of anisotropy
+parameter $\beta \sim 0.5$. It can also explain the power law of the phase
+space density profile in the outer part of a bound state. However, it fails in
+explaining the central low temperature part which is connected to the scale
+invariant phase space density. It can be well fitted to the critical solution
+with the higher value of$\beta \sim 0.75$. These results indicate that the LV
+relation is not compatible with the scale invariant phase space density in
+cosmological simulation.",0512587v1
+2006-01-16,Constraints on the coupled quintessence from cosmic microwave background anisotropy and matter power spectrum,"We discuss the evolution of linear perturbations in a quintessence model in
+which the scalar field is non-minimally coupled to cold dark matter. We
+consider the effects of this coupling on both cosmic microwave background
+temperature anisotropies and matter perturbations. Due to the modification of
+the scale of cold dark matter as $\rho_{c} = \rho_{c}^{(0)} a^{-3 + \xi}$, we
+can shift the turnover in the matter power spectrum even without changing the
+present energy densities of matter and radiation. This can be used to constrain
+the strength of the coupling. We find that the phenomenology of this model is
+consistent with current observations up to the coupling power $n_{c} \leq 0.01$
+while adopting the current parameters measured by WMAP. Upcoming cosmic
+microwave background observations continuing to focus on resolving the higher
+peaks may put strong constraints on the strength of the coupling.",0601333v1
+2006-01-25,Cosmic Microwave Background Polarization,"Cosmic microwave background (CMB) anisotropy is our richest source of
+cosmological information; the standard cosmological model was largely
+established thanks to study of the temperature anisotropies. By the end of the
+decade, the Planck satellite will close this important chapter and move us
+deeper into the new frontier of polarization measurements. Numerous
+ground--based and balloon--borne experiments are already forging into this new
+territory. Besides providing new and independent information on the primordial
+density perturbations and cosmological parameters, polarization measurements
+offer the potential to detect primordial gravity waves, constrain dark energy
+and measure the neutrino mass scale. A vigorous experimental program is
+underway worldwide and heading towards a new satellite mission dedicated to CMB
+polarization.",0601576v3
+2006-01-26,Small scale contributions to CMB: A coherent analysis,"We reanalyse Cosmic Microwave Background data from experiments probing both
+large and small scales. We assume that measured anisotropies are due not only
+to primary fluctuations but also, especially at small scales, to secondary
+effects (namely the Sunyaev-Zel'dovich effect) and possible point source
+contaminations. We first consider primary and secondary anisotropies only. For
+the first time in such analyses, the cosmological dependence of secondary
+fluctuations is fully taken into account. We show in that case that a higher
+value of the normalisation $\sigma\_8$ is preferred, as found by previous
+studies, but also higher values of the optical depth $\tau$ and power spectrum
+index $n\_s$ are needed. In the second part of our analysis, we further include
+possible contaminations from unresolved and unremoved point sources. Under
+these considerations, we discuss the effects on the cosmological parameters. We
+further obtain the best combination of relative contributions of the three
+kinds of sources to the measured microwave power on small scales at each
+frequency. Our method allows us to simultaneously obtain cosmological
+parameters and explain the so-called small scale power excess in a consistent
+way.",0601597v1
+2006-02-06,Advanced Topics in Cosmology: A Pedagogical Introduction,"These lecture notes provide a concise, rapid and pedagogical introduction to
+several advanced topics in contemporary cosmology. The discussion of thermal
+history of the universe, linear perturbation theory, theory of CMBR temperature
+anisotropies and the inflationary generation of perturbation are presented in a
+manner accessible to someone who has done a first course in cosmology. The
+discussion of dark energy is more research oriented and reflects the personal
+bias of the author. Contents: (I) The cosmological paradigm and Friedmann model
+(II) Thermal history of the universe (III) Structure formation and linear
+perturbation theories (IV) Perturbations in dark matter and radiation (V)
+Transfer function for matter perturbations (VI) Temperature anisotropies of
+CMBR (VII) Generation of initial perturbations from inflation (VIII) The dark
+energy.",0602117v1
+2006-02-13,The shape of high order correlation functions in CMB anisotropy maps,"We present a phenomenological investigation of non-Gaussian effects that
+could be seen on CMB temperature maps. Explicit expressions for the temperature
+correlation functions are given for different types of primordial mode
+couplings. We argue that a simplified description of the radial transfer
+function for the temperature anisotropies allows to get insights into the
+general properties of the bi and tri-spectra. The accuracy of these results is
+explored together with the use of the small scale approximation to get explicit
+expressions of high order spectra. The bi-spectrum is found to have alternate
+signs for the successive acoustic peaks. Sign patterns for the trispectra are
+more complicated and depend specifically on the type of metric couplings. Local
+primordial couplings are found to give patterns that are different from those
+expected from weak lensing effects.",0602276v1
+2006-02-21,Long range correlation in cosmic microwave background radiation,"We investigate the statistical anisotropy and Gaussianity of temperature
+fluctuations of Cosmic Microwave Background radiation (CMB) data from {\it
+Wilkinson Microwave Anisotropy Probe} survey, using the multifractal detrended
+fluctuation analysis, rescaled range and scaled windowed variance methods. The
+multifractal detrended fluctuation analysis shows that CMB fluctuations has a
+long range correlation function with a multifractal behavior. By comparing the
+shuffled and surrogate series of CMB data, we conclude that the multifractality
+nature of temperature fluctuation of CMB is mainly due to the long-range
+correlations and the map is consistent with a Gaussian distribution.",0602461v2
+2006-03-14,Global universe anisotropy probed by the alignment of structures in the cosmic microwave background,"We question the global universe isotropy by probing the alignment of local
+structures in the cosmic microwave background (CMB) radiation. The original
+method proposed relies on a steerable wavelet decomposition of the CMB signal
+on the sphere. The analysis of the first-year WMAP data identifies a mean
+preferred plane with a normal direction close to the CMB dipole axis, and a
+mean preferred direction in this plane, very close to the ecliptic poles axis.
+Previous statistical anisotropy results are thereby synthesized, but further
+analyses are still required to establish their origin.",0603367v1
+2006-03-23,"Probing Dynamics of Dark Energy with Supernova, Galaxy Clustering and the Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations","Using the Markov chain Monte Carlo (MCMC) method we perform a global analysis
+constraining the dynamics of dark energy in light of the supernova (Riess
+""Gold"" samples), galaxy clustering (SDSS 3D power spectra and SDSS lyman-\alpha
+forest information) and the latest three-year Wilkinson Microwave Anisotropy
+Probe (WMAP) observations. We have allowed the dark energy equation of state to
+get across -1 and pay particular attention to the effects when incorrectly
+neglecting dark energy perturbations. We find the parameter space of dynamical
+dark energy is now well constrained and neglecting dark energy perturbations
+will make the parameter space significantly smaller. Dynamical dark energy
+model where the equation of state crosses -1 is mildly favored and the standard
+\LambdaCDM model is still a good fit to the current data.",0603621v1
+2006-04-06,On vector mode contribution to CMB temperature and polarization from local strings,"In a recent publication, we used the data from WMAP and SDSS to constrain the
+primordial perturbations and to predict the B-mode polarization sourced by
+cosmic string networks. We have been alerted by A. Slosar to the existence of
+errors in the code we used to calculate the Cosmic Microwave Background
+anisotropies from cosmic strings. Correcting the errors leads to a significant
+increase in the vector mode contribution to the CMB temperature and
+polarization anisotropies as well as an overall renormalization of the various
+string spectra. In these notes we explain the nature of the errors and discuss
+their implications for previously published constraints on cosmic strings based
+on this code. The chief change in our results is that our derived limit for the
+cosmic string tension is strengthened: G\mu < 1.8 (2.7) * 10^{-7} at 68 (95)%
+confidence. We also note that the newly-enhanced vector mode contribution
+produces a greatly-increased amplitude for B-mode polarization in the CMB which
+could exceed the B-mode power produced by the lensing of primordial E-mode
+polarization into B-mode polarization.",0604141v1
+2006-04-06,"Amplified Doppler shift observed in diffraction images as function of the COBE ""ether drift"" direction","We report results on an ``one-way light path'' laser diffraction experiment
+as a function of the laser beam alignment relative to the Earth's velocity
+vector obtained by COBE measurements of the Doppler shift in the cosmic
+microwave background radiation (CMBR). An amplified Doppler shift is observed
+in the diffraction images, and the effect is compatible with a ``dipole'' speed
+of light anisotropy due to Earth's motion relative to the ``CMBR rest frame'',
+with an amplitude of $\delta c/\bar{c}=0.00123$. This amplitude coincides with
+the value of the dipole temperature anisotropy $\delta T/\bar{T}=0.00123$ of
+the CMBR obtained by COBE. Our results point out that it is not possible to
+neglect the preferred frame imposed by the cosmology and they are well
+described by the Ether Gauge Theory (an extension of the Lorentz's ether
+theory) and it satisfies the cosmological time boundary condition.",0604145v1
+2006-04-13,On the status of superheavy dark matter,"Superheavy particles are a natural candidate for the dark matter in the
+universe and our galaxy, because they are produced generically during inflation
+in cosmologically interesting amounts. The most attractive model for the origin
+of superheavy dark matter (SHDM) is gravitational production at the end of
+inflation. The observed cosmological density of dark matter determines the mass
+of the SHDM particle as $m_X=$(a few)$\:\times 10^{13}$ GeV, promoting it to a
+natural candidate for the source of the observed ultra-high energy cosmic rays
+(UHECR). After a review of the theoretical aspects of SHDM, we up-date its
+predictions for UHECR observations: no GZK cutoff, flat energy spectrum with
+$dN/dE\approx 1/E^{1.9}$, photon dominance and galactic anisotropy. We analyze
+the existing data and conclude that SDHM as explanation for the observed UHECRs
+is at present disfavored but not yet excluded. We calculate the anisotropy
+relevant for future Auger observations that should be the conclusive test for
+this model. Finally, we emphasize that negative results of searches for SHDM in
+UHECR do not disfavor SHDM as a dark matter candidate. Therefore, UHECRs
+produced by SHDM decays and with the signatures as described should be searched
+for in the future as subdominant effect.",0604311v1
+2006-05-18,The Compton-Getting effect on ultra-high energy cosmic rays of cosmological origin,"Deviations from isotropy have been a key tool to identify the origin and the
+primary type of cosmic rays at low energies. We suggest that the
+Compton-Getting effect can play a similar role at ultra-high energies: If at
+these energies the cosmic ray flux is dominated by sources at cosmological
+distances, then the movement of the Sun relative to the cosmic microwave
+background frame induces a dipole anisotropy at the 0.6% level. The energy
+dependence and the orientation of this anisotropy provide important information
+about the transition between galactic and extragalactic cosmic rays, the charge
+of the cosmic ray primaries, the galactic magnetic field and, at the highest
+energies, the energy-loss horizon of cosmic rays. A 3-sigma detection of this
+effect requires around 10^6 events in the considered energy range and is thus
+challenging but not impossible with present detectors. As a corollary we note
+that the Compton-Getting effect allows one also to constrain the fraction of
+the diffuse gamma-ray background emitted by sources at cosmological distance,
+with promising detection possibilities for the GLAST satellite.",0605462v2
+2006-07-04,Shear Recovery Accuracy in Weak Lensing Analysis with Elliptical Gauss-Laguerre Method,"We implement the Elliptical Gauss-Laguerre (EGL) galaxy-shape measurement
+method proposed by Bernstein & Jarvis (2002) and quantify the shear recovery
+accuracy in weak lensing analysis. This method uses a deconvolution fitting
+scheme to remove the effects of the point-spread function (PSF). The test
+simulates >10^7 noisy galaxy images convolved with anisotropic PSFs, and
+attempts to recover an input shear. The tests are designed to be immune to
+shape noise, selection biases, and crowding. The systematic error in shear
+recovery is divided into two classes, calibration (multiplicative) and
+additive, with the latter arising from PSF anisotropy. At S/N > 50, the
+deconvolution method measures the galaxy shape and input shear to ~ 1%
+multiplicative accuracy, and suppresses > 99% of the PSF anisotropy. These
+systematic errors increase to ~ 4% for the worst conditions, with poorly
+resolved galaxies at S/N ~ 20. The EGL weak lensing analysis has the best
+demonstrated accuracy to date, sufficient for the next generation of weak
+lensing surveys.",0607062v1
+2006-07-08,Ellipticity in Cosmic Microwave Background as a Tracer of Large-Scale Universe,"Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data confirm the
+ellipticity of anisotropies of Cosmic Microwave Background (CMB) maps, found
+previously for Boomerang and WMAP 1-year high sensitivity maps. The low noise
+level of the WMAP latter data enable also to show that, the ellipticity is a
+property not described by the conventional cosmological model fitting the power
+spectrum of CMB. As a large scale anomaly, the ellipticity characteristics are
+consistent with the effect of geodesics mixing occurring in hyperbolic
+Universe. Its relation to other large scale effects, i.e. to suppressed low
+multipoles, as well as to dark energy if the latter is due to vacuum
+fluctuations, is then an arising issue.",0607160v2
+2006-07-12,Cosmology with CMB anisotropy,"Measurements of CMB anisotropy and, more recently, polarization have played a
+very important role allowing precise determination of various parameters of the
+`standard' cosmological model. The expectation of the paradigm of inflation and
+the generic prediction of the simplest realization of inflationary scenario in
+the early universe have also been established -- `acausally' correlated initial
+perturbations in a flat, statistically isotropic universe, adiabatic nature of
+primordial density perturbations. Direct evidence for gravitational instability
+mechanism for structure formation from primordial perturbations has been
+established. In the next decade, future experiments promise to strengthen these
+deductions and uncover the remaining crucial signature of inflation -- the
+primordial gravitational wave background.",0607255v1
+2006-07-17,Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory,"Data from the Pierre Auger Observatory are analyzed to search for
+anisotropies near the direction of the Galactic Centre at EeV energies. The
+exposure of the surface array in this part of the sky is already significantly
+larger than that of the fore-runner experiments. Our results do not support
+previous findings of localized excesses in the AGASA and SUGAR data. We set an
+upper bound on a point-like flux of cosmic rays arriving from the Galactic
+Centre which excludes several scenarios predicting sources of EeV neutrons from
+Sagittarius $A$. Also the events detected simultaneously by the surface and
+fluorescence detectors (the `hybrid' data set), which have better pointing
+accuracy but are less numerous than those of the surface array alone, do not
+show any significant localized excess from this direction.",0607382v3
+2006-07-26,Space-time Evolution and CMB Anisotropies from Quantum Gravity,"We propose an evolutional scenario of the universe which starts from quantum
+states with conformal invariance, passing through the inflationary era, and
+then makes transition to the conventional Einstein space-time. The space-time
+dynamics is derived from the renormalizable higher-derivative quantum gravity
+developed on the basis of a renormalizable conformal gravity in four
+dimensions. Based on the linear perturbation theory in the inflationary
+background, we simulate evolutions of gravitational scalar, vector and tensor
+perturbations, and evaluate the spectra at the transition point located at the
+beginning of the big bang. The obtained spectra cover the range of the
+primordial spectra for explaining the tiny anisotropy in the homogeneous CMB.",0607586v3
+2006-08-18,CMB Anomalies from Relic Anisotropy,"Most of the analysis of the Cosmic Microwave Background relies on the
+assumption of statistical isotropy. However, given some recent evidence
+pointing against isotropy, as for instance the observed alignment of different
+multipoles on large scales, it is worth testing this assumption against the
+increasing amount of available data. As a pivot model, we assume that the
+spectrum of the primordial perturbations depends also on their directionality
+(rather than just on the magnitude of their momentum, as in the standard case).
+We explicitly compute the correlation matrix for the temperature anisotropies
+in the simpler case in which there is a residual isotropy between two spatial
+directions. As a concrete example, we consider a different initial expansion
+rate along one direction, and the following isotropization which takes place
+during inflation. Depending on the amount of inflation, this can lead to broken
+statistical isotropy on the largest observable scales.",0608405v2
+2006-08-23,Intracluster Medium through three years of WMAP,"Wilkinson Microwave Anisotropy Probe (WMAP) has provided us with the yet
+highest resolution all-sky maps of the Cosmic Microwave Background. As a result
+of thermal Sunyaev-Zel'dovich effect, clusters of galaxies are imprinted as
+tiny, poorly resolved dips on top of primary CMB anisotropies in these maps.
+Here, I describe different efforts to extract the physics of Intracluster
+Medium (ICM) from the sea of primary CMB, through combining WMAP with
+low-redshift galaxy or X-ray cluster surveys. This finally culminates at a mean
+(universal) ICM pressure profile, which is for the first time directly
+constrained from WMAP 3yr maps, and leads to interesting constraints on the ICM
+baryonic budget.",0608503v1
+2006-09-19,PAPPA: Primordial Anisotropy Polarization Pathfinder Array,"The Primordial Anisotropy Polarization Pathfinder Array (PAPPA) is a
+balloon-based instrument to measure the polarization of the cosmic microwave
+background and search for the signal from gravity waves excited during an
+inflationary epoch in the early universe. PAPPA will survey a 20 x 20 deg patch
+at the North Celestial Pole using 32 pixels in 3 passbands centered at 89, 212,
+and 302 GHz. Each pixel uses MEMS switches in a superconducting microstrip
+transmission line to combine the phase modulation techniques used in radio
+astronomy with the sensitivity of transition-edge superconducting bolometers.
+Each switched circuit modulates the incident polarization on a single detector,
+allowing nearly instantaneous characterization of the Stokes I, Q, and U
+parameters. We describe the instrument design and status.",0609546v1
+2006-10-04,CMB Anisotropies at Second-Order II: Analytical Approach,"We provide an analytical approach to the second-order Cosmic Microwave
+Background (CMB) anisotropies generated by the non-linear dynamics taking place
+at last scattering. We study the acoustic oscillations of the photon-baryon
+fluid in the tight coupling limit and we extend at second-order the Meszaros
+effect. We allow for a generic set of initial conditions due to primordial
+non-Gaussianity and we compute all the additional contributions arising at
+recombination. Our results are useful to provide the full second-order
+radiation transfer function at all scales necessary for establishing the level
+of non-Gaussianity in the CMB.",0610110v2
+2006-10-17,Cosmic microwave background limits on spatially homogeneous cosmological models with dark energy,"We investigate the effect of dark energy on the limits on the shear
+anisotropy in spatially homogeneous Bianchi cosmological models obtained from
+measurements of the temperature anisotropies in the cosmic microwave
+background. We shall primarily assume that the dark energy is modelled by a
+cosmological constant. In general, we find that there are tighter bounds on the
+shear than in models with no cosmological constant, although the limits are
+(Bianchi) model dependent. In addition, there are special spatially homogeneous
+cosmological models whose rate of expansion is highly anisotropic, but whose
+cosmic microwave background temperature is measured to be exactly isotropic at
+one instant of time.",0610498v2
+2006-11-08,Observational constraints on a decaying cosmological term,"We investigate the evolution of a universe with a decaying cosmological term
+(vacuum energy) that is assumed to be a function of the scale factor. In this
+model, while the cosmological term increases to the early universe, the
+radiation energy density is lower than the model with the cosmological
+""constant"". We find that the effects of the decaying cosmological term on the
+expansion rate at the redshift z<2 is negligible.
+  However, the decrease in the radiation density affects on the thermal history
+of the universe; e.g. the photon decoupling occurs at higher $z$ compared to
+the case of the standard \Lambda CDM model. As a consequence, a decaying
+cosmological term affects on the cosmic microwave background anisotropy. We
+show the angular power spectrum in D\Lambda CDM model and compare with the
+Wilkinson Microwave Anisotropy Probe (WMAP) data.",0611258v2
+2006-11-28,Constraining the Variation of G by Cosmic Microwave Background Anisotropies,"We use the Cosmic Microwave Background Anisotropies (CMBA) power spectra to
+constrain the cosmological variation of gravitational constant G. It is found
+that the sensitivity of CMBA to the variation of G is enhanced when G is
+required to converge to its present value. The variations of G from the CMB
+decoupling epoch z ~ 1000 to the present time are modelled by a step function
+and a linear function of scale factor $a$ respectively, and the corresponding
+95% confidence intervals for G/G_0 are [0.95, 1.05] and [0.89, 1.13], G_0 being
+the present value. The CMBA constraint is unique in the sense that it entails
+the range of redshift from z \approx 1000 to 0.",0611851v2
+2007-02-06,"Primordial helium recombination III: Thomson scattering, isotope shifts, and cumulative results","Upcoming precision measurements of the temperature anisotropy of the cosmic
+microwave background (CMB) at high multipoles will need to be complemented by a
+more complete understanding of recombination, which determines the damping of
+anisotropies on these scales. This is the third in a series of papers
+describing an accurate theory of HeI and HeII recombination. Here we describe
+the effect of Thomson scattering, the $^3$He isotope shift, the contribution of
+rare decays, collisional processes, and peculiar motion. These effects are
+found to be negligible: Thomson and $^3$He scattering modify the free electron
+fraction $x_e$ at the level of several $\times 10^{-4}$. The uncertainty in the
+$2^3P^o-1^1S$ rate is significant, and for conservative estimates gives
+uncertainties in $x_e$ of order $10^{-3}$. We describe several convergence
+tests for the atomic level code and its inputs, derive an overall $C_\ell$
+error budget, and relate shifts in $x_e(z)$ to the changes in $C_\ell$, which
+are at the level of 0.5% at $\ell =3000$. Finally, we summarize the main
+corrections developed thus far. The remaining uncertainty from known effects is
+$\sim 0.3%$ in $x_e$.",0702145v2
+2007-02-13,On using the CMB shift parameter in tests of models of dark energy,"The so-called shift parameter is related to the position of the first
+acoustic peak in the power spectrum anisotropies of the cosmic microwave
+background (CMB) anisotropies. It is an often used quantity in simple tests of
+dark energy models. However, the shift parameter is not directly measurable
+from the cosmic microwave background, and its value is usually derived from the
+data assuming a spatially flat cosmology with dark matter and a cosmological
+constant. Our aim in this paper is to evaluate the effectiveness of the shift
+parameter as a constraint on dark energy models, and the potential pitfalls in
+using it as a test of non-standard models of dark energy. By comparing to full
+CMB fits, we show that combining the shift parameter with the position of the
+first acoustic peak in the CMB power spectrum improves the accuracy of the test
+considerably.",0702343v1
+2007-02-14,"Possible extensions of the standard cosmological model: anisotropy, rotation, and magnetic field","We show that the difference between the theoretically expected and measured
+by WMAP amplitude of the quadrupole fluctuations of CMB can be related to the
+impact of the anisotropic curvature of the homogeneous universe dominated by
+the dark energy. In such universe the matter expansion becomes practically
+isotropic just after the period of inflation and only at small redshifts the
+anisotropic expansion is generated again by the small curvature $\Omega_K=1-
+\Omega_m- \Omega_\Lambda \leq 10^{-4}$. For such models the possible deviations
+from the parameters derived for the standard cosmological model are evidently
+negligible but the correlations of large scale perturbations and distortions of
+their Gaussianity are possible. Such models are also compatible with existence
+of a homogeneous magnetic field and matter rotation which contribute to the low
+$\ell$ anisotropy and can be considered as ``hidden parameters'' of the model.
+Their influence can be observed as, for example, special correlations of small
+scale fluctuations and the Faraday rotation of the CMB and radiation of the
+farthest quasars. However, both the magnetic field and matter rotation require
+also modifications of the simple models of isotropic inflation and they change
+the evolutionary history of the early Universe.",0702381v2
+2007-02-22,Temperature Anisotropy in a Shocked Plasma: Mirror-Mode Instabilities in the Heliosheath,"We show that temperature anisotropies induced at a shock can account for
+interplanetary and planetary bow shock observations. Shocked plasma with
+enhanced plasma beta is preferentially unstable to the mirror mode instability
+downstream of a quasi-perpendicular shock and to the firehose instability
+downstream of a quasi-parallel shock, consistent with magnetic fluctuations
+observed downstream of a large variety of shocks. Our theoretical analysis of
+the solar wind termination shock suggests that the magnetic holes observed by
+Voyager 1 in the heliosheath are produced by the mirror mode instability. The
+results are also of astrophysical interest, providing an energy source for
+plasma heating.",0702599v1
+2007-02-28,Looking for signs of Anisotropic Cosmological Expansion in the High-z Supernova data,"Several problematical epochs in cosmology, including the recent period of
+structure formation (and acceleration), require us to understand cosmic
+evolution during times when the basis of FRW expansion, the cosmological
+principle, does not completely hold true. We consider that the breakdown of
+isotropy and homogeneity at such times may be an important key towards
+understanding cosmic evolution. To study this, we examine fluctuations in the
+high-z supernova data to search for signs of large-scale anisotropy in the
+Hubble expansion. Using a cosmological-model-independent statistical analysis,
+we find mild evidence of real anisotropy in various circumstances. We consider
+the significance of these results, and the importance of further searches for
+violations of the cosmological principle.",0702730v1
+2007-03-02,Dark-energy constraints with ALMA polarization measurements,"The Cosmic Microwave Background (CMB) physics can be used to constrain the
+dark energy dynamics: B modes of the polarization of the diffuse CMB emission
+as well as the polarized signal towards clusters of galaxies are sensitive to
+the Hubble expansion rate and thus the dark energy abundance in the early stage
+of cosmic acceleration. The first effect is sourced by gravitational lensing of
+large scale cosmic structures, the second is due to scattering of the primary
+CMB temperature anisotropy quadrupole by free electrons in cluster plasma. We
+are investigating the capabilities of ALMA to detect these effects and
+constrain the high-redshift dark energy abundance through measurements of
+sub-arcminute CMB anisotropies.",0703050v1
+1998-04-24,The Extraction of Anisotropic Contributions in Turbulent Flows,"We analyze turbulent velocity signals measured by two probes in the
+atmosphere, both at the height of 35 meters but displaced by 40 cm nominally
+orthogonal to the mean wind. Choosing a suitable coordinate system with respect
+to that of the mean wind, we derive theoretical forms for second order
+structure functions, and fit them to experimental data. We show that the effect
+of flow anisotropy is small on the longitudinal component but significant on
+the transverse component. The data provide an estimate of a universal exponent
+from among a hierarchy that governs the decay of flow anisotropy with the
+scale-size.",9804040v1
+1999-09-29,Universality and saturation of intermittency in passive scalar turbulence,"The statistical properties of a scalar field advected by the non-intermittent
+Navier-Stokes flow arising from a two-dimensional inverse energy cascade are
+investigated. The universality properties of the scalar field are directly
+probed by comparing the results obtained with two different types of injection
+mechanisms. Scaling properties are shown to be universal, even though
+anisotropies injected at large scales persist down to the smallest scales and
+local isotropy is not fully restored. Scalar statistics is strongly
+intermittent and scaling exponents saturate to a constant for sufficiently high
+orders. This is observed also for the advection by a velocity field rapidly
+changing in time, pointing to the genericity of the phenomenon. The persistence
+of anisotropies and the saturation are both statistical signatures of the
+ramp-and-cliff structures observed in the scalar field.",9909038v1
+1993-05-13,Anisotropic Electron Coupling as a Phenomenological Model for High-Temperature Superconductors,"A three-dimensional weak coupling BCS model with an {\it anisotropic} pairing
+interaction in momentum space is reported. It exhibits an anisotropic gap in
+accord with recent experimental observations for high-$T_c$ oxides. The gap
+ratio ${2 \Delta / k_B T_c }$ is calculated as function of the anisotropy ratio
+of the electron pairing. It is found that the mean gap ratio decreases with
+increasing anisotropy of the electron pairing, whereas the maximum gap ratio
+increases. Assuming a unique strength of the effective electron interaction the
+transition temperature turns out to be always larger than in the isotropic
+case. The temperature dependence of the gap in the Cu-O plane and along the
+c-axis of YBaCuO is presented.",9305009v1
+1994-04-18,Temperature dependence of the superconducting gap anisotropy in Bi$_{2}$Sr$_{2}$Ca$_{1}$Cu$_{2}$O$_{8+x}$,"We present the first detailed data of the momentum-resolved, temperature
+dependence of the superconducting gap of $Bi_{2}Sr_{2}Ca_{1}Cu_{2}O_{8+x}$,
+complemented by similar data on the intensity of the photoemission
+superconducting condensate spectral area. The gap anisotropy between the
+$\Gamma-\bar{M}$ and $\Gamma-X$ directions increases markedly with increasing
+temperature, contrary to what happens for conventional anisotropic-gap
+superconductors such as lead. Specifically, the size of the superconducting gap
+along the $\Gamma-X$ direction decreases to values indistinguishable from zero
+at temperatures for which the gap retains virtually full value along the
+$\Gamma-\bar{M}$ direction.",9404056v1
+1994-04-20,Gapless Phases in an s=1/2 Quantum Spin Chain with Bond Alternation,"The $S=1/2$ XXZ spin chain with the staggered XY anisotropy $$ H = J
+\sum_{n}^{N} (S^{x}_{n} S^{x}_{n+1} + S^{y}_{n} S^{y}_{n+1} + \Delta S^{z}_{n}
+S^{z}_{n+1}) - \delta \sum_{n}^{N} (-1)^{n} (S^{x}_{n} S^{x}_{n+1} - S^{y}_{n}
+S^{y}_{n+1}) $$ is shown to possess gapless, Luttinger-liquid-like phases in a
+wide range of its parameters: the XY-like phase and spin nematic phases, the
+latter characterized by a two-spin order parameter breaking translational and
+spin rotation symmetries. In the simplest, exactly solvable case $\Delta = 0$,
+the spectrum remains gapless at arbitrary $J$ and $\delta$ and is described by
+two massless Majorana (real) fermions with different velocities $v_{\pm} = |J
+\pm \delta|$. At $|\delta| < J$ the staggered XY anisotropy does not influence
+the ground state of the system (XY phase). At $|\delta| > J$, due to level
+crossing, a spin nematic state is realized, with $\uparrow \uparrow \downarrow
+\downarrow$ and $\uparrow \downarrow \downarrow \uparrow$ local symmetry of the
+$xx$ and $yy$ spin correlations. The spin correlation functions are calculated
+and the effect of thermally induced spin nematic ordering in the XY phase
+(""order from disorder"") is discussed. The role of a finite $\Delta$ is studied
+in the limiting cases $|\delta| \ll J$",9404063v1
+1994-12-02,Fluctuations and Instabilities of Ferromagnetic Domain Wall pairs in an External Magnetic Field,"Soliton excitations and their stability in anisotropic quasi-1D ferromagnets
+are analyzed analytically. In the presence of an external magnetic field, the
+lowest lying topological excitations are shown to be either soliton-soliton or
+soliton-antisoliton pairs. In ferromagnetic samples of macro- or mesoscopic
+size, these configurations correspond to twisted or untwisted pairs of Bloch
+walls. It is shown that the fluctuations around these configurations are
+governed by the same set of operators. The soliton-antisoliton pair has exactly
+one unstable mode and thus represents a critical nucleus for thermally
+activated magnetization reversal in effectively one-dimensional systems. The
+soliton-soliton pair is stable for small external fields but becomes unstable
+for large magnetic fields. From the detailed expression of this instability
+threshold and an analysis of nonlocal demagnetizing effects it is shown that
+the relative chirality of domain walls can be detected experimentally in thin
+ferromagnetic films. The static properties of the present model are equivalent
+to those of a nonlinear sigma-model with anisotropies. In the limit of large
+hard-axis anisotropy the model reduces to a double sine-Gordon model.",9412009v2
+1995-03-12,Exact Solutions of Anisotropic Diffusion-Limited Reactions with Coagulation and Annihilation,"We report exact results for one-dimensional reaction-diffusion models A+A ->
+inert, A+A -> A, and A+B -> inert, where in the latter case like particles
+coagulate on encounters and move as clusters. Our study emphasized anisotropy
+of hopping rates; no changes in universal properties were found, due to
+anisotropy, in all three reactions. The method of solution employed mapping
+onto a model of coagulating positive integer charges. The dynamical rules were
+synchronous, cellular-automaton type. All the asymptotic large-time results for
+particle densities were consistent, in the framework of universality, with
+other model results with different dynamical rules, when available in the
+literature.",9503064v1
+1995-05-19,MAGNETISATION REVERSAL AND DOMAIN STRUCTURE IN THIN MAGNETIC FILMS: THEORY AND COMPUTER SIMULATION,"A model is introduced for the theoretical description of nanoscale magnetic
+films with high perpendicular anisotropy. In the model the magnetic film is
+described in terms of single domain magnetic grains, interacting via exchange
+as well as via dipolar forces. Additionally, the model contains anisotropy
+energy and a coupling to an external magnetic field. Disorder is taken into
+account in order to describe realistic domain and domain wall structures.
+Within this framework the dependence of the energy on the film thickness can be
+discussed. The influence of a finite temperature as well as the dynamics can be
+modeled by a Monte Carlo simulation. The results on the hysteresis loops, the
+domain configurations, and the dynamics during the reversal process are in good
+agreement with experimental findings.",9505084v1
+1995-06-18,Magnetic anisotropies and general on--site Coulomb interactions in the cuprates,"This paper derives the anisotropic superexchange interactions from a Hubbard
+model for excitations within the copper 3d band and the oxygen 2p band of the
+undoped insulating cuprates. We extend the recent calculation of Yildirim et
+al. [Phys. Rev. B {\bf VV}, pp, 1995] in order to include the most general
+on--site Coulomb interactions (including those which involve more than two
+orbitals) when two holes occupy the same site. Our general results apply when
+the oxygen ions surrounding the copper ions form an octahedron which has
+tetragonal symmetry (but may be rotated as in lanthanum cuprate). For the
+tetragonal cuprates we obtain an easy--plane anisotropy in good agreement with
+experimental values. We predict the magnitude of the small in--plane aniso",9506076v1
+1995-11-20,Transverse Magnetoresistance of GaAs/AlGaAs Heterojunctions in the Presence of Parallel Magnetic Fields,"We have calculated the resistivity of a GaAs\slash AlGaAs heterojunction in
+the presence of both an in--plane magnetic field and a weak perpendicular
+component using a semiclassical Boltzmann transport theory. These calculations
+take into account fully the distortion of the Fermi contour which is induced by
+the parallel magnetic field. The scattering of electrons is assumed to be due
+to remote ionized impurities. A positive magnetoresistance is found as a
+function of the perpendicular component, in good qualitative agreement with
+experimental observations. The main source of this effect is the strong
+variation of the electronic scattering rate around the Fermi contour which is
+associated with the variation in the mean distance of the electronic states
+from the remote impurities. The magnitude of the positive magnetoresistance is
+strongly correlated with the residual acceptor impurity density in the GaAs
+layer. The carrier lifetime anisotropy also leads to an observable anisotropy
+in the resistivity with respect to the angle between the current and the
+direction of the in--plane magnetic field.",9511099v1
+1995-11-29,Anisotropic optical response of the diamond (111)-2x1 surface,"The optical properties of the 2$\times$1 reconstruction of the diamond (111)
+surface are investigated. The electronic structure and optical properties of
+the surface are studied using a microscopic tight-binding approach. We
+calculate the dielectric response describing the surface region and investigate
+the origin of the electronic transitions involving surface and bulk states. A
+large anisotropy in the surface dielectric response appears as a consequence of
+the asymmetric reconstruction on the surface plane, which gives rise to the
+zigzag Pandey chains. The results are presented in terms of the reflectance
+anisotropy and electron energy loss spectra. While our results are in good
+agreement with available experimental data, additional experiments are proposed
+in order to unambiguously determine the surface electronic structure of this
+interesting surface.",9511137v1
+1996-02-21,Impurity scattering in highly anisotropic superconductors and interband sign reversal of the order parameter,"We discuss various mechanisms that can lead to interband sign reversal of the
+order parameter in a multiband superconductor. In particular, we generalize
+Abrikosov-Gor'kov solution of the problem of weakly coupled superconductor with
+magnetic and nonmagnetic impurities on the case of arbitary order parameter
+anisotropy, including extreme cases as $d-$pairing or interband sign reversal
+of the order parameter, and show that interband scattering by magnetic
+impurities can stabilize an interband sign-reversal state. We discuss a
+possibility of such state in YBa$_2$Cu$_3$O$_7$ in the context of various
+experiments: Josephson tunneling, neutron scattering, isotope effect
+measurements.",9602118v1
+1996-08-27,Valence band spectroscopy in V-grooved quantum wires,"We present a combined theoretical and experimental study of the anisotropy in
+the optical absorption of V-shaped quantum wires. By means of realistic band
+structure calculations for these structures, we show that detailed information
+on the heavy- and light-hole states can be singled out from the anisotropy
+spectra {\em independently of the electron confinement}, thus allowing accurate
+valence band spectroscopy.",9608129v1
+1996-09-17,On the gap structure of UPt$_3$: phases A and B,"We have used thermal conduction and transverse sound attenuation to probe the
+anisotropy of the gap structure in two superconducting phases of UPt$_3$. For
+the low-temperature phase B, transverse sound has in the past provided strong
+evidence for a line node in the basal plane. Now, from the anisotropy of the
+thermal conductivity we further establish the presence of a node along the
+c-axis and provide information on its k-dependence. For the largely unexplored
+high-temperature phase A, our study of the attenuation for two directions of
+the polarization yields directional information on the quasiparticle spectrum,
+and the first clear indication of a different gap structure in the two phases.",9609161v1
+1996-09-28,Multifractal analysis of the metal-insulator transition in anisotropic systems,"We study the Anderson model of localization with anisotropic hopping in three
+dimensions for weakly coupled chains and weakly coupled planes. The eigenstates
+of the Hamiltonian, as computed by Lanczos diagonalization for systems of sizes
+up to $48^3$, show multifractal behavior at the metal-insulator transition even
+for strong anisotropy. The critical disorder strength $W_c$ determined from the
+system size dependence of the singularity spectra is in a reasonable agreement
+with a recent study using transfer matrix methods. But the respective spectrum
+at $W_c$ deviates from the ``characteristic spectrum'' determined for the
+isotropic system. This indicates a quantitative difference of the multifractal
+properties of states of the anisotropic as compared to the isotropic system.
+Further, we calculate the Kubo conductivity for given anisotropies by exact
+diagonalization. Already for small system sizes of only $12^3$ sites we observe
+a rapidly decreasing conductivity in the directions with reduced hopping if the
+coupling becomes weaker.",9609276v1
+1996-11-27,Micromagnetic Simulation of Nanoscale Films with Perpendicular Anisotropy,"A model is studied for the theoretical description of nanoscale magnetic
+films with high perpendicular anisotropy. In the model the magnetic film is
+described in terms of single domain magnetic grains with Ising-like behavior,
+interacting via exchange as well as via dipolar forces. Additionally, the model
+contains an energy barrier and a coupling to an external magnetic field.
+Disorder is taken into account in order to describe realistic domain and domain
+wall structures. The influence of a finite temperature as well as the dynamics
+can be modeled by a Monte Carlo simulation.
+  Many of the experimental findings can be investigated and at least partly
+understood by the model introduced above. For thin films the magnetisation
+reversal is driven by domain wall motion. The results for the field and
+temperature dependence of the domain wall velocity suggest that for thin films
+hysteresis can be described as a depinning transition of the domain walls
+rounded by thermal activation for finite temperatures.",9611218v1
+1996-12-18,Critical limit and anisotropy in the two-point correlation function of three-dimensional O(N) models,"In three-dimensional O(N) models, we investigate the low-momentum behavior of
+the two-point Green's function G(x) in the critical region of the symmetric
+phase. We consider physical systems whose criticality is characterized by a a
+rotationally-invariant fixed point.
+  In non rotationally-invariant physical systems with O(N)-invariant
+interactions, the vanishing of anisotropy in approaching the
+rotationally-invariant fixed point is described by a critical exponent rho,
+which is universal and is related to the leading irrelevant operator breaking
+rotational invariance. At N=infinity one finds rho=2. 1/N expansion and
+strong-coupling calculations show that, for all values of N>=0, rho~2.
+  Non-Gaussian corrections to the universal low-momentum behavior of G(x) are
+evaluated, and found to be very small.",9612164v1
+1996-12-31,Band structure and optical anisotropy in V-shaped and T-shaped semiconductor quantum wires,"We present a theoretical investigation of the electronic and optical
+properties of V- and T-shaped quantum wires. Valence band mixing as well as
+realistic sample geometries are fully included through an accurate and
+efficient approach that is described here in detail. We investigate the
+resulting valence band structure, which shows some significant peculiarities,
+such as an anomalously large spin splitting in the lowest heavy hole subband of
+T-shaped wires. For both classes of wires we obtain good agreement between
+calculated optical absorption and recent experimental spectra, and we
+demonstrate that the analysis of optical anisotropy can be used as an effective
+tool to extract information on valence states, usually very difficult to obtain
+otherwise.",9612251v1
+1997-04-23,Anisotropy of zero-bias diffusive anomalies for different orientations of an external magnetic field,"We consider the influence of the electron-electron interaction on the
+nonlinearity of the current-voltage characteristic of the tunnel junction at
+low bias (diffusive anomaly) in the presence of the classical magnetic field.
+We present the theory of a new phenomenon which manifests itself in the strong
+anisotropy of a diffusive anomaly for different orientations of the magnetic
+field with respect to the interface of the tunnel junction. The nonlinear
+differential tunneling conductance has a universal magnetic field dependence,
+so that only the magnetic field component perpendicular to the interface is
+involved. In particular, when the magnetic field is parallel to the interface,
+the I-V characteristic does not depend on the value of the magnetic field.",9704195v1
+1997-05-09,The two-point correlation function of three-dimensional O(N) models: critical limit and anisotropy,"In three-dimensional O(N) models, we investigate the low-momentum behavior of
+the two-point Green's function G(x) in the critical region of the symmetric
+phase. We consider physical systems whose criticality is characterized by a
+rotational-invariant fixed point. Several approaches are exploited, such as
+strong-coupling expansion of lattice non-linear O(N) sigma models,
+1/N-expansion, field-theoretical methods within the phi^4 continuum
+formulation. In non-rotational invariant physical systems with O(N)-invariant
+interactions, the vanishing of space-anisotropy approaching the
+rotational-invariant fixed point is described by a critical exponent rho, which
+is universal and is related to the leading irrelevant operator breaking
+rotational invariance. At N=\infty one finds rho=2. We show that, for all
+values of $N\geq 0$, $\rho\simeq 2$. Non-Gaussian corrections to the universal
+low-momentum behavior of G(x) are evaluated, and found to be very small.",9705086v1
+1997-06-15,Triangular Antiferromagnets,"In this article we review the effects of magnetic frustation in the stacked
+triangular lattice. Frustration increases the degeneracy of the ground state,
+giving rise to different physics. In particular it leads to unique phase
+diagrams with multicritical points and novel critical phenomena. We describe
+the confrontation of theory and experiment for a number of systems with
+differing magnetic Hamiltonians; Heisenberg, Heisenberg with easy-axis
+anisotropy, Heisenberg with easy-plane anisotropy, Ising and singlet ground
+state. Interestingly each leads to different magnetic properties and phase
+diagrams. We also describe the effects of ferromagnetic, rather than
+antiferromagnetic, stacking and of small distortions of the triangular lattice.",9706153v2
+1997-06-24,Ginzburg-Landau Expansion and the Slope of the Upper Critical Field in Superconductors with Anisotropic Normal Impurity Scattering,"Ginzburg-Landau expansion for superconductors with anisotropic $s-$ and
+$d-$wave pairing is derived in the presence of anisotropic normal impurity
+scattering which makes $d-$pairing state more stable under disordering. It is
+demonstrated that the slope of the upper critical field $|dH_{c2}/dT|_{T_{c}}$
+in superconductors with $d-$wave pairing has nonlinear dependence on disorder,
+i.e. for the low anisotropic scattering rate it drops rather fast with
+concentration of normal impurities, but as anisotropy of scattering increases
+it features initial nonlinear growth, approaches a maximum and drops again,
+vanishing at the critical impurity concentration. In superconductors with
+anisotropic $s-$wave pairing $|dH_{c2}/dT|_{T_{c}}$ grows, approaching the
+known asymptotic behavior, characteristic of usual isotropic case irrespective
+to the scattering anisotropy.",9706240v2
+1997-06-25,Domain Dynamics of Magnetic Films with Perpendicular Anisotropy,"We study the magnetic properties of nanoscale magnetic films with large
+perpendicular anisotropy comparing polarization microscopy measurements on
+Co_28Pt_72 alloy samples based on the magneto-optical Kerr effect with Monte
+Carlo simulations of a corresponding micromagnetic model. We focus on the
+understanding of the dynamics especially the temperature and field dependence
+of the magnetisation reversal process. The experimental and simulational
+results for hysteresis, the reversal mechanism, domain configurations during
+the reversal, and the time dependence of the magnetisation are in very good
+qualitative agreement. The results for the field and temperature dependence of
+the domain wall velocity suggest that for thin films the hysteresis can be
+described as a depinning transition of the domain walls rounded by thermal
+activation for finite temperatures.",9706253v1
+1997-09-01,Frequency shift and mode coupling in the nonlinear dynamics of a Bose condensed gas,"We investigate the behavior of large amplitude oscillations of a trapped
+Bose-condensed gas of alkali atoms at zero temperature, by solving the
+equations of hydrodynamics for collective modes. Due to the atom-atom
+interaction, the equations of motion are nonlinear and give rise to significant
+frequency shift and mode coupling. We provide analytic expressions for the
+frequency shift, pointing out the crucial role played by the anisotropy of the
+confining potential. For special values of the anisotropy parameter the mode
+coupling is particularly strong and the frequency shift becomes large,
+revealing a peculiar behavior of the Bose-condensed gas. Consequences on the
+theory of collapse and revival of collective excitations are also discussed.",9709010v1
+1997-11-18,Enhancement of Optical Nonlinearity Through Anisotropic Microstructures,"We investigate the polarization dependence of optical nonlinearity
+enhancement for a uniaxial anisotropic composite of metal nanocrystals in a
+dielectric host. Three cases are distinguished depending on whether the
+polarization is parallel, perpendicular or unpolarized with respect to the axis
+of anisotropy. For the parallel polarization, the results show that the 3D
+results are qualitatively similar to the 2D case reported recently. For the
+perpendicular polarization, the results are markedly different from the
+parallel counterpart: In contrast to the absorption, the enhancement factor
+actually increases with the anisotropy. Thus the separation of the absorption
+and enhancement peaks becomes even more pronounced than the parallel
+polarization case. These results indicate a strong polarization dependence of
+the nonlinear optical response.",9711166v1
+1997-12-19,On solitary waves in classical anisotropic Heisenberg chains with generalized boundary conditions,"We examine solitary waves in classical Heisenberg chains with an uniaxial
+anisotropy and a parallel magnetic field in a continuum approach. The boundary
+conditions commonly used are generalized to nonlinear spin wave states, which
+themselves turn out to be stable only for an anisotropy of the easy-plane type.
+In this case we obtain two different branches of one-soliton solutions which
+can be mapped onto each other by a formal time inversion. Moreover, they show
+some remarkable similarity to dark solitons of the Nonlinear Schr\""odinger
+equation. Numerical simulations for the discrete Heisenberg chain show that
+these solitary waves are highly, but not absolutely stable under interaction
+with linear excitations and as well under scattering with each other. The
+possible significance of these solitary waves in a phenomenological theory of
+one-dimensional magnets is briefly addressed.",9712241v1
+1998-01-09,Nonmonotonous Magnetic Field Dependence and Scaling of the Thermal Conductivity for Superconductors with Nodes of the Order Parameter,"We show that there is a new mechanism for nonmonotonous behavior of magnetic
+field dependence of the electronic thermal conductivity of clean
+superconductors with nodes of the order parameter on the Fermi surface. In
+particular, for unitary scatterers the nonmonotony of relaxation time takes
+place. Contribution from the intervortex space turns out to be essential for
+this effect even at low temperatures. Our results are in a qualitative
+agreement with recent experimental data for superconducting UPt_3. For
+E_{2u}-type of pairing we find approximately the scaling of the thermal
+conductivity in clean limit with a single parameter x=T/T_c\sqrt{B_{c2}/B} at
+low fields and low temperatures, as well as weak low-temperature dependence of
+the anisotropy ratio K_{zz}/K_{yy} in zero field. For E_{1g}-type of pairing
+deviations from the scaling are more noticeable and the anisotropy ratio is
+essentially temperature dependent.",9801076v1
+1998-03-11,Effects of Fermi Surface Anisotropy on Unconventional Superconductivity in UPt_3,"We discuss the weak-coupling BCS theory of the heavy fermion superconductor
+UPt_3, accounting for that system's anisotropic, multisheeted Fermi surface by
+expanding the order parameter and pair potential in terms of appropriate basis
+functions of the irreducible representations of the D_6h crystal point group.
+Within a phenomenological model for the electronic structure of UPt_3 chosen to
+capture the qualitative features of local density functional calculations and
+de Haas-van Alphen measurements, we show how Fermi surface anisotropy can favor
+pairing in certain symmetry classes, and influence the phase diagram of
+unconventional superconductors. We also calculate the Ginzburg-Landau
+coefficients, focussing on those coefficients relevant to current theories of
+the UPt_3 phase diagram.",9803135v1
+1998-04-06,The Phase Transition to a Square Vortex Lattice in Type-II Superconductors with Fourfold Anisotropy,"We investigate the stability of the square vortex lattice which has been
+recently observed in experiments on the borocarbide family of superconductors.
+Taking into account the tetragonal symmetry of these systems, we add fourfold
+symmetric fourth-derivative terms to the Ginzburg-Landau(GL) free energy. At
+$H_{c2}$ these terms may be treated perturbatively to lowest order to locate
+the transition from a distorted hexagonal to a square vortex lattice. We also
+solve for this phase boundary numerically in the strongly type-II limit,
+finding large corrections to the lowest-order perturbative results. We
+calculate the relative fourfold $H_{c2}$ anisotropy for field in the $xy$ plane
+to be 4.5% at the temperature, $T_c^{\Box}$, where the transition occurs at
+$H_{c2}$ for field along the $z$ axis. This is to be compared to the 3.6%
+obtained in the perturbative calculation. Furthermore, we find that the phase
+boundary in the $H-T$ phase diagram has positive slope near $H_{c2}$.",9804070v1
+1998-04-15,Flux-Line Lattice Structures in Untwinned YBa2Cu3O,"A small angle neutron scattering study of the flux-line lattice in a large
+single crystal of untwinned YBa2Cu3O is presented. In fields parallel to the
+c-axis, diffraction spots are observed corresponding to four orientations of a
+hexagonal lattice, distorted by the a-b anisotropy. A value for the anisotropy,
+the penetration depth ratio, of 1.18(2) was obtained. The high quality of the
+data is such that second order diffraction is observed, indicating a well
+ordered FLL. With the field at 33 degrees to c a field dependent re-orientation
+of the lattice is observed around 3T.",9804159v2
+1998-10-09,Magnetic anisotropy and low-energy spin waves in the Dzyaloshinskii-Moriya spiral magnet Ba_2 Cu Ge_2 O_7,"New neutron diffraction and inelastic scattering experiments are used to
+investigate in detail the field dependence of the magnetic structure and
+low-energy spin wave spectrum of the Dzyaloshinskii-Moriya helimagnet Ba_2 Cu
+Ge_2 O_7. The results suggest that the previously proposed model for the
+magnetism of this compound (an ideal sinusoidal spin spiral, stabilized by
+isotropic exchange and Dzyaloshinskii-Moriya interactions) needs to be refined.
+Both new and previously published data can be quantitatively explained by
+taking into account the Kaplan-Shekhtman-Entin-Wohlman-Aharony (KSEA) term, a
+special magnetic anisotropy term that was predicted to always accompany
+Dzyaloshinskii-Moriya interactions in insulators.",9810122v1
+1998-10-13,Anisotropic in-plane thermal conductivity of single-crystal YBa_2Cu_4O_8,"We report measurements of the in-plane thermal conductivity ($\kappa$) of
+YBa_2Cu_4O_8 (Y-124) single crystals in the temperature range $4K\leq T\leq
+300K$ and compare them with previous results on YBa_2Cu_3O_{6+x} (Y-123). For
+transport perpendicular to the CuO chains, $\kappa_a(300K)\simeq 10$W/mK, and
+along the chains, $\kappa_b(300K)\simeq 40$W/mK. The temperature dependence of
+$\kappa$ for both transport directions is much stronger than in
+YBa_2Cu_3O_{6+x} (Y-123), indicative of substantially superior lattice heat
+conduction in Y-124, and resulting in maximum values for $\kappa$ at $T\sim
+20$K exceeding 200W/mK. The data imply a surprisingly large anisotropy in the
+lattice conduction. $\kappa_a$ and $\kappa_b$ are enhanced in the
+superconducting state as in other cuprates. The magnitude and anisotropy of the
+enhancement are discussed and compared to those of Y-123.",9810152v1
+1998-11-07,Normal-state resistivity anisotropy in underdoped RBa_2Cu_3O_{6+x} crystals,"We have revealed new features in the out-of-plane resistivity rho_c of
+heavily underdoped RBa_2Cu_3O_{6+x} (R=Tm,Lu) single crystals, which give
+evidence for two distinct mechanisms contributing the c-axis transport. We have
+observed a crossover towards ""metal-like"" (d rho_c/d T > 0) behavior at the
+temperature T_m which quickly increases with decreasing doping. The
+""metal-like"" conductivity contribution dominates at T < T_m and provides a
+saturation of the resistivity anisotropy, rho_c / rho_{ab}. The
+antiferromagnetic ordering is found to block this ""metal-like"" part of the
+c-axis conductivity and complete decoupling of CuO_2 planes, which may be the
+reason of superconductivity disappearance.",9811104v1
+1998-12-02,Strongly Anisotropic Transport in Higher Two-Dimensional Landau Levels,"Low-temperature, electronic transport in Landau levels N>1 of a
+two-dimensional electron system is strongly anisotropic. At half-filling of
+either spin level of each such Landau level the magnetoresistance either
+collapses to form a deep minimum or is peaked in a sharp maximum, depending on
+the in-plane current direction. Such anisotropies are absent in the N=0 and N=1
+Landau level, which are dominated by the states of the fractional quantum Hall
+effect. The transport anisotropies may be indicative of a new many particle
+state, which forms exclusively in higher Landau levels.",9812025v1
+1998-12-03,Critical properties and phase diagram of the quantum anisotropic XY spin chain in a random magnetic field: A density-matrix renormalization-group analysis,"The spin-1/2 quantum anisotropic XY spin chain in a transverse random
+magnetic field parallel to the z axis is numerically studied by means of the
+density-matrix renormalization group. The dependence of the spontaneous
+magnetization and the energy gap on both the strength of the random magnetic
+field and the factor of anisotropy is determined. The critical line for the
+order-disorder phase transition is obtained and the resulting phase diagram is
+drawn. Our results are compatible with the fact that models with different
+factors of anisotropy fall within the same universality class as the quantum
+Ising model in a transverse random field.",9812056v2
+1998-12-16,Vortices with antiferromagnetic cores in the SO(5) theory of high temperature superconductivity,"We consider the problem of superconducting Ginzburg-Landau (G-L) vortices
+with antiferromagnetic cores which arise in Zhang's SO(5) model of
+antiferromagnetism (AF) and high temperature superconductivity (SC). This
+problem was previously considered by Arovas et al. who constructed approximate
+""variational"" solutions, in the large kappa limit, to estimate the domain of
+stability of such vortices in the temperature-chemical potential phase diagram.
+By solving the G-L equations numerically for general kappa, we show that the
+amplitude of the antiferromagnetic component at the vortex core decreases to
+zero continuously at a critical value of the AF-SC anisotropy (g~0.25) which is
+essentially independent of kappa for large kappa. The magnetic field profile,
+the vortex line energy and the value of the B-field at the center of the vortex
+core, as functions of anisotropy are also presented.",9812283v2
+1998-12-17,Spin wave analysis to the spatially-anisotropic Heisenberg antiferromagnet on triangular lattice,"We study the phase diagram at T=0 of the antiferromagnetic Heisenberg model
+on the triangular lattice with spatially-anisotropic interactions. For values
+of the anisotropy very close to J_alpha/J_beta=0.50, conventional spin wave
+theory predicts that quantum fluctuations melt the classical structures, for
+S=1/2. For the regime J_beta<J_alpha, it is shown that the incommensurate
+spiral phases survive until J_beta/J_alpha=0.27, leaving a wide region where
+the ground state is disordered. The existence of such nonmagnetic states
+suggests the possibility of spin liquid behavior for intermediate values of the
+anisotropy.",9812311v2
+1998-12-22,Self-Consistent Second Order Perturbation Theory for the Hubbard Model in Two Dimensions,"We apply self-consistent second order perturbation theory (SCSOPT) with
+respect to the on-site repulsive interaction U to study the Hubbard model in
+two dimensions. We investigate single particle properties of the model over the
+entire doping range at zero temperature. It is shown that as doping decreases
+toward half-filling $\omega$-mass enhancement factor increases, while k-mass
+enhancement factor decreases. The increase in $\omega$-mass enhancement factor
+is larger than the decrease in k-mass enhancement factor, so that total-mass is
+larger than that in the non-interacting case. When particle number density per
+unit cell n is given by 0.64<n<1.0 interaction enhances anisotropy of the Fermi
+surface, whereas at lower densities n<0.64 interaction suppresses anisotropy of
+it. Due to the decrease in k-mass enhancement factor the density of states
+(DOS) at the Fermi level is suppressed. It is possible to understand the
+results within the framework of the weak coupling Fermi liquid theory.",9812358v1
+1999-01-08,Anisotropy and magnetism of high temperature oxides superconductors,"Phonon or electron mediated weak BCS attraction is enough to have high
+critical temperature if a van Hove anomaly is at work. This could apply to
+electron doped compounds and also to compounds with CuO$_2$ planes overdoped in
+holes, where $T_c$ decreases with increasing doping. If phonons dominate, it
+should lead to an anisotropic but mainly $s$ superconductive gap, as observed
+recently in overdoped LaSrCuO, and probably also in electron doped compounds.
+If electrons dominate, a $d$ gap should develop as observed in a number of
+cases. In the underdoped range, the observed decrease of $T_c$ with hole doping
+can be related in all cases to the development of antiferromagnetic
+fluctuations which produces a magnetic pseudogap, thus lowering the density of
+states at the Fermi level. The observed mainly $d$ superconductive gap then can
+be due to a prevalent superconductive coupling through antiferromagnetic
+fluctuations; it could also possibly be attributed to the same phonon coupling
+as in the overdoped range, now acting on Bloch functions scattered in the
+magnetic pseudogap. More systematic studies of superconductive gap anisotropy
+and of magnetic fluctuations would be in order.",9901065v2
+1999-02-05,Phase transition between quantum and classical regimes for the escape rate of a biaxial spin system,"Employing the method of mapping the spin problem onto a particle one, we have
+derived the particle Hamiltonian for a biaxial spin system with a transverse or
+longitudinal magnetic field. Using the Hamiltonian and introducing the
+parameter $p (\equiv (U_{max}-E)/(U_{max}-U_{min}))$ where $U_{max}$ (U_{min})
+corresponds to the top (bottom) of the potential and $E$ is the energy of the
+particle, we have studied the first- or second-order transition around the
+crossover temperature between thermal and quantum regimes for the escape rate,
+depending on the anisotropy constant and the external magnetic field. It is
+shown that the phase boundary separating the first- and second-order transition
+and its crossover temperature are greatly influenced by the transverse
+anisotropy constant as well as the transverse or longitudinal magnetic field.",9902078v1
+1999-02-10,Low Temperature Static and Dynamic Behavior of the Two-Dimensional Easy-Axis Heisenberg Model,"We apply the self-consistent harmonic approximation (SCHA) to study static
+and dynamic properties of the two-dimensional classical Heisenberg model with
+easy-axis anisotropy. The static properties obtained are magnetization and spin
+wave energy as functions of temperature, and the critical temperature as a
+function of the easy-axis anisotropy. We also calculate the dynamic correlation
+functions using the SCHA renormalized spin wave energy. Our analytical results,
+for both static properties and dynamic correlation functions, are compared to
+numerical simulation data combining cluster-Monte Carlo algorithms and Spin
+Dynamics. The comparison allows us to conclude that far below the transition
+temperature, where the SCHA is valid, spin waves are responsible for all
+relevant features observed in the numerical simulation data; topological
+excitations do not seem to contribute appreciably. For temperatures closer to
+the transition temperature, there are differences between the dynamic
+correlation functions from SCHA theory and Spin Dynamics; these may be due to
+the presence of domain walls and solitons.",9902149v1
+1999-03-02,"Crystal Field, Magnetic Anisotropy and Excitations in Rare-Earth Hexaborides","We clarify the role of crystalline electric field (CEF) induced magnetic
+anisotropy in the ground state and spin-wave spectrum of cubic rare-earth
+materials with dominating isotropic magnetic exchange interactions. In
+particular we study the hexaboride NdB_6 which is shown to exhibit strong
+spin-quadrupolar coupling. The CEF scheme is analyzed and a non-collinear
+magnetization response is found. The spin orientation in the
+antiferromagnetically ordered ground-state is identified. Moreover, the spin
+excitations are evaluated and in agreement with inelastic neutron scattering a
+suppression of one of the two magnetic modes in the strong-coupling regime is
+predicted.",9903039v1
+1999-03-09,"Reply to Simon's Comment on ""Evidence for an Anisotropic State of Two-Dimensional Electrons in High Landau Levels""","We recently reported [PRL 82, 394 (1999)] large transport anisotropies in a
+two-dimensional electron gas in high Landau levels. These observations were
+made utilizing both square and Hall bar sample geometries. Simon recently
+commented [cond-mat/9903086] that a classical calculation of the current flow
+in the sample shows a magnification of an underlying anisotropy when using a
+square sample. In this reply we present more recent data obtained with a very
+high mobility sample, and reiterate that, with or without magnification, an
+anisotropic state develops in high Landau levels at very low temperatures.",9903153v1
+1999-05-04,"Quasiperiodicity, bistability and chaos in the Landau-Lifshitz equation","The dynamics of an individual magnetic moment is studied through the
+Landau-Lifshitz equation with a periodic driving in the direction perpendicular
+to the applied field. For fields lower than the anisotropy field and small
+values of the perturbation amplitude we have observed the magnetic moment
+bistability. At intermediate values we have found quasiperiodic bands
+alternating with periodic motion. At even larger values a chaotic regime is
+found. When the applied field is larger than the anisotropy one, the behavior
+is periodic with quasiperiodic regions. Those appear periodically in the
+amplitude of the oscillating field. Also, even for low values of the driving
+force, the moment is not parallel to the applied field.",9905034v1
+1999-06-04,Nematic phase of the two-dimensional electron gas in a magnetic field,"The two dimensional electron gas (2DEG) in moderate magnetic fields in
+ultra-clean AlAs-GaAs heterojunctions exhibits transport anomalies suggestive
+of a compressible, anisotropic metallic state. Using scaling arguments and
+Monte Carlo simulations, we develop an order parameter theory of an electron
+nematic phase. The observed temperature dependence of the resistivity
+anisotropy behaves like the orientational order parameter if the transition to
+the nematic state occurs at a finite temperature, $T_c \sim 65 mK$, and is
+slightly rounded by a small background microscopic anisotropy. We propose a
+light scattering experiment to measure the critical susceptibility.",9906064v2
+1999-06-17,High Magnetic Field ESR in the Haldane Spin Chains NENP and NINO,"We present electron spin resonance experiments in the one-dimensional
+antiferromagnetic S=1 spin chains NENP and NINO in pulsed magnetic fields up to
+50T. The measured field dependence of the quantum energy gap for B||b is
+analyzed using the exact diagonalization method and the density matrix
+renormalization group method (DMRG). A staggered anisotropy term (-1)^i d(S_i^x
+S_i^z + S_i^z S_i^x) was considered for the first time in addition to a
+staggered field term (-1)^i S_i^x B_st. We show that the spin dynamics in high
+magnetic fields strongly depends on the orthorhombic anisotropy E.",9906273v1
+1999-07-14,Mid-infrared Hall effect in thin-film metals: Probing the Fermi surface anisotropy in Au and Cu,"A sensitive mid-infrared (MIR, 900-1100 cm-1, 112-136 meV) photo-elastic
+polarization modulation technique is used to measure simultaneously Faraday
+rotation and circular dichroism in thin metal films. These two quantities
+determine the complex AC Hall conductivity. This novel technique is applied to
+study Au and Cu thin films at temperatures down to 20 K and magnetic fields up
+to 8 T. The Hall frequency is consistent with band theory predictions. We
+report the first measurement of the MIR Hall scattering rate, which is
+significantly lower than that derived from Drude analysis of zero magnetic
+field MIR transmission measurements. This difference is qualitatively explained
+in terms of the anisotropy of the Fermi surface in Au and Cu.",9907210v1
+1999-07-28,Tight-binding Hamiltonians for Sr filled ruthenates: application to the gap anisotropy and Hall coefficient in Sr2RuO4,"Accurate orthogonal tight-binding Hamiltonians are constructed for
+ferromagnetic SrRuO$_3$ and the layered perovskite superconductor,
+Sr$_2$RuO$_4$ by fitting to all-electron full-potential local density band
+structures obtained by the linearized augmented planewave method. These
+Hamiltonians allow the band structure to be computed on very fine meshes in the
+Brillouin zone at low cost, and additionally have analytic band velocities,
+while retaining the accuracy of the full-potential electronic structure
+calculations. This greatly facilitates calculation of transport and
+superconducting parameters related to the fermiology. These features are
+exploited to calculate the Hall coefficient and vortex lattice geometry for
+Sr$_2$RuO$_4$ with fine integration meshes. We find the lower limit for the
+interband order parameter anisotropy to be compatible with the observed square
+geometry. We also find that the sign reversal of the Hall coefficient can be
+explained in a conventional way if the bands are shifted by a few mRy so as to
+match the experimental de Haas-van Alphen areas exactly, {\it and} the
+temperature dependence of the relaxation time is strongly dependent on the band
+character.",9907442v1
+1999-08-02,Breakdown of the magnetization plateau of the S=1/2 ferromagnetic-ferromagnetic-antiferromagnetic trimerized spin chain with anisotropy,"We study the breakdown of the magnetization plateau at the magnetization
+M=M_{S}/3 (M_{S} is the saturation magnetization) of the S=1/2 anisotropic spin
+chain with ferromagnetic-ferromagnetic-antiferromagnetic interactions. We
+consider the model with the isotropic ferromagnetic (trimer) coupling J_{F},
+and anisotropic antiferromagnetic coupling (J_{x}=J_{y}=J_{AF} and J_{z}=\Delta
+J_{AF}). For the limit of large \gamma\equiv J_{F}/J_{AF}, the model is
+equivalent to the S=3/2 XXZ chain with the exchange anisotropy \Delta. There is
+a phase transition between the plateau (small-\gamma) and the no-plateau
+(large-\gamma) regions. This phase transition is of the
+Berezinskii-Kosterlitz-Thouless type, and we determine the phase boundary from
+the numerical diagonalization data. For \Delta=1, in particular, the phase
+transition between the plateau and the no-plateau regions occurs at the point
+\gamma_{c}=15.4.",9908027v2
+1999-08-09,Magnetic subband structure of an electron on a triangular lattice,"The effects of anisotropic nearest-neighbor (NN) and isotropic
+next-nearest-neighbor (NNN) hopping integrals on the magnetic subband structure
+of an electron on a triangular lattice are studied within the tight-binding
+approximation. A generalized Harper equation that includes both the NN and the
+NNN hopping terms is first derived. Then, the effects of anisotropic NN hopping
+integrals are examined and the results are compared in detail with those of an
+existing literature [Phys. Rev. B {\bf 56}, 3787 (1997)]. It is found that the
+hopping anisotropy generically leads to the occurrence of band broadening and
+gap closing. The effects of isotropic NNN hopping integrals are next examined,
+and it is found that introducing the NNN hopping integral changes considerably
+the magnetic subband structure; band broadening, gap closing, gap reopening,
+and band crossing occur depending on the strength of the isotropic NNN hopping
+integral. Symmetries of the magnetic subband structures with and without both
+the hopping anisotropy and the isotropic NNN hopping integrals are also
+discussed.",9908120v1
+1999-08-09,Critical Properties of Spin-1 Antiferromagnetic Heisenberg Chains with Bond Alternation and Uniaxial Single-Ion-Type Anisotropy,"One dimensional S=1 antiferromagnetic Heisenberg chains with bond alternation
+and uniaxial single-ion-type anisotropy are studied by numerical exact
+diagonalization of finite size systems. We calculate the ground state phase
+diagram using the twisted boundary condition method for $D\geq 0$. The ground
+states of this model contain the Haldane state, large-D state and the dimer
+state. Using conformal field theory and the level spectroscopy method, we
+calculate the D and $\delta$-dependence of the Luttinger liquid paraments K and
+the critical exponent $\nu$ of the energy gap.",9908125v2
+1999-08-09,"Magnetic anisotropy, first-order-like metamagnetic transitions and large negative magnetoresistance in the single crystal of Gd$_{2}$PdSi$_3$","Electrical resistivity ($\rho$), magnetoresistance (MR), magnetization,
+thermopower and Hall effect measurements on the single crystal
+Gd$_{2}$PdSi$_3$, crystallizing in an AlB$_2$-derived hexagonal structure are
+reported. The well-defined minimum in $\rho$ at a temperature above N\'eel
+temperature (T$_N$= 21 K) and large negative MR below $\sim$ 3T$_N$, reported
+earlier for the polycrystals, are reproducible even in single crystals. Such
+features are generally uncharacteristic of Gd alloys. In addition, we also
+found interesting features in other data, e.g., two-step first-order-like
+metamagnetic transitions for the magnetic field along [0001] direction. The
+alloy exhibits anisotropy in all these properties, though Gd is a S-state ion.",9908128v1
+1999-08-10,Pressure Dependence of the Irreversibility Line in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+δ}$:Role of Anisotropy in Flux-Line Formation,"One of the important problems of high-temperature superconductivity is to
+understand and ultimately to control fluxoid motion. We present the results of
+a new technique for measuring the pressure dependence of the transition to
+superconductivity in a diamond anvil cell. By measuring the third harmonic of
+the {\it ac} susceptibility, we determine the onset of irreversible flux
+motion. This enables us to study the effects of pressure on flux motion. The
+application of pressure changes interplanar spacing, and hence the interplanar
+coupling, without significantly disturbing the intraplanar superconductivity.
+Thus we are able to separate the effects of coupling from other properties that
+might affect the flux motion. Our results directly show the relationship
+between lattice spacing, effective- mass anisotropy, and the irreversibility
+line in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$. Our results also demonstrate
+that an application of 2.5 GPa pressure causes a dramatic increase in
+interplanar coupling.",9908156v2
+1999-08-12,Impurity-Induced Quasiparticle Transport and Universal Limit Wiedemann-Franz Violation in d-Wave Superconductors,"Due to the node structure of the gap in a d-wave superconductor, the presence
+of impurities generates a finite density of quasiparticle excitations at zero
+temperature. Since these impurity-induced quasiparticles are both generated and
+scattered by impurities, prior calculations indicate a universal limit (\Omega
+-> 0, T -> 0) where the transport coefficients obtain scattering-independent
+values, depending only on the velocity anisotropy v_f/v_2. We improve upon
+prior results, including the contributions of vertex corrections and Fermi
+liquid corrections in our calculations of universal limit electrical, thermal,
+and spin conductivity. We find that while vertex corrections modify electrical
+conductivity and Fermi liquid corrections renormalize both electrical and spin
+conductivity, only thermal conductivity maintains its universal value,
+independent of impurity scattering or Fermi liquid interactions. Hence, low
+temperature thermal conductivity measurements provide the most direct means of
+obtaining the velocity anisotropy for high T_c cuprate superconductors.",9908182v3
+1999-09-14,Energy-level statistics at the metal-insulator transition in anisotropic systems,"We study the three-dimensional Anderson model of localization with
+anisotropic hopping, i.e. weakly coupled chains and weakly coupled planes. In
+our extensive numerical study we identify and characterize the metal-insulator
+transition using energy-level statistics. The values of the critical disorder
+$W_c$ are consistent with results of previous studies, including the
+transfer-matrix method and multifractal analysis of the wave functions. $W_c$
+decreases from its isotropic value with a power law as a function of
+anisotropy. Using high accuracy data for large system sizes we estimate the
+critical exponent $\nu=1.45\pm0.2$. This is in agreement with its value in the
+isotropic case and in other models of the orthogonal universality class. The
+critical level statistics which is independent of the system size at the
+transition changes from its isotropic form towards the Poisson statistics with
+increasing anisotropy.",9909210v2
+1999-09-17,Shape Effects of Finite-Size Scaling Functions for Anisotropic Three-Dimensional Ising Models,"The finite-size scaling functions for anisotropic three-dimensional Ising
+models of size $L_1 \times L_1 \times aL_1$ ($a$: anisotropy parameter) are
+studied by Monte Carlo simulations. We study the $a$ dependence of finite-size
+scaling functions of the Binder parameter $g$ and the magnetization
+distribution function $p(m)$. We have shown that the finite-size scaling
+functions for $p(m)$ at the critical temperature change from a two-peak
+structure to a single-peak one by increasing or decreasing $a$ from 1. We also
+study the finite-size scaling near the critical temperature of the layered
+square-lattice Ising model, when the systems have a large two-dimensional
+anisotropy. We have found the three-dimensional and two-dimensional finite-size
+scaling behavior depending on the parameter which is fixed; a unified view of
+3D and 2D finite-size scaling behavior has been obtained for the anisotropic 3D
+Ising models.",9909262v1
+1999-10-21,Manifestations of the Charged Stripes in the Magnetoresistance of Heavily Underdoped YBa_2Cu_3O_{6+x},"We present a study of the in-plane and out-of-plane magnetoresistance (MR) in
+heavily-underdoped, antiferromagnetic YBa_2Cu_3O_{6+x}, which reveals a variety
+of striking features. The in-plane MR demonstrates a ""d-wave""-like anisotropy
+upon rotating the magnetic field H within the ab plane. With decreasing
+temperature below 20-25 K the system acquires memory: exposing a crystal to the
+magnetic field results in a persistent in-plane resistivity anisotropy. The
+overall features can be explained by assuming that the CuO_2 planes contain a
+developed array of stripes accommodating the doped holes, and that the MR is
+associated with the field-induced topological ordering of the stripes.",9910316v1
+1999-11-01,A New Vortex Solution for Two-Component Nonlinear Schroedinger Equation in Anisotropic Optical Media,"A theoretical study is given of a new type of optical vortex in nonlinear
+anisotropic media. This is realized as a special solution of the two-component
+non-linear Schroedinger equation. The vortex is inherent in the spin texture
+that is caused by an anisotropy of dielectric tensor, for which a role of spin
+is played by the Stokes vector (or pseudo-spin). By using the effective
+Lagrangian for the pseudo-spin field, we give an explicit form for the vortex
+solution for the case of two types of optical anisotropy; that is, nonlinear
+counterpart of birefringence giving rise to the Faraday and Cotton-Mouton
+effects. We also examine the evolution equation of the new vortex with respect
+to the propagation direction.",9910515v1
+1999-11-14,Gap anisotropy in the angle-resolved photoemission spectroscopy of Bi_2Sr_2CaCu_2O_{8+δ},"The gap anisotropy in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ is revisited in the
+framework of a d-wave scenario in view of the recent angle-resolved
+photoemission experiment. Based on a tight-binding fit to the normal state
+dispersion, a detail analysis on the effects of the inclusion of the next
+harmonic in the d-wave has been presented. Significant effect has been observed
+in the superconducting T$_c$. The density of states is linear at the nodes with
+enhanced weight, caused by a marked increase in the low energy excitaions which
+affect the thermodynamics considerably. The slope of the $\rho_s - T$ curve in
+the low temperature regime increases and the specific heat reflects the
+enhanced entropy at low temperatures. The leading edge of the ARPES energy
+distribution curves have been calculated and found to shift towards higher
+energy. The effect of scattering by non-magnetic impurities in this context is
+also outlined.",9911209v1
+1999-12-03,Torque magnetometry on single-crystal high temperature superconductors near the critical temperature: a scaling approach,"Angular-dependent magnetic torque measurements performed near the critical
+temperature on single crystals of HgBa_{2}CuO_{4+y}, La_{2-x}Sr{x}CuO_{4}, and
+YBa_{2}Cu_{3}O_{6.93} are scaled, following the 3D XY model, in order to
+determine the scaling function dG^{\pm}(z)/dz which describes the universal
+critical properties near T_{c}. A systematic shift of the scaling function with
+increasing effective mass anisotropy \gamma = (m_{ab}*/m_{c}*)^{1/2} is
+observed, which may be understood in terms of a 3D-2D crossover. Further
+evidence for a 3D-2D crossover is found from temperature-dependent torque
+measurements carried out in different magnetic fields at different field
+orientations \delta, which show a quasi 2D ""crossing region'' (M*,T*). The
+occurrence of this ""crossing phenomenon'' is explained in a phenomenological
+way from the weak z dependence of the scaling function around a value z = z*.
+The ""crossing'' temperature T* is found to be angular-dependent. Torque
+measurements above T_{c} reveal that fluctuations are strongly enhanced in the
+underdoped regime where the anisotropy is large, whereas they are less
+important in the overdoped regime.",9912052v1
+2000-01-04,Quantitative Description of Thermodynamics of Layered Magnets in a Wide Temperature Region,"The thermodynamics of layered antiferro- and ferromagnets with a weak
+interlayer coupling and/or easy-axis anisotropy is investigated. A crossover
+from an isotropic 2D-like to 3D Heisenberg (or 2D Ising) regime is discussed
+within the renormalization group (RG) analysis. Analytical results for the the
+(sublattice) magnetization and the ordering temperature are derived are
+obtained in different regimes. Numerical calculations on the base of the
+equations obtained yield a good agreement with experimental data on La2CuO4 and
+layered perovskites. Corresponding results for the Kosterlitz-Thouless and
+Curie (N\'eel) temperatures in the case of the easy-plane anisotropy are
+derived.",0001032v1
+2000-01-11,Theory of magnetic order in the three-dimensional spatially anisotropic Heisenberg model,"A spin-rotation-invariant Green's-function theory of long-range and
+short-range order (SRO) in the $S=1/2$ antiferromagnetic Heisenberg model with
+spatially anisotropic couplings on a simple cubic lattice is presented. The
+staggered magnetization, the two-spin correlation functions, the correlation
+leng spin-rotation-invariant Green's-function theory of long-range and
+short-range order (SRO) in the $S=1/2$ antiferromagnetic Heisenberg model with
+spatially anisotropic couplings on a simple cubic lattice is presented. The
+staggered magnetization, the two-spin correlation functions, the correlation
+lengths, and the static spin susceptibility are calculated self-consistently
+over the whole temperature region, where the effects of spatial anisotropy are
+explored. As compared with previous spin-wave approaches, the N\'{e}el
+temperature is reduced by the improved description of SRO. The maximum in the
+temperature dependence of the uniform static susceptibility is shifted with
+anisotropy and is ascribed to the decrease of SRO with increasing temperature.
+Comparing the theory with experimental data for the magnetization and
+correlation length of La$_2$CuO$_4$, a good agreement in the temperature
+dependences is obtained.",0001132v1
+2000-01-27,Hall effect and conduction anisotropy in the organic conductor TMTSF2PF6,"Long missing basic experiments in the normal phase of the anisotropic
+electron system of TMTSF2PF6 were performed. Both the Hall effect and the
+ab'-plane conduction anisotropy are directly addressing the unconventional
+electrical properties of this Bechgaard salt. We found that the dramatic
+reduction of the carrier density deduced from recent optical data is not
+reflected in an enhanced Hall-resistance. The pressure- and temperature
+dependence of the b'-direction resitivity reveal isotropic relaxation time and
+do not require explanations beyond the Fermi liquid theory. Our results allow a
+coherent-diffusive transition in the interchain carrier propagation, however
+the possible crossover to Luttinger liquid behavior is placed to an energy
+scale above room temperature.",0001403v1
+2000-01-27,Quasiparticle Spectrum of d-wave Superconductors in the Mixed State,"The quasiparticle spectrum of a two-dimensional d-wave superconductor in the
+mixed state, H_{c1} << H << H_{c2}, is studied both analytically and
+numerically using the linearized Bogoliubov-de Gennes equation. We consider
+various values of the ""anisotropy ratio"" v_F/v_Delta for the quasiparticle
+velocities at the Dirac points, and we examine the implications of symmetry.
+For a Bravais lattice of vortices, we find there is always an isolated
+energy-zero (Dirac point) at the center of the Brillouin zone, but for a
+non-Bravais lattice with two vortices per unit cell there is generally an
+energy gap. In both of these cases, the density of states should vanish at zero
+energy, in contrast with the semiclassical prediction of a constant density of
+states, though the latter may hold down to very low energies for large
+anisotropy ratios. This result is closely related to the particle-hole symmetry
+of the band structures in lattices with two vortices per unit cell. More
+complicated non-Bravais vortex lattice configurations with at least four
+vortices per unit cell can break the particle-hole symmetry of the linearized
+energy spectrum and lead to a finite density of states at zero energy.",0001406v1
+2000-02-04,Generalization properties of finite size polynomial Support Vector Machines,"The learning properties of finite size polynomial Support Vector Machines are
+analyzed in the case of realizable classification tasks. The normalization of
+the high order features acts as a squeezing factor, introducing a strong
+anisotropy in the patterns distribution in feature space. As a function of the
+training set size, the corresponding generalization error presents a crossover,
+more or less abrupt depending on the distribution's anisotropy and on the task
+to be learned, between a fast-decreasing and a slowly decreasing regime. This
+behaviour corresponds to the stepwise decrease found by Dietrich et al.[Phys.
+Rev. Lett. 82 (1999) 2975-2978] in the thermodynamic limit. The theoretical
+results are in excellent agreement with the numerical simulations.",0002071v1
+2000-02-08,Spin quantization axis dependent magnetic properties and x-ray magnetic circular dichroism of FePt and CoPt,"We have performed a theoretical study of the magnetic circular dichroism in
+the x-ray absorption spectra (XMCD) of the equiatomic CoPt and FePt ordered
+alloys as a function of the spin quantization axis. We found that the
+magnetization axis is along the [001] direction and the magneto-crystalline
+anisotropy energy (MCA) for the FePt compound is twice as large as that of the
+CoPt compound in agreement with experiment. The band structure and the total
+density of states confirm that all electronic states contribute to the MCA, and
+not just the states at the vicinity of the Fermi level. The orbital magnetic
+moments decrease with respect to the angle between the [001] axis and the spin
+quantization axis, and are much larger for the CoPt compound. We show that the
+orbital moment anisotropy is reflected in the XMCD signal.",0002110v1
+2000-02-29,Impurity spin magnetization of thin Fe doped Au films,"In order to probe the influence of the surface-induced anisotropy on the
+impurity spin magnetization, we measure the anomalous Hall effect in thin AuFe
+films at magnetic fields up to 15 T. The observed suppression of the anomalous
+Hall resistivity at low fields as well as the appearance of a minimum in the
+differential Hall resistivity at higher fields can be explained by our
+theoretical model which takes into account the influence of a polycrystalline
+film structure on the surface-induced anisotropy. Our results imply that the
+apparent discrepancy between different experimental results for the size
+effects in dilute magnetic alloys can be linked to a different microstructure
+of the samples.",0002467v1
+2000-03-27,Quantum chiral phases in frustrated easy-plane spin chains,"The phase diagram of antiferromagnetic spin-S chain with XY-type anisotropy
+and frustrating next-nearest-neighbor interaction is studied in the limit of
+large integer S with the help of a field-theoretical approach. It is shown that
+the existence of gapless and gapped chiral phases found in recent numerical
+studies [M.Kaburagi et al., J. Phys. Soc. Jpn. vol.68, 3185 (1999), T.Hikihara
+et al., J. Phys. Soc. Jpn. vol.69, 259 (2000)] is not specific for S=1, but is
+rather a generic large-S feature. Estimates for the corresponding transition
+boundaries are obtained, and a sketch of the typical phase diagram is
+presented. It is also shown that frustration stabilizes the Haldane phase
+against the variation of the anisotropy.",0003427v1
+2000-03-27,Pseudospin Anisotropy Classification of Quantum Hall Ferromagnets,"Broken symmetry ground states with uniform electron density are common in
+quantum Hall systems when two Landau levels simultaneously approach the
+chemical potential at integer filling factor $\nu$. The close analogy between
+these two-dimensional electron system states and conventional itinerant
+electron ferromagnets can be emphasized by using a pseudospin label to
+distinguish the two Landau levels. As in conventional ferromagnets, the
+evolution of the system's state as external field parameters are varied is
+expected to be sensitive to the dependence of ground state energy on pseudospin
+orientation. We discuss the predictions of Hartree-Fock theory for the
+dependence of the sign and magnitude of the pseudospin anisotropy energy on the
+nature of the crossing Landau levels. We build up a classification scheme for
+quantum Hall ferromagnets that applies for single layer and bilayer systems
+with two aligned Landau levels distinguished by any combination of real-spin,
+orbit-radius, or growth direction degree-of-freedom quantum numbers. The
+possibility of in-situ tuning between easy-axis and easy-plane quantum Hall
+ferromagnets is discussed for biased bilayer systems with total filling factors
+$\nu=3$ or $\nu=4$. Detailed predictions are made for the bias dependence of
+pseudospin reversal properties in $\nu=3$ bilayer systems.",0003430v1
+2000-03-30,Reorientation of Anisotropy in a Square Well Quantum Hall Sample,"We have measured magnetotransport at half-filled high Landau levels in a
+quantum well with two occupied electric subbands. We find resistivities that
+are {\em isotropic} in perpendicular magnetic field but become strongly {\em
+anisotropic} at $\nu$ = 9/2 and 11/2 on tilting the field. The anisotropy
+appears at an in-plane field, $B_{ip} \sim$ 2.5T, with the easy-current
+direction {\em parallel} to $B_{ip}$ but rotates by 90$^{\circ}$ at $B_{ip}
+\sim$ 10T and points now in the same direction as in single-subband samples.
+This complex behavior is in quantitative agreement with theoretical
+calculations based on a unidirectional charge density wave state model.",0003483v1
+2000-04-03,The effect of rare regions on a disordered itinerant quantum antiferromagnet with cubic anisotropy,"We study the quantum phase transition of an itinerant antiferromagnet with
+cubic anisotropy in the presence of quenched disorder, paying particular
+attention to the locally ordered spatial regions that form in the Griffiths
+region. We derive an effective action where these rare regions are described in
+terms of static annealed disorder. A one loop renormalization group analysis of
+the effective action shows that for order parameter dimensions $p<4$ the rare
+regions destroy the conventional critical behavior. For order parameter
+dimensions $p>4$ the critical behavior is not influenced by the rare regions,
+it is described by the conventional dirty cubic fixed point. We also discuss
+the influence of the rare regions on the fluctuation-driven first-order
+transition in this system.",0004013v1
+2000-04-10,Magnetotransport study of the charged stripes in high-T_c cuprates,"We present a study of the in-plane and out-of-plane magnetoresistance (MR) in
+heavily-underdoped, antiferromagnetic YBa_{2}Cu_{3}O_{6+x}, which reveals a
+variety of striking features. The in-plane MR demonstrates a ""d-wave""-like
+anisotropy upon rotating the magnetic field H within the ab plane. With
+decreasing temperature below 20-25 K, the system acquires memory: exposing a
+crystal to the magnetic field results in a persistent in-plane resistivity
+anisotropy. The overall features can be explained by assuming that the CuO_2
+planes contain a developed array of stripes accommodating the doped holes, and
+that the MR is associated with the field-induced topological ordering of the
+stripes.",0004135v1
+2000-04-10,Combined Paramagnetic and Diamagnetic Response of YBCO,"It has been predicted that the zero frequency density of states of YBCO in
+the superconducting phase can display interesting anisotropy effects when a
+magnetic field is applied parallel to the copper-oxide planes, due to the
+diamagnetic response of the quasi-particles. In this paper we incorporate
+paramagnetism into the theory and show that it lessens the anisotropy and can
+even eliminate it altogether. At the same time paramagnetism also changes the
+scaling with the square root of the magnetic field first deduced by Volovik
+leading to an experimentally testable prediction. We also map out the analytic
+structure of the zero frequency density of states as a function of the
+diamagnetic and paramagnetic energies. At certain critical magnetic field
+values we predict kinks as we vary the magnetic field. However these probably
+lie beyond currently accessible field strengths.",0004152v1
+2000-05-12,Reflectivity Anisotropy Spectra of Cu- and Ag- (110) surfaces from {\it ab initio} theory,"We are able to disentagle the effects of the intraband and interband parts of
+the bulk dielectric function on the bare dielectric anisotropy of the surface.
+We show how the position, sign and amplitude of the structures observed in such
+spectra depend on the above quantities. The lineshape of all the calculated
+structures agree very well with the ones observed experimentally for samples
+treated by suitable surface cleaning. In particular, we reproduce the observed
+single peak structure of Ag at high energy, found to represent a state of the
+clean surface different from the one giving the originally observed double peak
+structure. This results is not reproduced by the 'local field' model.",0005209v1
+2000-06-06,Influence of nonlocal electrodynamics on the anisotropic vortex pinning in $YNi_2B_2C$,"We have studied the pinning force density Fp of YNi_2B_2C superconductors for
+various field orientations. We observe anisotropies both between the c-axis and
+the basal plane and within the plane, that cannot be explained by usual mass
+anisotropy. For magnetic field $H \parallel c$, the reorientation structural
+transition in the vortex lattice due to nonlocality, which occurs at a field
+$H_1 \sim 1kOe$, manifests itself as a kink in Fp(H). When $H \bot c$, Fp is
+much larger and has a quite different H dependence, indicating that other
+pinning mechanisms are present. In this case the signature of nonlocal effects
+is the presence of a fourfold periodicity of Fp within the basal plane.",0006077v2
+2000-06-08,Periodic forcing in viscous fingering of a nematic liquid crystal,"We study viscous fingering of an air-nematic interface in a radial Hele-Shaw
+cell when periodically switching on and off an electric field, which reorients
+the nematic and thus changes its viscosity, as well as the surface tension and
+its anisotropy (mainly enforced by a single groove in the cell). We observe
+undulations at the sides of the fingers which correlate with the switching
+frequency and with tip oscillations which give maximal velocity to smallest
+curvatures. These lateral undulations appear to be decoupled from spontaneous
+(noise-induced) side branching. We conclude that the lateral undulations are
+generated by successive relaxations between two limiting finger widths. The
+change between these two selected pattern scales is mainly due to the change in
+the anisotropy. This scenario is confirmed by numerical simulations in the
+channel geometry, using a phase-field model for anisotropic viscous fingering.",0006131v3
+2000-06-28,Chiral ordered phases in a frustrated S=1 chain with uniaxial single-ion-type anisotropy,"The ground-state phase transitions of a frustrated S=1 Heisenberg chain with
+the uniaxial single-ion-type anisotropy and the frustrating
+next-nearest-neighbor coupling are studied. For the system, it has been shown
+that there are gapless and gapped chiral phases in which the chirality \kappa_l
+= S^x_l S^y_{l+1} - S^y_l S^x_{l+1} exhibits a finite long-range order (LRO)
+and the spin correlation decays either algebraically or exponentially. In this
+study, the transitions between the Haldane and chiral phase and between the
+large-D (LD) and chiral phase are investigated using the infinite-system
+density-matrix renormalization group method. It is found that there exist two
+types of gapped chiral phases, ""chiral Haldane"" and ""chiral LD"" phases, in
+which the string LRO coexists with the chiral LRO and the string correlation
+decays exponentially, respectively.",0006445v1
+2000-07-18,Measuring anisotropic scattering in the cuprates,"A simple model of anisotropic scattering in a quasi two-dimensional metal is
+studied. Its simplicity allows an analytic calculation of transport properties
+using the Boltzmann equation and relaxation time approximation. We argue that
+the c-axis magnetoresistance provides the key test of this model of transport.
+We compare this model with experiments on overdoped Tl-2201 and find reasonable
+agreement using only weak scattering anisotropy. We argue that optimally doped
+Tl-2201 should show strong angular-dependent magnetoresistance within this
+model and would provide a robust way of determining the in-plane scattering
+anisotropy in the cuprates.",0007299v2
+2000-08-02,"Confinement symmetry, mobility anisotropy, and metallic behavior in (311)A GaAs 2D holes","We study two dimensional hole systems confined to GaAs quantum wells grown on
+the (311)A surface of GaAs substrates. Such samples exhibit an in-plane
+mobility anisotropy. At constant 2D hole density, we vary the symmetry of the
+quantum well potential and measure the temperature dependence of the
+resistivity along two different current directions, in a regime where the
+samples exhibit metallic behavior. The symmetry has a significant and
+non-trivial effect on the metallic behavior. Moreover, differences between the
+temperature-dependence of the resistivity along the two mobility directions
+point to specific scattering mechanisms being important in the expression of
+the metallic behavior.",0008041v1
+2000-08-28,Josephson-Vortex-Glass Transition in Strong Fields,"A vortex-glass transition due to point disorder in layered superconductors is
+studied for the case with an applied field {\it parallel} to the layers. Our
+calculation of tilt responses indicates that, irrespective of the magnitude of
+the field, the resulting glass phase, Josephson-vortex-glass (JG), should have
+a transverse Meissner effect, as in a planar splayed glass phase, only for a
+tilt perpendicular to the layers. Further, focusing on the high field (and/or
+high anisotropy) region $B \sqrt{\Gamma} > \phi_0/d^2$, where $\Gamma$ is the
+mass anisotropy in the Lawrence-Doniach model, the JG transition line
+$T_{JG}(B)$ is shown to have a similar form to a $B$-$T$ line following from
+the {\it disorder-free} Lindemann criterion and to decrease with increasing $B
+\sqrt{\Gamma}$, in marked contrast to the disorder-free melting line {\it
+insensitive to} $B \sqrt{\Gamma}$ in such the high field region. This
+$T_{JG}(B)$ line seems to have been recently observed in a.c. susceptibility
+and in-plane resistivity measurements in BSCCO and qualitatively explains a
+field dependence at lower temperatures of previous BSCCO resistivity data
+showing the so-called in-plane Lorentz force-free behavior.",0008397v1
+2000-09-01,The Broad Brillouin Doublet and CP of Ktao_3 : Second Sound vs. Two-Phonon Difference Scattering,"Low-T Brillouin spectra of the incipient ferroelectric KTaO3 exhibit a broad
+central peak (CP), and additional Brillouin doublets (BD), that can both be
+related to phonon-density fluctuations. On the basis of new high-resolution
+neutron data obtained of low-lying phonon branches, we analysed the
+phonon-kinetics mechanisms that are possibly the origin of these unusual
+features. Firstly, transverse acoustic (TA) phonons whose normal damping is
+faster than the BD frequency can produce hydrodynamic second sound. Secondly,
+two-phonon difference scattering from low damping thermal transverse phonons
+contribute to the spectra with either a sharp or a broader doublet, depending
+on the phonon group velocity and anisotropy of dispersion surfaces. The
+position of the observed sharp doublet is consistent with both mechanisms, but
+a comparison of the computed and experimental anisotropies favours the second
+process.",0009011v1
+2000-09-28,Magnetic qubits as hardware for quantum computers,"We propose two potential realisations for quantum bits based on nanometre
+scale magnetic particles of large spin S and high anisotropy molecular
+clusters. In case (1) the bit-value basis states |0> and |1> are the ground and
+first excited spin states Sz = S and S-1, separated by an energy gap given by
+the ferromagnetic resonance (FMR) frequency. In case (2), when there is
+significant tunnelling through the anisotropy barrier, the qubit states
+correspond to the symmetric, |0>, and antisymmetric, |1>, combinations of the
+two-fold degenerate ground state Sz = +- S. In each case the temperature of
+operation must be low compared to the energy gap, \Delta, between the states
+|0> and |1>. The gap \Delta in case (2) can be controlled with an external
+magnetic field perpendicular to the easy axis of the molecular cluster. The
+states of different molecular clusters and magnetic particles may be entangled
+by connecting them by superconducting lines with Josephson switches, leading to
+the potential for quantum computing hardware.",0009432v1
+2001-01-20,Ultrasound Attenuation in Sr$_2$RuO$_4$: an Angle-Resolved Study of the Superconducting Gap Function,"We present a study of the electronic ultrasound attenuation $\alpha$ in the
+unconventional superconductor Sr$_2$RuO$_4$ . The power law behavior of
+$\alpha$ at temperatures down to $T_c/30$ clearly indicates the presence of
+nodes in the gap. In the normal state, we find an enormous anisotropy of
+$\alpha$ in the basal plane of the tetragonal structure. In the superconducting
+state, the temperature dependence of $\alpha$ also exhibits significant
+anisotropy. We discuss these results in relation to possible gap functions.",0101319v2
+2001-01-26,Highly Anisotropic Transport in the Integer Quantum Hall Effect,"At very large tilt of the magnetic (B) field with respect to the plane of a
+two-dimensional electron system the transport in the integer quantum Hall
+regime at $\nu$ = 4, 6, and 8 becomes strongly anisotropic. At these filling
+factors the usual {\em deep minima} in the magneto-resistance occur for the
+current flowing {\em perpendicular} to the in-plane B field direction but
+develop into {\em strong maxima} for the current flowing {\em parallel} to the
+in-plane B field. The origin of this anisotropy is unknown but resembles the
+recently observed anisotropy at half-filled Landau levels.",0101416v1
+2001-01-29,Phase transitions in two-dimensional anisotropic quantum magnets,"We consider quantum Heisenberg ferro- and antiferromagnets on the square
+lattice with exchange anisotropy of easy-plane or easy-axis type. The
+thermodynamics and the critical behaviour of the models are studied by the
+pure-quantum self-consistent harmonic approximation, in order to evaluate the
+spin and anisotropy dependence of the critical temperatures. Results for
+thermodynamic quantities are reported and comparison with experimental and
+numerical simulation data is made. The obtained results allow us to draw a
+general picture of the subject and, in particular, to estimate the value of the
+critical temperature for any model belonging to the considered class.",0101430v1
+2001-02-21,Renormalization group and nonlinear susceptibilities of cubic ferromagnets at criticality,"For the three-dimensional cubic model, the nonlinear susceptibilities of the
+fourth, sixth, and eighth orders are analyzed and the parameters \delta^(i)
+characterizing their reduced anisotropy are evaluated at the cubic fixed point.
+In the course of this study, the renormalized sextic coupling constants
+entering the small-field equation of state are calculated in the four-loop
+approximation and the universal values of these couplings are estimated by
+means of the Pade-Borel-Leroy resummation of the series obtained. The
+anisotropy parameters are found to be: \delta^(4) = 0.054 +/- 0.012, \delta^(6)
+= 0.102 +/- 0.02, and \delta^(8) = 0.144 +/- 0.04, indicating that the
+anisotropic (cubic) critical behavior predicted by the advanced higher-order
+renormalization-group analysis should be, in principle, visible in physical and
+computer experiments.",0102368v3
+2001-03-01,The Hamiltonian of the V$_{15}$ Spin System from first-principles Density-Functional Calculations,"We report first-principles all-electron density-functional based studies of
+the electronic structure, magnetic ordering and anisotropy for the V$_{15}$
+molecular magnet. From these calculations, we determine a Heisenberg
+Hamiltonian with four antiferromagnetic and one {\em ferromagnetic} coupling.
+We perform direct diagonalization to determine the temperature dependence of
+the susceptibility. This Hamiltonian reproduces the experimentally observed
+spin $S$=1/2 ground state and low-lying $S$=3/2 excited state. A small
+anisotropy term is necessary to account for the temperature independent part of
+the magnetization curve.",0103031v2
+2001-03-02,Competition Between Exchange and Anisotropy in a Pyrochlore Ferromagnet,"The Ising-like spin ice model, with a macroscopically degenerate ground
+state, has been shown to be approximated by several real materials. Here we
+investigate a model related to spin ice, in which the Ising spins are replaced
+by classical Heisenberg spins. These populate a cubic pyrochlore lattice and
+are coupled to nearest neighbours by a ferromagnetic exchange term J and to the
+local <1,1,1> axes by a single-ion anisotropy term D. The near neighbour spin
+ice model corresponds to the case D/J infinite. For finite D/J we find that the
+macroscopic degeneracy of spin ice is broken and the ground state is
+magnetically ordered into a four-sublattice structure. The transition to this
+state is first-order for D/J > 5 and second-order for D/J < 5 with the two
+regions separated by a tricritical point. We investigate the magnetic phase
+diagram with an applied field along [1,0,0] and show that it can be considered
+analogous to that of a ferroelectric.",0103051v1
+2001-03-15,Phase Transition Of The Spin-One Square-Lattice Anisotropic Heisenberg Model,"The coupled cluster method (CCM) is applied to the spin-one anisotropic
+Heisenberg antiferromagnet (HAF) on the square lattice at zero temperature
+using a new high-order CCM ground-state formalism for general quantum spin
+number ($s \ge 1/2$). The results presented constitute the first such
+application of this new formalism, and they are shown to be among the most
+accurate results for the ground-state energy and sublattice magnetisation of
+this model as yet determined. We ``track'' the solution to the CCM equations at
+a given level of approximation with respect to the anisotropy parameter,
+$\Delta$, from the trivial Ising limit ($\Delta \to \infty$) down to a critical
+value $\Delta_c$, at which point this solution terminates. This behaviour is
+associated with a phase transition in the system, and hence a primary result of
+these high-order CCM calculations is that they provide an accurate and unbiased
+(i.e., {\it ab initio}) estimation of the position of the quantum phase
+transition point as a function of the anisotropy parameter. Our result is,
+namely, that this point occurs at (or slightly below) the isotropic Heisenberg
+point at $\Delta=1$, for this model.",0103321v1
+2001-03-16,Quantum Hall Stripe States in a Tilted Magnetic Field,"A strong anisotropy in the longitudinal resistivity of a 2D electron system
+has been observed at half-filled high Landau levels. We report on detailed
+Hartree-Fock calculations of the unidirectional charge density wave (UCDW)
+orientation energy induced by a tilted magnetic field. We find that stripes can
+orient both parallel or perpendicular to the in-plane field depending on the
+sample parameters and field strength. The close agreement between complex
+experimental data on different sample geometries and our theoretical results
+strongly support the UCDW picture as the origin of the observed anisotropies in
+high Landau levels.",0103339v1
+2001-03-20,Fully dense MgB_2 superconductor textured by hot deformation,"Bulk textured MgB_2 material of nearly full density showing a weak c-axis
+alignment of the hexagonal MgB_2 grains parallel to the pressure direction was
+obtained by hot deformation of a stoichiometric MgB_2 pellet prepared by a
+gas-solid reaction. The texture of the material was verified by comparing the
+x-ray diffraction patterns of the hot deformed material with isotropic MgB_2
+powder. A small, but distinct anisotropy of the upper critical field up to
+Hc2^{a,b}/Hc2^{c}~1.2 depending on degree of texture was found by resistance
+and susceptibility measurements. No anisotropy of the critical current density
+determined from magnetization measurements was found for the textured material.",0103408v2
+2001-04-05,Decoupling of the S=1/2 antiferromagnetic zig-zag ladder with anisotropy,"The spin-1/2 antiferromagnetic zig-zag ladder is studied by exact
+diagonalization of small systems in the regime of weak inter-chain coupling. A
+gapless phase with quasi long-range spiral correlations has been predicted to
+occur in this regime if easy-plane (XY) anisotropy is present. We find in
+general that the finite zig-zag ladder shows three phases: a gapless collinear
+phase, a dimer phase and a spiral phase. We study the level crossings of the
+spectrum,the dimer correlation function, the structure factor and the spin
+stiffness within these phases, as well as at the transition points. As the
+inter-chain coupling decreases we observe a transition in the anisotropic XY
+case from a phase with a gap to a gapless phase that is best described by two
+decoupled antiferromagnetic chains. The isotropic and the anisotropic XY cases
+are found to be qualitatively the same, however, in the regime of weak
+inter-chain coupling for the small systems studied here. We attribute this to a
+finite-size effect in the isotropic zig-zag case that results from
+exponentially diverging antiferromagnetic correlations in the weak-coupling
+limit.",0104090v1
+2001-04-10,Anomalous Superconducting Properties and Field Induced Magnetism in CeCoIn5,"In the heavy fermion superconductor CeCoIn5 (Tc=2.3K) the critical field is
+large, anisotropic and displays hysteresis. The magnitude of the critical-field
+anisotropy in the a-c plane can be as large as 70 kOe and depends on
+orientation. Critical field measurements in the (110) plane suggest 2D
+superconductivity, whereas conventional effective mass anisotropy is observed
+in the (100) plane. Two distinct field-induced magnetic phases are observed: Ha
+appears deep in the superconducting phase, while Hb intersects Hc2 at T=1.4 K
+and extends well above Tc. These observations suggest the possible realization
+of a direct transition from ferromagnetism to Fulde-Ferrel-Larkin-Ovchinnikov
+superconductivity in CeCoIn5.",0104179v2
+2001-04-20,Millikelvin magnetic relaxation measurements of alpha-Fe2O3 antiferromagnetic particles,"In this paper we report magnetic relaxation data for antiferromagnetic
+alpha-Fe2O3 particles of 5 nm mean diameter in the temperature range 0.1 K to
+25 K. The average spin value of these particles S=124 and the uniaxial
+anisotropy constant D=1.6x10^-2 K have been estimated from the experimental
+values of the blocking temperature and anisotropy field. The observed plateau
+in the magnetic viscosity from 3 K down to 100 mK agrees with the occurrence of
+spin tunneling from the ground state Sz = S. However, the scaling M vs Tln(nu
+t) is broken below 5 K, suggesting the occurrence of tunneling from excited
+states below this temperature.",0104391v1
+2001-04-24,Magnetothemopower study of quasi two-dimensional organic conductor $α$-(BEDT-TTF)$_2$KHg(SCN)$_4$,"We have used a low-frequency magneto-thermopower (MTEP) method to probe the
+high magnetic field ground state behavior of
+$\alpha$-(BEDT-TTF)$_2$KHg(SCN)$_4$ along all three principal crystallographic
+axes at low temperatures. The thermopower tensor coefficients ($S_{xx}, S_{yx}$
+and $S_{zz}$) have been measured to 30 T, beyond the anomalous low temperature,
+field-induced transition at 22.5 T. We find a significant anisotropy in the
+MTEP signal, and also observe large quantum oscillations associated with the de
+Haas - van Alphen effect. The anisotropy indicates that the ground state
+properties are clearly driven by mechanisms that occur along specific
+directions for the in-plane electronic structure. Both transverse and
+longitudinal magnetothermopower show asymptotic behavior in field, which can be
+explained in terms of magnetic breakdown of compensated closed orbits.",0104447v1
+2001-04-27,The Magnetic Susceptibility of Non-Interacting Nanoparticles,"We have calculated the low-field magnetic susceptibility $\chi$ of a system
+consisting of non-interacting mono-dispersed nanoparticles using a classical
+statistical approach. The model makes use of the assumption that the axes of
+symmetry of all nanoparticles are aligned and oriented at a certain angle
+$\psi$ with respect to the external magnetic field. An analytical expression
+for the temperature dependence of the susceptibility $\chi(T)$ above the
+blocking temperature is obtained. The derived expression is a generalization of
+the Curie law for the case of anisotropic magnetic particles. We show that the
+normalized susceptibility is a universal function of the ratio of the
+temperature over the anisotropy constant for each angle $\psi$. In the case
+that the easy-axis is perpendicular to the magnetic field the susceptibility
+has a maximum. The temperature of the maximum allows one to determine the
+anisotropy energy.",0104539v1
+2001-06-08,Anisotropic Superconductivity in Epitaxial MgB2 Films,"High-quality epitaxial MgB2 thin films prepared by pulsed laser deposition
+with Tc = 39 K offer the opportunity to study the anisotropy and robustness of
+the superconducting state in magnetic fields. We measure the in-plane
+electrical resistivity of the films in magnetic fields to 60T and estimate the
+superconducting upper critical field Hc(0) = 24 +- 3 T for field oriented along
+the c-axis, and Hab(0) = 30 +- 2 T for field in the plane of the film. We find
+the zero-temperature coherence lengths xi_c(0) = 30 A and xi_ab(0) = 37 A to be
+shorter than the calculated electronic mean free path l = 100 +- 50 A, which
+places our films in the clean limit. The observation of such large upper
+critical fields from clean limit samples, coupled with the relatively small
+anisotropy, provides strong evidence of the viability of MgB2 as a
+technologically important superconductor.",0106146v1
+2001-06-27,"Determination of superconducting anisotropy from magnetization data on random powders as applied to LuNi$_2$B$_2$C, YNi$_2$B$_2$C and MgB$_2$","The recently discovered intermetallic superconductor MgB2 appears to have a
+highly anisotopic upper critical field with Hc2(max)/Hc2(min} = \gamma > 5. In
+order to determine the temperature dependence of both Hc2(max) and Hc2(min) we
+propose a method of extracting the superconducting anisotropy from the
+magnetization M(H,T) of randomly oriented powder samples. The method is based
+on two features in dM/dT the onset of diamagnetism at Tc(max), that is commonly
+associated with Hc2, and a kink in dM/dT at a lower temperature Tc(min).
+Results for LuNi2B2C and YNi2B2C powders are in agreement with anisotropic Hc2
+obtained from magneto-transport measurements on single crystals. Using this
+method on four different types of MgB2 powder samples we are able to determine
+Hc2(max)(T) and Hc2(min)(T) with \gamma \approx 6.",0106577v1
+2001-07-02,Growth of c-oriented MgB2 thin films by Pulsed Laser Deposition: structural characterization and electronic anisotropy,"MgB2 thin films were deposited using Pulsed Laser Deposition (PLD) and
+ex-situ annealing in Mg atmosphere. The films presented critical temperatures
+up to 36K and turned out to be preferentially c-oriented both on Al2O3 (r-cut)
+and MgO(100) substrates. Synchrotron analyses gave also some indications of in
+plane texturing. The films exhibit very fine grain size (1200angstromin the
+basal plane and 100angstrom along c-axis) but the general resistivity behavior
+and the remarkable extension of the irreversible region confirm that the grains
+boundaries are not barriers for supercurrents. Upper critical field
+measurements with the magnetic field perpendicular and parallel with respect to
+the film surface evidenced a field anisotropy ratio of 1.8. The Hc2 values are
+considerably higher with respect to the bulk ones, namely when the field lies
+in the basal plane, and the field-temperature phase diagram for the two
+magnetic field orientations suggest the possibility of strongly enhancing the
+pinning region by means of texturing.",0107031v1
+2001-07-11,The Superconducting Gap in MgB_2: Electronic Raman Scattering Measurements of Single Crystals,"Polarisation-resolved Raman scattering measurements were performed on MgB_2
+single crystals to determine the magnitude, symmetry and temperature dependence
+of the superconducting gap. A single sharp peak due to Cooper pair breaking
+appears in the electronic continuum below Tc, reaching an average maximum Raman
+shift of 105 +/- 1 cm^{-1} (2 Delta(0) / k_{B}Tc = 3.96 +/- 0.09) and showing
+up to 5 cm^{-1} anisotropy between polarised and depolarised spectra. The
+temperature dependence of 2 Delta follows that predicted from BCS theory, while
+the anisotropy decreases with decreasing temperature. It is concluded that the
+Raman results are consistent with a slightly anisotropic s-wave gap in a
+conventional BCS superconductor.",0107216v2
+2001-07-23,Surface-induced magnetic anisotropy for impurity spins in granular AuFe films,"The theory of the surface-induced anisotropy is extended to the case of
+granular films of dilute magnetic alloys. Since the surface-induced blocking of
+a magnetic-impurity spin appears to be very sensitive to the specific
+polycrystalline structure, we speculate that the apparent discrepancy between
+the experimental results of different groups for the size dependence of the
+Kondo resistivity can be linked to different microstructure of the samples. We
+apply our model to calculate the magnetization of impurity spins in small AuFe
+grains and to interpret the experimental data on the anomalous Hall effect in
+thin Fe doped Au films.",0107460v1
+2001-08-08,Magnetic anisotropy of the spin ice compound Dy2Ti2O7,"We report magnetization and ac susceptibility of single crystals of the spin
+ice compound Dy2Ti2O7. Saturated moments at 1.8 K along the charasteristic axes
+[100] and [110] agree with the expected values for an effective ferromagnetic
+nearest-neighbor Ising pyrochlore with local <111> anisotropy, where each
+magnetic moment is constrained to obey the `ice-rule'. At high enough magnetic
+fields along the [111] axis, the saturated moment exhibits a beaking of the
+ice-rule; it agrees with the value expected for a three-in one-out spin
+configuration. Assuming the realistic magnetic interaction between Dy ions
+given by the dipolar spin ice model, we completely reproduce the results at 2 K
+by Monte Carlo calculations. However, down to at least 60 mK, we have not found
+any experimental evidence of the long-range magnetic ordering predicted by this
+model to occur at around 180 mK. Instead, we confirm the spin freezing of the
+system below 0.5 K.",0108129v1
+2001-08-19,Critical thermodynamics of three-dimensional MN-component field model with cubic anisotropy from higher-loop εexpansion,"The critical thermodynamics of an $MN$-component field model with cubic
+anisotropy relevant to the phase transitions in certain crystals with
+complicated ordering is studied within the four-loop $\ve$ expansion using the
+minimal subtraction scheme. Investigation of the global structure of RG flows
+for the physically significant cases M=2, N=2 and M=2, N=3 shows that the model
+has an anisotropic stable fixed point with new critical exponents. The critical
+dimensionality of the order parameter is proved to be equal to
+$N_c^C=1.445(20)$, that is exactly half its counterpart in the real hypercubic
+model.",0108298v1
+2001-08-27,Electron Spin Resonance in S=1/2 antiferromagnetic chains,"A systematic field-theory approach to Electron Spin Resonance (ESR) in the
+$S=1/2$ quantum antiferromagnetic chain at low temperature $T$ (compared to the
+exchange coupling $J$) is developed. In particular, effects of a transverse
+staggered field $h$ and an exchange anisotropy (including a dipolar
+interaction) $\delta$ on the ESR lineshape are discussed. In the lowest order
+of perturbation theory, the linewidth is given as $\propto Jh^2/T^2$ and
+$\propto (\delta/J)^2 T$, respectively. In the case of a transverse staggered
+field, the perturbative expansion diverges at lower temperature;
+non-perturbative effects at very low temperature are discussed using exact
+results on the sine-Gordon field theory. We also compare our field-theory
+results with the predictions of Kubo-Tomita theory for the high-temperature
+regime, and discuss the crossover between the two regimes. It is argued that a
+naive application of the standard Kubo-Tomita theory to the
+Dzyaloshinskii-Moriya interaction gives an incorrect result. A rigorous and
+exact identity on the polarization dependence is derived for certain class of
+anisotropy, and compared with the field-theory results.",0108424v2
+2001-08-30,Spin dynamics of Sr_14Cu_24O_41 two-leg ladder studied by Raman spectroscopy,"The two-magnon (2M) excitation at 3000 cm-1 in Sr_14Cu_24O_41 two-leg ladder
+is studied by Raman scattering. A slight anisotropy of the superexchange
+coupling J_{\perp}/J_{||} \approx 0.8 with J_{||} = 110 \pm 20 meV is proposed
+from the analysis of the magnetic scattering. The resonant coupling across the
+charge transfer gap increases the 2M intensity by orders of magnitude. The
+anisotropy of Raman scattering is dependent upon the excitation energy. The 2M
+relaxation is found to be correlated with the temperature dependent electronic
+Raman continuum at low frequencies.",0108507v2
+2001-09-26,Transport properties of c-oriented MgB2 thin films grown by Pulsed Laser Deposition,"The electronic anisotropy in MgB2, which arises from its layered crystal
+structure is not completely clear until now. High quality c-oriented films
+offer the opportunity of studying such property. MgB2 thin films were deposited
+by using two methods both based on room temperature precursor deposition (by
+Pulsed Laser Ablation) and ex-situ annealing in Mg atmosphere. The two methods
+differ for the starting targets: stoichiometric MgB2 in one case and Boron in
+the other. The two films presented in this paper are grown by means of the two
+techniques on MgO substrates and are both c-oriented; they present TC values of
+31.5 and 37.4 K respectively. Upper critical field measurements, up to 9T, with
+the magnetic field in perpendicular and parallel directions in respect to the
+film surface evidenced anisotropy ratios of 1.8 and 1.4 respectively. In this
+paper we will discuss this remarkable and surprising difference also in
+comparison with the literature data.",0109481v1
+2001-09-28,Anisotropy in c-oriented MgB2 thin films grown by Pulsed Laser Deposition,"The electronic anisotropy in MgB2, is still a not completely clear topic;
+high quality c-oriented films are suitable systems to investigate this
+property. In this work we present our results on MgB2 superconducting thin
+films grown on MgO and sapphire substrates. The films are deposited in high
+vacuum, at room temperature, by Laser Ablation, starting from two different
+targets: pure Boron and stoichiometric MgB2. In both cases, to obtain and
+crystallize the superconducting phase, an ex-situ annealing in magnesium vapor
+is needed. The films were characterized by Synchrotron radiation diffraction
+measurements; the films turned out to be strongly c-oriented, with the c-axis
+perpendicular to the film surface and an influence of the substrate on
+crystallographic parameters is observed. Resisivity measurements with the
+magnetic field perpendicular and parallel directions to the film surface
+evidenced an anisotropic upper critical field behavior. The Hc2 ratios (h)
+resulted in the range 1.2-1.8; this difference will be discussed also in
+comparison with the literature data.",0109536v1
+2001-11-30,Electron Paramagnetic Resonance Linewidths and Lineshapes for the Molecular Magnets Fe8 and Mn12,"We study theoretically Electron Paramagentic Resonance (EPR) linewidths for
+single crystals of the molecular magnets Fe$_8$ and Mn$_{12}$ as functions of
+energy eigenstates $M_s$, frequency, and temperature when a magnetic field
+along the easy axis is swept at fixed excitation frequency. This work was
+motivated by recent EPR experiments. To calculate the linewidths, we use
+density-matrix equations, including dipolar interactions and distributions of
+the uniaxial anisotropy parameter $D$ and the Land\'{e} $g$ factor. Our
+calculated linewidths agree well with the experimental data. We also examine
+the lineshapes of the EPR spectra due to local rotations of the magnetic
+anisotropy axes caused by defects in samples. Our preliminary results predict
+that this effect leads to asymmetry in the EPR spectra.",0111589v2
+2002-02-08,Anisotropic Superconducting Properties of MgB2 Single Crystals,"In-plane electrical transport properties of MgB2 single crystals grown under
+high pressure of 4-6 GPa and temperature of 1400-1700oC in Mg-B-N system have
+been measured. For all specimens we found sharp superconducting transition
+around 38.1-38.3K with transition width within 0.2-0.3K. Estimated resistivity
+value at 40K is about 1 mkOhmcm and resistivity ratio R(273K)/R(40K) of about
+4.9. Results of measurements in magnetic field up to 5.5T perpendicular to Mg
+and B planes and up to 9T in parallel orientation show temperature dependent
+anisotropy of the upper critical field with anisotropy ratio increasing from
+2.2 close to Tc up to about 3 below 30K. Strong deviation of the angular
+dependence of Hc2 from anisotropic mass model has been also found.",0202133v1
+2002-03-06,Novel anisotropy in the superconducting gap structure of Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} probed by quasiparticle heat transport,"Since the nature of pairing interactions is manifested in the superconducting
+gap symmetry, the exact gap structure, particularly any deviation from the
+simple d_{x^2-y^2} symmetry, would help elucidating the pairing mechanism in
+high-T_c cuprates. Anisotropic heat transport measurement in
+Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} (Bi-2212) reveals that the quasiparticle
+populations are different for the two nodal directions and thus the gap
+structure must be uniquely anisotropic, suggesting that pairing is governed by
+interactions with a rather complicated anisotropy. Intriguingly, it is found
+that the ""plateau"" in the magnetic-field dependence of the thermal conductivity
+is observed only in the b-axis transport.",0203106v1
+2002-03-07,The Onset of Anisotropic Transport of Two-Dimensional Electrons in High Landau Levels: An Isotropic-to-Nematic Liquid Crystal Phase Transition?,"The recently discovered anisotropy of the longitudinal resistance of
+two-dimensional electrons near half filling of high Landau levels is found to
+persist to much higher temperatures T when a large in-plane magnetic field B||
+is applied. Under these conditions we find that the longitudinal resistivity
+scales quasi-linearly with B||/T. These observations support the notion that
+the onset of anisotropy at B||=0 does not reflect the spontaneous development
+of charge density modulations but may instead signal an isotropic-to-nematic
+liquid crystal phase transition.",0203174v1
+2002-03-15,Superconducting Transition and Phase Diagram of Single Crystal MgB2,"The superconducting phase diagram of MgB2 was determined from magnetization,
+magneto-transport and the first single-crystal specific heat measurements. A
+zero-temperature in-plane coherence length of 8 nm is determined. The
+superconducting anisotropy increases from a value around 2 near Tc to above 4.5
+at 22 K. For H||c a pronounced peak effect in the critical current occurs at
+the upper critical field. Evidence for a surface superconducting state is
+presented for H||c which might account for the wide spread in reported values
+of the anisotropy.",0203337v2
+2002-03-27,"Transport critical current, anisotropy, irreversibility fields and exponential n factors in Fe sheathed MgB2 tapes","The influence of the initial MgB2 grain size on critical current density,
+upper critical fields and irreversibility has been studied on Fe sheathed
+monofilamentary MgB2 tapes prepared by the Powder-In-Tube technique. The effect
+of the reduction of MgB2 grain size by ball milling was mainly to enhance both
+the critical current density, jc, and the irreversibility field, while the
+upper critical field remained unchanged. The anisotropy ratio of the upper
+critical field between magnetic fields parallel and perpendicular the tape
+surface was determined to 1.3, reflecting a deformation induced texture. A good
+agreement has been found between resistive and inductive jc values, measured at
+various temperatures. At 25K and 1 T, jc values close to 105 A/cm2 were
+measured. The exponential n factor of the resistive transition was found to be
+quite high at low fields, and decrease linearly from 60 at 4T to 10 at 8.5T.",0203551v1
+2002-03-29,Anisotropic random resistor networks: a model for piezoresistive response of thick-film resistors,"A number of evidences suggests that thick-film resistors are close to a
+metal-insulator transition and that tunneling processes between metallic grains
+are the main source of resistance. We consider as a minimal model for
+description of transport properties in thick-film resistors a percolative
+resistor network, with conducting elements governed by tunneling. For both
+oriented and randomly oriented networks, we show that the piezoresistive
+response to an applied strain is model dependent when the system is far away
+from the percolation thresold, while in the critical region it acquires
+universal properties. In particular close to the metal-insulator transition,
+the piezoresistive anisotropy show a power law behavior. Within this region,
+there exists a simple and universal relation between the conductance and the
+piezoresistive anisotropy, which could be experimentally tested by common
+cantilever bar measurements of thick-film resistors.",0203612v1
+2002-04-12,Anisotropic s-wave superconductivity: comparison with experiments on MgB2 single crystals,"The recently discovered superconductivity in MgB2 has captured world
+attention due to its simple crystal structure and relatively high
+superconducting transition temperature Tc=39K. It appears to be generally
+accepted that it is phonon-mediated s-wave BCS-like superconductivity.
+Surprisingly, the strongly temperature dependent anisotropy of the upper
+critical field, observed experimentally in magnesium diboride single crystals,
+is still lacking a consistent theoretical explanation. We propose a simple
+single-gap anisotropic s-wave order parameter in order to compare its
+implications with the prediction of a multi-gap isotropic s-wave model. The
+quasiparticle density of states, thermodynamic properties, NMR spin-lattice
+relaxation rate, optical conductivity, and Hc2 anisotropy have been analyzed
+within this anisotropic s-wave model. We show that the present model can
+capture many aspects of the unusual superconducting properties of MgB2
+compound, though more experimental data appear to be necessary from single
+crystal MgB2.",0204272v3
+2002-04-12,Spatial dispersion in CaF$_2$ caused by the vicinity of an excitonic bound state,"The microscopic mechanism beyond the optical anisotropy of an ionic crystal
+which occurs for short wavelengths is investigated. The electron-hole, two
+particle propagator and its analytical behaviour close to the band edge of the
+one particle continuum plays a major role for the mechanism of this optical
+anisotropy. Especially for an ionic crystal the two particle bound state, the
+exciton, is of special importance. In this way we argue that the so called
+``intrinsic birefringence'' in CaF$_2$ is neither intrinsic to the material nor
+it is birefringence. Instead it is spatial dispersion caused by the vicinity of
+a dispersive optical absorption given by the excitonic bound state. We propose
+a model which connects the bound state dispersion with the band structure and a
+model potential for a screened coulomb interaction. Based on these
+considerations we predict a wavelength dependence of the dielectric function
+approaching close to the bound state level $\epsilon \sim (\lambda -
+\lambda_0)^{-1}$, where $\lambda_0$ is the wavelength of the excitonic bound
+state level.",0204282v1
+2002-04-30,Quantum Monte Carlo simulation of thin magnetic films,"The stochastic series expansion quantum Monte Carlo method is used to study
+thin ferromagnetic films, described by a Heisenberg model including local
+anisotropies. The magnetization curve is calculated, and the results compared
+to Schwinger boson and many-body Green's function calculations. A transverse
+field is introduced in order to study the reorientation effect, in which the
+magnetization changes from out-of-plane to in-plane. Since the approximate
+theoretical approaches above differ significantly from each other, and the
+Monte Carlo method is free of systematic errors, the calculation provides an
+unbiased check of the approximate treatments. By studying quantum spin models
+with local anisotropies, varying spin size, and a transverse field, we also
+demonstrate the general applicability of the recent cluster-loop formulation of
+the stochastic series expansion quantum Monte Carlo method.",0204629v1
+2002-05-15,Competition between anisotropy and superconductivity in organic and cuprate superconductors,"We analyze the empirical correlation between the zero temperature penetration
+depth $\lambda_{c}(0) $ and the corresponding normal state DC conductivity
+$\sigma_{c}^{DC}$, measured slightly above the transition temperature $T_{c}$,
+in different classes of quasi two-dimensional superconductors, including
+cuprates and organics. For this purpose we invoke the scaling theory of quantum
+and finite temperature critical phenomena. Important implications are:
+Superconductivity in the organic and cuprate superconductors is a genuine three
+dimensional (3D) phenomenon. The competition between anisotropy and
+superconductivity destroys the latter in the 2D limit even in the ground state.
+The data uncovers the flow to quantum criticality, including the 2D quantum
+superconductor to insulator (2D-QSI) and the 3D quantum superconductor to
+normal state (3D-QSN) transition. This flow gives a clear perspective of the
+regimes where quantum fluctuations are essential and mean-field treatments
+fail. Thus, a detailed account of the flow from mean-field to 2D-QSI
+criticality in organics and the crossover from the 2D-QSI to the 3D-QSN
+critical point in cuprates is a challenge for microscopic theories attempting
+to solve the puzzle of superconductivity in these materials.",0205304v1
+2002-05-17,Thermodynamic Properties of Weakly Anisotropic Disordered Magnetic Chains in the Large-S Limit,"we investigate the thermodynamic properties of weakly anisotropic disordered
+magnetic chains where the nearest-neighbor Heisenberg exchange coupling is the
+dominant spin-spin interaction. In addition to the exchange interaction, there
+is single-ion anisotropy with the direction of the easy axis being the same for
+all spins. The analysis is carried out in the limit S >> 1, where S denotes the
+ionic spin, and in the temperature range T << JaveS, where Jave is the average
+magnitude of the exchange interaction. It is assumed that the independent boson
+picture is appropriate so that the thermodynamic properties of the chain are
+those of a gas of weakly interacting magnons whose frequencies are obtained
+from linearized equations of motion for the spins. The =+/-J model is studied
+in detail with both random and non-random anisotropy. Particular emphasis is
+placed on the existence",0205372v1
+2002-05-27,Free fermion branches in some quantum spin models,"Extensive numerical analysis of the eigenspectra of the $SU_q(N)$ invariant
+Perk-Schultz Hamiltonian shows some simple regularities for a significant part
+of the eigenspectrum. Inspired by those results we have found two set of
+solutions of the associated nested Bethe-ansatz equations. The first set is
+obtained at a special value of the anisotropy ($q = \exp(i2\pi (N-1)/N)$) and
+describes in particular the ground state and nearby excitations as a sum of
+free-fermion quasienergies. The second set of solutions provides the energies
+in the sectors whose number $n_i$ of particles of distinct species ($i =0,
+>..., N-1$) are less or equal to the unity except for one of the species. For
+this last set we obtain the eigenspectra of a free fermion model for arbitrary
+values of the anisotropy.",0205567v1
+2002-06-11,Anisotropy and large magnetoresistance in narrow gap semiconductor FeSb2,"A study of the anisotropy in magnetic, transport and magnetotransport
+properties of FeSb2 has been made on large single crystals grown from Sb flux.
+Magnetic susceptibility of FeSb2 shows diamagnetic to paramagnetic crossover
+around 100K. Electrical transport along two axes is semiconducting whereas the
+third axis exhibits a metal - semiconductor crossover at temperature Tmin which
+is sensitive to current alignment and ranges between 40 and 80K. In H=70kOe
+semiconducting transport is restored for T<300K, resulting in large
+magnetoresistance [rho(70kOe)-rho(0)]/rho(0)=2200% in the crossover temperature
+range",0206190v1
+2002-06-13,Anisotropy of the Upper Critical Field and Critical Current in Single Crystal MgB$_2$,"We report on specific heat, high magnetic field transport and
+$ac-$susceptibility measurements on magnesium diboride single crystals. The
+upper critical field $H_{c2}$ for magnetic fields perpendicular and parallel to
+the Mg and B planes is presented for the first time in the entire temperature
+range. A very different temperature dependence has been observed in the two
+directions which yields to a temperature dependent anisotropy with $\Gamma
+\sim$ 5 at low temperatures and about 2 near $T_c$. A peak effect is observed
+in susceptibility measurements for $H \sim $2 T parallel to the $c-$axis and
+the critical current density presnts a sharp maximum for $H$ parallel to the
+ab-plane.",0206231v2
+2002-07-31,Transport anisotropy in biaxially strained La(2/3)Ca(1/3)MnO(3) thin films,"Due to the complex interplay of magnetic, structural, electronic, and orbital
+degrees of freedom, biaxial strain is known to play an essential role in the
+doped manganites. For coherently strained La(2/3)Ca(1/3)MnO(3) thin films grown
+on SrTiO(3) substrates, we measured the magnetotransport properties both
+parallel and perpendicular to the substrate and found an anomaly of the
+electrical transport properties. Whereas metallic behavior is found within the
+plane of biaxial strain, for transport perpendicular to this plane an
+insulating behavior and non-linear current-voltage characteristics (IVCs) are
+observed. The most natural explanation of this anisotropy is a strain induced
+transition from an orbitally disordered ferromagnetic state to an orbitally
+ordered state associated with antiferromagnetic stacking of ferromagnetic
+manganese oxide planes.",0207730v1
+2002-08-06,Spin order on pyrochlore lattices studied by the Self-Consistent Cluster Approach,"In this paper we present a study of magnetic order of quantum Heisenberg
+spins on pyrochlore type lattices: a lattice of corner sharing tetrahedra. We
+use the Cluster Variation Approximation with the tetrahedron as basic cluster.
+We find that in case of anti-ferromagnetic nearest--neighbour exchange there is
+no long--range spin order at any finite temperature for any spin s. For
+ferromagnetic exchange and s=1/2 the spin system remains in a non-magnetic
+phase for all temperatures, while for s > 1/2 there is a finite order
+temperature. We derive the ground state phase diagram as a function of exchange
+anisotropy and tetragonal anisotropy and find regions of re--entrant behaviour.
+Magnetic fields can induce one or more magnetic transitions. Schottky--like
+anomalies appear in the specific heat, with on top signs of re--entrant
+behaviour. The limits of this Cluster Variation Approximations are discussed.",0208119v1
+2002-08-07,Kinetics of photoinduced anisotropy in azopolymers: models and mechanisms,"We consider the effect of photoinduced optical anisotropy (POA) in
+azopolymers. Using a unified approach to the kinetics of photo-reorientation we
+discuss the assumptions underlying the known theoretical models of POA and
+formulate a tractable phenomenological model in terms of angular redistribution
+probabilities and order parameter correlation functions. The model takes into
+account biaxiality effects and long term stability of POA in azopolymers. It
+predicts that under certain conditions two different mechanisms,
+photoorientation and photoselection, will dominate POA depending on the
+wavelength of pumping light. By using available experimental data, we employ
+the model to compute dependencies of principal absorption coefficients on the
+illumination time. Our calculations clearly indicate the different regimes of
+POA and the numerical results are found to be in good agreement with the
+experimental data.",0208123v1
+2002-09-04,More Evidence for a Distribution of Tunnel Splittings in Mn$_{12}$-acetate,"In magnetic fields applied parallel to the anisotropy axis, the magnetization
+of Mn$_{12}$ has been measured in response to a field that is swept back and
+forth across the resonances corresponding to steps $N=4,5,...9$. The fraction
+of molecules remaining in the metastable well after each sweep through the
+resonance is inconsistent with expectations for an ensemble of identical
+molecules. The data are consistent instead with the presence of a broad
+distribution of tunnel splittings. A very good fit is obtained for a Gaussian
+distribution of the second-order anisotropy tunneling parameter $X_E=-\ln(\mid
+E\mid/2D)$. We show that dipolar shuffling is a negligible effect which cannot
+explain our data.",0209110v2
+2002-09-10,Scattering of electrons by impurities within the framework of two band model of order parameter anisotropy,"The impurity concentration dependence of superconducting transition
+temperature $T_c$ is studied within the framework of two band model of order
+parameter anisotropy. Both intraband and interband electron scattering by
+nonmagnetic and magnetic impurities are taken into account. It is demonstrated
+that at various values of model parameters both types of impurity concentration
+dependence of $T_c$ are possible: weak dependence typical of the model with
+s-wave order parameter and strong suppression of $T_c$ by impurities with
+critical impurity concentration at which $T_c=0$. It is found that in some
+cases there is a possibility of a rise of critical temperature with increasing
+impurity concentration. The obtained results are consistent with existing
+experimental data for the high-temperature superconductors.",0209233v1
+2002-09-12,Electron momentum density in yttrium,"A simultaneous analysis of high-resolution directional Compton profiles and
+two-dimensional angular correlation of positron annihilation experimental data
+has been performed by studying both a directional anisotropy of measured
+spectra and reconstructed densities. The results were compared with theoretical
+fully-relativistic augmented plane-wave calculations with and without including
+correlation effects. Estimated symmetry selection rules have allowed us to
+establish some values of Fermi momenta. Both experiments show exactly the same
+shape of the anisotropy of the momentum densities, in agreement with the band
+structure results. In the positron annihilation data electron-positron
+correlations are not seen while in both experiments electron-electron
+correlations are observed.",0209297v1
+2002-09-17,Ground State Phase Diagram of S=1 XXZ Chains with Uniaxial Single-Ion-Type Anisotropy,"One dimensional S=1 XXZ chains with uniaxial single-ion-type anisotropy are
+studied by numerical exact diagonalization of finite size systems. The
+numerical data are analyzed using conformal field theory, the level
+spectroscopy, phenomenological renormalization group and finite size scaling
+method. We thus present the first quantitatively reliable ground state phase
+diagram of this model. The ground states of this model contain the Haldane
+phase, large-D phase, N\'{e}el phase, two XY phases and the ferromagnetic
+phase. There are four different types of transitions between these phases: the
+Brezinskii-Kosterlitz-Thouless type transitions, the Gaussian type transitions,
+the Ising type transitions and the first order transitions. The location of
+these critical lines are accurately determined.",0209403v1
+2002-09-17,Anisotropic magnetic behavior of GdBa_2Cu_3O_{6+y} single crystals,"Magnetic properties of high-quality Al-free nonsuperconducting
+GdBa_2Cu_3O_{6+y} single crystals grown by flux method have been studied. The
+magnetic anisotropy below the N\'eel temperature T_N~2.3K corresponds to the
+direction of Gd^{3+} magnetic moments along the tetragonal c-axis. At T < T_N
+clear indications of spin-flop transitions for H||c have been observed on
+magnetization curves at H_{sf}~10kOe. Magnetic phase diagrams have been
+obtained for H||c as well as for H||ab. A pronounced anisotropy in the magnetic
+susceptibility (unexpected for Gd-based compounds) has been found above T_N.",0209404v1
+2002-09-24,Low Temperature Static and Dynamic Behaviour of the Easy-Axis Heisenberg Antiferromagnet on the Kagome Lattice,"The antiferromagnetic Heisenberg model with easy-axis exchange anisotropy on
+the Kagome lattice is studied by means of Monte Carlo simulations. From
+equilibrium properties, we find that the values of the critical exponents
+associated with the magnetization at the critical temperature $T_c$ vary with
+the magnitude of the anisotropy. On the other hand, the spin-spin
+autocorrelation functions have a stretched exponential behavior with a power
+law divergence of the relaxation time at a glass-like temperature $T_g \sim
+T_c$. From non-equilibrium dynamics at a fixed temperature below $T_g$, aging
+effects are found which obey the same scaling laws as in spin glasses and
+polymers.",0209568v2
+2002-10-18,Field-Induced Transition in the S=1 Antiferromagnetic Chain with Single-Ion Anisotropy in a Transverse Magnetic Field,"The field-induced transition in one-dimensional S=1 Heisenberg
+antiferromagnet with single-ion anisotropy in the presence of a transverse
+magnetic field is obtained on the basis of the Schwinger boson mean-field
+theory. The behaviors of the specific heat and susceptibility as functions of
+temperature as well as the applied transverse field are explored, which are
+found to be different from the results obtained under a longitudinal field. The
+anomalies of the specific heat at low temperatures, which might be an
+indicative of a field-induced transition from a Luttinger liquid phase to an
+ordered phase, are explicitly uncovered under the transverse field. A schematic
+phase diagram is proposed. The theoretical results are compared with
+experimental observations.",0210394v1
+2002-11-14,Magnetic relaxation and dipole-coupling-induced magnetization in nanostructured thin films during growth: A cluster Monte Carlo study,"For growing inhomogeneous thin films with an island nanostructure similar as
+observed in experiment, we determine the nonequilibrium and equilibrium
+remanent magnetization. The single-island magnetic anisotropy, the dipole
+coupling, and the exchange interaction between magnetic islands are taken into
+account within a micromagnetic model. A cluster Monte Carlo method is developed
+which includes coherent magnetization changes of connected islands. This causes
+a fast relaxation towards equilibrium for irregularly connected systems. We
+analyse the transition from dipole coupled islands at low coverages to a
+strongly connected ferromagnetic film at high coverages during film growth. For
+coverages below the percolation threshold, the dipole interaction induces a
+collective magnetic order with ordering temperatures of 1 - 10 K for the
+assumed model parameters. Anisotropy causes blocking temperatures of 10 - 100 K
+and thus pronounced nonequilibrium effects. The dipole coupling leads to a
+somewhat slower magnetic relaxation.",0211290v2
+2002-11-20,Nanoscale phase separation in $La_{0.7}Ca_{0.3}MnO_3$ films: evidence for the texture driven optical anisotropy,"The IR optical absorption (0.1-1.5 eV) in the $La_{0.7}Ca_{0.3}MnO_3$ films
+on LAO substrate exhibits the drastic temperature evolution of the spectral
+weight evidencing the insulator to metal transition. Single crystal films were
+found to reveal strong linear dichroism with anomalous spectral oscillations
+and fairly weak temperature dependence. Starting from the concept of phase
+separation, we develop the effective medium model to account for these effects.
+The optical anisotropy of the films is attributed to the texturization of the
+ellipsoidal inclusions of the quasimetal phase caused by a mismatch of the film
+and substrate and the twin texture of the latter.",0211430v1
+2002-11-22,Linear and Second-order Optical Response of the III-V Mono-layer Superlattices,"We report the first fully self-consistent calculations of the nonlinear
+optical properties of superlattices. The materials investigated are mono-layer
+superlattices with GaP grown on the the top of InP, AlP and GaAs (110)
+substrates. We use the full-potential linearized augmented plane wave method
+within the generalized gradient approximation to obtain the frequency dependent
+dielectric tensor and the second-harmonic-generation susceptibility. The effect
+of lattice relaxations on the linear optical properties are studied. Our
+calculations show that the major anisotropy in the optical properties is the
+result of strain in GaP. This anisotropy is maximum for the superlattice with
+maximum lattice mismatch between the constituent materials. In order to
+differentiate the superlattice features from the bulk-like transitions an
+improvement over the existing effective medium model is proposed. The
+superlattice features are found to be more pronounced for the second-order than
+the linear optical response indicating the need for full supercell calculations
+in determining the correct second-order response.",0211512v2
+2002-11-28,Investigation of surface critical behavior of semi-infinite systems with cubic anisotropy,"The critical behavior at the special surface transition and crossover
+bevavior from special to ordinary surface transition in semi-infinite
+n-component anisotropic cubic models are investigated by applying the field
+theoretic approach directly in d=3 dimensions up to the two-loop approximation.
+The crossover behavior for random semi-infinite Ising-like system, which is the
+nontrivial particular case of the cubic model in the limit $n\to 0$, is also
+investigated. The numerical estimates of the resulting two-loop series
+expansions for the critical exponents of the special surface transition,
+surface crossover critical exponent $\Phi$ and the surface critical exponents
+of the layer, $\alpha_{1}$, and local specific heats, $\alpha_{11}$, are
+computed by means of Pade and Pade-Borel resummation techniques. For $n<n_{c}$
+the system belongs to the universality class of the isotropic n-component
+model, while for $n>n_{c}$ the cubic fixed point is stable, where $n_{c}$ is
+the marginal spin dimensionality of the cubic model. The obtained results
+indicate that the surface critical behavior of semi-infinite systems with cubic
+anisotropy is characterized by new set of surface critical exponents for
+$n>n_{c}$.",0211654v1
+2003-01-30,Definitive spectroscopic determination of the transverse interactions responsible for the magnetic quantum tunneling in Mn12-acetate,"We present detailed angle-dependent single crystal electron paramagnetic
+resonance (EPR) data for field rotations in the hard plane of the S=10 single
+molecule magnet Mn12-acetate. A clear four-fold variation in the resonance
+positions may be attributed to an intrinsic fourth order transverse anisotropy
+(O44). Meanwhile, a four-fold variation of the EPR lineshapes confirms a
+recently proposed model wherein disorder associated with the acetic acid of
+crystallization induces a locally varying quadratic (rhombic) transverse
+anisotropy (O22). These findings explain most aspects of the magnetic quantum
+tunneling observed in Mn12-acetate.",0301599v2
+2003-03-06,Anisotropy and Ising-like transition of the S=5/2 two-dimensional Heisenberg antiferromagnet Mn-formate di-Urea,"Recently reported measurements of specific heat on the compound Mn-formate
+di-Urea (Mn-f-2U) by Takeda et al. [Phys. Rev. B 63, 024425 (2001)] are
+considered. As a model to describe the overall thermodynamic behavior of such
+compound, the easy-axis two-dimensional Heisenberg antiferromagnet is proposed
+and studied by means of the 'pure quantum self-consistent harmonic
+approximation' (PQSCHA). In particular it is shown that, when the temperature
+decreases, the compound exhibits a crossover from 2D-Heisenberg to 2D-Ising
+behavior, followed by a 2D-Ising-like phase transition, whose location allows
+to get a reliable estimate of the easy-axis anisotropy driving the transition
+itself. Below the critical temperature T_N=3.77 K, the specific heat is well
+described by the two-dimensional easy-axis model down to a temperature T*=1.47
+K where a T^3-law sets in, possibly marking a low-temperature crossover of
+magnetic fluctuations from two to three dimensions.",0303119v1
+2003-03-22,Photoinduced 3D orientational order in side chain liquid crystalline azopolymers,"We apply experimental technique based on the combination of methods dealing
+with principal refractive indices and absorption coefficients to study the
+photoinduced 3D orientational order in the films of liquid crystalline (LC)
+azopolymers. The technique is used to identify 3D orientational configurations
+of trans azobenzene chromophores and to characterize the degree of ordering in
+terms of order parameters. We study two types of LC azopolymers which form
+structures with preferred in-plane and out-of-plane alignment of
+azochromophores, correspondingly. Using irradiation with the polarized light of
+two different wavelengths we find that the kinetics of photoinduced anisotropy
+can be dominated by either photo-reorientation or photoselection mechanisms
+depending on the wavelength. We formulate the phenomenological model describing
+the kinetics of photoinduced anisotropy in terms of the isomer concentrations
+and the order parameter tensor. We present the numerical results for absorption
+coefficients that are found to be in good agreement with the experimental data.
+The model is also used to interpret the effect of changing the mechanism with
+the wavelength of the pumping light.",0303488v1
+2003-04-07,Transitions from small to large Fermi momenta in a one-dimensional Kondo lattice model,"We study a one-dimensional system that consists of an electron gas coupled to
+a spin-1/2 chain by Kondo interaction away from half-filling. We show that
+zero-temperature transitions between phases with ""small"" and ""large"" Fermi
+momenta can be continuous. Such a continuous but Fermi-momentum-changing
+transition arises in the presence of spin anisotropy, from a Luttinger liquid
+with a small Fermi momentum to a Kondo-dimer phase with a large Fermi momentum.
+We have also added a frustrating next-nearest-neighbor interaction in the spin
+chain to show the possibility of a similar Fermi-momentum-changing transition,
+between the Kondo phase and a spin-Peierls phase, in the spin isotropic case.
+This transition, however, appears to involve a region in which the two phases
+coexist.",0304129v3
+2003-04-08,Fermi surface topology and vortex state in MgB2,"Based on a detailed modeling of the Fermi surface topology of MgB2 we
+calculated the anisotropy of the upper critical field Bc2 within the two gap
+model. The sigma-band is modeled as a distorted cylinder and the pi-band as a
+half-torus, with parameters determined from bandstructure calculations. Our
+results show that the unusual strong temperature dependence of the Bc2
+anisotropy, that has been observed recently, can be understood due to the small
+c-axis dispersion of the cylindrical Fermi surface sheets and the small
+interband pairing interaction as obtained from bandstructure calculations. We
+calculate the magnetic field dependence of the density of states within the
+vortex state for field in c-axis direction and compare with recent measurements
+of the specific heat on MgB2 single crystals.",0304194v1
+2003-04-18,Detection of XY behaviour in weakly anisotropic quantum antiferromagnets on the square lattice,"We consider the Heisenberg antiferromagnet on the square lattice with S=1/2
+and very weak easy-plane exchange anisotropy; by means of the quantum Monte
+Carlo method, based on the continuous-time loop algorithm, we find that the
+thermodynamics of the model is highly sensitive to the presence of tiny
+anisotropies and is characterized by a crossover between isotropic and planar
+behaviour. We discuss the mechanism underlying the crossover phenomenon and
+show that it occurs at a temperature which is characteristic of the model. The
+expected Berezinskii-Kosterlitz-Thouless transition is observed below the
+crossover: a finite range of temperatures consequently opens for experimental
+detection of non-critical 2D XY behaviour. Direct comparison is made with
+uniform susceptibility data relative to the S=1/2 layered antiferromagnet
+Sr2CuO2Cl2.",0304438v1
+2003-04-25,Ising-like Spin Anisotropy and Competing Antiferromagnetic - Ferromagnetic Orders in GdBaCo_{2}O_{5.5} Single Crystals,"In RBaCo_{2}O_{5+x} compounds (R is rare earth), a
+ferromagnetic-antiferromagnetic competition is accompanied by a giant
+magnetoresistance. We study the magnetization of detwinned GdBaCo_{2}O_{5.5}
+single crystals, and find a remarkable uniaxial anisotropy of Co^{3+} spins
+which is tightly linked with the chain oxygen ordering in GdO_{0.5} planes.
+Reflecting the underlying oxygen order, CoO_2 planes also develop a spin-state
+order consisting of Co^{3+} ions in alternating rows of S=1 and S=0 states. The
+magnetic structure appears to be composed of weakly coupled ferromagnetic
+ladders with Ising-like moments, which gives a simple picture for
+magnetotransport phenomena.",0304578v1
+2003-05-06,Gigantic anisotropic uniaxial pressure effect on superconductivity within the CuO2 plane of La1.64Eu0.2Sr0.16CuO4 - strain control of stripe criticality,"The effect of uniaxial pressure on superconductivity was examined for a
+high-Tc cuprate La1.64Eu0.2Sr0.16CuO4, which is located at the boundary between
+the superconducting and stripe phases. We found remarkably large anisotropy of
+the uniaxial pressure effect not only between the in-plane and out-of-plane
+pressures but also within the CuO2-plane. When the pressure is applied along
+the tetragonal [110] direction, we found the largest pressure effect ever
+observed in cuprates, dTc/dP - 2.5 K/kbar, while the change of Tc was not
+appreciable when applied along [100]. This substantial in-plane anisotropy is
+attributed to an intimate link between the symmetry of the one-dimensional
+stripes and that of the strain produced within the CuO2 plane.",0305111v1
+2003-06-03,Phase separation effects in charge-ordered Pr0.5Ca0.5MnO3 thin film,"Compressed Pr0.5Ca0.5MnO3 films (250nm) deposited on LaAlO3 have been studied
+by Electron Spin Resonance technique under high frequency and high magnetic
+field. We show evidences for the presence of a ferromagnetic phase (FM)
+embedded in the charge-order phase (CO), in form of thin layers which size
+depends on the strength and orientation of the magnetic field (parallel or
+perpendicular to the substrate plane). This FM phase presents an easy plane
+magnetic anisotropy with an anisotropy constant 100 times bigger than typical
+bulk values. When the magnetic field is applied perpendicular to the substrate
+plane, the FM phase is strongly coupled to the CO phase whereas for the
+parallel orientation it keeps an independent ferromagnetic resonance even when
+the CO phase becomes antiferromagnetic.",0306075v1
+2003-06-20,Anisotropic transport in the two-dimensional electron gas in the presence of spin-orbit coupling,"In a two-dimensional electron gas as realized by a semiconductor quantum
+well, the presence of spin-orbit coupling of both the Rashba and Dresselhaus
+type leads to anisotropic dispersion relations and Fermi contours. We study the
+effect of this anisotropy on the electrical conductivity in the presence of
+fixed impurity scatterers. The conductivity also shows in general an anisotropy
+which can be tuned by varying the Rashba coefficient. This effect provides a
+method of detecting and investigating spin-orbit coupling by measuring
+spin-unpolarized electrical currents in the diffusive regime. Our approach is
+based on an exact solution of the two-dimensional Boltzmann equation and
+provides also a natural framework for investigating other transport effects
+including the anomalous Hall effect.",0306528v2
+2003-07-15,Relevance of space anisotropy in the critical behavior of m-axial Lifshitz points,"The critical behavior of $d$-dimensional systems with $n$-component order
+parameter $\bm{\phi}$ is studied at an $m$-axial Lifshitz point where a
+wave-vector instability occurs in an $m$-dimensional subspace ${\mathbb R}^m$
+($m{>}1$). Field theoretic renormalization group techniques are exploited to
+examine the effects of terms in the Hamiltonian that break the rotational
+symmetry of the Euclidean group ${\mathbb E}(m)$. The framework for considering
+general operators of second order in $\bm{\phi}$ and fourth order in the
+derivatives $\partial_\alpha $ with respect to the Cartesian coordinates
+$x_\alpha $ of ${\mathbb R}^m$ is presented. For the specific case of systems
+with cubic anisotropy, the effects of having an additional term,
+$\sum_{\alpha=1}^m(\partial_\alpha^2\bm{\phi})^2$, are investigated in an
+$\epsilon$ expansion about the upper critical dimension $d^{*}(m)=4+m/2$. Its
+associated crossover exponent is computed to order $\epsilon^2$ and found to be
+positive, so that it is a \emph{relevant} perturbation on a model isotropic in
+${\mathbb R}^m$.",0307355v2
+2003-07-16,Anisotropies of the lower and upper critical fields in MgB$_2$ single crystals,"The temperature dependence of the London penetration depth ($\lambda$) and
+coherence length ($\xi$) has been deduced from Hall probe magnetization
+measurements in high quality MgB$_2$ single crystals in the two main
+crystallographic directions. We show that, in contrast to conventional
+superconductors, MgB$_2$ is characterized by two different anisotropy
+parameters ($\Gamma_\lambda = \lambda_c/\lambda_{ab}$ and $\Gamma_\xi =
+\xi_{ab}/\xi_c$) which strongly differ at low temperature and merge at $T_c $.
+These results are in very good agreement with recent calculations in weakly
+coupled two bands suprerconductors (Phys. Rev. B, 66, 020509(R) (2002).",0307388v1
+2003-07-16,On $c=1$ critical phases in anisotropic spin-1 chains,"Quantum spin-1 chains may develop massless phases in presence of Ising-like
+and single-ion anisotropies. We have studied c=1 critical phases by means of
+both analytical techniques, including a mapping of the lattice Hamiltonian onto
+an O(2) nonlinear sigma model, and a multi-target DMRG algorithm which allows
+for accurate calculation of excited states. We find excellent quantitative
+agreement with the theoretical predictions and conclude that a pure Gaussian
+model, without any orbifold construction, describes correctly the low-energy
+physics of these critical phases. This combined analysis indicates that the
+multicritical point at large single-ion anisotropy does not belong to the same
+universality class as the Takhtajan-Babujian Hamiltonian as claimed in the
+past. A link between string-order correlation functions and twisting vertex
+operators, along the c=1 line that ends at this point, is also suggested.",0307396v1
+2003-07-23,Role of surface disorder on the magnetic properties and hysteresis of nanoparticles,"We present the results of Monte Carlo simulations of a model of a single
+maghemite ferrimagnetic nanoparticle including radial surface anisotropy
+distinct from that in the core with the aim to clarify what is its role on the
+magnetization processes at low temperatures. The low temperature equilibrium
+states are analized and compared to those of a ferromagnetic particle with the
+same lattice structure. We have found that the formation of hedgehog-like
+structures due to increased surface anisotropy is responsible for a change in
+the reversal mechanism of the particles.",0307584v1
+2003-07-23,Effect of crystalline disorder on magnetic switching in small magnetic cells,"I present a study of the influence of disorder in thin magnetic films on the
+switching behavior of small magnetic cells of well defined shape and size. The
+disorder considered arises from randomly oriented crystalline grains of
+different shape, size, and crystalline orientation which gives rise to locally
+fluctuating intrinsic anisotropy directions and strengths. The study comprises
+a theoretical investigation of a disordered Stoner Wohlfarth model, as well as
+micromagnetic simulations. I show that the fluctuations in the total anisotropy
+and therefore in the switching fields are controlled by a single dimensionless
+parameter. The theoretical findings are well confirmed by micromagnetic
+simulations of many different samples",0307593v1
+2003-07-29,Properties of low-lying excited manifolds in the Mn12 acetate,"Most experimental data on the single-molecule magnet Mn$_{12}$ acetate have
+been successfully explained by the assumption that the Mn$_{12}$ acetate has an
+effective ground-state spin of S=10. However, the effect of the low-lying
+excited manifolds caused by interactions between Mn spins has not been well
+understood. To investigate the features of the low-lying excited manifolds, the
+intramolecular exchange interactions are calculated using density-functional
+theory (DFT). With the calculated exchange parameters, the energy gap between
+the S=10 ground-state and the first excited-state manifold is calculated by
+diagonalization of the Heisenberg Hamiltonian. The upper limit on the energy
+gap is about 40.5 K which is likely to be overestimated due to incomplete
+treatment of the Coulomb potential within DFT. It is found that there are
+several S=9 low-energy excited-state manifolds above the S=10 ground-state
+manifold. The magnetic anisotropy barriers for the low-lying spin excitations
+are calculated using DFT. Based on the calculations, it is found that the
+anisotropy barriers for the low-lying excited manifolds are approximately the
+same as that for the ground-state manifold, which is applicable to other
+single-molecule magnets such as Mn$_4$.",0307707v1
+2003-08-21,Magnetization plateau and quantum phase transitions in a spin-orbital model,"A spin-orbital chain with different Land\'e $g$ factors and one-ion
+anisotropy is studied in the context of the thermodynamical Bethe ansatz. It is
+found that there exists a magnetization plateau resulting from the different
+Land\'e $g$ factors. Detailed phase diagram in the presence of an external
+magnetic field is presented both numerically and analytically. For some values
+of the anisotropy, the four-component system undergoes five consecutive quantum
+phase transitions when the magnetic field varies. We also study the
+magnetization in various cases, especially its behaviors in the vicinity of the
+critical points. For the SU(4) spin-orbital model, explicit analytical
+expressions for the critical fields are derived, with excellent accuracy
+compared with numerics.",0308443v1
+2003-09-24,Anomalous behavior of spin wave resonances in Ga_{1-x}Mn_{x}As thin films,"We report ferromagnetic and spin wave resonance absorption measurements on
+high quality epitaxially grown Ga_{1-x}Mn_{x}As thin films. We find that these
+films exhibit robust ferromagnetic long-range order, based on the fact that up
+to seven resonances are detected at low temperatures, and the resonance
+structure survives to temperatures close to the ferromagnetic transition. On
+the other hand, we observe a spin wave dispersion which is linear in mode
+number, in qualitative contrast with the quadratic dispersion expected for
+homogeneous samples. We perform a detailed numerical analysis of the
+experimental data and provide analytical calculations to demonstrate that such
+a linear dispersion is incompatible with uniform magnetic parameters. Our
+theoretical analysis of the ferromagnetic resonance data, combined with the
+knowledge that strain-induced anisotropy is definitely present in these films,
+suggests that a spatially dependent magnetic anisotropy is the most likely
+reason behind the anomalous behavior observed.",0309566v2
+2003-09-25,Three Dimensional Heisenberg Spin Glass Models with and without Random Anisotropy,"We reexamine the spin glass (SG) phase transition of the $\pm J$ Heisenberg
+models with and without the random anisotropy $D$ in three dimensions ($d = 3$)
+using complementary two methods, i.e., (i) the defect energy method and (ii)
+the Monte Carlo method. We reveal that the conventional defect energy method is
+not convincing and propose a new method which considers the stiffness of the
+lattice itself. Using the method, we show that the stiffness exponent $\theta$
+has a positive value ($\theta > 0$) even when $D = 0$. Considering the
+stiffness at finite temperatures, we obtain the SG phase transition temperature
+of $T_{\rm SG} \sim 0.19J$ for $D = 0$. On the other hand, a large scale MC
+simulation shows that, in contrary to the previous results, a scaling plot of
+the SG susceptibility $\chi_{\rm SG}$ for $D = 0$ is obtained using almost the
+same transiton temperature of $T_{\rm SG} \sim 0.18J$. Hence we believe that
+the SG phase transition occurs in the Heisenberg SG model in $d = 3$.",0309573v1
+2003-10-07,Precessional switching of thin nanomagnets: analytical study,"We study analytically the precessional switching of the magnetization of a
+thin macrospin. We analyze its response when subjected to an external field
+along its in-plane hard axis. We derive the exact trajectories of the
+magnetization. The switching versus non switching behavior is delimited by a
+bifurcation trajectory, for applied fields equal to half of the effective
+anisotropy field. A magnetization going through this bifurcation trajectory
+passes exactly along the hard axis and exhibits a vanishing characteristic
+frequency at that unstable point, which makes the trajectory noise sensitive.
+Attempting to approach the related minimal cost in applied field makes the
+magnetization final state unpredictable. We add finite damping in the model as
+a perturbative, energy dissipation factor. For a large applied field, the
+system switches several times back and forth. Several trajectories can be gone
+through before the system has dissipated enough energy to converge to one
+attracting equilibrium state. For some moderate fields, the system switches
+only once by a relaxation dominated precessional switching. We show that the
+associated switching field increases linearly with the damping parameter. The
+slope scales with the square root of the effective anisotropy. Our simple
+concluding expressions are useful to assess the potential application of
+precessional switching in magnetic random access memories.",0310147v1
+2003-10-08,Soft modes in the easy plane pyrochlore antiferromagnet,"Thermal fluctuations lift the high ground state degeneracy of the classical
+nearest neighbour pyrochlore antiferromagnet, with easy plane anisotropy,
+giving a first order phase transition to a long range ordered state. We show,
+from spin wave analysis and numerical simulation, that even below this
+transition a continuous manifold of states, of dimension N^{2/3} exist (N is
+the number of degrees of freedom). As the temperature goes to zero a further
+`order by disorder' selection is made from this manifold. The pyrochlore
+antiferromagnet Er_2Ti_2O_7, is believed to have an easy plane anisotropy and
+is reported to have the same magnetic structure. The latter is perhaps
+surprising, given that the dipole interaction lifts the degeneracy of the
+classical model in favour of a different structure. We interpret our results in
+the light of these facts.",0310185v2
+2003-10-15,Ultrafast Collective Dynamics in the Charge-Density-Wave Conductor K$_{0.3}$MoO$_{3}$,"Low-energy coherent charge-density wave excitations are investigated in blue
+bronze (K$_{0.3}$MoO$_{3}$) and red bronze (K$_{0.33}$MoO$_{3}$) by femtosecond
+pump-probe spectroscopy. A linear gapless, acoustic-like dispersion relation is
+observed for the transverse phasons with a pronounced anisotropy in
+K$_{0.33}$MoO$_{3}$. The amplitude mode exhibits a weak (optic-like) dispersion
+relation with a frequency of 1.67 THz at 30 K. Our results show for the first
+time that the time-resolved optical technique provides momentum resolution of
+collective excitations in strongly correlated electron systems.Low-energy
+coherent charge-density wave excitations are investigated in blue bronze
+(K$_{0.3}$MoO$_{3}$) and red bronze (K$_{0.33}$MoO$_{3}$) by femtosecond
+pump-probe spectroscopy. A linear gapless, acoustic-like dispersion relation is
+observed for the transverse phasons with a pronounced anisotropy in
+K$_{0.33}$MoO$_{3}$. The amplitude mode exhibits a weak (optic-like) dispersion
+relation with a frequency of 1.67 THz at 30 K. Our results show for the first
+time that the time-resolved optical technique provides momentum resolution of
+collective excitations in strongly correlated electron systems.",0310357v1
+2003-10-31,Varying critical percolation exponents on a multifractal support,"We study percolation as a critical phenomenon on a multifractal support. The
+scaling exponents of the the infinite cluster size ($\beta$ exponent) and the
+fractal dimension of the percolation cluster ($d_f$) are quantities that seem
+do not depend on local anisotropies. These two quantities have the same value
+as in the standard percolation in regular bidimensional lattices. On the other
+side, the scaling of the correlation length ($\nu$ exponent) unfolds new
+universality classes due to the local anisotropy of the critical percolation
+cluster. We use two critical exponents $\nu$ according to the percolation
+criterion for crossing the lattice in either direction or in both directions.
+Moreover $\nu$ is related to a parameter that characterizes the stretching of
+the blocks forming the tilling of the multifractal.",0310779v1
+2003-11-06,Magnetic relaxation in terms of microscopic energy barriers in a model of dipolar interacting nanoparticles,"The magnetic relaxation and hysteresis of a system of single domain particles
+with dipolar interactions are studied by Monte Carlo simulations. We model the
+system by a chain of Heisenberg classical spins with randomly oriented
+easy-axis and log-normal distribution of anisotropy constants interacting
+through dipole-dipole interactions. Extending the so-called $T\ln(t/\tau_0)$
+method to interacting systems, we show how to relate the simulated relaxation
+curves to the effective energy barrier distributions responsible for the
+long-time relaxation. We find that the relaxation law changes from
+quasi-logarithmic to power-law when increasing the interaction strength. This
+fact is shown to be due to the appearence of an increasing number of small
+energy barriers caused by the reduction of the anisotropy energy barriers as
+the local dipolar fields increase.",0311139v1
+2003-11-25,Spin models with random anisotropy and reflection symmetry,"We study the critical behavior of a general class of cubic-symmetric spin
+systems in which disorder preserves the reflection symmetry $s_a\to -s_a$,
+$s_b\to s_b$ for $b\not= a$. This includes spin models in the presence of
+random cubic-symmetric anisotropy with probability distribution vanishing
+outside the lattice axes. Using nonperturbative arguments we show the existence
+of a stable fixed point corresponding to the random-exchange Ising universality
+class. The field-theoretical renormalization-group flow is investigated in the
+framework of a fixed-dimension expansion in powers of appropriate quartic
+couplings, computing the corresponding $\beta$-functions to five loops. This
+analysis shows that the random Ising fixed point is the only stable fixed point
+that is accessible from the relevant parameter region. Therefore, if the system
+undergoes a continuous transition, it belongs to the random-exchange Ising
+universality class. The approach to the asymptotic critical behavior is
+controlled by scaling corrections with exponent $\Delta = - \alpha_r$, where
+$\alpha_r\simeq -0.05$ is the specific-heat exponent of the random-exchange
+Ising model.",0311576v1
+2003-12-12,Surface critical behavior of semi-infinite systems with cubic anisotropy at the ordinary transition,"The critical behavior at the ordinary transition in semi-infinite n-component
+anisotropic cubic models is investigated by applying the field theoretic
+approach in d=3 dimensions up to the two-loop approximation. Numerical
+estimates of the resulting two-loop series expansions for the critical
+exponents of the ordinary transition are computed by means of Pade resummation
+techniques. For $n<n_{c}$ the system belongs to the universality class of the
+isotropic n-component model, while for $n>n_{c}$ the cubic fixed point becomes
+stable, where $n_{c}<3$ is the marginal spin dimensionality of the cubic model.
+The obtained results indicate that the surface critical behavior of the
+semi-infinite systems with cubic anisotropy is characterized by a new set of
+surface critical exponents for $n>n_{c}$.",0312320v1
+2003-12-16,Anisotropic scaling in YBa2Cu3O7 crystals with columnar defects,"We explore the interplay between the mass anisotropy and the uniaxial pinning
+of tilted columnar defects (CD) in a YBa2Cu3O7 single crystal. At high
+temperatures T and fields H a sharp peak in the irreversible magnetization Mi
+at the direction of the tracks signals the presence of the CD. At low T such a
+peak is not observed, and the influence of the CD appears only as a
+perturbation to the angular dependence due to the anisotropy. We show that at
+low T and high H the uniaxial effects due to CD can be recovered by performing
+an anisotropic rescaling. As expected, this scaling fails at low H.",0312405v1
+2003-12-22,Anisotropic and Heterogeneous Polymerized Membranes,"In these lectures I discuss long-scale properties of fluctuating polymerized
+membranes in the presence of network anisotropy and random heterogeneities.
+Amazingly, even infinitesimal amount of these seemingly innocuous but
+physically important ingredients in the membrane's internal structure leads to
+a wealth of striking qualitatively new phenomena. Anisotropy leads to a
+``tubule'' phase that is intermediate in its properties and location on the
+phase diagram between previously discussed ``crumpled'' and ``flat'' phases. At
+low temperature, network heterogeneity generates conformationally glassy
+phases, with membrane normals exhibiting glass order analogous to spin-glasses.
+The common thread to these distinct membrane phases is that they exhibit
+universal anomalous elasticity, (singularly length-scale dependent elastic
+moduli, universal Poisson ratio, etc.), driven by thermal fluctuations and/or
+disorder and controlled by a nontrivial low-temperature fixed point.",0312567v1
+2004-01-26,Strong-coupling theory of magnetic-exciton-mediated superconductivity in UPd$_2$Al$_3$,"There is compelling evidence from inelastic-neutron-scattering and tunneling
+experiments that the heavy-fermion superconductor UPd$_2$Al$_3$ can be
+understood as a dual system consisting of magnetic excitons, arising from
+crystal-field-split U$^{4+}$ levels, coupled to delocalised f-electrons. We
+have computed the superconducting transition temperature and the mass
+renormalisation arising from a dual model with maximal spin anisotropy using a
+strong-coupling approach. We find an instability to two possible
+opposite-spin-pairing states with even- or odd-parity gap functions. Each has a
+line node perpendicular to the c-direction, in agreement with NMR
+relaxation-rate, specific-heat and thermal-conductivity measurements. In
+addition, both have total spin component $S_z$=0, compatible with the
+observation of a pronounced Knight shift and $H_{c2}$ Pauli limiting. For
+parameter values appropriate to UPd$_2$Al$_3$, we determine the dependence of
+the superconducting transition temperature $T_c$ on a phenomenological coupling
+constant $g$ and we investigate the associated mass enhancement and its
+anisotropy.",0401520v1
+2004-01-29,Influence of Ising-anisotropy on the zero-temperature phase transition in the square lattice spin-1/2 J-J' model,"We use a variational mean-field like approach, the coupled cluster method
+(CCM) and exact diagonalization to investigate the ground-state order-disorder
+transition for the square lattice spin-half XXZ model with two different
+nearest-neighbor couplings $J$ and $J'$. Increasing $J' > J$ the model shows in
+the isotropic Heisenberg limit a second-order transition from semi-classical
+N\'eel order to a quantum paramagnetic phase with enhanced local dimer
+correlations on the $J'$ bonds at about $J'_{c} \sim 2.5 ... 3 J$. This
+transition is driven by the quantum competition between $J'$ and $J$.
+Increasing the anisotropy parameter $\Delta> 1$ we diminish the quantum
+fluctuations and thus the degree of competition. As a result the transition
+point $J'_{c}$ is shifted to larger values. We find indications for a linear
+increase of $J'_{c}$ with $\Delta $, i.e. the transition disappears in the
+Ising limit $\Delta \to \infty$.",0401604v3
+2004-03-01,Anomalous Spin Dephasing in (110) GaAs Quantum Wells: Anisotropy and Intersubband Effects,"A strong anisotropy of electron spin decoherence is observed in GaAs/(AlGa)As
+quantum wells grown on (110) oriented substrate. The spin lifetime of spins
+perpendicular to the growth direction is about one order of magnitude shorter
+compared to spins along (110). The spin lifetimes of both spin orientations
+decrease monotonically above a temperature of 80 and 120 K, respectively. The
+decrease is very surprising for spins along (110) direction and cannot be
+explained by the usual Dyakonov Perel dephasing mechanism. A novel spin
+dephasing mechanism is put forward that is based on scattering of electrons
+between different quantum well subbands.",0403052v2
+2004-03-09,Theory of nonlinear optical properties of phenyl-substituted polyacetylenes,"In this paper we present a theoretical study of the third-order nonlinear
+optical properties of poly(diphenyl)polyacetylene (PDPA) pertaining to the
+third-harmonic-generation (THG) process. We study the aforesaid process in
+PDPA's using both the independent electron Hueckel model, as well as
+correlated-electron Pariser-Parr-Pople (P-P-P) model. The P-P-P model based
+calculations were performed using various configuration interaction (CI)
+methods such as the the multi-reference-singles-doubles CI (MRSDCI), and the
+quadruples-CI (QCI) methods, and the both longitudinal and the transverse
+components of third-order susceptibilities were computed. The Hueckel model
+calculations were performed on oligo-PDPA's containing up to fifty repeat
+units, while correlated calculations were performed for oligomers containing up
+to ten unit cells. At all levels of theory, the material exhibits highly
+anisotropic nonlinear optical response, in keeping with its structural
+anisotropy. We argue that the aforesaid anisotropy can be divided over two
+natural energy scales: (a) the low-energy response is predominantly
+longitudinal and is qualitatively similar to that of polyenes, while (b) the
+high-energy response is mainly transverse, and is qualitatively similar to that
+of trans-stilbene.",0403228v1
+2004-03-10,Doublon Growth in Solidification,"We present experiments on the doublon growth morphology in directional
+solidification. Samples used are succinonitrile with small amounts of
+poly(ethylene oxide), acetone, or camphor as the solute. Doublons, or
+symmetry-broken dendrites, are generic diffusion-limited growth structures
+expected at large undercooling and low anisotropy. Low anisotropy growth is
+achieved by selecting a grain near the $\{111\}$ plane leading to either
+seaweed (dense branching morphology) or doublon growth depending on
+experimental parameters. We find selection of doublons to be strongly dependent
+on solute concentration and sample orientation. Doublons are selected at low
+concentrations (low solutal undercooling) in contrast to the prediction of
+doublons at large thermal undercooling in pure materials. Doublons also exhibit
+preferred growth directions and changing the orientation of a specific
+doublonic grain changes the character and stability of the doublons. We observe
+transitions between seaweed and doublon growth with changes in concentration
+and sample orientation.",0403279v2
+2004-03-12,Consequences of spin-orbit coupling for the Bose-Einstein condensation of magnons,"In the first part we discuss how the BEC picture for magnons is modified by
+anisotropies induced by spin-orbit coupling. In particular we focus on the
+effects of antisymmetric spin interactions and/or a staggered component of the
+$g$ (gyromagnetic) tensor. Such terms lead to a gapped quasiparticle spectrum
+and a nonzero condensate density for all temperatures so that no phase
+transition occurs. We contrast this to the effect of crystal field anisotropies
+which are also induced by spin-orbit coupling. In the second part we study the
+field-induced magnetic ordering in TlCuCl$_3$ on a quantitative level. We show
+that the usual BEC picture does not allow for a good description of the
+experimental magnetisation data and argue that antisymmetric spin interactions
+and/or a staggered $g$ tensor component are still crucial, although both are
+expected to be tiny in this compound due to crystal symmetries. Including this
+type of interaction we obtain excellent agreement with experimental data.",0403311v2
+2004-03-23,Intrinsic charge transport on the surface of organic semiconductors,"The novel technique based on air-gap transistor stamps enabled realization of
+the intrinsic (not dominated by static disorder) transport of the
+electric-field-induced charge carriers on the surface of rubrene crystals over
+a wide temperature range. The signatures of the intrinsic transport are the
+anisotropy of the carrier mobility, mu, and the growth of mu with cooling. The
+anisotropy of mu vanishes in the activation regime at lower temperatures, where
+the charge transport becomes dominated by shallow traps. The deep traps,
+deliberately introduced into the crystal by X-ray radiation, increase the
+field-effect threshold without affecting the mobility. These traps filled above
+the field-effect threshold do not scatter the mobile polaronic carriers.",0403575v1
+2004-04-02,Magnetic susceptibility study of hydrated and non-hydrated NaxCoO2-yH2O single crystals,"We have measured the magnetic susceptibility of single crystal samples of
+non-hydrated NaxCoO2 (x ~ 0.75, 0.67, 0.5, and 0.3) and hydrated Na0.3CoO2-yH2O
+(y ~ 0, 0.6, 1.3). Our measurements reveal considerable anisotropy between the
+susceptibilities with H||c and H||ab. The derived anisotropic g-factor ratio
+(g_ab/g_c) decreases significantly as the composition is changed from the
+Curie-Weiss metal with x = 0.75 to the paramagnetic metal with x = 0.3. Fully
+hydrated Na0.3CoO2-1.3H2O samples have a larger susceptibility than
+non-hydrated Na0.3CoO2 samples, as well as a higher degree of anisotropy. In
+addition, the fully hydrated compound contains a small additional fraction of
+anisotropic localized spins.",0404061v3
+2004-04-16,Momentum anisotropy of the scattering rate in cuprate superconductors,"We examine the momentum and energy dependence of the scattering rate of the
+high temperature cuprate superconductors using angle resolved photoemission
+spectroscopy. The scattering rate is of the form a + b*w. The inelastic
+coefficient b is found to be isotropic. The elastic term, a, however, is found
+to be highly anisotropic in the pseudogap phase of optimal doped samples, with
+an anisotropy which correlates with that of the pseudogap. This can be
+contrasted with heavily overdoped samples, which show an isotropic scattering
+rate in the normal state.",0404385v1
+2004-05-04,Islands in the Stream: Electromigration-Driven Shape Evolution with Crystal Anisotropy,"We consider the shape evolution of two-dimensional islands on a crystal
+surface in the regime where mass transport is exclusively along the island
+edge. A directed mass current due to surface electromigration causes the island
+to migrate in the direction of the force. Stationary shapes in the presence of
+an anisotropic edge mobility can be computed analytically when the capillary
+effects of the line tension of the island edge are neglected, and conditions
+for the existence of non-singular stationary shapes can be formulated. In
+particular, we analyse the dependence of the direction of island migration on
+the relative orientation of the electric field to the crystal anisotropy, and
+we show that no stationary shapes exist when the number of symmetry axes is
+odd. The full problem including line tension is solved by time-dependent
+numerical integration of the sharp-interface model. In addition to stationary
+shapes and shape instability leading to island breakup, we also find a regime
+where the shape displays periodic oscillations.",0405068v1
+2004-05-17,Internal state of granular assemblies near random close packing,"The structure of random sphere packings in mechanical equilibrium in
+prescribed stress states, as studied by molecular dynamics simulations,
+strongly depends on the assembling procedure. Frictionless packings in the
+limit of low pressure are devoid of dilatancy, and consequently share the same
+random close packing density, but exhibit fabric anisotropy related to stress
+anisotropy. Efficient compaction methods can be viewed as routes to circumvent
+the influence of friction. Simulations designed to resemble two such
+procedures, lubrication and vibration (or ``tapping'') show that the resulting
+granular structures differ, the less dense one having, remarkably, the larger
+coordination number. Density, coordination number and fabric can thus vary
+independently. Calculations of elastic moduli and comparisons with experimental
+results suggest that measurable elastic properties provide information on those
+important internal state variables.",0405358v1
+2004-05-20,Influence of non-local exchange on RKKY interactions in III-V diluted magnetic semiconductors,"The RKKY interaction between substitutional Mn local moments in GaAs is both
+spin-direction-dependent and spatially anisotropic. In this Letter we address
+the strength of these anisotropies using a semi-phenomenological tight-binding
+model which treats the hybridization between Mn d-orbitals and As p-orbitals
+perturbatively and accounts realistically for the non-local exchange
+interaction between their spins. We show that exchange non-locality,
+valence-band spin-orbit coupling, and band-structure anisotropy all play a role
+in determining the strength of both effects. We use these results to estimate
+the degree of ground-state magnetization suppression due to frustrating
+interactions between randomly located Mn ions.",0405484v2
+2004-05-27,"Influence of gap structures to specific heat in oriented magnetic fields: Application to the orbital dependent superconductor, Sr$_2$RuO$_4$","We discuss influence of modulation of gap function and anisotropy of Fermi
+velocity to field angle dependences of upper critical field, $H_{c2}$, and
+specific heat, $C$, on the basis of the approximate analytic solution in the
+quasiclassical formalism. Using 4-fold modulation of the gap function and the
+Fermi velocity in the single-band model, we demonstrate field and temperature
+dependence of oscillatory amplitude of $H_{c2}$ and $C$. We apply the method to
+the effective two-band model to discuss the gap structure of Sr$_2$RuO$_4$,
+focusing on recent field angle-resolved experiments. It is shown that the gap
+structures with the intermediate magnitude of minima in $[100]$ direction for
+$\gamma$ band, and tiny minima of gaps in $[110]$ directions for $\alpha$ and
+$\beta$ bands give consistent behaviors with experiments. The interplay of the
+above two gaps also explains the anomalous temperature dependence of in-plane
+$H_{c2}$ anisotropy, where the opposite contribution from the passive
+$\alpha\beta$ band is pronounced near $T_c$.",0405631v1
+2004-06-29,"Aging, rejuvenation and memory phenomena in spin glasses","In this paper, we review several important features of the out-of-equilibrium
+dynamics of spin glasses. Starting with the simplest experiments, we discuss
+the scaling laws used to describe the isothermal aging observed in spin glasses
+after a quench down to the low temperature phase. We report in particular new
+results on the sub-aging behaviour of spin glasses. We then discuss the
+rejuvenation and memory effects observed when a spin glass is submitted to
+temperature variations during aging, from the point of view of both energy
+landscape pictures and of real space pictures. We highlight the fact that both
+approaches point out the necessity of hierarchical processes involved in aging.
+Finally, we report an investigation of the effect of small temperature
+variations on aging in spin glass samples with various anisotropies which
+indicates that this hierarchy depends on the spin anisotropy.",0406721v2
+2004-07-10,Anisotropy of the paramagnetic susceptibility in LaTiO$_{3}$: The electron-distribution picture in the ground state,"The energy-level scheme and wave functions of the titanium ions in
+LaTiO$_{3}$ are calculated using crystal-field theory and spin-orbit coupling.
+The theoretically derived temperature dependence and anisotropy of the magnetic
+susceptibility agree well with experimental data obtained in an untwinned
+single crystal. The refined fitting procedure reveals an almost isotropic
+molecular field and a temperature dependence of the van Vleck susceptibility.
+The charge distribution of the 3d--electron on the Ti positions and the
+principle values of the quadrupole moments are derived and agree with NMR data
+and recent measurements of orbital momentum $<l>$ and crystal-field splitting.
+The low value of the ordered moment in the antiferromagnetic phase is
+discussed.",0407264v1
+2004-07-14,Motion of Contact Line of a Crystal Over the Edge of Solid Mask in Epitaxial Lateral Overgrowth,"Mathematical model that allows for direct tracking of the homoepitaxial
+crystal growth out of the window etched in the solid, pre-deposited layer on
+the substrate is described. The growth is governed by the normal (to the
+crystal-vapor interface) flux from the vapor phase and by the interface
+diffusion. The model accounts for possibly inhomogeneous energy of the mask
+surface and for strong anisotropies of crystal-vapor interfacial energy and
+kinetic mobility. Results demonstrate that the motion of the crystal-mask
+contact line slows down abruptly as radius of curvature of the mask edge
+approaches zero. Numerical procedure is suggested to overcome difficulties
+associated with ill-posedness of the evolution problem for the interface with
+strong energy anisotropy.
+  Keywords: Thin films, epitaxy, MOCVD, surface diffusion, interface dynamics,
+contact lines, rough surfaces, wetting, regularization of ill-posed evolution
+problems.",0407362v1
+2004-07-25,Triaxial Bright Solitons in Bose-Condensed Atomic Vapors,"The properties of triaxial bright solitons (TBSs) made of attractive
+Bose-Einstein condensed atoms under transverse anisotropic harmonic confinement
+are investigated by using a variational approach. We show that these metastable
+TBSs change their shape from cigar-like to disc-like by increasing the
+inter-atomic strength. Moreover, we find that the collective oscillations of a
+TBS strongly depend on the anisotropy parameter of the external potential. We
+calculate in detail the properties of TBS close to the collapse, which sets up
+at a critical value of the inter-atomic strength. This critical strength is
+maximal in the isotropic (axially symmetric) case and slightly reduces by
+increasing the anisotropy. Finally, we investigate the formation of multiple
+TBSs via modulational instability induced by a sudden change of the scattering
+length from positive to negative.",0407653v1
+2004-07-29,Magnetism of One-Dimensional Ni monoatomic chain on Au(110)-(1x2) surface,"Based on Density Functional Theory with no-collinear-magnetism formulations,
+we have calculated magnetic anisotropy of supported Ni chains. Our results
+indicate that the magnetic anisotropy is closely related to orbital quenching.
+The easiest magnetized axis changes from parallel to perpendicular to the Ni
+chains once they absorb on the surface. Our results for single absorbed 3d
+transition metal atom show that the surface relaxation enhances the orbital
+moments of left-end elements (Ti,V) and quenches the orbital moments of
+right-end elements (Fe,Co,Ni) on the Au(110)-(1$\times$2) surface. This is
+because Ti and V atom raise their position above the trough and Fe, Co, Ni atom
+trap more deeply in the trough after the surface relaxation.",0407748v4
+2004-07-29,Kondo Effect on Mesoscopic Scale (Review),"Following the discovery of the Kondo effect the bulk transport and magnetic
+behavior of the dilute magnetic alloys have been successfully described. In the
+last fifteen years new directions have been developed as the study of the
+systems of reduced dimensions and the artificial atoms so called quantum dots.
+In this review the first subject is reviewed starting with the scanning
+tunneling microscope (STM) study of a single magnetic impurity. The next
+subject is the reduction of the amplitude of the Kondo effect in samples of
+reduced dimension which was explained by the surface magnetic anisotropy which
+blocks the motion of the integer spin nearby the surface. The electron
+dephasing and energy relaxation experiments are discussed with the possible
+explanation including the surface anisotropy, where the situation in cases of
+integer and half-integer spins is very different. Finally, the present
+situation of the theory of dynamical structural defects is briefly presented
+which may lead to two-channel Kondo behavior.",0407766v1
+2004-08-12,Scattering of Carriers by Charged Dislocations in Semiconductors,"The scattering of carriers by charged dislocations in semiconductors is
+studied within the framework of the linearized Boltzmann transport theory with
+an emphasis on examining consequences of the extreme anisotropy of the
+scattering potential. A new closed-form approximate expression for the carrier
+mobility valid for all temperatures is proposed. The ratios of quantum and
+transport scattering times are evaluated after averaging over the anisotropy in
+the relaxation time. The value of the Hall scattering factor computed for
+charged dislocation scattering indicates that there may be a factor of two
+error in the experimental mobility estimates using the Hall data. An expression
+for the resistivity tensor when the dislocations are tilted with respect to the
+plane of transport is derived. Finally an expression for the isotropic
+relaxation time is derived when the dislocations are located within the sample
+with a uniform angular distribution.",0408256v2
+2004-08-25,Thermal transport of the XXZ chain in a magnetic field,"We study the heat conduction of the spin-1/2 XXZ chain in finite magnetic
+fields where magnetothermal effects arise. Due to the integrability of this
+model, all transport coefficients diverge, signaled by finite Drude weights.
+Using exact diagonalization and mean-field theory, we analyze the temperature
+and field dependence of the thermal Drude weight for various exchange
+anisotropies under the condition of zero magnetization-current flow. First, we
+find a strong magnetic field dependence of the Drude weight, including a
+suppression of its magnitude with increasing field strength and a non-monotonic
+field-dependence of the peak position. Second, for small exchange anisotropies
+and magnetic fields in the massless as well as in the fully polarized regime
+the mean-field approach is in excellent agreement with the exact
+diagonalization data. Third, at the field-induced quantum critical line between
+the para- and ferromagnetic region we propose a universal low-temperature
+behavior of the thermal Drude weight.",0408529v2
+2004-08-31,Influence of surface anisotropy on the hysteresis of magnetic nanoparticles,"We present the results of Monte Carlo simulations of the magnetic properties
+of individual spherical nanoparticles with the aim to explain the role played
+by surface anisotropy on their low temperature magnetization processes. Phase
+diagrams for the equilibrium configurations have been obtained, showing a
+change from quasi-uniform magnetization state to a state with hedgehog-like
+structures at the surface as $k_S$ increases. Through the simulated hysteresis
+loops and the analysis of spin configurations along them, we have identified a
+change in the magnetization reversal mechanism from quasi-uniform rotation at
+low $k_S$ values, to a non-uniform switching process at high $k_S$. Results for
+the dependence of the coercive field and remanence on $k_S$ and particle size
+are also reported.",0408678v1
+2004-09-07,Spin Dynamics of Layered Triangular Antiferromagnets with Uniaxial Anisotropy,"The spin dynamics of the semiclassical Heisenberg model with uniaxial
+anisotropy, on the layered triangular lattice with antiferromagnetic coupling
+for both intralayer nearest neighbor interaction and interlayer interaction is
+studied both in the ordered phase and in the paramagnetic phase, using the
+Monte Carlo-molecular dynamics technique. The important quantities calculated
+are the full dynamic structure function $S(\bf q, \omega)$, the chiral dynamic
+structure function $S_{chi}(\omega)$, the static order parameter and some
+thermodynamic quantities. Our results show the existence of propagating modes
+corresponding to both $S(\bf q, \omega)$ and $S_{chi}(\omega)$ in the ordered
+phase, supporting the recent conjectures. Our results for the static properties
+show the magnetic ordering in each layer to be of coplanar 3-sublattice type
+deviating from 120 degree structure. In the presence of magnetic trimerization
+however, we find the 3-sublattice structure to be weakened alongwith the
+tendency towards non-coplanarity of the spins.",0409151v1
+2004-09-08,Electronic structure and magnetic anisotropy for nickel-based molecular magnets,"Recent magnetic measurements on tetra-nickel molecular magnets
+[Ni(hmp)(ROH)Cl]$_4$, where R=CH$_3$, CH$_2$CH$_3$, or
+(CH$_2$)$_2$C(CH$_3$)$_3$ and hmp$^-$ is the monoanion of
+2-hydroxymethylpyridine, revealed a strong exchange bias prior to the external
+magnetic field reversal as well as anomalies in electron paramagnetic resonance
+peaks at low temperatures. To understand the exchange bias and observed
+anomalies, we calculate the electronic structure and magnetic properties for
+the Ni$_4$ molecules with the three different ligands, employing
+density-functional theory. Considering the optimized structure with possible
+collinear spin configurations, we determine a total spin of the lowest-energy
+state to be S=0, which does not agree with experiment. We also calculate
+magnetic anisotropy barriers for all three types of Ni$_4$ molecules to be in
+the range of 4-6 K.",0409207v1
+2004-09-13,Thermal and magnetic properties of integrable spin-1 and spin-3/2 chains with applications to real compounds,"The ground state and thermodynamic properties of spin-1 and spin-3/2 chains
+are investigated via exactly solved su(3) and su(4) models with physically
+motivated chemical potential terms. The analysis involves the Thermodynamic
+Bethe Ansatz and the High Temperature Expansion (HTE) methods. For the spin-1
+chain with large single-ion anisotropy, a gapped phase occurs which is
+significantly different from the valence-bond-solid Haldane phase. The
+theoretical curves for the magnetization, susceptibility and specific heat are
+favourably compared with experimental data for a number of spin-1 chain
+compounds. For the spin-3/2 chain a degenerate gapped phase exists starting at
+zero external magnetic field. A middle magnetization plateau can be triggered
+by the single-ion anisotropy term. Overall, our results lend further weight to
+the applicability of integrable models to the physics of low-dimensional
+quantum spin systems. They also highlight the utility of the exact HTE method.",0409311v1
+2004-09-16,Electronic state around vortex in a two-band superconductor,"Based on the quasiclassical theory, we investigate the vortex state in a
+two-band superconductor with a small gap on a three dimensional Fermi surface
+and a large gap on a quasi-two dimensional one, as in MgB_2. The field
+dependence of zero-energy density of states is compared for fields parallel and
+perpendicular to the ab plane, and the anisotropy of the vortex core shape is
+discussed for a parallel field. The Fermi surface geometry of two-bands,
+combining the effect of the normal-like electronic state on the small gap band
+at high fields, produces characteristic behavior in the anisotropy of c- and
+ab-directions.",0409413v1
+2004-09-22,"Theory of anisotropic s-wave superconductivity with point-node like gap minima: analysis of (Y,Lu)Ni_2B_2C","Recent intensive experimental studies revealed that (Y,Lu)Ni$_2$B$_2$C is an
+anisotropic s-wave superconductor. In addition, its gap function possesses deep
+point minima, whose ratio of the gap anisotropy is more than 10. On the
+theoretical side, however, it is nontrivial to understand the origin of such a
+peculiar superconductivity. In the present paper, we propose a mechanism of the
+s-wave superconductivity with deep gap minima, based on the theoretical model
+where strong electron-phonon coupling as well as the moderate magnetic
+fluctuations coexist. By analyzing the strong coupling Eliashberg equation, we
+find that s-wave superconducting gap function owing to the electron-phonon
+coupling becomes highly anisotropic as the magnetic fluctuations increases. The
+set of model parameters for realizing the strong gap anisotropy in the present
+model will be appropriate for (Y,Lu)Ni$_2$B$_2$C. According to the present
+mechanism, (groups of) pair of gap minima appear at points on the Fermi surface
+which are connected by the nesting vector ${\bf Q}$, in both cases of s-wave
+superconductors and non s-wave ones. We briefly discuss other superconductors
+with highly anisotropic gap function, e.g., PrOs$_{4}$Sb$_{12}$ and
+Na$_{0.33}$CoO$_2$.",0409564v1
+2004-10-21,"Temperature Dependent Magnetic Anisotropy in (Ga,Mn)As Layers","It is demonstrated by SQUID measurements that (Ga,Mn)As films can exhibit
+perpendicular easy axis at low temperatures, even under compressive strain,
+provided that the hole concentration is sufficiently low. In such films, the
+easy axis assumes a standard in-plane orientation when the temperature is
+raised towards the Curie temperature or the hole concentration is increased by
+low temperature annealing. These findings are shown to corroborate
+quantitatively the predictions of the mean-field Zener model for ferromagnetic
+semiconductors. The in-plane anisotropy is also examined, and possible
+mechanisms accounting for its character and magnitude are discussed.",0410549v1
+2004-10-26,Momentum anisotropy of the scattering rate in cuprate superconductors,"We examine the momentum and energy dependence of the scattering rate of the
+high temperature cuprate superconductors using angle resolved photoemission
+spectroscopy. The scattering rate is of the form a + bw around the Fermi
+surface for under and optimal doping. The inelastic coefficient ""b"" is found to
+be isotropic. The elastic term, ""a"", however, is found to be highly anisotropic
+for under and optimally doped samples, with an anisotropy which correlates with
+that of the pseudogap. This is contrasted with heavily overdoped samples, which
+show an isotropic scattering rate and an absence of the pseudogap above T_c. We
+find this to be a generic property for both single and double layer compounds.",0410680v1
+2004-12-09,Antisymmetric magnetoresistance in magnetic multilayers with perpendicular anisotropy,"While magnetoresistance (MR) has generally been found to be symmetric in
+applied field in non-magnetic or magnetic metals, we have observed
+antisymmetric MR in Co/Pt multilayers. Simultaneous domain imaging and
+transport measurements show that the antisymmetric MR is due to the appearance
+of domain walls that run perpendicular to both the magnetization and the
+current, a geometry existing only in materials with perpendicular magnetic
+anisotropy. As a result, the extraordinary Hall effect (EHE) gives rise to
+circulating currents in the vicinity of the domain walls that contributes to
+the MR. The antisymmetric MR and EHE have been quantitatively accounted for by
+a theoretical model.",0412248v1
+2004-12-17,Theoretical studies of the phase transition in the anisotropic 2-D square spin lattice,"The phase transition occurring in a square 2-D spin lattice governed by an
+anisotropic Heisenberg Hamiltonian has been studied according to two recently
+proposed methods. The first one, the Dressed Cluster Method, provides excellent
+evaluations of the cohesive energy, the discontinuity of its derivative around
+the critical (isotropic) value of the anisotropy parameter confirms the
+first-order character of the phase transition. Nevertheless the method
+introduces two distinct reference functions (either N\'eel or XY) which may in
+principle force the discontinuity. The Real Space Renormalization Group with
+Effective Interactions does not reach the same numerical accuracy but it does
+not introduce a reference function and the phase transition appears
+qualitatively as due to the existence of two domains, with specific fixed
+points. The method confirms the dependence of the spin gap on the anisotropy
+parameter occurring in the Heisenberg-Ising domain.",0412464v1
+2005-01-05,Magnetic susceptibility of a CuO2 plane in the La2CuO4 system: I. RPA treatment of the Dzyaloshinskii-Moriya Interactions,"Motivated by recent experiments on undoped La2CuO4, which found pronounced
+temperature-dependent anisotropies in the low-field magnetic susceptibility, we
+have investigated a two-dimensional square lattice of S=1/2 spins that interact
+via Heisenberg exchange plus the symmetric and anti-symmetric
+Dzyaloshinskii-Moriya anisotropies. We describe the transition to a state with
+long-ranged order, and find the spin-wave excitations, with a mean-field
+theory, linear spin-wave analysis, and using Tyablikov's RPA decoupling scheme.
+We find the different components of the susceptibility within all of these
+approximations, both below and above the N'eel temperature, and obtain evidence
+of strong quantum fluctuations and spin-wave interactions in a broad
+temperature region near the transition.",0501086v1
+2005-01-06,Ground State Properties of one-dimensional Antiferromagnetic Spin-1 Chain with Single-ion Anisotropy,"In this study, we have investigated ground state properties of
+one-dimensional antiferromagnetic spin-1 chain with single-ion anisotropy at
+very low temperatures using the Transfer Matrix method. Magnetic plateaus,
+phase diagram, specific heat, susceptibility of the spin chain have been
+evaluated numerically from the free energy. Results are in good agreement with
+the experimental data for the spin-1 compounds
+[Ni$_2$(Medpt)$_2$($\mu$-ox)(H$_2$O)$_2$](ClO$_4$)$_2$2H$_2$O,
+[Ni$_{2}$(Medpt)$_{2}$($\mu$-ox)($\mu$-N$_{3}$)](ClO$_{4}$)0.5H$_{2}$O,
+Ni(C$_2$H$_8$N$_2$)Ni(CN)$_4$ and Ni(C$_{10}$H$_8$N$_2$)$_2$Ni(CN)$_4$.H$_2$O.
+However, spin-Peierls transition have not been observed in the temperature
+dependence of specific heat and magnetic susceptibility.",0501111v2
+2005-01-18,Temperature dependent anisotropy of the penetration depth and coherence length in MgB$_2,"We report measurements of the temperature dependent anisotropies
+($\gamma_\lambda$ and $\gamma_\xi$) of both the London penetration depth
+$\lambda$ and the upper critical field of MgB$_2$. Data for
+$\gamma_\lambda=\lambda_c/\lambda_a$ was obtained from measurements of
+$\lambda_{a}$ and $\lambda_c$ on a single crystal sample using a tunnel diode
+oscillator technique. $\gamma_\xi=H_{c2}^{\parallel c}/H_{c2}^{\bot c}$ was
+deduced from field dependent specific heat measurements on the same sample.
+$\gamma_\lambda$ and $\gamma_\xi$ have opposite temperature dependencies, but
+close to $T_c$ tend to a common value ($\gamma_\lambda\simeq
+\gamma_\xi=1.75\pm0.05$). These results are in good agreement with theories
+accounting for the two gap nature of MgB$_2$",0501415v2
+2005-01-24,Metamagnetic phase transition of the antiferromagnetic Heisenberg icosahedron,"The observation of hysteresis effects in single molecule magnets like
+Mn$_{12}$-acetate has initiated ideas of future applications in storage
+technology. The appearance of a hysteresis loop in such compounds is an outcome
+of their magnetic anisotropy. In this Letter we report that magnetic hysteresis
+occurs in a spin system without any anisotropy, specifically, where spins
+mounted on the vertices of an icosahedron are coupled by antiferromagnetic
+isotropic nearest-neighbor Heisenberg interaction giving rise to geometric
+frustration. At T=0 this system undergoes a first order metamagnetic phase
+transition at a critical field $\Bcrit$ between two distinct families of ground
+state configurations. The metastable phase of the system is characterized by a
+temperature and field dependent survival probability distribution.",0501558v1
+2005-02-24,Magnetic susceptibility anisotropies in a two-dimensional quantum Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions,"The magnetic and thermodynamic properties of the two-dimensional quantum
+Heisenberg antiferromagnet that incorporates both a Dzyaloshinskii-Moriya and
+pseudo-dipolar interactions are studied within the framework of a generalized
+nonlinear sigma model (NLSM). We calculate the static uniform susceptibility
+and sublattice magnetization as a function of temperature and we show that: i)
+the magnetic-response is anisotropic and differs qualitatively from the
+expected behavior of a conventional easy-axis QHAF; ii) the Neel second-order
+phase transition becomes a crossover, for a magnetic field B perpendicular to
+the CuO(2) layers. We provide a simple and clear explanation for all the
+recently reported unusual magnetic anisotropies in the low-field susceptibility
+of La(2)CuO(4), L. N. Lavrov et al., Phys. Rev. Lett. 87, 017007 (2001), and we
+demonstrate explicitly why La(2)CuO(4) can not be classified as an ordinary
+easy-axis antiferromagnet.",0502588v3
+2005-03-01,Berry phase of magnons in textured ferromagnets,"We study the energy spectrum of magnons in a ferromagnet with topologically
+nontrivial magnetization profile. In the case of inhomogeneous magnetization
+corresponding to a metastable state of ferromagnet, the spin-wave equation of
+motion acquires a gauge potential leading to a Berry phase for the magnons
+propagating along a closed contour. The effect of magnetic anisotropy is
+crucial for the Berry phase: we show that the anisotropy suppresses its
+magnitude, which makes the Berry phase observable in some cases, similar to the
+Aharonov-Bohm effect for electrons. For example, it can be observed in the
+interference of spin waves propagating in mesoscopic rings. We discuss the
+effect of domain walls on the interference in ferromagnetic rings, and propose
+some experiments with a certain geometry of magnetization. We also show that
+the nonvanishing average topological field acts on the magnons like a uniform
+magnetic field on electrons. It leads to the quantization of the magnon
+spectrum in the topological field.",0503013v1
+2005-03-07,Experimental compaction of anisotropic granular media,"We report on experiments to measure the temporal and spatial evolution of
+packing arrangements of anisotropic and weakly confined granular material,
+using high-resolution $\gamma$-ray adsorption. In these experiments, the
+particle configurations start from an initially disordered,
+low-packing-fraction state and under vertical solicitations evolve to a dense
+state. We find that the packing fraction evolution is slowed by the grain
+anisotropy but, as for spherically shaped grains, can be well fitted by a
+stretched exponential. For a given type of grains, the characteristic times of
+relaxation and of convection are found to be of the same order of magnitude. On
+the contrary compaction mechanisms in the media strongly depend on the grain
+anisotropy.",0503151v1
+2005-04-01,"Magnetoresistance Anomalies in (Ga,Mn)As Epilayers with Perpendicular Magnetic Anisotropy","We report the observation of anomalies in the longitudinal magnetoresistance
+of tensile-strained (Ga,Mn)As epilayers with perpendicular magnetic anisotropy.
+Magnetoresistance measurements carried out in the planar geometry (magnetic
+field parallel to the current density) reveal ""spikes"" that are antisymmetric
+with respect to the direction of the magnetic field. These anomalies always
+occur during magnetization reversal, as indicated by a simultaneous change in
+sign of the anomalous Hall effect. The data suggest that the antisymmetric
+anomalies originate in anomalous Hall effect contributions to the longitudinal
+resistance when domain walls are located between the voltage probes. This
+interpretation is reinforced by carrying out angular sweeps of $\vec{H}$,
+revealing an antisymmetric dependence on the helicity of the field sweep.",0504038v1
+2005-04-18,Epitaxial self-organization: from surfaces to magnetic materials,"Self-organization of magnetic materials is an emerging and active field. An
+overview of the use of self-organization for magnetic purposes is given, with a
+view to illustrate aspects that cannot be covered by lithography. A first set
+of issues concerns the quantitative study of low-dimensional magnetic phenomena
+(1D and 0D). Such effects also occur in microstructured and
+lithographically-patterned materials but cannot be studied in these because of
+the complexity of such materials. This includes magnetic ordering, magnetic
+anisotropy and superparamagnetism. A second set of issues concerns the
+possibility to directly use self-organization in devices. Two sets of examples
+are given: first, how superparamagnetism can be fought by fabricating thick
+self-organized structures, and second, what new or improved functionalities can
+be expected from self-organized magnetic systems, like the tailoring of
+magnetic anisotropy or controlled dispersion of properties.",0504424v1
+2005-05-12,Magnetic relaxation measurements of exchange biased (Pt/Co) multilayers with perpendicular anisotropy,"Magnetic relaxation measurements were carried out by magneto-optical Kerr
+effect on exchange biased (Pt/Co)5/Pt/FeMn multilayers with perpendicular
+anisotropy. In these films the coercivity and the exchange bias field vary with
+Pt spacer thickness, and have a maximum for 0.2 nm. Hysteresis loops do not
+reveal important differences between the reversal for ascending and descending
+fields. Relaxation measurements were fitted using Fatuzzo's model, which
+assumes that reversal occurs by domain nucleation and domain wall propagation.
+For 2 nm thick Pt spacer (no exchange bias) the reversal is dominated by domain
+wall propagation starting from a few nucleation centers. For 0.2 nm Pt spacer
+(maximum exchange bias) the reversal is strongly dominated by nucleation, and
+no differences between the behaviour of the ascending and descending branches
+can be observed. For 0.4 nm Pt spacer (weaker exchange bias) the nucleation
+density becomes less important, and the measurements reveal a much stronger
+density of nucleation centers in the descending branch.",0505312v1
+2005-05-26,Magnetic behavior of a spin-1 dimer: model system for homodinuclear nickel (II) complexes,"Magnetic behavior of a spin-1 Heisenberg dimer is analysed in dependence on
+both uniaxial single-ion anisotropy and XXZ exchange anisotropy in a zero- as
+well as non-zero longitudinal magnetic field. A complete set of eigenfunctions
+and eigenvalues of the total Hamiltonian is presented together with an exact
+analytical expression for the Gibbs free energy, longitudinal magnetization,
+longitudinal and transverse susceptibility. The obtained theoretical results
+are compared with the relevant experimental data of
+[Ni2(Medpt)2(ox)(H2O)2](ClO4)2.2H2O (Medpt = methyl-bis(3-aminopropyl)amine).",0505636v2
+2005-05-30,Spin Disorder and Magnetic Anisotropy in Fe3O4 Nanoparticles,"We have studied the magnetic behavior of dextran-coated magnetite
+(Fe$_3$O$_4$) nanoparticles with median particle size $\left<d\right>=8$ $nm$.
+Magnetization curves and in-field M\""ossbauer spectroscopy measurements showed
+that the magnetic moment $M_S$ of the particles was much smaller than the bulk
+material. However, we found no evidence of magnetic irreversibility or
+non-saturating behavior at high fields, usually associated to spin canting. The
+values of magnetic anisotropy $K_{eff}$ from different techniques indicate that
+surface or shape contributions are negligible. It is proposed that these
+particles have bulk-like ferrimagnetic structure with ordered A and B
+sublattices, but nearly compensated magnetic moments. The dependence of the
+blocking temperature with frequency and applied fields, $T_B(H,\omega)$,
+suggests that the observed non-monotonic behavior is governed by the strength
+of interparticle interactions.",0505682v5
+2005-06-20,Effects of trap anisotropy on impurity scattering regime in a Fermi gas,"We evaluate the low-lying oscillation modes and the ballistic expansion
+properties of a harmonically trapped gas of fermionic K40 atoms containing
+thermal Rb87 impurities as functions of the anisotropy of the trap. Numerical
+results are obtained by solving the Vlasov-Landau equations for the one-body
+phase-space distribution functions and are used to test simple scaling
+Ansatzes. Starting from the gas in a weak impurity-scattering regime inside a
+spherical trap, the time scales associated to motions in the axial and
+azimuthal directions enter into competition as the trap is deformed to an
+elongated cigar-like shape. This competition gives rise to coexistence of
+collisionless and hydrodynamic behaviors in the low-lying surface modes of the
+gas as well as to a dependence of the aspect ratio of the expanding cloud on
+the collision time.",0506496v1
+2005-07-26,55Mn NMR and magnetization studies of La0.67Sr0.33MnO3 thin films,"55Mn nuclear magnetic resonance and magnetization studies of the series of
+La0.67Sr0.33MnO3 thin films have been performed at low temperature. Two
+distinct lines were observed, at 322 MHz and 380 MHz, corresponding to two
+different phases, the former located at the interface, with localized charges,
+and the latter corresponding to the film bulk, with itinerant carriers (as it
+was also found in Ca manganite films). The spin-echo amplitude was measured as
+a function of a dc magnetic field applied either in the film plane or
+perpendicular to it. The field dependence of both the main NMR signal intensity
+and frequency shift is quite consistent with that calculated in a simple single
+domain model. The best fit to the model shows that magnetization rotation
+processes play a dominant role when the applied field exceeds the effective
+anisotropy field. Distinctly different magnetic anisotropies are deduced from
+the interface NMR signal.",0507598v1
+2005-08-09,Disordered and ordered states of exactly solvable Ising-Heisenberg planar models with a spatial anisotropy,"Ground-state and finite-temperature properties of a special class of exactly
+solvable Ising-Heisenberg planar models are examined using the generalized
+decoration-iteration and star-triangle mapping transformations. The
+investigated spin systems exhibit an interesting quantum behaviour manifested
+in a remarkable geometric spin frustration, which appears notwithstanding the
+purely ferromagnetic interactions of the considered model systems. This kind of
+spin frustration originates from an easy-plane anisotropy in the XXZ Heisenberg
+interaction between nearest-neighbouring spins that favours ferromagnetic
+ordering of their transverse components, whereas their longitudinal components
+are aligned antiferomagnetically.",0508224v2
+2005-08-11,Magnetization self-organization in a single-domain ferromagnet subject to a spin current,"The Landau-Lifshitz equation for the magnetization dynamics of a
+single-domain magnetic system is solved using the methods of self-organization.
+The description takes into account the torque due to spin transfer. The
+potential energy of the system includes the uniaxial and easy-plane
+anisotropies, and the Zeeman energy due to an external magnetic field. The
+equilibrium and stationary states are investigated as a function of the spin
+current and external magnetic field. The presented bifurcation diagram allows
+to determine the margins of a neutral stability mode of the equilibrium and
+stationary states for different values of the easy-plane anisotropy constant.
+Using the power spectral density method, the trajectory tracing, Hausdorff
+dimension, and maximum Lyapunov exponent, the dynamics of the phase states in
+an external magnetic field is demonstrated. The analytical transcendent
+equations for switching between different equilibrium states are also obtained,
+proving the importance of phase averaging.",0508280v1
+2005-09-06,Conduction anisotropy and Hall effect in the organic conductor (TMTTF)2AsF6: evidence for Luttinger liquid and charge ordering,"We present the high-temperature (70 K < T < 300 K) resistivity anisotropy and
+Hall effect measurements of the quasi-one-dimensional (1D) organic conductor
+(TMTTF)2AsF6. The temperature variations of the resistivity are pronouncedly
+different for the three different directions, with metallic-like at high
+temperatures for the a-axis only. Above 220 K the Hall coefficient R_H is
+constant, positive and strongly enhanced over the expected value; and the
+corresponding carrier concentration is almost 100 times lower than calculated
+for one hole/unit cell. Our results give evidence for the existence of a
+high-temperature regime above 200 K where the 1D Luttinger liquid features
+appear in the transport properties. Our measurements also give strong evidence
+of charge ordering in (TMTTF)2AsF6. At the charge-ordering transition T_{CO}
+\approx 100 K, R_H(T) abruptly changes its behavior, switches sign and rapidly
+increases with further temperature decrease.",0509147v1
+2005-09-15,Asymmetric magnetization reversal in the exchange bias system Fe/FeF_2 studied by MOKE,"The asymmetry of the magnetization reversal process in exchange biased
+Fe/FeF$_2$ has been studied by magneto-optical Kerr effect. Qualitatively
+different transverse magnetization loops are observed for different directions
+of the cooling and the measuring field. These loops can be simulated by a
+simple calculation of the total energy density which includes the relevant
+magnetic anisotropies and coherent magnetization rotation only. Asymmetric
+magnetization reversal is shown to originate from the unidirectional anisotropy
+and may be observed if the external measuring field is not collinear with
+either the exchange bias or the easy axis of the antiferromagnetic epitaxial
+FeF$_2$(110) layer.",0509419v2
+2005-09-19,Observation of field-dependent magnetic parameters in the magnetic molecule {Ni4Mo12},"We investigate the bulk magnetic, electron paramagnetic resonance, and
+magneto-optical properties of {Ni4Mo12}, a magnetic molecule with
+antiferromagnetically coupled tetrahedral {Ni4Mo12} in a diamagnetic molybdenum
+matrix. The low-temperature magnetization exhibits steps at irregular field
+intervals, a result that cannot be explained using a Heisenberg model even if
+it is augmented by magnetic anisotropy and biquadratic terms. Allowing the
+exchange and anisotropy parameters to depend on the magnetic field provides the
+best fit to our data, suggesting that the molecular structure (and thus the
+interactions between spins) may be changing with applied magnetic field.",0509476v2
+2005-09-21,Tunneling magnetoresistance in devices based on epitaxial NiMnSb with uniaxial anisotropy,"We demonstrate tunnel magnetoresistance (TMR) junctions based on a tri layer
+system consisting of an epitaxial NiMnSb, aluminum oxide and CoFe tri layer.
+The junctions show a tunnelling magnetoresistance of Delta R/R of 8.7% at room
+temperature which increases to 14.7% at 4.2K. The layers show clear separate
+switching and a small ferromagnetic coupling. A uniaxial in plane anisotropy in
+the NiMnSb layer leads to different switching characteristics depending on the
+direction in which the magnetic field is applied, an effect which can be used
+for sensor applications.",0509538v1
+2005-09-29,"Modification of intergrain connectivity, upper critical field anisotropy, and critical current density in ion irradiated MgB2 films","We study the effect of 100 MeV Silicon and 200 MeV Gold ion irradiation on
+the inter and intra grain properties of superconducting thin films of Magnesium
+Diboride. Substantial decrease in inter-grain connectivity is observed,
+depending on irradiation dose and type of ions used. We establish that
+modification of sigma band scattering mechanism, and consequently the upper
+critical field and anisotropy, depends on the size and directional properties
+of the extrinsic defects. Post heavy ion irradiation, the upper critical field
+shows enhancement at a defect density that is five orders of magnitude less
+compared to neutron irradiation. The critical current density however is best
+improved through light ion irradiation.",0509755v1
+2005-10-13,Random field spin models beyond one loop: a mechanism for decreasing the lower critical dimension,"The functional RG for the random field and random anisotropy O(N)
+sigma-models is studied to two loop. The ferromagnetic/disordered (F/D)
+transition fixed point is found to next order in d=4+epsilon for N > N_c
+(N_c=2.8347408 for random field, N_c=9.44121 for random anisotropy). For N <
+N_c the lower critical dimension plunges below d=4: we find two fixed points,
+one describing the quasi-ordered phase, the other is novel and describes the
+F/D transition. The lower critical dimension can be obtained in an
+(N_c-N)-expansion. The theory is also analyzed at large N and a glassy regime
+is found.",0510344v3
+2005-10-16,Spiral Spin Order and Transport Anisotropy in Underdoped Cuprates,"We discuss the spiral spin density wave model and its application to explain
+properties of underdoped La$_{2-x}$Sr$_x$CuO$_4$. We argue that the spiral
+picture is theoretically well justified in the context of the extended $t-J$
+model, and then show that it can explain a number of observed features, such as
+the location and symmetry of the incommensurate peaks in elastic neutron
+scattering, as well as the in-plane resistivity anisotropy. A consistent
+description of the low doping region (below 10% or so) emerges from the spiral
+formulation, in which the holes show no tendency towards any type of charge
+order and the physics is purely spin driven.",0510416v1
+2005-10-24,Reduction of threshold current density for current-driven domain wall motion by shape control,"We investigated the aspect ratio (thickness/width) dependence of the
+threshold current density required for the current-driven domain wall (DW)
+motion for the Ni81Fe19 nanowires. It has been shown theoretically that the
+threshold current density is proportional to the product of the hard-axis
+magnetic anisotropy Kperp and the DW width lamda. (Phys. Rev. Lett. 92, 086601
+(2004).) We show experimentally that Kperp can be controlled by the magnetic
+shape anisotropy in the case of the Ni81Fe19 nanowires, and that the threshold
+current density increases with an increase of Kperp*l. We succeeded to reduce
+the threshold current density by half by the shape control.",0510619v2
+2005-10-31,Generalized Mittag-Leffler functions in the theory of finite-size scaling for systems with strong anisotropy and/or long-range interaction,"The difficulties arising in the investigation of finite-size scaling in
+$d$--dimensional O(n) systems with strong anisotropy and/or long-range
+interaction, decaying with the interparticle distance $r$ as $r^{-d-\sigma}$
+($0<\sigma\leq2$), are discussed. Some integral representations aiming at the
+simplification of the investigations are presented for the classical and
+quantum lattice sums that take place in the theory. Special attention is paid
+to a more general form allowing to treat both cases on an equal footing and in
+addition cases with strong anisotropic interactions and different geometries.
+The analysis is simplified further by expressing this general form in terms of
+a generalization of the Mittag-Leffler special functions. This turned out to be
+very useful for the extraction of asymptotic finite-size behaviours of the
+thermodynamic functions.",0510834v2
+2005-11-11,"The open XXZ-chain: Bosonisation, Bethe ansatz and logarithmic corrections","We calculate the bulk and boundary parts of the free energy for an open
+spin-1/2 XXZ-chain in the critical regime by bosonisation. We identify the
+cutoff independent contributions and determine their amplitudes by comparing
+with Bethe ansatz calculations at zero temperature T. For the bulk part of the
+free energy we find agreement with Lukyanov's result [Nucl.Phys.B 522, 533
+(1998)]. In the boundary part we obtain a cutoff independent term which is
+linear in T and determines the temperature dependence of the boundary
+susceptibility in the attractive regime for $T\ll 1$. We further show that at
+particular anisotropies where contributions from irrelevant operators with
+different scaling dimensions cross, logarithmic corrections appear. We give
+explicit formulas for these terms at those anisotropies where they are most
+important. We verify our results by comparing with extensive numerical
+calculations based on a numerical solution of the T=0 Bethe ansatz equations,
+the finite temperature Bethe ansatz equations in the quantum-transfer matrix
+formalism, and the density-matrix renormalisation group applied to transfer
+matrices.",0511272v1
+2005-11-11,"Spin amplification, reading, and writing in transport through anisotropic magnetic molecules","Inelastic transport through a single magnetic molecule weakly coupled to
+metallic leads is studied theoretically. We consider dynamical processes that
+are relevant for writing, storing, and reading spin information in molecular
+memory devices. Magnetic anisotropy is found to be crucial for slow spin
+relaxation. In the presence of anisotropy we find giant spin amplification: The
+spin accumulated in the leads if a bias voltage is applied to a molecule
+prepared in a spin-polarized state can be made exponentially large in a
+characteristic energy divided by temperature. For one ferromagnetic and one
+paramagnetic lead the molecular spin can be reversed by applying a bias voltage
+even in the absence of a magnetic field. We propose schemes for reading and
+writing spin information based on our findings.",0511291v2
+2005-11-15,Magnetism in reduced dimensions,"We propose a short overview of a few selected issues of magnetism in reduced
+dimensions, which are the most relevant to set the background for more
+specialized contributions to the present Special Issue. Magnetic anisotropy in
+reduced dimensions is discussed, on a theoretical basis, then with experimental
+reports and views from surface to single-atom anisotropy. Then conventional
+magnetization states are reviewed, including macrospins, single domains,
+multidomains, and domain walls in stripes. Dipolar coupling is examined for
+lateral interactions in arrays, and for interlayer interactions in films and
+dots. Finally thermally-assisted magnetization reversal and superparamagnetism
+are presented. For each topic we sought a balance between well established
+knowledge and recent developments.",0511362v1
+2005-11-15,Measuring the Penetration Depth Anisotropy in MgB$_2$ using Small-Angle Neutron Scattering,"Using small-angle neutron scattering we have measured the misalignment
+between an applied field of 4 kOe and the flux-line lattice in MgB$_2$, as the
+field is rotated away from the c axis by an angle $\theta$. The measurements,
+performed at 4.9 K, showed the vortices canting towards the c axis for all
+field orientations. Using a two-band/two-gap model to calculate the
+magnetization we are able to fit our results yielding a penetration depth
+anisotropy, $\glam = 1.1 \pm 0.1$.",0511376v3
+2005-12-22,Entanglement Entropy dynamics in Heisenberg chains,"By means of the time-dependent density matrix renormalization group algorithm
+we study the zero-temperature dynamics of the Von Neumann entropy of a block of
+spins in a Heisenberg chain after a sudden quench in the anisotropy parameter.
+In the absence of any disorder the block entropy increases linearly with time
+and then saturates. We analyze the velocity of propagation of the entanglement
+as a function of the initial and final anisotropies and compare, wherever
+possible, our results with those obtained by means of Conformal Field Theory.
+In the disordered case we find a slower (logarithmic) evolution which may
+signals the onset of entanglement localization.",0512586v2
+2006-01-04,Pressure-Induced Zero-Gap Semiconducting State in Organic Conductor $α$-(BEDT-TTF)$_2$I$_3$ Salt,"We show a zero-gap semiconducting (ZGS) state in the quasi-two-dimensional
+organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$ salt, which emerges under
+uniaxial pressure along the a-axis (the stacking axis of the BEDT-TTF
+molecule). The ZGS state is the state in which a Dirac cone with the band
+spectrum of a linear dispersion exists around the Fermi point connecting an
+unoccupied (electron) band with an occupied (hole) band. The spectrum exhibits
+a large anisotropy in velocity, which depends on the direction from the Fermi
+point. By varying the magnitude of several transfer energies of a tight-binding
+model with four sites per unit cell, it is shown that the ZGS state exists in a
+wide pressure range, and is attributable to the large anisotropy of the
+transfer energies along the stacking axis.",0601068v3
+2006-01-10,Linear polarization of the photoluminescence of quantum wells,"The degree and orientation of the magnetic-field induced linear polarization
+of the photoluminescence from a wide range of heterostructures containing
+(Cd,Mn)Te quantum wells between (Cd,Mn,Mg)Te barriers has been studied as a
+function of detection photon energy, applied magnetic field strength and
+orientation in the quantum well plane. A theoretical description of this effect
+in terms of an in-plane deformation acting on the valence band states is
+presented and is verified by comparison with the experimental data. We
+attempted to identify clues to the microscopic origin of the valence band spin
+anisotropy and to the mechanisms which actually determine the linear
+polarization of the PL in the quantum wells subject to the in-plane magnetic
+field. The conclusions of the present paper apply in full measure to
+non-magnetic QWs as well as ensembles of disk-like QDs with shape and/or strain
+anisotropy.",0601204v1
+2006-01-12,Observation of Spin Relaxation Anisotropy in Semiconductor Quantum Wells,"Spin relaxation of two-dimensional electrons in asymmetrical (001) AlGaAs
+quantum wells are measured by means of Hanle effect. Three different spin
+relaxation times for spins oriented along [110], [1-10] and [001]
+crystallographic directions are extracted demonstrating anisotropy of
+D'yakonov-Perel' spin relaxation mechanism. The relative strengths of Rashba
+and Dresselhaus terms describing the spin-orbit coupling in semiconductor
+quantum well structures. It is shown that the Rashba spin-orbit splitting is
+about four times stronger than the Dresselhaus splitting in the studied
+structure.",0601252v1
+2006-01-18,Magnetic domain structure and dynamics in interacting ferromagnetic stacks with perpendicular anisotropy,"The time and field dependence of the magnetic domain structure at
+magnetization reversal were investigated by Kerr microscopy in interacting
+ferromagnetic Co/Pt multilayers with perpendicular anisotropy. Large local
+inhomogeneous magnetostatic fields favor mirroring domain structures and domain
+decoration by rings of opposite magnetization. The long range nature of these
+magnetostatic interactions gives rise to ultra-slow dynamics even in zero
+applied field, i.e. it affects the long time domain stability. Due to this
+additionnal interaction field, the magnetization reversal under short magnetic
+field pulses differs markedly from the well-known slow dynamic behavior.
+Namely, in high field, the magnetization of the coupled harder layer has been
+observed to reverse more rapidly by domain wall motion than the softer layer
+alone.",0601401v1
+2006-01-26,The high temperature expansion of the classical $XYZ$ chain,"We present the $\beta$-expansion of the Helmholtz free energy of the
+classical $XYZ$ model, with a single-ion anisotropy term and in the presence of
+an external magnetic field, up to order $\beta^{12}$. We compare our results to
+the numerical solution of Joyce's [Phys. Rev. Lett. 19, 581 (1967)] expression
+for the thermodynamics of the $XXZ$ classical model, with neither single-ion
+anisotropy term nor external magnetic field. This comparison shows that the
+derived analytical expansion is valid for intermediate temperatures such as
+$kT/J_x \approx 0.5$. We show that the specific heat and magnetic
+susceptibility of the spin-2 antiferromagnetic chain can be approximated by
+their respective classical results, up to $kT/J \approx 0.8$, within an error
+of 2.5%. In the absence of an external magnetic field, the ferromagnetic and
+antiferromagnetic chains have the same classical Helmholtz free energy. We show
+how this two types of media react to the presence of an external magnetic
+field.",0601615v1
+2006-02-26,Strong temperature dependence of antiferromagnetic coupling in CoFeB/Ru/CoFeB,"The temperature dependence of saturation and spin-flop fields for artificial
+ferrimagnets (AFi) based on antiparallel coupled CoFeB/Ru/CoFeB trilayers has
+been investigated in a temperature range between 80K and 600K. The results
+presented in this paper are relevant for magnetic devices using this system,
+e.g. magnetic-random access memory based on spin-flop switching. In good
+accordance to the theory, the saturation field Hsat behaves like Hsat ~ H_0
+(T/T_0)/sinh(T/T_0) with a characteristic temperature of T_0 = 150K. Within
+this model, the Fermi velocity for the Ru layer is of the order of 10^5m/s,
+therefore, explaining the strong variation of the coupling strength with the
+temperature in Ru based AFi. Furthermore, a strong uniaxial anisotropy of K_u =
+2x10^3 J/m^3 with a small angular distribution of the anisotropy axes is
+observed for the AFi trilayers based on amorphous CoFeB alloys.",0602609v2
+2006-04-05,Interparticle interaction and size effect in polymer coated magnetite nanoparticles,"Magnetization and Mossbauer studies have been performed on the polymer coated
+magnetite nanoparticles with particle size from 5.1 to 14.7 nm. The maximum in
+the temperature dependence of magnetization (TM) is found to be inconsistent
+with the particle size (DTEM). The effective magnetic anisotropy (Kan) is found
+to increase with the decrease of DTEM, which is attributed to the increase of
+surface anisotropy. The absence of coercivity and remanence of magnetization
+noticed well above TM indicates the superparamagnetic behaviour, which has also
+been observed in the temperature dependent Mossbauer results. The temperature
+dependence of hyperfine field is found to follow similar dependence of
+saturation magnetization for bulk magnetite.",0604119v2
+2006-04-13,Charged inclusion in nematic liquid crystals,"We present a general theory of liquid crystals under inhomogeneous electric
+field in a Ginzburg-Landau scheme. The molecular orientation can be deformed by
+electric field when the dielectric tensor is orientation-dependent. We then
+investigate the influence of a charged particle on the orientation order in a
+nematic state. The director is aligned either along or perpendicular to the
+local electric field around the charge, depending on the sign of the dielectric
+anisotropy. The deformation becomes stronger with increasing the ratio $Ze/R$,
+where $Ze$ is the charge and $R$ is the radius of the particle. Numerical
+analysis shows the presence of defects around the particle for large $Ze/R$.
+They are nanometer-scale defects for microscopic ions. If the dielectric
+anisotropy is positive, a Saturn ring defect appears. If it is negative, a pair
+of point defects appear apart from the particle surface, each being connected
+to the surface by a disclination line segment.",0604334v1
+2006-04-13,Signature of Fermi surface anisotropy in point contact conductance in the presence of defects,"In a previous paper (Avotina et al.,Phys. Rev. B Vol.71, 115430 (2005)) we
+have shown that in principle it is possible to image the defect positions below
+a metal surface by means of a scanning tunnelling microscope. The principle
+relies on the interference of electron waves scattered on the defects, which
+give rise to small but measurable conductance fluctuations. Whereas in that
+work the band structure was assumed to be free-electron like, here we
+investigate the effects of Fermi surface anisotropy. We demonstrate that the
+amplitude and period of the conductance oscillations are determined by the
+local geometry of the Fermi surface. The signal results from those points for
+which the electron velocity is directed along the vector connecting the point
+contact to the defect. For a general Fermi surface geometry the position of the
+maximum amplitude of the conductance oscillations is not found for the tip
+directly above the defect. We have determined optimal conditions for
+determination of defect positions in metals with closed and open Fermi
+surfaces.",0604344v1
+2006-04-17,Angular Dependent Torque Measurements on CeCoIn$_5$ Single Crystals,"Angular dependent torque measurements were performed on single crystals of
+CeCoIn$_5$, a heavy fermion superconductor ($T_{c0}$ = 2.3 K), in the
+temperature, $T$, range 1.9 K $\leq T \leq $ 20 K and magnetic fields $H$ up to
+14 T. A large paramagnetic effect is found in the normal state. Torque
+measurements in the mixed state were also performed. The torque curves show
+sharp hysteresis peaks at $\theta = 90^{o}$ ($\theta$ is the angle between $H$
+and the $c-$axis of the crystal), a result of intrinsic pinning of vortices.
+The anisotropy $\gamma \equiv \sqrt{m_{c}/m_{a}}$ in the mixed state was
+determined from the reversible part of the vortex contribution to the torque
+signal using Kogan's model [Phys. Rev. B \textbf{38}, 7049 (1988)]. The
+anisotropy $\gamma$ decreases with increasing magnetic field and temperature.
+The fact that $\gamma$ is not a constant points towards a multiband scenario in
+this heavy fermion material.",0604399v1
+2006-04-18,The gap exponent of XXZ model in a transverse field,"We have calculated numerically the gap exponent of the anisotropic Heisenberg
+model in the presence of the transverse magnetic field. We have implemented the
+modified Lanczos method to obtain the excited states of our model with the same
+accuracy of the ground state. The coefficient of the leading term in the
+perturbation expansion diverges in the thermodynamic limit (N --> infinity). We
+have obtained the relation between this divergence and the scaling behaviour of
+the energy gap. We have found that the opening of gap in the presence of
+transverse field scales with a critical exponent which depends on the
+anisotropy parameter (Delta). Our numerical results are in well agreement with
+the field theoretical approach in the whole range of the anisotropy parameter,
+-1 < Delta < 1.",0604405v1
+2006-05-08,Mott glass in site-diluted S=1 antiferromagnets with single-ion anisotropy,"The interplay between site dilution and quantum fluctuations in S=1
+Heisenberg antiferromagnets on the square lattice is investigated using quantum
+Monte Carlo simulations. Quantum fluctuations are tuned by a single-ion
+anisotropy D. In the clean limit, a sufficiently large D>D_c = 5.65(2) J forces
+each spin into its m_S=0 state, and thus destabilizes antiferromagnetic order.
+In the presence of site dilution, quantum fluctuations are found to destroy
+N\'eel order before the percolation threshold of the lattice is reached, if D
+exceeds a critical value D^* = 2.3(2) J. This mechanism opens up an extended
+quantum-disordered Mott glass phase on the percolated lattice, characterized by
+a gapless spectrum and vanishing uniform susceptibility.",0605200v1
+2006-05-09,Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets,"Motivated by the recent discovery of a low temperature spin liquid phase in
+layered organic compound $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$ which becomes a
+superconductor under pressure, we examine the phase transition of Mott
+insulating and superconducting (SC) states in a Hubbard-Heisenberg model on an
+anisotropic triangular lattice. We use a renormalized mean field theory to
+study the Gutzwiller projected BCS wavefucntions. The half filled electron
+system is a Mott insulator at large on-site repulsion $U$, and is a
+superconductor at a moderate $U$. The symmetry of the SC state depends on the
+anisotropy, and is gapful with $d_{x^2-y^2}+id_{xy}$ symmetry near the
+isotropic limit and is gapless with $d_{x^2-y^2}$ symmetry at small anisotropy
+ratio.",0605214v1
+2006-05-10,Random anisotropy disorder in superfluid 3He-A in aerogel,"The anisotropic superfluid 3He-A in aerogel provides an interesting example
+of a system with continuous symmetry in the presence of random anisotropy
+disorder. Recent NMR experiments allow us to discuss two regimes of the
+orientational disorder, which have different NMR properties. One of them, the
+(s)-state, is identified as the pure Larkin-Imry-Ma state. The structure of
+another state, the (f)-state, is not very clear: probably it is the
+Larkin-Imry-Ma state contaminated by the network of the topological defects
+pinned by aerogel.",0605276v8
+2006-06-01,"Aluminium and carbon doped MgB2: band filling, band shift, and anisotropy loss","In this work the effect of Carbon and Aluminium doping on the multiband MgB2
+superconductor is analyzed. Using the rigid band and virtual crystal
+approximations (RBA and VCA), it was found that the main effect of doping on
+the band structure is band filling and a relative band-shift. If this
+band-shift is eliminated with an appropriate change of scale, then the RBA
+provides a good description of the band structure as function of doping. With
+this procedure both the inplane electrical conductivity of the C- and Al-doped
+MgB2 and the superconducting critical temperature follow the same curve. The Tc
+graph approximately follows the sigma-band density of states; the differences
+between these two can be explained by loss of anisotropy which plays an
+important role in these systems.",0606019v1
+2006-06-03,Non-linear response of single-molecule magnets: field-tuned quantum-to-classical crossovers,"Quantum nanomagnets can show a field dependence of the relaxation time very
+different from their classical counterparts, due to resonant tunneling via
+excited states (near the anisotropy barrier top). The relaxation time then
+shows minima at the resonant fields H_{n}=n D at which the levels at both sides
+of the barrier become degenerate (D is the anisotropy constant). We showed that
+in Mn12, near zero field, this yields a contribution to the nonlinear
+susceptibility that makes it qualitatively different from the classical curves
+[Phys. Rev. B 72, 224433 (2005)]. Here we extend the experimental study to
+finite dc fields showing how the bias can trigger the system to display those
+quantum nonlinear responses, near the resonant fields, while recovering an
+classical-like behaviour for fields between them. The analysis of the
+experiments is done with heuristic expressions derived from simple balance
+equations and calculations with a Pauli-type quantum master equation.",0606091v1
+2006-06-05,In-plane anisotropy of the electronic structure for the charge/orbital-ordered state in half-doped manganite with layered structure,"We report on the in-plane anisotropy of the electronic response in the
+spin/charge/orbital ordered phase of a half-doped layered-structure manganite.
+The optical conductivity spectra for a single domain of Eu$_{1/2}$%
+Ca$_{3/2}$MnO$_{4}$ unambiguously show the anisotropic charge dynamics which
+well corresponds to the theoretical calculation: the optical conductivity with
+the polarization along the zigzag ferromagnetic chain direction exhibits a
+smaller gap and a larger intensity at lower energies than that of the
+perpendicular polarization mostly due to the charge/orbital ordering and the
+associated quantum interference effect.",0606094v1
+2006-06-19,Spin Diffusion in Trapped Gases: Anisotropy in Dipole and Quadrupole Modes,"Recent experiments in a mixture of two hyperfine states of trapped Bose gases
+show behavior analogous to a spin-1/2 system, including transverse spin waves
+and other familiar Leggett-Rice-type effects. We have derived the kinetic
+equations applicable to these systems, including the spin dependence of
+interparticle interactions in the collision integral, and have solved for
+spin-wave frequencies and longitudinal and transverse diffusion constants in
+the Boltzmann limit. We find that, while the transverse and longitudinal
+collision times for trapped Fermi gases are identical, the Bose gas shows
+unusual diffusion anisotropy in both dipole and quadrupole modes. Moreover, the
+lack of spin isotropy in the interactions leads to the non-conservation of
+transverse spin, which in turn has novel effects on the hydrodynamic modes.",0606490v1
+2006-06-23,Dynamical spin chirality and spin anisotropy in gapped S=1/2 quantum systems,"We have studied the spin anisotropy in spin-singlet ground state compounds
+and the magnetic chirality, as measured by inelastic polarized neutron
+scattering techniques, in the chain-sublattice of Sr14Cu24O41. In-plane and out
+of plane magnetic fluctuations are measured to be anisotropic and further
+discussed in the light of the current hypothesis of spin-orbit coupling. We
+show that under appropriate conditions of magnetic field and neutron
+polarization, the \textit{trivial} magnetic chirality selects only one of the
+Zeeman splitted triplet states for scattering and erases the other one that
+posses opposite helicity. Our analysis pertains to previous studies on
+dynamical magnetic chirality and chiral critical exponents, where the ground
+state is chiral itself, the so-called \textit{non-trivial} dynamical magnetic
+chirality. As it turns out, both \textit{trivial} and \textit{non-trivial}
+dynamical magnetic chirality have identical selection rules for inelastic
+polarized neutron scattering experiments and it is not at all evident that they
+can be distinguished in a paramagnetic compound.",0606598v1
+2006-06-26,Flux-flow resistivity anisotropy in the instability regime in the a-b plane of epitaxial YBCO thin films,"Measurements of the nonlinear flux-flow resistivity $\rho$ and the critical
+vortex velocity $\rm v^*_\phi$ at high voltage bias close to the instability
+regime predicted by Larkin and Ovchinnikov \cite{LO} are reported along the
+node and antinode directions of the d-wave order parameter in the \textit{a-b}
+plane of epitaxial $YBa_2Cu_3O_{7-\delta}$ films. In this pinning-free regime,
+$\rho$ and $\rm v^*_\phi$ are found to be anisotropic with values in the node
+direction larger on average by 10% than in the antinode direction. The
+anisotropy of $\rho$ is almost independent of temperature and field. We
+attribute the observed results to the anisotropic quasiparticle distribution on
+the Fermi surface of $YBa_2Cu_3O_{7-\delta}$.",0606667v1
+2006-06-27,Two-loop Functional Renormalization Group of the Random Field and Random Anisotropy O(N) Models,"We study by the perturbative Functional Renormalization Group (FRG) the
+Random Field and Random Anisotropy O(N) models near $d=4$, the lower critical
+dimension of ferromagnetism. The long-distance physics is controlled by
+zero-temperature fixed points at which the renormalized effective action is
+nonanalytic. We obtain the beta functions at 2-loop order, showing that despite
+the nonanalytic character of the renormalized effective action, the theory is
+perturbatively renormalizable at this order. The physical results obtained at
+2-loop level, most notably concerning the breakdown of dimensional reduction at
+the critical point and the stability of quasi-long range order in $d<4$, are
+shown to fit into the picture predicted by our recent non-perturbative FRG
+approach.",0606698v3
+2006-06-28,Bounds on the shear load of cohesionless granular matter,"We characterize the force state of shear-loaded granular matter by relating
+the macroscopic stress to statistical properties of the force network. The
+purely repulsive nature of the interaction between grains naturally provides an
+upper bound for the sustainable shear stress, which we analyze using an
+optimization procedure inspired by the so-called force network ensemble. We
+establish a relation between the maximum possible shear resistance and the
+friction coefficient between individual grains, and find that anisotropies of
+the contact network (or the fabric tensor) only have a subdominant effect.
+These results can be considered the hyperstatic limit of the force network
+ensemble and we discuss possible implications for real systems. Finally, we
+argue how force anisotropies can be related quantitatively to experimental
+measurements of the effective elastic constants.",0606747v2
+2006-07-10,Auxetic properties and anisotropy of elastic material constants of 2D crystalline media,"Anisotropies of Young's modulus E, the shear modulus G, and Poisson's ratio
+of all 2D symmetry systems are studied. Simple necessary and sufficient
+conditions on their elastic compliances are derived to identify if any of these
+crystals are completely auxetic, non-auxetic and auxetic. Particular attention
+is paid to 2D crystals of quadratic symmetry. All mechanically stable quadratic
+crystals are characterized by three parameters belonging to a prism with the
+stability triangle in the base. Regions in the stability triangle in which
+quadratic materials are completely auxetic, non-auxetic, and auxetic are
+established. Examples of all types of auxetic properties of crystals of oblique
+and rectangular symmetry are presented.",0607230v2
+2006-07-11,Epitaxial growth of binary alloy nanostructures,"Stochastic growth of binary alloys on a weakly interacting substrate is
+studied by kinetic Monte Carlo simulation. The underlying lattice model relates
+to fcc alloys, and the kinetics are based on deposition, atomic migration with
+bond-breaking processes and exchange processes mediated by nearest neighbor
+hopping steps. We investigate the interrelation between surface processes and
+the emerging nonequilibrium structure at and below the growing surface under
+conditions where atoms in the bulk can be regarded as immobile. The parameters
+of the model are adapted to CoPt_3 alloys. Growing nanoclusters exhibit an
+anisotropic short range order, primarily caused by Pt segregation at the
+surface. The overall structural anisotropy depends on both Pt surface
+segregation and cluster shape, and can explain the perpendicular magnetic
+anisotropy (PMA) recently measured in CoPt_3 nanoclusters on a van der Waals
+substrate. The onset of L1_2 ordering in the cluster is induced by surface
+processes. The same kinetic model is applied also to continuous thin films,
+which in addition can exhibit a small bulk contribution to PMA.",0607284v1
+2006-07-14,Anisotropic Zeeman splitting in ballistic one-dimensional hole systems,"We have studied the effect of an in-plane magnetic field B on a
+one-dimensional hole system in the ballistic regime created by surface gate
+confinement. We observed clearly the lifting of the spin degeneracy due to the
+Zeeman effect on the one dimensional subbands for B applied parallel to the
+channel. In contrast, no Zeeman splitting is detected for B applied
+perpendicular to the channel, revealing an extreme anisotropy of the effective
+Lande g-factor g*. We demonstrate that this anisotropy is a direct consequence
+of the one-dimensional confinement on a system with strong spin-orbit coupling.",0607357v1
+2006-07-17,Optical Anisotropy and Pinning of the Linear Polarization of Light in Semiconductor Microcavities,"We report a strong experimental evidence of the optical anisotropy in a
+CdTe-based microcavity: the polarization of light is pinned to one of the
+crystallographic axes independently on the polarization of the excitation. The
+polarization degree depends strongly on the excitation power, reaching almost
+100 % in the stimulated regime. The relaxation time of the polarization is
+about 1 ns. We argue that all this is an effect of a splitting of the polariton
+doublet at k=0. We consider different sources for the splitting and conclude
+that the most likely one is optical birefringence in the mirrors and/or the
+cavity.",0607420v1
+2006-07-26,"Angle-dependent magnetotransport in cubic and tetragonal ferromagnets: Application to (001)- and (113)A-oriented (Ga,Mn)As","General expressions for the longitudinal and transverse resistivities of
+single-crystalline cubic and tetragonal ferromagnets are derived from a series
+expansion of the resistivity tensor with respect to the magnetization
+orientation. They are applied to strained (Ga,Mn)As films, grown on (001)- and
+(113)A-oriented GaAs substrates, where the resistivities are theoretically and
+experimentally studied for magnetic fields rotated within various planes
+parallel and perpendicular to the sample surface. We are able to model the
+measured angular dependences of the resistivities within the framework of a
+single ferromagnetic domain, calculating the field-dependent orientation of the
+magnetization by numerically minimizing the free-enthalpy density.
+Angle-dependent magnetotransport measurements are shown to be a powerful tool
+for probing both anisotropic magnetoresistance and magnetic anisotropy. The
+anisotropy parameters of the (Ga,Mn)As films inferred from the magnetotransport
+measurements agree with those obtained by ferromagnetic resonance measurements
+within a factor of two.",0607679v1
+2006-08-10,Spin excitations in the antiferromagnet NaNiO2,"In NaNiO2, Ni3+ ions form a quasi two dimensional triangular lattice of S =
+1=2 spins. The magnetic order observed below 20K has been described as an A
+type antiferromagnet with ferro- magnetic layers weakly coupled
+antiferromagnetically. We studied the magnetic excitations with the electron
+spin resonance for frequencies 1-20 cm-1, in magnetic fields up to 14 T. The
+bulk of the results are interpreted in terms of a phenomenological model
+involving bi-axial anisotropy for the spins: a strong easy-plane term, and a
+weaker anisotropy within the plane. The direction of the easy plane is
+constrained by the collective Jahn-Teller distortion occurring in this material
+at 480 K.",0608238v1
+2006-08-14,Thermal relaxation of magnetic clusters in amorphous Hf_{57}Fe_{43} alloy,"The magnetization processes in binary magnetic/nonmagnetic amorphous alloy
+Hf_{57}Fe_{43} are investigated by the detailed measurements of magnetic
+hysteresis loops, temperature dependence of magnetization, relaxation of
+magnetization and magnetic ac susceptibility, including a nonlinear term.
+Blocking of magnetic moments at lower temperatures is accompanied with the slow
+relaxation of magnetization and magnetic hysteresis loops. All of the observed
+properties are explained with the superparamagnetic behaviour of the single
+domain magnetic clusters inside the nonmagnetic host, their blocking by the
+anisotropy barriers and thermal fluctuation over the barriers accompanied by
+relaxation of magnetization. From magnetic viscosity analysis based on thermal
+relaxation over the anisotropy barriers it is found out that magnetic clusters
+occupy the characteristic volume from 25 up to 200 nm3 . The validity of the
+superparamagnetic model of Hf_{57}Fe_{43} is based on the concentration of iron
+in the Hf_{100-x}Fe_{43} system that is just below the threshold for the long
+range magnetic ordering. This work throws more light on magnetic behaviour of
+other amorphous alloys, too.",0608307v3
+2006-08-30,Electrical conductivity of cellular Si/SiC ceramic composites prepared from plant precursors,"Electrical conductivity (sigma_dc) of the cellular Si/SiC ceramic composites
+has been measured over a temperature range 25-1073 K while the thermoelectric
+power (S) has been measured over 25-300 K. Remarkably, these cellular compounds
+developed through biomimetic route - where the ceramic system grows within a
+plant bio-template retaining the structural intricacies of the native templates
+- are found to exhibit excellent mechanical, thermal, and electrical properties
+quite comparable to or even better than those of the systems prepared through
+conventional ceramic route. The electrical conductivity measured parallel
+(sigma||) and perpendicular (sigma+) to the growth axes of the native plants,
+depicts nearly temperature-independent anisotropy (sigma+/sigma||) of the order
+\~2 while the thermoelectric power is nearly isotropic. The charge conduction
+across the entire temperature range is found to follow closely the variable
+range hopping (VRH) mechanism. The conductivity anisotropy appears to be driven
+primarily by the unique microcellular morphology of the bio-templates which can
+be exploited in many electrical applications.",0608668v1
+2006-09-16,Insights into the Second Law of Thermodynamics from Anisotropic Gas-Surface Interactions,"Thermodynamic implications of anisotropic gas-surface interactions in a
+closed molecular flow cavity are examined. Anisotropy at the microscopic scale,
+such as might be caused by reduced-dimensionality surfaces, is shown to lead to
+reversibility at the macroscopic scale. The possibility of a self-sustaining
+nonequilibrium stationary state induced by surface anisotropy is demonstrated
+that simultaneously satisfies flux balance, conservation of momentum, and
+conservation of energy. Conversely, it is also shown that the second law of
+thermodynamics prohibits anisotropic gas-surface interactions in ""equilibrium"",
+even for reduced dimensionality surfaces. This is particularly startling
+because reduced dimensionality surfaces are known to exhibit a plethora of
+anisotropic properties. That gas-surface interactions would be excluded from
+these anisotropic properties is completely counterintuitive from a causality
+perspective. These results provide intriguing insights into the second law of
+thermodynamics and its relation to gas-surface interaction physics.",0609398v1
+2006-09-19,Lowest Landau-level description of a Bose-Einstein condensate in a rapidly rotating anisotropic trap,"A rapidly rotating Bose-Einstein condensate in a symmetric two-dimensional
+trap can be described with the lowest Landau-level set of states. In this case,
+the condensate wave function psi(x,y) is a Gaussian function of r^2 = x^2 +
+y^2, multiplied by an analytic function P(z) of the single complex variable z=
+x+ i y; the zeros of P(z) denote the positions of the vortices. Here, a similar
+description is used for a rapidly rotating anisotropic two-dimensional trap
+with arbitrary anisotropy (omega_x/omega_y le 1). The corresponding condensate
+wave function psi(x,y) has the form of a complex anisotropic Gaussian with a
+phase proportional to xy, multiplied by an analytic function P(zeta), where
+zeta is proportional to x + i beta_- y and 0 le beta_- le 1 is a real parameter
+that depends on the trap anisotropy and the rotation frequency. The zeros of
+P(zeta) again fix the locations of the vortices. Within the set of lowest
+Landau-level states at zero temperature, an anisotropic parabolic density
+profile provides an absolute minimum for the energy, with the vortex density
+decreasing slowly and anisotropically away from the trap center.",0609484v1
+2006-10-16,Theoretical simulation of the anisotropic phases of antiferromagnetic thin films,"We simulate antiferromagnetic thin films. Dipole-dipole and antiferromagnetic
+exchange interactions as well as uniaxial and quadrupolar anisotropies are
+taken into account. Various phases unfold as the corresponding parameters, J, D
+and C, as well as the temperature T and the number n of film layers vary. We
+find (1) how the strength Delta_m of the anisotropy arising from dipole-dipole
+interactions varies with the number of layers m away from the film's surface,
+with J and with n; (2) a unified phase diagram for all n-layer films and bulk
+systems; (3) a layer dependent spin reorientation (SR) phase in which spins
+rotate continuously as T, D, C and n vary; (4) that the ratio of the SR to the
+ordering temperature depends (approximately) on n only through (D+Delta/n)/C,
+and hardly on J; (5) a phase transformation between two different magnetic
+orderings, in which spin orientations may or may not change, for some values of
+J, by varying n.",0610418v1
+2006-10-17,Universal Anisotropy in Force Networks under Shear,"Scaling properties of patterns formed by large contact forces are studied as
+a function of the applied shear stress, in two-dimensional static packings
+generated from the force network ensemble. An anisotropic finite-size-scaling
+analysis shows that the applied shear does not affect the universal scaling
+properties of these patterns, but simply induces different length scales in the
+principal directions of the macroscopic stress tensor. The ratio of these
+length scales quantifies the anisotropy of the force networks, and is found not
+to depend on the details of the underlying contact network, in contrast with
+other properties such as the yield stress.",0610483v2
+2006-10-23,Influence of external magnetic fields on growth of alloy nanoclusters,"Kinetic Monte Carlo simulations are performed to study the influence of
+external magnetic fields on the growth of magnetic fcc binary alloy
+nanoclusters with perpendicular magnetic anisotropy. The underlying kinetic
+model is designed to describe essential structural and magnetic properties of
+CoPt_3-type clusters grown on a weakly interacting substrate through molecular
+beam epitaxy. The results suggest that perpendicular magnetic anisotropy can be
+enhanced when the field is applied during growth. For equilibrium bulk systems
+a significant shift of the onset temperature for L1_2 ordering is found, in
+agreement with predictions from Landau theory. Stronger field induced effects
+can be expected for magnetic fcc-alloys undergoing L1_0 ordering.",0610589v1
+2006-10-24,Ferrimagnetic and Long Period Antiferromagnetic Phases in High Spin Heisenberg Chains with D-Modulation,"The ground state properties of the high spin Heisenberg chains with
+alternating single site anisotropy are investigated by means of the numerical
+exact daigonaization and DMRG method. It is found that the ferrimagnetic state
+appears between the Haldane phase and period doubled N\'eel phase for the
+integer spin chains. On the other hand, the transition from the
+Tomonaga-Luttinger liquid state into the ferrimagnetic state takes place for
+the half-odd-integer spin chains. In the ferrimagnetic phase, the spontaneous
+magnetization varies continuously with the modulation amplitude of the single
+site anisotropy. Eventually, the magnetization is locked to fractional values
+of the saturated magnetization. These fractional values satisfy the
+Oshikawa-Yamanaka-Affleck condition. The local spin profile is calculated to
+reveal the physical nature of each state. In contrast to the case of
+frustration induced ferrimagnetism, no incommensurate magnetic superstructure
+is found.",0610660v1
+2006-11-02,Order from Disorder in Graphene Quantum Hall Ferromagnet,"Valley-polarized quantum Hall states in graphene are described by a
+Heisenberg O(3) ferromagnet model, with the ordering type controlled by the
+strength and sign of valley anisotropy. A mechanism resulting from electron
+coupling to strain-induced gauge field, giving leading contribution to the
+anisotropy, is described in terms of an effective random magnetic field aligned
+with the ferromagnet z axis. We argue that such random field stabilizes the XY
+ferromagnet state, which is a coherent equal-weight mixture of the $K$ and $K'$
+valley states. Other implications such as the Berezinskii-Kosterlitz-Thouless
+ordering transition and topological defects with half-integer charge are
+discussed.",0611062v1
+2006-11-06,Universality class of isotropic on-lattice Eden clusters,"The shape of large on-lattice Eden clusters grown from a single seed is ruled
+by the underlying lattice anisotropy. This is reflected on the linear growth
+with time of the interface width ($w\sim t$), in contrast with the KPZ
+universality class ($w\sim t^{1/3}$) observed when the Eden model is grown on
+flat substrates. We propose an extended Eden model, in which the growth
+probability has a power law dependence with the number of occupied nearest
+neighbors. Large scale simulations ($N\gtrsim 4\times 10^9$ particles) were
+used to determine the time evolution of $w$. We found that a suitable choice of
+the power exponent removes the lattice-induced cluster anisotropy and provides
+a growth exponent in very good agreement with the KPZ universality class. Also,
+the present model corroborates the results found in off-lattice simulations, in
+which the center of mass fluctuations are considered in the interface scaling
+analysis.",0611160v1
+2006-11-13,Anisotropic properties of the layered superconductor Cu0.07TiSe2,"The anisotropic superconducting properties of single crystals of Cu0.07TiSe2
+were studied by measurements of magnetization and electrical resistivity. TC is
+around 3.9 K, and the measured upper critical field (Hc2) values are ~1.25 T
+and 0.8 T, for applied field parallel and perpendicular to the TiSe2 planes,
+respectively. The anisotropy ratio gamma_anis = H^ab_c2 / H^c_c2 is close to
+1.6 and nearly temperature independent. The lower critical field (Hc1) values
+are much smaller (~ 32 Oe for H||ab and 17 Oe for H||c); demagnetizing
+corrections for field perpendicular to the thin plate crystals are required for
+the determination of H^c_c1. The anisotropy of the critical fields is described
+well by the anisotropic Ginzburg-Landau (GL) theory, and the characteristic GL
+parameters are determined and discussed.",0611310v1
+2006-12-01,Antiferromagnetic Ising Model on Inverse Perovskite Lattice,"We study thermodynamic properties of an antiferromagnetic Ising model on the
+inverse perovskite lattice by using Monte Carlo simulations. The lattice
+structure is composed of corner-sharing octahedra and contains
+three-dimensional geometrical frustration in terms of magnetic interactions.
+The system with the nearest-neighbor interactions alone does not exhibit any
+phase transition, leading to a degenerate ground state with large residual
+entropy. The degeneracy is lifted by an external magnetic field or by an
+anisotropy in the interactions. Depending on the anisotropy, they stabilize
+either a 3D ferrimagnetic state or a partially-disordered antiferromagnetic
+(PDAF) state with a dimensionality reduction to 2D. By the degeneracy-lifting
+perturbations, all the transition temperatures of these different ordered
+states continuously grow from zero, leaving an unusual zero-temperature
+critical point at the unperturbed point. Such a zero-temperature
+multicriticality is not observed in other frustrated structures such as
+face-centered cubic and pyrochlore. The transition to the PDAF state is
+represented by either the first- or second-order boundaries separated by
+tricritical lines, whereas the PDAF phase shows 1/3 magnetization plateaus.",0612016v1
+2006-12-03,General analysis of the complementary nature of coercivity enhancement and exchange bias in ferro-antiferromagnet (F-AF) exchange coupled systems,"Complementary nature of coercivity enhancement and exchange bias is
+generalized from the layered systems to ferro-antiferromagnet (F-AF) exchange
+coupled systems with arbitrary configurations and is proved based on the
+coherent rotation of the F magnetization. In the proof, the effect of F-AF
+coupling is absorbed into the anisotropy of the F part, resulting in an
+arbitrary anisotropy for the F part. The proof starts from a general discussion
+on the initial susceptibility of a single domain particle. Then the fundamental
+correlation between the maximal initial susceptibility and the critical field
+along an arbitrary easy direction of a single domain particle, at which the
+magnetization becomes unstable, is discussed. Finally, the difference of the
+initial switching field and the actual switching field along the arbitrarily
+chosen easy direction is discussed.",0612062v1
+2006-12-04,Interplane and intraplane heat transport in quasi two-dimensional nodal superconductors,"We analyze the behavior of the thermal conductivity in quasi-two dimensional
+superconductors with line nodes. Motivated by measurements of the anisotropy
+between the interplane and intraplane thermal transport in CeIrIn_5 we show
+that a simple model of the open Fermi surface with vertical line nodes is
+insufficient to describe the data. We propose two possible extensions of the
+model taking into account a) additional modulation of the gap along the axial
+direction of the open Fermi surface; and b) dependence of the interplane
+tunneling on the direction of the in-plane momentum. We discuss the temperature
+dependence of the thermal conductivity anisotropy and its low T limit in these
+two models and compare the results with a model with a horizontal line of nodes
+(``hybrid gap''). We discuss possible relevance of each model for the symmetry
+of the order parameter in CeIrIn_5, and suggest further experiments aimed at
+clarifying the shape of the superconducting gap.",0612094v1
+2006-12-09,Field induced quantum phase transition in the anisotropic Kondo necklace model,"The anisotropic Kondo necklace model in 2D and 3D is treated as a genuine
+model for magnetic to Kondo singlet quantum phase transitions in the heavy
+fermion (HF) compounds. The variation of the quantum critical point (QCP) with
+anisotropy parameters has been investigated previously in the zero field case
+[1]. Here we extend the treatment to finite fields using a generalised bond
+operator representation including all triplet states. The variation of critical
+tc with external field H and the associated phase diagram is derived. The
+influence of anisotropies and the different g-factors for localised and
+itinerant spins on tc(H) is also investigated. It is found that three different
+types of behaviour may appear: (i) Destruction of antiferromangetism and
+appearance of a singlet state above a critical field. (ii) The inverese
+behaviour, namely field induced antiferromagnetism out of the Kondo singlet
+phase. (iii) Reentrance behaviour of the Kondo singlet phase as function of
+field strength.",0612230v2
+2007-01-04,Effect of the metal-to-wire ratio on the high-frequency magnetoimpedance of glass-coated CoFeBSi amorphous microwires,"High frequency [1-500 MHz] measurements of the magnetoimpedance (MI) of
+glass-coated Co$_{69.4}$Fe$_{3.7}$B$_{15.9}$Si$_{11}$ microwires are carried
+out with various metal-to-wire diameter ratios. A twin-peak, anhysteretic
+behaviour is observed as a function of magnetic field. A maximum in the
+normalized impedance, $\Delta Z$/$Z$, appears at different values of the
+frequency $f$, 125, 140 and 85 MHz with the corresponding diameter ratio $p$ =
+0.80, 0.55 and 0.32. We describe the measurement technique and interpret our
+results with a thermodynamic model that leads to a clearer view of the effects
+of $p$ on the maximum value of MI and the anisotropy field. The behavior of the
+real and imaginary components of impedance is also investigated; they display a
+resonance that becomes a function of the DC field $H_{DC}$ for values larger or
+equal to $H_{K}$ the circumferential anisotropy field for each $p $ value.
+These results are interpreted in terms of a rotation model of the outer shell
+magnetization.",0701077v2
+2007-01-04,Magnetic Susceptibility of the Kagome Antiferromagnet ZnCu3(OH)6Cl2,"We analyze the experimental data for the magnetic susceptibility of the
+material ZnCu3(OH)6Cl2 in terms of the Kagome Lattice Heisenberg model (KLHM),
+discussing possible role of impurity spins, dilution, exchange anisotropy, and
+both out-of-plane and in-plane Dzyaloshinsky-Moriya (DM) anisotropies, with
+explicit theoretical calculations using the Numerical Linked Cluster (NLC)
+method and exact diagonalization (ED). The high-temperature experimental data
+are well described by the pure Heisenberg model with J=170 K. We show that the
+sudden upturn in the susceptibility around T=75 K is due to DM interactions. We
+also observe that at intermediate temperatures, below T=J, our calculated
+susceptibility for KLHM fits well with a power law T^{-0.25}.",0701087v3
+2007-01-10,Brillouin scattering and molecular dynamics study of the elastic properties of Pb(Mg1/3Nb2/3)O3,"We report the complete set of elastic constants and the bulk modulus for
+single crystal Pb(Mg1/3Nb2/3)O3 (PMN) at room temperature obtained from
+Brillouin spectroscopy and molecular dynamics (MD) simulations. The bulk
+modulus from Brillouin is found to be 103 GPa, in a good agreement with earlier
+x-ray studies. We also derived the refractive index along all principal axes
+and found PMN to be optically isotropic, with a refractive index of 2.52 +/-
+0.02. PMN shows mechanical anisotropy with A=1.7. The MD simulations of PMN
+using the random site model overestimate the elastic constants by 20-50 GPa and
+the bulk modulus is 148 GPa, but the mechanical anisotropy matches the
+Brillouin results of A = 1.7. We also determined the elastic constants for
+various models of PMN and we find variation in the elastic constants based on
+chemical ordering.",0701223v1
+2007-01-11,Long-range correlated random field and random anisotropy O(N) models: A functional renormalization group study,"We study the long-distance behavior of the O(N) model in the presence of
+random fields and random anisotropies correlated as ~1/x^{d-sigma} for large
+separation x using the functional renormalization group. We compute the fixed
+points and analyze their regions of stability within a double epsilon=d-4 and
+sigma expansion. We find that the long-range disorder correlator remains
+analytic but generates short-range disorder whose correlator develops the usual
+cusp. This allows us to obtain the phase diagrams in (d,sigma,N) parameter
+space and compute the critical exponents to first order in epsilon and sigma.
+We show that the standard renormalization group methods with a finite number of
+couplings used in previous studies of systems with long-range correlated random
+fields fail to capture all critical properties. We argue that our results may
+be relevant to the behavior of He-3A in aerogel.",0701256v3
+2007-01-14,Sr1.5Ba0.5Zn2Fe12O22 Hexaferrites Ferromagnetic Resonance and Nonlinear Excitation for Magneto-Electric Devices,"A magneto electric (ME) effect was reported [1] for the insulator material of
+helimagnetic hexaferrite of Sr1.5Ba0.5Zn2Fe12O22. In this study we are
+interested in investigating this materials ferromagnetic resonance to define
+its internal anisotropy fields. By using a vibrating sample magnetometer (VSM)
+and ferromagnetic resonance (FMR) analysis we realized that this helical
+hexaferrite has about -0.5 kOe exchange anisotropy field of HE. Also, by using
+an alternative free energy model we derived this materials Polder tensor and
+its ferromagnetic resonance condition. Meanwhile, we were able to show a
+potential magneto electric coupling by nonlinear excitation of planar helical
+hexaferrite, in which a magnetic nonlinear excitation is integrated into
+dielectric permittivity.
+  Index Terms, Ferrites, ferromagnetic resonances, and magnetic nonlinear
+excitations.",0701309v2
+2007-01-30,Magnetic Excitations in the Spin-1 Anisotropic Heisenberg Antiferromagnetic Chain System NiCl$_2$-4SC(NH$_2$)$_2$,"NiCl$_2$-4SC(NH$_2$)$_2$ (DTN) is a quantum S=1 chain system with strong
+easy-pane anisotropy and a new candidate for the Bose-Einstein condensation of
+the spin degrees of freedom. ESR studies of magnetic excitations in DTN in
+fields up to 25 T are presented. Based on analysis of the single-magnon
+excitation mode in the high-field spin-polarized phase and previous
+experimental results [Phys. Rev. Lett. 96, 077204 (2006)], a revised set of
+spin-Hamiltonian parameters is obtained. Our results yield $D=8.9$ K, $J_c=2.2$
+K, and $J_{a,b}=0.18$ K for the anisotropy, intrachain, and interchain exchange
+interactions, respectively. These values are used to calculate the
+antiferromagnetic phase boundary, magnetization and the frequency-field
+dependence of two-magnon bound-state excitations predicted by theory and
+observed in DTN for the first time. Excellent quantitative agreement with
+experimental data is obtained.",0701750v1
+2007-02-27,Creep and flow regimes of magnetic domain wall motion in ultrathin Pt/Co/Pt films with perpendicular anisotropy,"We report on magnetic domain wall velocity measurements in ultrathin
+Pt/Co(0.5-0.8 nm)/Pt films with perpendicular anisotropy over a large range of
+applied magnetic fields. The complete velocity-field characteristics are
+obtained, enabling an examination of the transition between thermally activated
+creep and viscous flow: motion regimes predicted from general theories for
+driven elastic interfaces in weakly disordered media. The dissipation limited
+flow regime is found to be consistent with precessional domain wall motion,
+analysis of which yields values for the damping parameter, $\alpha$.",0702654v2
+2007-03-05,In-plane optical anisotropy due to conduction band electron wavefunctions,"Photoluminescence measurements were carried out on Be $\delta$-doped
+  GaAs/Al$_{0.33}$Ga$_{0.67}$As heterostructure at 1.6 K in magnetic fields
+($B$) up to 5 T. Luminescence originating from recombination of a
+two-dimensional electron gas (2DEG) and photo excited holes localized on Be
+acceptors was analyzed. The degree of circular polarization ($\gamma_C$) of the
+luminescence from fully occupied Landau levels was determined as a function of
+$B$ and the 2DEG concentration, $n_s$. At $B$ constant, $\gamma_C$ decreased
+with the increase of $n_s$. Two mechanisms of the $\gamma_C(n_s)$ dependence
+are discussed: a) the Stark effect on a photo excited hole bound to Be acceptor
+and b) the in-plane anisotropy of the intensity of optical transitions. A
+quantitative analysis shows that the influence of the Stark effect on
+$\gamma_C$ is negligible in the present experiment. We propose that the
+$\gamma_C(n_s)$ dependence results from the $C_{2v}$ symmetry of conduction
+band electron wavefunctions and we give qualitative arguments supporting this
+interpretation.",0703088v1
+2007-03-19,Electron states in quantum rings with defects under axial or in-plane magnetic fields,"A comprehensive study of anisotropic quantum rings, QRs, subject to axial and
+in-plane magnetic field, both aligned and transverse to the anisotropy
+direction, is carried out. Elliptical QRs for a wide range of eccentricity
+values and also perfectly circular QRs including one or more barriers
+disturbing persistent QR current are considered. These models mimic anisotropic
+geometry deformations and mass diffusion occuring in the QR fabrication
+process. Symmetry considerations and simplified analytical models supply
+physical insight into the obtained numerical results. Our study demonstrates
+that, except for unusual extremely large eccentricities, QR geometry
+deformations only appreciably influence a few low-lying states, while the
+effect of barriers disturbing the QR persistent current is stronger and affects
+all studied states to a similar extent. We also show that the response of the
+electron states to in-plane magnetic fields provides accurate information on
+the structural anisotropy.",0703484v1
+2007-03-23,Transition-metal dimers and physical limits on magnetic anisotropy,"Recent advances in nanoscience have raised interest in the minimum bit size
+required for classical information storage, i.e. for bistability with
+suppressed quantum tunnelling and energy barriers that exceed ambient
+temperatures. In the case of magnetic information storage much attention has
+centred on molecular magnets[1] with bits consisting of ~ 100 atoms, magnetic
+uniaxial anisotropy energy barriers ~ 50 K, and very slow relaxation at low
+temperatures. In this article we draw attention to the remarkable magnetic
+properties of some transition metal dimers which have energy barriers
+approaching ~ 500 K with only two atoms. The spin dynamics of these ultra small
+nanomagnets is strongly affected by a Berry phase which arises from
+quasi-degeneracies at the electronic Highest Occupied Molecular Orbital (HOMO)
+energy. In a giant spin-approximation, this Berry phase makes the effective
+reversal barrier thicker. [1] Gatteschi, D., Sessoli, R. & Villain, J.
+Molecular Nanomagnets. (Oxford, New York 2006).",0703607v2
+2007-03-26,Exact results of the mixed-spin Ising model on a decorated square lattice with two different decorating spins of integer magnitudes,"The mixed-spin Ising model on a decorated square lattice with two different
+decorating spins of the integer magnitudes S_B = 1 and S_C = 2 placed on
+horizontal and vertical bonds of the lattice, respectively, is examined within
+an exact analytical approach based on the generalized decoration-iteration
+mapping transformation. Besides the ground-state analysis, finite-temperature
+properties of the system are also investigated in detail. The most interesting
+numerical result to emerge from our study relates to a striking critical
+behaviour of the spontaneously ordered 'quasi-1D' spin system. It was found
+that this quite remarkable spontaneous order arises when one sub-lattice of the
+decorating spins (either S_B or S_C) tends towards their 'non-magnetic' spin
+state S = 0 and the system becomes disordered only upon further single-ion
+anisotropy strengthening. The effect of single-ion anisotropy upon the
+temperature dependence of the total and sub-lattice magnetization is also
+particularly investigated.",0703663v2
+2007-03-28,Field-induced level crossings in spin clusters: Thermodynamics and magneto-elastic instability,"Quantum spin clusters with dominant antiferromagnetic Heisenberg exchange
+interactions typically exhibit a sequence of field-induced level crossings in
+the ground state as function of magnetic field. For fields near a level
+crossing, the cluster can be approximated by a two-level Hamiltonian at low
+temperatures. Perturbations, such as magnetic anisotropy or spin-phonon
+coupling, sensitively affect the behavior at the level-crossing points. The
+general two-level Hamiltonian of the spin system is derived in first-order
+perturbation theory, and the thermodynamic functions magnetization, magnetic
+torque, and magnetic specific heat are calculated. Then a magneto-elastic
+coupling is introduced and the effective two-level Hamilitonian for the
+spin-lattice system derived in the adiabatic approximation of the phonons. At
+the level crossings the system becomes unconditionally unstable against lattice
+distortions due to the effects of magnetic anisotropy. The resultant
+magneto-elastic instabilities at the level crossings are discussed, as well as
+the magnetic behavior.",0703747v1
+1993-11-02,Graviton Mode Function in Inflationary Cosmology,"We consider the production of gravitons in an inflationary cosmology by
+approximating each epoch of change in the equation of state as sudden, from
+which a simple analytic graviton mode function has been derived. We use this
+mode function to compute the graviton spectral energy density and the
+tensor-induced cosmic microwave background anisotropy. The results are then
+compared to the numerical calculations which incorporate a smooth
+radiation-matter phase transition. We find that the sudden approximation is a
+fairly good method. Besides, in determining the frequency range and amplitude
+of the mode function, we introduce a pre-inflationary radiation-dominated epoch
+and use a physically sensible regularization method.",9311002v3
+1994-12-21,Photon rockets and gravitational radiation,"The absence of gravitational radiation in Kinnersley's ``photon rocket''
+solution of Einstein's equations is clarified by studying the mathematically
+well-defined problem of point-like photon rockets in Minkowski space (i.e.
+massive particles emitting null fluid anisotro\-pically and accelerating
+because of the recoil). We explicitly compute the (uniquely defined) {\it
+linearized} retarded gravitational waves emitted by such objects, which are the
+coherent superposition of the gravitational waves generated by the motion of
+the massive point-like rocket and of those generated by the energy-momentum
+distribution of the photon fluid. In the special case (corresponding to
+Kinnersley's solution) where the anisotropy of the photon emission is purely
+dipolar we find that the gravitational wave amplitude generated by the
+energy-momentum of the photons exactly cancels the usual $1/r$ gravitational
+wave amplitude generated by the accelerated motion of the rocket. More general
+photon anisotropies would, however, generate genuine gravitational radiation at
+infinity. Our explicit calculations show the compatibility between the
+non-radiative character of Kinnersley's solution and the currently used
+gravitational wave generation formalisms based on post-Minkowskian perturbation
+theory.",9412063v1
+1996-04-15,On compatibility of the Kaluza-Klein approach with the COBE experiment,"Contributions of primordial gravitational waves to the large-angular-scale
+anisotropies of the cosmic microwave background radiation in multidimensional
+cosmological models (Kaluza-Klein models) are studied. We derive limits on free
+parameters of the models using results of the COBE experiment and other
+astrophysical data. It is shown that in principle there is a room for
+Kaluza-Klein models as possible candidates for the description of the Early
+Universe. However, the obtained limits are very restrictive. Assuming that the
+anisotropies are mostly due to gravitational waves, none of the concrete
+models, analyzed in the article, satisfy them. On the other hand, if the
+contribution of gravitational waves is very small then a string inspired model
+is not ruled out.",9604031v1
+1996-06-14,Anisotropy of fast-going processes in the Sun and new interaction in nature,"The processing of the galactic coordinates of 3543 solar flares with a
+magnitude of 2 or more has shown that the distribution of these fast-going
+processes on the surface of the ""nonrotating"" Sun is irregular and non-random
+what testifies that in the near-Sun space an anisotropy takes place which
+practically coincides with that predicted and obtained in laboratory
+experiments and caused by existence of the intergalactic vector potential ${\bf
+A_g}$.",9606033v1
+1997-01-03,Semiclassical effects in black hole interiors,"First-order semiclassical perturbations to the Schwarzschild black hole
+geometry are studied within the black hole interior. The source of the
+perturbations is taken to be the vacuum stress-energy of quantized scalar,
+spinor, and vector fields, evaluated using analytic approximations developed by
+Page and others (for massless fields) and the DeWitt-Schwinger approximation
+(for massive fields). Viewing the interior as an anisotropic collapsing
+cosmology, we find that minimally or conformally coupled scalar fields, and
+spinor fields, decrease the anisotropy as the singularity is approached, while
+vector fields increase the anisotropy. In addition, we find that massless
+fields of all spins, and massive vector fields, strengthen the singularity,
+while massive scalar and spinor fields tend to slow the growth of curvature.",9701004v1
+1997-01-16,Cosmological Limits on Slightly Skew Stresses,"We present an analysis of the cosmological evolution of matter sources with
+small anisotropic pressures. This includes electric and magnetic fields,
+collisionless relativistic particles, gravitons, antisymmetric axion fields in
+low-energy string cosmologies, spatial curvature anisotropies, and stresses
+arising from simple topological defects. We calculate their evolution during
+the radiation and dust eras of an almost isotropic universe. In many
+interesting cases the evolution displays a special critical behaviour created
+by the non-linear evolution of the pressure and expansion anisotropies. The
+isotropy of the microwave background is used to place strong limits of order
+$\Omega _{a0}\leq 5\times 10^{-6}\Delta (1+z_{rec})^{-\Delta }$on the possible
+contribution of these matter sources to the total density of the universe,
+where $1\leq \Delta \leq 3$ characterises the anisotropic stress. The present
+abundance of an anisotropic stress which becomes non-relativistic at a
+characteristic low-energy scale is also calculated. We explain why the limits
+obtained from primordial nucleosynthesis are generally weaker than those
+imposed by the microwave background isotropy. The effect of inflation on these
+stresses is also calculated.",9701038v1
+1997-02-21,Chaos in Anisotropic Pre-Inflationary Universes,"We study the dynamics of anisotropic Bianchi type-IX models with matter and
+cosmological constant. The models can be thought as describing the role of
+anisotropy in the early stages of inflation. The concurrence of the
+cosmological constant and anisotropy are sufficient to produce a chaotic
+dynamics in the gravitational degrees of freedom, connected to the presence of
+a critical point of saddle-center type in the phase space of the system. The
+invariant character of chaos is guaranteed by the topology of the cylinders
+emanating from unstable periodic orbits in the neighborhood of the
+saddle-center. We discuss a possible mechanism for amplification of specific
+wavelengths of inhomogeneous fluctuations in the models. A geometrical
+interpretation is given for Wald's inequality in terms of invariant tori and
+their destruction by increasing values of the cosmological constant.",9702044v1
+1998-01-28,Lensing and caustic effects on cosmological distances,"We consider the changes which occur in cosmological distances due to the
+combined effects of some null geodesics passing through low-density regions
+while others pass through lensing-induced caustics. This combination of effects
+increases observed areas corresponding to a given solid angle even when
+averaged over large angular scales, through the additive effect of increases on
+all scales, but particularly on micro-angular scales; however angular sizes
+will not be significantly effected on large angular scales (when caustics
+occur, area distances and angular-diameter distances no longer coincide). We
+compare our results with other works on lensing, which claim there is no such
+effect, and explain why the effect will indeed occur in the (realistic)
+situation where caustics due to lensing are significant. Whether or not the
+effect is significant for number counts depends on the associated angular
+scales and on the distribution of inhomogeneities in the universe. It could
+also possibly affect the spectrum of CBR anisotropies on small angular scales,
+indeed caustics can induce a non-Gaussian signature into the CMB at small
+scales and lead to stronger mixing of anisotropies than occurs in weak lensing.",9801092v1
+1998-05-25,Speed of light on rotating platforms,"It is often taken for granted that on board a rotating disk it is possible to
+operate a \QTR{it}{global}3+1 splitting of space-time, such that both lengths
+and time intervals are \QTR{it}{uniquely} defined in terms of measurements
+performed by real rods and real clocks at rest on the platform. This paper
+shows that this assumption, although widespread and apparently trivial, leads
+to an anisotropy of the velocity of two light beams travelling in opposite
+directions along the rim of the disk; which in turn implies some recently
+pointed out paradoxical consequences undermining the self-consistency of the
+Special Theory of Relativity (SRT). A correct application of the SRT solves the
+problem and recovers complete internal consistency for the theory. As an
+immediate consequence, it is shown that the Sagnac effect only depends on the
+non homogeneity of time on the platform and has nothing to do with any
+anisotropy of the speed of light along the rim of the disk, contrary to an
+incorrect but widely supported idea.",9805089v1
+1999-12-23,Generation of the Scalar Field and Anisotropy at Quantum Creation of the Closed Universe,"The behaviour of the wave function of the Universe under the barrier for
+anisotropic cosmological Bianchi type IX model with account of influence of the
+scalar field is explored. In view of known difficulties with interpretation of
+multidimensional wave functions the method of reduction of such problems to
+one-dimensional is offered. For this purpose in frameworks of semiclassical
+approach the system of characteristics equations relative to one variable is
+written out. This system describe a bundle of the characteristics along which
+the multidimensional problem is reduced to one-dimensional one that allows to
+utillize the standard interpretation of the wave function as well as for usual
+Schrodinger equation. The obtained results for Bianchi type IX model are
+reduced to the following statement: the Universe tunnels through the barrier
+from an isotropic state with zero initial value of the scalar field and appear
+in classically allowed region with small anisotropy that is necessary for
+providing of long-lived inflation for deriving the Universe such as ours.",9912098v1
+2001-03-15,Locally Anisotropic Wormholes and Flux Tubes in 5D Gravity,"In this article we examine a class of wormhole and flux tube like solutions
+to 5D vacuum Einstein equations. These solutions possess generic local
+anisotropy, and their local isotropic limit is shown to be conformally
+equivalent to the spherically symmetric 5D solutions of gr-qc/9807086. The
+anisotropic solutions investigated here have two physically distinct
+signatures: First, they can give rise to angular-dependent, anisotropic
+``electromagnetic'' interactions. Second, they can result in a gravitational
+running of the ``electric'' and ``magnetic'' charges of the solutions. This
+gravitational running of the electromagnetic charges is linear rather than
+logarithmic, and could thus serve as an indirect signal for the presence of
+higher dimensions. The local anisotropy of these solutions is modeled using the
+technique of anholonomic frames with respect to which the metrics are
+diagonalized. If holonomic coordinates frames were used then such metrics would
+have off-diagonal components.",0103058v3
+2001-06-21,Anholonomic Frames and Thermodynamic Geometry of 3D Black Holes,"We study new classes three dimensional black hole solutions of Einstein
+equations written in two holonomic and one anholonomic variables with respect
+to anholonomic frames Thermodynamic properties of such (2+1)-black holes with
+generic local anisotropy (having elliptitic horizons) are studied by applying
+geometric methods. The corresponding thermodynamic systems are three
+dimensional with entropy S being a hypersurface function on mass M, anisotropy
+angle $\theta$ and eccentricity of elliptic deformations $\epsilon >.$
+Two-dimensional curved thermodynamic geometries for locally anistropic deformed
+black holes are constructed after integration on anisotropic parameter
+$\theta$. Two approaches, the first one based on two-dimensional hypersurface
+parametric geometry and the second one developed in a
+Ruppeiner-Mrugala-Janyszek fashion, are analyzed. The thermodynamic curvatures
+are computed and the critical points of curvature vanishing are defined.",0106069v3
+2001-12-12,Spinors and Space-Time Anisotropy,"This is the first monograph on the geometry of anisotropic spinor spaces and
+its applications in modern physics. The main subjects are the theory of gravity
+and matter fields in spaces provided with off--diagonal metrics and associated
+anholonomic frames and nonlinear connection structures, the algebra and
+geometry of distinguished anisotropic Clifford and spinor spaces, their
+extension to spaces of higher order anisotropy and the geometry of gravity and
+gauge theories with anisotropic spinor variables. The book summarizes the
+authors' results and can be also considered as a pedagogical survey on the
+mentioned subjects.",0112028v3
+2002-02-04,Anisotropic quantum cosmological models: a discrepancy between many-worlds and dBB interpretations,"In the isotropic quantum cosmological perfect fluid model, the initial
+singularity can be avoided, while the classical behaviour is recovered
+asymptotically. We verify if initial anisotropies can also be suppressed in a
+quantum version of a classical anisotropic model where gravity is coupled to a
+perfect fluid. Employing a Bianchi I cosmological model, we obtain a
+""Schr\""odinger-like"" equation where the matter variables play de role of time.
+This equation has a hyperbolic signature. It can be explicitly solved and a
+wave packet is constructed. The expectation value of the scale factor,
+evaluated in the spirit of the many-worlds interpretation, reveals an isotropic
+Universe. On the other hand, the bohmian trajectories indicate the existence of
+anisotropies. This is an example where the Bohm-de Broglie and the many-worlds
+interpretations are not equivalent. It is argued that this inequivalence is due
+to the hyperbolic structure of the ""Schr\""odinger-like"" equation.",0202009v1
+2003-02-17,Galactic Potentials,"The information contained in galactic rotation curves is examined under a
+minimal set of assumptions. If emission occurs from stable circular geodesic
+orbits of a static spherically symmetric field, with information propagated to
+us along null geodesics, observed rotation curves determine galactic potentials
+without specific reference to any metric theory of gravity. Given the
+potential, the gravitational mass can be obtained by way of an anisotropy
+function of this field. The gravitational mass and anisotropy function can be
+solved for simultaneously in a Newtonian limit without specifying any specific
+source. This procedure, based on a minimal set of assumptions, puts very strong
+constraints on any model of the ""dark matter"".",0302067v5
+2003-04-11,Anisotropic brane cosmologies with exponential potentials,"We study Bianchi I type brane cosmologies with scalar matter self-interacting
+through combinations of exponential potentials. Such models correspond in some
+cases to inflationary universes. We discuss the conditions for accelerated
+expansion to occur, and pay particular attention to the influence of extra
+dimensions and anisotropy. Our results show that the associated effects evolve
+in such a way that they become negligible in the late time limit, those related
+to the anisotropy disappearing earlier. This study focuses mainly on single
+field models, but we also consider a generalization yielding models with
+multiple non-interacting fields and examine its features briefly. We conclude
+that in the brane scenario, as happens in general relativity, an increase in
+the number of fields assists inflation.",0304046v2
+2004-11-10,On the Tensor/Scalar Ratio in Inflation with UV Cutoff,"Anisotropy of the cosmic microwave background radiation (CMB) originates from
+both tensor and scalar perturbations. To study the characteristics of each of
+these two kinds of perturbations, one has to determine the contribution of each
+to the anisotropy of CMB. For example, the ratio of the power spectra of
+tensor/scalar perturbations can be used to tighten bounds on the scalar
+spectral index. We investigate here the implications for the tensor/scalar
+ratio of the recent discovery (noted in astro-ph/0410139) that the introduction
+of a minimal length cutoff in the structure of spacetime does not leave
+boundary terms invariant. Such a cutoff introduces an ambiguity in the choice
+of action for tensor and scalar perturbations, which in turn can affect this
+ratio. We numerically solve for both tensor and scalar mode equations in a
+near-de-sitter background and explicitly find the cutoff dependence of the
+tensor/scalar ratio during inflation.",0411056v4
+1998-04-17,Perturbative and non-perturbative studies of the SU(2)-Higgs model on lattices with asymmetric lattice spacings,"We present a calculation of the O(g^2,\lambda) perturbative corrections to
+the coupling anisotropies of the SU(2)-Higgs model on lattices with asymmetric
+lattice spacings. These corrections are obtained by a one-loop calculation
+requiring the rotational invariance of the gauge and Higgs boson propagators in
+the continuum limit. The coupling anisotropies are also determined from
+numerical simulations of the model on appropriate lattices. The one-loop
+perturbation theory and the simulation results agree with high accuracy. It is
+demonstrated that rotational invariance is also restored for the static
+potential determined from space-space and space-time Wilson loops.",9804026v2
+1998-10-14,Anisotropic Improved Gauge Actions; --Perturbative and Numerical Studies --,"The $\Lambda$ parameter on the anisotropic lattice, the spatial and
+temperature coupling constant $g_{\sigma}$, $g_{\tau}$ and their derivative
+with respaect to the the anisotropy parameter $\xi$ are studied perturbatively
+for the class of improved actions, which cover tree level Symanzik's, Iwasaki's
+and QCDTARO's improved actions. The $\eta(=g_{\tau}/g_{\sigma})$ becomes less
+than 1 for Iwasaki's and QCDTARO's action, which is confirmed nonperturbatively
+by numerical simulations. Derivatives of the coupling constants with respect to
+the anisotropy parameter, $\partial g_{\tau}/\partial \xi$ and $\partial
+g_{\sigma}/\partial \xi$, change sign for those improved actions.",9810030v3
+2000-10-28,Perfect Gauge Actions on Anisotropic Lattices,"On anisotropic lattices, where generally the lattice is rather coarse in
+spatial directions, a parametrized classically perfect action could help
+reducing lattice artifacts considerably. We investigate the possibility of
+constructing such actions for SU(3) gauge theory. We present two different
+methods to do so, either repeating the procedure used to create our newly
+parametrized isotropic FP action, or performing one single step starting with
+the isotropic result. The anisotropic action is parametrized using an ansatz
+including anisotropically APE-like smeared (``fat'') links. The parametrized
+classically perfect action with anisotropy $\xi=a_s/a_t=2$ is constructed and
+the renormalized anisotropy is measured using the torelon dispersion relation.
+It turns out that the renormalization is small.",0010057v1
+2001-10-21,O(a) improved Wilson quark action on anisotropic lattice,"The $O(a)$ improved Wilson quark action on the anisotropic lattice is
+investigated. We carry out numerical simulations in the quenched approximation
+at three values of lattice spacing ($a_{\sigma}^{-1}=1$--2 GeV) with the
+anisotropy $\xi=a_{\sigma}/a_{\tau}=4$, where $a_{\sigma}$ and $a_{\tau}$ are
+the spatial and the temporal lattice spacings, respectively. Using the
+dispersion relation of mesons, the bare anisotropy $\gamma_F$ in the quark
+action is numerically tuned below the charm quark mass region with the
+statistical accuracy of 1 % level. The systematic uncertainties in the
+calibration are examined and found to be under control in the continuum limit.
+Then we compute the light hadron masses and find that they are consistent with
+the result of the UKQCD Collaboration on the isotropic lattice. The effect of
+the uncertainty in the calibration on the hadron spectrum for physical quark
+masses is also found to be under control.",0110176v1
+2002-09-08,Heavy-light meson in anisotropic lattice QCD,"We examine whether the $O(a)$ improved quark action on anisotropic lattices
+can be used as a framework for the heavy quark, which enables precision
+computation of matrix elements of heavy-light mesons. To this end, it is
+crucial to verify that a mass independent and nonperturbative tuning of the
+parameters is possible. As a first step, we observe the dispersion relation of
+heavy-light mesons on a quenched lattice using the action which is
+nonperturbatively tuned only for the leading terms. On a lattice with the
+spatial cutoff $a_\sigma^{-1} \simeq$ 1.6 GeV and the anisotropy $\xi=4$, the
+relativity relation holds within 2% accuracy in the quark mass region $a_\sigma
+m_Q \leq 1.2$ with the bare anisotropy parameter tuned for the massless quark.
+We also apply the action to a calculation of heavy-light decay constants in the
+charm quark mass region.",0209090v1
+2003-01-30,Renormalization group improved action on anisotropic lattices,"We study a block spin transformation in the SU(3) lattice gauge theory on
+anisotropic lattices to obtain Iwasaki's renormalization group improved action
+for anisotropic cases. For the class of actions with plaquette and $1\times2$
+rectangular terms, we determine the improvement parameters as functions of the
+anisotropy $\xi= a_s/a_t$. We find that the program of improvement works well
+also on anisotropic lattices. From a study of an indicator which estimates the
+distance to the renormalized trajectory, we show that, for the range of the
+anisotropy $\xi \approx 1$--4, the coupling parameters previously determined
+for isotropic lattices improve the theory considerably.",0301029v2
+2003-11-13,Improved gauge action on an anisotropic lattice II - Anisotropy parameter in the medium coupling region -,"The quantum correction of the anisotropy parameter, $\eta$, is calculated for
+$\xi=2$ and 3 in the $\beta$ region where numerical simulations such as hadron
+spectroscopy are currently carried out, for the improved actions composed of
+plaquette and rectangular 6-link loops. The $\beta$ dependences of $\eta$ for
+the renormalization group improved actions are quite different from those of
+the standard and Symanzik actions. In Iwasaki and DBW2 actions, $\eta$ stays
+almost constant in a wide range of $\beta$, which also differs from the
+one-loop perturbative result, while in the case of Symanzik action, it
+increases as $\beta$ decreases, which is qualitatively similar to the
+perturbative result, but the slope is steeper. In the calculation of the $\eta$
+parameter close to and in the confined phase, we have applied the link
+integration method to suppress the fluctuation of the gauge fields. Some
+technical details are summarized.",0311020v1
+2004-07-21,QED in 2+1 Dimensions with Fermi and Gap Anisotropies,"QED in 2+1 dimensions has long been studied as a model field theory which
+exhibits both asymptotic freedom and non-trivial IR behaviour. There is also a
+trend towards viewing it as a candidate low energy effective theory for the
+pseudogap phase of high temperature superconductors. One feature of these
+theories is their lack of isotropy in the x and y directions (a common feature
+of Dirac theories in condensed matter systems). A model motivated by this work
+is outlined, and tentative evidence presented for chiral symmetry restoration
+as the relative anisotropy is increased.",0407029v1
+1992-06-18,The Implications of the COBE-DMR Results for Cosmic Strings,"We compare the anisotropies in the cosmic microwave background radiation
+measured by the COBE experiment to the predictions of cosmic strings. We use an
+analytic model for the $\Delta T/T$ power spectrum that is based on our
+previous numerical simulations to show that the COBE results imply a value for
+the string mass per unit length, $\mu$ under the assumption that cosmic strings
+are the source of the measured anisotropy. We find $G\mu = 1.5\pm 0.5 \times
+10^{-6}$ which is consistent with the value of $\mu$ thought to be required for
+cosmic strings to seed galaxy formation.",9206233v1
+1992-07-20,Inflation and Large Scale Structure Formation After COBE,"The simplest realizations of the new inflationary scenario typically give
+rise to primordial density fluctuations which deviate logarithmically from the
+scale free Harrison - Zeldovich spectrum. We consider a number of such examples
+and, in each case we normalize the amplitude of the fluctuations with the
+recent COBE measurement of the microwave background anisotropy. The predictions
+for the bulk velocities as well as anisotropies on smaller (~1-2 degrees)
+angular scales are compared with the Harrison-Zeldovich case. Deviations from
+the latter range from a few to about 15 percent. We also estimate the redshift
+beyond which the quasars would not be expected to be seen. The inflationary
+quasar cutoff redshifts can vary by as much as 25\% from the Harrison-Zeldovich
+case. We find that the inflationary scenario provides a good starting point for
+a theory of large scale structure in the universe provided the dark matter is a
+combination of cold plus (~10-30 \%) hot components.",9207247v1
+1993-03-11,Peculiar Velocities and Microwave Background Anisotropopies from Cosmic Strings,"Using an analytic model we show that the predictions of the cosmic string
+model for the peculiar velocities and the microwave background (MBR) anisotropy
+depend on similar combinations of string evolution parameters. Normalizing from
+the COBE detection of MBR anisotropy, and for certain reasonable values of
+string network evolution parameters, we find that the magnitude of predicted
+velocity flows is in good agreement with observations on small scales but is
+inconsistent with observations on large scales ($ > 50 h^{-1}$Mpc). The Cosmic
+Mach Number obtained from the cosmic string scenario is found to depend on a
+single network evolution parameter and is consistent with observations on
+scales $5h^{-1}$Mpc to $20h^{-1}$Mpc.",9303242v2
+1994-07-21,Non-Zero Electric Charge of the Neutrino and the Solar Neutrino Problem,"It has recently been shown that the neutrino can have non-zero electric
+charge in a number of gauge theories, including the Minimal Standard Model.
+Assuming non-zero neutrino charge, we develop a new approach to the solar
+neutrino problem. The key idea is that the charged neutrinos will be deflected
+by the Lorentz force while they are crossing the solar magnetic fields. Such a
+deflection will result in the anisotropy of the solar neutrino flux. Because of
+this anisotropy, the solar neutrino flux registered on earth can be reduced as
+compared to the Standard Solar Model prediction. The mechanism is purely
+classical and does not require neutrino oscillations, spin-flip or neutrino
+decay. We discuss qualitatively the consequences of our scenario for present
+and future solar neutrino experiments as well as differences between our
+mechanism and other proposed solutions.",9407346v1
+1996-06-20,What would we learn by detecting a gravitational wave signal in the cosmic microwave background anisotropy?,"Inflation generates gravitational waves, which may be observable in the low
+multipoles of the cosmic microwave background (cmb) anisotropy but only if the
+inflaton field variation is at least of order the Planck scale. Such a large
+variation would imply that the model of inflation cannot be part of an ordinary
+extension of the standard model, and combined with the detection of the waves
+it would also suggest that the inflaton field cannot be one of the superstring
+moduli. Another implication of observable gravitational waves would be a
+potential $V^{1/4}=2$ to $4\times 10^{16}\GeV$, which is orders of magnitude
+bigger than is expected on the basis of particle theory. It might emerge in a
+hybrid inflation model where most of the energy density comes from the Higgs
+sector of a GUT, but only if both the vacuum expectation values {\em and the
+masses } of the Higgs fields are of this order.",9606387v1
+1996-10-22,$\eps$ expansion analysis of very weak first-order transitions in the cubic anisotropy model: Part I,"The cubic anisotropy model provides a simple example of a system with an
+arbitrarily weak first-order phase transition. We present an analysis of this
+model using $\eps$-expansion techniques with results up to
+next-to-next-to-leading order in $\eps$. Specifically, we compute the relative
+discontinuity of various physical quantities across the transition in the limit
+that the transition becomes arbitrarily weakly first-order. This provides a
+useful test-bed for the application of the $\eps$ expansion in weakly
+first-order transitions.",9610447v2
+1997-03-05,Cosmic Ray and Neutrino Tests of Special Relativity,"Searches for anisotropies due to Earth's motion relative to a preferred frame
+-- modern versions of the Michelson-Morley experiment -- provide precise
+verifications of special relativity. We describe other tests, independent of
+this motion, that are or can become even more sensitive. The existence of
+high-energy cosmic rays places strong constraints on Lorentz non-invariance.
+Furthermore, if the maximum attainable speed of a particle depends on its
+identity, then neutrinos, even if massless, may exhibit flavor oscillations.
+Velocity differences far smaller than any previously probed can produce
+characteristic effects at accelerators and solar neutrino experiments.",9703240v3
+1997-10-07,Cosmological implications of neutrinos,"Massive neutrinos were the first proposed, and remain the most natural,
+particle candidate for the dark matter. In the absence of firm laboratory
+evidence for neutrino mass, considerations of the formation of large scale
+structure in the universe provide a sensitive, albeit indirect, probe of this
+possibility. Observations of galaxy clustering and large angle anisotropy in
+the cosmic microwave background have been interpreted as requiring that
+neutrinos provide about 20% of the critical density. However the need for such
+`hot' dark matter is removed if the primordial spectrum of density fluctuations
+is tilted below scale-invariance, as is often the case in physically realistic
+inflationary models. This question will be resolved by forthcoming precision
+measurements of microwave background anisotropy on small angular scales. This
+data will also improve the nucleosynthesis bound on the number of neutrino
+species and test whether decays of relic neutrinos could have ionized the
+intergalactic medium.",9710273v2
+1998-06-09,Constraints on pre-big bang models for seeding large-scale anisotropy by massive Kalb-Ramond axions,"We discuss the conditions under which pre-big bang models can fit the
+observed large-scale anisotropy with a primordial spectrum of massive
+(Kalb--Ramond) axion fluctuations.
+  The primordial spectrum must be sufficiently flat at low frequency and
+sufficiently steeper at high frequency. For a steep and/or long enough
+high-frequency branch of the spectrum the bounds imposed by COBE's
+normalization allow axion masses of the typical order for a
+Peccei--Quinn--Weinberg--Wilczek axion. We provide a particular example in
+which an appropriate axion spectrum is obtained from a class of backgrounds
+satisfying the low-energy string cosmology equations.",9806327v1
+1999-12-15,Cosmological measurement of neutrino mass in the presence of leptonic asymmetry,"We show that even the smallest neutrino mass consistent with the
+Super--Kamiokande data is relevant for cosmological models of structure
+formation and cosmic microwave background (CMB) anisotropies, provided that a
+relic neutrino asymmetry exists. We calculate the precision with which a 0.07
+eV neutrino mass could be extracted from CMB anisotropy and large-scale
+structure data by the future Planck satellite and Sloan Digital Sky Survey. We
+find that such a mass can be detected, assuming a large relic neutrino
+asymmetry still allowed by current experimental data. This measurement of the
+absolute value of the neutrino mass would be crucial for our understanding of
+neutrino models.",9912363v2
+2001-10-07,Effects of Cosmological Moduli Fields on Cosmic Microwave Background,"We discuss effects of cosmological moduli fields on the cosmic microwave
+background (CMB). If a modulus field \phi once dominates the universe, the CMB
+we observe today is from the decay of \phi and its anisotropy is affected by
+the primordial fluctuation in the amplitude of the modulus field. Consequently,
+constraints on the inflaton potential from the CMB anisotropy can be relaxed.
+In particular, the scale of the inflation may be significantly lowered. In
+addition, with the cosmological moduli fields, correlated mixture of adiabatic
+and isocurvature fluctuations may be generated, which results in enhanced CMB
+angular power spectrum at higher multipoles relative to that of lower ones.
+Such an enhancement can be an evidence of the cosmological moduli fields, and
+may be observed in future satellite experiments.",0110096v3
+2002-10-29,Cosmic Microwave Background from Late-Decaying Scalar Condensations,"We study the cosmic microwave background (CMB) anisotropy in the scenario
+with late-decaying scalar condensations which arise in many class of
+cosmological scenarios based on supersymmetric models. With such a scalar
+condensation \phi, the CMB radiation we observe today originates to \phi and
+hence the CMB anisotropy is affected if \phi has a primordial fluctuation. In
+particular, if all the components in the universe (i.e., radiation, baryon,
+cold dark matter, and so on) are generated from the decay product of \phi, the
+dominant source of the cosmic density perturbations can be the primordial
+fluctuation of \phi, not the fluctuation of the inflaton field. In this case,
+the constraints on the inflation models can be drastically relaxed. In other
+case, the baryon or the CDM may not be from the decay product of \phi and
+correlated mixture of the adiabatic and isocurvature fluctuations can be
+generated. If so, the CMB angular power spectrum may not be the same as the
+adiabatic result and the on-going MAP experiment may observe a deviation from
+the prediction of the standard inflationary scenario.",0210392v1
+2002-11-02,CMB Anisotropy from Baryogenesis by a Scalar Field,"We study the cosmic microwave background (CMB) anisotropy in the scenario
+where the baryon asymmetry of the universe is generated from a condensation of
+a scalar field. In such a scenario, the scalar condensation may acquire
+fluctuation during the inflation which becomes a new source of the cosmic
+density perturbations. In particular, the primordial fluctuation of the scalar
+condensation may induce correlated mixture of the adiabatic and isocurvature
+fluctuations. If the scalar condensation decays before it completely dominates
+the universe, the CMB angular power spectrum may significantly deviate from the
+conventional adiabatic result. Such a deviation may be observed in the on-going
+MAP experiment.",0211019v1
+2002-12-08,Constraints on pre-big bang parameter space from CMBR anisotropies,"The so-called curvaton mechanism --a way to convert isocurvature
+perturbations into adiabatic ones-- is investigated both analytically and
+numerically in a pre-big bang scenario where the role of the curvaton is played
+by a sufficiently massive Kalb--Ramond axion of superstring theory. When
+combined with observations of CMBR anisotropies at large and moderate angular
+scales, the present analysis allows us to constrain quite considerably the
+parameter space of the model: in particular, the initial displacement of the
+axion from the minimum of its potential and the rate of evolution of the
+compactification volume during pre-big bang inflation. The combination of
+theoretical and experimental constraints favours a slightly blue spectrum of
+scalar perturbations, and/or a value of the string scale in the vicinity of the
+SUSY-GUT scale.",0212112v1
+2003-04-14,Cosmic String from D-term Inflation and Curvaton,"We study effects of the cosmic string in the D-term inflation model on the
+cosmic microwave background (CMB) anisotropy. In the D-term inflation model,
+gauged cosmic string is usually formed, which may significantly affect the CMB
+anisotropy. We see that its study imposes important constraint. In order to
+realize the minimal model of D-term inflation, we see that the coupling
+constant \lambda in the superpotential generating the inflaton potential should
+be significantly small, \lambda \lesssim O(10^{-4}-10^{-5}). We also discuss
+that a consistent scenario of the D-term inflation with \lambda \sim 1 can be
+constructed by adopting the curvaton mechanism where the cosmic density
+fluctuations are generated by a primordial fluctuation of a late-decaying
+scalar field other than the inflaton.",0304126v1
+2003-12-11,Quasiparticle description of the hot and dense quark-gluon plasma,"The collective modes of QCD at temperatures and densities above its
+phase-transition are analyzed for isotropic systems as well as for systems
+having an anisotropy in momentum-space using the HTL approximation. For
+isotropic systems, results for the thermodynamic pressure and entropy at finite
+densities based on a phenomenological description of lattice calculations at
+vanishing densities are derived and compared to those following from different
+methods. From the resulting equation of state the mass-radius relationship of
+so-called quark-stars and other applications are investigated. It is shown that
+systems with anisotropic momentum-space distributions contain unstable modes in
+addition to the stable quasiparticle modes, which may be of great importance
+for the dynamical evolution of an incompletely thermalized quark-gluon plasma.
+Finally, the effects of the anisotropy on the collisional energy loss are
+studied.",0312152v2
+2004-03-20,Does the Low CMB Quadrupole Provide a New Cosmic Coincidence Problem ?,"We point out that the recent WMAP findings of a suppressed large scale power
+in the Cosmic Microwave Background anisotropy power spectrum, if of
+cosmological origin, make the case for a new cosmic coincidence problem.The
+observed suppression of anisotropies at large angles requires an explanation
+for why this suppression is occuring {\it only} for perturbation wavelengths of
+the order of our present Hubble horizon. This is a very challenging task since
+a consistent model for the emerging picture of the universe has to address any
+cosmic coincidence and thus may reveal a deeper inter-relation with the dark
+energy problem.",0403222v1
+2005-05-30,From Primordial Quantum Fluctuations to the Anisotropies of the Cosmic Microwave Background Radiation,"These lecture notes cover mainly three connected topics. In the first part we
+give a detailed treatment of cosmological perturbation theory. The second part
+is devoted to cosmological inflation and the generation of primordial
+fluctuations. In part three it will be shown how these initial perturbation
+evolve and produce the temperature anisotropies of the cosmic microwave
+background radiation. Comparing the theoretical prediction for the angular
+power spectrum with the increasingly accurate observations provides important
+cosmological information (cosmological parameters, initial conditions).",0505249v3
+2005-05-31,Dynamics of Quark-Gluon-Plasma Instabilities in Discretized Hard-Loop Approximation,"Non-Abelian plasma instabilities have been proposed as a possible explanation
+for fast isotropization of the quark-gluon plasma produced in relativistic
+heavy-ion collisions. We study the real-time evolution of these instabilities
+in non-Abelian plasmas with a momentum-space anisotropy using a hard-loop
+effective theory that is discretized in the velocities of hard particles. We
+extend our previous results on the evolution of the most unstable modes, which
+are constant in directions transverse to the direction of anisotropy, from
+gauge group SU(2) to SU(3). We also present first full 3+1-dimensional
+simulation results based on velocity-discretized hard loops. In contrast to the
+effectively 1+1-dimensional transversely constant modes we find subexponential
+behaviour at late times.",0505261v3
+2005-08-18,Azimuthal Asymmetry of Direct Photons in High Energy Nuclear Collisions,"We show that a sizeable azimuthal asymmetry, characterized by a coefficient
+v_2, is to be expected for direct photons produced in non-central high energy
+nuclear collisions. This signal is generated by photons radiated by jets
+interacting with the surrounding hot plasma. The anisotropy is out of phase by
+an angle $\pi/2$ with respect to that associated with the elliptic anisotropy
+of hadrons, leading to negative values of v_2. Such an asymmetry, if observed,
+could be a signature for the presence of a quark gluon plasma and would
+establish the importance of jet-plasma interactions as a source of
+electromagnetic radiation.",0508201v3
+2006-03-03,A model of the effect of collisions on QCD plasma instabilities,"We study the effect of including a BGK collisional kernel on the collective
+modes of a QCD plasma which has a hard-particle distribution function which is
+anisotropic in momentum space. We calculate dispersion relations for both the
+stable and unstable modes and show that the addition of hard particle
+collisions slows the rate of growth of QCD plasma unstable modes. We also show
+that for any anisotropy there is an upper limit on the collisional frequency
+beyond which no instabilities exist. Estimating a realistic value for the
+collisional frequency for alpha_s ~ 0.2 - 0.4 we find that for the
+large-anisotropy case which is relevant for the initial state of matter
+generated by free streaming in heavy-ion collisions that the collisional
+frequency is below this critical value.",0603029v1
+2006-06-28,Implications of cosmic strings with time-varying tension on CMB and large scale structure,"We investigate cosmological evolution and implications of cosmic strings with
+time-dependent tension. We derive basic equations of time development of the
+correlation length and the velocity of such strings, based on the one scale
+model. Then, we find that, in the case where the tension depends on some power
+of the cosmic time, cosmic strings with time-dependent tension goes into the
+scaling solution if the power is lower than a critical value. We also discuss
+cosmic microwave background anisotropy and matter power spectra produced by
+these strings. The constraints on their tensions from the Wilkinson microwave
+anisotropy probe (WMAP) three year data and Sloan digital sky survey (SDSS)
+data are also given.",0606287v1
+2006-07-20,Can a vector field be responsible for the curvature perturbation in the Universe?,"I investigate the possibility that the observed curvature perturbation is due
+to a massive vector field. To avoid generating a large scale anisotropy the
+vector field is not taken to be driving inflation. Instead it is assumed to
+become important after inflation when it may dominate the Universe and imprint
+its perturbation spectrum before its decay, as in the curvaton scenario. It is
+found that, to generate a scale invariant spectrum of perturbations, the
+mass-squared of the vector field has to be negative and comparable to the
+Hubble scale during inflation. After inflation the mass-squared must become
+positive so that the vector field engages into oscillations. It is shown that,
+such an oscillating vector field behaves as pressureless matter and does not
+lead to large scale anisotropy when it dominates the Universe. The possibilitiy
+of realising this scenario in supergravity is also outlined.",0607229v2
+1993-02-01,Spin-Anisotropy Commensurable Chains: Quantum Group Symmetries and N=2 SUSY,"In this paper we consider a class of the 2D integrable models. These models
+are higher spin XXZ chains with an extra condition of the commensurability
+between spin and anisotropy. The mathematics underlying this commensurability
+is provided by the quantum groups with deformation parameter being an Nth root
+of unity. Our discussion covers a range of topics including new integrable
+deformations, thermodynamics, conformal behaviour, S-matrices and
+magnetization. The emerging picture strongly depends on the N-parity. For the N
+even case at the commensurable point, S-matrices factorize into N=2
+supersymmetric Sine-Gordon matrix and an RSOS piece. The physics of the N odd
+case is rather different. Here, the supersymmetry does not manifest itself and
+the bootstrap hypothesis fails. Away from the commensurable point, we find an
+unusual behaviour. The magnetization of our chains depends on the sign of the
+external magnetic field.",9302001v1
+1994-07-13,The Dynamical Correlation Function of the XXZ Model,"We perform a spectral decomposition of the dynamical correlation function of
+the spin $1/2$ XXZ model into an infinite sum of products of form factors.
+Beneath the four-particle threshold in momentum space the only non-zero
+contributions to this sum are the two-particle term and the trivial vacuum
+term. We calculate the two-particle term by making use of the integral
+expressions for form factors provided recently by the Kyoto school. We evaluate
+the necessary integrals by expanding to twelfth order in $q$. We show plots of
+$S(w,k)$, for $k=0$ and $\pi$ at various values of the anisotropy parameter,
+and for fixed anisotropy at various $k$ around $0$ and $\pi$.",9407062v1
+2001-10-30,"Ellipsoidal, Cylindrical, Bipolar and Toroidal Wormholes in 5D Gravity","In this paper we construct and analyze new classes of wormhole and flux
+tube-like solutions for the 5D vacuum Einstein equations. These 5D solutions
+possess generic local anisotropy which gives rise to a gravitational running or
+scaling of the Kaluza-Klein ``electric'' and ``magnetic'' charges of these
+solutions. It is also shown that it is possible to self-consistently construct
+these anisotropic solutions with various rotational 3D hypersurface geometries
+(i.e. ellipsoidal, cylindrical, bipolar and toroidal). The local anisotropy of
+these solutions is handled using the technique of anholonomic frames with their
+associated nonlinear connection structures [vst]. Through the use of the
+anholonomic frames the metrics are diagonalized, in contrast to holonomic
+coordinate frames where the metrics would have off-diagonal components. In the
+local isotropic limit these solutions are shown to be equivalent to spherically
+symmetric 5D wormhole and flux tube solutions.",0110272v2
+2002-04-08,Cosmic String Production Towards the End of Brane Inflation,"Towards the end of the brane inflationary epoch in the brane world, cosmic
+strings (but not texture, domain walls or monopoles) are copiously produced
+during brane collision. These cosmic strings are D$p$-branes with $(p-1)$
+dimensions compactified. We elaborate on this prediction of the superstring
+theory description of the brane world. Using the data on the temperature
+anisotropy in the cosmic microwave background, we estimate the cosmic string
+tension $\mu$ to be around $G \mu \simeq 10^{-7}$. This in turn implies that
+the anisotropy in the cosmic microwave background comes mostly from inflation,
+but with a component (of order 10%) from cosmic strings. This cosmic string
+effect should also be observable in gravitational wave detectors and maybe even
+pulsar timing measurements.
+  Keywords : Inflation, Brane World, Superstring Theory, Cosmic String,
+Cosmology",0204074v1
+2002-05-06,Inflationary cosmology in the central region of String/M-theory moduli space,"The ""central"" region of moduli space of M- and string theories is where the
+string coupling is about unity and the volume of compact dimensions is about
+the string volume. Here we argue that in this region the non-perturbative
+potential which is suggested by membrane instanton effects has the correct
+scaling and shape to allow for enough slow-roll inflation, and to produce the
+correct amplitude of CMB anisotropies. Thus, the well known theoretical
+obstacles for achieving viable slow-roll inflation in the framework of
+perturbative string theory are overcome. Limited knowledge of some generic
+properties of the induced potential is sufficient to determine the simplest
+type of consistent inflationary model and its predictions about the spectrum of
+cosmic microwave background anisotropies: a red spectrum of scalar
+perturbations, and negligible amount of tensor perturbations.",0205042v1
+2002-07-18,Isotropization in Brane Gas Cosmology,"Brane Gas Cosmology (BGC) is an approach to unifying string theory and
+cosmology in which matter is described by a gas of strings and branes in a
+dilaton gravity background. The Universe is assumed to start out with all
+spatial dimensions compact and small. It has previously been shown that in this
+context, in the approximation of neglecting inhomogeneities and anisotropies,
+there is a dynamical mechanism which allows only three spatial dimensions to
+become large. However, previous studies do not lead to any conclusions
+concerning the isotropy or anisotropy of these three large spatial dimensions.
+Here, we generalize the equations of BGC to the anisotropic case, and find that
+isotropization is a natural consequence of the dynamics.",0207168v3
+2002-11-08,(Non)Commutative Finsler Geometry from String/M--theory,"We synthesize and extend the previous ideas about appearance of both
+noncommutative and Finsler geometry in string theory with nonvanishing B--field
+and/or anholonomic (super) frame structures \cite{vstring,vstr2,vnonc,vncf}.
+There are investigated the limits to the Einstein gravity and string
+generalizations containing locally anisotropic structures modeled by moving
+frames. The relation of anholonomic frames and nonlinear connection geometry to
+M--theory and possible noncommutative versions of locally anisotropic
+supergravity and D--brane physics is discussed. We construct and analyze new
+classes of exact solutions with noncommutative local anisotropy describing
+anholonomically deformed black holes (black ellipsoids) in string gravity,
+embedded Finsler--string two dimensional structures, solitonically moving black
+holes in extra dimensions and wormholes with noncommutativity and anisotropy
+induced from string theory.",0211068v3
+2003-07-02,Primeval Corrections to the CMB Anisotropies,"We show that deviations of the quantum state of the inflaton from the thermal
+vacuum of inflation may leave an imprint in the CMB anisotropies. The quantum
+dynamics of the inflaton in such a state produces corrections to the
+inflationary fluctuations, which may be observable. Because these effects
+originate from IR physics below the Planck scale, they will dominate over any
+trans-Planckian imprints in any theory which obeys decoupling. Inflation sweeps
+away these initial deviations and forces its quantum state closer to the
+thermal vacuum. We view this as the quantum version of the cosmic no-hair
+theorem. Such imprints in the CMB may be a useful, independent test of the
+duration of inflation, or of significant features in the inflaton potential
+about 60 e-folds before inflation ended, instead of an unlikely discovery of
+the signatures of quantum gravity. The absence of any such substructure would
+suggest that inflation lasted uninterrupted much longer than ${\cal O}(100)$
+e-folds.",0307016v3
+2003-07-10,CMB anisotropies from vector perturbations in the bulk,"The vector perturbations induced on the brane by gravitational waves
+propagating in the bulk are studied in a cosmological framework. Cosmic
+expansion arises from the brane motion in a non-compact five-dimensional
+anti-de Sitter spacetime. By solving the vector perturbation equations in the
+bulk, for generic initial conditions, we find that they give rise to growing
+modes on the brane in the Friedmann-Lema\^{\i}tre era. Among these modes, we
+exhibit a class of normalizable perturbations, which are exponentially growing
+with respect to conformal time on the brane. The presence of these modes is, at
+least, strongly constrained by the current observations of the cosmic microwave
+background (CMB). We estimate the anisotropies they induce in the CMB, and
+derive quantitative constraints on the allowed amplitude of their primordial
+spectrum. Our results provide stringent constraints for all braneworld models
+with bulk inflation.",0307100v1
+2003-12-28,A mechanism of the large-scale damping in the CMB anisotropy,"We present a mechanism through which a certain class of short-distance cutoff
+affects the CMB anisotropies at large angular scales. Our analysis is performed
+in two steps. The first is given in an intuitive way, using the property of the
+inflationary universe that quantum fluctuations of an inflaton field become
+classical after crossing the Hubble horizon. We give a condition for a cutoff
+to yield a damping on large scales, and show that the holographic cutoff
+introduced in the preceding paper (hep-th/0307029) does satisfy the condition.
+The second analysis is carried out by setting an initial condition such that
+each mode of inflaton starts as the vacuum fluctuation of the Hamiltonian when
+being released from the constraint of cutoff. The first intuitive discussion is
+then shown to be correct qualitatively.",0312298v7
+2005-07-01,3+1 Approach to the Long Wavelength Iteration Scheme,"Large-scale inhomogeneities and anisotropies are modeled using the Long
+Wavelength Iteration Scheme. In this scheme solutions are obtained as
+expansions in spatial gradients, which are taken to be small. It is shown that
+the choice of foliation for spacetime can make the iteration scheme more
+effective in two respects: (i) the shift vector can be chosen so as to dilute
+the effect of anisotropy on the late-time value of the extrinsic curvature of
+the spacelike hypersurfaces of the foliation; and (ii) pure gauge solutions
+present in a similar calculation using the synchronous gauge vanish when the
+spacelike hypersurfaces have extrinsic curvature with constant trace. We
+furthermore verify the main conclusion of the synchronous gauge calculation
+which is large-scale inhomogeneity decays if the matter--considered to be that
+of a perfect-fluid with a barotropic equation of state--violates the
+strong-energy condition. Finally, we obtain the solution for the lapse function
+and discuss its late-time behaviour. It is found that the lapse function is
+well-behaved when the matter violates the strong energy condition.",0507015v1
+2006-05-04,Scaling Dynamics of Domain Walls in the Cubic Anisotropy Model,"We have investigated the dynamics of domain walls in the cubic anisotropy
+model. In this model a global O(N) symmetry is broken to a set of discrete
+vacua either on the faces, or vertices of a (hyper)cube. We compute the scaling
+exponents for $2\le N\le 7$ in two dimensions on grids of $2048^2$ points and
+compare them to the fiducial model of $Z_2$ symmetry breaking. Since the model
+allows for wall junctions lattice structures are locally stable and
+modifications to the standard scaling law are possible. However, we find that
+since there is no scale which sets the distance between walls, the walls appear
+to evolve toward a self-similar regime with $L\sim t$.",0605057v1
+2006-07-27,D-term inflation in non-minimal supergravity,"D-term inflation is one of the most interesting and versatile models of
+inflation. It is possible to implement naturally D-term inflation within high
+energy physics, as for example SUSY GUTs, SUGRA, or string theories. D-term
+inflation avoids the $\eta$-problem, while in its standard form it always ends
+with the formation of cosmic strings. Given the recent three-year WMAP data on
+the cosmic microwave background temperature anisotropies, we examine whether
+D-term inflation can be successfully implemented in non-minimal supergravity
+theories. We show that for all our choices of K\""ahler potential, there exists
+a parameter space for which the predictions of D-term inflation are in
+agreement with the measurements. The cosmic string contribution on the measured
+temperature anisotropies is always dominant, unless the superpotential coupling
+constant is fine tuned; a result already obtained for D-term inflation within
+minimal supergravity. In conclusion, cosmic strings and their r\^ole in the
+angular power spectrum cannot be easily hidden by just considering a non-flat
+K\""ahler geometry.",0607226v2
+2006-11-07,Making a Universe,"For understanding the origin of anisotropies in the cosmic microwave
+background, rules to construct a quantized universe is proposed based on the
+dynamical triangulation method of the simplicial quantum gravity. A
+$d$-dimensional universe having the topology $ D^d $ is created numerically in
+terms of a simplicial manifold with $d$-simplices as the building blocks. The
+space coordinates of a universe are identified on the boundary surface $
+S^{d-1} $, and the time coordinate is defined along the direction perpendicular
+to $ S^{d-1} $. Numerical simulations are made mainly for 2-dimensional
+universes, and analyzed to examine appropriateness of the construction rules by
+comparing to analytic results of the matrix model and the Liouville theory.
+Furthermore, a simulation in 4-dimension is made, and the result suggests an
+ability to analyze the observations on anisotropies by comparing to the scalar
+curvature correlation of a $ S^2 $-surface formed as the last scattering
+surface in the $ S^3 $ universe.",0611076v2
+1998-12-18,Growth Rates in the Quaquaversal Tiling,"Conway and Radin's ""quaquaversal"" tiling of R^3 is known to exhibit
+statistical rotational symmetry in the infinite volume limit. A finite patch,
+however, cannot be perfectly isotropic, and we compute the rates at which the
+anisotropy scales with size. In a sample of volume N, tiles appear in
+O(N^{1/6}) distinct orientations. However, the orientations are not uniformly
+populated. A small (O(N^{1/84})) set of these orientations account for the
+majority of the tiles. Furthermore, these orientations are not uniformly
+distributed on SO(3). Sample averages of functions on SO(3) seem to approach
+their ergodic limits as N^{-1/336}. Since even macroscopic patches of a
+quaquaversal tiling maintain noticable anisotropy, a hypothetical physical
+quasicrystal whose structure was similar to the quaquaversal tiling could be
+identified by anisotropic features of its electron diffraction pattern.",9812018v2
+2001-03-20,Staggered Anisotropy Parameter Modification of the Anisotropic $t-J$ Model,"The anisotropic t-J model ($U_q(gl(2|1))$ Perk-Schultz model) with staggered
+disposition of the anisotropy parameter along a chain is considered and the
+corresponding ladder type integrable model is constructed. This is a
+generalisation to spin-1 case of the staggered $XXZ$ spin-1/2 model considered
+earlier. The corresponding Hamiltonian is calculated and, since it contains
+next to nearest neighbour interaction terms, can be written in a zig-zag form.
+The Algebraic Bethe Ansatz technique is applied and the eigenstates, along with
+eigenvalues of the transfer matrix of the model are found.",0103027v3
+2002-07-05,Scaling Exponents in Anisotropic Hydrodynamic Turbulence,"In anisotropic turbulence the correlation functions are decomposed in the
+irreducible representations of the SO(3) symmetry group (with different
+""angular momenta"" $\ell$). For different values of $\ell$ the second order
+correlation function is characterized by different scaling exponents
+$\zeta_2(\ell)$. In this paper we compute these scaling exponents in a Direct
+Interaction Approximation (DIA). By linearizing the DIA equations in small
+anisotropy we set up a linear operator and find its zero-modes in the inertial
+interval of scales. Thus the scaling exponents in each $\ell$-sector follow
+from solvability condition, and are not determined by dimensional analysis. The
+main result of our calculation is that the scaling exponents $\zeta_2(\ell)$
+form a strictly increasing spectrum at least until $\ell=6$, guaranteeing that
+the effects of anisotropy decay as power laws when the scale of observation
+diminishes. The results of our calculations are compared to available
+experiments and simulations.",0207011v2
+2005-01-01,Equatorial and related non-equilibrium states in magnetization dynamics of ferromagnets: Generalization of Suhl's spin-wave instabilities,"We investigate the nonlinear dynamics underlying the evolution of a 2-D
+nanoscale ferromagnetic film with uniaxial anisotropy in the presence of
+perpendicular pumping. Considering the associated Landau-Lifshitz spin
+evolution equation with Gilbert damping together with Maxwell equation for the
+demagnetization field, we study the dynamics in terms of the stereographic
+variable. We identify several new fixed points for suitable choice of external
+field in a rotating frame of reference. In particular, we identify explicit
+equatorial and related fixed points of the spin vector in the plane transverse
+to the anisotropy axis when the pumping frequency coincides with the amplitude
+of the static parallel field. We then study the linear stability of these novel
+fixed points under homogeneous and spin wave perturbations and obtain a
+generalized Suhl's instability criterion, giving the condition for exponential
+growth of P-modes under spin wave perturbations. Two parameter phase diagrams
+(in terms of amplitudes of static parallel and oscillatory perpendicular
+magnetic fields) for stability are obtained, which differ qualitatively from
+those for the conventional ferromagnetic resonance near thermal equilibrium and
+are amenable to experimental tests.",0501002v2
+2006-07-28,Combined effects of small scale anisotropy and compressibility on anomalous scaling of a passive scalar,"Model of a passive scalar field advected by the compressible Gaussian
+strongly anisotropic velocity field with the covariance $\propto
+\delta(t-t^{\prime})|{\bf x}-{\bf x^{\prime}}|^{2\epsilon}$ is studied by using
+the field theoretic renormalization group and the operator product expansion.
+The inertial-range stability of the corresponding scaling regime is
+established. The anomalous scaling of the single-time structure functions is
+studied and the corresponding anomalous exponents are calculated. Their
+dependence on the compressibility parameter and anisotropy parameters is
+analyzed. It is shown that, as in the isotropic case, the presence of
+compressibility leads to the decreasing of the critical dimensions of the
+important composite operators, i.e., the anomalous scaling is more pronounced
+in the compressible systems. All calculations are done to the first order in
+$\epsilon$.",0607066v3
+1997-09-15,Azimuthal Anisotropies as Stringent Test for Nuclear Transport Models,"Azimuthal distributions of charged particles and intermediate mass fragments
+emitted in Au+Au collisions at 600AMeV have been measured using the FOPI
+facility at GSI-Darmstadt. Data show a strong increase of the in-plane
+azimuthal anisotropy ratio with the charge of the detected fragment.
+Intermediate mass fragments are found to exhibit a strong momentum-space
+alignment with respect of the reaction plane. The experimental results are
+presented as a function of the polar center-of-mass angle and over a broad
+range of impact parameters. They are compared to the predictions of the Isospin
+Quantum Molecular Dynamics model using three different parametrisations of the
+equation of state. We show that such highly accurate data provide stringent
+test for microscopic transport models and can potentially constrain separately
+the stiffness of the nuclear equation of state and the momentum dependence of
+the nuclear interaction.",9709004v1
+1999-03-15,Azimuthal Anisotropy of $η$ and $π^{0}$ Mesons in Heavy-Ion Collisions at 2 AGeV,"Azimuthal distributions of $\eta$ and $\pi^{0}$ mesons emitted at midrapidity
+in collisions of 1.9 AGeV $^{58}$Ni+$^{58}$Ni and 2 AGeV $^{40}$Ca+$^{nat}$Ca
+are studied as a function of the number of projectile-like spectator nucleons.
+The observed anisotropy corresponds to a negative elliptic flow signal for
+$\eta$ mesons, indicating a preferred emission perpendicular to the reaction
+plane. The effect is smallest in peripheral Ni+Ni collisions. In contrast, for
+$\pi^{0}$ mesons, elliptic flow is observed only in peripheral Ni+Ni
+collisions, changing from positive to negative sign with increasing pion
+transverse momentum.",9903008v1
+1999-10-05,Elliptic flow of $η$ and $π^{0}$ Mesons in Heavy-Ion Collisions at 2 AGeV,"Azimuthal distributions of $\eta$ and $\pi^{0}$ mesons emitted at midrapidity
+in collisions of 1.9 AGeV $^{58}$Ni+$^{58}$Ni and 2 AGeV $^{40}$Ca+$^{nat}$Ca
+are studied as a function of the number of projectile-like spectator nucleons.
+The observed anisotropy corresponds to a negative elliptic flow signal for
+$\eta$ mesons, indicating a preferred emission perpendicular to the reaction
+plane. In contrast, only small azimuthal anisotropies are observed for
+$\pi^{0}$ mesons. This may indicate that $\eta$ mesons freeze out earlier from
+the fire ball than pions.",9910002v1
+2003-06-04,Particle-type dependence of azimuthal anisotropy and nuclear modification of particle production in Au+Au collisions at s(NN)**(1/2) = 200-GeV,"We present STAR measurements of the azimuthal anisotropy parameter $v_2$ and
+the binary-collision scaled centrality ratio $R_{CP}$ for kaons and lambdas
+($\Lambda+\bar{\Lambda}$) at mid-rapidity in Au+Au collisions at
+$\sqrt{s_{_{NN}}}=200$ GeV. In combination, the $v_2$ and $R_{CP}$
+particle-type dependencies contradict expectations from partonic energy loss
+followed by standard fragmentation in vacuum. We establish $p_T \approx 5$
+GeV/c as the value where the centrality dependent baryon enhancement ends. The
+$K_S^0$ and $\Lambda+\bar{\Lambda}$ $v_2$ values are consistent with
+expectations of constituent-quark-number scaling from models of hadron
+fromation by parton coalescence or recombination.",0306007v3
+2003-06-20,High-p_T charged particle azimuthal correlations at RHIC,"The analysis of two-particle azimuthal correlation function in p+p and Au+Au
+collisions at s(NN)**(1/2) 200 GeV/c is presented. The mean jet fragmentation
+transverse momentum <|mjTy|> and mean parton transverse momentum <|kTy|> are
+inferred from p+p collisions. The analysis of Au+Au data, where elliptic flow
+is a dominant source of two-particles correlation is also presented. We derive
+the upper limit on partonic azimuthal anisotropy based on jet-quenching in a
+Glauber model. We show that some new mechanism, generating the azimuthal
+anisotropy observed in final state, is needed.",0306031v3
+2003-09-22,Statistical Multifragmentation of Non-Spherical Expanding Sources in Central Heavy-Ion Collisions,"We study the anisotropy effects measured with INDRA at GSI in central
+collisions of Xe+Sn at 50 A.MeV and Au+Au at 60, 80, 100 A.MeV incident energy.
+The microcanonical multifragmentation model with non-spherical sources is used
+to simulate an incomplete shape relaxation of the multifragmenting system. This
+model is employed to interpret observed anisotropic distributions in the
+fragment size and mean kinetic energy. The data can be well reproduced if an
+expanding prolate source aligned along the beam direction is assumed. An either
+non-Hubblean or non-isotropic radial expansion is required to describe the
+fragment kinetic energies and their anisotropy. The qualitative similarity of
+the results for the studied reactions suggests that the concept of a
+longitudinally elongated freeze-out configuration is generally applicable for
+central collisions of heavy systems. The deformation decreases slightly with
+increasing beam energy.",0309016v2
+2004-07-09,Azimuthal anisotropy and correlations at large transverse momenta in $p+p$ and Au+Au collisions at $\sqrt{s_{_{NN}}}$= 200 GeV,"Results on high transverse momentum charged particle emission with respect to
+the reaction plane are presented for Au+Au collisions at $\sqrt{s_{_{NN}}}$=
+200 GeV. Two- and four-particle correlations results are presented as well as a
+comparison of azimuthal correlations in Au+Au collisions to those in $p+p$ at
+the same energy. Elliptic anisotropy, $v_2$, is found to reach its maximum at
+$p_t \sim 3$ GeV/c, then decrease slowly and remain significant up to
+$p_t\approx 7$ -- 10 GeV/c. Stronger suppression is found in the back-to-back
+high-$p_t$ particle correlations for particles emitted out-of-plane compared to
+those emitted in-plane. The centrality dependence of $v_2$ at intermediate
+$p_t$ is compared to simple models based on jet quenching.",0407007v3
+2004-12-21,Semihard scattering unraveled from collective dynamics at $\sqrt{s}$=17 GeV,"We present a study of elliptic flow ($v_2$) and two-particle azimuthal
+correlations of charged hadrons and high transverse momentum ($p_T$) pions
+measured by the CERES experiment in Pb+Au collisions at $\sqrt{s}$~=~17 GeV.
+Azimuthal anisotropy $v_2$ increases linearly with $p_T$ to a value of 10% at
+$p_T$~=~1.5 GeV/$c$. Beyond this $p_T$ the slope decreases indicating a
+possible saturation at high $p_T$. Two-pion azimuthal anisotropies ($p_T>$~1.2
+GeV/$c$) exceed $v_2$ by about 60% in semicentral collisions and reveal
+non-harmonic contributions at close ($\Delta\phi\approx0$) and back-to-back
+($\Delta\phi\approx\pi$) angles that can be attributed to semihard processes.
+While the close-angle peak remains unchanged, the back-to-back peak is
+broadened and disappears in central collisions.",0412047v1
+2005-02-04,Measurement of Single Electron Event Anisotropy in Au+Au Collisions at sqrt(s_NN) = 200 GeV,"The transverse momentum dependence of the azimuthal anisotropy parameter v_2,
+the second harmonic of the azimuthal distribution, for electrons at
+mid-rapidity (|eta| < 0.35) has been measured with the PHENIX detector in Au+Au
+collisions at sqrt(s_NN) = 200 GeV. The measurement was made with respect to
+the reaction plane defined at high rapidities (|eta| = 3.1 -- 3.9). From the
+result we have measured the v_2 of electrons from heavy flavor decay after
+subtraction of the v_2 of electrons from other sources such as photon
+conversions and Dalitz decay from light neutral mesons. We observe a non-zero
+single electron v_2 with a 90% confidence level in the intermediate p_T region.",0502009v1
+2005-09-08,Single Electron Transverse Momentum and Azimuthal Anisotropy Distributions: Charm Hadron Production at RHIC,"Quantum Chromodynamics (QCD) is a basic gauge field theory to describe strong
+interactions. Lattice QCD calculations predict a phase transition from hadronic
+matter to a deconfined, locally thermalized Quark-Gluon Plasma (QGP) state at
+high temperature and small baryon density. Plenty of exciting results from RHIC
+experiments in the first three years have demonstrated that a hot dense matter
+with strong collective motion which cannot be described with hadronic degrees
+of freedom was created at RHIC. Charm quarks are believed to be mostly created
+from initial gluon fusion in heavy ion collisions. Since they are massive,
+charm hadrons are proposed to be ideal probes to study the early stage dynamics
+in heavy ion collisions.
+  We provide here an indirect measurement of charm semi-leptonic decay. Single
+electron transverse momentum ($p_T$) distributions from 200 GeV \dAu, \pp
+collisions and 62.4 GeV \AuAu collisions, and single electron azimuthal
+anisotropy ($v_2$) from 62.4 GeV \AuAu collisions are presented. (Abridged)",0509011v1
+2005-10-07,Azimuthal Anisotropy of Identified Hadrons in 200 GeV Au+Au Collisions,"The azimuthal anisotropy parameter v2 has been measured with high statistics
+for identified hadrons in sqrt(s_NN) = 200 GeV Au+Au collisions with the STAR
+experiment. At high transverse momentum (pT) a strong v2 for pi+ + pi- and p +
+pbar is observed. In the intermediate pT region, number-of-constituent-quark
+scaling was tested to high precision. A detailed comparison of v2 for the
+multi-strange hadrons phi, Xi + anti-Xi, and Omega + anti-Omega with other
+particle species substantiates the development of collectivity among partons in
+the early phase of the collisions at RHIC.",0510026v1
+2006-12-07,Polarization and relaxation of radon,"Investigations of the polarization and relaxation of $^{209}$Rn by spin
+exchange with laser optically pumped rubidium are reported. On the order of one
+million atoms per shot were collected in coated and uncoated glass cells.
+Gamma-ray anisotropies were measured as a signal of the alignment (second order
+moment of the polarization) resulting from the combination of polarization and
+quadrupole relaxation at the cell walls. The temperature dependence over the
+range 130$^\circ$C to 220$^\circ$C shows the anisotropies increasing with
+increasing temperature as the ratio of the spin exchange polarization rate to
+the wall relaxation rate increases faster than the rubidium polarization
+decreases. Polarization relaxation rates for coated and uncoated cells are
+presented. In addition, improved limits on the multipole mixing ratios of some
+of the main gamma-ray transitions have been extracted. These results are
+promising for electric dipole moment measurements of octupole-deformed
+$^{223}$Rn and other isotopes, provided sufficient quantities of the rare
+isotopes can be produced.",0612006v1
+1998-11-03,Remnants of Initial Anisotropic High Energy Density Domains in Nucleus-Nucleus Collisions,"Anisotropic high energy density domains may be formed at early stages of
+ultrarelativistic heavy ion collisions, e.g. due to phase transition dynamics
+or non-equilibrium phenomena like (mini-)jets. Here we investigate hadronic
+observables resulting from an initially created anisotropic high energy density
+domain. Based on our studies using a transport model we find that the initial
+anisotropies are reflected in the freeze-out multiplicity distribution of both
+pions and kaons due to secondary hadronic rescattering. The anisotropy appears
+to be stronger for particles at high transverse momenta. The overall kaon
+multiplicity increases with large fluctuations of local energy densities, while
+no change has been found in the pion multiplicity.",9811006v2
+1999-06-24,The physics of the centrality dependence of elliptic flow,"The centrality dependence of elliptic flow and how it is related to the
+physics of expansion of the system created in high energy nuclear collisions is
+discussed. Since in the hydro limit the centrality dependence of elliptic flow
+is mostly defined by the elliptic anisotropy of the overlapping region of the
+colliding nuclei, and in the low density limit by the product of the elliptic
+anisotropy and the multiplicity, we argue that the centrality dependence of
+elliptic flow should be a good indicator of the degree of equilibration reached
+in the reaction. Then we analyze experimental data obtained at AGS and SPS
+energies. The observed difference in the centrality dependence of elliptic flow
+could imply a transition from a hadronic to a partonic nature of the system
+evolution. Finally we exploit the multiplicity dependence of elliptic flow to
+make qualitative predictions for RHIC and LHC.",9906075v3
+2000-07-27,New method for measuring azimuthal distributions in nucleus-nucleus collisions,"The methods currently used to measure azimuthal distributions of particles in
+heavy ion collisions assume that all azimuthal correlations between particles
+result from their correlation with the reaction plane. However, other
+correlations exist, and it is safe to neglect them only if azimuthal
+anisotropies are much larger than 1/sqrt(N), with N the total number of
+particles emitted in the collision. This condition is not satisfied at
+ultrarelativistic energies. We propose a new method, based on a cumulant
+expansion of multiparticle azimuthal correlations, which allows to measure much
+smaller values of azimuthal anisotropies, down to 1/N. It is simple to
+implement and can be used to measure both integrated and differential flow.
+Furthermore, this method automatically eliminates the major systematic errors,
+which are due to azimuthal asymmetries in the detector acceptance.",0007063v3
+2003-05-05,"High-$p_T$ Hadron Spectra, Azimuthal Anisotropy and Back-to-Back Correlations in High-energy Heavy-ion Collisions","The observed suppression of high-$p_T$ hadron spectra, finite azimuthal
+anisotropy, disappearance of jet-like back-to-back correlations, and their
+centrality dependence in $Au+Au$ collisions at RHIC are shown to be
+quantitatively described by jet quenching within a pQCD parton model. The
+difference between $h^{\pm}$ and $\pi^0$ suppression in intermediate $p_T$ is
+consistent with the observed $(K+p)/\pi$ enhancement which should disappear at
+$p_T>6$ GeV/$c$. The suppression of back-to-back correlations is shown to be
+directly related to the medium modification of jet fragmentation functions(FF).",0305010v4
+2004-11-25,Spin Alignment of Vector Mesons in Non-central A+A Collisions,"We discuss the consequence of global polarization of the produced quarks in
+non-central heavy-ion collisions on the spin alignment of vector mesons. We
+show that the alignment is quite different for different hadronization
+scenarios. These results can be tested directly by measuring the vector mesons'
+alignment through angular distributions of the decay products with respect to
+the reaction plane. Such angular distributions will give rise to azimuthal
+anisotropy $v_2$ of the decay products in the collision frame. Constraints
+provided by the data on the azimuthal anisotropy of hadron spectra at RHIC
+points to a quark recombination scenario of hadronization.",0411101v2
+2005-05-12,Anisotropy of flow and the order of phase transition in relativistic heavy ion collisions,"Using a hydrodynamical model we study how the order of phase transition in
+the equation of state of strongly interacting matter affects single particle
+spectra, elliptic flow and higher order anisotropies in Au+Au collisions at
+RHIC (sqrt{s_NN}=200 GeV energy). We find that the single particle spectra are
+independent of the order of phase transition and that the fourth harmonic
+v_4(p_T) shows only a weak dependence in the p_T region where hydrodynamics is
+expected to work. The differential elliptic flow, v_2(p_T), of baryons shows
+the strongest dependence on equation of state. Surprisingly the closest fit to
+data was obtained when the equation of state had a strong first order phase
+transition and a lattice inspired equation of state fits the data as badly as a
+purely hadronic equation of state.",0505036v2
+2005-11-28,Elliptic flow of thermal photons in relativistic nuclear collisions,"We predict the transverse momentum (pT) dependence of elliptic flow of
+thermal photons for Au+Au collisions at the Relativistic Heavy Ion Collider. We
+model the system hydrodynamically, assuming formation of a thermalized
+quark-gluon plasma at some early time, followed by cooling through expansion,
+hadronization and decoupling. Photons are emitted throughout the expansion
+history. Contrary to hadron elliptic flow, which hydrodynamics predicts to
+increase monotonically with pT, the elliptic flow of thermal photons is
+predicted to first rise and then fall again as pT increases. Photon elliptic
+flow at high pT is shown to reflect the quark momentum anisotropy at early
+times when it is small, whereas at low pT it is controlled by the much larger
+pion momentum anisotropy during the late hadronic emission stage. An
+interesting structure is predicted at intermediate pT ~ 0.4 GeV/c where photon
+elliptic flow reflects the momenta and the (compared to pions) reduced v2 of
+heavy vector mesons in the late hadronic phase.",0511079v2
+1998-09-20,Parametrically forced sine-Gordon equation and domain walls dynamics in ferromagnets,"A parametrically forced sine-Gordon equation with a fast periodic {\em
+mean-zero} forcing is considered. It is shown that $\pi$-kinks represent a
+class of solitary-wave solutions of the equation. This result is applied to
+quasi-one-dimensional ferromagnets with an easy plane anisotropy, in a rapidly
+oscillating magnetic field. In this case the $\pi$-kink solution we have
+introduced corresponds to the uniform ``true'' domain wall motion, since the
+magnetization directions on opposite sides of the wall are anti-parallel. In
+contrast to previous work, no additional anisotropy is required to obtain a
+true domain wall. Numerical simulations showed good qualitative agreement with
+the theory.",9809008v1
+2000-04-28,"The Exchange-correlation Hole of the Si Atom, A Quantum Monte Carlo Study","We have studied the exchange-correlation hole and pair correlation function
+in the valence shell of the ground-state of the Si atom, using accurate
+Slater-Jastrow wavefunctions and the Variational Monte Carlo method. The
+exchange-correlation hole shows a number of interesting features caused by the
+open shell structure of Si, including a marked transition from efficient to
+poor screening behavior as a test majority-spin electron is moved from the
+center of a valence 3p orbital onto the axis perpendicular to the occupied 3p
+orbitals. This behavior results from the dramatic difference in the exchange
+hole in the two cases, which is partially compensated by a corresponding
+anisotropy in the correlation hole. In addition we observe an anisotropic
+change in the spin density induced by Coulomb correlation, reducing the spatial
+overlap between the different spin-components of the density and contributing
+to the anisotropy of the correlation hole. In contrast to the longer range
+features, we find that the ""on-top"" correlation hole is well described by
+linear density functional theory, for a large range of local density and
+magnetization.",0004073v1
+2000-09-04,Test of Cosmic Spatial Isotropy for Polarized Electrons Using a Rotatable Torsion Balance,"To test the cosmic spatial isotropy, we use a rotatable torsion balance
+carrying a transversely spin-polarized ferrimagnetic Dy_{6}Fe_{23} mass. With a
+rotation period of one hour, the period of anisotropy signal is reduced from
+one sidereal day by about 24 times, and hence the 1/f noise is greatly reduced.
+Our present experimental results constrain the cosmic anisotropy Hamiltonian H
+= C_{1} sigma_{1} + C_{2} sigma_{2} + C_{3} sigma_{3} (sigma_{3} is in the axis
+of earth rotation) to (C_{1}^{2} +C_{2}^{2})^{1/2} = (1.8 +- 5.3) X 10^{-21} eV
+and | C_{3} | = (1.2 +- 3.5) X 10^{-19} eV. This improves the previous limits
+on (C_{1},C_{2}) by 120 times and C_{3} by a factor of 800.",0009012v1
+2000-09-13,Average observed properties of the Earth's quasi-perpendicular and quasi-parallel bow shock,"We present a statistical analysis of 132 dayside (LT 0700-1700) bow shock
+crossings of the AMPTE/IRM spacecraft. We perform a superposed epoch analysis
+of plasma and magnetic field parameters as well as of low frequency magnetic
+power spectra some minutes upstream and downstream of the bow shock by dividing
+the events into categories depending on the angle between bow shock normal and
+interplanetary magnetic field and on the plasma-beta, i.e., the ratio of plasma
+to magnetic pressure.
+  Downstream of the quasi-perpendicular low-beta (beta < 0.5) bow shock we find
+a dominance of the left-hand polarized component at frequencies just below the
+ion cyclotron frequency with amplitudes of about 3 nT. These waves are
+identified as ion cyclotron waves which grow in a low-beta regime due to the
+proton temperature anisotropy. We find a strong correlation of this anisotropy
+with the intensity of the left-hand polarized component. Downstream of some
+nearly perpendicular high-beta (beta > 1.0) crossings mirror waves are
+identified. However, there are also cases where the conditions for mirror modes
+are met downstream of the nearly perpendicular shock, but no mirror waves are
+observed.",0009046v1
+2001-01-29,An Atomic Linear Stark Shift Violating P But Not T Arising From the Electroweak Nuclear Anapole Moment,"We propose a direct method of detection of the nuclear anapole moment. It is
+based on the existence of a linear Stark shift for alkali atoms in their ground
+state perturbed by a quadrupolar interaction potential and a magnetic field.
+This shift is proportional to the T-even pseudoscalar built from the
+quadrupolar potential symmetry axis, the directions of the applied electric and
+magnetic fields.It involves on the one hand the anisotropy of the hyperfine
+interaction induced by the quadrupolar interaction and, on the other,the static
+electric dipole moment arising from electroweak interactions inside the
+nucleus. The case of ground state cesium atoms trapped in a uniaxial (hcp)
+phase of solid helium-4 is examined. From an explicit evaluation of both the
+hyperfine structure anisotropy and the static P-odd T-even dipole deduced from
+recent empirical data about the cesium nuclear anapole moment, we predict the
+Stark shift. It is three times the experimental upper bound to be set on the
+T-odd Stark shift of free cesium atoms in order to improve the present limit on
+the electron EDM.",0101098v1
+2001-02-28,Experimental investigations of spatial distribution anisotropy of pulsed plasma generator radiation,"Results of experimental investigation of plasma luminous emittance
+(integrated with respect to time and quartz transmission band spectrum) of a
+pulsed plasma generator depending on its axis spatial position, are presented.
+It is shown that the spatial distribution of plasma radiant intensity is of
+clearly anisotropic character, that is, there exists a cone of the plasma
+generator axial directions in which the radiation of plasma reaches its peak. A
+possible explanation of the results obtained is given based on a hypothesis of
+global anisotropy of space caused by the existence of a cosmological vectorial
+potential $\bf{A}_g$. It is shown that the vector $\bf{A}_g$ has the following
+coordinates in the second equatorial coordinate system: right ascension $\alpha
+= 293^\circ \pm 10^\circ$, declination $\delta = 36^\circ \pm 10^\circ$. The
+experimental results are in accordance with those of the earlier experiments on
+determining the direction of $\bf{A}_g$.",0102090v1
+2001-11-05,Evolution of induced axial magnetization in a two-component magnetized plasma,"In this paper, the evolution of the induced axial magnetization due to the
+propagation of an electromagnetic (em) wave along the static background
+magnetic field in a two-component plasma has been investigated using the Block
+equation. The evolution process induces a strong magnetic anisotropy in the
+plasma medium, depending nonlinearly on the incident wave amplitude. This
+induced magnetic anisotropy can modify the dispersion relation of the incident
+em wave, which has been obtained in this paper. In the low frequency Alfven
+wave limit, this dispersion relation shows that the resulting phase velocity of
+the incident wave depends on the square of the incident wave amplitude and on
+the static background magnetic field of plasma. The analytical results are in
+well agreement with the numerically estimated values in solar corona and
+sunspots.",0111011v1
+2002-04-18,Physical Properties of Iron in the Inner Core,"The Earth's inner core plays a vital role in the dynamics of our planet and
+is itself strongly exposed to dynamic processes as evidenced by a complex
+pattern of elastic structure. To gain deeper insight into the nature of these
+processes we rely on a characterization of the physical properties of the inner
+core which are governed by the material physics of its main constituent, iron.
+Here we review recent research on structure and dynamics of the inner core,
+focusing on advances in mineral physics. We will discuss results on core
+composition, crystalline structure, temperature,and various aspects of
+elasticity. Based on recent computational results, we will show that aggregate
+seismic properties of the inner core can be explained by temperature and
+compression effects on the elasticity of pure iron, and use single crystal
+anisotropy to develop a speculative textural model of the inner core that can
+explain major aspects of inner core anisotropy.",0204055v1
+2002-12-20,Orbital magnetism in axially deformed sodium clusters: From scissors mode to dia-para magnetic anisotropy,"Low-energy orbital magnetic dipole excitations, known as scissors mode (SM),
+are studied in alkali metal clusters. Subsequent dynamic and static effects are
+explored. The treatment is based on a self-consistent microscopic approach
+using the jellium approximation for the ionic background and the Kohn-Sham mean
+field for the electrons. The microscopic origin of SM and its main features
+(structure of the mode in light and medium clusters, separation into low- and
+high-energy plasmons, coupling high-energy M1 scissors and E2 quadrupole
+plasmons, contributions of shape isomers, etc) are discussed. The scissors M1
+strength acquires large values with increasing cluster size. The mode is
+responsible for the van Vleck paramagnetism of spin-saturated clusters. Quantum
+shell effects induce a fragile interplay between Langevin diamagnetism and van
+Vleck paramagnetism and lead to a remarkable dia-para anisotropy in magnetic
+susceptibility of particular light clusters. Finally, several routes for
+observing the SM experimentally are discussed.",0212084v1
+2003-05-09,The particle-in-cell model for ab initio thermodynamics: implications for the elastic anisotropy of the Earth's inner core,"We assess the quantitative accuracy of the particle-in-cell (PIC)
+approximation used in recent ab initio predictions of the thermodynamic
+properties of hexagonal-close-packed iron at the conditions of the Earth's
+inner core. The assessment is made by comparing PIC predictions for a range of
+thermodynamic properties with the results of more exact calculations that avoid
+the PIC approximation. It is shown that PIC gives very accurate results for
+some properties, but that it gives an incorrect treatment of anharmonic lattice
+vibrations. In addition, our assessment does not support recent PIC-based
+predictions that the hexagonal c/a ratio increases strongly with increasing
+temperature, and we point out that this casts doubt on a proposed
+re-interpretation of the elastic anisotropy of the inner core.",0305033v2
+2003-07-02,Oblique frozen modes in periodic layered media,"We study the classical scattering problem of a plane electromagnetic wave
+incident on the surface of semi-infinite periodic stratified media
+incorporating anisotropic dielectric layers with special oblique orientation of
+the anisotropy axes. We demonstrate that an obliquely incident light, upon
+entering the periodic slab, gets converted into an abnormal grazing mode with
+huge amplitude and zero normal component of the group velocity. This mode
+cannot be represented as a superposition of extended and evanescent
+contributions. Instead, it is related to a general (non-Bloch) Floquet
+eigenmode with the amplitude diverging linearly with the distance from the slab
+boundary. Remarkably, the slab reflectivity in such a situation can be very
+low, which means an almost 100% conversion of the incident light into the
+axially frozen mode with the electromagnetic energy density exceeding that of
+the incident wave by several orders of magnitude. The effect can be realized at
+any desirable frequency, including optical and UV frequency range. The only
+essential physical requirement is the presence of dielectric layers with proper
+oblique orientation of the anisotropy axes. Some practical aspects of this
+phenomenon are considered.",0307021v1
+2004-09-21,The axial ratio of hcp iron at the conditions of the Earth's inner core,"We present ab initio calculations of the high-temperature axial c/a ratio of
+hexagonal-close-packed (hcp) iron at Earth's core pressures, in order to help
+interpret the observed seismic anisotropy of the inner core. The calculations
+are based on density functional theory, which is known to predict the
+properties of high-pressure iron with good accuracy. The temperature dependence
+of c/a is determined by minimising the Helmholtz free energy at fixed volume
+and temperature, with thermal contributions due to lattice vibrations
+calculated using harmonic theory. Anharmonic corrections to the harmonic
+predictions are estimated from calculations of the thermal average stress
+obtained from ab initio molecular dynamics simulations of hcp iron at the
+conditions of the inner core. We find a very gradual increase of axial ratio
+with temperature. This increase is much smaller than found in earlier
+calculations, but is in reasonable agreement with recent high-pressure,
+high-temperature diffraction measurements. This result casts doubt on an
+earlier interpretation of the seismic anisotropy of the inner core.",0409109v1
+2004-10-19,Drift ordered short mean free path closure,"The complete short mean free path description of magnetized plasma in the
+drift ordering has recently been derived. The results correct the previous
+expressions for the ion pressure anisotropy (or parallel ion viscosity) and the
+perpendicular ion viscosity - the ion gyro-viscosity is unchanged. In addition,
+the electron problem is solved for the first time to obtain the electron
+pressure anisotropy (parallel electron viscosity) and the electron
+gyro-viscosity - the perpendicular electron viscosity is negligible. The
+results have been used to obtain a reduced fluid description appropriate to the
+edge of a tokamak. In addition, the complete description has been used to
+evaluate the radial transport of toroidal angular momentum that determines the
+radial electric field and flows in a tokamak.",0410154v1
+2005-03-17,Relationship between acoustic body waves and in situ stresses around a borehole,"This paper shows that there are three types of shape of acoustic body waves
+propagating inside competent and homogeneous formations penetrated by a
+borehole : simple, double, and resonant. This fact is connected to the
+modifications undergone by the area located around a well after drilling in
+relation to in situ state of stress. There are overstressed and understressed
+vertical cylindrical zones with ""bubble-shaped"" cross-sections, in which
+acoustic body waves are supposed to reflect. The horizontal size and the shape
+of the stress modified areas depend on the values of (K1+K2)/2 - with K1=SH/Sv
+(the overburden pressure) and K2=Sh/Sv -, that is to say on the in situ
+horizontal stress and the anisotropy of this stress. The calculation of the
+velocities of the P and S double waves allows us to evaluate the radial
+thicknesses of these stress modified areas. As their values are different
+according to whether they result from P or S waves, we propose an explanation
+based on their wavelengths. The comparisons with other works on the in situ
+stress of the studied boreholes allow us to propose a method for evaluating the
+horizontal stress and its anisotropy, thanks to the estimation of the value
+(K1+K2)/2.",0503153v1
+2006-06-10,Non-dipole angular anisotropy parameters of semi-filled shell atoms,"We present the results of calculations of outer shell non-dipole angular
+anisotropy parameters for semi-filled shell atoms in the Hartree-Fock (HF)
+one-electron approximation and with account of inter-electron correlations in
+the frame of the Spin Polarized Random Phase Approximation with Exchange (SP
+RPAE). We demonstrate for the first time that this characteristic of
+photoionization process is essentially sensitive to the fact whether the
+photoelectron has the same or opposite spin orientation to that of the
+semi-filled shell.",0606093v2
+2007-02-06,Force transmission in a packing of pentagonal particles,"We perform a detailed analysis of the contact force network in a dense
+confined packing of pentagonal particles simulated by means of the contact
+dynamics method. The effect of particle shape is evidenced by comparing the
+data from pentagon packing and from a packing with identical characteristics
+except for the circular shape of the particles. A counterintuitive finding of
+this work is that, under steady shearing, the pentagon packing develops a lower
+structural anisotropy than the disk packing. We show that this weakness is
+compensated by a higher force anisotropy, leading to enhanced shear strength of
+the pentagon packing. We revisit ""strong"" and ""weak"" force networks in the
+pentagon packing, but our simulation data provide also evidence for a large
+class of ""very weak"" forces carried mainly by vertex-to-edge contacts. The
+strong force chains are mostly composed of edge-to-edge contacts with a marked
+zig-zag aspect and a decreasing exponential probability distribution as in a
+disk packing.",0702055v1
+1999-03-12,A Possible Anisotropy in Blackbody Radiation Viewed through Non-uniform Gaseous Matter,"A non-local gauge symmetry of a complex scalar field, which can be trivially
+extended to spinor fields, was demonstrated in a recent paper (Mod.Phys.Lett.
+A13, 1265 (1998) ; hep-th/9902020). The corresponding covariant Lagrangian
+density yielded a new, non-local Quantum Electrodynamics. In this letter we
+show that as a consequence of this new QED, a blackbody radiation viewed
+through gaseous matter appears to show a slight deviation from the Planck
+formula, and propose an experimental test to check this effect. We also show
+that a non-uniformity in this gaseous matter distribution leads to an
+(apparent) spatial anisotropy in the blackbody radiation.",9903043v2
+2003-09-25,Correlation Functions in Spin Chains and Information Theory,"Antiferromagnetic spin chains play an important role in condensed matter
+physics and statistical mechanics. Recently XXX spin chain was discussed in
+relation to the information theory. We consider here localizable entanglement,
+introduced recently by F.Verstraete, M.Popp and J.I.Cirac. That is how much
+entanglement can be localized on two spins on average by performing local
+measurements on the other individual spins in a system of many interacting
+spins. We consider the ground state in antiferromagnetic spin chains and study
+localizable entanglement between two spins as a function of the distance. We
+start with isotropic spin chain.
+  Then we study effect of anisotropy and magnetic field. We conclude that
+anisotropy increases localizable entanglement. We found an explicit dependence
+of critical exponents in XXZ spin chain on magnetic field. We discovered that
+the cases of high symmetry corresponds to high sensitivity of magnetic field.
+We also calculated the concurrence before the measurement to illustrate that
+the measurment raises the concurrence.",0309188v3
+2003-12-03,Entanglement and Quantum Phases in the Anisotropic Ferromagnetic Heisenberg Chain in the Presence of Domain Walls,"We discuss entanglement in the spin-1/2 anisotropic ferromagnetic Heisenberg
+chain in the presence of a boundary magnetic field generating domain walls. By
+increasing the magnetic field, the model undergoes a first-order quantum phase
+transition from a ferromagnetic to a kink-type phase, which is associated to a
+jump in the content of entanglement available in the system. Above the critical
+point, pairwise entanglement is shown to be non-vanishing and independent of
+the boundary magnetic field for large chains. Based on this result, we provide
+an analytical expression for the entanglement between arbitrary spins. Moreover
+the effects of the quantum domains on the gapless region and for
+antiferromagnetic anisotropy are numerically analysed. Finally multiparticle
+entanglement properties are considered, from which we establish a
+characterization of the critical anisotropy separating the gapless regime from
+the kink-type phase.",0312039v3
+2007-04-02,Huge magneto-crystalline anisotropy of x-ray linear dichroism observed on Co/FeMn bilayers,"We present an x-ray spectromicroscopic investigation of single-crystalline
+magnetic FeMn/Co bilayers on Cu(001), using X-ray magnetic circular (XMCD) and
+linear (XMLD) dichroism at the Co and Fe L3 absorption edges in combination
+with photoelectron emission microscopy (PEEM). Using the magnetic coupling
+between the ferromagnetic Co layer and the antiferromagnetic FeMn layer we are
+able to produce magnetic domains with two different crystallographic
+orientations of the magnetic easy axis within the same sample at the same time.
+We find a huge difference in the XMLD contrast between the two types of
+magnetic domains, which we discuss in terms of intrinsic magneto-crystalline
+anisotropy of XMLD of the Co layer. We also demonstrate that due to the high
+sensitivity of the method, the small number of induced ferromagnetic Fe moments
+at the FeMn-Co interface is sufficient to obtain magnetic contrast from XMLD in
+a metallic system.",0704.0182v1
+2007-04-03,Possibility of Gapless Spin Liquid State by One-dimensionalization,"Motivated by the observation of a gapless spin liquid state in
+$\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$, we analyze the anisotropic triangular
+lattice $S=1/2$ Heisenberg model with the resonating valence bond mean-field
+approximation. Paying attention to the small quasi-one-dimensional anisotropy
+of the material, we take an approach from one-dimensional (1D) chains coupled
+with frustrating zig-zag bonds. By calculating one-particle excitation spectra
+changing anisotropy parameter $J'/J$ from the decoupled 1D chains to the
+isotropic triangular lattice, we find almost gapless excitations in the wide
+range from the 1D limit. This one-dimensionalization by frustration is
+considered to be a candidate for the mechanism of the gapless spin liquid
+state.",0704.0313v1
+2007-04-04,Ising-like dynamics and frozen states in systems of ultrafine magnetic particles,"We use Monte-Carlo simulations to study aging phenomena and the occurence of
+spinglass phases in systems of single-domain ferromagnetic nanoparticles under
+the combined influence of dipolar interaction and anisotropy energy, for
+different combinations of positional and orientational disorder. We find that
+the magnetic moments oriente themselves preferably parallel to their anisotropy
+axes and changes of the total magnetization are solely achieved by 180 degree
+flips of the magnetic moments, as in Ising systems. Since the dipolar
+interaction favorizes the formation of antiparallel chain-like structures,
+antiparallel chain-like patterns are frozen in at low temperatures, leading to
+aging phenomena characteristic for spin-glasses. Contrary to the intuition,
+these aging effects are more pronounced in ordered than in disordered
+structures.",0704.0580v1
+2007-04-12,Green function theory versus Quantum Monte Carlo calculations for thin magnetic films,"In this work we compare numerically exact Quantum Monte Carlo (QMC)
+calculations and Green function theory (GFT) calculations of thin ferromagnetic
+films including second order anisotropies. Thereby we concentrate on easy plane
+systems, i.e. systems for which the anisotropy favors a magnetization parallel
+to the film plane. We discuss these systems in perpendicular external field,
+i.e. B parallel to the film normal. GFT results are in good agreement with QMC
+for high enough fields and temperatures. Below a critical field or a critical
+temperature no collinear stable magnetization exists in GFT. On the other hand
+QMC gives finite magnetization even below those critical values. This indicates
+that there occurs a transition from non-collinear to collinear configurations
+with increasing field or temperature. For slightly tilted external fields a
+rotation of magnetization from out-of-plane to in-plane orientation is found
+with decreasing temperature.",0704.1552v1
+2007-04-23,CMB and LSS constraints on a single-field model of inflation,"A new inflationary scenario whose exponential potential $V(\Phi)$ has a
+quadratic dependence on the field $\Phi$ in addition to the standard linear
+term is confronted with the tree-year observations of the Wilkinson-Microwave
+Anisotropy Probe and the Sloan Digital Sky Survey data. The number of e-folds
+($N$), the ratio of tensor-to-scalar perturbations ($r$), the spectral scalar
+index of the primordial power spectrum ($n_s$) and its running ($dn_s/d\ln k$)
+depend on the dimensionless parameter $\alpha$ multiplying the quadratic term
+in the potential. In the limit $\alpha \to 0$ all the results of the standard
+exponential potential are fully recovered. For values of $\alpha \neq 0$, we
+find that the model predictions are in good agreement with the current
+observations of the Cosmic Microwave Background (CMB) anisotropies and
+Large-Scale Structure (LSS) in the Universe.",0704.3043v1
+2007-04-27,Cosmic Rays: The Second Knee and Beyond,"We conduct a review of experimental results on Ultra-High Energy Cosmic Rays
+(UHECR's) including measurements of the features of the spectrum, the
+composition of the primary particle flux and the search for anisotropy in event
+arrival direction. We find that while there is a general consensus on the
+features in the spectrum -- the Second Knee, the Ankle, and (to a lesser
+extent) the GZK Cutoff -- there is little consensus on the composition of the
+primaries that accompany these features. This lack of consensus on the
+composition makes interpretation of the agreed upon features problematic. There
+is also little direct evidence about potential sources of UHECRs, as early
+reports of arrival direction anisotropies have not been confirmed in
+independent measurements.",0704.3721v1
+2007-05-03,Planar spin-transfer device with a dynamic polarizer,"In planar nano-magnetic devices magnetization direction is kept close to a
+given plane by the large easy-plane magnetic anisotropy, for example by the
+shape anisotropy in a thin film. In this case magnetization shows effectively
+in-plane dynamics with only one angle required for its description. Moreover,
+the motion can become overdamped even for small values of Gilbert damping. We
+derive the equations of effective in-plane dynamics in the presence of
+spin-transfer torques. The simplifications achieved in the overdamped regime
+allow to study systems with several dynamic magnetic pieces (``free layers'').
+A transition from a spin-transfer device with a static polarizer to a device
+with two equivalent magnets is observed. When the size difference between the
+magnets is less than critical, the device does not exhibit switching, but goes
+directly into the ``windmill'' precession state.",0705.0406v1
+2007-05-05,Damped Corrections to Inflationary Spectra from a Fluctuating Cutoff,"We reconsider trans-Planckian corrections to inflationary spectra by taking
+into account a physical effect which has been overlooked and which could have
+important consequences. We assume that the short length scale characterizing
+the new physics is endowed with a finite width, the origin of which could be
+found in quantum gravity. As a result, the leading corrections responsible for
+superimposed osillations in the CMB temperature anisotropies are generically
+damped by the blurring of the UV scale. To determine the observational
+ramifications of this damping, we compare it to that which effectively occurs
+when computing the angular power spectrum of temperature anisotropies. The
+former gives an overall change of the oscillation amplitudes whereas the latter
+depends on the angular scale. Therefore, in principle they could be
+distinguished. In any case, the observation of superimposed oscillations would
+place tight constraint on the variance of the UV cutoff.",0705.0747v1
+2007-05-17,Predicting and Understanding Order of Heteroepitaxial Quantum Dots,"Heteroepitaxial self-assembled quantum dots (SAQDs) will allow breakthroughs
+in electronics and optoelectronics. SAQDs are a result of Stranski-Krastanow
+growth whereby a growing planar film becomes unstable after an initial wetting
+layer is formed. Common systems are Ge$_{x}$Si$_{1-x}$/Si and
+In$_{x}$Ga$_{1-x}$As/GaAs. For applications, SAQD arrays need to be ordered.
+The role of crystal anisotropy, random initial conditions and thermal
+fluctuations in influencing SAQD order during early stages of SAQD formation is
+studied through a simple stochastic model of surface diffusion. Surface
+diffusion is analyzed through a linear and perturbatively nonlinear analysis.
+The role of crystal anisotropy in enhancing SAQD order is elucidated. It is
+also found that SAQD order is enhanced when the deposited film is allowed to
+evolve at heights near the critical wetting surface height that marks the onset
+of non-planar film growth.",0705.2601v1
+2007-05-18,Unconventional superconducting pairing by conventional phonons,"The common wisdom that the phonon mechanism of electron pairing in the
+weak-coupling Bardeen-Cooper-Schrieffer (BCS) superconductors leads to
+conventional s-wave Cooper pairs is revised. An inevitable anisotropy of sound
+velocity in crystals makes the phonon-mediated attraction of electrons
+non-local in space providing unconventional Cooper pairs with a nonzero orbital
+momentum in a wide range of electron densities. As a result of this anisotropy
+quasi-two dimensional charge carriers undergo a quantum phase transition from
+an unconventional d-wave superconducting state to a conventional s-wave
+superconductor with more carriers per unit cell. In the opposite
+strong-coupling regime rotational symmetry breaking appears as a result of a
+reduced Coulomb repulsion between unconventional bipolarons dismissing thereby
+some constraints on unconventional pairing in the Bose-Einstein condensation
+(BEC) limit. The conventional phonons, and not superexchange, are shown to be
+responsible for the d-wave symmetry of cuprate superconductors, where the
+on-site Coulomb repulsion is large.",0705.2697v2
+2007-05-22,Spinon-holon interactions in an anisotropic t-J chain: a comprehensive study,"We consider a generalization of the one-dimensional t-J model with
+anisotropic spin-spin interactions. We show that the anisotropy leads to an
+effective attractive interaction between the spinon and holon excitations,
+resulting in a localized bound state. Detailed quantitative analytic
+predictions for the dependence of the binding energy on the anisotropy are
+presented, and verified by precise numerical simulations. The binding energy is
+found to interpolate smoothly between a finite value in the t-Jz limit and zero
+in the isotropic limit, going to zero exponentially in the vicinity of the
+latter. We identify changes in spinon dispersion as the primary factor for this
+non-trivial behavior.",0705.3255v3
+2007-05-23,Dust Distribution during Reionization,"The dust produced by the first generation of stars will be a foreground to
+cosmic microwave background. In order to evaluate the effect of this early
+dust, we calculate the power spectrum of the dust emission anisotropies and
+compare it with the sensitivity limit of the Planck satellite. The spatial
+distribution of the dust is estimated through the distribution of dark matter.
+At small angular scales ($\ell \gtrsim 1000$) the dust signal is found to be
+noticeable with the Planck detector for certain values of dust lifetime and
+production rates. The dust signal is also compared to sensitivities of other
+instruments. The early dust emission anisotropies are finally compared to those
+of local dust and they are found to be similar in magnitude at mm wavelengths.",0705.3403v2
+2007-06-04,CMB Constraint on Radion Evolution in the Brane World Scenario,"In many versions of brane model, the modulus field of extra dimensions, the
+radion, could have cosmological evolution, which induces variation of the Higgs
+vacuum expectation value, $<H>$, resulting in cosmological variation of the
+electron mass $m_e$. The formation of Cosmic Microwave Background (CMB)
+anisotropies is thus affected, causing changes both in the peaks positions and
+amplitudes in the CMB power spectra. Using the three-year Wilkinson Microwave
+Anisotropies Probe (WMAP) CMB data, with the Hubble parameter $H_0$ fixed to be
+the Hubble Space Telescope (HST) result 72 km s$^{-1}$ Mpc$^{-1}$, we obtain a
+constraint on $\rho$, the ratio of the value of $<H>$ at CMB recombination to
+its present value, to be [0.97, 1.02].",0706.0391v2
+2007-06-04,The shear viscosity of the non-commutative plasma,"We compute the shear viscosity of the non-commutative N=4 super Yang-Mills
+quantum field theory at strong coupling using the dual supergravity background.
+Special interest derives from the fact that the background presents an
+intrinsic anisotropy in space through the distinction of commutative and
+non-commutative directions. Despite this anisotropy the analysis exhibits the
+ubiquitous result \eta/s = 1/4\pi for two different shear channels. In order to
+derive this result, we show that the boundary energy momentum tensor must
+couple to the open string metric. As a byproduct we compute the renormalised
+holographic energy momentum tensor and show that it coincides with one in the
+commutative theory.",0706.0411v2
+2007-06-07,Meta-nematic transitions in a bilayer system: Application to the bilayer ruthenate,"It was suggested that the two consecutive metamagnetic transitions and the
+large residual resistivity discovered in Sr$_3$Ru$_2$O$_7$ can be understood
+via the nematic order and its domains in a single layer system. However, a
+recently reported anisotropy between two longitudinal resistivities induced by
+tilting the magnetic field away from the c-axis cannot be explained within the
+single layer nematic picture. To fill the gap in our understanding within the
+nematic order scenario, we investigate the effects of bilayer coupling and
+in-plane magnetic field on the electronic nematic phases in a bilayer system.
+We propose that the in-plane magnetic field in the bilayer system modifies the
+energetics of the domain formation, since it breaks the degeneracy of two
+different nematic orientations. Thus the system reveals a pure nematic phase
+with a resistivity anisotropy in the presence of an in-plane magnetic field. In
+addition to the nematic phase, the bilayer coupling opens a novel route to a
+hidden nematic phase that preserves the x-y symmetry of the Fermi surfaces.",0706.1069v3
+2007-06-19,Logarithmic growth law in the two-dimensional Ising spin glass state resulting from the electron doping in single-layered manganites,"The ac-susceptibility of the electron doped single-layered manganite
+La$_{1.1}$Sr$_{0.9}$MnO$_4$ is analyzed in detail. A quasi two-dimensional
+(2$D$) antiferromagnetic (AFM) order with Ising anisotropy is stabilized below
+$T_N$ $\sim$ 80K. We show that below $T_N$, a rare 2$D$ spin-glass (SG)
+correlation develops with the same Ising anisotropy as the AFM state. Using
+simple scaling arguments of the droplet model, we derive a scaling form for the
+ac-susceptibility data of a 2$D$ SG, which our experimental data follows fairly
+well. Due to simplifications in this 2$D$ case, the proposed scaling form only
+contains two unknown variables $\psi\nu$ and $\tau_0$. Hence, the logarithmic
+growth law of the SG correlation predicted by the droplet model is convincingly
+evidenced by the scaling of our experimental data. The origin and nature of
+this 2$D$ SG state is also discussed.",0706.2691v1
+2007-06-21,Super Heavy Dark Matter and UHECR Anisotropy at Low Energy,"Super Heavy quasi-stable particles are naturally produced in the early
+universe and could represent a substantial fraction of the Dark Matter: the
+so-called Super Heavy Dark Matter (SHDM). The decay of SHDM represents also a
+possible source of Ultra High Energy Cosmic Rays (UHECR), with a reliably
+calculated spectrum of the particles produced in the decay $(\propto
+E^{-1.9})$. The SHDM model for the production of UHECR can explain
+quantitatively only the excess of UHE events observed by AGASA. In the case of
+an observed spectrum not showing the AGASA excess the SHDM model can provide
+only a {\it subdominant} contribution to the UHECR flux. We discuss here the
+basic features of SHDM for the production of a {\it subdominant} UHECR flux, we
+refer our study to the possible signatures of the model at the Auger
+observatory discussing in particular the expected chemical composition and
+anisotropy.",0706.3196v2
+2007-06-25,A coverage independent method to analyze large scale anisotropies,"The arrival time distribution of cosmic ray events is well suited to extract
+information regarding sky anisotropies. For an experiment with nearly constant
+exposure, the frequency resolution one can achieve is given by the inverse of
+the time $T$ during which the data was recorded. For $T$ larger than one
+calendar year the resolution becomes sufficient to resolve the sidereal and
+diurnal frequencies. Using a Fourier expansion on a modified time parameter, we
+show in this note that one can accurately extract sidereal modulations without
+knowledge of the experimental coverage. This procedure also gives the full
+frequency pattern of the event sample under studies which contains important
+information about possible systematics entering in the sidereal analysis. We
+also show how this method allows to correct for those systematics. Finally, we
+show that a two dimensional analysis, in the form of the spherical harmonic
+($Y_l^m$) decomposition, can be performed under the same conditions for all
+$m\ne 0$.",0706.3705v1
+2007-06-26,Cosmic Microwave Background Quadrupole and Ellipsoidal Universe,"Recent Wilkinson Microwave Anisotropy Probe (WMAP) data confirm the Cosmic
+Microwave Background (CMB) quadrupole anomaly. We further elaborate our
+previous proposal that the quadrupole power can be naturally suppressed in
+axis-symmetric universes. In particular, we discuss in greater detail the CMB
+quadrupole anisotropy and considerably improve our analysis. As a result, we
+obtain tighter constraints on the direction of the axis of symmetry as well as
+on the eccentricity at decoupling. We find that the quadrupole amplitude can be
+brought in accordance with observations with an eccentricity at decoupling of
+about 0.35 10^{-2}. Moreover, our determination of the direction of the
+symmetry axis is in reasonable agreement with recent statistical analyses of
+cleaned CMB temperature fluctuation maps obtained by means of improved internal
+linear combination methods as Galactic foreground subtraction technique.",0706.3802v2
+2007-06-27,Transmission des forces dans un milieu composé de grains non sphériques,"We perform a detailed analysis of the contact force network in a dense
+confined packing of pentagonal particles simulated by means of the contact
+dynamics method. The effect of particle shape is evidenced by comparing the
+data from pentagon packing and from a packing with identical characteristics
+except for the circular shape of the particles. A counterintuitive finding of
+this work is that, under steady shearing, the pentagon packing develops a lower
+structural anisotropy than the disk packing. We show that this weakness is
+compensated by a higher force anisotropy, leading to enhanced shear strength of
+the pentagon packing. We revisit ""strong"" and ""weak"" force networks in the
+pentagon packing, but our simulation data provide also evidence for a large
+class of ""very weak"" forces carried mainly by vertex-to-edge contacts. The
+strong force chains are mostly composed of edge-to-edge contacts with a marked
+zig-zag aspect and a decreasing exponential probability distribution as in a
+disk packing.",0706.4007v1
+2007-07-09,"CMB from the South Pole: Past, Present, and Future","South Pole Station offers a unique combination of high, dry, stable
+conditions and well-developed support facilities. Over the past 20 years, a
+sequence of increasingly sophisticated CMB experiments at Pole have built on
+the experience of early pioneering efforts, producing a number of landmark
+contributions to the field. Telescopes at the South Pole were among the first
+to make repeated detections of degree-scale CMB temperature anisotropy and to
+map out the harmonic structure of its acoustic peaks. More recent achievements
+include the first detection of polarization of the CMB and the most precise
+measurements of the temperature power spectrum at small angular scales. New CMB
+telescopes at the South Pole are now making ultra-deep observations of the
+large-scale polarization of the CMB and of its secondary temperature
+anisotropies on arcminute scales. These two observing goals represent the
+current frontiers of CMB research, focused on constraining Inflation and the
+nature of Dark Energy. The South Pole now hosts an array of CMB observing
+platforms covering a wide range of angular scales and supporting very long
+integration times on the cleanest sky available, and thus should play an
+increasing role in pushing these frontiers of CMB research.",0707.1075v1
+2007-07-10,Polarization anisotropy in the optical properties of silicon ellipsoids,"A new real space quantum mechanical approach with local field effects
+included is applied to the calculation of the optical properties of silicon
+nanocrystals. Silicon ellipsoids are studied and the role of surface
+polarization is discussed in details. In particular, surface polarization is
+shown to be responsible for a strong optical anisotropy in silicon ellipsoids,
+much more pronounced with respect to the case in which only quantum confinement
+effects are considered. The static dielectric constant and the absorption
+spectra are calculated, showing that the perpendicular and parallel components
+have a very different dependence on the ellipsoid aspect ratio. Then, a
+comparison with the classical dielectric model is performed, showing that the
+model only works for large and regular structures, but it fails for thin
+elongated ellipsoids.",0707.1499v1
+2007-07-13,Nflation: observable predictions from the random matrix mass spectrum,"We carry out numerical investigations of the perturbations in Nflation models
+where the mass spectrum is generated by random matrix theory. The
+tensor-to-scalar ratio and non-gaussianity are already known to take the
+single-field values, and so the density perturbation spectral index is the main
+parameter of interest. We study several types of random field initial
+conditions, and compute the spectral index as a function of mass spectrum
+parameters. Comparison with microwave anisotropy data from the Wilkinson
+Microwave Anisotropy Probe shows that the model is currently viable in the
+majority of its parameter space.",0707.1982v2
+2007-07-19,CMB temperature anisotropies from third order gravitational perturbations,"In this paper we present a complete computation of the Cosmic Microwave
+Background (CMB) anisotropies up to third order from gravitational
+perturbations accounting for scalar, vector and tensor perturbations. We then
+specify our results to the large scale limit, providing the evolution of the
+gravitational potentials in a flat universe filled with matter and cosmological
+constant which characterizes the Integrated Sachs-Wolfe effect. As a byproduct
+in the large scale approximation we are able to give non-perturbative solutions
+for the photon geodesic equations. Our results are the first step to provide a
+complete theoretical prediction for cubic non-linearities which are
+particularly relevant for characterizing the level of non-Gaussianity in the
+CMB through the detection of the four-point angular connected correlation
+function (trispectrum). For this purpose we also allow for generic initial
+conditions due to primordial non-Gaussianity.",0707.2894v2
+2007-07-23,Dark matter annihilation near a black hole: plateau vs. weak cusp,"Dark matter annihilation in so-called ``spikes'' near black holes is believed
+to be an important method of indirect dark matter detection. In the case of
+circular particle orbits, the density profile of dark matter has a plateau at
+small radii, the maximal density being limited by the annihilation
+cross-section. However, in the general case of arbitrary velocity anisotropy
+the situation is different. Particulary, for isotropic velocity distribution
+the density profile cannot be shallower than r^{-1/2} in the very centre.
+Indeed, a detailed study reveals that in many cases the term ``annihilation
+plateau'' is misleading, as the density actually continues to rise towards
+small radii and forms a weak cusp, rho ~ r^{-(beta+1/2)}, where beta is the
+anisotropy coefficient. The annihilation flux, however, does not change much in
+the latter case, if averaged over an area larger than the annihilation radius.",0707.3334v2
+2007-07-27,Theory for Magnetic Anisotropy of Field-Induced Insulator-to-Metal Transition in Cubic Kondo Insulator YbB_{12},"Magnetization and energy gap of Kondo insulator YbB_{12} are calculated
+theoretically based on the previously proposed tight-binding model composed of
+Yb 5d$\epsilon$ and 4f $\Gamma_8$ orbitals. It is found that magnetization
+curves are almost isotropic, naturally expected from the cubic symmetry, but
+that the gap-closing field has an anisotropy: the gap closes faster for the
+field in (100) direction than in (110) and (111) directions, in accord with the
+experiments. This is qualitatively understood by considering the maximal
+eigenvalues of the total angular momentum operators projected on each direction
+of the magnetic field. But the numerical calculation based on the band model
+yields better agreement with the experiment.",0707.4048v1
+2007-07-28,"Magnetization and Magnetoscrition of van Vleck antiferromagnets with magnetic anisotropy of ""easy-plane"" type","The theoretical description of quantum phase transition, induced by the
+external magnetic field, into antiferromagnetic state in the van Vleck -
+singlet - magnet with a single-ion anisotropy of ""easy-plane"" type and ion spin
+S=1 is proposed. It is shown that the spin polarization of the ground
+non-degenerated state proves to be the order parameter of such a transition and
+that the Landau thermodynamic approach can be employed for its (transition)
+description. The magnetic properties which include the field behavior of the
+magnetization and magnetic susceptibility of the antiferromagnetic phase in the
+fields of different directions are studied. The peculiarities of induced
+magnetostriction in van Vleck antiferromagnet, which as well as magnetization
+has a singularity in the phase transition point, are investigated. An attempt
+is made for qualitative comparison of results obtained with avaliable
+experimental data.",0707.4227v1
+2007-07-30,Tuning of ferromagnetism through anion substitution in Ga-Mn-pnictide ferromagnetic semiconductors,"We have synthesized Ga1-xMnxAs1-yPy and Ga1-xMnxP1-yNy by the combination of
+ion implantation and pulsed-laser melting. We find that the incorporation of
+isovalent impurities with smaller atomic radii leads to a realignment of the
+magnetic easy axis in Ga1-xMnxP1-yNy/GaP and Ga1-xMnxAs1-yPy/GaAs thin films
+from in-plane to out-of-plane. This tensile-strain-induced magnetic anisotropy
+is reminiscent of that observed in Ga1-xMnxAs grown on larger lattice constant
+(In,Ga)As buffer layers indicating that the role of strain in determining
+magnetic anisotropy is fundamental to III-Mn-V materials. In addition, we
+observe a decrease in the ferromagnetic Curie temperature in Ga1-xMnxAs1-yPy
+with increasing y from 0 to 0.028. Such a decrease may result from localization
+of holes as the P/As ratio on the Group V sublattice increases.",0707.4490v1
+2007-08-07,Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy,"We present the first results of directional point-contact spectroscopy in
+high quality CaC6 samples both along the ab plane and in the c-axis direction.
+The superconducting order parameter \Delta(0), obtained by fitting the
+Andreev-reflection (AR) conductance curves at temperatures down to 400 mK with
+the single-band 3D Blonder-Tinkham-Klapwijk model, presents two different
+distributions in the two directions of the main current injection, peaked at
+1.35 and 1.71 meV, respectively. By ab-initio calculations of the AR
+conductance spectra, we show that the experimental results are in good
+agreement with the recent predictions of gap anisotropy in CaC6.",0708.0921v2
+2007-08-13,Theoretical analysis of magnetic force microscopy contrast in multidomain states of magnetic superlattices with perpendicular anisotropy,"Recently synthesized magnetic multilayers with strong perpendicular
+anisotropy exhibit unique magnetic properties including the formation of
+specific multidomain states. In particular, antiferromagnetically coupled
+multilayers own rich phase diagrams that include various multidomain ground
+states. Analytical equations have been derived for the stray-field components
+of these multidomain states in perpendicular multilayer systems. In particular,
+closed expressions for stray fields in the case of ferromagnetic and
+antiferromagnetic stripes are presented. The theoretical approach provides a
+basis for the analysis of magnetic force microscopy (MFM) images from this
+novel class of nanomagnetic systems. Peculiarities of the MFM contrast have
+been calculated for realistic tip models. These characteristic features in the
+MFM signals can be employed for the investigations of the different multidomain
+modes. The obtained results are applied for the analysis of multidomain modes
+that have been reported earlier in the literature from experiments on [Co/Cr]Ru
+superlattices.",0708.1570v4
+2007-08-16,Effective Spin-1/2 Description of Transverse-Field-Induced Random Fields in Dipolar Spin Glasses with Strong Single-Ion Anisotropy,"We present analytical and numerical evidence for the validity of an effective
+S=1/2 approach to the description of random field generation in S>=1, and
+especially in an S=1, dipolar spin glass models with strong uniaxial Ising
+anisotropy and subject to weak external magnetic field Bx transverse to the
+Ising direction. Explicitely Bx-dependent random fields are shown to naturally
+emerge in the effective low-energy description of a microscopic S=1 toy model.
+We discuss our results in relation to recent theoretical studies pertaining to
+the topic of Bx-induced random fields in the LiHo$_x$Y$_{1-x}$F$_4$ magnetic
+materials with the Ho$^{3+}$ Ising moments subject to a transverse field. We
+show that the S_{eff}=1/2 approach is able to capture both the qualitative and
+quantitative aspects of the physics at small Bx, giving results that agree with
+those obtained using conventional second order perturbation theory.",0708.2286v1
+2007-09-04,Rigorous Solution of the Spin-1 Quantum Ising Model with Single-ion Anisotropy,"We solve the spin-1 quantum Ising model with single-ion anisotropy by mapping
+it onto a series of segmented spin-1/2 transverse Ising chains, separated by
+the $S^z =0$ states called holes. A recursion formula is derived for the
+partition function to simplify the summation of hole configurations. This
+allows the thermodynamic quantities of this model to be rigorously determined
+in the thermodynamic limit. The low temperature behavior is governed by the
+interplay between the hole excitations and the fermionic excitations within
+each spin-1/2 Ising segment. The quantum critical fluctuations around the Ising
+critical point of the transverse Ising model are strongly suppressed by the
+hole excitations.",0709.0337v3
+2007-09-05,Strong Imbalanced Turbulence,"We consider stationary, forced, imbalanced, or cross-helical MHD Alfvenic
+turbulence where the waves traveling in one direction have higher amplitudes
+than the opposite waves. This paper is dedicated to so-called strong
+turbulence, which cannot be treated perturbatively. Our main result is that the
+anisotropy of the weak waves is stronger than the anisotropy of a strong waves.
+We propose that critical balance, which was originally conceived as a causality
+argument, has to be amended by what we call a propagation argument. This
+revised formulation of critical balance is able to handle the imbalanced case
+and reduces to old formulation in the balanced case. We also provide
+phenomenological model of energy cascading and discuss possibility of
+self-similar solutions in a realistic setup of driven turbulence.",0709.0554v2
+2007-09-14,Influence of particle shape on shear stress in granular media,"We analyze the contact and force networks in a dense confined packing of
+pentagonal particles simulated by means of the contact dynamics method. The
+particle shape effect is evidenced by comparing the data from pentagon packing
+and from a packing with identical characteristics except for the circular shape
+of the particles. A surprising observation is that the pentagon packing
+develops a lower structural anisotropy than the disk packing. We show in this
+work that this weakness is compensated by a higher force anisotropy that leads
+to enhanced shear strength of the pentagon packing. With the polygonal shape of
+the particles, the strong force chains are mostly composed of edge-to-edge
+contacts with a marked zig-zag aspect.",0709.2241v1
+2007-09-18,Clustering properties of ultrahigh energy cosmic rays and the search for their astrophysical sources,"The arrival directions of ultrahigh energy cosmic rays (UHECRs) may show
+anisotropies on all scales, from just above the experimental angular resolution
+up to medium scales and dipole anisotropies. We find that a global comparison
+of the two-point auto-correlation function of the data with the one of
+catalogues of potential sources is a powerful diagnostic tool. In particular,
+this method is far less sensitive to unknown deflections in magnetic fields
+than cross-correlation studies while keeping a strong discrimination power
+among source candidates. We illustrate these advantages by considering ordinary
+galaxies, gamma ray bursts and active galactic nuclei as possible sources.
+Already the sparse publicly available data suggest that the sources of UHECRs
+may be a strongly clustered sub-sample of galaxies or of active galactic
+nuclei. We present forecasts for various cases of source distributions which
+can be checked soon by the Pierre Auger Observatory.",0709.2712v2
+2007-09-24,Nonlinear growth of firehose and mirror fluctuations in turbulent galaxy-cluster plasmas,"In turbulent high-beta astrophysical plasmas (exemplified by the galaxy
+cluster plasmas), pressure-anisotropy-driven firehose and mirror fluctuations
+grow nonlinearly to large amplitudes, dB/B ~ 1, on a timescale comparable to
+the turnover time of the turbulent motions. The principle of their nonlinear
+evolution is to generate secularly growing small-scale magnetic fluctuations
+that on average cancel the temporal change in the large-scale magnetic field
+responsible for the pressure anisotropies. The presence of small-scale magnetic
+fluctuations may dramatically affect the transport properties and, thereby, the
+large-scale dynamics of the high-beta astrophysical plasmas.",0709.3828v2
+2007-09-30,Difficulty in the Fermi-Liquid-Based Theory for the In-Plane Magnetic Anisotropy in Untwinned High-T_c Superconductor,"Recently, Eremin and Manske [1] presented a oneband Fermi-liquid theory for
+the in-plane magnetic anisotropy in untwinned high-Tc superconductor
+YBa2Cu3O6:85 (YBCO). They claimed that they found good agreement with inelastic
+neutron scattering (INS) spectra. In this Comment, we point out that their
+conclusion on this important problem may be questionable due to an error in
+logic about the orthorhombicity delta_0 characterizing the lattice structure of
+YBCO. In Ref. [1], a single band at delta_0>0 is proved to be in accordance
+with the angle resolved photoemission spectroscopy (ARPES) on untwinned YBCO.
+But in their Erratum in PRL[3], they admit that delta_0= -0.03 was used to fit
+the INS data. Hence publications [1,3] contain errors that we believe
+invalidate their approach.",0710.0127v1
+2007-10-10,CMB Anisotropies and Inflation from Non-Standard Spinors,"The apparent alignment of the cosmic microwave background multipoles on large
+scales challenges the standard cosmological model. Scalar field inflation is
+isotropic and cannot account for the observed alignment. We explore the
+imprints, a non-standard spinor driven inflation would leave on the cosmic
+microwave background anisotropies. We show it is natural to expect an
+anisotropic inflationary expansion of the Universe which has the effect of
+suppressing the low multipole amplitude of the primordial power spectrum, while
+at the same time to provide the usual inflationary features.",0710.2003v4
+2007-10-12,Slonczewski windmill with dissipation and asymmetry,"J. Slonczewski invented spin-transfer effect in layered systems in 1996.
+Among his first predictions was the regime of ``windmill motion'' of a
+perfectly symmetric spin valve where the magnetizations of the layers rotate in
+a fixed plane keeping the angle between them constant. Since ``windmill'' was
+predicted to happen in the case of zero magnetic anisotropy, while in most
+experimental setups the anisotropy is significant, the phenomenon was not a
+subject of much research. However, the behavior of the magnetically isotropic
+device is related to the interesting question of current induced ferromagnetism
+and is worth more attention. Here we study the windmill regime in the presence
+of dissipation, exchange interaction, and layer asymmetry. It is shown that the
+windmill rotation is almost always destroyed by those effects, except for a
+single special value of electric current, determined by the parameters of the
+device.",0710.2564v1
+2007-10-17,Lensing Systematics from Space: Modeling PSF effects in the SNAP survey,"Anisotropy in the point spread function (PSF) contributes a systematic error
+to weak lensing measurements. In this study we use a ray tracer that
+incorporates all the optical elements of the SNAP telescope to estimate this
+effect. Misalignments in the optics generates PSF anisotropy, which we
+characterize by its ellipticity. The effect of three time varying effects:
+thermal drift, guider jitter, and structural vibration on the PSF are estimated
+for expected parameters of the SNAP telescope. Multiple realizations of a
+thousand square degree mock survey are then generated to include the systematic
+error pattern induced by these effects. We quantify their contribution to the
+power spectrum of the lensing shear. We find that the dominant effect comes
+from the thermal drift, which peaks at angular wavenumbers l ~ 10^3, but its
+amplitude is over one order of magnitude smaller than the size of the expected
+statistical error. While there are significant uncertainties in our modeling,
+our study indicates that time-varying PSFs will contribute at a smaller level
+than statistical errors in SNAP's weak lensing measurements.",0710.3355v1
+2007-10-31,Direction-Dependent CMB Power Spectrum and Statistical Anisotropy from Noncommutative Geometry,"Modern cosmology has now emerged as a testing ground for theories beyond the
+standard model of particle physics. In this paper, we consider quantum
+fluctuations of the inflaton scalar field on certain noncommutative spacetimes
+and look for noncommutative corrections in the cosmic microwave background
+(CMB) radiation. Inhomogeneities in the distribution of large scale structure
+and anisotropies in the CMB radiation can carry traces of noncommutativity of
+the early universe. We show that its power spectrum becomes direction-dependent
+when spacetime is noncommutative. (The effects due to noncommutativity can be
+observed experimentally in the distribution of large scale structure of matter
+as well.) Furthermore, we have shown that the probability distribution
+determining the temperature fluctuations is not Gaussian for our noncommutative
+spacetimes.",0710.5897v3
+2007-11-10,Strong luminescence quantum efficiency enhancement near prolate metal nanoparticles: dipolar versus higher-order modes,"We present a theoretical study of the radiative and nonradiative decay rates
+of an optical emitter in close proximity to a prolate-shaped metal
+nanoparticle. We use the model developed by Gersten and Nitzan, that we correct
+for radiative reaction and dynamic depolarization and extend for prolate
+particle shapes. We show that prolate-shaped metal nanoparticles can lead to
+much higher quantum efficiency enhancements than corresponding spherical
+nanoparticles. For properly engineered emitter-nanoparticle geometries, quantum
+efficiency enhancements from an initial value of 1% (in absence of the
+nanoparticle) to 70% are feasible. We describe the anisotropy-induced
+enhancement effects in terms of large field enhancements near the metal tips
+that cause strong coupling to the (radiative) dipolar modes. For increasing
+particle anisotropy, a strong spectral separation between radiative dipolar and
+dark higher-order modes occurs, which leads to higher radiative efficiencies
+for anisotropic particles. In addition, we demonstrate that for large (> 100
+nm) nanoparticles, the influence of Ohmic losses on plasmon-enhanced
+luminescence is substantially reduced, which implies that, if prolate shaped,
+even lossy metals such as Al and Cu are suitable materials for optical
+nano-antennas.",0711.1591v1
+2007-11-13,Shape of Heteroepitaxial Island Determined by Asymmetric Detachment,"Square lattice gas models for heteroepitaxial growth are studied by means of
+kinetic Monte Carlo simulations, in order to find a possible origin of
+anisotropic island shape observed in growth experiments of long organic
+molecules. When deposited molecules form clusters irreversibly at their
+encounter during surface diffusion, islands grow in a ramified dendritic shape,
+similar to DLA. Introduction of molecular detachment from edges makes islands
+compact with smooth edges. Tilting of adsorbed long molecules or steps in a
+vicinal substrate may induce orientation-dependence in the detachment rate of
+edge molecules from an island. In simulations with orientation-dependent
+detachment rates, a clear anisotropy in an island shape is observed. Shape
+anisotropy on a vicinal substrate is enhanced as steps get dense, in agreement
+to the experimental observation.",0711.1903v1
+2007-11-20,A rotating hollow cone anisotropy of TeV emission from binary systems,"We show that TeV gamma-ray emission produced via interactions of high-energy
+particles with anisotropic radiation field of a massive star in binary systems
+should have a characteristic rotating hollow cone anisotropy pattern. The
+hollow cone, whose axis is directed away from the massive star, rotates with
+the period equal to the orbital period of the system. We note that the two
+maxima pattern of the TeV energy band lightcurve of the gamma-ray loud binary
+LS 5039 can be interpreted in terms of this rotating hollow cone model.
+Adopting such an interpretation, we are able to constrain the geometry of the
+system - either the inclination angle of the binary orbit, or the elevation of
+the gamma-ray emission region above the orbital plane.",0711.3085v3
+2007-11-30,The impact of going beyond the Maxwell distribution in direct dark matter detection rates,"We consider direct dark matter detection rates and investigate the difference
+between a standard Maxwell-Boltzmann velocity distribution and a ""realistic""
+distribution like the ones extracted from numerical N-body simulations. Sizable
+differences are observed when such results are compared to the standard
+Maxwell-Boltzmann distribution. For a light target both the total rate and the
+annual modulation are reduced by ~25%. For a heavy target the total rate is
+virtually unchanged, whereas the annual modulation is modified by up to 50%,
+depending on the WIMP mass and detector energy threshold. We also consider the
+effect of a possible velocity anisotropy, and the effect is found to be largest
+for a light target For the realistic velocity distribution the anisotropy may
+reduce the annual modulation, in contrast to the Maxwell-Boltzmann case.",0711.4895v1
+2007-12-03,"Creep, recovery, and waves in a nonlinear fiber-reinforced viscoelastic solid","We present a constitutive model capturing some of the experimentally observed
+features of soft biological tissues: nonlinear viscoelasticity, nonlinear
+elastic anisotropy, and nonlinear viscous anisotropy. For this model we derive
+the equation governing rectilinear shear motion in the plane of the fiber
+reinforcement; it is a nonlinear partial differential equation for the shear
+strain. Specializing the equation to the quasi-static processes of creep and
+recovery, we find that usual (exponential-like) time growth and decay exist in
+general, but that for certain ranges of values for the material parameters and
+for the angle between the shearing direction and the fiber direction, some
+anomalous behaviors emerge. These include persistence of a nonzero strain in
+the recovery experiment, strain growth in recovery, strain decay in creep,
+disappearance of the solution after a finite time, and similar odd
+comportments. For the full dynamical equation of motion, we find kink
+(traveling wave) solutions which cannot reach their assigned asymptotic limit.",0712.0229v1
+2007-12-14,The effect of unbound stars on the mass modelling of the Fornax dwarf,"We discuss how different approaches to selecting member stars in kinematic
+samples of dwarf spheroidal galaxies affect the estimates of their mass and
+anisotropy of stellar orbits. We demonstrate that the selection of members is
+an additional source of error compared to the usual uncertainties due to the
+sampling of velocity moments. As an example we use the kinematic data set for
+202 stars in the Fornax dwarf galaxy for which we model the velocity dispersion
+profile and estimate the mass-to-light ratio and anisotropy assuming that mass
+follows light. We also show that stronger constraints on these parameters can
+be obtained if kurtosis of the velocity distribution is included in the
+analysis. Using the Besancon model of the Milky Way we demonstrate that the
+majority of contamination in Fornax probably comes from the Milky Way stars.",0712.2372v1
+2007-12-23,Phase diagram of the one dimensional anisotropic Kondo-necklace model,"The one dimensional anisotropic Kondo-necklace model has been studied by
+several methods. It is shown that a mean field approach fails to gain the
+correct phase diagram for the Ising type anisotropy. We then applied the spin
+wave theory which is justified for the anisotropic case. We have derived the
+phase diagram between the antiferromagnetic long range order and the Kondo
+singlet phases. We have found that the exchange interaction (J) between the
+itinerant spins and local ones enhances the quantum fluctuations around the
+classical long range antiferromagnetic order and finally destroy the ordered
+phase at the critical value, J_c. Moreover, our results show that the onset of
+anisotropy in the XY term of the itinerant interactions develops the
+antiferromagnetic order for J<J_c. This is in agreement with the qualitative
+feature which we expect from the symmetry of the anisotropic XY interaction. We
+have justified our results by the numerical Lanczos method where the structure
+factor at the antiferromagnetic wave vector diverges as the size of system goes
+to infinity.",0712.3914v2
+2007-12-24,Topological Defects in Spherical Nematics,"We study the organization of topological defects in a system of nematogens
+confined to the two-dimensional sphere (S^2). We first perform Monte Carlo
+simulations of a fluid system of hard rods (spherocylinders) living in the
+tangent plane of S^2. The sphere is adiabatically compressed until we reach a
+jammed nematic state with maximum packing density. The nematic state exhibits
+four +1/2 disclinations arrayed on a great circle rather than at the vertices
+of a regular tetrahedron. This arises from the high elastic anisotropy of the
+system in which splay (K_1) is far softer than bending (K_3). We also introduce
+and study a lattice nematic model on S^2 with tunable elastic constants and map
+out the preferred defect locations as a function of elastic anisotropy. We
+establish the existence of a one-parameter family of degenerate ground states
+in the extreme splay-dominated limit K_1/K_3 -> 0. Thus the global defect
+geometry is controllable by tuning the relative splay to bend modulus.",0712.4012v3
+2008-01-02,Cosmic microwave background constraints on a decaying cosmological term related to the thermal evolution,"We constrain the thermal evolution of the universe with a decaying
+cosmological term by using the method of the analysis for the Wilkinson
+Microwave Anisotropy Probe (WMAP) observation data. The cosmological term is
+assumed to be a function of the scale factor that increases toward the early
+universe, and the radiation energy density is lower compared to that in the
+model with the standard cosmological ""constant"" (LCDM). The decrease in the
+radiation density affects the thermal history of the universe; e.g. the photon
+decoupling occurs at higher-z compared to the case of the standard LCDM model.
+As a consequence, a decaying cosmological term affects the cosmic microwave
+background anisotropy. Thanks to the Markov-chain Monte Carlo method, we
+compare the angular power spectrum in the decaying LCDM model with the CMB
+data, and we get severe constraints on parameters of the model.",0801.0290v2
+2008-01-03,High resolution 3D laser scanner measurements of a strike-slip fault quantify its morphological anisotropy at all scales,"The surface roughness of a recently exhumed strikeslip fault plane has been
+measured by three independent 3D portable laser scanners. Digital elevation
+models of several fault surface areas, from 1 m2 to 600 m2, have been measured
+at a resolution ranging from 5 mm to 80 mm. Out of plane height fluctuations
+are described by non-Gaussian distribution with exponential long range tails.
+Statistical scaling analyses show that the striated fault surface exhibits
+self-affine scaling invariance with a small but significant directional
+morphological anisotropy that can be described by two scaling roughness
+exponents, H1 = 0.7 in the direction of slip and H2 = 0.8 perpendicular to the
+direction of slip.",0801.0544v1
+2008-01-06,Evolution of Massive Blackhole Triples II -- The effect of the BH triples dynamics on the structure of the galactic nuclear,"In this paper, we investigate the structures of galaxies which either have or
+have had three BHs using $N$-body simulations, and compare them with those of
+galaxies with binary BHs. We found that the cusp region of a galaxy which have
+(or had) triple BHs is significantly larger and less dense than that of a
+galaxy with binary BHs of the same mass. Moreover, the size of the cusp region
+depends strongly on the evolution history of triple BHs, while in the case of
+binary BHs, the size of the cusp is determined by the mass of the BHs. In
+galaxies which have (or had) three BHs, there is a region with significant
+radial velocity anisotropy, while such a region is not observed in galaxies
+with binary BH. These differences come from the fact that with triple BHs the
+energy deposit to the central region of the galaxy can be much larger due to
+multiple binary-single BH scatterings. Our result suggests that we can
+discriminate between galaxies which experienced triple BH interactions with
+those which did not, through the observable signatures such as the cusp size
+and velocity anisotropy.",0801.0859v1
+2008-01-14,"Azimuthal Anisotropy: Ridges, Recombination and Breaking of Quark Number Scaling","Azimuthal anisotropy is studied by taking into account the ridges created by
+semi-hard scattering, which is sensitive to the initial spatial configuration
+in non-central heavy-ion collisions. No rapid thermalization is required.
+Although hydrodynamics is not used in this study, the validity of
+hydrodynamical expansion is not excluded at later time after equilibration is
+achieved. Phenomenological properties of the bulk and ridge behaviors are used
+as inputs to determine the elliptic flow of pion and proton at low p_T. At
+intermediate p_T the recombination of shower partons with thermal partons
+becomes more important. The phi dependence arises from the variation of the
+in-medium path length of the hard parton that generates the shower. The p_T
+dependence of v_2 is therefore very different at intermediate p_T compared to
+that at low p_T. Quark number scaling of v_2 is shown to be only approximately
+valid at low p_T, but is broken at intermediate p_T, even though recombination
+is the mechanism of hadronization in all p_T regions considered.",0801.2183v2
+2008-01-24,"Spin-driven ferroelectricity and possible antiferroelectricity in triangular lattice antiferromagnets ACrO2 (A = Cu, Ag, Li, or Na)","Correlation between dielectric and magnetic properties was investigated on
+the triangular lattice antiferromagnets ACrO2 (A= Cu, Ag, Li, or Na) showing
+120-degree spiral spin structure with easy-axis anisotropy. For the A= Cu and
+Ag compounds with delafossite structure, ferroelectric polarization emerges
+upon the spiral spin order, implying the strong coupling between the
+ferroelectricity and spiral spin structure. On the other hand, for the A = Li
+and Na compounds with ordered rock salt structure, no polarization but only
+clear anomalies in dielectric constant can be observed upon the spiral spin
+order. The absence of polarization can be interpreted as the antiferroelectric
+state induced by the alternate stacking of Cr3+ layer with opposite spin vector
+chirality. These results imply that a vast range of trigonally stacked
+triangular-lattice systems with 120-degree spin structure can be multiferroic,
+irrespective of their magnetic anisotropy.",0801.3757v1
+2008-01-28,GaMnAs-based hybrid multiferroic memory device,"A rapidly developing field of spintronics is based on the premise that
+substituting charge with spin as a carrier of information can lead to new
+devices with lower power consumption, non-volatility and high operational
+speed. Despite efficient magnetization detection, magnetization manipulation is
+primarily performed by current-generated local magnetic fields and is very
+inefficient. Here we report a novel non-volatile hybrid multiferroic memory
+cell with electrostatic control of magnetization based on strain-coupled GaMnAs
+ferromagnetic semiconductor and a piezoelectric material. We use the
+crystalline anisotropy of GaMnAs to store information in the orientation of the
+magnetization along one of the two easy axes, which is monitored via transverse
+anisotropic magnetoresistance. The magnetization orientation is switched by
+applying voltage to the piezoelectric material and tuning magnetic anisotropy
+of GaMnAs via the resulting stress field.",0801.4191v1
+2008-01-28,Dynamical correlations in the spin-half two-channel Kondo model,"Dynamical correlations of various local operators are studied in the
+spin-half two-channel Kondo (2CK) model in the presence of channel anisotropy
+or external magnetic field. A conformal field theory-based scaling approach is
+used to predict the analytic properties of various spectral functions in the
+vicinity of the two-channel Kondo fixed point. These analytical results compare
+well with highly accurate density matrix numerical renormalization group
+results. The universal cross-over functions interpolating between
+channel-anisotropy or magnetic field-induced Fermi liquid regimes and the
+two-channel Kondo, non-Fermi liquid regimes are determined numerically. The
+boundaries of the real 2CK scaling regime are found to be rather restricted,
+and to depend both on the type of the perturbation and on the specific operator
+whose correlation function is studied. In a small magnetic field, a universal
+resonance is observed in the local fermion's spectral function. The dominant
+superconducting instability appears in the composite superconducting channel.",0801.4272v1
+2008-01-29,The Integrated Sachs-Wolfe Effect in Interacting Dark Energy Models,"Models with dark energy decaying into dark matter have been proposed in
+Cosmology to solve the coincidence problem. We study the effect of such
+coupling on the cosmic microwave background temperature anisotropies. The
+interaction changes the rate of evolution of the metric potentials, the growth
+rate of matter density perturbations and modifies the Integrated Sachs-Wolfe
+component of cosmic microwave background temperature anisotropies, enhancing
+the effect. Cross-correlation of galaxy catalogs with CMB maps provides a model
+independent test to constrain the interaction. We particularize our analysis
+for a specific interacting model and show that galaxy catalogs with median
+redshifts $z_m=0.1-0.9$ can rule out models with an interaction parameter
+strength of $c^2\simeq 0.1$ better than 99.95% confidence level. Values of
+$c^2\le 0.01$ are compatible with the data and may account for the possible
+discrepancy between the fraction of dark energy derived from WMAP 3yr data and
+the fraction obtained from the ISW effect. Measuring the fraction of dark
+energy by these two methods could provide evidence of an interaction.",0801.4517v2
+2008-02-04,Effects of phonon interaction on the pairing in the high-T$c$ superconductors,"We study the effects of phonon interaction on the superconducting pairing in
+the background of a d-wave gap, mediated by antiferromagnetic (AFM) spin
+fluctuations, using coupled BCS gap equations. We found that phonon interaction
+can induce a s-wave component to the d-wave gap in the (D+S) form with an
+interaction anisotropy and in the (D+$i$S) form without anisotropy,
+respectively. In either case, however, T$_c$ is not enhanced compared to the
+pure d-wave pairing without phonon interaction. On the other hand, anisotropic
+phonon interaction can dramatically enhance the d-wave pairing itself and
+therefore T$_c$, together with the AFM spin fluctuation interaction. This
+(D$_{AFM}$ + D$_{ph}$) type pairing exhibits strongly reduced isotope
+coefficient despite the large enhancement of T$_c$ by phonon interaction.
+Finally, we study the combined type of (D$_{AFM}$ + D$_{ph}$ +$i$S)) gap and
+calculate the penetration depth and specific heat to be compared with the
+experiments.",0802.0328v1
+2008-02-05,Green's function theory for spin-1/2 ferromagnets with an easy-plane exchange anisotropy,"The many-body Green's function theory with the random-phase approximation is
+applied to the study of easy-plane spin-1/2 ferromagnets in an in-plane
+magnetic field. We demonstrate that the usual procedure, in which only the
+three Green's functions $<< S_i^\mu;S_j^->>$ ($\mu=+,-,z$) are used, yields
+unreasonable results in this case. Then the problem is discussed in more detail
+by considering all combinations of Green's functions. We can derive one more
+equation, which cannot be obtained by using only the set of the above three
+Green's functions, and point out that the two equations contradict each other
+if one demands that the identities of the spin operators are exactly satisfied.
+We discuss the cause of the contradiction and attempt to improve the method in
+a self consistent way. In our procedure, the effect of the anisotropy can be
+appropriately taken into account, and the results are in good agreement with
+the quantum Monte Carlo calculations.",0802.0559v2
+2008-02-05,Cumulative effect of Weibel-type instabilities in counterstreaming plasmas with non-Maxwellian anisotropies,"Counterstreaming plasma structures are widely present in laboratory
+experiments and astrophysical systems, and they are investigated either to
+prevent unstable modes arising in beam-plasma experiments or to prove the
+existence of large scale magnetic fields in astrophysical objects.
+Filamentation instability arises in a counterstreaming plasma and is
+responsible for the magnetization of the plasma. Filamentationally unstable
+mode is described by assuming that each of the counterstreaming plasmas has an
+isotropic Lorentzian (kappa) distribution. In this case, the filamentation
+instability growth rate can reach a maximum value markedly larger than that for
+a a plasma with a Maxwellian distribution function. This behaviour is opposite
+to what was observed for the Weibel instability growth rate in a bi-kappa
+plasma, which is always smaller than that obtained for a bi-Maxwellian plasma.
+The approach is further generalized for a counterstreaming plasma with a
+bi-kappa temperature anisotropy. In this case, the filamentation instability
+growth rate is enhanced by the Weibel effect when the plasma is hotter in the
+streaming direction, and the growth rate becomes even larger. These effects
+improve significantly the efficiency of the magnetic field generation, and
+provide further support for the potential role of the Weibel-type instabilities
+in the fast magnetization scenarios.",0802.0570v1
+2008-02-07,Large Scale Structure as a Probe of Gravitational Slip,"A new time-dependent, scale-independent parameter, \varpi, is employed in a
+phenomenological model of the deviation from General Relativity in which the
+Newtonian and longitudinal gravitational potentials slip apart on cosmological
+scales as dark energy, assumed to be arising from a new theory of gravitation,
+appears to dominate the universe. A comparison is presented between \varpi and
+other parameterized post-Friedmannian models in the literature. The effect of
+\varpi on the cosmic microwave background anisotropy spectrum, the growth of
+large scale structure, the galaxy weak-lensing correlation function, and
+cross-correlations of cosmic microwave background anisotropy with galaxy
+clustering are illustrated. Cosmological models with conventional maximum
+likelihood parameters are shown to find agreement with a narrow range of
+gravitational slip.",0802.1068v1
+2008-02-12,Giant orbital moments are responsible for the anisotropic magnetoresistance of atomic contacts,"We study here, both experimentally and theoretically, the anisotropy of
+magnetoresistance in atomic contacts. Our measurements on iron break junctions
+reveal an abrupt and hysteretic switch between two conductance levels when a
+large applied field is continuously rotated. We show that this behaviour stems
+from the coexistence of two metastable electronic states which result from the
+anisotropy of electronic interactions responsible for the enhancement of
+orbital magnetization. In both states giant orbital moments appear on the low
+coordinated central atom in a realistic contact geometry. However they differ
+by their orientation, parallel or perpendicular, with respect to the axis of
+the contact. Our explanation is totally at variance with the usual model based
+on the band structure of a monatomic linear chain, which we argue cannot be
+applied to 3d ferromagnetic metals.",0802.1595v1
+2008-02-12,Temperature dependent magnetization dynamics of magnetic nanoparticles,"Recent experimental and theoretical studies show that the switching behavior
+of magnetic nanoparticles can be well controlled by external time-dependent
+magnetic fields. In this work, we inspect theoretically the influence of the
+temperature and the magnetic anisotropy on the spin-dynamics and the switching
+properties of single domain magnetic nanoparticles (Stoner-particles). Our
+theoretical tools are the Landau-Lifshitz-Gilbert equation extended as to deal
+with finite temperatures within a Langevine framework. Physical quantities of
+interest are the minimum field amplitudes required for switching and the
+corresponding reversal times of the nanoparticle's magnetic moment. In
+particular, we contrast the cases of static and time-dependent external fields
+and analyze the influence of damping for a uniaxial and a cubic anisotropy.",0802.1740v1
+2008-02-14,Strain dependence of the Mn anisotropy in ferromagnetic semiconductors observed by x-ray magnetic circular dichroism,"We demonstrate sensitivity of the Mn 3d valence states to strain in the
+ferromagnetic semiconductors (Ga,Mn)As and (Al,Ga,Mn)As, using x-ray magnetic
+circular dichroism (XMCD). The spectral shape of the Mn $L_{2,3}$ XMCD is
+dependent on the orientation of the magnetization, and features with cubic and
+uniaxial dependence are distinguished. Reversing the strain reverses the sign
+of the uniaxial anisotropy of the Mn $L_3$ pre-peak which is ascribed to
+transitions from the Mn 2p core level to p-d hybridized valence band hole
+states. With increasing carrier localization, the $L_3$ pre-peak intensity
+increases, indicating an increasing 3d character of the hybridized holes.",0802.2061v1
+2008-02-18,Correlated Detection of sub-mHz Gravitational Waves by Two Optical-Fiber Interferometers,"Results from two optical-fiber gravitational-wave interferometric detectors
+are reported. The detector design is very small, cheap and simple to build and
+operate. Using two detectors has permitted various tests of the design
+principles as well as demonstrating the first simultaneous detection of
+correlated gravitational waves from detectors spatially separated by 1.1km. The
+frequency spectrum of the detected gravitational waves is sub-mHz with a strain
+spectral index a=-1.4 +/- 0.1. As well as characterising the wave effects the
+detectors also show, from data collected over some 80 days in the latter part
+of 2007, the dominant earth rotation effect and the earth orbit effect. The
+detectors operate by exploiting light speed anisotropy in optical-fibers. The
+data confirms previous observations of light speed anisotropy, earth rotation
+and orbit effects, and gravitational waves.",0802.2406v1
+2008-02-21,Damping by slow relaxing rare earth impurities in Ni80Fe20,"Doping NiFe by heavy rare earth atoms alters the magnetic relaxation
+properties of this material drastically. We show that this effect can be well
+explained by the slow relaxing impurity mechanism. This process is a
+consequence of the anisotropy of the on site exchange interaction between the
+4f magnetic moments and the conduction band. As expected from this model the
+magnitude of the damping effect scales with the anisotropy of the exchange
+interaction and increases by an order of magnitude at low temperatures. In
+addition our measurements allow us to determine the relaxation time of the 4f
+electrons as a function of temperature.",0802.3206v3
+2008-02-28,Anisotropic modification of the effective hole $g$-factor by electrostatic confinement,"We investigate effects of lateral confinement on spin splitting of energy
+levels in 2D hole gases grown on [311] GaAs. We found that lateral confinement
+enhances anisotropy of spin splitting relative to the 2D gas for both confining
+directions. Unexpectedly, the effective $g$-factor does not depend on the 1D
+energy level number $N$ for $B\|[0\bar{1}1]$ while it has strong $N$-dependence
+for $B\|[\bar{2}33]$. Apart from quantitative difference in the spin splitting
+of energy levels for the two orthogonal confinement directions we also report
+qualitative differences in the appearance of spin-split plateaus, with
+non-quantized plateaus observed only for the confinement in $[0\bar{1}1]$
+direction. In our samples we can clearly associate the difference with
+anisotropy of spin-orbit interactions.",0802.4271v1
+2008-03-02,Structural anisotropy of silica hydrogels prepared under magnetic field,"Birefringence measurements have been carried out on the Pb-doped silica
+hydrogels prepared under various magnetic fields up to 5T. The silica gels
+prepared at 5T were used as a medium of crystal growth of PbBr2, whose result
+implied the structural anisotropy; an aligned array of crystallites was
+obtained by transmission electron microscopy. While the samples prepared at 0,
+1, and 3T have no birefringence, we found that the samples have negative
+birefringence on the order of magnitude 10^-6 as if the direction of the
+magnetic field is the optic axis of a uniaxal crystal. To the authors'
+knowledge, the birefringent silica hydrogels were obtained by gelation under
+magnetic field for the first time. Also, scanning microscopic light scattering
+experiments have been performed. The results indicate that the characteristic
+length distribution for birefringent samples is narrower than that for
+non-birefringent ones.",0803.0114v2
+2008-03-06,Variational method study of the spin-1 Ising model with biaxial crystal-field anisotropy,"The phase diagram of the spin-1 Ising model in the presence of a biaxial
+crystal-field anisotropy is studied within the framework of a variational
+approach, based on the Bogolyubov inequality for the free energy. We have
+investigated the effects of a transverse crystal-field $D_{y}$ on the phase
+diagram in the $T-D_{x}$ plane. Results obtained by using effective-field
+theory (EFT) on the honeycomb (% $z=3$), square ($z=4$) and simple cubic
+($z=6$) lattices ($z$ is the coordination number) show only continuous phase
+transitions, while the variational approach presents first-order and continuous
+phase transitions for $D_{y}=0$% . We have also used the EFT for larger values
+of $z$ and we observe the presence of tricritical points in the phase diagrams,
+for $z\geq 7$, in accordance with the variational approach results.",0803.0934v1
+2008-03-31,Resolving Spacecraft Earth-Flyby Anomalies with Measured Light Speed Anisotropy,"Doppler shift observations of spacecraft, such as Galileo, NEAR, Cassini,
+Rosetta and MESSENGER in earth flybys, have all revealed unexplained speed
+`anomalies' - that the doppler-shift determined speeds are inconsistent with
+expected speeds. Here it is shown that these speed anomalies are not real and
+are actually the result of using an incorrect relationship between the observed
+doppler shift and the speed of the spacecraft - a relationship based on the
+assumption that the speed of light is isotropic in all frames, i.e. invariant.
+Taking account of the repeatedly measured light-speed anisotropy the anomalies
+are resolved. The Pioneer 10/11 anomalies are discussed, but not resolved. The
+spacecraft observations demonstrate again that the speed of light is not
+invariant, and is isotropic only with respect to a dynamical 3-space. The
+existing doppler shift data also offers a resource to characterise a new form
+of gravitational waves, the dynamical 3-space turbulence, that has also been
+detected by other techniques.",0804.0039v4
+2008-04-07,Fast rotating condensates in an asymmetric harmonic trap,"We investigate the effect of the anisotropy of a harmonic trap on the
+behaviour of a fast rotating Bose-Einstein condensate. Fast rotation is reached
+when the rotational velocity is close to the smallest trapping frequency,
+thereby deconfining the condensate in the corresponding direction. A striking
+new feature is the non-existence of visible vortices for the ground state. The
+condensate can be described with the lowest Landau level set of states, but
+using distorted complex coordinates. We find that the coarse grained atomic
+density behaves like an inverted parabola with large radius in the deconfined
+direction, and like a fixed Gaussian in the other direction. It has no visible
+vortices, but invisible vortices which are needed to recover the mixed
+Thomas-Fermi Gaussian profile. There is a regime of small anisotropy and
+intermediate rotational velocity where the behaviour is similar to the
+isotropic case: a hexagonal Abrikosov lattice of vortices, with an inverted
+parabola profile.",0804.0971v3
+2008-04-08,Transition metal dimers as potential molecular magnets: A challenge to computational chemistry,"Dimers are the smallest chemical objects that show magnetic anisotropy. We
+focus on 3$d$ and 4$d$ transition metal dimers that have magnetic ground states
+in most cases. Some of these magnetic dimers have a considerable barrier
+against re-orientation of their magnetization, the so-called magnetic
+anisotropy energy, MAE. The height of this barrier is important for
+technological applications, as it determines, e.g., the stability of
+information stored in magnetic memory devices. It can be estimated by means of
+relativistic density functional calculations. Our approach is based on a
+full-potential local-orbital method (FPLO) in a four-component Dirac-Kohn-Sham
+implementation. Orbital polarization corrections to the local density
+approximation are employed. They are discussed in the broader context of
+orbital dependent density functionals. Ground state properties (spin
+multiplicity, bond length, harmonic vibrational frequency, spin- and orbital
+magnetic moment, and MAE) of the 3$d$ and 4$d$ transition metal dimers are
+evaluated and compared with available experimental and theoretical data. We
+find exceptionally high values of MAE, close to 0.2 eV, for four particular
+dimers: Fe$_2$, Co$_2$, Ni$_2$, and Rh$_2$.",0804.1233v1
+2008-04-16,Dilepton production as a measure of QGP thermalization time,"We discuss dilepton production from a quark-gluon plasma which has a
+time-dependent anisotropy in momentum space. A phenomenological model for the
+hard momentum scale, p_hard(tau) and the plasma anisotropy parameter, xi(tau),
+is presented. The model interpolates between early-time 1+1 free streaming
+behavior (tau << tau_iso) and late-time ideal 1+1 hydrodynamical behavior (tau
+>> tau_iso). Using this model, we find that the dilepton rate arising from
+electromagnetic annihilations of quarks in the kinematic range 3 <p_T< 8 GeV is
+sensitive to the assumed isotropization time of the system, tau_iso. Therefore
+high-energy dilepton production can be used to probe the degree of
+momentum-space isotropy of a quark-gluon plasma produced in relativistic heavy
+ion collisions and the time of onset of hydrodynamic expansion of the QGP.",0804.2618v1
+2008-04-17,"Effective-medium theory for infinite-contrast, 2D-periodic, linear composites with strongly anisotropic matrix behavior: dilute limit and cross-over behavior","The overall behavior of a 2D lattice of voids embedded in an anisotropic
+matrix is investigated in the limit of vanishing porosity f. An
+effective-medium model (of the Hashin-Shtrikman type) which accounts for
+elastic interactions between neighboring voids, is compared to Fast Fourier
+Transform numerical solutions and, in the limits of infinite anisotropy, to
+exact results. A cross-over between regular and singular dilute regimes is
+found, driven by a characteristic length which depends on f and on the
+anisotropy strength. The singular regime, where the leading dilute correction
+to the elastic moduli is an O(f^{1/2}), is related to strain localization and
+to change in character - from elliptic to hyperbolic - of the governing
+equations.",0804.2817v1
+2008-04-18,Dzyaloshinsky-Moriya Anisotropy in the Spin-1/2 Kagomé Compound ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$,"We report the determination of the Dzyaloshinsky-Moriya interaction, the
+dominant magnetic anisotropy term in the \kagome spin-1/2 compound {\herbert}.
+Based on the analysis of the high-temperature electron spin resonance (ESR)
+spectra, we find its main component $|D_z|=15(1)$ K to be perpendicular to the
+\kagome planes. Through the temperature dependent ESR line-width we observe a
+building up of nearest-neighbor spin-spin correlations below $\sim$150 K.",0804.3107v2
+2008-04-21,Anisotropic plasmons in a two-dimensional electron gas with spin-orbit interaction,"Spin-orbit coupling induced anisotropies of plasmon dynamics are investigated
+in two-dimensional semiconductor structures. The interplay of the linear
+Bychkov-Rashba and Dresselhaus spin-orbit interactions drastically affects the
+plasmon spectrum: the dynamical structure factor exhibits variations over
+several decades, prohibiting plasmon propagation in specific directions. While
+this plasmon filtering makes the presence of spin-orbit coupling in plasmon
+dynamics observable, it also offers a control tool for plasmonic devices.
+Remarkably, if the strengths of the two interactions are equal, not only the
+anisotropy, but all the traces of the linear spin-orbit coupling in the
+collective response disappear.",0804.3366v3
+2008-04-25,Evolution of the Kondo state of YbRh2Si2 probed by high field ESR,"An electron spin resonance (ESR) study of the heavy fermion compound YbRh2Si2
+for fields up to ~ 8 T reveals a strongly anisotropic signal below the single
+ion Kondo temperature T_K ~ 25 K. A remarkable similarity between the
+T-dependence of the ESR parameters and that of the specific heat and the 29Si
+nuclear magnetic resonance data gives evidence that the ESR response is given
+by heavy fermions which are formed below T_K and that ESR properties are
+determined by their field dependent mass and lifetime. The signal anisotropy,
+otherwise typical for Yb{3+} ions, suggests that, owing to a strong
+hybridization with conduction electrons at T < T_K, the magnetic anisotropy of
+the 4f states is absorbed in the ESR of heavy quasiparticles. Tuning the Kondo
+effect on the 4f states with magnetic fields ~ 2 - 8 T and temperature 2 - 25 K
+yields a gradual change of the ESR g-factor and linewidth which reflects the
+evolution of the Kondo state in this Kondo lattice system.",0804.4105v2
+2008-05-06,Kleinberg navigation on anisotropic lattices,"We study the Kleinberg problem of navigation in Small World networks when the
+underlying lattice is stretched along a preferred direction. Extensive
+simulations confirm that maximally efficient navigation is attained when the
+length $r$ of long-range links is taken from the distribution $P({\bf r})\sim
+r^{-\alpha}$, when the exponent $\alpha$ is equal to 2, the dimension of the
+underlying lattice, regardless of the amount of anisotropy, but only in the
+limit of infinite lattice size, $L\to\infty$. For finite size lattices we find
+an optimal $\alpha(L)$ that depends strongly on $L$. The convergence to
+$\alpha=2$ as $L\to\infty$ shows interesting power-law dependence on the
+anisotropy strength.",0805.0807v1
+2008-05-09,New Anomalies in Cosmic Microwave Background Anisotropy: Violation of the Isotropic Gaussian Hypothesis in Low-$l$ Modes,"In the standard framework of cosmology, primordial density fluctuations are
+assumed to have an isotropic Gaussian distribution. We search for deviations
+from this assumption in the WMAP data for the low $l$ modes of Cosmic Microwave
+Background Anisotropies (CMBA), by studying the directions of the z-axis that
+maximize the $l=m$ modes and the resulting amplitudes of these modes. We find a
+general alignment of the directions for $l=2$ to 10 modes to within 1/4 of the
+northern hemisphere. This alignment can be regarded as a generalization of the
+recently discovered alignment of the $l=2$ and 3 modes - the so-called `Axis of
+Evil'. Furthermore, we find abnormally high (low) powers in the $l=m=6$, 12 -
+17 ($l=m=5$) modes; the probabilities for having the anomalous amplitudes of
+the $l=m=5$, 6, 17 modes are about 0.1%, 1% and 1% respectively according to
+the Gaussian conjecture. The alignment and anomalous amplitudes for these low
+$l$ modes are very robust against foreground contamination or different
+cleaning strategies, suggesting a cosmological origin and possibly supporting a
+non-standard inflation.",0805.1316v2
+2008-05-12,Exchange coupled perpendicular media,"The potential of exchange spring bilayers and graded media is reviewed. An
+analytical model for the optimization of graded media gives an optimal value of
+the magnetic polarization of Js = 0.8 T. The optimum design allows for
+thermally stable grains with grain diameters in the order of 3.3 nm, which
+supports ultra high density up to 5 to 10 Tbit per inch2. The switching field
+distribution is significantly reduced in bilayer media and graded media
+compared to single phase media. For the graded media the switching field
+distribution is reduced by about a factor of two. For bilayer media the minimum
+switching field distribution is obtained for soft layer anisotropies about one
+fifth of the hard layer anisotropy. The influence of precessional switching on
+the reversal time and the reversal field is investigated in detail for magnetic
+bilayers. Exchange spring bilayers can be reversed with field pulses of 20 ps.",0805.1674v1
+2008-05-21,Exploring the order parameter symmetry of p-wave Fermi condensates,"We discuss the time-of-flight expansion of dilute p-wave Fermi condensates on
+the BEC side of Feshbach resonances, as a way to extract information about the
+order parameter symmetry for superfluidity. We show that the cloud profile is
+in general sensitive to the interaction strength between fermions, the
+magnitude and direction of external magnetic fields, and to the angular
+momentum projection of the order parameter. In particular, due to the
+anisotropic nature of p-wave interactions we show that the time-of-flight
+expansion of a p-wave superfluid is anisotropic even if the superfluid is
+confined to a completely isotropic trap, unlike the case of Bose or s-wave
+Fermi condensates, which under the same circumstances expand isotropically.
+Furthermore, we demonstrate that expanding p-wave superfluids released from
+axially symmetric traps experience anisotropy inversions, where the aspect
+ratio between the axial and radial directions change during expansion, while
+the axial symmetry can also be lost reflecting the spatial anisotropy of the
+underlying interaction.",0805.3315v1
+2008-05-22,Repeated magnetic compensation behaviour in Nd0.75Gd0.25Rh3B2 alloy having hexagonal structure and planar anisotropy,"The results of dc and ac magnetization, electrical resistance and heat
+capacity studies in an admixed rare earth alloy Nd0.75Gd0.25Rh3B2, which is
+close to the zero magnetization limit, are reported. Novel observations include
+the two antiferromagnetic like transitions, concomitant repeated/multiple
+magnetic compensation behaviour and a characteristic oscillatory magnetic
+response, with temperature dependence of magnetization at low fields crossing
+the M = 0 axis thrice. The effective coercive field relating to the residual
+remanence also has an oscillatory response, with two minima located close to
+two zero-crossover temperatures. The unusual behavior in Nd0.75Gd0.25Rh3B2 is
+conjectured to arise from its anisotropic hexagonal structure, with planar
+anisotropy, resulting in a quasi one dimensional electronic structure and the
+accentuated role of conduction electron polarization near the zero
+magnetization limit.",0805.3412v2
+2008-05-22,Cosmic Microwave Background Anisotropy from Nonlinear Structures in Accelerating Universes,"We study the cosmic microwave background (CMB) anisotropy due to spherically
+symmetric nonlinear structures in flat universes with dust and a cosmological
+constant. By modeling a time-evolving spherical compensated void/lump by
+Lemaitre-Tolman-Bondi spacetimes, we numerically solve the null geodesic
+equations with the Einstein equations. We find that a nonlinear void redshifts
+the CMB photons that pass through it regardless of the distance to it. In
+contrast, a nonlinear lump blueshifts (or redshifts) the CMB photons if it is
+located near (or sufficiently far from) us. The present analysis
+comprehensively covers previous works based on a thin-shell approximation and a
+linear/second order perturbation method and the effects of shell thickness and
+full nonlinearity. Our results indicate that, if quasi-linear and large
+($>100$Mpc) voids/lumps would exist, they could be observed as cold or hot
+spots with temperature variance $>10^{-5}$K in the CMB sky.",0805.3446v2
+2008-05-27,System size and beam energy dependence of azimuthal anisotropy from PHENIX,"We present azimuthal anisotropy measurements in Au+Au and Cu+Cu collisions at
+$\sqrt{s_{NN}}$ = 62.4 and 200 GeV. Comparison between reaction plane and
+cumulant $v_2$ measurements in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
+show that non-flow contributions, originating mainly from jets, influence the
+extracted $v_2$ for $p_T$ $\gtrsim$ 3.5 GeV/c. Number of constituent quark
+(NCQ) scaling of $v_2$, when studied as a function of transverse kinetic energy
+$KE_T$, is seen to hold for Au+Au collisions at $\sqrt{s_{NN}}$ = 62.4 and 200
+GeV and for Cu+Cu collisions at $\sqrt{s_{NN}}$ = 200 GeV for $KE_{T}$
+$\lesssim$ 1 GeV/c. Differential hexadecupole flow $v_4$ seems to exhibit
+scaling with integral $v_2$ for centrality $\le$ 40% as has been observed for
+differential $v_2$.",0805.4039v1
+2008-05-29,Band structure of ZnO from resonant x-ray emission spectroscopy,"Soft x-ray emission and absorption spectroscopy of the O K-edge are employed
+to investigate the electronic structure of wurtzite ZnO(0001). A quasiparticle
+band structure calculated within the GW approximation agrees well with the
+data, most notably with the energetic location of the Zn3d - O2p hybridized
+state and the anisotropy of the absorption spectra. Dispersion in the band
+structure is mapped using the coherent k-selective part of the resonant x-ray
+emission spectra. We show that a more extensive mapping of the bands is
+possible in the case of crystalline anisotropy such as that found in ZnO.",0805.4641v3
+2008-06-05,Anisotropy of superconducting single crystal SmFeAsO_(0.8)F_(0.2) studied by torque magnetometry,"Single crystals of the oxypnictide superconductor SmFeAsO_(0.8)F_(0.2) with
+T_c=45(1) K were investigated by torque magnetometry. The crystals of mass~0.1
+mug were grown by a high-pressure cubic anvil technique. The use of a
+high-sensitive piezoresistive torque sensor made it possible to study the
+anisotropic magnetic properties of these tiny crystals. The anisotropy
+parameter was found to be field independent, but varies strongly with
+temperature ranging from 8 at T=T_c to 23 at T=0.4T_c. This unusual behavior
+signals unconventional superconductivity.",0806.1024v3
+2008-06-07,Influence of quenched jets on di-hadron correlations,"A simple jet absorption model is used to study the influence of hadron pairs
+produced by quenched jets, on di-hadron angular correlations at intermediate
+transverse momentum ($p_T$). We demonstrate that such pairs can dominate both
+the yield and the shape of angular correlations, and may account for the
+similar properties between the near-side ""ridge"" and the away-side
+""double-humped"" structure seen in recent data. These hadron pairs also show
+azimuthal anisotropy which is sensitive to the emission angle of hadrons
+relative to that of the jet. Measurement of this anisotropy may provide a
+constraint for elucidating the production mechanism for near- and away-side
+hadron pairs at intermediate $p_T$.",0806.1225v3
+2008-06-12,Neutrino mass effects on vector and tensor CMB anisotropies in the presence of a primordial magnetic field,"If a primordial magnetic field (PMF) is present during photon decoupling and
+afterward, a finite neutrino mass can affect all modes of the CMB. In this
+work, we expand on earlier studies of the scalar mode effects by constructing
+the vector and tensor mode equations in the presence of massive neutrinos and a
+PMF. We compute the power spectrum of the various modes in an illustrative
+example and find that the neutrino mass can significantly affect the vector and
+tensor modes when a PMF exists, while the effects are negligible for no PMF.
+The most prominent result of the present analysis is the behavior of the EE
+component of the tensor mode at low multipoles. For massive neutrinos the EE
+mode can become comparable to the observed primary anisotropy. Therefore, if
+and when the EE mode power spectrum is measured at low multipoles the
+possibility exists to place a strong constraint on the sum of the neutrino
+masses.",0806.2018v1
+2008-06-13,Topological defects in antiferromagnetically coupled multilayers with perpendicular anisotropy,"A rich variety of specific multidomain textures recently observed in
+antiferromagnetically coupled multilayers with perpendicular anisotropy include
+regular (equilibrium) multidomain states as well as different types of
+topological magnetic defects. Within a phenomenological theory we have
+classified and analyzed the possible magnetic defects in the antiferromagnetic
+ground state and determine their structures. We have derived the optimal sizes
+of the defects as functions of the antiferromagnetic exchange, the applied
+magnetic field, and geometrical parameters of the multilayer. The calculated
+magnetic phase diagrams show the existence regions for all types of magnetic
+defects. Experimental investigations of the remanent states (observed after
+different magnetic pre-history) in [Co/Pt]/Ru multilayers with wedged Co layers
+reveal a corresponding succession of different magnetic defect domain types.",0806.2170v2
+2008-06-22,Determination of the exchange anisotropy in perovskite antiferromagnets using powder inelastic neutron scattering,"A procedure is outlined for the determination of magnetic exchange constants
+in anisotropic perovskite anitferromagnets using powder inelastic neutron
+scattering. Spin wave densities-of-states are measured using time-of-flight
+inelastic neutron scattering for LaMnO$_{3}$ ($A$-type antiferromagnet),
+LaVO$_{3}$ ($C$-type), and LaFeO$_{3}$ ($G$-type) and compared to Heisenberg
+model calculations. The anisotropy of in-plane ($J_{ab}$) and out-of-plane
+($J_{c}$) exchange constants can be obtained from the data. The procedure
+quickly determines the magnetic exchange interactions without the need for
+single-crystal dispersion measurements and allows for rapid systematic studies
+of the evolution of magnetism in perovskite systems.",0806.3576v1
+2008-06-27,Statistical and systematical errors in cosmic microwave background maps,"Sky temperature map of the cosmic microwave background (CMB) is one of the
+premier probes of cosmology. To minimize instrumentally induced systematic
+errors, CMB anisotropy experiments measure temperature differences across the
+sky using paires of horn antennas with a fixed separation angle, temperature
+maps are recovered from temperature differences obtained in sky survey through
+a map-making procedure. The instrument noise, inhomogeneities of the sky
+coverage and sky temperature inevitably produce statistical and systematical
+errors in recovered temperature maps. We show in this paper that
+observation-dependent noise and systematic temperature distortion contained in
+released Wilkinson Microwave Anisotropy Probe (WMAP) CMB maps are remarkable.
+These errors can contribute to large-scale anomalies detected in WMAP maps and
+distort the angular power spectrum as well. It is needed to remake temperature
+maps from original WMAP differential data with modified map-making procedure to
+avoid observation-dependent noise and systematic distortion in recovered maps.",0806.4493v1
+2008-07-02,Numerical Studies of Quantum Hall Ferromagnetism in Two-Subband Systems,"We carry out a numerical study of the quantum Hall ferromagnetism in a
+two-subband system using a set of experimental parameters in a recently
+experiment [X. C. Zhang, I. Martin, and H. W. Jiang, Phys. Rev. B \textbf{74},
+073301 (2006)]. Employing the self-consistence local density approximation for
+growth direction wave function and the Hartree-Fock theory for the pseudospin
+anisotropy energy, we are able to account for the easy-axis and easy-plane
+quantum Hall ferromagnetism observed at total filling factor $\nu = 3$ and
+$\nu= 4$, respectively. Our study provides some insight of how the anisotropy
+energy, which highly depends upon the distribution of growth direction wave
+functions, determines the symmetry of the quantum Hall ferromagnets.",0807.0297v1
+2008-07-02,Cosmic microwave background bispectrum on small angular scales,"This article investigates the non-linear evolution of cosmological
+perturbations on sub-Hubble scales in order to evaluate the unavoidable
+deviations from Gaussianity that arise from the non-linear dynamics. It shows
+that the dominant contribution to modes coupling in the cosmic microwave
+background temperature anisotropies on small angular scales is driven by the
+sub-Hubble non-linear evolution of the dark matter component. The perturbation
+equations, involving in particular the first moments of the Boltzmann equation
+for the photons, are integrated up to second order in perturbations. An
+analytical analysis of the solutions gives a physical understanding of the
+result as well as an estimation of its order of magnitude. This allows to
+quantify the expected deviation from Gaussianity of the cosmic microwave
+background temperature anisotropy and, in particular, to compute its bispectrum
+on small angular scales. Restricting to equilateral configurations, we show
+that the non-linear evolution accounts for a contribution that would be
+equivalent to a constant primordial non-Gaussianity of order fNL~25 on scales
+ranging approximately from l~1000 to l~3000.",0807.0341v2
+2008-07-04,"Strain-Control of the magnetic anisotropy in (Ga,Mn)(As,P) ferromagnetic semiconductor layers","A small fraction of phosphorus (up to 10 %) was incorporated in ferromagnetic
+(Ga,Mn)As epilayers grown on a GaAs substrate. P incorporation allows reducing
+the epitaxial strain or even change its sign, resulting in strong modifications
+of the magnetic anisotropy. In particular a reorientation of the easy axis
+toward the growth direction is observed for high P concentration. It offers an
+interesting alternative to the metamorphic approach, in particular for
+magnetization reversal experiments where epitaxial defects stongly affect the
+domain wall propagation.",0807.0748v1
+2008-07-04,Polarization-Mixing in Optical Lattices with Uniaxial Anisotropy,"We study optical excitations of an ultracold gas in an optical lattice in the
+Mott insulator case and with anisotropic properties. The anisotropy is induced
+by an oriented transition dipole generated by optical pumping and external
+static fields, and is of the type of uniaxial crystals. Within a cavity, the
+electronic excitations and the cavity photons of both TE and TM polarizations
+are coherently mixed to form two polariton branches. Also a photonic branch
+appears which decouples from the electronic transitions. The photon
+polarization mixing can be observed by linear optical spectra. For example, for
+an incident field of TE polarization we obtain TE and TM transmitted and
+reflected fields. Also we calculate the phase shift in the TE and TM
+transmitted and reflected fields relative to the incident field phase, which
+lead to polarization rotations.",0807.0761v1
+2008-07-08,Semiclassical spin liquid state of easy axis Kagome antiferromagnets,"Motivated by recent experiments on Nd-langasite, we consider the effect of
+strong easy axis single-ion anisotropy $D$ on $S > 3/2$ spins interacting with
+antiferromagnetic exchange $J$ on the Kagome lattice. When $T \ll DS^2$, the
+collinear low energy states selected by the anisotropy map on to configurations
+of the classical Kagome lattice Ising antiferromagnet. However, the low
+temperature limit is quite different from the cooperative Ising paramagnet that
+obtains classically for $T \ll JS^2$. We find that sub-leading ${\mathcal
+O}(J^3S/D^2)$ multi-spin interactions arising from the transverse quantum
+dynamics result in a crossover from an intermediate temperature classical
+cooperative Ising paramagnet to a semiclassical spin liquid with distinct
+short-ranged correlations for $T \ll J^3S/D^2$.",0807.1163v1
+2008-07-08,Revealing dark matter substructure with anisotropies in the diffuse gamma-ray background,"The majority of gamma-ray emission from Galactic dark matter annihilation is
+likely to be detected as a contribution to the diffuse gamma-ray background. I
+show that dark matter substructure in the halo of the Galaxy induces
+characteristic anisotropies in the diffuse background that could be used to
+determine the small-scale dark matter distribution. I calculate the angular
+power spectrum of the emission from dark matter substructure for several models
+of the subhalo population, and show that features in the power spectrum can be
+used to infer the presence of substructure. The shape of the power spectrum is
+largely unaffected by the subhalo radial distribution and mass function, and
+for many scenarios I find that a measurement of the angular power spectrum by
+Fermi will be able to constrain the abundance of substructure. An anti-biased
+subhalo radial distribution is shown to produce emission that differs
+significantly in intensity and large-scale angular dependence from that of a
+subhalo distribution which traces the smooth dark matter halo, potentially
+impacting the detectability of the dark matter signal for a variety of targets
+and methods.",0807.1328v2
+2008-07-09,"Molecular Beam Epitaxy grown (Ga,Mn)(As,P) with perpendicular to plane magnetic easy axis","We present an experimental investigation of the magnetic, electrical and
+structural properties of Ga0.94Mn0.06As1-yPy layers grown by molecular beam
+epitaxy on GaAs substrates for y less than or equal to 0.3. X-ray diffraction
+measurements reveal that the layers are under tensile strain which gives rise
+to a magnetic easy axis perpendicular to the plane of the layers. The strength
+of the magnetic anisotropy and the coercive field increase as the phosphorous
+concentration is increased. The resistivity of all samples shows metallic
+behaviour with the resistivity increasing as y increases. These materials will
+be useful for studies of micromagnetic phenomena requiring metallic
+ferromagnetic material with perpendicular magnetic anisotropy.",0807.1469v1
+2008-07-15,Constraints on Kinetically Modified Inflation from WMAP5,"Single field inflationary models with a non-minimal kinetic term (also called
+k-inflationary models) can be characterised by the so-called sound flow
+functions, which complete the usual Hubble flow hierarchy. These parameters
+appear in the primordial power spectra of cosmological perturbations at leading
+order and, therefore, affect the resulting Cosmic Microwave Background (CMB)
+anisotropies. Using the fifth year Wilkinson Microwave Anisotropy Probe (WMAP5)
+data, we derive the marginalised posterior probability distributions for both
+the sound and Hubble flow parameters. In contrast to the standard situation,
+these parameters remain separately unbounded, and notably there is no longer
+any upper limit on epsilon_1, the first Hubble flow function. Only special
+combinations of these parameters, corresponding to the spectral index and
+tensor-to-scalar ratio observables, are actually constrained by the data. The
+energy scale of k-inflation is nevertheless limited from above to Hinf/mpl <
+6x10^(-6) at two-sigma level. Moreover, for the sub-class of Dirac-Born-Infeld
+models, by considering the non-gaussianity bounds on the sound speed, we find a
+weak limit epsilon_1 < 0.08 at 95% confidence level.",0807.2414v1
+2008-07-17,Symmetry of standing waves generated by a point defect in epitaxial graphene,"Using scanning tunneling microscopy (STM) and Fourier Transform STM (FT-STM),
+we have studied a point defect in an epitaxial graphene sample grown on silicon
+carbide substrate. This analysis allows us to extract the quasiparticle energy
+dispersion, and to give a first experimental proof of the validity of Fermi
+liquid theory in graphene for a wide range of energies from -800 meV to +800
+meV. We also find evidence of a strong threefold anisotropy in the standing
+waves generated by the defect. We discuss possible relations between this
+anisotropy, the chirality of the electrons, and the asymmetry between
+graphene's two sublattices. All experimental measurements are compared and
+related to theoretical T-matrix calculations.",0807.2813v1
+2008-07-22,Exponential equilibration by slow cooling in the planar random-anisotropy magnet: experiments and simulations,"Neutron measurements of the equilibration of the staggered magnetization in
+DyAs(0.35)V(0.65)O4 are compared with Monte Carlo simulations of spin dynamics
+in a planar random-anisotropy magnet. The simulation results are in agreement
+with striking observed relaxation phenomena: when cooled rapidly to a low
+temperature no magnetic ordering is observed, but when cooled in small steps an
+ordered magnetic moment appears which is found to equilibrate exponentially
+with time at temperatures through and below the transition temperature. In
+contrast to the freezing of spins in other random systems, the time scale of
+the relaxation in this system does not increase significantly even at the
+lowest temperatures.",0807.3536v1
+2008-07-23,Large Scale Plane-Mirroring in the Cosmic Microwave Background WMAP5 Maps,"We continue investigation of the hidden plane-mirror symmetry in the
+distribution of excursion sets in cosmic microwave background (CMB) temperature
+anisotropy maps, previously noticed in the three-year data of the Wilkinson
+microwave anisotropy probe (WMAP), using the WMAP 5 years maps. The symmetry is
+shown to have higher significance, \chi^2 < 1.7, for low multipoles \ell < 5,
+while disappearing at larger multipoles, \chi^2 > 3.5 for \ell > 10. The study
+of the sum and difference maps of temperature inhomogeneity regions, along with
+simulated maps, confirms its existence.The properties of these mirroring
+symmetries are compatible with those produced by the Sachs-Wolfe effect in the
+presence of an anomalously large component of horizon-size density
+perturbations, independent of one of the spatial coordinates, and/or a
+slab-like spatial topology of the Universe.",0807.3652v2
+2008-07-23,Single-valley high-mobility (110) AlAs quantum wells with anisotropic mass,"We studied a doping series of (110)-oriented AlAs quantum wells (QWs) and
+observed transport evidence of single anisotropic-mass valley occupancy for the
+electrons in a 150 \AA wide QW. Our calculations of strain and quantum
+confinement for these samples predict single anisotropic-mass valley occupancy
+for well widths $W$ greater than 53 \AA. Below this, double-valley occupation
+is predicted such that the longitudinal mass axes are collinear. We observed
+mobility anisotropy in the electronic transport along the crystallographic
+directions in the ratio of 2.8, attributed to the mass anisotropy as well as
+anisotropic scattering of the electrons in the X-valley of AlAs.",0807.3763v1
+2008-07-25,Caloric Determination of the Upper Critical Fields and Anisotropy of NdFeAsO1-xFx Single Crystals,"We present heat capacity measurements of the upper critical fields of
+single-crystal NdFeAsO1-xFx. In zero-magnetic field a clear step in the heat
+capacity is observed at Tc = 47K . In fields applied perpendicular to the
+FeAs-layers the step broadens significantly whereas for the in-plane
+orientation the field effects are small. This behavior is reminiscent of the
+CuO2-high-Tc superconductors and is a manifestation of pronounced fluctuation
+effects. Using an entropy conserving construction we determine the transition
+temperatures in applied fields and the upper critical field slopes of dHc2,a =
+-0.72 T/K and dHc2,ab = -3.1 T/K. Zero-temperature coherence lengths of xiab =
+3.7 nm and xic = 0.9 nm and a modest superconducting anisotropy of gamma ~ 4
+can be deduced in a single-band model.",0807.4196v1
+2008-07-28,Determination of anisotropic Hc2 up to 60 T in (Ba0.55K0.45)Fe2As2 single crystals,"The radio frequency penetration depth was measured in the superconductor
+(Ba$_{0.55}$K$_{0.45}$)Fe$_{2}$As$_{2}$ under pulsed magnetic fields extending
+to 60 tesla and down to 14 K. Using these data we are able to infer a
+$H_{c2}(T)$, $H-T$ phase diagram, for applied fields parallel and perpendicular
+to the crystallographic c-axis. The upper critical field curvature is different
+for the respective orientations but they each remain positive down to 14 K. The
+upper critical field anisotropy is moderate, $\approx 3.5$ close to $T_c$, and
+drops with the decrease of temperature, reaching $\approx 1.2$ at $14 K$. These
+data and analysis indicate that (i) (Ba$_{0.55}$K$_{0.45}$)Fe$_{2}$As$_{2}$
+anisotropy diminishes with temperature and has an unusual temperature
+dependence, (ii) $H_{c2} (T=0)$ for this compound may easily approach fields of
+75 tesla.",0807.4488v3
+2008-07-30,LRS Bianchi Type I Models with Anisotropic Dark Energy and Constant Deceleration Parameter,"Locally rotationally symmetric (LRS) Bianchi Type I cosmological models are
+examined in the presence of dynamically anisotropic dark energy and perfect
+fluid. We assume that the dark energy (DE) is minimally interacting, has
+dynamical energy density, anisotropic equation of state parameter (EoS). The
+conservation of the energy-momentum tensor of the DE is assumed to consist of
+two separately additive conserved parts. A special law is assumed for the
+deviation from isotropic EoS, which is consistent with the assumption on the
+conservation of the energy-momentum tensor of the DE. Exact solutions of
+Einstein's field equations are obtained by assuming a special law of variation
+for the mean Hubble parameter, which yields a constant value of the
+deceleration parameter. Geometrical and kinematic properties of the models and
+the behaviour of the anisotropy of the dark energy has been carried out. The
+models give dynamically anisotropic expansion history for the universe that
+allows to fine tune the isotropization of the Bianchi metric, hence the CMB
+anisotropy.",0807.4867v2
+2008-07-31,GaN/AlN Quantum Dots for Single Qubit Emitters,"We study theoretically the electronic properties of $c$-plane GaN/AlN quantum
+dots (QDs) with focus on their potential as sources of single polarized photons
+for future quantum communication systems. Within the framework of eight-band
+k.p theory we calculate the optical interband transitions of the QDs and their
+polarization properties. We show that an anisotropy of the QD confinement
+potential in the basal plane (e.g. QD elongation or strain anisotropy) leads to
+a pronounced linear polarization of the ground state and excited state
+transitions. An externally applied uniaxial stress can be used to either induce
+a linear polarization of the ground-state transition for emission of single
+polarized photons or even to compensate the polarization induced by the
+structural elongation.",0807.5024v2
+2008-07-31,Wind anisotropy and stellar evolution,"Mass loss is a determinant factor which strongly affects the evolution and
+the fate of massive stars. At low metallicity, stars are supposed to rotate
+faster than at the solar one. This favors the existence of stars near the
+critical velocity. In this rotation regime, the deformation of the stellar
+surface becomes important, and wind anisotropy develops. Polar winds are
+expected to be dominant for fast rotating hot stars.
+  These polar winds allow the star to lose large quantities of mass and still
+retain a high angular momentum, and they modifie the evolution of the surface
+velocity and the final angular momentum kept in the star's core. We show here
+how these winds affect the final stages of massive stars, according to our
+knowledge about Gamma Ray Bursts. Computation of theoretical Gamma Ray Bursts
+rate indicates that our models have too fast rotating cores, and that we need
+to include an additional effect to spin them down. Magnetic fields in stars act
+in this direction, and we show how they modify the evolution of massive star up
+to the final stages.",0807.5061v1
+2008-08-21,First Measurement of the J/psi Azimuthal Anisotropy in PHENIX at Forward Rapidity in Au+Au Collisions at sqrt s(NN) = 200 GeV,"The PHENIX experiment has shown that J/psis are suppressed in central Au+Au
+collisions at a center of mass energy per nucleon-nucleon collision sqrt s(NN)
+= 200 GeV, and that the suppression is larger at forward than at mid-rapidity.
+Part of this difference may be explained by cold nuclear matter effects but the
+most central collisions suggest that regeneration mechanisms could be at play.
+In 2007, PHENIX collected almost four times more Au+Au collisions at this
+energy than used for previous published results. Moreover, the addition of a
+new reaction plane detector allows a much better analysis of the J/psi behavior
+in the azimuthal plane. Since a large elliptic flow has been measured for open
+charm, measuring J/psi azimuthal anisotropies may give a hint if J/psi are
+recombined in the expanding matter. First PHENIX results of J/psi elliptic flow
+as a function of transverse momentum at forward rapidity are presented in this
+article. The analysis is detailed and results are compared to mid-rapidity
+PHENIX preliminary results as well as to predictions.",0808.2925v2
+2008-08-28,Suppression of forward dilepton production from an anisotropic quark-gluon plasma,"We calculate the rapidity dependence of leading-order medium dilepton yields
+resulting from a quark-gluon plasma which has a local time-dependent anisotropy
+in momentum space. We present a phenomenological model which includes temporal
+evolution of the plasma anisotropy parameter, xi, and the hard momentum scale,
+p_hard. Our model interpolates between 1+1 dimensional collisionally-broadened
+expansion at early times and 1+1 dimensional ideal hydrodynamic expansion at
+late times. Using our model, we find that at LHC energies, forward high-energy
+medium dilepton production would be suppressed by up to a factor of 3 if one
+assumes an isotropization/thermalization time of 2 fm/c. Therefore, it may be
+possible to use forward dilepton yields to experimentally determine the time of
+onset of locally isotropic hydrodynamic expansion of the quark-gluon plasma as
+produced in ultrarelativistic heavy-ion collisions.",0808.3969v1
+2008-09-04,The dynamical structure of dark matter halos with universal properties,"$N$-body simulations have unveiled several apparently universal properties of
+dark matter halos, including a cusped density profile, a power-law pseudo
+phase-space density $\rho/\sigma_r^3$, and a linear $\beta-\gamma$ relation
+between the density slope and the velocity anisotropy. We present a family of
+self-consistent phase-space distribution functions $F(E,L)$, based on the
+Dehnen-McLaughlin Jeans models, that incorporate these universal properties
+very accurately. These distribution functions, derived using a quadratic
+programming technique, are analytical, positive and smooth over the entire
+phase space and are able to generate four-parameter velocity anisotropy
+profiles $\beta(r)$ with arbitrary asymptotic values $\beta_0$ and
+$\beta_\infty$. We discuss the orbital structure of six radially anisotropic
+systems in detail and argue that, apart from its use for generating initial
+conditions for $N$-body studies, our dynamical modeling provides a valuable
+complementary approach to understand the processes involved in the formation of
+dark matter halos.",0809.0901v1
+2008-09-15,Role of covalent Fe-As bonding in the magnetic moment formation and exchange mechanisms in iron-pnictide superconductors,"The electronic origin of the huge magnetostructural effect in layered Fe-As
+compounds is elucidated using LiFeAs as a prototype. The crucial feature of
+these materials is the strong covalent bonding between Fe and As, which tends
+to suppress the exchange splitting. The bonding-antibonding splitting is very
+sensitive to the distance between Fe and As nuclei. We argue that the fragile
+interplay between bonding and magnetism is universal for this family of
+compounds. The exchange interaction is analyzed in real space, along with its
+correlation with covalency and doping. The range of interaction and itinerancy
+increase as the Fe-As distance is decreased. Superexchange makes a large
+antiferromagnetic contribution to the nearest-neighbor coupling, which develops
+large anisotropy when the local moment is not too small. This anisotropy is
+very sensitive to doping.",0809.2586v3
+2008-09-17,Astrophysical Tests of Lorentz and CPT Violation with Photons,"A general framework for tests of Lorentz invariance with electromagnetic
+waves is presented, allowing for operators of arbitrary mass dimension.
+Signatures of Lorentz violations include vacuum birefringence, vacuum
+dispersion, and anisotropies. Sensitive searches for violations using sources
+such as active galaxies, gamma-ray bursts, and the cosmic microwave background
+are discussed. Direction-dependent dispersion constraints are obtained on
+operators of dimension 6 and 8 using gamma-ray bursts and the blazar Markarian
+501. Stringent constraints on operators of dimension 3 are found using 5-year
+data from the Wilkinson Microwave Anisotropy Probe. No evidence appears for
+isotropic Lorentz violation, while some support at one sigma is found for
+anisotropic violation.",0809.2846v2
+2008-09-22,Tailoring the Magnetic Anisotropy in CoRh Nanoalloys: Experiment and Theory,"The magnetic moments and magnetic anisotropy energy (MAE) of CoRh alloy
+nanoparticles are determined experimentally and theoretically. Non-trivial
+correlations between chemical order, magnetic order and MAE are revealed. A
+remarkable non-monotonous dependence of the MAE as a function of composition
+and chemical order is observed that opens novel possibilities of tuning the
+magnetic properties of nanoalloys. The observations are successfully compared
+and analyzed with our electronic calculations. In this way we clearly
+demonstrate that the induced 4d moments and the 3d-4d interfaces are the key
+parameters controlling the magneto-anisotropic behavior.",0809.3638v1
+2008-09-24,Systematic Distortion in Cosmic Microwave Background Maps,"To minimize instrumentally induced systematic errors, cosmic microwave
+background (CMB) anisotropy experiments measure temperature differences across
+the sky using paires of horn antennas, temperature map is recovered from
+temperature differences obtained in sky survey through a map-making procedure.
+To inspect and calibrate residual systematic errors in recovered temperature
+maps is important as most previous studies of cosmology are based on these
+maps. By analyzing pixel-ring couping and latitude dependence of CMB
+temperatures, we find notable systematic deviation from CMB Gaussianity in
+released Wilkinson Microwave Anisotropy Probe (WMAP) maps. The detected
+deviation is hard to explain by any process in the early universe and can not
+be ignored for a precision cosmology study.",0809.4160v2
+2008-09-30,UHECR observations and lensing in the magnetic field of the Virgo cluster,"We discuss how lensing by magnetic fields in galaxy clusters affects
+ultrahigh energy cosmic ray (UHECR) observations. As specific example, we use
+Virgo together with the cluster magnetic fields obtained earlier in a
+constrained simulation of structure formation including MHD processes. We find
+that, if M87 is the single source of UHECRs from Virgo, the emitted flux is
+strongly anisotropic in the most interesting energy range, (50-100)EeV, and
+differs from the average value by a factor five or more for a significant
+fraction of observers. Since magnetic lensing is energy dependent, the external
+energy spectrum as seen by different observers varies strongly too. These
+anisotropies are averaged out in the case that all active galactic nuclei in
+Virgo emit UHECRs. In both cases, the anisotropies of the emitted UHECR flux
+may introduce an important bias in the interpretation of UHECR data like, e.g.,
+the determination of the source density n_s and the source energy spectrum of
+UHECRs.",0809.5055v2
+2008-10-01,Lorentz-violating contributions of the Carroll-Field-Jackiw model to the CMB anisotropy,"We study the finite temperature properties of the
+Maxwell-Carroll-Field-Jackiw (MCFJ) electrodynamics for a purely spacelike
+background. Starting from the associated finite temperature partition function,
+a modified black body spectral distribution is obtained. We thus show that, if
+the CMB radiation is described by this model, the spectrum presents an
+anisotropic angular energy density distribution. We show, at leading order,
+that the Lorentz-breaking contributions for the Planck's radiation law and for
+the Stefan-Boltzmann's law are nonlinear in frequency and quadratic in
+temperature, respectively. Using our results, we set up bounds for the
+Lorentz-breaking parameter, and show that Lorentz violation in the context of
+the MCFJ model is unable to yield the known CMB anisotropy (of 1 part in
+$10^{5})$.",0810.0306v2
+2008-10-03,"Small anisotropy, weak thermal fluctuations, and high field superconductivity in Co-doped iron pnictide Ba(Fe1-xCox)2As2","We performed high-field magnetotransport and magnetization measurements on a
+single crystal of the 122-phase iron pnictide Ba(Fe1-xCox)2As2. Unlike the HTS
+cuprates and 1111-phase oxypnictides, Ba(Fe1-xCox)2As2 showed practically no
+broadening of the resistive transitions under magnetic fields up to 45 T. The
+mass anisotropy gamma = Hc2ab/Hc2c deduced from the slopes of the upper
+critical field dHc2ab/dT = 4.9T/K and dHc2c/dT = 2.5T/K decreases from ~2 near
+Tc, to ~1.5 at lower temperatures. We observed the irreversibility field close
+to Hc2, and a rather unusual symmetric volume pinning force curve Fp(H)
+suggestive of strong pinning nano-structure.",0810.0699v2
+2008-10-10,Fermi surface and order parameter driven vortex lattice structure transitions in twin-free YBa2Cu3O7,"We report on small-angle neutron scattering studies of the intrinsic vortex
+lattice (VL) structure in detwinned YBa2Cu3O7 at 2 K, and in fields up to 10.8
+T. Because of the suppressed pinning to twin-domain boundaries, a new distorted
+hexagonal VL structure phase is stabilized at intermediate fields. It is
+separated from a low-field hexagonal phase of different orientation and
+distortion by a first-order transition at 2.0(2) T that is probably driven by
+Fermi surface effects. We argue that another first-order transition at 6.7(2)
+T, into a rhombic structure with a distortion of opposite sign, marks a
+crossover from a regime where Fermi surface anisotropy is dominant, to one
+where the VL structure and distortion is controlled by the order-parameter
+anisotropy.",0810.1947v2
+2008-10-14,Effective magnetic penetration depth in superconducting cylinders and spheres with highly anisotropic electrodynamics,"Effective magnetic penetration depth and microwave surface impedance are
+derived for anisotropic layered superconductors in the shape of spheres and
+long cylinders, where the external magnetic field is applied in the plane of
+the highly conducting layers to induce out-of-plane screening currents. The
+results are extended by analytic continuation to highly anisotropic conductors
+and to lossy superconductors at high frequency. The electrodynamics for the
+general case of a superconductor or metal with arbitrary anisotropy are
+presented. The treatment is then specialized to layered materials with
+unixaxial anisotropy, in which the penetration depth for currents flowing
+perpendicular to the layers, lambda_c, is much greater than that for in-plane
+currents, lambda_a. Exact solutions are found in the limit lambda_a goes to
+zero, and are expected to provide an accurate representation of many
+experiments on cuprates and other layered superconductors, particularly on
+grain-aligned powders.",0810.2342v1
+2008-10-14,Energetic selection of ordered states in a model of the Er2Ti2O7 frustrated pyrochlore XY antiferromagnet,"We consider the possibility that the discrete long-range ordered states of
+Er2Ti2O7 are selected energetically at the mean field level as an alternative
+scenario that suggests selection via thermal fluctuations. We show that nearest
+neighbour exchange interactions alone are not sufficient for this purpose, but
+that anisotropies arising from excited single ion crystal field states in
+Er2Ti2O7, together with appropriate anisotropic exchange interactions, can
+produce the required long range order. However, the effect of the single ion
+anisotropies is rather weak so we expect thermal or quantum fluctuations, in
+some guise, to be ultimately important in this material. We reproduce recent
+experimental results for the variation of magnetic Bragg peak intensities as a
+function of magnetic field.",0810.2483v2
+2008-10-16,Dipolar interactions and thermal stability of two-dimensional nanoparticle arrays,"We show results of Monte Carlo simulations of an array of monodispersed
+magnetic monodomain particles, in a square lattice with dipolar interactions
+and perpendicular uniaxial anisotropy. We first show the equilibrium phase
+diagram of the system, which shows three phases, superparamagnetic (SP),
+out-of-plane antiferromagnetic and in-plane antiferromagnetic with a
+reorientation transition between the last two. We then employ a recently
+introduced time quantified Monte Carlo method to study the relaxation of
+autocorrelations of the particle array for different ratios of dipolar to
+anisotropy energies. In the non-interacting case we show that relaxation is
+exponential in time with characteristic times obeying a classic result by
+Brown. When dipolar interactions are switched on, the relaxation is very well
+described by stretched exponential forms in the whole time window and in both
+the SP and ordered phases. Relaxation times still obey a nearly Arrhenius
+behaviour, with a single effective energy barrier that decreases as the dipolar
+interaction increases, a result that must be interpreted within the dynamics
+protocol. No signs of glassy behaviour were found, in agreement with the
+absence of disorder in the model system.",0810.2940v1
+2008-10-24,Spin Dynamics in the Magnetoelectric Effect LiCoPO$_4$ Compound,"Inelastic neutron scattering (INS) experiments were performed to investigate
+the spin dynamics in magnetoelectric effect (ME) LiCoPO$_4$ single crystals.
+Weak dispersion was detected in the magnetic excitation spectra along the three
+principal crystallographic axes measured around the (0 1 0) magnetic
+reflection. Analysis of the data using linear spin-wave theory indicate that
+single-ion anisotropy in LiCoPO$_4$ is as important as the strongest
+nearest-neighbor exchange coupling. Our results suggest that Co$^{2+}$
+single-ion anisotropy plays an important role in the spin dynamics of
+LiCoPO$_4$ and must be taken into account in understanding its physical
+properties. High resolution INS measurements reveal an anomalous low energy
+excitation that we hypothesize may be related to the magnetoelectric effect of
+LiCoPO$_4$.",0810.4471v1
+2008-10-27,Surface morphology and magnetic anisotropy of Fe/MgO(001) films deposited at oblique incidence,"We have studied surface morphology and magnetic properties of Fe/MgO(001)
+films deposited at an angle varying between 0o and 60o with respect to the
+surface normal and with azimuth along the Fe[010] or the Fe[110] direction. Due
+to shadowing, elongated grains appear on the film surface for deposition at
+sufficiently large angle. X-ray reflectivity reveals that, depending on the
+azimuthal direction, films become either rougher or smoother for oblique
+deposition. For deposition along Fe[010] the pronounced uniaxial magnetic
+anisotropy (UMA) results in the occurrence of reversed two-step and of
+three-step hysteresis loops. For deposition along Fe[110] the growth-induced
+UMA is much weaker, causing a small rotation of the easy axes.",0810.4929v1
+2008-10-31,"Anisotropy, Itineracy, and Magnetic Frustration in High-Tc Iron Pnictides","Using first-principle density functional theory calculations combined with
+insight from a tight-binding representation, dynamical mean field theory, and
+linear response theory, we have extensively investigated the electronic
+structures and magnetic interactions of nine ferropnictides representing three
+different structural classes. The calculated magnetic interactions are found to
+be short-range, and the nearest ($J_{1a}$) and next-nearest ($J_{2}$) exchange
+constants follow the universal trend of J_{1a}/2J_{2}\sim 1, despite their
+itinerant origin and extreme sensitivity to the z-position of As. These results
+bear on the discussion of itineracy versus magnetic frustration as the key
+factor in stabilizing the superconducting ground state. The calculated spin
+wave dispersions show strong magnetic anisotropy in the Fe plane, in contrast
+to cuprates.",0811.0034v3
+2008-11-03,The full contribution of a stochastic background of magnetic fields to CMB anisotropies,"We study the contribution of a stochastic background (SB) of primordial
+magnetic fields (PMF) on the anisotropies in temperature and polarization of
+the cosmic microwave background radiation (CMB). A SB of PMF modelled as a
+fully inhomogeneous component induces non-gaussian scalar, vector and tensor
+metric linear perturbations. We give the exact expressions for the Fourier
+spectra of the relevant energy-momentum components of such SB, given a
+power-law dependence parametrized by a spectral index $n_B$ for the magnetic
+field power spectrum cut at a damping scale $k_D$. For all the values of $n_B$
+considered here, the contribution to the CMB temperature pattern by such a SB
+is dominated by the scalar contribution and then by the vector one at higher
+multipoles. We also give an analytic estimate of the scalar contribution to the
+CMB temperature pattern.",0811.0230v2
+2008-11-06,The microscopic theory of the upper critical field Hc2 in two-band systems in the magnetic field directed parallel and perpendicular to the plane (ab). Application to MgB2,"The microscopic superconductivity theory in MgB2 systems in the magnetic
+fields directed parallel and perpendicular to the plane (ab) is built. The two
+energy bands of different dimensions overlapping on the Fermi surface
+(two-dimensional sigma- band and three-dimensional pi-band) are taken into
+account. The theory is built taking into account the weak dispersion of the
+electron energy of sigma -band in z direction. The systems of equations for the
+superconductive transition temperature Tc and the upper critical field Hc2(ab)
+are obtained. The analytic solutions of the equations for Hc2^0(ab) are found
+in the two temperature areas: nearby the zero temperature T<<Tc^0 and in the
+vicinity of the superconductive transition temperature Tc^0-T<<Tc^0. The
+temperature dependencies of the upper critical fields Hc2(ab) and Hc2(c) on the
+temperature are built, and the anisotropy coefficient gammaH=Hc2^0(ab)/Hc2^0(c)
+is determined. It is shown that the value of Hc2(ab) exceeds greatly the value
+of Hc2(c) due to the system anisotropy (to small values of the average velocity
+of electrons in the crystallographic axis direction).",0811.0897v1
+2008-11-14,Superfluid $^3$He in globally isotropic random media,"Recent theoretical and experimental studies of superfluid $^3$He in aerogels
+with a global anisotropy, e.g., due to an external stress, have definitely
+shown that the A-like phase with an equal spin pairing (ESP) in such aerogel
+samples is in the ABM (or, axial) pairing state. In this paper, the A-like
+phase of superfluid $^3$He in globally {\it isotropic} aerogel is studied in
+details by assuming a weakly disordered system in which singular topological
+defects are absent. Through calculation of the free energy, a disordered ABM
+state is found to be the best candidate of the pairing state of the globally
+isotropic A-like phase. Further, it is found through a one-loop renormalization
+group calculation that the coreless continuous vortices (or, vortex-skyrmions)
+are irrelevant to the long-distance behavior of the disorder-induced textures,
+and that the superfluidity is maintained in spite of lack of the conventional
+off-diagonal long range order. Therefore, the globally isotropic A-like phase
+at weak disorder is, like in the case with a global stretched anisotropy, a
+superfluid glass with the ABM pairing.",0811.2292v2
+2008-11-16,Anisotropy in spatial order-disorder transformations and the vortex lattice symmetry transition in $YNi_2B_2C$ and $LuNi_2B_2C$,"Explorations of the order-disorder transformation in vortex matter in single
+crystals of tetragonal structured (c/a $\sim$3) borocarbide superconductors,
+$YNi_2B_2C$ and $LuNi_2B_2C$, reveal that vortex arrays experience different
+effective pinning in different crystallographic directions. We surmise that
+correlation exists between the large anisotropy in effective pinning/disorder
+and the differences in the (local) symmetry transition from rhombohedral to
+(quasi) square vortex lattice(VL). For field along high symmetry directions,
+like, c-axis and ab-basal plane, the VL symmetry is close to square and the
+ordered state spans a large field interval. When the field is turned away from
+the c-axis towards ab-plane, at intermediate angles, the region of ordered
+state shrinks, in response to enhancement in effective pinning. At such
+intermediate angles the symmetry of the VL would be far from ideal triangular
+or square.",0811.2602v1
+2008-11-17,Dynamics of Gas-Fluidized Granular Rods,"We study a quasi-two-dimensional monolayer of granular rods fluidized by a
+spatially and temporally homogeneous upflow of air. By tracking the position
+and orientation of the particles, we characterize the dynamics of the system
+with sufficient resolution to observe ballistic motion at the shortest time
+scales. Particle anisotropy gives rise to dynamical anisotropy and
+superdiffusive dynamics parallel to the rod's long axis, causing the parallel
+and perpendicular mean squared displacements to become diffusive on different
+timescales. The distributions of free times and free paths between collisions
+deviate from exponential behavior, underscoring the non-thermal character of
+the particle motion. The dynamics show evidence of rotational-translational
+coupling similar to that of an anisotropic Brownian particle. We model
+rotational-translation coupling in the single-particle dynamics with a modified
+Langevin model using non-thermal noise sources. This suggests a
+phenomenological approach to thinking about collections of self-propelling
+particles in terms of enhanced memory effects.",0811.2751v1
+2008-11-19,Possible Verification of Tilted Anisotropic Dirac Cone in α-(BEDT-TTF)_2 I_3 Using Interlayer Magnetoresistance,"It is proposed that the presence of a tilted and anisotropic Dirac cone can
+be verified using the interlayer magnetoresistance in the layered Dirac fermion
+system, which is realized in quasi-two-dimensional organic compound
+\alpha-(BEDT-TTF)_2 I_3. Theoretical formula is derived using the analytic
+Landau level wave functions and assuming local tunneling of electrons. It is
+shown that the resistivity takes the maximum in the direction of the tilt if
+anisotropy of the Fermi velocity of the Dirac cone is small. The procedure is
+described to determine the parameters of the tilt and anisotropy.",0811.3041v3
+2008-11-28,On the non-Gaussianity from Recombination,"The non-linear effects operating at the recombination epoch generate a
+non-Gaussian signal in the CMB anisotropies. Such a contribution is relevant
+because it represents a major part of the second-order radiation transfer
+function which must be determined in order to have a complete control of both
+the primordial and non-primordial part of non-Gaussianity in the CMB
+anisotropies. We provide an estimate of the level of non-Gaussianity in the CMB
+arising from the recombination epoch which shows up mainly in the equilateral
+configuration. We find that it causes a contamination to the possible
+measurement of the equilateral primordial bispectrum shifting the minimum
+detectable value of the non-Gaussian parameter f^equil_NL by Delta f^equil_NL=
+O(10) for an experiment like Planck.",0811.4584v3
+2008-11-28,Fast rotating Bose-Einstein condensates in an asymmetric trap,"We investigate the effect of the anisotropy of a harmonic trap on the
+behaviour of a fast rotating Bose-Einstein condensate. This is done in the
+framework of the 2D Gross-Pitaevskii equation and requires a symplectic
+reduction of the quadratic form defining the energy. This reduction allows us
+to simplify the energy on a Bargmann space and study the asymptotics of large
+rotational velocity. We characterize two regimes of velocity and anisotropy; in
+the first one where the behaviour is similar to the isotropic case, we
+construct an upper bound: a hexagonal Abrikosov lattice of vortices, with an
+inverted parabola profile. The second regime deals with very large velocities,
+a case in which we prove that the ground state does not display vortices in the
+bulk, with a 1D limiting problem. In that case, we show that the coarse grained
+atomic density behaves like an inverted parabola with large radius in the
+deconfined direction but keeps a fixed profile given by a Gaussian in the other
+direction. The features of this second regime appear as new phenomena.",0811.4714v1
+2008-12-02,U(1)-Symmetry breaking and violation of axial symmetry in TlCuCl3 and other insulating spin systems,"We describe the Bose-Einstein condensate of magnetic bosonic quasiparticles
+in insulating spin systems using a phenomenological standard functional method
+for T = 0. We show that results that are already known from advanced
+computational techniques immediately follow. The inclusion of a perturbative
+anisotropy term that violates the axial symmetry allows us to remarkably well
+explain a number of experimental features of the dimerized spin-1/2 system
+TlCuCl3. Based on an energetic argument we predict a general intrinsic
+instability of an axially symmetric magnetic condensate towards a violation of
+this symmetry, which leads to the spontaneous formation of an anisotropy gap in
+the energy spectrum above the critical field. We, therefore, expect that a true
+Goldstone mode in insulating spin systems, i.e., a strictly linear
+energy-dispersion relation down to arbitrarily small excitations energies,
+cannot be observed in any real material.",0812.0535v3
+2008-12-04,Exchange bias and its phase reversal in the zero magnetization admixed rare earth intermetallics,"Exchange bias effect is an important attribute in several device
+applications. Traditionally, it is discussed as a form of exchange anisotropy
+at the interface between the ferromagnetic/antiferromagnetic layers of two
+distinct systems. We report here on the magnetically ordered alloys possessing
+the feature of unidirectional anisotropy, which reverses its sign across a
+characteristic temperature. These are admixed rare earth intermetallics,
+comprising two dissimilar rare earth (RE) ions, belonging to the two different
+halves of the 4f-series and imbibing the notion of ferromagnetic coupling
+between the spins of all 4f-rare earth ions and that of the conduction
+electrons. Magnetic moments of dissimilar RE ions in such admixed alloys,
+however, get antiferromagnetically coupled and they display magnetic
+compensation feature such that the field induced reversal in the orientation of
+the magnetic moments of dissimilar rare earth ions happens across the
+compensation temperature (Tcomp). Above a threshold field, the conduction
+electron polarization also reverses its sign across Tcomp, this is argued to
+correlate with the observed phase reversal in the exchange bias field.",0812.0929v1
+2008-12-08,Measuring the isotropization time of quark-gluon plasma from direct photons at energies available at the BNL Relativistic Heavy Ion Collider (RHIC),"We calculate transverse momentum distribution of direct photons from various
+sources by taking into account the initial state momentum anisotropy of {\em
+Quark-Gluon-Plasma} (QGP) and late stage transverse flow effects. The total
+photon yield, calculated for various combinations of initial conditions,
+transition temperatures, is then compared with the recent measurement of photon
+transverse momentum distribution by the PHENIX collaboration. It is shown that
+the presence of such an anisotropy can describe the PHENIX photon data better
+than the isotropic case. We show that the isotropization time thus extracted
+remains of the order of 1 fm/c and is almost insensitive to the initial
+conditions used.",0812.1478v3
+2008-12-08,High domain wall velocities induced by current in ultrathin Pt/Co/AlOx wires with perpendicular magnetic anisotropy,"Current-induced domain wall (DW) displacements in an array of ultrathin
+Pt/Co/AlOx wires with perpendicular magnetic anisotropy have been directly
+observed by wide field Kerr microscopy. DWs in all wires in the array were
+driven simultaneously and their displacement on the micrometer-scale was
+controlled by the current pulse amplitude and duration. At the lower current
+densities where DW displacements were observed (j less than or equal to 1.5 x
+10^12 A/m^2), the DW motion obeys a creep law. At higher current density (j =
+1.8 x 10^12 A/m^2), zero-field average DW velocities up to 130 +/- 10 m/s were
+recorded.",0812.1515v2
+2008-12-18,Interplay of anisotropy and frustration: triple transitions in a triangular-lattice antiferromagnet,"The classical Heisenberg antiferromagnet on a triangular lattice with the
+single-ion anisotropy of the easy-axis type is theoretically investigated. The
+mean-field phase diagram in an external magnetic field is constructed. Three
+finite-temperature Berezinskii-Kosterlitz-Thouless transitions are found by the
+Monte Carlo simulations in zero field. The two upper transitions are related to
+the breaking of the discrete ${\mathbb Z}_{6}$ symmetry group, while the lowest
+transition is associated with a quasi-long-range ordering of transverse
+components. The intermediate collinear phase between first and second
+transitions is the sliding phase predicted by J. V. Jos\'e {\it et al}. [Phys.
+Rev. B {\bf 16}, 1217 (1977)].",0812.3574v2
+2008-12-22,Observation of superspin glass state in magnetically textured ferrofluid (gamma-Fe2O3),"Magnetic properties in a magnetically textured ferrofluid made out of
+interacting maghemite (gamma-Fe2O3) nanoparticles suspended in glycerin have
+been investigated. Despite the loss of uniform distribution of anisotropy axes,
+a superspin glass state exists at low temperature in a concentrated, textured
+ferrofluid as in the case of its non-textured counterpart. The onset of
+superspin glass state was verified from the sample's AC susceptibility. The
+influence of the anisotropy axis orientation on the aging behavior in the
+glassy states is also discussed.",0812.4282v2
+2008-12-25,Band-power reconstruction of the primordial fluctuation spectrum by the maximum likelihood reconstruction method,"The primordial curvature fluctuation spectrum is reconstructed by the maximum
+likelihood reconstruction method using the five-year Wilkinson Microwave
+Anisotropy Probe data of the cosmic microwave background temperature
+anisotropy. We apply the covariance matrix analysis and decompose the
+reconstructed spectrum into statistically independent band-powers. The
+prominent peak off a simple power-law spectrum found in our previous analysis
+turn out to be a $3.3\sigma$ deviation. From the statistics of primordial
+spectra reconstructed from mock observations, the probability that a primordial
+spectrum including such excess is realized in a power-law model is estimated to
+be about 2%.",0812.4585v2
+2009-01-08,Angular distributions of leptons from J/psi's produced in 920 GeV fixed-target proton-nucleus collisions,"A study of the angular distributions of leptons from decays of J/psi's
+produced in p-C and p-W collisions at sqrt{s}=41.6 GeV has been performed in
+the Feynman-x region -0.34 < x_F < 0.14 and for transverse momentum up to 5.4
+GeV/c. The data were collected by the HERA-B experiment at the HERA proton ring
+of the DESY laboratory. The results, based on a clean selection of 2.3 x 10^5
+J/psi's reconstructed in both the e^+ e^- and mu^+ mu^- decay channels,
+indicate that J/psi's are produced with longitudinal polarization. The
+magnitude of the effect is maximal at low p_T. For p_T >1 GeV/c a significant
+dependence on the reference frame is found: the polar anisotropy is more
+pronounced in the Collins-Soper frame and almost vanishes in the helicity
+frame, where, instead, a significant azimuthal anisotropy arises.",0901.1015v1
+2009-01-10,Adiabatic dynamics in a spin-1 chain with uniaxial single-spin anisotropy,"We study the adiabatic quantum dynamics of an anisotropic spin-1 XY chain
+across a second order quantum phase transition. The system is driven out of
+equilibrium by performing a quench on the uniaxial single-spin anisotropy, that
+is supposed to vary linearly in time. We show that, for sufficiently large
+system sizes, the excess energy after the quench admits a non trivial scaling
+behavior that is not predictable by standard Kibble-Zurek arguments for
+isolated critical points or extended critical regions. This emerges from a
+competing effect of many accessible low-lying excited states, inside the whole
+continuous line of critical points.",0901.1384v3
+2009-01-14,Quarkonium states in an anisotropic QCD plasma,"We consider quarkonium in a hot QCD plasma which, due to expansion and
+non-zero viscosity, exhibits a local anisotropy in momentum space. At short
+distances the heavy-quark potential is known at tree level from the
+hard-thermal loop resummed gluon propagator in anisotropic perturbative QCD.
+The potential at long distances is modeled as a QCD string which is screened at
+the same scale as the Coulomb field. At asymptotic separation the potential
+energy is non-zero and inversely proportional to the temperature. We obtain
+numerical solutions of the three-dimensional Schroedinger equation for this
+potential. We find that quarkonium binding is stronger at non-vanishing
+viscosity and expansion rate, and that the anisotropy leads to polarization of
+the P-wave states.",0901.1998v2
+2009-01-15,Rogues' gallery: the full freedom of the Bianchi CMB anomalies,"Combining a recent derivation of the CMB evolution equations for homogeneous
+but anisotropic (Bianchi) cosmologies with an account of the full linearized
+dynamical freedoms available in such models, I calculate and discuss the
+various temperature and polarisation anisotropy patterns which may be formed.
+Certain anisotropies can be hidden in superhorizon modes at early times, thus
+avoiding any constraints from nucleosynthesis while nevertheless producing
+non-trivial redshift-zero temperature patterns in flat and open universes. The
+results are likely to be more of pedagogical than observational interest, but
+future work will assess whether such patterns can be matched to anomalies in
+WMAP results.",0901.2122v2
+2009-01-15,Two-gap superconductivity in Ba_1-xK_xFe_2As_2: A complementary study of the magnetic penetration depth by \muSR and ARPES,"We investigate the magnetic penetration depth \lambda in superconducting
+Ba_1-xK_xFe_2As_2 (T_c\simeq32K) with muon-spin rotation (\muSR) and
+angle-resolved photoemission (ARPES). Using \muSR, we find the
+penetration-depth anisotropy \gamma_\lambda=\lambda_c/\lambda_{ab} and the
+second-critical-field anisotropy \gamma_{H_c2} to show an opposite T-evolution
+below T_c. This dichotomy resembles the situation in the two-gap superconductor
+MgB_2. A two-gap scenario is also suggested by an inflection point in the
+in-plane penetration depth \lambda_ab around 7K. The complementarity of \muSR
+and ARPES allows us to pinpoint the values of the two gaps and to arrive to a
+remarkable agreement between the two techniques concerning the full T-evolution
+of \lambda_ab. This provides further support for the described scenario and
+establishes ARPES as a tool to assess macroscopic properties of the
+superconducting condensate.",0901.2329v2
+2009-01-16,Prospects for sympathetic cooling of polar molecules: NH with alkali-metal and alkaline-earth atoms - a new hope,"We explore the potential energy surfaces for NH molecules interacting with
+alkali-metal and alkaline-earth atoms using highly correlated ab-initio
+electronic structure calculations. The surfaces for interaction with
+alkali-metal atoms have deep wells dominated by covalent forces. The resulting
+strong anisotropies will produce strongly inelastic collisions. The surfaces
+for interaction with alkaline-earth atoms have shallower wells that are
+dominated by induction and dispersion forces. For Be and Mg the anisotropy is
+small compared to the rotational constant of NH, so that collisions will be
+relatively weakly inelastic. Be and Mg are thus promising coolants for
+sympathetic cooling of NH to the ultracold regime.",0901.2493v2
+2009-01-19,Anisotropy probe of galactic and extra-galactic Dark Matter annihilations,"We study the flux and the angular power spectrum of gamma-rays produced by
+Dark Matter (DM) annihilations in the Milky Way (MW) and in extra-galactic
+halos. The annihilation signal receives contributions from: a) the smooth MW
+halo, b) resolved and unresolved substructures in the MW, c) external DM halos
+at all redshifts, including d) their substructures. Adopting a self-consistent
+description of local and extra-galactic substructures, we show that the
+annihilation flux from substructures in the MW dominates over all the other
+components for angles larger than O(1) degrees from the Galactic Center, unless
+an extreme prescription is adopted for the substructures concentration. We also
+compute the angular power spectrum of gamma-ray anisotropies and find that, for
+an optimistic choice of the particle physics parameters, an interesting
+signature of DM annihilations could soon be discovered by the Fermi LAT
+satellite at low multipoles, l<100, where the dominant contribution comes from
+MW substructures with mass M>10^4 solar masses. For the substructures models we
+have adopted, we find that the contribution of extra-galactic annihilations is
+instead negligible at all scales.",0901.2921v1
+2009-01-31,Hall Coefficient of Equilibrium Supercurrents Flowing inside Superconductors,"We study augmented quasiclassical equations of superconductivity with the
+Lorentz force, which is missing from the standard Ginzburg-Landau and
+Eilenberger equations. It is shown that the magnetic Lorentz force on
+equilibrium supercurrents induces finite charge distribution and the resulting
+electric field to balance the Lorentz force. An analytic expression is obtained
+for the corresponding Hall coefficient of clean type-II superconductors with
+simultaneously incorporating the Fermi-surface and gap anisotropies. It has the
+same sign and magnitude at zero temperature as the normal state for an
+arbitrary pairing, having no temperature dependence specifically for the s-wave
+pairing. The gap anisotropy may bring a considerable temperature dependence in
+the Hall coefficient and can lead to its sign change as a function of
+temperature, as exemplified for a model d-wave pairing with a two-dimensional
+Fermi surface. The sign change may be observed in some high-$T_{c}$
+superconductors.",0902.0042v1
+2009-02-03,Polarized wavelets and curvelets on the sphere,"The statistics of the temperature anisotropies in the primordial cosmic
+microwave background radiation field provide a wealth of information for
+cosmology and for estimating cosmological parameters. An even more acute
+inference should stem from the study of maps of the polarization state of the
+CMB radiation. Measuring the extremely weak CMB polarization signal requires
+very sensitive instruments. The full-sky maps of both temperature and
+polarization anisotropies of the CMB to be delivered by the upcoming Planck
+Surveyor satellite experiment are hence being awaited with excitement.
+Multiscale methods, such as isotropic wavelets, steerable wavelets, or
+curvelets, have been proposed in the past to analyze the CMB temperature map.
+In this paper, we contribute to enlarging the set of available transforms for
+polarized data on the sphere. We describe a set of new multiscale
+decompositions for polarized data on the sphere, including decimated and
+undecimated Q-U or E-B wavelet transforms and Q-U or E-B curvelets. The
+proposed transforms are invertible and so allow for applications in data
+restoration and denoising.",0902.0574v1
+2009-02-09,Evolution of Cosmological Perturbations in the Presence of Primordial Magnetic Fields,"Possible existence of the primordial magnetic fields has affected the
+structure formation of the universe. In this paper it is shown that the initial
+conditions for density perturbations with magnetic fields derived in previous
+works are inconsistent with Einstein equations. We find that this inconsistency
+arises due to the unwanted cancellation of contributions from the magnetic
+fields and primordial radiations. A complete set of equations and consistent
+initial conditions in the long wavelength limit are given with an explicit
+derivation in the covariant approach with CDM frame, by newly taking into
+account a non-relativistic matter contribution in the radiation dominated era.
+By solving these equations numerically, we derive the angular spectrum of
+cosmic microwave background anisotropies and the matter power spectrum with
+magnetic fields. We find that the amplitude of the angular power spectrum of
+CMB anisotropies can alter at most a order of magnitude at $l \lesssim 4000$
+compared with the previous results in the literature.",0902.1367v2
+2009-02-17,Inflationary Universe with Anisotropic Hair,"We study an inflationary scenario with a vector field coupled with an
+inflaton field and show that the inflationary universe is endowed with
+anisotropy for a wide range of coupling functions. This anisotropic inflation
+is a tracking solution where the energy density of the vector field follows
+that of the inflaton field irrespective of initial conditions. We find a
+universal relation between the anisotropy and a slow-roll parameter of
+inflation. Our finding has observational implications and gives a counter
+example to the cosmic no-hair conjecture.",0902.2833v2
+2009-02-24,Finite-Size Scaling Critical Behavior of Randomly Pinned Spin-Density Waves,"We have performed Monte Carlo studies of the 3D $XY$ model with random
+uniaxial anisotropy, which is a model for randomly pinned spin-density waves.
+We study $L \times L \times L$ simple cubic lattices, using $L$ values in the
+range 16 to 64, and with random anisotropy strengths of $D / 2 J$ = 1, 2, 3, 6
+and $\infty$. There is a well-defined finite temperature critical point, $T_c$,
+for each these values of $D / 2 J$. We present results for the angle-averaged
+magnetic structure factor, $S (k)$ at $T_c$ for $L = 64$. We also use
+finite-size scaling analysis to study scaling functions for the critical
+behavior of the specific heat, the magnetization and the longitudinal magnetic
+susceptibility. Good data collapse of the scaling functions over a wide range
+of $T$ is seen for $D / 2 J$ = 6 and $\infty$. For our finite values of $D / 2
+J$ the scaled magnetization function increases with $L$ below $T_c$, and
+appears to approach an $L$-independent limit for large $L$. This suggests that
+the system is ferromagnetic below $T_c$.",0902.4049v2
+2009-02-27,Monte Carlo Determination of the Low-Energy Constants of a Spin 1/2 Heisenberg Model with Spatial Anisotropy,"Motivated by the possible mechanism for the pinning of the electronic liquid
+crystal direction in YBCO as proposed in \cite{Pardini08}, we use the first
+principles Monte Carlo method to study the spin 1/2 Heisenberg model with
+antiferromagnetic couplings $J_{1}$ and $J_{2}$ on the square lattice. The
+corresponding low-energy constants, namely the spin stiffness $\rho_s$, the
+staggered magnetization density ${\cal M}_s$, the spin wave velocity $c$, as
+well as the ground state energy density $e_0$ are determined by fitting the
+Monte Carlo data to the predictions of magnon chiral perturbation theory. In
+particular, the spin stiffnesses $\rho_{s1}$ and $\rho_{s2}$ are investigated
+as a function of the ratio $J_{2}/J_{1}$ of the couplings. Although we find a
+good agreement between our results with those obtained by the series expansion
+method in the weakly anisotropic regime, for strong anisotropy we observe
+discrepancies.",0902.4861v3
+2009-02-27,Superconductivity at 23 K and Low Anisotropy in Rb-Substituted BaFe_2As_2 Single Crystals,"Single crystals of Ba_{1-x}Rb_{x}Fe_2As_2 with x=0.05-0.1 have been grown
+from Sn flux and are bulk superconductors with T_c up to 23 K. The crystal
+structure was determined by X-ray diffraction analysis, and Sn is found to be
+incorporated for 9% Ba, shifted by 1.1 Angstroem away from the Ba site towards
+the (Fe_2As_2)-layers. The upper critical field deduced from resistance
+measurements is anisotropic with slopes of 7.1(3) T/K (H || ab-plane) and
+4.2(2) T/K (H || c-axis), sufficiently far below T_c. The extracted upper
+critical field anisotropy of 3 close to T_c, is in good agreement with the
+estimate from magnetic torque measurements. This indicates that the electronic
+properties in the doped BaFe_2As_2 compound are significantly more isotropic
+than those in the LnFeAsO family. The in-plane critical current density at 5 K
+exceeds 10^6 A/cm^2, making Ba_{1-x}Rb_xFe_2As_2 a promising candidate for
+technical applications.",0903.0004v2
+2009-03-08,Spherical magnetic nanoparticles: magnetic structure and interparticle interaction,"The interaction between spherical magnetic nanoparticles is investigated from
+micromagnetic simulations and ananlysed in terms of the leading dipolar
+interaction energy between magnetic dipoles. We focus mainly on the case where
+the particles present a vortex structure. In a first step the local magnetic
+structure in the isolated particle is revisited. For particles bearing a
+uniaxial magnetocrystaline anisotropy, it is shown that the vortex core
+orientation relative to the easy axis depends on both the particle size and the
+anisotropy constant. When the particles magnetization present a vortex
+structure, it is shown that the polarization of the particles by the dipolar
+field of the other one must be taken into account in the interaction. An
+analytic form is deduced for the interaction which involves the vortex core
+magnetization and the magnetic susceptibility which are obtained from the
+magnetic properties of the isolated particle.",0903.1423v2
+2009-03-09,Mangetic phase transition for three-dimensional Heisenberg weak random anisotropy model: Monte Carlo study,"Magnetic phase transition (MPT) to magnetic quasi-long-range order (QLRO)
+phase in a three-dimensional Heisenberg weak (D/J=4) random anisotropy (RA)
+model is investigated by Monte Carlo simulation. The isotropic and cubic
+distributions of RA axes are considered for simple-cubic-lattice systems.
+Finite-size scaling analysis shows that the critical couplings for the former
+and latter are K_c= 0.70435(2) and K_c=0.70998(4), respectively. While the
+critical exponent 1/\nu =1.40824(0) is the same for both cases. A second-order
+MPT to the QLRO phase is therefore evidenced to be possible in favor with the
+existence of the QLRO predicted by recent functional renormalization group
+theories.",0903.1581v1
+2009-03-09,"Thermal and Transport Behavior of Single Crystalline R2CoGa8 (R = Gd, Tb, Dy, Ho, Er, Tm, Lu and Y) Compounds","The anisotropy in electrical transport and thermal behavior of single
+crystalline R$_{2}$CoGa$_{8}$ series of compounds is presented. These compounds
+crystallize in a tetragonal structure with space gropup P4/mmm. The nonmagnetic
+counterparts of the series namely Y$_{2}$CoGa$_{8}$ and Lu$_{2}$CoGa$_{8}$show
+a behavior consistent with the low density of states at the fermi level. In
+Y$_{2}$CoGa$_{8}$, a possibility of charge density wave transition is observed
+at $\approx$ 30 K. Gd$_{2}$CoGa$_{8}$ and Er$_{2}$CoGa$_{8}$ show a presence of
+short range correlation above the magnetic ordering temperature of the
+compound. In case of Gd$_{2}$CoGa$_{8}$, the magnetoresistance exhibits a
+significant anisotropy for current parallel to {[}100{]} and {[}001{]}
+directions. Compounds with other magnetic rare earths (R = Tb, Dy, Ho and Tm)
+show the normal expected magnetic behavior whereas Dy$_{2}$CoGa$_{8}$ exhibits
+the possibility of charge density wave (CDW) transition at approximately same
+temperature as that of Y$_{2}$CoGa$_{8}$. The thermal property of these
+compounds is analysed on the basis of crystalline electric field (CEF)
+calculations.",0903.1607v1
+2009-03-11,"Cosmological Alfvén waves in the recent CMB data, and the observational bound on the primordial vector perturbation","In the presence of the primordial magnetic field, initial vector (vorticity)
+perturbations produce cosmological Alfven waves and leave imprints on cosmic
+microwave background (CMB) temperature and polarization anisotropy. We have
+investigated imprints of cosmological Alfven waves in CMB anisotropy. For data
+constraints, we have used the power spectrum of the recent CMB observations,
+and correlations estimated from WMAP Internal Linear Combination (ILC) maps.
+Our analysis shows 3 sigma evidence of cosmological Alfven waves. Using the 3
+sigma limit from our analysis and the Alfven velocity limit from the total
+energy density constraint, we impose a lower bound on the amplitude of
+primordial vector perturbation: 4*10^-12 at k_0=0.002/Mpc.",0903.1930v6
+2009-03-11,Scaling of the fidelity susceptibility in a disordered quantum spin chain,"The phase diagram of a quantum XY spin chain with Gaussian-distributed random
+anisotropies and transverse fields is investigated, with focus on the fidelity
+susceptibility, a recently introduced quantum information theoretical measure.
+Monitoring the finite-size scaling of the probability distribution of this
+quantity as well as its average and typical values, we detect a
+disorder-induced disappearance of criticality and the emergence of Griffiths
+phases in this model. It is found that the fidelity susceptibility is not
+self-averaging near the disorder-free quantum critical lines. At the Ising
+critical point the fidelity susceptibility scales as a disorder-strength
+independent stretched exponential of the system size, in contrast with the
+quadratic scaling at the corresponding point in the disorder-free XY chain.
+Along the line where the average anisotropy vanishes the fidelity
+susceptibility appears to scale extensively, whereas in the disorder-free case
+this point is quantum critical with quadratic finite-size scaling.",0903.2069v2
+2009-03-14,Three-Qubit Ground State and Thermal Entanglement of $XXZ$ Model With Dzyaloshinskii-Moriya Interaction,"We have studied the symmetric and non-symmetric pairwise ground state and
+thermal entanglement in three-qubit anisotropic Heisenberg (XXZ) and Ising in a
+magnetic field models and in the presence of Dzyaloshinskii-Moriya (DM)
+interaction. We have found that increasing of the DM interaction and magnetic
+field can enhance and reduce the entanglement of system. We have shown that the
+non-symmetric pairwise has higher value concurrence and critical temperature
+(above which the entanglement vanishes) than the symmetric pairwise. For
+negative anisotropy the non-symmetric entanglement is a monotonic function of
+DM interaction while for positive anisotropy it has a maximum versus DM
+parameter and vanishes for larger values of DM interaction. The conditions for
+the existence of thermal entanglement are discussed in details. The most
+remarkable result happens at zero temperature where 3-qubit ground state
+entanglement of the system (in spite of 2-qubit counterpart) shows the
+fingerprint of quantum phase transition for an infinite size system.",0903.2556v1
+2009-03-19,Plane-mirroring anomaly in the cosmic microwave background maps,"The plane-mirror symmetry previously noticed in the Cosmic Microwave
+Background (CMB) temperature anisotropy maps of Wilkinson Microwave Anisotropy
+Probe is shown to possess certain anomalous properties. The degree of the
+randomness determined by the Kolmogorov stochasticity parameter in the both
+symmetry regions appears to have identical values which, however, essentially
+differ from the corresponding values for other sky regions. If the mirroring
+were of cosmological origin, this would imply either additional randomizing
+properties in those directions of the Universe or their different line-of-sight
+depth. This analysis also provides a way to test the hypothesis of a link
+between the nature of dark energy and inhomogeneities.",0903.3273v1
+2009-03-21,Anisotropic universal conductance fluctuations in disordered quantum wires with Rashba and Dresselhaus spin-orbit interaction and applied in-plane magnetic field,"We investigate the transport properties of narrow quantum wires realized in
+disordered two-dimensional electron gases in the presence of k-linear Rashba
+and Dresselhaus spin-orbit interaction (SOI), and an applied in-plane magnetic
+field. Building on previous work [Scheid, et al., PRL 101, 266401 (2008)], we
+find that in addition to the conductance, the universal conductance
+fluctuations also feature anisotropy with respect to the magnetic field
+direction. This anisotropy can be explained solely from the symmetries
+exhibited by the Hamiltonian as well as the relative strengths of the Rashba
+and Dresselhaus spin orbit interaction and thus can be utilized to detect this
+ratio from purely electrical measurements.",0903.3656v1
+2009-04-28,Scaling behavior of the crossover to short-stack regimes of Josephson vortex lattices in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ stacks,"We report the systematic investigations of the oscillation of the Josephson
+vortex (JV) flow resistance in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$
+micro-fabricated junctions with various geometries and superconducting
+anisotropy parameters. As the applied magnetic field parallel to the $ab$-plane
+is increased, oscillation with a period corresponding to a $\phi_0/2$ par
+atomic Josephson junction changes to oscillation with a doubled period. This
+crossover is scaled by both the junction length and the anisotropy parameter,
+indicating that the bulk inductive coupling that favors the triangular JV
+lattice is replaced with the surface deformation energy as the dominant
+interaction for a JV lattice. These results suggest that the in-phase square JV
+lattice is pronounced at a higher magnetic field in a smaller and more
+anisotropic sample.",0904.4389v1
+2009-04-28,Ising versus XY anisotropy in frustrated R$_{2}$Ti$_{2}$O$_7$ compounds as seen by polarized neutrons,"We studied the field induced magnetic order in R$_{2}$Ti$_{2}$O$_7$
+pyrochlore compounds with either uniaxial (R=Ho, Tb) or planar (R=Er, Yb)
+anisotropy, by polarized neutron diffraction. The determination of the local
+susceptibility tensor \{$\chi_\parallel,\chi_\perp$\} provides a universal
+description of the field induced structures in the paramagnetic phase (2-270
+K), whatever the field value (1-7 T) and direction. Comparison of the thermal
+variations of $\chi_\parallel$ and $\chi_\perp$ with calculations using the
+rare earth crystal field shows that exchange and dipolar interactions must be
+taken into account. We determine the molecular field tensor in each case and
+show that it can be strongly anisotropic.",0904.4440v1
+2009-04-30,Stabilization of Skyrmion textures by uniaxial distortions in noncentrosymmetric cubic helimagnets,"In cubic noncentrosymmetric ferromagnets uniaxial distortions suppress the
+helical states and stabilize Skyrmion lattices in a broad range of
+thermodynamical parameters. Using a phenomenological theory for modulated and
+localized states in chiral magnets, the equilibrium parameters of the Skyrmion
+and helical states are derived as functions of the applied magnetic field and
+induced uniaxial anisotropy. These results show that due to a combined effect
+of induced uniaxial anisotropy and an applied magnetic field Skyrmion lattices
+can be formed as thermodynamically stable states in large intervals of magnetic
+field and temperatures in cubic helimagnets, e.g., in intermetallic compounds
+MnSi, FeGe, (Fe,Co)Si. We argue that this mechanism is responsible for the
+formation of Skyrmion states recently observed in thin layers of
+Fe_{0.5}Co_{0.5}Si [X.Z.Yu et al., Nature \textbf{465}(2010) 901].",0904.4842v2
+2009-05-01,Maxwell and Kerr effects in solutions of macromolecules with dendrons in side groups,"Linear polymers with dendrons of first and second generations based on
+L-aspargic acid are studied by the methods of flow birefringence and electric
+birefringence. Optical, dipole, dynamic, and conformational properties of the
+macromolecules, as well as contributions to their optical anisotropy due to
+macroform and microform effects, are investigated. The polymers are found to
+possess permanent electric dipole moments and undergo reorientation in external
+electric and hydrodynamic fields according to large-scale rotation mechanism. A
+significant growth in equilibrium rigidity, optical anisotropy, and dipole
+moment of monomer units is observed when rigid benzamide fragments are
+introduced into the dendrimers. The backbone conformation of second-generation
+dendrimers containing such fragments is shown to be well described by
+generalized wormlike chain model.",0905.0153v1
+2009-05-11,Orbital-Ordering Induces Structural Phase Transition and the Resistivity Anomaly in Iron Pnictides,"We attribute the structural phase transition (SPT) in the parent compounds of
+the iron pnictides to orbital ordering. Due to the anisotropy of the $d_{xz}$
+and $d_{yz}$ orbitals in the $xy$ plane, a ferro-orbital ordering makes the
+orthorhombic structure more energetically favorable, thus inducing the SPT. In
+this orbital-ordered system, the sites with orbitals that do not order have
+higher energies. Scattering of the itinerant electrons by these localized
+two-level systems causes a resistivity anomaly upon the onset of the SPT. The
+proposed orbital ordering also leads to the stripe-like anti-ferromagnetism and
+anisotropy of the magnetic exchanges. This model is quantitatively consistent
+with available experimental observations.",0905.1704v2
+2009-05-21,Anisotropic dark energy and CMB anomalies,"We investigate the breaking of global statistical isotropy caused by a dark
+energy component with an energy-momentum tensor which has point symmetry, that
+could represent a cubic or hexagonal crystalline lattice. In such models
+Gaussian, adiabatic initial conditions created during inflation can lead to
+anisotropies in the cosmic microwave background whose spherical harmonic
+coefficients are correlated, contrary to the standard assumption. We develop an
+adaptation of the line of sight integration method that can be applied to
+models where the background energy-momentum tensor is isotropic, but whose
+linearized perturbations are anisotropic. We then show how this can be applied
+to the cases of cubic and hexagonal symmetry. We compute quantities which show
+that such models are indistinguishable from isotropic models even in the most
+extreme parameter choices, in stark contrast to models with anisotropic initial
+conditions based on inflation. The reason for this is that the dark energy
+based models contribute to the CMB anistropy via the inegrated Sachs-Wolfe
+effect, which is only relevent when the dark energy is dominant, that is, on
+the very largest scales. For inflationary models, however, the anisotropy is
+present on all scales.",0905.3403v1
+2009-05-29,Ferromagnetic resonance linewidth in ultrathin films with perpendicular magnetic anisotropy,"Transition metal ferromagnetic films with perpendicular magnetic anisotropy
+(PMA) have ferromagnetic resonance (FMR) linewidths that are one order of
+magnitude larger than soft magnetic materials, such as pure iron (Fe) and
+permalloy (NiFe) thin films. A broadband FMR setup has been used to investigate
+the origin of the enhanced linewidth in Ni$|$Co multilayer films with PMA. The
+FMR linewidth depends linearly on frequency for perpendicular applied fields
+and increases significantly when the magnetization is rotated into the film
+plane. Irradiation of the film with Helium ions decreases the PMA and the
+distribution of PMA parameters. This leads to a great reduction of the FMR
+linewidth for in-plane magnetization. These results suggest that fluctuations
+in PMA lead to a large two magnon scattering contribution to the linewidth for
+in-plane magnetization and establish that the Gilbert damping is enhanced in
+such materials ($\alpha \approx 0.04$, compared to $\alpha \approx 0.002$ for
+pure Fe).",0905.4779v2
+2009-06-03,The imprint of the interaction between dark sectors in large scale cosmic microwave background anisotropies,"Dark energy interacting with dark matter is a promising model to solve the
+cosmic coincidence problem. We study the signature of such interaction on large
+scale cosmic microwave background (CMB) temperature anisotropies. Based on the
+detail analysis in perturbation equations of dark energy and dark matter when
+they are in interaction, we find that the large scale CMB, especially the late
+Integrated Sachs Wolfe effect, is a useful tool to measure the coupling between
+dark sectors. We also discuss the possibility to detect the coupling by
+cross-correlating CMB maps with tracers of the large scale structure. We
+finally perform the global fitting to constrain the coupling by using the CMB
+power spectrum data together with other observational data. We find that in the
+$1\sigma$ range, the constrained coupling between dark sectors can solve the
+coincidence problem.",0906.0677v2
+2009-06-04,Sensitivity of Ag/Al Interface Specific Resistances to Interfacial Intermixing,"We have measured an Ag/Al interface specific resistance, 2AR(Ag/Al)(111) =
+1.4 fOhm-m^2, that is twice that predicted for a perfect interface, 50% larger
+than for a 2 ML 50%-50% alloy, and even larger than our newly predicted 1.3
+fOhmm^2 for a 4 ML 50%-50% alloy. Such a large value of 2ARAg/Al(111) confirms
+a predicted sensitivity to interfacial disorder and suggests an interface
+greater than or equal to 4 ML thick. From our calculations, a predicted
+anisotropy ratio, 2AR(Ag/Al)(001)/2AR(Ag/Al)(111), of more then 4 for a perfect
+interface, should be reduced to less than 2 for a 4 ML interface, making it
+harder to detect any such anisotropy.",0906.0934v1
+2009-06-12,Giant magnetic anisotropy changes in Sr2CrReO6 thin films on BaTiO3,"The integration of ferromagnetic and ferroelectric materials into hybrid
+heterostructures yields multifunctional systems with improved or novel
+functionality. We here report on the structural, electronic and magnetic
+properties of the ferromagnetic double perovskite Sr2CrReO6, grown as epitaxial
+thin film onto ferroelectric BaTiO3. As a function of temperature, the
+crystal-structure of BaTiO3 undergoes phase transitions, which induce
+qualitative changes in the magnetic anisotropy of the ferromagnet. We observe
+abrupt changes in the coercive field of up to 1.2T along with resistance
+changes of up to 6.5%. These results are attributed to the high sensitivity of
+the double perovskites to mechanical deformation.",0906.2276v1
+2009-06-15,Subtlety of Determining the Critical Exponent $ν$ of the Spin-1/2 Heisenberg Model with a Spatially Staggered Anisotropy on the Honeycomb Lattice,"Puzzled by the indication of a new critical theory for the spin-1/2
+Heisenberg model with a spatially staggered anisotropy on the square lattice as
+suggested in \cite{Wenzel08}, we study a similar anisotropic spin-1/2
+Heisenberg model on the honeycomb lattice. The critical point where the phase
+transition occurs due to the dimerization as well as the critical exponent
+$\nu$ are analyzed in great detail. Remarkly, using most of the available data
+points in conjunction with the expected finite-size scaling ansatz with a
+sub-leading correction indeed leads to a consistent $\nu = 0.691(2)$ with that
+calculated in \cite{Wenzel08}. However by using the data with large number of
+spins $N$, we obtain $\nu = 0.707(6)$ which agrees with the most accurate Monte
+Carlo O(3) value $\nu = 0.7112(5)$ as well.",0906.2539v3
+2009-06-15,Nonlocal Form of the Rapid Pressure-Strain Correlation in Turbulent Flows,"A new fundamentally-based formulation of nonlocal effects in the rapid
+pressure-strain correlation in turbulent flows has been obtained. The resulting
+explicit form for the rapid pressure-strain correlation accounts for nonlocal
+effects produced by spatial variations in the mean-flow velocity gradients, and
+is derived through Taylor expansion of the mean velocity gradients appearing in
+the exact integral relation for the rapid pressure-strain correlation. The
+integrals in the resulting series expansion are solved for high- and
+low-Reynolds number forms of the longitudinal correlation function $f(r)$, and
+the resulting nonlocal rapid pressure-strain correlation is expressed as an
+infinite series in terms of Laplacians of the mean strain rate tensor. The new
+formulation is used to obtain a nonlocal transport equation for the turbulence
+anisotropy that is expected to provide improved predictions of the anisotropy
+in strongly inhomogeneous flows.",0906.2755v1
+2009-06-21,Magnetotransport properties in purple bronze Li$_{0.9}$Mo$_6$O$_{17}$ Single Crystal,"We have measured resistivity along the a, b and c axes of
+Li$_{0.9}$Mo$_6$O$_{17}$ single crystal. The anisotropy $\rho$$_c$ / $\rho$$_a$
+and $\rho$$_c$ / $\rho$$_b$ is given, confirming the quasi-one-dimensionality
+of the compound. The sharp decrease in the anisotropy below a certain
+temperature (T$_M$) indicates dimensional crossover. Superconductivity occurs
+at 1.8 K well below $T_M$. Negative MRs are observed with magnetic field (H)
+applied along b axis. This could be ascribed to suppression of energy gap
+associated with CDW state. While large positive MR is observed with H
+$\parallel$ c-axis. The MR data can be well fitted by a modified two-band model
+which has been used in CDW compounds such as quasi-two-dimensional purple
+bronzes A$_{0.9}$Mo$_6$O$_{17}$ (A = K, Na, Tl) and quasi-one-dimensional
+conductor NbSe$_3$. The behavior of MR provides a strong evidence for the
+existence of CDW instability in $Li_{0.9}Mo_6O_{17}$.",0906.3855v1
+2009-06-26,The Role of Anisotropy in the Void Models without Dark Energy,"Void models provide a possible explanation of the ""accelerated expansion"" of
+the Universe without dark energy. To make the conventional void models more
+realistic, we allow the void, an underdense region around us, to be anisotropic
+and consider an average of the distance-redshift relations over the solid angle
+subtended at the observer. We first show that after taking the average of a
+form of the optical scalar equation (distance equation), the effective distance
+equation we obtain coincides with the one for the Lemaitre-Tolman-Bondi
+universe with a Dyer-Roeder-like extension. We then numerically solve the
+equation to compare with observational data of Type Ia supernovae. We find that
+anisotropy allows smaller size of void and larger Omega_m.",0906.4857v1
+2009-06-26,Density and kinematic cusps in M54 at the heart of the Sagittarius dwarf galaxy: evidence for a 10^4 M_sun Black Hole?,"We report the detection of a stellar density cusp and a velocity dispersion
+increase in the center of the globular cluster M54, located at the center of
+the Sagittarius dwarf galaxy (Sgr). The central line of sight velocity
+dispersion is 20.2 +/- 0.7 km/s, decreasing to 16.4 +/- 0.4 km/s at 2.5"" (0.3
+pc). Modeling the kinematics and surface density profiles as the sum of a King
+model and a point-mass yields a black hole (BH) mass of ~ 9400 M_sun. However,
+the observations can alternatively be explained if the cusp stars possess
+moderate radial anisotropy. A Jeans analysis of the Sgr nucleus reveals a
+strong tangential anisotropy, probably a relic from the formation of the
+system.",0906.4894v1
+2009-07-11,Large scale alignment anomalies of CMB anisotropies: a new test for residuals applied to WMAP 5yr maps,"We analyze the alignment of the low multipoles (quadrupole and octupole) of
+various maps of the WMAP 5yr release: the CMB maps obtained with ILC and MCMC
+methods, the CMB map in the V band after foreground reduction, and, for
+comparison, the (not cleaned) V band map. We study how much this alignment is
+polluted by residuals on the Galactic region. Among the considered maps, the
+WMAP-ILC turns out to be the most clean map from the point of view of the
+proposed test. This result has been found studying the redistribution (due to
+the masking process) of each bin of the probability distribution functions of
+the alignment estimators. By construction, our method, feasible through Monte
+Carlo simulations, works for any possible mask adopted in the analysis of data
+from current and forthcoming CMB anisotropy experiments and it can only exclude
+that the considered map is clean.",0907.1949v1
+2009-07-20,Liquid n-hexane condensed in silica nanochannels: A combined optical birefringence and vapor sorption isotherm study,"The optical birefringence of liquid n-hexane condensed in an array of
+parallel silica channels of 7nm diameter and 400 micrometer length is studied
+as a function of filling of the channels via the vapor phase. By an analysis
+with the generalized Bruggeman effective medium equation we demonstrate that
+such measurements are insensitive to the detailed geometrical (positional)
+arrangement of the adsorbed liquid inside the channels. However, this technique
+is particularly suitable to search for any optical anisotropies and thus
+collective orientational order as a function of channel filling. Nevertheless,
+no hints for such anisotropies are found in liquid n-hexane. The n-hexane
+molecules in the silica nanochannels are totally orientationally disordered in
+all condensation regimes, in particular in the film growth as well as in the
+the capillary condensed regime. Thus, the peculiar molecular arrangement found
+upon freezing of liquid n-hexane in nanochannel-confinement, where the
+molecules are collectively aligned perpendicularly to the channels' long axes,
+does not originate in any pre-alignment effects in the nanoconfined liquid due
+to capillary nematization.",0907.3484v1
+2009-07-20,A new collective phenomenon arising from spin anisotropic perturbations to a Heisenberg square lattice manifested in paramagnetic resonance experiments,"We report unexpected behaviour in a family of Cu spin- 1/2 systems, in which
+an apparent gap in the low energy magneto-optical absorption spectrum opens at
+low temperature. This previously unreported collective phenomenon arises at
+temperatures where the energy of the dominant exchange interaction exceeds the
+thermal energy. Simulations of the observed shifts in electron paramagnetic
+resonance spectral weight, which include spin anisotropy, reproduce this
+behavior yielding the magnitude of the spin anisotropy in these compounds.",0907.3514v2
+2009-07-23,On Possible Variation in the Cosmological Baryon Fraction,"The fraction of matter that is in the form of baryons or dark matter could
+have spatial fluctuations in the form of baryon-dark matter isocurvature
+fluctuations. We use big bang nucleosynthesis calculations compared with
+observed light element abundances as well as galaxy cluster gas fractions to
+constrain cosmological variations in the baryon fraction. Light element
+abundances constrain spatial variations to be less than 26-27%, while a sample
+of ""relaxed"" galaxy clusters shows spatial variations in gas fractions less
+than 8%. Larger spatial variations could cause differential screening of the
+primary cosmic microwave background anisotropies, leading to asymmetries in the
+fluctuations and ease some tension with the halo-star 7Li abundance.
+Fluctuations within our allowed bounds can lead to ""B-mode"" CMB polarization
+anisotropies at a non-negligible level.",0907.3919v2
+2009-07-23,Quantum Phase Transition in Hall Conductivity on an Anisotropic Kagome Lattice,"We study the quantum Hall effect(QHE) on the Kagom\'{e} lattice with
+anisotropy in one of the hopping integrals. We find a new type of QHE
+characterized by the quantization rules for Hall conductivity
+$\sigma_{xy}=2ne^{2}/h$ and Landau Levels $E(n)=\pm v_{F}\sqrt{(n+1/2)\hbar
+Be}$ ($n$ is an integer), which is different from any known type. This phase
+evolves from the QHE phase with $\sigma_{xy}=4(n+1/2)e^{2}/h$ and $E(n)=\pm
+v_{F}\sqrt{2n\hbar Be}$ in the isotropic case, which is realized in a system
+with massless Dirac fermions (such as in graphene). The phase transition does
+not occur simultaneously in all Hall plateaus as usual but in sequence from low
+to high energies, with the increase of hopping anisotropy.",0907.4023v1
+2009-07-27,Electronic and phononic Raman scattering in detwinned YBa$_2$Cu$_3$O$_{6.95}$ and Y$_{0.85}$Ca$_{0.15}$Ba$_2$Cu$_3$O$_{6.95}$: s-wave admixture to the $d_{x^2-y^2}$-wave order parameter,"Inelastic light (Raman) scattering has been used to study electronic
+excitations and phonon anomalies in detwinned, slightly overdoped
+YBa$_2$Cu$_3$O$_{6.95}$ and moderately overdoped
+Y$_{0.85}$Ca$_{0.15}$Ba$_2$Cu$_3$O$_{6.95}$ single crystals. In both samples
+modifications of the electronic pair-breaking peaks when interchanging the a-
+and b-axis were observed. The lineshapes of several phonon modes involving
+plane and apical oxygen vibrations exhibit pronounced anisotropies with respect
+to the incident and scattered light field configurations. Based on a
+theoretical model that takes both electronic and phononic contributions to the
+Raman spectra into account, we attribute the anisotropy of the
+superconductivity-induced changes in the phonon lineshapes to a small s-wave
+admixture to the $d_{x^2-y^2}$ pair wave-function. Our theory allows us to
+disentangle the electronic Raman signal from the phononic part and to identify
+corresponding interference terms. We argue that the Raman spectra are
+consistent with an s-wave admixture with an upper limit of 20 percent.",0907.4587v1
+2009-08-01,Magnetic solitons in frustrated ferromagnetic spin chain,"We study the classical anisotropic ferromagnetic spin chain with frustration.
+The behavior of soliton and kink solutions in the vicinity of the ground state
+phase transition from the ferromagnetic to the spiral phase is studied. The
+dependence of the soliton energy on small anisotropy parameter is established
+using scaling estimates and numerical minimization of the energy functional.
+Conditions of the existence of the solitons are determined. It is shown that
+solitons survive in the spiral phase though with some restrictions on their
+size. A comparison of the energies of the classical solitons and the bound
+magnon complexes in the quantum model shows the functional similarity between
+them. The influence of the finite-size effects on the soliton states is studied
+and it is shown that the localized solitons originate from the uniform state
+when the system size exceeds some critical value depending on the anisotropy.",0908.0068v1
+2009-08-04,Galaxy distribution and evolution around a sample of 2dF groups,"We study galaxy evolution and spatial patterns in the surroundings of a
+sample of 2dF groups. Our aim is to find evidence of galaxy evolution and
+clustering out to 10 times the virial radius of the groups and so redefine
+their properties according to the spatial patterns in the fields and relate
+them to galaxy evolution. Group members and interlopers were redefined after
+the identification of gaps in the redshift distribution. We then used
+exploratory spatial statistics based on the second moment of the Ripley
+function to probe the anisotropy in the galaxy distribution around the groups.
+We found an important anticorrelation between anisotropy and the fraction of
+early-type galaxies in these fields. Our results illustrate how the dynamical
+state of galaxy groups can be ascertained by the systematic study of their
+neighborhoods.This is an important achievement, since the correct estimate of
+the extent to which galaxies are affected by the group environment and follow
+large-scale filamentary structure is relevant to understanding the process of
+galaxy clustering and evolution in the Universe.",0908.0517v2
+2009-08-06,Skymap for atmospheric muons at TeV energies measured in deep-sea neutrino telescope ANTARES,"Recently different experiments mention to have observed a large scale
+cosmic-ray anisotropy at TeV energies, e.g. Milagro, Tibet and
+Super-Kamiokande. For these energies the cosmic-rays are expected to be nearly
+isotropic. Any measurements of cosmic-rays anisotropy could bring some
+information about propagation and origin of cosmic-rays. Though the primary aim
+of the ANTARES neutrino telescope is the detection of high energy cosmic
+neutrinos, the detector measures mainly down-doing muons, which are decay
+products of cosmic-rays collisions in the Earth's atmosphere. This proceeding
+describes an anlaysis method for the first year measurement of down-going
+atmospheric muons at TeV energies in the ANTARES experiment, when five out of
+the final number of twelve lines were taking data.",0908.0858v1
+2009-08-12,Detectability of the 21 cm-CMB cross-correlation from the EoR,"The 21-cm line fluctuations and the cosmic microwave background (CMB) are
+powerful probes of the epoch of reionisation of the universe. We study the
+potential of the cross-correlation between 21-cm line fluctuations and CMB
+anisotropy to obtain further constraints on the reionisation history. We
+compute analytically the 21-cm cross-correlation with the CMB temperature
+anisotropy and polarisation, and we calculate the signal-to-noise (SN) ratio
+for its detection with Planck together with LOFAR, MWA and SKA. We find, on the
+one hand, that the 21-cm cross-correlation signal with CMB polarisation from
+the instant reionisation can be detected with an SN ratio of $\sim 1$ for LOFAR
+and $\sim 10$ for SKA. On the other hand, we confirm that the detection of the
+21-cm cross-correlation with CMB polarisation is practically infeasible.",0908.1632v2
+2009-08-17,Evolution of magnetic states in frustrated diamond lattice antiferromagnetic Co(Al1-xCox)2O4 spinels,"Using neutron powder diffraction and Monte-Carlo simulations we show that a
+spin-liquid regime emerges at $all compositions in the diamond-lattice
+antiferromagnets Co(Al1-xCox)2O4. This spin-liquid regime induced by
+frustration due to the second-neighbour exchange coupling J2, is gradually
+superseded by antiferromagnetic collinear long-range order (k=0) at low
+temperatures. Upon substitution of Al3+ by Co3+ in the octahedral B-site the
+temperature range occupied by the spin-liquid regime narrows and TN increases.
+To explain the experimental observations we considered magnetic anisotropy D or
+third-neighbour exchange coupling J3 as degeneracy-breaking perturbations. We
+conclude that Co(Al1-xCox)2O4 is below the theoretical critical point
+J2/J1=1/8, and that magnetic anisotropy assists in selecting a collinear
+long-range ordered ground state, which becomes more stable with increasing x
+due to a higher efficiency of O-Co3+-O as an interaction path compared to
+O-Al3+-O.",0908.2318v2
+2009-08-23,Upper critical fields and critical current density of BaFe2(As0.68P0.32)2 single crystal,"The transport properties, upper critical fields, superconducting anisotropy,
+and critical current density in an iso-valent phosphorus-doped BaFe2As2 single
+crystal close to optimum doping are investigated in this report. Temperature
+dependent resistivity and susceptibility show a superconducting transition
+temperature, Tc, just below 31 K both with sharp transitions. The upper
+critical field parallel to the ab-plane, Hc2^ab, is above 77 Tesla while that
+along the c-axis direction, Hc2^c, is just above 36 Tesla, yielding a low
+superconducting anisotropy ratio ~ 2. The estimated inter-plane coherence
+length based on the Ginzburg-Landau (G-L) theory indicates BaFe2(As0.68P0.32)2
+is still above the point for a dimensional crossover inferring the
+superconducting layers are not weakly-coupled in this system. The critical
+current density at 5 K obtained from magnetization loops measurement show a
+modest Jc as high as 10^5 A/cm2.",0908.3284v2
+2009-08-27,"Soft x-ray magnetic circular dichroism of LaCoO$_{3}$, La$_{0.7}$Ce$_{0.3}$CoO$_{3}$, and La$_{0.7}$Sr$_{0.3}$CoO$_{3}$ films: Evidence for Co valency-dependent magnetism and magnetic anisotropy","Epitaxial thin films of undoped LaCoO$_{3}$\@, of electron-doped
+La$_{0.7}$Ce$_{0.3}$CoO$_{3}$\@, and of hole-doped
+La$_{0.7}$Sr$_{0.3}$CoO$_{3}$\@ exhibit ferromagnetic order with a transition
+temperature $T_{\rm{C}}$ $\approx$ 85 K, 22 K, and 240 K, respectively. The
+spin-state structure for these compounds was studied by soft x-ray magnetic
+circular dichroism at the Co $L_{2,3}$ and O $K$ edges. It turns out that a
+higher spin state of the Co$^{3+}$ ions is responsible for the magnetism in
+LaCoO$_{3}$\@ while for La$_{0.7}$Ce$_{0.3}$CoO$_{3}$ the Co$^{3+}$ ions are in
+a low-spin state and the ferromagnetism is predominantly determined by
+Co$^{2+}$\@. For La$_{0.7}$Sr$_{0.3}$CoO$_{3}$\@, on the other hand, the
+magnetism originates from higher spin states of Co$^{3+}$ and Co$^{4+}$\@.
+Moreover, a strong magnetic anisotropy is observed for all systems.",0908.4015v1
+2009-08-28,Polarization of bremsstrahlung at electron scattering in an anisotropic medium,"Bremsstrahlung from relativistic electrons is considered under conditions
+when some transverse direction of momentum transfer is statistically preferred.
+It is shown that in the dipole approximation all the medium anisotropy effects
+can be accumulated into a special modulus-bound transverse vector, $\bm N$. To
+exemplify a target with $N^2\sim1$, we calculate radiation from electron
+incident at a small angle on an atomic row in oriented crystal. Radiation
+intensity and polarization dependence on the emission angle and frequency for
+constant $\bm N$ is investigated. Net polarization for the angle-integral
+cross-section is evaluated, which appears to be proportional to $N^2/2$, and
+decreases with the increase of the photon energy fraction. A prominent feature
+of the radiation angular distribution is the existence of an angle at which the
+radiation may be completely polarized, in spite of the target complete or
+partial isotropy -- that owes to existence of an origin-centered tangential
+circle for polarization in the fully differential radiation probability kernel.
+Possibilities for utilizing various properties of the polarized bremsstrahlung
+flux for preparation of polarized photon beams and for probing intrinsic
+anisotropy of the medium are analyzed.",0908.4237v3
+2009-08-31,Lorentz microscopy mapping for domain walls structure study in L1$_0$ FePd thin films,"Thin film alloys with perpendicular anisotropy were studied using Lorentz
+Transmission Electron Microscopy (LTEM). This work focuses on the configuration
+of domain walls and demonstrates the suitability and accuracy of LTEM for the
+magnetic characterisation of perpendicular magnetic anisotropy materials. Thin
+films of chemically ordered ($\unit{L1_0}$) FePd alloys were investigated by
+micro-magnetic modelling and LTEM phase retrieval approach. The different
+components of magnetization described by the modeling were studied on
+experimental images and confirmed by LTEM contrast simulation. Furthermore,
+quantitative measurements of magnetic induction inside the domain walls were
+made by using an original method to separate the electrical and magnetical
+contributions to the phase information. Irregularities were also observed along
+the domain walls which could play a major role during the magnetization
+processes.",0908.4463v1
+2009-09-01,"Inflation, quantum fields, and CMB anisotropies","Inflationary cosmology has proved to be the most successful at predicting the
+properties of the anisotropies observed in the cosmic microwave background
+(CMB). In this essay we show that quantum field renormalization significantly
+influences the generation of primordial perturbations and hence the expected
+measurable imprint of cosmological inflation on the CMB. However, the new
+predictions remain in agreement with observation, and in fact favor the
+simplest forms of inflation. In the near future, observations of the influence
+of gravitational waves from the early universe on the CMB will test our new
+predictions.",0909.0026v1
+2009-09-03,Thermalization through parton transport,"A radiative transport model is used to study kinetic equilibration during the
+early stage of a relativistic heavy ion collision. The parton system is found
+to be able to overcome expansion and move toward thermalization via parton
+collisions. Scaling behaviors show up in both the pressure anisotropy and the
+energy density evolutions. In particular, the pressure anisotropy evolution
+shows an approximate alpha_s scaling when radiative processes are included. It
+approaches an asymptotic time evolution on a time scale of 1 to 2 fm/c. The
+energy density evolution shows an asymptotic time evolution that decreases
+slower than the ideal hydro evolution. These observations indicate that partial
+thermalization can be achieved and viscosity is important for the evolution
+during the early longitudinal expansion stage of a relativistic heavy ion
+collision.",0909.0780v1
+2009-09-04,Magnetic anisotropy of singly Mn-doped InAs/GaAs quantum dots,"We report on the micro-photoluminescence spectroscopy of InAs/GaAs quantum
+dots (QD) doped by a single Mn atom in a magnetic field either longitudinal or
+perpendicular to the optical axis. In both cases the spectral features of
+positive trion (X+) are found to split into strongly circularly polarized
+components, an effect very surprising in a perpendicular magnetic field. The
+field-induced splitting is ascribed to the transverse Zeeman splitting of the
+neutral acceptor complex A0 issued by the Mn impurity, whereas the circular
+optical selection rules result from the p-d exchange which acts as a very
+strong longitudinal magnetic field inhibiting the spin mixing by the transverse
+field of the QD heavy-hole ground state. A theoretical model of the spin
+interactions which includes (i) the local strain anisotropy experienced by the
+acceptor level and (ii) the anisotropic exchange due to the out-of-center Mn
+position provides a very good agreement with our observations.",0909.0877v1
+2009-09-19,The Impact of Secondary non-Gaussianities in the CMB on Cosmological Parameter Estimation,"We consider corrections to the underlying cosmology due to secondary
+contributions from weak gravitational lensing, the integrated Sachs-Wolfe
+effect, and the Sunyaev-Zel'dovich effect contained in the trispectrum. We
+incorporate these additional contributions to the covariance of a binned
+angular power spectrum of temperature anisotropies in the analysis of current
+and prospective data sets. Although recent experiments such as ACBAR and CBI
+are not particularly sensitive to these additional non-Gaussian effects, the
+interpretation of Planck and CMBPol anisotropy spectra will require an
+accounting of non-Gaussian covariance leading to a degradation in cosmological
+parameter estimates by up to 20% and 30%, respectively.",0909.3515v3
+2009-09-19,New Constraints on variations of the fine structure constant from CMB anisotropies,"We demonstrate that recent measurements of Cosmic Microwave Background
+temperature and polarization anisotropy made by the ACBAR, QUAD and BICEP
+experiments substantially improve the cosmological constraints on possible
+variations of the fine structure constant in the early universe. This data,
+combined with the five year observations from the WMAP mission yield the
+constraint alpha/alpha_0 = 0.987 \pm 0.012 at 68% c.l.. The inclusion of the
+new HST constraints on the Hubble constant further increases the accuracy to
+alpha/alpha_0 = 1.001 \pm 0.007 at 68% c.l., bringing possible deviations from
+the current value below the 1% level and improving previous constraints by a
+factor 3.",0909.3584v1
+2009-09-23,"Identified particle production, azimuthal anisotropy, and interferometry measurements in Au+Au collisions at $\sqrt{s_{NN}}$ = 9.2 GeV","We present the first measurements of identified hadron production, azimuthal
+anisotropy, and pion interferometry from Au+Au collisions below the nominal
+injection energy at the Relativistic Heavy-Ion Collider (RHIC) facility. The
+data were collected using the large acceptance STAR detector at $\sqrt{s_{NN}}$
+= 9.2 GeV from a test run of the collider in the year 2008. Midrapidity results
+on multiplicity density (dN/dy) in rapidity (y), average transverse momentum
+(<pT>), particle ratios, elliptic flow, and HBT radii are consistent with the
+corresponding results at similar $\sqrt{s_{NN}}$ from fixed target experiments.
+Directed flow measurements are presented for both midrapidity and forward
+rapidity regions. Furthermore the collision centrality dependence of identified
+particle dN/dy, <pT>, and particle ratios are discussed. These results also
+demonstrate the readiness of the STAR detector to undertake the proposed QCD
+critical point search and the exploration of the QCD phase diagram at RHIC.",0909.4131v2
+2009-10-09,"Non-Euclidean statistics for covariance matrices, with applications to diffusion tensor imaging","The statistical analysis of covariance matrix data is considered and, in
+particular, methodology is discussed which takes into account the non-Euclidean
+nature of the space of positive semi-definite symmetric matrices. The main
+motivation for the work is the analysis of diffusion tensors in medical image
+analysis. The primary focus is on estimation of a mean covariance matrix and,
+in particular, on the use of Procrustes size-and-shape space. Comparisons are
+made with other estimation techniques, including using the matrix logarithm,
+matrix square root and Cholesky decomposition. Applications to diffusion tensor
+imaging are considered and, in particular, a new measure of fractional
+anisotropy called Procrustes Anisotropy is discussed.",0910.1656v1
+2009-10-12,Dirac-Born-Infeld and k-inflation: the CMB anisotropies from string theory,"Inflationary models within string theory exhibit unusual scalar field
+dynamics involving non-minimal kinetic terms and generically referred to as
+k-inflation. In this situation, the standard slow-roll approach used to
+determine the behavior of the primordial cosmological perturbations cannot
+longer be used. We present a generic method, based on the uniform
+approximation, to analytically derive the primordial power spectra of scalar
+and tensor perturbations. At leading order, the scalar spectral index, its
+running and the tensor-to-scalar ratio are modified by the new dynamics. We
+provide their new expression, correct previous results at next-to-leading order
+and clarify the definition of what is the tensor-to-scalar ratio when the sound
+horizon and Hubble radius are not the same. Finally, we discuss the constraints
+the parameters encoding the non-minimal kinetic terms have to satisfy, such as
+the sound speed and the energy scale of k-inflation, in view of the fifth year
+Wilkinson Microwave Anisotropy Probe (WMAP5) data.",0910.2167v1
+2009-10-16,Estimates of hadron azimuthal anisotropy from multiparton interactions in proton-proton collisions at sqrt(s) = 14 TeV,"We estimate the amount of collective ""elliptic flow"" expected at mid-rapidity
+in proton-proton (p-p) collisions at the CERN Large Hadron Collider (LHC),
+assuming that any possible azimuthal anisotropy of the produced hadrons with
+respect to the plane of the reaction follows the same overlap-eccentricity and
+particle-density scalings as found in high-energy heavy ion collisions. Using a
+Glauber eikonal model, we compute the p-p eccentricities, transverse areas and
+particle-multiplicities for various phenomenological parametrisations of the
+proton spatial density. For realistic proton transverse profiles, we find
+integrated elliptic flow v2 parameters below 3% in p-p collisions at sqrt(s) =
+14 TeV.",0910.3029v3
+2009-10-22,Consequences of the peculiar intrinsic properties of MgB2 on its macroscopic current flow,"The influence of two important features of magnesium diboride on the
+macroscopic transport properties of polycrystalline MgB2 is discussed in the
+framework of a percolation model. While two band superconductivity does not
+have significant consequences in the field and temperature range of possible
+power applications, the opposite is true for the anisotropy of the upper
+critical field. The field dependence of the critical current densities strongly
+increases and the macroscopic supercurrents disappear well below the apparent
+upper critical field. The common scaling laws for the field dependence of the
+volume pinning force are altered and Kramer's plot is no longer linear,
+although grain boundary pinning dominates in nearly all polycrystalline MgB2
+conductors. In contrast to the conventional superconductors NbTi and Nb3Sn, a
+significant critical current anisotropy can be induced by the preparation
+technique of MgB2 tapes.",0910.4316v1
+2009-10-23,Morphological evolution of edge-hillocks on single crystal films having anisotropic drift-diffusion under the capillary and electromigration forces,"The morphological evolution of hillocks at the unpassivated sidewalls of the
+single crystal metallic thin films is investigated via computer simulations by
+using the free-moving boundary value problem. The effects of the
+drift-diffusion anisotropy on the development of surface topographical
+scenarios is fully explored under the action of electromigration and capillary
+forces, utilizing numerous combination of the surface texture, the
+drift-diffusion anisotropy and the direction of the applied electric field. The
+present simulation studies yield very rich and technologically imported
+information, in regards to the critical texture of the single crystal thin film
+surfaces, and the intensity and the orientation of the applied electric field,
+as far as the device reliability is concerned.",0910.4596v1
+2009-10-27,Differences at low l in Planck's first light sky map of the cosmic microwave background from WMAP's and COBE's,"The recent release of the first light sky map of the cosmic microwave
+background (CMB) from the Planck satellite provides an initial opportunity for
+comparison with the WMAP and COBE sky maps and their reconstruction algorithms.
+The precision of the match between Planck's and WMAP's anisotropies below
+several degrees in size, which corresponds to spherical harmonics with high l,
+provides confidence that the differences between the anisotropies at low l are
+substantial. If the Planck first light sky map is taken as the gold standard,
+the results seem to suggest the low l components of the WMAP map and a
+considerable part of the COBE sky map have a similar reconstruction artefact.
+As the Planck first light sky map covers only about 10% of the sky, any
+conclusions drawn from this comparison are speculative but deserving of further
+investigation.",0910.5102v3
+2009-10-28,Quantum field theoretical study of an effective spin model in coupled optical cavity arrays,"Atoms trapped in microcavities and interacting through the exchange of
+virtual photons can model an anisotropic Heisenberg spin-1/2 lattice.
+  We do the quantum field theoretical study of such a system using the Abelian
+bosonization method followed by the renormalization group analysis. We present
+interesting physics due to the presence of exchange anisotropy. An infinite
+order Kosterliz-Thouless-Berezinskii transition is replaced by second order XY
+transition even an infinitesimal a small anisotropy in exchange coupling is
+introduced. We predict a quantum phase transition between Mott insulating and
+photonic superfluid phase due to detuning between the cavity and laser
+frequency, a large detuning favours the photonic superfluid phase. We also do
+the analysis of Jaynes and Cumming Hamiltonian to support results of quantum
+field theoretical study.",0910.5341v1
+2009-10-29,Anisotropic order parameter in Li-intercalated layered superconductor Li$_x$ZrNCl,"In this study, it is shown that in a layered nitride superconductor, i.e.,
+LixZrNCl (0.07<=x<=0.21), the superconducting order parameter is highly
+anisotropic in a sample with x=0.12, as inferred from both the temperature and
+the magnetic field dependences of the muon depolarization rate (sigma_s,
+proportional to the superfluid density). Moreover, the tendency of strong
+anisotropy with an increase in x is indicated by the T dependence of sigma_s.
+These observations are in good agreement with the recent theory that predicts
+the development of anisotropy in a d+id' gap upon carrier filling to the bands
+with disconnected Fermi surfaces on a honeycomb lattice.",0910.5557v2
+2009-11-02,Inverse Spin-Galvanic Effect in a Topological-Insulator/Ferromagnet Interface,"When a ferromagnet is deposited on the surface of a topological insulator the
+topologically protected surface state develops a gap and becomes a
+2-dimensional quantum Hall liquid. We demonstrate that the Hall current in such
+a liquid, induced by an external electric field, can have a large effect on the
+magnetization dynamics of the ferromagnet by changing the effective anisotropy
+field. This change is dissipationless and may be substantial even in weakly
+spin-orbit coupled ferromagnets. We study the possibility of dissipationless
+current-induced magnetization reversal in monolayer-thin, insulating
+ferromagnets with a soft perpendicular anisotropy and discuss possible
+applications of this effect.",0911.0106v1
+2009-11-06,CMB temperature trispectrum of cosmic strings,"We provide an analytical expression for the trispectrum of the Cosmic
+Microwave Background (CMB) temperature anisotropies induced by cosmic strings.
+Our result is derived for the small angular scales under the assumption that
+the temperature anisotropy is induced by the Gott-Kaiser-Stebbins effect. The
+trispectrum is predicted to decay with a non-integer power-law exponent l^(-r)
+with 6<r<7, depending on the string microstructure, and thus on the string
+model. For Nambu-Goto strings, this exponent is related to the string mean
+square velocity and the loop distribution function. We then explore two classes
+of wavenumber configuration in Fourier space, the kite and trapezium
+quadrilaterals. The trispectrum can be of any sign and appears to be strongly
+enhanced for all squeezed quadrilaterals.",0911.1241v2
+2009-11-12,An ac field probe for the magnetic ordering of magnets with random anisotropy,"A Monte Carlo simulation is carried out to investigate the magnetic ordering
+in magnets with random anisotropy (RA). Our results show peculiar similarities
+to recent experiments that the real part of ac susceptibility presents two
+peaks for weak RA and only one for strong RA regardless of glassy critical
+dynamics manifested for them. We demonstrate that the thermodynamic nature of
+the low-temperature peak is a ferromagnetic-like dynamic phase transition to
+quasi-long range order (QLRO) for the former. Our simulation, therefore, is
+able to be incorporated with the experiments to help clarify the existence of
+the QLRO theoretically predicted so far.",0911.2352v1
+2009-11-19,Simple Types of Anisotropic Inflation,"We display some simple cosmological solutions of gravity theories with
+quadratic Ricci curvature terms added to the Einstein-Hilbert lagrangian which
+exhibit anisotropic inflation. The Hubble expansion rates are constant and
+unequal in three orthogonal directions. We describe the evolution of the
+simplest of these homogeneous and anisotropic cosmological models from its
+natural initial state and evaluate the deviations they will create from
+statistical isotropy in the fluctuations produced during a period of
+anisotropic inflation. The anisotropic inflation is not a late-time attractor
+in these models but the rate of approach to a final isotropic de Sitter state
+is slow and is conducive to the creation of observable anisotropic statistical
+effects in the microwave background. The statistical anisotropy would not be
+scale invariant and the level of statistical anisotropy will grow with scale.",0911.3805v2
+2009-11-23,Magnetic properties of the quasi-two-dimensional S = 1/2 Heisenberg antiferromagnet [Cu(pyz)2(HF2)]PF6,"We report on high-field magnetization, specific-heat and electron spin
+resonance (ESR) studies of the quasi-two-dimensional spin-1/2 Heisenberg
+antiferromagnet [Cu(pyz)2(HF2)]PF6. The frequency-field diagram of ESR modes
+below TN = 4.38 K is described in the frame of the meanfield theory, confirming
+a collinear magnetic structure with an easy-plane anisotropy. The obtained
+results allowed us to determine the anisotropy/exchange interaction ratio, A/J
+= 0.003, and the upper limit for the inter/intra-plane exchange-interaction
+ratio, J'/J = 1/16. It is argued that despite the onset of 3D long-range
+magnetic ordering the magnetic properties of this material (including
+high-magnetic-field magnetization and non-monotonic field dependence of the
+Neel temperature) are strongly affected by two-dimensional spin correlations.",0911.4402v1
+2009-11-30,Frustrated local moment models for Fe-pnictide magnetism,"The low energy spin excitations of the Fe pnictide parent compounds have been
+determined by inelastic neutron scattering and interpreted within the local
+moment J_1a,b-J_2 Heisenberg model with orthorhombic symmetry. This has led to
+alternative exchange models that strongly differ in the size of anisotropy.
+Although the compounds are itinerant the localised spin model can explain basic
+features of the excitations. The inherent frustration of this model leads to
+quantum fluctuations and possible moment reduction. We investigate this
+question in detail using spin wave approximation and partly exact
+diagonalisation Lanczos calculations for finite clusters. We find that the
+orthorhombic anisotropy stabilizes the columnar AF phase and its moment. For
+the exchange models proposed from inelastic neutron scattering we can exclude a
+strong influcence of frustration on the moment size. We also investigate
+dependence of magnetisation and susceptibility on field and temperature.",0911.5664v2
+2009-12-02,Dark Matter tested with satellites,"Recently, the distribution of velocity dispersion as far as 400kpc around red
+isolated galaxies was derived from statistical studies of satellites in the
+SDSS (Klypin & Prada 2009). This could help to constrain dark matter models at
+intermediate scales. We compare the predictions of different DM distributions,
+LCDM with NFW or cored profiles, and also modified gravity models, with
+observations. It is shown how the freedom in the various parameters (radial
+distribution of satellites, velocity anisotropy, external field effect),
+prevents to disentangle the models, which all can give pretty good fits to the
+data. In all cases, realistic radial variations of velocity anisotropy are used
+for the satellites, and a constant stellar-mass to light ratio for the host
+galaxies.",0912.0332v1
+2009-12-03,C-axis critical current of a PrFeAsO0.7 single crystal,"The c-axis transport properties of a high-pressure synthesized PrFeAsO0.7
+single crystal are studied using s-shaped junctions. Resistivity anisotropy of
+about 120 detected at 50 K shows the presence of strong anisotropy in the
+electronic states. The obtained critical current density for the c-axis of
+2.9*10^5 A/cm^2 is two orders of magnitude larger than that in
+Bi2Sr1.6La0.4CuO6+d. The appearance of a hysteresis in the current-voltage
+curve below T_c is the manifestation of the intrinsic Josephson effect similar
+to that in cuprate superconductors. The suppression of the critical
+current-normal resistance (I_cR_n) product is explained by an inspecular
+transport in s_pm-wave pair potential.",0912.0598v1
+2009-12-06,The Correlation Functions of the XXZ Heisenberg Chain for Zero or Infinite Anisotropy and Random Walks of Vicious Walkers,"The XXZ Heisenberg chain is considered for two specific limits of the
+anisotropy parameter: $\Dl\to 0$ and $\Dl\to -\infty$. The corresponding wave
+functions are expressed by means of the symmetric Schur functions. Certain
+expectation values and thermal correlation functions of the ferromagnetic
+string operators are calculated over the base of N-particle Bethe states. The
+thermal correlator of the ferromagnetic string is expressed through the
+generating function of the lattice paths of random walks of vicious walkers. A
+relationship between the expectation values obtained and the generating
+functions of strict plane partitions in a box is discussed. Asymptotic estimate
+of the thermal correlator of the ferromagnetic string is obtained in the limit
+of zero temperature. It is shown that its amplitude is related to the number of
+plane partitions.",0912.1138v2
+2009-12-09,Dimensional phase transitions in small Yukawa clusters,"We investigate the one- to two-dimensional zigzag transition in clusters
+consisting of a small number of particles interacting through a Yukawa (Debye)
+potential and confined in a two-dimensional biharmonic potential well. Dusty
+(complex) plasma clusters with $n \le 19$ monodisperse particles are
+characterized experimentally for two different confining wells. The well
+anisotropy is accurately measured, and the Debye shielding parameter is
+determined from the longitudinal breathing frequency. Debye shielding is shown
+to be important. A model for this system is used to predict equilibrium
+particle configurations. The experiment and model exhibit excellent agreement.
+The critical value of $n$ for the zigzag transition is found to be less than
+that predicted for an unshielded Coulomb interaction. The zigzag transition is
+shown to behave as a continuous phase transition from a one-dimensional to a
+two-dimensional state, where the state variables are the number of particles,
+the well anisotropy and the Debye shielding parameter. A universal critical
+exponent for the zigzag transition is identified for transitions caused by
+varying the Debye shielding parameter.",0912.1650v1
+2009-12-09,Dual Behavior of Antiferromagnetic Uncompensated Spins in NiFe/IrMn Exchange Biased Bilayers,"We present a comprehensive study of the exchange bias effect in a model
+system. Through numerical analysis of the exchange bias and coercive fields as
+a function of the antiferromagnetic layer thickness we deduce the absolute
+value of the averaged anisotropy constant of the antiferromagnet. We show that
+the anisotropy of IrMn exhibits a finite size effect as a function of
+thickness. The interfacial spin disorder involved in the data analysis is
+further supported by the observation of the dual behavior of the interfacial
+uncompensated spins. Utilizing soft x-ray resonant magnetic reflectometry we
+have observed that the antiferromagnetic uncompensated spins are dominantly
+frozen with nearly no rotating spins due to the chemical intermixing, which
+correlates to the inferred mechanism for the exchange bias.",0912.1734v1
+2009-12-16,Large anisotropy of spin-orbit interaction in a single InAs self-assembled quantum dot,"Anisotropy of spin-orbit interaction (SOI) is studied for a single uncapped
+InAs self-assembled quantum dot (SAQD) holding just a few electrons. The SOI
+energy is evaluated from anti-crossing or SOI induced hybridization between the
+ground and excited states with opposite spins. The magnetic angular dependence
+of the SOI energy falls on an absolute cosine function for azimuthal rotation,
+and a cosine-like function for tilting rotation. The SOI energy is even
+quenched at a specific rotation. These angular dependence compare well to
+calculation of Rashba SOI in a two-dimensional harmonic potential.",0912.3088v1
+2010-01-11,Multiscale autocorrelation function: a new approach to anisotropy studies,"We present a novel catalog-independent method, based on a scale dependent
+approach, to detect anisotropy signatures in the arrival direction distribution
+of the ultra highest energy cosmic rays (UHECR). The method provides a good
+discrimination power for both large and small data sets, even in presence of
+strong contaminating isotropic background. We present some applications to
+simulated data sets of events corresponding to plausible scenarios for charged
+particles detected by world-wide surface detector-based observatories, in the
+last decades.",1001.1666v4
+2010-01-13,Rotation of elliptic optical beam in anisotropic media,"We investigate the linear propagation of a paraxial optical beam in
+anisotropic media. We start from the eigenmode solution of the plane wave in
+the media, then subsequently derive the wave equation for the beam propagating
+along a general direction except the optic axes. The wave equation has a term
+containing the second mixed partial derivative which originates from the
+anisotropy, and this term can result in the rotation of the beam spot. The
+rotation effect is investigated by solving analytically the wave equation with
+an initial elliptical Gaussian beam for both uniaxial and biaxial media. For
+both media, it is found that there exists a specific direction, which is
+dependent on anisotropy of the media, on the cross-section perpendicular to
+propagation direction to determine the rotation of the beam spot. When the
+major axis of the elliptical spot of the input beam is parallel to or
+perpendicular to the specific direction, the beam spot will not rotate during
+propagation, otherwise, it will rotate with the direction and the velocity
+determined by input parameters of the beam.",1001.2061v2
+2010-01-18,On the stability of the shear-free condition,"The evolution equation for the shear is reobtained for a spherically
+symmetric anisotropic, viscous dissipative fluid distribution, which allows us
+to investigate conditions for the stability of the shear-free condition. The
+specific case of geodesic fluids is considered in detail, showing that the
+shear-free condition, in this particular case, may be unstable, the departure
+from the shear-free condition being controlled by the expansion scalar and a
+single scalar function defined in terms of the anisotropy of the pressure, the
+shear viscosity and the Weyl tensor or, alternatively, in terms of the
+anisotropy of the pressure, the dissipative variables and the energy density
+inhomogeneity.",1001.3020v1
+2010-01-26,Observational Limits on Patchy Reionization: Implications for B-modes,"The recent detection of secondary CMB anisotropy by the South Pole Telescope
+places a conservative bound on temperature fluctuations from the optical
+depth-modulated Doppler effect of T_{3000} < sqrt{13} microK at multipoles
+l~3000. This bound is the first empirical constraint on reionization optical
+depth fluctuations at arcminute scales, tau_{3000} = 0.001 T_{3000}/microK,
+implying that these fluctuations are no more than a few percent of the mean.
+Optical depth modulation of the quadrupole source to polarization generates
+B-modes that are correspondingly bounded as B_{3000} = 0.003 T_{3000}. The
+maximal extrapolation to the l~100 gravitational wave regime yields B_{100} =
+0.1 T_{3000} and remains in excess of gravitational lensing if the effective
+comoving size of the ionizing regions is R > 80 Mpc. If patchy reionization is
+responsible for much of the observed arcminute scale temperature fluctuations,
+current bounds on B_{100} already require R < 200 Mpc and can be expected to
+improve rapidly. Frequency separation of thermal Sunyaev-Zel'dovich
+contributions to the measured secondary anisotropy would also substantially
+improve the limits on optical depth fluctuations and B-modes from reionization.",1001.4803v1
+2010-02-01,Vortex state in d-wave superconductors with strong paramagnetism: transport and specific heat anisotropy,"We analyse the combined effect of orbital and Pauli depairing on the
+superconducting state, and apply the results to the heavy fermion CeCoIn$_5$.
+We find that: a) standard extrapolation based on the slope of $H_{c2}(T)$ in
+the vicinity of the transition temperature to T=0 does not always give accurate
+values of the orbital upper critical field; b) critical value of the Maki
+parameter, $\alpha$, that determines onset of the first order transition
+depends on the Fermi surface shape and the symmetry of the gap, and is
+$\alpha^*\approx 3$ for CeCoIn$_5$; c) the anisotropy of the thermodynamic and
+transport coefficients in the low-temperature, low-field part of the phase
+diagram is essentially insensitive to the Zeeman field and can be used to
+determine the nodal directions in Pauli-limited superconductors. The latter
+result confirms the finding of the $d_{x^2-y^2}$ order parameter CeCoIn$_5$.",1002.0330v1
+2010-02-12,Anisotropy of Solar Wind Turbulence between Ion and Electron Scales,"The anisotropy of turbulence in the fast solar wind, between the ion and
+electron gyroscales, is directly observed using a multispacecraft analysis
+technique. Second order structure functions are calculated at different angles
+to the local magnetic field, for magnetic fluctuations both perpendicular and
+parallel to the mean field. In both components, the structure function value at
+large angles to the field S_perp is greater than at small angles S_par: in the
+perpendicular component S_perp/S_par = 5 +- 1 and in the parallel component
+S_perp/S_par > 3, implying spatially anisotropic fluctuations, k_perp > k_par.
+The spectral index of the perpendicular component is -2.6 at large angles and
+-3 at small angles, in broad agreement with critically balanced whistler and
+kinetic Alfven wave predictions. For the parallel component, however, it is
+shallower than -1.9, which is considerably less steep than predicted for a
+kinetic Alfven wave cascade.",1002.2539v2
+2010-02-19,Confinement-Induced Resonances in Low-Dimensional Quantum Systems,"We report on the observation of confinement-induced resonances in strongly
+interacting quantum-gas systems with tunable interactions for one- and
+two-dimensional geometry. Atom-atom scattering is substantially modified when
+the s-wave scattering length approaches the length scale associated with the
+tight transversal confinement, leading to characteristic loss and heating
+signatures. Upon introducing an anisotropy for the transversal confinement we
+observe a splitting of the confinement-induced resonance. With increasing
+anisotropy additional resonances appear. In the limit of a two-dimensional
+system we find that one resonance persists.",1002.3795v2
+2010-02-19,Highly sensitive frequency metrology for optical anisotropy measurements,"In this paper we present a novel apparatus aimed at measuring very small
+birefringences and anisotropies, based on frequency metrology and not on
+polarimetry as usual. In our experiment, a very high finesse resonant cavity is
+used to convert the phase difference into a resonance frequency difference,
+which can then be measured with very high accuracy. We describe the set-up and
+present the results of experimental tests which exhibited a sensitivity dn ~ 2
+x 10?18, allowing for the measurement of long-predicted magneto-electro-optical
+effects in gases. Since the shotnoise limited sensitivity of our apparatus lies
+well below the state-of-the-art sensitivity, frequency metrology appears as a
+promising technique for small birefringence measurements.",1002.3812v1
+2010-02-24,The entanglement dynamics of interacting qubits embedded in a spin environment with Dzyaloshinsky-Moriya term,"We investigate the entanglement dynamics of two interacting qubits in a spin
+environment, which is described by an XY model with Dzyaloshinsky-Moriya (DM)
+interaction. The competing effects of environmental noise and interqubit
+coupling on entanglement generation for various system parameters are studied.
+We find that the entanglement generation is suppressed remarkably in
+weak-coupling region at quantum critical point (QCP). However, the suppression
+of the entanglement generation at QCP can be compensated both by increasing the
+DM interaction and by decreasing the anisotropy of the spin chain. Beyond the
+weak-coupling region, there exist resonance peaks of concurrence when the
+system-bath coupling equals to external magnetic field. We attribute the
+presence of resonance peaks to the flat band of the self-Hamiltonian. These
+peaks are highly sensitive to anisotropy parameter and DM interaction.",1002.4476v3
+2010-02-26,Constraints on the SZ Power Spectrum on Degree Angular Scales in WMAP Data,"The Sunyaev-Zel'dovich (SZ) effect has a distinct spectral signature that
+allows its separation from fluctuations in the cosmic microwave background
+(CMB) and foregrounds. Using CMB anisotropies measured in Wilkinson Microwave
+Anisotropy Probe's five-year maps, we constrain the SZ fluctuations at large,
+degree angular scales corresponding to multipoles in the range from 10 to 400.
+We provide upper bounds on SZ fluctuations at multipoles greater than 50, and
+find evidence for a hemispherically asymmetric signal at ten degrees angular
+scales. The amplitude of the detected signal cannot be easily explained with
+the allowed number density and temperature of electrons in the Galactic halo.
+We have failed to explain the excess signal as a residual from known Galactic
+foregrounds or instrumental uncertainties such as 1/f-noise.",1002.4872v4
+2010-03-02,Observable effects of anisotropic bubble nucleation,"Our universe may have formed via bubble nucleation in an eternally-inflating
+background. Furthermore, the background may have a compact dimension--the
+modulus of which tunnels out of a metastable minimum during bubble
+nucleation--which subsequently grows to become one of our three large spatial
+dimensions. Then the reduced symmetry of the background is equivalent to
+anisotropic initial conditions in our bubble universe. We compute the
+inflationary spectrum in such a scenario and, as a first step toward
+understanding the effects of anisotropy, project it onto spherical harmonics.
+The resulting spectrum exhibits anomalous multipole correlations, their
+relative amplitude set by the present curvature parameter, which extend to
+arbitrarily large multipole moments. This raises the possibility of future
+detection, if slow-roll inflation does not last too long within our bubble. A
+full understanding of the observational signal must account for the effects of
+background anisotropy on photon free streaming, and is left to future work.",1003.0663v2
+2010-03-04,Comparative study of transport and magnetic Jc in the polycrystalline iron-based superconductor NdFeAsO{0.88}F{0.12},"Polycrystalline NdFeAsO0.88F0.12 superconductors prepared by high pressure
+(HP) and ambient pressure (AP) method were comparatively studied by
+magnetization and transport measurements. Upper critical field (Hc2),
+irreversibility field (Hirr) and the anisotropy parameter were estimated from
+resistance transition curves. The broadening of transition width was observed,
+and ascribed to both Hc2 anisotropy and superconductivity inhomogeneity of
+samples. Magnetic hysteresis loops (MHLs) in low fields were measured to detect
+the trace of weak-link behavior. The reclosed hysteresis loops in low fields
+manifest that there are weak-links in both samples. Magnetization critical
+current density Jcm were derived from MHLs. High-pressure synthesized sample
+shows higher Jcm. However, by means of direct transport I-V measurements,
+transport critical current density Jct was very low. The Jct values for two
+samples are comparable. Large discrepancies between Jcm and Jct also indicate
+that there are weak-links in both samples. The relative mechanism is discussed
+in detail.",1003.0946v2
+2010-03-05,Weak superconducting fluctuations and small anisotropy of the upper critical fields in an Fe1.05Te0.85Se0.15 single crystal,"We have investigated the temperature dependence of the resistive upper
+critical fields ($\mu_{0}H_{\rm c2}(T)$) for an
+Fe$_{1.05}$Te$_{0.85}$Se$_{0.15}$ single crystal, which exhibit
+superconductivity at $T_{\rm c} \sim 14 K, in magnetic fields of up to 55 T.
+Two-dimensional feature and superconducting fluctuations of the samples are
+found to be weak, because the resistive broadening effect on applied magnetic
+fields of up to 14 T is small. The Pauli paramagnetic effect is obviously
+evidenced by the strong suppression of the $\mu_{0}H_{\rm c2}^{ab}(T)$ ($H
+\parallel ab$) curve and nearly isotropic $\mu_{0}H_{\rm c2}(0) \approx 47 T is
+seen for both $H \parallel ab$ and $H \parallel c$. This fact is almost
+identical to the results of Fe$_{1+y}$Te$_{0.6}$Se$_{0.4}$ single crystals
+reported previously. We have discussed that the small anisotropy of the upper
+critical field at low temperatures in Fe$_{1+y}$(Te,Se) systems against the
+variation of the Te/Se ratio.",1003.1171v3
+2010-03-08,Anisotropic and quasipropagating spin excitations in superconducting Ba(Fe0.926Co0.074)2As2,"Inelastic neutron scattering from superconducting (SC)
+Ba(Fe$_{0.926}$Co$_{0.074}$)$_2$As$_2$ reveals anisotropic and
+quasi-two-dimensional (2D) magnetic excitations close to
+\textbf{Q}$_{\texttt{AFM}}=({1}{2}/{1}{2})$ - the 2D antiferromagnetic (AFM)
+wave-vector of the parent BaFe$_2$As$_2$ compound. The correlation length
+anisotropy of these low energy fluctuations is consistent with spin nematic
+correlations in the $J_1$-$J_2$ model with $J_1/J_2 \sim$ 1. The spin resonance
+at $\sim$8.3 meV in the SC state displays the same anisotropy. The anisotropic
+fluctuations experimentally evolve into two distinct maxima only along the
+direction transverse to \textbf{Q}$_{\texttt{AFM}}$ above $\sim$80 meV
+indicating unusual quasi-propagating excitations.",1003.1687v4
+2010-03-09,Shear Viscosity in the Post-quasistatic Approximation,"We apply the post-quasi--static approximation, an iterative method for the
+evolution of self-gravitating spheres of matter, to study the evolution of
+anisotropic non-adiabatic radiating and dissipative distributions in General
+Relativity. Dissipation is described by viscosity and free-streaming radiation,
+assuming an equation of state to model anisotropy induced by the shear
+viscosity. We match the interior solution, in non-comoving coordinates, with
+the Vaidya exterior solution. Two simple models are presented, based on the
+Schwarzschild and Tolman VI solutions, in the non--adiabatic and adiabatic
+limit. In both cases the eventual collapse or expansion of the distribution is
+mainly controlled by the anisotropy induced by the viscosity.",1003.1825v3
+2010-03-10,Effects of excess Fe on upper critical field and magnetotransport in Fe1+y(Te1-xSx)z,"We have investigated the upper critical field anisotropy and magnetotransport
+properties of Fe1.14(1)Te0.91(2)S0.09(2) single crystals in stable magnetic
+fields up to 35 T. The results show that u0Hc2(T) along the c axis and in the
+ab-plane exhibit saturation at low temperatures. The anisotropy of u0Hc2(T)
+decreases with decreasing temperature, becoming nearly isotropic for T->0. Our
+analysis indicates that the spin-paramagnetic pair-breaking with spin-orbital
+scattering is responsible for the behavior of u0Hc2(T). Furthermore, from
+analysis of the normal state properties, we show evidence that the excess Fe
+acting as Kondo-type impurities is a key factor determining the normal and
+superconducting state physical properties.",1003.2209v1
+2010-03-11,Structural and Magnetic Properties of Nanosized Barium Hexaferrite Powders Obtained by Microemulsion Technique,"Thin hexagonal barium hexaferrite particles synthesized using the
+microemulsion technique were studied. A water-in-oil reverse microemulsion
+system with cetyltrimethylammonium bromide (CTAB) as a cationic surfactant,
+n-butanol as a co-surfactant, n-hexanol as a continuous oil phase, and an
+aqueous phase were used. The microstructural and magnetic properties were
+investigated. The particles obtained were mono-domain with average particle
+size 280 nm. The magnetic properties of the powder were investigated at 4.2 K
+and at room temperature. The saturation magnetization was 48.86 emu/g and the
+coercivity, 2.4 x 105 A/m at room temperature. The anisotropy field Ha and
+magneto-crystalline anisotropy K1 were 1.4 x 106 A/m and 2.37 x 105 J/m3,
+respectively.",1003.2276v1
+2010-03-12,Tunable striped-patterns by lattice anisotropy and magnetic impurities in d-wave superconductors,"The pattern transition induced by lattice anisotropy (LA) and magnetic
+impurities is computationally observed in near-optimally doped d-wave
+superconductors (DSCs). For the single impurity case, a transition from the
+checkerboard to stripe pattern can be induced even with a very weak LA.
+Moreover, the modulation period of eight lattice constants (8$a$) in the spin
+order coincides with neutron scattering data. For the two-impurity case, an
+orientation transition from the longitudinal impurity-pinned stripe into the
+transverse pattern is observed when the LA ratio reaches some critical value.
+At the critical point, it is found that the structures around magnetic
+impurities could restore checkerboard patterns. These results indicate that the
+formation of stripes in DSCs might induced by various effects, and could be
+tunable experimentally.",1003.3023v2
+2010-03-23,Growth and Anisotropic Properties of RBa_2Cu_3O_x Single-Crystal Whiskers,"Single-crystal whiskers of RBa2Cu3Ox (R-123, R = Sm, Eu, Gd, Dy, Ho, Er, Tm,
+Yb, and Y) were successfully grown from Sb- or Te-doped precursors with a
+nominal composition of R1.5Ba2.75-3.00Cu3M0.5Ox (M: Sb,Te). The whiskers were
+grown parallel to the ab-plane with the following typical dimensions: 2-8 mm in
+length, 20-80 \mum in width, and 10-30 \mum in thickness. In the case of
+rare-earth ions (R3+) with a small ionic radius (Dy, Ho, Er, Tm, Yb, and Y),
+R-123 whiskers were grown from Te-doped precursors. The growths of Y-123 and
+Ho-123 whiskers were confirmed using both Te-doped and Sb-doped precursors. On
+the other hand, for rare-earth ions (R3+) with a large ionic radius (Sm, Eu,
+and Gd), R-123 whiskers were grown only from Sb-doped precursors. Sb and Te
+were not detected in the grown whiskers by electron probe microanalysis. The
+anisotropies of R-123 single-crystal whiskers in the flux liquid state were
+estimated to be 6.0-33 from the angular dependence of their resistivities under
+various magnetic fields. The anisotropy increased with decreasing
+superconducting transition temperature.",1003.4371v1
+2010-03-24,Structural and magnetic evidence of confined strain fields in GaMnAs grown on ordered arrays of zero-dimensional nanostructures,"We prepared Ga0.95Mn0.05As films on top of periodic arrays of InAs quantum
+dots. X-ray diffraction reveals periodically strained films, commensurate to
+substrate's patterning. The dots produce a tensile strain in GaMnAs while
+between the dots strain is compressive. Our experiments confirm that the
+average tensile strain in the film increases with decreasing dots separation.
+This trend in strain is accompanied by an increase of the out-of-plane
+magnetization component familiar from the established relation between strain
+and magnetic anisotropy in GaMnAs films. Our work provides a new route for
+controlling magneto-crystalline anisotropies in GaMnAs on a nanometer scale.",1003.4768v1
+2010-04-02,Anisotropic 2D diffusive expansion of ultra-cold atoms in a disordered potential,"We study the horizontal expansion of vertically confined ultra-cold atoms in
+the presence of disorder. Vertical confinement allows us to realize a situation
+with a few coupled harmonic oscillator quantum states. The disordered potential
+is created by an optical speckle at an angle of 30{\deg} with respect to the
+horizontal plane, resulting in an effective anisotropy of the correlation
+lengths of a factor of 2 in that plane. We observe diffusion leading to
+non-Gaussian density profiles. Diffusion coefficients, extracted from the
+experimental results, show anisotropy and strong energy dependence, in
+agreement with numerical calculations.",1004.0312v1
+2010-04-05,Neutrino and axion hot dark matter bounds after WMAP-7,"We update cosmological hot dark matter constraints on neutrinos and hadronic
+axions. Our most restrictive limits use 7-year data from the Wilkinson
+Microwave Anisotropy Probe for the cosmic microwave background anisotropies,
+the halo power spectrum (HPS) from the 7th data release of the Sloan Digital
+Sky Survey, and the Hubble constant from Hubble Space Telescope observations.
+We find 95% C.L. upper limits of \sum m_\nu<0.44 eV (no axions), m_a<0.91 eV
+(assuming \sum m_\nu=0), and \sum m_\nu<0.41 eV and m_a<0.72 eV for two hot
+dark matter components after marginalising over the respective other mass. CMB
+data alone yield \sum m_\nu<1.19 eV (no axions), while for axions the HPS is
+crucial for deriving m_a constraints. This difference can be traced to the fact
+that for a given hot dark matter fraction axions are much more massive than
+neutrinos.",1004.0695v2
+2010-04-09,Perpendicular anisotropy of ultrathin epitaxial cobalt films on graphene,"Graphene is attractive for spintronics due to its long spin life time and
+high mobility. So far only thick and polycrystalline slabs have been used as
+ferromagnetic electrodes. We report the growth of flat, epitaxial ultrathin Co
+films on graphene. These display perpendicular magnetic anisotropy in the
+thickness range 0.5-1nm, which is confirmed by theory. PMA, epitaxy and
+ultrathin thickness bring new perspectives for graphene-based spintronic
+devices such as the zero-field control of an arbitrary magnetization direction,
+band matching between electrodes and graphene, and interface effects such as
+Rashba and electric field control of magnetism.",1004.1463v1
+2010-04-16,Collective Diffusion of Colloidal Hard Rods in Smectic Liquid Crystals: Effect of Particle Anisotropy,"We study the layer-to-layer diffusion in smectic-A liquid crystals of
+colloidal hard rods with different length-to-diameter ratios using computer
+simulations. The layered arrangement of the smectic phase yields a hopping-type
+diffusion due to the presence of permanent barriers and transient cages.
+Remarkably, we detect stringlike clusters composed of inter-layer rods moving
+cooperatively along the nematic director. Furthermore, we find that the
+structural relaxation in equilibrium smectic phases shows interesting
+similarities with that of out-of-equilibrium supercooled liquids, although
+there the particles are kinetically trapped in transient rather than permanent
+cages. Additionally, at fixed packing fraction we find that the barrier height
+increases with increasing particle anisotropy, and hence the dynamics is more
+heterogeneous and non-Gaussian for longer rods, yielding a lower diffusion
+coefficient along the nematic director and smaller clusters of inter-layer
+particles that move less cooperatively. At fixed barrier height, the dynamics
+becomes more non-Gaussian and heterogeneous for longer rods that move more
+collectively giving rise to a higher diffusion coefficient along the nematic
+director.",1004.2897v1
+2010-04-21,Missing Power vs low-l Alignments in the Cosmic Microwave Background: No Correlation in the Standard Cosmological Model,"On large angular scales (greater than about 60 degrees), the two-point
+angular correlation function of the temperature of the cosmic microwave
+background (CMB), as measured (outside of the plane of the Galaxy) by the
+Wilkinson Microwave Anisotropy Probe, shows significantly lower large-angle
+correlations than expected from the standard inflationary cosmological model.
+Furthermore, when derived from the full CMB sky, the two lowest cosmologically
+interesting multipoles, the quadrupole (l=2) and the octopole (l=3), are
+unexpectedly aligned with each other. Using randomly generated full-sky and
+cut-sky maps, we investigate whether these anomalies are correlated at a
+statistically significant level. We conclusively demonstrate that, assuming
+Gaussian random and statistically isotropic CMB anisotropies, there is no
+statistically significant correlation between the missing power on large
+angular scales in the CMB and the alignment of the l=2 and l=3 multipoles. The
+chance to measure the sky with both such a lack of large-angle correlation and
+such an alignment of the low multipoles is thus quantified to be below 10^{-6}.",1004.3784v1
+2010-04-22,"Superconducting order parameter in nonmagnetic borocarbides RNi$_{2}$B$_{2}$C (R=Y, Lu) probed by point-contact Andreev reflection spectroscopy","We report on the measurements of the superconducting order parameter in the
+nonmagnetic borocarbides LuNi$_2$B$_2$C and YNi$_2$B$_2$C. Andreev conductance
+spectra are obtained from nanoscale metallic junctions on single crystal
+surfaces prepared along three major crystallographic orientations: [001],
+[110], and [100]. The gap values extracted by the single-gap
+Blonder-Tinkham-Klapwijk model follow the BCS predictions as a function of
+temperature and magnetic field and exhibit a small anisotropy. These
+observations are robust and reproducible among all the measurements on two
+different sets of LuNi$_2$B$_2$C crystals and one set of YNi$_2$B$_2$C
+crystals. We suggest possible explanations for the small gap anisotropy based
+on the recent detailed gap measurements by angle-resolved photoemission
+spectroscopy and the tunneling cone effect. Our results provide a consistent
+picture of the superconducting gap structure in these materials, addressing the
+controversy particularly in the reported results of point-contact Andreev
+reflection spectroscopy.",1004.3846v1
+2010-04-26,Orbital Order and Spontaneous Orthorhombicity in Iron Pnictides,"A growing list of experiments show orthorhombic electronic anisotropy in the
+iron pnictides, in some cases at temperatures well above the spin density wave
+transition. These experiments include neutron scattering, resistivity and
+magnetoresistance measurements, and a variety of spectroscopies. We explore the
+idea that these anisotropies stem from a common underlying cause: orbital order
+manifest in an unequal occupation of $d_{xz}$ and $d_{yz}$ orbitals, arising
+from the coupled spin-orbital degrees of freedom. We emphasize the distinction
+between the total orbital occupation (the integrated density of states), where
+the order parameter may be small, and the orbital polarization near the Fermi
+level which can be more pronounced. We also discuss light-polarization studies
+of angle-resolved photoemission, and demonstrate how x-ray absorption linear
+dichroism may be used as a method to detect an orbital order parameter.",1004.4611v2
+2010-04-27,Anisotropic Pressures at Ultra-stiff Singularities and the Stability of Cyclic Universes,"We show that the inclusion of simple anisotropic pressures stops the
+isotropic Friedmann universe being a stable attractor as an initial or final
+singularity is approached when pressures can exceed the energy density. This
+shows that the situation with isotropic pressures, studied earlier in the
+context of cyclic and ekpyrotic cosmologies, is not generic, and Kasner-like
+behaviour occurs when simple pressure anisotropies are present. We find all the
+asymptotic behaviours and determine the dynamics when the anisotropic principal
+pressures are proportional to the density. We expect distortions and
+anisotropies to be significantly amplified through a simple cosmological bounce
+in cyclic or ekpyrotic cosmologies when ultra-stiff pressures are present.",1004.4767v1
+2010-04-30,Large-angle anomalies in the CMB,"We review the recently found large-scale anomalies in the maps of temperature
+anisotropies in the cosmic microwave background. These include alignments of
+the largest modes of CMB anisotropy with each other and with geometry and
+direction of motion of the Solar System, and the unusually low power at these
+largest scales. We discuss these findings in relation to expectation from
+standard inflationary cosmology, their statistical significance, the tools to
+study them, and the various attempts to explain them.",1004.5602v2
+2010-05-02,CMB Constraints on a Stochastic Background of Primordial Magnetic Fields,"We constrain a stochastic background of primordial magnetic field (PMF) by
+its contribution to the angular power spectrum of cosmic microwave background
+anisotropies. We parametrize such stochastic background by a power-law spectrum
+with index $n_B$ and by its Gaussian smoothed amplitude $B_\lambda$ on a
+comoving length $\lambda$. We give an approximation for the spectra of the
+relevant correlators of the energy-momentum of the stochastic background of PMF
+for any $n_B$. By using the WMAP 7 year data in combination with ACBAR, BICEP
+and QUAD we obtain the constraint $B_{1 {\rm Mpc}} < 5.0$ nG at 95% confidence
+level for a stochastic background of non-helical PMF. We discuss the relative
+importance of the scalar and vector contribution to CMB anisotropies in
+obtaining these constraints. We then forecast {\sc Planck} capabilities in
+constraining $B_{1 {\rm Mpc}}$.",1005.0148v2
+2010-05-03,Collective spin mode in a multi-component system of coupled itinerant and localized electrons,"We study collective spin excitations of a magnetically ordered state in a
+multi-component system composed of both itinerant electrons and local moments.
+Here the induced spin-density-wave (SDW) ordering of itinerant electrons and
+the collinear antiferromangetic (AF) ordering of local moments are locked
+together via a Hund's rule coupling. We show that the Goldstone theorem still
+holds at the RPA level with the gapless spin wave protected inside the small
+SDW gap of itinerant electrons, which, however, is fragile in the presence of
+ion-anisotropy. A gapped out-of-phase spin mode extending over a much wider
+energy scale above the SDW gap is found to be more robust against the
+ion-anisotropy, which is mainly contributed by the local moment fluctuations.
+While the scattering between the Goldstone mode and itinerant electrons
+diminishes within the SDW gap, the out-of-phase mode will strongly interact
+with itinerant electrons and thus dominate the spin and charge dynamics in such
+an ordered phase. Possible relevance of such a model to the iron-pnictides will
+be also discussed.",1005.0421v1
+2010-05-05,Structure-Sensitive Mechanism of Nanographene Failure,"The response of a nanographene sheet to external stresses is considered in
+terms of a mechanochemical reaction. The quantum chemical realization of the
+approach is based on a coordinate-of-reaction concept for the purpose of
+introducing a mechanochemical internal coordinate (MIC) that specifies a
+deformational mode. The related force of response is calculated as the energy
+gradient along the MIC, while the atomic configuration is optimized over all of
+the other coordinates under the MIC constant-pitch elongation. The approach is
+applied to the benzene molecule and (5, 5) nanographene. A drastic anisotropy
+in the microscopic behavior of both objects under elongation along a MIC has
+been observed when the MIC is oriented either along or normally to the C-C
+bonds chain. Both the anisotropy and high stiffness of the nanographene
+originate at the response of the benzenoid unit to stress.",1005.0796v1
+2010-05-05,Lensing reconstruction of cluster-mass cross-correlation with cosmic microwave background polarization,"We extend our maximum likelihood method for reconstructing the cluster-mass
+cross-correlation from cosmic microwave background (CMB) temperature
+anisotropies and develop new estimators that utilize six different quadratic
+combinations of CMB temperature and polarization fields. Our maximum likelihood
+estimators are constructed with delensed CMB temperature and polarization
+fields by using an assumed model of the convergence field and they can be
+iteratively applied to a set of clusters, approaching to the optimal condition
+for the lensing reconstruction as the assumed initial model is refined. Using
+smoothed particle hydrodynamics simulations, we create a catalog of realistic
+clusters obtainable from the current Sunyaev-Zel'dovich (SZ) surveys, and we
+demonstrate the ability of the maximum likelihood estimators to reconstruct the
+cluster-mass cross-correlation from the massive clusters. The iTT temperature
+estimator provides a signal-to-noise ratio of a factor 3 larger than the iEB
+polarization estimator, unless the detector noise for measuring polarization
+anisotropies is controlled under 3 microK.",1005.0847v2
+2010-05-06,Anisotropic excitonic effects in the energy loss function of hexagonal boron nitride,"We demonstrate that the valence energy-loss function of hexagonal boron
+nitride (hBN) displays a strong anisotropy in shape, excitation energy and
+dispersion for momentum transfer q parallel or perpendicular to the hBN layers.
+This is manifested by e.g. an energy shift of 0.7 eV that cannot be captured by
+single-particle approaches and is a demonstration of a strong anisotropy in the
+two-body electron-hole interaction. Furthermore, for in-plane directions of q
+we observe a splitting of the -plasmon in the M direction that is absent in the
+K direction and this can be traced back to band-structure effects.",1005.0930v1
+2010-05-10,An attractor for dark matter structures,"Cosmological simulations of dark matter structures have identified a set of
+universal profiles, and similar characteristics have been seen in
+non-cosmological simulations. It has therefore been speculated whether these
+profiles of collisionless systems relate to accretion and merger history, or if
+there is an attractor for the dark matter systems. Here we identify such a
+1-dimensional attractor in the 3-dimensional space spanned by the 2 radial
+slopes of the density and velocity dispersion, and the velocity anisotropy.
+This attractor effectively removes one degree of freedom from the Jeans
+equation. It also allows us to speculate on a new fluid interpretation for the
+Jeans equation, with an effective polytropic index for the dark matter
+particles between 1/2 and 3/4. If this attractor solution holds for other
+collisionless structures, then it may hold the key to break the mass-anisotropy
+degeneracy, which presently prevents us from measuring the mass profiles in
+dwarf galaxies uniquely.",1005.1643v1
+2010-05-11,Magnetization vector in the reversible region of a highly anisotropic cuprate superconductor: anisotropy factor and the role of 2D vortex fluctuations,"By using a high quality Tl2Ba2Ca2Cu3O10 (Tl-2223) single crystal as an
+example, the magnetization vector was probed in the reversible region of highly
+anisotropic cuprate superconductors. For that, we have measured its components
+along and transverse to the applied magnetic field for different crystal
+orientations. The analysis shows that the angular dependence of the
+perpendicular component of the magnetization vector follows the one predicted
+by a London-like approach which includes a contribution associated with the
+thermal fluctuations of the 2D vortex positions. For the Tl-2223 crystal
+studied here, a lower bound for the anisotropy factor was estimated to be about
+190.",1005.1777v1
+2010-05-13,Pseudo-Dipole Signal Removal from WMAP Data,"It is discovered in our previous work that different observational
+systematics, e.g., errors of antenna pointing directions, asynchronous between
+the attitude and science data, can generate pseudo-dipole signal in full-sky
+maps of the cosmic microwave background (CMB) anisotropy published by The
+Wilkinson Microwave Anisotropy Probe (WMAP) team. Now the antenna sidelobe
+response to the Doppler signal is found to be able to produce similar effect as
+well. In this work, independent to the sources, we uniformly model the
+pseudo-dipole signal and remove it from published WMAP7 CMB maps by model
+fitting. The result demonstrates that most of the released WMAP CMB quadrupole
+is artificial.",1005.2352v3
+2010-05-18,Nematic liquid crystal dynamics under applied electric fields,"In this paper we investigate the dynamics of liquid crystal textures in a
+two-dimensional nematic under applied electric fields, using numerical
+simulations performed using a publicly available LIquid CRystal Algorithm
+(LICRA) developed by the authors. We consider both positive and negative
+dielectric anisotropies and two different possibilities for the orientation of
+the electric field (parallel and perpendicular to the two-dimensional lattice).
+We determine the effect of an applied electric field pulse on the evolution of
+the characteristic length scale and other properties of the liquid crystal
+texture network. In particular, we show that different types of defects are
+produced after the electric field is switched on, depending on the orientation
+of the electric field and the sign of the dielectric anisotropy.",1005.3083v1
+2010-05-18,Determining Magnetic Nanoparticle Size Distributions from Thermomagnetic Measurements,"Thermomagnetic measurements are used to obtain the size distribution and
+anisotropy of magnetic nanoparticles. An analytical transformation method is
+described which utilizes temperature-dependent zero-field cooling (ZFC)
+magnetization data to provide a quantitative measurement of the average
+diameter and relative abundance of superparamagnetic nanoparticles. Applying
+this method to self-assembled MnAs nanoparticles in MnAs-GaAs composite films
+reveals a log-normal size distribution and reduced anisotropy for nanoparticles
+compared to bulk materials. This analytical technique holds promise for rapid
+assessment of the size distribution of an ensemble of superparamagnetic
+nanoparticles.",1005.3252v2
+2010-05-26,Cosmic strings and their induced non-Gaussianities in the cosmic microwave background,"Motivated by the fact that cosmological perturbations of inflationary quantum
+origin were born Gaussian, the search for non-Gaussianities in the cosmic
+microwave background (CMB) anisotropies is considered as the privileged probe
+of non-linear physics in the early universe. Cosmic strings are active sources
+of gravitational perturbations and incessantly produce non-Gaussian distortions
+in the CMB. Even if, on the currently observed angular scales, they can only
+contribute a small fraction of the CMB angular power spectrum, cosmic strings
+could actually be the main source of its non-Gaussianities. In this article,
+after having reviewed the basic cosmological properties of a string network, we
+present the signatures Nambu-Goto cosmic strings would induce in various
+observables ranging from the one-point function of the temperature anisotropies
+to the bispectrum and trispectrum. It is shown that string imprints are
+significantly different than those expected from the primordial type of
+non-Gaussianity and could therefore be easily distinguished.",1005.4842v2
+2010-06-07,"Theory of spin waves in ferromagnetic (Ga,Mn)As","The collective behavior of spins in a dilute magnetic semiconductor is
+determined by their mutual interactions and influenced by the underlying
+crystal structure. Hence, we begin with the atomic quantum-mechanical
+description of this system using the proposed variational-perturbation
+calculus, and then turn to the emerging macroscopic picture employing
+phenomenological constants. Within this framework we study spin waves and
+exchange stiffness in the p-d Zener model of (Ga,Mn)As, its thin layers and
+bulk crystals described by the spds* tight-binding approximation. Analyzing the
+anisotropic part of exchange, we find that the Dzyaloshinskii-Moriya
+interaction may lead to the cycloidal spin arrangement and uniaxial in-plane
+anisotropy in thin layers, resulting in a surface-like anisotropy in thicker
+films. We also derive and discuss the spin-wave contribution to magnetization
+and Curie temperature. Our theory reconstructs the values of stiffness
+determined from the temperature dependence of magnetization, but reproduces
+only partly those obtained from analyzing precession modes in (Ga,Mn)As thin
+films.",1006.1271v4
+2010-06-09,Electric Control of Multiple Domain Walls in Pt/Co/Pt Nanotrack with Perpendicular Magnetic Anisotropy,"Electric control of multiple domain walls (DWs) motion is demonstrated by
+Pt/Co/Pt nanotracks with perpendicular magnetic anisotropy. Due to the weak
+microstructural disorders with small DW propagation field, the purely
+current-driven DW motion is achieved in the creep regime at current densities
+less than 10^7 A/cm^2 at room temperature. It is confirmed that by use of a
+scanning magneto-optical Kerr effect microscope, several DWs are simultaneously
+and identically displaced by the same distance in the same direction. Utilizing
+such DWs motion, we succeed to realize random bits writing and transferring as
+a device prototype of four-bit shift registers.",1006.1726v1
+2010-06-15,PIC Simulations of the Temperature Anisotropy-Driven Weibel Instability: Analyzing the perpendicular mode,"An instability driven by the thermal anisotropy of a single electron species
+is investigated in a 2D particle-in-cell (PIC) simulation. This instability is
+the one considered by Weibel and it differs from the beam driven filamentation
+instability. A comparison of the simulation results with analytic theory
+provides similar exponential growth rates of the magnetic field during the
+linear growth phase of the instability. We observe in accordance with previous
+works the growth of electric fields during the saturation phase of the
+instability. Some components of this electric field are not accounted for by
+the linearized theory. A single-fluid-based theory is used to determine the
+source of this nonlinear electric field. It is demonstrated that the magnetic
+stress tensor, which vanishes in a 1D geometry, is more important in this
+2-dimensional model used here. The electric field grows to an amplitude, which
+yields a force on the electrons that is comparable to the magnetic one. The
+peak energy density of each magnetic field component in the simulation plane
+agrees with previous estimates. Eddy currents develop, which let the amplitude
+of the third magnetic field component grow, which is not observed in a 1D
+simulation.",1006.3057v1
+2010-06-16,Phase transformation in Si from semiconducting diamond to metallic beta-Sn phase in QMC and DFT under hydrostatic and anisotropic stress,"Silicon undergoes a phase transition from the semiconducting diamond phase to
+the metallic beta-Sn phase under pressure. We use quantum Monte Carlo
+calculations to predict the transformation pressure and compare the results to
+density functional calculations employing the LDA, PBE, PW91, WC, AM05, PBEsol
+and HSE06 exchange-correlation functionals. Diffusion Monte Carlo predicts a
+transition pressure of 14.0 +- 1.0 GPa slightly above the experimentally
+observed transition pressure range of 11.3 to 12.6 GPa. The HSE06 hybrid
+functional predicts a transition pressure of 12.4 GPa in excellent agreement
+with experiments. Exchange-correlation functionals using the local-density
+approximation and generalized-gradient approximations result in transition
+pressures ranging from 3.5 to 10.0 GPa, well below the experimental values. The
+transition pressure is sensitive to stress anisotropy. Anisotropy in the stress
+along any of the cubic axes of the diamond phase of silicon lowers the
+equilibrium transition pressure and may explain the discrepancy between the
+various experimental values as well as the small overestimate of the quantum
+Monte Carlo transition pressure.",1006.3253v1
+2010-06-21,Quarkonia in anisotropic hot QCD medium in a quasi-particle model,"The fate of heavy quarkonia states has been investigated in QCD at high
+temperature when the plasma has a small momentum space anisotropy within a
+quasi-particle model. A real time static potential has been obtained from a
+Hard thermal loop expression for the gluon self-energy, by employing the
+quasi-parton equilibrium distribution functions extracted from hot QCD
+equations of state of $O(g^5)$ and $O(g^6\ln(1/g))$. Employing the potential,
+quarkonia melting has been studied. It is found that the equations of state and
+the momentum anisotropy cause significant modifications in the screening
+properties of the plasma.",1006.3995v2
+2010-06-21,"Coherent magnetization precession in ferromagnetic (Ga,Mn)As induced by picosecond acoustic pulses","We show that the magnetization of a thin ferromagnetic (Ga,Mn)As layer can be
+modulated by picosecond acoustic pulses. In this approach a picosecond strain
+pulse injected into the structure induces a tilt of the magnetization vector M,
+followed by the precession of M around its equilibrium orientation. This effect
+can be understood in terms of changes in magneto-crystalline anisotropy induced
+by the pulse. A model where only one anisotropy constant is affected by the
+strain pulse provides a good description of the observed time-dependent
+response.",1006.4133v1
+2010-06-24,Mott transition in the Hubbard model on the anisotropic kagomé lattice,"We investigate the Mott transition in the anisotropic kagom\'e lattice
+Hubbard model using the cellular dynamical mean field theory combined with
+continuous-time quantum Monte Carlo simulations. By calculating the double
+occupancy and the density of states, we determine the interaction strength of
+the first-order Mott transition and show that it becomes small as the
+anisotropy increases. We also calculate the spin correlation functions and the
+single-particle spectrum, and reveal that the quasiparticle and magnetic
+properties change dramatically around the Mott transition; the spin
+correlations are strongly enhanced and the quasiparticle bands are deformed. We
+conclude that such dramatic changes are due to the enhancement of anisotropy
+associated with the relaxation of frustration around the Mott transition.",1006.4784v2
+2010-06-25,Epitaxial strain effects in the spinel ferrites CoFe2O4 and NiFe2O4 from first principles,"The inverse spinels CoFe2O4 and NiFe2O4, which have been of particular
+interest over the past few years as building blocks of artificial multiferroic
+heterostructures and as possible spin-filter materials, are investigated by
+means of density functional theory calculations. We address the effect of
+epitaxial strain on the magneto-crystalline anisotropy and show that, in
+agreement with experimental observations, tensile strain favors perpendicular
+anisotropy, whereas compressive strain favors in-plane orientation of the
+magnetization. Our calculated magnetostriction constants $\lambda_{100}$ of
+about -220 ppm for CoFe2O4 and -45 ppm for NiFe2O4 agree well with available
+experimental data. We analyze the effect of different cation arrangements used
+to represent the inverse spinel structure and show that both LSDA+U and GGA+U
+allow for a good quantitative description of these materials. Our results open
+the way for further computational investigations of spinel ferrites.",1006.5080v1
+2010-07-01,Highly-anisotropic and strongly-dissipative hydrodynamics for early stages of relativistic heavy-ion collisions,"We introduce a new framework of highly-anisotropic hydrodynamics that
+includes dissipation effects. Dissipation is defined by the form of the entropy
+source that depends on the pressure anisotropy and vanishes for the isotropic
+fluid. With a simple ansatz for the entropy source obeying general physical
+requirements, we are led to a non-linear equation describing the time evolution
+of the anisotropy in purely-longitudinal boost-invariant systems. Matter that
+is initially highly anisotropic approaches naturally the regime of the perfect
+fluid. Thus, the resulting evolution agrees with the expectations about the
+behavior of matter produced at the early stages of relativistic heavy-ion
+collisions. The equilibration is identified with the processes of entropy
+production.",1007.0130v1
+2010-07-06,Ferromagnetic phase of a uniaxial magnet with anisotropic biquadratic exchange,"The ferromagnetic phase (FMP) of a uniaxial magnet with the easy-plane
+single-ion anisotropy (SIA) and the anisotropic biquadra\-tic exchange
+interaction (BQEI) has been studied. The case $S=1$ for the site spin $S$ has
+been considered. Expressions for two branches of the spin excitation spectrum
+at finite temperatures $T$ have been obtained, and the conditions for spectral
+mode stability have been determined. The spectral mode stability diagram in the
+$T-h$ coordinates has been constructed. The diagram testifies that, under
+certain conditions, the temperature decrease is accompanied by a violation of
+the spectral mode stability followed, as the temperature decreases further, by
+its restoration; i.e. the reentrance phenomenon is observed. The temperature of
+the second-order phase transition (PT) from the FMP into the phase with
+spontaneously broken symmetry has been demonstrated to depend considerably on
+the BQEI anisotropy constant.",1007.0847v1
+2010-07-06,"Past Galactic GRBs, and the origin and composition of ultrahigh-energy cosmic rays","Recent results from the Pierre Auger Observatory show energy dependent
+chemical composition of ultrahigh-energy cosmic rays (UHECR) with a growing
+fraction of heavy elements at high energies. This points to a non-negligible
+contribution of the Galactic sources, such as past GRBs and other rare but
+powerful stellar explosions in the Milky Way. The effects of diffusion in the
+Galactic magnetic fields alter the observed composition and render the flux of
+UHECR isotropic, up to a few per cent anisotropy in the direction of the
+Galactic Center, as well as some small-scale anisotropy with ""hot spots"" due to
+the locations of the most recent/closest bursts.",1007.0961v1
+2010-07-07,Violation of Onsager Reciprocity in Underdoped Cuprates ?,"One of the canons of condensed matter physics is the Onsager Reciprocity
+principle in systems in which the Hamiltonian commutes with the time-reversal
+operator. Recent results of measurements of the Nernst coefficient in
+underdoped YBa_2Cu_30_{6+x}, together with the measurements of the anisotropy
+of conductivity and the inferred anisotropy of the thermopower, imply that this
+principle is violated. The probable violation and its temperature dependence
+are shown to be consistent with the Loop-current phase which has been directly
+observed in other experiments. The violation is related directly to the
+magneto-electric symmetry of such a phase in which an applied electric field
+generates an effective magnetic field at right angle to it and to the order
+parameter vector, and vice versa.",1007.1215v3
+2010-07-12,Neutrino Astrophysics and Galactic Cosmic Ray Anisotropy in IceCube,"The IceCube Observatory is a kilometer-cube neutrino telescope under
+construction at the South Pole and planned to be completed in early 2011. When
+completed it will consist of 5,160 Digital Optical Modules (DOMs) which detect
+Cherenkov radiation from the charged particles produced in neutrino
+interactions and by cosmic ray initiated atmospheric showers. IceCube
+construction is currently 90% complete. A selection of the most recent
+scientific results are shown here. The measurement of the anisotropy in arrival
+direction of galactic cosmic rays will also be presented and discussed.",1007.2621v2
+2010-07-20,Evidence for Dynamically Important Magnetic Fields in Molecular Clouds,"Recent observational evidence that magnetic fields are dynamically important
+in molecular clouds, compared to self-gravity and turbulence, is reviewed and
+illustrated with data from the NGC 2024 region. One piece of evidence,
+turbulence anisotropy, was found in the diffuse envelope of a cloud (Av~1;
+Heyer et al. 2008); our data further suggests turbulence anisotropy in the
+cloud (Av >7) and even near the cloud core (Av~100). The data also shows that
+magnetic fields can channel gravitational contraction even for a region with
+super-critical N(H2)/2Blos ratio (the ratio between the observed column density
+and two times the line-of-sight observed field strength), a parameter which has
+been widely used by observers to estimate core mass-to-flux ratios. Although
+the mass-to-flux ratio is constant under the flux-freezing condition, we show
+that N(H2)/2Blos grows with time if gravitational contraction is anisotropic
+due to magnetic fields.",1007.3312v2
+2010-07-20,Fractal Structure of Hastings-Levitov Patterns Restricted in a Sector Geometry,"A generalized form of the Hastings and Levitov (HL) algorithm for simulation
+of diffusion-limited aggregation (DLA) restricted in a sector geometry is
+studied. It is found that this generalization with uniform measure produces
+""wedge-like"" fractal patterns in the physical space, whose fractal dimension
+and anisotropy exponent depend significantly on the opening angle $\beta$ of
+the sector. The morphological properties and the overall shape of the patterns
+are analyzed by computing the angular two-point density correlation function of
+the patterns. We also find that the fractal dimension of the patterns with
+sinusoidal distributed measure depend weakly on $\beta$ with almost the same
+dimension as the radial DLA cluster. The anisotropy exponent and the visual
+appearance of the patterns in this case are shown to be compatible with those
+of the advection-diffusion-limited aggregation (ADLA) clusters.",1007.3358v1
+2010-07-23,Quantum Transport Through a Stretched Spin--1 Molecule,"We analyze the electronic transport through a model spin-1 molecule as a
+function of temperature, magnetic field and bias voltage. We consider the
+effect of magnetic anisotropy, which can be generated experimentally by
+stretching the molecule. In the experimentally relevant regime the conductance
+of the unstretched molecule reaches the unitary limit of the underscreened
+spin- 1 Kondo effect at low temperatures. The magnetic anisotropy generates an
+antiferromagnetic coupling between the remaining spin 1/2 and a singular
+density of quasiparticles, producing a second Kondo effect and a reduced
+conductance. The results explain recent measurements in spin-1 molecules
+[Science 328 1370 (2010)].",1007.4214v2
+2010-08-02,Temperature and bias voltage dependence of Co/Pd multilayer-based magnetic tunnel junctions with perpendicular magnetic anisotropy,"Temperature- and bias voltage-dependent transport measurements of magnetic
+tunnel junctions (MTJs) with perpendicularly magnetized Co/Pd electrodes are
+presented. Magnetization measurements of the Co/Pd multilayers are performed to
+characterize the electrodes. The effects of the Co layer thickness in the Co/Pd
+bilayers, the annealing temperature, the Co thickness at the MgO barrier
+interface, and the number of bilayers on the tunneling magneto resistance (TMR)
+effect are investigated. TMR-ratios of about 11 % at room temperature and 18.5
+% at 13 K are measured and two well-defined switching fields are observed. The
+results are compared to measurements of MTJs with Co-Fe-B electrodes and
+in-plane anisotropy.",1008.0341v1
+2010-08-10,Inverse Compton gamma-rays from Galactic dark matter annihilation: Anisotropy signatures,"High energy electrons and positrons from annihilating dark matter can imprint
+unique angular anisotropies on the diffuse gamma-ray flux by inverse Compton
+scattering off the interstellar radiation field. We develop a numerical tool to
+compute gamma-ray emission from such electrons and positrons produced in the
+smooth host halo and in substructure halos with masses down to 10^(-6)M_sun. We
+show that the angular power spectrum from inverse Compton scattering is
+exponentially suppressed below an angular scale determined by the diffusion
+length of electrons and positrons. We also find that the total flux and the
+shape of the angular power spectrum depends sensitively on the spatial
+distribution of subhalos in the Milky Way. Finally, the contribution from the
+smooth host halo component to the gamma-ray mean intensity is negligibly small
+compared to subhalos.",1008.1801v3
+2010-08-11,Theory for a dissipative droplet soliton excited by a spin torque nanocontact,"A novel type of solitary wave is predicted to form in spin torque oscillators
+when the free layer has a sufficiently large perpendicular anisotropy. In this
+structure, which is a dissipative version of the conservative droplet soliton
+originally studied in 1977 by Ivanov and Kosevich, spin torque counteracts the
+damping that would otherwise destroy the mode. Asymptotic methods are used to
+derive conditions on perpendicular anisotropy strength and applied current
+under which a dissipative droplet can be nucleated and sustained. Numerical
+methods are used to confirm the stability of the droplet against various
+perturbations that are likely in experiments, including tilting of the applied
+field, non-zero spin torque asymmetry, and non-trivial Oersted fields. Under
+certain conditions, the droplet experiences a drift instability in which it
+propagates away from the nanocontact and is then destroyed by damping.",1008.1898v1
+2010-08-11,Velocity Structure of Self-Similar Spherically Collapsed Halos,"Using a generalized self-similar secondary infall model, which accounts for
+tidal torques acting on the halo, we analyze the velocity profiles of halos in
+order to gain intuition for N-body simulation results. We analytically
+calculate the asymptotic behavior of the internal radial and tangential kinetic
+energy profiles in different radial regimes. We then numerically compute the
+velocity anisotropy and pseudo-phase-space density profiles and compare them to
+recent N-body simulations. For cosmological initial conditions, we find both
+numerically and analytically that the anisotropy profile asymptotes at small
+radii to a constant set by model parameters. It rises on intermediate scales as
+the velocity dispersion becomes more radially dominated and then drops off at
+radii larger than the virial radius where the radial velocity dispersion
+vanishes in our model. The pseudo-phase-space density is universal on
+intermediate and large scales. However, its asymptotic slope on small scales
+depends on the halo mass and on how mass shells are torqued after turnaround.
+The results largely confirm N-body simulations but show some differences that
+are likely due to our assumption of a one-dimensional phase space manifold.",1008.1980v2
+2010-08-13,Particle Systems arising from an anti-ferromagnetic Ising model,"We study a low temperature anisotropic anti-ferromagnetic 2D Ising model
+through the guise of a certain dimer model. This model has a bijection with a
+one-dimensional particle system equipped with creation and annihilation. In the
+thermodynamic limit, we determine the explicit phase diagrams as functions of
+temperature and anisotropy. Two values of the anisotropy are of particular
+interest - the 'critical' value and the 'independent' value. At independence,
+the particle system has the same distribution as the two colored noisy voter
+model. Its limiting measure under a natural scaling window is the Continuum
+Noisy Voter Model. At criticality, the distribution of particles on a given
+horizontal line, is a Pfaffian point process whose kernel in the scaling window
+can be written explicitly in terms of Bessel functions.",1008.2310v2
+2010-08-16,On the Sensitivity of Partial Redistribution Scattering Polarization Profiles to Various Atmospheric Parameters,"This paper presents a detailed study of the scattering polarization profiles
+formed under partial frequency redistribution (PRD) in two thermal models of
+the solar atmosphere. Particular attention is given to understanding the
+influence of several atmospheric parameters on the emergent fractional linear
+polarization profiles. The shapes of these $Q/I$ profiles are interpreted in
+terms of the anisotropy of the radiation field, which in turn depends on the
+source function gradient that sets the angular variation of the specific
+intensity. We define a suitable frequency integrated anisotropy factor for PRD
+that can be directly related to the emergent linear polarization. We show that
+complete frequency redistribution is a good approximation to model weak
+resonance lines. We also show that the emergent linear polarization profiles
+can be very sensitive to the thermal structure of the solar atmosphere and, in
+particular, to spatial variations of the damping parameter.",1008.2585v1
+2010-08-20,Destruction of chain-superconductivity in YBa_2Cu_4O_8 in a weak magnetic field,"We report measurements of the temperature dependent components of the
+magnetic penetration depth {\lambda}(T) in single crystal samples of
+YBa_2Cu_4O_8 using a radio frequency tunnel diode oscillator technique. We
+observe a downturn in {\lambda}(T) at low temperatures for currents flowing
+along the b and c axes but not along the a axis. The downturn in {\lambda}_b is
+suppressed by a small dc field of ~0.25 T. This and the zero field anisotropy
+of {\lambda}(T) likely result from proximity induced superconducting on the CuO
+chains, however we also discuss the possibility that a significant part of the
+anisotropy might originate from the CuO2 planes.",1008.3532v1
+2010-08-31,General Solution of EM Wave Propagation in Anisotropic Media,"When anisotropy is involved, the wave equation becomes simultaneous partial
+differential equations that are not easily solved. Moreover, when the
+anisotropy occurs due to both permittivity and permeability, these equations
+are insolvable without a numerical or an approximate method. The problem is
+essentially due to the fact neither $\e$ nor $\m$ can be extracted from the
+curl term, when they are in it. The terms $\na\times {\bf E}$ (or ${\bf H})$
+and $\na\times \e{\bf E}$ (or $\;\m{\bf H})$ are practically independent
+variables, and $\bf E$ and $\bf H$ are coupled to each other. However, if
+Maxwell's equations are manipulated in a different way, new wave equations are
+obtained. The obtained equations can be applied in anisotropic, as well as
+isotropic, cases. In addition, $\bf E$ and $\bf H$ are decoupled in the new
+equations, so the equations can be solved analytically by using tensor Green's
+functions.",1008.5212v1
+2010-09-01,Modeling mass independent of anisotropy,"By manipulating the spherical Jeans equation, Wolf et al. (2010) show that
+the mass enclosed within the 3D deprojected half-light radius r_1/2 can be
+determined with only mild assumptions about the spatial variation of the
+stellar velocity dispersion anisotropy as long as the projected velocity
+dispersion profile is fairly flat near the half-light radius, as is typically
+observed. They find M_1/2 = 3 \sigma_los^2 r_1/2 / G ~ 4 \sigma_los^2 R_eff /
+G, where \sigma_los^2 is the luminosity-weighted square of the line-of-sight
+velocity dispersion and R_eff is the 2D projected half-light radius. This
+finding can be used to show that all of the Milky Way dwarf spheroidal galaxies
+(MW dSphs) are consistent with having formed within a halo of mass
+approximately 3 x 10^9 M_sun assuming a LCDM cosmology. In addition, the
+dynamical I-band mass-to-light ratio (M/L) vs. M_1/2 relation for
+dispersion-supported galaxies follows a U-shape, with a broad minimum near M/L
+~ 3 that spans dwarf elliptical galaxies to normal ellipticals, a steep rise to
+M/L ~ 3,200 for ultra-faint dSphs, and a more shallow rise to M/L ~ 800 for
+galaxy cluster spheroids.",1009.0295v1
+2010-09-03,Anisotropy of Alfvénic Turbulence in the Solar Wind and Numerical Simulations,"We investigate the anisotropy of Alfv\'enic turbulence in the inertial range
+of slow solar wind and in both driven and decaying reduced magnetohydrodynamic
+simulations. A direct comparison is made by measuring the anisotropic
+second-order structure functions in both data sets. In the solar wind, the
+perpendicular spectral index of the magnetic field is close to -5/3. In the
+forced simulation, it is close to -5/3 for the velocity and -3/2 for the
+magnetic field. In the decaying simulation, it is -5/3 for both fields. The
+spectral index becomes steeper at small angles to the local magnetic field
+direction in all cases. We also show that when using the global rather than
+local mean field, the anisotropic scaling of the simulations cannot always be
+properly measured.",1009.0662v2
+2010-09-07,Search for light-speed anisotropies using Compton scattering of high-energy electrons,"Based on the high sensitivity of Compton scattering off ultra relativistic
+electrons, the possibility of anisotropies in the speed of light is
+investigated. The result discussed in this contribution is based on the
+gamma-ray beam of the ESRF's GRAAL facility (Grenoble, France) and the search
+for sidereal variations in the energy of the Compton-edge photons. The absence
+of oscillations yields the two-sided limit of 1.6 x 10^{-14} at 95 % confidence
+level on a combination of photon and electron coefficients of the minimal
+Standard Model Extension (mSME). This new constraint provides an improvement
+over previous bounds by one order of magnitude.",1009.1299v1
+2010-09-08,The decay of turbulence in rotating flows,"We present a parametric space study of the decay of turbulence in rotating
+flows combining direct numerical simulations, large eddy simulations, and
+phenomenological theory. Several cases are considered: (1) the effect of
+varying the characteristic scale of the initial conditions when compared with
+the size of the box, to mimic ""bounded"" and ""unbounded"" flows; (2) the effect
+of helicity (correlation between the velocity and vorticity); (3) the effect of
+Rossby and Reynolds numbers; and (4) the effect of anisotropy in the initial
+conditions. Initial conditions include the Taylor-Green vortex, the
+Arn'old-Beltrami-Childress flow, and random flows with large-scale energy
+spectrum proportional to $k^4$. The decay laws obtained in the simulations for
+the energy, helicity, and enstrophy in each case can be explained with
+phenomenological arguments that separate the decay of two-dimensional from
+three-dimensional modes, and that take into account the role of helicity and
+rotation in slowing down the energy decay. The time evolution of the energy
+spectrum and development of anisotropies in the simulations are also discussed.
+Finally, the effect of rotation and helicity in the skewness and kurtosis of
+the flow is considered.",1009.1595v2
+2010-09-10,Electric Field Controlled Magnetic Anisotropy in a Single Molecule,"We have measured quantum transport through an individual Fe$_4$
+single-molecule magnet embedded in a three-terminal device geometry. The
+characteristic zero-field splittings of adjacent charge states and their
+magnetic field evolution are observed in inelastic tunneling spectroscopy. We
+demonstrate that the molecule retains its magnetic properties, and moreover,
+that the magnetic anisotropy is significantly enhanced by reversible electron
+addition / subtraction controlled with the gate voltage. Single-molecule
+magnetism can thus be electrically controlled.",1009.2027v1
+2010-09-13,Anisotropy of Imbalanced Alfvenic Turbulence in Fast Solar Wind,"We present the first measurement of the scale-dependent power anisotropy of
+Elsasser variables in imbalanced fast solar wind turbulence. The dominant
+Elsasser mode is isotropic at lower spacecraft frequencies but becomes
+increasingly anisotropic at higher frequencies. The sub-dominant mode is
+anisotropic throughout, but in a scale-independent way (at higher frequencies).
+There are two distinct subranges exhibiting different scalings within what is
+normally considered the inertial range. The low Alfven ratio and shallow
+scaling of the sub-dominant Elsasser mode suggest an interpretation of the
+observed discrepancy between the velocity and magnetic field scalings. The
+total energy is dominated by the latter. These results do not appear to be
+fully explained by any of the current theories of incompressible imbalanced MHD
+turbulence.",1009.2427v2
+2010-09-14,Diagnosing Timing Error in WMAP Data,"The Doppler dipole signal dominates the cosmic microwave background (CMB)
+anisotropy maps obtained by the Wilkinson Microwave Anisotropy Probe (WMAP)
+mission, and plays a key role throughout the data processing. Previously, we
+discovered a timing asynchronism of -25.6ms between the timestamps of the
+spacecraft attitude and radiometer output in the original raw WMAP time-ordered
+data (TOD), which, if not corrected in following data processing, would
+generate an artificial quadrupole component (l=2) in recovered CMB maps (Liu,
+Xiong & Li 2010). Recently, Roukema (2010b) proves that there does exist a
+timing-offset-induced error corresponding to about -25.6ms in the WMAP
+calibrated TOD by studying the fluctuation variance per pixel in the
+temperature map recovered from the TOD as a function of assumed timing-offset.
+Here, we find evidence directly in the WMAP TOD for such an uncorrected timing
+error, possibly occurred in calculating the Doppler dipole signal during the
+WMAP team's TOD data processing. The amplitude is highly significant and is
+consistent with previous work. We also show that the uncorrected timing-offset
+can lead the WMAP CMB quadrupole to be substantially overestimated.",1009.2701v2
+2010-09-22,Local symmetry and magnetic anisotropy in multiferroic MnWO4 and antiferromagnetic CoWO4 studied by soft x-ray absorption spectroscopy,"Soft x-ray absorption experiments on the transition metal L2,3 edge of
+multiferroic MnWO4 and antiferromagnetic CoWO4 are presented. The observed
+linear polarization dependence, analyzed by full-multiplet calculations, is
+used to determine the ground state wave function of the magnetic Mn2+ and Co2+
+ions. The impact of the local structure and the spin-orbit coupling on the
+orbital moment is discussed in terms of the single-ion anisotropy. It is shown
+that the orbital moment in CoWO4 is responsible for the collinear
+antiferromagnetism, while the small size of spin-orbit coupling effects make
+spiral magnetic order in MnWO4 possible, enabling the material to be
+multiferroic.",1009.4338v1
+2010-10-03,Cation-ordering effects in the single layered manganite La(2/3)Sr(4/3)MnO4,"We have synthesized epitaxial La(1-x)Sr(1+x)MnO4 (x=1/3) films as random
+alloys and cation-ordered analogues to probe how cation order affects the
+properties of a 2D manganite. The films show weak ferromagnetic ordering up to
+130 K, although there is a dramatic difference in magnetic anisotropy depending
+on the cation order. While all films exhibit similar gapped insulator behavior
+above 130 K, there is a significant difference in the low temperature transport
+mechanism depending on the cation order. Differences in magnetic anisotropy and
+low temperature transport are consistent with differences in Mn 3d orbital
+occupancies. Together this work suggests that cation ordering can significantly
+alter the Mn 3d orbital ground state in these correlated electron systems.",1010.0372v2
+2010-10-04,Improved Dark Energy Detection through the Polarization-assisted WMAP-NVSS ISW Correlation,"Integrated Sachs-Wolfe (ISW) effect can be estimated by cross-correlating
+Cosmic Microwave Background (CMB) sky with tracers of the local matter
+distribution. At late cosmic time, the dark energy induced decay of gravitation
+potential generates a cross-correlation signal on large angular scales. The
+dominant noise are the intrinsic CMB anisotropies from the inflationary epoch.
+In this Letter we use CMB polarization to reduce this intrinsic noise. We
+cross-correlate the microwave sky observed by Wilkinson Microwave Anisotropy
+Probe (WMAP) with the radio source catalog compiled by NRAO VLA Sky Survey
+(NVSS) to study the efficiency of the noise suppression . We find that the
+error bars are reduced about 5-12 %, improving the statistical power.",1010.0578v1
+2010-10-10,Anisotropy of Magnetoresistance Hysteresis around the $ν=2/3$ Quantum Hall State in Tilted Magnetic Field,"We present an anisotropy of the hysteretic transport around the spin
+transition point at Landau level filling factor $\nu=2/3$ in tilted magnetic
+field. When the direction of the in-plane component of the magnetic field
+$B_{\parallel}$ is normal to the probe current $I$, a strong hysteretic
+transport due to the current-induced nuclear spin polarization occurs. When
+$B_{\parallel}$ is parallel to $I$, on the other hand, the hysteresis almost
+disappears. We also demonstrate that the nuclear spin-lattice relaxation rate
+$T_{1}^{-1}$ at the transition point increases with decreasing angle between
+the directions of $B_{\parallel}$ and $I$. These results suggest that the
+morphology of electron spin domains around $\nu =2/3$ is affected by the
+current direction.",1010.1885v1
+2010-10-15,Realizing bright matter-wave soliton collisions with controlled relative phase,"We propose a method to split the ground state of an attractively interacting
+atomic Bose-Einstein condensate into two bright solitary waves with controlled
+relative phase and velocity. We analyze the stability of these waves against
+their subsequent re-collisions at the center of a cylindrically symmetric,
+prolate harmonic trap as a function of relative phase, velocity, and trap
+anisotropy. We show that the collisional stability is strongly dependent on
+relative phase at low velocity, and we identify previously unobserved
+oscillations in the collisional stability as a function of the trap anisotropy.
+An experimental implementation of our method would determine the validity of
+the mean field description of bright solitary waves, and could prove an
+important step towards atom interferometry experiments involving bright
+solitary waves.",1010.3219v2
+2010-10-18,Significant elastic anisotropy in Ti$_{1-x}$Al$_x$N alloys,"Strong compositional-dependent elastic properties have been observed
+theoretically and experimentally in Ti$_{1-x}$Al$_x$ N alloys. The elastic
+constant, C$_{11}$, changes by more than 50% depending on the Al-content.
+Increasing the Al-content weakens the average bond strength in the local
+octahedral arrangements resulting in a more compliant material. On the other
+hand, it enhances the directional (covalent) nature of the nearest neighbor
+bonds that results in greater elastic anisotropy and higher sound velocities.
+The strong dependence of the elastic properties on the Al-content offers new
+insight into the detailed understanding of the spinodal decomposition and age
+hardening in Ti$_{1-x}$Al$_x$N alloys.",1010.3678v1
+2010-10-21,A model for vortex formation in magnetic nanodots,"We use Monte Carlo simulation to study the vortex nucleation on magnetic
+nanodots at low temperature. In our simulations, we have considered a simple
+microscopic two-dimensional anisotropic Heisenberg model with term to describe
+the anisotropy due to the presence of the nanodot edge. We have considered the
+thickness of the edge, which was not considered in previous works, introducing
+a term that controls the energy associated to the edge. Our results clearly
+show that the thickness of the edge has a considerable influence in the vortex
+nucleation on magnetic nanodots. We have obtained the hysteresis curve for
+several values of the surface anisotropy and skin depth parameter ($\xi$). The
+results are in excellent agreement with experimental data.",1010.4541v1
+2010-10-21,Van der Waals torque induced by external magnetic fields,"We present a method for inducing and controlling van der Waals torques
+between two parallel slabs using a constant magnetic field. The torque is
+calculated using the Barash theory of dispersive torques. In III-IV
+semiconductors such as $InSb$, the effect of an external magnetic field is to
+induce an optical anisotropy, in an otherwise isotropic material, that will in
+turn induce a torque.
+  The calculations of the torque are done in the Voigt configuration, with the
+magnetic field parallel to the surface of the slabs. As a case study we
+consider a slab made of calcite and a second slab made of $InSb$. In the
+absence of magnetic field there is no torque. As the magnetic field increases,
+the optical anisotropy of $InSb$ increases and the torque becomes different
+from zero, increasing with the magnetic field. The resulting torque is of the
+same order of magnitude as that calculated using permanent anisotropic
+materials when the magnetic fields is close to 1 T.",1010.4553v1
+2010-10-22,Thermally activated magnetization reversal in monoatomic magnetic chains on surfaces studied by classical atomistic spin-dynamics simulations,"We analyze the spontaneous magnetization reversal of supported monoatomic
+chains of finite length due to thermal fluctuations via atomistic spin-dynamics
+simulations. Our approach is based on the integration of the Landau-Lifshitz
+equation of motion of a classical spin Hamiltonian at the presence of
+stochastic forces. The associated magnetization lifetime is found to obey an
+Arrhenius law with an activation barrier equal to the domain wall energy in the
+chain. For chains longer than one domain-wall width, the reversal is initiated
+by nucleation of a reversed magnetization domain primarily at the chain edge
+followed by a subsequent propagation of the domain wall to the other edge in a
+random-walk fashion. This results in a linear dependence of the lifetime on the
+chain length, if the magnetization correlation length is not exceeded. We
+studied chains of uniaxial and tri-axial anisotropy and found that a tri-axial
+anisotropy leads to a reduction of the magnetization lifetime due to a higher
+reversal attempt rate, even though the activation barrier is not changed.",1010.4730v2
+2010-10-25,Quarkonium in a non-ideal hot QCD Plasma,"Substantial anisotropies should occur in the hot expanding QCD plasma
+produced in relativistic heavy-ion collisions due to non-vanishing shear
+viscosity. We discuss the form of the real-time, hard thermal loop resummed
+propagator for static gluons in the presence of such anisotropies and the
+consequences for quarkonium binding. It has been predicted that the propagator
+develops an imaginary part due to Landau damping at high temperature. This
+generates a much larger width of quarkonium states than the Appelquist-Politzer
+vacuum estimate corresponding to decay into three gluons. We argue that this
+might be observable in heavy-ion collisions as a suppression of the Upsilon(1S)
+--> e+ e- process. Lastly, we consider the heavy quark (singlet) free energy
+just above the deconfinement temperature. In the ""semi-QGP"", F(R) at distances
+beyond 1/T is expected to be suppressed by 1/N as compared to an ideal plasma.",1010.5218v1
+2010-10-25,Second Order Phase Transition in Anisotropic Lattice Gauge Theories with Extra Dimensions,"Field theories with extra dimensions live in a limbo. While their classical
+solutions have been the subject of considerable study, their quantum aspects
+are difficult to control. A special class of such theories are anisotropic
+gauge theories. The anisotropy was originally introduced to localize chiral
+fermions. Their continuum limit is of practical interest and it will be shown
+that the anisotropy of the gauge couplings plays a crucial role in opening the
+phase diagram of the theory to a new phase, that is separated from the others
+by a second order phase transition. The mechanism behind this is generic for a
+certain class of models, that can be studied with lattice techniques. This
+leads to new perspectives for the study of quantum effects of extra dimensions.",1010.5281v1
+2010-10-27,Orientation Effects on the Inner Region of Dusty Torus of Active Galactic Nuclei,"A sublimation process governs the innermost region of the dusty torus of
+active galactic nuclei. However, the observed inner radius of the torus is
+systematically smaller than the expected radius by a factor of ~ 1/3. We show
+that the anisotropy of the emission from accretion disks resolves this conflict
+naturally and quantitatively. An accretion disk emits lesser radiation in the
+direction closer to its equatorial plane (i.e., to the torus). We find that the
+anisotropy makes the torus inner region closer to the central black hole and
+concave. Moreover, the innermost edge of the torus may connect with the
+outermost edge of the disk continuously. Considering the anisotropic emission
+of each clump in the torus, we calculate the near-infrared flux variation in
+response to a UV flash. For an observer at the polar angle theta_obs = 25 deg,
+the centroid of the time delay is found to be 37% of the delay expected in the
+case of isotropic illumination, which explains the observed systematic
+deviation.",1010.5799v1
+2010-10-28,"Interplay of the Kondo Effect and Spin-Polarized Transport in Magnetic Molecules, Adatoms and Quantum Dots","We study the interplay of the Kondo effect and spin-polarized tunneling in a
+class of systems exhibiting uniaxial magnetic anisotropy, such as magnetic
+molecules, magnetic adatoms, or quantum dots coupled to a single localized
+magnetic moment. Using the numerical renormalization group method we calculate
+the spectral functions and linear conductance in the Kondo regime. We show that
+the exchange coupling between conducting electrons and localized magnetic core
+generally leads to suppression of the Kondo effect. We also predict a
+nontrivial dependence of the tunnel magnetoresistance on the strength of
+exchange coupling and on the anisotropy constant.",1010.6030v2
+2010-11-01,Crossover phenomena involving the dense O($n$) phase,"We explore the properties of the low-temperature phase of the O($n$) loop
+model in two dimensions by means of transfer-matrix calculations and
+finite-size scaling. We determine the stability of this phase with respect to
+several kinds of perturbations, including cubic anisotropy, attraction between
+loop segments, double bonds and crossing bonds. In line with Coulomb gas
+predictions, cubic anisotropy and crossing bonds are found to be relevant and
+introduce crossover to different types of behavior. Whereas perturbations in
+the form of loop-loop attractions and double bonds are irrelevant, sufficiently
+strong perturbations of these types induce a phase transition of the Ising
+type, at least in the cases investigated. This Ising transition leaves the
+underlying universal low-temperature O($n$) behavior unaffected.",1011.0302v1
+2010-11-01,Level crossings and zero-field splitting in the \{Cr$_8$\}-cubane spin-cluster by inelastic neutron scattering and magnetization studies,"Inelastic neutron scattering in variable magnetic field and high-field
+magnetization measurements, at the milikelvin temperature range, were performed
+to gain insight into the low-energy magnetic excitation spectrum and the
+field-induced level crossings in the molecular spin cluster \{Cr$_8$\}-cubane.
+These complementary techniques provide consistent estimates of the lowest
+level-crossing field. The overall features of the experimental data are
+explained using an isotropic Heisenberg model, based on three distinct exchange
+interactions linking the eight Cr$^{\text{III}}$ paramagnetic centers (spins $s
+= 3/2$), that is supplemented with a relatively large molecular magnetic
+anisotropy term for the lowest S=1 multiplet. It is noted that the existence of
+the anisotropy is clearly evident from the magnetic field dependence of the
+excitations in the INS measurements, while the magnetization measurements are
+not sensitive to its effects.",1011.0364v1
+2010-11-01,"Magnetic phase diagram of spatially anisotropic, frustrated spin-1/2 Heisenberg antiferromagnet on a stacked square lattice","Magnetic phase diagram of a spatially anisotropic, frustrated spin-1/2
+Heisenberg antiferromagnet on a stacked square lattice is investigated using
+second-order spin-wave expansion. The effects of interlayer coupling and the
+spatial anisotropy on the magnetic ordering of two ordered ground states are
+explicitly studied. It is shown that with increase in next nearest neighbor
+frustration the second-order corrections play a significant role in stabilizing
+the magnetization. We obtain two ordered magnetic phases (Neel and stripe)
+separated by a paramagnetic disordered phase. Within second-order spin-wave
+expansion we find that the width of the disordered phase diminishes with
+increase in the interlayer coupling or with decrease in spatial anisotropy but
+it does not disappear. Our obtained phase diagram differs significantly from
+the phase diagram obtained using linear spin-wave theory.",1011.0381v2
+2010-11-08,Heavy Ion Initial Conditions and Correlations Between Higher Moments in the Spatial Anisotropy,"Fluctuations in the initial conditions for relativistic heavy ion collisions
+are proving to be crucial to understanding final state flow and jet quenching
+observables. The initial geometry has been parametrized in terms of moments in
+the spatial anisotropy (i.e. $\epsilon_2, \epsilon_3, \epsilon_4,
+\epsilon_5...$), and it has been stated in multiple published articles that the
+vector directions of odd moments are uncorrelated with the even moments and the
+reaction place angle. In this article, we demonstrate that this is incorrect
+and that a substantial correlation exists between the even and odd moments in
+peripheral Au+Au collisions. These correlations persist for all centralities,
+though at a very small level for the 0-55% most central collisions.",1011.1853v2
+2010-11-09,Structural change of vortex patterns in anisotropic Bose-Einstein condensates,"We study the changes in the spatial distribution of vortices in a rotating
+Bose-Einstein condensate due to an increasing anisotropy of the trapping
+potential. Once the rotational symmetry is broken, we find that the vortex
+system undergoes a rich variety of structural changes, including the formation
+of zig-zag and linear configurations. These spatial re-arrangements are well
+signaled by the change in the behavior of the vortex-pattern eigenmodes against
+the anisotropy parameter. The existence of such structural changes opens up
+possibilities for the coherent exploitation of effective many-body systems
+based on vortex patterns.",1011.2125v3
+2010-11-13,Optical Dielectric Functions of III-V Semiconductors in Wurtzite Phase,"Optical properties of semiconductors can exhibit strong polarization
+dependence due to crystalline anisotropy. A number of recent experiments have
+shown that the photoluminescence intensity in free standing nanowires is
+polarization dependent. One contribution to this effect is the anisotropy of
+the dielectric function due to the fact that most nanowires crystalize in the
+wurtzite form. While little is known experimentally about the band structures
+wurtzite phase III-V semiconductors, we have previously predicted the bulk band
+structure of nine III-V semiconductors in wurtzite phase.Here, we predict the
+frequency dependent dielectric functions for nine non-Nitride wurtzite phase
+III-V semiconductors (AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs and InSb).
+Their complex dielectric functions are calculated in the dipole approximation
+by evaluating the momentum matrix elements on a dense grid of special k-points
+using empirical pseudopotential wave functions. Corrections to the momentum
+matrix elements accounting for the missing core states are made using a scaling
+factor which is determined by using the optical sum rules on the calculated
+dielectric functions for the zincblende polytypes. The dielectric function is
+calculated for polarizations perpendicular and parallel to the c-axis of the
+crystal.",1011.3081v1
+2010-11-25,First-principles investigation of the very large Perpendicular Magnetic Anisotropy at Fe|MgO Interfaces,"The perpendicular magnetic anisotropy (PMA) arising at the interface between
+ferromagnetic transition metals and metallic oxides are investigated via
+first-principles calculations. In this work very large values of PMA up to 3
+erg/cm$^2$ at Fe$|$MgO interfaces are reported in agreement with recent
+experiments. The origin of PMA is attributed to overlap between O-$p_z$ and
+transition metal $d_{z^2}$ orbitals hybridized with $d_{xz(yz)}$ orbitals with
+stronger spin-orbit coupling induced splitting around the Fermi level for
+perpendicular magnetization orientation. Furthemore, it is shown that the PMA
+value weakens in case of over- or underoxidation when oxygen $p_z$ and
+transition metal $d_{z^2}$ orbitals overlap is strongly affected by disorder,
+in agreement with experimental observations in magnetic tunnel junctions.",1011.5667v1
+2010-12-03,Origin of In-Plane Anisotropy in Optical Conductivity for Antiferromagnetic Metallic Phase of Iron Pnictides,"We examine the optical conductivity in antiferromagnetic (AFM) iron pnictides
+by mean-field calculation in a five-band Hubbard model. The calculated spectra
+are well consistent with the in-plane anisotropy observed in the measurements,
+where the optical conductivity along the direction with the AFM alignment of
+neighboring spins is larger than that along the ferromagnetic (FM) direction in
+the low-energy region; however, that along the FM direction becomes larger in
+the higher-energy region. The difference between the two directions is
+explained by taking account of orbital characters in both occupied and
+unoccupied states as well as of the nature of Dirac-type linear dispersions
+near the Fermi level.",1012.0670v2
+2010-12-03,Measurement of anisotropies in the large-scale diffuse gamma-ray emission,"We have performed the first measurement of the angular power spectrum in the
+large-scale diffuse emission at energies from 1-50 GeV. We compared results
+from data and a simulated model in order to identify significant differences in
+anisotropy properties. We found angular power above the photon noise level in
+the data at multipoles greater than ~ 100 for energies 1< E <10 GeV. The excess
+power in the data suggests a contribution from a point source population not
+present in the model.",1012.0755v3
+2010-12-05,Weak field magnetoresistance of narrow-gap semiconductor InSb,"The weak antilocalization effect of InSb film in perpendicular as well as
+tilted magnetic field is investigated. It is found that the InSb film has
+quasi-two-dimensional feature and the Nyquist mechanism dominates decoherence.
+The two dimensionality is also verified further and the influence of roughness
+effect and Zeeman effect on weak antilocalization effect is studied by
+systematically investigating the anisotropy of weak field magnetoresistance
+with respect to magnetic field. It is also found that the existence of in-plane
+field can effectively suppress the weak antilocalization effect of InSb film
+and the roughness effect plays an important role in the anisotropy.",1012.0968v1
+2010-12-07,Jc Scaling and Anisotropies in Co-doped Ba-122 thin films,"We have successfully grown epitaxial, superconducting films of
+Ba(Fe1-xCox)2As2 (Ba-122)with x ~ 0.1. The films grow without observable
+correlated defects parallel to the c-axis, as confirmed by TEM. This is also
+reflected in the absence of a caxis peak in Jc({\theta}). In contrast to
+cuprate high-Tc superconductors such as YBa2Cu3O7-d or even Bi2Sr2Ca2Cu3O10-d,
+the pnictides show a rather low anisotropic behavior in their Jc({\theta})
+behavior as well as in their upper critical fields, Hc2. As a multiband
+superconductor, Ba-122 exhibits a temperature dependent electronic mass
+anisotropy.",1012.1523v1
+2010-12-07,$π^{0}$ Azimuthal Anisotropy in Au+Au Collisions at $\sqrt{s_{NN}}=39-200$ GeV from PHENIX: Collision Energy and Path-Length Dependence of Jet-Quenching and the Role of Initial Geometry,"The azimuthal anisotropy of high $p_{T}$ particle production in heavy ion
+collisions is a sensitive probe of the jet quenching mechanism. Recent PHENIX
+measurements for Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV show a $\pi^{0}$
+$v_{2}$ signal that exceeds the pQCD energy loss calculations up to $p_{T} \sim
+10$ GeV/c, challenging the traditional perturbative picture of the energy loss
+process. Here, we present an update and details of that measurement, as well as
+new high $p_T$ measurements at $\sqrt{s_{NN}}=62$ and 39 GeV. These
+measurements not only provide an important constraint for understanding the
+path-length dependence of jet energy loss and the role of initial collision
+geometry, but also allow a search for the onset of jet quenching as
+$\sqrt{s_{NN}}$ is varied.",1012.1639v1
+2010-12-13,Do Cosmological Perturbations Have Zero Mean?,"A central assumption in our analysis of cosmic structure is that cosmological
+perturbations have zero ensemble mean. This property is one of the consequences
+of statistically homogeneity, the invariance of correlation functions under
+spatial translations. In this article we explore whether cosmological
+perturbations indeed have zero mean, and thus test one aspect of statistical
+homogeneity. We carry out a classical test of the zero mean hypothesis against
+a class of alternatives in which perturbations have non-vanishing means, but
+homogeneous and isotropic covariances. Apart from Gaussianity, our test does
+not make any additional assumptions about the nature of the perturbations and
+is thus rather generic and model-independent. The test statistic we employ is
+essentially Student's t statistic, applied to appropriately masked,
+foreground-cleaned cosmic microwave background anisotropy maps produced by the
+WMAP mission. We find evidence for a non-zero mean in a particular range of
+multipoles, but the evidence against the zero mean hypothesis goes away when we
+correct for multiple testing. We also place constraints on the mean of the
+temperature multipoles as a function of angular scale. On angular scales
+smaller than four degrees, a non-zero mean has to be at least an order of
+magnitude smaller than the standard deviation of the temperature anisotropies.",1012.2849v1
+2010-12-15,Strong correlations and the anisotropy of acceptor states in insulating La(2-x)Sr(x)CuO(4),"We use the Green's function formalism to discuss the role of strong
+correlations to the spatial structure of acceptor states doped into a
+two-dimensional Mott-Hubbard antiferromagnetic insulator. When the scattering
+between doped carriers, at the nesting wave vector ${\bf Q}=(\pi,\pi)$, is
+strong enough to produce a momentum dependent scattering rate, $\Gamma_{\bf
+k}$, the corresponding acceptor states become spatially anisotropic. As an
+example, we calculate the spatial structure of an acceptor state bound to an
+attractive two-dimensional Dirac delta potential, for a simple form of
+$\Gamma_{\bf k}$. We then discuss the role of such spatial anisotropy for the
+understanding of an apparent discrepancy between low temperature transport data
+and photoemission spectra in lightly doped La(2-x)Sr(x)CuO(4).",1012.3302v1
+2010-12-23,Confinement-induced Resonances in Quasi-one-dimensional Traps with Transverse Anisotropy,"We study atom-atom scattering in quasi-one-dimensional geometries with
+transverse anisotropy. By assuming an s-wave pseudo-potential of contact
+interaction, we show that the system would exhibit a single confinement-induced
+resonance, where the scattering process degenerates to a total reflection as a
+one-dimensional gas of impenetrable bosons. For a general form of interaction,
+we present a formal calculation based on the two-channel model and conclude the
+existence of only one confinement-induced resonance. Our findings are
+inconsistent with a recent experiment by Haller et al. [Phys. Rev. Lett. 104,
+153203 (2010)], where a splitting of confinement-induced resonances has been
+observed in an anisotropic quasi-one-dimensional quantum gas of Cs atoms.",1012.5156v1
+2010-12-27,Testing the Isotropy of the Universe with Type Ia Supernovae,"We analyze the magnitude-redshift data of type Ia supernovae included in the
+Union and Union2 compilations in the framework of an anisotropic Bianchi type I
+cosmological model and in the presence of a dark energy fluid with anisotropic
+equation of state. We find that the amount of deviation from isotropy of the
+equation of state of dark energy, the skewness \delta, and the present level of
+anisotropy of the large-scale geometry of the Universe, the actual shear
+\Sigma_0, are constrained in the ranges -0.16 < \delta < 0.12 and -0.012 <
+\Sigma_0 < 0.012 (1\sigma C.L.) by Union2 data. Supernova data are then
+compatible with a standard isotropic universe (\delta = \Sigma_0 = 0), but a
+large level of anisotropy, both in the geometry of the Universe and in the
+equation of state of dark energy, is allowed.",1012.5596v2
+2010-12-29,Correspondence between HBT radii and the emission zone in non-central heavy ion collisions,"In non-central collisions between ultra-relativistic heavy ions, the
+freeze-out distribution is anisotropic, and its major longitudinal axis may be
+tilted away from the beam direction. The shape and orientation of this
+distribution are particularly interesting, as they provide a snapshot of the
+evolving source and reflect the space-time aspect of anisotropic flow.
+Experimentally, this information is extracted by measuring pion HBT radii as a
+function of angle with respect to the reaction plane. Existing formulae
+relating the oscillations of the radii and the freezeout anisotropy are in
+principle only valid for Gaussian sources with no collective flow. With a
+realistic transport model of the collision, which generates flow and
+non-Gaussian sources, we find that these formulae approximately reflect the
+anisotropy of the freezeout distribution.",1012.5941v1
+2011-01-03,Superconductivity at 32K and anisotropy in Tl0.58Rb0.42Fe1.72Se2 crystals,"Single crystals of Tl0.58Rb0.42Fe1.72Se2 are successfully grown with the
+superconducting transition temperatures Tconset=32K and Tczero=31.4K. The Hall
+coefficient exhibits a multi-band behavior, which is very similar to that of
+all other Fe-based superconductors. We found that the susceptibility at the
+normal state decreases with decreasing the temperature, indicating a strong
+antiferromagnetic (AFM) spin fluctuation at the normal state, which might be
+related to the superconductivity (SC). We also determined the upper critical
+fields in ab-plane and along c-axis. The anisotropy of the superconductivity
+determined by the ratio of Hc2ab and Hc2c is estimated to 5.0, which is larger
+than that in (Ba,K)Fe2As2 and BaFe2-xCoxAs2, but smaller than that in cuprate
+superconductors.",1101.0462v1
+2011-01-06,Ordered moment in the anisotropic and frustrated square lattice Heisenberg model,"The two-dimensional frustrated next nearest neighbor Heisenberg model on the
+square lattice is a prime example for a spin system where quantum fluctuations
+can either destroy or stabilize magnetic order. The phase boundaries and
+staggered moment dependence on the frustration ratio J_2/J_1 of the exchange
+constants are fairly well understood both from approximate analytical and
+numerical methods. In this work we use exact diagonalization for finite
+clusters for an extensive investigation of the more general J_1a,b-J_2 model
+which includes a spatial exchange anisotropy between next-neighbor spins. We
+introduce a systematic way of tiling the square lattice and, for this low
+symmetry model, define a controlled procedure for the finite size scaling that
+is compatible with the possible magnetic phases. We obtain ground state
+energies, structure factors and ordered moments and compare with the results of
+spin wave calculations. We conclude that J_1a,b exchange anisotropy strongly
+stabilizes the columnar antiferromagnetic phase for all frustration parameters,
+in particular in the region of the spin nematic phase of the isotropic model.",1101.1181v2
+2011-01-07,Competing phases in spin-1/2 J1-J2 chain with easy-plane anisotropy,"We summarize our theoretical findings on the ground-state phase diagram of
+the spin-1/2 XXZ chain having competing nearest-neighbor (J1) and
+antiferromagnetic next-nearest-neighbor (J2) couplings. Our study is mainly
+concerned with the case of ferromagnetic J1, and the case of antiferromagnetic
+J1 is briefly reviewed for comparison. The phase diagram contains a rich
+variety of phases in the plane of J1/J2 versus the XXZ anisotropy Delta:
+vector-chiral phases, N\'eel phases, several dimer phases, and
+Tomonaga-Luttinger liquid phases. We discuss the vector-chiral order that
+appears for a remarkably wide parameter space, successive N\'eel-dimer phase
+transitions, and an emergent nonlocal string order in a narrow region of
+ferromagnetic J1 side.",1101.1374v2
+2011-01-07,Disorder effects at a nematic quantum critical point in d-wave cuprate superconductor,"A d-wave high temperature cuprate superconductor exhibits a nematic ordering
+transition at zero temperature. Near the quantum critical point, the coupling
+between gapless nodal quasiparticles and nematic order parameter fluctuation
+can result in unusual behaviors, such as extreme anisotropy of fermion
+velocities. We study the disorder effect on the nematic quantum critical
+behavior and especially on the flow of fermion velocities. The disorders that
+couple to nodal quasiparticles are divided into three types: random mass,
+random gauge field, and random chemical potential. A renormalization group
+analysis shows that random mass and random gauge field are both irrelevant and
+thus do not change the fixed point of extreme velocity anisotropy. However, the
+marginal interaction due to random chemical potential destroys this fixed point
+and makes the nematic phase transition unstable.",1101.1551v3
+2011-01-17,The upper critical field and its anisotropy in LiFeAs,"The upper critical field $\mu_0H_{c2}(T_c)$ of LiFeAs single crystals has
+been determined by measuring the electrical resistivity using the facilities of
+pulsed magnetic field at Los Alamos. We found that $\mu_0H_{c2}(T_c)$ of LiFeAs
+shows a moderate anisotropy among the layered iron-based superconductors; its
+anisotropic parameter $\gamma$ monotonically decreases with decreasing
+temperature and approaches $\gamma\simeq 1.5$ as $T\rightarrow 0$. The upper
+critical field reaches 15T ($H\parallel c$) and 24.2T ($H\parallel ab$) at
+$T=$1.4K, which value is much smaller than other iron-based high $T_c$
+superconductors. The temperature dependence of $\mu_0H_{c2}(T_c)$ can be
+described by the Werthamer-Helfand-Hohenberg (WHH) method, showing orbitally
+and (likely) spin-paramagnetically limited upper critical field for $H\parallel
+c$ and $H\parallel ab$, respectively.",1101.3159v1
+2011-01-20,Distortion of the ultrahigh energy cosmic ray flux from rare transient sources in inhomogeneous extragalactic magnetic fields,"Detecting and characterizing the anisotropy pattern of the arrival directions
+of the highest energy cosmic rays are crucial steps towards the identification
+of their sources. We discuss a possible distortion of the cosmic ray flux
+induced by the anisotropic and inhomogeneous distribution of extragalactic
+magnetic fields in cases where sources of ultrahigh energy cosmic rays are rare
+transient phenomena, such as gamma-ray bursts and/or newly born magnetars. This
+distortion does not involve an angular deflection but the modulation of the
+flux related to the probability of seeing the source on an experiment lifetime.
+To quantify this distortion, we construct sky maps of the arrival directions of
+these highest energy cosmic rays for various magnetic field configurations and
+appeal to statistical tests proposed in the literature. We conclude that this
+distortion cannot affect present experiments but should be considered when
+performing anisotropy studies with future large-scale experiments that record
+as many as hundreds of events above 6x10^19 eV.",1101.3801v1
+2011-01-24,Quarkonium states in a complex-valued potential,"We calculate quarkonium binding energies using a realistic complex-valued
+potential for both an isotropic and anisotropic quark-gluon plasma. We
+determine the disassociation temperatures of the ground and first excited
+states considering both the real and imaginary parts of the binding energy. We
+show that the effect of momentum-space anisotropy is smaller on the imaginary
+part of the binding energy than on the real part of the binding energy. In the
+case that one assumes an isotropic plasma, we find disassociation temperatures
+for the J/psi, Upsilon and chi_b of 1.6 T_c, 2.8 T_c, and 1.5 T_c,
+respectively. We find that a finite oblate momentum-space anisotropy increases
+the disassociation temperature for all states considered and results in a
+splitting of the p-wave states associated with the chi_b first excited state of
+bottomonium.",1101.4651v4
+2011-01-27,Transport in superlattices on single layer graphene,"We study transport in undoped graphene in the presence of a superlattice
+potential both within a simple continuum model and using numerical
+tight-binding calculations. The continuum model demonstrates that the
+conductivity of the system is primarily impacted by the velocity anisotropy
+that the Dirac points of graphene develop due to the potential. For
+one-dimensional superlattice potentials, new Dirac points may be generated, and
+the resulting conductivities can be approximately described by the anisotropic
+conductivities associated with each Dirac point. Tight-binding calculations
+demonstrate that this simple model is quantitatively correct for a single Dirac
+point, and that it works qualitatively when there are multiple Dirac points.
+Remarkably, for a two dimensional potential which may be very strong but
+introduces no anisotropy in the Dirac point, the conductivity of the system
+remains essentially the same as when no external potential is present.",1101.5270v1
+2011-01-31,Estimation of isotropization time ($τ_{\rm iso}$) of QGP from direct photons,"We calculate transverse momentum distribution of direct photons from various
+sources by taking into account the initial state momentum anisotropy of quark
+gluon plasma (QGP). The total photon yield is then compared with the recent
+measurement of photon transverse momentum distribution by the PHENIX
+collaboration. It is also demonstrated that the presence of such an anisotropy
+can describe the PHENIX photon data better than the isotropic case in the
+present model. We show that the isotropization time thus extracted lies within
+the range $1.5 \geq\tau_{\rm iso} \geq 0.5$ fm/c for the initial condition used
+here.",1101.5857v1
+2011-02-02,Effect of finite temperature and uniaxial anisotropy on the Casimir effect with three-dimensional topological insulators,"In this work we study the Casimir effect with three-dimensional topological
+insulators including the effects of temperature and uniaxial anisotropy.
+Although precise experimental values for the optical properties of these
+materials are yet to be established, qualitative analysis is still possible. We
+find qualitatively that the reported repulsive behavior and the equilibrium
+point are robust features of the system, and are favored by low temperatures
+and the enhancement of the optical response parallel to the optical axis. The
+dependence of the equilibrium point with temperature and with the topological
+magnetoelectric polarizability characteristic of three-dimensional topological
+insulators is also discussed.",1102.0455v2
+2011-02-04,Tuning of the spin-orbit interaction in a quantum dot by an in-plane magnetic field,"Using an exact diagonalization approach we show that one- and two-electron
+InAs quantum dots exhibit avoided crossing in the energy spectra that are
+induced by the spin-orbit coupling in the presence of an in-plane external
+magnetic field. The width of the avoided crossings depends strongly on the
+orientation of the magnetic field which reveals the intrinsic anisotropy of the
+spin-orbit coupling interactions. We find that for specific orientations of the
+magnetic field avoided crossings vanish. Value of this orientation can be used
+to extract the ratio of the strength of Rashba and Dresselhaus interactions.
+The spin-orbit anisotropy effects for various geometries and orientations of
+the confinement potential are discussed. Our analysis explains the physics
+behind the recent measurements performed on a gated self-assembled quantum dot
+[S. Takahashi et al. Phys. Rev. Lett. 104, 246801 (2010)].",1102.1002v2
+2011-02-22,Nodeless energy gaps of single-crystalline Ba0.68K0.32Fe2As2 as seen via 75As NMR,"We report $^{75}$As nuclear magnetic resonance studies on a very clean
+hole-doped single-crystal Ba$_{0.68}$K$_{0.32}$Fe$_{2}$As$_{2}$ ($T_{\rm
+{c}}=38.5$ K). The spin-lattice relaxation rate $1/T_{1}$ shows an exponential
+decrease below $T \simeq 0.45 T_{\rm c}$ down to $T \simeq 0.11 T_{\rm c}$,
+which indicates a fully opened energy gap. From the ratio $(T_{1})_{c} /
+(T_{1})_{a}$, where $a$ and $c$ denote the crystal directions, we find that the
+antiferromagnetic spin fluctuation is anisotropic in the spin space above
+$T_{\rm c}$. The anisotropy decreases below $T_{\rm c}$ and disappears at $T
+\rightarrow 0$. We argue that the anisotropy stems from spin-orbit coupling
+whose effect vanishes when spin-singlet electron pairs form with a nodeless
+gap.",1102.4417v2
+2011-02-23,Rectification of spin currents in spin chains,"We study spin transport in nonitinerant one-dimensional quantum spin chains.
+Motivated by possible applications in spintronics, we consider rectification
+effects in both ferromagnetic and antiferromagnetic systems. We find that the
+crucial ingredients in designing a system that displays a nonzero rectification
+current are an anisotropy in the exchange interaction of the spin chain
+combined with an offset magnetic field. For both ferromagnetic and
+antiferromagnetic systems we can exploit the gap in the excitation spectrum
+that is created by a bulk anisotropy to obtain a measurable rectification
+effect at realistic magnetic fields. For antiferromagnetic systems we also find
+that we can achieve a similar effect by introducing a magnetic impurity,
+obtained by altering two neighboring bonds in the spin Hamiltonian.",1102.4801v2
+2011-02-25,A large scale coherent magnetic field: interactions with free streaming particles and limits from the CMB,"We study a homogeneous and nearly-isotropic Universe permeated by a
+homogeneous magnetic field. Together with an isotropic fluid, the homogeneous
+magnetic field, which is the primary source of anisotropy, leads to a
+plane-symmetric Bianchi I model of the Universe. However, when free-streaming
+relativistic particles are present, they generate an anisotropic pressure which
+counteracts the one from the magnetic field such that the Universe becomes
+isotropized. We show that due to this effect, the CMB temperature anisotropy
+from a homogeneous magnetic field is significantly suppressed if the the
+neutrino masses are smaller than 0.3 eV.",1102.5235v1
+2011-02-28,Anisotropic magnetotransport of superconducting and normal state in an electron-doped Nd_{1.85}Ce_{0.15}CuO_{4-δ} single crystal,"The anisotropic properties of an optimally doped
+Nd_{1.85}Ce_{0.15}CuO_{4-\delta} single crystal have been studied both below
+and above the critical temperature Tc via the resistivity measurement in
+magnetic field H up to 12 T. By scaling the conductivity fluctuation around the
+superconducting transition, the upper critical field H_{c2}(T) has been
+determined for field parallel to the c-axis or to the basal ab-plane. The
+anisotropy factor \gamma={H_c2||ab}/{H_c2||c} is estimated to be about 8. In
+the normal state (50=<T=<180 K), the magnetoresistance (MR) basically follows
+an H^2 dependence and for H||c it is almost 10 times larger than that for
+H||ab. Comparing with hole-doped cuprates it suggests that the optimally doped
+Nd_{1.85}Ce_{0.15}CuO_{4-\delta} cuprate superconductor has a moderate
+anisotropy.",1102.5621v1
+2011-03-01,The effects of strong temperature anisotropy on the kinetic structure of collisionless slow shocks and reconnection exhausts. Part I: PIC simulations,"A 2-D Riemann problem is designed to study the development and dynamics of
+the slow shocks that are thought to form at the boundaries of reconnection
+exhausts. Simulations are carried out for varying ratios of normal magnetic
+field to the transverse upstream magnetic field (i.e., propagation angle with
+respect to the upstream magnetic field). When the angle is sufficiently
+oblique, the simulations reveal a large firehose-sense
+(P_parallel>P_perpendicular) temperature anisotropy in the downstream region,
+accompanied by a transition from a coplanar slow shock to a non-coplanar
+rotational mode. In the downstream region the firehose stability parameter
+epsilon=1-mu_0(P_parallel-P_perpendicular)/ B^2 tends to lock in to 0.25. This
+balance arises from the competition between counterstreaming ions, which drives
+epsilon down, and the scattering due to ion inertial scale waves, which are
+driven unstable by the downstream rotational wave. At very oblique propagating
+angles, 2-D turbulence also develops in the downstream region.",1103.0302v1
+2011-03-02,Anomalous Hall effect in NiPt thin films,"We study Hall effect in sputtered NixPt1-x thin films with different Ni
+concentrations. Temperature, magnetic field and angular dependencies are
+analyzed and the phase diagram of NiPt thin films is obtained. It is found that
+films with sub-critical Ni concentration exhibit cluster-glass behavior at low
+temperatures with a perpendicular magnetic anisotropy below the freezing
+temperature. Films with over-critical Ni concentration are ferromagnetic with
+parallel anisotropy. At the critical concentration the state of the film is
+strongly frustrated. Such films demonstrate canted magnetization with the easy
+axis rotating as a function of temperature. The magnetism appears via
+consecutive paramagnetic - cluster glass - ferromagnetic transitions, rather
+than a single second-order phase transition. But most remarkably, the
+extraordinary Hall effect changes sign at the critical concentration. We
+suggest that this is associated with a reconstruction of the electronic
+structure of the alloy at the normal metal - ferromagnet quantum phase
+transition.",1103.0367v2
+2011-03-02,Anisotropic Hc2 of K0.8Fe1.76Se2 determined up to 60 T,"The anisotropic upper critical field, Hc2(T), curves for K0.8Fe1.76Se2 are
+determined over a wide range of temperatures down to 1.5 K and magnetic fields
+up to 60 T. Anisotropic initial slopes of Hc2 ~ -1.4 T/K and -4.6 T/K for
+magnetic field applied along c-axis and ab-plane, respectively, were observed.
+Whereas the c-axis Hc2|c(T) increases quasi-linearly with decreasing
+temperature, the ab-plane Hc2|ab(T) shows a flattening, starting near 25 K
+above 30 T. This leads to a non-monotonic temperature dependence of the
+anisotropy parameter \gamma= Hc2|ab/Hc2|c. The anisotropy parameter is ~ 2 near
+Tc ~ 32 K and rises to a maximum \gamma ~ 3.6 around 27 K. For lower
+temperatures, \gamma decreases with T in a linear fashion, dropping to \gamma ~
+2.5 by T ~ 18 K. Despite the apparent differences between the K0.8Fe1.76Se2 and
+(Ba0.55K0.45)Fe2As2 or Ba(Fe0.926Co0.074)2As2, in terms of the magnetic state
+and proximity to an insulating state, the Hc2(T) curves are remarkably similar.",1103.0507v2
+2011-03-03,Electron correlation induced small anisotropy in iron-based superconductors,"We have investigated the electron correlation effect on the electronic
+structures and transport properties of the iron-based superconductors using the
+density functional theory (DFT) and dynamical mean field theory (DMFT). By
+considering the Fe 3d electron correlation using the DMFT, the bandwidth near
+the Fermi level is substantially suppressed compared to the conventional DFT
+calculation. Because of the different renormalization factors of each 3d
+orbital, the DMFT gives considerably reduced electrical anisotropy compared to
+the DFT results, which explains the unusually small anisotropic resistivity and
+superconducting property observed in the iron-based superconductors. We suggest
+that the electron correlation effect should be considered to explain the
+anisotropic transport properties of the general d/f valence electron system.",1103.0678v2
+2011-03-05,DDFT calibration and investigation of an anisotropic phase-field crystal model,"The anisotropic phase-field crystal model recently proposed and used by
+Prieler et al. [J. Phys.: Condens. Matter 21, 464110 (2009)] is derived from
+microscopic density functional theory for anisotropic particles with fixed
+orientation. Further its morphology diagram is explored. In particular we
+investigated the influence of anisotropy and undercooling on the process of
+nucleation and microstructure formation from atomic to the microscale. To that
+end numerical simulations were performed varying those dimensionless parameters
+which represent anisotropy and undercooling in our anisotropic phase-field
+crystal (APFC) model. The results from these numerical simulations are
+summarized in terms of a morphology diagram of the stable state phase. These
+stable phases are also investigated with respect to their kinetics and
+characteristic morphological features.",1103.1068v1
+2011-03-08,Upper critical field anisotropy in BaFe2-xCoxAs2 single crystals synthesized without flux,"The upper critical field was measured upto 12 T for three BaFe2-xCoxAs2
+single crystals with estimated Co concentrations of x = 0.082, x = 0.117 and x
+= 0.143. HC2 versus temperature was measured from temperature dependent
+resistivity, for various applied magnetic fields, H || ab and H || c. The
+[dHC2/dT]T=Tc, normalized with the corresponding TC, decreases with increasing
+Co content, for both directions. The anisotropy {\gamma} defined as HC2 || ab /
+HC2 || c shows a distinct increase with Co content, and its temperature
+dependence shows a peak close to the TC. Magneto transport measurements, in the
+spin density wave regions, showed significant negative MR for H || ab and
+positive MR of H || c in the x = 0.082 sample. The implications of these
+results are discussed.",1103.1476v1
+2011-03-10,Forward-backward elliptic anisotropy correlation in parton cascade,"A potential experimental probe, forward-backward elliptic anisotropy
+correlation ($C_{FB} $), has been proposed by Liao and Koch to distinguish the
+jet and true elliptic flow contribution to the measured elliptic flow ($v_2$)
+in relativistic heavy-ion collisions. Jet and flow fluctuation contribution to
+elliptic flow is investigated within the framework of a multi-phase transport
+model using the $C_{FB} $ probe. We found that the $C_{FB} $ correlation is
+remarkably different and is about two times of that proposed by Liao and Koch.
+It originates from the correlation between fluctuation of forward and backward
+elliptic flow at low transverse momentum, which is mainly due to the initial
+correlation between fluctuation of forward and backward eccentricity. This
+results in an amendment of the $C_{FB}$ by a term related to the correlation
+between fluctuation of forward and backward elliptic flow. Our results suggest
+that a suitable rapidity gap for $C_{FB} $ correlation studies should be around
+$\pm$ 3.5.",1103.2009v1
+2011-03-25,Quantum Gravitational Contributions to the CMB Anisotropy Spectrum,"We derive the primordial power spectrum of density fluctuations in the
+framework of quantum cosmology. For this purpose we perform a Born-Oppenheimer
+approximation to the Wheeler-DeWitt equation for an inflationary universe with
+a scalar field. In this way we first recover the scale-invariant power spectrum
+that is found as an approximation in the simplest inflationary models. We then
+obtain quantum gravitational corrections to this spectrum and discuss whether
+they lead to measurable signatures in the CMB anisotropy spectrum. The
+non-observation so far of such corrections translates into an upper bound on
+the energy scale of inflation.",1103.4967v3
+2011-03-31,"Cosmological observables, IR growth of fluctuations, and scale-dependent anisotropies","We extend semiclassical methods in inflationary cosmology that capture
+leading IR corrections to correlators. Such large IR effects can be absorbed
+into a coordinate change when examining sufficiently local observables, but not
+when comparing observations at large separation in scales, such as seen by a
+late-time observer. The analysis is facilitated by definition of a
+scale-dependent metric and physical momentum. These assist definition of
+""IR-safe"" observables seen by a post-inflationary observer, which are
+contrasted to those based on the local geometry of the reheating surface. For
+such observables, the observer's horizon provides an effective IR cutoff. IR
+growth contributes to enhanced statistical inhomogeneities/anisotropies at
+short scales, observation of which by a present day observer might be sought in
+21 cm measurements. Such IR corrections are argued to grow large for a very
+late-time observer.",1104.0002v2
+2011-04-06,Improved tunneling magnetoresistance at low temperature in manganite junctions grown by molecular beam epitaxy,"We report resistance versus magnetic field measurements for a
+La0.65Sr0.35MnO3/SrTiO3/La0.65Sr0.35MnO3 tunnel junction grown by
+molecular-beam epitaxy, that show a large field window of extremely high
+tunneling magnetoresistance (TMR) at low temperature. Scanning the in-plane
+applied field orientation through 360^/circ, the TMR shows 4-fold symmetry,
+i.e. biaxial anisotropy, aligned with the crystalline axes but not the junction
+geometrical long axis. The TMR reaches ~ 1900% at 4K, corresponding to an
+interfacial spin polarization of > 95% assuming identical interfaces. These
+results show that uniaxial anisotropy is not necessary for large TMR, and lay
+the groundwork for future improvements in TMR in manganite junctions.",1104.1072v1
+2011-04-10,Interplay of orbital and spin ordering in the iron pnictides,"A number of recent experiments exhibit electronic anisotropy in the iron
+pnictides, and there is a growing body of experimental evidence that its origin
+is related to orbital ordering in Fe d_{xz} and d_{yz} orbitals. We examine
+this problem in the parent compounds of the iron pnictides by a combination of
+ab initio band theory calculations, phenomenological Ginzburg-Landau theory of
+coupled orbital and magnetic order parameters, and a microscopic mean-field
+study of the Kugel-Khomskii model. We find that orbital ordering is sufficient
+to explain a number of key experimental observations, in particular a linear
+correlation between the orthorhombic lattice distortion and the magnetic
+ordered moment. We predict that orbital polarization should scale as a square
+of magnetic moment close to T_N. Mediated by orbital polarization, the
+effective spin-spin exchange interactions develop anisotropy in the ab-plane,
+in accord with recent neutron scattering measurements.",1104.1747v1
+2011-04-14,The Cosmic Linear Anisotropy Solving System (CLASS) II: Approximation schemes,"Boltzmann codes are used extensively by several groups for constraining
+cosmological parameters with Cosmic Microwave Background and Large Scale
+Structure data. This activity is computationally expensive, since a typical
+project requires from 10'000 to 100'000 Boltzmann code executions. The newly
+released code CLASS (Cosmic Linear Anisotropy Solving System) incorporates
+improved approximation schemes leading to a simultaneous gain in speed and
+precision. We describe here the three approximations used by CLASS for basic
+LambdaCDM models, namely: a baryon-photon tight-coupling approximation which
+can be set to first order, second order or to a compromise between the two; an
+ultra-relativistic fluid approximation which had not been implemented in public
+distributions before; and finally a radiation streaming approximation taking
+reionisation into account.",1104.2933v3
+2011-04-20,Static and dynamic properties of Single-Chain Magnets with sharp and broad domain walls,"We discuss time-quantified Monte-Carlo simulations on classical spin chains
+with uniaxial anisotropy in relation to static calculations. Depending on the
+thickness of domain walls, controlled by the relative strength of the exchange
+and magnetic anisotropy energy, we found two distinct regimes in which both the
+static and dynamic behavior are different. For broad domain walls, the
+interplay between localized excitations and spin waves turns out to be crucial
+at finite temperature. As a consequence, a different protocol should be
+followed in the experimental characterization of slow-relaxing spin chains with
+broad domain walls with respect to the usual Ising limit.",1104.4007v2
+2011-04-28,The High-Redshift Neutral Hydrogen Signature of an Anisotropic Matter Power Spectrum,"An anisotropic power spectrum will have a clear signature in the 21cm
+radiation from high-redshift hydrogen. We calculate the expected power spectrum
+of the intensity fluctuations in neutral hydrogen from before the epoch of
+reionization, and predict the accuracy to which future experiments could
+constrain a quadrupole anisotropy in the power spectrum. We find that the
+Square Kilometer Array will have marginal detection abilities for this signal
+at z~17 if the process of reionization has not yet started; reionization could
+enhance the detectability substantially. Pushing to higher redshifts and higher
+sensitivity will allow highly precise (percent level) measurements of
+anisotropy.",1104.5403v3
+2011-04-29,Upper critical magnetic field in Ba_0.68K_0.32Fe_2As_2 and Ba(Fe_0.93Co_0.07)_2As_2,"We report measurements of the temperature dependence of the radio-frequency
+magnetic penetration depth in Ba_0.68K_0.32Fe_2As_2 and
+Ba(Fe_0.93Co_0.07)_2As_2 single crystals in pulsed magnetic fields up to 60 T.
+From our data, we construct an H-T phase diagram for the inter-plane (H || c)
+and in-plane (H || ab) directions for both compounds. For both field
+orientations in Ba_0.68K_0.32Fe_2As_2, we find a concave curvature of the
+Hc2(T) lines with decreasing anisotropy and saturation towards lower
+temperature. Taking into account Pauli spin paramagnetism we can describe
+Hc2(T) and its anisotropy. In contrast, we find that Pauli paramagnetic pair
+breaking is not essential for Ba(Fe_0.93Co_0.07)_2As_2. For this electron-doped
+compound, the data support a Hc2(T) dependence that can be described by the
+Werthamer Helfand Hohenberg model for H || ab and a two-gap behavior for H ||
+c.",1104.5619v1
+2011-05-05,Antiferromagnet with two coupled antiferromagnetic sublattices in a magnetic field,"We discuss the magnon spectrum of an antiferromagnet (AF) in a magnetic field
+$h$ consisting of two interpenetrating AF sublattices coupled by the exchange
+interaction at T=0. One-ion easy-plane anisotropy is also taken into account.
+We calculate using the 1/S expansion the gap in the spectrum which is a
+manifestation of the order-by-disorder effect in this system and the optical
+magnon mode splitting. Both of these phenomena originate from the
+inter-sublattice interaction. We calculate also the gap value at $h\approx h_c$
+in the leading order of the small parameter $(h_c-h)/h_c$ using the magnon
+Bose-Einstein condensation treatment, where $h_c$ is the saturation field. By
+comparing results obtained within these two approaches we conclude that the 1/S
+expansion gives a qualitatively correct result at $h\sim h_c$ even at large
+one-ion anisotropy but it overestimates the gap value. The application is
+discussed of these results to the actively studied AF of the considered type
+$\rm NiCl_2$-$\rm 4SC(NH_2)_2$ (DTN).",1105.1044v1
+2011-05-05,Novel approach to description of quantum magnets with large singe-ion easy-plane anisotropy,"We introduce a new representation of an integer spin $S$ via bosonic
+operators which is useful in describing the paramagnetic phase and transitions
+to magnetically ordered phases in magnetic systems with large single-ion
+easy-plane anisotropy $D$. Considering the exchange interaction between spins
+as a perturbation and using the diagram technique we derive the elementary
+excitation spectrum and the ground state energy in the third order of the
+perturbation theory. In the special case of S=1 we obtain these expressions
+also using simpler spin representations some of which were introduced before.
+Comparison with results of previous numerical studies of 2D systems with S=1
+demonstrates that our approach works better than other analytical methods
+applied before for such systems. We apply our results for the elementary
+excitation spectrum analysis obtained experimentally in $\rm NiCl_2$-$\rm
+4SC(NH_2)_2$ (DTN). It is demonstrated that a set of model parameters (exchange
+constants and $D$) which has been used for DTN so far describes badly the
+experimentally obtained spectrum. A new set of parameters is proposed using
+which we fit the spectrum and values of two critical fields of DTN.",1105.1077v1
+2011-05-12,First-Order Phase Transition with Breaking of Lattice Rotation Symmetry in Continuous-Spin Model on Triangular Lattice,"Using a Monte Carlo method, we study the finite-temperature phase transition
+in the two-dimensional classical Heisenberg model on a triangular lattice with
+or without easy-plane anisotropy. The model takes account of competing
+interactions: a ferromagnetic nearest-neighbor interaction $J_1$ and an
+antiferromagnetic third nearest-neighbor interaction $J_3$. As a result, the
+ground state is a spiral spin configuration for $-4 < J_1/J_3 < 0$. In this
+structure, global spin rotation cannot compensate for the effect of 120-degree
+lattice rotation, in contrast to the conventional 120-degree structure of the
+nearest-neighbor interaction model. We find that this model exhibits a
+first-order phase transition with breaking of the lattice rotation symmetry at
+a finite temperature. The transition is characterized as a $Z_2$ vortex
+dissociation in the isotropic case, whereas it can be viewed as a $Z$ vortex
+dissociation in the anisotropic case. Remarkably, the latter is continuously
+connected to the former as the magnitude of anisotropy decreases, in contrast
+to the recent work by Misawa and Motome [J. Phys. Soc. Jpn. \textbf{79} (2010)
+073001.] in which both the transitions were found to be continuous.",1105.2452v2
+2011-05-22,The strong side of weak topological insulators,"Three-dimensional topological insulators are classified into ""strong"" (STI)
+and ""weak"" (WTI) according to the nature of their surface states. While the
+surface states of the STI are topologically protected from localization, this
+does not hold for the WTI. In this work we show that the surface states of the
+WTI are actually protected from any random perturbation that does not break
+time-reversal symmetry, and does not close the bulk energy gap. Consequently,
+the conductivity of metallic surfaces in the clean system remains finite even
+in the presence of strong disorder of this type. In the weak disorder limit the
+surfaces are found to be perfect metals, and strong surface disorder only acts
+to push the metallic surfaces inwards. We find that the WTI differs from the
+STI primarily in its anisotropy, and that the anisotropy is not a sign of its
+weakness but rather of its richness.",1105.4351v2
+2011-05-24,Effect of Polydispersity and Anisotropy in Colloidal and Protein Solutions: an Integral Equation Approach,"Application of integral equation theory to complex fluids is reviewed, with
+particular emphasis to the effects of polydispersity and anisotropy on their
+structural and thermodynamic properties. Both analytical and numerical
+solutions of integral equations are discussed within the context of a set of
+minimal potential models that have been widely used in the literature. While
+other popular theoretical tools, such as numerical simulations and density
+functional theory, are superior for quantitative and accurate predictions, we
+argue that integral equation theory still provides, as in simple fluids, an
+invaluable technique that is able to capture the main essential features of a
+complex system, at a much lower computational cost. In addition, it can provide
+a detailed description of the angular dependence in arbitrary frame, unlike
+numerical simulations where this information is frequently hampered by
+insufficient statistics. Applications to colloidal mixtures, globular proteins
+and patchy colloids are discussed, within a unified framework.",1105.4723v1
+2011-05-25,On the magnetization textures in NiPd nanostructures,"We have observed peculiar magnetization textures in Ni$_{80}$Pd$_{20}$
+nanostructures using three different imaging techniques: magnetic force
+microscopy, photoemission electron microscopy under polarized X-ray absorption,
+and scanning electron microscopy with polarization analysis. The appearances of
+diamond-like domains with strong lateral charges and of weak stripe structures
+bring into evidence the presence of both a transverse and a perpendicular
+anisotropy in these nanostrips. This anisotropy is seen to reinforce as
+temperature decreases, as testified by a simplified domain structure at 150 K.
+A thermal stress relaxation model is proposed to account for these
+observations. Elastic calculations coupled to micromagnetic simulations support
+qualitatively this model.",1105.4946v1
+2011-05-27,Gluon dissociation of $J/ψ$ in anisotropic {\em Quark-Gluon-Plasma},"We calculate the gluon dissociation cross-section in an anisotropic quark
+gluon plasma expected to be formed due relativistic nucleus-nucleus collisions.
+The initial rapid longitudinal expansion of the system leads to momentum space
+anisotropy due which the observables are affected in such a system. We show
+that the thermally weighted cross-section of gluon dissociation undergoes
+modification in anisotropic plasma leading to a decreased probability of
+$J/\psi$ suppression both for RHIC and LHC energies. The dependence of the
+cross section as well as the survival probability on the direction of
+propagation of the charmonium with respect to the anisotropy axis are
+presented. The sensitivity of the survival probability on the initial
+conditions have also been demonstrated.",1105.5528v2
+2011-05-31,Universal and non-universal amplitude ratios for scaling corrections on Ising strips,"We consider strips of Ising spins at criticality. For strips of width $N$
+sites, subdominant (additive) finite-size corrections to scaling are assumed to
+be of the form $a_k/N^k$ for the free energy, and $b_k/N^k$ for inverse
+correlation length, with integer values of $k$. We investigate the set
+$\{a_k,b_k\}$ ($k \geq 2$) by exact evaluation and numerical transfer-matrix
+diagonalization techniques, and their changes upon varying anisotropy of
+couplings, spin quantum number $S$, and (finite) interaction range, in all
+cases for both periodic (PBC) and free (FBC) boundary conditions across the
+strip. We find that the coefficient ratios $b_k/a_k$ remain constant upon
+varying coupling anisotropy for $S=1/2$ and first-neighbor couplings, for both
+PBC and FBC (albeit at distinct values in either case). Such universal behavior
+is not maintained upon changes in $S$ or interaction range.",1105.6248v2
+2011-06-01,Beyond the Standard cosmological model with CMB,"Measurements of CMB anisotropy and, more recently, polarization have played a
+very important role in cosmology. Besides precise determination of various
+parameters of the `standard' cosmological model, observations have also
+established some important basic tenets that underlie models of cosmology and
+structure formation in the universe -- `acausally' correlated, adiabatic,
+primordial perturbations in a flat, statistically isotropic universe. These are
+consistent with the expectation of the paradigm of inflation and the generic
+prediction of the simplest realization of inflationary scenario in the early
+universe. Further, gravitational instability is the established mechanism for
+structure formation from these initial perturbations. Primordial perturbations
+observed as the CMB anisotropy and polarization is the most compelling evidence
+for new, possibly fundamental, physics in the early universe. The community is
+now looking beyond the parameter estimation of the `standard' model, for
+subtle, characteristic signatures of early universe physics.",1106.0106v1
+2011-06-10,Non Axi-symmetric Anisotropy of Solar Wind Turbulence,"A key prediction of turbulence theories is frame-invariance, and in
+magnetohydrodynamic (MHD) turbulence, axisymmetry of fluctuations with respect
+to the background magnetic field. Paradoxically the power in fluctuations in
+the turbulent solar wind are observed to be ordered with respect to the bulk
+macroscopic flow as well as the background magnetic field. Here, non-
+axisymmetry across the inertial and dissipation ranges is quantified using
+in-situ observations from Cluster. The observed inertial range non- axisymmetry
+is reproduced by a 'fly through' sampling of a Direct Numerical Simulation of
+MHD turbulence. Furthermore, 'fly through' sampling of a linear superposition
+of transverse waves with axisymmetric fluctuations generates the trend in non-
+axisymmetry with power spectral exponent. The observed non-axisymmetric
+anisotropy may thus simply arise as a sampling effect related to Taylor's
+hypothesis and is not related to the plasma dynamics itself.",1106.2023v2
+2011-06-14,Fine structure constant variation or spacetime anisotropy?,"Recent observations on the quasar absorption spectra supply evidence for the
+variation of the fine structure constant $\alpha$. In this paper, we propose
+another interpretation of the observational data on the quasar absorption
+spectra: a scenario with spacetime inhomogeneity and anisotropy. Maybe the
+spacetime is characterized by the Finsler geometry instead of the Riemann one.
+The Finsler geometry admits fewer symmetries than the Riemann geometry does. We
+investigate the Finslerian geodesic equations in the Randers spacetime (a
+special Finsler spacetime). It is found that the cosmological redshift in this
+spacetime deviates from the one in general relativity. The modification term to
+the redshift could be generally revealed as a monopole plus dipole function of
+spacetime locations and directions. We suggest that this modification
+corresponds to the spatial monopole and dipole of $\alpha$ variation in the
+quasar absorption spectra.",1106.2726v3
+2011-06-16,Tunable multi-photon Rabi oscillations in an electronic spin system,"We report on multi-photon Rabi oscillations and controlled tuning of a
+multi-level system at room temperature (S=5/2 for Mn2+:MgO) in and out of a
+quasi-harmonic level configuration. The anisotropy is much smaller than the
+Zeeman splittings, such as the six level scheme shows only a small deviation
+from an equidistant diagram. This allows us to tune the spin dynamics by either
+compensating the cubic anisotropy with a precise static field orientation, or
+by microwave field intensity. Using the rotating frame approximation, the
+experiments are very well explained by both an analytical model and a
+generalized numerical model. The calculated multi-photon Rabi frequencies are
+in excellent agreement with the experimental data.",1106.3365v1
+2011-06-21,Probing Cosmic Acceleration by Using the SNLS3 SNIa Dataset,"We probe the cosmic acceleration by using the recently released SNLS3 sample
+of 472 type Ia supernovae. Combining this type Ia supernovae dataset with the
+cosmic microwave background anisotropy data from the Wilkinson Microwave
+Anisotropy Probe 7-yr observations, the baryon acoustic oscillation results
+from the Sloan Digital Sky Survey data release 7, and the Hubble constant
+measurement from the Wide Field Camera 3 on the Hubble Space Telescope, we
+measure the dark energy equation of state $w$ and the deceleration parameter
+$q$ as functions of redshift by using the Chevallier-Polarski-Linder
+parametrization. Our result is consistent with a cosmological constant at
+1$\sigma$ confidence level, without evidence for the recent slowing down of the
+cosmic acceleration. Furthermore, we consider three binned parametrizations
+($w$ is piecewise constant in redshift $z$) based on different binning methods.
+The similar results are obtained, i.e., the $\Lambda$CDM model is still nicely
+compatible with current observations.",1106.4116v3
+2011-06-27,Phase transitions and entanglement properties in spin-1 Heisenberg clusters with single-ion anisotropy,"The incipient quantum phase transitions of relevance to nonzero fluctuations
+and entanglement in Heisenberg clusters are studied in this paper by exploiting
+negativity as a measure in bipartite and frustrated spin-1 anisotropic
+Heisenberg clusters with bilinear-biquadratic exchange, single-ion anisotropy
+and magnetic field. Using the exact diagonalization technique, it is shown that
+quantum critical points signaled by qualitative changes in behavior of
+magnetization and particle number are ultimately related to microscopic
+entanglement and collective excitations. The plateaus and peaks in spin and
+particle susceptibilities define the conditions for a high/low-density quantum
+entanglement and various ordered phases with different spin (particle)
+concentrations.",1106.5378v1
+2011-06-27,The Ising Limit of the XXZ Heisenberg Magnet and Certain Thermal Correlation Functions,"The spin-1/2 XXZ Heisenberg magnet is considered for the case of the
+anisotropy parameter tending to infinity (so-called, Ising limit). A thermal
+correlation function of the ferromagnetic string is calculated over the ground
+state. The approach to the calculation of the correlation functions in the
+limit of infinite anisotropy is based on the observation that the wave function
+is expressed in terms of the symmetric Schur functions. It is demonstrated that
+at low temperatures the amplitude of the asymptotical expression of this
+correlation function is proportional to the squared numbers of strict boxed
+plane partitions.",1106.5455v2
+2011-06-29,Apparent temperature anisotropies due to wave activity in the solar wind,"The fast solar wind is a collisionless plasma permeated by plasma waves on
+many different scales. A plasma wave represents the natural interplay between
+the periodic changes of the electromagnetic field and the associated coherent
+motions of the plasma particles. In this paper, a model velocity distribution
+function is derived for a plasma in a single, coherent, large-amplitude wave.
+This model allows one to study the kinetic effects of wave motions on particle
+distributions. They are by in-situ spacecraft measured by counting, over a
+certain sampling time, the particles coming from various directions and having
+different energies. We compare our results with the measurements by the Helios
+spacecraft, and thus find that by assuming high wave activity we are able to
+explain key observed features of the measured distributions within the
+framework of our model. We also address the recent discussions on nonresonant
+wave--particle interactions and apparent heating. The applied time-averaging
+procedure leads to an apparent ion temperature anisotropy which is connected
+but not identical to the intrinsic temperature of the underlying distribution
+function.",1106.5878v1
+2011-06-29,Image denoising assessment using anisotropic stack filtering,"In this paper we propose a measure of anisotropy as a quality parameter to
+estimate the amount of noise in noisy images. The anisotropy of an image can be
+determined through a directional measure, using an appropriate statistical
+distribution of the information contained in the image. This new measure is
+achieved through a stack filtering paradigm. First, we define a local
+directional entropy, based on the distribution of 0's and 1's in the
+neigborhood of every pixel location of each stack level. Then the entropy
+variation of this directional entropy is used to define an anisotropic measure.
+The empirical results have shown that this measure can be regarded as an
+excellent image noise indicator, which is particularly relevant for quality
+assessment of denoising algorithms. The method has been evaluated with
+artificial and real-world degraded images.",1106.5928v1
+2011-07-01,Accurate determination of the Gaussian transition in spin-1 chains with single-ion anisotropy,"The Gaussian transition in the spin-one Heisenberg chain with single-ion
+anisotropy is extremely difficult to treat, both analytically and numerically.
+We introduce an improved DMRG procedure with strict error control, which we use
+to access very large systems. By considering the bulk entropy, we determine the
+Gaussian transition point to 4-digit accuracy, $D_{c}/J
+  = 0.96845(8)$, resolving a long-standing debate in quantum magnetism. With
+this value, we obtain high-precision data for the critical behavior of
+quantities including the ground-state energy, gap, and transverse string-order
+parameter, and for the critical exponent, $\nu = 1.472(2)$. Applying our
+improved technique at $J_{z} = 0.5$ highlights essential differences in
+critical behavior along the Gaussian transition line.",1107.0229v2
+2011-07-02,Energy dissipation and switching delay in spin-transfer torque switching of nanomagnets with low-saturation magnetization in the presence of thermal fluctuations,"A common ploy to reduce the switching current and energy dissipation in
+spin-transfer-torque driven magnetization switching of shape-anisotropic
+single-domain nanomagnets is to employ magnets with low saturation
+magnetization $M_s$ and high shape-anisotropy. The high shape-anisotropy
+compensates for low $M_s$ to keep the static switching error rate constant.
+However, this ploy increases the switching delay, its variance in the presence
+of thermal noise, and the dynamic switching error rate. Using the stochastic
+Landau-Lifshitz-Gilbert equation with a random torque emulating thermal noise,
+we show that pumping some excess spin-polarized current into the nanomagnet
+during switching will keep the mean switching delay and its variance constant
+as we reduce $M_s$, while still reducing the energy dissipation significantly.",1107.0387v2
+2011-07-06,Dynamical vs spectator models of (pseudo-)conformal Universe,"We discuss two versions of the conformal scenario for generating scalar
+cosmological perturbations: a spectator version with a scalar field conformally
+coupled to gravity and carrying negligible energy density, and a dynamical
+version with a scalar field minimally coupled to gravity and dominating the
+cosmological evolution. By making use of the Newtonian gauge, we show that (i)
+no UV strong coupling scale is generated below $M_{Pl}$ due to mixing with
+metric perturbations in the dynamical scenario, and (ii) the dynamical and
+spectator models yield identical results to the leading non-linear order. We
+argue that these results, which include potentially observable effects like
+statistical anisotropy and non-Gaussianity, are characteristic of the entire
+class of conformal models. As an example, we reproduce, within the dynamical
+scenario and working in comoving gauge, our earlier result on the statistical
+anisotropy, which was originally obtained within the spectator approach.",1107.1036v1
+2011-07-11,Impairment of double exchange mechanism in electron transport of iron pnictides,"Double exchange mechanism is believed to favor transport along ferromagnetic
+directions, the failure of which in explaining the unusual resistivity
+anisotropy in iron pnictides is investigated. Several factors intrinsic to the
+microscopic mechanism of transport in iron pnictides are identified and
+analyzed, including the moderate Hund's coupling, low local moment, and
+presence of two anisotropic degenerate orbitals xz and yz. In particular, the
+substantial second neighbor hoppings are found to be decisive in giving results
+opposite to the double exchange picture. In high temperature nonmagnetic phase,
+orbital ordering is shown to give the right trend of resistivity anisotropy as
+observed experimentally, advocating its essential role in electron transport of
+iron pnictides.",1107.1952v1
+2011-07-14,Statistical Anisotropy and the Vector Curvaton Paradigm,"The vector curvaton paradigm is reviewed. The mechanism allows a massive
+vector boson field to contribute to or even generate the curvature perturbation
+in the Universe. Contribution of vector bosons is likely to generate
+statistical anisotropy in the spectrum and bispectrum of the curvature
+perturbation, which will soon be probed observationally. Two specific models
+for the generation of superhorizon spectra for the components of an Abelian
+vector field are analysed. Emphasis is put on the observational signatures of
+the models when the vector fields play the role of vector curvatons. If future
+observations support the vector curvaton mechanism this will open a window into
+the gauge field content of theories beyond the standard model.",1107.2779v2
+2011-07-19,Spin-texture and magnetic anisotropy of Co adsorbed Bi$_2$Se$_3$ topological insulator surfaces,"Based upon first-principles methods, we investigate the magnetic anisotropy
+and the spin-texture of Co adatoms embedded in the topmost Se network of the
+topological insulator Bi$_2$Se$_3$ surface. We find the formation of
+energetically stable magnetic moment perpendicular to the surface plane, S$_z$.
+Our results for the pristine Bi$_2$Se$_3$ surface indicate the presence of
+helical spin-texture not only in the massless surface Dirac states, but also
+surface states resonant within the valence band present spin-texture. On the
+other hand, upon the presence of Co adatoms we find that the out-of-plane
+surface magnetism represents the dominant spin state (S$_z$), while the planar
+spin components, S$_x$ and S$_y$, are almost suppressed.",1107.3810v1
+2011-07-20,"Peculiar motions, accelerated expansion and the cosmological axis","Peculiar velocities change the expansion rate of any observer moving relative
+to the smooth Hubble flow. As a result, observers in a galaxy like our Milky
+Way can experience accelerated expansion within a globally decelerating
+universe, even when the drift velocities are small. The effect is local, but
+the affected scales can be large enough to give the false impression that the
+whole cosmos has recently entered an accelerating phase. Generally, peculiar
+velocities are also associated with dipole-like anisotropies, triggered by the
+fact that they introduce a preferred spatial direction. This implies that
+observers experiencing locally accelerated expansion, as a result of their own
+drift motion, may also find that the acceleration is maximised in one direction
+and minimised in the opposite. We argue that, typically, such a dipole
+anisotropy should be relatively small and the axis should probably lie fairly
+close to the one seen in the spectrum of the Cosmic Microwave Background.",1107.4045v3
+2011-07-22,"Large spin-phonon coupling and magnetically-induced phonon anisotropy in Sr$M$O$_3$ perovskites ($M$=V,Cr,Mn,Fe,Co)","First-principles calculations reveal large zone-center spin-phonon coupling
+and magnetically-driven phonon anisotropy in cubic perovskites Sr$M$O$_3$
+($M$=V,Cr,Mn,Fe,Co). In particular, the frequency and splitting of the polar
+Slater mode is found to depend strongly on magnetic ordering. The coupling is
+parameterized in a crystal-structure-dependent Heisenberg model and its main
+features seen to arise from the Goodenough-Kanamori rules. This coupling can be
+expected to produce distinct low-energy alternative phases, resulting in a rich
+variety of coupled magnetic, structural and electronic phase transitions driven
+by temperature, stress, electric field and cation substitution.",1107.4405v1
+2011-07-25,Thermalization in Weakly Coupled Nonabelian Plasmas,"We investigate how relativistic, nonabelian plasmas approach equilibrium in a
+general context. Our treatment is entirely parametric and for small Yang-Mills
+coupling $\alpha$. First we study isotropic systems with an initially
+nonequilibrium momentum distribution. We consider both the case of initially
+very high occupancy and initially very low occupancy. Then we consider systems
+which are anisotropic. We consider both weak anisotropy and large anisotropy,
+and allow the occupancy to be parametrically large or small. Writing the
+typical momentum of an initial excitation as Q and the final temperature as T,
+full equilibration occurs in a time t ~ \alpha^{-2}/T for T > Q, and t ~
+\alpha^{-2} Q^{1/2} T^{-3/2} for T < Q, unless the initial system is
+sufficiently anisotropic and T > \alpha^{2/3} Q, in which case equilibration
+occurs somewhat faster, t ~ \alpha^{-13/7} Q^{5/7} T^{-12/7} (or \alpha^{-2}/T
+if that is longer).",1107.5050v1
+2011-07-27,Understanding anisotropy generated by fluctuations in heavy-ion collisions,"Event-by-event fluctuations are central to the current understanding of
+ultrarelativistic heavy-ion collisions. In particular, fluctuations in the
+geometry of the early-time collision system are responsible for new phenomena
+such as triangular flow, which have solved important puzzles in existing data.
+We propose a simple model where initial fluctuations stem from independent flux
+tubes randomly distributed in the transverse plane. We calculate analytically
+the moments of the initial anisotropies (dipole asymmetry, eccentricity,
+triangularity), which are the sources of anisotropic flow, and their mutual
+correlations. Our analytic results are in good agreement with calculations from
+commonly-used Monte-Carlo codes, providing a simple understanding of the
+fluctuations contained in these models. Any deviation from these results in
+future experimental data would thus indicate the presence of non-trivial
+correlations between the initial flux tubes and/or extra sources of
+fluctuations that are not present in current models.",1107.5485v2
+2011-07-27,The effects of plasma beta and anisotropy instabilities on the dynamics of reconnecting magnetic fields in the heliosheath,"The plasma {\beta} (the ratio of the plasma pressure to the magnetic
+pressure) of a system can have a large effect on its dynamics as high {\beta}
+enhances the effects of pressure anisotropies. We investigate the effects of
+{\beta} in a system of stacked current sheets that break up into magnetic
+islands due to magnetic reconnection. We find significant differences between
+{\beta} < 1 and {\beta} > 1. At low {\beta} growing magnetic islands are
+modestly elongated and become round as contraction releases magnetic stress and
+reduces magnetic energy. At high {\beta} the increase of the parallel pressure
+in contracting islands causes saturation of modestly elongated islands as
+island cores approach the marginal firehose condition. Only highly elongated
+islands reach finite size. The kinking associated with the Weibel and firehose
+instabilities prevents full contraction of these islands, leading to a final
+state of highly elongated islands in which further reconnection is suppressed.
+The results are directly relevant to reconnection in the sectored region of the
+heliosheath and possibly to saturation mechanisms of the magnetorotational
+instability in accretion flows.",1107.5558v2
+2011-08-01,Correlation energy of anisotropic quantum dots,"We study the $D$-dimensional high-density correlation energy $\Ec$ of the
+singlet ground state of two electrons confined by a harmonic potential with
+Coulombic repulsion. We allow the harmonic potential to be anisotropic, and
+examine the behavior of $\Ec$ as a function of the anisotropy $\alpha^{-1}$. In
+particular, we are interested in the limit where the anisotropy goes to
+infinity ($\alpha\to0$) and the electrons are restricted to a lower-dimensional
+space. We show that tuning the value of $\alpha$ from 0 to 1 allows a smooth
+dimensional interpolation and we demonstrate that the usual model, in which a
+quantum dot is treated as a two-dimensional system, is inappropriate. Finally,
+we provide a simple function which reproduces the behavior of $\Ec$ over the
+entire range of $\alpha$.",1108.0257v1
+2011-08-05,Influence of strain on anisotropic thermoelectric transport of Bi$_2$Te$_3$ and Sb$_2$Te$_3$,"On the basis of detailed first-principles calculations and semi-classical
+Boltzmann transport, the anisotropic thermoelectric transport properties of
+Bi$_2$Te$_3$ and Sb$_2$Te$_3$ under strain were investigated. It was found that
+due to compensation effects of the strain dependent thermopower and electrical
+conductivity, the related powerfactor will decrease under applied in-plane
+strain for Bi$_2$Te$_3, while being stable for Sb$_2$Te$_3$. A clear preference
+for thermoelectric transport under hole-doping, as well as for the in-plane
+transport direction was found for both tellurides. In contrast to the
+electrical conductivity anisotropy, the anisotropy of the thermopower was
+almost robust under applied strain. The assumption of an anisotropic relaxation
+time for Bi$_2$Te$_3$ suggests, that already in the single crystalline system
+strong anisotropic scattering effects should play a role.",1108.1304v2
+2011-08-05,Role of Antisymmetric Exchange in Selecting Magnetic Chirality in Ba$_3$NbFe$_3$Si$_2$O$_{14}$,"We present electron spin resonance (ESR) investigation of the acentric
+\FeLang, featuring a unique single-domain double-chiral magnetic ground state.
+Combining simulations of the ESR line-width anisotropy and the
+antiferromagnetic-resonance modes allows us to single out the
+Dzyaloshinsky-Moriya (DM) interaction as the leading magnetic anisotropy term.
+We demonstrate that the rather minute out-of-plane DM component $d_c=45$ mK is
+responsible for selecting a unique ground state, which endures thermal
+fluctuations up to astonishingly high temperatures.",1108.1390v2
+2011-08-08,Anisotropy effects on Rashba and topological insulator spin polarized surface states: a unified phenomenological description,"Spin polarized two-dimensional electronic states have been previously
+observed on metallic surface alloys with giant Rashba splitting and on the
+surface of topological insulators. We study the surface band structure of these
+systems, in a unified manner, by exploiting recent results of k.p theory. The
+model suggests a different way to address the effect of anisotropy in Rashba
+systems. Changes in the surface band structure of various Rashba compounds can
+be captured by a single effective parameter which quantifies the competition
+between the Rashba effect and the hexagonal warping of the constant energy
+contours. The same model provides a unified phenomenological description of the
+surface states belonging to materials with topologically trivial and
+non-trivial band structures.",1108.1778v3
+2011-08-10,Origin of Ultrahigh Energy Galactic Cosmic Rays: The Isotropy Problem,"We study the propagation of ultra-high-energy cosmic rays (UHECR) in the
+Galaxy, concentrating on the energy range below the ankle in the spectrum at 4
+EeV. A Monte-Carlo method, based on analytical solutions to the time-dependent
+diffusion problem, is used to account for intermittency by placing sources at
+random locations. Assuming a source population that scales with baryon mass
+density or star formation (e.g. long GRB), we derive constraints arising from
+intermittency and the observational limits on the composition and anisotropy.
+It is shown that the composition and anisotropy at 1e18 eV are difficult to
+reproduce and require that either a) the particle mean free path is much
+smaller than a gyroradius, implying the escape time is very long, b) the
+composition is heavier than suggested by recent Auger data, c) the
+ultrahigh-energy sub-ankle component is mostly extragalactic, or d) we are
+living in a rare lull in the ultrahigh-energy cosmic-ray production, and the
+current ultrahigh-energy cosmic-ray intensity is far below the Galactic time
+average. We therefore recommend a strong observational focus on determining the
+UHECR composition around 1e18 eV.",1108.2135v2
+2011-08-11,"Radiation pressure dominant acceleration: polarization and radiation reaction effects, and energy increase in three-dimensional simulations","Polarization and radiation reaction (RR) effects in the interaction of a
+superintense laser pulse (I > 10^23 W/cm^2) with a thin plasma foil are
+investigated with three dimensional particle-in-cell (PIC) simulations. For a
+linearly polarized laser pulse, strong anisotropies such as the formation of
+two high-energy clumps in the plane perpendicular to the propagation direction
+and significant radiation reactions effects are observed. On the contrary,
+neither anisotropies nor significant radiation reaction effects are observed
+using circularly polarized laser pulses, for which the maximum ion energy
+exceeds the value obtained in simulations of lower dimensionality. The
+dynamical bending of the initially flat plasma foil leads to the self-formation
+of a quasi-parabolic shell that focuses the impinging laser pulse strongly
+increasing its energy and momentum densities.",1108.2372v3
+2011-08-11,Entanglement Perturbation Theory for Infinite Quasi-1D Quantum Systems,"We develop Entanglement Perturbation Theory (EPT) for infinite Quasi-1D
+quantum systems. The spin 1/2 Heisenberg chain with ferromagnetic nearest
+neighbor (NN) and antiferromagnetic next nearest neighbor (NNN) interactions
+with an easy-plane anisotropy is studied as a prototypical system. The obtained
+accurate phase diagram is compared with a recent prediction
+[Phys.Rev.B,81,094430(2010)] that dimer and Neel orders appear alternately as
+the XXZ anisotropy Delta approaches the isotropic limit Delta=1. The first and
+second transitions (across dimer, Neel, and dimer phases) are detected with
+improved accuracy at Delta\approx 0.722 and 0.930. The third transition (from
+dimer to Neel phases), previously predicted to be at Delta\approx 0.98, is not
+detected at this Delta in our method, raising the possibility that the second
+Neel phase is absent.",1108.2532v3
+2011-08-13,Phononic Self energy effects and superconductivity in CaC$_6$,"We study the graphite intercalated compound CaC$_6$ by means of Eliashberg
+theory, focusing on the anisotropy properties. An analysis of the
+electron-phonon coupling is performed, and we define a minimal 6-band
+anisotropy structure. Comparing with Superconducting Density Functional Theory
+(SCDFT) the condition under which Eliashberg theory is able to reproduce the
+SCDFT gap structure is determined, and we discuss the role of Coulomb
+interactions. The Engelsberg-Schrieffer polaron structure is computed by
+solving the Eliashberg equation on the Matsubara axis and analytically
+continuing it to the full complex plane. This reveals the polaronic
+quasiparticle bands anisotropic features as well as the interplay with
+superconductivity.",1108.2800v2
+2011-08-18,Large scale anisotropy due to pre-inflationary phase of cosmic evolution,"We show that perturbations generated during the anisotropic pre-inflationary
+stage of cosmic evolution may affect cosmological observations today for a
+certain range of parameters. Due to the anisotropic nature of the universe
+during such early times, it might explain some of the observed signals of large
+scale anisotropy. In particular we argue that the alignment of CMB quadrupole
+and octopole may be explained by the Sachs-Wolfe effect due to the large scale
+anisotropic modes from very early times of cosmological evolution. We also
+comment on how the observed dipole modulation of CMB power may be explained
+within this framework.",1108.3643v2
+2011-08-22,Statistical Anisotropy from Vector Curvaton in D-brane Inflation,"We investigate the possibility of embedding the vector curvaton paradigm in
+D-brane models of inflation in Type IIB string theory in a simple toy model.
+The vector curvaton is identified with the U(1) gauge field that lives on the
+world volume of a D3-brane, which may be stationary or undergoing general
+motion in the internal space. The dilaton is considered as a spectator field
+which modulates the evolution of the vector field. In this set up, the vector
+curvaton is able to generate measurable statistical anisotropy in the spectrum
+and bispectrum of the curvature perturbation assuming that the dilaton evolves
+as e^(-\phi)\propto a^2 where a(t) is the scale factor. Our work constitutes a
+first step towards exploring how such distinctive features may arise from the
+presence of several light fields that naturally appear in string theory models
+of cosmology.",1108.4424v3
+2011-08-30,Molecular dynamics simulation for heat transport in thin diamond nanowires,"The phonon thermal conductivity in diamond nanowires (DNW) is studied by
+molecular dynamics simulation. It is found that the thermal conductivity in
+narrower DNW is lower and does not show obvious temperature dependence; a very
+small value (about 2.0 W/m/K) of thermal conductivity is observed in
+ultra-narrow DNW, which may be of potential applications in thermoelectric
+devices. These two phenomena are probably due to the dominant surface effect
+and phonon confinement effect in narrow DNW. Our simulation reveals a high
+anisotropy in the heat transport of DNW. Specifically, the thermal conductivity
+in DNW along [110] growth direction is about five times larger than that of
+[100] and [111] growth directions. The anisotropy is believed to root in the
+anisotropic group velocity for acoustic phonon modes in DNW along three
+different growth directions.",1108.5812v1
+2011-08-30,Direct measurement of the angular power spectrum of cosmic microwave background temperature anisotropies in the WMAP Data,"Angular power spectrum of the cosmic microwave background (CMB) temperature
+anisotropies is one of the most important on characteristics of the Universe
+such as its geometry and total density. Using flat sky approximation and
+Fourier analysis, we estimate the angular power spectrum from an ensemble of
+least foreground-contaminated square patches from WMAP W and V frequency band
+map. This method circumvents the issue of foreground cleaning and that of
+breaking orthogonality in spherical harmonic analysis due to masking out the
+bright Galactic plane region, thereby rendering a direct measurement of the
+angular power spectrum. We test and confirm Gaussian statistical characteristic
+of the selected patches, from which the first and second acoustic peak of the
+power spectrum are reproduced, and the third peak is clearly visible albeit
+with some noise residual at the tail.",1108.5824v1
+2011-09-06,Anisotropic magnetic deflagration in single crystals of Gd5Ge4,"Experimental evidence of the anisotropy of the magnetic deflagration
+associated with the low-temperature first order antiferromagnetic (AFM) -->
+ferromagnetic (FM) phase-transition in single crystals of Gd5Ge4 is reported.
+The deflagrations have been induced by controlled pulses of surface acoustic
+waves (SAW) allowing us to explore both the magnetic field and temperature
+dependencies on the characteristic times of the phenomenon. The study was done
+using samples with different geometries and configurations between the SAW
+pulses and the direction of the applied magnetic field with respect to the
+three main crystallographic directions of the samples. The effect of
+temperature is nearly negligible, whereas observed strong magnetic field
+dependence correlates with the magnetic anisotropy of the sample. Finally, the
+role of the SAW pulses in both the ignition and formation of the deflagration
+front was also studied, and we show that the thermal diffusivity of Gd5Ge4 must
+be anisotropic, following \kappaa>\kappab>\kappac.",1109.1127v1
+2011-09-07,"Spin wave theory study of neutron intensity, magnetic field, and anisotropy of Type IIA FCC antiferromagnet","We study the spin dynamics in a 3D quantum antiferromagnet on a face-centered
+cubic (FCC) lattice. The effects of magnetic field, single-ion anisotropy, and
+biquadratic interactions are investigated using linear spin wave theory with
+spins in a canted basis about the Type IIA FCC antiferromagnetic ground state
+structure which is known to be stable. We calculate the expected finite
+frequency neutron scattering intensity and give qualitative criteria for
+typical FCC materials MnO and CoO. The magnetization reduction due to quantum
+zero point fluctuations is also analyzed.",1109.1350v3
+2011-09-07,A theoretical analysis of inertia-like switching in magnets: applications to a synthetic antiferromagnet,"The magnetization dynamics of a synthetic antiferromagnet subject to a short
+magnetic field pulse, has been studied by using a combination of
+first-principles and atomistic spin dynamics simulations. We observe switching
+phenomena on the time scale of tens of picoseconds, and inertia-like behavior
+in the magnetization dynamics. We explain the latter in terms of a dynamic
+redistribution of magnetic energy from the applied field pulse to other
+possible energy terms, such as the exchange interaction and the magnetic
+anisotropy, without invoking concepts such as inertia of an antiferromagnetic
+vector. We also demonstrate that such dynamics can also be observed in a
+ferromagnetic material where the incident field pulse pumps energy to the
+magnetic anisotropy.",1109.1414v1
+2011-09-09,Towards an experimental realization of affinely transformed linearized QED vacuum via inverse homogenization,"Within the framework of quantum electrodynamics (QED), vacuum is a nonlinear
+medium which can be linearized for a rapidly time-varying electromagnetic field
+with a small amplitude subjected to a magnetostatic field. The linearized QED
+vacuum is a uniaxial dielectric-magnetic medium for which the degree of
+anisotropy is exceedingly small. By implementing an affine transformation of
+the spatial coordinates, the degree of anisotropy may become sufficiently large
+as to be readily perceivable. The inverse Bruggeman formalism can be
+implemented to specify a homogenized composite material (HCM) which is
+electromagnetically equivalent to the affinely transformed QED vacuum. This HCM
+can arise from remarkably simple component materials; for example, two
+isotropic dielectric materials and two isotropic magnetic materials, randomly
+distributed as oriented spheroidal particles.",1109.2125v1
+2011-09-11,Quadrupole Approximation for Para-Positronium in Relativistic Schrödinger Theory,"The non-relativistic energy levels of para-positronium are calculated in the
+quadrupole approximation of the interaction potential. This approximation
+technique takes into account the anisotropy of the electrostatic
+electron-positron interaction in the lowest order. The states due to different
+values of the quantum number $(l_z)$ of angular momentum are found to be no
+longer degenerate as is the case in the conventional theory. The physical
+origin of this elimination of the conventional degeneracy may intuitively be
+attributed to the state-dependent inertial \emph{broadening} of the rotating
+charge clouds; the corresponding \emph{anisotropic} deformation (in the
+quadrupole approximation) lowers then the negative electrostatic interaction
+energy. The result of this influence of anisotropy is that the states with
+$l_z=0$ adopt smaller binding energy whereas the states with maximal value of
+$|l_z|$ (for fixed principal quantum number $n$) have the largest binding
+energy within the angular momentum multiplet $(-|l_{z,\mathrm{max}}| \le l_z
+\le |l_{z,\mathrm{max}}|)$. This yields a certain kind of electric
+fine-structure splitting with the splitted RST levels being placed in a
+relatively narrow band around the (highly degenerated) conventional levels.",1109.2331v1
+2011-09-12,Three-Dimensional Structure of Solar Wind Turbulence,"We present a measurement of the scale-dependent, three-dimensional structure
+of the magnetic field fluctuations in inertial range solar wind turbulence with
+respect to a local, physically motivated coordinate system. The Alfvenic
+fluctuations are three-dimensionally anisotropic, with the sense of this
+anisotropy varying from large to small scales. At the outer scale, the magnetic
+field correlations are longest in the local fluctuation direction, consistent
+with Alfven waves. At the proton gyroscale, they are longest along the local
+mean field direction and shortest in the direction perpendicular to the local
+mean field and the local field fluctuation. The compressive fluctuations are
+highly elongated along the local mean field direction, although axially
+symmetric perpendicular to it. Their large anisotropy may explain why they are
+not heavily damped in the solar wind.",1109.2558v2
+2011-09-13,Elastodynamics of radially inhomogeneous spherically anisotropic elastic materials in the Stroh formalism,"A method is presented for solving elastodynamic problems in radially
+inhomogeneous elastic materials with spherical anisotropy, i.e.\ materials such
+that $c_{ijkl}= c_{ijkl}(r)$ in a spherical coordinate system
+${r,\theta,\phi}$. The time harmonic displacement field $\mathbf{u}(r,\theta
+,\phi)$ is expanded in a separation of variables form with dependence on
+$\theta,\phi$ described by vector spherical harmonics with $r$-dependent
+amplitudes. It is proved that such separation of variables solution is
+generally possible only if the spherical anisotropy is restricted to transverse
+isotropy with the principal axis in the radial direction, in which case the
+amplitudes are determined by a first-order ordinary differential system.
+Restricted forms of the displacement field, such as $\mathbf{u}(r,\theta)$,
+admit this type of separation of variables solutions for certain lower material
+symmetries. These results extend the Stroh formalism of elastodynamics in
+rectangular and cylindrical systems to spherical coordinates.",1109.2865v1
+2011-09-19,On the stability in weak topology of the set of global solutions to the Navier-Stokes equations,"Let $X$ be a suitable function space and let $\cG \subset X$ be the set of
+divergence free vector fields generating a global, smooth solution to the
+incompressible, homogeneous three dimensional Navier-Stokes equations. We prove
+that a sequence of divergence free vector fields converging in the sense of
+distributions to an element of $\cG$ belongs to $\cG$ if $n$ is large enough,
+provided the convergence holds ""anisotropically"" in frequency space. Typically
+that excludes self-similar type convergence. Anisotropy appears as an important
+qualitative feature in the analysis of the Navier-Stokes equations; it is also
+shown that initial data which does not belong to $\cG$ (hence which produces a
+solution blowing up in finite time) cannot have a strong anisotropy in its
+frequency support.",1109.4043v2
+2011-09-21,Anisotropic critical magnetic fluctuations in the ferromagnetic superconductor UCoGe,"We report neutron scattering measurements of critical magnetic excitations in
+the weakly ferromagnetic superconductor UCoGe. The strong non-Landau damping of
+the excitations we observe, although unusual has been found in another related
+ferromagnet, UGe2 at zero pressure. However, we also find there is a
+significant anisotropy of the magnetic correlation length in UCoGe that
+contrasts with an almost isotropic length for UGe2. The values of the magnetic
+correlation length and damping are found to be compatible with
+superconductivity on small Fermi surface pockets. The anisotropy may be
+important to explain why UCoGe is a superconductor at zero pressure while UGe2
+is not.",1109.4541v1
+2011-09-22,Ground-state phases of ultracold bosons with Rashba-Dresselhaus spin-orbit coupling,"We study ultracold bosons in three dimensions with an anisotropic
+Rashba-Dresselhaus spin-orbit coupling. We first carry out the exact summation
+of ladder diagrams for the two-boson t-matrix at zero energy. Then, with the
+t-matrix as the effective interaction, we find the ground-state phase diagrams
+of bosons in mean field as a function of the spin-orbit coupling, the
+anisotropy, and the scattering lengths between particles in the same and in
+different pseudospin states. The resulting phase diagrams have much richer
+structures than those obtained using mean-field couplings, exhibiting three
+different phases: a plane-wave condensate, a striped condensate, and an
+unstable phase. The differences between the present approach using the t-matrix
+compared to using mean-field couplings is significant for large scattering
+lengths, large spin-orbit-coupling strength, or small anisotropy.",1109.4954v2
+2011-09-27,Counting hot/cold spots in quark-gluon plasma,"We study how local fluctuations in the initial states of relativistic
+heavy-ion collisions manifest themselves in the correlations between different
+orders of harmonic moments of the density profiles, particularly those
+involving only odd harmonics which purely arise from initial state
+fluctuations. We find the strengths of those correlations are sensitive to the
+number of hot and cold spots in the initial states. Hydrodynamic evolution of
+the fireball translates initial state geometric anisotropies as well as their
+correlations into final state momentum anisotropies and correlations. We
+conclude that the measurement of the correlations between different harmonic
+moments of final state azimuthal distribution can be employed to quantify the
+inhomogeneity of the initial density profiles such as the population of hot and
+cold spots that are produced in high energy nuclear collisions.",1109.5961v3
+2011-09-28,Anisotropic vortex lattice structures in the FeSe superconductor,"In the recent work by Song et al. [Science 332, 1410 (2011)], the scanning
+tunneling spectroscopy experiment in the stoichiometric FeSe reveals evidence
+for nodal superconductivity and strong anisotropy. The nodal structure can be
+explained with the extended s-wave pairing structure with the mixture of the
+$s_{x^2+y^2}$ and $s_{x^2y^2}$ pairing symmetries. We calculate the anisotropic
+vortex structure by using the self-consistent Bogoliubov-de Gennes mean-field
+theory. In considering the absence of magnetic ordering in the FeSe at the
+ambient pressure, orbital ordering is introduced, which breaks the $C_4$
+lattice symmetry down to $C_2$, to explain the anisotropy in the vortex
+tunneling spectra.",1109.6116v3
+2011-09-30,Entanglement Perturbation Theory for Antiferromagnetic Heisenberg Spin Chains,"A recently developed numerical method, entanglement perturbation theory
+(EPT), is used to study the antiferromagnetic Heisenberg spin chains with
+z-axis anisotropy $\lambda$ and magnetic field B. To demonstrate the accuracy,
+we first apply EPT to the isotropic spin-1/2 antiferromagnetic Heisenberg
+model, and find that EPT successfully reproduces the exact Bethe Ansatz results
+for the ground state energy, the local magnetization, and the spin correlation
+functions (Bethe ansatz result is available for the first 7 lattice
+separations). In particular, EPT confirms for the first time the asymptotic
+behavior of the spin correlation functions predicted by the conformal field
+theory, which realizes only for lattice separations larger than 1000. Next,
+turning on the z-axis anisotropy and the magnetic field, the 2-spin and 4-spin
+correlation functions are calculated, and the results are compared with those
+obtained by Bosonization and density matrix renormalization group methods.
+Finally, for the spin-1 antiferromagnetic Heisenberg model, the ground state
+phase diagram in $\lambda$ space is determined with help of the Roomany-Wyld RG
+finite-size-scaling. The results are in good agreement with those obtained by
+the level-spectroscopy method.",1109.6758v1
+2011-09-30,Transport in Anisotropic Superfluids: A Holographic Description,"We study transport phenomena in p-wave superfluids in the context of
+gauge/gravity duality. Due to the spacetime anisotropy of this system, the
+tensorial structure of the transport coefficients is non-trivial in contrast to
+the isotropic case. In particular, there is an additional shear mode which
+leads to a non-universal value of the shear viscosity even in an Einstein
+gravity setup. In this paper, we present a complete study of the helicity two
+and helicity one fluctuation modes. In addition to the non-universal shear
+viscosity, we also investigate the thermoelectric effect, i.e. the mixing of
+electric and heat current. Moreover, we also find an additional effect due to
+the anisotropy, the so-called flexoelectric effect.",1110.0007v2
+2011-10-04,Weak lensing of CMB by cosmic (super-)strings,"We study the effect of weak lensing by cosmic (super-)strings on the
+anisotropies of cosmic microwave background (CMB). In developing a method to
+calculate the lensing convergence field due to strings, and thereby temperature
+and polarization angular power spectra of CMB, we clarify how the nature of
+strings, characterized by the intercommuting probability, can influence these
+CMB anisotropies. Assuming that the power spectrum is dominated by
+Poisson-distributed string segments, we find that the convergence spectrum
+peaks at low multipoles and is mostly contributed from strings located at
+relatively low redshifts. As the intercommuting probability decreases, the
+spectra of the convergence and hence the lensed temperature and polarizations
+are gained because the number density of string segments becomes larger. An
+observationally important feature of the string-induced CMB polarizations is
+that the string-lensed spectra decay more slowly on small scales compared with
+primordial scalar perturbations from standard inflation.",1110.0556v3
+2011-10-04,Low-temperature thermodynamics of the classical frustrated ferromagnetic chain in magnetic field,"Low-temperature magnetization curves of the classical frustrated
+ferromagnetic chain in the external magnetic field near the transition point
+between the ferromagnetic and the helical phases is studied. It is shown that
+the calculation of the partition function in the scaling limit reduces to the
+solution of the Schr\""{o}dinger equation of the special form for the quantum
+particle. It is proposed that the magnetization of the classical model in the
+ferromagnetic part of the phase diagram including the transition point defines
+the universal scaling function which is valid for quantum model as well.
+Explicit analytical formulae for the magnetization are given in the limiting
+cases of low and high magnetic fields. The influence of the easy-axis
+anisotropy on the magnetic properties of the model is studied. It is shown that
+even small anisotropy essentially changes the behavior of the susceptibility in
+the vicinity of the transition point.",1110.0771v2
+2011-10-11,Deposition of general ellipsoidal particles,"We present a systematic overview of granular deposits composed of ellipsoidal
+particles with different particle shapes and size polydispersities. We study
+the density and anisotropy of such deposits as functions of size polydispersity
+and two shape parameters that fully describe the shape of a general ellipsoid.
+Our results show that, while shape influences significantly the macroscopic
+properties of the deposits, polydispersity plays apparently a secondary role.
+The density attains a maximum for a particular family of non-symmetrical
+ellipsoids, larger than the density observed for prolate or oblate ellipsoids.
+As for anisotropy measures, the contact forces show are increasingly preferred
+along the vertical direction as the shape of the particles deviates for a
+sphere. The deposits are constructed by means of an efficient molecular
+dynamics method, where the contact forces are efficiently and accurately
+computed. The main results are discussed in the light of applications for
+porous media models and sedimentation processes.",1110.2792v1
+2011-10-15,A Field-directional Specific Heat Study on the Gap Structure of Overdoped Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$,"Low-temperature specific heat is measured on the overdoped
+Ba(Fe_{1-x}Co_x)_2As_2 (x = 0.13) single crystal under magnetic fields along
+three different directions. A clear anisotropy is observed on the field
+dependent electronic specific heat coefficient {\gamma}(H). The value of
+{\gamma}(H) is obviously larger with magnetic field along [001] (c-axis) than
+that within the ab-plane of the crystal lattice, which cannot be attributed to
+the effect by anisotropy of the upper critical field. Meanwhile, the data show
+a rather small difference when the direction of the field is rotated from [100]
+to [110] direction within the ab-plane. Our results suggest that a considerable
+part of the line nodes is not excited to contribute to the quasiparticle
+density of states by the field when the field is within the ab-plane. The
+constraints on the topology of the gap nodes are discussed based on our
+observations.",1110.3403v2
+2011-10-17,Quadrupole oscillation in a dipolar Fermi gas: hydrodynamic vs collisionless regime,"The surface quadrupole mode of an harmonically trapped dipolar Fermi gas is
+studied in both the hydrodynamic and collisionless regimes. The anisotropy and
+long range effects of the dipolar force as well as the role of the trapping
+geometry are explicitly investigated. In the hydrodynamic regime the frequency
+is always slightly smaller than the $\sqrt{2}\omega_\perp$ value holding for
+gases interacting with contact interactions. In the collisionless regime the
+frequency can be either pretty smaller or larger than the non-interacting value
+$2\omega_\perp$, depending on the cloud aspect ratio. Our results suggest that
+the frequency of the surface quadrupole oscillation can provide a useful test
+for studying, at very low temperatures, the transition between the normal and
+the superfluid phase and, in the normal phase at higher temperatures, the
+crossover between the collisional and collisionless regimes. The consequences
+of the anisotropy of the dipolar force on the virial theorem are also
+discussed.",1110.3670v1
+2011-10-21,Schwarzschild models of the Sculptor dSph galaxy,"We have developed a spherically symmetric dynamical model of a dwarf
+spheroidal galaxy using the Schwarzschild method. This type of modelling yields
+constraints both on the total mass distribution (e.g. enclosed mass and scale
+radius) as well as on the orbital structure of the system modelled (e.g.
+velocity anisotropy). Therefore not only can we derive the dark matter content
+of these systems, but also explore possible formation scenarios. Here we
+present preliminary results for the Sculptor dSph. We find that the mass of
+Sculptor within 1kpc is 8.5\times10^(7\pm0.05) M\odot, its anisotropy profile
+is tangentially biased and slightly more isotropic near the center. For an NFW
+profile, the preferred concentration (~15) is compatible with cosmological
+models. Very cuspy density profiles (steeper than NFW) are strongly disfavoured
+for Sculptor.",1110.4808v1
+2011-11-01,Theory of quasiparticle vortex bound states in Fe-based superconductors: application to LiFeAs,"Spectroscopy of vortex bound states can provide valuable information on the
+structure of the superconducting order parameter. Quasiparticle wavefunctions
+are expected to leak out in the directions of gap minima or nodes, if they
+exist, and scanning tunneling spectroscopy (STS) on these low-energy states
+should probe the momentum dependence of the gap. Anisotropy can also arise from
+band structure effects, however. We perform a quasiclassical calculation of the
+density of states of a single vortex in an anisotropic superconductor, and show
+that if the gap itself is not highly anisotropic, the Fermi surface anisotropy
+dominates, preventing direct observation of superconducting gap features. This
+serves as a cautionary message for the analysis of STS data on the vortex state
+on Fe-based superconductors, in particular LiFeAs, which we treat explicitly.",1111.0126v1
+2011-11-06,Continuous Time Monte Carlo for Lattice QCD in the Strong Coupling Limit,"We present results for lattice QCD with staggered fermions in the limit of
+infinite gauge coupling, obtained from a worm-type Monte Carlo algorithm on a
+discrete spatial lattice but with continuous Euclidean time. This is achieved
+by sending both the anisotropy parameter $\gamma^2\simeq a/\at$ and the number
+of time-slices $N_\tau$ to infinity, keeping the ratio $\gamma^2/N_\tau \simeq
+aT$ fixed. In this limit, ambiguities arising from the anisotropy parameter
+$\gamma$ are eliminated and discretization errors usually introduced by a
+finite temporal lattice extent $\Nt$ are absent. The obvious gain is that no
+continuum extrapolation $N_\tau \rightarrow \infty$ has to be carried out.
+Moreover, the algorithm is faster and the sign problem disappears completely.
+  As a first application, we determine the phase diagram as a function of
+temperature and real and imaginary baryon chemical potential. We compare our
+computations with those on lattices with discrete Euclidean time.
+Discretization errors due to finite $\Nt$ in previous studies turn out to be
+large at low temperatures.",1111.1434v1
+2011-11-10,Highlights from Telescope Array,"The results from the first three years observation in Telescope Array are
+reviewed. The energy spectrum, mass composition, and anisotropy in arrival
+directions of ultra-high energy cosmic rays are discussed. The energy spectrum
+of cosmic rays with energies above $10^{18}$ eV is determined using the data of
+the fluorescence detectors, surface detectors, and with a hybrid shower
+reconstruction technique using the both data. The ankle structure is clearly
+found at $10^{18.7}$ eV. The second bending point is also identified, at which
+the flux of cosmic rays begins to decrease and the spectral index changes from
+$E^{-2.68}$ to $E^{-4.2}$. The study of shower development using the
+fluorescence detector data shows that proton is dominant in cosmic rays above
+$10^{18.2}$ eV. No apparent anisotropies in the arrival direction of cosmic
+rays are found. I also present further experimental extensions which are being
+developed at the Telescope Array site.",1111.2507v1
+2011-11-15,Unconventional Anisotropic s-Wave Superconducting Gaps of LiFeAs Iron-Pnictide Superconductor,"We have performed high-resolution angle-resolved photoemission spectroscopy
+on Fe-based superconductor LiFeAs (Tc = 18 K). We reveal multiple nodeless
+superconducting (SC) gaps with 2D/kBTc ratios varying from 2.8 to 6.4,
+depending on the Fermi surface (FS). We also succeeded in directly observing a
+gap anisotropy along the FS with magnitude up to ~30 %. The anisotropy is
+four-fold symmetric with an antiphase between the hole and electron FSs,
+suggesting complex anisotropic interactions for the SC pairing. The observed
+momentum dependence of the SC gap offers an excellent opportunity to
+investigate the underlying pairing mechanism.",1111.3496v2
+2011-11-16,On Wormhole Throats in $f(R)$ Gravity Theory,"We study the existence and properties of wormhole throats in modified $f(R)$
+gravity theory. Specifically, we concentrate on the cases where the lapse is
+not necessarily constant, and hence are not limited to the zero tidal force
+scenarios. In the class of theories whose actions are generated by Lagrangians
+of the form $f(R)=\sum \alpha_{n}\,R^{n}$ we find parameters which allow for
+the existence of energy condition respecting throats, which do not exist in
+Einstein gravity. We also consider the effect of the modified action on the
+anisotropy of the models, and find that modified gravity can minimize the
+amount of anisotropy required to support the existence of a throat. In both
+these respects, the sector containing theories with positive $n$ is more
+promising than the negative $n$ sector in comparison to Einstein gravity alone,
+with large $n$ being most favorable",1111.3704v2
+2011-11-26,Electronic reconstruction through the structural and magnetic transitions in detwinned NaFeAs,"We use angle-resolved photoemission spectroscopy to study twinned and
+detwinned iron pnictide compound NaFeAs. Distinct signatures of electronic
+reconstruction are observed to occur at the structural (TS) and magnetic (TSDW)
+transitions. At TS, C4 rotational symmetry is broken in the form of an
+anisotropic shift of the orthogonal dxz and dyz bands. The magnitude of this
+orbital anisotropy rapidly develops to near completion upon approaching TSDW,
+at which temperature band folding occurs via the antiferromagnetic ordering
+wave vector. Interestingly, the anisotropic band shift onsetting at TS develops
+in such a way to enhance the nesting conditions in the C2 symmetric state,
+hence is intimately correlated with the long range collinear AFM order.
+Furthermore, the similar behaviors of the electronic reconstruction in NaFeAs
+and Ba(Fe1-xCox)2As2 suggests that this rapid development of large orbital
+anisotropy between TS and TSDW is likely a general feature of the electronic
+nematic phase in the iron pnictides, and the associated orbital fluctuations
+may play an important role in determining the ground state properties.",1111.6134v1
+2011-11-29,Theory of Spin Relaxation in Two-Electron Lateral Coupled Quantum Dots,"A global quantitative picture of the phonon-induced two-electron spin
+relaxation in GaAs double quantum dots is presented using highly accurate
+numerical calculations. Wide regimes of interdot coupling, magnetic field
+magnitude and orientation, and detuning are explored in the presence of a
+nuclear bath. Most important, the unusually strong magnetic anisotropy of the
+singlet-triplet relaxation can be controlled by detuning switching the
+principal anisotropy axes: a protected state becomes unprotected upon detuning,
+and vice versa. It is also established that nuclear spins can dominate spin
+relaxation for unpolarized triplets even at high magnetic fields, contrary to
+common belief. These findings are central to designing quantum dots geometries
+for spin-based quantum information processing with minimal environmental
+impact.",1111.6724v3
+2011-11-29,Anisotropy of Electrical Transport in Pnictide Superconductors Studied Using Monte Carlo Simulations of the Spin-Fermion Model,"The undoped three-orbital spin fermion model for the Fe-based superconductors
+is studied via Monte Carlo techniques in two-dimensional clusters. At low
+temperatures, the magnetic and one-particle spectral properties are in good
+agreement with neutron and photoemission experiments. Our most important
+results are the resistance vs. temperature curves that display all the features
+experimentally observed in BaFe$_2$As$_2$ detwinned single crystals (under
+uniaxial stress), including a low-temperature anisotropy between the two
+directions followed by a peak at the magnetic ordering temperature, here
+induced by short-range spin order and concomitant Fermi Surface orbital order.",1111.6994v4
+2011-12-02,Two-dimensional arrays of superconducting strips as dc magnetic metamaterials,"We theoretically investigate the magnetic response of two-dimensional arrays
+of superconducting strips, which are regarded as essential structures of dc
+magnetic metamaterials. We analytically obtain local distributions of the
+magnetic field for the ideal complete shielding state (i.e., $\Lambda/w\to 0$,
+where $2w$ is the strip width, $\Lambda=\lambda^2/d$ is the Pearl length,
+$\lambda$ is the London penetration depth, and $d$ is the strip thickness), and
+derive effective permeability by averaging the local field distributions. We
+also perform numerical calculations for a realistic case, taking finite
+$\Lambda/w>0$ into account. We investigate two types of strip arrays: a
+rectangular array and a hexagonal array. The resulting effective permeability
+has large anisotropy that depends on the dimensions and arrangement of the
+superconducting strips, and the hexagonal array is found to be more
+advantageous for obtaining large anisotropy than the rectangular array.",1112.0372v1
+2011-12-05,Quantum magnets with large single-ion easy-plane anisotropy in transverse magnetic field,"We discuss low-temperature properties of magnets with integer spin and large
+single-ion easy-plane anisotropy $D$ in transverse magnetic field $h$.
+Considering the exchange interaction between spins as a perturbation and using
+the diagram technique we derive at $h\sim D$ in the first nonvanishing orders
+of the perturbation theory thermal corrections to the elementary excitation
+spectrum, magnetization and specific heat. An expression for the boundary
+$h_{c1}(T)$ is found in the $h$-$T$ plane between the paramagnetic phase and
+that with the long range magnetic order. The effective interaction is derived
+between bosons near the quantum critical point $h_{c1}(0)$. The proposed theory
+describes well experimental data obtained in $\rm NiCl_2$-$\rm 4SC(NH_2)_2$
+(DTN).",1112.0833v1
+2011-12-05,Magnetic anisotropy of elongated thin ferromagnetic nano-islands for artifical spin ice arrays,"The energetics of thin elongated ferromagnetic nano-islands is considered for
+some different shapes, aspect ratios, and applied magnetic field directions.
+These nano-island particles are important for artificial spin-ice materials.
+For low temperature, the magnetic internal energy of an individual particle is
+evaluated numerically as a function of the direction of a particle's net
+magnetization. This leads to estimations of effective anisotropy constants for
+(1) the easy axis along the particle's long direction, and (2) the hard axis
+along the particle's thin direction. A spin relaxation algorithm together with
+fast Fourier transform for the demagnetization field is used to solve the
+micromagnetics problem for a thin system. The magnetic hysteresis is also
+found. The results indicate some possibilities for controlling the equilibrium
+and dynamics in spin-ice materials by using different island geometries.",1112.0913v2
+2011-12-07,Exciton coherence lifetimes from electronic structure,"We model the coherent energy transfer of an electronic excitation within
+covalently linked aromatic homodimers from first-principles, to answer whether
+the usual models of the bath calculated via detailed electronic structure
+calculations can reproduce the key dynamics. For these systems the timescales
+of coherent transport are experimentally known from time-dependent polarization
+anisotropy measurements, and so we can directly assess the whether current
+techniques might be predictive for this phenomenon. Two choices of electronic
+basis states are investigated, and their relative merits discussed regarding
+the predictions of the perturbative model. The coupling of the electronic
+degrees of freedom to the nuclear degrees of freedom is calculated rather than
+assumed, and the fluorescence anisotropy decay is directly reproduced.
+Surprisingly we find that although TDDFT absolute energies are routinely in
+error by orders of magnitude more than the coupling energy, the coherent
+transport properties of these dimers can be semi-quantitatively reproduced from
+first-principles. The directions which must be pursued to yield predictive and
+reliable prediction of coherent transport are suggested.",1112.1665v2
+2011-12-09,Helium-4 Synthesis in an Anisotropic Universe,"We calculate the 4He abundance in a universe of Bianchi type I whose cosmic
+anisotropy is dynamically generated by a fluid with anisotropic equation of
+state. Requiring that the relative variation of mass fraction of 4He is less
+than 4% with respect to the standard isotropic case to be consistent with
+astrophysical data, we constrain the parameter of cosmic anisotropy, the shear
+\Sigma, as |\Sigma(T_f)| < 0.4, where T_f is the freeze-out temperature of the
+weak interactions that interconvert neutrons and protons. Anisotropic fluids,
+whose energy density is subdominant with respect to the energy content of the
+Universe during inflation and radiation era, generate much smaller shears at
+the time of freeze-out and then do not appreciably affect the standard 4He
+production. This is the case of anisotropic dark energy, and of a uniform
+magnetic field with energy density much smaller than about 1.25 times the
+energy density of neutrinos.",1112.2076v2
+2011-12-17,Effect of temperature-dependent eta/s on flow anisotropies,"We investigate the effects of a temperature-dependent shear viscosity over
+entropy density ratio eta/s on the flow anisotropy coefficients v_2 and v_4 in
+ultrarelativistic heavy-ion collisions at RHIC and LHC. We find that v_4 is
+more sensitive to the viscosity at low temperatures than v_2. At RHIC v_2 is
+mostly affected by the viscosity around the phase transition, but the larger
+the collision energy, the more the quark-gluon plasma viscosity affects v_2.",1112.4081v1
+2011-12-21,Role of Interstitial Pinning in the Dynamical Phases of Vortices in Superconducting Films,"We analyze the vortex dynamics in superconducting thin films with a periodic
+array of pinning centers. In particular, we study the effect of anisotropy for
+a Kagom\'e pinning network when longitudinal and transverse transport currents
+are applied. By solving the equations of motion for the vortex array
+numerically at zero temperature we find different phases for the vortex
+dynamics depending on the pinning and driving force. An unusual sequence of
+peaks along and perpendicular to the main hexagonal lattice axes is observed
+for the differential resistance reflecting the anisotropy of the transport
+properties and the complex behavior of the vortex system. This behavior may be
+understood in terms of interstitial pinning vacancies, which create channels of
+vortices with different pinning strength.",1112.5001v1
+2011-12-22,Magnetic structure of noncentrosymmetric perovskites PbVO3 and BiCoO3,"It is well known that if a crystal structure has no inversion symmetry, it
+may allow for Dzyaloshinskii-Moriya magnetic interactions, operating between
+different crystallographic unit cells, which in turn should lead to the
+formation of long-periodic spin-spiral structures. Such a behavior is
+anticipated for two simple perovskites PbVO3 and BiCoO3, crystallizing in the
+noncentrosymmetric tetragonal P4mm structure. Nevertheless, we argue that in
+reality PbVO3 and BiCoO3 should behave very differently. Due to the fundamental
+Kramers degeneracy for the odd-electron systems, PbVO3 has no single-ion
+anisotropy. Therefore, the ground state of PbVO3 will be indeed the spin spiral
+with the period of about one hundred unit cells. However, the even-electron
+BiCoO3 has a large single-ion anisotropy, which locks this system in the
+collinear easy-axis C-type antiferromagnetic ground state. Our theoretical
+analysis is based on the low-energy model, derived from the first-principles
+electronic structure calculations.",1112.5219v1
+2011-12-30,First-Order Reorientation of the Flux-Line Lattice in CaAlSi,"The flux line lattice in CaAlSi has been studied by small angle neutron
+scattering. A well defined hexagonal flux line lattice is seen just above Hc1
+in an applied field of only 54 Oe. A 30 degree reorientation of this vortex
+lattice has been observed in a very low field of 200 Oe. This reorientation
+transition appears to be of first-order and could be explained by non-local
+effects. The magnetic field dependence of the form factor is well described by
+a single penetration depth of 1496(1) angstroms and a single coherence length
+of 307(1) angstroms at 2 K. At 1.5 K the penetration depth anisotropy is 2.7(1)
+with the field applied perpendicular to the c axis and agrees with the
+coherence length anisotropy determined from critical field measurements.",1201.0174v1
+2012-01-12,The Oddly Quiet Universe: How the CMB challenges cosmology's standard model,"We discuss selected large-scale anomalies in the maps of temperature
+anisotropies in the cosmic microwave background. Specfically, these include
+alignments of the largest modes of CMB anisotropy with one another and with the
+geometry and direction of motion of the Solar System, and the unexpected
+absence of two-point angular corellations especially outside the region of the
+sky most contaminated by the Galaxy. We discuss these findings in relation to
+expectations from standard inflationary cosmology. This paper is adapted from a
+talk given by one of us (GDS) at the SEENET-2011 meeting in August 2011 on the
+Serbian bank of the Danube River.",1201.2459v1
+2012-01-12,Universal behavior of the upper critical field in iron based superconductors,"The newly discovered iron-based high temperature superconductors have
+demonstrated rich physical properties. Here we give a brief review on the
+recent studies of the upper critical field and its anisotropy in a few typical
+series of the iron-based superconductors (FeSCs). In spite of their characters
+of a layered crystal structure, all the FeSCs possess an extremely large upper
+critical field and a weak anisotropy of superconductivity, being unique among
+the layered superconductors. These particular properties indicate potential
+applications of the FeSCs in the future. Based on the experimental facts of the
+FeSCs, we will discuss the possible mechanisms of pair breaking in high
+magnetic fields and its restrictions on the theoretical analysis of the
+superconducting pairing mechanisms.",1201.2548v1
+2012-01-13,Cylindrically Symmetric Relativistic Fluids: A Study Based on Structure Scalars,"The full set of equations governing the structure and the evolution of
+self--gravitating cylindrically symmetric dissipative fluids with anisotropic
+stresses, is written down in terms of scalar quantities obtained from the
+orthogonal splitting of the Riemann tensor (structure scalars), in the context
+of general relativity. These scalars which have been shown previously (in the
+spherically symmetric case) to be related to fundamental properties of the
+fluid distribution, such as: energy density, energy density inhomogeneity,
+local anisotropy of pressure, dissipative flux, active gravitational mass etc,
+are shown here to play also a very important role in the dynamics of
+cylindrically symmetric fluids. It is also shown that in the static case, all
+possible solutions to Einstein equations may be expressed explicitly through
+three of these scalars.",1201.2862v3
+2012-01-18,Spectroscopy of spin-orbit quantum bits in indium antimonide nanowires,"Double quantum dot in the few-electron regime is achieved using local gating
+in an InSb nanowire. The spectrum of two-electron eigenstates is investigated
+using electric dipole spin resonance. Singlet-triplet level repulsion caused by
+spin-orbit interaction is observed. The size and the anisotropy of
+singlet-triplet repulsion are used to determine the magnitude and the
+orientation of the spin-orbit effective field in an InSb nanowire double dot.
+The obtained results are confirmed using spin blockade leakage current
+anisotropy and transport spectroscopy of individual quantum dots.",1201.3707v2
+2012-01-25,Inflation with Multi-Vector-Hair: The Fate of Anisotropy,"We study inflation with multiple vector fields. In the presence of
+non-trivial couplings between the inflaton and the vector fields, it turns out
+that no-hair conjecture does not hold and vector-hair appears. In the case of
+uniform couplings, nevertheless, we find that the universe approaches an
+isotropic final state after transient anisotropic inflationary phases. For
+general couplings, we numerically show attractors are anisotropic inflation.
+Even in these cases, it turns out that the inflation always tends to minimize
+the anisotropy in the expansion of the universe.",1201.5309v2
+2012-01-28,A cosmological concordance model with dynamical vacuum term,"We demonstrate that creation of dark-matter particles at a constant rate
+implies the existence of a cosmological term that decays linearly with the
+Hubble rate. We discuss the cosmological model that arises in this context and
+test it against observations of the first acoustic peak in the cosmic microwave
+background (CMB) anisotropy spectrum, the Hubble diagram for supernovas of type
+Ia (SNIa), the distance scale of baryonic acoustic oscillations (BAO) and the
+distribution of large scale structures (LSS). We show that a good concordance
+is obtained, albeit with a higher value of the present matter abundance than in
+the \Lambda CDM model. We also comment on general features of the CMB
+anisotropy spectrum and on the cosmic coincidence problem.",1201.5919v2
+2012-01-30,"Exchange constants and spin waves of the orbital ordered, non-collinear spinel MnV$_2$O$_4$","We study the exchange constants of MnV$_2$O$_4$ using magnetic force theorem
+and local spin density approximation of density functional theory supplemented
+with a correction due to on-site Hubbard interaction U. We obtain the exchanges
+for three different orbital orderings of the Vanadium atoms of the spinel. We
+then map the exchange constants to a Heisenberg model with single-ion
+anisotropy and solve for the spin-wave excitations in the non-collinear, low
+temperature phase of the spinel. The single-ion anisotropy parameters are
+obtained from an atomic multiplet exact-diagonalization program, taking into
+effect the crystal-field splitting and the spin-orbit coupling. We find good
+agreement between the spin waves of one of our orbital ordered setups with
+previously reported experimental spin waves as determined by neutron
+scattering. We can therefore determine the correct orbital order from various
+proposals that exist in the literature.",1201.6375v2
+2012-01-31,How well-proportioned are lens and prism spaces?,"The CMB anisotropies in spherical 3-spaces with a non-trivial topology are
+analysed with a focus on lens and prism shaped fundamental cells. The
+conjecture is tested that well proportioned spaces lead to a suppression of
+large-scale anisotropies according to the observed cosmic microwave background
+(CMB). The focus is put on lens spaces L(p,q) which are supposed to be oddly
+proportioned. However, there are inhomogeneous lens spaces whose shape of the
+Voronoi domain depends on the position of the observer within the manifold.
+Such manifolds possess no fixed measure of well-proportioned and allow a
+predestined test of the well-proportioned conjecture. Topologies having the
+same Voronoi domain are shown to possess distinct CMB statistics which thus
+provide a counter-example to the well-proportioned conjecture. The CMB
+properties are analysed in terms of cyclic subgroups Z_p, and new point of view
+for the superior behaviour of the Poincar\'e dodecahedron is found.",1201.6490v1
+2012-02-06,Quantum phase transitions of 2-d dimerized spin-1/2 Heisenberg models with spatial anisotropy,"Motivated by the unexpected Monte Carlo results as well as the theoretical
+proposal of a large correction to scaling for the critical theory of the 2-d
+staggered-dimer spin-1/2 Heisenberg model on the square lattice, we study the
+phase transitions induced by dimerization of several dimerized quantum
+Heisenberg models with spatial anisotropy using first principles Monte Carlo
+method. Remarkably, while our Monte Carlo data for all the models considered
+here, including the herringbone- and ladder-dimer models on the square lattice,
+are compatible with the recently proposed scenario of an enhanced correction to
+scaling, we find it is likely that the enhanced correction to scaling manifests
+itself as amplification of the nonuniversal prefactors appeared in the scaling
+forms. In other words, our data are in consistence with the established
+numerical values for the critical exponents, including the confluent exponent,
+in the O(3) universality class. Convincing numerical evidence is provided to
+support this proposed scenario.",1202.1057v2
+2012-02-13,Cosmological parameters constraints from galaxy cluster mass function measurements in combination with other cosmological data,"We present the cosmological parameters constraints obtained from the
+combination of galaxy cluster mass function measurements (Vikhlinin et al.,
+2009a,b) with new cosmological data obtained during last three years: updated
+measurements of cosmic microwave background anisotropy with Wilkinson Microwave
+Anisotropy Probe (WMAP) observatory, and at smaller angular scales with South
+Pole Telescope (SPT), new Hubble constant measurements, baryon acoustic
+oscillations and supernovae Type Ia observations.
+  New constraints on total neutrino mass and effective number of neutrino
+species are obtained. In models with free number of massive neutrinos the
+constraints on these parameters are notably less strong, and all considered
+cosmological data are consistent with non-zero total neutrino mass \Sigma m_\nu
+\approx 0.4 eV and larger than standard effective number of neutrino species,
+N_eff \approx 4. These constraints are compared to the results of neutrino
+oscillations searches at short baselines.
+  The updated dark energy equation of state parameters constraints are
+presented. We show that taking in account systematic uncertainties, current
+cluster mass function data provide similarly powerful constraints on dark
+energy equation of state, as compared to the constraints from supernovae Type
+Ia observations.",1202.2889v1
+2012-02-16,Transport and magnetic properties of La-doped CaFe$_2$As$_2$,"We measured the transport properties and susceptibility of single crystals
+Ca$_{1-x}$La$_x$Fe$_2$As$_2$(x=0, 0.05, 0.1, 0.15, 0.19 and 0.25). Large
+in-plane resistivity anisotropy similar to that in Co-doped 122 iron-pnictides
+is observed although no transition metals were introduced in the FeAs-plane.
+The in-plane resistivity anisotropy gradually increases with La doping below
+T$_{SDW}$, being different from the hole-doped 122 superconductors. The
+susceptibilities of the samples show that La doping leads to suppression of SDW
+and induces a Curie-Weiss-like behavior at low temperature, which is much
+stronger than the other 122 iron-based superconductors.",1202.3589v1
+2012-02-21,Theoretical studies of 63Cu Knight shifts of the normal state of YBa2Cu3O7,"The 63Cu Knight shifts and g factors for the normal state of YBa2Cu3O7 in
+tetragonal phase are theoretically studied in a uniform way from the high
+(fourth-) order perturbation formulas of these parameters for a 3d9 ion under
+tetragonally elongated octahedra. The calculations are quantitatively
+correlated with the local structure of the Cu2+(2) site in YBa2Cu3O7. The
+theoretical results show good agreement with the observed values, and the
+improvements are achieved by adopting fewer adjustable parameters as compared
+to the previous works. It is found that the significant anisotropy of the
+Knight shifts is mainly attributed to the anisotropy of the g factors due to
+the orbital interactions.",1202.4598v1
+2012-02-23,Cross-correlation of WISE Galaxies with the Cosmic Microwave Background,"We estimated the cross-power spectra of a galaxy sample from the Wide-field
+Infrared Survey Explorer (WISE) survey with the 7-year Wilkinson Microwave
+Anisotropy Probe (WMAP) temperature anisotropy maps. A conservatively-selected
+galaxy sample covers ~13000sq.deg, with a median redshift of z=0.15.
+Cross-power spectra show correlations between the two data sets with no
+discernible dependence on the WMAP Q, V and W frequency bands. We interpret
+these results in terms of the the Integrated Sachs-Wolfe (ISW) effect: for the
+|b|>20 deg sample at l=6-87, we measure the amplitude (normalized to be 1 for
+vanilla LambdaCDM expectation) of the signal to be 3.4+-1.1, i.e., 3.1 sigma
+detection. We discuss other possibilities, but at face value, the detection of
+the linear ISW effect in a flat universe is caused by large scale decaying
+potentials, a sign of accelerated expansion driven by Dark Energy.",1202.5306v1
+2012-02-27,"Crystalline anisotropic magnetoresistance with two-fold and eight-fold symmetry in (In,Fe)As ferromagnetic semiconductor","We have investigated the anisotropic magnetoresistance (AMR) of (In,Fe)As
+ferromagnetic semiconductor (FMS) layers grown on semi-insulating GaAs
+substrates. In a 10 nm-thick (In,Fe)As layer which is insulating at low
+temperature, we observed crystalline AMR with two-fold and eight-fold
+symmetries. In a metallic 100 nm-thick (In,Fe)As layer with higher electron
+concentration, only two-fold symmetric crystalline AMR was observed. Our
+results demonstrate the macroscopic ferromagnetism in (In,Fe)As with magnetic
+anisotropy that depends on the electron concentration. Non-crystalline AMR is
+also observed in the 100 nm-thick layer, but its magnitude is as small as
+10^-5, suggesting that there is no s-d scattering near the Fermi level of
+(In,Fe)As. We propose the origin of the eight-fold symmetric crystalline
+anisotropy in (In,Fe)As.",1202.5874v1
+2012-03-01,Step bunching process induced by the flow of steps at the sublimated crystal surface,"Stepped GaN(0001) surface is studied by the kinetic Monte Carlo method and
+compared with the model based on Burton-Carbera-Frank equations. Successive
+stages of surface pattern evolution during high temperature sublimation process
+are discussed. At low sublimation rates clear, well defined step bunches form.
+The process happens in the absence or for very low Schwoebel barriers at the
+ideal surface. Bunches of several steps are well separated, move slowly and are
+rather stiff. Character of the process changes for more rapid sublimation
+process where double step formations become dominant and together with meanders
+and local bunches assemble into the less ordered surface pattern. Solution of
+the analytic equations written for one dimensional system confirms that step
+bunching is induced by the particle advection caused by step-flow anisotropy.
+This anisotropy becomes important when due to the low Schwoebel barrier both
+sides of step are symmetric. Simulations show that in the opposite limit of
+very high Schwoebel barrier steps fracture and rough surface builds up.",1203.0194v1
+2012-03-01,Revisiting Cosmic No-Hair Theorem for Inflationary Settings,"In this work we revisit Wald's cosmic no-hair theorem in the context of
+accelerating Bianchi cosmologies for a generic cosmic fluid with non-vanishing
+anisotropic stress tensor and when the fluid energy momentum tensor is of the
+form of a cosmological constant term plus a piece which does not respect strong
+or dominant energy conditions. Such a fluid is the one appearing in
+inflationary models. We show that for such a system anisotropy may grow, in
+contrast to the cosmic no-hair conjecture. In particular, for a generic
+inflationary model we show that there is an upper bound on the growth of
+anisotropy. For slow-roll inflationary models our analysis can be refined
+further and the upper bound is found to be of the order of slow-roll
+parameters. We examine our general discussions and our extension of Wald's
+theorem for three classes of slow-roll inflationary models, generic
+multi-scalar field driven models, anisotropic models involving U(1) gauge
+fields and the gauge-flation scenario.",1203.0219v2
+2012-03-01,Parity Violating Statistical Anisotropy,"Particle production of an Abelian vector boson field with an axial coupling
+is investigated. The conditions for the generation of scale invariant spectra
+for the vector field transverse components are obtained. If the vector field
+contributes to the curvature perturbation in the Universe, scale-invariant
+particle production enables it to give rise to statistical anisotropy in the
+spectrum and bispectrum of cosmological perturbations. The axial coupling
+allows particle production to be parity violating, which in turn can generate
+parity violating signatures in the bispectrum. The conditions for parity
+violation are derived and the observational signatures are obtained in the
+context of the vector curvaton paradigm. Two concrete examples are presented
+based on realistic particle theory.",1203.0230v3
+2012-03-02,Investigation of Optical Spin Transfer Torque in Ferromagnetic Semiconductor GaMnAs by Magneto-Optical Pump-and-Probe Method,"We report on magnetization precession induced in (Ga,Mn)As by an optical spin
+transfer torque (OSTT). This phenomenon, which corresponds to a transfer of
+angular momentum from optically-injected spin-polarized electrons to
+magnetization, was predicted theoretically in 2004 and observed experimentally
+by our group in 2012. In this paper we provide experimental details about the
+observation of OSTT by a time-resolved pump-and-probe magneto-optical
+technique. In particular, we show that the precession of magnetization due to
+OSTT can be experimentally separated from that induced by the well known
+magnetic-anisotropy-related mechanism in a hybrid structure
+piezo-stressor/(Ga,Mn)As with an in situ electrical control of the magnetic
+anisotropy. We also illustrate that OSTT is clearly apparent in the measured
+dynamical magneto-optical signal in a large variety of (Ga,Mn)As samples with a
+Mn concentration from 3% to 9%.",1203.0483v1
+2012-03-12,Spin gating electrical current,"We use an aluminium single electron transistor with a magnetic gate to
+directly quantify the chemical potential anisotropy of GaMnAs materials.
+Uniaxial and cubic contributions to the chemical potential anisotropy are
+determined from field rotation experiments. In performing magnetic field sweeps
+we observe additional isotropic magnetic field dependence of the chemical
+potential which shows a non-monotonic behavior. The observed effects are
+explained by calculations based on the $\mathbf{k}\cdot\mathbf{p}$ kinetic
+exchange model of ferromagnetism in GaMnAs. Our device inverts the conventional
+approach for constructing spin transistors: instead of spin-transport
+controlled by ordinary gates we spin-gate ordinary charge transport.",1203.2439v2
+2012-03-19,A survey of lens spaces and large-scale CMB anisotropy,"The cosmic microwave background (CMB) anisotropy possesses the remarkable
+property that its power is strongly suppressed on large angular scales. This
+observational fact can naturally be explained by cosmological models with a
+non-trivial topology. The paper focuses on lens spaces L(p,q) which are
+realised by a tessellation of the spherical 3-space S^3 by cyclic deck groups
+of order p<=72. The investigated cosmological parameter space covers the
+interval Omega_tot \in [1.001,1.05]. Several spaces are found which have CMB
+correlations on angular scales theta >= 60^\circ suppressed by a factor of two
+compared to the simply connected S^3 space. The analysis is based on the S
+statistics, and a comparison to the WMAP 7yr data is carried out. Although the
+CMB suppression is less pronounced than in the Poincare dodecahedral space,
+these lens spaces provide an alternative worth for follow-up studies.",1203.4086v2
+2012-03-19,Anisotropy induced Feshbach resonances in a quantum dipolar gas of magnetic atoms,"We explore the anisotropic nature of Feshbach resonances in the collision
+between ultracold magnetic submerged-shell dysprosium atoms, which can only
+occur due to couplings to rotating bound states. This is in contrast to
+well-studied alkali-metal atom collisions, where most Feshbach resonances are
+hyperfine induced and due to rotation-less bound states. Our novel
+first-principle coupled-channel calculation of the collisions between
+open-4f-shell spin-polarized bosonic dysprosium reveals a striking correlation
+between the anisotropy due to magnetic dipole-dipole and electrostatic
+interactions and the Feshbach spectrum as a function of an external magnetic
+field. Over a 20 mT magnetic field range we predict about a dozen Feshbach
+resonances and show that the resonance locations are exquisitely sensitive to
+the dysprosium isotope.",1203.4172v1
+2012-03-22,Enhanced anisotropic spin fluctuations below tetragonal-to-orthorhombic transition in LaFeAs(O_{1-x}F_x) probed by ^{75}As and ^{139}La NMR,"$^{75}$As and $^{139}$La NMR results of LaFeAs(O$_{1-x}$F$_x$) ($x$=0, 0.025,
+and 0.04) were reported. Upon F-doping, the tetragonal-to-orthorhombic
+structural phase transition temperature $T_S$, antiferromagnetic transition
+temperature $T_N$ and internal magnetic field $\mu_0H_{\rm int}$ are gradually
+reduced for $x<0.04$. However, at $x=0.04$, $T_N$ is abruptly suppressed to be
+30 K along with a tiny $\mu_0H_{\rm int}$, which is distinct from the
+continuous disappearance of the ordered phases in the Ba122 systems of
+Ba(Fe,Co)$_2$As$_2$ and BaFe$_2$(As,P)$_2$. The anisotropy of the spin-lattice
+relaxation rate $T_1^{-1}$, $(T_1)^{-1}_{H\parallel ab}/(T_1)^{-1}_{H\parallel
+c}$, in the paramagnetic phase of $x = 0$ and 0.025 is constant ($\sim 1.5$),
+but increases abruptly below $T_S$ due to the enhancement of
+$(T_1)^{-1}_{H\parallel ab}$ by the slowing down of magnetic fluctuations. This
+indicates that the tetragonal-to-orthorhombic structural distortion enhances
+the anisotropy in the spin space via magnetoelastic coupling and/or spin-orbit
+interaction.",1203.4937v1
+2012-03-22,Pair density waves and vortices in an elongated two-component Fermi gas,"We study the vortex structures of a two-component Fermi gas experiencing a
+uniform effective magnetic field in an anisotropic trap that interpolates
+between quasi-one dimensional (1D) and quasi-two dimensional (2D). At a fixed
+chemical potential, reducing the anisotropy (or equivalently increasing the
+attractive interactions or increasing the magnetic field) leads to
+instabilities towards pair density waves, and vortex lattices. Reducing the
+chemical potential stabilizes the system. We calculate the phase diagram, and
+explore the density and pair density. The structures are similar to those
+predicted for superfluid Bose gases. We further calculate the paired fraction,
+showing how it depends on chemical potential and anisotropy.",1203.5120v1
+2012-03-29,Superconducting critical field far above the Pauli limit in one-dimensional Li$_{0.9}$Mo$_6$O$_{17}$,"The upper critical field $H_{c2}$ of purple bronze Li$_{0.9}$Mo$_6$O$_{17}$
+is found to exhibit a large anisotropy, in quantitative agreement with that
+expected from the observed electrical resistivity anisotropy. With the field
+aligned along the most conducting axis, $H_{c2}$ increases monotonically with
+decreasing temperature to a value five times larger than the estimated
+paramagnetic pair-breaking field. Theories for the enhancement of $H_{c2}$
+invoking spin-orbit scattering or strong-coupling superconductivity are shown
+to be inadequate in explaining the observed behavior, suggesting that the
+pairing state in Li$_{0.9}$Mo$_6$O$_{17}$ is unconventional and possibly
+spin-triplet.",1203.6672v1
+2012-04-01,Reconstruction of a Nonminimal Coupling Theory with Scale-invariant Power Spectrum,"A nonminimal coupling single scalar field theory, when transformed from
+Jordan frame to Einstein frame, can act like a minimal coupling one. Making use
+of this property, we investigate how a nonminimal coupling theory with
+scale-invariant power spectrum could be reconstructed from its minimal coupling
+counterpart, which can be applied in the early universe. Thanks to the coupling
+to gravity, the equation of state of our universe for a scale-invariant power
+spectrum can be relaxed, and the relation between the parameters in the action
+can be obtained. This approach also provides a means to address the Big-Bang
+puzzles and anisotropy problem in the nonminimal coupling model within Jordan
+frame. Due to the equivalence between the two frames, one may be able to find
+models that are free of the horizon, flatness, singularity as well as
+anisotropy problems.",1204.0189v2
+2012-04-02,A needlet ILC analysis of WMAP 9-year polarisation data: CMB polarisation power spectra,"We estimate Cosmic Microwave Background (CMB) polarisation power spectra, and
+temperature-polarisation cross-spectra, from the 9-year data of the Wilkinson
+Microwave Anisotropy Probe (WMAP). Foreground cleaning is implemented using
+minimum variance linear combinations of the coefficients of needlet
+decompositions of sky maps for all WMAP channels, to produce maps for CMB
+temperature anisotropies (T-mode) and polarisation (E-mode and B-mode), for 9
+different years of observation. The final power spectra are computed from
+averages of all possible cross-year power spectra obtained using
+foreground-cleaned maps for the different years. Our analysis technique yields
+a measurement of the EE spectrum that is in excellent agreement with
+theoretical expectations from the current cosmological model. By comparison,
+the publicly available WMAP EE power spectrum is higher on average (and
+significantly higher than the predicted EE spectrum from the current best fit)
+at scales larger than about a degree, an excess that is not confirmed by our
+analysis.",1204.0292v2
+2012-04-10,In-plane magnetic field anisotropy of the FFLO state in layered superconductors,"There are strong experimental evidences of the
+Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state formation in layered organic
+superconductors in parallel magnetic field. We study theoretically the
+interplay between the orbital effect and the FFLO modulation in this case and
+demonstrate that the in-plane critical field anisotropy drastically changes at
+the transition to the FFLO state. The very peculiar angular dependence of the
+superconducting onset temperature which is predicted may serve for unambiguous
+identification of the FFLO modulation. The obtained results permit us to
+suggest the modulated phase stabilization as the origin of the magnetic-field
+angle dependence of the onset of superconductivity experimentally observed in
+(TMTSF)$_{2}$ClO$_{4}$ organic conductors.",1204.2287v1
+2012-04-12,Highly-anisotropic hydrodynamics in 3+1 space-time dimensions,"Recently formulated model of highly-anisotropic and strongly dissipative
+hydrodynamics is used in 3+1 dimensions to study behavior of matter produced in
+ultra-relativistic heavy-ion collisions. We search for possible effects of the
+initial high anisotropy of pressure on the final soft-hadronic observables. We
+find that by appropriate adjustment of the initial energy density and/or the
+initial pseudorapidity distributions, the effects of the initial anisotropy of
+pressure may be easily compensated and the final hadronic observables become
+insensitive to early dynamics. Our results indicate that the early
+thermalization assumption is not necessary to describe hadronic data, in
+particular, to reproduce the measured elliptic flow v_2. The complete
+thermalization of matter (local equilibration) may take place only at the times
+of about 1-2 fm/c, in agreement with the results of microscopic models.",1204.2624v1
+2012-04-19,High intergrain critical current density in fine-grain (Ba0.6K0.4)Fe2As2 wires and bulks,"The K- and Co-doped BaFe2As2 (Ba-122) superconducting compounds are
+potentially useful for applications because they have upper critical fields
+(Hc2) of well over 50 T, Hc2 anisotropy Gamma < 2, and thin film critical
+current densities exceeding 1 MAcm-2 at 4.2 K. However, thin-film bicrystals of
+Co-doped Ba-122 clearly exhibit weak link behavior for [001] tilt
+misorientations of more than about 5 degrees, suggesting that textured
+substrates would be needed for applications, as in the cuprates. Here we
+present a contrary and very much more positive result in which untextured
+polycrystalline (Ba0.6K0.4)Fe2As2 bulks and round wires with high grain
+boundary density have transport critical current densities well over 0.1 MAcm-2
+(SF, 4.2 K), more than 10 times higher than that of any other ferropnictide
+wire. The enhanced grain connectivity is ascribed to their much improved phase
+purity and to the enhanced vortex stiffness of this low-anisotropy compound
+(Gamma ~ 1-2) compared to YBa2Cu3O7-x (Gamma ~ 5).",1204.4426v3
+2012-04-22,Scanning Tunneling Microscopy/Spectroscopy of Vortices in LiFeAs,"We investigate vortices in LiFeAs using scanning tunneling
+microscopy/spectroscopy. Zero-field tunneling spectra show two superconducting
+gaps without detectable spectral weight near the Fermi energy, evidencing
+fully-gapped multi-band superconductivity. We image vortices in a wide field
+range from 0.1 T to 11 T by mapping the tunneling conductance at the Fermi
+energy. A quasi-hexagonal vortex lattice at low field contains domain
+boundaries which consist of alternating vortices with unusual coordination
+numbers of 5 and 7. With increasing field, the domain boundaries become
+ill-defined, resulting in a uniformly disordered vortex matter. Tunneling
+spectra taken at the vortex center are characterized by a sharp peak just below
+the Fermi energy, apparently violating particlehole symmetry. The image of each
+vortex shows energy-dependent 4-fold anisotropy which may be associated with
+the anisotropy of the Fermi surface. The vortex radius shrinks with decreasing
+temperature and becomes smaller than the coherence length estimated from the
+upper critical field. This is direct evidence of the Kramer-Pesch effect
+expected in a clean superconductor.",1204.4863v1
+2012-04-26,Anisotropic flows from colour strings: Monte-Carlo simulations,"By direct Monte-Carlo simulations it is shown that the anisotropic flows can
+be successfully described in the colour string picture with fusion and
+percolation provided anisotropy of particle emission from the fused string is
+taken into account. Quenching of produced particles in the strong colour field
+of the string is the basic mechanism for this anisotropy. The concrete
+realization of this mechanism is borrowed from the QED. Due to dependence of
+this mechanism on the external field strength the found flows grow with energy,
+with values for $v_2$ at LHC energies greater by ~15% than at RHIC energies.",1204.5829v2
+2012-05-01,On geometry-dependent vortex stability and topological spin excitations on curved surfaces with cylindrical symmetry,"We study the Heisenberg Model on cylindrically symmetric curved surfaces. Two
+kinds of excitations are considered. The first is given by the isotropic
+regime, yielding the sine-Gordon equation and $\pi$-solitons are predicted. The
+second one is given by the XY model, leading to a vortex turning around the
+surface. Helical states are also considered, however, topological arguments can
+not be used to ensure its stability. The energy and the anisotropy parameter
+which stabilizes the vortex state are explicitly calculated for two surfaces:
+catenoid and hyperboloid. The results show that the anisotropy and the vortex
+energy depends on the underlying geometry.",1205.0287v5
+2012-05-02,Enhanced magnetic anisotropy of Nickel nanosheet prepared in Na-4 mica,"Nanosheets of nickel with thickness equal to 0.6 nm have been grown within
+the interlayer spaces of Na-4 mica. The sheets are made up of percolative
+clusters of nanodisks. Magnetization characteristics indicate a
+superparamagnetic behavior with a blocking temperature of 428 K.The magnetic
+anisotropy constant as extracted from the coercivity data has been found to be
+higher than that of bulk nickel by two orders of magnitude. This is ascribed to
+a large aspect ratio of the nickel nanophase. The Bloch exponent is also found
+to be considerably different from that of bulk nickel because of a size effect.
+The Bloch Equation is still found to be valid for the two dimensional
+structures.",1205.0405v1
+2012-05-03,Interpreting Magnetic Variance Anisotropy Measurements in the Solar Wind,"The magnetic variance anisotropy ($\mathcal{A}_m$) of the solar wind has been
+used widely as a method to identify the nature of solar wind turbulent
+fluctuations; however, a thorough discussion of the meaning and interpretation
+of the $\mathcal{A}_m$ has not appeared in the literature. This paper explores
+the implications and limitations of using the $\mathcal{A}_m$ as a method for
+constraining the solar wind fluctuation mode composition and presents a more
+informative method for interpreting spacecraft data. The paper also compares
+predictions of the $\mathcal{A}_m$ from linear theory to nonlinear turbulence
+simulations and solar wind measurements. In both cases, linear theory compares
+well and suggests the solar wind for the interval studied is dominantly
+Alfv\'{e}nic in the inertial and dissipation ranges to scales $k \rho_i \simeq
+5$.",1205.0749v1
+2012-05-11,Cosmic Microwave and Infrared Backgrounds cross-correlation for ISW detection,"We investigate the cross-correlation between the cosmic infrared and
+microwave backgrounds (CIB & CMB) anisotropies through the integrated
+Sachs-Wolfe effect. We first describe the CIB anisotropies using a linearly
+biased power spectrum, then derive the theoretical angular power spectrum of
+the CMB-CIB cross-correlation for different instruments and frequencies. We
+discuss the detectability of the ISW signal by performing a signal-to-noise
+(SNR) analysis with our predicted spectra. The significances obtained range
+from 6{\sigma} to 7{\sigma} in an ideal case, depending on the frequency ; in
+realistic cases which account for the presence of noise including astrophysical
+contaminants, the results span the range 2-5{\sigma}, depending strongly on the
+major contribution to the noise term.",1205.2537v1
+2012-05-16,"Piezoelectric strain induced variation of the magnetic anisotropy in a high Curie temperature (Ga,Mn)As sample","We show that effective electrical control of the magnetic properties in the
+ferromagnetic semiconductor (Ga,Mn)As is possible using the strain induced by a
+piezoelectric actuator even in the limit of high doping levels and high Curie
+temperatures, where direct electric gating is not possible. We demonstrate very
+large and reversible rotations of the magnetic easy axis. We compare the
+results obtained from magneto-transport and SQUID magnetometry measurements,
+extracting the dependence of the piezo-induced uniaxial magnetic anisotropy
+constant upon strain in both cases and detailing the limitations encountered in
+the latter approach.",1205.3725v1
+2012-05-21,Charge Multiplicity Asymmetry Correlation Study Searching for Local Parity Violation at RHIC for STAR,"It has been suggested that local parity violation in QCD would lead to charge
+separation of quarks by the Chiral Magnetic Effect (CME) in heavy ion
+collisions. Charge separation could yield a dynamical charge multiplicity
+asymmetry with respect to the reaction plane. In this talk, we report results
+on charge multiplicity asymmetry correlations in $\sqrt{s_{NN}}$ = 200 GeV
+Au+Au and d+Au collisions by the STAR experiment, as well as from the RHIC beam
+energy scan. We found that the correlation results could not be explained by
+CME alone. To gain further insights, we study our results as a function of the
+measured azimuthal angle range as well as the event-by-event anisotropy
+parameter $v_2$. The results indicate that the charge separation effect appears
+to be in-plane rather than out-of-plane. We found that the charge separation
+effect is proportional to the event-by-event $v_2$ and consistent with zero in
+events with $v_2 \approx 0$. Our studies suggest that the charge separation
+effect, within the statistical error, may be a net effect of event anisotropy
+and correlated particle production. Possible upper limit on the CME imposed by
+our data will be discussed.",1205.4638v1
+2012-05-21,Probing Two Holographic Models of Strongly Coupled Anisotropic Plasma,"Quark-gluon plasma during its initial phase after its production in heavy-ion
+collisions is expected to have substantial pressure anisotropies. In order to
+model this situation by a strongly coupled N=4 super-Yang-Mills plasma with
+fixed anisotropy by means of AdS/CFT duality, two models have been discussed in
+the literature. Janik and Witaszczyk have considered a geometry involving a
+comparatively benign naked singularity, while more recently Mateos and
+Trancanelli have used a regular geometry involving a nontrivial axion field
+dual to a parity-odd deformation of the gauge theory by a spatially varying
+theta parameter. We study the (rather different) implications of these two
+models on the heavy-quark potential as well as jet quenching and compare their
+respective predictions with those of weakly coupled anisotropic plasmas.",1205.4684v2
+2012-05-22,How to remedy the eta-problem of SUSY GUT hybrid inflation via vector backreaction,"It is shown that, in supergravity models of inflation where the gauge kinetic
+function of a gauge field is modulated by the inflaton, we can obtain a new
+inflationary attractor solution, in which the roll-over of the inflaton suffers
+additional impedance due to the vector field backreaction. As a result,
+directions of the scalar potential which, due to strong Kaehler corrections,
+become too steep and curved to normally support slow-roll inflation can now
+naturally do so. This solves the infamous eta-problem of inflation in
+supergravity and also keeps the spectral index of the curvature perturbation
+mildly red despite eta of order unity. This mechanism is applied to a model of
+hybrid inflation in supergravity with a generic Kaehler potential. The spectral
+index of the curvature perturbation is found to be 0.97 - 0.98, in excellent
+agreement with data. The gauge field can act as vector curvaton generating
+statistical anisotropy in the curvature perturbation. However, this anisotropy
+could be possibly observable only if the gauge coupling constant is unnaturally
+small.",1205.4830v1
+2012-05-29,Spin excitations in K$_{2}$Fe$_{4+x}$Se$_{5}$: linear response approach,"Using \emph{ab initio} linear response techniques we calculate spin wave
+spectra in K$_{2}$Fe$_{4+x}$Se$_{5}$, and find it to be in excellent agreement
+with a recent experiment. The spectrum can be alternatively described rather
+well by localized spin Hamiltonian restricted to first and second nearest
+neighbor couplings. We confirm that exchange coupling between nearest neighbor
+Fe magnetic moments is strongly anisotropic, and show directly that in the
+ideal system this anisotropy has itinerant nature which can be imitated by
+introducing higher order terms in effective localized spin Hamiltonian
+(biquadratic coupling). In the real system, structural relaxation provides an
+additional source of the exchange anisotropy of approximately the same
+magnitude. The dependence of spin wave spectra on filling of Fe vacancy sites
+is also discussed.",1205.6404v1
+2012-05-30,Continuous Move From BTW to Manna Model,"In the present paper we consider the BTW model perturbed by random-direction
+anisotropy with strength factor \epsilon ranging from 0 to 1 corresponding to
+BTW and Manna model receptively and investigate the properties of the
+statistical observables for various rates of anisotropy. By increasing the
+\epsilon, we observe a cross-over taking place between these models. For small
+length scales, the curves show properties similar to the BTW model whereas in
+the Infra red limit the corresponding \kappa is nearly the same as the Manna
+model. The observations confirm that this perturbation is relevant for the BTW
+fixed point and the infra red limit of the perturbed model is described by the
+Manna model. We also propose a differential equation whose solution properly
+fits with the the Green's function obtained by the simulation. This can help us
+to obtain the action of the perturbed model.",1205.6645v1
+2012-05-30,Unified decoupling scheme for exchange and anisotropy contributions and temperature-dependent spectral properties of anisotropic spin systems,"We compute the temperature-dependent spin-wave spectrum and the magnetization
+for a spin system using the unified decoupling procedure for the high-order
+Green's functions for the exchange coupling and anisotropy, both in the
+classical and quantum case. Our approach allows us to establish a clear
+crossover between quantum-mechanical and classical methods by developing the
+classical analog of the quantum Green's function technique. The results are
+compared with the classical spectral density method and numerical modeling
+based on the stochastic Landau-Lifshitz equation and the Monte Carlo technique.
+As far as the critical temperature is concerned, there is a full agreement
+between the classical Green's functions technique and the classical spectral
+density method. However, the former method turns out to be more straightforward
+and more convenient than the latter because it avoids any \emph{a priori}
+assumptions about the system's spectral density. The temperature-dependent
+exchange stiffness as a function of magnetization is investigated within
+different approaches.",1205.6646v1
+2012-05-30,Tunable Charge and Spin Seebeck Effects in Magnetic Molecular Junctions,"We study the charge and spin Seebeck effects in a spin-1 molecular junction
+as a function of temperature (T), applied magnetic field (H), and magnetic
+anisotropy (D) using Wilson's numerical renormalization group. A hard-axis
+magnetic anisotropy produces a large enhancement of the charge Seebeck
+coefficient Sc (\sim k_B/|e|) whose value only depends on the residual
+interaction between quasiparticles in the low temperature Fermi-liquid regime.
+In the underscreened spin-1 Kondo regime, the high sensitivity of the system to
+magnetic fields makes it possible to observe a sizable value for the spin
+Seebeck coefficient even for magnetic fields much smaller than the Kondo
+temperature. Similar effects can be obtain in C60 junctions where the control
+parameter is the gap between a singlet and a triplet molecular state.",1205.6759v1
+2012-06-04,Electrostatically Controlled Magnetization Rotation in Ferromagnet-Topological Insulator Planar Structures,"An approach to the electrostatic control of $90^{\circ}$ magnetization
+rotation in the hybrid structures composed of topological insulators (TIs) and
+adjacent ferromagnetic insulators (FMI) is proposed and studied. The concept is
+based on TI electron energy variation with in-plane to put-of plane FMI
+magnetization turn. The calculations explicitly expose the effect of free
+energy variability in the form of the electrically controlled uniaxial magnetic
+anisotropy, which depends on proximate exchange interaction and TI surface
+electron density. Combining with inherent anisotropy, the magnetization
+rotation from in-plane to out-of-plane direction is shown to be realizable for
+1.7~2.7 ns under the electrical variation of TI chemical potential in the range
+$\pm$ 100 meV around Dirac point. When bias is withdrawn a small signal current
+can target the out-of-plane magnetization instable state to the desirable
+direction of in-plane easy axis, thus the structure can lay the foundation for
+low energy nonvolatile memory prototype.",1206.0776v1
+2012-06-05,Spin-Orbit Coupling in LaAlO$_3$/SrTiO$_3$ interfaces: Magnetism and Orbital Ordering,"The combination of Rashba spin-orbit coupling and electron correlations can
+induce unusual phenomena in the metallic interface between SrTiO$_3$ and
+LaAlO$_3$. We consider effects of Rashba spin-orbit coupling at this interface
+in the context of the recent observation of anisotropic magnetism. Firstly, we
+show how Rashba spin-orbit coupling in a system near a band-edge can account
+for the observed magnetic anisotropy. Secondly, we investigate the coupling
+between in-plane magnetic-moment anisotropy and nematicity in the form of an
+orbital imbalance between d$_{xz}$ / d$_{yz}$ orbitals. We estimate this
+coupling to be substantial in the low electron density regime. Such an orbital
+ordering can affect magneto transport.",1206.1060v2
+2012-06-06,Preliminary Investigation of the Frictional Response of Reptilian Shed Skin,"Developing deterministic surfaces relies on controlling the structure of the
+rubbing interface so that not only the surface is of optimized topography, but
+also is able to self-adjust its tribological behaviour according to the
+evolution of sliding conditions. In seeking inspirations for such designs, many
+engineers are turning toward the biological world to correlate surface
+structure to functional behavior of bio-analogues. From a tribological point of
+view, squamate reptiles offer diverse examples where surface texturing,
+submicron and nano-scale features, achieve frictional regulation. In this
+paper, we study the frictional response of shed skin obtained from a snake
+(Python regius). The study employed a specially designed tribo-acoustic probe
+capable of measuring the coefficient of friction and detecting the acoustical
+behavior of the skin in vivo. The results confirm the anisotropy of the
+frictional response of snakes. The coefficient of friction depends on the
+direction of sliding: the value in forward motion is lower than that in the
+backward direction. In addition it is shown that the anisotropy of the
+frictional response may stem from profile asymmetry of the individual fibril
+structures present within the ventral scales of the reptile",1206.1153v1
+2012-06-07,Magnetic particle hyperthermia: Power losses under circularly polarized field in anisotropic nanoparticles,"The deterministic Landau-Lifshitz-Gilbert equation has been used to
+investigate the nonlinear dynamics of magnetization and the specific loss power
+in magnetic nanoparticles with uniaxial anisotropy driven by a rotating
+magnetic field, generalizing the results obtained for the isotropic case found
+in [P. F. de Chatel, I. Nandori, J. Hakl, S. Meszaros and K. Vad, J. Phys.:
+Condens. Matter 21, 124202 (2009)]. As opposed to many applications of
+magnetization reversal in single-domain ferromagnetic particles where losses
+must be minimized, in this paper, we study the mechanisms of dissipation used
+in cancer therapy by hyperthermia which requires the enhancement of energy
+losses. We show that for circularly polarized field, the loss energy per cycle
+is decreased by the anisotropy compared to the isotropic case when only
+dynamical effects are taken into account. Thus, in this case, in the low
+frequency limit, a better heating efficiency can be achieved for isotropic
+nanoparticles. The possible role of thermal fluctuations is also discussed.
+Results obtained are compared to experimental data.",1206.1544v2
+2012-06-18,Thermoelectric transport in $\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3$ superlattices,"The thermoelectric transport properties of
+$\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3$superlattices are analyzed on
+the basis of first-principles calculations and semi-classical Boltzmann theory.
+The anisotropy of the thermoelectric transport under electron and hole-doping
+was studied in detail for different superlattice periods at changing
+temperature and charge carrier concentrations. A clear preference for
+thermoelectric transport under hole-doping, as well as for the in-plane
+transport direction was found for all superlattice periods. At hole-doping the
+electrical transport anisotropies remain bulk-like for all investigated
+systems, while under electron-doping quantum confinement leads to strong
+suppression of the cross-plane thermoelectric transport at several superlattice
+periods. In addition, insights on the Lorenz function, the electronic
+contribution to the thermal conductivity and the resulting figure of merit are
+given.",1206.4078v1
+2012-06-19,Anisotropic magnetoresistance of bulk carbon nanotube sheets,"We have measured the magnetoresistance of stretched sheets of carbon
+nanotubes in temperatures ranging from 2 K to 300 K and in magnetic fields up
+to 9 T, oriented either perpendicular or parallel to the plane of the sheets.
+The samples have been partially aligned by post-fabrication stretching, such
+that the direction of stretching was either parallel or perpendicular to the
+direction of applied electric current. We have observed large differences
+between the magnetoresistance measured under the two field orientations, most
+pronounced at the lowest temperatures, highest fields, and for the
+laterally-aligned sample. Treatment of the sheets with nitric acid affects this
+anisotropy. We analyzed the results within the theoretical framework of weak
+and strong localization and concluded that the anisotropy bears the mark of a
+more unusual phenomenon, possibly magnetically-induced mechanical strain.",1206.4252v1
+2012-06-20,Spin Hall Conductivity on the Anisotropic Triangular Lattice,"We present a detailed study of the spin Hall conductivity on a
+two-dimensional triangular lattice in the presence of Rashba spin-orbit
+coupling. In particular, we focus part of our attention on the effect of the
+anisotropy of the nearest neighbor hopping amplitude. It is found that the
+presence of anisotropy has drastic effects on the spin Hall conductivity,
+especially in the hole doped regime where a significant increase or/and
+reversed sign of the spin Hall conductivity has been obtained. We also provide
+a systematic analysis of the numerical results in terms of Berry phases. The
+changes of signs observed at particular density of carriers appear to be a
+consequence of both Fermi surface topology and change of sign of electron
+velocity. In addition, in contrast to the two-dimensional square lattice, it is
+shown that the tight binding spin-orbit Hamiltonian should be derived carefully
+from the continuous model on the triangular lattice.",1206.4537v1
+2012-06-21,Late time anisotropy as an imprint of cosmological backreaction,"Backreaction effects of the large scale structure on the background dynamics
+have been claimed to lead to a renormalization of the background dynamics that
+may account for the late time acceleration of the cosmic expansion. This
+article emphasizes that generically the averaged flow is locally anisotropic, a
+property that can be related to observation. Focusing on perturbation theory,
+the spatially averaged shear, that characterizes the anisotropy of the flow, is
+computed. It is shown that this shear arising from backreaction differs from a
+homogeneous shear: its time evolution is different and its amplitude is
+completely determined by the cosmological parameters and the matter power
+spectrum. It ranges within (2-37)% at a redshift of order 0.5 so that the
+isotropy of the Hubble flow may allow to constrain the backreaction approach to
+dark energy.",1206.4887v3
+2012-06-21,Direct Observation of Massless Domain Wall Dynamics in Nanostripes with Perpendicular Magnetic Anisotropy,"Domain wall motion induced by nanosecond current pulses in nanostripes with
+perpendicular magnetic anisotropy (Pt/Co/AlO$_x$) is shown to exhibit
+negligible inertia. Time-resolved magnetic microscopy during current pulses
+reveals that the domain walls start moving, with a constant speed, as soon as
+the current reaches a constant amplitude, and no or little motion takes place
+after the end of the pulse. The very low 'mass' of these domain walls is
+attributed to the combination of their narrow width and high damping parameter
+$\alpha$. Such a small inertia should allow accurate control of domain wall
+motion, by tuning the duration and amplitude of the current pulses.",1206.4967v1
+2012-06-26,Temperature dependence of electronic transport through molecular magnets in the Kondo regime,"The effects of finite temperature in transport through nanoscopic systems
+exhibiting uniaxial magnetic anisotropy D, such as molecular magnets, adatoms,
+or quantum dots side-coupled to a large spin are analyzed in the Kondo regime.
+The linear-response conductance is calculated by means of the full
+density-matrix numerical renormalization group method as a function of
+temperature T, magnetic anisotropy D, and exchange coupling J between the
+molecule's core spin and the orbital level. It is shown that such system
+displays a two-stage Kondo effect as a function of temperature and a quantum
+phase transition as a function of the exchange coupling J. Moreover, additional
+peaks are found in the linear conductance for temperatures of the order of
+T\sim|J| and T\simD. It is also shown that the conductance variation with T
+remarkably depends on the sign of the exchange coupling J.",1206.6069v2
+2012-06-27,Theoretical Analysis of Electronic and Magnetic Properties of NaV$_2$O$_4$: Crucial Role of the Orbital Degrees of Freedom,"Using realistic low-energy model with parameters derived from the
+first-principles electronic structure calculation, we address the origin of the
+quasi-one-dimensional behavior in orthorhombic NaV$_2$O$_4$, consisting of the
+double chains of edge-sharing VO$_6$ octahedra. We argue that the geometrical
+aspect alone does not explain the experimentally observed anisotropy of
+electronic and magnetic properties of NaV$_2$O$_4$. Instead, we attribute the
+unique behavior of NaV$_2$O$_4$ to one particular type of the orbital ordering,
+which respects the orthorhombic $Pnma$ symmetry. This orbital ordering acts to
+divide all $t_{2g}$ states into two types: the `localized' ones, which are
+antisymmetric with respect to the mirror reflection $y \rightarrow -$$y$, and
+the symmetric `delocalized' ones. Thus, NaV$_2$O$_4$ can be classified as the
+double exchange system. The directional orientation of symmetric orbitals,
+which form the metallic band, appears to be sufficient to explain both
+quasi-one-dimensional character of interatomic magnetic interactions and the
+anisotropy of electrical resistivity.",1206.6525v1
+2012-06-28,Reentrant phase transitions and multicompensation points in the mixed-spin Ising ferrimagnet on a decorated Bethe lattice,"Mixed-spin Ising model on a decorated Bethe lattice is rigorously solved by
+combining the decoration-iteration transformation with the method of exact
+recursion relations. Exact results for critical lines, compensation
+temperatures, total and sublattice magnetizations are obtained from a precise
+mapping relationship with the corresponding spin-1/2 Ising model on a simple
+(undecorated) Bethe lattice. The effect of next-nearest-neighbour interaction
+and single-ion anisotropy on magnetic properties of the ferrimagnetic model is
+investigated in particular. It is shown that the total magnetization may
+exhibit multicompensation phenomenon and the critical temperature vs. the
+single-ion anisotropy dependence basically changes with the coordination number
+of the underlying Bethe lattice. The possibility of observing reentrant phase
+transitions is related to a high enough coordination number of the underlying
+Bethe lattice.",1206.6684v1
+2012-07-04,D3/D7 Quark-Gluon Plasma with Magnetically Induced Anisotropy,"We study the effects of the temperature and of a magnetic field in the setup
+of an intersection of D3/D7 branes, where a large number of D7 branes is
+smeared in the transverse directions to allow for a perturbative solution in a
+backreaction parameter. The magnetic field sources an anisotropy in the plasma,
+and we investigate its physical consequences for the thermodynamics and energy
+loss of particles probing the system. In particular we comment on the
+stress-energy tensor of the plasma, the propagation of sound in the directions
+parallel and orthogonal to the magnetic field, the drag force of a quark moving
+through the medium and jet quenching.",1207.1047v2
+2012-07-18,Cosmic Topology of Polyhedral Double-Action Manifolds,"A special class of non-trivial topologies of the spherical space S^3 is
+investigated with respect to their cosmic microwave background (CMB)
+anisotropies. The observed correlations of the anisotropies on the CMB sky
+possess on large separation angles surprising low amplitudes which might be
+naturally be explained by models of the Universe having a multiconnected
+spatial space. We analysed in CQG 29(2012)215005 the CMB properties of prism
+double-action manifolds that are generated by a binary dihedral group D^*_p and
+a cyclic group Z_n up to a group order of 180. Here we extend the CMB analysis
+to polyhedral double-action manifolds which are generated by the three binary
+polyhedral groups (T^*, O^*, I^*) and a cyclic group Z_n up to a group order of
+1000. There are 20 such polyhedral double-action manifolds. Some of them turn
+out to have even lower CMB correlations on large angles than the Poincare
+dodecahedron.",1207.4378v2
+2012-08-06,Event-plane decorrelation over pseudo-rapidity and its effect on azimuthal anisotropy measurement in relativistic heavy-ion collisions,"Within A Multi-Phase Transport model, we investigate decorrelation of event
+planes over pseudorapidity and its effect on azimuthal anisotropy measurements
+in relativistic heavy-ion collisions. The decorrelation increases with
+increasing {\eta} gap between particles used to reconstruct the event planes.
+The third harmonic event planes are found even anticorrelated between forward
+and backward rapidities, the source of which may root in the opposite
+orientation of the collision geometry triangularities. The decorrelation may
+call into question the anisotropic flow measurements with pseudorapidity gap
+designed to reduce nonflow contributions, hence the hydrodynamic properties of
+the quark-gluon plasma extracted from those measurements.",1208.1195v2
+2012-08-07,Anisotropic electrical resistivity of LaFeAsO: evidence for electronic nematicity,"Single crystals of LaFeAsO were successfully grown out of KI flux.
+Temperature dependent electrical resistivity was measured with current flow
+along the basal plane, \rho_perpend(T), as well as with current flow along the
+crystallographic c-axis, \rho_parallel(T), the latter one utilizing electron
+beam lithography and argon ion beam milling. The anisotropy ratio was found to
+lie between \rho_parallel/\rho_perpend = 20 - 200. The measurement of
+\rho_perpend(T) was performed with current flow along the tetragonal [1 0 0]
+direction and along the [1 1 0] direction and revealed a clear in-plane
+anisotropy already at T \leq 175 K. This is significantly above the
+orthorhombic distortion at T_0 = 147 K and indicates the formation of an
+electron nematic phase. Magnetic susceptibility and electrical resistivity give
+evidence for a change of the magnetic structure of the iron atoms from
+antiferromagnetic to ferromagnetic arrangement along the c-axis at T^\ast = 11
+K.",1208.1480v3
+2012-08-09,Electron-like Fermi surface and in-plane anisotropy due to chain states in YBa$_2$Cu$_3$O$_{7-δ}$ superconductors,"We present magneto-transport calculations for YBa$_2$Cu$_3$O$_{7-\delta}$
+(YBCO) materials to show that the electron-like metallic chain state gives both
+the negative Hall effect and in-plane anisotropic large Nernst signal. We show
+that the inevitable presence of the metallic 1D CuO chain layer lying between
+the CuO2 bilayers in YBCO renders an electron-like Fermi surface in the doping
+range as wide as p=0.05 to overdoping. With underdoping, a pseudogap opening in
+the CuO2 state reduces its hole-carrier contribution, and therefore the net
+electron-like quasiparticles dominate the transport properties, and a negative
+Hall resistance commences. We also show that the observation of in-plane
+anisotropy in the Nernst signal - which was taken as a definite evidence of the
+electronic `nematic' pseudogap phase - is naturally explained by including the
+`quasi-uniaxial' metallic chain state. Finally, we comment on how the chain
+state can also lead to electron-like quantum oscillations.",1208.1979v1
+2012-08-12,"UHECR bending, clustering and decaying feeding gamma anisotropy","Ultra High Cosmic Rays) made by He-like lightest nuclei might fit clustering
+along Cen A. Moreover He like UHECR nuclei explain Virgo absence because the
+light nuclei fragility and opacity above a few Mpc. We foresaw (2009) that
+UHECR He from Cen-A AGN being fragile should partially fragment into
+secondaries at tens EeV multiplet (D,He^{3},p) as the recent twin multiplet
+discovered ones (AUGER-ICRC-2011), at 20 EeV along Cen A UHECR clustering. We
+suggest that UHECR are also heavy radioactive galactic nuclei as Ni^{56},
+Ni^{57} and Co^{57} widely bent (tens degree up to 100 degrees) by galactic
+fields. UHECR radioactivity and decay in flight at hundreds keV is boosted (by
+huge Lorentz factor (billion) leading to PeVs electrons and consequent
+synchrotron TeVs gamma offering UHECR-TeV correlated sky anisotropy. Electron
+and tau neutrinos secondaries at PeVs maybe the first signature of such
+expected radioactive secondary tail.",1208.2471v1
+2012-08-15,Vortex lock-in transition coinciding with the 3D to 2D crossover in YBa2Cu3O7,"A vortex lock-in transition was directly detected by torque magnetometry in
+an overdoped YBa2Cu3O7 single crystal of low anisotropy (\approx 7). The
+locked-in state was observed below the 3D to 2D crossover temperature Tcr = 76
+K, independently of extrinsic pinning effects thanks to a high quality clean
+crystal and the use of a vortex shaking technique. The shape of the torque
+signal as a function of the angle between the applied magnetic field and the
+crystallographic c-axis is in very good agreement with the model developped by
+Feinberg and Ettouhami [Int. J. Mod. Phys. B 7, 2085 (1993)] for quasi-2D
+superconductors, despite the low anisotropy of the material.",1208.3062v1
+2012-08-15,Spin Triplet Supercurrent in Co/Ni Multilayer Josephson Junctions with Perpendicular Anisotropy,"We have measured spin-triplet supercurrent in Josephson junctions of the form
+S/F'/F/F'/S, where S is superconducting Nb, F' is a thin Ni layer with in-plane
+magnetization, and F is a Ni/[Co/Ni]n multilayer with out-of-plane
+magnetization. The supercurrent in these junctions decays very slowly with
+F-layer thickness, and is much larger than in similar junctions not containing
+the two F' layers. Those two features are the characteristic signatures of
+spin-triplet supercurrent, which is maximized by the orthogonality of the
+magnetizations in the F and F' layers. Magnetic measurements confirm the
+out-of-plane anisotropy of the Co/Ni multilayers. These samples have their
+critical current optimized in the as-prepared state, which will be useful for
+future applications.",1208.3118v1
+2012-08-17,Non-volatile voltage control of magnetization and magnetic domain walls in magnetostrictive epitaxial thin films,"We demonstrate reproducible voltage induced non-volatile switching of the
+magnetization in an epitaxial thin Fe81Ga19 film. Switching is induced at room
+temperature and without the aid of an external magnetic field. This is achieved
+by the modification of the magnetic anisotropy by mechanical strain induced by
+a piezoelectric transducer attached to the layer. Epitaxial Fe81Ga19 is shown
+to possess the favourable combination of cubic magnetic anisotropy and large
+magnetostriction necessary to achieve this functionality with experimentally
+accessible levels of strain. The switching of the magnetization proceeds by the
+motion of magnetic domain walls, also controlled by the voltage induced strain.",1208.3567v1
+2012-08-17,Percolation of linear $k$-mers on square lattice: from isotropic through partially ordered to completely aligned state,"Numerical simulations by means of Monte Carlo method and finite-size scaling
+analysis have been performed to study the percolation behavior of linear
+$k$-mers (also denoted in the literature as rigid rods, needles, sticks) on
+two-dimensional square lattices $L \times L$ with periodic boundary conditions.
+Percolation phenomena are investigated for anisotropic relaxation random
+sequential adsorption of linear $k$-mers. Especially, effect of anisotropic
+placement of the objects on the percolation threshold has been investigated.
+Moreover, the behavior of percolation probability $R_L(p)$ that a lattice of
+size $L$ percolates at concentration $p$ has been studied in details in
+dependence on $k$, anisotropy and lattice size $L$. A nonmonotonic size
+dependence for the percolation threshold has been confirmed in isotropic case.
+We propose a fitting formula for percolation threshold $p_c =
+a/k^{\alpha}+b\log_{10} k+ c$, where $a$, $b$, $c$, $\alpha$ are the fitting
+parameters varying with anisotropy. We predict that for large $k$-mers
+($k\gtrapprox 1.2\times10^4$) isotropic placed at the lattice, percolation
+cannot occur even at jamming concentration.",1208.3602v1
+2012-08-22,Anisotropy and effective dimensionality crossover of the fluctuation conductivity of hybrid superconductor/ferromagnet structures,"We study the fluctuation conductivity of a superconducting film, which is
+placed to perpendicular non-uniform magnetic field with the amplitude $H_0$
+induced by the ferromagnet with domain structure. The conductivity tensor is
+shown to be essentially anisotropic. The magnitude of this anisotropy is
+governed by the temperature and the typical width of magnetic domains $d$. For
+$d\ll L_{H_0}=\sqrt{\Phi_0/H_0}$ the difference between diagonal fluctuation
+conductivity components $\Delta\sigma_\parallel$ along the domain walls and
+$\Delta\sigma_\perp$ across them has the order of $(d/L_{H_0})^4$. In the
+opposite case for $d\gg L_{H_0}$ the fluctuation conductivity tensor reveals
+effective dimensionality crossover from standard two-dimensional $(T-T_c)^{-1}$
+behavior well above the critical temperature $T_c$ to the one-dimensional
+$(T-T_c)^{-3/2}$ one close to $T_c$ for $\Delta\sigma_\parallel$ or to the
+$(T-T_c)^{-1/2}$ dependence for $\Delta\sigma_\perp$. In the intermediate case
+$d\approx L_{H_0}$ for a fixed temperature shift from $T_c$ the dependence
+$\Delta\sigma_\parallel(H_0)$ is shown to have a minimum at $H_0\sim\Phi_0/d^2$
+while $\Delta\sigma_\perp(H_0)$ is a monotonically increasing function.",1208.4562v2
+2012-08-23,Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors,"The superconducting gap is the fundamental parameter that characterizes the
+superconducting state, and its symmetry is a direct consequence of the
+mechanism responsible for Cooper pairing. Here we discuss about angle-resolved
+photoemission spectroscopy measurements of the superconducting gap in the
+Fe-based high-temperature superconductors. We show that the superconducting gap
+is Fermi surface dependent and nodeless with small anisotropy, or more
+precisely, a function of momentum. We show that while this observation is
+inconsistent with weak coupling approaches for superconductivity in these
+materials, it is well supported by strong coupling models and global
+superconducting gaps. We also suggest that the strong anisotropies measured by
+other probes sensitive to the residual density of states are not related to the
+pairing interaction itself, but rather emerge naturally from the smaller
+lifetime of the superconducting Cooper pairs that is a direct consequence of
+the momentum dependent interband scattering inherent to these materials.",1208.4717v1
+2012-08-25,Spin dynamics of possible density wave states in the pseudogap phase of the high temperature superconductors,"In a recent inelastic neutron scattering experiment in the pseudogap state of
+the high temperature superconductor $\mathrm{YBa_{2}Cu_{3}O_{6.6}}$ an unusual
+`vertical' dispersion of the spin excitations with a large in-plane anisotropy
+was observed. In this paper we discuss in detail the spin susceptibility of the
+singlet $d$-density wave, the triplet $d$-density wave, as well as the more
+common spin density wave orders with hopping anisotropies. From numerical
+calculations within the framework of random phase approximation, we find nearly
+vertical dispersion relations for spin excitations with anisotropic
+incommensurability at low energy $\omega \le 90 meV$, which are reminiscent of
+the experiments. At very high energy $\omega \ge 165 meV$, we also find
+energy-dependent incommensurability. Although there are some important
+difference between the three cases, unpolarized neutron measurements cannot
+discriminate between these alternate possibilities; the vertical dispersion,
+however, is a distinct feature of all three density wave states in contrast to
+the superconducting state, which shows an hour-glass shape dispersion.",1208.5108v1
+2012-08-28,Magnetic field sensor with voltage-tunable sensing properties,"We report on a magnetic field sensor based on CoFeB/MgO/CoFeB magnetic tunnel
+junctions. By taking advantage of the perpendicular magnetic anisotropy of the
+CoFeB/MgO interface, the magnetization of the sensing layer is tilted
+out-of-plane which results in a linear response to in-plane magnetic fields.
+The application of a bias voltage across the MgO tunnel barrier of the field
+sensor affects the magnetic anisotropy and thereby its sensing properties. An
+increase of the maximum sensitivity and simultaneous decrease of the magnetic
+field operating range by a factor of two is measured. Based on these results,
+we propose a voltage-tunable sensor design that allows for active control of
+the sensitivity and the operating filed range with the strength and polarity of
+the applied bias voltage.",1208.5588v1
+2012-08-29,Electron spin resonance shifts in S=1 antiferromagnetic chains,"We discuss electron spin resonance (ESR) shifts in spin-1 Heisenberg
+antiferromagnetic chains with a weak single-ion anisotropy based on several
+effective field theories, the O(3) nonlinear sigma model (NLSM) in the Haldane
+phase, free fermion theories around the lower and the upper critical fields. In
+the O(3) NLSM, the single-ion anisotropy corresponds to a composite operator
+which creates two magnons at the same time and position. Therefore, even inside
+a parameter range where free magnon approximation is valid, we have to take
+interactions among magnons into account. Though the O(3) NLSM is only valid in
+the Haldane phase, an appropriate translation of Faddeev-Zamolodchikov
+operators of the O(3) NLSM to fermion operators enables one to treat ESR shifts
+near the lower critical field in a similar manner to discussions in Haldane
+phase. We present that our theory gives quantitative agreements with recent ESR
+experimental results on an spin-1 chain compounds NDMAP.",1208.6017v2
+2012-09-04,Magnetic and nematic orderings in spin-1 antiferromagnets with single-ion anisotropy,"We study a spin-one Heisenberg model with exchange interaction, J, uniaxial
+single-ion exchange anisotropy, D, and Zeeman coupling to a magnetic field, B,
+parallel to the symmetry axis. We com- pute the (D/J,B/J) quantum phase diagram
+for square and simple cubic lattices by combining an- alytical and Quantum
+Monte Carlo approaches, and find a transition between XY-antiferromagnetic and
+ferronematic phases that spontaneously break the U(1) symmetry of the model. In
+the language of bosonic gases, this is a transition between a Bose-Einstein
+condensate (BEC) of single bosons and a BEC of pairs. Our work opens up new
+avenues for measuring this transition in real magnets.",1209.0688v3
+2012-09-11,The role of pressure anisotropy in the turbulent intracluster medium,"In low-density plasma environments, such as the intracluster medium (ICM),
+the Larmour frequency is much larger than the ion-ion collision frequency. In
+such a case, the thermal pressure becomes anisotropic with respect to the
+magnetic field orientation and the evolution of the turbulent gas is more
+correctly described by a kinetic approach. A possible description of these
+collisionless scenarios is given by the so-called kinetic magnetohydrodynamic
+(KMHD) formalism, in which particles freely stream along the field lines, while
+moving with the field lines in the perpendicular direction. In this way a
+fluid-like behavior in the perpendicular plane is restored. In this work, we
+study fast growing magnetic fluctuations in the smallest scales which operate
+in the collisionless plasma that fills the ICM. In particular, we focus on the
+impact of a particular evolution of the pressure anisotropy and its
+implications for the turbulent dynamics of observables under the conditions
+prevailing in the ICM. We present results from numerical simulations and
+compare the results which those obtained using an MHD formalism.",1209.2302v1
+2012-09-23,CMB Anisotropy Due to Filamentary Gas: Power Spectrum and Cosmological Parameter Bias,"Hot gas in filamentary structures induces CMB aniostropy through the SZ
+effect. Guided by results from N-body simulations, we model the morphology and
+gas properties of filamentary gas and determine the power spectrum of the
+anisotropy. Our treatment suggests that power levels can be an appreciable
+fraction of the cluster contribution at multipoles $\ell\lesssim 1500$. Its
+spatially irregular morphology and larger characteristic angular scales can
+help to distinguish this SZ signature from that of clusters. In addition to
+intrinsic interest in this most extended SZ signal as a probe of filaments, its
+impact on cosmological parameter estimation should also be assessed. We find
+that filament `noise' can potentially bias determination of $A_s$, $n_s$, and
+$w$ (the normalization of the primordial power spectrum, the scalar index, and
+the dark energy equation of state parameter, respectively) by more than the
+nominal statistical uncertainty in Planck SZ survey data. More generally, when
+inferred from future optimal cosmic-variance-limited CMB experiments, we find
+that virtually all parameters will be biased by more than the nominal
+statistical uncertainty estimated for these next generation CMB experiments.",1209.5065v1
+2012-09-27,Identifying the Magnetoelectric Modes of Multiferroic BiFeO$_3$,"We have identified three of the four magnetoelectric modes of multiferroic
+BiFeO$_3$ measured using THz spectroscopy. Excellent agreement with the
+observed peaks is obtained by including the effects of easy-axis anisotropy
+along the direction of the electric polarization. By distorting the cycloidal
+spin state, anisotropy splits the $\Psi_{\pm 1}$ mode into peaks at 20 and 21.5
+cm$^{-1}$ and activates the lower $\Phi_{\pm 2}$ mode at 27 cm$^{-1}$ (T=200
+K). An electromagnon is identified with the upper $\Psi_{\pm 1}$ mode at 21.5
+cm$^{-1}$. Our results also explain recent Raman and inelastic
+neutron-scattering measurements.",1209.6244v1
+2012-09-28,Acoustic impedance and interface phonon scattering in Bi$_2$Te$_3$ and other semiconducting materials,"We present first principles calculations of the phonon dispersions of Bi2Te3
+and discuss these in relation to the acoustic phonon interface scattering in
+ceramics. The phonon dispersions show agreement with what is known from neutron
+scattering for the optic modes. We find a difference between the generalized
+gradient approximation and local density results for the acoustic branches.
+This is a consequence of an artificial compression of the van der Waals bonded
+gaps in the Bi2Te3 structure when using the generalized gradient approximation.
+As a result local density approximation calculations provide a better
+description of the phonon dispersions in Bi$_{2}$Te$_{3}$. A key characteristic
+of the acoustic dispersions is the existence of a strong anisotropy in the
+velocities. We develop a model for interface scattering in ceramics with
+acoustic wave anisotropy and apply this to Bi2Te3 and compare with PbTe and
+diamond.",1209.6555v1
+2012-10-03,Event-by-event azimuthal anisotropy of jet quenching in relativistic heavy ion collisions,"In this paper we present with full details a systematic quantification, on an
+even-by-event basis, of the hard probe response to the geometry and
+fluctuations of the hot QCD matter created in heavy ion collisions at both the
+Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The
+azimuthal anisotropy of jet quenching is extracted and decomposed as harmonic
+responses (for n=1,2,3,4,5,6) to the corresponding harmonics in the fluctuating
+initial condition. We show that such jet response harmonics are sensitive to
+the jet quenching models as well as to the bulk matter initial compositions. By
+studying these for all centralities at both RHIC and LHC energies we put a
+strong constraint on the path-length and medium-density dependence of jet
+energy loss. We also examine the hard-soft di-hadron correlation arising from
+the hard and soft sectors' responses to the common initial fluctuations. We
+demonstrate that the experimentally observed ""hard-ridge"" can be explained this
+way and that its dependence on the trigger-azimuthal-angle could also be
+qualitatively understood.",1210.1245v2
+2012-10-06,Bilayer Twisted Hubbard Model for Sr3Ir2O7,"We use the bilayer twisted Hubbard model to study the low energy electronic
+structure of Sr3Ir2O7. Sr3Ir2O7 is suggested as a Mott insulator and described
+by the bilayer twisted pseudospin-1/2 model. The bilayer twists in Sr3Ir2O7
+bring the intrinsic anisotropy and the system is no longer SU(2) invariant. The
+anisotropy selects an easy c-axis collinear antiferromagnetic magnetic
+structure at low temperatures which breaks the discrete Ising symmetry. The
+transverse spin excitations are gapped and the longitudinal one is weakly
+dispersive. We implement the bond-operator mean field calculation to describe
+the magnetic properties of the bilayer twisted pseudospin-1/2 model in good
+agreement with experimental measurements in Sr3Ir2O7. The bilayer twisted
+Hubbard model is believed to be the good zeroth approximation for the low
+energy electronic structure of Sr3Ir2O7.",1210.1974v1
+2012-10-10,An anisotropy preserving metric for DTI processing,"Statistical analysis of Diffusion Tensor Imaging (DTI) data requires a
+computational framework that is both numerically tractable (to account for the
+high dimensional nature of the data) and geometric (to account for the
+nonlinear nature of diffusion tensors). Building upon earlier studies that have
+shown that a Riemannian framework is appropriate to address these challenges,
+the present paper proposes a novel metric and an accompanying computational
+framework for DTI data processing. The proposed metric retains the geometry and
+the computational tractability of earlier methods grounded in the affine
+invariant metric. In addition, and in contrast to earlier methods, it provides
+an interpolation method which preserves anisotropy, a central information
+carried by diffusion tensor data.",1210.2826v1
+2012-10-10,Magnetic Vortex with Skyrmionic Core in Thin Nanodisk of the Chiral Magnets,"A type of vortex spin texture with skyrmionic core and a series of circle
+spin stripes was obtained in thin nanodisk of the chiral magnets with
+Dzyaloshinskii-Moriya interaction and uniaxial anisotropy by means of
+micromagnetic approach and Monte Carlo simulation. The size of skyrmionic core
+can be modulated continuously by controlling the disk size. Moreover, in some
+certain values of the disk size, this vortex state may be spontaneous ground
+state even without the help of the external magnetic field and thermal
+fluctuation. In addition, the uniaxial anisotropy is able to stabilize this
+vortex spin texture. We anticipate that the present work will inspire further
+experimental studies for exploring the spin structure.",1210.2862v2
+2012-10-13,Large scale distribution of arrival directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger Observatory,"A thorough search for large scale anisotropies in the distribution of arrival
+directions of cosmic rays detected above $10^{18}$ eV at the Pierre Auger
+Observatory is presented. This search is performed as a function of both
+declination and right ascension in several energy ranges above $10^{18}$ eV,
+and reported in terms of dipolar and quadrupolar coefficients. Within the
+systematic uncertainties, no significant deviation from isotropy is revealed.
+Assuming that any cosmic ray anisotropy is dominated by dipole and quadrupole
+moments in this energy range, upper limits on their amplitudes are derived.
+These upper limits allow us to challenge an origin of cosmic rays above
+$10^{18}$ eV from stationary galactic sources densely distributed in the
+galactic disk and emitting predominantly light particles in all directions.",1210.3736v2
+2012-10-17,The power-law spectra of energetic particles during multi-island magnetic reconnection,"Power-law distributions are a near universal feature of energetic particle
+spectra in the heliosphere. Anomalous Cosmic Rays (ACRs), super-Alfv\'enic ions
+in the solar wind and the hardest energetic electron spectra in flares all have
+energy fluxes with power-laws that depend on energy $E$ approximately as
+$E^{-1.5}$. We present a new model of particle acceleration in systems with a
+bath of merging magnetic islands that self-consistently describes the
+development of velocity-space anisotropy parallel and perpendicular to the
+local magnetic field and includes the self-consistent feedback of pressure
+anisotropy on the merging dynamics. By including pitch-angle scattering we
+obtain an equation for the omni-directional particle distribution $f(v,t)$ that
+is solved in closed form to reveal $v^{-5}$ (corresponding to an energy flux
+varying as $E^{-1.5}$) as a near-universal solution as long as the
+characteristic acceleration time is short compared with the characteristic loss
+time. In such a state the total energy in the energetic particles reaches
+parity with the remaining magnetic free energy. More generally, the resulting
+transport equation can serve as the basis for calculating the distribution of
+energetic particles resulting from reconnection in large-scale inhomogeneous
+systems.",1210.4830v1
+2012-10-18,Unstable dynamics of Yang-Mills fields at early times of heavy ion collisions,"The quark gluon plasma as produced in heavy ion collisions is exposed to
+early anisotropies in momentum space due to its rapid expansion. Such
+anisotropies can lead to non-abelian plasma instabilities, driven by unstable
+gluonic modes that can grow exponentially fast. These plasma instabilities can
+be simulated using a discretized version of gauge-covariant Boltzmann-Vlasov
+and Yang-Mills equations. In the stationary case, a turbulent cascade forms in
+the strong-field regime, which is associated with an approximately linear
+growth of energy in collective fields. Early longitudinal expansion slows down
+the growth of unstable modes, and the formation of soft gluonic fields depends
+crucially on the initial conditions assumed.",1210.5150v1
+2012-10-19,"Two-dimensional magnetism in kappa-(BEDT-TTF)2Cu[N(CN)2]Cl, a spin-1/2 Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interaction","Field-induced antiferromagnetic (AF) fluctuations and magnetization are
+observed above the (zero-field) ordering temperature, T_N = 23 K by electron
+spin resonance in kappa-(BEDT-TTF)_2Cu[N(CN)_2]Cl, a quasi two-dimensional
+antiferromagnet with a large isotropic Heisenberg exchange interaction. The
+Dzyaloshinskii-Moriya (DM) interaction is the main source of anisotropy, the
+exchange anisotropy and the interlayer coupling are very weak. The AF
+magnetization is induced by magnetic fields perpendicular to the DM vector;
+parallel fields have no effect. The different orientation of the DM vectors and
+the g factor tensors in adjacent layers allows the distinction between
+interlayer and intralayer correlations. Magnetic fields induce the AF
+magnetization independently in adjacent layers. We suggest that the phase
+transition temperature, T_N is determined by intralayer interactions alone.",1210.5381v1
+2012-10-19,Topological phases in ultracold polar-molecule quantum magnets,"We show how to use polar molecules in an optical lattice to engineer quantum
+spin models with arbitrary spin S >= 1/2 and with interactions featuring a
+direction-dependent spin anisotropy. This is achieved by encoding the effective
+spin degrees of freedom in microwave-dressed rotational states of the molecules
+and by coupling the spins through dipolar interactions. We demonstrate how one
+of the experimentally most accessible anisotropies stabilizes symmetry
+protected topological phases in spin ladders. Using the numerically exact
+density matrix renormalization group method, we find that these interacting
+phases -- previously studied only in the nearest-neighbor case -- survive in
+the presence of long-range dipolar interactions. We also show how to use our
+approach to realize the bilinear-biquadratic spin-1 and the Kitaev honeycomb
+models. Experimental detection schemes and imperfections are discussed.",1210.5518v2
+2012-10-22,CMB anisotropy science: a review,"The cosmic microwave background (CMB) provides us with our most direct
+observational window to the early universe. Observations of the temperature and
+polarization anisotropies in the CMB have played a critical role in defining
+the now-standard cosmological model. In this contribution we review some of the
+basics of CMB science, highlighting the role of observations made with
+ground-based and balloon-borne Antarctic telescopes. Most of the ingredients of
+the standard cosmological model are poorly understood in terms of fundamental
+physics. We discuss how current and future CMB observations can address some of
+these issues, focusing on two directly relevant for Antarctic programmes:
+searching for gravitational waves from inflation via B-mode polarization, and
+mapping dark matter through CMB lensing.",1210.6008v1
+2012-10-26,Directional vortex pinning at microwave frequency in YBa$_{2}$Cu$_3$O$_{7-x}$ thin films with BaZrO$_3$ nanorods,"We investigate the effect of the anisotropy and of the directional pinning in
+YBa$_2$Cu$_3$O$_{7-x}$ films grown by pulsed laser ablation from targets
+containing BaZrO$_3$ at 5% mol. BaZrO$_3$ inclusions self-assemble to give
+nanorods oriented along the c-axis, thus giving a preferential direction for
+vortex pinning. The directionality of vortex response is studied at high ac
+frequency with the complex microwave response at 48 GHz, as a function of the
+applied field and of the angle $\theta$ between the field and the c-axis. The
+complex microwave response does not exhibit any angular scaling, suggesting
+that the structural anisotropy of YBa$_2$Cu$_3$O$_{7-x}$ is supplemented by at
+least another preferred orientation. The pinning parameter $r$ shows evidence
+of directional pinning, effective in a wide range of angles around the c-axis
+(thus ascribed to BZO nanocolumns).",1210.7232v1
+2012-10-28,Bottomonia in the Quark Gluon Plasma,"I review recent calculations of the suppression of bottomonium states in
+heavy ion collisions. A non-relativistic potential is used which is complex
+valued. This allows one to extract the binding energies and decay widths of the
+ground and excited states of bottomonium as a function of the typical plasma
+particle momentum and momentum-space anisotropy. The decay widths determined
+are used as input and integrated over space-time taking into account the
+dynamical evolution of the typical particle momentum and momentum-space
+anisotropy. The suppression of Upsilon(1s), Upsilon(2s), Upsilon(3s), chi_b1,
+and chi_b2 is obtained as a function of centrality, rapidity, and transverse
+momentum. The obtained results are compared with data from the STAR and CMS
+collaborations.",1210.7512v1
+2012-10-30,Enhancement of Curie temperature due to the coupling between Fe itinerant electrons and Dy localized electrons in DyFe2Zn20,"The temperature dependence of magnetization and specific heat of the
+ferromagnetic compound DyFe2Zn20 has been measured in detail in various
+magnetic fields. We have observed anomalous magnetic behavior, i.e., a strong
+anisotropy at 2 K, disappearance of this anisotropy between approximately 30 K
+and T_c, and anomalous behavior of the specific heat in the magnetic fields
+near 20 K. These anomalous phenomena have been analyzed based on the strong
+exchange interaction between the Fe itinerant electrons and the Dy localized
+electrons as well as the crystalline electric field, Zeeman energy, and an
+usual exchange interaction between two Dy atoms. The higher T_c of DyFe2Zn20
+compared with that of DyRu2Zn20 is caused by this exchange interaction between
+the Fe and Dy atoms.",1210.7922v1
+2012-11-01,Dynamics of Dark Matter in Baryon-Radiation Plasma: Perspectives using Meschersky equation,"With an aim to argue for the truly collisionless nature of cold dark matter
+between epochs of equality and recombination, we assume a model, wherein
+strongly coupled baryon-radiation plasma ejects out of small regions of
+concentrated cold dark matter without losing its equilibrium. We use the
+Meschersky equation to describe the dynamics of cold dark matter in the
+presence of varying mass of strongly coupled baryon-radiation plasma. Based on
+this model, we discuss the growth of perturbations in cold dark matter both in
+the Jeans theory and in the expanding universe using Newton's theory. We see
+the effect of the perturbations in the cold dark matter potential on the cosmic
+microwave background anisotropy that originated at redshifts between equality
+and recombination i.e. $1100 < z < z_{eq}$. Also we obtain an expression for
+the Sachs-Wolfe effect, i.e. the CMB temperature anisotropy at decoupling in
+terms of the perturbations in cold dark matter potential. We obtain similar
+solutions both in the static and in the expanding universe, for epochs of
+recombination. From this, we infer about the time scale when the dark energy
+starts to dominate.",1211.0154v1
+2012-11-01,Metric emerging to massive modes in quantum cosmological space-times,"We consider a massive quantum test Klein-Gordon field probing an isotropic
+quantum cosmological space-time in the background. The result obtained is
+surprising. It turns out, that despite the isotropy of the quantum
+gravitational field, the semi-classical metric experienced by a mode of the K-G
+field is non-isotropic. The anisotropy depends on the direction of the momentum
+of the mode. Specifically, what we do is to derive a semi-classical space-time
+which emerges to a mode of the field. The method amounts to a comparison
+between QFT on a quantum background and QFT on a classical curved space-time,
+giving rise to an emergent metric tensor. The components of the semi-classical
+metric tensor are calculated from the equation of propagation of the quantum
+K-G field in the test field approximation. The anisotropies are of a quantum
+nature: they are proportional to Planck constant and ""dress"" the isotropic
+classical space-time obtained in the classical limit.",1211.0161v2
+2012-11-06,"Spin dynamics of hard-soft magnetic multi-layer systems: Effect of Exchange, Dipolar and Dzyaloshinski-Moriya interactions","We investigate the effect of coupling (intensity and nature), applied field,
+and anisotropy on the spin dynamics of a multi-layer system composed of a hard
+magnetic slab coupled to a soft magnetic slab through a nonmagnetic spacer. The
+soft slab is modeled as a stack of several atomic layers while the hard layer,
+of a different material, is either considered as a pinned macroscopic magnetic
+moment or as an atomic multi-layer system. We compute the magnetization profile
+and hysteresis loop of the multi-layer system by solving the Landau-Lifshitz
+equations for the net magnetic moment of each (atomic) layer. We study the
+competition between the intra-layer anisotropy and exchange interaction,
+applied magnetic field, and the inter-slab exchange, dipolar or
+Dzyaloshinski-Moriya interaction. Comparing the effects on the magnetization
+profile of the three couplings shows that despite the strong effect of the
+exchange coupling, the dipolar and Dzyaloshinski-Moriya interactions induce a
+slight (but non negligible) deviation in either the polar or azimuthal
+direction thus providing more degrees of freedom for adjusting the spin
+configuration in the multi-layer system.",1211.1217v1
+2012-11-09,Thermal photon production in a strongly coupled anisotropic plasma,"Photons produced in heavy ion collisions escape virtually unperturbed from
+the surrounding medium, thus representing an excellent probe of the conditions
+at the emission point. Using the gauge/gravity duality, we calculate the rate
+of photon production in an anisotropic, strongly coupled N=4 plasma with Nf<<Nc
+quark flavors. We consider arbitrary orientations of the photon momentum with
+respect to the anisotropic direction, as well as arbitrary values of the
+anisotropy. We present results for the correlation functions of two
+electromagnetic currents and for the electric conductivity. These quantities
+can be larger or smaller than the isotropic ones, depending on the direction of
+propagation and polarization of the photons. The total production rate is
+however always larger than the isotropic one, independently of the frequency,
+direction of propagation, and value of the anisotropy.",1211.2199v2
+2012-11-13,Lattice studies of magnetic phenomena in heavy-ion collisions,"We review some experimental consequences of the presence of superstrong
+magnetic fields of order of the nuclear scale in noncentral heavy-ion
+collisions. We present lattice estimates for the strength of the Chiral
+Magnetic Effect (CME) for different quark flavours and argue that the
+dependence of the anisotropy of the distribution of emitted hadrons on their
+flavor content might be used as another experimental evidence of the CME.
+Another possible effect of superstrong magnetic field might be the observed
+abnormal enhancement of dilepton yield. We show that the presence of the
+magnetic field leads to a specific anisotropy of the dilepton emission rate.",1211.3014v1
+2012-11-13,Exploring the origin of the fine structures in the CMB temperature angular power spectrum,"The angular power spectrum of the cosmic microwave background (CMB)
+temperature anisotropies is a good probe to look into the primordial density
+fluctuations at large scales in the universe. Here we re-examine the angular
+power spectrum of the Wilkinson Microwave Anisotropy Probe data, paying
+particular attention to the fine structures (oscillations) at $\ell=100 \sim
+150$ reported by several authors. Using Monte-Carlo simulations, we confirm
+that the gap from the simple power law spectrum is a rare event, about
+2.5--3$\sigma$, if these fine structures are generated by experimental noise
+and the cosmic variance. Next, in order to investigate the origin of the
+structures, we examine frequency and direction dependencies of the fine
+structures by dividing the observed QUV frequency maps into four sky regions.
+We find that the structures around $\ell \sim 120$ do not have significant
+dependences either on frequencies or directions. For the structure around $\ell
+\sim 140$, however, we find that the characteristic signature found in the all
+sky power spectrum is attributed to the anomaly only in the South East region.",1211.3097v1
+2012-11-14,CSL Wave Function Collapse Model as a Mechanism for the Emergence of Cosmological Asymmetries in Inflation,"As previously discussed in (D. Sudarsky, Int.J.Mod.Phys.D20:509-552, (2011);
+[arXiv:0906.0315]), the inflationary account for the emergence of the seeds of
+cosmic structure falls short of actually explaining the generation of
+primordial anisotropies and inhomogeneities. This description starts from a
+symmetric background, and invokes symmetric dynamics, so it cannot explain
+asymmetries. To generate asymmetries, we present an application of the
+Continuous Spontaneous Localization (CSL) model of wave function collapse (P.
+Pearle, Phys. Rev. A 39, 2277, (1989); G. C. Ghirardi, P. Pearle and A. Rimini,
+Phys. Rev. A42, 78 (1990)) in the context of inflation. This modification of
+quantum dynamics introduces a stochastic non-unitary component to the evolution
+of the inflaton field perturbations. This leads to passage from a homogeneous
+and isotropic stage to another, where the quantum uncertainties in the initial
+state of inflation transmute into the primordial inhomogeneities and
+anisotropies. We examine requirements for, and show how to achieve,
+compatibility with the precise observations of the cosmic microwave background
+(CMB) radiation.",1211.3463v3
+2012-11-28,Exploiting breakdown of the similarity relation for diffuse light transport: simultaneous retrieval of scattering anisotropy and diffusion constant,"As manifested in the similarity relation of diffuse light transport, it is
+difficult to assess single scattering characteristics from multiply scattered
+light. We take advantage of the limited validity of the diffusion approximation
+of light transport and demonstrate, experimentally and numerically, that even
+deep into the multiple scattering regime, time-resolved detection of
+transmitted light allows simultaneous assessment of both single scattering
+anisotropy and scattering mean free path, and therefore also macroscopic
+parameters like the diffusion constant and the transport mean free path. This
+is achieved via careful assessment of early light and matching against Monte
+Carlo simulations of radiative transfer.",1211.6690v1
+2012-11-29,A solution to the radiation pressure problem in the formation of massive stars,"We review our recent studies demonstrating that the radiation pressure
+problem in the formation of massive stars can be circumvented via an anisotropy
+of the thermal radiation field. Such an anisotropy naturally establishes with
+the formation of a circumstellar disk. The required angular momentum transport
+within the disk can be provided by developing gravitational torques. Radiative
+Rayleigh-Taylor instabilities in the cavity regions - as previously suggested
+in the literature - are not required and are shown to be not occurring in the
+context of massive star formation.",1211.7064v1
+2012-12-02,Manipulating the magnetic anisotropy of cobalt doped titanium dioxide by carrier accumulation,"Based on first-principles calculations, we predict that the magnetic
+anisotropy energy (MAE) of Co-doped TiO$_2$ sensitively depends on carrier
+accumulation. This magnetoelectric phenomenon provides a promising route to
+directly manipulate the magnetization direction of diluted magnetic
+semiconductor by external electric-fields. We calculate the band structures and
+reveal the origin of carrier-dependent MAE in k-space. In fact, the carrier
+accumulation shifts the Fermi energy and regulates the competing contributions
+to MAE. The first-principles calculations provide a straightforward way to
+design spintronics materials with electrically controllable spin direction.",1212.0175v3
+2012-12-07,CMB interferometry,"Interferometry has been a very successful tool for measuring anisotropies in
+the cosmic microwave background. Interferometers provided the first constraints
+on CMB anisotropies on small angular scales (l~10000) in the 1980s and then in
+the late 1990s and early 2000s made ground-breaking measurements of the CMB
+power spectrum at intermediate and small angular scales covering the l-range
+~100-4000. In 2002 the DASI made the first detection of CMB polarization which
+remains a major goal for current and future CMB experiments. Interferometers
+have also made major contributions to the detection and surveying of the
+Sunyaev-Zel'dovich (SZ) effect in galaxy clusters. In this short review I cover
+the key aspects that made interferometry well-suited to CMB measurements and
+summarise some of the central observations that have been made. I look to the
+future and in particular to HI intensity mapping at high redshifts that could
+make use of the advantages of interferometry.",1212.1729v1
+2012-12-10,Interband Quasiparticle Scattering in Superconducting LiFeAs Reconciles Photoemission and Tunneling Measurements,"Several angle resolved photoemission spectroscopy (ARPES) studies reveal a
+poorly nested Fermi surface of LiFeAs, far away from a spin density wave
+instability, and clear-cut superconducting gap anisotropies. On the other hand
+a very different, more nested Fermi surface and dissimilar gap anisotropies
+have been obtained from quasiparticle interference (QPI) data, which were
+interpreted as arising from intraband scattering within hole-like bands. Here
+we show that this ARPES-QPI paradox is completely resolved by interband
+scattering between the hole-like bands. The resolution follows from an
+excellent agreement between experimental quasiparticle scattering data and
+T-matrix QPI calculations (based on experimental band structure data), which
+allows disentangling interband and intraband scattering processes.",1212.2009v2
+2012-12-13,Material Targets for Scaling All Spin Logic,"All-spin logic devices are promising candidates to augment and complement
+beyond-CMOS integrated circuit computing due to non-volatility, ultra-low
+operating voltages, higher logical efficiency, and high density integration.
+However, the path to reach lower energy-delay product performance compared to
+CMOS transistors currently is not clear. We show that scaling and engineering
+the nanoscale magnetic materials and interfaces is the key to realizing spin
+logic devices that can surpass energy-delay performance of CMOS transistors.
+With validated stochastic nano-magnetic and vector spin transport numerical
+models, we derive the target material and interface properties for the
+nanomagnets and channels. We identified promising new directions for material
+engineering/discovery focusing on systematic scaling of magnetic anisotropy
+(Hk) with saturation magnetization (Ms), use of perpendicular magnetic
+anisotropy, and interface spin mixing conductance of ferromagnet/spin channel
+interface (Gmix). We provide systematic targets for scaling spin logic
+energy-delay product toward a 2 aJ.ns energy-delay product, comprehending the
+stochastic noise for nanomagnets.",1212.3362v1
+2012-12-14,Doping effect on thermoelectric properties of MoS$_2$,"We systematically study thermoelectric properties of layered MoS$_2$ by
+doping, based on Boltzmann transport theory and first-principles calculations.
+We obtain optimal doping region (around 10$^{19}$ cm$^{-3}$) by looking closely
+to the temperature and doping level dependent thermopower, electrical
+conductivity, power factor (PF) and ultimately figure of merit (ZT) coefficient
+along in-plane and cross-plane directions. MoS$_2$ has a vanishingly small
+anisotropy of thermopower but a big anisotropy of electrical conductivity and
+electronic thermal conductivity in optimal doping region. $\kappa_e$ is
+comparable to $\kappa_l$ in the plane while $\kappa_l$ dominates over
+$\kappa_e$ across the plane. ZT can reach as high as 0.3 at around 700 K.
+In-plane direction is demonstrated to be more preferable for thermoelectric
+applications of MoS$_2$ by doping.",1212.3394v2
+2012-12-17,Topological states in pyrochlore iridates: long-range anisotropy strongly competing with spin-orbit interaction,"In the search for topological phases in correlated electron systems,
+iridium-based pyrochlores A2Ir2O7 -- materials with 5d transition-metal ions --
+provide fertile grounds. Several novel topological states have been predicted
+but the actual realization of such states is believed to critically depend on
+the strength of local potentials arising from distortions of IrO6-cages. We
+test this hypothesis by measuring with resonant x-ray scattering the electronic
+level splittings in the A= Y, Eu systems, which we show to agree very well with
+ab initio electronic structure calculations. We find, however, that not
+distortions of IrO6-octahedra are the primary source for quenching the
+spin-orbit interaction, but strong long-range lattice anisotropies, which
+inevitably break the local cubic symmetry and will thereby be decisive in
+determining the system's topological ground state.",1212.4009v2
+2012-12-16,Dynamical 3-Space Gravitational Waves: Reverberation Effect,"Gravity theory missed a key dynamical process that became apparent only when
+expressed in terms of a velocity field, instead of the Newtonian gravitational
+acceleration field. This dynamical process involves an additional
+self-interaction of the dynamical 3-space, and experimental data reveals that
+its strength is set by the fine structure constant, implying a fundamental link
+between gravity and quantum theory. The dynamical 3-space has been directly
+detected in numerous light-speed anisotropy experiments. Quantum matter has
+been shown to exhibit an acceleration caused by the time-dependence and
+inhomogeneity of the 3-space flow, giving the first derivation of gravity from
+a deeper theory, as a quantum wave refraction effect. EM radiation is also
+refracted in a similar manner. The anisotropy experiments have all shown
+3-space wave/turbulence effects, with the latest revealing the fractal
+structure of 3-space. Here we report the prediction of a new effect, namely a
+reverberation effect, when the gravitational waves propagate in the 3-space
+inflow of a large mass. This effect arises from the non-linear dynamics of
+3-space. These reverberations could offer an explanation for the Shnoll effect,
+in which cosmological factors influence stochastic processes, such as
+radioactive decay rates.",1212.4405v1
+2012-12-19,Optical conductivity and Raman scattering of iron superconductors,"We discuss how to analyze the optical conductivity and Raman spectra of
+multi-orbital systems using the velocity and the Raman vertices in a similar
+way Raman vertices were used to disentangle nodal and antinodal regions in
+cuprates. We apply this method to iron superconductors in the magnetic and
+non-magnetic states, studied at the mean field level. We find that the
+anisotropy in the optical conductivity at low frequencies reflects the
+difference between the magnetic gaps at the X and Y electron pockets. Both gaps
+are sampled by Raman spectroscopy. We also show that the Drude weight
+anisotropy in the magnetic state is sensitive to small changes in the lattice
+structure.",1212.4765v2
+2012-12-31,Towards efficient and optimal analysis of CMB anisotropies on a masked sky,"Strong foreground contamination in high resolution CMB data requires masking
+which introduces statistical anisotropies and renders a full maximum likelihood
+analysis numerically intractable. Standard analysis methods like the pseudo-C_l
+framework lead to information loss due to estimator suboptimalities. We set out
+and validate a methodology for numerically efficient estimators for a masked
+sky that recover nearly as much information as a full maximum likelihood
+procedure. In addition to the standard pseudo-C_l statistic, the approach
+introduces an augmented basis designed to account for the mode coupling due to
+the masking of the sky. We motivate the choice of this basis by describing the
+basic structure of the covariance matrix. We demonstrate that the augmented
+estimator can achieve near-optimal results in the presence of a WMAP-realistic
+mask.",1212.6945v2
+2013-01-08,Interplay between interaction and chiral anomaly: Anisotropy in the electrical resistivity of interacting Weyl metals,"We predict that long-range interactions give rise to anisotropy in the
+electrical resistivity of Weyl metals at low temperatures, where the electrical
+resistivity becomes much reduced when electric fields are applied to the
+direction of the momentum vector to connect two paired Weyl points. Performing
+the renormalization group analysis, we find that the distance between two Weyl
+points becomes enhanced logarithmically at low temperatures although the
+coupling constant of such interactions vanishes inverse-logarithmically.
+Considering the Adler-Bell-Jackiw anomaly, scattering between these two Weyl
+points becomes suppressed to increase electrical conductivity in the
+""longitudinal"" direction, counter-intuitive in the respect that interactions
+are expected to reduce metallicity. We also propose that the anomalous
+contribution in the Hall effect shows the logarithmic enhancement as a function
+of temperature, originating from the fact that the anomalous Hall coefficient
+turns out to be proportional to the distance between two paired Weyl points.
+Correlations with topological constraints allow unexpected and exotic transport
+properties.",1301.1436v2
+2013-01-08,Phase diagram of the Anderson transition with atomic matter waves,"We realize experimentally a cold atom system equivalent to the 3D Anderson
+model of disordered solids where the anisotropy can be controlled by adjusting
+an experimentally accessible parameter. This allows us to study experimentally
+the disorder vs anisotropy phase diagram of the Anderson metal-insulator
+transition. Numerical and experimental data compare very well with each other
+and a theoretical analysis based on the self-consistent theory of localization
+correctly discribes the observed behavior, illustrating the flexibility of cold
+atom experiments for the study of transport phenomena in complex quantum
+systems.",1301.1615v1
+2013-01-10,Magnetic structure and magnon dispersion in LaSrFeO$_4$,"We present elastic and inelastic neutron scattering data on LaSrFeO$_4$. We
+confirm the known magnetic structure with the magnetic moments lying in the
+tetragonal basal plane, but contrarily to previous reports our macroscopic and
+neutron diffraction data do not reveal any additional magnetic phase transition
+connected to a spin reorientation or to a redistribution of two irreducible
+presentations. Our inelastic neutron scattering data reveals the magnon
+dispersion along the main-symmetry directions [0 $\xi$ 0] and [$\xi$ -$\xi$ 0].
+The dispersion can be explained within linear spin-wave theory yielding an
+antiferromagnetic nearest-neighbour interaction parameter $J_{1}=7.4(1)$ meV
+and a next-nearest neighbour interaction parameter $J_{2}=0.4(1)$ meV. The
+dispersion is gapped with the out-of-plane anisotropy gap found at
+$\Delta_{out}=5.26(2)$ meV, while evidence is present that the in-plane
+anisotropy gap lies at lower energies, where it cannot be determined due to
+limited instrument resolution.",1301.2106v1
+2013-01-14,Impact of anisotropy on the noncritical squeezing properties of two-transverse-mode optical parametric oscillators,"In a series of articles we studied the quantum properties of a degenerate
+optical parametric oscillator tuned to the first family of transverse modes at
+the subharmonic. We found that, for a cavity having rotational symmetry respect
+to the optical axis, a TEM$_{10}$ mode with an arbitrary orientation in the
+transverse plane is emitted above threshold. We proved then that quantum noise
+induces a random rotation of this bright TEM$_{10}$ mode in the transverse
+plane, while the mode orthogonal to it, the so-called dark mode, has perfect
+quadrature squeezing irrespective of the distance to threshold (noncritical
+squeezing). This result was linked to the spontaneous rotational symmetry
+breaking which occurs when the bright mode is generated, and here we analyze
+how the squeezing of the dark mode is degraded when the cavity is not perfectly
+symmetric. We will show that large levels of squeezing are still attainable for
+reasonable values of this anisotropy, with the advantage that the orientation
+of the bright and dark modes is basically fixed, a very attractive situation
+from the experimental point of view.",1301.2849v1
+2013-01-17,Anisotropic Zeeman splitting in p-type GaAs quantum point contacts,"Low-temperature electrical conductance spectroscopy measurements of quantum
+point contacts implemented in p-type GaAs/AlGaAs heterostructures are used to
+study the Zeeman splitting of 1D subbands for both in-plane and out-of-plane
+magnetic field orientations. The resulting in-plane g-factors agree
+qualitatively with those of previous experiments on quantum wires while the
+quantitative differences can be understood in terms of the enhanced quasi-1D
+confinement anisotropy. The influence of confinement potential on the
+anisotropy is discussed and an estimate for the out-of-plane g-factor is
+obtained which, in contrast to previous experiments, is closer to the
+theoretical prediction.",1301.3992v1
+2013-01-21,Quantum master equation for a system of identical particles,"We consider an open quantum many-particle system in which there are
+dissipative processes. The evolution of this system is described by a kinetic
+equation for the density matrix. From the equation describing a random Markov
+process in this system, we obtain an equation for the single-particle
+statistical operator. This equation describes the evolution of a system of
+identical particles in a mean-field approximation. The equation for interacting
+particles in thermodynamic equilibrium was obtained. The distribution function
+of a system of interacting electrons in metals has multivalence in a certain
+region of wave vectors. Among many solutions one is isotropic. Other solutions
+have the anisotropy of the electron distribution over the wave vectors. The
+anisotropy arises as a result of repulsion and attraction between electrons.",1301.4712v1
+2013-01-23,Neutrino emissivity of anisotropic neutron superfluids,"We examine the influence of the anisotropy of the superfluid energy gap and
+residual Fermi-liquid interactions in the triplet-correlated neutron liquid
+onto neutrino energy losses through neutral weak currents. The neutrino-pair
+emission caused by the pair breaking and formation processes and by the
+spin-wave decays is considered for the case of the $^{3}P_{2}$ pairing in the
+state with $m_{j}=0$. The simple analytical formulae are obtained. A comparison
+with the previous results of the average-angle approach shows that the gap
+anisotropy leads to quenching of the neutrino emissivity caused by the pair
+recombination processes on about 15% and to substantial suppression of the
+spin-wave decays. Residual particle-hole interactions increase the energy
+losses in both the channels on about 5%.",1301.5439v1
+2013-01-24,Optimal conditions for magnetization reversal of nanocluster assemblies with random properties,"Magnetization dynamics in the system of magnetic nanoclusters with randomly
+distributed properties are studied by means of computer simulations. The main
+attention is paid to the possibility of coherent magnetization reversal from a
+strongly nonequilibrium state with a mean cluster magnetization directed
+opposite to an external magnetic field. Magnetic nanoclusters are known to be
+characterized by large magnetic anisotropy and strong dipole interactions. It
+is also impossible to produce a number of nanoclusters with identical
+properties. As a result, any realistic system of nanoclusters is composed of
+the clusters with randomly varying anisotropies, effective spins, and dipole
+interactions. Despite this randomness, it is possible to find conditions when
+the cluster spins move coherently and display fast magnetization reversal due
+to the feedback action of resonator. By analyzing the influence of different
+cluster parameters, we find their optimal values providing fast magnetization
+reversal.",1301.5789v1
+2013-01-31,Anisotropic hydrodynamics -- basic concepts,"Due to the rapid longitudinal expansion of the quark-gluon plasma created in
+relativistic heavy ion collisions, potentially large local rest frame
+momentum-space anisotropies are generated. The magnitude of these
+momentum-space anisotropies can be so large as to violate the central
+assumption of canonical viscous hydrodynamical treatments which linearize
+around an isotropic background. In order to better describe the early-time
+dynamics of the quark gluon plasma, one can consider instead expanding around a
+locally anisotropic background which results in a dynamical framework called
+anisotropic hydrodynamics. In this proceedings contribution we review the basic
+concepts of the anisotropic hydrodynamics framework presenting viewpoints from
+both the phenomenological and microscopic points of view.",1301.7539v1
+2013-01-31,Further details on the phase diagram of hard ellipsoids of revolution,"In recent work we revisited the phase diagram of hard ellipsoids of
+revolution (spheroids) by means of replica exchange Monte Carlo simulations.
+This was done by setting random initial configurations, and allows to confirm
+the formation of sm2 crystal structures at high densities [Phys. Rev. E 75,
+020402 (2007)] for large anisotropies and stretched-fcc for small anisotropies.
+In this work we employed the same technique but setting the starting cells as
+sm2 crystal structures having the maximum known packing density [Phys. Rev.
+Lett. 92, 255506 (2004)]. This procedure yields a very rich behavior for
+quasi-spherical oblates and prolates. These systems, from low to high
+pressures, show the following phases: isotropic fluid, plastic solid,
+stretched-fcc solid, and sm2 solid. The first three transitions are first
+order, whereas the last one is a subtle, probably high order transition. This
+picture is consistent with the fact of having the sm2 structure capable of
+producing the maximally achievable density.",1301.7728v1
+2013-02-01,"Spin relaxation and the Elliott-Yafet parameter in W(001) ultrathin films: surface states, anisotropy and oscillation effects","Using first-principles methods based on density-functional theory we
+investigate the spin relaxation in W(001) ultrathin films. Within the framework
+of the Elliott-Yafet theory we calculate the spin mixing of the Bloch states
+and we explicitly consider spin-flip scattering off self-adatoms. We find an
+oscillatory behavior of the spin-mixing parameter and relaxation rate as a
+function of the film thickness, which we trace back tosurface-state properties.
+We also analyze the Rashba effect experienced by the surface states and discuss
+its influence on the spin relaxation. Finally we calculate the anisotropy of
+the spin-relaxation rate with respect to the polarization direction of the
+excited spin population relative to the crystallographic axes of thefilm. We
+find that the spin-relaxation rate can increase by as much as 47% when the spin
+polarization is directed out of plane, compared to the case when it is in
+plane. Our calculations are based on the multiple-scattering formalism of the
+Korringa-Kohn-Rostoker Green-function method.",1302.0140v1
+2013-02-09,The effect of uniaxial pressure on the magnetic anisotropy of the Mn_{12}-Ac single-molecule magnet,"We study the effect of uniaxial pressure on the magnetic hysteresis loops of
+the single-molecule magnet Mn_{12}-Ac. We find that the application of pressure
+along the easy axis increases the fields at which quantum tunneling of
+magnetization occurs. The observations are attributed to an increase in the
+molecule's magnetic anisotropy constant D of 0.142(1)%/kbar. The increase in D
+produces a small, but measurable increase in the effective energy barrier for
+magnetization reversal. Density-functional theory calculations also predict an
+increase in the barrier with applied pressure.",1302.2276v2
+2013-02-17,Ab initio study of low-energy electronic collective excitations in bulk Pb: anisotropy and acoustic modes,"A theoretical study of the dynamical dielectric response of bulk lead at low
+energies is presented. The calculations are performed with full inclusion of
+the electron band structure calculated by means of a first-principles
+pseudopotential approach. The effect of including the spin-orbit splittings in
+the band structure is analyzed, together with dynamical exchange-correlation
+and local-field effects. Excitations are studied in detail, showing the
+presence at small momenta of acoustic-like dispersing excitations. The
+character of these modes with sound-like dispersion depends on the direction of
+the momentum transfer q. In general results show strong anisotropy effects on
+the dielectric response of bulk Pb. Comparison with available optical
+experimental data shows good agreement.",1302.4104v2
+2013-02-19,Spin-flip hot spots in ultrathin films of monovalent metals: Enhancement and anisotropy of the Elliott-Yafet parameter,"In contrast to the long-known fact that spin-flip hot spots, i.e., special
+\vc{k}-points on the Fermi surface showing a high spin-mixing parameter, do not
+occur in the bulk of monovalent (noble and alkali) metals, we found them on the
+surface Brillouin-zone boundary of ultrathin films of these metals.
+Density-functional calculations within the Korringa-Kohn-Rostoker Green
+function method for ultrathin (001) oriented Cu, Ag, and Au films of 10-layer
+thickness show that the region around the hot spots can have a substantial
+contribution, e.g.\ 52\% in Au(001), to the integrated spin-mixing parameter,
+that could lead to a significant enhancement of the spin-relaxation rate or
+spin-Hall angle in thin films. Owing to the appearance of spin-flip hot-spots,
+a large anisotropy of the Elliott-Yafet parameter [50\% for Au(001)] is also
+found in these systems. The findings are important for spintronics applications
+in which noble-metals are frequently used and in which the dimensionality of
+the sample is reduced.",1302.4671v2
+2013-02-25,Anisotropic universes in the ghost-free bigravity,"We study Bianchi cosmologies in the ghost-free bigravity theory assuming both
+metrics to be homogeneous and anisotropic, of the Bianchi class A, which
+includes types I,II,VI$_0$,VII$_0$,VIII, and IX. We assume the universe to
+contain a radiation and a non-relativistic matter, with the cosmological term
+mimicked by the graviton mass. We find that, for generic initial values leading
+to a late-time self-acceleration, the universe approaches a state with
+non-vanishing anisotropies. The anisotropy contribution to the total energy
+density decreases much slower than in General Relativity and shows the same
+falloff rate as the energy of a non-relativistic matter. The solutions show a
+singularity in the past, and in the Bianchi IX case the singularity is
+approached via a sequence of Kasner-like steps, which is characteristic for a
+chaotic behavior.",1302.6198v3
+2013-02-26,Motion induced second order temperature and y-type anisotropies after the subtraction of linear dipole in the CMB maps,"y-type spectral distortions of the cosmic microwave background allow us to
+detect clusters and groups of galaxies, filaments of hot gas and the
+non-uniformities in the warm hot intergalactic medium. Several CMB experiments
+(on small areas of sky) and theoretical groups (for full sky) have recently
+published y-type distortion maps. We propose to search for two artificial hot
+spots in such y-type maps resulting from the incomplete subtraction of the
+effect of the motion induced dipole on the cosmic microwave background sky.
+This dipole introduces, at second order, additional temperature and
+y-distortion anisotropy on the sky of amplitude few \mu K which could
+potentially be measured by Planck HFI and Pixie experiments and can be used as
+a source of cross channel calibration by CMB experiments. This y-type
+distortion is present in every pixel and is not the result of averaging the
+whole sky. This distortion, calculated exactly from the known linear dipole,
+can be subtracted from the final y-type maps, if desired.",1302.6571v1
+2013-03-05,Strangelets and the TeV-PeV cosmic-ray anisotropies,"Several experiments (e.g., Milagro and IceCube) have reported the presence in
+the sky of regions with significant excess in the arrival direction
+distributions of Galactic cosmic rays in the TeV to PeV energy range. Here we
+study the possibility that these hotspots are a manifestation of the peculiar
+nature of these cosmic rays, and of the presence of molecular clouds near the
+sources. We propose that stable quark matter lumps or so-called ""strangelets""
+can be emitted in the course of the transition of a neutron star to a more
+compact astrophysical object. A fraction of these massive particles would lose
+their charge by spallation or electron capture in molecular clouds located in
+the immediate neighborhood of their source, and propagate rectilinearly without
+decaying further, hence inducing anisotropies of the order of the cloud size.
+With reasonable astrophysical assumptions regarding the neutron star transition
+rate, strangelet injection and neutralization rates, we can reproduce
+successfully the observed hotspot characteristics and their distribution in the
+sky.",1303.1186v1
+2013-03-05,"Angle-Dependent Spin-Wave Resonance Spectroscopy of (Ga,Mn)As Films","A modeling approach for standing spin-wave resonances based on a
+finite-difference formulation of the Landau-Lifshitz-Gilbert equation is
+presented. In contrast to a previous study [Bihler et al., Phys. Rev. B 79,
+045205 (2009)], this formalism accounts for elliptical magnetization precession
+and magnetic properties arbitrarily varying across the layer thickness,
+including the magnetic anisotropy parameters, the exchange stiffness, the
+Gilbert damping, and the saturation magnetization. To demonstrate the
+usefulness of our modeling approach, we experimentally study a set of (Ga,Mn)As
+samples grown by low-temperature molecular-beam epitaxy by means of
+electrochemical capacitance-voltage measurements and angle-dependent standing
+spin-wave resonance spectroscopy. By applying our modeling approach, the angle
+dependence of the spin-wave resonance data can be reproduced in a simulation
+with one set of simulation parameters for all external field orientations. We
+find that the approximately linear gradient in the out-of-plane magnetic
+anisotropy is related to a linear gradient in the hole concentrations of the
+samples.",1303.1192v1
+2013-03-08,Interplay of inter-chain interactions and exchange anisotropy: Stability of multipolar states in quasi-1D quantum helimagnets,"We quantify the instability towards the formation of multipolar states in
+coupled spin-1/2 chain systems with a frustrating J1-J2 exchange, in parameter
+regimes that are of directly relevance to edge-shared cuprate spin-chain
+compounds. Three representative types of inter-chain coupling and the presence
+of uniaxial exchange anisotropy are considered. The magnetic phase diagrams are
+determined by Density Matrix Renormalization Group calculations and completed
+by exact analytic results for the nematic and dipolar phases. We establish that
+the residual couplings strongly affect the pitch of spiral states and their
+instability to multipolar phases. Our theoretical results bring to the fore
+novel candidate materials close to quantum nematic/triatic ordering.",1303.1933v1
+2013-03-10,Towards Anisotropy-Free and Non-Singular Bounce Cosmology with Scale-invariant Perturbations,"We investigate non-singular bounce realizations in the framework of
+ghost-free generalized Galileon cosmology, which furthermore can be free of the
+anisotropy problem. Considering an Ekpyrotic-like potential we can obtain a
+total Equation-of-State (EoS) larger than one in the contracting phase, which
+is necessary for the evolution to be stable against small anisotropic
+fluctuations. Since such a large EoS forbids the Galileon field to generate the
+desired form of perturbations, we additionally introduce the curvaton field
+which can in general produce the observed nearly scale-invariant spectrum. In
+particular, we provide approximate analytical and exact semi-analytical
+expressions under which the bouncing scenario is consistent with observations.
+Finally, the combined Galileon-curvaton system is free of the Big-Rip after the
+bounce.",1303.2372v2
+2013-03-12,Cosmic ray anisotropies to 5 PeV,"Several large cosmic ray (CR) detectors have recently provided data on the
+arrival directions of CR, which taken together with previous data recorded over
+many decades allow the amplitgude and phase of the first harmonic to be derived
+with reasonable precision and up to higher energies. We find a high degree of
+consistency amongst the various measurements. The new data indicate that at an
+energy above ~0.1 PeV a change of the CR anisotropy sets in. The amplitude of
+the first harmonic, which rises to 3 TeV, then diminishes and begins to rise
+again. The direction of the phase also changes to the opposite one. A measure
+of understanding follows from the use of two-dimensional maps of CR excesses
+over the mean background. When the energy of CR approaches the PeV region, the
+excess of CR moves from the Galactic Anti-Centre to the opposite direction of
+the Galactic Centre. The possible role of such potential CR sources as the
+supernovae Monogem Ring and Vela, which could help to explain some of the
+observed results, is discussed.",1303.2889v1
+2013-03-13,Crystalline symmetry and the melt-growth kinetics of solid-liquid interface,"One of the important factors governing the growth morphology of materials is
+the interface kinetic coefficient \mu, which is the proportionality constant
+between the velocity of solid-liquid interface and undercooling. We employ
+Ginzburg-Landau (GL) free energy functional to derive an analytical expression
+of kinetic coefficients. The anisotropy of kinetic coefficients naturally arise
+from the broken symmetry at the solid-liquid interface for various crystalline
+orientations. The analytical expression of kinetic coefficients is compared to
+Mikheev-Chernov theory [J. Cryst. Growth 112, 591 (1991)] derived from
+hydrodynamic equations. In addition, we use equilibrium density wave profiles
+to evaluate kinetic coefficients and compare them with that from MD
+simulations. Our results are in good agreement with Mikheev-Chernov theory and
+MD simulations and shed lights on a possible origin of anisotropy of
+interfacial kinetics.",1303.3111v2
+2013-03-18,Frictional anisotropy of metal nanoparticles adsorbed on graphene,"Friction force acting on silver and nickel nanoparticles sheared on a
+graphene sheet in different lateral directions is investigated using classical
+molecular dynamics simulations. The results reveal the existence of frictional
+anisotropy for both metals. In most cases, the maximum value of the friction
+force is about two times larger than the minimum one. The form of dependencies
+of instantaneous values of the friction force components on the corresponding
+lateral components of the position of the centre of mass of the nanoislands
+strongly depends on sliding direction, varying between the sawtooth and the
+irregular one. A qualitative explanation of the results based on the ""patch""
+model is proposed.",1303.4187v1
+2013-03-19,Maximum Entropy deconvolution of Primordial Power Spectrum,"It is well known that CMB temperature anisotropies and polarization can be
+used to probe the metric perturbations in the early universe. Presently, there
+exist neither any observational detection of tensor modes of primordial metric
+perturbations nor of primordial non-Gaussianity. In such a scenario, primordial
+power spectrum of scalar metric perturbations is the only correlation function
+of metric perturbations (presumably generated during inflation) whose effects
+can be directly probed through various observations. To explore the possibility
+of any deviations from the simplest picture of the era of cosmic inflation in
+the early universe, it thus becomes extremely important to uncover the
+amplitude and shape of this (only available) correlation sufficiently well. In
+the present work, we attempt to reconstruct the primordial power spectrum of
+scalar metric perturbations using the binned (uncorrelated) CMB temperature
+anisotropies data using the Maximum Entropy Method (MEM) to solve the
+corresponding inverse problem. Our analysis shows that, given the current CMB
+data, there are no convincing reasons to believe that the primordial power
+spectrum of scalar metric perturbations has any significant features.",1303.4747v1
+2013-03-26,Study of the electronic nematic phase of Sr$_3$Ru$_2$O$_7$ with precise control of the applied magnetic field vector,"We report a study of the magnetoresistivity of high purity Sr$_3$Ru$_2$O$_7$,
+in the vicinity of its electronic nematic phase. By employing a triple-axis
+(9/1/1T) vector magnet, we were able to precisely tune both the magnitude and
+direction of the in-plane component of the magnetic field (H$_\parallel$). We
+report the dependence of the resistively determined anisotropy on H$_\parallel$
+in the phase, as well as across the wider temperature-field region. Our
+measurements reveal a high-temperature anisotropy which mimics the behaviour of
+fluctuations from the underlying quantum critical point, and suggest the
+existence of a more complicated phase diagram than previously reported.",1303.6459v1
+2013-04-03,Adhesion and size dependent friction anisotropy in boron nitride nanotubes,"The frictional properties of individual multiwalled boron nitride nanotubes
+(BN-NTs) synthesized by chemical vapor deposition (CVD) and deposited on a
+silicon substrate are investigated using an atomic force microscope tip sliding
+along (longitudinal sliding) and across (transverse sliding) the tube's
+principal axis. Because of the tube transverse deformations during the tip
+sliding, a larger friction coefficient is found for the transverse sliding as
+compared to the longitudinal sliding. Here, we show that the friction
+anisotropy in BN-NTs, defined as the ratio between transverse and longitudinal
+friction forces per unit area, increases with the nanotube-substrate contact
+area. Larger contact area denotes stronger surface adhesion, resulting in a
+longitudinal friction coefficient closer to the value expected in absence of
+transverse deformations. Compared to carbon nanotubes (C-NT), BN-NTs display a
+friction coefficient in each sliding direction with intermediate values between
+CVD and arc discharge C-NTs. CVD BN-NTs with improved tribological properties
+and higher oxidation temperature might be a better candidate than CVD C-NTs for
+applications in extreme environments.",1304.1013v1
+2013-04-03,Magnetic topology and current channels in plasmas with toroidal current density inversions,"The equilibrium magnetic field inside axisymmetric plasmas with inversions on
+the toroidal current density is studied. Structurally stable non-nested
+magnetic surfaces are considered. For any inversion in the internal current
+density the magnetic families define several positive current channels about a
+central negative one. A general expression relating the positive and negative
+currents is derived in terms of a topological anisotropy parameter. Next, an
+analytical local solution for the poloidal magnetic flux is derived and shown
+compatible with current hollow magnetic pitch measurements shown in the
+literature. Finally, the analytical solution exhibits non-nested magnetic
+families with positive anisotropy, indicating that the current inside the
+positive channels have at least twice the magnitude of the central one.",1304.1029v1
+2013-04-03,Loops and spurs: The angular power spectrum of the Galactic synchrotron background,"We present a new model of the diffuse Galactic synchrotron radiation,
+concentrating on its angular anisotropies. While previous studies have focussed
+on either the variation of the emissivity on large (kpc) scales, or on
+fluctuations due to MHD turbulence in the interstellar medium, we unify these
+approaches to match the angular power spectrum. We note that the usual
+turbulence cascade calculation ignores spatial correlations at the injection
+scale due to compression of the interstellar medium by old supernova remnants
+-- the 'radio loops', only four of which are visible by eye in radio maps. This
+new component naturally provides the otherwise missing power on intermediate
+and small scales in the all-sky map at 408 MHz. Our model can enable more
+reliable subtraction of the synchrotron foreground for studies of CMB
+anisotropies (both in temperature and polarisation) or searches for dark matter
+annihilation. We conclude with some remarks on the relevance to modelling of
+the polarised foreground.",1304.1078v2
+2013-04-09,Half-metallicity and anisotropy magnetoresistance properties of Heusler alloys Fe2Co1-xCrxSi,"In this paper, we investigate the half-metallicity of Heusler alloys
+Fe2Co1-xCrxSi by first principles calculations and anisotropy magnetoresistance
+measurements. It is found that, with the increase of Cr content x, the Fermi
+level of Fe2Co1-xCrxSi moves from the top of valence band to the bottom of
+conduction band, and a large half-metallic band gap of 0.75 eV is obtained for
+x=0.75. We then successfully synthesized a series Heusler Fe2Co1-xCrxSi
+polycrystalline ribbon samples. The results of X-ray diffraction indicate that
+the Fe2Co1-xCrxSi series of samples are pure phase with a high degree of order
+and the saturation magnetic moment follows half-metallic Slater-Pauling rule.
+Except for the two end members, Fe2CoSi and Fe2CrSi, the anisotropic
+magnetoresistance of Fe2Co1-xCrxSi (x=0.25, 0.5, 0.75) show a negative value
+suggesting they are stable half-metallic ferromagnets.",1304.2602v1
+2013-04-10,Newtonian polytropes for anisotropic matter: General framework and applications,"We set up the general formalism to model polytropic Newtonian stars with
+anisotropic pressure. We obtain the corresponding Lane-Emden equation. A
+heuristic model based on an ansatz to obtain anisotropic matter solutions from
+known solutions for isotropic matter is adopted to illustrate the effects of
+the pressure anisotropy on the structure of the star. In particular, we
+calculate the Chandrasekhar mass for a white dwarf. It is clearly displayed how
+the Chandrasekhar mass limit changes depending on the anisotropy. Prospective
+astrophysical applications of the proposed approach are discussed.",1304.2824v2
+2013-04-15,Field dependence of the Spin State and Spectroscopic Modes of Multiferroic BiFeO$_3$,"The spectroscopic modes of multiferroic BiFeO$_3$ provide detailed
+information about the very small anisotropy and Dzyaloshinskii-Moriya (DM)
+interactions responsible for the long-wavelength, distorted cycloid below $\TN
+= 640$ K. A microscopic model that includes two DM interactions and easy-axis
+anisotropy predicts both the zero-field spectroscopic modes as well as their
+splitting and evolution in a magnetic field applied along a cubic axis. While
+only six modes are optically active in zero field, all modes at the cycloidal
+wavevector are activated by a magnetic field. The three magnetic domains of the
+cycloid are degenerate in zero field but one domain has lower energy than the
+other two in nonzero field. Measurements imply that the higher-energy domains
+are depopulated above about 6 T and have a maximum critical field of 16 T,
+below the critical field of 19 T for the lowest-energy domain. Despite the
+excellent agreement with the measured spectroscopic frequencies, some
+discrepancies with the measured spectroscopic intensities suggest that other
+weak interactions may be missing from the model.",1304.4195v3
+2013-04-22,Magnetic anisotropic energy gap and low energy spin wave excitation in antiferromagnetic block phase of K2Fe4Se5,"Neutron scattering experiments were performed to investigate magnetic order
+and magnetic excitations in ternary iron chalcogenide K2Fe4Se5. The formation
+of a superlattice structure below 580 K together with the decoupling between
+the Fe-vacancy order-disorder transition and the antiferromagnetic order
+transition appears to be a common feature in the A2Fe4Se5 family. The study of
+spin dynamics of K2Fe4Se5 reveals two distinct energy gaps at the magnetic
+Brillouin zone center, which indicates the presence of magnetic anisotropy and
+the decrease of local symmetry due to electronic and orbital anisotropy. The
+low-energy spin wave excitations of K2Fe4Se5 can be properly described by
+linear spin wave theory within a Heisenberg model. Compared to iron pnictides,
+K2Fe4Se5 exhibits a more two-dimensional magnetism as characterized by large
+differences not only between out-of-plane and in-plane spin wave velocities,
+but also between out-of-plane and in-plane exchange interactions.",1304.5950v1
+2013-04-29,Completely flat bands and fully localized states on surfaces of anisotropic diamond-lattice models,"We discuss flat-band surface states on the (111) surface in the tight-binding
+model with nearest-neighbor hopping on the diamond lattice, in analogy to the
+flat-band edge states in graphene with a zigzag edge. The bulk band is gapless,
+and the gap closes along a loop in the Brillouin zone. The verge of the
+flat-band surface states is identical with this gap-closing loop projected onto
+the surface plane. When anisotropies in the hopping integrals increase, the
+bulk gap-closing points move and the distribution of the flat-band states
+expands in the Brillouin zone. Then when the anisotropy is sufficiently large,
+the surface flat bands cover the whole Brillouin zone. Because of the
+completely flat bands, we can construct surface-state wavefunctions which are
+localized in all the three directions.",1304.7592v3
+2013-05-07,Micromagnetic modelling of anisotropic damping in ferromagnet,"We report a numerical implementation of the Landau-Lifshitz-Baryakhtar
+theory, which dictates that the micromagnetic relaxation term obeys the
+symmetry of the magnetic crystal, i. e. replacing the single intrinsic damping
+constant with a tensor of corresponding symmetry. The effect of anisotropic
+relaxation is studied in thin saturated ferromagnetic disk and ellipse with and
+without uniaxial magneto-crystalline anisotropy. We investigate the angular
+dependency of the linewidth of magnonic resonances with respect to the given
+structure of the relaxation tensor. The simulations suggest that the anisotropy
+of the magnonic linewidth is determined by only two factors: the projection of
+the relaxation tensor onto the plane of precession and the ellipticity of the
+later.",1305.1641v2
+2013-05-15,Azimuthal Anisotropy from STAR Experiment,"We report the measurement of first (\textit{n} = 1) and higher
+order(\textit{n} = 2-5) harmonic coefficients ($v_{n}$) of the azimuthal
+anisotropy in the distribution of the particles produced in Au+Au collisions at
+$\sqrt{s_{NN}}$ =200 GeV and U+U collisions at $\sqrt{s_{NN}}$ =193 GeV,
+recorded with the STAR detector at RHIC. The differential measurement of
+$(v_{n})$ is presented as a function of transverse momentum ($p_{T}$) and
+centrality. We also present $v_{n}$ measurement in the ultra-central collisions
+in U+U collisions. These data may provide strong constraints on the theoretical
+models of the initial condition in heavy ion collisions and the transport
+properties of the produced medium.",1305.3624v2
+2013-05-23,Two-dimensional arrays of superconducting and soft magnetic strips as dc magnetic metamaterials,"We have theoretically investigated the magnetic response of two-dimensional
+(2D) arrays of superconducting and soft magnetic strips, which are regarded as
+models of dc magnetic metamaterials. The anisotropy of the macroscopic
+permeabilities depends on whether the applied magnetic field is parallel to the
+wide surface of the strips ($\mu_{\parallel}$) or perpendicular
+($\mu_{\perp}$). For the 2D arrays of superconducting strips,
+$0<\mu_{\perp}/\mu_0\ll \mu_{\parallel}/\mu_0\simeq 1$, whereas for the 2D
+arrays of soft magnetic strips,
+$\mu_{\parallel}/\mu_0\gg\mu_{\perp}/\mu_0\simeq 1$, where $\mu_0$ is the
+vacuum permeability. We also demonstrate that strong anisotropy of the
+macroscopic permeability can be obtained for hybrid arrays of superconducting
+and soft magnetic strips, where $\mu_{\parallel}/\mu_0\gg 1\gg
+\mu_{\perp}/\mu_0>0$.",1305.5318v1
+2013-05-29,Enhanced interface perpendicular magnetic anisotropy in Ta|CoFeB|MgO using nitrogen doped Ta underlayers,"We show that the magnetic characteristics of Ta|CoFeB|MgO magnetic
+heterostructures are strongly influenced by doping the Ta underlayer with
+nitrogen. In particular, the saturation magnetization drops upon doping the Ta
+underlayer, suggesting that the doped underlayer acts as a boron diffusion
+barrier. In addition, the thickness of the magnetic dead layer decreases with
+increasing nitrogen doping. Surprisingly, the interface magnetic anisotropy
+increases to ~1.8 erg/cm2 when an optimum amount of nitrogen is introduced into
+the Ta underlayer. These results show that nitrogen doped Ta serves as a good
+underlayer for Spintronics applications including magnetic tunnel junctions and
+domain wall devices.",1305.6660v1
+2013-05-30,Evolution of ferromagnetic and spin-wave resonances with crystalline order in thin films of full-Heusler alloy Co2MnSi,"We report the evolution of magnetic moment as well as magnetic anisotropy
+with crystalline order in Co$_2$MnSi thin films grown on $(100)$ MgO by pulsed
+laser deposition. The films become more ordered as the annealing temperature
+($T_A$) increases from 400 to 600 $^0$C. The extent of \emph{L}$2_1$ ordering
+in the films annealed at 600 $^0$C is $\approx 96%$. The static magnetization
+measurements by vibrating sample magnetometry shows a maximum moment of 4.95
+$\mu_B$ per formula unit with low coercivity ($H_C$ $\approx$ 65 Oe) in the
+films annealed at 600 $^0$C. A rigorous analysis of the azimuthal and polar
+angle dependent ferromagnetic resonance (FMR) measured at several temperatures
+allows determination of various anisotropy fields relevant to our system as a
+function of $T_A$. Finally, we have evaluated the exchange stiffness constant
+down to 100 K using spin wave modes in FMR spectra. We have also estimated the
+exchange energies as well as stiffness constant by varying the lattice
+parameter \emph{ab-initio} using the Korringa-Kohn-Rostoker method.",1305.7048v1
+2013-06-07,Strong anisotropy in quasi-static magnetohydrodynamic turbulence for high interaction parameters,"We simulate forced quasi-static magnetohydrodynamic turbulence and
+investigate the anisotropy, energy spectrum, and energy flux of the flow,
+specially for large interaction parameters ($N$). We show that the angular
+dependence of the energy spectrum is well quantified using Legendre
+polynomials. For large $N$, the energy spectrum is exponential. Our direct
+computation of energy flux reveals an inverse cascade of energy at low
+wavenumbers, similar to that in two-dimensional turbulence. We observe the flow
+be two-dimensional (2D) for moderate $N$ ($N \sim 20$), and two-dimensional
+three-component (2D-3C) type for $N \ge 27$. In our forced simulation, the
+transition from 2D to 2D-3C occurs at higher value of $N$ than Favier et al.,
+[""On the two-dimensionalization of quasistatic magnetohydrodynamic turbulence,""
+Phys. Fluids 22, 075104 (2010)] who employ decaying simulations.",1306.1611v2
+2013-06-09,"First-principles calculations of the structural, electronic, optical and elastic properties of the CuYS2 semiconductor","Ternary semiconductor CuYS2 is studied by using the first-principles methods
+in the density functional theory (DFT) framework. The structural, electronic,
+optical and elastic properties were calculated at the ambient and elevated
+hydrostatic pressures. The compound was shown to have an indirect band gap of
+about 1.342/1.389 eV (in the generalized gradient and local density
+approximations). The anisotropy of the optical properties was studied by
+calculating the absorption spectra, dielectric function and index of refraction
+for different polarizations. The anisotropy of the elastic properties was
+visualized by plotting the three-dimensional dependence of the Young's moduli
+on the direction in the crystal lattice. The obtained results, which are
+reported for the first time to the best of the author's knowledge, can
+facilitate assessment of possible applications of the title material.",1306.2063v1
+2013-06-11,Localization at the Edge of 2D Topological Insulator by Kondo Impurities with Random Anisotropies,"We consider chiral electrons moving along the 1D helical edge of a 2D
+topological insulator and interacting with a disordered chain of Kondo
+impurities. Assuming the electron-spin couplings of random anisotropies, we map
+this system to the problem of the pinning of the charge density wave by the
+disordered potential. This mapping proves that arbitrary weak anisotropic
+disorder in coupling of chiral electrons with spin impurities leads to the
+Anderson localization of the edge states.",1306.2626v3
+2013-06-18,Anisotropy in solid inflation,"In the model of solid / elastic inflation, inflation is driven by a source
+that has the field theoretical description of a solid. To allow for prolonged
+slow roll inflation, the solid needs to be extremely insensitive to the spatial
+expansion. We point out that, because of this property, the solid is also
+rather inefficient in erasing anisotropic deformations of the geometry. This
+allows for a prolonged inflationary anisotropic solution, providing the first
+example with standard gravity and scalar fields only which evades the
+conditions of the so called cosmic no-hair conjecture. We compute the curvature
+perturbations on the anisotropic solution, and the corresponding
+phenomenological bound on the anisotropy. Finally, we discuss the analogy
+between this model and the f (phi) F^2 model, which also allows for anisotropic
+inflation thanks to a suitable coupling between the inflaton phi and a vector
+field. We remark that the bispectrum of the curvature perturbations in solid
+inflation is enhanced in the squeezed limit and presents a nontrivial angular
+dependence, as had previously been found for the f (phi) F^2 model.",1306.4160v1
+2013-06-21,Two-point correlation function of density perturbations in a large void universe,"We study the two-point correlation function of density perturbations in a
+spherically symmetric void universe model which does not employ the Copernican
+principle. First we solve perturbation equations in the inhomogeneous universe
+model and obtain density fluctuations by using a method of non-linear
+perturbation theory which was adopted in our previous paper. From the obtained
+solutions, we calculate the two-point correlation function and show that it has
+a local anisotropy at the off-center position differently from those in
+homogeneous and isotropic universes. This anisotropy is caused by the tidal
+force in the off-center region of the spherical void. Since no tidal force
+exists in homogeneous and isotropic universes, we may test the inhomogeneous
+universe by observing statistical distortion of the two-point galaxy
+correlation function.",1306.5131v1
+2013-06-21,Magnetic properties of a family of quinternary oxalates,"We report on the magnetic properties of four isomorphous compounds of a
+family of quinternary oxalates down to 60 mK. In all these materials, the
+magnetic FeII ions with a strong magneto-crystalline anisotropy form a
+distorted kagome lattice, topologically equivalent to a perfect kagome one if
+nearest-neighbor interactions only are considered. All the compounds order at
+low temperature in an antiferromagnetic arrangement with magnetic moments at
+120{\deg}. A remarkable magnetic behavior emerges below the N\'eel temperature
+in three compounds (with inter-kagome-layer Zr, Sn, Fe but not with Al): the
+spin anisotropy combined with a low exchange path network connectivity lead to
+domain walls intersecting the kagome planes through strings of free spins.
+These produce an unfamiliar slow spin dynamics in the ordered phase observed by
+AC susceptibility, evolving from exchange-released spin-flips towards a
+cooperative behavior on decreasing the temperature.",1306.5188v1
+2013-06-21,Change of magnetic ground state by light electron-doping in CeOs2Al10,"The effect of Ir substitution for Os in CeOs2Al10, with an unusually high
+Neel temperature of T~28.5K, has been studied by high-resolution neutron
+diffraction and magnetization measurements. A small amount of Ir (~ 8%) results
+in a pronounced change of the magnetic structure of the Ce-sublattice. The new
+magnetic ground state is controlled by the single ion anisotropy and implies
+antiferromagnetic arrangement of the Ce-moments along the a-axis, as expected
+from the anisotropy of the paramagnetic susceptibility. The value of the
+ordered moments, 0.92(1) mu_B, is substantially bigger than in the undoped
+compound, whereas the transition temperature is reduced down to 21K. A
+comparison of the observed phenomena with the recently studied CeRu1.9Rh0.1Al10
+system, exhibiting similar behaviour [A. Kondo et al., J. Phys. Soc. Jpn. 82,
+054709 (2013)], strongly suggests the electron doping as the main origin of the
+ground state changes. This provides a new way of exploring the anomalous
+magnetic properties of the Ce(Ru/Os)2Al10 compounds.",1306.5269v1
+2013-06-24,Orientation of the Angular Momentum in Superfluid 3He-A in a Stretched Aerogel,"Superfluid 3He-A in a fully characterized stretched aerogel, used in previous
+work [1], has been studied for parallel and perpendicular orientations of the
+magnetic field relative to the anisotropy axis of the aerogel. Consistently, we
+find that an equal spin pairing state (ESP) is stabilized down to the lowest
+temperature. From our pulsed NMR frequency shifts as a function of temperature
+and tip angle, the orientation of the orbital angular momentum l has been
+determined. The aerogel anisotropy introduced by uniaxial stretching tends to
+align l in the axial state parallel to the strain axis, confirming the theory
+proposed by Sauls [2] and contrary to the prediction of Volovik [3] based on an
+impurity calculation of Rainer and Vuorio [4].",1306.5783v1
+2013-06-27,Proton Kinetic Effects in Vlasov and Solar Wind Turbulence,"Kinetic plasma processes have been investigated in the framework of solar
+wind turbulence, employing Hybrid Vlasov-Maxwell (HVM) simulations. The
+dependency of proton temperature anisotropy T_{\perp}/T_{\parallel} on the
+parallel plasma beta \beta_{\parallel}, commonly observed in spacecraft data,
+has been recovered using an ensemble of HVM simulations. By varying plasma
+parameters, such as plasma beta and fluctuation level, the simulations explore
+distinct regions of the parameter space given by T_{\perp}/T_{\parallel} and
+\beta_{\parallel}, similar to solar wind sub-datasets. Moreover, both
+simulation and solar wind data suggest that temperature anisotropy is not only
+associated with magnetic intermittent events, but also with gradient-type
+structures in the flow and in the density. This connection between
+non-Maxwellian kinetic effects and various types of intermittency may be a key
+point for understanding the complex nature of plasma turbulence.",1306.6455v1
+2013-06-28,"The role of orbital order in the stabilization of the $(π,0)$ ordered magnetic state in a minimal two-band model for iron pnictides","Spin wave excitations and stability of the ($\pi,0$) ordered magnetic state
+are investigated in a minimal two-band itinerant-electron model for iron
+pnictides. Presence of hopping anisotropy generates a strong ferro-orbital
+order in the $d_{xz}$ and $d_{yz}$ Fe orbitals. The orbital order sign is as
+observed in experiments. The induced ferro-orbital order strongly enhances the
+spin wave energy scale and stabilizes the magnetic state by optimizing the
+strength of the emergent AF and F spin couplings through optimal band fillings
+in the two orbitals. The calculated spin-wave dispersion is in quantitative
+agreement with neutron scattering measurements. Finite inter-orbital Hund's
+coupling is shown to further enhance the spin wave energies state by coupling
+the two magnetic sub-systems. A more realistic two-band model with less hopping
+anisotropy is also considered which yields not only the circular hole pockets,
+also correct ferro-orbital order and emergent F spin coupling.",1306.6727v2
+2013-07-03,Leaky mode analysis of luminescent thin films: the case of ZnO on sapphire,"Zinc oxide (ZnO) epitaxial thin films grown on c-sapphire substrates by
+pulsed laser deposition were investigated using angle and polarization-resolved
+photoluminescence spectroscopy. Side-emission spectra differed significantly
+from surface-emission spectra in exhibiting dominant, narrow,
+polarization-resolved peaks. These spectral features were attributed to leaky
+substrate modes in the layers. Observations were first verified using
+transmission calculations with non-adjustable parameters, which took into
+account the dispersion, the anisotropy of the ZnO refractive index and the
+dependence on film thickness. Results were consistent with Fabry-Perot-like
+interference being the origin of the distinctive ZnO luminescence observed at
+grazing incidence angles. A second analysis, based on the source terms method,
+was used in order to retrieve the bulk emission properties, including the
+wavelength-dependent quantum yield and the emission anisotropy. While ZnO thin
+films were considered here, this analysis method can be extended to any
+luminescent thin film of similar geometry, demonstrating the potential of leaky
+mode analysis for probing passive and active material properties.",1307.0892v1
+2013-07-10,New limits on the violation of local position invariance of gravity,"Within the parameterized post-Newtonian (PPN) formalism, there could be an
+anisotropy of local gravity induced by an external matter distribution, even
+for a fully conservative metric theory of gravity. It reflects the breakdown of
+the local position invariance of gravity and, within the PPN formalism, is
+characterized by the Whitehead parameter $\xi$. We present three different
+kinds of observation, from the Solar system and radio pulsars, to constrain it.
+The most stringent limit comes from recent results on the extremely stable
+pulse profiles of solitary millisecond pulsars, that gives $|\hat \xi| < 3.9
+\times 10^{-9}$ (95% CL), where the hat denotes the strong-field generalization
+of $\xi$. This limit is six orders of magnitude more constraining than the
+current best limit from superconducting gravimeter experiments. It can be
+converted into an upper limit of $\sim 4 \times 10^{-16}$ on the spatial
+anisotropy of the gravitational constant.",1307.2637v1
+2013-07-17,Anisotropy-driven spin relaxation in germanium,"A unique spin depolarization mechanism, induced by the presence of g-factor
+anisotropy and intervalley scattering, is revealed by spin transport
+measurements on long-distance germanium devices in a longitudinal magnetic
+field. The confluence of electron-phonon scattering (leading to Elliott-Yafet
+spin flips) and this previously unobserved physics enables the extraction of
+spin lifetime solely from spin-valve measurements, without spin precession, and
+in a regime of substantial electric-field-generated carrier heating. We find
+spin lifetimes in Ge up to several hundreds of ns at low temperature, far
+beyond any other available experimental results.",1307.4745v3
+2013-07-19,Pseudoscalar N-flation and axial coupling revisited,"We revisit the dynamics of the axial coupling between many N-flatons and an
+Abelian gauge field, with special attention to its statistically anisotropic
+signal. The anisotropic power spectrum of curvature perturbations associated to
+the large wavelength modes of the gauge vector field is generally undetectable,
+since the anisotropy is confined to small scales. If the gauge field is the
+electromagnetic field, provided that the number of fields participating in the
+exponential expansion is large, it could be possible to generate sizable large
+scale magnetic fields. However, its spectrum is blue, and appreciable power on
+large scales implies an overly strong field on smaller scales, incompatibly
+with observations. Furthermore, the anisotropy is also markedly enhanced, and
+might be at odds with the isotropic observed sky. These aspects further demand
+that the scale of inflation is kept to a minimum.",1307.5215v3
+2013-07-23,Anisotropic Infrared Response of Vanadium Dioxide Microcrystals,"Vanadium dioxide (VO2) undergoes a phase transition at a temperature of 340 K
+between an insulating monoclinic M1 phase and a conducting rutile phase.
+Accurate measurements of possible anisotropy of the electronic properties and
+phonon features of VO2 in the insulating monoclinic M1 and metallic rutile
+phases are a prerequisite for understanding the phase transition in this
+correlated system. Recently, it has become possible to grow single domain
+untwinned VO2 microcrystals which makes it possible to investigate the true
+anisotropy of VO2. We performed polarized transmission infrared
+micro-spectroscopy on these untwinned microcrystals in the spectral range
+between 200 cm-1 and 6000 cm-1 and have obtained the anisotropic phonon
+parameters and low frequency electronic properties in the insulating monoclinic
+M1 and metallic rutile phases. We have also performed ab initio GGA+U total
+energy calculations of phonon frequencies for both phases. We find our
+measurements and calculations to be in good agreement.",1307.6022v1
+2013-07-29,Current-induced spin wave excitation in Pt|YIG bilayer,"We develop a self-consistent theory for current-induced spin wave excitations
+in normal metal-magnetic insulator bilayer systems, thereby establishing the
+relation between spin wave excitation and the experimentally controlled
+parameters. We fully take into account the complex spin wave spectrum including
+dipolar interactions and surface anisotropy as well as the spin-pumping at the
+interface. Our results focus on the mode-dependent power close to the critical
+currents for spin wave excitation. The major findings are (a) the spin transfer
+torque can excite different spin-wave modes simultaneously; (b) spin pumping
+counterbalances spin-transfer torque and affects the surface modes more than
+the bulk modes; (c) spin pumping inhibits high frequency spin-wave modes,
+thereby redshifting the excitation spectrum. We can get agreement with
+experiments on yttrium iron garnet|platinum bilayers by postulating the
+existence of surface anisotropy modes.",1307.7607v2
+2013-07-30,Evidence for exclusion of the possibility of $d$-wave superconducting-gap symmetry in Ba-doped KFe$_2$As$_2$,"We have investigated the superconducting(SC)-gap anisotropy for several
+Ba-doped KFe$_2$As$_2$ samples using laser-based angle-resolved photoemission
+spectroscopy. We show that the SC-gap anisotropy and node positions drastically
+change with a small amount of Ba doping. Our results totally exclude a
+possibility of $d$-wave symmetry and strongly suggest that both spin and
+orbital fluctuations are important for the paring interaction in the Ba-doped
+K122.",1307.7922v3
+2013-07-31,"Cosmic ray Spectrum, Composition, and Anisotropy Measured with IceCube","Analysis of cosmic ray surface data collected with the IceTop array of
+Cherenkov detectors at the South Pole provides an accurate measurement of the
+cosmic ray spectrum and its features in the ""knee"" region up to energies of
+about 1 EeV. IceTop is part of the IceCube Observatory that includes a deep-ice
+cubic kilometer detector that registers signals of penetrating muons and other
+particles. Surface and in-ice signals detected in coincidence provide clear
+insights into the nuclear composition of cosmic rays. IceCube already measured
+an increase of the average primary mass as a function of energy. We present
+preliminary results on both IceTop-only and coincident event analyses.
+Furthermore, we review the recent measurement of the cosmic ray anisotropy with
+IceCube.",1307.8394v1
+2013-08-02,Temperature-dependent exchange bias properties of polycrystalline PtxCo1-x/CoO bilayers,"Temperature and PtCo composition dependence of exchange bias in PtxCo1-x/CoO
+bilayers is investigated. It is observed that exchange bias properties,
+blocking temperature and magnetic anisotropy of the PtxCo1-x/CoO thin films are
+strongly affected by the concentration of Pt at the common interface. A
+detailed structural analysis of antiferromagnetic CoO has been done by x-ray
+photoelectron spectroscopy (XPS). The XPS data revealed that CoO layer grows
+with non-stoichiometric behavior which results in other cobalt oxide phases and
+thus lowers blocking temperature for the exchange biased systems. Increase of
+Pt concentration in PtCo layer strengths the exchange bias and thus decreases
+training of the system. It also results in enhancement of growth-induced
+uniaxial magnetic anisotropy and onset of exchange bias at higher temperatures.
+The role of Pt concentration on the interfacial interactions between
+ferromagnetic and antiferromagnetic layers, and the effect of
+superstoichiometric CoO on blocking temperature are also discussed.",1308.0483v1
+2013-08-09,Ground state phase diagram of the 2d Bose-Hubbard model with anisotropic hopping,"We compute the ground state phase diagram of the 2d Bose-Hubbard model with
+anisotropic hopping using quantum Monte Carlo simulations, connecting the 1d to
+the 2d system. We find that the tip of the lobe lies on a curve controlled by
+the 1d limit over the full anisotropy range while the universality class is
+always the same as in the isotropic 2d system. This behavior can be derived
+analytically from the lowest RG equations and has a form typical for the
+underlying Kosterlitz-Thouless transition in 1d. We also compute the phase
+boundary of the Mott lobe for strong anisotropy and compare it to the 1d
+system. Our calculations shed light on recent cold gas experiments monitoring
+the dynamics of an expanding cloud.",1308.2229v2
+2013-08-10,A longwave model for strongly anisotropic growth of a crystal step,"A continuum model for the dynamics of a single step with the strongly
+anisotropic line energy is formulated and analyzed. The step grows by
+attachment of adatoms from the lower terrace, onto which atoms adsorb from a
+vapor phase or from a molecular beam, and the desorption is non-negligible (the
+""one-sided"" model). Via a multi-scale expansion, we derived a longwave,
+strongly nonlinear, and strongly anisotropic evolution PDE for the step
+profile. Written in terms of the step slope, the PDE can be represented in the
+form similar to a convective Cahn-Hilliard equation. We performed the linear
+stability analysis and computed the nonlinear dynamics. Linear stability
+depends on whether the stiffness is minimum or maximum in the direction of the
+step growth. It also depends nontrivially on the combination of the anisotropy
+strength parameter and the atomic flux from the terrace to the step.
+Computations show formation and coarsening of a hill-and-valley structure
+superimposed onto a large-wavelength profile, which independently coarsens.
+Coarsening laws for the hill-and-valley structure are computed for two
+principal orientations of a maximum step stiffness, the increasing anisotropy
+strength, and the varying atomic flux.",1308.2308v1
+2013-08-11,Proton Kinetic Effects and Turbulent Energy Cascade Rate in the Solar Wind,"The first observed connection between kinetic instabilities driven by proton
+temperature anisotropy and estimated energy cascade rates in the turbulent
+solar wind is reported using measurements from the Wind spacecraft at 1 AU. We
+find enhanced cascade rates are concentrated along the boundaries of the
+($\beta_{\parallel}$, $T_{\perp}/T_{\parallel}$)-plane, which includes regions
+theoretically unstable to the mirror and firehose instabilities. A strong
+correlation is observed between the estimated cascade rate and kinetic effects
+such as temperature anisotropy and plasma heating, resulting in protons 5-6
+times hotter and 70-90% more anisotropic than under typical isotropic plasma
+conditions. These results offer new insights into kinetic processes in a
+turbulent regime.",1308.2425v1
+2013-08-13,Doping influence of spin dynamics and magnetoelectric effect in hexagonal Y$_{0.7}$Lu$_{0.3}$MnO$_{3}$,"We use inelastic neutron scattering to study spin waves and their correlation
+with the magnetoelectric effect in Y$_{0.7}$Lu$_{0.3}$MnO$_3$. In the undoped
+YMnO$_3$ and LuMnO$_3$, the Mn trimerization distortion has been suggested to
+play a key role in determining the magnetic structure and the magnetoelectric
+effect. In Y$_{0.7}$Lu$_{0.3}$MnO$_3$, we find a much smaller in-plane
+(hexagonal $ab$-plane) single ion anisotropy gap that coincides with a weaker
+in-plane dielectric anomaly at $T_N$. Since both the smaller in-plane
+anisotropy gap and the weaker in-plane dielectric anomaly are coupled to a
+weaker Mn trimerization distortion in Y$_{0.7}$Lu$_{0.3}$MnO$_3$ comparing to
+YMnO$_3$ and LuMnO$_3$, we conclude that the Mn trimerization is responsible
+for the magnetoelectric effect and multiferroic phenomenon in
+Y$_{1-y}$Lu$_{y}$MnO$_{3}$.",1308.2908v1
+2013-08-14,Nonperturbative analysis of the evolution of cosmological perturbations through a nonsingular bounce,"In bouncing cosmology, the primordial fluctuations are generated in a cosmic
+contraction phase before the bounce into the current expansion phase. For a
+nonsingular bounce, curvature and anisotropy grow rapidly during the bouncing
+phase, raising questions about the reliability of perturbative analysis. In
+this paper, we study the evolution of adiabatic perturbations in a nonsingular
+bounce by nonperturbative methods including numerical simulations of the
+nonsingular bounce and the covariant formalism for calculating nonlinear
+perturbations. We show that the bounce is disrupted in regions of the universe
+with significant inhomogeneity and anisotropy over the background energy
+density, but is achieved in regions that are relatively homogeneous and
+isotropic. Sufficiently small perturbations, consistent with observational
+constraints, can pass through the nonsingular bounce with negligible alteration
+from nonlinearity. We follow scale invariant perturbations generated in a
+matter-like contraction phase through the bounce. Their amplitude in the
+expansion phase is determined by the growing mode in the contraction phase, and
+the scale invariance is well preserved across the bounce.",1308.3044v1
+2013-08-20,Hole Spin Helix: Anomalous Spin Diffusion in Anisotropic Strained Hole Quantum Wells,"We obtain the spin-orbit interaction and spin-charge coupled transport
+equations of a two-dimensional heavy hole gas under the influence of strain and
+anisotropy. We show that a simple two-band Hamiltonian can be used to describe
+the holes. In addition to the well-known cubic hole spin-orbit interaction,
+anisotropy causes a Dresselhaus-like term, and strain causes a Rashba term. We
+discover that strain can cause a shifting symmetry of the Fermi surfaces for
+spin up and down holes. We predict an enhanced spin lifetime associated with a
+spin helix standing wave similar to the Persistent Spin Helix which exists in
+the two-dimensional electron gas with equal Rashba and Dresselhaus spin-orbit
+interactions. These results may be useful both for spin-based experimental
+determination of the Luttinger parameters of the valence band Hamiltonian and
+for creating long-lived spin excitations.",1308.4248v3
+2013-08-21,Thermal power spectrum in the CFT driven cosmology,"We present an overview of the recently suggested cosmological model driven by
+conformal field theory (CFT) with the initial conditions in the form of the
+microcanonical density matrix. In particular, we discuss the origin of
+inflationary stage in this model and a novel feature -- the thermal nature of
+the primordial power spectrum of the CMB anisotropy. The relevant effect of
+""temperature of the relic temperature anisotropy"" can be responsible for a
+thermal contribution to the red tilt of this spectrum, additional to its
+conventional vacuum component. The amplification of this effect due to recently
+established $a$-theorem in CFT is briefly discussed.",1308.4451v2
+2013-08-22,Confined dissipative droplet solitons in spin-valve nanowires with perpendicular magnetic anisotropy,"Magnetic dissipative droplets are localized, strongly nonlinear dynamical
+modes excited in nano-contact spin valves with perpendicular magnetic
+anisotropy. These modes find potential application in nanoscale structures for
+magnetic storage and computation, but dissipative droplet studies have so far
+been limited to extended thin films. Here, numerical and asymptotic analyses
+are used to demonstrate the existence and properties of novel solitons in
+confined structures. As a nanowire's width is decreased with a nano-contact of
+fixed size at its center, the observed modes undergo transitions from a fully
+localized two-dimensional droplet into a two-dimensional droplet edge mode and
+then a pulsating one-dimensional droplet. These solitons are interpreted as
+dissipative versions of classical, conservative solitons, allowing for an
+analytical description of the modes and the mechanisms of bifurcation. The
+presented results open up new possibilities for the study of low-dimensional
+solitons and droplet applications in nanostructures.",1308.4812v1
+2013-08-27,Multiple scattering Sunyaev-Zeldovich signal I: lowest order effect,"Future high-resolution, high-sensitivity Sunyaev-Zeldovich (SZ) observations
+of individual clusters will allow us to study the dynamical state of the intra
+cluster medium (ICM). To exploit the full potential of this new observational
+window, it is crucial to understand the different contributions to the total SZ
+signal. Here, we investigate the signature caused by multiple scatterings at
+lowest order of the electron temperature. Previous analytic discussions of this
+problem used the isotropic scattering approximation (ISA), which even for the
+simplest cluster geometries is rather rough. We take a step forward and
+consistently treat the anisotropy of the ambient radiation field caused by the
+first scattering. We show that the multiple scattering SZ signal directly
+probes line of sight anisotropies of the ICM, thereby delivering a new set of
+SZ observables which could be used for 3D cluster-profile reconstruction. The
+multiple scattering signal should furthermore correlate spatially with the
+cluster's X-ray and SZ polarization signals, an effect that could allow
+enhancing the detectability of this contribution.",1308.5969v2
+2013-08-28,Tunneling spectroscopy for probing orbital anisotropy in iron pnictides,"Using realistic multi-orbital tight-binding Hamiltonians and the T-matrix
+formalism, we explore the effects of a non-magnetic impurity on the local
+density of states in Fe-based compounds. We show that scanning tunneling
+spectroscopy (STS) has very specific anisotropic signatures that track the
+evolution of orbital splitting (OS) and antiferromagnetic gaps. Both
+anisotropies exhibit two patterns that split in energy with decreasing
+temperature, but for OS these two patterns map onto each other under 90 degree
+rotation. STS experiments that observe these signatures should expose the
+underlying magnetic and orbital order as a function of temperature across
+various phase transitions.",1308.6248v2
+2013-09-01,The orientation dependence of quasar spectral energy distributions,"We investigate the orientation dependence of the spectral energy
+distributions in a sample of radio-loud quasars. Selected specifically to study
+orientation issues, the sample contains 52 sources with redshifts in the range
+0.16<z<1.4 and measurements of radio core dominance, a radio orientation
+indicator. Measured properties include monochromatic luminosities at a range of
+wavelengths between the infrared and X-rays, integrated infrared luminosity,
+spectral slopes, and the covering fraction of the obscuring circumnuclear dust.
+We estimate dust covering fraction assuming that the accretion disk emits
+anisotropically and discuss the shortcomings and technical difficulties of this
+calculation. Luminosities are found to depend on orientation, with face-on
+sources factors of a 2-3 brighter than more edge-on sources, depending on
+wavelength. The degree of anisotropy varies very little with wavelength such
+that the overall shape of the spectral energy distribution does not vary
+significantly with orientation. In the infrared, we do not observe a decrease
+in anisotropy with increasing wavelength. The spectral slopes and estimates of
+covering fraction are not significantly orientation dependent. We construct
+composite spectral energy distributions as a function of radio core dominance
+and find that these illustrate the results determined from the measured
+properties.",1309.0182v1
+2013-09-02,Recent progress in perpendicularly magnetized Mn-based binary alloy films,"In this article, we review the recent progress in growth, structural
+characterization, magnetic properties and related spintronic devices of
+tetragonal MnxGa and MnxAl thin films with perpendicular magnetic anisotropy.
+In the first part of this review, we present a brief introduction to the
+demands for perpendicularly magnetized materials in spintronics, magnetic
+recording and permanent magnets applications, and the most promising candidates
+of tetragonal MnxGa and MnxAl with strong perpendicular anisotropy. Then, in
+the second and third parts, we focus on the recent progress of perpendicularly
+magnetized MnxGa and MnxAl, respectively, including their lattice structures,
+bulk synthesis, epitaxial growth, structural chracterizations, magnetic and
+other spin-dependent properties, and spintronic devices like magnetic tunneling
+junctions, spin valves and spin injector into semiconductors. Finally, we give
+a summary and a perspective of these perpendicularly magnetized Mn-based binary
+alloy films for future applications.",1309.0298v2
+2013-09-02,Ground-state fidelity of the spin-1 Heisenberg chain with single ion anisotropy: quantum renormalization group and exact diagonalization approaches,"We study the phase diagram of the anisotropic spin-1 Heisenberg chain with
+single ion anisotropy (D) using a ground-state fidelity approach. The
+ground-state fidelity and its corresponding susceptibility are calculated
+within the quantum renormalization group scheme where we obtained the
+renormalization of fidelity preventing to calculate the ground state. Using
+this approach, the phase boundaries between the antiferromagnetic N\'{e}el,
+Haldane and large-D phases are obtained for the whole phase diagram, which
+justifies the application of quantum renormalization group to trace the
+symmetery protected topological phases. In addition, we present numerical exact
+diagonalization (Lanczos) results in, which we employ a recently introduced
+non-local order parameter to locate the transition from Haldane to large-D
+phase accurately.",1309.0402v1
+2013-09-04,Structural anisotropy of directionally dried colloids,"Aqueous colloidal dispersions of silica particles become anisotropic when
+they are dried through evaporation. This anisotropy is generated by a uniaxial
+strain of the liquid dispersions as they are compressed by the flow of water
+toward a solidification front. Part of the strain produced by the compression
+is relaxed, and part of it is stored and transferred to the solid. This stored
+elastic strain has consequences for the properties of the solid, where it may
+facilitate the growth of shear bands, and generate birefringence.",1309.1048v2
+2013-09-05,Measurements of cosmic rays at the highest energies with the Pierre Auger Observatory,"This paper summarizes the status and the recent measurements from the Pierre
+Auger Observatory. The energy spectrum is described and its features discussed.
+We report searches for anisotropy of cosmic ray arrival directions on large
+scales and through correlation with catalogues of celestial objects. We also
+present the search for anisotropies in the data without the use of astronomical
+catalogues. The first measurement of the proton-air cross section around
+10^{18} eV is discussed. Finally, the mass composition is addressed with
+measurements of the variation of the depth of shower maximum with energy and
+with the muon density at ground.",1309.1249v1
+2013-09-07,Anisotropy in Cosmic rays from internal transitions in neutron stars,"We discuss the possibility that some recently measured anisotropic cosmic ray
+components in the TeV-PeV energy range may be an indication of the ejection of
+a peculiar type of matter. We present a model where a neutron star internal
+transition with nuclear deconfinement of the quark content takes place. This
+catastrophic event may cause a mass ejection process seeding the insterstelar
+medium with droplets of quark matter, so called nuclearites. Neutralization of
+these droplets in molecular clouds may drive the anisotropy since
+quasi-rectilinear trajectories are allowed. Complementary information from
+current experimental settings on earth or magnetic spectrometers on the ISS may
+shed light on this exotic form of matter.",1309.1852v1
+2013-09-20,Nonlocal Granular Rheology: Role of Pressure and Anisotropy,"We probe the secondary rheology of granular media, by imposing a main flow
+and immersing a vane-shaped probe into the slowly flowing granulate. The
+secondary rheology is then the relation between the exerted torque T and
+rotation rate \omega of our probe. In the absence of any main flow, the probe
+experiences a clear yield-stress, whereas for any finite flow rate, the yield
+stress disappears and the secondary rheology takes on the form of a double
+exponential relation between \omega and T. This secondary rheology does not
+only depend on the magnitude of T, but is anisotropic --- which we show by
+varying the relative orientation of the probe and main flow. By studying the
+depth dependence of the three characteristic torques that characterize the
+secondary rheology, we show that for counter flow, the dominant contribution is
+frictional like --- i.e., T and pressure are proportional for given \omega ---
+whereas for co flow, the situation is more complex. Our experiments thus reveal
+the crucial role of anisotropy for the rheology of granular media.",1309.5238v1
+2013-09-21,Spin excitations of individual Fe atoms on Pt(111): impact of the site-dependent giant substrate polarization,"We demonstrate using inelastic scanning tunneling spectroscopy (ISTS) and
+simulations based on density functional theory that the amplitude and sign of
+the magnetic anisotropy energy for a single Fe atom adsorbed onto the Pt(111)
+surface can be manipulated by modifying the adatom binding site. Since the
+magnitude of the measured anisotropy is remarkably small, up to an order of
+magnitude smaller than previously reported, electron-hole excitations are weak
+and thus the spin-excitation exhibits long lived precessional lifetimes
+compared to the values found for the same adatom on noble metal surfaces.",1309.5443v1
+2013-09-17,Radical-pair model of magnetoreception with spin-orbit coupling,"The mechanism used by migratory birds to orientate themselves using the
+geomagnetic field is still a mystery in many species. The radical pair
+mechanism, in which very weak magnetic fields can influence certain types of
+spin-dependent chemical reactions, leading to biologically observable signals,
+has recently imposed itself as one of the most promising candidates for certain
+species. This is thanks both to its extreme sensitivity and its capacity to
+reproduce results from behavioral studies. Still, in order to gain a
+directional sensitivity, an anisotropic mechanism is needed. Recent proposals
+have explored the possibility that such an anisotropy is due to the
+electron-nucleus hyperfine interaction. In this work we explore a different
+possibility, in which the anisotropy is due to spin-orbit coupling between the
+electron spin and its angular momentum. We will show how a
+spin-orbit-coupling-based magnetic compass can have performances comparable
+with the usually-studied nuclear-hyperfine based mechanism. Our results could
+thus help researchers actively looking for candidate biological molecules which
+may host magnetoreceptive functions, both to describe magnetoreception in birds
+as well as to develop artificial chemical compass systems.",1309.5882v1
+2013-09-25,Acausality and Nonunique Evolution in Generalized Teleparallel Gravity,"We show the existence of physical superluminal modes and acausality in the
+Brans-Dicke type of extension of teleparallel gravity that includes F(T)
+gravity and teleparallel dark energy as special cases. We derive the
+characteristic hypersurface for the extra degrees of freedom in the theory,
+thereby showing that the time evolution is not unique and closed causal curves
+can appear. Furthermore, we present a concrete disastrous solution in Bianchi
+type I spacetime, in which the anisotropy in expansion can be any function of
+time, and thus anisotropy can emerge suddenly, a simple demonstration that the
+theory is physically problematic.",1309.6461v2
+2013-09-25,Generating Intrinsic Dipole Anisotropy in the Large Scale Structures,"There have been recent reports of unexpectedly large velocity dipole in the
+NRAO VLA Sky Survey data. We investigate whether the excess in the NVSS dipole
+reported can be of cosmological origin. We assume a long wavelength
+inhomogeneous scalar perturbation of the form \alpha sin (\kappa z) and study
+its effects on the matter density contrasts. Assuming an ideal fluid model we
+calculate, in the linear regime, the contribution of the inhomogeneous mode to
+the density contrast. We calculate the expected dipole in the LSS for two
+cases, first assuming that the mode is still superhorizon everywhere, and
+second assuming the mode is subhorizon, but has crossed the horizon deep in
+matter domination and is subhorizon everywhere in the region of the survey
+(NVSS). In both cases we find that such an inhomogeneous scalar perturbation is
+sufficient to generate the reported values of dipole anisotropy in LSS. For the
+superhorizon modes we find values which are consistent with both CMB and NVSS
+results. We also predict signatures for the model which can be tested by future
+observations.",1309.6547v2
+2013-09-26,Anisotropic two-dimensional electron gas at SrTiO3(110) protected by its native overlayer,"Two dimensional electron gases (2DEGs) at a oxide heterostructures are
+attracting considerable attention, as these might substitute conventional
+semiconductors for novel electronic devices [1]. Here we present a minimal
+set-up for such a 2DEG -the SrTiO3(110)-(4 x 1) surface, natively terminated
+with one monolayer of chemically-inert titania. Oxygen vacancies induced by
+synchrotron radiation migrate under- neath this overlayer, this leads to a
+confining potential and electron doping such that a 2DEG develops. Our angular
+resolved photoemission spectroscopy (ARPES) and theoretical results show that
+confinement along (110) is strikingly different from a (001) crystal
+orientation. In particular the quantized subbands show a surprising
+""semi-heavy"" band, in contrast to the analogue in the bulk, and a high
+electronic anisotropy. This anisotropy and even the effective mass of the (110)
+2DEG is tunable by doping, offering a high flexibility to engineer the
+properties of this system.",1309.7042v1
+2013-09-29,Longitudinal spin excitations and magnetic anisotropy in antiferromagnetically ordered BaFe2As2,"We report on a spin-polarized inelastic neutron scattering study of spin
+waves in the antiferromagnetically ordered state of BaFe2As2. Three distinct
+excitation components are identified, with spins fluctuating along the c-axis,
+perpendicular to the ordering direction in the ab-plane, and parallel to the
+ordering direction. While the first two ""transverse"" components can be
+described by a linear spin-wave theory with magnetic anisotropy and inter-layer
+coupling, the third ""longitudinal"" component is generically incompatible with
+the local moment picture. It points towards a contribution of itinerant
+electrons to the magnetism already in the parent compound of this family of
+Fe-based superconductors.",1309.7553v1
+2013-09-30,"Robust Computation of Dipole Electromagnetic Fields in Arbitrarily-Anisotropic, Planar-Stratified Environments","We develop a general-purpose formulation, based on two-dimensional spectral
+integrals, for computing electromagnetic fields produced by
+arbitrarily-oriented dipoles in planar-stratified environments, where each
+layer may exhibit arbitrary and independent anisotropy in both the (complex)
+permittivity and permeability. Among the salient features of our formulation
+are (1) computation of eigenmodes (characteristic plane waves) supported in
+arbitrarily anisotropic media in a numerically robust fashion, (2)
+implementation of an hp-adaptive refinement for the numerical integration to
+evaluate the radiation and weakly-evanescent spectra contributions, and (3)
+development of an adaptive extension of an integral convergence acceleration
+technique to compute the strongly-evanescent spectrum contribution. While other
+semianalytic techniques exist to solve this problem, none have full
+applicability to media exhibiting arbitrary double anisotropies in each layer,
+where one must account for the whole range of possible phenomena such as mode
+coupling at interfaces and non-reciprocal mode propagation. Brute-force
+numerical methods can tackle this problem but only at a much higher
+computational cost. The present formulation provides an efficient and robust
+technique for field computation in arbitrary planar-stratified environments. We
+demonstrate the formulation for a number of problems related to geophysical
+exploration.",1309.7952v1
+2013-10-07,Double magnetic resonance and spin anisotropy in Fe-based superconductors due to static and fluctuating antiferromagnetic orders,"Motivated by recent neutron scattering experiments in Fe-based
+superconductors, we study how the magnetic resonance in the superconducting
+state is affected by the simultaneous presence of either static or fluctuating
+magnetic orders using the random phase approximation. We find that for the
+underdoped materials with coexisting superconducting and antiferromagnetic
+orders, spin rotational symmetry is explicitly broken at the ordering momentum
+$Q_1 = (\pi,0)$. Only the longitudinal susceptibility exhibits the resonance
+mode, whereas a spin-wave Goldstone mode develops in the transverse component.
+Meanwhile, at the frustrated momentum $Q_2 = (0,\pi)$, the susceptibility
+becomes isotropic in spin space and the magnetic resonance exists for both
+components. Furthermore, the resonance energies at $Q_1$ and $Q_2$ have
+distinct scales, which provides a natural explanation for the recently observed
+double resonance peaks. In addition, we show that near optimal doping the
+existence of strong magnetic fluctuations, which are modeled here via a
+Gaussian mode, can still induce the spin anisotropy in the magnetic
+susceptibility.",1310.1657v2
+2013-10-07,Isotropic Γ_6 Ground State in Caged Compound NdRu2Zn20,"The magnetic susceptibility $\chi$, the magnetization $M$, and the specific
+heat $C$ were measured for the caged cubic compound NdRu$_2$Zn$_{20}$ at
+temperatures down to 0.5 K in the magnetic field $H$ along the three
+crystallographic principal axes, [100], [110], and [111]. The ferromagnetic
+phase transition was observed at the Curie temperature $T_{\rm C}=1.9$ K in
+both the temperature dependence of $\chi(T)$ and $C(T)$. Below $T_{\rm C}$, the
+magnetization curves $M(H)$ show very weak magnetic anisotropy, and the $C(T)$
+curves in the fields along the three principal axes show no magnetic anisotropy
+both below and above $T_{\rm C}$. The easy direction of magnetization at 0.5 K
+changes from the [111] direction in 0 T to the [110] diretion in 7 T. We
+analyzed these characteristic behaviors theoretically taking into account the
+crystalline-electric-field energy, the magnetic exchange interaction, and the
+Zeeman energy. It was found that these features are originated from the
+isotropic $\Gamma_6$ ground state mixing with the magnetic $\Gamma_8^{(1)}$
+excited state. The temperature and the magnetic field dependences of $M(T,H)$
+and $C(T,H)$ are quantitatively well analyzed by this theoretical calculation.",1310.1664v1
+2013-10-09,Nematic Metal and Antiferromagnetic Insulator on Hexagonal Kagome Lattice,"Hexagonal Kagome lattice is a multiband system with a quadratic band crossing
+point, in contrast with honeycomb lattice with linear band crossing point,
+which has exotic correlated effect and can produce various novel quantum
+states. Here we investigate the phase diagram of the fermions on the hexagonal
+Kagome lattice as a function of interaction, temperature and lattice
+anisotropy, by combining the cellular dynamical mean-field theory with the
+continuous time quantum Monte Carlo method. For weak interaction, the quadratic
+band-crossing point is broken to linear band crossing point and the system is
+the semi-metal. With the increasing of the interaction, the system goes a first
+order transition to antiferromagnetic Mott insulator at low temperature. Below
+a critical temperature, due to the charge nematic fluctuation, a nematic metal
+forms between the weak coupling semi-metal and strong correlated Mott
+insulator. When the lattice anisotropy increases, the region of the nematic
+metal is enlarged. Furthermore, we discuss how to detect these phases in real
+experiments.",1310.2463v2
+2013-10-17,Double neutron spin resonances and gap anisotropy in underdoped superconducting NaFe0.985Co0.015As,"We use inelastic neutron scattering to show that superconductivity in
+electron-underdoped NaFe0.985Co0.015As induces a dispersive sharp resonance
+near Er1 = 3:25 meV and a broad dis- persionless mode at Er2 = 6 meV. However,
+similar measurements on overdoped superconducting NaFe0:955Co0:045As find only
+a single sharp resonance at Er = 7 meV. We connect these results with the
+observations of angle-resolved photoemission spectroscopy that the
+superconducting gaps in the electron Fermi pockets are anisotropic in the
+underdoped material but become isotropic in the overdoped case. Our analysis
+indicates that both the double neutron spin resonances and gap anisotropy
+originate from the orbital dependence of the superconducting pairing in the
+iron pnic- tides. Our discovery also shows the importance of the inelastic
+neutron scattering in detecting the multiorbital superconducting gap structures
+of iron pnictides.",1310.4817v1
+2013-10-17,Globular Cluster Scale Sizes in Giant Galaxies: The Case of M87 and the Role of Orbital Anisotropy and Tidal Filling,"We present new Hubble Space Telescope imaging of the outer regions of M87 in
+order to study its globular cluster (GC) population out to large galactocentric
+distances. We discuss particularly the relationship between GC effective radii
+$r_h$ and projected galactocentric distance $R_{gc}$. The observations suggest
+a shallow trend $r_h \propto R_{gc}^{0.14}$ out to $R_{gc} \sim 100$ kpc, in
+agreement with studies of other giant elliptical galaxies. To theoretically
+reproduce this relationship we simulate GC populations with various
+distributions of orbits. For an isotropic distribution of cluster orbits we
+find a steeper trend of $r_h \propto R_{gc}^{0.4}$. Instead we suggest that (a)
+if the cluster system has an orbital anisotropy profile, where orbits become
+preferentially radial with increasing galactocentric distance, AND (b) if
+clusters become more tidally under-filling with galactocentric distance, the
+observed relationship can be recovered. We also apply this approach to the red
+and blue GC populations separately and predict that red clusters are
+preferentially under-filling at large $R_{gc}$ and have a more isotropic
+distribution of orbits than blue clusters.",1310.4834v1
+2013-10-21,Anomalous Anisotropies of Cosmic Rays from Turbulent Magnetic Fields,"The propagation of cosmic rays (CRs) in turbulent interstellar magnetic
+fields is typically described as a spatial diffusion process. This formalism
+predicts only a small deviation from an isotropic CR distribution in the form
+of a dipole in the direction of the CR density gradient or relative background
+flow. We show that the existence of a global CR dipole moment necessarily
+generates a spectrum of higher multipole moments in the local CR distribution.
+These ""anomalous"" anisotropies are a direct consequence of Liouville's theorem
+in the presence of a local turbulent magnetic field. We show that the
+predictions of this model are in excellent agreement with the observed power
+spectrum of multi-TeV CRs.",1310.5712v2
+2013-10-23,"Unusual magneto-transport of YBa2Cu3O7-d films due to the interplay of anisotropy, random disorder and nanoscale periodic pinning","We study the general problem of a manifold of interacting elastic lines whose
+spatial correlations are strongly affected by the competition between random
+and ordered pinning. This is done through magneto-transport experiments with
+YBa2Cu3O7-d thin films that contain a periodic vortex pinning array created via
+masked ion irradiation, in addition to the native random pinning. The strong
+field-matching effects we observe suggest the prevalence of periodic pinning,
+and indicate that at the matching field each vortex line is bound to an
+artificial pinning site. However, the vortex-glass transition dimensionality,
+quasi-2D instead of the usual 3D, evidences reduced vortex-glass correlations
+along the vortex line. This is also supported by an unusual angular dependence
+of the magneto-resistance, which greatly differs from that of Bose-glass
+systems. A quantitative analysis of the angular magnetoresistance allows us to
+link this behaviour to the enhancement of the system anisotropy, a collateral
+effect of the ion irradiation.",1310.6165v1
+2013-10-31,Ground-State Phase Diagram of S=2 Heisenberg Chains with Alternating Single-Site Anisotropy,"The ground-state phase diagram of $S=2$ antiferromagnetic Heisenberg chains
+with coexisting uniform and alternating single-site anisotropies is
+investigated by the numerical exact diagonalization and density matrix
+renormalization group methods. We find the Haldane, large-$D$, N\'eel,
+period-doubled N\'eel, gapless spin fluid, quantized and partial ferrimagnetic
+phases. The Haldane phase is limited to the close neighborhood of the isotropic
+point. Within numerical accuracy, the transition from the gapless spin-fluid
+phase to the period-doubled N\'eel phase is a direct transition. Nevertheless,
+the presence of a narrow spin-gap phase between these two phases is suggested
+on the basis of the low-energy effective theory. The ferrimagnetic ground state
+is present in a wide parameter range. This suggests the realization of
+magnetized single-chain magnets with a uniform spin magnitude by controlling
+the environment of each magnetic ion without introducing ferromagnetic
+interactions.",1310.8586v2
+2013-10-31,Measurement of higher-order harmonic azimuthal anisotropy in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV,"Measurements are presented by the CMS Collaboration at the Large Hadron
+Collider (LHC) of the higher-order harmonic coefficients that describe the
+azimuthal anisotropy of charged particles emitted in sqrt(s[NN]) = 2.76 TeV
+PbPb collisions. Expressed in terms of the Fourier components of the azimuthal
+distribution, the n = 3-6 harmonic coefficients are presented for charged
+particles as a function of their transverse momentum (0.3 < pt < 8.0 GeV),
+collision centrality (0-70%), and pseudorapidity (abs(eta) < 2.0). The data are
+analyzed using the event plane, multiparticle cumulant, and Lee-Yang zeros
+methods, which provide different sensitivities to initial-state fluctuations.
+Taken together with earlier LHC measurements of elliptic flow (n = 2), the
+results on higher-order harmonic coefficients develop a more complete picture
+of the collective motion in high-energy heavy-ion collisions and shed light on
+the properties of the produced medium.",1310.8651v2
+2013-10-31,Two distinct spin liquid states in a layered cubic lattice,"We construct a family of short-range resonating-valence-bond wave functions
+on a layered cubic lattice, allowing for a tunable anisotropy in the amplitudes
+assigned to nearest-neighbour valence bonds along one axis. Monte Carlo
+simulations reveal that four phases are stabilized over the full range of the
+anisotropy parameter. They are separated from one another by a sequence of
+continuous quantum phase transitions. An antiferromagnetic phase, centred on
+the perfect isotropy point, intervenes between two distinct quantum spin liquid
+states. One of them is continuously deformable to the two-dimensional U(1) spin
+liquid, which is known to exhibit critical bond correlations. The other has
+both spin and bond correlations that decay exponentially. The existence of this
+second phase is proof that, contrary to expectations, neither a bipartite
+lattice structure nor a conventional Marshall sign rule is an impediment to
+realizing a fully gapped quantum spin liquid.",1311.0004v1
+2013-11-03,Defect-induced conductivity anisotropy in MoS2 monolayers,"Various types of defects in MoS2 monolayers and their influence on the
+electronic structure and transport properties have been studied using the
+Density-Functional based Tight-Binding method in conjunction with the Green's
+Function approach. Intrinsic defects in MoS2 monolayers significantly affect
+their electronic properties. Even at low concentration they considerably alter
+the quantum conductance. While the electron transport is practically isotropic
+in pristine MoS2, strong anisotropy is observed in the presence of defects.
+Localized mid-gap states are observed in semiconducting MoS2 that do not
+contribute to the conductivity but direction-dependent scatter the current, and
+that the conductivity is strongly reduced across line defects and selected
+grain boundary models.",1311.0474v3
+2013-11-06,Plan beta: Core or Cusp?,"The inner profile of Dark Matter (DM) halos remains one of the central
+problems in small-scale cosmology. At present, the problem can not be resolved
+in dwarf spheroidal galaxies due to a degeneracy between the DM profile and the
+velocity anisotropy beta of the stellar population. We discuss a method which
+can break the degeneracy by exploiting 3D positions and 1D line-of-sight (LOS)
+velocities. With the full 3D spatial information, we can determine precisely
+what fraction of each stars LOS motion is in the radial and tangential
+direction. This enables us to infer the anisotropy parameter beta directly from
+the data. The method is particularly effective if the galaxy is highly
+anisotropic. Finally, we argue that such a test could be applied to Sagittarius
+and potentially other dwarfs with RR Lyrae providing the necessary depth
+information.",1311.1522v2
+2013-11-13,Fokker-Planck approach to the theory of magnon-driven spin Seebeck effect,"Following the theoretical approach by Xiao et al [Phys. Rev. B 81, 214418
+(2010)] to the spin Seebeck effect, we calculate the mean value of the total
+spin current flowing through a normalmetal/ ferromagnet interface. The spin
+current emitted from the ferromagnet to the normal metal is evaluated in the
+framework of the Fokker-Planck approach for the stochastic
+Landau-Lifshitz-Gilbert equation. We show that the total spin current depends
+not only on the temperature difference between the electron and the magnon
+baths, but also on the external magnetic field and magnetic anisotropy. Apart
+from this, the spin current is shown to saturate with increasing magnon
+temperature, and the saturation temperature increases with increasing magnetic
+field and/or magnetic anisotropy.",1311.3117v1
+2013-11-13,Cosmic Microwave Background temperature and polarization anisotropies from the large-N limit of global defects,"We determine the full C_l spectra and correlation functions of the
+temperature and polarization anisotropies in the CMB, generated by a source
+modeled by the large N limit of spontaneously broken global O(N)-theories. We
+point out a problem in the standard approach of treating the radiation-matter
+transition by interpolating the eigenvectors of the unequal-time correlators of
+the source energy-momentum tensor. This affects the CMB predictions from all
+type of cosmic defects. We propose a method to overcome this difficulty, and
+find that in the large-N global model that we study, differences in the final
+CMB power spectra amplitudes reach up to 25%, when compared to implementations
+of the eigenvector interpolation technique. We discuss as well how to optimally
+search for the contribution in the CMB from active sources such as cosmic
+defects, in experiments like Planck, COrE and PRISM.",1311.3225v2
+2013-11-14,Critical current anisotropy in Nd-1111 single crystals and the infuence of neutron irradiation,"We report on angle-resolved magnetization measurements on
+NdFeAsO$_{0.65}$F$_{0.35}$ (Nd-1111) single crystals. The field dependence of
+the critical current density, $J_c$, is non-monotonous in these crystals at all
+orientations and temperatures due to the fishtail effect, which strongly
+influences the angular dependence of $J_c$. The currents decrease as the field
+is tilted from the crystallographic c-axis at low fields, but increase at high
+fields. A peak occurs in the angular dependence of $J_c$ at intermediate
+fields. The critical currents are significantly enhanced after irradiation with
+fast neutrons and the fishtail disappears. The different current anisotropies
+at low and high fields, however, persist. We discuss the data in the framework
+of the anisotropic scaling approach and propose a transition from dominant
+pinning by large defects of low density at low fields to pinning by small
+defects of high density at high fields in the pristine crystal. Strong pinning
+dominates at all fields after the irradiation, and the angular dependence of
+$J_c$ can be described by anisotropic scaling only after an appropriate
+extension to this pinning regime.",1311.3476v1
+2013-11-14,Topology beyond the horizon: how far can it be probed?,"The standard cosmological model does not determine the spatial topology of
+the universe. This article revisits the signature of a non-trivial topology on
+the properties of the cosmic microwave background anisotropies. We show that
+the correlation function of the coefficients of the expansion of the
+temperature and polarization anisotropies in spherical harmonics, encodes a
+topological signature that can be used to distinguish a multi-connected space
+from an infinite space on sizes larger than the last scattering surface. The
+effect of the instrumental noise and of a galactic cut are estimated. We thus
+establish boundaries for the size of the biggest torus dintinguisable with
+temperature and polarization CMB data. We also describe the imprint of the
+spatial topology on the 3-point function and on non-Gaussianity.",1311.3509v2
+2013-11-14,Nonequilibrium dynamics of a mixed spin-1/2 and spin-3/2 Ising ferrimagnetic system with a time dependent oscillating magnetic field source,"Nonequilibrium phase transition properties of a mixed Ising ferrimagnetic
+model consisting of spin-1/2 and spin-3/2 on a square lattice under the
+existence of a time dependent oscillating magnetic field have been investigated
+by making use of Monte Carlo simulations with single-spin flip Metropolis
+algorithm. A complete picture of dynamic phase boundary and magnetization
+profiles have been illustrated and the conditions of a dynamic compensation
+behavior have been discussed in detail. According to our simulation results,
+the considered system does not point out a dynamic compensation behavior, when
+it only includes the nearest-neighbor interaction, single-ion anisotropy and an
+oscillating magnetic field source. As the next-nearest-neighbor interaction
+between the spins-1/2 takes into account and exceeds a characteristic value
+which sensitively depends upon values of single-ion anisotropy and only of
+amplitude of external magnetic field, a dynamic compensation behavior occurs in
+the system. Finally, it is reported that it has not been found any evidence of
+dynamically first-order phase transition between dynamically ordered and
+disordered phases, which conflicts with the recently published molecular field
+investigation, for a wide range of selected system parameters.",1311.3537v2
+2013-11-15,Two-pulse field-free orientation reveals anisotropy of molecular shape resonance,"We report the observation of macroscopic field-free orientation, i.e. more
+than 73 % of CO molecules pointing in the same direction. This is achieved
+through an all-optical scheme operating at high particle densities
+($>10^{17}$cm$^{-3}$) that combines a one-color ($\omega$) and a two-color
+($\omega + 2\omega$) non-resonant femtosecond laser pulses. We show that the
+achieved orientation solely relies on the hyperpolarizability interaction as
+opposed to an ionization-depletion mechanism thus opening a wide range of
+applications. The achieved strong orientation enables us to reveal the
+molecular-frame anisotropies of the photorecombination amplitudes and phases
+caused by a shape resonance. The resonance appears as a local maximum in the
+even-harmonic emission around 28~eV. In contrast, the odd-harmonic emission is
+suppressed in this spectral region through the combined effects of an
+asymmetric photorecombination phase and a sub-cycle Stark effect, generic for
+polar molecules, that we experimentally identify.",1311.3923v2
+2013-11-16,Verification of Anisotropic s-Wave Superconducting Gap Structure in CeRu2 from Low-Temperature Field-Angle-Resolved Specific Heat Measurements,"The field-angle-resolved specific heat C(T,H,phi) of the f-electron
+superconductor CeRu2 (Tc=6.3 K) has been measured at low temperatures down to
+90 mK on two single crystals of slightly different qualities. We reveal that
+the C(phi) oscillation in a rotating magnetic field, originating from the gap
+anisotropy, diminishes at low temperatures below the characteristic field H*,
+as expected for an anisotropic gap without nodes. We also observe the
+suppression of H* by decreasing the gap anisotropy ratio $\Delta_{\rm
+min}/\Delta_{\rm max}$, a behavior that has been predicted from a microscopic
+theory for anisotropic s-wave superconductors. The present technique is
+established as a powerful tool for investigating minimum-gap structures as well
+as nodal structures.",1311.4050v1
+2013-11-20,Relaxation after quantum quenches in the spin-1/2 Heisenberg XXZ chain,"We consider the time evolution after quantum quenches in the spin-1/2
+Heisenberg XXZ quantum spin chain with Ising-like anisotropy. The time
+evolution of short-distance spin-spin correlation functions is studied by
+numerical tensor network techniques for a variety of initial states, including
+N\'eel and Majumdar-Ghosh states and the ground state of the XXZ chain at large
+values of the anisotropy. The various correlators appear to approach stationary
+values, which are found to be in good agreement with the results of exact
+calculations of stationary expectation values in appropriate generalized Gibbs
+ensembles. In particular, our analysis shows how symmetries of the post-quench
+Hamiltonian that are broken by particular initial states are restored at late
+times.",1311.5216v2
+2013-11-21,More on thermal probes of a strongly coupled anisotropic plasma,"We extend the analysis of 1211.2199, where the photon production rate of an
+anisotropic strongly coupled plasma with Nf<<Nc massless quarks was considered.
+We allow here for non-vanishing quark masses and study how these affect the
+spectral densities and conductivities. We also compute another important probe
+of the plasma, the dilepton production rate. We consider generic angles between
+the anisotropic direction and the photon and dilepton wave vectors, as well as
+arbitrary quark masses and arbitrary values of the anisotropy parameter.
+Generically, the anisotropy increases the production rate of both photons and
+dileptons, compared with an isotropic plasma at the same temperature.",1311.5513v3
+2013-11-25,Anomalous Viscosity of the Quark-Gluon Plasma,"The shear viscosity of the quark-gluon plasma is predicted to be lower than
+the collisional viscosity for weak coupling. The estimated ratio of the shear
+viscosity to entropy density is rather close to the ratio calculated by N = 4
+super Yang-Mills theory for strong coupling, which indicates that the
+quark-gluon plasma might be strongly coupled. However, in presence of momentum
+anisotropy, the Weibel instability can arise and drive the turbulent transport.
+Shear viscosity can be lowered by enhanced collisionality due to turbulence,
+but the decorrelation time and its relation to underlying dynamics and
+color-magnetic fields have not been calculated self-consistently. In this
+paper, we use resonance broadening theory for strong turbulence to calculate
+the anomalous viscosity of the quark-gluon plasma for nonequilibrium. For
+saturated Weibel instability, we estimate the scalings of the decorrelation
+rate and viscosity and compare these with collisional transport. This
+calculation yields an explicit connection between the underlying momentum space
+anisotropy and the viscosity anomaly.",1311.6347v2
+2013-11-26,Specific features of band structure and optical anisotropy of Cu2CdGeSe4 quaternary compounds,"The complex theoretical and experimental studies of the band structure and
+the optical functions of the Cu2CdGeSe4 quaternary crystals are reported. The
+benchmark band structure calculations were performed using the first-principles
+methods. As a result, the structural, electronic, optical and elastic
+properties of Cu2CdGeSe4 were calculated in the general gradient approximation
+(GGA) and local density approximation (LDA). The calculated dielectric function
+and optical absorption spectra exhibit some anisotropic behavior. Detailed
+analysis of the band energy dispersion and the effective space charge density
+helped in establishing the origin of the band structure anisotropy. All
+calculated properties are compared with the experimental data. An additional
+comparison with a similar crystal of Cu2CdGeSe4 allowed to reveal the role
+played by the anions (S or Se) in formation of the optical properties of these
+two materials.",1311.6753v1
+2013-11-27,Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model,"The LHC data on azimuthal anisotropy harmonics from PbPb collisions at
+center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in
+the framework of the HYDJET++ model. The cross-talk of elliptic $v_2$ and
+triangular $v_3$ flow in the model generates both even and odd harmonics of
+higher order. Comparison with the experimental data shows that this mechanism
+is able to reproduce the $p_{\rm T}$ and centrality dependencies of
+quadrangular flow $v_4$, and also the basic trends for pentagonal $v_5$ and
+hexagonal $v_6$ flows.",1311.7054v2
+2013-11-30,Expansion of a Bose-Einstein Condensate with Vortices,"The expansion of Bose-Einstein condensates (BECs) is numerically studied.
+Usually, the aspect ratio of a condensate is inverted due to the anisotropy of
+the uncertainty principle. In turbulent BECs, however, the aspect ratio remains
+constant. The reason for this phenomenon is still unknown, being a challenging
+topic in the study of quantum turbulence. Here, the two-dimensional
+Gross-Pitaevskii equation is solved and the time development of the aspect
+ratio and of the radii of the condensates are calculated in the presence of
+vortices. The results indicate that vortex pairs must be added to a condensate
+in order to expand it while maintaining its aspect ratio. The anisotropy due to
+the vortex pairs competes with that due to the uncertainty principle so that
+the aspect ratio remains constant.",1312.0093v1
+2013-12-02,Thermodynamic properties of LiCu$_{2}$O$_{2}$ multiferroic compound,"A spin model of quasi-one dimensional LiCu$_{2}$O$_{2}$ compound with ground
+state of ellipsoidal helical structure in which the helical axis is along the
+diagonal of CuO$_{4}$ squares has been adopted. By taking into account the
+interchain coupling and exchange anisotropy, the exotic magnetic properties and
+ferroelectricity induced by spiral spin order have been studied by performing
+Monte Carlo simulation. The simulation results qualitatively reproduce the main
+characters of ferroelectric and magnetic behaviors of LiCu$_{2}$O$_{2}$
+compound and confirm the low-temperature incollinear spiral ordering.
+Furthermore, by performing the calculations of spin structure factor, we
+systematically investigate the effects of different exchange coupling on the
+lower-temperature magnetic transition, and find that the spiral spin order
+depends not only on the ratio of nearest and next-nearest neighbor inchain spin
+coupling but also strongly on the exchange anisotropy.",1312.0293v1
+2013-12-02,Numerical studies of Minimally Doubled Fermions,"We have performed the first numerical study of minimally doubled fermions of
+the Karsten-Wilczek class in the quenched approximation. This requires fixing
+the counterterms, which arise due to hypercubic symmetry breaking induced by
+the Karsten-Wilczek term. Non-perturbative renormalisation criteria are
+formulated after a detailed study of the parameter dependence of mesonic
+observables. Minimisation of the mass anisotropy of the pseudoscalar ground
+state fixes non-perturbative renormalisation conditions for the counterterm
+coefficients. These anisotropies are mapped out by probing different euclidean
+components of the transfer matrix through calculations of the pseudoscalar
+ground state mass in different directions. The chiral behaviour of the
+pseudoscalar ground state is studied with the tuned Karsten-Wilczek action for
+multiple lattice spacings. Light pseudoscalar masses ($ M_{PS} \lesssim
+250\,MeV $) were achieved in the quenched approximation without encountering
+exceptional configurations. The presence of quenched chiral logarithms is
+studied under the tentative assumption of Goldstone Boson-like behaviour.",1312.0488v2
+2013-12-05,Diffusive motion of particles and dimers over anisotropic lattices,"Behavior of the mixture of particles and dimers moving with different jump
+rates at reconstructed surfaces is described. Collective diffusion coefficient
+is calculated by the variational approach. Anisotropy of the collective
+particle motion is analyzed as a function of jump rates and local particle
+density. Analytic expressions are compared with the results of Monte Carlo
+simulations of diffusing particle and dimer mixture. Direction of driven
+diffusive motion of the same system depends on the jump anisotropy and on the
+value of driving force. Driven motion results in the particle and dimer
+separation when the directions of their easy diffusion axes differ. It is shown
+that in such case trapping sites concentrated at some surface areas act as
+filters or barriers for particle and dimer mixtures.",1312.1592v2
+2013-12-10,Spectrum splitting of bimagnon excitations in a spatially frustrated Heisenberg antiferromagnet revealed by resonant inelastic x-ray scattering,"We perform a comprehensive analysis of the bimagnon resonant inelastic x-ray
+scattering (RIXS) intensity spectra of the spatially frustrated Jx-Jy-J2
+Heisenberg model on a square lattice in both the antiferromagnetic and the
+collinear antiferromagnetic phase. We study the model for strong frustration
+and significant spatial anisotropy to highlight the key signatures of RIXS
+spectrum splitting which may be experimentally discernible. Based on an
+interacting spin wave theory study within the ladder approximation
+Bethe-Salpeter scheme, we find the appearance of a robust two-peak structure
+over a wide range of the transferred momenta in both magnetically ordered
+phases. The unfrustrated model has a single-peak structure with a two-peak
+splitting originating due to spatial anisotropy and frustrated interactions.
+Our predicted two-peak structure from both magnetically ordered regime can be
+realized in iron pnictides.",1312.2876v2
+2013-12-12,Influence of the structure defects on the magnetic properties of the FePt/Fe bilayer,"Thin magnetic multilayered films containing FePt have attracted a lot of
+attention recently due to their possible usage in ultra-high density magnetic
+storage. Although structure defects play a dramatic role in the magnetization
+process and influence magnetic properties in general this dependence haven't
+been studied thoroughly. The main aim of this work was to perform theoretical
+investigation of the magnetic properties of FePt and Fe/FePt thin films with
+high coercivity with respect to the structure defects such as anisotropy
+constant, magnetization saturation, exchange constant fluctuations and easy
+axis deviation. For selected defect patterns the coercive field dependence on
+layer thicknesses was analysed. Numerical study of the bilayer with hard
+magnetic layer having the planar anisotropy was carried on using micromagnetic
+calculations. Values of layers thickness have been found optimal for
+perspective applications, the dependence of the hysteresis loop shape upon the
+magnetization process has been shown and analysed.",1312.3541v1
+2013-12-16,"Competing orders, competing anisotropies, and multicriticality: The case of Co-doped YbRh2Si2","Motivated by the unusual evolution of magnetic phases in stoichiometric and
+Co-doped YbRh2Si2, we study Heisenberg models with competing ferromagnetic and
+antiferromagnetic ordering combined with competing anisotropies in exchange
+interactions and g factors. Utilizing large-scale classical Monte-Carlo
+simulations, we analyze the ingredients required to obtain the characteristic
+crossing point of uniform susceptibilities observed experimentally near the
+ferromagnetic ordering of Yb(Rh0.73Co0.27)2Si2. The models possess
+multicritical points, which we speculate to be relevant for the behavior of
+clean as well as doped YbRh2Si2. We also make contact with experimental data on
+YbNi4P2 where a similar susceptibility crossing has been observed.",1312.4539v1
+2013-12-17,Reversal time of the magnetization of magnetic nanoparticles at very low damping,"The magnetization reversal time of ferromagnetic nanoparticles is
+investigated in the very low damping regime. The energy-controlled diffusion
+equation rooted in a generalization of the Kramers escape rate theory for point
+Brownian particles in a potential to the magnetic relaxation of a macrospin,
+yields the reversal time in closed integral form. The latter is calculated for
+a nanomagnet with uniaxial anisotropy with a uniform field applied at an angle
+to the easy axis and for a nanomagnet with biaxial anisotropy with the field
+along the easy axis. The results completely agree with those yielded by
+independent numerical and asymptotic methods.",1312.4904v3
+2013-12-19,Secondary CMB anisotropies from bulk motions in the presence of stochastic magnetic fields,"Bulk motions of electrons along the line of sight induce secondary
+temperature fluctuations in the post-decoupling, reionized universe. In the
+presence of a magnetic field not only the scalar mode but also the vector mode
+act as a source for the bulk motion. The resulting angular power spectrum of
+temperature anisotropies of the cosmic microwave background is calculated
+assuming a simple model of reionization.Contributions from the standard
+adiabatic, curvature mode and a non helical magnetic field are included. The
+contribution due to magnetic fields with field strengths of order nG and
+negative magnetic spectral indices becomes important for multipoles larger than
+$\ell \sim 10^4$.",1312.5630v2
+2013-12-22,Dynamical Skyrmion State in a Spin Current Nano-Oscillator with Perpendicular Magnetic Anisotropy,"We study the spectral characteristics of spin current nano-oscillators based
+on the Pt/[Co/Ni] magnetic multilayer with perpendicular magnetic anisotropy.
+By varying the applied magnetic field and current, both localized and
+propagating spin wave modes of the oscillation are achieved. At small fields,
+we observe an abrupt onset of the modulation sidebands. We use micromagnetic
+simulations to identify this state as a dynamical magnetic skyrmion stabilized
+in the active device region by spin current injection, whose current-induced
+dynamics is accompanied by the gyrotropic motion of the core due to the skew
+deflection. Our results demonstrate a practical route for controllable skyrmion
+manipulation by spin current in magnetic thin films.",1312.6343v2
+2013-12-23,Projection method and new formulation of leading-order anisotropic hydrodynamics,"The introduced earlier projection method for boost-invariant and
+cylindrically symmetric systems is used to introduce a new formulation of
+anisotropic hydrodynamics that allows for three substantially different values
+of pressure acting locally in three different directions. Our considerations
+are based on the Boltzmann kinetic equation with the collision term treated in
+the relaxation time approximation and the momentum anisotropy is included
+explicitly in the leading term of the distribution function. A novel feature of
+our work is the complete analysis of the second moment of the Boltzmann
+equation, in addition to the zeroth and first moments that have been analyzed
+in earlier studies. We define the final equations of anisotropic hydrodynamics
+in the leading order as a subset of the analyzed moment equations (and their
+linear combinations) which agree with the Israel-Stewart theory in the case of
+small pressure anisotropies.",1312.6614v1
+2013-12-23,Effects of Electromagnetic Field on The Collapse and Expansion of Anisotropic Gravitating Source,"This paper is devoted to study the effects of electromagnetic on the collapse
+and expansion of anisotropic gravitating source. For this purpose, we have
+evaluated the generating solutions of Einstein-Maxwell field equations with
+spherically symmetric anisotropic gravitating source. We found that a single
+function generates the various anisotropic solutions. In this case every
+generating function involves an arbitrary function of time which can be chosen
+to fit several astrophysical time profiles. Two physical phenomenon occur, one
+is gravitational collapse and other is the cosmological expanding solution. In
+both cases electromagnetic field effects the anisotropy of the model. For
+collapse the anisotropy is increased while for expansion it deceases from
+maximum value to finite positive value. In case of collaps there exits two
+horizons like in case of Reissner-Nordstr$\ddot{o}$m metric.",1312.6898v2
+2014-01-01,Valleytronics on the Surface of Topological Crystalline Insulator: Elliptic Dichroism and Valley-Selective Optical Pumping,"The low-energy theory of the surface of the topological crystalline insulator
+(TCI) is characterized by four Dirac cones anisotropic into the $x$ and $y$
+directions. Recent experiments have shown that the band gap can be introduced
+in these Dirac cones by crystal distortion by applying strain to the crystal
+structure. The TCI surface provides us with a new way to valleytronics when
+gaps are given to Dirac cones. Indeed the system has the Chern number and three
+valley-Chern numbers. We investigate the optical absorption on the TCI surface.
+It shows a strong elliptic dichroism though the four Dirac cones have the same
+chiralities. Namely, it is found that the absorptions of the right- and
+left-polarized light are different, depending on the sign of mass and the
+location of the Dirac cones, owing to the anisotropy of the Dirac cone. By
+measuring this elliptic dichroism it is possible to determine the anisotropy of
+a Dirac cone experimentally.",1401.0273v2
+2014-01-16,Absence of quasiclassical coherence in mean-field dynamics of bosons in a kinetically frustrated regime,"We study numerically the dynamics of bosons on a triangular lattice after
+quenching both the on-site interactions and the external trapping potential to
+negative values. In a similar situation on the square lattice, the dynamics can
+be understood in terms of an effectively reversed Hamiltonian. On the
+triangular lattice, however, the kinetic part of the reversed Hamiltonian is
+frustrated and whether coherence can develop is an open question. The strength
+of the frustration can be changed by tuning the ratio of the hopping rates
+along different directions. We calculate time-of-flight images at different
+times after the quench for different values of the hopping anisotropy. We
+observe peaks at the maxima of the original non-interacting dispersion relation
+both in the isotropic case and also in the rhombic limit of high hopping
+anisotropy. For an intermediate value, however, no coherence develops up to the
+longest simulation times. These results imply that experiments along similar
+lines could study unconventional superfluidity of bosons and aspects of the
+conjectured spin-liquid behavior in the hard-core limit.",1401.3966v2
+2014-01-18,Enhancement of Perpendicular Magnetic Anisotropy and Transmission of Spin-Hall-Effect-Induced Spin Currents by a Hf Spacer Layer in W/Hf/CoFeB/MgO Layer,"We report that strong perpendicular magnetic anisotropy of the ferromagnetic
+layer in a W/CoFeB/MgO multilayer structure can be established by inserting a
+Hf layer as thin as 0.25 nm between the W and CoFeB layers. The Hf spacer also
+allows transmission of spin currents generated by an in-plane charge current in
+the W layer to apply strong spin torque on the CoFeB, thereby enabling
+current-driven magnetic switching. The antidamping-like and field-like
+components of the spin torque exerted on a 1 nm CoFeB layer are of comparable
+magnitudes in this geometry. Both components originate from the spin Hall
+effect in the underlying W layer.",1401.4617v1
+2014-01-28,Phenomenological phase diagram of superfluid 3He in a stretched aerogel,"Highly anisotropic ""nematically ordered"" aerogel induces global uniaxial
+anisotropy in superfluid 3He. The anisotropy lowers symmetry of 3He in aerogel
+from spherical to axial. As a result instead of one transition temperature in
+the state, characterized by the orbital moment l=1 there are two, corresponding
+to projections l_z=o and l_z=\pm 1. The splitting of transition has a
+pronounced effect on the phase diagram of superfluid 3He and on a structures of
+appearing phases. Possible phase diagrams, obtained phenomenologically on a
+basis of Landau expansion of thermodynamic potential in a vicinity of the
+transition temperature are presented here. The order parameters, corresponding
+to each phase and their temperature dependencies are found.",1401.7297v2
+2014-01-31,Firehose and Mirror Instabilities in a Collisionless Shearing Plasma,"Hybrid-kinetic numerical simulations of firehose and mirror instabilities in
+a collisionless plasma are performed in which pressure anisotropy is driven as
+the magnetic field is changed by a persistent linear shear $S$. For a
+decreasing field, it is found that mostly oblique firehose fluctuations grow at
+ion Larmor scales and saturate with energies $\sim$$S^{1/2}$; the pressure
+anisotropy is pinned at the stability threshold by particle scattering off
+microscale fluctuations. In contrast, nonlinear mirror fluctuations are large
+compared to the ion Larmor scale and grow secularly in time; marginality is
+maintained by an increasing population of resonant particles trapped in
+magnetic mirrors. After one shear time, saturated order-unity magnetic mirrors
+are formed and particles scatter off their sharp edges. Both instabilities
+drive sub-ion-Larmor--scale fluctuations, which appear to be
+kinetic-Alfv\'{e}n-wave turbulence. Our results impact theories of momentum and
+heat transport in astrophysical and space plasmas, in which the stretching of a
+magnetic field by shear is a generic process.",1402.0010v2
+2014-02-10,A search for small and medium scale anisotropy of cosmic rays above 1 PeV registered at the Tunka-133 array,"A search for anisotropy at different scales in the arrival directions of
+cosmic rays with energies above 1 PeV is performed with data of the Tunka-133
+array. A number of regions with angular sizes up to approximately 30 degrees
+that deviate from the uniform background with a statistical significance
+greater than three standard deviations are found using the shuffling technique
+both in the complete data set and its subsets in different energy ranges. Some
+regions with an excess of cosmic rays correlate with the distribution of
+possible cosmic ray sources. A comparison of the results with a similar
+analysis of the legacy data of the EAS MSU array is presented.",1402.2075v2
+2014-02-10,Magnetic edge anisotropy in graphene-like honeycomb crystals,"The independent predictions of edge ferromagnetism and the Quantum Spin Hall
+phase in graphene have inspired the quest of other two dimensional honeycomb
+systems, such as silicene, germanene, stanene, iridiates, and organometallic
+lattices, as well as artificial superlattices, all of them with electronic
+properties analogous to those of graphene, but much larger spin orbit coupling.
+Here we study the interplay of ferromagnetic order and spin orbit interactions
+at the zigzag edges of these graphene-like systems. We find an in-plane
+magnetic anisotropy that opens a gap in the otherwise conducting edge channels,
+that should result in large changes of electronic properties upon rotation of
+the magnetization.",1402.2235v2
+2014-02-17,A case study of spin-$1$ Heisenberg model in a triangular lattice,"We study the spin-$1$ model in a triangular lattice in presence of a uniaxial
+anisotropy field using a Cluster Mean-Field approach (CMF). The interplay
+between antiferromagnetic exchange, lattice geometry and anisotropy forces
+Gutzwiller mean-field approaches to fail in a certain region of the phase
+diagram. There, the CMF yields two supersolid (SS) phases compatible with those
+present in the spin-$1/2$ XXZ model onto which the spin-$1$ system maps.
+Between these two SS phases, the three-sublattice order is broken and the
+results of the CMF depend heavily on the geometry and size of the cluster. We
+discuss the possible presence of a spin liquid in this region.",1402.4008v2
+2014-02-18,Switching Properties in Magnetic Tunnel Junctions with Interfacial Perpendicular Anisotropy: Micromagnetic Study,"The role of universal memory can be successfully satisfied by magnetic tunnel
+junctions (MTJs) where the writing mechanism is based on spin-transfer torque
+(STT). An improvement in the switching properties (lower switching current
+density maintaining the thermal stability) has been achieved in MTJs with
+interfacial perpendicular anisotropy (IPA) at the interface between CoFeB and
+MgO. In this paper, micromagnetic simulations point out the influence of IPA
+and saturation magnetization (MS) on the properties of fast magnetization
+reversal achieved in 5, 10 and 20 ns. Both cases of in-plane and out-of-plane
+free layer are considered. In addition, the thermal effect is included for the
+in-plane switching at 20 ns and a complete analysis of energy dissipation
+during the switching is illustrated. This study can provide useful information
+for the design of STT-based memories.",1402.4352v1
+2014-02-23,Solution to the Inverse Wulff Problem by Means of the Enhanced Semidefinite Relaxation Method,"We propose a novel method of resolving the optimal anisotropy function. The
+idea is to construct the optimal anisotropy function as a solution to the
+inverse Wulff problem, i.e. as a minimizer for the anisoperimetric ratio for a
+given Jordan curve in the plane. It leads to a nonconvex quadratic optimization
+problem with linear matrix inequalities. In order to solve it we propose the
+so-called enhanced semidefinite relaxation method which is based on a solution
+to a convex semidefinite problem obtained by a semidefinite relaxation of the
+original problem augmented by quadratic-linear constraints. We show that the
+sequence of finite dimensional approximations of the optimal anisoperimetric
+ratio converges to the optimal anisoperimetric ratio which is a solution to the
+inverse Wulff problem. Several computational examples, including those
+corresponding to boundaries of real snowflakes and discussion on the rate of
+convergence of numerical method are also presented in this paper.",1402.5668v2
+2014-02-28,Probing anisotropy in a new noncentrosymmetric superconductor BiPd,"Strength of Rashba type antisymmetric spin orbit coupling has the crucial
+effect on superconducting and normal state properties in noncentrosymmetric
+(NCS) superconductors. This can be seen on various anisotropic properties of
+the system. For a system with lowered crystalline symmetry as in
+noncentrosymmetric crystals, the superconducting pairing state can have
+correlation to the normal state properties. In our earlier work we have shown
+that alfa-BiPd which has a monoclinic (P_21) structure with the absence of the
+centre of inversion exhibits bulk superconductivity at 3.8 K. In order to
+understand the role of spin-orbit scattering, we have studied the anisotropic
+properties of high quality single crystal (RRR 170) of NCS BiPd by measuring
+magnetic susceptibility, electrical transport from 1.8 K to 300 K and
+isothermal M_H loop (1.8 K to 3.8 K) in the superconducting state for <010> and
+<100> crystallographic directions respectively. Moderate anisotropy up to 30 %
+has been found in the electrical transport possibly indicating significant
+Rashba type antisymmetric spin orbit coupling present in alfa-BiPd.",1402.7232v1
+2014-03-16,Anisotropic intrinsic spin Hall effect in quantum wires,"We use numerical simulations to investigate the spin Hall effect in quantum
+wires in the presence of both Rashba and Dresselhaus spin-orbit coupling. We
+find that the intrinsic spin Hall effect is highly anisotropic with respect to
+the orientation of the wire, and that the nature of this anisotropy depends
+strongly on the electron density and the relative strengths of the Rashba and
+Dresselhaus spin-orbit coupling. In particular, at low densities when only one
+subband of the quantum wire is occupied, the spin Hall effect is strongest for
+electron momentum along the $[\bar{1}10]$ axis, which is opposite than what is
+expected for the purely 2D case. In addition, when more than one subband is
+occupied, the strength and anisotropy of the spin Hall effect can vary greatly
+over relatively small changes in electron density, which makes it difficult to
+predict which wire orientation will maximize the strength of the spin Hall
+effect. These results help to illuminate the role of quantum confinement in
+spin-orbit-coupled systems, and can serve as a guide for future experimental
+work on the use of quantum wires for spin-Hall-based spintronic applications.",1403.3936v1
+2014-03-19,Is the anisotropy of the upper critical field of Sr$_2$RuO$_4$ consistent with a helical $p$-wave state?,"We calculate the angular and temperature $T$ dependencies of the upper
+critical field $H_{c2}(\theta,\phi,T)$ for the $C_{4v}$ point group helical
+$p$-wave states, assuming a single uniaxial ellipsoidal Fermi surface, Pauli
+limiting, and strong spin-orbit coupling that locks the spin-triplet $\vec{\bf
+d}$-vectors onto the layers. Good fits to the Sr$_2$RuO$_4$
+$H_{c2,a}(\theta,T)$ data of Kittaka {\it et al.} [Phys. Rev. B {\bf 80},
+174514 (2009)] are obtained. Helical states with $\vec{\bf d}(\vec{\bf
+k})=k_x\vec{\bf x}-k_y\vec{\bf y}$ and $k_y\vec{\bf x}+k_x\vec{\bf y}$ (or
+$k_x\vec{\bf x}+k_y\vec{\bf y}$ and $k_y\vec{\bf x}-k_x\vec{\bf y}$) produce
+$H_{c2}(90^{\circ},\phi,T)$ that greatly exceed (or do not exhibit) the
+four-fold azimuthal anisotropy magnitudes observed in Sr$_2$RuO$_4$ by Kittaka
+{\it et al.} and by Mao {\it et al.} [Phys. Rev. Lett. {\bf 84}, 991 (2000)],
+respectively.",1403.4715v1
+2014-03-20,Spin susceptibility of two-dimensional transition metal dichalcogenides,"We have obtained analytical expressions for the q-dependent static spin
+susceptibility of monolayer transition metal dichalcogenides, considering both
+the electron-doped and hole-doped cases. Our results are applied to calculate
+spin-related physical observables of monolayer MoS2, focusing especially on
+in-plane/out-of-plane anisotropies. We find that the hole-mediated RKKY
+exchange interaction for in-plane impurity-spin components decays with the
+power law $R^{-5/2}$ as a function of distance $R$, which deviates from the
+$R^{-2}$ power law normally exhibited by a two-dimensional Fermi liquid. In
+contrast, the out-of-plane spin response shows the familiar $R^{-2}$ long-range
+behavior. We also use the spin susceptibility to define a collective g-factor
+for hole-doped MoS2 systems and discuss its density-dependent anisotropy.",1403.5021v3
+2014-03-21,"Timescales, dynamical phase transitions and 3rd order phase transitions in the 1d anisotropic XY model","Recent research into time-integrated observables has revealed a special class
+of states which cap- ture the singular features of the generating functions of
+those observables, as estimated by full counting statistics (FCS). In this work
+we extend the results of [Phys. Rev. B 87 184303 (2013)] to the 1d anisotropic
+XY -model and find a set of FCS critical points associated with the
+time-integrated transverse magnetization and anisotropy. We show dynamical
+phase transitions (DPTs) as defined in [Phys. Rev. Lett. 110 135704 (2013)] do
+not emerge on quenching the states associated with the time-integrated
+anisotropy across FCS critical points. We also study the timescales required to
+prepare the associated special states of the transverse magnetization using
+appropriate Markovian baths and find they are independent of the number of
+spins in the chain. However the probability to evolve to such a state decreases
+drastically with increasing system size due to dissipation. Thus when preparing
+such states it is preferable to use few body systems and to reach the
+thermodynamic limit it is necessary to use an ancillary system in conjunction
+with the Markovian baths.",1403.5515v1
+2014-03-28,"The Glasma, Photons and the Implications of Anisotropy","We introduce distribution functions for quarks and gluons in the Glasma and
+discuss how they satisfy various relationships of statistical physics. We use
+these distributions to compute photon production in the early stages of heavy
+ion collisions. Photon rates satisfy geometric scaling, that is, the emission
+rate per unit area scales as a function of the saturation momenta divided by
+the transverse momentum of the photon. Photon distributions from the Glasma are
+steeper than those computed in the Thermalized Quark Gluon Plasma (TQGP). Both
+the delayed equilibration of the Glasma and a possible anisotropy in the
+pressure lead to slower expansion and mean times of photon emission of fixed
+energy are increased. This delayed emission might allow for larger photon
+elliptic flow.",1403.7462v1
+2014-04-03,On the incorporation of cubic and hexagonal interfacial energy anisotropy in phase field models using higher order tensor terms,"In this paper, we show how to incorporate cubic and hexagonal anisotropies in
+interfacial energies in phase field models; this incorporation is achieved by
+including upto sixth rank tensor terms in the free energy expansion, assuming
+that the free energy is only a function of coarse grained composition, its
+gradient, curvature and aberration. We derive the number of non-zero and
+independent components of these tensors. Further, by demanding that the
+resultant interfacial energy is positive definite for inclusion of each of the
+tensor terms individually, we identify the constraints imposed on the
+independent components of these tensors. The existing results in the invariant
+group theory literature can be used to simplify the process of construction of
+some (but not all) of the higher order tensors. Finally, we derive the relevant
+phase field evolution equations.",1404.0757v2
+2014-04-03,Phases of triangular lattice antiferromagnet near saturation,"We consider 2D Heisenberg antiferromagnets on a triangular lattice with
+spatially anisotropic interactions in a high magnetic field close to the
+saturation. We show that this system possess rich phase diagram in
+field/anisotropy plane due to competition between classical and quantum orders:
+an incommensurate non-coplanar spiral state, which is favored classically, and
+a commensurate co-planar state, which is stabilized by quantum fluctuations. We
+show that the transformation between these two states is highly non-trivial and
+involves two intermediate phases -- the phase with co-planar incommensurate
+spin order and the one with non-coplanar double-${\bf Q}$ spiral order. The
+transition between the two co-planar states is of commensurate- incommensurate
+type, not accompanied by softening of spin-wave excitations. We show that a
+different sequence of transitions holds in triangular antiferromagnets with
+exchange anisotropy, such as Ba3CoSb2O9.",1404.1046v1
+2014-04-04,Cosmological signatures of brane inflation,"Cosmology motivated by string theory has been studied extensively in the
+recent literature. String theory is promising because it has interesting
+features such as unifying gravity, electromagnetic, weak and strong nuclear
+forces. However, even the energy scale of the experiments at the Large Hadron
+Collider (~TeV) is too low to detect any strong evidence for string theory. The
+energy scale of inflation can be above ~10^9 TeV. Therefore, it is expected to
+find some signature of string theory in cosmology.
+  String theory predicts ten space-time dimensions. In the brane world
+scenario, our four dimensional Universe is confined onto the higher dimensional
+object called the Brane in the ten dimensional space time. The
+Dirac-Born-Infeld (DBI) inflation is based on this idea. DBI inflation predicts
+a characteristic statistical feature in the Cosmic Microwave Background (CMB)
+temperature anisotropies. In this thesis, we study the predictions of the DBI
+inflation models on the CMB temperature anisotropies.",1404.1174v1
+2014-04-07,Crystal structure and physical properties of EuPtIn$_{4}$ intermetallic antiferromagnet,"We report the synthesis of EuPtIn$_{4}$ single crystalline platelets by the
+In-flux technique. This compound crystallizes in the orthorhombic Cmcm
+structure with lattice parameters $a=4.542(1)$ \AA, $b=16.955(2)$ \AA$\,$ and
+$c=7.389(1)$ \AA. Measurements of magnetic susceptibility, heat capacity,
+electrical resistivity, and electron spin resonance (ESR) reveal that
+EuPtIn$_{4}$ is a metallic Curie-Weiss paramagnet at high temperatures and
+presents antiferromagnetic (AFM) ordering below $T_{N}=13.3$ K. In addition, we
+observe a successive anomaly at $T^{*} = 12.6$ K and a spin-flop transition at
+$H_{c} \sim 2.5$ T applied along the $ac$-plane. In the paramagnetic state, a
+single Eu$^{2+}$ Dysonian ESR line with a Korringa relaxation rate of $b =
+4.1(2)$ Oe/K is observed. Interestingly, even at high temperatures, both ESR
+linewidth and electrical resistivity reveal a similar anisotropy. We discuss a
+possible common microscopic origin for the observed anisotropy in these
+physical quantities likely associated with an anisotropic magnetic interaction
+between Eu$^{2+}$ 4$f$ electrons mediated by conduction electrons.",1404.1660v1
+2014-04-10,Magnetic response of holographic Lifshitz superconductors:Vortex and Droplet solutions,"In this paper a holographic model of $s$-wave superconductor with anisotropic
+Lifshitz scaling has been considered. In the presence of an external magnetic
+field our holographic model exhibits both vortex and droplet solutions. Based
+on analytic methods we have shown that the anisotropy has no effect on the
+vortex and droplet solutions whereas it may affect the condensation. Our vortex
+solution closely resembles the Ginzburg-Landau theory and a relation between
+the upper critical magnetic field and superconducting coherence length has been
+speculated from this comparison. Using Sturm-Liouville method, the effect of
+anisotropy on the critical parameters in insulator/superconductor phase
+transitions has been analyzed.",1404.2774v2
+2014-04-11,Effective S=1/2 description of the S=1 chain with strong easy plane anisotropy,"We present a study of the one-dimensional S=1 antiferromagnetic spin chain
+with large easy plane anisotropy, with special emphasis on field-induced
+quantum phase transitions. Temperature and magnetic field dependence of
+magnetization, specific heat, and thermal conductivity is presented using a
+combination of numerical methods. In addition, the original S=1 model is mapped
+into the low-energy effective S=1/2 XXZ Heisenberg chain, a model which is
+exactly solvable using the Bethe ansatz technique. The effectiveness of the
+mapping is explored, and we show that all considered quantities are in
+qualitative, and in some cases quantitative, agreement. The thermal
+conductivity of the considered S=1 model is found to be strongly influenced by
+the underlying effective description. Furthermore, we elucidate the low-lying
+electron spin resonance spectrum, based on a semi--analytical Bethe ansatz
+calculation of the effective S=1/2 model.",1404.3064v2
+2014-04-11,The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy,"Quasar luminosity functions are a fundamental probe of the growth and
+evolution of supermassive black holes. Measuring the intrinsic luminosity
+function is difficult in practice, due to a multitude of observational and
+systematic effects. As sample sizes increase and measurement errors drop,
+characterizing the systematic effects is becoming more important. It is well
+known that the continuum emission from the accretion disk of quasars is
+anisotropic --- in part due to its disk-like structure --- but current
+luminosity function calculations effectively assume isotropy over the range of
+unobscured lines of sight. Here, we provide the first steps in characterizing
+the effect of random quasar orientations and simple models of anisotropy on
+observed luminosity functions. We find that the effect of orientation is not
+insignificant and exceeds other potential corrections such as those from
+gravitational lensing of foreground structures. We argue that current
+observational constraints may overestimate the intrinsic luminosity function by
+as much as a factor of ~2 on the bright end. This has implications for models
+of quasars and their role in the Universe, such as quasars' contribution to
+cosmological backgrounds.",1404.3151v1
+2014-04-13,Temporal and Spatial Turbulent Spectra of MHD Plasma and an Observation of Variance Anisotropy,"The nature of MHD turbulence is analyzed through both temporal and spatial
+magnetic fluctuation spectra. A magnetically turbulent plasma is produced in
+the MHD wind-tunnel configuration of the Swarthmore Spheromak Experiment (SSX).
+The power of magnetic fluctuations is projected into directions perpendicular
+and parallel to a local mean field; the ratio of these quantities shows the
+presence of variance anisotropy which varies as a function of frequency.
+Comparison amongst magnetic, velocity, and density spectra are also made,
+demonstrating that the energy of the turbulence observed is primarily seeded by
+magnetic fields created during plasma production. Direct spatial spectra are
+constructed using multi-channel diagnostics and are used to compare to
+frequency spectra converted to spatial scales using the Taylor Hypothesis.
+Evidence for the observation of dissipation due to ion inertial length scale
+physics is also discussed as well as the role laboratory experiment can play in
+understanding turbulence typically studied in space settings such as the solar
+wind. Finally, all turbulence results are shown to compare fairly well to a
+Hall-MHD simulation of the experiment.",1404.3336v1
+2014-04-14,The Hubble Expansion is Isotropic in the Epoch of Dark Energy,"The isotropy of the universal Hubble expansion is a fundamental tenet of
+physical cosmology, but it has not been precisely tested during the current
+epoch, when dark energy is dominant. Anisotropic expansion will produce a
+shearing velocity field, causing objects to stream toward directions of faster
+expansion and away from directions of slower expansion. This work tests the
+basic cosmological assumption of isotropic expansion and thus the isotropy of
+dark energy. The simplest anisotropy will manifest as a quadrupolar curl-free
+proper motion vector field. We derive this theoretical signature using a
+tri-axial expanding metric with a flat geometry (Bianchi I model), generalizing
+and correcting previous work. We then employ the best current data, the Titov &
+Lambert (2013) proper motion catalog of 429 objects, to measure the isotropy of
+universal expansion. We demonstrate that the Hubble expansion is isotropic to
+7% (1 $\sigma$), corresponding to streaming motions of 1 microarcsecond/yr, in
+the best-constrained directions (-19% and +17% in the least-constrained
+directions) and does not significantly deviate from isotropy in any direction.
+The Gaia mission, which is expected to obtain proper motions for 500,000
+quasars, will likely constrain the anisotropy below 1%.",1404.3735v1
+2014-04-14,Magnetic field modulated Kondo effect in a single-magnetic-ion molecule,"We study numerically the low-temperature electronic transport properties of a
+single-ion magnet with uniaxial and transverse spin anisotropies. We find clear
+signatures of a Kondo effect caused by the presence of a transverse
+(zero-field) anisotropy in the molecule. Upon applying a transverse magnetic
+field to the single-ion magnet, we observe oscillations of the Kondo effect due
+to the presence of diabolical (degeneracy) points of the energy spectrum of the
+molecule caused by a geometrical phase interference effects similar to those
+observed in the quantum tunneling of multi-ion molecular nanomagnets. The
+field-induced lifting of the ground state degeneracy competes with the
+interference modulation, resulting in some cases in a suppression of the Kondo
+peak.",1404.3755v2
+2014-04-15,Plasmons and screening in monolayer and multilayer black phosphorus,"Black phosphorus exhibits a high degree of band anisotropy. However, we found
+that its in-plane static screening remains relatively isotropic for momenta
+relevant to elastic long-range scattering processes. On the other hand, the
+collective electronic excitations in the system exhibit a strong anisotropy.
+Band non-parabolicity leads to a plasmon frequency which scales as $n^{\beta}$,
+where $n$ is the carrier concentration, and $\beta<\tfrac{1}{2}$. Screening and
+charge distribution in the out-of-plane direction are also studied using a
+non-linear Thomas-Fermi model.",1404.4035v2
+2014-04-18,Transport Properties of Dirac Ferromagnet,"We propose a model ferromagnet based on the Dirac Hamiltonian in three
+spatial dimensions, and study its transport properties which include
+anisotropic magnetoresistance (AMR) and anomalous Hall (AH) effect. This
+relativistic extension allows two kinds of ferromagnetic order parameters,
+denoted by $\bm{M}$ and $\bm{S}$, which are distinguished by the relative sign
+between the positive- and negative-energy states (at zero momentum) and become
+degenerate in the non-relativistic limit. Because of the relativistic coupling
+between the spin and the orbital motion, both $\bm{M}$ and $\bm{S}$ induce
+anisotropic deformations of the energy dispersion (and the Fermi surfaces) but
+in mutually opposite ways. The AMR is determined primarily by the anisotropy of
+the Fermi surface (group velocity), and secondarily by the anisotropy of the
+damping; the latter becomes important for ${\bm M}=\pm{\bm S}$, where the Fermi
+surfaces are isotropic. Even when the chemical potential lies in the gap, the
+AH conductivity is found to take a finite non-quantized value, $\sigma_{ij} =
+-(\alpha /3\pi^2 \hbar) \epsilon_{ijk} S_k $, where $\alpha$ is the (effective)
+fine structure constant. This offers an example of Hall insulator in three
+spatial dimensions.",1404.4741v2
+2014-04-23,Meson Life Time in the Anisotropic Quark-Gluon Plasma,"In the hot (an)isotropic plasma the meson life time $\tau$ is defined as a
+time scale after which the meson dissociates. According to the gauge/gravity
+duality, this time can be identified with the inverse of the imaginary part of
+the frequency of the quasinormal modes, $\omega_I$, in the (an)isotropic black
+hole background. In the high temperature limit, we numerically show that at
+fixed temperature(entropy density) the life time of the mesons
+decreases(increases) as the anisotropy parameter raises. For general case, at
+fixed temperature we introduce a polynomial function for $\omega_I$ and observe
+that the meson life time decreases. Moreover, we realize that $(s/T^3)^6$,
+where $s$ and $T$ are entropy density and temperature of the plasma
+respectively, can be expressed as a function of anisotropy parameter over
+temperature. Interestingly, this function is a Pad\'{e} approximant.",1404.5790v2
+2014-04-26,"Fe clusters (Fe$_n$, n=1-6) chemisorbed on vacancy defects in graphene: Stability, spin-dipole moment and magnetic anisotropy","In this work, we have studied the chemical and magnetic interactions of
+Fe$_n$ ; n=1-6 clusters with vacancy defects (monovacancy to correlated
+vacancies with six missing C atoms) in a graphene sheet by ab-initio density
+functional calculations combined with Hubbard U corrections for correlated Fe-
+d electrons. It is found that the vacancy formation energies are lowered in the
+presence of Fe, indicating an easier destruction of the graphene sheet. Due to
+strong chemical interactions between Fe clusters and vacancies, a complex
+distribution of magnetic moments appear on the distorted Fe clusters which
+results in reduced averaged magnetic moments compared to the free clusters. In
+addition to that, we have calculated spin-dipole moments and magnetic
+anisotropy energies. The calculated spin-dipole moments arising from
+anisotropic spin density distributions, vary between positive and negative
+values, yielding increased or decreased effective moments. Depending on the
+cluster geometry, the easy axis of magnetization of the Fe clusters shows
+in-plane or out-of-plane behavior.",1404.6641v2
+2014-04-27,Haldane-like antiferromagnetic spin chain in the large anisotropy limit,"We consider the one dimensional, periodic spin chain with $N$ sites, similar
+to the one studied by Haldane \cite{hal}, however in the opposite limit of very
+large anisotropy and small nearest neighbour, anti-ferromagnetic exchange
+coupling between the spins, which are of large magnitude $s$. For a chain with
+an even number of sites we show that actually the ground state is non
+degenerate and given by a superposition of the two N\'eel states, due to
+quantum spin tunnelling. With an odd number of sites, the N\'eel state must
+necessarily contain a soliton. The position of the soliton is arbitrary thus
+the ground state is $N$-fold degenerate. This set of states reorganizes into a
+band. We show that this occurs at order $2s$ in perturbation theory. The ground
+state is non-degenerate for integer spin, but degenerate for half-odd integer
+spin as is required by Kramer's theorem \cite{kram}.",1404.6706v1
+2014-04-28,Helical Inflation and Cosmic Strings,"Recent BICEP2 detection of low-multipole B-mode polarization anisotropy in
+the cosmic microwave background radiation supports the inflationary universe
+scenario and suggests a large inflaton field range. The latter feature can be
+achieved with axion fields in the framework of string theory. We present such a
+helical model which naturally becomes a model with a single cosine potential,
+and which in turn reduces to the (quadratic) chaotic inflation model in the
+super-Planckian limit. The slightly smaller tensor/scalar ratio $r$ of models
+of this type provides a signature of the periodic nature of an axion potential.
+We present a simple way to quantify this distinctive feature. As axions are
+intimately related to strings/vortices and strings are ubiquitous in string
+theory, we explore the possibility that cosmic strings may be contributing to
+the B-mode polarization anisotropy observed.",1404.6988v3
+2014-05-02,The Planck mission,"These lecture from the 100th Les Houches summer school on ""Post-planck
+cosmology"" of July 2013 discuss some aspects of the Planck mission, whose prime
+objective was a very accurate measurement of the temperature anisotropies of
+the Cosmic Microwave Background (CMB). We announced our findings a few months
+ago, on March 21$^{st}$, 2013. I describe some of the relevant steps we took to
+obtain these results, sketching the measurement process, how we processed the
+data to obtain full sky maps at 9 different frequencies, and how we extracted
+the CMB temperature anisotropies map and angular power spectrum. I conclude by
+describing some of the main cosmological implications of the statistical
+characteristics of the CMB we found. Of course, this is a very much shortened
+and somewhat biased view of the \Planck\ 2013 results, written with the hope
+that it may lead some of the students to consult the original papers.",1405.0439v1
+2014-05-07,Anisotropic relaxation dynamics in a dipolar Fermi gas driven out of equilibrium,"We report on the observation of a large anisotropy in the rethermalization
+dynamics of an ultracold dipolar Fermi gas driven out of equilibrium. Our
+system consists of an ultracold sample of strongly magnetic $^{167}$Er
+fermions, spin-polarized in the lowest Zeeman sublevel. In this system, elastic
+collisions arise purely from universal dipolar scattering. Based on
+cross-dimensional rethermalization experiments, we observe a strong anisotropy
+of the scattering, which manifests itself in a large angular dependence of the
+thermal relaxation dynamics. Our result is in very good agreement with recent
+theoretical predictions. Furthermore, we measure the rethermalization rate as a
+function of temperature for different angles and find that the suppression of
+collisions by Pauli blocking is not influenced by the dipole orientation.",1405.1537v2
+2014-05-05,The CMB Derivatives of Planck's Beam Asymmetry,"We investigate the anisotropy in cosmic microwave background Planck maps due
+to the coupling between its beam asymmetry and uneven scanning strategy.
+Introducing a pixel space estimator based on the temperature gradients, we find
+a highly significant (~20 \sigma) preference for these to point along ecliptic
+latitudes. We examine the scale dependence, morphology and foreground
+sensitivity of this anisotropy, as well as the capability of detailed Planck
+simulations to reproduce the effect, which is crucial for its removal, as we
+demonstrate in a search for the weak lensing signature of cosmic defects.",1405.1609v2
+2014-05-08,Electro-optic switching of dielectrically negative nematic through nanosecond electric modification of order parameter (NEMOP),"We present experimental studies of nanosecond electric modification of the
+order parameter (NEMOP) in a variety of nematic materials with negative
+dielectric anisotropy. The study demonstrates that NEMOP enables a large
+amplitude of fast (nanoseconds) electro-optic response with the field-induced
+birefringence on the order of 0.01 and a figure of merit (FoM) on the order of
+$10^4$ $\mu $m$^2/$s; the latter is orders of magnitude higher than the FoM of
+the Frederiks effect traditionally used in electro-optic nematic devices. The
+amplitude of the NEMOP response is generally stronger in nematics with larger
+dielectric anisotropy and with higher natural (field-free) birefringence.",1405.2118v2
+2014-05-14,"Dipole Polarizability of Alkali-Metal (Na, K, Rb) - Alkaline-Earth-Metal (Ca,Sr) Polar molecules - Prospects of Alignment","Electronic open-shell ground-state properties of selected alkali-metal (AM) -
+alkaline-earth-metal (AEM) polar molecules are investigated. We determine
+potential energy curves of the 2{\Sigma}+ ground state at the coupled-cluster
+singles and doubles with partial triples (CCSD(T)) level of electron
+correlation. Calculated spectroscopic constants for the isotopes (23Na, 39K,
+85Rb) - (40Ca, 88Sr) are compared with available theoretical and experimental
+results. The variation of the permanent dipole moment (PDM), average dipole
+polarizability, and polarizability anisotropy with internuclear distance is
+determined using finite-field perturbation theory at the CCSD(T) level. Owing
+to moderate PDM (KCa: 1.67 D, RbCa: 1.75 D, KSr: 1.27 D, RbSr: 1.41 D) and
+large polarizability anisotropy (KCa: 566 a.u., RbCa: 604 a.u., KSr: 574 a.u.,
+RbSr: 615 a.u.), KCa, RbCa, KSr, and RbSr are potential candidates for
+alignment and orientation in combined intense laser and external static
+electric fields.",1405.3503v1
+2014-05-15,Disentangling Soft and Hard Hadron Yields in PbPb Collisions at $\sqrt{s_{NN}}$ = 2.76 ATeV,"We demonstrate that charged pion spectra in central and peripheral PbPb
+collisions at $\sqrt{s}$ = 2.76 ATeV obtained via perturbative quantum
+chromodynamics improved parton model calculations [17] can be approximated by
+the Tsallis distribution for transverse momenta $p_T \geq$ 4 GeV/c. Then, we
+propose a model in which, hadrons produced in heavy-ion collisions stem either
+from ""soft"" or ""hard"" processes, and are distributed according to the Tsallis
+distribution in both types of yields. We describe transverse spectra as well as
+azimuthal anisotropy ($v_2$) of charged hadrons stemming from various
+centrality PbPb collisions at $\sqrt{s}$ = 2.76 ATeV [40,41,42] analytically.
+In addition, we find that the anisotropy decreases for more central collisions.",1405.3963v2
+2014-05-22,An Interacting Scenario for Dark Energy in Bianchi Type-I Universe,"We study the interaction between dark energy (DE) and dark matter (DM) in the
+scope of anisotropic bianchi type I space-time. First we derive the general
+form of the dark energy equation of state parameter (EoS) in both
+non-interacting and interacting cases and then we examine it's future by
+applying a hyperbolic scale factor. It is shown that in non-interacting case,
+depending on the value of the anisotropy parameter $K$, the dark energy EoS
+parameter is varying from phantom to quintessence whereas in interacting case
+EoS parameter vary in quintessence region. However, in both cases the dark
+energy EoS parameter $\omega^{de}$, ultimately (i. e at $z=-1$) tends to the
+cosmological constant ($\omega^{de}=-1$). Moreover, we fixed the cosmological
+bound on the anisotropy parameter $K$ by using the recent observational data of
+Hubble parameter.",1405.5714v1
+2014-05-27,Stability analysis of (a class of) anisotropic spacetimes,"We consider spherically symmetric spacetimes sourced by a fluid with pressure
+anisotropy in the radial direction. We use gauge-invariant perturbation theory
+to study the stability of this class of spacetimes under axial perturbations.
+We apply our results to three diverse examples. Two examples arise as endpoints
+of collapse of a ball of fluid --- one describes a well-behaved stellar
+interior and the other has a naked singularity. We prove the stability of the
+stellar interior both with respect to Dirichlet and quasinormal mode boundary
+conditions on the perturbation. Surprisingly, the naked singularity is also
+stable under axial perturbations. Lastly, we take the example of anisotropic
+cosmology to show that in this case, the relevant perturbations are those in
+which the direction of anisotropy is also perturbed.",1405.6821v2
+2014-05-27,Stability of Multinode Dirac Semimetals against Strong Long-Range Correlations,"We study the stability of Dirac semimetals with $N$ nodes in three spatial
+dimensions against strong $1/r$ Coulomb interactions. We particularly study the
+cases of $N=4$ and $N=16$, where the $N=4$ Dirac semimetal is described by the
+staggered fermions and the $N=16$ Dirac semimetal is described by the doubled
+lattice fermions. We take into account the $1/r$ long-range Coulomb
+interactions between the bulk electrons. Based on the U(1) lattice gauge
+theory, we analyze the system from the strong coupling limit. It is shown that
+the Dirac semimetals survive in the strong coupling limit when the out-of-plane
+Fermi velocity anisotropy of the Dirac cones is weak, whereas they change to
+Mott insulators when the anisotropy is strong. A Possible global phase diagram
+of correlated multinode Dirac semimetals is presented. Implications of our
+result to the stability of Weyl semimetals and three-dimensional topological
+insulators are discussed.",1405.6932v2
+2014-05-29,Reconfigurable anisotropy and functional transformations with VO$_{2}$-based metamaterial electric circuits,"We demonstrate an innovative multifunctional artificial material that
+combines exotic metamaterial properties and the environmentally responsive
+nature of phase change media. The tunable metamaterial is designed with the aid
+of two interwoven coordinate-transformation equations and implemented with a
+network of thin film resistors and vanadium dioxide ($VO_{2}$). The strong
+temperature dependence of $VO_{2}$ electrical conductivity results in a
+relevant modification of the resistor network behavior, and we provide
+experimental evidence for a reconfigurable metamaterial electric circuit (MMEC)
+that not only mimics a continuous medium but is also capable of responding to
+thermal stimulation through dynamic variation of its spatial anisotropy. Upon
+external temperature change the overall effective functionality of the material
+switches between a ""truncated-cloak"" and ""concentrator"" for electric currents.
+Possible applications may include adaptive matching resistor networks,
+multifunctional electronic devices, and equivalent artificial materials in the
+magnetic domain. Additionally, the proposed technology could also be relevant
+for thermal management of integrated circuits",1405.7743v1
+2014-06-11,Nonlinear valley and spin currents from Fermi pocket anisotropy in 2D crystals,"Controlled flow of spin and valley pseudospin is key to future electronics
+exploiting these internal degrees of freedom of carriers. Here we discover a
+universal possibility for generating spin and valley currents by electric bias
+or temperature gradient only, which arises from the anisotropy of Fermi pockets
+in crystalline solids. We find spin and valley currents to the second order in
+the electric field, as well as their thermoelectric counterparts, i.e. the
+nonlinear spin and valley Seebeck effects. These second-order nonlinear
+responses allow two unprecedented possibilities to generate pure spin and
+valley flows without net charge current: (i) by an AC bias; or (ii) by an
+arbitrary inhomogeneous temperature distribution. As examples, we predict
+appreciable nonlinear spin and valley currents in two-dimensional (2D) crystals
+including graphene, monolayer and trilayer transition metal dichalcogenides,
+and monolayer gallium selenide. Our finding points to a new route towards
+electrical and thermal generations of spin and valley currents for spintronic
+and valleytronic applications based on 2D quantum materials.",1406.2931v1
+2014-06-19,Spin-Flop Phenomenon of Two-Dimensional Frustrated Antiferromagnets without Anisotropy in Spin Space,"Motivated by a recent finding of a spin-flop phenomenon in a system without
+anisotropy in spin space reported in the S=1/2 Heisenberg antiferromagnet on
+the square-kagome lattice, we study the S=1/2 Heisenberg antiferromagnets on
+two other lattices composed of vertex-sharing triangles by the numerical
+diagonalization method. One is a novel lattice including a shuriken shape with
+four teeth; the other is the kagome lattice with
+$\sqrt{3}\times\sqrt{3}$-structure distortion, which includes a shuriken shape
+with six teeth. We find in the magnetization processes of these systems that a
+magnetization jump accompanied by a spin-flop phenomenon occurs at the
+higher-field-side edge of the magnetization plateau at one-third the height of
+saturation. This finding indicates that the spin-flop phenomenon found in the
+isotropic system on the square-kagome lattice is not an exceptional case.",1406.4964v1
+2014-06-19,Broken symmetries in URu2Si2,"To resolve the nature of the hidden order below 17.5\,K in the heavy fermion
+compound URu$_2$Si$_2$, identifying which symmetries are broken below the
+hidden order transition is one of the most important steps. Several recent
+experiments on the electronic structure have shown that the Fermi surface in
+the hidden order phase is quite close to the result of band-structure
+calculations within the framework of itinerant electron picture assuming the
+antiferromagnetism. This provides strong evidence for the band folding along
+the c-axis with the ordering vector of $(0\,0\,1)$, corresponding to broken
+translational symmetry. In addition to this, there is growing evidence for
+fourfold rotational symmetry breaking in the hidden-order phase from
+measurements of the in-plane magnetic anisotropy and the effective mass
+anisotropy in the electronic structure, as well as the orthorhombic lattice
+distortion. This broken fourfold symmetry gives a stringent constraint that the
+symmetry of the hidden order parameter should belong to the degenerate $E$-type
+irreducible representation. We also discuss a possibility that time reversal
+symmetry is also broken, which further narrows down the order parameter that
+characterizes the hidden order.",1406.5043v1
+2014-06-25,Probing the anisotropic expansion from supernovae and GRBs in a model-independent way,"In this paper, we study the anisotropic expansion of the universe using type
+Ia supernovae Union 2.1 sample and 116 long gamma-ray bursts. The luminosity
+distance is expanded with model-independent cosmographic parameters as a
+function of $z/(1+z)$ directly. Thus the results are independent of cosmology
+model. We find a dipolar anisotropy in the direction ($l=309.2^\circ \pm
+15.8^\circ$, $b=-8.6^\circ \pm 10.5^\circ$) in galactic coordinates with a
+significant evidence $97.29\%$ (more than $2~\sigma$). The magnitude is
+$(1.37\pm 0.57) \times 10^{-3}$ for the dipole, and $(2.6\pm 2.1)\times
+10^{-4}$ for the monopole, respectively. This dipolar anisotropy is more
+significant at low redshift from the redshift tomography analysis. We also test
+whether this preferred direction is caused by bulk flow motion or dark energy
+dipolar scalar perturbation. We find that the direction and the amplitude of
+the bulk flow in our results are approximately consistent with the bulk flow
+surveys. Therefore, bulk flow motion may be the main reason for the anisotropic
+expansion at low redshift, but the effect of dipolar distribution dark energy
+can not be excluded, especially at high redshift.",1406.6448v1
+2014-06-30,A Test for the Zero Mean Hypothesis in Cosmology,"One working hypothesis on which analyses of cosmological data are based is
+the zero ensemble mean hypothesis, which is related to the statistical
+homogeneity of cosmological perturbations. This hypothesis, however, should be
+tested by observational data in the current era of precision cosmology. Herein,
+we test the hypothesis by analyzing recent, foreground-reduced cosmic microwave
+background (CMB) maps, combining the spherical harmonic coefficients of the
+masked CMB temperature anisotropies in such a way that the combined variables
+can be treated as statistically independent samples. We find evidence against
+the zero mean hypothesis in two particular ranges of multipoles, with
+significance levels of $2.5 \sigma$ and $3.1 \sigma$ in the multipole ranges of
+$\ell \approx 61$-$86$ and $213$-$256$, respectively, for both the Planck and
+Wilkinson Microwave Anisotropy Probe maps. The latter signal is consistent with
+our previous result found by using brute-force Monte-Carlo simulations.
+However, within the method employed in this paper we conclude that the zero
+mean hypothesis is consistent with the current CMB data on the basis of
+Stouffer's weighted Z statistics, which takes multiple testing into account.",1406.7613v3
+2014-07-05,Nematic state stabilized by off-site Coulomb interaction in iron-based superconductors,"Using a variational Monte Carlo method, we investigate the nematic state in
+iron-base superconductors based on a three-band Hubbard model. Our results
+demonstrate that the nematic state, formed by introducing an anisotropic
+hopping order into the projected wave function, can arise in the underdoped
+regime when a realistic off-site Coulomb interaction $V$ is considered. {\color
+{red} We demonstrate that the off-site Coulomb interaction $V$, which is
+neglected so far in the analysis of iron-base superconductors, make a dominant
+contribution to the stabilization of nematic state. We calculate the doping
+dependencies of the anisotropic properties such as the unequal occupation of
+$d_{xz}$ and $d_{yz}$ orbitals, anisotropies of kinetic energy and spin
+correlations, and show that they are all suppressed upon electron doping, which
+are consistent with the intrinsic anisotropies observed by optical spectrum
+measurement and ARPES experiments.",1407.1411v1
+2014-07-08,Anisotropy of the superconducting fluctuations in multiband superconductors: the case of LiFeAs,"Between the different families of pnictide multiband superconductors, LiFeAs
+is probably one of the less understood. Indeed, despite the large amount of
+experiments performed in the last few years on this material, no consensus has
+been reached yet on the possible pairing mechanism at play in this system. Here
+we focus on the precursor effects of superconductivity visible in the transport
+experiments performed above Tc. By analyzing the superconducting fluctuations
+in a layered multiband model appropriate for this material, we argue that the
+strong two-dimensional character of the paraconductivity above Tc points
+towards a significant modulation of the pairing interactions along the z
+direction. We also discuss the peculiar differences between single-band and
+multi-band superconductors for what concerns the anisotropy of the
+superconducting-fluctuations effects above and below Tc.",1407.2187v2
+2014-07-09,On the parallel spectrum in MHD Turbulence,"Anisotropy of MHD turbulence has been studied extensively for many years,
+most prominently by measurements in the solar wind and high resolution
+simulations. The spectrum parallel to the local magnetic field was observed to
+be steeper than perpendicular spectrum, typically $k^{-2}$, consistent with the
+widely accepted Goldreich-Sridhar (1995) model. In this Letter I looked deeper
+into the nature of the relation between parallel and perpendicular spectra and
+argue that this $k^{-2}$ scaling has the same origin as the $\omega^{-2}$
+scaling of Lagrangian frequency spectrum in strong hydrodynamic turbulence.
+This follows from the fact that Alfv\'en waves propagate along magnetic field
+lines. It is now became clear that the observed anisotropy can be argued
+without invocation of the ""critical balance"" argument and is more robust that
+was previously thought. The relation between parallel (Lagrangian) and
+perpendicular (Eulerian) spectra is inevitable consequence of strong turbulence
+of Alfven waves, rather than a conjecture based on the uncertainty relation. I
+tested this using high-resolution simulations of MHD turbulence, in particular
+I verified that the cutoff of the parallel spectrum scales as Kolmogorov
+timescale, not lengthscale.",1407.2613v2
+2014-07-15,Interplay of anisotropy in shape and interactions in charged platelet suspensions,"Motivated by the intriguing phase behavior of charged colloidal platelets, we
+investigate the structure and dynamics of charged repulsive disks by means of
+Monte-Carlo simulations. The electrostatic interactions are taken into account
+through an effective two-body potential, obtained within the non-linear
+Poisson-Boltzmann formalism, which has the form of anisotropic screened Coulomb
+potential. Recently, we showed that the original intrinsic anisotropy of the
+electrostatic potential in competition with excluded volume effects leads to a
+rich phase behavior that not only includes various liquid-crsytalline phases
+but also predicts the existence of novel structures composed of alternating
+nematic-antinematic sheets. Here, we examine the structural and dynamical
+signatures of each of the observed structures for both translational and
+rotational degrees of freedom. Finally, we discuss the influence of effective
+charge value and our results in relation to experimental findings on charged
+platelet suspensions.",1407.4166v2
+2014-07-18,Evolution of shear zones in granular materials,"The evolution of wide shear zones (or shear bands) was investigated
+experimentally and numerically for quasistatic dry granular flows in split
+bottom shear cells. We compare the behavior of materials consisting of beads,
+irregular grains (e.g. sand) and elongated particles. Shearing an initially
+random sample, the zone width was found to significantly decrease in the first
+stage of the process. The characteristic shear strain associated with this
+decrease is about unity and it is systematically increasing with shape
+anisotropy, i.e. when the grain shape changes from spherical to irregular (e.g.
+sand) and becomes elongated (pegs). The strongly decreasing tendency of the
+zone width is followed by a slight increase which is more pronounced for rod
+like particles than for grains with smaller shape anisotropy (beads or
+irregular particles). The evolution of the zone width is connected to shear
+induced density change and for nonspherical particles it also involves grain
+reorientation effects. The final zone width is significantly smaller for
+irregular grains than for spherical beads.",1407.4976v2
+2014-07-20,Spintronic magnetic anisotropy,"An attractive feature of magnetic adatoms and molecules for nanoscale
+applications is their superparamagnetism, the preferred alignment of their spin
+along an easy axis preventing undesired spin reversal. The underlying magnetic
+anisotropy barrier --a quadrupolar energy splitting-- is internally generated
+by spin-orbit interaction and can nowadays be probed by electronic transport.
+Here we predict that in a much broader class of quantum-dot systems with spin
+larger than one-half, superparamagnetism may arise without spin-orbit
+interaction: by attaching ferromagnets a spintronic exchange field of
+quadrupolar nature is generated locally. It can be observed in conductance
+measurements and surprisingly leads to enhanced spin filtering even in a state
+with zero average spin. Analogously to the spintronic dipolar exchange field,
+responsible for a local spin torque, the effect is susceptible to electric
+control and increases with tunnel coupling as well as with spin polarization.",1407.5273v1
+2014-07-23,Superconducting properties of novel BiSe$_{2}$-based layered LaO$_{1-x}$F$_{x}$BiSe$_{2}$ single crystals,"F-doped LaOBiSe$_{2}$ superconducting single crystals with typical size of
+2$\times$4$\times$0.2 mm$^{3}$ are successfully grown by flux method and the
+superconducting properties are studied. Both the superconducting transition
+temperature and the shielding volume fraction are effectively improved with
+fluorine doping. The LaO$_{0.48}$F$_{0.52}$BiSe$_{1.93}$ sample exhibits
+zero-resistivity at 3.7 K, which is higher than that of the
+LaO$_{0.5}$F$_{0.5}$BiSe$_{2}$ polycrystalline sample (2.4K). Bulk
+superconductivity is confirmed by a clear specific-heat jump at the associated
+temperature. The samples exhibit strong anisotropy and the anisotropy parameter
+is about 30, as estimated by the upper critical field and effective mass model",1407.6114v1
+2014-07-25,Anisotropic magnetoresistance of charge-density wave in $o$-TaS$_3$,"We report the magnetoresistance of a charge-density wave (CDW) in $o$-TaS$_3$
+whiskers at 4.2 K under a magnetic field up to 5.2 T. An anisotropic negative
+magnetoresistance is found in the nonlinear regime of current-voltage
+characteristics. The angle dependence of the magnetoresistance, studied by
+rotating the magnetic field upon the $c$-axis, exhibited a two-fold symmetry.
+The magnetoresistance amplitude exhibits maxima when the field is parallel to
+the $a$-axis, whereas it vanishes to the $b$-axis. The observed anisotropy may
+come from difference in interchain coupling of adjacent CDWs along the $a$- and
+$b$-axes. Comparison of the anisotropy to the scanning tunneling microscope
+image of CDWs allows us to provide a simple picture to explain the
+magnetoresistance in terms of delocalization of quantum interference of CDWs
+extending over the $b$-$c$ plane.",1407.6795v2
+2014-07-30,Influence of temperature dependent shear viscosity on elliptic flow at back- and forward rapidities in ultrarelativistic heavy-ion collisions,"We explore the influence of a temperature-dependent shear viscosity over
+entropy density ratio $\eta/s$ on the azimuthal anisotropies v_2 and v_4 of
+hadrons at various rapidities. We find that in Au+Au collisions at full RHIC
+energy, $\sqrt{s_{NN}}=200$ GeV, the flow anisotropies are dominated by
+hadronic viscosity at all rapidities, whereas in Pb+Pb collisions at the LHC
+energy, $\sqrt{s_{NN}}=2760$ GeV, the flow coefficients are affected by the
+viscosity both in the plasma and hadronic phases at midrapidity, but the
+further away from midrapidity, the more dominant the hadronic viscosity is. We
+find that the centrality and rapidity dependence of the elliptic and
+quadrangular flows can help to distinguish different parametrizations of
+$(\eta/s)(T)$. We also find that at midrapidity the flow harmonics are almost
+independent of the decoupling criterion, but show some sensitivity to the
+criterion at back- and forward rapidities.",1407.8152v2
+2014-08-01,Optimization of indirect magnetoelectric effect in thin-film/substrate/piezoelectric-actuator heterostructure using polymer substrate,"Indirect magnetoelectric effect has been studied in
+magnetostrictive-film/substrate/piezoelectric-actuator heterostructures. Two
+different substrates have been employed: a flexible substrate (Young's modulus
+of 4 GPa) and a rigid one (Young's modulus of 180 GPa). A clear optimization of
+the indirect magnetoelectric coupling, studied by micro-strip ferromagnetic
+resonance, has been highlighted when using the polymer substrate. However, in
+contrast to the rigid substrate, the flexible substrate also leads to an a
+priori undesirable and huge uniaxial anisotropy which seems to be related to a
+non equibiaxial residual stress inside the magnetostrictive film. The strong
+amplitude of this non equibiaxiallity is due to the large Young's modulus
+mismatch between the polymer and the magnetostrictive film which leads to a
+slight curvature along a given direction during the elaboration process and
+thus to a large magnetoelastic anisotropy.",1408.0123v1
+2014-08-04,Azimuthal elliptic anisotropy ($v_{_{2}}$) of high-$p_{_{T}}$ direct $γ$ in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV,"Preliminary results from the STAR collaboration for the azimuthal elliptic
+anisotropy $(v_{_{2}})$ of high transverse momentum ($p_{_{T}}$) direct photons
+($\gamma_{_{dir}}$) produced at mid-rapidity ($|\eta^{\gamma_{_{dir}}}|<1$) in
+Au+Au collisions at center-of-mass energy $\sqrt{s_{_{NN}}}=200$~GeV are
+presented, and compared to the measured $(v_{_{2}})$ of neutral pions
+($\pi^{0}$) in the same kinematic range. The electromagnetic transverse shower
+profile is used to distinguish $\pi^{0}$ from direct photons. The measured
+$v_{_{2}}^{\gamma_{_{dir}}}(p_{_{T}})$ at high $p_{_{T}}$ ($8<
+p_{_{T}}^{\gamma_{_{dir}}}<20$~GeV/$c$) is found to be smaller than that of
+$\pi^{0}$ and consistent with zero when using the forward detectors in
+determining the event plane.",1408.0576v2
+2014-08-08,Effects of Lifshitz Transition on Charge Transport in Magnetic Phases of Fe-Based Superconductors,"The unusual temperature dependence of the resistivity and its in-plane
+anisotropy observed in the Fe-based superconducting materials, particularly
+Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$, has been a longstanding puzzle. Here we
+consider the effect of impurity scattering on the temperature dependence of the
+average resistivity within a simple two-band model of a dirty spin density wave
+metal. The sharp drop in resistivity below the N\'eel temperature $T_N$ in the
+parent compound can only be understood in terms of a Lifshitz transition
+following Fermi surface reconstruction upon magnetic ordering. We show that the
+observed resistivity anisotropy in this phase, arising from nematic defect
+structures, is affected by the Lifshitz transition as well.",1408.1933v3
+2014-08-11,Collective Expansion at the LHC: selected ALICE anisotropic flow measurements,"The collective expansion of matter created in collisions of heavy-ions,
+ranging from collision energies of tens of MeV to a few TeV per nucleon pair,
+proved to be one of the best probes to study the detailed properties of these
+unknown states of matter. Collective expansion originates from the initial
+pressure gradients in the created hot and dense matter. These pressure
+gradients transform the initial spatial deformations and inhomogeneities of the
+created matter into momentum anisotropies of the final state particle
+production, which we call anisotropic flow. These momentum anisotropies are
+experimentally characterised by so-called flow harmonics. In this paper I
+review ALICE measurements of the flow harmonics at the CERN Large Hadron
+Collider and discuss some of the open questions.",1408.2532v2
+2014-08-15,Solution to the cosmic ray anisotropy problem,"In the standard diffusive picture for transport of cosmic rays (CRs), a
+gradient in the CR density induces a typically small, dipolar anisotropy in
+their arrival directions. This has been widely advertised as a tool for finding
+nearby sources. However, the predicted dipole amplitude at TeV and PeV energies
+exceeds the measured one by almost two orders of magnitude. Here, we critically
+examine the validity of this prediction which is based on averaging over an
+ensemble of turbulent magnetic fields. We focus (1) on the deviations of the
+dipole in a particular random realisation from the ensemble average and (2) the
+possibility of a misalignment between the regular magnetic field and the CR
+gradient. We find that if the field direction and the gradient direction are
+close to $\sim 90^\circ$, the dipole amplitude is considerably suppressed and
+can be reconciled with observations, which sheds light on a long-standing
+problem. Furthermore, we show that the dipole direction in general does not
+coincide with the gradient direction, thus hampering the search for nearby
+sources.",1408.3630v2
+2014-08-22,Local variance asymmetries in Planck temperature anisotropy maps,"Recently, it was shown that local variance maps of temperature anisotropy are
+simple and useful tools for the study of large scale hemispherical power
+asymmetry. This was done by studying the distribution of dipoles of the local
+variance maps. In this work, we extend the study of the dipolar asymmetry in
+local variance maps using foreground cleaned Planck 143 GHz and 217 GHz data to
+smaller scales. In doing so, we include the effect of the CMB Doppler dipole.
+Further, we show that it is possible to use local variance maps to measure the
+Doppler dipole in these Planck channel maps, after removing large scale
+features (up to $l=600$), at a significance of about $3 \sigma$. At these small
+scales, we do not find any power asymmetry in the direction of the anomalous
+large scale power asymmetry beyond that expected from cosmic variance. At large
+scales, we verify previous results i.e. the presence of hemispherical power
+asymmetry at a significance of at least $3.3 \sigma$.",1408.5396v2
+2014-08-25,The mechanics of anisotropic spring networks,"We construct and analyze a model for a disordered linear spring network with
+anisotropy. The modeling is motivated by, for example, granular systems,
+nematic elastomers, and ultimately cytoskeletal networks exhibiting some
+underlying anisotropy. The model consists of a triangular lattice with two
+different bond occupation probabilities, $p_x$ and $p_y$, for the linear
+springs. We develop an effective medium theory (EMT) to describe the network
+elasticity as a function of $p_x$ and $p_y$. We find that the onset of rigidity
+in the EMT agrees with Maxwell constraint counting. We also find beyond linear
+behavior in the shear and bulk modulus as a function of occupation probability
+in the rigid phase for small strains, which differs from the isotropic case. We
+compare our EMT with numerical simulations to find rather good agreement.
+Finally, we discuss the implications of extending the reach of effective medium
+theory as well as draw connections with prior work on both anisotropic and
+isotropic spring networks.",1408.5910v2
+2014-08-28,Anisotropy study of multiferroicity in the pyroxene NaFeGe$_2$O$_6$,"We present a study of the anisotropy of the dielectric, magnetic and
+magnetoelastic properties of the multiferroic clinopyroxene NaFeGe$_2$O$_6$.
+Pyroelectric currents, dielectric constants and magnetic susceptibilities as
+well as the thermal expansion and the magnetostriction were examined on large
+synthetic single crystals of NaFeGe$_2$O$_6$. The spontaneous electric
+polarization detected below $T_{\rm C}\simeq 11.6$ K in an
+antiferromagnetically ordered state ($T_{\rm N}\simeq 13$ K) is mainly lying
+within the $ac$ plane with a small component along $b$, indicating a triclinic
+symmetry of the multiferroic phase of NaFeGe$_2$O$_6$. The electric
+polarization can be strongly modified by applying magnetic fields along
+different directions. We derive detailed magnetic-field versus temperature
+phase diagrams and identify three multiferroic low-temperature phases, which
+are separated by a non-ferroelectric, antiferromagnetically ordered state from
+the paramagnetic high-temperature phase.",1408.6772v3
+2014-08-28,Channeling Effect in Polycrystalline Deuterium-Saturated CVD Diamond Target Bombarded by Deuterium Ion Beam,"At the ion accelerator HELIS at the LPI, the neutron yield is investigated in
+DD reactions within a polycrystalline deuterium-saturated CVD diamond, during
+an irradiation of its surface by a deuterium ion beam with the energy less than
+30 keV. The measurements of the neutron flux in the beam direction are
+performed in dependence on the target angle, \b{eta}, with respect to the beam
+axis. These measurements are performed using a multichannel detector based on
+He3 counters. A significant anisotropy in neutron yield is observed, it was
+higher by a factor of 3 at \b{eta}=0 compared to that at \b{eta} = +-45{\deg}.
+The possible reasons for the anisotropy, including ion channeling, are
+discussed.",1408.7109v2
+2014-09-01,The effects of a non-zero cosmological constant on the Veltmann models,"The Veltmann models, which include the Plummer and Hernquist models as
+special cases, are studied in the presence of a cosmological constant.
+Physically relevant quantities such as the velocity dispersion profiles and the
+anisotropy parameter are computed through the use of the self-consistent
+approach. The cutoff radii for these models and the mass contained within this
+volume are also calculated. It is shown that the inclusion of a cosmological
+constant leads to many observable quantities such as the surface density,
+dispersion profiles and the anisotropy parameter becoming increasingly
+modified. In some scenarios, they are easily distinguished from the case where
+the cosmological constant is absent, as a result of their non-monotonic
+behaviour. The effects of neighbouring gravitational systems on the central
+system are also studied, and compared against the effects arising from the
+cosmological constant. Consequently, it is suggested that the effects of a
+cosmological constant can prove to be quite important when modelling dilute
+collisionless systems.",1409.0581v1
+2014-09-05,Influence of the Anisometry of Magnetic Particles on the Isotropic-Nematic Phase Transition,"The influence of the shape anisotropy of magnetic particles on the
+isotropic-nematic phase transition was studied in ferronematics based on the
+nematic liquid crystal 4-(trans-4-n-hexylcyclohexyl)-isothiocyanato-benzene
+(6CHBT). The liquid crystal was doped with spherical or rod-like magnetic
+particles of different size and volume concentrations. The phase transition
+from isotropic to nematic phase was observed by polarizing microscope as well
+as by capacitance measurements. The influence of the concentration and the
+shape anisotropy of the magnetic particles on the isotropic-nematic phase
+transition in liquid crystal is demonstrated. The results are in a good
+agreement with recent theoretical predictions.",1409.1738v1
+2014-09-06,Magnetochiral symmetry breaking in a Möbius ring,"We show that the interaction of the magnetic subsystem of a curved magnet
+with the magnet curvature results in coupling of a topologically nontrivial
+magnetization pattern and topology of the object. The mechanism of this
+coupling is explored and illustrated by an example of ferromagnetic M\""obius
+ring, where a topologically induced domain wall appears as a ground state in
+case of strong easy-normal anisotropy. For the M\""obius geometry the
+curvilinear form of the exchange interaction produces an additional effective
+Dzyaloshinskii-like term which leads to the coupling of the magnetochirality of
+the domain wall and chirality of the M\""obius ring. Two types of domain walls
+are found, transversal and longitudinal, which are oriented across and along
+the M\""obius ring, respectively. In both cases the effect of magnetochirality
+symmetry breaking is established. The dependence of the ground state of the
+M\""obius ring on its geometrical parameters and on the value of the easy-normal
+anisotropy is explored numerically.",1409.2049v2
+2014-09-10,Clustering Fossils in Solid Inflation,"In solid inflation the single field non-Gaussianity consistency condition is
+violated. As a result, the long tensor perturbation induces observable
+clustering fossils in the form of quardupole anisotropy in large scale
+structure power spectrum. In this work we revisit the bispectrum analysis for
+the scalar-scalar-scalar and tensor-scalar-scalar for the general parameter
+space of solid. We consider the parameter space of the model in which the level
+of non-Gaussianity generated is consistent with Planck constraints.
+Specializing to this allowed range of model parameter, we calculate the
+quadrupole anisotropy induced from the long tensor perturbations on the power
+spectrum of scalar perturbations. We argue that imprints of clustering fossil
+from primordial gravitational waves on large scale structures can be detected
+from the future galaxy surveys.",1409.3004v1
+2014-09-11,Spin Wave Emission in Field-Driven Domain Wall Motion,"A domain wall (DW) in a nanowire can propagate under a longitudinal magnetic
+field by emitting spin waves (SWs). We numerically investigated the properties
+of SWs emitted by the DW motion, such as frequency and wavenumber, and their
+relation with the DW motion. For a wire with a low transverse anisotropy and in
+a field above a critical value, a DW emits SWs to both sides (bow and stern),
+while it oscillates and propagates at a low average speed. For a wire with a
+high transverse anisotropy and in a weak field, the DW emits mostly stern
+waves, while the DW distorts itself and DW center propagates forward like a
+drill at a relative high speed.",1409.3286v2
+2014-09-17,Birefringence of silica hydrogels prepared under high magnetic fields reinvestigated,"Birefringence is an indicator of structural anisotropy of materials. We
+measured the birefringence of Pb(II)-doped silica hydrogels prepared under a
+high magnetic field of various strengths. Because the silica is diamagnetic,
+one does not expect the structural anisotropy induced by a magnetic field. In
+previous work [Mori A, Kaito T, Furukawa H 2008 Mater. Lett. 62 3459-3461], we
+prepared samples in cylindrical cells made of borosilicate glass and obtained a
+preliminary result indicating a negative birefringence for samples prepared at
+5T with the direction of the magnetic field being the optic axis. We have
+measured the birefringence of Pn(II)-doped silica hydrogels prepared in square
+cross-sectional cells made of quartz and reverted the previous conclusion.
+Interestingly, the magnetic-influenced silica hydrogels measured have been
+classified into four classes: two positive birefringent ones, no birefringent
+one, and negative birefringent one. Proportionality between birefringence and
+the strength of magnetic field is seen for the former two.",1409.4846v1
+2014-09-27,Anisotropy of force distributions in sheared soft particle systems,"In this numerical study, measurements of the contact forces inside a periodic
+two-dimensional sheared system of soft frictional particles are reported. The
+distribution of normalized normal forces exhibits a gradual broadening with
+increasing the pure shear deformation, leading to a slower decay for large
+forces. The process however slows down and the distribution approaches an
+invariant shape at high shear deformations. By introducing the joint
+probability distribution in sheared configurations, it is shown that for a
+fixed direction, the force distribution decays faster than exponentially even
+in a sheared system. The overall broadening can be attributed to the averaging
+over different directions in the presence of shear-induced stress anisotropy.
+The distribution of normalized tangential forces almost preserves its shape for
+arbitrary applied strain.",1409.7804v1
+2014-09-30,Majorana Fermions in Ge/Si Hole Nanowires,"We consider Ge/Si core/shell nanowires with hole states coupled to an
+$s$-wave superconductor in the presence of electric and magnetic fields. We
+employ a microscopic model that takes into account material-specific details of
+the band structure such as strong and electrically tunable Rashba-type
+spin-orbit interaction and $g$ factor anisotropy for the holes. In addition,
+the proximity-induced superconductivity Hamiltonian is derived starting from a
+microscopic model. In the topological phase, the nanowires host Majorana
+fermions with localization lengths that depend strongly on both the magnetic
+and electric fields. We identify the optimal regime in terms of the directions
+and magnitudes of the fields in which the Majorana fermions are the most
+localized at the nanowire ends. In short nanowires, the Majorana fermions
+hybridize and form a subgap fermion whose energy is split away from zero and
+oscillates as a function of the applied fields. The period of these
+oscillations could be used to measure the dependence of the spin-orbit
+interaction on the applied electric field and the $g$ factor anisotropy.",1409.8645v2
+2014-10-03,Thermophysical Properties of Lignocellulose: A Cell-scale Study down to 41K,"Thermal energy transport is of great importance in lignocellulose pyrolysis
+for bio-fuels. The thermophysical properties of lignocellulose significantly
+affect the overall properties of bio-composites and the related thermal
+transport. In this work, cell-scale lignocellulose (mono-layer plant cells) is
+prepared to characterize their thermal properties from room temperature down to
+41 K. The thermal conductivities of cell-scale lignocellulose along different
+directions show a little anisotropy due to the cell structure anisotropy. It is
+found that with temperature going down, the volumetric specific heat of the
+lignocellulose shows a slower decreasing trend against temperature than that of
+microcrystalline cellulose, and its value is always higher than that of
+microcrystalline cellulose. The thermal conductivity of lignocellulose
+decreases with temperature from 243 K to 317 K due to increasing phonon-phonon
+scatterings. From 41 K to 243 K, the thermal conductivity rises with
+temperature and its change mainly depends on the heat capacity's change.",1410.0740v1
+2014-10-20,Anisotropic inplane spin correlation in the parent and Co-doped BaFe2As2: a neutron scattering study,"Antiferromagnetic spin fluctuations were investigated in the normal states of
+the parent ($x = 0$), under-doped ($x = 0.04$) and optimally-doped ($x = 0.06$)
+Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals using inelastic neutron
+scattering technique. For all the doping levels, quasi-two-dimensional
+antiferromagnetic fluctuations were observed as a broad peak localized at ${\it
+Q} = (1/2, 1/2, l)$. At lower energies, the peak shows an apparent anisotropy
+in the $hk0$ plane; longitudinal peak widths are considerably smaller than
+transverse widths. The anisotropy is larger for the higher doping level. These
+results are consistent with the random phase approximation (RPA) calculations
+taking account of the orbital character of the electronic bands, confirming
+that the anisotropic nature of the spin fluctuations in the normal states is
+mostly dominated by the nesting of Fermi surfaces. On the other hand, the
+quasi-two-dimensional spin correlations grow much rapidly for decreasing
+temperature in the $x = 0$ parent compound, compared to that expected for
+nearly antiferromagnetic metals. This may be another sign of the unconventional
+nature of the antiferromagnetic transition in BaFe$_2$As$_2$.",1410.5155v1
+2014-10-23,On the origin of the electronic anisotropy in iron pnicitde superconductors,"We use polarization-resolved Raman spectroscopy to study the anisotropy of
+the electronic characteristics of the iron-pnictide parent compounds
+$A$Fe$_{2}$As$_{2}$ ($A$~=~Eu, Sr). We demonstrate that above the structural
+phase transition at Ts the dynamical anisotropic properties of the 122
+compounds are governed by the emergence of $xy$-symmetry critical collective
+mode foretelling a condensation into a state with spontaneously broken
+four-fold symmetry at a temperature $T^{*}$. However, the mode's critical
+slowing down is intervened by a structural transition at Ts, about 80~K above
+$T^{*}$, resulting in an anisotropic density wave state.",1410.6452v1
+2014-10-24,Magnetic Excitations in the Spin-Spiral State of TbMnO$_3$ and DyMnO$_3$,"We calculate spectra of magnetic excitations in the spin-spiral state of
+perovskite manganates. The spectra consist of several branches corresponding to
+different polarizations and different ways of diffraction from the static
+magnetic order. Goldstone modes and opening of gaps at zero and non-zero
+energies due to the crystal field and the Dzyaloshinski-Moriya anisotropies are
+discussed. Comparing results of the calculation with available experimental
+data we determine values of effective exchange parameters and anisotropies. To
+simplify the spin-wave calculation and to get a more clear physical insight in
+the structure of excitations we use the {\sigma}-model-like effective field
+theory to analyze the Heisenberg Hamiltonian and to derive the spectra.",1410.6598v1
+2014-10-24,Anisotropic hydrodynamics for conformal Gubser flow,"We derive the equations of motion for a system undergoing boost-invariant
+longitudinal and azimuthally-symmetric transverse ""Gubser flow"" using
+leading-order anisotropic hydrodynamics. This is accomplished by assuming that
+the one-particle distribution function is ellipsoidally-symmetric in the
+momenta conjugate to the de Sitter coordinates used to parameterize the Gubser
+flow. We then demonstrate that the SO(3)_q symmetry in de Sitter space further
+constrains the anisotropy tensor to be of spheroidal form. The resulting system
+of two coupled ordinary differential equations for the de Sitter-space momentum
+scale and anisotropy parameter are solved numerically and compared to a
+recently obtained exact solution of the relaxation-time-approximation Boltzmann
+equation subject to the same flow. We show that anisotropic hydrodynamics
+describes the spatio-temporal evolution of the system better than all currently
+known dissipative hydrodynamics approaches. In addition, we prove that
+anisotropic hydrodynamics gives the exact solution of the relaxation-time
+approximation Boltzmann equation in the ideal, eta/s -> 0, and free-streaming,
+eta/s -> infinity, limits.",1410.6790v2
+2014-10-27,Relativistic anisotropic star and its maximum mass in higher dimensions,"We present a class of relativistic solutions of cold compact anisotropic
+stars in hydrostatic equilibrium in the framework of higher dimensions using
+spheroidal geometry. The solutions obtained with Vaidya-Tikekar metric are used
+to construct stellar models of compact objects and studied their physical
+features. The effects of anisotropy and extra dimensions on the global
+properties namely, compactness, mass, radius, equation of state are determined
+in higher dimensions in terms of the spheroidicity parameter ($\lambda$). It is
+noted that for a given configuration, compactness of a star is found smaller in
+higher dimensions compared to that in four space-time dimensions. It is also
+noted that the maximum mass of compact objects increase with the increase of
+space-time dimensions which however attains a maximum when $D=5$ for a large
+($\lambda=100$), thereafter it decreases as one increases number of extra
+dimensions. The effect of extra dimensions on anisotropy is also studied.",1410.7735v1
+2014-11-02,Convergence of Space-Time Discrete Threshold Dynamics to Anisotropic Motion by Mean Curvature,"We analyze the continuum limit of a thresholding algorithm for motion by mean
+curvature of one dimensional interfaces in various space-time discrete regimes.
+The algorithm can be viewed as a time-splitting scheme for the Allen-Cahn
+equation which is a typical model for the motion of materials phase boundaries.
+Our results extend the existing statements which are applicable mostly in
+semi-discrete (continuous in space and discrete in time) settings. The
+motivations of this work are twofolds: to investigate the interaction between
+multiple small parameters in nonlinear singularly perturbed problems, and to
+understand the anisotropy in curvature for interfaces in spatially discrete
+environments. In the current work, the small parameters are the the spatial and
+temporal discretization step sizes $\triangle x = h$ and $\triangle t = \tau$.
+We have identified the limiting description of the interfacial velocity in the
+(i) sub-critical ($h \ll \tau$), (ii) critical ($h = O(\tau)$), and (iii)
+super-critical ($h \gg \tau$) regimes. The first case gives the classical
+isotropic motion by mean curvature, while the second produces intricate pinning
+and de-pinning phenomena and anisotropy in the velocity function of the
+interface. The last case produces no motion (complete pinning).",1411.0301v1
+2014-11-10,Spin-dependent thermoelectric effects in transport through a nanoscopic junction involving spin impurity,"Conventional and spin-related thermoelectric effects in transport through a
+magnetic tunnel junction with a large-spin impurity, such as a magnetic
+molecule or atom, embedded into the corresponding barrier are studied
+theoretically in the linear-response regime. The impurity is described by the
+giant spin Hamiltonian, with both uniaxial and transverse magnetic anisotropy
+taken into account. Owing to the presence of transverse component of magnetic
+anisotropy, spin of a tunneling electron can be reversed during scattering on
+the impurity, even in the low temperature regime. This reversal appears due to
+exchange interaction of tunneling electrons with the magnetic impurity. We
+calculate Seebeck and spin Seebeck coefficients, and analyze their dependence
+on various parameters of the spin impurity and tunnel junction. In addition,
+conventional and spin figures of merit, as well as the electronic contribution
+to heat conductance are considered. We also show that pure spin current can be
+driven by a spin bias applied to the junction with spin impurity, even if no
+electron transfer between the electrodes can take place. The underlying
+mechanism employs single-electrode tunneling processes (electrode-spin exchange
+interaction) and the impurity as an intermediate reservoir of angular momentum.",1411.2375v1
+2014-11-14,Femtosecond wavepacket interferometry using the rotational dynamics of a trapped cold molecular ion,"A Ramsey-type interferometer is suggested, employing a cold trapped ion and
+two time-delayed off-resonant femtosecond laser pulses. The laser light couples
+to the molecular polarization anisotropy, inducing rotational wavepacket
+dynamics. An interferogram is obtained from the delay dependent populations of
+the final field-free rotational states. Current experimental capabilities for
+cooling and preparation of the initial state are found to yield an
+interferogram visibility of more than 80\%. The interferograms can be used to
+determine the polarizability anisotropy with an accuracy of about $\pm 2\%$,
+respectively $\pm 5\%$, provided the uncertainty in the initial populations and
+measurement errors are confined to within the same limits.",1411.3849v1
+2014-11-17,The three-dimensional evolution of ion-scale current sheets: tearing and drift-kink instabilities in the presence of proton temperature anisotropy,"We present the first three-dimensional hybrid simulations of the evolution of
+ion-scale current sheets, with an investigation of the role of temperature
+anisotropy and associated kinetic instabilities on the growth of the tearing
+instability and particle heating. We confirm the ability of the ion cyclotron
+and firehose instabilities to enhance or suppress reconnection, respectively.
+The simulations demonstrate the emergence of persistent three-dimensional
+structures, including patchy reconnection sites and the fast growth of a
+narrow-band drift-kink instability, which suppresses reconnection for thin
+current sheets with weak guide fields. Potential observational signatures of
+the three-dimensional evolution of solar wind current sheets are also
+discussed. We conclude that kinetic instabilities, arising from non-Maxwellian
+ion populations, are significant to the evolution of three-dimensional current
+sheets, and two-dimensional studies of heating rates by reconnection may
+therefore over-estimate the ability of thin, ion-scale current sheets to heat
+the solar wind by reconnection.",1411.4422v1
+2014-11-19,Universal domain wall dynamics under electric field in Ta/CoFeB/MgO devices with perpendicular anisotropy,"Electric field effects in ferromagnetic/oxide dielectric structures provide a
+new route to control domain wall (DW) dynamics with low power dissipation.
+However, electric field effects on DW velocities have only been observed so far
+in the creep regime where DW velocities are low due to strong interactions with
+pinning sites. Here, we show gate voltage modulation of DW velocities ranging
+from the creep to the flow regime in Ta/Co40Fe40B20/MgO/TiO2 structures with
+perpendicular magnetic anisotropy. We demonstrate a universal description of
+the role of applied electric fields in the various pinning dependent regimes by
+taking into account an effective magnetic field being linear with the electric
+field. In addition, the electric field effect is found to change sign in the
+Walker regime. Our work opens new opportunities for the study and optimization
+of electric field effect at ferromagnetic metal/insulator interfaces.",1411.5267v2
+2014-11-20,Residence time estimates for asymmetric simple exclusion dynamics on stripes,"The target of our study is to approximate numerically and, in some particular
+physically relevant cases, also analytically, the residence time of particles
+undergoing an asymmetric simple exclusion dynamics on a stripe. The source of
+asymmetry is twofold: (i) the choice of boundary conditions (different
+reservoir levels) and (ii) the strong anisotropy from a nonlinear drift with
+prescribed directionality. We focus on the effect of the choice of anisotropy
+in the flux on the asymptotic behavior of the residence time with respect to
+the length of the stripe. The topic is relevant for situations occurring in
+pedestrian flows or biological transport in crowded environments, where lateral
+displacements of the particles occur predominantly affecting therefore in an
+essentially way the efficiency of the overall transport mechanism.",1411.5490v2
+2014-11-24,Anisotropy of the semi-classical gluon field of a large nucleus at high energy,"The McLerran-Venugopalan model describes a highly boosted hadron/nucleus as a
+sheet of random color charges which source soft classical Weizs\""acker-Williams
+gluon fields. We show that due to fluctuations, individual configurations are
+azimuthally anisotropic. We present initial evidence that impact parameter
+dependent small-x JIMWLK resummation preserves such anisotropies over several
+units of rapidity. Finally, we compute the first four azimuthal Fourier
+amplitudes of the S-matrix of a fundamental dipole in such background fields.",1411.6630v3
+2014-11-26,(3+1)-dimensional framework for leading-order non conformal anisotropic hydrodynamics,"In this work I develop a new framework for anisotropic hydrodynamics that
+generalizes the leading order of the hydrodynamic expansion to the full
+(3+1)-dimensional anisotropic massive case. Following previous works, my
+considerations are based on the Boltzmann kinetic equation with the collisional
+term treated in the relaxation time approximation. The momentum anisotropy is
+included explicitly in the leading term, allowing for a large difference
+between the longitudinal and transverse pressures as well as for non trivial
+transverse dynamics. Energy and momentum conservation is expressed by the first
+moment of the Boltzmann equation. The system of equations is closed by using
+the zeroth and second moments of the Boltzmann equation. The
+close-to-equilibrium matching with second-order viscous hydrodynamics is
+demonstrated. In particular, I show that the coupling between shear and bulk
+pressure corrections, recently proved to be important for an accurate
+description of momentum anisotropy and bulk viscous dynamics, does not vanish
+in the close-to-equilibrium limit.",1411.7268v2
+2014-11-27,New formulation of leading order anisotropic hydrodynamics,"Anisotropic hydrodynamics is a reorganization of the relativistic
+hydrodynamics expansion, with the leading order already containing substantial
+momentum-space anisotropies. The latter are a cause of concern in the
+traditional viscous hydrodynamics, since large momentum anisotropies generated
+in ultrarelativistic heavy-ion collisions are not consistent with the
+hypothesis of small deviations from an isotropic background, i.e., from the
+local equilibrium distribution.
+  We discuss the leading order of the expansion, presenting a new formulation
+for the (1+1)--dimensional case, namely, for the longitudinally boost invariant
+and cylindrically symmetric flow. This new approach is consistent with the well
+established framework of Israel and Stewart in the close to equilibrium limit
+(where we expect viscous hydrodynamics to work well). If we consider the
+(0+1)--dimensional case, that is, transversally homogeneous and longitudinally
+boost invariant flow, {the new form of anisotropic hydrodynamics leads to
+better agreement with known solutions} of the Boltzmann equation than the
+previous formulations, especially when we consider finite mass particles.",1411.7615v1
+2014-11-28,Cosmic ray propagation in the interstellar magnetic fields,"The propagation of TeV-PeV cosmic rays (CR) in our Galaxy can be described as
+a diffusive process. We discuss here two effects, with important observational
+consequences, that cannot be predicted by the diffusion approximation in its
+usual form. First, we present an explanation for the CR anisotropies observed
+at small angular scales on the sky. We show that the local magnetic field
+configuration within a CR mean free path from Earth naturally results in CR
+flux anisotropies at small and medium scales. Second, we point out that TeV-PeV
+CRs should be expected to diffuse strongly anisotropically in the interstellar
+medium on scales smaller than the maximum scale of spatial fluctuations of the
+field, $\sim 100$ pc. This notably questions the usual assumptions on CR
+diffusion around sources.",1411.7985v1
+2014-12-02,Quantum Criticality in the 122 Iron Pnictide Superconductors Emerging from Orbital-Selective Mottness,"The twin issues of the nature of the normal state and competing order(s) in
+the iron arsenides are central to understanding their unconventional, high-Tc
+superconductivity. We use a combination of transport anisotropy measurements on
+detwinned Sr(Fe(1-x)Co(x))2As2 single crystals and local density approximation
+plus dynamical mean field theory (LDA + DMFT) calculations to revisit these
+issues. The peculiar resistivity anisotropy and its evolution with x are
+naturally interpreted in terms of an underlying orbital-selective Mott
+transition (OSMT) that gaps out the dxz or dyz states. Further, we use a
+Landau-Ginzburg approach using LDA + DMFT input to rationalize a wide range of
+anomalies seen up to optimal doping, providing strong evidence for secondary
+electronic nematic order. These findings suggest that strong dynamical
+fluctuations linked to a marginal quantum-critical point associated with this
+OSMT and a secondary electronic nematic order constitute an intrinsically
+electronic pairing mechanism for superconductivity in Fe arsenides.",1412.1034v2
+2014-12-05,Quantum metrology with non-equilibrium steady states of quantum spin chains,"We consider parameter estimations with probes being the boundary
+driven/dissipated non- equilibrium steady states of XXZ spin 1/2 chains. The
+parameters to be estimated are the dissipation coupling and the anisotropy of
+the spin-spin interaction. In the weak coupling regime we compute the scaling
+of the Fisher information, i.e. the inverse best sensitivity among all
+estimators, with the number of spins. We find superlinear scalings and
+transitions between the distinct, isotropic and anisotropic, phases. We also
+look at the best relative error which decreases with the number of particles
+faster than the shot-noise only for the estimation of anisotropy.",1412.1977v1
+2014-12-07,Pressure-Induced Enhancement of the Magnetic Anisotropy in Mn(N(CN)$_{2}$)$_{2}$,"Using dc and ac magnetometry, the pressure dependence of the magnetization of
+the three-dimensional antiferromagnetic coordination polymer
+Mn(N(CN)$_{2}$)$_{2}$ was studied up to 12 kbar and down to 8K. The magnetic
+transition temperature, $T_c$, increases dramatically with applied pressure
+$(P)$, where a change from $T_c(P=\text{ambient}) = 16.0$ K to
+$T_c(P=12.1$~kbar$) = 23.5$ K was observed. In addition, a marked difference in
+the magnetic behavior is observed above and below 7.1 kbar. Specifically, for
+$P<7.1$ kbar, the differences between the field-cooled and zero-field-cooled
+(fc-zfc) magnetizations, the coercive field, and the remanent magnetization
+decrease with increasing pressure. However, for $P>7.1$ kbar, the behavior is
+inverted. Additionally, for $P>8.6$ kbar, minor hysteresis loops are observed.
+All of these effects are evidence of the increase of the superexchange
+interaction and the appearance of an enhanced exchange anisotropy with applied
+pressure.",1412.2318v1
+2014-12-11,Non-collinear Magnetic Configurations at Finite Temperature in Thin Films,"The finite-temperature magnetism of a monolayer on a bcc (110) surface was
+examined using a model Hamiltonian containing ferromagnetic or
+antiferromagnetic exchange interactions, Dzyaloshinsky-Moriya interactions and
+easy-axis on-site anisotropy. We examined the competition between the collinear
+ground state parallel to the easy axis and the spin spiral state in the plane
+perpendicular to this axis preferred by the Dzyaloshinsky-Moriya interaction.
+Using approximative methods to calculate the magnon spectrum at finite
+temperatures, it was found that even if the ground state is collinear,
+increasing the Dzyaloshinsky-Moriya interaction strongly decreases the critical
+temperature where this collinear order disappears. Using atomistic spin
+dynamics simulations it was found that at this critical temperature the system
+transforms into the non-collinear state. Including external magnetic field
+helps stabilising the ferromagnetic state. An effect due to the finite size of
+the magnetic monolayer was included in the model by considering a different
+value for the anisotropy at the edges of the monolayer. This effect was shown
+to stabilize the spin spiral state by fixing the phase at the ends of the
+stripe.",1412.3591v1
+2014-12-14,Dielectric anisotropy in polar solvents under external fields,"We investigate dielectric saturation and increment in polar liquids under
+external fields. We couple a previously introduced dipolar solvent model to a
+uniform electric field and derive the electrostatic kernel of interacting
+dipoles. This procedure allows an unambiguous definition of the liquid
+dielectric permittivity embodying non-linear dielectric response and
+correlation effects.We find that the presence of the external field results in
+a dielectric anisotropy characterized by a two-component dielectric
+permittivity tensor. The increase of the electric field amplifies the
+permittivity component parallel to the field direction, i.e. dielectric
+increment is observed along the field. However, the perpendicular component is
+lowered below the physiological permittivity, indicating dielectric saturation
+perpendicular to the field. By comparison with Molecular Dynamics simulations
+from the literature, we show that the mean-field level dielectric response
+theory underestimates dielectric saturation. The inclusion of dipolar
+correlations at the weak-coupling level intensify the mean-field level
+dielectric saturation and improves the agreement with simulation data at weak
+electric fields. The correlation-corrected theory predicts as well the presence
+of a metastable configuration corresponding to the antiparallel alignment of
+dipoles with the field. This prediction can be verified by solvent-explicit
+simulations where solvent molecules are expected to be trapped transiently in
+this metastable state.",1412.4425v2
+2014-12-16,Calculating thermal stability and attempt frequency of advanced recording structures without free parameters,"Ensuring a permanent increase of magnetic storage densities is one of the
+main challenges in magnetic recording. Conventional approaches based on single
+phase grains are not suitable to achieve this goal, because their grain volume
+is limited due to the superparamagnetic limit. Grains with graded anisotropy
+are the most promising candidates to overcome this limit, providing magnetic
+memory bits with small volumes, low coercivity and high thermal stability at
+the same time. Combining micromagnetic simulations with forward flux sampling
+(FFS), a computational method for rare events that has been recently applied to
+the magnetic nanostructures, we have determined thermal escape rates and
+attempt frequencies of a graded media grain and two single phase grains of the
+same geometry. We find that graded anisotropy can increase the thermal
+stability of a grain by 12 orders of magnitudes from tens of milliseconds to
+centuries without changing the coercive field.",1412.5057v1
+2014-12-23,Anisotropic Thermal Conductivity in Single Crystal beta-Gallium Oxide,"The thermal conductivities of beta-Ga2O3 single crystals along four different
+crystal directions were measured in the temperature range of 80-495K using the
+time domain thermoreflectance (TDTR) method. A large anisotropy was found. At
+room temperature, the [010] direction has the highest thermal conductivity of
+27.0+/-2.0 W/mK, while that along the [100] direction has the lowest value of
+10.9+/-1.0 W/mK. At high temperatures, the thermal conductivity follows a ~1/T
+relationship characteristic of Umklapp phonon scattering, indicating
+phonon-dominated heat transport in the \b{eta}-Ga2O3 crystal. The measured
+experimental thermal conductivity is supported by first-principles calculations
+which suggest that the anisotropy in thermal conductivity is due to the
+differences of the speed of sound along different crystal directions.",1412.7472v1
+2014-12-25,Full decoherence induced by local fields in open spin chains with strong boundary couplings,"We investigate an open $XYZ$ spin $1/2$ chain driven out of equilibrium by
+boundary reservoirs targeting different spin orientations, aligned along the
+principal axes of anisotropy. We show that by tuning local magnetic fields,
+applied to spins at sites near the boundaries, one can change any
+nonequilibrium steady state to a fully uncorrelated Gibbsian state at infinite
+temperature. This phenomenon occurs for strong boundary coupling and on a
+critical manifold in the space of the fields amplitudes. The structure of this
+manifold depends on the anisotropy degree of the model and on the parity of the
+chain size.",1412.7841v1
+2014-12-29,Drag force of Anisotropic plasma at finite $U(1)$ chemical potential,"We perform the calculation of drag force acting on a massive quark moving
+through an anisotropic ${\cal N}=4$ SU(N)= 4 SU(N) Super Yang-Mills plasma in
+the presence of a U(1) chemical potential. We present the numerical results for
+any value of anisotropy and arbitrary direction of the quark velocity with
+respect to the direction of anisotropy. We find the effect of chemical
+potential or charge density will enhance the drag force for the our charged
+solution.",1412.8433v5
+2015-01-05,Anisotropic flow generated by hard partons in medium,"Hard partons which are produced copiously in nuclear collisions at the LHC,
+deposit most of their energy and momentum into the surrounding quark-gluon
+plasma. We show that this generates streams in the plasma and contributes
+importantly to flow anisotropies. With the help of event-by-event
+three-dimensional perfect hydrodynamic simulations we calculate the observable
+azimuthal anisotropies of hadronic distributions and show that the proposed
+mechanism is capable of generating non-negligible part of the observed signal.
+Hence, it must be taken into account in quantitative studies in which one tries
+to extract the values of viscosities from the comparison of simulated results
+with measured data.",1501.00788v1
+2015-01-09,The ground-state phase diagram of the XXZ spin-s kagome antiferromagnet: A coupled-cluster study,"We use the coupled cluster method to high orders of approximation in order to
+calculate the ground-state phase diagram of the XXZ spin-$s$ kagome
+antiferromagnet with easy-plane anisotropy, i.e. the anisotropy parameter
+$\Delta$ varies between $\Delta=1$ (isotropic Heisenberg model) and $\Delta=0$
+($XY$ model). We find that for the extreme quantum case $s=1/2$ the ground
+state is magnetically disordered in the entire region $0 \le \Delta \le 1$. For
+$s=1$ the ground state is disordered for $0.818 < \Delta \le 1$, it exhibits
+$\sqrt{3}\times\sqrt{3}$ magnetic long-range order for $0.281 < \Delta <0.818$,
+and $q=0$ magnetic long-range order for $0 \le \Delta < 0.281$. We confirm the
+recent result of Chernyshev and Zhitomirsky (Phys. Rev. Lett. 113, 237202
+(2014)) that the selection of the ground state by quantum fluctuations is
+different for small $\Delta$ ($XY$ limit) and for $\Delta$ close to one
+(Heisenberg limit), i.e., $q=0$ magnetic order is favored over
+$\sqrt{3}\times\sqrt{3}$ for $0\le \Delta <\Delta_c$ and vice versa for
+$\Delta_c < \Delta \le 1$. We calculate $\Delta_c$ as a function of the spin
+quantum number $s$.",1501.02146v1
+2015-01-09,Spin Hall Switching of the Magnetization in Ta/TbFeCo Structures with Bulk Perpendicular Anisotropy,"Spin-orbit torques are studied in Ta/TbFeCo patterned structures with a bulk
+perpendicular magnetic anisotropy (bulk-PMA) for the first time. The
+current-induced magnetization switching is investigated in the presence of a
+perpendicular, longitudinal, or transverse field. In order to rule out Joule
+heating effect, switching of the magnetization is also demonstrated using
+current pulses. It is found that the anti-damping torque correlated with spin
+Hall effect is very strong, and a spin Hall angle of about 0.12 is obtained.
+The field-like torque related with Rashba effect is negligible in this
+structure suggesting that the interface play a significant role in Rashba-like
+torque.",1501.02294v1
+2015-01-14,Hydrodynamic spin fluctuations in the antiferromagnetic Heisenberg chain,"We study the finite temperature, low energy, long wave-length spectrum of the
+dynamic structure factor of the spin-$1/2$ antiferromagnetic Heisenberg chain
+in the presence of exchange anisotropy and external magnetic fields. Using
+imaginary-time quantum Monte-Carlo we extract parameters, relevant to
+characterize a {\it renormalized} Luttinger liquid. For small momentum our
+results are consistent with a change from propagating spinon density waves to
+spin diffusion, described by a finite-frequency spin-current relaxation rate.
+Results for this relaxation rate as well as other Luttinger liquid parameters
+are presented versus temperature, momentum, magnetic field, and anisotropy,
+including finite-size analysis, and checks for anomalous diffusion. Our results
+are consistent with exact diagonalization and Bethe Ansatz, where available,
+and with corroborate findings of other previous studies using bosonization,
+transfer matrix renormalization group, and quantum Monte-Carlo.",1501.03447v1
+2015-01-17,Competition between Coulomb and Symmetry Potential in Semi-peripheral Heavy-ion Collisions,"The anisotropy of angular distributions of emitted nucleons and light charged
+particles for the asymmetric reaction system, $^{40}$Ar+$^{197}$Au, at b=6fm
+and $E_{beam}$=35, 50 and 100MeV/u, are investigated by using the Improved
+Quantum Molecular Dynamics model. The competition between the symmetry
+potential and Coulomb potential shows large impacts on the nucleons and light
+charged particles emission in projectile and target region. As a result of this
+competition, the angular distribution anisotropy of coalescence invariant
+Y(n)/Y(p) ratio at forward regions shows sensitivity to the stiffness of
+symmetry energy as well as the value of Y(n)/Y(p). This observable can be
+further checked against experimental data to understand the reaction mechanism
+and to extract information about the symmetry energy at subsaturation
+densities.",1501.04178v1
+2015-01-22,Azimuthal harmonics of color fields in a high energy nucleus,"Recent experimental results have revealed a surprisingly rich structure of
+multiparticle azimuthal correlations in high energy proton-nucleus collisions.
+Final state collective effects can be responsible for many of the observed
+effects, but it has recently been argued that a part of these correlations are
+present already in the wavefunctions of the colliding particles. We evaluate
+the momentum space 2-particle cumulant azimuthal anisotropy coefficients
+v_n{2}, n=2,3,4 from fundamental representation Wilson line distributions
+describing the high energy nucleus. These would correspond to the flow
+coefficients in very forward proton nucleus scattering. We find significant
+differences beteen Wilson lines from the MV model and from JIMWLK evolution.
+The magnitude and transverse momentum dependence of the v_n{2} values suggest
+that the fluctuations present in the initial fields are a significant
+contribution to the observed anisotropies.",1501.05505v2
+2015-01-16,$v_2$ of charged hadrons in a`soft + hard' model for PbPb collisions at $\sqrt s$ = 2.76 ATeV,"We describe transverse spectra as well as azimuthal anisotropy ($v_2$) of
+charged hadrons stemming from various centrality PbPb collisions at $\sqrt s$ =
+2.76 ATeV analytically in a `soft + hard' model. In this model, we propose that
+hadron yields produced in heavy-ion collisions are simply the sum of yields
+stemming from jets (hard yields) and yields stemming from the Quark-Gluon
+Plasma (soft yields). The hadron spectra in both types of yields are
+approximated by the Tsallis distribution. It is found that the anisotropy
+decreases for more central collisions.",1501.05959v1
+2015-01-28,Two-body state with p-wave interaction in one-dimensional waveguides under transversely anisotropic confinement,"We theoretically study two atoms with $p$-wave interaction in a
+one-dimensional waveguide, and investigate how the transverse anisotropy of the
+confinement affects the two-body state, especially, the properties of the
+resonance. For bound-state solution, we find there are totally three two-body
+bound states due to the richness of the orbital magnetic quantum number of
+$p$-wave interaction, while only one bound state is supported by $s$-wave
+interaction. Two of them become nondegenerate due to the breaking of the
+rotation symmetry under transversely anisotropic confinement. For scattering
+solution, the effective one-dimensional scattering amplitude and scattering
+length are derived. We find the position of the $p$-wave confinement-induced
+resonance shifts apparently as the transverse anisotropy increases. In
+addition, a two-channel mechanism for confinement-induced resonance in a
+one-dimensional waveguide is generalized to $p$-wave interaction, which was
+proposed only for $s$-wave interaction before. All our calculations are based
+on the parameterization of the $^{40}$K atom experiments, and can be confirmed
+in future experiments.",1501.06971v1
+2015-01-29,Anisotropic critical-state model of type-II superconducting slabs,"We introduce a critical-state model incorporating the anisotropy of flux-line
+pinning to analyze the critical states developing in an anisotropic biaxial
+superconducting slab exposed to a uniform perpendicular magnetic field and to
+two crossed in-plane magnetic fields which are applied successively. The theory
+is an extension of the anisotropic collective pinning theory developed by
+Mikitik and Brandt. The anisotropic flux-line pinning enters into the critical
+states by generating the angular dependence of the critical current density and
+by deviating the direction of the electric field from the current in the plane
+perpendicular to the vortex line. We find that an enhanced in-plane anisotropy
+moderates the gradients of the magnitudes of the magnetic field and the
+electric field along the slab thickness, however increases the gradients of
+their rotations.",1501.07355v2
+2015-01-30,Microscopic properties of degradation-free capped GdN thin films studied by Electron Spin Resonance,"The microscopic magnetic properties of high-quality GdN thin films have been
+investigated by electron spin resonance (ESR) and ferromagnetic resonance (FMR)
+measurements. Detailed temperature dependence ESR measurements have shown the
+existence of two ferromagnetic components at lower temperatures which was not
+clear from the previous magnetization measurements. The temperature, where the
+resonance shift occurs for the major ferromagnetic component, seems to be
+consistent with the Curie temperature obtained from the previous magnetization
+measurement. On the other hand, the divergence of line width is observed around
+57 K for the minor ferromagnetic component. The magnetic anisotropies of GdN
+thin films have been obtained by the analysis of FMR angular dependence
+observed at 4.2 K. Combining the X-ray diffraction results, the correlation
+between the magnetic anisotropies and the lattice constants is discussed.",1501.07672v1
+2015-02-03,Anisotropy tuned magnetic order in pyrochlore iridates,"The magnetic behavior of polycrystalline samples of Er$_2$Ir$_2$O$_7$ and
+Tb$_2$Ir$_2$O$_7$ pyrochlores is studied by magnetization measurements and
+neutron diffraction. Both compounds undergo a magnetic transition at 140 and
+130 K respectively, associated with an ordering of the Ir sublattice, signaled
+by thermomagnetic hysteresis. In Tb$_2$Ir$_2$O$_7$, we show that the Ir
+molecular field leads the Tb magnetic moments to order below 40 K in the
+all-in/all-out magnetic arrangement. No sign of magnetic long range order on
+the Er sublattice is evidenced in Er$_2$Ir$_2$O$_7$ down to 0.6 K where a spin
+freezing is detected. These contrasting behaviors result from the competition
+between the Ir molecular field and the different single-ion anisotropy of the
+rare-earths on which it is acting. Additionally, this strongly supports the
+all-in/all-out iridium magnetic order.",1502.00787v1
+2015-02-05,Domain structure and perpendicular magnetic anisotropy in CoFe/Pd multilayers using off-axis electron holography,"Multilayers of Co90Fe10/Pd with different bilayer thicknesses, have been
+deposited by dc-magnetron sputtering on thermally oxidized Si wafers.
+Transmission electron microscopy showed that the highly textured crystalline
+films had columnar structure, while scanning transmission electron microscopy
+and atomic force microscopy respectively indicated some layer waviness and
+surface roughness. The magnetic domain structure and perpendicular magnetic
+anisotropy (PMA) of the Co90Fe10/Pd multilayers were investigated by off-axis
+electron holography and magnetic force microscopy. The Co90Fe10 layer thickness
+was the primary factor determining the magnetic domain size and the
+perpendicular magnetization: both decreased as the thickness increased. The
+strongest PMA was observed in the sample with the thinnest magnetic layer of
+0.45 nm.",1502.01422v1
+2015-02-06,Fast Magnetic Reconnection Due to Anisotropic Electron Pressure,"A new regime of fast magnetic reconnection with an out-of-plane (guide)
+magnetic field is reported in which the key role is played by an electron
+pressure anisotropy described by the Chew-Goldberger-Low gyrotropic equations
+of state in the generalized Ohm's law, which even dominates the Hall term. A
+description of the physical cause of this behavior is provided and
+two-dimensional fluid simulations are used to confirm the results. The electron
+pressure anisotropy causes the out-of-plane magnetic field to develop a
+quadrupole structure of opposite polarity to the Hall magnetic field and gives
+rise to dispersive waves. In addition to being important for understanding what
+causes reconnection to be fast, this mechanism should dominate in plasmas with
+low plasma beta and a high in-plane plasma beta with electron temperature
+comparable to or larger than ion temperature, so it could be relevant in the
+solar wind and some tokamaks.",1502.01781v1
+2015-02-19,Characterization of spin relaxation anisotropy in Co using spin pumping,"Ferromagnets are believed to exhibit strongly anisotropic spin relaxation,
+with relaxation lengths for spin longitudinal to magnetization significantly
+longer than those for spin transverse to magnetization. Here we characterize
+the anisotropy of spin relaxation in Co using the spin pumping contribution to
+Gilbert damping in noncollinearly magnetized Py$_{1-x}$Cu$_{x}$/Cu/Co trilayer
+structures. The static magnetization angle between Py$_{1-x}$Cu$_{x}$ and Co,
+adjusted under field bias perpendicular to film planes, controls the
+projections of longitudinal and transverse spin current pumped from
+Py$_{1-x}$Cu$_{x}$ into Co. We find nearly isotropic absorption of pure spin
+current in Co using this technique; fits to a diffusive transport model yield
+the longitudinal spin relaxation length $< 2$ nm in Co. The longitudinal spin
+relaxation lengths found are an order of magnitude smaller than those
+determined by current-perpendicular-to-planes giant magnetoresistance
+measurements, but comparable with transverse spin relaxation lengths in Co
+determined by spin pumping.",1502.05687v3
+2015-02-18,Entanglement entropy and fidelity susceptibility in the one-dimensional spin-1 XXZ chains with alternating single-site anisotropy,"We study the fidelity susceptibility in an antiferromagnetic spin-1 XXZ chain
+numerically. By using the density-matrix renormalization group method, the
+effects of the alternating single-site anisotropy $D$ on fidelity
+susceptibility are investigated. Its relation with the quantum phase transition
+is analyzed. It is found that the quantum phase transition from the Haldane
+spin liquid to periodic N\'{e}el spin solid can be well characterized by the
+fidelity. Finite size scaling of fidelity susceptibility shows a power-law
+divergence at criticality, which indicates the quantum phase transition is of
+second order. The results are confirmed by the second derivative of the
+ground-state energy. We also study the relationship between the entanglement
+entropy, the Schmidt gap and quantum phase transitions. Conclusions drawn from
+these quantum information observables agree well with each other.",1502.05930v1
+2015-02-23,Torsion induced effects in magnetic nanowires,"Magnetic helix wire is one of the most simple magnetic systems which manifest
+properties of both curvature and torsion. There exist two equilibrium states in
+the helix wire with easy-tangential anisotropy: a quasi-tangential
+magnetization distribution in case of relatively small curvatures and torsions,
+and an onion state in opposite case. In the last case the magnetization is
+close to tangential one, deviations are caused by the torsion and curvature.
+Possible equilibrium magnetization states in the helix magnet with different
+anisotropy directions are studied theoretically. The torsion also essentially
+influences the spin-wave dynamics, acting as an effective magnetic field.
+Originated from the curvature induced effective Dzyaloshinskii interaction,
+this magnetic field leads to the coupling between the helix chirality and the
+magnetochirality, it breaks mirror symmetry in spin-wave spectrum. All
+analytical predictions on magnetization statics an dynamics are well confirmed
+by the direct spin lattice simulations.",1502.06482v3
+2015-02-23,Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity,"The present article reviews recent experimental investigations of spin
+dynamics in iron-based superconductors and their parent compounds by means of
+inelastic neutron scattering. It mainly focuses on the most contemporary
+developments in this field, pertaining to the observations of magnetic resonant
+modes in new superconductors, spin anisotropy of low-energy magnetic
+fluctuations that has now been observed in a wide range of chemical
+compositions and doping levels, as well as their momentum-space anisotropy
+incurred by the spin-nematic order. The implications of these new findings for
+our understanding of the superconducting state, along with the remaining
+unsettled challenges for neutron spectroscopy, are discussed.",1502.06570v1
+2015-02-27,"Quantum oscillations, thermoelectric coefficients and the Fermi surface of semi-metallic WTe2","We present a study of angle-resolved quantum oscillations of electric and
+thermoelectric transport coefficients in semi-metallic WTe$_{2}$, which has the
+particularity of displaying a large B$^{2}$ magneto-resistance. The Fermi
+surface consists of two pairs of electron-like and hole-like pockets of equal
+volumes in a ""Russian doll"" structure. Carrier density, Fermi energy, mobility
+and the mean-free-path of the system are quantified. An additional frequency is
+observed above a threshold field and attributed to magnetic breakdown across
+two orbits. In contrast to all other dilute metals, the Nernst signal remains
+linear in magnetic field even in the high-field ($\omega_c\tau \gg 1$) regime.
+Surprisingly, none of the pockets extend across the c-axis of the first
+Brillouin zone, making the system a three-dimensional metal with moderate
+anisotropy in Fermi velocity yet a large anisotropy in mean-free-path.",1502.07797v2
+2015-03-01,"A combined first-principles and thermodynamic approach to M-Nitronyl Nitroxide (M=Co, Mn) spin helices","The properties of two molecular-based magnetic helices, composed of 3$d$
+metal Co and Mn ions bridged by Nitronyl Nitroxide radicals, are investigated
+by density functional calculations. Their peculiar and distinctive magnetic
+behavior is here elucidated by a thorough description of their magnetic,
+electronic, and anisotropy properties. Metal ions are antiferromagnetically
+coupled with the radicals, leading to a ferrimagnetically ordered ground state.
+A strong metal-radical exchange coupling is found, about 44 meV and 48 meV for
+Co- and Mn-helices, respectively. The latter have also relevant
+next-nearest-neighbor Mn-Mn antiferromagnetic interactions (of $\sim$ 6 meV).
+Co-sites are characterized by non-collinear uniaxial anisotropies, whereas
+Mn-sites are rather isotropic. A key result pertains to the Co-helix: the
+microscopic picture resulting from density-functional calculations allows us to
+propose a spin Hamiltonian of increased complexity with respect to the commonly
+employed Ising Hamiltonian, suitable for the study of finite-temperature
+behavior, and that seems to clarify the puzzling scenario of multiple
+characteristic energy scales observed in experiments.",1503.00292v1
+2015-03-06,Observation of Optical Solitons and Abnormal Modulation Instability in Liquid Crystals with Negative Dielectric Anisotropy,"We investigate theoretically and experimentally the optical beam propagation
+in the nematic liquid crystal with negative dielectric anisotropy, which is
+aligned homeotropically in a $80\mu m$-thickness planar cell in the presence of
+an externally voltage. It is predicted that the nonlocal nonlinearity of liquid
+crystal undergo an oscillatory response function with a negative nonlinear
+refractive index coefficient. We found that the oscillatory nonlocal
+nonlinearity can support stable bright solitons, which are observed in
+experiment. We also found that abnormal modulation instability occurs with
+infinity gain coefficient at a fixed spatial frequency, which is no depend on
+the beam intensity. We observed the modulation instability in the liquid
+crystal at a very low intensity ($0.26W/cm^2$), and the maximum gain frequency
+were found kept unchange when beam power changes over 2-3 orders of magnitude.",1503.01953v1
+2015-03-13,Magnetic interactions in iron superconductors: A review,"High temperature superconductivity in iron pnictides and chalcogenides
+emerges when a magnetic phase is suppressed. The multi-orbital character and
+the strength of correlations underlie this complex phenomenology, involving
+magnetic softness and anisotropies, with Hund's coupling playing an important
+role. We review here the different theoretical approaches used to describe the
+magnetic interactions in these systems. We show that taking into account the
+orbital degree of freedom allows us to unify in a single phase diagram the main
+mechanisms proposed to explain the (\pi,0) order in iron pnictides: the
+nesting-driven, the exchange between localized spins, and the Hund induced
+magnetic state with orbital differentiation. Comparison of theoretical
+estimates and experimental results helps locate the Fe superconductors in the
+phase diagram. In addition, orbital physics is crucial to address the magnetic
+softness, the doping dependent properties, and the anisotropies.",1503.04223v2
+2015-03-19,Anomalous magnetization of $S$=2 ferromagnetic-antiferromagnetic alternating chain with Ising anisotropy,"We present the first experimental realization of an $S=2$
+ferromagnetic-antiferromagnetic (F-AF) alternating chain in a new Mn-verdazyl
+complex [Mn(hfac)$_2$]$\cdot$($o$-Py-V)
+[hfac=1,1,1,5,5,5-hexafluoroacetylacetonate;
+$o$-Py-V=3-(2-pyridyl)-1,5-diphenylverdazyl]. Through the $ab$ $initio$
+molecular orbital calculation, magnetization, and ESR measurements, this
+compound is confirmed to form an $S=2$ F-AF alternating chain with Ising
+anisotropy below about 100 K. Furthermore, we find an anomalous change in
+magnetization at 1/4 of the saturation value, which is probably a manifestation
+of the quantum nature of the system.",1503.05633v1
+2015-03-23,Quantum phase transition in the spin-anisotropic quantum spherical model,"Motivated by an analogy with the spin anisotropies in the quantum XY chain
+and its reformulation in terms of spin-less Majorana fermions, its bosonic
+analogue, the spin-anisotropic quantum spherical model, is introduced. The
+exact solution of the model permits to analyse the influence of the
+spin-anisotropy on the phase diagram and the universality of the critical
+behaviour in a new way, since the interactions of the quantum spins and their
+conjugate momenta create new effects. At zero temperature, a quantum critical
+line is found, which is in the same universality class as the thermal phase
+transition in the classical spherical model in $d+1$ dimensions. The location
+of this quantum critical line shows a re-entrant quantum phase transition for
+dimensions $1<d\lesssim 2.065$.",1503.06713v2
+2015-03-30,Dynamical Evolution of Anisotropic Response in Black Phosphorus under Ultrafast Photoexcitation,"Black phosphorus has recently emerged as a promising material for high
+performance electronic and optoelectronic device for its high mobility, tunable
+mid-infrared bandgap and anisotropic electronic properties. Dynamical evolution
+of photo excited carriers and its induced change of transient electronic
+properties are critical for materials' high field performance, but remains to
+be explored for black phosphorus. In this work, we perform angle resolved
+transient reflection spectroscopy to study the dynamical evolution of
+anisotropic properties of black phosphorus under photo excitation. We find that
+the anisotropy of reflectivity is enhanced in the pump induced
+quasi-equilibrium state, suggesting an extraordinary enhancement of the
+anisotropy in dynamical conductivity in hot carrier dominated regime. These
+results raise enormous possibilities of creating high field, angle sensitive
+electronic, optoelectronic and remote sensing devices exploiting the dynamical
+electronic anisotropic with black phosphorus.",1503.08524v1
+2015-04-03,Ising exchange interaction in lanthanides and actinides,"The Ising exchange interaction is a limiting case of strong exchange
+anisotropy and represents a key property of many magnetic materials. Here we
+find necessary and sufficient conditions to achieve Ising exchange interaction
+for metal sites with unquenched orbital moments. Contrary to current views, the
+rules established here narrow much the range of lanthanide and actinide ions
+which can exhibit Ising exchange interaction. It is shown that the arising
+Ising interaction can be of two distinct types: (i) coaxial, with magnetic
+moments directed along the anisotropy axes on the metal sites and (ii)
+non-coaxial, with arbitrary orientation of one of magnetic moments. These
+findings will contribute to purposeful design of lanthanide and actinide based
+materials.",1504.00784v3
+2015-04-08,Proximity effect between a topological insulator and a magnetic insulator with large perpendicular anisotropy,"We report that thin films of a prototype topological insulator,
+Bi$_{2}$Se$_{3}$, can be epitaxially grown onto the (0001) surface of
+BaFe$_{12}$O$_{19}$(BaM), a magnetic insulator with high Curie temperature and
+large perpendicular anisotropy. In the Bi$_2$Se$_3$ thin films grown on
+non-magnetic substrates, classic weak antilocalization (WAL) is manifested as
+cusp-shaped positive magnetoresistance (MR) in perpendicular magnetic fields
+and parabola-shaped positive MR in parallel fields, whereas in
+Bi$_{2}$Se$_{3}$/BaM heterostructures the low field MR is parabola-shaped,
+which is positive in perpendicular fields and negative in parallel fields. The
+magnetic field and temperature dependence of the MR is explained as a
+consequence of the suppression of WAL due to strong magnetic interactions at
+the Bi$_{2}$Se$_{3}$/BaM interface.",1504.01922v1
+2015-04-09,Disentangling inertial waves from eddy turbulence in a forced rotating turbulence experiment,"We present a spatio-temporal analysis of a statistically stationary rotating
+turbulence experiment, aiming to extract a signature of inertial waves, and to
+determine the scales and frequencies at which they can be detected. The
+analysis uses two-point spatial correlations of the temporal Fourier transform
+of velocity fields obtained from time-resolved stereoscopic particle image
+velocimetry measurements in the rotating frame. We quantify the degree of
+anisotropy of turbulence as a function of frequency and spatial scale. We show
+that this space-time-dependent anisotropy is well described by the dispersion
+relation of linear inertial waves at large scale, while smaller scales are
+dominated by the sweeping of the waves by fluid motion at larger scales. This
+sweeping effect is mostly due to the low-frequency quasi-two-dimensional
+component of the turbulent flow, a prominent feature of our experiment which is
+not accounted for by wave turbulence theory. These results question the
+relevance of this theory for rotating turbulence at the moderate Rossby numbers
+accessible in laboratory experiments, which are relevant to most geophysical
+and astrophysical flows.",1504.02224v1
+2015-04-14,Testing the isotropy of the Universe by using the JLA compilation of type-Ia supernovae,"We probe the possible anisotropy of the Universe by using the JLA compilation
+of type-Ia supernovae. We apply the Markov Chain Monte Carlo (MCMC) method to
+constrain the amplitude and direction of anisotropy in three cosmological
+models. For the dipole-modulated $\Lambda$CDM model, the anisotropic amplitude
+is consistent with zero at $68\%$ C.L., and has an upper bound
+$A_D<1.98\times10^{-3}$ at $95\%$ C.L. Regardless of much larger uncertainty,
+we find the dipole direction of JLA is amazingly opposite to that of Union2.
+Similar results are found for the dipole-modulated $w$CDM and CPL models. Thus,
+the Universe is still well consistent with the isotropy according to the JLA
+compilation.",1504.03428v2
+2015-04-15,The Anisotropic Line Correlation Function as a Probe of Anisotropies in Galaxy Surveys,"We propose an anisotropic generalisation of the line correlation function
+(ALCF) to separate and quantify phase information in the large-scale structure
+of galaxies. The line correlation function probes the strictly non-linear
+regime of structure formation and since phase information drops out of the
+power spectrum, the line correlation function provides a complementary tool to
+commonly used techniques based on two-point statistics. Furthermore, it is
+independent of linear bias as well as the Gaussian variance on the modulus of
+the density field and thus may also prove to be advantageous compared to the
+bispectrum or similar higher-order statistics for certain cases. For future
+applications it is vital, though, to be able to account for observational
+effects that cause anisotropies in the distribution of galaxies. Based on a
+number of numerical studies, we find that our ALCF is well suited to accomplish
+this task and we demonstrate how the Alcock-Paczynski effect and kinematical
+redshift-space distortions can in principle be measured via the ALCF.",1504.04036v1
+2015-04-21,Uniaxial anisotropy and low-temperature antiferromagnetism of Mn2BO4 single crystal,"The Mn2BO4 single crystals have been grown using the flux technique. The
+careful study crystal structure and magnetic properties have been carried out.
+The antiferromagnet transition at TN = 26 K has been traced through the dc
+magnetization and specific heat temperature dependences. The magnetic uniaxial
+anisotropy has been detected with easy axis of magnetization lying in ab-plane.
+A reduction of the effective magnetic moment value is assigned to the
+non-quenched orbital moment of Jahn-Teller Mn3+ ions. Based on the
+superexchange interactions calculations the magnetic behavior is discussed.",1504.05870v1
+2015-04-27,Two types of nematicity in the phase diagram of the cuprate superconductor YBa$_2$Cu$_3$O$_y$,"Nematicity has emerged as a key feature of cuprate superconductors, but its
+link to other fundamental properties such as superconductivity, charge order
+and the pseudogap remains unclear. Here we use measurements of transport
+anisotropy in YBa$_2$Cu$_3$O$_y$ to distinguish two types of nematicity. The
+first is associated with short-range charge-density-wave modulations in a
+doping region near $p = 0.12$. It is detected in the Nernst coefficient, but
+not in the resistivity. The second type prevails at lower doping, where there
+are spin modulations but no charge modulations. In this case, the onset of
+in-plane anisotropy - detected in both the Nernst coefficient and the
+resistivity - follows a line in the temperature-doping phase diagram that
+tracks the pseudogap energy. We discuss two possible scenarios for the latter
+nematicity.",1504.06972v3
+2015-04-27,FeCoCp3 Molecular Magnets as Spin Filters,"Metallorganic molecules have been proposed as excellent spin filters in
+molecular spintronics because of the large spin-polarization of their
+electronic structure. However, most of the studies involving spin transport,
+have disregarded fundamental aspects such as the magnetic anisotropy of the
+molecule and the excitation of spin-flip processes during electron transport.
+Here, we study a molecule containing a Co and an Fe atoms stacked between three
+cyclopentadienyl rings that presents a large magnetic anisotropy and a S=1.
+These figures are superior to other molecules with the same transition metal,
+and improves the spin-filtering capacities of the molecule. Non-equilibrium
+Green's functions calculations based on density functional theory predict
+excellent spin-filtering properties both in tunnel and contact transport
+regimes. However, exciting the first magnetic state drastically reduces the
+current's spin polarization. Furthermore, a difference of temperature between
+electrodes leads to strong thermoelectric effects that also suppress spin
+polarization. Our study shows that in-principle good molecular candidates for
+spintronics need to be confronted with inelastic and thermoelectric effects.",1504.07282v1
+2015-04-28,Monte-Carlo study of anisotropic scaling generated by disorder,"We analyze the critical properties of the three-dimensional Ising model with
+linear parallel extended defects. Such a form of disorder produces two distinct
+correlation lengths, a parallel correlation length $\xi_\parallel$ in the
+direction along defects, and a perpendicular correlation length $\xi_\perp$ in
+the direction perpendicular to the lines. Both $\xi_\parallel$ and $\xi_\perp$
+diverge algebraically in the vicinity of the critical point, but the
+corresponding critical exponents $\nu_\parallel$ and $\nu_\perp$ take different
+values. This property is specific for anisotropic scaling and the ratio
+$\nu_\parallel/\nu_\perp$ defines the anisotropy exponent $\theta$. Estimates
+of quantitative characteristics of the critical behaviour for such systems were
+only obtained up to now within the renormalization group approach. We report a
+study of the anisotropic scaling in this system via Monte Carlo simulation of
+the three-dimensional system with Ising spins and non-magnetic impurities
+arranged into randomly distributed parallel lines. Several independent
+estimates for the anisotropy exponent $\theta$ of the system are obtained, as
+well as an estimate of the susceptibility exponent $\gamma$. Our results
+corroborate the renormalization group predictions obtained earlier.",1504.07588v1
+2015-05-09,Quantum Engineering of Spin and Anisotropy in Magnetic Molecular Junctions,"Single molecule magnets and single spin centers can be individually addressed
+when coupled to contacts forming an electrical junction. In order to control
+and engineer the magnetism of quantum devices, it is necessary to quantify how
+the structural and chemical environment of the junction affects the spin
+center. Metrics such as coordination number or symmetry provide a simple method
+to quantify the local environment, but neglect the many-body interactions of an
+impurity spin when coupled to contacts. Here, we utilize a highly corrugated
+hexagonal boron nitride (h-BN) monolayer to mediate the coupling between a
+cobalt spin in CoHx (x=1,2) complexes and the metal contact. While the hydrogen
+atoms control the total effective spin, the corrugation is found to smoothly
+tune the Kondo exchange interaction between the spin and the underlying metal.
+Using scanning tunneling microscopy and spectroscopy together with numerical
+simulations, we quantitatively demonstrate how the Kondo exchange interaction
+mimics chemical tailoring and changes the magnetic anisotropy.",1505.02277v1
+2015-05-12,Wave mechanics in media pinned at Bravais lattice points,"The propagation of waves through microstructured media with periodically
+arranged inclusions has applications in many areas of physics and engineering,
+stretching from photonic crystals through to seismic metamaterials. In the
+high-frequency regime, modelling such behaviour is complicated by multiple
+scattering of the resulting short waves between the inclusions. Our aim is to
+develop an asymptotic theory for modelling systems with arbitrarily-shaped
+inclusions located on general Bravais lattices. We then consider the limit of
+point-like inclusions, the advantage being that exact solutions can be obtained
+using Fourier methods, and go on to derive effective medium equations using
+asymptotic analysis. This approach allows us to explore the underlying reasons
+for dynamic anisotropy, localisation of waves, and other properties typical of
+such systems, and in particular their dependence upon geometry. Solutions of
+the effective medium equations are compared with the exact solutions, shedding
+further light on the underlying physics. We focus on examples that exhibit
+dynamic anisotropy as these demonstrate the capability of the asymptotic theory
+to pick up detailed qualitative and quantitative features.",1505.02889v1
+2015-05-20,Anisotropy Reversal of the Upper Critical Field at Low Temperatures and Spin-Locked Superconductivity in K2Cr3As3,"We report the first measurements of the anisotropic upper critical field
+$H_{c2}(T)$ for K$_{2}$Cr$_{3}$As$_{3}$ single crystals up to 60 T and $T >
+0.6$ K. Our results show that the upper critical field parallel to the Cr
+chains, $H_{c2}^\parallel (T)$, exhibits a paramagnetically-limited behavior,
+whereas the shape of the $H_{c2}^\perp (T)$ curve (perpendicular to the Cr
+chains) has no evidence of paramagnetic effects. As a result, the curves
+$H_{c2}^\perp (T)$ and $H_{c2}^\parallel(T)$ cross at $T\approx 4$ K, so that
+the anisotropy parameter $\gamma_H(T)=H_{c2}^\perp/H_{c2}^\parallel (T)$
+increases from $\gamma_H(T_c)\approx 0.35$ near $T_c$ to $\gamma_H(0)\approx
+1.7$ at 0.6 K. This behavior of $H_{c2}^\|(T)$ is inconsistent with triplet
+superconductivity but suggests a form of singlet superconductivity with the
+electron spins locked onto the direction of Cr chains.",1505.05547v1
+2015-05-21,"Competition of magneto-dipole, anisotropy and exchange interactions in composite multiferroics","We study the competition of magneto-dipole, anisotropy and exchange
+interactions in composite three dimensional multiferroics. Using Monte Carlo
+simulations we show that magneto-dipole interaction does not suppress the
+ferromagnetic state caused by the interaction of the ferroelectric matrix and
+magnetic subsystem. However, the presence of magneto-dipole interaction
+influences the order-disorder transition: depending on the strength of
+magneto-dipole interaction the transition from the ferromagnetic to the
+superparamagnetic state is accompanied either by creation of vortices or
+domains of opposite magnetization. We show that the temperature hysteresis loop
+occurs due to non-monotonic behavior of exchange interaction versus
+temperature. The origin of this hysteresis is related to the presence of stable
+magnetic domains which are robust against thermal fluctuations.",1505.05605v1
+2015-05-27,Torque magnetometry study of magnetically ordered state and spin reorientation in the quasi-one-dimensional $S=1/2$ Heisenberg antiferromagnet CuSb$_2$O$_6$,"We present an experimental study of macroscopic and microscopic magnetic
+anisotropy of a spin tetramer system \cso using torque magnetometry and ESR
+spectroscopy. Large rotation of macroscopic magnetic axes with temperature
+observed from torque magnetometry agrees reasonably well with the rotation of
+the $\mathbf{g}$ tensor above $T \gtrsim 50$~K. Below 50~K, the $\mathbf{g}$
+tensor is temperature independent, while macroscopic magnetic axes continue to
+rotate. Additionally, the susceptibility anisotropy has a temperature
+dependence which cannot be reconciled with the isotropic Heisenberg model of
+interactions between spins. ESR linewidth analysis shows that anisotropic
+exchange interaction must be present in \csos. These findings strongly support
+the presence of anisotropic exchange interactions in the Hamiltonian of the
+studied system. Below $T_N=8$~K, the system enters a long - range
+antiferromagnetically ordered state with easy axis along the $<\bar{1} 0 1>^*$
+direction. Small but significant rotation of magnetic axes is also observed in
+the antiferromagnetically ordered state suggesting strong spin-lattice coupling
+in this system.",1505.07405v1
+2015-05-28,Incommensurate spin density wave at a ferromagnetic quantum critical point in a three-dimensional parabolic semimetal,"We explore the ferromagnetic quantum critical point in a three-dimensional
+semimetallic system with upward- and downward-dispersing bands touching at the
+Fermi level. Evaluating the static spin susceptibility to leading order in the
+coupling between the fermions and the fluctuating ferromagnetic order
+parameter, we find that the ferromagnetic quantum critical point is masked by
+an incommensurate, longitudinal spin density wave phase. We first analyze an
+idealized model which, despite having strong spin-orbit coupling, still
+possesses O(3) rotational symmetry generated by the total angular momentum
+operator. In this case, the direction of the incommensurate spin density wave
+propagation can point anywhere, while the magnetic moment is aligned along the
+direction of propagation. Including symmetry-allowed anisotropies in the
+fermion dispersion and the coupling to the order parameter field, however, the
+ordering wavevector instead breaks a discrete symmetry and aligns along either
+the [111] or [100] direction, depending on the signs and magnitudes of these
+two types of anisotropy.",1505.07685v1
+2015-05-30,Large increase of the anisotropy factor in the overdoped region of Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$ as probed by fluctuation spectroscopy,"We study the diamagnetism induced by thermal fluctuations above the
+superconducting transition of the iron pnictide Ba(Fe$_{1-x}$Ni$_x$)$_2$As$_2$
+with different doping levels. The measurements are performed with magnetic
+fields up to 7 T applied in the two main crystal directions. These data provide
+double information: first, they confirm at a quantitative level the
+applicability to these materials of a 3D-anisotropic Ginzburg-Landau approach
+valid in the finite field regime. Then, they allow to determine the
+doping-level dependence of the in-plane coherence length and of the
+superconducting anisotropy factor, $\gamma$. Our results provide a stringent
+confirmation of the large increase of $\gamma$ with the doping level, as
+recently proposed from magnetoresistivity measurements. The implications of the
+applicability of the model used to a multiband superconductor are discussed.",1506.00170v1
+2015-06-04,High Curie temperature and perpendicular magnetic anisotropy in homoepitaxial InMnAs films,"We have prepared the dilute magnetic semiconductor (DMS) InMnAs with
+different Mn concentrations by ion implantation and pulsed laser melting. The
+Curie temperature of the In1-xMnxAs epilayer depends on the Mn concentration x,
+reaching 82 K for x=0.105. The substitution of Mn ions at the Indium sites
+induces a compressive strain perpendicular to the InMnAs layer and a tensile
+strain along the in-plane direction. This gives rise to a large perpendicular
+magnetic anisotropy, which is often needed for the demonstration of electrical
+control of magnetization and for spin-transfer-torque induced magnetization
+reversal.",1506.01537v1
+2015-06-05,The Shear Viscosity in Anisotropic Phases,"We construct anisotropic black brane solutions and analyse the behaviour of
+some of their metric perturbations. These solutions correspond to field theory
+duals in which rotational symmetry is broken due an externally applied,
+spatially constant, force. We find, in several examples, that when the
+anisotropy is sufficiently big compared to the temperature, some components of
+the viscosity tensor can become very small in units of the entropy density,
+parametrically violating the KSS bound. We obtain an expression relating these
+components of the viscosity, in units of the entropy density, to a ratio of
+metric components at the horizon of the black brane. This relation is generally
+valid, as long as the forcing function is translationally invariant, and it
+directly connects the parametric violation of the bound to the anisotropy in
+the metric at the horizon. Our results suggest the possibility that such small
+components of the viscosity tensor might also arise in anisotropic strongly
+coupled fluids found in nature.",1506.01899v3
+2015-06-09,On the Stability of (M theory) Stars against Collapse : Role of Anisotropic Pressures,"Unitarity of evolution in gravitational collapses implies existence of
+macroscopic stable horizonless objects. With such objects in mind, we study the
+effects of anisotropy of pressures on the stability of stars. We consider stars
+in four or higher dimensions and also stars in M theory made up of
+(intersecting) branes. Taking the stars to be static, spherically symmetric and
+the equations of state to be linear, we study `singular solutions' and the
+asymptotic perturbations around them. Oscillatory perturbations are likely to
+imply instability. We find that non oscillatory perturbations, which may imply
+stability, are possible if an appropriate amount of anisotropy is present. This
+result suggests that it may be possible to have stable horizonless objects in
+four or any higher dimensions, and that anisotropic pressures may play a
+crucial role in ensuring their stability.",1506.02769v3
+2015-06-09,Unitary evolution for a quantum Kantowski-Sachs cosmology,"It is shown that like Bianchi I, V and IX models, a Kantowski-Sachs
+cosmological model also allows a unitary evolution on quantization. It has also
+been shown that this unitarity is not at the expense of the anisotropy.
+Non-unitarity, if there is any, cannot escape notice in this as the evolution
+is studied against a properly oriented time parameter fixed by the evolution of
+the fluid. Furthermore, we have constructed a wave-packet by superposing
+different energy eigenstates, thereby establishing unitarity in a non-trivial
+way, which is a stronger result than an energy eigenstate trivially giving time
+independent probability density. For $\alpha\neq1$, we have proved that the
+Hamiltonian upon suitable operator ordering admits a self-adjoint extension
+under reasonable assumption, using a standard theorem. This consolidates the
+recently shown fact that the problem of non-unitarity cannot be a generic
+problem of anisotropy.",1506.02770v1
+2015-06-17,"Temperature-dependent thermal conductivity and diffusivity of a Mg-doped insulating $β$-$\mathrm{Ga_2O_3}$ single crystal along [100], [010] and [001]","The monoclinic crystal structure of $\beta$-$\mathrm{Ga_2O_3}$ leads to
+significant anisotropy of the thermal properties. The 2$\omega$-method is used
+to measure the thermal diffusivity $D$ in [010] and [001] direction
+respectively and to determine the thermal conductivity values $\lambda$ of the
+[100], [010] and [001] direction from the same insulating Mg doped
+$\beta$-$\mathrm{Ga_2O_3}$ single crystal. We detect a temperature independent
+anisotropy factor of both the thermal diffusivity and conductivity values of
+$D_{[010]}/D_{[001]}=\lambda_{[010]}/\lambda_{[001]}=1.4\pm 0.1$. The
+temperature-dependence is in accord with phonon-phonon-Umklapp scattering
+processes from 300 K down to 150 K. Below 150 K point-defect-scattering lowers
+the estimated phonon-phonon-Umklapp-scattering values.",1506.05294v3
+2015-06-23,Anisotropic matching principle for the hydrodynamics expansion,"Following the recent success of anisotropic hydrodynamics we propose a new,
+general prescription for the hydrodynamics expansion around an anisotropic
+background. The anisotropic distribution is fixing exactly the complete
+energy-momentum tensor, just like the effective temperature is fixing the
+proper energy density in the ordinary expansion around local equilibrium. This
+means that momen- tum anisotropies are already included at the leading order,
+allowing for large pressure anisotropies without the need of a next to leading
+order treatment. The first moment of the Boltzmann equation (local
+four-momentum conservation) provides the time evolution of the proper energy
+density and the four velocity. Differently from previous prescriptions, the
+dynamic equations for the pressure corrections are not derived from the zeroth
+or second moment of the Boltzmann equation, but they are taken directly from
+the exact evolution given by the Boltzmann equation. We check the effec-
+tiveness of this new approach by matching with the exact solution of the
+Boltzmann equation in the Bjorken limit with the collisional kernel treated in
+relaxation time approximation, finding an unprecedented agreement.",1506.07164v1
+2015-06-23,A new phase for the anisotropic N=4 super Yang-Mills plasma,"Black hole solutions of type IIB supergravity have been previously
+constructed that describe the N=4 supersymmetric Yang-Mills plasma with an
+anisotropic spatial deformation. The zero temperature limit of these black
+holes approach a Lifshitz-like scaling solution in the infrared. We show that
+these black holes become unstable at low temperature and we construct a new
+class of black hole solutions which are thermodynamically preferred. The phase
+transition is third order and incorporates a spontaneous breaking of the
+$SO(6)$ global symmetry down to $SO(4)\times SO(2)$. The critical exponents for
+the phase transition are given by $(\alpha,\beta,\gamma,\delta)=(-1,1,1,2)$
+which differ from the standard mean-field exponents usually seen in holography.
+At low temperatures the black holes approach a novel kind of scaling behaviour
+in the far IR with spatial anisotropy and hyperscaling violation. We show that
+the new ground states are thermal insulators in the direction of the
+anisotropy.",1506.07176v2
+2015-06-24,C-axis electrical resistivity of PrO$_{1-a}$F$_a$BiS$_2$ single crystals,"The high anisotropy in RO1-aFaBiS2 (R denotes a rare-earth element)
+superconductors demonstrates their potential use as intrinsic Josephson
+junctions, considering the weak coupling among BiS2-PrO(F)-BiS2
+(superconducting-normal-superconducting) layers along the c-axis. We grew
+PrO1-aFaBiS2 single crystals using CsCl/KCl flux. The superconducting
+anisotropies of the grown single crystals were estimated to be approximately
+40-50 from the effective mass model. The c-axis transport properties were
+characterized using single-crystal s-shaped intrinsic Josephson junctions with
+a focused ion beam. Along the c-axis, the crystals showed zero resistivity at
+2.7 K and a critical current density of 1.33*10^3 A/cm2 at 2.0 K. The
+current-voltage curve along the c-axis displayed hysteresis. The c-axis
+transport measurements under a magnetic field parallel to the ab-plane revealed
+a ""lock-in"" state due to the Josephson vortex flow, indicating that BiS2
+superconductors are promising candidates for intrinsic Josephson junctions.",1506.07231v1
+2015-06-25,Heavy quarkonia in strong magnetic fields,"We investigate the influence of a homogeneus and constant strong external
+magnetic field on the heavy-meson spectrum. Quarkonium states $c\bar{c}$ and
+$b\bar{b}$ are described within a non-relativistic framework and by means of a
+suitable potential model based on the Cornell parametrization. In particular,
+in this work we propose a model which takes into account the possible
+anisotropies emerging at the level of the static quark-antiquark potential, as
+observed in recent lattice studies. The investigation is perfomed both with and
+without taking into account the anisotropy of the static potential, in order to
+better clarify its effects",1506.07890v2
+2015-06-26,Shapes for maximal coverage for two-dimensional random sequential adsorption,"The random sequential adsorption of various particle shapes is studied in
+order to determine the influence of particle anisotropy on the saturated random
+packing. For all tested particles there is an optimal level of anisotropy which
+maximizes the saturated packing fraction. It is found that a concave shape
+derived from a dimer of disks gives a packing fraction of 0.5833, which is
+comparable to the maximum packing fraction of ellipsoids and spherocylinders
+and higher than any other studied shape. Discussion why this shape is so
+beneficial for random sequential adsorption is given.",1506.08164v2
+2015-06-27,K*0(892) and phi(1020) resonance production at RHIC,"The measurement of resonance production in ultrarelativistic heavy-ion
+collisions provides a glimpse of the hadronic medium properties and its
+evolution at different stages. Resonances decaying into hadrons are used to
+estimate the time span and hadronic interaction cross section in the hadronic
+phase between chemical and kinetic freeze-out. Specifically, the comparison of
+K*0(892) and phi(1020) resonances is interesting as the lifetimes of these
+particles differ by about a factor of 10. Moreover, the nuclear modification
+factor and azimuthal anisotropy measurements of mesonic resonances, which
+measure parton energy loss in medium and reflect partonic collectivity, can
+also probe particle-species and mass ordering.
+  The K*0(892) and phi(1020) resonance production at mid-rapidity (|y|<0.5),
+measured in high energy (Au+Au, Cu+Cu, d+Au and p+p) collisions at RHIC with
+STAR experiment, reconstructed by their hadronic decay in Kpi and KK,
+respectively, are discussed. Mesons' spectra, yields, mean transverse momentum,
+nuclear modification factor, and azimuthal anisotropy are discussed as a
+function of centrality and collision energy.",1506.08289v1
+2015-06-30,Discrete Solitons and Vortices in Anisotropic Hexagonal and Honeycomb Lattices,"In the present work, we consider the self-focusing discrete nonlinear
+Schrodinger equation on hexagonal and honeycomb lattice geometries. Our
+emphasis is on the study of the effects of anisotropy, motivated by the
+tunability afforded in recent optical and atomic physics experiments. We find
+that important classes of solutions, such as the so-called discrete vortices,
+undergo destabilizing bifurcations as the relevant anisotropy control parameter
+is varied. We quantify these bifurcations by means of explicit analytical
+calculations of the solutions, as well as of their spectral linearization
+eigenvalues. Finally, we corroborate the relevant stability picture through
+direct numerical computations. In the latter, we observe the prototypical
+manifestation of these instabilities to be the spontaneous rearrangement of the
+solution, for larger values of the coupling, into localized waveforms typically
+centered over fewer sites than the original unstable structure. For weak
+coupling, the instability appears to result in a robust breathing of the
+relevant waveforms.",1506.08945v1
+2015-07-01,Fading Features Found in the Kinematics of the Far-Reaching Milky Way Stellar Halo,"We test the long-term kinematical stability of a Galactic stellar halo model,
+due to Kafle, et al. (2012), who study the kinematics of approximately 5000
+blue horizontal branch (BHB) stars in the Sloan Digital Sky Survey (SDSS). The
+velocity dispersion $\sigma$ and anisotropy parameter $\beta$ of the stars have
+been determined as functions of Galactocentric radius, over the range
+$6<R_\mathrm{GC} < 25$ kpc, and show a strong dip in the anisotropy profile at
+$R_\mathrm{GC}\sim17$ kpc. By directly integrating orbits of particles in a 3-D
+model of the Galactic potential with these characteristics, we show that the
+$\sigma$ and $\beta$ profiles quickly evolve on a time scale of a
+$\mathrm{few}\times10$ Myr whereas the density $\rho$ profile remains largely
+unaffected. We suggest that the feature is therefore transient. The origin of
+such features in the Galactic halo remains unclear.",1507.00351v1
+2015-07-02,Microscale locomotion in a nematic liquid crystal,"Microorganisms often encounter anisotropy, for example in mucus and biofilms.
+We study how anisotropy and elasticity of the ambient fluid affects the speed
+of a swimming microorganism with a prescribed stroke. Motivated by recent
+experiments on swimming bacteria in anisotropic environments, we extend a
+classical model for swimming microorganisms, the Taylor swimming sheet,
+actuated either by transverse or longitudinal traveling waves in a
+three-dimensional nematic liquid crystal without twist. We calculate the
+swimming speed and entrained volumetric flux as a function of the swimmer's
+stroke properties as well as the elastic and rheological properties of the
+liquid crystal. The behavior is quantitatively and qualitatively
+well-approximated by a hexatic liquid crystal except in the cases of small
+Ericksen number and in a nematic fluid with tumbling parameter near the
+transition to a flow-aligning nematic, where anisotropic effects dominate. We
+also propose a novel method of swimming or pumping in a nematic fluid by
+passing a traveling wave of director oscillation along a rigid wall.",1507.00776v2
+2015-07-03,Signal Improvement and Contrast Enhancement in Magnetic Resonance Imaging,"This thesis reports advances in magnetic resonance imaging (MRI), with the
+ultimate goal of improving signal and contrast in biomedical applications. More
+specifically, novel MRI pulse sequences have been designed to characterize
+microstructure, enhance signal and contrast in tissue, and image functional
+processes. In this thesis, rat brain and red bone marrow images are acquired
+using iMQCs (intermolecular multiple quantum coherences) between intermediate
+separated spins. As an important application, iMQCs images in different
+directions can be used for anisotropy mapping and tissue microstructure
+analysis. At the same time, the simulations prove that the dipolar field from
+the overall shape only has small contributions to the experimental iMQC signal.
+Besides magnitude of iMQCs, phase of iMQCs should be studied as well. The phase
+anisotropy maps built by our method can clearly show susceptibility information
+in rat brain. It may provide meaningful diagnostic information. To deeply study
+susceptibility, the modified-crazed sequence is developed. Combining phase data
+of modified-crazed images and phase data of iMQCs images is very promising to
+construct microstructure maps. Obviously, the phase image in all above
+techniques needs to be highly-contrasted and clear. To achieve the goal,
+algorithm tools from Susceptibility-Weighted Imaging (SWI) and Susceptibility
+Tensor Imaging (STI) stands out superb useful and creative in our system.",1507.01035v1
+2015-07-09,Equilibrium structure and fluctuations of suspensions of colloidal dumbbells,"We investigate the structure and equilibrium linear-response dynamics of
+suspensions of hard colloidal dumbbells using Brownian Dynamics computer
+simulations. The focus lies on the dense fluid and plastic crystal states of
+the colloids with investigated aspect (elongation-to-diameter) ratios varying
+from the hard sphere limit up to 0.39, which is roughly the stability limit of
+the plastic crystal phase. We find expected structural changes with larger
+elongation with respect to the hard sphere reference case and very localized
+orientational correlations, typically just involving next-neighbor couplings.
+These relatively weak correlations are also reflected in only minor effects on
+the translational and rotational diffusion coefficients for most of the
+investigated elongations. However, the linear response shear viscosity exhibits
+a dramatic increase at high packing fractions ($\phi\gtrsim 0.5$) beyond a
+critical anisotropy factor of about $L^* \simeq 0.15$ which is surprising in
+view of the relatively weak changes found before on the level of colloidal
+self-dynamics. We suspect that even for the small investigated anisotropies,
+newly occurring, collective rotational-translational couplings must be made
+responsible for the slow time scales appearing in the plastic crystal.",1507.02533v1
+2015-05-29,Anisotropic dark energy model with a hybrid scale factor,"Anisotropic dark energy model with dynamic pressure anisotropies along
+different spatial directions is constructed at the backdrop of a spatially
+homogeneous diagonal Bianchi type $V$ $(BV)$ space-time in the framework of
+General Relativity. A time varying deceleration parameter generating a hybrid
+scale factor is considered to simulate a cosmic transition from early
+deceleration to late time acceleration. We found that the pressure anisotropies
+along the $y-$ and $z-$ axes evolve dynamically and continue along with the
+cosmic expansion without being subsided even at late times. The anisotropic
+pressure along the $x-$axis becomes equal to the mean fluid pressure. At a late
+phase of cosmic evolution, the model enters into a phantom region. From a state
+finder diagnosis, it is found that the model overlaps with $\Lambda$CDM at late
+phase of cosmic time.",1507.03515v2
+2015-07-13,High temperature magnetic stabilization of cobalt nanoparticles by an antiferromagnetic proximity effect,"Thermal activation tends to destroy the magnetic stability of small magnetic
+nanoparticles, with crucial implications in ultra-high density recording among
+other applications. Here we demonstrate that low blocking temperature
+ferromagnetic (FM) Co nanoparticles (TB<70 K) become magnetically stable above
+400 K when embedded in a high N\'eel temperature antiferromagnetic (AFM) NiO
+matrix. The origin of this remarkable TB enhancement is due to a magnetic
+proximity effect between a thin CoO shell (with low N\'eel temperature, TN; and
+high anisotropy, KAFM) surrounding the Co nanoparticles and the NiO matrix
+(with high TN but low KAFM). This proximity effect yields an effective AFM with
+an apparent TN beyond that of bulk CoO, and an enhanced anisotropy compared to
+NiO. In turn, the Co core FM moment is stabilized against thermal fluctuations
+via core-shell exchange-bias coupling, leading to the observed TB increase.
+Mean-field calculations provide a semi-quantitative understanding of this
+magnetic- proximity stabilization mechanism.",1507.03608v1
+2015-07-16,Synchronization of particle motion in compressed two-dimensional plasma crystals,"The collective motion of dust particles during the mode-coupling induced
+melting of a two-dimensional plasma crystal is explored in molecular dynamics
+simulations. The crystal is compressed horizontally by an anisotropic
+confinement. This compression leads to an asymmetric triggering of the
+mode-coupling instability which is accompanied by alternating chains of
+in-phase and anti-phase oscillating particles. A new order parameter is
+proposed to quantify the synchronization with respect to different directions
+of the crystal. Depending on the orientation of the confinement anisotropy,
+mode-coupling instability and synchronized motion are observed in one or two
+directions. Notably, the synchronization is found to be direction-dependent.
+The good agreement with experiments suggests that the confinement anisotropy
+can be used to explain the observed synchronization process.",1507.04480v1
+2015-07-16,Global Existence of Weak Solutions for Compresssible Navier--Stokes Equations: Thermodynamically unstable pressure and anisotropic viscous stress tensor,"We prove global existence of appropriate weak solutions for the compressible
+Navier--Stokes equations for more general stress tensor than those covered by
+P.-L. Lions and E. Feireisl's theory. More precisely we focus on more general
+pressure laws which are not thermodynamically stable; we are also able to
+handle some anisotropy in the viscous stress tensor. To give answers to these
+two longstanding problems, we revisit the classical compactness theory on the
+density by obtaining precise quantitative regularity estimates: This requires a
+more precise analysis of the structure of the equations combined to a novel
+approach to the compactness of the continuity equation. These two cases open
+the theory to important physical applications, for instance to describe solar
+events (virial pressure law), geophysical flows (eddy viscosity) or biological
+situations (anisotropy).",1507.04629v2
+2015-07-16,Aspects of Anisotropic Fractional Quantum Hall Effect in Phosphorene,"We have analyzed the effects of the anisotropic energy bands of phosphorene
+on magnetoroton branches for electrons and holes in the two Landau levels close
+to the band edges. We have found that the fractional quantum Hall effect gap in
+the lowest (highest) Landau level in conduction (valance) band is slightly
+larger than that for conventional semiconductor systems and therefore
+experimentally observable. We also found that the magnetoroton mode for both
+electrons and holes consists of two branches with two minima due to the
+anisotropy. Additionally, we show that due to the anisotropy, there is a second
+mode with positive dispersion, well separated from the magnetoroton mode for
+small wave vectors. These novel features of the collective mode can be observed
+in resonant inelastic light scattering experiments.",1507.04709v1
+2015-07-17,Fluctuations in slope parameter in event-by-event hydrodynamics and momentum anisotropy in heavy ion collisions,"In event by event hydrodynamic model, we have simulated 30-40\% Au+Au
+collisions at RHIC and computed the slope parameter from the invariant pion
+distribution. In each event, the slope parameter fluctuates azimuthally.
+Fourier expansion coefficients $T_n$ for the slope parameter and the Fourier
+expansion coefficients $v_n$ for the azimuthal distribution $\frac{dN}{d\phi}$
+are found to be strongly correlated. Strong correlation between the two
+expansion coefficients suggests that in addition to azimuthal distribution,
+fluctuations in the slope parameter of the invariant distribution can as well
+be used to study the final state momentum anisotropy in relativistic energy
+heavy ion collisions. If measured experimentally, they can serve as additional
+constraint for hydrodynamical modeling.",1507.04898v1
+2015-07-20,Origin of the large anisotropic g-factor of holes in bismuth,"The ratio of the Zeeman splitting to the cyclotron energy ($M=\Delta E_{\rm
+Z}/\hbar \omega_{\rm c}$) for hole-like carriers in bismuth has been quantified
+with a great precision by many experiments performed during the past five
+decades. It exceeds 2 when the magnetic field is along the trigonal axis and
+vanishes in the perpendicular configuration. Theoretically, however, $M$ is
+expected to be isotropic and equal to unity in a two-band Dirac model. We argue
+that a solution to this half-a-century-old puzzle can be found by extending the
+$k\cdot p$ theory to multiple bands. Our model not only gives a quantitative
+account of magnitude and anisotropy of $M$ for hole-like carriers in bismuth,
+but also explains its contrasting evolution with antimony doping pressure, both
+probed by new experiments reported here. The present results have important
+implications for the magnitude and anisotropy of $M$ in other systems with
+strong spin-orbit coupling.",1507.05996v1
+2015-07-22,Magnetic anisotropy induced by crystal distortion in Ge1-xMn xTe/PbTe//KCl (001) ferromagnetic semiconductor layers,"Ferromagnetic resonance (FMR) study of magnetic anisotropy is presented for
+thin layers of IV-VI diluted magnetic semiconductor Ge1-xMn xTe with x=0.14
+grown by molecular beam epitaxy (MBE) on KCl (001) substrate with a thin PbTe
+buffer. Analysis of the angular dependence of the FMR resonant field reveals
+that an easy magnetization axis is located near to the normal to the layer
+plane and is controlled by two crystal distortions present in these
+rhombohedral Ge1-xMnxTe layers: the ferroelectric distortion with the relative
+shift of cation and anion sub-lattices along the [111] crystal direction and
+the biaxial in-plane, compressive strain due to thermal mismatch.",1507.06124v1
+2015-07-28,Effects of Dzyaloshinsky-Moriya Interaction on magnetism in Nanodisks,"We give a theoretical study on the magnetic properties of monolayer nanodisks
+with both Heisenberg exchange and Dzyaloshinsky-Moriya (DM) interactions. In
+particular, we survey the magnetic effects caused by anisotropy, external
+magnetic field, and disk size when DM interaction is present by means of a new
+quantum simulation method based on mean-field theory. This computational
+approach finds that uniaxial anisotropy and transverse magnetic field enhances
+the net magnetization as well as increases the transition temperature of the
+vortex phase while preserving the chiralities of the nanodisks. Whereas, when
+the strength of DM interaction is sufficiently strong for a given disk size,
+magnetic domains appear within the circularly bounded region, which vanish and
+gives in to a single vortex when a transverse magnetic field is applied. The
+latter confirms the magnetic skyrmions induced by the magnetic field as
+observed in the experiments.",1507.07715v1
+2015-07-31,Elastic Properties of FeC and FeN Martensites,"Single crystal elastic constants of bcc iron and bct FeC and FeN alloys,
+martensites, have been evaluated by ab initio calculations based on the density
+functional theory. The energy of a strained crystal has been computed using the
+supercell method at several values of the strain intensity, and the stiffness
+coefficient has been determined from the slope of the energy versus square of
+strain relation. Some of the third order elastic constants have also been
+evaluated. The absolute magnitudes of the calculated values for bcc iron are in
+fair agreement with experiment, including the third order constants, although
+the computed elastic anisotropy is much weaker than measured. The tetragonally
+distorted dilute FeC and FeN alloys exhibit lower stiffness than bcc iron,
+particularly in the tensor component C33, while the elastic anisotropy is
+virtually the same. Average values of elastic moduli for polycrystalline
+aggregates are also computed. Youngs modulus and the rigidity modulus, as well
+as the bulk modulus, are decreased by about 10 per cent by the addition of C or
+N to 3.7 atomic per cent, which agrees with the experimental data for FeC
+martensite.",1508.00521v1
+2015-08-04,A Critical Analysis of the Feasibility of Pure Strain-Actuated Giant Magnetostrictive Nanoscale Memories,"Concepts for memories based on the manipulation of giant magnetostrictive
+nanomagnets by stress pulses have garnered recent attention due to their
+potential for ultra-low energy operation in the high storage density limit.
+Here we discuss the feasibility of making such memories in light of the fact
+that the Gilbert damping of such materials is typically quite high. We report
+the results of numerical simulations for several classes of toggle precessional
+and non-toggle dissipative magnetoelastic switching modes. Material candidates
+for each of the several classes are analyzed and forms for the anisotropy
+energy density and ranges of material parameters appropriate for each material
+class are employed. Our study indicates that the Gilbert damping as well as the
+anisotropy and demagnetization energies are all crucial for determining the
+feasibility of magnetoelastic toggle-mode precessional switching schemes. The
+roles of thermal stability and thermal fluctuations for stress-pulse switching
+of giant magnetostrictive nanomagnets are also discussed in detail and are
+shown to be important in the viability, design, and footprint of
+magnetostrictive switching schemes.",1508.00629v2
+2015-08-04,Scanning Kerr microscopy of current induced switching in Ta/CoFeB/MgO films with perpendicular magnetic anisotropy,"Ta/CoFeB/MgO trilayers with perpendicular magnetic anisotropy are expected to
+play a key role in the next generation of current and electric field switched
+memory and logic devices. In this study we use Kerr microscopy alongside
+electrical transport measurement to gain insight into the underlying switching
+mechanisms of such devices. We find switching to be a stochastic, domain wall
+driven process, the speed of which is strongly dependent on the switching
+current. Kerr imaging shows domain nucleation at the edge of the device which
+modelling reveals is likely assisted by the perpendicular component of the
+Oersted field. Further domain growth, leading to magnetisation reversal may be
+assisted by spin torques.",1508.00833v2
+2015-08-11,Stochastic Eternal Inflation in a Bianchi Type I Universe,"The phenomenon of stochastic eternal inflation is studied for a chaotic
+inflation potential in a Bianchi Type I spacetime background. After deriving
+the appropriate stochastic Klein-Gordon equation, we give details on the
+conditions for eternal inflation. It is shown that for eternal inflation to
+occur, the amount of anisotropy must be small. In fact, it is shown that
+eternal inflation will only take place if the shear anisotropy variables take
+on values within a small region of the interior of the Kasner circle. We then
+calculate the probability of eternal inflation occurring based on techniques
+from stochastic calculus.",1508.02670v6
+2015-08-13,Anisotropic distributions in a multi-phase transport model,"With A Multi-Phase Transport (AMPT) model we investigate the relation between
+the magnitude, fluctuations and correlations of the initial state spatial
+anisotropy $\varepsilon_{n}$ and the final state anisotropic flow coefficients
+$v_{n}$ in Au+Au collisions at $\sqrt{s_{_{\rm NN}}}=$ 200 GeV. It is found
+that the relative eccentricity fluctuations in AMPT account for the observed
+elliptic flow fluctuations, in agreement with measurements of the STAR
+collaboration. In addition, the studies based on 2- and multi-particle
+correlations and event-by-event distributions of the anisotropies suggest that
+the Elliptic-Power function is a promising candidate of the underlying
+probability density function of the event-by-event distributions of
+$\varepsilon_{n}$ as well as $v_{n}$. Furthermore, the correlations between
+different order symmetry planes and harmonics in the initial coordinate space
+and final state momentum space are presented. Non-zero values of these
+correlations have been observed. The comparison between our calculations and
+data will, in the future, shed new insight into the nature of the fluctuations
+of the Quark-Gluon Plasma produced in heavy ion collisions.",1508.03306v2
+2015-08-17,Engineering the magnetic anisotropy of atomic-scale nanostructure under electric field,"Atomic-scale magnetic nanostructures are promising candidates for future
+information processing devices. Utilizing external electric field to manipulate
+their magnetic properties is an especially thrilling project. Here, by careful
+identifying different contributions of each atomic orbital to the magnetic
+anisotropy energy (MAE) of the ferromagnetic metal films, we argue that it is
+possible to engineer both the MAE and the magnetic response to the electric
+field of atomic-scale magnetic nanostructures. Taking the iron monolayer as a
+matrix, we propose several interesting iron nanostructures with dramatically
+different magnetic properties. Such nanostructures could exhibit strong
+magnetoelectric effect. Our work may open a new avenue to the artificial design
+of electrically controlled magnetic devices.",1508.03917v1
+2015-08-23,A study of the physical properties of single crystalline Fe5B2P,"Single crystals of Fe5B2P were grown by self-flux growth technique.
+Structural and magnetic properties are studied. The Curie temperature of Fe5B2P
+is determined to be 655$pm$2K. The saturation magnetization is determined to be
+1.72 MuB/Fe at 2K. The temperature variation of the anisotropy constant K1 is
+determined for the first time, reaching ~0.50 MJ/m3 at 2K, and it is comparable
+to that of hard ferrites. The saturation magnetization is found to be larger
+than the hard ferrites. The first principle calculations of saturation
+magnetization and anisotropy constant are found to be consistent with the
+experimental results.",1508.05629v1
+2015-08-31,All electrical manipulation of magnetization dynamics in a ferromagnet by antiferromagnets with anisotropic spin Hall effects,"We investigate spin-orbit torques of metallic CuAu-I-type antiferromagnets
+using spin-torque ferromagnetic resonance tuned by a dc-bias current. The
+observed spin torques predominantly arise from diffusive transport of spin
+current generated by the spin Hall effect. We find a growth-orientation
+dependence of the spin torques by studying epitaxial samples, which may be
+correlated to the anisotropy of the spin Hall effect. The observed anisotropy
+is consistent with first-principles calculations on the intrinsic spin Hall
+effect. Our work demonstrates large tunable spin-orbit effects in
+magnetically-ordered materials.",1508.07906v2
+2015-09-01,Elusive pure anapole excitation in homogenous spherical nanoparticles with radial anisotropy,"For homogenous isotropic dielectric nanospheres with incident plane waves,
+Cartesian electric and toroidal dipoles can be tunned to cancel each other in
+terms of far-field scattering, leading to the effective anopole excitation. At
+the same time however, other multipoles such as magnetic dipoles with
+comparable scattered power are simultanesouly excited, mixing with the anopole
+and leading to a non-negligible total scattering cross section. Here we show
+that for homogenous dielectric nanospheres, radial anisotropy can be employed
+to significantly suppress the other multipole excitation, which at the same
+time does not compromise the property of complete scattering cancallation
+between Cartesian electric and toroidal dipoles. This enables an elusive pure
+anopole excitation within radially anisotropic dielectric nanospheres, which
+may shed new light to many scattering related fundamental researches and
+applications.",1509.00119v1
+2015-09-04,Computational up-scaling of anisotropic swelling and mechanical behavior of hierarchical cellular material,"The hygro-mechanical behavior of a hierarchical cellular material, i.e.
+growth rings of softwood is investigated using a two-scale micro-mechanics
+model based on a computational homogenization technique. The lower scale
+considers the individual wood cells of varying geometry and dimensions.
+Honeycomb unit cells with periodic boundary conditions are utilized to
+calculate the mechanical properties and swelling coefficients of wood cells.
+Using the cellular scale results, the anisotropy in mechanical and swelling
+behavior of a growth ring in transverse directions is investigated. Predicted
+results are found to be comparable to experimental data. It is found that the
+orthotropic swelling properties of the cell wall in thin-walled earlywood cells
+produce anisotropic swelling behavior while, in thick latewood cells, this
+anisotropy vanishes. The proposed approach provides the ability to consider the
+complex microstructure when predicting the effective mechanical and swelling
+properties of softwood.",1509.01388v1
+2015-09-07,Successively Thresholded Domain Boundary Roughening Driven by Pinning Centers and Missing Bonds: Hard-Spin Mean-Field Theory Applied to d=3 Ising Magnets,"Hard-spin mean-field theory has recently been applied to Ising magnets,
+correctly yielding the absence and presence of an interface roughening
+transition respectively in $d=2$ and $d=3$ dimensions and producing the
+ordering-roughening phase diagram for isotropic and anisotropic systems. The
+approach has now been extended to the effects of quenched random pinning
+centers and missing bonds on the interface of isotropic and anisotropic Ising
+models in $d=3$. We find that these frozen impurities cause domain boundary
+roughening that exhibits consecutive thresholding transitions as a function
+interaction of anisotropy. For both missing-bond and pinning-center impurities,
+for moderately large values the anisotropy, the systems saturate to the
+""solid-on-solid"" limit, exhibiting a single universal curve for the domain
+boundary width as a function of impurity concentration.",1509.01910v2
+2015-09-07,Giant exchange interaction in mixed lanthanides,"Combining strong magnetic anisotropy with strong exchange interaction is a
+long standing goal in the design of quantum magnets. The lanthanide complexes,
+while exhibiting a very strong ionic anisotropy, usually display a weak
+exchange coupling, amounting to only a few wavenumbers. Recently, an
+isostructural series of mixed Ln$^{3+}$-N$_2^{3-}$-Ln$^{3+}$ (Ln $=$ Gd, Tb,
+Dy, Ho, Er) have been reported, in which the exchange splitting is estimated to
+reach hundreds wavenumbers. The microscopic mechanism governing the unusual
+exchange interaction in these compounds is revealed here by combining detailed
+modeling with density-functional theory and {\it ab initio} calculations. We
+find it to be basically kinetic and highly complex, involving non-negligible
+contributions up to seventh power of total angular momentum of each lanthanide
+site. The performed analysis also elucidates the origin of magnetization
+blocking in these compounds. Contrary to general expectations the latter is not
+always favored by strong exchange interaction.",1509.02206v4
+2015-09-08,Magnetic and structural properties of ferromagnetic Fe5PB2 and Fe5SiB2 and effects of Co and Mn substitutions,"Crystallographic and magnetic properties of Fe5PB2, Fe4CoPB2, Fe4MnPB2,
+Fe5SiB2, Fe4CoSiB2, and Fe4MnSiB2 are reported. All adopt the tetragonal Cr5B3
+structure-type and are ferromagnetic at room temperature with easy axis of
+magnetization along the c-axis. The spin reorientation in Fe5SiB2 is observed
+as an anomaly in the magnetization near 170 K, and is suppressed by
+substitution of Co or Mn for Fe. The silicides are found to generally have
+larger magnetic moments than the phosphides, but the data suggests smaller
+magnetic anisotropy in the silicides. Cobalt substitution reduces the Curie
+temperatures by more than 100 K and ordered magnetic moments by 16-20%, while
+manganese substitution has a much smaller effect. This suggests Mn moments
+align ferromagnetically with the Fe and that Co does not have an ordered moment
+in these structures. Anisotropic thermal expansion is observed in Fe5PB2 and
+Fe5SiB2, with negative thermal expansion seen along the c-axis of Fe5SiB2.
+First principles calculations of the magnetic properties of Fe5SiB2 and
+Fe4MnSiB2 are reported. The results, including the magnetic moment and
+anisotropy, and are in good agreement with experiment.",1509.02544v1
+2015-09-10,Impact of anisotropy on the interaction of an atom with a one-dimensional nano-grating,"We study the interaction of an atom with a one-dimensional nano-grating
+within the framework of macroscopic QED, with special emphasis on possible
+anisotropic contributions. To this end, we first derive the scattering Green's
+tensor of the grating by means of a Rayleigh expansion and discuss its symmetry
+properties and asymptotes. We then determine the Casimir--Polder potential of
+an atom with the grating. In particular, we find that strong anisotropy can
+lead to a repulsive Casimir--Polder potential in the normal direction.",1509.03117v1
+2015-09-15,Magnetization reversal of giant perpendicular magnetic anisotropy at the magnetic-phase transition in FeRh films on MgO,"Phenomena originated from spin-orbit interaction, such as magnetic anisotropy
+(MA), Rashba-type interactions, or topological insulators, have drawn huge
+attention for its intriguing physics. In particular, the search for a novel
+antiferromagnetic material, with potentially large perpendicular MA (PMA), has
+been becoming very intensive for next-generation high density memory
+applications. Here, we propose that substitutions of transition metals Ru and
+Ir, neighboring and same group elements in the periodic table, for the Rh site
+in the vicinity of surface can induce a substantially large PMA, up to an order
+of magnitude of 20 erg/cm2, in FeRh films on MgO. The main driving mechanism
+for this huge PMA is the interplay between the dxy and dx2-y2 states of strong
+spin-orbit 4d and 5d orbitals. Further investigations demonstrate that
+magnetization direction of PMA undergoes a transition into an in-plane
+magnetization at the antiferromagnetic-to-ferromagnetic phase transition, which
+provides a viable route for achieving large and switchable PMA associated with
+the magnetic-phase transition in antiferromagnetic spintronics.",1509.04361v2
+2015-09-16,A spin dynamics approach to solitonics,"It is spatial dispersion which is exclusively responsible for the emergence
+of exchange interaction and magnetic ordering. In contrast, magneto-crystalline
+anisotropy present in any realistic material brings in a certain non-linearity
+to the equation of motion. Unlike homogeneous ferromagnetic ordering a variety
+of non-collinear ground state configurations emerge as a result of competition
+among exchange, anisotropy, and dipole-dipole interaction. These particle-like
+states, e.g. magnetic soliton, skyrmion, domain wall, form a spatially
+localised clot of magnetic energy. In this paper we explore topologically
+protected magnetic solitons that might potentially be applied for logical
+operations and/or information storage in the rapidly advancing filed of
+solitonics (and skyrmionics). An ability to easily create, address, and
+manipulate such structures is among the prerequisite forming a basis of -onics
+technology, and is investigated in detail here using numerical and analytical
+tools.",1509.04860v2
+2015-09-17,Antiferromagnetic Spin Wave Field-Effect Transistor,"In a collinear antiferromagnet with easy-axis anisotropy, symmetry dictates
+that the spin wave modes must be doubly degenerate. Theses two modes,
+distinguished by their opposite polarization and available only in
+antiferromagnets, give rise to a novel degree of freedom to encode and process
+information. We show that the spin wave polarization can be manipulated by an
+electric field induced Dzyaloshinskii-Moriya interaction and magnetic
+anisotropy. We propose a prototype spin wave field-effect transistor which
+realizes a gate-tunable magnonic analog of the Faraday effect, and demonstrate
+its application in THz signal modulation. Our findings open up the exciting
+possibility of digital data processing utilizing antiferromagnetic spin waves
+and enable the direct projection of optical computing concepts onto the
+mesoscopic scale.",1509.05295v3
+2015-09-20,Emergent formation of dynamic topographic patterns in electron beam induced etching,"Spontaneous formation of geometric patterns is a fascinating, ubiquitous
+process that provides fundamental insights into the roles of symmetry breaking,
+anisotropy and nonlinear interactions in emergent phenomena. Here we report
+dynamic, highly ordered topographic patterns on the surface of diamond that
+span multiple length scales and have a symmetry controlled by the chemical
+species of a precursor gas used in electron beam induced etching (EBIE). This
+behavior reveals an underlying etch rate anisotropy and an electron energy
+transfer pathway that has been overlooked by existing EBIE theory. We present
+an etch rate kinetics model that fully explains our results and is universally
+applicable to EBIE. Our findings can be exploited for controlled wetting,
+optical structuring and other emerging applications that require nano and
+micro-scale surface texturing.",1509.05963v1
+2015-09-22,The production of photons in relativistic heavy-ion collisions,"In this work it is shown that the use of a hydrodynamical model of heavy ion
+collisions which incorporates recent developments, together with updated photon
+emission rates greatly improves agreement with both ALICE and PHENIX
+measurements of direct photons, supporting the idea that thermal photons are
+the dominant source of direct photon momentum anisotropy. The event-by-event
+hydrodynamical model uses IP-Glasma initial states and includes, for the first
+time, both shear and bulk viscosities, along with second order couplings
+between the two viscosities. The effect of both shear and bulk viscosities on
+the photon rates is studied, and those transport coefficients are shown to have
+measurable consequences on the photon momentum anisotropy.",1509.06738v3
+2015-09-27,Perpendicular magnetic anisotropy and spin glass-like behavior in molecular beam epitaxy grown chromium telluride thin films,"Reflection high energy electron diffraction (RHEED), scanning tunneling
+microscopy (STM), vibrating sample magnetometry and other physical property
+measurements are used to investigate the structure, morphology, magnetic and
+magneto-transport properties of (001)-oriented Cr$_2$Te$_3$ thin films grown on
+Al$_2$O$_3$(0001) and Si(111)-(7$\times$7) surfaces by molecular beam epitaxy
+(MBE). Streaky RHEED patterns indicate flat smooth film growth on both
+substrates. STM studies show the hexagonal arrangements of surface atoms.
+Determination of the lattice parameter from atomically resolved STM image is
+consistent with the bulk crystal structures. Magnetic measurements show the
+film is ferromagnetic having the Curie temperature of about 180 K, and a spin
+glass-like behavior was observed below 35 K. Magneto-transport measurements
+show the metallic nature of the film with a perpendicular magnetic anisotropy
+along the $c$-axis.",1509.08140v1
+2015-09-29,Field-free magnetization reversal by spin-Hall effect and exchange bias,"Magnetic random-access memory (MRAM) driven by spin-transfer torque (STT) is
+a major contender for future memory applications. The energy dissipation
+involved in writing remains problematic, even with the advent of more efficient
+perpendicular magnetic anisotropy (PMA) devices. A promising alternative
+switching mechanism employs spin-orbit torques and the spin-Hall effect (SHE)
+in particular, but additional symmetry breaking is required to achieve
+deterministic switching in PMA devices. Currently used methods rely on in-plane
+magnetic fields or anisotropy gradients, which are not suitable for practical
+applications. Here, we interface the magnetic layer with an anti-ferromagnetic
+material. An in-plane exchange bias (EB) is created, and shown to enable
+field-free SHE-driven magnetization reversal of a perpendicularly magnetized
+Pt/Co/IrMn structure. Aside from the potential technological implications, our
+experiment provides additional insight into the local spin structure at the
+ferromagnetic/anti-ferromagnetic interface.",1509.08752v2
+2015-09-30,Essential properties of the Difference Method for the Search of the Anisotropy of the Primary Cosmic Radiation,"The methodical properties of the original difference method for the search of
+the anisotropy at the knee region of the primary cosmic radiation energy
+spectrum are analyzed. The main feature of the suggested method is a study of
+the difference in the EAS characteristics in different directions but not their
+intensity. It is shown that the method is stable to the random experimental
+errors and allows to separate the anomalies related to the laboratory
+coordinate system from the anomalies in the celestial coordinates. The method
+uses multiple scattering of the charge particles in the Galaxy magnetic fields
+to study the whole celestial sphere including the regions outside of the line
+of sight of the installation.",1509.09316v1
+2015-10-01,Collectivity in Small QCD Systems,"Features of collectivity observed in high energy A+A collision systems at the
+Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC)
+imply a strongly coupled quark gluon plasma (QGP) that flows. One defining
+feature of collectivity is long-range angular correlations which are
+characterized experimentally by measuring the azimuthal anisotropy of particles
+well separated in rapidity. Evidence indicating long-range angular correlations
+include the appearance of the so-called near-side ""ridge"" in correlation
+functions and $p_T$ dependent flow components ($v_N$). These features have been
+well measured at RHIC for Au+Au collisions at $\sqrt{s_{NN}} $= 200 GeV and at
+the LHC for Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. However, evidence
+of collectivity has recently been observed at the LHC in p+p high multiplicity
+collisions at $\sqrt{s_{NN}}$ = 7.0 TeV and p+Pb collisions at $\sqrt{s_{NN}}$
+= 5.02 TeV and then at RHIC in d+Au and $3^He$+Au collisions at $\sqrt{s_{NN}}$
+= 200 GeV. In this talk, we present the recent PHENIX results for d+Au and
+$^3He$+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Precise measurements of
+anisotropy help distinguish between theoretical models based on relativistic
+hydrodynamics or Color Glass Condensate (CGC). Comparisons of these
+measurements to various theoretical models are shown.",1510.00435v1
+2015-10-03,"Giant magnetic anisotropy of Co, Ru, and Os adatoms on MgO (001) surface","Large magnetic anisotropy energy (MAE) is desirable and critical for
+nanoscale magnetic devices. Here, using ligand-field level diagrams and density
+functional calculations, we well explain the very recent discovery [I. G. Rau
+et al., Science 344, 988 (2014)] that an individual Co adatom on a MgO (001)
+surface has a large MAE of more than 60 meV. More importantly, we predict that
+a giant MAE up to 110 meV could be realized for Ru adatoms on MgO (001), and
+even more for the Os adatoms (208 meV). This is a joint effect of the special
+ligand field, orbital multiplet, and significant spin-orbit interaction, in the
+intermediate-spin state of the Ru or Os adatoms on top of the surface oxygens.
+The giant MAE could provide a route to atomic scale memory.",1510.00788v1
+2015-10-07,"Tunable damping, saturation magnetization, and exchange stiffness of half-Heusler NiMnSb thin films","The half-metallic half-Heusler alloy NiMnSb is a promising candidate for
+applications in spintronic devices due to its low magnetic damping and its rich
+anisotropies. Here we use ferromagnetic resonance (FMR) measurements and
+calculations from first principles to investigate how the composition of the
+epitaxially grown NiMnSb influences the magnetodynamic properties of saturation
+magnetization $M_S$, Gilbert damping $\alpha$, and exchange stiffness $A$.
+$M_S$ and $A$ are shown to have a maximum for stoichiometric composition, while
+the Gilbert damping is minimum. We find excellent quantitative agreement
+between theory and experiment for $M_S$ and $\alpha$. The calculated $A$ shows
+the same trend as the experimental data, but has a larger magnitude.
+Additionally to the unique in-plane anisotropy of the material, these
+tunabilities of the magnetodynamic properties can be taken advantage of when
+employing NiMnSb films in magnonic devices.",1510.01894v1
+2015-10-08,Recovering hidden signals of statistical anisotropy from a masked or partial CMB sky,"Any isotropy violating phenomena on cosmic microwave background (CMB) induces
+off-diagonal correlations in the two-point function. These correlations
+themselves can be used to estimate the underlying anisotropic signals. Masking
+due to residual foregrounds, or availability of partial sky due to survey
+limitation, are unavoidable circumstances in CMB studies. But, masking induces
+additional correlations, and thus complicates the recovery of such signals. In
+this work, we discuss a procedure based on bipolar spherical harmonic (BipoSH)
+formalism to comprehensively addresses any spurious correlations induced by
+masking and successfully recover hidden signals of anisotropy in observed CMB
+maps. This method is generic, and can be applied to recover a variety of
+isotropy violating phenomena. Here, we illustrate the procedure by recovering
+the subtle Doppler boost signal from simulated boosted CMB skies, which has
+become possible with the unprecedented full-sky sensitivity of PLANCK probe.",1510.02454v1
+2015-10-15,Lipkin-Meshkov-Glick Model in a Quantum Otto Cycle,"Lipkin-Meshkov-Glick model of two anisotropically interacting spins in a
+magnetic field is proposed as a working substance of a quantum Otto engine to
+explore and exploit the anisotropy effects for the optimization of engine
+operation. Three different cases for the adiabatic branches of the cycle have
+been considered. In the first two cases, either the magnetic field or coupling
+strength are changed; while in the third case, both the magnetic field and the
+coupling strength are changed by the same ratio. The system parameters for
+which the engine can operate similar to or dramatically different from the
+engines of non-interacting spins or of coupled spins with Ising model or
+isotropic XY model interactions are determined. In particular, the role of
+anisotropy to enhance cooperative work, and to optimize maximum work with high
+efficiency, as well as to operate the engine near the Carnot bound are
+revealed.",1510.04495v3
+2015-10-16,Enhanced orbital magnetic moments in magnetic heterostructures with interface perpendicular magnetic anisotropy,"We have studied the magnetic layer thickness dependence of the orbital
+magnetic moment in magnetic heterostructures to identify contributions from
+interfaces. Three different heterostructures, Ta/CoFeB/MgO, Pt/Co/AlO$_x$ and
+Pt/Co/Pt, which possess significant interface contribution to the perpendicular
+magnetic anisotropy, are studied as model systems. X-ray magnetic circular
+dichroism spectroscopy is used to evaluate the relative orbital moment, i.e.
+the ratio of the orbital to spin moments, of the magnetic elements constituting
+the heterostructures. We find that the relative orbital moment of Co in
+Pt/Co/Pt remains constant against its thickness whereas the moment increases
+with decreasing Co layer thickness for Pt/Co/AlO$_x$, suggesting that a
+non-zero interface orbital moment exists for the latter system. For
+Ta/CoFeB/MgO, a non-zero interface orbital moment is found only for Fe. X-ray
+absorption spectra shows that a particular oxidized Co state in Pt/Co/AlO$_x$,
+absent in other heterosturctures, may give rise to the interface orbital moment
+in this system. These results show element specific contributions to the
+interface orbital magnetic moments in ultrathin magnetic heterostructures.",1510.04756v1
+2015-10-16,Ground-state phase diagram of an anisotropic S=1/2 ladder with alternating rung interactions,"Employing mainly numerical methods, we explore the ground-state phase diagram
+of an anisotropic $S=1/2$ ladder, in which leg interactions are uniform and
+isotropic, while rung interactions are alternating and have a common Ising-type
+anisotropy. We determine the phase diagram in the case where $J_{\rm leg}=0.2$
+(antiferromagnetic), $J_{\rm rung}=-1.0$ (ferromagnetic) and $|J_{\rm
+rung}'|\!\leq\!1.0$, the first one being the magnitude of the leg interaction
+and the second and third ones those of the rung interactions, which are
+alternating. It is emphasized that the system has a frustration when $J_{\rm
+rung}'$ is positive. We find that, in the frustrated region, the Haldane state
+appears as the ground state even when the Ising character of rung interactions
+is strong. This appearance of the Haldane phase is contrary to the ordinary
+situation, and it is called the inversion phenomenon concerning the interaction
+anisotropy. We also find that an incommensurate state becomes the ground state
+in a portion of the Haldane phase region.",1510.04928v1
+2015-10-19,Effect of magnetism on lattice dynamics in SrFe$_2$As$_2$ as seen via high resolution inelastic x-ray scattering,"Phonon spectra of detwinned {SrFe$_2$As$_2$} crystals, as measured by
+inelastic x-ray scattering, show clear anisotropy accompanying the
+magneto-structural transition at 200 K. We model the mode splitting using
+magnetic DFT calculations, including a phenomenological reduction in
+force-constant anisotropy that can be attributed to magnetic fluctuations. This
+serves as a starting point for a general model of phonons in this material
+applicable to both magnetic and non-magnetic phase. Using this model, the
+measured splitting in the magnetic phase below $\it T_{N}$, and the measured
+phonon linewidth, we set a lower bound on the mean magnetic fluctuation
+frequency above $\it T_{N}$ at 210 K.",1510.05487v2
+2015-10-23,Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet,"Laser-induced magnetization precessional dynamics was investigated in
+epitaxial films of Mn$_3$Ge, which is a tetragonal Heusler-like nearly
+compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed,
+the precession frequency for which exceeded 0.5 THz and originated from the
+large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet.
+The effective damping constant was approximately 0.03. The corresponding
+effective Landau-Lifshitz constant of approximately 60 Mrad/s and is comparable
+to those of the similar Mn-Ga materials. The physical mechanisms for the
+Gilbert damping and for the laser-induced excitation of the FMR mode were also
+discussed in terms of the spin-orbit-induced damping and the laser-induced
+ultrafast modulation of the magnetic anisotropy, respectively.",1510.06793v1
+2015-10-26,Analytic theory for the switch from Bloch to Néel domain wall in nanowires with perpendicular anisotropy,"Rectangular nanowires may have domain walls nucleated and moved through them
+to realize many devices. It has been shown that at a particular width and
+thickness of a nanowire with perpendicular anisotropy, there is a switch from
+the domain wall being of Bloch-type to it being of N\'eel-type. This critical
+shape can be found through micromagnetics simulations, but here we present an
+analytic calculation for the energies of both wall types involving two
+iterations for the demagnetizing energy density. The expressions developed are
+long, but have the advantage that by simply inputting material parameters for
+the magnetic material, the critical shape can be found using a calculator in a
+matter of seconds. We compare our results to those found using micromagnetics
+and those found experimentally and the agreement is good.",1510.07673v1
+2015-10-27,Extrinsic Spin Hall Effect from Anisotropic Rashba Spin-Orbit Coupling in Graphene,"We study the effect of anisotropy of the Rashba coupling on the extrinsic
+spin Hall effect due to spin-orbit active adatoms on graphene. In addition to
+the intrinsic spin-orbit coupling, a generalized anisotropic Rashba coupling
+arising from the breakdown of both mirror and hexagonal symmetries of pristine
+graphene is considered. We find that Rashba anisotropy can strongly modify the
+dependence of the spin Hall angle on carrier concentration. Our model provides
+a simple and general description of the skew scattering mechanism due to the
+spin-orbit coupling that is induced by proximity to large adatom clusters.",1510.07771v1
+2015-11-01,"Growth and characterization of R(O,F)BiS2 (R = La, Ce, Pr, Nd) superconducting single crystals","R(O,F)BiS2 (R: La, Ce, Pr, Nd) superconducting single crystals with different
+F concentrations are grown using a CsCl/KCl flux. The obtained 1-2 mm-sized
+single crystals have a plate-like shape and are cleavable along the ab-plane.
+The crystal structure is tetragonal of space group P4/nmm (#129). The as-grown
+single crystals exhibit superconductivity at around 3-5 K. The superconducting
+transition temperature increases with decreasing the ionic radius of the R
+element. The superconducting anisotropies of the R(O,F)BiS2 single crystals are
+estimated to be 30-60 according to the effective mass model, whereas the
+anisotropies for Ce(O,F)BiS2 single crystals are 13-21. The c-axis transport
+measurements of a single crystal of Pr(O,F)BiS2 under a magnetic field parallel
+to the ab-plane reveal a ""lock-in"" state attributed to the Josephson vortex
+flow. Furthermore, the Ce(O,F)BiS2 single crystals exhibit a magnetic order at
+the temperature range of 5-7 K that apparently coexist with superconductivity
+below approximately 3 K.",1511.00219v1
+2015-11-03,A hybrid method for anisotropic elliptic problems based on the coupling of an Asymptotic-Preserving method with the Asymptotic-Limit model,"This paper presents a hybrid numerical method to solve efficiently a class of
+highly anisotropic elliptic problems. The anisotropy is aligned with one
+coordinate-axis and its strength is described by a parameter $\eps \in (0,1]$,
+which can largely vary in the study domain. Our hybrid model is based on
+asymptotic techniques and couples (spatially) an Asymptotic-Preserving model
+with its asymptotic Limit model, the latter being used in regions where the
+anisotropy parameter $\eps$ is small. Adequate coupling conditions link the two
+models. Aim of this hybrid procedure is to reduce the computational time for
+problems where the region of small $\eps$-values extends over a significant
+part of the domain, and this due to the reduced complexity of the limit model.",1511.00917v1
+2015-11-05,Early-Matter-Like Dark Energy and the Cosmic Microwave Background,"Early-matter-like dark energy is defined as a dark energy component whose
+equation of state approaches that of cold dark matter (CDM) at early times.
+Such a component is an ingredient of unified dark matter (UDM) models, which
+unify the cold dark matter and the cosmological constant of the LambdaCDM
+concordance model into a single dark fluid. Power series expansions in
+conformal time of the perturbations of the various components for a model with
+early-matter-like dark energy are provided. They allow the calculation of the
+cosmic microwave background (CMB) anisotropy from the primordial initial values
+of the perturbations. For a phenomenological UDM model, which agrees with the
+observations of the local Universe, the CMB anisotropy is computed and compared
+with the CMB data. It is found that a match to the CMB observations is possible
+if the so-called effective velocity of sound c_eff of the early-matter-like
+dark energy component is very close to zero. The modifications on the CMB
+temperature and polarization power spectra caused by varying the effective
+velocity of sound are studied.",1511.01691v2
+2015-11-09,Theoretical and experimental investigation of optical absorption anisotropy in $β$-Ga2O3,"The question of optical bandgap anisotropy in the monoclinic semiconductor
+$\beta$-Ga2O3 was revisited by combining accurate optical absorption
+measurements with theoretical analysis, performed using different advanced
+computation methods. As expected, the bandgap edge of bulk $\beta$-Ga2O3 was
+found to be a function of light polarization and crystal orientation, with the
+lowest onset occurring at polarization in the ac crystal plane around 4.5-4.6
+eV; polarization along b unambiguously shifts the onset up by 0.2 eV. The
+theoretical analysis clearly indicates that the shift of the b onset is due to
+a suppression of the transition matrix elements of the three top valence bands
+at $\Gamma$ point.",1511.02601v1
+2015-11-11,Dynamics of wave fronts and filaments in anisotropic cardiac tissue,"The heartbeat is mediated between cardiac cells by waves of electrical
+depolarisation. During cardiac arrhythmias, electrical activity was found to be
+organised in scroll waves which rotate around a dynamical filament curve. In
+this thesis, a curved-space approach is used to mathematically capture
+anisotropy of wave propagation. We derive for the first time the covariant laws
+of motion for traveling wave fronts and scroll wave filaments in anisotropic
+excitable media such as cardiac tissue. We show that locally varying anisotropy
+yields non-zero Riemann tensor components, which may alter the stability of
+scroll wave filaments. The instability of scroll wave filaments has been linked
+to transition from ventricular tachycardia to fibrillation.",1511.03685v1
+2015-11-17,Low-field behavior of an XY pyrochlore antiferromagnet: emergent clock anisotropies,"Using $\rm Er_2Ti_2O_7$ as a motivation, we investigate finite-field
+properties of $XY$ pyrochlore antiferromagnets. In addition to a
+fluctuation-induced six-fold anisotropy present in zero field, an external
+magnetic field induces a combination of two-, three-, and six-fold clock terms
+as a function of its orientation providing for a rich and controllable
+magnetothermodynamics. For $\rm Er_2Ti_2O_7$, we predict a new phase transition
+for ${\bf H}\parallel [001]$. Re-entrant transitions are also found for ${\bf
+H}\parallel [111]$. We extend these results to the whole family the $XY$
+pyrochlore antiferromagnets and show that presence and number of low-field
+transitions for different orientations can be used for locating a given
+material in the parameter space of anisotropic pyrochlores. Finite-temperature
+classical Monte Carlo simulations serve to confirm and illustrate these
+analytic predictions.",1511.05319v2
+2015-11-24,Electronic and Magnetic Properties of single Fe atoms on a CuN Surface; Effects of Electron Correlations,"The electronic structure and magnetic properties of a single Fe adatom on a
+CuN surface have been studied using density functional theory in the local spin
+density approximation (LSDA), the LSDA+U approach and the local density
+approximation plus dynamical mean-field theory (LDA+DMFT). The impurity problem
+in LDA+DMFT is solved through exact diagonalization and in the Hubbard-I
+approximation. The comparison of the one-particle spectral functions obtained
+from LSDA, LSDA+U and LDA+DMFT show the importance of dynamical correlations
+for the electronic structure of this system. Most importantly, we focused on
+the magnetic anisotropy and found that neither LSDA, nor LSDA+U can explain the
+measured, high values of the axial and transverse anisotropy parameters.
+Instead, the spin excitation energies obtained from our LDA+DMFT approach with
+exact diagonalization agree significantly better with experimental data. This
+affirms the importance of treating fluctuating magnetic moments through a
+realistic many-body treatment when describing this class of nano-magnetic
+systems. Moreover, it facilitates insight to the role of the hybridization with
+surrounding orbitals.",1511.07909v1
+2015-11-27,Resonance spin-charge phenomena and mechanism of magnetoresistance anisotropy in manganite/metal bilayer structures,"The dc voltage generated under ferromagnetic resonance has been studied in
+bilayer structures based on manganite thin epitaxial films La0.67Sr0.33MnO3
+(LSMO) and non-magnetic metals (Au, Pt, and SrRuO3) in the temperature range up
+to the Curie point. The effect is shown to be caused by two different
+phenomena: (1) the resonance dc electromotive force related to anisotropic
+magnetoresistance (AMR) in the manganite film and (2) pure spin current (spin
+pumping) registered by means of the inverse spin Hall effect in normal metal.
+The two phenomena were separated using the angular dependence of the effect,
+the external magnetic field H0 being rotated in the film plane. It was found
+that the AMR mechanism in the manganite films differs substantially from that
+in traditional ferromagnetic metals being governed by the colossal
+magnetoresistance together with the in-plane magnetic anisotropy. The spin
+pumping effect registered in the bilayers was found to be much lower than that
+reported for common ferromagnets; possible reasons are discussed.",1511.08664v1
+2015-11-27,Multi-band superconductivity and large anisotropy in FeS crystals,"By using a hydrothermal method, we have successfully grown crystals of the
+newly discovered superconductor FeS, which has an isostructure of the iron
+based superconductor FeSe. The superconductivity appears at about 4.5K, as
+revealed by both resistive and magnetization measurements. It is found that the
+upper critical field is relatively low, with however an rather large anisotropy
+$\Gamma=[(dH_{c2}^{ab}/dT)/(dH_{c2}^{c}/dT)]_{T_c}\approx5.8$. A huge
+magnetoresistivity (290$\%$ at 9T and 10K, ${H}$ $\parallel$ c-axis) together
+with a non-linear behavior of Hall resistivity vs. external field are observed.
+A two-band model is applied to fit the magnetoresistance and non-linear
+transverse resistivity, yielding the basic parameters of the electron and hole
+bands.",1511.08716v2
+2015-12-05,A new exact solution for anisotropic compact stars of embedding class one,"We have presented a new anisotropic solution of Einstein's field equations
+for compact star models. The Einstein's field equations are solved by using the
+class one condition \cite{1}. After that we constructed the physically valid
+expression of anisotropy factor by the help of metric potentials and there
+after we obtained the physical parameters like energy density, radial and
+transverse pressure. These models parameters are well behaved inside the
+compact star and satisfy all the required physical conditions. Also we observed
+a very interesting result that all the physical parameters are depend on the
+anisotropy factor. The present compact star models are quite compatible with
+the observational astrophysical compact stellar objects like Her X-1, RXJ
+1856-37, SAX J1808.4-3658(SS1), SAX J1808.4-3658(SS2)",1512.01667v2
+2015-12-18,Exchange Bias and Bistable Magneto-Resistance States in Amorphous TbFeCo thin Films,"Amorphous TbFeCo thin films sputter deposited at room temperature on
+thermally oxidized Si substrate are found to exhibit strong perpendicular
+magnetic anisotropy (PMA). Atom probe tomography (APT), scanning transmission
+electron microscopy (STEM), and energy dispersive spectroscopy (EDS) mapping
+have revealed two nanoscale amorphous phases with different Tb atomic
+percentages distributed within the amorphous film. Exchange bias accompanied by
+bistable magneto-resistance states has been uncovered near room temperature by
+magnetization and magneto-transport measurements. The exchange anisotropy
+originates from the exchange interaction between the ferrimagnetic and
+ferromagnetic components corresponding to the two amorphous phases. This study
+provides a platform for exchange bias and magneto-resistance switching using
+single-layer amorphous ferrimagnetic thin films that require no epitaxial
+growth.",1512.06103v1
+2015-12-22,Initial state azimuthal anisotropies in small collision systems,"Strong multiparticle azimuthal correlations have recently been observed in
+high energy proton-nucleus collisions. While final state collective effects can
+be responsible for many of the observations, the domain structure in the
+classical color field of a high energy nucleus also naturally leads to such
+correlations. We describe recent calculations of the momentum space 2-particle
+cumulant azimuthal anisotropy coefficients v_n{2}, n=2,3,4 from fundamental
+representation Wilson line distributions describing the high energy nucleus. We
+find significant differences between Wilson lines from the MV model and from
+JIMWLK evolution. We also discuss the relation of this calculation to earlier
+work on the ridge correlation obtained in the ""glasma graph"" approximation, and
+to the ""color electric field domain model.""",1512.07209v1
+2015-12-23,Giant biquadratic interaction induced magnetic anisotropy in the iron-based superconductor AxFe2-ySe2,"The emergence of the electron-pocket only iron-based superconductor
+AxFe2-ySe2 (A = alkali metal) challenges the Fermi-surface nesting picture
+established in iron-pnictides. It was widely believed that magnetism is
+correlated with the superconductivity in AxFe2-ySe2. Unfortunately, the highly
+anisotropic exchange parameters and the disagreement between theoretical
+calculations and experimental results triggered a fierce debate on the nature
+of magnetism in AxFe2-ySe2. Here we find that the strong magnetic anisotropy is
+from the anisotropic biquadratic interaction. In order to accurately obtain the
+magnetic interaction parameters, we propose a universal method, which does not
+need including other high energy configurations as did in conventional energy
+mapping method. We show that our model successfully captures the magnetic
+interactions in AxFe2-ySe2 and correctly predicts the spin wave spectrum, in
+quantitative agreement with the experimental observation. These results suggest
+that the local moment picture, including the biquadratic term, can describe
+accurately the magnetic properties and spin excitations in AxFe2-ySe2, which
+sheds new light on the future study of the high-Tc iron-based superconductors.",1512.07327v1
+2015-12-23,Anisotropic hydrodynamics for conformal Gubser flow,"In this proceedings contribution, we review the exact solution of the
+anisotropic hydrodynamics equations for a system subject to Gubser flow. For
+this purpose, we use the leading-order anisotropic hydrodynamics equations
+which assume that the distribution function is ellipsoidally symmetric in
+local-rest-frame momentum. We then prove that the SO(3)_q symmetry in de Sitter
+space constrains the anisotropy tensor to be of spheroidal form with only one
+independent anisotropy parameter remaining. As a consequence, the exact
+solution reduces to the problem of solving two coupled non-linear differential
+equations. We show that, in the limit that the relaxation time goes to zero,
+one obtains Gubser's ideal hydrodynamic solution and, in the limit that the
+relaxation time goes to infinity, one obtains the exact free streaming solution
+obtained originally by Denicol et al. For finite relaxation time, we solve the
+equations numerically and compare to the exact solution of the
+relaxation-time-approximation Boltzmann equation subject to Gubser flow. Using
+this as our standard, we find that anisotropic hydrodynamics describes the
+spatio-temporal evolution of the system better than all currently known
+dissipative hydrodynamics approaches.",1512.07334v1
+2015-12-23,J/$ψ$ polarization measurements in p+p collisions at $\sqrt{s}$ = 200 and 500 GeV with the STAR experiment,"In these proceedings, measurements of J/psi polarization in p+p collisions at
+200 and 500 GeV via the dielectron decay channel at mid-rapidity with the STAR
+experiment are discussed. At 200 GeV the polarization parameter,
+$\lambda_{\theta}$, related to the polar anisotropy is obtained in the helicity
+frame as a function of transverse momentum, 2 < $p_{T}$ < 6 GeV/c, and compared
+to different model predictions. A new J/psi polarization measurement at 500 GeV
+extends the previous analysis to a wide transverse momentum range of 5 <
+$p_{T}$ < 16 GeV/c. Also, the polarization parameter related to the azimuthal
+anisotropy, $\lambda_{\phi}$, is extracted in addition to $\lambda_{\theta}$,
+in two reference frames: the helicity and Collins-Soper frames. This allows for
+the frame invariant parameter calculation vs $p_{T}$ in these two frames.",1512.07405v1
+2015-12-23,Low Energy Properties of the Kondo chain in the RKKY regime,"We study the Kondo chain in the regime of high spin concentration where the
+low energy physics is dominated by the Ruderman-Kittel-Kasuya-Yosida (RKKY)
+interaction. As has been recently shown (A. M. Tsvelik and O. M. Yevtushenko,
+Phys. Rev. Lett 115, 216402 (2015)), this model has two phases with drastically
+different transport properties depending on the anisotropy of the exchange
+interaction. In particular, the helical symmetry of the fermions is
+spontaneously broken when the anisotropy is of the easy plane type (EP). This
+leads to a parametrical suppression of the localization effects. In the present
+paper we substantially extend the previous theory, in particular, by analyzing
+a competition of forward- and backward- scattering, including into the theory
+short range electron interactions and calculating spin correlation functions.
+We discuss applicability of our theory and possible experiments which could
+support the theoretical findings.",1512.07495v1
+2016-01-07,Primordial power spectra for scalar perturbations in loop quantum cosmology,"We provide the power spectrum of small scalar perturbations propagating in an
+inflationary scenario within loop quantum cosmology. We consider the hybrid
+quantization approach applied to a Friedmann--Robertson--Walker spacetime with
+flat spatial sections coupled to a massive scalar field. We study the quantum
+dynamics of scalar perturbations on an effective background within this hybrid
+approach. We consider in our study adiabatic states of different orders. For
+them, we find that the hybrid quantization is in good agreement with the
+predictions of the dressed metric approach. We also propose an initial vacuum
+state for the perturbations, and compute the primordial and the anisotropy
+power spectrum in order to qualitatively compare with the current observations
+of Planck mission. We find that our vacuum state is in good agreement with
+them, showing a suppression of the power spectrum for large scale anisotropies.
+We compare with other choices already studied in the literature.",1601.01716v3
+2016-01-08,Current Control of Magnetic Anisotropy via Stress in a Ferromagnetic Metal Waveguide,"We demonstrate that in-plane charge current can effectively control the spin
+precession resonance in an Al2O3/CoFeB/Ta heterostructure. Brillouin Light
+Scattering (BLS) was used to detect the ferromagnetic resonance field under
+microwave excitation of spin waves at fixed frequencies. The current control of
+spin precession resonance originates from modification of the in-plane uniaxial
+magnetic anisotropy field H_k, which changes symmetrically with respect to the
+current direction. Numerical simulation suggests that the anisotropic stress
+introduced by Joule heating plays an important role in controlling H_k. These
+results provide new insights into current manipulation of magnetic properties
+and have broad implications for spintronic devices.",1601.02048v1
+2016-01-13,Investigation of Dosimetric Parameters of $^{192}$Ir MicroSelectron v2 HDR Brachytherapy Source Using EGSnrc Monte Carlo Code,"The $^{192}$Ir sources are widely used for high dose rate (HDR) brachytherapy
+treatments. The aim of this study is to simulate $^{192}$Ir MicroSelectron v2
+HDR brachytherapy source and calculate the air kerma strength, dose rate
+constant, radial dose function and anisotropy function established in the
+updated AAPM Task Group 43 protocol. The EGSnrc Monte Carlo (MC) code package
+is used to calculate these dosimetric parameters, including dose contribution
+from secondary electron source and also contribution of bremsstrahlung photons
+to air kerma strength. The Air kerma strength, dose rate constant and radial
+dose function while anisotropy functions for the distance greater than 0.5 cm
+away from the source center are in good agreement with previous published
+studies. Obtained value from MC simulation for air kerma strength is
+$9.762\times 10^{-8} \textrm{UBq}^{-1}$and dose rate constant is $1.108\pm
+0.13\%\textrm{cGyh}^{-1} \textrm{U}^{-1}$.",1601.03177v1
+2016-01-14,Statistical anisotropy from inflationary magnetogenesis,"Provided the quantum fluctuations are amplified in the presence of a
+classical gauge field configuration the resulting curvature perturbations
+exhibit a mild statistical anisotropy which should be sufficiently weak not to
+conflict with current observational data. The curvature power spectra induced
+by weakly anisotropic initial states are computed here for the first time when
+the electric and the magnetic gauge couplings evolve at different rates as it
+happens, for instance, in the relativistic theory of van der Waals
+interactions. After recovering the results valid for coincident gauge
+couplings, the constraints imposed by the isotropy and the homogeneity of the
+initial states are discussed. The obtained bounds turn out to be more stringent
+than naively expected and cannot be ignored when discussing the underlying
+magnetogenesis scenarios.",1601.03556v1
+2016-01-20,Origin of the mass splitting of elliptic anisotropy in a multiphase transport model,"The mass splitting of elliptic anisotropy ($v_2$) at low transverse momentum
+is considered as a hallmark of hydrodynamic collective flow. We investigate a
+multiphase transport (AMPT) model where the $v_2$ is mainly generated by an
+anisotropic escape mechanism, not of the hydrodynamic flow nature, and where
+mass splitting is also observed. We demonstrate that the $v_2$ mass splitting
+in AMPT is small right after hadronization (especially when resonance decays
+are included); the mass splitting mainly comes from hadronic rescatterings,
+even though their contribution to the overall charged hadron $v_2$ is small.
+These findings are qualitatively the same as those from hybrid models that
+combine hydrodynamics with a hadron cascade. We further show that there is no
+qualitative difference between heavy ion collisions and small system
+collisions. Our results indicate that the $v_2$ mass splitting is not a unique
+signature of hydrodynamic collective flow and thus cannot distinguish whether
+the elliptic flow is generated mainly from hydrodynamics or the anisotropic
+parton escape.",1601.05390v2
+2016-01-22,Determination of the Spin-Hall-Effect-Induced and the Wedged-Structure-Induced Spin Torque Efficiencies in Heterostructures with Perpendicular Magnetic Anisotropy,"We report that by measuring current-induced hysteresis loop shift versus
+in-plane bias magnetic field, the spin Hall effect (SHE) contribution of the
+current-induced effective field per current density, $\chi_{SHE}$, can be
+estimated for Pt and Ta-based magnetic heterostructures with perpendicular
+magnetic anisotropy (PMA). We apply this technique to a Pt-based sample with
+its ferromagnetic (FM) layer being wedged-deposited and discover an extra
+effective field contribution, $\chi_{Wedged}$, due to the asymmetric nature of
+the deposited FM layer. We confirm the correlation between $\chi_{Wedged}$ and
+the asymmetric depinning process in FM layer during magnetization switching by
+magneto-optical Kerr (MOKE) microscopy. These results indicate the possibility
+of engineering deterministic spin-orbit torque (SOT) switching by controlling
+the symmetry of domain expansion through the materials growth process.",1601.05854v1
+2016-01-27,Quasi-local conserved charges and spin transport in spin-$1$ integrable chains,"We consider the integrable one-dimensional spin-$1$ chain defined by the
+Zamolodchikov-Fateev (ZF) Hamiltonian. The latter is parametrized, analogously
+to the XXZ spin-$1/2$ model, by a continuous anisotropy parameter and at the
+isotropic point coincides with the well-known spin-$1$ Babujian-Takhtajan
+Hamiltonian. Following a procedure recently developed for the XXZ model, we
+explicitly construct a continuous family of quasi-local conserved operators for
+the periodic spin-$1$ ZF chain. Our construction is valid for a dense set of
+commensurate values of the anisotropy parameter in the gapless regime where the
+isotropic point is excluded. Using the Mazur inequality, we show that, as for
+the XXZ model, these quasi-local charges are enough to prove that the
+high-temperature spin Drude weight is non-vanishing in the thermodynamic limit,
+thus establishing ballistic spin transport at high temperature.",1601.07289v3
+2016-01-27,Dark Radiation and Inflationary Freedom after Planck 2015,"The simplest inflationary models predict a primordial power spectrum (PPS) of
+the curvature fluctuations that can be described by a power-law function that
+is nearly scale-invariant. It has been shown, however, that the low-multipole
+spectrum of the CMB anisotropies may hint the presence of some features in the
+shape of the scalar PPS, which could deviate from its canonical power-law form.
+We study the possible degeneracies of this non-standard PPS with the neutrino
+anisotropies, the neutrino masses, the effective number of relativistic species
+and a sterile neutrino or a thermal axion mass. The limits on these additional
+parameters are less constraining in a model with a non-standard PPS when only
+including the temperature auto-correlation spectrum measurements in the data
+analyses. The inclusion of the polarization spectra noticeably helps in
+reducing the degeneracies, leading to results that typically show no deviation
+from the $\Lambda$CDM model with a standard power-law PPS.",1601.07557v2
+2016-01-28,Composition-tuned magneto-optical Kerr effect in L10-MnxGa films with giant perpendicular anisotropy,"We report the large polar magnetooptical Kerr effect in L10-MnxGa epitaxial
+films with giant perpendicular magnetic anisotropy in a wide composition range.
+The Kerr rotation was enhanced by a factor of up to 10 by decreasing Mn atomic
+concentration, which most likely arises from the variation of the effective
+spin-orbit coupling strength, compensation effect of magnetic moments at
+different Mn atom sites, and overall strain. The Kerr ellipticity and the
+magnitude of the complex Kerr angle is found to have more complex
+composition-dependence that varies with the photon energy. These L10-MnxGa
+films show large Kerr rotation of up to 0.10o, high reflectivity of 35%-55% in
+a wide wavelength range of 400~850 nm, and giant magnetic anisotropic field of
+up to 210 kOe, making them an interesting material system for emerging
+spintronics and terahertz modulator applications.",1601.07939v4
+2016-01-30,On the Chiral imbalance and Weibel Instabilities,"We study the chiral-imbalance and the Weibel instabilities in presence of the
+quantum anomaly using the Berry-curvature modified kinetic equation. We argue
+that in many realistic situations, e.g. relativistic heavy-ion collisions, both
+the instabilities can occur simultaneously. The Weibel instability depends on
+the momentum anisotropy parameter $\xi$ and the angle ($\theta_n$) between the
+propagation vector and the anisotropy direction. It has maximum growth rate at
+$\theta_n=0$ while $\theta_n=\pi/2$ corresponds to a damping. On the other hand
+the pure chiral-imbalance instability occurs in an isotropic plasma and depends
+on difference between the chiral chemical potentials of right and left-handed
+particles. It is shown that when $\theta_n=0$, only for a very small values of
+the anisotropic parameter $\xi\sim \xi_c$, growth rates of the both
+instabilities are comparable. For the cases $\xi_c<\xi\ll1$, $\xi\approx 1$ or
+$\xi \geq 1$ at $\theta_n=0$, the Weibel modes dominate over the
+chiral-imbalance instability if $\mu_5/T\leq1$. However, when $\mu_5/T\geq1$,
+it is possible to have dominance of the chiral-imbalance modes at certain
+values of $\theta_n$ for an arbitrary $\xi$.",1602.00111v1
+2016-02-04,Magnetic anisotropy of the single-crystalline ferromagnetic insulator Cr2Ge2Te6,"Cr2Ge2Te6 (CGT), a layered ferromagnetic insulator, has attracted a great
+deal of interest recently owing to its potential for integration with Dirac
+materials to realize the quantum anomalous Hall effect (QAHE) and to develop
+novel spintronics devices. Here, we study the uniaxial magnetic anisotropy
+energy of single-crystalline CGT and determine that the magnetic easy axis is
+directed along the c-axis in its ferromagnetic phase. In addition, CGT is an
+insulator below the Curie temperature. These properties make CGT a potentially
+promising candidate substrate for integration with topological insulators for
+the realization of the high-temperature QAHE.",1602.01556v1
+2016-02-16,The dissipation tensor $\varepsilon_{ij}$ in wall turbulence,"The paper investigates the dissipation tensor $\varepsilon_{ij}$ in wall
+turbulence. Available DNS data are examined to illustrate the differences in
+the anisotropy of the dissipation tensor $\varepsilon_{ij}$ with respect to the
+anisotropy of the Reynolds-stresses $r_{ij}$. The budgets of the transport
+equations of the dissipation tensor $\varepsilon_{ij}$ are studied using novel
+DNS data of low-Reynolds-number turbulent plane channel flow with spatial
+resolution sufficiently fine to accurately determine the correlations of
+products of 2-derivatives of fluctuating velocities $u_i'$ and pressure $p'$
+which appear in various terms. Finally, the influence of the Reynolds number on
+the diagonal components of $\varepsilon_{ij}$ ($\varepsilon_{xx}$,
+$\varepsilon_{yy}$, $\varepsilon_{zz}$) and on the various terms in their
+transport equations is studied using available DNS data of Vreman and Kuerten
+(Phys. Fluids 26 (2014) 085103).",1602.05022v3
+2016-02-19,Optical anisotropy of the Jeff = 1/2 Mott insulator Sr2IrO4,"We report the complex dielectric function along and perpendicular to the IrO2
+planes in the layered perovskite Sr2IrO4 determined by spectroscopic
+ellipsometry in the spectral range from 12 meV to 6 eV. Thin high quality
+single crystals were stacked to measure the c-axis optical conductivity. In the
+phonon response we identified 10 infrared-active modes polarized within the
+basal plane and only four modes polarized along the c-axis, in full agreement
+with first-principle lattice dynamics calculations. We also observed a strong
+optical anisotropy in the near-infrared spectra arising from direct transitions
+between Ir 5d t2g Jeff = 1/2 and Jeff = 3/2 bands, which transition probability
+is highly suppressed for light polarized along the c-axis. The spectra are
+analyzed and discussed in terms of relativistic LSDA+U band structure
+calculations.",1602.06090v1
+2016-02-19,Magnetic anisotropy of large floating-zone-grown single-crystals of SrRuO3,"SrRuO3 is a highly interesting material due to its anomalous-metal properties
+related with ferromagnetism and its relevance as conductive perovskite layer or
+substrate in heterostructure devices. We have used optical floating zone
+technique in an infrared image furnace to grow large single crystals of SrRuO3
+with volumes attaining several hundred mm3. Crystals obtained for optimized
+growth parameters exhibit a high ferromagnetic Curie temperature of 165 K and a
+low-temperature magnetization of 1.6 muB at a magnetic field of 6 T. The high
+quality of the crystals is further documented by large residual resistance
+ratios of 75 and by crystal structure and chemical analyzes. With these
+crystals the magnetic anisotropy could be determined.",1602.06171v2
+2016-02-22,Critical behaviour of anisotropic magnets with quenched disorder: replica symmetry breaking studied by operator product expansion,"We study critical behaviour of disordered magnets near four dimensions. We
+consider the system with explicit cubic anisotropy and scalar disorder and that
+with random direction of anisotropy axis. The quenched disorder is taken into
+account by replica method. Using the method of operator product expansion, we
+derive in the first order to $\epsilon$ approximation the renormalization group
+equations taking into account possible replica symmetry breaking.",1602.06789v9
+2016-02-23,Zero temperature non-plateau magnetization and magnetocaloric effect in an Ising-XYZ diamond chain structure,"Zero temperature non-plateau magnetization is a peculiar property of a
+quantum spin chain and it sometimes appears due to different gyromagnetic
+factors. In this study, we illustrate a quite unusual nonplateau magnetization
+property driven by XY-anisotropy in an Ising-XYZ diamond chain. Two particles
+with spin-1/2 are bonded by XYZ coupling and they are responsible for the
+emergence of non-plateau magnetization. These two quantum operator spins are
+bonded to two nodal Ising spins and this process is repeated infinitely to
+yield a diamond chain structure. Due to the non-plateau magnetization property,
+we focus our discussion on the magnetocaloric effect of this model by
+presenting the isentropic curves and the Gruneisen parameters, as well as
+showing the regions where the model exhibits an efficient magnetocaloric
+effect. Due to the existence of two phases located very close to each other,
+the strong XY-anisotropy exhibits a particular behavior with a magnetocaloric
+effect, with a wider interval in the magnetic field, where the magnetocaloric
+effect is efficient.",1602.07279v4
+2016-02-25,Thermal simulation of magnetization reversals for size-distributed assemblies of core-shell exchange biased nanoparticles,"A temperature dependent coherent magnetization reversal model is proposed for
+size-distributed assemblies of ferromagnetic nanoparticles and
+ferromagnetic-antiferromagnetic core-shell nanoparticles. The nanoparticles are
+assumed to be of uniaxial anisotropy and all aligned along their easy axis. The
+thermal dependence is included by considering thermal fluctuations, implemented
+via the N\'eel-Arrhenius theory. Thermal and angular dependence of
+magnetization reversal loops, coercive field and exchange-bias field are
+obtained, showing that F-AF size-distributed exchange-coupled nanoparticles
+exhibit temperature-dependent asymmetric magnetization reversal. Also,
+non-monotonic evolutions of He and Hc with T are demonstrated. The angular
+dependence of Hc with T exhibits a complex behavior, with the presence of an
+apex, whose position and amplitude are strongly T dependent. The angular
+dependence of He with T exhibits complex behaviors, which depends on the AF
+anisotropy and exchange coupling. The resulting angular behavior demonstrates
+the key role of the size distribution and temperature in the magnetic response
+of nanoparticles.",1602.07877v2
+2016-02-25,Various Time-Scales of Relaxation,"Via gauge-gravity duality, relaxation of far-from-equilibrium initial states
+in a strongly coupled gauge theory has been investigated. In the system we
+consider in this paper there are two ways where the state under study can
+deviate from its equilibrium: anisotropic pressure and time-dependent
+expectation value of a scalar operator with \Delta=3. In the gravity theory,
+this system corresponds to Einstein's general relativity with a non-trivial
+metric, including the anisotropy function, coupled to a massive scalar matter
+field. We study the effect of different initial configurations for scalar field
+and anisotropy function on physical processes such as thermalization, i.e. time
+evolution of event horizon, equilibration of the expectation value of scalar
+operator and isotropization. We also discuss time ordering of these
+time-scales.",1602.07903v2
+2016-02-25,Dark matter component decaying after recombination: lensing constraints with Planck data,"It has been recently suggested~\cite{Berezhiani:2015yta} that emerging
+tension between cosmological parameter values derived in high-redshift (CMB
+anisotropy) and low-redshift (cluster counts, Hubble constant) measurements can
+be reconciled in a model which contains subdominant fraction of dark matter
+decaying after recombination. We check the model against the CMB Planck data.
+We find that lensing of the CMB anisotropies by the large-scale structure gives
+strong extra constraints on this model, limiting the fraction as $F<8\%$ at
+2\,$\sigma$ confidence level. However, investigating the combined data set of
+CMB and conflicting low-$z$ measurements, we obtain that the model with
+$F\approx2\!-\!5$\% exhibits better fit (by 1.5-3\,$\sigma$ depending on the
+lensing priors) compared to that of the concordance $\Lambda$CDM cosmological
+model.",1602.08121v2
+2016-03-08,Searching for Cosmological Preferred Axis using cosmographic approach,"Recent released Planck data and other astronomical observations show that the
+universe may be anisotropic on large scales. This hints a cosmological
+privileged axis in our anisotropic expanding universe. This paper proceeds a
+modified redshift in anisotropic cosmological model as $
+1+\tilde{z}(t,\hat{\textbf{p}})=\frac{a(t_{0)}}{a(t)}(1-A(\hat{\textbf{n}}.\hat{\textbf{p}}))$
+(where $A$ is the magnitude of anisotropy ,$\hat{\textbf{n}}$ is the direction
+of privileged axis, and $\hat{\textbf{p}}$ is the direction of each SNe Ia
+sample to galactic coordinates) along with anisotropic parameter
+$\delta=\frac{A(\hat{\textbf{n}}.\hat{\textbf{p}})}{1+A(\hat{\textbf{n}}.\hat{\textbf{p}})}$.
+The luminosity distance is expanded with model-independent cosmographic
+parameters as a function of modified redshift $\tilde{z}$. As the
+transformation matrix $M(n\times n)$ is obtained to convert the Taylor series
+coefficients of isotropic luminosity distance to corresponding anisotropic
+parameters. These results culminate the magnitude of anisotropy about $\mid
+A\mid \simeq 10^{-3}$ and the direction of preferred axis as
+$(l,b)=(297^{-34}_{+34},3^{-28}_{+28})$, which are consistent with other
+studies in $1-\sigma$ confidence level.",1603.02659v2
+2016-03-09,Evolution of perpendicular magnetized tunnel junctions upon annealing,"We study the evolution of perpendicularly magnetized tunnel junctions under
+300 to 400 $^{\circ}$C annealing. The hysteresis loops do not evolve much
+during annealing and they are not informative of the underlying structural
+evolutions. These evolutions are better revealed by the frequencies of the
+ferromagnetic resonance eigenmodes of the tunnel junction. Their modeling
+provides the exchange couplings and the layers' anisotropies within the stack
+which can serve as a diagnosis of the tunnel junction state after each
+annealing step. The anisotropies of the two CoFeB-based parts and the two
+Co/Pt-based parts of the tunnel junction decay at different rates during
+annealing. The ferromagnet exchange coupling through the texture-breaking Ta
+layer fails above 375$^{\circ}$C. The Ru spacer meant to promote a synthetic
+antiferromagnet behavior is also insufficiently robust to annealing. Based on
+these evolutions we propose optimization routes for the next generation tunnel
+junctions.",1603.02824v1
+2016-03-11,Measurement of the $B_{1g}$ and $B_{2g}$ components of the elastoresistivity tensor for tetragonal materials via transverse resistivity configurations,"The elastoresistivity tensor $m_{ij,kl}$ relates changes in resistivity to
+strains experienced by a material. As a fourth-rank tensor, it contains
+considerably more information about the material than the simpler (second-rank)
+resistivity tensor; in particular, for a tetragonal material, the $B_{1g}$ and
+$B_{2g}$ components of the elastoresistivity tensor ($m_{xx,xx}-m_{xx,yy}$ and
+$2m_{xy,xy}$, respectively) can be related to its nematic susceptibility.
+Previous experimental probes of this quantity have focused exclusively on
+differential longitudinal elastoresistance measurements, which determine the
+induced resistivity anisotropy arising from anisotropic in-plane strain based
+on the difference of two longitudinal resistivity measurements. Here we
+describe a complementary technique based on \textit{transverse}
+elastoresistance measurements. This new approach is advantageous because it
+directly determines the strain-induced resistivity anisotropy from a single
+transverse measurement. To demonstrate the efficacy of this new experimental
+protocol, we present transverse elastoresistance measurements of the
+$2m_{xy,xy}$ elastoresistivity coefficient of BaFe$_2$As$_2$, a representative
+iron-pnictide that has previously been characterized via differential
+longitudinal elastoresistance measurements.",1603.03537v1
+2016-03-11,Effects of anisotropy on interacting ghost dark energy in Brans-Dicke theories,"By interacting ghost dark energy (ghost DE) in the framework of Brans-Dicke
+theory, a spatially homogeneous and anisotropic Bianchi type I Universe has
+been studied. For this purpose, we use the squared sound speed $c_s^2$ whose
+sign determines the stability of the model. As well as we probe observational
+constraints on the ghost dark energy models as the unification of dark matter
+and dark energy by using the latest observational data. In order to do so, we
+focus on observational determinations of the Hubble expansion rate (namely, the
+expansion history) $H(z)$. After that we evaluate the evolution of the growth
+of perturbations in the linear regime for both ghost DE and Brans-Dicke theory
+and compare the results with standard FRW and $\Lambda$CDM models. We display
+the effects of the anisotropy on the evolutionary behavior the ghost DE models
+where the growth rate is higher in this models. Eventually the growth factor
+for the $\Lambda$CDM Universe will always fall behind the ghost DE models in an
+anisotropic Universe",1603.03681v2
+2016-03-15,"Interplay of Quantum Size Effect, Anisotropy and Surface Stress Shapes the Instability of Thin Metal Films","Morphological instability of a planar surface ([111], [011], or [001]) of an
+ultra-thin metal film is studied in a parameter space formed by three major
+effects (the quantum size effect, the surface energy anisotropy and the surface
+stress) that influence a film dewetting. The analysis is based on the extended
+Mullins equation, where the effects are cast as functions of the film
+thickness. The formulation of the quantum size effect (Z. Zhang et al., PRL 80,
+5381 (1998)) includes the oscillation of the surface energy with thickness
+caused by electrons confinement. By systematically comparing the effects, their
+contributions into the overall stability (or instability) is highlighted.",1603.04675v3
+2016-03-15,Ordering in rolled-up single-walled ferromagnetic nanomembranes,"Magnetization of soft-ferromagnetic nano- and microtubes of nanometer-thin
+walls (a single-widening rolled-up nanomembranes) is theoretically studied
+using analytical and numerical approaches including different stress-induced
+anisotropies. Within the analytical study, we consider magnetostatic effects
+qualitatively, with an effective anisotropy, while they are fully treated in
+the micromagnetic simulations (limited to the tubes of submicrometer diameters
+however). Basic types of the periodic ordering have been established and their
+presence in nanotubes of polycrystalline Permalloy and cobalt has been verified
+within the simulations. The domain structure is basically determined by a
+material-deposition-induced helical stress or a cooling-induced axial stress
+via the volume magnetostriction while it is influenced by the distribution of
+magnetic charges as well. Also, it is dependent on the initial state of the
+magnetization process.",1603.04883v2
+2016-03-16,Highly anisotropic and two-fold symmetric superconducting gap in nematically ordered FeSe$_{0.93}$S$_{0.07}$,"FeSe exhibits a novel ground state in which superconductivity coexists with a
+nematic order in the absence of any long-range magnetic order. Here we report
+an angle-resolved photoemission study on the superconducting gap structure in
+the nematic state of FeSe$_{0.93}$S$_{0.07}$, without the complication caused
+by Fermi surface reconstruction induced by magnetic order. We found that the
+superconducting gap shows a pronounced 2-fold anisotropy around the elliptical
+hole pocket near the Z point of the Brillouin zone, with gap minima at the
+endpoints of its major axis, while no detectable gap was observed around the
+zone center and zone corner. The large anisotropy and nodal gap distribution
+demonstrate the substantial effects of the nematicity on the superconductivity,
+and thus put strong constraints on the current theories.",1603.05219v1
+2016-03-17,Anisotropic Ginzburg-Landau scaling of Hc2 and transport properties of 112-type Ca0.8La0.2Fe0.98Co0.02As2 single crystal,"High-quality single crystal of Ca0.8La0.2Fe0.98Co0.02As2 has been
+successfully synthesized using a self-flux method. The magnetization
+measurement reveals a second peak effect and high critical current density
+exceeding 2*10^6 A/cm2 at 5 K(self-field). The upper critical field anisotropy
+was systematically studied by measuring the electrical resistivity under
+various magnetic fields and angles. The angle dependent magnetoresistance, by
+choosing an appropriate anisotropy parameter within the framework of the
+anisotropic Ginzburg Landau (AGL) theory, can be scaled onto one single curve.
+In the normal state, the negative Hall coefficient shows strong but
+nonmonotonic T-dependence through a minimum at 175 K. Moreover, it is shown
+that the magnetoresistance apparently violates the semiclassical Kohler's rule
+below 175 K but can be well scaled by the Hall angle instead. This suggests
+either the change of carriers with T or the exotic anisotropic scattering in
+the system.",1603.05392v1
+2016-03-18,Electric-field dependent g-factor anisotropy in Ge-Si core-shell nanowire quantum dots,"We present angle-dependent measurements of the effective g-factor g* in a
+Ge-Si core-shell nanowire quantum dot. g* is found to be maximum when the
+magnetic field is pointing perpendicular to both the nanowire and the electric
+field induced by local gates. Alignment of the magnetic field with the electric
+field reduces g* significantly. g* is almost completely quenched when the
+magnetic field is aligned with the nanowire axis. These findings confirm recent
+calculations, where the obtained anisotropy is attributed to a Rashba-type
+spin-orbit interaction induced by heavy-hole light-hole mixing. In principle,
+this facilitates manipulation of spin-orbit qubits by means of a continuous
+high-frequency electric field.",1603.05877v1
+2016-03-21,Selection of direction of the ordered moments in Na$_2$IrO$_3$ and $α-$RuCl$_3$,"The magnetic orders in Na$_2$IrO$_3$ and $\alpha-$RuCl$_3$, honeycomb systems
+with strong spin-orbit coupling and correlations, have been recently described
+by models with the dominant Kitaev interactions. In this work we discuss how
+the orientation of magnetic order parameter is selected in this class of
+models. We show that while the order-by-disorder mechanism in the models with
+solely Kitaev anisotropies always select cubic axes as easy axes for magnetic
+ordering, the additional effect of other small bond-dependent anisotropies,
+such as, e.g., $\Gamma$-terms, lead to a deviation of the order parameter from
+the cubic directions. We show that both the zigzag ground state and the
+face-diagonal orientation of magnetic moments in Na$_2$IrO$_3$ can be obtained
+within the $J_1-K_1-J_2-K_2-J_3$ model in the presence of perturbatively small
+$\Gamma$-terms. We also show that the zigzag phase found in the nearest
+neighbor Kitaev-Heisenberg model, relevant for $\alpha-$RuCl$_3$, has some
+stability against the $\Gamma$-term.",1603.06487v2
+2016-03-24,Interplay of Coulomb interaction and spin-orbit coupling,"We employ the Gutzwiller variational approach to investigate the interplay of
+Coulomb interaction and spin-orbit coupling in a three-orbital Hubbard model.
+Already in the paramagnetic phase we find a substantial renormalization of the
+spin-orbit coupling that enters the effective single-particle Hamiltonian for
+the quasi-particles. Only close to half band-filling and for sizable Coulomb
+interaction we observe clear signatures of Hund's atomic rules for spin,
+orbital, and total angular momentum. For a finite local Hund's-rule exchange
+interaction we find a ferromagnetically ordered state. The spin-orbit coupling
+considerably reduces the size of the ordered moment, it generates a small
+ordered orbital moment, and it induces a magnetic anisotropy. To investigate
+the magnetic anisotropy energy, we use an external magnetic field that tilts
+the magnetic moment away from the easy axis $(1,1,1)$.",1603.07544v3
+2016-04-07,Angular distributions in $J/ψ\to p\bar{p}π^{0}(η)$ decays,"The differential decay rates of the processes $J/\psi\to p\bar{p}\pi^{0}$ and
+$J/\psi\to p\bar{p}\eta$ close to the $p\bar{p}$ threshold are calculated with
+the help of the $N\bar{N}$ optical potential. The same calculations are made
+for the decays of $\psi(2S)$. We use the potential which has been suggested to
+fit the cross sections of $N\bar{N}$ scattering together with $N\bar{N}$ and
+six pion production in $e^{+}e^{-}$ annihilation close to the $p\bar{p}$
+threshold. The $p\bar{p}$ invariant mass spectra is in agreement with the
+available experimental data. The anisotropy of the angular distributions, which
+appears due to the tensor forces in the $N\bar{N}$ interaction, is predicted
+close to the $p\bar{p}$ threshold. This anisotropy is large enough to be
+investigated experimentally. Such measurements would allow one to check the
+accuracy of the model of $N\bar{N}$ interaction.",1604.01951v1
+2016-04-04,Two-dimensional Hybrid Simulations of Kinetic Plasma Turbulence: Current and Vorticity vs Proton Temperature,"Proton temperature anisotropies between the directions parallel and
+perpendicular to the mean magnetic field are usually observed in the solar wind
+plasma. Here, we employ a high-resolution hybrid particle-in-cell simulation in
+order to investigate the relation between spatial properties of the proton
+temperature and the peaks in the current density and in the flow vorticity. Our
+results indicate that, although regions where the proton temperature is
+enhanced and temperature anisotropies are larger correspond approximately to
+regions where many thin current sheets form, no firm quantitative evidence
+supports the idea of a direct causality between the two phenomena. On the other
+hand, quite a clear correlation between the behavior of the proton temperature
+and the out-of-plane vorticity is obtained.",1604.03040v1
+2016-04-21,Anisotropy and interaction effects of strongly strained SrIrO3 thin films,"Magneto-transport properties of SrIrO$_3$ thin films epitaxially grown on
+SrTiO$_3$, using reactive RF sputtering, are investigated. A large anisotropy
+between the in-plane and the out-of-plane resistivities is found, as well as a
+signature of the substrate cubic to tetragonal transition. Both observations
+result from the structural distortion associated to the epitaxial strain. The
+low-temperature and field dependences of the Hall number are interpreted as due
+to the contribution of Coulomb interactions to weak localization, evidencing
+the strong correlations in this material. The introduction of a contribution
+from magnetic scatters, in the analysis of magnetoconductance in the weakly
+localized regime, is proposed as an alternative to an anomalously large
+temperature dependence of the Land\'{e} coefficient.",1604.06390v2
+2016-04-25,Non-Gaussian eccentricity fluctuations,"We study the fluctuations of the anisotropy of the energy density profile
+created in a high-energy collision at the LHC. We show that the anisotropy in
+harmonic $n$ has generic non-Gaussian fluctuations. We argue that these
+non-Gaussianities have a universal character for small systems such as p+Pb
+collisions, but not for large systems such as Pb+Pb collisions where they
+depend on the underlying non-Gaussian statistics of the initial density
+profile. We generalize expressions for the eccentricity cumulants
+$\varepsilon_2\{4\}$ and $\varepsilon_3\{4\}$ previously obtained within the
+independent-source model to a general fluctuating initial density profile.",1604.07230v2
+2016-04-28,"Magnetization Saturation Process in the Magnonic Anti-dot Structures Based on (Ga,Mn)As: A Magnetometric Study","Applicability of dilute magnetic semiconductors (DMS) in electronic devices
+relies upon the understanding and control of their magnetic anisotropy. This
+paper explores one of the ways in engineering magnetic anisotropy in epitaxial
+layers of DMS by forming them into magnonic structures. For this purpose the
+canonical ferromagnetic DMS, namely (Ga,Mn)As, is employed. The anti-dot
+systems based on (Ga,Mn)As layers of various thicknesses are fabricated with
+focused ion beam apparatus and studied by means of microscopy as well as
+magnetometry. The magnetometric data - collected along two nonequivalent
+in-plane crystallographic directions of (Ga,Mn)As: [110] and [1-10] - shows the
+effect of structuring on high-field magnetization process, whereas no
+significant change of the width of hysteresis loop in anti-dot samples is
+observed.",1604.08607v1
+2016-04-29,Polarization-selective branching of stop gaps in three-dimensional photonic crystals,"We study the direction- and wavelength-dependent polarization anisotropy in
+light scattering at the air-photonic crystal interface as a function of angle
+of incidence for TE and TM polarized light. This is done using optical
+reflectivity measurements at high-symmetry points in the Brillouin zone of a
+three-dimensional photonic crystal with fcc symmetry. Polarized reflectivity
+measurements indicate the presence of stop gap branching for TE polarization,
+which is absent for TM polarization till the Brewster angle at K point. In
+contrast, stop gap branching is present for both TE and TM polarizations at W
+point due to the intricate mixing of crystal planes. This characteristic
+behavior signifies the inevitable role of energy exchange in the stop gap
+branching. The measured polarization anisotropy shows a prominent shift in the
+Brewster angle for on-resonance wavelength as compared to the off-resonance
+along both K and W points, and that, in accordance with theory. Our results
+have implications in polarization-induced light scattering in sub-wavelength
+photonic structures like plasmonic crystals, and meta-materials.",1604.08889v1
+2016-05-04,Quantum domain walls induce incommensurate supersolid phase on the anisotropic triangular lattice,"We investigate the extended hard-core Bose-Hubbard model on the triangular
+lattice as a function of spatial anisotropy with respect to both tunneling and
+nearest-neighbor interaction strength. At half-filling the system can be tuned
+from decoupled one-dimensional chains to a two-dimensional solid phase with
+alternating density order by adjusting the anisotropic coupling. At
+intermediate anisotropy, however, frustration effects dominate and an
+incommensurate supersolid phase emerges, which is characterized by
+incommensurate density order as well as an anisotropic superfluid density. We
+demonstrate that this intermediate phase results from the proliferation of
+topological defects in the form of quantum bosonic domain walls. Accordingly,
+the structure factor has peaks at wave vectors, which are linearly related to
+the number of domain walls in a finite system in agreement with extensive
+quantum Monte Carlo simulations. We discuss possible connections with the
+supersolid behavior in the high-temperature superconducting striped phase.",1605.01237v2
+2016-05-08,Cage effect in supercooled molecular liquids: local anisotropies and collective solid-like response,"Both local geometry and collective, extended excitations drive the moves of a
+particle in the cage of its neighbours in dense liquids. The strength of their
+influence is investigated by Molecular Dynamics simulations of a supercooled
+liquid of fully-flexible trimers with semirigid or rigid bonds. The rattling in
+the cage is investigated on different length scales. First, the rattling
+anisotropy due to local order is characterized by two order parameters sensing
+the monomers succeeding or failing to escape from the cage. Then, the
+collective response of the surroundings excited by the monomer-monomer
+collisions is considered. The collective response is initially restricted to
+the nearest neighbours of the colliding particle by a Voronoi analysis
+revealing elastic contributions. Then, the long-range excitation of the
+farthest neighbours is scrutinised by searching spatially-extended correlations
+between the simultaneous fast displacements of the caged particle and the
+surroundings. It is found that the longitudinal component has stronger spatial
+modulation than the transverse one with wavelength of about one particle
+diameter, in close resemblance with experimental findings on colloids. It is
+concluded that the cage rattling is largely affected by solid-like extended
+modes.",1605.02318v1
+2016-05-11,Quasi-matter bounce and inflation in the light of the CSL model,"The Continuous Spontaneous Localization (CSL) model has been proposed as a
+possible solution to the quantum measurement problem by modifying the
+Schr\""{o}dinger equation. In this work, we apply the CSL model to two
+cosmological models of the early Universe: the matter bounce scenario and slow
+roll inflation. In particular, we focus on the generation of the classical
+primordial inhomogeneities and anisotropies that arise from the dynamical
+evolution, provided by the CSL mechanism, of the quantum state associated to
+the quantum fields. In each case, we obtained a prediction for the shape and
+the parameters characterizing the primordial spectra (scalar and tensor), i.e.
+the amplitude, the spectral index and the tensor-to-scalar ratio. We found that
+there exist CSL parameter values, allowed by other non-cosmological
+experiments, for which our predictions for the angular power spectrum of the
+CMB temperature anisotropy are consistent with the best fit canonical model to
+the latest data released by the Planck Collaboration.",1605.03632v2
+2016-05-14,Highly anisotropic electronic transport properties of monolayer and bilayer phosphorene from first principles,"The intrinsic carrier transport dynamics in phosphorene is theoretically
+examined. Utilizing a density functional theory treatment, the low-field
+mobility and the saturation velocity are characterized for both electrons and
+holes in the monolayer and bilayer structures. The analysis clearly elucidates
+the crystal orientation dependence manifested through the anisotropic band
+structure and the carrier-phonon scattering rates. In the monolayer, the hole
+mobility in the armchair direction is estimated to be approximately five times
+larger than in the zigzag direction at room temperature (460 cm$^2$/Vs vs. 90
+cm$^2$/Vs). The bilayer transport, on the other hand, exhibits a more modest
+anisotropy with substantially higher mobilities (1610 cm$^2$/Vs and 760
+cm$^2$/Vs, respectively). The calculations on the conduction-band electrons
+indicate a comparable dependence while the characteristic values are generally
+smaller by about a factor of two. The variation in the saturation velocity is
+found to be less pronounced. With the anticipated superior performance and the
+diminished anisotropy, few-layer phosphorene offers a promising opportunity
+particularly in p-type applications.",1605.04377v1
+2016-05-17,Quantum Spin Liquid in a Breathing Kagome Lattice,"Motivated by recent experiments on the vanadium oxyfluoride material DQVOF,
+we examine possible spin liquid phases on a breathing kagome lattice of S=1/2
+spins. By performing a projective symmetry group analysis, we determine the
+possible phases for both fermionic and bosonic $\mathbb{Z}_2$ spin liquids on
+this lattice, and establish the correspondence between the two. The nature of
+the ground state of the Heisenberg model on the isotropic kagome lattice is a
+hotly debated topic, with both $\mathbb{Z}_2$ and U(1) spin liquids argued to
+be plausible ground states. Using variational Monte Carlo techniques, we show
+that a gapped $\mathbb{Z}_2$ spin liquid emerges as the clear ground state in
+the presence of this breathing anisotropy. Our results suggest that the
+breathing anisotropy helps to stabilize this spin liquid ground state, which
+may aid us in understanding the results of experiments and help to direct
+future numerical studies on these systems.",1605.05322v1
+2016-05-18,A Framework for FFT-based Homogenization on Anisotropic Lattices,"In order to take structural anisotropies of a given composite and different
+shapes of its unit cell into account, we generalize the Basic Scheme in
+Homogenization by Moulinec and Suquet to arbitrary sampling lattices and
+tilings of the d-dimensional Euclidean space. Employing a Fourier transform on
+arbitrary lattices, which generate sampling patterns in the unit cell of
+interest, we derive a generalization of this scheme. In several cases, this
+Fourier transform is of lower dimension than the space itself; for many
+lattices it even reduces to a one-dimensional Fourier transform having the same
+leading coefficient as the fastest Fourier transform implementation available.
+We illustrate the generalized Basic Scheme on an anisotropic laminate and a
+generalized ellipsoidal Hashin structure. For both we derive an analytical
+solution to the elasticity problem, in two- and three dimensions, respectively.
+We then illustrate the possibilities of choosing a pattern. Compared to
+classical grids this introduces both a reduction of computation time and a
+reduced error of the numerical method. It also allows for anisotropic
+subsampling, i.e. choosing a sub lattice of a pixel or voxel grid based on
+anisotropy information of the material at hand.",1605.05712v2
+2016-05-25,Squeeze expulsion in grain size segregation,"Grain segregation occurs under various conditions, such as vibration, shear
+and mixing. In the gravity-driven shear flow, size segregation is triggered by
+the percolation of small particles through the opened voids (kinetic sieving),
+and large particles are accumulated in the upper layer. One hypothesis for the
+upward migration of large particles is the squeeze expulsion mechanism, which
+remains yet ambiguous due to limited evidences from either physical or
+numerical experiments. Here we show statistically how the percolation of small
+particles facilitates the upward movement of large particles. We found that in
+large particles, the mechanical anisotropy (strong force network) coincides
+with the geometric anisotropy (contact network), which indicates squeeze, and
+the connectivity of large particles is much higher when they are squeezed
+through small particles. The presence of small particles filling the voids
+hinders the downward movements and provides dynamic steps for the climbing
+large particles. Furthermore, increasing the coefficient of friction promotes
+rotation and empowers more large particles to reach the top layer, implying
+that the climbing particles tend to rotate relative to their neighbors. Our
+findings of the microstructure and movement pattern of individual particles add
+new evidences to the mechanism of squeeze expulsion and provide new perspective
+for the study of segregation.",1605.07994v1
+2016-05-26,Handling magnetic anisotropy and dynamic magnetic response of ferromagnetic multilayers in flexible substrates,"We investigate the dynamic magnetic response of ferromagnetic flexible
+NiFe/Ta and FeCuNbSiB/Ta multilayers under external stress. We explore the
+possibility of handling magnetic anisotropy and dynamic magnetic response of
+flexible magnetostrictive nanostructures. We quantify the sensitivity of the
+multilayers under external stress by calculating the ratio $|\Delta
+\textrm{MI}|/|\Delta \bar{\sigma}|$ and show that considerable values can be
+reached by tuning the magnetic field, frequency, magnetostriction constant, and
+external stress. The results reveal possibilities of application of flexible
+magnetostrictive multilayers under external stress and place them as very
+attractive candidates as element sensor for the development of sensitive smart
+touch sensors.",1605.08193v2
+2016-05-29,Universality of fractal to non-fractal morphological transitions in stochastic growth processes,"Stochastic growth processes give rise to diverse intricate structures
+everywhere and across all scales in nature. Despite the seemingly unrelated
+complex phenomena at their origin, the Laplacian growth theory has succeeded in
+unifying their treatment under one framework, nonetheless, important aspects
+regarding fractal to non-fractal morphological transitions, coming from the
+competition between screening and anisotropy-driven forces, still lacks a
+comprehensive description. Here we provide such unified description,
+encompassing all the known characteristics for these transitions, as well as
+new universal ones, through the statistical mix of basic models of
+particle-aggregation and the introduction of a phenomenological physically
+meaningful dimensionality function, that characterizes the fractality of a
+symmetry-breaking process induced by a generalized anisotropy-driven force. We
+also show that the generalized Laplacian growth (dielectric breakdown) model
+belongs to this class. Moreover, our results provide important insights on the
+dynamical origins of mono/multi-fractality in pattern formation, that generally
+occur in far-from-equilibrium processes.",1605.08967v1
+2016-05-31,Anisotropy-assisted non-scattering coherent absorption of surface plasmon-polaritons,"The ability to control propagation of electromagnetic guided modes lies at
+the heart of integrated nanophotonics. Surface plasmon-polaritons are a class
+of guided modes which can be employed in integrated optical systems. Here, we
+present a theoretical design of a coherent surface plasmon absorber which can
+perfectly harvest energy of coherently incident surface plasmons without
+parasitic scattering into free space modes. Excitation of free space modes
+which usually accompanies scattering of a surface plasmon by an interface
+boundary is avoided due to specially tailored anisotropy of the absorber. The
+concept of coherent SPP absorber is analyzed numerically for spatially
+non-uniform and finite-size structures. We believe that our results will be
+important for the development of integrated nanoplasmonic systems.",1606.00027v1
+2016-06-02,"Bicollinear Antiferromagnetic Order, Monoclinic Distortion, and Reversed Resistivity Anisotropy in FeTe as a Result of Spin-Lattice Coupling","The bicollinear antiferromagnetic order experimentally observed in FeTe is
+shown to be stabilized by the coupling $\tilde g_{12}$ between monoclinic
+lattice distortions and the spin-nematic order parameter with $B_{\rm 2g}$
+symmetry, within a three-orbital spin-fermion model studied with Monte Carlo
+techniques. A finite but small value of $\tilde g_{12}$ is required, with a
+concomitant lattice distortion compatible with experiments, and a
+tetragonal-monoclinic transition strongly first order. Remarkably, the
+bicollinear state found here displays a planar resistivity with the ""reversed""
+puzzling anisotropy discovered in transport experiments.Orthorhombic
+distortions are also incorporated and phase diagrams interpolating between
+pnictides and chalcogenides are presented. We conclude that the spin-lattice
+coupling discussed here is sufficient to explain the challenging properties of
+FeTe.",1606.00904v1
+2016-06-03,The effect of anisotropy on the absorption spectrum and the density of states of two-dimensional Frenkel exciton systems with Gaussian diagonal disorder,"On the optical absorption and the density of states of Frenkel exciton
+systems on square, rectangular, and triangular lattices with nearest-neighbor
+interactions and a Gaussian distribution of transition frequencies. The
+analysis is based on an elliptic integral approach that gives results over the
+entire spectrum. It is found that the absorption is weakly affected by the
+anisotropy in contrast to the density of states where the effects can be much
+stronger. The results for the square lattice are in good agreement with the
+finite array calculations of Schreiber and Toyozawa. Our findings suggest that
+the coherent potential approximation can be useful in interpreting the optical
+properties of two-dimensional systems with dominant nearest-neighbor
+interactions and Gaussian diagonal disorder where the optically excited states
+are Frenkel excitons.",1606.01130v1
+2016-06-03,Experimental demonstration of acoustic wave induced magnetization switching of dipole coupled magnetostrictive nanomagnets for ultralow power computing,"We report nanomagnetic switching with Acoustic Waves (AW) launched from
+interdigitated electrodes that modulate the stress anisotropy of elliptical
+cobalt nanoscale magnetostrictive magnets (340 nm x 270 nm x 12 nm) delineated
+on 128 degree Y-cut lithium niobate. The dipole-coupled nanomagnet pairs are in
+a single-domain state and are initially magnetized along the major axis of the
+ellipse, with their magnetizations parallel to each other. The magnetizations
+of nanomagnets having lower shape anisotropy are reversed upon acoustic wave
+propagation. Thereafter, the magnetization of these nanomagnets remains in the
+reversed state and demonstrate non-volatility. This executes a 'NOT' operation.
+This proof of acoustic wave induced magnetic state reversal in dipole-coupled
+nanomagnets implementing a 'NOT' gate operation could potentially lead to the
+development of extremely energy-efficient nanomagnetic logic. Furthermore,
+fabrication complexity is reduced immensely due to the absence of individual
+contacts to the nanomagnets, leading to lower energy dissipation",1606.01303v1
+2016-06-12,Probing primordial features with future galaxy surveys,"We study the capability of future measurements of the galaxy clustering power
+spectrum to probe departures from a power-law spectrum for primordial
+fluctuations. On considering the information from the galaxy clustering power
+spectrum up to quasi-linear scales, i.e. $k<0.1$ h Mpc$^{-1}$, we present
+forecasts for DESI, Euclid and SPHEREx in combination with CMB measurements. As
+examples of departures in the primordial power spectrum from a simple
+power-law, we consider four $Planck$ 2015 best-fits motivated by inflationary
+models with different breaking of the slow-roll approximation. These four
+representative models provide an improved fit to CMB temperature anisotropies,
+although not at statistical significant level. As for other extensions in the
+matter content of the simplest $\Lambda$CDM model, the complementarity of the
+information in the resulting matter power spectrum expected from these galaxy
+surveys and in the primordial power spectrum from CMB anisotropies can be
+effective in constraining cosmological models. We find that the three galaxy
+surveys can add significant information to CMB to better constrain the extra
+parameters of the four models considered.",1606.03747v3
+2016-06-20,Effective realization of random magnetic fields in compounds with large single-ion anisotropy,"We show that spin $S=1$ system with large and random single--ion anisotropy
+can be at low energies mapped to a $S=1/2$ system with random magnetic fields.
+This is for example realized in
+\mbox{Ni(Cl$_{1-x}$Br$_{x}$)$_2$-4SC(NH$_2$)$_2$} compound (DTNX) and therefore
+it represents a long sought realization of random local (on-site) magnetic
+fields in antiferromagnetic systems. We support the mapping by numerical study
+of $S=1$ and effective $S=1/2$ anisotropic Heisenberg chains and find excellent
+agreement for static quantities and also for the spin conductivity. Such
+systems can therefore be used to study the effects of local random magnetic
+fields on transport properties.",1606.06013v2
+2016-06-28,Zeeman splitting of conduction band in HgTe quantum wells near the Dirac point,"The Zeeman splitting of the conduction band in the HgTe quantum wells both
+with normal and inverted spectrum has been studied experimentally in a wide
+electron density range. The simultaneous analysis of the SdH oscillations in
+low magnetic fields at different tilt angles and of the shape of the
+oscillations in moderate magnetic fields gives a possibility to find the ratio
+of the Zeeman splitting to the orbital one and anisotropy of g-factor. It is
+shown that the ratios of the Zeeman splitting to the orbital one are close to
+each other for both types of structures, with a normal and inverted spectrum
+and they are close enough to the values calculated within kP method. In
+contrast, the values of g-factor anisotropy in the structures with normal and
+inverted spectra is strongly different and for both cases differs significantly
+from the calculated ones. We believe that such disagreement with calculations
+is a result of the interface inversion asymmetry in the HgTe quantum well,
+which is not taken into account in the kP calculations.",1606.08614v2
+2016-07-11,Heavy hole states in Germanium hut wires,"Hole spins have gained considerable interest in the past few years due to
+their potential for fast electrically controlled qubits. Here, we study holes
+confined in Ge hut wires, a so far unexplored type of nanostructure. Low
+temperature magnetotransport measurements reveal a large anisotropy between the
+in-plane and out-of-plane g-factors of up to 18. Numerical simulations verify
+that this large anisotropy originates from a confined wave function which is of
+heavy hole character. A light hole admixture of less than 1% is estimated for
+the states of lowest energy, leading to a surprisingly large reduction of the
+out-of-plane g-factors. However, this tiny light hole contribution does not
+influence the spin lifetimes, which are expected to be very long, even in non
+isotopically purified samples.",1607.02977v1
+2016-07-19,Magnetic anisotropy in the Kitaev model systems Na2IrO3 and RuCl3,"We study the ordered moment direction in the extended Kitaev-Heisenberg model
+relevant to honeycomb lattice magnets with strong spin-orbit coupling. We
+utilize numerical diagonalization and analyze the exact cluster groundstates
+using a particular set of spin coherent states, obtaining thereby quantum
+corrections to the magnetic anisotropy beyond conventional perturbative
+methods. It is found that the quantum fluctuations strongly modify the moment
+direction obtained at a classical level, and are thus crucial for a precise
+quantification of the interactions. The results show that the moment direction
+is a sensitive probe of the model parameters in real materials. Focusing on the
+experimentally relevant zigzag phases of the model, we analyze the currently
+available neutron and resonant x-ray diffraction data on Na2IrO3 and RuCl3, and
+discuss the parameter regimes plausible in these Kitaev-Heisenberg model
+systems.",1607.05676v2
+2016-08-12,NMR study of nematic spin fluctuations in a detwinned single crystal of underdoped Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$,"We report the experimental details of how mechanical detwinning can be
+implemented in tandem with high sensitivity nuclear magnetic resonance
+measurements and use this setup to measure the in-plane anisotropy of the
+spin-lattice relaxation rate in underdoped Ba(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$
+with $x=0.048$. The anisotropy reaches a maximum of 30\% at $T_{N}$, and the
+recovery data reveal that the glassy behavior of the spin fluctuations present
+in the twinned state persist in the fully detwinned crystal. A theoretical
+model is presented to describe the spin-lattice relaxation rate in terms of
+anisotropic nematic spin fluctuations.",1608.03899v1
+2016-08-15,Anisotropic Hanle lineshape via anisotropic magnetothermoelectric phenomena,"We observe anisotropic Hanle lineshape with unequal in-plane and out-of-plane
+non-local signals for spin precession measurements carried out on lateral
+metallic spin valves with transparent interfaces. The conventional
+interpretation for this anisotropy corresponds to unequal spin relaxation times
+for in-plane and out-of-plane spin orientations as for the case of 2D materials
+like graphene, but it is unexpected in a polycrystalline metallic channel.
+Systematic measurements as a function of temperature and channel length,
+combined with both analytical and numerical thermoelectric transport models,
+demonstrate that the anisotropy in the Hanle lineshape is magneto-thermal in
+origin, caused by the anisotropic modulation of the Peltier and Seebeck
+coefficients of the ferromagnetic electrodes. Our results call for the
+consideration of such magnetothermoelectric effects in the study of anisotropic
+spin relaxation.",1608.04420v2
+2016-08-16,Exchange anisotropy as mechanism for spin-stripe formation in frustrated spin chains,"We investigate the spin-stripe mechanism responsible for the peculiar
+nanometer modulation of the incommensurate magnetic order that emerges between
+the vector-chiral and the spin-density-wave phase in the frustrated zigzag
+spin-1/2 chain compound $\beta$-TeVO$_4$. A combination of magnetic-torque,
+neutron-diffraction and spherical-neutron-polarimetry measurements is employed
+to determine the complex magnetic structures of all three ordered phases. Based
+on these results, we develop a simple phenomenological model, which exposes the
+exchange anisotropy as the key ingredient for the spin-stripe formation in
+frustrated spin systems.",1608.04495v2
+2016-08-16,High anisotropy of fully hydrogenated borophene,"We have studied the mechanical properties and phonon dispersions of fully
+hydrogenated borophene (borophane) under strains by first principles
+calculations. Uniaxial tensile strains along the a- and b-direction,
+respectively, and biaxial tensile strain have been considered. Our results show
+that the mechanical properties and phonon stability of borophane are both
+highly anisotropic. The ultimate tensile strain along the a-direction is only
+0.12, but it can be as large as 0.30 along the b-direction. Compared to
+borophene and other 2D materials (graphene, graphane, silicene, silicane, h-BN,
+phosphorene and MoS2), borophane presents the most remarkable anisotropy in
+in-plane ultimate strain, which is very important for strain engineering.
+Furthermore, the phonon dispersions under the three applied strains indicate
+that borophane can withstand up to 5% and 15% uniaxial tensile strain along the
+a- and b-direction, respectively, and 9% biaxial tensile strain, indicating
+that mechanical failure in borophane is likely to originate from phonon
+instability.",1608.04788v2
+2016-08-19,Quantized conductance and large g-factor anisotropy in InSb quantum point contacts,"Due to a strong spin-orbit interaction and a large Land\'e g-factor, InSb
+plays an important role in research on Majorana fermions. To further explore
+novel properties of Majorana fermions, hybrid devices based on quantum wells
+are conceived as an alternative approach to nanowires. In this work, we report
+a pronounced conductance quantization of quantum point contact devices in
+InSb/InAlSb quantum wells. Using a rotating magnetic field, we observe a large
+in-plane (|g1|=26) and out-of-plane (|g1|=52) g-factor anisotropy.
+Additionally, we investigate crossings of subbands with opposite spins and
+extract the electron effective mass from magnetic depopulation of
+one-dimensional subbands.",1608.05478v1
+2016-08-19,Progressive magnetic softening of ferromagnetic layers in multilayer ferromagnet-nonmagnet systems and the role of granularity,"We report a study of the structural and magnetic behavior of the topmost
+magnetic layer in a ferromagnet-nonmagnet (Co-Au) multilayer system. Glancing
+angle X-ray diffraction measurements performed on a series of multilayers
+showed a gradually increasing degree of amorphization of the topmost magnetic
+layer with increasing number of bilayers. Concurrently, the magnetic hardness
+and magneto-crystalline anisotropy of the top Co layer were found to decrease,
+as observed by magneto-optical Kerr effect measurements. This magnetic
+softening has been discussed in the light of Herzer's random anisotropy model.
+Micromagnetic simulations of the multilayer system also corroborated these
+observations.",1608.05568v5
+2016-08-23,Anisotropy-Induced Quantum Interference and Population Trapping Between Orthogonal Quantum Dot Exciton States in Semiconductor Cavity Systems,"We describe how quantum dot semiconductor cavity systems can be engineered to
+realize anisotropy-induced dipole-dipole coupling between orthogonal dipole
+states in a single quantum dot. Quantum dots in single-mode cavity structures
+as well as photonic crystal waveguides coupled to spin states or linearly
+polarized excitons are considered. We demonstrate pronounced dipole-dipole
+coupling to control the radiative decay rate of excitons and form pure
+entangled states in the long time limit. We investigate both field-free
+entanglement evolution and coherently pumped exciton regimes, and show how a
+double pumping scenario can completely eliminate the decay of coherent Rabi
+oscillations and lead to population trapping. In the Mollow regime, we explore
+the emitted spectra from the driven dipoles and show how a non-pumped dipole
+can take on the form of a spectral triplet, quintuplet, or a singlet, which has
+applications for producing subnatural linewidth single photons and more easily
+accessing regimes of high-field quantum optics and cavity-QED.",1608.06650v3
+2016-08-15,An approach to directly probe simultaneity,"The theory of special relativity derives from the Lorentz transformation. The
+Lorentz transformation implies differential simultaneity and light speed
+isotropy. Experiments to probe differential simultaneity should be able to
+distinguish the Lorentz transformation from a kinematically-similar alternate
+transformation that predicts absolute simultaneity, the absolute Lorentz
+transformation. Here, we describe how published optical tests of light speed
+isotropy/anisotropy cannot distinguish between the two transformations. We show
+that the shared equations of the two transformations, from the perspective of
+the ""stationary"" observer, are sufficient to predict null results in optical
+resonator experiments and in tests of frequency changes in one-way light paths.
+In an influential 1910 exposition on differential simultaneity, Comstock
+described how a ""stationary"" observer would observe different clock readings
+for spatially-separated ""moving"" clocks. The difference in clock readings is an
+integral aspect of differential simultaneity. We derive the equation for the
+difference in clock readings and show that it is equivalent to the Sagnac
+correction that describes light speed anisotropies in satellite communications.
+We describe an experimental strategy that can measure the differences in
+spatially-separated clock times to allow a direct probe of the nature of
+simultaneity.",1608.08516v1
+2016-08-31,Tidal disruption rates in non-spherical galactic nuclei formed by galaxy mergers,"We explore the rates of tidal disruption events (TDEs) of stars by
+supermassive black holes (SBHs) in galactic nuclei formed in mergers followed
+by a formation and coalescence of a binary SBH. Such systems initially have a
+deficit of stars on low-angular-momentum orbits caused by the slingshot process
+during the binary SBH stage, which tends to reduce the flux of stars into the
+SBH compared to the steady-state value. On the other hand, a newly formed
+galactic nucleus has a non-spherical shape which enhances the mixing of stars
+in angular momentum and thus the TDE rate. In galaxies with relatively low SBH
+masses (<10^7 Msun), relaxation times are short enough to wash out the
+anisotropy in initial conditions, and for more massive SBH the enhancement of
+flux due to non-sphericity turns out to be more important than its suppression
+due to initial anisotropy. Therefore, the present-day TDE rates generally
+exceed conventional steady-state estimates based on a spherical isotropic
+approximation. We thus conjecture that the lower observationally inferred TDE
+rates compared to theoretical predictions cannot be attributed to the depletion
+of low-angular-momentum stars by SBH binaries.",1609.00009v1
+2016-09-07,Anisotropic dependence of tune-out wavelength near Dy 741-nm transition,"We report the first measurement of a tune-out wavelength for ground-state
+bosonic Dy and linearly polarized light. The tune-out wavelength measured is
+near the narrow-line 741-nm transition in $^{162}$Dy, and is the wavelength at
+which the total Stark shift of the ground state vanishes. We find that it
+strongly depends on the relative angle between the optical field and
+quantization axis due to Dy's large tensor polarizability. This anisotropy
+provides a wide, 22-GHz tunability of the tune-out frequency for linearly
+polarized light, in contrast to Rb and Cs whose near-infrared tune-out
+wavelengths do not exhibit large anisotropy. The measurements of the total
+light shift are performed by measuring the contrast of multipulse Kapitza-Dirac
+diffraction. The calculated wavelengths are within a few GHz of the measured
+values using known Dy electronic transition data. The lack of hyperfine
+structure in bosonic Dy implies that the tune-out wavelengths for the other
+bosonic Dy isotopes should be related to this $^{162}$Dy measurement by the
+known isotope shifts.",1609.02111v1
+2016-09-12,Currentless reversal of Néel vector in antiferromagnets,"The bias driven perpendicular magnetic anisotropy is a magneto-electric
+effect that can realize 90$^\circ$ magnetization rotation and even 180$% ^\circ
+$ flip along the easy axis in the ferromagnets with a minimal energy
+consumption. This study theoretically demonstrates a similar phenomenon of the
+N\'{e}el vector reversal via a short electrical pulse that can mediate
+perpendicular magnetic anisotropy in the antiferromagnets. The analysis based
+on the dynamical equations as well as the micro-magnetic simulations reveals
+the important role of the inertial behavior in the antiferromagnets that
+facilitates the N\'{e}el vector to overcome the barrier between two free-energy
+minima of the bistable states along the easy axis. In contrast to the
+ferromagnets, this N\'{e}el vector reversal does not accompany angular moment
+transfer to the environment, leading to acceleration in the dynamical response
+by a few orders of magnitude. Further, a small switching energy requirement of
+a few attojoules illustrates an added advantage of the phenomenon in low-power
+spintronic applications.",1609.03454v2
+2016-09-13,Spin-flop transition accompanied with changing the type of magnetic ordering,"We discuss theoretically rather rear example of spin-flop transition which is
+accompanied with changing the type of magnetic ordering and which seemingly has
+not been addressed yet. We demonstrate that changing the type of magnetic
+ordering can manifest itself in antiferromagnetic (AF) resonance experiments as
+an apparent peculiar switching of the anisotropy at the transition from the
+easy-axis type to the easy-plane one. We argue that this kind of spin-flop
+transition is observed recently by K.Yu. Povarov et al., Phys. Rev. B 87,
+214402 (2013) in Cu(pz)$_2$(ClO$_4$)$_2$ (where pz denotes pyrazine), one of
+the best realizations of spin-1/2 Heisenberg AFs on square lattice having a
+very small anisotropy. We show that the magnetic ordering changes at the
+spin-flop transition in this material in the direction perpendicular to AF
+square planes. We examine the microscopic mechanism of such behavior in
+Cu(pz)$_2$(ClO$_4$)$_2$ and find that dipolar forces and extremely small
+exchange coupling between spins from neighboring planes are responsible for it.",1609.03702v2
+2016-09-16,High-pressure study of the basal-plane anisotropy of the upper critical field of the topological superconductor SrxBi2Se3,"We report a high-pressure transport study of the upper-critical field,
+$B_{c2}(T)$, of the topological superconductor Sr$_{0.15}$Bi$_2$Se$_3$ ($T_c =
+3.0$ K). $B_{c2}(T)$ was measured for magnetic fields directed along two
+orthogonal directions, $a$ and $a^*$, in the trigonal basal plane. While
+superconductivity is rapidly suppressed at the critical pressure $p_c \sim 3.5$
+GPa, the pronounced two-fold basal-plane anisotropy $B_{c2}^a/B_{c2}^{a^*} =
+3.2$ at $T=0.3$ K, recently reported at ambient pressure (Pan et al., 2016), is
+reinforced and attains a value of $\sim 5$ at the highest pressure (2.2 GPa).
+The data reveal that the unconventional superconducting state with broken
+rotational symmetry is robust under pressure.",1609.04945v1
+2016-09-20,Anomalous Hall hysteresis in Tm3Fe5O12/Pt with strain-induced perpendicular magnetic anisotropy,"We demonstrate robust interface strain-induced perpendicular magnetic
+anisotropy in atomically flat ferrimagnetic insulator Tm3Fe5O12 films grown
+with pulsed laser deposition on substituted-Gd3Ga5O12 substrate which maximizes
+the tensile strain at the interface. In bilayers consisting of Pt and TIG, we
+observe large squared Hall hysteresis loops over a wide range of thicknesses of
+Pt at room temperature. When a thin Cu layer is inserted between Pt and TIG,
+the Hall hysteresis magnitude decays but stays finite as the thickness of Cu
+increases up to 5 nm. However, if the Cu layer is placed atop Pt instead, the
+Hall hysteresis magnitude is consistently larger than when the Cu layer with
+the same thickness is inserted in between for all Cu thicknesses. These results
+suggest that both the proximity-induced ferromagnetism and spin current
+contribute to the anomalous Hall effect.",1609.06367v1
+2016-09-27,First-principles studies of the Optical anisotropy of R3 space group chalcogenides crystal AX2MQ6,"In order to explain the reason that all the sythesised \ce{AX2MQ6}
+chalcogenides compounds are phase-matching while isomorphic chalcogenides
+compounds \ce{AX4M5Q12} are not phase-matched materials. The linear optical
+property birefringence and non-linear optical property of $R3$ space group
+crystals \ce{AX2MQ6} have been calculated to compare with \ce{AX4M5Q12}. Their
+Electron Localization Function(ELF) was calculated to show that the acentricity
+of the bonds on $sp^3$ hybridization \ce{Q^2-} ions is the main origin of
+optical anisotropy. To quantificat the acentricity, a geometric parameter
+dihedral angle between tetrahedral undersides and xy-planes was defined. We
+find theoretically the birefringence depend on the defined geometric parameter
+and ion radius. This relation between birefringence and structure resonalbly
+explain the abnormal difference of birefringence of isostructural \ce{AX2MQ6}
+and \ce{AX4M5Q12} and useful for exploring new phase-matching IR-NLO crystals.",1609.08243v3
+2016-09-27,Inverted anisotropy in the in-plane dissipation of BSCCO tapes: preliminary results,"The electrical properties of superconducting tapes and coatings in the
+direction transverse to the long dimension of the composite has been rarely
+studied. However, transverse dissipation can eventually determine the behavior
+of a transmission line in the case of failure due to the presence of
+transversal cracks, and is also fundamental in the AC regime. In this paper we
+present a preliminary experimental study of the electrical transport properties
+along the transverse direction of BSCCO-metal tapes, and compare them with
+those measured along the long axis of the material. In spite of the fact that
+the tapes under study are not multi-filamentary, our experiments suggest that
+there is a measurable anisotropy of the transport properties between the
+longitudinal and transverse directions.",1609.08662v1
+2016-09-30,Simultaneous control of the Dzyaloshinskii-Moriya interaction and magnetic anisotropy in nanomagnetic trilayers,"Magneto-optical Kerr effect (MOKE) microscopy measurements of magnetic bubble
+domains demonstrate that Ar+ irradiation around 100 eV can tune the
+Dzyaloshinskii-Moriya interaction (DMI) in Pt/Co/Pt trilayers. Varying the
+irradiation energy and dose changes the DMI sign and magnitude separately from
+the magnetic anisotropy, allowing tuning of the DMI while holding the coercive
+field constant. This simultaneous control emphasizes the different physical
+origins of these effects. To accurately measure the DMI, we propose and apply a
+physical model for a poorly understood peak in domain wall velocity at zero
+in-plane field. The ability to tune the DMI with the spatial resolution of the
+Ar+ irradiation enables new fundamental investigations and technological
+applications of chiral nanomagnetics.",1609.09790v2
+2016-10-01,Pumping electrons in graphene to the $\mathbf{M}$-point in the Brillouin zone: The emergence of anisotropic plasmons,"We consider the existence of plasmons in a non-equilibrium situation where
+electrons from the valence band of graphene are pumped to states in the
+Brillouin zone around the $\mathbf{M}$-point by a high intensity UV
+electromagnetic field. The resulting out-of-equilibrium electron gas is later
+probed by a weak electromagnetic field of different frequency. We show that the
+optical properties of the system and the dispersion of the plasmons are
+strongly anisotropic, depending on the pumping radiation properties: its
+intensity, polarization, and frequency. This anisotropy has its roots in the
+saddle-like nature of the electronic dispersion relation around that particular
+point in the Brillouin zone.
+  It is found that despite the strong anisotropy, the dispersion of the
+plasmons scales with the square root of the wave number but is characterized an
+effective Fermi energy, which depends on the properties of the pumping
+radiation. Our calculations go beyond the usual Dirac cone approximation taking
+the full band structure of graphene into account. This is a necessary condition
+for discussing plasmons at the $\mathbf{M}$-point in the Brillouin zone.",1610.00162v1
+2016-10-03,The first moment of azimuthal anisotropy in nuclear collisions from AGS to LHC energies,"We review topics related to the first moment of azimuthal anisotropy ($v_1$),
+commonly known as directed flow, focusing on both charged particles and
+identified particles from heavy-ion collisions. Beam energies from the highest
+available, at the CERN LHC, down to projectile kinetic energies per nucleon of
+a few GeV per nucleon, as studied in experiments at the Brookhaven AGS, fall
+within our scope. We focus on experimental measurements and on theoretical work
+where direct comparisons with experiment have been emphasized. The physics
+addressed or potentially addressed by this review topic includes the study of
+Quark Gluon Plasma, and more generally, investigation of the Quantum
+Chromodynamics phase diagram and the equation of state describing the
+accessible phases.",1610.00646v1
+2016-10-06,Flat bands and Dirac cones in breathing lattices,"In breathing pyrochlores and kagomes, couplings between neighbouring
+tetrahedra and triangles are free to differ. Breathing lattices thus offer the
+possibility to explore a different facet of the rich physics of these systems.
+Here we consider nearest-neighbour classical Heisenberg interactions, both
+ferromagnetic and antiferromagnetic, and study how the anisotropy of breathing
+lattices modifies the mode spectrum of pyrochlore and kagome systems. The
+nature and degeneracy of the flat bands are shown to be preserved for any value
+of the anisotropy. These flat bands can coexist with Dirac nodes at the
+$\Gamma$ point when the model becomes particle-hole symmetric. We also derive
+the nature of the ground state for the breathing kagome lattice, which bears a
+spontaneous chirality when neighbouring triangles are alternatively
+ferromagnetic and antiferromagnetic.",1610.01748v1
+2016-10-06,Spin-torque switching and control using chirped oscillating currents,"We propose to use oscillating spin currents with slowly varying frequency
+(chirp) to manipulate and control the magnetization dynamics in a nanomagnet.
+By recasting the Landau-Lifshitz-Slonczewski equation in a quantum-like
+two-level formalism, we show that a chirped spin current polarized in the
+direction normal to the anisotropy axis can induce a stable precession of the
+magnetic moment at any angle (up to $90^\circ$) with respect to the anisotropy
+axis. The drive current can be modest ($10^6\,\rm A/cm^2$ or lower) provided
+the chirp rate is sufficiently slow. The induced precession is stable against
+thermal noise, even for small nano-objects at room temperature. Complete
+reversal of the magnetization can be achieved by adding a small external
+magnetic field antiparallel to the easy axis. Alternatively, a combination of
+chirped ac and dc currents with different polarization directions can also be
+used to trigger the reversal.",1610.01819v2
+2016-10-10,Interdiffusion in epitaxial ultrathin Co2FeAl/MgO heterostructures with interface-induced perpendicular magnetic anisotropy,"The structures of epitaxial ultrathin Co2FeAl/MgO(001) heterostructures
+relating to the interface-induced perpendicular magnetic anisotropy (PMA) were
+investigated using scanning transmission electron microscopy, energy dispersive
+x-ray spectroscopy, and x-ray magnetic circular dichroism. We found that Al
+atoms from the Co2FeAl layer significantly interdiffuse into MgO, forming an
+Al-deficient Co-Fe-Al/Mg-Al-O structure near the Co2FeAl/MgO interface. This
+atomic replacement may play an additional role for enhancing PMA, which is
+consistent with the observed large perpendicular orbital magnetic moments of Fe
+atoms at the interface. This work suggests that control of interdiffusion at
+ferromanget/barrier interfaces is critical for designing an interface-induced
+PMA system.",1610.03015v1
+2016-10-10,Constraining quantum collapse inflationary models with CMB data,"The hypothesis of the self-induced collapse of the inflaton wave function was
+proposed as responsible for the emergence of inhomogeneity and anisotropy at
+all scales. This proposal was studied within an almost de Sitter space-time
+approximation for the background, which led to a perfect scale-invariant power
+spectrum, and also for a quasi-de Sitter background, which allows to
+distinguish departures from the standard approach due to the inclusion of the
+collapse hypothesis. In this work we perform a Bayesian model comparison for
+two different choices of the self-induced collapse in a full quasi-de Sitter
+expansion scenario. In particular, we analyze the possibility of detecting the
+imprint of these collapse schemes at low multipoles of the anisotropy
+temperature power spectrum of the Cosmic Microwave Background (CMB) using the
+most recent data provided by the Planck Collaboration. Our results show that
+one of the two collapse schemes analyzed provides the same Bayesian evidence of
+the minimal standard cosmological model $\Lambda$CDM, while the other scenario
+is weakly disfavoured with respect to the standard cosmology.",1610.03091v2
+2016-10-10,TeV Cosmic-Ray Anisotropy from the Magnetic Field at the Heliospheric Boundary,"We performed numerical calculations to test the suggestion by Desiati &
+Lazarian (2013) that the anisotropies of TeV cosmic rays may arise from their
+interactions with the heliosphere. For this purpose, we used a magnetic field
+model of the heliosphere and performed direct numerical calculations of
+particle trajectories. Unlike earlier papers testing the idea, we did not
+employ time-reversible techniques that are based on Liouville's theorem. We
+showed numerically that for scattering by the heliosphere the conditions of
+Liouville's theorem are not satisfied and the adiabatic approximation and
+time-reversibility of the particle trajectories are not valid. Our results
+indicate sensitivity to the magnetic structure of the heliospheric magnetic
+field, and we expect that this will be useful for probing this structure in
+future research.",1610.03097v1
+2016-10-11,Strong anisotropy within a Heisenberg model in the J=1/2 insulating state of Sr2Ir0.8Ru0.2O4,"The dispersive magnetic excitations in Sr2IrO4 have previously been well
+described within an isospin-1/2 Heisenberg model on a square lattice that
+revealed parallels with La2CuO4. Here we investigate the inelastic spectra of
+Sr2Ir0.8Ru0.2O4 with resonant inelastic x-ray scattering (RIXS) at the Ir
+L3-edge. The results are well described using linear spin-wave theory within a
+similar Heisenberg model applicable to Sr2IrO4, however the disorder induced by
+the substitution of 20% Ir4+ ions for Ru4+ removes longer range exchange
+interactions. A large spin-gap (40 meV) is measured indicating strong
+anisotropy from spin-orbit coupling that is manifest due to the altered
+magnetic structure in Sr2Ir0.8Ru0.2O4 with c-axis aligned moments compared to
+the basal plane moments in the parent. Collectively the results indicate the
+robustness of a Heisenberg model description even when the magnetic structure
+is altered and the J=1/2 moments diluted.",1610.03399v1
+2016-10-12,Thermal Anisotropy Enhanced by Phonon Size Effects in Nanoporous Materials,"While thermal anisotropicity is a desirable materials property for many
+applications, including transverse thermoelectrics and thermal management in
+electronic devices, it remains elusive in practical natural compounds. In this
+work, we show how nanoporous materials with anisotropic pore lattices can be
+used as a platform for inducing strong heat transport directionality in
+isotropic materials. Using density functional theory and the phonon Boltzmann
+transport equation, we calculate the phonon-size effects and thermal
+conductivity of nanoporous silicon with different anisotropicpore lattices. Our
+calculations predict a strong directionality in the thermal conductivity,
+dictated by the difference in the pore-pore distances along the two Cartesian
+axes. As the space between pores along the direction of the applied temperature
+gradient represents the phonon bottleneck, an anisotropic pores lattice
+distortion induces directionality in heat transport. Using Fourier's law, we
+also compute diffusive heat transport for the same geometries obtaining
+significantly smaller anisotropicity, revealing the crucial role of phonon-size
+effects in tuning thermal transport directionality. Besides enhancing our
+understanding of nanoscale heat transport, our results demonstrate the promise
+of nanoporous materials for modulating anisotropy in thermal conductivity.",1610.03760v2
+2016-10-17,Controlling energy transfer time between two coupled magnetic vortex-state disks,"The influence of the in-plane uniaxial anisotropy (IPUA) in the mutual energy
+transfer time ($\tau$) between two identical coupled nanodisks was studied.
+Using an analytical dipolar model we obtained the interactions between the
+disks along x and y directions (the coupling integrals) as a function of the
+uniaxial anisotropy constant (K$_{\sigma}$) and the distance. We find that the
+IPUA increases the interaction between the disks allowing shorter energy
+transfer times. For our range of K$_{\sigma}$ values we get a drop in the
+values of $\tau$ of up to about 70$\%$. From the lagrangian of the system we
+obtained the equations of motion and the coupling frequencies of the dynamic
+system as a function of distance and K$_{\sigma}$. The coupling frequencies
+were also obtained from micromagnetic simulations. Our results of the
+simulations are in agreement with the analytical results.",1610.05109v1
+2016-10-22,Giant nonreciprocal emission of spin waves in Ta/Py bilayers,"Spin waves are propagating disturbances in the magnetization of magnetic
+materials. One of their interesting properties is the nonreciprocity,
+exhibiting that their amplitude depends on the magnetization direction.
+Nonreciprocity in spin waves is of great interest in both fundamental science
+and applications, as it offers an extra knob to control the flow of waves for
+the technological fields of logics and switch applications. We show a high
+nonreciprocity in spin waves from Ta/Py bilayer systems with out-of-plane
+magnetic fields. The nonreciprocity depends on the thickness of Ta underlayer
+which is found to induce an interfacial anisotropy. The origin of observed high
+nonreciprocity is twofold; different polarities of the in-plane magnetization
+due to different angles of canted out-of-plane anisotropy and the spin pumping
+effect at the Ta/Py interface. Our findings provide an opportunity to engineer
+highly efficient nonreciprocal spin wave based applications such as
+nonreciprocal microwave devices, magnonic logic gates, and information
+transports.",1610.07023v1
+2016-10-25,Anisotropy and memory during cage breaking events close to a wall,"The slow dynamics in a glassy hard-sphere system is dominated by cage
+breaking events, i.e., rearrangements where a particle escapes from the cage
+formed by its neighboring particles. We study such events for an overdamped
+colloidal system by the means of Brownian dynamics simulations. While it is
+difficult to relate cage breaking events to structural mean field results in
+bulk, we show that the microscopic dynamics of particles close to a wall can be
+related to the anisotropic two-particle density. In particular, we study
+cage-breaking trajectories, mean forces on a tracked particle, and the impact
+of the history of trajectories. Based on our simulation results, we further
+construct two different one-particle random-walk models - one without and one
+with memory incorporated - and find the local anisotropy and the
+history-dependence of particles as crucial ingredients to describe the escape
+from a cage. Finally, our detailed study of a rearrangement event close to a
+wall not only reveals the memory effect of cages, but leads to a deeper insight
+into the fundamental mechanisms of glassy dynamics.",1610.07846v1
+2016-10-28,Anisotropic invariance and the distribution of quantum correlations,"We report the discovery of two new invariants for three-qubit states which,
+similarly to the 3-tangle, are invariant under local unitary transformations
+and permutations of the parties. These quantities have a direct interpretation
+in terms of the anisotropy of pairwise spin correlations. Applications include
+a universal ordering of pairwise quantum correlation measures for pure
+three-qubit states; tradeoff relations for anisotropy, 3-tangle and Bell
+nonlocality; strong monogamy relations for Bell inequalities,
+Einstein-Podolsky-Rosen steering inequalities, geometric discord and fidelity
+of remote state preparation (including results for arbitrary three-party
+states); and a statistical and reference-frame-independent form of quantum
+secret sharing.",1610.09302v3
+2016-10-28,Uniform convergent scheme for strongly anisotropic diffusion equations with closed field lines,"In magnetized plasma, the magnetic field confines particles around field
+lines. The ratio between the intensity of the parallel and perpendicular
+viscosity or heat conduction may reach the order of $10^{12}$. When the
+magnetic fields have closed field lines and form a ""magnetic island"", the
+convergence order of most known schemes depends on the anisotropy strength. In
+this paper, by integration of the original differential equation along each
+closed field line, we introduce a simple but very efficient asymptotic
+preserving reformulation, which yields uniform convergence with respect to the
+anisotropy strength. Only slight modification to the original code is required
+and neither change of coordinates nor mesh adaptation is needed. Numerical
+examples demonstrating the performance of the new scheme are presented.",1610.09370v1
+2016-10-31,Amplicification of Voltage Controlled Magnetic Anisotropy Effect with Negative Capacitance,"The high current density required by Magnetic Tunneling Junction (MTJ)
+switching driven by Spin Transfer Torque (STT) effect leads to large power
+consumption and severe reliability issues therefore hinder the timetable for
+STT Magnetic Random Access Memory (STT-MRAM) to mass market. By utilizing
+Voltage Controlled Magnetic Anisotropy (VCMA) effect, the MTJ can be switched
+by voltage effect and is postulated to achieve ultra-low power (fJ). However,
+the VCMA coefficient measured in experiments is far too small for MTJ dimension
+below 100 nm. Here in this work, a novel approach for the amplification of VCMA
+effect which borrow ideas from negative capacitance is proposed. The
+feasibility of the proposal is proved by physical simulation and in-depth
+analysis.",1610.09831v1
+2016-10-31,Phenomenological predictions of 3+1d anisotropic hydrodynamics,"We make phenomenological predictions for particle spectra and elliptic flow
+in heavy-ion collisions using 3+1d anisotropic hydrodynamics (aHydro) including
+the effects of both shear and bulk viscosities. The dynamical equations
+necessary are derived by taking moments of the Boltzmann equation allowing for
+three distinct (diagonal) momentum-space anisotropy parameters. The formulation
+is based on relaxation-time approximation for the collisional kernel and a
+lattice-QCD-based equation of state. Evolving the system to late times, we
+calculate particle production using THERMINATOR 2, modified to account for an
+ellipsoidal distribution function. We obtain particle spectra for different
+particle species such as pions, kaons, and protons, and elliptic flow $v_2$ as
+a function of centrality, transverse momentum, and rapidity. In our model, we
+have four free parameters, i.e. freeze-out temperature, initial central energy
+density, initial momentum-space anisotropies, and shear viscosity to entropy
+density ratio. Using a multidimensional fit to LHC experimental data, we make a
+preliminary extraction of these parameters. We find reasonable agreement
+between 3+1d aHydro and available experimental data for $\eta/s\sim 0.23$.",1610.10055v1
+2016-11-02,Surface effects on ferromagnetic resonance in magnetic nanocubes,"We study the effect of surface anisotropy on the spectrum of spin-wave
+excitations in a magnetic nanocluster and compute the corresponding absorbed
+power. For this, we develop a general numerical method based on the (undamped)
+Landau-Lifshitz equation, either linearized around the equilibrium state
+leading to an eigenvalue problem or solved using a symplectic technique. For
+box-shaped clusters, the numerical results are favorably compared to those of
+the finite-size linear spin-wave theory. Our numerical method allows us to
+disentangle the contributions of the core and surface spins to the spectral
+weight and absorbed power. In regard to the recent developments in synthesis
+and characterization of assemblies of well defined nano-elements, we study the
+effects of free boundaries and surface anisotropy on the spin-wave spectrum in
+iron nanocubes and give orders of magnitude of the expected spin-wave
+resonances. For an 8 nm iron nanocube, we show that the absorbed power spectrum
+should exhibit a low-energy peak around 10 GHz, typical of the uniform mode,
+followed by other low-energy features that couple to the uniform mode but with
+a stronger contribution from the surface. There are also high-frequency
+exchange-mode peaks around 60 GHz.",1611.00614v1
+2016-07-17,Effect of stress induced anisotropy and applied magnetic field on second order perturbed energy of thin ferromagnetic films,"All the simulations were carried out for sc(001) film with three (N=3)
+layers. The effect of applied magnetic field and stress induced anisotropy on
+energy of ultra-thin ferromagnetic films has been investigated using Heisenberg
+Hamiltonian with second order perturbation. The energy becomes minimums at
+certain values of angles, applied magnetic field and stress, by indicating that
+film can be easily oriented in theses certain directions by applying particular
+applied magnetic field or stress. For example, when applied magnetic field
+perpendicular to film plane is 3.6, the film can be easily oriented along 0.97
+and 2.65 radians directions. When in plane applied magnetic field is 3, energy
+minimums can be detected at 1 and 2.6 radians. When applied stress is 2.7, film
+can be easily oriented in 2.8 direction.",1611.02229v1
+2016-11-08,Directional Anisotropy of Crack Propagation Along $Σ$3 Grain Boundary in BCC Fe,"Crack growth behaviour along the coherent twin boundary (CTB), i.e.,
+$\Sigma$3{112} of BCC Fe is investigated using molecular dynamics (MD)
+simulations. The growth of an atomistically sharp crack with {112}$<$110$>$
+orientation has been examined along the two opposite $<$111$>$ directions of
+CTB under mode-I loading at a constant strain rate. Separate MD simulations
+were carried out with crack inserted in the left side, right side and middle of
+the specimen model system. The results indicate that the crack grows
+differently along the two opposite $<$111$>$ directions. In case of a crack
+inserted in the left side, the crack grows in ductile manner, while it
+propagates in semi-brittle manner in the case of crack inserted in the right
+side. The directional dependence of crack growth along the CTB is also
+confirmed by the stress-strain behaviour. This anisotropy in crack growth
+behaviour has been attributed to the twinning-antitwinning asymmetry of
+1/6$<$111$>$ partial dislocations on {112} planes.",1611.02458v1
+2016-11-10,Total variation denoising in $l^1$ anisotropy,"We aim at constructing solutions to the minimizing problem for the variant of
+Rudin-Osher-Fatemi denoising model with rectilinear anisotropy and to the
+gradient flow of its underlying anisotropic total variation functional. We
+consider a naturally defined class of functions piecewise constant on
+rectangles (PCR). This class forms a strictly dense subset of the space of
+functions of bounded variation with an anisotropic norm. The main result shows
+that if the given noisy image is a PCR function, then solutions to both
+considered problems also have this property. For PCR data the problem of
+finding the solution is reduced to a finite algorithm. We discuss some
+implications of this result, for instance we use it to prove that continuity is
+preserved by both considered problems.",1611.03261v2
+2016-11-10,Recent progress in astrophysical plasma turbulence from solar wind observations,"This paper summarises some of the recent progress that has been made in
+understanding astrophysical plasma turbulence in the solar wind, from in situ
+spacecraft observations. At large scales, where the turbulence is predominantly
+Alfvenic, measurements of critical balance, residual energy, and 3D structure
+are discussed, along with comparison to recent models of strong Alfvenic
+turbulence. At these scales, a few percent of the energy is also in compressive
+fluctuations, and their nature, anisotropy, and relation to the Alfvenic
+component is described. In the small scale kinetic range, below the ion
+gyroscale, the turbulence becomes predominantly kinetic Alfven in nature, and
+measurements of the spectra, anisotropy, and intermittency of this turbulence
+are discussed with respect to recent cascade models. One of the major remaining
+questions is how the turbulent energy is dissipated, and some recent work on
+this question, in addition to future space missions which will help to answer
+it, are briefly discussed.",1611.03386v1
+2016-11-14,A minimal empirical model for the cosmic far-infrared background anisotropies,"Cosmic far-infrared background (CFIRB) probes unresolved dusty star-forming
+galaxies across cosmic time and is complementary to ultraviolet and optical
+observations of galaxy evolution. In this work, we interpret the observed CFIRB
+anisotropies using an empirical model based on resolved galaxies in ultraviolet
+and optical surveys. Our model includes stellar mass functions, star-forming
+main sequence, and dust attenuation. We find that the commonly used linear
+Kennicutt relation between infrared luminosity and star formation rate
+overproduces the observed CFIRB amplitudes. The observed CFIRB requires that
+low-mass galaxies have lower infrared luminosities than expected from the
+Kennicutt relation, implying that low-mass galaxies have lower dust content and
+weaker dust attenuation. Our results demonstrate that CFIRB not only provides a
+stringent consistency check for galaxy evolution models but also constrains the
+dust content of low-mass galaxies.",1611.04517v2
+2016-11-17,Recent results on collective effects in small systems from PHENIX at RHIC,"Collisions of simple systems, such as $p$+$p$, or $p$+Nucleus have been used
+as benchmarks for our understanding of heavy ion collsions, since it was
+assumed they would be free of the effects from hot nuclear matter.
+  Recently long range correlations and anisotropies of momentum spectra have
+been seen in such collisions, challenging this assumption. Such phenomena have
+been understood to be the result of the collective motion, which can best be
+described by hydrodynamics, whose initial conditions are set by the geometry of
+the colliding systems, together with their fluctuations. This talk will discuss
+the recent results from the PHENIX experiment at RHIC using a variety of
+colliding species ($p$+Au, $d$+Au, $^{3}$He+Au) that give a better
+understanding of the origin of the observed correlations and anisotropies, thus
+providing insight as to whether a quark gluon plasma is formed in these simple
+systems.",1611.05752v1
+2016-11-17,On Escaping a Galaxy Cluster in an Accelerating Universe,"We derive the escape velocity profile for an Einasto density field in an
+accelerating universe and demonstrate its physical viability by comparing
+theoretical expectations to both light-cone data generated from N-body
+simulations and archival data on 20 galaxy clusters. We demonstrate that the
+projection function ($g(\beta )$) is deemed physically viable only for the
+theoretical expectation that includes a cosmology-dependent term. Using
+simulations, we show that the inferred velocity anisotropy is more than
+6{\sigma} away from the expected value for the theoretical profile that ignores
+the acceleration of the universe. In the archival data, we constrain the
+average velocity anisotropy parameter of a sample of 20 clusters to be $\beta
+={0.248}_{-0.360}^{+0.164}$ at the 68% confidence level. Lastly, we briefly
+discuss how our analytic model may be used as a novel cosmological probe based
+on galaxy clusters.",1611.05816v1
+2016-11-18,Density dependent exciton dynamics and L valley anisotropy in germanium,"Optical pump-THz probe spectroscopy is used to investigate the exciton
+formation dynamics and its intensity dependence in bulk Ge. Associated with the
+intra-excitonic 1s-2p transition, the gradual build-up of an absorption peak
+around 3.1 meV (0.75 THz) signifies the delayed exciton formation after optical
+pump which is accelerated for higher excitation densities. Analyzing the
+spectral shape of this THz absorption resonance, two distinct resonances are
+found which are attributed to the mass-anisotropy of L valley electrons via a
+microscopic theory.",1611.06117v1
+2016-11-28,A test of local Lorentz invariance with Compton scattering asymmetry,"We report on a measurement of the constancy and anisotropy of the speed of
+light relative to the electrons in photon-electron scattering. We used the
+Compton scattering asymmetry measured by the new Compton polarimeter in Hall~C
+at Jefferson Lab to test for deviations from unity of the vacuum refractive
+index ($n$). For photon energies in the range of 9 - 46 MeV, we obtain a new
+limit of $1-n < 1.4 \times 10^{-8}$. In addition, the absence of sidereal
+variation over the six month period of the measurement constrains any
+anisotropies in the speed of light. These constitute the first study of Lorentz
+invariance using Compton asymmetry. Within the minimal standard model extension
+framework, our result yield limits on the photon and electron coefficients
+$\tilde{\kappa}_{0^+}^{YZ}, c_{TX}, \tilde{\kappa}_{0^+}^{ZX}$, and $c_{TY}$.
+Although, these limits are several orders of magnitude larger than the current
+best limits, they demonstrate the feasibility of using Compton asymmetry for
+tests of Lorentz invariance. Future parity violating electron scattering
+experiments at Jefferson Lab will use higher energy electrons enabling better
+constraints.",1611.09173v1
+2016-11-29,Domain wall profiles in Co/Ir$_n$/Pt(111) ultrathin films: influence of the Dzyaloshinskii-Moriya interaction,"We perform a study of domain walls in Co/Ir$_n$/Pt(111) (n = 0,1,...,6) films
+by a combined approach of first-principles calculations and spin dynamics
+simulations. We determine the tensorial exchange interactions and the magnetic
+anisotropies for the Co overlayer in both FCC and HCP geometries, depending on
+the number of Ir buffer layers. We find strong ferromagnetic nearest-neighbor
+isotropic exchange interactions between the Co atoms and an out-of-plane
+magnetic anisotropy for the films in FCC geometry. Our simulations show that
+the magnetic domain walls are of N\'eel type, and their rotational sense
+(chirality) is changed upon the insertion of an Ir buffer layer as compared to
+the pristine Co/Pt(111) system. Our spin dynamics simulations indicate a
+twisting of the spins with respect to the planar domain wall profile on the
+triangular lattice. We discuss this domain wall twisting using symmetry
+arguments and in terms of an appropriate micromagnetic continuum model
+considering extra energy terms compared to the available literature.",1611.09518v1
+2016-11-29,Observation of wavelength-dependent Brewster angle shift in 3D photonic crystals,"The interaction of polarized light with photonic crystals exhibit unique
+features due to its sub-wavelength nature on the surface and the periodic
+variation of refractive index in the depth of the crystals. Here, we present a
+detailed study of polarization anisotropy in light scattering associated with
+three-dimensional photonic crystals with face centered cubic symmetry over a
+broad wavelength and angular range. The polarization anisotropy leads to a
+shift in the conventional Brewster angle defined for a planar interface with
+certain refractive index. The observed shift in Brewster angle strongly depends
+on the index contrast and lattice constant. Polarization-dependent stop gap
+measurements are performed on photonic crystals with different index contrast
+and lattice constants. These measurements indicate unique stop gap branching at
+high-symmetry points in the Brillouin zone of the photonic crystals. The
+inherited stop gap branching is observed for TE polarization whereas that is
+suppressed for TM polarization as a consequence of Brewster effect. Our results
+have consequences in the polarized light-scattering from plasmonic structures
+and dielectric meta-surfaces and are also useful in applications like
+nano-scale polarization splitters and lasers.",1611.09693v1
+2016-11-29,CoMET: Composite-Input Magnetoelectric-based Logic Technology,"This work proposes CoMET, a fast and energy-efficient spintronics device for
+logic applications. An input voltage is applied to a ferroelectric (FE)
+material, in contact with a composite structure - a ferromagnet (FM) with
+in-plane magnetic anisotropy (IMA) placed on top of an intra-gate FM
+interconnect with perpendicular magnetic anisotropy (PMA). Through the
+magnetoelectric (ME) effect, the input voltage nucleates a domain wall (DW) at
+the input end of the PMA-FM interconnect. An applied current then rapidly
+propagates the DW towards the output FE structure, where the inverse-ME effect
+generates an output voltage. This voltage is propagated to the input of the
+next CoMET device using a novel circuit structure that enables efficient device
+cascading. The material parameters for CoMET are optimized by systematically
+exploring the impact of parameter choices on device performance. Simulations on
+a 7nm CoMET device show fast, low-energy operation, with a delay/energy of
+98ps/68aJ for INV and 135ps/85aJ for MAJ3.",1611.09714v3
+2016-12-02,Mechanisms for strong anisotropy of in-plane g-factors in hole based quantum point contacts,"In-plane hole g-factors measured in quantum point contacts based on p-type
+heterostructures strongly depend on the orientation of the magnetic field with
+respect to the electric current. This effect, first reported a decade ago and
+confirmed in a number of publications, has remained an open problem. In this
+work, we present systematic experimental studies to disentangle different
+mechanisms contributing to the effect and develop the theory which describes it
+successfully. We show that there is a new mechanism for the anisotropy related
+to the existence of an additional $B_+k_-^4\sigma_+$ effective Zeeman
+interaction for holes, which is kinematically different from the standard
+single Zeeman term $B_-k_-^2\sigma_+$ considered until now.",1612.00572v2
+2016-12-02,FW/CADIS-$Ω$: An angle-informed hybrid method for deep-penetration radiation transport,"A new method for generating variance reduction parameters for strongly
+anisotropic, deep-penetration radiation shielding studies is presented. This
+method generates an alternate form of the adjoint scalar flux quantity,
+$\phi^{\dagger}_{\Omega}$, which is used by both CADIS and FW-CADIS to generate
+variance reduction parameters for local and global response functions,
+respectively. The new method, called CADIS-$\Omega$, was implemented in the
+Denovo/ADVANTG software suite, and results are presented for a concrete
+labyrinth test problem. Results indicate that the flux generated by
+CADIS-$\Omega$ incorporates localized angular anisotropies in the flux
+effectively. CADIS-$\Omega$ outperformed CADIS in the test problem while
+obtaining accurate results. This initial work indicates that CADIS-$\Omega$ may
+be highly useful for shielding problems with strong angular anisotropies. A
+future test plan to fully characterize the new method is proposed, which should
+reveal more about the types of realistic problems for which the CADIS-$\Omega$
+will be suited.",1612.00793v1
+2016-12-03,Anisotropic magneto-transport and magnetic properties of low temperature phase of TaTe2,"TaTe2 is a quasi-2D charge density wave (CDW) compound with distorted-1T type
+structure exhibiting double-zigzag chains. Here we report the Fermi surface
+topology of low temperature phase of TaTe2 (LT-TaTe2) by anisotropic
+magneto-transport and magnetic measurements on high-quality single crystals. An
+anomalous large linear magnetoresistance up to 140% at 3 K in 9 T was observed,
+suggesting the existence of a small Fermi pocket in Dirac cone state in quantum
+transport models. Meanwhile, strong magnetic anisotropy was observed for B
+(001) and B//(001). Angle-dependent magnetoresistance and de Hass-van Alphen
+oscillations suggest the anisotropy of the normal Fermi surface and the small
+Fermi pocket in Dirac cone state.",1612.00938v1
+2016-12-05,Spatial Anisotropy in Nonrelativistic Holography,"We examine holographic theories where Lifshitz symmetry is broken with
+spatial anisotropy. In particular, we focus on the conditions imposed by the
+null energy condition, and demonstrate that it is possible to have unusual
+anisotropic fixed points where a subset of the spatial dimensions have negative
+scaling exponents. We also construct interpolating solutions between UV and IR
+fixed points and show that there is essentially no restriction placed on the
+endpoints of the flow once anisotropic scaling is allowed. As an example, we
+demonstrate a flow from AdS to AdS with $c_{IR}>c_{UV}$ that is allowed by the
+null energy condition since it proceeds through an intermediate
+Lorentz-violating region. Finally, we examine the holographic Green's function
+in anisotropic Lifshitz spacetimes.",1612.01557v2
+2016-12-12,Polarization anisotropy of the emission from type-II quantum dots,"We study the polarization response of the emission from type-II GaAsSb capped
+InAs quantum dots. The theoretical prediction based on the calculations of the
+overlap integrals of the single-particle states obtained in the k.p framework
+is given. This is verified experimentally by polarization resolved
+photoluminescence measurements on samples with the type-II confinement. We show
+that the polarization anisotropy might be utilized to find the vertical
+position of the hole wavefunction and its orientation with respect to
+crystallographic axes of the sample. A proposition for usage in the information
+technology as a room temperature photonic gate operating at the communication
+wavelengths as well as a simple model to estimate the energy of fine-structure
+splitting for type-II GaAsSb capped InAs QDs are given.",1612.03585v1
+2016-12-21,Magnetotransport studies of Superconducting Pr$_4$Fe$_2$As$_2$Te$_{1-x}$O$_4$,"We report a detailed study of the electrical transport properties of single
+crystals of Pr$_4$Fe$_2$As$_2$Te$_{1-x}$O$_4$, a recently discovered iron-based
+superconductor. Resistivity, Hall effect and magnetoresistance are measured in
+a broad temperature range revealing the role of electrons as dominant charge
+carriers. The significant temperature dependence of the Hall coefficient and
+the violation of Kohler's law indicate multiband effects in this compound. The
+upper critical field and the magnetic anisotropy are investigated in fields up
+to 16 T, applied parallel and perpendicular to the crystallographic c-axis.
+Hydrostatic pressure up to 2 GPa linearly increases the critical temperature
+and the resistivity residual ratio. A simple two-band model is used to describe
+the transport and magnetic properties of Pr$_4$Fe$_2$As$_2$Te$_{1-x}$O$_4$. The
+model can successfully explain the strongly temperature dependent negative Hall
+coefficient and the high magnetic anisotropy assuming that the mobility of
+electrons is higher than that of holes.",1612.07090v1
+2017-01-02,In-Plane Anisotropies of Polarized Raman Response and Electrical Conductivity in Layered Tin Selenide,"The group IV-VI compound SnSe, with an orthorhombic lattice structure, has
+recently attracted particular interest due to its unexpectedly low thermal
+conductivity and high power factor, showing great promise for thermoelectric
+applications. SnSe displays intriguing anisotropic properties due to the
+puckered low-symmetry in-plane lattice structure. Low-dimensional materials
+have potential advantages in improving the efficiency of thermoelectric
+conversion, due to the increased power factor and decreased thermal
+conductivity. A complete study of the optical and electrical anisotropies of
+SnSe nanostructures is a necessary prerequisite in taking advantage of the
+material properties for high performance devices. Here, we synthesize the
+single crystal SnSe nanoplates (NPs) by chemical vapor deposition. The angular
+dependence of the polarized Raman spectra of SnSe NPs shows anomalous
+anisotropic light-mater interaction. The angle-resolved charge transport of the
+SnSe NPs expresses a strong anisotropic conductivity behavior. These studies
+elucidate the anisotropic interactions which will be of use for future
+ultrathin SnSe in electronic, thermoelectric and optoelectronic devices.",1701.00310v1
+2017-01-05,Excitation and detection of short-waved spin waves in ultrathin Ta/CoFeB/MgO-layer system suitable for spin-orbit-torque magnonics,"We report on the excitation and detection of short-waved spin waves with wave
+vectors up to about $40\,\mathrm{rad}\,\mu\mathrm{m}^{-1}$ in spin-wave
+waveguides made from ultrathin, in-plane magnetized Co$_{8}$Fe$_{72}$B$_{20}$
+(CoFeB). The CoFeB is incorporated in a layer stack of Ta/CoFeB/Mgo, a layer
+system featuring large spin orbit torques and a large perpendicular magnetic
+anisotropy constant. The short-waved spin waves are excited by nanometric
+coplanar waveguides and are detected via spin rectification and microfocussed
+Brillouin light scattering spectroscopy. We show that the large perpendicular
+magnetic anisotropy benefits the spin-wave lifetime greatly, resulting in a
+lifetime comparable to bulk systems without interfacial damping. The presented
+results pave the way for the successful extension of magnonics to ultrathin
+asymmetric layer stacks featuring large spin orbit torques.",1701.01399v1
+2017-01-07,Measurement of $D^0$ Meson Production and Azimuthal Anisotropy in Au+Au Collisions at $\sqrt{s_{NN}}$ = 200 GeV,"Due to the large masses, heavy-flavor quarks are dominantly produced in
+initial hard scattering processes and experience the whole evolution of the
+medium produced in heavy-ion collisions at RHIC energies. They are also
+expected to thermalize slower than light-flavor quarks. Thus the measurement of
+heavy quark production and azimuthal anisotropy can provide important insights
+into the medium properties through their interactions with the medium.
+  In these proceedings, we report measurements of $D^0$ production and elliptic
+flow ($v_2$) via topological reconstruction using STAR's recently installed
+Heavy Flavor Tracker (HFT). The new measurement of the nuclear modification
+factor ($R_{AA}$) of $D^0$ mesons in central Au+Au collisions at
+$\sqrt{s_{NN}}$ = 200 GeV confirms the strong suppression at high transverse
+momenta ($p_{T}$) reported in the previous publication with much improved
+precision. We also report the measurement of elliptic flow for $D^0$ mesons in
+a wide transverse momentum range in 0-80% minimum-bias Au+Au collisions. The
+$D^0$ elliptic flow is finite for $p_{T}$ $>$ 2 GeV/c and is systematically
+below that of light hadrons in the same centrality interval. Furthermore,
+several theoretical calculations are compared to both $R_{AA}$ and $v_2$
+measurements, and the charm quark diffusion coefficient is inferred to be
+between 2 and $\sim$12.",1701.01878v1
+2017-01-11,a-b anisotropy of the intra-unit-cell magnetic order in $\rm YBa_2Cu_3O_{6.6}$,"Within the complex phase diagram of the hole-doped cuprates, seizing the
+nature of the mysterious pseudo-gap phase is essential to unravel the
+microscopic origin of high-temperature superconductivity. Below the pseudo-gap
+temperature $\rm T^{\star}$, evidences for intra-unit-cell orders breaking the
+4-fold rotation symmetry have been provided by neutron diffraction and scanning
+tunneling spectroscopy. Using polarized neutron diffraction on a detwinned $\rm
+YBa_2Cu_3O_{6.6}$ sample, we here report a distinct a-b anisotropy of the
+intra-unit-cell magnetic structure factor below $\rm T^{\star}$, highlighting
+that intra-unit-cell order in this material breaks the mirror symmetry of the
+CuO$_2$ bilayers. This is likely to originate from a crisscrossed arrangement
+of loop currents within the $\rm CuO_2$ bilayer, resulting in a bilayer mean
+toroidal axis along the $\rm {\bf b}$ direction.",1701.02866v1
+2017-01-11,Amplitude limits and nonlinear damping of shear-Alfvén waves in high-beta low-collisionality plasmas,"This work, which extends Squire et al. [ApJL, 830 L25 (2016)], explores the
+effect of self-generated pressure anisotropy on linearly polarized
+shear-Alfv\'en fluctuations in low-collisionality plasmas. Such anisotropies
+lead to stringent limits on the amplitude of magnetic perturbations in
+high-beta plasmas, above which a fluctuation can destabilize itself through the
+parallel firehose instability. This causes the wave frequency to approach zero,
+""interrupting"" the wave and stopping its oscillation. These effects are
+explored in detail in the collisionless and weakly collisional ""Braginskii""
+regime, for both standing and traveling waves. The focus is on simplified
+models in one dimension, on scales much larger than the ion gyroradius. The
+effect has interesting implications for the physics of magnetized turbulence in
+the high-beta conditions that are prevalent in many astrophysical plasmas.",1701.03175v1
+2017-01-13,Proton fire hose instabilities in the expanding solar wind,"Using two-dimensional hybrid expanding box simulations we study the
+competition between the continuously driven parallel proton temperature
+anisotropy and fire hose instabilities in collisionless homogeneous plasmas.
+For quasi radial ambient magnetic field the expansion drives
+$T_{\mathrm{p}\|}>T_{\mathrm{p}\perp}$ and the system becomes eventually
+unstable with respect to the dominant parallel fire hose instability. This
+instability is generally unable to counteract the induced anisotropization and
+the system typically becomes unstable with respect to the oblique fire hose
+instability later on. The oblique instability efficiently reduces the
+anisotropy and the system rapidly stabilizes while a significant part of the
+generated electromagnetic fluctuations is damped to protons. As long as the
+magnetic field is in the quasi radial direction, this evolution repeats itself
+and the electromagnetic fluctuations accumulate. For sufficiently oblique
+magnetic field the expansion drives $T_{\mathrm{p}\perp}>T_{\mathrm{p}\|}$ and
+brings the system to the stable region with respect to the fire hose
+instabilities.",1701.03665v1
+2017-01-18,Anisotropic Dzyaloshinskii-Moriya Interaction in ultra-thin epitaxial Au/Co/W(110),"We have used Brillouin Light Scattering spectroscopy to independently
+determine the in-plane Magneto-Crystalline Anisotropy and the
+Dzyaloshinskii-Moriya Interaction (DMI) in out-of-plane magnetized
+Au/Co/W(110). We found that the DMI strength is 2-3 times larger along the
+bcc$[\bar{1}10]$ than along the bcc$[001]$ direction. We use analytical
+considerations to illustrate the relationship between the crystal symmetry of
+the stack and the anisotropy of microscopic DMI. Such an anisotropic DMI is the
+first step to realize isolated elliptical skyrmions or anti-skyrmions in thin
+film systems with $C_{2v}$ symmetry.",1701.05062v2
+2017-01-19,Linear Stability Analysis of a Levitated Nanomagnet in a Static Magnetic Field: Quantum Spin Stabilized Magnetic Levitation,"We theoretically study the levitation of a single magnetic domain nanosphere
+in an external static magnetic field. We show that apart from the stability
+provided by the mechanical rotation of the nanomagnet (as in the classical
+Levitron), the quantum spin origin of its magnetization provides two additional
+mechanisms to stably levitate the system. Despite of the Earnshaw theorem, such
+stable phases are present even in the absence of mechanical rotation. For large
+magnetic fields, the Larmor precession of the quantum magnetic moment
+stabilizes the system in full analogy with magnetic trapping of a neutral atom.
+For low magnetic fields, the magnetic anisotropy stabilizes the system via the
+Einstein-de Haas effect. These results are obtained with a linear stability
+analysis of a single magnetic domain rigid nanosphere with uniaxial anisotropy
+in a Ioffe-Pritchard magnetic field.",1701.05410v3
+2017-01-23,Understanding stability diagram of perpendicular magnetic tunnel junctions,"Perpendicular magnetic tunnel junctions (MTJ) with a bottom pinned reference
+layer and a composite free layer (FL) are investigated. Different thicknesses
+of the FL were tested to obtain an optimal balance between tunneling
+magnetoresistance (TMR) ratio and perpendicular magnetic anisotropy. After
+annealing at 400 $^\circ$C, the TMR ratio for 1.5 nm thick CoFeB sublayer
+reached 180 % at room temperature and 280 % at 20 K with an MgO tunnel barrier
+thickness corresponding to the resistance area product RA = 10
+Ohm$\mathrm{\mu}$m$^2$. The voltage vs. magnetic field stability diagrams
+measured in pillar-shaped MTJs with 130 nm diameter indicate the competition
+between spin transfer torque (STT), voltage controlled magnetic anisotropy
+(VCMA) and temperature effects in the switching process. An extended stability
+phase diagram model that takes into account all three parameters and the
+effective damping measured independently using broadband ferromagnetic
+resonance technique enabled the determination of both STT and VCMA coefficients
+that are responsible for the FL magnetization switching.",1701.06411v1
+2017-01-26,Mechanism for nematic superconductivity in FeSe,"Despite its seemingly simple composition and structure, the pairing mechanism
+of FeSe remains an open problem due to several striking phenomena. Among them
+are nematic order without magnetic order, nodeless gap and unusual inelastic
+neutron spectra with a broad continuum, and gap anisotropy consistent with
+orbital selection of unknown origin. Here we propose a microscopic description
+of a nematic quantum spin liquid that reproduces key features of neutron
+spectra. We then study how the spin fluctuations of the local moments lead to
+pairing within a spin-fermion model. We find the resulting superconducting
+order parameter to be nodeless $s\pm d$-wave within each domain. Further we
+show that orbital dependent Hund's coupling can readily capture observed gap
+anisotropy. Our prediction calls for inelastic neutron scattering in a
+detwinned sample.",1701.07813v2
+2017-01-30,Quantum dynamics of a domain wall in a quasi one-dimensional $XXZ$ ferromagnet,"We derive an effective low-energy theory for a ferromagnetic $(2N+1)$-leg
+spin-$\frac{1}{2}$ ladder with strong $XXZ$ anisotropy
+$\left|J_{\parallel}^z\right|\ll \left|J_{\parallel}^{xy}\right|$, subject to a
+kink-like non-uniform magnetic field $B_z(X)$ which induces a domain wall (DW).
+Using Bosonization of the quantum spin operators, we show that the quantum
+dynamics is dominated by a single one-dimensional mode, and is described by a
+sine-Gordon model. The parameters of the effective model are explored as
+functions of $N$, the easy-plane anisotropy
+$\Delta=-J_{\parallel}^z/J_{\parallel}^{xy}$, and the strength and profile of
+the transverse field $B_z(X)$. We find that at sufficiently strong and
+asymmetric field, this mode may exhibit a quantum phase transition from a
+Luttinger liquid to a spin-density-wave (SDW) ordered phase. As the effective
+Luttinger parameter grows with the number of legs in the ladder ($N$), the SDW
+phase progressively shrinks in size, recovering the gapless dynamics expected
+in the two-dimensional limit $N\rightarrow\infty$.",1701.08556v1
+2017-02-01,Anisotropic hydrodynamic turbulence in accretion disks,"Recently, the vertical shear instability (VSI) has become an attractive
+purely hydrodynamic candidate for the anomalous angular momentum transport
+required for weakly ionized accretion disks. In direct three-dimensional
+numerical simulations of VSI turbulence in disks, a meridional circulation
+pattern was observed that is opposite to the usual viscous flow behavior. Here,
+we investigate whether this feature can possibly be explained by an anisotropy
+of the VSI turbulence. Using three-dimensional hydrodynamical simulations, we
+calculate the turbulent Reynolds stresses relevant for angular momentum
+transport for a representative section of a disk.
+  We find that the vertical stress is significantly stronger than the radial
+stress. Using our results in viscous disk simulations with different viscosity
+coefficients for the radial and vertical direction, we find good agreement with
+the VSI turbulence for the stresses and meridional flow; this provides
+additional evidence for the anisotropy. The results are important with respect
+to the transport of small embedded particles in disks.",1702.00334v2
+2017-02-02,Isotropization of two-dimensional hydrodynamic turbulence in the direct cascade,"We present results of numerical simulation of the direct cascade in
+two-dimensional hydrodynamic turbulence (with spatial resolution up to $16384
+\times 16384$). If at the earlier stage (at the time of order of the inverse
+pumping growth rate $\tau\sim\Gamma_{max}^{-1}$), the turbulence develops
+according to the same scenario as in the case of a freely decaying turbulence
+\cite{KNNR-07, KKS}: quasi-singular distributions of di-vorticity are formed,
+which in $k$-space correspond to jets, leading to a strong turbulence
+anisotropy, then for times of the order of $10\tau$ turbulence becomes almost
+isotropic. In particular, at these times any significant anisotropy in the
+angular fluctuations for the energy spectrum (for a fixed $k$) is not visible,
+while the probability distribution function of vorticity for large arguments
+has the exponential tail with the exponent linearly dependent on vorticity, in
+the agreement with the theoretical prediction \cite{FalkovichLebedev2011}.",1702.00738v1
+2017-02-06,Temperature induced phase transition from cycloidal to collinear antiferromagnetism in multiferroic Bi$_{0.9}$Sm$_{0.1}$FeO$_3$ driven by $f$-$d$ induced magnetic anisotropy,"In multiferroic BiFeO$_3$ a cycloidal antiferromagnetic structure is coupled
+to a large electric polarization at room temperature, giving rise to
+magnetoelectric functionality that may be exploited in novel multiferroic-based
+devices. In this paper, we demonstrate that by substituting samarium for 10% of
+the bismuth ions the periodicity of the room temperature cycloid is increased,
+and by cooling below $\sim15$ K the magnetic structure tends towards a simple
+G-type antiferromagnet, which is fully established at 1.5 K. We show that this
+transition results from $f-d$ exchange coupling, which induces a local
+anisotropy on the iron magnetic moments that destroys the cycloidal order - a
+result of general significance regarding the stability of non-collinear
+magnetic structures in the presence of multiple magnetic sublattices.",1702.01635v1
+2017-02-07,Magnetic domains in thin ferromagnetic films with strong perpendicular anisotropy,"We investigate the scaling of the ground state energy and optimal domain
+patterns in thin ferromagnetic films with strong uniaxial anisotropy and the
+easy axis perpendicular to the film plane. Starting from the full
+three-dimensional micromagnetic model, we identify the critical scaling where
+the transition from single domain to multidomain ground states such as bubble
+or maze patterns occurs. Furthermore, we analyze the asymptotic behavior of the
+energy in two regimes separated by a transition. In the single domain regime,
+the energy $\Gamma$-converges towards a much simpler two-dimensional and local
+model. In the second regime, we derive the scaling of the minimal energy and
+deduce a scaling law for the typical domain size.",1702.01980v1
+2017-02-09,Microscopic origin of ideal conductivity in integrable quantum models,"Non-ergodic dynamical systems display anomalous transport properties. A
+prominent example are integrable quantum systems, whose exceptional property
+are diverging DC conductivities. In this Letter, we explain the microscopic
+origin of ideal conductivity by resorting to the thermodynamic particle content
+of a system. Using group-theoretic arguments we rigorously resolve the
+long-standing controversy regarding the nature of spin and charge Drude weights
+in the absence of chemical potentials. In addition, by employing a hydrodynamic
+description, we devise an efficient computational method to calculate exact
+Drude weights from the stationary currents generated in an inhomogeneous quench
+from bi-partitioned initial states. We exemplify the method on the anisotropic
+Heisenberg model at finite temperatures for the entire range of anisotropies,
+accessing regimes which are out of reach with other approaches. Quite
+remarkably, spin Drude weight and asymptotic spin current rates reveal a
+completely discontinuous (fractal) dependence on the anisotropy parameter.",1702.02930v2
+2017-02-13,Cytoskeletal Anisotropy Controls Geometry and Forces of Adherent Cells,"We investigate the geometrical and mechanical properties of adherent cells
+characterized by a highly anisotropic actin cytoskeleton. Using a combination
+of theoretical work and experiments on micropillar arrays, we demonstrate that
+the shape of the cell edge is accurately described by elliptical arcs, whose
+eccentricity expresses the degree of anisotropy of the internal cell stresses.
+This results in a spatially varying tension along the cell edge, that
+significantly affects the traction forces exerted by the cell on the substrate.
+Our work highlights the strong interplay between cell mechanics and geometry
+and paves the way towards the reconstruction of cellular forces from
+geometrical data.",1702.03916v2
+2017-02-22,Universal scaling and critical exponents of the anisotropic quantum Rabi model,"We investigate first- and second-order quantum phase transitions of the
+anisotropic quantum Rabi model, in which the rotating- and counter-rotating
+terms are allowed to have different coupling strength. The model interpolates
+between two known limits with distinct universal properties. Through a
+combination of analytic and numerical approaches we extract the phase diagram,
+scaling functions, and critical exponents, which allows us to establish that
+the universality class at finite? anisotropy is the same as the isotropic
+limit. We also reveal other interesting features, including a
+superradiance-induced freezing of the effective mass and discontinuous scaling
+functions in the Jaynes-Cummings limit. Our findings are relevant in a variety
+of systems able to realize strong coupling between light and matter, such as
+circuit QED setups where a finite anisotropy appears quite naturally.",1702.06641v1
+2017-02-23,Spin-Orbit Coupling of Conduction Electrons in Magnetization Switching,"Strong magnetic field pulses associated with a relativistic electron bunch
+can imprint switching patterns in magnetic thin films that have uniaxial
+in-plane anisotropy. In experiments with Fe and FeCo alloy films the pattern
+shape reveals an additional torque acting on magnetization during the short (in
+the 100fs time scale) magnetic field pulse. The magnitude of the torque is as
+high as 15% of the torque from the magnetic field. The torque symmetry is that
+of a uniaxial anisotropy along the direction of the eddy current screening the
+magnetic field. Spin-orbit interaction acting on the conduction electrons can
+produce such a torque with the required symmetry and magnitude. The same
+interaction causes the anomalous Hall current to be spin-polarized, exerting a
+back reaction on magnetization direction. Such a mechanism may be at work in
+all-optical laser switching of magnetic materials.",1702.07153v1
+2017-02-27,Unusual enhancement of effective magnetic anisotropy with decreasing particle size in maghemite nanoparticles,"Experimental results and a model are presented to explain the observed
+unusual enhancement of the effective magnetic anisotropy Keff with decreasing
+particle size D from 15 nm to 2.5 nm in {\gamma}-Fe2O3 nanoparticles (NPs). The
+samples include oleic acid-coated NPs with D = 2.5, 3.4, 6.3 and 7.0 nm
+investigated here, with the results on other sizes taken from literature. Keff
+is determined from the analysis of the frequency dependence of the blocking
+temperature TB after considering the effects of interparticle interactions on
+TB. The data of Keff vs. D is fit to the derived core-shell-based relation:
+Keff = Kb + (6KS/D) +Ksh{[1-(2d/D)]^(-3) -1}, with Kb = 1.9 x10^5 ergs/cm^3 as
+the bulk-like contribution of the core, KS = 0.035 ergs/cm^2 as the
+contribution of the surface layer, and Ksh = 1.057 x10^4 ergs/cm^3 as the
+contributions of spins in the shell of thickness d = 1.1 nm. This equation
+represents an extension of the often-used Eq.: Keff = Kb + (6KS/D).
+Significance of this new result is discussed.",1702.08378v1
+2017-02-28,An a posteriori error analysis for a coupled continuum pipe-flow/Darcy model in Karst aquifers: anisotropic and isotropic discretizations,"This paper presents an a posteriori error analysis for a coupled continuum
+pipe-flow/Darcy model in karst aquifers. We consider a unified anisotropic
+finite element discretization (i.e. elements with very large aspect ratio). Our
+analysis covers two-dimensional domains, conforming and nonconforming
+discretizations as well as different elements. Many examples of finite elements
+that are covered by analysis are presented. From the finite element solution,
+the error estimators are constructed and based on the residual of model
+equations. Lower and upper error bounds form the main result with minimal
+assumptions on the elements. The lower error bound is uniform with respect to
+the mesh anisotropy in the entire domain. The upper error bound depends on a
+proper alignment of the anisotropy of the mesh which is a common feature of
+anisotropic error estimation. In the special case of isotropic meshes, the
+results simplify, and upper and lower error bounds hold unconditionally.",1702.08814v2
+2017-03-15,Domain engineering of the metastable domains in the 4f-uniaxial-ferromagnet CeRu$_2$Ga$_2$B,"In search of novel, improved materials for magnetic data storage and
+spintronic devices, compounds that allow a tailoring of magnetic domain shapes
+and sizes are essential. Good candidates are materials with intrinsic
+anisotropies or competing interactions, as they are prone to host various
+domain phases that can be easily and precisely selected by external tuning
+parameters such as temperature and magnetic field. Here, we utilize vector
+magnetic fields to visualize directly the magnetic anisotropy in the uniaxial
+ferromagnet CeRu$_2$Ga$_2$B. We demonstrate a feasible control both globally
+and locally of domain shapes and sizes by the external field as well as a
+smooth transition from single stripe to bubble domains, which opens the door to
+future applications based on magnetic domain tailoring.",1703.05228v1
+2017-03-21,Large anisotropic spin relaxation time of exciton bound to donor states in triple quantum wells,"We have studied the spin dynamics of a dense two-dimensional electron gas
+confined in a GaAs/AlGaAs triple quantum well by using time-resolved Kerr
+rotation and resonant spin amplification. Strong anisotropy of the spin
+relaxation time up to a factor of 10 was found between the electron spins
+oriented in-plane and out-of-plane when the excitation energy is tuned to an
+exciton bound to neutral donor transition. We model this anisotropy using an
+internal magnetic field and the inhomogeneity of the electron g-factor. The
+data analysis allows us to determine the direction and magnitude of this
+internal field in the range of a few mT for our studied structure, which
+decreases with the sample temperature and optical power. The dependence of the
+anisotropic spin relaxation was directly measured as a function of several
+experimental parameters: excitation wavelength, sample temperature, pump-probe
+time delay, and pump power.",1703.07156v2
+2017-03-17,Mirror instability in the turbulent solar wind,"The relationship between a decaying strong turbulence and the mirror
+instability in a slowly expanding plasma is investigated using two-dimensional
+hybrid expanding box simulations. We impose an initial ambient magnetic field
+perpendicular to the simulation box, and we start with a spectrum of
+large-scale, linearly-polarized, random-phase Alfvenic fluctuations which have
+energy equipartition between kinetic and magnetic fluctuations and vanishing
+correlation between the two fields. A turbulent cascade rapidly develops,
+magnetic field fluctuations exhibit a Kolmogorov-like power-law spectrum at
+large scales and a steeper spectrum at sub-ion scales. The imposed expansion
+(taking a strictly transverse ambient magnetic field) leads to generation of an
+important perpendicular proton temperature anisotropy that eventually drives
+the mirror instability. This instability generates large-amplitude,
+nonpropagating, compressible, pressure-balanced magnetic structures in a form
+of magnetic enhancements/humps that reduce the perpendicular temperature
+anisotropy.",1703.07377v1
+2017-03-24,Unconventional superconductivity in the BiS$_2$-based layered superconductor NdO$_{0.71}$F$_{0.29}$BiS$_2$,"We investigate the superconducting-gap anisotropy in one of the recently
+discovered BiS$_2$-based superconductors, NdO$_{0.71}$F$_{0.29}$BiS$_2$ ($T_c$
+$\sim$ 5 K), using laser-based angle-resolved photoemission spectroscopy.
+Whereas the previously discovered high-$T_c$ superconductors such as copper
+oxides and iron-based superconductors, which are believed to have
+unconventional superconducting mechanisms, have $3d$ electrons in their
+conduction bands, the conduction band of BiS$_2$-based superconductors mainly
+consists of Bi 6$p$ electrons, and hence the conventional superconducting
+mechanism might be expected. Contrary to this expectation, we observe a
+strongly anisotropic superconducting gap. This result strongly suggests that
+the pairing mechanism for NdO$_{0.71}$F$_{0.29}$BiS$_2$ is unconventional one
+and we attribute the observed anisotropy to competitive or cooperative multiple
+paring interactions.",1703.08379v1
+2017-03-28,The influence of anti-site defects and stacking faults on the magneto crystalline anisotropy of FePt,"We present density functional theory (DFT) calculations of the magnetic
+anisotropy energy (MAE) of FePt, which is of great interest for magnetic
+recording applications. Our data, and the majority of previously calculated
+results for perfectly ordered crystals, predict an MAE of $\sim 3.0$ meV per
+formula unit, which is significantly larger than experimentally measured
+values. Analyzing the effects of disorder by introducing stacking faults (SFs)
+and anti site defects (ASDs) in varying concentrations we are able to reconcile
+calculations with experimental data and show that even a low concentration of
+ASDs are able to reduce the MAE of FePt considerably. Investigating the effect
+of exact exchange and electron correlation within the adiabatic-connection
+dissipation fluctuation theorem in the random phase approximation (ACDFT-RPA)
+reveals a significantly smaller influence on the MAE. Thus the effect of
+disorder, and more specifically ASDs, is the crucial factor in explaining the
+deviation of common DFT calculations of FePt to experimental measurements.",1703.09559v1
+2017-03-29,Magnon dispersion in Ca2RuO4: impact of spin-orbit coupling and oxygen moments,"The magnon dispersion of Ca$_2$RuO$_4$ has been studied by polarized and
+unpolarized neutron scattering experiments on crystals containing 0, 1 and 10 %
+of Ti. The entire dispersion of transverse magnons can be well described by a
+conventional spin-wave model with interaction and anisotropy parameters that
+agree with density functional theory calculations. Spin-orbit coupling strongly
+influences the magnetic excitations, which is most visible in large energies of
+the magnetic zone-center modes arising from magnetic anisotropy. We find
+evidence for a low-lying additional mode that exhibits strongest scattering
+intensity near the antiferromagnetic zone center. This extra signal can be
+explained by a sizable magnetic moment of 0.11 Bohr magnetons on the apical
+oxygens parallel to the Ru moment, which is found in the density functional
+theory calculations. The energy and the signal strength of the additional
+branch are well described by taking into account this oxygen moment with weak
+ferromagnetic coupling between Ru and O moments.",1703.10017v1
+2017-03-31,Temperature Dependence of the Anisotropy Field of L10 FePt near the Curie Temperature,"Near the Curie temperature the anisotropy field of magnetically uniaxial L10
+FePt is expected to follow the scaling law $(1-T/Tc)^\beta$ where $T$ is the
+temperature and $T_c$ the Curie temperature. In the literature $\beta$ values
+between 0.36 and 0.65 have been reported. Based on recording measurements and
+micromagnetic analysis, we show that only the values of $\beta$ near the low
+end of the reported range are compatible with the data. We also conclude that
+thermally activated magnetization reversal at temperatures near $T_c$ cannot be
+ignored, even at time scales smaller than 1 ns. We demonstrate that thermally
+activated magnetization reversal at temperatures close to $T_c$ is well
+described by conventional theory with a frequency factor $f_0$ of the order of
+$10^{12}$ Hz. It is reasoned that the unusually high value for $f_0$ is a
+consequence of the temperature-induced reduction of the degree of alignment of
+the micro-spins within the grains.",1703.10921v1
+2017-04-01,Asymmetric isolated skyrmions in polar magnets with easy-plane anisotropy,"We introduce a new class of isolated magnetic skyrmions emerging within
+tilted ferromagnetic phases of polar magnets with easy-plane anisotropy. The
+asymmetric magnetic structure of these skyrmions is associated with an
+intricate pattern of the energy density, which exhibits positive and negative
+asymptotics with respect to the surrounding state with a ferromagnetic moment
+tilted away from the polar axis. Correspondingly, the skyrmion-skyrmion
+interaction has an anisotropic character and can be either attractive or
+repulsive depending on the relative orientation of the skyrmion pair. We
+investigate the stability of these novel asymmetric skyrmions against the
+elliptical cone state and follow their transformation into axisymmetric
+skyrmions, when the tilted ferromagnetic moment of the host phase is reduced.
+Our theory gives clear directions for experimental studies of isolated
+asymmetric skyrmions and their clusters embedded in tilted ferromagnetic
+phases.",1704.00100v1
+2017-04-05,Isotropic reconstruction of 3D fluorescence microscopy images using convolutional neural networks,"Fluorescence microscopy images usually show severe anisotropy in axial versus
+lateral resolution. This hampers downstream processing, i.e. the automatic
+extraction of quantitative biological data. While deconvolution methods and
+other techniques to address this problem exist, they are either time consuming
+to apply or limited in their ability to remove anisotropy. We propose a method
+to recover isotropic resolution from readily acquired anisotropic data. We
+achieve this using a convolutional neural network that is trained end-to-end
+from the same anisotropic body of data we later apply the network to. The
+network effectively learns to restore the full isotropic resolution by
+restoring the image under a trained, sample specific image prior. We apply our
+method to $3$ synthetic and $3$ real datasets and show that our results improve
+on results from deconvolution and state-of-the-art super-resolution techniques.
+Finally, we demonstrate that a standard 3D segmentation pipeline performs on
+the output of our network with comparable accuracy as on the full isotropic
+data.",1704.01510v1
+2017-04-06,A critical study of the elastic properties and stability of Heusler compounds: Phase change and tetragonal $X_{2}YZ$ compounds,"In the present work, the elastic constants and derived properties of
+tetragonal and cubic Heusler compounds were calculated using the high accuracy
+of the full-potential linearized augmented plane wave (FPLAPW). To find the
+criteria required for an accurate calculation, the consequences of increasing
+the numbers of $k$-points and plane waves on the convergence of the calculated
+elastic constants were explored. Once accurate elastic constants were
+calculated, elastic anisotropies, sound velocities, Debye temperatures,
+malleability, and other measurable physical properties were determined for the
+studied systems. The elastic properties suggested metallic bonding with
+intermediate malleability, between brittle and ductile, for the studied Heusler
+compounds. To address the effect of off-stoichiometry on the mechanical
+properties, the virtual crystal approximation (VCA) was used to calculate the
+elastic constants. The results indicated that an extreme correlation exists
+between the anisotropy ratio and the stoichiometry of the Heusler compounds,
+especially in the case of Ni$_{2}$MnGa.",1704.01741v1
+2017-04-10,Symmetry protected topological Luttinger liquids and the phase transition between them,"We show that a doped spin-1/2 ladder with antiferromagnetic intra-chain and
+ferromagnetic inter-chain coupling is a symmetry protected topologically
+non-trivial Luttinger liquid. Turning on a large easy-plane spin anisotropy
+drives the system to a topologically-trivial Luttinger liquid. Both phases have
+full spin gaps and exhibit power-law superconducting pair correlation. The
+Cooper pair symmetry is singlet $d_{xy}$ in the non-trivial phase and triplet
+$S_z=0$ in the trivial phase. The topologically non-trivial Luttinger liquid
+exhibits gapless spin excitations in the presence of a boundary, and it has no
+non-interacting or mean-field theory analog even when the fluctuating phase in
+the charge sector is pinned. As a function of the strength of spin anisotropy
+there is a topological phase transition upon which the spin gap closes. We
+speculate these Luttinger liquids are relevant to the superconductivity in
+metalized integer spin ladders or chains.",1704.02997v1
+2017-04-18,Strong anisotropic optical conductivity in two dimensional puckered structures: The role of Rashba effect,"We calculate the optical conductivity of an anisotropic two-dimensional
+system with Rashba spin-flip excitation within the Kubo formalism. We show that
+the anisotropic Rashba effect caused by an external field changes significantly
+the magnitude of the spin splitting. Furthermore, we obtain an analytical
+expression for the longitudinal optical conductivity associated with inter-band
+transitions as a function of the frequency for an arbitrary polarization angle.
+We find that the diagonal components of the optical conductivity tensor are
+direction-dependent and the spectrum of optical absorption is strongly
+anisotropic with an absorption window. The height and width of this absorption
+window are very sensitive to the system anisotropy. While the height of
+absorption peak increases with increasing effective mass anisotropy ratio, the
+peak intensity is larger when the light polarization is along the armchair
+direction. Moreover, the absorption peak width becomes broader as the density
+of state mass or Rashba interaction is enhanced. These features can be used to
+determine parameters relevant for spintronics through the optical absorption
+spectrum.",1704.05266v1
+2017-04-19,Anisotropic features in the electronic structure of the two-dimensional transition metal trichalcogenide TiS$_3$: electron doping and plasmons,"Analysis of the band structure of TiS$_3$ single-layers suggests the
+possibility of changing their physical behaviour by injecting electron
+carriers. The anisotropy of the valence and conduction bands is explained in
+terms of their complex orbital composition. The nature of the Fermi surface and
+Lindhard response function for different doping concentrations is studied by
+means of first-principles DFT calculations. It is suggested that for electron
+doping levels $x$ (number of electrons per unit cell) $\sim$ 0.18-0.30$e^-$ the
+system could exhibit incommensurate charge or spin modulations which, however,
+would keep the metallic state whereas systems doped with smaller $x$ would be
+2D metals without any electronic instability. The effect of spin-orbit coupling
+in the band dispersion is analysed. The DFT effective masses are used to study
+the plasmon spectrum from an effective low energy model. We find that this
+material supports highly anisotropic plasmons, with opposite anisotropy for the
+electron and hole bands.",1704.05824v1
+2017-04-20,Anisotropy of the astrophysical gravitational wave background: analytic expression of the angular power spectrum and correlation with cosmological observations,"Unresolved and resolved sources of gravitational waves are at the origin of a
+stochastic gravitational wave background. While the computation of its mean
+density as a function of frequency in a homogeneous and isotropic universe is
+standard lore, the computation of its anisotropies requires to understand the
+coarse graining from local systems, to galactic scales and then to cosmology.
+An expression of the gravitational wave energy density valid in any general
+spacetime is derived. It is then specialized to a perturbed
+Friedmann-Lema\^itre spacetime in order to determine the angular power spectrum
+of this stochastic background as well as its correlation with other
+cosmological probes, such as the galaxy number counts and weak lensing. Our
+result for the angular power spectrum also provides an expression for the
+variance of the gravitational wave background.",1704.06184v3
+2017-04-20,Photon and dilepton observables: An experimental overview,"Dilepton and direct photon measurements in heavy ion collisions provide
+access to the early stages of the collision. Dilepton continuum measurements at
+SPS and RHIC show an excess consistent with broadening of the rho meson
+spectral function as a result of hadronic interactions. Direct photon
+measurements at RHIC and the LHC show an excess of low $p_{T}$ photons over the
+expected yield. This excess has a large azimuthal anisotropy with respect to
+the collision plane. Understanding the direct photon excess and its anisotropy
+has become an outstanding question in the field of heavy ion physics. This
+proceeding consists of a summary of new dilepton and direct photon experimental
+results shown at the 2017 International Conference on Ultrarelativistic
+Nucleus-Nucleus Collisions and presents them in the context of our current
+understanding of these electromagentic probes.",1704.06307v3
+2017-04-21,Magnetic anisotropy and valence states in La$_2$Co$_{1-x}$Mn$_{1+x}$O$_6$ ($x\approx 0.23$) thin films studied by X-ray absorption spectroscopy techniques,"X-ray absorption spectroscopy was used to determine the valence state in
+La$_2$Co$_{1-x}$Mn$_{1+x}$O$_6$ ($x\approx 0.23$) thin films. We found that in
+spite of the non-stoichiometry, Co is in a divalent state while Mn ions show a
+mixed valence state. The relation of this finding with the magnetic properties
+of the films is discussed. X-ray magnetic circular dichroism measurements prove
+that magnetic anisotropy originates from Co spin-orbit coupling and it is
+strain-dependent: a strong increase of the angular contribution to the magnetic
+moment is found when in-plane (out-of-plane) and cell parameters get expanded
+(compressed). This behavior is reproduced by first order perturbation theory
+calculations.",1704.06411v1
+2017-04-25,Distinguishing XY from Ising Electron Nematics,"At low temperatures in ultraclean GaAs-AlGaAs heterojunctions, high
+fractional Landau levels break rotational symmetry, leading to increasingly
+anisotropic transport properties as temperature is lowered below $\sim$150mK.
+While the onset of transport anisotropy is well described by an XY model of an
+electron nematic in the presence of a weak uniform symmetry-breaking term, the
+low temperature behavior deviates significantly from this model. We find that
+inclusion of interactions between the electron nematic and the underlying
+crystalline lattice in the form of a 4-fold symmetry breaking term is
+sufficient to describe the entire temperature dependence of the transport
+anisotropy. This implies that the quantum Hall electron nematic is in the Ising
+universality class. We propose new experimental tests that can distinguish
+whether any two-dimensional electron nematic is in the XY or Ising universality
+class.",1704.07527v1
+2017-04-26,Transfer of magnetic order and anisotropy through epitaxial integration of 3$d$ and 4$f$ spin systems,"Resonant x-ray scattering at the Dy $M_5$ and Ni $L_3$ absorption edges was
+used to probe the temperature and magnetic field dependence of magnetic order
+in epitaxial LaNiO$_3$-DyScO$_3$ superlattices. For superlattices with 2 unit
+cell thick LaNiO$_3$ layers, a commensurate spiral state develops in the Ni
+spin system below 100 K. Upon cooling below $T_{ind} = 18$ K, Dy-Ni exchange
+interactions across the LaNiO$_3$-DyScO$_3$ interfaces induce collinear
+magnetic order of interfacial Dy moments as well as a reorientation of the Ni
+spins to a direction dictated by the strong magneto-crystalline anisotropy of
+Dy. This transition is reversible by an external magnetic field of 3 T.
+Tailored exchange interactions between rare-earth and transition-metal ions
+thus open up new perspectives for the manipulation of spin structures in
+metal-oxide heterostructures and devices.",1704.07967v1
+2017-04-28,Large magnetic anisotropy in quasi one-dimensional spin-1/2 fluoride antiferromagnets with a d(z2)1 ground state,"Hybrid density functional calculations are performed for a variety of systems
+containing d9 ions (Cu2+, Ag2+), and exhibiting quasi-one-dimensional magnetic
+properties. In particular we study fluorides containing these ions in a rarely
+encountered compressed octahedral coordination which forces the unpaired
+electron in the d(z2) orbital. We predict that such systems should exhibit
+magnetic anisotropies surpassing that of Sr2CuO3 - one of the best realizations
+of an one-dimensional system known to date. In particular we predict that the
+inter-chain coupling in the Ag2+ containing [AgF][BF4] should be nearly five
+orders of magnitude smaller than the intra-chain interaction. Our results
+indicate that quasi-one-dimensional spin-1/2 systems containing chains with
+spin sites in a d(z2)1 local ground state could constitute a versatile model
+for testing modern theories of quantum many-body physics in the solid state.",1704.08902v1
+2017-05-02,$z-$Weyl gravity in higher dimensions,"We consider higher dimensional gravity in which the four dimensional
+spacetime and extra dimensions are not treated on an equal footing. The
+anisotropy is implemented in the ADM decomposition of higher dimensional metric
+by requiring the foliation preserving diffeomorphism invariance adapted to the
+extra dimensions, thus keeping the general covariance only for the four
+dimensional spacetime. The conformally invariant gravity can be constructed
+with an extra (Weyl) scalar field and a real parameter $z$ which describes the
+degree of anisotropy of conformal transformation between the spacetime and
+extra dimensional metrics. In the zero mode effective 4D action, it reduces to
+four-dimensional scalar-tensor theory coupled with nonlinear sigma model
+described by extra dimensional metrics. There are no restrictions on the value
+of $z$ at the classical level and possible applications to the cosmological
+constant problem with a specific choice of $z$ is discussed.",1705.00866v2
+2017-05-11,Spin Dynamics and Magnetoelectric Coupling Mechanism of Co4Nb2O9,"Neutron powder diffraction experiments reveal that Co4Nb2O9 forms a
+noncollinear in-plane magnetic structure with Co2+ moments lying in the ab
+plane. The spin-wave excitations of this magnet were measured by using
+inelastic neutron scattering and soundly simulated by a dynamic model involving
+nearest and next-nearest neighbour exchange interactions, in-plane anisotropy
+and the Dzyaloshinskii-Moriya interaction. The in-plane magnetic structure of
+Co4Nb2O9 is attributed to the large in-plane anisotropy while the
+noncollinearity of the spin configuration is attributed to the
+Dzyaloshinskii-Moriya interaction. The high magnetoelectric coupling effect of
+Co4Nb2O9 in fields can be explained by its special in-plane magnetic structure.",1705.04017v3
+2017-05-24,Quantitative characterization of pore structure of several biochars with 3D imaging,"Pore space characteristics of biochars may vary depending on the used raw
+material and processing technology. Pore structure has significant effects on
+the water retention properties of biochar amended soils. In this work, several
+biochars were characterized with three-dimensional imaging and image analysis.
+X-ray computed microtomography was used to image biochars at resolution of 1.14
+$\mu$m and the obtained images were analysed for porosity, pore-size
+distribution, specific surface area and structural anisotropy. In addition,
+random walk simulations were used to relate structural anisotropy to diffusive
+transport. Image analysis showed that considerable part of the biochar volume
+consist of pores in size range relevant to hydrological processes and storage
+of plant available water. Porosity and pore-size distribution were found to
+depend on the biochar type and the structural anisotopy analysis showed that
+used raw material considerably affects the pore characteristics at micrometre
+scale. Therefore attention should be paid to raw material selection and quality
+in applications requiring optimized pore structure.",1705.08653v1
+2017-05-29,"Contributions of Co and Fe orbitals to Perpendicular Magnetic Anisotropy of MgO/CoFeB Bilayers with Spin-Orbit-Torque-Related (Ta, W, IrMn, and Ti) Underlayers","We study the perpendicular magnetic anisotropy (PMA) of the CoFeB/MgO
+bilayers in contact with W, Ta, IrMn and Ti which has been suggested as the
+spin-orbit-torque-related underlayers. The saturation magnetization of the
+CoFeB depends on the underlayer materials due to formation of a dead-layer,
+affecting PMA strength of each film. The x-ray magnetic circular dichroism
+measurement reveals that the interfacial intermixing suppresses only the
+perpendicular orbital moment of Fe, while the intermixing simultaneously
+suppresses both the perpendicular and in-plane orbital moments of Co.",1705.10064v1
+2017-05-29,Anisotropic electronic transport of the two-dimensional electron system in Al2O3/SrTiO3 heterostructures,"Transport measurements on the two dimensional electron system in Al2O3 SrTiO3
+heterostructures indicate significant noncrystalline anisotropic behavior below
+T = 30 K. Lattice dislocations in SrTiO3 and interfacial steps are suggested to
+be the main sources for electronic anisotropy. Anisotropic defect scattering
+likewise alters magnetoresistance at low temperature remarkably and influences
+spin-orbit coupling significantly by the Elliot Yafet mechanism of spin
+relaxation resulting in anisotropic weak localization. Applying a magnetic
+field parallel to the interface results in an additional field induced
+anisotropy of the conductance, which can be attributed to Rashba spin orbit
+interaction. Compared to LaAlO3 SrTiO3, Rashba coupling seems to be reduced
+indicating a weaker polarity in Al2O3 SrTiO3 heterostructures.",1705.10159v1
+2017-05-30,Heteroepitaxial growth of tetragonal Mn$_{2.7-x}$Fe$_{x}$Ga$_{1.3}$ (0 $\leqslant$ x $\leqslant$ 1.2) Heusler films with perpendicular magnetic anisotropy,"This work reports on the structural and magnetic properties of
+Mn$_{2.7-x}$Fe$_{x}$Ga$_{1.3}$ Heusler films with different Fe content x (0
+$\leqslant$ x $\leqslant$ 1.2). The films were deposited heteroepitaxially on
+MgO single crystal substrates, by magnetron sputtering.
+Mn$_{2.7-x}$Fe$_{x}$Ga$_{1.3}$ films with the thickness of 35 nm were
+crystallized in tetragonal D0$_{22}$ structure with (001) preferred
+orientation. Tunable magnetic properties were achieved by changing the Fe
+content x. Mn$_{2.7-x}$Fe$_{x}$Ga$_{1.3}$ thins films exhibit high uniaxial
+anisotropy Ku $\geqslant$ 1.4 MJ/m3, coercivity from 0.95 to 0.3 T and
+saturation magnetization from 290 to 570 kA/m. The film with
+Mn$_{1.6}$Fe$_{1.1}$Ga$_{1.3}$ composition shows high Ku of 1.47 MJ/m3 and
+energy product ${(BH)_{max}}$ of 37 kJ/m3, at room temperature. These findings
+demonstrate that Mn$_{2.7-x}$Fe$_{x}$Ga$_{1.3}$ films have promising properties
+for mid-range permanent magnet and spintronic applications.",1705.10668v1
+2017-06-02,Nonlinear anisotropic dielectric metasurfaces for ultrafast nanophotonics,"We report on the broadband transient optical response from anisotropic
+nanobrick amorphous silicon particles, exhibiting Mie-type resonances. A
+quantitative model is developed to identify and disentangle the three physical
+processes that govern the ultrafast changes of the nanobrick optical
+properties, namely two-photon absorption, free-carrier relaxation, and lattice
+heating. We reveal a set of operating windows where ultrafast all-optical
+modulation of transmission is achieved with full return to zero in 20 ps. This
+is made possible due to the interplay between the competing nonlinear processes
+and despite the slow (nanosecond) internal lattice dynamics. The observed
+ultrafast switching behavior can be independently engineered for both or-
+thogonal polarizations using the large anisotropy of nanobricks thus allowing
+ultrafast anisotropy control. Our results categorically ascertain the potential
+of all-dielectric resonant nanophotonics as a platform for ultrafast optical
+devices, and reveal the pos- sibility for ultrafast polarization-multiplexed
+displays and polarization rotators.",1706.00869v1
+2017-06-07,Zero-point spin-fluctuations of single adatoms,"Stabilizing the magnetic signal of single adatoms is a crucial step towards
+their successful usage in widespread technological applications such as
+high-density magnetic data storage devices. The quantum mechanical nature of
+these tiny objects, however, introduces intrinsic zero-point spin-fluctuations
+that tend to destabilize the local magnetic moment of interest by dwindling the
+magnetic anisotropy potential barrier even at absolute zero temperature. Here,
+we elucidate the origins and quantify the effect of the fundamental ingredients
+determining the magnitude of the fluctuations, namely the ($i$) local magnetic
+moment, ($ii$) spin-orbit coupling and ($iii$) electron-hole Stoner
+excitations. Based on a systematic first-principles study of 3d and 4d adatoms,
+we demonstrate that the transverse contribution of the fluctuations is
+comparable in size to the magnetic moment itself, leading to a remarkable
+$\gtrsim$50$\%$ reduction of the magnetic anisotropy energy. Our analysis gives
+rise to a comprehensible diagram relating the fluctuation magnitude to
+characteristic features of adatoms, providing practical guidelines for
+designing magnetically stable nanomagnets with minimal quantum fluctuations.",1706.02079v1
+2017-06-09,Optical properties of an anisotropic hot QCD medium,"The present investigation involves explorations on the chromo-dielectric
+properties of the hot QCD medium produced in relativistic heavy-ion collisions
+in terms of refractive index. The isotropic/equilibrium modelling is done
+within an effective quasi-particle model of hot QCD medium. The possibilities
+of negative refraction in the medium are also explored in terms of the
+Depine-Lakhtakia index. The anisotropic aspects of the hot QCD medium are
+incorporated by introducing the anisotropy in a particular direction. That
+makes the medium quite similar to uniaxial crystals, and hence we observe
+phenomenon of birefringence ( two distinct refractive indices in the
+anisotropic case). Interestingly, both anisotropy and medium effects play
+significant roles in deciding the optical properties of the hot
+QCD/Quark-Gluon-Plasma (QGP) medium.",1706.02995v2
+2017-06-11,A new effective-field technique for the ferromagnetic spin-1 Blume-Capel model in a transverse crystal field,"A new approximating technique is developed so as to study the quantum
+ferromagnetic spin-1 Blume-Capel model in the presence of a transverse crystal
+field in the square lattice. Our proposal consists of approaching the spin
+system by considering islands of finite clusters whose frontiers are surrounded
+by non-interacting spins that are treated by the effective-field theory. The
+resulting phase diagram is qualitatively correct, in contrast to most
+effective-field treatments, in which the first-order line exhibits spurious
+behavior by not being perpendicular to the anisotropy axis at low temperatures.
+The effect of the transverse anisotropy is also verified by the presence of
+quantum phase transitions. The possibility of using larger sizes constitutes an
+advantage to other approaches where the implementation of larger sizes is
+costly computationally.",1706.04071v1
+2017-06-16,Observation of Various and Spontaneous Magnetic Skyrmionic Bubbles at Room-Temperature in a Frustrated Kagome Magnet with Uniaxial Magnetic Anisotropy,"Various and spontaneous magnetic skyrmionic bubbles are experimentally
+observed for the first time, at room temperature in a frustrated kagome magnet
+Fe3Sn2 with unixial magnetic anisotropy. The magnetization dynamics were
+investigated using in-situ Lorentz transmission electron microscopy, revealing
+that the transformation between different magnetic bubbles and domains are via
+the motion of Bloch lines driven by applied external magnetic field. The
+results demonstrate that Fe3Sn2 facilitates a unique magnetic control of
+topological spin textures at room temperature, making it a promising candidate
+for further skyrmion-based spintronic devices.",1706.05177v1
+2017-06-16,Thermoelectric Band Engineering: The Role of Carrier Scattering,"Complex electronic band structures, with multiple valleys or bands at the
+same or similar energies can be beneficial for thermoelectric performance, but
+the advantages can be offset by inter-valley and inter-band scattering. In this
+paper, we demonstrate how first-principles band structures coupled with
+recently developed techniques for rigorous simulation of electron-phonon
+scattering provide the capabilities to realistically assess the benefits and
+trade-offs associated with these materials. We illustrate the approach using
+n-type silicon as a model material and show that intervalley scattering is
+strong. This example shows that the convergence of valleys and bands can
+improve thermoelectric performance, but the magnitude of the improvement
+depends sensitively on the relative strengths of intra- and inter-valley
+electron scattering. Because anisotropy of the band structure also plays an
+important role, a measure of the benefit of band anisotropy in the presence of
+strong intervalley scattering is presented.",1706.05241v2
+2017-06-20,Hidden peculiar magnetic anisotropy at the interface in a ferromagnetic perovskite-oxide heterostructure,"Understanding and controlling the interfacial magnetic properties of
+ferromagnetic thin films are crucial for spintronic device applications.
+However, using conventional magnetometry, it is difficult to detect them
+separately from the bulk properties. Here, by utilizing tunneling anisotropic
+magnetoresistance in a single-barrier heterostructure composed of
+La0.6Sr0.4MnO3 (LSMO)/ LaAlO3 (LAO)/ Nb-doped SrTiO3 (001), we reveal the
+presence of a peculiar strong two-fold magnetic anisotropy (MA) along the
+[110]c direction at the LSMO/LAO interface, which is not observed in bulk LSMO.
+This MA shows unknown behavior that the easy magnetization axis rotates by
+90{\deg} at an energy of 0.2 eV below the Fermi level in LSMO. We attribute
+this phenomenon to the transition between the eg and t2g bands at the LSMO
+interface. Our finding and approach to understanding the energy dependence of
+the MA demonstrate a new possibility of efficient control of the interfacial
+magnetic properties by controlling the band structures of oxide
+heterostructures.",1706.06300v1
+2017-06-24,Above 400 K Robust Perpendicular Ferromagnetic Phase in a Topological Insulator,"The quantum anomalous Hall effect (QAHE) that emerges under broken
+time-reversal symmetry in topological insulators (TI) exhibits many fascinating
+physical properties for potential applications in nano-electronics and
+spintronics. However, in transition-metal doped TI, the only experimentally
+demonstrated QAHE system to date, the effect is lost at practically relevant
+temperatures. This constraint is imposed by the relatively low Curie
+temperature (Tc) and inherent spin disorder associated with the random magnetic
+dopants. Here we demonstrate drastically enhanced Tc by exchange coupling TI to
+Tm3Fe5O12, a high-Tc magnetic insulator with perpendicular magnetic anisotropy.
+Signatures that the TI surface states acquire robust ferromagnetism are
+revealed by distinct squared anomalous Hall hysteresis loops at 400 K.
+Point-contact Andreev reflection spectroscopy confirms that the TI surface is
+indeed spin-polarized. The greatly enhanced Tc, absence of spin disorder, and
+perpendicular anisotropy are all essential to the occurrence of the QAHE at
+high temperatures.",1706.07971v1
+2017-06-24,The magnetic properties and structure of the quasi-two-dimensional antiferromagnet CoPS$_3$,"The magnetic properties and magnetic structure are presented for CoPS$_3$, a
+quasi-two-dimensional antiferromagnet on a honeycomb lattice with a N\'eel
+temperature of $T_N \sim 120$ K. The compound is shown to have XY-like
+anisotropy in its susceptibility, and the anisotropy is analysed to extract
+crystal field parameters. For temperatures between 2 K and 300 K, no phase
+transitions were observed in the field-dependent magnetization up to 10 Tesla.
+Single-crystal neutron diffraction shows that the magnetic propagation vector
+is {\bf{k}}= $\left[010\right]$ with the moments mostly along the $\mathbf{a}$
+axis and with a small component along the $\mathbf{c}$ axis, which largely
+verifies the previously-published magnetic structure for this compound. The
+magnetic Bragg peak intensity decreases with increasing temperature as a power
+law with exponent $2\beta = 0.60 \pm 0.01$ for $T > 0.9~T_N$.",1706.07989v1
+2017-06-25,The static hard-loop gluon propagator to all orders in anisotropy,"We calculate the (semi-)static hard-loop self-energy and propagator using the
+Keldysh formalism in a momentum-space anisotropic quark-gluon plasma. The
+static retarded, advanced, and Feynman (symmetric) self-energies and
+propagators are calculated to all orders in the momentum-space anisotropy
+parameter $\xi$. For the retarded and advanced self-energies/propagators, we
+present a concise derivation and comparison with previously-obtained results
+and extend the calculation of the self-energies to next-to-leading order in the
+gluon energy, $\omega$. For the Feynman self-energy/propagator, we present new
+results which are accurate to all orders in $\xi$. We compare our exact results
+with prior expressions for the Feynman self-energy/propagator which were
+obtained using Taylor-expansions around an isotropic state. We show that,
+unlike the Taylor-expanded results, the all-orders expression for the Feynman
+propagator is free from infrared singularities. Finally, we discuss the
+application of our results to the calculation of the imaginary-part of the
+heavy-quark potential in an anisotropic quark-gluon plasma.",1706.08091v1
+2017-06-26,Optically and electrically controllable adatom spin-orbital dynamics in transition metal dichalcogenides,"We analyze the interplay of spin-valley coupling, orbital physics and
+magnetic anisotropy taking place at single magnetic atoms adsorbed on
+semiconducting transition-metal dichalcogenides, MX$_2$ (M = Mo, W; X = S, Se).
+Orbital selection rules turn out to govern the kinetic exchange coupling
+between the adatom and charge carriers in the MX$_2$ and lead to highly
+orbitally dependent spin-flip scattering rates, as we illustrate for the
+example of transition metal adatoms with $d^9$ configuration. Our ab initio
+calculations suggest that $d^9$ configurations are realizable by single Co, Rh,
+or Ir adatoms on MoS$_2$, which additionally exhibit a sizable magnetic
+anisotropy. We find that the interaction of the adatom with carriers in the
+MX$_2$ allows to tune its behavior from a quantum regime with full Kondo
+screening to a regime of ""Ising spintronics"" where its spin-orbital moment acts
+as classical bit, which can be erased and written electronically and optically.",1706.08365v1
+2017-06-27,Helical and skyrmion lattice phases in three-dimensional chiral magnets: Effect of anisotropic interactions,"In this work, we study the magnetic orders of the classical spin model with
+the anisotropic exchange and Dzyaloshinskii-Moriya interactions in order to
+understand the uniaxial stress effect in chiral magnets such as MnSi.
+Variational zero temperature (T) calculated results demonstrate that various
+helical orders can be developed depending on the magnitude of the interaction
+anisotropy, consistent with the experimental observations at low T.
+Furthermore, the creation and annihilation of the skyrmions by the uniaxial
+pressure can be also qualitatively reproduced in our Monte Carlo simulations.
+Thus, our work suggests that the interaction anisotropy tuned by applied
+uniaxial stress may play an essential role in modulating the magnetic orders in
+strained chiral magnets.",1706.08677v1
+2017-06-27,Analytical and numerical $K_u - B$ phase diagrams for cobalt nanostructures: stability region for a Bloch skyrmion,"In this letter we calculate the energies corresponding to the different
+magnetic phases present in a ferromagnetic cylinder by means of analytical
+calculations. From the comparison of these energies, it is possible to
+construct magnetic phase diagrams as a function of the uniaxial anisotropy of
+the sample and the external magnetic field applied. As proof of concept, we
+analyzed the magnetic phase diagrams for a cobalt dot of 240 nm in diameter and
+70 nm in length, with an easy axis parallel to the dot axis, and with a
+magnetic field applied towards or perpendicular to this axis. From these
+diagrams we have obtained the stability regions for a Bloch skyrmion (Sk), a
+vortex core (VC) and a ferromagnetic (F) configuration, which can point in any
+$\psi$ direction. Our results provide a pathway to engineer the formation and
+controllability of a skyrmion in a ferromagnetic dot to different anisotropy
+constants and magnetic fields.",1706.08876v2
+2017-06-28,Electric control of the edge magnetization in zigzag stanene nanoribbon,"There has been tremendous interest in manipulating electron and hole-spin
+states in low-dimensional structures for electronic and spintronic
+applications. We study the edge magnetic coupling and anisotropy in zigzag
+stanene nanoribbons, by first-principles calculations. Taking into account
+considerable spin-orbit coupling and ferromagnetism at each edge, zigzag
+stanene nanoribbon is insulating and its band gap depends on the inter-edge
+magnetic coupling and the magnetization direction. Especially for nanoribbon
+edges with out-of-plane antiferromagnetic coupling, two non-degenerate valleys
+of edge states emerge and the spin degeneracy is tunable by a transverse
+electric field, which give full play to spin and valley degrees of freedom.
+More importantly, both the magnetic order and anisotropy can be selectively
+controlled by electron and hole doping, demonstrating a readily accessible
+gate-induced modulation of magnetism. These intriguing features offer a
+practical avenue for designing energy-efficient devices based on multiple
+degrees of freedom of electron and magneto-electric couplings.",1706.09098v1
+2017-06-28,Monte Carlo study of magnetic nanoparticles adsorbed on halloysite $Al_2Si_2O_5(OH)_4$ nanotubes,"We study properties of magnetic nanoparticles adsorbed on the halloysite
+surface. For that a distinct magnetic Hamiltonian with random distribution of
+spins on a cylindrical surface was solved by using a nonequilibrium Monte Carlo
+method. The parameters for our simulations: anisotropy constant, nanoparticle
+size distribution, saturated magnetization and geometrical parameters of the
+halloysite template were taken from recent experiments. We calculate the
+hysteresis loops and temperature dependence of the zero field cooling (ZFC)
+susceptibility, which maximum determines the blocking temperature. It is shown
+that the dipole-dipole interaction between nanoparticles moderately increases
+the blocking temperature and weakly increases the coercive force. The obtained
+hysteresis loops (e.g., the value of the coercive force) for Ni nanoparticles
+are in reasonable agreement with the experimental data. We also discuss the
+sensitivity of the hysteresis loops and ZFC susceptibilities to the change of
+anisotropy and dipole-dipole interaction, as well as the 3d-shell occupation of
+the metallic nanoparticles; in particular we predict larger coercive force for
+Fe, than for Ni nanoparticles.",1706.09213v2
+2017-06-30,Role of anisotropy in determining stability of electrodeposition at solid-solid interfaces,"We investigate the stability of electrodeposition at solid-solid interfaces
+for materials exhibiting an anisotropic mechanical response. The stability of
+electrodeposition or resistance to the formation of dendrites is studied within
+a linear stability analysis. The deformation and stress equations are solved
+using the Stroh formalism and faithfully recover the boundary conditions at the
+interface. The stability parameter is used to quantify the stability of
+different solid-solid interfaces incorporating the full anisotropy of the
+elastic tensor of the two materials. Results show a high degree of variability
+in the stability parameter depending on the crystallographic orientation of the
+solids in contact, and point to opportunities for exploiting this effect in
+developing Li metal anodes.",1707.00064v3
+2017-07-03,Testing the anisotropy of the Universe with the distance duality relation,"The distance duality relation (DDR) is valid in Riemannian spacetime. The
+astronomical data hint that the universe may have certain preferred direction.
+If the universe is described by anisotropic cosmological models based on
+Riemannian spacetime, then DDR still valid. If the anisotropy universe is
+described by other models which are not based on Riemannian spacetime, then DDR
+is violated. Thus, DDR could be used to test the validity of these anisotropic
+cosmological models. In this paper, we perform anisotropic DDR parametrization
+with the dipolar structures. The DDR is tested by comparing the luminosity
+distance from type-Ia supernovae (Union 2.1 and JLA compilations) and the
+angular diameter distance from strong gravitational lensing (SL) systems at the
+same redshift. It is shown that, the DDR is valid with the Union2.1
+compilation, while is violated more than 1$\sigma$ confidence level with the
+JLA compilation. Additionally, we verify the statistical signification of our
+method with Monte Carlo simulations. Due to the large uncertainty of available
+data, no strong evidence is found to violate the DDR in the anisotropic models.",1707.00390v2
+2017-06-22,"First-principles study of optical, elastic anisotropic and thermodynamic properties of TiN under high temperature and high pressure","The optical, elastic anisotropic and thermodynamic properties of TiN in the
+NaCl (B1) structure are analyzed in detail in the temperature range from 0 to
+2000 K and the pressure range from 0 to 20 GPa. From the calculated dielectric
+constants, a first order isostructural phase transition between 29 and 30 GPa
+is found for TiN. The absorption spectra exhibit high values ranging from the
+far infrared region to the ultra-violet one. The anisotropy value of Young's
+modulus of TiN is smaller than that of c-BN at 0 GPa and the anisotropy of TiN
+clearly increases with an increase of pressure. The effects of pressure and
+temperature on the bulk modulus, Gr\""uneisen parameter, Gibbs free energy, and
+Debye temperature are significant. The Gr\""uneisen parameter of TiN is much
+larger than that of c-BN. At temperatures below 1000 K, TiN's heat capacity is
+much larger than that of c-BN.",1707.00676v1
+2017-07-04,D-meson azimuthal anisotropy in mid-central Pb-Pb collisions at $\mathbf{\sqrt{s_{\rm NN}}=5.02}$ TeV,"The azimuthal anisotropy coefficient $v_2$ of prompt D$^0$, D$^+$, D$^{*+}$
+and D$_s^+$ mesons was measured in mid-central (30-50% centrality class) Pb-Pb
+collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} =
+5.02$ TeV, with the ALICE detector at the LHC. The D mesons were reconstructed
+via their hadronic decays at mid-rapidity, $|y|<0.8$, in the transverse
+momentum interval $1<p_{\rm T}<24$ GeV/$c$. The measured D-meson $v_2$ has
+similar values as that of charged pions. The D$_s^+$ $v_2$, measured for the
+first time, is found to be compatible with that of non-strange D mesons. The
+measurements are compared with theoretical calculations of charm-quark
+transport in a hydrodynamically expanding medium and have the potential to
+constrain medium parameters.",1707.01005v2
+2017-07-05,Magnetic Order in Laser-Irradiated Kagome Antiferromagnets,"Dispersionless ""zero energy mode'' is one of the hallmarks of frustrated
+kagome antiferromagnets (KAFMs). It points to extensive classically degenerate
+ground-states. The ""zero energy mode'' can be observed experimentally when
+lifted to a flat mode at finite energy by a strong intrinsic magnetic
+anisotropy. In this letter, we study the effects of irradiation of laser light
+on the KAFMs. We adopt the magnon picture without loss of generality. It is
+shown that circularly or linearly polarized light lifts the ""zero energy
+mode'', stabilizes magnetic order, and induces energy gaps in the KAFMs. We
+find that the circularly polarized light-induced anisotropies have similar
+features as the intrinsic in-plane and out-of-plane Dzyaloshinskii-Moriya
+interaction in KAFMs. The former stabilizes long-range magnetic order and the
+latter induces spin canting out-of-plane with nonzero scalar spin chirality.
+The Floquet thermal Hall effect shows that the synthetic magnetic excitation
+modes in the case of circularly polarized light are topological, whereas those
+of linearly polarized light are not.",1707.01502v3
+2017-07-06,Strong angular dependent transmission ratio due to interplay between spin waves and the domain wall in perpendicular magnetic anisotropy materials,"Spin waves (SW) can induce rich domain wall (DW) motion in a
+perpendicular-magnetic anisotropy nanostrip. In-plane magnetization tilt angle
+resulting from the fluctuation of the effective field of the magnetization
+response in the DW region plays an essential role in the dynamics of SW
+interacting with a DW. We performed simulation and found that the transmission
+ratio of the propagating SW across the DW depends strongly on the tilt angle in
+the low-frequency regime. The material parameters and the geometrical
+configuration can be fine-tuned for practical devices.",1707.01617v1
+2017-07-17,Condensate of Massive Graviton and Dark Matter,"We study coherently oscillating massive gravitons in the ghost-free bigravity
+theory. This coherent field can be interpreted as a condensate of the massive
+gravitons. We first define the effective energy-momentum tensor of the coherent
+massive gravitons in a curved spacetime. We then study the background dynamics
+of the universe and the cosmic structure formation including the effects of the
+coherent massive gravitons. We find that the condensate of the massive graviton
+behaves as a dark matter component of the universe. From the geometrical point
+of view the condensate is regarded as a spacetime anisotropy. Hence, in our
+scenario, dark matter is originated from the tiny deformation of the spacetime.
+We also discuss a production of the spacetime anisotropy and find that the
+extragalactic magnetic field of a primordial origin can yield a sufficient
+amount for dark matter.",1707.05003v2
+2017-07-18,Discrimination of anisotropy in dark matter velocity distribution with directional detectors,"Directional detection of dark matter has sensitivity for both recoil energy
+and direction of nuclear recoil. It opens the way to measure local velocity
+distribution of dark matter. In this paper, we study possibility to
+discriminate isotropic distribution and anisotropic one suggested by a N-body
+simulation with directional detector. Numerical simulation is performed for two
+cases according to the detectors, one corresponds to angular histogram and the
+other is energy-angular distribution of the signals. We reveal that the
+anisotropy of velocity distribution can be discriminated at 90% C.L. with
+chi-squared test if O($10^4$) signals are obtained.",1707.05523v3
+2017-07-25,Skyrmion mediated voltage controlled switching of ferromagnets for reliable and energy efficient 2-terminal memory,"We propose a two terminal nanomagnetic memory element based on magnetization
+reversal of a perpendicularly magnetized nanomagnet employing a unipolar
+voltage pulse that modifies the perpendicular anisotropy of the system. Our
+work demonstrates that the presence of Dzyaloshinskii-Moriya Interaction (DMI)
+can create alternative route for magnetization reversal that obviates the need
+for utilizing precessional magnetization dynamics as well as a bias magnetic
+field that are employed in traditional voltage control of magnetic anisotropy
+(VCMA) based switching of perpendicular magnetization. We show with extensive
+micromagnetic simulation, in the presence of thermal noise, that the proposed
+skyrmion mediated VCMA switching mechanism is robust at room temperature
+leading to extremely low error switching while also being potentially 1-2
+orders of magnitude more energy efficient than state of the art spin transfer
+torque (STT) based switching.",1707.07777v1
+2017-07-27,Perfect diode in quantum spin chains,"We study the rectification of spin current in $XXZ$ chains segmented in two
+parts, each with a different anisotropy parameter. Using exact diagonalization
+and a matrix product states algorithm we find that a large rectification (of
+the order of $10^4$) is attainable even using a short chain of $N=8$ spins,
+when one half of the chain is gapless while the other has large enough
+anisotropy. We present evidence of diffusive transport when the current is
+driven in one direction and of a transition to an insulating behavior of the
+system when driven in the opposite direction, leading to a perfect diode in the
+thermodynamic limit. The above results are explained in terms of matching of
+spectrum of magnon excitations between the two halves of the chain.",1707.08823v3
+2017-08-06,On the limits of coercivity in permanent magnets,"The maximum coercivity that can be achieved for a given hard magnetic alloy
+is estimated by computing the energy barrier for the nucleation of a reversed
+domain in an idealized microstructure without any structural defects and
+without any soft magnetic secondary phases. For
+Sm$_{1-z}$Zr$_z$(Fe$_{1-y}$Co$_y$)$_{12-x}$Ti$_x$ based alloys, which are
+considered an alternative to Nd$_2$Fe$_{14}$B magnets with lower rare-earth
+content, the coercive field of a small magnetic cube is reduced to 60 percent
+of the anisotropy field at room temperature and to 50 percent of the anisotropy
+field at elevated temperature (473K). This decrease of the coercive field is
+caused by misorientation, demagnetizing fields and thermal fluctuations.",1708.01880v1
+2017-08-10,Klein-Gordon field from the XXZ Heisenberg model,"We examine the recently introduced idea of Spin-Field Correspondence focusing
+on the example of the spin system described by the XXZ Heisenberg model with
+external magnetic field. The Hamiltonian of the resulting nonlinear scalar
+field theory is derived for arbitrary value of the anisotropy parameter
+$\Delta$. We show that the linear scalar field theory is reconstructed in the
+large spin limit. For $\Delta=1$ a non-relativistic scalar field theory
+satisfying the Born reciprocity principle is recovered. As expected, for the
+vanishing anisotropy parameter $\Delta \rightarrow 0$ the standard relativistic
+Klein-Gordon field is obtained. Various aspects of the obtained class of the
+scalar fields are studied, including the fate of the relativistic symmetries
+and the properties of the emerging interaction terms. We show that, in a
+certain limit, the so-called polymer quantisation of the field variables is
+recovered. This and other discussed properties suggest a possible relevance of
+the considered framework in the context of quantum gravity.",1708.03207v1
+2017-08-14,Large Proximity-Induced Spin Lifetime Anisotropy in Transition Metal Dichalcogenide/Graphene Heterostructures,"Van-der-Waals heterostructures have become a paradigm for designing new
+materials and devices, in which specific functionalities can be tailored by
+combining the properties of the individual 2D layers. A single layer of
+transition metal dichalcogenide (TMD) is an excellent complement to graphene
+(Gr), since the high quality of charge and spin transport in Gr is enriched
+with the large spin-orbit coupling of the TMD via proximity effect. The
+controllable spin-valley coupling makes these heterostructures particularly
+attractive for spintronic and opto-valleytronic applications. In this work, we
+study spin precession in a monolayer MoSe2/Gr heterostructure and observe an
+unconventional, dramatic modulation of the spin signal, showing one order of
+magnitude longer lifetime of out-of-plane spins (40 ps) compared with that of
+in-plane spins (3.5 ps). This demonstration of a large spin lifetime anisotropy
+in TMD/Gr heterostructures, is a direct evidence of induced spin-valley
+coupling in Gr and provides an accessible route for manipulation of spin
+dynamics in Gr, interfaced with TMDs.",1708.04067v1
+2017-08-14,Robustness of the semimetal state of Na3Bi and Cd3As2 against Coulomb interaction,"We study the excitonic semimetal-insulator quantum phase transition in
+three-dimensional Dirac semimetal in which the fermion dispersion is strongly
+anisotropic. After solving the Dyson-Schwinger equation for the excitonic gap,
+we obtain a global phase diagram in the plane spanned by the parameter for
+Coulomb interaction strength and the parameter for fermion velocity anisotropy.
+We find that excitonic gap generation is promoted as the interaction becomes
+stronger, but is suppressed if the anisotropy increases. Applying our results
+to two realistic three-dimensional Dirac semimetals Na$_{3}$Bi and
+Cd$_{3}$As$_{2}$, we establish that their exact zero-temperature ground state
+is gapless semimetal, rather than excitonic insulator. Moreover, these two
+materials are far from the excitonic quantum critical point, thus there should
+not be any observable evidence for excitonic insulating behavior. This
+conclusion is in general agreement with the existing experiments of Na$_{3}$Bi
+and Cd$_{3}$As$_{2}$.",1708.04080v2
+2017-08-15,Laser-written polarizing directional coupler with reduced interaction length,"Integrated optical devices are becoming a common tool in modern optical
+science and engineering. This devices should be designed to allow for precise
+control and manipulation of light. The femtosecond laser written (FSLW)
+photonic chips have proven to cope with the most current demands of integrated
+photonics. However, up to date the polarization degree of freedom has rarely
+been exploited in experiments performed on the FSLW integrated platform. The
+main obstacle is an intrinsically low anisotropy of laser written waveguides,
+preventing the design of polarizing integrated devices with small footprint. In
+this Letter we demonstrate the approach based on stress-induced anisotropy
+allowing us to decrease the size of polarizing directional couplers fabricated
+with the FSLW technology by almost an order of magnitude. We provide an
+accurate account for the effects emerging in waveguides written in a close
+proximity to each over.",1708.04450v1
+2017-08-24,Delocalizing Entanglement of Anisotropic Black Branes,"We study the mutual information between pairs of regions on the two
+asymptotic boundaries of maximally-extended anisotropic black-brane solutions.
+This quantity characterizes the local pattern of entanglement of thermofield
+double states which are dual to these geometries. We analyse the disruption of
+the mutual information in anisotropic shock wave geometries and show that the
+entanglement velocity plays an important role in this phenomenon. Besides that
+we compute several chaos-related properties of this system, like the
+entanglement velocity, the butterfly velocity and the scrambling time. We find
+that the butterfly velocity and the entanglement velocity violate the upper
+bounds proposed in 1311.1200 and 1612.00082, but remain bounded by their
+corresponding values in the infrared effective theory.",1708.07243v3
+2017-08-24,MgO thickness-induced spin reorientation transition in Co0.9Fe0.1/MgO/Co0.9Fe0.1 structure,"The magnetic anisotropy (MA) of Mo/Au/Co0.9Fe0.1/Au/MgO(0.7 - 3
+nm)/Au/Co0.9Fe0.1/Au heterostructure has been investigated at room temperature
+as a function of MgO layer thickness (tMgO). Our studies show that while the MA
+of the top layer does not change its character upon variation of tMgO, the
+uniaxial out-of-plane MA of the bottom one undergoes a spin reorientation
+transition at tMgO of about 0.8 nm, switching to the regime where the
+coexistence of in- and out-of-plane magnetization alignments is observed. The
+magnitudes of the magnetic anisotropy constants have been determined from
+ferromagnetic resonance and dc-magnetometry measurements. The origin of MA
+evolution has been attributed to a presence of an interlayer exchange coupling
+(IEC) between Co0.9Fe0.1 layers through the thin MgO film.",1708.07382v1
+2017-08-29,Spin Dynamics in a Stripe-ordered Buckled Honeycomb Lattice Antiferromagnet Ba$_{2}$NiTeO$_{6}$,"We carried out inelastic neutron scattering experiments on a buckled
+honeycomb lattice antiferromagnet Ba$_{2}$NiTeO$_{6}$ exhibiting a stripe
+structure at a low temperature. Magnetic excitations are observed in the energy
+range of $\hbar \omega \lesssim 10$ meV having an anisotropy gap of 2 meV at 2
+K. We perform spin-wave calculations to identify the spin model. The obtained
+microscopic parameters are consistent with the location of the stripe structure
+in the classical phase diagram. Furthermore, the Weiss temperature
+independently estimated from a bulk magnetic susceptibility is consistent with
+the microscopic parameters. The results reveal that a competition between the
+NN and NNN interactions that together with a relatively large single ion
+magnetic anisotropy stabilize the stripe magnetic structure.",1708.08717v1
+2017-09-03,Dynamics of the vortex line density in superfluid counterflow turbulence,"Describing superfluid turbulence at intermediate scales between the
+inter-vortex distance and the macroscale requires an acceptable equation of
+motion for the density of quantized vortex lines $\cal{L}$. The closure of such
+an equation for superfluid inhomogeneous flows requires additional inputs
+besides $\cal{L}$ and the normal and superfluid velocity fields. In this paper
+we offer a minimal closure using one additional anisotropy parameter $I_{l0}$.
+Using the example of counterflow superfluid turbulence we derive two coupled
+closure equations for the vortex line density and the anisotropy parameter
+$I_{l0}$ with an input of the normal and superfluid velocity fields. The
+various closure assumptions and the predictions of the resulting theory are
+tested against numerical simulations.",1709.00671v2
+2017-09-04,Plum pudding random medium model of biological tissue toward remote microscopy from spectroscopic light scattering,"Biological tissue has a complex structure and exhibits rich spectroscopic
+behavior. There is \emph{no} tissue model up to now able to account for the
+observed spectroscopy of tissue light scattering and its anisotropy. Here we
+present, \emph{for the first time}, a plum pudding random medium (PPRM) model
+for biological tissue which succinctly describes tissue as a superposition of
+distinctive scattering structures (plum) embedded inside a fractal continuous
+medium of background refractive index fluctuation (pudding). PPRM faithfully
+reproduces the wavelength dependence of tissue light scattering and attributes
+the ""anomalous"" trend in the anisotropy to the plum and the powerlaw dependence
+of the reduced scattering coefficient to the fractal scattering pudding. Most
+importantly, PPRM opens up a novel venue of quantifying the tissue architecture
+and microscopic structures on average from macroscopic probing of the bulk with
+scattered light alone without tissue excision. We demonstrate this potential by
+visualizing the fine microscopic structural alterations in breast tissue
+(adipose, glandular, fibrocystic, fibroadenoma, and ductal carcinoma) deduced
+from noncontact spectroscopic measurement.",1709.00795v1
+2017-09-05,"Pinning, Rotation, and Metastability of BiFeO$_3$ Cycloidal Domains in a Magnetic Field","Earlier models for the room-temperature multiferroic BiFeO3 implicitly
+assumed that a very strong anisotropy restricts the domain wavevectors q to the
+three-fold symmetric axis normal to the static polarization P. However, recent
+measurements demonstrate that the domain wavevectors rotate so that q rotates
+within the hexagonal plane normal to P away from the field orientation m. We
+show that the previously neglected three-fold anisotropy K3 restricts the
+wavevectors to lie along the three-fold axis in zero field. For m along a
+three-fold axis, the domain with q parallel to m remains metastable below Bc1 =
+7 T. Due to the pinning of domains by non-magnetic impurities, the wavevectors
+of the other two domains start to rotate away from m above 5.6 T, when the
+component of the torque t = M x B along P exceeds a threshold value tpin. Since
+t =0 when m is perpendicular to q, the wavevectors of those domains never
+become completely perpendicular to the magnetic field. Our results explain
+recent measurements of the critical field as a function of field orientation,
+small-angle neutron scattering measurements of the wavevectors, as well as
+spectroscopic measurements with m along a three-fold axis.",1709.01428v2
+2017-09-12,Controllable transport of a skyrmion in a ferromagnetic narrow channel with voltage-controlled magnetic anisotropy,"Magnetic skyrmions have potential applications in next-generation spintronics
+devices with ultralow energy consumption. In this work, the current-driven
+skyrmion motion in a narrow ferromagnetic nanotrack with voltage-controlled
+magnetic anisotropy (VCMA) is studied numerically. By utilizing the VCMA
+effect, the transport of skyrmion can be unidirectional in the nanotrack,
+leading to a one-way information channel. The trajectory of the skyrmion can
+also be modulated by periodically located VCMA gates, which protects the
+skyrmion from destruction by touching the track edge. In addition, the location
+of the skyrmion can be controlled by adjusting the driving pulse length in the
+presence of the VCMA effect. Our results provide guidelines for practical
+realization of the skyrmion-based information channel, diode, and racetrack
+memory.",1709.03733v1
+2017-09-17,Detecting higher spin fields through statistical anisotropy in the CMB and galaxy power spectra,"Primordial inflation may represent the most powerful collider to test
+high-energy physics models. In this paper we study the impact on the
+inflationary power spectrum of the comoving curvature perturbation in the
+specific model where massive higher spin fields are rendered effectively
+massless during a de Sitter epoch through suitable couplings to the inflaton
+field. In particular, we show that such fields with spin $s$ induce a
+distinctive statistical anisotropic signal on the power spectrum, in such a way
+that not only the usual $g_{2M}$-statistical anisotropy coefficients, but also
+higher-order ones (i.e., $g_{4M}$, $g_{6M}$, $\cdots$, $g_{(2s-2)M}$ and
+$g_{(2s) M}$) are nonvanishing. We examine their imprints in the cosmic
+microwave background and galaxy power spectra. Our Fisher matrix forecasts
+indicate that the detectability of $g_{LM}$ depends very weakly on $L$: all
+coefficients could be detected in near future if their magnitudes are bigger
+than about $10^{-3}$.",1709.05695v2
+2017-09-21,Anisotropy effects on Baryogenesis in $f(R)$-Theories of Gravity,"We study the $f(R)$ theory of gravity in an anisotropic metric and its effect
+on the baryon number to entropy ratio. The mechanism of gravitational
+baryogenesis based on the CPT-violating gravitational interaction between
+derivative of the Ricci scalar curvature and the baryon-number current is
+investigated in the context of the $f(R)$ gravity. The gravitational
+baryogenesis in the Bianchi type I universe is examined. We survey the effect
+of anisotropy of the universe on the baryon asymmetry from point of view the
+$f(R)$-theories of gravity and its effect on $n_{b}/s$ for radiation dominant
+regime.",1709.06996v3
+2017-09-26,Observation of correlated azimuthal anisotropy Fourier harmonics in pp and pPb collisions at the LHC,"The azimuthal anisotropy Fourier coefficients ($v_n$) in 8.16 TeV pPb data
+are extracted via long-range two-particle correlations as a function of event
+multiplicity and compared to corresponding results in pp and PbPb collisions.
+Using a four-particle cumulant technique, $v_n$ correlations are measured for
+the first time in pp and pPb collisions. The $v_2$ and $v_4$ coefficients are
+found to be positively correlated in all collision systems. For high
+multiplicity pPb collisions an anticorrelation of $v_2$ and $v_3$ is observed,
+with a similar correlation strength as in PbPb data at the same multiplicity.
+The new correlation results strengthen the case for a common origin of the
+collectivity seen in pPb and PbPb collisions in the measured multiplicity
+range.",1709.09189v2
+2017-09-27,The influence of superparamagnetism on exchange anisotropy at CoO/[Co/Pd] interfaces,"Magnetic systems exhibiting exchange bias effect are being considered as
+materials for applications in data storage devices, sensors and biomedicine. As
+the size of new mag- netic devices is being continuously reduced, the influence
+of thermally induced instabilities in magnetic order has to be taken into
+account during their fabrication process. In this study we show the influence
+of superparamagnetism on magnetic properties of exchange-biased [CoO/Co/Pd]10
+multilayer. We find that the process of progressive thermal blocking of the
+superparamagnetic clusters causes an unusually fast rise of the exchange
+anisotropy field and coercivity, and promotes the easy axis switching to
+out-of-plane direction.",1709.09399v1
+2017-09-27,Anisotropic Particles Strengthen Granular Pillars under Compression,"We probe the effects of particle shape on the global and local behavior of a
+two-dimensional granular pillar, acting as a proxy for a disordered solid,
+under uniaxial compression. This geometry allows for direct measurement of
+global material response, as well as tracking of all individual particle
+trajectories. In general, drawing connections between local structure and local
+dynamics can be challenging in amorphous materials due to lower precision of
+atomic positions, so this study aims to elucidate such connections. We vary
+local interactions by using three different particle shapes: discrete circular
+grains (monomers), pairs of grains bonded together (dimers), and groups of
+three bonded in a triangle (trimers). We find that dimers substantially
+strengthen the pillar and the degree of this effect is determined by
+orientational order in the initial condition. In addition, while the three
+particle shapes form void regions at distinct rates, we find that anisotropies
+in the local amorphous structure remain robust through the definition of a
+metric that quantifies packing anisotropy. Finally, we highlight connections
+between local deformation rates and local structure.",1709.09511v2
+2017-09-28,Tailoring the exchange bias effect by in-plane magnetic anisotropy,"We report an unusual, non-monotonous dependence of the exchange bias on the
+thickness of the ferromagnetic layer in a ferromagnet/antiferromagnet bilayer
+system. We show that in epitaxial CoO/Fe(110) bilayers, the evolution of the Fe
+magnetic anisotropy, which drives the thickness-induced in-plane
+spin-reorientation process, controls the interfacial CoO spin directions in the
+0-90 degrees range and, consequently, drastically modifies the magnitude of the
+hysteresis loop shift and its dependence on the thickness of the Fe layer. Our
+results present a new recipe for tailoring the exchange bias and
+antiferromagnetic spin structure by utilizing the spin-reorientation process
+that occurs in a ferromagnetic layer adjacent to an antiferromagnetic layer.",1709.09925v1
+2017-09-20,Tailoring Magnetic Skyrmions by Geometric Confinement of Magnetic Structures,"Nanoscale magnetic skyrmions have interesting static and transport properties
+that make them candidates for future spintronic devices. Control and
+manipulation of the size and behavior of skyrmions is thus of crucial
+importance. Using a Ginzburg-Landau approach, we show theoretically that
+skyrmions and skyrmion lattices can be stabilized by a spatial modulation of
+the uniaxial magnetic anisotropy in a thin film of centro-symmetric
+ferromagnet. Remarkably, the skyrmion size is determined by the ratio of the
+exchange length and the period of the spatial modulation of the anisotropy, at
+variance with conventional skyrmions stabilized by dipolar and
+Dzyaloshinskii--Moriya interactions (DMIs).",1710.00048v1
+2017-10-03,Brownian Motion and Entropic Torque Driven Motion of Domain-Wall in Antiferromagnets,"We study the spin dynamics in antiferromagnetic nanowire under an applied
+temperature gradient using micromagnetic simulations on a classical spin model
+with a uniaxial anisotropy. The entropic torque driven domain-wall motion and
+the Brownian motion are discussed in detail, and their competition determines
+the antiferromagnetic wall motion towards the hotter or colder region.
+Furthermore, the spin dynamics in an antiferromagnet can be well tuned by the
+anisotropy and the temperature gradient. Thus, this paper not only strengthens
+the main conclusions obtained in earlier works [Kim et al., Phys. Rev. B 92,
+020402(R) (2015); Selzer et al., Phys. Rev. Lett. 117, 107201 (2016)], but more
+importantly gives the concrete conditions under which these conclusions apply,
+respectively. Our results may provide useful information on the
+antiferromagnetic spintronics for future experiments and storage device design.",1710.01196v2
+2017-10-09,Weak magnetic anisotropy in GdRh$_2$Si$_2$ studied by magnetic resonance,"The antiferromagnetically (AFM) ordered state of GdRh$_{2}$Si$_{2}$ which
+consists of AFM-stacked ferromagnetic layers is investigated by magnetic
+resonance spectroscopy. The almost isotropic Gd$^{3+}$ paramagnetic resonance
+becomes anisotropic in the AFM ordered region below 107 K. The emerging
+internal anisotropic exchange-fields are still small enough to allow an
+investigation of their magnetization dynamics by using a standard
+microwave-frequency magnetic resonance technique. We could characterize this
+anisotropy in detail in the ferromagnetic layers of the excitation at 9 and 34
+GHz. We derived a resonance condition for the AFM ordered phase to describe the
+weak in-plane anisotropic behaviour in combination with a mean-field analysis.",1710.03079v1
+2017-10-09,Confinement study of an SU(4) gauge theory with fermions in multiple representations,"We discuss the phase diagnostics used in our finite-temperature study of an
+SU(4) gauge theory with dynamical fermions in both the fundamental and
+two-index antisymmetric representations. Beyond the usual Polyakov loop
+diagnostics of confinement, we employ several Wilson flow phase diagnostics.
+The first, what we call the ""flow anisotropy"", is known in the literature: the
+deconfinement transition introduces anisotropy between the spatial and temporal
+directions, to which the flow is extremely sensitive. The second, the ""long
+flow time Polyakov loop,"" is related but novel. While we do not claim to fully
+understand this diagnostic, we have empirically found it to be useful as an
+unusually sharp diagnostic of phase.",1710.03257v1
+2017-10-10,Fully Kinetic Simulation of 3D Kinetic Alfven Turbulence,"We present results from a three-dimensional particle-in-cell simulation of
+plasma turbulence, resembling the plasma conditions found at kinetic scales of
+the solar wind. The spectral properties of the turbulence in the subion range
+are consistent with theoretical expectations for kinetic Alfv\' en waves.
+Furthermore, we calculate the local anisotropy, defined by the relation
+$k_{\parallel}(k_{\perp})$, where $k_{\parallel}$ is a characteristic wave
+number along the local mean magnetic field at perpendicular scale
+$l_{\perp}\sim 1/k_{\perp}$. The subion range anisotropy is scale dependent
+with $k_{\parallel}<k_{\perp}$ and the ratio of linear to nonlinear time scales
+is of order unity, suggesting that the kinetic cascade is close to a state of
+critical balance. Our results compare favorably against a number of \emph{in
+situ} solar wind observations and demonstrate---from first principles---the
+feasibility of plasma turbulence models based on a critically balanced cascade
+of kinetic Alfv\' en waves.",1710.03581v2
+2017-10-18,Cluster-glass phase in pyrochlore XY antiferromagnets with quenched disorder,"We study the impact of quenched disorder (random exchange couplings or site
+dilution) on easy-plane pyrochlore antiferromagnets. In the clean system,
+order-by-disorder selects a magnetically ordered state from a classically
+degenerate manifold. In the presence of randomness, however, different orders
+can be chosen locally depending on details of the disorder configuration. Using
+a combination of analytical considerations and classical Monte-Carlo
+simulations, we argue that any long-range-ordered magnetic state is destroyed
+beyond a critical level of randomness where the system breaks into magnetic
+domains due to random exchange anisotropies, becoming, therefore, a glass of
+spin clusters, in accordance with the available experimental data. These random
+anisotropies originate from off-diagonal exchange couplings in the microscopic
+Hamiltonian, establishing their relevance to other magnets with strong
+spin-orbit coupling.",1710.06658v2
+2017-10-23,Manipulating Magnetic Moments by Superconducting Currents,"We show that the interaction between a superconducting order parameter and
+the magnetic moment of an atomic cluster in a two-dimensional s-wave
+superconductor with Rashba spin-orbit coupling generates magnetic anisotropy
+that can be stronger or comparable to the magnetic anisotropy due to the
+crystal field and the shape of the cluster. Transport current through the
+superconductor produces the effective magnetic field acting on the cluster's
+magnetic moment. The direction of the effective field depends on the direction
+of the current, thus allowing one to manipulate the magnetic moment by the
+superconducting current. Due to the large density of the superconducting
+current this method of magnetization reversal can be more advantageous at low
+temperatures than the spin-transfer torque method that requires a large
+spin-polarized current through a normal metal.",1710.08157v1
+2017-10-23,Magnetic anisotropy in antiferromagnetic hexagonal MnTe,"Antiferromagnetic hexagonal MnTe is a promising material for spintronic
+devices relying on the control of antiferromagnetic domain orientations. Here
+we report on neutron diffraction, magnetotransport, and magnetometry
+experiments on semiconducting epitaxial MnTe thin films together with density
+functional theory (DFT) calculations of the magnetic anisotropies.
+  The easy axes of the magnetic moments within the hexagonal basal plane are
+determined to be along $\left<1\bar100\right>$ directions. The spin-flop
+transition and concomitant repopulation of domains in strong magnetic fields is
+observed.
+  Using epitaxially induced strain the onset of the spin-flop transition
+changes from $\sim2$~T to $\sim0.5$~T for films grown on InP and SrF$_2$
+substrates, respectively.",1710.08523v2
+2017-10-25,Highlights from the Pierre Auger Observatory (ICRC17),"In this contribution we summarize the highlights from the Pierre Auger
+Observatory presented at the 35th International Cosmic Ray Conference. We
+discuss the update of the measurement of the energy spectrum of cosmic rays
+over a wide range of energy ($10^{17.5}$ to above $10^{20}$ eV), studies of the
+cosmic-ray mass composition with the fluorescence and surface detector of the
+Observatory, the discovery of a large-scale anisotropy in the arrival direction
+of cosmic rays above $8\times 10^{18}$ eV and indications of anisotropy at
+intermediate angular scales above $4 \times 10^{19}$ eV. Moreover, we report on
+tests of hadronic interactions beyond LHC energies, multi-messenger analyses
+with neutral primaries and the progress of the upgrade of the Observatory,
+AugerPrime, aimed at elucidating the origin of the observed flux suppression at
+ultra-high energies.",1710.09478v1
+2017-10-26,Dynamical spin accumulation in large-spin magnetic molecules,"The frequency-dependent transport through a nano-device containing a
+large-spin magnetic molecule is studied theoretically in the Kondo regime.
+Specifically, the effect of magnetic anisotropy on dynamical spin accumulation
+is of primary interest. Such accumulation arises due to finite off-diagonal in
+spin components of the dynamical conductance. Here, employing the Kubo
+formalism and the numerical renormalization group (NRG) method, we demonstrate
+that the dynamical transport properties strongly depend on magnetic
+configuration of the device and intrinsic parameters of the molecule.
+Specifically, the effect of dynamical spin accumulation is found to be greatly
+affected by the type of magnetic anisotropy exhibited by the molecule, and it
+develops for frequencies corresponding to the Kondo temperature. For the
+parallel magnetic configuration of the device, the presence of dynamical spin
+accumulation is conditioned by the interplay of ferromagnetic-lead-induced
+exchange field and the Kondo correlations.",1710.09623v1
+2017-10-27,Electron effective mass in Sn-doped monoclinic single crystal $β$-gallium oxide determined by mid-infrared optical Hall effect,"The isotropic average conduction band minimum electron effective mass in
+Sn-doped monoclinic single crystal $\beta$-Ga$_2$O$_3$ is experimentally
+determined by mid-infrared optical Hall effect to be $(0.284\pm0.013)m_{0}$
+combining investigations on ($010$) and ($\bar{2}01$) surface cuts. This result
+falls within the broad range of values predicted by theoretical calculations
+for undoped $\beta$-Ga$_2$O$_3$. The result is also comparable to recent
+density functional calculations using the
+Gaussian-attenuation-Perdue-Burke-Ernzerhof hybrid density functional, which
+predict an average effective mass of $0.267m_{0}$ (arXiv:1704.06711
+[cond-mat.mtrl-sci]). Within our uncertainty limits we detect no anisotropy for
+the electron effective mass, which is consistent with most previous theoretical
+calculations. We discuss upper limits for possible anisotropy of the electron
+effective mass parameter from our experimental uncertainty limits, and we
+compare our findings with recent theoretical results.",1710.10094v1
+2017-10-27,Evidence of thermal transport anisotropy in stable glasses of vapour deposited organic molecules,"Vapour-deposited organic glasses are currently in use in many optoelectronic
+devices. Their operation temperature is limited by the glass transition
+temperature of the organic layers and thermal management strategies become
+increasingly important to improve the lifetime of the device. Here we report
+the unusual finding that molecular orientation heavily influences heat flow
+propagation in glassy films of small molecule organic semiconductors. The
+thermal conductivity of vapour-deposited thin-film semiconductor glasses is
+anisotropic and controlled by the deposition temperature. We compare our data
+with extensive molecular dynamics simulations to disentangle the role of
+density and molecular orientation on heat propagation. Simulations do support
+the view that thermal transport along the backbone of the organic molecule is
+strongly preferred with respect to the perpendicular direction. This is due to
+the anisotropy of the molecular interaction strength that limit the transport
+of atomic vibrations. This approach could be used in future developments to
+implement small molecule glassy films in thermoelectric or other organic
+electronic devices.",1710.10123v1
+2017-10-29,Writing and storing information in an array of magnetic vortex nanodisks using their azimuthal modes,"The switching of a vortex core of a single disk in an array of a multilayer
+system is investigated by micromagnetic simulation. We found that the
+perpendicular uniaxial anisotropy (PUA) decreases the frequencies of the
+azimuthal mode in disks with magnetic vortex configuration. We obtained a phase
+diagram of magnetic field intensity vs. frequency of the azimuthal mode, as a
+function of the value of perpendicular uniaxial anisotropy. We demonstrated
+that rotating magnetic fields (CW and CCW) with frequency equal to azimuthal
+modes can be used to switch the vortex core of single disks in a disk array.
+This allows obtaining different memory states with a single array of nanodisks,
+and therefore writing information through the application of rotating fields.",1710.10613v1
+2017-10-31,Kink confinement in the antiferromagnetic XXZ spin-1/2 chain in a weak staggered magnetic field,"The Heisenberg XXZ spin-1/2 chain is considered in the massive
+antiferromagnetic regime in the presence of a staggered longitudinal magnetic
+field. The Hamiltonian of the model is characterised by the anisotropy
+parameter $\Delta<-1$, and by the magnetic field strength h. At zero magnetic
+field, the model is exactly solvable. In the thermodynamic limit, it has two
+degenerate vacua and the kinks (which are also called spinons) interpolating
+between these vacua, as elementary excitations. Application of the staggered
+magnetic field breaks integrability of the model and induces the long-range
+attractive potential between two adjacent kinks leading to their confinement
+into the bound states. The energy spectra of the resulting two-kink bound
+states are perturbatively calculated in the extreme anisotropic (Ising) limit
+$\Delta\to-\infty$ to the first order in the inverse anisotropy constant
+$|\Delta|^{-1}$, and also for generic values of $\Delta<-1$ to the first order
+in the weak magnetic field h.",1710.11605v2
+2017-11-06,Impact of domain anisotropy on the inverse cascade in geostrophic turbulent convection,"The effect of domain anisotropy on the inverse cascade occurring within the
+geostrophic turbulence regime of rapidly rotating Rayleigh-B\'enard convection
+(RRBC) is investigated. In periodic domains with square cross-section in the
+horizontal a domain-filling dipole state is present. For rectangular periodic
+domains a Kolmogorov-like flow consisting of a periodic array of alternating
+unidirectional jets with embedded vortices is observed, together with an
+underlying weak meandering transverse jet. Similar transitions occurring in
+weakly dissipative two-dimensional flows driven by externally imposed small
+amplitude noise as well as in classical hydrostatic geostrophic turbulence are
+a consequence of inviscid conservation of energy and potential enstrophy and
+can be understood using statistical mechanics considerations. RRBC represents
+an important three-dimensional system with only one inviscid invariant that
+nonetheless exhibits large-scale structures driven by intrinsically generated
+fluctuations.",1711.01685v1
+2017-11-07,Study on Effects of Dipole-dipole Interactions in Nd_2Fe_{14}B thin film Based on Stochastic Cut-off Method with New Efficient Algorithm,"We developed a new algorithm for the stochastic cutoff method, which is a
+Monte Carlo method for long-range interacting systems. The present new
+algorithm is efficient for complicated lattice structures, e.g., amorphous and
+also materials with complicated unit cell structure. In addition, it has an
+advantage in a high temperature region. With the present method, we
+investigated an atomistic model of the permanent magnet Nd 2 Fe 14 B with
+dipole-dipole interactions to study the effect of the anisotropy of the Fe ions
+on the magnetization structure in the thin film system. It has revealed that
+the anisotropy of the Fe ions plays an important role to maintain the uniaxial
+magnetization structure at high temperatures.",1711.02284v2
+2017-11-16,Testing the isotropy of the Universe with type Ia supernovae in a model-independent way,"In this paper, we study an anisotropic universe model with Bianchi-I metric
+using Joint Light-curve Analysis (JLA) sample of type Ia supernovae (SNe Ia).
+Because light-curve parameters of SNe Ia vary with different cosmological
+models and SNe Ia samples, we fit the SNe Ia light-curve parameters and
+cosmological parameters simultaneously employing Markov Chain Monte Carlo
+method. Therefore, the results on the amount of deviation from isotropy of the
+dark energy equation of state ($\delta$), and the level of anisotropy of the
+large-scale geometry ($\Sigma_0$) at present, are totally model-independent.
+The constraints on the skewness and cosmic shear are $-0.101<\delta<0.071$ and
+$-0.007<\Sigma_0<0.008$. This result is consistent with a standard isotropic
+universe ($\delta=\Sigma_0=0$). However, a moderate level of anisotropy in the
+geometry of the Universe and the equation of state of dark energy, is allowed.
+Besides, there is no obvious evidence for a preferred direction of anisotropic
+axis in this model.",1711.05974v1
+2017-11-19,Room-temperature observation and current control of skyrmions in Pt/Co/Os/Pt thin films,"We report the observation of room-temperature magnetic skyrmions in
+Pt/Co/Os/Pt thin-film heterostructures and their response to electric currents.
+The magnetic properties are extremely sensitive to inserting thin Os layers
+between the Co-Pt interface resulting in reduced saturation magnetization,
+magnetic anisotropy and Curie temperature. The observed skyrmions exist in a
+narrow temperature, applied-field and layer-thickness range near the
+spin-reorientation transition from perpendicular to in-plane magnetic
+anisotropy. The skyrmions have an average diameter of 2.3{\mu}m and transport
+measurements demonstrate these features can be displaced with current densities
+as low as J = 2x10^4 A/cm^2 and display a skyrmion Hall effect.",1711.07101v1
+2017-11-24,Heavy Quarks in Strongly Coupled Non-Conformal Plasmas with Anisotropy,"We analysis physical observables of heavy quarks in gravity models describing
+strongly coupled non-conformal plasmas with anisotropy via the gauge/gravity
+duality. The focus lies on the binding energy of static quark-antiquark $(q\bar
+q$-)pairs, the maximum distance (screening distance) of a bound $q\bar q$-pair
+and the drag force on uniformly moving quarks in the hot plasma. In order to
+discover universal behavior in the observables, the computations are worked out
+in a two parameter deformation of pure gravity in $AdS_5$ spacetime with a
+black brane which is assumed to be dual to a respective two parameter
+deformation of $\mathcal{N}$=\,4 supersymmetric Yang-Mills (SYM) theory at
+temperature $T$. The deformation is designed to break isotropy and conformal
+symmetry and is a solution to equations of motion of a gravity action.",1711.08943v2
+2017-11-30,Domain Wall Motion Driven by Laplace Pressure in CoFeB-MgO Nanodots with Perpendicular Anisotropy,"We have studied the magnetization reversal of CoFeB-MgO nanodots with
+perpendicular anisotropy for size ranging from w=400 nm to 1 {\mu}m. Contrary
+to previous experiments, the switching field distribution is shifted toward
+lower magnetic fields as the size of the elements is reduced with a mean
+switching field varying as 1/w. We show that this mechanism can be explained by
+the nucleation of a pinned magnetic domain wall (DW) at the edges of the
+nanodots where damages are introduced by the patterning process. As the surface
+tension (Laplace pressure) applied on the DW increases when reducing the size
+of the nanodots, we demonstrate that the depinning field to reverse the entire
+elements varies as 1/w. These results suggest that the presence of DWs has to
+be considered in the switching process of nanoscale elements and open a path
+toward scalable spintronic devices.",1711.11334v2
+2017-12-01,Active control of thermomagnetic avalanches in superconducting Nb films with tunable anisotropy,"Active triggering and manipulation of ultrafast flux dynamics in
+superconductors are demonstrated in films of Nb. Controlled amounts of magnetic
+flux were injected from a point along the edge of a square sample, which at 2.5
+K responds by nucleation of a thermomagnetic avalanche. Magneto-optical imaging
+was used to show that when such films are cooled in the presence of in-plane
+magnetic fields they become anisotropic, and the morphology of the avalanches
+change systematically, both with the direction and magnitude of the field. The
+images reveal that the avalanching dendrites consistently bend towards the
+direction perpendicular to that of the in-plane field. The effect increases
+with the field magnitude, and at 1.5 kOe the triggered avalanche becomes
+quenched at the nucleation stage. The experimental results are explained based
+on a theoretical model for thermomagnetic avalanche nucleation in
+superconducting films, and by assuming that the frozen-in flux generates
+in-plane anisotropy in the film thermal conductance. The results demonstrate
+that applying in-plane magnetic fields to film superconductors can be a
+versatile external tool for controlling their ultrafast flux dynamics.",1712.00300v1
+2017-12-04,Directed Self-Assembly of Polarizable Ellipsoids in an External Electric Field,"The interplay between shape anisotropy and directed long-range interactions
+enables the self-assembly of complex colloidal structures. As a recent
+highlight, ellipsoidal particles polarized in an external electric field were
+observed to associate into well-defined tubular structures. In this study, we
+investigate systematically such directed self-assembly using Monte Carlo
+simulations of a two-point-charge model of polarizable prolate ellipsoids. In
+spite of its simplicity and computational efficiency, we demonstrate that the
+model is capable of capturing the complex structures observed in experiments on
+ellipsoidal colloids at low volume fractions. We show that, at sufficiently
+high electric field strength, the anisotropy in shape and electrostatic
+interactions causes a transition from 3-dimensional crystal structures observed
+at low aspect ratios to 2-dimensional sheets and tubes at higher aspect ratios.
+Our work thus illustrates the rich self-assembly behavior accessible when
+exploiting the interplay between competing long- and short-range anisotropic
+interactions in colloidal systems.",1712.01025v1
+2017-10-14,Magnetocaloric Effect and Magnetic refrigeration: analytic and numeric study,"This work aims to present an analytical and numerical study of the
+magnetocaloric effects (MCE) providing realistic proposals about materials that
+should be chosen in the design of new refrigerator appliances around the room
+temperature. Starting from a spin Hamiltonian including the exchange
+interaction, the single-ion anisotropy and the applied magnetic field terms, we
+have calculated the partition function at a given temperature and derived a set
+of relevant physical quantities as magnetization, magnetic entropy and specific
+heat and analyzed their behavior with atomic parameters as spin, exchange and
+anisotropy. Using numerical programs that we developed by ourselves, we were
+able to better elucidate the role of each microscopic parameter in order to
+reinforce the relative cooling power (RCP) and give rise to optimal
+performances of the refrigerant compound. This approach could be extended to
+composite materials underscoring a giant MCE at room temperature.
+  Key-words Magnetic refrigeration, Magnetocaloric Effect, Energy efficiency,
+Spin Hamiltonian",1712.01096v1
+2017-12-05,"Testing gravity on cosmological scales with cosmic shear, cosmic microwave background anisotropies, and redshift-space distortions","We use a range of cosmological data to constrain phenomenological
+modifications to general relativity on cosmological scales, through
+modifications to the Poisson and lensing equations. We include cosmic microwave
+background anisotropy measurements from the Planck satellite, cosmic shear from
+CFHTLenS and DES-SV, and redshift-space distortions from BOSS data release 12
+and the 6dF galaxy survey. We find no evidence of departures from general
+relativity, with the modified gravity parameters constrained to $\Sigma_0 =
+0.05^{+0.05}_{-0.07}$ and $\mu_0 = -0.10^{+0.20}_{-0.16}$, where $\Sigma_0$ and
+$\mu_0$ refer to deviations from general relativity today and are defined to be
+zero in general relativity. We also forecast the sensitivity to those
+parameters of the full five-year Dark Energy Survey and of an experiment like
+the Large Synoptic Survey Telescope, showing a substantial expected improvement
+in the constraint on $\Sigma_0$.",1712.01846v3
+2017-12-06,Expectation of primordial gravity waves generated during inflation,"The inflationary paradigm is extremely successful regarding predictions of
+temperature anisotropies in the CMB. However, inflation also makes predictions
+for a CMB B-mode polarization, which has not been detected. Moreover, the
+standard inflationary paradigm is unable to accommodate the evolution from the
+initial state, which is assumed to be symmetric, into a non-symmetric
+aftermath. In Phys. Rev. D 96, 101301(R), we show that the incorporation of an
+element capable of explaining such a transition drastically changes the
+prediction for the shape and size of the B-mode spectrum. In particular,
+employing a realistic objective collapse model in a well-defined semiclassical
+context, we find that, while predictions of temperature anisotropies are nor
+altered (with respect to standard predictions), the B-mode spectrum gets
+strongly suppressed--in accordance with observations. Here we present an
+in-depth discussion of that analysis, together with the details of the
+calculation.",1712.02435v2
+2017-12-08,Cosmic anisotropy with Reduced Relativistic Gas,"The dynamics of cosmological anisotropies is investigated for Bianchi type I
+universe filled by a relativistic matter represented by the reduced
+relativistic gas model (RRG), with equation of state interpolating between
+radiation and matter. Previously it was shown that the interpolation is
+observed in the background cosmological solutions for homogeneous and isotropic
+universe and also for the linear cosmological perturbations. We extend the
+application of RRG to the Bianchi type I anisotropic model and find that the
+solutions evolve to the isotropic universe with the pressureless matter
+contents.",1712.03066v2
+2017-12-19,Constraints on scattering of keV--TeV dark matter with protons in the early Universe,"We present the first cosmological constraint on dark matter scattering with
+protons in the early Universe for the entire range of dark matter masses
+between 1 keV and 1 TeV. This constraint is derived from the Planck
+measurements of the cosmic microwave background (CMB) temperature and
+polarization anisotropy, and the CMB lensing anisotropy. It improves upon
+previous CMB constraints by many orders of magnitude, where limits are
+available, and closes the gap in coverage for low-mass dark matter candidates.
+We focus on two canonical interaction scenarios: spin-independent and
+spin-dependent scattering with no velocity dependence. Our results exclude
+(with 95% confidence) spin-independent interactions with cross sections greater
+than $5.3 \times 10^{-27}$ cm$^2$ for 1 keV, $3.0 \times 10^{-26}$ cm$^2$ for 1
+MeV, $1.7 \times 10^{-25}$ cm$^2$ for 1 GeV, and $1.6 \times 10^{-23}$ cm$^2$
+for 1 TeV dark matter mass. Finally, we discuss the implications of this study
+for dark matter physics and future observations.",1712.07133v2
+2017-12-21,Persistent Homology and Non-Gaussianity,"In this paper, we introduce the topological persistence diagram as a
+statistic for Cosmic Microwave Background (CMB) temperature anisotropy maps. A
+central concept in `Topological Data Analysis' (TDA), the idea of persistence
+is to represent a data set by a family of topological spaces. One then examines
+how long topological features `persist' as the family of spaces is traversed.
+We compute persistence diagrams for simulated CMB temperature anisotropy maps
+featuring various levels of primordial non-Gaussianity of local type.
+Postponing the analysis of observational effects, we show that persistence
+diagrams are more sensitive to local non-Gaussianity than previous topological
+statistics including the genus and Betti number curves, and can constrain
+$\Delta f_{NL}^{\rm loc}= 35.8$ at the 68\% confidence level on the simulation
+set, compared to $\Delta f_{NL}^{\rm loc}= 60.6$ for the Betti number curves.
+Given the resolution of our simulations, we expect applying persistence
+diagrams to observational data will give constraints competitive with those of
+the Minkowski Functionals. This is the first in a series of papers where we
+plan to apply TDA to different shapes of non-Gaussianity in the CMB and Large
+Scale Structure.",1712.08159v1
+2017-12-29,Nematic twist--bend phase in an external field,"Nematic twist--bend is the fifth nematic phase recognized in nature. This
+phase exhibits spiral orientational order, thus it is a chiral structure and it
+can be stabilized in systems composed of achiral molecules. The microscopic
+origin of this spontaneous chiral symmetry breaking is to a large extent
+unknown but phenomenologically it appears stabilized by assuming coupling
+between steric polar and orientational orderings. Understanding of how external
+fields affect the stability of this phase is of great intellectual interest and
+of relevance to potential applications. Within mesoscopic Landau--de Gennes
+theory we find that for compounds with positive anisotropy the helix unwinds to
+a polar uniaxial nematic, however negative material anisotropy gives rise to a
+rich sequence of new nematic phases obtained via mechanism of flattening the
+conical spiral.",1801.00027v1
+2018-01-04,Crystal growth and magnetic anisotropy in the spin-chain ruthenate Na$_2$RuO$_4$,"We report single crystal growth, electrical resistivity $\rho$, anisotropic
+magnetic susceptibiltiy $\chi$, and heat capacity $C_p$ measurements on the
+one-dimensional spin-chain ruthenate Na$_2$RuO$_4$. We observe variable range
+hopping (VRH) behaviour in $\rho(T)$. The magnetic susceptibility with magnetic
+field perpendicular ($\chi_\perp$) and parallel ($\chi_\parallel$) to the
+spin-chains is reported. The magnetic properties are anisotropic with
+$\chi_\perp > \chi_\parallel$ in the temperature range of measurements T
+$\approx 2$ to $305$ K with $\chi_\perp / \chi_\parallel$ $\approx 1.4$ at
+$305$ K. Analysis of the $\chi(T)$ data reveals an anisotropy in the $g$-factor
+and Van-Vleck paramagnetic contribution. An anomaly in $\chi(T)$ and a
+corresponding lambda-like anomaly in $C_p$ at $T_N = 37$ K confirms long-range
+antiferromagnetic ordering. This temperature is an order of magnitude smaller
+than the Weiss temperature $\theta \sim -250$ K and points to suppression of
+long range magnetic order due to low dimensionality. However, we were unable to
+get a satisfactory fit of the experimental $\chi(T)$ by an isolated
+one-dimensional spin-chain model, suggesting the importance of inter-chain
+interactions in Na$_2$RuO$_4$.",1801.01524v1
+2018-01-09,First-principles investigation of elastic anomalies in niobium at high pressure and temperature,"Niobium does not show any structure transition up to very high pressures.
+Nonetheless, by using density functional theory, we demonstrate in this work
+that it exhibits striking softening in elastic moduli C44 and C' at a pressure
+from 20 to 150 GPa. A novel anomaly softening in C44 from 275 to 400 GPa is
+also predicted. The physics behind these two anomalies is elaborated by
+electronic structure calculations, which revealed that they are actually
+different, with the first one directly relates to an underlying rhombohedral
+distortion whereas the latter originates in an electronic topological
+transition. The large magnitude of the softening leads to a remarkable elastic
+anisotropy in both the shear and the Young's moduli of Nb. Further
+investigation shows that thermo-electrons have an important role on these
+anomalies. This effect has not been noticed before. With increased electronic
+temperature, it is found that all anomalies (both the elastic softening and
+anisotropy) in Nb are gradually diminished, effectively giving rise to a
+temperature-induced hardening phenomenon.",1801.02915v1
+2018-01-09,Connecting CMB anisotropy and cold dark matter phenomenology via reheating,"Understanding the properties of dark matter has proved to be one of the most
+challenging problems of particle phenomenology. In this paper, we have tried to
+understand the phenomenology of dark matter in light of very well understood
+properties of cosmic microwave background (CMB) anisotropy. To connect these
+two, inflation and its subsequent evolution known as the reheating phase play
+the important role. Following the previous analysis, we first established a
+one-to-one correspondence between the CMB power spectrum and the reheating
+temperature assuming the perturbative reheating scenario. Further by
+incorporating a possible dark matter candidate through the radiation
+annihilation process during reheating and the current value of dark matter
+abundance, we constrain the dark matter parameter space through the
+inflationary power spectrum for different inflationary models.",1801.03059v3
+2018-01-17,Hartman effect for spin waves in exchange regime,"Hartman effect for spin waves tunnelling through a barrier in a thin magnetic
+film is considered theoretically. The barrier is assumed to be created by a
+locally increased magnetic anisotropy field. The considerations are focused on
+a nanoscale system operating in the exchange-dominated regime. We derive the
+formula for group delay $\tau_{gr}$ of spin wave package and show that
+$\tau_{gr}$ saturates with increasing barrier width, which is a signature of
+the Hartman effect predicted earlier for photonic and electronic systems. In
+our calculations we consider the general boundary exchange conditions which
+take into account different strength of exchange coupling between the barrier
+and its surrounding. As a system suitable for experimental observation of the
+Hartman effect we propose a CoFeB layer with perpendicular magnetic anisotropy
+induced by a MgO overlayer.",1801.05876v3
+2018-01-18,Excellent microwave and magnetic properties of La-Cu substituted Ba-hexaferrites prepared by ceramic process,"We demonstrate exceptional microwave magnetic performance of
+crystallographycally textured barium hexaferrites prepared by conventional
+ceramic method. Vibrating sample magnetometer (VSM) and rectangular cavity
+perturbation measurements indicate that bulk Ba0.8La0.2Fe11.2Cu0.2O19 samples
+exhibit a strong magnetic anisotropy field Ha of 14.6kOe, the highest remanent
+magnetization of 3.96kGs, and the lowest ferromagnetic resonance (FMR)
+linewidth of 401Oe with zero applied bias field at Q-band. Broadband
+millimeter-wave transmittance measurements determined the complex permeability
+and permittivity. The remanent magnetization, anisotropy field Ha, and
+effective linewidth were also estimated based on Schlomann's theory of the
+complex permeability. These calculated values are in good agreement with the
+VSM and FMR measurements.",1801.05945v1
+2018-01-21,Microwave fields driven domain wall motions in antiferromagnetic nanowires,"In this work, we study the microwave field driven antiferromagnetic domain
+wall motion in an antiferromagnetic nanowire, using the numerical calculations
+based on a classical Heisenberg spin model. We show that a proper combination
+of a static magnetic field plus an oscillating field perpendicular to the
+nanowire axis is sufficient to drive the domain wall propagation along the
+nanowire with the axial magnetic anisotropy. More importantly, the drift
+velocity at the resonance frequency is comparable to that induced by
+temperature gradients, suggesting that microwave field can be a very promising
+tool to control domain wall motions in antiferromagnetic nanostructures.
+Furthermore, the dependences of resonance frequency and drift velocity on the
+static and oscillating fields, the axial anisotropy, and the damping constant
+are discussed in details. This work provides useful information for the spin
+dynamics in antiferromagnetic nanostructures for spintronics applications.",1801.06748v1
+2018-01-30,Critical behavior of two-dimensional intrinsically ferromagnetic semiconductor CrI3,"CrI3, which belongs to a rare category of two-dimensional (2D) ferromagnetic
+semiconductors, is of great interest for spintronic device applications. Unlike
+CrCl3 whose magnetism presents a 2D-Heisenberg behavior, CrI3 exhibits a larger
+van der Waals gap, smaller cleavage energy, and stronger magnetic anisotropy
+which could lead to a 3D magnetic characteristic. Hence, we investigate the
+critical behavior of CrI3 in the vicinity of magnetic transition. We use the
+modified Arrott plot and Kouvel-Fisher method, and conduct critical isotherm
+analysis to estimate the critical exponents near the ferromagnetic phase
+transition. This shows that the magnetism of CrI3 follows the crossover
+behavior of a 3D-Ising model with mean field type interactions where the
+critical exponents \b{eta}, {\gamma}, and {\delta} are 0.323, 0.835, and 3.585,
+respectively, at the Curie temperature of 64 K. We propose the crossover
+behavior can be attributed to the strong uniaxial anisotropy and inevitable
+interlayer coupling. Our experiment demonstrates the applicability of crossover
+behavior to a 2D ferromagnetic semiconductor.",1801.09878v1
+2018-01-30,Anisotropic hydrodynamics with a scalar collisional kernel,"Prior studies of non-equilibrium dynamics using anisotropic hydrodynamics
+have used the relativistic Anderson-Witting scattering kernel or some variant
+thereof. In this paper, we make the first study of the impact of using a more
+realistic scattering kernel. For this purpose, we consider a conformal system
+undergoing transversally-homogenous and boost-invariant Bjorken expansion and
+take the collisional kernel to be given by the leading order 2 <-> 2 scattering
+kernel in scalar lambda phi^4. We consider both classical and quantum
+statistics in order to assess the impact of Bose enhancement on the dynamics.
+We also determine the anisotropic non-equilibrium attractor of a system subject
+to this collisional kernel. We find that, when the near-equilibrium
+relaxation-times in the Anderson-Witting and scalar collisional kernels are
+matched, the scalar kernel results in a higher degree of momentum-space
+anisotropy during the system's evolution, given the same initial conditions.
+Additionally, we find that taking into account Bose enhancement further
+increases the dynamically generated momentum-space anisotropy.",1801.10173v2
+2018-01-31,Skyrmions formation due to unconventional magnetic modes in anisotropic multi-band superconductors,"Multiband superconductors have a sufficient number of degrees of freedom to
+allow topological excitations characterized by Skyrmionic topological
+invariants. In the most common, clean s-wave multiband, systems the interband
+magnetic coupling favours composite vortex solutions, without a Skyrmionic
+topological charge. It was discussed recently that certain kinds of
+anisotropies lead to hybridisation of the interband phase difference (Leggett)
+mode with magnetic modes, dramatically changing the hydromagnetostatics of the
+system. Here we report this effect for a range of parameters that substantially
+alter the nature of the topological excitations, leading to solutions
+characterized by a nontrivial topological invariant, rather than the standard
+composite vortex solutions. This invariant is not truly topologically conserved
+but is energetically conserved, leading to a texture formed of bound
+excitations in each band, namely fractional vortices, each carrying a fraction
+of the flux quantum. We demonstrate that in this regime there is a rich
+spectrum of Skyrmion solutions, with various topological charges, that are
+robust with respect to changes of parameters of the system and present for a
+wide range of anisotropies.",1801.10463v2
+2018-01-26,Mean-field theory of differential rotation in density stratified turbulent convection,"A mean-field theory of differential rotation in a density stratified
+turbulent convection has been developed. This theory is based on a combined
+effect of the turbulent heat flux and anisotropy of turbulent convection on the
+Reynolds stress. A coupled system of dynamical budget equations consisting in
+the equations for the Reynolds stress, the entropy fluctuations and the
+turbulent heat flux has been solved. To close the system of these equations,
+the spectral tau approach which is valid for large Reynolds and Peclet numbers,
+has been applied. The adopted model of the background turbulent convection
+takes into account an increase of the turbulence anisotropy and a decrease of
+the turbulent correlation time with the rotation rate. This theory yields the
+radial profile of the differential rotation which is in agreement with that for
+the solar differential rotation.",1801.10477v2
+2018-02-08,Frustration and anisotropic exchange in ytterbium magnets with edge-shared octahedra,"We consider the structure of anisotropic exchange interactions in
+ytterbium-based insulating rare-earth magnets built from edge-sharing
+octahedra. We argue the features of trivalent ytterbium and this structural
+configuration allow for a qualitative determination of the different
+anisotropic exchange regimes that may manifest in such compounds. The validity
+of such super-exchange calculations is tested through comparison to the
+well-characterized breathing pyrochlore compound Ba$_3$Yb$_2$Zn$_5$O$_{11}$.
+With this in hand, we then consider application to three-dimensional pyrochlore
+spinels as well as two-dimensional honeycomb and triangular lattice systems
+built from such edge-sharing octahedra. We find an extended regime of robust
+emergent weak anisotropy with dominant antiferromagnetic Heisenberg
+interactions as well as smaller regions with strong anisotropy. We discuss the
+implications of our results for known compounds with the above structures, such
+as the spinels AYb$_2$X$_4$ (A = Cd, Mg, X = S, Se), the triangular compound
+YbMgGaO$_4$, which have recently emerged as promising candidates for observing
+unconventional magnetic phenomena. Finally, we speculate on implications for
+the R$_2$M$_2$O$_7$ pyrochlore compounds and some little studied honeycomb
+ytterbium magnets.",1802.03024v1
+2018-02-12,Easy-Plane Magnetic Strip as a Long Josephson Junction,"Spin-torque-biased magnetic dynamics in an easy-plane ferromagnet (EPF) is
+theoretically studied in the presence of a weak in-plane anisotropy. While this
+anisotropy spoils U(1) symmetry thereby quenching the conventional spin
+superfluidity, we show that the system instead realizes a close analog of a
+long Josephson junction (LJJ) model. The traditional magnetic-field and
+electric-current controls of the latter map respectively onto the symmetric and
+antisymmetric combinations of the out-of-plane spin torques applied at the ends
+of the magnetic strip. This suggests an alternative route towards realizations
+of superfluid-like transport phenomena in insulating magnetic systems. We study
+spin-torque-biased phase diagram, providing an analytical solution for static
+multidomain phases in the EPF. We adapt an existing self-consistency method for
+the LJJ to develop an approximate solution for the EPF dynamics. The LJJ-EPF
+mapping allows us to envision superconducting circuit functionality at elevated
+temperatures. The results apply equally to antiferromagnets with suitable
+effective free energy in terms of the N\'{e}el order instead of magnetization.",1802.04229v1
+2018-02-14,Pathway towards programmable wave anisotropy in cellular metamaterials,"In this work, we provide a proof-of-concept experimental demonstration of the
+wave control capabilities of cellular metamaterials endowed with populations of
+tunable electromechanical resonators. Each independently tunable resonator
+comprises a piezoelectric patch and a resistor-inductor shunt, and its resonant
+frequency can be seamlessly re-programmed without interfering with the cellular
+structure's default properties. We show that, by strategically placing the
+resonators in the lattice domain and by deliberately activating only selected
+subsets of them, chosen to conform to the directional features of the beamed
+wave response, it is possible to override the inherent wave anisotropy of the
+cellular medium. The outcome is the establishment of tunable spatial patterns
+of energy distillation resulting in a non-symmetric correction of the
+wavefields.",1802.04959v1
+2018-02-16,Dual phase-space cascades in 3D hybrid-Vlasov-Maxwell turbulence,"To explain energy dissipation via turbulence in collisionless, magnetized
+plasmas, the existence of a dual real- and velocity-space cascade of
+ion-entropy fluctuations below the ion gyroradius has been proposed. Such a
+dual cascade, predicted by the gyrokinetic theory, has previously been observed
+in gyrokinetic simulations of two-dimensional, electrostatic turbulence. For
+the first time we show evidence for a dual phase-space cascade of ion-entropy
+fluctuations in a three-dimensional simulation of hybrid-kinetic,
+electromagnetic turbulence. Some of the scalings observed in the energy spectra
+are consistent with a generalized theory for the cascade that accounts for the
+spectral anisotropy of critically balanced, intermittent, sub-ion-Larmor-scale
+fluctuations. The observed velocity-space cascade is also anisotropic with
+respect to the magnetic-field direction, with linear phase mixing along
+magnetic-field lines proceeding mainly at spatial scales above the ion
+gyroradius and nonlinear phase mixing across magnetic-field lines proceeding at
+perpendicular scales below the ion gyroradius. Such phase-space anisotropy
+could be sought in heliospheric and magnetospheric data of solar-wind
+turbulence and has far-reaching implications for the dissipation of turbulence
+in weakly collisional astrophysical plasmas.",1802.06133v2
+2018-02-19,Azimuthal Anisotropies at High Momentum from Purely Non-Hydrodynamic Transport,"In the limit of short mean free path, relativistic kinetic theory gives rise
+to hydrodynamics through a systematically improvable gradient expansion. In the
+present work, a systematically improvable expansion in the opposite limit of
+large mean free path is considered, describing the dynamics of particles which
+are almost, but not quite, non-interacting. This non-hydrodynamic ""eremitic""
+expansion does not break down for large gradients, and may be useful in
+situations where a hydrodynamic treatment is not applicable. As applications,
+azimuthal anisotropies at high transverse momentum in Pb+Pb and p+Pb collisions
+at $\sqrt{s}=5.02$ TeV are calculated from the first order eremitic expansion
+of kinetic theory in the relaxation time approximation.",1802.06804v3
+2018-02-20,Diode-like asymmetric transmission in ultrathin hyperbolic epsilon-near-zero slabs: extreme anisotropy mimicking chirality,"We demonstrate that a strong asymmetric transmission for forward and backward
+propagation of tilted circular polarized optical waves is supported by
+ultrathin epsilon-near-zero hyperbolic slabs. We find that, remarkably, this
+effect is solely triggered by anisotropy without resorting to any breaking of
+reciprocity and chiral symmetries or spatial nonlocal effects. In addition, we
+show that the asymmetric transmission undergoes a dramatic enhancement if the
+slab is hyperbolic in the epsilon-near-zero regime. This happens since, close
+to epsilon-near-zero point, the hyperbolic dispersion activates etalon
+resonances where extraordinary waves accumulate propagation phase even though
+the slab is ultrathin. The proposed strategy holds promise for realizing
+ultra-compact and efficient polarization devices at different frequency bands.",1802.07017v1
+2018-02-26,Quantum and Classical Phases of the Pyrochlore Heisenberg Model with Competing Interactions,"We investigate the quantum Heisenberg model on the pyrochlore lattice for a
+generic spin $S$ in the presence of nearest-neighbor $J_{1}$ and
+second-nearest-neighbor $J_{2}$ exchange interactions. By employing the
+pseudofermion functional renormalization group method, we find, for $S=1/2$ and
+$S=1$, an extended quantum-spin-liquid phase centered around $J_{2}=0$, which
+is shown to be robust against the introduction of breathing anisotropy. The
+effects of temperature, quantum fluctuations, breathing anisotropies, and a
+$J_{2}$ coupling on the nature of the scattering profile, and the pinch points,
+in particular, are studied. For the magnetic phases of the $J_{1}$-$J_{2}$
+model, quantum fluctuations are shown to renormalize phase boundaries compared
+to the classical model and to modify the ordering wave vectors of spiral
+magnetic states, while no new magnetic orders are stabilized.",1802.09546v3
+2018-02-28,Ultra-fast artificial neuron: generation of picosecond-duration spikes in a current-driven antiferromagnetic auto-oscillator,"We demonstrate analytically and numerically, that a thin film of an
+antiferromagnetic (AFM) material, having biaxial magnetic anisotropy and being
+driven by an external spin-transfer torque signal, can be used for the
+generation of ultra-short ""Dirac-delta-like"" spikes. The duration of the
+generated spikes is several picoseconds for typical AFM materials and is
+determined by the in-plane magnetic anisotropy and the effective damping of the
+AFM material. The generated output signal can consist of a single spike or a
+discrete group of spikes (""bursting""), which depends on the repetition (clock)
+rate, amplitude, and shape of the external control signal. The spike generation
+occurs only when the amplitude of the control signal exceeds a certain
+threshold, similar to the action of a biological neuron in response to an
+external stimulus. The ""threshold"" behavior of the proposed AFM spike generator
+makes possible its application not only in the traditional microwave signal
+processing but also in the future neuromorphic signal processing circuits
+working at clock frequencies of tens of gigahertz.",1802.10236v1
+2018-02-28,Effect of exchange-correlation spin-torque on spin dynamics,"A recently proposed exchange-correlation functional (Dewhurst et al.
+10.1021/acs.jctc.7b01049) with in density functional theory, which ensures that
+the exchange-correlation magnetic field is source-free, is shown to give
+non-zero internal spin-torque. This spin-torque is identically zero for all
+conventional local and semi-local functionals. Extension of this source-free
+functional to the time domain is used to study the effect of the internal
+spin-torque on the laser induced spin-dynamics in bulk Co, Ni and interfaces of
+these metals with Pt. It is shown that the internal spin-torque contribute
+significantly to spin-dynamics only when the magneto crystalline anisotropy
+energy is small, as in the case of cubic bulk materials. For surfaces or
+interfaces, where the anisotropy energy is large, these torques are too small
+to cause any significant precession of spins in early times ($<$ 100fs).
+Further more it is shown that the spin-dynamics caused by the internal
+spin-torque is slow compared to the inter-site spin transfer and spin-orbit
+mediated spin-flips.",1802.10382v1
+2018-03-01,Field-induced ordering in a random-bond quantum spin ladder compound with weak anisotropy,"The field induced quantum phase transitions in the disorder-free and
+disordered samples of the spin ladder material (CH_3)_2CHNH_3Cu(Cl_{1-x}Br_x)_3
+are studied using magnetic calorimetry and magnetic neutron diffraction on
+single crystal samples. Drastically different critical indexes and correlation
+lengths in the high field phase are found for two different orientations of the
+applied field. It is argued that for a field applied along the crystallographic
+c axis, as in previous studies [1], the transition is best described as an
+Ising transition in random field and anisotropy, rather than as a magnetic Bose
+Glass to Bose Condensate transition.
+  [1] Tao Hong, A. Zheludev, H. Manaka, and L.- P. Regnault, Phys. Rev. B 81,
+060410 (2010).",1803.00375v1
+2018-03-05,Velocity-Space Cascade in Magnetized Plasmas: Numerical Simulations,"Plasma turbulence is studied via direct numerical simulations in a
+two-dimensional spatial geometry. Using a hybrid Vlasov-Maxwell model, we
+investigate the possibility of a velocity-space cascade. A novel theory of
+space plasma turbulence has been recently proposed by Servidio {\it et al.}
+[PRL, {\bf 119}, 205101 (2017)], supported by a three-dimensional Hermite
+decomposition applied to spacecraft measurements, showing that velocity space
+fluctuations of the ion velocity distribution follow a broad-band, power-law
+Hermite spectrum $P(m)$, where $m$ is the Hermite index. We numerically explore
+these mechanisms in a more magnetized regime. We find that (1) the plasma
+reveals spectral anisotropy in velocity space, due to the presence of an
+external magnetic field (analogous to spatial anisotropy of fluid and plasma
+turbulence); (2) the distribution of energy follows the prediction $P(m)\sim
+m^{-2}$, proposed in the above theoretical-observational work; and (3) the
+velocity-space activity is intermittent in space, being enhanced close to
+coherent structures such as the reconnecting current sheets produced by
+turbulence. These results may be relevant to the nonlinear dynamics
+weakly-collisional plasma in a wide variety of circumstances.",1803.01633v2
+2018-03-12,Exploring circular polarization in the CMB due to conventional sources of cosmic birefringence,"The circular polarization of the cosmic microwave background (CMB) is usually
+taken to be zero since it is not generated by Thomson scattering. Here we
+explore the actual level of circular polarization in the CMB generated by
+conventional cosmological sources of birefringence. We consider two classes of
+mechanisms for birefringence. One is alignment of the matter to produce an
+anisotropic susceptibility tensor: the hydrogen spins can be aligned either by
+density perturbations or CMB anisotropies themselves. The other is anisotropy
+of the radiation field coupled to the non-linear response of the medium to
+electromagnetic fields: this can occur either via photon-photon scattering
+(non-linear response of the vacuum); atomic hyperpolarizability (non-linear
+response of neutral atoms); or plasma delay (non-linear response of free
+electrons). The strongest effect comes from photon-photon scattering from
+recombination at a level of $\sim 10^{-14}$ K. Our results are consistent with
+a negligible circular polarization of the CMB in comparison with the linear
+polarization or the sensitivity of current and near-term experiments.",1803.04505v2
+2018-03-13,Anisotropic susceptibilities in the honeycomb Kitaev system $α$-RuCl$_{3}$,"The magnetic insulator $\alpha$-RuCl$_{3}$ is a promising candidate to
+realize Kitaev interactions on a quasi-2D honeycomb lattice. We perform
+extensive susceptibility measurements on single crystals of
+$\alpha$-RuCl$_{3}$, including angle-dependence of the in-plane longitudinal
+and transverse susceptibilities, which reveal a unidirectional anisotropy
+within the honeycomb plane. By comparing the experimental results to a
+high-temperature expansion of a Kitaev-Heisenberg-$\Gamma$ spin Hamiltonian
+with bond anisotropy, we find excellent agreement with the observed phase shift
+and periodicity of the angle-resolved susceptibilities. Within this model, we
+show that the pronounced difference between in-plane and out-of-plane
+susceptibilities as well as the finite transverse susceptibility are rooted in
+strong symmetric off-diagonal $\Gamma$ spin exchange. The $\Gamma$ couplings
+and relationships between other terms in the model Hamiltonian are quantified
+by extracting relevant Curie-Weiss intercepts from the experimental data.",1803.04871v1
+2018-03-15,Magneto-elastic switching of magnetostrictive nanomagnets with in-plane shape anisotropy,"We theoretically study the effect of a material defect (material void) on
+switching errors associated with magneto-elastic switching of magnetization in
+elliptical magnetostrictive nanomagnets having in-plane magnetic anisotropy. We
+find that the error probability increases significantly in the presence of the
+defect, indicating that magneto-elastic switching is particularly vulnerable to
+material imperfections. Curiously, there is a critical stress value that gives
+the lowest error probability in both defect-free and defective nanomagnets. The
+critical stress is much higher in defective nanomagnets than in defect-free
+ones. Since it is more difficult to generate the critical stress in small
+nanomagnets than in large nanomagnets (having the same energy barrier for
+thermal stability), it would be a challenge to downscale magneto-elastically
+switched nanomagnets in memory and other applications where reliable switching
+is required. This is likely to be further exacerbated by the presence of
+defects.",1803.05869v3
+2018-03-16,Motion of vortices in ferromagnetic spin-1 BEC,"The paper investigates dynamics of nonsingular vortices in a ferromagnetic
+spin-1 BEC, where spin and mass superfluidity coexist in the presence of
+uniaxial anisotropy (linear and quadratic Zeeman effect). The analysis is based
+on hydrodynamics following from the Gross-Pitaevskii theory. Cores of
+nonsingular vortices are skyrmions with charge, which is tuned by uniaxial
+anisotropy and can have any fractal value between 0 and 1. There are
+circulations of mass and spin currents around these vortices. The results are
+compared with the equation of vortex motion derived earlier in the
+Landau-Lifshitz-Gilbert theory for magnetic vortices in easy-plane
+ferromagnetic insulators. In the both cases the transverse gyrotropic force
+(analog of the Magnus force in superfluid and classical hydrodynamics) is
+proportional to the charge of skyrmions in vortex cores.",1803.06939v1
+2018-03-30,"Azimuthal angle distributions of neutrons emitted from the $^9$Be($γ$,$n$) reaction with linearly polarized $γ$-rays","The electromagnetic transitions of $^9$Be with linearly polarized
+$\gamma$-rays are calculated by using the $\alpha$~+~$\alpha$~+~$n$ three-body
+model and the complex-scaled solutions of the Lippmann-Schwinger equation; the
+azimuthal angle distributions of the emitted neutrons are investigated. We
+calculate the anisotropy parameter as a function of the photon incident energy
+$E_\gamma$, and discuss how sensitive the anisotropy parameter is to nuclear
+structure and transition modes. The result suggests that the azimuthal angle
+distribution of neutrons emitted from the $^9$Be($\gamma$,$n$) reaction with
+the linearly polarized $\gamma$-rays is useful to identify the resonances in
+the final states even if it is not clearly observed in the cross section.",1803.11327v1
+2018-04-05,Derivation of a Ginzburg-Landau free energy density containing mixed gradient terms of a $p+ip$ superconductor with spin-orbit coupling,"A Ginzburg-Landau free energy for a superconducting chiral p-wave order
+parameter is derived from a two-dimensional tight binding lattice model with
+weak spin-orbit coupling included as a general symmetry-breaking field.
+Superconductivity is accounted for by a BCS-type nearest neighbor opposite-spin
+interaction where we project the potential onto the $p$-wave irreducible
+representation of the square lattice symmetry group and assume this to be the
+dominating order. The resulting free energy contains kinetic terms that mix
+components of the order parameter as well as directional gradients --- so
+called mixed gradient terms --- as a virtue of the symmetry of the order
+parameter. Spin-orbit coupling and electron-hole anisotropy lead to additional
+contributions to the coefficients of these terms, increasing the number of
+necessary phenomenological parameters by one compared to previous work, and
+leading to an increase in the coefficient measuring Fermi surface anisotropy
+for Rashba spin-orbit coupling in the continuum limit.",1804.01808v1
+2018-04-06,The lower symmetry electron-density distribution and the charge transport anisotropy in cubic dodecaboride LuB12,"High-quality single crystals of LuB12 are grown using the induction zone
+melting method. The X-ray data are collected at temperatures 293, 135, 95, 50
+K. The crystal structure of LuB12 can be refined with record low R-factor in
+the cubic Fm-3m symmetry group despite reiterated observations of the cubic
+symmetry distortions both in the unit-cell values and in the physical
+properties. A peculiar computing strategy is developed to resolve this
+contradiction. True symmetry of the electron-density distribution in LuB12 is
+proved to be much lower than cubic as a result, which correlates very
+accurately with anisotropy of transport properties of LuB12.",1804.02255v1
+2018-04-06,Integer and Fractional Quantum Hall effect in Ultra-high Quality Few-layer Black Phosphorus Transistors,"As a high mobility two-dimensional semiconductor with strong structural and
+electronic anisotropy, atomically thin black phosphorus (BP) provides a new
+playground for investigating the quantum Hall (QH) effect, including
+outstanding questions such as the functional dependence of Landau level (LL)
+gaps on magnetic field B, and possible anisotropic fractional QH states. Using
+encapsulating few-layer BP transistors with mobility up to 55,000 cm2/Vs, we
+extract LL gaps over an exceptionally wide range of B for QH states at filling
+factors {\nu}=-1 to -4, which are determined to be linear in B, thus resolving
+a controversy raised by its anisotropy. Furthermore, a fractional QH state at
+{\nu}~ -4/3 and an additional feature at -0.56+/- 0.1 are observed,
+underscoring BP as a tunable 2D platform for exploring electron interactions.",1804.02427v1
+2018-04-09,Microscopic origin of frictional rheology in dense suspensions: correlations in force space,"We develop a statistical framework for the rheology of dense, non-Brownian
+suspensions, based on correlations in a space representing forces, which is
+dual to position space. Working with the ensemble of steady state
+configurations obtained from simulations of suspensions in two dimensions, we
+find that the anisotropy of the pair correlation function in force space
+changes with confining shear stress ($\sigma_{xy}$) and packing fraction
+($\phi$). Using these microscopic correlations, we build a statistical theory
+for the macroscopic friction coefficient: the anisotropy of the stress tensor,
+$\mu = \sigma_{xy}/P$. We find that $\mu$ decreases (i) as $\phi$ is increased
+and (ii) as $\sigma_{xy}$ is increased. Using a new constitutive relation
+between $\mu$ and viscosity for dense suspensions that generalizes the
+rate-independent one, we show that our theory predicts a Discontinuous Shear
+Thickening (DST) flow diagram that is in good agreement with numerical
+simulations, and the qualitative features of $\mu$ that lead to the generic
+flow diagram of a DST fluid observed in experiments.",1804.03155v2
+2018-04-12,Ballistic one-dimensional holes with strong g-factor anisotropy in germanium,"We report experimental evidence of ballistic hole transport in
+one-dimensional quantum wires gate-defined in a strained SiGe/Ge/SiGe quantum
+well. At zero magnetic field, we observe conductance plateaus at integer
+multiples of 2e^2/h. At finite magnetic field, the splitting of these plateaus
+by Zeeman effect reveals largely anisotropic g-factors, with absolute values
+below 1 in the quantum-well plane, and exceeding 10 out of plane. This g-factor
+anisotropy is consistent with a heavy-hole character of the propagating
+valence-band states, in line with a predominant confinement in the growth
+direction. Remarkably, we observe quantized ballistic conductance in device
+channels up to 600 nm long. These findings mark an important step towards the
+realization of novel devices for applications in quantum spintronics.",1804.04674v1
+2018-04-16,Nematic Pairing from Orbital Selective Spin Fluctuations in FeSe,"FeSe is an intriguing iron-based superconductor. It presents an unusual
+nematic state without magnetism and can be tuned to increase the critical
+superconducting temperature. Recently it has been observed a noteworthy
+anisotropy of the superconducting gaps. Its explanation is intimately related
+to the understanding of the nematic transition itself. Here we show that the
+spin-nematic scenario driven by orbital-selective spin-fluctuations provides a
+simple scheme to understand both phenomena. The pairing mediated by anisotropic
+spin modes is not only orbital selective but also nematic, leading to stronger
+pair scattering across the hole and $X$ electron pocket. The delicate balance
+between orbital ordering and nematic pairing points also to a marked $k_z$
+dependence of the hole-gap anisotropy.",1804.05800v3
+2018-04-16,Triple Exponential Relaxation Dynamics in a Metallacrown-Based {$Dy^{III}Cu^{II}_5$} 3d-4f Single-Molecule Magnet,"The interplay of strong single-ion anisotropy and magnetic interactions often
+give rise to novel magnetic behavior and can provide additional routes for
+controlling magnetization dynamics. However, novel effects arising from
+interactions between lanthanide and transition-metal ions are nowadays rarely
+observed. Herein, a {$Dy^{III}Cu^{II}_5$} 3d-4f single-molecule magnet (SMM) is
+constructed as a rigid and planar [15-MC-5] metallacrown (MC), where the
+$Dy^{III}$ ion is trapped in the central pseudo-$D_{5h}$ pocket. A strong axial
+crystal field (CF) imbues the $Dy^{III}$ ion with large Ising-type magnetic
+anisotropy, and we are able to observe and model the magnetic interactions
+between the $Cu^{II}-Cu^{II}$ and $Dy^{III}-Cu^{II}$ pairs. Butterfly-shaped
+magnetic hysteresis shows clear steps at $\pm$0.4 T, coincident with level
+crossings in our model exchange Hamiltonian between the {$Cu^{II}_5$} and
+$Dy^{III}$ spin systems. Most intriguingly, this air-stable SMM exhibits three
+distinct regimes in its magnetic relaxation dynamics, all clearly displaying an
+exponential dependence on temperature.",1804.05818v1
+2018-04-16,Anisotropy of exchange stiffness based on atomic-scale magnetic properties in rare-earth permanent magnet Nd$_2$Fe$_{14}$B,"We examine the anisotropic properties of the exchange stiffness constant,
+$\mathcal{A}$, for rare-earth permanent magnet, Nd$_2$Fe$_{14}$B, by connecting
+analyses with two different scales of length, i.e., Monte Carlo (MC) method
+with an atomistic spin model and Landau-Lifshitz-Gilbert (LLG) equation with a
+continuous magnetic model. The atomistic MC simulations are performed on the
+spin model of Nd$_2$Fe$_{14}$B constructed from ab-initio calculations, and the
+LLG micromagnetics simulations are performed with the parameters obtained by
+the MC simulations. We clarify that the amplitude and the thermal property of
+$\mathcal{A}$ depend on the orientation in the crystal, which are attributed to
+the layered structure of Nd atoms and weak exchange couplings between Nd and Fe
+atoms. We also confirm that the anisotropy of $\mathcal{A}$ significantly
+affects the threshold field for the magnetization reversal (coercivity) given
+by the depinning process.",1804.05824v2
+2018-04-17,Stringent Limit on Primordial Magnetic Fields from the Cosmic Microwave Background Radiation,"Primordial magnetic fields (PMFs), being present before the epoch of cosmic
+recombination, induce small-scale baryonic density fluctuations. These
+inhomogeneities lead to an inhomogeneous recombination process that alters the
+peaks and heights of the large-scale anisotropies of the cosmic microwave
+backround (CMB) radiation. Utilizing numerical compressible MHD calculations
+and a Monte Carlo Markov chain analysis, which compares calculated CMB
+anisotropies with those observed by the \textit{WMAP} and \textit{Planck}
+satellites, we derive limits on the magnitude of putative PMFs. We find that
+the {\it total} remaining present day field, integrated over all scales, cannot
+exceed 47 pG for scale-invariant PMFs and 8.9 pG for PMFs with a violet
+Batchelor spectrum at 95\% confidence level. These limits are more than one
+order of magnitude more stringent than any prior stated limits on PMFs from the
+CMB which have not accounted for this effect.",1804.06115v3
+2018-04-18,Large perpendicular magnetic anisotropy in epitaxial Fe/MgAl2O4(001) heterostructures,"We investigated perpendicular magnetic anisotropy (PMA) and related
+properties of epitaxial Fe (0.7 nm)/MgAl2O4(001) heterostructures prepared by
+electron-beam evaporation. Using an optimized structure, we obtained a large
+PMA energy ~1 MJ/m3 at room temperature, comparable to that in
+ultrathin-Fe/MgO(001) heterostructures. Both the PMA energy and saturation
+magnetization show weak temperature dependence, ensuring wide working
+temperature in application. The effective magnetic damping constant of the 0.7
+nm Fe layer was ~0.02 using time-resolved magneto-optical Kerr effect. This
+study demonstrates capability of the Fe/MgAl2O4 heterostructure for
+perpendicular magnetic tunnel junctions, as well as a good agreement with
+theoretical predictions.",1804.06526v2
+2018-04-22,Magnetic Droplet Soliton Nucleation in Oblique Fields,"We study the auto-oscillating magnetodynamics in orthogonal spin torque
+nano-oscillators (STNOs) as a function of the out-of-plane (OOP) magnetic field
+angle. In perpendicular fields and at OOP field angles down to approximately 50
+degrees we observe the nucleation of a droplet. However, for field angles below
+50 degrees, experiments indicate that the droplet gives way to propagating spin
+waves, in agreement with our micromagnetic simulations. Theoretical
+calculations show that the physical mechanism behind these observations is the
+sign changing of spin-wave nonlinearity (SWN) by angle. In addition, we show
+that the presence of a strong perpendicular magnetic anisotropy (PMA) free
+layer in the system reverses the angular dependence of the SWN and dynamics in
+STNOs with respect to the known behavior determined for the in-plane magnetic
+anisotropy free layer. Our results are of fundamental interest in understanding
+the rich dynamics of nanoscale solitons and spin-wave dynamics in STNOs.",1804.08047v2
+2018-04-22,Are homeostatic states stable? Dynamical stability in morphoelasticity,"Biological growth is often driven by mechanical cues, such as changes in
+external pressure or tensile loading. Moreover, it is well known that many
+living tissues actively maintain a preferred level of mechanical internal
+stress, called the mechanical homeostasis. The tissue-level feedback mechanism
+by which changes of the local mechanical stresses affect growth is called a
+growth law within the theory of morphoelasticity, a theory for understanding
+the coupling between mechanics and geometry in growing and evolving biological
+materials. The goal of this article is to develop mathematical techniques to
+analyze growth laws and to explore issues of heterogeneity and growth
+stability. We discuss the growth dynamics of tubular structures, which are very
+common in biology (e.g. arteries, plant stems, airways) and model the
+homeostasis-driven growth dynamics of tubes which produces spatially
+inhomogeneous residual stress. We show that the stability of the homeostatic
+state depends nontrivially on the anisotropy of the growth response. The key
+role of anisotropy may provide a foundation for experimental testing of
+homeostasis-driven growth laws.",1804.08107v1
+2018-04-26,Orbital quantum magnetism in spin dynamics of strongly interacting magnetic lanthanide atoms,"Laser cooled lanthanide atoms are ideal candidates with which to study strong
+and unconventional quantum magnetism with exotic phases. Here, we use
+state-of-the-art closed-coupling simulations to model quantum magnetism for
+pairs of ultracold spin-6 erbium lanthanide atoms placed in a deep optical
+lattice. In contrast to the widely used single-channel Hubbard model
+description of atoms and molecules in an optical lattice, we focus on the
+single-site multi-channel spin evolution due to spin-dependent contact,
+anisotropic van der Waals, and dipolar forces. This has allowed us to identify
+the leading mechanism, orbital anisotropy, that governs molecular spin dynamics
+among erbium atoms. The large magnetic moment and combined orbital angular
+momentum of the 4f-shell electrons are responsible for these strong anisotropic
+interactions and unconventional quantum magnetism. Multi-channel simulations of
+magnetic Cr atoms under similar trapping conditions show that their
+spin-evolution is controlled by spin-dependent contact interactions that are
+distinct in nature from the orbital anisotropy in Er. The role of an external
+magnetic field and the aspect ratio of the lattice site on spin dynamics is
+also investigated.",1804.10102v1
+2018-05-02,"Energy transport in a disordered spin chain with broken U(1) symmetry: Diffusion, subdiffusion, and many-body localization","We explore the physics of the disordered XYZ spin chain using two
+complementary numerical techniques: exact diagonalization (ED) on chains of up
+to 17 spins, and time-evolving block decimation (TEBD) on chains of up to 400
+spins. Our principal findings are as follows. First, the clean XYZ spin chain
+shows ballistic energy transport for all parameter values that we investigated.
+Second, for weak disorder there is a stable diffusive region that persists up
+to a critical disorder strength that depends on the XY anisotropy. Third, for
+disorder strengths above this critical value energy transport becomes
+increasingly subdiffusive. Fourth, the many-body localization transition moves
+to significantly higher disorder strengths as the XY anisotropy is increased.
+We discuss these results, and their relation to our current physical picture of
+subdiffusion in the approach to many-body localization.",1805.01036v2
+2018-05-10,"Lattice distortion effects on the frustrated spin-1 triangular-antiferromagnet A3NiNb2O9 (A = Ba, Sr and Ca)","In the geometrically frustrated materials with the low-dimensional and small
+spin moment, the quantum fluctuation could interfere with the complicated
+interplay of the spin, electron, lattice and orbital interactions, and host
+exotic ground states such as nematic spin-state and chiral liquid phase. While
+the quantum phases of the one-dimensional chain and S - 1/2 two-dimensional
+triangular-lattice antiferromagnet (TLAF) had been more thoroughly investigated
+by both theorists and experimentalists, the work on S = 1 TLAF has been
+limited. We induced the lattice distortion into the TLAFs, A3NiNb2O9 (A = Ba,
+Sr, and Ca) with S (Ni2+) = 1, and applied the thermodynamic, magnetic and
+neutron scattering measurements. Although A3NiNb2O9 kept the non-collinear
+120{\deg} antiferromagnetic phase as the ground state, the Ni2+-lattice changed
+from the equilateral triangle (A = Ba) into isosceles triangle (A = Sr and Ca).
+The inelastic neutron scattering data were simulated by the linear spin-wave
+theory, and the competition between the single-ion anisotropy and the exchange
+anisotropy from the distorted lattice was discussed.",1805.03986v1
+2018-05-11,Azimuthal anisotropy of heavy-flavour decay electrons in p-Pb collisions at $ \sqrt{s_{\rm NN}}$ = 5.02 TeV,"Angular correlations between heavy-flavour decay electrons and charged
+particles at mid-rapidity ($|\eta| < 0.8$) are measured in p-Pb collisions at
+$\sqrt{s_{\rm NN}}$ = 5.02 TeV. The analysis is carried out for the 0-20%
+(high) and 60-100% (low) multiplicity ranges. The jet contribution in the
+correlation distribution from high-multiplicity events is removed by
+subtracting the distribution from low-multiplicity events. An azimuthal
+modulation remains after removing the jet contribution, similar to previous
+observations in two-particle angular correlation measurements for light-flavour
+hadrons. A Fourier decomposition of the modulation results in a positive
+second-order coefficient ($v_{2}$) for heavy-flavour decay electrons in the
+transverse momentum interval $1.5 < p_{\rm{T}} < 4$ GeV/$c$ in
+high-multiplicity events, with a significance larger than $5\sigma$. The
+results are compared with those of charged particles at mid-rapidity and of
+inclusive muons at forward rapidity. The $v_2$ measurement of open
+heavy-flavour particles at mid-rapidity in small collision systems could
+provide crucial information to help interpret the anisotropies observed in such
+systems.",1805.04367v2
+2018-05-15,Bianchi I model as a prototype for a cyclical Universe,"We analyze the dynamics of the Bianchi I model in the presence of stiff
+matter, an ultrarelativistic component and a small negative cosmological
+constant. We quantize this model in the framework of the polymer quantum
+mechanics, in order to introduce cut-off features in the minisuperspace
+dynamics.
+  We then apply to the polymer Wheeler-DeWitt equation, emerging from the Dirac
+constraint, an adiabatic approximation a la Vilenkin, which treats the Universe
+volume as a quasi-classical variable, becoming de facto the dynamical clock for
+the pure quantum degrees of freedom, here identified in the Universe
+anisotropies.
+  The main issue of the present analysis consists of determining a cyclical
+evolution for the Bianchi I model, oscillating between the Big-Bounce induced
+by the cut-off physics and the turning point due to the small cosmological
+constant. Furthermore, the mean value of the Universe anisotropy variables
+remains finite during the whole evolution, including the phase across the
+Big-Bounce. Such a feature, according to a suitable choice of the initial
+conditions makes the present cosmological paradigm, a viable scenario for the
+description of a possible primordial and late phases of the actual Universe.",1805.05666v1
+2018-05-21,An upper limit on the strength of the extragalactic magnetic field from ultra-high-energy cosmic-ray anisotropy,"If ultra-high-energy cosmic rays originate from extragalactic sources, the
+offsets of their arrival directions from these sources imply an upper limit on
+the strength of the extragalactic magnetic field. The Pierre Auger
+Collaboration has recently reported that anisotropy in the arrival directions
+of cosmic rays is correlated with several types of extragalactic objects. If
+these cosmic rays originate from these objects, they imply a limit on the
+extragalactic magnetic field strength of B < 0.7-2.2 x 10^-9 (lambda_B / 1
+Mpc)^-1/2 G for coherence lengths lambda_B < 100 Mpc and B < 0.7-2.2 x 10^-10 G
+at larger scales. This is comparable to existing upper limits at lambda_B = 1
+Mpc, and improves on them by a factor 4-12 at larger scales. The principal
+source of uncertainty in our results is the unknown cosmic-ray composition.",1805.07995v2
+2018-05-22,Spectral distortion anisotropies from single-field inflation,"Distortions of the Cosmic Microwave Background energy spectrum of the $\mu$
+type are sensitive to the primordial power spectrum through the dissipation of
+curvature perturbations on scales $k\simeq 50$ - $10^4\,\mathrm{Mpc}^{-1}$.
+Their angular correlation with large-scale temperature anisotropies is then
+sensitive to the squeezed limit of the primordial bispectrum. For inflationary
+models obeying the single-field consistency relation, we show that the observed
+$\mu T$ angular correlation that would correspond to the local shape vanishes
+exactly. All leading non-primordial contributions, including all non-linear
+production and projection effects, are of the ""equilateral shape"", namely
+suppressed by $k^2/{\cal H}_f^2$, where ${\cal H}_f\simeq 10^{-1}\,{\rm
+Mpc}^{-1}$ is the Hubble radius at the end of the $\mu$-era. Therefore, these
+non-primordial contributions are orthogonal to a potential local primordial
+signal (e.g. from multi-field inflation). Moreover, they are very small in
+amplitude. Our results strengthen the position of $\mu$ distortions as the
+ultimate probe of local primordial non-Gaussianity.",1805.08775v2
+2018-05-23,Renormalization of spin excitations in hexagonal HoMnO3 by magnon-phonon coupling,"Hexagonal HoMnO3, a two-dimensional Heisenberg antiferromagnet, has been
+studied via inelastic neutron scattering. A simple Heisenberg model with a
+single-ion anisotropy describes most features of the spin-wave dispersion
+curves. However, there is shown to be a renormalization of the magnon energies
+located at around 11 meV. Since both the magnon-magnon interaction and
+magnon-phonon coupling can affect the renormalization in a noncollinear magnet,
+we have accounted for both of these couplings by using a Heisenberg XXZ model
+with 1=S expansions [1] and the Einstein site phonon model [13], respectively.
+This quantitative analysis leads to the conclusion that the renormalization
+effect primarily originates from the magnon-phonon coupling, while the
+spontaneous magnon decay due to the magnon-magnon interaction is suppressed by
+strong two-ion anisotropy.",1805.08919v1
+2018-05-25,Quasiclassical theory of the spin-orbit magnetoresistance of three-dimensional Rashba metals,"The magnetoresistance of a three-dimensional Rashba material placed on top of
+a ferromagnetic insulator is theoretically investigated. In addition to the
+intrinsic Rashba spin-orbit interaction, we also consider extrinsic spin-orbit
+coupling via side-jump and skew scattering, and the Elliott-Yafet spin
+relaxation mechanism. The latter is anisotropic due to the mass anisotropy
+which reflects the noncentrosymmetric crystal structure of three-dimensional
+Rashba metals. A quasiclassical approach is employed to derive a set of coupled
+spin-diffusion equations, which are supplemented by boundary conditions that
+account for the spin-transfer torque at the interface of the bilayer. The
+magnetoresistance is fully determined by the current-induced spin polarization,
+i.e., it cannot in general be ascribed to a single (bulk) spin Hall angle. Our
+theoretical results reproduce several features of the experiments, at least
+qualitatively, and contain established phenomenological results in the relevant
+limiting cases. In particular, the anisotropy of the Elliott-Yafet spin
+relaxation mechanism plays a major role for the interpretation of the observed
+magnetoresistance.",1805.10245v1
+2018-05-29,Anisotropic Kondo pseudo-gap in URu2Si2,"A polarized electronic Raman scattering study reveals the emergence of
+symmetry dependence in the electronic Raman response of single crystalline
+URu$_{2}$Si$_{2}$ below the Kondo crossover scale $T_K\sim100K$. In particular,
+the development of a coherent Kondo pseudo-gap predominantly in the E$_g$
+channel highlights strong anisotropy in the Kondo physics in URu$_{2}$Si$_{2}$
+that has previously been neglected in theoretical models of this system. A
+calculation of the Raman vertices demonstrates that the strongest Raman vertex
+does indeed develop within the E$_g$ channel for interband transitions and
+reaches a maximum along the diagonals of the Brillouin zone, implying a
+d-wave-like geometry for the Kondo pseudo-gap. Below the hidden order phase
+transition at $T_{HO}= 17.5K$, the magnitude of the pseudo-gap is found to be
+enhanced. Moreover, the anisotropy of the pseudo-gap is similar in form to that
+proposed for the chiral d-wave (E$_g$) superconducting state that appears below
+$T_c=1.5K$.",1805.11307v2
+2018-06-01,Static Hopf Solitons and Knotted Emergent Fields in Solid-State Noncentrosymmetric Magnetic Nanostructures,"Two-dimensional topological solitons, commonly called Skyrmions, are
+extensively studied in solid-state magnetic nanostructures and promise many
+spintronics applications. However, three-dimensional topological solitons
+dubbed hopfions have not been demonstrated as stable spatially localized
+structures in solid-state magnetic materials. Here we model the existence of
+such static solitons with different Hopf index values in noncentrosymmetric
+solid magnetic nanostructures with a perpendicular interfacial magnetic
+anisotropy. We show how this surface anisotropy, along with the
+Dzyaloshinskii-Moriya interactions and the geometry of nanostructures,
+stabilize hopfions. We demonstrate knots in emergent field lines and computer
+simulate Lorentz transmission electron microscopy images of such solitonic
+configurations to guide their experimental discovery in magnetic solids.",1806.00453v3
+2018-06-02,Ultra-low damping insulating magnetic thin films get perpendicular,"A magnetic material combining low losses and large Perpendicular Magnetic
+Anisotropy (PMA) is still a missing brick in the magnonic and spintronic
+fields. We report here on the growth of ultrathin Bismuth doped
+Y$_{3}$Fe$_{5}$O$_{12}$ (BiYIG) films on Gd$_{3}$Ga$_{5}$O$_{12}$ (GGG) and
+substituted GGG (sGGG) (111) oriented substrates. A fine tuning of the PMA is
+obtained using both epitaxial strain and growth induced anisotropies. Both
+spontaneously in-plane and out-of-plane magnetized thin films can be
+elaborated. Ferromagnetic Resonance (FMR) measurements demonstrate the high
+dynamic quality of these BiYIG ultrathin films, PMA films with Gilbert damping
+values as low as 3 10$^{-4}$ and FMR linewidth of 0.3 mT at 8 GHz are achieved
+even for films that do not exceed 30 nm in thickness. Moreover, we measure
+Inverse Spin Hall Effect (ISHE) on Pt/BiYIG stacks showing that the magnetic
+insulator$'$s surface is transparent to spin current making it appealing for
+spintronic applications.",1806.00658v1
+2018-06-08,Geometry of flux attachment in anisotropic fractional quantum Hall states,"Fractional quantum Hall (FQH) states are known to possess an internal metric
+degree of freedom that allows them to minimize their energy when contrasting
+geometries are present in the problem (e.g., electron band mass and dielectric
+tensor). We investigate the internal metric of several incompressible FQH
+states by probing its response to band mass anisotropy using infinite DMRG
+simulations on a cylinder geometry. We test and apply a method to extract the
+internal metric of a FQH state from its guiding center structure factor. We
+find that the response to band mass anisotropy is approximately the same for
+states in the same Jain sequence, but changes substantially between different
+sequences. We provide a theoretical explanation of the observed behavior of
+primary states at filling $\nu = 1/m$ in terms of a minimal microscopic model
+of flux attachment.",1806.03303v1
+2018-06-11,Giant perpendicular magnetic anisotropy in Fe/III-V nitride thin films,"Large perpendicular magnetic anisotropy (PMA) in transition metal thin films
+provides a pathway for enabling the intriguing physics of nanomagnetism and
+developing broad spintronics applications. After decades of searches for
+promising materials, the energy scale of PMA of transition metal thin films,
+unfortunately, remains only about 1 meV. This limitation has become a major
+bottleneck in the development of ultradense storage and memory devices. We
+discovered unprecedented PMA in Fe thin-film growth on the $(000\bar{1})$
+N-terminated surface of III-V nitrides from first-principles calculations. PMA
+ranges from 24.1 meV/u.c. in Fe/BN to 53.7 meV/u.c. in Fe/InN.
+Symmetry-protected degeneracy between $x^2-y^2$ and $xy$ orbitals and its lift
+by the spin-orbit coupling play a dominant role. As a consequence, PMA in
+Fe/III-V nitride thin films is dominated by first-order perturbation of the
+spin-orbit coupling, instead of second-order in conventional transition
+metal/oxide thin films. This game-changing scenario would also open a new field
+of magnetism on transition metal/nitride interfaces.",1806.04162v1
+2018-06-20,Magnetic field dependence of antiferromagnetic resonance in NiO,"We report on measurements of magnetic field and temperature dependence of
+antiferromagnetic resonances in the prototypical antiferromagnet NiO. The
+frequencies of the magnetic resonances in the vicinity of 1 THz have been
+determined in the time-domain via time-resolved Faraday measurements after
+selective excitation by narrow-band superradiant terahertz (THz) pulses at
+temperatures down to 3K and in magnetic fields up to 10 T. The measurements
+reveal two antiferromagnetic resonance modes, which can be distinguished by
+their characteristic magnetic field dependencies. The nature of the two modes
+is discussed by comparison to an eight-sublattice antiferromagnetic model,
+which includes superexchange between the next-nearest-neighbor Ni spins,
+magnetic dipolar interactions, cubic magneto-crystalline anisotropy, and Zeeman
+interaction with the external magnetic field. Our study indicates that a
+two-sublattice model is insufficient for the description of spin dynamics in
+NiO, while the magnetic-dipolar interactions and magneto-crystalline anisotropy
+play important roles.",1806.07968v1
+2018-06-21,"Spin, orbital, Weyl and other glasses in topological superfluids","One of the most spectacular discoveries made in superfluid $^3$He confined in
+a nanostructured material like aerogel or nafen was the observation of the
+destruction of the long-range orientational order by a weak random anisotropy.
+The quenched random anisotropy provided by the confining material strands
+produces several different glass states resolved in NMR experiments in the
+chiral superfluid $^3$He-A and in the time-reversal-invariant polar phase. The
+smooth textures of spin and orbital order parameters in these glasses can be
+characterized in terms of the randomly distributed topological charges, which
+describe skyrmions, spin vortices and hopfions. In addition, in these skyrmion
+glasses the momentum-space topological invariants are randomly distributed in
+space. The Chern mosaic, Weyl glass, torsion glass and other exotic topological
+sates are examples of close connections between the real-space and
+momentum-space topologies in superfluid $^3$He phases in aerogel.",1806.08177v3
+2018-06-25,Stripe order and magnetic anisotropy in the $S=1$ antiferromagnet BaMoP$_2$O$_8$,"Magnetic behavior of BaMoP$_2$O$_8$ with the spatially anisotropic triangular
+arrangement of the $S=1$ Mo$^{4+}$ ions is explored using thermodynamic
+measurements, neutron diffraction, and density-functional band-structure
+calculations. A broad maximum in the magnetic susceptibility around 46\,K is
+followed by the stripe antiferromagnetic order with the propagation vector
+${\mathbf k}=(\frac{1}{2},\frac{1}{2},\frac{1}{2})$ formed below $T_N\simeq 21$
+K. This stripe phase is triggered by a pronounced one-dimensionality of the
+spin lattice, where one of the in-plane couplings, $J_2\simeq 4.6$ meV, is much
+stronger than its $J_1\simeq 0.4$ meV counterpart, and stabilized by the weak
+easy-axis anisotropy. The ordered moment of 1.42(9) $\mu_B$ at 1.5 K is
+significantly lower than the spin-only moment of 2 $\mu_B$ due to a combined
+effect of quantum fluctuations and spin-orbit coupling.",1806.09314v2
+2018-06-26,Oblique Klein tunneling in 8-Pmmn borophene p-n junctions,"The 8-\textit{Pmmn} borophene is one kind of new elemental monolayer, which
+hosts anisotropic and tilted massless Dirac fermions (MDF). The planar
+\textit{p-n} junction (PNJ) structure as the basic component of various novel
+devices based on the monolayer material has attracted increasing attention.
+Here, we analytically study the transport properties of anisotropic and tilted
+MDF across 8-\textit{Pmmn} borophene PNJ. Similar to the isotropic MDF across
+graphene junctions, perfect transmission exists but its direction departures
+the normal direction of borophene PNJ induced by the anisotropy and tilt, i.e.,
+oblique Klein tunneling. The oblique Klein tunneling does not depend on the
+doping levels in \textit{N} and \textit{P} regions of PNJ as the normal Klein
+tunneling but depends on the junction direction. Furthermore, we analytically
+derive the special junction direction for the maximal difference between
+perfect transmission direction and the normal direction of PNJ and clearly
+distinguish the respective contribution of anisotropy and tilt underlying the
+oblique Klein tunneling. In light of the rapid advances of experimental
+technologies, we expect the oblique Klein tunneling to be observable in the
+near future.",1806.09743v1
+2018-06-29,Mapping Incoherent Gravitational Wave Backgrounds,"Given the recent detection of gravitational waves from individual sources it
+is almost a certainty that some form of background of gravitational waves will
+be detected in future. The most promising candidate for such a detection are
+backgrounds made up of incoherent superposition of the signal of unresolved
+astrophysical or, backgrounds sourced by earlier cosmological events. Such
+backgrounds will also contain anisotropies about an average value. The
+information contained in the background level and any anisotropies will be
+extremely valuable as an astrophysical and cosmological probe. As such, the
+ability to reconstruct sky maps of the signal will become important as the
+sensitivity increases. We build and test a pixel--based, maximum--likelihood
+Gravitational Wave Background (GWB) map-maker that uses the cross-correlation
+of sets of generalised baselines as input. The resulting maps are a
+representation of the GWB power, or strain ""intensity"" on the sky. We test the
+algorithm by reconstructing known input maps with different baseline
+configurations. We also apply the map-maker to a subset of the Advance LIGO
+data.",1806.11360v1
+2018-07-02,Systematics of azimuthal anisotropy harmonics in proton-nucleus collisions at the LHC from the Color Glass Condensate,"Simple power counting arguments in the dilute-dense framework of the Color
+Glass Condensate (CGC) Effective Field Theory predict that even and odd
+azimuthal anisotropy harmonics of two-particle correlations in proton-nucleus
+collisions at the LHC will respectively satisfy v^2_{2n} ~ N_{ch}^0 and
+v^2_{2n+1} ~ N_{ch}, where N_{ch} denotes the number of charged particles. We
+show that these expectations are borne out qualitatively, and even
+quantitatively, within systematic uncertainties, for v_2 and v_4 in comparisons
+with data from the ATLAS collaboration. We also observe that ATLAS data for the
+v_3 azimuthal harmonic are in excellent agreement with our qualitative
+expectation; quantitative comparisons are numerically challenging at present.
+The lessons from this study fully complement those gained by the recent
+comparison of the CGC dilute-dense framework [arXiv:1805.09342] to data from
+the PHENIX collaboration on small system collisions at RHIC.",1807.00825v1
+2018-07-10,Magnetic anisotropy in HoIr$_2$Si$_2$ ($I4/mmm$),"Single crystals of HoIr$_2$Si$_2$ with the body-centered ThCr$_2$Si$_2$-type
+structure ($I4/mmm$) were grown by Bridgman method from indium flux. Single
+crystal structure determination yielded a Si-z position of 0.378(1) in the
+structure. We excluded the presence of the high temperature phase with the
+primitive CaBe$_2$Ge$_2$-type structure ($P 4/n m m$) by powder X-ray
+diffraction. Magnetic measurements on the single crystals yield a Neel
+temperature of $T_{\rm N}=22\,\rm K$. In the inverse magnetic susceptibility a
+strong anisotropy with Weiss temperatures $\Theta_{W}^{001}=26\,\rm K$ and
+$\Theta_{W}^{100}=-26\,\rm K$ occurs above $T_{\rm N}$. The effective magnetic
+moment $\mu_{\rm eff}^{001}=10.64\mu_{B}$ and $\mu_{\rm
+eff}^{100}=10.53\mu_{B}$ is close to the expected value for a free Ho$^{3+}$
+ion, $\mu_{\rm eff}^{calc}=10.6\mu_{B}$. The field dependent magnetization
+shows a step-like behaviour due to crystalline electric field effects.",1807.03657v1
+2018-07-10,Photonic spin Hall effect in hyperbolic metamaterials at visible,"Photonic spin Hall effect in transmission is a transverse beam shift of the
+out-coming beam depending on polarization of the in-coming beam. The effect can
+be significantly enhanced by materials with high anisotropy. We report the
+first experimental demonstration of the photonic spin Hall effect in a
+multilayer hyperbolic metamaterial at visible wavelengths (wavelengths of 520
+nm and 633 nm). The metamaterial is composed of alternating layers of gold and
+alumina with deeply-subwavelength thicknesses, exhibiting extremely large
+anisotropy. The angle resolved polarimetric measurements showed the shift of
+165 $\mu m$ for the metamaterial of 176 nm in thickness. Additionally the
+transverse beam shift is extremely sensitive to the variations of the incident
+angle changing theoretically by 270 $\mu m$ with one milli-radian
+($0.057^\circ$). These features can lead to minituarized spin Hall switches and
+filters with high angular resolution.",1807.03689v1
+2018-07-13,Features of the IP-Glasma,"We discuss differences between the IP-Glasma model and typical
+wounded-nucleon model like initial conditions. We point out that the IP-Glasma
+initial state is more compact in the transverse plane and produces a
+significant initial flow, both of which contribute to an increased radial flow
+in the subsequent hydrodynamic evolution. A larger bulk viscosity, compared to
+calculations that use other initial state models, is required to compensate for
+these effects and find agreement with experimental data. We further demonstrate
+the importance of the initial momentum anisotropy of the glasma for anisotropy
+measures in small collision systems such as p+Pb.",1807.05205v1
+2018-07-16,Magnetic freezing transition in a CoO/Permalloy bilayer revealed by transverse ac susceptibility,"We utilize variable-temperature, variable-frequency magneto-optical
+transverse magnetic susceptibility technique to study the static and dynamical
+magnetic properties of a thin-film CoO/Permalloy bilayer. Our measurements
+demonstrate that in the studied system, the directional asymmetry of the
+hysteresis loop is associated mainly with the difference in the reversal
+mechanisms between the two reversed states of magnetization stabilized by the
+exchange-induced uniaxial anisotropy. The latter is found to be much larger
+than the exchange-induced unidirectional anisotropy of the ferromagnet. We also
+observe an abrupt variation of the frequency-dependent imaginary part of ac
+susceptibility near the exchange bias blocking temperature, consistent with the
+magnetic freezing transition inferred from the previous time-domain studies of
+magnetic aging in similar systems. The developed measurement approach enables
+precise characterization of the dynamical and static characteristics of
+thin-film magnetic heterostructures that can find applications in
+reconfigurable magnonic and neuromorphic circuits.",1807.05990v2
+2018-07-17,Magnetic ordering with an XY-like anisotropy in the honeycomb lattice iridates ZnIrO$_3$ and MgIrO$_3$ synthesized via a metathesis reaction,"We have successfully synthesized the novel antiferromagnets with Ir$^{4+}$
+honeycomb lattice ZnIrO$_3$ and MgIrO$_3$ and investigated their magnetic and
+thermodynamic properties. The two iridates are isomorphic but exhibit
+qualitatively different magnetic properties. ZnIrO$_3$ shows antiferromagnetic
+ordering below 46.6 K, whereas MgIrO$_3$ displays weak ferromagnetic behavior
+below 31.8 K owing to formation of a canted antiferromagnetic ordering. The
+measurement of magnetic susceptibility with using an oriented powder sample
+revealed the presence of an XY-like magnetic anisotropy and a tilting magnetic
+structure which is possibly stabilized by the Kitaev interaction. Moreover,
+magnetization curves of MgIrO3 and ZnIrO3 up to 60 T show different behaviors,
+demonstrating that each magnetic ground state is different with each other. We
+discuss the difference in the ground state between MgIrO$_3$ and ZnIrO$_3$ from
+the viewpoint a magnetic model consisting of the Kitaev and
+Dzyaloshinskii-Moriya interactions with the spin frustration effect on the
+honeycomb lattice.",1807.06273v2
+2018-07-17,Field-free spin-orbit torque switching from geometrical domain wall pinning,"Spin-orbit torques, which utilize spin currents arising from the spin-orbit
+coupling, offer a novel method to electrically switch the magnetization with
+perpendicular anisotropy. However, the necessity of an external magnetic field
+to achieve a deterministic switching is an obstacle for realizing practical
+spin-orbit torque devices with all-electric operation. Here, we report a
+field-free spin-orbit torque switching by exploiting the domain wall motion in
+an anti-notched microwire with perpendicular anisotropy, which exhibits
+multi-domain states stabilized by the domain wall surface tension. The
+combination of spin-orbit torque, Dzyaloshinskii-Moriya interaction, and domain
+wall surface tension induced geometrical pinning allows a deterministic control
+of the domain wall and offers a novel method to achieve a field-free spin-orbit
+torque switching. Our work demonstrates the proof of concept of a perpendicular
+memory cell which can be readily adopted in a three-terminal magnetic memory.",1807.06287v1
+2018-07-17,Impact of further-range exchange and cubic anisotropy on magnetic excitations in the fcc kagome antiferromagnet IrMn3,"Exchange interactions up to fourth nearest neighbor are shown within a
+classical local-moment Heisenberg approach to be important to model inelastic
+neutron scattering data on the fcc kagome antiferromagnet IrMn$_3$. Spin wave
+frequencies are calculated using the torque equation and the magnetic
+scattering function, $S({\bf Q},\omega)$, is determined by a Green's function
+method, as an extension of our previous work, LeBlanc et al, Phys. Rev. B 90,
+144403 (2014). Results are compared with intensity contour data on powder
+samples of ordered IrMn$_3$, where magnetic Mn ions occupy lattice sites of ABC
+stacked kagome planes. Values of exchange parameters taken from DFT
+calculations used in our model provide good agreement with the experimental
+results only if further-neighbor exchange is included. Estimates of the
+observed energy gap support the existence of strong cubic anisotropy predicted
+by DFT calculations.",1807.06659v1
+2018-07-18,New angles on standard force fields: towards a general approach for treating atomic-level anisotropy,"Nearly all standard force fields employ the 'sum-of-spheres' approximation,
+which models intermolecular interactions purely in terms of interatomic
+distances. Nonetheless, atoms in molecules can have significantly non-spherical
+shapes, leading to interatomic interaction energies with strong orientation
+dependencies. Neglecting this 'atomic-level anisotropy' can lead to significant
+errors in predicting interaction energies. Herein we propose a simple,
+transferable, and computationally-efficient model (MASTIFF) whereby
+atomic-level orientation dependence can be incorporated into ab initio
+intermolecular force fields. MASTIFF includes anisotropic exchange-repulsion,
+charge penetration, and dispersion effects, in conjunction with a standard
+treatment of anisotropic long-range (multipolar) electrostatics. To validate
+our approach, we benchmark MASTIFF against various sum-of-spheres models over a
+large library of intermolecular interactions between small organic molecules.
+MASTIFF achieves quantitative accuracy with respect to both high-level
+electronic structure theory and experiment, thus showing promise as a basis for
+'next-generation' force field development.",1807.07096v1
+2018-07-24,Finite element approximations for near-incompressible and near-inextensible transversely isotropic bodies,"This work comprises a detailed theoretical and computational study of the
+boundary value problem for transversely isotropic linear elastic bodies.
+General conditions for well-posedness are derived in terms of the material
+parameters. The discrete form of the displacement problem is formulated for
+conforming finite element approximations. The error estimate reveals that
+anisotropy can play a role in minimizing or even eliminating locking behaviour,
+for moderate values of the ratio of Young's moduli in the fibre and transverse
+directions. In addition to the standard conforming approximation an alternative
+formulation, involving under-integration of the volumetric and extensional
+terms in the weak formulation, is considered. The latter is equivalent to
+either a mixed or a perturbed Lagrangian formulation, analogously to the
+well-known situation for the volumetric term. A set of numerical examples
+confirms the locking-free behaviour in the near-incompressible limit of the
+standard formulation with moderate anisotropy, with locking behaviour being
+clearly evident in the case of near-inextensibility. On the other hand,
+under-integration of the extensional term leads to extensional locking-free
+behaviour, with convergence at superlinear rates.",1807.09168v2
+2018-07-24,Mechanism of substrate-induced anisotropic growth of monolayer WS2 by kinetic Monte Carlo simulations,"Controlled anisotropic growth of two-dimensional materials provides an
+approach for the synthesis of large single crystals and nanoribbons, which are
+promising for applications as low-dimensional semiconductors and in
+next-generation optoelectronic devices. In particular, the anisotropic growth
+of transition metal dichalcogenides induced by the substrate is of great
+interest due to its operability. To date, however, their substrate-induced
+anisotropic growth is typically driven by the optimization of experimental
+parameters without uncovering the fundamental mechanism. Here, the anisotropic
+growth of monolayer tungsten disulfide on an ST-X quartz substrate is achieved
+by chemical vapor deposition, and the mechanism of substrate-induced
+anisotropic growth is examined by kinetic Monte Carlo simulations. These
+results show that, besides the variation of substrate adsorption, the chalcogen
+to metal (C/M) ratio is a major contributor to the large growth anisotropy and
+the polarization of undergrowth and overgrowth; either perfect isotropy or high
+anisotropy can be expected when the C/M ratio equals 2.0 by properly
+controlling the linear relationship between gas flux and temperature.",1807.09323v2
+2018-07-25,Hamiltonian theory for Quantum Hall systems in a tilted magnetic field: robustness of activation gaps,"We use the Hamiltonian theory developed by Shankar and Murthy to study a
+quantum Hall system in a tilted magnetic field. With a finite width of the
+system in the $z$ direction, the parallel component of the magnetic field
+introduces anisotropy into the effective two-dimensional interactions. The
+effects of such anisotropy can be effectively captured by the recently proposed
+generalized pseudo-potentials. We find that the off-diagonal components of the
+pseudo-potentials lead to mixing of composite fermions Landau levels, which is
+a perturbation to the picture of $p$ filled Landau levels in composite-fermion
+theory. By changing the internal geometry of the composite fermions, such a
+perturbation can be minimized and one can find the corresponding activation
+gaps for different tilting angles, and we calculate the associated optimal
+metric. Our results show that the activation gap is remarkably robust against
+the in-plane magnetic field in the lowest Landau level.",1807.09677v1
+2018-07-24,Electromagnetic effect on anisotropic scalar field collapse in higher curvature gravity,"We consider a `Scalar-Maxwell-Einstein-Gauss-Bonnet' theory in four
+dimension, where the scalar field couples non-minimally with the Gauss-Bonnet
+(GB) term. This coupling with the scalar field ensures the non topological
+character of the GB term. In such higher curvature scenario, we explore the
+effect of electromagnetic field on scalar field collapse. Our results reveal
+that the presence of a time dependent electromagnetic field requires an
+anisotropy in the background spacetime geometry and such anisotropic spacetime
+allows a collapsing solution for the scalar field. The singularity formed as a
+result of the collapse is found to be a curvature singularity which may be
+point like or line like depending on the strength of the anisotropy. We also
+show that the singularity is always hidden from exterior by an apparent
+horizon.",1807.10140v1
+2018-08-10,Tunneling anomalous Hall effect in a ferroelectric tunnel junction,"We report on a theoretical study on the tunneling anomalous Hall effect
+(TAHE) in a ferroelectric tunnel junction (FTJ), resulting from spin-orbit
+coupling (SOC) in the ferroelectric barrier. For ferroelectric barriers with
+large SOC, such as orthorhombic HfO2 and BiInO3, we predict values of the
+tunneling anomalous Hall conductivity (TAHC) measurable experimentally. We
+demonstrate strong anisotropy in TAHC depending on the type of SOC. For the SOC
+with equal Rashba and Dresselhaus parameters, we predict the perfect anisotropy
+with zero TAHC for certain magnetization orientations. The TAHC changes sign
+with ferroelectric polarization reversal providing a new functionality of FTJs.
+Conversely, measuring the TAHC as a function of magnetization orientation
+offers an efficient way to quantify the type of SOC in the insulating barrier.
+Our results provide a new insight into the TAHE and open avenues for potential
+device applications.",1808.03583v2
+2018-08-11,Walker solution for Dzyaloshinskii domain wall in ultrathin ferromagnetic films,"We analyze the electric current and magnetic field driven domain wall motion
+in perpendicularly magnetized ultrathin ferromagnetic films in the presence of
+interfacial Dzyaloshinskii-Moriya interaction and both out-of-plane and
+in-plane uniaxial anisotropies. We obtain exact analytical Walker-type
+solutions in the form of one-dimensional domain walls moving with constant
+velocity due to both spin-transfer torques and out-of-plane magnetic field.
+These solutions are embedded into a larger family of propagating solutions
+found numerically. Within the considered model, we find the dependencies of the
+domain wall velocity on the material parameters and demonstrate that adding
+in-plane anisotropy may produce domain walls moving with velocities in excess
+of 500 m/s in realistic materials under moderate fields and currents.",1808.03772v2
+2018-08-11,Biaxial layering transition of hard rod-like particles in narrow slit-like pores,"The phase behavior of hard rectangular rods with length L and diameter D is
+studied in a narrow slit-like pore using the Parsons-Lee density functional
+theory. Using the restricted orientation approximation, we find strong
+adsorption at the walls with planar ordering, second order uniaxial-biaxial
+ordering transitions and first order layering transitions. The layering
+transition takes place between two fluids having n and n+1 layers, where the
+layer spacing is in the order of D. In the case of weak shape anisotropy
+(L/D=3), the coexisting fluids can be either uniaxial or biaxial, while both
+phases are found to be biaxial for L/D=6 and L/D=9. Interestingly, even two or
+more layering transitions can be observed with increasing density at a given
+shape anisotropy and pore width.",1808.03839v1
+2018-08-12,Measurements and implications of cosmic ray anisotropies from TeV to trans-EeV energies,"Important observational results have been recently reported on the angular
+distributions of cosmic rays at all energies, calling into question the
+perception of cosmic rays a decade ago. These results together with their
+in-progress interpretations are summarised in this review paper, covering both
+large-scale and small-scale anisotropies from TeV energies to the highest ones.
+While the magnetic field in the Galaxy has long been considered as an external
+data imprinting a quasi-random walk to particles and thus shaping the angular
+distributions of Galactic cosmic rays through the induced average density
+gradient, the information encompassed in the angular distributions in the
+TeV--PeV energy range appear today as a promising tool to infer some properties
+of the local magnetic field environments. At the highest energies, the
+extragalactic origin of the particles has been recently determined
+observationally. While no discrete source of ultrahigh-energy cosmic rays has
+been identified so far, the noose is tightening around nearby extragalactic
+objects, and some prospects are discussed.",1808.03940v1
+2018-08-16,Jamming and percolation properties of random sequential adsorption with relaxation,"The random sequential adsorption (RSA) model is a classical model in
+Statistical Physics for adsorption on two-dimensional surfaces. Objects are
+deposited sequentially at random and adsorb irreversibly on the landing site,
+provided that they do not overlap any previously adsorbed object. The kinetics
+of adsorption ceases when no more objects can be adsorbed (jamming state).
+Here, we investigate the role of post-relaxation on the jamming state and
+percolation properties of RSA of dimers on a two-dimensional lattice. We
+consider that, if the deposited dimer partially overlaps with a previously
+adsorbed one, a sequence of dimer displacements may occur to accommodate the
+new dimer. The introduction of this simple relaxation dynamics leads to a more
+dense jamming state than the one obtained with RSA without relaxation. We also
+consider the anisotropic case, where one dimer orientation is favored over the
+other, finding a non-monotonic dependence of the jamming coverage on the
+strength of anisotropy. We find that the density of adsorbed dimers at which
+percolation occurs is reduced with relaxation, but the value depends on the
+strength of anisotropy.",1808.05637v1
+2018-08-19,Quantized excitation spectra by magnon confinement in quasi-one-dimensional S=1 spin systems,"We apply the infinite time-evolving-block-decimation algorithm to calculate
+the dynamical spin-structure factors of the quasi-one-dimensional (q1D) S=1
+antiferromagnetic spin system with the single-ion anisotropy and the bond
+alternation. We find that excitation continuum originating from magnons is
+quantized, when the staggered field induced by the weak inter-chain interaction
+is taken into account. The excitation energies of the quantized excitation
+spectra are well explained by negative zeros of the Airy functions, when the
+easy-axis anisotropy is strong and the ground state is located deep in the
+N\'eel phase. This quantization of the magnon continuum is a counterpart of the
+spinon confinement, which has been recently discussed in q1D S=1/2
+antiferromagnets. We further show that, when the staggered field exists, the
+quantized excitation spectra appear the phase boundary between the Haldane
+phase and the N\'eel phase of the phase diagram without the staggered field.
+However, the quantized excitation spectra disappear in the singlet dimer phase.",1808.06270v2
+2018-08-27,Sign Reversal and Tunability of Exchange Bias in Nanoscale AuFe Alloy Film: A New Material for Spintronic Application,"We report here sign reversal and tunability of exchange bias in AuFe
+cosputtered films of thickness about 63 nm. As deposited film exhibits exchange
+bias effect at room temperature without external triggering field and its
+magnitude increases gradually with decrease in temperature down to 5 K. Upon
+irradiation with 100 MeV Au9+ ions at a fluence of 5*1013 ions/cm2, hysteresis
+loop shifts completely from origin towards positive field side at room
+temperature and reverses sign when temperature is reduced to 5 K as studied by
+SQUID magnetometry. A well defined uniaxial magnetic anisotropy has been seen
+by magneto optical Kerr effect (MOKE) in as deposited film as well as in
+irradiated one. The results are explained on the basis of stress induced
+magnetic anisotropy in thin films.",1808.08694v1
+2018-08-30,Ground-state phase diagram of the $S = 1$ one-dimensional Kondo lattice model with a uniaxial anisotropy under transverse fields,"We study the effects of transverse magnetic fields on the $S=1$
+one-dimensional Kondo lattice model with a uniaxial anisotropy using the
+density matrix renormalization group. The model can be regarded as a simplified
+one for analyzing the Ising ferromagnetic superconductor URhGe. We find various
+phases such as ferromagnetic and antiferromagnetic phases, Kondo plateau (KP)
+phases, Tomonaga-Luttinger liquids, and fully polarized phases. In the KP
+phase, a pseudoplateau emerges in the magnetization due to strongly bound pairs
+between the local and the conduction electron spins. This is why we call this
+phase the Kondo plateau. At the critical field between the ferromagnetic and KP
+phases, we find metamagnetic behavior in the magnetization curve. We discuss
+various correlation functions and the Friedel oscillations in detail, and the
+experimental data under transverse magnetic fields in URhGe are discussed on
+the basis of the present results.",1808.10142v3
+2018-09-04,Formation and Control of Twin Domains in the Pyrochlore Oxide Cd2Re2O7,"The successive phase transitions of the pyrochlore oxide Cd2Re2O7 are studied
+by polarizing microscopy and magnetic susceptibility measurements. The
+formation of twin domains is visualized in the polarizing images of a pristine
+(111) crystal surface upon cooling through the cubic-to-tetragonal transition
+at Ts1 ~ 200 K. Moreover, a dramatic change in the twinning pattern is observed
+at Ts2 ~120 K, which suggests that the tetragonal c axis flips as the strain
+changes its direction at the tetragonal-to-tetragonal transition. Magnetic
+susceptibility measurements reveal significant domain alignment upon cooling
+across Ts1 and Ts2 in a magnetic field of 7 T, which are due to ~10% anisotropy
+in the magnetic susceptibility for the low-temperature phases. Interestingly,
+the anisotropy is reversed at Ts2: \c{hi}c < \c{hi}a above Ts2 and vice versa
+below Ts2.",1809.00771v2
+2018-09-25,Effect of dispersity of particle length on the electrical conductivity of the two-dimensional systems,"By means of computer simulation, we examined effect of dispersity of filler
+length on electrical conductivity of two-dimensional (2D) composites with
+rod-like fillers. Continuous approach has been used. Highly conductive
+zero-width rod-like particles were deposited uniformly with given anisotropy
+onto a poorly conductive substrate. Length of particles varied according to the
+lognormal distribution. Our simulation evidenced that slightly disordered
+systems may have both the high figure of merit, i.e., both high electrical
+conductivity and the optical transmission simultaneously, and the high
+electrical anisotropy.",1809.09969v1
+2018-09-26,Incipient and well-developed entropy plateaus in spin-S Kitaev models,"We present results on entropy and heat-capacity of the spin-S
+honeycomb-lattice Kitaev models using high-temperature series expansions and
+thermal pure quantum (TPQ) state methods. We study models with anisotropic
+couplings $J_z=1\ge J_x=J_y$ for spin values 1/2, 1, 3/2, and 2. We show that
+for $S>1/2$, any anisotropy leads to well developed plateaus in the entropy
+function at an entropy value of $\frac{1}{2}\ln{2}$, independent of $S$.
+However, in the absence of anisotropy, there is an incipient entropy plateau at
+$S_{max}/2$, where $S_{max}$ is the infinite temperature entropy of the system.
+We discuss possible underlying microscopic reasons for the origin and
+implications of these entropy plateaus.",1809.10112v2
+2018-09-27,Evolution of two-time correlations in dissipative quantum spin systems: aging and hierarchical dynamics,"We consider the evolution of two-time correlations in the quantum XXZ
+spin-chain in contact with an environment causing dephasing. Extending
+quasi-exact time-dependent matrix product state techniques to consider the
+dynamics of two-time correlations within dissipative systems, we uncover the
+full quantum behavior for these correlations along all spin directions.
+Together with insights from adiabatic elimination and kinetic Monte Carlo, we
+identify three dynamical regimes. For initial times, their evolution is
+dominated by the system unitary dynamics and depends on the initial state and
+the Hamiltonian parameters. For weak spin-spin interaction anisotropy, after
+this initial dynamical regime, two-time correlations enter an algebraic scaling
+regime signaling the breakdown of time-translation invariance and the emergence
+of aging. For stronger interaction anisotropy, these correlations first go
+through a stretched exponential regime before entering the algebraic one. Such
+complex relaxation arises due to the competition between the proliferation
+dynamics of energetically costly excitations and their motion. As a result,
+dissipative heating dynamics of spin systems can be used to probe the entire
+spectrum of the underlying Hamiltonian.",1809.10464v1
+2018-10-04,Exotic criticality in the dimerized spin-1 $XXZ$ chain with single-ion anisotropy,"We consider the dimerized spin-1 $XXZ$ chain with single-ion anisotropy $D$.
+In absence of an explicit dimerization there are three phases: a large-$D$, an
+antiferromagnetically ordered and a Haldane phase. This phase structure
+persists up to a critical dimerization, above which the Haldane phase
+disappears. We show that for weak dimerization the phases are separated by
+Gaussian and Ising quantum phase transitions. One of the Ising transitions
+terminates in a critical point in the universality class of the dilute Ising
+model. We comment on the relevance of our results to experiments on
+quasi-one-dimensional anisotropic spin-1 quantum magnets.",1810.02195v3
+2018-10-04,Fourier Domain Rotational Anisotropy Second Harmonic Generation,"We describe a novel scheme of detecting rotational anisotropy second harmonic
+generation (RA-SHG) signals using a lock-in amplifier referenced to a fast
+scanning RA-SHG apparatus. The method directly measures the $n^{th}$ harmonics
+of the scanning frequency corresponding to SHG signal components of $C_n$
+symmetry that appear in a Fourier series expansion of a general RA-SHG signal.
+GaAs was used as a test sample allowing comparison of point-by-point averaging
+with the lock-in based method. When divided by the $C_\infty$ signal component,
+the lock-in detected data allowed for both self-referenced determination of
+ratios of $C_n$ components of up to 1 part in 10$^4$ and significantly more
+sensitive measurement of the relative amount of different $C_n$ components when
+compared with conventional methods.",1810.02310v1
+2018-10-10,An edge-based pressure stabilisation technique for finite elements on arbitrarily anisotropic meshes,"In this article, we analyse a stabilised equal-order finite element
+approximation for the Stokes equations on anisotropic meshes. In particular, we
+allow arbitrary anisotropies in a sub-domain, for example along the boundary of
+the domain, with the only condition that a maximum angle is fulfilled in each
+element.This discretisation is motivated by applications on moving domains as
+arising e.g. in fluid-structure interaction or multiphase-flow problems. To
+deal with the anisotropies, we define a modification of the original Continuous
+Interior Penalty stabilisation approach. We show analytically the discrete
+stability of the method and convergence of order ${\cal O}(h^{3/2})$ in the
+energy norm and ${\cal O}(h^{5/2})$ in the $L^2$-norm of the velocities. We
+present numerical examples for a linear Stokes problem and for a non-linear
+fluid-structure interaction problem, that substantiate the analytical results
+and show the capabilities of the approach.",1810.04766v1
+2018-10-13,Noise in the helical edge channel anisotropically coupled to a local spin,"We calculate the frequency-dependent shot noise in the edge states of a
+two-dimensional topological insulator coupled to a magnetic impurity with spin
+$S=1/2$ of arbitrary anisotropy. If the anisotropy is absent, the noise is
+purely thermal at low frequencies, but tends to the Poissonian noise of the
+full current $I$ at high frequencies. If the interaction only flips the
+impurity spin but conserves those of electrons, the noise at high voltages
+$eV\gg T$ is frequency-independent. Both the noise and the backscattering
+current $I_{bs}$ saturate at voltage-independent values. Finally, if the
+Hamiltonian contains all types of non-spin-conserving scattering, the noise at
+high voltages becomes frequency-dependent again. At low frequencies, its ratio
+to $2eI_{bs}$ is larger than 1 and may reach 2 in the limit $I_{bs}\to 0$. At
+high frequencies it tends to 1.",1810.05831v1
+2018-10-22,Amplitude mode in the planar triangular antiferromagnet Na$_{0.9}$MnO$_2$,"Amplitude modes arising from symmetry breaking in materials are of broad
+interest in condensed matter physics. These modes reflect an oscillation in the
+amplitude of a complex order parameter, yet are typically unstable and decay
+into oscillations of the order parameter's phase. This renders stable amplitude
+modes rare, and exotic effects in quantum antiferromagnets have historically
+provided a realm for their detection. Here we report an alternate route to
+realizing amplitude modes in magnetic materials by demonstrating that an
+antiferromagnet on a two-dimensional anisotropic triangular lattice
+($\alpha$-Na$_{0.9}$MnO$_2$) exhibits a long-lived, coherent oscillation of its
+staggered magnetization field. Our results show that geometric frustration of
+Heisenberg spins with uniaxial single-ion anisotropy can renormalize the
+interactions of a dense two-dimensional network of moments into largely
+decoupled, one-dimensional chains that manifest a longitudinally polarized
+bound state. This bound state is driven by the Ising-like anisotropy inherent
+to the Mn$^{3+}$ ions of this compound.",1810.09518v1
+2018-10-24,First analysis of GLE 72 event on 10 September 2017: Spectral and anisotropy characteristics,"Using neutron monitor and space-borne data we performed an analysis of the
+second ground level enhancement of solar cycle 24, namely the event of 10
+September 2017 (GLE 72) and derive the spectral and angular characteristics of
+GLE particles. We employ new neutron monitor yield function and a recently
+proposed model based on optimization procedure. The method consists of
+simulation of particle propagation in a model magnetosphere in order to derive
+the cut-off rigidity and neutron monitor asymptotic directions. Subsequently
+the rigidity spectrum and anisotropy of GLE particles are obtained in their
+dynamical evolution during the event on the basis of inverse problem solution.
+The derived angular distribution and spectra are briefly discussed.",1810.10536v1
+2018-10-31,Anisotropy of Dirac cones and van Hove singularity in an organic Dirac fermion system,"We propose an experimental method to examine the in-plane anisotropy of
+electronic structure in layered conductors. In the method, we measure the
+interlayer magnetoresistance as a function of in-plane magnetic field
+orientation. We applied it to an organic Dirac fermion system a-(BEDT-TTF)2I3
+to experimentally determine the orientation of the anisotropic Dirac cones. It
+is concluded that the long axis of the elliptic constant-energy contours of the
+Dirac cone is tilted by approximately -30 deg from the crystalline a-axis to
+b-axis under hydrostatic pressures. Additionally, we observed a signature of
+van Hove singularity (which is a saddle point of the band dispersion) at 30-40
+K above or below the Dirac point. The ridgeline of the saddle point is
+estimated as almost parallel to the crystalline b-axis.",1810.13079v1
+2018-10-31,Reservoir computing with dipole-coupled nanomagnets,"The feasibility of reservoir computing based on dipole-coupled nanomagnets is
+demonstrated using micro-magnetic simulations. The reservoir consists of an
+2x10 array of nanomagnets. The static-magnetization directions of the
+nanomagnets are used as reservoir states. To update these states, we change the
+magnetization of one nanomagnet according to a single-bit-sequential signal. We
+also change the uniaxial anisotropy of the other nanomagnets using a
+voltage-induced magnetic-anisotropy change to enhance information flow,
+storage, and linear/nonlinear calculations. Binary tasks with AND, OR, and XOR
+operations were performed to evaluate the performance of the magnetic-array
+reservoir. The reservoir-computing output matrix was found to be trainable to
+perform AND, OR, and XOR operations with an input delay of up to three bits.",1810.13140v2
+2018-10-31,Fast Reflective Optic-Based Rotational Anisotropy Nonlinear Harmonic Generation Spectrometer,"We present a novel Rotational Anisotropy Nonlinear Harmonic Generation
+(RA-NHG) apparatus based primarily upon reflective optics. The data acquisition
+scheme used here allows for fast accumulation of RA-NHG traces, mitigating low
+frequency noise from laser drift, while permitting real-time adjustment of
+acquired signals with significantly more data points per unit angle rotation of
+the optics than other RA-NHG setups. We discuss the design and construction of
+the optical and electronic components of the device and present example data
+taken on a GaAs test sample at a variety of wavelengths. The RA-second harmonic
+generation data for this sample show the expected four-fold rotational symmetry
+across a broad range of wavelengths, while those for RA-third harmonic
+generation exhibit evidence of cascaded nonlinear processes possible in
+acentric crystal structures.",1811.01862v1
+2018-11-06,Chiral-induced switching of antiferromagnet spins in a confined nanowire,"In the development of spin-based electronic devices, a particular challenge
+is the manipulation of the magnetic state with high speed and low power
+consumption. Although research has focused on the current-induced spin-orbit
+torque based on strong spin-orbit coupling, the charge-based and the
+torque-driven devices have fundamental limitations: Joule heating, phase
+mismatching and overshooting. In this work, we investigate numerically and
+theoretically alternative switching scenario of antiferromagnetic insulator in
+one-dimensional confined nanowire sandwiched with two electrodes. As the
+electric field could break inversion symmetry and induce Dzyaloshinskii-Moriya
+interaction and pseudo-dipole anisotropy, the resulting spiral texture takes
+symmetric or antisymmetric configuration due to additional coupling with the
+crystalline anisotropy. Therefore, by competing two spiral states, we show that
+the magnetization reversal of antiferromagnets is realized, which is valid in
+ferromagnetic counterpart. Our finding provides promising opportunities to
+realize the rapid and energy-efficient electrical manipulation of magnetization
+for future spin-based electronic devices.",1811.02200v2
+2018-11-08,"Comment on the article ""Anisotropies in the astrophysical gravitational-wave background: The impact of black hole distributions"" by A.C. Jenkins et al. [arXiv:1810.13435]","We investigate the discrepancy pointed out by Jenkins et al. in Ref. [1]
+between the predictions of anisotropies of the astrophysical gravitational wave
+(GW) background, derived using different methods in Cusin et al. [2] and in
+Jenkins et al. [3]. We show that this discrepancy is not due to our treatment
+of galaxy clustering, contrary to the claim made in Ref. [1] and we show that
+our modeling of clustering gives results in very good agreement with
+observations. Furthermore we show that the power law spectrum used in Refs. [1]
+and [3] to describe galaxy clustering is incorrect on large scales and leads to
+a different scaling of the multipoles $C_\ell$. Moreover, we also explain that
+the analytic derivation of the gravitational wave background correlation
+function in Refs. [1] and [3] is mathematically ill-defined and predicts an
+amplitude of the angular power spectrum which depends on the (arbitrary) choice
+of a non-physical cut-off.",1811.03582v2
+2018-11-12,Thermopower in an anisotropic two-dimensional Weyl semimetal,"We investigate the generation of an electric current from a temperature
+gradient in a two-dimensional Weyl semimetal with anisotropy, in both the
+presence and absence of a quantizing magnetic field. We show that the
+anisotropy leads to doping dependences of thermopower and thermal
+conductivities which are different from those in isotropic Dirac materials.
+Additionally, we find that a quantizing magnetic field in such systems leads to
+an interesting magnetic field dependence of the longitudinal thermopower,
+resulting in unsaturated thermoelectric coefficients. Thus the results
+presented here will serve as a guide to achieving high thermopower and a
+thermoelectric figure-of-merit in graphene-based materials, as well as organic
+conductors such as $\alpha$-(BEDT-TTF)$_2$I$_3$.",1811.04952v6
+2018-11-13,Spin-orbit torques acting upon a perpendicularly-magnetized Py layer,"We show that Py, a commonly-used soft ferromagnetic material with weak
+anisotropy, can become perpendicularly-magnetized while depositing on Ta buffer
+layer with Hf or Zr insertion layers (ILs) and MgO capping layer. By using two
+different approaches, namely harmonic voltage measurement and hysteresis loop
+shift measurement, the dampinglike spin-orbit torque (DL-SOT) efficiencies from
+Ta/IL/Py/IL/MgO magnetic heterostructures with perpendicular magnetic
+anisotropy are characterized. We find that though Ta has a significant spin
+Hall effect, the DL-SOT efficiencies are small in systems with the Ta/Py
+interface compared to that obtained from the control sample with the
+traditional Ta/CoFeB interface. Our results indicate that the spin transparency
+for the Ta/Py interface is much less than that for the Ta/CoFeB interface,
+which might be related to the variation of spin mixing conductance for
+different interfaces.",1811.05164v1
+2018-10-31,Crack Path Selection in Orientationally Ordered Composites,"While cracks in isotropic homogeneous materials propagate straight,
+perpendicularly to the tensile axis, cracks in natural and synthetic composites
+deflect from a straight path, often increasing the toughness of the material.
+Here we combine experiments and simulations to identify materials properties
+that predict whether cracks propagate straight or kink on a macroscale larger
+than the composite microstructure. Those properties include the anisotropy of
+the fracture energy, which we vary several folds by increasing the volume
+fraction of orientationally ordered alumina platelets inside a polymer matrix,
+and a microstructure-dependent process zone size that is found to modulate the
+additional stabilizing or destabilizing effect of the non-singular stress
+acting parallel to the crack. Those properties predict the existence of an
+anisotropy threshold for crack kinking and explain the surprisingly strong
+dependence of this threshold on sample geometry and load distribution.",1811.05891v4
+2018-11-15,Firehose instabilities triggered by the solar wind suprathermal electrons,"In collision-poor plasmas from space, e.g., solar wind, terrestrial
+magnetospheres, kinetic instabilities are expected to play a major role in
+constraining the temperature anisotropy of plasma particles, but a definitive
+answer can be given only after ascertaining their properties in these
+environments. Present study describes the full spectrum of electron firehose
+instabilities in the presence of suprathermal electron populations which are
+ubiquitous in space plasmas. Suprathermal electrons stimulate both the periodic
+and aperiodic branches, remarkable being the effects shown by the aperiodic
+mode propagating obliquely to the ambient magnetic field which markedly exceeds
+the growth rates of the parallel (periodic) branch reported recently in Lazar
+et al., (2017a, MNRAS 464, 564). Derived exclusively in terms of the plasma
+parameters, the anisotropy thresholds of this instability are also lowered in
+the presence of suprathermal electrons, predicting an enhanced effectiveness in
+the solar wind conditions. These results may also be relevant in various other
+astrophysical contexts where the firehose instabilities involve, e.g., solar
+flares, sites of magnetic field reconnection, accretion flows or plasma jets
+leading to shocks and co-rotating interactions in heliosphere, interstellar
+medium and galaxy clusters.",1811.06320v1
+2018-11-22,"E-by-e jet suppression, anisotropy, medium response and hard-soft tomography","The Linear Boltzmann Transport (LBT) model for jet propagation and
+interaction in quark-gluon plasma (QGP) has been used to study jet quenching in
+high-energy heavy-lion collisions. The suppression of single inclusive jet
+production, medium modification of $\gamma$-jet correlation, jet profiles and
+fragmentation functions as observed in experiments at Large Hadron Collider
+(LHC) can be described well by LBT in which jet-induced medium response is
+shown to play an essential role. In event-by-event simulations of jet quenching
+within LBT, jet azimuthal anisotropies are found to correlate linearly with the
+anisotropic flows of bulk hadrons from the underlying hydrodynamic events.",1811.08975v2
+2018-11-22,BRDF Estimation of Complex Materials with Nested Learning,"The estimation of the optical properties of a material from RGB-images is an
+important but extremely ill-posed problem in Computer Graphics. While recent
+works have successfully approached this problem even from just a single
+photograph, significant simplifications of the material model are assumed,
+limiting the usability of such methods. The detection of complex material
+properties such as anisotropy or Fresnel effect remains an unsolved challenge.
+We propose a novel method that predicts the model parameters of an
+artist-friendly, physically-based BRDF, from only two low-resolution shots of
+the material. Thanks to a novel combination of deep neural networks in a nested
+architecture, we are able to handle the ambiguities given by the
+non-orthogonality and non-convexity of the parameter space. To train the
+network, we generate a novel dataset of physically-based synthetic images. We
+prove that our model can recover new properties like anisotropy, index of
+refraction and a second reflectance color, for materials that have tinted
+specular reflections or whose albedo changes at glancing angles.",1811.09131v1
+2018-11-27,Layer dependent antiferromagnetism in the Sr4Ru3O10 ruthenate at the metamagnetic-like transition,"We have investigated the metamagnetic-like transition in the triple layer
+ruthenate Sr4Ru3O10 by means of neutron diffraction from single crystals. The
+magnetic structure of the compound appears to be determined in a complex way by
+the two substructures of inequivalent ruthenium ions. At Tc=105K the system has
+a sharp transition into a ferromagnetic state along the c-axis which is driven
+by the ruthenium atoms in the central octahedra of the triple layers whereas
+the substructure of the outer ruthenium atoms tend to align in the ab plane
+achieving an antiferromagnetic order at the metamagnetic transition T*~50K.
+Below T* the strong anisotropy along c prevails, the outer ruthenium tend to
+align along the c-axis and the in-plane antiferromagnetic order disappears.
+This finding confirms the delicate balance between antiferro and ferromagnetic
+couplings in the (Sr,Ca)n+1RunO3n+1 family of compounds, and proves the layer
+dependence of the magnetic anisotropy in Sr4Ru3O10.",1811.11065v3
+2018-11-29,Magneto-immutable turbulence in weakly collisional plasmas,"We propose that pressure anisotropy causes weakly collisional turbulent
+plasmas to self-organize so as to resist changes in magnetic-field strength. We
+term this effect ""magneto-immutability"" by analogy with incompressibility
+(resistance to changes in pressure). The effect is important when the pressure
+anisotropy becomes comparable to the magnetic pressure, suggesting that in
+collisionless, weakly magnetized (high-$\beta$) plasmas its dynamical relevance
+is similar to that of incompressibility. Simulations of magnetized turbulence
+using the weakly collisional Braginskii model show that magneto-immutable
+turbulence is surprisingly similar, in most statistical measures, to critically
+balanced MHD turbulence. However, in order to minimize magnetic-field
+variation, the flow direction becomes more constrained than in MHD, and the
+turbulence is more strongly dominated by magnetic energy (a nonzero ""residual
+energy""). These effects represent key differences between pressure-anisotropic
+and fluid turbulence, and should be observable in the $\beta\gtrsim1$ turbulent
+solar wind.",1811.12421v2
+2018-12-03,Magnetic excitations in the quasi-2D ferromagnet Fe3-xGeTe2 measured with inelastic neutron scattering,"Fe3-xGeTe2 is an itinerant ferromagnet composed of two-dimensional layers
+weakly connected by van der Waals bonding that shows a variety of intriguing
+phenomena. Inelastic neutron scattering measurements on bulk single crystals of
+Fe2.75GeTe2 were performed to quantify the magnetic exchange interaction
+energies and anisotropy. The observed inelastic excitations are indicative of
+dominant in-plane correlations with negligible magnetic interactions between
+the layers. A spin-gap of 3.9 meV is observed allowing a measure of the
+magnetic anisotropy. As the excitations disperse to their maximum energy (~65
+meV) they become highly damped, reflective of both the magnetic site occupancy
+reduction of 25{\%} on one Fe sublattice and the itinerant interactions. A
+minimal model is employed to describe the excitation spectra and extract
+nearest neighbor magnetic exchange interaction values. The temperature
+evolution of the excitations are probed and correlations shown to persist above
+Tc, indicative of low dimensional magnetism.",1812.00519v1
+2018-12-04,"Anisotropic thermal Sunyaev-Zel'dovich effect and the possibility of an independent measurement of the CMB dipole, quadrupole and octupole","We consider the effect of the cosmic microwave background (CMB) frequency
+spectral distortions arising due to the Compton scattering of the anisotropic
+radiation on Sunyaev-Zel'dovich (SZ) clusters. We derive the correction to the
+thermal SZ effect due to the presence of multipoles with $\ell=1,2,3$ in the
+anisotropy of the CMB radiation. We show that this effect gives us an
+opportunity for an independent evaluation of the CMB dipole, quadrupole and
+octupole angular anisotropy in our location using distorted signal from the
+nearby galaxy clusters and to distinguish between the Sachs-Wolfe (SW) and the
+Integrated Sachs-Wolfe (ISW) effects by combining such signals from distant and
+nearby clusters. The future space mission 'Millimetron' will have unprecedented
+sensitivity, which will make it possible to observe the spectral distortion we
+are considering.",1812.01330v2
+2018-12-05,Voltage-induced strain clocking of nanomagnets with perpendicular magnetic anisotropies,"Nanomagnetic logic (NML) has attracted attention during the last two decades
+due to its promise of high energy efficiency combined with non-volatility. Data
+transmission in NML relies on Bennett clocking through dipole interaction
+between neighboring nanomagnetic bits. This paper uses a fully coupled finite
+element model to simulate Bennett clocking based on strain-mediated
+multiferroic system for Ni, CoFeB and Terfenol-D with perpendicular magnetic
+anisotropies. Simulation results demonstrate that Terfenol-D system has the
+highest energy efficiency, which is 2 orders of magnitude more efficient than
+Ni and CoFeB. However, the high efficiency is associated with switching
+incoherency due to its large magnetostriction coefficient. It is also suggested
+that the CoFeB clocking system is slower and has lower bit-density than in Ni
+or Terfenol-D systems due to its large dipole coupling. Moreover, we
+demonstrate that the precessional perpendicular switching and the Bennett
+clocking can be achieved using the same strain-mediated multiferroic
+architecture with different voltage pulsing. This study opens new possibilities
+to an all-spin in-memory computing system.",1812.02268v1
+2018-12-06,Charge and Spin Transport Anisotropy in Nanopatterned Graphene,"Anisotropic electronic transport is a possible route towards nanoscale
+circuitry design, particularly in two-dimensional materials. Proposals to
+introduce such a feature in patterned graphene have to date relied on
+large-scale structural inhomogeneities. Here we theoretically explore how a
+random, yet homogeneous, distribution of zigzag-edged triangular perforations
+can generate spatial anisotropies in both charge and spin transport.
+Anisotropic electronic transport is found to persist under considerable
+disordering of the perforation edges, suggesting its viability under realistic
+experimental conditions. Furthermore, controlling the relative orientation of
+perforations enables spin filtering of the transmitted electrons, resulting in
+a half-metallic anisotropic transport regime. Our findings point towards a
+co-integration of charge and spin control in a two-dimensional platform of
+relevance for nanocircuit design. We further highlight how geometrical effects
+allow finite samples to display finite transverse resistances, reminiscent of
+Spin Hall effects, in the absence of any bulk fingerprints of such mechanisms,
+and explore the underlying symmetries behind this behaviour.",1812.02429v1
+2018-12-06,Kinetic theory of spin diffusion and superdiffusion in XXZ spin chains,"We address the nature of spin transport in the integrable XXZ spin chain,
+focusing on the isotropic Heisenberg limit. We calculate the diffusion constant
+using a kinetic picture based on generalized hydrodynamics combined with
+Gaussian fluctuations: we find that it diverges, and show that a
+self-consistent treatment of this divergence gives superdiffusion, with an
+effective time-dependent diffusion constant that scales as $D(t) \sim t^{1/3}$.
+This exponent had previously been observed in large-scale numerical
+simulations, but had not been theoretically explained. We briefly discuss XXZ
+models with easy-axis anisotropy $\Delta > 1$. Our method gives closed-form
+expressions for the diffusion constant $D$ in the infinite-temperature limit
+for all $\Delta > 1$. We find that $D$ saturates at large anisotropy, and
+diverges as the Heisenberg limit is approached, as $D \sim (\Delta -
+1)^{-1/2}$.",1812.02701v2
+2018-12-10,Topologically nontrivial magnonic solitons,"The intrinsic non-linearities of the spin dynamics in condensed matter
+systems give rise to a rich phenomenology that can be strongly affected by
+topology. Here we study formation of magnonic solitons in the topologically
+nontrivial bandgap of a spin lattice realization of the Haldane model, in both
+static and dynamic (Floquet) regimes. We consider nonlinearities caused by
+magnetic crystalline anisotropy and magnon-magnon interactions. We find soliton
+formation power thresholds as a function of anisotropy coefficient and
+interaction strength. We predict different classes of topological solitons for
+the same topological class of the underlying lattice and explain it in terms of
+a transition from a topologically nontrivial mass to a trivial one. Our
+findings imply that a soliton can phase-separate, containing boundaries between
+topologically trivial and non-trivial phases, which is associated with a
+vanishing spin wave gap.",1812.03738v2
+2018-12-10,Collectivity in pp from resummed interference effects?,"Azimuthal asymmetries $v_n$ in the soft transverse momentum spectra of
+hadronic collisions can result as a consequence of quantum interference and
+color flow which translates spatial anisotropies into momentum anisotropies via
+multipole radiation patterns. Here, we analyze to what extent these effects
+result in signal strengths $v_n\lbrace 2s\rbrace$ that can persist in higher
+order $(2s)$ cumulants. In a simple model of soft multi-particle production
+with quantum interference effects in which $m$ particles are emitted from $N$
+sources and in which interference contributions appear naturally ordered in
+inverse powers of the adjoint color trace, $1/(N_c^2-1)$, we provide the first
+resummed calculation of all powers of $m^2/(N_c^2-1)$. This allows one to
+determine all higher order flow cumulants $v_n\lbrace 2s\rbrace$ with the same
+parametric accuracy. For a phenomenologically relevant range of $N$ sources
+emitting $m$ particles, we find that the even flow coefficients $v_n\lbrace
+2s\rbrace$ decrease very mildly with increasing cumulants. This provides a
+proof of principle that non-vanishing higher order cumulants $v_n\lbrace
+2s\rbrace$ can persist in systems that exhibit neither final state interactions
+nor phenomena related to high (saturated) initial parton densities.",1812.04113v1
+2018-12-17,Spin chirality fluctuation in two-dimensional ferromagnets with perpendicular anisotropy,"Non-coplanar spin textures with scalar spin chirality can generate effective
+magnetic field that deflects the motion of charge carriers, resulting in
+topological Hall effect (THE), a powerful probe of the ground state and
+low-energy excitations of correlated systems. However, spin chirality
+fluctuation in two-dimensional ferromagnets with perpendicular anisotropy has
+not been considered in prior studies. Herein, we report direct evidence of
+universal spin chirality fluctuation by probing the THE above the transition
+temperatures in two different ferromagnetic ultra-thin films, SrRuO$_3$ and V
+doped Sb$_2$Te$_3$. The temperature, magnetic field, thickness, and carrier
+type dependences of the THE signal, along with our Monte-Carlo simulations,
+unambiguously demonstrate that the spin chirality fluctuation is a universal
+phenomenon in two-dimensional Ising ferromagnets. Our discovery opens a new
+paradigm of exploring the spin chirality with topological Hall transport in
+two-dimensional magnets and beyond",1812.07005v2
+2018-12-18,Tilted Klein tunneling across atomically sharp interfaces,"Despite many similarities between electronics and optics, the hopping of the
+electron on a discrete atomic lattice gives rise to energy band nonparabolicity
+and anisotropy. The crucial influences of this effect on material properties
+and its incorporation into the continuum model have received widespread
+attention in the past half century. Here we predict the existence of a
+different effect due to the hopping of the electron across an atomically sharp
+interface. For a general lattice, its influence on transport could be equally
+important as the energy band nonparabolicity/anisotropy, but cannot be
+incorporated into the continuum model. On the honeycomb lattice of graphene, it
+leads to the breakdown of the conventional Klein tunneling -- one of the exotic
+phenomena of relativistic particles -- and the onset of tilted Klein tunneling.
+This works identifies a unique feature of the discrete atomic lattice for
+transport, which is relevant for ballistic electronic devices at high carrier
+densities.",1812.07196v2
+2018-12-19,Surface monolayers and magnetic field,"We study theoretically the magnetic properties of the surface monolayers with
+the antiferromagnetic (AF) and ferromagnetic (FM) exchange interactions where
+the Dzyaloshinskii-Moriya interaction (DMI) is a result of the mirror symmetry
+breaking. To study the DMI helices in magnetic field a method is proposed. In
+zero field the DMI gives rise a cycloid in both AF and FM cases. The cycloid
+orientation is determined by the DMI induced in-plane anisotropy with the
+symmetry of the layer lattice. As a result we have one, two and three chiral
+domains in the rectangular, square and triangular lattices respectively. The
+magnetic structure of the $M n/W(1 1 0)$ monolayer is explained. The
+out-of-plane anisotropy may restore a collinear magnetic order. The chiral
+domains are rotated by the in-plane field. In some field directions the spin
+flops are predicted. In the out-of-plane field the chirality follows the field
+direction. The length of the cycloid wave-vector decreases. In the
+perpendicular field there is the spin flop to the corresponding collinear
+state. A possibility of the layer electric polarization is discussed.",1812.07892v1
+2019-01-07,"Heavily Fe-doped n-type ferromagnetic semiconductor (In,Fe)Sb with high Curie temperature and large magnetic anisotropy","We present high-temperature ferromagnetism and large magnetic anisotropy in
+heavily Fe-doped n-type ferromagnetic semiconductor (In1-x,Fex)Sb (x = 20 -
+35%) thin films grown by low-temperature molecular beam epitaxy. The
+(In1-x,Fex)Sb thin films with x = 20 - 35% maintain the zinc-blende crystal and
+band structure with single-phase ferromagnetism. The Curie temperature (TC) of
+(In1-x,Fex)Sb reaches 390 K at x = 35%, which is significantly higher than room
+temperature and the highest value so far reported in III-V based ferromagnetic
+semiconductors. Moreover, large coercive force (HC = 160 Oe) and large remanent
+magnetization (Mr/MS = 71%) have been observed for a (In1-x,Fex)Sb thin film
+with x = 35%. Our results indicate that the n-type ferromagnetic semiconductor
+(In1-x,Fex)Sb is very promising for spintronics devices operating at room
+temperature.",1901.01996v1
+2019-01-09,Six-loop $\varepsilon$ expansion study of three-dimensional $n$-vector model with cubic anisotropy,"The six-loop expansions of the renormalization-group functions of $\varphi^4$
+$n$-vector model with cubic anisotropy are calculated within the minimal
+subtraction (MS) scheme in $4 - \varepsilon$ dimensions. The $\varepsilon$
+expansions for the cubic fixed point coordinates, critical exponents
+corresponding to the cubic universality class and marginal order parameter
+dimensionality $n_c$ separating different regimes of critical behavior are
+presented. Since the $\varepsilon$ expansions are divergent numerical estimates
+of the quantities of interest are obtained employing proper resummation
+techniques. The numbers found are compared with their counterparts obtained
+earlier within various field-theoretical approaches and by lattice
+calculations. In particular, our analysis of $n_c$ strengthens the existing
+arguments in favor of stability of the cubic fixed point in the physical case
+$n = 3$.",1901.02754v3
+2019-01-17,"Influences of interfacial oxidization on surface magnetic energy, magnetic damping and spin-orbit-torques in Pt / ferromagnet / capping structures","We investigate the effect of capping layer (CAP) on the interfacial magnetic
+anisotropy energy density (K_S), magnetic damping ({\alpha}), and spin-orbit
+torques (SOTs) in heavy-metal (Pt) / ferromagnet (Co or Py) / CAP (MgO/Ta,
+HfOx, or TaN). At room temperature (RT) the CAP materials influence the
+effective magnitude of K_S, which is associated with a formation of interfacial
+magnetic oxides. The dynamical dissipation parameters of Co are considerably
+influenced by the CAP (especially MgO) while those of Py are not. This is
+possibly due to an extra magnetic damping via spin-pumping process across the
+Co/CoO interface and incoherent magnon generation (spin fluctuation) in the
+interfacial CoO. It is also observed that both anti-damping and field-like SOT
+efficiencies vary marginally with the CAP in the thickness ranges we examined.
+Our results reveal the crucial role of interfacial oxides on the perpendicular
+magnetic anisotropy, magnetic damping, and SOTs.",1901.05777v1
+2019-01-17,Waveguide propagation of light in polymer porous films filled with nematic liquid crystals,"We theoretically analyze the waveguide regime of light propagation in a
+cylindrical pore of a polymer matrix filled with liquid crystals assuming that
+the effective radial optical anisotropy is biaxial. From numerical analysis of
+the dispersion relations, the waveguide modes are found to be sensitive to the
+field-induced changes of the anisotropy. The electro-optic properties of the
+polymer porous polyethylene terephthalate (PET) films filled with the nematic
+liquid crystal 5CB are studied experimentally and the experimental results are
+compared with the results of the theoretical investigation.",1901.05782v1
+2019-01-21,Built-in Fluorescence Anisotropy: an in vivo Imaging Probe for bis-Retinoid Products in Retina,"Non-degradable fluorophores that accumulate as Lipofuscin in retinal pigment
+epithelium (RPE) cells has been a major source of intrinsic biomarker for
+quantifying the progression of several diseases, including age-related macular
+degeneration, Stargardt disease and, more. Recent progression in quantifying
+these diseases is entertained mostly by a few noninvasive imaging techniques,
+relied either on the life-time of the retinoid-fluorophores or, their linear
+and, non-linear absorption cross-sections. Apart from these intrinsic
+properties, a native, excited state dipole-dipole interaction mediated typical
+spectroscopic phenomenon that is excitation dependent emission-wavelength
+shifting is observed from these bis-retinoid fluorophores. Here, we emphasize
+the spectroscopic origin of this phenomenon and exploit one of its
+associated-properties, that is built-in fluorescence anisotropy as a
+noninvasive, in vivo imaging probe for bis-retinoid products in mouse eyes.",1901.08104v1
+2019-01-28,Sedimentation of a suspension of rods: Monte Carlo simulation of a continuous two-dimensional problem,"The sedimentation of a two dimensional suspension containing rods was studied
+by means of kinetic Monte Carlo (MC) simulations. An off-lattice model with
+continuous positional and orientational degrees of freedom was considered. The
+initial state before sedimentation was produced using a model of random
+sequential adsorption. During such sedimentation, the rods undergo
+translational and rotational Brownian motions. The MC simulations were run at
+different initial number densities (the numbers of rods per unit area),
+$\rho_i$, and sedimentation rates, $u$. For sediment films, the spatial
+distributions of the rods, the order parameters and the electrical
+conductivities were examined. Different types of sedimentation-driven
+self-assembly and anisotropy of the electrical conductivity were revealed
+inside the sediment films. This anisotropy can be finely regulated by changes
+in the values of $\rho_i$ and $u$.",1901.09516v2
+2018-12-12,Substrate induced magnetic anisotropies and magneto-optical response in YIG nanosized epitaxial films on NdGG(111),"Nanosized Y3Fe5O12 epitaxial films have been grown on Nd3Ga5O12 substrates
+using laser molecular beam epitaxy method. Magneto-optical polar Kerr effect,
+ferromagnetic resonance and spin wave propagation measurements show that the
+stress-related anisotropy field has an opposite sign, compared to that in the
+YIG/GGG systems. This leads to a considerable decrease of the effective
+magnetization that opens a perspective to get YIG films with perpendicular
+magnetization for utilizing forward volume spin waves. Longitudinal
+magnetooptical Kerr effect magnetometry reveals a large contribution of
+quadratic in magnetization terms into dielectric permittivity tensor at optical
+frequencies. This effect strongly increases with temperature decrease and is
+explained by magnetization of the interface Nd3+ ions that are exchange coupled
+to the Fe3+ ions.",1901.10800v1
+2019-01-30,Van Hove scenario of anisotropic transport in a two-dimensional spin-orbit coupled electron gas in an in-plane magnetic field,"We study electronic transport in two-dimensional spin-orbit coupled electron
+gas subjected to an in-plane magnetic field. The interplay of the spin-orbit
+interaction and the magnetic field leads to the Van Hove singularity of the
+density of states and strong anisotropy of Fermi contours. We develop a method
+that allows one to exactly calculate the nonequilibrium distribution function
+for these conditions within the framework of the semiclassical Boltzmann
+equation without using the scattering time approximation. The method is applied
+to calculate the conductivity tensor and the tensor of spin polarization
+induced by the electric field (Aronov-Lyanda-Geller-Edelstein effect). It is
+found that both the conductivity and the spin polarization have a sharp
+singularity as functions of the Fermi level or magnetic field, which occurs
+when the Fermi level passes through the Van Hove singularity. In addition, the
+transport anisotropy dramatically changes near the singularity.",1901.10823v1
+2019-01-31,The Interplay of the Solar Wind Core and Suprathermal Electrons: A Quasilinear Approach for Firehose Instability,"In the solar wind an equipartition of kinetic energy densities can be easily
+established between thermal and suprathermal electrons and the instability
+conditions are markedly altered by the interplay of these two populations. The
+new thresholds derived here for the periodic branch of firehose instability
+shape the limits of temperature anisotropy reported by the observations for
+both electron populations. This instability constraint is particularly
+important for the suprathermal electrons which, by comparison to thermal
+populations, are even less controlled by the particle-particle collisions. An
+extended quasilinear approach of this instability confirms predictions from
+linear theory and unveil the mutual effects of thermal and suprathermal
+electrons in the relaxation of their temperature anisotropies and the
+saturation of growing fluctuations.",1901.11406v1
+2019-02-06,Barut-Girardello coherent states for anisotropic 2D-Dirac materials,"We construct the Barut-Girardello coherent states for charge carriers in
+anisotropic 2D-Dirac materials immersed in a constant homogeneous magnetic
+field which is orthogonal to the sample surface. For that purpose, we solve the
+anisotropic Dirac equation and identify the appropriate arising and lowering
+operators. Working in a Landau-like gauge, we explicitly construct nonlinear
+coherent states as eigenstates of a generalized annihilation operator with
+complex eigenvalues which depends on an arbitrary function $f$ of the number
+operator. In order to describe the anisotropy effects on these states, we
+obtain the Heisenberg uncertainty relation, the probability density, mean
+energy value and occupation number distribution for three different functions
+$f$. For the case in which the anisotropy is caused by uniaxial strain, we
+obtain that when a stress is applied along the $x$-axis of the material
+surface, the probability density for the nonlinear coherent states is smaller
+compared to when the material is stressed along the orthogonal axis.",1902.01995v3
+2019-02-07,Nanoscale optical and structural characterisation of silk,"Background: Nanoscale composition of silk defining its unique properties via
+a hierarchical structural anisotropy has to be analysed at the highest spatial
+resolution of tens-of-nanometers corresponding to the size of fibrils made of
+b-sheets, which are the crystalline building blocks of silk. Results: Nanoscale
+optical and structural properties of silk have been measured from 100-nm thick
+longitudinal slices of silk fibers with ~10 nm resolution, the highest so far.
+Optical sub-wavelength resolution in hyperspectral mapping of absorbance and
+molecular orientation were carried out for comparison at IR wavelengths 2-10
+micrometers using synchrotron radiation. Conclusion: Reliable distinction of
+transmission changes by only 1-2% due to anisotropy of amide bands was obtained
+from nano-thin slices of silk.",1902.02688v1
+2019-02-08,A Microwave Oscillator Based on a Single Straintronic Magneto-tunneling Junction,"There is growing interest in exploring nanomagnetic devices as potential
+replacements for electronic devices (e.g. transistors) in digital switching
+circuits and systems. A special class of nanomagnetic devices are switched with
+electrically generated mechanical strain leading to electrical control of
+magnetism. Straintronic magneto-tunneling junctions (s-MTJ) belong to this
+category. Their soft layers are composed of two-phase multiferroics comprising
+a magnetostrictive layer elastically coupled to a piezoelectric layer. Here, we
+show that a single straintronic magneto-tunneling junction with a passive
+resistor can act as a microwave oscillator whose traditional implementation
+would have required microwave operational amplifiers, capacitors and resistors.
+This reduces device footprint and cost, while improving device reliability.
+This is an analog application of magnetic devices where magnetic interactions
+(interaction between the shape anisotropy, strain anisotropy, dipolar coupling
+field and spin transfer torque in the soft layer of the s-MTJ) are exploited to
+implement an oscillator with reduced footprint.",1902.03307v2
+2019-02-13,Interacting non-Hermitian ultracold atoms in a harmonic trap: Two-body exact solution and high-order exceptional point,"We study interacting ultracold atoms in a three-dimensional (3D) harmonic
+trap with spin-selective dissipations, which can be effectively described by
+non-Hermitian parity-time ($\mathcal{PT}$) symmetric Hamiltonians. By solving
+the non-Hermitian two-body problem of spin-1/2 (spin-1) bosons in a 3D harmonic
+trap exactly, we find that the system can exhibit third-order (fifth-order)
+exceptional point (EP) with ultra-sensitive cube-root (fifth-root) spectral
+response due to interaction anisotropies in spin channels. We also present the
+general principle for the creation of high-order EPs and their spectral
+sensitivities with arbitrary particle number $N$ and arbitrary spin $s$.
+Generally, with spin-independent interactions, the EP order of bosons can be as
+high as $2Ns+1$, and the spectral response around EP can be as sensitive as
+$\sim \epsilon^{1/(2ks+1)}$ under a $k$-body interaction anisotropy. Moreover,
+we propose to detect the ultra-sensitive spectral response through the
+probability dynamics of certain state. These results suggest a convenient route
+towards more powerful sensor devices in spinor cold atomic systems.",1902.04769v3
+2019-02-13,Numerical anisotropy study of a class of compact schemes,"We study the numerical anisotropy existent in compact difference schemes as
+applied to hyperbolic partial differential equations, and propose an approach
+to reduce this error and to improve the stability restrictions based on a
+previous analysis applied to explicit schemes. A prefactorization of compact
+schemes is applied to avoid the inversion of a large matrix when calculating
+the derivatives at the next time level, and a predictor-corrector time marching
+scheme is used to update the solution in time. A reduction of the isotropy
+error is attained for large wave numbers and, most notably, the stability
+restrictions associated with MacCormack time marching schemes are considerably
+improved. Compared to conventional compact schemes of similar order of
+accuracy, the multidimensional schemes employ larger stencils which would
+presumably demand more processing time, but we show that the new stability
+restrictions render the multidimensional schemes to be in fact more efficient,
+while maintaining the same dispersion and dissipation characteristics of the
+one dimensional schemes.",1902.05042v1
+2019-02-21,Spin-orbit coupling and spin relaxation in phosphorene: Intrinsic versus extrinsic effects,"First-principles calculations of the essential spin-orbit and spin relaxation
+properties of phosphorene are performed. Intrinsic spin-orbit coupling induces
+spin mixing with the probability of $b^2 \approx 10^{-4}$, exhibiting a large
+anisotropy, following the anisotropic crystalline structure of phosphorene. For
+realistic values of the momentum relaxation times, the intrinsic
+(Elliott--Yafet) spin relaxation times are hundreds of picoseconds to
+nanoseconds. Applying a transverse electric field (simulating gating and
+substrates) generates extrinsic $C_{2v}$ symmetric spin-orbit fields in
+phosphorene, which activate the D'yakonov--Perel' mechanism for spin
+relaxation. It is shown that this extrinsic spin relaxation also has a strong
+anisotropy, and can dominate over the Elliott-Yafet one for strong enough
+electric fields. Phosphorene on substrates can thus exhibit an interesting
+interplay of both spin relaxation mechanisms, whose individual roles could be
+deciphered using our results.",1902.07957v1
+2019-02-22,Temperature-dependent Saturation of Weibel-type Instabilities in Counter-streaming Plasmas,"We present the first 2X2V continuum Vlasov-Maxwell simulations of
+interpenetrating, unmagnetized plasmas to study the competition between
+two-stream, Oblique, and filamentation modes in the weakly relativistic regime.
+We find that after nonlinear saturation of the fastest-growing two-stream and
+Oblique modes, the effective temperature anisotropy, which drives current
+filament formation via the secular Weibel instability, has a strong dependence
+on the internal temperature of the counter-streaming plasmas. The effective
+temperature anisotropy is significantly more reduced in colder than in hotter
+plasmas, leading to orders of magnitude lower magnetization for colder plasmas.
+A strong dependence of the energy conversion efficiency of Weibel-type
+instabilities on internal beam temperature has implications for determining
+their contribution to the observed magnetization of many astrophysical and
+laboratory plasmas.",1902.08672v1
+2019-02-26,A new class of nonreciprocal spin waves on the edges of 2D antiferromagnetic honeycomb nanoribbons,"Antiferromagnetic two-dimensional (2D) materials are currently under
+intensive theoretical and experimental investigations in view of their
+potential applications in antiferromagnet-based magnonic and spintronic
+devices. Recent experimental studies revealed the importance of magnetic
+anisotropy and Dzyaloshinskii-Moriya interactions (DMI) on the ordered ground
+state and the magnetic excitations in these materials. Here we present a robust
+classical field theory approach to analyze the effect of magnetic anisotropy
+and Dzyaloshinskii-Moriya interactions (DMI) on the edge and bulk spin waves in
+2D antiferromagnetic nanoribbons. We predict the existence of a new class of
+nonreciprocal edge spin waves characterized by opposite polarizations in
+opposite directions. These novel edge spin waves are induced by the DMI and are
+fundamentally different from conventional nonreciprocal spin waves for which
+the polarization is independent of the propagation direction. Aside this
+breakthrough in the field of antiferromagnetic spin waves, the study further
+analysis the effect of the edges structure on the magnetic excitations. In
+particular, we show that anisotropic bearded edges nanoribbons act as magnetic
+topological insulators with exceptionally interesting potentials for
+applications in magnonics.",1902.09704v3
+2019-02-27,Cosmic ray acceleration to ultrahigh energy in radio galaxies,"The origin of ultrahigh energy cosmic rays (UHECRs) is an open question. In
+this proceeding, we first review the general physical requirements that a
+source must meet for acceleration to 10-100 EeV, including the consideration
+that the shock is not highly relativistic. We show that shocks in the backflows
+of radio galaxies can meet these requirements. We discuss a model in which
+giant-lobed radio galaxies such as Centaurus A and Fornax A act as
+slowly-leaking UHECR reservoirs, with the UHECRs being accelerated during a
+more powerful past episode. We also show that Centaurus A, Fornax A and other
+radio galaxies may explain the observed anisotropies in data from the Pierre
+Auger Observatory, before examining some of the difficulties in associating
+UHECR anisotropies with astrophysical sources.",1902.10382v1
+2019-03-01,Modeling the non-trivial behavior of anisotropic beams: a simple Timoshenko beam with enhanced stress recovery and constitutive relations,"This paper analyzes the non-trivial influence of the material anisotropy on
+the structural behavior of an anisotropic multilayer planar beam. Indeed,
+analytical results available in literature are limited to homogeneous beams and
+several aspects has not been addressed yet, impeding an in-depth understanding
+of the mechanical response of anisotropic structural elements. This paper
+proposes an effective recovery of stress distribution and an energetically
+consistent evaluation of constitutive relations to be used within a planar
+Timoshenko beam model. The resulting structural-analysis tool highlights the
+following peculiarities of anisotropic beams: (i) the axial stress explicitly
+depends on transversal internal force, which can weigh up to 30% on the maximal
+magnitude of axial stress, and (ii) the anisotropy influences the beam
+displacements more than standard shear deformation and even for extremely
+slender beams. A rigorous comparison with analytical and accurate 2D Finite
+Element solutions confirms the accuracy of the proposed approach that leads to
+errors exceptionally greater than 5%.",1903.00200v1
+2019-03-03,Dynamical mode coupling and coherence in spin Hall nano-oscillator with perpendicular magnetic anisotropy,"We experimentally study the dynamical modes excited by spin current in Spin
+Hall nano-oscillators based on the Pt/[Co/Ni] multilayers with perpendicular
+magnetic anisotropy. Both propagating spin wave and localized solitonic modes
+of the oscillation are achieved and controlled by varying the applied magnetic
+field and current. At room temperature, the generation linewidth broadening
+associated with mode hopping was observed at currents close to the transition
+between different modes and in the mode coexistence regimes. The mode hopping
+was suppressed at cryogenic temperatures, confirming that the coupling between
+modes is mediated by thermal magnons. We also demonstrate that coherent
+single-mode oscillations with linewidth of 5 MHz can be achieved without
+applying external magnetic field. Our results provide insight into the
+mechanisms controlling the dynamical coherence in nanomagnetic oscillators, and
+guidance for optimizing their applications in spin wave-based electronics.",1903.00822v1
+2019-03-03,Goos-Hanchen Shift of a Spin-Wave Beam at the Interface Between Two Ferromagnets,"Spin waves are promising information carriers which can be used in modern
+magnonic devices, characterized by higher performance and lower energy
+consumption than presently used electronic circuits. However, before practical
+application of spin waves, the efficient control over spin wave amplitude and
+phase needs to be developed. We analyze analytically reflection and refraction
+of the spin waves at the interface between two ferromagnetic materials. In the
+model we consider the system consisting of two semi-infinite ferromagnetic
+media, separated by the ultra-narrow interface region with the magnetic
+anisotropy. We have found the Goos-Hanchen shift for spin waves in transmission
+and reflection, and performed detailed investigations of its dependence on the
+anisotropy at the interface and materials surrounding the interface. We have
+demonstrated possibility of obtaining Goos-Hanchen shift of several wavelengths
+in reflection for realistic material parameters. That proves the possibility
+for change of the spin waves phase in ferromagnetic materials at subwavelength
+distances, which can be regarded as a metasurface for magnonics.",1903.00861v1
+2019-03-07,Effect of in-medium mass-shift on transverse-momentum spectrum and elliptic anisotropy of $φ$ meson,"We study the effect of in-medium mass-shift on transverse-momentum spectrum
+and elliptic anisotropy of $\phi$ meson. It is found that the mass-shift
+enhances the $\phi$ yields and suppresses the elliptic flow $v_2$ in large
+momentum region, and the effects increase with the increasing mass-shift. The
+effects are various for different sources and decrease with the increasing
+expanding velocity. We further study the effects for parts of all $\phi$ meson
+with mass-shift, and the effects decrease with the decreasing probability of
+$\phi$ meson with mass-shift. Since the different mass-shift lead to different
+transverse-momentum spectrum and $v_2$, our study may provide a way to restrict
+the ranges of in-medium mass-shift of $\phi$ meson in high-energy heavy-ion
+collisions.",1903.02997v3
+2019-03-08,Intra- and inter-orbital correlated electron spin dynamics in $\rm Sr_2 Ir O_4$: spin-wave gap and spin-orbit exciton,"Transformation of Coulomb interaction terms to the pseudo-orbital basis
+constituted by $J=1/2$ and $3/2$ states arising from spin-orbit coupling
+provides a versatile tool. This formalism is applied to investigate magnetic
+anisotropy effects on low-energy spin-wave excitations as well as high-energy
+spin-orbit exciton modes in $\rm Sr_2 Ir O_4$. The Hund's coupling term
+explictly yields easy-plane anisotropy, resulting in gapless (in-plane) and
+gapped (out-of-plane) modes, in agreement with recent resonant inelastic x-ray
+scattering (RIXS) measurements. The collective mode of inter-orbital,
+spin-flip, particle-hole excitations with appropriate interaction strengths and
+renormalized spin-orbit gap yields two well-defined propagating spin-orbit
+exciton modes, with energy scale and dispersion in good agreement with RIXS
+studies.",1903.03360v1
+2019-03-11,Anisotropy Control in Photoelectron Spectra: A Coherent Two-Pulse Interference Strategy,"Coherence among rotational ion channels during photoionization is exploited
+to control the anisotropy of the resulting photoelectron angular distributions
+at specific photoelectron energies. The strategy refers to a robust and single
+parameter control using two ultra-short light pulses delayed in time. The first
+pulse prepares a superposition of a few ion rotational states, whereas the
+second pulse serves as a probe that gives access to a control of the molecular
+asymmetry parameter $\beta$ for individual rotational channels. This is
+achieved by tuning the time delay between the pulses leading to channel
+interferences that can be turned from constructive to destructive. The
+illustrative example is the ionization of the $E(1\Sigma_{g}^{+})$ state of
+Li$_{2}$. Quantum wave packet evolutions are conducted including both
+electronic and nuclear degrees of freedom to reach angle-resolved photoelectron
+spectra. A simple interference model based on coherent phase accumulation
+during the field-free dynamics between the two pulses is precisely exploited to
+control the photoelectron angular distributions from almost isotropic, to
+marked anisotropic.",1903.04198v2
+2019-03-11,Spin-glass state and reversed magnetic anisotropy induced by Cr doping in the Kitaev magnet $α$-RuCl$_3$,"Magnetic properties of the substitution series Ru$_{1-x}$Cr$_x$Cl$_3$ were
+investigated to determine the evolution from the anisotropic Kitaev magnet
+$\alpha$-RuCl$_3$ with $J_{\rm eff} = 1/2$ magnetic Ru$^{3+}$ ions to the
+isotropic Heisenberg magnet CrCl$_3$ with $S = 3/2$ magnetic Cr$^{3+}$ ions.
+Magnetization measurements on single crystals revealed a reversal of the
+magnetic anisotropy under doping, which we argue to arise from the competition
+between anisotropic Kitaev and off-diagonal interactions on the Ru-Ru links and
+approximately isotropic Cr-Ru and isotropic Cr-Cr interactions. In addition,
+combined magnetization, ac susceptibility and specific-heat measurements
+clearly show the destabilization of the long-range magnetic order of
+$\alpha$-RuCl$_3$ in favor of a spin-glass state of Ru$_{1-x}$Cr$_x$Cl$_3$ for
+a low doping of $x\backsimeq0.1$. The corresponding freezing temperature as a
+function of Cr content shows a broad maximum around $x\backsimeq0.45$.",1903.04248v3
+2019-03-14,Black phosphorus nanodevices at terahertz frequencies: photodetectors and future challenges,"The discovery of graphene triggered a rapid rise of unexplored
+two-dimensional materials and heterostructures having optoelectronic and
+photonics properties that can be tailored on the nanoscale. Among these
+materials, black phosphorus (BP) has attracted a remarkable interest thanks to
+many favorable properties, such as high carrier mobility, in-plane anisotropy,
+the possibility to alter its transport via electrical gating and direct
+band-gap, that can be tuned by thickness from 0.3 eV (bulk crystalline) to 1.7
+eV (single atomic layer). When integrated in a microscopic field effect
+transistor (FET), a few-layer BP flake can detect Terahertz (THz) frequency
+radiation. Remarkably, the in-plane crystalline anisotropy can be exploited to
+tailor the mechanisms that dominate the photoresponse; a BP-based field effect
+transistor can be engineered to act as a plasma-wave rectifier, a
+thermoelectric sensor or a thermal bolometer. Here we present a review on
+recent research on BP detectors operating from 0.26 THz to 3.4 THz with
+particular emphasis on the underlying physical mechanisms and the future
+challenges that are yet to be addressed for making BP the active core of stable
+and reliable optical and electronic technologies.",1903.06198v1
+2019-03-15,Shape of the quark gluon plasma droplet reflected in the high-p_T data,"We show, through analytic arguments, numerical calculations, and comparison
+with experimental data, that the ratio of the high-p_T observables v_2/(1-R_AA)
+reaches a well-defined saturation value at high p_T, and that this ratio
+depends only on the spatial anisotropy of the quark gluon plasma (QGP) formed
+in ultrarelativistic heavy-ion collisions. With expected future reduction of
+experimental errors, the anisotropy extracted from experimental data will
+further constrain the calculations of initial particle production in heavy-ion
+collisions and thus test our understanding of QGP physics.",1903.06829v2
+2019-03-19,H-T Phase Diagram of Rare-Earth -- Transition Metal Alloy in the Vicinity of the Compensation Point,"Anomalous hysteresis loops of ferrimagnetic amorphous alloys in high magnetic
+field and in the vicinity of the compensation temperature have so far been
+explained by sample inhomogeneities. We obtain H-T magnetic phase diagram for
+ferrimagnetic GdFeCo alloy using a two-sublattice model in the paramagnetic
+rare-earth ion approximation and taking into account rare-earth (Gd) magnetic
+anisotropy. It is shown that if the magnetic anisotropy of the $f$-sublattice
+is larger than that of the $d$-sublattice, the tricritical point can be at
+higher temperature than the compensation point. The obtained phase diagram
+explains the observed anomalous hysteresis loops as a result of high-field
+magnetic phase transition, the order of which changes with temperature. It also
+implies that in the vicinity of the magnetic compensation point the shape of
+magnetic hysteresis loop is strongly temperature dependent.",1903.07941v1
+2019-03-19,Quasilinear Approach of the Whistler Heat-Flux Instability in the Solar Wind,"The hot beaming (or strahl) electrons responsible for the main electron
+heat-flux in the solar wind are believed to be self-regulated by the
+electromagnetic beaming instabilities, also known as the heat-flux
+instabilities. Here we report the first quasi-linear theoretical approach of
+the whistler unstable branch able to characterize the long-term saturation of
+the instability as well as the relaxation of the electron velocity
+distributions. The instability saturation is not solely determined by the drift
+velocities, which undergo only a minor relaxation, but mainly from a concurrent
+interaction of electrons with whistlers that induces (opposite) temperature
+anisotropies of the core and beam populations and reduces the effective
+anisotropy. These results might be able to (i) explain the low intensity of the
+whistler heat-flux fluctuations in the solar wind (although other explanations
+remain possible and need further investigation), and (ii) confirm a reduced
+effectiveness of these fluctuations in the relaxation and isotropization of the
+electron strahl and in the regulation of the electron heat-flux.",1903.08005v1
+2019-03-20,Hydrodynamic interactions and the diffusivity of spheroidal particles,"It is intuitive that the diffusivity of an isolated particle differs from
+those in a monodisperse suspension, in which hydrodynamic interactions between
+the particles are operative. Batchelor (1976,1983) calculated how hydrodynamic
+interactions influenced the diffusivity of a dilute suspension of spherical
+particles and Russel et al.(1991), and Brady (1994) treated non-dilute (higher
+particle volume fraction) suspensions. Although most particles lack perfect
+sphericity, little is known about the effects of hydrodynamic interactions on
+the diffusivity of spheroidal particles, which are the simplest shapes that can
+be used to model anisotropic particles. Here, we calculate the effects of
+hydrodynamic interactions on the translational and rotational diffusivities of
+spheroidal particles of arbitrary aspect ratio, in dilute monodisperse
+suspensions. The origin of the hydrodynamic anisotropy is that found in the
+stresslet field for the induced-dipole induced-dipole interaction. However, in
+the dilute limit the anisotropy effects are at the level of a few percent.
+These effects have influence in a vast range of settings, from partially frozen
+colloidal suspensions to the dynamics of cytoplasm.",1903.08502v3
+2019-03-22,WKB Approximation for the Polymer Quantization of the Taub Model,"We develop a suitable technical algorithm to implement a separation of the
+Minisuperspace configurational variables into quasi-classical and purely
+quantum degrees of freedom, in the framework of a Polymer quantum Mechanics
+reformulation of the canonical dynamics. We then implement the obtained general
+scheme to the specific case of a Taub Universe, in the presence of a free
+massless scalar field. In particular, we identify the quasi-classical variables
+in the Universe volume and a suitable function of the scalar field, while the
+purely quantum degree of freedom corresponds to the Universe anisotropy. We
+demonstrate that the Taub cosmology is associated to a cyclical Universe,
+oscillating between a minimum and maximum volume turning points, respectively.
+The pure quantum Universe anisotropy has always a finite value.",1903.09417v2
+2019-03-24,Modeling Function-Valued Processes with Nonseparable and/or Nonstationary Covariance Structure,"We discuss a general Bayesian framework on modeling multidimensional
+function-valued processes by using a Gaussian process or a heavy-tailed process
+as a prior, enabling us to handle nonseparable and/or nonstationary covariance
+structure. The nonstationarity is introduced by a convolution-based approach
+through a varying anisotropy matrix, whose parameters vary along the input
+space and are estimated via a local empirical Bayesian method. For the varying
+matrix, we propose to use a spherical parametrization, leading to unconstrained
+and interpretable parameters. The unconstrained nature allows the parameters to
+be modeled as a nonparametric function of time, spatial location or other
+covariates. The interpretation of the parameters is based on closed-form
+expressions, providing valuable insights into nonseparable covariance
+structures. Furthermore, to extract important information in data with complex
+covariance structure, the Bayesian framework can decompose the function-valued
+processes using the eigenvalues and eigensurfaces calculated from the estimated
+covariance structure. The results are demonstrated by simulation studies and by
+an application to wind intensity data. Supplementary materials for this article
+are available online.",1903.09981v2
+2019-03-27,Nonlinear Evolution of Ion Kinetic Instabilities in the Solar Wind,"In-situ observations of the solar wind (SW) plasma from 0.29 to 1AU show that
+the protons and alpha particles are often non-Maxwellian, with evidence of
+kinetic instabilities, temperature anisotropies, differential ion streaming,
+and associated magnetic fluctuations spectra. The kinetic instabilities in the
+SW multi-ion plasma can lead to preferential heating of alpha particles and the
+dissipation of magnetic fluctuation energy, affecting the kinetic and global
+properties of the SW. Using for the first time a three-dimensional hybrid
+model, where ions are modeled as particle using the Particle-In-Cell (PIC)
+method and electrons are treated as fluid, we study the onset, nonlinear
+evolution and dissipation of ion kinetic instabilities. The
+Alfven/ion-cyclotron, and the ion drift instabilities are modeled in the region
+close to the Sun (~10R_s). Solar wind expansion is incorporated in the model.
+The model produces self-consistent non-Maxwellian velocity distribution
+functions (VDFs) of unstable ion populations, the associated temperature
+anisotropies, and wave spectra for several typical SW instability cases in the
+nonlinear growth and saturation stage of the instabilities. The 3D hybrid
+modeling of the multi-ion SW plasma could be used to study the SW acceleration
+region close to the Sun that will be explored by the Parker Solar Probe
+mission.",1903.11343v1
+2019-03-30,Anisotropic pressure induced by finite-size effects in SU(3) Yang-Mills theory,"We study the pressure anisotropy in anisotropic finite-size systems in SU(3)
+Yang-Mills theory at nonzero temperature. Lattice simulations are performed on
+lattices with anisotropic spatial volumes with periodic boundary conditions.
+The energy-momentum tensor defined through the gradient flow is used for the
+analysis of the stress tensor on the lattice. We find that a clear finite-size
+effect in the pressure anisotropy is observed only at a significantly shorter
+spatial extent compared with the free scalar theory, even when accounting for a
+rather large mass in the latter.",1904.00241v2
+2019-04-01,Experimental creation and annihilation of nonvolatile magnetic skyrmions using voltage control of magnetic anisotropy without an external magnetic field,"In this work, we utilize voltage controlled magnetic anisotropy (VCMA) to
+manipulate magnetic skyrmions that are fixed in space. Memory devices based on
+this strategy can potentially be of smaller footprint and better energy
+efficiency than current-controlled motion-based skyrmionic devices. To
+demonstrate VCMA induced manipulation of skyrmions, we fabricate
+antiferromagnet/ferromagnet/oxide heterostructure films where skyrmions can be
+stabilized without any external magnetic field due to the presence of exchange
+bias. These isolated skyrmions were annihilated by applying a voltage pulse
+that increased PMA. On the other hand, decreasing PMA promoted formation of
+more skyrmions. Furthermore, skyrmions can be created from chiral domains by
+increasing PMA of the system. To corroborate our experimental observations, we
+performed micromagnetic simulation. The proposed method could potentially lead
+to novel skyrmion-based memory devices.",1904.00701v1
+2019-04-12,Antiferromagnetic Stacking of Ferromagnetic Layers and Doping Controlled Phase Competition in Ca$_{1-x}$Sr$_{x}$Co$_{2-y}$As$_{2}$,"In search of a quantum phase transition between the two-dimensional ($2$D)
+ferromagnetism of CaCo$_{2-y}$As$_{2}$ and stripe-type antiferromagnetism in
+SrCo$_{2}$As$_{2}$, we rather find evidence for $1$D magnetic frustration
+between magnetic square Co layers. We present neutron diffraction data for
+Ca$_{1-x}$Sr$_{x}$Co$_{2-y}$As$_{2}$ that reveal a sequence of $x$-dependent
+magnetic transitions which involve different stacking of $2$D
+ferromagnetically-aligned layers with different magnetic anisotropy. We explain
+the $x$-dependent changes to the magnetic order by utilizing classical
+analytical calculations of a $1$D Heisenberg model where single-ion magnetic
+anisotropy and frustration of antiferromagnetic nearest- and next-nearest-layer
+exchange are all composition dependent.",1904.06444v2
+2019-04-17,Multifunctional 2D CuSe monolayer nanodevice,"In a very recent experimental work [Gao et al., 2018 Adv. Mater. 30,
+1707055], a graphene-like CuSe monolayer was realized. Motivated by this
+success, we performed first-principles calculations to investigate its
+electronic transport and photoelectronic properties. We find that the CuSe ML
+shows a strong electrical anisotropy, and its current-voltage (I-V) curves
+along the zigzag and armchair directions are noticeably different. The CuSe ML
+also displays a useful negative differential resistance (NDR) effect along the
+both directions when the bias is beyond 1.0 V. Moreover, it has a large photon
+absorption to orange light. Our study suggests that CuSe ML is a
+multifunctional material and has various potential applications in
+electrical-anisotropy-based, NDR-based, and even optical nanodevices.",1904.08047v1
+2019-04-17,Action-based models for dwarf spheroidal galaxies and globular clusters,"A new family of self-consistent DF-based models of stellar systems is
+explored. The stellar component of the models is described by a distribution
+function (DF) depending on the action integrals, previously used to model the
+Fornax dwarf spheroidal galaxy (dSph). The stellar component may cohabit with
+either a dark halo, also described by a DF, or with a massive central black
+hole. In all cases we solve for the model's self-consistent potential.
+Focussing on spherically symmetric models, we show how the stellar observables
+vary with the anisotropy prescribed by the DF, with the dominance and nature of
+the dark halo, and with the mass of the black hole. We show that precise fits
+to the observed surface brightness profiles of four globular clusters can be
+obtained for a wide range of prescribed velocity anisotropies. We also obtain
+precise fits to the observed projected densities of four dSphs. Finally, we
+present a three-component model of the Scupltor dSph with distinct DFs for the
+red and blue horizontal branch stars and the dark matter halo.",1904.08447v1
+2019-04-24,Valley Anisotropy in Elastic Metamaterials,"Valley, as a new degree of freedom, raises the valleytronics in fundamental
+and applied science. The elastic analogs of valley states have been proposed by
+mimicking the symmetrical structure of either two-dimensional materials or
+photonic valley crystals. However, the asymmetrical valley construction remains
+unfulfilled. Here, we present the valley anisotropy by introducing asymmetrical
+design into elastic metamaterials. The elastic valley metamaterials are
+composed of bio-inspired hard spirals and soft materials. The anisotropic
+topological nature of valley is verified by asymmetrical distribution of the
+Berry curvature. We show the high tunability of the Berry curvature both in
+magnitude and sign enabled by our anisotropic valley metamaterials. Finally, we
+demonstrate the creation of valley topological insulators and show
+topologically protected propagation of transverse elastic waves relying on
+operating frequency. The proposed topological properties of elastic valley
+metamaterials pave the way to better understanding the valley topology and to
+creating a new type of topological insulators enabled by an additional valley
+degree of freedom.",1904.11057v1
+2019-05-09,Diffractive dijet production in impact parameter dependent saturation models,"We study coherent diffractive dijet production in electron-hadron and
+electron-nucleus collisions within the dipole picture. We provide semi-analytic
+results for the differential cross section and elliptic anisotropy in the angle
+between dijet transverse momentum and hadron recoil momentum. We demonstrate
+the direct relation between angular moments of the dipole amplitude in
+coordinate space and angular moments of the diffractive dijet cross sections.
+To perform explicit calculations we employ two different saturation models,
+extended to include the target geometry. In the limit of large photon
+virtuality or quark masses, we find fully analytic results that allow direct
+insight into how the differential cross section and elliptic anisotropy depend
+on the saturation scale, target geometry, and kinematic variables. We further
+provide numerical results for more general kinematics in collisions at a future
+electron-ion collider, and study the effects of approaching the saturated
+regime on diffractive dijet observables.",1905.03763v2
+2019-05-11,Anisotropic thermal expansion and thermomechanic properties of monolayer $β$-Te,"Recently, $\beta$-Te (atomically 2D tellurium) with rectangular crystal
+structure has been synthesized successfully on highly oriented pyrolytic
+graphite substrates by using molecular beam epitaxy. It has been found
+possessing remarkable properties such as ultralow lattice thermal conductivity
+and high thermoelectric efficiency. Based on the first-principles calculations,
+we study the thermal expansion and thermomechanic properties of the
+experimental phase monolayer $\beta$-Te, using quasiharmonic approach. It is
+found $\beta$-Te shows large positive thermal expansion at elevated
+temperature, while the linear thermal expansion coefficient is negative along a
+direction at very low temperature. The linear thermal expansion coefficient
+along b direction is 4.9*10$^{-5}$ K$^{-1}$ at 500 K, which is considerably
+large in 2D materials. $\beta$-Te exhibits strong in-plane anisotropy,
+including thermal expansion, 2D elastic moduli and Poisson's ratios. However,
+the elastic moduli, Poisson's ratios and the in-plane anisotropy are weakened
+with increasing temperature, and the variations are dominated by the
+generalized mode Gr\""{u}neisen parameters.",1905.04481v1
+2019-05-11,Primordial bouncing cosmology in the Deser-Woodard nonlocal gravity,"The Deser-Woodard (DW) nonlocal gravity model has been proposed in order to
+describe the late-time acceleration of the universe without introducing dark
+energy. In this paper we focus, however, on the early stage of the universe and
+demonstrate how a primordial bounce in the vacuum spacetime can be realized in
+the framework of the DW nonlocal model. We reconstruct the nonlocal distortion
+function, which encodes all the modifications to the Einstein-Hilbert action,
+in order to generate bouncing solutions to solve the initial singularity
+problem. We show that the initial conditions can be chosen in such a way that
+the distortion function and its first order derivative approach zero after the
+bounce and the standard cosmological solution described by general relativity
+is recovered afterwards. We also study the evolution of anisotropies near the
+bounce. It turns out that the shear density defined by the anisotropy grows
+towards the bounce, but due to the presence of nonlocal effects, it grows in a
+milder manner compared with that in Einstein gravity.",1905.04557v2
+2019-05-14,Phase diagrams of spin-3/2 Blume-Capel model on rectangular lattice under longitudinal magnetic field,"The spin-3/2 Blume-Capel model on a rectangular lattice with the
+ferromagnetic bilinear short-range interaction $K^{\rm F}=K(1+x)$ in one
+direction and the anti-ferromagnetic one $K^{\rm AF}=K(-1+x)$ in the
+perpendicular direction under a longitudinal magnetic field and in the presence
+of a single-ion anisotropy is investigated within the mean field approximation.
+The quantity $x$ characterizes coupling between the interactions in the
+perpendicular directions and its absolute value does not exceed unity. Basing
+on the study of temperature dependencies of sublattice magnetizations the phase
+diagrams in the ($x$, temperature) plane are constructed for different values
+of the longitudinal magnetic field and the single-ion anisotropy. The global
+phase diagram of the model demonstrates an unusual abundance.",1905.05674v1
+2019-05-17,Anisotropy of electronic stopping power in graphite,"The rate of energy transfer from ion projectiles onto the electrons of a
+solid target is hard to determine experimentally in the velocity regime between
+the adiabatic limit and the Bragg peak. First-principles simulations have
+lately offered relevant new insights and quantitative information for
+prototypical homogeneous materials. Here we study the influence of structural
+anisotropy on electronic stopping power with time-dependent density functional
+theory simulations of a hydrogen projectile in graphite. The projectile
+traveled at a range of angles and impact parameters for velocities between 0.1
+and 1.4 a.u., and the electronic stopping power was calculated for each
+simulation. After validation with average experimental data, the anisotropic
+crystal structure was found to have a strong influence on the stopping power,
+with a difference between simulations parallel and perpendicular to the
+graphite plane of up to 25%, more anisotropic than expected based on previous
+work. The velocity dependence at low velocity displays clear linear behavior in
+general, except for projectiles traveling perpendicular to graphitic layers,
+for which a threshold-like behavior is obtained. For projectiles traveling
+along graphitic planes metallic behaviour is observed with a change of slope
+when the projectile velocity reaches the Fermi velocity of the electrons.",1905.07200v2
+2019-05-27,Bianchi models with a free massless scalar field: invariant sets and higher symmetries,"We scrutinize the overall structure of the space of cosmological models of
+Bianchi type I-VII$_h$ that contain a free massless scalar field, with a
+spatially homogeneous gradient $\nabla_\mu \varphi$ that generally breaks
+isotropy, in addition to a standard perfect fluid. Specifically, state space is
+written as a union of disjoint invariant sets, each corresponding to a
+particular cosmological model that is classified with respect to the Bianchi
+type and the matter content. Subsets corresponding to higher-symmetry models,
+including all locally rotationally symmetric models and FLRW models, and models
+with a shear-free normal congruence, are also derived and classified. For each
+model the dimension ($d$) of the space of initial data is given, after fixing
+the orientation of the orthonormal frame uniquely relative to matter
+anisotropies and geometrical anisotropies.",1905.11456v2
+2019-05-30,Interface moment dynamics and its contribution to spin-transfer torque switching process in magnetic tunnel junctions,"A practical problem for memory applications involving perpendicularly
+magnetized magnetic tunnel junctions is the reliability of switching
+characteristics at high-bias voltage. Often it has been observed that at
+high-bias, additional error processes are present that cause a decrease in
+switching probability upon further increase of bias voltage. We identify the
+main cause of such error-rise process through examination of switching
+statistics as a function of bias voltage and applied field, and the junction
+switching dynamics in real time. These experiments show a coincidental onset of
+error-rise and the presence of a new low-frequency microwave emission well
+below that dictated by the anisotropy field. We show that in a few-macrospin
+coupled numerical model, this is consistent with an interface region with
+concentrated perpendicular anisotropy, and where the magnetic moment has
+limited exchange coupling to the rest of the layers. These results point to the
+important role high-frequency interface magnetic moment dynamics play in
+determining the switching characteristics of these tunnel junction devices.",1905.13253v1
+2019-06-05,Supersymmetric Landau-Ginzburg Tensor Models,"We study two dimensional $\mathcal{N} = (2, 2)$ Landau-Ginzburg models with
+tensor valued superfields with the aim of constructing large central charge
+superconformal field theories which are solvable using large $N$ techniques. We
+demonstrate the viability of such constructions and motivate the study of
+anisotropic tensor models. Such theories are a novel deformation of tensor
+models where we break the continuous symmetries while preserving the large $N$
+solvability. Specifically, we examine theories with superpotentials involving
+tensor contractions chosen to pick out melonic diagrams. The anisotropy is
+introduced by further biasing individual terms by different coefficients, all
+of the same order, to retain large $N$ scaling. We carry out a detailed
+analysis of the resulting low energy fixed point and comment on potential
+applications to holography. Along the way we also examine gauged versions of
+the models (with partial anisotropy) and find generically that such theories
+have a non-compact Higgs branch of vacua.",1906.02163v2
+2019-06-07,Shear-induced contact area anisotropy explained by a fracture mechanics model,"This paper gives a theoretical analysis for the fundamental problem of
+anisotropy induced by shear forces onan adhesive contact, discussing the
+experimental data of the companion Letter. We present a fracture mechanicsmodel
+where two phenomenological mode-mixity functions are introduced to describe the
+weak couplingbetween modes I and II or I and III, which changes the effective
+toughness of the interface. The mode-mixityfunctions have been interpolated
+using the data of a single experiment and then used to predict the behavior of
+thewhole set of experimental observations. The model extends an idea by Johnson
+and Greenwood, to solve purelymode I problems of adhesion in the presence of a
+nonaxisymmetric Hertzian geometry, to the case of ellipticalcontacts sheared
+along their major or minor axis. Equality between the stress intensity factors
+and their criticalvalues is imposed solely at the major and minor axes. We
+successfully validate our model against experimentaldata. The model predicts
+that the punch geometry will affect both the shape and the overall decay of the
+shearedcontact area.",1906.02957v1
+2019-06-11,Phase-field material point method for dynamic brittle fracture with isotropic and anisotropic surface energy,"A novel phase field material point method is introduced for robust simulation
+of dynamic fracture in elastic media considering the most general case of
+anisotropic surface energy. Anisotropy is explicitly introduced through a
+properly defined crack density functional. The particular case of impact driven
+fracture is treated by employing a discrete field approach within the material
+point method setting. In this, the equations of motion and phase field
+governing equations are solved independently for each discrete field using a
+predictor-corrector algorithm. Contact at the interface is resolved through
+frictional contact conditions. The proposed method is verified using analytical
+predictions. The influence of surface energy anisotropy and loading conditions
+on the resulting crack paths is assessed through a set of benchmark problems.
+Comparisons are made with the standard Phase Field Finite Element Method and
+experimental observations.",1906.04740v1
+2019-06-11,Effects of the magnetic field direction on the Tsallis statistic,"We extend the use of the Tsallis statistic to measure the differences in gas
+dynamics relative to the mean magnetic field present from natural eddy-type
+motions existing in magnetohydrodynamical (MHD) turbulence. The variation in
+gas dynamics was estimated using the Tsallis parameters on the incremental
+probability distribution function of the observables (intensity and velocity
+centroid) obtained from compressible MHD simulations. We find that the Tsallis
+statistic is susceptible to the anisotropy produce by the magnetic field, even
+when anisotropy is percent the Tsallis statistic can be use to determine MHD
+parameters such as the Sonic Mach number. We quantize the goodness of the
+Tsallis parameters using the coefficient of determination to measure the
+differences in the gas dynamics. These parameters also determine the level of
+magnetization and compressibility of the medium. To further simulate realistic
+spectroscopic observational data we introduced smoothing, noise, and cloud
+boundaries to the MHD simulations.",1906.04821v1
+2019-06-20,Relaxation dynamics and genuine properties of the solvated electron in neutral water clusters,"We have investigated the solvation dynamics and the genuine binding energy
+and photoemission anisotropy of the solvated electron in neutral water clusters
+with a combination of time-resolved photoelectron velocity map imaging and
+electron scattering simulations. The dynamics was probed with a UV probe pulse
+following above-band-gap excitation with a EUV pump pulse. The solvation
+dynamics is completed within about 2 ps. Only a single band is observed in the
+spectra, with no indication for isomers with distinct binding energies. Data
+analysis with an electron scattering model reveals a genuine binding energy in
+the range of 3.55-3.85 eV and a genuine anisotropy parameter in the range of
+0.51-0.66 for the ground-state hydrated electron. All these observations
+coincide with those for liquid bulk, which is rather unexpected for an average
+cluster size of 300 molecules.",1906.08767v3
+2019-07-03,Anisotropy of spin-transfer torques and Gilbert damping induced by Rashba coupling,"Spin-transfer torques (STT), Gilbert damping (GD), and effective spin
+renormalization (ESR) are investigated microscopically in a 2D Rashba
+ferromagnet with spin-independent Gaussian white-noise disorder. Rashba
+spin-orbit coupling induced anisotropy of these phenomena is thoroughly
+analysed. For the case of two partly filled spin subbands, a remarkable
+relation between the anisotropic STT, GD, and ESR is established. In the
+absence of magnetic field and other torques on magnetization, this relation
+corresponds to a current-induced motion of a magnetic texture with the
+classical drift velocity of conduction electrons. Finally, we compute spin
+susceptibility of the system and generalize the notion of spin-polarized
+current.",1907.02041v3
+2019-07-10,"Magneto-Crystalline Anisotropy of Fe, Co and Ni slabs from Density Functional Theory and Tight-Binding models","We report magneto-crystalline anisotropy (MCA) calculations of Fe, Co and Ni
+slabs of various thicknesses and crystallographic orientations from two Density
+Functional Theory codes based either on a plane wave or a local atomic basis
+set expansion and a magnetic tight-binding method. We analyze the evolution of
+the MCA with the number of layers of the slabs. The decomposition of MCA into
+contributions of atomic sites helps understanding the oscillatory behaviour of
+the MCA with the slab thickness and highlights the role of finite size effects.
+We also identify some specific systems with enhanced MCA. A k-space as well as
+a band-filling analysis show very rich features of the MCA that could be used
+to tailor systems with enhanced magnetic properties. Finally this work can
+serve as a benchmark for MCA calculations.",1907.04532v2
+2019-07-11,Correlations between azimuthal anisotropy Fourier harmonics in PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}}=2.76$ TeV in the HYDJET++ and AMPT models,"Correlations between azimuthal anisotropy Fourier harmonics $v_{n}$ ($n = 2,
+3, 4$) are studied using the events from PbPb collisions at
+$\sqrt{s_{_{\mathrm{NN}}}}=2.76$ TeV generated by the HYDJET++ and AMPT models,
+and compared to the corresponding experimental results obtained by the ATLAS
+Collaboration. The Fourier harmonics $v_{n}$ are measured over a wide
+centrality range using the two-particle azimuthal correlation method. The
+slopes of the $v_{2}$--$v_{3}$ correlation from both models are in a good
+agreement with the ATLAS data. The HYDJET++ model predicts a stronger slope for
+the $v_{2}$--$v_{4}$ and $v_{3}$--$v_{4}$ correlations than the ones
+experimentally measured, while the results from the AMPT model are in a rather
+good agreement with the experimental results. In contrast to the HYDJET++
+predictions, the AMPT model predicts a boomerang-like shape in the structure of
+the correlations as found in the experimental data.",1907.05450v2
+2019-07-15,CMB constraints on ultra-light primordial black holes with extended mass distributions,"We examine the effects ultra-light primordial black holes (PBHs) have on the
+anisotropies of the cosmic microwave background (CMB). PBHs in the mass range
+of $10^{15}$ to $10^{17}$ g emit Hawking radiation in the early Universe,
+modifying the standard recombination history. This leads to a damping of
+small-scale temperature and polarisation anisotropies and enhances large-scale
+polarisation fluctuations. As some models of inflation predict PBHs with a
+range of masses, we investigate the impacts of extended mass distributions on
+PBH abundance constraints. We model PBH energy injection using a ground-up
+approach incorporating species-dependent deposition efficiencies. By allowing
+the $\Lambda$CDM parameters to vary simultaneously with the PBH fraction and
+mass, we show that exclusion bounds on the PBH fraction of DM $f_\text{PBH}$
+are relaxed by up to an order of magnitude, compared to the case of fixed
+$\Lambda$CDM parameters. We also give 95% exclusion regions for $f_\text{PBH}$
+for a variety of mass distributions. In particular, for a uniform mass
+distribution between $10^{15}$ and $10^{17}$ g, we find $f_\text{PBH} < 1.6
+\times 10^{-5}$ when allowing $\Lambda$CDM parameters to vary.",1907.06485v1
+2019-07-15,Estimating the angular power spectrum of the gravitational-wave background in the presence of shot noise,"There has been much recent interest in studying anisotropies in the
+astrophysical gravitational-wave (GW) background, as these could provide us
+with interesting new information about galaxy clustering and large-scale
+structure. However, this information is obscured by shot noise, caused by the
+finite number of GW sources that contribute to the background at any given
+time. We develop a new method for estimating the angular spectrum of
+anisotropies, based on the principle of combining statistically-independent
+data segments. We show that this gives an unbiased estimate of the true,
+astrophysical spectrum, removing the offset due to shot noise power, and that
+in the limit of many data segments, it is the most efficient (i.e.
+lowest-variance) estimator possible.",1907.06642v2
+2019-07-19,"Manipulation of spin cluster qubits by electric-field induced modulation of exchange coupling, $g$-factor, and axial anisotropy","Electric fields are increasingly used for coherently manipulating spin states
+in semiconductor and molecular systems. Here we discuss the spin manipulation
+allowed by the modulation of the main parameters entering the Hamiltonians of
+molecular spin clusters. In particular, we focus on transitions between states
+that differ in terms of scalar quantities, such as the total- or the
+partial-spin sums, but have vanishing expectation values of both the total- and
+the single-spin projections. These conditions supposedly define subspaces that
+are immune to the main decoherence mechanisms and that cannot be identified in
+individual spins, where the total- and the partial-spin sums are fixed or
+cannot be defined. We show that the desired transitions can in principle be
+realized in systems as simple as a spin dimer, by modulating the g-factor, the
+axial anisotropy, or, under suitable conditions, the exchange interaction.",1907.08391v2
+2019-07-21,Elastic interactions of Fe adatoms on Cu(111) at the mesoscale,"An extended elastic eigenvector approach had earlier been developed to
+interpret ab-initio calculations of adatom interactions. It shows oscillating
+interactions as well as trio- and quarto (multisite) terms within clusters. It
+is now applied to the interaction of Fe adatoms on Cu(111). The extended
+approach differs from previous calculations by using a sharp cutoff -
+generating oscillating interactions - and by taking into account interacting
+dimers - generating strong anisotropies and multisite terms. Additional weak
+anisotropy stems from the substrate and from the surface Brillouin zone shape.
+This approach has 3 free parameters which have been fitted to first principles
+interactions of Fe adatoms on Cu(111). Elastic adatom pair interactions and
+dimer-dimer interactions at mesoscale separations show a reasonable good fit to
+the first principles interactions. At smaller separations elastic interaction
+values remain questionable. To enable a comparison with future first principle
+calculations also dimer-monomer interactions are shown. Some conclusions on
+initial adatom formation and diffusion are proposed and open questions are
+formulated.",1907.08929v2
+2019-07-21,Weibel-Mediated Shocks Propagating into Inhomogeneous Electron-Positron Plasmas,"The external forward shock emitting the gamma-ray burst (GRB) afterglow is
+collisionless, and it is mediated by the Weibel instability which generates the
+magnetic field. The GRB afterglow shows that the magnetic field in the large
+downstream region is much stronger than the shock-compressed pre-shock field.
+However, particle-in-cell (PIC) simulations of relativistic shocks propagating
+into homogeneous media show that the Weibel generated field decays near the
+shock front. Some GRB observations and theoretical studies suggest that the
+preshock medium is inhomogeneous. We perform the PIC simulation of a
+relativistic shock propagating into inhomogeneous plasma. It is found that the
+post-shock magnetic field decays slowly compared with the homogeneous case.
+Sound waves and entropy waves are also generated by the shock-wave interaction,
+and temperature anisotropy is produced by the sound wave in the downstream
+region. The free energy of the temperature anisotropy is large enough to
+explain the observed field strength. Our results show that the upstream density
+fluctuation has a significant effect in the downstream region of collisionless
+shocks even if the wavelength of the upstream inhomogeneity is much larger than
+the kinetic scale.",1907.08939v1
+2019-07-24,Microsecond electro-optic switching of nematic liquid crystals with giant dielectric anisotropy,"Nematic liquid crystals exhibit a fast optical response when the applied
+electric field modifies the degree of order but does not change the direction
+of molecular orientation. The effect requires a relatively high electric field,
+on the order of 10^8 V/m for a field induced birefringence change of 0.01. To
+address this detrimental issue, this work explores electrically induced
+modification of the order parameter in a material with a giant dielectric
+anisotropy of +200. A relatively weak field 3X10^7 V/m causes a significant
+change of birefringence, by about 0.04. Both switching on and off times are ~10
+microseconds. The effect is called a microsecond electrically modified order
+parameter (MEMOP) and can be used in electro-optical devices, such as fast
+electro-optic shutters, phase modulators, and beam-steerers that require
+microsecond response times.",1907.10227v1
+2019-07-24,Magnetodynamics in orthogonal nanocontact spin-torque nano-oscillators based on magnetic tunnel junctions,"We demonstrate field and current controlled magnetodynamics in nanocontact
+spin-torque nano-oscillators (STNOs) based on orthogonal magnetic tunnel
+junctions (MTJs). We systematically analyze the microwave properties (frequency
+$f$, linewidth $\Delta f$, power $P$, and frequency tunability $df/dI$) with
+their physical origins---perpendicular magnetic anisotropy (PMA), damping-like
+and field-like spin transfer torque (STT), and voltage-controlled magnetic
+anisotropy (VCMA). These devices present several advantageous characteristics:
+high emission frequencies ($f> 20$ GHz), high frequency tunability
+($df/dI=0.25$~GHz/mA), and zero-field operation ($f\sim 4$ GHz). Furthermore, a
+detailed investigation of $f(H, I)$ reveals that $df/dI$ is mostly governed by
+the large VCMA (287~fJ/(V$\cdot$m)), while STT plays a negligible role.",1907.10427v2
+2019-07-24,"Crystal field splitting, local anisotropy, and low energy excitations in the quantum magnet YbCl$_3$","We study the correlated quantum magnet, YbCl$_3$, with neutron scattering,
+magnetic susceptibility, and heat capacity measurements. The crystal field
+Hamiltonian is determined through simultaneous refinements of the inelastic
+neutron scattering and magnetization data. The ground state doublet is well
+isolated from the other crystal field levels and results in an effective
+spin-1/2 system with local easy plane anisotropy at low temperature. Cold
+neutron spectroscopy shows low energy excitations that are consistent with
+nearest neighbor antiferromagnetic correlations of reduced dimensionality.",1907.10627v1
+2019-07-29,An improved interstitial-ice model for pure liquid water,"The main idea of the interstitial-ice model is that liquid water consists of
+an intact hexagonal lattice with both vacant lattice positions and interstitial
+water molecules. Narten, Danford and Levy derived the model parameters from the
+X-ray diffraction patterns of liquid water. However, their results were
+counter-intuitive: their model had almost no vacancies, the interstitial
+concentration was temperature independent and the ice lattice was deformed
+resulting in extra anisotropy. To overcome these problems, we refined the model
+and derived the model parameters from the proton nuclear magnetic resonance
+frequency of pure water. Without any extra anisotropy, a significant
+concentration of vacancies was found (3.7% of the lattice positions at
+0{\deg}C) and the concentration of both the vacancies and interstitials
+increased quasi linear with temperature (0.05 M/{\deg}C). This improved model
+successfully explains the thermodynamic data of water and is therefore a
+promising candidate for a coherent and analytical water model.",1907.12479v3
+2019-07-31,Experimental biases on the heliospheric contribution to the observed TeV cosmic ray anisotropy,"The arrival direction distribution of cosmic ray particles observed on Earth
+is shaped by the cumulative effects of their galactic source locations and of
+trajectory bending in the turbulent interstellar magnetic field. Coherent
+magnetic structures are expected to disrupt particle trajectories and their
+observed distribution, as well. The heliosphere, the large magnetic bubble
+generated by the sweeping effect of solar wind on the local interstellar
+plasma, strongly affects the TeV cosmic ray particles detected on Earth. By
+unfolding the heliospheric influence on the observed anisotropy, it is possible
+to determine the pitch angle distribution of cosmic rays in the interstellar
+medium. This information makes it possible to study in detail the global
+diffusion properties of TeV cosmic rays in the Galaxy. However, observational
+blindness to key features of the cosmic ray arrival direction distribution may
+lead to biases in the determination of the heliospheric influence and of the
+interstellar CR distribution. Any inference of galactic TeV CR diffusion
+properties must carefully account for local propagation phenomena and
+observational limitations.",1908.00067v1
+2019-08-05,Atomistic and mean-field estimates of effective stiffness tensor of nanocrystalline materials of cubic symmetry,"Anisotropic core-shell model of a nano-grained polycrystal, proposed recently
+for nanocrystalline copper, is applied to estimate elastic effective properties
+for a set of crystals of cubic symmetry. Materials selected for analysis differ
+in the lattice geometry (face-centered cubic vs. body-centered cubic) as well
+as the value of a Zener factor: a ratio of two shear moduli defining elastic
+anisotropy of a cubic crystal. The predictions are verified by means of the
+atomistic simulations. The dependence of the overall bulk and shear moduli on
+the average grain diameter is analysed. In the mean-field approach the
+thickness of the shell is specified by the \emph{cutoff radius} of a
+corresponding atomistic potential, while the grain shell is isotropic and its
+properties are identified by molecular simulations performed for very small
+grains with approximately all atoms belonging to the grain boundary zone. It is
+shown that the core-shell model provides predictions of satisfactory
+qualitative and quantitative agreement with atomistic simulations. Performed
+study indicates that the variation of the bulk and shear moduli with the grain
+size changes qualitatively when the Zener anisotropy factor is smaller or
+greater than one.",1908.01644v1
+2019-08-07,Chaotic Effects on Cosmic Ray Anisotropy in a Heliosphere-inspired Model,"Cosmic rays propagate through the Galaxy and encounter systems that may trap
+them temporarily, as well as magnetic field structures that induce chaotic
+behavior on their trajectories. In particular, this is the case for particles
+that propagate in the local interstellar medium and interact with the
+heliospheric magnetic field before being detected on Earth. As a consequence,
+the observed cosmic-ray arrival direction distribution is affected by the
+heliosphere as long as their gyro-radius is smaller or comparable with the
+heliospheric size, i.e. in the TeV energy range. The chaotic nature of those
+cosmic-ray particle trajectories that are temporarily trapped inside the
+heliosphere can be characterized using the Finite-Time Lyapunov Exponents.
+Specifically, we will delve into the case of particles trapped in a
+heliospheric-inspired toy model of a static magnetic bottle configuration and
+the presence of temporal magnetic perturbations. In this work, we also suggest
+that a time-variability could prove to be important in the understanding of the
+TeV cosmic-ray anisotropy at Earth.",1908.02818v1
+2019-08-14,Focusing Surface Acoustic Wave Microcavities on GaAs,"Focusing microcavities for surface acoustic waves (SAWs) produce highly
+localized strain and piezoelectric fields that can dynamically control
+excitations in nanostructures. Focusing transducers (FIDTs) that generate SAW
+beams which match nanostructure dimensions require pattern correction due to
+diffraction and wave velocity anisotropy. The anisotropy correction is normally
+implemented by adding a quadratic term to the dependence of the wave velocity
+on propagation angle. We show that SAW focusing to diffraction limited sizes in
+GaAs requires corrections that more closely follow the group velocity
+wavefront, which is not a quadratic function. Optical interferometric mapping
+of the resultant SAW displacement field reveals tightly focused SAW beams on
+GaAs with a minimal beam waist. An additional set of Gouy phase-corrected
+passive fingers creates an acoustic microcavity in the focal region with small
+volume and high quality factor. Our $\lambda_\mathrm{SAW} = 5.6~\mu$m FIDTs are
+expected to scale well to the $\approx $ 500~nm wavelengths regime needed to
+study strong coupling between vibrations and electrons in electrostatic GaAs
+quantum dots.",1908.04980v3
+2019-08-19,Isotropic charge screening of the anisotropic black phosphorus revealed by potassium adatoms,"Black phosphorus has attracted great research interest due to its numerous
+applications in electronic devices, optoelectronic devices, energy storages and
+so on. Compared with the majority of two-dimensional materials, black
+phosphorus possesses a unique property, i.e. the strong in-plane anisotropy.
+All the properties reported so far, including its effective mass, electron
+mobility, light absorption, thermal conductivity and so on, have shown great
+anisotropy in the basal plane. This property renders black phosphorus unique
+applications not achievable with other two-dimensional materials. In this work,
+however, we discover a remarkable isotropic behavior in the strongly
+anisotropic black phosphorus, i.e. its electrostatic screening of point
+charges. We use the tip-induced band bending of a scanning tunneling microscope
+to map out the Coulomb field of ionized potassium adatoms on black phosphorus,
+and reveal its isotropic charge screening. This discovery is important for
+understanding electron scattering and transport in black phosphorus.",1908.06554v1
+2019-08-20,Light diffusion in birefringent polycrystals and the IceCube ice anisotropy,"The IceCube Neutrino Observatory instruments about 1 km^3 of deep, glacial
+ice at the geographic South Pole with 5160 photomultipliers to detect Cherenkov
+light from charged relativistic particles. The experiment pursues a wide range
+of scientific questions ranging from particle physics such as neutrino
+oscillations to high-energy neutrino astronomy. Most of these efforts rely
+heavily on an ever more precise understanding of the optical properties of the
+instrumented ice. An unexpected light propagation effect, observed by the
+experiment, is an anisotropic attenuation, which is aligned with the local flow
+of the ice. The exact cause is still under investigation. In this contribution,
+the micro-structure of ice as a birefringent polycrystal is explored as the
+cause for this anisotropy.",1908.07608v1
+2019-08-21,Effects of alpha-proton differential flow on proton temperature anisotropy instabilities in the solar wind: Wind observations,"Plasma kinetic waves and alpha-proton differential flow are two important
+subjects on the topic of evolution of the solar wind. Based on the Wind data
+during 2005-2015, this paper reports that the occurrence of electromagnetic
+cyclotron waves (ECWs) near the proton cyclotron frequency significantly
+depends on the direction of alpha-proton differential flow Vd. As Vd rotates
+from anti-Sunward direction to Sunward direction, the occurrence rate of ECWs
+as well as the percentage of left-handed (LH) polarized ECWs decreases
+considerably. In particular, it is shown that the dominant polarization changes
+from LH polarization to right-handed polarization during the rotation. The
+investigation on proton and alpha particle parameters ordered by the direction
+of Vd further illustrates that large kinetic energies of alpha-proton
+differential flow correspond to high occurrence rates of ECWs. These results
+are well consistent with theoretical predictions for effects of alpha-proton
+differential flow on proton temperature anisotropy instabilities.",1908.07680v1
+2019-08-22,Study of the velocity plateau of Dzyaloshinskii domain walls,"We study field-driven domain wall (DW) velocities in asymmetric multilayer
+stacks with perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya
+interaction (DMI), both experimentally and by micromagnetic simulations. Using
+magneto-optical Kerr microscopy under intense and nanoseconds-long fields, we
+show that DWs in these films propagate at velocities up to hundreds of m/s and
+that, instead of the expected decrease of velocity after the Walker field, a
+long plateau with constant velocity is observed, before breakdown. Both the
+maximum speed and the field extent of the velocity plateau strongly depend on
+the values of the spontaneous magnetization and the DMI strength, as well as on
+the magnetic anisotropy. Micromagnetic simulations reproduce these features in
+sufficiently wide strips, even for perfect samples. A physical model explaining
+the microscopic origin of the velocity plateau is proposed.",1908.08282v1
+2019-08-24,Magnetic order and anisotropic interactions induced by mixing between the $J=1/2$ and $3/2$ sectors in spin-orbit coupled honeycomb-lattice compounds,"Novel magnetic ordering on the honeycomb lattice due to emergent weak
+anisotropic interactions generated by the mixing between the $J=1/2$ sector and
+the magnetically inactive 3/2 sector is investigated in a three-orbital
+interacting electron model in the absence of Hund's coupling. Self-consistent
+determination of magnetic order yields anisotropic N\'{e}el and zigzag orders
+for different parameter regimes, highlighting the effect of the emergent
+single-ion anisotropy. Study of magnon excitations shows extremely small magnon
+energy scale compared to the hopping energy scale, and enhancement of
+anisotropy effects for smaller spin-orbit coupling. These results account for
+several features of the honeycomb lattice compounds such as $\rm Na_2 Ir O_3$
+and $\rm Ru Cl_3$, where the leading order anisotropic interactions within the
+magnetically active $J=1/2$ sector are completely quenched due to the
+edge-sharing octahedra.",1908.09130v1
+2019-08-27,A search for cosmological anisotropy using the Lyman alpha forest from SDSS quasar spectra,"The Cosmological Principle, the combined assumptions of cosmological isotropy
+and homogeneity, underpins the standard model of Big Bang cosmology with which
+we interpret astronomical observations. A new test of isotropy over the
+redshift range $2<z<4$ and across large angular scales on the sky is presented.
+We use the cosmological distribution of neutral hydrogen, as probed by the
+Ly$\alpha$ forest seen towards distant quasars. The Sloan Digital Sky Survey
+provides the largest dataset of quasar spectra available to date. We use
+combined information from Data Releases 12 and 14 to select a sample of 142,661
+quasars most suitable for this purpose. The scales covered by the data extend
+beyond post-inflation causality scales, thus probing initial conditions in the
+early universe. We identify significant spatially correlated systematic effects
+that can emulate cosmological anisotropy. Once these systematics have been
+accounted for, the data are found to be consistent with isotropy, providing an
+important independent check on the standard model, consistent with results from
+cosmic microwave background data.",1908.10301v1
+2019-09-03,Single-site magnetic anisotropy governed by inter-layer cation charge imbalance in triangular-lattice AYbX$_2$,"The behavior in magnetic field of a paramagnetic center is characterized by
+its $g$ tensor. An anisotropic form of the latter implies different kind of
+response along different crystallographic directions. Here we shed light on the
+anisotropy of the $g$ tensor of Yb$^{3+}$ 4$f^{13}$ ions in NaYbS$_2$ and
+NaYbO$_2$, layered triangular-lattice materials suggested to host spin-liquid
+ground states. Using quantum chemical calculations we show that, even if the
+ligand-cage trigonal distortions are significant in these compounds, the
+crucial role in realizing strongly anisotropic, `noncubic' $g$ factors is
+played by inter-layer cation charge imbalance effects. The latter refer to the
+asymmetry experienced by a given Yb center due to having higher ionic charges
+at adjacent metal sites within the magnetic $ab$ layer, i.e., 3+ nearest
+neighbors within the ab plane versus 1+ species between the magnetic layers.
+According to our results, this should be a rather general feature of 4$f^{13}$
+layered compounds: less inter-layer positive charge is associated with stronger
+in-plane magnetic response.",1909.01224v1
+2019-09-03,Polarization resolved radiation angular patterns of orientationally ordered nanorods,"We employ the transfer matrix approach combined with the Green's function
+method to theoretically study polarization resolved far-field angular
+distributions of photoluminescence from quantum nanorods (NRs) embedded in an
+anisotropic polymer film. The emission and excitation properties of NRs are
+described by the emission and excitation anisotropy tensors. These tensors and
+the solution of the emission problem expressed in terms of the evolution
+operators are used to derive the orientationally averaged coherency matrix of
+the emitted wavefield. For the case of in-plane alignment and unpolarized
+excitation, we estimate the emission anisotropy parameter and compute the
+angular profiles for the photoluminescence polarization parameter such as the
+degree of linear polarization, the Stokes parameter $s_1$, the ellipticity and
+the polarization azimuth. We show that the alignment order parameter has a
+profound effect on the angular profiles.",1909.01407v2
+2019-09-04,Measurement of azimuthal anisotropy of muons from charm and bottom hadrons in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector,"The elliptic flow of muons from the decay of charm and bottom hadrons is
+measured in $pp$ collisions at $\sqrt{s}=13$ TeV using a data sample with an
+integrated luminosity of 150 pb$^{-1}$ recorded by the ATLAS detector at the
+LHC. The muons from heavy-flavor decay are separated from light-hadron decay
+muons using momentum imbalance between the tracking and muon spectrometers. The
+heavy-flavor decay muons are further separated into those from charm decay and
+those from bottom decay using the distance-of-closest-approach to the collision
+vertex. The measurement is performed for muons in the transverse momentum range
+4-7 GeV and pseudorapidity range $|\eta|<2.4$. A significant non-zero elliptic
+anisotropy coefficient $v_{2}$ is observed for muons from charm decays, while
+the $v_{2}$ value for muons from bottom decays is consistent with zero within
+uncertainties.",1909.01650v2
+2019-09-04,Two-axis cavity optomechanical torque characterization of magnetic microstructures,"Significant new functionality is reported for torsion mechanical tools aimed
+at full magnetic characterizations of both spin statics and dynamics in micro-
+and nanostructures. Specifically, two orthogonal torque directions are
+monitored and the results co-analyzed to separate magnetic moment and magnetic
+susceptibility contributions to torque, as is desired for characterization of
+anisotropic three-dimensional structures. The approach is demonstrated through
+application to shape and microstructural disorder-induced magnetic anisotropies
+in lithographically patterned permalloy, and will have utility for the
+determination of important magnetic thin-film and multilayer properties
+including interface anisotropy and exchange bias. The results reflect
+remarkable sensitivity of the out-of-plane magnetic torque to the nature of
+small edge domains perpendicular to the applied field direction, and also
+contain tantalizing indications of direct coupling to spin dynamics at the
+frequency of the mechanics.",1909.01949v1
+2019-09-05,Large off diagonal exchange couplings and spin liquid states in $\mathbf{C_3}$ symmetric iridates,"Iridate oxides on a honeycomb lattice are considered promising candidates for
+realization of quantum spin liquid states. We investigate the magnetic
+couplings in a structural model for a honeycomb iridate K$_2$IrO$_3$, with
+$C_3$ point group symmetry at the Ir sites, which is an end member of the
+recently synthesized iridate family K$_x$Ir$_y$O$_2$. Using \textit{ab-initio}
+quantum chemical methods, we elucidate the subtle relationship between the real
+space symmetry and magnetic anisotropy and show that the higher point group
+symmetry leads to high frustration with strong magnetic anisotropy driven by
+the unusually large off-diagonal exchange couplings ($\Gamma$'s) as opposed to
+other spin-liquid candidates considered so far. Consequently, large quantum
+fluctuations imply lack of magnetic ordering consistent with the experiments.
+Exact diagonalization calculations for the fully anisotropic $K$-$J$-$\Gamma$
+Hamiltonian reveal the importance of the off-diagonal anisotropic exchange
+couplings in stabilizing a spin liquid state and highlight an alternative route
+to stabilize spin liquid states for ferromagnetic $K$.",1909.02277v1
+2019-09-09,Neural Network Models for the Anisotropic Reynolds Stress Tensor in Turbulent Channel Flow,"Reynolds-averaged Navier-Stokes (RANS) equations are presently one of the
+most popular models for simulating turbulence. Performing RANS simulation
+requires additional modeling for the anisotropic Reynolds stress tensor, but
+traditional Reynolds stress closure models lead to only partially reliable
+predictions. Recently, data-driven turbulence models for the Reynolds
+anisotropy tensor involving novel machine learning techniques have garnered
+considerable attention and have been rapidly developed. Focusing on modeling
+the Reynolds stress closure for the specific case of turbulent channel flow,
+this paper proposes three modifications to a standard neural network to account
+for the no-slip boundary condition of the anisotropy tensor, the Reynolds
+number dependence, and spatial non-locality. The modified models are shown to
+provide increased predicative accuracy compared to the standard neural network
+when they are trained and tested on channel flow at different Reynolds numbers.
+The best performance is yielded by the model combining the boundary condition
+enforcement and Reynolds number injection. This model also outperforms the
+Tensor Basis Neural Network (Ling et al., 2016) on the turbulent channel flow
+dataset.",1909.03591v1
+2019-09-11,Anomalous low-frequency conductivity in easy-plane XXZ spin chains,"In the easy-plane regime of XXZ spin chains, spin transport is ballistic,
+with a Drude weight that has a discontinuous fractal dependence on the value of
+the anisotropy $\Delta = \cos \pi \lambda$ at nonzero temperatures. We show
+that this structure necessarily implies the divergence of the low-frequency
+conductivity for generic irrational values of $\lambda$. Within the framework
+of generalized hydrodynamics, we show that in the high-temperature limit the
+low-frequency conductivity at a generic anisotropy scales as $\sigma(\omega)
+\sim 1/\sqrt{\omega}$; anomalous response occurs because quasiparticles undergo
+L\'evy flights. For rational values of $\lambda$, the divergence is cut off at
+low frequencies and the corrections to ballistic spin transport are diffusive.
+We also use our approach to recover that at the isotropic point $\Delta=1$,
+spin transport is superdiffusive with $\sigma(\omega) \sim \omega^{-1/3}$. We
+support our results with extensive numerical studies using matrix-product
+operator methods.",1909.05263v1
+2019-09-13,Tunable perpendicular exchange bias in oxide heterostructures,"The exchange bias effect is an essential component of magnetic memory and
+spintronic devices. Whereas recent research has shown that anisotropies
+perpendicular to the device plane provide superior stability against thermal
+noise, it has proven remarkably difficult to realize perpendicular exchange
+bias in thin-film structures. Here we demonstrate a strong perpendicular
+exchange bias effect in heterostructures of the quasi-two-dimensional canted
+antiferromagnet La$_2$CuO$_4$ and ferromagnetic (La,Sr)MnO$_3$ synthesized by
+ozone-assisted molecular beam epitaxy. The magnitude of this effect can be
+controlled via the doping level of the cuprate layers. Canted
+antiferromagnetism of layered oxides is thus a new and potentially powerful
+source of uniaxial anisotropy in magnetic devices.",1909.06152v1
+2019-09-18,Anisotropy-induced photonic bound states in the continuum,"Bound states in the continuum (BICs) are radiationless localized states
+embedded in the part of the parameter space that otherwise corresponds to
+radiative modes. Many decades after their original prediction and early
+observations in acoustic systems, such states have been demonstrated recently
+in photonic structures with engineered geometries. Here, we put forward a
+mechanism, based on waveguiding structures that contain anisotropic
+birefringent materials, that affords the existence of BICs with fundamentally
+new properties. In particular, anisotropy-induced BICs may exist in symmetric
+as well as in asymmetric geometries; they form in tunable angular propagation
+directions; their polarization may be pure transverse electric, pure transverse
+magnetic or full vector with tunable polarization hybridity; and they may be
+the only possible bound states of properly designed structures, and thus appear
+as a discrete, isolated bound state embedded in a whole sea of radiative
+states.",1909.08328v1
+2019-09-19,Rashba-splitting of the Dirac points and the symmetry breaking in the strained artificial graphene,"The effect of Rashba spin-orbit interaction and anisotropic strain on the
+electronic, optical and thermodynamic properties of artificial graphene-like
+superlattice composed of InAs-GaAs quantum dots has been considered
+theoretically. The electronic energy dispersions have been obtained using
+Green's function formalism in combination with Fourier transformation to the
+reciprocal space and an exact diagonalization technique. We have observed a
+splitting of Dirac points and appearance of edditional Dirac-like points due to
+the Rashba spin-orbit interaction. Breaking of the hexagonal symmetry of the
+dispersion surfaces caused by the strain anisotropy is observed as well. It is
+shown that both the spin-orbit interaction and strain anisotropy have a
+qualitative impact on the measurable characteristics of the considered
+structure and can be used as effective tools to control the performance of
+devices based on artificial graphene.",1909.08935v1
+2019-09-19,Cosmic Ray Small-Scale Anisotropies in Quasi-Linear Theory,"The distribution of arrival directions of cosmic rays is remarkably
+isotropic, which is a consequence of their repeated scattering in magnetic
+fields. Yet, high-statistics observatories like IceCube and HAWC have revealed
+the presence of small-scale structures at levels of 1 part in 10,000 at
+hundreds of TeV, which are not expected in typical diffusion models of cosmic
+rays. We follow up on the suggestion that these small-scale anisotropies are a
+result of cosmic ray streaming in a particular realisation of the turbulent
+magnetic field within a few scattering lengths in our local Galactic
+neighbourhood. So far, this hypothesis has been investigated mostly
+numerically, by tracking test particles through turbulent magnetic fields. For
+the first time, we present an analytical computation that through a
+perturbative approach allows predicting the angular power spectrum of cosmic
+ray arrival directions for a given model of turbulence. We illustrate this
+method for a simple, isotropic turbulence model and we find remarkable
+agreement with the results of numerical studies.",1909.09052v2
+2019-09-20,Tuning entanglement by squeezing magnons in anisotropic magnets,"We theoretically study the entanglement between two arbitrary spins in a
+magnetic material, where magnons naturally form a general squeezed coherent
+state, in the presence of an applied magnetic field and axial anisotropies.
+Employing concurrence as a measure of entanglement, we demonstrate that spins
+are generally entangled in thermodynamic equilibrium, with the amount of
+entanglement controlled by the external fields and anisotropies. As a result,
+the magnetic medium can serve as a resource to store and process quantum
+information. We, furthermore, show that the entanglement can jump
+discontinuously when decreasing the applied magnetic field. This tunable
+entanglement can be potentially used as an efficient switch in
+quantum-information processing tasks.",1909.09653v2
+2019-09-22,Angular x-ray cross-correlation analysis (AXCCA): Basic concepts and recent applications to soft matter and nanomaterials,"Angular x-ray cross-correlation analysis (AXCCA) is a technique which allows
+quantitative measurement of the angular anisotropy of x-ray diffraction
+patterns and provides insights into the orientational order in the system under
+investigation. This method is based on the evaluation of the angular
+cross-correlation function of the scattered intensity distribution on a
+two-dimensional (2D) detector and further averaging over many diffraction
+patterns for enhancement of the anisotropic signal. Over the last decade, AXCCA
+was successfully used to study the anisotropy in various soft matter systems,
+such as solutions of anisometric particles, liquid crystals, colloidal
+crystals, superlattices composed by nanoparticles, etc. This review provides an
+introduction to the technique and gives a survey of the recent experimental
+work in which AXCCA in combination with micro- or nanofocused x-ray microscopy
+was used to study the orientational order in various soft matter systems.",1909.09973v1
+2019-09-14,The Phase Transition of Square Lattice Antiferromagnets at Finite Temperature,"The magnetic properties of the two-dimensional $J_{1}-J_{2}$ model with both
+exchanges $J_{1}$ and $J_{2}$ being antiferromagnetic and a single-ion
+anisotropy at nonzero temperature are investigated. As $J_{2}/J_{1}<1/2$
+($>1/2$), only the N\'{e}el (collinear) state exists. When $J_{2}/J_{1}=1/2$,
+both the N\'{e}el and collinear states can exist and have the same N\'{e}el
+temperature. The calculated free energies show that there can occur a phase
+transition between the two states below the N\'{e}el point when the single-ion
+anisotropy is strong enough. It is a first-order transition at nonzero
+temperature. It is possible that the doping in real materials can modify the
+ratio of $J_{2}/J_{1}$ to reach $1/2$ so as to implement the phase transition.",1909.11537v1
+2019-10-02,"Investigation of structural and elastic properties of monoclinic Ba$_2$P$_7$X (X $=$ Cl, Br, I) Zintl Salts compounds","Structural and elastic properties of Ba$_{2}$P$_{7}$X (X=Cl, Br, I) (Barium
+Phosphide Halides) Zintl compounds have been investigated using the
+pseudo-potential plane-wave (PP-PW) method based on the density functional
+theory (DFT) within the generalized gradient approximation (GGA-PBESOL). The
+calculated lattice constants and internal parameters are in a good agreement
+with the experimental results reported in literature. In this paper, we present
+an investigation of the relative changes of the structural parameters and
+elastic constants as function of hydrostatic pressure. Isotropic elastic moduli
+and their related properties for single-crystal and polycrystalline phase,
+including the namely bulk modulus, shear modulus, Young's modulus, Poisson's
+ratio, elastic anisotropy indexes, Pugh's indicator of brittle/ductile
+behavior, elastic wave velocities and Debye temperature have been estimated
+from $C_{ij}$ using Voigt, Russ and Hill approximations. Two different methods
+have been used to study the elastic anisotropy of these compounds.",1910.00915v1
+2019-10-08,A generalized Kasner transition for bouncing Bianchi I models in modified gravity theories,"We derive transition rules for Kasner exponents in bouncing Bianchi I models
+with generic perfect fluid matter fields for a broad class of modified gravity
+theories where cosmological singularities are resolved and replaced by a
+non-singular bounce. This is a generalization of results obtained previously in
+limiting curvature mimetic gravity and loop quantum cosmology. A geometric
+interpretation is provided for the transition rule as a linear map in the
+Kasner plane. We show that the general evolution of anisotropies in a Bianchi I
+universe -- including during the bounce phase -- is equivalent to the motion of
+a point particle on a sphere, where the sphere is the one-point
+compactification of the Kasner plane. In addition, we study the evolution of
+anisotropies in a large family of bouncing Bianchi I space-times. We also
+present a novel explicit solution to the Einstein equations for a Bianchi I
+universe with ekpyrotic matter with a constant equation of state $\omega=3$.",1910.03616v2
+2019-10-11,The Optical Properties and Plasmonics of Anisotropic 2-Dimensional Materials,"In the fast growing two-dimensional (2D) materials family, anisotropic 2D
+materials, with their intrinsic in-plane anisotropy, exhibit a great potential
+in optoelectronics. One such typical material is black phosphorus (BP), with a
+layer-dependent and highly tunable band gap. Such intrinsic anisotropy adds a
+new degree of freedom to the excitation, detection and control of light.
+Particularly, hyperbolic plasmons with hyperbolic q-space dispersion are
+predicted to exist in BP films, where highly directional propagating polaritons
+with divergent densities of states are hosted. Combined with a tunable
+electronic structure, such natural hyperbolic surfaces may enable a series of
+exotic applications in nanophotonics. In this review, the anisotropic optical
+properties and plasmons (especially hyperbolic plasmons) of BP are discussed.
+In addition, other possible 2D material candidates (especially anisotropic
+layered semimetals) for hyperbolic plasmons are examined. This review may
+stimulate further research interest in anisotropic 2D materials and fully
+unleash their potential in flatland photonics.",1910.05007v1
+2019-10-11,Spin-reversal energy barriers of 305 K for Fe$^{2+}$ $d^{6}$ ions with linear ligand coordination,"A remarkably large magnetic anisotropy energy of 305 K is computed by quantum
+chemistry methods for divalent Fe$^{2+}$ $d^6$ substitutes at Li-ion sites with
+$D_{6h}$ point-group symmetry within the solid-state matrix of Li$_3$N. This is
+similar to values calculated by the same approach and confirmed experimentally
+for linearly coordinated monovalent Fe$^{1+}$ $d^7$ species, among the largest
+so far in the research area of single-molecule magnets. Our ab initio results
+therefore mark a new exciting exploration path in the search for superior
+single-molecule magnets, rooted in the $d_{xy}^{1.5} d_{x^2-y^2}^{1.5}
+d_{z^2}^1 d_{yz}^1 d_{zx}^1$ configuration of $d^6$ transition-metal ions with
+linear or quasilinear nearest-neighbor coordination. This $d^6$ axial
+anisotropy may be kept robust even for symmetries lower than $D_{6h}$, provided
+the ligand and farther-neighbor environment is engineered such that the
+$d_{xy}^{1.5} d_{x^2-y^2}^{1.5} d_{z^2}^1 d_{yz}^1 d_{zx}^1$ - $d_{xy}^{1}
+d_{x^2-y^2}^{1} d_{z^2}^2 d_{yz}^1 d_{zx}^1$ splitting remains large enough.",1910.05237v1
+2019-10-15,Anisotropy of Cosmic Ray Fluxes Measured with the Alpha Magnetic Spectrometer on the ISS,"A measurement of the dipole anisotropy in galactic coordinates for different
+charged cosmic rays has been performed with the Alpha Magnetic Spectrometer
+(AMS) onboard the International Space Station (ISS). Results are presented for
+the first 7.5 years of data taking for protons, Helium, Carbon and Oxygen, and
+6.5 years for positrons and electrons. All the species are found to be
+consistent with isotropy and upper limits to the dipole amplitude have been
+computed. In particular, for energies above 16 GeV a limit of delta < 1.9% and
+delta < 0.5% at the 95% C.I. is found for positrons and electrons respectively.
+For rigidities above 200 GV a limit of delta < 0.38%, delta < 0.36%, delta <
+1.9% and delta < 1.7% is obtained for protons, Helium, Carbon and Oxygen.",1910.06919v1
+2019-10-17,MoB2:a new multifunctional transition metal diboride monolayer,"Several layered transition metal borides can now be realized by a simple and
+general fabrication method [Fokwa et al.,Adv. Mater. 2018, 30,
+1704181],inspiring our interest to transition metal borides monolayer. Here, we
+predict a new two-dimensional (2D) transition metal diboride MoB2 monolayer
+(ML) and study its intrinsic mechanical, thermal, electronic, and transport
+properties. The MoB2 ML has isotropic mechanic properties along the zigzag and
+armchair directions with a large Young's stiffness, and has an ultralow
+room-temperature thermal conductivity. The Mo atoms dominate the metallic
+nature of MoB2 ML. It shows an obvious electrical anisotropy and a
+current-limiting behavior. Our findings suggest that MoB2 ML is a promising
+multifunctional material used in ultrathin high-strength mechanical materials,
+heat insulating materials, electrical-anisotropy-based materials, and current
+limiters. It is helpful for the experimentalists to further prepare and utilize
+the transition metal diboride 2D materials.",1910.07661v2
+2019-10-17,Controllable splitting dynamics of a doubly quantized vortex in a rotating ring-shaped condensate,"We study the dynamics of a doubly quantized vortex (DQV), created by
+releasing a ring-shaped Bose-Einstein condensate with quantized circulation
+into harmonic potential traps. It is shown that a DQV can be generated and
+exists stably in the middle of the ring-shaped condensate with the initial
+circulation $s = 2$ after released into the rotationally symmetric trap
+potential. For an asymmetric trap with a small degree of anisotropy the DQV
+initially splits into two singly quantized vortices and revives again but
+eventually evolves into two unit vortices due to the dynamic instability. For
+the degree of anisotropy above a critical value, the DQV is extremely unstably
+and decays rapidly into two singlet vortices. The geometry-dependent lifetime
+of the DQV and vortex-induced excitations are also discussed intensively.",1910.07749v1
+2019-10-18,Anisotropy-driven thermal conductivity switching and thermal hysteresis in a ferroelectric,"We present a theoretical proposal for the design of a thermal switch based on
+the anisotropy of the thermal conductivity of PbTiO3 and of the possibility to
+rotate the ferroelectric polarization with an external electric field. Our
+calculations are based on an iterative solution of the phonon Boltzmann
+Transport Equation and rely on interatomic force constants computed within an
+efficient second-principles density functional theory scheme. We also
+characterize the hysteresis cycle of the thermal conductivity in presence of an
+applied electric field and show that the response time would be limited by
+speed of the ferroelectric switch itself and thus can operate in the
+high-frequency regime.",1910.08584v1
+2019-10-21,Prospects of forming high-spin polar molecules from ultracold atoms,"We have investigated Feshbach resonances in collisions of high-spin atoms
+such as Er and Dy with closed-shell atoms such as Sr and Yb, using
+coupled-channel scattering and bound-state calculations. We consider both
+low-anisotropy and high-anisotropy limits. In both regimes we find many
+resonances with a wide variety of widths. The wider resonances are suitable for
+tuning interatomic interactions, while some of the narrower resonances are
+highly suitable for magnetoassociation to form high-spin molecules. These
+molecules might be transferred to short-range states, where they would have
+large magnetic moments and electric dipole moments that can be induced with
+very low electric fields. The results offer the opportunity to study mixed
+quantum gases where one species is dipolar and the other is not, and open up
+important prospects for a new field of ultracold high-spin polar molecules.",1910.09641v4
+2019-10-22,Atomistic picture of fluorescent probes with hydrocarbon tails in lipid bilayer membranes: an investigation of selective affinities and fluorescent anisotropies in different environmental phases,"By reverting to spectroscopy, changes in the biological environment of a
+fluorescent probe can be monitored and the presence of various phases of the
+surrounding lipid bilayer membranes can be detected. This study highlights the
+important differences in orientation and location and therefore in efficiency
+between the probes when they are used in fluorescence microscopy to screen
+various lipid bilayer membrane phases. Dependent on the lipid composition, the
+angle between the transition state dipole moments of both probes and the normal
+to the membrane are found to deviate clearly from 90{\deg}. It is seen that the
+DiI-C18(5) probe is located in the headgroup region of the SM:Chol mixture, in
+close contact with water molecules. A fluorescence anisotropy study indicates
+also that DiI-C18(5) gives rise to a distinctive behavior in the SM:Chol
+membrane compared to the other considered membranes. The latter behavior has
+not been seen for the studied BODIPY probe, which is located deeper in the
+membrane.",1910.09827v1
+2019-10-24,Electron spin resonance in spiral antiferromagnet linarite: theory and experiment,"We present combined experimental and theoretical investigation of the
+low-frequency ESR dynamics in the ordered phases of magnetic mineral linarite.
+This material consists of weakly coupled spin-1/2 chains of copper ions with
+frustrated ferro- and antiferromagnetic interactions. In zero magnetic field,
+linarite orders into a spiral structure and exhibits a peculiar magnetic phase
+diagram sensitive to the field orientation. The resonance frequencies and their
+field dependence are analyzed combining microscopic and macroscopic theoretical
+approaches and precise values of magnetic anisotropy constants are obtained. We
+conclude that possible realization of exotic multipolar quantum states in this
+material is greatly influenced by the biaxial anisotropy.",1910.11056v1
+2019-10-29,Steady one-dimensional domain wall motion in biaxial ferromagnets: mapping of the Landau-Lifshitz equation to the sine-Gordon equation,"Motivated by the difference between the dynamics of magnetization textures in
+ferromagnets and antiferromagnets, the Landau-Lifshitz equation of motion is
+explored. A typical one-dimensional domain wall in a bulk ferromagnet with
+biaxial magnetic anisotropy is considered. In the framework of Walker-type of
+solutions of steady-state ferromagnetic domain wall motion, the reduction of
+the non-linear Landau-Lifshitz equation to a Lorentz-invariant sine-Gordon
+equation typical for antiferromagnets is formally possible for velocities lower
+than a critical velocity of the topological soliton. The velocity dependence of
+the domain wall energy and the domain wall width are expressed in the
+relativistic-like form in the limit of large ratio of the easy-plane/easy-axis
+anisotropy constants. It is shown that the mapping of the Landau-Lifshitz
+equation of motion to the sine-Gordon equation can be performed only by going
+beyond the steady-motion Walker-type of solutions.",1910.13266v2
+2019-10-29,Classical nucleation theory predicts the shape of the nucleus in homogeneous solidification,"Macroscopic models of nucleation provide powerful tools for understanding
+activated phase transition processes. These models do not provide atomistic
+insights and can thus sometime lack material-specific descriptions. Here we
+provide a comprehensive framework for constructing a continuum picture from an
+atomistic simulation of homogeneous nucleation. We use this framework to
+determine the shape of the equilibrium solid nucleus that forms inside bulk
+liquid for a Lennard-Jones potential. From this shape, we then extract the
+anisotropy of the solid-liquid interfacial free energy, by performing a reverse
+Wulff construction in the space of spherical harmonic expansions. We find that
+the shape of the nucleus is nearly spherical and that its anisotropy can be
+perfectly described using classical models.",1910.13481v2
+2019-10-31,Quantum critical nematic fluctuations and spin excitation anisotropy in iron pnictides,"Quantum criticality in iron pnictides involves both the nematic and
+antiferromagnetic degrees of freedom, but the relationship between the two
+types of fluctuations has yet to be clarified. Here we study this problem in
+the presence of a small external uniaxial potential, which breaks the
+$C_4$-symmetry in the B$_{1g}$ sector. We establish an identity that connects
+the spin excitation anisotropy, which is the difference of the dynamical spin
+susceptibilities at $\vec{Q}_1=\left(\pi,0\right)$ and
+$\vec{Q}_2=\left(0,\pi\right)$, with the dynamical magnetic susceptibility and
+static nematic susceptibility. Using this identity, we introduce a scaling
+procedure to determine the dynamical nematic susceptibility in the quantum
+critical regime, and illustrate the procedure for the case of the optimally
+Ni-doped BaFe$_2$As$_2$[Y. Song \textit{et al.}, Phys. Rev. B 92, 180504
+(2015)]. The implications of our results for the overall physics of the
+iron-based superconductors are discussed.",1910.14597v4
+2019-11-04,Physics Beyond The Standard Model with Circular Polarization in the CMB and CMB-21cm Cross-Correlation,"Circular polarization is a relatively unexplored realm of CMB physics. Given
+the substantial community effort towards building next generation CMB
+polarization experiments, including those which will be sensitive to circular
+polarization, it behooves theorists to understand the possible sources and
+relevant physics of circular polarization, as encoded in the Stokes V
+parameter. In this work we develop and derive the requisite formalism, namely
+the Boltzmann hierarchy for V-mode scalar, vector, and tensor, anisotropies. We
+derive the V-mode anisotropies induced by a general source term, and
+demonstrate how existing proposals for the generation of V can be incorporated
+as source terms in the Boltzmann hierarchy. A subset of these effects may be
+correlated with 21cm intensity; we provide a worked example and derive an
+estimator to extract this information from observations. We conclude by
+computing the CMB TV cross-correlation generated by axions, and find a relation
+between TV and VV spectra in axion models.",1911.01418v2
+2019-11-11,Gap Anisotropy in Multiband Superconductors Based on Multiple Scattering Theory,"We implement the Bogoliubov-de Gennes (BdG) equation in a screened
+Korringa-Kohn-Rostoker (KKR) method for solving, self-consistently, the
+superconducting state for 3d crystals. This method combines the full complexity
+of the underlying electronic structure and Fermi surface geometry with a simple
+phenomenological parametrisation for the superconductivity. We apply this
+theoretical framework to the known s-wave superconductors Nb, Pb, and MgB$_2$.
+In these materials multiple distinct peaks at the gap in the density of states
+were observed, showing significant gap anisotropy which is in good agreement
+with experiment. Qualitatively, the results can be explained in terms of the
+k-dependent Fermi velocities on the Fermi surface sheets exploiting concepts
+from BCS theory.",1911.04163v1
+2019-11-25,Fe$_{5-x}$Ge$_2$Te$_2$ -- A new exfoliable itinerant ferromagnet with high Curie temperature and large perpendicular magnetic anisotropy,"Layered van der Waals (vdW) crystals with intrinsic magnetic properties such
+as high Curie temperature (TC) and large perpendicular magnetic anisotropy
+(PMA) are key to the development and application of spintronic devices. The
+ferromagnetic vdW metal Fe3-xGeTe2 (FGT) has gained prominence recently due to
+its high TC (220 K) and strong PMA. Here, we introduce a new metallic vdW
+ferromagnets, Fe5-xGe2Te2 or FG2T, which was successfully synthesized and fully
+characterized. FG2T is a metal that orders ferromagnetically with a very sharp
+transition at 250 K (bulk and single crystal thin flakes) and shows large PMA,
+as found by both experimental and computational studies. This work enables
+novel heterostructure devices with near room temperature capabilities by using
+FG2T as spin injector.",1911.11259v1
+2019-11-26,One-directional thermal transport in densely aligned single-wall carbon nanotube films,"Individual carbon nanotubes (CNTs) possess extremely high thermal
+conductivities. However, the thermal conductivities and their anisotropy of
+macroscopic assemblies of CNTs have so far remained small. Here, we report
+results of directional thermal transport measurements on a nearly-perfectly
+aligned CNT film fabricated via controlled vacuum filtration. We found the
+thermal conductivity to be 43 +- 2.2 W m^-1 K^-1 with a record-high thermal
+anisotropy of 500. From the temperature dependence of the thermal conductivity
+and its agreement with the atomistic phonon transport calculation, we conclude
+that the effect of intertube thermal resistance on heat conduction in the
+alignment direction is negligible because of the large contact area between
+CNTs. These observations thus represent ideal unidirectional thermal transport,
+i.e., the thermal conductivity of the film is determined solely by that of
+individual CNTs.",1911.11340v1
+2019-11-27,Magnetic exchange interactions in monolayer CrI$_3$ from many-body wavefunction calculations,"The marked interplay between the crystalline, electronic, and magnetic
+structure of atomically thin magnets has been regarded as the key feature for
+designing next-generation magneto-optoelectronic devices. In this respect, a
+detailed understanding of the microscopic interactions underlying the magnetic
+responses of these crystals is of primary importance. Here, we combine model
+Hamiltonians with multi-reference configuration interaction wavefunctions to
+accurately determine the strength of the spin couplings in the prototypical
+single-layer magnet CrI$_3$. Our calculations identify the (ferromagnetic)
+Heisenberg exchange interaction $J = -1.44$ meV as the dominant term, being the
+inter-site magnetic anisotropies substantially {weaker}. We also find that
+single-layer CrI$_3$ features an out-of-plane easy axis ensuing from a
+single-ion anisotropy $A = -0.10$ meV, and predict $g$-tensor in-plane
+components $g_{xx} = g_{yy} = 1.90$ and out-of-plane component $g_{zz} = 1.92$.
+In addition, we assess the performance of a dozen widely used density
+functionals against our accurate correlated wavefunctions {calculations} and
+available experimental data, thereby establishing reference results for future
+first-principles investigations. Overall, our findings offer a firm theoretical
+ground to experimental observations.",1911.12150v1
+2019-12-02,On the interaction constant measurement of polarized fermions via sound wave spectra obtained from hydrodynamics with the pressure evolution equation,"Usually, hydrodynamic equations are restricted by the continuity and Euler
+equations. However, the account of the higher moments of the distribution
+function gives better description of the kinetic properties. Therefore, the
+pressure tensor evolution equation (PTEE) is derived for spin polarized
+degenerate fermions. Moreover, it is found that the pressure tensor enters the
+interaction term generalizing the p-wave interaction in the Euler equation.
+Hence, the PTEE allows to give a more accurate description of the interaction
+in Euler equation. Next, the interaction is calculated for the PTEE. The
+developed model is applied to the small amplitude bulk collective excitations
+in homogeneous and trapped fermions in order to suggest the methods of
+experimental measurement of the interaction constant of polarized fermions. It
+is demonstrated that the anisotropy in the momentum space revealing in the
+difference of the pressures in the anisotropy direction and the perpendicular
+directions leads to a method of detection of the interaction constant.",1912.00843v1
+2019-12-09,Anisotropies of galaxy ellipticity correlations in real and redshift space: angular dependence in linear tidal alignment model,"Investigating intrinsic alignments (IAs) of galaxy shapes is important not
+only to constrain cosmological parameters unbiasedly from gravitational lensing
+but also to extract cosmological information complimentary to galaxy clustering
+analysis. We derive simple and useful formulas for the various IA statistics,
+including the intrinsic ellipticity--ellipticity correlation, the gravitational
+shear--intrinsic ellipticity correlation, and the velocity-intrinsic
+ellipticity correlation functions. The angular dependence of each statistic is
+explicitly given, namely the angle between the line-of-sight direction and the
+separation vector of two points. It thus allows us to analyze anisotropies of
+baryon acoustic oscillations encoded in the IA statistics, and we can extract
+the maximum cosmological information using the Alcock-Pacyznski and
+redshift-space distortion effects. We also provide these formulas for the
+intrinsic ellipticities decomposed into E and B modes.",1912.04118v2
+2019-12-16,"Discreteness effects, $N-$body chaos and the onset of radial-orbit instability","We study the stability of a family of spherical equilibrium models of
+self-gravitating systems, the so-called $\gamma-$models with Osipkov-Merritt
+velocity anisotropy, by means of $N-$body simulations. In particular, we
+analyze the effect of self-consistent $N-$body chaos on the onset of
+radial-orbit instability (ROI). We find that degree of chaoticity of the system
+associated to its largest Lyapunov exponent $\Lambda_{\rm max}$ has no
+appreciable relation with the stability of the model for fixed density profile
+and different values of radial velocity anisotropy. However, by studying the
+distribution of the Lyapunov exponents $\lambda_{\rm m}$ of the individual
+particles in the single-particle phase space, we find that more anisotropic
+systems have a larger fraction of orbits with larger $\lambda_{\rm m}$.",1912.07406v2
+2019-12-19,Tuning Ginzburg-Landau theory to quantitatively study thin ferromagnetic materials,"Along with experiments, numerical simulations are key to gaining insight into
+the underlying mechanisms governing domain wall motion in thin ferromagnetic
+systems. However, a direct comparison between numerical simulation of model
+systems and experimental results still represents a great challenge. Here, we
+present a tuned Ginzburg-Landau model to quantitatively study the dynamics of
+domain walls in quasi two-dimensional ferromagnetic systems with perpendicular
+magnetic anisotropy. This model incorporates material and experimental
+parameters and the micromagnetic prescription for thermal fluctuations,
+allowing us to perform material-specific simulations and at the same time
+recover universal features. We show that our model quantitatively reproduces
+previous experimental velocity-field data in the archetypal perpendicular
+magnetic anisotropy Pt/Co/Pt ultra-thin films in the three dynamical regimes of
+domain wall motion (creep, depinning and flow). In addition, we present a
+statistical analysis of the domain wall width parameter, showing that our model
+can provide detailed nano-scale information while retaining the complex
+behavior of a statistical disordered model.",1912.09392v2
+2020-01-01,Pseudo-spin rotation symmetry breaking by Coulomb interaction terms in spin-orbit coupled systems,"By transforming from the pure-spin-orbital ($t_{\rm 2g}$) basis to the
+spin-orbital entangled pseudo-spin-orbital basis, the pseudo-spin rotation
+symmetry of the different Coulomb interaction terms is investigated under SU(2)
+transformation in pseudo-spin space. While the Hubbard and density interaction
+terms are invariant, the Hund's coupling and pair-hopping interaction terms
+explicitly break pseudo-spin rotation symmetry systematically. The form of the
+symmetry-breaking terms obtained from the transformation of the Coulomb
+interaction terms accounts for the easy $x$-$y$ plane anisotropy and magnon gap
+for the out-of-plane mode, highlighting the importance of mixing with the
+nominally non-magnetic $J$=3/2 sector, and providing a physically transparent
+approach for investigating magnetic ordering and anisotropy effects in
+perovskite ($\rm Sr_2 Ir O_4$) and other $d^5$ pseudo-spin compounds.",2001.00190v2
+2020-01-02,Emergence of Superconductivity in Doped Multiorbital Hubbard Chains,"We introduce a variational state for one-dimensional two-orbital Hubbard
+models that intuitively explains the recent computational discovery of pairing
+in these systems when hole doped. Our Ansatz is an optimized linear
+superposition of Affleck-Kennedy-Lieb-Tasaki valence bond states, rendering the
+combination a valence bond liquid dubbed Orbital Resonant Valence Bond. We show
+that the undoped (one electron/orbital) quantum state of two sites coupled into
+a global spin singlet is exactly written employing only spin-1/2 singlets
+linking orbitals at nearest-neighbor sites. Generalizing to longer chains
+defines our variational state visualized geometrically expressing our chain as
+a two-leg ladder, with one orbital per leg. As in Anderson's resonating
+valence-bond state, our undoped variational state contains preformed singlet
+pairs that via doping become mobile leading to superconductivity. Doped real
+materials with one-dimensional substructures, two near-degenerate orbitals, and
+intermediate Hubbard U/W strengths -- W the carrier's bandwidth -- could
+realize spin-singlet pairing if on-site anisotropies are small. If these
+anisotropies are robust, spin-triplet pairing emerges.",2001.00589v2
+2019-11-23,A limit on the anisotropy of the one-way maximum attainable speed of the electron,"We report here the first experimental result for the anisotropy of the
+one-way maximum attainable speed of the electron, $\vec{\Delta c_{1,e}}$,
+obtained via the study of a sidereal time dependence of a difference between
+the electron and positron beam momenta in the CESR storage ring at Cornell
+University. At 95 percent confidence, an upper limit for the component of
+$\Delta \vec {c}_{1,e}/c$ perpendicular to Earth's rotational axis is found to
+be $5.5 \times 10^{-15}$.",2001.00999v3
+2020-01-04,Strain-mediated Symmetry Breaking Switch with Perpendicular Magnetic Anisotropy,"Magnetic switch with perpendicular magnetic anisotropy (PMA) is a promising
+method for controlling magnetization in several applications like magnetic
+tunnel junction and magnetic memory. However, incoherence happens during the
+switch process and lower the switch frequency of the magnetic bits. Symmetry
+broking can help solve this problem. Here, we present a field-free method for
+the symmetry broking and then increase the switch speed of the magnetization. A
+strain-mediated method with geometric asymmetry is presented here. In this
+work, we build a finite element model that consists a 50 nanometer diameter
+nanodisk with a varied thickness on the top of a 50 nanometer thick PZT
+(Pby[ZrxTi1-x]O3) thin film. The results show a 66% faster switch than symmetry
+PMA switching (0.85 nanosecond to 0.29 nanosecond) under same energy
+consumption. Finally, we explore the mechanism of the symmetry broking of
+varying thickness nanodot with calculating the energy profile.",2001.01018v2
+2019-12-19,Heavy Ion Acceleration by Super-Alfvenic Waves,"A generation mechanism of super Alfv\'{e}nic (SPA) waves in multi-ion species
+plasma is proposed and the associated heavy ion acceleration process is
+discussed. The SPA waves are thought to play important roles in particle
+acceleration since they have large wave electric field because of their high
+phase velocity. It is demonstrated by using full particle-in-cell simulation
+that large amplitude proton cyclotron waves, excited due to proton temperature
+anisotropy, nonlinearly destabilize SPA waves through parametric decay
+instability in a three component plasma composed of electrons, protons, and
+$\alpha$ particles. At the same time, $\alpha$ cyclotron waves get excited via
+another decay instability. A pre-accelerated $\alpha$ particle resonates
+simultaneously with the two daughter waves, the SPA waves and the $\alpha$
+cyclotron waves, and it is further accelerated perpendicular to the ambient
+magnetic field. The process may work in astrophysical environments where
+sufficiently large temperature anisotropy of lower mass ions occurs.",2001.02538v1
+2020-01-08,Statistics of relative velocity for particles settling under gravity in a turbulent flow,"We study the joint probability distributions of separation, $R$, and radial
+component of the relative velocity, $V_{\rm R}$, of particles settling under
+gravity in a turbulent flow. We also obtain the moments of these distributions
+and analyze their anisotropy using spherical harmonics. We find that the
+qualitative nature of the joint distributions remains the same as no gravity
+case. Distributions of $V_{\rm R}$ for fixed values of $R$ show a power-law
+dependence on $V_{\rm R}$ for a range of $V_{\rm R}$, exponent of the power-law
+depends on the gravity. Effects of gravity are also manifested in the following
+ways: (a) moments of the distributions are anisotropic; the degree of
+anisotropy depends on particle's Stokes number, but does not depend on $R$ for
+small values of $R$. (b) mean velocity of collision between two particles is
+decreased for particles having equal Stokes numbers but increased for particles
+having different Stokes numbers. For the later, collision velocity is set by
+the difference in their settling velocities.",2001.02724v1
+2020-01-10,Partial quantum revivals of localized condensates in distorted lattices,"We report on a peculiar propagation of bosons loaded by a short
+Laguerre-Gaussian pulse in a nearly flat band of a lattice potential. Taking a
+system of exciton-polaritons in a kagome lattice as an example, we show that an
+initially localized condensate propagates in a specific direction in space if
+anisotropy is taken into account. This propagation consists of quantum jumps,
+collapses, and revivals of the whole compact states, and it persists given any
+direction of anisotropy. This property reveals its signatures in the
+tight-binding model and, surprisingly, it is much more pronounced in a
+continuous model. Quantum revivals are robust to the repulsive interaction and
+finite lifetime of the particles. Since no magnetic field or spin-orbit
+interaction is required, this system provides a new kind of easily
+implementable optical logic.",2001.03317v1
+2020-01-12,Imaging of Strain Driven Magnetic Domains and Strong Spin-Phonon Coupling in Epitaxial Thin Films of SrRuO3,"Epitaxial thin films of SrRuO3 with large strain disorder were grown using
+pulsed laser deposition method which showed two distinct transition
+temperatures in Magnetic measurements. For the first time, we present visual
+evolution of magnetic domains across the two transitions using Magnetic force
+microscopy on these films. The study clearly showed that the magnetic
+anisotropy corresponding to the two transitions is different. It is observed
+that the perpendicular magnetic anisotropy is dominating in films which results
+in domain spin orientation preferably in out of plane direction. The Raman
+studies showed that the lattice is highly influenced by the magnetic order. The
+analysis of the phonon spectra around magnetic transition reveals the existence
+of strong spin-phonon coupling and the calculations resulted in spin-phonon
+coupling strength ({\lambda}) values of {\lambda} ~ 5 cm-1 and {\lambda} ~ 8.5
+cm-1, for SrRuO3 films grown on LSAT and SrTiO3 single crystal substrates,
+respectively.",2001.03901v1
+2020-01-15,Anisotropic behavior of TiB2 nanoparticles reinforced 2024Al composites rolling sheet,"The in-plane anisotropy (IPA) of mechanical properties existed in plate
+products is often undesired since it limits the industrial application and
+increases the difficulty of material processing. It is thus one of the
+important factors which requires strict control during the manufacture of
+high-performance aluminum alloy plates. The anisotropic behavior of TiB2/2024Al
+composite rolling sheet under different heat treatment is studied in this
+article. T4 heat treated specimen shows good isotropy of yield strength and its
+texture components are significantly weakened compared with traditional Al
+alloys. The evolution of microstructures for T4 specimen was studied. The
+submicron TiB2 particles increase the driving force of recrystallization during
+rolling process and static recrystallization (SRX) is stimulated, thus induces
+texture randomization. Anisotropic behavior of yield strength occurs in
+specimen after T3 heat treatment. It is supposed that the difference in the
+activation of slip system under different loading direction gives rise to this
+anisotropy.",2001.05144v1
+2020-01-16,On the linear stability of anisotropic pressure equilibria with field-aligned incompressible flow,"We derive a sufficient condition for the linear stability of plasma
+equilibria with incompressible flow parallel to the magnetic field, $\bf B$,
+constant mass density and anisotropic pressure such that the quantity
+$\sigma_d= \mu_0(P_\parallel -P_\perp)/B^2$, where $P_\parallel$ ($P_\perp$) is
+the pressure tensor element parallel (perpendicular) to $\bf B$, remains
+constant. This condition is applicable to any steady state without geometrical
+restriction. The condition, generalising the respective condition for MHD
+equilibria with isotropic pressure and constant density derived in
+Throumoulopoulos & Tasso (2007), involves physically interpretable terms
+related to the magnetic shear, the flow shear and the variation of total
+pressure perpendicular to the magnetic surfaces. On the basis of this condition
+we prove that if a given equilibrium is linearly stable, then the ones
+resulting from the application of Bogoyavlenskij symmetry transformations are
+linearly stable too, provided that a parameter involved in those
+transformations is positive. In addition, we examine the impact of pressure
+anisotropy, flow, and torsion of a helical magnetic axis, for a specific class
+of analytic equilibria. In this case we find that the pressure anisotropy and
+the flow may have either stabilising or destabilising effects. Also, helical
+configurations with small torsion and large pitch seem to have more favorable
+stability properties.",2001.05750v1
+2020-01-19,Gauge Corrections to Strong Coupling Lattice QCD on Anisotropic Lattices,"Lattice QCD with staggered fermions can be formulated in dual variables to
+address the finite baryon density sign problem. In the past we have performed
+simulations in the strong coupling regime, including leading order gauge
+corrections. In order to vary the temperature for fixed $\beta$ it was
+necessary to introduce a bare anisotropy. In this talk we will extend our work
+to include results from a non-perturbative determination of the physical
+anisotropy $a_\sigma$/$a_\tau = \xi(\gamma, \beta)$, which is necessary to
+unambiguously locate the critical end point and the first order line of the
+chiral transition.",2001.06797v1
+2020-01-22,Effect of the interaction strength and anisotropy on the diffusio-phoresis of spherical colloids,"Gradients in temperature, concentration or electrostatic potential cannot
+exert forces on a bulk fluid; they can, however, exert forces on a fluid in a
+microscopic boundary layer surrounding a (nano)colloidal solute, resulting in
+so-called phoretic flow. Here we present a simulation study of phoretic flow
+around a spherical colloid held fixed in a concentration gradient. We show that
+the resulting flow velocity depends non-monotonically on the strength of the
+colloid-fluid interaction. The reason for this non-monotonic dependence is that
+solute particles are effectively trapped in a shell around the colloid and
+cannot contribute to diffusio-phoresis. We also observe that the flow depends
+sensitively on the anisotropy of solute-colloid interaction.",2001.07959v1
+2020-01-22,Holographic spontaneous anisotropy,"We construct a family of holographic duals to anisotropic states in a
+strongly coupled gauge theory. On the field theory side the anisotropy is
+generated by giving a vacuum expectation value to a dimension three operator.
+We obtain our gravity duals by considering the geometry corresponding to the
+intersection of D3- and D5- branes along 2+1 dimensions. Our backgrounds are
+supersymmetric and solve the fully backreacted equations of motion of
+ten-dimensional supergravity with smeared D5-brane sources. In all cases the
+geometry flows to $AdS_{5}\times {\mathbb S}^5$ in the UV, signaling an
+isotropic UV fixed point of the dual field theory. In the IR, depending on the
+parameters of the solution, we find two possible behaviors: an isotropic fixed
+point or a geometry with anisotropic Lifshitz-like scaling symmetry. We study
+several properties of the solutions, including the entanglement entropy of
+strips. We show that any natural extension of existing $c$-functions will
+display non-monotonic behavior, conforming with the presence of new degrees of
+freedom only at intermediate energy scales.",2001.08218v2
+2020-01-22,On two phases inside the Bose condensation dome of Yb$_2$Si$_2$O$_7$,"Recent experimental data on Bose-Einstein Condensation (BEC) of magnons in
+the spin-gap compound Yb$_2$Si$_2$O$_7$ revealed an asymmetric BEC dome
+arXiv:1810.13096v2. We examine modifications to the Heisenberg model on a
+breathing honeycomb lattice, showing that this physics can be explained by
+competing forms of weak anisotropy. We employ a gamut of analytical and
+numerical techniques to show that the anisotropy yields a field driven phase
+transition from a state with broken Ising symmetry to a phase which breaks no
+symmetries and crosses over to the polarized limit.",2001.08219v2
+2020-01-23,Inelastic neutron scattering study of the anisotropic $S = 1$ spin chain [Ni(HF$_2$)(3-Clpyridine)$_4$]BF$_4$,"[Ni(HF$_2$)(3-Clpyridine)$_4$]BF$_4$ (NBCT) is a one-dimensional, $S = 1$
+spin chain material that shows no magnetic neutron Bragg peaks down
+temperatures of 0.1 K. Previous work identified NBCT to be in the Haldane phase
+and near a quantum phase transition as a function of $D/J$ to the large-$D$
+quantum paramagnet phase (QPM), where $D$ is the axial single-ion anisotropy
+and $J$ is the intrachain superexchange. Herein, inelastic neutron scattering
+results are presented on partially deuterated, $^{11}$B enriched NBCT
+polycrystalline samples in zero magnetic field and down to temperatures of 0.3
+K. Comparison to density matrix renormalization group calculations yields $D/J
+= 1.51$ and a significant rhombic single-ion anisotropy $E$ ($E/D \approx
+0.03$, $E/J \approx 0.05$). These $D$, $J$, and $E$ values place NBCT in the
+large-$D$ QPM phase but precipitously near a quantum phase transition to a
+long-range ordered phase.",2001.08555v1
+2020-01-22,Regularity condition on the anisotropy induced by gravitational decoupling in the framework of MGD,"We use gravitational decoupling to establish a connection between the minimal
+geometric deformation approach and the standard method for obtaining
+anisotropic fluid solutions. Motivated by the relations that appear in the
+framework of minimal geometric deformation, we give an anisotropy factor that
+allows us to solve the quasi--Einstein equations associated to the decoupler
+sector. We illustrate this by building an anisotropic extension of the well
+known Tolman IV solution, providing in this way an exact and physically
+acceptable solution that represents the behavior of compact objects. We show
+that, in this way, it is not necessary to use the usual mimic constraint
+conditions. Our solution is free from physical and geometrical singularities,
+as expected. We have presented the main physical characteristics of our
+solution both analytically and graphically and verified the viability of the
+solution obtained by studying the usual criteria of physical acceptability.",2001.08573v2
+2020-02-01,Estimation of Z-Thickness and XY-Anisotropy of Electron Microscopy Images using Gaussian Processes,"Serial section electron microscopy (ssEM) is a widely used technique for
+obtaining volumetric information of biological tissues at nanometer scale.
+However, accurate 3D reconstructions of identified cellular structures and
+volumetric quantifications require precise estimates of section thickness and
+anisotropy (or stretching) along the XY imaging plane. In fact, many image
+processing algorithms simply assume isotropy within the imaging plane. To
+ameliorate this problem, we present a method for estimating thickness and
+stretching of electron microscopy sections using non-parametric Bayesian
+regression of image statistics. We verify our thickness and stretching
+estimates using direct measurements obtained by atomic force microscopy (AFM)
+and show that our method has a lower estimation error compared to a recent
+indirect thickness estimation method as well as a relative Z coordinate
+estimation method. Furthermore, we have made the first dataset of ssSEM images
+with directly measured section thickness values publicly available for the
+evaluation of indirect thickness estimation methods.",2002.00228v2
+2020-02-03,CMB and BBN constraints on evaporating primordial black holes revisited,"We derive new CMB anisotropy power spectrum and BBN constraints for
+evaporating primordial black holes by explicitly solving the electromagnetic
+particle cascades of emitted particles and the deposition of this emitted
+energy to the background baryon-photon plasma. We show that the CMB
+anisotropies can provide stronger constraints compared to BBN and CMB spectral
+distortions on black holes with masses as small as $M_{\rm BH}=1.1\times
+10^{13}$g, a slightly smaller mass than what has been considered in literature
+until now. We also show that, with more up-to-date data on abundances of
+deuterium and helium-3, BBN constraints are strengthened significantly.",2002.00898v2
+2020-02-04,Localization anisotropy and complex geometry in two-dimensional insulators,"The localization tensor is a measure of distinguishability between insulators
+and metals. This tensor is related to the quantum metric tensor associated with
+the occupied bands in momentum space. In two dimensions and in the
+thermodynamic limit, it defines a flat Riemannian metric over the twist-angle
+space, topologically a torus, which endows this space with a complex structure,
+described by a complex parameter $\tau$. It is shown that the latter is a
+physical observable related to the anisotropy of the system. The quantity
+$\tau$ and the Riemannian volume of the twist-angle space provide an invariant
+way to parametrize the flat quantum metric obtained in the thermodynamic limit.
+Moreover, if by changing the couplings of the theory, the system undergoes
+quantum phase transitions in which the gap closes, the complex structure $\tau$
+is still well defined, although the metric diverges (metallic state), and it is
+fixed by the form of the Hamiltonian near the gap closing points. The
+Riemannian volume is responsible for the divergence of the metric at the phase
+transition.",2002.01312v2
+2020-02-07,Model of damping and anisotropy at elevated temperatures: application to granular FePt films,"Understanding the damping mechanism in finite size systems and its dependence
+on temperature is a critical step in the development of magnetic
+nanotechnologies. In this work, nano-sized materials are modeled via atomistic
+spin dynamics, the damping parameter being extracted from Ferromagnetic
+Resonance (FMR) simulations applied for FePt systems, generally used for
+heat-assisted magnetic recording media (HAMR). We find that the damping
+increases rapidly close to Tc and the effect is enhanced with decreasing system
+size, which is ascribed to scattering at the grain boundaries. Additionally,
+FMR methods provide the temperature dependence of both damping and the
+anisotropy, important for the development of HAMR. Semi-analytical calculations
+show that, in the presence of a grain size distribution, the FMR linewidth can
+decrease close to the Curie temperature due to a loss of inhomogeneous line
+broadening. Although FePt has been used in this study, the results presented in
+the current work are general and valid for any ferromagnetic material.",2002.02865v1
+2020-02-07,Detecting the anisotropic astrophysical gravitational wave background in the presence of shot noise through cross-correlations,"The spatial and temporal discreteness of gravitational wave sources leads to
+shot noise that may, in some regimes, swamp any attempts at measuring the
+anisotropy of the gravitational wave background. Cross-correlating a
+gravitational wave background map with a sufficiently dense galaxy survey can
+alleviate this issue, and potentially recover some of the underlying properties
+of the gravitational wave background. We quantify the shot noise level and we
+explicitly show that cross-correlating the gravitational wave background and a
+galaxy catalog improves the chances of a first detection of the background
+anisotropy with a gravitational wave observatory operating in the frequency
+range (10Hz,100Hz), given sufficient sensitivity.",2002.02888v1
+2020-02-09,Probing Dark Matter with Future CMB Measurements,"Dark Matter (DM) annihilation and decay during the Dark Ages can affect the
+cosmic ionization history and leave imprints in the Cosmic Microwave Background
+(CMB) anisotropy spectra. CMB polarization anisotropy can be sensitive to such
+energy injection at higher redshifts and help reducing degeneracy with
+primordial spectral parameters in $\Lambda$CDM and astrophysical ionization
+processes during reionization. In light of a number of upcoming CMB
+polarization experiments, such as AdvACTPol, AliCPT, CLASS, Simons Observatory,
+Simons Array, SPT-3G, we estimate their prospective sensitivity in probing dark
+matter annihilation and decay signals. We find that future missions have 95\%
+C.L. projected limits on DM decay and annihilation rates to orders of
+$\Gamma_\chi (\tau_{\chi}^{-1}) \sim 10^{-27}{\rm{s}}^{-1}$ and $\left<\sigma v
+\right>/m_{\chi} \sim 10^{-29}{\rm{cm^3s^{-1}GeV^{-1}}}$ respectively,
+significantly improving the sensitivity to DM from current experimental bounds.",2002.03380v2
+2020-02-11,Data Driven Finite Element Method: Theory and Applications,"A data driven finite element method (DDFEM) that accounts for more than two
+material state variables has been presented in this work. DDFEM framework is
+motivated from (1,2) and can account for multiple state variables, viz.
+stresses, strains, strain rates, failure stress, material degradation, and
+anisotropy which has not been used before. DDFEM is implemented in the context
+of linear elements of a nonlinear elastic solid. The presented framework can be
+used for variety of applications by directly using experimental data. This has
+been demonstrated by using the DDFEM framework to predict deformation,
+degradation and failure in diverse applications including nanomaterials and
+biomaterials for the first time. DDFEM capability of predicting unknown and
+unstructured dataset has also been shown by using Delaunay triangulation
+strategy for scattered data having no structure or order. The framework is able
+to capture the strain rate dependent deformation, material anisotropy, material
+degradation, and failure which has not been presented in the past. The
+predicted results show a very good agreement between data set taken from
+literature and DDFEM predictions without requiring to formulate complex
+constitutive models and avoiding tedious material parameter identification.",2002.04446v2
+2020-02-20,Constraining dark photons and their connection to 21 cm cosmology with CMB data,"In the inhomogeneous Universe, the cosmological conversion of dark photons
+into ordinary photons (and vice versa) may happen at a great number of
+resonance redshifts. This alters the CMB observed energy spectrum and degree of
+small-scale anisotropies. We utilize results from the EAGLE simulation to
+obtain the conversion probability along random line-of-sights to quantify these
+effects. We then apply our results to the case where dark photons are sourced
+by dark matter decay and their high-redshift conversion into ordinary photons
+modify the global 21 cm signal expected from the cosmic dawn era. Concretely,
+we show that a significant portion of the parameter space for which a converted
+population of photons in the Rayleigh-Jeans tail of the CMB explains the
+absorption strength observed by EDGES, is ruled out from the brightness
+temperature measurements of COBE/FIRAS and the CMB anisotropy measurements of
+Planck and SPT.",2002.08942v2
+2020-02-21,Determination of spin-orbit torque efficiencies in heterostructures with in-plane magnetic anisotropy,"It has been shown that the spin Hall effect from heavy transition metals can
+generate sufficient spin-orbit torque and further produce current-induced
+magnetization switching in the adjacent ferromagnetic layer. However, if the
+ferromagnetic layer has in-plane magnetic anisotropy, probing such switching
+phenomenon typically relies on tunneling magnetoresistance measurement of
+nano-sized magnetic tunnel junctions, differential planar Hall voltage
+measurement, or Kerr imaging approaches. We show that in magnetic
+heterostructures with spin Hall metals, there exist current-induced in-plane
+spin Hall effective fields and unidirectional magnetoresistance that will
+modify their anisotropic magnetoresistance behavior. We also demonstrate that
+by analyzing the response of anisotropic magnetoresistance under such
+influences, one can directly and electrically probe magnetization switching
+driven by the spin-orbit torque, even in micron-sized devices. This pump-probe
+method allows for efficient and direct determination of key parameters from
+spin-orbit torque switching events without lengthy device fabrication
+processes.",2002.09104v1
+2020-02-22,Molecular static simulation of edge dislocation core in bcc iron,"We simulate the dislocation core structure in bcc iron using the modified
+Molecular Static method. A feature of this method is the application of an
+iterative procedure in which the atomic structure in the vicinity of the defect
+and the constants that determine the displacements of atoms immersed in the
+elastic continuum are calculated in a self-consistent manner. Following the
+mentioned approach, we develop a model for calculating the atomic structure of
+edge dislocations, taking into account the anisotropy of the elastic medium
+surrounding the main calculation cell. Anisotropy is taken into account by
+introducing an explicit angular dependence for the parameters of the elastic
+field created by the dislocation: magnitude of Burgers vector and Poisson's
+ratio. Simulation is carried out for a split dislocation with Burgers vector
+along [100]. The convergence of the iterative algorithm is shown and the
+influence of the computational cell size on the results is considered.
+Calculated results are: atomic structure of dislocation in bcc iron, angular
+dependence of the parameters describing the elastic dislocation field at large
+distances from the dislocation line, and the strain tensor components in the
+entire simulation area.",2002.09601v2
+2020-02-27,Anisotropic Nonequilibrium Lattice Dynamics of Black Phosphorus,"Black phosphorus has recently attracted significant attention for its highly
+anisotropic properties. A variety of ultrafast optical spectroscopies has been
+applied to probe the carrier response to photoexcitation, but the complementary
+lattice response has remained unaddressed. Here we employ femtosecond electron
+diffraction to explore how the structural anisotropy impacts the lattice
+dynamics after photoexcitation. We observe two timescales in the lattice
+response, which we attribute to electron-phonon and phonon-phonon
+thermalization. Pronounced differences between armchair and zigzag directions
+are observed, indicating a nonthermal state of the lattice lasting up to ~60
+ps. This nonthermal state is characterized by a modified anisotropy of the
+atomic vibrations compared to equilibrium. Our findings provide insights in
+both electron-phonon as well as phonon-phonon coupling and bear direct
+relevance for any application of black phosphorus in nonequilibrium conditions.",2002.12038v3
+2020-03-04,Role of Anisotropy in Nonlinear Harmonic Generation Across TMD Monolayers,"Recent techniques have allowed transition metal dichalcogenides (TMD)
+monolayers to be grown and adequately characterised. Of particular interest,
+their nonlinear optical response presents many promising opportunities for
+future nanophotonic devices and technology. The dispersion of the carriers is
+trigonally-warped, leading to an anisotropic Fermi surface for low-lying
+states. In this paper, the effects of such a deformation on the nonlinear
+harmonic generation are studied by considering a tight-binding model expanded
+up to third order in $\mathbf{k} \cdot \mathbf{p}$. By solving exactly the
+free-carrier dynamics of the carriers when interacting with intense and
+ultrashort pulses of light, we predict the photogenerated current in a
+nonperturbative way and study its harmonic composition. We find frequency and
+amplitude modulation of the nonlinear current in quadratic and cubic models.
+Furthermore, we demonstrate anisotropy-induced modulation of the intensity of
+higher-order harmonics and the existence of harmonic crossovers, depending on
+the incident light polarisation. The methodology presented in this paper may be
+applied to any general effective two-band model and offer a pathway to identify
+signatures of electronic features in optical output.",2003.02332v1
+2020-03-08,Voltage-Induced Inertial Domain Wall Motion in an Antiferromagnetic Nanowire,"Racetrack memory based on magnetic domain walls (DWs) motion exhibits
+advantages of small volume and high reading speed. When compared to
+current-induced DW motion, voltage-induced DW motion exhibits lower
+dissipation. On the other hand, the DW in an antiferromagnet (AFM) moves at a
+high velocity with weak stray field. In this work, the AFM DW motion induced by
+a gradient of magnetic anisotropy energy under a voltage pulse has been
+investigated in theory. The dynamics equation for the DW motion was derived.
+The solution indicates that the DW velocity is higher than 100 m/s, and because
+of inertia, the DW is able to keep moving at a speed of around 100 m/s for
+several nano seconds after turning off the voltage in a period of pulse. The
+mechanism for this DW inertia is explained based on the Lagrangian route. On
+the other hand, a spin wave is emitted while the DW is moving, yet the DW is
+still able to move at an ever increasing velocity with enlarging DW width. This
+indicates energy loss from emission of spin wave is less than the energy gain
+from the effective field of the gradient of anisotropy energy.",2003.03784v1
+2020-03-10,Effect of magnons on the temperature dependence and anisotropy of spin-orbit torque,"We investigate the influence of magnons on the temperature-dependence and the
+anisotropy of the spin-orbit torque (SOT). For this purpose we use 3rd order
+perturbation theory in the framework of the Keldysh formalism in order to
+derive suitable equations to compute the magnonic SOT. We find several
+contributions to the magnonic SOT, which depend differently on the spin-wave
+stiffness $\mathcal{A}$ and on the temperature $T$, with the dominating
+contribution scaling like $T^{2}/\mathcal{A}^{2}$. Based on this formalism we
+compute the magnonic SOT in the ferromagnetic Rashba model. For large Rashba
+parameters the magnonic SOT is strongly anisotropic and for small quasiparticle
+broadening it may become larger than the non-magnonic SOT.",2003.05028v3
+2020-03-11,A comparison of two different mechanisms for deterministic spin orbit torque magnetization switching,"In this article we analyze by modeling two possible mechanisms for
+magnetization switching using spin orbit torques, which have been reported to
+cause field-free deterministic switching in experiments. Here we compare the
+field-free magnetization switching due to a tilt of the anisotropy direction
+against the use of an antiferromagnetic bias field. Simple results obtained
+analytically show that a bias field not only causes the magnetization reversal
+but also reduces the corresponding energy barrier. The critical current
+required for magnetization switching is analyzed on the basis of a macrospin
+model. It is shown that although the field-free deterministic switching caused
+by a tilt of the anisotropy is more robust than the bias field in the
+development of memory elements, a compromise between requirements has to be
+adopted when selecting the parameters for specific applications.",2003.05468v1
+2020-03-16,Dynamical spin excitations of topological Haldane gapped phase in the $S=1$ Heisenberg antiferromagnetic chain with single-ion anisotropy,"We study the dynamical spin excitations of the one-dimensional $S=1$
+Heisenberg antiferromagnetic chain with single-ion anisotropy by using quantum
+Monte Carlo simulations and stochastic analytic continuation of imaginary-time
+correlation function. Using the transverse dynamic spin structure factor, we
+observe the quantum phase transition with a critical point between the
+topological Haldane gapped phase and the trivial phase. At the quantum critical
+point, we find a broad continuum characterized by the Tomonaga-Luttinger liquid
+similar to a $S=1/2$ Heisenberg antiferromagnetic chain. We further identify
+that the elementary excitations are fractionalized spinons.",2003.07857v1
+2020-03-28,Dynamic Skyrmion-Mediated Switching of Perpendicular MTJs: Scaling to 20 nm with Thermal Noise,"One method of creating and annihilating skyrmions in confined geometries is
+to use Voltage-Controlled Magnetic Anisotropy (VCMA) [1, 2, 3]. Previous study
+shows that robust voltage controlled ferromagnetic reversal from up to down
+state in the soft layer of a perpendicular Magnetic Tunnel Junction (p-MTJ) can
+be achieved by creating and subsequently annihilating an intermediate skyrmion
+state [4] in the presence of room temperature thermal noise and anisotropy
+variation across grains [4]. However, when scaling to 20 nm, thermal noise can
+annihilate the skyrmions, for example, by randomly moving the core towards the
+boundary of the nanostructure. In this work, we study three p-MTJs of different
+dimensions, particularly lateral dimensions of 100nm, 50nm and 20 nm and
+investigate the change in switching behavior as the dimension is decreased.
+Particularly, our focus is to investigate to what extent skyrmion mediated
+switching scheme can be employed below ~50nm lateral dimensions in the presence
+of thermal perturbation.",2003.12904v1
+2020-03-30,Spontaneous Rotation of Ferrimagnetism Driven by Antiferromagnetic Spin Canting,"Spin-reorientation phase transitions that involve the rotation of a
+crystal$'$s magnetization have been well characterized in distorted-perovskite
+oxides such as the orthoferrites. In these systems spin reorientation occurs
+due to competing rare-earth and transition metal anisotropies coupled via
+$f$-$d$ exchange. Here, we demonstrate an alternative paradigm for spin
+reorientation in distorted perovskites. We show that the
+$R_2\mathrm{CuMnMn_4O_{12}}$ (R = Y or Dy) triple A-site columnar-ordered
+quadruple perovskites have three ordered magnetic phases and up to two
+spin-reorientation phase transitions. Unlike the spin-reorientation phenomena
+in other distorted perovskites, these transitions are independent of rare-earth
+magnetism, but are instead driven by an instability towards antiferromagnetic
+spin canting likely originating in frustrated Heisenberg exchange interactions,
+and the competition between Dzyaloshinskii-Moriya and single-ion anisotropies.",2003.13774v1
+2020-03-31,Strong in-plane anisotropy in the electronic structure of fixed-valence $β$-LuAlB$_4$,"The origin of intrinsic quantum criticality in the heavy-fermion
+superconductor $\beta$-YbAlB$_4$ has been attributed to strong Yb valence
+fluctuations and its peculiar crystal structure. Here, we assess these
+contributions individually by studying the isostructural but fixed-valence
+compound $\beta$-LuAlB$_4$. Quantum oscillation measurements and DFT
+calculations reveal a Fermi surface markedly different from that of
+$\beta$-YbAlB$_4$, consistent with a `large' Fermi surface there. We also find
+an unexpected in-plane anisotropy of the electronic structure, in contrast to
+the isotropic Kondo hybridization in $\beta$-YbAlB$_4$.",2003.14113v1
+2020-04-02,Mechanical orientation of fine magnetic particles in powders by an external magnetic field: simulation-based optimization,"We present a numerical algorithm for predicting the optimal conditions for
+the effective alignment of magnetic particles in dense powders during the
+compactization process using an externally applied field. This task is
+especially important for the permanent magnets development due to the fact that
+alignment of anisotropy axes of nanocomposite grains increases both remanence
+and coercivity of magnetic materials. In contrast to previously known methods
+where magnetic moment of each particle was assumed to be 'fixed' with respect
+to the particle itself, our approach takes into account the (field-dependent)
+deviation of this moment from the particle anisotropy axis that occurs even for
+magnetically 'hard' particles possessing a strong mechanical contact. We show,
+that this deviation leads to the existence of the optimal value of the applied
+field for which the particle orientation (or alignment) time is minimal. The
+influence of the external pressure and internal mechanical friction on the
+details of the compactization/orientation process is also studied.",2004.00868v1
+2020-04-02,Interplay between shell structure and trap deformation in dipolar fermi gases,"Finite fermion systems are known to exhibit shell structure in the
+weakly-interacting regime, as well known from atoms, nuclei, metallic clusters
+or even quantum dots in two dimensions. All these systems have in common that
+the particle interactions between electrons or nucleons are spatially
+isotropic. Dipolar quantum systems as they have been realized with ultra-cold
+gases, however, are governed by an intrinsic anisotropy of the two-body
+interaction that depends on the orientation of the dipoles relative to each
+other. Here we investigate how this interaction anisotropy modifies the shell
+structure in a weakly interacting two-dimensional anisotropic harmonic trap.
+Going beyond Hartree-Fock by applying the so-called ""importance-truncated""
+configuration interaction (CI) method as well as quadratic CI with single- and
+double-substitutions, we show how the magnetostriction in the system may be
+counteracted upon by a deformation of the isotropic confinement, restoring the
+symmetry.",2004.01006v1
+2020-04-05,Optimal control of magnetization reversal in a monodomain particle by means of applied magnetic field,"A complete analytical solution to the optimal reversal of a macrospin with
+easy-axis anisotropy is presented. Optimal control path minimizing the energy
+cost of the reversal is identified and used to derive time-dependent direction
+and amplitude of the optimal switching field. The minimum energy cost of the
+reversal scales inversely with the switching time for fast switching, follows
+an exponential asymptotics for slow switching and reaches the lower limit
+proportional to the energy barrier between the target states and to the damping
+parameter at infinitely long switching time. For a given switching time, the
+energy cost is never smaller than that for a free macrospin. This limitation
+can be bypassed by adding a hard anisotropy axis which activates the internal
+torque in the desired switching direction, thereby significantly reducing the
+energy cost. Comparison between the calculated optimal control path and minimum
+energy path reveals that optimal control does not translate to the minimization
+of the energy barrier, but signifies effective use of the system's internal
+dynamics to aid the desired magnetic transition.",2004.02146v2
+2020-04-05,Magnon spectrum and electron spin resonance in antiferromagnet with large single-ion easy plane anisotropy,"Motivated by recent experiments on quantum magnet
+NiCl$_{2}$-4SC(NH$_{2}$)$_{2}$ (DTN) and its Br-doped counterpart DTNX we
+propose a theoretical description of optical magnon branch in the
+antiferromagnet with large single-ion anisotropy in the magnetically ordered
+phase. In the framework of the 1/S expansion we derive analytical expressions
+for optical magnon with $\mathbf{k}=0$ energy magnetic field dependence
+$\Delta(h)$. It is shown that in the linear spin wave approximation $\Delta(h)$
+is monotonic without extrema whereas first order in 1/S corrections makes it
+drastically different function with a minimum near the center of magnetically
+ordered phase. The latter behaviour was observed in ESR experiments. Moreover,
+we show that $\Delta(h)$ has nontrivial dependence on the system parameters. It
+solves the discrepancy between inelastic neutron scattering data where the
+growth of interaction constants in DTNX with small Br concentration was
+observed and ESR experiments showing almost unchanged $\Delta(h)$ in comparison
+with pure DTN.",2004.02170v2
+2020-04-05,Generalized phase-sensitivity of directional bond-breaking in laser-molecule interaction,"We establish a generalized picture of the phase-sensitivity of laser-induced
+directional bond-breaking using the H$_2$ molecule as the example. We show that
+the well-known proton ejection anisotropy measured with few-cycle pulses arises
+as an amplitude-modulation of an intrinsic anisotropy that is sensitive to the
+laser phase at the ionization time and determined by the molecule's electronic
+structure. Our work furthermore reveals a strong electron-proton correlation
+that may open up a new approach to experimentally accessing the laser-sub-cycle
+intramolecular electron dynamics also in large molecules.",2004.02213v1
+2020-04-15,Antisite disorder in the battery material LiFePO$_4$,"We report detailed magnetometry and high-frequency electron spin resonance
+(HF-ESR) measurements which allow detailed investigation on Li-Fe antisite
+disorder in single-crystalline LiFePO$_4$, i.e., exchange of Fe$^{2+}$- and
+Li$^+$-ions. The data imply that magnetic moments of Fe$^{2+}$-ions at
+Li-positions do not participate in long-range antiferromagnetic order in
+LiFePO$_4$ but form quasi-free moments. Anisotropy axes of the magnetic moments
+at antisite defects are attached to the main crystallographic directions. The
+local character of these moments is confirmed by associated linear resonance
+branches detected by HF-ESR studies. Magnetic anisotropy shows up in
+significant zero-field splittings of $\Delta = 220(3)$~GHz, $\Delta'\sim50$~GHz
+and a highly anisotropic $g$-factor, i.e., $g_\mathrm{a} = 1.4$, $g_\mathrm{b}
+= 2.0$, and $g_\mathrm{c} = 6.3$. We demonstrate a general method to precisely
+determine Fe-antisite disorder in LiFePO$_4$ from magnetic studies which
+implies a density of paramagnetic Fe$^{2+}$-ions at Li-positions of 0.53\%.",2004.07091v1
+2020-04-16,Exchange interaction of hole-spin qubits in double quantum dots in highly anisotropic semiconductors,"We study the exchange interaction between two hole-spin qubits in a double
+quantum dot setup in a silicon nanowire in the presence of magnetic and
+electric fields. Based on symmetry arguments we show that there exists an
+effective spin that is conserved even in highly anisotropic semiconductors,
+provided that the system has a twofold symmetry with respect to the direction
+of the applied magnetic field. This finding facilitates the definition of qubit
+basis states and simplifies the form of exchange interaction for two-qubit
+gates in coupled quantum dots. If the magnetic field is applied along a generic
+direction, cubic anisotropy terms act as an effective spin-orbit interaction
+introducing novel exchange couplings even for an inversion symmetric setup.
+Considering the example of a silicon nanowire double dot, we present the
+relative strength of these anisotropic exchange interaction terms and calculate
+the fidelity of the $\sqrt{\text{SWAP}}$ gate. Furthermore, we show that the
+anisotropy-induced spin-orbit effects can be comparable to that of the direct
+Rashba spin-orbit interaction for experimentally feasible electric field
+strengths.",2004.07658v1
+2020-04-20,Anomalous pressure dependence of the electronic transport and anisotropy in SrIrO3 films,"Iridate oxides display exotic physical properties that arise from the
+interplay between a large spin-orbit coupling and electron correlations. Here,
+we present a comprehensive study of the effects of hydrostatic pressure on the
+electronic transport properties of SrIrO3 (SIO), a system that has recently
+attracted a lot of attention as potential correlated Dirac semimetal. Our
+investigations on untwinned thin films of SIO reveal that the electrical
+resistivity of this material is intrinsically anisotropic and controlled by the
+orthorhombic distortion of the perovskite unit cell. These effects provide
+another evidence for the strong coupling between the electronic and lattice
+degrees of freedom in this class of compounds. Upon increasing pressure, a
+systematic increase of the transport anisotropies is observed. The anomalous
+pressure-induced changes of the resistivity cannot be accounted for by the
+pressure dependence of the density of the electron charge carriers, as inferred
+from Hall effect measurements. Moreover, pressure-induced rotations of the IrO6
+octahedra likely occur within the distorted perovskite unit cell and affect
+electron mobility of this system.",2004.09116v1
+2020-04-24,Observation of magnetic domains in uniaxial magnets via small-angle electron diffraction and Foucault imaging,"Observation of magnetic domains is important in understanding the magnetic
+properties of magnetic materials and devices. In this study, we report that the
+magnetic domains of M-type hexaferrites with uniaxial anisotropy can be
+visualized via small-angle electron diffraction and Foucault imaging. The
+position of the diffraction pattern spots has the same period as that of
+magnetic domains in a Sc-substituted hexaferrite
+(BaFe$_{12-x-\delta}$Sc$_x$Mg$_\delta$O$_{19}$). Conversely, the spots were
+observed four times longer than the period of magnetic domains in hexaferrite
+without substitution (BaFe$_{12}$O$_{19}$), demonstrating the long-range order
+of the Bloch walls. When the specimen was tilted, the magnetic deflection
+effect, as well as the periodic spots of magnetic domains, occurred. Thus, we
+were able to visualize the magnetic domains with different magnetization
+directions and domain orientations by selecting deflection spots. The results
+indicate that the technique utilized in this study is useful in observing the
+magnetic materials with uniaxial anisotropy.",2004.11589v1
+2020-04-24,Spin-phonon interaction induces tunnel splitting in single-molecule magnets,"Quantum tunneling of the magnetization is a major obstacle to the use of
+single-molecule magnets (SMMs) as basic constituents of next-generation storage
+devices. In this context, phonons are often only considered (perturbatively) as
+disturbances that promote the spin system to traverse the anisotropy barrier.
+Here, we demonstrate the ability of phonons to induce a tunnel splitting of the
+ground doublet which then reduces the required bistability due to Landau-Zener
+tunneling of the magnetization. Harmful are those phonons that modify the spin
+Hamiltonian so that its rotational symmetry about the field axis is destroyed.
+In our calculations we treat spins and phonons on the same footing by
+performing quantum calculations of a Hamiltonian where the single-anisotropy
+tensors are coupled to harmonic oscillators.",2004.11735v1
+2020-04-25,Dynamo action in sliding plates of anisotropic electrical conductivity,"With materials of anisotropic electrical conductivity, it is possible to
+generate a dynamo with a simple velocity field, of the type precluded by
+Cowling's theorems with isotropic materials. Following a previous study by
+Ruderman and Ruzmaikin [1] who considered the dynamo effect induced by a
+uniform shear flow, we determine the conditions for the dynamo threshold when a
+solid plate is sliding over another one, both with anisotropic electrical
+conductivity. We obtain numerical solutions for a general class of anisotropy
+and obtain the conditions for the lowest magnetic Reynolds number, using a
+collocation Chebyshev method. In a particular geometry of anisotropy and
+wavenumber, we also derive an analytical solution, where the eigenvectors are
+just combinations of four exponential functions. An explicit analytical
+expression is obtained for the critical magnetic Reynold number. Above the
+critical magnetic Reynold number, we have also derived an analytical expression
+for the growth rate showing that this is a 'very fast' dynamo, extrapolating on
+the 'slow' and 'fast' terminology introduced by Vainshtein and Zeldovich [2].",2004.12244v1
+2020-04-29,High throughput computational screening for two-dimensional magnetic materials based on experimental databases of three-dimensional compounds,"We perform a computational screening for two-dimensional magnetic materials
+based on experimental bulk compounds present in the Inorganic Crystal Structure
+Database and Crystallography Open Database. A recently proposed geometric
+descriptor is used to extract materials that are exfoliable into
+two-dimensional derivatives and we find 85 ferromagnetic and 61
+anti-ferromagnetic materials for which we obtain magnetic exchange and
+anisotropy parameters using density functional theory. For the easy-axis
+ferromagnetic insulators we calculate the Curie temperature based on classical
+Monte Carlo simulations of anisotropic Heisenberg models. We find good
+agreement with the experimentally reported Curie temperatures of known 2D
+ferromagnets and identify 10 potentially exfoliable two-dimensional
+ferromagnets that have not been reported previously. In addition, we find 18
+easy-axis anti-ferromagnetic insulators with several compounds exhibiting very
+strong exchange coupling and magnetic anisotropy.",2004.14460v1
+2020-05-01,Detecting ultra-high energy cosmic ray anisotropies through cross-correlations,"We propose an observable for ultra-high energy cosmic ray (UHECR) physics:
+the harmonic-space cross-correlation power spectrum between the arrival
+directions of UHECRs and the large-scale cosmic structure mapped by galaxies.
+This cross-correlation has not yet been considered in the literature, and it
+permits a direct theoretical modelling of the main astrophysical components. We
+describe the expected form of the cross-correlation and show how, if the
+distribution of UHECR sources trace the large-scale cosmic structure, it could
+be easier to detect with current data than the UHECR auto-correlation.
+Moreover, the cross-correlation is more sensitive to UHECR anisotropies on
+smaller angular scales, more robust to systematic uncertainties, and it could
+be used to determine the redshift distribution of UHECR sources, making it a
+valuable tool in determining their origins and properties.",2005.00244v2
+2020-05-01,Pt and CoB trilayer Josephson $π$ junctions with perpendicular magnetic anisotropy,"We report on the electrical transport properties of Nb based Josephson
+junctions with Pt/Co$_{68}$B$_{32}$/Pt ferromagnetic barriers. The barriers
+exhibit perpendicular magnetic anisotropy, which has the main advantage for
+potential applications over magnetisation in-plane systems of not affecting the
+Fraunhofer response of the junction. In addition, we report that there is no
+magnetic dead layer at the Pt/Co$_{68}$B$_{32}$ interfaces, allowing us to
+study barriers with ultra-thin Co$_{68}$B$_{32}$. In the junctions, we observe
+that the magnitude of the critical current oscillates with increasing thickness
+of the Co$_{68}$B$_{32}$ strong ferromagnetic alloy layer. The oscillations are
+attributed to the ground state phase difference across the junctions being
+modified from zero to $\pi$. The multiple oscillations in the thickness range
+$0.2~\leqslant~d_\text{CoB}~\leqslant~1.4$~nm suggests that we have access to
+the first zero-$\pi$ and $\pi$-zero phase transitions. Our results fuel the
+development of low-temperature memory devices based on ferromagnetic Josephson
+junctions.",2005.00384v2
+2020-05-07,Pressure-dependent Intermediate Magnetic Phase in Thin Fe$_3$GeTe$_2$ Flakes,"We investigated the evolution of ferromagnetism in layered Fe$_3$GeTe$_2$
+flakes under different pressures and temperatures using in situ magnetic
+circular dichroism (MCD) spectroscopy. We found that the rectangle shape of
+hysteretic loop under an out-of-plane magnetic field sweep can sustain below 7
+GPa. Above that pressure, an intermediate state appears at low temperature
+region signaled by an 8-shaped skew hysteretic loop. Meanwhile, the coercive
+field and Curie temperature decrease with increasing pressures, implying the
+decrease of the exchange interaction and the magneto-crystalline anisotropy
+under pressures. The intermediate phase has a labyrinthine domain structure,
+which is attributed to the increase of ratio of exchange interaction to
+magneto-crystalline anisotropy based on Jagla's theory. Moreover, our
+calculation results reveal a weak structural transition around 6 GPa, which
+leads to a drop of the magnetic momentum of Fe ions.",2005.03195v1
+2020-05-07,Detecting quadrupole: a hidden source of magnetic anisotropy for Manganese alloys,"Mn-based alloys exhibit unique properties in the spintronics materials
+possessing perpendicular magnetic anisotropy (PMA) beyond the Fe and Co-based
+alloys. It is desired to figure out the quantum physics of PMA inherent to
+Mn-based alloys, which have never been reported. Here, the origin of PMA in
+ferrimagnetic Mn$_{3-{\delta}}$Ga ordered alloys is investigated to resolve
+antiparallel-coupled Mn sites using x-ray magnetic circular and linear
+dichroism (XMCD/XMLD) and a first-principles calculation. We found that the
+contribution of orbital magnetic moments in PMA is small from XMCD and that the
+finite quadrupole-like orbital distortion through spin-flipped electron hopping
+is dominant from XMLD and theoretical calculations. These findings suggest that
+the spin-flipped orbital quadrupole formations originate from the PMA in
+Mn$_{3-{\delta}}$Ga and bring the paradigm shift in the researches of PMA
+materials using x-ray magnetic spectroscopies.",2005.03249v1
+2020-05-08,Staggered-flux state for rectangular-lattice spin 1/2 Heisenberg antiferromagnet,"We investigate the spin-1/2 Heisenberg model on a rectangular lattice, using
+the Gutzwiller projected variational wave function known as the staggered flux
+state. Using Monte Carlo techniques, the variational parameters and static
+spin-structure factor for different coupling anisotropies $\gamma=J_y/J_x$ are
+calculated. We observe a gradual evolution of the ground state energy towards a
+value which is very close to the 1D estimate provided by the Bethe ansatz and a
+good agreement between the finite size scaling of the energies. The spin-spin
+correlation functions exhibit a power-law decay with varying exponents for
+different anisotropies. Though the lack of N\'eel order makes the staggered
+flux state energetically unfavorable in the symmetric case $\gamma=1$, it
+appears to capture the essence of the system close to 1D. Hence we believe that
+the staggered flux state provides an interesting starting point to explore the
+crossover from quantum disordered chains to the N\'eel ordered 2D square
+lattices.",2005.03928v1
+2020-05-12,Ising superconductivity and magnetism in NbSe$_2$,"Recent studies on superconductivity in NbSe$_2$ have demonstrated a large
+anisotropy in the superconducting critical field when the material is reduced
+to a single monolayer. Motivated by this recent discovery, we use density
+functional theory (DFT) calculations to quantitatively address the
+superconducting properties of bulk and monolayer NbSe$_2$. We demonstrate that
+NbSe$_2$ is close to a ferromagnetic instability, and analyze our results in
+the context of experimental measurements of the spin susceptibility in
+NbSe$_2$. We show how this magnetic instability, which is pronounced in a
+single monolayer, can enable sizeable singlet-triplet mixing of the
+superconducting order parameter, contrary to contemporary considerations of the
+pairing symmetry in monolayer NbSe$_2$, and discuss approaches as to how this
+degree of mixing can be addressed quantitatively within our DFT framework. Our
+calculations also enable a quantitative description of the large anisotropy of
+the superconducting critical field, using DFT calculations of monolayer
+NbSe$_2$ in the normal state",2005.05497v3
+2020-05-12,Anisometric mesoscale nuclear and magnetic texture in sintered Nd-Fe-B magnets,"By means of temperature and wavelength-dependent small-angle neutron
+scattering (SANS) experiments on sintered isotropic and textured Nd-Fe-B
+magnets we provide evidence for the existence of an anisometric structure in
+the microstructure of the textured magnets. This conclusion is reached by
+observing a characteristic cross-shaped angular anisotropy in the total
+unpolarized SANS cross section at temperatures well above the Curie
+temperature. Comparison of the experimental SANS data to a microstructural
+model based on the superquadrics form factor allows us to estimate the shape
+and lower bounds for the size of the structure. Subtraction of the scattering
+cross section in the paramagnetic regime from data taken at room temperature
+provides the magnetic SANS cross section. Surprisingly, the anisotropy of the
+magnetic scattering is very similar to the nuclear SANS signal, suggesting that
+the nuclear structure is decorated by the magnetic moments via spin-orbit
+coupling. Based on the computation of the two-dimensional correlation function
+we estimate lower bounds for the longitudinal and transversal magnetic
+correlation lengths.",2005.05648v1
+2020-05-14,Harmonic fine tuning and triaxial spatial anisotropy of dressed atomic spins,"The addition of a weak oscillating field modifying strongly dressed spins
+enhances and enriches the system quantum dynamics. Through low-order harmonic
+mixing the bichromatic driving generates additional rectified static field
+acting on the spin system. The secondary field allows for a fine tuning of the
+atomic response and produces effects not accessible with a single dressing
+field, such as a spatial triaxial anisotropy of the spin coupling constants and
+acceleration of the spin dynamics. This tuning-dressed configuration introduces
+an extra handle for the system full engineering for quantum control
+applications. Tuning amplitude, harmonic content, spatial orientation and phase
+relation are control parameters. A theoretical analysis, based on perturbative
+approach, is experimentally validated by applying a bichromatic radiofrequency
+field to an optically pumped Cs atomic vapour. We measure the resonance shifts
+produced by tuning fields up to the third harmonic.",2005.07279v3
+2020-05-15,Examination of the four-fifths law for longitudinal third-order moments in incompressible magnetohydrodynamic turbulence in a periodic box,"The four-fifths law for third-order longitudinal moments is examined, by the
+use of direct numerical simulation data on three-dimensional forced
+incompressible magnetohydrodynamic (MHD) turbulence without a uniformly imposed
+magnetic field in a periodic box. The magnetic Prandtl number is set to one,
+and the number of grid points is $512^3$. A generalized
+K\'arm\'an-Howarth-Kolmogorov equation for second-order velocity moments in
+isotropic MHD turbulence is extended to anisotropic MHD turbulence by means of
+a spherical average over the direction of $\textbf{r}$. Here, $\textbf{r}$ is a
+separation vector. The viscous, forcing, anisotropy and nonstationary terms in
+the generalized equation are quantified. It is found that the influence of the
+anisotropic terms on the four-fifths law is negligible at small scales,
+compared to that of the viscous term. However, the influence of the directional
+anisotropy, which is measured by the departure of the third-order moments in a
+particular direction of $\textbf{r}$ from the spherically averaged ones, on the
+four-fifths law is suggested to be substantial, at least in the case studied
+here.",2005.07358v2
+2020-05-16,Imry-Ma phase in O(n) models for space dimensions higher than the lower critical dimensionality,"Systems with continuous symmetry of the vector order parameter containing
+defects of the ""random local field"" or ""random local anisotropy"" types are
+investigated. It is shown that the disordered Imry-Ma phase, in which the order
+parameter follows the spatial fluctuations of the random field or random
+anisotropy direction, can also occur in a coordinate space of dimension d
+higher than the lower critical dimension dl = 4. For this, the hyperplanes of
+dimension m < dl, must exist in the coordinate space in which there is a strong
+exchange interaction between spins, and the interaction between spins belonging
+to adjacent hyperplanes should not exceed a certain critical value.",2005.08091v2
+2020-05-21,Strain and electric-field control of spin-spin interactions in monolayer CrI$_3$,"We investigate the impact of mechanical strains and a perpendicular electric
+field on the electronic and magnetic ground-state properties of two-dimensional
+monolayer CrI$_3$ using density functional theory. We propose a minimal spin
+model Hamiltonian, consisting of symmetric isotropic exchange interactions,
+magnetic anisotropy energy, and Dzyaloshinskii-Moriya (DM) interactions, to
+capture most pertinent magnetic properties of the system. We compute the
+mechanical strain and electric field dependence of various spin-spin
+interactions. Our results show that both the amplitudes and signs of the
+exchange interactions can be engineered by means of strain, while the electric
+field affects only their amplitudes. However, strain and electric fields affect
+both the directions and amplitudes of the DM vectors. The amplitude of the
+magnetic anisotropy energy can also be substantially modified by an applied
+strain. We show that in comparison with an electric field, strain can be more
+efficiently used to manipulate the magnetic and electronic properties of the
+system. Notably, such systematic tuning of the spin interactions is essential
+for the engineering of room-temperature spintronic nanodevices.",2005.10520v1
+2020-05-22,The soft-mode phonons mediated unconventional superconductivity in monolayer 1T'-WTe2,"Recent experiments have tuned the monolayer 1T'-WTe2 to be superconducting by
+electrostatic gating. Here, we theoretically study the phonon-mediated
+superconductivity in monolayer 1T'-WTe2 via charge doping. We reveal that the
+emergence of soft-mode phonons with specific momentum is crucial to give rise
+to the superconductivity in electron-doping regime, whereas no such soft-mode
+phonons and no superconductivity emerge in hole-doping regime. We also find a
+superconducting dome, which can be attributed to the change of Fermi surface
+nesting condition as electron doping. By taking into account the experimentally
+established strong anisotropy of temperature-dependent upper critical field
+H_{c2} between the in-plane and out-of-plane directions, we show that the
+superconducting state probably has the unconventional equal-spin-triplet
+pairing in A_{u} channel of C_{2h} point group. Our studies provide a promising
+understanding to the doping dependent superconductivity and strong anisotropy
+of H_{c2} in monolayer 1T'-WTe2.",2005.11012v2
+2020-05-25,Evidence for biquadratic exchange in the quasi-two-dimensional antiferromagnet FePS$_3$,"FePS$_3$ is a van der Waals compound with a honeycomb lattice that is a good
+example of a two-dimensional antiferromagnet with Ising-like anisotropy.
+Neutron spectroscopy data from FePS3 were previously analysed using a
+straight-forward Heisenberg Hamiltonian with a single-ion anisotropy. The
+analysis captured most of the elements of the data, however some significant
+discrepancies remained. The discrepancies were most obvious at the Brillouin
+zone boundaries. The data are subsequently reanalysed allowing for unequal
+exchange between nominally equivalent nearest-neighbours, which resolves the
+discrepancies. The source of the unequal exchange is attributed to a
+biquadratic exchange term in the Hamiltonian which most probably arises from a
+strong magnetolattice coupling. The new parameters show that there are features
+consistent with Dirac magnon nodal lines along certain Brillouin zone
+boundaries.",2005.12031v1
+2020-05-26,"A Numerical Study on the Effects of Heterogeneity, Anisotropy, and Station Coverage on the Compensated Linear Vector Dipole Component of Deep Earthquake Moment Tensors","The moment tensors of a large portion of deep earthquakes show apparent
+non-double-couple (non-DC) components. Previously, the observed apparent non-DC
+values in deep earthquakes have been attributed to different mechanisms such as
+complex source processes or complicated source medium structures. In this
+paper, we focused on evaluating the second mechanism. We investigated the
+effect of slab heterogeneity, supra-slab anisotropic structure, intra-slab
+weakly anisotropic structure (e.g., the purported existence of the metastable
+olivine wedge), and non-uniform station coverage, on the non-DC radiation
+patterns of deep earthquakes using our 3-dimensional elastic finite-difference
+modeling and full-waveform inversion of moment tensors. We found that these
+investigated issues cannot cause the observed non-double-couple radiation
+patterns and the in-situ structure with strong S-wave anisotropy near to the
+earthquake focus is the simplest way to account for the apparent non-DC
+components in the radiation patterns of deep earthquakes.",2005.12465v1
+2020-05-27,Inducing anisotropies in Dirac fermions by periodic driving,"We consider the three-dimensional Hamiltonian for Bi$_2$Se$_3$, a
+second-generation topological insulator, under the effect of a periodic drive
+for both in-plane and out-of-plane fields. As it will be shown by means of
+high-frequency expansions up to second order in the Floquet Hamiltonian, the
+driving induces anisotropies in the Dirac cone and opens up a quasienergy gap
+for in-plane elliptically polarized fields. Analytic expressions are obtained
+for the renormalized velocities and the quasienergy gap. These expressions are
+then compared to numerical calculations performed by discretizing the
+Hamiltonian in a one-dimensional lattice and following a staggered fermion
+approach, achieving a remarkable agreement. We believe our work may have an
+impact on the transport properties of topological insulators.",2005.13351v1
+2020-05-27,Crossover from Diffusive to Superfluid Transport in Frustrated Magnets,"We investigate the spin transport across the magnetic phase diagram of a
+frustrated antiferromagnetic insulator and uncover a drastic modification of
+the transport regime from spin diffusion to spin superfluidity. Adopting a
+triangular lattice accounting for both nearest neighbor and next-nearest
+neighbor exchange interactions with easy-plane anisotropy, we perform atomistic
+spin simulations on a two-terminal configuration across the full magnetic phase
+diagram. We found that as long as the ground state magnetic moments remain
+in-plane, irrespective of whether the magnetic configuration is ferromagnetic,
+collinear or non-collinear antiferromagnetic, the system exhibits spin
+superfluid behavior with a device output that is independent on the value of
+the exchange interactions. When the magnetic frustration is large enough to
+compete with the easy-plane anisotropy and cant the magnetic moments out of the
+plane, the spin transport progressively evolves towards the diffusive regime.
+The robustness of spin superfluidity close to magnetic phase boundaries is
+investigated and we uncover the possibility for {\em proximate} spin
+superfluidity close to the ferromagnetic transition.",2005.13481v2
+2020-06-11,Layering of magnetic nanoparticles at amorphous magnetic templates with perpendicular anisotropy,"We reveal the assembly of monodisperse magnetite nanoparticles of sizes 5 nm,
+15 nm and 25 nm from dilute water-based ferrofluids onto an amorphous magnetic
+template with out-of-plane anisotropy. From neutron reflectometry experiments
+we extract density profiles and show that the particles self-assemble into
+layers at the magnetic surface. The layers are extremely stable against
+cleaning and rinsing of the substrate. The density of the layers is determined
+by and increases with the remanent magnetic moment of the particles.",2006.06262v1
+2020-06-12,Enhanced Stability of Antiferromagnetic Skyrmion during Its Motion by Anisotropic Dzyaloshinskii Moriya Interaction,"Searching for new methods to enhance the stability of antiferromagnetic (AFM)
+skyrmion during its motion is an important issue for AFM spintronic devices.
+Herein, the spin polarized current-induced dynamics of a distorted AFM skyrmion
+is numerically studied, based on the Landau Lifshitz Gilbert simulations of the
+model with an anisotropic Dzyaloshinskii Moriya (DM) interaction. It is
+demonstrated that the DM interaction anisotropy induces the skyrmion
+deformation, which suppresses the distortion during the motion and enhances the
+stability of the skyrmion. Moreover, the effect of the DM interaction
+anisotropy on the skyrmion velocity is investigated in detail, and the
+simulated results are further explained by Thiele theory. This work unveils a
+promising strategy to enhance the stability and the maximum velocity of AFM
+skyrmion, benefiting future spintronic applications.",2006.06938v1
+2020-06-14,Structural phase diagram of LaO1-xFxBiSSe: suppression of the structural phase transition by partial F substitutions,"We have investigated low-temperature crystal structure of BiCh2-based
+compounds LaO1-xFxBiSSe (x = 0, 0.01, 0.02, 0.03, and 0.5), in which anomalous
+two-fold-symmetric in-plane anisotropy of superconducting states has been
+observed for x = 0.5. From synchrotron X-ray diffraction experiments, a
+structural transition from tetragonal to monoclinic was observed for x = 0 and
+0.01 at 340 and 240 K, respectively. For x = 0.03, a structural transition and
+broadening of the diffraction peak were not observed down to 100 K. These facts
+suggest that the structural transition could be suppressed by 3% F substitution
+in LaO1-xFxBiSSe. Furthermore, the crystal structure for x = 0.5 at 4 K was
+examined by low-temperature (laboratory) X-ray diffraction, which confirmed
+that the tetragonal structure is maintained at 4 K for x = 0.5. Our results
+suggest that the two-fold-symmetric in-plane anisotropy of superconducting
+states observed for LaO0.5F0.5BiSSe was not originated from structural symmetry
+lowering.",2006.07798v2
+2020-06-17,Neural Anisotropy Directions,"In this work, we analyze the role of the network architecture in shaping the
+inductive bias of deep classifiers. To that end, we start by focusing on a very
+simple problem, i.e., classifying a class of linearly separable distributions,
+and show that, depending on the direction of the discriminative feature of the
+distribution, many state-of-the-art deep convolutional neural networks (CNNs)
+have a surprisingly hard time solving this simple task. We then define as
+neural anisotropy directions (NADs) the vectors that encapsulate the
+directional inductive bias of an architecture. These vectors, which are
+specific for each architecture and hence act as a signature, encode the
+preference of a network to separate the input data based on some particular
+features. We provide an efficient method to identify NADs for several CNN
+architectures and thus reveal their directional inductive biases. Furthermore,
+we show that, for the CIFAR-10 dataset, NADs characterize the features used by
+CNNs to discriminate between different classes.",2006.09717v2
+2020-06-19,Laser-induced ultrafast demagnetization and perpendicular magnetic anisotropy reduction in a Co$_{88}$Tb$_{12}$ thin film with stripe domains,"We use time-resolved x-ray resonant magnetic scattering (tr-XRMS) at the Co
+M$_{2,3}$- and Tb O$_1$-edges to study ultrafast demagnetization in an
+amorphous Co$_{88}$Tb$_{12}$ alloy with stripe domains. Combining the
+femtosecond temporal with nanometer spatial resolution of our experiment, we
+demonstrate that the equilibrium spin texture of the thin film remains
+unaltered by the optical pump-pulse on ultrashort timescales ($<$1 ps).
+However, after $\simeq$ 4 ps, we observe the onset of a significant domain wall
+broadening, which we attribute to a reduction of the uniaxial magnetic
+anisotropy of the system, due to energy transfer to the lattice. Static
+temperature dependent magnetometry measurements combined with analytical
+modeling of the magnetic structure of the thin film corroborate this
+interpretation.",2006.11246v1
+2020-06-22,"Tunable Low-Loss Hyperbolic Plasmon Polaritons in a T$_{d}\,$-WTe$_2$ Single Layer","Natural hyperbolic two-dimensional systems are a fascinating class of
+materials that could open alternative pathways to the manipulation of plasmon
+propagation and light-matter interactions. Here, we present a comprehensive
+study of the optical response in T$_d\,$-WTe$_2$ by means of density-functional
+and many-body perturbation theories. We show how monolayer WTe$_2$ with
+in-plane anisotropy sustains hyperbolic plasmon polaritons, which can be tuned
+via chemical doping and strain. The latter is able to extend the hyperbolic
+regime toward the near infrared with low losses. Moreover, with a moderate
+strain, WTe$_2$ can even be switched between elliptic and hyperbolic regimes.
+In addition, plasmons in WTe$_2$ are characterized by low losses owing to
+electron-phonon scattering, which is responsible for the temperature dependence
+of the plasmon line width. Interestingly, the temperature can also be utilized
+to tune the in-plane anisotropy of the WTe$_2$ optical response.",2006.12257v3
+2020-06-25,Spatial decomposition of magnetic anisotropy in magnets: application for doped Fe16N2,"We propose a scheme of decomposition of the total relativistic energy in
+solids to intra- and interatomic contributions. The method is based on a
+variation of the speed of light from its value in relativistic theory to
+infinity (a non-relativistic limit). As an illustration of the method, we
+tested such decomposition in the case of a spin-orbit interaction variation for
+decomposition of the magnetic anisotropy energy (MAE) in CoPt. We further
+studied the {\alpha}''-Fe16N2 magnet doped by Bi, Sb, Co and Pt atoms. It has
+been found that the addition of Pt atoms can enhance the MAE by as large as
+five times while Bi and Sb substitutions double the total MAE. Using the
+proposed technique we demonstrate the spatial distribution of these
+enhancements. Our studies also suggest that Sb, Pt and Co substitutions could
+be synthesized by experiments.",2006.14665v2
+2020-06-26,Initial fluctuations and power spectrum of flow anisotropies in relativistic heavy-ion collisions,"Flow has emerged as a crucial probe for the properties of the thermalized
+medium produced in relativistic heavy-ion collisions. The evolution of initial
+state fluctuations leaves imprints on the power spectrum of flow coefficients.
+Therefore flow coefficients are a crucial probe of initial state fluctuations
+arising from the parton distributions of the colliding nuclei. This has a very
+strong correspondence with the physics of power spectrum of cosmic microwave
+background radiation (CMBR) anisotropies which directly probes initial
+inflationary fluctuations. Much work has been done to probe these interesting
+interconnections, in particular, in developing techniques for the measurements
+of higher flow coefficients. We present a short review of these developments.
+The effect of initial magnetic field on these features will also be reviewed.
+All this acquires special importance in view of upcoming electron-ion collider
+which will directly probe initial parton distribution of the colliding nucleus.",2006.15177v2
+2020-07-02,The Imprint of Relativistic Particles on the Anisotropies of the Stochastic Gravitational-Wave Background,"The Stochastic Gravitational-Wave Background (SGWB) is expected to be a key
+observable for Gravitational-Wave (GW) interferometry. Its detection will open
+a new window on early Universe cosmology, on the astrophysics of compact
+objects and, as shown in this Letter, on the particle physics content of the
+Universe. In this Letter we show that, besides their effects on the Cosmic
+Microwave Background (CMB) and on Large Scale Structure (LSS), relativistic
+particles in the early Universe leave a clear imprint on the anisotropies of
+the SGWB. In particular we show that a change in the number of decoupled
+relativistic particles shifts the angular power spectrum of the SGWB, as both
+the Sachs-Wolfe (SW) and the Integrated Sachs-Wolfe (ISW) terms are affected.
+Being very large-angle effects, these lead to new testable predictions for
+future GW interferometers.",2007.01215v1
+2020-07-03,A Vanishingly Small Vector Mass from Anisotropy of Higher Dimensional Spacetime,"We consider five-dimensional massive vector-gravity theory which is based on
+the foliation preserving diffeomorphism and anisotropic conformal invariance.
+It does not have an intrinsic scale and the only relevant parameter is the
+anisotropic factor $z$ which characterizes the degree of anisotropy between the
+four-dimensional spacetime and the extra dimension. We assume that physical
+scale $M_*$ emerges as a consequence of spontaneous conformal symmetry breaking
+of vacuum solution. It is demonstrated that a very small mass for the vector
+particle compared to $M_*$ can be achieved with a relatively mild adjustment of
+the parameter $z$. At the same time, it is also observed that the motion along
+the extra dimension can be highly suppressed and the five-dimensional theory
+can be effectively reduced to four-dimensional spacetime.",2007.01551v2
+2020-07-06,Four-fold anisotropy of the parallel upper critical magnetic field in a pure layered d-wave superconductor at $T = 0$,"It is well known that a four-fold symmetry of the parallel upper critical
+magnetic field disappears in the Ginzburg-Landau (GL) region in
+quasi-two-dimensional (Q2D) $d$-wave superconductors. Therefore, it has been
+accurately calculated so far as a correction to the GL results, which is valid
+close to superconducting transition temperature and is expected to be stronger
+at low temperatures. As to the case $T=0$, some approximated methods have been
+used, which are good only for closed electron orbits and unappropriate for the
+open orbits which exist in a parallel magnetic field in Q2D superconductors.
+For the first time, we accurately calculate the four-fold anisotropy of the
+parallel upper critical magnetic field in a pure Q2D $d$-wave superconductor at
+$T=0$, where it has the highest possible value. Our results are applicable to
+Q2D $d$-wave high-Tc and organic superconductors.",2007.03061v1
+2020-07-07,Anisotropic Behavior of Excitons in Single Crystal α-SnS,"We investigate analytically the anisotropic dielectric properties of single
+crystal {\alpha}-SnS near the fundamental absorption edge by considering atomic
+orbitals. Most striking is the excitonic feature in the armchair- (b-) axis
+direction, which is particularly prominent at low temperatures. To determine
+the origin of this anisotropy, we perform first-principles calculations using
+the GW0 Bethe-Salpeter equation (BSE) including the electron-hole interaction.
+The results show that the anisotropic dielectric characteristics are a direct
+result of the natural anisotropy of p orbitals. In particular, this dominant
+excitonic feature originates from the py orbital at the saddle point in the
+{\Gamma}-Y region.",2007.03449v1
+2020-07-07,Anisotropy induced spin re-orientation in chemically-modulated amorphous ferrimagnetic films,"The ability to tune the competition between the in-plane and out-of-plane
+orientation of magnetization provides a means to construct thermal sensors with
+a sharp spin re-orientation transition at specific temperatures. We have
+observed such a tuneable, temperature driven spin re-orientation in
+structurally amorphous, ferrimagnetic rare earth-transition metal (RE-TM) alloy
+thin films using scanning transmission X-ray microscopy (STXM) and magnetic
+measurements. The nature of the spin re-orientation transition in FeGd can be
+fully explained by a non-equilibrium, nanoscale modulation of the chemical
+composition of the films. This modulation leads to a magnetic domain pattern of
+nanoscale speckles superimposed on a background of in-plane domains that form
+Laudau configurations in micron-scale patterned elements. It is this speckle
+magnetic structure that gives rise to a sharp two step-reversal mechanism that
+is temperature dependent. The possibility to balance competing anisotropies
+through the temperature opens opportunities to create and manipulate
+topological spin textures.",2007.03657v1
+2020-07-12,"Large magnetic anisotropy energy and robust half-metallic ferromagnetism in 2D MnXSe$_4$ (X = As, Sb)","In recent years, intrinsic two-dimensional (2D) magnetism aroused great
+interest because of its potential application in spintronic devices. However,
+low Curie temperature (\emph{T}$_c$) and magnetic anisotropy energy (MAE) limit
+its application prospects. Here, using first-principles calculations based on
+density-functional theory (DFT), we predicted a series of stable MnXSe$_4$
+(X=As, Sb) single-layer. The MAE of single-layer MnAsSe$_4$ and MnSbSe$_4$ was
+648.76 and 808.95 ${\mu}$eV per Mn atom, respectively. Monte Carlo (MC)
+simulations suggested the \emph{T}$_c$ of single-layer MnAsSe$_4$ and
+MnSbSe$_4$ was 174 and 250 K, respectively. The energy band calculation with
+hybrid Heyd-Scuseria-Ernzerhof (HSE06) function indicated the MnXSe$_4$ (X =
+As, Sb) were ferromagnetic (FM) half-metallic. Also it had 100\%
+spin-polarization ratio at the Fermi level. For MnAsSe$_4$ and MnSbSe$_4$, the
+spin-gap were 1.59 and 1.48 eV, respectively. These excellent magnetic
+properties render MnXSe$_4$ (X = As, Sb) promising candidate materials for 2D
+spintronic applications.",2007.05951v1
+2020-07-16,ENZ materials and Anisotropy: Enhancing Nonlinear Optical Interactions at the Nanoscale in Metal/Conducting-Oxide Multilayer Stacks,"Epsilon-near-zero materials are exceptional candidates for studying
+electrodynamics and nonlinear optical processes at the nanoscale. We
+demonstrate that by alternating a metal and a highly doped conducting-oxide,
+the epsilon-near-zero regime may be accessed resulting in an anisotropic,
+composite nanostructure that significantly enhances nonlinear interactions.
+Using two independent and different computation techniques we show that the
+structure can enhance the local field intensity by nearly two orders of
+magnitudes, in large part due to the onset of the effective anisotropy. The
+investigation of the multilayer nanostructure using a microscopic, hydrodynamic
+approach also sheds light on the roles of two competing contributions that are
+for the most part overlooked, but that can significantly modify linear and
+nonlinear responses of the structure: nonlocal effects, which blueshift the
+resulting resonance, and the hot electron nonlinearity, which redshifts the
+plasma frequency as the effective mass of free electrons increases as a
+function of incident power density. Finally, we show that, even in absence of
+second order bulk nonlinearity, second order nonlinear processes are also
+significantly enhanced by the layered structure.",2007.08312v1
+2020-07-17,Partial local entropy and anisotropy in deep weight spaces,"We refine a recently-proposed class of local entropic loss functions by
+restricting the smoothening regularization to only a subset of weights. The new
+loss functions are referred to as partial local entropies. They can adapt to
+the weight-space anisotropy, thus outperforming their isotropic counterparts.
+We support the theoretical analysis with experiments on image classification
+tasks performed with multi-layer, fully-connected and convolutional neural
+networks. The present study suggests how to better exploit the anisotropic
+nature of deep landscapes and provides direct probes of the shape of the minima
+encountered by stochastic gradient descent algorithms. As a by-product, we
+observe an asymptotic dynamical regime at late training times where the
+temperature of all the layers obeys a common cooling behavior.",2007.09091v3
+2020-07-20,Anisotropy fluctuation and correlation in central $α$-clustered $^{12}$C+$^{197}$Au collisions,"In the framework of a multi-phase transport model, fluctuation and
+correlation of the azimuthal anisotropies in $^{12}$C+$^{197}$Au collisions at
+$\sqrt{S_{NN}}$ = 200 GeV are explored. Properties of the initial eccentricity
+and final harmonic flow fluctuation resulted from $^{12}$C+$^{197}$Au
+collisions with Woods-Saxon configuration and triangular $\alpha$-clustering
+configurations of $^{12}$C are investigated via scaled variance, skewness and
+kurtosis. Comparisons are made between results from $\alpha$-clustered
+configurations and Woods-Saxon configuration. The triangular flow fluctuation
+is found to have particular sensitivity in distinguishing triangular
+$\alpha$-clustering structure of $^{12}$C. Furthermore, correlations between
+initial eccentricities and final flow harmonics are studied with strong
+multiplicity dependence observed for the correlation functions.",2007.10063v1
+2020-07-20,"Topology of many-body edge and extended quantum states in an open spin chain: 1/3--plateau, Kosterlitz-Thouless transition, and Luttinger liquid","Quantum many-body edge and extended magnon excitations from the 1/3 --
+plateau of the anisotropic Heisenberg model on an open AB$_2$ chain in a
+magnetic field $h$ are unveiled using the density matrix renormalization group
+and exact diagonalization. By tuning both the anisotropy and $h$ in the rich
+phase diagram, the edge states penetrate in the bulk, whose gap closes in a
+symmetry-protected topological Kosterlitz-Thouless transition. Also, we witness
+the squeezed chain effect, the breaking of the edge states degeneracy, and a
+topological change of the excitations from gapped magnons with quadratic
+long-wavelength dispersion to a linear spinon dispersion in the Luttinger
+liquid gapless phase as the anisotropy $\lambda$ approaches the critical point
+from the $\lambda>0$ side of the phase diagram.",2007.10414v1
+2020-07-26,Optical Anisotropy in Tellurene and its Janus Allotropes -- A first principle Study,"Here, we present first principle study of structural, electronic, and optical
+properties of pristine and janus tellurene allotropes using density functional
+theory (DFT). The $\alpha$, $\beta$, $\delta$, and $\eta$ allotrope of pristine
+tellurene exhibit indirect band gap while $\gamma$ and $\sigma$ allotropes are
+metallic. The bandgap shows tunability in janus tellurene compared to pristine
+tellurene. A metallic to semiconductor transition occurs in janus $\gamma$,
+$\sigma$ and its allotropes. Dirac cone-like interesting feature has been
+observed for pristine $\sigma$ tellurene which remains preserved with the
+opening in energy gap for janus allotrope. In optical properties, imaginary
+part dielectric function and electron energy loss spectra show a blue shift in
+janus tellurene as compared to pristine form. Static dielectric constant is
+tunable in janus tellurene. All allotropes of tellurene are optically active in
+UV-Vis region with optical anisotropy in all three directions. We believe that
+our findings will provide useful pointers in the experimental fabrication of
+devices based on janus tellurene.",2007.13066v1
+2020-07-28,Spin reorientation transition in an ultrathin Fe film on W(110) induced by Dzyaloshinsky-Moriya interactions,"Controlling the preferred direction of the magnetic moments is essential for
+the design of spintronic devices based on ultrathin films and heterostructures.
+As the film thickness or the temperature is increased, the easy anisotropy axis
+is typically reoriented from an out-of-plane direction preferred by surface and
+interface energy contributions to an in-plane alignment favored by the volume
+anisotropy terms. We study the temperature-driven spin reorientation transition
+in two atomic layers of Fe on W(110) using well-tempered metadynamics
+simulations based on a spin model parametrized by ab initio calculations and
+find that the transition only takes place in the presence of the
+Dzyaloshinsky--Moriya interaction (DMI). This demonstrates that the chiral DMI
+does not only differentiate between noncollinear spin structures of different
+rotational senses, but it also influences the magnetic orientation of collinear
+magnetic configurations.",2007.14116v2
+2020-08-02,Small-scale Tests of Inflation,"We investigate small-scale signatures of the inflationary particle content.
+We consider the case of a light spin-2 particle sourcing primordial
+gravitational waves by employing an effective field theory description. Upon
+allowing time-dependent sound speeds for the helicity modes, this setup
+delivers a blue tensor spectrum detectable, for example, by upcoming laser
+interferometers. Our focus is on the tensor non-Gaussianities that ensue from
+this field configuration. After characterising the bispectrum amplitude and
+shape-function at CMB scales, we move on to smaller scales where anisotropies
+induced in the tensor power spectrum by long-short modes coupling become the
+key handle on (squeezed) primordial non-Gaussianities. We identify the
+parameter space generating percent level anisotropies at scales soon to be
+probed by SKA and LISA.",2008.00452v2
+2020-08-04,Skyrmions in twisted van der Waals magnets,"Magnetic skyrmions in 2D chiral magnets are in general stabilized by a
+combination of Dzyaloshinskii-Moriya interaction and external magnetic field.
+Here, we show that skyrmions can also be stabilized in twisted moir\'e
+superlattices in the absence of an external magnetic field. Our setup consists
+of a 2D ferromagnetic layer twisted on top of an antiferromagnetic substrate.
+The coupling between the ferromagnetic layer and the substrate generates an
+effective alternating exchange field. We find a large region of skyrmion
+crystal phase when the length scales of the moir\'e periodicity and skyrmions
+are compatible. Unlike chiral magnets under magnetic field, skyrmions in
+moir\'e superlattices show enhanced stability for the easy-axis (Ising)
+anisotropy which can be essential to realize skyrmions since most van der Waals
+magnets possess easy-axis anisotropy.",2008.01294v2
+2020-08-04,Chern insulator transitions with Wilson fermions on a hyperrectangular lattice,"A $U(1)$ gauge theory coupled to a Wilson fermion on a $2+1$ dimensional
+cubic lattice is known to exhibit Chern insulator like topological transitions
+as a function of the the ratio $M/R$ where $M$ is the fermion mass and $R$ is
+the Wilson parameter. I show that, with $M$ and $R$ held fixed, a rectangular
+lattice with anisotropic lattice spacing can exhibit distinct topological
+phases as a function of the lattice anisotropy. As a consequence, a $2+1$
+dimensional lattice theory without any domain wall in the fermion mass can
+still exhibit chiral edge modes on a $1+1$ dimensional defect across which
+lattice spacing changes abruptly. Likewise, a domain wall in the fermion mass
+on a uniform rectangular lattice can exhibit discrete changes in the number and
+chirality of zero modes as a function of lattice anisotropy. The construction
+presented in this paper can be generalized to higher dimensional space-time
+lattices.",2008.01743v3
+2020-08-08,High-Frequency GaAs Optomechanical Bullseye Resonator,"The integration of optomechanics and optoelectronics in a single device opens
+new possibilities for developing information technologies and exploring
+fundamental phenomena. Gallium arsenide (GaAs) is a well-known material that
+can bridge the gap between the functionalities of optomechanical devices and
+optical gain media. Here, we experimentally demonstrate a high-frequency GaAs
+optomechanical resonator with a ring-type bullseye geometry that is
+unprecedented in this platform. We measured mechanical modes up to 3.4 GHz with
+quality factors of 4000 (at 77 K) and optomechanical coupling rates up to 39
+kHz at telecom wavelengths. Moreover, we investigated the material symmetry
+break due to elastic anisotropy and its impact on the mechanical mode spectrum.
+Finally, we assessed the temperature dependence of the mechanical losses and
+demonstrated the efficiency and anisotropy resilience of the bullseye anchor
+loss suppression, indicating that lower temperature operation may allow
+mechanical quality factors over $10^4$. Such characteristics are valuable for
+active optomechanics, coherent microwave-to-optics conversion via
+piezo-mechanics and other implementations of high-frequency oscillators in
+III-V materials.",2008.03429v2
+2020-08-10,A Striped Electron Fluid on (111) KTaO$_3$,"A recent study has revealed that the low carrier density electron gas (2DEG)
+induced at the interface of EuO and (111) KTaO$_3$ exhibits a broken symmetry
+phase with a strong in-plane anisotropy of the resistivity. We present a
+minimal tight binding model of this (111) 2DEG, including the large spin-orbit
+coupling from the Ta ions, which reveals a hexagonal Fermi surface with a
+highly enhanced 2$k_F$ electronic susceptibility. We argue that repulsive
+electronic interactions, together with a ferromagnetic EuO substrate, favor a
+magnetic stripe instability leading to a partially gapped Fermi surface. Such a
+stripe state, or its vestigial nematicity, could explain the observed transport
+anisotropy. We propose a $k\cdot p$ theory for the low energy $j=3/2$ states,
+which captures the key results from our tight-binding study, and further
+reveals the intertwined dipolar and octupolar modulations underlying this
+magnetic stripe order. We conclude by speculating on the relation of this
+stripe order to the superconductivity seen in this material.",2008.04337v1
+2020-08-20,Anisotropic ultrafast spin/valley dynamics in WTe2 films,"WTe2 Weyl semimetal hosts the natural broken inversion symmetry and strong
+spin orbit coupling, making it promising for exotic spin/valley dynamics within
+a picosecond timescale. Here, we unveil an anisotropic ultrafast spin/valley
+dynamics in centimeter-scale, single-crystalline Td-WTe2 films using a
+femtosecond pump-probe technique at room temperature. We observe a transient
+(~0.8 ps) intra-valley transition and a subsequent polarization duration (~5
+ps) during the whole spin/valley relaxation process. Furthermore, the
+relaxation exhibits the remarkable anisotropy of approximately six-fold and
+two-fold symmetries due to the intrinsic anisotropy along the crystalline
+orientation and the extrinsic matrix element effect, respectively. Our results
+offer a prospect for the ultrafast manipulation of spin/valleytronics in
+topological quantum materials for dissipationless high-speed spin/valleytronic
+devices.",2008.08785v2
+2020-08-21,"Growth and anisotropy evaluation of NbBiCh$_3$ (Ch = S, Se) misfit-layered superconducting single crystals","NbBiCh$_3$ (Ch = S, Se) misfit-layered superconducting single crystals were
+successfully grown using a CsCl/KCl flux for the first time. The obtained
+crystals had a well-developed habit parallel to the c-plane with a typical
+width of 1-2 mm and thickness of 10-40 um. The superconducting transition
+temperatures with zero resistivity of NbBiS$_3$ single crystals obtained from
+the nominal composition of Nb0.9Bi1.2S3 was 0.31 K, and that value of the
+NbBiSe$_3$ single crystals grown from the stoichiometry composition
+(NbBiSe$_3$) was 2.3 K. Sharp decreases in electric resistivity and magnetic
+susceptibility at approximately 3 K suggested a possible superconducting
+transition temperature of NbBiSe$_3$. The normal-state anisotropy values of
+grown NbBiS$_3$ and NbBiSe$_3$ single crystals were 2.2-2.4 and 1.5-1.6,
+respectively.",2008.09322v1
+2020-08-25,Anisotropy as a diagnostic test for distinct tensor network wavefunctions of integer and half-integer spin Kitaev quantum spin liquids,"Contrasting ground states of quantum magnets with the integer and
+half-integer spin moments are the manifestation of many-body quantum
+interference effects. In this work, we investigate the distinct nature of the
+integer and half-integer spin quantum spin liquids in the framework of the
+Kitaev's model on the honeycomb lattice. The models with arbitrary spin quantum
+numbers are not exactly solvable in contrast to the well-known quantum spin
+liquid solution of the spin-1/2 system. We use the tensor network wavefunctions
+for the integer and half-integer spin quantum spin liquid states to unveil the
+important difference between these states. We find that the distinct sign
+structures of the tensor network wavefunction for the integer and half-integer
+spin quantum spin liquids are responsible for completely different ground
+states in the spatially anisotropic limit. Hence the spatial anisotropy would
+be a useful diagnostic test for distinguishing these quantum spin liquid
+states, both in the numerical computations and experiments on real materials.
+We support this discovery via extensive numerics including the tensor network,
+DMRG, and exact diagonalization computations.",2008.10792v1
+2020-08-26,Revealing charge anisotropies in metal compounds via high-purity x-ray polarimetry,"Linear polarization analysis of hard x-rays is employed to probe electronic
+anisotropies in metal-containing complexes with very high selectivity. We use
+the pronounced linear dichroism of nuclear resonant x-ray scattering to
+determine electric field gradients in an iron(II) containing compound as they
+evolve during a temperature-dependent high-spin/low-spin phase transition. This
+method constitutes a novel approach to analyze changes in the electronic
+structure of metal-containing molecules as function of external parameters or
+stimuli. The polarization selectivity of the technique allows us to monitor
+defect concentrations of electronic valence states across phase transitions.
+This opens new avenues to trace electronic changes and their precursors that
+are connected to structural and electronic dynamics in the class of metal
+compounds ranging from simple molecular solids to biological molecules.",2008.11820v1
+2020-09-18,Schrödinger-type 2D coherent states of magnetized uniaxially strained graphene,"We revisit the uniaxially strained graphene immersed in a uniform homogeneous
+magnetic field orthogonal to the layer in order to describe the time evolution
+of coherent states build from a semi-classical model. We consider the symmetric
+gauge vector potential to render the magnetic field, and we encode the tensile
+and compression deformations on an anisotropy parameter $\zeta$. After solving
+the Dirac-like equation with an anisotropic Fermi velocity, we define a set of
+matrix ladder operators and construct electron coherent states as eigenstates
+of a matrix annihilation operator with complex eigenvalues. Through the
+corresponding probability density, we are able to study the anisotropy effects
+on these states on the $xy$-plane as well as their time evolution. Our results
+show clearly that the quasi-period of electron coherent states is affected by
+the uniaxial strain.",2009.08587v1
+2020-09-24,Phase diagram of multi-layer ferromagnet system with dipole-dipole interaction,"We investigate various magnetic configurations caused by the dipole-dipole
+interaction (DDI) in the thin-film magnet with the perpendicular anisotropy
+under the open boundary conditions. Two different approaches are simulated: one
+starts from a random magnetic configuration and decreases temperatures
+step-wisely; the other starts from the saturated out-of-plane ferromagnetic
+state to evaluate its metastability. As typical patterns of magnetic
+configuration, five typical configurations are found: an out-of-plane
+ferromagnetic, in-plane ferromagnetic, vortex, multi-domain, and canted
+multi-domain states. Notably, the canted multi-domain forms a concentric
+magnetic-domain-pattern with an in-plane vortex structure, resulting from the
+open boundary conditions. Concerning to the coercivity, a comparison of the
+magnetic configurations in both processes reveals that the out-of-plane
+ferromagnetic state exhibits metastability in the multi-domain state, while not
+in the vortex state. We also confirm that the so-called Neel-cap
+magnetic-domain-wall structure, which is originally discussed in the in-plane
+anisotropy system, appears at the multi-domain state.",2009.11574v1
+2020-09-24,Magnetic anisotropy and exchange paths for octa- and tetrahedrally coordinated Mn$^{2+}$ ions in the honeycomb multiferroic Mn$_2$Mo$_3$O$_8$,"We investigated the static and dynamic magnetic properties of the polar
+ferrimagnet Mn$_2$Mo$_3$O$_8$ in three magnetically ordered phases via
+magnetization, magnetic torque, and THz absorption spectroscopy measurements.
+The observed magnetic field dependence of the spin-wave resonances, including
+Brillouin zone-center and zone-boundary excitations, magnetization, and torque,
+are well described by an extended two-sublattice antiferromagnetic classical
+mean-field model. In this orbitally quenched system, the competing weak
+easy-plane and easy-axis single-ion anisotropies of the two crystallographic
+sites are determined from the model and assigned to the tetra- and octahedral
+sites, respectively, by ab initio calculations.",2009.11683v1
+2020-09-27,Theoretical study on the electric field effect on magnetism of Pd/Co/Pt thin films,"Based on first principles calculations we investigate the electronic and
+magnetic properties of Pt layers in Pd$(001)$/Co/Pt thin film structures
+exposed to an external electric field. Due to the Co underlayer, the surface Pt
+layers have induced moments that are modified by an external electric field.
+The field induced changes can be explained by the modified spin-dependent
+orbital hybridization that varies non-linearly with the field strength. We
+calculate the x-ray absorption and the x-ray magnetic circular dichroism
+spectra for an applied external electric field and examine its impact on the
+spectra in the Pt layer around the L$_{2}$ and L$_{3}$ edges. We also determine
+the layer dependent magneto-crystalline anisotropy and show that the anisotropy
+can be tuned easily in the different layers by the external electric field.",2009.12941v1
+2020-09-30,Designing of Magnetic MAB Phases for Energy Applications,"Based on high-throughput density functional theory calculations, we performed
+screening for stable magnetic MAB compounds and predicted potential strong
+magnets for permanent magnet and magnetocaloric applications. The
+thermodynamical, mechanical, and dynamical stabilities are systematically
+evaluated, resulting in 21 unreported compounds on the convex hull, and 434
+materials being metastable considering convex hull tolerance to be 100
+meV/atom. Analysis based on the Hume-Rothery rules revealed that the valence
+electron concentration and size factor difference are of significant importance
+in determining the stability, with good correspondence with the local atomic
+bonding. We found 71 compounds with the absolute value of magneto-crystalline
+anisotropy energy above 1.0 MJ/m$^3$ and 23 compounds with a uniaxial
+anisotropy greater than 0.4 MJ/m$^3$, which are potential gap magnets. Based on
+the magnetic deformation proxy, 99 compounds were identified as potential
+materials with interesting magnetocaloric performance.",2009.14543v1
+2020-10-05,"Theoretical study of current-induced domain wall motion in magnetic nanotubes with azimuthal domains, including Œrsted field and spin-transfer torques","We report a theoretical overview of the magnetic domain wall behavior under
+an electric current in infinitely-long nanotubes with azimuthal magnetization,
+combining the $1$D analytic model and micromagnetic simulations. We highlight
+effects that, besides spin-transfer torques already largely understood in flat
+strips, arise specifically in the tubular geometry: the \OErsted field and
+curvature-induced magnetic anisotropy resulting both from exchange and material
+growth. Depending on both the geometry of the tube and the strength of the
+azimuthal anisotropy, Bloch or N\'eel walls arise at rest, resulting in two
+regimes of motion largely dominated by either spin-transfer torques or the
+\OErsted field. We determine the Walker breakdown current in all cases, and
+highlight the most suitable parameters to achieve high domain wall speed.",2010.01966v1
+2020-10-13,Strong anisotropy of electron-phonon interaction in NbP probed by magnetoacoustic quantum oscillations,"In this study, we report on the observation of de Haas-van Alphen-type
+quantum oscillations (QO) in the ultrasound velocity of NbP as well as `giant
+QO' in the ultrasound attenuation in pulsed magnetic fields. The difference of
+the QO amplitude for different acoustic modes reveals a strong anisotropy of
+the effective deformation potential, which we estimate to be as high as
+$9\,\mathrm{eV}$ for certain parts of the Fermi surface. Furthermore, the
+natural filtering of QO frequencies and the tracing of the individual Landau
+levels to the quantum limit allows for a more detailed investigation of the
+Fermi surface of NbP as was previously achieved by means of analyzing QO
+observed in magnetization or electrical resistivity.",2010.06530v2
+2020-10-14,Fully anisotropic superconductivity with few Helmholtz Fermi-surface harmonics,"We present an alternative representation for the anisotropic Eliashberg
+equations of superconductivity, whose numerical solution yields an efficiency
+gain of several orders of magnitude with respect to the conventional
+representation in momentum space. Our method is a practical realization of a
+long-sought approach, whose essence is a linear transformation from regular
+${\bf k}$ space to a set of orthonormal functions defined as the solutions of
+the Helmholtz equation on the Fermi surface. In this way, all the anisotropy of
+the problem can be described by a handful of coefficients with built-in
+symmetry. We perform benchmark calculations on the gap anisotropy of MgB$_2$,
+and reproduce previous results at a remarkably reduced computational cost.
+Furthermore, we apply our methodology to efficiently determine the transition
+temperature of the compressed YH$_6$ hydride, obtaining very good agreement
+with recent experimental measurements. The simplification introduced by our
+method enables the high-throughput exploration of superconducting materials
+without having to resort to the isotropic approximation, and opens up
+possibilities towards first principles calculations of more advanced theories
+of superconductivity.",2010.06887v1
+2020-10-16,Hyperfine Couplings as a Probe of Orbital Anisotropy in Heavy Fermion Materials,"The transferred hyperfine interaction between nuclear and electron spins in
+an heavy fermion material depends on the hybridization between the $f$-electron
+orbitals and those surrounding a distant nucleus. In CeMIn$_5$ (M=Rh, Ir, Co),
+both the hyperfine coupling to the two indium sites as well as the crystalline
+electric field at the Ce are strongly dependent on the transition metal. We
+measure a series of CeRh$_{1-x}$Ir$_x$In$_5$ crystals and find that the
+hyperfine coupling reflects the orbital anisotropy of the ground state Ce 4$f$
+wavefunction. These findings provide direct proof that the localized to
+itinerant transition is dominated by hybridization out of the Ce-In plane in
+this system.",2010.08636v1
+2020-10-21,Anisotropy in Dijet Production in Exclusive and Inclusive Processes,"We investigate the effect of soft gluon radiations on the azimuthal angle
+correlation between the total and relative momenta of two jets in inclusive and
+exclusive dijet processes. We show that the final state effect induces a
+sizable $\cos(2\phi)$ anisotropy due to gluon emissions near the jet cones. The
+phenomenological consequences of this observation are discussed for various
+collider experiments, including diffractive processes in ultraperipheral $pA$
+and $AA$ collisions, inclusive and diffractive dijet production at the EIC, and
+inclusive dijet in $pp$ and $AA$ collisions at the LHC.",2010.10774v3
+2020-10-21,Learning Integrodifferential Models for Image Denoising,"We introduce an integrodifferential extension of the edge-enhancing
+anisotropic diffusion model for image denoising. By accumulating weighted
+structural information on multiple scales, our model is the first to create
+anisotropy through multiscale integration. It follows the philosophy of
+combining the advantages of model-based and data-driven approaches within
+compact, insightful, and mathematically well-founded models with improved
+performance. We explore trained results of scale-adaptive weighting and
+contrast parameters to obtain an explicit modelling by smooth functions. This
+leads to a transparent model with only three parameters, without significantly
+decreasing its denoising performance. Experiments demonstrate that it
+outperforms its diffusion-based predecessors. We show that both multiscale
+information and anisotropy are crucial for its success.",2010.10888v2
+2020-10-22,Anomalous Quantum Oscillations in Spin-3/2 Topological Semimetal YPtBi,"The proposed high-spin superconductivity in the half-Heusler compounds
+changes the landscape of superconductivity research. While superconducting
+instability is possible only in systems with quantum mechanically coherent
+quasiparticles, it has not been verified for any proposed high-spin Fermi
+surfaces. Here we report an observation of anomalous Shubnikov-de Haas effect
+in half-Heusler YPtBi, which is compatible with a coherent $j=3/2$ Fermi
+surface. The quantum oscillation (QO) signal in cubic YPtBi manifests extreme
+anisotropy upon rotation of the magnetic field from [100] to [110]
+crystallographic direction where the QO signal drastically vanishes near [110].
+This radical anisotropy for a cubic system cannot be explained by trivial
+scenarios for QO involving effective mass or impurity scattering, but it is
+naturally explained by the warping feature of the $j=3/2$ Fermi surface YPtBi.
+Our results prove the high-spin nature of the quasiparticle in the half-Heusler
+compounds, which makes the realization of the unprecedented high-spin
+superconductivity more plausible.",2010.12085v2
+2020-10-27,Demonstration of nanosecond operation in stochastic magnetic tunnel junctions,"Magnetic tunnel junctions operating in the superparamagnetic regime are
+promising devices in the field of probabilistic computing, which is suitable
+for applications like high-dimensional optimization or sampling problems.
+Further, random number generation is of interest in the field of cryptography.
+For such applications, a device's uncorrelated fluctuation time-scale can
+determine the effective system speed. It has been theoretically proposed that a
+magnetic tunnel junction designed to have only easy-plane anisotropy provides
+fluctuation rates determined by its easy-plane anisotropy field, and can
+perform on nanosecond or faster time-scale as measured by its
+magnetoresistance's autocorrelation in time. Here we provide experimental
+evidence of nanosecond scale fluctuations in a circular shaped easy-plane
+magnetic tunnel junction, consistent with finite-temperature coupled macrospin
+simulation results and prior theoretical expectations. We further assess the
+degree of stochasticity of such signal.",2010.14393v1
+2020-10-27,Wall-induced anisotropy effects on turbulent mixing in channel flow: A network-based analysis,"Turbulent mixing is studied in the Lagrangian framework with an approach
+based on the complex network formalism. We consider the motion of passive,
+noninertial particles inside a turbulent channel simulated at $Re_{\tau} =
+950$. The time-dependent network is built to evaluate the transfer of tracers
+between thin wall-parallel layers which partition the channel in the
+wall-normal direction. By doing so, we are able to assess the spatial and
+temporal complexities arising from turbulence dynamics and their influence on
+the mixing process. This approach highlights the effects of small-scale
+features of turbulent flow structures and also the larger scale effects
+determined by wall-induced anisotropy. Complex networks, coupled to the
+Lagrangian description of turbulence, are effective in providing novel insights
+into inhomogeneous turbulence and mixing.",2010.14408v1
+2020-10-30,"Spin-wave dispersion and exchange stiffness in Nd$_2$Fe$_{14}$B and $R$Fe$_{11}$Ti ($R$=Y, Nd, Sm) from first-principles calculations","We theoretically investigate spin-wave dispersion in rare-earth magnet
+compounds by using first-principles calculations and a method we call the
+reciprocal-space algorithm (RSA). The value of the calculated exchange
+stiffness for Nd$_2$Fe$_{14}$B is within the range of reported experimental
+values. We find that the exchange stiffness is considerably anisotropic when
+only short-range exchange couplings are considered, whereas inclusion of
+long-range couplings weakens the anisotropy. In contrast, $R$Fe$_{11}$Ti
+($R$=Y, Nd, Sm) shows large anisotropy in the exchange stiffness.",2010.16022v3
+2020-10-29,Crystal structures of dodecaborides: complexity in simplicity,"Analysis of the intriguing physical properties of the dodecaborides,
+$R$B$_{12}$, requires accurate data on their crystal structure. We show that a
+simple cubic model fits well with the atomic positions in the unit cell but
+cannot explain the observed anisotropy in the physical properties. The
+cooperative Jahn-Teller (JT) effect slightly violates the ideal metric of the
+cubic lattice and the symmetry of the electron density distribution in the
+lattice interstices. Theoretical models of the JT distortions of the boron
+framework are presented. Their correspondence to the electron-density
+distribution on the maps of Fourier syntheses obtained using x-ray data and
+explaining the previously observed anisotropy of conductive properties is
+demonstrated. The effect of boron isotope composition on the character of the
+lattice distortions is shown. We also discuss the application of the Einstein
+model for cations and the Debye model for the boron atoms to describe the
+dynamics of the crystal lattice.",2010.16239v1
+2020-11-02,Phase diagram of a three-dimensional dipolar model on a FCC lattice,"The magnetic phase diagram at zero external field of an ensemble of dipoles
+with uniaxial anisotropy on a FCC lattice is investigated from tempered Monte
+Carlo simulations. The uniaxial anisotropy is characterized by a random
+distribution of easy axes and its magnitude $\lambda_u$ is the driving force of
+disorder and consequently frustration. The phase diagram, separating the
+paramagnetic, ferromagnetic, quasi long range ordered ferromagnetic and
+spin-glass regions is thus considered in the temperature, $\lambda_u$ plane.
+This system is aimed at modeling the magnetic phase diagram of supracrystals of
+magnetic nanoparticles.",2011.00879v2
+2020-11-04,Anisotropy and stratification effects in the dynamics of fast rotating compressible fluids,"The primary goal of this paper is to develop robust methods to handle two
+ubiquitous features appearing in the modeling of geophysical flows: (i) the
+anisotropy of the viscous stress tensor, (ii) stratification effects. We focus
+on the barotropic Navier-Stokes equations with Coriolis and gravitational
+forces. Two results are the main contributions of the paper. Firstly, we
+establish a local well-posedness result for finite-energy solutions, via a
+maximal regularity approach. This method allows us to circumvent the use of the
+effective viscous flux, which plays a key role in the weak solutions theories
+of Lions-Feireisl and Hoff, but seems to be restricted to isotropic viscous
+stress tensors. Moreover, our approach is sturdy enough to take into account
+non constant reference density states; this is crucial when dealing with
+stratification effects. Secondly, we study the structure of the solutions to
+the previous model in the regime when the Rossby, Mach and Froude numbers are
+of the same order of magnitude. We prove an error estimate on the relative
+entropy between actual solutions and their approximation by a large-scale
+quasi-geostrophic flow supplemented with Ekman boundary layers. Our analysis
+holds for a large class of barotropic pressure laws.",2011.02411v1
+2020-11-06,Interface-driven electrical magnetochiral anisotropy in Pt/PtMnGa bilayers,"Nonreciprocal charge transport, which is frequently termed as electrical
+magnetochiral anisotropy (EMCA) in chiral conductors, touches the most
+important elements of modern condensed matter physics. Here, we have
+investigated the EMCA in Pt/PtMnGa (PMG) bilayers with the assitance of
+nonequilibrium fluctuation theorems. Large EMCA in the Pt/PMG bilayers can be
+attributed to nonreciprocal response of an interface-driven chiral transport
+channel. Due to the presence of large charge fluctuations for small current
+region, higher order EMCA coefficients should be added and they are all
+functions of current. A combination of asymmetrical electron scattering and
+spin-dependent scattering furnish the PMG thickness dependent chiral transport
+behaviors in Pt/PMG bilayers. The dramatically enhanced anomalous Hall angle of
+PMG further demonstrates the modified surface state properties by strong
+spin-orbit coupling.",2011.03244v3
+2020-11-18,Towards a general quasi-linear approach for the instabilities of bi-Kappa plasmas. Whistler instability,"Kappa distributions are ubiquitous in space and astrophysical poorly
+collisional plasmas, such as the solar wind, suggesting that microscopic and
+macroscopic properties of these non-equilibrium plasmas are highly conditioned
+by the wave-particle interactions. The present work addresses the evolution of
+anisotropic bi-Kappa (or bi-$\kappa$-)distributions of electrons triggering
+instabilities of electromagnetic electron-cyclotron (or whistler) modes. The
+new quasi-linear approach proposed here includes time variations of the
+$\kappa$ parameter during the relaxation of temperature anisotropy. Numerical
+results show that $\kappa$ may increase for short interval of times at the
+beginning, but then decreases towards a value lower than the initial one, while
+the plasma beta and temperature anisotropy indicate a systematic relaxation.
+Our results suggest that the electromagnetic turbulence plays an important role
+on the suprathermalization of the plasma, ultimately lowering the parameter
+$\kappa$. Even though the variation of $\kappa$ is in general negative ($\Delta
+\kappa <0$) this variation seems to depend of the initial conditions of
+anisotropic electrons, which can vary very much in the inner heliosphere.",2011.09108v2
+2020-11-18,Nanoparticle size threshold for magnetic agglomeration and associated hyperthermia performance,"The likelihood of magnetic nanoparticles to agglomerate is usually estimated
+through the ratio between magnetic dipole-dipole and thermal energies, thus
+neglecting the fact that, depending on the magnitude of the magnetic anisotropy
+constant ($K$), the particle moment may fluctuate internally and thus undermine
+the agglomeration process. Based on the comparison between the involved
+timescales, we study in this work how the threshold size for magnetic
+agglomeration ($d_{aggl}$) varies depending on the $K$ value. Our results
+suggest that small variations in $K$ -due to e.g. shape contribution-, might
+shift $d_{aggl}$ by a few nm. A comparison with the usual
+\textit{superparamagnetism} estimation is provided, as well as with the energy
+competition approach. In addition, based on the key role of the anisotropy in
+the hyperthermia performance, we also analyse the associated heating
+capability, as non-agglomerated particles would be of high interest for the
+application.",2011.09223v2
+2020-11-22,Built-in Electric-Field-Control of Magnetic Coupling in van der Waals semiconductors,"Electrical control of magnetism in a two-dimensional (2D) semiconductor is of
+great interest for emerging nanoscale low-dissipation spintronic devices. Here,
+we propose a general approach of tuning magnetic coupling and anisotropy of a
+van der Waals (vdW) 2D magnetic semiconductor via a built-in electric field
+generated by the adsorption of superatomic ions. Using first-principles
+calculations, we predict a significant enhancement of ferromagnetic (FM)
+coupling and a great change of magnetic anisotropy in 2D semiconductors when
+they are sandwiched between superatomic cations and anions. The magnetic
+coupling is directly affected by the built-in electric field, which lifts the
+energy levels of mediated ligands' orbitals and enhances the super-exchange
+interactions. These findings will be of interest for ionic gating controlled
+ferromagnets and magnetoelectronics based on vdW 2D semiconductors.",2011.10923v1
+2020-11-24,Prospects of Future CMB Anisotropy Probes for Primordial Black Holes,"Cascade of particles injected as Hawking Radiation from Primordial Black
+Holes (PBH) can potentially change the cosmic recombination history by ionizing
+and heating the intergalactic medium, which results in altering the anisotropy
+spectra of the Cosmic Microwave Background (CMB). In this paper, we study the
+expected sensitivity of several future CMB experiments in constraining the
+abundance of PBHs distributed in $10^{15}\sim10^{17}$ g mass window according
+to four mass functions: the monochromatic, log-normal, power-law and critical
+collapse models. Our result shows that future experiments, such as CMB-S4 and
+PICO, can improve current {\it{Planck}} bounds by about two orders of
+magnitudes. All regions in PBH parameter space that are allowed by current CMB
+data, including monochromatically distributed PBHs with mass heavier than $4
+\times 10^{16}$ grams, can be excluded by upcoming missions with high
+significance.",2011.12244v2
+2020-11-25,Antiferromagnetic magnon pseudospin: Dynamics and diffusive transport,"We formulate a theoretical description of antiferromagnetic magnons and their
+transport in terms of an associated pseudospin. The need and strength of this
+formulation emerges from the antiferromagnetic eigenmodes being formed from
+superpositions of spin-up and -down magnons, depending on the material
+anisotropies. Consequently, a description analogous to that of spin-1/2
+electrons is demonstrated while accounting for the bosonic nature of the
+antiferromagnetic eigenmodes. Introducing the concepts of a pseudospin chemical
+potential together with a pseudofield and relating magnon spin to pseudospin
+allows a consistent description of diffusive spin transport in
+antiferromagnetic insulators with any given anisotropies and interactions.
+Employing the formalism developed, we elucidate the general features of recent
+non-local spin transport experiments in antiferromagnetic insulators hosting
+magnons with different polarisations. The pseudospin formalism developed herein
+is valid for any pair of coupled bosons and is likely to be useful in other
+systems comprising interacting bosonic modes.",2011.12927v1
+2020-11-26,Optically-induced frequency up-conversion of the ferromagnetic resonance in an ultrathin garnet,"We perform ultrafast pump-probe measurements on a nanometer-thick crystalline
+Bi-doped yttrium iron garnet film with perpendicular magnetic anisotropy.
+Tuning the photon energy of the pump laser pulses above and below the
+material's bandgap, we trigger ultrafast optical and spin dynamics via both
+one- and two-photon absorption. Contrary to the common scenario, the
+optically-induced heating of the system induces an increase up to 20% of the
+ferromagnetic resonance frequency. We explain this unexpected result in terms
+of a photo-induced modification of the magnetic anisotropy, i.e. of the
+effective field, identifying the necessary conditions to observe this effect.
+Our results disclose the possibility to optically increase the magnetic
+eigenfrequency in nanometer-thick magnets.",2011.13403v1
+2020-12-02,Crystallographic Reconstruction Driven Modified Mechanical Properties in Anisotropic Rhenium Disulfides,"Atomic-scale investigation on mechanical behaviors is highly necessary to
+fully understand the fracture mechanics especially of brittle materials, which
+are determined by atomic-scale phenomena (e.g., lattice trapping). Here,
+exfoliated anisotropic rhenium disulfide (ReS2) flakes are used to investigate
+atomic-scale crack propagation depending on the propagation directions. While
+the conventional strain-stress curves exhibit a strong anisotropy depending on
+the cleavage direction of ReS2, but our experimental results show a reduced
+cleavage anisotropy due to the lattice reconstruction in [100] cracking with
+high resistance to fracture. In other words, [010] and [110] cracks with low
+barriers to cleavage exhibit the ultimate sharpness of the crack tip without
+plastic deformation, whereas [100] cracks drive lattice rotation on one side of
+the crack, leading to a non-flat grain boundary formation. Finally,
+crystallographic reconstruction associated with the high lattice randomness of
+two-dimensional materials drives to a modified cleavage tendency, further
+indicating the importance of atomic-scale studies for a complete understanding
+of the mechanics.",2012.01045v1
+2020-12-03,Constraining the initial stages of ultrarelativistic nuclear collisions,"It is frequently supposed that quark-gluon plasma created in heavy-ion
+collisions undergoes free streaming at early times. We examine this issue based
+on the assumption that a universal attractor dominates the dynamics already at
+the earliest stages, which offers a way to connect the initial state with the
+start of the hydrodynamic expansion in an approximate but conceptually
+transparent fashion. We demonstrate that the centrality dependence of the
+measured particle multiplicities can be used to quantitatively constrain the
+pressure anisotropy and find that it strongly depends on the model of the
+initial energy deposition. As an illustration, we compare three initial state
+models and show that they predict rather different early-time values of the
+pressure anisotropy. This strongly suggests that assuming free streaming prior
+to hydrodynamization is not necessarily compatible with a generic initial state
+model and that features of the pre-hydrodynamic flow need to be matched with
+the model of the initial state.",2012.02184v3
+2020-12-11,Anisotropies in Compressible MHD Turbulence: Probing Magnetic Fields and Measuring Magnetization,"Probing magnetic fields in the interstellar medium (ISM) is notoriously
+challenging. Motivated by the modern theories of magnetohydrodynamic (MHD)
+turbulence and turbulence anisotropy, we introduce the Structure-Function
+Analysis (SFA) as a new approach to measure the magnetic field orientation and
+estimate the magnetization. We analyze the statistics of turbulent velocities
+in three-dimensional compressible MHD simulations through the second-order
+structure functions in both local and global reference frames. In the
+sub-Alfvenic turbulence with the magnetic energy larger than the turbulent
+energy, the SFA of turbulent velocities measured in the directions
+perpendicular and parallel to the magnetic field can be significantly
+different. Their ratio has a power-law dependence on the Alfven Mach number
+$M_A$, which is inversely proportional to the magnetic field strength. We
+demonstrate that the anisotropic structure functions of turbulent velocities
+can be used to estimate both the orientation and strength of magnetic fields.
+With turbulent velocities measured using different tracers, our approach can be
+generally applied to probing the magnetic fields in the multi-phase
+interstellar medium.",2012.06039v2
+2020-12-23,Interplay of crystal thickness and in-plane anisotropy and evolution of quasi-one dimensional electronic character in ReSe$_{2}$,"We study the valence band structure of ReSe$_{2}$ crystals with varying
+thickness down to a single layer using nanoscale angle-resolved photoemission
+spectroscopy and density functional theory. The width of the top valence band
+in the direction perpendicular to the rhenium chains decreases with decreasing
+number of layers, from 280 meV for the bulk to 61 meV for monolayer. This
+demonstrates increase of in-plane anisotropy induced by changes in the
+interlayer coupling and suggests progressively more one-dimensional character
+of electronic states in few-layer rhenium dichalcogenides.",2012.12659v3
+2020-12-23,Inertial effects on the Brownian gyrator,"The recent interest into the Brownian gyrator has been confined chiefly to
+the analysis of Brownian dynamics both in theory and experiment despite the
+applicability of general cases with definite mass. Considering mass explicitly
+in the solution of the Fokker--Planck equation and Langevin dynamics
+simulations, we investigate how inertia can change the dynamics and energetics
+of the Brownian gyrator. In the Langevin model, the inertia reduces the
+nonequilibrium effects by diminishing the declination of the probability
+density function and the mean of a specific angular momentum, $j_\theta$, as a
+measure of rotation. Another unique feature of the Langevin description is that
+rotation is maximized at a particular anisotropy while the stability of the
+rotation is minimized at a particular anisotropy or mass. Our results suggest
+that the Langevin dynamics description of the Brownian gyrator is intrinsically
+different from that with Brownian dynamics. In addition, $j_\theta$ is proven
+to be essential and convenient for estimating stochastic energetics such as
+heat currents and entropy production even in the underdamped regime.",2012.12713v2
+2020-12-23,Electric manipulation of domain walls in magnetic Weyl semimetals via the axial anomaly,"We show how the axial (chiral) anomaly induces a spin torque on the
+magnetization in magnetic Weyl semimetals. The anomaly produces an imbalance in
+left- and right-handed chirality carriers when non-orthogonal electric and
+magnetic fields are applied. Such imbalance generates a spin density which
+exerts a torque on the magnetization, the strength of which can be controlled
+by the intensity of the applied electric field. We show how this results in an
+electric control of the chirality of domain walls, as well as in an improvement
+of the domain wall dynamics, by delaying the onset of the Walker breakdown. The
+measurement of the electric field mediated changes in the domain wall chirality
+would constitute a direct proof of the axial anomaly. Additionally, we show how
+quantum fluctuations of electronic Fermi arc states bound to the domain wall
+naturally induce an effective magnetic anisotropy, allowing for high domain
+wall velocities even if the intrinsic anisotropy of the magnetic Weyl semimetal
+is small.",2012.12785v2
+2020-12-28,Gravitational collapse of anisotropic stars,"We study the gravitational collapse of a spherically symmetric anisotropic
+relativistic star within Einstein theory of gravity making use of one of our
+recently developed collapsing stellar models [{\it Astrophys. Space Sci.}
+{\bf361} 99 (2016)]. The final state of continual gravitational collapse of a
+massive star under regular initial conditions is analyzed in terms of the
+formation of black holes. To study the evolution of an anisotropic star
+undergoing gravitational collapse, it is assumed that the dissipation process
+happens in the form of radial heat-flux. The interior space-time is described
+by static metric matched at the boundary with Vaidya metric that describes the
+exterior to the radiating star. The initial static configuration is described
+by the relativistic solution obtained by Paul and Deb [{\it Astrophys. Space
+Sci.} {\bf354} 421 (2014)]. The impact of anisotropy on the dynamical
+gravitational collapse of a massive star is studied. The relativistic causal
+heat transport equation of the Maxwell-Cattaneo equation is utilized to show
+the dependence of anisotropy on the temperature profile of the collapsing
+system.",2012.14084v1
+2020-12-30,RF signal detector and energy harvester based on a spin-torque diode with perpendicular magnetic anisotropy,"We demonstrate theoretically that in a spintronic diode (SD), having a free
+magnetic layer with perpendicular magnetic anisotropy of the first and second
+order and no external bias magnetic field, the out-of-plane regime of
+magnetization precession can be excited by sufficiently large (exceeding a
+certain threshold) RF signals with the frequencies <~250 MHz. We also show that
+such a device can operate as a broadband energy harvester capable of converting
+incident RF power into a DC power with the conversion efficiency of ~5%. The
+developed analytical theory of the bias-free SD operation can be used for the
+optimization of high-efficiency RF detectors and energy harvesters based on
+SDs.",2012.15107v1
+2020-12-30,"Anisotropic magnetic interactions in hexagonal AB-stacked kagome lattice structures: Applications to $\mathrm{Mn}_3\mathrm{X}$ ($\mathrm{X}$ = $\mathrm{Ge}$, $\mathrm{Sn}$, $\mathrm{Ga}$) compounds","$\mathrm{Mn}_3\mathrm{X}$ compounds in which the magnetic $\mathrm{Mn}$ atoms
+form AB-stacked kagome lattices have received a tremendous amount of attention
+since the observation of the anomalous Hall effect in
+$\mathrm{Mn}_3\mathrm{Ge}$ and $\mathrm{Mn}_3\mathrm{Sn}$. Although the
+magnetic ground state has been known for some time to be an inverse triangular
+structure with an induced in-plane magnetic moment, there have been several
+controversies about the minimal magnetic Hamiltonian. We present a general
+symmetry-based model for these compounds that includes a previously unreported
+interplane Dzyaloshinskii-Moriya interaction, as well as anisotropic exchange
+interactions. The latter are shown to compete with the single-ion anisotropy
+which strongly affects the ground state configurations and elementary spin-wave
+excitations. Finally, we present the calculated elastic and inelastic neutron
+scattering intensities and point to experimental assessment of the types of
+magnetic anisotropy in these compounds that may be important.",2012.15280v2
+2021-01-04,Spacing Homogenization in Lamellar Eutectic Arrays with Anisotropic Interphase Boundaries,"We analyze the effect of interphase boundary anisotropy on the dynamics of
+lamellar eutectic solidification fronts, in the limit that the lamellar spacing
+varies slowly along the envelope of the front. In the isotropic case, it is
+known that the spacing obeys a diffusion equation, which can be obtained
+theoretically by making two assumptions: (i) the lamellae always grow normal to
+the large-scale envelope of the front, and (ii) the Jackson-Hunt law that links
+lamellar spacing and front temperature remains locally valid. For anisotropic
+boundaries, we replace hypothesis (i) by the symmetric pattern approximation,
+which has recently been found to yield good predictions for lamellar growth
+direction in presence of interphase anisotropy. We obtain a generalized
+Jackson-Hunt law for tilted lamellae, and an evolution equation for the
+envelope of the front. The latter contains a propagative term if the initial
+lamellar array is tilted with respect to the direction of the temperature
+gradient. However, the propagation velocity of the propagative wave modes are
+found to be small, so that the dynamics of the front can be reasonably
+described by a diffusion equation with a diffusion coefficient that is modified
+with respect to the isotropic case.",2101.01040v1
+2021-01-07,Giant interfacial induced Dzyaloshinskii-Moriya interaction in polycrystalline Co/Pt multilayers,"Multilayers of heavy metals and ferromagnets are the basis for the formation
+of various structures with inhomogeneous chiral magnetic distributions. The
+most informative method for studying magnetic states in such structures with a
+high spatial resolution is Lorentz transmission electron microscopy (L-TEM).
+Here, we report on the observation of chiral N\'eel domain walls by means of
+L-TEM in Co/Pt multilayers with perpendicular magnetic anisotropy. We explain
+the existence of chiral N\'eel internal structure due to the overcritical,
+giant interfacial induced Dzyaloshinskii-Moriya interaction. Our results are
+confirmed by micromagnetic modeling, which allows taking into account the
+effect of local inhomogeneity of the magnetic anisotropy of polycrystalline
+films on formation of spin textures.",2101.02460v1
+2021-01-10,Crystallization of anisotropic colloids with a Yukawa potential,"Crystallization in a dense suspension of anisotropic spherical colloidal
+particles with a Yukawa potential is numerically investigated in a
+two-dimensional plane. It is found that a strong anisotropy can hinder the
+particles from crystallizing, while a weak anisotropy but super-strong coupling
+facilitates colloids to freeze into a hexagonal crystal. Different criterions
+are employed to describe the phase transition, one can find that a competition
+between anisotropic degree and coupling strength shall widened the transition
+region in the phase diagram, where the heterogeneous structures coexist, which
+render as a quasi-platform stretched across the probability distribution curve
+of the local order parameter. Our study maybe helpful for the experiments
+relating to the crystallizing behavior in statistical physics, materials
+science and biophysical systems.",2101.03551v2
+2021-01-17,Surface-Wave Propagation on Non-Hermitian Metasurfaces with Extreme Anisotropy,"Electromagnetic metasurfaces enable the advanced control of surface-wave
+propagation by spatially tailoring the local surface reactance. Interestingly,
+tailoring the surface resistance distribution in space provides new, largely
+unexplored degrees of freedom. Here, we show that suitable spatial modulations
+of the surface resistance between positive (i.e., loss) and negative (i.e.,
+gain) values can induce peculiar dispersion effects, far beyond a mere
+compensation. Taking inspiration from the parity-time symmetry concept in
+quantum physics, we put forward and explore a class of non-Hermitian
+metasurfaces that may exhibit extreme anisotropy mainly induced by the
+gain-loss interplay. Via analytical modeling and full-wave numerical
+simulations, we illustrate the associated phenomenon of surface-wave
+canalization, explore nonlocal effects and possible departures from the ideal
+conditions, and address the feasibility of the required constitutive
+parameters. Our results suggest intriguing possibilities to dynamically
+reconfigure the surface-wave propagation, and are of potential interest for
+applications to imaging, sensing and communications.",2101.06641v1
+2021-01-18,Manipulating the anisotropic phase separation in strained VO2 epitaxial films by nanoscale ion-implantation,"Manipulating the strain induced poly-domains and phase transition in
+correlated oxide material are important for high performance devices
+fabrication. Though the electronic transport in the strained oxide film at
+macroscopic scales can be directly measured, the anisotropic electronic state
+and the controllable phase separation cross the insulator-to-metal transition
+within nanoscale size are still elusive. Here, we selected VO2 crystal film as
+a prototypical oxide and achieved the manipulation of anisotropy electronic
+phase separation via injecting He+ nanobeam into VO2 film at room temperature.
+In addition, this nanoscale phase separation was directly visualized by
+infrared near-field imaging measurements, showing the pronounced and unique
+cR-axis dependent anisotropy on VO2 surface. Our results offered new insights
+towards understanding the anisotropic nanoscale phase separation in strained
+metal oxide films.",2101.07093v2
+2021-01-22,New interpretation of the Extended Geometric Deformation in Isotropic Coordinates,"We study the particular case in which Extended Geometric Deformation does
+consists of consecutive deformations of temporal and spatial components of the
+metric, in Schwarzschild-like and isotropic coordinates. In the latter, we
+present two inequivalent ways to perform this 2-steps GD. This was done in such
+a way that the method may be applied to different seed solutions. As an
+example, we use Tolman IV as seed solution, in order to obtain two inequivalent
+physical solutions with anisotropy in the pressures in Schwarzschild-like
+coordinates. In the isotropic sector, we obtained four different solutions with
+anisotropy in the pressures that satisfy physical acceptability conditions,
+using Gold III as seed solution.",2101.09148v4
+2021-01-25,Formation of solid-state dendrites under the influence of coherency stresses: A diffuse interface approach,"In this paper, we have formulated a phase-field model based on the
+grand-potential functional for the simulation of precipitate growth in the
+presence of coherency stresses. In particular, we study the development of
+dendrite-like patterns arising out of diffusive instabilities during the growth
+of a precipitate in a supersaturated matrix. Here, we characterize the role of
+elastic energy anisotropy and its strength on the selection of a dendrite tip
+radius and velocity. We find that there is no selection of a unique tip shape
+as observed in the case of solidification, and the selection constant
+$\sigma^{*}=2d_0D/R_{tip}^{2}V_{tip}$ increases linearly with simulation time
+for all the simulation conditions (where $R_{tip}$ and $V_{tip}$ are the tip
+radius and velocity). Therefore, structures derived in solid-state in the
+presence of elastic anisotropy may only be referred to as dendrite-like.",2101.09964v1
+2021-01-26,Stabilizing current-driven steady flows of 180$^{\circ}$ domain walls in spin valves by interfacial Dzyaloshinskii-Moriya interaction,"Modulations of interfacial Dzyaloshinskii-Moriya interaction (iDMI) on
+current-driven dynamics of 180$^{\circ}$ domain walls (180DWs) in long and
+narrow spin valves (LNSVs) with heavy-metal caplayers are systematically
+investigated. We focus on LNSVs with in-plane magnetic anisotropy in their free
+layers. For planar-transverse polarizers (pinned layers of LNSVs), the Walker
+breakdown can be postponed considerably (practical infinity) by iDMI. More
+interestingly, the originally unstable traveling mode is also stabilized by
+iDMI with high saturation velocity thus serves as fast carrier of information.
+For parallel polarizers, the Walker limit is increased and the corresponding
+modifications of iDMI to wall velocity in both steady and precessional flows of
+180DWs are provided. For perpendicular polarizers, precessional flow of 180DWs
+is absent due to the stability of stationary mode beyond the modified Walker
+limit. For LNSVs with perpendicular magnetic anisotropy in their free layers,
+similar results are obtained. Our findings open new possibilities for
+developing magnetic nanodevices based on 180DW propagation with low energy
+consumption and high robustness.",2101.10590v1
+2021-01-29,Magnetization Reversal Mechanism in Exchange-Biased Spring-like Thin-Film Composite,"Development of modern spintronic devices requires materials exhibiting
+specific magnetic effects. In this paper, we investigate a magnetization
+reversal mechanism in a [Co/Pdx]7/CoO/[Co/Pdy]7 thin-film composite where an
+antiferromagnet is sandwiched between a hard and a soft ferromagnets with
+different coercivities. The antiferromagnet/ferromagnet interfaces give rise to
+the exchange bias effect. The application of soft and hard ferromagnetic films
+causes exchange-spring-like behavior while the choice of the Co/Pd multilayers
+provides large out-of-plane magnetic anisotropy. We observed that the magnitude
+and the sign of the exchange bias anisotropy field are related to the
+arrangement of the magnetic moments in the antiferromagnetic layer. This
+ordering is induced by the spin orientation present in neighboring
+ferromagnetic films which is, in turn, dependent on the orientation and
+strength of the external magnetic field.",2101.12495v1
+2021-01-30,Cosmic-ray current-driven instabilities -- revisiting environmental conditions,"The growth of magneto-hydrodynamic fluctuations relevant to cosmic ray
+confinement in and near their sources, and the effects of local plasma
+conditions is revisited. We consider cases where cosmic rays penetrate a medium
+which may contain a fraction of neutral particles, and explore the possible
+effects of high-order cosmic-ray anisotropies. An algorithm for calculating the
+dispersion relation for arbitrary distributions, and anisotropies is presented,
+and a general solution for power-law cosmic-ray distributions is provided.
+Implications for the resulting instabilities near to strong Galactic cosmic-ray
+sources are discussed. We argue that cosmic-ray streaming in weakly ionised
+plasmas eliminates the need for the existence of an evanescent band in the
+dispersion relation, a conclusion which may be confirmed by gamma-ray
+observations. The necessity for additional multi-scale numerical simulations is
+highlighted, as understanding the non-linear behaviour is crucial.",2102.00334v1
+2021-02-03,Parton collisional effect on the conversion of geometry eccentricities into momentum anisotropies in relativistic heavy-ion collisions,"We explore parton collisional effects on the conversion of geometry
+eccentricities into azimuthal anisotropies in Pb+Pb collisions at
+$\sqrt{s_{NN}}$ = 5.02 TeV using a multi-phase transport model. The initial
+eccentricity $\varepsilon_{n}$ (n = 2,3) and flow harmonics $v_{n}$ (n = 2,3)
+are investigated as a function of the number of parton collisions ($N_{coll}$)
+during the source evolution of partonic phase. It is found that partonic
+collisions leads to generate elliptic flow $v_{2}$ and triangular flow $v_{3}$
+in Pb+Pb collisions. On the other hand, partonic collisions also result in an
+evolution of the eccentricity of geometry. The collisional effect on the flow
+conversion efficiency is therefore studied. We find that the partons with
+larger $N_{coll}$ show a lower flow conversion efficiency, which reflect
+differential behaviors with respect to $N_{coll}$. It provides an additional
+insight into the dynamics of the space-momentum transformation during the QGP
+evolution from a transport model point of view.",2102.01872v1
+2021-02-05,Tip-induced domain protrusion in ferroelectric films with in-plane polarization,"Charge manipulation and fabrication of stable domain patterns in
+ferroelectric materials by scanning probe microscopy open up broad avenues for
+the development of tunable electronics. Harnessing the polarization energy and
+electrostatic forces with specific geometry of the system enables producing the
+nanoscale domains by-design. Along with that, domain engineering requires
+mastery of underlying physical mechanisms that govern the domain formation.
+Here, we present a theoretical description of the domain formation by a
+scanning probe microscopy tip in a ferroelectric film with strong in-plane
+anisotropy of polarization. We demonstrate that local charge injection produces
+wedge-shaped domains that propagate along the anisotropy axis, whereas the
+tip-written lines of charge generate a comb-like domain structure. The results
+of our calculations agree with earlier experimental observations and allow for
+the optimization of the targeted domain structures.",2102.03174v1
+2021-02-07,Spinterface Induced Modification in Magnetic Properties in Co40Fe40B20/Fullerene Bilayers,"Organic semiconductor/ferromagnetic bilayer thin films can exhibit novel
+properties due to the formation of the spinterface at the interface.
+Buckminsterfullerene (C60) has been shown to exhibit ferromagnetism at the
+interface when it is placed next to a ferromagnet (FM) such as Fe or Co.
+Formation of spinterface occurs due to the orbital hybridization and spin
+polarized charge transfer at the interface. In this work, we have demonstrated
+that one can enhance the magnetic anisotropy of the low Gilbert damping alloy
+CoFeB by introducing a C60 layer. We have shown that anisotropy increases by
+increasing the thickness of C60 which might be a result of the formation of
+spinterface. However, the magnetic domain structure remains same in the bilayer
+samples as compared to the reference CoFeB film.",2102.03914v4
+2021-02-08,"Axisymmetric dynamo action produced by differential rotation, with anisotropic electrical conductivity and anisotropic magnetic permeability","The effect on dynamo action of an anisotropic electrical conductivity
+conjugated to an anisotropic magnetic permeability is considered. Not only is
+the dynamo fully axisymmetric, but it requires only a simple differential
+rotation, which twice challenges the well-established dynamo theory. Stability
+analysis is conducted entirely analytically, leading to an explicit expression
+of the dynamo threshold. The results show a competition between the anisotropy
+of electrical conductivity and that of magnetic permeability, the dynamo effect
+becoming impossible if the two anisotropies are identical. For isotropic
+electrical conductivity, Cowling's neutral point argument does imply the
+absence of an azimuthal component of current density, but does not prevent the
+dynamo effect as long as the magnetic permeability is anisotropic.",2102.04343v1
+2021-02-18,Two-dimensional easy-plane SU$(3)$ magnet with the transverse field: Anisotropy-driven multicriticality,"The two-dimensional easy-plane SU$(3)$ magnet subjected to the transverse
+field was investigated with the exact-diagonalization method. So far, as to the
+$XY$ model (namely, the easy-plane SU$(2)$ magnet), the transverse-field-driven
+order-disorder phase boundary has been investigated with the
+exact-diagonalization method, and it was claimed that the end-point singularity
+(multicriticality) at the $XX$-symmetric point does not accord with
+large-$N$-theory's prediction. Aiming to reconcile the discrepancy, we extend
+the internal symmetry to the easy-plane SU$(3)$ with the anisotropy parameter
+$\eta$, which interpolates the isotropic ($\eta=0$) and fully anisotropic
+($\eta=1$) cases smoothly. As a preliminary survey, setting $\eta=1$, we
+analyze the order-disorder phase transition through resorting to the fidelity
+susceptibility $\chi_F$, which exhibits a pronounced signature for the
+criticality. Thereby, with $\eta$ scaled carefully, the $\chi_F$ data are cast
+into the crossover-scaling formula so as to determine the crossover exponent
+$\phi$, which seems to reflect the extension of the internal symmetry group to
+SU(3).",2102.09083v1
+2021-02-18,"Voltage control of skyrmions: creation, annihilation and zero-magnetic field stablization","Voltage manipulation of skyrmions is a promising path towards low-energy
+spintronic devices. Here, voltage effects on skyrmions in a GdOx/Gd/Co/Pt
+heterostructure are observed experimentally. The results show that the skyrmion
+density can be both enhanced and depleted by the application of an electric
+field, along with the ability, at certain magnetic fields to completely switch
+the skyrmion state on and off. Further, a zero magnetic field skyrmion state
+can be stablized under a negative bias voltage using a defined voltage and
+magnetic field sequence. The voltage effects measured here occur on a
+few-second timescale, suggesting an origin in voltage-controlled magnetic
+anisotropy rather than ionic effects. By investigating the skyrmion nucleation
+rate as a function of temperature, we extract the energy barrier to skyrmion
+nucleation in our sample. Further, micromagnetic simulations are used to
+explore the effect of changing the anisotropy and Dzyaloshinskii-Moriya
+interaction on skyrmion density. Our work demonstrates the control of skyrmions
+by voltages, showing functionalities desirable for commercial devices.",2102.09178v1
+2021-02-22,Robust formation of nanoscale magnetic skyrmions in easy-plane thin film multilayers with low damping,"We experimentally demonstrate the formation of room-temperature skyrmions
+with radii of about 25\,nm in easy-plane anisotropy multilayers with
+interfacial Dzyaloshinskii-Moriya interaction (DMI). We detect the formation of
+individual magnetic skyrmions by magnetic force microscopy and find that the
+skyrmions are stable in out-of-plane fields up to about 200 mT. We determine
+the interlayer exchange coupling as well as the strength of the interfacial
+DMI. Additionally, we investigate the dynamic microwave spin excitations by
+broadband magnetic resonance spectroscopy. From the uniform Kittel mode we
+determine the magnetic anisotropy and low damping $\alpha_{\mathrm{G}} < 0.04$.
+We also find clear magnetic resonance signatures in the non-uniform (skyrmion)
+state. Our findings demonstrate that skyrmions in easy-plane multilayers are
+promising for spin-dynamical applications.",2102.11117v1
+2021-02-23,A fully-kinetic model for orphan gamma-ray flares in blazars,"Blazars emit a highly-variable non-thermal spectrum. It is usually assumed
+that the same non-thermal electrons are responsible for the IR-optical-UV
+emission (via synchrotron) and the gamma-ray emission (via inverse Compton).
+Hence, the light curves in the two bands should be correlated. Orphan gamma-ray
+flares (i.e., lacking a luminous low-frequency counterpart) challenge our
+theoretical understanding of blazars. By means of large-scale two-dimensional
+radiative particle-in-cell simulations, we show that orphan gamma-ray flares
+may be a self-consistent by-product of particle energization in turbulent
+magnetically-dominated pair plasmas. The energized particles produce the
+gamma-ray flare by inverse Compton scattering an external radiation field,
+while the synchrotron luminosity is heavily suppressed since the particles are
+accelerated nearly along the direction of the local magnetic field. The ratio
+of inverse Compton to synchrotron luminosity is sensitive to the initial
+strength of turbulent fluctuations (a larger degree of turbulent fluctuations
+weakens the anisotropy of the energized particles, thus increasing the
+synchrotron luminosity). Our results show that the anisotropy of the
+non-thermal particle population is key to modeling the blazar emission.",2102.11770v1
+2021-02-26,Effective anisotropy of periodic acoustic and elastic composites,"The propagation of acoustic or elastic waves in artificial crystals,
+including the case of phononic and sonic crystals, is inherently anisotropic.
+As is known from the theory of periodic composites, anisotropy is directly
+dictated by the space group of the unit cell of the crystal and the rank of the
+elastic tensor. Here, we examine effective velocities in the long wavelength
+limit of periodic acoustic and elastic composites as a function of the
+direction of propagation. We derive explicit and efficient formulas for
+estimating the effective velocity surfaces, based on second-order perturbation
+theory, generalizing the Christofell equation for elastic waves in solids. We
+identify strongly anisotropic sonic crystals for scalar acoustic waves and
+strongly anisotropic phononic crystals for vector elastic waves. Furthermore,
+we observe that under specific conditions, quasi-longitudinal waves can be made
+much slower than shear waves propagating in the same direction.",2102.13506v1
+2021-02-27,Covalent 2D Cr$_2$Te$_3$ ferromagnet,"To broaden the scope of van der Waals 2D magnets, we report the synthesis and
+magnetism of covalent 2D magnetic Cr$_2$Te$_3$ with a thickness down to
+one-unit-cell. The 2D Cr$_2$Te$_3$ crystals exhibit robust ferromagnetism with
+a Curie temperature of 180 K, a large perpendicular anisotropy of 7*105 J m-3,
+and a high coercivity of ~ 4.6 kG at 20 K. First-principles calculations
+further show a transition from canted to collinear ferromagnetism, a transition
+from perpendicular to in-plane anisotropy, and emergent half-metallic behavior
+in atomically-thin Cr$_2$Te$_3$, suggesting its potential application for
+injecting carriers with high spin polarization into spintronic devices.",2103.00339v1
+2021-03-01,Multi-Messenger Astrophysics with the Cosmic Neutrino Background,"The massive neutrinos of the Cosmic Neutrino Background (C$\nu$B) are
+fundamental ingredients of the radiation-dominated early universe and are
+important non-relativistic probes of the large-scale structure formation in the
+late universe. The dominant source of anisotropies in the neutrino flux
+distribution on the sky are highly amplified integrals of metric perturbations
+encountered during the non-relativistic phase of the C$\nu$B. This paper
+numerically compares the line-of-sight methods for computing C$\nu$B
+anisotropies with the Einstein-Boltzmann hierarchy solutions in linear theory
+for a range of neutrino masses. Angular power spectra are computed that are
+relevant to a future polarized tritium target run of the PTOLEMY experiment.
+Correlations between the C$\nu$B sky maps and galactic survey data are derived
+using line-of-sight techniques and discussed in the context of multi-messenger
+astrophysics.",2103.01274v3
+2021-03-05,Rubbing and Drawing: Generic Ways to Improve the Thermoelectric Power Factor of Organic Semiconductors?,"Highly oriented polymer films can show considerable anisotropy in the
+thermoelectric properties leading to power factors beyond those predicted by
+the widely obeyed power law linking the thermopower $S$ and the electrical
+conductivity $\sigma$ as $S\propto\sigma^{-1/4}$. This has led to encouraging
+practical results with respect to the electrical conductivity, notwithstanding
+that the conditions necessary to enhance $\sigma$ and $S$ simultaneously are
+less clear. Here, kinetic Monte Carlo simulations are used to study the impact
+of structural anisotropy on the thermoelectric properties of disordered organic
+semiconductors. We find that stretching is a suitable strategy to improve the
+conductivity along the direction of strain, while the effect on the power
+factor depends on the morphology the polymer crystallizes. In general,
+crystalline polymers show a simultaneous increase in $\sigma$ and $S$ which is
+not the case for amorphous polymers. Moreover, we show that the trends
+resulting from simulations based on variable-range hopping are in good
+agreement with experiments and can describe the different functional
+dependencies in the $S$ versus $\sigma$ behaviour of different directions.",2103.03814v1
+2021-03-10,New insights into star cluster evolution towards energy equipartition,"We present the results of a study aimed at exploring the evolution towards
+energy equipartition in star cluster models with different initial degrees of
+anisotropy in the velocity distribution. Our study reveals a number of novel
+aspects of the cluster dynamics and shows that the rate of evolution towards
+energy equipartition (1) depends on the initial degree of radial velocity
+anisotropy -- it is more rapid for more radially anisotropic systems; and (2)
+differs for the radial and the tangential components of the velocity
+dispersion. (3) The outermost regions of the initially isotropic system evolve
+towards a state of `inverted' energy equipartition in which high-mass stars
+have a larger velocity dispersion than low-mass stars -- this inversion
+originates from the mass-dependence of the tangential velocity dispersion
+whereas the radial velocity dispersion shows no anomaly. Our results add new
+fundamental elements to the theoretical framework needed to interpret the
+wealth of recent and upcoming observational studies of stellar kinematics in
+globular clusters, and shed further light on the link between the clusters'
+internal kinematics, their formation and evolutionary history.",2103.06272v1
+2021-03-11,"Giant rectification in segmented, strongly interacting, spin chains despite the presence of perturbations","In Phys. Rev. Lett. 120, 200603 (2018), a segmented XXZ spin chain with zero
+anisotropy in one half and a large anisotropy on the other half gave rise to a
+spin current rectification which is perfect in the thermodynamic limit. Here we
+extend the previous study to segmented chains with interacting integrable as
+well as non-integrable halves, considering even cases in which no ballistic
+transport can emerge in either half. We demonstrate that, also in this more
+general case, it is possible to obtain giant rectification when the two
+interacting half chains are sufficiently different. We also show that the
+mechanism causing this effect is the emergence of an energy gap in the
+excitation spectrum of the out-of-equilibrium insulating steady state in one of
+the two biases. Finally we demonstrate that in the thermodynamic limit there is
+no perfect rectification when each of the two half chains is interacting.",2103.06750v2
+2021-03-14,Transverse spin dynamics in the anisotropic Heisenberg model realized with ultracold atoms,"In Heisenberg models with exchange anisotropy, transverse spin components are
+not conserved and can decay not only by transport, but also by dephasing. Here
+we utilize ultracold atoms to simulate the dynamics of 1D Heisenberg spin
+chains, and observe fast, local spin decay controlled by the anisotropy.
+Additionally, we directly observe an effective magnetic field created by
+superexchange which causes an inhomogeneous decay mechanism due to variations
+of lattice depth between chains, as well as dephasing within each chain due to
+the twofold reduction of the effective magnetic field at the edges of the
+chains and due to fluctuations of the effective magnetic field in the presence
+of mobile holes. The latter is a new coupling mechanism between holes and
+magnons. All these dephasing mechanisms, corroborated by extensive numerical
+simulations, have not been observed before with ultracold atoms and illustrate
+basic properties of the underlying Hubbard model.",2103.07866v1
+2021-03-14,Relaxation of Thermal Capillary Waves for Nanoscale Liquid Films on Anisotropic-slip Substrates,"The relaxation dynamics of thermal capillary waves for nanoscale liquid films
+on anisotropic-slip substrates are investigated, using both molecular dynamics
+(MD) simulations and a Langevin model. The anisotropy of slip on substrates is
+achieved using a specific lattice plane of a face-centred cubic lattice. This
+surface's anisotropy breaks the simple scalar proportionality between slip
+velocity and wall shear stress and requires the introduction of a
+slip-coefficient tensor. The Langevin equation can describe both the growth of
+capillary wave spectra and the relaxation of capillary wave correlations, with
+the former providing a time scale for the surface to reach thermal equilibrium.
+Temporal correlations of interfacial Fourier modes, measured at thermal
+equilibrium in MD, demonstrate that (i) larger slip lengths lead to a faster
+decay in wave correlations, and (ii) unlike on isotropic-slip substrates, the
+time correlations of waves on anisotropic-slip substrates are wave-direction
+dependent. These findings emerge naturally from the proposed Langevin equation,
+which becomes wave-direction dependent, agrees well with MD results, and allows
+to produce experimentally-verifiable predictions.",2103.07965v2
+2021-03-15,"Magnetic phase diagram of $A_{2}$[FeCl$_{5}$(H$_{2}$O)] ($A$ = K, Rb, NH$_{4}$)","Erythrosiderites with the formula A2FeX5H2O, where A = Rb, K, and (NH4) and X
+= Cl and Br are intriguing systems that possess various magnetic and electric
+phases, as well as multiferroic phases in which magnetism and ferroelectricity
+are coupled. In this report, we study the magnetic phase diagram of
+erythrosiderites as a function of superexchange interactions. To this end, we
+perform classical Monte Carlo simulations on magnetic Hamiltonians that contain
+five different superexchange interactions with single-ion anisotropies. Our
+phase diagram contains all magnetic ground states that have been experimentally
+observed in these materials. We argue that the ground states can be explained
+by varying the ratio of J4/J2. For J4/J2 > 0.95 a cycloidal spins structure is
+stabilized as observed in (NH4)2FeCl5H2O and otherwise, a collinear spin
+structure is stabilized as observed in (K,Rb)2FeCl5H2O. We also show that the
+difference in the single-ion anisotropy along a- and c- axes is essential to
+stabilize the intermediate state observed in (NH)2FeCl5H2O.",2103.08500v2
+2021-03-16,A non-local fluid closure for modeling cyclotron resonance in collisionless magnetized plasmas,"A fluid description for collisionless magnetized plasmas that takes into
+account the effect of cyclotron resonance has been developed. Following the
+same approach as the Landau fluid closure, the heat flux components associated
+with transverse electromagnetic fluctuations are approximated by a linear
+combination of lower-order moments in wavenumber space. The closure
+successfully reproduces the linear cyclotron resonance for electromagnetic
+waves propagating parallel to the ambient magnetic field. In the presence of
+finite temperature anisotropy, the model gives approximately correct prediction
+for an instability destabilized via the cyclotron resonance. A nonlinear
+simulation demonstrates the wave growth consistent with the linear theory
+followed by the reduction of initial anisotropy, and finally, the saturation of
+the instability. The isotropization may be understood in terms of quasi-linear
+theory, which is developed within the framework of the fluid model but very
+similar to its fully kinetic counterpart. The result indicates that both linear
+and nonlinear collisionless plasma responses are approximately incorporated in
+the fluid model.",2103.08880v1
+2021-03-16,Stress-induced modification of gyration dynamics in stacked double-vortex structures studied by micromagnetic simulations,"In this paper, using micromagnetic simulations, we investigate the
+stress-induced frequency tunability of double-vortex nano-oscillators
+comprising magnetostrictive and non-magnetostrictive ferromagnetic layers
+separated vertically by a non-magnetic spacer. We show that the the relative
+orientations of the vortex core polarities $p_{1}$ and $p_{2}$ have a strong
+impact on the eigen-frequencies of the dynamic modes. When the two vortices
+with antiparallel polarities have different eigen-frequencies and the
+magnetostatic coupling between them is sufficiently strong, the stress-induced
+magnetoelastic anisotropy can lead to the single-frequency gyration mode of the
+two vortex cores. Additionally, for the case of parallel polarities, we
+demonstrate that for sufficiently strong magnetostatic coupling, the
+magnetoelastic anisotropy leads to the coupled vortex gyration in the
+stochastic regime and to the lateral separation of the vortex core
+trajectories. These findings offer a fine control over gyration frequencies and
+trajectories in vortex-based oscillators via adjustable elastic stress, which
+can be easily generated and tuned electrically, mechanically or optically.",2103.08940v2
+2021-03-16,"Experimental properties of continuously-forced, shear-driven, stratified turbulence. Part 2. Energetics, anisotropy, parameterisation","In this Part 2 we study further experimental properties of two-layer exchange
+flows in a stratified inclined duct (SID), which are turbulent,
+strongly-stratified, shear-driven, and continuously-forced. We analyse the same
+state-of-the-art data sets using the same core shear layer methodology as in
+Part 1, but we focus here on turbulent energetics and mixing statistics. The
+detailed analysis of kinetic and scalar energy budgets reveals the specificity
+and scalings of SID turbulence, while energy spectra provide insight into the
+current strengths and limitations of our experimental data. The anisotropy of
+the flow at different scales characterises the turbulent kinetic energy
+production and dissipation mechanisms of Holmboe waves and turbulence. We then
+assess standard mixing parameterisations models relying on uniform eddy
+diffusivities, mixing lengths, flux parameters, buoyancy Reynolds numbers or
+turbulent Froude numbers, and we compare representative values with the
+stratified mixing literature. The dependence of these measures of mixing on
+controllable flow parameters is also elucidated, providing asymptotic estimates
+that may be extrapolated to more strongly turbulent flows, quantified by the
+product of the tilt angle of the duct and the Reynolds number. These insights
+may serve as benchmark for the future generation of experimental data with
+superior spatio-temporal resolution required to probe increasingly vigorous
+turbulence.",2103.09193v1
+2021-03-23,A Scenario for a Singularity-free Generic Cosmological Solution,"We develop a scenario for the emergence of a non-singular generic
+cosmological solution based on the a WKB characterization of one of the two
+anisotropy degrees of freedom. We investigate the dynamics of the so-called
+inhomogeneous mixmaster in the ""corner"" configuration and inferring that one of
+the two anisotropic variables becomes small enough to explore the uncertainty
+principle. Then, we apply a standard WKB approximation to the dynamics of the
+Universe which has macroscopic volume, one macroscopic anisotropy and one
+microscopic quantum degree of freedom. Our study demonstrates the possibility
+that the Universe acquires a non-singular classical behavior, retaining the
+quantum degree of freedom as a small oscillating ripple on a stationary
+Universe. The role of the so-called ""fragmentation process"" is also taken into
+account in outlining the generality of such a behavior in independent local
+space regions.",2103.12473v2
+2021-03-23,Anisotropic relativistic fluid spheres with a linear equation of state,"In this work, we present a class of relativistic and well-behaved solution to
+Einstein's field equations for anisotropic matter distribution. We perform our
+analysis by using the Buchdahl ansatz for the metric function grr. Three
+different classes of new exact solution are found for anisotropy factor(delta).
+We have analyzed our model with various physical aspects such as pressure
+(radial as well as transverse), energy density, anisotropy factor, mass,
+compactness parameter, adiabatic index(gamma) and surface redshift. A graphical
+analysis of energy conditions, TOV equation and causality condition indicates
+the model are well behaved. The physical acceptability of the model has
+verified by considering compact objects with similar mass and radii, such as 4U
+1820-30,Vela X-1, PSR J1614-2230, LMC X-4, SMC X-1, 4U 1538-52, Her X-1, Cyg
+X-2, PSR B1913+16 and PSR J1903+327.",2103.12583v2
+2021-03-24,Effective strain manipulation of the antiferromagnetic state of polycrystalline NiO,"As a candidate material for applications such as magnetic memory,
+polycrystalline antiferromagnets offer the same robustness to external magnetic
+fields, THz spin dynamics, and lack of stray field as their single crystalline
+counterparts, but without the limitation of epitaxial growth and lattice
+matched substrates. Here, we first report the detection of the average Neel
+vector orientiation in polycrystalline NiO via spin Hall magnetoresistance
+(SMR). Secondly, by applying strain through a piezo-electric substrate, we
+reduce the critical magnetic field required to reach a saturation of the SMR
+signal, indicating a change of the anisotropy. Our results are consistent with
+polycrystalline NiO exhibiting a positive sign of the in-plane
+magnetostriction. This method of anisotropy-tuning offers an energy efficient,
+on-chip alternative to manipulate a polycrystalline antiferromagnets magnetic
+state.",2103.13105v1
+2021-03-25,Constraints on the initial state of PbPb collisions via measurements of Z boson yields and azimuthal anisotropy at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV,"The CMS experiment at the LHC has measured the differential cross sections of
+Z bosons decaying to pairs of leptons, as functions of transverse momentum and
+rapidity, in lead-lead collisions at a nucleon-nucleon center-of-mass energy of
+5.02 TeV. The measured Z boson elliptic azimuthal anisotropy coefficient is
+compatible with zero, showing that Z bosons do not experience significant
+final-state interactions in the medium produced in the collision. Yields of Z
+bosons are compared to Glauber model predictions and are found to deviate from
+these expectations in peripheral collisions, indicating the presence of initial
+collision geometry and centrality selection effects. The precision of the
+measurement allows, for the first time, for a data-driven determination of the
+nucleon-nucleon integrated luminosity as a function of lead-lead centrality,
+thereby eliminating the need for its estimation based on a Glauber model.",2103.14089v2
+2021-03-26,Conjectures on Hidden Onsager Algebra Symmetries in Interacting Quantum Lattice Models,"We conjecture the existence of hidden Onsager algebra symmetries in two
+interacting quantum integrable lattice models, i.e. spin-1/2 XXZ model and
+spin-1 Zamolodchikov-Fateev model at arbitrary root of unity values of the
+anisotropy. The conjectures relate the Onsager generators to the conserved
+charges obtained from semi-cyclic transfer matrices. The conjectures are
+motivated by two examples which are spin-1/2 XX model and spin-1 U(1)-invariant
+clock model. A novel construction of the semi-cyclic transfer matrices of
+spin-1 Zamolodchikov-Fateev model at arbitrary root of unity value of the
+anisotropy is carried out via transfer matrix fusion procedure.",2103.14569v5
+2021-04-10,Spin-Hall nanooscillator based on an antiferromagnetic domain wall,"We propose here a high-frequency spin-Hall nano-oscillator based on a simple
+magnetic texture, such as a domain wall, located in an antiferromagnet with
+easy-axis anisotropy type. We show that the spin current, polarized along the
+anisotropy axis, excites a conical precession of the N\'eel vector in such a
+domain wall, which allows obtaining a robust ac output signal, -- contrary to
+the planar precession in an uniform uniaxial antiferromagnet, where ac output
+is hard to achieve. The frequency of the auto-oscillations is easily tunable by
+the applied current up to the THz range, and the threshold current vanishes for
+pure uniaxial antiferromagnet. By micro-magnetic simulations, we demonstrate
+that the pinning of the domain wall is crucial for the oscillator design, which
+can be achieved in nano-constriction layout of the free layer.",2104.04780v3
+2021-04-13,Considerations towards quantitative X-ray and neutron tensor tomography: on the validity of linear approximations of dark-field anisotropy,"The validity of two approximative linear tensor models to be used for grating
+based X-ray or neutron dark-field tensor tomography is investigated in a
+simulation study. While the dark-field contrast originating from anisotropic
+microscopic mass distributions has, in a previous study, been confirmed to be
+in general a non-linear function of two orientations (optical axis and axis of
+interferometer sensitivity), linear approximations with a reduced parameter
+space (considering only one of the orientation dependencies) are highly
+preferable with respect to tomographic volume reconstruction from projections.
+By regarding isolated volume elements and systematically exploring the full
+range of possible anisotropies, direct correspondences are drawn between the
+respective tensors characterizing the complete model used for signal
+synthesization and the reduced linear models used for reconstruction. The
+tensors' dominant orientations are found to agree to a typical accuracy of
+1{\deg}, with their eigenspectra exhibiting fuzzy, yet almost linear relations
+among each other. Although modeling only either of two orientation dependencies
+for the purpose of tensor reconstruction, the data acquisition scheme must
+nevertheless adequately address both dependencies.",2104.06235v1
+2021-04-13,Tryptophan-containing proteins as label-free nanothermometers,"There remains a need for techniques to monitor thermal processes at high
+spatiotemporal resolution, with myriad potential applications in chemistry,
+biology, and engineering. Measurement of temperature from nanoscale molecular
+phenomena are particularly promising due to their general compatibility with
+biological systems. Among these phenomena, fluorescence polarization anisotropy
+is particularly attractive due to its high sensitivity to thermal and
+photophysical information, and its general utility with a wide spectrum of
+fluorophores. In this work, we propose that the measurement of the intrinsic
+fluorescence polarization anisotropy of tryptophan can be used to measure
+label-free temperature at the nanoscale in a variety of tryptophan-containing
+proteins. We present a theoretical model of the temperature sensitivity of
+fluorescence polarization in free tryptophan and tryptophan-containing
+proteins, empirically explore these properties, and discuss the potential
+development of proteins as thermal memory sensors.",2104.06409v1
+2021-04-14,Anisotropic heating and magnetic field generation due to Raman scattering in laser-plasma interactions,"We identify a mechanism for magnetic field generation in the interaction of
+intense electromagnetic waves and underdense plasmas. We show that Raman
+scattered plasma waves trap and heat the electrons preferentially in their
+propagation direction, resulting in a temperature anisotropy. In the trail of
+the laser pulse, we observe magnetic field growth which matches the Weibel
+mechanism due to the temperature anisotropy. We discuss the role of the initial
+electron temperature in our results. The predictions are confirmed with
+multi-dimensional particle-in-cell simulations. We show how this configuration
+is an experimental platform to study the long-time evolution of the Weibel
+instability.",2104.06734v1
+2021-04-15,Origins of anisotropic transport in electrically-switchable antiferromagnet $\mathrm{Fe_1/3NbS_2}$,"Recent experiments on the antiferromagnetic intercalated transition metal
+dichalcogenide $\mathrm{Fe_{1/3}NbS_2}$ have demonstrated reversible
+resistivity switching by application of orthogonal current pulses below its
+magnetic ordering temperature, making $\mathrm{Fe_{1/3}NbS_2}$ promising for
+spintronics applications. Here, we perform density functional theory
+calculations with Hubbard U corrections of the magnetic order, electronic
+structure, and transport properties of crystalline $\mathrm{Fe_{1/3}NbS_2}$,
+clarifying the origin of the different resistance states. The two
+experimentally proposed antiferromagnetic ground states, corresponding to
+in-plane stripe and zigzag ordering, are computed to be nearly degenerate.
+In-plane cross sections of the calculated Fermi surfaces are anisotropic for
+both magnetic orderings, with the degree of anisotropy sensitive to the Hubbard
+U value. The in-plane resistance, computed within the Kubo linear response
+formalism using a constant relaxation time approximation, is also anisotropic,
+supporting a hypothesis that the current-induced resistance changes are due to
+a repopulating of AFM domains. Our calculations indicate that the transport
+anisotropy of $\mathrm{Fe_{1/3}NbS_2}$ in the zigzag phase is reduced relative
+to stripe, consistent with the relative magnitudes of resistivity changes in
+experiment. Finally, our calculations reveal the likely directionality of the
+current-domain response, specifically, which domains are energetically
+stabilized for a given current direction.",2104.07591v1
+2021-04-18,Acceptability Conditions and Relativistic Anisotropic Generalized Polytropes,"This paper explored the physical acceptability conditions for anisotropic
+matter configurations in General Relativity. The study considered a generalized
+polytropic equation of state $P=\kappa {\rho}^{\gamma}+\alpha \rho -\beta$ for
+a heuristic anisotropy. We integrated the corresponding Lane-Emden equation for
+several hundred models and found the parameter-space portion ensuring the
+configurations' acceptability. Polytrope based on the total energy density are
+more stable than those with baryonic density, and small positive local
+anisotropies produce acceptable models. We also found that polytropic
+configurations where tangential pressures are greater than radial ones are also
+more acceptable. Finally, convective disturbances do not generate cracking
+instabilities. Several models emerging from our simulations could represent
+candidate of astrophysical compact objects.",2104.08923v4
+2021-04-22,Impact of Fe$_{80}$B$_{20}$ insertion on the properties of dual-MgO perpendicular magnetic tunnel junctions,"We explore the impact of Fe80B20 inserted at both
+Co$_{20}$Fe$_{80}$B$_{20}$/MgO interfaces of dual-MgO free layers (FLs) in
+bottom-pinned magnetic tunnel junctions (MTJs). MTJ stacks are annealed for 30
+min at 350 $^\circ$C and 400 $^\circ$C in a vacuum after film deposition.
+Current-in-plane tunneling measurements are carried out to characterize
+magnetotransport properties of the MTJs. Conventional magnetometry measurements
+and ferromagnetic resonance are conducted to estimate the saturation
+magnetization, the effective perpendicular anisotropy field and the Gilbert
+damping of dual-MgO FLs as a function of the Fe$_{80}$B$_{20}$ thickness and
+annealing temperatures. With ultrathin Fe$_{80}$B$_{20}$ (0.2 - 0.4 nm)
+inserted, perpendicular magnetic anisotropy (PMA) of FLs increases with similar
+tunnel magneto-resistance (TMR) and low damping values. As Fe$_{80}$B$_{20}$
+layer thickness further increases (0.6 - 1.2 nm), both TMR and PMA degrade, and
+damping increases dramatically. This study demonstrates a novel approach to
+tune properties of MTJ stacks with dual-MgO FLs up to 400 $^\circ$C annealing,
+which enables MTJ stacks for various applications.",2104.10918v1
+2021-04-26,A Theoretical Framework for the Electrochemical Characterization of Anisotropic Micro-Emulsions,"Micro emulsions (MEs) offer an exceptionally broad spectrum of applications
+covering sensing, electrosynthesis, supercapacitors and redox-flow batteries.
+Herein, we develop the theory for a sophisticated electrochemical
+characterizion of MEs with a spatially and time-invariant anisotropy in the
+diffusion domain by means of cyclic voltammerty (CV). By introducing spatially
+dependent diffusion coefficients into Ficks' first law, we derive a modified
+diffusion equation to simulate any inherent anisotropy of the ME under
+investigation. Moreover, by formulating an extended second-order homogeneous
+six-member square scheme for a kinetically controlled two-step two-electron
+reaction we capture the intricate entanglement of chemical and electrochemical
+equilibria. Our theoretical concept is finally validated by experimental CV
+data for the ME based two-step redox reaction of methyl-viologen which paves
+the way for a quantitative electrochemical characterization MEs.",2104.12342v1
+2021-04-28,Method for critical current angular dependencies analysis of superconducting tapes,"Various applications of superconducting materials require accounting of
+anisotropy of the current-carrying capacity relative to magnetic field
+direction - Ic({\theta}). However, today there is no sufficiently comprehensive
+model that takes into account the anisotropy, therefore the angular dependences
+are usually not analysed, but only described using various mathematical
+formulas. As a result, the fitting parameters have no physical meaning and it
+is difficult to correlate the picture with the features of the microstructure.
+In this paper, we propose a method for analysing the critical current angular
+dependences based on the anisotropic pinning model. The applicability of this
+model for conventional superconducting Nb-Ti tapes with one peak in the Ic
+({\theta}) dependence is shown. The possibility of extending this model to
+analyse the angular dependences of HTS materials is discussed.",2104.13596v1
+2021-04-28,Anisotropic Landau-Lifshitz Model in Discrete Space-Time,"We construct an integrable lattice model of classical interacting spins in
+discrete space-time, representing a discrete-time analogue of the lattice
+Landau-Lifshitz ferromagnet with uniaxial anisotropy. As an application we use
+this explicit discrete symplectic integration scheme to compute the spin Drude
+weight and diffusion constant as functions of anisotropy and chemical
+potential. We demonstrate qualitatively different behavior in the easy-axis and
+the easy-plane regimes in the non-magnetized sector. Upon approaching the
+isotropic point we also find an algebraic divergence of the diffusion constant,
+signaling a crossover to spin superdiffusion.",2104.13863v3
+2021-04-28,Thermal diffusivity and its lower bound in orthorhombic SnSe,"The orthorhombic monochalcogenide SnSe has attracted much attention in recent
+years as a promising high-temperature thermoelectric material. We present a
+study of its thermal conductivity and specific heat of SnSe between 2~K and
+300~K and quantify its anisotropic thermal diffusivity, $D$. For both
+crystallographic orientations, thermal diffusivity remains above the recently
+identified Planckian limit ($D > v_s^2 \tau_P$, where $v_s$ is the sound
+velocity and $\tau_P= \hbar/k_BT$) and its anisotropy in $D$ is set by the
+anisotropy of $v_s$. Comparison with cubic members of the IV-VI family leads to
+a consistent picture, where the diffusivity in all members of the family is set
+by the product of v$_s$, $\tau_P$ and the 'melting' velocity derived from the
+melting temperature.",2104.13994v2
+2021-04-29,Nano-patterning of surfaces by ion sputtering: Numerical study of the anisotropic damped Kuramoto-Sivashinsky equation,"Nonlinear models for pattern evolution by ion beam sputtering on a material
+surface present an ongoing opportunity for new numerical simulations. A
+numerical analysis of the evolution of preexisting patterns is proposed to
+investigate surface dynamics, based on a 2D anisotropic damped
+Kuramoto-Sivashinsky equation, with periodic boundary conditions. A
+finite-difference semi-implicit time splitting scheme is employed on the
+discretization of the governing equation. Simulations were conducted with
+realistic coefficients related to physical parameters (anisotropies, beam
+orientation, diffusion). The stability of the numerical scheme is analyzed with
+time step and grid spacing tests for the pattern evolution, and the Method of
+Manufactured Solutions has been used to verify the proposed scheme. Ripples and
+hexagonal patterns were obtained from a monomodal initial condition for certain
+values of the damping coefficient, while spatiotemporal chaos appeared for
+lower values. The anisotropy effects on pattern formation were studied, varying
+the angle of incidence of the ion beam with respect to the irradiated surface.
+Analytical discussions are based on linear and weakly nonlinear analysis.",2104.14104v1
+2021-04-29,Directional Dependence of the Electronic and Transport Properties of 2D Monolayer Orthorhombic Diboron Dinitride (o-B2N2): DFT coupled with NEGF Study,"Tuning two dimensional nanomaterial's structural and electronic properties
+has facilitated the new research paradigm in electronic device applications. In
+this work, the first principles density functional theory based methods are
+used to investigate the structural, electronic, and transport properties of an
+orthorhombic diboron dinitride based polymorph. Interestingly, it depicts a low
+band gap semiconducting nature with a robust anisotropic behaviour compared to
+the hexagonal boron nitride, which is an insulator and isotropic. We can also
+tune the structural and electronic properties of the semiconducting B2N2 based
+structure through an external inplane mechanical strain. Further, by employing
+the Landauer Buttiker approach, the electronic transmission function, and
+electric current calculations reveal that the diboron dinitride based polymorph
+shows a robust direction dependent anisotropy of the quantum transport
+properties. We have demonstrated the direction dependence of the electric
+current in two perpendicular directions, where we have observed an electric
+current ratio of around 61.75 at 0.8 V. All these findings, such as directional
+dependence anisotropy in transmission function, current voltage
+characteristics, and bandgap tunning, suggest that the applicability of such
+B2N2 based monolayer can be promising for futuristic electronic device
+applications.",2104.14369v1
+2021-04-29,Direct photons emission rate and electric conductivity in twice anisotropic QGP holographic model with first-order phase transition,"The electric conductivity and direct photons emission rate are considered in
+the holographic theory with two types of anisotropy. The electric conductivity
+is derived in two different ways, and their equivalence for the twice
+anisotropic theory is shown. Numerical calculations of the electric
+conductivity were done for Einstein-dilaton-three-Maxwell holographic model
+[29]. The dependence of the conductivity on the temperature, the chemical
+potential, the external magnetic field, and the spatial anisotropy of the
+heavy-ions collision (HIC) is studied. The electric conductivity jumps near the
+first-order phase transition are observed. This effect is similar to the jumps
+of holographic entanglement that were studied previously.",2104.14582v3
+2021-04-30,Control of stripe domain wall magnetization in perpendicular anisotropy multilayers,"We report on the controlled switching of domain wall (DW) magnetization in
+aligned stripe domain structures, stabilized in [Co (0.44 nm)/Pt (0.7 nm)]$_X$
+($X = 48$, 100, 150) multilayers with perpendicular magnetic anisotropy. The
+switching process, induced by an external magnetic field, is monitored by
+measuring the evolution of the in-plane magnetization. % We show that the
+remanent in-plane magnetization originates from the polarization of the
+Bloch-type DWs. With micromagnetic simulations, we reveal that the reversal of
+the DW polarization is the result of the emergence and collapse of horizontal
+Bloch lines within the DWs at particular strengths of the external magnetic
+field, applied opposite to the DW polarization. Our findings are relevant for
+DW-based magnonics and bubble skyrmion applications in magnetic multilayers.",2104.14934v1
+2021-05-09,Sensing Strain-induced Symmetry Breaking by Reflectance Anisotropy Spectroscopy,"Intentional breaking of the lattice symmetry in solids is a key concept to
+alter the properties of materials by modifying their electronic band structure.
+However, the correlation of strain-induced effects and breaking of the lattice
+symmetry is often indirect, resorting to vibrational spectroscopic techniques
+such as Raman scattering. Here, we demonstrate that reflectance anisotropy
+spectroscopy (RAS), which directly depends on the complex dielectric function,
+enables the direct observation of electronic band structure modulation.
+Studying the strain-induced symmetry breaking in copper, we show how uniaxial
+strain lifts the degeneracy of states in the proximity of the both L and X
+symmetry points, thus altering the matrix element for interband optical
+transitions, directly observable in RAS. We corroborate our experimental
+results by analysing the strain-induced changes in the electronic structure
+based on ab-initio density functional theory calculations. The versatility to
+study breaking of the lattice symmetry by simple reflectance measurements opens
+up the possibility to gain a direct insight on the band-structure of other
+strain-engineered materials, such as graphene and two-dimensional (2D)
+transition metal dichalcogenides (TMDCs).",2105.03846v3
+2021-05-10,Robust magnetic anisotropy of a monolayer of hexacoordinate Fe( ii ) complexes assembled on Cu(111),"The tris pyrazolyl borate ligand imposes a rigid scaffold around Fe( ii )
+ensuring a robust magnetic anisotropy when the molecules assembled as
+monolayers suffer from the dissymmetric environment of the substrate/vacuum
+interface.",2105.04199v1
+2021-05-11,Strength and energy consumption of inherently anisotropic rocks at failure,"Using a discrete-element approach and a bonding interaction law, we model and
+test crushable inherently anisotropic structures reminiscent of the layering
+found in sedimentary and metamorphic rocks. By systematically modifying the
+level of inherent anisotropy, we characterize the evolution of the failure
+strength of circular rock samples discretized using a modified Voronoi
+tesselation under diametral point loading at different orientations relative to
+the sample's layers. We characterize the failure strength, which can
+dramatically increase as the loading becomes orthogonal to the rock layers. We
+also describe the evolution of the macroscopic failure modes as a function of
+the loading orientation and the energy consumption at fissuring. Our simulation
+strategy let us conclude that the length of bonds between Voronoi cells
+controls the energy being consumed in fissuring the rock sample, although
+failure modes and strength are considerably changing. We end up this work
+showing that the microstructure is largely afected by the level of inherent
+anisotropy and loading orientation.",2105.05288v1
+2021-05-14,Yu-Shiba-Rusinov states in real metals,"Theoretical descriptions of Yu-Shiba-Rusinov (YSR) states induced by magnetic
+impurities inside the gap of a superconductor typically rely on a classical
+spin model or are restricted to spin-1/2 quantum spins. These models fail to
+account for important aspects of YSR states induced by transition-metal
+impurities, including the effects of higher quantum spins coupled to several
+conduction-electron channels, crystal or ligand-field effects, and magnetic
+anisotropy. We introduce and explore a zero-bandwidth model, which incorporates
+these aspects, is readily solved numerically, and analytically tractable in
+several limiting cases. The principal simplification of the model is to neglect
+Kondo renormalizations of the exchange couplings between impurity spin and
+conduction electrons. Nevertheless, we find excellent correspondence in those
+cases, in which we can compare our results to existing
+numerical-renormalization-group calculations. We apply the model to obtain and
+understand phase diagrams as a function of pairing strength and magnetic
+anisotropy as well as subgap excitation spectra. The single-channel case is
+most relevant for transition-metal impurities embedded into metallic
+coordination complexes on superconducting substrates, while the multi-channel
+case models transition-metal adatoms.",2105.06651v1
+2021-05-16,Anatomy of inertial magnons in ferromagnets,"We analyze dispersion relations of magnons in ferromagnetic nanostructures
+with uniaxial anisotropy taking into account inertial terms, i.e. magnetic
+nutation. Inertial effects are parametrized by damping-independent parameter
+$\beta$, which allows for an unambiguous discrimination of inertial effects
+from Gilbert damping parameter $\alpha$. The analysis of magnon dispersion
+relation shows its two branches are modified by the inertial effect, albeit in
+different ways. The upper nutation branch starts at $\omega=1/ \beta$, the
+lower branch coincides with FMR in the long-wavelength limit and deviates from
+the zero-inertia parabolic dependence $\simeq\omega_{FMR}+Dk^2$ of the exchange
+magnon. Taking a realistic experimental geometry of magnetic thin films,
+nanowires and nanodiscs, magnon eigenfrequencies, eigenvectors and $Q$-factors
+are found to depend on the shape anisotropy. The possibility of phase-matched
+magneto-elastic excitation of nutation magnons is discussed and the condition
+was found to depend on $\beta$, exchange stiffness $D$ and the acoustic
+velocity.",2105.07376v1
+2021-05-17,Contact force measurements and local anisotropy in ellipses and disks,"Experimental measurements of contact forces are limited to spheres and disks
+in three and two dimensions, making the evaluation of the shape effect and
+universality of force distributions and the comparison between experiments and
+theories extremely difficult. Here we present precise measurements of vector
+contact forces in photoelastic ellipses and disks subject to isotropic
+compression and pure shear. We find the local, instead of the global, stress
+ratio, control the width of the force distributions for forces larger than the
+mean, regardless of the particle shape and preparation protocols. By taking
+advantage of the anisotropic particle shape, we can determine the anisotropic
+growth of contacts in ellipses subject to isotropic compression, revealing the
+role of non-affine particle motions in homogenizing force distributions. Our
+results uncover the role of local anisotropy in the statistical framework of
+granular materials and open a new regime of exploring the role of particle
+shape on the mechanical and dynamical properties of granular materials in
+depth.",2105.07607v2
+2021-05-19,"Rashba-type Dzyaloshinskii-Moriya interaction, perpendicular magnetic anisotropy and skyrmion states at 2D materials/Co interfaces","We report a significant Dzyaloshinskii-Moriya interaction (DMI) and
+perpendicular magnetic anisotropy (PMA) at interfaces comprising hexagonal
+boron nitride (h-BN) and Co. By comparing the behavior of these phenomena at
+graphene/Co and h-BN/Co interfaces, it is found that the DMI in latter
+increases as a function of Co thickness and beyond three monolayers stabilizes
+with one order of magnitude larger values compared to those at graphene/Co,
+where the DMI shows opposite decreasing behavior. At the same time, the PMA for
+both systems shows similar trends with larger values for graphene/Co and no
+significant variations for all thickness ranges of Co. Furthermore, using
+micromagnetic simulations we demonstrate that such significant DMI and PMA
+values remaining stable over large range of Co thickness give rise to formation
+of skyrmions with small applied external fields in the range of 200-250 mT up
+to 100 K temperatures. These findings open up further possibilities towards
+integrating two-dimensional (2D) materials in spin-orbitronics devices.",2105.09015v1
+2021-05-19,Structural and Morphological Effect of Ti underlayer on Pt/Co/Pt Magnetic Ultra-Thin Film,"Pt(x{\AA})/Co(5{\AA})/Pt(10{\AA}) trilayer films were deposited on naturally
+oxidized Si(111) substrate to investigate Ti underlayer effect on PMA. A small
+amount of Ti underlayer promoted the magnetic anisotropy to a perpendicular
+direction for x=8{\AA} and 10{\AA}. Both GI XRD and STM results showed that the
+Ti underlayer manipulated the growth of trilayer film. The Pt particles
+preferably grow the neighborhood of the Ti cluster, giving rise to a relatively
+smooth layer with a fiber texture fcc (111) structure. By contrast, the absence
+of Ti underlayer leads to clustered, relatively rough, and randomly oriented
+nano-crystalline growth. Differences in the growth mode, especially roughness,
+also appeared as intensity loss in XPS spectra due to shadowing effects. Our
+results indicate that a traceable amount of underlayer can change the magnetic
+anisotropy of the film by manipulating film growth.",2105.09355v1
+2021-04-25,Implementation of two-field inflation for cosmic linear anisotropy solving system,"We outline the modifications in the numerical Boltzmann code Cosmic Linear
+Anisotropy Solving System (CLASS) in order to include extra inflationary
+fields. The functioning of the code is first described, how and where
+modifications are meant to be done are later explained. In the present study,
+we focus on the modifications needed for the implementation of a two-field
+inflationary model, with canonical kinetic terms and a polynomial potential
+with no cross terms, presenting preliminary results for the effect of the
+second field on the spectra. The adaptability of the code is exploited, making
+use of the classes and structures of C and the generic Runge-Kutta integration
+tool provided by the program.",2105.09747v1
+2021-05-22,Spin Seebeck effect of correlated magnetic molecules,"In this paper we investigate the spin-resolved thermoelectric properties of
+strongly correlated molecular junctions in the linear response regime. The
+magnetic molecule is modeled by a single orbital level to which the molecular
+core spin is attached by an exchange interaction. Using the numerical
+renormalization group method we analyze the behavior of the (spin) Seebeck
+effect, heat conductance and figure of merit for different model parameters of
+the molecule. We show that the thermopower strongly depends on the strength and
+type of the exchange interaction as well as the molecule's magnetic anisotropy.
+When the molecule is coupled to ferromagnetic leads, the thermoelectric
+properties reveal an interplay between the spin-resolved tunneling processes
+and intrinsic magnetic properties of the molecule. Moreover, in the case of
+finite spin accumulation in the leads, the system exhibits the spin Seebeck
+effect. We demonstrate that a considerable spin Seebeck effect can develop when
+the molecule exhibits an easy-plane magnetic anisotropy, while the sign of the
+spin thermopower depends on the type and magnitude of the molecule's exchange
+interaction.",2105.10713v1
+2021-05-26,Antiferromagnetic magnons and local anisotropy: dynamical mean-field study,"We present a dynamical mean-field study of antiferromagnetic magnons in one-,
+two- and three-orbital Hubbard model of square and bcc cubic lattice at
+intermediate coupling strength. Weinvestigate the effect of anisotropy
+introduced by an external magnetic field or single-ion anisotropy.For the
+latter we tune continuously between the easy-axis and easy-plane models. We
+also analyzea model with spin-orbit coupling in cubic site-symmetry setting.
+The ordered states as well as themagnetic excitations are sensitive to even a
+small breaking ofSU(2)symmetry of the model andfollow the expectations of
+spin-wave theory as well as general symmetry considerations.",2105.12468v2
+2021-05-27,Numerical method for the equilibrium configurations of a Maier-Saupe bulk potential in a Q-tensor model of an anisotropic nematic liquid crystal,"We present a numerical method, based on a tensor order parameter description
+of a nematic phase, that allows fully anisotropic elasticity. Our method thus
+extends the Landau-de Gennes $\mathbf{Q}$-tensor theory to anisotropic phases.
+A microscopic model of the nematogen is introduced (the Maier-Saupe potential
+in the case discussed in this paper), combined with a constraint on eigenvalue
+bounds of $\mathbf{Q}$. This ensures a physically valid order parameter
+$\mathbf{Q}$ (i.e., the eigenvalue bounds are maintained), while allowing for
+more general gradient energy densities that can include cubic nonlinearities,
+and therefore elastic anisotropy. We demonstrate the method in two specific two
+dimensional examples in which the Landau-de Gennes model including elastic
+anisotropy is known to fail, as well as in three dimensions for the cases of a
+hedgehog point defect, a disclination line, and a disclination ring. The
+details of the numerical implementation are also discussed.",2105.13317v1
+2021-05-28,Strange star with Krori-Barua potential in presence of anisotropy,"In present paper a well-behaved new model of anisotropic compact star in
+(3+1)-dimensional spacetime has been investigated in the background of
+Einstein's general theory of relativity. The model has been developed by
+choosing $g_rr$ component as Krori-Barua (KB) ansatz [Krori and Barua in J.
+Phys. A, Math. Gen. 8:508, 1975]. The field equations have been solved by a
+proper choice of the anisotropy factor which is physically reasonable and well
+behaved inside the stellar interior. Interior spacetime has been matched
+smoothly to the exterior Schwarzschild vacuum solution and it has also been
+depicted graphically. Model is free from all types of singularities and is in
+static equilibrium under different forces acting on the system. The stability
+of the model has been tested with the help of various conditions available in
+literature. The solution is compatible with observed masses and radii of a few
+compact stars.",2105.15143v1
+2021-06-01,Topological spin textures in chiral magnets on the honeycomb lattice with magnetic fields,"Topological spin textures, like skyrmions, have significant potential for
+spintronics applications. The main purpose of this work is to study further the
+topological spin textures on the discrete lattice with magnetic fields. In this
+work, we study a classical rotated Heisenberg model with Dzyaloshinskii-Moriya
+interaction, bond-dependent anisotropy and easy-axis anisotropy on the
+honeycomb lattice via Monte Carlo simulations. We mainly focus on phase
+diagrams with magnetic fields, especially on the non-trivial phases only
+existing with fields. The results demonstrate the emergence of field-induced
+incommensurate skyrmion superlattice including mixed skyrmion-bimeron states,
+ferromagnetic star, vortex and z-vortex superlattice. We systematically analyze
+structures of these topological spin textures through spin configurations,
+structure factors, topological charge and vector chirality. We hope that our
+results could be useful for the identification of topological phases
+experimentally.",2106.00207v3
+2021-06-01,CMB anisotropies and linear matter power spectrum in models with non-thermal neutrinos and primordial magnetic fields,"Angular power spectra of temperature anisotropies and polarization of the
+cosmic microwave background (CMB) as well as the linear matter power spectra
+are calculated for models with three light neutrinos with non-thermal
+phase-space distributions in the presence of a primordial stochastic magnetic
+field. The non-thermal phase-space distribution function is assumed to be the
+sum of a Fermi-Dirac and a gaussian distribution. It is found that the known
+effective description of the non-thermal model in terms of a twin thermal model
+with extra relativistic degrees of freedom can also be extended to models
+including a stochastic magnetic field. Numerical solutions are obtained for a
+range of magnetic field parameters.",2106.00648v2
+2021-06-04,Cross-correlating Astrophysical and Cosmological Gravitational Wave Backgrounds with the Cosmic Microwave Background,"General Relativity provides us with an extremely powerful tool to extract at
+the same time astrophysical and cosmological information from the Stochastic
+Gravitational Wave Backgrounds (SGWBs): the cross-correlation with other
+cosmological tracers, since their anisotropies share a common origin and the
+same perturbed geodesics. In this letter we explore the cross-correlation of
+the cosmological and astrophysical SGWBs with Cosmic Microwave Background (CMB)
+anisotropies, showing that future GW detectors, such as LISA or BBO, have the
+ability to measure such cross-correlation signals. We also present, as a new
+tool in this context, constrained realization maps of the SGWBs extracted from
+the high-resolution CMB {\it Planck} maps. This technique allows, in the
+low-noise regime, to faithfully reconstruct the expected SGWB map by starting
+from CMB measurements.",2106.02591v2
+2021-06-05,Heat rectification by two qubits coupled with Dzyaloshinskii-Moriya interaction,"We investigate heat rectification in a two-qubit system coupled via the
+Dzyaloshinskii-Moriya (DM) interaction. We derive analytical expressions for
+heat currents and thermal rectification and provide possible physical
+mechanisms behind the observed results. We show that the anisotropy of DM
+interaction in itself is insufficient for heat rectification, and some other
+form of asymmetry is needed. We employ off-resonant qubits as the source of
+this asymmetry. We find the regime of parameters for higher rectification
+factors by examining the analytical expressions of rectification obtained from
+a global master equation solution. In addition, it is shown that the direction
+and quality of rectification can be controlled via various system parameters.
+Furthermore, we compare the influence of different orientations of the DM field
+anisotropy on the performance of heat rectification. Finally, we investigate
+the possible interplay between quantum correlations and the performance of the
+quantum thermal rectifier. We find that asymmetry in the coherences is a
+fundamental resource for the performance of the quantum thermal rectifier.",2106.02891v3
+2021-06-07,Crystal field effects in the zig-zag chain compound SrTm$_2$O$_4$,"The single ion properties of the zig-zag chain compound SrTm$_2$O$_4$ have
+been investigated using heat capacity, magnetic susceptibility, magnetization,
+inelastic neutron scattering, and polarized muon spectroscopy. Two crystal
+field models are employed to estimate the single ion properties; a Density
+Function Theory based model and an effective charge model based on the
+Hutchings point charge model. The latter describes our experimental results
+well. This model estimates an easy-axis anisotropy for one of the Tm$^{3+}$
+sites and an easy-plane anisotropy for the second site. It also predicts a
+mixed ground state with dominating $J = 0$ characteristics for both sites.
+Additionally, muon spin rotation/relaxation ($\mu^+$SR) spectra reveal
+oscillations, typically a sign of long-range magnetic order. However, the
+temperature dependence of the precession frequency and the relaxation rates
+indicate that the system is in an extended critical regime and the observed
+relaxation is actually dynamic.",2106.03704v3
+2021-06-09,A 2D front-tracking Lagrangian model for the modeling of anisotropic grain growth,"Grain growth is a well-known and complex phenomenon occurring during
+annealing of all polycrystalline materials. Its numerical modeling is a complex
+task when anisotropy sources such as grain orientation and grain boundary
+inclination have to be taken into account. This article presents the
+application of the front-tracking methodology ToRealMotion introduced in
+previous works, to the context of anisotropic grain boundary motion at the
+mesoscopic scale. The new formulation of boundary migration can take into
+account any source of anisotropy both at grain boundaries as well as at
+multiple junctions (MJs) (intersection point of three or more grain
+boundaries). Special attention is given to the decomposition of high-order MJs
+for which an algorithm is proposed based on local grain boundary energy
+minimisation. Numerical tests are provided using highly heterogeneous
+configurations, and comparisons with a recently developed Finite-Element
+Level-Set (FE-LS) approach are given. Finally, the computational performance of
+the model will be studied comparing the CPU-times obtained with the same model
+but in an isotropic context.",2106.04892v2
+2021-06-13,Theory of anisotropic superfluid He-4 counterflow turbulence,"We develop an analytic theory of strong anisotropy of the energy spectra in
+the thermally-driven turbulent counterflow of superfluid He-4. The key
+ingredients of the theory are the three-dimensional differential closure for
+the vector of the energy flux and the anisotropy of the mutual friction force.
+We suggest an approximate analytic solution of the resulting energy-rate
+equation, which is fully supported by the numerical solution. The
+two-dimensional energy spectrum is strongly confined in the direction of the
+counterflow velocity. In agreement with the experiment, the energy spectra in
+the direction orthogonal to the counterflow exhibit two scaling ranges: a
+near-classical non-universal cascade-dominated range and a universal critical
+regime at large wavenumbers. The theory predicts the dependence of various
+details of the spectra and the transition to the universal critical regime on
+the flow parameters.
+  This article is a part of the theme issue 'Scaling the turbulence edifice'.",2106.07014v1
+2021-06-15,Magnetic properties and phase diagrams of the ferrimagnetic triangular nanotube with core-shell structure: A Monte Carlo study,"Monte Carlo simulation has been employed to investigate the magnetic
+properties and phase diagrams of ferrimagnetic mixed-spin (1/2, 1) triangular
+Ising nanotube with core-shell structure. In particular, the effect of the
+exchange couplings and the temperature on the magnetic and thermodynamic
+properties, hysteresis loops as well as the compensation temperature have been
+discussed in detail. Moreover, the effects of the single-ion anisotropy, as
+well as external magnetic field, have been examined. The threshold values of
+the exchange couplings and single-ion anisotropy have been found, determining
+whether the system exhibits a compensation temperature. We have found that the
+appearance of the compensation temperature is strongly linked with the system
+parameters. Moreover, we have obtained the double and triple hysteresis loops
+for certain physical parameters in the considered magnetic system.",2106.08397v1
+2021-06-20,In-plane anisotropic quantum confinement effect in ultrasmall SnS sheets,"Black phosphorus (BP) analogous tin(II) sulfide (SnS) has recently emerged as
+an attractive building block for electronic devices due to its highly
+anisotropic response. Two-dimensional (2D) SnS has shown to exhibit in-plane
+anisotropy in optical and electrical properties. However, the limitations in
+growing ultrasmall structures of SnS hinder the experimental exploration of
+anisotropic behavior in low dimension. Here, we present an elegant approach of
+synthesizing highly crystalline nanometer-sized SnS sheets. Ultrasmall SnS
+exhibits two distinct valleys along armchair and zig-zag directions due to
+in-plane structural anisotropy like bulk SnS. We show that in such SnS
+nanosheet dots, the band gaps corresponding to two valleys are increased due to
+quantum confinement effect. We particularly observe that SnS quantum dots (QDs)
+show excitation energy dependent photoluminescence (PL), which originates from
+the two nondegenerate valleys. Our work may open up an avenue to show the
+potential of SnS QDs for new functionalities in electronics and
+optoelectronics.",2106.10763v1
+2021-06-24,Redshift-space fluctuations in stochastic gravitational wave background,"We study the redshift-space fluctuations induced by a stochastic
+gravitational wave background (SGWB) via the Sachs-Wolfe effect. The
+redshift-space fluctuations can be encapsulated in a line-of-sight integral
+that is useful for studying the imprint of short-wavelength gravitational waves
+on the cosmic microwave background (CMB) anisotropy. We thus derive constraints
+on the SGWB from small-scale CMB anisotropy measurements. Our results reproduce
+the constraint on the short-wavelength SGWB, previously derived from the Planck
+and BICEP/Keck array CMB data with a CMB Boltzmann numerical code. Furthermore,
+we improve the constraint and extend it to shorter wavelengths by using the CMB
+measurements made by the Atacama Cosmology Telescope and the South Pole
+Telescope. Also, the integral provides us with a precise redshift fluctuation
+correlation between a pair of pulsars in pulsar timing measurements, which
+conveniently incorporates the effect of the pulsar term into a small-angle
+correlation. We further discuss the observation of pulsar pairs in globular
+clusters to look for this small-angle correlation.",2106.12843v3
+2021-06-30,Confined Magnons,"Magnetic structures are known to possess magnon excitations confined to their
+surfaces and interfaces, but these spatially localized modes are often not
+resolved in spectroscopy experiments. We develop a theory to calculate the
+confined magnon spectra and its associated spin scattering function, which is
+the physical observable in neutron and electron scattering, and a proxy for
+photon spectroscopy based on X-ray, Raman and THz sources. We show that extra
+anisotropy at the surface or interface plays a key role in magnon confinement.
+We obtain analytical expressions for the confinement length scale, and show
+that it is qualitatively similar for ferromagnets and antiferromagnets in
+dimension d>=2. For d=1 we find remarkable differences between ferromagnetic
+and antiferromagnetic models. The theory indicates the presence of several
+confined magnon resonances in addition to the usual magnons thought to explain
+the excitations of magnetic nanostructures. Detecting these modes may elucidate
+the impact of the interface on spin anisotropy and magnetic order.",2106.15771v2
+2021-07-01,"Anisotropic Upper Critical Field, Seebeck and Nernst Coefficient in Nb0.20Bi2Se3 Topological Superconductor","We present the magneto-transport and the thermoelectric (Seebeck and Nernst
+coefficient) studies of the Nb-doped Bi2Se3 topological superconductor. The
+angle-dependent magnetoresistance study highlights the anisotropy in the upper
+critical field (Hc2) with the anisotropy parameter Gamma ~1.2. We observed a
+gradual decrease in low-temperature Hall resistivity on the application of
+magnetic field like any conventional superconductor, instead of the finite Hall
+resistivity which was linked to the chiral superconducting phase. The estimated
+value of the carrier concentration (~ 10^19 cm-3) for Nb0.2Bi2Se3 is one order
+larger than for Bi2Se3. Doping of Nb shows a significant decrease in the
+Seebeck coefficient value and the estimated Fermi temperature of the
+three-dimensional Fermi surface at the centre of Brillouin zone in the
+zero-temperature limit enhances by ~4 times in comparison to pristine Bi2Se3.
+We have observed a large value (~2.3 micro V K-1 T-1) of Nernst coefficient for
+Bi2Se3 at room temperature which decreases with Nb doping ( ~0.5 micro V K-1
+T-1).",2107.00432v1
+2021-07-02,Deformation mechanisms of Mg-Ca-Zn alloys studied by means of micropillar compression tests,"The effect of Ca and Zn in solid solution on the critical resolved shear
+stress (CRSS) of <a> basal slip, tensile twinning and <c+a> pyramidal slip in
+Mg alloys has been measured through compression tests on single crystal
+micropillars with different orientations. The solute atoms increased the CRSS
+for basal slip to ~ 13.5 MPa, while the CRSS for pyramidal slip was lower than
+85 MPa, reducing significantly the plastic anisotropy in comparison with pure
+Mg. Moreover, the CRSSs for twin nucleation and growth were very similar (~ 37
+MPa) and the large value of the CRSS for twin growth hindered the growth of
+twins during thermo-mechanical processing. Finally, evidence of <a> prismatic
+slip and cross-slip between basal and prismatic dislocations was found. It is
+concluded that the reduction of plastic anisotropy, the activation of different
+slip systems and cross-slip and the weak basal texture promoted by the large
+CRSS for twin growth are responsible for the improved ductility and formability
+of Mg-Ca-Zn alloys.",2107.00878v1
+2021-07-08,Chiral domain wall dynamics in magnetic heterostructures with bulk Dzyaloshinskii-Moriya interactions,"In this work, dynamics of chiral domain walls in long and narrow magnetic
+heterostructures based on non-centrosymmetric chiral magnets with bulk
+Dzyaloshinskii-Moriya interactions (DMI) and perpendicular magnetic anisotropy
+is systematically investigated. The driving forces can be out-of-plane magnetic
+fields and in-plane currents, correspondingly both steady and precessional
+flows are considered. Their dividing points (the Walker critical field and
+current density) are obtained as functions of bulk DMI strength
+($D_{\mathrm{b}}$) and the ratio ($\kappa$) of total (crystalline plus shape)
+anisotropy in the hard axis over that in the easy one. When far beyond Walker
+breakdown, the dependence curve of wall velocity on external in-plane bias
+field takes parabolic shape around the compensation point where the total
+in-plane field disappears. The center shift is determined by $D_{\mathrm{b}}$,
+$\kappa$, and the wall's topological charge, thus can be used to measure the
+bulk DMI strength in chiral magnets.",2107.03586v1
+2021-07-10,The field-angle anisotropy of proximate Kitaev systems under an in-plane magnetic field,"We have investigated the field-angle behaviors of magnetic excitations under
+an in-plane magnetic field for proximate Kitaev systems. By employing the exact
+diagonalization method in conjunction with the linear spin wave theory, we have
+demonstrated that the magnetic excitation gap in the polarized phase is
+determined by the magnon excitation at $M$ points and has a strong anisotropy
+with respect to the field direction in the vicinity of the critical field
+limit. The specific heat from this magnon excitation bears qualitatively the
+same anisotropic behaviors as expected one for the non-Abelian spin liquid
+phase in the Kitaev model and experimentally observed one of the intermediate
+phases in $\alpha$-RuCl$_3$.",2107.04785v2
+2021-07-17,Magnetic anisotropy and critical behavior of the quaternary van der Waals ferromagnetic material $\bf CrGe_δSi_{1-δ}Te_3$,"Recently, two-dimensional ferromagnetism in the family of Chromium compounds
+$\rm CrXTe_3 (X=Si, Ge)$ has attracted a broad research interest. Despite the
+structural similarity in $\rm CrTe_6$ octahedra, the size effect of inserted Ge
+or Si dimer contributes to significant differences in magnetism. Here, we
+report a new quaternary van der Waals ferromagnetic material $\rm
+CrGe_{\delta}Si_{1-\delta}Te_3$ synthesized by flux method. Ge substitution in
+Si site results in the lattice expansion, further increasing the Curie
+temperature and reducing the magnetic anisotropy. The critical behavior of $\rm
+Cr_{0.96}Ge_{0.17}Si_{0.82}Te_3$ has been studied by specific heat as well as
+magnetization measurements. And the extracted critical exponents are
+self-consistent and well-obeying the scaling laws, which are closer to the 2D
+Ising model with interaction decaying as $J(r)\approx r^{-3.44}$.",2107.08222v1
+2021-07-17,Collective modes in anisotropic plasmas,"We study collective modes in anisotropic plasmas of quarks and gluons using a
+quasi-particle picture and a hard loop approximation. We use a general class of
+anisotropic distribution functions, and we consider chirally asymmetric
+systems. We introduce a complete tensor basis to decompose the gluon
+polarization tensor into a set of nine scalar functions. We derive and solve
+the corresponding dispersion equations. Imaginary modes are particularly
+important because of their potential influence on plasma dynamics. We explore
+in detail their dependence on the chiral chemical potential and the parameters
+that characterise the anisotropy of the system. We show that our generalized
+distributions produce dispersion relations that are much richer in structure
+than those obtained with a simple one parameter deformation of an isotropic
+distribution. In addition, the size and domain of the imaginary solutions are
+enhanced, relative to those obtained with a one parameter deformation. Finally,
+we show that the influence of even a very small chiral chemical potential is
+significantly magnified when anisotropy is present.",2107.08229v2
+2021-07-23,Two-body Wigner molecularization in asymmetric quantum dot spin qubits,"Coulomb interactions strongly influence the spectrum and the wave functions
+of few electrons or holes confined in a quantum dot. In particular, when the
+confinement potential is not too strong, the Coulomb repulsion triggers the
+formation of a correlated state, the Wigner molecule, where the particles tend
+to split apart. We show that the anisotropy of the confinement potential
+strongly enhances the molecularization process and affects the performances of
+quantum-dot systems used as spin qubits. Relying on analytical and numerical
+solutions of the two-particle problem -- both in a simplified single-band
+approximation and in realistic setups -- we highlight the exponential
+suppression of the singlet-triplet gap with increasing anisotropy. We compare
+the molecularization effects in different semiconductor materials and discuss
+how they specifically hamper Pauli spin blockade readout and reduce the
+exchange interactions in two-qubit gates.",2107.11117v2
+2021-07-23,Supershear surface waves reveal prestress and anisotropy of soft materials,"Surface waves play important roles in many fundamental and applied areas from
+seismic detection to material characterizations. Supershear surface waves with
+propagation speeds greater than bulk shear waves have recently been reported,
+but their properties are not well understood. In this Letter, we describe
+theoretical and experimental results on supershear surface waves in rubbery
+materials. We find that supershear surface waves can be supported in
+viscoelastic materials with no restriction on the shear quality factor.
+Interestingly, the effect of prestress on the speed of the supershear surface
+wave is opposite to that of the Rayleigh surface wave. Furthermore, anisotropy
+of material affects the supershear wave much more strongly than the Rayleigh
+surface wave. We offer heuristic interpretation as well as theoretical
+verification of our experimental observations. Our work points to the potential
+applications of supershear waves for characterizing the bulk mechanical
+properties of soft solid from the free surface.",2107.11482v1
+2021-07-29,Fine structure of the nonlinear Drude weights in the spin-1/2 XXZ chain,"We study nonlinear Drude weights (NLDWs) for the spin-1/2 XXZ chain in the
+critical regime at zero temperature. The NLDWs are generalizations of the
+linear Drude weight. Via the nonlinear extension of the Kohn formula, they can
+be read off from higher-order finite-size corrections to the ground-state
+energy in the presence of a $U(1)$ magnetic flux. The analysis of the
+ground-state energy based on the Bethe ansatz reveals that the NLDWs exhibit
+convergence, power-law, and logarithmic divergence, depending on the anisotropy
+parameter $\Delta$. We determine the convergent and power-law divergent
+regions, which depend on the order of the response $n$. Then, we examine the
+behavior of the NLDWs at the boundary between the two regions and find that
+they converge for $n=0, 1, 2$ $({\rm mod}~4)$, while they show logarithmic
+divergence for $n=3$ $({\rm mod}~4)$. Furthermore, we identify particular
+anisotropies $\Delta=\cos(\pi r/(r+1))$ ($r=1,2, 3,\ldots$) at which the NLDW
+at any order $n$ converges to a finite value.",2107.13784v3
+2021-07-31,Constant-roll $f(R)$ inflation compared with Cosmic Microwave Background anisotropies and swampland criteria,"Inflationary models derived from $f(R)$ gravity, where the scalaron rolls
+down with a constant rate from the top to the minimum of the effective
+potential, are considered. Specifically, we take into account three $f(R)$
+models \textit{i.e.}\,Starobinsky $R^{2}$, $R^{2p}$ and the logarithmic
+corrected models. We compare the inflationary parameters derived from the
+models with the observational data of CMB anisotropies \textit{i.e.} the Planck
+and Keck/array datasets in order to find observational constraints on the
+parameters space. We find that although our $f(R)$ constant-roll models for
+$\gamma=0$ show observationally acceptable values of $r$, they do not predict
+favoured values of the spectral index. In particular, we have $n_{s}>1$ for the
+Starobinsky $R^{2}$ and $R^{2p}$ models and $0.996<n_{s}<0.999$ for logarithmic
+model. Finally, we study the models from the point of view of Weak Gravity
+Conjecture adopting the swampland criteria.",2108.00175v2
+2021-08-09,First-principles based simulations of electronic transmission in ReS$_{2}$/WSe$_{2}$ and ReS$_{2}$/MoSe$_{2}$ type-II vdW heterointerfaces,"Electronic transmission in monolayer ReS$_{2}$ and ReS$_{2}$ based van der
+Waals (vdW) heterointerfaces are studied here. Since ReS$_{2}$/WSe$_{2}$ and
+ReS$_{2}$/MoSe$_{2}$ type-II vdW heterostructures are suitable for near
+infrared (NIR)/short-wave infrared (SWIR) photodetection, the role of
+interlayer coupling at the heterointerfaces is examined in this work. Besides,
+a detailed theoretical study is presented employing density functional theory
+(DFT) and nonequilibrium Green's function (NEGF) combination to analyse the
+transmission spectra of the two-port devices with ReS$_{2}$/WSe$_{2}$ and
+ReS$_{2}$/MoSe$_{2}$ channels and compare the near-equilibrium conductance
+values.Single layer distorted1T ReS$_{2}$ exhibits formation of parallel chains
+of 'Re' - 'Re' bonds, leading to in-plane anisotropy. Owing to this structural
+anisotropy, the charge carrier transport is very much orientation dependent in
+ReS$_{2}$. Therefore, this work is further extended to investigate the role of
+clusterized 'Re' atoms in electronic transmission.",2108.04341v1
+2021-08-13,Model of the thermoelectric properties of anisotropic organic semiconductors,"A model of charge hopping transport that accounts for anisotropy of localized
+states and Coulomb interaction between charges is proposed. For the anisotropic
+localized states the degree of orientation relates exponentially to the ratio
+of conductivities in parallel and perpendicular directions, while the ratio of
+Seebeck coefficients stays nearly unaffected. However, the ratio of Seebeck
+coefficients increases if Coulomb interaction is screened stronger in a
+direction parallel to the predominant orientation of the localized states. This
+implies two different physical mechanisms responsible for the anisotropy of
+thermoelectric properties in the hopping regime: electronic state localization
+for conductivities, and screening for Seebeck coefficients. This provides
+explanation for recent experimental findings on tensile drawn and ribbed
+polymer films.",2108.06097v2
+2021-08-18,Magnetoelastic coupling enabled tunability of magnon spin current generation in 2D antiferromagnets,"We theoretically investigate the magnetoelastic coupling (MEC) and its effect
+on magnon transport in two-dimensional antiferromagnets with a honeycomb
+lattice. MEC coeffcient along with magnetic exchange parameters and spring
+constants are computed for monolayers of transition metal trichalcogenides with
+N\'eel order ($\text{MnPS}_3$ and $\text{VPS}_3$) and zigzag order
+($\text{CrSiTe}_3$, $\text{NiPS}_3$ and $\text{NiPSe}_3$) by $ab$ $initio$
+calculations. Using these parameters, we predict that the spin-Nernst
+coefficient is significantly enhanced due to magnetoelastic coupling. Our study
+shows that although Dzyaloshinskii-Moriya interaction can produce spin Nernst
+effect in these materials, other mechanisms such as magnon-phonon coupling
+should be taken into account. We also demonstrate that the magnetic anisotropy
+is an important factor for control of magnon-phonon hybridization and
+enhancement of the Berry curvature and thus the spin-Nernst coefficient. Our
+results pave the way towards gate tunable spin current generation in 2D magnets
+by SNE via electric field modulation of MEC and anisotropy.",2108.07999v1
+2021-08-24,Engineering Purcell factor anisotropy for dark and bright excitons in two dimensional semiconductors,"Tightly bound dark excitons in atomically thin semiconductors can be used for
+various optoelectronic applications including light storage and quantum
+communication. Their optical accessibility is however limited due to their
+out-of-plane transition dipole moment. We thus propose to strengthen the
+coupling of dark excitons in two dimensional materials with out-of-plane
+resonant modes of a cavity at room temperature, by engineering the anisotropy
+in the Purcell factor. A silica micro-disk characterised by high confinement of
+light in small modal volume, high Q-factor and free spectral range is used to
+couple to the excitons in monolayer transition metal dichalcogenides. We show
+numerically that the tapering of sidewalls of the micro-disk is an extremely
+versatile route for achieving the selective coupling of whispering gallery
+modes to light emitted from out-of-plane dipoles to the detriment of that from
+in-plane ones for four representative monolayer transition metal
+dichalcogenides.",2108.10680v1
+2021-08-25,Pump-induced terahertz anisotropy in bilayer graphene,"We investigate the intraband nonlinear dynamics in doped bilayer graphene in
+the presence of strong, linearly-polarized, in-plane terahertz fields. We
+perform degenerate pump-probe experiments with 3.4 THz fields on doped bilayer
+graphene at low temperature (12 K) and find that when the pump is co-polarized
+with the probe beam, the differential pump-probe signal is almost double that
+found in the cross-polarized case. We show that the origin of this pump-induced
+anisotropy is the difference in the average electron effective mass in the
+probe direction when carriers are displaced in k-space by the pump either
+parallel or perpendicular to the direction of the probe polarization. We model
+the system using both a simple semiclassical model and a Boltzmann equation
+simulation of the electron dynamics with phenomenological scattering and find
+good qualitative agreement with experimental results.",2108.11183v3
+2021-09-01,Anisotropic Stars in 4D Einstein-Gauss-Bonnet Gravity,"The current trend concerning dense matter physics at sufficiently high
+densities and low temperatures is expected to behave as a degenerate Fermi gas
+of quarks forming Cooper pairs, namely a color superconductor, in the core of
+compact objects. In this context, we study the anisotropy of quark stars (QSs)
+assuming the internal composition to be comprised of homogeneous, charge
+neutral 3-flavor interacting quark matter with $\mathcal{O}(m_s^4)$
+corrections. Using the equation of state (EoS) with the
+Tolmann-Oppenheimer-Volkoff (TOV) structure equations, we perform numerical
+calculation for quark stars and determine the maximum mass-radius relation in
+the context of $4D$ Einstein-Gauss-Bonnet (EGB) gravity. In particular, we
+consider the effects of Gauss-Bonnet (GB) coupling constant on the diagrams
+related to mass-radius $(M-R)$ relation and the mass-central mass density
+$(M-\rho_c)$ relation of QSs. We pay particular attention to the influence of
+the anisotropy in the equilibrium and stability of strange stars. We also study
+the other properties of QSs related to compactness and binding energy.
+Interestingly, our result provides circumstantial evidence in favor of
+super-massive pulsars in $4D$ EGB gravity.",2109.00195v1
+2021-09-06,Pitch Angle Anisotropy Controls Particle Acceleration and Cooling in Radiative Relativistic Plasma Turbulence,"Nature's most powerful high-energy sources are capable of accelerating
+particles to high energy and radiate it away on extremely short timescales,
+even shorter than the light crossing time of the system. It is yet unclear what
+physical processes can produce such an efficient acceleration, despite the
+copious radiative losses. By means of radiative particle-in-cell simulations,
+we show that magnetically dominated turbulence in pair plasmas subject to
+strong synchrotron cooling generates a nonthermal particle spectrum with a hard
+power-law range (slope $p \sim 1$) within a few eddy turnover times. Low
+pitch-angle particles can significantly exceed the nominal radiation-reaction
+limit, before abruptly cooling down. The particle spectrum becomes even harder
+($p < 1$) over time owing to particle cooling with an energy-dependent
+pitch-angle anisotropy. The resulting synchrotron spectrum is hard ($\nu F_\nu
+\propto \nu^s$ with $s \sim 1$). Our findings have important implications for
+understanding the nonthermal emission from high-energy astrophysical sources,
+most notably the prompt phase of gamma-ray bursts and gamma-ray flares from the
+Crab nebula.",2109.02666v1
+2021-09-09,Adjustable 3D magnetic configuration in ferrimagnetic multilayers with competing interactions visualized by soft X-ray vector tomography,"Soft X-ray magnetic vector tomography has been used to visualize with
+unprecedented detail and solely from experimental data the 3D magnetic
+configuration of a ferrimagnetic Gd12Co88/Nd17Co83/Gd24Co76 multilayer with
+competing anisotropy, exchange and magnetostatic interactions at different
+depths. The trilayer displays magnetic stripe domains, arranged in a chevron
+pattern, which are imprinted from the central Nd17Co83 into the bottom Gd12Co88
+layer with a distorted closure domain structure across the thickness. Near the
+top Gd24Co76 layer, local exchange springs with out-of-plane magnetization
+reversal, modulated ripple patterns and magnetic vortices and antivortices
+across the thickness are observed. The detailed analysis of the magnetic
+tomogram shows that the effective strength of the exchange spring at the
+NdCo/GdCo interface can be finely tuned by GdxCo1-x composition and anisotropy
+(determined by sample fabrication) and in-plane stripe orientation
+(adjustable), demonstrating the capability of 3D magnetic visualization
+techniques in magnetic engineering research.",2109.04064v1
+2021-09-13,Pseudospin-Triplet Pairing in Iron-Chalcogenide Superconductors,"We study superconductivity of electron systems with both spin and
+pseudospin-1/2 degrees of freedom. By solving linearized gap equations, we
+derive a weak coupling criterion for the even-parity spin-singlet
+pseudospin-triplet pairing. It can generally mix with the on-site s-wave
+pairing since both of them belong to the same symmetry representation
+($A_{1g}$) and their mixture could naturally give rise to anisotropic
+intra-band pairing gap functions with or without nodes. This may directly
+explain why some of the iron-chalcogenide superconductors are fully gapped
+(e.g. FeSe thin film) and some have nodes (e.g. LaFePO and LiFeP). We also find
+that the anisotropy of gap functions can be enhanced when the principal
+rotation symmetry is spontaneously broken in the normal state such as
+nematicity, and the energetic stabilization of pseudospin-triplet pairings
+indicates the coexistence of nematicity and superconductivity. This could be
+potentially applied to bulk FeSe, where gap anisotropy has been experimentally
+observed.",2109.06039v4
+2021-09-15,Turbulent magneto-genesis in a collisionless plasma,"We investigate an efficient mechanism for generating magnetic fields in
+turbulent, collisionless plasmas. By using fully kinetic, particle-in-cell
+simulations of an initially non-magnetized plasma, we inspect the genesis of
+magnetization, in a nonlinear regime. The complex motion is initiated via a
+Taylor-Green vortex, and the plasma locally develops strong electron
+temperature anisotropy, due to the strain tensor of the turbulent flow.
+Subsequently, in a domino effect, the anisotropy triggers a Weibel instability,
+localized in space. In such active wave-particle interaction regions, the
+magnetic field seed grows exponentially and spreads to larger scales due to the
+interaction with the underlying stirring motion. Such a self-feeding process
+might explain magneto-genesis in a variety of astrophysical plasmas, wherever
+turbulence is present.",2109.07432v1
+2021-09-16,Dynamics of microstructure anisotropy and rheology of soft jammed suspensions,"We explore the rheology predicted by a recently proposed constitutive model
+for jammed suspensions of soft elastic particles derived from particle-level
+dynamics [Cuny et al., Phys. Rev. Lett. 127, 218003 (2021)]. Our model predicts
+that the orientation of the anisotropy of the microstructure, governed by an
+interplay between advection and contact elasticity, plays a key role at
+yielding and in flow. It generates normal stress differences contributing
+significantly to the yield criterion and Trouton ratio. It gives rise to
+non-trivial transients such as stress overshoots in step increases of shear
+rate, residual stresses after flow cessation and power-law decay of the shear
+rate in creep. Finally, it explains the collapse of storage modulus as measured
+in parallel superposition for a yielded suspension.",2109.07786v2
+2021-09-20,Random magnetic anisotropy in a new compound $\mbox{Sm}_2\mbox{Ag}\mbox{Si}_3$,"We report the experimental study on the structural and magnetic properties of
+a new ternary intermetallic compound $\mathrm{Sm_2AgSi_3}$. The properties of
+the sample were investigated in detail by X-ray diffraction, dc-magnetization,
+and heat capacity measurements. The polycrystalline compound of
+$\mathrm{Sm_2AgSi_3}$ crystallizes in the $\mathrm{ThSi_2}$-type tetragonal
+structure (space group ${I_{4_1}/amd}$). The temperature-dependent
+dc-magnetization and heat capacity results demonstrate that the compound
+undergoes ferromagnetic behaviour with a Curie temperature ($T_C$) of 14 K. The
+large coercive field in hysteresis loops and the thermomagnetic irreversibility
+in the ferromagnetic region revealed that the compound exhibits a large
+magnetic anisotropy. The magnitude of the applied field and the coercivity
+obtained from the M-H loops corroborate with the thermomagnetic irreversibility
+in the magnetization data. The magnetic contribution of the heat capacity
+reveals a broad Schottky-type anomaly above $T_C$, due to the presence of the
+crystal electric field effect of $\mathrm{Sm^{3+}}$ in $\mathrm{Sm_2AgSi_3}$.",2109.09608v1
+2021-09-21,Analysis of the directionality on periodic materials,"There is an increasing interest in the study of metamaterials and periodic
+materials across disciplines. These are anisotropic and their properties
+present directionality. For example, the wave speed depends on the propagation
+direction. Furthermore, they are heterogeneous, and their directionality
+depends on their spectra. Common approaches to describe anisotropy have been
+used in the large-wavelength approximation corresponding to static properties.
+Here we present an anisotropy measure based on the dynamic behavior. It
+receives dispersion surfaces from Bloch analyses and outputs a curve/surface
+with bulk directionality encoded on it. We present results for elastodynamics,
+but it is applicable to other phenomena.",2109.09893v4
+2021-09-21,Influence of a spatial anisotropy on presence of the intermediate one-half magnetization plateau of a spin-1/2 Ising-Heisenberg branched chain,"A spin-1/2 Ising-Heisenberg branched chain constituted by regularly
+alternating Ising spins and Heisenberg dimers involving an additional side
+branching is exactly solved in a magnetic field by the transfer-matrix method.
+The spin-1/2 Ising-Heisenberg branched chain involves two different Ising and
+one Heisenberg coupling constants. The overall ground-state phase diagram is
+formed by three different ground states emergent depending on a mutual
+interplay between the magnetic field and three considered coupling constants:
+the modulated quantum antiferromagnetic phase, the quantum ferrimagnetic phase,
+and the classical ferromagnetic phase. It is shown that the interaction
+anisotropy connected to two different Ising coupling constants substantially
+influences a breakdown of the intermediate one-half magnetization plateau,
+which represents a macroscopic manifestation of the quantum ferrimagnetic
+phase.",2109.10026v1
+2021-09-22,Zero Poisson' s Ratio and Suppressed Mechanical Anisotropy in BP/SnSe Van der Waals Heterostructure: A First-principles Study,"Black phosphorene and its analogs have attracted intensive attention due to
+their unique puckered structures, anisotropic characteristics, and negative
+Poisson's ratio. The van der Waals heterostructures assembly by stacking
+different materials may show novel physical properties which the parent
+materials don't possess. In this work, the first-principles calculations were
+performed to study the mechanical properties of the BP/SnSe van der Waals
+heterostructure. Interestingly, a near-zero Poisson's ratio vzx was found in
+BP/SnSe heterostructure. In addition, compared to the parent materials BP and
+SnSe with strong in-plane anisotropic mechanical properties, the BP/SnSe
+heterostructure shows strongly suppressed anisotropy. Our findings suggest that
+the vdW heterostructure could show quite different mechanical properties from
+the parent materials and provide new opportunities for the mechanical
+applications of the heterostructures.",2109.10494v1
+2021-09-27,Magnetization tunable Weyl states in EuB6,"The interplay between magnetism and topological band structure offers
+extraordinary opportunities to realize rich exotic magnetic topological phases
+such as axion insulators, Weyl semimetals, and quantum anomalous Hall
+insulators, which therefore has attracted fast growing research interest. The
+rare-earth hexaborides EuB6 represents an interesting magnetic topological
+phase with tunable magnetizations along different crystallographic directions,
+while the correlation with the topological properties remains scarcely
+explored. In this work, combining magnetotransport measurements and first
+principles calculations, we demonstrate that EuB6 exhibits versatile magnetic
+topological phases along different crystallographic directions, which tightly
+correlate with the varied magnetizations. Moreover, by virtue of the weak
+magneto-crystalline anisotropy and the relatively strong coupling between the
+local magnetization and the conduction electrons, we show that the magnetic
+ground state of the system can be directly probed by the anisotropy in the
+magnetotransport properties. Our work thus introduces an excellent platform to
+study the rich topological phases that are tunable by magnetic orders.",2109.12823v1
+2021-10-03,Giant Spin Lifetime Anisotropy and Spin-Valley Locking in Silicene and Germanene from First-Principles Density-Matrix Dynamics,"Through First-Principles real-time Density-Matrix (FPDM) dynamics
+simulations, we investigate spin relaxation due to electron-phonon and
+electron-impurity scatterings with spin-orbit coupling in two-dimensional Dirac
+materials - silicene and germanene, at finite temperatures and under external
+fields. We discussed the applicability of conventional descriptions of spin
+relaxation mechanisms by Elliott-Yafet (EY) and D'yakonov-Perel' (DP) compared
+to our FPDM method, which is determined by a complex interplay of intrinsic
+spin-orbit coupling, external fields, and electron-phonon coupling strength,
+beyond crystal symmetry. For example, the electric field dependence of spin
+relaxation time is close to DP mechanism for silicene at room temperature, but
+rather similar to EY mechanism for germanene. Due to its stronger spin-orbit
+coupling strength and buckled structure in sharp contrast to graphene,
+germanene has a giant spin lifetime anisotropy and spin valley locking effect
+under nonzero Ez and relatively low temperature. More importantly, germanene
+has extremely long spin lifetime (~100 ns at 50 K) and ultrahigh carrier
+mobility, which makes it advantageous for spin-valleytronic applications.",2110.01128v1
+2021-10-04,Anomalous temperature dependence of phonon pumping by ferromagnetic resonance in Co/Pd multilayers with perpendicular anisotropy,"We demonstrate the pumping of phonons by ferromagnetic resonance in a series
+of [Co(0.8 nm)/Pd(1.5 nm)]$_n$ multilayers ($n =$ 6, 11, 15, and 20) with large
+magnetostriction and perpendicular magnetic anisotropy. The effect is shown
+using broadband ferromagnetic resonance over a range of temperatures (10 to 300
+K), where a resonant damping enhancement is observed at frequencies
+corresponding to standing wave phonons across the multilayer. The strength of
+this effect is enhanced by approximately a factor of 4 at 10 K compared to room
+temperature, which is anomalous in the sense that the temperature dependence of
+the magnetostriction predicts an enhancement that is less than a factor of 2.
+Lastly, we demonstrate that the damping enhancement is correlated with a shift
+in the ferromagnetic resonance field as predicted quantitatively from linear
+response theory.",2110.01714v1
+2021-10-05,The impact of defects on excitations in two-dimensional bipartite uniaxial antiferromagnet insulators,"We address scatterings of spin waves off uncorrelated defects in
+two-dimensional (2D) easy-axis antiferromagnet (AFM) insulators. Although an
+onsite magnetic anisotropy leads gapped Goldstone modes, such that a long range
+(AFM) order can be established in 2D, lattice imperfections tend to weaken, and
+eventually destroy the magnetic ordering. Here, the impact of defects is
+considered within two limits, single and multiple defects. Using Green's
+function, we perform self consistent simulations to study magnon properties
+such as density of states and lifetime of induced resonances. Our findings show
+that repulsive defects decrease the magnon density of states while attractive
+ones may enhance it. We provide a comprehensive analysis of how defects can
+result in a reduction and even closing, the anisotropy induced gap, which
+weakens the long range (AFM) order parameter in the 2D state. We conclude that
+a small concentration of random defects can fill the gap of magnon spectrum.",2110.02045v3
+2021-10-06,Current-Perpendicular-to-Plane Giant Magnetoresistance Effect in van der Waals Heterostructures,"Spin-dependent transport in a full van der Waals (vdW) giant
+magnetoresistance (GMR) junctions with the structure of Fe3GeTe2/XTe2/Fe3GeTe2
+(X = Pt, Pd) has been investigated by using first-principles calculations. The
+ballistic conductance, magnetoresistance (MR) and resistance-area product (RA)
+have been calculated in a current-perpendicular-to-plane (CPP) geometry. A
+giant magnetoresistance of around 2000% and RA less than 0.3 {\Omega} {\mu}m2
+have been found in the proposed vdW CPP GMR. In addition, the spin-orbit
+coupling effect on transport and anisotropy magnetoresistance (AMR) has also
+been investigated. The calculated AMR is found to be around 20% in
+Fe3GeTe2/trilayer-PdTe2/Fe3GeTe2 CPP GMR. Both GMR and AMR in the proposed vdW
+CPP GMR mainly originate from the bulk electronic structure properties of
+Fe3GeTe2. This work demonstrates a vdW CPP GMR with superior advantages
+including perpendicular magnetic anisotropy, large GMR, low RA as well as
+sizable AMR may stimulate future experimental explorations and should be
+appealing for their applications in spintronic devices including magnetic
+sensor and memory.",2110.02535v1
+2021-10-12,Primordial black hole formation for an anisotropic perfect fluid: Initial conditions and estimation of the threshold,"This work investigates the formation of primordial black holes within a
+radiation fluid with an anisotropic pressure. We focus our attention on the
+initial conditions describing cosmological perturbations in the super horizon
+regime, using a covariant form of the equation of state in terms of pressure
+and energy density gradients. The effect of the anisotropy is to modify the
+initial shape of the cosmological perturbations with respect to the isotropic
+case. Using the dependence of the threshold $\delta_\mathrm{c}$ for primordial
+black holes with respect to the shape of cosmological perturbations, we
+estimate here how the threshold is varying with respect to the amplitude of the
+anisotropy. If this variation is large enough it could lead to a significant
+variation of the abundance of PBHs.",2110.05982v4
+2021-10-13,Generalized plasma waves in layered superconductors,"In a layered and strongly anisotropic superconductor the hybrid modes
+provided by the propagation of electromagnetic waves in the matter identify two
+well separate energy scales connected to the large in-plane plasma frequency
+and to the soft out-of-plane Josephson plasmon. Despite the wide interest in
+their detection and manipulation by means of different experimental protocols,
+a unified description of plasma waves valid at arbitrary energy and momentum is
+still lacking. Here we provide a complete description of generalized plasma
+waves in a layered superconductors by taking advantage of their connection to
+the gauge-invariant superconducting phase. We show that the anisotropy of the
+superfluid response leads to two intertwined hybrid light-matter modes with
+mixed longitudinal and transverse character, while a purely longitudinal
+plasmon is only recovered for wavevectors larger than the crossover scale set
+in by the plasma-frequencies anisotropy. Interestingly, below such scale both
+modes appears with equal weight in the physical density response. Our results
+open a promising perspective for plasmonic applications made possible by the
+next-generation spectroscopic techniques able to combine sub-micron momentum
+resolution with THz energy resolution.",2110.06772v1
+2021-10-15,Effects of Quantum Pair Creation and Annihilation on a Classical Exclusion Process: the transverse XY model with TASEP,"We investigate how particle pair creation and annihilation, within the
+quantum transverse XY model, affects the non-equilibrium steady state (NESS)
+and Liouvillian gap of the stochastic Totally Asymmetric Exclusion Process
+(TASEP). By utilising operator quantization we formulate a perturbative
+description of the NESS. Furthermore, we estimate the Liouvillian gap by
+exploiting a Majorana canonical basis as the basis of super-operators. In this
+manner we show that the Liouvillian gap can remain finite in the thermodynamic
+limit provided the XY model anisotropy parameter remains non-zero.
+Additionally, we show that the character of the gap with respect to the
+anisotropy parameter differs depending on the phase of the XY model. The change
+of character corresponds to the quantum phase transition of the XY model.",2110.08283v1
+2021-10-19,Ising and XY paramagnons in two-dimensional 2H-NbSe$_2$,"Paramagnons are the collective modes that govern the spin response of nearly
+magnetic conductors. In some cases they mediate electron pairing leading to
+superconductivity. This scenario may occur in 2H-NbSe$_2$ monolayers, that
+feature spin-valley coupling on account of spin-orbit interactions and their
+lack of inversion symmetry. Here we explore spin anisotropy of paramagnons both
+for non-centrosymmetric Kane-Mele-Hubbard models for 2H-NbSe$_2$ monolayers
+described with a DFT-derived tight-binding model. In the infinite wavelength
+limit we find spatially uniform paramagnons with energies around $1$~meV that
+feature a colossal off-plane uniaxial magnetic anisotropy, with quenched
+transversal spin response. At finite wave vectors, longitudinal and transverse
+channels reverse roles: XY fluctuations dominate within a significant portion
+of the Brillouin zone. Our results show that 2H-NbSe$_2$ is close to a
+Coulomb-driven in-plane (XY) spin density wave instability.",2110.09809v2
+2021-10-28,Curved Magnetism in CrI$_3$,"Curved magnets attract considerable interest for their unusually rich phase
+diagram, often encompassing exotic (e.g., topological or chiral) spin states.
+Micromagnetic simulations are playing a central role in the theoretical
+understanding of such phenomena; their predictive power, however, rests on the
+availability of reliable model parameters to describe a given material or
+nanostructure. Here we demonstrate how non-collinear-spin polarized
+density-functional theory can be used to determine the flexomagnetic coupling
+coefficients in real systems. By focusing on monolayer CrI$_3$, we find a
+crossover as a function of curvature between a magnetization normal to the
+surface to a cycloidal state, which we rationalize in terms of effective
+anisotropy and Dzyaloshinskii-Moriya contributions to the magnetic energy. Our
+results reveal an unexpectedly large impact of spin-orbit interactions on the
+curvature-induced anisotropy, which we discuss in the context of existing
+phenomenological models.",2110.15088v3
+2021-10-29,Transport and spectral properties of the XX$+$XXZ diode and stability to dephasing,"We study the transport and spectral property of a segmented diode formed by
+an XX $+$ XXZ spin chain. This system has been shown to become an ideal
+rectifier for spin current for large enough anisotropy. Here we show numerical
+evidence that the system in reverse bias has three different transport regimes
+depending on the value of the anisotropy: ballistic, diffusive and insulating.
+In forward bias we encounter two regimes, ballistic and diffusive. The system
+in forward and reverse bias shows significantly different spectral properties,
+with distribution of rapidities converging towards different functions. In the
+presence of dephasing the system becomes diffusive, rectification is
+significantly reduced, the relaxation gap increases and the spectral properties
+in forward and reverse bias tend to converge. For large dephasing the
+relaxation gap decreases again as a result of Quantum Zeno physics.",2110.15564v3
+2021-11-05,Temperature-driven transition from skyrmion to bubble crystals in centrosymmetric itinerant magnets,"Interplay between itinerant electrons and localized spins in itinerant
+magnets gives rise to a variety of noncoplanar multiple-$Q$ spin textures, such
+as the skyrmion, hedgehog, meron, and vortex. We elucidate that another type of
+multiple-$Q$ state consisting of collinear sinusoidal waves, a magnetic bubble
+crystal, appears at finite temperatures in a centrosymmetric itinerant electron
+system. The results are obtained for the classical Kondo lattice model with
+easy-axis single-ion anisotropy on a triangular lattice by a large-scale
+numerical simulation. We find that a finite-temperature topological phase
+transition between the skyrmion crystal and the bubble crystal occurs by
+changing the temperature. We obtain the minimal key ingredients for inducing
+the finite-temperature transition by analyzing an effective spin model where it
+is shown that the synergy between the multiple-spin interaction and magnetic
+anisotropy plays a significant role.",2111.03202v1
+2021-11-05,Transverse momentum broadening in real-time lattice simulations of the glasma,"The study of jets in heavy-ion collisions provides important information
+about the interaction of partons with the medium that they traverse. The seeds
+of jets are highly energetic partons, which are produced from hard scatterings
+during the collision event. As such, they are affected by all different stages
+of the medium's time evolution, including the glasma, which is the
+pre-equilibrium precursor state of the quark-gluon plasma. Here we report on
+our numerical lattice simulations of partons traversing the boost-invariant,
+non-perturbative glasma as created at the early stages of collisions at RHIC
+and LHC. We find that partons quickly accumulate transverse momentum up to the
+saturation momentum during the glasma stage. Furthermore, we observe an
+interesting anisotropy in transverse momentum broadening of partons with larger
+broadening in the rapidity than in the azimuthal direction. Its origin can be
+related to correlations among the longitudinal color-electric and
+color-magnetic flux tubes in the initial state of the glasma. We compare these
+observations to the semi-analytic results obtained by a weak-field
+approximation, where we also find such an anisotropy in a parton's transverse
+momentum broadening.",2111.03400v1
+2021-11-11,$60^{\circ}$ and $120^{\circ}$ Domain Walls in Epitaxial BaTiO$_{3}$(111)/Co Multiferroic Heterostructures,"We report on domain pattern transfer from a ferroelectric
+BaTiO$_{\mathrm{3}}$ substrate with a $(111)$-orientation of the surface to an
+epitaxial Co film grown on a Pd buffer layer. Spatially modulated interfacial
+strain transfer from ferroelectric/ferroelastic domains and inverse
+magnetostriction in the ferromagnetic film induce stripe regions with a
+modulation of the in-plane uniaxial magnetic anisotropy direction. Using
+spin-polarized low energy electron microscopy, we observe the formation of two
+distinct anisotropy configurations between stripe regions. Moreover, through
+application of a magnetic field parallel or perpendicular to these stripes,
+head-to-head or head-to-tail magnetization configurations are initialized. This
+results in four distinct magnetic domain wall types associated with different
+energies and widths, which in turn affects whether domain pattern transfer can
+be achieved.",2111.06191v1
+2021-11-11,Scale dependent anisotropy of electric field fluctuations in solar wind turbulence,"We study the variation of average powers and spectral indices of electric
+field fluctuations with respect to the angle between average flow direction and
+the mean magnetic field in solar wind turbulence. Cluster spacecraft data from
+the years 2002 and 2007 are used for the present analysis. We perform a scale
+dependent study with respect to the local mean magnetic field using wavelet
+analysis technique. Prominent anisotropies are found for both the spectral
+index and power levels of the electric power spectra. Similar to the magnetic
+field fluctuations, the parallel (or antiparallel) electric fluctuation
+spectrum is found to be steeper than the perpendicular spectrum. However the
+parallel (or antiparallel) electric power is found to be greater than the
+perpendicular one. Below 0.1 Hz, the slope of the parallel electric power
+spectra deviates substantially from that of the total magnetic power spectra,
+supporting the existence of Alfv\'enic turbulence.",2111.06280v1
+2021-11-11,Elastic properties of Janus transition metal dichalcogenide nanotubes from first principles,"We calculate the elastic properties of Janus transition metal dichalcogenide
+(TMD) nanotubes using first principles Kohn-Sham density functional theory
+(DFT). Specifically, we perform electronic structure simulations that exploit
+the cyclic and helical symmetry in the system to compute the Young's moduli,
+Poisson's ratios, and torsional moduli for twenty-seven select armchair and
+zigzag Janus TMD nanotubes at their equilibrium diameters. We find the
+following trend in the moduli values: MSSe > MSTe > MSeTe, while their
+anisotropy with respect to armchair and zigzag configurations has the following
+ordering: MSTe > MSeTe > MSSe. This anisotropy and its ordering between the
+different groups is confirmed by computing the shear modulus from the torsional
+modulus using an isotropic elastic continuum model, and comparing it against
+the value predicted from the isotropic relation featuring the Young's modulus
+and Poisson's ratio. We also develop a model for the Young's and torsional
+moduli of Janus TMD nanotubes based on linear regression.",2111.06446v4
+2021-11-15,Dragging heavy quark in an anisotropic QCD medium beyond the static limit,"Heavy quark dynamics in an anisotropic QCD medium have been analyzed within
+the Fokker-Planck approach. Heavy quark drag force and momentum diffusion
+tensor have been decomposed by employing a general tensor basis for an
+anisotropic medium. Depending upon the relative orientation of the direction of
+the momentum anisotropy of the medium and heavy quark motion, two drag and four
+diffusion coefficients have been estimated in the anisotropic QCD medium. The
+relative significance of different components of drag and momentum diffusion
+coefficients has been explored. The dependence of the angle between the
+anisotropic vector and heavy quark motion to the drag and diffusion
+coefficients has also been studied. Further, the energy loss of heavy quarks
+due to the elastic collisional process in an anisotropic medium has been
+studied. It is seen that the anisotropic contributions to heavy quark transport
+coefficients and its collisional energy loss have a strong dependence on the
+direction and strength of momentum anisotropy in the QCD medium.",2111.07563v1
+2021-11-15,Determination of spin chirality using x-ray magnetic circular dichroism,"A 3-fold symmetric kagome lattice that has negative spin chirality can give a
+non-zero x-ray magnetic circular dichroism (XMCD) signal, despite that the
+total spin moment amounts to zero. This is explained by a hitherto unnoticed
+rule for the rotational symmetry invariance of the XMCD signal. A necessary
+condition is the existence of an anisotropic XMCD signal for the local magnetic
+atom, which can arise from a spin anisotropy either in the ground state or the
+final state. The angular dependence of the XMCD as a function of the beam
+direction has an unusual behavior. The maximum dichroism is not aligned along
+the spin direction, but depends on the relative orientation of the spin with
+respect to the atomic orientation. Therefore, different geometries can result
+in the same angular dependence, and the spin direction can only be determined
+if the atomic orientation is known. The consequences for the x-ray
+magneto-optical sum rules are given. The integrated XMCD signals are
+proportional to the anisotropy in the orbital moment and the magnetic dipole
+term, where the isotropic spin moment drops out.",2111.07690v1
+2021-11-15,Model-free approach to the interpretation of restricted and anisotropic self-diffusion in magnetic resonance of biological tissues,"Magnetic resonance imaging (MRI) is the method of choice for noninvasive
+studies of micrometer-scale structures in biological tissues via their effects
+on the time/frequency-dependent (""restricted"") and anisotropic self-diffusion
+of water. Traditional MRI relies on pulsed magnetic field gradients to encode
+the signal with information about translational motion in the direction of the
+gradient, which convolves fundamentally different aspects-such as bulk
+diffusivity, restriction, anisotropy, and flow-into a single effective
+observable lacking specificity to distinguish between biologically plausible
+microstructural scenarios. To overcome this limitation, we introduce a formal
+analogy between measuring rotational correlation functions and interaction
+tensor anisotropies in nuclear magnetic resonance (NMR) spectroscopy and
+investigating translational motion in MRI, which we utilize to convert data
+acquisition and analysis strategies from NMR of rotational dynamics in
+macromolecules to MRI of diffusion in biological tissues, yielding
+model-independent quantitative metrics reporting on relevant microstructural
+properties with unprecedented specificity. Our model-free approach advances the
+state-of-the-art in microstructural MRI, thereby enabling new applications to
+complex multi-component tissues prevalent in both tumors and healthy brain.",2111.07827v1
+2021-11-16,Quantification of fracture roughness by change probabilities and Hurst exponents,"The objective of the current study is to utilize an innovative method called
+'change probabilities' for describing fracture roughness. In order to detect
+and visualize anisotropy of rock joint surfaces, the roughness of
+one-dimensional profiles taken in different directions is quantified. The
+central quantifiers, 'change probabilities', are based on counting monotone
+changes in discretizations of a profile. These probabilities, which are usually
+varying with the scale, can be reinterpreted as scale-dependent Hurst
+exponents. For a large class of Gaussian stochastic processes change
+probabilities are shown to be directly related to the classical Hurst exponent,
+which generalizes a relationship known for fractional Brownian motion. While
+being related to this classical roughness measure, the proposed method is more
+generally applicable, increasing therefore the flexibility of modeling and
+investigating surface profiles. In particular, it allows a quick and efficient
+visualization and detection of roughness anisotropy and scale dependence of
+roughness.",2111.08661v1
+2021-11-17,Relativistic oblique shocks with ordered or random magnetic fields: tangential field governs,"Relativistic magnetohydrodynamic shocks are efficient particle accelerators,
+often invoked in the models of gamma-ray bursts (GRBs) and shock-powered fast
+radio bursts (FRBs). Most theoretical studies assume a perpendicular shock with
+an ordered magnetic field perpendicular to the shock normal. However, the
+degree of magnetization $\sigma$ and the magnetic field geometry in
+shock-powered GRB/FRB scenarios are still poorly constrained by observations.
+Analogous to the magnetization $\sigma$ associated with the total field
+strength, we define a tangential magnetization $\sigma_\perp$ associated with
+the tangential field component. We explore the jump conditions of magnetized
+relativistic shocks, either with an ordered field of arbitrary inclination
+angle or with a random field of arbitrary anisotropy. In either case, we find
+that the jump conditions of relativistic shocks are governed by the tangential
+magnetization $\sigma_\perp$ instead of the total magnetization $\sigma$,
+insensitive to the inclination angles or the anisotropy of the pre-shock
+magnetic field. The approximated analytical solution developed in this work
+could serve as a quick check for numerical simulations and apply to theoretical
+studies of GRBs/FRBs with a more general field geometry.",2111.09206v2
+2021-11-22,Cycle deformation enabled controllable mechanical polarity of bulk metallic glasses,"Tuning anisotropy in bulk metallic glasses, ideally isotropic, is of
+practical interest in optimizing properties and of fundamental interest in
+understanding the amorphous structure and its instability. By employing the
+quasi-elastic asymmetric mechanical cycling method, we effectively induce the
+mechanical polarity of a model bulk metallic glass, without damaging the sample
+or introducing significant annealing or rejuvenation effects. Moreover, the
+polarized anelastic limit can be well controlled by regulating the amplitude of
+mechanical cycling. Through the atomic-level analysis of nonaffine
+displacement, we find that only plastic atomic rearranged events corresponding
+to the training direction can be exhausted by asymmetric cycling and the
+survived anelastic events dominate the directional anelastic limit. The
+polarized distribution of local yield stress reveals that the mechanical
+polarity is attributed to the plastic-event-healing induced asymmetry of local
+potential energy surface, rather than frozen-in anelastic strain. Furthermore,
+the healing of plastic events associated with the redistribution of local
+residual stress indicates the origin of polarity induced by asymmetric cycling.
+Our study is of fundamental importance, which furthers our understanding of the
+mechanical deformation of metallic glasses and shed some light on the prospects
+for improved properties through induced anisotropy.",2111.11164v1
+2021-11-29,A prediction for anisotropies in the nearby Hubble flow,"We assess the dominant low-redshift anisotropic signatures in the
+distance-redshift relation and redshift drift signals. We adopt
+general-relativistic irrotational dust models allowing for gravitational
+radiation -- the `quiet universe models' -- which are extensions of the silent
+universe models. Using cosmological simulations evolved with numerical
+relativity, we confirm that the quiet universe model is a good description on
+scales larger than those of collapsing structures. With this result, we reduce
+the number of degrees of freedom in the fully general luminosity distance and
+redshift drift cosmographies by a factor of $\sim 2$ and $\sim 2.5$,
+respectively, for the most simplified case. We predict a dominant dipolar
+signature in the distance-redshift relation for low-redshift data, with
+direction along the gradient of the large-scale density field. Further, we
+predict a dominant quadrupole in the anisotropy of the redshift drift signal,
+which is sourced by the electric Weyl curvature tensor. The signals we predict
+in this work should be tested with present and near-future cosmological
+surveys.",2111.14423v1
+2021-11-30,First and second order magnetic anisotropy and damping of europium iron garnet under high strain,"Understanding and tailoring static and dynamic properties of magnetic
+insulator thin films is important for spintronic device applications. Here, we
+grow atomically flat epitaxial europium iron garnet (EuIG) thin films by pulsed
+laser deposition on (111)-oriented garnet substrates with a range of lattice
+parameters. By controlling the lattice mismatch between EuIG and the
+substrates, we tune the strain in EuIG films from compressive to tensile
+regime, which is characterized by X-ray diffraction. Using ferromagnetic
+resonance, we find that in addition to the first-order perpendicular magnetic
+anisotropy which depends linearly on the strain, there is a significant
+second-order one that has a quadratic strain dependence. Inhomogeneous
+linewidth of the ferromagnetic resonance increases notably with increasing
+strain, while the Gilbert damping parameter remains nearly constant (~
+2x10^-2). These results provide valuable insight into the spin dynamics in
+ferrimagnetic insulators and useful guidance for material synthesis and
+engineering of next-generation spintronics applications.",2111.15142v1
+2021-12-07,On transverse momentum broadening in real-time lattice simulations of the glasma and in the weak-field limit,"In these proceedings, we report on our numerical lattice simulations of
+partons traversing the boost-invariant, non-perturbative glasma as created at
+the early stages of collisions at RHIC and LHC. Since these highly energetic
+partons are produced from hard scatterings during heavy-ion collisions, they
+are already affected by the first stage of the medium's time evolution, the
+glasma, which is the pre-equilibrium precursor state of the quark-gluon plasma.
+We find that partons quickly accumulate transverse momentum up to the
+saturation momentum during the glasma stage. Moreover, we observe an
+interesting anisotropy in transverse momentum broadening of partons with larger
+broadening in the rapidity than in the azimuthal direction. Its origin can be
+related to correlations among the longitudinal color-electric and
+color-magnetic flux tubes in the initial state of the glasma. We compare these
+observations to the semi-analytic results obtained by a weak-field
+approximation, where we also find such an anisotropy in a parton's transverse
+momentum broadening.",2112.03883v1
+2021-12-09,Competition between isotropic and strongly anisotropic terms in the impact ionization rate of narrow- and middle-gap cubic semiconductors,"We report on the strong anisotropy of the inter-band process of impact
+ionization in direct-gap cubic semiconductors with either weak or strong
+spin-orbit coupling at low effective temperatures of electron distribution $T$,
+and the crossover to isotropic behavior with increasing $T$. Such anisotropy is
+related to specific mechanism of the impact ionization involving coupling of
+the electron and heavy hole states $\it via$ remote bands, which is vanishing
+for some high-symmetry propagation directions of an initial electron, namely
+$\mathrm{[100]}$ and $\mathrm{[111]}$. At room temperature impact ionization
+rate in narrow-gap semiconductors $\mathrm{InSb}$, $\mathrm{InAs}$,
+$\mathrm{GaSb}$ and $\mathrm{In}_{0.53}\mathrm{Ga}_{0.47}\mathrm{As}$ is
+isotropic while in middle-gap $\mathrm{InP}$, $\mathrm{GaAs}$ and
+$\mathrm{CdTe}$ both terms are comparable. We propose simple and justified
+analytic generalization of Keldysh formula for the impact ionization rate valid
+for direct-gap semiconductors with $E_g$ up to $\mathrm{1.5}~\mathrm{eV}$,
+which is suitable for incorporation into modelling software.",2112.05021v2
+2021-12-11,Domain dependent Fermi arcs observed in a striped phase dichalcogenide,"Angle-resolved photoemission spectromicroscopy on IrTe2 reveals evolution of
+mesoscopic striped domains across its first order phase transition at about 280
+K. The striped texture of the domains is characterized by a herringbone
+arrangement of the electronic anisotropy axes. Under further cooling down to 47
+K, the striped domains evolve into trijunction domains with the electronic
+anisotropy in three directions. Each domain harbors quasi one-dimensional
+surface bands forming Fermi arcs with peculiar spin polarization. The Fermi arc
+corresponds to an edge state of the two-dimensional bulk electronic states
+truncated at the surface, indicating an interesting interplay between the
+symmetry breaking and the surface electronic states.",2112.05930v1
+2021-12-13,Induction of Large Magnetic Anisotropy Energy and Formation of Multiple Dirac States in SrIrO$_3$ Films: Role of correlation and spin-orbit coupling,"The 5$d$ transition metal oxides, in particular iridates, host novel
+electronic and magnetic phases due to the interplay between onsite Coulomb
+repulsion ($U$) and spin-orbit coupling (SOC). The reduced dimensionality
+brings another degree of freedom to increase the functionality of these
+systems. By taking the example of ultrathin films of SrIrO$_3$,theoretically,
+we demonstrate that confinement led localization can introduce large magnetic
+anisotropy energy (MAE) in the range 2-7 meV/Ir which is one to two orders
+higher than that of the traditional MAE compounds formed out of transition
+metals and their multilayers. Furthermore, in the weak correlation limit,
+tailored terminations can yield multiple Dirac states across a large energy
+window of 2 eV around the Fermi energy which is a rare phenomena in correlated
+oxides and upon experimental realization it will give rise to unique transport
+properties with excitation and doping.",2112.06813v2
+2021-12-16,Dynamics of water and ethanol in graphene oxide,"We utilized the momentum transfer(Q)-dependence of Quasi-Elastic Neutron
+Scattering (QENS) to reveal the dynamics of water and ethanol confined in
+Graphene Oxide (GO) powder or membranes at different temperatures and in
+different orientations. The dynamics was measured across different length and
+time scales using several spectrometers. We found reduced diffusivities (up to
+30\% in the case of water) and a depression of the transition temperatures.
+While water showed near Arrhenius behavior with an almost bulk-like activation
+barrier in a temperature range of 280-310 K, the diffusivity of ethanol showed
+little temperature dependence. For both water and ethanol, we found evidence
+for immobile and mobile fractions of the confined liquid. The mobile fraction
+exhibited jump diffusion, with a jump length consistent with the expected
+average spacing of hydroxide groups in the GO surfaces. From anisotropy
+measurements, we found weak anisotropy in diffusion, with the surprising result
+that diffusion was faster perpendicular to membrane than parallel to it.",2112.09235v1
+2021-12-19,Heisenberg spins on an anisotropic triangular lattice: PdCrO2 under uniaxial stress,"When Heisenberg spins interact antiferromagnetically on a triangular lattice
+and nearest-neighbor interactions dominate, the ground state is 120$^{\circ}$
+antiferromagnetism. In this work, we probe the response of this state to
+lifting the triangular symmetry, through investigation of the triangular
+antiferromagnet PdCrO$_2$ under uniaxial stress by neutron diffraction and
+resistivity measurements. The periodicity of the magnetic order is found to
+change rapidly with applied stress; the rate of change indicates that the
+magnetic anisotropy is roughly forty times the stress-induced bond length
+anisotropy. At low stress, the incommensuration period becomes extremely long,
+on the order of 1000 lattice spacings; no locking of the magnetism to
+commensurate periodicity is detected. Separately, the magnetic structure is
+found to undergo a first-order transition at a compressive stress of $\sim$0.4
+GPa, at which the interlayer ordering switches from a double- to a single-q
+structure.",2112.10215v1
+2021-12-20,Anisotropies in Cosmological 21 cm Background by Oscillons/I-balls of Ultra-light Axion-like Particle,"Ultra-light axion-like particle (ULAP) with mass $m \sim 10^{-22}
+~\mathrm{eV}$ has recently been attracting attention as a possible solution to
+the small-scale crisis. ULAP forms quasi-stable objects called
+oscillons/I-balls, which can survive up to a redshift $z \sim 10$ and affect
+the structure formation on a scale $\sim \mathcal{O}(0.1)~\mathrm{Mpc}$ by
+amplifying the density fluctuations. We study the effect of oscillons on 21~cm
+anisotropies caused by neutral hydrogen in minihalos. It is found that this
+effect can be observed in a wide mass range by future observations such as
+Square Kilometer Array~(SKA) if the fraction of ULAP to the total dark matter
+density is $\mathcal{O}(0.01 \text{--} 0.1)$.",2112.10464v1
+2021-12-22,Effects of anisotropy on the transition to absolute instability in a porous medium heated from below,"The emerging instability of a forced throughflow in a fluid saturated
+horizontal porous duct of rectangular cross section is investigated. The duct
+is heated from below by assuming the horizontal boundaries to be at different
+temperatures. Both the horizontal and the vertical boundaries are impermeable
+and the basic flow is parallel to such boundaries. The porous medium is
+anisotropic with different permeabilities in the vertical and horizontal
+directions. The effect of the anisotropy on the onset of the buoyancy driven
+modal instability and absolute instability is analysed. The parametric
+conditions leading to the instability of the basic flow are determined by
+employing an analytical dispersion relation. The different permeabilities in
+the vertical and horizontal directions come out to play opposite roles in the
+onset of modal instability and in the transition to absolute instability. It is
+shown that an increasing vertical permeability has a destabilising effect,
+while an increasing horizontal permeability has a stabilising effect.",2112.11733v2
+2021-12-22,Anisotropic cosmic-ray diffusion in isotropic Kolmogorov turbulence,"Understanding the time scales for diffusive processes and their degree of
+anisotropy is essential for modelling cosmic-ray transport in turbulent
+magnetic fields. We show that the diffusion time scales are isotropic over a
+large range of energy and turbulence levels, notwithstanding the high degree of
+anisotropy exhibited by the components of the diffusion tensor for cases with
+an ordered magnetic field component. The predictive power of the classical
+scattering relation as a description for the relation between the parallel and
+perpendicular diffusion coefficients is discussed and compared to numerical
+simulations. Very good agreement for a large parameter space is found,
+transforming classical scattering relation predictions into a computational
+prescription for the perpendicular component. We discuss and compare these
+findings and in particular the time scales to become diffusive with the time
+scales that particles reside in astronomical environments, the so-called escape
+time scales. The results show that, especially at high energies, the escape
+times obtained from diffusion coefficients may exceed the time scales required
+for diffusion. In these cases, the escape time cannot be determined by the
+diffusion coefficients.",2112.11827v1
+2021-12-23,Electric-field-induced parametric excitation of exchange magnons in a CoFeB/MgO junction,"Electric-field controlled magnetization dynamics is an important integrant in
+low power spintronic devices. In this letter, we demonstrate electric-field
+induced parametric excitation for CoFeB/MgO junctions by using interfacial
+in-plane magnetic anisotropy. When the in-plane magnetic anisotropy and the
+external magnetic field are parallel to each other, magnons are efficiently
+excited by using electric-field induced parametric excitation. Its wavelength
+and wavenumber are tuned by changing input power and frequency of the applied
+voltage. A generalized phenomenological model is developed to explain the
+underlying role of the electric-field torque. Electrical excitation with no
+Joule heating offers a good opportunity for developing magnonic devices and
+exploring various nonlinear dynamics in magnetic systems.",2112.12308v2
+2021-12-28,Superfluid Spin Transistor,"We propose to use the Hall response of topological defects, such as merons
+and antimerons, to spin currents in 2D magnetic insulator with in-plane
+anisotropy for identification of the Berezinskii-Kosterlitz-Thouless (BKT)
+transition in a transistor-like geometry. Our numerical results relying on a
+combination of Monte Carlo and spin dynamics simulations show transition from
+spin superfluidity to conventional spin transport, accompanied by the universal
+jump of the spin stiffness and exponential growth of the transverse vorticity
+current. We propose a superfluid spin transistor in which the spin and
+vorticity currents are modulated by tuning the in-plane magnet across BKT
+transition, e.g., by changing the exchange interaction, magnetic anisotropy, or
+temperature.",2112.14241v2
+2022-01-07,Spatial data modeling by means of Gibbs Markov random fields based on a generalized planar rotator model,"We introduce a Gibbs Markov random field for spatial data on Cartesian grids
+which is based on the generalized planar rotator (GPR) model. The GPR model
+generalizes the recently proposed modified planar rotator (MPR) model by
+including in the Hamiltonian additional terms that better capture realistic
+features of spatial data, such as smoothness, non-Gaussianity, and geometric
+anisotropy. In particular, the GPR model includes up to infinite number of
+higher-order harmonics with exponentially vanishing interaction strength,
+directional dependence of the bilinear interaction term between nearest grid
+neighbors, longer-distance neighbor interactions, and two types of an external
+bias field. Hence, in contrast with the single-parameter MPR model, the GPR
+model features five additional parameters: the number $n$ of higher-order terms
+and the parameter $\alpha$ controlling their decay rate, the exchange
+anisotropy parameter $J^{nn}$, the further-neighbor interaction coupling
+$J^{fn}$, and the external field (bias) parameters $K$ (or $K'$). We present
+numerical tests on various synthetic data which demonstrate the effects of the
+respective terms on the model's prediction performance and we discuss these
+results in connection with the data properties.",2201.02537v1
+2022-01-11,Graphene Lattices with Embedded Transition-Metal Atoms and Tunable Magnetic Anisotropy Energy: Implications for Spintronic Devices,"Doping of the graphene lattice with transition metal atoms resulting in high
+magnetic anisotropy energy (MAE) is an important goal of materials research
+owing to its potential application in spintronics. In this article, by using
+spin-polarized density functional theory including spin-orbit coupling, we
+examined magnetic properties of graphene with vacancy defects, both bare and
+nitrogen-decorated, and doped by Cr, Mn and Fe transition metal single atom
+(TM-SA) and two different TM atoms simultaneously. [...] The computational
+findings are supplemented by an atomic-resolution characterization of an
+incidental Mn impurity bonded to four carbon atoms, whose localized spin
+matches expectations as measured using core-level electron energy-loss
+spectroscopy. Conducting TM-doped graphene with robust magnetic features offers
+prospects for the design of graphene-based spintronic devices.",2201.03867v1
+2022-01-17,Scanning nitrogen-vacancy center magnetometry in large in-plane magnetic fields,"Scanning magnetometry with nitrogen-vacancy (NV) centers in diamond has
+emerged as a powerful microscopy for studying weak stray field patterns with
+nanometer resolution. Due to the internal crystal anisotropy of the spin
+defect, however, external bias fields -- critical for the study of magnetic
+materials -- must be applied along specific spatial directions. In particular,
+the most common diamond probes made from {100}-cut diamond only support fields
+at an angle of $\theta = 55^\circ$ from the surface normal. In this paper, we
+report fabrication of scanning diamond probes from {110}-cut diamond where the
+spin anisotropy axis lies in the scan plane ($\theta=90^\circ$). We show that
+these probes retain their sensitivity in large in-plane fields and demonstrate
+scanning magnetometry of the domain pattern of Co-NiO films in applied fields
+up to 40 mT. Our work extends scanning NV magnetometry to the important class
+of materials that require large in-plane fields.",2201.06450v2
+2022-01-18,Timing-residual power spectrum of a polarized stochastic gravitational-wave background in pulsar-timing-array observation,"We study the observation of stochastic gravitational-wave background (SGWB)
+made by pulsar-timing arrays in the spherical harmonic space. Instead of using
+the Shapiro time delay, we keep the Sachs-Wolfe line-of-sight integral for the
+timing residual of an observed pulsar. We derive the power spectrum of the
+timing residual, from which the overlap reduction functions and the bipolar
+spherical harmonics coefficients are constructed for the SGWB intensity and
+polarization anisotropies. We have reproduced the previous results, noting that
+we have developed a fast algorithm for computing accurate overlap reduction
+functions and the bipolar spherical harmonics coefficients for the
+linear-polarization anisotropy are worked out for the first time. Our
+harmonic-space method is useful for future pulsar-timing-array observation on a
+few thousand pulsars and provides optimal estimators for testing the
+statistical isotropy of the SGWB.",2201.06767v1
+2022-01-19,Nodal multigap superconductivity in the anisotropic iron-based compound RbCa2Fe4As4F2,"The 12442 compounds are a recently discovered family of iron-based
+superconductors, that share several features with the cuprates due to their
+strongly anisotropic structure, but are so far poorly understood. Here, we
+report on the gap structure and anisotropy of RbCa2(Fe1-xNix)4As4F2 single
+crystals, investigated by a combination of directional point-contact
+Andreev-reflection spectroscopy and coplanar waveguide resonator measurements.
+Two gaps were identified, with clear signatures of d-wave-like nodal structures
+which persist upon Ni doping, well described by a two-band d-d state with
+symmetry-imposed nodes. A large London penetration depth anisotropy was
+revealed, weakly dependent on temperature and fully compatible with the d-d
+model.",2201.07593v1
+2022-01-21,Cavity Ferromagnetic Resonance Study of Acoustic and Optic excitations in Ru/Cr/Co and Ru/Co multilayers,"Two series of [Ru10/Cox)]12 and [Ru6/Cr3/Cox)]12 x=16-60 easy-plane
+anisotropy multilayers (all thicknesses in {\AA}), prepared by sputter
+deposition, are studied by cavity FMR. The acoustic modes are excited by
+setting the RF field perpendicular to the saturating in-plane field. Their
+resonance fields are in good agreement with the values predicted for acoustic
+modes by macrospin models, using the interlayer RKKY exchange and anisotropy
+fields derived by the magnetic measurements. The resonance fields of the modes
+excited by setting the RF field parallel to the saturating field, are lower
+than those expected for optical modes. This and could attributed to the
+existence of hybridized mixed modes, according to results of micromagnetic
+simulations which also show that the mode mixing is related to the
+inhomogeneous magnetization profile along the multilayer thickness.",2201.08630v1
+2022-01-26,Anisotropic compact star with a linear pressure-density relationship,"We present a model of compact astrophysical object under General Theory of
+Relativity using the anisotropic extension of Tolman IV solution. The
+anisotropy function, derived from the model, remains well behaved throughout
+the interior of the star. The model satisfies several necessary conditions for
+a physically realistic compact star. Physical viability of the model is
+verified specifically by plugging in the estimated parameter values of the Low
+Mass X-ray Binary (LMXB) candidate 4U 1608 - 52. Our stability analysis of this
+star, by using various criteria for stability, provide satisfactory results. In
+connection to anisotropy, we compute the Tidal Love Number (TLN) for the
+compact stellar model and compare the calculated values with existing
+literature.",2201.10772v1
+2022-02-04,Influence of the triangular Mn-O breathing mode on the magnetic ordering in multiferroic hexagonal manganites,"We use a combination of symmetry analysis, phenomenological modelling and
+first-principles density functional theory to explore the interplay between the
+magnetic ground state and the detailed atomic structure in the hexagonal
+rare-earth manganites. We find that the magnetic ordering is sensitive to a
+breathing mode distortion of the Mn and O ions in the $ab$ plane, which is
+described by the K\textsubscript{1} mode of the high-symmetry structure. Our
+density functional calculations of the magnetic interactions indicate that this
+mode particularly affects the single-ion anisotropy and the inter-planar
+symmetric exchanges. By extracting the parameters of a magnetic model
+Hamiltonian from our first-principles results, we develop a phase diagram to
+describe the magnetic structure as a function of the anisotropy and exchange
+interactions. This in turn allows us to explain the dependence of the magnetic
+ground state on the identity of the rare-earth ion and on the
+K\textsubscript{1} mode.",2202.02304v1
+2022-02-07,DFT insights into the new Hf-based chalcogenide MAX phase Hf2SeC,"The physical characteristics of the novel chalcogenide MAX phase Hf2SeC have
+been investigated using the DFT method. The obtained lattice constant and
+elastic constants (Cij) are compared with previous results to check the
+consistency of our setting parameters during calculations Moreover, the elastic
+properties such as elastic constants, moduli, anisotropy, and hardness are also
+compared with preexisting MAX phases of its kind. The checking of mechanical
+stability has been done based on Cij in accordance with the previously stated
+stability criteria. The reason for the higher hardness of Hf2SeC compared to
+Hf2SC is explained using the density of states (DOS). The brittleness character
+of Hf2SeC has been revealed using the Pugh ratio, Poisson ratio, and Cauchy
+pressure. The electronic properties (band structure and charge density mapping)
+of Hf2SeC are studied to disclose the metallic nature as well as bonding nature
+within the titled chalcogenide. The anisotropy in both electronic conductivity
+and mechanical properties is investigated. The temperature and pressure
+dependence of volume, Gr\""uneisen parameter, Debye temperature, thermal
+expansion coefficient (TEC), and specific heat at constant volume (Cv) are
+explored. In addition, minimum thermal conductivity (Kmin) and melting point
+(Tm) are studied to explore its suitability for high-temperature applications.",2202.03370v1
+2022-02-07,Optically induced anisotropy in time-resolved scattering: Imaging molecular scale structure and dynamics in disordered media with experiment and theory,"Time-resolved scattering experiments enable imaging of materials at the
+molecular scale with femtosecond time resolution. However, in disordered media
+they provide access to just one radial dimension thus limiting the study of
+orientational structure and dynamics. Here we introduce a rigorous and
+practical theoretical framework for predicting and interpreting experiments
+combining optically induced anisotropy and time-resolved scattering. Using
+impulsive nuclear Raman and ultrafast X-ray scattering experiments of
+chloroform and simulations, we demonstrate that this framework can accurately
+predict and elucidate both the spatial and temporal features of these
+experiments.",2202.03562v1
+2022-02-05,Stochastic aspects of crack deflection and crack path prediction in short fiber reinforced polymer matrix composites,"Owing to the production process, short fiber reinforced composites exhibit a
+pronounced anisotropy of both elastic properties and crack growth resistance.
+In particular the latter issue has a major impact on crack deflection and
+inevitably has to be taken into account for the sake of an accurate prediction
+of crack paths. The perpendicular axes of transverse isotropy are associated
+with the fiber orientations, whereupon a crack in transverse direction
+encounters the largest fracture toughness. While the local mean fiber
+orientations in polymer matrix composites are determined by the injection
+molding process, their statistical fluctuations can approximately be described
+in terms of Gaussian random field models. Furthermore, statistical variations
+of the volume fraction of fibers and the fiber-matrix adhesion give rise to
+stochasticity of the local ratio of fracture toughness anisotropy. Influencing
+factors of prediction regions of crack paths obtained from finite element
+simulations with an adapted J-integral deflection criterion are investigated,
+just as stochastic aspects of bifurcation phenomena of crack deflection
+observed under mode-I loading.",2202.06748v1
+2022-02-15,Sharp phase-field modeling of isotropic solidification with a super efficient spatial resolution,"The numerical resolution efficiency of phase-field models is limited by grid
+friction, grid anisotropy and pinning. The 1D sharp phase-field model
+eliminates grid friction and pinning by a global restoration of Translational
+Invariance (TI) in the discretized phase-field equation (Phys. Rev. Lett. 121,
+025501, 2018). In 3D global TI restricts the beneficial modeling properties to
+a finite number of fixed interface orientations. We propose an accurate scheme
+to restore TI locally in the local interface normal direction. At
+one-grid-point interface resolutions, the new model captures the formation of
+isotropic seaweed structures without spurious dendritic selection by grid
+anisotropy.",2202.07433v3
+2022-02-15,Spin orbital reorientation transitions induced by magnetic field,"Here we report on a new effect similar to the spin reorientation transition
+(SRT) that takes place at two magnetic fields of $B_{SORT1}$ and $B_{SORT2}$.
+The effect is observed in the magnetization curves of small Mn$^{3+}$ magnetic
+clusters in the wurtzite GaN (being in a paramagnetic state) calculated using
+crystal field model approach. The obtained results suggest that the computed
+magnetic anisotropy (MA) reverses its sign on increasing $B$ across $B_{SORT}$.
+Detailed analysis show however that MA is unchanged for high magnetic fields.
+We show that the observed effect arises from the interplay of the crystalline
+environment and the spin-orbit coupling $\lambda \hat{\textbf{S}}
+\hat{\textbf{L}}$, therefore we name it spin orbital reorientation transition
+(SORT). The value of $B_{SORT1}$ depends on the crystal field model parameters
+and the number of ions $N$ in a given cluster, whereas $B_{SORT2}$ is
+controlled mostly by the magnitude of the spin-orbit coupling $\lambda$. The
+explanation of SORT is given in terms of the spin $M_S$ and orbital momentum
+$M_L$ contributions to the total magnetization $M = M_S + M_L$. The similar
+effect should also be present in other materials with not completely quenched
+(non zero) orbital angular momentum $L$, a uniaxial magnetic anisotropy and the
+positive value of $\lambda$.",2202.07443v1
+2022-03-01,Using the Energy probability distribution zeros to obtain the critical properties of the two-dimensional anisotropic Heisenberg model,"In this paper we present a Monte Carlo study of the critical behavior of the
+easy axis anisotropic Heisenberg spin model in two dimensions. Based on the
+partial knowledge of the zeros of the energy probability distribution we
+determine with good precision the phase diagram of the model obtaining the
+critical temperature and exponents for several values of the anisotropy. Our
+results indicate that the model is in the Ising universality class for any
+anisotropy.",2203.00419v2
+2022-03-06,Entropy production in longitudinally expanding Yang-Mills field with use of Husimi function$-$semiclassical approximation,"We investigate the possible thermalization process of the highly occupied and
+weakly coupled Yang-Mills fields expanding along the beam axis through an
+evaluation of the entropy, particle number, and pressure anisotropy. The time
+evolution of the system is calculated by solving the equation of motion for the
+Wigner function in the semiclassical approximation with initial conditions
+mimicking the glasma. For the evaluation of the entropy, we adopt the
+Husimi-Wehrl (HW) entropy, which is obtained by using the Husimi function, a
+positive semidefinite quantum distribution function given by smearing the
+Wigner function. By numerical calculations at $g=0.1$ and $0.2$, the entropy
+production is found to occur together with the particle creation in two
+distinct stages: In the first stage, the particle number and the entropy at low
+longitudinal momenta grow rapidly. In the second stage, the particle number and
+the entropy of higher longitudinal momentum modes show slower increase. The
+pressure anisotropy remains in our simulation and implies that the system is
+still out-of-equilibrium.",2203.02859v3
+2022-03-07,"Influence of Charge on Extended Decoupled Anisotropic Solutions in $f(\mathcal{R},\mathcal{T},\mathcal{R}_{λξ}\mathcal{T}^{λξ})$ Gravity","In this paper, we consider static self-gravitating spherical spacetime and
+determine various anisotropic solutions through the extended gravitational
+decoupling technique in
+$f(\mathcal{R},\mathcal{T},\mathcal{R}_{\lambda\xi}\mathcal{T}^{\lambda\xi})$
+gravity to analyze the influence of electromagnetic field on them. We construct
+two different sets of modified field equations by employing the transformations
+on both radial as well as temporal metric potentials. The first set symbolizes
+the isotropic fluid distribution, thus we take Krori-Barua solution to deal
+with it. The indefinite second sector comprises the influence of anisotropy. In
+this regard, we apply some constraints to determine unknowns. Further, we
+observe the impact of charge as well as decoupling parameter $\zeta$ on the
+developed physical variables (such as energy density,~radial and tangential
+pressures) and anisotropy. We also analyze other physical features of the
+compact geometry like mass, compactness and redshift along with the energy
+conditions. Eventually, we find that our both solutions show less stable
+behavior for higher values of charge near the boundary in this gravity.",2203.03268v1
+2022-03-11,Magnetic anisotropy energies and metal-insulator transitions in monolayers of $α$-RuCl$_3$ and OsCl$_3$ on graphene,"Transition metal thriclorides, with $4d$ or $5d$ electrons, are materials at
+the forefront of recent studies about the interplay of spin-orbit coupling and
+strong Coulomb interactions. Within our first-principles calculations
+(DFT+$U$+SOC) we study the effects of graphene on the electronic and magnetic
+properties of the monolayers of $\alpha$-RuCl$_3$ and OsCl$_3$. Despite the
+spatially inhomogeneous $n$-type doping induced by graphene, we show that the
+occupancy of the upper Hubbard bands of MLs of \rucl and OsCl$_3$ can be tuned
+through external electric fields, and allows the control of (i) metal-insulator
+transitions, and (ii) the magnetic easy-axis and anisotropy energies. Our
+findings point towards the tunning of electronic and magnetic properties of
+transition metal thriclorides monolayers by using graphene and external
+electronic fields.",2203.06052v1
+2022-03-21,Constraints of anisotropy on warm power-law inflation in light of Planck results,"In this article, we examine the effects of anisotropy on a model of canonical
+warm inflation with the power-law potential. The results of this model are
+compared to Planck satellite observational data. Using a conventional local
+scalar fi?eld in the Bianchi type I metric, the slow-roll conditions and the
+suitable regions, where the free parameters of the model show a good agreement
+with Planck results, are investigated in detail. Following the usual
+calculations for warm inflationary approaches, the early universe in two
+different dissipative regimes, namely the weak dissipative and the strong
+dissipative ones, is investigated. In this regard, the slow-roll parameters and
+their observational indices in both regimes are obtained and finally, it is
+shown that this model is in good agreement with observatio",2203.11165v1
+2022-03-23,Holographic model for light quarks in anisotropic hot dense QGP with external magnetic field,"We present a five-dimensional twice anisotropic holographic model supported
+by Einstein-dilaton-three-Maxwell action describing light quarks. The first of
+the Maxwell fields provides finite chemical potential. The second Maxwell field
+serves for anisotropy, characterizing spatial anisotropy of the QGP produced in
+heavy-ion collisions (HIC). The third Maxwell field is related to a magnetic
+field that appears in HIC. The dependence of the 5-dim black hole solution and
+confinement/deconfinement phase diagram on this magnetic field is considered.
+The effect of the inverse magnetic catalyses for light quarks phase diagram is
+obtained. Positions of critical end points are found. We also study the
+behavior of the conductivity for light quarks in both isotropic and anisotropic
+cases and show that behaviour of the conductivity near critical points
+essentially depend on quark masses, meanwhile at high temperature they are
+similar.",2203.12539v2
+2022-03-28,Quantum Yu-Shiba-Rusinov dimers,"Magnetic adatoms on a superconducting substrate undergo a quantum phase
+transition as their exchange coupling to the conduction electrons increases.
+For quantum spins, this transition is accompanied by screening of the adatom
+spin. Here, we explore the consequences of this screening for the phase
+diagrams and subgap excitation spectra of dimers of magnetic adatoms coupled by
+hybridization of their Yu-Shiba-Rusinov states and spin-spin interactions. We
+specifically account for higher spins, single-ion anisotropy,
+Ruderman-Kittel-Kasuya-Yosida coupling, and Dzyaloshinsky-Moriya interactions
+relevant in transition-metal and rare-earth systems. Our flexible approach
+based on a zero-bandwidth approximation provides detailed physical insight and
+is in excellent qualitative agreement with available numerical-renormalization
+group calculations on monomers and dimers. Remarkably, we find that even in the
+limit of large impurity spins or strong single-ion anisotropy, the phase
+diagrams for dimers of quantum spins remain qualitatively distinct from phase
+diagrams based on classical spins, highlighting the need for a theory of
+quantum Yu-Shiba-Rusinov dimers.",2203.15011v1
+2022-04-04,"Large-scale asymmetry in galaxy spin directions -- analysis of galaxies with spectra in DES, SDSS, and DESI Legacy Survey","Multiple previous studies using several different probes have shown
+considerable evidence for the existence of cosmological-scale anisotropy and a
+Hubble-scale axis. One of the probes that show such evidence is the
+distribution of the directions toward which galaxies spin. The advantage of the
+analysis of the distribution of galaxy spin directions compared to the CMB
+anisotropy is that the ratio of galaxy spin directions is a relative
+measurement, and therefore less sensitive to background contamination such as
+Milky Way obstruction. Another advantage is that many spiral galaxies have
+spectra, and therefore allow to analyze the location of such axis relative to
+Earth. This paper shows an analysis of the distribution of the spin directions
+of over 90K galaxies with spectra. That analysis is also compared to previous
+analyses using the Earth-based SDSS, Pan-STARRS, and DESI Legacy Survey, as
+well as space-based data collected by HST. The results show very good agreement
+between the distribution patterns observed with the different telescopes. The
+dipole or quadrupole axes formed by the spin directions of the galaxies with
+spectra do not necessarily go directly through Earth.",2204.01192v1
+2022-04-04,"Inter- to Intra-Layer Resistivity Anisotropy of NdFeAs(O,H) with Various Hydrogen Concentrations","With molecular beam epitaxy and topotactic chemical reaction, we prepared
+NdFeAs(O,H) epitaxial thin films with various hydrogen concentrations on
+5{\deg} vicinal cut MgO substrates. By measuring the resistivities along the
+longitudinal and transversal directions, the ab plane and the c axis
+resistivities (\{rho}_ab and \{rho}_c) were obtained. The resistivity
+anisotropy {\gamma}_\{rho}=\{rho}_c \ \{rho}_ab of NdFeAs(O,H) with various
+hydrogen concentrations was compared with that of NdFeAs(O,F). At the H
+concentrations which led to superconducting transition temperatures Tc over 40
+K, {\gamma}_\r{ho} recorded ~100-150 at 50 K. On the other hand, a low
+{\gamma}_\{rho} value of 9 was observed with the mostly doped sample. The
+exponent \{beta} of the ab plane resistivity obtained by fitting a power law
+expression \{rho}_{ab}(T)=\{rho}_0+AT^\{beta} to the data was close to unity
+down to low temperature in the vicinity where the second antiferromagnetic
+phase locates, which may be related to the quantum critical point discussed at
+the over-doped side of the phase diagram.",2204.01554v1
+2022-04-09,The skyrmion bags in an anisotropy gradient,"Skyrmion bags as spin textures with arbitrary topological charge are expected
+to be the carriers in racetrack memory. Here, we theoretically and numerically
+investigated the dynamics of skyrmion bags in an anisotropy gradient. It is
+found that, without the boundary potential, the dynamics of skyrmion bags are
+dependent on the spin textures, and the velocity of skyrmionium with $Q = 0$ is
+faster than other skyrmion bags. However, when the skyrmion bags move along the
+boundary, the velocities of all skyrmion bags with different $Q$ are same. This
+can be attributed to the same value of $u/\eta_{xx}$, where the $u$ and
+$\eta_{xx}$ are the terms related to the magnetization distribution of skyrmion
+bag. In addition, we theoretically derived the dynamics of skyrmion bags in the
+two cases using the Thiele approach and discussed the scope of Thiele equation.
+Within a certain range, the simulation results are in good agreement with the
+analytically calculated results. Our findings provide an alternative way to
+manipulate the racetrack memory based on the skyrmion bags.",2204.04439v2
+2022-04-18,Cosmic microwave background spectral distortions from Rayleigh scattering at second order,"Cosmic microwave background (CMB) spectral distortion from Rayleigh
+scattering is calculated for the first time in rigorous second-order
+cosmological perturbation theory. The new spectral distortion is sensitive to
+acoustic dissipation at $10^{-2}<k{\rm Mpc}/h<1$, which slightly extends the
+scale constrained by the CMB anisotropies. The spectral shape is different from
+either temperature perturbations or any other traditional spectral distortions
+from Compton scattering, such as $y$ and $\mu$. The new spectral distortion is
+not formed in the late Universe, unlike the thermal Sunyaev-Zel'dovich effect
+degenerated with the primordial $y$ distortions since photons must be hot for
+Rayleigh scattering. Therefore, ideal measurements can distinguish the signal
+from the other effects and extract new information during recombination.
+Assuming cosmological parameters consistent with the recent CMB anisotropy
+measurements, we find the new spectral distortion is $6.5\times 10^{-3}$Jy/str,
+which is one order of magnitude smaller than the currently proposed target
+sensitivity range of voyage 2050.",2204.08177v1
+2022-04-19,Role of shape anisotropy on thermal gradient-driven domain wall dynamics in magnetic nanowires,"We investigate the magnetic domain wall (DW) dynamics in uniaxial/biaxial
+nanowires under a thermal gradient (TG). The findings reveal that the DW
+propagates toward the hotter region in both nanowires. The main physics of such
+observations is the magnonic angular momentum transfer to the DW. The hard
+(shape) anisotropy exists in biaxial nanowire, which contributes an additional
+torque, hence DW speed is larger than that in uniaxial nanowire. With lower
+damping, the DW velocity is smaller and DW velocity increases with damping
+which is opposite to usual expectation. To explain this, it is predicted that
+there is a probability to form the standing spin-waves (which do not carry net
+energy/momentum) together with travelling spin-waves if the propagation length
+of thermally-generated spin-waves is larger than the nanowire length. For
+larger-damping, DW decreases with damping since the magnon propagation length
+decreases. Therefore, the above findings might be useful in realizing the
+spintronic (racetrack memory) devices.",2204.09101v2
+2022-04-21,Wurtzite quantum wires with strong spatial confinement: polarization anisotropies in single wire spectroscopy,"We report GaAs/AlGaAs nanowires in the one-dimensional (1D) quantum limit.
+The ultrathin wurtzite GaAs cores between 20-40\,nm induce large confinement
+energies of several tens of meV, allowing us to experimentally resolve up to
+four well separated subband excitations in microphotoluminescence spectroscopy.
+Our detailed experimental and theoretical polarization-resolved study reveals a
+strong diameter-dependent anisotropy of these transitions: We demonstrate that
+the polarization of the detected photoluminescence is governed by the symmetry
+of the wurtzite 1D quantum wire subbands on the one hand, but also by the
+dielectric mismatch of the wires with the surrounding material on the other
+hand. The latter effect leads to a strong attenuation of perpendicularly
+polarized light in thin dielectric wires, making the thickness of the AlGaAs
+shell an important factor in the observed polarization behavior. Including the
+dielectric mismatch to our k.p-based simulated polarization-resolved spectra of
+purely wurtzite GaAs quantum wires, we find an excellent agreement between
+experiment and theory.",2204.09991v1
+2022-04-25,Ab-initio study of magneto-ionic mechanisms in ferromagnet/oxide multilayers,"The application of gate voltages in heavy metal/ferromagnet/Oxide multilayer
+stacks has been identified as one possible candidate to manipulate their
+anisotropy at will. However, this method has proven to show a wide variety of
+behaviours in terms of reversibility, depending on the nature of the
+metal/oxide interface and its degree of oxidation. In order to shed light on
+the microscopic mechanism governing the complex magneto-ionic behaviour in
+$\text{Ta/CoFeB/}\text{HfO}_2$, we perform ab-initio simulations on various
+setups comprising $\text{Fe/O, Fe/HfO}_2$ interfaces with different oxygen atom
+interfacial geometries. After the determination of the more stable interfacial
+configurations, we calculate the magnetic anisotropy energy on the different
+unit cell configurations and formulate a possible mechanism that well describes
+the recent experimental observations in $\text{Ta/CoFeB/}\text{HfO}_2$.",2204.11699v1
+2022-04-26,Cosmology from the kinetic polarized Sunyaev Zel'dovich effect,"The cosmic microwave background (CMB) photons that scatter off free electrons
+in the large-scale structure induce a linear polarization pattern proportional
+to the remote CMB temperature quadrupole observed in the electrons' rest frame.
+The associated blackbody polarization anisotropies are known as the polarized
+Sunyaev Zel'dovich (pSZ) effect. Relativistic corrections to the remote
+quadrupole field give rise to a non-blackbody polarization anisotropy
+proportional to the square of the transverse peculiar velocity field; this is
+the kinetic polarized Sunyaev Zel'dovich (kpSZ) effect. In this paper, we
+forecast the ability of future CMB and galaxy surveys to detect the kpSZ
+effect, finding that a statistically significant detection is within the reach
+of planned experiments. We further introduce a quadratic estimator for the
+square of the peculiar velocity field based on a galaxy survey and CMB
+polarization. Finally, we outline how the kpSZ effect is a probe of cosmic
+birefringence and primordial non-Gaussianity, forecasting the reach of future
+experiments.",2204.12503v2
+2022-05-02,Pre-hydrodynamic evolution and its impact on quark-gluon plasma signatures,"State-of-the-art hydrodynamic models of heavy-ion collisions have
+considerable theoretical model uncertainties in the description of the very
+early pre-hydrodynamic stage. We add a new computational module,
+K$_\mathrm{T}$Iso, that describes the pre-hydrodynamic evolution kinetically,
+based on the relativistic Boltzmann equation with collisions treated in the
+Isotropization Time Approximation. As a novelty, K$_\mathrm{T}$Iso allows for
+the inclusion and evolution of initial-state momentum anisotropies. To maintain
+computational efficiency K$_\mathrm{T}$Iso assumes strict longitudinal boost
+invariance and allows collisions to isotropize only the transverse momenta. We
+use it to explore the sensitivity of hadronic observables measured in
+relativistic heavy-ion collisions to initial-state momentum anisotropies and
+microscopic scattering during the pre-hydrodynamic stage.",2205.00964v2
+2022-05-02,Anisotropic cosmic optical background bound for decaying dark matter in light of the LORRI anomaly,"Recently anomalous flux in the cosmic optical background (COB) has been
+reported by the New Horizon observations. The COB flux is $16.37\pm 1.47\, \rm
+nW m^{-2} sr^{-1}$, at the LORRI pivot wavelength of $0.608\,\rm \mu m$, which
+is $\sim 4\sigma$ level above the expected flux from the Hubble Space Telescope
+(HST) galaxy count. It would be great if this were a hint for the eV scale dark
+matter decaying into photons. In this paper, we point out that such a decaying
+dark matter model predicts a substantial amount of anisotropy in the COB flux,
+which is accurately measured by the HST. The data of the HST excludes the decay
+rate of the dominant cold dark matter larger than $10^{-24}$-$10^{-23}\,{\rm
+s}^{-1}$ in the mass range of $5$-$20$eV. As a result, the decaying cold dark
+matter explaining the COB excess is strongly disfavored by the anisotropy
+bound. We discuss some loopholes: e.g. warm/hot dark matter or two-step decay
+of the dark matter, to explain the COB excess.",2205.01079v2
+2022-05-09,"Controlling magnetic exchange and anisotropy by non-magnetic ligand substitution in layered MPX3 (M = Ni, Mn; X = S, Se)","Recent discoveries in two-dimensional (2D) magnetism have intensified the
+investigation of van der Waals (vdW) magnetic materials and further improved
+our ability to tune their magnetic properties. Tunable magnetism has been
+widely studied in antiferromagnetic metal thiophosphates MPX3. Substitution of
+metal ions M has been adopted as an important technique to engineer the
+magnetism in MPX3. In this work, we have studied the previously unexplored
+chalcogen X substitutions in MPX3 (M = Mn/Ni; X = S/Se). We synthesized the
+single crystals of MnPS3-xSex (0 < x < 3) and NiPS3-xSex (0 < x < 1.3) and
+investigated the systematic evolution of the magnetism with varying x. Our
+study reveals the effective tuning of magnetic interactions and anisotropies in
+both MnPS3 and NiPS3 upon Se substitution. Such efficient engineering of the
+magnetism provides a suitable platform to understand the low-dimensional
+magnetism and develop future magnetic devices.",2205.04585v1
+2022-05-13,The spatial distribution of satellites in galaxy clusters,"The planar distributions of satellite galaxies around the Milky Way and
+Andromeda have been extensively studied as potential challenges to the standard
+cosmological model. Using the Sloan Digital Sky Survey and the Millennium
+simulation we extend such studies to the satellite galaxies of massive galaxy
+clusters. We find that both observations and simulations of galaxy clusters
+show an excess of anisotropic satellite distributions. On average, satellites
+in clusters have a higher degree of anisotropy than their counterparts in
+Milky-Way-mass hosts once we account for the difference in their radial
+distributions. The normal vector of the plane of satellites is strongly aligned
+with the host halo's minor axis, while the alignment with the large-scale
+structure is weak. At fixed cluster mass, the degree of anisotropy is higher at
+higher redshift. This reflects the highly anisotropic nature of satellites
+accretion points, a feature that is partly erased by the subsequent orbital
+evolution of the satellites. We also find that satellite galaxies are mostly
+accreted singly so group accretion is not the explanation for the high
+flattening of the planes of satellites.",2205.06767v1
+2022-05-16,Fat-Tailed Variational Inference with Anisotropic Tail Adaptive Flows,"While fat-tailed densities commonly arise as posterior and marginal
+distributions in robust models and scale mixtures, they present challenges when
+Gaussian-based variational inference fails to capture tail decay accurately. We
+first improve previous theory on tails of Lipschitz flows by quantifying how
+the tails affect the rate of tail decay and by expanding the theory to
+non-Lipschitz polynomial flows. Then, we develop an alternative theory for
+multivariate tail parameters which is sensitive to tail-anisotropy. In doing
+so, we unveil a fundamental problem which plagues many existing flow-based
+methods: they can only model tail-isotropic distributions (i.e., distributions
+having the same tail parameter in every direction). To mitigate this and enable
+modeling of tail-anisotropic targets, we propose anisotropic tail-adaptive
+flows (ATAF). Experimental results on both synthetic and real-world targets
+confirm that ATAF is competitive with prior work while also exhibiting
+appropriate tail-anisotropy.",2205.07918v1
+2022-05-16,Surface Bound States in the Continuum in Dyakonov Structures,"Surface bound states in the continuum (SBICs) have been found to occur in
+diverse settings, but so far always at the interface of non-homogeneous media,
+such as discrete lattices or periodic systems. Here we show that they can also
+exist at the interface of homogeneous media, resulting in unique SBICs.
+Specifically, we found that, contrary to general belief, leaky Dyakonov states
+exist at the interface between materials that exhibit opposite signs of
+anisotropy. In addition, properly breaking the anisotropy-symmetry leads to the
+formation of both guided states and also SBICs embedded within the continuum. A
+direct implication of our finding is the possibility to create SBICs and
+Dyakonov states in a whole new class of materials and metamaterials.",2205.07940v1
+2022-05-24,Understanding temperature-dependent SU($3$) spin dynamics in the $S=1$ antiferromagnet Ba$_2$FeSi$_2$O$_7$,"Quantum magnets admit more than one classical limit and $N$-level systems
+with strong single-ion anisotropy are expected to be described by a classical
+approximation based on SU($N$) coherent states. Here we test this hypothesis by
+modeling finite temperature inelastic neutron scattering (INS) data of the
+effective spin-one antiferromagnet \bfso{}. The measured dynamic structure
+factor is calculated with a generalized Landau-Lifshitz dynamics for SU($3$)
+spins. Unlike the traditional classical limit based on SU($2$) coherent states,
+the results obtained with classical SU($3$) spins are in good agreement with
+the measured temperature-dependent spectrum. The SU($3$) approach developed
+here provides a general framework to understand the broad class of materials
+comprising weakly coupled antiferromagnetic dimers, trimers, or tetramers, and
+magnets with strong single-ion anisotropy.",2205.11770v1
+2022-05-25,Superconducting diode effect due to magnetochiral anisotropy in topological insulator and Rashba nanowires,"The critical current of a superconductor can depend on the direction of
+current flow due to magnetochiral anisotropy when both inversion and
+time-reversal symmetry are broken, an effect known as the superconducting (SC)
+diode effect. Here, we consider one-dimensional (1D) systems in which
+superconductivity is induced via the proximity effect. In both topological
+insulator and Rashba nanowires, the SC diode effect due to a magnetic field
+applied along the spin-polarization axis and perpendicular to the nanowire
+provides a measure of inversion symmetry breaking in the presence of a
+superconductor. Furthermore, a strong dependence of the SC diode effect on an
+additional component of magnetic field applied parallel to the nanowire as well
+as on the position of the chemical potential can be used to detect that a
+device is in the region of parameter space where the phase transition to
+topological superconductivity is expected to arise.",2205.12939v1
+2022-05-28,Atomic-scale Deformation Process of Glasses Unveiled by Stress-induced Structural Anisotropy,"Experimentally resolving atomic-scale structural changes of a deformed glass
+remains challenging owing to the disordered nature of glass structure. Here, we
+show that the structural anisotropy emerges as a general hallmark for different
+types of glasses (metallic glasses, oxide glass, amorphous selenium, and
+polymer glass) after thermo-mechanical deformation, and it is highly correlates
+with local nonaffine atomic displacements detected by the high-energy X-ray
+diffraction technique. By analyzing the anisotropic pair density function, we
+unveil the atomic-level mechanism responsible for the plastic flow, which
+notably differs between metallic glasses and covalent glasses. The structural
+rearrangements in metallic glasses are mediated through cutting and formation
+of atomic bonds, which occurs in some localized inelastic regions embedded in
+elastic matrix, whereas that of covalent glasses is mediated through the
+rotation of atomic bonds or chains without bond length change, which occurs in
+a less localized manner.",2205.14367v1
+2022-05-31,Electrical measurement of the Spin Hall Effect isotropy in a ferromagnet,"The spin-dependent transport properties of paramagnetic metals are roughly
+invariant under rotation. By contrast, in ferromagnetic materials the
+magnetization breaks the rotational symmetry, and thus the spin Hall effect is
+expected to become anisotropic. Here, using a specific design of lateral spin
+valves, we measure electrically the spin Hall Effect anisotropy in NiCu and
+NiPd, both in their ferromagnetic and paramagnetic phases. We show that the
+appearance of the ferromagnetic order does not lead to a sizeable anisotropy of
+the spin charge interconversion in these materials.",2205.15651v2
+2022-06-01,Imprints of Anisotropy on the Power Spectrum in Matter Dominated Bouncing Universe as Background,"In this paper, we aim to investigate the effects of the anisotropy on the
+scale-invariant power spectrum considering the matter-dominated collapsing
+universe as background and look for the deviations from this scale invariance.
+Having set up this background, we consider a massless scalar field and work out
+the correlations, first by using the perturbative approach in which the
+anisotropic background is approximated with an effective isotropic metric
+represented by the metric of matter dominated collapsing universe, second by
+directly solving the field equation numerically, and then obtain the power
+spectrum for the range of modes which are of cosmological interest. Using both
+techniques, we get an upper bound on the deviation in the power spectrum from
+the scale invariance. We also work out the power spectrum for much smaller
+modes and look at whether it is possible to explain the observed anomalies in
+CMB via the matter bounce scenario.",2206.00656v2
+2022-06-02,Hybrid iterative ensemble smoother for history matching of hierarchical models,"The choice of the prior model can have a large impact on the ability to
+assimilate data. In standard applications of ensemble-based data assimilation,
+all realizations in the initial ensemble are generated from the same covariance
+matrix with the implicit assumption that this covariance is appropriate for the
+problem. In a hierarchical approach, the parameters of the covariance function,
+for example the variance, the orientation of the anisotropy and the ranges in
+two principal directions, may all be uncertain. Thus, the hierarchical approach
+is much more robust against model misspecification. In this paper, three
+approaches to sampling from the posterior for hierarchical parameterizations
+are discussed: an optimization-based sampling approach (RML), an iterative
+ensemble smoother (IES), and a novel hybrid of the previous two approaches
+(hybrid IES). The three approximate sampling methods are applied to a
+linear-Gaussian inverse problem for which it is possible to compare results
+with an exact ""marginal-then-conditional"" approach. Additionally, the IES and
+the hybrid IES methods are tested on a two-dimensional flow problem with
+uncertain anisotropy in the prior covariance. The standard IES method is shown
+to perform poorly in the flow examples because of the poor representation of
+the local sensitivity matrix by the ensemble-based method. The hybrid method,
+however, samples well even with a relatively small ensemble size.",2206.01116v1
+2022-06-12,Electronic and magnetic properties of intermetallic Kagome magnets $R$V$_6$Sn$_6$ ($R$ = Tb - Tm),"We present a systematic study of the structure, electronic, and magnetic
+properties of a new branch of intermetalllic compounds, $R$V$_6$Sn$_6$ ($R$ =
+Tb - Tm) by using X-ray diffraction, magnetic susceptibility, magnetization,
+electrical transport, and heat-capacity measurements. These compounds feature a
+combination of a non-magnetic vanadium kagome sublattice and a magnetic
+rare-earth triangular sublattice that supports various spin anisotropies based
+on different $R$ ions. We find magnetic orders for the $R$ = Tb, Dy, and Ho
+compounds at 4.4, 3, 2.5 K, respectively, while no ordering is detected down to
+0.4 K for the $R$ = Er and Tm compounds with easy-plane anisotropies.
+Electronically, we found no superconductivity or charge ordering transition
+down to 0.4 K for any member of this family, while all compounds exhibit
+multi-band transport properties that originate from the band topology of the
+vanadium kagome sublattice.",2206.05653v1
+2022-06-15,Giant Rashba electrical control of magnetism in band models,"It is of considerable technological importance to achieve an electrical
+control of magnetism of sufficient magnitude. To overcome the in-plane shape
+anisotropy, needed is the electrical control of a perpendicular magnetic
+anisotropy (PMA). It is known, within a free electron model, the Rashba
+spin-orbit coupling provides such a control. Surprisingly, this same Rashba PMA
+is enhanced by two to three orders of magnitude when a periodic potential is
+added. Usually spin Berry phase physics reflects time dependent magnetic
+fields. Here it is shown, within a time independent model, such physics arises
+because the Rashba effective magnetic field has texture within the unit cell.
+Predicted are electrical controllable band-structure gaps, linear in the
+applied electric field $E$, that can result in a truly giant linear PMA. Also
+possible is a Peierls mechanism, in which the magnetisation tilts from the
+vertical, shifting these gaps to the Fermi level. As a consequence there are
+low dissipation electric field driven dynamics, an alternative to the more
+dissipative spin torque transfer (STT) effect. The theory requires the
+introduction of an intrinsic spin Berry connection $\vec A_s$, an effective
+vector potential, and is incompatible with current density functional theories
+(DFT).",2206.07399v1
+2022-06-30,Strain engineering of the magnetic anisotropy and magnetic moment in NdFeO3 epitaxial thin films,"Strain engineering is a powerful mean for tuning the various functionalities
+of ABO3 perovskite oxide thin films. Rare-earth orthoferrite RFeO3 materials
+such as NdFeO3 (NFO) are of prime interest because of their intriguing magnetic
+properties as well as their technological potential applications especially as
+thin films. Here, using a large set of complementary and advanced techniques,
+we show that NFO epitaxial thin films, successfully grown by pulsed laser
+deposition on (001)-SrTiO3, show a strong magnetic anisotropy below a critical
+thickness tc of 54 nm, associated with the occurrence of structural
+modifications related to symmetry and domain pattern changes. By varying the
+tensile misfit strain through the decrease of film thickness below tc, the
+amplitudes of in and out-of-plane magnetization can be continuously tuned while
+their ratio stays constant. Furthermore, different low-temperature magnetic
+behaviors are evidenced for strained and relaxed films, suggesting that the
+strain-induced structural state impacts the magnetic phase stability.",2206.15071v1
+2022-07-06,How fluid-mechanical erosion creates anisotropic porous media,"Using a Cauchy integral formulation of the boundary integral equations, we
+simulate the erosion a porous medium comprised of up to 100 solid bodies
+embedded in a Stokes flow. The grains of the medium are resolved individually
+and erode under the action of surface shear stress. Through nonlinear feedback
+with the surrounding flow fields, microscopic changes in grain morphology give
+way to larger-scale features in the medium such as channelization. The
+Cauchy-integral formulation and associated quadrature formulas enable us to
+resolve dense configurations of nearly contacting bodies. We observe
+substantial anisotropy to develop over the course of erosion; that is, the
+configurations that result from erosion generally permit flow in the
+longitudinal direction more easily than in the transverse direction by up to a
+factor of six. These results suggest that the erosion of solid material from
+groundwater flows may contribute to previously observed anisotropy of natural
+porous media.",2207.02418v1
+2022-07-06,Stress anisotropy in confined populations of growing rods,"Order and alignment are ubiquitous in growing colonies of rod-shaped bacteria
+due to the nematic properties of the constituent particles. These effects are
+the result of the active stresses generated by growth, passive mechanical
+interactions between cells, and flow-induced effects due to the shape of the
+confining container. However, how these contributing factors interact to give
+rise to the observed global alignment patterns remains elusive. Here, we study,
+in-silico, colonies of growing rod-shaped particles of different aspect ratios
+confined in channel-like geometries. A spatially resolved analysis of the
+stress tensor reveals a strong relationship between near-perfect alignment and
+an inversion of stress anisotropy for particles with large length-to-width
+ratios. We show that, in quantitative agreement with an asymptotic theory,
+strong alignment can lead to a decoupling of active and passive stresses
+parallel and perpendicular to the direction of growth, respectively. We
+demonstrate the robustness of these effects in a geometry that provides less
+restrictive confinement and introduces natural perturbations in alignment. Our
+results illustrate the complexity arising from the inherent coupling between
+nematic order and active stresses in growing active matter which is modulated
+by geometric and configurational constraints due to confinement.",2207.02607v1
+2022-07-08,2n-Stream Conservative Scattering,"We show how to use matrix methods of quantum mechanics to efficiently and
+accurately calculate axially symmetric radiation transfer in clouds, with
+conservative scattering of arbitrary anisotropy. Analyses of conservative
+scattering, where the single scattering albedo is $\tilde\omega =1$ and no
+energy is exchanged between the radiation and scatterers, began with work by
+Schwarzschild, Milne, Eddington and others on radiative transfer in stars.
+There the scattering is isotropic or nearly so. It has been difficult to extend
+traditional methods to highly anisotropic scattering, like that of sunlight in
+Earth's clouds. The $2n$-stream method described here is a practical way to
+handle highly anisotropic, conservative scattering. The basic ideas of the
+$2n$-stream method are an extension of Wick's seminal work on transport of
+thermal neutrons by isotropic scattering to scattering with arbitrary
+anisotropy. How to do this for finite absorption and $\tilde\omega<1$ was
+described in our previous paper (arXiv:2205.09713v2). But those methods fail
+for conservative scattering, when $\tilde \omega = 1$. Here we show that minor
+modifications to the fundamental $2n$-scattering theory for $\tilde\omega <1$
+make it suitable for $\tilde\omega = 1$.",2207.03978v1
+2022-07-11,Bandwidth controlled quantum phase transition between an easy-plane quantum spin Hall state and an s-wave superconductor,"The quantum spin Hall state can be understood in terms of spontaneous O(3)
+symmetry breaking. Topological skyrmion configurations of the O(3) order
+parameter vector carry a charge 2e, and as shown previously, when they
+condense, a superconducting state is generated. We show that this topological
+route to superconductivity survives easy-plane anisotropy. Upon reducing the
+O(3) symmetry to O(2)$\times$ Z$_2$, skyrmions give way to merons that carry a
+unit charge. On the basis of large-scale auxiliary field quantum Monte Carlo
+simulations, we show that at the particle-hole symmetric point, we can trigger
+a continuous and direct transition between the quantum spin Hall state and
+s-wave superconductor by condensing pairs of merons. This statement is valid in
+both strong and weak anisotropy limits. Our results can be interpreted in terms
+of an easy-plane deconfined quantum critical point. However, in contrast to the
+previous studies in quantum spin models, our realization of this quantum
+critical point conserves $U(1)$ charge, such that skyrmions are conserved.",2207.04803v3
+2022-07-13,Experimental Determination of a Single Atom Ground State Orbital through Hyperfine Anisotropy,"Historically, electron spin resonance (ESR) has provided excellent insight
+into the electronic, magnetic, and chemical structure of samples hosting spin
+centers. In particular, the hyperfine interaction between the electron and the
+nuclear spins yields valuable structural information of these centers. In
+recent years, the combination of ESR and scanning tunneling microscopy
+(ESR-STM) has allowed to acquire such information on individual spin centers of
+magnetic atoms bound atop a surface, while additionally providing spatial
+information about the binding site. Here, we conduct a full angle-dependent
+investigation of the hyperfine splitting for individual titanium atoms on
+MgO/Ag(001) by measurements in a vector magnetic field. We observe strong
+anisotropy in both the g-factor and the hyperfine tensor. Combining the results
+of the hyperfine splitting with the symmetry properties of the binding site
+obtained from STM images and a basic point charge model allows us to predict
+the shape of the electronic ground state configuration of the titanium atom.
+Relying on experimental values only, this method paves the way for a new
+protocol for electronic structure analysis for spin centers on surfaces.",2207.06037v2
+2022-07-28,Holographic Study of Reflected Entropy in Anisotropic Theories,"We evaluate reflected entropy in certain anisotropic boundary theories dual
+to nonrelativistic geometries using holography. It is proposed that this
+quantity is proportional to the minimal area of the entanglement wedge cross
+section. Using this prescription, we study in detail the effect of anisotropy
+on reflected entropy and other holographic entanglement measures. In
+particular, we study the discontinuous phase transition of this quantity for a
+symmetric configuration consisting of two disjoint strips. We find that in the
+specific regimes of the parameter space the critical separation is an
+increasing function of the anisotropy parameter and hence the correlation
+between the subregions becomes more pronounced. We carefully examine how these
+results are consistent with the behavior of other correlation measures
+including the mutual information. Finally, we show that the structure of the
+universal terms of entanglement entropy is corrected depending on the
+orientation of the entangling region with respect to the anisotropic direction.",2207.14169v1
+2022-07-29,On the bending of rectangular atomic monolayers along different directions: an ab initio study,"We study the bending of rectangular atomic monolayers along different
+directions from first principles. Specifically, choosing the phosphorene, GeS,
+TiS$_3$, and As$_2$S$_3$ monolayers as representative examples, we perform
+Kohn-Sham density functional theory calculations to determine the variation in
+transverse flexoelectric coefficient and bending modulus with the direction of
+bending. We find that while the flexoelectric coefficient is nearly isotropic,
+there is significant and complex anisotropy in bending modulus that also
+differs between the monolayers, with extremal values not necessarily occurring
+along the principal directions. In particular, the commonly adopted orthotropic
+continuum plate model with uniform thickness fails to describe the observed
+variations in bending modulus for GeS, TiS$_3$, and As$_2$S$_3$. We determine
+the direction-dependent effective thickness for use in such continuum models.
+We also show that the anisotropy in bending modulus is not associated with the
+rehybridization of atomic orbitals.",2208.00091v2
+2022-07-30,Skyrmion pinning by disk-shaped defects,"High precision skyrmion pinning by an intentionally created magnetic
+structure is important in skyrmion manipulation. Here, we consider skyrmion
+pinning by various types of disks. Among other findings, we clarify that, in
+terms of pinning position and pinning potential landscape, one needs to
+distinguish thin-wall skyrmions from thick-wall skyrmions because of
+fundamental differences. A skyrmion wall prefers areas with a weaker exchange
+stiffness, a larger DMI constant, or a smaller magnetic anisotropy while a
+skyrmion core experiences only the magnetic anisotropy, not exchange stiffness
+and DMI. Depending on disk type, skyrmion type, and the relative size of the
+disk (to skyrmion), a skyrmion can be pinned at the symmetric (center) or
+asymmetric (off-center) point of a disk. In case a skyrmion is pinned by a
+local energy minimum, thermal agitation can depin the skyrmion, and the pinning
+lifetime follows an Arrhenius law. Interestingly, when the disk size is
+comparable to the skyrmion size, the skyrmion deforms greatly such that the
+skyrmion will shrink or expand to fill the whole disk. These findings should be
+important for skyrmion manipulations.",2208.00178v1
+2022-07-24,Ion-Beam Radiation-Induced Eshelby Transformations: The Mean and Variance in Hydrostatic and Shear Residual Stresses,"Ion beam plays a pivotal role in ion implantations and the fabrication of
+nanostructures. However, there lacks a quantitative model to describe the
+residual stresses associated with the ion-beam radiation. Radiation-induced
+residual stress/transformation strain have been mostly recognized in the
+hydrostatic sub strain space. Here, we use molecular dynamics (MD) simulations
+to show that the response of a material to irradiation is generally anisotropic
+that depends on the ion-beam direction, and should be described using tensorial
+quantities. We demonstrate that accelerator-based ion beam irradiation,
+combined with the intrinsic lattice anisotropy and externally induced
+anisotropy (such as anisotropic mechanical loadings), causes radiation-actuated
+shear transformation strains in addition to hydrostatic expansion. We map out
+these complex correlations for several materials. Radiation-induced defects are
+shown to be responsible for residual shear stresses in the manner of Eshelby
+inclusion transformation. We propose such tensorial response model should be
+considered for accurate nanoscale fabrication using ion-beam irradiation.",2208.04147v1
+2022-08-09,Momentum broadening of heavy quarks and jets in the Glasma from classical colored particle simulations,"We investigate the effects of the pre-equilibrium Glasma stage of heavy-ion
+collisions on the broadening of momentum for heavy quarks and jets using
+classical colored particle simulations based on Wong's equations. Confirming
+previous studies, we find that these probes accumulate momentum on the order of
+the saturation scale $Q_s$ and that the color field of the Glasma induces an
+anisotropy with more broadening along the beam axis. For quark jets the
+anisotropy is more pronounced at lower energies.",2208.04781v1
+2022-08-09,Geometric-anisotropy induced high-order topological insulators in nonsymmorphic photonic crystals,"To a significant extent, the rich physical properties of photonic crystals
+are determined by the underlying geometry, in which the composed symmetry
+operators and their combinations contribute to the unique topological invariant
+to characterize the topological phases. Particularly, the inter- and
+intra-coupling modulation in the two-dimensional (2D) Su-Schrieffer-Heeger
+model yields the topological phase transition, and exhibit first-order edge
+localized states and second-order corner localized corner states. In this work,
+we use the geometric anisotropy into the 2D square lattice composed of four
+rectangle blocks. We show a variety of topological phase transitions in
+designed nonsymmorphic photonic crystals (PCs) and these transitions shall be
+understood in terms of the Zak phase and Chern number in synthetic space, as
+well as the pseudospin-2 concept, combinationally. Furthermore, Zak phase
+winding in the periodic synthetic parameter space yields high-order Chern
+number and double interface states. Based on the extended Zak phase and
+pseudo-spin Hall effect, higher-order topological insulator is constructed in
+the PC system. The intriguing and abundant topological features are also
+sustained in the corresponding three-dimensional PC slab, which makes it a very
+interesting platform to control the flow of optical signals.",2208.04816v1
+2022-08-11,Magnetic-field-induced ab-plane rotation of the Eu magnetic moments in trigonal EuMg2Bi2 and EuMg2Sb2 single crystals below their Neel temperatures,"The thermodynamic and electronic-transport properties of trigonal EuMg2Bi2 in
+ab-plane magnetic fields Hx and the A-type antiferromagnetic structure have
+recently been reported. At a temperature of 1.8 K < TN, the Eu magnetic moments
+with spin S = 7/2 remain locked in the ab plane up to and above the ab-plane
+critical field Hxc = 27.5 kOe at which the Eu moments become parallel to Hx.
+Here additional measurements at low fields are reported that reveal a new
+spin-reorientation transition at a field Hc1 = 465 Oe where the Eu moments
+remain in the ab plane but become perpendicular to Hx. At higher fields, the
+moments cant towards the field resulting in M proportional to Hx up to Hxc.
+Similar results are reported from measurements of the magnetic properties of
+EuMg2Sb2 single crystals, where Hc1 = 220 Oe is found. Theory is formulated
+that models the low-field magnetic behavior of both materials, and the
+associated anisotropies are calculated. The ab-plane trigonal anisotropy in
+EuMg2Sb2 is found to be significantly smaller than in EuMg2Bi2.",2208.06020v1
+2022-08-17,Thermoviscous Hydrodynamics in Non-Degenerate Dipolar Bose Gases,"We present a hydrodynamic model of ultracold, but not yet quantum condensed,
+dipolar Bosonic gases. Such systems present both $s$-wave and dipolar
+scattering, the latter of which results in anisotropic transport tensors of
+thermal conductivity and viscosity. This work presents an analytic derivation
+of the viscosity tensor coefficients, utilizing the methods established in
+[Wang et al., arXiv:2205.10465], where the thermal conductivities were derived.
+Taken together, these transport tensors then permit a comprehensive description
+of hydrodynamics that is now embellished with dipolar anisotropy. An analysis
+of attenuation in linear waves illustrates the effect of this anisotropy in
+dipolar fluids, where we find a clear dependence on the dipole orientation
+relative to the direction of wave propagation.",2208.08353v1
+2022-08-18,Shear hardening in frictionless amorphous solids near the jamming transition,"The jamming transition, generally manifested by a rapid increase of rigidity
+under compression (i.e., compression hardening), is ubiquitous in amorphous
+materials. Here we study shear hardening in deeply annealed frictionless
+packings generated by numerical simulations, reporting critical scalings absent
+in compression hardening. We demonstrate that hardening is a natural
+consequence of shear-induced memory destruction. Based on an elasticity theory,
+we reveal two independent microscopic origins of shear hardening: (i) the
+increase of the interaction bond number and (ii) the emergence of anisotropy
+and long-range correlations in the orientations of bonds, the latter highlights
+the essential difference between compression and shear hardening. Through the
+establishment of physical laws specific to anisotropy, our work completes the
+criticality and universality of jamming transition, and the elasticity theory
+of amorphous solids.",2208.08793v2
+2022-08-21,Enhanced magnetoresistance in perpendicular magnetic tunneling junctions with MgAl2O4 barrier,"Perpendicular magnetic tunnel junction with MgAl2O4 barrier is investigated.
+It is found that reactive RF sputtering with O2 is essential to obtain strong
+perpendicular magnetic anisotropy and large tunneling magnetoresistance in
+MgAl2O4-based junctions. An interfacial perpendicular magnetic anisotropy
+energy density of 2.25 mJ/m2 is obtained for the samples annealed at 400C. An
+enhanced magnetoresistance of 60% has also been achieved. The Vhalf, bias
+voltage at which tunneling magnetoresistance drops to half of the zero-bias
+value, is found to be about 1V, which is substantially higher than that of
+MgO-based junctions.",2208.09947v1
+2022-08-22,"Current-induced magnetization reversal in (Ga,Mn)(Bi,As) epitaxial layer with perpendicular magnetic anisotropy","Pulsed current-induced magnetization reversal is investigated in the layer of
+(Ga,Mn)(Bi,As) dilute ferromagnetic semiconductor (DFS) epitaxially grown under
+tensile misfit strain causing perpendicular magnetic anisotropy in the layer.
+The magnetization reversal, recorded through measurements of the anomalous Hall
+effect, appearing under assistance of a static magnetic field parallel to the
+current, is interpreted in terms of the spin-orbit torque mechanism. Our
+results demonstrate that an addition of a small fraction of heavy Bi atoms,
+substituting As atoms in the prototype DFS (Ga,Mn)As and increasing the
+strength of spin-orbit coupling in the DFS valence band, significantly enhances
+the efficiency of current-induced magnetization reversal thus reducing
+considerably the threshold current density necessary for the reversal. Our
+findings are of technological importance for applications to spin-orbit
+torque-driven nonvolatile memory and logic elements.",2208.10318v1
+2022-08-23,Anisotropic inflation in non-minimal kinetic coupling model,"We study anisotropic inflation in non-minimal derivative coupling model where
+the scalar field non-minimally coupled to the $U(1)$ gauge fields and
+derivative of the scalar field non-minimally coupled to the Einstein tensor.
+Within the framework we find power-law anisotropic solutions in this model when
+both the inflaton potential and the gauge kinetic function are power-law type
+in the high friction regime. We show the ratio of anisotropy to the expansion
+rate is nearly constant, small and proportional to the slow-roll parameters of
+the theory. As a demonstration, we consider numerically calculation of the
+model to show that the behavior of anisotropy by changing the parameters of the
+model for quadratic inflationary potential. There is anisotropic attractor
+solution for a wide range of values of the model parameters. We show both
+numerically and analytically that there are two phases of inflation, similar to
+those an anisotropic inflation in minimal coupling model, isotropic and
+anisotropic phase. We can change the number of e-folds corresponding to each
+phase of slow roll inflation by changing the gauge coupling constant or
+non-minimal derivative coupling constant. There are the best agreement with the
+numerically solutions and analytically solutions in this investigation.",2208.10757v2
+2022-08-26,Geostatistics for large datasets on Riemannian manifolds: a matrix-free approach,"Large or very large spatial (and spatio-temporal) datasets have become common
+place in many environmental and climate studies. These data are often collected
+in non-Euclidean spaces (such as the planet Earth) and they often present
+non-stationary anisotropies. This paper proposes a generic approach to model
+Gaussian Random Fields (GRFs) on compact Riemannian manifolds that bridges the
+gap between existing works on non-stationary GRFs and random fields on
+manifolds. This approach can be applied to any smooth compact manifolds, and in
+particular to any compact surface. By defining a Riemannian metric that
+accounts for the preferential directions of correlation, our approach yields an
+interpretation of the ''local anisotropies'' as resulting from ''local''
+deformations of the domain. We provide scalable algorithms for the estimation
+of the parameters and for optimal prediction by kriging and simulation able to
+tackle very large grids. Stationary and non-stationary illustrations are
+provided.",2208.12501v2
+2022-08-28,Mechanical Anisotropy and Multiple Direction-Dependent Dirac States in the Synthesized Ag3C20 Monolayer,"Recently, a 2D orthorhombic silver-organic framework, Ag3C20 monolayer, was
+synthesized by assembling organic molecules linked with multiple aryl-metal
+bonds. Herein, via first-principles study, we demonstrate that owing to the
+unique bonding feature, Ag3C20 monolayer not only exhibits strong mechanical
+anisotropy, but also possesses various tunable direction-dependent Dirac
+states. Around the Fermi level blow, the intrinsic Dirac points form two
+antiparallel quasi type-III nodal lines protected by mirror symmetry, which can
+further evolve into hybrid nodal loops under tiny strains. Intriguingly, near
+the Fermi level above, a special semi-Dirac state can emerge under a critical
+strain by merging two type-I Dirac cone, which harbors direction-dependent
+strongly localized fermions, normal massive carries, and ultrafast Dirac
+fermions at the same time. These findings suggest that the mechanically
+sensitive Ag3C20 monolayer is a promising 2D material to realize the
+interesting Dirac physics and highly anisotropic multiple carries transport.",2208.13202v1
+2022-09-05,Generation and routing of nanoscale droplet solitons without compensation of magnetic damping,"Magnetic droplet soliton is a localized dynamic spin state which can serve as
+a nanoscale information carrier and nonlinear oscillator. The present opinion
+is that the formation of droplet solitons requires the compensation of magnetic
+damping by a torque created by a spin-polarized electric current or pure spin
+current. Here we demonstrate theoretically that nanoscale droplet solitons can
+be generated and routed in ferromagnetic nanostructures with voltage-controlled
+magnetic anisotropy in the presence of uncompensated magnetic damping.
+Performing micromagnetic simulations for the MgO/Fe/MgO trilayer with almost
+perpendicular-to-plane magnetization, we reveal the formation of the droplet
+soliton under a nanoscale gate electrode subjected to a sub-nanosecond voltage
+pulse. The soliton lives up to 50 ns at room temperature and can propagate over
+micrometer distances in a ferromagnetic waveguide due to nonzero gradient of
+the demagnetizing field. Furthermore, we show that an electrical routing of the
+soliton to different outputs of a spintronic device can be realized with the
+aid of an additional semiconducting nanostripe electrode creating controllable
+gradient of the perpendicular magnetic anisotropy.",2209.01893v1
+2022-09-08,Transport anisotropy and metal-insulator transition in striped Dirac fermion systems,"Using the determinant quantum Monte Carlo method, we investigate the
+metal-insulator transitions induced by the stripe of charge density in an
+interacting two-dimensional Dirac fermion system. The stripe will introduce the
+transport anisotropy and insulating intermediate phase into the system,
+accompanied by the change of band structure and a peak of density of states
+around Fermi energy. In the case of strong correlation, stripe exhibits
+competition with Coulomb repulsion through closing the energy gap and
+disrupting the magnetic order, and finally drives the system in Mott insulating
+phase back to the metallic state. Our results may provide a feasible way to
+modify transport properties by setting charge stripes in experiments.",2209.03628v1
+2022-09-11,Production yield and azimuthal anisotropy measurements of strange hadrons from BES at STAR,"We report the production and azimuthal anisotropy measurements of strange and
+multi-strange hadrons at STAR BES energies. The $\Lambda/K^0_s$ ratio is
+reported at 3 GeV and observed to increase faster with transverse momentum than
+that at higher energies. The number-of-constituent quark (NCQ) scaling of $v_2$
+has been studied at 19.6 GeV (BES-II). The NCQ scaling holds for particles and
+anti-particles, which can be considered as an evidence of partonic
+collectivity. The production of $K^{*0}$ resonance is also reported for 7.7-39
+GeV (BES-I) and the $K^{*0}/K$ ratio suggests that hadronic re-scattering
+dominates over regeneration in central A+A collisions. Using the $K^{*0}/K$
+ratio, we also report the lower limit of hadronic phase lifetime $( t_{kin} -
+t_{chem} )$.",2209.04863v1
+2022-09-12,State Space Geometry of the Spin-1 Antiferromagnetic Heisenberg Chain,"We study the phase diagram of the spin-1 antiferromagnetic Heisenberg chain
+with uniaxial anisotropy and applied magnetic field in terms of the genuine
+multipartite entanglement as witnessed by the mean quantum Fisher information
+density. By generalizing the manifold studied in [1, 2] to the many body case
+for spin 1, we connect the state space curvature in the vicinity of the ground
+state of the Heisenberg chain to the genuine multipartite entanglement. Our
+analysis demonstrates that the quantum critical points and symmetry protected
+topological (SPT) phase exhibit large state space curvature, while the
+separable phases are completely flat, offering insight into the physical
+interpretation of state space curvature. We further show that the entanglement
+in the SPT phase is enhanced by the presence of uniaxial anisotropy, and
+undiminished in the presence of uniform magnetic fields. The magnon condensate
+phase induced by large fields is shown to emanate from the Gaussian critical
+point, and exhibits massive multipartite entanglement over a robust region of
+the parameter space.",2209.05005v4
+2022-09-15,The Schönberg-Chandrasekhar limit in presence of small anisotropy and modified gravity,"The Sch\""{o}nberg-Chandrasekhar limit in post main sequence evolution for
+stars of masses in the range $1.4\lesssim M/M_{\odot}\lesssim 6$ gives the
+maximum pressure that the stellar core can withstand, once the central hydrogen
+is exhausted. It is usually expressed as a quadratic function of $1/\alpha$,
+with $\alpha$ being the ratio of the mean molecular weight of the core to that
+of the envelope. Here, we revisit this limit in scenarios where the pressure
+balance equation in the stellar interior may be modified, and in the presence
+of small stellar pressure anisotropy, that might arise due to several physical
+phenomena. Using numerical analysis, we derive a three parameter dependent
+master formula for the limit, and discuss various physical consequences. As a
+byproduct, in a limiting case of our formula, we find that in the standard
+Newtonian framework, the Sch\""{o}nberg-Chandrasekhar limit is best fitted by a
+polynomial that is linear, rather than quadratic, to lowest order in
+$1/\alpha$.",2209.07389v2
+2022-09-19,Emergent isotropy of a wave-turbulent cascade in the Gross-Pitaevskii model,"The restoration of symmetries is one of the most fascinating properties of
+turbulence. We report a study of the emergence of isotropy in the
+Gross-Pitaevskii model with anisotropic forcing. Inspired by recent
+experiments, we study the dynamics of a Bose-Einstein condensate in a
+cylindrical box driven along the symmetry axis of the trap by a spatially
+uniform force. We introduce a measure of anisotropy $A(k,t)$ defined on the
+momentum distributions $n(\boldsymbol{k},t)$, and study the evolution of
+$A(k,t)$ and $n(\boldsymbol{k},t)$ as turbulence proceeds. As the system
+reaches a steady state, the anisotropy, large at low momenta because of the
+large-scale forcing, is greatly reduced at high momenta. While
+$n(\boldsymbol{k},t)$ exhibits a self-similar cascade front propagation,
+$A(k,t)$ decreases without such self-similar dynamics. Finally, our numerical
+calculations show that the isotropy of the steady state is robust with respect
+to the amplitude of the drive.",2209.08973v2
+2022-09-19,Cavity-mediated superconductor$\unicode{x2013}$ferromagnetic insulator coupling,"A recent proof of concept showed that cavity photons can mediate
+superconducting (SC) signatures to a ferromagnetic insulator (FI) over a
+macroscopic distance [Phys. Rev. B, 102, 180506(R) (2020)]. In contrast with
+conventional proximity systems, this facilitates long-distance
+FI$\unicode{x2013}$SC coupling, local subjection to different drives and
+temperatures, and studies of their mutual interactions without proximal
+disruption of their orders. Here we derive a microscopic theory for these
+interactions, with an emphasis on the leading effect on the FI, namely, an
+induced anisotropy field. In an arbitrary practical example, we find an
+anisotropy field of $14 \unicode{x2013} 16$ $\mu$T, which is expected to yield
+an experimentally appreciable tilt of the FI spins for low-coercivity FIs such
+as Bi-YIG. We discuss the implications and potential applications of such a
+system in the context of superconducting spintronics.",2209.09308v2
+2022-09-25,Ring-originated anisotropy of local structural ordering in amorphous and crystalline silicon dioxide,"Rings comprising chemically bonded atoms are essential topological motifs for
+the structural ordering of network-forming materials. Quantification of such
+larger motifs beyond short-range pair correlation is essential for
+understanding the linkages between the orderings and macroscopic behaviors.
+Here, we propose two quantitative analysis methods based on rings. The first
+method quantifies rings by two geometric indicators: roundness and roughness.
+These indicators reveal the linkages between highly symmetric rings and crystal
+symmetry in silica and that the structure of amorphous silica mainly consists
+of distorted rings. The second method quantifies a spatial correlation function
+that describes three-dimensional atomic densities around rings. A comparative
+analysis among the functions for different degrees of ring symmetries reveals
+that symmetric rings contribute to the local structural order in amorphous
+silica. Another analysis of amorphous models with different orderings reveals
+anisotropy of the local structural ordering around rings; this contributes to
+building the intermediate-range ordering.",2209.12116v2
+2022-09-27,Leveraging Voltage-Controlled Magnetic Anisotropy to Solve Sneak Path Issues in Crossbar Arrays,"In crossbar array structures, which serves as an ""In-Memory"" compute engine
+for Artificial Intelligence hardware, write sneak path problem causes undesired
+switching of devices that degrades network accuracy. While custom crossbar
+programming schemes have been proposed, device level innovations leveraging
+non-linear switching characteristics of the cross-point devices are still under
+exploration to improve the energy efficiency of the write process. In this
+work, a spintronic device design based on Magnetic Tunnel Junction (MTJ)
+exploiting the use of voltage-controlled magnetic anisotropy (VCMA) effect is
+proposed as a solution to the write sneak path problem. Additionally, insights
+are provided regarding appropriate operating voltage conditions to preserve the
+robustness of the magnetization trajectory during switching which is critical
+for proper switching probability manipulation.",2209.13677v4
+2022-10-05,"Ln2(SeO3)2(SO4)(H2O)2 (Ln = Sm, Dy, Yb): A Mixed-Ligand Pathway to New Lathanide (III) Multifunctional Materials Featuring Nonlinear Optical and Magnetic Anisotropy Properties","Bottom-up assembly of optically nonlinear and magnetically anisotropic
+lanthanide materials involving precisely placed spin carriers and optimized
+metal-ligand coordination offers a potential route to developing electronic
+architectures for coherent radiation generation and spin-based technologies,
+but the chemical design historically has been extremely hard to achieve. To
+address this, we developed a worthwhile avenue for creating new
+noncentrosymmetric chiral Ln3+ materials Ln2(SeO3)2(SO4)(H2O)2 (Ln = Sm, Dy,
+Yb) by mixed-ligand design. The materials exhibit phase-matching nonlinear
+optical responses, elucidating the feasibility of the heteroanionic strategy.
+Ln2(SeO3)2(SO4)(H2O)2 displays paramagnetic property with strong magnetic
+anisotropy facilitated by large spin-orbit coupling. This study demonstrates a
+new chemical pathway for creating previously unknown polar chiral magnets with
+multiple functionalities.",2210.02342v1
+2022-10-09,Direct visualization and control of antiferromagnetic domains and spin reorientation in a parent cuprate,"We report magnetic optical second-harmonic generation (SHG) polarimetry and
+imaging on Sr$_2$Cu$_3$O$_4$Cl$_2$, which allows direct visualization of the
+mesoscopic antiferromagnetic (AFM) structure of a parent cuprate. Temperature-
+and magnetic-field-dependent SHG reveals large domains with 90$^{\circ}$
+relative orientations that are stabilized by a combination of uniaxial magnetic
+anisotropy and the Earth's magnetic field. Below a temperature $T_R$ $\sim$ 97
+K, we observe an unusual 90$^{\circ}$ spin reorientation transition, possibly
+driven by competing magnetic anisotropies of the two copper sublattices, which
+swaps the AFM domain states while preserving the domain structure. This allows
+deterministic switching of the AFM states by thermal or laser heating. Near
+$T_R$, the domain walls become exceptionally responsive to an applied magnetic
+field, with the Earth's field sufficient to completely expel them from the
+crystal. Our findings unlock opportunities to study the mesoscopic AFM behavior
+of parent cuprates and explore their potential for AFM technologies.",2210.04327v1
+2022-10-17,"Constraining Anisotropic Cosmological Model in $f(\mathcal{R},\mathscr{L}_m)$ Gravity","The observational evidence regarding the present cosmological aspects tells
+us about the presence of very little anisotropy in the universe on a large
+scale. Here, in this paper, we attempt to study locally rotationally symmetric
+(LRS) homogeneous Bianchi-I spacetime with the isotropic matter distribution.
+This is done within the framework of $f(\mathcal{R},\mathscr{L}_m)$ gravity.
+Particularly, we consider a non-linear $f(\mathcal{R},\mathscr{L}_m)$ model,
+$f(\mathcal{R},\mathscr{L}_m)=\dfrac{1}{2}\mathcal{R}+\mathscr{L}_m^{\,{\alpha}}$.
+Furthermore, $\omega$, the equation of state parameter, which is vital stuff in
+determining the present phase of the universe is constrained. To constrain the
+model parameters and the equation of state parameter, we use 57 Hubble data
+points and 1048 Pantheon supernovae type Ia data sample. And, for our
+statistical analysis, we use Markoc Chain Monte Carlo (MCMC) simulation.
+Moreover, with the help of obtained values of parameters, we measure the
+anisotropy parameter for our model.",2210.09307v1
+2022-10-22,Two-dimensional natural hyperbolic materials: From polaritons modulation to applications,"Natural hyperbolic materials (HMs) in two dimensions (2D) have an
+extraordinarily high anisotropy and a hyperbolic dispersion relation. Some of
+them can even sustain hyperbolic polaritons with great directional propagation
+and light compression to deeply sub-wavelength scales due to their inherent
+anisotropy. Herein, the anisotropic optical features of 2D natural HMs are
+reviewed. Four hyperbolic polaritons (i.e., phonon polaritons, plasmon
+polaritons, exciton-polaritons, and shear polaritons) as well as their
+generation mechanism are discussed in detail. The natural merits of 2D HMs hold
+promise for practical quantum photonic applications such as valley quantum
+interference, mid-infrared polarizer, spontaneous emission enhancement,
+near-field thermal radiation, and a new generation of optoelectronic
+components, among others. These analyses' conclusion outlines existing issues
+and potential interesting directions for 2D natural HMs. These findings could
+spur more interest in anisotropic 2D atomic crystals in the future, as well as
+the quick generation of natural HMs for new applications.",2210.12341v1
+2022-10-24,Reduction of energy cost of magnetization switching in a biaxial nanoparticle by use of internal dynamics,"A solution to energy-efficient magnetization switching in a nanoparticle with
+biaxial anisotropy is presented. Optimal control paths minimizing the energy
+cost of magnetization reversal are calculated numerically as functions of the
+switching time and materials properties, and used to derive energy-efficient
+switching pulses of external magnetic field. Hard-axis anisotropy reduces the
+minimum energy cost of magnetization switching due to the internal torque in
+the desired switching direction. Analytical estimates quantifying this effect
+are obtained based on the perturbation theory. The optimal switching time
+providing a tradeoff between fast switching and energy efficiency is obtained.
+The energy cost of switching and the energy barrier between the stable states
+can be controlled independently in a biaxial nanomagnet. This provides a
+solution to the dilemma between energy-efficient writability and good thermal
+stability of magnetic memory elements.",2210.13514v2
+2022-10-25,Radiant gravitational collapse with anisotropy in pressures and bulk viscosity,"We model a compact radiant star that undergoes gravitational collapse from a
+certain initial static configuration until it becomes a black hole. The star
+consists of a fluid with anisotropy in pressures, bulk viscosity, in addition
+to the radial heat flow. A solution of Einstein's field equations with temporal
+dependence was presented to study the dynamic evolution of physical quantities,
+such as the mass-energy function, the luminosity seen by an observer at
+infinity and the heat flow. We checked the acceptability conditions of the
+initial static configuration to obtain a range of mass-to-radius ratio in which
+the presented star model is physically reasonable. The energy conditions were
+analyzed for the dynamic case, in order to guarantee that the model is composed
+of a physically acceptable fluid within the range of the mass-to-radius ratio
+obtained for the static configuration or if they will be modified during the
+collapse",2210.14288v1
+2022-10-26,"Perpendicular magnetic anisotropy, tunneling magnetoresistance and spin-transfer torque effect in magnetic tunnel junctions with Nb layers","Nb and its compounds are widely used in quantum computing due to their high
+superconducting transition temperatures and high critical fields. Devices that
+combine superconducting performance and spintronic non-volatility could deliver
+unique functionality. Here we report the study of magnetic tunnel junctions
+with Nb as the heavy metal layers. An interfacial perpendicular magnetic
+anisotropy energy density of 1.85 mJ/m2 was obtained in Nb/CoFeB/MgO
+heterostructures. The tunneling magnetoresistance was evaluated in junctions
+with different thickness combinations and different annealing conditions. An
+optimized magnetoresistance of 120% was obtained at room temperature, with a
+damping parameter of 0.011 determined by ferromagnetic resonance. In addition,
+spin-transfer torque switching has also been successfully observed in these
+junctions with a quasistatic switching current density of 7.3*10^5 A/cm2.",2210.14969v1
+2022-10-28,"Pressure-dependent semiconductor-metal transition and elastic, electronic, optical, and thermophysical properties of SnS binary chalcogenide","Density functional theory based study of the pressure dependent physical
+properties of binary SnS compound has been carried out. The computed elastic
+constants reveal that SnS is mechanically stable and brittle under ambient
+conditions. With increasing pressure, the compound becomes ductile. The
+Poisson's ratio also indicates brittle-ductile transition with increasing
+pressure. The hardness of SnS increases significantly with pressure. The
+compound possesses elastic anisotropy. The ground state electronic band
+structure is semiconducting with a small band gap which becomes metallic under
+pressure. The band becomes more and more dispersive with the increase in
+pressure while the electronic correlations decrease as pressure is raised. Both
+the Debye temperature and the phonon thermal conductivity of SnS increase
+sharply with pressure. The Melting temperature of the compound is low. Mixed
+bonding characteristics are found with ionic and covalent contributions. SnS is
+a good absorber of ultraviolet light. The reflectivity of the material
+increases with the increase in pressure. The reflectivity is nonselective over
+a wide spectral range. The low energy refractive index is high. All these
+optical characteristics are useful for prospective optoelectronic device
+applications. The optical anisotropy is low.",2210.16055v1
+2022-10-28,The reconstructed CMB lensing bispectrum,"Weak gravitational lensing by the intervening large-scale structure (LSS) of
+the Universe is the leading non-linear effect on the anisotropies of the cosmic
+microwave background (CMB). The integrated line-of-sight mass that causes the
+distortion -- known as lensing convergence -- can be reconstructed from the
+lensed temperature and polarization anisotropies via estimators quadratic in
+the CMB modes, and its power spectrum has been measured from multiple CMB
+experiments. Sourced by the non-linear evolution of structure, the bispectrum
+of the lensing convergence provides additional information on late-time
+cosmological evolution complementary to the power spectrum. However, when
+trying to estimate the summary statistics of the reconstructed lensing
+convergence, a number of noise-biases are introduced, as previous studies have
+shown for the power spectrum. Here, we explore for the first time the
+noise-biases in measuring the bispectrum of the reconstructed lensing
+convergence. We compute the leading noise-biases in the flat-sky limit and
+compare our analytical results against simulations, finding excellent
+agreement. Our results are critical for future attempts to reconstruct the
+lensing convergence bispectrum with real CMB data.",2210.16203v1
+2022-11-02,Spin wave excitations in a nanowire spin-torque oscillator with perpendicular magnetic anisotropy,"Spin torque oscillators (STOs) are emerging microwave devices that can
+potentially be used in spin-logic devices and the next-generation high-speed
+computing architecture. Thanks to their non-linear nature, STOs are easily
+tunable by the magnetic field and the dc current. Spin Hall nano-oscillators
+(SHNOs) are promising types of STOs and most of the current studies focus on
+localized modes that can be easily excited. Here, we study using micromagnetic
+simulations, the nature of the spin-torque-induced excitations in nanowire
+devices made of perpendicular magnetic anisotropy (PMA) material. Our results
+showed that upon including PMA the excitation of localized and propagating spin
+wave modes is feasible. We study the nature of the mode excitations as a
+function of the PMA strength (\text{K}$_u$), and the current. Indeed, we
+estimate a critical value of \text{K}$_u$ to allow for the excitation of the
+propagating spin wave. We attribute this mode selectivity between localized and
+propagating modes to a switch in the sign of the nonlinearity of the system
+from negative to positive at a non-zero \text{K}$_u$ which is supported by
+analytical calculations. Our results provide deep insight into engineering
+reconfigurable microwave devices for future magnonic and computational
+applications.",2211.01078v1
+2022-11-03,Harmonics of Parton Saturation in Lepton-Jet Correlations at the EIC,"Parton saturation is one of the most intriguing phenomena in the high energy
+nuclear physics research frontier, especially in the upcoming era of the
+Electron-Ion Collider (EIC). The lepton-jet correlation in deep inelastic
+scattering provides us with a new gateway to the parton saturation at the EIC.
+In particular, we demonstrate that azimuthal angle anisotropies of the
+lepton-jet correlation are sensitive to the strength of the saturation momentum
+in the EIC kinematic region. In contrast to the predictions based on the
+collinear framework calculation, significant nuclear modification of the
+anisotropies is observed when we compare the saturation physics results in e +
+p and e + Au scatterings. By measuring these harmonic coefficients at the EIC,
+one can conduct quantitative analysis in different collisional systems and
+unveil compelling evidence for saturation effects.",2211.01647v4
+2022-11-07,Determining Perpendicular Magnetic Anisotropy in Fe/MgO/Fe Magnetic Tunnel Junction: A DFT-Based Spin-Orbit Torque Method,"In our JunPy package, we have combined the first-principles calculated
+self-consistent Hamiltonian with divide-and-conquer technique to successfully
+determine the magnetic anisotropy (MA) in an Fe/MgO/Fe magnetic tunnel junction
+(MTJ). We propose a comprehensive analytical derivation to clarify the crucial
+roles of spin-orbit coupling that mediates the exchange and spin-orbit
+components of spin torque, and the kinetic and spin-orbit components of spin
+current accumulation. The angular dependence of cumulative spin-orbit torque
+(SOT) indicates a uniaxial MA corresponding to the out-of-plane rotations of
+magnetic moments of the free Fe layers. Different from the conventional MA
+energy calculation and the phenomenological theory for a whole MTJ, our results
+provide insight into the orbital-resolved SOT for atomistic spin dynamics
+simulation in emergency complex magnetic heterojunctions.",2211.03603v3
+2022-11-09,Activated vortex lattice transition in a superconductor with combined sixfold and twelvefold anisotropic interactions,"Numerical simulations are used to examine the transition dynamics between
+metastable and ground state vortex lattice phases in a system with combined
+sixfold and twelvefold contributions to the vortex-vortex interactions. The
+system is initially annealed using a twelvefold anisotropy, yielding domains of
+two different orientations and separated by grain boundaries. The vortex-vortex
+interaction is then suddenly changed to a sixfold anisotropy, rendering the
+twelvefold state metastable. Applying a drive that mimics an oscillating
+magnetic field causes the metastable state to decay, indicated by the structure
+factor that evolves from twelve to six peaks. The results fit the behavior seen
+in recent small-angle neutron scattering studies of the vortex lattice in MgB2.
+At higher drive amplitudes, the decay exhibits a two step process in which the
+initial fast decrease is followed by a slower regime where avalanches or bursts
+are correlated with dislocation annihilation events. The results are compared
+to other types of metastable systems with quenched disorder that decay under a
+periodic external drive.",2211.05045v4
+2022-11-10,Giant magnetic anisotropy in the atomically thin van der Waals antiferromagnet FePS3,"Van der Waals (vdW) magnets are an ideal platform for tailoring
+two-dimensional (2D) magnetism with immense potential for spintronics
+applications and are intensively investigated. However, little is known about
+the microscopic origin of magnetic order in these antiferromagnetic systems. We
+used X-ray photoemission electron microscopy to address the electronic and
+magnetic properties of the vdW antiferromagnet FePS3 down to the monolayer. Our
+experiments reveal a giant out-of-plane magnetic anisotropy of 22 meV per Fe
+ion, accompanied by unquenched magnetic orbital moments. Moreover, our
+calculations suggest that the Ising magnetism in FePS3 is a visible
+manifestation of spin-orbit entanglement of the Fe 3d electron system.",2211.05381v1
+2022-11-12,Design of Spintronics-based Neuronal and Synaptic Devices for Spiking Neural Network Circuits,"Topologically stable magnetic skyrmion has a much lower depinning current
+density that may be useful for memory as well as neuromorphic computing.
+However, skyrmion-based devices suffer from the Magnus force originating from
+the skyrmion Hall effect, which may result in unwanted skyrmion annihilation if
+the magnitude of the driving current gets too large. A design of an artificial
+neuron and a synapse using a synthetic antiferromagnetically coupled bilayer
+device, which nullifies the Magnus force, is demonstrated in this work. The
+leak term in the artificial leaky integrate-and-fire neuron is achieved by
+engineering the uniaxial anisotropy profile of the neuronal device. The
+synaptic device has a similar structure as the neuronal device but has a
+constant uniaxial anisotropy. The synaptic device also has a linear and
+symmetric weight update, which is a highly desirable trait of an artificial
+synapse. Neuronal and synaptic devices based on magnetic domain-wall (DW)
+motion are also studied and compared to skyrmionic devices. Our simulation
+results show the energy required to perform such operation in DW or
+skyrmion-based devices is on the order of a few fJ.",2211.06630v1
+2022-11-16,Power-law decay of correlations after a global quench in the massive XXZ chain,"We investigate the relaxation dynamics of equal-time correlations in the
+antiferromagnetic phase of the XXZ spin-1/2 chain following a global quantum
+quench of the anisotropy parameter. We focus, in particular, on the relaxation
+dynamics starting from an initial N\'eel state. Using state-of-the-art
+density-matrix renormalization group simulations, the exact solution of an
+effective free-fermion model, and the quench-action approach within the
+thermodynamic Bethe ansatz, we show that the late-time relaxation is
+characterized by a power-law decay $\sim t^{-3/2}$ independent of anisotropy.
+This is in contrast to the previously studied exponential decay of the
+antiferromagnetic order parameter. Remarkably, the effective model describes
+the numerical data extremely well even on a quantitative level if higher order
+corrections to the leading asymptotic behavior are taken into account.",2211.09204v2
+2022-11-19,Silicon anisotropy in a bi-dimensional optomechanical cavity,"In this work, we study the effects of mechanical anisotropy in a 2D
+optomechanical crystal geometry. We fabricate and measure devices with
+different orientations, showing the dependence of the mechanical spectrum and
+the optomechanical coupling with the relative angle of the device to the
+crystallography directions of silicon. Our results show that the device
+orientation strongly affects its mechanical band structure, which makes the
+devices more susceptible to fabrication imperfections. Finally, we show that
+our device is compatible with cryogenic measurements reaching ground state
+occupancy of 0.2 phonons at mK temperature.",2211.10573v1
+2022-11-21,A Continuous $hp-$Mesh Model for Discontinuous Petrov-Galerkin Finite Element Schemes with Optimal Test Functions,"We present an anisotropic $hp-$mesh adaptation strategy using a continuous
+mesh model for discontinuous Petrov-Galerkin (DPG) finite element schemes with
+optimal test functions, extending our previous work on $h-$adaptation. The
+proposed strategy utilizes the inbuilt residual-based error estimator of the
+DPG discretization to compute both the polynomial distribution and the
+anisotropy of the mesh elements. In order to predict the optimal order of
+approximation, we solve local problems on element patches, thus making these
+computations highly parallelizable. The continuous mesh model is formulated
+either with respect to the error in the solution, measured in a suitable norm,
+or with respect to certain admissible target functionals. We demonstrate the
+performance of the proposed strategy using several numerical examples on
+triangular grids.
+  Keywords: Discontinuous Petrov-Galerkin, Continuous mesh models, $hp-$
+adaptations, Anisotropy",2211.11156v1
+2022-11-23,Density jump for oblique collisionless shocks in pair plasmas: allowed solutions,"Shockwaves in plasma are usually dealt with using Magnetohydrodynamics (MHD).
+Yet, MHD entails the assumption of a short mean free path, which is not
+fulfilled in a collisionless plasma. Recently, for pair plasmas, we devised a
+model allowing to account for kinetic effects within an MHD-like formalism. Its
+relies on an estimate of the anisotropy generated when crossing the front, with
+a subsequent assessment of the stability of this anisotropy in the downstream.
+We solved our model for parallel, perpendicular and switch-on shocks. Here we
+bridge between all these cases by treating the problem of an arbitrarily, but
+coplanar, oriented magnetic field. Even though the formalism presented is valid
+for anisotropic upstream temperatures, only the case of a cold upstream is
+solved. We find extra solutions which are not part of the MHD catalog, and a
+density jump that is notably less in the quasi parallel, highly magnetized,
+regime. Given the complexity of the calculations, this work is mainly devoted
+to the presentation of the mathematical aspect of our model. A forthcoming
+article will be devoted to the physics of the shocks here defined.",2211.12876v1
+2022-11-23,A study of the relativistic corrections to polarized tritium $β$-decay,"Forthcoming experiments like Project8 and Ptolemy aim at investigating with
+high precision the end-point of the tritium $\beta$-decay spectrum sensitive to
+the neutrino mass. In light of this, using the standard parametrization in
+terms of nuclear polar form factors, we analyze the complete relativistic
+expression for the spectrum of the $\beta$-electron emitted by a tritium
+nucleus. Given the small parameters in the problem, we systematically discuss
+the approximations that can be made, and present the first two corrections to
+the standard lowest order formula. We particularly discuss the case of an
+initially polarized target, and the consequences on the spectrum as a function
+of the neutrino mass. We show that, while it induces an angular anisotropy that
+can be measured by future experiments, such anisotropy cannot be used as an
+additional handle to constrain the neutrino mass.",2211.13247v3
+2022-11-25,Microscopic parameters of the van der Waals CrSBr antiferromagnet from microwave absorption experiments,"Microwave absorption experiments employing a phase-sensitive external
+resistive detection are performed for a topical van der Waals antiferromagnet
+CrSBr. The field dependence of two resonance modes is measured in an applied
+field parallel to the three principal crystallographic directions, revealing
+anisotropies and magnetic transitions in this material. To account for the
+observed results, we formulate a microscopic spin model with a bi-axial
+single-ion anisotropy and inter-plane exchange. Theoretical calculations give
+an excellent description of full magnon spectra enabling us to precisely
+determine microscopic interaction parameters for CrSBr.",2211.14117v1
+2022-11-27,Holographic energy loss near critical temperature in an anisotropic background,"We study the energy loss of a quark moving in a strongly coupled QGP under
+the influence of anisotropy. The heavy quark drag force, diffusion coefficient,
+and jet quenching parameter are calculated using the Einstein-Maxwell-dilaton
+model, where the anisotropic background is characterized by an arbitrary
+dynamical parameter $A$.Our findings indicate that as the anisotropic factor
+$A$ increases, the drag force and jet quenching parameter both increase, while
+the diffusion coefficient decreases. Additionally, we observe that the energy
+loss becomes more significant when the quark moves perpendicular to the
+anisotropy direction in the transverse plane.The enhancement of the rescaled
+jet quenching parameters near critical temperature $T_c$, as well as drag
+forces for a fast-moving heavy quark is observed, which presents one of the
+typical features of QCD phase transition.",2211.14792v3
+2022-12-01,Invariant Data-Driven Subgrid Stress Modeling on Anisotropic Grids for Large Eddy Simulation,"We present a new approach for constructing data-driven subgrid stress models
+for large eddy simulation of turbulent flows using anisotropic grids. The key
+to our approach is a Galilean, rotationally, reflectionally and unit invariant
+model form that also embeds filter anisotropy in such a way that an important
+subgrid stress identity is satisfied. We use this model form to train a
+data-driven subgrid stress model using only a small amount of anisotropically
+filtered DNS data and a simple and inexpensive neural network architecture. A
+priori and a posteriori tests indicate that the trained data-driven model
+generalizes well to filter anisotropy ratios, Reynolds numbers and flow physics
+outside the training dataset.",2212.00332v2
+2022-12-01,Far-from-equilibrium slow modes and momentum anisotropy in expanding plasma,"The momentum distribution of particle production in heavy-ion collisions
+encodes information about thermalization processes in the early-stage
+quark-gluon plasma. We use kinetic theory to study the far-from-equilibrium
+evolution of an expanding plasma with an anisotropic momentum-space
+distribution. We identify slow and fast degrees of freedom in the
+far-from-equilibrium plasma from the evolution of moments of this distribution.
+At late times, the slow modes correspond to hydrodynamic degrees of freedom and
+are naturally gapped from the fast modes by the inverse of the relaxation time,
+$\tau_R^{-1}$. At early times, however, there are an infinite number of slow
+modes with a gap inversely proportional to time, $\tau^{-1}$. From the
+evolution of the slow modes we generalize the paradigm of the
+far-from-equilibrium attractor to vector and tensor components of the
+energy-momentum tensor, and even to higher moments of the distribution function
+that are not part of the hydrodynamic evolution. We predict that initial-state
+momentum anisotropy decays slowly in the far-from-equilibrium phase and may
+persist until the relaxation time.",2212.00820v1
+2022-12-05,Current-induced nucleation and motion of zero field skyrmion,"We study the stabilization and electrical manipulation of skyrmions in
+magnetic ultrathin films in the absence of an applied magnetic field. We show
+that this requires an increased magnetic anisotropy, controlled by the sample
+thickness, as compared to usual skyrmionic samples, so that the uniform state
+corresponds to the zero field ground state and the skyrmions to metastable
+excitations. Although skyrmion stabilization at zero field is demonstrated over
+a broad range of thicknesses, electrical control appeared to be more demanding
+to avoid skyrmion deformation. In the thinnest samples, the large magnetic
+anisotropy prevents skyrmion deformations and we show that they can be
+nucleated progressively by current pulses, which underlines that the only
+possible transition occurs between uniform and skyrmion states. The solitonic
+skyrmions in zero applied magnetic field have the same properties as compared
+to field stabilized ones, with a long-term stability and high mobility when
+excited by a spin-orbit torque.",2212.02351v1
+2022-12-13,Spin wave spectra of single crystal CoPS$_3$,"The spin waves in single crystals of the layered van der Waals
+antiferromagnet CoPS$_3$ have been measured using inelastic neutron scattering.
+The data show four distinct spin wave branches with large ($\gtrsim 14$ meV)
+energy gaps at the Brillouin zone center indicating significant anisotropy. The
+data were modelled using linear spin wave theory derived from a Heisenberg
+Hamiltonian. Exchange interactions up to the third nearest-neighbour in the
+layered planes were required to fit the data with ferromagnetic $J_1 = -1.37$
+meV between first neighbours, antiferromagnetic $J_3 = 3.0$ meV between third
+neighbours, and a very small $J_2 = 0.09$ meV between second neighbours. A
+biaxial single-ion anisotropy was required, with a collinear term $D^x = -0.77$
+meV for the axis parallel to the aligned moment direction and a coplanar term
+$D^z=6.07$ meV for an axis approximately normal to the layered crystal planes.",2212.06479v1
+2022-12-17,Zero-field miniature skyrmion crystal and chiral domain state in breathing-kagome antiferromagnets,"The stability of a miniature skyrmion crystal (SkX) with only a small number
+of spins in the magnetic unit cell has been theoretically investigated in
+$J_1$-$J_3$ antiferromagnets on the breathing kagome lattice with a single-ion
+anisotropy $D$ at zero field. It is found by means of Monte Carlo simulations
+that due to the breathing bond-alternation, a zero-field triple-${\bf Q}$
+miniature SkX can be stabilized not only in the specific case of $D=0$ [K.
+Aoyama and H. Kawamura, Phys. Rev. B 105, L100407 (2022)] but also in more
+general situations with easy-axis ($D<0$) and easy-plane ($D>0$) anisotropies
+which favor triple-${\bf Q}$ collinear and noncoplanar states, respectively.
+Since the SkX and anti-SkX each having positive or negative chirality are
+energetically degenerate, the topological Hall effect of alternative sign is
+possible at zero field. It is also found that reflecting the chiral degeneracy,
+the collinear and coplanar phases preempting the SkX phase possess random
+domain structures consisting of positive- and negative-chirality clusters.",2212.08778v2
+2022-12-17,Densely packed skyrmions stabilized at zero magnetic field by indirect exchange coupling in multilayers,"Room-temperature stabilization of skyrmions in magnetic multilayered systems
+is the result of a fine balance between different magnetic interactions namely
+symmetric and antisymmetric exchange, dipolar, perpendicular magnetic
+anisotropy as well as, in most cases, Zeeman through an applied external field.
+Such field-driven stabilization approach is not compatible with most of the
+anticipated skyrmion based applications, e.g. skyrmion memories, logic or
+neuromorphic computing which motivates a reduction or a cancellation of field
+requirements. Here we present a method to stabilize at room-temperature and
+zero-field, a densely packed skyrmion phase in ferromagnetic multilayers with
+moderate number of repetitions. To this aim, we finely tune the multilayer
+parameters to stabilize a dense skyrmion phase. Then, relying on the interlayer
+electronic coupling to an adjacent bias magnetic layer with strong
+perpendicular magnetic anisotropy and uniform magnetization, we demonstrate the
+stabilization of sub-60 nm diameter skyrmion at zero-field with adjustable
+skyrmion density.",2212.08920v1
+2022-12-19,Logarithmic negativity of the 1D antiferromagnetic spin-1 Heisenberg model with single-ion anisotropy,"We study the 1D antiferromagnetic spin-1 Heisenberg XXX model with external
+magnetic field B and single-ion anisotropy D on finite chains. We determine the
+nearest and non-nearest neighbor logarithmic entanglement LN. Our main result
+is the disappearance of LN both for nearest and non-nearest neighbor
+(next-nearest and next-next-nearest) sites at zero temperature and for low
+temperature states. Such disappearance occurs at a critical value of B and D.
+The resulting phase diagram for the behaviour of LN is discussed in the B - D
+plane, including a separating line - ending in a triple point - where the
+energy density is independent on the size. Finally, results for LN at finite
+temperature as a function of B and D are presented and commented.",2212.09511v4
+2022-12-19,Anisotropic fluctuations of angular momentum of heavy quarks in the Glasma,"We study the evolution of the angular momentum of the heavy quarks in the
+very early stage of high energy nuclear collisions, in which the background is
+made of evolving Glasma fields. Given the novelty of the problem, we limit
+ourselves to the use of toy heavy quarks with a large, unphysical mass, in
+order to implement the kinetic equations for the angular momentum in the
+non-relativistic limit. We find that as a consequence of the anisotropy of the
+background fields, angular momentum fluctuations are also anisotropic: we
+understand this in simple terms relating the fluctuations of the angular
+momentum, $L$, to those of linear momentum. While orbital angular momentum
+diffuses and develops substantial fluctuations and anisotropies, the spin does
+not. Hence, we can identify the fluctuations of $L$ with those of the total
+angular momentum $J=L + S$. Therefore, our study suggests that the total
+angular momentum of the heavy quarks in the early stage of high energy nuclear
+collisions will present anisotropic fluctuations.",2212.09725v1
+2022-12-19,"Anisotropic resistance with a 90-degree twist in a ferromagnetic Weyl semimetal, Co2MnGa","Co$_2$MnGa is a ferromagnetic semimetal with Weyl nodal lines identified by
+ARPES. We studied electrical transport in thin Co$_2$MnGa lamellae (10 $\times$
+10 $\times$ 0.4-5 microns) cut from single-crystals using a focused ion beam.
+These crystals exhibit an unexpected and highly unusual planar resistance
+anisotropy ($\sim$10 times) with principal axes that rotate by 90 degrees
+between the upper and lower faces. Using symmetry arguments and simulations, we
+find that the observed resistance anisotropy resembles that of an isotropic
+conductor with anisotropic surface states that are impeded from hybridization
+with bulk states. The origin of these states awaits further experiments that
+can correlate the surface bands with the observed 90$^\circ$-twist geometry.",2212.09738v1
+2022-12-20,Low $p_T$ direct photon production at RHIC measured with PHENIX,"PHENIX has used the versatility of RHIC to map out low $p_{T}$ direct photon
+production as function of collision system size and beam energy. For systems
+with a size corresponding to a $dN_{ch}/d\eta$ larger than 20-30, we observe a
+large yield of direct photons, a large azimuthal anisotropy with respect to the
+reaction plane, and a characteristic centrality dependence of $dN_{\gamma}/dy
+\propto (dN_{ch}/d\eta)^{\alpha}$, with $\alpha \sim$ 1.2. \\ In this
+proceeding, we will present new results from Au+Au collisions at
+$\sqrt{s_{NN}}$ = 39, 62.4 and 200 GeV. After subtracting the prompt photon
+component, the inverse slope for the $p_{T}$ range from 1-2 GeV/$c$ is 250
+MeV/$c$, but increases to about 400 MeV/$c$ for the range from 2 to 4 GeV/$c$.
+Within the experimental uncertainty, there is no indication of a system size
+dependence of the inverse slope. Furthermore, the system size dependence of the
+yield, expressed through the power $\alpha$, remains independent of $p_{T}$
+over the entire observed range from 1 to 6 GeV/$c$. Like the large yield and
+azimuthal anisotropy, these features, while qualitatively consistent with the
+emission of thermal photons from the quark gluon plasma, elude a quantitative
+description through theoretical model calculations.",2212.09953v1
+2022-12-20,Anisotropy distorts the spreading of a fixed volume porous gravity current,"We consider the release and subsequent gravity-driven spreading of a finite
+volume of fluid in an anisotropic porous medium bounded by an impermeable
+substrate. When the permeability in the vertical direction is much smaller than
+the horizontal direction, as is the case in many real geological reservoirs,
+this restricts the spread of the current to a very thin layer near the
+impermeable base. Using a combination of asymptotic analysis and finite
+difference computations of Darcy flow, we show that there exist two distinct
+flow regimes. At early times the bulk of the current descends slowly and
+uniformly, injecting fluid into thin finger-like regions near the base. At much
+later times the current transitions to the classical gravity-driven solution
+and continues to spread with a self-similar shape. One interesting consequence
+is that the swept volume of the current grows differently depending on the
+anisotropy of the medium. This has important consequences for managing
+contaminant spills, where it is important to minimise the contacted volume of
+the aquifer, or during geological CO$_2$ sequestration where a larger contacted
+volume results in more CO$_2$ being stored.",2212.10327v2
+2022-12-23,Azimuthal anisotropy of jet particles in p-Pb and Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV,"The azimuthal anisotropy of particles associated with jets (jet particles) at
+midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at
+$\sqrt{s_{\rm NN}}$ = 5.02 TeV down to transverse momentum ($p_{\rm T}$) of 0.5
+GeV/$c$ and 2 GeV/$c$, respectively, with ALICE. The second-order Fourier
+coefficient of the jet-particle azimuthal distribution ($v_2$) in
+high-multiplicity p-Pb collisions is positive, with a significance reaching
+6.8$\sigma$ at low $p_{\rm T}$. Comparisons with the inclusive charged-particle
+$v_2$ and with AMPT calculations are discussed. The model describes
+qualitatively the main features of the jet-particle $v_2$ in high-multiplicity
+p-Pb collisions and indicates that the positive jet-particle $v_2$ is generated
+by parton interactions.",2212.12609v1
+2022-12-28,Intrinsic orbital and spin Hall effect in bismuth semimetal,"We investigate the intrinsic orbital Hall conductivity (OHC) and spin Hall
+conductivity (SHC) in a bismuth semimetal, by employing an sp-orbital
+tight-binding model. We report a notable difference between the anisotropy of
+OHC and SHC whose orbital and spin polarizations lie within the basal plane. We
+do not observe a substantial correlation between the orbital and spin Berry
+curvatures with spin-orbit coupling (SOC) at the Fermi energy, disproving the
+correlation between OHC and SHC in a strong SOC regime. We argue the huge SHC
+in a Bi semimetal is attributed to its gigantic SOC which strongly affects the
+hybridization of the p orbitals, despite its relatively small magnitude of OHC.
+We hope the distinct anisotropy of OHC and SHC provides a feasible means to
+differentiate between the two effects in experiments.",2212.13891v2
+2022-12-28,Imprint of galactic rotation curves and metric fluctuations on the recombination era anisotropy,"In applications of the conformal gravity theory it has been shown that a
+scale of order 105 Mpc due to large scale inhomogeneities such as clusters of
+galaxies is imprinted on the rotation curves of galaxies. Here we show that
+this same scale is imprinted on recombination era anisotropies in the cosmic
+microwave background. We revisit an analysis due to Mannheim and Horne, to show
+that in the conformal gravity theory the length scale of metric signals that
+originate in the primordial nucleosynthesis era at $10^{9\circ}$K can fill out
+the entire recombination era sky. Similarly, the length scale of acoustic
+signals that originate at $10^{13\circ}$K can also fill out the entire
+recombination era sky. We show that the amplitudes of metric fluctuations that
+originate in the nucleosynthesis era can grow by a factor of $10^{12}$ at
+recombination, and by a factor of $10^{18}$ at the current time. In addition we
+find that without any period of exponential expansion a length scale as small
+as $10^{-33}$ cm can grow to the size of the recombination sky if it begins to
+grow at a temperature of order $10^{33}$ degrees.",2212.13942v1
+2022-12-31,Collective modes in the anisotropic collisional hot QCD medium at finite chemical potential,"We conducted a study on the collective modes within the hot QCD medium
+generated in heavy-ion collision experiments. These modes, whether real or
+imaginary, stable or unstable, play a crucial role in shaping the medium's
+evolution. To gain a deeper understanding, we considered several factors
+affecting the medium, including anisotropy, interactions among medium
+particles, and finite baryonic chemical potential. While the first two aspects
+have been thoroughly examined from various angles, the inclusion of finite
+chemical potential was previously overlooked. To provide a comprehensive
+analysis, we integrated these factors. The interactions among medium particles
+were accounted for using the BGK collisional kernel, while anisotropy and
+finite chemical potential were incorporated through the distribution functions
+of quarks, anti-quarks, and gluons. Our findings suggest that the presence of
+finite chemical potential amplifies the influence of unstable modes,
+potentially affecting the rapid thermalization of the hot QCD medium.
+Furthermore, exploring the implications of finite chemical potential in
+conjunction with other aspects of the created medium is intriguing,
+particularly in the context of low-energy heavy-ion collision experiments
+conducted at low temperatures and finite baryon density.",2301.00187v2
+2023-01-03,Spatially Varying Anisotropy for Gaussian Random Fields in Three-Dimensional Space,"Isotropic covariance structures can be unreasonable for phenomena in
+three-dimensional spaces such as the ocean. In the ocean, the variability of
+the response may vary with depth, and ocean currents may lead to spatially
+varying anisotropy. We construct a class of non-stationary anisotropic Gaussian
+random fields (GRFs) in three dimensions through stochastic partial
+differential equations (SPDEs) where computations are done using Gaussian
+Markov random field approximations.
+  The approach is proven in a simulation study where the amount of data
+required to estimate these models is explored. Then, the method is applied to
+construct a GRF prior on an ocean mass outside Trondheim, Norway, based on
+simulations from the complex numerical ocean model SINMOD. This GRF prior is
+compared to a stationary anisotropic GRF using in-situ measurements collected
+with an autonomous underwater vehicle where our approach outperforms the
+stationary anisotropic GRF for real-time prediction of unobserved locations.",2301.01372v2
+2023-01-05,Thomsen-type parameters and attenuation coefficients for constant-Q transverse isotropy,"Transversely isotropic (TI) media with the frequency-independent
+quality-factor elements (also called ``constant-$Q$'' transverse isotropy) are
+often used to describe attenuation anisotropy in sedimentary rocks. The
+attenuation coefficients in constant-$Q$ TI models can be conveniently defined
+in terms of the Thomsen-type attenuation-anisotropy parameters. Recent research
+indicates that not all those parameters for such constant-$Q$ media are
+frequency-independent. Here, we present concise analytic formulae for the
+Thomsen-type attenuation parameters for Kjartansson's constant-$Q$ TI model and
+show that one of them ($\delta_{Q}$) varies with frequency. The analytic
+expression for $\delta_{Q}$ helps evaluate the frequency dependence of the
+normalized attenuation coefficients of P- and SV-waves by introducing the newly
+defined ``dispersion factors''. Viscoacoustic constant-$Q$ transverse isotropy
+is also discussed as a special case, for which the elliptical condition and
+simplified expressions for the parameters $\delta$ and $\delta_{Q}$ are
+derived. Our results show that in the presence of significant absorption the
+attenuation coefficients of the ``constant-$Q$'' model vary with frequency for
+oblique propagation with respect to the symmetry axis. This variation needs to
+be taken into account when applying the spectral-ratio method and other
+attenuation-analysis techniques.",2301.01939v2
+2023-01-07,Geometric quantum discord and coherence in a dipolar interacting magnetic system,"The study of low-dimensional metal complexes has revealed fascinating
+characteristics regarding the ground-state crossover shown by spin-gaped
+systems. In this context, this work explores the effect of the quantum-level
+crossing, induced by the magnetic anisotropies of dipolar interacting systems,
+on the quantum discord and coherence of the system. The analytical expressions
+for the quantum discord, based on Schatten 1-norm, and the $l_1$ trace-norm
+quantum coherence for dinuclear spin-1/2 systems, are provided in terms of the
+magnetic anisotropies. The results show that, while the quantum discord has a
+clear signature of the quantum level-crossing, the basis dependence of the
+quantum coherence hides the crossover regarding the measured basis. In
+addition, the global quantum coherence is wholly stored within the correlations
+of the system, regardless of its reference basis.",2301.02891v1
+2023-01-10,Force-free current sheets in the Jovian magnetodisk: the key role of electron field-aligned anisotropy,"Current sheets are an essential element of the planetary magnetotails, where
+strong plasma currents self-consistently support magnetic field gradients. The
+current sheet configuration is determined by plasma populations that contribute
+to the current density. The most commonly investigated configuration is
+supported by diamagnetic cross-field currents of hot ions, typical for the
+magnetospheres of magnetized planets. In this study, we examine a new type of
+the current sheet configuration supported by field-aligned currents from
+electron streams in the Jovian magnetodisk. Such bi-directional streams
+increase the electron thermal anisotropy close to the fire-hose instability
+threshold and lead to strong magnetic field shear. The current sheet
+configuration supported by electron streams is nearly force-free, with B=const
+across the sheet. Using Juno plasma and magnetic field measurements, we
+investigate the internal structure of such current sheets and discuss possible
+mechanisms for their formation.",2301.03731v1
+2023-01-12,Cryogenic temperature deposition of high-performance CoFeB/MgO/CoFeB magnetic tunnel junctions on 300 mm wafers,"We developed a cryogenic temperature deposition process for high-performance
+CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) on 300 mm thermally oxidized
+silicon wafers. The effect of the deposition temperature of the CoFeB layers on
+the nanostructure, magnetic and magneto-transport properties of the MTJs were
+investigated in detail. When CoFeB was deposited at 100 K, the MTJs exhibited a
+perpendicular magnetic anisotropy (PMA) of 214 uJ/m2 and a voltage-controlled
+magnetic anisotropy (VCMA) coefficient of -45 fJ/Vm, corresponding to 1.4- and
+1.7-fold enhancements in PMA and VCMA, respectively, compared to the case of
+room-temperature deposition of CoFeB. The improvement in the MTJ properties was
+not simply due to the morphology of the MTJ films. The interface-sensitive
+magneto-transport properties indicated that interfacial qualities such as
+intermixing and oxidation states at the MgO/CoFeB interfaces were improved by
+the cryogenic temperature deposition. Cryogenic-temperature sputtering
+deposition is expected to be a standard manufacturing process for
+next-generation magnetoresistive random-access memory.",2301.04823v1
+2023-01-12,Investigating Dynamical Properties of Globular Clusters through a Family of Lowered Isothermal Models,"To investigate the dynamical properties of globular clusters, the surface
+brightness and kinematic data were collected and fitted to a family of lowered
+isothermal models called LIMEPY models. For 18 studied globular clusters, the
+amounts of concentration, truncation, and anisotropy were determined. In
+addition, the cluster mass, half-mass radius, distance, and mass-to-light ratio
+were also obtained. In general, LIMEPY models could describe these clusters
+well. Among these 18 clusters, NGC 5139, NGC 6388, and NGC 7078 were claimed to
+be candidates to host intermediate-mass black holes in literature. The models
+could not appropriately fit the central proper-motion velocity dispersion of
+NGC 5139 and the slope of proper-motion velocity-dispersion profile of NGC
+6388. Thus, more dedicated models with intermediate-mass black holes or a group
+of stellar-mass black holes at cluster centers may need to be considered.
+Considering NGC 7078, our model with some degree of anisotropy can fit the
+data. Finally, the strong concentration-truncation anti-correlation and
+truncation-semimajor-axis correlation were revealed, which could be the
+observational imprint of the dynamical evolution of globular clusters.",2301.04868v1
+2023-01-13,Multistep magnetization switching in orthogonally twisted ferromagnetic monolayers,"The advent of twist-engineering in two-dimensional (2D) crystals enables the
+design of van der Waals (vdW) heterostructures exhibiting emergent properties.
+In the case of magnets, this approach can afford artificial antiferromagnets
+with tailored spin arrangements. Here, we fabricate an orthogonally-twisted
+bilayer by twisting 90 degrees two CrSBr ferromagnetic monolayers with an
+easy-axis in-plane anisotropy. The magneto-transport properties reveal
+multistep magnetization switching with a magnetic hysteresis opening, that is
+absent in the pristine case. By tuning the magnetic field, we modulate the
+remanent state and coercivity and select between hysteretic and non-hysteretic
+magneto-resistance scenarios. This complexity pinpoints spin anisotropy as a
+key aspect in twisted magnetic superlattices. Our results highlight the control
+over the magnetic properties in vdW heterostructures, leading to a variety of
+field-induced phenomena and opening a fruitful playground for creating desired
+magnetic symmetries and manipulating non-collinear magnetic configurations.",2301.05647v2
+2023-01-16,Optical conductivity of the threefold Hopf semimetal,"A multifold Hopf semimetal is a topological point node semimetal possessing
+an anisotropy in the internal electronic structure, e.g., the dipole structure
+of the Berry curvature. In this paper, the unique features of threefold Hopf
+semimetals in terms of the optical conductivity are theoretically investigated
+with a minimal theoretical model by using linear response theory for a linearly
+polarized photon. The frequency spectrum of the optical conductivity shows an
+anisotropic dependence on the polarization angle of the incident photon even if
+the electronic band structure is completely isotropic. The longitudinal optical
+conductivity linearly depends on the photon frequency and possesses step-like
+changes in the frequency spectrum. The anisotropic electronic structure has a
+varying the number of steps with the orientation of the photon polarization
+axis. We reveal that the anisotropy is attributed to symmetries preserving the
+point node in threefold Hopf semimetals. The linearly polarized photon also
+induces a Hall current but it vanishes with the photon polarization axis
+parallel to the Berry dipole axis. The numerical calculations show that these
+characteristic features can be observed even with a non-zero temperature and
+disorder.",2301.06254v1
+2023-01-17,All-optical magneto-thermo-elastic skyrmion motion,"It is predicted magnetic skyrmions can be controllably moved on surfaces
+using a focused laser beam. Here an absorbed power of the order 1 mW, focused
+to a spot-size of the order 10 $\mu$m, results in a local temperature increase
+of around 50 K, and a local perpendicular strain of the order 10$^{-3}$ due to
+the thermo-elastic effect. For positive magneto-elastic coupling this generates
+a strong attractive force on skyrmions due to the magneto-elastic effect. The
+resultant motion is dependent on forces due to i) gradients in the local
+strain-induced magnetic anisotropy, ii) gradients in the effective anisotropy
+due to local temperature gradients, and magnetic parameters temperature
+dependences, and iii) Magnus effect acting on objects with non-zero topological
+number. Using dynamical magneto-thermo-elastic modelling, it is predicted
+skyrmions can be moved with significant velocities (up to 80 m/s shown), both
+for ferromagnetic and antiferromagnetic skyrmions, even in the presence of
+surface roughness. This mechanism of controllably moving single skyrmions in
+any direction, as well as addressing multiple skyrmions in a lattice, offers a
+new approach to constructing and studying skyrmionic devices with all-optical
+control.",2301.07034v2
+2023-01-17,Resolving the emission transition dipole moments of single doubly-excited seeded nanorods via heralded defocused imaging,"Semiconductor nanocrystal emission polarization is a crucial probe of
+nanocrystal physics and an essential factor for nanocrystal-based technologies.
+While the transition dipole moment of the lowest excited state to ground state
+transition is well characterized, the dipole moment of higher multiexcitonic
+transitions is inaccessible via most spectroscopy techniques. Here, we realize
+direct characterization of the doubly-excited state relaxation transition
+dipole by heralded defocused imaging. Defocused imaging maps the dipole
+emission pattern onto a fast single-photon avalanche diode detector array,
+allowing the post-selection of photon pairs emitted from the biexciton-exciton
+emission cascade and resolving the differences in transition dipole moments.
+Type-I1/2 seeded nanorods exhibit higher anisotropy of the biexciton-to-exciton
+transition compared to the exciton-to-ground state transition. In contrast,
+type-II seeded nanorods display a reduction of biexciton emission anisotropy.
+These findings are rationalized in terms of an interplay between transient
+dynamics of the refractive index and the excitonic fine structure.",2301.07211v1
+2023-01-25,AnisoTag: 3D Printed Tag on 2D Surface via Reflection Anisotropy,"In the past few years, the widespread use of 3D printing technology enables
+the growth of the market of 3D printed products. On Esty, a website focused on
+handmade items, hundreds of individual entrepreneurs are selling their 3D
+printed products. Inspired by the positive effects of machine-readable tags,
+like barcodes, on daily product marketing, we propose AnisoTag, a novel tagging
+method to encode data on the 2D surface of 3D printed objects based on
+reflection anisotropy. AnisoTag has an unobtrusive appearance and much lower
+extraction computational complexity, contributing to a lightweight low-cost
+tagging system for individual entrepreneurs. On AnisoTag, data are encoded by
+the proposed tool as reflective anisotropic microstructures, which would
+reflect distinct illumination patterns when irradiating by collimated laser.
+Based on it, we implement a real-time detection prototype with inexpensive
+hardware to determine the reflected illumination pattern and decode data
+according to their mapping. We evaluate AnisoTag with various 3D printer
+brands, filaments, and printing parameters, demonstrating its superior
+usability, accessibility, and reliability for practical usage.",2301.10599v2
+2023-02-03,Defect-induced magnetism in TiO$_2$: An example of quasi 2D magnetic order with perpendicular anisotropy,"Magnetic order at room temperature induced by atomic lattice defects, like
+vacancies, interstitials or pairs of them, has been observed in a large number
+of different nonmagnetic hosts, such as pure graphite, oxides and silicon-based
+materials. High Curie temperatures and time independent magnetic response at
+room temperature indicate the extraordinary robustness of this new phenomenon
+in solid state magnetism. In this work, we review experimental and theoretical
+results in pure TiO$_2$ (anatase), which magnetic order can be triggered by
+low-energy ion irradiation. In particular, we discuss the systematic
+observation of an ultrathin magnetic layer with perpendicular magnetic
+anisotropy at the surface of this oxide.",2302.01803v1
+2023-02-07,Sputtered terbium iron garnet films with perpendicular magnetic anisotropy for spintronic applications,"We report the structural, magnetic, and interfacial spin transport properties
+of epitaxial terbium iron garnet (TbIG) ultrathin films deposited by magnetron
+sputtering. High crystallinity was achieved by growing the films on gadolinium
+gallium garnet (GGG) substrates either at high temperature, or at room
+temperature followed by thermal annealing, above 750 {\deg}C in both cases. The
+films display large perpendicular magnetic anisotropy (PMA) induced by
+compressive strain, and tunable structural and magnetic properties through
+growth conditions or the substrate lattice parameter choice. The ferrimagnetic
+compensation temperature (TM) of selected TbIG films was measured through
+temperature-dependent anomalous Hall effect (AHE) in Pt/TbIG heterostructures.
+In the studied films, TM was found to be between 190-225 K, i.e., approximately
+25-60 K lower than the bulk value, which is attributed to the combined action
+of Tb deficiency and oxygen vacancies in the garnet lattice evidenced by x-ray
+photoelectron spectroscopy measurements. Sputtered TbIG ultrathin films with
+large PMA and highly tunable properties reported here can provide a suitable
+material platform for a wide range of spintronic experiments and device
+applications.",2302.03758v1
+2023-02-09,Intrinsic auxeticity and mechanical anisotropy of Si9C15 siligraphene,"The graphene-like two-dimensional (2D) silicon carbide or siligraphene has
+attracted remarkable attentions, owing to its fascinating physical properties.
+Nevertheless, the first high-quality siligraphene, i.e., monolayer Si9C15 was
+synthesised very recently, which exhibits an excellent semiconducting
+behaviour. In this work, we investigate the mechanical properties of Si9C15
+siligraphene by using atomistic simulations including density functional theory
+(DFT) calculations and molecular dynamics (MD) simulations. Both methods
+confirm the existence of intrinsic negative Poisson's ratios in Si9C15
+siligraphene, which, as illustrated by MD simulations, is attributed to the
+tension-induced de-wrinkling behaviours of its intrinsic rippled configuration.
+Different de-wrinkling behaviours are observed in different directions of
+Si9C15 siligraphene, which result in the anisotropy of its auxetic property.
+The fracture property of Si9C15 siligraphene is similarly anisotropic, but
+relatively large fracture strains are observed in different orientations,
+indicating the stretchability of Si9C15 siligraphene. The stretchability
+together with the strain-sensitive bandgap of Si9C15 siligraphene observed in
+DFT calculations indicates the effectiveness of strain engineering in
+modulating its electronic property. The combination of unique auxetic property,
+excellent mechanical property and tunable electronic property may render Si9C15
+siligraphene a novel 2D material with multifunctional applications.",2302.04409v1
+2023-02-10,Electrical characterization of the azimuthal anisotropy of $(\mathrm{Ni}_x\mathrm{Co}_{1-x})\mathrm{B}$-based ferromagnetic nanotubes,"We report on the structural, electric and magnetic properties of
+$(\mathrm{Ni}_x\mathrm{Co}_{1-x})\mathrm{B}$ ferromagnetic nanotubes,
+displaying azimuthal magnetization. The tubes are fabricated using electroless
+plating in polycarbonate porous templates, with lengths several tens of
+micrometers, diameters from 100nm to 500nm and wall thicknesses from 10nm to
+80nm. The resistivity is $\sim 1.5\times10^{-6}\mathrm{\Omega/m}$, and the
+anisotropic magnetoresistance~(AMR) of 0.2-0.3%, one order of magnitude
+larger~(resp. smaller) than in the bulk material, which we attribute to the
+resistance at grain boundaries. We determined the azimuthal anisotropy field
+from M(H) AMR loops of single tubes contacted electrically. Its magnitude is
+around 10mT, and tends to increase with the tube wall thickness, as well as the
+Co content. However, surprisingly it does not dependent much on the diameter
+nor on the curvature.",2302.05246v1
+2023-02-15,A strain-controlled magnetostrictive pseudo spin valve,"Electric-field control of magnetism via inverse magnetostrictive effect is an
+efficient path towards improving energy-efficient storage and sensing devices
+based on giant magnetoresistance effect. In this letter, we report on lateral
+electric-field driven strain-mediated modulation of magnetic properties in
+Co$/$Cu$/$Py pseudo spin valve grown on ferroelectric PMN-PT substrate. We show
+a decrease of the giant magnetoresistance ratio of the pseudo spin valve with
+increasing electric field, which is attributed to the deviation of the Co layer
+magnetization from the initial direction due to strain-induced magnetoelastic
+anisotropy contribution. Additionally, we demonstrate that strain-induced
+magnetic anisotropy effectively shifts the switching field of the
+magnetostrictive Co layer, while keeping the switching field of the nearly
+zero-magnetostrictive Py layer unaffected due to its negligible
+magnetostriction constant. We argue that magnetostrictively optimized magnetic
+films in properly engineered multilayered structures can offer a path to
+enhancing the selective magnetic switching in spintronic devices.",2302.07620v1
+2023-02-17,QCD Thermodynamics and Neutral Pion in a Uniform Magnetic Field: Finite Volume Effects,"We address finite volume effects of lattice QCD calculations in background
+magnetic fields. Using chiral perturbation theory at next-to-leading order,
+volume effects are calculated for thermodynamic quantities: the chiral
+condensate, pressure anisotropy, and magnetization. The neutral pion effective
+action in a finite volume is additionally derived. For these charge neutral
+observables, volume and source averaging are shown to capitalize on magnetic
+periodicity, which is the remnant translational invariance of the finite-volume
+theory. For a fixed magnetic field strength, certain volume and source averaged
+quantities are independent of the size of the lattice transverse to the
+magnetic field. Despite this simplifying feature, finite volume corrections to
+the magnetic field dependence of the chiral condensate and neutral pion
+magnetic polarizability can be non-negligible. The pressure anisotropy at fixed
+magnetic flux, moreover, appears acutely sensitive to the lattice volume.",2302.09179v1